FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Roden, SK AF Roden, SK TI Blood-injection-injury phobia in a commercial aviator: A case report SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE blood-injection injury phobia; commercial aviator; and behevior therapy ID EYE-MOVEMENT DESENSITIZATION AB A small percentage of the population suffers from blood-injection-injury phobia. These individuals can have vasodepressor syncope related to episodes when their phobia is triggered by a stimulus such as the sight of blood or receiving an injection. A case is presented in which a commercial aviator had a vasodepressor syncopal event during flight. She is referred for evaluation. A discussion of the diagnosis, disease, treatment, and follow-up recommendations are included. C1 Univ Texas, Med Branch, Galveston, TX 77550 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Roden, SK (reprint author), Univ Texas, Med Branch, POB 68, Seabrook, TX 77586 USA. NR 13 TC 1 Z9 1 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD DEC PY 2001 VL 72 IS 12 BP 1138 EP 1140 PG 3 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 498BV UT WOS:000172490700012 PM 11763117 ER PT J AU McCollum, G Boyle, R AF McCollum, G Boyle, R TI Conditional transitions in gaze dynamics: role of vestibular nuclei in eye-only and eye/head gaze behaviors SO BIOLOGICAL CYBERNETICS LA English DT Article ID HORIZONTAL VESTIBULOOCULAR REFLEX; MOVEMENT RELATED NEURONS; SQUIRREL-MONKEY; HEAD MOVEMENTS; PHYSIOLOGICAL-CHARACTERISTICS; FIRING BEHAVIOR; VOLUNTARY EYE; COORDINATION; OCULOMOTOR; SPACE AB The gaze control system governs distinct gaze behaviors, including visual fixation and gaze reorientations. Transitions between these gaze behaviors are frequent and smooth in healthy individuals. This study models these gaze-behavior transitions for different numbers of gaze degrees of freedom. Eye/head gaze behaviors have twice the number of degrees of freedom as eye-only gaze behaviors. Each gaze behavior is observable in the system dynamics and is correlated with neuronal behaviors in several, coordinated neural centers, including the vestibular nuclei. The coordination among the neural centers establishes a sensorimotor state which maintains each gaze behavior. This study develops a mathematical framework for synthesizing the coordination among neural centers in gaze sensorimotor states and focuses on the role of vestibular nuclei neurons in gaze sensorimotor state transitions. C1 Legacy Clin Res & Technol Ctr, Portland, OR 97232 USA. NASA, Ames Res Ctr, Ctr Bioinformat, Moffett Field, CA 94035 USA. RP McCollum, G (reprint author), Legacy Clin Res & Technol Ctr, Suite 303,1225 NE 2nd Ave, Portland, OR 97232 USA. FU NINDS NIH HHS [NS27050] NR 47 TC 4 Z9 4 U1 0 U2 1 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0340-1200 J9 BIOL CYBERN JI Biol. Cybern. PD DEC PY 2001 VL 85 IS 6 BP 423 EP 436 DI 10.1007/s004220100270 PG 14 WC Computer Science, Cybernetics; Neurosciences SC Computer Science; Neurosciences & Neurology GA 496RR UT WOS:000172410400002 PM 11762233 ER PT J AU Peddle, DR Brunke, SP Hall, FG AF Peddle, DR Brunke, SP Hall, FG TI A comparison of spectral mixture analysis and ten vegetation indices for estimating boreal forest biophysical information from airborne data SO CANADIAN JOURNAL OF REMOTE SENSING LA English DT Article; Proceedings Paper CT 22nd Symposium of the Canadian-Remote-Sensing-Society CY AUG 21-25, 2000 CL UNIV VICTORIA, VICTORIA, CANADA HO UNIV VICTORIA ID LEAF-AREA INDEX; REFLECTANCE; CANOPY; CLASSIFICATION; BIOMASS; MODELS AB Spectral Mixture Analysis (SMA) provides the capability to derive the percentage of sunlit crowns, background, and shadows within a remote sensing image pixel. This sub pixel scale information has been shown to consistently provide significantly improved estimates of forest biophysical information such as biomass, leaf area index (LAI) and net primary productivity (LAPP) compared to that provided by the normalized difference vegetation index (NDVI) using airborne and satellite imagery: However, a number of vegetation indices (VIs) have been proposed as an improvement to ND VI. In this paper, ten different VIs were used to predict forest biophysical parameters, and then compared with results obtained from SAM using airborne multispectral data from the NASA COVER Project, Superior National Forest, Minnesota USA. This data set was acquired over a range of solar zenith angles at the spatial resolution and spectral bands of the Landsat Thematic Mapper sensor. The following vegetation indices were derived from the remotely sensed data: NDVI, SR, MSR, RDVI, WDVI, GEMI, NLI, and three different soil-adjusted vegetation indices (SAVI, SAVI-1, SAVI-2). Results were obtained at solar zenith angles of 30 degrees, 45 degrees and 60 degrees for biomass, LAI NPP, DBH, stem density, and basal fraction. In all cases, SMA shadow fraction provided significantly better results than any vegetation indices, with improvements on the order of 20% compared to the best vegetation index results. In most cases, one or more of the new vegetation indices provided a small to moderate improvement compared to NDVI, with WDVI and SAVI-1 performing best amongst the [VIs, likely due to the inclusion of background reflectance. It is concluded that while different VIs can provide some improvements over ND VI, these appear to be functionally equivalent and fundamentally similar in a first-order sense in terms of their ability to predict forest biophysical parameters, which is surpassed by approaches based on subpixel image decomposition such as spectral mixture analysis and canopy optical reflectance modelling. C1 Univ Lethbridge, Dept Geog, Lethbridge, AB T1K 3M4, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. RP Peddle, DR (reprint author), Univ Lethbridge, Dept Geog, Lethbridge, AB T1K 3M4, Canada. NR 34 TC 47 Z9 47 U1 2 U2 14 PU CANADIAN AERONAUTICS SPACE INST PI OTTAWA PA 1685 RUSSELL RD, UNIT 1-R, OTTAWA, ON K1G 0N1, CANADA SN 0703-8992 J9 CAN J REMOTE SENS JI Can. J. Remote Sens. PD DEC PY 2001 VL 27 IS 6 BP 627 EP 635 PG 9 WC Remote Sensing SC Remote Sensing GA 505EF UT WOS:000172898100006 ER PT J AU Bauschlicher, CW Bakes, ELO AF Bauschlicher, CW Bakes, ELO TI The reaction of polycyclic aromatic hydrocarbon anions with hydrogen SO CHEMICAL PHYSICS LA English DT Article ID ATMOSPHERE; MOLECULES; CATIONS AB The reaction of naphthalene anion with an H atom to produce 1-hydronaphthalene anion is exothermic by about 50 kcal/mol. The exothermicity for the formation of 2-hydronaphthalene anion is 4.7 kcal/mol smaller. The 1-hydronaphthalene anion reacts with a second hydrogen atom to restore the naphthalene anion and produce H-2. This reaction has no barrier and is exothermic by 53.3 kcal/mol. Similar energetics are found for the analogous coronene and circumcoronene reactions, Thus the polycyclic aromatic hydrocarbon (PAH) anions can catalyse the formation of H-2, using a mechanism analogous to the PAH cations. This could have important consequences in several problems of astrophysical interest. Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, SETI, Moffett Field, CA 94035 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Space Technol Div, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 18 TC 14 Z9 14 U1 0 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD DEC 1 PY 2001 VL 274 IS 1 BP 11 EP 14 DI 10.1016/S0301-0104(01)00500-6 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 504QV UT WOS:000172868100002 ER PT J AU Gregory, JM Church, JA Boer, GJ Dixon, KW Flato, GM Jackett, DR Lowe, JA O'Farrell, SP Roeckner, E Russell, GL Stouffer, RJ Winton, M AF Gregory, JM Church, JA Boer, GJ Dixon, KW Flato, GM Jackett, DR Lowe, JA O'Farrell, SP Roeckner, E Russell, GL Stouffer, RJ Winton, M TI Comparison of results from several AOGCMs for global and regional sea-level change 1900-2100 SO CLIMATE DYNAMICS LA English DT Article ID OCEAN-ATMOSPHERE MODEL; TRANSIENT CLIMATE-CHANGE; EDDY-INDUCED ADVECTION; COLD START PROBLEM; CARBON-DIOXIDE; COUPLED MODEL; GREENHOUSE-GAS; THERMOHALINE CIRCULATION; CHANGE SIMULATIONS; THERMAL-EXPANSION AB Sea-level rise is an important aspect of climate change because of its impact on society and ecosystems. Here we present an intercomparison of results from ten coupled atmosphere-ocean general circulation models (AOGCMs) for sea-level changes simulated for the twentieth century and projected to occur during the twenty first century in experiments following scenario IS92a for greenhouse gases and sulphate aerosols. The model results suggest that the rate of sea-level rise due to thermal expansion of sea water has increased during the twentieth century, but the small set of tide gauges with long records might not be adequate to detect this acceleration. The rate of sea-level rise due to thermal expansion continues to increase throughout the twenty first century, and the projected total is consequently larger than in the twentieth century; for 1990-2090 it amounts to 0.20-0.37 in. This wide range results from systematic uncertainty in modelling of climate change and of heat uptake by the ocean. The AOGCMs agree that sea-level rise is expected to be geographically non-uniform, with some regions experiencing as much as twice the global average, and others practically zero, but they do not agree about the geographical pattern. The lack of agreement indicates that we cannot currently have confidence in projections of local sea-level changes, and reveals a need for detailed analysis and intercomparison in order to understand and reduce the disagreements. C1 Meterol Off, Hadley Ctr, Bracknell RG12 2SY, Berks, England. Antarctic CRC, Hobart, Tas 7001, Australia. CSIRO, Marine Res, Hobart, Tas 7001, Australia. Univ Victoria, Canadian Ctr Climate Modeling & Anal, Victoria, BC V8W 2Y2, Canada. Geophys Fluid Dynam Lab, Princeton, NJ 08542 USA. CSIRO, Atmospher Res, Aspendale, Vic 3195, Australia. Max Planck Inst Meteorol, D-20146 Hamburg, Germany. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Meterol Off, Hadley Ctr, London Rd, Bracknell RG12 2SY, Berks, England. EM jmgregory@meto.gov.uk RI Church, John/A-1541-2012; Flato, Gregory/K-6711-2015; Dixon, Keith/L-7120-2015; Gregory, Jonathan/J-2939-2016 OI Church, John/0000-0002-7037-8194; Dixon, Keith/0000-0003-3044-326X; Gregory, Jonathan/0000-0003-1296-8644 NR 60 TC 87 Z9 91 U1 0 U2 13 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0930-7575 EI 1432-0894 J9 CLIM DYNAM JI Clim. Dyn. PD DEC PY 2001 VL 18 IS 3-4 BP 225 EP 240 DI 10.1007/s003820100180 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 508QE UT WOS:000173099400005 ER PT J AU Wullschleger, SD Jackson, RB Currie, WS Friend, AD Luo, Y Mouillot, F Pan, Y Shao, GF AF Wullschleger, SD Jackson, RB Currie, WS Friend, AD Luo, Y Mouillot, F Pan, Y Shao, GF TI Below-ground processes in gap models for simulating forest response to global change SO CLIMATIC CHANGE LA English DT Article ID TERRESTRIAL BIOSPHERE MODEL; CLIMATE-CHANGE; ROOTING DEPTH; NITROGEN PRODUCTIVITY; REGIONAL APPLICATIONS; LITTER DECOMPOSITION; ECOSYSTEM PROCESSES; TEMPERATE SAVANNA; SEED-GERMINATION; SOIL-MOISTURE AB Gap models have a rich history of being used to simulate individual tree interactions that impact species diversity and patterns of forest succession. Questions arise, however, as to whether these same models can be used to study the response of forest structure and composition under a changing climate. In contrast to many process-based models, gap models have traditionally been based on rather descriptive representations of species-specific growth processes. Opportunities now exist to expand upon these simple empirical relationships with more mechanistic descriptions of growth, the response of growth to environmental variables, and competition among species for available light, water, and nutrient resources. In this paper, we focus on several areas of below-ground research with the potential to improve the utility of gap models for predicting forest composition in response to a changing climate. Specific areas for model improvement include (1) improved descriptions of the soil environment for seed germination and subsequent seedling establishment, (2) multi-layer representations of soil water and nutrient availability, (3) more accurate information on biomass allocation to roots and root distribution within the soil profile, (4) improved treatment of inter- and intra-specific competition for available soil resources, (5) increased consideration of spatial processes as related to land-surface hydrology, and (6) improved attention to above- and below-ground interactions. This list is meant to stimulate discussion and provide guidance for future field research and model development. As an example of how increased attention to below-ground processes could help address intra-specific competition for water among trees of differing size classes, the gap model LINKAGES was modified to include a sub-model of multi-layered soil hydrology. It was then used to examine the impact of root distribution within soils on the simulated drought response of seedlings, saplings, and mature trees. An annual simulation of soil water content for a deciduous forest in eastern Tennessee showed that seedlings whose roots were restricted to the upper 20-cm of the soil experienced far more 'drought days' than did saplings and larger trees that otherwise had access to deeper soil water reserves. We recognize that models of forest succession cannot include mechanistic detail on all potential below-ground processes and that there are obvious tradeoffs between model simplicity and more sophisticated parameterizations. We conclude, however, that feedbacks among global environmental change, seed germination and seedling establishment, above- and below-ground carbon allocation, root distribution within the soil profile, and soil water and nutrient dynamics will be critically important for predicting forest dynamics and ecosystem function in the 21st century. As a result, steps should now be taken to ensure that these processes are represented in future gap models. C1 Oak Ridge Natl Lab, Div Environm Sci, Oak Ridge, TN 37831 USA. Duke Univ, Dept Bot, Durham, NC 27708 USA. Duke Univ, Nicholas Sch Environm, Durham, NC 27708 USA. Appalachian Lab, Frostburg, MD 21532 USA. Rutgers State Univ, Ctr Environm Predict, New Brunswick, NJ 08901 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Univ Oklahoma, Dept Bot & Microbiol, Norman, OK 73019 USA. CNRS, CEFE, Dynam React Ecosyst Anal Spatiale & Modelisat Uni, F-34293 Montpellier 5, France. Univ Corse, F-20250 Corte, France. US Forest Serv, USDA, Newtown Sq, PA 19073 USA. Purdue Univ, Dept Forestry & Nat Resources, W Lafayette, IN 47907 USA. RP Wullschleger, SD (reprint author), Oak Ridge Natl Lab, Div Environm Sci, POB 2008, Oak Ridge, TN 37831 USA. RI Wullschleger, Stan/B-8297-2012; MOUILLOT, florent/C-2204-2015; Pan, Yude/F-6145-2015 OI Wullschleger, Stan/0000-0002-9869-0446; MOUILLOT, florent/0000-0002-6548-4830; NR 92 TC 27 Z9 33 U1 2 U2 24 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD DEC PY 2001 VL 51 IS 3-4 BP 449 EP 473 DI 10.1023/A:1012570821241 PG 25 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 488NU UT WOS:000171943200008 ER PT J AU Hurst, V Beck, G Bacal, K Hamilton, D McDonald, PV Logan, JS AF Hurst, V Beck, G Bacal, K Hamilton, D McDonald, PV Logan, JS TI Cardiac events during space flight SO CRITICAL CARE MEDICINE LA English DT Meeting Abstract C1 Wyle Labs, Houston, TX USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0090-3493 J9 CRIT CARE MED JI Crit. Care Med. PD DEC PY 2001 VL 29 IS 12 SU S MA 169 BP A55 EP A55 PG 1 WC Critical Care Medicine SC General & Internal Medicine GA 505PJ UT WOS:000172920900169 ER PT J AU Shoemaker, WC Bayard, DS Botnen, A Wo, CC Jelliffe, RW AF Shoemaker, WC Bayard, DS Botnen, A Wo, CC Jelliffe, RW TI Hemodynamic evaluation and outcome prediction of noninvasive monitored emergency patients by a stochastic control program SO CRITICAL CARE MEDICINE LA English DT Meeting Abstract C1 Univ So Calif, Los Angeles, CA 90089 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0090-3493 J9 CRIT CARE MED JI Crit. Care Med. PD DEC PY 2001 VL 29 IS 12 SU S MA 627 BP A189 EP A189 PG 1 WC Critical Care Medicine SC General & Internal Medicine GA 505PJ UT WOS:000172920900623 ER PT J AU Warren-Rhodes, K Koenig, A AF Warren-Rhodes, K Koenig, A TI Ecosystem appropriation by Hong Kong and its implications for sustainable development SO ECOLOGICAL ECONOMICS LA English DT Article DE ecological footprints; ecosystem appropriation; Hong Kong; China; Guangzhou; pollution ID ECOLOGICAL FOOTPRINT AB The Hong Kong Special Administrative Region is a highly developed modern city where technical and economic advances have made it possible to support 7 million people on 120 km(2) of built-up land, resulting in 58 000 people per km(2), one of the highest population densities in the world. This population depends on a continual supply of materials, energy and information to function, and these resources are mainly supplied from outside Hong Kong's own geographical boundaries. The ecological footprint (EF) of Hong Kong due to its direct and indirect consumption of renewable resources and waste generation is presented. Additionally, the paper traces the spatial patterns of Hong Kong's EF and examines the implications of this ecosystem appropriation. The study finds an EF for Hong Kong of about 6 ha per capita, with the largest appropriation occurring for marine ecosystems. If the impacts of fish farming are included, Hong Kong appropriates a marine area nearly 2000 times its own built-up city area, Current resource consumption and waste generation patterns in Guangdong, China - where much of Hong Kong's terrestrial ecosystem appropriation occurs - are also discussed. (C) 2001 Elsevier Science BN. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Hong Kong, Dept Civil Engn, Hong Kong, Hong Kong, Peoples R China. RP Warren-Rhodes, K (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 40 TC 27 Z9 36 U1 4 U2 14 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8009 J9 ECOL ECON JI Ecol. Econ. PD DEC PY 2001 VL 39 IS 3 BP 347 EP 359 DI 10.1016/S0921-8009(01)00194-X PG 13 WC Ecology; Economics; Environmental Sciences; Environmental Studies SC Environmental Sciences & Ecology; Business & Economics GA 504TE UT WOS:000172871300003 ER PT J AU Kleeman, MJ Eldering, A Hall, JR Cass, GR AF Kleeman, MJ Eldering, A Hall, JR Cass, GR TI Effect of emissions control programs on visibility in southern California SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Article ID PARTICULATE AIR-POLLUTION; OPTICAL-PROPERTIES; MODEL; AEROSOLS; SIZE; SCATTERING AB A new method for the analysis and display of the effect of emissions controls on visibility is applied to conditions in southern California. An advanced mechanistic air quality model that represents airborne particles as a source-oriented external mixture first is used to track emissions source contributions to the size distribution and chemical composition of airborne particles at Claremont, CA, under heavy smog conditions. The resulting description of the aerosol is used in a Mie scattering calculation to determine the magnitude and particle size dependence of light scattering and absorption in the atmosphere. The resulting light scattering and absorption coefficient values are supplied to an image processing-based visibility model that creates full color representations of the appearance of the local terrain in the presence of the specified level of air pollution based on satellite-generated landscape images. By linking these models, a direct connection is established between source emissions and resulting visual air quality. The composite modeling system then is used to study the effect that different emissions control strategies would have on visibility in southern California. An aggressive program of 92 specific emissions control measures that include primary particle controls plus controls on reactive gases that act as secondary aerosol precursors would more than double visual range at Claremont under the 1987 historical conditions studied. Synthetic landscape images show that the mountains to the north of Claremont that are not visible at a range of 10 km under base-case conditions would be visible if the emissions controls described above were applied. C1 Univ Calif Davis, Dept Civil & Environm Engn, Davis, CA 95616 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. RP Kleeman, MJ (reprint author), Univ Calif Davis, Dept Civil & Environm Engn, Davis, CA 95616 USA. NR 30 TC 13 Z9 14 U1 0 U2 8 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0013-936X J9 ENVIRON SCI TECHNOL JI Environ. Sci. Technol. PD DEC 1 PY 2001 VL 35 IS 23 BP 4668 EP 4674 DI 10.1021/es001865f PG 7 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA 498TU UT WOS:000172527200025 PM 11770769 ER PT J AU Ansari, RR Suh, KI Dunker, S Kitaya, N Sebag, J AF Ansari, RR Suh, KI Dunker, S Kitaya, N Sebag, J TI Quantitative molecular characterization of bovine vitreous and lens with non-invasive dynamic light scattering SO EXPERIMENTAL EYE RESEARCH LA English DT Article DE dynamic light scattering; non-invasive; laser; diagnostics; vitreous; lens; molecular structure; cataract; vitreous degeneration ID SPECTROSCOPY; DETACHMENT; SYSTEM; PROBE AB The non-invasive technique of dynamic light scattering (DLS) was used to quantitatively characterize vitreous and lens structure on a molecular level by measuring the sizes of the predominant particles and mapping the three-dimensional topographic distribution of these structural macromolecules in three spatial dimensions. The results of DLS measurements in five fresh adult bovine eyes were compared to DLS measurements in model solutions of hyaluronan (HA) and collagen (Coll). In the bovine eyes DLS measurements were obtained from excised samples of gel and liquid vitreous and compared to the model solutions. Measurements in whole vitreous were obtained at: multiple points posterior to the lens to generate a three-dimensional 'map' of molecular structure. The macromolecule distribution in bovine lens was similarly characterized. In each bovine vitreous (Bo Vit) specimen, DLS predominantly detected two distinct particles, which differed in diffusion properties and hence size. Comparisons with model vitreous solutions demonstrated that these most likely corresponded to the Coll and HA components of vitreous. Three-dimensional mapping of Bo Vit found heterogeneity, throughout the vitreous body, with different particle size distributions for Coll and HA at different loci. In contrast, the three-dimensional distribution of lens macromolecules was more homogeneous. Thus, the non-invasive DLS technique can quantitate the average sizes of vitreous and lens macromolecules and map their three-dimensional distribution. This method to assess quantitatively the inacromolecular structure of vitreous and lens should be useful for clinical as well as experimental applications in health and disease. (C) 2001 Academic Press. C1 NASA, Glenn Res Ctr, Cleveland, OH USA. Univ So Calif, Keck Sch Med, Doheny Eye Inst, Los Angeles, CA USA. Univ Marburg, Dept Ophthalmol, Marburg, Germany. Asahikawa Med Coll, Dept Ophthalmol, Asahikawa, Hokkaido 078, Japan. RP Sebag, J (reprint author), 18821 Delaware St,Suite 202, Huntington Beach, CA 92648 USA. OI Sebag, J/0000-0001-8648-5747 NR 16 TC 20 Z9 21 U1 1 U2 5 PU ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0014-4835 J9 EXP EYE RES JI Exp. Eye Res. PD DEC PY 2001 VL 73 IS 6 BP 859 EP 866 DI 10.1006/exer.2001.1097 PG 8 WC Ophthalmology SC Ophthalmology GA 517HK UT WOS:000173604900011 PM 11846516 ER PT J AU Hoehler, TM Alperin, MJ Albert, DB Martens, CS AF Hoehler, TM Alperin, MJ Albert, DB Martens, CS TI Apparent minimum free energy requirements for methanogenic Archaea and sulfate-reducing bacteria in an anoxic marine sediment SO FEMS MICROBIOLOGY ECOLOGY LA English DT Article DE anoxic sediment; hydrogen; critical free energy ID HYDROGEN CONCENTRATIONS; ANAEROBIC-BACTERIA; METHANE PRODUCTION; METABOLISM; ENERGETICS; OXIDATION; DEEP; TEMPERATURE; CONSORTIUM; BIOSPHERE AB Among the most fundamental constraints governing the distribution of micro organisms in the environment is the availability of chemical energy at biologically useful levels. To assess the minimum free energy yield that can support microbial metabolism in situ, we examined the thermodynamics of H-2-consuming processes in anoxic sediments from Cape Lookout Bight, NC, USA. Depth distributions of H-2 partial pressure, along with a suite of relevant concentration data, were determined in sediment cores collected in November (at 14.5 degreesC) and August (at 27 degreesC) and used to calculate free energy yields for methanogenesis and sulfate reduction. At both times of year, and for both processes, free energy yields gradually decreased (became less negative) with depth before reaching an apparent asymptote. Sulfate-reducing bacteria exhibited an asymptote of -19.1 +/-1.7 kJ (mol SO42-)(-1), while methanogenic Archaea were apparently supported by energy yields as small as -10.6 +/-0.7 kJ (mol CH4)(-1). (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ N Carolina, Dept Marine Sci, Chapel Hill, NC 27599 USA. RP Hoehler, TM (reprint author), NASA, Ames Res Ctr, MS 239-4, Moffett Field, CA 94035 USA. NR 51 TC 112 Z9 116 U1 0 U2 30 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-6496 J9 FEMS MICROBIOL ECOL JI FEMS Microbiol. Ecol. PD DEC PY 2001 VL 38 IS 1 BP 33 EP 41 DI 10.1111/j.1574-6941.2001.tb00879.x PG 9 WC Microbiology SC Microbiology GA 506TQ UT WOS:000172988200004 ER PT J AU Argus, DF Gordon, RG AF Argus, DF Gordon, RG TI Present tectonic motion across the Coast Ranges and San Andreas fault system in central California SO GEOLOGICAL SOCIETY OF AMERICA BULLETIN LA English DT Article DE Calaveras fault; Coast ranges; Diablo range; San Andreas fault; San Francisco Bay; Sierra Nevada ID BASE-LINE INTERFEROMETRY; WESTERN UNITED-STATES; PACIFIC PLATE BOUNDARY; NORTH-AMERICA MOTION; RELATIVE MOTIONS; FRACTURE-ZONE; SPACE GEODESY; DEFORMATION; SLIP; KINEMATICS AB Geodetic results from very long baseline interferometry (VLBI), satellite laser ranging (SLR), and the Global Positioning System (GPS) are used to estimate angular velocities between the Sierran microplate, Pacific plate, and North American plate. The Sierra-Pacific pole of rotation lies nearer to the San Andreas fault than does the Pacific-North America pole of rotation and leads to different tectonic implications than if the latter is used. The angular velocities show that the San Andreas fault system and central California Coast Ranges accommodate motion of 39 +/- 2 mm/yr, mainly by strike-slip faulting. (All confidence limits following +/- signs in this paper are 95% confidence limits.) Fault-normal motion is small, is mainly convergent (at rates up to 3.3 +/- 1.0 mm/yr), and varies along the coast, but is divergent (at 2.6 +/- 1.2 mm/yr) across San Pablo Bay and associated topographic lows across which the Sierran and Central Valley watershed drains to the Pacific Ocean. The mountain ranges tend to be larger where the fault-normal convergence rates are larger. The low convergence rate (0.5 +/- 1.8 mm/yr) normal to the San Andreas fault in the Carrizo Plain differs sharply from that previously inferred (8.2 +/- 1.2 mm/yr and 4.9 +/- 1.6 mm/yr) by Feigl et al. (1993). The difference is due to differences between their and our elastic strain accumulation models and between how their and our Pacific plate reference frames are defined. The ranges in most places require a minimum of 4 (+2)/(-1), m.y. of fault-normal convergence at the present rate to attain their present cross-sectional area if erosion is neglected, more if it is not. The amount of convergence previously estimated from a balanced cross section across the Diablo Range in central California requires 10 (+8)/(-3) m.y. of convergence at the present rate. The former is consistent with widely held views about the onset of the Coast Range orogeny, but the latter is not. Both are consistent, however, with the recent plate reconstructions by S. Cande, J. Stock, and colleagues, which indicate that Pacific plate motion relative to North America changed to a more convergent direction, 20 degrees -25 degrees clockwise of its prior direction, at ca. 8 to 6 Ma and not at 3.5 Ma, as had been previously inferred. The inferred change in direction of plate motion is large compared with the present angle of convergence across the straight and narrow segment of the San Andreas fault of 0.7 degrees -4.7 degrees, from which we infer that the Sierran microplate changed motion relative to North America at the same time (ca. 8 to 6 Ma) as did the Pacific plate. We further infer that the motion accommodated across the Great Basin must also have changed at the same time. We also examine the hypothesis that stable sliding occurs along the San Andreas fault and other northwest-striking strike-slip faults in central California where the fault-normal convergence rate is low or negative, and that these faults are unstable where the fault-normal convergence rate is high. Such a relationship appears to hold in general, but fails in detail. In particular, there are substantial sections of fault with small inferred rates of fault-normal convergence across which the San Andreas fault is locked. Moreover, the creeping section of the San Andreas fault (i.e., the section between Parkfield and the Calaveras junction) is the locus of greater fault-normal convergence (3.2 +/- 1.4 mm/yr) than is the locked part of the fault (0.5 +/- 1.8 mm/yr) south of Parkfield. Thus, this hypothesis is at best a partial explanation for the observed distribution of locked and nonlocked sections of the fault. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Rice Univ, Dept Earth Sci, Houston, TX 77005 USA. RP Argus, DF (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Argus, Donald/F-7704-2011 NR 51 TC 140 Z9 140 U1 1 U2 31 PU ASSOC ENGINEERING GEOLOGISTS GEOLOGICAL SOCIETY AMER PI COLLEGE STN PA TEXAS A & M UNIV, DEPT GEOLOGY & GEOPHYSICS, COLLEGE STN, TX 77843-3115 USA SN 0016-7606 J9 GEOL SOC AM BULL JI Geol. Soc. Am. Bull. PD DEC PY 2001 VL 113 IS 12 BP 1580 EP 1592 DI 10.1130/0016-7606(2001)113<1580:PTMATC>2.0.CO;2 PG 13 WC Geosciences, Multidisciplinary SC Geology GA 501CP UT WOS:000172665600006 ER PT J AU Treuhaft, RN Lowe, ST Zuffada, C Chao, Y AF Treuhaft, RN Lowe, ST Zuffada, C Chao, Y TI 2-cm GPS altimetry over Crater Lake SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RADIO AB Differences in electromagnetic path delay, between direct Global Positioning System (CPS) signals and those reflected from the surface of Crater Lake, have led to lake surface height estimates with 2-cm precision in 1 second. This is the first high-precision altimetric demonstration with CPS from sufficient altitude (approximate to 480 m) to probe fundamental experimental errors, which bear on future air- and spaceborne passive CPS altimetry. It also serves as the first demonstration of a new approach to altimetric remote sensing in the coastal region, an area that is poorly measured by conventional radar altimetry. Time-series analyses suggest that tropospheric and thermal noise fluctuations dominate the altimetric error in this experiment. Estimating the differential delay from several simultaneously visible satellites may enable tropospheric error estimation and correction. Thermal noise on the reflected signal will be reduced with fully polarimetric observations arid larger antenna apertures. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Treuhaft, RN (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 138-212, Pasadena, CA 91109 USA. NR 18 TC 66 Z9 71 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2001 VL 28 IS 23 BP 4343 EP 4346 DI 10.1029/2001GL013815 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 496YJ UT WOS:000172425700001 ER PT J AU Mulligan, T Russell, CT Anderson, BJ Acuna, MH AF Mulligan, T Russell, CT Anderson, BJ Acuna, MH TI Multiple spacecraft flux rope modeling of the Bastille Day magnetic cloud SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The Bastille Day magnetic cloud in July 2000 occurred with NEAR in conjunction with the Earth at a radial distance of 1.76 AU and 1.9 degrees from the Earth-Sun line. Propagation time from ACE at 0.99 AU to NEAR indicates the cloud did not decelerate significantly between the Earth and 1.76 AU. Using a non-force-free, kinematic flux rope model we find the rope contained 130 TWb of magnetic flux, was oriented with clock and cone angles of 50 degrees and 83 degrees, and had a radius of 0.25 AU at ACE. At NEAR its radius had expanded to 0.43 AU. Simultaneous modeling, of ACE and NEAR data indicate the axial and poloidal magnetic fields vary as R-1.4 and R-1.2 where R is heliocentric distance. Magnetosheath thicknesses of 0.14 AU and 0.23 AU indicate the rope cross section is elongated normal to the cloud axis and the radial direction. C1 Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90096 USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90096 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Mulligan, T (reprint author), Univ Calif Los Angeles, Inst Geophys & Planetary Phys, 405 Hilgard Ave, Los Angeles, CA 90096 USA. RI Anderson, Brian/I-8615-2012; OI Russell, Christopher/0000-0003-1639-8298 NR 15 TC 28 Z9 28 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2001 VL 28 IS 23 BP 4417 EP 4420 DI 10.1029/2001GL013293 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 496YJ UT WOS:000172425700020 ER PT J AU Turner, DD Ferrare, RA Brasseur, LA AF Turner, DD Ferrare, RA Brasseur, LA TI Average aerosol extinction and water vapor profiles over the southern great plains SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RAMAN LIDAR; SITE AB An operational Raman lidar deployed at the DOE Atmospheric Radiation Measurement site in Oklahoma has collected more than 7500 h of aerosol and water vapor data between April 1998 and January 2000. These data, which span a wide variety of atmospheric conditions, have been analyzed as a function of season, integrated amount, and time of day. The scale height of the mean aerosol profiles varies considerably as both a function of season and aerosol optical thickness, with the mean scale height increasing from less than I km in the winter to over 2 km during turbid summer days. The mean scale height of the water vapor remained very close to 2 km, regardless of season or precipitable water vapor. Furthermore, the distribution of aerosol optical thickness shows a slight shift to smaller values at night compared to day, and the mean aerosol profiles show little diurnal dependence except at the top of the boundary layer. C1 Pacific NW Natl Lab, Climate Dynam Grp, Richland, WA 99352 USA. NASA, Langley Res Ctr, Chem & Dynam Branch, Hampton, VA 23681 USA. NASA, Langley Res Ctr, SAIC, Hampton, VA 23681 USA. RP Turner, DD (reprint author), Univ Wisconsin, 1225 W Dayton St, Madison, WI 53706 USA. NR 9 TC 39 Z9 40 U1 2 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2001 VL 28 IS 23 BP 4441 EP 4444 DI 10.1029/2001GL013691 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 496YJ UT WOS:000172425700026 ER PT J AU Manney, GL Sabutis, JL Swinbank, R AF Manney, GL Sabutis, JL Swinbank, R TI A unique stratospheric warming event in November 2000 (vol 28, pg 4457, 2001) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Correction C1 New Mexico Highlands Univ, Dept Nat Resources Management, Las Vegas, NM 87701 USA. New Mexico Highlands Univ, Sch Educ, Las Vegas, NM 87701 USA. Meteorol Off, Bracknell RG12 2SZ, Berks, England. RP Manney, GL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2001 VL 28 IS 23 BP 4457 EP 4457 DI 10.1029/2001GL014053 PG 1 WC Geosciences, Multidisciplinary SC Geology GA 496YJ UT WOS:000172425700030 ER PT J AU Gornitz, V Couch, S Hartig, EK AF Gornitz, V Couch, S Hartig, EK TI Impacts of sea level rise in the New York City metropolitan area SO GLOBAL AND PLANETARY CHANGE LA English DT Article; Proceedings Paper CT Conference on Global and Regional Sea-Level Changes and the Hydrological Cycle CY OCT, 1999 CL SARDINIA, ITALY DE sea level rise; climate change; impacts ID GLACIAL ISOSTATIC-ADJUSTMENT; CLIMATE-CHANGE; CYCLONES; RECORD; MODEL AB The greater New York City region, with over 2400 km of shoreline, will be vulnerable to accelerated sea level rise (SLR) due to anticipated climate warming. Accelerated SLR would exacerbate historic trends of beach erosion and attrition of highly productive coastal salt marshes. Coastal populations in the region have swelled by around 17% (av.) and over 100% in some localities between 1960 and 1995. The coastal zone will thus be increasingly at risk to episodic flood events superimposed on a more gradual rise in mean sea level. Projections of sea level rise based on a suite of climate change scenarios suggest that sea levels will rise by 18-60 cm by the 2050s, and 24-108 cm by the 2080s over late 20th century levels. The return period of the 100-yr storm flood could be reduced to 19-68 years, on average, by the 2050s, and 4-60 years by the 2080s. Around 50% of the land surface of salt marsh islands have disappeared in Jamaica Bay since 1900. While losses prior to stricter environmental protection starting in 1972 can largely be attributed to anthropogenic activities, such as landfilling, dredging, and urbanization, further investigation is needed to explain more recent shrinkage. Given projected rates of SLR, and plausible accretion rates, these wetlands may not keep pace with SLR beyond several decades, resulting in severe loss. (C) 2002 Elsevier Science B.V All rights reserved. C1 Columbia Univ, Ctr Climate Syst Res, New York, NY 10025 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. USA, Corps Engineers, New York, NY USA. Lamont Doherty Earth Observ, Wildlife Trust, Palisades, NY USA. RP Gornitz, V (reprint author), Columbia Univ, Ctr Climate Syst Res, Armstrong Hall 2880,Broadway, New York, NY 10025 USA. NR 65 TC 40 Z9 41 U1 3 U2 30 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD DEC PY 2001 VL 32 IS 1 SI SI BP 61 EP 88 AR PII S0921-8181(01)00150-3 DI 10.1016/S0921-8181(01)00150-3 PG 28 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 525QC UT WOS:000174081600007 ER PT J AU Cano, RJ Hou, TH Weiser, ES St Clair, TL AF Cano, RJ Hou, TH Weiser, ES St Clair, TL TI Polyimide composites from 'salt-like' solution precursors SO HIGH PERFORMANCE POLYMERS LA English DT Article AB Four NASA Langley-developed polyimide matrix resins, LaRC(TM)-IA, LaRC(TM)-IAX, LaRC(TM)-8515 and LaRC(TM)-PETI-5, were produced via a 'saltlike' process developed by Unitika Ltd. The salt-like solutions (65% solids in NMP) were prepregged onto Hexcel IM7 carbon fibre using the NASA LaRC(TM) multipurpose tape machine. Process parameters were determined and composite panels fabricated. The temperature dependent volatile depletion rates, the thermal crystallization behaviour and the resin rheology were characterized. Composite moulding cycles were developed which consistently yielded well consolidated, void-free laminated parts. Composite mechanical properties such as the short beam shear strength; the longitudinal and transverse flexural strength and flexural modulus; the longitudinal compression strength and modulus; and the open hole compression strength and compression after impact strength were measured at room temperature and elevated temperatures. The processing characteristics and the composite mechanical properties of the four intermediate modulus carbon fibre/polyimide matrix composites were compared to existing data on the same polyimide resin systems and IM7 carbon fibre manufactured via poly(amide acid) solutions (30-35% solids in NMP). This work studies the effects of varying the synthetic route on the processing and mechanical properties of the polyimide composites. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Cano, RJ (reprint author), NASA, Langley Res Ctr, 6A W Taylor St, Hampton, VA 23681 USA. NR 22 TC 6 Z9 6 U1 2 U2 10 PU SAGE PUBLICATIONS LTD PI LONDON PA 6 BONHILL STREET, LONDON EC2A 4PU, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD DEC PY 2001 VL 13 IS 4 BP 235 EP 250 AR PII S0954-0083(01)25731-6 DI 10.1088/0954-0083/13/4/302 PG 16 WC Polymer Science SC Polymer Science GA 549RK UT WOS:000175460400002 ER PT J AU Delvigs, P Klopotek, DL Hardy-Green, D AF Delvigs, P Klopotek, DL Hardy-Green, D TI Addition polyimides from non-mutagenic diamines SO HIGH PERFORMANCE POLYMERS LA English DT Article ID PROPERTY RELATIONSHIPS; RESINS AB Studies were conducted to find an acceptable non-mutagenic diamine to replace 4,4'-methylonedianiline (MDA), a suspect carcinogen, which is currently being used in PMR-15 polyimide applications. Several diamines containing fluorine and trifluoromethyl substituent groups were synthesized. The diamines were polymerized with the dimethyl ester of 3,3',4,4'-benzophenonetetracarboxylic acid (BTDE), using the monomethyl ester of nadic acid (NE) as an endcap. The effect of diamine structure on theological properties, glass transition temperature, and thermo-oxidative stability was investigated. Unidirectional laminates were fabricated from selected resins, using carbon fibre as the reinforcement. The results indicate that some of the diamines containing trifluoromethyl groups are non-mutagenic, and have potential to replace MDA in PMR polyimides for long-term applications at temperatures up to 300 degreesC. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. St Norbert Coll, De Pere, WI 54115 USA. Univ Akron, Akron, OH 44325 USA. RP Delvigs, P (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 16 TC 5 Z9 5 U1 0 U2 3 PU SAGE PUBLICATIONS LTD PI LONDON PA 6 BONHILL STREET, LONDON EC2A 4PU, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD DEC PY 2001 VL 13 IS 4 BP 301 EP 312 AR PII S0954-0083(01)28955-7 DI 10.1088/0954-0083/13/4/308 PG 12 WC Polymer Science SC Polymer Science GA 549RK UT WOS:000175460400008 ER PT J AU Thompson, CM Hergenrother, PM AF Thompson, CM Hergenrother, PM TI Phenylethynyl terminated arylene ether oxadiazole and triazole oligomers and their cured polymers SO HIGH PERFORMANCE POLYMERS LA English DT Article AB Several novel phenylethynyl terminated arylene ether oligomers containing oxadiazole and triazole rings were prepared as part of an effort to develop high performance polymers with an attractive combination of properties (e.g. processability and mechanical performance) for future NASA applications. The oligomers displayed low melt viscosities and good solubilities. Thin films cast from solutions of the oligomers and cured for one hour at 350degreesC in air gave good tensile properties. Titanium to titanium (6Al-4V) tensile shear specimens were readily fabricated and provided moderate strengths. The chemistry and properties of these new materials are discussed. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Thompson, CM (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 8 TC 12 Z9 12 U1 1 U2 4 PU SAGE PUBLICATIONS LTD PI LONDON PA 6 BONHILL STREET, LONDON EC2A 4PU, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD DEC PY 2001 VL 13 IS 4 BP 313 EP 322 AR PII S0954-0083(01)29931-0 DI 10.1088/0954-0083/13/4/309 PG 10 WC Polymer Science SC Polymer Science GA 549RK UT WOS:000175460400009 ER PT J AU Hou, TH Belvin, HL Johnston, NJ AF Hou, TH Belvin, HL Johnston, NJ TI Automated tow placed LARC(TM)-PETI-5 composites SO HIGH PERFORMANCE POLYMERS LA English DT Article AB LARC(TM)-PETI-5 is a PhenylEthynyl-Terminated In-tide resin developed at NASA Langley Research Center (LARC) during the 1990s. It offers a combination of attractive composite and adhesive properties. IM7/LARC(TM)-PETI-5 composites exhibit thermal and thermo-oxidative stability typical of polyimides, superior chemical resistance and processability, excellent mechanical properties, toughness and damage tolerance. It was selected for study in the High Speed Research program aimed at developing technologies for a future supersonic aircraft, the High Speed Civil Transport, with a projected life span of 60 000 h at a cruise speed up to March 2.4. Robust autoclave processing cycles for LARC(TM)-PETI-5 composites have been thoroughly designed and demonstrated, which involved hand lay-up of solvent-ladened 'wet' prepregs. However, this type of processing is not only costly but also environmentally unfriendly. Volatile management and shrinkage could become serious problems in the fabrication of large complex air-frame structural subcomponents. Robotic tow placement technology utilizing 'dry' material forms represents a new fabrication process which overcomes these deficiencies. This work evaluates and compares mechanical properties of composites fabricated by heated head automated tow placement (dry process) with those obtained by hand lay-up/autoclave fabrication (wet process). Thermal and rheological properties of the robotically as-placed uncured composites were measured. A post-cure cycle was designed due to the requirement of the PETI-5 resin for a 370degreesC/1 h hold to reach full cure, conditions which cannot be duplicated during heated head robotic placement. Mechanical properties such as 0degrees flexural strength and modulus, open hole tensile and compressive strength and moduli, reduced section compression dogbone compressive strength, and modified zippora-medium small (MZ-MS) tensile and compressive properties were obtained on the post-cured panels. These properties compared favourably with those obtained from the wet process. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hou, TH (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 12 TC 3 Z9 3 U1 1 U2 4 PU SAGE PUBLICATIONS LTD PI LONDON PA 6 BONHILL STREET, LONDON EC2A 4PU, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD DEC PY 2001 VL 13 IS 4 BP 323 EP 336 AR PII S0954-0083(01)29771-2 DI 10.1088/0954-0083/13/4/310 PG 14 WC Polymer Science SC Polymer Science GA 549RK UT WOS:000175460400010 ER PT J AU Butler, BJ Steffes, PG Suleiman, SH Kolodner, MA Jenkins, JM AF Butler, BJ Steffes, PG Suleiman, SH Kolodner, MA Jenkins, JM TI Accurate and consistent microwave observations of Venus and their implications SO ICARUS LA English DT Article DE Venus; radio observations; radiative transfer ID SULFUR-DIOXIDE SO2; LABORATORY MEASUREMENTS; MAGELLAN SPACECRAFT; RADIO OCCULTATION; DARK SIDE; ATMOSPHERE; SURFACE; EMISSION; PERFORMANCE; ABSORPTION AB We present observations of Venus at six frequencies: 1.385, 1.465, 4.86, 8.44, 14.94, and 22.46 GHz. These were obtained with the Very Large Array and calibrated in a consistent fashion. The brightness temperature of Venus at the six frequencies is derived and compared to a model which includes the emission from the atmosphere, surface, and subsurface of Venus. A single set of model inputs can fit the higher frequency data, where the emission comes mostly from the atmosphere. At the lower frequencies, where emission comes mostly from the surface and subsurface, the model has difficulty reproducing the measurements, and the lowest two frequencies are not reproduced well at all. Improvements in this model over past models include new formalisms for the microwave opacity Of SO2 and H2SO4 and incorporation of measured topography and surface characteristics from Magellan. The inputs to the model which best fit the higher frequency data include a relatively warm temperature profile (more consistent with the Mariner V occultation temperature profile than that from the Pioneer-Venus sounders), a disk-averaged abundance of gaseous H2SO4 of 1-2.5 ppm at and just below the lower cloud layer, and an average SO2 abundance of 50 ppm for all altitudes below the cloud layers. This H2SO4 abundance is consistent with the values inferred from Magellan occultations, taking into account the differences between equatorial and polar locations. The SO2 abundance in the lower atmosphere is in agreement with earlier results of P. G. Steffes, M. J. Kfein, and J. M. Jenkins (1990, Icarus 84, 83-92), but much lower than the 180 ppm inferred from the Pioneer sounder probe or the 130 ppm inferred from infrared observations. Models with as much as 130 ppm of SO2 fit the measurements only if the atmosphere is nearly completely devoid of H2SO4 and the temperature profile which is much warmer than that measured by the Pioneer-Venus probes is used. (C) 2001 Elsevier Science (USA). C1 Natl Radio Astron Observ, Socorro, NM 87801 USA. Georgia Inst Technol, Sch Elect & Comp Engn, Atlanta, GA 30332 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Butler, BJ (reprint author), Natl Radio Astron Observ, POB O, Socorro, NM 87801 USA. NR 63 TC 12 Z9 12 U1 0 U2 2 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2001 VL 154 IS 2 BP 226 EP 238 DI 10.1006/icar.2001.6710 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ZC UT WOS:000175016200001 ER PT J AU Moore, JM Wilhelms, DE AF Moore, JM Wilhelms, DE TI Hellas as a possible site of ancient ice-covered lakes on Mars SO ICARUS LA English DT Article ID GROUND ICE; REGION; GLACIATION; EVOLUTION; CLIMATE; MODEL; ROCKS; BASIN AB Based on topographic, morphologic, and stratigraphic evidence, we propose that ancient water-laid sediment is the dominant component of deposits within Hellas Planitia, Mars. Multiple-layered sediment is manifested by alternating benches and scarps visible in Mars orbiting camera narrow-angle (MOC NA) images. Viking Orbiter camera and MOC NA images were used to map contacts and stratigraphically order the different materials units within Hellas. Mars orbiting laser altimeter (MOLA) data reveal that the contacts of these sedimentary units, as well as a number of scarps or other abrupt changes in landscape texture, trace contours of constant elevation for thousands of km, and in one case all around the basin. Channels, consensually interpreted to be cut by water, lead into the basin. MOLA results indicate that the area encompassed by greater Hellas' highest closed contour is nearly one-fifth that of the entire northern plains, making the Hellas "drainage" area much larger than previously reported. If lakes formed under climatic conditions similar to the modern Martian climate, they would develop thick ice carapaces, then the lakes would eventually sublimate away. Two units within Hellas exhibit a reticulate or honeycomb pattern, which we speculate are impressions made by lake-lowered ice blocks grounding into initially soft mud. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. US Geol Survey, Astrogeol Branch, Monte Rio, CA 95462 USA. RP Moore, JM (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. NR 54 TC 69 Z9 71 U1 3 U2 8 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2001 VL 154 IS 2 BP 258 EP 276 DI 10.1006/icar.2001.6736 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ZC UT WOS:000175016200004 ER PT J AU Lamy, PL Toth, I A'Hearn, MF Weaver, HA Weissman, PR AF Lamy, PL Toth, I A'Hearn, MF Weaver, HA Weissman, PR TI Hubble space telescope observations of the nucleus of Comet 9P/Tempel 1 SO ICARUS LA English DT Article ID INNER COMA; PHOTOMETRY AB The nucleus of Comet 9P/Tempel 1, the target of the Deep Impact mission, was detected during Hubble Space Telescope observations taken with the wide-field planetary camera 2 (WFPC2) on 31 December 1997 when the comet's solar phase angle was 3.degrees8, its heliocentric distance was 4.48 AU, and its geocentric distance was 3.53 AU. Sixteen images were taken through the F675W filter, and all of them revealed a point-like source without any detectable coma. From these images, we derived the R magnitude of the nucleus in the Johnson-Kron-Cousins photometric system for the entire 11.5-h time span of the observations. Assuming a prolate spheroid whose spin axis lies close to the plane of the sky, the partial lightcurve indicates semi-axes a = 3.9 km and b = 2.8 km (assuming a geometric albedo of 0.04 for the R band and a phase coefficient of 0.04 mag deg(-1)) and a rotational period in the range of similar to25-33 h. The upper limit of the parameter Afrho, which characterizes the dust production rate, is I cm. We also derive a fractional active area at 1.78 AU of similar to4%. (C) 2001 Elsevier Science (USA). C1 CNRS, Astron Spatiale Lab, F-13376 Marseille 12, France. Konkoly Observ Budapest, H-1525 Budapest, Hungary. CNRS, Astron Spatiale Lab, F-13376 Marseille 12, France. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Lamy, PL (reprint author), CNRS, Astron Spatiale Lab, BP 8, F-13376 Marseille 12, France. RI Weaver, Harold/D-9188-2016 NR 27 TC 25 Z9 25 U1 0 U2 2 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2001 VL 154 IS 2 BP 337 EP 344 DI 10.1006/icar.2001.6705 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ZC UT WOS:000175016200010 ER PT J AU Gerakines, PA Moore, MH AF Gerakines, PA Moore, MH TI Carbon suboxide in astrophysical ice analogs SO ICARUS LA English DT Article DE ices; comets; composition; radiation chemistry; photochemistry; spectroscopy ID COMET HALLEY; INTERSTELLAR ICES; DARK CLOUD; SOLID CO; MIXTURES; P/HALLEY; DIOXIDE; VAPOR; ACID; BAND AB As suggested by W. T. Huntress et al. (1991, Nature 352, 316318), carbon suboxide (C3O2) is a potential extended source of both the CO and atomic carbon emission observed in cometary comae. However, laboratory experiments on the formation and stability of C3O2 in space environments have not been published. In this work, we study solid C3O2 in ices representative of cometary nuclei as well as interstellar icy grain mantles, specifically addressing the issues Of C3O2 formation and stability under exposure to energetic processing in the forms of proton irradiation and UV photolysis. The formation rate Of C3O2 is measured in laboratory ices of pure CO and CO2 and mixtures of these molecules with H2O at 18 K. Destruction rates in H2O-dominated mixtures appropriate to a cometary nucleus or interstellar icy grain mantle are also measured. Differences in rates between photolysis and irradiation experiments are observed and quantified. Mid-infrared spectra Of C3O2-containing mixtures are presented together with measurements of carbon suboxide's infrared band strengths and vapor pressures from 110 to 125 K. Implications are discussed for the existence Of C3O2 under the energetic conditions found in astrophysical environments as well as the possibility for its detection in cometary and/or interstellar ices. (C) 2001 Elsevier Science (USA). C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. RP Gerakines, PA (reprint author), Univ Alabama, Dept Phys, Astro & Solar Syst Phys Program, 1300 Univ Blvd, Birmingham, AL 35294 USA. RI Gerakines, Perry/B-9705-2009; Gerakines, Perry/D-2226-2012 OI Gerakines, Perry/0000-0002-9667-5904 NR 40 TC 52 Z9 52 U1 0 U2 3 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2001 VL 154 IS 2 BP 372 EP 380 DI 10.1006/icar.2001.6711 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ZC UT WOS:000175016200013 ER PT J AU Lissauer, JJ Quintana, EV Rivera, EJ Duncan, MJ AF Lissauer, JJ Quintana, EV Rivera, EJ Duncan, MJ TI The effect of a planet in the asteroid belt on the orbital stability SO ICARUS LA English DT Article DE Solar System dynamics; extrasolar planets ID SYSTEM; INTEGRATOR; BEHAVIOR; CHAOS AB If a planetary-mass body were present in the asteroid belt, the orbits of the terrestrial planets and those of the giant planets would be more closely coupled. A greater exchange of angular momentum could affect the stability of the terrestrial planets. Moreover, the planet in the asteroid belt could itself excite terrestrial planet eccentricities. To study these effects, we have simulated several systems consisting of the Solar System planets and a 0.1-10 Earth mass (M-circle plus) object on the orbit of a main belt asteroid or on an initially circular orbit at Ceres's semimajor axis. An integration with Ceres at 5 M-circle plus remained stable for a billion years. Ceres at 10 M-circle plus, however, caused the system to become unstable at similar to25-50 myr. When additional mass was given to both Ceres (bringing it up to 2 M-circle plus) and Mars (1 M-circle plus), the systems self-destructed in <100 myr. However, if these bodies were grown at an epoch when Mars' eccentricity was small, the resulting system was stable for the entire 500 myr simulated. Analogous results were found when other asteroids were grown to planetary masses. Thus, an "asteroid gap" is not required for a planetary system similar to our own to be stable on geological timescales. (C) 2001 Elsevier Science (USA). C1 NASA, Ames Res Ctr, Space Sci Div 245 3, Moffett Field, CA 94035 USA. Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA. SUNY Stony Brook, Dept Astron, Stony Brook, NY 10794 USA. Queens Univ, Dept Phys, Kingston, ON K7L 3N6, Canada. RP Lissauer, JJ (reprint author), NASA, Ames Res Ctr, Space Sci Div 245 3, Moffett Field, CA 94035 USA. NR 16 TC 7 Z9 6 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2001 VL 154 IS 2 BP 449 EP 458 DI 10.1006/icar.2001.6692 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ZC UT WOS:000175016200019 ER PT J AU Ricca, A Bauschlicher, CW Bakes, ELO AF Ricca, A Bauschlicher, CW Bakes, ELO TI A computational study of the mechanisms for the incorporation of a nitrogen atom into polycyclic aromatic hydrocarbons in the Titan haze SO ICARUS LA English DT Article DE Titan; stratospheric chemistry; aromatics ID PHOTOCHEMISTRY; ATMOSPHERE; ACETYLENE; FLAMES; CYANOACETYLENE; DIACETYLENE; CHEMISTRY; JUPITER; MODEL; NM AB Current photochemical models of Titan, Saturn's largest satellite, include chemical reactions producing molecules composed of up to six carbon atoms and then extrapolate straight to aerosols, such as tholins. Laboratory evidence suggests that polycyclic aromatic hydrocarbons containing nitrogen atoms are formed during simulations of Titan's atmosphere. This paper presents preliminary work on reactions that produce nitrogenated aromatic molecules containing up to 12 nonhydrogen atoms. These species would help bridge the gap between the small molecules and the aerosols in Titan's stratosphere. We have determined the barriers and reaction energies for the incorporation of nitrogen into the rings of polycyclic aromatic hydrocarbons. The presence of a nitrogen atom increases the barrier heights relative to the pure hydrocarbon species to about 15 kcal/mol. Nitrogen in the ring promotes the formation of additional hydrocarbon rings by lowering the ring closing barrier to about 4 kcal/mol. Inclusion of these species in photochemical models of Titan is indicated. (C) 2001 Elsevier Science (USA). C1 NASA, Ames Res Ctr, ELORET, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Ricca, A (reprint author), NASA, Ames Res Ctr, ELORET, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 38 TC 58 Z9 59 U1 0 U2 10 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2001 VL 154 IS 2 BP 516 EP 521 DI 10.1006/icar.2001.6694 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ZC UT WOS:000175016200024 ER PT J AU Anicich, VG McEwan, MJ AF Anicich, VG McEwan, MJ TI Termolecular ion-molecule reactions in Titan's atmosphere SO ICARUS LA English DT Article ID GAS-PHASE; CLUSTERING REACTIONS; ASSOCIATION REACTIONS; N-2-CH4 MIXTURES; CH4; STABILITIES; EQUILIBRIA; N-2; IONOSPHERE; HCNH+ AB We have applied information from the thermochemistry of cluster ions to a model of the Titan atmosphere. Using laboratory thermodynamic data on the clustering of ions with both nitrogen and methane from the literature, we find that substantial clustering of ions with the nitrogen atmosphere occurs from about 100 km down to the surface. The temperature and number density profiles of the various chemical species in the atmosphere of Titan were also taken from the literature. A specific analysis of the clustering of HCNH+ with nitrogen was performed. It was found that for HCNH+ substantial clustering will occur in a nitrogen atmosphere at the temperatures and pressures found in the Titan tropopause. The thermochemical data of the three ions: HCNH+, N2H+, and CH5+ are very simular. By inference the N2H+ and CH5+ ions are also expected to undergo substantial clustering. Assuming no factors other than equilibrium thermodynamics to control the cluster size, the maximum average cluster size found was 65.5 at the tropopause. At the surface, the cluster size decreased to about 25. (C) 2001 Elsevier Science (USA). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Canterbury, Dept Chem, Christchurch 1, New Zealand. RP Anicich, VG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 39 TC 8 Z9 8 U1 1 U2 4 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2001 VL 154 IS 2 BP 522 EP 530 DI 10.1006/icar.2001.6696 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ZC UT WOS:000175016200025 ER PT J AU Crawford, RL Paszczynski, A Lang, QY Cheng, IF Barnes, B Anderson, TJ Wells, R Wai, C Corti, G Allenbach, L Erwin, DP Park, J Assefi, T Mojarradi, M AF Crawford, RL Paszczynski, A Lang, QY Cheng, IF Barnes, B Anderson, TJ Wells, R Wai, C Corti, G Allenbach, L Erwin, DP Park, J Assefi, T Mojarradi, M TI In search of the molecules of life SO ICARUS LA English DT Article DE exobiology; instrumentation; organic chemistry ID MARTIAN METEORITE ALH84001; EXTRATERRESTRIAL ORGANIC-MATTER; AMINO-ACIDS; TEMPERATURE ORIGIN; MARS; ATMOSPHERE; ISOTOPES; TITAN; MODEL; PHOTOSYNTHESIS AB The remote detection of a chemical signature of extraterrestrial life ideally requires a broad and nonEarth-centric definition of life. Thus, our proposed approach to detection is based on fundamental thermodynamic assumptions, and some assumptions of how life might obtain energy from its environment. Life, defined as the ability to self-perpetuate, requires a continual input of energy and information. The energy must be tapped in controlled oxidation-reduction reactions between electron donors and acceptors along an electron transport chain. Therefore, the core chemical components of such electron transport chains should be detectable as a signature of life. On Earth, such core structures are principally molecules resembling the porphyrins, quinones, flavins, and nicotinamides (e.g., photosynthetic or respiratory pigments, redox enzymes, and cytochromes). Similar redox-active molecules, perhaps with different structures, might be associated with extraterrestrial life. To validate an approach based on redox signature, signature chemicals were extracted from soil and analyzed by different methods and equipment that may eventually form an integrated "laboratory on a chip" to be used on other planets or their moons. Its components are a supercritical fluid or solvent extraction module, a separation module, and a detection module with an electrochemical detector and electrospray tandem mass-spectrometer. (C) 2001 Elsevier Science (USA). C1 Univ Idaho, Dept Chem, Moscow, ID 83844 USA. Univ Idaho, Environm Biol Inst, Moscow, ID 83844 USA. Univ Idaho, Dept Elect Engn, Moscow, ID 83844 USA. Univ Idaho, Microelect Res & Commun Inst, Moscow, ID 83844 USA. Univ Idaho, Dept Mech Engn, Moscow, ID 83844 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Crawford, RL (reprint author), Univ Idaho, Environm Biol Inst, Moscow, ID 83844 USA. NR 49 TC 11 Z9 12 U1 1 U2 8 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2001 VL 154 IS 2 BP 531 EP 539 DI 10.1006/icar.2001.6714 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 541ZC UT WOS:000175016200026 ER PT J AU Dorsky, LI AF Dorsky, LI TI Trends in instrument systems for deep space exploration SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB In recent years there have been an increasing number of! space science instruments that are being designed as integral elements in integrated instrument suites as, opposed to stand-alone instruments. In fact, some instruments are becoming closely integrated with the mobility systems that carry them to their science targets. This higher level of integration has been motivated by both resource limitations and by an increased focus in: science investigations. The reduced size and budget available for individual space science missions combined with the increased complexity of these missions, has encouraged instrument developers to greater integration to reduce mass, volume, and power needs. In parallel, NASA has shifted focus from flyby and planetary orbiting missions, which primarily, included remote-sensing instruments, to various types of landed vehicles, which include primarily; in-situ instruments. Initial studies of the planets on planetary scales have moved to more detailed ground truth studies on planetary surfaces. The science goals have shifted to focus on specific questions, in the case of Mars, understanding the history of water and the possibilities for life on the planet This increased science focus has, in turn, created the need for integrated science suites that can address these questions in ways that stand-alone instruments cannot. This paper discusses a number of NASA instrument suites, ranging from those currently operating in space to those that are in early study phases. The focus of the, discussion is on the trends, including the shift to greater integration, the concomitant challenges that must be overcome to achieve this integration and the benefits that can ensue. This is not intended to be a comprehensive examination of new instrument suites (that would be a much longer paper) rather, the example NASA instrument suites discussed were selected, from those that the author had some familiarity with, to include suites representative of the trends in instrument systems for deep space exploration. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Dorsky, LI (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 1 Z9 1 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD DEC PY 2001 VL 16 IS 12 BP 3 EP 12 DI 10.1109/62.974833 PG 10 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA 509MB UT WOS:000173150600002 ER PT J AU Leung, K Shell, D Ivancic, WD Stewart, DH Bell, TL Kachmar, BA AF Leung, K Shell, D Ivancic, WD Stewart, DH Bell, TL Kachmar, BA TI Application of mobile-IP to space and aeronautical networks SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB NASA is interested in applying Mobile Internet Protocol (mobile-ip) technologies to its space and aeronautics programs. In particular, mobile-ip will play a major role in the Advanced Aeronautic Transportation Technology (AATT), the Weather Information Communication (WINCOMM) and the Small Aircraft Transportation System (SATS) aeronautics programs. This, paper describes mobile-ip and mobile-routers - in particular, the features, capabilities, and initial performance of the mobile-router is presented. The application of mobile-router technology to NASA's space and aeronautics programs is also discussed. C1 Cisco Syst, San Jose, CA 95134 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Verizon, Cleveland, OH 44135 USA. Lockheed Martin Global Telecommun, Cleveland, OH 44135 USA. Analex Corp, Brookpark, OH 44142 USA. RP Leung, K (reprint author), Cisco Syst, 170 W Tasman Dr, San Jose, CA 95134 USA. NR 1 TC 10 Z9 11 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD DEC PY 2001 VL 16 IS 12 BP 13 EP 18 DI 10.1109/62.974834 PG 6 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA 509MB UT WOS:000173150600003 ER PT J AU Howard, A Seraji, H AF Howard, A Seraji, H TI An intelligent terrain-based navigation system for planetary rovers SO IEEE ROBOTICS & AUTOMATION MAGAZINE LA English DT Article DE mobile robots; navigation; fuzzy logic; neural networks AB A Fuzzy Logic Framework for Onboard Terrain Analysis and Guidance Towards Traversable Regions. C1 NASA, JPL, Washington, DC 20546 USA. RP Howard, A (reprint author), CALTECH, Jet Prop Lab, Mail Stop 198-219, Pasadena, CA 91109 USA. NR 7 TC 17 Z9 20 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1070-9932 J9 IEEE ROBOT AUTOM MAG JI IEEE Robot. Autom. Mag. PD DEC PY 2001 VL 8 IS 4 BP 9 EP 17 DI 10.1109/100.973242 PG 9 WC Automation & Control Systems; Robotics SC Automation & Control Systems; Robotics GA 506TU UT WOS:000172988500003 ER PT J AU Dobbins, JA Rogers, RL AF Dobbins, JA Rogers, RL TI Folded conical helix antenna SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article DE conical antennas; folded antennas; helix antennas AB A novel conical monopole antenna composed of multiple spiral wires for the HF to VHF frequency bands is presented. The antenna exhibits broad bandwidth and good efficiency in an electrically small package. Broadbanding and impedance matching techniques used during the design process of this antenna are described. Measured data from a VHF version of this antenna is shown. The performance of this antenna is then compared to the performance of other electrically small antennas. C1 NASA, Johnson Space Ctr, Houston, TX 78758 USA. Univ Texas, Austin, TX 78128 USA. RP Dobbins, JA (reprint author), NASA, Johnson Space Ctr, Houston, TX 78758 USA. NR 13 TC 24 Z9 24 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD DEC PY 2001 VL 49 IS 12 BP 1777 EP 1781 DI 10.1109/8.982460 PG 5 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 520CE UT WOS:000173762000026 ER PT J AU Yueh, SH Stiles, BW Tsai, WY Hu, H Liu, WT AF Yueh, SH Stiles, BW Tsai, WY Hu, H Liu, WT TI QuikSCAT geophysical model function for tropical cyclones and application to hurricane floyd SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE radar; remote sensing; sea surface; wind ID HIGH-WIND CONDITIONS; OCEAN BACKSCATTER; KU-BAND; SURFACE; LANDFALL; FIELDS; ALGORITHM; SYSTEM AB The QuikSCAT radar measurements of several tropical cyclones in 1999 have been studied to develop the geophysical model function (GMF) of Ku-band radar sigma(0)s for extreme high wind conditions. To account for the effects of precipitation, we analyze the co-located rain rates from the Special Sensor Microwave/Imager (SSM/I) and propose the rain rate as a parameter of the GMF The analysis indicates the deficiency of the NSCAT2 GMF developed for the NASA scatterometer, which overestimates the ocean sigma(0) for tropical cyclones and ignores the influence of rain. It is suggested that the QuikSCAT sigma(0) is sensitive to the wind speed of up to about 40-50 m.s(-1). We introduce modifications to the NSCAT2 GMF and apply the modified GMF to the QuikSCAT observations of Hurricane Floyd. The QuikSCAT wind estimates for Hurricane Floyd in 1999 was improved with the maximum wind speed reaching above 60 m/s. We perform an error analysis by comparing the QuikSCAT winds with the analyses fields from the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division (HRD). The reasonable agreement between the improved QuikSCAT winds and the HRD analyses supports the applications of scatterometer wind retrievals for hurricanes. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yueh, SH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 27 TC 29 Z9 32 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD DEC PY 2001 VL 39 IS 12 BP 2601 EP 2612 DI 10.1109/36.974995 PG 12 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 511ZK UT WOS:000173296500004 ER PT J AU Xapsos, MA AF Xapsos, MA TI 2001 Special Nuclear and Space Radiation Effects Conference (NSREC) Issue of the IEEE Transactions on Nuclear Science SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Editorial Material C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Xapsos, MA (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1749 EP 1749 AR PII S0018-9499(01)10542-3 DI 10.1109/TNS.2001.983120 PN 1 PG 1 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300001 ER PT J AU Johnston, AH Miyahira, TF Rax, BG AF Johnston, AH Miyahira, TF Rax, BG TI Proton damage in advanced laser diodes SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE laser diodes; proton damage; radiation effects ID QUANTUM-WELL LASERS; SURFACE-EMITTING LASERS; GAIN; RECOMBINATION; IRRADIATION AB \Proton radiation damage in laser diodes is investigated for several types of laser diodes with wavelengths from 650 to 1550 mu. Key parameters include slope efficiency, threshold current, and the transition characteristics between laser-emitting diode (LED) and laser operation. Some of the devices exhibited nonlinear relationships between threshold current and proton fluence. All of the lasers, including vertical-cavity surface-emitting lasers, were strongly affected by recombination-enhanced annealing, in contrast to double-heterojunction LEDs, which are only slightly affected by annealing. Analysis of laser characteristics after irradiation showed that the main effect of radiation damage is an increase in bulk recombination that increases loss within the laser cavity. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnston, AH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 28 TC 20 Z9 28 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1764 EP 1772 AR PII S0018-9499(01)10534-4 DI 10.1109/23.983128 PN 1 PG 9 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300004 ER PT J AU Eid, ES Chan, TY Fossum, ER Tsai, RH Spagnuolo, R Deily, J Byers, WB Peden, JC AF Eid, ES Chan, TY Fossum, ER Tsai, RH Spagnuolo, R Deily, J Byers, WB Peden, JC TI Design and characterization of ionizing radiation-tolerant CMOS APS image sensors up to 30 Mrd (Si) total dose SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE active pixel sensor; CMOS active pixel sensor; CMOS APS; dark current; image sensor; imager; ionizing radiation; ionizing radiation-induced dark current; ionizing radiation-tolerant CMOS APS; radiation hard; radiation tolerant ID ON-A-CHIP; CAMERA AB An ionizing radiation-tolerant CMOS active pixel sensor (APS) image sensor test chip was designed employing the physical design techniques of enclosed geometry and P-channel guard rings. The test chip was fabricated in a standard 0.35-mum CMOS process that has a gate-oxide thickness of 7.0 nm. It was irradiated by a gamma-ray source up to a total ionizing radiation dose level of approximately 30 Mrd (Si) and was still functional. The most pronounced effect was the increase of dark current, which was linear with total dose level. The rate of dark current increase was about 1 to 2 pA/cm(2)/Krd (Si), depending on the design of the pixel. The results demonstrate that CMOS APS image sensors can be designed to be ionizing radiation tolerant to total dose levels up to 30 Mrd (Si). The fabrication process is standard CMOS, yielding a significant cost advantage over specialized radiation hard processes. C1 Photobit Technol Corp, Pasadena, CA 91101 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Applicat Int Corp, Mclean, VA 22102 USA. RP Eid, ES (reprint author), Photobit Technol Corp, Pasadena, CA 91101 USA. NR 35 TC 42 Z9 43 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1796 EP 1806 AR PII S0018-9499(01)10529-0 DI 10.1109/23.983133 PN 1 PG 11 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300009 ER PT J AU Waczynski, A Polidan, EJ Marshall, PW Reed, RA Johnson, SD Hill, RJ Delo, GS Wassell, EJ Cheng, ES AF Waczynski, A Polidan, EJ Marshall, PW Reed, RA Johnson, SD Hill, RJ Delo, GS Wassell, EJ Cheng, ES TI A comparison of charge transfer efficiency measurement techniques on proton damaged n-channel CCDs for the Hubble Space Telescope wide-field camera 3 SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE CTE; CTE noise; EEPR; EEV; FPR; minichannel; proton radiation damage; radiation testing; SBC; scientific CCD; WFC3 AB We examine proton-damaged charge-coupled devices (CCDs) and compare the charge transfer efficiency (CTE) degradation using extended pixel edge response, first pixel response, and Fe-55 X-ray measurements. CTEs measured on Marconi and Fairchild imaging sensors CCDs degrade similarly at all signal levels, though some of the Fairchild CCDs had a supplementary buried channel. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20770 USA. NASA, Goddard Space Flight Ctr, Brookneal, VA 24528 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Waczynski, A (reprint author), Dorsal Networks, Columbia, MD 21046 USA. NR 15 TC 22 Z9 25 U1 1 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1807 EP 1814 AR PII S0018-9499(01)10528-9 DI 10.1109/23.983134 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300010 ER PT J AU Swift, GM Farmanesh, FF Guertin, SM Irom, F Millward, DG AF Swift, GM Farmanesh, FF Guertin, SM Irom, F Millward, DG TI Single-event upset in the PowerPC750 microprocessor SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE fault diagnosis; heavy ions; microprocessor; protons; radiation effects; single-event effects (SEEs); single-event upset (SEU) ID SEU AB Proton and heavy ion upset susceptibility has been measured individually for six types of storage elements in an advanced commercial processor, the PowerPC750, from two manufacturers: Motorola and IBM. Data on interfering program malfunctions was also collected. Compared to earlier PPC603e results, the upset susceptibility has decreased somewhat. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Millward Res, San Diego, CA 92128 USA. RP Swift, GM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 25 Z9 26 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1822 EP 1827 AR PII S0018-9499(01)10526-5 DI 10.1109/23.983136 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300012 ER PT J AU Heidergott, WF Ladbury, R Marshall, PW Buchner, S Campbell, AB Reed, RA Hockmuth, J Kha, N Hammond, C Seidleck, C Assad, A AF Heidergott, WF Ladbury, R Marshall, PW Buchner, S Campbell, AB Reed, RA Hockmuth, J Kha, N Hammond, C Seidleck, C Assad, A TI Complex SEU signatures in high-speed analog-to-digital conversion SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE analog-to-digital conversion; ion radiation effects; proton radiation effects ID INTEGRATED-CIRCUITS; CONVERTERS AB The complex single-event upset (SEU) signatures produced by high-speed analog-to-digital converter devices are analyzed to establish magnitude, duration, and pattern characteristics. Histograms and other descriptive summaries of event characteristics are identified and their use in performing system effects analysis is described. C1 Motorola Inc, Scottsdale, AZ 85252 USA. NRL, Brookneal, VA 24528 USA. SFA Inc, Largo, MD 20774 USA. USN, Res Lab, Washington, DC 20275 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Heidergott, WF (reprint author), Motorola Inc, Scottsdale, AZ 85252 USA. NR 6 TC 4 Z9 4 U1 2 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1828 EP 1832 AR PII S0018-9499(01)10525-3 DI 10.1109/23.983138 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300013 ER PT J AU Miyahira, TF Johnston, AH Becker, HN LaLumondiere, SD Moss, SC AF Miyahira, TF Johnston, AH Becker, HN LaLumondiere, SD Moss, SC TI Catastrophic latchup in CMOS analog-to-digital converters SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE analog-to-digital converters (ADCs); latchup; radiation effects ID DEVICES; TEMPERATURE; SIMULATION AB Heavy-ion latchup is investigated for analog-to-digital converters. Differences in cross section for various ions show that charge is collected at depths beyond 50 mum, causing the cross section to be underestimated unless long-range ions are used. Current distributions, thermal imaging, and diagnostic tests with a pulsed laser were used to identify latchup-sensitive regions. Latchup in one of the circuit types was catastrophic, even when the power was turned off within 2 ms of a latchup event. Examination of damaged devices with a scanning electron microscope showed that the failures occurred in metallization and contact regions. Current density for failure agrees with pulsed current metallization stress data in the literature. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Aerosp Corp, Los Angeles, CA 90009 USA. RP Miyahira, TF (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 17 TC 12 Z9 15 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1833 EP 1840 AR PII S0018-9499(01)10524-1 DI 10.1109/23.983139 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300014 ER PT J AU Crain, SH Mazur, JE Katz, RB Koga, R Looper, MD Lorentzen, KR AF Crain, SH Mazur, JE Katz, RB Koga, R Looper, MD Lorentzen, KR TI Analog and digital single-event effects experiments in space SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE antifuse rupture; comparator; COTS; electron dose enhancement; field-programmable gate array (FPGA); flight experiment; ground test; heavy ion radiation; MPTB; operational amplifier; proton irradiation; radiation effects; single-event effect (SEE); single-event transient (SET); single-event upset (SEU); spot shielding; test bed; total ionizing dose (TID) ID RADIATION AB Field-programmable gate arrays (FPGAs) and operational amplifiers are commonly used microelectronics in spaceflight instrumentation. In ground-based testing, these devices have been shown to experience single-event upset (SEU), the digital variety for the FPGA and the analog or transient type for the op-amps. Two experiment boards on the Microelectronics and Photonics Test Bed (MPTB) test these same parts in space. The data collected to date are presented here. The most interesting results are not from the primary focus of the SEU but from the total ionizing dose (TID) current monitoring of the FPGAs. C1 Aerosp Corp, El Segundo, CA 90245 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Crain, SH (reprint author), Aerosp Corp, El Segundo, CA 90245 USA. NR 10 TC 9 Z9 9 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1841 EP 1848 AR PII S0018-9499(01)10523-X DI 10.1109/23.983140 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300015 ER PT J AU Niu, GF Krithivasan, R Cressler, JD Marshall, P Marshall, C Reed, R Harame, DL AF Niu, GF Krithivasan, R Cressler, JD Marshall, P Marshall, C Reed, R Harame, DL TI Modeling of single-event effects in circuit-hardened high-speed SiGe HBT logic SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE charge collection; circuit modeling; current-mode logic; heterojunction bipolar transistor (HBT); SiGe; single-event effects (SEEs) ID CHARGE COLLECTION; SIMULATION; UPSET AB This paper presents single-event effect (SEE) modeling results of circuit-hardened SiGe heterojunction bipolar transistor logic circuits. A simple equivalent circuit is proposed to model the ion-induced currents at all of the terminals, including the p-type substrate. The SEE sensitivity of a D-flip-flop was simulated using the proposed equivalent circuit. The simulation results are qualitatively consistent with earlier SEE testing results. The circuit upset is shown to be independent of the number of active paths. Considerable charge collection occurs through the reverse-biased n-collector/p-substrate junction, regardless of the status of the emitter steering current, resulting in circuit upset through the commonly connected load resistor. A heavily doped substrate is shown to be beneficial for SEE. C1 Auburn Univ, Dept Elect & Comp Engn, Auburn, AL 36849 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. IBM Microelect, Essex Jct, VT 05401 USA. RP Niu, GF (reprint author), Auburn Univ, Dept Elect & Comp Engn, Auburn, AL 36849 USA. EM guofu@eng.auburn.edu RI Krithivasan, Ramkumar/D-3549-2011 NR 8 TC 22 Z9 22 U1 3 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1849 EP 1854 AR PII S0018-9499(01)10522-8 DI 10.1109/23.983141 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300016 ER PT J AU Lum, GK Robinette, L Howard, A AF Lum, GK Robinette, L Howard, A TI The use of proton testing for evaluating COTS: Example of a commercial camera for ISS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE accelerators; aerospace testing; cameras; charge coupled devices; cyclotron radiation; integrated radiation circuit effects; proton radiation effects; radiation effects; radiation hardening; semiconductor radiation effects ID INDUCED SEE; HEAVY-ION; UPSET; PARTS; OPTOCOUPLERS; IRRADIATION; LATCHUP AB With the increasing demand for high performance and lower cost, commercial off-the-shelf (COTS) parts are being applied to many space applications. Because certain products have a large quantity of COTS devices, testing them individually can become cost prohibitive and complex. Proton testing provides such a compromise. Depending on the space environment and the application, proton testing can be a cost effective technique for evaluating parts. This paper presents some of the advantages and disadvantages in considering tradeoffs between protons versus heavy ion testing. Such a case is discussed of using a commercial video controller and CCD for a LEO system such as the International Space Station where COTS are heavily being considered. Possible risk mitigating steps are suggested to reduce the possibility of a catastrophic failure. C1 Lockheed Martin Space Syst Co, Sunnyvale, CA 94088 USA. NASA, LMSSC, Ames Res Ctr, Mt View, CA 94040 USA. RP Lum, GK (reprint author), Lockheed Martin Space Syst Co, Sunnyvale, CA 94088 USA. NR 36 TC 2 Z9 2 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1885 EP 1892 AR PII S 0018-9499(01)10666-0 DI 10.1109/23.983147 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300022 ER PT J AU Conley, JF Suehle, JS Johnston, AH Wang, B Miyahara, T Vogel, EM Bernstein, JB AF Conley, JF Suehle, JS Johnston, AH Wang, B Miyahara, T Vogel, EM Bernstein, JB TI Heavy-ion-induced soft breakdown of thin gate oxides SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE dielectric breakdown; gate oxide; heavy ions; microelectronics; MOS; radiation; SiO2 ID INDUCED LEAKAGE CURRENT; IRRADIATION; RUPTURE AB Heavy-ion-induced soft and hard breakdown are investigated in thin gate oxides as a function of linear energy transfer, fluence, and voltage applied during irradiation. It is found that postirradiation oxide conduction is well described by the Sune quantum point contact model. C1 CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91109 USA. NIST, Div Semicond Elect, Gaithersburg, MD 20899 USA. Univ Maryland, Ctr Reliabil Engn, College Pk, MD 20742 USA. RP Conley, JF (reprint author), CALTECH, Jet Prop Lab, NASA, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Vogel, Eric/A-7731-2008 OI Vogel, Eric/0000-0002-6110-1361 NR 17 TC 27 Z9 27 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1913 EP 1916 AR PII S 0018-9499(01)10669-6 DI 10.1109/23.983150 PN 1 PG 4 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300025 ER PT J AU Edmonds, LD Guertin, SM Scheick, LZ Nguyen, D Swift, GM AF Edmonds, LD Guertin, SM Scheick, LZ Nguyen, D Swift, GM TI Ion-induced stuck bits in 1T/1C SDRAM cells SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE microdose; stuck bit cross sections; stuck bit rates; stuck bits ID SINGLE HARD ERRORS; SRAMS AB Radiation exposure of certain types of devices tends to stick bits, causing them to not be read out correctly after programming. Evidence of a linear trend in stuck bits in SDRAM memory cells is presented. This trend makes a cross section, as traditionally defined for single-event effects, unambiguous. However, there are considerable part-to-part variations in the cross section. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Edmonds, LD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 25 Z9 26 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 1925 EP 1930 AR PII S0018-9499(01)10671-4 DI 10.1109/23.983152 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300027 ER PT J AU Jun, I McAlpine, W AF Jun, I McAlpine, W TI Displacement damage in silicon due to secondary neutrons, pions, deuterons, and alphas from proton interactions with materials SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE displacement damage; nonionizing energy loss; proton; secondary particles AB The enhancement of displacement damage energy deposition due to secondary neutrons, pions, deuterons, and alphas resulting from high-energy (100-1000 MeV) proton interactions with aluminum and tungsten shielding are examined in this paper. The results obtained using a comprehensive Monte Carlo charged particle transport code, MCNPX Version 2.1.5, indicated that the dominant secondary particle is neutrons. The additional contribution to the displacement damage energy produced by secondary pious, deuterons, and alphas turned out to be less than 5%. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jun, I (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 5 Z9 6 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 2034 EP 2038 AR PII S0018-9499(01)10687-8 DI 10.1109/23.983168 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300043 ER PT J AU McNulty, PJ Scheick, LZ Yow, S Campbell, AB Savage, MW AF McNulty, PJ Scheick, LZ Yow, S Campbell, AB Savage, MW TI Single-chip dosimeters to accompany photometric systems flown in space SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE AB Modern photometer systems need to be accompanied by dosimeters that monitor exposure to total ionizing dose, ultraviolet light, and the flux of particles with linear energy transfer above some threshold value. These detectors should minimize space, weight, power, cost, and telemetry. A new approach is described in which single-chip, two-chip, or three-chips systems incorporated into the photometer's interface circuits measure the above while including information on the status of charge trapping in oxides and thermal noise at p-n junctions. C1 Clemson Univ, Dept Phys & Astron, Clemson, SC 29634 USA. Jet Prop Lab, Elect Parts Engn Dept, Pasadena, CA 91101 USA. USN, Res Lab, Washington, DC 20375 USA. RP McNulty, PJ (reprint author), Clemson Univ, Dept Phys & Astron, Clemson, SC 29634 USA. NR 9 TC 2 Z9 2 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 2039 EP 2042 AR PII S0018-9499(01)10688-X DI 10.1109/23.983169 PN 1 PG 4 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300044 ER PT J AU Li, Y Niu, GF Cressler, JD Patel, J Marshall, CJ Marshall, PW Kim, HS Reed, RA Palmer, MJ AF Li, Y Niu, GF Cressler, JD Patel, J Marshall, CJ Marshall, PW Kim, HS Reed, RA Palmer, MJ TI Anomalous radiation effects in fully depleted SOI MOSFETs fabricated on SIMOX SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE fully depleted; H-gate; kink; proton; radiation; self-annealing; SIMOX; SOI MOSFETs AB We investigate the proton tolerance of fully depleted silicon-on-insulator (SOI) MOSFETs with H-gate and regular-gate structural configurations. For the front-gate characteristics, the H-gate does not show the edge leakage observed in the regular-gate transistor. An anomalous kink in the back-gate linear I-D-V-GS characteristics of the fully depleted SOI nFETs has been observed at high radiation doses. This kink is attributed to charged traps generated in the bandgap at the buried oxide/silicon film interface during irradiation. Extensive two-dimensional simulations with MEDICI were used to understand the physical origin of this kink. We also report unusual self-annealing effects in the devices when they are cooled to liquid nitrogen temperature. C1 Auburn Univ, Alabama Microelect Sci & Technol Ctr, Dept Elect & Comp Engn, Auburn, AL 36849 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Jackson & Tull Chartered Engineers, Washington, DC 20018 USA. RP Li, Y (reprint author), Auburn Univ, Alabama Microelect Sci & Technol Ctr, Dept Elect & Comp Engn, Auburn, AL 36849 USA. NR 16 TC 6 Z9 7 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 2146 EP 2151 AR PII S0018-9499(01)10658-1 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300062 ER PT J AU Poivey, C Howard, JW Buchner, S LaBel, KA Forney, JD Kim, HS Assad, A AF Poivey, C Howard, JW Buchner, S LaBel, KA Forney, JD Kim, HS Assad, A TI Development of a test methodology for single-event transients (SETs) in linear devices SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE bipolar analog integrated circuits; comparators; integrated circuits; ion radiation effects; laser radiation effects; linear circuits; operational amplifiers; radiation effects ID INTEGRATED-CIRCUITS; ANALOG AB We present single-event transient (SET) test data on linear devices under many operational conditions in an attempt to understand the SET generation and characteristics. This is done in an attempt to define a low-cost conservative test methodology to characterize these effects. C1 Jackson & Tull, Seabrook, MD 20706 USA. SGT Inc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SFA Inc, Largo, MD USA. USN, Res Lab, Washington, DC 20375 USA. RP Poivey, C (reprint author), SGT Inc, Greenbelt, MD 20771 USA. NR 9 TC 13 Z9 14 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 2180 EP 2186 AR PII S0018-9499(01)10709-4 DI 10.1109/23.983193 PN 1 PG 7 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300068 ER PT J AU Reed, RA Poivey, C Marshall, PW LaBel, KA Marshall, CJ Kniffin, S Barth, JL Seidleck, C AF Reed, RA Poivey, C Marshall, PW LaBel, KA Marshall, CJ Kniffin, S Barth, JL Seidleck, C TI Assessing the impact of the space radiation environment on parametric degradation and single-event transients in optocouplers SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE displacement damage; hardness assurance; optocouplers; single-event effects (SEEs); total ionizing dose ID ENERGY-DEPENDENCE; PROTON; DAMAGE; UPSET AB Assessing the risk of using optocouplers in satellite applications offers challenges that incorporate those of commercial off-the-shelf devices compounded by hybrid module construction techniques. We discuss approaches for estimating this risk. In the process, we benchmark our estimates for proton and heavy-ion induced single-event transient rate estimates with recent flight data from the Terra mission. For parametric degradation, we discuss a method for acquiring test data and mapping it into an estimation approach that captures all the important variables of circuit application, environment, damage energy dependence, complex response to total ionizing dose and displacement effects, temperature, and annealing. C1 NASA, Goddard Space Flight Ctr, SGT Inc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Orbital Sci, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Raytheon Corp, Greenbelt, MD 20771 USA. RP Reed, RA (reprint author), NASA, Goddard Space Flight Ctr, SGT Inc, Greenbelt, MD 20771 USA. NR 18 TC 14 Z9 17 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 2202 EP 2209 AR PII S0018-9499(01)10712-4 DI 10.1109/23.983196 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300071 ER PT J AU Zhang, SM Niu, GF Cressler, JD Osten, HJ Knoll, D Marshall, CJ Marshall, PW Kim, HS Reed, RA AF Zhang, SM Niu, GF Cressler, JD Osten, HJ Knoll, D Marshall, CJ Marshall, PW Kim, HS Reed, RA TI The effects of proton irradiation on SiGe : CHBTs SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE neutral base recombination; proton irradiation; SiGe : C heterojunction bipolar transistor (HBTs). ID IONIZING-RADIATION AB The effects of 63-MeV proton irradiation on SiGe:C heterojunction bipolar transistors (HBTs) are reported for the first time. The de characteristics and neutral base recombination of these SiGe: C HBTs are investigated for proton fluences up to 5 x 10(13) p/cm(2). A comparison is made with SiGe HBTs fabricated in the same technology. Despite the fact that these SiGe:C HBTs degrade significantly during proton exposure, there is no indication that the carbon doping has any significant impact on the radiation response. C1 Auburn Univ, Dept Elect & Comp Engn, Alabama Microelect Sci & Technol Ctr, Auburn, AL 36849 USA. Inst Semicond Phys, D-15236 Frankfurt, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Jackson & Tull Chartered Engineers, Washington, DC 20018 USA. RP Zhang, SM (reprint author), Auburn Univ, Dept Elect & Comp Engn, Alabama Microelect Sci & Technol Ctr, Auburn, AL 36849 USA. NR 12 TC 11 Z9 11 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 2233 EP 2237 AR PII S0018-9499(01)10717-3 DI 10.1109/23.983201 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300076 ER PT J AU Cressler, JD Hamilton, MC Krithivasan, R Ainspan, H Groves, R Niu, GF Zhang, SM Jin, ZR Marshall, CJ Marshall, PW Kim, HS Reed, RA Palmer, MJ Joseph, AJ Harame, DL AF Cressler, JD Hamilton, MC Krithivasan, R Ainspan, H Groves, R Niu, GF Zhang, SM Jin, ZR Marshall, CJ Marshall, PW Kim, HS Reed, RA Palmer, MJ Joseph, AJ Harame, DL TI Proton radiation response of SiGe HBT analog and RF circuits and passives SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE bipolar transistor; circuits; heterojunction bipolar transistor (HBT); passives; silicon germanium (SiGe) ID PERFORMANCE; TECHNOLOGY; TOLERANCE; UHV/CVD; BICMOS AB We present the first experimental results of the effects of 63-MeV proton irradiation on SiGe heterojunction bipolar transistor (HBT) analog and radio-frequency (RF) circuits and passive elements. A SiGe HBT bandgap reference circuit, commonly used to generate stable on-chip voltages in analog ICs, a SiGe HBT voltage-controlled oscillator, a key building block for RE transceivers, and an LC bandpass filter routinely used in RF circuit design were each irradiated to proton fluences as high as 5 x 10(13) p/cm(2). The degradation associated with these extreme proton fluences was found to be minimal, suggesting that SiGe HBT technology is robust for these types of circuit applications. C1 Auburn Univ, Dept Elect & Comp Engn, Alabama Microelect Sci & Technol Ctr, Auburn, AL 36849 USA. IBM Corp, Div Res, Thomas J Watson Res Ctr, Yorktown Hts, NY 10598 USA. IBM Microelect, Fishkill, NY 12533 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Jackson & tull Chartered Engineers, Washington, DC 20018 USA. IBM Microelect, Essex Jct, VT 05452 USA. RP Cressler, JD (reprint author), Auburn Univ, Dept Elect & Comp Engn, Alabama Microelect Sci & Technol Ctr, Auburn, AL 36849 USA. NR 17 TC 21 Z9 22 U1 1 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 2238 EP 2243 AR PII S0018-9499(01)10718-5 DI 10.1109/23.983202 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300077 ER PT J AU Jin, ZR Niu, GF Cressler, JD Marshall, CJ Marshall, PW Kim, HS Reed, RA Harame, DL AF Jin, ZR Niu, GF Cressler, JD Marshall, CJ Marshall, PW Kim, HS Reed, RA Harame, DL TI 1/f noise in proton-irradiated SiGeHBTs SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 38th Annual Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 16-20, 2001 CL VANCOUVER, CANADA SP IEEE DE 1/f noise; proton irradiation; SiGe heterojunction bipolar transistor (HBT) ID LOW-FREQUENCY NOISE; BIPOLAR JUNCTION TRANSISTORS; TECHNOLOGY; LOCATION; SI AB This paper investigates the impact of proton irradiation on the 1/f noise in ultra-high-voltage chemical-vapor deposition SiGe heterojunction bipolar transistors. The relative degradation of 1/f noise shows a strong dependence on device geometry. Both the geometry dependence and the bias dependence of 1/f noise change significantly after exposure to 2 x 10(13) p/cm(2) protons. An expression describing the 1/f noise is derived and used to explain the experimental observations. C1 Auburn Univ, Dept Elect & Comp Engn, Auburn, AL 36849 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Jackson & Tull Chartered Engineers, Washington, DC 20018 USA. IBM Microelect, Essex Jct, VT 05401 USA. RP Jin, ZR (reprint author), Auburn Univ, Dept Elect & Comp Engn, Auburn, AL 36849 USA. NR 23 TC 22 Z9 22 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2001 VL 48 IS 6 BP 2244 EP 2249 AR PII S0018-9449(01)10765-3 DI 10.1109/23.983203 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 521UT UT WOS:000173860300078 ER PT J AU Das, SK Harvey, DJ Biswas, R AF Das, SK Harvey, DJ Biswas, R TI Parallel processing of adaptive meshes with load balancing SO IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS LA English DT Article DE dynamic load balancing; experimental study; IBM SP2; job migration and redistribution; symmetric broadcast networks; unstructured mesh adaptation ID UNSTRUCTURED MESHES AB Many scientific applications involve grids that lack a uniform underlying structure. These applications are often also dynamic in nature in that the grid structure significantly changes between successive phases of execution. In parallel computing environments, mesh adaptation of unstructured grids through selective refinement/coarsening has proven to be an effective approach. However, achieving load balance while minimizing interprocessor communication and redistribution costs is a difficult problem. Traditional dynamic load balancers are mostly inadequate because they lack a global view of system loads across processors. In this paper, we propose a novel and general-purpose load balancer that utilizes symmetric broadcast networks (SBN) as the underlying communication topology and compare its performance with a successful global load balancing environment, called, PLUM, specifically created to handle adaptive unstructured applications. Our experimental results on an IBM SP2 demonstrate that the SBN-based load balancer achieves lower redistribution costs than that under PLUM by overlapping processing and data migration. C1 Univ Texas, Dept Comp Sci & Engn, Arlington, TX 76019 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Univ Texas, Dept Comp Sci & Engn, Arlington, TX 76019 USA. EM das@cse.uta.edu; harvey@cse.uta.edu; rbiswas@nas.nasa.gov NR 21 TC 32 Z9 33 U1 0 U2 2 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1045-9219 EI 1558-2183 J9 IEEE T PARALL DISTR JI IEEE Trans. Parallel Distrib. Syst. PD DEC PY 2001 VL 12 IS 12 BP 1269 EP 1280 DI 10.1109/71.970562 PG 12 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 501UQ UT WOS:000172704800005 ER PT J AU Trebi-Ollennu, A Huntsberger, T Cheng, Y Baumgartner, ET Kennedy, B Schenker, P AF Trebi-Ollennu, A Huntsberger, T Cheng, Y Baumgartner, ET Kennedy, B Schenker, P TI Design and analysis of a sun sensor for planetary rover absolute heading detection SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article DE celestial navigation; heading detection; planetary rovers; rover localization; state estimation AB This paper describes a new sun sensor for absolute heading detection developed for the Field Integrated, Design and Operations (FIDO) rover. The FIDO rover is an advanced technology rover that is a terrestrial prototype of the rovers NASA/Jet Propulsion Laboratory (JPL) plans to send to Mars in 2003. Our goal was to develop a sun sensor that fills the current cost/performance gap, uses the power of subpixel interpolation, makes use of current hardware on the rover, and demands very little computational overhead. The need for a sun sensor on planetary rovers lies in the fact that current means of estimating the heading of planetary rovers involves integration of noisy rotational-speed measurements. This noise causes error to accumulate and grow rapidly. Moreover, the heading error affects the estimate of the x and y position of the rover. More importantly, incremental odometry heading estimation is only reliable over relatively short distances. There is an urgent need to develop a new heading-detection sensor for long traverses [for example, 100 in per Sol (Martian Day)], as requested for future Mars mission. Results of a recent FIDO field trial at Black Rock Summit in Central Nevada and several operations readiness tests at the JPL MarsYard using the sun sensor have demonstrated threefold to fourfold improvement in the heading estimation of the rover compared to incremental odometry. C1 CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, NASA, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM ashitey@jpl.nasa.gov NR 19 TC 30 Z9 33 U1 1 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD DEC PY 2001 VL 17 IS 6 BP 939 EP 947 DI 10.1109/70.976028 PG 9 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA 512RP UT WOS:000173337600018 ER PT J AU Yamada, H Yamaguchi, Y Kim, Y Rodriguez, E Boerner, WM AF Yamada, H Yamaguchi, Y Kim, Y Rodriguez, E Boerner, WM TI Polarimetric SAR interferometry for forest analysis based on the ESPRIT algorithm SO IEICE TRANSACTIONS ON ELECTRONICS LA English DT Article DE synthetic aperture radar; interferometry; polarimetry; vegetation; ESPRIT algorithm ID RADAR INTERFEROMETRY AB Synthetic aperture radar interferometry have been established in the past two decades, and used extensively for many applications including topographic mapping of terrain and surface deformation. Vegetation analysis is also a growing area of its application. In this paper, we propose an polarimetric SAP, interferometry technique for interferometric phase extraction of each local scatterer. The estimated position of local scattering centers has an important information fur effective tree height estimation of forest. The proposed method formulated for local scattering center extraction is based on the ESPRIT algorithm which is known for high-resolution capability of closely located incident waves. The method shows high-resolution performance when local scattered waves are. uncorrelated and have different polarization characteristics, Using the method. the number of dominant local scattering centers and interferometric phases in each image pixel can be estimated directly. Validity of the algorithm is demonstrated by using examples derived from SIR-C data. C1 Niigata Univ, Dept Informat Engn, Niigata 9202181, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Illinois, Chicago, IL 60607 USA. RP Yamada, H (reprint author), Niigata Univ, Dept Informat Engn, Niigata 9202181, Japan. EM yamada@ie.niigata-u.ac.jp NR 17 TC 24 Z9 35 U1 1 U2 4 PU IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG PI TOKYO PA KIKAI-SHINKO-KAIKAN BLDG, 3-5-8, SHIBA-KOEN, MINATO-KU, TOKYO, 105-0011, JAPAN SN 0916-8524 EI 1745-1353 J9 IEICE T ELECTRON JI IEICE Trans. Electron. PD DEC PY 2001 VL E84C IS 12 BP 1917 EP 1924 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA 504UQ UT WOS:000172874600031 ER PT J AU Rumsey, CL Gatski, TB Anderson, WK Nielsen, EJ AF Rumsey, CL Gatski, TB Anderson, WK Nielsen, EJ TI Isolating curvature effects in computing wall-bounded turbulent flows SO INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW LA English DT Article DE streamline curvature; turbulence models; zero pressure gradient; design optimization; explicit algebraic stress ID EQUATIONS; DESIGN; MODELS; LAYERS AB An adjoint optimization method is utilized to design an inviscid outer wall shape required for a turbulent flow field solution of the So-Mellor convex curved wall experiment using the Navier-Stokes equations. The associated cost function is the desired pressure distribution on the inner wall. Using this optimized wall shape with a Navier-Stokes method, the abilities of various turbulence models to simulate the effects of curvature without the complicating factor of streamwise pressure gradient are evaluated. The one-equation Spalart-Allmaras (SA) turbulence model overpredicts eddy viscosity, and its boundary layer profiles are too full. A curvature-corrected version of this model improves results, which are sensitive to the choice of a particular constant. An explicit algebraic stress model does a reasonable job predicting this flow field. However, results can be slightly improved by modifying the assumption on anisotropy equilibrium in the model's derivation. The resulting curvature-corrected explicit algebraic stress model (EASM) possesses no heuristic functions or additional constants. It slightly lowers the computed skin friction coefficient and the turbulent stress levels for this case, in better agreement with experiment. The effect on computed velocity profiles is minimal. (C) 2001 Elsevier Science Inc. All rights reserved. C1 NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. RP Rumsey, CL (reprint author), NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Mail Stop 128, Hampton, VA 23681 USA. NR 20 TC 9 Z9 9 U1 2 U2 5 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0142-727X J9 INT J HEAT FLUID FL JI Int. J. Heat Fluid Flow PD DEC PY 2001 VL 22 IS 6 BP 573 EP 582 DI 10.1016/S0142-727X(01)00122-9 PG 10 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA 488ZR UT WOS:000171967700001 ER PT J AU Garg, VK Ameri, AA AF Garg, VK Ameri, AA TI Two-equation turbulence models for prediction of heat transfer on a transonic turbine blade SO INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW LA English DT Article DE turbulence modeling; heat transfer; turbine blade; turbulence length scale; turbulence production ID REYNOLDS-NUMBER; 2-EQUATION AB Two versions of the two-equation k-omega model and a shear stress transport (SST) model are used in a three-dimensional, multiblock, Navier-Stokes code to compare the detailed heat transfer measurements on a transonic turbine blade. It is found that the SST model resolves the passage vortex better on the suction side of the blade, thus yielding a better comparison with the experimental data than either of the k-omega models. However, the comparison is still deficient on the suction side of the blade. Use of the SST model does require the computation of distance from a wall, which for a multi-block grid, such as in the present case, can be complicated. However, a relatively easy fix for this problem was devised. Also addressed are issues such as (1) computation of the production term in the turbulence equations for aerodynamic applications, and (2) the relation between the computational and experimental values for the turbulence length scale, and its influence on the passage vortex on the suction side of the turbine blade. (C) 2001 Elsevier Science Inc. All rights reserved. C1 NASA, Glenn Res Ctr, AYT Res Corp, Cleveland, OH 44135 USA. RP Garg, VK (reprint author), NASA, Glenn Res Ctr, AYT Res Corp, Mail Stop 5-11,21000 Brook Pk Rd, Cleveland, OH 44135 USA. NR 18 TC 20 Z9 24 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0142-727X J9 INT J HEAT FLUID FL JI Int. J. Heat Fluid Flow PD DEC PY 2001 VL 22 IS 6 BP 593 EP 602 DI 10.1016/S0142-727X(01)00128-X PG 10 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA 488ZR UT WOS:000171967700003 ER PT J AU Bernhard, RP Christiansen, EL Kerr, JH AF Bernhard, RP Christiansen, EL Kerr, JH TI Space Shuttle meteoroid and orbital debris impact damage SO INTERNATIONAL JOURNAL OF IMPACT ENGINEERING LA English DT Article; Proceedings Paper CT Symposium on Hypervelocity Impact CY NOV 06-10, 2000 CL GALVESTON, TX DE orbital debris; meteoroid; space shuttle; hypervelocity impact damage; impactors AB Post-flight surveys of meteoroid and orbital debris (M&OD) impacts on the Space Shuttle Orbiter are conducted to identify damage caused by hypervelocity impacts from M&OD and to identify the source (i.e., whether meteoroid or orbital debris) of the projectiles responsible [1,2] This report provides data on Orbiter M&OD impacts for a five-year period and describes in detail the 39 most significant impacts. For the period 6/92 through 12/99 there were 49 Shuttle Transportation System (STS) missions (STS-50 through STS-103) of which 38 had post-flight inspections to identify M&OD impacts. Approximately 10% of the vehicle is surveyed in the M/OD inspections. The data for the 39 most significant impacts based on size found during the inspections are summarized in Table 1. This work contains estimates of impactor size which were determined using appropriate impact damage penetration equations that were derived by hypervelocity impact (HVI) test and analysis on relevant Orbiter materials. Although predictions for numbers of impacts are produced for each STS mission, we do not compare those predictions to the actual damage reported here as further efforts must be made to analyze the as-flown attitude timeline and adjust the predicted damage accordingly. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Lockheed Martin, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Lockheed Martin, Houston, TX 77058 USA. NR 5 TC 4 Z9 7 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0734-743X EI 1879-3509 J9 INT J IMPACT ENG JI Int. J. Impact Eng. PD DEC PY 2001 VL 26 IS 1-10 BP 33 EP 38 DI 10.1016/S0734-743X(01)00073-2 PG 6 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 510ZN UT WOS:000173237600006 ER PT J AU Bernhard, RP Horz, F See, TH Warren, JL AF Bernhard, RP Horz, F See, TH Warren, JL TI Soft capture of earth-orbiting hypervelocity particles with aerogel SO INTERNATIONAL JOURNAL OF IMPACT ENGINEERING LA English DT Article; Proceedings Paper CT Symposium on Hypervelocity Impact CY NOV 06-10, 2000 CL GALVESTON, TEXAS DE aerogel; orbital debris; micrometeoroid; Mir space station; impactors ID INTACT AB The Orbital Debris Collection (ODC) experiment exposed similar to 0.6 m(2) of SiO2-based aerogel (0.02 g/cm(3)) for 18 months on the US Docking Module of the Mir space station. Post-flight inspection revealed hundreds of millimeter-sized hypervelocity features, ranging from deep penetration tracks to rather shallow pits. Intermediate morphologies suggest that deep tracks and shallow pits are the end members of a morphological continuum that seems controlled by impact velocity. Some 163 particles were recovered from the termini of deep tracks. Scanning (SEM) and Transmission Electron Microscopy (TEM) suggest that shock and thermal alterations are minimal and that individual phases and their textures are well preserved. SEM investigations combined with Energy Dispersive X-Ray Spectroscopy (EDS) reveal a wide variety of natural and man-made particle types, akin to those from other space-exposed surfaces. Very shallow aerogel depressions contain human-waste products. The transparent pits, similar to 20% of all hypervelocity features, contain no residues detectable with SEM-EDS methods, suggesting that the utility of aerogel to soft capture hypervelocity impactors is velocity-limited. This velocity threshold is estimated at similar to 18-20 km/s for the ODC aerogel. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Lockheed Martin Space Operat, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch, Houston, TX 77058 USA. RP Bernhard, RP (reprint author), Lockheed Martin Space Operat, C23,2400 NASA Rd 1, Houston, TX 77058 USA. NR 21 TC 2 Z9 2 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0734-743X J9 INT J IMPACT ENG JI Int. J. Impact Eng. PD DEC PY 2001 VL 26 IS 1-10 BP 39 EP 51 DI 10.1016/S0734-743X(01)00076-8 PG 13 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 510ZN UT WOS:000173237600007 ER PT J AU Christiansen, EL Kerr, JH AF Christiansen, EL Kerr, JH TI Ballistic limit equations for spacecraft shielding SO INTERNATIONAL JOURNAL OF IMPACT ENGINEERING LA English DT Article; Proceedings Paper CT Symposium on Hypervelocity Impact CY NOV 06-10, 2000 CL GALVESTON, TEXAS DE shielding; meteoroid/orbital debris protection; ballistic limit equations ID DEBRIS AB This paper provides equations describing the ballistic performance capability of meteoroid/orbital debris (M/OD) shield systems employed on the International Space Station (ISS). Hypervelocity impact (HVI) tests and analysis were used in developing the semiempirical ballistic limit equations (BLE). A description of each type of shield system, HVI tests and analysis performed to assess shield performance, and ballistic limit equations that define the protection capability of the shield are given. Methods to improve the performance of spacecraft shielding are also discussed. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Christiansen, EL (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SN3, Houston, TX 77058 USA. NR 10 TC 44 Z9 76 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0734-743X J9 INT J IMPACT ENG JI Int. J. Impact Eng. PD DEC PY 2001 VL 26 IS 1-10 BP 93 EP 104 DI 10.1016/S0734-743X(01)00070-7 PG 12 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 510ZN UT WOS:000173237600011 ER PT J AU Hyde, JL Christiansen, EL Kerr, JH AF Hyde, JL Christiansen, EL Kerr, JH TI Meteoroid and orbital debris risk mitigation in a low earth orbit satellite constellation SO INTERNATIONAL JOURNAL OF IMPACT ENGINEERING LA English DT Article; Proceedings Paper CT Symposium on Hypervelocity Impact CY NOV 06-10, 2000 CL GALVESTON, TEXAS DE bumper; orbital debris; PNP AB The NASA/JSC Hypervelocity Impact Technology Facility (HITF) performed a meteoroid and orbital debris threat assessment on a low earth orbit satellite constellation. The results of the analysis will show that the risk from hypervelocity impact was significant enough to warrant design changes. The techniques used to significantly mitigate the risk from hypervelocity impact will be discussed. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Lockheed Martin Space Operat, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Hyde, JL (reprint author), NASA, Lockheed Martin Space Operat, Lyndon B Johnson Space Ctr, Bldg 267,C23C, Houston, TX 77058 USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0734-743X J9 INT J IMPACT ENG JI Int. J. Impact Eng. PD DEC PY 2001 VL 26 IS 1-10 BP 345 EP 356 DI 10.1016/S0734-743X(01)00104-X PG 12 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 510ZN UT WOS:000173237600033 ER PT J AU Lamontagne, CG Manuelpillai, GN Kerr, JH Taylor, EA Tennyson, RC Burchell, MJ AF Lamontagne, CG Manuelpillai, GN Kerr, JH Taylor, EA Tennyson, RC Burchell, MJ TI Projectile density, impact angle and energy effects on hypervelocity impact damage to carbon fibre/peek composites SO INTERNATIONAL JOURNAL OF IMPACT ENGINEERING LA English DT Article; Proceedings Paper CT Symposium on Hypervelocity Impact CY NOV 06-10, 2000 CL GALVESTON, TEXAS DE hypervelocity impact; composites; density; oblique angle; energy; debris clouds; cone angle; damage AB This paper explores the effects of projectile density, impact angle and energy on the damage produced by hypervelocity impacts on carbon fibre/PEEK composites. Tests were performed using the light gas gun facilities at the University of Kent at Canterbury, UK, and the NASA Johnson Space Center two-stage light gas gun facilities at Rice University in Houston, Texas. Various density spherical projectiles impacted AS4/PEEK composite laminates at velocities ranging from 2.71 to 7.14 km/s. In addition, a series of tests with constant size aluminum projectiles (1.5 mm in diameter) impacting composite targets at velocities of 3,4, 5 and 6 km/s was undertaken at incident angles of 0, 30 and 45 degrees. Similar tests were also performed with 2 mm aluminum projectiles impacting at a velocity of approximately 6 km/s. The damage to the composite was shown to be independent of projectile density; however, debris cloud damage patterns varied with particle density. It was also found that the entry crater diameters were more dependent upon the impact velocity and the projectile diameter than the impact angle. The extent of the primary damage on the witness plates for the normal incidence impacts was shown to increase with impact velocity, hence energy. A series of tests exploring the shielding effect on the witness plate showed that a stand-off layer of Nextel fabric was very effective at breaking up the impacting debris cloud, with the level of protection increasing with a non-zero stand-off distance, (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Toronto, Inst Aerosp Studies, Downsview, ON M3H 5T6, Canada. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Kent, Unit Space Sci & Astrophys, Canterbury CT2 7NR, Kent, England. RP Lamontagne, CG (reprint author), Univ Toronto, Inst Aerosp Studies, 4925 Dufferin St, Downsview, ON M3H 5T6, Canada. OI Burchell, Mark/0000-0002-2680-8943 NR 17 TC 15 Z9 16 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0734-743X J9 INT J IMPACT ENG JI Int. J. Impact Eng. PD DEC PY 2001 VL 26 IS 1-10 BP 381 EP 398 DI 10.1016/S0734-743X(01)00110-5 PG 18 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 510ZN UT WOS:000173237600036 ER PT J AU Olsen, GD Nolen, AM AF Olsen, GD Nolen, AM TI Hypervelocity impact testing of pressure vessels to simulate spacecraft failure SO INTERNATIONAL JOURNAL OF IMPACT ENGINEERING LA English DT Article; Proceedings Paper CT Symposium on Hypervelocity Impact CY NOV 06-10, 2000 CL GALVESTON, TEXAS DE hypervelocity impact; impact testing; pressure vessels AB A series of hypervelocity impact tests are conducted against thin-walled aluminum pressure vessels to investigate failure mechanisms. The vessels, 0.05 and 0.08 inches thick, are constructed to replicate the material properties of the International Space Station (ISS). The vessels are pressurized to simulate the conditions experienced by the habitable modules of the ISS. A test matrix incorporating shielded thin plates, shielded vessels under no pressure and shielded vessels under internal pressure is developed to take advantage of knowledge gained in earlier tests. Given the design parameters of the ISS coupled with the capabilities of light gas gun testing, it is shown that a catastrophic failure due to unzipping is unlikely. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 ITT Ind, Adv Engn & Sci Div, Huntsville, AL 35802 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Olsen, GD (reprint author), ITT Ind, Adv Engn & Sci Div, 600 Blvd South,Suite 208, Huntsville, AL 35802 USA. NR 15 TC 8 Z9 8 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0734-743X J9 INT J IMPACT ENG JI Int. J. Impact Eng. PD DEC PY 2001 VL 26 IS 1-10 BP 555 EP 566 DI 10.1016/S0734-743X(01)00113-0 PG 12 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 510ZN UT WOS:000173237600051 ER PT J AU Sokolov, VG Christiansen, EL Gorbenko, AV Feldstein, VA Romanchenkov, VP Panichkin, NG Yachlakov, YV Zinchenko, LV AF Sokolov, VG Christiansen, EL Gorbenko, AV Feldstein, VA Romanchenkov, VP Panichkin, NG Yachlakov, YV Zinchenko, LV TI The effect of thin deployable construction elements of the International Space Station on the probability of its hull penetration by meteoroids and orbital debris SO INTERNATIONAL JOURNAL OF IMPACT ENGINEERING LA English DT Article; Proceedings Paper CT Symposium on Hypervelocity Impact CY NOV 06-10, 2000 CL GALVESTON, TEXAS DE meteoroid; debris; collision; shield; impact; probability; penetration; fragmentation; ballistic limit curve; shadowing AB When calculating the probability of hull penetration by meteoroid and orbital debris (M/OD) for some of the International Space Station (ISS) modules (e.g. FGB, Service module, cargo vehicle "Progress"), one has to take into account their additional shielding produced by ISS deployable construction elements (such as solar panels, radiators), which decrease M/OD penetrating probabilities. The lack of developed calculation methods of accounting for this effect has arisen the necessity to investigate the law- governed nature of particle fragmentation process accompanying high velocity penetration of thin barriers, as well as to elaborate techniques for correct calculation of the probability of no penetration (PNP) of module pressure wall. The results of thorough analysis of the theoretical and experime ntal published data as well as of data obtained in joint NASA and RSA experimental program on particle fragmentation are presented in this report in the form of normalized analytical correlation between the fragment maximum size and impact parameters. On the basis of above mentioned particle fragmentation law, the method of module hull ballistic limit curves (BLC's) recalculation is determined, which include the effect of thin barriers greatly distanced from the module hull. This BLC's are used for module PNP calculations with the help of modified version of NASA BUMPER code. The special subroutines accounting for PNP changes due to the particle collisions with ISS deployable construction elements are introduced in the BUMPER algorithm. The results of the Service module PNP calculations with account for its "shadowing" by solar panels and radiators are presented. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Rocket & Space Corp Energia, Moscow, Russia. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RSA, TZNIIMASH, Moscow, Russia. RP Sokolov, VG (reprint author), Rocket & Space Corp Energia, Moscow, Russia. NR 3 TC 2 Z9 2 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0734-743X J9 INT J IMPACT ENG JI Int. J. Impact Eng. PD DEC PY 2001 VL 26 IS 1-10 BP 725 EP 734 DI 10.1016/S0734-743X(01)00120-8 PG 10 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 510ZN UT WOS:000173237600065 ER PT J AU Lathouwers, D Bellan, J AF Lathouwers, D Bellan, J TI Modeling of dense gas-solid reactive mixtures applied to biomass pyrolysis in a fluidized bed SO INTERNATIONAL JOURNAL OF MULTIPHASE FLOW LA English DT Article ID VISCOUS RELAXATION-TIME; GRANULAR-MATERIALS; KINETIC-THEORY; CONSTITUTIVE RELATIONS; SPHERICAL-PARTICLES; FLASH PYROLYSIS; COLLISION TIME; HEAT-TRANSFER; FLOWS; SPHERES AB A model is presented for mathematically describing the thermofluid dynamics of dense, reactive, gas-solid mixtures. The model distinguishes among multiple particle classes, either on the basis of their physical properties (diameter, density) or through their thermochemistry (reactive versus inert particles). A multifluid approach is followed where macroscopic equations are derived from the kinetic theory of granular flows using inelastic rigid-sphere models, thereby accounting for collisional transfer in high-density regions. Separate transport equations are constructed for each of the particle classes, allowing for the description of the independent acceleration of the particles in each class and the interaction between size classes, as well as for the equilibration processes whereby momentum and energy are exchanged between the respective classes and the carrier gas. Aimed at high-density suspensions, such as fluidized beds, the relations obtained for the stress tensor are augmented by a model for frictional transfer, suitably extended to multiple-class systems. This model, previously derived, is here enlarged to include heat and mass transfer, as well as chemical reactions and is therefore applicable to general gas-solid combustion systems. The noteworthy novelties of the model with respect to other derivations in the literature include: (i) a systematic and consistent derivation of the solids transport equations and transport properties within the multifluid concept, allowing for non-equilibrium effects between the respective particle classes, (ii) the ability to explicitly account for the possibility of porous solid fuel particles, and (iii) the modeling of multiple chemical reactions in both gas and solid phases and the associated effects of heat and mass transfer. The model, which includes a separately validated chemistry model, is applied to high-temperature biomass particle pyrolysis in a lab-scale fluidized bed reactor and is used to obtain yield of reaction products. The results indicate that, at fixed initial particle size, the fluidizing gas temperature is the foremost parameter influencing tar yield. The biomass feed temperature, the nature of the feedstock, and the fluidization velocity all have minor impact on the yield. It is also shown that the fluidizing gas temperature can be optimized for maximizing the tar yield. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Appl Technol Sect, Pasadena, CA 91109 USA. RP Bellan, J (reprint author), CALTECH, Jet Prop Lab, Appl Technol Sect, 4800 Oak Grove Dr,Mail Stn 125-109, Pasadena, CA 91109 USA. NR 44 TC 53 Z9 55 U1 1 U2 13 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0301-9322 J9 INT J MULTIPHAS FLOW JI Int. J. Multiph. Flow PD DEC PY 2001 VL 27 IS 12 BP 2155 EP 2187 DI 10.1016/S0301-9322(01)00059-3 PG 33 WC Mechanics SC Mechanics GA 497BA UT WOS:000172431800007 ER PT J AU Kreinovich, V Starks, SA AF Kreinovich, V Starks, SA TI Aerospace applications of intervals: From geospatial data processing to fault detection in aerospace structures SO INTERNATIONAL JOURNAL OF UNCERTAINTY FUZZINESS AND KNOWLEDGE-BASED SYSTEMS LA English DT Article; Proceedings Paper CT 1st International Conference on Intelligent Technologies (InTech 2000) CY 2000 CL BANGKOK, THAILAND DE interval computations; aerospace applications AB This paper presents a brief introduction into interval computations and their use in aerospace applications. C1 Univ Texas, El Paso, TX 79968 USA. NASA, Pan Amer Ctr Earth & Environm Studies, El Paso, TX 79968 USA. RP Kreinovich, V (reprint author), Univ Texas, 500 W Univ Ave, El Paso, TX 79968 USA. NR 8 TC 0 Z9 0 U1 0 U2 1 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 912805, SINGAPORE SN 0218-4885 J9 INT J UNCERTAIN FUZZ JI Int. J. Uncertainty Fuzziness Knowl.-Based Syst. PD DEC PY 2001 VL 9 IS 6 BP 721 EP 730 PG 10 WC Computer Science, Artificial Intelligence SC Computer Science GA 532CU UT WOS:000174454700007 ER PT J AU Lipshitz, R Klein, G Orasanu, J Salas, E AF Lipshitz, R Klein, G Orasanu, J Salas, E TI Focus article: Taking stock of naturalistic decision making SO JOURNAL OF BEHAVIORAL DECISION MAKING LA English DT Review DE naturalistic decision making; recognition-primed decisions; coping with uncertainty; team decision making; decision errors; decision training; research methodology ID COGNITIVE TASK-ANALYSIS; ELICITING KNOWLEDGE; PHYSICS PROBLEMS; PERFORMANCE; JUDGMENT; EXPERTS; CHOICE; UNCERTAINTY; SIMULATION; AWARENESS AB We review the progress of naturalistic decision making (NDM) in the decade since the first conference on the subject in 1989. After setting out a brief history of NDM we identify its essential characteristics and consider five of its main contributions: recognition-primed decisions, coping with uncertainty team decision making, decision errors, and methodology. NDM helped identify important areas of inquiry previously neglected (e.g. the use of expertise in sizing up situations and generating options), it introduced new models, conceptualizations, and methods, and recruited applied investigators into the field. Above all, NDM contributed a new perspective on how decisions (broadly defined as committing oneself to a certain course of action) are made. NDM still faces significant challenges, including improvement of the quantity and rigor of its empirical research, and confirming the validity of its prescriptive models. Copyright (C) 2001 John Wiley & Sons, Ltd. C1 Univ Haifa, Dept Psychol, IL-31905 Haifa, Israel. NASA, Ames, IA USA. Univ Cent Florida, Orlando, FL 32816 USA. RP Lipshitz, R (reprint author), Univ Haifa, Dept Psychol, IL-31905 Haifa, Israel. EM raanan@psy.haifa.ac.il NR 110 TC 237 Z9 238 U1 8 U2 54 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0894-3257 J9 J BEHAV DECIS MAKING JI J. Behav. Decis. Mak. PD DEC PY 2001 VL 14 IS 5 BP 331 EP 352 DI 10.1002/bdm.381 PG 22 WC Psychology, Applied SC Psychology GA 505VD UT WOS:000172935500002 ER PT J AU Lipshitz, R Klein, G Orasanu, J Salas, E AF Lipshitz, R Klein, G Orasanu, J Salas, E TI Rejoinder: A welcome dialogue - and the need to continue SO JOURNAL OF BEHAVIORAL DECISION MAKING LA English DT Editorial Material C1 Univ Haifa, Dept Psychol, IL-31905 Haifa, Israel. NASA, Ames, IA USA. Univ Cent Florida, Orlando, FL 32816 USA. RP Lipshitz, R (reprint author), Univ Haifa, Dept Psychol, IL-31905 Haifa, Israel. EM raanan@psy.haifa.ac.il NR 18 TC 7 Z9 7 U1 1 U2 2 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0894-3257 J9 J BEHAV DECIS MAKING JI J. Behav. Decis. Mak. PD DEC PY 2001 VL 14 IS 5 BP 385 EP 389 DI 10.1002/bdm.398 PG 5 WC Psychology, Applied SC Psychology GA 505VD UT WOS:000172935500019 ER PT J AU Whelan, HT Smits, RL Buchman, EV Whelan, NT Turner, SG Margolis, DA Cevenini, V Stinson, H Ignatius, R Martin, T Cwiklinski, J Philippi, AF Graf, WR Hodgson, B Gould, L Kane, M Chen, G Caviness, J AF Whelan, HT Smits, RL Buchman, EV Whelan, NT Turner, SG Margolis, DA Cevenini, V Stinson, H Ignatius, R Martin, T Cwiklinski, J Philippi, AF Graf, WR Hodgson, B Gould, L Kane, M Chen, G Caviness, J TI Effect of NASA light-emitting diode irradiation on wound healing SO JOURNAL OF CLINICAL LASER MEDICINE & SURGERY LA English DT Article ID BONE-MARROW TRANSPLANTATION; ENERGY LASER IRRADIATION; HELIUM-NEON LASER; PHOTODYNAMIC THERAPY; ORAL MUCOSITIS; BRAIN-TUMORS; DOUBLE-BLIND; BIOSTIMULATION; CULTURES; COLLAGEN AB Objective: The purpose of this study was to assess the effects of hyperbaric oxygen (HBO) and near-infrared light therapy on wound healing. Background Data: Light-emitting diodes (LED), originally developed for NASA plant growth experiments in space show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper, we review and present our new data of LED treatment on cells grown in culture, on ischemic and diabetic wounds in rat models, and on acute and chronic wounds in humans. Materials and Methods: In vitro and in vivo (animal and human) studies utilized a variety of LED wavelength, power intensity, and energy density parameters to begin to identify conditions for each biological tissue that are optimal for biostimulation. Results: LED produced in vitro increases of cell growth of 140-200% in mouse-derived fibroblasts, rat-derived osteoblasts, and rat-derived skeletal muscle cells, and increases in growth of 155-171% of normal human epithelial cells. Wound size decreased up to 36% in conjunction with HBO in ischemic rat models. LED produced improvement of greater than 40% in musculoskeletal. training injuries in Navy SEAL team members, and decreased wound healing time in crew members aboard a U.S. Naval submarine. LED produced a 47% reduction in pain of children suffering from oral mucositis. Conclusion: We believe that the use of NASA LED for light therapy alone, and in conjunction with hyperbaric oxygen, will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the NASA Marshall Space Flight Center-SBIR Program. C1 Med Coll Wisconsin, Dept Neurol, Milwaukee, WI 53226 USA. Med Coll Wisconsin, Dept Plast Surg, Milwaukee, WI 53226 USA. Quantum Devices Inc, Barnveld, WI USA. Childrens Hosp Wisconsin, Milwaukee, WI 53201 USA. USMCR, Force Serv Support Grp, Dent Battal 4, Marietta, GA USA. TWO, Naval Special Warfare Grp, Norfolk, VA USA. Submarine Squadron ELEVEN, San Diego, CA USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Whelan, HT (reprint author), Med Coll Wisconsin, Dept Neurol, Milwaukee, WI 53226 USA. NR 35 TC 253 Z9 267 U1 6 U2 46 PU MARY ANN LIEBERT INC PUBL PI LARCHMONT PA 2 MADISON AVENUE, LARCHMONT, NY 10538 USA SN 1044-5471 J9 J CLIN LASER MED SUR JI J. Clin. Laser Med. Sur. PD DEC PY 2001 VL 19 IS 6 BP 305 EP 314 DI 10.1089/104454701753342758 PG 10 WC Engineering, Biomedical; Surgery SC Engineering; Surgery GA 501HK UT WOS:000172679100004 PM 11776448 ER PT J AU Ruthruff, E Remington, RW Johnston, JC AF Ruthruff, E Remington, RW Johnston, JC TI Switching between simple cognitive tasks: The interaction of top-down and bottom-up factors SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Article ID SPEEDED-CHOICE TASKS; REPETITION; ACTIVATION; STIMULUS; COSTS; SET; ATTENTION; MEMORY AB How do top-down factors (e.g., task expectancy) and bottom-up factors (e.g., task recency) interact to produce an overall level of task readiness? This question was addressed by factorially manipulating task expectancy and task repetition in a task-switching paradigm. The effects of expectancy and repetition on response time tended to interact underadditively, but only because the traditional binary task-repetition variable lumps together all switch trials, ignoring variation in task tag. When the task-recency variable was scaled continuously, all 4 experiments instead showed additivity between expectancy and recency. The results indicated that expectancy and recency influence different stages of mental processing. One specific possibility (the configuration-execution model) is that task expectancy affects the time required to configure upcoming central operations, whereas task recency affects the time required to actually execute those central operations. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ruthruff, E (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 33 TC 120 Z9 125 U1 1 U2 6 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 USA SN 0096-1523 J9 J EXP PSYCHOL HUMAN JI J. Exp. Psychol.-Hum. Percept. Perform. PD DEC PY 2001 VL 27 IS 6 BP 1404 EP 1419 DI 10.1037//0096-1523.27.6.1404 PG 16 WC Psychology; Psychology, Experimental SC Psychology GA 498BQ UT WOS:000172490300010 PM 11766933 ER PT J AU Berejikian, BA Tezak, EP Riley, SC LaRae, AL AF Berejikian, BA Tezak, EP Riley, SC LaRae, AL TI Competitive ability and social behaviour of juvenile steelhead reared in enriched and conventional hatchery tanks and a stream environment SO JOURNAL OF FISH BIOLOGY LA English DT Article DE steelhead; competition; territorial behaviour; territory overlap ID SALMON ONCORHYNCHUS-KISUTCH; TERRITORY SIZE; AGONISTIC BEHAVIOR; COHO SALMON; REARING ENVIRONMENTS; WILD POPULATIONS; ATLANTIC SALMON; TROUT; DOMINANCE; MYKISS AB Steelhead Oncorhynchus mykiss fry reared in an enriched hatchery environment (overhead cover, submerged structures and underwater feeders) and a natural stream both achieved significantly greater social dominance ranks than fry reared in a conventional hatchery environment. Dominant fry from enriched tanks and natural stream exhibited greater frequencies of threat displays than dominant fry reared in conventional tanks. Fry reared in the natural stream exhibited greater territory overlap than fry from either hatchery environment. Overall, the results suggest that enriched hatchery environments may act to ameliorate some but not all changes in social behaviour that result from hatchery rearing. C1 Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Resource Enhancement & Utilizat Technol Div, Res Stn, Manchester, WA 98353 USA. Pacific States Marine Fisheries Commiss, Gladstone, OR 97027 USA. RP Berejikian, BA (reprint author), Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Resource Enhancement & Utilizat Technol Div, Res Stn, POB 130, Manchester, WA 98353 USA. EM barry.berejikian@noaa.gov NR 35 TC 45 Z9 45 U1 3 U2 17 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0022-1112 EI 1095-8649 J9 J FISH BIOL JI J. Fish Biol. PD DEC PY 2001 VL 59 IS 6 BP 1600 EP 1613 DI 10.1006/jfbi.2001.1789 PG 14 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 514ZC UT WOS:000173470100015 ER PT J AU Kerr, RB Garcia, R He, X Noto, J Lancaster, RS Tepley, CA Gonzalez, SA Friedman, J Doe, RA Lappen, M McCormack, B AF Kerr, RB Garcia, R He, X Noto, J Lancaster, RS Tepley, CA Gonzalez, SA Friedman, J Doe, RA Lappen, M McCormack, B TI Periodic variations of geocoronal Balmer-alpha brightness due to solar-driven exospheric abundance variations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ATOMIC-HYDROGEN; LINE-PROFILES; LYMAN-BETA; EMISSION; MODELS; EXCITATION; DENSITY; RATES; CYCLE AB Measurements of the geocoronal Balmer-alpha (H-alpha) brightness have been made at the Arecibo Observatory during 11 separate periods since 1983 using both a Fabry-Perot interferometer and a tilting filter photometer. The tilting filter photometer is calibrated for absolute sensitivity using a constant brightness source traceable to National Institute of Standards and Techniques (NIST) standards and is used to cross-calibrate the Fabry-Perot interferometer. Since the observational technique has not changed since 1983, and since the data analyses technique are uniform, these data provide a measure of the solar cycle variation of H-alpha, brightness at Arecibo. Unlike earlier studies, we discern no systematic discrepancy between the H-alpha brightness and estimates of the solar Lyman-beta flux that pumps the resonant fluorescent H-alpha emission. Rather, we conclude that geocoronal hydrogen abundance is generally (but not always) larger than models suggest, although not systematically so. The largest H-alpha emission is measured during solar minimum conditions, when brightness is approximately 50% greater than during solar maximum conditions, for measurements at solar depression angles from 15degrees to 35degrees. Above about 40degrees solar depression (corresponding to an illuminated column with a base at approximately 2000 kin), no solar cycle variation is evident, and the brightness there is persistently greater than models. Intricacies of the Lyman-beta radiative transport problem make detection of an early morning maximum of hydrogen density near the exobase difficult using brightness data alone, although the H-alpha brightness is generally asymmetric with respect to local midnight, with brighter emission in the postmidnight sector. Studies of the semidiurnal (nighttime) variation demonstrate that the H-alpha brightness can vary by a factor of 2 over a period of days. C1 Sci Solut Inc, N Chelmsford, MA 01863 USA. Cornell Univ, Arecibo Observ, Arecibo, PR 00613 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Goddard Earth Sci & Technol Ctr, Mesoscale Atmospher Proc Branch, Greenbelt, MD 20771 USA. SRI Int, Menlo Pk, CA 94025 USA. RP Kerr, RB (reprint author), Sci Solut Inc, 55 Middlesex St,Unit 210, N Chelmsford, MA 01863 USA. RI Gonzalez, Sixto/G-1982-2011; Friedman, Jonathan/E-4985-2011 OI Gonzalez, Sixto/0000-0001-5544-1426; Friedman, Jonathan/0000-0002-9353-2377 NR 46 TC 14 Z9 14 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 28797 EP 28817 DI 10.1029/1999JA900186 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500002 ER PT J AU Kerr, RB Garcia, R He, X Noto, J Lancaster, RS Tepley, CA Gonzalez, SA Friedman, J Doe, RA Lappen, M McCormack, B AF Kerr, RB Garcia, R He, X Noto, J Lancaster, RS Tepley, CA Gonzalez, SA Friedman, J Doe, RA Lappen, M McCormack, B TI Secular variability of the geocoronal Balmer-alpha brightness: magnetic activity and possible human influences SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EXOSPHERIC HYDROGEN DENSITY; ATMOSPHERIC METHANE; SOUTHERN-HEMISPHERE; LINE-PROFILES; EMISSION; EXCITATION; INCREASE; MODELS; RATES AB Measurements of the geocoronal Balmer-alpha (H-alpha) brightness taken between 1983 and 1994 at the Arecibo Observatory (18.35degrees N, 66.75degrees W) occasionally display aperiodic brightness variations that we attribute to a local response of exospheric hydrogen abundance to geomagnetic activity. Approximately twofold H-alpha brightness enhancements in the days following moderate storm onset conditions are demonstrated, and the absolute brightness during these events is significantly greater than modeled brightness based on quiet geomagnetic conditions. Although there are no direct measurements of the line center solar Lyman beta (Ly beta) flux that pumps H-alpha during these events, the magnitude of the brightness enhancements and the temporal reproducibility of the phenomena (following onset of all storms in our data) make it likely that the enhanced H-alpha brightness is due to enhanced column abundances of hydrogen in the exosphere above Arecibo and not to sporadic increases in the solar Ly beta flux. Increased hydrogen abundance due to thermal expansion of the midlatitude atmosphere following propagation of the auroral heating event cannot account for the entire enhancement. The data also suggest that H-alpha brightness has become systematically stronger from 1984 to 1994, independent of solar cycle variability or variations due to geomagnetic activity. An increase of similar to3% per year, may be attributable to real change in the geocoronal hydrogen column abundance during the period, and is possibly a consequence of increasing hydrogenous species concentrations in the lower atmosphere. The enhancement of geocoronal H-alpha brightness between 1984 and 1994 may be the consequence of increasing methane in the troposphere and may signal that the effects of methane deposition in the lower atmosphere have propagated throughout the atmosphere. C1 Sci Solut Inc, N Chelmsford, MA 01863 USA. Cornell Univ, Arecibo Observ, Arecibo, PR 00613 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Goddard Earth Sci & Technol Ctr, Mesoscale Atmospher Proc Branch, Greenbelt, MD 20771 USA. SRI Int, Menlo Pk, CA 94025 USA. RP Kerr, RB (reprint author), Sci Solut Inc, 55 Middlesex St,Unit 210, N Chelmsford, MA 01863 USA. RI Friedman, Jonathan/E-4985-2011; Gonzalez, Sixto/G-1982-2011 OI Friedman, Jonathan/0000-0002-9353-2377; Gonzalez, Sixto/0000-0001-5544-1426 NR 39 TC 9 Z9 9 U1 2 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 28819 EP 28829 DI 10.1029/1999JA900187 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500003 ER PT J AU McAllister, AH Martin, SF Crooker, NU Lepping, RP Fitzenreiter, RJ AF McAllister, AH Martin, SF Crooker, NU Lepping, RP Fitzenreiter, RJ TI A test of real-time prediction of magnetic cloud topology and geomagnetic storm occurrence from solar signatures SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; SOFT X-RAYS; SEMIANNUAL VARIATION; PROMINENCE ERUPTION; FILAMENT ERUPTION; H-ALPHA; 1 AU; ORIGIN; WIND; CME AB On the basis of the location, orientation, and surrounding magnetic field configuration of an erupting filament observed on September 27, 1997, an Earth-encounter with a magnetic cloud having specific topological properties and an ensuing geomagnetic storm were predicted for September 30, assuming an average Sun-Earth transit time. A subsequent comparison with solar wind and geomagnetic data surrounding September 30 yielded a mixed level of success. Although a geomagnetic storm occurred on October 1, ironically, the strong southward magnetic field responsible for it was not encountered at the leading edge of the cloud, as predicted, but rather in the preceding sheath. In retrospect, the most likely sources of the southward field in the sheath were either a preceding CME or magnetic flux from high in the corona, not draped or turbulent flux from the ambient solar wind as is often supposed. With the aid of a flux rope model, we show that the elevation and polarity of the cloud axis and the chirality of the cloud were predicted correctly but that the trajectory of the spacecraft (and Earth) through what was deduced to be the leg of a flux rope loop precluded encounter with its leading southward field. The storm began with a sudden commencement near 0100 UT on October 1, corresponding to passage of a shock-like discontinuity, and the Dst storm index reached a minimum of -108 nT 14 hours later at 1500 UT. The leading edge of the cloud, however, coincident with the onset of counterstreaming electrons confirming its identification, was not encountered until 1700 UT. The disagreement between the predicted and actual arrival time reflects not only the lack of speed prediction capabilities but also the inability to predict whether encounter will be head-on with the apex of a flux rope loop or, as deduced in this case, passage through one of its legs. C1 Helio Res, Boulder, CO 80304 USA. Helio Res, La Crescenta, CA 91214 USA. Boston Univ, Ctr Space Phys, Boston, MA 02215 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Natl Ctr Atmospher Res, High Altitude Observ, Boulder, CO 80307 USA. RP McAllister, AH (reprint author), Helio Res, 1665 Lombardy Dr, Boulder, CO 80304 USA. EM ahm@dimensional.com; sara@helioresearch.org; crooker@bu.edu; rpl@leprpl1.gsfc.nasa.gov; u3rjf@leprjf.gsfc.nasa.gov NR 50 TC 23 Z9 23 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29185 EP 29194 DI 10.1029/2000JA000032 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500028 ER PT J AU Gopalswamy, N Lara, A Yashiro, S Kaiser, ML Howard, RA AF Gopalswamy, N Lara, A Yashiro, S Kaiser, ML Howard, RA TI Predicting the 1-AU arrival times of coronal mass ejections SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY SHOCKS; GEOMAGNETIC STORMS; MAGNETIC CLOUDS; TRANSIENTS; EARTH AB We describe an empirical model to predict the 1-AU arrival of coronal mass ejections (CMEs). This model is based on an effective interplanetary (IP) acceleration described by Gopalswamy et al. [2000b] that the CMEs are subject to, as they propagate from the Sun to 1 AU. We have improved this model (1) by minimizing the projection effects (using data from spacecraft in quadrature) in determining the initial speed of CMEs, and (2) by allowing for the cessation of the interplanetary acceleration before 1 AU. The resulting effective IP acceleration was higher in magnitude than what was obtained from CME measurements from spacecraft along the Sun-Earth line. We evaluated the predictive capability of the CME arrival model using recent two-point measurements from the Solar and Heliospheric Observatory (SOHO), Wind, and ACE spacecraft. We found that an acceleration cessation distance of 0.76 AU is in reasonable agreement with the observations. The new prediction model reduces the average prediction error from 15.4 to 10.7 hours. The model is in good agreement with the observations for high-speed CMEs. For slow CMEs the model as well as observations show a flat arrival time of similar to4.3 days. Use of quadrature observations minimized the projection effects naturally without the need to assume the width of the CMEs. However, there is no simple way of estimating the projection effects based on the surface location of the Earth-directed CMEs observed by a spacecraft (such as SOHO) located along the Sun-Earth line because it is impossible to measure the width of these CMEs. The standard assumption that the CME is a rigid cone may not be correct. In fact, the predicted arrival times have a better agreement with the observed arrival times when no projection correction is applied to the SOHO CME measurements. The results presented in this work suggest that CMEs expand and accelerate near the Sun (inside 0.7 AU) more than our model supposes; these aspects will have to be included in future models. C1 Catholic Univ Amer, Dept Phys, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. USN, Res Lab, Solar Phys Branch, Div Space Sci, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Autonomous Univ Mexico, Inst Geofis, Mexico City 04510, DF, Mexico. RP Gopalswamy, N (reprint author), Catholic Univ Amer, Dept Phys, Ctr Solar Phys & Space Weather, 200 Hannan Hall, Washington, DC 20064 USA. RI Gopalswamy, Nat/D-3659-2012; OI Lara, Alejandro/0000-0001-6336-5291 NR 27 TC 227 Z9 234 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29207 EP 29217 DI 10.1029/2001JA000177 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500030 ER PT J AU Gopalswamy, N Yashiro, S Kaiser, ML Howard, RA Bougeret, JL AF Gopalswamy, N Yashiro, S Kaiser, ML Howard, RA Bougeret, JL TI Characteristics of coronal mass ejections associated with long-wavelength type II radio bursts SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY SHOCKS; WIND SPACECRAFT; SOLAR CORONA; LASCO; ACCELERATION; TELESCOPE; EMISSIONS; MISSION; ORIGIN; PLASMA AB We investigated the characteristics of coronal mass ejections (CMES) associated with long-wavelength type II radio bursts in the near-Sun interplanetary medium. Type II radio bursts in the decameter-hectometric (DH) wavelengths indicate powerful MHD shocks leaving the inner solar corona and entering the interplanetary medium. Almost all of these bursts are associated with wider and faster than average CMEs. A large fraction of these radio-rich CMEs were found to decelerate in the coronagraph field of view, in contrast to the prevailing view that most CMEs display either constant acceleration or constant speed. We found a similar deceleration for the fast CMEs (speed > 900 km s(-1)) in general. We suggest that the coronal drag could be responsible for the deceleration, based on the result that the deceleration has a quadratic dependence on the CME speed. About 60% of the fast CMEs were not associated with DH type II bursts., suggesting that some additional condition needs to be satisfied to be radio-rich. The average width (66degrees) of the radio-poor, fast CMEs is much smaller than that (102degrees) of the radio-rich CMEs, suggesting that the CME width plays ail important role. The special characteristics of the radio-rich CMEs suggest that the detection of DH radio bursts may provide a useful tool in identifying the population of geoeffective CMEs. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Observ Paris, F-92195 Meudon, France. USN, Res Lab, Solar Phys Branch, Div Space Sci, Washington, DC 20375 USA. Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. RP Gopalswamy, N (reprint author), NASA, Goddard Space Flight Ctr, Bldg 26 Room G1,Mail Code 682-3, Greenbelt, MD 20771 USA. EM gopals@fugee.gsfc.nasa.gov; yashiro@cdaw.gsfc.nasa.gov; kaiser@lepmlk.gsfc.nasa.gov; howard@cronus.nrl.navy.mil; louis.bougeret@obspm.fr RI Gopalswamy, Nat/D-3659-2012 NR 28 TC 141 Z9 141 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29219 EP 29229 DI 10.1029/2001JA000234 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500031 ER PT J AU Lepri, ST Zurbuchen, TH Fisk, LA Richardson, IG Cane, HV Gloeckler, G AF Lepri, ST Zurbuchen, TH Fisk, LA Richardson, IG Cane, HV Gloeckler, G TI Iron charge distribution as an identifier of interplanetary coronal mass ejections SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; MAGNETIC CLOUDS; MINOR IONS; HELIUM; DECREASES; STATES; EVENTS; FLUX; ACE AB We present solar wind Fe charge state data measured on the Advanced Composition Explorer (ACE) from early 1998 to the middle of 2000. Average Fe charge states in the solar wind are typically around 9+ to 11+. However, deviations from these average charge states occur, including intervals with a large fraction of Fegreater than or equal to16+ which are consistently associated with interplanetary coronal mass ejections (ICMEs). By studying the Fe charge state distribution we are able to extract coronal electron temperatures often exceeding 2 X 10(6) kelvins. We also discuss the temporal trends of these events, indicating the more frequent appearance of periods with high Fe charge states as solar activity increases. C1 Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Lepri, ST (reprint author), Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. RI Lepri, Susan/I-8611-2012; OI Richardson, Ian/0000-0002-3855-3634 NR 35 TC 102 Z9 103 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29231 EP 29238 DI 10.1029/2001JA000014 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500032 ER PT J AU Liewer, PC Velli, M Goldstein, BE AF Liewer, PC Velli, M Goldstein, BE TI Alfven wave propagation and ion cyclotron interactions in the expanding solar wind: One-dimensional hybrid simulations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL HOLES; TURBULENCE-DRIVEN; RESONANT ACCELERATION; TRANSITION REGION; DISSIPATION RANGE; MAGNETIC-FIELD; MINOR IONS; HEAVY-IONS; CONSTRAINTS; DYNAMICS AB We carry out one-dimensional hybrid simulations of Alfven waves propagating along the magnetic field in the presence of a mean radial spherically expanding plasma outflow, representing fast solar wind stream. The equations for particle ions of multiple species and fluid electrons are solved using the Expanding Box Model, a locally Cartesian representation of motion in spherical coordinates, in a frame moving with the local average wind speed. The model gives a minimally consistent description of the effects associated with such motion on particle dynamics, e.g., the flux-conserving decrease of magnetic field intensity and consequent decrease of cyclotron frequency with increasing distance from the Sun. The cyclotron frequency decreases faster than Alfven wave frequency, allowing fluctuations below the cyclotron frequency at smaller distance from the Sun to come into cyclotron resonance at greater distances. The hybrid treatment yields a fully self-consistent description of the consequent cyclotron wave-particle interaction in a multi-ion plasma. We present results for cases of monochromatic circularly polarized Alfven waves propagating radially outward and for initially well developed Alfvenic spectra with and without alpha particles. When both alpha particles and protons axe present, the alpha particles, which come into resonance first as the wind expands, are observed to be preferentially heated and accelerated. For high beta (equal to ratio of ion pressure to magnetic field pressure) the amount of alpha particles acceleration and heating is limited by the available wave power. For low beta cases the amount of heating and acceleration is limited, not by the wave power, but by the depletion of the distribution function in the resonance region by pitch-angle scattering. The implication of these results for solar wind models is discussed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Florence, Dept Astron & Space Sci, I-50125 Florence, Italy. RP Liewer, PC (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 159-509, Pasadena, CA 91109 USA. NR 34 TC 63 Z9 63 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29261 EP 29281 DI 10.1029/2001JA000086 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500035 ER PT J AU Vasquez, BJ Farrugia, CJ Markovskii, SA Hollweg, JV Richardson, IG Ogilvie, KW Lepping, RP Lin, RP Larson, D AF Vasquez, BJ Farrugia, CJ Markovskii, SA Hollweg, JV Richardson, IG Ogilvie, KW Lepping, RP Lin, RP Larson, D TI Nature of fluctuations on directional discontinuities inside a solar ejection: Wind and IMP 8 observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Review ID EARTHS BOW SHOCK; IMBEDDED ROTATIONAL DISCONTINUITIES; CORONAL MASS EJECTIONS; COMPRESSIBLE MAGNETOHYDRODYNAMIC TURBULENCE; MAGNETICALLY STRUCTURED ATMOSPHERE; THERMAL ELECTRON DISTRIBUTIONS; KELVIN-HELMHOLTZ INSTABILITY; ION-CYCLOTRON WAVES; ALFVEN WAVES; TANGENTIAL DISCONTINUITIES AB A solar ejection passed the Wind spacecraft between December 23 and 26, 1996. On closer examination, we find a sequence of ejecta material, as identified by abnormally low proton temperatures, separated by plasmas with typical solar wind temperatures at 1 AU. Large and abrupt changes in field and plasma properties occurred near the separation boundaries of these regions. At the one boundary we examine here, a series of directional discontinuities was observed. We argue that Alfvenic fluctuations in the immediate vicinity of these discontinuities distort minimum variance normals, introducing uncertainty into the identification of the discontinuities as either rotational or tangential. Carrying out a series of tests on plasma and field data including minimum variance, velocity and magnetic field correlations, and jump conditions, we conclude that the discontinuities are tangential. Furthermore, we find waves superposed on these tangential discontinuities (TDs). The presence of discontinuities allows the existence of both surface waves and ducted body waves. Both probably form in the solar atmosphere where many transverse nonuniformities exist and where theoretically they have been expected. We add to prior speculation that waves on discontinuities may in fact be a common occurrence. In the solar wind, these waves can attain large amplitudes and low frequencies. We argue that such waves can generate dynamical changes at TDs through advection or forced reconnection. The dynamics might so extensively alter the internal structure that the discontinuity would no longer be identified as tangential. Such processes could help explain why the occurrence frequency of TDs observed throughout the solar wind falls off with increasing heliocentric distance. The presence of waves may also alter the nature of the interactions of TDs with the Earth's bow shock in so-called hot flow anomalies. C1 Univ New Hampshire, Inst Study Earth Oceans & Space, Ctr Space Sci, Durham, NH 03824 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Ctr Space Sci, Berkeley, CA 94720 USA. RP Vasquez, BJ (reprint author), Univ New Hampshire, Inst Study Earth Oceans & Space, Ctr Space Sci, Durham, NH 03824 USA. EM bernie.vasquez@unh.edu OI Richardson, Ian/0000-0002-3855-3634 NR 135 TC 14 Z9 15 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29283 EP 29298 DI 10.1029/2001JA000142 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500036 ER PT J AU Farrugia, CJ Erkaev, NV Vogl, DF Biernat, HK Oieroset, M Lin, RP Lepping, RP AF Farrugia, CJ Erkaev, NV Vogl, DF Biernat, HK Oieroset, M Lin, RP Lepping, RP TI Anisotropic magnetosheath: Comparison of theory with Wind observations near the stagnation streamline SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA DEPLETION LAYER; DAYSIDE MAGNETOPAUSE; SUBSOLAR MAGNETOSHEATH; TEMPERATURE ANISOTROPY; EARTHS MAGNETOSHEATH; PRESSURE ANISOTROPY; FLUID MODEL; WAVES; SPACECRAFT; CLOSURE AB We carry out a first comparison with spacecraft measurements of our recent three-dimensional, one-fluid magnetohydrodynamic (MHD) model for the anisotropic magnetosheath [Erkaev et al., 1999], using data acquired by the Wind spacecraft on an inbound magnetosheath pass on December 24, 1994. The spacecraft trajectory was very close to the stagnation streamline, being displaced by less than 1/2 hour from noon and passing at low southern magnetic latitudes (similar to4.5degrees). All quantities downstream of the bow shock are obtained by solving the Rankine-Hugoniot equations taking the pressure anisotropy into account. In this application of our model we close the MHD equations by a "bounded anisotropy" ansatz using for this purpose the inverse correlation between the proton temperature anisotropy, A(p) (equivalent to T-pperpendicular to/T-pparallel to - 1) and the proton plasma beta parallel to the magnetic field beta(pparallel to) observed on this pass when conditions are steady. In the model the total perpendicular pressure is prescribed and not obtained self-consistently. For all quantities studied we find very good agreement between the predicted and the observed profiles, indicating that the bounded anisotropy method of closing the magnetosheath equations, first suggested by Denton et al. [1994], is valid and reflects the physics of the magnetosheath well. We assess how sensitive our model results are to different parameters in the A(p) = alpha(0)beta(pparallel to)(-alpha1) (alpha(1) > 0) relation, taking for al the two limiting values (0.4, 0.5) resulting from the two-dimensional hybrid simulations of Gary et al. [1997], and varying alpha(0) in the range 0.6 - 0.8. Input solar wind conditions are as measured on this pass. In general, the model profiles depend more strongly on alpha(0) than on al. In particular, decreasing alpha(0) narrows the width of the plasma depletion layer (PDL) and widens the mirror stable region. For the lowest value of alpha(0) the mirror stable region extends sunward of the outer edge of the PDL. For the other two values of alpha(0) and regardless of the value of al, it is contained within the PDL. Finally, we also study phenomenological double-polytropic laws and find polytropic indices gamma(perpendicular to) approximate to 1 and gamma(parallel to) approximate to 1.5. These results agree well with those of Hau et al. [1993] inferred from Active Magnetospheric Particle Tracer Explorers/ Ion Release Module data on a crossing of the near-subsolar magnetosheath. C1 Univ New Hampshire, Inst Study Earth Oceans & Space, Ctr Space Sci, Durham, NH 03824 USA. Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria. Russian Acad Sci, Inst Computat Modelling, Krasnoyarsk 660036, Russia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Graz Univ, Inst Geophys Astrophys & Meteorol, Graz, Austria. Graz Univ, Inst Theoret Phys, A-8010 Graz, Austria. RP Farrugia, CJ (reprint author), Univ New Hampshire, Inst Study Earth Oceans & Space, Ctr Space Sci, Morse Hall,Room 414,39 Coll Rd, Durham, NH 03824 USA. RI Erkaev, Nikolai/M-1608-2013 OI Erkaev, Nikolai/0000-0001-8993-6400 NR 42 TC 19 Z9 19 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29373 EP 29385 DI 10.1029/2001JA000034 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500045 ER PT J AU Chen, Y Cloutier, PA Crider, DH Mazelle, C Reme, H AF Chen, Y Cloutier, PA Crider, DH Mazelle, C Reme, H TI On the role of charge exchange in the formation of the Martian magnetic pileup boundary SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND INTERACTION; ELECTRON-IMPACT IONIZATION; MARS GLOBAL SURVEYOR; FIELD OBSERVATIONS; 3-DIMENSIONAL MHD; UP BOUNDARY; VENUS; IONOSPHERE; DAYSIDE; MODEL AB In the magnetic pileup boundary (MPB) of Mars a steep increase in the magnitude of the magnetic field is observed in the data from the magnetometer on board Mars Global Surveyor, and the growth of the field is more precipitous than common solar wind-ionosphere models predict. Analysis of both Venus and Mars magnetic field data has strongly implied that plasma pressure is exchanged for magnetic pressure in the magnetic pileup field. To explain this, effects of the Martian exosphere must be included. Then charge exchange between the shock-compressed solar wind protons, which dominate the thermal pressure, and neutral exospheric atoms (mainly H and 0) should play a crucial role in the formation of the MPB, as is also inherently required by the conservation of momentum flux. To test this idea, a model of the solar wind interaction with the Martian upper atmosphere, with charge exchange included, is constructed to reproduce the observed magnetic field of the MPB of Mars. The simulation results show that charge exchange is able to account for the sudden buildup of the magnetic field in the Martian MPB, with the implication that the same mechanism produces the magnetic field increase at Venus and comets. C1 Rice Univ, Dept Space Phys & Astron, Houston, TX 77005 USA. NASA, Goddard Space Flight Ctr, Natl Res Council, Greenbelt, MD 20771 USA. CNRS, Ctr Etud Spatiale Rayonnements, F-31028 Toulouse, France. RP Chen, Y (reprint author), Rice Univ, Dept Space Phys & Astron, 6100 Main St,MS 108, Houston, TX 77005 USA. RI Hurley, Dana/F-4488-2015 OI Hurley, Dana/0000-0003-1052-1494 NR 34 TC 8 Z9 8 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29387 EP 29399 DI 10.1029/2000JA000411 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500046 ER PT J AU Wibberenz, G Cane, HV AF Wibberenz, G Cane, HV TI Comment on "Simple analytical solutions for propagating diffusive barriers and application to the 1974 minicycle" by G. Wibberenz and H.V. Cane - Reply SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Editorial Material ID COSMIC-RAY MODULATION; MAGNETIC-FIELD C1 Univ Kiel, Inst Expt & Angew Phys, D-24118 Kiel, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Tasmania, Sch Math & Phys, Hobart, Tas, Australia. RP Wibberenz, G (reprint author), Univ Kiel, Inst Expt & Angew Phys, Olshaussenstr 40, D-24118 Kiel, Germany. NR 10 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29413 EP 29415 DI 10.1029/2001JA900105 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500049 ER PT J AU Zeng, W Horwitz, JL Stevenson, BA Wu, XY Su, YJ Craven, PD Rich, FJ Moore, TE Tu, JN AF Zeng, W Horwitz, JL Stevenson, BA Wu, XY Su, YJ Craven, PD Rich, FJ Moore, TE Tu, JN TI Near-simultaneous Polar and DMSP measurements of topside ionospheric field-aligned flows at high latitudes SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOFT-ELECTRON-PRECIPITATION; F-REGION; WIND; MODEL; IONS; O+; MAGNETOSPHERE; OUTFLOW; CONICS; CAP AB Near-simultaneous observations of topside O+ parallel flows are presented for four periods of measurement by the Polar and DMSP satellites during April 1996. The Polar measurements were from southern perigee measurements near 5000 km altitude, while the DMSP measurements were from 840 km altitude. In general, the velocities were upward at expected cleft and auroral latitudes, typically about 2-10 km s(-1) at 5000 km altitude, and 0-2 km s(-1) at 840 km altitude. At the highest, polar cap latitudes, downward velocities were more frequent at both altitudes, but especially at the lower 840 km altitude. The downward velocities were typically a few hundred meters per second at 840 km altitude, and 0-1 km s(-1) at 5000 km altitude. In some instances, downward velocities were observed at 840 km altitude while upward O+ flows were observed at 5000 km altitude, possibly on the same flux tube. The O+ densities were characteristically 1-10 O+ cm(-3) at 5000 km altitude and 10(3) -10(4) O+ cm(-3) at 840 km altitude, while the O+ fluxes were characteristically 10(5) - 10(7) O+ cm(-1) s(-1) at 5000 km altitude and characteristically 10(7) - 10(9) O+ cm(-2) s(-1) at 840 km altitude. We have also examined the dual-altitude parameter measurements for a polar cap field line, the Polar and DMSP measurements approximately 30 min apart, and compared them with results from a transport simulation. The simulated high-altitude velocity altitude profiles for the period during and after the initiation of the auroral processes generally bracketed the observations, but the observed downward velocities (500 - 600 m s(-1)) at 840 km altitude were much larger in magnitude than those in the transport simulation, and the simulated densities were several times higher than those observed at both altitudes. C1 Univ Alabama, Ctr Space Plasma & Aeronom Res, Huntsville, AL 35899 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35805 USA. USAF, Res Lab, Hanscom AFB, MA 01731 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Zeng, W (reprint author), Univ Alabama, Ctr Space Plasma & Aeronom Res, Huntsville, AL 35899 USA. RI Moore, Thomas/D-4675-2012; OI Moore, Thomas/0000-0002-3150-1137; Stevenson, Benjamin/0000-0001-9918-1240 NR 28 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29601 EP 29610 DI 10.1029/2000JA000332 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500064 ER PT J AU Stenuit, H Sauvaud, JA Delcourt, DC Mukai, T Kokubun, S Fujimoto, M Buzulukova, NY Kovrazhkin, RA Lin, RP Lepping, RP AF Stenuit, H Sauvaud, JA Delcourt, DC Mukai, T Kokubun, S Fujimoto, M Buzulukova, NY Kovrazhkin, RA Lin, RP Lepping, RP TI A study of ion injections at the dawn and dusk polar edges of the auroral oval SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID UPSTREAM PRESSURE VARIATIONS; LATITUDE BOUNDARY-LAYER; MAGNETIC-FIELD; PLASMA SHEET; MAGNETOSPHERIC RESPONSE; PARTICLE-PRECIPITATION; EXPERIMENT ONBOARD; PC-5 PULSATIONS; MAGNETOPAUSE; MAGNETOSHEATH AB In the auroral dawn and dusk magnetosphere at altitudes of similar to2-3 R-E, three distinct zones of ion and electron precipitation are commonly detected onboard Interball 2, near the polar edge of the auroral oval. From high to low latitudes the satellite encounters (1) magnetosheath/low-latitude boundary layer (LLBL) like plasma (Zone 1), (2) a mixing region with plasma characteristics between LLBL and plasma sheet (Zone 2), and (3) the auroral plasma sheet precipitation (Zone 3). Further equatorward, the satellite crosses the inner plasma sheet characterized by "ion gaps" in the morning sector. Inside Zones I and 2 impulsive ion injections are often detected. They consist of overlapping energy dispersed structures from about 10 keV down to several hundreds of eV with temperature close to that of the magnetosheath. Using trajectory computations backward in time, these dispersions are shown to be cause by time-of-flight effect from a distant source located close to the equatorial magnetopause. Whereas Zone 1 is located mainly poleward of region 1 (downward field-aligned currents at dawn and upward field-aligned currents at dusk), Zone 2 generally coincides with region 1. It is mainly located on closed field lines, as evidenced from the local detection of bouncing ion clusters. Finally, Zone 3 corresponds with region 2 of upward field-aligned currents. A statistical study of Zone I which is present in about 12% of the satellite passes at dawn and dusk reveals that its probability of occurrence seems to be controlled by the interplanetary magnetic field (IMF). That is, it is formed when the IMF has a northward component and tends to be radially directed. Moreover, it is more frequently encountered during periods of enhanced solar wind pressure. Detailed case studies uncover a remarkable correlation between the onsets of individual injections inside Zone I and those of pressure pulses in the magnetosheath. Both have a characteristic period of similar to200-250 s, similar to that of Pc5 events associated with these injections and detected on board Interball 2. Altogether, these observations indicate that injections and related Alfven waves are driven by magnetosheath pressure pulses associated with a quasi-parallel bow shock. The plasma penetration mechanism remains to be understood. C1 Ctr Etud Spatiale Rayonnements, CNRS, F-31028 Toulouse 4, France. Ctr Etud Environm Terr & Planetaires, CNRS, F-94107 St Maur des Fosses, France. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. Nagoya Univ, STE Lab, Toyokawa, Aichi 442, Japan. Tokyo Inst Technol, Dept Earth & Planetary Sci, Meguro Ku, Tokyo 152, Japan. Inst Space Res, IKI, Moscow 117997, Russia. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Stenuit, H (reprint author), Ctr Etud Spatiale Rayonnements, CNRS, 9 Ave Colonel Roche, F-31028 Toulouse 4, France. NR 46 TC 12 Z9 12 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29619 EP 29631 DI 10.1029/2001JA900060 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500066 ER PT J AU Blake, JB Inan, US Walt, M Bell, TF Bortnik, J Chenette, DL Christian, HJ AF Blake, JB Inan, US Walt, M Bell, TF Bortnik, J Chenette, DL Christian, HJ TI Lightning-induced energetic electron flux enhancements in the drift loss cone SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RADIATION BELT ELECTRONS; SUBIONOSPHERIC VLF SIGNATURES; EARTHS INNER MAGNETOSPHERE; SCATTERING LOSS; PRECIPITATION; WHISTLERS; EVENTS AB With its relatively low altitude (520 X 670 km) orbit, SAMPEX is mostly below the stable trapping region where charged particles repeatedly drift around the Earth, especially at midlatitudes. Recent analyses of SAMPEX data have revealed a surprisingly common set of observations of enhanced energetic (>150 keV) electron fluxes at L < 3, during times when SAMPEX was located such that any electrons that it observed were in the drift loss cone (and were thus destined to be precipitated upon reaching the longitude of the South Atlantic Magnetic Anomaly in the course of their eastward drift). The data were acquired with the Heavy Ion Large Telescope on board SAMPEX, which provides high time resolution measurements (30 ms sample rate) of electrons above energy thresholds of 150 keV and 1 MeV. Preliminary examination of 1995 SAMPEX data (when the >150 keV detector was available) revealed hundreds of cases of newly enhanced drift loss cone fluxes in localized L shell regions often associated with individual thunderstorms. In one case, SAMPEX data from three consecutive days (95/196, 95/197, and 95/198) were analyzed as the satellite proceeded northbound over the same ground track from west of New Zealand and Hawaii toward Alaska, with the underlying lightning activity documented by the Optical Transient Detector on board the OrbView-1 satellite (750 km, 70degrees inclination circular orbit). Enhanced fluxes observed on SAMPEX during day 95/197 were directly associated with an oceanic storm just to the west of the SAMPEX ground track, which was well placed to generate the observed drift loss cone flux enhancements. The drift loss cone electron flux enhancements were also observed 20 min later as SAMPEX crossed the same L shells in the north and in subsequent orbits, indicating that lightning-induced precipitation of electrons into the drift loss cone persisted at least for a few hours. Data from UARS satellite, passing through the same region within the same hour, also confirmed the presence of L-dependent structure and further allowed the determination of the electron energy spectra, which exhibited a general shape and range strikingly similar to previously documented spectral characteristics of lightning-induced electron precipitation (LEP) events in the bounce loss cone [Voss et al., 1998]. This similarity lends support to the argument that the observed drift loss cone features are produced by the LEP process. In summary, SAMPEX data indicate that globally distributed thunderstorms may continually precipitate energetic electrons from the radiation belts, producing transient enhancements in the drift loss cone that are detected within the few hour periods as they drift around the Earth and precipitate in the South Atlantic Magnetic Anomaly. C1 Aerosp Corp, Dept Space Sci, Los Angeles, CA 90009 USA. Stanford Univ, Dept Elect Engn, STARLab, Stanford, CA 94305 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Blake, JB (reprint author), Aerosp Corp, Dept Space Sci, Box 92957,M2-259, Los Angeles, CA 90009 USA. NR 30 TC 25 Z9 26 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29733 EP 29744 DI 10.1029/2001JA000067 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500074 ER PT J AU Hesse, M Kuznetsova, M Birn, J AF Hesse, M Kuznetsova, M Birn, J TI Particle-in-cell simulations of three-dimensional collisionless magnetic reconnection SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID THIN CURRENT SHEETS; MAGNETOSPHERIC SUBSTORMS; ELECTRON DISSIPATION; EARTHS MAGNETOPAUSE; KINK INSTABILITY; DYNAMICS; MAGNETOTAIL; MECHANISM; REGION; MODEL AB Three-dimensional simulations of collisionless magnetic reconnection in a current sheet configuration are presented. The study consists of two parts: a simulation of a current sheet with an initial perturbation and another model run without it. Particular emphasis is on the questions (1) whether magnetic reconnection remains two-dimensional if it initiates so, and (2) whether reconnection favors a patchy, localized mode over long, extended reconnection regions. Our study suggests that results from 2.5-dimensional models of reconnection are not substantially altered by including variations in the third dimension. In fact, an initially random patchy reconnection structure appear to self-organize into a more coherent quasi-two-dimensional structure. As in 2.5-dimensional reconnection studies, the dominant contribution to the dissipation stems from off-diagonal terms of the electron pressure tensor in our simulations. The dominant term is related to oscillatory electron motions between the regions of newly reconnected magnetic field. C1 NASA, Goddard Space Flight Ctr, Electrodynam Branch, Greenbelt, MD 20771 USA. RP Hesse, M (reprint author), Los Alamos Natl Lab, Space Sci Grp, POB 1663, Los Alamos, NM 87544 USA. RI Hesse, Michael/D-2031-2012; Kuznetsova, Maria/F-6840-2012 NR 42 TC 36 Z9 38 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29831 EP 29841 DI 10.1029/2001JA000075 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500080 ER PT J AU Davis, AJ Mewaldt, RA Cohen, CMS Cummings, AC George, JS Leske, RA Stone, EC Wiedenbeck, ME Yanasak, NE Christian, ER von Rosenvinge, TT Binns, WR Hink, PL AF Davis, AJ Mewaldt, RA Cohen, CMS Cummings, AC George, JS Leske, RA Stone, EC Wiedenbeck, ME Yanasak, NE Christian, ER von Rosenvinge, TT Binns, WR Hink, PL TI Solar minimum spectra of galactic cosmic rays and their implications for models of the near-earth radiation environment SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ADVANCED-COMPOSITION-EXPLORER; ISOTOPE SPECTROMETER; MODULATION AB The radiation dose from galactic cosmic rays during a manned mission to Mars is expected to be comparable to the allowable limit for space shuttle astronauts. Most of this dose would be due to galactic cosmic rays with energies < 1 GeV nucleon(-1), with important contributions from heavy nuclei in spite of their low abundance relative to H and He. Using instruments on NASA's Advanced Composition Explorer (ACE) spacecraft, we have made the most statistically precise measurements to date of the solar minimum energy spectra of cosmic ray nuclei with charge Z = 4-28 in the energy range similar to40-500 MeV nucleon(-1). We compare these measurements obtained during the 1997-1998 solar minimum period with measurements from previous solar minima and with models of the near-Earth radiation environment currently used to perform shielding and dose calculations. We find that the cosmic ray heavy-element spectra measured by ACE are as much as 20% higher than previously published solar minimum measurements. We also find significant differences between the ACE measurements and the predictions of available models of the near-Earth radiation environment, suggesting that these models need revision. We describe a cosmic ray interstellar propagation and solar modulation model that provides an improved fit to the ACE measurements compared to radiation environment models currently in use. C1 CALTECH, Dept Phys, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Washington Univ, Dept Phys, St Louis, MO 63130 USA. RP Davis, AJ (reprint author), CALTECH, Dept Phys, Mail Code 220-47, Pasadena, CA 91125 USA. RI Christian, Eric/D-4974-2012 OI Christian, Eric/0000-0003-2134-3937 NR 25 TC 16 Z9 16 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29979 EP 29987 DI 10.1029/2000JA000325 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500097 ER PT J AU Reiner, MJ Kaiser, ML Bougeret, JL AF Reiner, MJ Kaiser, ML Bougeret, JL TI Radio signatures of the origin and propagation of coronal mass ejections through the solar corona and interplanetary medium SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID WIND SPACECRAFT DATA; SHOCKS; EMISSIONS; BURSTS; MHZ; LOCATION; EVENTS; DRIVEN; 1-AU AB During a 16-day period from February 5 to 20, 2000, a series of decametric-to-kilometric wavelength type II and type III radio events was observed by the WAVES radio experiment on board the Wind spacecraft. These radio events were related to observed coronal mass ejections (CMEs) and their associated flares. Each of the solar eruptive events was initiated by an intense, complex type III radio burst, which occurred within minutes of the liftoff on the CME. Some of the CMEs produced decametric-hectometric (D-H) type II radio emissions, which, when their frequency drift rates were sufficiently well defined, were used to provide a speed estimate. The complex type III and D-H type II radio emissions gave an indication of the presence of a CME well before the CME was first observed in the coronagraph images. This series of CMEs also generated interplanetary (kilometric) type II radio emissions that tracked the CME-associated shock through the interplanetary medium and established the terrestrial connection. Thus the various radio emissions associated with these solar eruptive events provided a global view of each entire Sun-Earth connection event, from the initiation and liftoff of the CME at the Sun, to the propagation of the CME-associated shock through the solar corona and interplanetary medium, to its arrival at 1 AU. Finally, we show that simultaneous Wind/Ulysses observations of the interplanetary type II radio emissions on February 9 - 10 provide important information on the nature of the type II emission, on the type II source locations, and on the radiation characteristics of the type II emissions. For example, these simultaneous observations clearly indicate that the sporadic nature of the type II radiation was intrinsic to the radio source region. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Observ Paris, F-92195 Meudon, France. RP Reiner, MJ (reprint author), Raytheon ITSS, Lanham, MD USA. NR 43 TC 29 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 29989 EP 30000 DI 10.1029/2000JA002228 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500098 ER PT J AU Leske, RA Mewaldt, RA Stone, EC von Rosenvinge, TT AF Leske, RA Mewaldt, RA Stone, EC von Rosenvinge, TT TI Observations of geomagnetic cutoff variations during solar energetic particle events and implications for the radiation environment at the Space Station SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID POLAR-CAP; TELESCOPE; BOUNDARY AB Data from the polar-orbiting Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite have been used to measure the location of the geomagnetic cutoff for low-energy protons and alpha particles during several large solar energetic particle events from mid-1992 to late 1998. When fluxes are sufficiently high, the cutoff latitude can be measured up to four times per orbit, allowing the variability of the cutoff to be observed on relatively short timescales. We find significant changes in the cutoff location, often by more than 5degrees in less than 1 day, and these changes are well correlated with geomagnetic activity as measured by either Dst or Kp. Spacecraft in intermediate-inclination orbits such as the International Space Station (ISS) graze the geomagnetic polar cap at certain longitudes each day. Calculations show that a 5degrees suppression in the average geomagnetic cutoff increases by more than a factor of 2.5 the time that the ISS spends in the polar cap exposed to energetic particles. Since the Station is only vulnerable at certain longitudes, however, real-time monitoring of the cutoff location from a polar-orbiting spacecraft could be used to provide advance notice of the polar cap location and conditions, sometimes hours before the Space Station itself reaches high magnetic latitudes. C1 CALTECH, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Leske, RA (reprint author), CALTECH, Mail Code 220-47, Greenbelt, MD 20771 USA. NR 19 TC 56 Z9 56 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30011 EP 30022 DI 10.1029/2000JA000212 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500100 ER PT J AU Pesnell, WD Goldberg, RA Chenette, DL Gaines, EE Schulz, M AF Pesnell, WD Goldberg, RA Chenette, DL Gaines, EE Schulz, M TI Growth and decay of relativistic electrons during a magnetic storm as seen in low-Earth orbit SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MIDDLE ATMOSPHERE; ENERGETIC PARTICLES; UARS; DEPOSITION; EVENT; OZONE AB Highly relativistic electron events (HREs) are periods of intense, long-lived, energetic electron fluxes in the outer radiation zone. We are using measurements from the High Energy Particle Spectrometer (HEPS) on the Upper Atmosphere Research Satellite (UARS) to develop a database of the pitch-angle-resolved and energy-resolved electron fluxes with energies between 30 keV and 5 MeV. The data acquired by HEPS have overlapped with the declining phase of solar cycle 22, making these data very important since HREs are thought to peak in frequency and intensity during this phase of the solar cycle. We find a consistent scenario of electrons being injected into radiation belts by a magnetic storm (deduced from Dst) and being slowly accelerated to ever higher energies over days to weeks. The energy dependence of the flux is an essential part of the analysis. Above 700keV the most energetic electrons are the last to appear and the slowest to fade following an injection event. C1 Nomad Res Inc, Arnold, MD 21012 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Lockheed Martin Adv Technol Div, Space Phys Dept, Palo Alto, CA USA. RP Pesnell, WD (reprint author), Nomad Res Inc, 795 Scarborough Court, Arnold, MD 21012 USA. RI Goldberg, Richard /E-1881-2012; Pesnell, William/D-1062-2012 OI Pesnell, William/0000-0002-8306-2500 NR 21 TC 1 Z9 1 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30039 EP 30046 DI 10.1029/2000JA000221 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500102 ER PT J AU Burton, ME Buratti, B Matson, DL Lebreton, JP AF Burton, ME Buratti, B Matson, DL Lebreton, JP TI The Cassini/Huygens Venus and Earth flybys: An overview of operations and results SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article AB The Cassini/Huygens spacecraft flew by Venus on June 24, 1999, and the Earth on August 18, 1999. These two events provided the Cassini Project with its first opportunities to design coordinated scientific observations at planetary encounters. In addition to exercising capabilities of the science instruments as well as the spacecraft and performing instrument calibrations, new scientific data were obtained. We present an overview of these two planetary flybys, describe the processes used to plan and design the observations, and highlight the major scientific results presented in the papers that follow. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. European Space Technol Ctr, NL-2200 AG Noordwijk, Netherlands. RP Burton, ME (reprint author), CALTECH, Jet Prop Lab, MC 169-506,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 16 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30099 EP 30107 DI 10.1029/2001JA900088 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500107 ER PT J AU Southwood, DJ Dougherty, MK Balogh, A Cowley, SWH Smith, EJ Tsurutani, BT Russell, CT Siscoe, GL Erdos, G Glassmeier, KH Gleim, F Neubauer, FM AF Southwood, DJ Dougherty, MK Balogh, A Cowley, SWH Smith, EJ Tsurutani, BT Russell, CT Siscoe, GL Erdos, G Glassmeier, KH Gleim, F Neubauer, FM TI Magnetometer measurements from the Cassini Earth swing-by SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FLUX-TRANSFER EVENTS; 1-2 MAGNETIC PULSATIONS; LOW-FREQUENCY WAVES; MIRROR MODE WAVES; ROTATIONAL DISCONTINUITIES; EQUATORIAL MAGNETOSPHERE; INNER MAGNETOSHEATH; BOUNDARY-LAYER; SOLAR-WIND; MAGNETOPAUSE AB Magnetometer data recorded by the Cassini spacecraft during the spacecraft's Earth swing-by maneuver in August 1999 are discussed. The primary purpose of this paper is to show the instrument's performance in detection of magnetic phenomena in a planetary environment. Companion papers put the data in a broader geophysical context. The low noise and high time resolution of the instrument coupled with the unusual orbit did produce new information about old phenomena (e.g., a whistler-like signal inside the near-subsolar magnetopause, lower hybrid noise in the current sheets around a magnetosheath field null, and sharp changes in the ion cyclotron wave spectrum between the boundary layer and magnetosphere proper). The detection of irregular isolated 1-2 s duration small-amplitude field strength dips in the vicinity of the nightside plasma trough appear to constitute a new discovery, tentatively identified as being evidence of plasmasphere interchange instability during a lull in background convection. The absolute scalar element of the instrument worked to plan, operating within 4 RE of Earth in parallel with the fluxgate sensors. In all respects, instrument performance bodes well for the Saturn orbital phase of the mission. C1 Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2BZ, England. Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. Boston Univ, Ctr Space Phys, Boston, MA 02215 USA. KFKI Res Inst Particle & Nucl Phys, H-1525 Budapest, Hungary. Tech Univ Carolo Wilhelmina Braunschweig, Inst Datenverabeitungsanlagen, D-38106 Braunschweig, Germany. Univ Cologne, Inst Geophys & Meterol, D-50923 Cologne, Germany. RP Southwood, DJ (reprint author), European Space Agcy Headquarters, F-75738 Paris 15, France. NR 69 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30109 EP 30128 DI 10.1029/2001JA900110 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500108 ER PT J AU Smith, EJ Dougherty, MK Russell, CT Southwood, DJ AF Smith, EJ Dougherty, MK Russell, CT Southwood, DJ TI Scalar helium magnetometer observations at Cassini Earth swing-by SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD; MODEL AB When the Cassini spacecraft passed by Earth en route to the outer solar system, the magnetic field magnitude was measured with extremely high accuracy by the onboard helium magnetometer operating in the scalar mode. Magnitude measurements of the near-equatorial field were obtained inbound from 4 to 1.17 R-E at local times from postnoon to dusk and outbound to 4 R-E between dusk and midnight. The observed field consisted of both the internally generated field of Earth and the field of external magnetospheric currents which were enhanced because of an ongoing magnetic storm. The contribution of the internal field was removed using a current version of the International Geomagnetic Reference Field (IGRF). An excellent characterization of the disturbance field was then obtained as a function of radial distance and local time. The observations were compared with available models of the disturbance field. Reasonable agreement was obtained, but discrepancies were found that were large enough to require changes in some of the model parameters. After removing the disturbance field, accuracy of measurement of high-degree spherical harmonic moments of a planetary field, an important objective at Saturn, was investigated. The contribution of the sum of high-degree moments to the Earth's field magnitude was obtained from the IGRF. The corresponding contribution to the measured field magnitude was derived using a theorem developed for that purpose. A close correspondence between the Cassini measurements and the IGRF was then found. The physics underlying the scalar measurements and the implementation of this mode in the Cassini magnetometer, the first time on a planetary mission, are described. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2BZ, England. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. RP Smith, EJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30129 EP 30139 DI 10.1029/2001JA900115 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500109 ER PT J AU Tsurutani, BT Smith, EJ Burton, ME Arballo, JK Galvan, C Zhou, XY Southwood, DJ Dougherty, MK Glassmeier, KH Neubauer, FM Chao, JK AF Tsurutani, BT Smith, EJ Burton, ME Arballo, JK Galvan, C Zhou, XY Southwood, DJ Dougherty, MK Glassmeier, KH Neubauer, FM Chao, JK TI Oblique "1-Hz" whistler mode waves in an electron foreshock: The Cassini near-Earth encounter SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID BOW SHOCK; UPSTREAM WAVES; HYDROMAGNETIC-WAVES; NOVEMBER 1; IONS; CONSEQUENCES; SIMULATIONS; EXCITATION AB The Cassini spacecraft flew toward the Earth in a trajectory almost along the Sun-Earth line, giving a unique perspective of low-frequency plasma waves in the Earth's foreshock. At the time of the fly-through, the angle between the magnetic field and Sun-Earth direction was similar to70degrees. For this orientation, only the most energetic (greater than or equal to12 keV) ions could reach the upstream region, thus Cassini passed through an almost "pure" electron foreshock. We demonstrate the presence of nonlinear foreshock "1-Hz" whistler-mode waves and their properties. Power spectra demonstrate that the waves span a frequency range from similar to0.3 to similar to10 Hz with a center frequency of similar to2 Hz. Close to the bow shock the waves had peak-to-peak transverse amplitudes as large as similar to14 nT in a 35-nT ambient field. The waves were compressive with a maximum value of Delta\B\/B-0 approximate to 0.25. The waves were propagating primarily along B-0. Of the waves, 82% were right-hand-polarized, 9% were linearly polarized, and 9% were left-hand-polarized (in the spacecraft frame). The wave amplitudes were largest near the bow shock and decreased with increasing distance in the upstream direction. Further from the shock the waves are determined to be propagating obliquely to B-0 (theta(kB) greater than or equal to 20degrees). There is an equal mix of right-hand, left-hand, and linearly polarized (in the spacecraft frame) waves. Left-hand-polarized waves propagating parallel to B-0 were not detected. Wave power changed dramatically as the interplanetary magnetic field rotated slightly. Arguments are presented for why low-energy (tens of eV) electrons are responsible for wave generation, rather than cyclotron resonant energetic (> 13 keV) electrons. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ London Imperial Coll Sci Technol & Med, Blackett Lab, Space & Atmospher Phys Grp, London SW7 2BZ, England. Tech Univ Braunschweig, Inst Geophys, D-38106 Braunschweig, Germany. Univ Cologne, Inst Geophys & Meteorol, D-50923 Cologne, Germany. Natl Cent Univ, Inst Space Sci, Chungli 320, Taiwan. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM Bruce.Tsurutani@jpl.nasa.gov NR 41 TC 3 Z9 3 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30223 EP 30238 DI 10.1029/2001JA900108 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500114 ER PT J AU Kurth, WS Hospodarsky, GB Gurnett, DA Kaiser, ML Wahlund, JE Roux, A Canu, P Zarka, P Tokarev, Y AF Kurth, WS Hospodarsky, GB Gurnett, DA Kaiser, ML Wahlund, JE Roux, A Canu, P Zarka, P Tokarev, Y TI An overview of observations by the Cassini radio and plasma wave investigation at Earth SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID AURORAL KILOMETRIC RADIATION; MAGNETOTAIL; SPACECRAFT; EMISSIONS; FLUX AB On August 18, 1999, the Cassini spacecraft flew by Earth at an altitude of 1186 km on its way to Saturn. Although the flyby was performed exclusively to provide the spacecraft with sufficient velocity to get to Saturn, the radio and plasma wave science (RPWS) instrument, along with several others, was operated to gain valuable calibration data and to validate the operation of a number of capabilities. In addition, an opportunity to study the terrestrial radio and plasma wave environment with a highly capable instrument on a swift fly-through of the magnetosphere was afforded by the encounter. This paper provides an overview of the RPWS observations at Earth, including the identification of a number of magnetospheric plasma wave modes, an accurate measurement of the plasma density over a significant portion of the trajectory using the natural wave spectrum in addition to a relaxation sounder and Langmuir probe, the detection of natural and human-produced radio emissions, and the validation of the capability to measure the wave normal angle and Poynting flux of whistler-mode chorus emissions. The results include the observation of a double-banded structure at closest approach including a band of Cerenkov emission bounded by electron plasma and upper hybrid frequencies and an electron cyclotron harmonic band just above the second harmonic of the electron cyclotron frequency. In the near-Earth plasma sheet, evidence for electron phase space holes is observed, similar to those first reported by Geotail in the magnetotail. The wave normal analysis confirms the Polar result that chorus is generated very close to the magnetic equator and propagates to higher latitudes. The integrated power flux of auroral kilometric radiation is also used to identify a series of substorms observed during the outbound passage through the magnetotail. C1 Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Swedish Inst Space Phys, Uppsala Div, S-75591 Uppsala, Sweden. Univ Versailles St Quentin Yvelines, Ctr Etude Environm & Planetaires, F-92131 Velizy Villacoublay, France. Observ Paris, F-92195 Meudon, France. Radiophys Res Inst, Nizhnii Novgorod 603950, Russia. RP Kurth, WS (reprint author), Univ Iowa, Dept Phys & Astron, 203 Van Allen Hall, Iowa City, IA 52242 USA. OI Hospodarsky, George/0000-0001-9200-9878; Kurth, William/0000-0002-5471-6202 NR 28 TC 13 Z9 13 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30239 EP 30252 DI 10.1029/2001JA900033 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500115 ER PT J AU Lorenz, RD Elachi, C West, RD Johnson, WTK Janssen, MA Moghaddam, M Hamilton, GA Liepack, O Bunker, A Roth, LE Wall, SD Dente, L Casarano, D Posa, F AF Lorenz, RD Elachi, C West, RD Johnson, WTK Janssen, MA Moghaddam, M Hamilton, GA Liepack, O Bunker, A Roth, LE Wall, SD Dente, L Casarano, D Posa, F TI Cassini Radio Detection and Ranging (RADAR): Earth and Venus observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LAND SCATTEROMETER DATA AB The Cassini Radio Detection and Ranging (RADAR) was operated in scatterometric and radiometric modes during the Venus 1 and Earth swingbys to verify its functionality. At Venus, only the thermal emission from the thick absorbing atmosphere was detected. At Earth both the radar echo and the microwave emission from the surface were detected and reveal ocean surface disturbances, the rough, high, and cold Andes mountains, and surface features including a small reservoir in Brazil. Instrument performance appears to be excellent. C1 Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Ist Nazl Fis Mat, Dipartimento Interateneo Fis, I-70126 Bari, Italy. RP Lorenz, RD (reprint author), Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RI Dente, Laura/D-4646-2009; Lorenz, Ralph/B-8759-2016 OI Lorenz, Ralph/0000-0001-8528-4644 NR 20 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30271 EP 30279 DI 10.1029/2001JA900035 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500117 ER PT J AU Tsai, HF Liu, JY Tsai, WH Liu, CH Tseng, CL Wu, CC AF Tsai, HF Liu, JY Tsai, WH Liu, CH Tseng, CL Wu, CC TI Seasonal variations of the ionospheric total electron content in Asian equatorial anomaly regions SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article AB The ionospheric total electron contents (TEC) in both northern and southern equatorial anomaly regions are examined by using the Global Positioning System (GPS) in Asian area. The TEC contour charts obtained at YMSM (25.2degreesN, 121.6degreesE; 14.0degreesN geomagnetic) and DGAR (7.3degreesS, 72.4degreesE; 16.2degreesS geomagnetic) stations in 1997, solar minimum, are investigated. It is found that the ionospheric crests manifest remarkable seasonal variations. The TEC values on both northern and southern equatorial anomaly crests yield their maximum values during the vernal and autumnal months, but the winter anomaly does not appear in the southern region. Results show that both crests are fully developed around midday in winter, postnoon in equinoxes and late afternoon in summer, and the two crests move significantly equatorward in winter but slightly poleward in summer and autumn. These phenomena can be fully explained by a combined theory of the transequatorial netural wind, the subsolar point, and the auroral equatorward wind. C1 Natl Cent Univ, Inst Space Sci, Jungli 32001, Taoyuan, Taiwan. Natl Cheng Kung Univ, Satellite Geoinformat Res Ctr, Tainan 701, Taiwan. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Natl Cent Univ, Ctr Space & Remote Sensing Res, Jungli, Taoyuan, Taiwan. RP Tsai, HF (reprint author), Natl Cent Univ, Inst Space Sci, Jungli 32001, Taoyuan, Taiwan. RI Liu, Jann-Yenq/Q-1668-2015 NR 15 TC 48 Z9 51 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30363 EP 30369 DI 10.1029/2001JA001107 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500127 ER PT J AU Kilifarska, NA Ouzounov, DP AF Kilifarska, NA Ouzounov, DP TI Theoretical modeling of foF(2) and h(m)F(2) ionospheric parameters during a strong magnetic disturbance SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID THERMOSPHERIC COMPOSITION PERTURBATIONS; ELECTRON-CONCENTRATION; GEOMAGNETIC STORMS; GLOBAL-MODEL; F-LAYER; SATELLITE; WINDS; ATMOSPHERE; HEIGHT AB The theoretical data assimilative model of the ionosphere (TDAMI) was created to answer the most challenging problem in ionospheric physics: modeling the ionospheric disturbances (in particular, parameters related to the peak of the F layer: f(o)F(2) and h(m)F(2)) during geomagnetic storms. It is an analytical model that calculates maximum electron density (N-m) distribution and the height of this maximum (h(m)) as a function of time, latitude, longitude, season and solar activity. Tested as a "climatological", i.e., monthly average, model over the worldwide midlatitude ionospheric data set for different seasons and solar activity conditions, TDAMI yields results comparable with the well-known empirical models of the International Radio Consultative Committee (CCIR) and the Union Radio Scientifique Internationale (URSI). The mean annual relative error in f(o)F(2) is <8% for all levels of solar activity, while the mean seasonal errors do not exceed 12%. A comparison between the model simulations and all existing vertical incidence (VI) data for the geomagnetically disturbed period October 10-11, 1988, shows that TDAMI adequately simulates the UT-latitudinal-longitudinal dependence of the ionospheric reaction to the geomagnetic disturbance. During the hours of maximum depletion in the electron density, the improvement achieved by the model is more than 70-80% compared to international reference ionosphere (IRI) global distributions (by CCIR and URSI coefficients sets). The maximum TDAMI model error is 20-25%. C1 Bulgarian Acad Sci, Inst Geophys, BU-1113 Sofia, Bulgaria. NASA, Goddard Space Flight Ctr, SSAI, Greenbelt, MD 20771 USA. RP Kilifarska, NA (reprint author), Bulgarian Acad Sci, Inst Geophys, 3 Acad G Bonchev, BU-1113 Sofia, Bulgaria. RI Ouzounov, Dimitar/A-5929-2012; OI Kilifarska, Natalya/0000-0002-1874-8610 NR 47 TC 3 Z9 3 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2001 VL 106 IS A12 BP 30415 EP 30428 DI 10.1029/2001JA001106 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 519LV UT WOS:000173728500131 ER PT J AU Hutchinson, TM Bakulin, AV Rakhmanov, AS Martin, RB Steele, CR Arnaud, SB AF Hutchinson, TM Bakulin, AV Rakhmanov, AS Martin, RB Steele, CR Arnaud, SB TI Effects of chair restraint on the strength of the tibia in rhesus monkeys SO JOURNAL OF MEDICAL PRIMATOLOGY LA English DT Article DE bending stiffness; chair-restraint; laterality; mesus monkeys (M. mulatta); tibia ID ULNAR BENDING STIFFNESS; MECHANICAL-PROPERTIES; DISUSE OSTEOPOROSIS; MACACA-MULATTA; M-NEMESTRINA; BONE; SPACEFLIGHT; VALIDATION; INVIVO; MODEL AB To determine the effects of the relative inactivity and unloading on the strength of the tibias of monkeys, Macaca mulatta, we used a non-invasive test to measure bending stiffness, or EI (Nm(2)), a mechanical property. The technique was validated by comparisons of in vivo measurements with standard measures of EI in the same bones post-mortem (r(2) = 0.95 P < 0.0001). Inter-test precision was 4.28 +/- 1.4%. Normative data in 24 monkeys, 3.0 +/- 0.7 years and 3.6 +/- 0.6 kg, revealed EI to be 16% higher in the right than left tibia (4.4 +/- 1.6 vs. 3.7 +/- 1.6 Nm(2), P < 0.05). Five monkeys, restrained in chairs for 14 days, showed decreases in EI There were no changes in EI in two chaired monkeys that lost weight during a 2-week space flight. The factors that account for both the decreases in bone mechanical properties after chair restraint at I g and lack of change after microgravity remain to be identified. Metabolic factors associated with body weight changes are suggested by our results. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Inst Biomed Problems, Moscow, Russia. Univ Calif Davis, Dept Orthopaed, Davis, CA 95616 USA. Stanford Univ, Div Appl Mech, Stanford, CA 94305 USA. RP Arnaud, SB (reprint author), NASA, Ames Res Ctr, Div Life Sci, SLR 239-11, Moffett Field, CA 94035 USA. NR 22 TC 6 Z9 7 U1 0 U2 0 PU BLACKWELL MUNKSGAARD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0047-2565 J9 J MED PRIMATOL JI J. Med. Primatol. PD DEC PY 2001 VL 30 IS 6 BP 313 EP 321 DI 10.1034/j.1600-0684.2001.300605.x PG 9 WC Veterinary Sciences; Zoology SC Veterinary Sciences; Zoology GA 526AB UT WOS:000174105300005 PM 11990531 ER PT J AU Ng, HT Fang, AP Li, J Li, SFY AF Ng, HT Fang, AP Li, J Li, SFY TI Flexible carbon nanotube membrane sensory system: A generic platform SO JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY LA English DT Article DE carbon nanotube; membrane; sensors; template growth; chemical-vapor deposition; electrochemistry; soft lithography ID ELECTRODES; CATECHOLS AB Multi-walled carbon nanotube membrane as obtained from soft lithography-mediated selective chemical-vapor deposition template approach has been successfully integrated with flexible elastomeric polydimethylsiloxane framework to fabricate microsensing devices. Two proof-of-concept experiments, namely high-sensitivity chemical gas sensing and electrochemical detection have been performed to demonstrate its potential as a useful generic platform for general purposes sensory system. C1 Inst Mat Res & Engn, Singapore 117602, Singapore. Natl Univ Singapore, Dept Chem, Singapore 117543, Singapore. RP Li, J (reprint author), NASA, Ames Res Ctr, MS229-1, Moffett Field, CA 94035 USA. RI Fang, Aiping/D-1229-2010; Li, Sam/J-3113-2013; Li, Jun/H-7771-2013 OI Li, Sam/0000-0002-2092-9226; Li, Jun/0000-0002-3689-8946 NR 29 TC 16 Z9 17 U1 0 U2 14 PU AMER SCIENTIFIC PUBLISHERS PI STEVENSON RANCH PA 25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USA SN 1533-4880 J9 J NANOSCI NANOTECHNO JI J. Nanosci. Nanotechnol. PD DEC PY 2001 VL 1 IS 4 BP 375 EP 379 DI 10.1166/jnn.2001.056 PG 5 WC Chemistry, Multidisciplinary; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Chemistry; Science & Technology - Other Topics; Materials Science; Physics GA 529GL UT WOS:000174291600002 PM 12914076 ER PT J AU Theys, MD Ali, S Siegel, HJ Chandy, M Hwang, K Kennedy, K Sha, L Shin, KG Snir, M Snyder, L Sterling, T AF Theys, MD Ali, S Siegel, HJ Chandy, M Hwang, K Kennedy, K Sha, L Shin, KG Snir, M Snyder, L Sterling, T TI What are the top ten most influential parallel and distributed processing concepts of the past millenium? SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article; Proceedings Paper CT International Parallel and Distribute Processing Symposium CY MAY 03, 2000 CL CANCUN, MEXICO AB This is a report on a panel titled "What are the top ten most influential parallel and distributed processing concepts of the last millennium'?" that was held at the IEEE Computer Society sponsored "14th International Parallel and Distributed Processing Symposium (IPDPS 2000)." The panelists were chosen to represent a variety of perspectives and technical areas. After the panelists had presented their choices for the top ten, an open discussion was held among the audience and panelists. At the end of the discussion, a ballot was distributed for the audience to vote on the top ten concepts (in arbitrary order). The voting identified the following ten most influential parallel and distributed processing concepts of the last millennium: (1) Amdahl's law and scalability, (2) Arpanet and Internet, (3) pipelining, (4) divide and conquer approach, (5) multiprogramming. (6) synchronization (including semaphores), (7) load balancing, (8) message passing and packet switching, (9) cluster computing, and (10) multithreaded (lightweight) program execution. (C) 2001 Academic Press. C1 Univ Illinois, Dept Comp Sci MC 152, Chicago, IL 60607 USA. Purdue Univ, Sch Elect & Comp Engn, W Lafayette, IN 47907 USA. Colorado State Univ, Dept Elect & Comp Engn, Ft Collins, CO 80523 USA. CALTECH, Comp Sci Dept 256 80, Pasadena, CA 91125 USA. Univ So Calif, Dept Elect Engn Syst, Los Angeles, CA 90089 USA. Rice Univ, HiPerSoft MS41, Houston, TX 77005 USA. Univ Illinois, Urbana, IL 61801 USA. Univ Michigan, Dept Elect & Comp Sci, Real Time Comp Lab, Ann Arbor, MI 48109 USA. IBM Corp, Thomas J Watson Res Ctr, Yorktown Hts, NY 10598 USA. Univ Washington, Dept Comp Sci & Engn, Seattle, WA 98195 USA. NASA, Jet Prop Lab, Ctr Adv Comp Res, Pasadena, CA 91125 USA. RP Theys, MD (reprint author), Univ Illinois, Dept Comp Sci MC 152, 851 S Morgan St,Room 1120, Chicago, IL 60607 USA. RI Snir, Marc/B-1050-2009 OI Snir, Marc/0000-0002-3504-2468 NR 0 TC 2 Z9 2 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD DEC PY 2001 VL 61 IS 12 BP 1827 EP 1841 DI 10.1006/jpdc.2001.1767 PG 15 WC Computer Science, Theory & Methods SC Computer Science GA 514DR UT WOS:000173423400007 ER PT J AU Parusel, ABJ Pohorille, A AF Parusel, ABJ Pohorille, A TI A semiempirical study of the optimized ground and excited state potential energy surfaces of retinal and its protonated Schiff base SO JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY LA English DT Article DE semiempirical study; optimized excited states; potential energy surface; retinal; protonated Schiff base ID BACTERIORHODOPSIN; RHODOPSIN; PHOTOISOMERIZATION; ISOMERIZATION; CHROMOPHORES; DYNAMICS; SPECTRA; MODEL AB The electronic ground and first excited states of retinal and its Schiff base are optimized for the first time using the semiempirical AM1 Hamiltonian. The barrier for rotation about the C-11-C-12 double bond is characterized by variation of both the twist angle delta (C-10-C-11-C-12-C-13) and the bond length d(C-11-C-12). The potential energy surface is obtained by varying these two parameters, The calculated ground state rotational barrier is equal to 15.6 kcal/mol for retinal and 20.5 kcal/mol for its Schiff base. The all-trans conformation is more stable by 3.7 kcal/mol than the 11-cis geometry. For the first excited state, S-1. the 90 degrees twisted geometry represents a saddle point for retinal with the rotational barrier of 14.6 kcal/mol. In contrast, this conformation is an energy minimum for the Schiff base. It can be easily reached at room temperature from the planar minima since it is separated from them by a barrier of only 0.6 kcal/mol. The 90 degrees minimum conformation is more stable than the all-trans by 8.6 kcal/mol. We are thus able to present a reaction path on the S-1 surface of the retinal Schiff base with an almost barrierless geometrical relaxation into a twisted minimum geometry, as observed experimentally. The character of the ground and first excited singlet states underscores the need for the inclusion of double excitations in the calculations. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Inst Theoret Chem & Struct Biol, Rennweg 95B, A-1030 Vienna, Austria. EM andreas.parusel@univie.ac.at NR 20 TC 4 Z9 4 U1 2 U2 7 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 1011-1344 J9 J PHOTOCH PHOTOBIO B JI J. Photochem. Photobiol. B-Biol. PD DEC 1 PY 2001 VL 65 IS 1 BP 13 EP 21 DI 10.1016/S1011-1344(01)00238-X PG 9 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA 505TK UT WOS:000172931500003 PM 11748000 ER PT J AU Ray, RD AF Ray, RD TI Resonant third-degree diurnal tides in the seas off western Europe SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID NORMAL-MODES; WORLD OCEAN AB Third-degree diurnal tides are estimated from long time series of sea level measurements at three North Atlantic tide gauges. Although their amplitudes are only a few millimeters or less, their admittances are far larger than those of second-degree diurnal tides, just as Cartwright discovered for the M-1 constituent. The tides are evidently resonantly enhanced owing to high spatial correlation between the third-degree spherical harmonic of the tidal potential and a near-diurnal oceanic normal mode that is most pronounced in the North Atlantic. By estimating the ocean tidal response across the diurnal band (five tidal constituents plus nodal modulations), the period and Q of this mode and one nearby mode are estimated. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Space Geodesy Branch, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, Terr Phys Lab, Space Geodesy Branch, Code 926, Greenbelt, MD 20771 USA. EM richard.ray@gsfc.nasa.gov RI Ray, Richard/D-1034-2012 NR 8 TC 6 Z9 6 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-3670 EI 1520-0485 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD DEC PY 2001 VL 31 IS 12 BP 3581 EP 3586 DI 10.1175/1520-0485(2001)031<3581:RTDDTI>2.0.CO;2 PG 6 WC Oceanography SC Oceanography GA 505FT UT WOS:000172903300014 ER PT J AU Lincoln, JE Morgan, RJ Shin, EE AF Lincoln, JE Morgan, RJ Shin, EE TI Effect of thermal history on the deformation and failure of polyimides SO JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS LA English DT Article DE polyimides; structure-property relations; fracture ID BISMALEIMIDE COMPOSITE MATRICES; TEMPERATURE SIZING MATERIAL; IMIDE OLIGOMERS; X-RAY; MECHANICAL-PROPERTIES; PHENYLETHYNYL; CRYSTALLIZATION; PETI-5; POLYCARBONATE; PERFORMANCE AB Thermal-processing structure-property relationships for polyetherimide (PEI), poly(4,4'-oxydiphenylene pyromellitimide) (POPPI), and phenylethynyl-terminated imide (PETI-5) composite matrices are reported from a fundamental perspective. For thermoplastic PEI, deformation and failure depend primarily on free volume as evidenced by moisture-absorption, mechanical-property, and mass-density changes as a function of annealing. The deformation of POPPI can be divided into the following three regimes as a function of annealing temperature: (1) physical aging-induced glassy state free-volume decreases, (2) thermally activated microvoid collapse, and (3) chemical degradation. In the case of PETI-5, macroscopic defects, free volume, and polymer morphology control deformation. The effects of residual crystallinity on deformation are reported, and it is shown that mechanical toughness can be significantly decreased upon annealing below the glass-transition temperature. (C) 2001 John Wiley & Sons, Inc.*. C1 USAF, Polymer Matrix Composites Res Team, Mat & Mfg Directorate, MLBC, Wright Patterson AFB, OH 45433 USA. Texas A&M Univ, Polymer Technol Ctr, Dept Mech Engn, College Stn, TX 77843 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP USAF, Polymer Matrix Composites Res Team, Mat & Mfg Directorate, MLBC, 2941 P St,RM 136, Wright Patterson AFB, OH 45433 USA. EM jason.lincoln@wpafb.af.mil NR 51 TC 14 Z9 14 U1 1 U2 7 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0887-6266 EI 1099-0488 J9 J POLYM SCI POL PHYS JI J. Polym. Sci. Pt. B-Polym. Phys. PD DEC 1 PY 2001 VL 39 IS 23 BP 2947 EP 2959 DI 10.1002/polb.10043 PG 13 WC Polymer Science SC Polymer Science GA 492EG UT WOS:000172155000003 ER PT J AU Florentine, FA Hillman, JJ AF Florentine, FA Hillman, JJ TI Unique lighting enables NASA infrared camera to analyze the Star Spangled Banner SO JOURNAL OF THE ILLUMINATING ENGINEERING SOCIETY LA English DT Article AB The Smithsonian's National Museum of American History has embarked on a preservation project for the Star Spangled Banner, the Flag that inspired the national anthem. The Flag is approximately 8 x 11 m (26 x 36 ft). To full understand the physical state of this national icon, the National Aeronautics and Space Administration's Goddard Space Flight Center imaged and analyzed the Hag with a camera normally used for ground-based astronomy and future space missions, which was sensitive to the infrared region of the electromagnetic spectrum. The camera, Acoustic-Optic Imaging Spectrometer (AimS), required unique lighting to record its images while not damaging the national treasure. The project's goal was to measure the distribution of moisture and oil stains in the wool fibers of the Flag. The lighting solution - providing infrared light without causing harm to the fabric - combined experts from many disciplines. In cooperation with the lighting designer, NASA Goddard's camera group took sample lighting luminaires and analyzed the optics. The Goddard group also performed its own transmission curve analysis of various filters to determine the most optimum filterfor the AimS system. This paper will present those findings of each analysis phase. Implementation of the lighting for the two-weeks of photography included a motorized lighting system to adjust the vertical height of the luminaires and a dimming system that enabled the camera operators to illuminate I sq m of the Hag while photographing. Seventy-two separate image cubes were made each containing up to 100 images. This paper will summarize the findings of the project. C1 Smithsonian Inst, Natl Air & Space Museum, Washington, DC 20560 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Florentine, FA (reprint author), Smithsonian Inst, Natl Air & Space Museum, Washington, DC 20560 USA. NR 6 TC 0 Z9 0 U1 0 U2 1 PU ILLUMINAT ENG SOC NORTH AMER PI NEW YORK PA 120 WALL ST, 17TH FL, NEW YORK, NY 10005-4001 USA SN 0099-4480 J9 J ILLUM ENG SOC JI J. Illum. Eng. Soc. PD WIN PY 2001 VL 30 IS 1 BP 17 EP + PG 10 WC Optics SC Optics GA 750TV UT WOS:000187015100002 ER PT J AU Lee, C Choi, DS Park, HR Kim, CS Wang, KL AF Lee, C Choi, DS Park, HR Kim, CS Wang, KL TI Side contact single electron devices for integrated circuit SO JOURNAL OF THE KOREAN PHYSICAL SOCIETY LA English DT Article; Proceedings Paper CT 10th Seoul International Symposium on the Physics of Semiconductors and Applications CY NOV 01-03, 2000 CL CHEJU, SOUTH KOREA ID TRANSISTOR AB A single electron transistor (SET) on SiGe/Si double-barrier structure has been studied with side contact. The progress of Si/SiGe vertical structure indicates that a new concept can be introduced to the Si-ultralarge scale integrated circuits field. In the Si/SiGe transistors, we can more easily control current flowing from drain to source by gate voltage than in any other three terminal devices. Drain and source regions are one dimensional, the well region (gate region) of device is zero dimensional with reverse gate bias. The resonant tunneling (one dimension to zero dimension, zero dimension to one dimension) and current-voltage curves are investigated in two-dimensional quantum model. The effect of delta doping results in shifting and reducing the peak value of transmission probabilities. We found a current enhancement in delta doped heterostructure at low temperatures. We calculate the posibility of Si single electron transistor in a two-dimensional simulation of the resonant tunneling transistor. C1 Honam Univ, Kwangju 506714, South Korea. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Mokpo Univ, Dept Phys, Mokpo 534729, South Korea. Chonnam Natl Univ, Dept Phys, Kwangju 500757, South Korea. Univ Calif Los Angeles, Los Angeles, CA 90095 USA. RP Lee, C (reprint author), Honam Univ, Kwangju 506714, South Korea. RI Choi, Daniel/A-8181-2017 NR 10 TC 0 Z9 0 U1 1 U2 1 PU KOREAN PHYSICAL SOC PI SEOUL PA 635-4, YUKSAM-DONG, KANGNAM-KU, SEOUL 135-703, SOUTH KOREA SN 0374-4884 J9 J KOREAN PHYS SOC JI J. Korean Phys. Soc. PD DEC PY 2001 VL 39 SU S BP S442 EP S446 PG 5 WC Physics, Multidisciplinary SC Physics GA 506KC UT WOS:000172968700102 ER PT J AU DellaCorte, C AF DellaCorte, C TI Houston - We'll have no problem SO LUBRICATION ENGINEERING LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Washington, DC 20546 USA. RP DellaCorte, C (reprint author), NASA, Glenn Res Ctr, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD DEC PY 2001 VL 57 IS 12 BP 3 EP + PG 2 WC Engineering, Mechanical SC Engineering GA 501XY UT WOS:000172712400001 ER PT J AU Donohue, MJ Boland, RC Sramek, CM Antonelis, GA AF Donohue, MJ Boland, RC Sramek, CM Antonelis, GA TI Derelict fishing gear in the Northwestern Hawaiian Islands: Diving surveys and debris removal in 1999 confirm threat to coral reef ecosystems SO MARINE POLLUTION BULLETIN LA English DT Article DE marine debris; contaminants; Hawaiian monk seal; coral reef; fishing; Northwestern Hawaiian Islands ID CONTINENTAL-SHELF; MARINE DEBRIS; ABUNDANCE; NORTH AB Marine debris threatens Northwestern Hawaiian Islands' (NWHI) coral reef ecosystems. Debris, a contaminant, entangles and kills endangered Hawaiian monk seals (Monachus schauinslandi), coral, and other wildlife. We describe a novel multi-agency effort using divers to systematically survey and remove derelict fishing gear from two NWHI in 1999. 14 t of derelict fishing gear were removed and debris distribution, density, type and fouling level documented at Lisianski Island and Pearl and Hermes Atoll. Reef debris density ranged from 3.4 to 62.2 items/ km(2). Trawl netting was the most frequent debris type encountered (88%) and represented the greatest debris component recovered by weight (35%), followed by monofilament gillnet (34%), and maritime line (23%). Most debris recovered, 72%, had light or no fouling, suggesting debris may have short oceanic circulation histories. Our study demonstrates that derelict fishing gear poses a persistent threat to the coral reef ecosystems of the Hawaiian Archipelago. Published by Elsevier Science Ltd. C1 NOAA, Commissioned Corps, Natl Marine Fisheries Serv, Honolulu Lab, Honolulu, HI 96822 USA. Univ Hawaii, Corp Res, Joint Inst Marine & Atmospher Res, Honolulu, HI 96822 USA. RP NOAA, Commissioned Corps, Natl Marine Fisheries Serv, Honolulu Lab, 2570 Dole St, Honolulu, HI 96822 USA. EM mary.donohue@noaa.gov NR 35 TC 86 Z9 97 U1 2 U2 22 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0025-326X EI 1879-3363 J9 MAR POLLUT BULL JI Mar. Pollut. Bull. PD DEC PY 2001 VL 42 IS 12 BP 1301 EP 1312 DI 10.1016/S0025-326X(01)00139-4 PG 12 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 507VP UT WOS:000173052200018 PM 11827117 ER PT J AU Argon, AS Yi, J Sayir, A AF Argon, AS Yi, J Sayir, A TI Creep resistance of directionally solidified ceramic eutectics of Al2O3/c-ZrO2 with sub-micron columnar morphologies SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article; Proceedings Paper CT 12th Meeting of the International Conference on the Strength of Materials (ICSMA 12) CY AUG 27-SEP 01, 2000 CL ASILOMAR, CALIFORNIA DE ceramic cutectics; creep resistance; Al2O3; cubic ZrO2 ID SINGLE-CRYSTALS; TEMPERATURE AB Directionally solidified laser float-zone-processed ceramic eutectics. having columnar morphologies made up of colonies of fibrilar and lamellar components of cubic Zr0(2) surrounded by a component of Al(2)0(3) and having sub-micron morphological wave length. have a potential for remarkable creep resistance in the 1400degreesC temperature range when stressed parallel to the growth direction. The bulk creep response of both single crystalline Al(2)0(3) and cubic Zr0(2) have been investigated extensively at this temperature and have shown no extraordinary promise for structural application. However, when directionally solidified and constituted in columnar eutectic morphologies with sub-micron wave length of phase dimensions, the restricted plasticity behavior that should occur can result in remarkable creep resistance. In many respects, this topology of constrained plasticity is expected to resemble that found in the CMSX-III super alloy single crystals. (C) 2001 Elsevier Science B.V. All rights reserved. C1 MIT, Dept Mech Engn, Cambridge, MA 02139 USA. NASA, John Glenn Res Ctr, Cleveland, OH 44135 USA. RP Argon, AS (reprint author), MIT, Dept Mech Engn, 77 Massachusetts Ave, Cambridge, MA 02139 USA. NR 8 TC 19 Z9 19 U1 2 U2 11 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD DEC PY 2001 VL 319 SI SI BP 838 EP 842 DI 10.1016/S0921-5093(00)02033-5 PG 5 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 510ME UT WOS:000173211200172 ER PT J AU Trombka, JI Nittler, LR Starr, RD Evans, LG McCoy, TJ Boynton, WV Burbine, TH Bruckner, J Gorenstein, P Squyres, SW Reedy, RC Goldsten, JO Lim, L Hurley, K Clark, PE Floyd, SR McClanahan, TR McCartney, E Branscomb, J Bhangoo, JS Mikheeva, I Murphy, ME AF Trombka, JI Nittler, LR Starr, RD Evans, LG McCoy, TJ Boynton, WV Burbine, TH Bruckner, J Gorenstein, P Squyres, SW Reedy, RC Goldsten, JO Lim, L Hurley, K Clark, PE Floyd, SR McClanahan, TR McCartney, E Branscomb, J Bhangoo, JS Mikheeva, I Murphy, ME TI The NEAR-Shoemaker x-ray/gamma-ray spectrometer experiment: Overview and lessons learned SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID ASTEROID RENDEZVOUS MISSION AB The near-Earth asteroid rendezvous (NEAR)-Shoemaker remote-sensing x-ray/gamma-ray spectrometer (XGRS) completed more than a year of operation in orbit and on the surface of 433 Eros. Elemental compositions for a number of regions on the surface of Eros have been derived from analyses of the characteristic x-ray and gamma-ray emission spectra. The NEAR XGRS detection system was included as part of the interplanetary network (IPN) for the detection and localization of gamma-ray bursts (GRBs). Preliminary results for both the elemental composition of the surface of Eros and the detection of GRBs have been obtained. In addition to the science results, the design and operation of the NEAR XGRS is considered. Significant information important for the design of future remote sensing XGRS systems has been obtained and evaluated. We focus on four factors that became particularly critical during NEAR: (1) overall spacecraft design, (2) selection of materials, (3) increase of the signal-to-noise ratio and (4) knowledge of the incident solar x-ray spectrum. C1 Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20016 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Comp Sci Corp, Laurel, MD 20701 USA. RP Trombka, JI (reprint author), Goddard Space Flight Ctr, Extraterr Phys Lab, Code 691, Greenbelt, MD 20771 USA. RI Lim, Lucy/C-9557-2012; OI Lim, Lucy/0000-0002-9696-9654; Reedy, Robert/0000-0002-2189-1303 NR 29 TC 15 Z9 15 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD DEC PY 2001 VL 36 IS 12 BP 1605 EP 1616 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 513QG UT WOS:000173389200006 ER PT J AU Evans, LG Starr, RD Bruckner, J Reedy, RC Boynton, WV Trombka, JI Goldstein, JO Masarik, J Nittler, LR McCoy, TJ AF Evans, LG Starr, RD Bruckner, J Reedy, RC Boynton, WV Trombka, JI Goldstein, JO Masarik, J Nittler, LR McCoy, TJ TI Elemental composition from gamma-ray spectroscopy of the NEAR-Shoemaker landing site on 433 Eros SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID SPECTROMETER AB Elemental composition and composition ratios derived from gamma-ray measurements collected by the NEAR-Shoemaker spacecraft while on the surface of 433 Eros are reported. Performance of the gamma-ray spectrometer (GRS) during cruise and orbit is reviewed. The best gamma-ray data were collected on the surface of Eros after the spacecraft's controlled descent on 2001 February 12. Methods used in spectral analysis, to convert peak areas to incident photons, and photons to elemental composition are described in some detail. The elemental abundance of K and the Mg/Si, Fe/Si, Si/O and Fe/O abundance ratios were determined. The Mg/Si and Si/O ratios and the K abundance are roughly chondritic, but the Fe/Si and Fe/O ratios are low compared to expected chondritic values. Three possible explanations for the apparent Fe depletion are considered. C1 Comp Sci Corp, Sci Programs, Lanham, MD 20706 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Max Planck Inst Chem, D-55020 Mainz, Germany. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. RP Evans, LG (reprint author), Comp Sci Corp, Sci Programs, Lanham, MD 20706 USA. NR 31 TC 41 Z9 41 U1 0 U2 3 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD DEC PY 2001 VL 36 IS 12 BP 1639 EP 1660 PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 513QG UT WOS:000173389200008 ER PT J AU McCoy, TJ Burbine, TH McFadden, LA Starr, RD Gaffey, MJ Nittler, LR Evans, LG Izenberg, N Lucey, PG Trombka, JI Bell, JF Clark, BE Clark, PE Squyres, SW Chapman, CR Boynton, WV Veverka, J AF McCoy, TJ Burbine, TH McFadden, LA Starr, RD Gaffey, MJ Nittler, LR Evans, LG Izenberg, N Lucey, PG Trombka, JI Bell, JF Clark, BE Clark, PE Squyres, SW Chapman, CR Boynton, WV Veverka, J TI The composition of 433 Eros: A mineralogical-chemical synthesis SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID ASTEROID RENDEZVOUS MISSION; RAY/GAMMA-RAY SPECTROMETER; NEAR-INFRARED SPECTROMETER; MULTISPECTRAL IMAGER; BODIES AB The near-Earth asteroid rendezvous (NEAR) mission carried x-ray/gamma-ray spectrometers and multi-spectral imager/near-infrared spectrometer instrument packages which gave complementary information on the chemistry and mineralogy, respectively, of the target asteroid 433 Eros. Synthesis of these two data sets provides information not available from either alone, including the abundance of non-mafic silicates, metal and sulfide minerals. We have utilized four techniques to synthesize these data sets. Venn diagrams, which examine overlapping features in two data sets, suggest that the best match for 433 Eros is an ordinary chondrite, altered at the surface of the asteroid, or perhaps a primitive achondrite derived from material mineralogically similar to these chondrites. Normalized element distributions preclude FeO-rich pyroxenes and suggest that the x-ray and gamma-ray data can be reconciled with a common silicate mineralogy by inclusion of varying amounts of metal. Non-native mineralogy cannot be applied to these data sets owing to uncertainties in oxygen abundance and lack of any constraints on the abundance of sodium. Matrix inversion for simultaneous solution of mineral abundances yields reasonable results for the x-ray-derived bulk composition, but seems to confirm the inconsistency between mineral compositions and orthopyroxene/clinopyroxene ratios. A unique solution does not seem possible in synthesizing these multiple data sets. Future missions including a lander to fully characterize regolith distribution and sample return would resolve the types of problems faced in synthesizing the NEAR data. C1 Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. Univ Maryland, Dept Agron, College Pk, MD 20742 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Rensselaer Polytech Inst, Dept Earth & Enviromm Sci, Troy, NY 12180 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Comp Sci Corp, Sci Programs, Lanham, MD 20706 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. SW Res Inst, Boulder, CO 80302 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RP McCoy, TJ (reprint author), Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. RI McFadden, Lucy-Ann/I-4902-2013; Izenberg, Noam/F-3952-2015 OI McFadden, Lucy-Ann/0000-0002-0537-9975; Izenberg, Noam/0000-0003-1629-6478 NR 35 TC 46 Z9 46 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD DEC PY 2001 VL 36 IS 12 BP 1661 EP 1672 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 513QG UT WOS:000173389200009 ER PT J AU Nittler, LR Starr, RD Lim, L McCoy, TJ Burbine, TH Reedy, RC Trombka, JI Gorenstein, P Squyres, SW Boynton, WV McClanahan, TP Bhangoo, JS Clark, PE Murphy, ME Killen, R AF Nittler, LR Starr, RD Lim, L McCoy, TJ Burbine, TH Reedy, RC Trombka, JI Gorenstein, P Squyres, SW Boynton, WV McClanahan, TP Bhangoo, JS Clark, PE Murphy, ME Killen, R TI X-ray fluorescence measurements of the surface elemental composition of asteroid 433 Eros SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID EMISSION MEASURE; ORDINARY CHONDRITES; CALCIUM ABUNDANCE; SPECTROMETER; SPECTROSCOPY; TEMPERATURE; 433-EROS; MISSION AB We report major element ratios determined for the S-class asteroid 43 3 Eros using remote-sensing x-ray fluorescence spectroscopy with the near-Earth asteroid rendezvous Shoemaker x-ray spectrometer (XRS). Data analysis techniques and systematic errors are described in detail. Data acquired during five solar flares and during two extended "quiet Sun" periods are presented; these results sample a representative portion of the asteroid's surface. Although systematic uncertainties are potentially large, the most internally consistent and plausible interpretation of the data is that Eros has primitive Mg/Si, Al/Si, Ca/Si and Fe/Si ratios, closely similar to H or R chondrites. Global differentiation of the asteroid is ruled out. The S/Si ratio is much lower than that of chondrites, probably reflecting impact-induced volatilization and/or photo- or ion-induced sputtering of sulfur at the surface of the asteroid. An alternative explanation for the low S/Si ratio is that it reflects a limited degree of melting with loss of an FeS-rich partial melt. Size-sorting processes could lead to segregation of Fe-Ni metal from silicates within the regolith of Eros; this could indicate that the Fe/Si ratios determined by the x-ray spectrometer are not representative of the bulk Eros composition. C1 Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Cornell Univ, Ithaca, NY 14853 USA. Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. Univ Arizona, Dept Planetary Sci, Tucson, AZ 85721 USA. SW Res Inst, San Antonio, TX 78228 USA. RP Nittler, LR (reprint author), Carnegie Inst Washington, Dept Terr Magnetism, 5241 Broad Branch Rd NW, Washington, DC 20015 USA. EM lrn@dtm.ciw.edu RI Lim, Lucy/C-9557-2012; Killen, Rosemary/E-7127-2012; OI Lim, Lucy/0000-0002-9696-9654; Reedy, Robert/0000-0002-2189-1303 NR 55 TC 67 Z9 69 U1 0 U2 5 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD DEC PY 2001 VL 36 IS 12 BP 1673 EP 1695 PG 23 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 513QG UT WOS:000173389200010 ER PT J AU Magri, C Consolmagno, GJ Ostro, SJ Benner, LAM Beeney, BR AF Magri, C Consolmagno, GJ Ostro, SJ Benner, LAM Beeney, BR TI Radar constraints on asteroid regolith properties using 433 Eros as ground truth SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID MAINBELT ASTEROIDS; METEORITES; POROSITY; DENSITY; GOLDSTONE; 433-EROS; SURFACE; ARECIBO; MARS AB Radar data enable us to estimate an asteroid's near-surface bulk density, thus providing a joint constraint on near-surface porosity and solid density. We investigate two different approaches to simplifying this joint constraint: estimating solid densities by assuming uniform porosities for all asteroids; and estimating porosities by assuming uniform mineralogy within each taxonomic class. Methods used to estimate asteroids' near-surface solid densities from radar data have not previously been calibrated via independent estimates. Recent spacecraft results on the chondritic nature of 433 Eros now permit such a check, and also support porosity estimation for S-class objects. We use radar albedos and polarization ratios estimated for 36 main-belt asteroids and nine near-Earth asteroids to estimate near-surface solid densities using two methods, one of which is similar to the uncalibrated algorithms used in previous studies, the other of which treats Eros as a calibrator. We also derive porosities for the same sample by assigning solid densities for each taxonomic class in advance. Density-estimation results obtained for Eros itself are consistent with the uncalibrated method being valid in the mean; those derived for the full sample imply that uncalibrated solid densities are, at most, a few tens of percent too large on average. However, some derived densities are extremely low, whereas most porosity estimates are physically plausible. We discuss the relative merits of these two approaches. C1 Univ Maine, Farmington, ME 04938 USA. Univ Arizona, Steward Observ, Vatican Observ Res Grp, Tucson, AZ 85721 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Magri, C (reprint author), Univ Maine, 173 High St,Preble Hall, Farmington, ME 04938 USA. NR 35 TC 43 Z9 43 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD DEC PY 2001 VL 36 IS 12 BP 1697 EP 1709 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 513QG UT WOS:000173389200011 ER PT J AU Done, C Nayakshin, S AF Done, C Nayakshin, S TI Testing models of X-ray reflection from irradiated discs SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; line : formation; radiation mechanisms : non-thermal; radiative transfer; X-rays : general ID ADVECTION-DOMINATED ACCRETION; IRON LINE REVERBERATION; ACTIVE GALACTIC NUCLEI; CYGNUS X-1; BLACK-HOLES; DISKS; BINARIES; CORONAE; MASS; NOVA-MUSCAE-1991 AB We model the reflected spectrum expected from localized magnetic flares above an ionized accretion disc. We concentrate on the case of very luminous magnetic flares above a standard accretion disc extending down to the last stable orbit, and use a simple parametrization to allow for an X-ray-driven wind. Full disc spectra including relativistic smearing are calculated. When fitted with the constant-density reflection models, these spectra give both a low reflected fraction and a small linewidth as seen in the hard spectra from galactic black hole binaries and active galactic nuclei. We fit our calculated spectra to real data from the low/hard state of Nova Muscae and Cyg X-1 and show that these models give comparable chi (2) to those obtained from the constant-density reflection models, which implied a truncated disc. This explicitly demonstrates that the data are consistent either with magnetic flares above an ionized disc extending down to the last stable orbit around a black hole, or with non-ionized, truncated discs. C1 Univ Durham, Dept Phys, Durham DH1 3LE, England. NASA, Goddard Space Flight Ctr, USRA, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. Max Planck Inst Astrophys, D-85741 Garching, Germany. RP Done, C (reprint author), Univ Durham, Dept Phys, South Rd, Durham DH1 3LE, England. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 47 TC 19 Z9 19 U1 0 U2 0 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD DEC 1 PY 2001 VL 328 IS 2 BP 616 EP 622 DI 10.1046/j.1365-8711.2001.04917.x PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 505PV UT WOS:000172925500024 ER PT J AU Liske, J Williger, GM AF Liske, J Williger, GM TI The proximity effect in a close group of QSOs SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE intergalactic medium; quasars : absorption lines; diffuse radiation ID LY-ALPHA FOREST; LARGE-SCALE STRUCTURE; HIGH-REDSHIFT QUASARS; FIELD MULTICOLOR SURVEY; ACTIVE GALACTIC NUCLEI; ULTRAVIOLET EXTINCTION; BACKGROUND-RADIATION; ABSORPTION SYSTEMS; CONTINUUM SLOPES; HIGH-RESOLUTION AB We present an analysis of the proximity effect in a sample of 10 2-Angstrom -resolution QSO spectra of the Ly alpha forest at [z] = 2.9. Rather than investigating variations in the number density of individual absorption lines, we employ a novel technique that is based on the statistics of the transmitted flux itself. We confirm the existence of the proximity effect at the > 99 per cent confidence level. We derive a value for the mean intensity of the extragalactic background radiation at the Lyman limit of J = 3.5(-1.3)(+3.5) x 10(-22) erg s(-1) cm(-2) Hz(-1) sr(-1). This value assumes that QSO redshifts measured from high-ionization lines differ from the true systemic redshifts by Deltav approximate to 800 km s(-1). We find evidence at a level of 2.6 sigma that the significance of the proximity effect is correlated with QSO Lyman limit luminosity. Allowing for known QSO variability, the significance of the correlation reduces to 2.1 sigma. The QSOs form a close group on the sky and the sample is thus well suited for an investigation of the foreground proximity effect, where the Lya forest of a background QSO is influenced by the UV radiation from a nearby foreground QSO. From the complete sample we find no evidence for the existence of this effect, implying either that J > 20 x 10(-22) erg s(-1) cm(-2) Hz(-1) sr(-1) or that QSOs emit at least a factor of 1.4 less ionizing radiation in the plane of the sky than along the line of sight to Earth. We do, however, find one counter-example. Our sample includes the fortunate constellation of a foreground QSO surrounded by four nearby background QSOs. These four spectra all show underdense absorption within +/- 3000 km s(-1) of the redshift of the foreground QSO. C1 Univ New S Wales, Sch Phys, Sydney, NSW 2052, Australia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Univ New S Wales, Sch Phys, Sydney, NSW 2052, Australia. EM jol@phys.unsw.edu.au NR 77 TC 38 Z9 38 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0035-8711 EI 1365-2966 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD DEC 1 PY 2001 VL 328 IS 2 BP 653 EP 668 DI 10.1046/j.1365-8711.2001.04908.x PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 505PV UT WOS:000172925500028 ER PT J AU Yoshida, N Sheth, RK Diaferio, A AF Yoshida, N Sheth, RK Diaferio, A TI Non-Gaussian cosmic microwave background temperature fluctuations from peculiar velocities of clusters SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE gravitation; methods : N-body simulations; galaxies : clusters : general; cosmic microwave background; large-scale structure of Universe ID DARK-MATTER HALOES; DENSITY PROFILE; RADIATION; GALAXIES; MODELS AB We use numerical simulations of a (480 Mpc h(-1))(3) volume to show that the distribution of peak heights in maps of the temperature fluctuations from the kinematic and thermal Sunyaev-Zeldovich (SZ) effects will be highly non-Gaussian, and very different from the peak-height distribution of a Gaussian random field. We then show that it is a good approximation to assume that each peak in either SZ effect is associated with one and only one dark matter halo. This allows us to use our knowledge of the properties of haloes to estimate the peak-height distributions. At fixed optical depth, the distribution of peak heights resulting from the kinematic effect is Gaussian, with a width that is approximately proportional to the optical depth; the non-Gaussianity comes from summing over a range of optical depths. The optical depth is an increasing function of halo mass and the distribution of halo speeds is Gaussian, with a dispersion that is approximately independent of halo mass. This means that observations of the kinematic effect can be used to put constraints on how the abundance of massive clusters evolves, and on the evolution of cluster velocities. The non-Gaussianity of the thermal effect, on the other hand, comes primarily from the fact that, on average, the effect is larger in more massive haloes, and the distribution of halo masses is highly non-Gaussian. We also show that because haloes of the same mass may have a range of density and velocity dispersion profiles, the relation between halo mass and the amplitude of the thermal effect is not deterministic, but has some scatter. C1 Max Planck Inst Astrophys, D-85748 Garching, Germany. NASA, Fermilab Astrophys Grp, Batavia, IL 60510 USA. Univ Turin, Dipartimento Fis Gen Amedeo Avogadro, I-10124 Turin, Italy. RP Yoshida, N (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St,MS-51, Cambridge, MA 02138 USA. RI Yoshida, Naoki/A-4305-2011 NR 23 TC 107 Z9 107 U1 0 U2 1 PU BLACKWELL PUBLISHING LTD PI OXFORD PA 9600 GARSINGTON RD, OXFORD OX4 2DG, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD DEC 1 PY 2001 VL 328 IS 2 BP 669 EP 677 DI 10.1046/j.1365-8711.2001.04899.x PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 505PV UT WOS:000172925500029 ER PT J AU Werder, T Walther, JH Jaffe, RL Halicioglu, T Noca, F Koumoutsakos, P AF Werder, T Walther, JH Jaffe, RL Halicioglu, T Noca, F Koumoutsakos, P TI Molecular dynamics simulation of contact angles of water droplets in carbon nanotubes SO NANO LETTERS LA English DT Article ID SCANNING FORCE MICROSCOPY; ADSORPTION; MODEL AB We study the behavior of water droplets confined in a carbon nanotube by means of parallel molecular dynamics simulations. We report radial density profiles, radial hydrogen bond distributions, and contact angles for tube radii ranging from 12.5 to 37.5 Angstrom and for droplets containing up to 4632 water molecules. Our results indicate nonwetting behavior of the pristine CNT at room temperatures. C1 Swiss Fed Inst Technol, Inst Computat Sci, CH-8092 Zurich, Switzerland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Eloret Corp, Sunnyvale, CA 94086 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Werder, T (reprint author), Swiss Fed Inst Technol, Inst Computat Sci, Weinbergstr 43, CH-8092 Zurich, Switzerland. RI Koumoutsakos, Petros/A-2846-2008; Walther, Jens/D-9549-2015 OI Koumoutsakos, Petros/0000-0001-8337-2122; Walther, Jens/0000-0001-8100-9178 NR 22 TC 135 Z9 136 U1 11 U2 101 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1530-6984 J9 NANO LETT JI Nano Lett. PD DEC PY 2001 VL 1 IS 12 BP 697 EP 702 DI 10.1021/nl015640u PG 6 WC Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Chemistry; Science & Technology - Other Topics; Materials Science; Physics GA 525NN UT WOS:000174078000006 ER PT J AU Mavriplis, DJ AF Mavriplis, DJ TI Multigrid approaches to non-linear diffusion problems on unstructured meshes SO NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS LA English DT Article; Proceedings Paper CT Workshop on Solution Methods for Large-Scale Non-Linear Problems CY JUL, 2000 CL PLEASANTON, CALIFORNIA SP Inst Terascale Simulat, Lawrence Livermore Natl Lab, Ctr Appl Sci Comp DE non-linear; unstructured; multigrid ID NONEQUILIBRIUM RADIATION DIFFUSION AB The efficiency of three multigrid methods for solving highly non-linear diffusion problems on two-dimensional unstructured meshes is examined. The three multigrid methods differ mainly in the manner in which the non-linearities of the governing equations are handled. These comprise a non-linear full approximation storage (FAS) multi-rid method which is used to solve the non-linear equations directly, a linear multigrid method which is used to solve the linear system arising from a Newton linearization of the non-linear system, and a hybrid scheme which is based on a non-linear FAS multigrid scheme, but employs a linear solver on each level as a smoother. Results indicate that, ill the asymptotic convergence region, all methods are equally effective at converging the lion-linear residual in a given number of multigrid cycles, but that the linear solver is more efficient in cpu time due to the lower cost of linear versus non-linear grid sweeps. Copyright (C) 2001 John Wiley & Sons, Ltd. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Mavriplis, DJ (reprint author), NASA, Langley Res Ctr, ICASE, MS 132C, Hampton, VA 23681 USA. NR 10 TC 15 Z9 16 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 1070-5325 J9 NUMER LINEAR ALGEBR JI Numer. Linear Algebr. Appl. PD DEC PY 2001 VL 8 IS 8 BP 499 EP 512 DI 10.1002/nla.262 PG 14 WC Mathematics, Applied; Mathematics SC Mathematics GA 494KP UT WOS:000172281700002 ER PT J AU Alexandrov, NM Lewis, RM AF Alexandrov, Natalia M. Lewis, Robert Michael TI An Overview of First-Order Model Management for Engineering Optimization SO OPTIMIZATION AND ENGINEERING LA English DT Article DE approximation concepts; approximation management; model management; nonlinear programming; optimal design; surrogate optimization AB First-order approximation/model management optimization (AMMO) is a rigorous methodology for solving high-fidelity optimization problems with minimal expense in high-fidelity function and derivative evaluation. AMMO is a general approach that is applicable to any derivative based optimization algorithm and any combination of high-fidelity and low-fidelity models. This paper gives an overview of the principles that underlie AMMO and puts the method in perspective with other similarly motivated methods. AMMO is first illustrated by an example of a scheme for solving bound-constrained optimization problems. The principles can be easily extrapolated to other optimization algorithms. The applicability to general models is demonstrated on two recent computational studies of aerodynamic optimization with AMMO. One study considers variable-resolution models, where the high-fidelity model is provided by solutions on a fine mesh, while the corresponding low-fidelity model is computed by solving the same differential equations on a coarser mesh. The second study uses variable-fidelity physics models, with the high-fidelity model provided by the Navier-Stokes equations and the low-fidelity model-by the Euler equations. Both studies show promising savings in terms of high-fidelity function and derivative evaluations. The overview serves to introduce the reader to the general concept of AMMO and to illustrate the basic principles with current computational results. C1 [Lewis, Robert Michael] Coll William & Mary, Williamsburg, VA 23187 USA. RP Lewis, RM (reprint author), NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. EM n.alexandrov@larc.nasa.gov; buckaroo@math.wm.edu NR 29 TC 95 Z9 95 U1 0 U2 9 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 1389-4420 J9 OPTIM ENG JI Optim. Eng. PD DEC PY 2001 VL 2 IS 4 SI SI BP 413 EP 430 DI 10.1023/A:1016042505922 PG 18 WC Engineering, Multidisciplinary; Operations Research & Management Science; Mathematics, Interdisciplinary Applications SC Engineering; Operations Research & Management Science; Mathematics GA V19TW UT WOS:000208095700005 ER PT J AU Stolarski, RS AF Stolarski, RS TI History of the study of atmospheric ozone SO OZONE-SCIENCE & ENGINEERING LA English DT Article DE ozone; atmospheric ozone; stratospheric ozone; ozone destruction; ozone layer ID ANTARCTIC OZONE; STRATOSPHERE; CHLORINE; DESTRUCTION; SINK AB Ozone is a substance that touches on our modem society in many ways. Ozone is used in industrial processes and as a disinfectant. Ozone is a strong oxidizing agent that is present in photochemical smog. Ozone in the stratosphere screens the surface of the earth from biologically damaging ultraviolet radiation. All of these uses emerge from our basic understanding of ozone that began with the recognition by Schonbein in 1840 that ozone was a unique substance produced in a variety of processes. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Stolarski, RS (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Stolarski, Richard/B-8499-2013 OI Stolarski, Richard/0000-0001-8722-4012 NR 36 TC 3 Z9 3 U1 5 U2 8 PU LEWIS PUBLISHERS PI BOCA RATON PA 2000 CORPORATE BLVD, NW, BOCA RATON, FL 33431 USA SN 0191-9512 J9 OZONE-SCI ENG JI Ozone-Sci. Eng. PD DEC PY 2001 VL 23 IS 6 BP 421 EP 428 DI 10.1080/01919510108962025 PG 8 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA 509QV UT WOS:000173161900001 ER PT J AU Llorente, IM Prieto-Matias, M Diskin, B AF Llorente, IM Prieto-Matias, M Diskin, B TI A parallel multigrid solver for 3D convection and convection-diffusion problems SO PARALLEL COMPUTING LA English DT Article DE robust multigrid; convection-dominated problems; parallel multigrid ID SMOOTHERS; EQUATIONS; SYSTEMS AB Multigrid algorithms are known to be highly efficient in solving systems of elliptic equations. However, standard multigrid algorithms fail to achieve optimal grid-independent convergence rates in solving non-elliptic problems. In many practical cases, the non-elliptic part of a problem is represented by the convection operator. Downstream marching, when it is viable, is the simplest and most efficient way to solve this operator. However, in a parallel setting, the sequential nature of marching degrades the efficiency of the algorithm. The aim of this paper is to present, evaluate and analyze an alternative highly parallel multigrid method for 3D convection-dominated problems. This method employs semicoarsening, a four-color plane-implicit smoother, and discretization rules allowing the same cross-characteristic interactions on all the grids involved to be maintained. The load imbalance below the critical level is the main source of inefficiency in its parallel implementation. After comparing several strategies to relieve the load imbalance, a hybrid smoother that degrades the convergence properties of the method but improves its granularity has been found to be the best choice. The numerical and parallel properties of the multigrid algorithm with the four-color and hybrid smoothers are studied on SGI Origin 2000 and Cray T3E systems. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Complutense Madrid, Fac CC Fis, Dept Arquitectura Computadores & Automatica, Madrid 28040, Spain. NASA Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. RP Llorente, IM (reprint author), Univ Complutense Madrid, Fac CC Fis, Dept Arquitectura Computadores & Automatica, Madrid 28040, Spain. RI Martin Llorente, Ignacio/B-2093-2009; Prieto-Matias, Manuel/K-8325-2012 OI Martin Llorente, Ignacio/0000-0001-6230-8180; Prieto-Matias, Manuel/0000-0003-0687-3737 NR 28 TC 7 Z9 7 U1 1 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-8191 J9 PARALLEL COMPUT JI Parallel Comput. PD DEC 1 PY 2001 VL 27 IS 13 BP 1715 EP 1741 DI 10.1016/S0167-8191(01)00115-6 PG 27 WC Computer Science, Theory & Methods SC Computer Science GA 472LE UT WOS:000170984900004 ER PT J AU Patel, UD Della Torre, E AF Patel, UD Della Torre, E TI Fast computation of the inverse CMH model SO PHYSICA B LA English DT Article; Proceedings Paper CT 3rd International Symposium on Hysteresis and Micromagnetics Modeling CY MAY 21-23, 2001 CL UNIV GEORGE WASHINGTON, ASHBURN, VIRGINIA HO UNIV GEORGE WASHINGTON DE magnetic hysteresis; hysteresis modeling; inverse problem; Preisach model AB A fast computational method based on differential equation approach for inverse Della Torre, Oti, Kadar (DOK) model has been extended for the inverse Complete Moving Hysteresis (CMH) model. A cobweb technique for calculating the inverse CMH model is also presented. The two techniques differ from the point of view of flexibility, accuracy, and computation time. Simulation results of the inverse Computation for both methods are presented. Published by Elsevier Science B.V. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. George Washington Univ, Washington, DC 20052 USA. RP Patel, UD (reprint author), NASA, Goddard Space Flight Ctr, Mailstop 564-0 Bldg 11,Rm EL219,Code 564, Greenbelt, MD 20771 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4526 J9 PHYSICA B JI Physica B PD DEC PY 2001 VL 306 IS 1-4 BP 178 EP 184 DI 10.1016/S0921-4526(01)01000-6 PG 7 WC Physics, Condensed Matter SC Physics GA 501LC UT WOS:000172685300034 ER PT J AU Quijada, MA Simpson, JR Vasiliu-Doloc, L Lynn, JW Drew, HD Mukovskii, YM Karabashev, SG AF Quijada, MA Simpson, JR Vasiliu-Doloc, L Lynn, JW Drew, HD Mukovskii, YM Karabashev, SG TI Temperature dependence of low-lying electronic excitations of LaMnO3 SO PHYSICAL REVIEW B LA English DT Article ID COLOSSAL-MAGNETORESISTANCE; OPTICAL-CONDUCTIVITY; DOUBLE EXCHANGE; LA1-XSRXMNO3; SPECTRA; POLARON; LA1-XCAXMNO3; RESISTIVITY; FILMS AB We report on the optical properties of undoped single crystal LaMnO3, the parent compound of the colossal magnetoresistive manganites. Near-normal-incidence-reflectance measurements are reported in the frequency range of 20-50 000 cm(-1) and in the temperature range 10-300 K. The optical conductivity sigma (1)(omega) is derived by performing a Kramers-Kronig analysis of the reflectance data. The far-infrared spectrum of sigma (1)(omega) displays the infrared active optical phonons. While several of the phonons soften as the temperature is raised, no anomalies in the width or frequency of the phonons are observed at the Neel temperature of the sample (T(N)similar to 139 K). The high-frequency sigma (1)(omega) is characterized by the onset of absorption near 1.5 eV, apeak at 2 eV, and a second larger peak at 4 eV. The 2-eV feature has been identified as optical transitions across the Jahn-Teller split e(g) levels. The spectral weight of this feature increases in the low-temperature state. This implies a transfer of spectral weight from the UV to the visible region associated with the paramagnetic to antiferromagnetic state. We discuss the results in terms of the double-exchange processes that affect the optical processes in this magnetic material. C1 Univ Maryland, Dept Phys, Mat Res Lab, College Pk, MD 20742 USA. Natl Inst Stand & Technol, Ctr Neutron Res, Gaithersburg, MD 20899 USA. Moscow Power Engn Inst, Moscow, Russia. RP Quijada, MA (reprint author), NASA, GSFC, Code 551, Greenbelt, MD 20740 USA. EM manuel.quijada@gsfc.nasa.gov NR 26 TC 29 Z9 29 U1 0 U2 7 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 EI 1550-235X J9 PHYS REV B JI Phys. Rev. B PD DEC 1 PY 2001 VL 64 IS 22 AR 224426 DI 10.1103/PhysRevB.64.224426 PG 7 WC Physics, Condensed Matter SC Physics GA 502FP UT WOS:000172733300069 ER PT J AU Cruden, BA AF Cruden, BA TI On the proposed second law paradox in a nonzero floating potential SO PHYSICS OF PLASMAS LA English DT Article ID 2ND LAW AB A second law paradox was previously proposed for a plasma contained within an infinite blackbody. The proposed second law paradox was dependent on the plasma having a nonzero floating potential [D. P. Sheehan and J. D. Means, Phys. Plasmas 5, 2469 (1998)]. This work demonstrates that a nonzero floating potential is indicative of some energy contained within the plasma that can be withdrawn from the plasma without violation of the second law. Furthermore, it is shown from the probe theory that the plasma in this hypothetical configuration must have a floating potential of zero at steady state. C1 NASA, Ames Res Ctr, Plasma Res Lab, Eloret Corp, Moffett Field, CA 94035 USA. RP Cruden, BA (reprint author), NASA, Ames Res Ctr, Plasma Res Lab, Eloret Corp, Moffett Field, CA 94035 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1070-664X J9 PHYS PLASMAS JI Phys. Plasmas PD DEC PY 2001 VL 8 IS 12 BP 5323 EP 5326 DI 10.1063/1.1415748 PG 4 WC Physics, Fluids & Plasmas SC Physics GA 494YM UT WOS:000172313500032 ER PT J AU Dozier, J Asrar, G AF Dozier, J Asrar, G TI John Edward 'Jack' Estes - Obituary SO PHYSICS TODAY LA English DT Biographical-Item C1 Univ Calif Santa Barbara, Santa Barbara, CA 93106 USA. NASA Headquarters, Washington, DC USA. RP Dozier, J (reprint author), Univ Calif Santa Barbara, Santa Barbara, CA 93106 USA. RI Dozier, Jeff/B-7364-2009 OI Dozier, Jeff/0000-0001-8542-431X NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD DEC PY 2001 VL 54 IS 12 BP 75 EP 75 DI 10.1063/1.1445565 PG 1 WC Physics, Multidisciplinary SC Physics GA 497MD UT WOS:000172458700017 ER PT J AU Solomon, SC McNutt, RL Gold, RE Acuna, MH Baker, DN Boynton, WV Chapman, CR Cheng, AF Gloeckler, G Head, JW Krimigis, SM McClintock, WE Murchie, SL Peale, SJ Phillips, RJ Robinson, MS Slavin, JA Smith, DE Strom, RG Trombka, JI Zuber, MT AF Solomon, SC McNutt, RL Gold, RE Acuna, MH Baker, DN Boynton, WV Chapman, CR Cheng, AF Gloeckler, G Head, JW Krimigis, SM McClintock, WE Murchie, SL Peale, SJ Phillips, RJ Robinson, MS Slavin, JA Smith, DE Strom, RG Trombka, JI Zuber, MT TI The MESSENGER mission to Mercury: scientific objectives and implementation SO PLANETARY AND SPACE SCIENCE LA English DT Review ID RADIO OCCULTATION MEASUREMENTS; GAMMA-RAY SPECTROSCOPY; MAGNETIC-FIELD; SILICATE FRACTIONATION; ENERGETIC PARTICLES; INTERNAL STRUCTURE; POLAR ANOMALIES; IMPACT CRATERS; X-RAY; ATMOSPHERE AB Mercury holds answers to several critical questions regarding the formation and evolution of the terrestrial planets. These questions include the origin of Mercury's anomalously high ratio of metal to silicate and its implications for planetary accretion processes, the nature of Mercury's geological evolution and interior cooling history, the mechanism of global magnetic field generation, the state of Mercury's core, and the processes controlling volatile species in Mercury's polar deposits, exosphere, and magnetosphere The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission has been designed to fly by and orbit Mercury to address all of these key questions. After launch by a Delta 2925H-9.5, two flybys of Venus, and two flybys of Mercury, orbit insertion is accomplished at the third Mercury encounter. The instrument payload includes a dual imaging system for wide and narrow fields-of-view, monochrome and color imaging, and stereo; X-ray and combined gamma-ray and neutron spectrometers for surface chemical mapping; a, magnetometer; a laser altimeter; a combined ultraviolet-visible and visible-near-infrared spectrometer to survey both exospheric species and surface mineralogy; and an energetic particle and plasma spectrometer to sample charged species in the magnetosphere. During the flybys of Mercury, regions unexplored by Mariner 10 will be seen for the first time, and new data will be gathered on Mercury's exosphere, magnetosphere, and surface composition. During the orbital phase of the mission, one Earth year in duration, MESSENGER will complete global mapping and the detailed characterization of the exosphere, magnetosphere, surface, and interior. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. SW Res Inst, Boulder, CO 80302 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA. Northwestern Univ, Dept Geol Sci, Evanston, IL 60208 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. RP Solomon, SC (reprint author), Carnegie Inst Washington, Dept Terr Magnetism, 5241 Broad Branch Rd NW, Washington, DC 20015 USA. RI Slavin, James/H-3170-2012; McNutt, Ralph/E-8006-2010; Murchie, Scott/E-8030-2015 OI Slavin, James/0000-0002-9206-724X; McNutt, Ralph/0000-0002-4722-9166; Murchie, Scott/0000-0002-1616-8751 NR 114 TC 229 Z9 229 U1 2 U2 17 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD DEC PY 2001 VL 49 IS 14-15 BP 1445 EP 1465 DI 10.1016/S0032-0633(01)00085-X PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 495VN UT WOS:000172361200005 ER PT J AU Gold, RE Solomon, SC McNutt, RL Santo, AG Abshire, JB Acuna, MH Afzal, RS Anderson, BJ Andrews, GB Bedini, PD Cain, J Cheng, AF Evans, LG Feldman, WC Follas, RB Gloeckler, G Goldsten, JO Hawkins, SE Izenberg, NR Jaskulek, SE Ketchum, EA Lankton, MR Lohr, DA Mauk, BH McClintock, WE Murchie, SL Schlemm, CE Smith, DE Starr, RD Zurbuchen, TH AF Gold, RE Solomon, SC McNutt, RL Santo, AG Abshire, JB Acuna, MH Afzal, RS Anderson, BJ Andrews, GB Bedini, PD Cain, J Cheng, AF Evans, LG Feldman, WC Follas, RB Gloeckler, G Goldsten, JO Hawkins, SE Izenberg, NR Jaskulek, SE Ketchum, EA Lankton, MR Lohr, DA Mauk, BH McClintock, WE Murchie, SL Schlemm, CE Smith, DE Starr, RD Zurbuchen, TH TI The MESSENGER mission to Mercury: scientific payload SO PLANETARY AND SPACE SCIENCE LA English DT Article ID GAMMA-RAY SPECTROMETER; ENERGETIC PARTICLES; SPACECRAFT; INSTRUMENT AB The MErcury, Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission will send the first spacecraft to orbit the planet Mercury. A miniaturized set of seven instruments, along with the spacecraft telecommunications system, provide the means of achieving the scientific objectives that motivate the mission. The payload includes a combined wide- and narrow-angle imaging system; gamma -ray, neutron, and X-ray spectrometers for remote geochemical sensing; a vector magnetometer; a laser altimeter; a combined ultraviolet-visible and visible-infrared spectrometer to detect atmospheric species and map mineralogical absorption features; and an energetic particle and plasma spectrometer to characterize ionized species in the magnetosphere. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. RP Gold, RE (reprint author), Johns Hopkins Univ, Appl Phys Lab, Johns Hopkins Rd, Laurel, MD 20723 USA. RI Anderson, Brian/I-8615-2012; Abshire, James/I-2800-2013; McNutt, Ralph/E-8006-2010; Murchie, Scott/E-8030-2015; Izenberg, Noam/F-3952-2015; Mauk, Barry/E-8420-2017 OI McNutt, Ralph/0000-0002-4722-9166; Murchie, Scott/0000-0002-1616-8751; Izenberg, Noam/0000-0003-1629-6478; Mauk, Barry/0000-0001-9789-3797 NR 21 TC 86 Z9 87 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD DEC PY 2001 VL 49 IS 14-15 BP 1467 EP 1479 DI 10.1016/S0032-0633(01)00086-1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 495VN UT WOS:000172361200006 ER PT J AU Santo, AG Gold, RE McNutt, RL Solomon, SC Ercol, CJ Farquhar, RW Hartka, TJ Jenkins, JE McAdams, JV Mosher, LE Persons, DF Artis, DA Bokulic, RS Conde, RF Dakermanji, G Goss, ME Haley, DR Heeres, KJ Maurer, RH Moore, RC Rodberg, EH Stern, TG Wiley, SR Williams, BG Yen, CWL Peterson, MR AF Santo, AG Gold, RE McNutt, RL Solomon, SC Ercol, CJ Farquhar, RW Hartka, TJ Jenkins, JE McAdams, JV Mosher, LE Persons, DF Artis, DA Bokulic, RS Conde, RF Dakermanji, G Goss, ME Haley, DR Heeres, KJ Maurer, RH Moore, RC Rodberg, EH Stern, TG Wiley, SR Williams, BG Yen, CWL Peterson, MR TI The MESSENGER mission to Mercury: spacecraft and mission design SO PLANETARY AND SPACE SCIENCE LA English DT Article ID SYSTEM AB A Mercury orbiter mission is challenging from thermal and mass perspectives. The Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) mission overcomes these challenges while avoiding esoteric technologies by using an innovative approach with commonly available materials, minimal moving parts, and maximum heritage. This approach yields a spacecraft with good margins in all categories and low technical risk. The key concepts are a ceramic-cloth sunshade, an integrated lightweight structure and highperformance propulsion system, and a solar array incorporating optical solar reflectors (OSRs). The sunshade maintains the spacecraft at room temperature. The integrated structure and propulsion system provides ample mass margin. The solar array with OSRs, which has already undergone significant testing, provides thermal margin even if the panels are inadvertently pointed directly at the Sun at 0.3 AU. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. Composite Opt Inc, San Diego, CA 92121 USA. GenCorp Aerojet, Sacramento, CA 95813 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Santo, AG (reprint author), Johns Hopkins Univ, Appl Phys Lab, Johns Hopkins Rd, Laurel, MD 20723 USA. RI McNutt, Ralph/E-8006-2010 OI McNutt, Ralph/0000-0002-4722-9166 NR 19 TC 64 Z9 64 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD DEC PY 2001 VL 49 IS 14-15 BP 1481 EP 1500 DI 10.1016/S0032-0633(01)00087-3 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 495VN UT WOS:000172361200007 ER PT J AU Burlaga, LF AF Burlaga, LF TI Magnetic fields and plasmas in the inner heliosphere: Helios results SO PLANETARY AND SPACE SCIENCE LA English DT Article ID SOLAR-WIND; AU; STREAM AB The magnetic field of Mercury and the structure and dynamics of Mercury's magnetosphere, which will be studied by the spacecraft orbiting Mercury, are strongly influenced by the interaction of the solar wind with Mercury. In order to understand the internal magnetic field, it will be necessary to correct the observations of the external field for the distortions produced by the solar wind. Understanding of the solar wind interaction with Mercury is essential for understanding the structure and dynamics of the magnetosphere and phenomena such as magnetic storms. Helios 1 and 2 made a number of passes in the region traversed by the orbit of Mercury, and each pass provided a sample of the solar wind environment of Mercury. This paper reviews the plasma and magnetic field observations from Helios that provide a general basis for interpreting the observations of Mercury that will be made by orbiting spacecraft. The variables that, govern the structure and dynamics of the magnetospheres of Mercury and Earth are approximately 5-10 times larger at Mercury than at Earth. Thus, the solar wind interaction with Mercury will be much stronger than the interaction with Earth. Moreover, the solar wind at Mercury is probably more variable than that at Earth. There is a clear need for measurements of the solar wind during the approach of spacecraft to Mercury and while they are in orbit around Mercury. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Burlaga, LF (reprint author), NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Code 692, Greenbelt, MD 20771 USA. NR 31 TC 26 Z9 28 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD DEC PY 2001 VL 49 IS 14-15 BP 1619 EP 1627 DI 10.1016/S0032-0633(01)00098-8 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 495VN UT WOS:000172361200018 ER PT J AU Echternach, P Williams, CP Dultz, SC Delsing, P Braunstein, S Dowling, JP AF Echternach, P. Williams, C. P. Dultz, S. C. Delsing, P. Braunstein, S. Dowling, J. P. TI UNIVERSAL QUANTUM GATES FOR SINGLE COOPER PAIR BOX BASED QUANTUM COMPUTING SO QUANTUM INFORMATION & COMPUTATION LA English DT Article C1 [Echternach, P.; Dultz, S. C.] CALTECH, Jet Prop Lab, Microdevices Lab, Pasadena, CA 91125 USA. [Williams, C. P.; Dowling, J. P.] CALTECH, Jet Prop Lab, Quantum Comp Grp, Pasadena, CA USA. [Delsing, P.] Chalmers, S-41296 Gothenburg, Sweden. [Braunstein, S.] Univ Wales, Bangor, Gwynedd, Wales. RP Echternach, P (reprint author), CALTECH, Jet Prop Lab, Microdevices Lab, Pasadena, CA 91125 USA. FU National Aeronautics and Space Administration; National Security Agency; Advanced Research and Development Activity FX The research described in this publication has been carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This work was partially funded by the National Security Agency and the Advanced Research and Development Activity. NR 18 TC 12 Z9 12 U1 0 U2 0 PU RINTON PRESS, INC PI PARAMUS PA 565 EDMUND TERRACE, PARAMUS, NJ 07652 USA SN 1533-7146 J9 QUANTUM INF COMPUT JI Quantum Inform. Comput. PD DEC PY 2001 VL 1 SI SI BP 143 EP 150 PG 8 WC Computer Science, Theory & Methods; Physics, Particles & Fields; Physics, Mathematical SC Computer Science; Physics GA V31RX UT WOS:000208901800016 ER PT J AU George, K Durante, M Wu, H Willingham, V Badhwar, G Cucinotta, FA AF George, K Durante, M Wu, H Willingham, V Badhwar, G Cucinotta, FA TI Chromosome aberrations in the blood lymphocytes of astronauts after space flight SO RADIATION RESEARCH LA English DT Article ID IN-SITU HYBRIDIZATION; BIOLOGICAL DOSIMETRY; ROGUE CELLS; RADIATION; DAMAGE; FREQUENCY; ASSOCIATION; PARTICLES; EXPOSURE; REPAIR AB Cytogenetic analysis of the lymphocytes of astronauts provides a direct measurement of space radiation damage in vivo, which takes into account individual radiosensitivity and considers the influence of microgravity and other stress conditions. Chromosome exchanges were measured in the blood lymphocytes of eight crew members after their respective space missions, using fluorescence in situ hybridization (FISH) with chromosome painting probes. Significant increases in aberrations were observed after the long-duration missions. The in vivo dose was derived from the frequencies of translocations and total exchanges using calibration curves determined before flight, and the RBE was estimated by comparison with individually measured physical absorbed doses. The values for average RBE were compared to the average quality factor (Q) from direct measurements of the lineal energy spectra using a tissue-equivalent proportional counter (TEPC) and radiation transport codes. The ratio of aberrations identified as complex was slightly higher after flight, which is thought to be an indication of exposure to high-LET radiation. To determine whether the frequency of complex aberrations measured in metaphase spreads after exposure to high-LET radiation was influenced by a cell cycle delay, chromosome damage was analyzed in prematurely condensed chromosome samples collected from two crew members before and after a short-duration mission. The frequency of complex exchanges after flight was higher in prematurely condensed chromosomes than in metaphase cells for one crew member. (C) 2001 by Radiation Research Society. C1 Wyle Labs, Houston, TX 77058 USA. NASA, Kelsey Seybold Clin, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Naples Federico II, Dept Phys, I-80126 Naples, Italy. RP George, K (reprint author), Wyle Labs, 1290 Hercules Dr,Suite 120, Houston, TX 77058 USA. RI Durante, Marco/K-1315-2014; OI Durante, Marco/0000-0002-4615-553X NR 35 TC 70 Z9 73 U1 0 U2 2 PU RADIATION RESEARCH SOC PI OAK BROOK PA 820 JORIE BOULEVARD, OAK BROOK, IL 60523 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD DEC PY 2001 VL 156 IS 6 BP 731 EP 738 DI 10.1667/0033-7587(2001)156[0731:CAITBL]2.0.CO;2 PG 8 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 507JW UT WOS:000173025000006 PM 11741497 ER PT J AU Hall-Atkinson, C Smith, LC AF Hall-Atkinson, C Smith, LC TI Delineation of delta ecozones using interferometric SAR phase coherence Mackenzie River Delta, NWT, Canada SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SYNTHETIC-APERTURE-RADAR; FOREST; DECORRELATION; VEGETATION; FLOODPLAIN; WETLANDS; IMAGERY; AREA AB Interferometric processing of six C-band synthetic aperture radar (SAR) image pairs for the Mackenzie River Delta shows that phase coherence is more effective than radar backscatter for differentiating willow-alder, spruce, ice, and open water. Similar radar backscattering from vegetation and wind-roughened water surfaces can make such distinctions difficult in SAR backscatter images. In contrast, coherence is preserved over surfaces with rigid scattering elements, such as leafless woody alder, but is lost over temporally unstable surfaces such as open water. We find that willow-alder display highest coherence followed by spruce, frozen lakes and channels, and open water, respectively. This general hierarchy is preserved even when overall image coherence is decreased by increasing temporal and spatial baselines. Evaluation of spatial, thermal noise and temporal components of total observed coherence indicates that temporal decorrelation is a primary control. Short temporal baselines, such as those obtained during the European Remote Sensing Satellite (ERS) 1-day tandem missions, are therefore optimal for obtaining maximum differentiation of surface classes. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Univ Calif Los Angeles, Dept Geog, Los Angeles, CA 90095 USA. RP Hall-Atkinson, C (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 171264, Pasadena, CA 91109 USA. RI Smith, Laurence/E-7785-2012 OI Smith, Laurence/0000-0001-6866-5904 NR 38 TC 9 Z9 10 U1 1 U2 5 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD DEC PY 2001 VL 78 IS 3 BP 229 EP 238 DI 10.1016/S0034-4257(01)00221-8 PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 500NM UT WOS:000172633700002 ER PT J AU Miura, T Huete, AR Yoshioka, H Holben, BN AF Miura, T Huete, AR Yoshioka, H Holben, BN TI An error and sensitivity analysis of atmospheric resistant vegetation indices derived from dark target-based atmospheric correction SO REMOTE SENSING OF ENVIRONMENT LA English DT Article DE vegetation indices; atmospheric correction; dark target approach; error analysis; sensitivity analysis ID AVHRR DATA; EOS-MODIS; NEAR-IR; AEROSOL; SOIL; REFLECTANCE; INDEX; LAND; MANAGEMENT; ALGORITHM AB An error and sensitivity analysis was conducted to investigate the capabilities of the atmospheric resistant vegetation indices (VIs) for minimizing "residual aerosol" effects. The residual aerosol effects result from the assumptions and characteristics of the dark target (DT) approach used to estimate aerosol optical properties in the atmospheric correction scheme (referred to as the dark target-based atmospheric correction, DTAC). The performances of two atmospheric resistant VIs, the atmospherically resistant vegetation index (ARVI) and enhanced vegetation index (EVI), were evaluated and compared with the normalized difference vegetation index (NDVI) and soil adjusted vegetation index (SAVI). The atmospheric resistant VIs successfully minimized the residual aerosol effects, resulting in a 60%, reduction of the errors from the NDVI and SAVI when a proper aerosol model was used for the estimation and correction of aerosol effects. The reductions were greater for thicker aerosol atmosphere (larger aerosol optical thickness, AOT). The atmospheric resistant VIs, however, resulted in having larger bias errors than the NDVI and SAVI when an improper aerosol model was used. The application of atmospheric resistant VIs to the DTAC-derived surface reflectances is exactly what is being carried out by the Moderate Resolution Imaging Spectroradiometer (MODIS) VI algorithm. These results raise several issues for the effective, operational use of the DTAC algorithm and atmospheric resistant VIs, which are addressed in this paper. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Univ Arizona, Dept Soil Water & Environm Sci, Tucson, AZ 85721 USA. Aichi Prefectural Univ, Dept Appl Informat Sci & Technol, Aichi 4801198, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Miura, T (reprint author), Univ Arizona, Dept Soil Water & Environm Sci, Tucson, AZ 85721 USA. RI Miura, Tomoaki/B-5805-2008; Huete, Alfredo/C-1294-2008 OI Huete, Alfredo/0000-0003-2809-2376 NR 35 TC 45 Z9 51 U1 0 U2 13 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD DEC PY 2001 VL 78 IS 3 BP 284 EP 298 DI 10.1016/S0034-4257(01)00223-1 PG 15 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 500NM UT WOS:000172633700007 ER PT J AU Wang, YJ Tian, YH Zhang, Y El-Saleous, N Knyazikhin, Y Vermote, E Myneni, RB AF Wang, YJ Tian, YH Zhang, Y El-Saleous, N Knyazikhin, Y Vermote, E Myneni, RB TI Investigation of product accuracy as a function of input and model uncertainties - Case study with SeaWiFS and MODIS LAI/FPAR algorithm SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID LEAF-AREA INDEX; PHOTOSYNTHETICALLY ACTIVE RADIATION; FPAR ALGORITHM; NDVI; LAND; REFLECTANCE; ATMOSPHERE; FRACTION; FORESTS; LAI AB The derivation of vegetation leaf area index (LAI) and the fraction of photosynthetically active radiation (FPAR) absorbed by vegetation globally from the Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) multispectral surface reflectances using the algorithm developed for the moderate resolution imaging spectroradiometer (MODIS) instrument is discussed here, with special emphasis on the quality of the retrieved fields. Uncertainties in the land surface reflectance and model used in the algorithm determine the quality of the retrieved LAI/FPAR fields. The in-orbit radiances measured by space-borne sensors require corrections for calibration and atmospheric effects, and this introduces uncertainty in the surface reflectance products. The model uncertainty characterizes the accuracy of a vegetation radiation interaction model to approximate the observed variability in surface reflectances. When the amount of spectral information input to the retrieval technique is increased, not only does this increase the overall information content but also decreases the summary accuracy in the data. The former enhances quality of the retrievals, while the latter suppresses it. The quality of the retrievals can be influenced by the use of uncertainty information in the retrieval technique. We introduce a stabilized uncertainty, which is basic information to the retrieval technique required to establish its convergence; that is, the more the measured information and the more accurate this information is, the more reliable and accurate the algorithm output will be. The quality of retrieval is a function of the stabilized uncertainty whose accurate specification is critical for deriving biophysical surface parameters of the highest quality possible using multispectral land surface data. The global LAI and FPAR maps derived from SeaWiFS multispectral surface reflectances and uncertainty information, as well as an analysis of these products is presented here. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Boston Univ, Dept Geog, Boston, MA 02215 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wang, YJ (reprint author), Boston Univ, Dept Geog, 675 Commonwealth Ave, Boston, MA 02215 USA. RI Vermote, Eric/K-3733-2012; Myneni, Ranga/F-5129-2012 NR 35 TC 49 Z9 56 U1 3 U2 12 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD DEC PY 2001 VL 78 IS 3 BP 299 EP 313 DI 10.1016/S0034-4257(01)00225-5 PG 15 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 500NM UT WOS:000172633700008 ER PT J AU Johnson, LF AF Johnson, LF TI Nitrogen influence on fresh-leaf NIR spectra SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID RADIATIVE-TRANSFER MODEL; CANOPY CHEMISTRY; FOREST CANOPY; BIOCHEMISTRY; AVIRIS AB Simulations and measurements were used derive information on the form and strength of the nitrogen (N) "signal" in near-infrared (NIR) spectra of fresh leaves. Simulations across multiple species indicated that in total, protein absorption decreased NIR reflectance by up to 1.8% absolute and transmittance by up to 3.7% absolute, all other inputs held equal. Associated changes in spectral slope were generally of +/-0.02% nm(-1) absolute. Spectral effects were about an order of magnitude more subtle fur a smaller, though potentially ecologically significant, change in N concentration of 0.5% absolute over measured. Nitrogen influence on spectral slope was fairly consistent across four empirical datasets as judged by wavelength dependence of N correlation, and there was reasonable agreement of observed and modeled slope perturbations with locations of known protein absorption features. Improved understanding of the form and strength of the N signal under differing conditions will support continued development of laboratory-based spectral measurement and analysis strategies for direct N estimation in individual fresh leaves. A pragmatic approach for canopy-level estimation by remote sensing, however, might additionally consider surrogate measures such as chlorophyll concentration or canopy biophysical properties. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Calif State Univ Monterey Bay, Seaside, CA 93955 USA. NASA, Ames Res Ctr 242 4, Ecosyst Sci & Technol Branch, Moffett Field, CA 94035 USA. RP Johnson, LF (reprint author), Calif State Univ Monterey Bay, Seaside, CA 93955 USA. NR 29 TC 29 Z9 32 U1 1 U2 8 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD DEC PY 2001 VL 78 IS 3 BP 314 EP 320 DI 10.1016/S0034-4257(01)00226-7 PG 7 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 500NM UT WOS:000172633700009 ER PT J AU Simpson, JJ Hufford, GL Pieri, D Berg, JS AF Simpson, JJ Hufford, GL Pieri, D Berg, JS TI Failures in detecting volcanic ash from a satellite-based technique - Response SO REMOTE SENSING OF ENVIRONMENT LA English DT Editorial Material ID ERUPTION; CLOUDS AB Prata et al. [Remote Sens. Environ. (2001)] state that our analysis [Remote Sens. Environ. 72 (2000) 191] "suffers from a fundamental flaw in its methodology and numerous errors in fact and interpretation." We assert that Prata et al. [Remote Sens. Environ. (2001)] are incorrect. Our original analysis, augmented herein, shows that from an aviation safety perspective, their T-4-T-5 volcanic ash detection algorithm does not meet the requirements of the aviation industry. For arbitrary satellite scenes, their algorithm: (1) underdetects airborne volcanic ash; (2) yields numerous false alarms; and (3) does not satisfy the 5 min warning imperative mandated by the aviation industry. Independent evidence and unique in situ validation data from the NASA DC-8 encounter with volcanic products from the recent Hekla eruption further support our original analysis and conclusions. Factors affecting the usefulness of their algorithm within the context of aviation safety include, but are not limited to, ambient atmospheric water vapor, ground and juvenile water in the magma as well as its chemical composition, cloud cover, atmospheric ice crystals, and the general applicability of the theoretical assumptions underlying their T-4-T-5 volcanic ash detection algorithm. The new analyses presented herein, as well as those of Simpson et al. [Remote Sens. Environ. 72 (2000) 191], show that new approaches are needed to address the complex problem of accurate and rapid detection of airborne volcanic ash. 2001 Elsevier Science Inc. All rights reserved. C1 Univ Calif San Diego, Scripps Inst Oceanog, Digital Image Anal Lab, La Jolla, CA 92093 USA. Natl Weather Serv, Anchorage, AK USA. Jet Prop Lab, Pasadena, CA USA. RP Simpson, JJ (reprint author), Univ Calif San Diego, Scripps Inst Oceanog, Digital Image Anal Lab, La Jolla, CA 92093 USA. NR 31 TC 19 Z9 19 U1 1 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD DEC PY 2001 VL 78 IS 3 BP 347 EP 357 DI 10.1016/S0034-4257(01)00230-9 PG 11 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 500NM UT WOS:000172633700013 ER PT J AU Steyert, DW Sirota, JM Mickelson, ME Reuter, DC AF Steyert, DW Sirota, JM Mickelson, ME Reuter, DC TI Two new long-pass cells for infrared and visible spectroscopy SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID LASER SPECTROSCOPY; ABSORPTION; H-2; SYSTEMS AB We describe two very long path absorption cells for sensitive laser absorption spectroscopy which are based on a design first described by Chernin and Barskaya [Appl. Opt. 30, 51 (1991)]. The cells distribute a nearly arbitrary number of spots across both dimensions of the field mirror in an efficient, compact array: confining up to 500 traversals in a 26 cm diam cooled cylindrical vacuum housing. The first cell, constructed at Denison University, is one of several multipass cells in the Laser Spectroscopy Laboratory used in the visible and near infrared (400-1100 nm). Optical paths of up to 1 km have been attained in this 3 m long cell at pressures from near vacuum to several atmospheres. The cell operates at temperatures down to 125 K. Conventional Pyrex optics are used. The second cell is part of a long path laboratory laser absorption spectrometer used in the thermal infrared: 350-2000 cm(-1) at Goddard Space Flight Center. Path lengths up to 476 m have been achieved at frequencies less than 500 cm(-1). Two unique features of the Goddard cell are the piezoelectric micrometers, which simplify considerably the controls for the optical alignment, and the diamond-turned spherical mirrors, which significantly reduce the cost and the complexity of cryogenic operation. In addition, we discuss criteria for determining the optimal pathlength of a given multipass cell for the measurement of weak spectral lines. (C) 2001 American Institute of Physics. C1 Univ Maryland, Joint Ctr Earth Syst Technol, Baltimore, MD 21250 USA. Denison Univ, Dept Phys & Astron, Granville, OH 43023 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Steyert, DW (reprint author), Univ Maryland, Joint Ctr Earth Syst Technol, Baltimore, MD 21250 USA. NR 25 TC 11 Z9 11 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD DEC PY 2001 VL 72 IS 12 BP 4337 EP 4343 DI 10.1063/1.1409565 PG 7 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 496GG UT WOS:000172387400002 ER PT J AU Storrie-Lombardi, MC Hug, WF McDonald, GD Tsapin, AI Nealson, KH AF Storrie-Lombardi, MC Hug, WF McDonald, GD Tsapin, AI Nealson, KH TI Hollow cathode ion lasers for deep ultraviolet Raman spectroscopy and fluorescence imaging SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID UV RESONANCE RAMAN; FILAMENTOUS VIRUS FD; EXCITATION PROFILES; DECAY CHARACTERISTICS; HYDROGEN-EXCHANGE; ESCHERICHIA-COLI; LIVE BACTERIA; STEADY-STATE; PRD1 VIRUS; SPECTRA AB This article describes the development of hollow cathode ion lasers and their use in constructing an ultraviolet micro-Raman spectrograph with native fluorescence imaging capability. Excitation at 224.3 nm is provided by a helium-silver hollow cathode metal ion laser and at 248.6 nm by a neon-copper hollow cathode metal ion laser. Refractive microscope objectives focus chopped continuous wave laser light on a sample and collect 180 degrees scattered photons. Imaging is accomplished by broadband visible illumination and by deep ultraviolet laser induced excitation of visible wavelength native fluorescence in untagged micro-organisms. This makes possible a detection strategy employing rapid imaging with laser excitation to locate regions of native fluorescence activity, followed by deep ultraviolet resonance Raman spectroscopy of the identified fluorescent sites. We have employed this probe for in situ detection of micro-organisms on mineral and soil substrates. We present here the deep ultraviolet resonance Raman spectra for the gram negative iron reducing bacterium Shewanella oneidensis obtained while the micro-organism remains in situ on the unpolished surface of the mineral calcite and in a Mars soil analog, JSC1. In the current configuration the in situ mineral surface limit of detection for fluorescence is one organism in 2x10(4) mum(2) field of view and of order 20-30 micro-organisms for Raman spectra. For the Mars soil sample analog fluorescent target selection gives an effective ultraviolet resonance Raman spectral detection limit of 6x10(4) cells/gm or similar to 60 ppb. (C) 2001 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Photon Syst Inc, Covina, CA 91722 USA. RP Storrie-Lombardi, MC (reprint author), CALTECH, Jet Prop Lab, MS 183-301-4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 69 TC 48 Z9 50 U1 3 U2 13 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD DEC PY 2001 VL 72 IS 12 BP 4452 EP 4459 DI 10.1063/1.1369627 PG 8 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 496GG UT WOS:000172387400023 ER PT J AU Hitt, DL Zakrzwski, CM Thomas, MA AF Hitt, DL Zakrzwski, CM Thomas, MA TI MEMS-based satellite micropropulsion via catalyzed hydrogen peroxide decomposition SO SMART MATERIALS & STRUCTURES LA English DT Article ID FLOWS AB Microelectromechanical systems (MEMS) techniques offer great potential in satisfying the mission requirements for the next generation of miniaturized spacecraft being designed by NASA and Department of Defense agencies. More commonly referred to as 'nanosats', these spacecraft feature masses in the range of 10-100 kg and therefore have unique propulsion requirements. The propulsion systems must be capable of providing extremely low levels of thrust and impulse while also satisfying stringent demands on size, mass, power consumption and cost. We begin with an overview of micropropulsion requirements and some current MEMS-based strategies being developed to meet these needs. The remainder of the paper focuses on the progress being made at NASA Goddard Space Flight Center toward the development of a prototype monopropellant MEMS thruster which uses the catalyzed chemical decomposition of high-concentration hydrogen peroxide as a propulsion mechanism. The products of decomposition are delivered to a microscale converging/diverging supersonic nozzle, which produces the thrust vector; the targeted thrust level is approximately 500 AN with a specific impulse of 140-180 s. Macroscale hydrogen peroxide thrusters have been used for satellite propulsion for decades; however, the implementation of traditional thruster designs on the MEMS scale has uncovered new challenges in fabrication, materials compatibility, and combustion and hydrodynamic modeling. A summary of the achievements of the project to date is given, as is a discussion of remaining challenges and future prospects. C1 Univ Vermont, Dept Mech Engn, Burlington, VT 05405 USA. NASA, Prop Branch, Guidance Navigat & Control Ctr, Goddard Space Flight Ctr, Greenbelt, MD USA. NR 29 TC 95 Z9 106 U1 1 U2 11 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0964-1726 J9 SMART MATER STRUCT JI Smart Mater. Struct. PD DEC PY 2001 VL 10 IS 6 BP 1163 EP 1175 DI 10.1088/0964-1726/10/6/305 PG 13 WC Instruments & Instrumentation; Materials Science, Multidisciplinary SC Instruments & Instrumentation; Materials Science GA 516LZ UT WOS:000173555900006 ER PT J AU Tung, S Witherspoon, SR Roe, LA Silano, A Maynard, DP Ferraro, N AF Tung, S Witherspoon, SR Roe, LA Silano, A Maynard, DP Ferraro, N TI A MEMS-based flexible sensor and actuator system for space inflatable structures SO SMART MATERIALS & STRUCTURES LA English DT Article ID ARTIFICIAL MUSCLES AB Inflatable and other membrane structures are expected to become increasingly important in space exploration due to their light weight and low cost. Unlike rigid structures, these structures are typically fabricated of flexible polymers and require internal pressurization to achieve structural integrity. Due to this, inflatable structures are vulnerable to the harsh space environment and catastrophic failure from structural vibration. A MEMS-based health monitoring and control system (HMCS) for space inflatables has been developed at the University of Arkansas. Fabricated mostly from polymeric materials, the HMCS is lightweight, flexible and can be attached directly to the external surface of an inflatable to provide health monitoring. Structure-wise, the HMCS is a three-dimensional multichip module with a sensor layer at the top, a common polyimide substrate in the middle and an actuator layer at the bottom. The sensor layer consists of an interconnected network of MEMS sensors for monitoring the environmental conditions around the inflatable and also the structural vibration of the inflatable. The actuator layer, fabricated from electroactive polymers, provides a two-dimensional shape control capability to the HMCS. When operated with strain and vibration sensors in the sensor layer, the polymer actuator can deform the surface contour of the inflatable to remove 'wrinkles' and dampen structural vibration. C1 Univ Arkansas, Dept Mech Engn, Fayetteville, AR 72701 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. NR 19 TC 53 Z9 53 U1 2 U2 12 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0964-1726 J9 SMART MATER STRUCT JI Smart Mater. Struct. PD DEC PY 2001 VL 10 IS 6 BP 1230 EP 1239 DI 10.1088/0964-1726/10/6/312 PG 10 WC Instruments & Instrumentation; Materials Science, Multidisciplinary SC Instruments & Instrumentation; Materials Science GA 516LZ UT WOS:000173555900013 ER PT J AU Share, GH Murphy, RJ Tylka, AJ Schwartz, RA Yoshimori, M Suga, K Nakayama, S Takeda, H AF Share, GH Murphy, RJ Tylka, AJ Schwartz, RA Yoshimori, M Suga, K Nakayama, S Takeda, H TI Gamma-ray line observations of the 2000 July 14 flare and SEP impact on the Earth SO SOLAR PHYSICS LA English DT Article ID SOLAR-FLARES; ENERGY; ABUNDANCES; PARTICLES; PROTONS; YOHKOH AB The HXS and GRS detectors on Yohkoh observed the 14 July 2000, X5.7 flare, beginning at similar to 10:20 UT, similar to 4 min before the peak in soft X-rays. The hard X-rays and gamma-rays peaked similar to 3 min later at similar to 10:27 UT. Solar gamma-ray emission lasted until similar to 10:40 UT. Impact of high-energy ions at the Sun is revealed by the gamma-ray lines from neutron capture, annihilation radiation and de-excitation that are visible above the bremsstrahlung continuum. From measurement of these lines we find that the flare-averaged spectrum of accelerated protons is consistent with a power law ge10 MeV with index 3.14+/-0.15 and flux 1.1x10(32) protons MeV-1 at 10 MeV. We estimate that there were similar to1.5x10(30) erg in accelerated ions if the power law extended without a break down to 1 MeV; this is about 1% of the energy in electrons > 20 keV from measurements of the hard X-rays. We find no evidence for spectral hardening in the hard X-rays that has been suggested as a predictor for the occurrence of solar energetic particle (SEP) events. This was the third largest proton event above 10 MeV since 1976. The GRS and HXS also observed gamma-ray lines and continuum produced by the impact of SEP on the Earth's atmosphere beginning about 13 UT on 14 July. These measurements show that the SEP spectrum softened considerably over the next 24 hours. We compare these measurements with proton measurements in space. C1 USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, LASP, Greenbelt, MD 20771 USA. Rikkyo Univ, Dept Phys, Toshima Ku, Tokyo 1718501, Japan. RP Share, GH (reprint author), USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. RI Tylka, Allan/G-9592-2014 NR 20 TC 11 Z9 11 U1 1 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD DEC PY 2001 VL 204 IS 1-2 BP 43 EP 55 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 524BU UT WOS:000173992700004 ER PT J AU Reiner, MJ Kaiser, ML Karlicky, M Jiricka, K Bougeret, JL AF Reiner, MJ Kaiser, ML Karlicky, M Jiricka, K Bougeret, JL TI Bastille Day event: A radio perspective SO SOLAR PHYSICS LA English DT Article ID CORONAL MASS EJECTION; SOLAR-WIND SPEED; INTERPLANETARY MEDIUM; LOW-FREQUENCIES; ACTIVE REGIONS; II BURSTS; SHOCKS; EMISSIONS; DENSITY; STORMS AB We describe the radio signatures that led up to and concluded the solar eruptive event of 14 July 2000 (Bastille Day Event). These radio signatures provide a means of remotely sensing the associated solar activity and transient phenomena. For many days prior to the Bastille Day Event kilometric Type III radio storm emissions were observed that were presumably associated with the active region NOAA 9077. These storm emissions continued until the X5.7 flare at similar to 10 UT on 14 July 2000 that characterized the Bastille Day Event, then ceased abruptly. The Bastille Day Event itself produced very intense, complex, long-duration Type III-like radio emissions, which appear to have been associated with electrons generated (accelerated) deep in the solar corona. The coronal mass ejection (CME) associated with the Bastille Day Event generated decametric to kilometric Type II radio emissions as the CME propagated through the solar corona and interplanetary medium. The frequency drift of these Type II radio emissions are related to the dynamics of the propagating CME and indicate that the CME experienced significant deceleration as it propagated from the high corona into the interplanetary medium. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. Acad Sci Czech Republ, Astron Inst, CZ-25165 Ondrejov, Czech Republic. Observ Paris, Meudon, France. RP Reiner, MJ (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RI Karlicky, Marian/G-9023-2014 NR 38 TC 21 Z9 22 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD DEC PY 2001 VL 204 IS 1-2 BP 123 EP 139 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 524BU UT WOS:000173992700008 ER PT J AU Smith, CW Ness, NF Burlaga, LF Skoug, RM McComas, DJ Zurbuchen, TH Gloeckler, G Haggerty, DK Gold, RE Desai, MI Mason, GM Mazur, JE Dwyer, JR Popecki, MA Mobius, E Cohen, CMS Leske, RA AF Smith, CW Ness, NF Burlaga, LF Skoug, RM McComas, DJ Zurbuchen, TH Gloeckler, G Haggerty, DK Gold, RE Desai, MI Mason, GM Mazur, JE Dwyer, JR Popecki, MA Mobius, E Cohen, CMS Leske, RA TI ACE observations of the Bastille Day 2000 interplanetary disturbances SO SOLAR PHYSICS LA English DT Article ID ADVANCED-COMPOSITION-EXPLORER; ENERGETIC PARTICLE EVENTS; CORONAL MASS EJECTIONS; SOLAR-WIND; ISOTOPE SPECTROMETER; ALPHA-MONITOR; ACCELERATION; ABUNDANCES; SPACECRAFT; EVOLUTION AB We present ACE observations for the six-day period encompassing the Bastille Day 2000 solar activity. A high level of transient activity at 1 AU, including ICME-driven shocks, magnetic clouds, shock-accelerated energetic particle populations, and solar energetic ions and electrons, are described. We present thermal ion composition signatures for ICMEs and magnetic clouds from which we derive electron temperatures at the source of the disturbances and we describe additional enhancements in some ion species that are clearly related to the transient source. We describe shock acceleration of 0.3-2.0 MeV nucl(-1) protons and minor ions and the relative inability of some of the shocks to accelerate significant energetic ion populations near 1 AU. We report the characteristics of < 20 MeV nucl(-1) solar energetic ions and < 0.32 MeV electrons and attempt to relate the release of energetic electrons to particular source regions. C1 Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. SW Res Inst, Space Sci & Engn Div, San Antonio, TX 78228 USA. Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA. Aerosp Corp, El Segundo, CA 90245 USA. Florida Inst Technol, Melbourne, FL 32901 USA. Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA. CALTECH, Pasadena, CA 91125 USA. RP Smith, CW (reprint author), Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. OI Moebius, Eberhard/0000-0002-2745-6978 NR 42 TC 26 Z9 28 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD DEC PY 2001 VL 204 IS 1-2 BP 229 EP 254 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 524BU UT WOS:000173992700015 ER PT J AU Whang, YC Burlaga, LF Ness, NF Smith, CW AF Whang, YC Burlaga, LF Ness, NF Smith, CW TI The Bastille Day shocks and merged interaction region SO SOLAR PHYSICS LA English DT Article ID SOLAR-WIND; HELIOSPHERE AB Near 1 AU the solar wind structure associated with the solar flare of 14 July 2000 (Bastille Day) consisted of a large high-speed stream of 15 July and five nearby small streams during a 10-day period. At the leading edge of the large high-speed stream, in less than 6 hours, the flow speed increased from 600 km s(-1) to 1100 km s(-1), the magnetic field intensity increased from 10 nT to 60 nT, and an interaction region was identified. The interaction region was bounded between the pair of a forward shock F and a reverse shock R. Additional forward shocks were also identified at the leading edge of each of the five smaller streams. This paper presents a magnetohydrodynamics (MHD) simulation using ACE plasma and magnetic field data near 1 AU as input to study the radial evolution of the Bastille Day solar wind event. The two shocks, F and R, propagated in opposite directions away from each other in the solar wind frame and interacted with neighboring shocks and streams; the spatial and temporal extent of the interaction region continued to increase with the heliocentric distance. The solar wind was restructured from a series of streams at 1 AU to a huge merged interaction region (MIR) extending over a period of 12 days at 5.5 AU. Throughout the interior of the MIR bounded by the shock pair F and R the magnetic field intensity was a few times stronger than that outside the MIR. The simulation shows how merging of shocks, collision of shocks, and formation of new shocks contributed to the evolution process. C1 Catholic Univ Amer, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. RP Whang, YC (reprint author), Catholic Univ Amer, Washington, DC 20064 USA. NR 5 TC 12 Z9 12 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD DEC PY 2001 VL 204 IS 1-2 BP 255 EP 265 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 524BU UT WOS:000173992700016 ER PT J AU Lepping, RP Berdichevsky, DB Burlaga, LF Lazarus, AJ Kasper, J Desch, MD Wu, CC Reames, DV Singer, HJ Smith, CW Ackerson, KL AF Lepping, RP Berdichevsky, DB Burlaga, LF Lazarus, AJ Kasper, J Desch, MD Wu, CC Reames, DV Singer, HJ Smith, CW Ackerson, KL TI The Bastille Day magnetic clouds and upstream shocks: Near-Earth interplanetary observations SO SOLAR PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; SOLAR-WIND; MAGNETOSPHERE; SPACECRAFT; LASCO AB The energetic charged particle, interplanetary magnetic field, and plasma characteristics of the 'Bastille Day' shock and ejecta/magnetic cloud events at 1 AU occurring over the days 14-16 July 2000 are described. Profiles of MeV (WIND/LEMT) energetic ions help to organize the overall sequence of events from the solar source to 1 AU. Stressed are analyses of an outstanding magnetic cloud (MC2) starting late on 15 July and its upstream shock about 4 hours earlier in WIND magnetic field and plasma data. Also analyzed is a less certain, but likely, magnetic cloud (MC1) occurring early on 15 July; this was separated from MC2 by its upstream shock and many heliospheric current sheet (HCS) crossings. Other HCS crossings occurred throughout the 3-day period. Overall this dramatic series of interplanetary events caused a large multi-phase magnetic storm with min Dst lower than -300 nT. The very fast solar wind speed (greater than or equal to 1100 km s(-1)) in and around the front of MC2 (for near average densities) was responsible for a very high solar wind ram pressure driving in the front of the magnetosphere to geocentric distances estimated to be as low as approximate to 5 R-E, much lower than the geosynchronous orbit radius. This was consistent with magnetic field observations from two GOES satellites which indicated they were in the magnetosheath for extended times. A static force-free field model is used to fit the two magnetic cloud profiles providing estimates of the clouds' physical and geometrical properties. MC2 was much larger than MC1, but their axes were nearly antiparallel, and their magnetic fields had the same left-handed helicity. MC2's axis and its upstream shock normal were very close to being perpendicular to each other, as might be expected if the cloud were driving the shock at the time of observation. The estimated axial magnetic flux carried by MC2 was 52x10(2)0 Mx, which is about 5 times the typical magnetic flux estimated for other magnetic clouds in the WIND data over its first 4 years and is 17 times the flux of MC1. This large flux is due to both the strong axially-directed field of MC2 (46.8 nT on the axis) and the large radius (R-0=0.189 AU) of the flux tube. MC2's average speed is consistent with the expected transit time from a halo-CME to which it is apparently related. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. NOAA, Space Environm Ctr, Boulder, CO 80303 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Emergent Informat Technol, Largo, MD 20774 USA. RP Lepping, RP (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Kasper, Justin/D-1152-2010 OI Kasper, Justin/0000-0002-7077-930X NR 36 TC 42 Z9 42 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD DEC PY 2001 VL 204 IS 1-2 BP 287 EP 305 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 524BU UT WOS:000173992700018 ER PT J AU Burlaga, LF Ness, NF Richardson, JD Lepping, RP AF Burlaga, LF Ness, NF Richardson, JD Lepping, RP TI The Bastille Day shock and merged interaction region at 63 AU: Voyager 2 observations SO SOLAR PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC CLOUDS; LOCAL INTERSTELLAR-MEDIUM; COSMIC-RAY MODULATION; OUTER HELIOSPHERE; SOLAR-WIND; DISTANT HELIOSPHERE; PICKUP PROTONS; PROPAGATION; EVOLUTION; FIELDS AB A transient flow system containing several streams and shocks associated with the Bastille Day 2000 solar event was observed by the WIND and ACE spacecraft at 1 AU. Voyager 2 (V2) at 63 AU observed this flow system after it moved through the interplanetary medium and into the distant heliosphere, where the interstellar pickup protons strongly influence the MHD structures and flow dynamics. We discuss the Voyager 2 magnetic and plasma observations of this event. Increases in the magnetic field strength B, density N, temperature T and speed V were observed at the front of a stream at V2, consistent with presence of a shock related to the Bastille Day shock at 1 AU. However, the jumps occurred in a 16.9-hour data gap, so that the shock was not observed directly, and the properties of the candidate shock cannot be determined precisely. The candidate shock was followed by a merged interaction region (MIR) that moved past V2 for at least 10 days. The first part of this MIR contains a structure that might be a magnetic cloud. Just ahead of the shock there was an abrupt increase in density associated with a decrease in temperature such that the solar wind thermal pressure was constant across it. Just behind the shock there was an abrupt decrease in density associated with a net increase in magnetic field strength. This appears to be a pressure balanced structure in which the interstellar pickup protons make a significant contribution. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. RP Burlaga, LF (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. NR 28 TC 23 Z9 23 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD DEC PY 2001 VL 204 IS 1-2 BP 399 EP 410 DI 10.1023/A:1014269926730 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 524BU UT WOS:000173992700027 ER PT J AU Wang, C Richardson, JD Burlaga, L AF Wang, C Richardson, JD Burlaga, L TI Propagation of the Bastille Day 2000 CME shock in the outer heliosphere SO SOLAR PHYSICS LA English DT Article ID SOLAR-WIND; PICKUP IONS; EVOLUTION; SLOWDOWN; HYDROGEN; ULYSSES; SYSTEM AB The Bastille Day (14 July) 2000 CME is a fast, halo coronal mass ejection event headed earthward. The ejection reached Earth on 15 July 2000 and produced a very significant magnetic storm and widespread aurora. At 1 AU the Wind spacecraft recorded a strong forward shock with a speed jump from similar to 600 to over 1000 km s(-1). About 6 months later, this CME-driven shock arrived at Voyager 2 (similar to 63 AU) on 12 January 2001 with a speed jump of similar to 60 km s(-1). This provides a good opportunity to study the shock propagation in the outer heliosphere. In this study, we employ a 2.5-D MHD numerical model, which takes the interaction of solar wind protons and interstellar neutrals into account, to investigate the shock propagation in detail and compare the model predictions with the Voyager 2 observations. The Bastille Day CME shock undergoes a dramatic change in character from the inner to outer heliosphere. Its strength and propagation speed decay significantly with distance. The model results at the location of Voyager 2 are in good agreement with in-situ observations. C1 MIT, Ctr Space Res, Cambridge, MA 02139 USA. Chinese Acad Sci, Lab Space Weather, Beijing, Peoples R China. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wang, C (reprint author), MIT, Ctr Space Res, Cambridge, MA 02139 USA. NR 22 TC 28 Z9 28 U1 0 U2 2 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD DEC PY 2001 VL 204 IS 1-2 BP 411 EP 421 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 524BU UT WOS:000173992700028 ER PT J AU Cartoixa, X Ting, DZY Daniel, ES McGill, TC AF Cartoixa, X Ting, DZY Daniel, ES McGill, TC TI Theoretical investigations of spin splittings in asymmetric AlSb/InAs/GaSb heterostructures and the possibility of electric field induced magnetization SO SUPERLATTICES AND MICROSTRUCTURES LA English DT Article DE two-dimensional electron gas; 2DEG; InAs; GaSb; AlSb; heterostructure; asymmetric; Rashba; spin splitting ID QUANTUM-WELLS; BAND-STRUCTURE; SEMICONDUCTORS; SPINTRONICS; STATES; HETEROJUNCTIONS; SUPERLATTICES; INJECTION; COHERENCE; INAS AB We use the effective bond orbital model method to examine the spin splitting due to the Rashba effect in AlSb/InAs/GaSb asymmetric heterostructures. We find for the resulting two-dimensional electron gas (2DEG) under study that large theoretical values of the Bychkov-Rashba coefficients in the range of 30 x 10(-10) to 50 x 10(-10) eV . cm can be achieved. Finally, we present a phenomenon that might lead to a direct observation of the Rashba effect. We derive an expression, valid in the diffusive limit, for the spin polarization of the current resulting from a bias parallel to the plane of the quantum well. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Thomas J Watson Lab Appl Phys 12895, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Mayo Clin & Mayo Fdn, Rochester, MN 55905 USA. RP Cartoixa, X (reprint author), CALTECH, Thomas J Watson Lab Appl Phys 12895, Pasadena, CA 91125 USA. NR 34 TC 25 Z9 25 U1 0 U2 5 PU ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0749-6036 J9 SUPERLATTICE MICROST JI Superlattices Microstruct. PD DEC PY 2001 VL 30 IS 6 BP 309 EP 319 DI 10.1006/spmi.2002.1021 PG 11 WC Physics, Condensed Matter SC Physics GA 571EW UT WOS:000176703700003 ER PT J AU Campbell, MR Kirkpatrick, AW Billica, RD Johnston, SL Jennings, R Short, D Hamilton, D Dulchavsky, SA AF Campbell, MR Kirkpatrick, AW Billica, RD Johnston, SL Jennings, R Short, D Hamilton, D Dulchavsky, SA TI Endoscopic surgery in weightlessness - The investigation of basic principles for surgery in space SO SURGICAL ENDOSCOPY-ULTRASOUND AND INTERVENTIONAL TECHNIQUES LA English DT Article ID LAPAROSCOPIC SURGERY; ABDOMINAL-TRAUMA; FIBRIN GLUE; MICROGRAVITY; PNEUMOPERITONEUM; TELEPRESENCE; ULTRASOUND; MEDICINE; CARE AB Background: Performing a surgical procedure in weightlessness, also called 0-gravity (0-g), has been shown to be no more difficult than in a 1-g environment if the requirements for the restraint of the patient, operator, surgical hardware, are observed. The performance of laparoscopic and thorascopic procedures in weightlessness, if feasible, would offer several advantages over the performance of an open operation. Concerns about the feasibility of performing minimally invasive procedures in weightlessness have included impaired visualization from the absence of gravitational retraction of the bowel (laparoscopy) or thoracic organs (thoracoscopy) as well as obstruction and interference from floating debris such as blood, pus, and irrigation fluid. The purpose of this study was to determine the feasibility of performing laparoscopic and thorascopic procedures and the del-ree of impaired surgical endoscopic visualization in weightlessness. Methods: From 1993 to 2000, laparoscopic and thorascopic procedures were performed on 10 anesthetized adult pigs weighing approximately 50 kg in the National Aeronautics and Space Administration (NASA) Microgravity Program using a modified KC-135 airplane. The parabolic simulation system for advanced life support was used in this project, and 20 to 40 parabolas were used for laparoscopic or thorascopic investigation, each containing approximately 30 s of 0-g alternating with 2-g pullouts. The animal model was restrained in the supine position on a floor-level Crew Medical Restraint System, and the abdominal cavity was insufflated with carbon dioxide. The intraabdominal and intrathoracic anatomy was visualized in the 1-g, 0-g, and 2-g periods of parabolic flight. Bleeding was created in the animals, and the behavior of the blood in the abdominal and thoracic cavities was observed. In the thoracic cavity, gas insufflation and mechanical retraction was used at times unilaterally to decrease pulmonary ventilation enough to increase the thoracic domain. Results: Visualization was improved in laparoscopy, from tethering of the bowel by the elastic mesentery, and from the strong tendency for debris and blood to adhere to the abdominal wall because of surface tension forces. The lack of adequate thoracic domain made thorascopy more difficult. Fluid in the thoracic cavity did not impair visualization because the fluid at 0-g does not loculate posteriorly, but disperses along the thoracic wall and mediastinal reflections. Conclusions: Performing minimally invasive procedures instead of open surgical procedures in a weightless environment has theoretical advantages, especially in the ability to prevent cabin atmosphere contamination from surgical fluids (blood, pus, irrigation). Visualization will become more important and practical as the endoscopic hardware is miniaturized from its current form, as endoscopic technology becomes more advanced, and as more surgically capable medical crew officers are present in future long-duration space exploration missions. C1 NASA, Wyle Labs, Houston, TX 77058 USA. RP Campbell, MR (reprint author), NASA, Wyle Labs, Houston, TX 77058 USA. NR 39 TC 31 Z9 32 U1 0 U2 4 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0930-2794 J9 SURG ENDOSC-ULTRAS JI Surg. Endosc.-Ultrason. Interv. Tech. PD DEC PY 2001 VL 15 IS 12 BP 1413 EP 1418 DI 10.1007/s004640080178 PG 6 WC Surgery SC Surgery GA 500ZQ UT WOS:000172658900009 PM 11965456 ER PT J AU Vander Wal, RL Hall, LJ AF Vander Wal, RL Hall, LJ TI Flame synthesis of Fe catalyzed single-walled carbon nanotubes and Ni catalyzed nanofibers: growth mechanisms and consequences SO CHEMICAL PHYSICS LETTERS LA English DT Article ID IRON AB Flame synthesis of single-walled carbon nanotubes and nanofibers is demonstrated using a pyrolysis flame configuration. Fe reacts preferentially with CO/H-2/He mixtures to produce single-walled nanotubes (SWNTs). In contrast, Ni reacts preferentially with C2H2/H-2/He mixtures to yield nanofibers. Both catalyst metals exhibit a marked size dependent reactivity towards these reactant gas mixtures. The yarmulke mechanism and a carbon solvation/diffusion/ precipitation account for the different catalyzed products, SWNTs and nanofibers. respectively, Consequences of the size dependent reactivities of Fe and Ni nanoparticles and the respective growth mechanisms for the SWNTs and nanofibers are discussed. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA Glenn, NCMR, Cleveland, OH 44135 USA. RP NASA Glenn, NCMR, M-S 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. EM randy@rvander.lerc.nasa.gov NR 29 TC 42 Z9 42 U1 1 U2 43 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 EI 1873-4448 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD NOV 30 PY 2001 VL 349 IS 3-4 BP 178 EP 184 DI 10.1016/S0009-2614(01)01198-8 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 499XH UT WOS:000172595600003 ER PT J AU Porcelli, D Woolum, D Cassen, P AF Porcelli, D Woolum, D Cassen, P TI Deep Earth rare gases: initial inventories, capture from the solar nebula, and losses during Moon formation SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article DE noble gases; solar nebula; Moon; mantle; impact ID PRIMORDIAL NOBLE-GASES; STATE UPPER-MANTLE; EARLY EVOLUTION; MASS-TRANSFER; HELIUM; XENON; ATMOSPHERE; ARGON; NEON; COMPONENT AB The implications of mantle rare gas characteristics for both the acquisition of rare gases from the solar nebula and subsequent losses to space are examined. There is at least one deep mantle reservoir rich in He-3 and Ne that was trapped early in Earth history. with minimum concentrations obtained by closed system calculations. Ne isotopes indicate the presence of a component that has a solar composition. Xe isotopes indicate that extensive late losses occurred from the mantle as well as from the atmosphere. Calculations based on a simple two-stage evolution provide times of losses of up to similar to 100 Ma after the formation of the solar system from both the mantle and the atmosphere, These losses appear to have depleted the rare gases by greater than or equal to 97%, therefore, there originally was at least two orders of magnitude more rare gases than now present. Mechanisms for the capture of rare gases soon after the start of the solar system into the deep Earth (or Earth-forming materials) must provide these high initial concentrations, presumably in the high-energy environment of planetary accretion where strong degassing of solids might be expected to have occurred. A mechanism that satisfies these requirements is the dissolution in a magma ocean of rare gases from a dense primary atmosphere. A massive atmosphere of solar composition would have been captured if the Earth had formed prior to dispersal of the solar nebula. The underlying mantle would have melted due to the energy of accretion and the blanketing effect of this atmosphere. Rare gases would then have entered the molten Earth by dissolution at the surface and downward advection. For typical solubility coefficients, a total pressure of similar to 100 atm and surface temperatures of > similar to 2500 degreesC are required to dissolve sufficient rare gases to account for the initial lower mantle concentrations. While Xe in the mantle is isotopically exchanging with the primary atmosphere. it will be buffered to a solar composition, therefore., somewhat less Xe must be trapped prior to the late loss event for longer periods of exchange. As solidification of the mantle proceeded outward during cooling, the distributions of retained rare gases would have been determined by the history of surface pressure and temperature during the coupled cooling of the Earth and atmosphere. The giant impact proposed for Moon formation may have been responsible for the inferred substantial and late gas losses from the deep mantle as well as from the atmosphere. Constraints on the timing of Moon formation derived from Hf-W systematics and simulations of the giant impact are consistent with the Xe isotope constraints for gas loss. (C) 2001 Elsevier Science B.V. All rights reserved. C1 ETH Zurich, Inst Isotope Geol & Mineral Resources, CH-8092 Zurich, Switzerland. Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92834 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mt View, CA 94043 USA. RP Porcelli, D (reprint author), ETH Zurich, Inst Isotope Geol & Mineral Resources, NO C611,Sonneggstr 5, CH-8092 Zurich, Switzerland. NR 63 TC 43 Z9 45 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD NOV 30 PY 2001 VL 193 IS 1-2 BP 237 EP 251 DI 10.1016/S0012-821X(01)00493-9 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 499MU UT WOS:000172575600020 ER PT J AU Stoica, A AF Stoica, A TI Robot fostering techniques for sensory-motor development of humanoid robots SO ROBOTICS AND AUTONOMOUS SYSTEMS LA English DT Article DE robot; development; humanoid; imitation; fostering AB The research efforts addressing the control of robot behavior have been polarized; most robots re either fully guided through "strong" programming, or given a few learning algorithms and left alone to explore the world. This paper explores the area in-between, looking at robot fostering, referring to techniques by which skills can be transferred to robots through a close interaction with humans. While robot fostering can be the basis of interaction with a variety of robotic shapes, it is most natural and human-friendly when the robot apprentices are anthropomorphic/humanoid. Fostering techniques discussed here include teaching/learning by imitation, teaching by description/explanation, reinforcement, aid and collaboration. The paper illustrates an experiment in teaching/learning by imitation. The human fosters the robot by first imitating its uncoordinated arm movements, thus helping the robot develop its sensory-motor associative system. The human then shows arm movements and the robot visually tracks them; consecutively, the robot is able to learn arm movements by imitation. Fostering techniques, in addition to robot learning/acquisition techniques and more efficient man-machine interaction are considered key elements contributing to the nascence of a new research field, developmental robotics, which would focus on the robotics counterpart of human cognitive and motor development. (C) 2001 Published by Elsevier Science B.V. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Stoica, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 26 TC 7 Z9 7 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8890 J9 ROBOT AUTON SYST JI Robot. Auton. Syst. PD NOV 30 PY 2001 VL 37 IS 2-3 BP 127 EP 143 DI 10.1016/S0921-8890(01)00154-3 PG 17 WC Automation & Control Systems; Computer Science, Artificial Intelligence; Robotics SC Automation & Control Systems; Computer Science; Robotics GA 495XD UT WOS:000172364900004 ER PT J AU Streets, DG Jiang, KJ Hu, XL Sinton, JE Zhang, XQ Xu, DY Jacobson, MZ Hansen, JE AF Streets, DG Jiang, KJ Hu, XL Sinton, JE Zhang, XQ Xu, DY Jacobson, MZ Hansen, JE TI Climate change - Recent reductions in China's greenhouse gas emissions SO SCIENCE LA English DT Editorial Material C1 Argonne Natl Lab, Decis & Informat Sci Div, Argonne, IL 60439 USA. Energy Res Inst, Ctr Energy Environm & Climate Change, Beijing 100038, Peoples R China. Univ Calif Berkeley, Lawrence Berkeley Lab, Dept Energy Anal, Berkeley, CA 94720 USA. Chinese Acad Forestry, Forest Ecol & Environm Inst, Beijing 100091, Peoples R China. Stanford Univ, Dept Civil & Environm Engn, Stanford, CA 94305 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Streets, DG (reprint author), Argonne Natl Lab, Decis & Informat Sci Div, 9700 S Cass Ave, Argonne, IL 60439 USA. NR 19 TC 94 Z9 123 U1 6 U2 40 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD NOV 30 PY 2001 VL 294 IS 5548 BP 1835 EP + DI 10.1126/science.1065226 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 497PQ UT WOS:000172465000028 PM 11729288 ER PT J AU Santer, BD Wigley, TML Doutriaux, C Boyle, JS Hansen, JE Jones, PD Meehl, GA Roeckner, E Sengupta, S Taylor, KE AF Santer, BD Wigley, TML Doutriaux, C Boyle, JS Hansen, JE Jones, PD Meehl, GA Roeckner, E Sengupta, S Taylor, KE TI Accounting for the effects of volcanoes and ENSO in comparisons of modeled and observed temperature trends SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTHROPOGENIC OZONE DEPLETION; SOUTHERN-OSCILLATION INDEX; GENERAL-CIRCULATION MODEL; TRANSIENT CLIMATE-CHANGE; SURFACE AIR-TEMPERATURE; EL-NINO; 20TH-CENTURY TEMPERATURE; AEROSOL VARIATIONS; PINATUBO ERUPTION; TIME-SERIES AB Several previous studies have attempted to remove the effects of explosive volcanic eruptions and El Nino-Southern Oscillation (ENSO) variability from time series of globally averaged surface and tropospheric temperatures. Such work has largely ignored the nonzero correlation between volcanic signals and ENSO. Here we account for this, collinearity using an iterative procedure. We remove estimated volcano and ENSO signals from the observed global mean temperature data, and then calculate trends over 1979-1999 in the residuals. Residual trends are sensitive to the choice of index used for removing ENSO effects and to uncertainties in key volcanic parameters. Despite these sensitivities, residual surface and lower tropospheric (2LT) trends are almost always larger than trends in the raw observational data. After removal of volcano and ENSO effects, the differential warming between the surface and lower troposphere is generally reduced. These results suggest that the net effect of volcanoes and ENSO over 1979-1999 was to reduce globally averaged surface and tropospheric temperatures and cool the troposphere by more than the surface. ENSO and incomplete volcanic forcing effects can hamper reliable assessment of the true correspondence between modeled and observed trends. In the second part of our study, we remove these effects from model data and compare simulated and observed residual trends. Residual temperature trends are not significantly different at the surface. In the lower troposphere the statistical significance of trend differences depends on the experiment considered, the choice of ENSO index, and the volcanic signal decay time. The simulated difference between surface and tropospheric warming rates is significantly smaller than observed in 51 out of 54 cases considered. We also examine multiple realizations of model experiments with relatively complete estimates of natural and anthropogenic forcing. ENSO and volcanic. effects are not removed from these integrations. As in the case of residual trends, model and observed raw trends are in good agreement at the surface but differ significantly in terms of the trend differential between the surface and lower troposphere. Observed and simulated lower tropospheric trends are not significantly different in 17 out of 24 cases. Our study highlights the large uncertainties inherent in removing volcano and ENSO effects from atmospheric temperature data. It shows that statistical removal of these effects improves the, correspondence between modeled and observed temperature trends over the satellite era. Accounting for volcanoes and ENSO cannot fully explain the observed warming of the surface relative to the lower troposphere, or why this differential warming is not reproduced in the model simulations considered here. C1 Lawrence Livermore Natl Lab, Program Climate Model Diag & Intercomparison, Livermore, CA 94550 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Univ E Anglia, Climat Res Unit, Norwich NR4 7TJ, Norfolk, England. Natl Ctr Atmospher Res, Boulder, CO 80303 USA. Max Planck Inst Meteorol, D-20146 Hamburg, Germany. Lawrence Livermore Natl Lab, Engn Directorate, Livermore, CA 94550 USA. RP Santer, BD (reprint author), Lawrence Livermore Natl Lab, Program Climate Model Diag & Intercomparison, POB 808,Mail Stop L-264, Livermore, CA 94550 USA. EM santer1@llnl.gov RI Wigley, Tom/B-4705-2008; Jones, Philip/C-8718-2009; Taylor, Karl/F-7290-2011; Santer, Benjamin/F-9781-2011 OI Jones, Philip/0000-0001-5032-5493; Taylor, Karl/0000-0002-6491-2135; NR 62 TC 65 Z9 65 U1 2 U2 14 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2001 VL 106 IS D22 BP 28033 EP 28059 DI 10.1029/2000JD000189 PG 27 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 495TE UT WOS:000172355800001 ER PT J AU Rind, D Lerner, J McLinden, C AF Rind, D Lerner, J McLinden, C TI Changes of tracer distributions in the doubled CO2 climate SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; MIDDLE ATMOSPHERE; DIAGNOSTIC-TOOL; GREENHOUSE-GAS; ONLINE TRACERS; STRATOSPHERE; TROPOSPHERE; TRANSPORT; DYNAMICS; EXCHANGE AB Changes in tracer distributions in the troposphere and stratosphere are calculated from a control and doubled CO2 climate simulation run with the Goddard Institute for Space Studies Global Climate Middle Atmosphere Model. Transport changes are assessed using seven on-line tracers. Results show that interhemispheric transport is reduced by 5% along with a reduction in the Hadley circulation. Tropical transport from the troposphere into the stratosphere increases by some 30% associated with an increase in the stratospheric subtropical residual circulation. The tropical pipe becomes significantly more leaky, and greater transport into the lowermost stratosphere in the subtropics appears to be occurring, possibly in conjunction with a poleward shift in wave energy convergences. An increase in the high-latitude lower stratosphere residual circulation reduces the stratospheric residence time of extratropical injections such as bomb C-14 by 11%. Vertical mixing within the troposphere by convection increases, reducing low level concentrations of tracers. The Hadley cell change is affected by the latitudinal gradient of tropical warming. The high-latitude lower stratosphere residual circulation change depends on the latitudinal gradient of the extratropical warming. Increased penetrating convection to the upper troposphere and the intensified residual circulation in the tropical upper troposphere/lower stratosphere appear to be the most robust of these results, with a magnitude that depends upon the degree of tropical warming. The consequence of this circulation change is to increase trace gas concentrations in the stratosphere and to decrease them in the troposphere for those species that have tropospheric sources. C1 Columbia Univ, NASA, Goddard Inst Space Studies, SGT Corp, New York, NY 10025 USA. Columbia Univ, NASA, Goddard Inst Space Studies, SGT Corp, New York, NY 10025 USA. Univ Calif Irvine, Earth Syst Sci Dept, Irvine, CA USA. RP Rind, D (reprint author), Columbia Univ, NASA, Goddard Inst Space Studies, SGT Corp, 2880 Broadway, New York, NY 10025 USA. EM drind@giss.nasa.gov; jlerner@giss.nasa.gov; chris.mclinden@ec.gc.ca RI McLinden, Chris/A-7710-2010 OI McLinden, Chris/0000-0001-5054-1380 NR 29 TC 44 Z9 44 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2001 VL 106 IS D22 BP 28061 EP 28079 DI 10.1029/2001JD000439 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 495TE UT WOS:000172355800002 ER PT J AU Halpern, D Hung, CW AF Halpern, D Hung, CW TI Satellite observations of the southeast Pacific intertropical convergence zone during 1993-1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SEA-SURFACE TEMPERATURE; INTERANNUAL VARIABILITY; TROPICAL PACIFIC; CLIMATOLOGY; WIND; SCATTEROMETER; ITCZ AB An intertropical convergence zone in the southeast Pacific Ocean is described from monthly mean 1 degrees X 1 degrees ocean vector wind, rainfall, sea surface temperature, and integrated water vapor measurements recorded from satellites. Time interval of the investigation was January 1993 to December 1998, when ocean and atmosphere conditions during 1993-1996 were normal compared to the 1997-1998 El Nino. The southeast Pacific intertropical convergence zone (SITCZ) occurred in March-April at 8 degreesS-2 degreesS, 130 degreesW-90 degreesW. During 1993-1996 the average March-April values of SITCZ surface, wind convergence, rain rate, sea surface temperature, and integrated water vapor were 3.3 X 10(-6) s(-1), 3.3 mm d(-1), 27.3 degreesC, and 45.3 mm, respectively. A statistical model of the monthly mean observations predicted rainfall greater than the 2 mm d(-1) threshold when surface wind convergence was greater than the 1.5 X 10(-6) s(-1) threshold and sea surface temperature was above 27 degreesC. During non-El Nino conditions, SITCZ sea surface temperature was greater than sea surface temperature in the 2 degreesS-2 degreesN equatorial band, with maximum difference in March-April which would create a surface wind convergence larger in March-April compared to other months. The Intertropical Convergence Zone (ITCZ), which occurred north of the equator throughout the year, and the SITCZ were separated by divergent wind, low (<2 min d(-1)) rainfall, and cold (< 27 degreesC) surface water, except during the intense 1998 El Nino. The rain rate of the ITCZ was minimum in March-April during 1993-1996 and comparable to the SITCZ rain rate. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90095 USA. RP Halpern, D (reprint author), CALTECH, Jet Prop Lab, MS 300-323, Pasadena, CA 91109 USA. EM david.halpern@jpl.nasa.gov NR 21 TC 20 Z9 20 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2001 VL 106 IS D22 BP 28107 EP 28112 DI 10.1029/2000JD000056 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 495TE UT WOS:000172355800006 ER PT J AU Stephens, GL Engelen, RJ Vaughan, M Anderson, TL AF Stephens, GL Engelen, RJ Vaughan, M Anderson, TL TI Toward retrieving properties of the tenuous atmosphere using space-based lidar measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TO-BACKSCATTER RATIO; AEROSOL EXTINCTION; POLARIZATION LIDAR; RAMAN LIDAR; CLOUD; PROFILES AB This paper introduces a method that can incorporate different information into the lidar retrieval problem as an attempt to address the backscatter-to-extinction ambiguity that plagues the usefulness of lidar backscattering measurements. The approach, suited for application to spaceborne lidar data, inverts the lidar equation via an optimal estimation method. This method is illustrated using three examples drawn from LITE data. Retrievals using only lidar backscatter as input were compared to retrievals performed using an iterative solution to the lidar inversion with the same input. The two methods produced essentially identical results. The new method, however, offers a number of advantages compared to other methods, including (1) the ability to incorporate different kinds of information under a common retrieval philosophy. This feature is illustrated with the formal introduction of optical depth into the lidar inversion. In this paper, optical depth information, derived from the Idar transmission estimates, is combined with backscatter measurements making it possible to retrieve the backscatter-to-extinction ratio in addition to extinction profiles given certain caveats noted in the paper. (2) The method provides a number of ways for evaluating the quality of the retrieval. Notably, the retrieval approach predicts full error diagnostics identifying sources of error due to measurement uncertainty (instrument noise and calibration uncertainty), model error (containing all the assumptions built into the lidar equation and its parameters), as well as a priori error due to the influence of compiled databases on lidar backscatter of aerosol and cloud. When no optical depth information is available, the retrieval errors are largely dominated by the (large) uncertainty attached to the backscatter-to-extinction coefficient k. Under these circumstances the retrievals are only meaningful to the extent that k and its related uncertainty is known. When optical depth is introduced as a form of measurement, the error contributions shift to the extent that retrieval errors become dominated by the measurement error attached to the optical depth itself. C1 Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Washington, Joint Inst Study Atmosphere & Oceans, Seattle, WA 90995 USA. RP Stephens, GL (reprint author), Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. EM stephens@atinos.colostate.edu NR 38 TC 20 Z9 20 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2001 VL 106 IS D22 BP 28143 EP 28157 DI 10.1029/2001JD000632 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 495TE UT WOS:000172355800009 ER PT J AU Prigent, C Pardo, JR Mishchenko, MI Rossow, WB AF Prigent, C Pardo, JR Mishchenko, MI Rossow, WB TI Microwave polarized signatures generated within cloud systems: Special Sensor Microwave Imager (SSM/I) observations interpreted with radiative transfer simulations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PHYSICAL PRECIPITATION RETRIEVAL; AXIALLY-SYMMETRICAL PARTICLES; LIQUID-WATER PATH; PASSIVE MICROWAVE; BRIGHTNESS-TEMPERATURE; ATMOSPHERIC TRANSMISSION; SATELLITE MEASUREMENTS; LIGHT-SCATTERING; SNOW COVER; ICE AB Special Sensor Microwave Imager (SSM/I) observations in cloud systems are studied over the tropics. Over optically thick cloud systems, the presence of polarized signatures at 37 and 85 GHz is evidenced and analyzed with the help of cloud top temperature and optical thickness extracted from visible and IR satellite observations. Scattering signatures at 85 GHz (TbV(85)less than or equal to 250 K) are associated with polarization differences greater than or equal to 6 K similar to 50% of the time over ocean and similar to 40% over land. In addition, over thick clouds the polarization difference at 37 GHz rarely is negligible. The polarization differences at 37 and 85 GHz do not stem from the surface but are generated in regions of relatively homogeneous clouds having high liquid water content. To interpret the observations, a radiative transfer model that includes the scattering by nonspherical particles is developed, based on the T matrix approach and using the doubling and adding method. In addition to handling randomly and perfectly oriented particles this model can also simulate the effect of partial orientation of the hydrometeors. Microwave brightness temperatures are simulated at SSM/I frequencies and are compared with the observations. Polarization differences of similar to 2 K can be simulated at 37 GHz over a rain layer, even using spherical drops. The polarization difference is larger for oriented nonspherical particles. The 85 GHz simulations are very sensitive to the ice phase of the cloud. Simulations with spherical particles or with randomly oriented nonspherical ice particles cannot replicate the observed polarization differences. However, with partially oriented nonspherical particles the observed polarized signatures at 85 GHz are explained, and the sensitivity of the scattering characteristics to the particle size, asphericity, and orientation is analyzed. Implications on rain and ice retrievals are discussed. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Prigent, C (reprint author), Observ Paris, Ctr Natl Rech Sci, Dept Radioastronomie Millimetr, Paris, France. EM catherine.prigent@obspm.fr; pardo@isis.iem.csic.es; mmishchenko@giss.nasa.gov; wrossow@giss.nasa.gov RI Rossow, William/F-3138-2015; Mishchenko, Michael/D-4426-2012 NR 58 TC 27 Z9 27 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2001 VL 106 IS D22 BP 28243 EP 28258 DI 10.1029/2001JD900242 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 495TE UT WOS:000172355800017 ER PT J AU Lee, KM Park, JH Massie, ST Choi, W AF Lee, KM Park, JH Massie, ST Choi, W TI Extinction coefficients and properties of Pinatubo aerosol determined from Halogen Occultation Experiment (HALOE) data SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC OZONE; OPTICAL-CONSTANTS; SIZE DISTRIBUTION; MOUNT-PINATUBO; VOLCANIC AEROSOL; SURFACE-AREA; VALIDATION; LARAMIE; VOLATILITY; EVOLUTION AB Relative extinction coefficients as a function of wavelength are determined for stratospheric aerosols from the Mount Pinatubo eruptions in June of 1991, using the Halogen Occultation Experiment (HALOE) data at latitudes 20 degrees -55 degrees in the northern hemisphere from November 1991 to February 1992. Extinction coefficients at each of the eight HALOE channels are obtained from the ratio of two transmittance profiles of consecutive occultation measurements separated by 25 degrees longitude, one loaded with aerosols larger than the other during the early stage of aerosol dispersion after the eruptions. These coefficients are compared to theoretical Mie calculation values. Composition and a single mode particle size distribution are derived as a function of altitude. The retrievals indicate that the weight percentage of H2SO4 for 45 occultation cases is larger than the equilibrium value by about 5 wt %, while the size distribution parameters are within the range of those measured in situ at Laramie, Wyoming. C1 Kyungpook Natl Univ, Dept Astronomy & Atmospher Sci, Buk Gu, Taegu 702701, South Korea. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80307 USA. Seoul Natl Univ, Sch Earth & Environm Sci, Seoul 151742, South Korea. RP Lee, KM (reprint author), Kyungpook Natl Univ, Dept Astronomy & Atmospher Sci, Buk Gu, 1370 Sankyuck Dong, Taegu 702701, South Korea. EM kmlee@bh.knu.ac.kr; j.h.park@larc.nasa.gov; massie@acd.ucar.edu; wchoi@plaza.smi.ac.kr NR 30 TC 6 Z9 6 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2001 VL 106 IS D22 BP 28333 EP 28345 DI 10.1029/2000JD000251 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 495TE UT WOS:000172355800022 ER PT J AU Pandithurai, G Pinker, RT Dubovik, O Holben, BN Aro, TO AF Pandithurai, G Pinker, RT Dubovik, O Holben, BN Aro, TO TI Remote sensing of aerosol optical characteristics in sub-Sahel, West Africa SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SKY RADIANCE MEASUREMENTS; SAHARAN DUST; ATMOSPHERIC DUST; REFRACTIVE-INDEX; SMOKE PARTICLES; HARMATTAN DUST; RADIATIVE CHARACTERISTICS; WAVE DISTURBANCES; MINERAL AEROSOL; COMPLEX INDEX AB We have determined the characteristics of sub-Sahelian aerosols from a 2-year record of continuous ground-based measurements, made at the University of Ilorin, Ilorin (08 degrees 19'N, 04 degrees 20'E), Nigeria, in cooperation with the Aerosol Robotic Network. Observations of spectral aerosol optical depths during the dusty harmattan season indicate more than a twofold increase, when compared to other seasons. Retrieved columnar volume size distributions show the existence of bimodality with a dominant coarse mode. The retrieved size distributions were grouped according to different ranges of aerosol optical depths to characterize the aerosols for this particular region. Monthly means of retrieved single-scattering albedos show a sharp decrease from similar to0.95 to similar to0.85 at 500 nm from the preharmattan to the harmattan season when biomass burning is also practiced, increasing the presence of absorbing aerosols. On the basis of these comprehensive observations, we propose to augment existing desert aerosol models, as presented in the literature, to better characterize the dust outbreak season in West Africa, which is quite prolonged and overlaps with the biomass burning season. C1 Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Indian Inst Trop Meteorol, Pune, Maharashtra, India. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. Univ Ilorin, Ilorin, Nigeria. RP Pinker, RT (reprint author), Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. EM pinker@atmos.umd.edu RI Dubovik, Oleg/A-8235-2009; Pinker, Rachel/F-6565-2010; OI Dubovik, Oleg/0000-0003-3482-6460; Pandithurai, G/0000-0001-7324-3773 NR 66 TC 13 Z9 13 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2001 VL 106 IS D22 BP 28347 EP 28356 DI 10.1029/2001JD900234 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 495TE UT WOS:000172355800023 ER PT J AU Ramanathan, V Crutzen, PJ Lelieveld, J Mitra, AP Althausen, D Anderson, J Andreae, MO Cantrell, W Cass, GR Chung, CE Clarke, AD Coakley, JA Collins, WD Conant, WC Dulac, F Heintzenberg, J Heymsfield, AJ Holben, B Howell, S Hudson, J Jayaraman, A Kiehl, JT Krishnamurti, TN Lubin, D McFarquhar, G Novakov, T Ogren, JA Podgorny, IA Prather, K Priestley, K Prospero, JM Quinn, PK Rajeev, K Rasch, P Rupert, S Sadourny, R Satheesh, SK Shaw, GE Sheridan, P Valero, FPJ AF Ramanathan, V Crutzen, PJ Lelieveld, J Mitra, AP Althausen, D Anderson, J Andreae, MO Cantrell, W Cass, GR Chung, CE Clarke, AD Coakley, JA Collins, WD Conant, WC Dulac, F Heintzenberg, J Heymsfield, AJ Holben, B Howell, S Hudson, J Jayaraman, A Kiehl, JT Krishnamurti, TN Lubin, D McFarquhar, G Novakov, T Ogren, JA Podgorny, IA Prather, K Priestley, K Prospero, JM Quinn, PK Rajeev, K Rasch, P Rupert, S Sadourny, R Satheesh, SK Shaw, GE Sheridan, P Valero, FPJ TI Indian Ocean Experiment: An integrated analysis of the climate forcing and effects of the great Indo-Asian haze SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLOUD CONDENSATION NUCLEI; ANTHROPOGENIC SULFATE AEROSOLS; GLOBAL RADIATION BUDGET; ATMOSPHERIC AEROSOLS; CARBONACEOUS AEROSOLS; AIRBORNE MEASUREMENTS; STRATOCUMULUS CLOUDS; TROPOSPHERIC AEROSOL; EFFECTIVE RADIUS; NATIONAL CENTER AB Every year, from December to April, anthropogenic haze spreads over most of the North Indian Ocean, and South and Southeast Asia. The Indian Ocean Experiment (INDOEX) documented this Indo-Asian haze at scales ranging from individual particles to its contribution to the regional climate forcing. This study integrates the multiplatform. observations (satellites, aircraft, ships, surface stations, and balloons) with one- and four-dimensional models to derive the regional aerosol forcing resulting from the direct, the semidirect and the two indirect effects. The haze particles consisted of several inorganic and carbonaceous species, including absorbing black carbon clusters, fly ash, and mineral dust. The most striking result was the large loading of aerosols over most of the South Asian region and the North Indian Ocean. The January to March 1999 visible optical depths were about 0.5 over most of the continent and reached values as large as 0.2 over the equatorial Indian ocean due to long-range transport. The aerosol layer extended as high as 3 km. Black carbon contributed about 14% to the fine particle mass and 11% to the visible optical depth. The single-scattering albedo estimated by several independent methods was consistently around 0.9 both inland and over the open ocean. Anthropogenic sources contributed as much as 80% (+/- 10%) to the aerosol loading and the optical depth. The in situ data, which clearly support the existence of the first indirect effect (increased aerosol concentration producing more cloud drops with smaller effective radii), are used to develop a composite indirect effect scheme. The Indo-Asian aerosols impact the radiative forcing through a complex set of heating (positive forcing) and cooling (negative forcing) processes. Clouds and black carbon emerge as the ma or players. The dominant factor, however, is the large negative forcing (-20 +/- 4 W m(-2)) at the surface and the comparably large atmospheric heating. Regionally, the absorbing haze decreased the surface solar radiation by an amount comparable to 50% of the total ocean heat flux and nearly doubled the lower tropospheric solar heating. We demonstrate with a general circulation model how this additional heating significantly perturbs the tropical rainfall patterns and the hydrological cycle with implications to global climate. C1 Univ Calif San Diego, Scripps Inst Oceanog, Ctr Atmospher Sci, La Jolla, CA 92037 USA. Max Planck Inst Chem, D-55020 Mainz, Germany. Natl Phys Lab, New Delhi 110012, India. Inst Tropospher Res, D-04318 Leipzig, Germany. Arizona State Univ, Dept Geol & Chem, Tempe, AZ 85287 USA. Indiana Univ, Dept Chem, Bloomington, IN 47401 USA. Georgia Inst Technol, Sch Civil & Environm Engn, Atlanta, GA 30332 USA. Univ Hawaii, Dept Oceanog, Honolulu, HI 96822 USA. Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Lab Sci Climat & Environm, F-91191 Gif Sur Yvette, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Nevada, Desert Res Inst, Reno, NV 89506 USA. Phys Res Lab, Ahmadabad 380009, Gujarat, India. Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Univ Calif Riverside, Dept Chem, Riverside, CA 92521 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Miami, FL 33149 USA. NOAA, Pacific Marine Environm Lab, Seattle, WA 98115 USA. Vikram Sarabhai Space Ctr, Space Phys Lab, Trivandrum 695022, Kerala, India. Meteorol Dynam Lab, F-75005 Paris, France. Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA. RP Ramanathan, V (reprint author), Univ Calif San Diego, Scripps Inst Oceanog, Ctr Atmospher Sci, La Jolla, CA 92037 USA. EM ram@fiji.ucsd.edu RI Heymsfield, Andrew/E-7340-2011; Crutzen, Paul/F-6044-2012; Prather, Kimberly/A-3892-2008; Collins, William/J-3147-2014; Ogren, John/M-8255-2015; Andreae, Meinrat/B-1068-2008; Lelieveld, Johannes/A-1986-2013; Quinn, Patricia/R-1493-2016; OI Prather, Kimberly/0000-0003-3048-9890; Collins, William/0000-0002-4463-9848; Ogren, John/0000-0002-7895-9583; Andreae, Meinrat/0000-0003-1968-7925; Quinn, Patricia/0000-0003-0337-4895; Prospero, Joseph/0000-0003-3608-6160; McFarquhar, Greg/0000-0003-0950-0135 NR 87 TC 782 Z9 809 U1 13 U2 158 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2001 VL 106 IS D22 BP 28371 EP 28398 DI 10.1029/2001JD900133 PG 28 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 495TE UT WOS:000172355800026 ER PT J AU Eck, TF Holben, BN Dubovik, O Smirnov, A Slutsker, I Lobert, JM Ramanathan, V AF Eck, TF Holben, BN Dubovik, O Smirnov, A Slutsker, I Lobert, JM Ramanathan, V TI Column-integrated aerosol optical properties over the Maldives during the northeast monsoon for 1998-2000 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPICAL INDIAN-OCEAN; SKY RADIANCE MEASUREMENTS; BIOMASS BURNING AEROSOLS; PHYSICAL-PROPERTIES; SIZE DISTRIBUTION; SMOKE PARTICLES; WATER-VAPOR; AERONET; BRAZIL; DEPTH AB Measurements made during the Indian Ocean Experiment (INDOEX) have shown the presence of large aerosol loadings over the region of the northern Indian Ocean and Arabian Sea. In recent years there has been significant interannual variability in the magnitude of this aerosol loading during the NE monsoon months of. January-April. Monitoring of the integrated atmospheric column effective aerosol optical properties was initiated in early 1998 and continued in 2000 on the island of Kaashidhoo in the Republic of Maldives. An Aerosol Robotic Network Sun-sky radiometer at the Kaashidhoo Climate Observatory made spectral measurements of the direct Sun and directional sky radiances which were utilized to infer spectral aerosol optical depths tau (a), single scattering albedos, asymmetry factors, and aerosol size distributions. Monthly average aerosol optical depths at 500 nm varied by more than a factor of 2 during January through April for the 3 years that were investigated, 1998-2000. Interannual variations in the monthly mean Angstrom wavelength exponent were also observed, resulting from differences in the bimodal aerosol size distributions. Spectral variations in the Angstrom wavelength exponent were observed, especially at high aerosol optical depths when fine mode aerosols dominated over the optical influence of coarse-mode aerosols. Some differences in spectral single scattering albedo and asymmetry factor were observed for 1999 versus 2000 in the infrared wavelengths, but with relatively little change in the visible wavelengths. The spectral variation in the retrieved single scattering albedo was large, with approximately linear wavelength dependence averaging from 0.91 at 440 nm to 0.83 at 1020 nm for January-March 1999 for observations where tau (a) at 440 nm >0.4. C1 Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Goddard Earth Sci & Technol Ctr, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. Univ Calif San Diego, Scripps Inst Oceanog, Ctr Clouds Chem & Climate, La Jolla, CA 92037 USA. RP Eck, TF (reprint author), Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Goddard Earth Sci & Technol Ctr, Mail Code 923, Greenbelt, MD 20771 USA. EM tom@aeronet.gsfc.nasa.gov RI Dubovik, Oleg/A-8235-2009; Smirnov, Alexander/C-2121-2009; ECK, THOMAS/D-7407-2012 OI Dubovik, Oleg/0000-0003-3482-6460; Smirnov, Alexander/0000-0002-8208-1304; NR 35 TC 112 Z9 117 U1 1 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2001 VL 106 IS D22 BP 28555 EP 28566 DI 10.1029/2001JD000786 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 495TE UT WOS:000172355800038 ER PT J AU Qiu, Y Gogna, P Forouhar, S Stintz, A Lester, LF AF Qiu, Y Gogna, P Forouhar, S Stintz, A Lester, LF TI High-performance InAs quantum-dot lasers near 1.3 mu m SO APPLIED PHYSICS LETTERS LA English DT Article ID HIGH CHARACTERISTIC TEMPERATURE; ROOM-TEMPERATURE; LOW-THRESHOLD; 1.3-MU-M; EMISSION; LAYER; GAIN AB High-performance quantum dot (QD) lasers near 1.3 mum were fabricated using four stacks of InAs QDs embedded within strained InGaAs quantum wells as an active region and a reactive-ion-etched 5-mum-ridge waveguide design. For a 1.5-mm-long cavity QD laser, ground-state continuous-wave (cw) lasing has been achieved with a single facet output power of 15 mW at temperatures as high as 100 degreesC, while at room temperature having a differential quantum efficiency of 55% and a single facet output power of 50 mW. The characteristic temperature T-0 for ground-state cw lasing is 78 K up to our temperature measurement limit of 100 degreesC. (C) 2001 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ New Mexico, Ctr High Technol Mat, Albuquerque, NM 87106 USA. RP Qiu, Y (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 74 Z9 76 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD NOV 26 PY 2001 VL 79 IS 22 BP 3570 EP 3572 DI 10.1063/1.1421428 PG 3 WC Physics, Applied SC Physics GA 493CL UT WOS:000172204400004 ER PT J AU Duxbury, NS Nealson, KH Romanovsky, VE AF Duxbury, NS Nealson, KH Romanovsky, VE TI On the possibility of clathrate hydrates on the Moon SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CARBON-DIOXIDE; ICE; STABILITY; DEPOSITS; MERCURY AB One of the most important inferences of the Lunar Prospector mission data was the existence of subsurface water ice in the permanently shadowed craters near both lunar poles [Feldman et al., 1998]. We propose and substantiate an alternative explanation that hydrogen can exist in the shallow lunar subsurface in the form of clathrate hydrates: CH4 . 6H(2)O and/or CO2 . 6H(2)O. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Alaska, Inst Geophys, Fairbanks, AK 99701 USA. RP Duxbury, NS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 183-501, Pasadena, CA 91109 USA. NR 25 TC 12 Z9 12 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD NOV 25 PY 2001 VL 106 IS E11 BP 27811 EP 27813 DI 10.1029/2000JE001425 PG 3 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 497AT UT WOS:000172431100001 ER PT J AU Hood, LL Zakharian, A Halekas, J Mitchell, DL Lin, RP Acuna, MH Binder, AB AF Hood, LL Zakharian, A Halekas, J Mitchell, DL Lin, RP Acuna, MH Binder, AB TI Initial mapping and interpretation of lunar crustal magnetic anomalies using Lunar Prospector magnetometer data SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID IMPACT BASINS; MOON; SURFACE; FIELDS; HIGHLANDS; MERCURY AB Maps of relatively strong crustal magnetic field anomalies detected at low altitudes with the magnetometer instrument on Lunar Prospector are presented. On the lunar nearside, relatively strong anomalies are mapped over the Refiner Gamma Formation on western Oceanus Procellarum and over the Rima Sirsalis rille on the southwestern border of Oceanus Procellarum. The main Rima Sirsalis anomaly does not correlate well with the rille itself but is centered over an Imbrian-aged smooth plains unit interpreted as primary or secondary basin ejecta. The stronger Refiner Gamma anomalies correlate with the locations of both the main Refiner Gamma albedo marking and its northeastward extension. Both the Rima Sirsalis and the Refiner Gamma anomalies are extended in directions approximately radial to the center of the Imbrium basin. This alignment suggests that Imbrium basin ejecta materials (lying in many cases beneath the visible mare surface) are the sources of the nearside anomalies. If so, then the albedo markings associated with the stronger Refiner Gamma anomalies may be consistent with a model involving magnetic shielding of freshly exposed mare materials from the solar wind ion bombardment. Two regions of extensive magnetic anomalies are mapped in regions centered on the Ingenii basin on the south central farside and near the crater Gerasimovic on the southeastern farside. These regions are approximately antipodal to the Imbrium and Crisium basins, respectively. The Imbrium antipode anomaly group is the most areally extensive on the Moon, while the largest anomaly in the Crisium antipode group is the strongest detected by the Lunar Prospector magnetometer. A consideration of the expected antipodal effects of basin-forming impacts as well as a combination of sample data and orbital measurements on the nearside leads to the conclusion that the most probable sources of magnetic anomalies in these two regions are ejecta materials from the respective impacts. In both regions the strongest individual anomalies correlate with swirl-like albedo markings of the Refiner Gamma class visible on available orbital photography. C1 Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Univ Arizona, Ctr Math Sci, Tucson, AZ 85721 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94729 USA. Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Lunar Res Inst, Tucson, AZ 85747 USA. RP Hood, LL (reprint author), Univ Arizona, Lunar & Planetary Lab, Kuiper Space Sci Bldg,1629 E Univ Blvd, Tucson, AZ 85721 USA. OI Halekas, Jasper/0000-0001-5258-6128 NR 38 TC 97 Z9 99 U1 1 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD NOV 25 PY 2001 VL 106 IS E11 BP 27825 EP 27839 DI 10.1029/2000JE001366 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 497AT UT WOS:000172431100004 ER PT J AU Halekas, JS Mitchell, DL Lin, RP Frey, S Hood, LL Acuna, MH Binder, AB AF Halekas, JS Mitchell, DL Lin, RP Frey, S Hood, LL Acuna, MH Binder, AB TI Mapping of crustal magnetic anomalies on the lunar near side by the Lunar Prospector electron reflectometer SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID IMPACT BASINS; MOON; MERCURY; FIELDS AB Lunar Prospector (LP) electron reflectometer measurements show that surface fields are generally weak in the large mare basalt filled impact basins on the near side but are stronger over highland terranes, especially those lying antipodal to young large impact basins. Between the Imbrium and Nectaris basins, many anomalies correlate with the Cayley and Descartes Formations. Statistical analyses show that the most strongly magnetic nearside terranes are Cayley-type light plains, terra materials, and pre-Imbrian craters. Light plains and terrae include basin impact ejecta as a major component, suggesting that magnetization effects from basin-forming impacts were involved in their formation. The magnetization of pre-Imbrian craters, however, may be evidence of early thermal remanence. Relatively strong, small-scale magnetic anomalies are present over the Refiner Gamma feature on western Oceanus Procellarum and over the Rima Sirsalis ripe on the southwestern border of Procellarum. Both Apollo subsatellite and LP data show that the latter anomaly is nearly aligned with the ripe, though LP magnetometer and reflectometer data show that the anomaly peak is actually centered over a fight plains unit. This anomaly and the Refiner Gamma anomaly are approximately radially aligned with the center of Imbrium, suggesting an association with ejecta from this basin. C1 Univ Calif Berkeley, Ctr Space Sci, Berkeley, CA 94720 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Lunar Res Inst, Tucson, AZ 85747 USA. RP Halekas, JS (reprint author), Univ Calif Berkeley, Ctr Space Sci, Berkeley, CA 94720 USA. OI Halekas, Jasper/0000-0001-5258-6128 NR 37 TC 73 Z9 75 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD NOV 25 PY 2001 VL 106 IS E11 BP 27841 EP 27852 DI 10.1029/2000JE001380 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 497AT UT WOS:000172431100005 ER PT J AU Williams, JG Boggs, DH Yoder, CF Ratcliff, JT Dickey, JO AF Williams, JG Boggs, DH Yoder, CF Ratcliff, JT Dickey, JO TI Lunar rotational dissipation in solid body and molten core SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID EARTH-MOON SYSTEM; THERMAL HISTORY; TIDAL DISSIPATION; MODEL; EVOLUTION; MANTLE; TIDES; TEMPERATURE; PROSPECTOR; LIBRATIONS AB Analyses of Lunar Laser ranges Shaw a displacement in direction of the Moon's pole of rotation which indicates that strong dissipation is acting on the rotation. Two possible sources of dissipation are monthly solid-body tides raised by the Earth (and Sun) and a fluid core with a rotation distinct from the solid body. Both effects have been introduced into a numerical integration of the lunar rotation. Theoretical consequences of tides and core on rotation and orbit are also calculated analytically. These computations indicate that the tide and core dissipation signatures are separable. They also allow unrestricted laws for tidal specific dissipation Q versus frequency to be applied. Fits of Lunar Laser ranges detect three small dissipation terms in addition to the dominant pole-displacement term. Tidal dissipation alone does not give a good match to all four amplitudes. Dissipation from tides plus fluid core accounts for them. The best match indicates a tidal Q which increases slowly with period plus a small fluid core. The core size depends on imperfectly known properties of the fluid and core-mantle interface. The radius of a core could be as much as 352 km if iron and 374 km for the Fe-FeS eutectic composition. If tidal Q versus frequency is assumed to be represented by a power law, then. the exponent is -0.19 +/- 0.13. The monthly tidal Q is 37 (-4,+6), and the annual Q is 60 (-15,+30). The power presently dissipated by solid body and core is small, but it may have been dramatic for the early Moon. The outwardly evolving Moon passed through a change of spin state which caused a burst of dissipated power in the mantle and at the core-mantle boundary. The energy deposited at the boundary plausibly drove convection in the core and temporarily powered a dynamo. The remanent magnetism in lunar rocks may result from these events, and the peak field may mark the passage of the Moon through the spin transition. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Williams, JG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 238-332, Pasadena, CA 91109 USA. NR 97 TC 169 Z9 175 U1 2 U2 18 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD NOV 25 PY 2001 VL 106 IS E11 BP 27933 EP 27968 DI 10.1029/2000JE001396 PG 36 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 497AT UT WOS:000172431100011 ER PT J AU Taylor, LA Pieters, CM Keller, LP Morris, RV McKay, DS AF Taylor, LA Pieters, CM Keller, LP Morris, RV McKay, DS TI Lunar Mare Soils: Space weathering and the major effects of surface-correlated nanophase Fe SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MOON AB Lunar soils farm the "ground truth" far calibration and modeling of reflectance spectra for quantitative remote sensing. The Lunar Soil Characterization Consortium, a group of lunar sample and remote sensing scientists, has undertaken the extensive task of characterization of lunar soils, with respect to their mineralogical and chemical makeup. This endeavor is aimed at deciphering the effects of space weathering of soils from the Moon, and these results should apply to other airless bodies. Modal abundances and chemistries of minerals and glasses in the < 45 tm size fractions of nine selected mare soils have been determined, along with the bulk chemistry of each size fractions and their I-S/FeO values: These data can be addressed at http:/web.utk.edu/similar to pgi/data.html. As grain size decreases, the bulk composition of each size fraction continuously changes and approaches the composition of the agglutinitic glasses: Past dogma had it that the majority of the nanophase Fe-0 resides in the agglutinitic glasses. However, as grain size of a soil decreases, the percentage of the total iron present as nanophase-sized Fe (0) increases dramatically, while the agglutinitic glass content rises only slightly. This is evidence for a large contribution to the I-S/FeO values from surface-correlated nanophase Fe-0, particularly in the < 10 p,m size fraction. This surficial nanophase Fe-0 is present largely as vapor-deposited patinas on the surfaces of almost every particle of the mature oils. It is proposed that these vapor-deposited, nanophase Fe-0-bearing patinas may have far greater effects upon reflectance spectra of mare soils than the agglutinitic Fe-0. C1 Univ Tennessee, Planetary Geosci Inst, Knoxville, TN 37996 USA. Brown Univ, Providence, RI 02912 USA. NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. RP Taylor, LA (reprint author), Univ Tennessee, Planetary Geosci Inst, Knoxville, TN 37996 USA. NR 47 TC 142 Z9 157 U1 5 U2 21 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD NOV 25 PY 2001 VL 106 IS E11 BP 27985 EP 27999 DI 10.1029/2000JE001402 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 497AT UT WOS:000172431100013 ER PT J AU Sang, J Follen, G Kim, C Lopez, I Townsend, S AF Sang, J Follen, G Kim, C Lopez, I Townsend, S TI Migrating legacy scientific applications towards CORBA-based client-server architectures SO SOFTWARE-PRACTICE & EXPERIENCE LA English DT Article DE client-server computing; code wrapping; CORBA; distributed object; software reusability AB A distributed object is a reusable, self-contained piece of software that cooperates with other objects on the same machine or across a network in a plug-and-play fashion via a well-defined interface. The Numerical Propulsion System Simulation (NPSS) attempts to provide a collaborative aircraft engine design and simulation environment based on this concept. Many scientific applications in aerodynamics and solid mechanics are written in Fortran. Refitting this legacy Fortran code with distributed objects can increase code reusability. In this paper, we focus on the novel use of a remote variable scheme to help programmers migrate the Fortran code towards a client-server architecture. This scheme gives the client the capability of accessing variables at the server site and makes it easier for programmers to couple component engine code. Through the operator overloading features in C++, remote variables can be used in much the same way as traditional variables. The remote variable scheme adopts the lazy update approach and the prefetch method. Preliminary performance evaluation shows that communication overhead can be greatly reduced. Copyright (C) 2001 John Wiley & Sons, Ltd. C1 Cleveland State Univ, Dept Comp & Informat Sci, Cleveland, OH 44115 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Sang, J (reprint author), Cleveland State Univ, Dept Comp & Informat Sci, 1860 E 18th St, Cleveland, OH 44114 USA. NR 32 TC 4 Z9 4 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0038-0644 J9 SOFTWARE PRACT EXPER JI Softw.-Pract. Exp. PD NOV 25 PY 2001 VL 31 IS 14 BP 1313 EP 1330 DI 10.1002/spe.415 PG 18 WC Computer Science, Software Engineering SC Computer Science GA 492XV UT WOS:000172193600001 ER PT J AU Nemani, RR White, MA Cayan, DR Jones, GV Running, SW Coughlan, JC Peterson, DL AF Nemani, RR White, MA Cayan, DR Jones, GV Running, SW Coughlan, JC Peterson, DL TI Asymmetric warming over coastal California and its impact on the premium wine industry SO CLIMATE RESEARCH LA English DT Article DE climatic change; asymmetric warming; growing season length; wine industry ID MINIMUM TEMPERATURE; CLIMATE-CHANGE; PACIFIC; TRENDS; MAXIMUM AB Climatic changes over coastal California from 1951 to 1997 may have benefited the premium wine industry, as seen in higher quality wines and larger grape yields. Observed temperature warming trends were asymmetric, with greatest warming at night and during spring. Warming was associated with large increases in eastern Pacific sea surface temperatures (SST) and amounts of atmospheric water vapor. Although the average annual temperature warming trend was modest (1.13degreesC/47 yr), there was a 20 d reduction in frost occurrence and a 65 d increase in frost-free growing season length. In the Napa and Sonoma valleys, warmer winter and spring temperatures advanced the start of the growing season by 18 to 24 d, and enhanced atmospheric water vapor resulted in a 7% reduction in evaporative demand. Given the strong coupling between Pacific SSTs and the coastal California climate, and because regional-scale SSTs persist for 6 to 12 mo, additional research may allow the possibility of predicting vintage quantity and quality from previous winter conditions. C1 Univ Montana, Numer Terradynam Simulat Grp, Missoula, MT 59812 USA. Univ Calif San Diego, Scripps Inst Oceanog, Div Climate Res, La Jolla, CA 92093 USA. US Geol Survey, Div Water Resources, La Jolla, CA 92093 USA. So Oregon Univ, Dept Geog, Ashland, OR 97520 USA. NASA, Ecosyst Sci & Technol Branch, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Nemani, RR (reprint author), Univ Montana, Numer Terradynam Simulat Grp, Missoula, MT 59812 USA. OI White, Michael/0000-0002-0238-8913 NR 33 TC 88 Z9 91 U1 3 U2 25 PU INTER-RESEARCH PI OLDENDORF LUHE PA NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY SN 0936-577X J9 CLIMATE RES JI Clim. Res. PD NOV 22 PY 2001 VL 19 IS 1 BP 25 EP 34 DI 10.3354/cr019025 PG 10 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 510RZ UT WOS:000173222200003 ER PT J AU Darve, E Pohorille, A AF Darve, E Pohorille, A TI Calculating free energies using average force SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CONSTRAINED MOLECULAR-DYNAMICS; HISTOGRAM ANALYSIS METHOD; THERMODYNAMIC INTEGRATION; POTENTIAL FUNCTIONS; SOLVENT MODEL; WATER; SIMULATIONS; MEMBRANE; EQUILIBRIUM; ALGORITHM AB A new, general formula that connects the derivatives of the free energy along the selected, generalized coordinates of the system with the instantaneous force acting on these coordinates is derived. The instantaneous force is defined as the force acting on the coordinate of interest so that when it is subtracted from the equations of motion the acceleration along this coordinate is zero. The formula applies to simulations in which the selected coordinates are either unconstrained or constrained to fixed values. It is shown that in the latter case the formula reduces to the expression previously derived by den Otter and Briels [Mol. Phys. 98, 773 (2000)]. If simulations are carried out without constraining the coordinates of interest, the formula leads to a new method for calculating the free energy changes along these coordinates. This method is tested in two examples - rotation around the C-C bond of 1,2-dichloroethane immersed in water and transfer of fluoromethane across the water-hexane interface. The calculated free energies are compared with those obtained by two commonly used methods. One of them relies on determining the probability density function of finding the system at different values of the selected coordinate and the other requires calculating the average force at discrete locations along this coordinate in a series of constrained simulations. The free energies calculated by these three methods are in excellent agreement. The relative advantages of each method are discussed. (C) 2001 American Institute of Physics. C1 Stanford Univ, Ctr Turbulence & Res, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. Univ Calif San Francisco, Dept Pharmaceut Chem, San Francisco, CA 94143 USA. RP Stanford Univ, Ctr Turbulence & Res, Stanford, CA 94305 USA. NR 41 TC 476 Z9 480 U1 8 U2 93 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-9606 EI 1089-7690 J9 J CHEM PHYS JI J. Chem. Phys. PD NOV 22 PY 2001 VL 115 IS 20 BP 9169 EP 9183 DI 10.1063/1.1410978 PG 15 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 491UW UT WOS:000172129300010 ER PT J AU Wang, JJ Keyser, LF AF Wang, JJ Keyser, LF TI Absolute rate constant of the OH plus ClO reaction at temperatures between 218 and 298 K SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID ABSORPTION CROSS-SECTIONS; RATE COEFFICIENT; BRANCHING RATIO; SELF-REACTION; KINETICS; DEPENDENCE AB The total absolute rate constant (k(1a) + k(1b)) for the reactions OH + CIO --> Cl + HO2 (k(1a)) --> HCl + O-2 (k(1b)) has been determined in the temperature range from 218 to 298 K at a total pressure of I Torr of helium. Pseudo-first-order conditions were used with ClO in large excess over initial OH. CIO was produced by reacting Cl atoms with an excess Of O-3; both CIO and O-3 were quantitatively determined by UV spectrophotometry between 210 and 310 run. Two sources of OH were used: the reaction of F atoms with excess water vapor and the reaction of H atoms with an excess of NO2. OH was monitored by resonance fluorescence near 308 nm. The absolute rate constant was determined from plots of In [OH] vs time and absolute CIO concentrations. At 298 K, the result is (2.22 +/- 0.33) x 10(-11) cm(3) molecule(-1) s(-1). The temperature dependence expressed in Arrhenius form is (7.2 +/- 2.2) x 10(-12) exp[(333 +/- 70)/T] cm(3) molecule(-1) s(-1). The uncertainties are at the 95% confidence limits and include statistical errors from the data analysis and estimates of systematic experimental errors. Numerical simulations show that under the experimental conditions used secondary reactions did not interfere with the measurements. Numerical simulations and experimental checks also show negligible loss of CIO between the time when it is determined by UV absorption and the start of the OH + CIO reaction. C1 CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. RP Keyser, LF (reprint author), CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. NR 24 TC 6 Z9 6 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD NOV 22 PY 2001 VL 105 IS 46 BP 10544 EP 10552 DI 10.1021/jp012426l PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 497QA UT WOS:000172465900007 ER PT J AU Barstow, MA Holberg, JB Hubeny, I Good, SA Levan, AJ Meru, F AF Barstow, MA Holberg, JB Hubeny, I Good, SA Levan, AJ Meru, F TI A comparison of DA white dwarf temperatures and gravities from Lyman and Balmer line studies SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE stars : atmospheres; white dwarfs; ultraviolet : stars ID HOPKINS ULTRAVIOLET TELESCOPE; STARK-BROADENING TABLES; MASS-DISTRIBUTION; EXPLORER SURVEY; HEAVY-ELEMENTS; G191-B2B; SPECTROGRAPH; CALIBRATION; PARAMETERS; HYDROGEN AB We present measurements of the effective temperatures and surface gravities for a sample of hot DA white dwarfs, using the Lyman line data available from the HUT ORFEUS and FUSE FUV space missions. Comparing the results with those from the standard Balmer line technique, we find that there is a general good overall agreement between the two methods. However, significant differences are found for a number of stars, but not always of a consistent nature in that sometimes the Balmer temperature exceeds that derived from the Lyman lines and in other instances it is lower. We conclude that, with the latest model atmosphere calculations, these discrepancies probably do not arise from an inadequate theoretical treatment of the Lyman lines but rather from systematic effects in the observation and data reduction processes, which dominate the statistical errors in these spectra. If these systematic data reduction effects can be adequately controlled, the Lyman line temperature and gravity measurements are consistent with those obtained from the Balmer lines when allowance is made for reasonable observational uncertainties. C1 Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20711 USA. Nottingham High Sch Girls, Nottingham NG1 4JB, England. RP Univ Leicester, Dept Phys & Astron, Univ Rd, Leicester LE1 7RH, Leics, England. EM mab@star.le.ac.uk NR 36 TC 19 Z9 19 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0035-8711 EI 1365-2966 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD NOV 21 PY 2001 VL 328 IS 1 BP 211 EP 222 DI 10.1046/j.1365-8711.2001.04855.x PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 497ZG UT WOS:000172484900022 ER PT J AU Silva, EDE Anthony, P Arnold, R Arrighi, H Bloom, E Baughman, B Bogart, J Bosted, P Bumala, B Chekhtman, A Cotton, N Crider, A Dobbs-Dixon, I Djannati-Atai, A Dubois, R Engovatov, D Espigat, P Evans, JL Fieguth, T Flath, D Frigaard, M Giebels, B Gillespie, S Godfrey, G Grove, JE Handa, T Hansl-Kozanecka, T Hernando, J Hicks, M Hirayama, M Johnson, WN Johnson, R Kamae, T Kroeger, W Lauben, D Lin, YC Lindner, T Michelson, P Moiseev, A Nikolaou, M Nolan, P Odian, A Ohsugi, T Ormes, J Paliaga, G Parkinson, PS Phlips, B Ritz, S Rock, S Russel, JJ Sadrozinski, H Schalk, T Silvis, J Szalata, Z Terrier, R Thompson, DJ Tournear, DM Waite, AP Wallace, J Williams, S Williamson, R Winker, G AF Silva, EDE Anthony, P Arnold, R Arrighi, H Bloom, E Baughman, B Bogart, J Bosted, P Bumala, B Chekhtman, A Cotton, N Crider, A Dobbs-Dixon, I Djannati-Atai, A Dubois, R Engovatov, D Espigat, P Evans, JL Fieguth, T Flath, D Frigaard, M Giebels, B Gillespie, S Godfrey, G Grove, JE Handa, T Hansl-Kozanecka, T Hernando, J Hicks, M Hirayama, M Johnson, WN Johnson, R Kamae, T Kroeger, W Lauben, D Lin, YC Lindner, T Michelson, P Moiseev, A Nikolaou, M Nolan, P Odian, A Ohsugi, T Ormes, J Paliaga, G Parkinson, PS Phlips, B Ritz, S Rock, S Russel, JJ Sadrozinski, H Schalk, T Silvis, J Szalata, Z Terrier, R Thompson, DJ Tournear, DM Waite, AP Wallace, J Williams, S Williamson, R Winker, G TI Results from the beam test of the engineering model of the GLAST large area telescope SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article DE silicon microstrip detectors; space; gamma-ray AB This paper describes the results of a beam test using the Engineering Model of the GLAST Large Area Telescope, which was installed in a beam of positrons, hadrons and tagged photons at SLAC. The performance of the four subsystems, Anti Coincidence Detector, Silicon Tracker, Calorimeter and Data Acquisition will be described. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Stanford Linear Accelerator Ctr, Menlo Pk, CA 94025 USA. Univ Massachusetts, Amherst, MA 01003 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Santa Cruz, SCIPP, Santa Cruz, CA 95064 USA. Stanford Univ, Stanford, CA 94305 USA. Coll France, PCC, F-75231 Paris 05, France. USN, Res Lab, Washington, DC 20375 USA. Univ Washington, Seattle, WA 98195 USA. Ctr Etud Saclay, DAPNIA, DSM, CEA, Gif Sur Yvette, France. Hiroshima Univ, Dept Phys, Hiroshima 739, Japan. Royal Inst Technol, Dept Phys, SE-10044 Stockholm, Sweden. RP Silva, EDE (reprint author), Stanford Linear Accelerator Ctr, 2575 Sand Hill Rd, Menlo Pk, CA 94025 USA. RI Nolan, Patrick/A-5582-2009; Thompson, David/D-2939-2012; Johnson, Neil/G-3309-2014; Hernando Morata, Jose Angel/L-7642-2014; OI Thompson, David/0000-0001-5217-9135; Hernando Morata, Jose Angel/0000-0002-8683-5142; Dobbs-Dixon, Ian/0000-0002-4989-6501 NR 15 TC 21 Z9 21 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD NOV 21 PY 2001 VL 474 IS 1 BP 19 EP 37 PG 19 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 495WG UT WOS:000172362900003 ER PT J AU Meister, G Rothkirch, A Spitzer, H Bienlein, J AF Meister, G Rothkirch, A Spitzer, H Bienlein, J TI Width of the specular peak perpendicular to the principal plane for rough surfaces SO APPLIED OPTICS LA English DT Article ID LIGHT-SCATTERING; REFLECTANCE AB The bidirectional reflectance distribution function (BRDF) model developed by Torrance and Sparrow [J. Opt. Sec. Am. 57, 1105-1114 (1967)] is used to describe the specular reflection of rough surfaces. We compare this model with the BRDF measurements of four manmade surfaces with different roughnesses. The model can be used to describe the basic features of the measured BRDFs, We found that the width of the specular peak perpendicular to the principal plane decreases strongly with an increasing illumination zenith angle in the data as well as in the model. A model analysis shows that the width is approximately proportional to the cosine of the illumination angle theta (i), and the deviations are determined by the roughness of the surface. This relationship is accompanied by an increase in reflectance in the specular direction in the principal plane that is 1/cos theta (i) stronger than the increase for a perfectly smooth surface. (C) 2001 Optical Society of America. C1 NASA, Goddard Space Flight Ctr, Sensor Intercomparison & Merger Biol & Interdisci, Greenbelt, MD 20771 USA. Univ Hamburg, Ctr Sci & Int Secur, Inst Phys Expt, D-22761 Hamburg, Germany. RP NASA, Goddard Space Flight Ctr, Sensor Intercomparison & Merger Biol & Interdisci, Code 970-2, Greenbelt, MD 20771 USA. EM meister@simbios.gsfc.nasa.gov RI Meister, Gerhard/F-7159-2012 NR 27 TC 3 Z9 3 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD NOV 20 PY 2001 VL 40 IS 33 BP 6072 EP 6080 DI 10.1364/AO.40.006072 PG 9 WC Optics SC Optics GA 493UY UT WOS:000172242900013 PM 18364905 ER PT J AU Zheng, W Kriss, GA Wang, JX Brotherton, M Oegerle, WR Blair, WP Davidsen, AF Green, RF Hutchings, JB Kaiser, ME AF Zheng, W Kriss, GA Wang, JX Brotherton, M Oegerle, WR Blair, WP Davidsen, AF Green, RF Hutchings, JB Kaiser, ME TI Ultraviolet broad absorption features and the spectral energy distribution of the quasar PG 1351+641 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; quasars : absorption lines; quasars : individual (PG 1351+64); ultraviolet : galaxies ID FAINT OBJECT SPECTROGRAPH; ACTIVE GALACTIC NUCLEI; X-RAY PROPERTIES; STELLAR OBJECTS; LOW-REDSHIFT; LINE QUASARS; INTRINSIC ABSORPTION; EMISSION PROPERTIES; ASCA OBSERVATIONS; OPTICAL-SPECTRA AB We present a moderate-resolution (similar to 20 km s(-1)) spectrum of the mini-broad absorption line quasar (QSO) PG 1351+64 between 915 and 1180 Angstrom obtained with the Far Ultraviolet Spectroscopic Explorer AZ, (FUSE). Additional low-resolution spectra at longer wavelengths were also obtained with the Hubble Space Telescope (HST) and ground-based telescopes. Broad absorption is present on the blue wings of C III lambda 977, Ly beta, O VI lambda lambda 1032, 1038, Ly alpha, N V lambda lambda 1238, 1242, Si IV lambda lambda 1393, 1402, and C IV lambda lambda 1548, 1550. The absorption profile can be fitted with five components at velocities of similar to -780, -1049, -1629, -1833, and -3054 km s(-1) with respect to the emission-line redshift of z = 0.088. All the absorption components cover a large fraction of the continuum source, as well as the broad-line region. The O VI emission feature is very weak, and the O VI/Ly alpha flux ratio is 0.08, one of the lowest among low-redshift active galaxies and QSOs. The UV continuum shows a significant change in slope near 1050 Angstrom in the AZ rest frame. The steeper continuum shortward of the Lyman limit extrapolates well to the observed weak X-ray flux level. The absorbers' properties are similar to those of high-redshift broad absorption line QSOs. The derived total column density of the UV absorbers is on the order of 10(21) cm(-2), unlikely to produce significant opacity above 1 keV in the X-ray. Unless there is a separate, high-ionization X-ray absorber, the QSO's weak X-ray flux may be intrinsic. The ionization level of the absorbing components is comparable to that anticipated in the broad-line region; therefore, the absorbers may be related to broad-line clouds along the line of sight. C1 Johns Hopkins Univ, Ctr Astrophys Sci, Dept Phys & Astron, Baltimore, MD 21218 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Sci & Technol China, Ctr Astrophys, Hefei 230026, Anhui, Peoples R China. Kitt Peak Natl Observ, Natl Opt Astron Observ, Tucson, AZ 85726 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V9E 2E7, Canada. RP Zheng, W (reprint author), Johns Hopkins Univ, Ctr Astrophys Sci, Dept Phys & Astron, Charles & 34th St,Bloomberg Ctr, Baltimore, MD 21218 USA. RI Oegerle, William/C-9070-2012 NR 41 TC 13 Z9 13 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP 152 EP 159 DI 10.1086/323437 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LH UT WOS:000172572300012 ER PT J AU Xu, C Lonsdale, CJ Shupe, DL O'Linger, A Masci, F AF Xu, C Lonsdale, CJ Shupe, DL O'Linger, A Masci, F TI Models for multiband infrared surveys SO ASTROPHYSICAL JOURNAL LA English DT Review DE galaxies : luminosity function, mass function; galaxies : Seyfert; galaxies : starburst; infrared : galaxies ID HUBBLE DEEP FIELD; STAR-FORMATION HISTORY; EXTRAGALACTIC SOURCE COUNTS; LARGE-SCALE STRUCTURE; AREA ISO SURVEY; MULTIWAVELENGTH ENERGY-DISTRIBUTIONS; BACKGROUND EXPERIMENT SEARCH; LOCAL LUMINOSITY FUNCTION; RADIO-CONTINUUM SURVEY; HIGH-REDSHIFT GALAXIES AB Empirical "backward" galaxy evolution models for IR bright galaxies are constrained using multiband IR surveys. A new Monte Carlo algorithm is developed for this task. It exploits a large library of realistic spectral energy distributions (SEDs) of 837 local IR galaxies (IRAS 25 mum selected) from the UV (1000 Angstrom) to the radio (20 cm), including Infrared Space Observatory (ISO) measured 3-13 mum unidentified broad features (UIBs). The basic assumption is that the local correlation between SEDs and mid-infrared (MIR) luminosities can be applied to earlier epochs of the universe, an assumption that will be strongly tested by SIRT F. By attaching an SED appropriately drawn from the SED library to every source predicted by a given model, the algorithm enables simultaneous comparisons with multiple surveys in a wide range of wave bands. Three populations of IR sources are considered in the evolution models. These include (1) starburst galaxies, (2) normal late-type galaxies, and (3) galaxies with active galactic nuclei (AGNs). Constrained by data from the literature, our best-Dt model ("peak model II) predicts that since z = 1.5 the population of starburst galaxies undergoes a very strong luminosity evolution [L = L(0)(1 + z)(4.2)] and also strong density evolution [rho = rho (0)(1 + z)(2)], the normal late-type galaxy population undergoes a passive luminosity evolution [L = L(0)(1 + z)(1.5)], and the galaxies with an AGN undergo a pure luminosity evolution similar to that of optical QSOs [L = L(0)(1 + z)(3.5)]. Prior at z greater than or equal to 1.5 all evolution rates drop as (1 + z)(-3). The luminosity evolution results in evolution of SEDs of IR bright sources because of the luminosity dependence of the SEDs. Predictions for number counts, confusion limits, redshift distributions, and color-color diagrams are made for multiband surveys using the upcoming SIRT F satellite. A Lambda cosmology (Omega (Lambda) = 0.7, Omega (m) = 0.3, H(0) = 75 km s(-1) Mpc(-1)) is assumed throughout the paper. C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. RP Xu, C (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 135 TC 82 Z9 82 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP 179 EP 207 DI 10.1086/323430 PN 1 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LH UT WOS:000172572300015 ER PT J AU Lister, ML AF Lister, ML TI Parsec-scale jet polarization properties of a complete sample of active galactic nuclei at 43 GHz SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL Lacertae objects : general; galaxies : active; galaxies : jets; polarization; quasars : general; radio continuum : galaxies ID BL-LACERTAE OBJECTS; EXTRAGALACTIC RADIO-SOURCES; OPTICAL POLARIZATION; QUASARS; EMISSION; SPECTRA; FLUX; OUTBURSTS; MODEL; SHOCK AB We present results from the highest resolution polarization imaging survey of a complete sample of extragalactic radio sources carried out to date. Our sample consists of a statistically complete flat-spectrum subset of 32 active galactic nuclei (AGNs) from the Pearson-Readhead survey, which has been studied at a variety of wavelengths and resolutions, including space-VLBI. Our observations were made with the VLBA at 43 GHz, at which the relatively higher resolution and weaker opacity effects have allowed us to probe magnetic field structures in the jets of these AGNs much closer to the central engine than in previous studies. At 43 GHz, the bulk of the total intensity and polarized emission in most flat-spectrum AGNs originates from an unresolved core component located at the extreme end of a faint jet. The luminosity of the core is positively correlated with the total source luminosity in soft X-rays, in the optical, and at 5 GHz. The most strongly polarized cores display electric vectors that are preferentially aligned with the jet axis, which is consistent with a strong transverse shock that enhances the perpendicular component of the jet magnetic field. Sources with highly polarized cores also tend to have high optical polarizations and flatter overall radio spectra. Approximately half of the AGNs in our sample display apparently bent jet morphologies that are suggestive of streaming motions along a helical path. The straightest jets in the sample tend to display slower superluminal speeds than those that are significantly bent. Our observations also show that intrinsic differences in the jet magnetic field properties of BL Lac objects and quasars previously seen on scales of tens of milliarcseconds are also present in regions much closer to the base of the jet. C1 Natl Radio Astron Observ, Charlottesville, VA 22903 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lister, ML (reprint author), Natl Radio Astron Observ, 520 Edgemont Rd, Charlottesville, VA 22903 USA. NR 35 TC 59 Z9 59 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP 208 EP 232 DI 10.1086/323522 PN 1 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LH UT WOS:000172572300016 ER PT J AU Brown, TM Sweigart, AV Lanz, T Landsman, WB Hubeny, I AF Brown, TM Sweigart, AV Lanz, T Landsman, WB Hubeny, I TI Flash mixing on the white dwarf cooling curve: Understanding hot horizontal branch anomalies in NGC 2808 SO ASTROPHYSICAL JOURNAL LA English DT Article DE globular clusters : individual (NGC 2808); stars : atmospheres; stars : evolution; stars : horizontal-branch; ultraviolet : stars ID GLOBULAR-CLUSTER NGC-2808; SPACE-TELESCOPE OBSERVATIONS; ALPHA-ELEMENT ABUNDANCES; METAL-POOR STARS; POST-AGB STARS; OMEGA-CENTAURI; NGC 2808; RADIATIVE LEVITATION; PHYSICAL PARAMETERS; VARIABLE-STARS AB We present an ultraviolet color-magnitude diagram (CMD) spanning the hot horizontal branch (HB), blue straggler, and white dwarf populations of the globular cluster NGC 2808. These data were obtained with the far-UV and near-UV cameras on the Space Telescope Imaging Spectrograph (STIS). Although previous optical CMDs of NGC 2808 show a high-temperature gap within the hot HB population, no such gap is evident in our UV CMD. Instead, we find a population of hot subluminous HB stars, an anomaly only previously reported for the globular cluster omega Cen. Our theoretical modeling indicates that the location of these subluminous stars in the UV CMD, as well as the high-temperature gap along the HB in optical CMDs, can be explained if these stars underwent a late helium-core flash while descending the white dwarf cooling curve. We show that the convection zone produced by such a late helium flash will penetrate into the hydrogen envelope, thereby mixing hydrogen into the hot helium-burning interior, where it is rapidly consumed. This phenomenon is analogous to the "born again" scenario for producing hydrogen-deficient stars following a late helium-shell flash. The flash mixing of the envelope greatly enhances the envelope helium and carbon abundances, and leads, in turn, to a discontinuous increase in the HB effective temperatures at the transition between canonical and flash-mixed stars. We argue that the hot HB gap is associated with this theoretically predicted dichotomy in the HB properties. Moreover, the changes in the emergent spectral energy distribution caused by these abundance changes are primarily responsible for explaining the hot subluminous HB stars. Although further evidence is needed to confirm that a late helium-core flash can account for the subluminous HB stars and the hot HB gap, we demonstrate that an understanding of these stars requires the use of appropriate theoretical models for their evolution, atmospheres, and spectra. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Brown, TM (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. EM tbrown@stsci.edu; sweigart@bach.gsfc.nasa.gov; lanz@nova.gsfc.nasa.gov; landsman@mpb.gsfc.nasa.gov; hubeny@tlusty.gsfc.nasa.gov NR 83 TC 133 Z9 133 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP 368 EP 393 DI 10.1086/323862 PN 1 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LH UT WOS:000172572300027 ER PT J AU Danchi, WC Tuthill, PG Monnier, JD AF Danchi, WC Tuthill, PG Monnier, JD TI Near-infrared interferometric images of the hot inner disk surrounding the massive young star MWC 349A SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; stars : individual (MWC 349A); stars : mass loss; techniques : interferometric ID HERBIG AE/BE STARS; PROTOSTELLAR DISKS; MWC-349; PHOTOEVAPORATION; EMISSION; TELESCOPE; OBJECTS; MASERS; LINES; DUST AB We present images of the massive young star MWC 349A at 1.65, 2.16, and 2.27, and 3.08 mum, reconstructed from complex visibility data obtained with an aperture-masking interferometric technique on the Keck I telescope. These images have an approximately elliptical appearance and are consistent with the expected shape of a nearly edge-on disk. Visibility data at 1.65, 2.27, and 3.08 mum were fitted with uniform ellipses with major axes 36 +/- 2, 47 +/- 2, and 62 +/- 1 mas in length, respectively. The major axis is at a position angle of 100 degrees +/- 3 degrees, consistent with the position angle of the dark lane observed previously in VLA radio continuum maps at 8 and 22 GHz. This axis is also perpendicular to the symmetry axis of the bipolar lobes of H66 alpha recombination line emission and is consistent with positions of the recombination line maser spots at 1.3 mm. At an assumed distance of 1.2 kpc, the linear sizes of the disk are 44 and 57 AU at 1.65 and 2.27 mum, respectively. These images are consistent with a dust disk having an angle between the symmetry axis of the disk and the plane of the sky of 15 degrees and thickness of 6 AU, or an angle of 20 degrees and thickness of 1.4 AU, giving an upper bound to the mass of the disk of M(d) < 5.7 or respectively. C1 NASA, Goddard Space Flight Ctr, Infrared Astrophys Branch, Greenbelt, MD 20771 USA. Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Danchi, WC (reprint author), NASA, Goddard Space Flight Ctr, Infrared Astrophys Branch, Code 685, Greenbelt, MD 20771 USA. NR 35 TC 55 Z9 55 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP 440 EP 445 DI 10.1086/323530 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LH UT WOS:000172572300032 ER PT J AU Rho, J Corcoran, MF Chu, YH Reach, WT AF Rho, J Corcoran, MF Chu, YH Reach, WT TI X-rays and protostars in the Trifid Nebula SO ASTROPHYSICAL JOURNAL LA English DT Article DE HII regions; infrared : stars; stars : formation; X-rays : individual (Trifid Nebula) ID T-TAURI STARS; ALL-SKY SURVEY; YOUNG STELLAR OBJECTS; OPHIUCHI DARK CLOUD; O-TYPE STARS; CIRCUMSTELLAR DISKS; CARINA-NEBULA; ROSAT; EMISSION; REGION AB The Trifid Nebula is a young H II region, recently rediscovered as a "pre-Orion" star-forming region, containing protostars undergoing violent mass ejections visible in optical jets as seen in images from the Infrared Space Observatory and the Hubble Space Telescope. We report the first X-ray observations of the Trifid Nebula using ROSAT and ASCA. The ROSAT image shows a dozen X-ray sources, with the brightest X-ray source being the O7 star, HD 164492, which provides most of the ionization in the nebula. We also identify 85 T Tauri star and young, massive star candidates from near-infrared colors using the JHK(s) color-color diagram from the Two-Micron All-Sky Survey (2MASS). Ten X-ray sources have counterpart near-infrared sources. The 2MASS stars and X-ray sources suggest there are potentially numerous protostars in the young H II region of the Trifid. ASCA moderate-resolution spectroscopy of the brightest source shows hard emission up to 10 keV with a clearly detected Fe K line. The best model fit is a two-temperature (T = 1.2 x 10(6) K and 39 x 10(6) K) thermal model with additional warm absorbing media. The hotter component has an unusually high temperature for either an O star or an H II region; a typical Galactic H II region could not be the primary source for such hot temperature plasma and the Fe XXV line emission. We suggest that the hotter component originates in either the interaction of the wind with another object (a companion star or a dense region of the nebula) or from flares from deeply embedded young stars. C1 CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20742 USA. Univ Illinois, Dept Astron, Urbana, IL 61801 USA. CALTECH, Space Infrared Telescope Facil Ctr, Pasadena, CA 91125 USA. RP CALTECH, Ctr Infrared Proc & Anal, MS 100-22, Pasadena, CA 91125 USA. EM rho@ipac.caltech.edu OI Reach, William/0000-0001-8362-4094 NR 55 TC 14 Z9 14 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP 446 EP 455 DI 10.1086/323053 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LH UT WOS:000172572300033 ER PT J AU Kahler, SW Reames, DV Sheeley, NR AF Kahler, SW Reames, DV Sheeley, NR TI Coronal mass ejections associated with impulsive solar energetic particle events SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : coronal mass ejections (CMEs); Sun : flares; Sun : particle emission ID X-RAY JETS; MAGNETIC RECONNECTION; PHYSICAL PARAMETERS; PLASMA EJECTIONS; WIND SPACECRAFT; FLARES; ACCELERATION; ABUNDANCES; TELESCOPE; EVOLUTION AB An impulsive solar energetic particle (SEP) event observed on the Wind spacecraft on 2000 May 1 was associated with an impulsive solar active region M1 X-ray flare. The timing and position of a fast (upsilon = 960 km s(-1)), narrow CME observed in the LASCO coronagraph on SOHO make clear the connection between the CME and the flare and SEP event. Impulsive SEP events have long been associated with impulsive flares, but only gradual SEP events have thus far been found to be associated with CMEs. A comparison of impulsive SEP events with CME observations from the Solwind and LASCO coronagraphs revealed further good cases of narrow (10 degrees -40 degrees) CMEs associated with impulsive SEP events. A recent model of impulsive flares includes jets or plasmoids that are ejected upward from magnetic reconnection sites over active regions and might therefore be expected to appear in exceptional cases as faint and narrow CMEs in coronagraphs. We suggest that this model allows us to understand better SEP production and propagation in impulsive flares. C1 USAF, Res Lab, Space Vehicles Directorate, Hanscom AFB, MA 01731 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. RP Kahler, SW (reprint author), USAF, Res Lab, Space Vehicles Directorate, Hanscom AFB, MA 01731 USA. NR 47 TC 90 Z9 92 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP 558 EP 565 DI 10.1086/323847 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LH UT WOS:000172572300044 ER PT J AU Pinfield, DJ Keenan, FP Mathioudakis, M Widing, KG Gallagher, PT Gupta, GP Tayal, S Thomas, RJ Brosius, JW AF Pinfield, DJ Keenan, FP Mathioudakis, M Widing, KG Gallagher, PT Gupta, GP Tayal, S Thomas, RJ Brosius, JW TI Electron densities in the coronae of the Sun and Procyon from extreme-ultraviolet emission line ratios in Fe XI SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; line : identification; stars : individual (Procyon, alpha Canis Minoris); Sun : corona; Sun : UV radiation ID EFFECTIVE COLLISION STRENGTHS; FINE-STRUCTURE LEVELS; IMPACT EXCITATION; SOLAR CORONA; CALIBRATION; SPECTRA; SERTS-95; IRON AB New R-matrix calculations of electron impact excitation rates for Fe XI are used to determine theoretical emission line ratios applicable to solar and stellar coronal observations. These are subsequently compared to solar spectra of the quiet Sun and an active region made by the Solar EUV Rocket Telescope and Spectrograph (SERTS-95), as well as Skylab observations of two flares. Line blending is identified, and electron densities of 10(9.3), 10(9.7), greater than or equal to 10(10.8), and greater than or equal to 10(11.3) cm(-3) are found for the quiet Sun, active region, and the two flares, respectively. Observations of the F5 IV-V star Procyon, made with the Extreme Ultraviolet Explorer (EUVE) satellite, are compared and contrasted with the solar observations. It is confirmed that Procyon's average coronal conditions are very similar to those seen in the quiet Sun, with N-e = 10(9.4) cm(-3). In addition, although the quiet Sun is the closest solar analog to Procyon, we conclude that Procyon's coronal temperatures are slightly hotter than solar. A filling factor of 25(-12)(+38)% was derived for the corona of Procyon. C1 Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. USN, Res Lab, Washington, DC 20375 USA. Computat Phys Inc, Washington, DC 20375 USA. Big Bear Solar Observ, Big Bear City, CA 92413 USA. Clark Atlanta Univ, Dept Phys, Atlanta, GA 30314 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Raytheon ITSS, Lanham, MD 20706 USA. RP Liverpool John Moores Univ, Astrophys Res Inst, 12 Quays House,Egerton Wharf, Birkenhead CH41 1LD, Merseyside, England. EM dpi@astro.livjm.ac.uk NR 31 TC 4 Z9 4 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP 566 EP 574 DI 10.1086/323465 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LH UT WOS:000172572300045 ER PT J AU Charnley, SB AF Charnley, SB TI Stochastic theory of molecule formation on dust SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; ISM : molecules; methods : numerical; methods : statistical ID SURFACE-REACTIONS; CLOUDS AB The formation of interstellar molecules on the surfaces of dust grains is calculated in the framework of stochastic reaction kinetics. The master equation and the state transition probabilities are defined, and the growth of grain mantles following accretion and reaction of gas-phase species is computed. The results are compared to the observed composition and structure of interstellar ices. The differences between this approach to gas-grain kinetics and previous work is discussed, and possible extensions of the theory are outlined. C1 NASA, Div Space Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Charnley, SB (reprint author), NASA, Div Space Sci, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. RI Charnley, Steven/C-9538-2012 NR 25 TC 56 Z9 56 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP L99 EP L102 DI 10.1086/324753 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LJ UT WOS:000172572400024 ER PT J AU Crenshaw, DM Kraemer, SB AF Crenshaw, DM Kraemer, SB TI On the nature of intrinsic absorption in reddened Seyfert 1 galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : Seyfert; ultraviolet : galaxies; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; NARROW-LINE REGION; X-RAY; DUST; CONTINUUM; EMISSION; SPECTRA AB We discuss the origin of the "dusty lukewarm absorber," which we previously identified in the reddened Seyfert 1 galaxies NGC 3227 and Akn 564. This absorber is characterized by saturated UV absorption lines (C IV, N v) near the systemic velocity of the host galaxy and is likely responsible for reddening both the continuum and emission lines (including those from the narrow-line region) from these Seyfert galaxies. From a large sample of Seyfert 1 galaxies, we find that continuum reddening (as measured by UV color) tends to increase with inclination of the host galaxy. Furthermore, reddened inclined Seyfert galaxies observed at moderate to high spectral resolution all show evidence for dusty lukewarm absorbers. We suggest that these absorbers lie in the plane of the host galaxy at distances of greater than or similar to 100 pc from the nucleus and are physically distinct from the majority of intrinsic absorbers that are outflowing from the nucleus. C1 Georgia State Univ, Dept Phys & Astron, Atlanta, GA 30303 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Catholic Univ Amer, Greenbelt, MD 20771 USA. RP Crenshaw, DM (reprint author), Georgia State Univ, Dept Phys & Astron, Atlanta, GA 30303 USA. NR 29 TC 26 Z9 26 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP L29 EP L33 DI 10.1086/337969 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LJ UT WOS:000172572400007 ER PT J AU Still, M Mukai, K AF Still, M Mukai, K TI A burst from the direction of UZ Fornacis with XMM-Newton SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : close; novae, cataclysmic variables; stars : individual (UZ Fornacis); stars : magnetic fields; white dwarfs; X-rays : binaries ID AM-HERCULIS SYSTEM; ROSAT OBSERVATIONS; RAY; EMISSION; FLARE; EXO-033319-2554.2; ACCRETION; BINARIES; FEATURES; EXCESS AB The XMM-Newton pointing toward the magnetic cataclysmic variable UZ For finds the source to be a factor of greater than 10(3) fainter than previous EXOSAT and ROSAT observations. The source was not detected for the majority of a 22 ks exposure with the European Photon Imaging Cameras, suggesting that the accretion rate either decreased or stopped altogether. However, a 1.1 ks burst was detected from UZ For during the observation. Spectral fits favor optically thin, kT = 4.4(-1.8)(+7.6) keV thermal emission. Detection of the burst by the onboard Optical Monitor indicates that this was most probably an accretion event. The 0.1-10 keV luminosity of 2.1(-0.3)(+0.6) x 10(30) ergs s(-1) is typical for accretion shock emission from high-state polars and would result from the potential energy release of similar to 10(16) g of gas. There is no significant soft excess due to reprocessing in the white dwarf atmosphere. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Univ Space Res Assoc, Columbia, MD 21044 USA. NR 30 TC 7 Z9 7 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP L71 EP L74 DI 10.1086/338103 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LJ UT WOS:000172572400017 ER PT J AU Zuckerman, B Song, I Bessell, MS Webb, RA AF Zuckerman, B Song, I Bessell, MS Webb, RA TI The beta Pictoris moving group SO ASTROPHYSICAL JOURNAL LA English DT Article DE open clusters and associations : individual (beta Pictoris); stars : kinematics; stars : pre-main-sequence ID MAIN-SEQUENCE BINARY; INTERMEDIATE-MASS STARS; X-RAY-EMISSION; ASSOCIATION; EVOLUTION; HD-35850; PLEIADES; DEBRIS; ARAE AB Following the 1983 IRAS detection and subsequent imaging of its extensive dusty circumstellar disk, beta Pictoris became the prototypical and most studied example of a potential forming planetary system. Here we report the identification of 17 star systems, each with one or more characteristics indicative of extreme youth, that are moving through space together with beta Pic. This diverse set of similar to 12 million yr old star systems, which includes a similar to 35 Jupiter mass brown dwarf, and a wide assortment of dusty circumstellar disks, is the comoving, youthful group closest to Earth. Their unique combination of youth and proximity to Earth makes group members-many of which have masses similar to that of the Sun-prime candidates for imaging of warm planets and dusty circumstellar disks with ground- and space-based telescopes. C1 Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. Australian Natl Univ, Inst Adv Studies, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Zuckerman, B (reprint author), Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. NR 37 TC 219 Z9 219 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2001 VL 562 IS 1 BP L87 EP L90 DI 10.1086/337968 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 499LJ UT WOS:000172572400021 ER PT J AU Tait, AB Barton, JS Hall, DK AF Tait, AB Barton, JS Hall, DK TI A prototype MODIS-SSM/I snow-mapping algorithm SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID COVER AB Data in the wavelength range 0.545-1.652 mum from the Moderate Resolution Imaging Spectro radiometer (MODIS), launched aboard the Earth Observing System (EOS) Terra in December 1999, are used to map daily global snow cover at 500 m resolution. However, during darkness, or when the satellite's view of the surface is obscured by cloud, snow cover cannot be mapped using MODIS data. Ve show that during these conditions, it is possible to supplement the MODIS product by mapping the snow cover using passive microwave data from the Special Sensor Microwave Imager (SSM/I), albeit with much poorer resolution. For a 7-day time period in March 1999, a prototype MODIS snow-cover product was compared with a prototype MODIS-SSM/I product for the same area in the mid-western USA. The combined MODIS-SSM/I product mapped 9% more snow cover than the MODIS-only product. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Lanham, MD 20706 USA. Gen Sci Corp, Beltsville, MD 20705 USA. RP Tait, AB (reprint author), NASA, Goddard Space Flight Ctr, Code 974, Greenbelt, MD 20771 USA. RI Hall, Dorothy/D-5562-2012 NR 27 TC 3 Z9 4 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV 20 PY 2001 VL 22 IS 17 BP 3275 EP 3284 DI 10.1080/01431160010031261 PG 10 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 490BF UT WOS:000172029800003 ER PT J AU Owe, M Van De Griend, AA AF Owe, M Van De Griend, AA TI On the relationship between thermodynamic surface temperature and high-frequency (37 GHz) vertically polarized brightness temperature under semi-arid conditions SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SOIL-MOISTURE AB A method to estimate surface temperature from high-frequency microwave observations is presented. Microwave brightness temperature is a function of the emissivity and the physical temperature of the emitting layer, and therefore possesses a strong physical basis for the estimation of surface temperature. Field observations have shown that maximum and minimum daily air temperatures are strongly related to daytime (1200 h) and night-time (2400 h) surface temperature, Field measurements of surface temperature are also compared to METEOSAT thermal observations. Long-term daily maximum and minimum air temperatures are then used to derive datasets of daytime and night-time surface temperatures. The results indicate that 37 GHz vertical polarization brightness temperature provides a reasonable estimate of spatially averaged surface temperature. This approach could provide a useful tool for climate modelling, land surface processes investigations, and other energy balance applications by providing consistent and independent long-term estimates of daily global surface temperature. C1 NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Greenbelt, MD 20771 USA. Vrije Univ Amsterdam, Fac Earth Sci, Dept Hydrol, Amsterdam, Netherlands. RP Owe, M (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Greenbelt, MD 20771 USA. NR 15 TC 41 Z9 44 U1 0 U2 8 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV 20 PY 2001 VL 22 IS 17 BP 3521 EP 3532 DI 10.1080/01431160110063788 PG 12 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 490BF UT WOS:000172029800019 ER PT J AU Delzeit, L Chen, B Cassell, A Stevens, R Nguyen, C Meyyappan, M AF Delzeit, L Chen, B Cassell, A Stevens, R Nguyen, C Meyyappan, M TI Multilayered metal catalysts for controlling the density of single-walled carbon nanotube growth SO CHEMICAL PHYSICS LETTERS LA English DT Article ID DECOMPOSITION; MODES; CO AB Ion beam sputtering has been used for the sequential deposition of metal multilayers on various substrates to control the density of single-walled carbon nanotubes (SWNTs) synthesized by chemical vapor deposition. Underlayers (10-20 nm) of Al and Ir were found to activate the substrates for SWNT growth with Fe as active catalyst. Adding Mo as cocatalyst gives increased production of SWNTs and the density can be controlled by varying the thickness of the different metal layers. High-resolution transmission electron microscopy and Raman scattering are used to characterize the SWNTs. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Eloret Corp, Sunnyvale, CA 94087 USA. RP NASA, Ames Res Ctr, MS 239-4, Moffett Field, CA 94035 USA. EM ldelzeit@mail.arc.nasa.gov NR 23 TC 162 Z9 163 U1 5 U2 67 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 EI 1873-4448 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD NOV 16 PY 2001 VL 348 IS 5-6 BP 368 EP 374 DI 10.1016/S0009-2614(01)01148-4 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 496TW UT WOS:000172413800004 ER PT J AU Dyall, KG Bauschlicher, CW Schwenke, DW Pyykko, P AF Dyall, KG Bauschlicher, CW Schwenke, DW Pyykko, P TI Is the Lamb shift chemically significant? SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GAUSSIAN-BASIS SETS; CORRELATED MOLECULAR CALCULATIONS; ATOMIZATION ENERGIES; ATOMS; THERMOCHEMISTRY; CONVERGENCE AB The contribution of the Lamb shift to the atomization energies of some prototype molecules, BF3, AlF3, and GaF3 is estimated by a perturbation procedure. It is found to be in the range 3-5% of the one-electron scalar relativistic contribution to the atomization energy. The maximum absolute value is 0.2 kcal/mol for GaF3. These sample calculations indicate that the Lamb shift is probably small enough to be neglected for energetics of molecules containing light atoms if the target accuracy is 1 kcal/mol, but for higher accuracy calculations and for molecules containing heavy elements it must be considered. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Eloret Corp, Sunnyvale, CA 94087 USA. NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Computat Chem Branch, Moffett Field, CA 94035 USA. Univ Helsinki, Dept Chem, FIN-00014 Helsinki, Finland. RP Dyall, KG (reprint author), Eloret Corp, 690 W Fremont Ave,Suite 8, Sunnyvale, CA 94087 USA. RI schwenke, david/I-3564-2013 NR 25 TC 15 Z9 15 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD NOV 16 PY 2001 VL 348 IS 5-6 BP 497 EP 500 DI 10.1016/S0009-2614(01)01162-9 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 496TW UT WOS:000172413800022 ER PT J AU Al-Saadi, JA Pierce, RB Fairlie, TD Kleb, MM Eckman, RS Grose, WL Natarajan, M Olson, JR AF Al-Saadi, JA Pierce, RB Fairlie, TD Kleb, MM Eckman, RS Grose, WL Natarajan, M Olson, JR TI Response of middle atmosphere chemistry and dynamics to volcanically elevated sulfate aerosol: Three-dimensional coupled model simulations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID QUASI-BIENNIAL OSCILLATION; GENERAL-CIRCULATION MODEL; HALOGEN OCCULTATION EXPERIMENT; STRATOSPHERIC OZONE; MOUNT-PINATUBO; HETEROGENEOUS REACTIONS; BROMINE CHEMISTRY; EL CHICHON; UARS DATA; TEMPERATURE AB The NASA Langley Research Center Interactive Modeling Project for Atmospheric Chemistry and Transport (IMPACT) model has been used to examine the response of the middle atmosphere to a large tropical stratospheric injection of sulfate aerosol, such as that following the June 1991 eruption of Mount Pinatubo. The influence of elevated aerosol on heterogeneous chemical processing was simulated using a three-dimensional climatology of surface area density (SAD) developed using observations made from the Halogen Occultation Experiment, Stratospheric Aerosol and Gas Experiment II, and Stratospheric Aerosol Measurement satellite instruments beginning in June 1991. Radiative effects of the elevated aerosol were represented by monthly mean zonally averaged heating perturbations obtained from a study conducted with the European Center/Hamburg (ECHAM4) general circulation model combined with an observationally derived set of aerosol parameters. Two elevated-aerosol simulations were integrated for 3 1/2 years following the volcanic injection. One simulation included only the aerosol radiative perturbation, and one simulation included both the radiative perturbation and the elevated SAD. These perturbation simulations are compared with multiple-year control simulations to isolate relative contributions of transport and heterogeneous chemical processing. Significance of modeled responses is assessed through comparison with interannual variability. Dynamical and photochemical contributions to ozone decreases are of comparable magnitude. Important stratospheric chemical/dynamical feedback effects are shown, as ozone reductions modulate aerosol-induced heating by up to 10% in the lower stratosphere and 25% in the middle stratosphere. Dynamically induced changes in chemical constituents which propagate into the upper stratosphere are still pronounced at the end of the simulations. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, MS 410B, Hampton, VA 23681 USA. EM j.a.al-saadi@larc.nasa.gov RI Pierce, Robert Bradley/F-5609-2010 OI Pierce, Robert Bradley/0000-0002-2767-1643 NR 59 TC 15 Z9 15 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 16 PY 2001 VL 106 IS D21 BP 27255 EP 27275 DI 10.1029/2000JD000185 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 494XZ UT WOS:000172312300003 ER PT J AU Olsen, MA Stanford, JL AF Olsen, MA Stanford, JL TI Evidence of stratosphere-to-troposphere transport within a mesoscale model and Total Ozone Mapping Spectrometer total ozone SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID POTENTIAL VORTICITY; MASS-EXCHANGE; CYCLONE AB We present evidence for stratospheric mass transport into, and remaining in, the troposphere in an intense midlatitude cyclone. Mesoscale forecast model analysis fields from the Mesoscale Analysis and Prediction System were compared with total ozone observations from the Total Ozone Measurement Spectrometer. Coupled with parcel back trajectory calculations, the analyses suggest that two mechanisms contributed to the mass exchange: (1) A region of dynamically induced exchange occurred on the cyclone's southern edge. Parcels originally in the stratosphere crossed the jet core and experienced dilution by turbulent mixing with tropospheric air. (2) Diabatic effects reduced parcel potential vorticity (PV) for trajectories traversing precipitation regions, resulting in a "PV hole" signature in the cyclone center. Air with values of ozone and water vapor typical of the lower stratosphere was left in the troposphere. The strength of the latter process may be atypical. These results, combined with other research, suggest that precipitation-induced diabatic effects can significantly modify (either decreasing or increasing) parcel potential vorticity, depending on parcel trajectory configuration with respect to jet core and maximum heating regions. The diabatic heating effect on stratosphere-troposphere exchange (STE) is more important to tropopause erosion than to altering parcel trajectories. In addition, these results underscore the importance of using not only PV but also chemical constituents for diagnoses of STE. C1 Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA. RP NASA, Goddard Space Flight Ctr, Mailstop 916-0, Greenbelt, MD 20771 USA. EM olsen@code916.gsfc.nasa.gov; stanford@iastate.edu NR 24 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 16 PY 2001 VL 106 IS D21 BP 27323 EP 27334 DI 10.1029/2001JD900202 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 494XZ UT WOS:000172312300008 ER PT J AU Rind, D deMenocal, P Russell, G Sheth, S Collins, D Schmidt, G Teller, J AF Rind, D deMenocal, P Russell, G Sheth, S Collins, D Schmidt, G Teller, J TI Effects of glacial meltwater in the GISS coupled atmosphere ocean model - 1. North Atlantic Deep Water response SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LAURENTIDE ICE-SHEET; ABRUPT CLIMATE-CHANGE; YOUNGER DRYAS EVENT; THERMOHALINE CIRCULATION; LAST DEGLACIATION; DANSGAARD-OESCHGER; HEINRICH EVENTS; TEMPERATURE; HOLOCENE; RECORDS AB Varying magnitudes of freshwater input through the St. Lawrence are added to different versions of the GISS coupled atmosphere-ocean model. The results show a generally linear response in percentage North Atlantic Deep Water (NADW) reduction to the volume of water added without any obvious threshold effects. When the estimated best guess freshwater input for the Allerod-Younger Dryas interval is added, only small reductions in NADW production occur in less than a century, with complete cessation requiring more than 300 years. If the ocean circulation was weaker in the Allerod preceding the Younger Dryas, somewhat larger percentage reductions occur, and it would take 150-200 years for a complete shutdown. The freshening is aided by a positive feedback associated with the reduction in evaporation relative to precipitation in the North Atlantic, amounting to some 20-30% of the added freshwater runoff. When the freshwater input is stopped after complete NADW shutdown, NADW production does not resume. With complete NADW cessation, cooling eventually occurs throughout the Northern Hemisphere, including regions where it is not thought to have arisen during the Younger Dryas, and the globe cools by 1 degreesC due primarily to the sea ice albedo feedback; while in many regions the observed cooling is reproduced, the cooling in Greenland is much less than is estimated. With only 50% NADW cessation, cooling is primarily around the North Atlantic, No rapid warming is seen in response to freshwater cessation. The sensitivity displayed here for NADW reduction due to freshwater input from the St. Lawrence is roughly similar to that associated with increased precipitation accompanying global warming in the next century, so a similar sensitivity may arise with Younger Dryas freshwater inputs from other suspected locations (Greenland, Europe). C1 Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Columbia Univ, NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM drind@giss.nasa.gov RI Schmidt, Gavin/D-4427-2012; demenocal, peter/B-1386-2013 OI Schmidt, Gavin/0000-0002-2258-0486; demenocal, peter/0000-0002-7191-717X NR 53 TC 57 Z9 60 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 16 PY 2001 VL 106 IS D21 BP 27335 EP 27353 DI 10.1029/2000JD000070 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 494XZ UT WOS:000172312300009 ER PT J AU Rind, D Russell, G Schmidt, G Sheth, S Collins, D deMenocal, P Teller, J AF Rind, D Russell, G Schmidt, G Sheth, S Collins, D deMenocal, P Teller, J TI Effects of glacial meltwater in the GISS coupled atmosphere-ocean model - 2. A bipolar seesaw in Atlantic Deep Water production SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NORTH-ATLANTIC; CIRCULATION; RADIOCARBON; ANTARCTICA AB The relationship between the Northern Hemisphere and Southern Hemisphere deep water circulation systems is explored in experiments with gradual and impulsive freshwater input through the St. Lawrence. With sufficient freshwater volume input (50 Sv years), North Atlantic Deep Water (NADW) cessation occurs, as does substantial cooling in the Northern Hemisphere. The colder temperatures are accompanied by increased mass and sea level pressure in the Northern Hemisphere, with corresponding lower pressure in the Southern Hemisphere. The low-pressure response occurs at high southern latitudes, consistent with the Antarctic Annular Mode, the leading mode of variability in the current climate. Stronger winds, associated with this increased cyclonicity, intensify the Antarctic Circumpolar Current (ACC) with heat flux divergences in the South Atlantic and convergences and warming in the Indian Ocean. Weddell Sea Bottom Water production increases in response to the South Atlantic high-latitude cooling and sea ice growth, hence acting as a "seesaw" with the decreasing NADW, and even global Antarctic Bottom Water increases, although not as strongly. The initial "seesaw" response occurs within a few years, although it takes some 100 years to maximize due to the response time of the ACC. The South Atlantic cooling occurs approximately in phase with the North Atlantic, so the "seesaw" is not in temperature within that ocean basin; however, warming in portions of the southern Indian Ocean occurs out of phase with the Northern Hemisphere cooling. NADW does not resume of its own accord once complete cessation occurs even when freshwater input is stopped, but when increased evaporation is used to force NADW formation temporarily, Weddell Sea Bottom Water decreases accordingly. C1 Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Columbia Univ, NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM drind@giss.nasa.gov RI Schmidt, Gavin/D-4427-2012; demenocal, peter/B-1386-2013 OI Schmidt, Gavin/0000-0002-2258-0486; demenocal, peter/0000-0002-7191-717X NR 12 TC 28 Z9 30 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 16 PY 2001 VL 106 IS D21 BP 27355 EP 27365 DI 10.1029/2001JD000954 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 494XZ UT WOS:000172312300010 ER PT J AU Redemann, J Russell, PB Hamill, P AF Redemann, J Russell, PB Hamill, P TI Dependence of aerosol light absorption and single-scattering albedo on ambient relative humidity for sulfate aerosols with black carbon cores SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MID-ATLANTIC COAST; UNITED-STATES; PARTICLES; COEFFICIENTS; EXTINCTION; BRAZIL; SIZE AB Atmospheric aerosols frequently contain hygroscopic sulfate species and black carbon (soot) inclusions. In this paper we report results of a modeling study to determine the change in aerosol absorption due to increases in ambient relative humidity (RH), for three common sulfate species, assuming that the soot mass fraction is present as a single concentric core within each particle. Because of the lack of detailed knowledge about various input parameters to models describing internally mixed aerosol particle optics, we focus on results that were aimed at determining the maximum effect that particle humidification may have on aerosol light absorption. In the wavelength range from 450 to 700 nm, maximum absorption humidification factors (ratio of wet to "dry=30% RH" absorption) for single aerosol particles are found to be as large as 1.75 when the RH changes from 30 to 99.5%. Upon lesser humidification from 30 to 80% RH, absorption humidification for single particles is only as much as 1.2, even for the most favorable combination of initial ("dry") soot mass fraction and particle size. Integrated over monomodal lognormal particle size distributions. maximum absorption humidification factors range between 1.07 and 1.15 for humidification from 30 to 80% and between 1.1 and 1.35 for humidification from 30 to 95% RH for all species considered. The largest humidification factors at a wavelength of 450 nm are obtained for "dry" particle size distributions that peak at a radius of 0.05 mum, while the absorption humidification factors at 700 nm are largest for "dry" size distributions that are dominated by particles in the radius range of 0.06 to 0.08 mum. Single-scattering albedo estimates at ambient conditions are often based on absorption measurements at low RH (similar to 30%) and the assumption that aerosol absorption does not change upon humidification (i.e., absorption humidification equal to unity). Our modeling study suggests that this assumption alone can introduce absolute errors in estimates of the midvisible single-scattering albedo of up to 0.05 for realistic dry particle size distributions. Our study also indicates that this error increases with increasing wavelength. The potential errors in aerosol single-scattering albedo derived here are comparable in magnitude and in addition to uncertainties in single-scattering albedo estimates that are based on measurements of aerosol light absorption and scattering. C1 NASA, Ames Res Ctr, BAERI, Moffett Field, CA 94035 USA. San Jose State Univ, San Jose, CA 95192 USA. RP NASA, Ames Res Ctr, BAERI, MS-245-5, Moffett Field, CA 94035 USA. EM jredemann@mail.arc.nasa.gov; prussell@mail.arc.nasa.gov; hamill@sky.arc.nasa.gov NR 18 TC 49 Z9 51 U1 2 U2 18 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 16 PY 2001 VL 106 IS D21 BP 27485 EP 27495 DI 10.1029/2001JD900231 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 494XZ UT WOS:000172312300018 ER PT J AU Bond, DW Zhang, RY Tie, XX Brasseur, G Huffines, G Orville, RE Boccippio, DJ AF Bond, DW Zhang, RY Tie, XX Brasseur, G Huffines, G Orville, RE Boccippio, DJ TI NOx production by lightning over the continental United States SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERIC NITROGEN-FIXATION; NITRIC-OXIDE PRODUCTION; ELECTRICAL DISCHARGES; FLASH CHARACTERISTICS; THUNDERSTORMS; TROPOSPHERE; ENERGY; OZONE; DISTRIBUTIONS; INTRACLOUD AB The production of NOx by lightning over the contiguous United States has been evaluated by using combined ground-based and satellite lightning measurements. The lightning data from the National Lightning Detection Network (NLDN) over the period of 1995-1999, along with a ratio of intracloud (IC) to cloud-to-ground (CG) flashes derived in conjunction with satellite lightning measurements from the Optical Transient Detector (OTD), are analyzed to obtain the number of CG and IC flashes. The average annual lightning counts over the 5-year period are about 23 million for CG flashes and 55 million for IC flashes. The resulting lightning distributions are employed to calculate the production of NOx assuming a NO production rate of 6.7 x 10(26) molecules for each CG flash and 6.7 x 10(21) molecules for each IC flash. NOx production by lightning varies seasonally in accordance with the lightning distribution, with the maximum production occurring in the summer (June, July, and August) and in the Southeast. CG flashes produce more NOx than IC flashes despite fewer CG flashes by a factor of 2 or more. The geographical and seasonal production of NOx by lightning is compared to NOx emissions from other sources (i.e., from anthropogenic, soil, and biomass-burning emissions). The results indicate that regional emissions of NOx by lightning can be significant in the summertime and may play a critical role in ozone formation in the free troposphere. Our estimate of NOx emission by lightning over the United States would decrease by an order of magnitude if we use the production rates from a recent laboratory study [Wang et al., 1998] that are significantly lower than previous estimates. C1 Texas A&M Univ, Dept Atmospher Sci, College Stn, TX 77843 USA. NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35805 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. USAF, Inst Technol, Dept Engn Phys, Wright Patterson AFB, OH 45433 USA. Max Planck Inst Meteorol, Hamburg, Germany. RP Texas A&M Univ, Dept Atmospher Sci, College Stn, TX 77843 USA. EM zhang@ariel.tamu.edu RI Zhang, Renyi/A-2942-2011; Orville, Richard/G-9866-2012 OI Orville, Richard/0000-0003-0280-7169 NR 53 TC 22 Z9 23 U1 4 U2 17 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 16 PY 2001 VL 106 IS D21 BP 27701 EP 27710 DI 10.1029/2000JD000191 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 494XZ UT WOS:000172312300033 ER PT J AU Considine, DB Rosenfield, JE Fleming, EL AF Considine, DB Rosenfield, JE Fleming, EL TI An interactive model study of the influence of the Mount Pinatubo aerosol on stratospheric methane and water trends SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID HALOGEN OCCULTATION EXPERIMENT; 2-DIMENSIONAL MODEL; INTERANNUAL VARIABILITY; TEMPERATURE-DEPENDENCE; TROPICAL TROPOPAUSE; ATMOSPHERIC METHANE; OZONE DEPLETION; II MEASUREMENTS; RATE-CONSTANT; POLAR VORTEX AB We have used the Goddard Space Flight Center interactive two-dimensional model to evaluate the effects of the Mount Pinatubo volcanic aerosol cloud on subsequent trends in upper stratospheric CH4 and H2O. The effects of the aerosol cloud were included in the model photolysis, heating rate, and heterogeneous chemistry parameterizations, resulting in thermal, chemical, and dynamical responses to the aerosol forcing. The simulation used observed extinctions and surface area densities from the Stratospheric Gas and Aerosol Experiment II instrument between 1990 and 1997. Model upper stratospheric CH4 concentrations respond to a volcanically enhanced tropical vertical upwelling of up to 24%, which increases CH4 by similar to 10% in early 1992. The decay of this CH4 pulse between 1992 and 1997 produces negative upper stratospheric trends which are in better agreement with observations than a nonvolcanic simulation but are still substantially weaker than the similar to 30-40% CH4 decreases observed in the upper stratosphere by the Halogen Occultation Experiment between 1992 and 1997. Model temperature perturbations following the eruption of similar to2-3 K between 20 and 50 hPa agree well with observations in both magnitude, timing, and duration. The temperature of the model tropopause increases by similar to0.5 K and results in a substantial transfer of H2O into the stratosphere across the model tropopause. The H2O signal takes several years to propagate into the upper stratosphere, resulting in peak increases of similar to6% at the start of 1995. Middle to upper stratospheric model H2O trends between 1992 and 1997 agree better with observations than a nonvolcanic simulation, but atmospheric observations lack the strong signature of a pulse propagating from the tropical lower stratosphere as seen in the model simulation. These comparisons suggest that the aerosol from the Mount Pinatubo eruption could have contributed to the observed changes in CH4 and H2O following the eruption but was probably not the sole driver of the observed changes. C1 Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. EM dbc@atmos.umd.edu; rose@euterpe.gsfc.nasa.gov; fleming@kahuna.gsfc.nasa.gov NR 57 TC 26 Z9 31 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 16 PY 2001 VL 106 IS D21 BP 27711 EP 27727 DI 10.1029/2001JD000331 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 494XZ UT WOS:000172312300034 ER PT J AU Peltzer, G Crampe, F Rosen, P AF Peltzer, G Crampe, F Rosen, P TI The Mw 7.1, Hector Mine, California earthquake: surface rupture, surface displacement field, and fault slip solution from ERS SAR data SO COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE II FASCICULE A-SCIENCES DE LA TERRE ET DES PLANETES LA English DT Article; Proceedings Paper CT Conference on Earthquakes CY MAR 20, 2000 CL PARIS, FRANCE DE earthquake; Hector Mine; radar interferometry; geodesy; California ID APERTURE RADAR INTERFEROMETRY; LANDERS EARTHQUAKE; EARTHS SURFACE; IMAGES; DEFORMATION AB The Mw7.1, Hector Mine, California earthquake of October 16, 1999 produced a 50 km-long surface rupture, similar to 20 km east of the surface rupture of the 1992 Landers earthquake. ERS2 radar data acquired before and after the event provide geodetic measurements of two components of the co-seismic surface displacement field. (1) Interferometric processing of the data provides the range (radar line of sight) component of the displacement field with a precision of a few millimeters. (2) The sub-pixel correlation of the before and after amplitude images provides a second component of the surface displacement field, parallel to the satellite track, with a precision of similar to 20 cm. The azimuth offset map reveals a similar to 50 km long, NNW surface rupture formed of three sections: a N40 degreesW southern section following the Bullion fault, a N10 degreesW central section cutting through the Bullion Mountains, and a northern N40 degreesW section extending up to the Lavic Lake. A north-south-trending, localized gradient in the azimuth offset field suggests that the central section of the fault extends to the north at depth over a distance of similar to 10 km. The slip distribution curve constructed using the azimuth offsets has a bell shape, with a maximum of 6.5 m at the north end of the central fault section. The fault slip model derived from the inversion of the azimuth and from range displacement data indicates that 3-5.8 m of right-lateral slip occurred between the depths of 0 and 8 km along the northern and the central sections of the fault. The solution bears a down-dip component of slip of similar to2 m, west side down, along the southern part of the northern fault section. The down-dip component of slip is consistent with compression on a northeast dipping fault. (C) 2001 Academie des sciences / Editions scientifiques et medicales Elsevier SAS. C1 Univ Calif Los Angeles, Earth & Space Sci Dept, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Peltzer, G (reprint author), Univ Calif Los Angeles, Earth & Space Sci Dept, Los Angeles, CA 90095 USA. NR 21 TC 16 Z9 16 U1 0 U2 3 PU EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER PI PARIS CEDEX 15 PA 23 RUE LINOIS, 75724 PARIS CEDEX 15, FRANCE SN 1251-8050 J9 CR ACAD SCI II A JI Comptes Rendus Acad. Sci. Ser II-A PD NOV 15 PY 2001 VL 333 IS 9 BP 545 EP 555 DI 10.1016/S1251-8050(01)01658-5 PG 11 WC Geosciences, Multidisciplinary SC Geology GA 505DV UT WOS:000172897000006 ER PT J AU Smith, EJ Balogh, A Forsyth, RJ McComas, DJ AF Smith, EJ Balogh, A Forsyth, RJ McComas, DJ TI Ulysses in the south polar cap at solar maximum: Heliospheric magnetic field SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Observations during the recent ascent of Ulysses to the south polar region are reported. Large variations in field magnitude are associated principally with solar wind interaction regions. The observed spiral angle agrees reasonably well with the Parker model. The magnetic flux, the product of the radial field component and the square of the radial distance (r(2) B-R), is independent of latitude implying non-radial expansion of the solar wind. Two magnetic sectors are present up to a latitude of approximate to -78 degrees above which a single negative (inward) polarity is observed consistent with the polar field not yet having reversed. Crossings between sectors, extrapolated back to the sun, appear consistent with a single warped current sheet tilted slightly to the rotation axis. Field lines in the polar region passing near the cur-rent sheet originate at low latitudes. They provide access of high energy solar particles to the polar region. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London, England. SW Res Inst, San Antonio, TX USA. RP Smith, EJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 79 Z9 79 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2001 VL 28 IS 22 BP 4159 EP 4162 DI 10.1029/2001GL013471 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 490CG UT WOS:000172032400002 ER PT J AU Moldwin, MB Mayerberger, S Rassoul, HK Collier, MR Lepping, RP Slavin, JA Szabo, A AF Moldwin, MB Mayerberger, S Rassoul, HK Collier, MR Lepping, RP Slavin, JA Szabo, A TI Evidence of different magnetotail responses to small solar wind pressure pulses depending on IMF Bz polarity SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; SUDDEN IMPULSES; LOW-LATITUDE AB The response of the magnetotail to small flux rope associated pressure pulses depends on the IMF Bz polaxity. Clear and large amplitude magnetotail reverse polarity South-then-North traveling compression regions (SN TCRs) are observed when the pressure pulse is associated with the northward IMF interval of the flux rope. These tail signatures correspond to small-scale (< 10 minute duration) pulses of the solar wind dynamic pressure located in front of and within the. small-scale flux ropes. Pressure pulses associated with IMF Bz southward are either absent or give rise to smaller amplitude compressions and less systematic lobe Bz rotations. These results suggest that the orientation of the IMF Bz plays a critical role in modulating the magnetotail response to solar wind dynamic pressure pulses. C1 Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Florida Inst Technol, Dept Phys & Space Sci, Melbourne, FL 32901 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Moldwin, MB (reprint author), Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. RI Moldwin, Mark/F-8785-2011; Slavin, James/H-3170-2012; Collier, Michael/I-4864-2013; OI Moldwin, Mark/0000-0003-0954-1770; Slavin, James/0000-0002-9206-724X; Collier, Michael/0000-0001-9658-6605; Rassoul, Hamid Kyan Sam/0000-0003-0681-7276 NR 14 TC 3 Z9 3 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2001 VL 28 IS 22 BP 4163 EP 4166 DI 10.1029/2001GL013045 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 490CG UT WOS:000172032400003 ER PT J AU Armstrong, EM Vazquez-Cuervo, J AF Armstrong, EM Vazquez-Cuervo, J TI A new global satellite-based sea surface temperature climatology SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB A new approach to the generation of a global sea surface temperature (SST) climatology from satellite data is presented. This work is an extension of Casey and Cornillon [1999] who demonstrated the overall superiority of constructing a global climatology using exclusively advanced very high resolution radiometer (AVHRR) Pathfinder satellite SST data vs. blended in situ/satellite data. In this implementation, a global pentad (five day) climatology was derived from daily 9 km AVHRR Pathfinder SST data through Gaussian interpolation and averaging. Performance of this climatology with respect to the Casey 9 km pentad satellite and Reynolds 1 degrees monthly climatologies was then investigated by examining the standard deviation of the anomaly data set constructed by subtracting climatological SST observations from co-located long-term in situ SST observations. In all areas examined this new climatology, hereafter referred to as the JPL pentad climatology, demonstrated modest improvements over the other climatologies. C1 CALTECH, Jet Prop Lab, Phys Oceanog DAAC, Pasadena, CA 91109 USA. RP Armstrong, EM (reprint author), CALTECH, Jet Prop Lab, Phys Oceanog DAAC, 4800 Oak Grove Dr,MS 300-320, Pasadena, CA 91109 USA. NR 8 TC 21 Z9 21 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2001 VL 28 IS 22 BP 4199 EP 4202 DI 10.1029/2001GL013316 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 490CG UT WOS:000172032400012 ER PT J AU Sun, S Bleck, R AF Sun, S Bleck, R TI Atlantic thermohaline circulation and its response to increasing CO2 in a coupled atmosphere-ocean model SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NORTH-ATLANTIC; CLIMATE-CHANGE; COORDINATE; TEMPERATURE AB We discuss aspects of the Atlantic thermohaline circulation (THC) and its response to increased greenhouse gas concentration, using a coupled atmosphere-ocean general circulation model (AOGCM) whose oceanic component is a now hybrid-isopycnal model. Two 200-year model integrations are carried out - a control run assuming fixed atmospheric composition and a perturbation run assuming gradual doubling of CO2. We employ no flux corrections at the air-sea interface, nor do we spin up the ocean prior to coupling. The surface conditions in the control run stabilize after several decades. When doubling CO2 at the rate of 1% per year, the model responds with a 2 degreesC increase in global mean surface air temperature (SAT) after 200 years and a virtually unchanged Atlantic meridional overturning circulation. The latter is maintained by a salinity increase that counteracts the effect of global warming on the surface buoyancy. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. RP Sun, S (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Sun, Shan/H-2318-2015 NR 21 TC 18 Z9 20 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2001 VL 28 IS 22 BP 4223 EP 4226 DI 10.1029/2001GL013325 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 490CG UT WOS:000172032400018 ER PT J AU Smith, MD Pearl, JC Conrath, BJ Christensen, PR AF Smith, MD Pearl, JC Conrath, BJ Christensen, PR TI One Martian year of atmospheric observations by the Thermal Emission Spectrometer SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TES OBSERVATIONS; MARS ATMOSPHERE; DUST OPACITY; WATER-VAPOR; TEMPERATURES; AEROBRAKING AB The Mars Global Surveyor has completed one full Martian year of mapping. Infrared spectra returned by the Thermal Emission Spectrometer (TES) are very well suited for monitoring the thermal structure and the distribution of aerosols and water vapor in the Mars atmosphere. Nadir-viewing spectra allow a global picture of the state of the Mars atmosphere on a daily basis. We report here on the observed annual cycle of the latitudinal dependence of atmospheric temperature, dust aerosols, water-ice clouds, and water vapor. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. RP Smith, MD (reprint author), NASA, Goddard Space Flight Ctr, Code 693, Greenbelt, MD 20771 USA. RI Smith, Michael/C-8875-2012 NR 16 TC 58 Z9 58 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2001 VL 28 IS 22 BP 4263 EP 4266 DI 10.1029/2001GL013608 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 490CG UT WOS:000172032400028 ER PT J AU Stofan, ER Smrekar, SE Tapper, SW Guest, JE Grindrod, PM AF Stofan, ER Smrekar, SE Tapper, SW Guest, JE Grindrod, PM TI Preliminary analysis of an expanded corona database for Venus SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TECTONICS; EVOLUTION; FEATURES; ORIGIN AB We have conducted an extensive survey of the Magellan data to reassess the population of coronae. We identify a new type of coronae, here referred to as 'Type 2 coronae', having the same basic morphology as previously identified coronae (Type 1), but lacking a significant (> 50%) annulus of closely spaced fractures. 106 Type 2 coronae are included in the new database giving a total of 515 coronae on Venus. The characteristics of the expanded population of Type I coronae are similar to those of the previously described population, but the Type 2 coronae are smaller, tend to have relatively flat interiors surrounded by a topographic rim, and are more likely to be found isolated from other features. Our observations, in particular the morphology and setting of the Type 2 coronae, may provide supporting evidence for the existence of a depleted mantle layer under the venusian plains. C1 Proxemy Res, Laytonville, MD 20882 USA. UCL, Dept Geol Sci, London WC1E 6BT, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Geografx, Teignmouth TQ14 8BP, Devon, England. RP Proxemy Res, 20528 Farcropft Lane, Laytonville, MD 20882 USA. EM ellen@proxemy.com RI Grindrod, Peter/F-5819-2011 OI Grindrod, Peter/0000-0002-0934-5131 NR 23 TC 37 Z9 39 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2001 VL 28 IS 22 BP 4267 EP 4270 DI 10.1029/2001GL013307 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 490CG UT WOS:000172032400029 ER PT J AU Tobita, M Murakami, M Nakagawa, H Yarai, H Fujiwara, S Rosen, PA AF Tobita, M Murakami, M Nakagawa, H Yarai, H Fujiwara, S Rosen, PA TI 3-D surface deformation of the 2000 Usu eruption measured by matching of SAR images SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RADAR INTERFEROMETRY; EARTHQUAKE AB A subpixel level offset estimation technique was applied to SAR (Synthetic Aperture Radar) images of Usu volcano, Japan. Using RADARSAT SAR amplitude images acquired from ascending and descending orbits, we generated a map of three-dimensional displacement vectors showing ground deformation associated with criptdome formation in April, 2000. Moreover, displacement velocities and volume changes were estimated. From April 3-29, inflation was observed with vertical and horizontal displacements each exceeding 20m. During the period of major activity from April 3-5, uplift and N-S spreading velocities reached 3.3m/day and 2.7m/day, respectively, while volume change was +3.4x10(6)m(3)/day. Although this technique is less precise than other methods and is not very sensitive to local deformations, it provides several key advantages including (1) personnel are not required to enter hazardous areas, (2) it provides wide spatial coverage, and (3) it does not depend on coherence, making it more widely applicable than InSAR. C1 Geog Survey Inst, Tsukuba, Ibaraki 3050811, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Tobita, M (reprint author), Geog Survey Inst, 1 Kitasato, Tsukuba, Ibaraki 3050811, Japan. NR 8 TC 21 Z9 23 U1 1 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2001 VL 28 IS 22 BP 4291 EP 4294 DI 10.1029/2001GL013329 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 490CG UT WOS:000172032400035 ER PT J AU Zhou, JY Lau, KM AF Zhou, JY Lau, KM TI Principal modes of interannual and decadal variability of summer rainfall over South America SO INTERNATIONAL JOURNAL OF CLIMATOLOGY LA English DT Article DE decadal variability; EOF analysis; interannual variability; Lanczos filter; South America; summer monsoon; summer rainfall; SVD analysis ID SEA-SURFACE TEMPERATURE; ATLANTIC CONVERGENCE ZONE; TROPICAL ATLANTIC; NORTHEAST BRAZIL; EL-NINO; INTERDECADAL VARIABILITY; PRECIPITATION ANOMALIES; ATMOSPHERIC CIRCULATION; GENERAL-CIRCULATION; CLIMATE VARIATIONS AB Using the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) product together with the Goddard Earth Observing System (GEOS) reanalysis and the National Center for Environmental Prediction (NCEP) sea-surface temperature (SST) data, we have conducted a diagnostic study of the interannual and decadal scale variability of principal modes of summer rainfall over South America for the period 1979-1995. By filtering the annual and short ( < 12 months) time-scale variations, results of empirical orthogonal function analysis show three leading modes of rainfall variation identified with interannual, decadal and long-term variability. Together, these modes explain more than half the total variance of the filtered data. The first mode is highly correlated with El Nino-Southern Oscillation (ENSO), showing a regional rainfall anomaly pattern largely consistent with previous results. This mode captures the summer season interannual variability, not only the Northeast Brazil drought but also its connection with excessive rainfall over Southern Brazil and the Ecuador coast in El Nino years. Another distinctive feature is the strengthening of the low-level flow along the eastern foothills of the eastern Andes, signifying an enhancement of the South American summer monsoon in response to an El Nino anomaly. The decadal variation displays a meridional shift of the Inter-Tropical Convergence Zone (ITCZ), which is tied to the anomalous cross-equatorial SST gradient over the Atlantic and the eastern Pacific. Associated with this mode is a large-scale mass swing between polar regions and the mid-latitudes. Over the South Atlantic and the South Pacific, the anomalous subtropical high and the associated anomalous surface wind are dynamically consistent with the distribution of local SST anomalies, suggesting the importance of atmospheric forcing at the decadal time scale. The long-term variation shows that since 1980 there has been a decrease of rainfall from the northwest coast to the southeast subtropical region and a southwards shift of the Atlantic ITCZ, leading to increased rainfall over northern and eastern Brazil. Possible links of this mode to the observed SST warming trend over the subtropical South Atlantic and to the interdecadal SST variation over the extratropical North Atlantic are discussed. Copyright (C) 2001 Royal Meteorological Society. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Maryland, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21250 USA. RP Lau, KM (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Code 913, Greenbelt, MD 20771 USA. RI Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 56 TC 82 Z9 84 U1 1 U2 16 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0899-8418 J9 INT J CLIMATOL JI Int. J. Climatol. PD NOV 15 PY 2001 VL 21 IS 13 BP 1623 EP 1644 DI 10.1002/joc.700 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 499QC UT WOS:000172581000004 ER PT J AU Tipping, RH Brown, A Ma, Q Hartmann, JM Boulet, C Lievin, J AF Tipping, RH Brown, A Ma, Q Hartmann, JM Boulet, C Lievin, J TI Collision-induced absorption in the nu(2) fundamental band of CH4. I. Determination of the quadrupole transition moment SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID METHANE SPECTRA; TEMPERATURE; MOLECULES; GASES AB An experimental value for the quadrupole transition moment of the nu (2) fundamental band of CH4 has been determined by fitting the collision-induced enhancement spectrum of CH4 with Ar as the perturber. The observed quadrupole-induced absorption increases linearly with the Ar density, rho (Ar), and is comparable to the allowed dipole intensity due to Coriolis interaction with the nu (4) band at approximately 125 amagats. Ignoring vibration-rotation interaction and Coriolis interaction,, we equate the measured slope of the integrated intensity versus rho (Ar) to the theoretical expression for the quadrupole-induced absorption, and obtain the value parallel to <0 parallel toQ parallel to nu (2)> parallel to =0.445 ea(0)(2) for the quadrupole transition matrix element. A theoretical value <0 parallel toQ parallel to nu (2)> =0.478 ea(0)(2) has been determined by large-scale ab initio calculations and, considering both the theoretical approximations and experimental uncertainties, we regard the agreement as good, thus confirming our interpretation of the enhancement as due to the quadrupole collision-induced mechanism. (C) 2001 American Institute of Physics. C1 Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. Columbia Univ, Dept Appl Phys, New York, NY 10025 USA. NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. Univ Paris 11, CNRS, Photophys Mol Lab, F-91405 Orsay, France. Free Univ Brussels, Lab Chim Phys Mol, B-1050 Brussels, Belgium. RP Tipping, RH (reprint author), Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. NR 31 TC 10 Z9 10 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD NOV 15 PY 2001 VL 115 IS 19 BP 8852 EP 8857 DI 10.1063/1.1408915 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 489PF UT WOS:000171999600013 ER PT J AU Jacobs, GA Book, JW Perkins, HT Teague, WJ AF Jacobs, GA Book, JW Perkins, HT Teague, WJ TI Inertial oscillations in the Korea Strait SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ATMOSPHERIC PREDICTION SYSTEM; CONTINENTAL-SHELF; FORECAST MODEL; MIXED LAYER; WIND; GENERATION; HURRICANE; OCEAN; WAVES; MOTIONS AB Inertial oscillations (IO) are examined in the Korea Strait based on measurements from 13 acoustic Doppler current profilers covering the time period May 1999 through March 2000. Strong IO responses to wind stress occur during summer. A simple linear model predicts that winter wind stress is expected to generate inertial responses of the same order of magnitude as those in summer. However, the observed winter IO response is much weaker than predicted. During summer, the currents within the mixed layer and below the mixed layer are of comparable amplitude but in opposite directions. The depth at which the currents reverse directions varies throughout the year as the mixed layer deepens from about 40 m during summer to the bottom of the water column in November. During winter, the velocity structure is more uniform in depth with currents in the same direction throughout the water column. One possible explanation for these phenomena is related to the combined effect of the strait boundaries and the strong summer stratification. The stratification prevents the wind stress momentum flux from mixing downward below the thermocline and thus allows the development of a bottom current separate from the surface current. Such a velocity structure is necessary to satisfy the no-flow condition through the land boundaries. C1 Stennis Space Ctr, Res Lab, USN, Stennis Space Ctr, MS 39529 USA. RP Jacobs, GA (reprint author), Stennis Space Ctr, Res Lab, USN, Code 7323, Stennis Space Ctr, MS 39529 USA. RI Jacobs, Gregg/C-1456-2008 NR 33 TC 10 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD NOV 15 PY 2001 VL 106 IS C11 BP 26943 EP 26957 DI 10.1029/2000JC000509 PG 15 WC Oceanography SC Oceanography GA 491JM UT WOS:000172105300011 ER PT J AU Vasilkov, A Krotkov, N Herman, J McClain, C Arrigo, K Robinson, WT AF Vasilkov, A Krotkov, N Herman, J McClain, C Arrigo, K Robinson, WT TI Global mapping of underwater UV irradiances and DNA-weighted exposures using total ozone mapping spectrometer and sea-viewing wide field-of-view sensor data products SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ATMOSPHERE-OCEAN SYSTEM; ULTRAVIOLET-RADIATION; SATELLITE ESTIMATION; NATURAL-WATERS; EARTHS SURFACE; ANTARCTIC PHYTOPLANKTON; ABSORPTION-SPECTRUM; OPTICAL-PROPERTIES; YELLOW SUBSTANCE; SEAWIFS DATA AB The global stratospheric ozone layer depletion results in an increase in biologically harmful ultraviolet (UV) radiation reaching the surface and penetrating to ecologically significant depths in natural waters. Such an increase can be estimated on a global scale by combining satellite estimates of UV irradiance at the ocean surface from the Total Ozone Mapping Spectrometer (TOMS) satellite instrument with the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite ocean color measurements in the visible spectral region. In this paper we propose a model of seawater optical properties in the UV spectral region based on the case I water model in the visible range. The inputs to the model are standard monthly SeaWiFS products: chlorophyll concentration and the diffuse attenuation coefficient at 490 nm. Penetration of solar UV radiation to different depths in open ocean waters is calculated using the radiative transfer quasi-single scattering approximation (QSSA). The accuracy of the QSSA approximation in the water is tested using more accurate codes. Sensitivity studies of underwater UV irradiance to atmospheric and oceanic optical properties have shown that the main environmental parameters controlling absolute levels of UVB (280-320 nm) and DNA-weighted irradiance underwater are solar zenith angle, cloud transmittance, water optical properties, and total ozone. Monthly maps of underwater UV irradiance and DNA-weighted exposure are calculated using monthly mean SeaWiFS chlorophyll and diffuse attenuation coefficient, daily SeaWiFS cloud fraction data, and the TOMS-derived surface UV irradiance daily maps. The results include global maps of monthly average UVB irradiance and DNA-weighted daily exposures at 3 and 10 m and depths where the UVB irradiance and DNA-weighted dose rate at local noon are equal to 10% of their surface values. C1 Sci Syst Applicat Inc, Lanham, MD 20706 USA. Univ Maryland Baltimore Cty, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21228 USA. NASA, Goddard Space Flight Ctr, GEST Ctr, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, SeaWiFS Project, Greenbelt, MD 20771 USA. Stanford Univ, Dept Geophys, Stanford, CA 94305 USA. SAIC Gen Sci Co, Greenbelt, MD USA. RP Vasilkov, A (reprint author), Sci Syst Applicat Inc, 10210 Greenbelt Rd,Ste 400, Lanham, MD 20706 USA. RI Krotkov, Nickolay/E-1541-2012; OI Krotkov, Nickolay/0000-0001-6170-6750; Herman, Jay/0000-0002-9146-1632 NR 74 TC 28 Z9 28 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD NOV 15 PY 2001 VL 106 IS C11 BP 27205 EP 27219 DI 10.1029/2000JC000373 PG 15 WC Oceanography SC Oceanography GA 491JM UT WOS:000172105300027 ER PT J AU Mingo, N Yang, L Han, J AF Mingo, N Yang, L Han, J TI Current-induced forces upon atoms adsorbed on conducting carbon nanotubes SO JOURNAL OF PHYSICAL CHEMISTRY B LA English DT Article ID SCANNING TUNNELING MICROSCOPE; ALKALI-METAL CHEMISORPTION; ELECTRIC-FIELD; NOBEL LECTURE; SURFACES; ELECTROMIGRATION; SYSTEMS AB We calculate the forces acting upon species adsorbed on a single wall carbon nanotube, in the presence of electric currents. We present a self-consistent real space Green function method, which enables us to calculate the current-induced forces from an ab initio Hamiltonian. The method is applied to calculate the force on an adsorbed O atom on a (5,5) carbon nanotube, for different bias voltages and adsorption sites. For good contact regimes and biases of the order of volts, the presence of a cur-rent can affect the potential energy surfaces considerably. Implications of these effects for the induced diffusion of the species are analyzed. The dependence of the force with the nanotube radius is studied. In addition, the magnitude of inelastic electron scattering, inducing vibrational heating, and its influence on the adsorbates' drift is commented. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Eloret Corp, Sunnyvale, CA 94087 USA. RP Mingo, N (reprint author), NASA, Ames Res Ctr, T27A-1, Moffett Field, CA 94035 USA. NR 33 TC 17 Z9 17 U1 0 U2 6 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5647 J9 J PHYS CHEM B JI J. Phys. Chem. B PD NOV 15 PY 2001 VL 105 IS 45 BP 11142 EP 11147 DI 10.1021/jp011491s PG 6 WC Chemistry, Physical SC Chemistry GA 493DG UT WOS:000172206300013 ER PT J AU Andriotis, AN Menon, M Srivastava, D Froudakis, G AF Andriotis, AN Menon, M Srivastava, D Froudakis, G TI Extreme hydrogen sensitivity of the transport properties of single-wall carbon-nanotube capsules SO PHYSICAL REVIEW B LA English DT Article ID ELECTRONIC-STRUCTURE; ELECTRICAL-TRANSPORT; MOLECULAR-DYNAMICS; WIRES; CLUSTERS; BINDING; ATOMS; C-60 AB I-V characteristics of single-wall carbon nanotubes are calculated and shown to be extremely sensitive to H adsorption. Furthermore, this sensitivity manifests oscillating characteristics in both metallic and semiconducting nanotubes and can be attributed mainly to the changes in the transmission function induced by H adatoms and not to the charge transfer. The results are in good agreement with a recent experimental study of hydrogen storage in single-wall carbon nanotubes. C1 Fdn Res & Technol Hellas, Inst Elect Struct & Laser, Iraklion 71110, Crete, Greece. Univ Kentucky, Dept Phys & Astron, Lexington, KY 40506 USA. Univ Kentucky, Ctr Computat Sci, Lexington, KY 40506 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Crete, Dept Chem, Iraklion 71409, Crete, Greece. RP Andriotis, AN (reprint author), Fdn Res & Technol Hellas, Inst Elect Struct & Laser, POB 1527, Iraklion 71110, Crete, Greece. EM andriot@iesl.forth.gr; super250@pop.uky.edu; deepk@nas.nasa.gov RI Andriotis, Antonios/A-2848-2014 NR 35 TC 20 Z9 20 U1 0 U2 2 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 EI 1550-235X J9 PHYS REV B JI Phys. Rev. B PD NOV 15 PY 2001 VL 64 IS 19 AR 193401 DI 10.1103/PhysRevB.64.193401 PG 4 WC Physics, Condensed Matter SC Physics GA 494WB UT WOS:000172307900022 ER PT J AU Mingo, N Han, J AF Mingo, N Han, J TI Conductance of metallic carbon nanotubes dipped into metal SO PHYSICAL REVIEW B LA English DT Article ID SCANNING TUNNELING MICROSCOPE; CONTACT RESISTANCE AB We calculate the conductance variation of several metallic carbon nanotubes as their end is being dipped into a liquid metal electrode, where experiments have shown an achievable conductance close to 2e(2)/h. The calculated conductance for a (40,40) nanotube indicates that the current flows almost entirely through the pi mode, and not the pi* mode. The calculation also predicts that for narrower nanotubes (similar to1 nm in diameter), in a "weak coupling" regime, the saturation of both pi and pi* modes should be observable. An experiment is proposed to verify this point. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Mingo, N (reprint author), NASA, Ames Res Ctr, Mail Stop T27A-1, Moffett Field, CA 94035 USA. NR 13 TC 8 Z9 9 U1 1 U2 2 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 EI 1550-235X J9 PHYS REV B JI Phys. Rev. B PD NOV 15 PY 2001 VL 64 IS 20 AR 201401 DI 10.1103/PhysRevB.64.201401 PG 4 WC Physics, Condensed Matter SC Physics GA 497PL UT WOS:000172464600032 ER PT J AU Liu, XL Lee, C Zhou, CW Han, J AF Liu, XL Lee, C Zhou, CW Han, J TI Carbon nanotube field-effect inverters SO APPLIED PHYSICS LETTERS LA English DT Article ID SINGLE-WALL; EFFECT TRANSISTORS; QUANTUM WIRES; TRANSPORT; ROPES AB This letter presents p-type metal-oxide-semiconductor (PMOS) and complementary metal-oxide-semiconductor (CMOS) inverters based on single-walled carbon nanotube field-effect transistors. The device structures consist of carbon nanotubes grown via a chemical-vapor deposition method and contacted by two metallic source/drain electrodes. Electrical properties of both p-type (without doping) and n-type nanotube transistors with potassium doping have been measured. By utilizing a resistor as the load for a p-type nanotube field-effect transistor, a PMOS inverter is demonstrated. Furthermore, by connecting a p-type nanotube transistor and an n-type nanotube transistor, a CMOS inverter is demonstrated. Both types of inverters exhibit nice transfer characteristics at room temperature. Our work represents one step forward toward integrated circuits based on nanoelectronic devices. (C) 2001 American Institute of Physics. C1 Univ So Calif, Dept Elect Engn Electrophys, Los Angeles, CA 90089 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Zhou, CW (reprint author), Univ So Calif, Dept Elect Engn Electrophys, Los Angeles, CA 90089 USA. RI Zhou, Chongwu/F-7483-2010; 李, 府中/H-4357-2011 NR 18 TC 143 Z9 147 U1 5 U2 25 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD NOV 12 PY 2001 VL 79 IS 20 BP 3329 EP 3331 DI 10.1063/1.1417516 PG 3 WC Physics, Applied SC Physics GA 490HQ UT WOS:000172046800039 ER PT J AU Baykal, A Inam, C Alpar, MA Zand, JI Strohmayer, T AF Baykal, A Inam, C Alpar, MA Zand, JI Strohmayer, T TI The steady spin-down rate of 4U 1907+09 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; stars : neutron; X-rays : binaries; X-rays : individual : 4U 1907+09 ID X-RAY PULSARS; FREQUENCY AB Using X-ray data from the Rossi X-ray Timing Explorer, we report the pulse timing results of the accretion-powered, high-mass X-ray binary pulsar 4U 1907 + 09, covering a time-span of almost two years. We measured three new pulse periods in addition to the previously measured four pulse periods. We are able to connect pulse arrival times in phase for more than a year. The source has been spinning down almost at a constant rate, with a spin-down rate of (nu) over dot = (- 3.54 +/- 0.02) x 10(-14) Hz s(-1) for more than 15 yr. Residuals of pulse arrival times yield a very low level of random-walk noise, with a strength of similar to2 x 10(-20) rad(2) s(-3) on a time-scale of 383 d, which is 40 times lower than that of the high-mass X-ray binary pulsar Vela X-1. The noise strength is only a factor of 5 greater than that of the low-mass X-ray binary pulsar 4U 1626-67. The low level of the timing noise and the very stable spin-down rate of 4U 1907+09 make this source unique among the high-mass X-ray binary pulsars, providing another example, in addition to 4U 1626-67, of long-term quiet spin down from an accreting source. These examples show that the extended quiet spin-down episodes observed in the anomalous X-ray pulsars 1RXS J170849.0-400910 and IE 2259+586 do not necessarily imply that these sources are not accreting pulsars. C1 Middle E Tech Univ, Dept Phys, TR-06531 Ankara, Turkey. Sabanci Univ, Fac Engn & Nat Sci, TR-81474 Istanbul, Turkey. Univ Utrecht, Astron Inst, NL-3508 TC Utrecht, Netherlands. Space Res Org Netherlands, NL-3584 CA Utrecht, Netherlands. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Baykal, A (reprint author), Middle E Tech Univ, Dept Phys, TR-06531 Ankara, Turkey. NR 22 TC 17 Z9 17 U1 0 U2 3 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD NOV 11 PY 2001 VL 327 IS 4 BP 1269 EP 1272 DI 10.1046/j.1365-8711.2001.04804.x PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 495MA UT WOS:000172343900028 ER PT J AU Sembach, KR Howk, JC Savage, BD Shull, JM Oegerle, WR AF Sembach, KR Howk, JC Savage, BD Shull, JM Oegerle, WR TI Far-ultraviolet spectroscopy of the intergalactic and interstellar absorption toward 3C 273 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; Galaxy : halo; intergalactic medium; ISM : abundances; ISM : molecules; quasars : absorption lines ID HUBBLE-SPACE-TELESCOPE; HIGH-RESOLUTION SPECTROGRAPH; HIGH-VELOCITY CLOUDS; LY-ALPHA FOREST; ON-ORBIT PERFORMANCE; HIGHLY IONIZED-GAS; X-RAY OBSERVATIONS; NORTH POLAR SPUR; LINE-OF-SIGHT; GALACTIC HALO AB We present Far Ultraviolet Spectroscopic Explorer observations of the molecular, neutral atomic, weakly ionized, and highly ionized components of the interstellar and intergalactic material toward the quasar 3C 273. We identify Ly beta absorption in eight of the known intergalactic Ly alpha absorbers along the sight line with rest-frame equivalent widths W(r)(Ly alpha) greater than or similar to 50 m Angstrom. Refined estimates of the H I column densities and Doppler parameters (b) of the clouds are presented. We find a range of b b approximate to 16-46 km s(-1). We detect multiple H I lines (Ly beta -Ly theta) in the 1590 km s(-1) Virgo absorber and estimate log N(H I) = 15.85 +/- (0.10)(0.08), which is 10 times more H I than in all of the other absorbers along the sight line combined. The Doppler width of this absorber, b approximate to 16 km s(-1), implies T less than or similar to 15,000 K. We detect O VI absorption at 1015 km s(-1) at the 2-3 sigma level that may be associated with hot, X-ray-emitting gas in the Virgo Cluster. We detect weak C III and O VI absorption in the intergalactic medium at z = 0.12007; this absorber is predominantly ionized and has N(H(+))/N(H I) greater than or equal to 4000Z(-1), where Z is the metallicity. Strong Galactic interstellar O VI is present between -100 and 100 km s(-1), with an additional high-velocity wing containing about 13% of the total O VI between similar to 100 and similar to 240 km s(-1). The Galactic O VI, N V, and C IV lines have similar shapes, with roughly constant ratios across the -100 to 100 km s(-1) velocity range. The high-velocity O VI wing is not detected in other species. Much of the interstellar high ion absorption probably occurs within a highly fragmented medium within the Loop IV remnant or in the outer cavity walls of the remnant. Multiple hot gas production mechanisms are required. The broad O VI absorption wing likely traces the expulsion of hot gas out of the Galactic disk into the halo. A flux limit of 5.4 x 10(-16) ergs cm(-2) s(-1) on the amount of diffuse O VI emission present similar to3'.5 off the 3C 273 sight line combined with the observed O VI column density toward 3C 273, log N(O VI) = 14.73 +/- 0.04, implies ne less than or similar to 0.002 cm(-3) and p/k less than or similar to 11,500 cm(-3) K for an assumed temperature of 3 x 10(5) K. The elemental abundances in the neutral and weakly ionized interstellar clouds are similar to those found for other halo clouds. The warm neutral and warm ionized clouds along the sight line have similar dust-phase abundances, implying that the properties of the dust grains in the two types of clouds are similar. Interstellar H(2) absorption is present at approximate to 16 km s(-1) at a level of log N(H(2)) similar to 15.71 but does not trace the main column density concentration along the sight line observed in H I 21 cm emission. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Colorado, CASA, Boulder, CO 80309 USA. Univ Colorado, JILA, Dept Astron & Planetary Sci, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Sembach, KR (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RI Oegerle, William/C-9070-2012; Howk, Jay/D-2577-2013 NR 90 TC 74 Z9 74 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP 573 EP 599 DI 10.1086/323408 PN 1 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VT UT WOS:000172188800008 ER PT J AU Malhotra, S Kaufman, MJ Hollenbach, D Helou, G Rubin, RH Brauher, J Dale, D Lu, NY Lord, S Stacey, G Contursi, A Hunter, DA Dinerstein, H AF Malhotra, S Kaufman, MJ Hollenbach, D Helou, G Rubin, RH Brauher, J Dale, D Lu, NY Lord, S Stacey, G Contursi, A Hunter, DA Dinerstein, H TI Far-infrared spectroscopy of normal galaxies: Physical conditions in the interstellar medium SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : ISM; HII regions; ISM : atoms; ISM : general; ISM : lines and bands; radiation mechanisms : thermal ID C-II EMISSION; LONG-WAVELENGTH SPECTROMETER; PHOTODISSOCIATION REGIONS; ORION NEBULA; MOLECULAR CLOUDS; STAR-FORMATION; LINE EMISSION; ATOMIC OXYGEN; CARBON; GAS AB The most important cooling lines of the neutral interstellar medium (ISM) lie in the far-infrared (FIR). We present measurements by the Infrared Space Observatory Long Wavelength Spectrometer of seven lines from neutral and ionized ISM of 60 normal, star-forming galaxies. The galaxy sample spans a range in properties such as morphology, FIR colors (indicating dust temperature), and FIR/blue ratios (indicating star formation activity and optical depth). In two-thirds of the galaxies in this sample, the [C II] line flux is proportional to FIR dust continuum. The other one-third show a smooth decline in L-[C II]/L-FIR with increasing F-v(60 mum)/F-v(100 mum) and L-FIR/L-B, spanning a range of a factor of more than 50. Two galaxies at the warm and active extreme of the range have L-[C II]/L-FIR < 2 x 10(-4) (3 upper limit). This is due to increased positive grain charge in the warmer and more active galaxies, which leads to less efficient heating by photoelectrons from dust grains. The ratio of the two principal photodissociation region (PDR) cooling lines L-[O I]/L-[C II] shows a tight correlation with F-v(60 mum)/F-v(100 mum), indicating that both gas and dust temperatures increase together. We derive a theoretical scaling between [N II] (122 mum) and [C II] from ionized gas and use it to separate [C II] emission from neutral PDRs and ionized gas. Comparison of PDR models of Kaufman et al. with observed ratios of (1) L-[O I]/L-[C II] and L-[C II] + L-[O I]/L-FIR and (2) L-[O I]/L-FIR and F-v(60 mum)/F-v(100 mum) yields far-UV flux G(0) and gas density n. The G(0) and n values estimated from the two methods agree to better than a factor of 2 and 1.5, respectively, in more than half the sources. The derived and n correlate with each other, and increases with n as G(0) proportional to n(alpha), where alpha approximate to 1.4. We interpret this correlation as arising from Stromgren sphere scalings if much of the line and continuum luminosity arises near star-forming regions. The high values of PDR surface temperature (270-900 K) and pressure (6 x 10(4)-1.5 x 10(7) K cm(-3)) derived also support the view that a significant part of grain and gas heating in the galaxies occurs very close to star-forming regions. The differences in G(0) and n from galaxy to galaxy may be due to differences in the physical properties of the star-forming clouds. Galaxies with higher G(0) and n have larger and/or denser star-forming clouds. C1 Johns Hopkins Univ, Bloomberg Ctr, Baltimore, MD 21210 USA. San Jose State Univ, Dept Phys, San Jose, CA 95192 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. CALTECH, IPAC, Pasadena, CA 91125 USA. Lowell Observ, Flagstaff, AZ 86001 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. RP Malhotra, S (reprint author), Johns Hopkins Univ, Bloomberg Ctr, Charles & 34th St, Baltimore, MD 21210 USA. NR 70 TC 214 Z9 214 U1 0 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP 766 EP 786 DI 10.1086/323046 PN 1 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VT UT WOS:000172188800021 ER PT J AU Boezio, M Bonvicini, V Schiavon, P Vacchi, A Zampa, N Bergstrom, D Carlson, P Francke, T Grinstein, S Suffert, M Hof, M Kremer, J Menn, W Simon, M Stephens, SA Ambriola, M Bellotti, R Cafagna, F Ciacio, F Circella, M De Marzo, C Finetti, N Papini, P Piccardi, S Spillantini, P Vannuccini, E Bartalucci, S Ricci, M Casolino, M De Pascale, MP Morselli, A Picozza, P Sparvoli, R Mitchell, JW Ormes, JF Streitmatter, RE Bravar, U Stochaj, SJ AF Boezio, M Bonvicini, V Schiavon, P Vacchi, A Zampa, N Bergstrom, D Carlson, P Francke, T Grinstein, S Suffert, M Hof, M Kremer, J Menn, W Simon, M Stephens, SA Ambriola, M Bellotti, R Cafagna, F Ciacio, F Circella, M De Marzo, C Finetti, N Papini, P Piccardi, S Spillantini, P Vannuccini, E Bartalucci, S Ricci, M Casolino, M De Pascale, MP Morselli, A Picozza, P Sparvoli, R Mitchell, JW Ormes, JF Streitmatter, RE Bravar, U Stochaj, SJ TI The cosmic-ray antiproton flux between 3 and 49 GeV SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; balloons; cosmic rays; dark matter; elementary particles ID MAGNETIC SPECTROMETER; ATMOSPHERIC DEPTHS; RICH DETECTOR; ANTI-PROTONS; IN-SPACE; ANTIMATTER; RADIATION; SPECTRUM; HELIUM; CALORIMETER AB We report on a new measurement of the cosmic ray antiproton spectrum. The data were collected by the balloon-borne experiment CAPRICE98, which was flown on 1998 May 28-29 from Fort Sumner, New Mexico. The experiment used the NMSU-WiZard/CAPRICE98 balloon-borne magnet spectrometer equipped with a gas Ring Imaging Cherenkov (RICH) detector, a time-of-flight system, a tracking device consisting of drift chambers and a superconducting magnet, and a silicon-tungsten calorimeter. The RICH detector was the first ever flown capable of mass-resolving charge-one particles at energies above 5 GeV. A total of 31 antiprotons with rigidities between 4 and 50 GV at the spectrometer were identified with small backgrounds from other particles. The absolute antiproton energy spectrum was determined in the kinetic energy region at the top of the atmosphere between 3.2 and 49.1 GeV. We found that the observed antiproton spectrum and the antiproton-to-proton ratio are consistent with a pure secondary origin. However, a primary component may not be excluded. C1 Univ Trieste, Dipartimento Fis, I-34147 Trieste, Italy. Ist Nazl Fis Nucl, Sez Trieste, I-34147 Trieste, Italy. Royal Inst Technol KTH, S-10405 Stockholm, Sweden. Ctr Rech Nucl, F-67037 Strasbourg, France. Univ Siegen, D-57068 Siegen, Germany. Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India. Univ Bari, Dipartmento Fis, I-70126 Bari, Italy. Ist Nazl Fis Nucl, Sez Bari, I-70126 Bari, Italy. Univ Florence, Dipartimento Fis, I-50125 Florence, Italy. Ist Nazl Fis Nucl, Sez Firenze, I-50125 Florence, Italy. Ist Nazl Fis Nucl, Lab Nazl Frascati, I-00044 Frascati, Italy. Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy. Ist Nazl Fis Nucl, Sez Roma, I-00133 Rome, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. New Mexico State Univ, Las Cruces, NM 88003 USA. RP Boezio, M (reprint author), Univ Trieste, Dipartimento Fis, Via A Valerio 2, I-34147 Trieste, Italy. RI Morselli, Aldo/G-6769-2011; Cafagna, Francesco/A-9299-2010; Vacchi, Andrea/C-1291-2010; OI Morselli, Aldo/0000-0002-7704-9553; Cafagna, Francesco/0000-0002-7450-4784; Vacchi, Andrea/0000-0003-3855-5856; Bellotti, Roberto/0000-0003-3198-2708; casolino, marco/0000-0001-6067-5104; Sparvoli, Roberta/0000-0002-6314-6117; Picozza, Piergiorgio/0000-0002-7986-3321; Papini, Paolo/0000-0003-4718-2895; Boezio, Mirko/0000-0002-8015-2981 NR 50 TC 157 Z9 158 U1 0 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP 787 EP 799 DI 10.1086/323366 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VT UT WOS:000172188800022 ER PT J AU Lis, DC Keene, J Phillips, TG Schilke, P Werner, MW Zmuidzinas, J AF Lis, DC Keene, J Phillips, TG Schilke, P Werner, MW Zmuidzinas, J TI Atomic oxygen abundance in molecular clouds: Absorption toward Sagittarius B2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM; ISM : abundances; ISM : lines and bands ID DENSE INTERSTELLAR CLOUDS; GAS-PHASE CHEMISTRY; SPIRAL ARM CLOUDS; DARK CLOUDS; WATER-VAPOR; PHOTODISSOCIATION REGIONS; CARBON-MONOXIDE; EMISSION-LINE; IC 5146; ORION AB We have obtained high-resolution (similar to 35 km s(-1)) spectra toward the molecular cloud Sgr B2 at 63 mum, the wavelength of the ground-state fine-structure line of atomic oxygen (O I), using the ISO-LWS instrument. Four separate velocity components are seen in the deconvolved spectrum, in absorption against the dust continuum emission of Sgr B2. Three of these components, corresponding to foreground clouds, are used to study the O I content of the cool molecular gas along the line of sight. In principle, the atomic oxygen that produces a particular velocity component could exist in any, or all, of three physically distinct regions : inside a dense molecular cloud, in the UV illuminated surface layer (PDR) of a cloud, and in an atomic (H I) gas. For each of the three foreground clouds, we estimate, and subtract from the observed O I column density, the oxygen content of the H I gas, by scaling from a published high-resolution 21 cm spectrum. We find that the remaining O I column density is correlated with the observed (CO)-C-13 column density. From the slope of this correlation, an average [O I]/[(CO)-C-13] ratio of 270 +/- 120 (3 sigma) is derived, which corresponds to [O I]/[CO] approximate to 9 for a CO to (CO)-C-13 abundance ratio of 30. Assuming a (CO)-C-13 abundance of 1 x 10(-6) with respect to H nuclei, we derive an atomic oxygen abundance of 2.7 x 10(-4) in the dense gas phase, corresponding to a 15% oxygen depletion compared to the diffuse ISM in our Galactic neighborhood. The presence of multiple, spectrally resolved velocity components in the Sgr B2 absorption spectrum allows, for the first time, a direct determination of the PDR contribution to the O I column density. The PDR regions should contain O I but not (CO)-C-13, and would thus be expected to produce an offset in the O I-(CO)-C-13 correlation. Our data do not show such an offset, suggesting that within our beam O I is spatially coexistent with the molecular gas, as traced by (CO)-C-13. This may be a result of the inhomogeneous nature of the clouds. C1 CALTECH, Lab Phys 320 47, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Max Planck Inst Radioastron, D-53121 Bonn, Germany. RP CALTECH, Lab Phys 320 47, Pasadena, CA 91125 USA. EM dcl@submm.caltech.edu NR 56 TC 28 Z9 28 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP 823 EP 829 DI 10.1086/323518 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VT UT WOS:000172188800025 ER PT J AU Mukai, K Smale, AP Stahle, CK Wijnands, R AF Mukai, K Smale, AP Stahle, CK Wijnands, R TI ASCA observation of MS 1603.6+2600 (= UW Coronae Borealis): A dipping low-mass X-ray binary in the outer halo? SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : individual (MS 1603.6+2600); X-rays : stars ID GLOBULAR-CLUSTERS AB MS 1603.6+2600 is a high-latitude X-ray binary with a 111 minute orbital period, thought to be either an unusual cataclysmic variable or an unusual low-mass X-ray binary. In an ASCA observation in 1997 August, we find a burst, whose light curve suggests a type I (thermonuclear flash) origin. We also find an orbital X-ray modulation in MS 1603.6+2600, which is likely to be periodic dips, presumably due to azimuthal structure in the accretion disk. Both are consistent with this system being a normal low-mass X-ray binary harboring a neutron star, but at a great distance. We tentatively suggest that MS 1603.6+2600 is located in the outer halo of the Milky Way, perhaps associated with the globular cluster Palomar 14, 11 degrees away from MS 1603.6+2600 on the sky at an estimated distance of 73.8 kpc. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. RP Mukai, K (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 17 TC 8 Z9 8 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP 938 EP 942 DI 10.1086/323383 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VT UT WOS:000172188800036 ER PT J AU Sterling, AC Moore, RL Qiu, J Wang, HM AF Sterling, AC Moore, RL Qiu, J Wang, HM TI H alpha proxies for EIT crinkles: Further evidence for preflare "breakout"-type activity in an ejective solar eruption SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : chromosphere; Sun : corona; Sun : flares; Sun : UV radiation ID CORONAL MASS EJECTIONS; YOHKOH SXT; FLARE; PROMINENCES; EVOLUTION; TELESCOPE; MISSION; REGIONS; MODEL; SUN AB We present H alpha observations from Big Bear Solar Observatory of an eruptive flare in NOAA Active Region 8210, occurring near 22:30 UT on 1998 May 1. Previously, using the EUV Imaging Telescope (EIT) on the SOHO spacecraft, we found that a pattern of transient, localized brightenings, which we call "EIT crinkles," appears in the neighborhood of the eruption near the time of flare onset. These EIT crinkles occur at a location in the active region well separated from the sheared core magnetic fields, which is where the most intense features of the eruption are concentrated. We also previously found that high-cadence images from the Soft X-ray Telescope (SXT) on Yohkoh indicate that soft X-ray intensity enhancements in the core begin after the start of the EIT crinkles. With the H alpha data, we find remote flare brightening counterparts to the EIT crinkles. Light curves as functions of time of various areas of the active region show that several of the remote flare brightenings undergo intensity increases prior to the onset of principal brightenings in the core region, consistent with our earlier findings from EIT and SXT data. These timing relationships are consistent with the eruption onset mechanism known as the breakout model, introduced by Antiochos and colleagues, which proposes that eruptions begin with reconnection at a magnetic null high above the core region. Our observations are also consistent with other proposed mechanisms that do not involve early reconnection in the core region. As a corollary, our observations are not consistent with the so-called tether-cutting models, which say that the eruption begins with reconnection in the core. The H alpha data further show that a filament in the core region becomes activated near the time of EIT crinkle onset, but little if any of the filament actually erupts, despite the presence of a halo coronal mass ejection (CME) associated with this event. C1 NASA, George C Marshall Space Flight Ctr, Space Sci Dept SD50, Huntsville, AL 35812 USA. New Jersey Inst Technol, Big Bear Solar Observ, Big Bear City, CA 92314 USA. RP Sterling, AC (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Dept SD50, Huntsville, AL 35812 USA. NR 37 TC 41 Z9 41 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP 1116 EP 1126 DI 10.1086/323374 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VT UT WOS:000172188800050 ER PT J AU Rhodes, EJ Reiter, J Schou, J Kosovichev, AG Scherrer, PH AF Rhodes, EJ Reiter, J Schou, J Kosovichev, AG Scherrer, PH TI Observed and predicted ratios of the horizontal and vertical components of the solar p-mode velocity eigenfunctions SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : helioseismology; Sun : interior; Sun : oscillations ID MEDIUM-L PROGRAM; OSCILLATIONS; FREQUENCIES; ROTATION AB We present evidence that the observed ratios of the horizontal and vertical components of the solar intermediate-degree p-mode velocity eigenfunctions closely match theoretical predictions of these ratios. This evidence comes from estimates of the observed eigenfunction component ratios that were obtained from the fitting of the p-mode oscillation peaks in low- and intermediate-degree (l less than or equal to 200) m-averaged power spectra computed from two different 60.75 day time series of Global Oscillation Network Group (GONG) project Dopplergrams obtained in late 1996 and early 1998. These fits were carried out using a peak-fitting method in which we fitted each observed p-mode multiplet with a model profile that included both the target mode and its six nearest spatial sidelobes and which incorporated the effects of the incomplete observational time series through the convolution of the fitted profiles with the temporal window functions, which were computed using the two actual GONG observing histories. The fitted profile also included the effects of the spatial leakage of the modes of differing degrees into the target spectrum through the use of different sets of m-averaged spatial leakage matrices. In order to study the sensitivity of the estimated component ratios to the details of the computation of the m-averaged power spectra and of the image-masking schemes employed by the GONG project, we generated a total of 22 different sets of modal fits. We found that the best agreement between the predicted and inferred ratios came from the use of unweighted averaged power spectra that were computed using so-called n-averaged frequency-splitting coefficients, which had been computed by cross-correlating the 2l + 1 zonal, tesseral, and sectoral power spectra at each l over a wide range of frequencies. This comparison yielded a total of 1906 pairs of predicted c(t,theory) and fitted c(t,fit) eigenfunction component ratios. A linear regression analysis of these pairs of ratios resulted in the following regression equation: c(t,fit) = (0.0088 +/- 0.0013) +/- (0.9940 +/- 0.0044)c(t,theory). The resulting correlation coefficient was 0.9817. This agreement between the predicted and inferred ratios suggests that the predicted ratios should be used in the fitting of high-degree power spectra where the ratios cannot be inferred because of the blending together of individual modal peaks into broad ridges of power. C1 Univ So Calif, Dept Phys & Astron, SSC 300, Los Angeles, CA 90089 USA. Tech Univ Munich, Zentrum Math, D-80290 Munich, Germany. Stanford Univ, WW Hansen Expt Phys Lab, Stanford, CA 94305 USA. RP Rhodes, EJ (reprint author), CALTECH, Jet Prop Lab, Space Phys & Astrophys Res Element, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 17 Z9 17 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP 1127 EP 1143 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VT UT WOS:000172188800051 ER PT J AU Cannizzo, JK AF Cannizzo, JK TI The 2001 superoutburst of WZ Sagittae: A clue to the dynamics of accretion disks SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; stars : individual (A0620-00, WZ Sagittae) ID LOCAL SHEAR INSTABILITY; WEAKLY MAGNETIZED DISKS; DWARF NOVA OUTBURSTS; CATACLYSMIC VARIABLES; SECONDARY MAXIMA; BINARY-SYSTEMS; LIGHT CURVES; VISCOSITY; IRRADIATION; SIMULATIONS AB We examine the light curve of the 2001 July-August superoutburst of WZ Sagittae. During the decline from maximum light the locally defined decay time increases from similar to4 to similar to2 days mag(-) over the first similar to 15 days of the similar to 25 day superoutburst, as the system faded from to. The superoutburst is caused by the m(V) similar or equal to 8.5 m(V) similar or equal to 10 sudden accretion of similar to 10(24) g of gas onto the white dwarf, and the deviation from exponentiality in the decay light curve is expected qualitatively during a "viscous decay" in which the dominant mode of depletion of the gas stored in the accretion disk is accretion onto the central object. In other words, as the mass of the accretion disk decreases, the viscous timescale increases. We show that the data are also quantitatively consistent with the theoretical viscous decay time, both calculated via a simple scaling and also from time-dependent calculations, when one adopts standard model parameters for WZ Sge. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Emergent Informat Technol Inc, Greenbelt, MD 20771 USA. RP Cannizzo, JK (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Emergent Informat Technol Inc, Code 662, Greenbelt, MD 20771 USA. NR 38 TC 15 Z9 15 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP L175 EP L178 DI 10.1086/324680 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VU UT WOS:000172188900008 ER PT J AU Furusho, T Yamasaki, NY Ohashi, T Shibata, R Ezawa, H AF Furusho, T Yamasaki, NY Ohashi, T Shibata, R Ezawa, H TI Temperature map of the Perseus Cluster of galaxies observed with ASCA SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : individual (Perseus); intergalactic medium; X-rays : galaxies ID X-RAY-CLUSTERS; INTRACLUSTER MEDIUM; PSPC OBSERVATIONS; SIMULATIONS; GAS AB We present a two-dimensional temperature map of the Perseus Cluster based on multipointing observations with the ASCA Gas Imaging Spectrometer, covering a region with a diameter of similar to2 degrees. By correcting for the effect of the X-ray telescope response, the temperatures were estimated from hardness ratios, and the complete temperature structure of the cluster with a spatial resolution of about 100 kpc was obtained for the first time. There is an extended cool region with a diameter of similar to 20' and kT similar to5 about 20' east of the cluster center. This region also shows higher surface brightness and is surrounded by a large ringlike hot region with kT greater than or similar to 7 keV and is likely to be a remnant of a merger with a poor cluster. Another extended cool region is extending outward from the IC 310 subcluster. These features and the presence of several other hot and cool blobs suggest that this rich cluster has been formed as the result of a repetition of many subcluster mergers. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Tokyo Metropolitan Univ, Dept Phys, Tokyo 1920397, Japan. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. Natl Astron Observ, Nobeyama Radio Observ, Nagano 3841305, Japan. RP Furusho, T (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. RI Yamasaki, Noriko/C-2252-2008 NR 23 TC 21 Z9 21 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP L165 EP L169 DI 10.1086/324758 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VU UT WOS:000172188900006 ER PT J AU Harra, LK Sterling, AC AF Harra, LK Sterling, AC TI Material outflows from coronal intensity "dimming regions" during coronal mass ejection onset SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : coronal mass ejections (CMEs); Sun : transition region ID DIAGNOSTIC SPECTROMETER; SOLAR; SOHO; TELESCOPE; MISSION; STORMS; WAVES; FLARE; CMES AB One signature of expulsion of coronal mass ejections (CMEs) from the solar corona is the appearance of transient intensity dimmings in coronal images. These dimmings have generally been assumed to be due to discharge of CME material from the corona, and thus the "dimming regions" are thought of as an important signature of the sources of CMEs. We present spectral observations of two dimming regions at the time of expulsion of CMEs, using the Coronal Diagnostic Spectrometer (CDS) on the SOHO satellite. One of the dimming regions is at the solar limb and associated with a CME traveling in the plane of the sky, while the other region is on the solar disk and associated with an Earth-directed "halo" CME. From the limb event, we see Doppler signatures of approximate to 30 km s(-1) in coronal (Fe XVI and Mg IX) emission lines, where the enhanced velocities coincide with the locations of coronal dimming. This provides direct evidence that the dimmings are associated with outflowing material. We also see larger (approximate to 100 km s(-1)) Doppler velocities in transition region (O V and He I) emission lines, which are likely to be associated with motions of a prominence and loops at transition region temperatures. An "EIT wave" accompanies the disk event, and a dimming region behind the wave shows strong blueshifted Doppler signatures of approximate to 100 km s(-1) in O V, suggesting that material from the dimming regions behind the wave may be feeding the CME. C1 UCL, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. United Appl Technol Inc, Huntsville, AL USA. RP Harra, LK (reprint author), UCL, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England. NR 23 TC 100 Z9 103 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP L215 EP L218 DI 10.1086/324767 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VU UT WOS:000172188900018 ER PT J AU Reilly, KT Bloom, ED Focke, W Giebels, B Godfrey, G Parkinson, PMS Shabad, G Ray, PS Bandyopadhyay, RM Wood, KS Wolff, MT Fritz, GG Hertz, P Kowalski, MP Lovellette, MN Yentis, DJ Scargle, JD AF Reilly, KT Bloom, ED Focke, W Giebels, B Godfrey, G Parkinson, PMS Shabad, G Ray, PS Bandyopadhyay, RM Wood, KS Wolff, MT Fritz, GG Hertz, P Kowalski, MP Lovellette, MN Yentis, DJ Scargle, JD TI USA experiment observation of spectral and timing evolution during the 2000 outburst of XTE J1550-564 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : general; stars : individual (XTE J1550-564); X-rays : stars ID ACCRETION; DISKS AB We report on timing and spectral observations of the 2000 outburst of XTE J1550-64 made by the Unconventional Stellar Aspect (USA) experiment on board the Advanced Research and Global Observation Satellite (ARGOS). We observe a low-frequency quasi-periodic oscillation with a centroid frequency that tends to increase with increasing flux and a fractional rms amplitude that is correlated with the hardness ratio. Several high-frequency quasi-periodic oscillations were detected by Rossi X-Ray Timing Explorer during periods where the low-frequency quasi-periodic oscillation was seen to be weakening or not detectable at all. The evolution of the hardness ratio (4-16 keV/1-4 keV) with time and source flux is examined. The hardness-intensity diagram shows a cyclical movement in the counterclockwise direction and possibly indicates the presence of two independent accretion flows: a thin-disk flow and a hot sub-Keplerian flow. C1 Stanford Univ, Stanford Linear Accelerator Ctr, Stanford, CA 94309 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94305 USA. RP Reilly, KT (reprint author), Stanford Univ, Stanford Linear Accelerator Ctr, Stanford, CA 94309 USA. OI Ray, Paul/0000-0002-5297-5278 NR 22 TC 8 Z9 8 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP L183 EP L186 DI 10.1086/324756 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VU UT WOS:000172188900010 ER PT J AU Sterling, AC Moore, RL Thompson, BJ AF Sterling, AC Moore, RL Thompson, BJ TI EIT and SXT observations of a quiet-region filament ejection: First eruption, then reconnection SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : chromosphere; Sun : corona; Sun : flares; Sun : UV radiation ID CORONAL MASS EJECTIONS; FLARE; TELESCOPE; MISSION; MODEL AB We observe a slow-onset quiet-region filament eruption with the EUV Imaging Telescope (EIT) on the Solar Heliospheric Observatory (SOHO) and the soft X-ray telescope (SXT) on Yohkoh. This event occurred on 1999 April 18 and was likely the origin of a coronal mass ejection detected by SOHO at 08:30 UT on that day. In the EIT observation, one-half of the filament shows two stages of evolution: stage 1 is a slow, roughly constant upward movement at approximate to1 km s(-1) lasting approximate to6.5 hr, and stage 2 is a rapid upward eruption at approximate to 16 km s(-1) occurring just before the filament disappears into interplanetary space. The other half of the filament shows little motion along the line of sight during the time of stage 1 but erupts along with the rest of the filament during stage 2. There is no obvious emission from the filament in the SXT observation until stage 2; at that time, an arcade of EUV and soft X-ray loops forms first at the central location of the filament and then expands outward along the length of the filament channel. A plot of EUV intensity versus time of the central portion of the filament (where the postflare loops initially form) shows a flat profile during stage 1 and a rapid upturn after the start of stage 2. This light curve is delayed from what would be expected if "tether-cutting" reconnection in the core of the erupting region were responsible for the initiation of the eruption. Rather, these observations suggest that a loss of stability of the magnetic field holding the filament initiates the eruption, with reconnection in the core region occurring only as a by-product. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. United Appl Technol, Huntsville, AL USA. RP Sterling, AC (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, SD50, Huntsville, AL 35812 USA. RI Thompson, Barbara/C-9429-2012 NR 19 TC 22 Z9 22 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2001 VL 561 IS 2 BP L219 EP L222 DI 10.1086/324765 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 492VU UT WOS:000172188900019 ER PT J AU Day, MJ Mansour, NN Reynolds, WC AF Day, MJ Mansour, NN Reynolds, WC TI Nonlinear stability and structure of compressible reacting mixing layers SO JOURNAL OF FLUID MECHANICS LA English DT Article ID SHEAR LAYERS; LINEAR-STABILITY; LARGE EDDIES; TURBULENT; EQUATIONS; EVOLUTION; GROWTH AB The parabolized stability equations (PSE) are used to investigate issues of nonlinear flow development and mixing in compressible reacting shear layers, which are modelled with an infinitely fast-chemistry assumption. Particular emphasis is placed on investigating the change in flow structure that occurs when compressibility and heat release are added to the flow. These conditions allow the 'outer' instability modes-one associated with each of the fast and slow streams-to dominate over the 'central', Kelvin-Helmholtz mode that exists unaccompanied in incompressible non-reacting mixing layers. Analysis of scalar probability density functions in flows with dominant outer modes demonstrates the ineffective, one-sided nature of mixing that accompanies these flow structures. Colayer conditions, where two modes have equal growth rate and the mixing layer is formed by two sets of vortices, offer some opportunity for mixing enhancement. Their extent, however, is found to be limited in the mixing layer's parameter space. Extensive validation of the PSE technique also provides a unique perspective on central-mode vortex pairing, further supporting the view that pairing is primarily governed by instability growth rates; mutual induction appears to be a secondary process. This perspective sheds light on how linear stability theory is able to provide such an accurate prediction of experimentally observed, fully nonlinear flow phenomenon. C1 Stanford Univ, Dept Mech Engn, Stanford, CA 94035 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Day, MJ (reprint author), Stanford Univ, Dept Mech Engn, Stanford, CA 94035 USA. NR 56 TC 23 Z9 26 U1 0 U2 4 PU CAMBRIDGE UNIV PRESS PI PORT CHESTER PA 110 MIDLAND AVE, PORT CHESTER, NY 10573-9863 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD NOV 10 PY 2001 VL 446 BP 375 EP 408 PG 34 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 491AJ UT WOS:000172085600015 ER PT J AU de Viron, O Marcus, SL Dickey, JO AF de Viron, O Marcus, SL Dickey, JO TI Diurnal angular momentum budget of the atmosphere and its consequences for Earth's nutation SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID OSCILLATIONS; PRECESSION; PRESSURE; BALANCE; TORQUE AB The three-dimensional diurnal atmospheric angular momentum (AAM) budget is investigated, and its geographical features and meteorological dynamics are explored. It is shown that the diurnal atmospheric torques are associated with mass effect (ellipsoidal torque for the equatorial component and mountain torque for the axial component). It is shown that there is an important difference between the torque and angular momentum approaches on diurnal timescales, with the AAM time derivative generally exceeding the calculated torques. For the retrograde diurnal band, however, which is of interest for Earth nutation, the torque approach predicts much larger AAM changes than those observed. The AAM budget equation is also investigated theoretically, in order to give condition on the torques and AAM in order to verify the equation. Alternatively to the condition proposed by Bell, [1994], a condition on the local torque is shown sufficient to verify the AAM budget equation in the retrograde band, that is, the local torque have to balance the ellipsoidal effect. This condition is shown to be verified qualitatively. However, when separating the AAM budget equation into prograde and retrograde part, this last part become very sensitive to the error on the computation of the local torque. This explains why the torque approach always give one order of magnitude larger than the AAM approach at the retrograde diurnal frequencies. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP de Viron, O (reprint author), Observ Royal Belgique, Brussels, Belgium. EM o.deviron@oma.be; Steve.L.Marcus@jpl.nasa.gov; Jean.O.Dickey@jpl.nasa.gov RI de Viron, Olivier/N-6647-2014; OI de Viron, Olivier/0000-0003-3112-9686; Marcus, Steven/0000-0002-5763-6961 NR 17 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD NOV 10 PY 2001 VL 106 IS B11 BP 26747 EP 26759 DI 10.1029/2000JB000098 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 491CG UT WOS:000172090000026 ER PT J AU Tyuterev, VG Tashkun, SA Schwenke, DW AF Tyuterev, VG Tashkun, SA Schwenke, DW TI An accurate isotopically invariant potential function of the hydrogen sulphide molecule SO CHEMICAL PHYSICS LETTERS LA English DT Article ID ROVIBRATIONAL ENERGY-LEVELS; MU-M; INFRARED-SPECTRUM; GROUND-STATE; H-2 S-32; H2S; SULFIDE; SURFACE; WATER; INTENSITIES AB The potential function of the electronic ground state of the hydrogen sulphide molecule is obtained by the simultaneous fit of a very large sample of high-resolution vibration-rotation data. The use of an extensive set of more than 12000 experimental rovibrational transitions, corresponding to 4175 rovibrational states with J(max) = 15, K-a max = 15 for bands of 7 isotopomers ((H2S)-S-32, (H2S)-S-33, (H2S)-S-34, (D2S)-S-32, (D2S)-S-34, (HDS)-S-32, and (HDS)-S-34), allows improved calculations of 'local-mode states' and highly excited bending-rotational states. The root-mean-square (PMS) deviation of the rovibrational fit is 0.05 cm(-1). For the entire set of all 73 band centres of all isotopic species for which experimental data exists, the RMS deviation of the results of calculations with a single isotopic invariant potential function is 0.03 cm(-1). (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Reims, UFR Sci, CNRS UMR 6089, Grp Spect Mol & Atmospher, F-51687 Reims 2, France. Russian Acad Sci, Inst Atmospher Opt, Tomsk 634055, Russia. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Tyuterev, VG (reprint author), Univ Reims, UFR Sci, CNRS UMR 6089, Grp Spect Mol & Atmospher, BP 1039, F-51687 Reims 2, France. RI Tashkun, Sergey/E-8682-2014; schwenke, david/I-3564-2013 NR 34 TC 24 Z9 26 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD NOV 9 PY 2001 VL 348 IS 3-4 BP 223 EP 234 DI 10.1016/S0009-2614(01)01093-4 PG 12 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 491CF UT WOS:000172089900010 ER PT J AU Elfouhaily, T Thompson, DR Vandemark, D Chapron, B AF Elfouhaily, T Thompson, DR Vandemark, D Chapron, B TI Higher-order hydrodynamic modulation: theory and applications for ocean waves SO PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article DE nonlinear surface waves; hydrodynamic modulation; higher-order surface wave statistics; truncated Hamiltonian function ID SEA-SURFACE ROUGHNESS; SHORT GRAVITY WAVES; WIND-WAVES; STOCHASTIC-MODEL; CAPILLARY WAVES; ENERGY-TRANSFER; LONG WAVES; SPECTRUM; BACKSCATTER; CURRENTS AB Under the two-scale hydrodynamic model for ocean surface waves, short waves are modulated hydrodynamically by long waves. An exact numerical simulation of the two-scale hydrodynamic process shows that the most commonly used modulation transfer function (MTF), which is a linear approximation., does not capture all of the features caused by the inherent nonlinear nature of the physical processes involved. We rederive the linear MTF and generalize it to include local acceleration and finite depth effects. The phase of the linear MTF is shown to be independent of the direction of long modulating waves. This is an artefact of the linearization of the nonlinear equations. A higher-order theory is also derived based on the truncated Hamiltonian for long modulating waves and dissipation by wave-wave interaction for modulated waves. This new theory includes higher-order derivatives of the source functional and, therefore, short-wave dissipation. Consequently, the phase of the modulation depends on the relative direction of long and short waves. It is shown that while the linear hydrodynamic MTF leads to higher-order statistics equivalent to the bispectrum, the new second-order MTF induces the trispectrum of surface elevation. A succinct derivation for the third-order MTF is given for completeness. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, Wallops Isl, VA 23337 USA. IFREMER, Brest, France. RP CNRS, IRPHE, Lab Interact Ocean Atmosphere, Parc Sci & Technol Luminy,Case 903,163 Ave Luminy, F-13288 Marseille 9, France. RI Chapron, Bertrand/O-6527-2015 NR 31 TC 12 Z9 12 U1 0 U2 1 PU ROYAL SOC PI LONDON PA 6-9 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 1364-5021 EI 1471-2946 J9 P ROY SOC A-MATH PHY JI Proc. R. Soc. A-Math. Phys. Eng. Sci. PD NOV 8 PY 2001 VL 457 IS 2015 BP 2585 EP 2608 PG 24 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 491GU UT WOS:000172101300003 ER PT J AU Okojie, RS Xhang, M Pirouz, P Tumakha, S Jessen, G Brillson, LJ AF Okojie, RS Xhang, M Pirouz, P Tumakha, S Jessen, G Brillson, LJ TI Observation of 4H-SiC to 3C-SiC polytypic transformation during oxidation SO APPLIED PHYSICS LETTERS LA English DT Article ID INTERFACE AB We have observed the formation of single and multiple stacking faults that sometimes give rise to 3C-SiC bands in a highly doped n-type 4H-SiC epilayer following dry thermal oxidation. Transmission electron microscopy following oxidation revealed single stacking faults and bands of 3C-SiC in a 4H-SiC matrix within the 4H-SiC epilayer. These bands, parallel to the (0001) basal plane, were not detected in unoxidized control samples. In addition to the 3.22 eV peak of 4H-SiC, Cathodoluminescence spectroscopy at 300 K after oxidation revealed a spectral peak at 2.5 eV photon energy that was not present in the sample prior to oxidation. The polytypic transformation is tentatively attributed to the motion of Shockley partial dislocations on parallel (0001) slip planes. The generation and motion of these partials may have been induced by stresses caused either by the heavy doping of the epilayer or nucleation from defect. (C) 2001 American Institute of Physics. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Mat Sci & Engn, Cleveland, OH 44106 USA. Ohio State Univ, Dept Elect Engn, Columbus, OH 43210 USA. RP Okojie, RS (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,Mail Stop 77-1, Cleveland, OH 44135 USA. NR 12 TC 112 Z9 112 U1 1 U2 15 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD NOV 5 PY 2001 VL 79 IS 19 BP 3056 EP 3058 DI 10.1063/1.1415347 PG 3 WC Physics, Applied SC Physics GA 487UY UT WOS:000171896600014 ER PT J AU Song, Q Putcha, L AF Song, Q Putcha, L TI Quantitation of promethazine and metabolites in urine samples using on-line solid-phase extraction and column-switching SO JOURNAL OF CHROMATOGRAPHY B LA English DT Article DE column switching; promethazine; promethazine sulfoxide; monodesmethylpromethazine sulfoxide; monodesmethyl promethazine ID PERFORMANCE LIQUID-CHROMATOGRAPHY; ONLINE TRACE-ENRICHMENT; HUMAN-PLASMA; ELECTROCHEMICAL DETECTION; MASS-SPECTROMETRY; FLUORESCENCE DETECTION; RETINOIC ACID; HUMAN SERUM; INJECTION; SORBENTS AB A chromatographic method for the quantitation of promethazine (PMZ) and its three metabolites in urine employing on-line solid-phase extraction and column-switching has been developed. The column-switching system described here uses an extraction column for the purification of PMZ and its metabolites from a urine matrix, The extraneous matrix interference was removed by flushing the extraction column with a gradient elution. The analytes of interest were then eluted onto an analytical column for further chromatographic separation using a mobile phase of greater solvent strength. This method is specific and sensitive with a range of 3.75-1400 ng/ml for PMZ and 2.5-1400 ng/ml for the metabolites promethazine sulfoxide, monodesmethyl promethazine sulfoxide and monodesmethyl promethazine. The lower limits of quantitation (LLOQ) were 3.75 ng/ml with less than 6.2% CV for PMZ and 2.50 ng/ml with less than 11.5% CV for metabolites based on a signal-to-noise ratio of 10:1 or greater. The accuracy and precision were within +/- 11.8% in bias and not greater than 5.5% CV in intra- and inter-assay precision for PMZ and metabolites. Method robustness was investigated using a Plackett-Bunnan experimental design. The applicability of the analytical method for pharmacokinetic studies in humans is illustrated. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Wyle Labs, Life Sci Syst & Serv, Houston, TX 77058 USA. RP Putcha, L (reprint author), NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Mail Code SD3, Houston, TX 77058 USA. NR 36 TC 10 Z9 13 U1 2 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-4347 J9 J CHROMATOGR B JI J. Chromatogr. B PD NOV 5 PY 2001 VL 763 IS 1-2 BP 9 EP 20 DI 10.1016/S0378-4347(01)00351-6 PG 12 WC Biochemical Research Methods; Chemistry, Analytical SC Biochemistry & Molecular Biology; Chemistry GA 486TB UT WOS:000171832100002 PM 11710587 ER PT J AU Bellamy, HD Snell, EH Lovelace, J Pokross, M Borgstahl, GEO AF Bellamy, HD Snell, EH Lovelace, J Pokross, M Borgstahl, GEO TI The high-mosaicity illusion: revealing the true physical characteristics of macromolecular crystals (vol D56, pg 986, 2000) SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Correction C1 Univ Toledo, Dept Chem, Toledo, OH 43606 USA. NASA, George C Marshall Space Flight Ctr, Struct Biol Lab, Huntsville, AL 35812 USA. Stanford Synchrotron Radiat Lab, Stanford, CA 94309 USA. RP Borgstahl, GEO (reprint author), Univ Toledo, Dept Chem, 2801 W Bancroft St, Toledo, OH 43606 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0907-4449 J9 ACTA CRYSTALLOGR D JI Acta Crystallogr. Sect. D-Biol. Crystallogr. PD NOV PY 2001 VL 57 BP 1754 EP 1754 DI 10.1107/S0907444901017115 PN 11 PG 1 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA 485TA UT WOS:000171778400056 ER PT J AU Dijk, DJ Neri, DF Wyatt, JK Ronda, JM Riel, E Cecco, ARD Hughes, RJ Elliott, AR Prisk, GK West, JB Czeisler, CA AF Dijk, DJ Neri, DF Wyatt, JK Ronda, JM Riel, E Cecco, ARD Hughes, RJ Elliott, AR Prisk, GK West, JB Czeisler, CA TI Sleep, performance, circadian rhythms, and light-dark cycles during two space shuttle flights SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE microgravity; entrainment; sleep homeostasis; rapid eye movement sleep; adaptation; melatonin; slow-wave sleep; cortisol; memory ID MELATONIN; SPACEFLIGHT; HUMANS; PROPENSITY; ASTRONAUTS; PACEMAKER; TEMPERATURE; MISSIONS; SYSTEM; PHASE AB Sleep, circadian rhythm, and neurobehavioral performance measures were obtained in five astronauts before, during, and after 16-day or 10-day space missions. In space, scheduled rest-activity cycles were 20-35 min shorter than 24 h. Light-dark cycles were highly variable on the flight deck, and daytime illuminances in other compartments of the spacecraft were very low (5.0-79.4 lx). In space, the amplitude of the body temperature rhythm was reduced and the circadian rhythm of urinary cortisol appeared misaligned relative to the imposed non-24-h sleep-wake schedule. Neurobehavioral performance decrements were observed. Sleep duration, assessed by questionnaires and actigraphy, was only similar to6.5 h/day. Subjective sleep quality diminished. Polysomnography revealed more wakefulness and less slow-wave sleep during the final third of sleep episodes. Administration of melatonin (0.3 mg) on alternate nights did not improve sleep. After return to earth, rapid eye movement (REM) sleep was markedly increased. Crewmembers on these flights experienced circadian rhythm disturbances, sleep loss, decrements in neurobehavioral performance, and postflight changes in REM sleep. C1 Harvard Univ, Sch Med, Brigham & Womens Hosp, Dept Med,Div Sleep Med, Boston, MA 02115 USA. NASA, Ames Res Ctr, Fatigue Countermeasures Program, Moffett Field, CA 94035 USA. Univ Calif San Diego, Dept Med, La Jolla, CA 92093 USA. RP Dijk, DJ (reprint author), Univ Surrey, Sch Biomed & Life Sci, Ctr Chronobiol, Guildford GU2 7XH, Surrey, England. RI Dijk, Derk-Jan/D-8387-2011; Wyatt, James/F-1785-2011 NR 44 TC 79 Z9 88 U1 5 U2 18 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0363-6119 J9 AM J PHYSIOL-REG I JI Am. J. Physiol.-Regul. Integr. Comp. Physiol. PD NOV PY 2001 VL 281 IS 5 BP R1647 EP R1664 PG 18 WC Physiology SC Physiology GA 483HW UT WOS:000171630200039 PM 11641138 ER PT J AU Yang, HX Konzett, J Prewitt, CT AF Yang, HX Konzett, J Prewitt, CT TI Crystal structure of phase X, a high pressure alkali-rich hydrous silicate and its anhydrous equivalent SO AMERICAN MINERALOGIST LA English DT Article ID NATURAL BULK COMPOSITIONS; UPPER-MANTLE; GPA; STABILITY; CLINOPYROXENE; AENIGMATITE; DIFFRACTION; POTASSIUM; NEUTRON; ZONE AB Phase X, ascribed by Luth (1995) to a hydrous K-rich silicate formed from the breakdown of K-amphibole at high pressures, was synthesized at 1250-1300 degreesC and 10-16 GPa in four different compositions: Na-1.78(Mg1.89Al0.13)Si2.02O7 (anhydrous sodic phase X), Na1.16K0.01(Mg1.89Al0.14) Si2.02O7H0.65 (sodic phase X), K1.85Mg2.06Si2.01O7 (anhydrous phase X), and K1.54Mg1.93Si1.89O7H1.04 (phase X). A general chemical formula for these phases can be expressed as A(2-x)M(2)Si(2)O(7)H(x), with A = K and/or Na, M = Mg and/or Al, and x = 0-1. Structure determination from single-crystal X-ray diffraction data shows that anhydrous sodic phase X is trigonal with space group P (3) over bar 1m. whereas the other three have an identical structure with space group P6(3)cm. Both P (3) over bar 1m and P6(3)cm structures are characterized by MgO6 octahedral layers that are stacked along the c axis and inter-linked together by Si2O7 tetrahedral dimers and K or Na cations. Within the MgO6 layers, each MgO6 octahedron shares three edges with neighboring MgO6 octahedra to form brucite-like layers with one out of three octahedral sites vacant. Large K or Na cations are situated right below and above each occupied octahedron in the MgO6 layers, whereas the Si2O7 groups are located below and above each vacant octahedron in the layers. The two types of structures, however, differ in the relative orientation of MgO6 octahedral layers, the coordination of K or Na, and the configuration Of SiO4 tetrahedral dimers. By comparison, the Na2Mg2Si2O7 phase synthesized by Gasparik and Litvin (1997) appears to have the stoichiometry identical to anhydrous sodic phase X. Hence, these two high-pressure phases are likely to possess the same structure, or at least are closely related to each other structurally. C1 Carnegie Inst Washington, Geophys Lab, Washington, DC 20015 USA. Carnegie Inst Washington, Ctr High Pressure Res, Washington, DC 20015 USA. RP Yang, HX (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 26 TC 13 Z9 13 U1 1 U2 3 PU MINERALOGICAL SOC AMER PI WASHINGTON PA 1015 EIGHTEENTH ST, NW SUITE 601, WASHINGTON, DC 20036 USA SN 0003-004X J9 AM MINERAL JI Am. Miner. PD NOV-DEC PY 2001 VL 86 IS 11-12 BP 1483 EP 1488 PG 6 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 496VF UT WOS:000172417200016 ER PT J AU Jahshan, SN Singleterry, RC AF Jahshan, SN Singleterry, RC TI The effect of stochastic perturbation of fuel distribution on the criticality of a one speed reactor and the development of multi-material multinomial line statistics SO ANNALS OF NUCLEAR ENERGY LA English DT Article ID MULTIPLYING SYSTEM; RANDOM GEOMETRY AB The effect of random fuel redistribution on the eigenvalue of a one-speed reactor is investigated, An ensemble of such reactors that are identical to a homogeneous reference critical reactor except for the fissile isotope density distribution is constructed such that it meets a set of well-posed redistribution requirements. The average eigenvalue, < k(eff) >, is evaluated when the total fissile loading per ensemble element, or realization, is conserved. The perturbation is proven to increase the reactor criticality on average when it is uniformly distributed. The various causes of the change in reactivity, and their relative effects are identified and ranked. From this, a path towards identifying the causes, and relative effects of reactivity fluctuations for the energy dependent problem is pointed to. The perturbation method of using multinomial distributions for representing the perturbed reactor is developed. This method has some advantages that can be of use in other stochastic problems. Finally, some of the features of this perturbation problem are related to other techniques that have been used for addressing similar problems. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Jahshan, SN (reprint author), 1901 Ferdon St, Ann Arbor, MI 48104 USA. NR 10 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0306-4549 J9 ANN NUCL ENERGY JI Ann. Nucl. Energy PD NOV PY 2001 VL 28 IS 17 BP 1697 EP 1716 DI 10.1016/S0306-4549(01)00014-7 PG 20 WC Nuclear Science & Technology SC Nuclear Science & Technology GA 464CQ UT WOS:000170516000002 ER PT J AU Lanoil, BD Sassen, R La Duc, MT Sweet, ST Nealson, KH AF Lanoil, BD Sassen, R La Duc, MT Sweet, ST Nealson, KH TI Bacteria and Archaea physically associated with Gulf of Mexico gas hydrates SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID RIBOSOMAL-RNA SEQUENCES; DEEP-SEA SEDIMENTS; OF-MEXICO; CONTINENTAL-SLOPE; METHANE OXIDATION; CHEMOSYNTHETIC COMMUNITIES; HYDROCARBON SEEPS; MARINE-SEDIMENTS; DIVERSITY; BACTERIOPLANKTON AB Although there is significant interest in the potential interactions of microbes with gas hydrate, no direct physical association between them has been demonstrated. We examined several intact samples of naturally occurring gas hydrate from the Gulf of Mexico for evidence of microbes. All samples were collected from anaerobic hemipelagic mud within the gas hydrate stability zone, at water depths in the ca. 540- to 2,000-m range. The delta C-13 of hydrate-bound methane varied from -45.1 parts per thousand Peedee belemnite (PDB) to -74.7 parts per thousand PDB, reflecting different gas origins. Stable isotope composition data indicated microbial consumption of methane or propane in some of the samples. Evidence of the presence of microbes was initially determined by 4,6-diamidino 2-phenylindole dihydrochloride (DAPI) total direct counts of hydrate-associated sediments (mean = 1.5 X 10(9) cells g(-1)) and gas hydrate (mean = 1.0 X 10(6) cells ml(-1)). Small-subunit rRNA phylogenetic characterization was performed to assess the composition of the microbial community in one gas hydrate sample (AT425) that had no detectable associated sediment and showed evidence of microbial methane consumption. Bacteria were moderately diverse within AT425 and were dominated by gene sequences related to several groups of Proteobacteria, as well as Actinobacteria and low-G + C Firmicutes. In contrast, there was low diversity of Archaea, nearly all of which were related to methanogenic Archaea, with the majority specifically related to Methanosaeta spp. The results of this study suggest that there is a direct association between microbes and gas hydrate, a finding that may have significance for hydrocarbon flux into the Gulf of Mexico and for life in extreme environments. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Texas A&M Univ, Geochem & Environm Res Grp, College Stn, TX 77845 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lanoil, BD (reprint author), Univ Calif Riverside, Dept Environm Sci, Riverside, CA 92521 USA. OI Lanoil, Brian/0000-0001-8603-8330 NR 55 TC 141 Z9 161 U1 1 U2 15 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1752 N ST NW, WASHINGTON, DC 20036-2904 USA SN 0099-2240 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD NOV PY 2001 VL 67 IS 11 BP 5143 EP 5153 DI 10.1128/AEM.67.11.5143-5153.2001 PG 11 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 488BL UT WOS:000171914100027 PM 11679338 ER PT J AU Jahnke, LL Eder, W Huber, R Hope, JM Hinrichs, KU Hayes, JM Des Marais, DJ Cady, SL Summons, RE AF Jahnke, LL Eder, W Huber, R Hope, JM Hinrichs, KU Hayes, JM Des Marais, DJ Cady, SL Summons, RE TI Signature lipids and stable carbon isotope analyses of octopus spring hyperthermophilic communities compared with those of Aquificales representatives SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID YELLOWSTONE-NATIONAL-PARK; HYDROGEN-OXIDIZING BACTERIUM; TRICARBOXYLIC-ACID CYCLE; NOV SP-NOV; GEN-NOV; THERMOPHILIC BACTERIUM; AQUIFEX-PYROPHILUS; MICROBIAL MATS; CO2 FIXATION; FATTY-ACIDS AB The molecular and isotopic compositions of lipid biomarkers of cultured Aquificales genera have been used to study the community and trophic structure of the hyperthermophilic pink streamers and vent biofilm from Octopus Spring. Thermocrinis ruber, Thermocrinis sp. strain HI 11/12, Hydrogenobacter thermophilas TK-6, Aquifex pyrophilus, and Aquifex aeolicus all contained glycerol-ether phospholipids as well as acyl glycerides. The n-C-20:1 and cy-C-21 fatty acids dominated all of the Aquificales, while the alkyl glycerol ethers were mainly C-18:0, These Aquificales biomarkers were major constituents of the lipid extracts of two Octopus Spring samples, a biofilm associated with the siliceous vent walls, and the well-known pink streamer community (PSC). Both the biofilm and the PSC contained mono- and dialkyl glycerol ethers in which C-18 and C-20 alkyl groups were prevalent. Phospholipid fatty acids included both the Aquificales n-C-20:1 and cy-C-21, plus a series of isobranched fatty acids (i-C-15:0 to i-C-21:0), indicating an additional bacterial component. Biomass and lipids from the PSC were depleted in C-13 relative to source water CO2 by 10.9 and 17.2 parts per thousand, respectively. The C20-21 fatty acids of the PSC were less depleted than the iso-branched fatty acids, 18.4 and 22.6 parts per thousand, respectively. The biomass of T. ruber grown on CO2 was depleted in C-13 by only 3.3 parts per thousand relative to C source. In contrast, biomass was depleted by 19.7 parts per thousand when formate was the C source. Independent of carbon source, T. ruber lipids were heavier than biomass (+1.3 parts per thousand). The depletion in the C20-21 fatty acids from the PSC indicates that Thermocrinis biomass must be similarly depleted and too light to be explained by growth on CO2. Accordingly, Thermocrinis in the PSC is likely to have utilized formate, presumably generated in the spring source region. C1 NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. Univ Regensburg, Lehrstuhl Mikrobiol, D-93053 Regensburg, Germany. Univ Regensburg, Archaeenzentrum, D-93053 Regensburg, Germany. Australian Geol Survey Org, Canberra, ACT 2601, Australia. Woods Hole Oceanog Inst, Dept Geol & Geophys, Woods Hole, MA 02543 USA. Portland State Univ, Dept Geol, Portland, OR 97201 USA. RP Jahnke, LL (reprint author), NASA, Ames Res Ctr, Exobiol Branch, M-S 239-4, Moffett Field, CA 94035 USA. RI Hinrichs, Kai-Uwe/C-7675-2009 OI Hinrichs, Kai-Uwe/0000-0002-0739-9291 NR 59 TC 121 Z9 124 U1 0 U2 25 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1752 N ST NW, WASHINGTON, DC 20036-2904 USA SN 0099-2240 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD NOV PY 2001 VL 67 IS 11 BP 5179 EP 5189 DI 10.1128/AEM.67.11.5179-5189.2001 PG 11 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 488BL UT WOS:000171914100032 PM 11679343 ER PT J AU Veselovskii, LA Cha, HK Kim, DH Choi, SC Lee, JM AF Veselovskii, LA Cha, HK Kim, DH Choi, SC Lee, JM TI Study of atmospheric water in gaseous and liquid state by using combined elastic-Raman depolarization lidar SO APPLIED PHYSICS B-LASERS AND OPTICS LA English DT Article ID VAPOR; SCATTERING; RATIO; BACKSCATTER; EXTINCTION AB A combined elastic-Raman lidar system based on a tripled Nd:YAG laser is used for the separate detection of elastic backscatter and Raman signals from atmospheric nitrogen, water vapor and liquid water and for their depolarization measurement. Vertical profiles of water-vapor and liquid-water content measured under clear-sky conditions behave differently: inside the boundary layer the ratio of liquid-water to water-vapor Raman backscatters rises with attitude. The depolarization measurements bring additional information about atmospheric scattering. The observed depolarization ratio of the water-vapor Raman signal is about 14%. while for liquid water this ratio varies in the 30%-75% range, which exceeds the depolarization of bulk water and is attributed to the water-aerosol effects. Raman contours of water vapor and liquid water are partially overlapped. and bleed-through of liquid-water Raman backscatter leads to enhancement of depolarization of the water-vapor Raman signal. This parameter may be used as a convenient indicator of liquid-water interference in water vapor measurements. C1 Moscow Gen Phys Inst, Phys Instrumentat Ctr, Moscow 142190, Russia. Korea Atom Energy Res Inst, Taejon 305600, South Korea. RP Veselovskii, LA (reprint author), NASA, Goddard Space Flight Ctr, Code 924, Greenbelt, MD 20771 USA. EM iveselov@pop900.gsfc.nasa.gov NR 19 TC 6 Z9 6 U1 0 U2 3 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0946-2171 EI 1432-0649 J9 APPL PHYS B-LASERS O JI Appl. Phys. B-Lasers Opt. PD NOV PY 2001 VL 73 IS 7 BP 739 EP 744 DI 10.1007/s003400100732 PG 6 WC Optics; Physics, Applied SC Optics; Physics GA 503KY UT WOS:000172798700015 ER PT J AU Gebhardt, K Lauer, TR Kormendy, J Pinkney, J Bower, GA Green, R Gull, T Hutchings, JB Kaiser, ME Nelson, CH Richstone, D Weistrop, D AF Gebhardt, K Lauer, TR Kormendy, J Pinkney, J Bower, GA Green, R Gull, T Hutchings, JB Kaiser, ME Nelson, CH Richstone, D Weistrop, D TI M33: A galaxy with no supermassive black hole SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : general; galaxies : nuclei ID 3-INTEGRAL MODELS; DARK-MATTER; KINEMATICS; TRIPLET; NUCLEUS; SPECTRA; HALO AB Galaxies that contain bulges appear to contain central black holes whose masses correlate with the velocity dispersion of the bulge. We show that no corresponding relationship applies in the pure disk galaxy M33. Three-integral dynamical models fit Hubble Space Telescope WFPC2 photometry and Space Telescope Imaging Spectrograph spectroscopy best if the central black hole mass is zero. The upper limit is 1500 M.. This is significantly below the mass expected from the velocity dispersion of the nucleus and far below any mass predicted from the disk kinematics. Our results suggest that supermassive black holes are associated only with galaxy bulges and not with their disks. C1 Univ Texas, Dept Astron, Austin, TX 78712 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Victoria, BC V9E 2E7, Canada. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Nevada, Dept Phys, Las Vegas, NV 89154 USA. RP Gebhardt, K (reprint author), Univ Texas, Dept Astron, Mail Code C1400, Austin, TX 78712 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 35 TC 169 Z9 169 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD NOV PY 2001 VL 122 IS 5 BP 2469 EP 2476 DI 10.1086/323481 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 491AP UT WOS:000172086100019 ER PT J AU Bellazzini, M Pecci, FF Ferraro, FR Galleti, S Catelan, M Landsman, WB AF Bellazzini, M Pecci, FF Ferraro, FR Galleti, S Catelan, M Landsman, WB TI Age as the second parameter in NGC 288/NGC 362? I. Turnoff ages: A purely differential comparison SO ASTRONOMICAL JOURNAL LA English DT Review DE color-magnitude diagrams; globular clusters : general; globular clusters : individual (NGC 288, NGC 362, NGC 1851); stars : horizontal-branch; stars : Population II ID GLOBULAR-CLUSTER NGC-288; HORIZONTAL-BRANCH STARS; RR-LYRAE VARIABLES; COLOR-MAGNITUDE DIAGRAMS; CCD PHOTOMETRY; GALACTIC HALO; 2ND-PARAMETER PHENOMENON; STELLAR POPULATIONS; HELIUM ABUNDANCE; BLUE STRAGGLERS AB We present deep V, I photometry of the globular clusters NGC 288, 362, and 1851 obtained during a single observational run under strictly homogeneous conditions. We use the bimodal horizontal branch (HB) of NGC 1851 as a "bridge" to obtain the optimum relative match between the HBs of NGC 288 and NGC 362. In this way we can effectively remove the uncertainties associated with distance, reddening, and inhomogeneities in the absolute calibration, thus obtaining a very robust, purely differential estimate of the age difference between these two clusters. According to the bridge test, NGC 288 is found to be older than NGC 362 by 2 +/- 1 Gyr. This result is fully confirmed also by all classical differential age diagnostics, either based on the luminosity (DeltaV(TO)(HB)) or color [delta (V-I)(@2.5)] of the main-sequence turnoff point. C1 Osservatorio Astron Bologna, I-40127 Bologna, Italy. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. NASA, Raytheon ITSS, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Osservatorio Astron Bologna, Via Ranzani 1, I-40127 Bologna, Italy. EM bellazzini@bo.astro.it; flavio@bo.astro.it; ferraro@bo.astro.it; l_galleti@bo.astro.it; catelan@virginia.edu; landsman@mpb.gsfc.nasa.gov RI Bellazzini , Michele/O-9373-2015 OI Bellazzini , Michele/0000-0001-8200-810X NR 102 TC 43 Z9 43 U1 1 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD NOV PY 2001 VL 122 IS 5 BP 2569 EP 2586 DI 10.1086/323711 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 491AP UT WOS:000172086100026 ER PT J AU Pritzl, BJ Smith, HA Catelan, M Sweigart, AV AF Pritzl, BJ Smith, HA Catelan, M Sweigart, AV TI Variable stars in the unusual, metal-rich, globular cluster NGC 6441 SO ASTRONOMICAL JOURNAL LA English DT Article DE globular clusters : individual (NGC 6441); RR Lyrae variable ID RR-LYRAE STARS; HORIZONTAL-BRANCH STARS; OOSTERHOFF PERIOD GROUPS; BVI-CCD PHOTOMETRY; OMEGA-CENTAURI; LIGHT CURVES; STANDARD STARS; HELIUM FLASH; CORE MASS; MILKY-WAY AB We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6441 using time-series BV photometry. The total number of variables found near NGC 6441 has been increased to similar to 104, with 48 new variables being found in this survey. A significant number of the variables are RR Lyrae stars (similar to 46), most of which are probable cluster members. As was noted by Layden et al. in 1999, the periods of the fundamental-mode RR Lyrae stars are unusually long compared with field stars of similar metallicity. The existence of these long-period RRab stars is consistent with Sweigart & Catelan's prediction that the horizontal branch of NGC 6441 is unusually bright. This result implies that the metallicity-luminosity relationship for RR Lyrae stars is not universal. We discuss the difficulty in determining the Oosterhoff classification of NGC 6441 because of the unusual nature of its RR Lyrae stars. A number of ab-type RR Lyrae stars are found to be both brighter and redder than the other probable RRab found along the horizontal branch, which may be a result of blending with stars of redder color. A smaller than usual gap is found between the shortest period fundamental-mode and the longest period first-overtone-mode RR Lyrae stars. We determine the reddening of the cluster to be E(B-V) = 0.51 +/- 0.02 mag, with substantial differential reddening across the face of the cluster. The mean V magnitude of the RR Lyrae is found to be 17.51 +/- 0.02 mag, resulting in a distance of 10.4-11.9 kpc, for a range of assumed values of [M-V] for RR Lyrae stars. The possibility that stars in NGC 6441 may span a range in [Fe/H] is also discussed. C1 Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Natl Opt Astron Observ, POB 26732, Tucson, AZ 85726 USA. EM pritzl@pa.msu.edu; smith@pa.msu.edu; catelan@virginia.edu; sweigart@bach.gsfc.nasa.gov NR 87 TC 56 Z9 56 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD NOV PY 2001 VL 122 IS 5 BP 2600 EP 2626 DI 10.1086/323447 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 491AP UT WOS:000172086100028 ER PT J AU Ivezic, Z Tabachnik, S Rafikov, R Lupton, RH Quinn, T Hammergren, M Eyer, L Chu, J Armstrong, JC Fan, XH Finlator, K Geballe, TR Gunn, JE Hennessy, GS Knapp, GR Leggett, SK Munn, JA Pier, JR Rockosi, CM Schneider, DP Strauss, MA Yanny, B Brinkmann, J Csabai, I Hindsley, RB Kent, S Lamb, DQ Margon, B McKay, TA Smith, JA Waddel, P York, DG AF Ivezic, Z Tabachnik, S Rafikov, R Lupton, RH Quinn, T Hammergren, M Eyer, L Chu, J Armstrong, JC Fan, XH Finlator, K Geballe, TR Gunn, JE Hennessy, GS Knapp, GR Leggett, SK Munn, JA Pier, JR Rockosi, CM Schneider, DP Strauss, MA Yanny, B Brinkmann, J Csabai, I Hindsley, RB Kent, S Lamb, DQ Margon, B McKay, TA Smith, JA Waddel, P York, DG CA SDSS Collaboration TI Solar system objects observed in the Sloan Digital Sky Survey commissioning data SO ASTRONOMICAL JOURNAL LA English DT Article DE Kuiper belt; minor planets, asteroids; solar system : general ID KUIPER-BELT OBJECTS; EARTH-APPROACHING ASTEROIDS; FALL EQUATORIAL STRIPE; SIZE DISTRIBUTION; MAGNITUDE DISTRIBUTIONS; QUASARS; STARS; SPECTROPHOTOMETRY; CLASSIFICATION; POPULATIONS AB We discuss measurements of the properties of similar to 13,000 asteroids detected in 500 deg(2) of sky in the Sloan Digital Sky Survey (SDSS) commissioning data. The moving objects are detected in the magnitude range 14 18). The observed counts imply that there are about 670,000 objects with D>1 km in the asteroid belt, or up to 3 times less than previous estimates. The revised best estimate for the impact rate of the so-called "killer" asteroids (D>1 km) is about 1 every 500,000 yr, uncertain to within a factor of 2. We predict that by its completion SDSS will obtain about 100,000 near simultaneous five-band measurements for a subset drawn from 340,000 asteroids brighter than r* <21.5 at opposition. Only about a third of these asteroids have been previously observed, and usually in just one band. The distribution of main-belt asteroids in the four-dimensional SDSS color space is bimodal, and the two groups can be associated with S- (rocky) and C-(carbonaceous) type asteroids. A strong bimodality is also seen in the heliocentric distribution of asteroids : the inner belt is dominated by S-type asteroids centered at R2.8 AU, while C-type asteroids, centered at R similar to 3.2 AU, dominate the outer belt. The median color of each class becomes bluer by about 0.03 mag AU(-1) as the heliocentric distance increases. The observed number ratio of S and C asteroids in a sample with r* <21.5 is 1.5 : 1, while in a sample limited by absolute magnitude it changes from 4: 1 at 2 AU, to 1: 3 at 3.5 AU. In a size-limited sample with D>1 km, the number ratio of S and C asteroids in the entire main belt is 1: 2.3. The colors of Hungarias, Mars crossers, and near-Earth objects, selected by their velocity vectors, are more similar to the C-type than to S-type asteroids. In about 100 deg(2) of sky along the celestial equator observed twice 2 days apart, we find one plausible Kuiper belt object (KBO) candidate, in agreement with the expected KBO surface density. The colors of the KBO candidate are significantly redder than the asteroid colors, in agreement with colors of known KBOs. We explore the possibility that SDSS data can be used to search for very red, previously uncataloged asteroids observed by 2MASS, by extracting objects without SDSS counterparts. We do not find evidence for a significant population of such objects; their contribution is no more than 10% of the asteroid population. C1 Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Washington, Dept Astron, Seattle, WA 98195 USA. Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. Ramapo High Sch, Spring Valley, NY 10977 USA. Joint Astron Ctr, United Kingdom Infrared Telescope, Hilo, HI 96720 USA. USN Observ, Washington, DC 20392 USA. USN Observ, Flagstaff Stn, Flagstaff, AZ 86002 USA. Univ Chicago, Ctr Astron & Astrophys, Chicago, IL 60637 USA. Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA. Fermilab Natl Accelerator Lab, Batavia, IL 60510 USA. Apache Point Observ, Sunspot, NM 88349 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Eotvos Lorand Univ, Dept Phys Complex Syst, H-1117 Budapest, Hungary. USN, Remote Sensing Div, Res Lab, Washington, DC 20375 USA. Univ Michigan, Dept Phys, Ann Arbor, MI 48109 USA. Univ Wyoming, Dept Phys & Astron, Laramie, WY 82071 USA. NASA, USRA, SOFIA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ivezic, Z (reprint author), Princeton Univ Observ, Peyton Hall, Princeton, NJ 08544 USA. RI Margon, Bruce/B-5913-2012; Csabai, Istvan/F-2455-2012; McKay, Timothy/C-1501-2009; Finlator, Kristian/M-4809-2014; OI McKay, Timothy/0000-0001-9036-6150; Finlator, Kristian/0000-0002-0496-1656; Armstrong, John/0000-0003-2009-1459; Csabai, Istvan/0000-0001-9232-9898; Leggett, Sandy/0000-0002-3681-2989 NR 77 TC 239 Z9 241 U1 0 U2 7 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD NOV PY 2001 VL 122 IS 5 BP 2749 EP 2784 DI 10.1086/323452 PG 36 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 491AP UT WOS:000172086100043 ER PT J AU Vuong, MH Cambresy, L Epchtein, N AF Vuong, MH Cambresy, L Epchtein, N TI Low mass T Tauri and young brown dwarf candidates in the Chamaeleon II dark cloud found by DENIS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ISM : clouds; ISM : dust, extinction; ISM : individual objects : Chamaeleon ID CHAMELEON-II; MAIN-SEQUENCE; STARS; STELLAR; EXTINCTION; LUMINOSITY AB We define a sample designed to select low-mass T Tauri stars and young brown dwarfs using DENIS data in the Chamaeleon II molecular cloud. We use a star count method to construct an extinction map of the Chamaeleon II cloud. We select our low-mass T Tauri star and young brown dwarf candidates by their strong infrared color excess in the I - J/J - K-s color-color dereddened diagram. We retain only objects with colors I - J greater than or equal to 2, and spatially distributed in groups around the cloud cores. This provides a sample of 70 stars of which 4 are previously known T Tauri stars. We have carefully checked the reliability of all these objects by visual inspection of the DENIS images. Thanks to the association of the optical I band to the infra-red J and K-s bands in DENIS, we can apply this selection method to all star formation regions observed in the southern hemisphere. We also identify six DENIS sources with X-ray sources detected by ROSAT. Assuming that they are reliable low-mass candidates and using the evolutionary models for low-mass stars, we estimate the age of these sources between 1 Myr and <10 Myr. C1 Observ Cote Azur, Dept Fresnel, F-06304 Nice, France. CALTECH, Jet Prop Lab, IPAC, Pasadena, CA 91109 USA. RP Vuong, MH (reprint author), CEA Saclay, Serv Astrophys, F-91191 Gif Sur Yvette, France. EM vuong@cea.fr NR 30 TC 19 Z9 19 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 2001 VL 379 IS 1 BP 208 EP 214 DI 10.1051/0004-6361:20011259 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490CA UT WOS:000172031800027 ER PT J AU Oudmaijer, RD Palacios, J Eiroa, C Davies, JK de Winter, D Ferlet, R Garzon, F Grady, CA Cameron, A Deeg, HJ Harris, AW Horne, K Merin, B Miranda, LF Montesinos, B Mora, A Penny, A Quirrenbach, A Rauer, H Schneider, J Solano, E Tsapras, Y Wesselius, PR AF Oudmaijer, RD Palacios, J Eiroa, C Davies, JK de Winter, D Ferlet, R Garzon, F Grady, CA Cameron, A Deeg, HJ Harris, AW Horne, K Merin, B Miranda, LF Montesinos, B Mora, A Penny, A Quirrenbach, A Rauer, H Schneider, J Solano, E Tsapras, Y Wesselius, PR TI EXPORT: Optical photometry and polarimetry of Vega-type and pre-main sequence stars SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE techniques : photometry; techniques : polarimetry; stars : circumstellar matter; stars : pre-main sequence; stars : variables : general ID HERBIG AE/BE STARS; BETA-PICTORIS PHENOMENON; YOUNG STARS; PHOTOPOLARIMETRIC ACTIVITY; WAVELENGTH DEPENDENCE; UX ORIONIS; TAURI; GIANTS; DUST; SPECTROSCOPY AB This paper presents optical UBVRI broadband photo-polarimetry of the EXPORT sample obtained at the 2.5 m Nordic Optical Telescope. The database consists of multi-epoch photo-polarimetry of 68 pre-main-sequence and main-sequence stars. An investigation of the polarization variability indicates that 22 objects are variable at the 3 sigma level in our data. All these objects are pre-main sequence stars, consisting of both T Tauri and Herbig Ae/Be objects while the main sequence, Vega type and post-T Tauri type objects are not variable. The polarization properties of the variable sources are mostly indicative of the UXOR-type behaviour; the objects show highest polarization when the brightness is at minimum. We add seven new objects to the class of UXOR variables (BH Cep, VX Cas, DK Tau, HK Ori, LkH alpha 234, KK Oph and RY Ori). The main reason for their discovery is the fact that our data-set is the largest in its kind, indicating that many more young UXOR-type pre-main sequence stars remain to be discovered. The set of Vega-like systems has been investigated for the presence of intrinsic polarization. As they lack variability, this was done using indirect methods, and apart from the known case of BD+31 degrees 643, the following stars were found to be strong candidates to exhibit polarization due to the presence of circumstellar disks: 51 Oph, BD+31 degrees 643C, HD 58647 and HD 233517. C1 Dept Phys & Astron, Leeds LS2 9JT, W Yorkshire, England. Inst Astrofis Canarias, Tenerife 38200, Spain. Inst Astrofis Andalucia, E-18080 Granada, Spain. TNO, TPD Space Instrumentat, NL-2600 AD Delft, Netherlands. CNRS, Inst Astrophys Paris, F-75014 Paris, France. NASA, Goddard Space Flight Ctr, NOAO, STIS, Greenbelt, MD 20771 USA. Univ St Andrews, St Andrews KY16 9SS, Fife, Scotland. Joint Astron Ctr, Hilo, HI 96720 USA. DLR, Inst Space Sensor Technol & Planetary Explorat, D-12489 Berlin, Germany. LAEFF, VILSPA, Madrid 28080, Spain. Univ Autonoma Madrid, Fac Ciencias, Dipartimento Fis Teor, E-28049 Madrid, Spain. Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England. Univ Calif San Diego, Dept Phys, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Observ Paris, F-92195 Meudon, France. Univ Groningen, SRON, NL-9700 AV Groningen, Netherlands. RP Dept Phys & Astron, E C Stoner Bldg, Leeds LS2 9JT, W Yorkshire, England. EM roud@ast.leeds.ac.uk RI Solano, Enrique/C-2895-2017; Montesinos, Benjamin/C-3493-2017; OI Montesinos, Benjamin/0000-0002-7982-2095; Cameron, Andrew/0000-0002-8863-7828; Deeg, Hans-Jorg/0000-0003-0047-4241; Merin, Bruno/0000-0002-8555-3012 NR 36 TC 68 Z9 69 U1 0 U2 3 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 2001 VL 379 IS 2 BP 564 EP 578 DI 10.1051/0004-6361:20011331 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 493VE UT WOS:000172243500021 ER PT J AU Garcia-Sanchez, J Weissman, PR Preston, RA Jones, DL Lestrade, JF Latham, DW Stefanik, RP Paredes, JM AF Garcia-Sanchez, J Weissman, PR Preston, RA Jones, DL Lestrade, JF Latham, DW Stefanik, RP Paredes, JM TI Stellar encounters with the solar system SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE comets : general; stars : general; stars : kinematics; Galaxy : general ID OORT CLOUD; SPIRAL STRUCTURE; MASS DENSITY; LUMINOSITY FUNCTION; GALACTIC CONSTANTS; PROPER MOTIONS; COMET SHOWERS; UPPER EOCENE; STAR COUNTS; GALAXY AB We continue our search, based on Hipparcos data, for stars which have encountered or will encounter the solar system (Garcia-Sanchez et al. 1999). Hipparcos parallax and proper motion data are combined with ground-based radial velocity measurements to obtain the trajectories of stars relative to the solar system. We have integrated all trajectories using three different models of the galactic potential: a local potential model, a global potential model, and a perturbative potential model. The agreement between the models is generally very good. The time period over which our search for close passages is valid is about +/- 10 Myr. Based on the Hipparcos data, we find a frequency of stellar encounters within one parsec of the Sun of 2.3 +/-0.2 per Myr. However, we also find that the Hipparcos data is observationally incomplete. By comparing the Hipparcos observations with the stellar luminosity function for star systems within 50 pc of the Sun, we estimate that only about one-fifth of the stars or star systems were detected by Hipparcos. Correcting for this incompleteness, we obtain a value of 11.7 +/-1.3 stellar encounters per Myr within one pc of the Sun. We examine the ability of two future missions, FAME and GAIA, to extend the search for past and future stellar encounters with the Sun. C1 Univ Barcelona, Dept Astron & Meteorol, E-08028 Barcelona, Spain. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Observ Paris, DEMIRM, CNRS 8540, F-75014 Paris, France. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Garcia-Sanchez, J (reprint author), Univ Barcelona, Dept Astron & Meteorol, Av Diagonal 647, E-08028 Barcelona, Spain. EM joan.garcia@tin.it OI Paredes, Josep M./0000-0002-1566-9044 NR 83 TC 65 Z9 65 U1 0 U2 2 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 2001 VL 379 IS 2 BP 634 EP 659 DI 10.1051/0004-6361:20011330 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 493VE UT WOS:000172243500029 ER PT J AU Balucinska-Church, M Barnard, R Church, MJ Smale, AP AF Balucinska-Church, M Barnard, R Church, MJ Smale, AP TI Neutron star blackbody contraction during flaring in X1624-490 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE X rays : stars; stars : individual : X1624-490; stars : neutron; binaries : close; accretion : accretion disks ID X-RAY BINARIES; BEPPOSAX OBSERVATION; MODEL ATMOSPHERES; ACCRETION DISKS; SCORPIUS X-1; SPECTRA; EMISSION; INSTABILITY; VARIABILITY; ABSORPTION AB We present results of an extensive investigation of the physical changes taking place in the emission regions of the LMXB X1624-490 during strong flaring in observations made using RXTE in 1997 and 1999. Based on the detailed light curve, we propose that the flaring consists of a superposition of X-ray bursts. It is shown that major changes take place in the blackbody emission component, the temperature kT(BB) increasing to similar to 2.2 keV in flaring. Remarkably, the blackbody area decreases by a factor of similar to 5 in flaring. During are evolution, the blackbody luminosity remains approximately constant, constituting a previously unknown Eddington limiting effect which we propose is due to radiation pressure of the blackbody as kTBB increases affecting the inner disk or accretion ow resulting in a decreased emitting area on the star. We argue that the large decrease in area cannot be explained in terms of modification of the blackbody spectrum by electron scattering in the atmosphere of the neutron star. The height of the emitting region on the non-flaring neutron star is shown to agree with the height of the inner radiatively-supported accretion disk as found for sources in the ASCA survey of LMXB of Church & Balucinska-Church (2001). The decrease in height during flaring is discussed in terms of possible models, including radial accretion ow onto the stellar surface and the theory of accretion ow spreading on the neutron star surface of Inogamov & Sunyaev (1999). We demonstrate that the intensity of the broad iron line at 6.4 keV is strongly correlated with the luminosity of the blackbody emission from the neutron star, and discuss the probable origin of this line in the ADC. Finally, possible reasons for non-detection of a reflection component in this source, and LMXB in general, are discussed. C1 Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. Jagiellonian Univ, Inst Astron, PL-30244 Krakow, Poland. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. RP Balucinska-Church, M (reprint author), Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. EM mbc@star.sr.bham.ac.uk; alan@osiris.gsfc.nasa.gov NR 48 TC 16 Z9 16 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 2001 VL 378 IS 3 BP 847 EP 860 DI 10.1051/0004-6361:20011157 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487VA UT WOS:000171897200016 ER PT J AU Charnley, SB Rodgers, SD Ehrenfreund, P AF Charnley, SB Rodgers, SD Ehrenfreund, P TI Gas-grain chemical models of star-forming molecular clouds as constrained by ISO and SWAS observations SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE molecular abundances; astrochemistry; molecular processes ID DENSE INTERSTELLAR CLOUDS; TIME-DEPENDENT CHEMISTRY; WAVE-ASTRONOMY-SATELLITE; ATOMIC CARBON; DEUTERIUM FRACTIONATION; DARK CLOUD; INFRARED-SPECTROSCOPY; DESORPTION PROCESSES; UMIST DATABASE; TMC-1 RIDGE AB We have investigated the gaseous and solid state molecular composition of dense interstellar material that periodically experiences processing in the shock waves associated with ongoing star formation. Our motivation is to confront these models with the stringent abundance constraints on CO(2), H(2)O and O(2), in both gas and solid phases, that have been set by ISO and SWAS. We also compare our results with the chemical composition of dark molecular clouds as determined by ground-based telescopes. Beginning with the simplest possible model needed to study molecular cloud gas-grain chemistry, we only include additional processes where they are clearly required to satisfy one or more of the ISO-SWAS constraints. When CO, N(2) and atoms of N, C and S are efficiently desorbed from grains, a chemical quasi-steady-state develops after about one million years. We find that accretion of CO(2) and H(2)O cannot explain the [CO(2)/H(2)O](ice) ISO observations; as with previous models, accretion and reaction of oxygen atoms are necessary although a high O atom abundance can still be derived from the CO that remains in the gas. The observational constraints on solid and gaseous molecular oxygen are both met in this model. However, we find that we cannot explain the lowest H(2)O abundances seen by SWAS or the highest atomic carbon abundances found in molecular clouds; additional chemical processes are required and possible candidates are given. One prediction of models of this type is that there should be some regions of molecular clouds which contain high gas phase abundances of H(2)O, O(2) and NO. A further consequence, we find, is that interstellar grain mantles could be rich in NH(2)OH and NO(2). The search for these regions, as well as NH(2)OH and NO(2) in ices and in hot cores, is an important further test of this scenario. The model can give good agreement with observations of simple molecules in dark molecular clouds such as TMC-1 and L134N. Despite the fact that S atoms are assumed to be continously desorbed from grain surfaces, we find that the sulphur chemistry independently experiences an "accretion catastrophe". The S-bearing molecular abundances cease to lie within the observed range after about 3 x 10(6) years and this indicates that there may be at least two efficient surface desorption mechanisms operating in dark clouds - one quasi-continous and the other operating more sporadically on this time-scale. We suggest that mantle removal on short time-scales is mediated by clump dynamics, and by the effects of star formation on longer time-scales. The applicability of this type of dynamical-chemical model for molecular cloud evolution is discussed and comparison is made with other models of dark cloud chemistry. C1 NASA, Div Space Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. Leiden Observ, NL-2300 RA Leiden, Netherlands. RP Ehrenfreund, P (reprint author), NASA, Div Space Sci, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. EM pascale@strwchem.strw.leidenuniv.nf RI Charnley, Steven/C-9538-2012 NR 93 TC 74 Z9 74 U1 1 U2 4 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 2001 VL 378 IS 3 BP 1024 EP 1036 DI 10.1051/0004-6361:20011193 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487VA UT WOS:000171897200030 ER PT J AU Moran, T Gopalswamy, N Dammasch, IE Wilhelm, K AF Moran, T Gopalswamy, N Dammasch, IE Wilhelm, K TI A multi-wavelength study of solar coronal-hole regions showing radio enhancements SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE Sun : radio radiation; Sun : UV radiation; Sun : chromosphere; Sun : transition region; Sun : corona ID TRANSITION-REGION; MILLIMETER WAVELENGTHS; MICROWAVE STRUCTURE; SOHO MISSION; POLAR-CAP; QUIET SUN; GHZ; EMISSION; BRIGHTENINGS; CHROMOSPHERE AB We observed 17 GHz microwave-enhanced regions in equatorial coronal holes (ECH) together with extreme-ultraviolet (EUV), far-ultraviolet (FUV) and visible emissions in a search for temperature increases which might explain the bright spots in radio wavelengths. The ultraviolet (UV) observations span a wide range of formation temperatures (8000 K to 630 000 K). Increased UV emission was observed at the approximate location of the radio enhancements, but unlike the radio brightening, the UV emission did not exceed the mean quiet sun level. However, there were two observations showing increased H alpha brightness in radio enhancements above mean quiet sun levels. No H alpha bright spots were detected in ECHs outside of radio enhancement regions. The ECH H alpha bright spots were caused by bright fibrils, bright points and a lack of dark fibrils. Since the 17 GHz and H alpha enhancements are co-spatial, have equal integrated normalized enhanced emission and brightness temperatures, the observations suggest that the radio enhancements are caused by increased fibril radio emission. In addition, increased Fe XII EUV emission was recorded at the location of some well-defined radio enhancements, which were the bases of coronal plumes. Since the radio brightness temperature is much lower than the Fe XII formation temperature, the radio and EUV enhancements are likely both related to the presence of concentrated magnetic flux, but do not arise from the same physical layer. C1 Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Max Planck Inst Aeron, D-37191 Katlenburg Lindau, Germany. RP Moran, T (reprint author), Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. EM tmoran@cspsw4.nascom.nasa.gov RI Gopalswamy, Nat/D-3659-2012 NR 35 TC 11 Z9 11 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 2001 VL 378 IS 3 BP 1037 EP 1045 DI 10.1051/0004-6361:20010569 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487VA UT WOS:000171897200031 ER PT J AU Maeno, T Orito, S Matsunaga, H Abe, K Anraku, K Asaoka, Y Fujikawa, M Imori, M Makida, Y Matsui, N Matsumoto, H Mitchell, J Mitsui, T Moiseev, A Motoki, M Nishimura, J Nozaki, M Ormes, J Saeki, T Sanuki, T Sasaki, M Seo, ES Shikaze, Y Sonoda, T Streitmatter, R Suzuki, J Tanaka, K Ueda, I Wang, JZ Yajima, N Yamagami, T Yamamoto, A Yoshida, T Yoshimura, K AF Maeno, T Orito, S Matsunaga, H Abe, K Anraku, K Asaoka, Y Fujikawa, M Imori, M Makida, Y Matsui, N Matsumoto, H Mitchell, J Mitsui, T Moiseev, A Motoki, M Nishimura, J Nozaki, M Ormes, J Saeki, T Sanuki, T Sasaki, M Seo, ES Shikaze, Y Sonoda, T Streitmatter, R Suzuki, J Tanaka, K Ueda, I Wang, JZ Yajima, N Yamagami, T Yamamoto, A Yoshida, T Yoshimura, K TI Successive measurements of cosmic-ray antiproton spectrum in a positive phase of the solar cycle SO ASTROPARTICLE PHYSICS LA English DT Article DE cosmic-ray; antiproton; measurements; solar modulation ID MINIMUM; NUCLEI; FLUX; ANNIHILATION; ABSORPTION; MODULATION; RADIATION; RANGE; RATIO AB The energy spectrum of cosmic-ray antiprotons (p's) has been measured by BESS successively in 1993, 1995, 1997 and 1998. In total, 848 (p) over bar 's were clearly identified in energy range 0.18-4.20 GeV. From these successive measurements of the (p) over bar spectrum at various solar activity, we discuss about the effect of the solar modulation and the origin of cosmic-ray (p) over bar 's. The (p) over bar /p ratios showed no distinctive year-to-year variation during the positive Sun's polarity phase. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Kobe Univ, Kobe, Hyogo 6578501, Japan. Univ Tokyo, Tokyo 1130033, Japan. KEK, High Energy Accelerator Res Org, Tsukuba, Ibaraki 3050801, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, College Pk, MD 20742 USA. ISAS, Sagamihara, Kanagawa 2298510, Japan. RP Maeno, T (reprint author), Kobe Univ, Kobe, Hyogo 6578501, Japan. RI MOTOKI, Masakazu/B-4212-2009; OI Seo, Eun-Suk/0000-0001-8682-805X NR 48 TC 129 Z9 130 U1 2 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-6505 J9 ASTROPART PHYS JI Astropart Phys. PD NOV PY 2001 VL 16 IS 2 BP 121 EP 128 DI 10.1016/S0927-6505(01)00107-4 PG 8 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 476CB UT WOS:000171207700001 ER PT J AU Borgani, S Rosati, P Tozzi, P Stanford, SA Eisenhardt, PR Lidman, C Holden, B Della Ceca, R Norman, C Squires, G AF Borgani, S Rosati, P Tozzi, P Stanford, SA Eisenhardt, PR Lidman, C Holden, B Della Ceca, R Norman, C Squires, G TI Measuring Omega(m) with the ROSAT Deep Cluster Survey SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmological parameters; cosmology : theory; dark matter; galaxies : clusters : general X-rays : galaxies ID X-RAY-CLUSTERS; GALAXY CLUSTERS; HIGH-REDSHIFT; TEMPERATURE FUNCTION; COOLING FLOWS; EVOLUTION; MASS; CONSTRAINTS; LUMINOSITY; PARAMETERS AB We analyze the ROSAT Deep Cluster Survey (RDCS) to derive cosmological constraints from the evolution of the cluster X-ray luminosity distribution. The sample contains 103 galaxy clusters out to z similar or equal to 0.85 and flux limit F-lim = 3 x 10(-14) ergs s(-1) cm(-2) (RDCS-3) in the [0.5E2.0] keV energy band, with a high-redshift extension containing four clusters at 0.90 less than or equal to z less than or equal to 1.26 and brighter than F-lim = 1 x 10(-14) ergs s(-1) cm(-2) (RDCS-1). We assume cosmological models to be speciDed by the matter density parameter Omega (m), the rms fluctuation amplitude at the 8 h(-1) Mpc scale sigma (8), and the shape parameter for the cold dark matter-like power spectrum Gamma. Model predictions for the cluster mass function are converted into the X-ray luminosity function in two steps. First, we convert mass into intracluster gas temperature by assuming hydrostatic equilibrium. Then, temperature is converted into X-ray luminosity by using the most recent data on the L-X-T-X relation for nearby and distant clusters. These include the Chandra data for six distant clusters at 0.57 less than or equal to z less than or equal to 1.27. From RDCS-3 we find Omega (m) = 0.35(-0.10)(+0.13) and sigma (8) = 0.66(-0.05)(+0.06) for a spatially flat universe with a cosmological constant, with no significant constraint on Gamma (errors correspond to 1 sigma confidence levels for three fitting parameters). Even accounting for both theoretical and observational uncertainties in the mass-X-ray luminosity conversion, an Einstein-de Sitter model is always excluded at far more than the 3 sigma level. We also show that the number of X-ray-bright clusters in RDCS-1 at z >0.9 is expected from the evolution inferred at z <0.9 data. C1 Univ Trieste, Dipartimento Astron, Ist Nazl Fis Nucl, Sez Trieste, I-34100 Trieste, Italy. Univ Perugia, Dipartimento Fis, Ist Nazl Fis Nucl, Sez Perugia, I-06123 Perugia, Italy. European So Observ, D-85748 Garching, Germany. Osserv Astron Trieste, I-34131 Trieste, Italy. Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94551 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Osserv Astron Brera, I-20121 Milan, Italy. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. CALTECH, Dept Astron, Pasadena, CA 91125 USA. RP Borgani, S (reprint author), Univ Trieste, Dipartimento Astron, Ist Nazl Fis Nucl, Sez Trieste, Via Tiepolo 11, I-34100 Trieste, Italy. OI Borgani, Stefano/0000-0001-6151-6439 NR 68 TC 219 Z9 219 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 13 EP 21 DI 10.1086/323214 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600002 ER PT J AU Arav, N De Kool, M Korista, KT Crenshaw, DM Van Breugel, W Brotherton, M Green, RF Pettini, M Wills, B De Vries, W Becker, B Brandt, WN Green, P Junkkarinen, VT Koratkar, A Laor, A Laurent-Muehleisen, SA Mathur, S Murray, N AF Arav, N De Kool, M Korista, KT Crenshaw, DM Van Breugel, W Brotherton, M Green, RF Pettini, M Wills, B De Vries, W Becker, B Brandt, WN Green, P Junkkarinen, VT Koratkar, A Laor, A Laurent-Muehleisen, SA Mathur, S Murray, N TI HST STIS observations of PG 0946+301: The highest quality UV spectrum of a BALQSO SO ASTROPHYSICAL JOURNAL LA English DT Article DE quasars : absorption lines; quasars : individual (PG 0946+301); ultraviolet : galaxies ID BROAD ABSORPTION-LINE; QUASI-STELLAR OBJECTS; ACTIVE GALACTIC NUCLEI; RADIATIVE ACCELERATION; DISK WINDS; QSOS; PG-0946+301; OUTFLOWS; SPECTROGRAPH; ULTRAVIOLET AB We describe deep (40 orbits) Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of the broad absorption line (BAL) quasi-stellar object (QSO) PG 0946+301 and make them available to the community. These observations are the major part of a multiwavelength campaign on this object aimed at determining the ionization equilibrium and abundances (IEAs) in BALQSOs. We present simple template fits to the entire data set, which yield firm identifications for more than two dozen BALs from 18 ions and give lower limits for the ionic column densities. We find that the outflow's metallicity is consistent with being solar, while the abundance ratio of phosphorus to other metals is at least 10 times solar. These findings are based on diagnostics that are not sensitive to saturation and partial covering effects in the BALs, which considerably weakened previous claims for enhanced metallicity. Ample evidence for these effects is seen in the spectrum. We also discuss several options for extracting tighter IEA constraints in future analyses and present the significant temporal changes that are detected between these spectra and those taken by the HST Faint Object Spectrograph in 1992. C1 Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia. Western Michigan Univ, Dept Phys, Kalamazoo, MI 49008 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. Kitt Peak Natl Observ, Tucson, AZ 85726 USA. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. Univ Texas, Dept Astron, Austin, TX 78712 USA. Penn State Univ, Dept Astron & Astrophys, Davey Lab 105, University Pk, PA 16802 USA. Smithsonian Astrophys Observ, Hilo, HI 96721 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Technion Israel Inst Technol, Dept Phys, IL-32000 Haifa, Israel. Univ Toronto, Canadian Inst Theoret Astrophys, Toronto, ON M5S 3H8, Canada. RP Arav, N (reprint author), Univ Calif Berkeley, Dept Astron, 601 Campbell Hall 3411, Berkeley, CA 94720 USA. RI Brandt, William/N-2844-2015 OI Brandt, William/0000-0002-0167-2453 NR 39 TC 71 Z9 72 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 118 EP 130 DI 10.1086/323369 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600012 ER PT J AU Collier, S Crenshaw, DM Peterson, BM Brandt, WN Clavel, J Edelson, R George, IM Horne, K Kriss, GA Mathur, S Netzer, H O'Brien, PT Pogge, RW Pounds, KA Romano, P Shemmer, O Turner, TJ Wamsteker, W AF Collier, S Crenshaw, DM Peterson, BM Brandt, WN Clavel, J Edelson, R George, IM Horne, K Kriss, GA Mathur, S Netzer, H O'Brien, PT Pogge, RW Pounds, KA Romano, P Shemmer, O Turner, TJ Wamsteker, W TI Multiwavelength monitoring of the narrow-line Seyfert 1 galaxy Arakelian 564. II. Ultraviolet continuum and emission-line variability SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; galaxies : active; galaxies : individual (Arakelian 564); galaxies : nuclei; galaxies : Seyfert ID ACTIVE GALACTIC NUCLEI; X-RAY PROPERTIES; NGC 7469; ACCRETION DISCS; QUASARS; REGION; SPECTRA; SIZE; STEPS; ASCA C1 Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Greenbelt, MD 20771 USA. Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. ESA, Madrid 28080, Spain. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England. Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ St Andrews, Dept Phys & Astron, St Andrews KY16 9SS, Fife, Scotland. Univ Texas, Dept Astron, Austin, TX 78704 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Wise Observ, IL-69978 Tel Aviv, Israel. RP Collier, S (reprint author), Ohio State Univ, Dept Astron, 174 W 18th Ave, Columbus, OH 43210 USA. RI Brandt, William/N-2844-2015; OI Brandt, William/0000-0002-0167-2453; Romano, Patrizia/0000-0003-0258-7469 NR 67 TC 45 Z9 46 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 146 EP 161 DI 10.1086/323234 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600014 ER PT J AU Shemmer, O Romano, P Bertram, R Brinkmann, W Collier, S Crowley, KA Detsis, E Filippenko, AV Gaskell, CM George, TA Gliozzi, M Hiller, ME Jewell, TL Kaspi, S Klimek, ES Lannon, MH Li, W Martini, P Mathur, S Negoro, H Netzer, H Papadakis, I Papamastorakis, I Peterson, BM Peterson, BW Pogge, RW Pronik, VI Rumstay, KS Sergeev, SG Sergeeva, EA Stirpe, GM Taylor, CJ Treffers, RR Turner, TJ Uttley, P Vestergaard, M Von Braun, K Wagner, RM Zheng, Z AF Shemmer, O Romano, P Bertram, R Brinkmann, W Collier, S Crowley, KA Detsis, E Filippenko, AV Gaskell, CM George, TA Gliozzi, M Hiller, ME Jewell, TL Kaspi, S Klimek, ES Lannon, MH Li, W Martini, P Mathur, S Negoro, H Netzer, H Papadakis, I Papamastorakis, I Peterson, BM Peterson, BW Pogge, RW Pronik, VI Rumstay, KS Sergeev, SG Sergeeva, EA Stirpe, GM Taylor, CJ Treffers, RR Turner, TJ Uttley, P Vestergaard, M Von Braun, K Wagner, RM Zheng, Z TI Multiwavelength monitoring of the narrow-line Seyfert 1 galaxy Arakelian 564. III. Optical observations and the optical-UV-X-ray connection SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Arakelian 564); galaxies : nuclei; galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; INFRARED-EMISSION; NGC 3516; VARIABILITY; QUASARS; SPECTRA; ULTRAVIOLET AB We present the results of a 2 yr long optical monitoring program of the narrow-line Seyfert 1 galaxy Ark 564. The majority of this monitoring project was also covered by X-ray observations (RXT E), and for a period of similar to 50 days, we observed the galaxy in UV (HST) and X-rays (RXT E and ASCA) simultaneously with the ground-based observations. Rapid and large-amplitude variations seen in the X-ray band, on a daily and hourly timescale, were not detected at optical and UV wavelengths, which in turn exhibited much lower variability either on short (1 day) or long (several months) timescales. The only significant optical variations can be described as two 2-4 day events with similar to 10% flux variations. We detect no significant optical line variations and thus cannot infer a reverberation size for the broad-line region. Similarly, the large X-ray variations seem to vanish when the light curve is smoothed over a period of 30 days. The UV continuum follows the X-rays with a lag of similar to0.4 days, and the optical band lags the UV band by similar to2 days. No significant correlation was found between the entire X-ray data set and the optical band. Focusing on a 20 day interval around the strongest optical event we detect a significant X-ray-optical correlation with similar events seen in the UV and X-rays. Our data are consistent with reprocessing models on the grounds of the energy emitted in this single event. However, several large X-ray flares produced no corresponding optical emission. C1 Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Wise Observ, IL-69978 Tel Aviv, Israel. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. Univ Nebraska, Dept Phys & Astron, Lincoln, NE 68588 USA. Univ Crete, Dept Phys, Iraklion 71003, Greece. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. RIKEN, Cosm Radiat Lab, Wako, Saitama 35101, Japan. Crimean Astrophys Observ, UA-98409 Crimea, Ukraine. Isaac Newton Inst Chile, Crimean Branch, Crimea, Ukraine. Valdosta State Univ, Dept Phys Astron & Geosci, Valdosta, GA 31698 USA. Osservatorio Astron Bologna, I-40127 Bologna, Italy. Lawrenceville Sch, Lawrenceville, NJ 08648 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. RP Shemmer, O (reprint author), Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Sch Phys & Astron, IL-69978 Tel Aviv, Israel. EM ohad@wise.tau.ac.il; promano@astronomy.ohio-state.edu; rayb@as.arizona.edu; jhep@physics.uoc.gr; alex@astro.berkeley.edu; gaskell@unlserve.unl.edu; shai@wise.tau.ac.il; lannon@astronomy.ohio-state.edu; wli@astro.berkeley.edu; martini@ociw.edu; smita@astronomy.ohio-state.edu; netzer@wise.tau.ac.il; peterson@astronomy.ohio-state.edu; pogge@astronomy.ohio-state.edu; vpronik@crao.crimea.ua; krumstay@vladosta.edu; selena@crao.crimea.ua; sergeev@crao.crimea.ua; stirpe@bo.astro.it; ctaylor@lawrenceville.org; rtreffers@astro.berkeley.edu; turner@lucretia.gsfc.nasa.gov; pu@astro.soton.ac.uk; kaspar@astro.lsa.umich.edu; rmw@astronomy.ohio-state.edu; zhengz@astronomy.ohio-state.edu RI Papadakis, Iossif/C-3235-2011; Papamastorakis, Ioannis/G-7324-2011; Vestergaard, Marianne/M-5247-2014; Stirpe, Giovanna/O-9393-2015; OI Vestergaard, Marianne/0000-0001-9191-9837; Stirpe, Giovanna/0000-0002-3702-8731; Gaskell, C/0000-0003-4888-2009; Romano, Patrizia/0000-0003-0258-7469 NR 34 TC 54 Z9 57 U1 0 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 162 EP 170 DI 10.1086/323236 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600015 ER PT J AU Lee, BC Tucker, DL Vanden Berk, DE Yanny, B Reichart, DE Adelman, J Chen, B Harvanek, M Henden, A Ivezic, Z Kleinman, S Lamb, D Long, D McMillan, R Newman, PR Nitta, A Palunas, P Schneider, DP Snedden, S York, D Briggs, JW Brinkmann, J Csabai, I Hennessy, GS Kent, S Lupton, R Newberg, HJ Stoughton, C AF Lee, BC Tucker, DL Vanden Berk, DE Yanny, B Reichart, DE Adelman, J Chen, B Harvanek, M Henden, A Ivezic, Z Kleinman, S Lamb, D Long, D McMillan, R Newman, PR Nitta, A Palunas, P Schneider, DP Snedden, S York, D Briggs, JW Brinkmann, J Csabai, I Hennessy, GS Kent, S Lupton, R Newberg, HJ Stoughton, C TI Sloan Digital Sky Survey multicolor observations of GRB 010222 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID GAMMA-RAY BURST; OPTICAL-EMISSION; ABSORPTION; AFTERGLOWS; RADIATION; CURVES; SEARCH AB The discovery of an optical counterpart to GRB 010222 (detected by BeppoSAX) was announced 4.4 hr after the burst by Henden. The Sloan Digital Sky Survey's 0.5 m photometric telescope (PT) and 2.5 m survey telescope were used to observe the afterglow of GRB 010222 starting 4.8 hr after the gamma-ray burst. The 0.5 m PT observed the afterglow in five 300 s g*-band exposures over the course of half an hour, measuring a temporal decay rate in this short period of F(v) proportional to t(-1.0 +/-0.5). The 2.5 m camera imaged the counterpart nearly simultaneously in five filters (u*, g*, r*, i*, z*), with r* = 18.74 +/- 0.02 at 12:10 UT. These multicolor observations, corrected for reddening and the afterglow's temporal decay, are well-fitted by the power law F(v) proportional to v(-0.90 +/-0.03) with the exception of the u*-band UV flux which is 20% below this slope. We examine possible interpretations of this spectral shape, including source extinction in a star-forming region. C1 Fermilab Natl Accelerator Lab, Expt Astrophys Lab, Batavia, IL 60510 USA. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. European Space Agcy, XMM Sci Operat Ctr, Madrid 28080, Spain. Apache Point Observ, Sunspot, NM 88349 USA. Univ Space Res Assoc, USN Observ, Flagstaff Stn, Flagstaff, AZ 86002 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Catholic Univ Amer, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Yerkes Observ, Williams Bay, WI 53191 USA. Eotvos Lorand Univ, Dept Phys Complex Syst, H-1518 Budapest, Hungary. USN Observ, Washington, DC 20392 USA. Rensselaer Polytech Inst, Dept Phys, Troy, NY 12180 USA. RP Lee, BC (reprint author), Fermilab Natl Accelerator Lab, Expt Astrophys Lab, POB 500, Batavia, IL 60510 USA. EM bclee@fnal.gov; dtucker@fnal.gov; danvb@fnal.gov; yanny@fnal.gov; der@astro.caltech.edu; jen_a@fnal.gov; bchen@xmm.vilspa.esa.es; harvanek@aapo.nmsu.edu; aah@nofs.navy.mil; ivezic@astro.princeton.edu; sjk@apo.nmsu.edu; lamb@pion.uchicago.edu; long@apo.nmsu.edu; mcmillan@apo.nmsu.edu; prn@apo.nmsu.edu; ank@apo.nmsu.edu; palunas@etendue.gsfc.nasa.gov; dps@astro.psu.edu; snedden@apo.nmsu.edu; jwb@hale.yerkes.uchicago.edu; brinkmann@nmsu.edu; csabai@pha.jhu.edu; gsh@cygnus.usno.navy.mil; skent@fnal.gov; rhl@astro.princeton.edu; heidi@rpi.edu; stoughto@fnal.gov RI Csabai, Istvan/F-2455-2012; OI Csabai, Istvan/0000-0001-9232-9898 NR 42 TC 20 Z9 20 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 183 EP 188 DI 10.1086/322981 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600018 ER PT J AU Pence, WD Snowden, SL Mukai, K Kuntz, KD AF Pence, WD Snowden, SL Mukai, K Kuntz, KD TI Chandra X-ray sources in M101 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (M101); galaxies : spiral; X-rays : galaxies ID LARGE MAGELLANIC CLOUD; EXTERNAL GALAXIES; EMISSION; REGIONS; CAL-87; ROSAT; DISK; M81 AB A deep (98.2 ks) Chandra Cycle 1 observation has revealed a wealth of discrete X-ray sources as well as diffuse emission in the nearby face-on spiral galaxy M101. From this rich data set we have created a catalog of the 110 sources from the S3 chip detected with a significance of greater than 3 sigma. This detection threshold corresponds to a flux of similar to 10(-16) ergs cm(-2) s(-1) and a luminosity of similar to 10(36) ergs s(-1) for a distance to M101 of 7.2 Mpc. The sources display a distinct correlation with the spiral arms of M101 and include a variety of X-ray binaries, supersoft sources, supernova remnants, and other objects of which only similar to 27 are likely to be background sources. There are only a few sources in the interarm regions, and most of these have X-ray colors consistent with that of background active galactic nuclei. The derived log N-log S relation for the sources in M101 (background subtracted) has a slope of -0.80 +/- 0.05 over the range of 10(36)-10(38) ergs s(-1). The nucleus is resolved into two nearly identical X-ray sources, each with a 0.5-2.0 keV flux of 4 x 10(37) ergs s(-1). One of these sources coincides with the optical nucleus, and the other coincides with a cluster of stars 110 pc to the south. The field includes 54 optically identified supernova remnants (SNRs), of which 12 are detected by Chandra. Two of the SNR sources are variable and hence must be compact objects. In total, eight of the X-ray sources show evidence for short-term temporal variation during this observation. Two of these variable sources are now brighter than the ROSAT detection threshold, but they were not detected in the previous ROSAT observations taken in 1992 and 1996. There are also two variable sources previously seen with ROSAT that apparently have faded below the Chandra detection threshold. The brightest source in the field shows extreme long-term and short-term temporal variability. At its peak brightness it has a super-Eddington luminosity greater than 10(39) ergs s(-1). There are 10 supersoft sources (SSSs) in the field, which can be divided into two distinct subclasses : the brighter class (three objects) has a luminosity of similar to 10(38) ergs s(-1) and a blackbody temperature of similar to 70 eV, whereas the other class (seven objects) is an order of magnitude fainter and has a blackbody temperature of only similar to 50 eV. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. RP Pence, WD (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. RI Snowden, Steven/D-5292-2012 NR 31 TC 67 Z9 67 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 189 EP 202 DI 10.1086/323240 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600019 ER PT J AU Kraemer, KE Jackson, JM Deutsch, LK Kassis, M Hora, JL Fazio, GG Hoffmann, WF Dayal, A AF Kraemer, KE Jackson, JM Deutsch, LK Kassis, M Hora, JL Fazio, GG Hoffmann, WF Dayal, A TI Dust characteristics of massive star-forming sites in the mid-infrared SO ASTROPHYSICAL JOURNAL LA English DT Article DE HII regions; infrared : ISM; ISM : individual (W51 IRS 2, Monoceros R2, DR 21, S140); ISM : lines and bands; stars : formation ID H-II REGIONS; MIDINFRARED ARRAY CAMERA; MOLECULAR CLOUDS; RADIO-CONTINUUM; RADIATION TRANSFER; THERMAL EMISSION; ORION-KL; DR-21; MASER; W51 AB Four massive star-forming regions were imaged in the mid-infrared with the MIRAC3 instrument: W51 IRS 2, Mon R2, DR 21, and S140. We obtained high spatial resolution (similar to1") images at several wavelengths from 7.8 to 13.2 mum with the circular variable filter, as well as narrow-band continuum images at 12.5 and 20.6 mum toward each region. In each massive star-forming region, one or more sources show deep silicate absorption. For at least two of the massive star-forming regions, W51 IRS 2 and Mon R2, the absorbing material is highly localized and may be circumstellar material in disks or shells. The silicate absorption occurs at least as often around massive young stars as around young stars of lower mass (which are more often observed). The estimated optical depths of the silicate features are consistent with those predicted by radiative transfer models toward ultracompact H II regions, but substantially higher than observed toward T Tauri stars and other low-mass young stellar objects. There is no consistent correspondence between silicate absorption and either the dust color temperature or the 12.5 km opacity. In W51 IRS 2, the two previously known mid-infrared sources have been resolved into at least six subsources. Infrared counterparts are newly reported for two radio-continuum sources in S140. Also, new mid-infrared sources have been detected in both W51 IRS 2 and S140. We suggest that the infrared source in the southwest of DR 21 may not be self-luminous, but may instead be heated by the three nearby radio continuum sources. The gas density in the ring at Mon R2 supports the blister scenario for the IRS 1 H II region. C1 USAF, Res Lab, Space Vehicles Directorate, Hanscom AFB, MA 01731 USA. Boston Univ, Dept Astron, Boston, MA 02215 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. CALTECH, Jet Prop Lab, IPAC, Pasadena, CA 91125 USA. RP Kraemer, KE (reprint author), Boston Univ, Inst Astrophys Res, Boston, MA 02215 USA. OI Hora, Joseph/0000-0002-5599-4650; Kraemer, Kathleen/0000-0002-2626-7155 NR 75 TC 18 Z9 18 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 282 EP 298 DI 10.1086/323219 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600027 ER PT J AU Safi-Harb, S Harrus, IM Petre, R Pavlov, GG Koptsevich, AB Sanwal, D AF Safi-Harb, S Harrus, IM Petre, R Pavlov, GG Koptsevich, AB Sanwal, D TI X-ray observations of the supernova remnant G21.5-0.9 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (G21.5-0.9); stars : neutron; supernova remnants; X-rays : ISM ID RADIO PULSARS; 3C-58; LUMINOSITY; NEBULAE; SEARCH; STARS; MODEL; SHELL AB We present the analysis of archival X-ray observations of the supernova remnant (SNR) G21.5-0.9. Based on its morphology and spectral properties, G21.5-0.9 has been classified as a Crab-like SNR. For that reason, it was chosen as a Chandra calibration target. In their early analysis of part of these calibration data, Slane and coworkers discovered a low surface brightness, extended emission. They interpreted this component as the blast wave formed in the supernova explosion. XMM-Newton observations by Warwick and coworkers revealed the nonthermal nature of this emission, suggesting that it is instead an extension of the synchrotron nebula. In this paper, we revisit the Chandra analysis using new calibration data, improving the statistics by a factor of 2. We also include ROSAT and ASCA observations. Our analysis confirms the nonthermal nature of the extended emission. Advanced CCD Imaging Spectrometer images indicate that this component is not limb-brightened and that it shows knotty structures and a bright filament 2' north of the center. We find no evidence of line emission from any part of the remnant. We can reject a collisional equilibrium ionization thermal model at solar abundances and nonequilibrium ionization (NEI) models (such as a plane-parallel shock model with different ionization ages and constant temperature or an NEI model with a single ionization age and a constant temperature). The entire remnant is best fitted with a power-law model with a photon index steepening away from the center. The total unabsorbed flux F-x(0.5-10 keV) is 1.1 x 10(-10) ergs cm(-2) s(-1) with an 85% contribution from the 40" radius core. Timing analysis of the High-Resolution Camera data failed to detect any pulsations. We put a 16% upper limit on the pulsed fraction. We derive the physical parameters of the putative pulsar and compare them with those of other plerions (such as the Crab nebula and 3C 58). C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Penn State Univ, Davey Lab 525, University Pk, PA 16802 USA. Univ Manitoba, Winnipeg, MB R3T 2N2, Canada. RP Safi-Harb, S (reprint author), Univ Space Res Assoc, Columbia, MD 21044 USA. NR 34 TC 47 Z9 47 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 308 EP 320 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600029 ER PT J AU McIntosh, W Judge, PG AF McIntosh, W Judge, PG TI On the nature of magnetic shadows in the solar chromosphere SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : atmospheric motions; Sun : chromosphere; Sun : magnetic fields; Sun : transition region; Sun : UV radiation ID SUMER OBSERVATIONS; TRANSITION REGION; OSCILLATIONS; ATMOSPHERE AB Recent multi-instrument spacecraft studies of the solar photosphere and chromosphere have uncovered a feature-a "magnetic shadow" - not previously discussed in the literature. A region of the mid-chromosphere neighboring, but not within, a network magnetic element exhibits a suppression of both the mean UV line/continuum intensity and the characteristic 3 minute oscillation that is clearly observed elsewhere in apparently similar internetwork regions. The clearest cases appear to occur rarely, and their properties stand in obvious contrast to the well-known "aureoles" of enhanced variability seen surrounding some plage regions. It is imperative to understand more clearly the nature of the shadow region, not least because the suppressed atmospheric heating within it has implications for heating processes elsewhere in the chromosphere that are dependent on, or at least related to, the 3 minute oscillation. Based on the measured photospheric magnetic field, its upward extrapolation, and the appearance of spectral features formed above the midchromosphere, we suggest that a shadow occurs when magnetic structures, in a relatively weak background field, "close" locally within the chromosphere, suppressing the upward propagation of magnetoatmospheric waves into the chromosphere. C1 Natl Ctr Atmospher Res, High Altitude Observ, Boulder, CO 80307 USA. NASA, Goddard Space Flight Ctr, European Space Agcy, Dept Space Sci, Greenbelt, MD 20771 USA. RP Natl Ctr Atmospher Res, High Altitude Observ, POB 3000, Boulder, CO 80307 USA. EM scott@esa.nascom.nasa.gov; judge@hao.ucar.edu NR 19 TC 55 Z9 55 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 420 EP 426 DI 10.1086/323068 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600038 ER PT J AU Harrington, J Deming, D AF Harrington, J Deming, D TI Models of the Shoemaker-Levy 9 impacts. I. Ballistic Monte Carlo plume SO ASTROPHYSICAL JOURNAL LA English DT Article DE atmospheric effects; comets : individual (Shoemaker-Levy/9); hydrodynamics; infrared : solar system; planets and satellites : individual (Jupiter); shock waves ID COMET SHOEMAKER-LEVY-9; FRAGMENT-L; JUPITER; COLLISION; TEMPERATURE; ATMOSPHERE; MOTION; DEBRIS; SITES; SIZE AB We model the plumes raised by impacting fragments of comet Shoemaker-Levy 9 to calculate synthetic plume views, atmospheric infall fluxes, and debris patterns. Our plume is a swarm of ballistic particles with one of several mass-velocity distributions (MVDs). The swarm is ejected instantaneously and uniformly into a cone from its apex. On falling to the ejection altitude, particles slide with horizontal deceleration following one of several schemes. The model ignores hydrodynamic and Coriolis effects. Initial conditions come from observations of plume heights and calculated or estimated properties of impactors. We adjust the plume tilt, opening angle, and minimum velocity and choose MVDs and sliding schemes to create impact patterns that match observations. Our best match uses the power-law MVD from the numerical impact model of Zahnle & Mac Low, with velocity cutoffs at 4.5 and 11.8 km s(-1), a cone opening angle of 75 degrees, a cone tilt of 30 degrees from vertical, and a sliding constant deceleration of 1.74 m s(-2). A mathematically derived feature of Zahnle & Mac Low's published cumulative MVD is a thin shell of mass at the maximum velocity, corresponding to the former atmospheric shock front. This vanguard contains 22% of the mass and 45% of the energy of the plume and accounts for several previously unexplained observations, including the large, expanding ring seen at 3.2 mum by McGregor et al. and the "third precursors" and "flare" seen near 300 and 1000 s, respectively, in the infrared light curves. We present synthetic views of the plumes in flight and after landing and derive infall fluxes of mass, energy, and vertical momentum as a function of time and position on the surface. These fluxes initialize a radiative-hydrodynamic atmosphere model (Paper II of this series) that calculates the thermal and dynamical response of the atmosphere and produces synthetic light curves. C1 Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. RP Harrington, J (reprint author), Cornell Univ, Dept Astron, 326 Space Sci Bldg, Ithaca, NY 14853 USA. RI Harrington, Joseph/E-6250-2011 NR 35 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 455 EP 467 DI 10.1086/323210 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600043 ER PT J AU Deming, D Harrington, J AF Deming, D Harrington, J TI Models of the Shoemaker-Levy 9 impacts. II. Radiative-hydrodynamic modeling of the plume splashback SO ASTROPHYSICAL JOURNAL LA English DT Article DE atmospheric effects; comets : individual (Shoemaker-Levy/9); hydrodynamics; infrared : solar system; planets and satellites : individual (Jupiter); shock waves ID COMET SHOEMAKER-LEVY-9; R-IMPACT; FRAGMENT-L; PALOMAR OBSERVATIONS; LIGHT CURVES; JUPITER; COLLISION; SL9; TEMPERATURE; ATMOSPHERE AB We model the plume "splashback" phase of the Shoemaker-Levy 9 (SL9) collisions with Jupiter. We modified the ZEUS-3D hydrodynamic code to include radiative transport in the gray approximation and present validation tests. After initializing with a model Jovian atmosphere, we couple mass and momentum fluxes of SL9 plume material, as calculated by the ballistic Monte Carlo plume model of Paper I of this series. A strong and complex shock structure results. The shock temperatures produced by the model agree well with observations, and the structure and evolution of the modeled shocks account for the appearance of high-excitation molecular line emission after the peak of the continuum light curve. The splashback region cools by radial expansion as well as by radiation. The morphology of our synthetic continuum light curves agrees with observations over a broad wavelength range (0.9-12 mum). Much of the complex structure of these light curves is a natural consequence of the temperature dependence of the Planck function and the plume velocity distribution. A feature of our ballistic plume is a shell of mass at the highest velocities, which we term the "vanguard." Portions of the vanguard ejected on shallow trajectories produce a lateral shock front, whose initial expansion accounts for the "third precursors" seen in the 2 mum light curves of the larger impacts and for hot methane emission at early times observed by Dinelli and coworkers. Continued propagation of this lateral shock approximately reproduces the radii, propagation speed, and centroid positions of the large rings observed at 3-4 mum by McGregor and coworkers. The portion of the vanguard ejected closer to the vertical falls back with high z-component velocities just after maximum light, producing CO emission and the "flare" seen at 0.9 mum. The model also produces secondary maxima ("bounces"), whose amplitudes and periods are in agreement with observations. C1 NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. RP Deming, D (reprint author), NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Code 693, Greenbelt, MD 20771 USA. RI Harrington, Joseph/E-6250-2011 NR 54 TC 10 Z9 10 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP 468 EP 480 DI 10.1086/323209 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PC UT WOS:000171883600044 ER PT J AU Cottin, H Szopa, C Moore, MH AF Cottin, H Szopa, C Moore, MH TI Production of hexamethylenetetramine in photolyzed and irradiated interstellar cometary ice analogs SO ASTROPHYSICAL JOURNAL LA English DT Article DE astrochemistry; comets : general; ISM : molecules; methods : laboratory; space vehicles : instruments ID CRYOGENIC TEMPERATURES; CARBONIC-ACID; METHANOL; RELEVANT; FORMALDEHYDE; MOLECULES; SPECTRUM; MIXTURES; DIOXIDE; HALLEY AB We report hexamethylenetetramine (HMT) detection in organic residues resulting from H2O : CO : CH3OH : NH3 ices submitted to UV photolysis or proton irradiation. This is the first time HMT is detected after proton irradiation of an interstellar or cometary ice analog, whereas this molecule was suspected to be a characteristic signature of UV versus ion processing. This result strengthens the probability of HMT presence in the interstellar medium and in comets, where it may eventually be detected with the COSAC (COmetary Sampling And Composition) experiment on board the upcoming Rosetta mission. C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. Univ Paris 07, Lab Interuniv Syst Atmospher, CNRS, UMR 7583, F-94010 Creteil, France. Univ Paris 12, Lab Interuniv Syst Atmospher, CNRS, UMR 7583, F-94010 Creteil, France. RP Cottin, H (reprint author), NASA, Goddard Space Flight Ctr, Astrochem Branch, Code 691, Greenbelt, MD 20771 USA. RI Cottin, Herve/H-5654-2013; szopa, cyril/C-6865-2015 OI Cottin, Herve/0000-0001-9170-5265; szopa, cyril/0000-0002-0090-4056 NR 30 TC 45 Z9 45 U1 0 U2 7 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP L139 EP L142 DI 10.1086/324575 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PD UT WOS:000171883700033 ER PT J AU Lee, AT Ade, P Balbi, A Bock, J Borrill, J Boscaleri, A de Bernardis, P Ferreira, PG Hanany, S Hristov, VV Jaffe, AH Mauskopf, PD Netterfield, CB Pascale, E Rabii, B Richards, PL Smoot, GF Stompor, R Winant, CD Wu, JHP AF Lee, AT Ade, P Balbi, A Bock, J Borrill, J Boscaleri, A de Bernardis, P Ferreira, PG Hanany, S Hristov, VV Jaffe, AH Mauskopf, PD Netterfield, CB Pascale, E Rabii, B Richards, PL Smoot, GF Stompor, R Winant, CD Wu, JHP TI A high spatial resolution analysis of the MAXIMA-1 cosmic microwave background anisotropy data SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations ID RADIATION; UNIVERSE; FLAT AB We extend the analysis of the MAXIMA-1 cosmic microwave background data to smaller angular scales. MAXIMA, a bolometric balloon-borne experiment, mapped a 124 deg(2) region of the sky with 10' resolution at frequencies of 150, 240, and 410 GHz during its first flight. The original analysis, which covered the multipole range 36 less than or equal to l less than or equal to 785 using a 100 deg(2) map, is extended to l = 1235 using a subset of the data from three 150 GHz photometers in the fully cross-linked central 60 deg(2) of the map. The main improvement over the original analysis is the use of 3' square pixels in the calculation of the map. The new analysis is consistent with the original for l < 785. For l > 785, where inflationary models predict a third acoustic peak, the new analysis shows power with an amplitude of 56 +/- 7 muK at l similar or equal to 850 in excess to the average power of 42 +/- 3 muK in the range 441 < l < 785. C1 Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Div Phys, Berkeley, CA 94720 USA. Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. Univ London Queen Mary & Westfield Coll, London E1 4NS, England. Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Natl Energy Res Sci Comp Ctr, Berkeley, CA 94720 USA. CNR, IROE, I-50127 Florence, Italy. Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. Univ Oxford, Dept Astrophys, Oxford OX1 3RH, England. Inst Super Tecn, CENTRA, P-1096 Lisbon, Portugal. Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. Univ Wales Coll Cardiff, Dept Phys & Astron, Cardiff CF2 3YB, S Glam, Wales. Univ Toronto, Dept Phys & Astron, Toronto, ON M5S 1A1, Canada. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Copernicus Astron Ctr, PL-00716 Warsaw, Poland. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. RP Lee, AT (reprint author), Univ Calif Berkeley, Dept Phys, 366 Le Conte Hall, Berkeley, CA 94720 USA. RI Jaffe, Andrew/D-3526-2009; OI de Bernardis, Paolo/0000-0001-6547-6446; WU, JIUN-HUEI/0000-0001-9608-7662 NR 19 TC 303 Z9 305 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP L1 EP L5 DI 10.1086/324437 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PD UT WOS:000171883700001 ER PT J AU Sion, EM Cheng, FH Szkody, P Gansicke, B Sparks, WM Hubeny, I AF Sion, EM Cheng, FH Szkody, P Gansicke, B Sparks, WM Hubeny, I TI Hubble Space Telescope STIS spectroscopy of VW Hydri during early quiescence following a superoutburst SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; stars : abundances; stars : dwarf novae; stars : individual (VW Hydri); white dwarfs ID WHITE-DWARF; NOVA; ACCRETION; OUTBURST; MASS AB Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) observations of VW Hydri 2 and 7 days after the end of a superoutburst reveal a heated white dwarf with deep broad Ly alpha, narrow metallic absorption features and evidence of a hotter Keplerian-broadened component. We confirm the existence of enhanced abundances of odd-numbered nuclear species P, Mn, and Al as well as an N/C ratio indicative of CNO H-burning thermonuclear processing. Our best single-temperature white dwarf reduced chi (2) fit to the first spectrum reveals (1) a DAZQ white dwarf with T-eff = 22,500 +/- 500 K, log g = 8.0, and photospheric abundances C = 0.3 solar, N = 3.0 solar, O = 3.0 solar, Si = 0.3 solar, Al = 2 solar, Fe = 0.5 solar, Mg = 3.0 solar, Mn = 50 solar, Ni = 0.3 solar, P = 15 solar, and Ti = 0.1 solar. The best-fit white dwarf + accretion belt composite model yields a large improvement in the reduced chi (2) value. The accretion belt temperature is 32,000 K and covers a fractional area of 3%, contributing 11% of the flux. The second spectrum 5 days later reveals slightly increased metal abundances except that P is elevated to 20 times solar while Fe has declined to 0.05 times solar. The white dwarf has cooled by approximate to 1000 K, the belt temperature is 32,000 K, and the fractional area and flux contribution of the belt are 5% and 20%, respectively. These STIS observations confirm that a past (prehistoric?) thermonuclear runaway has occurred on the white dwarf in VW Hyi. It is expected that the thermonuclear runaway would be strong enough to produce a nova outburst. Therefore, these two classes of close binaries, namely, dwarf novae and classical novae, are linked and can overlap. C1 Villanova Univ, Dept Astron & Astrophys, Villanova, PA 19085 USA. Univ Sci & Technol China, Ctr Astrophys, Hefei 230026, Anhui, Peoples R China. Chinese Acad Sci, Natl Astron Observ, Beijing 100012, Peoples R China. Univ Washington, Dept Astron, Seattle, WA 98195 USA. Univ Gottingen, D-37083 Gottingen, Germany. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Sion, EM (reprint author), Villanova Univ, Dept Astron & Astrophys, Villanova, PA 19085 USA. RI Gaensicke, Boris/A-9421-2012 OI Gaensicke, Boris/0000-0002-2761-3005 NR 15 TC 19 Z9 19 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP L127 EP L130 DI 10.1086/324558 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PD UT WOS:000171883700030 ER PT J AU Stompor, R Abroe, M Ade, P Balbi, A Barbosa, D Bock, J Borrill, J Boscaleri, A de Bernardis, P Ferreira, PG Hanany, S Hristov, V Jaffe, AH Lee, AT Pascale, E Rabii, B Richards, PL Smoot, GF Winant, CD Wu, JHP AF Stompor, R Abroe, M Ade, P Balbi, A Barbosa, D Bock, J Borrill, J Boscaleri, A de Bernardis, P Ferreira, PG Hanany, S Hristov, V Jaffe, AH Lee, AT Pascale, E Rabii, B Richards, PL Smoot, GF Winant, CD Wu, JHP TI Cosmological implications of the MAXIMA-1 high-resolution cosmic microwave background anisotropy measurement SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations ID POWER SPECTRUM; UNIVERSE; CONSTANT; CONSTRAINTS; SUPERNOVAE; BOOMERANG AB We discuss the cosmological implications of the new constraints on the power spectrum of the cosmic microwave background (CMB) anisotropy derived from a new high-resolution analysis of the MAXIMA-1 measurement. The power spectrum indicates excess power at l similar to 860 over the average level of power at 411 less than or equal to l less than or equal to 785. This excess is statistically significant at the similar to 95% confidence level. Its position coincides with that of the third acoustic peak, as predicted by generic inflationary models selected to fit the first acoustic peak as observed in the data. The height of the excess power agrees with the predictions of a family of inflationary models with cosmological parameters that are fixed to fit the CMB data previously provided by BOOMERANG-LDB and MAXIMA-1 experiments. Our results therefore lend support for inflationary models and more generally for the dominance of adiabatic coherent perturbations in the structure formation of the universe. At the same time, they seem to disfavor a large variety of the nonstandard (but inflation-based) models that have been proposed to improve the quality of fits to the CMB data and the consistency with other cosmological observables. Within standard inflationary models, our results combined with the COBE/Differential Microwave Radiometer data give best-fit values and 95% confidence limits for the baryon density, Omega (b)h(2) similar or equal to 0.033 +/- 0.013, and the total density, Omega = 0.9(-0.16)(+0.18). The primordial spectrum slope (n(s)) and the optical depth to the last scattering surface (tau (c)) are found to be degenerate and to obey the relation n(s) similar or equal to (0.99 +/- 0.14) + 0.46 tau (c), for tau (c) less than or equal to 0.5 (all at 95% confidence levels). C1 Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Copernicus Astron Ctr, PL-00716 Warsaw, Poland. Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. Queen Mary Univ London, London E1 4NS, England. Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy. Univ Calif Berkeley, Lawrence Berkeley Lab, Div Phys, Berkeley, CA 94720 USA. Inst Super Tecn, CENTRA, P-1096 Lisbon, Portugal. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Natl Energy Res Sci Comp Ctr, Berkeley, CA 94720 USA. CNR, IROE, I-50127 Florence, Italy. Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. Univ Oxford, Dept Astrophys, Oxford OX1 3RH, England. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. RP Univ Calif Berkeley, Ctr Particle Astrophys, 301 Le Conte Hall, Berkeley, CA 94720 USA. RI Jaffe, Andrew/D-3526-2009; OI de Bernardis, Paolo/0000-0001-6547-6446; WU, JIUN-HUEI/0000-0001-9608-7662; Barbosa, Domingos/0000-0002-5191-7826 NR 30 TC 204 Z9 205 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP L7 EP L10 DI 10.1086/324438 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PD UT WOS:000171883700002 ER PT J AU White, NE Angelini, L AF White, NE Angelini, L TI The discovery of a second luminous low-mass X-ray binary in the globular cluster M15 SO ASTROPHYSICAL JOURNAL LA English DT Article DE globular clusters : individual (M15); stars : individual (AC 211); X-rays : binaries; X-rays : individual (4U 2127+119) ID PERIOD; SPECTROSCOPY; X-2127+119; PHOTOMETRY; BURST; CORE AB We report an observation by the Chandra X-Ray Observatory of 4U 2127+119, the X-ray source identified with the globular cluster M15. The Chandra observation reveals that 4U 2127+119 is in fact two bright sources, separated by 2."7. One source is associated with AC 211, the previously identified optical counterpart to 4U 2127+119, a low-mass X-ray binary (LMXB). The second source, M15 X-2, is coincident with a 19th U-magnitude blue star that is 3."3 from the cluster core. The Chandra count rate of M15 X-2 is 2.5 times higher than that of AC 211. Prior to the 0."5 imaging capability of Chandra, the presence of two so closely separated bright sources would not have been resolved. The optical counterpart, X-ray luminosity, and spectrum of M15 X-2 are consistent with it also being an LMXB system. This is the first time that two LMXBs have been seen to be simultaneously active in a globular cluster. The discovery of a second active LMXB in M15 solves a long-standing puzzle where the properties of AC 211 appear consistent with it being dominated by an extended accretion disk corona, and yet 4U 2127+119 also shows luminous X-ray bursts requiring that the neutron star be directly visible. The resolution of 4U 2127+119 into two sources suggests that the X-ray bursts did not come from AC 211 but rather from M15 X-2. We discuss the implications of this discovery for understanding the origin and evolution of LMXBs in globular clusters as well as X-ray observations of globular clusters in nearby galaxies. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. RP White, NE (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 30 TC 71 Z9 71 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2001 VL 561 IS 1 BP L101 EP L105 DI 10.1086/324561 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 487PD UT WOS:000171883700024 ER PT J AU Assad, C Hartmann, MJ Lewis, MA AF Assad, C Hartmann, MJ Lewis, MA TI Introduction to the special issue on biomorphic robotics SO AUTONOMOUS ROBOTS LA English DT Editorial Material C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Iguana Robot Inc, Mahomet, IL 61853 USA. RP Assad, C (reprint author), CALTECH, Jet Prop Lab, MS 303-300,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Hartmann, Mitra/A-8150-2008; Hartmann, Mitra/B-6766-2009 NR 4 TC 0 Z9 0 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0929-5593 J9 AUTON ROBOT JI Auton. Robot. PD NOV PY 2001 VL 11 IS 3 BP 195 EP 200 DI 10.1023/A:1012443219790 PG 6 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 485ZW UT WOS:000171794200001 ER PT J AU Kennedy, B Agazarian, H Cheng, Y Garrett, M Hickey, G Huntsberger, T Magnone, L Mahoney, C Meyer, A Knight, J AF Kennedy, B Agazarian, H Cheng, Y Garrett, M Hickey, G Huntsberger, T Magnone, L Mahoney, C Meyer, A Knight, J TI LEMUR: Legged excursion mechanical utility rover SO AUTONOMOUS ROBOTS LA English DT Article; Proceedings Paper CT NASA Workshop on Biomorphic Robotics CY AUG, 2000 CL CALIF INST TECHNOL, JET PROPULS LAB, PASADENA, CALIFORNIA SP NASA HO CALIF INST TECHNOL, JET PROPULS LAB DE robot; biomorphic; assembly; inspection; maintenance (AIM); robotic limb; Space Solar Power (SSP) AB Although future orbital facilities will have immense scale, details will require intricate operations in restrictive, confined quarters. LEMUR is a small, agile and capable six-legged walking robot that has been built at the Jet Propulsion Laboratory to perform dexterous small-scale assembly, inspection and maintenance. It is intended to expand the operational envelope of robots in its size class (sub-5 kg) through the flexible use of its limbs and effectors, as well as through the modular changeout of those effectors. In short, LEMUR is intended as a robotic instantiation of a six-limbed primate with Swiss Army knife tendencies. LEMUR's layout consists of six independently operated limbs arranged in two rows of three. The front two limbs have four active degrees of freedom while the rear four limbs have three each. Each limb is reconfigurable to allow the integration of a variety of mechanical tools. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kennedy, B (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 28 Z9 28 U1 0 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0929-5593 J9 AUTON ROBOT JI Auton. Robot. PD NOV PY 2001 VL 11 IS 3 BP 201 EP 205 DI 10.1023/A:1012474603861 PG 5 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 485ZW UT WOS:000171794200002 ER PT J AU Hartmann, MJ AF Hartmann, MJ TI Active sensing capabilities of the rat whisker system SO AUTONOMOUS ROBOTS LA English DT Article; Proceedings Paper CT NASA Workshop on Biomorphic Robotics CY AUG, 2000 CL CALIF INST TECHNOL, JET PROPULS LAB, PASADENA, CALIFORNIA SP NASA HO CALIF INST TECHNOL, JET PROPULS LAB DE vibrissae; exploratory behavior; exploration; tactile discrimination; active sensing; texture ID VIBRISSAL AB The rat whisker system may be a good model for approaching the design of robust robotic active sensing and exploratory systems. Here we examine how rats use their whiskers (vibrissae) during free exploratory behavior and during a texture discrimination task. Results show that during free exploration, the rat rhythmically moves its head to place its small (micro) vibrissae on the surfaces it is exploring. These periodic "microvibrissal placements" are temporally synchronized with the whisking movements of the large (macro) vibrissae. The periodic microvibrissal placements occurred even during a texture discrimination task, in which a smooth, continuous movement might have been equally effective at extracting the required information. Finally, it was found that rats may sometimes use their micro and macro vibrissae consecutively, instead of simultaneously. This suggests that, like humans, rats' exploration consists of a series of movement sequences in which increasingly refined information is gathered about an object. Some implications of these results for the design of artificial exploratory systems are discussed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hartmann, MJ (reprint author), CALTECH, Jet Prop Lab, MS 303-300,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Hartmann, Mitra/A-8150-2008; Hartmann, Mitra/B-6766-2009 NR 10 TC 52 Z9 53 U1 0 U2 6 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0929-5593 J9 AUTON ROBOT JI Auton. Robot. PD NOV PY 2001 VL 11 IS 3 BP 249 EP 254 DI 10.1023/A:1012439023425 PG 6 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 485ZW UT WOS:000171794200009 ER PT J AU Paulin, MG Hoffman, LF Assad, C AF Paulin, MG Hoffman, LF Assad, C TI A model of cerebellar computations for dynamical state estimation SO AUTONOMOUS ROBOTS LA English DT Article; Proceedings Paper CT NASA Workshop on Biomorphic Robotics CY AUG, 2000 CL CALIF INST TECHNOL, JET PROPULS LAB, PASADENA, CALIFORNIA SP NASA HO CALIF INST TECHNOL, JET PROPULS LAB DE cerebellum; state estimation; vestibular; neural simulation; motor control; vertebrate; receptive field; spike train; trajectory prediction; Kalman filter ID MOTOR CONTROL AB The cerebellum is a neural structure that is essential for agility in vertebrate movements. Its contribution to motor control appears to be due to a fundamental role in dynamical state estimation, which also underlies its role in various non-motor tasks. Single spikes in vestibular sensory neurons carry information about head state. We show how computations for optimal dynamical state estimation may be accomplished when signals are encoded in spikes. This provides a novel way to design dynamical state estimators, and a novel way to interpret the structure and function of the cerebellum. C1 Univ Otago, Dept Zool, Dunedin, New Zealand. Univ Otago, Ctr Neurosci, Dunedin, New Zealand. Univ Calif Los Angeles, Sch Med, Div Head & Neck Surg, Los Angeles, CA 90024 USA. NASA, Ames Res Ctr, Vestibular Res Facil, Mt View, CA USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Paulin, MG (reprint author), Univ Otago, Dept Zool, POB 56, Dunedin, New Zealand. NR 25 TC 10 Z9 10 U1 1 U2 6 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0929-5593 J9 AUTON ROBOT JI Auton. Robot. PD NOV PY 2001 VL 11 IS 3 BP 279 EP 284 DI 10.1023/A:1012499209312 PG 6 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 485ZW UT WOS:000171794200014 PM 12238519 ER PT J AU Assad, C AF Assad, C TI An hypothesis for a novel learning mechanism in the cerebellar cortex SO AUTONOMOUS ROBOTS LA English DT Article; Proceedings Paper CT NASA Workshop on Biomorphic Robotics CY AUG, 2000 CL CALIF INST TECHNOL, JET PROPULS LAB, PASADENA, CALIFORNIA SP NASA HO CALIF INST TECHNOL, JET PROPULS LAB DE cerebellum; granule cell ascending branch; Hebbian learning; dynamic state prediction ID MOTOR CONTROL; GRANULE CELL; SYSTEM; MODELS AB The cerebellar cortical circuitry may support a distinct second form of associative learning, complementary to the well-known synaptic plasticity (long term depression, LTD) that has been previously shown. As the granule cell axons ascend to the molecular layer, they make multiple synapses on the overlying Purkinje cells (PC). This ascending branch (AB) input, which has been ignored in models of cerebellar learning, is likely to be functionally distinct from the parallel fiber (PF) synaptic input. We predict that AB-PF correlations lead to Hebbian-type learning at the PF-PC synapse, including long term potentiation (LTP), and allowing the cortical circuit to combine AB-PF LTP for feedforward state prediction with climbing fiber LTD for feedback error correction. The new learning mechanism could therefore add computational capacity to cerebellar models and may explain more of the experimental data. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Assad, C (reprint author), CALTECH, Jet Prop Lab, MS 303-300,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 25 TC 4 Z9 4 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0929-5593 J9 AUTON ROBOT JI Auton. Robot. PD NOV PY 2001 VL 11 IS 3 BP 285 EP 290 DI 10.1023/A:1012451326151 PG 6 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 485ZW UT WOS:000171794200015 ER PT J AU Tunstel, E AF Tunstel, E TI Ethology as an inspiration for adaptive behavior synthesis in autonomous planetary rovers SO AUTONOMOUS ROBOTS LA English DT Article; Proceedings Paper CT NASA Workshop on Biomorphic Robotics CY AUG, 2000 CL CALIF INST TECHNOL, JET PROPULS LAB, PASADENA, CALIFORNIA SP NASA HO CALIF INST TECHNOL, JET PROPULS LAB DE planetary rover; mobile robots; ethology; adaptive behavior AB A navigation and control approach that supports adaptive behavior in rovers is presented. It is motivated by ethological models that suggest hierarchical organizations of behavior. The methodology employs fuzzy logic as a means to emulate animal behavior control mechanisms such as behavior activation levels, multi-behavior modulation, and threshold activation. The paper describes how these concepts can be tailored for autonomous navigation to provide a suitable framework for situated adaptation in rover control algorithms. In addition, an interesting characteristic of observed behavioral interactions achieved by an implementation of the approach is discussed, which is analogous to phenomena observed in measurements of animal brain activity during transitions between distinct behaviors. C1 CALTECH, Jet Prop Lab, Robot Vehicles Grp, Pasadena, CA 91109 USA. RP Tunstel, E (reprint author), CALTECH, Jet Prop Lab, Robot Vehicles Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 19 TC 14 Z9 15 U1 0 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0929-5593 J9 AUTON ROBOT JI Auton. Robot. PD NOV PY 2001 VL 11 IS 3 BP 333 EP 339 DI 10.1023/A:1012415812947 PG 7 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 485ZW UT WOS:000171794200022 ER PT J AU Huntsberger, T AF Huntsberger, T TI Biologically inspired autonomous rover control SO AUTONOMOUS ROBOTS LA English DT Article; Proceedings Paper CT NASA Workshop on Biomorphic Robotics CY AUG, 2000 CL CALIF INST TECHNOL, JET PROPULS LAB, PASADENA, CALIFORNIA SP NASA HO CALIF INST TECHNOL, JET PROPULS LAB DE biologically inspired control; action selection mechanisms; mobile robots ID ACTION SELECTION; NAVIGATION; BEHAVIOR; COLONY; ROBOTS AB Robotic missions beyond 2013 will likely be precursors to a manned habitat deployment on Mars. Such missions require robust control systems for long duration activities. Current single rover missions will evolve into deployment of multiple, heterogeneous cooperating robotic colonies. This paper describes the map-making memory and action selection mechanism of BISMARC (\underline Biologically \underline Inspired \underline System for \underline Map-based \underline Autonomous \underline Rover \underline Control) that is currently under development at the Jet Propulsion Laboratory in Pasadena, CA (Huntsberger and Rose, Neutral Networks, 11(7/8):1497-1510). BISMARC is an integrated control system for long duration missions involving robots performing cooperative tasks. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Huntsberger, T (reprint author), CALTECH, Jet Prop Lab, MS 82-105,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 25 TC 13 Z9 13 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0929-5593 J9 AUTON ROBOT JI Auton. Robot. PD NOV PY 2001 VL 11 IS 3 BP 341 EP 346 DI 10.1023/A:1012467829785 PG 6 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 485ZW UT WOS:000171794200023 ER PT J AU Clark, JB Riley, TL AF Clark, JB Riley, TL TI Screening EEG in aircrew selection: Clinical aerospace neurology perspective SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Editorial Material AB A Note from the Editor: The previous article by Hendriksen and Elderson (Aviat Space Environ Med 2001; 72:1025-33) on the use of electroencephalography in the assessment of aircrew fitness will likely generate appropriate and well-considered viewpoints from readers. Owing to the nature of the subject matter and importance of neurological examination in aircrew selection, I asked two experienced and well-respected clinicians, reviewers, and editorial board members to write a commentary on the article. It is the intent of this journal to present a balanced approach to clinical issues, recognizing that different perspectives do exist on most subjects. The reader should review all pertinent information and viewpoints in order to form an opinion on the issue. C1 NASA, Lyndon B Johnson Space Ctr, Flight Med Clin, Houston, TX 77058 USA. Baylor Coll Med, Houston, TX 77030 USA. RP Clark, JB (reprint author), NASA, Lyndon B Johnson Space Ctr, Flight Med Clin, Houston, TX 77058 USA. OI Clark, Jonathan/0000-0002-1162-1238 NR 12 TC 2 Z9 2 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 2001 VL 72 IS 11 BP 1034 EP 1036 PG 3 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 488WT UT WOS:000171960400009 PM 11718508 ER PT J AU Caplan, G AF Caplan, G TI Role of medical personnel and medical systems for international space station, and beyond SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Editorial Material C1 Univ Utah, Rocky Mtn Ctr Occupat & Environm Htl, Salt Lake City, UT 84112 USA. NASA, Kennedy Space Ctr, FL 32899 USA. RP Caplan, G (reprint author), Univ Utah, Rocky Mtn Ctr Occupat & Environm Htl, Salt Lake City, UT 84112 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 2001 VL 72 IS 11 BP 1058 EP 1058 PG 1 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 488WT UT WOS:000171960400016 PM 11718514 ER PT J AU Phinney, WC Halls, HC AF Phinney, WC Halls, HC TI Petrogenesis of the Early Proterozoic Matachewan dyke swarm, Canada, and implications for magma emplacement and subsequent deformation SO CANADIAN JOURNAL OF EARTH SCIENCES LA English DT Article ID KAPUSKASING STRUCTURAL ZONE; HEARST DIKE SWARM; SUPERIOR-PROVINCE; MUNRO-TOWNSHIP; PRECAMBRIAN DYKES; TRACE-ELEMENT; 2.45 GA; ONTARIO; PALEOMAGNETISM; CONSTRAINTS AB Major, minor, and rare-earth element analyses of fine-grained marginal material from 249 dykes of the Matachewan giant radiating swami show that the range in compositions cannot be produced by any simple fractionation model. Instead a two-stage process is required, whereby melts were modified by both fractionation and assimilation of lower crustal material, before rising and ponding at shallower crustal levels (15-20 km maximum), where a combination of fractional crystallization, plagioclase phenocryst formation, and periodic melt replenishment took place. These shallow crustal chambers acted as feeders for the numerous dykes. One hypothesis compatible with these observations involves an extensive rising plume that would provide heterogeneous melts over a large area accompanied by stresses that could produce a radial pattern of dykes. In a search for indications of lateral magma flow, a comparison of longitudinal variations in composition along four sample traverses across the western subswarm showed no truly consistent trends. However, Hf/Zr values are highest in the traverse nearest the focal region and lowest in the traverse 250 kin away, suggesting a change in magma composition with distance from the focus of the swarm, the assumed plume centre. Given the presently available data, the variations cannot be attributed to progressive fractionation during lateral magma flow in the crust nor to a northward increase in amounts of contamination by known lower crustal assimilants, all of which have Hf/Zr ratios higher than the distal values recorded by the dykes. Instead the variations are thought to reflect a possible compositional zonation of the plume head. The distortion of the western subswarm from a simple radiating pattern may have been facilitated by a low viscosity lower crust, softened by Matachewan igneous activity, and is consistent with deformation by the Blezardian orogen at about 2.2-2.4 Ga. C1 Univ Toronto, Dept Geol, Mississauga, ON L5L 1C6, Canada. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Halls, HC (reprint author), Univ Toronto, Dept Geol, 3359 Mississauga Rd, Mississauga, ON L5L 1C6, Canada. EM hhalls@utm.utoronto.ca NR 56 TC 19 Z9 21 U1 0 U2 4 PU CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS PI OTTAWA PA 1200 MONTREAL ROAD, BUILDING M-55, OTTAWA, ON K1A 0R6, CANADA SN 0008-4077 EI 1480-3313 J9 CAN J EARTH SCI JI Can. J. Earth Sci. PD NOV PY 2001 VL 38 IS 11 BP 1541 EP 1563 DI 10.1139/e01-044 PG 23 WC Geosciences, Multidisciplinary SC Geology GA 494DD UT WOS:000172265500004 ER PT J AU Banger, KK Cowen, J Hepp, AF AF Banger, KK Cowen, J Hepp, AF TI Synthesis and characterization of the first liquid single-source precursors for the deposition of ternary chalcopyrite (CuInS2) thin film materials SO CHEMISTRY OF MATERIALS LA English DT Article ID CVD; SE AB Molecular engineering of ternary single-source precursors based on the [{PBu3}(2)Cu(SR')(2)In-(SR')(2)] architecture have afforded the first liquid CIS ternary single-source precursors (when R = Et, n-Pr), which are suitable for low-temperature deposition (< 350 degreesC). Thermogravimetric analyses (TGA) and modulated DSC confirm their liquid phase and reduced stability. X-ray diffraction studies, EDS, and SEM support the formation of the single-phase chalcopyrite CuInS2 at low temperatures. C1 NASA, Glenn Res Ctr, Photovolta & Space Environm Branch, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH 44142 USA. Cleveland State Univ, Dept Chem, Cleveland, OH 44115 USA. RP Hepp, AF (reprint author), NASA, Glenn Res Ctr, Photovolta & Space Environm Branch, Cleveland, OH 44135 USA. NR 22 TC 53 Z9 53 U1 1 U2 8 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0897-4756 J9 CHEM MATER JI Chem. Mat. PD NOV PY 2001 VL 13 IS 11 BP 3827 EP + DI 10.1021/cm010507o PG 4 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 495CY UT WOS:000172323700007 ER PT J AU Tuttle, J Shirron, P DiPirro, M Jackson, M Behr, J Kamiya, K Warner, B Kunes, E Hait, T AF Tuttle, J Shirron, P DiPirro, M Jackson, M Behr, J Kamiya, K Warner, B Kunes, E Hait, T TI The HAWC and SAFIRE adiabatic demagnetization refrigerators SO CRYOGENICS LA English DT Article DE adiabatic demagnetization refrigerator; magnetic cooling; titanium 15-3-3-3 AB High-resolution airborne wide-band camera (HAWC) and sub-millimeter and Car-infrared experiment (SAFIRE) are far-infrared experiments which will fly on the stratospheric observator for infrared astronomer (SOFIA) aircraft. HAWC's detectors will operate at 0.2 K. while those of SAFIRE will be at 0.1 K. Each instrument will include an adiabatic demagnetization refrigerator (ADR) to cool its detector stage from the liquid helium bath temperature (HAWC's at 4 2 K and SAFIRE's pumped to about 1.3 K) to its operating temperature. Except for the Magnets used to achieve the cooling, the magnetic shielding, arid a slight difference in the heat switch design, the two ADRs are identical. We describe the ADR design arid present the results of performance testing. Published by Elsevier Science Ltd. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Tuttle, J (reprint author), NASA, Goddard Space Flight Ctr, Code 552, Greenbelt, MD 20771 USA. NR 5 TC 5 Z9 5 U1 0 U2 2 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD NOV-DEC PY 2001 VL 41 IS 11-12 BP 781 EP 787 AR PII S0011-2275(01)00169-2 DI 10.1016/S0011-2275(01)00169-2 PG 7 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 571NQ UT WOS:000176723800002 ER PT J AU Shirron, P Canavan, E DiPirro, M Jackson, M King, T Panek, J Tuttle, J AF Shirron, P Canavan, E DiPirro, M Jackson, M King, T Panek, J Tuttle, J TI A compact, high-performance continuous magnetic refrigerator for space missions SO CRYOGENICS LA English DT Article DE adiabatic demagnetization; low temperature; magnetic refrigeration; continuous AB We present test results of the first adiabatic demagnetization refrigerator (ADR) that produce true continuous cooling at sub-kelvin temperatures. This system uses multi le stages that operate in sequence to cascade heat from a "continuous" stage up to a heat sink. Continuous operation avoids the usual constraints of long hold times and short recycle times that lead to the generally large mass of single-shot ADRs, and allows us to achieve much higher cooling power per unit mass. Our design goal is 10 muW of cooling at 50 mK while rejecting heat to a 6 - 10 K heat sink. The total cold mass is estimated to be less than 10 kg, including magnetic shielding of each stage. These parameters envelop the requirements for currently planned astronomy missions. The relatively high temperature heat rejection capability allows it to operate,kith a mechanical cryocooler as part of a cryogen-free, low temperature cooling system. This has the advantages of long mission life and reduced complexity and cost. At present, we have assembled a three-stage ADR that operates with a superfluid helium bath. Additional work is underway to develop magnetocaloric materials that can extend its heat rejection capability up to 10 K. Design, operation and performance of the ADR are discussed. (C) 2002 Published by Elsevier Science Ltd. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Shirron, P (reprint author), NASA, Goddard Space Flight Ctr, Code 552, Greenbelt, MD 20771 USA. NR 12 TC 5 Z9 6 U1 1 U2 3 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD NOV-DEC PY 2001 VL 41 IS 11-12 BP 789 EP 795 AR PII S0011-2275(01)00164-3 DI 10.1016/S0011-2275(01)00164-3 PG 7 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 571NQ UT WOS:000176723800003 ER PT J AU Van Dresar, NT Siegwarth, JD Hasan, MM AF Van Dresar, NT Siegwarth, JD Hasan, MM TI Convective heat transfer coefficients for near-horizontal two-phase flow of nitrogen and hydrogen at low mass and heat flux SO CRYOGENICS LA English DT Article DE space cryogenics; heat transfer; two-phase flow ID GENERAL CORRELATION AB Correlations for convective heat transfer coefficients are reported for two-phase flow of nitrogen and hydrogen under low mass and heat flux conditions. The range of flowrates, heat flux and tube diameter are representative of thermodynamic vent systems (TVSs) planned for propellant tank pressure control in spacecraft operating over long durations in microgravity environments. Experiments were conducted in normal gravity with a 1.5degrees upflow configuration. The Nusselt number exhibits peak values near transition from laminar to turbulent flow based on the vapor Reynolds number. This transition closely coincides with a flow pattern transition front plug to slug flow. The Nusselt number was correlated using components of the Martinelli parameter and a liquid-only Froude number. Separate correlating equations were fitted to the laminar liquid/laminar vapor and laminar liquid/turbulent vapor flow data. The correlations give root-mean-squared (rms) prediction errors within 15%. Published by Elsevier Science Ltd. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Natl Inst Stand & Technol, Boulder, CO 80303 USA. RP Van Dresar, NT (reprint author), NASA, Glenn Res Ctr, MS 86-2, Cleveland, OH 44135 USA. NR 12 TC 5 Z9 5 U1 0 U2 7 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD NOV-DEC PY 2001 VL 41 IS 11-12 BP 805 EP 811 AR PII S0011-2275(01)00173-4 DI 10.1016/S0011-2275(01)00173-4 PG 7 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 571NQ UT WOS:000176723800005 ER PT J AU Weilert, M Hahn, I Barmatz, M Higham, D Frodsham, G AF Weilert, M Hahn, I Barmatz, M Higham, D Frodsham, G TI Progress on a small multi-cycling cryogenic fluid flow valve SO CRYOGENICS LA English DT Article DE space cryogenics; cryogenic bakes; MISTE ID LAMBDA-POINT; HELIUM; HEAT AB Mission Research corporation (MRC) in cooperation with the Jet Propulsion Laboratory (JPL) has developed a new small remote-controlled fluid valve. The motivation for developing this valve came from the requirements of a future International Space Station experiment called Microgravity Scaling Theory Experiment (MISTE). This experiment requires an in situ, low-temperature operated, fluid valve that can be open/closed over 50 times during a 4.5 month flight. The successful operation of MISTE and other space-based and ground-based laboratory experiments now in development will require reliable cryogenic fluid valves that are remotely operated, helium leak tight, non-magnetic, very low power, and which have a small dead volume. The new valve is normally closed and requires fluid actuation at a pressure of approximately 600 kPa to open. The heart of the valve design is found in the cnfiguration of the valve seat and sealing poppet. The design of these two surfaces was derived from work performed previously during a five year development program for a larger MRC remote-controlled, cryogenic fluid flow control valve. More than 50 of the larger valves have been produced and delivered for space flight applications. The new small valve has only three moving parts, which move less than 0.012 cm when the valve fully opens or closes. The bearing surfaces in the valve operating mechanism are all flexure (except for the valve poppet) and thus the valve is expected to have a lifetime of thousands of open/close cycles. The materials and processed used to fabricate the new valve have been flight certified. Results from the first extensively tested prototype show repeatable behaviour with a leak rete of typically 3 x 10(-8) scc/s after the first open/close cycle at 4.2 K, rising to about 10(-6) scc/s after 100 cycles. Further tests and minor modifications are expected to improve the performance. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Mission Res Corp, Logan, UT USA. RP Weilert, M (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. NR 8 TC 2 Z9 2 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD NOV-DEC PY 2001 VL 41 IS 11-12 BP 813 EP 816 AR PII S0011-2275(01)00172-2 DI 10.1016/S0011-2275(01)00172-2 PG 4 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 571NQ UT WOS:000176723800006 ER PT J AU Hastings, LJ Plachta, DW Salerno, L Kittel, P AF Hastings, LJ Plachta, DW Salerno, L Kittel, P TI An overview of NASA efforts on zero boiloff storage of cryogenic propellants SO CRYOGENICS LA English DT Article AB Extended cryogenic propellant storage periods have become increasingly important within NASA. Furthermore, cryocooler and passive insulation technology advances have substantially improved the prospects for zero boiloff (ZBO) storage of cryogenics. Accordingly. a cooperative effort by NASA's Ames Research Center, Glenn Research Center. and Marshall Space Flight Center has been implemented to develop ZBO concepts for in-space storage of cryogenic propellants. Accomplishments include analytical modeling an early subscale liquid hydrogen (LH2) demonstration: a flight-like 10 W, 95 K pulse tube cryocooler: and assembly of a large-scale test article for an LH2 system-level demonstration. Future testing with flight-like cryocoolers is planned. Published by Elsevier Science Ltd. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NASA, Glenn Res Ctr, Cleveland, OH USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Hastings, LJ (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 10 TC 11 Z9 13 U1 0 U2 4 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD NOV-DEC PY 2001 VL 41 IS 11-12 BP 833 EP 839 AR PII S0011-2275(01)00176-X DI 10.1016/S0011-2275(01)00176-X PG 7 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 571NQ UT WOS:000176723800009 ER PT J AU Kittel, P AF Kittel, P TI Propellant preservation using re-liquefiers SO CRYOGENICS LA English DT Article DE zero boiloff; space cryogenics; long-term storage AB The long-term storage of cryogenic propellants in space requires the use of active cooling. Previous work has considered using closed cycle coolers to exactly balance the parasitic heat loads on the propellant. An alternative approach using a re-liquefier has been suggested. This paper considers some of the advantages and disadvantages of this approach. A re-liquefier uses the propellant vapor as the working fluid. This may eliminate the need for a mixer in the propellant tank: may reduce the effect of leaks in the cooler: and may allow a more graceful way to accommodate cooler failure. However, the re-liquefier is unlikely to be operating at its optimal operating point: and will require some means of controlling contamination. Published by Elsevier Science Ltd. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kittel, P (reprint author), NASA, Ames Res Ctr, M-S 244-10, Moffett Field, CA 94035 USA. NR 10 TC 3 Z9 3 U1 0 U2 1 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD NOV-DEC PY 2001 VL 41 IS 11-12 BP 841 EP 844 AR PII S0011-2275(01)00165-5 DI 10.1016/S0011-2275(01)00165-5 PG 4 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 571NQ UT WOS:000176723800010 ER PT J AU Holmes, W Cho, H Hahn, I Larson, M Schweickart, R Volz, S AF Holmes, W Cho, H Hahn, I Larson, M Schweickart, R Volz, S TI Performance comparisons of space borne cryostats SO CRYOGENICS LA English DT Article DE space cryogenics; solid neon; solid hydrogen; liquid helium ID MISSION; DEWAR; BEHAVIOR AB We discuss the performance of liquid helium cryostats that have flown in space or are planned for space flight. Usual figures of merit are total cryostat mass or depletion rate of the cryogen. These often fail to accurately represent other important characteristics which affect cryostat performance such as the method used to survive launch lock-up or the temperature of the cryostat vacuum shell obtained by radiative cooling. To address these issues, we define the ratio, H/R in W day/l as metric to judge cryostat performance. The parameter H = sigma(B)A(tank)(T-shell(4) - T-tank(4)) is the Stefan Boltzmann law for energy transfer to the helium tank, where sigma(B) is the Stefan Boltzmann constant, A(tank) is the surface area of the cryogen tank and T-shell and T-tank are the vacuum shell and cryogen temperatures. The average cryogen depletion rate R = V-1/t is computed using the total cryogen volume. V-1, at the last fill before launch, including the volume of 'booster tank' cryogen if used arid the cryogen lifetime, t, to depletion on-orbit. Cryostats launched on the Space Shuttle have the same H/R approximate to 60 W day/l whether the cryogen was liquid helium or solid neon, and for a broad range of vacuum Shell temperatures 113 < T-shell < 300 K, cryogen volumes 2200 > V-1 > 85.1, and mission times, 9 days to > 2 years. Cryostats launched on unmanned rockets have a higher H/R approximate to 300 W day/l. Only one, the X-Ray Spectrometer (XRS), out of the four solid neon and two solid hydrogen cryostats showed a clear advantage of using a cryogen other than liquid helium. (C) 2002 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91106 USA. Ball Aerosp & Technol Corp, Boulder, CO 80301 USA. RP Holmes, W (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91106 USA. NR 26 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD NOV-DEC PY 2001 VL 41 IS 11-12 BP 865 EP 870 AR PII S0011-2275(01)00168-0 DI 10.1016/S0011-2275(01)00168-0 PG 6 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA 571NQ UT WOS:000176723800013 ER PT J AU Schulte, MD Shock, EL Wood, RH AF Schulte, MD Shock, EL Wood, RH TI The temperature dependence of the standard-state thermodynamic properties of aqueous nonelectrolytes SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Review ID PARTIAL MOLAL PROPERTIES; METAL-ORGANIC COMPLEXES; SODIUM-CHLORIDE SOLUTIONS; HIGH-PRESSURES; TRANSPORT-PROPERTIES; INFINITE DILUTION; HEAT-CAPACITIES; ELEVATED-TEMPERATURES; GEOCHEMICAL PROCESSES; WIDE RANGES AB Recent experimental studies of the standard-state heat capacities of aqueous nonelectrolytes at high temperatures make it possible to test predictions made with theoretical equations of state and correlation algorithms. Existing predictive methods are qualitatively correct and produce quantitative results that are in reasonable agreement with the new experimental data at temperature less than or equal to 350 degreesC, but much better results are possible using new data. Regression of the new data for CO2(aq), H2S(aq), CH4(aq), NH3(aq), and SO2(aq) leads to revised parameters for the revised Helgeson-Kirkham-Flowers (HKF) equation of state. New correlations based on these parameters allow revised regressions of older data for Xe(aq), Ar(aq), and C2H4(aq) and lead to new predictions for several other aqueous nonelectrolytes. These predictions are tested against experimentally determined equilibrium constants for reactions involving several other aqueous nonelectrolytes, including He(aq), Ne(aq), Kr(aq), Rn(aq), H-2(aq), N-2(aq), O-2(aq), and CO(aq). The correlations developed are used to make predictions for a variety of other aqueous nonelectrolytes, allowing incorporation of these species into models of geochemical processes. Copyright (C) 2001 Elsevier Science Ltd. C1 Univ Delaware, Ctr Mol & Engn Thermodynam, Dept Chem & Biochem, Newark, DE 19716 USA. Washington Univ, Dept Earth & Planetary Sci, GEOPIG, St Louis, MO 63130 USA. RP Schulte, MD (reprint author), NASA, Ames Res Ctr, MS 239-4, Moffett Field, CA 94035 USA. NR 110 TC 43 Z9 43 U1 0 U2 14 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD NOV PY 2001 VL 65 IS 21 BP 3919 EP 3930 DI 10.1016/S0016-7037(01)00717-7 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 493LY UT WOS:000172225600017 ER PT J AU Peltzer, G Crampe, F Hensley, S Rosen, P AF Peltzer, G Crampe, F Hensley, S Rosen, P TI Transient strain accumulation and fault interaction in the Eastern California shear zone SO GEOLOGY LA English DT Article DE strain transient; synthetic aperture radar interferometry; Eastern California shear zone ID LANDERS EARTHQUAKE SEQUENCE; CENTRAL GARLOCK FAULT; SOUTHERN-CALIFORNIA; MOJAVE DESERT; 1992 LANDERS; PLATE MOTION; SLIP RATE; DEFORMATION; PACIFIC; FIELD AB Satellite synthetic aperture radar interferometry reveals transient strain accumulation along the Blackwater-Little Lake fault system within the Eastern California shear zone. The surface strain map obtained by averaging eight years (1992-2000) of Earth Resource Satellite (ERS) radar data shows a 120-km-long, 20-km-wide zone of concentrated shear between the southern end of the 1872 Owens Valley earthquake surface break and the northern end of the 1992 Landers earthquake surface break. The observed shear zone is continuous through the Garlock fault, which does not show any evidence of left-lateral slip during the same time period. A dislocation model of the observed shear indicates right-lateral slip at 7 +/- 3 mm/yr on a vertical fault below similar to5 km depth, a rate that is two to three times greater than the geologic rates estimated on northwest-trending faults in the eastern Mojave area. This transient slip rate and the absence of resolvable slip on the Garlock fault may be the manifestation of an oscillatory strain pattern between interacting, conjugate fault systems. C1 Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Peltzer, G (reprint author), Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. NR 37 TC 133 Z9 135 U1 0 U2 7 PU GEOLOGICAL SOC AMERICA, INC PI BOULDER PA PO BOX 9140, BOULDER, CO 80301-9140 USA SN 0091-7613 J9 GEOLOGY JI Geology PD NOV PY 2001 VL 29 IS 11 BP 975 EP 978 DI 10.1130/0091-7613(2001)029<0975:TSAAFI>2.0.CO;2 PG 4 WC Geology SC Geology GA 494NY UT WOS:000172289800002 ER PT J AU Connerney, JEP Acuna, MH Wasilewski, PJ Kletetschka, G Ness, NF Reme, H Lin, RP Mitchell, DL AF Connerney, JEP Acuna, MH Wasilewski, PJ Kletetschka, G Ness, NF Reme, H Lin, RP Mitchell, DL TI The global magnetic field of Mars and implications for crustal evolution SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SURVEYOR MISSION; TOPOGRAPHY; ANOMALIES; HEMATITE; MAP AB The Mars Global Surveyor spacecraft obtained globally-distributed vector magnetic field measurements approximately 400 km above the surface of Mars. These have been compiled to produce the first complete global magnetic field maps of Mars. Crustal magnetization appears dichotomized, with intense magnetization mainly confined to the ancient, heavily cratered highlands in the south. The global distribution of sources is consistent with a reversing dynamo that halted early in Mars evolution. Intense crustal magnetization requires an increased oxidation state relative to mantle-derived rock, consistent with assimilation of an aqueous component at crustal depths. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. Ctr Etud Spatiale Rayonnements, F-31028 Toulouse, France. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RP Connerney, JEP (reprint author), NASA, Goddard Space Flight Ctr, Code 695, Greenbelt, MD 20771 USA. RI Kletetschka, Gunther/C-9996-2011; connerney, john/I-5127-2013 OI Kletetschka, Gunther/0000-0002-0645-9037; NR 21 TC 170 Z9 176 U1 2 U2 17 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 2001 VL 28 IS 21 BP 4015 EP 4018 DI 10.1029/2001GL013619 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 485TM UT WOS:000171780000001 ER PT J AU Juillet-Leclerc, A Schmidt, G AF Juillet-Leclerc, A Schmidt, G TI A calibration of the oxygen isotope paleothermometer of coral aragonite from Porites SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SEA-SURFACE TEMPERATURE; GALAPAGOS CORALS; RECORD; VARIABILITY; PACIFIC; CARBONATES; CLIMATE; OCEAN AB The oxygen isotopic composition (delta O-18(aragonite)) Of coral aragonite is dependent upon two parameters, temperature and water oxygen isotopic composition. This tracer allows temperature reconstruction in tropical zones. Different published delta O-18:temperature relationships show a slope derived from the regression delta O-18 against T(degreesC) which varies between -0.16 and -0.23 for Porites genus. This implies greater uncertainty for paleoclimatic reconstruction. The calibrations were generated differently. They were obtained from several colonies, collected in different locations or the formula was derived from the same coral head following seasonal variations of temperature. The relationships took into account of delta O-18(sw) fluctuation or delta O-18(Sw) were estimated from salinity or were not considered, We show by using isotopic data from Weber and Woodhead (1972) and assessing the delta O-18(Sw) value by two different methods that a thermodynamically significant formula is generated. C1 CEA, CNRS, Lab Sci Climat & Environm, F-91198 Gif Sur Yvette, France. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Juillet-Leclerc, A (reprint author), CEA, CNRS, Lab Sci Climat & Environm, F-91198 Gif Sur Yvette, France. RI Schmidt, Gavin/D-4427-2012 OI Schmidt, Gavin/0000-0002-2258-0486 NR 21 TC 32 Z9 36 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 2001 VL 28 IS 21 BP 4135 EP 4138 DI 10.1029/2000GL012538 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 485TM UT WOS:000171780000032 ER PT J AU Friend, AD AF Friend, AD TI Modelling canopy CO2 fluxes: are 'big-leaf' simplifications justified? SO GLOBAL ECOLOGY AND BIOGEOGRAPHY LA English DT Article DE big-leaf; canopy nitrogen profile; canopy photosynthesis; carbon flux; optimization; scaling ID NITROGEN ALLOCATION; GLOBAL RADIATION; DIRECT COMPONENT; PHOTOSYNTHESIS; LEAVES; TRANSPIRATION; LIGHT; ASSIMILATION; CONDUCTANCE; ACCLIMATION AB 1 The 'big-leaf' approach to calculating the carbon balance of plant canopies is evaluated for inclusion in the ETEMA model framework. This approach assumes that canopy carbon fluxes have the same relative responses to the environment as any single leaf, and that the scaling from leaf to canopy is therefore linear. 2 A series of model simulations was performed with two models of leaf photosynthesis, three distributions of canopy nitrogen, and two levels of canopy radiation detail. Leaf- and canopy-level responses to light and nitrogen, both as instantaneous rates and daily integrals, are presented. 3 Observed leaf nitrogen contents of unshaded leaves are over 40% lower than the bib leaf approach requires. Scaling from these leaves to the canopy using the big-leaf approach may underestimate canopy photosynthesis by similar to 20%. A leaf photosynthesis model that treats within-leaf light extinction displays characteristics that contradict the big-leaf theory. Observed distributions of canopy nitrogen are closer to those required to optimize this model than the homogeneous model used in the big-leaf approach. 4 It is theoretically consistent to use the big-leaf approach with the homogeneous photosynthesis model to estimate canopy carbon fluxes if canopy nitrogen and leaf area are known and if the distribution of nitrogen is assumed optimal. However, real nitrogen profiles are not optimal for this photosynthesis model, and caution is necessary in using the big-leaf approach to scale satellite estimates of leaf physiology to canopies. Accurate prediction of canopy carbon fluxes requires canopy nitrogen, leaf area, declining nitrogen with canopy depth, the heterogeneous model of leaf photosynthesis and the separation of sunlit and shaded leaves. The exact nitrogen profile is not critical, but realistic distributions can be predicted using a simple model of canopy nitrogen allocation. C1 Rutgers State Univ, Ctr Environm Predict, New Brunswick, NJ 08901 USA. RP Friend, AD (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 28 TC 52 Z9 57 U1 1 U2 14 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0960-7447 J9 GLOBAL ECOL BIOGEOGR JI Glob. Ecol. Biogeogr. PD NOV PY 2001 VL 10 IS 6 BP 603 EP 619 DI 10.1046/j.1466-822x.2001.00268.x PG 17 WC Ecology; Geography, Physical SC Environmental Sciences & Ecology; Physical Geography GA 496NV UT WOS:000172403600003 ER PT J AU Clifford, SM Parker, TJ AF Clifford, SM Parker, TJ TI The evolution of the Martian hydrosphere: Implications for the fate of a primordial ocean and the current state of the northern plains SO ICARUS LA English DT Article; Proceedings Paper CT 2nd International Conference on Mars Polar Science and Exploration CY AUG 21-25, 2000 CL REYKJAVIK, ICELAND SP Lunar & Planetary Inst, NASA, Univ Iceland Reykjavik, Geolog Survey Canada, Int Glaciol Soc DE Mars, surface; Mars, atmosphere; Mars, climate; ices; exobiology ID ORBITER LASER ALTIMETER; GROUND ICE INTERACTIONS; EARLY MARS; IMPACT BASINS; CHAOTIC OBLIQUITY; VALLES-MARINERIS; SEDIMENTARY DEPOSITS; GLOBAL DISTRIBUTION; CRUSTAL DICHOTOMY; CONTINENTAL-CRUST AB In this paper we consider the hydraulic and thermal conditions that gave rise to the elevated source regions of the Late Hesperian outflow channels and explore their implications for the evolution of the Martian hydrosphere. We find that if the outflow channel floodwaters were derived from a subpermafrost aquifer, then it implies that, throughout the planet's first billion years of evolution, as much as one third of its surface was covered by standing bodies of water and ice. Following the development of the global dichotomy, the bulk of this water would have existed as an ice-covered ocean in the northern plains. We demonstrate that the progressive crustal assimilation of this early surface reservoir of H(2)O (punctuated by possible episodes of less extensive flooding) was a natural consequence of the planet's subsequent climatic and geothermal evolution-potentially cycling the equivalent of a km-deep global ocean of water through the atmosphere and subsurface every similar to10(9) years. In response to the long-term decline in planetary heat flow, the progressive cold-trapping of H(2)O into the growing cryosphere is expected to have significantly depleted the original inventory of groundwater-a development that could well explain the apparent decline in outflow channel activity observed during the Amazonian. Although primarily a theoretical analysis, our findings appear remarkably consistent with the geomorphic and topographic evidence that Mars once possessed a primordial ocean and that a substantial relic of that body continues to survive as massive ice deposits within the northern plains. Confirmation of the presence of such deposits, combined with the potential detection of a global-scale groundwater system, would provide persuasive support for the validity of this analysis. (C) 2001 Elsevier Science. C1 Lunar & Planetary Inst, Houston, TX 77058 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Clifford, SM (reprint author), Lunar & Planetary Inst, 3600 Bay Area Blvd, Houston, TX 77058 USA. EM clifford@lpi.usra.edu NR 211 TC 302 Z9 306 U1 8 U2 41 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2001 VL 154 IS 1 BP 40 EP 79 DI 10.1006/icar.2001.6671 PG 40 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520TB UT WOS:000173796500004 ER PT J AU Cabrol, NA Wynn-Williams, DD Crawford, DA Grin, EA AF Cabrol, NA Wynn-Williams, DD Crawford, DA Grin, EA TI Recent aqueous environments in Martian impact craters: An astrobiological perspective SO ICARUS LA English DT Article; Proceedings Paper CT 2nd International Conference on Mars Polar Science and Exploration CY AUG 21-25, 2000 CL REYKJAVIK, ICELAND SP Lunar & Planetary Inst, NASA, Univ Iceland Reykjavik, Geolog Survey Canada, Int Glaciol Soc DE Mars; surface; exobiology; climate ID METABOLIC-ACTIVITY; DEEP SUBSURFACE; MARS; LIFE; EVOLUTION; ORIGIN; MICROORGANISMS; PERMAFROST; SURFACE; MODEL AB dThe discovery of gullies and debris aprons raises the question of the existence of aqueous environments on Mars in recent geological times and its astrobiological implications. Three cases of such environments are surveyed at MOC high resolution in the E-Gorgonum chaos and Newton and Hale craters. The regional setting of these craters suggests that the mechanisms of aquifer destabilization, flow discharge, and gully formation in these three cases result from local geological triggers that can include impact cratering, and tectonic processes, rather than climate or insolation factor. We take as a working hypothesis that microbial life appeared on Mars in ancient geological times, probably in a geothermal environment but potentially evolving via infrared detection systems to give photosynthetic communities under the selective pressure of energetic solar radiation. We hypothesize that some microbial communities could have survived underground in either dormant or active state, or that their biomolecules could be preserved either frozen or desiccated in the subsurface beneath the upper oxidized zone. We assess the known environmental constraints for life and what type of potential habitats are provided in these three craters by aquifer discharges using comparison with terrestrial analogues and their associated microbial communities. These environments include: (1) the release of water on a dry crater floor in E-Gorgonum and the possibility for microorganisms and preserved biomolecules to be flushed out and mixed in with the sediment exposed at the surface; (2) the evidence of a recent lacustrine episode in the Newton crater with analogy to Antarctic Dry Valley lakes; (3) the exposure on the floor of Hale crater of material from a regional subsurface that is likely to have retained traces of one of the oldest martian bodies of water recognized to date (Parker et al. 2000) in the Argyre basin. We show how the water in Argyre (similar to3.8 billion years ago (Gya) was likely to have been alterated by hydrothermal processes and how the subsequent formation of the 150-km Hale crater on the northern ring of Argyre generated hydrothermal pumping. This accounts for the anomalously high location of the springs on the crater crests today with respect to the rest of the regional subsurface distribution. Finally, we envision current impact cratering as a factor for destabilizing aquifers on Mars today, thus creating new environments. We analyze the implications of impacts for two geological types of rock units that could harbor traces of life. As a result, we compare the potential of astrobiological exploration of crater floors, rims, and ejecta on future missions to Mars. (C) 2001 Elsevier Science. C1 SETI Inst, Mountain View, CA 94043 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. British Antarctic Survey, Nat Environm Res Council, Cambridge CB3 0ET, England. RP Cabrol, NA (reprint author), SETI Inst, 2035 Landing Dr, Mountain View, CA 94043 USA. EM ncabrol@mail.arc.nasa.gov NR 100 TC 49 Z9 49 U1 0 U2 8 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2001 VL 154 IS 1 BP 98 EP 112 DI 10.1006/icar.2001.6661 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520TB UT WOS:000173796500006 ER PT J AU Ivanov, AB Muhleman, DO AF Ivanov, AB Muhleman, DO TI Cloud reflection observations: Results from the Mars orbiter laser altimeter SO ICARUS LA English DT Article; Proceedings Paper CT 2nd International Conference on Mars Polar Science and Exploration CY AUG 21-25, 2000 CL REYKJAVIK, ICELAND SP Lunar & Planetary Inst, NASA, Univ Iceland Reykjavik, Geolog Survey Canada, Int Glaciol Soc DE Mars, atmosphere; ices; ice caps; clouds; CO(2) condensation ID ATMOSPHERE; MODEL; ICE; CAP AB Formation of the perennial ice caps is one of the most important climatic processes on Mars. Up to 25% of the atmosphere is recycled each year through the ice caps. CO(2) ice may form on cold surfaces when temperatures are low enough (similar to146 K) or condense in the atmosphere and fall down on the surface as snow. Condensation of CO(2) is easily predicted by the models but has not been observed directly in any significant detail. However, formation of thick CO(2) clouds may have important implications for the martian climate. We describe observations of cloud echoes during the polar night by the Mars Orbiter Laser Altimeter. We argue that most of these clouds are mostly composed of CO(2) ice. We present observations of cloud heights, and their locations and properties over the course of 1.5 martian years. We were able to distinguish at least two distinctive types of clouds on the basis of their location and spatial structure. We compare cloud echo locations with the Mars Global Surveyor Thermal Emission Spectrometer (TES) brightness temperature data. The results show some correlation with the anomalously low brightness temperatures ("cold" spots) in TES data. We suggest that these zones are due to snow or frost freshly formed on the ground and only in some rare cases to CO(2) snowfall. (C) 2001 Elsevier Science. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RP Ivanov, AB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS168-514, Pasadena, CA 91109 USA. EM anton.ivanov@jpl.nasa.gov RI Ivanov, Anton/C-8944-2014 OI Ivanov, Anton/0000-0001-8376-8581 NR 23 TC 32 Z9 32 U1 2 U2 5 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2001 VL 154 IS 1 BP 190 EP 206 DI 10.1006/icar.2001.6686 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 520TB UT WOS:000173796500013 ER PT J AU Alena, R Gilbaugh, B Glass, B Braham, SP AF Alena, R Gilbaugh, B Glass, B Braham, SP TI Communication system architecture for planetary exploration SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB Future human missions to Mars will require effective communications supporting exploration activities and scientific field data collection. Constraints on cost, size, weight, and power consumption for all communications equipment make optimization of these systems very important. These information and communication systems connect people and systems together into coherent teams performing the difficult and hazardous tasks inherent in planetary exploration. The communication network supporting vehicle telemetry data, mission operations, and scientific collaboration must have excellent reliability and flexibility. We propose hybrid communication architectures consisting of space-based links, a surface-based deployable mid-range communications network and a cluster of short-range links to solve the problems of connectivity and bandwidth, while meeting the other constraints of weight and power. A network of orbiting satellites could cover much of the planet surface, but this space-based capability may not be optimal for cost or performance. Specifically, a minimal space-based capability can be augmented using mobile cellular repeaters deployable by robots and human EVA. This method results in an increase in the number of radio nodes, but the distances separating them is decreased. This results in a significant increase in bandwidth and decrease in radio power, and therefore, node size, complexity, and power consumption. This paper will discuss the results of field testing such hybrid radio systems for the support of scientific surveys. System analysis of design tradeoffs will yield insight into optimal solutions that will be compared to other approaches providing a method of effectively evaluating new candidate architectures. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Simon Fraser Univ, Harbour Ctr, TIME Ctr, PolyLAB, Vancouver, BC, Canada. RP Alena, R (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 8 TC 6 Z9 6 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD NOV PY 2001 VL 16 IS 11 BP 4 EP 11 DI 10.1109/62.965005 PG 8 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA 491MR UT WOS:000172112800003 ER PT J AU Johnson, M Firoozbakhsh, K Moniem, M Jamshidi, M AF Johnson, M Firoozbakhsh, K Moniem, M Jamshidi, M TI Determining flexor-tendon repair techniques via soft computing - A multi-objective fuzzy-logic method aids in making the best medical decision SO IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE LA English DT Article C1 Univ New Mexico, Dept Elect & Comp Engn, ACE Ctr, NASA, Albuquerque, NM 87131 USA. Univ New Mexico Hosp, Albuquerque, NM USA. RP Johnson, M (reprint author), Univ New Mexico, Dept Elect & Comp Engn, ACE Ctr, NASA, Albuquerque, NM 87131 USA. NR 8 TC 2 Z9 2 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0739-5175 J9 IEEE ENG MED BIOL JI IEEE Eng. Med. Biol. Mag. PD NOV-DEC PY 2001 VL 20 IS 6 BP 176 EP 183 DI 10.1109/51.982290 PG 8 WC Engineering, Biomedical; Medical Informatics SC Engineering; Medical Informatics GA 517VU UT WOS:000173631800024 PM 11838250 ER PT J AU Bergman, LA Yeh, C Morookian, J AF Bergman, LA Yeh, C Morookian, J TI Advances in multichannel multiGbytes/s bit-parallel WDM single fiber link SO IEEE TRANSACTIONS ON ADVANCED PACKAGING LA English DT Article DE computer networks; parallel interconnects; solitons; time aligned transmission; WDM ID DIVISION-MULTIPLEXED BEAMS; NONLINEAR FIBER; PULSE AB For ultra-high-speed single media parallel interconnects, an all optical single fiber WDM format of transmitting parallel bits rather than a fiber ribbon format-where parallel bits are sent through corresponding parallel fibers in a ribbon format, can be the media of choice. Here, we shall discuss the realization of a multi-kin x Gbs/s bit-parallel WDM (BP-WDM) single fiber link. The distance-speed product of this single fiber link is more than several orders of magnitude higher than that of a fiber ribbon link. The design of a 12 b-parallel channels WDM system operating at 1 Gb/s per channel rate through a single fiber will first be presented. Experimental results for a two channel system operating at that rate are given. Further improvement of distance-speed product for the BP-WDM link can be obtained with JPL's newly developed 20 Gbs/s per channel laser diode array transmitter. Also, new computer simulation results on how a large amplitude co-propagating pulse may induce pulse compression on all the co-propagating data pulses, thereby improving the shaping of these pulses for a WDM system, will be presented and discussed. The existence of WDM solitons is also shown. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bergman, LA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 12 Z9 14 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1521-3323 J9 IEEE T ADV PACKAGING JI IEEE Trans. Adv. Packag. PD NOV PY 2001 VL 24 IS 4 BP 456 EP 462 DI 10.1109/6040.982829 PG 7 WC Engineering, Manufacturing; Engineering, Electrical & Electronic; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 521MD UT WOS:000173843000007 ER PT J AU Simon, MK Alouini, MS AF Simon, MK Alouini, MS TI On the difference of two chi-square variates with application to outage probability computation SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Article; Proceedings Paper CT 38th Annual Allerton Conference on Communication, Control and Computing CY OCT 04-06, 2000 CL MONTICELLO, ILLINOIS DE cellular mobile radio systems; central and noncentral chi-square distributions; co-channel interference; generalized Marcum Q-function; maximal ratio combining; Nakagami fading; outage probability; Rician fading ID MOBILE RADIO SYSTEMS; MULTIPLE NAKAGAMI INTERFERERS; COCHANNEL INTERFERENCE; FADING CHANNELS; DIVERSITY RECEPTION; M-DPSK; ERROR; ENVIRONMENT; PARAMETERS; SIGNAL AB An expression for the cumulative distribution function evaluated at zero of the difference of two chi-square variates with different number of degrees of freedom is derived and applied to the outage probability computation of cellular mobile radio systems in fading channels. In particular, a generic result is developed for this probability which takes on several forms, the simplest of which, is a single integral with finite limits and an integrand composed of elementary (exponential and trigonometric) functions. The results are applicable to cellular systems that are subject to independent identically distributed (i.i.d.) interfering signals and that employ maximal-ratio combining reception over i.i.d. diversity paths. Various fading channel models are assumed for the desired signal and interferers. For each desired signal/interferer combination, the outage probability is expressed in closed form in terms of a set of parameters that characterize the particular scenario. A tabulation of these various scenarios and their associated parameters for channels of practical interest is included. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Minnesota, Dept Elect & Comp Engn, Minneapolis, MN 55455 USA. RP Simon, MK (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 39 TC 32 Z9 33 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD NOV PY 2001 VL 49 IS 11 BP 1946 EP 1954 DI 10.1109/26.966071 PG 9 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 494UG UT WOS:000172303800012 ER PT J AU Beard, RW Lawton, J Hadaegh, FY AF Beard, RW Lawton, J Hadaegh, FY TI A coordination architecture for spacecraft formation control SO IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY LA English DT Article DE control architecture; coordinated control; interferometry; spacecraft formation flying ID MOBILE ROBOTS; ATTITUDE-CONTROL; CONSTELLATION; ROTATION AB This paper addresses the problem of coordinating multiple spacecraft to fly in tightly controlled formations. The main contribution of the paper is to introduce a coordination architecture that subsumes leader-following, behavioral, and virtual-structure approaches to the multiagent coordination problem. The architecture is illustrated through a detailed application of the ideas to the problem of synthesizing a multiple spacecraft interferometer in deep space. C1 Brigham Young Univ, Dept Elect & Comp Engn, Provo, UT 84602 USA. Raytheon Syst Co, Tucson, AZ 85734 USA. CALTECH, Jet Prop Lab, Guidance & Control Sect, Pasadena, CA 91109 USA. RP Brigham Young Univ, Dept Elect & Comp Engn, Provo, UT 84602 USA. EM beard@ee.byu.edu; jonathan_r_lawton@west.raytheon.com; Fred.Y.Hadaegh@jpl.nasa.gov NR 46 TC 406 Z9 435 U1 7 U2 43 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1063-6536 EI 1558-0865 J9 IEEE T CONTR SYST T JI IEEE Trans. Control Syst. Technol. PD NOV PY 2001 VL 9 IS 6 BP 777 EP 790 DI 10.1109/87.960341 PG 14 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA 486PL UT WOS:000171826100001 ER PT J AU Rodwell, MJW Urteaga, M Mathew, T Scott, D Mensa, D Lee, Q Guthrie, J Betser, Y Martin, SC Smith, RP Jaganathan, S Krishnan, S Long, SI Pullela, R Agarwal, B Bhattacharya, U Samoska, L Dahlstrom, M AF Rodwell, MJW Urteaga, M Mathew, T Scott, D Mensa, D Lee, Q Guthrie, J Betser, Y Martin, SC Smith, RP Jaganathan, S Krishnan, S Long, SI Pullela, R Agarwal, B Bhattacharya, U Samoska, L Dahlstrom, M TI Submicron scaling of HBTs SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article DE heterojunction bipolar transistors; integrated circuits (ICS) ID HETEROJUNCTION BIPOLAR-TRANSISTORS; BASE-COLLECTOR CAPACITANCE; VELOCITY OVERSHOOT; CIRCUITS; GAAS; GHZ AB The variation of heterojunction bipolar transistor (HBT) bandwidth with scaling is reviewed. High bandwidths are obtained by thinning the base and collector layers, increasing emitter current density, decreasing emitter contact resistivity, and reducing the emitter and collector junction widths. In mesa HBTs, minimum dimensions required for the base contact impose a minimum width for the collector junction, frustrating device scaling. Narrow collector junctions can be obtained by using substrate transfer or collector-undercut processes or, if contact resistivity is greatly reduced, by reducing the width of the base ohmic contacts in a mesa structure. HBTs with submicron collector junctions exhibit extremely high f(max) and high gains in mm-wave ICs. Transferred-substrate HBTs have obtained 21 dB unilateral power gain at 100 GHz. If extrapolated at -20 dB/decade, the power gain cutoff frequency f(max) is 1.1 THz. f(max) will be less than 1 THz if unmodeled electron transport physics produce a > 20 dB/decade variation in power gain at frequencies above 110 GHz. Transferred-substrate HBTs have obtained 295 GHz f(tau). The substrate transfer process provides microstrip interconnects on a low-e(tau) polymer dielectric with a electroplated gold ground plane. Important wiring parasitics, including wiring capacitance, and ground via inductance are substantially reduced. Demonstrated ICs include lumped and distributed amplifiers with bandwidths to 85 GHz and per-stage gain-bandwidth products over 400 GHz, and master-slave latches operating at 75 GHz. C1 Univ Calif Santa Barbara, Dept Elect & Comp Engn, Santa Barbara, CA 93106 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Rodwell, MJW (reprint author), Univ Calif Santa Barbara, Dept Elect & Comp Engn, Santa Barbara, CA 93106 USA. NR 57 TC 111 Z9 115 U1 1 U2 14 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD NOV PY 2001 VL 48 IS 11 BP 2606 EP 2624 DI 10.1109/16.960387 PG 19 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 486PQ UT WOS:000171826500021 ER PT J AU Piepmeier, JR Gasiewski, AJ AF Piepmeier, JR Gasiewski, AJ TI Digital correlation microwave polarimetry: Analysis and demonstration SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT International Geoscience and Remote Sensing Symposium (IGARSS 00) CY JUL 24-28, 2000 CL HONOLULU, HAWAII SP IEEE Geosci & Remote Sensing Soc DE correlator; digital; polarimetry; radiometer; Stokes vector ID BRIGHTNESS TEMPERATURES; QUANTIZATION; RADIOMETERS AB The design, analysis, and demonstration of a digital-correlation microwave polarimeter for use in Earth remote sensing is presented. We begin with an analysis of a three-level digital correlator and develop the correlator transfer function and radiometric sensitivity. A fifth-order polynomial regression is derived for inverting the digital correlation coefficient into the analog statistic. In addition, the effects of quantizer threshold asymmetry and hysteresis are discussed. A two-look unpolarized calibration scheme is developed for identifying correlation offsets. The developed theory and calibration method are verified using a 10.7 GHz and a 37.0 GHz polarimeter. The polarimeters are based upon 1-GS/s three-level digital correlators and measure the first three Stokes parameters. Through experiment, the radiometric sensitivity is shown to approach the theoretical as derived earlier in the paper and the two-look unpolarized calibration method is successfully compared with results using a polarimetric scheme. Finally, sample data from an aircraft experiment demonstrates that the polarimeter is highly useful for ocean wind-vector measurement. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 21146 USA. NOAA, Environm Technol Lab, Boulder, CO 80305 USA. RP Piepmeier, JR (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 21146 USA. NR 32 TC 16 Z9 20 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 2001 VL 39 IS 11 BP 2392 EP 2410 DI 10.1109/36.964976 PG 19 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 494LV UT WOS:000172284900009 ER PT J AU Blackwell, WJ Barrett, JW Chen, FW Leslie, RV Rosenkranz, PW Schwartz, MJ Staelin, DH AF Blackwell, WJ Barrett, JW Chen, FW Leslie, RV Rosenkranz, PW Schwartz, MJ Staelin, DH TI NPOESS aircraft sounder testbed-microwave (NAST-M): Instrument description and initial flight results SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT International Geoscience and Remote Sensing Symposium (IGARSS 00) CY JUL 24-28, 2000 CL HONOLULU, HAWAII SP IEEE Geosci & Remote Sensing Soc DE aircraft instrumentation; hurricane images; microwave imaging; microwave radiometry; precipitation; temperature profile retrievals ID PRECIPITATION; TEMPERATURE; SATELLITE; CALIBRATION; GHZ AB The National Polar-Orbiting Operational Environmental Satellite System (NPOESS) aircraft sounder testbed (NAST) has recently been developed and deployed on the NASA ER-2 high-altitude aircraft. The testbed consists of two co-located cross-track scanning instruments: a Fourier transform interferometer spectrometer (NAST-1) [1] with spectral coverage of 3.7-15.5 mum and a passive microwave spectrometer (NAST-M) with 17 channels near the oxygen absorption lines at 50-57 GHz and 118.75 GHz. The testbed provides the first coregistered imagery from high-resolution microwave and infrared sounders and will provide new data that will help 1) validate meteorological satellite environmental data record (EDR) feasibility, 2) define future satellite instrument specifications, and 3) demonstrate operational issues in ground validation, data calibration, and retrievals of meteorological parameters. To help validate the performance and potential of NAST-M, imagery was collected from more than 20 overpasses of hurricanes Bonnie and Earl during the Convection and Moisture Experiment (CAMEX-3), Florida, Summer 1998. The warm core and convection morphology of Hurricane Bonnie (August, 1998) is clearly revealed both by aircraft-based microwave brightness temperature imagery and temperature retrievals within the eye. Radiance comparisons with the Advanced Microwave Sounding Unit (AMSU) on the NOAA-15 satellite and radiosonde observations yield root mean-squared (RMS) agreements of approximately 1 K or less. C1 MIT, Elect Res Lab, Cambridge, MA 02139 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Blackwell, WJ (reprint author), MIT, Elect Res Lab, Cambridge, MA 02139 USA. RI Schwartz, Michael/F-5172-2016 OI Schwartz, Michael/0000-0001-6169-5094 NR 22 TC 27 Z9 28 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 2001 VL 39 IS 11 BP 2444 EP 2453 DI 10.1109/36.964981 PG 10 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 494LV UT WOS:000172284900014 ER PT J AU Hammer, PD Johnson, LF Strawa, AW Dunagan, SE Higgins, RG Brass, JA Slye, RE Sullivan, DV Smith, WH Lobitz, BM Peterson, DL AF Hammer, PD Johnson, LF Strawa, AW Dunagan, SE Higgins, RG Brass, JA Slye, RE Sullivan, DV Smith, WH Lobitz, BM Peterson, DL TI Surface reflectance mapping using interferometric spectral imagery from a remotely piloted aircraft SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT International Geoscience and Remote Sensing Symposium (IGARSS 00) CY JUL 24-28, 2000 CL HONOLULU, HAWAII SP IEEE Geosci & Remote Sensing Soc DE spectral imaging; Fourier transform (FT) spectroscopy; hyperspectral sensors; interferometers; remotely piloted aircraft; airborne measurements; surface albedo; canopy reflectance ID ARRAY SCANNED INTERFEROMETER; IMAGING SPECTROMETRY AB During October 1997, a prototype sensor was flown on an experimental remotely piloted aircraft (RPA) over the island of Kauai as part of a terrestrial remote sensing technology feasibility study. Here we describe the deployment, testing, and evaluation of the compact lightweight sensor design based on two-beam interferometry for acquiring visible and near-infrared spectral images. The resulting images of agricultural fields and an air base facility are presented and evaluated. Surface albedo measurements obtained from a ground based spectrometer and an atmospheric profile measured from a radiosonde were used to establish ground-truth and to evaluate the spectral imager's performance. Quantitative intercomparisons between ground-based and airborne-based measurements were made using an atmospheric model based on MODTRAN together with algorithms to account for the sensors' differences in instrumental line shape and spectral sampling grids. The future potential of this alternative sensor technology is discussed in the light of current and predicted sensor performance. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Calif State Univ Seaside, Earth Syst & Policy Inst, Seaside, CA 93955 USA. Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA. RP Hammer, PD (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 17 TC 8 Z9 9 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 2001 VL 39 IS 11 BP 2499 EP 2506 DI 10.1109/36.964987 PG 8 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 494LV UT WOS:000172284900020 ER PT J AU Pissinou, N Radev, I Makki, K Campbell, WJ AF Pissinou, N Radev, I Makki, K Campbell, WJ TI Spatio-temporal composition of video objects: Representation and querying in video database systems SO IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING LA English DT Article DE spatio-temporal modeling; video annotation; content-based retrieval; multimedia modeling; video database systems AB A key characteristic of video data is the associated spatial and temporal semantics. It is important that a video model models the characteristics of objects and their relationships in time and space. Allen's 13 temporal relationships [2] are often used in formulating queries that contain the temporal relationships among video frames. For the spatial relationships, most of the approaches are based on projecting objects on a two or three-dimensional coordinate system. However, very few attempts have been made formally to represent the spatio-temporal relationships of objects contained in the video data and to formulate queries with spatio-temporal constraints. The purpose of our work is to design a model representation for the specification of the spatio-temporal relationships among objects in video sequences. The model describes the spatial relationships among objects for each frame in a given video scene and the temporal relationships (for this frame) of the temporal intervals measuring the duration of these spatial relationships. It also models the temporal composition of an object, which reflects the evolution of object's spatial relationships over the subsequent frames in the video scene and in the entire video sequence. Our model representation also provides an effective and expressive way for the complete and precise specification of distances among objects in digital video. This model is a basis for the annotation of raw video. C1 Univ SW Louisiana, Ctr Adv Comp Studies, Lafayette, LA 70504 USA. NASA, Goddard Space Flight Ctr, Appl Informat Sci Branch, Greenbelt, MD 20771 USA. RP Pissinou, N (reprint author), Univ SW Louisiana, Ctr Adv Comp Studies, Lafayette, LA 70504 USA. EM pissinou@casc.usl.edu; isr@casc.usl.edu; kia@louisiana.edu NR 15 TC 5 Z9 5 U1 0 U2 4 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1041-4347 EI 1558-2191 J9 IEEE T KNOWL DATA EN JI IEEE Trans. Knowl. Data Eng. PD NOV-DEC PY 2001 VL 13 IS 6 BP 1033 EP 1040 DI 10.1109/69.971195 PG 8 WC Computer Science, Artificial Intelligence; Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 499MH UT WOS:000172574600013 ER PT J AU Zhou, L Kambhamettu, C Goldgof, DB Palaniappan, K Hasler, AF AF Zhou, L Kambhamettu, C Goldgof, DB Palaniappan, K Hasler, AF TI Tracking nonrigid motion and structure from 2D satellite cloud images without correspondences SO IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE LA English DT Article DE nonrigid objects; structure estimation; image motion estimation; fluid models ID TROPICAL CYCLONE; WIND FIELDS; FLUID-FLOW; PREDICTION; SEQUENCE AB Tracking both structure and motion of nonrigid objects from monocular images is an important problem in vision. In this paper, a hierarchical method which integrates local analysis (that recovers small details) and global analysis (that appropriately limits possible nonrigid behaviors) is developed to recover dense depth values and nonrigid motion from a sequence of 2D satellite cloud images without any prior knowledge of point correspondences. This problem is challenging not only due to the absence of correspondence information but also due to the lack of depth cues in the 2D cloud images (scaled orthographic projection). In our method, the cloud images are segmented into several small regions and local analysis is performed for each region. A recursive algorithm is proposed to integrate local analysis with appropriate global fluid model constraints, based on which a structure and motion analysis system, SMAS, is developed. We believe that this is the first reported system in estimating dense structure and nonrigid motion under scaled orthographic views using fluid model constraints. Experiments on cloud image sequences captured by meteorological satellites (GOES-8 and GOES-9) have been performed using our system, along with their validation and analyses. Both structure and 3D motion correspondences are estimated to subpixel accuracy. Our results are very encouraging and have many potential applications in earth and space sciences, especially in cloud models for weather prediction. C1 Univ Delaware, Dept Comp & Informat Sci, VIMS Lab, Newark, DE 19716 USA. Univ S Florida, Dept Comp Sci & Engn, Tampa, FL 33620 USA. Univ Missouri, Dept Comp Engn & Comp Sci, Multimedia Commun & Visualizat Lab, Columbia, MO 65211 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Zhou, L (reprint author), Univ Delaware, Dept Comp & Informat Sci, VIMS Lab, Newark, DE 19716 USA. EM lzhou@cis.udel.edu; chandra@cis.udel.edu; goldgof@csee.usf.edu; palani@cecs.missouri.edu RI Palaniappan, Kannappan/A-3231-2008 NR 35 TC 28 Z9 30 U1 0 U2 8 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 0162-8828 EI 1939-3539 J9 IEEE T PATTERN ANAL JI IEEE Trans. Pattern Anal. Mach. Intell. PD NOV PY 2001 VL 23 IS 11 BP 1330 EP 1336 PG 7 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 491KV UT WOS:000172108300009 ER PT J AU Bell, AM Sethares, WA AF Bell, AM Sethares, WA TI Avoiding global congestion using decentralized adaptive agents SO IEEE TRANSACTIONS ON SIGNAL PROCESSING LA English DT Article DE coordination failure; El Farol; multiagent systems; network congestion ID ALGORITHMS; FILTER AB Everyone wants to go to a bar called El Farol if it is not crowded but would rather stay home if it is. Unfortunately, the only way to know whether or not the bar is crowded is to go. While such a scenario appears far removed from the typical communications literature, it provides a simple paradigm for analyzing public goods like the Internet, which may simultaneously suffer from congestion and coordination problems, e.g., multiple users trying to connect to the same server or to use the same resource simultaneously. This paper reviews previous solutions to the El Farol Santa Fe bar problem, which typically involve complex learning algorithms. A simple adaptive strategy similar to many signal processing algorithms such as LMS and its signed variants is proposed. The strategy is investigated via simulation, and the algorithm is analyzed in a few simple cases. Unlike most signal processing applications, the objective of the adaptation is not fast and accurate parameter estimation but rather the achievment of a degree of global coordination among users. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Wisconsin, Dept Elect & Comp Engn, Madison, WI 53706 USA. RP Bell, AM (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 20 TC 4 Z9 5 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1053-587X J9 IEEE T SIGNAL PROCES JI IEEE Trans. Signal Process. PD NOV PY 2001 VL 49 IS 11 BP 2873 EP 2879 DI 10.1109/78.960435 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA 485WD UT WOS:000171785700040 ER PT J AU Maluf, DA Tran, PB AF Maluf, DA Tran, PB TI Articulation management for intelligent integration of information SO IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS PART C-APPLICATIONS AND REVIEWS LA English DT Article DE articulation rules; domain algebra; heterogeneous systems; integration; intelligent information systems; semantic interoperation AB When combining data from distinct sources, there is a need to share meta-data and other knowledge about various source domains. Due to semantic inconsistencies and heterogeneity of representations, problems arise in combining multiple domains when the domains are merged. The knowledge that is irrelevant to the task of interoperation will be included, making the result unnecessarily complex. This heterogeneity problem can be eliminated by mediating the conflicts and managing the intersections of the domains. For interoperation and intelligent access to heterogeneous information, the focus is on the intersection of the knowledge, since intersection will define the required articulation rules. An algebra over domain has been proposed to use articulation rules to support disciplined manipulation of domain knowledge resources. The objective of a domain algebra is to provide the capability for interrogating many domain knowledge resources, which are largely semantically disjoint. The algebra supports formally the tasks of selecting, combining, extending, specializing, and modifying components from a diverse set of domains. This paper presents a domain algebra and demonstrates the use of articulation rules to link declarative interfaces for Internet and enterprise applications. In particular, it discusses the articulation implementation as part of a production system capable of operating over the domain described by the interface description language (IDL) of objects registered in multiple common object request broker architecture (CORBA) servers. C1 NASA, Ames Res Ctr, Div Computat Sci, Moffett Field, CA 94035 USA. QSS Grp Inc, Moffett Field, CA 94035 USA. RP NASA, Ames Res Ctr, Div Computat Sci, Moffett Field, CA 94035 USA. EM maluf@email.arc.nasa.gov; pbtran@mail.arc.nasa.gov NR 46 TC 4 Z9 4 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1094-6977 EI 1558-2442 J9 IEEE T SYST MAN CY C JI IEEE Trans. Syst. Man Cybern. Part C-Appl. Rev. PD NOV PY 2001 VL 31 IS 4 BP 485 EP 496 DI 10.1109/5326.983932 PG 12 WC Computer Science, Artificial Intelligence; Computer Science, Cybernetics; Computer Science, Interdisciplinary Applications SC Computer Science GA 520RY UT WOS:000173796200007 ER PT J AU Alouini, MS Simon, MK AF Alouini, MS Simon, MK TI Performance analysis of coherent equal gain combining over Nakagami-m fading channels SO IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY LA English DT Article; Proceedings Paper CT 49th IEEE Vehicular Technology Conference (VTC 99) CY MAY 16-JUN 20, 1999 CL HOUSTON, TEXAS SP IEEE DE diversity combining; equal gain combining; Nakagami-fading channels ID UNIFIED APPROACH; RAYLEIGH CHANNELS; MPSK SIGNALS; ERROR RATES; PROBABILITY; DIVERSITY AB We study the exact average output signal-to-noise ratio (SNR) and symbol error rate (SER) of M-ary phase-shift-keying (PSK) signals with coherent equal gain combining reception. The analysis assumes independent Nakagami-m fading paths, which are not necessarily identically distributed. On one hand, we use geometric summations to obtain closed-form expressions for the average output SNR over diversity paths with an exponentially decaying power delay profile. On the other hand, capitalizing on an alternative integral representation of the conditional SER along with Gauss-Hermite quadrature integration, we derive average SER expression in the form of a single finite-range integral and an integrand composed of tabulated functions. We also present a simpler but approximate approach for the closed-form evaluation of the SER of these signals over independent identically distributed Nakagami-m fading paths. C1 Univ Minnesota, Dept Elect & Elect Engn, Minneapolis, MN 55455 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Alouini, MS (reprint author), Univ Minnesota, Dept Elect & Elect Engn, Minneapolis, MN 55455 USA. NR 33 TC 47 Z9 49 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9545 J9 IEEE T VEH TECHNOL JI IEEE Trans. Veh. Technol. PD NOV PY 2001 VL 50 IS 6 BP 1449 EP 1463 DI 10.1109/25.966576 PG 15 WC Engineering, Electrical & Electronic; Telecommunications; Transportation Science & Technology SC Engineering; Telecommunications; Transportation GA 494TX UT WOS:000172302900012 ER PT J AU Nickerson, CA Goodwin, TJ Terlonge, J Ott, CM Buchanan, KL Uicker, WCD Emami, K LeBlanc, CL Ramamurthy, R Clarke, MS Vanderburg, CR Hammond, T Pierson, DL AF Nickerson, CA Goodwin, TJ Terlonge, J Ott, CM Buchanan, KL Uicker, WCD Emami, K LeBlanc, CL Ramamurthy, R Clarke, MS Vanderburg, CR Hammond, T Pierson, DL TI Three-dimensional tissue assemblies: Novel models for the study of Salmonella enterica serovar typhimurium pathogenesis SO INFECTION AND IMMUNITY LA English DT Article ID INTESTINAL EPITHELIAL-CELLS; FLUID SECRETION; BACTERIAL INVASION; MOLECULAR-BASIS; HOST-CELL; APOPTOSIS; INHIBITION; INDUCTION; VIRULENCE; PROTEIN AB The lack of readily available experimental systems has limited knowledge pertaining to the development of Salmonella-induced gastroenteritis and diarrheal disease in humans. We used a novel low-shear stress cell culture system developed at the National Aeronautics and Space Administration in conjunction with cultivation of three-dimensional (3-D) aggregates of human intestinal tissue to study the infectivity of Salmonella enterica serovar Typhimurium for human intestinal epithelium. Immunohistochemical characterization and microscopic analysis of 3-D aggregates of the human intestinal epithelial cell line Int-407 revealed that the 3-D cells more accurately modeled human in vivo differentiated tissues than did conventional monolayer cultures of the same cells. Results from infectivity studies showed that Salmonella established infection of the 3-D cells in a much different manner than that observed for monolayers. Following the same time course of infection with Salmonella, 3-D Int-407 cells displayed minimal loss of structural integrity compared to that of Int-407 monolayers. Furthermore, Salmonella exhibited significantly lower abilities to adhere to, invade, and induce apoptosis of 3-D Int-407 cells than it did for infected Int-407 monolayers. Analysis of cytokine expression profiles of 3-D Int-407 cells and monolayers following infection with Salmonella revealed significant differences in expression of interleukin 1 alpha- (IL-1 alpha), IL-1 beta, IL-6, IL-1Ra, and tumor necrosis factor alpha mRNAs between the two cultures. In addition, uninfected 3-D Int-407 cells constitutively expressed higher levels of transforming growth factor beta1 mRNA and prostaglandin E-2 than did uninfected Int-407 monolayers. By more accurately modeling many aspects of human in vivo tissues, the 3-D intestinal cell model generated in this study offers a novel approach for studying microbial infectivity from the perspective of the host-pathogen interaction. C1 Tulane Univ, Sch Med, Dept Microbiol & Immunol, Program Mol Pathogenesis & Immun, New Orleans, LA 70112 USA. NASA, Life Sci Res Labs, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, EASI Wyle Labs, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Space Res Assoc, Div Space Life Sci, Houston, TX 77058 USA. Massachusetts Gen Hosp, Boston, MA 02114 USA. Tulane Univ, Med Ctr, Nephrol Sect, New Orleans, LA 70112 USA. RP Nickerson, CA (reprint author), Tulane Univ, Sch Med, Dept Microbiol & Immunol, Program Mol Pathogenesis & Immun, SL38,1430 Tulane Ave, New Orleans, LA 70112 USA. NR 47 TC 83 Z9 85 U1 2 U2 12 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1752 N ST NW, WASHINGTON, DC 20036-2904 USA SN 0019-9567 J9 INFECT IMMUN JI Infect. Immun. PD NOV PY 2001 VL 69 IS 11 BP 7106 EP 7120 DI 10.1128/IAI.69.11.7106-7120.2001 PG 15 WC Immunology; Infectious Diseases SC Immunology; Infectious Diseases GA 485DX UT WOS:000171739200065 PM 11598087 ER PT J AU Yoon, KE Isheim, D Noebe, RD Seidman, DN AF Yoon, KE Isheim, D Noebe, RD Seidman, DN TI Nanoscale studies of the chemistry of a Rene N6 superalloy SO INTERFACE SCIENCE LA English DT Article; Proceedings Paper CT International Conference on Intergranula and Interphase Boundaries (iib2001) CY 2001 CL HAIFA, ISRAEL DE nickel-based superalloy; three-dimensional atom-probe microscopy; rhenium; Gibbsian interfacial excesses ID 3-DIMENSIONAL ATOM-PROBE; FIELD-ION MICROSCOPY; SCALE; INTERFACES; RHENIUM AB Atom-probe field-ion microscopy (APFIM) is used to study partitioning of the alloying elements between the gamma (FCC) and gamma' (L1(2)) phases and their segregation behavior at gamma/gamma' interfaces of a Rene N6 nickel-based superalloy. The atomic-scale resolution and real space reconstruction capability for elemental chemical mapping makes three-dimensional atom-probe microscopy especially suitable for subnanoscale investigations of complex multicomponent superalloys. Concentration profiles of this alloy, obtained from an atom probe analysis, reveal the partitioning behavior of the alloying elements in Rene N6. As anticipated, the matrix strengtheners, such as Mo and W, are partitioned to the gamma (FCC) matrix, while Re segregates at the gamma/gamma' interfaces; the Gibbsian interfacial excess of Re is determined by both one-dimensional (2.32 atoms nm(-)2) and three-dimensional atom-probe microscopies (3.92 atoms nm(-)2) and the values obtained are in reasonable agreement. C1 Northwestern Univ, Dept Mat Sci & Engn, Evanston, IL 60208 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RI Seidman, David/B-6697-2009; Isheim, Dieter/B-7524-2009 NR 16 TC 35 Z9 35 U1 1 U2 8 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0927-7056 J9 INTERFACE SCI JI Interface Sci. PD NOV PY 2001 VL 9 IS 3-4 BP 249 EP 255 DI 10.1023/A:1015158728191 PG 7 WC Materials Science, Multidisciplinary; Physics, Condensed Matter SC Materials Science; Physics GA 542TU UT WOS:000175061000016 ER PT J AU Zhang, NL AF Zhang, NL TI Innovative heat pipe systems using a new working fluid SO INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER LA English DT Article ID TEMPERATURE; CONVECTION; MENISCUS; SURFACE; MINIMUM; DROPS AB The operating temperature and the heat load of capillary-pumping heat-pipe systems are much lower than maximum attainable limit, and the systems suffer operational instability problems because the working fluid has a negative surface-tension gradient with temperature that is unfavorable for the spreading or re-wetting on a heated surface. The present paper suggests an innovation of heat-pipe system by using new working fluids, which have a positive gradient of surface tension with temperature, to improve the performance of capillary-pumping heat-pipe systems and their operative stability. Published by Elsevier Science Ltd. C1 NASA, Glenn Res Ctr, Micrograv Sci Div, Cleveland, OH 44135 USA. RP Zhang, NL (reprint author), NASA, Glenn Res Ctr, Micrograv Sci Div, Cleveland, OH 44135 USA. NR 20 TC 17 Z9 17 U1 3 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0735-1933 J9 INT COMMUN HEAT MASS JI Int. Commun. Heat Mass Transf. PD NOV PY 2001 VL 28 IS 8 BP 1025 EP 1033 DI 10.1016/S0735-1933(01)00306-2 PG 9 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA 503BG UT WOS:000172776800002 ER PT J AU Tucker, CJ Slayback, DA Pinzon, JE Los, SO Myneni, RB Taylor, MG AF Tucker, CJ Slayback, DA Pinzon, JE Los, SO Myneni, RB Taylor, MG TI Higher northern latitude normalized difference vegetation index and growing season trends from 1982 to 1999 SO INTERNATIONAL JOURNAL OF BIOMETEOROLOGY LA English DT Article DE growing season; phenology; photosynthesis; climate change; time series; northern latitudes ID AIR-TEMPERATURE; ATMOSPHERIC CO2; REFLECTANCE; RISE AB Normalized difference vegetation index data from the polar-orbiting National Oceanic and Atmospheric Administration meteorological satellites from 1982 to 1999 show significant variations in photosynthetic activity and growing season length at latitudes above 35 degreesN. Two distinct periods of increasing plant growth are apparent: 1982-1991 and 1992-1999. separated by a reduction from 1991 to 1992 associated with global cooling resulting from the volcanic eruption of Mt. Pinatubo in June 1991. The average May to September normalized difference vegetation index from 45 degreesN to 75 degreesN increased by 9% from 1982 to 1991, decreased by 5% from 1991 to 1992. and increased by 8% from 1992 to 1999. Variations in the normalized difference vegetation index were associated with variations in the start of the growing, season of -5.6, +3.9, and -1.7 days respectively. for the three time periods. Our results support surface temperature increases within the same period at higher northern latitudes where temperature limits plant growth. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. Boston Univ, Dept Geog, Boston, MA 02215 USA. RP Tucker, CJ (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Code 923, Greenbelt, MD 20771 USA. RI Slayback, Daniel/E-7465-2011; Los, Sietse/G-8985-2012; Myneni, Ranga/F-5129-2012; OI Los, Sietse/0000-0002-1325-3555 NR 28 TC 374 Z9 449 U1 8 U2 87 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0020-7128 J9 INT J BIOMETEOROL JI Int. J. Biometeorol. PD NOV PY 2001 VL 45 IS 4 BP 184 EP 190 DI 10.1007/s00484-001-0109-8 PG 7 WC Biophysics; Environmental Sciences; Meteorology & Atmospheric Sciences; Physiology SC Biophysics; Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences; Physiology GA 499JQ UT WOS:000172568400004 PM 11769318 ER PT J AU Kradinov, V Barut, A Madenci, E Ambur, DR AF Kradinov, V Barut, A Madenci, E Ambur, DR TI Bolted double-lap composite joints under mechanical and thermal loading SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article DE bolt; double lap; joint; composite; mechanical; thermal AB This study concerns the determination of the contact stresses and contact region around bolt holes and the bolt load distribution in single- and double-lap joints of composite laminates with arbitrarily located bolts under general mechanical loading conditions and uniform temperature change. The unknown contact stress distribution and contact region between the bolt and laminates and the interaction among the bolts require the bolt load distribution, as well as the contact stresses, to be as part of the solution. The present method is based on the complex potential theory and the variational formulation in order to account for bolt stiffness, bolt-hole clearance, and finite geometry of the composite laminates. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Arizona, Dept Aerosp & Mech Engn, Tucson, AZ 85721 USA. NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23665 USA. RP Madenci, E (reprint author), Univ Arizona, Dept Aerosp & Mech Engn, POB 210119, Tucson, AZ 85721 USA. NR 9 TC 17 Z9 17 U1 1 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7683 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD NOV PY 2001 VL 38 IS 44-45 BP 7801 EP 7837 DI 10.1016/S0020-7683(01)00128-7 PG 37 WC Mechanics SC Mechanics GA 485FP UT WOS:000171743100005 ER PT J AU Bednarcyk, BA AF Bednarcyk, BA TI Discussion of "Woven fabric composite material model with material non-linearity for non-linear finite element simulation" by Tabiei and Jiang - [Int. J. Solids Struct. 36 (1999) 2757-2771] SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Editorial Material ID METAL-MATRIX COMPOSITES; MICROMECHANICAL ANALYSIS; CARBON/COPPER COMPOSITE; CONSTITUTIVE-EQUATIONS; MULTIPHASE COMPOSITES; INELASTIC RESPONSE; DAMAGE; CELLS AB Tabiei and Jiang (1999) present an approach in which, through homogenization, a model for a woven composite material is developed. The model is suitable for implementation in commercial finite element (FE) packages (to represent a material point). This then enables analysis of structures composed of the woven composite while providing the local stresses and strains in the woven composite yams at the FE material points. Hence, the objective of the paper, in my opinion, is extremely worthwhile. This type of multi-scale approach to structural analysis shows potential for improving designs, as well as streamlining the design procedure, for structures composed of advanced materials (such as woven composites). In developing the model for the woven composite, Tabiei and Jiang (1999) identify a repeating unit cell (in the plane of the weave) and divide the unit cell into subcells. Each subcell is then homogenized through the weave's thickness via iso-stress and iso-strain conditions. The composite is thus represented, at this point, by a repeating unit cell consisting of an array of two-dimensional subcells, each with effective (homogenized) properties (see Fig. 1). The next step in the model development involves homogenization of the two-dimensional subcells to obtain the effective constitutive equations for the repeating unit cell (Tabiei and Jiang, 1999, Section 2.2, p. 2764). Here, the authors state, "... it is assumed that the average in-plane strains and stresses among subcells have the following relationships..." (Tabiei and Jiang, 1999, p. 2764), and 16 equations are presented, which relate the local (subcell) and global (homogenized) stresses and strains in the repeating unit cell. Although no reference is given, it is my opinion that these equations are, in actuality, the generalized method of cells (GMC) equations developed by Paley and Aboudi (1992). Figs. I and 2 compare the geometry employed by Tabici and Jiang with that of GMC, while Table I presents the correspondence between the equations presented by Tabiei and Jiang (1999) and the GMC equations presented by Paley and Aboudi (1992). C1 NASA, Glenn Res Ctr, Ohio Aerosp Inst, Cleveland, OH 44135 USA. RP Bednarcyk, BA (reprint author), NASA, Glenn Res Ctr, Ohio Aerosp Inst, MS 49-7,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 25 TC 5 Z9 6 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7683 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD NOV PY 2001 VL 38 IS 46-47 BP 8585 EP 8588 DI 10.1016/S0020-7683(01)00067-1 PG 4 WC Mechanics SC Mechanics GA 495YH UT WOS:000172367600022 ER PT J AU Rossow, VJ AF Rossow, VJ TI Aircraft spacings that produce vortex-free region below flight formations SO JOURNAL OF AIRCRAFT LA English DT Article AB A preliminary theoretical study is presented of a concept whereby the vortex wakes shed by a formation of aircraft can be redirected to produce a large region below the formation that is free of vortices. The redirection of the vortices is accomplished by first spacing the aircraft so that vortex pairs are formed between the wingtips of adjacent aircraft. If the aircraft spacings are within certain limits that are presented in the analysis, the self-induced velocity field of the vortex pairs causes all of the inboard vortices to move upward rather that downward. One application for such a process is the deployment of paratroopers from aircraft so that, while descending to the ground, no parachute will come near the lift-generated vortices shed by the deploying, or other nearby aircraft. The purpose of the study is to find out whether spacings between aircraft in a formation can be established so that the lift-generated vortices being trailed move upward rather than downward. Because the vortices shed by a single aircraft must always descend, attention was focused on multiple aircraft formations. It was found that the method is feasible and makes it possible to arrange close formations of aircraft so that all of the inboard trailing vortices move upward rather than downward. The two outboard vortices then travel downward at a greatly reduced velocity that depends on the number of aircraft in the formation. All of the inboard region below the formation is then free of vortices. The stability of spacings between aircraft in successful formations and the instrumentation required for implementation of the concept introduced are not treated. C1 NASA, Ames Res Ctr, Aerosp Operat Modeling Off, Moffett Field, CA 94035 USA. RP Rossow, VJ (reprint author), NASA, Ames Res Ctr, Aerosp Operat Modeling Off, Mail Stop 210-10, Moffett Field, CA 94035 USA. NR 21 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2001 VL 38 IS 6 BP 977 EP 987 DI 10.2514/2.2871 PG 11 WC Engineering, Aerospace SC Engineering GA 502KR UT WOS:000172743200001 ER PT J AU Cliff, SE Reuther, JJ Saunders, DA Hicks, RM AF Cliff, SE Reuther, JJ Saunders, DA Hicks, RM TI Single-point and multipoint aerodynamic shape optimization of high-speed civil transport SO JOURNAL OF AIRCRAFT LA English DT Article AB Single-point and multipoint aerodynamic shape optimization methods were developed and demonstrated for the design of an advanced supersonic transport subject to many geometric constraints. The starting point configuration baseline was developed in support of the NASA High-Speed Research program using linear-theory-based methods and multidisciplinary system analyses. The single-point design method simulated the presence of nacelles and diverters at supersonic cruise by superimposing nacelles-on/nacelles-off pressure differences, from complete configuration analyses, onto single-block-grid wing/body calculations. The multipoint design method used a multiblock grid to treat the complete configuration, including nacelles/diverters, canard, empennage, and wing flaps/slats. Two forms of multipoint optimization were performed at Mach 2.4, 1.1, and 0.9: sequential (design at cruise followed by flap and canard/tail incidence angle optimization at the two transonic conditions) and multipoint (simultaneous design at the three flight conditions via a composite objective function). Euler-based optimization using a combination of the two methods achieved significant performance gains derived from the nonlinear effects. The single-point approach produced much of the improvement, lowering the appropriately weighted thrust coefficient by 4.28 counts after trimming the full configuration at the three design points. (A seven count drag reduction was achieved at cruise for the untrimmed vehicle.) The sequential and multipoint methods achieved 6.03 and 7.55 counts of composite thrust reduction, respectively. C1 NASA, Ames Res Ctr, Syst Anal Branch, Aeronaut Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Reacting Flow Environm Branch, Aeronaut Div, Moffett Field, CA 94035 USA. RP Cliff, SE (reprint author), NASA, Ames Res Ctr, Syst Anal Branch, Aeronaut Div, MS 258-1, Moffett Field, CA 94035 USA. NR 26 TC 22 Z9 25 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2001 VL 38 IS 6 BP 997 EP 1005 DI 10.2514/2.2886 PG 9 WC Engineering, Aerospace SC Engineering GA 502KR UT WOS:000172743200003 ER PT J AU Samareh, JA AF Samareh, JA TI Novel multidisciplinary shape parameterization approach SO JOURNAL OF AIRCRAFT LA English DT Article ID B-SPLINES; OPTIMIZATION; GEOMETRY; DESIGN AB A multidisciplinary shape parameterization approach is presented. The approach consists of two basic concepts: 1) parameterizing the shape perturbations rather than the geometry itself and 2) performing the shape deformation by means of the soft object animation algorithms used in computer graphics. Because the formulation presented is independent of grid topology, we can treat computational fluid dynamics and finite element grids in the same manner. The proposed approach is simple, compact, and efficient. Also, the analytical sensitivity derivatives are easily computed for use in a gradient-based optimization. This algorithm is suitable for low-fidelity, for example, linear aerodynamics and equivalent laminated plate structures, and high-fidelity, for example, nonlinear computational fluid dynamics and detailed finite element modeling, analysis tools. The implementation details of parameterizing for planform, twist, dihedral, thickness, camber, and free-form surface are given. Results are presented for a multidisciplinary application consisting of nonlinear computational fluid dynamics, detailed computational structural mechanics, and a simple performance module. C1 NASA, Langley Res Ctr, Multidisciplinary Optimizat Branch, Hampton, VA 23665 USA. RP Samareh, JA (reprint author), NASA, Langley Res Ctr, Multidisciplinary Optimizat Branch, Mail Stop 159, Hampton, VA 23665 USA. NR 29 TC 15 Z9 15 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2001 VL 38 IS 6 BP 1015 EP 1024 DI 10.2514/2.2888 PG 10 WC Engineering, Aerospace SC Engineering GA 502KR UT WOS:000172743200005 ER PT J AU Rogers, SE Roth, K Cao, HV Nash, SM Baker, MD AF Rogers, SE Roth, K Cao, HV Nash, SM Baker, MD TI Computation of viscous flow for a Boeing 777 aircraft in landing configuration SO JOURNAL OF AIRCRAFT LA English DT Article AB A series of Navier-Stokes simulations of a complete Boeing 777-200 aircraft configured for landing is obtained using a structured overset grid process and the OVERFLOW computational fluid dynamics code. At approach conditions, the computed forces for the 777 computation are within 1.5% of experimental data for lift and within 4% for drag. The computed lift is lower than the experiment at maximum-lift conditions, but shows closer agreement at poststall conditions. The effect of sealing a spanwise gap between leading-edge elements and adding a chine onto the nacelle is computed at a high angle of attack. These additions make a significant difference in the flow over the wing near these elements. Detailed comparisons between computed and experimental surface pressures are shown. Good agreement is demonstrated at lower angles of attack, including a prediction of separated flow on the outboard flap. C1 NASA, Ames Res Ctr, Adv Supercomp Div, Moffett Field, CA 94035 USA. Boeing Co, Commercial Airplane Grp, Seattle, WA 98124 USA. Boeing Co, Subson Aerodynam Technol, Long Beach, CA 90807 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Rogers, SE (reprint author), NASA, Ames Res Ctr, Adv Supercomp Div, Moffett Field, CA 94035 USA. NR 13 TC 9 Z9 11 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2001 VL 38 IS 6 BP 1060 EP 1068 DI 10.2514/2.2873 PG 9 WC Engineering, Aerospace SC Engineering GA 502KR UT WOS:000172743200011 ER PT J AU Alexandrov, NA Lewis, RM Gumbert, CR Green, LL Newman, PA AF Alexandrov, NA Lewis, RM Gumbert, CR Green, LL Newman, PA TI Approximation and model management in aerodynamic optimization with variable-fidelity models SO JOURNAL OF AIRCRAFT LA English DT Article ID STRUCTURAL SYNTHESIS AB This work discusses an approach, first-order approximation and model management optimization (ANIMO), for solving design optimization problems that involve computationally expensive simulations. AMMO maximizes the use of lower-fidelity, cheaper models in iterative procedures with occasional, but systematic, recourse to higher-fidelity, more expensive models for monitoring the progress of design optimization. A distinctive feature of the approach is that it is globally convergent to a solution of the original, high-fidelity problem. Variants of ANIMO based on three nonlinear programming algorithms are demonstrated on a three-dimensional aerodynamic wing optimization problem and a two-dimensional airfoil optimization problem. Euler analysis on meshes of varying degrees of refinement provides a suite of variable-fidelity models. Preliminary results indicate threefold savings in terms of high-fidelity analyses for the three-dimensional problem and twofold savings for the two-dimensional problem. C1 NASA, Langley Res Ctr, Multidisciplinary Optimizat Branch, Hampton, VA 23665 USA. Coll William & Mary, Dept Math, Williamsburg, VA 23187 USA. NASA, Langley Res Ctr, Multidisciplinary Optimizat Branch, Hampton, VA 23681 USA. RP Gumbert, CR (reprint author), NASA, Langley Res Ctr, Multidisciplinary Optimizat Branch, M-S 159, Hampton, VA 23665 USA. EM buckaroo@math.wm.edu NR 24 TC 73 Z9 75 U1 2 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2001 VL 38 IS 6 BP 1093 EP 1101 DI 10.2514/2.2877 PG 9 WC Engineering, Aerospace SC Engineering GA 502KR UT WOS:000172743200015 ER PT J AU Woodward, RP Elliott, DM Hughes, CE Berton, JJ AF Woodward, RP Elliott, DM Hughes, CE Berton, JJ TI Benefits of swept-and-leaned stators for fan noise reduction SO JOURNAL OF AIRCRAFT LA English DT Article AB An advanced high bypass ratio fan model was tested in the NASA John H. Glenn Research Center 9 X 15 Foot Low-Speed Wind Tunnel. The primary focus of this test was to quantify the acoustic benefits and aerodynamic performance of sweep and lean in stator vane design. Three stator sets were used for this test series. A conventional radial stator set was tested at two rotor-stator axial spacings. Additional stator sets incorporating sweep only and sweep and lean were also tested. The hub axial location for the swept-and-leaned and swept-only stators was at the same axial location as the radial stator at the smaller rotor-stator spacing (upstream stator location), while the tip of these modified stators was at the same axial location as the radial stator set at the downstream rotor-stator spacing. The acoustic data show that swept and leaned stators give significant reductions in both rotor-stator interaction noise and broadband noise beyond what could be achieved through increased axial spacing of the conventional, radial stator. Application of these test results to a representative two-engine aircraft and flight path suggest that about a 3 effective perceived noise (EPN) dB fan noise reduction could be achieved through incorporation of these modified stators. This reduction would represent a significant portion of the 6-EPNdB aircraft noise reduction goal relative to that of 1992 technology levels of the current NASA Advanced Subsonic Technology initiative. C1 NASA, John H Glenn Res Ctr Lewis Field, Prop Syst Anal Off, Cleveland, OH 44135 USA. RP Woodward, RP (reprint author), NASA, John H Glenn Res Ctr Lewis Field, Prop Syst Anal Off, MS 54-3, Cleveland, OH 44135 USA. NR 11 TC 20 Z9 23 U1 3 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2001 VL 38 IS 6 BP 1130 EP 1138 DI 10.2514/2.2883 PG 9 WC Engineering, Aerospace SC Engineering GA 502KR UT WOS:000172743200020 ER PT J AU Burner, AW Liu, TS Garg, S Ghee, TA Taylor, NJ AF Burner, AW Liu, TS Garg, S Ghee, TA Taylor, NJ TI Aeroelastic deformation measurements of flap, gap, and overhang on a semispan model SO JOURNAL OF AIRCRAFT LA English DT Article AB Single-camera, single-view videogrammetry has been used for the first time to determine static aeroelastic deformation of a slotted flap configuration on a semispan model at the National Transonic Facility (NTF). Deformation was determined by comparing wind-off to wind-on spatial data from targets placed on the main element, shroud, and flap of the model. Digitized video images from a camera were recorded and processed to determine automatically target image plane locations that were then corrected for sensor, lens, and frame grabber spatial errors. The videogrammetric technique used for the measurements presented here has been established at NASA facilities as the technique of choice when high-volume static aeroelastic data with minimum impact on data taking are required. However, the primary measurement at the NTF with this technique in the past has been the measurement of the static aeroelastic wing twist of the main wing element on full span models rather than for the measurement of component deformation. Considerations for using the videogrammetric technique for semispan component deformation measurements as well as representative results are presented. C1 NASA, Langley Res Ctr, Instrumentat Syst Dev Branch, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Model Syst Branch, Hampton, VA 23681 USA. High Technol Corp, Hampton, VA 23666 USA. USN, Air Syst Command, Patuxent River, MD 20670 USA. Dev Evaluat & Res Agcy, Aerostruct Dept, Farnborough GU14 0LX, Hants, England. RP Ghee, TA (reprint author), NASA, Langley Res Ctr, Instrumentat Syst Dev Branch, MS 236, Hampton, VA 23681 USA. NR 9 TC 2 Z9 2 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2001 VL 38 IS 6 BP 1147 EP 1154 DI 10.2514/2.2885 PG 8 WC Engineering, Aerospace SC Engineering GA 502KR UT WOS:000172743200022 ER PT J AU Mayr, HG Mengel, JG Chan, KL Porter, HS AF Mayr, HG Mengel, JG Chan, KL Porter, HS TI Mesosphere dynamics with gravity wave forcing: Part I. Diurnal and semi-diurnal tides SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE tides; gravity waves; planetary waves ID DOPPLER-SPREAD PARAMETERIZATION; MIDDLE ATMOSPHERE; LOWER THERMOSPHERE; SEMIDIURNAL TIDE; MOMENTUM DEPOSITION; SEASONAL-VARIATIONS; PROPAGATING TIDE; MEAN WINDS; SOLAR; MODEL AB We present results from a non-linear, 3D, time dependent numerical spectral model, which extends from the ground up to the thermosphere and incorporates Hines' Doppler spread parameterization for small-scale gravity waves (GWs). Our focal point is the mesosphere, which is dominated by wave interactions. We discuss diurnal and semi-diurnal tides in the present paper (Part I) and planetary waves (PWs) in a companion paper (Part II). To study the seasonal variations of tides, in particular with regard to GW forcing, numerical experiments are performed that lead to the following conclusions: (1) The large semi-annual variations in the diurnal tide (DT), with peak amplitudes observed around equinox, are produced to a significant extent by GW interactions that involve, in part, PWs. (2) The DT, like PWs, is amplified by GW momentum deposition, which reduces also the vertical wavelength. (3) Variations in eddy viscosity associated with GW interactions may also influence the DT. (4) The semidiurnal tide (SDT), and its phase in particular, is strongly influenced by the zonal mean circulation. (5) Without the DT present, the SDT is amplified by GWs; but the DT filters out GWs such that the wave interaction significantly reduces the amplitude of the SDT during equinox, effectively producing a strong non-linear interaction between the DT and the SDT. (6) PWs generated internally by the baroclinic instability and GW forcing produce large amplitude modulations of the DT and SDT. (C) 2001 Published by Elsevier Science Ltd. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. Hong Kong Univ Sci & Technol, Hong Kong, Hong Kong, Peoples R China. Furman Univ, Greenville, SC 29613 USA. RP Mayr, HG (reprint author), NASA, Goddard Space Flight Ctr, MC 910-4, Greenbelt, MD 20771 USA. OI Chan, Kwing/0000-0002-6428-1812 NR 45 TC 22 Z9 22 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD NOV PY 2001 VL 63 IS 17 BP 1851 EP 1864 DI 10.1016/S1364-6826(01)00056-6 PG 14 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 491KD UT WOS:000172106800008 ER PT J AU Mayr, HG Mengel, JG Chan, KL Porter, HS AF Mayr, HG Mengel, JG Chan, KL Porter, HS TI Mesosphere dynamics with gravity wave forcing: Part II. Planetary waves SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE planetary waves; gravity waves ID RESOLUTION DOPPLER IMAGER; QUASI 2-DAY WAVE; THERMOSPHERE-IONOSPHERE SYSTEM; QUASI-2-DAY WAVE; RADAR OBSERVATIONS; MIDDLE ATMOSPHERE; SPREAD PARAMETERIZATION; BAROCLINIC INSTABILITY; MOMENTUM DEPOSITION; SEASONAL-VARIATIONS AB We present results from a non-linear, 3D, time dependent numerical spectral model (NSM), which extends from the ground up to the thermosphere and incorporates Hines' Doppler spread parameterization for small-scale gravity waves (GWs). Our focus is the mesosphere where wave interactions play a prominent role. We discuss planetary waves (PWs) in the present paper (Part II) and diurnal and semi-diurnal tides in the companion paper (Part I). Without external, time-dependent energy or momentum sources, PWs are generated in the model for zonal wavenumbers 1-4, which have amplitudes in the mesosphere above 50 km as large as 30 m/s and periods between 2 and 15 days. The waves are generated primarily during solstice, which indicates that the baroclinic instability (associated with the GW driven reversal in the latitudinal temperature gradient) plays an important role. Results from a numerical experiment show that GWs are also significantly involved directly in generating the PWs. For the zonal wavenumber m = 1, the predominant wave periods at mid latitudes in summer cover a wide range around 7 days and peak in winter around 4 days. For m = 2, the periods in summer and winter are around 4 and 3 days, respectively. For m = 3, 4 the predominant wave periods are in both seasons close to 2 days. At low latitudes, these waves have the characteristics of Rossby gravity waves, with large meridional winds at the equator and propagating westward. A common feature of the PWs (m = I to 4) generated in the summer and winter hemispheres is that their vertical wavelengths throughout the mesosphere are large, which indicates that the waves are not propagating freely but are generated (and absorbed) throughout the region. Another common feature is that the PWs propagate preferentially westward in summer and eastward in winter. being launched from the westward and eastward zonal winds that prevail, respectively, in the summer and winter hemispheres at altitudes below 80 km. As shown in Part 1, the PWs generated in the model produce large amplitude modulations of the diurnal and semi-diurnal tides above 80 km and contribute to their seasonal variations. (C) 2001 Published by Elsevier Science Ltd. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. Hong Kong Univ Sci & Technol, Hong Kong, Hong Kong, Peoples R China. Furman Univ, Greenville, SC 29613 USA. RP Mayr, HG (reprint author), NASA, Goddard Space Flight Ctr, MC 910-4, Greenbelt, MD 20771 USA. OI Chan, Kwing/0000-0002-6428-1812 NR 47 TC 14 Z9 15 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD NOV PY 2001 VL 63 IS 17 BP 1865 EP 1881 DI 10.1016/S1364-6826(01)00057-8 PG 17 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 491KD UT WOS:000172106800009 ER PT J AU Albyn, HC AF Albyn, HC TI Extension of the enthalpy of sublimation for adipic acid to temperatures below 80 degrees C SO JOURNAL OF CHEMICAL AND ENGINEERING DATA LA English DT Article AB The enthalpy of sublimation for adipic acid is available from several literature sources (Chemical Rubber Co. Handbook of Chemistry and Physics, 66th ed.; Chemical Rubber Publishing: Boca Raton, FL, 1985-1986. Configurational Thermal Vacuum Stability Test Method Development, TR-427-001; Lyndon B. Johnson Space Center, White Sands Test Facility, January 3, 1989. Afeedy, H. Y.; Liebman, J. F.; Stein, S. E. NIST Chemistry WebBook, NIST Standard Reference Database No. 69; NIST: Gaithersburg, MD, November 1998) for temperatures of greater than or equal to 80 degreesC. Those references generally cite the work of Davies and Thomas (Davies, M.; Thomas, G. Trans. Faraday Soc. 1960, 56, 185-192) on the lattice energy of dicarboxylic acids. Measurements made with a 15 MHz temperature-controlled quartz crystal microbalance demonstrate that the enthalpy of sublimation, (129 +/- 1.0) kJ.mol(-1), for adipic acid is constant in the range of 25 to 80 degreesC. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Albyn, HC (reprint author), NASA, Lyndon B Johnson Space Ctr, 2101 NASA Rd 1, Houston, TX 77058 USA. NR 6 TC 3 Z9 3 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0021-9568 J9 J CHEM ENG DATA JI J. Chem. Eng. Data PD NOV-DEC PY 2001 VL 46 IS 6 BP 1415 EP 1416 PG 2 WC Thermodynamics; Chemistry, Multidisciplinary; Engineering, Chemical SC Thermodynamics; Chemistry; Engineering GA 493VJ UT WOS:000172243900014 ER PT J AU Gutsev, GL Jena, P Zhai, HJ Wang, LS AF Gutsev, GL Jena, P Zhai, HJ Wang, LS TI Electronic structure of chromium oxides, CrOn- and CrOn (n=1-5) from photoelectron spectroscopy and density functional theory calculations SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID TRANSITION-METAL OXIDES; GAS-PHASE; INFRARED-SPECTRA; MONOXIDE ANIONS; NEGATIVE-ION; SOLID ARGON; CLUSTERS; ATOMS; EXCHANGE; 3D AB The electronic structure of CrOn- and CrOn (n=1-5) was investigated using anion photoelectron spectroscopy and density functional theory. Photoelectron spectra of CrOn- were obtained at several photon energies and yielded electron affinities, vibrational and electronic structure information about the neutral CrOn species. Density functional theory calculations were carried out for both the neutrals and anions and were used to interpret the experimental spectra. Several low-lying electronic states of CrO were observed and assigned from photodetachment of the CrO- ground state ((6)Sigma (+)) and an excited state ((4)Pi), which is only 0.1 eV higher. The main spectral features of CrO2- were interpreted based on a C-2v CrO2- (B-4(1)). A very weak Cr(O-2)(-) isomer was also observed with lower electron binding energies. Relatively simple and vibrationally resolved spectra were observed for CrO3-, which was determined to be D-3h. The CrO3 neutral was calculated to be C-3v with the Cr atom slightly out of the plane of the three O atoms. The spectrum of CrO4- revealed a very high electron binding energy. Several isomers of CrO4- were predicted and the ground state has a distorted tetrahedral structure (C-2) without any O-O bonding. Only one stable structure was predicted for CrO5- with a superoxo O-2 bonded to a C-3v CrO3. (C) 2001 American Institute of Physics. C1 Virginia Commonwealth Univ, Dept Phys, Richmond, VA 23284 USA. Washington State Univ, Dept Phys, Richland, WA 99352 USA. Pacific NW Natl Lab, WR Wiley Environm Mol Sci Lab, Richland, WA 99352 USA. RP Gutsev, GL (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 52 TC 85 Z9 88 U1 4 U2 20 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD NOV 1 PY 2001 VL 115 IS 17 BP 7935 EP 7944 DI 10.1063/1.1405438 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 483QU UT WOS:000171647900016 ER PT J AU Montero, RS Llorente, IM Salas, MD AF Montero, RS Llorente, IM Salas, MD TI Robust multigrid algorithms for the Navier-Stokes equations SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE plane-implicit smoothers; symmetric coupled Gauss-Seidel; robust multigrid; defect correction; Navier-Stokes ID CONVERGENCE; FLOW AB Anisotropies occur naturally in computational fluid dynamics where the simulation of small-scale physical phenomena, such as boundary layers at high Reynolds numbers, causes the grid to be highly stretched, leading to a slowdown in convergence of multigrid methods. Several approaches aimed at making multigrid a robust solver have been proposed and analyzed in the literature using the scalar diffusion equation. However, they have rarely been applied to solving more complicated models, such as the incompressible Navier-Stokes equations. This paper contains the first published numerical results of the behavior of two popular robust multigrid approaches (alternating-plane smoothers combined with standard coarsening and plane-implicit smoothers combined with semi-coarsening) for solving the 3-D incompressible Navier-Stokes equations in the simulation of the driven-cavity and a boundary layer over a flat plate on a stretched grid. Grid size, grid stretching, and Reynolds number are the factors considered in evaluating the robustness of the multigrid methods. Both approaches yield large increases in convergence rates over cell-implicit smoothers on stretched grids. The combination of plane-implicit smoothers and semi-coarsening was found to be fully robust in the flat-plate simulation up to Reynolds numbers 10(6) and the best alternative in the driven-cavity simulation for Reynolds numbers above 10(3). The alternating-plane approach exhibits a better behavior for lower Reynolds numbers (below 10(3)) in the driven-cavity simulation. (C) 2001 Academic Press. C1 Univ Complutense, Dept Arquitectura Computadores & Automat, E-28040 Madrid, Spain. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Montero, RS (reprint author), Univ Complutense, Dept Arquitectura Computadores & Automat, E-28040 Madrid, Spain. RI Martin Llorente, Ignacio/B-2093-2009; Montero, Ruben/C-5346-2008 OI Martin Llorente, Ignacio/0000-0001-6230-8180; Montero, Ruben/0000-0003-2591-1719 NR 24 TC 12 Z9 12 U1 0 U2 4 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD NOV 1 PY 2001 VL 173 IS 2 BP 412 EP 432 DI 10.1006/jcph.2001.6863 PG 21 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 490YK UT WOS:000172081100002 ER PT J AU DeMartini, EE Williams, HA AF DeMartini, EE Williams, HA TI Fecundity and egg size of Scyllarides squammosus (Decapoda : Scyllaridae) at Maro Reef, Northwestern Hawaiian Islands SO JOURNAL OF CRUSTACEAN BIOLOGY LA English DT Article ID PANULIRUS-MARGINATUS; SPINY LOBSTER AB The body size-specific fecundity of Scyllarides squammosus is described based on the numbers of eggs carried externally on the pleopods of "berried" (ovigerous) females collected during June 1999, at Maro Reef, located mid-chain in the Northwestern Hawaiian Islands (NWHI). Fecundity was positively and nonlinearly related to "tail" (abdomen) width (TW); fecundity ranged from 53,807 to 227,489 eggs in 43 females spanning 52-77-mm. TW. The smallest berried female encountered at Maro Reef in 1999 was larger than the smallest berried female observed during most previous years' (1986-97) lobster research cruises. Fecundity of the median-sized (60-mm TW) female caught at Maro Reef in 1999 by the NWHI commercial lobster trap fishery was an estimated 89,660 +/- 3,980 (SE) eggs. Brooded eggs averaged 0.67 +/- 0.006-mm diameter (range: 0.61-0.77 mm), equivalent to 0.17 and 0.13-0.24 mg, respectively. Egg size was unrelated to female body size. Fecundity and egg size estimates and their body size relationships are briefly compared with other scyllarid lobsters. C1 NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, Honolulu Lab, Honolulu, HI 96822 USA. RP DeMartini, EE (reprint author), NOAA, Natl Marine Fisheries Serv, SW Fisheries Sci Ctr, Honolulu Lab, 2570 Dole St, Honolulu, HI 96822 USA. NR 13 TC 14 Z9 15 U1 0 U2 3 PU CRUSTACEAN SOC PI SAN ANTONIO PA 840 EAST MULBERRY, SAN ANTONIO, TX 78212 USA SN 0278-0372 J9 J CRUSTACEAN BIOL JI J. Crustac. Biol. PD NOV PY 2001 VL 21 IS 4 BP 891 EP 896 DI 10.1651/0278-0372(2001)021[0891:FAESOS]2.0.CO;2 PG 6 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA 491NJ UT WOS:000172114500003 ER PT J AU Frazer, CS Dickey, EC Sayir, A AF Frazer, CS Dickey, EC Sayir, A TI Crystallographic texture and orientation variants in Al2O3-Y3Al5O12 directionally solidified eutectic crystals SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE characterization; directional solidification; eutectics; interfaces; floating zone technique; oxides ID MECHANICAL-PROPERTIES; THERMAL-STABILITY; COMPOSITE; MICROSTRUCTURE; BOUNDARIES AB Eutectic rods of Al2O3 and Y3Al5O12 were grown by a laser-heated float zone method, and their microstructure and crystallographic texture were studied by scanning electron microscopy, electron-backscattered diffraction and X-ray diffraction. The composites were found to be highly textured with two twin-related crystallographic orientation relationships between the phases. Electron-backscattered diffraction was employed to determine the spatial distribution of the orientational variants within the samples and to define the crystallographic orientation of various microstructural features. (C) 2001 Published by Elsevier Science B.V. C1 Penn State Univ, Dept Mat Sci & Engn, University Pk, PA 16802 USA. John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Dickey, EC (reprint author), Penn State Univ, Dept Mat Sci & Engn, 195 MRI Bldg, University Pk, PA 16802 USA. RI Dickey, Elizabeth/A-3368-2011 OI Dickey, Elizabeth/0000-0003-4005-7872 NR 25 TC 47 Z9 48 U1 1 U2 15 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 2001 VL 233 IS 1-2 BP 187 EP 195 DI 10.1016/S0022-0248(01)01590-1 PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 472LV UT WOS:000170986400026 ER PT J AU Yau, ST Thomas, BR Vekilov, PG AF Yau, ST Thomas, BR Vekilov, PG TI Real time, in-situ, monitoring of apoferritin crystallization and defect formation with molecular resolution SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 8th International Conference on Crystallization of Biological Macromolecules CY MAY 14-19, 2000 CL SANDESTIN, FLORIDA DE atomic force microscopy; biocrystallization; crystal morphology; impurities; point defects; biological macromolecules ID ATOMIC-FORCE MICROSCOPY; CRYSTAL-GROWTH; STEP DYNAMICS; PROTEIN CRYSTALLIZATION; SURFACE-MORPHOLOGY; LYSOZYME CRYSTAL; LAYER GROWTH; HUMAN-H; KINETICS; THERMODYNAMICS AB Using the atomic force microscope (AFM) in-situ during the crystallization of a model protein, we investigate the elementary processes of crystal growth at the molecular level. We show that the density of the incorporation sites (kinks) on growth steps propagating on the surface (i) is the same as at equilibrium, and (ii) does not depend on the macroscopic step orientation since during growth the steps consist of segments along the dense crystallographic directions. Observation (i) allows evaluation of the bond energy between molecules in the crystal as 3.2 k(B)T. Furthermore, we determine the frequency of attachment of molecules at the kinks and show that step motion is fully described by this frequency and the kink density. We monitor the formation of point defects and show that, unlike in semiconductors, they are caused by incorporation of impurity particles and therefore are nonequilibrial. The point defects replicate in subsequent layers due to the strain they cause. We demonstrate that using single-molecule manipulation with the AFM tip the defects can be "healed" to restore the regular lattice. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Alliance Micrograv Mat Res & Applicat, Huntsville, AL 35812 USA. Univ Alabama, Dept Chem, Huntsville, AL 35899 USA. NR 40 TC 7 Z9 8 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 2001 VL 232 IS 1-4 BP 188 EP 194 DI 10.1016/S0022-0248(01)01149-6 PG 7 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 473KL UT WOS:000171042700023 ER PT J AU Burke, MW Judge, RA Pusey, ML AF Burke, MW Judge, RA Pusey, ML TI The effect of solution thermal history on chicken egg white lysozyme nucleation SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 8th International Conference on Crystallization of Biological Macromolecules CY MAY 14-19, 2000 CL SANDESTIN, FLORIDA DE biocrystallization; nucleation; phase equilibria; biological macromolecules; lysozyme; proteins ID CRYSTAL-GROWTH; TETRAGONAL LYSOZYME; PROTEIN CRYSTALS; SOLUBILITY; TEMPERATURE; CRYSTALLIZATION; KINETICS; PH AB Proteins are highly flexible molecules and often exhibit defined conformational changes in response to changes in the ambient temperature. Chicken egg white lysozyme has been previously shown to undergo an apparent structural change when warmed above the tetragonal/orthorhombic phase transition temperature. This is reflected by a change in the habit of the tetragonal and orthorhombic crystals so formed. In this study, we show that possible conformational changes induced by heating are stable and apparently non-reversible by simple cooling. Exposure of protein solutions to temperatures above the phase change transition temperature, before combining with precipitant solution to begin crystallization, reduces final crystal numbers. Protein that is briefly warmed to 37 degreesC, then cooled shows no sign of reversal to the unheated nucleation behavior even after storage for 4 weeks at 4 degreesC. The change in nucleation behavior of tetragonal lysozyme crystals, attributed to a structural shift, occurs faster the greater the exposure to temperature above the equi-solubility point for the two phases. Heating for 2 It at 48 degreesC reduces crystal numbers by 20 fold in comparison to the same solution heated for the same time at 30 degreesC. Thermal treatment of solutions is therefore a possible tool to reduce crystal numbers and increase crystal size. The effects of a protein's previous thermal history are now shown to be a potentially critical factor in subsequent macromolecule crystal nucleation and growth studies. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Huntsville, AL 35899 USA. RP Pusey, ML (reprint author), NASA, George C Marshall Space Flight Ctr, Biophys SD48, Huntsville, AL 35812 USA. NR 30 TC 16 Z9 16 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 2001 VL 232 IS 1-4 BP 301 EP 307 DI 10.1016/S0022-0248(01)01060-0 PG 7 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 473KL UT WOS:000171042700038 ER PT J AU Sumida, JP Forsythe, EL Pusey, ML AF Sumida, JP Forsythe, EL Pusey, ML TI Preparation and preliminary characterization of crystallizing fluorescent derivatives of chicken egg white lysozyme SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 8th International Conference on Crystallization of Biological Macromolecules CY MAY 14-19, 2000 CL SANDESTIN, FLORIDA DE biocrystallization; characterization; nucleation; biological macromolecules; lysozyme; proteins ID ANISOTROPY AB Fluorescence is one of the most versatile and powerful tools for the study of macromolecules. While most proteins are intrinsically fluorescent, working at crystallization concentrations require the use of covalently prepared derivatives added as tracers. This approach requires derivatives that do not markedly affect the crystal packing. We have prepared fluorescent derivatives of chicken egg white lysozyme with probes bound to one of two different sites on the protein molecule. Lucifer yellow and 5-(2-aminoethyl)aminonapthalene-1-sulfonic acid (EDANS) have been attached to the side chain carboxyl of Asp(101) using a carbodiimide coupling procedure. Asp(101) lies within the active site cleft, and it is believed that the probes are "buried" within that cleft. Lucifer yellow and EDANS probes with iodoacetamide reactive groups have been bound to His(15), located on the "back side" of the molecule relative to the active site. All the derivatives fluoresce in the solution and the crystalline states. Fluorescence characterization has focused on determination of binding effects on the probe quantum yield, lifetime, absorption and emission spectra, and quenching by added solutes. Quenching studies show that, as postulated, the Asp(101)-bound probes are partially sheltered from the bulk solution by their location within the active site cleft. Probes bound to His(15) have quenching constants about equal to those for the free probes, indicating that this site is highly exposed to the bulk solution. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. USRA, Huntsville, AL 35806 USA. RP Pusey, ML (reprint author), NASA, George C Marshall Space Flight Ctr, Biophys SD48, Huntsville, AL 35812 USA. NR 17 TC 8 Z9 9 U1 0 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 2001 VL 232 IS 1-4 BP 308 EP 316 DI 10.1016/S0022-0248(01)01061-2 PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 473KL UT WOS:000171042700039 ER PT J AU Serrano, MD Galkin, O Yau, ST Thomas, BR Nagel, RL Hirsch, RE Vekilov, PG AF Serrano, MD Galkin, O Yau, ST Thomas, BR Nagel, RL Hirsch, RE Vekilov, PG TI Are protein crystallization mechanisms relevant to understanding and control of polymerization of deoxyhemoglobin S? SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 8th International Conference on Crystallization of Biological Macromolecules CY MAY 14-19, 2000 CL SANDESTIN, FLORIDA DE atomic force microscopy; biocrystallization; phase diagrams; biological macromolecules ID SICKLE-CELL HEMOGLOBIN; LIQUID PHASE-SEPARATION; 3-DIMENSIONAL RECONSTRUCTION; CRYSTAL NUCLEATION; FETAL HEMOGLOBIN; KINETICS; HYDROXYUREA; GELATION; DISEASE; ANEMIA AB We investigated the homogeneous nucleation and subsequent evolution of polymers of sickle cell hemoglobin (HbS) using differential interference contrast (DIC) microscopy. The same technique was employed to determine the liquid liquid separation boundaries for a variety of conditions in solution of sickle cell and normal human hemoglobin. The HbS polymers were also imaged using atomic force microscopy. We found that the location of Liquid-Liquid phase boundary under conditions that mimic those in the erythrocytes is consistent with previous determinations of the spinodal for this phase transition. Increasing the ionic strength shifts this phase boundary to significantly lower temperatures and fib concentrations. We also found that the nucleation of individual HbS fibers indicates that the process is random and follows statistics similar to those established for nucleation of crystals or liquid droplets from vapors. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Alabama, Ctr Micrograv & Mat Res, Huntsville, AL 35899 USA. Univ Autonoma Madrid, Dept Fis Mat, E-28049 Madrid, Spain. Univ Space Res Assoc, George C Marshall Space Flight Ctr, Huntsville, AL 35875 USA. Albert Einstein Coll Med, Div Hematol, Dept Med, Bronx, NY 10467 USA. Albert Einstein Coll Med, Dept Physiol & Biophys, Bronx, NY 10467 USA. Albert Einstein Coll Med, Dept Anat & Struct Biol, Bronx, NY 10467 USA. Univ Alabama, Dept Chem, Huntsville, AL 35899 USA. RP Vekilov, PG (reprint author), Univ Alabama, Ctr Micrograv & Mat Res, Huntsville, AL 35899 USA. RI Serrano, Maria Dolores/B-9629-2013 NR 51 TC 10 Z9 10 U1 0 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 2001 VL 232 IS 1-4 BP 368 EP 375 DI 10.1016/S0022-0248(01)01068-5 PG 8 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 473KL UT WOS:000171042700046 ER PT J AU Cannone, JJ Barnes, CL Achari, A Kundrot, CE AF Cannone, JJ Barnes, CL Achari, A Kundrot, CE TI Crystallization of bFGF-DNA aptamer complexes using a Sparse Matrix designed for protein-nucleic acid complexes SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 8th International Conference on Crystallization of Biological Macromolecules CY MAY 14-19, 2000 CL SANDESTIN, FLORIDA DE biocrystallization; biological macromolecules ID FIBROBLAST GROWTH-FACTOR; TRANSFER-RNA-SYNTHETASE; REPRESSOR-OPERATOR COMPLEX; ANGSTROM CRYSTAL-STRUCTURE; X-RAY ANALYSIS; BINDING DOMAIN; CRYSTALLOGRAPHIC ANALYSIS; 3-DIMENSIONAL STRUCTURE; THERMUS-THERMOPHILUS; PHAGE-434 REPRESSOR AB The Sparse Matrix approach for obtaining lead crystallization conditions has proven to be very fruitful for the crystallization of proteins and nucleic acids. Here we report a Sparse Matrix developed specifically for the crystallization of protein-DNA complexes. This method is rapid and economical, typically requiring 2.5 mg of complex to test 48 conditions. The method was originally developed to crystallize basic fibroblast growth factor (bFGF) complexed with DNA sequences identified through in vitro selection, or SELEX, methods. Two DNA aptamers that bind with approximately nanomolar affinity and inhibit the angiogenic properties of bFGF were selected for cocrystallization. The Sparse Matrix produced lead crystallization conditions for both bFGF-DNA complexes. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Texas, Dept Cellular & Mol Biol, Austin, TX 78712 USA. USRA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Kundrot, CE (reprint author), NASA, George C Marshall Space Flight Ctr, Mail Code SD48, Huntsville, AL 35812 USA. NR 84 TC 0 Z9 0 U1 1 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 2001 VL 232 IS 1-4 BP 409 EP 417 DI 10.1016/S0022-0248(01)01094-6 PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 473KL UT WOS:000171042700050 ER PT J AU Karpova, EA Tarahovsky, YS AF Karpova, EA Tarahovsky, YS TI Altering the morphology of crystals of a macromolecule without changing the unit cell - (A case study of ribosome crystals) SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 8th International Conference on Crystallization of Biological Macromolecules CY MAY 14-19, 2000 CL SANDESTIN, FLORIDA DE crystal morphology; crystal structure; electron microscopy; nucleation; growth form solutions; ribosome ID CRYSTALLIZATION AB Crystals of different morphology (needle-, rod-tetragonal- and wedge-shaped) were grown from the same solution of ribosome and in the same drop using 10-15% 2-methyl-2,4-pentanediol as a precipitant. The crystals appeared in 5-48 h. Observations of the kinetics of crystal appearance lead to the conclusion that higher supersaturation of ribosome solution produces needle-shaped crystals, while the tetragonal-rod- and the wedge-shaped crystals grow at lower supersaturation. The ribosome packing in the crystals was characterized by electron microscopy (EM). An analysis of EM ultrathin sections indicates that the unit cells, with a high degree of probability, are the same in the needle-shaped and other morphology crystals. The data obtained suggest that adjusting supersaturation of the crystallization solution may convert needle-shaped to more useful morphologies. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, MSFC, Huntsville, AL 35812 USA. Russian Acad Sci, Inst Theoret & Expt Biophys, Pushchino 142292, Moscow Region, Russia. RP Karpova, EA (reprint author), New Century Pharmaceut Inc, 895 Martin Rd, Huntsville, AL 35824 USA. NR 13 TC 0 Z9 0 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 2001 VL 232 IS 1-4 BP 610 EP 617 DI 10.1016/S0022-0248(01)01087-9 PG 8 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 473KL UT WOS:000171042700075 ER PT J AU Kaiser, N Croll, A Szofran, FR Cobb, SD Benz, KW AF Kaiser, N Croll, A Szofran, FR Cobb, SD Benz, KW TI Wetting angle and surface tension of germanium melts on different substrate materials SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE surface tension; wetting angle; semiconducting germanium ID THERMOPHYSICAL PROPERTIES; DETACHED SOLIDIFICATION; MOLTEN GERMANIUM; BRIDGMAN GROWTH AB The sessile drop technique has been used to measure the wetting angle and the surface tension of molten germanium (Ge) on various substrate materials. Sapphire, fused silica, glassy carbon, graphite, SiC, carbon-based aerogel, pyrolytic boron nitride (pBN), AlN, Si3N4, and CVD diamond were used as substrate materials. In addition, the effects of different cleaning procedures and surface treatments on the wetting behavior were investigated. The highest wetting angles with values around 170 degrees were found for pBN substrates under active vacuum or with a slight overpressure of 5 N argon or forming g-as (2% hydrogen in 5N argon). The measurement of the surface tension and its temperature dependence for Ge under a forming gas atmosphere resulted in gamma (T) = 591 - 0.08 (T - T-m)[10(-3)N/m]. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Freiburg, Inst Kristallog, D-79104 Freiburg, Germany. NASA, George C Marshall Space Flight Ctr, AMMSA, Huntsville, AL 35812 USA. Univ Freiberg, Inst NE Met & Reinstoffe, D-09599 Freiberg, Germany. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Kaiser, N (reprint author), Univ Freiburg, Inst Kristallog, Hebelstr 25, D-79104 Freiburg, Germany. RI Croell, Arne/A-2480-2013 OI Croell, Arne/0000-0002-8673-9994 NR 23 TC 49 Z9 51 U1 6 U2 17 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 2001 VL 231 IS 4 BP 448 EP 457 DI 10.1016/S0022-0248(01)01480-4 PG 10 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 472BH UT WOS:000170962800003 ER PT J AU Ortiz, RM AF Ortiz, RM TI Osmoregulation in marine mammals. (vol 204, pg 1831, 2001) SO JOURNAL OF EXPERIMENTAL BIOLOGY LA English DT Correction DE kidney; urine; water; feeding; fasting; diving; salinity; drinking; aldosterone; vasopressin; angiotensin ID ELEPHANT SEAL PUPS; MANATEES TRICHECHUS-MANATUS; WATER FLUX; MIROUNGA-ANGUSTIROSTRIS; PLASMA VASOPRESSIN; PHOCA-GROENLANDICA; POSTWEANING FAST; NASAL HEAT; GRAY SEALS; EXCHANGE AB Osmoregulation in marine mammals has been investigated for over a century; however, a review of recent advances in our understanding of water and electrolyte balance and of renal function in marine mammals is warranted. The following topics are discussed: (i) kidney structure and urine concentrating ability, (il) sources of water, (iii) the effects of feeding, fasting and diving, (iv) the renal responses to infusions of varying salinity and (v) hormonal regulation. The kidneys of pinnipeds and cetaceans are reniculate in structure, unlike those of terrestrial mammals (except bears), but this difference does not confer any greater concentrating ability. Pinnipeds, cetaceans, manatees and sea otters can concentrate their urine above the concentration of sea water, but only pinnipeds and otters have been shown to produce urine concentrations of Na+ and Cl- that are similar to those in sea water. This could afford them the capacity to drink sea water and not lose fresh water. However, with few exceptions, drinking is not a common behavior in pinnipeds and cetaceans. Water balance is maintained in these animals via metabolic and dietary water, while incidental ingestion and dietary salt may help maintain electrolyte homeostasis. Unlike most other aquatic mammals, sea otters commonly drink sea water and manatees frequently drink fresh water. Among the various taxonomic groups of marine mammals, the sensitivity of the renin-angiotensin-aldosterone system appears to be influenced by the availability of Na+. The antidiuretic role of vasopressin remains inconclusive in marine mammals, while the natriuretic function of atrial natriuretic peptide has yet to be examined. Ideas on the direction of future studies are presented. C1 Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. NASA, Ames Res Ctr, Neuroendocrinol Lab, Div Life Sci, Stanford, CA 94305 USA. RP Ortiz, RM (reprint author), Univ Calif Santa Cruz, Dept Biol, A316 Earth & Marine Sci, Santa Cruz, CA 95064 USA. NR 95 TC 0 Z9 0 U1 5 U2 16 PU COMPANY OF BIOLOGISTS LTD PI CAMBRIDGE PA BIDDER BUILDING CAMBRIDGE COMMERCIAL PARK COWLEY RD, CAMBRIDGE CB4 4DL, CAMBS, ENGLAND SN 0022-0949 J9 J EXP BIOL JI J. Exp. Biol. PD NOV PY 2001 VL 204 IS 21 BP U1 EP + PG 15 WC Biology SC Life Sciences & Biomedicine - Other Topics GA 494WY UT WOS:000172309900001 ER PT J AU Kuang, D Bar-Sever, YE Bertiger, WI Hurst, KJ Zumberge, JF AF Kuang, D Bar-Sever, YE Bertiger, WI Hurst, KJ Zumberge, JF TI GPS-assisted GLONASS orbit determination SO JOURNAL OF GEODESY LA English DT Article DE GPS; GLONASS; orbit AB Using 1 week of data from a network of GPS/ GLONASS dual-tracking receivers, 15-cm accurate GLONASS orbit determination is demonstrated with an approach that combines GPS and GLONASS data. GPS data are used to define the reference frame, synchronize receiver clocks and determine troposphere delay for the GLONASS tracking network. GLONASS tracking data are then processed separately, with the GPS-defined parameters held fixed, to determine the GLONASS orbit. The quality of the GLONASS orbit determination is currently limited by the size and distribution of the tracking network, and by the unavailability of a sufficiently. refined solar pressure model. Temporal variations in the differential clock bias of the dual-tracking receivers are found to have secondary impact on the orbit determination accuracy. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kuang, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 7 Z9 8 U1 1 U2 7 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0949-7714 J9 J GEODESY JI J. Geodesy PD NOV PY 2001 VL 75 IS 11 BP 569 EP 574 DI 10.1007/s001900100180 PG 6 WC Geochemistry & Geophysics; Remote Sensing SC Geochemistry & Geophysics; Remote Sensing GA 503LZ UT WOS:000172801100003 ER PT J AU Suhasini, R Raghavarao, R Mayr, HG Hoegy, WR Wharton, LE AF Suhasini, R Raghavarao, R Mayr, HG Hoegy, WR Wharton, LE TI Equatorial temperature anomaly during solar minimum SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID THERMOSPHERE; MAXIMUM; ETWA AB We show evidence for the occurrence of the equatorial temperature anomaly (ETA) during solar minimum by analyzing the temperature and total ion density data from the Neutral Atmosphere Temperature Experiment (NATE) and the Cylindrical Electrostatic Probe (CEP), respectively, on board the Atmospheric Explorer-E satellite. The chosen data refer to a height of similar to 254 km in the African and Asian longitude sector (340, I degreesE-200 degreesE) during a summer season in the Southern Hemisphere. As during the solar maximum period, the spatial characteristics of the ETA are similar to those of the equatorial ionization anomaly (EIA). A minimum in the gas temperature is collocated with the minimum in the ion density at the dip equator, and a temperature maximum on the south side of the equator is collocated with the density maximum of the EIA. The daytime behavior of ETA formation is about the same as that of EIA as both of them are clearly present at around 1300 and 1400 local solar time (LST) only. At 1400 LST the difference between the temperatures at the crest and the trough (ETA strength) reaches a maximum value of about 100 degreesK which is similar to 14% of the temperature at the trough. Like the EIA, the ETA also suddenly disappears after 1400 LST, Thus the EIA appears to be a prerequisite for the ETA formation. During the premidnight time (2200 LST), however, while the EIA is nonexistent, the temperature distribution forms a pattern opposite to that at 1400 LST in the daytime. It shows a maximum around the dip equator and a broad minimum at the daytime crest region where the postsunset cooling also is faster and occurs earlier than at the dip equator. This nighttime maximum appears to be related to the signature of the midnight temperature maximum (MTM). Mass Spectrometer Incoherent Scatter (MSIS) model temperatures, in general, are higher than the observed average temperatures for the summer season and in particular for the region around the dip equator around noon hours. C1 Nitya Labs Ltd, Hyderabad 500082, Andhra Pradesh, India. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Suhasini, R (reprint author), Nitya Labs Ltd, G-3,Shirdi Apartments,Plot 4 Somajiguda, Hyderabad 500082, Andhra Pradesh, India. NR 15 TC 10 Z9 10 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 24777 EP 24783 DI 10.1029/2001JA900089 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300023 ER PT J AU Cravens, TE Robertson, IP Snowden, SL AF Cravens, TE Robertson, IP Snowden, SL TI Temporal variations of geocoronal and heliospheric X-ray emission associated with the solar wind interaction with neutrals SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EXTREME-ULTRAVIOLET EMISSION; ALL-SKY SURVEY; COMET HYAKUTAKE; CHARGE-TRANSFER; HALE-BOPP; IONS; EXCHANGE; MOON; EUVE AB X-ray emission due to charge transfer collisions between heavy solar wind ions and neutrals has been predicted to exist both in the heliosphere and in the geocorona. The heliospheric X-ray emission can account for roughly half of the observed soft X-ray background intensity. It was also suggested that temporal variations in the heliospheric and geocoronal soft X-ray intensities will result from solar wind variations. In this paper, a simple model of the charge exchange X-ray emission mechanism is combined with measured solar wind parameters as a function of time and used to generate predictions of the temporal variation of the X-ray intensity observed at Earth for the time periods 1990-1993 and 1996-1998. Measured solar wind proton fluxes are also directly compared with the "long-term enhancement" part of the soft X-ray background measured by the Rontgen Satellite (ROSAT). A significant positive correlation exists, which supports the existence of X-ray emission associated with the solar wind interaction with either interstellar neutrals and/or with geocoronal neutral hydrogen. C1 Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Cravens, TE (reprint author), Univ Kansas, Dept Phys & Astron, Malott Hall, Lawrence, KS 66045 USA. EM cravens@ukans.edu; robertin@ukans.edu; snowden@heavx.gsfc.nasa.gov RI Snowden, Steven/D-5292-2012 NR 40 TC 107 Z9 107 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 24883 EP 24892 DI 10.1029/2000JA000461 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300032 ER PT J AU Collier, MR Moore, TE Ogilvie, KW Chornay, D Keller, JW Boardsen, S Burch, J El Marji, B Fok, MC Fuselier, SA Ghielmetti, AG Giles, BL Hamilton, DC Peko, BL Quinn, JM Roelof, EC Stephen, TM Wilson, GR Wurz, P AF Collier, MR Moore, TE Ogilvie, KW Chornay, D Keller, JW Boardsen, S Burch, J El Marji, B Fok, MC Fuselier, SA Ghielmetti, AG Giles, BL Hamilton, DC Peko, BL Quinn, JM Roelof, EC Stephen, TM Wilson, GR Wurz, P TI Observations of neutral atoms from the solar wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MICROCHANNEL PLATE; GEOMAGNETIC STORMS; 3-DIMENSIONAL MHD; ION DISTRIBUTIONS; CHARGE-EXCHANGE; MAGNETIC-FIELD; HYDROGEN FLUX; PLASMA FLOW; SPACE; ENERGY AB We report observations of neutral atoms from the solar wind in the Earth's vicinity with the low-energy neutral atom (LENA) imager on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft. This instrument was designed to be capable of looking at and in the direction of the Sun. Enhancements in the hydrogen count rate in the solar direction are not correlated with either solar ultraviolet emission or suprathermal ions and are deduced to be due to neutral particles from the solar wind. LENA observes these particles from the direction closest to that of the Sun even when the Sun is not directly in LENA's 90 degrees field of view. Simulations show that these neutrals are the result of solar wind ions charge exchanging with exospheric neutral hydrogen atoms in the postshock flow of the solar wind in the magnetosheath. Their energy is inferred to exceed 300 eV, consistent with solar wind energies, based on simulation results and on the observation of oxygen ions, sputtered from the conversion surface in the time-of-flight spectra. In addition, the sputtered oxygen abundance tracks the solar wind speed, even when IMAGE is deep inside the magnetosphere. These results show that low-energy neutral atom imaging provides the capability to directly monitor the solar wind flow in the magnetosheath from inside the magnetosphere because there is a continuous and significant flux of neutral atoms originating from the solar wind that permeates the magnetosphere. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Raytheon ITSS Corp, Lanham, MD USA. SW Res Inst, San Antonio, TX 78228 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. Univ Denver, Dept Phys & Astron, Denver, CO 80208 USA. Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Mission Res Corp, Nashua, NH 03062 USA. Univ Bern, Inst Phys, CH-3012 Bern, Switzerland. RP Collier, MR (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM mcollier@pop600.gsfc.nasa.gov RI Moore, Thomas/D-4675-2012; Fok, Mei-Ching/D-1626-2012; Keller, John/I-5097-2013; Collier, Michael/I-4864-2013; OI Moore, Thomas/0000-0002-3150-1137; Collier, Michael/0000-0001-9658-6605; Hamilton, Douglas/0000-0001-6103-8019 NR 45 TC 52 Z9 52 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 24893 EP 24906 DI 10.1029/2000JA000382 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300033 ER PT J AU Burlaga, LF Harvey, KL Sheeley, NR AF Burlaga, LF Harvey, KL Sheeley, NR TI A transitory corotating stream, a short-lived coronal hole, and related magnetic fields SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID STRUCTURED SOLAR-WIND; 3-DIMENSIONAL PROPAGATION; FLUX TRANSPORT; MASS EJECTIONS; ORIGIN; INTERFACES; EVOLUTION; MINIMUM; ULYSSES; PLASMA AB We discuss some implications of the finite lifetime of a short-lived near-equatorial coronal hole for the structure of a corresponding transitory corotating stream and magnetic field in the heliosphere. The discussion is based on the illustrative example of a corotating stream that was observed by the Wind spacecraft in the ecliptic at 1 AU in early 1998 and the associated solar observations. The transitory corotating stream was associated with a near-equatorial coronal hole that formed, persisted for at least two solar rotations, and disappeared, all in response to the magnetic flux in evolving active regions. The corotating stream recurred for two solar rotations, and its emission time, based on the coronal hole observations, was approximate to 66 +/- 6 days. The intersection of the resulting corotating stream with the ecliptic plane has the form of a spiral-shaped object with a radial extent on the order of 19 +/- 2 AU. The magnetic field configurations in transitory corotating streams are not known. One possibility is that the transitory corotating stream originates from a localized near-equatorial coronal hole, possibly a member of a pair of coronal holes, joined by a flux tube, which evolve together. Such a transitory corotating stream could carry the flux tube through the corona and heliosphere. Another possibility is that the transitory corotating stream is the result of the latitudinal motion and deformation of the boundary of a polar coronal hole and the associated redistribution of a constant amount of open magnetic flux. Models and further observations of transitory corotating streams and their magnetic fields are needed in order to better understand them. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Solar Phys Res Corp, Tucson, AZ 85718 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. RP Burlaga, LF (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Code 692,Bldg 2,Room 127, Greenbelt, MD 20771 USA. EM burlaga@lepvax.gsfc.nasa.gov; kharvey@sprchq.com; sheeley@spruce.nrl.navy.mil NR 41 TC 5 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 24915 EP 24922 DI 10.1029/2001JA000043 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300035 ER PT J AU Gary, SP Goldstein, BE Steinberg, JT AF Gary, SP Goldstein, BE Steinberg, JT TI Helium ion acceleration and heating by Alfven/cyclotron fluctuations in the solar wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ALFVEN WAVES; CYCLOTRON-RESONANCE; ALPHA-PARTICLES; CORONAL HOLES; HEAVY-IONS; INSTABILITIES; DISSIPATION; ANISOTROPY; PROTONS; PLASMA AB The interaction between alpha particles and a given magnetic power Spectrum of Alfven/cyclotron fluctuations at propagation parallel to the background magnetic field B-o is examined in a model of a homogeneous, collisionless, magnetized plasma. Exact solutions of the linear Vlasov dispersion equation and second-order theory are used to calculate the wave-particle scattering rates for alpha/proton momentum exchange as well as for proton and alpha heating and anisotropy change. It is well established that alpha velocities are not observed to oscillate when the alpha/proton relative flow speed parallel to B-o matches the phase speed of long-wavelength Alfven waves, the "surfing" speed. Second-order theory predicts that wave-particle scattering is dominated by the relatively short wavelength, relatively low phase speed Alfven/cyclotron fluctuations which have a strong cyclotron resonance with the alphas. Thus the theory predicts that at sufficiently high proton beta the average alpha/proton speed should be observed to be substantially smaller than the surfing speed associated with long-wavelength fluctuations. C1 Los Alamos Natl Lab, Los Alamos, NM 87545 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gary, SP (reprint author), Los Alamos Natl Lab, MS D466, Los Alamos, NM 87545 USA. NR 40 TC 24 Z9 25 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 24955 EP 24963 DI 10.1029/2001JA000059 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300038 ER PT J AU Wu, ST Zheng, HN Wang, S Thompson, BJ Plunkett, SP Zhao, XP Dryer, M AF Wu, ST Zheng, HN Wang, S Thompson, BJ Plunkett, SP Zhao, XP Dryer, M TI Three-dimensional numerical simulation of MHD waves observed by the Extreme Ultraviolet Imaging Telescope SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTION; EULERIAN FICE SCHEME; SOHO/EIT OBSERVATIONS; TRANSIENT; FLOWS AB We investigate the global large amplitude waves propagating across the solar disk as observed by the SOHO/Extreme Ultraviolet Imaging Telescope (EIT). These waves appear to be similar to those observed in H-alpha in the chromosphere and which are known as "Moreton waves," associated with large solar flares [Moreton, 1960, 1964]. Uchida [1968] interpreted these Moreton waves as the propagation of a hydromagnetic disturbance in the corona with its wavefront intersecting the chromosphere to produce the Moreton wave as observed in movie sequences of H-alpha images. To search for an understanding of the physical characteristics of these newly observed EIT waves, we constructed a three-dimensional, time-dependent, numerical magnetohydrodynamic (MHD) model. Measured global magnetic fields, obtained from the Wilcox Solar Observatory (WSO) at Stanford University, are used as the initial magnetic field to investigate hydromagnetic wave propagation in a three-dimensional spherical geometry. Using magnetohydrodynamic wave theory together with simulation, we are able to identify these observed EIT waves as fast mode MHD waves dominated by the acoustic mode, called magnetosonic waves. The results to be presented include the following: (1) comparison of observed and simulated morphology projected on the disk and the distance-time curves on the solar disk; (2) three-dimensional evolution of the disturbed magnetic field lines at various viewing angles; (3) evolution of the plasma density profile at a specific location as a function of latitude; and (4) computed Friedrich's diagrams to identify the MHD wave characteristics. C1 Univ Alabama, Ctr Space Plasma & Aeron Res, Huntsville, AL 35899 USA. Univ Alabama, Dept Mech Engn, Huntsville, AL 35899 USA. Univ Sci & Technol China, Dept Earth & Space Sci, Hefei 230026, Anhui, Peoples R China. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Washington, DC USA. Stanford Univ, Hansen Expt Phys Lab, Stanford, CA 94305 USA. NOAA, SEC, Boulder, CO 80305 USA. Explorat Phys Int Inc, Milford, NH USA. RP Wu, ST (reprint author), Univ Alabama, Ctr Space Plasma & Aeron Res, Huntsville, AL 35899 USA. RI Zheng, Huinan/A-1619-2010; Thompson, Barbara/C-9429-2012 NR 29 TC 133 Z9 137 U1 2 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25089 EP 25102 DI 10.1029/2000JA000447 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300048 ER PT J AU Li, Y Luhmann, JG Mulligan, T Hoeksema, JT Arge, CN Plunkett, SP St Cyr, OC AF Li, Y Luhmann, JG Mulligan, T Hoeksema, JT Arge, CN Plunkett, SP St Cyr, OC TI Earthward directed CMEs seen in large-scale coronal magnetic field changes, SOHO LASCO coronagraph and solar wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID WHOLE-SUN-MONTH; HELIOSPHERIC CURRENT SHEET; MASS EJECTIONS; CLOUDS; RECONNECTION; DISRUPTION; EVOLUTION; STREAMER; CYCLE AB One picture of coronal mass ejection (CME) initiation relates these events to the expansion into space of previously closed coronal magnetic fields, often part of the helmet streamer belt. The work described here makes use of the potential field source surface model based on updated synoptic photospheric field maps to study the large-scale coronal field changes. We isolate those field lines that change from closed to open configurations (newly opening field lines) by comparing potential field source surface models from adjacent magnetograph observations, wherein the same starting foot points on the photosphere are used. If there are some newly opening field lines between the times of two maps, we assume there was a possibility for CME occurrence(s) between these times. In particular, if there are newly opening field lines near the solar disk center, an earthward directed CME may have been generated. Monitoring the coronal magnetic field behavior can in principle reinforce (or not) days in advance predictions of magnetic storms based on Solar and Heliospheric Observatory (SOHO) Large-Angle Spectrometric Coronagraph (LASCO) halo CMEs. Moreover, the coronal field over the visible hemisphere contains information about the possible geoeffectiveness of a particular CME because it shows the approximate orientation and location of the active arcades. By comparing halo CMEs with the newly opening field lines, the solar wind measurements from Wind and ACE spacecraft and the Dst index, we show that, like soft X-ray sigmoids, disappearing filaments, and Extreme ultraviolet Imaging Telescope (EIT) waves on the disk of the Sun, magnetograph observation-based coronal field models may provide additional information on the likelihood of CME effects at the Earth. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA. Stanford Univ, Ctr Space Sci & Astrophys, Stanford, CA 94305 USA. NOAA, Boulder, CO 80303 USA. Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80303 USA. Space Environm Ctr, Boulder, CO USA. Catholic Univ Amer, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Computat Phys Inc, Greenbelt, MD USA. RP Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. EM yanli@ssl.berkeley.edu; jgluhman@ssl.berkeley.edu; tamitha@igpp.ucla.edu; todd@quake.stanford.edu; nick@argel.nosa.gov; kett@ajcannon.nascom.nasa.gov; stcyr@cua.edu NR 40 TC 17 Z9 17 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25103 EP 25120 DI 10.1029/2001JA900041 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300049 ER PT J AU Gopalswamy, N AF Gopalswamy, N TI Introduction to special section: Global picture of solar eruptive events SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Editorial Material ID CORONAL MASS EJECTIONS; INTERPLANETARY SHOCKS; WIND SPACECRAFT; RADIO; ORIGIN; DISTURBANCES; PROMINENCES; BURSTS; WAVES; MHZ AB This introduction highlights some of the scientific results reported in this special section on solar eruptive events and provides a brief description of issues related to the new results. Most of these papers grew out of the coordinated data analysis workshop held at the Goddard Space Flight Center during April 27-30, 1999, and the subsequent International Conference on Solar Eruptive Events held at the Catholic University of America, Washington, D. C. during March 6-9, 2000. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. RP Gopalswamy, N (reprint author), NASA, Goddard Space Flight Ctr, Bldg 26,Room G1,Mail Stop 682-3, Greenbelt, MD 20771 USA. RI Gopalswamy, Nat/D-3659-2012 NR 29 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25135 EP 25139 DI 10.1029/2001JA000071 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300053 ER PT J AU Falconer, DA AF Falconer, DA TI A prospective method for predicting coronal mass ejections from vector magnetograms SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR ACTIVE REGIONS; ELECTRIC CURRENTS; FIELD; LINES; SHEAR AB Two quantitative measures of the global nonpotentiality of predominantly bipolar active regions are explored for their usefulness as indicators of whether an active region is likely to produce coronal mass ejections (CMEs). The two measures, length of strong-field strong-shear main neutral line (L-SS) and global net current (I-N), are obtained directly from vector magnetograms of the regions. From measurements of L-SS and I-N in four active regions for which the global nonpotentiality and CME productivity are assessed independently of L-SS and I-N, it appears that L-SS and I-N are each a useful indicator of an active region's likely CME productivity. The results also suggest that L-SS and I-N may be more reliable predictors of the CME productivity of active regions than is the presence or absence of sigmoidal structure in coronal X-ray images of the regions and that there might be threshold values of L-SS and I-N above which CME production is likely and below which CME production is unlikely. While these results need to be certified by an expansion of this pilot study to more active regions, they show the promise of L-SS and I-N as quantitative measures of global nonpotentiality for CME prediction. C1 George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RP Falconer, DA (reprint author), George C Marshall Space Flight Ctr, Dept Space Sci, SD50, Huntsville, AL 35812 USA. NR 14 TC 48 Z9 48 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25185 EP 25190 DI 10.1029/2000JA004005 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300057 ER PT J AU Neupert, WM Thompson, BJ Gurman, JB Plunkett, SP AF Neupert, WM Thompson, BJ Gurman, JB Plunkett, SP TI Eruption and acceleration of flare-associated coronal mass ejection loops in the low corona SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOHO EIT OBSERVATIONS; X-RAY; SOLAR ERUPTIONS; SUN; TRANSIENT; LASCO; WAVES AB Observations made by the EUV imaging telescope (EIT) and the Large-Angle Spectrometric Coronagraph (LASCO) on board the Solar Heliospheric Observatory (SOHO) have been used to characterize the eruption and acceleration of flare-associated coronal mass ejections (CMEs) in the low corona. For three well-observed limb events we tracked CME loops back to preexisting but faint EUV-emitting loops at heights of 100-250 Min that initially brightened slowly and possibly increased slowly in height, apparently in response to filament activity and eruption in the associated active regions. Subsequent CME acceleration coincided with a rapid rise of the soft X-ray flux, occurred between 100 and 350 Mm above the surface, and may have been as high as 0.5 km s(-1) s(-1), consistent with an impulsive acceleration of the CME to the speeds observed in subsequent white-light observations. The existence of a delay of up to 30 min observed between initial filament eruption in H alpha and subsequent high acceleration of the CME in one event implies that there may have been two separate phases of magnetic reconnection, with the initial filament activity acting as a trigger for subsequent CME and energetic particle acceleration in the impulsive stage of the flare. The presence or absence of this impulsive phase may provide a basis for the two types of CMEs that have been discussed in the literature. C1 NOAA, Space Environm Ctr, Boulder, CO 80303 USA. Raytheon STX Corp, Lanham, MD USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. USN, Res Lab, Solar Phys Branch, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. RP Neupert, WM (reprint author), NOAA, Space Environm Ctr, Code R-E-SE,325 Broadway, Boulder, CO 80303 USA. RI Thompson, Barbara/C-9429-2012 NR 37 TC 50 Z9 52 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25215 EP 25225 DI 10.1029/2000JA004012 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300060 ER PT J AU Sterling, AC Moore, RL AF Sterling, AC Moore, RL TI Internal and external reconnection in a series of homologous solar flares SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; SOHO EIT OBSERVATIONS; MAGNETIC RECONNECTION; PLASMA EJECTION; MODEL; HOT; EVOLUTION; ERUPTIONS; TELESCOPE; MISSION AB Using data from the extreme ultraviolet imaging telescope (EIT) on SOHO and the soft X-ray telescope (SXT) on Yohkoh, we examine a series of morphologically homologous solar flares occurring in National Oceanic and Atmospheric Administration (NOAA) active region 8210 over May 1-2, 1998. An emerging flux region (EFR) impacted against a sunspot to the west and next to a coronal hole to the east is the source of the repeated flaring. An SXT sigmoid parallels the EFR's neutral line at the site of the initial flaring in soft X rays. In EIT each flaring episode begins with the formation of a crinkle pattern external to the EFR. These EIT crinkles move out from, and then in toward, the EFR with velocities similar to 20 km s(-1). A shrinking and expansion of the width of the coronal hole coincides with the crinkle activity, and generation and evolution of a postflare loop system begins near the time of crinkle formation. Using a schematic based on magnetograms of the region, we suggest that these observations are consistent with the standard reconnection-based model for solar eruptions but are modified by the presence of the additional magnetic fields of the sunspot and coronal hole. In the schematic, internal reconnection begins inside of the EFR-associated fields, unleashing a flare, postflare loops, and a coronal mass ejection (CME). External reconnection, first occurring between the escaping CME and the coronal hole field and second occurring between fields formed as a result of the first external reconnection, results in the EIT crinkles and changes in the coronal hole boundary. By the end of the second external reconnection, the initial setup is reinstated; thus the sequence can repeat, resulting in morphologically homologous eruptions. Our inferred magnetic topology is similar to that suggested in the "breakout model" of eruptions [Antiochos, 1998], although we cannot determine if our eruptions are released primarily by the breakout mechanism (external reconnection) or, alternatively, primarily by the internal reconnection. C1 George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. RP Sterling, AC (reprint author), George C Marshall Space Flight Ctr, Dept Space Sci, SD50, Huntsville, AL 35812 USA. NR 40 TC 38 Z9 38 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25227 EP 25238 DI 10.1029/2000JA004001 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300061 ER PT J AU Gopalswamy, N Lara, A Kaiser, ML Bougeret, JL AF Gopalswamy, N Lara, A Kaiser, ML Bougeret, JL TI Near-Sun and near-Earth manifestations of solar eruptions SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; II RADIO EMISSIONS; INTERPLANETARY SHOCKS; MAGNETIC CLOUDS; WIND SPACECRAFT; LASCO OBSERVATIONS; ELECTRON-DENSITY; TRANSIENT WAVES; 1 AU; BURSTS AB We compare the near-Sun and near-Earth manifestations of solar eruptions that occurred during November 1994 to June 1998. We compared white-light coronal mass ejections, metric type II radio bursts, and extreme ultraviolet wave transients (near the Sun) with interplanetary (IP) signatures such as decameter-hectometric type II bursts, kilometric type II bursts, IP ejecta, and IP shocks. We did a two-way correlation study to (1) look for counterparts of metric type II bursts that occurred close to the central meridian and (2) look for solar counterparts of IP shocks and IP ejecta. We used data from Wind and Solar and Heliospheric Observatory missions along with metric radio burst data from ground-based solar observatories. Analysis shows that (1) most (93%) of the metric type II bursts did not have IP signatures, (2) most (80%) of the IP events (IP ejecta and shocks) did not have metric counterparts, and (3) a significant fraction (26%) of IP shocks were detected in situ without drivers. In all these cases the drivers (the coronal mass ejections) were ejected transverse to the Sun-Earth line, suggesting that the shocks have a much larger extent than the drivers. Shocks originating from both limbs of the Sun arrived at Earth, contradicting earlier claims that shocks from the west limb do not reach Earth. These shocks also had good type II radio burst association. We provide an explanation for the observed relation between metric, decameter-hectometric, and kilometric type II bursts based on the fast mode magnetosonic speed profile in the solar atmosphere. C1 Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City, DF, Mexico. Univ Paris, Dept Rech Spatiale, Meudon, France. RP Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. EM gopals@fugee.gsfc.nasa.gov RI Gopalswamy, Nat/D-3659-2012; OI Lara, Alejandro/0000-0001-6336-5291 NR 49 TC 142 Z9 142 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25261 EP 25277 DI 10.1029/2000JA004025 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300064 ER PT J AU Reiner, MJ Kaiser, ML Gopalswamy, N Aurass, H Mann, G Vourlidas, A Maksimovic, M AF Reiner, MJ Kaiser, ML Gopalswamy, N Aurass, H Mann, G Vourlidas, A Maksimovic, M TI Statistical analysis of coronal shock dynamics implied by radio and white-light observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MASS EJECTIONS; SOLAR CORONA; II BURSTS; INTERPLANETARY SHOCKS; LASCO OBSERVATIONS; ELECTRON-DENSITY; WIND SPACECRAFT; WAVE; TRANSIENT; EMISSIONS AB For 19 solar eruptive events we present a statistical comparison of the shock dynamics derived from the measured frequency drift rates of metric and decametric-hectometric (D-H) type II radio bursts with the dynamics of the associated coronal mass ejection (CME). We find that the shock speed parameters derived from the D-H type II radio emissions generated in the high corona (similar to2-4 R-circle dot; R-circle dot = 696,000 km) are well correlated with the corresponding CME plane-of-the-sky speeds (correlation coefficient = 0.71). On the other hand, we find no obvious correlation between the shock speed parameters derived from the metric type II radio bursts, generated in the middle corona (1.4-2 R-circle dot), and the corresponding CME speeds (correlation coefficient = -0.07). In general, we also find no clear correlation between the shock speed parameters derived from the metric type II bursts and the D-H radio emissions (correlation coefficient = 0.3). However, the metric type II radio bursts sometimes include a second component that is possibly related to the DH radio emissions. These statistical comparisons of the shock dynamics, implied by the observed metric and D-H type II frequency drift rates, provide further evidence for two distinct coronal shocks. Our statistical analyses are preceded by two specific examples that illustrate the methodology used in this study. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Astrophys Inst Potsdam, D-14482 Potsdam, Germany. Observ Paris, Meudon, France. George Mason Univ, Inst Computat Sci, Fairfax, VA 22030 USA. Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. RP Reiner, MJ (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Vourlidas, Angelos/C-8231-2009; Gopalswamy, Nat/D-3659-2012 OI Vourlidas, Angelos/0000-0002-8164-5948; NR 60 TC 40 Z9 41 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25279 EP 25289 DI 10.1029/2000JA004024 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300065 ER PT J AU Thejappa, G MacDowall, RJ AF Thejappa, G MacDowall, RJ TI Fragmented structure of interplanetary type II bursts SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTION; EARTHS BOW SHOCK; RADIO EMISSIONS; ULYSSES OBSERVATIONS; ECLIPTIC-PLANE; ELECTRONS; DRIVEN AB We present the Ulysses observations of a highly fragmented interplanetary type II burst and an associated pair of forward shocks. We argue that the coupling of Langmuir waves excited by one of these shocks with escaping radiation at the sharp density gradient associated with the companion shock is responsible for the clumpiness of the type II event. This linear coupling process is shown to cause large fluctuations in the efficiency of conversion of Langmuir waves into elect romagnetic radiation at the fundamental of the electron plasma frequency f(pe), leading to the fragmentary structure of the type II radio burst. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Thejappa, G (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RI MacDowall, Robert/D-2773-2012 NR 24 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25313 EP 25322 DI 10.1029/2000JA004023 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300068 ER PT J AU Fairfield, DH Cairns, IH Desch, MD Szabo, A Lazarus, AJ Aellig, MR AF Fairfield, DH Cairns, IH Desch, MD Szabo, A Lazarus, AJ Aellig, MR TI The location of low Mach number bow shocks at Earth SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD ORIENTATION; SOLAR-WIND CONTROL; STANDOFF DISTANCE; MHD THEORY; MAGNETOPAUSE; SHAPE; MAGNETOSHEATH; MODEL; VENUS AB On April 26 and 27 and May 10-12, 1999, unusually low solar wind densities produced unusually low Alfven Mach numbers that moved the Earth's bow shock far out past its normal location. The shocks observed by the Wind spacecraft corresponded to shock subsolar distances of 45 and 42 R-E, respectively, on these days which are the most distant locations at which the shock has ever been seen. Shock observations by three other spacecraft on these days along with 34 previously reported distant shocks are used to compare with the predictions of different models. A recent MHD bow shock model of Cairns and Lyon [1995] predicts the observed locations quite well as does a modified gasdynamic model of Farris and Russell [1994] if a new Mach-number-dependent shape parameter is used. A third model of Verigin et al. [1997] also predicts a shock shape and is also quite good. Bow shock predictions are limited by uncertainties in measurements of the very low densities and uncertainties in the position and shape of the magnetopause. Asymmetries in the shock shape caused by the interplanetary magnetic field direction and not accounted for by models are another likely source of uncertainty. These uncertainties make it impossible to clearly favor one theoretical model over another. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Sydney, Sch Phys, Sydney, NSW 2006, Australia. MIT, Ctr Space Res, Cambridge, MA 02139 USA. RP Fairfield, DH (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. OI Cairns, Iver/0000-0001-6978-9765 NR 32 TC 37 Z9 37 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25361 EP 25376 DI 10.1029/2000JA000252 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300072 ER PT J AU Su, YH Ergun, RE Peterson, WK Onsager, TG Pfaff, R Carlson, CW Strangeway, RJ AF Su, YH Ergun, RE Peterson, WK Onsager, TG Pfaff, R Carlson, CW Strangeway, RJ TI Fast Auroral Snapshot observations of cusp electron and ion structures SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LOW-ALTITUDE OBSERVATIONS; FLUX-TRANSFER EVENTS; MAGNETOPAUSE RECONNECTION; DAYSIDE MAGNETOPAUSE; FIELD; PRECIPITATION; SIGNATURES; ACCELERATION; BOUNDARY; REGIONS AB The high time resolution observations by the Fast Auroral Snapshot satellite resolve burst-like electrons and nonmonotonic ion dispersion in the cusp region. Electric field data from a dawn-dusk cusp crossing show that the DC electric field has small-scale variations superimposed on a large-scale pattern. The large-scale DC electric field variations are well correlated with the large-scale perturbation magnetic field, indicating a field-aligned current system that reflects a relatively homogenous conductivity. Ion structures best correlate with the perturbed magnetic field and the large-scale electric field. The burst-like precipitating electrons are correlated with the small-scale electric field variations, which are most easily explained as propagating Alfven waves. We also found that the observed ion structures result from the spacecraft crossing the flow streamlines, each of which has its own individual history of dayside reconnection. The magnetosheath ion structures therefore contain information of both the spatial and temporal variations of dayside reconnection. C1 Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. NOAA, Space Environm Lab, Boulder, CO 80303 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. RP Su, YH (reprint author), Univ Colorado, Atmospher & Space Phys Lab, 1234 Innovat Dr, Boulder, CO 80303 USA. RI Pfaff, Robert/F-5703-2012; Peterson, WK/A-8706-2009 OI Pfaff, Robert/0000-0002-4881-9715; Peterson, WK/0000-0002-1513-6096 NR 28 TC 21 Z9 21 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25595 EP 25600 DI 10.1029/2001JA000093 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300087 ER PT J AU Israelevich, PL Ershkovich, AI Tsyganenko, NA AF Israelevich, PL Ershkovich, AI Tsyganenko, NA TI Magnetic field and electric current density distribution in the geomagnetic tail, based on Geotail data SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ALIGNED CURRENTS AB Analysis of Geotail magnetic data enables us to reveal the antisunward electric current flowing along the tail axis. To our knowledge, observation of this current has not been reported yet. Distributions of the magnetic field and electric current density (along with their dependencies on the tilt angle of the Earth's dipole and components of the interplanetary magnetic field) have been derived directly from Geotail data, without any ad hoc assumptions. Analysis of the electric current density distribution shows that, in addition to currents associated with the geomagnetic tail flaring, there is a current (tentatively identified as the Hall current) flowing antisunward along the tail axis. The total strength of this current is of the order of 1 MA. It closes through the midnight sector of the auroral zone resulting in field-aligned currents in the region of the Harang discontinuity. C1 Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Dept Geophys & Planetary Sci, IL-69978 Tel Aviv, Israel. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Raytheon ITSS Corp, Lanham, MD USA. RP Israelevich, PL (reprint author), Tel Aviv Univ, Raymond & Beverly Sackler Fac Exact Sci, Dept Geophys & Planetary Sci, IL-69978 Tel Aviv, Israel. RI Tsyganenko, Nikolai/J-7377-2012 OI Tsyganenko, Nikolai/0000-0002-5938-1579 NR 10 TC 5 Z9 5 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 25919 EP 25927 DI 10.1029/2000JA900165 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300111 ER PT J AU Ostgaard, N Stadsnes, J Bjordal, J Germany, GA Vondrak, RR Parks, GK Cummer, SA Chenette, DL Pronko, JG AF Ostgaard, N Stadsnes, J Bjordal, J Germany, GA Vondrak, RR Parks, GK Cummer, SA Chenette, DL Pronko, JG TI Auroral electron distributions derived from combined UV and X-ray emissions SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ULTRAVIOLET IMAGER; BREMSSTRAHLUNG; ATMOSPHERE; PRECIPITATION AB The Polar Ionospheric X-ray Imaging Experiment and the Ultraviolet Imager on board the Polar satellite provide the first simultaneous global scale views of the electron precipitation over a wide range of electron energies. By combining the results from these two remote sensing techniques we have developed a method to derive the electron energy distributions that reproduce the true electron spectra from I to 100 keV and that call be used to calculate the energy flux in the energy range from 100 eV to 100 keV. The electron energy spectra obtained by remote sensing techniques in three 5-min time intervals on July 9 and July 31, 1997, are compared with the spectra measured by low-altitude satellites in the conjugate hemisphere. In the energy range from 90 eV to 30 keV the derived energy flux is found to be 1.03 +/- 0.6 of the measured energy fluxes. The method enables us to present 5-min time-averaged global maps of precipitating electron energy fluxes with a spatial resolution of similar to 700 km. The study shows that the combination of UV and X-ray cameras oil a polar orbiting spacecraft enables comprehensive monitoring of the global energy deposition from precipitating electrons over the energy range that is most important for magnetosphere-ionosphere coupling. C1 Univ Oslo, Dept Phys, Oslo, Norway. Univ Bergen, Dept Phys, N-5007 Bergen, Norway. Univ Alabama, Ctr Space Plasma Aeron & Astrophys Res, Huntsville, AL 35899 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Washington, Geophys Program, Seattle, WA 98195 USA. Duke Univ, Dept Elect & Comp Engn, Durham, NC 27708 USA. Lockheed Martin Adv Technol Ctr, Solar & Astrophys Lab Org L9 41, Palo Alto, CA 94304 USA. Univ Nevada, Dept Phys, Reno, NV 89557 USA. RP Ostgaard, N (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Code 690,Bldg 2, Greenbelt, MD 20771 USA. RI Cummer, Steven/A-6118-2008 OI Cummer, Steven/0000-0002-0002-0613 NR 27 TC 28 Z9 28 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 26081 EP 26089 DI 10.1029/2001JA000031 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300122 ER PT J AU Geissler, PE Smyth, WH McEwen, AS Ip, W Belton, MJS Johnson, TV Ingersoll, AP Rages, K Hubbard, W Dessler, AJ AF Geissler, PE Smyth, WH McEwen, AS Ip, W Belton, MJS Johnson, TV Ingersoll, AP Rages, K Hubbard, W Dessler, AJ TI Morphology and time variability of Io's visible aurora SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA TORUS; ELECTRON-IMPACT; GALILEO; ULTRAVIOLET; SPECTROSCOPY; ATMOSPHERE; EMISSIONS; VOLCANISM; ECLIPSE; SO2 AB Clear-filter imaging of lo during the Galileo nominal and extended missions recorded diffuse auroral emissions in 16 distinct observations taken during 14 separate eclipses over a two year period. These images show that the morphology and time variability of the visible aurora have several similarities to lo's far ultraviolet emissions. The orbital leading hemisphere of lo is consistently brighter than the trailing hemisphere, probably due to a greater concentration of torus electrons in the wake region of the satellite. The locations of the polar limb glow and the bright equatorial glows appear to correlate with Io's System III longitude. Unlike the far ultraviolet emissions, the visible aurorae are enhanced near actively venting volcanic plumes, probably because of molecular emission by SO2. C1 Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. Natl Cent Univ, Inst Astron, Chungli 320, Taiwan. Belton Space Explorat Initiat, Tucson, AZ 85716 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Space Phys Res Inst, Sunnyvale, CA 94085 USA. RP Geissler, PE (reprint author), Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NR 33 TC 27 Z9 27 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 26137 EP 26146 DI 10.1029/2000JA002511 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300128 ER PT J AU Oliversen, RJ Scherb, F Smyth, WH Freed, ME Woodward, RC Marconi, ML Retherford, KD Lupie, OL Morgenthaler, JP AF Oliversen, RJ Scherb, F Smyth, WH Freed, ME Woodward, RC Marconi, ML Retherford, KD Lupie, OL Morgenthaler, JP TI Sunlit Io atmospheric [O I] 6300 angstrom emission and the plasma torus SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SYSTEM-III; LO TORUS; MODEL; SPECTROSCOPY; IONOSPHERE; ASYMMETRY; VOYAGER; JUPITER AB A large database of sunlit Io [O I] 6300 Angstrom emission, acquired over the period 1990-1999, with extensive coverage of Io orbital phase angle phi and System III longitude lambda (III), exhibits significant long-term and short-term variations in [O I] 6300 Angstrom emission intensities. The long-term average intensity shows a clear dependence on XIII, which establishes conclusively that the emission is produced by the interaction between lo's atmosphere and the plasma torus. Two prominent average intensity maxima, 70 degrees to 90 degrees wide, are centered at lambda (III) approximate to 130 degrees and lambda (III) approximate to 295 degrees. A comparison of data from October 1998 with a three-dimensional plasma torus model, based upon electron impact excitation of atomic oxygen, suggests a basis for studs of the torus interaction with Io's atmosphere. The observed shortterm, erratic [O I] 6300 Angstrom intensity variations fluctuate similar to 20-50% on a timescale of tens of minutes with less frequent fluctuations of a factor of similar to2. The most likely candidate to produce these fluctuations is a time-variable energy flux of field-aligned nonthermal electrons identified recently in Galileo plasma science data. If true, the short-term [O I] intensity fluctuations may be related to variable field-aligned currents driven by inward and outward torus plasma transport and/or transient high-latitude, field-aligned potential drops. A correlation between the intensity and emission line width indicates molecular dissociation may contribute significantly to the [O I] 6300 Angstrom emission. The nonthermal electron energy flux may produce O(D-1) by electron impact dissociation Of SO2 and SO, with the excess energy going into excitation of O and its kinetic energy. The [O I] 6300 Angstrom emission database establishes lo as a valuable probe of the torus, responding to local conditions at lo's position. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Solar Observ, Kitt Peak, AZ USA. Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. Atmospher & Environm Res Inc, Lexington, MA 02421 USA. Raytheon ITSS, Lanham, MD USA. Fresh Pond Res Inst, Cambridge, MA 02410 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Comp Sci Corp, Space Telescope Sci Inst, Baltimore, MD USA. RP Oliversen, RJ (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 33 TC 24 Z9 24 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 26183 EP 26193 DI 10.1029/2000JA002507 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300131 ER PT J AU Gurnett, DA Persoon, AM Kurth, WS Roux, A Bolton, SJ AF Gurnett, DA Persoon, AM Kurth, WS Roux, A Bolton, SJ TI Electron densities near Io from Galileo plasma wave observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID UPPER HYBRID-RESONANCE; TORUS; MAGNETOSPHERE; FREQUENCY; RADIATION; JUPITER AB This paper presents an overview of electron densities obtained near lo from the Galileo plasma wave instrument during the first four flybys of lo. These flybys were IO, which was a downstream wake pass that occurred on December 7, 1995; 124, which was an upstream pass that occurred on October 11, 1999; 125, which was a south polar pass that occurred on November 26, 1999; and 127, which was an upstream pass that occurred on February 22, 2000. Two methods were used to measure the electron density. The first was based on the frequency of upper hybrid resonance emissions, and the second was based on the low-frequency cutoff of electromagnetic radiation at the electron plasma frequency. For three of the flybys, 10, 125, and 127, large density enhancements were observed near the closest approach to lo, The peak electron densities ranged from 2.1 to 6.8 X 10(4) cm(-3). These densities are consistent with previous radio occultation measurements of To's ionosphere. No density enhancement was observed during the 124 flyby, most likely because the spacecraft trajectory passed too far upstream to penetrate lo's ionosphere. During two of the flybys, 125 and 127, abrupt step-like changes were observed at the outer boundaries of the region of enhanced electron density. Comparisons with magnetic field models and energetic particle measurements show that the abrupt density Steps occur as the spacecraft penetrated the boundary of the lo flux tube, with the region of high plasma density on the inside of the flux tube. Most likely the enhanced electron density within the lo flux tube is associated with magnetic field lines that are frozen to lo by the high conductivity of lo's atmosphere, thereby enhancing the escape of plasma along the magnetic field lines that pass through lo's ionosphere. C1 Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. UVSQ, Ctr Etud Environm Terr & Planetaires, Velizy Villacoublay, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gurnett, DA (reprint author), Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. OI Kurth, William/0000-0002-5471-6202 NR 33 TC 15 Z9 15 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2001 VL 106 IS A11 BP 26225 EP 26232 DI 10.1029/2000JA002509 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 490JT UT WOS:000172049300134 ER PT J AU Nah, RS Vadali, SR Braden, E AF Nah, RS Vadali, SR Braden, E TI Fuel-optimal, low-thrust, three-dimensional Earth-Mars trajectories SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID INTERPLANETARY TRAJECTORIES; MOON TRAJECTORIES; OPTIMIZATION AB Fuel-optimal three-dimensional trajectories from Earth to Mars for spacecraft powered by a low-thrust rocket with variable specific impulse capability are presented. The problem formulation treats the spacecraft mass as a state variable, thus coupling the spacecraft design to the trajectory optimization. Gravitational effects of the sun, Earth, and Mars are included throughout an entire trajectory. To avoid numerical sensitivity, the trajectory is divided into segments, each defined with respect to a different central body. These segments are patched at intermediate time points, with proper matching conditions on the states and costates. The optimization problem is solved using an indirect multiple shooting method. Details of trajectories for the outbound legs of crewed missions to Mars, with trip times of 145 and 168 days, are shown. Effects due to variations in the trip time, departure and arrival orbit inclinations, initial fuel mass, and power level are investigated. C1 Texas A&M Univ, Dept Aerosp Engn, College Stn, TX 77843 USA. NASA, Lyndon B Johnson Space Ctr, EG5 Adv Mission Design, Houston, TX 77058 USA. RP Nah, RS (reprint author), Texas A&M Univ, Dept Aerosp Engn, College Stn, TX 77843 USA. NR 15 TC 31 Z9 37 U1 1 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 2001 VL 24 IS 6 BP 1100 EP 1107 DI 10.2514/2.4844 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 493LH UT WOS:000172223900004 ER PT J AU Tucker, DS Ethridge, EC AF Tucker, DS Ethridge, EC TI Explanation of the effects of gravity on crystallization of ZrF2-BaF2-LaF3-AlF3-NaF glass SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID NUCLEATION; MELTS; FLOW AB The effects of gravity on crystallization of ZrF2-BaF2-LaF3-AlF3-NaF glasses have been studied by utilizing NASA's KC135 aircraft and a sounding rocket. Fibers were heated to the crystallization temperature in unit and reduced gravity. The fibers processed in unit gravity exhibited crystallization, while fibers processed in reduced gravity showed no signs of crystallization. An explanation based on shear thinning of liquids is presented to explain these results. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Tucker, DS (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 23 TC 5 Z9 5 U1 0 U2 1 PU MATERIALS RESEARCH SOCIETY PI WARRENDALE PA 506 KEYSTONE DR, WARRENDALE, PA 15086 USA SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD NOV PY 2001 VL 16 IS 11 BP 3027 EP 3029 DI 10.1557/JMR.2001.0415 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA 489YL UT WOS:000172020600002 ER PT J AU Chackerian, C Freedman, R Giver, LP Brown, LR AF Chackerian, C Freedman, R Giver, LP Brown, LR TI Absolute rovibrational intensities and self-broadening and self-shift coefficients for the X-1 Sigma(+) V=3 <- V=0 band of (CO)-C-12-O-16 SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID TRANSITION-MOMENT; LINE PARAMETERS; CO; STATE; J-LESS-THAN-OR-EQUAL-TO-150; OVERTONE AB The absolute rotationless transition moment squared for the X-1 Sigma (+) upsilon = 3 <-- upsilon = 0 band of CO is measured to be \R3-0\ (2) = 1.713 (-20, +33) x 10(-7) Debye(2). This value is about 8.6% smaller than the value assumed for HITRAN 2000. The measured Herman-Wallis intensity factor of this band is F = 1 + 0.01168(11) m + 0.0001065(79) m(2). The determination of self-broadening coefficients is improved with the inclusion of line narrowing; self-shifts are also reported. (C) 2001 Elsevier Science. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Atmospher Phys Branch, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Phys Res Inst, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Atmospher Phys Branch, Moffett Field, CA 94035 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chackerian, C (reprint author), NASA, Ames Res Ctr, MS 245-4, Moffett Field, CA 94035 USA. NR 25 TC 18 Z9 19 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD NOV PY 2001 VL 210 IS 1 BP 119 EP 126 DI 10.1006/jmsp.2001.8447 PG 8 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 502CT UT WOS:000172726700012 ER PT J AU Lim, JW Tung, C Yu, YH AF Lim, JW Tung, C Yu, YH TI Prediction of blade-vortex interaction airloads with higher-harmonic pitch controls using the 2GCHAS comprehensive code SO JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article AB Analytically predicted results of blade-vortex interaction (BVI) airloads, using the second-generation comprehensive helicopter analysis system (2GCHAS), are presented with the experimental results obtained from the higher-harmonic-control aeroacoustic rotor test (HART) program using a 40-percent, Mach-scaled model of the hingeless BO-105 main rotor Correlations include airloads, blade tip deflections, and tip vortex geometry. The effects on blade airload predictions are studied with higher-harmonic pitch controls (HHC). It was concluded that the blade torsional deflection and the wake system play a very important role in predicting BVI airloads. C1 NASA, Ames Res Ctr, AMCON, AMRDEC,Rotocraft Div, Moffett Field, CA 94035 USA. RP Lim, JW (reprint author), NASA, Ames Res Ctr, AMCON, AMRDEC,Rotocraft Div, Moffett Field, CA 94035 USA. NR 15 TC 6 Z9 6 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0094-9930 J9 J PRESS VESS-T ASME JI J. Press. Vessel Technol.-Trans. ASME PD NOV PY 2001 VL 123 IS 4 BP 469 EP 474 DI 10.1115/1.1401025 PG 6 WC Engineering, Mechanical SC Engineering GA 501EE UT WOS:000172669200012 ER PT J AU Mehta, UB Bowles, JV AF Mehta, UB Bowles, JV TI Two-stage-to-orbit spaceplane concept with growth potential SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A two-stage-to-orbit (TSTO) spaceplane concept developed in 1993 is revisited, and new information is provided to assist in the development of the next-generation space transportation vehicles. The design philosophy, TSTO spaceplane concept, and the design method are briefly described. A trade study between cold and hot structures leads to the choice of cold structures with external thermal protection systems. The optimal Mach number for staging the second stage of the TSTO spaceplane (with airbreathing propulsion on the first stage) is 10, based on life-cycle cost analysis. Mass properties of four TSTO spaceplanes with a turbo/ram/scramjet propulsion system on the first stage are presented, and the specification and performance of one of these spaceplanes are discussed. Two of these spaceplanes have builtin growth potential, and one of these is proposed as a prototype/experimental TSTO spaceplane to address the near-term access to space needs. The internal rate of return on investment is the highest for the proposed TSTO spaceplane, vis-A-vis a single-stage-to-orbit rocket vehicle and a TSTO spaceplane without builtin growth. Additional growth potentials for the proposed spaceplane are suggested. This spaceplane-can substantially decrease access-to-space cost and risk and increase safety and reliability in the near term. It can be a serious candidate for the next-generation space transportation system. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Syst Anal Branch, Moffett Field, CA 94035 USA. RP Mehta, UB (reprint author), NASA, Ames Res Ctr, Space Technol Div, Mail Stop 229-3, Moffett Field, CA 94035 USA. NR 19 TC 6 Z9 6 U1 1 U2 7 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 2001 VL 17 IS 6 BP 1149 EP 1161 DI 10.2514/2.5886 PG 13 WC Engineering, Aerospace SC Engineering GA 495AA UT WOS:000172317000003 ER PT J AU Engelund, WC AF Engelund, WC TI Hyper-X aerodynamics: The X-43A airframe-integrated scramjet propulsion flight-test experiments SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Engelund, WC (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 0 TC 10 Z9 12 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2001 VL 38 IS 6 BP 801 EP 802 DI 10.2514/2.3757 PG 2 WC Engineering, Aerospace SC Engineering GA 504QK UT WOS:000172867200001 ER PT J AU Engelund, WC Holland, SD Cockrell, CE Bittner, RD AF Engelund, WC Holland, SD Cockrell, CE Bittner, RD TI Aerodynamic database development for the Hyper-X airframe-integrated scramjet propulsion experiments SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 18th Applied Aerodynamics Conference CY AUG 14-17, 2000 CL DENVER, COLORADO SP Amer Inst Aeronaut & Astronaut AB An overview of the activities associated with the aerodynamic database that is being developed in support of NASA's Hyper-X scramjet flight experiments is provided. Three flight tests are planned as part of the Hyper-X program. Each will utilize a small, non-recoverable research vehicle with an airframe-integrated scramjet propulsion engine. The research vehicles will be individually rocket boosted to the scramjet engine test points at Mach 7 and 10. The research vehicles will then separate from the first stage booster vehicle and the scramjet engine test will be conducted before the terminal decent phase of the flight. An overview is provided of the activities associated with the development of the Hyper-X aerodynamic database, including wind-tunnel test activities and parallel computational fluid dynamics analysis efforts for all phases of the Hyper-X flight tests. A brief summary of the Hyper-X research vehicle aerodynamic characteristics is provided, including the direct and indirect effects of the airframe-integrated scramjet propulsion system operation on the basic airframe stability and control characteristics. Brief comments on the planned postflight data analysis efforts are also included. C1 NASA, Langley Res Ctr, Vehicle Analysis Branch, Hampton, VA 23681 USA. FDC NYMA Inc, Hyperson Numer Applicat Sect, Hyper X Program Off, Hampton, VA 23681 USA. NASA Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NASA Langley Res Ctr, Hyperson Airbreathing Prop Branch, Hampton, VA 23681 USA. RP Engelund, WC (reprint author), NASA, Langley Res Ctr, Vehicle Analysis Branch, MS 365, Hampton, VA 23681 USA. NR 21 TC 9 Z9 13 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2001 VL 38 IS 6 BP 803 EP 810 DI 10.2514/2.3768 PG 8 WC Engineering, Aerospace SC Engineering GA 504QK UT WOS:000172867200002 ER PT J AU Woods, WC Holland, SD DiFulvio, M AF Woods, WC Holland, SD DiFulvio, M TI Hyper-X stage separation wind-tunnel test program SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 18th Applied Aerodynamics Conference CY AUG 14-17, 2000 CL DENVER, COLORADO SP Amer Inst Aeronaut & Astronaut AB NASA's Hyper-X research program was developed primarily to flight demonstrate a supersonic combustion ramjet engine, fully integrated with a forebody designed to tailor inlet flow conditions and a free expansion nozzle/afterbody to produce positive thrust at design flight conditions. With a point-designed propulsion system the vehicle must depend on some other means for boost to its design flight condition. Clean separation from this initial propulsion system stage within less than a second is critical to the success of the flight. This paper discusses the early planning activity, background, and chronology that developed the series of wind-tunnel tests to support multi-degree-of-freedom simulation of the separation process. Representative results from each series of tests are presented, and issues and concerns during the process and current status are highlighted. C1 NASA Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. RP Woods, WC (reprint author), NASA Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NR 19 TC 7 Z9 8 U1 2 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2001 VL 38 IS 6 BP 811 EP 819 DI 10.2514/2.3770 PG 9 WC Engineering, Aerospace SC Engineering GA 504QK UT WOS:000172867200003 ER PT J AU Buning, PG Wong, TC Dilley, AD Pao, JL AF Buning, PG Wong, TC Dilley, AD Pao, JL TI Computational fluid dynamics prediction of Hyper-X stage separation aerodynamics SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 18th Applied Aerodynamics Conference CY AUG 14-17, 2000 CL DENVER, COLORADO SP Amer Inst Aeronaut & Astronaut AB The NASA X-43 Hyper-X hypersonic research vehicle will be boosted to a Mach 7 flight test condition mounted on the nose of a Pegasus launch vehicle. The separation of the research vehicle from the Pegasus presents some unique aerodynamic problems, for which computational fluid dynamics has played a role in the analysis. We describe the use of several computational methods for investigating the aerodynamics of the research and launch vehicles in close proximity. Specifically addressed are unsteady effects, aerodynamic database extrapolation, and differences between wind-tunnel and flight environments. C1 NASA Langley Res Ctr, Configurat Aerodynam Branch, Hampton, VA 23681 USA. FDC NYMA Inc, Hyper X Program Off, Hampton, VA 23681 USA. RP Buning, PG (reprint author), NASA Langley Res Ctr, Configurat Aerodynam Branch, Hampton, VA 23681 USA. NR 27 TC 9 Z9 11 U1 0 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2001 VL 38 IS 6 BP 820 EP 827 DI 10.2514/2.3771 PG 8 WC Engineering, Aerospace SC Engineering GA 504QK UT WOS:000172867200004 ER PT J AU Holland, SD Woods, WC Engelund, WC AF Holland, SD Woods, WC Engelund, WC TI Hyper-X research vehicle experimental aerodynamics test program overview SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 18th Applied Aerodynamics Conference CY AUG 14-17, 2000 CL DENVER, COLORADO SP Amer Inst Aeronaut & Astronaut AB An overview is provided of the experimental aerodynamics test program to ensure mission success for the autonomous flight of the Hyper-X research vehicle, a 12-ft-long, 2700-lb lifting body technology demonstrator designed to flight demonstrate for the first time a fully airframe-integrated scramjet propulsion system. Three flights are planned, two at Mach 7 and one at Mach 10. The research vehicles will be boosted to the prescribed scramjet engine test point, where they will separate from the booster, stabilize, and initiate engine test. Following more than 5 s of powered flight and 15 s of cowl-open tares, the cowl will close, and the vehicle will fly a controlled deceleration trajectory, which includes numerous control doublets for in-flight aerodynamic parameter identification. The preflight testing activities, wind-tunnel models, test rationale, risk reduction activities, and sample results from wind-tunnel tests supporting the flight trajectory from hypersonic engine test point through subsonic flight termination are reviewed. C1 NASA Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NASA Langley Res Ctr, Vehicle Analysis Branch, Hampton, VA 23681 USA. RP Holland, SD (reprint author), NASA Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NR 17 TC 10 Z9 17 U1 2 U2 9 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2001 VL 38 IS 6 BP 828 EP 835 DI 10.2514/2.3772 PG 8 WC Engineering, Aerospace SC Engineering GA 504QK UT WOS:000172867200005 ER PT J AU Cockrell, CE Engelund, WC Bittner, RD Jentink, TN Dilley, AD Frendi, A AF Cockrell, CE Engelund, WC Bittner, RD Jentink, TN Dilley, AD Frendi, A TI Integrated aeropropulsive computational fluid dynamics methodology for the Hyper-X flight experiment SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 18th Applied Aerodynamics Conference CY AUG 14-17, 2000 CL DENVER, COLORADO SP Amer Inst Aeronaut & Astronaut AB Computational fluid dynamics tools have been used extensively in the analysis and development of the X-43A Hyper-X Research Vehicle. A significant element of this analysis is the prediction of integrated vehicle aeropropulsive performance, which includes an integration of aerodynamic and propulsion flowfields. The development of the Mach 7 X-43A required a preflight assessment of longitudinal and lateral-directional aeropropulsive characteristics near the target flight-test condition. The development of this preflight database was accomplished through extensive aerodynamic wind-tunnel testing and a combination of three-dimensional inviscid airframe calculations and cowl-to-tail scramjet cycle analyses to generate longitudinal performance increments between mission sequences. These increments were measured directly and validated through tests of the Hyper-X flight engine and vehicle flowpath simulator in the NASA Langley Research Center 8-Foot High Temperature Tunnel. Predictions were refined with tip-to-tail Navier-Stokes calculations, which also provided information on scramjet exhaust plume expansion in the aftbody region. A qualitative assessment of lateral-directional stability characteristics was made through a series of tip-to-tail inviscid calculations, including a simulation of the powered scramjet flight-test condition. Additional comparisons with wind-tunnel force and moment data as well as surface pressure measurements from the Hyper-X flight engine and vehicle flowpath simulator model and wind-tunnel testing were made to assess solution accuracy. C1 NASA Langley Res Ctr, Hyperson Airbreathing Prop Branch, Hampton, VA 23681 USA. FDC NYMA Inc, Hyperson Numer Applicat Sect, Hyper X Program Off, Hampton, VA 23681 USA. Univ Alabama, Dept Mech & Aerosp Engn, Huntsville, AL 35899 USA. NASA Langley Res Ctr, Vehicle Analysis Branch, Hampton, VA 23681 USA. RP Cockrell, CE (reprint author), NASA Langley Res Ctr, Hyperson Airbreathing Prop Branch, Hampton, VA 23681 USA. NR 23 TC 15 Z9 18 U1 0 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2001 VL 38 IS 6 BP 836 EP 843 DI 10.2514/2.3773 PG 8 WC Engineering, Aerospace SC Engineering GA 504QK UT WOS:000172867200006 ER PT J AU Huebner, LD Rock, KE Ruf, EG Witte, DW Andrews, EH AF Huebner, LD Rock, KE Ruf, EG Witte, DW Andrews, EH TI Hyper-X flight engine ground testing for flight risk reduction SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 10th International Space Planes Conference CY APR 24-27, 2001 CL KYOTO, JAPAN SP Amer Inst Aeronaut & Astronaut AB Airframe-integrated scramjet engine testing has been completed at Mach 7 flight conditions in the NASA Langley 8-Foot High Temperature Tunnel as part of the NASA Hyper-X program. This test provided engine performance and operability data, as well as design and database verification, for the Mach 7 flight tests of the Hyper-X research vehicle, which will provide the first-ever airframe-integrated scramjet data in flight. The Hyper-X Flight Engine, a duplicate Mach 7 scramjet engine for flight, was mounted on an airframe structure that replicated the entire three-dimensional propulsion flowpath from the vehicle leading edge to the vehicle trailing edge. This model was also tested to verify and validate the complete flightlike engine system. The subsystems that were subjected to flightlike conditions are described, and supporting data are presented. The results from this test help to reduce risk for the Mach 7 flights of the Hyper-X research vehicle. C1 NASA Langley Res Ctr, Hyperson Airbreathing Prop Branch, Hampton, VA 23681 USA. FDC NYMA Inc, Hyper X Program Off, Hampton, VA 23681 USA. RP Huebner, LD (reprint author), NASA Langley Res Ctr, Hyperson Airbreathing Prop Branch, Hampton, VA 23681 USA. NR 8 TC 13 Z9 13 U1 1 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2001 VL 38 IS 6 BP 844 EP 852 DI 10.2514/2.3774 PG 9 WC Engineering, Aerospace SC Engineering GA 504QK UT WOS:000172867200007 ER PT J AU Berry, SA Auslender, AH Dilley, AD Calleja, JF AF Berry, SA Auslender, AH Dilley, AD Calleja, JF TI Hypersonic boundary-layer trip development for Hyper-X SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT AIAA 18th Applied Aerodynamics Conference CY AUG 14-17, 2000 CL DENVER, COLORADO SP Amer Inst Aeronaut & Astronaut ID TRANSITION AB Boundary-layer trip devices for the Hyper-X forebody have been experimentally examined in several wind tunnels. Five different trip configurations were compared in three hypersonic facilities: the NASA Langley Research Center 20-Inch Mach 6 Air and 31-Inch Mach 10 Air tunnels and in the HYPULSE Reflected Shock Tunnel at the General Applied Sciences Laboratory. Heat-transfer distributions, utilizing the phosphor thermography and thin-film techniques, shock system details, and surface streamline patterns were measured on a 0.333-scale model of the Hyper-X forebody. Parametric variations include angles of attack of 0, 2, and 4 deg; Reynolds numbers based on model length of 1.2 x 10(6)-15.4 x 10(6); and inlet cowl door simulated in both open and closed positions. Comparisons of boundary-layer transition as a result of discrete roughness elements have led to the selection of a trip configuration for the Hyper-X Mach 7 flight vehicle. C1 NASA Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. FDC NYMA Inc, Hyper X Program Off, Hampton, VA 23681 USA. Gen Appl Sci Lab Inc, Ronkonkoma, NY 11779 USA. NASA Langley Res Ctr, Hyperson Airbreathing Prop Branch, Hampton, VA 23681 USA. RP Berry, SA (reprint author), NASA Langley Res Ctr, Aerothermodynam Branch, Hampton, VA 23681 USA. NR 52 TC 38 Z9 45 U1 1 U2 11 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2001 VL 38 IS 6 BP 853 EP 864 DI 10.2514/2.3775 PG 12 WC Engineering, Aerospace SC Engineering GA 504QK UT WOS:000172867200008 ER PT J AU Eldridge, JI Zhu, DM Miller, RA AF Eldridge, JI Zhu, DM Miller, RA TI Mesoscopic nonlinear elastic modulus of thermal barrier coatings determined by cylindrical punch indentation SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID DEPOSITS; HARDNESS AB Cylindrical punch indentations are performed to determine the effective modulus of a plasma-sprayed ZrO2-8 wt% Y2O3 thermal barrier coating (TBC) as a function of coating depth. Cylindrical punch indentations offer significant advantages over pointed (Vickers, Berkovich, or Knoop) indentations for materials that do not exhibit linear elastic behavior. Cyclic loading with a cylindrical punch clearly shows the TBCs to exhibit nonlinear elastic behavior with significant hysteresis that is related to the compaction and internal sliding within the plasma-spray splat microstructure. Also, the effect of a high-heat-flux laser treatment is shown to produce a gradient both in the effective TBC modulus and degree of loading/unloading hysteresis with depth. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Eldridge, JI (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 18 TC 15 Z9 15 U1 0 U2 8 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD NOV PY 2001 VL 84 IS 11 BP 2737 EP 2739 PG 3 WC Materials Science, Ceramics SC Materials Science GA 491YE UT WOS:000172137000052 ER PT J AU Nicholson, LM Gates, TS AF Nicholson, LM Gates, TS TI The influence of cross-link density on the creep compliance of an advanced polyimide SO JOURNAL OF THERMOPLASTIC COMPOSITE MATERIALS LA English DT Article ID PHYSICAL-PROPERTIES; EPOXY-RESINS; COMPOSITES; POLYMERS AB The effect of cross-link density on the visco-elastic performance of an advanced polymer matrix (LaRC(TM) -PETI-SI) was investigated through creep compliance tests. Testing consisted of short-term isothermal creep and recovery with the creep segments performed under constant load. The tests were conducted at three temperatures below the glass transition temperature of each material with different cross-link density. Through the use of time-aging-time superposition procedures, the material constants, material master curves and aging-related parameters were evaluated at each temperature for a given cross-link density. It was shown that the high cross-link density materials have increased creep compliance and creep compliance rate, and are less sensitive to physical aging than the low cross-link density materials. The temperature sensitivity of the time-temperature superposition (TTSP) shift factor was shown to increase monotonically with increasing cross-link density. Furthermore, at the highest temperature, a separation in the TTSP shift factors was apparent between different cross-link densities. This separation occurred at a molecular weight (M-c) of similar to 3321 g/mol. C1 NASA, Mech & Durabil Branch, Langley Res Ctr, Hampton, VA 23681 USA. NASA, ICASE, Struct & Mat Div, Langley Res Ctr, Hampton, VA 23681 USA. RP Gates, TS (reprint author), NASA, Mech & Durabil Branch, Langley Res Ctr, MS 188E,2 W Reid St, Hampton, VA 23681 USA. NR 11 TC 4 Z9 4 U1 1 U2 2 PU SAGE PUBLICATIONS LTD PI LONDON PA 6 BONHILL STREET, LONDON EC2A 4PU, ENGLAND SN 0892-7057 J9 J THERMOPLAST COMPOS JI J. Thermoplast. Compos. Mater. PD NOV PY 2001 VL 14 IS 6 BP 477 EP 488 DI 10.1106/CH7V-6PML-91WG-RY50 PG 12 WC Materials Science, Composites SC Materials Science GA 500LN UT WOS:000172629200002 ER PT J AU Whitacre, JF Yalisove, SM Bilello, JC AF Whitacre, JF Yalisove, SM Bilello, JC TI Real-time/in situ diffraction study of phase and microstructural evolution in sputtered beta-Ta/Ta2O5 films SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article ID THIN; TA2O5 AB The evolution of texture, grain size, and phase content in sputtered beta -Ta/Ta2O5 films was studied and controlled in situ using a laboratory-based real-time x-ray diffraction system. The films were dc magnetron sputter deposited using sputter gas (Ar) pressures ranging from 2 to 20 mTorr. To collect diffraction data during growth, a grazing incidence x-ray scattering (GIXS) configuration was necessary. Because this configuration complicated the interpretation of texturing data, complete Schultz geometry pole figures were also used to characterize the films after growth, and the relationship between pole figure and GIXS data was examined. The film composition was evaluated using sputter profile x-ray photoelectron spectroscopy and secondary ion mass spectroscopy. It was found that the degree and rate of (002) out-of-plane texturing was systematically stronger in films grown at lower Ar pressures (< 10 mTorr). These films were predominantly beta -Ta in composition and had relatively large grains (similar to 50 nm in diameter). Films grown using progressively higher Ar pressures had increasing amounts of Ta2O5, developed a (002) out-of-plane texture more slowly, and were nanocrystalline/amorphous in nature. Data from depositions where the Ar pressure was changed during growth showed that the deposition environment at the instant of layer formation determined the phase content, degree of texture, and grain size in the developing film; the characteristics of previous layers had little bearing on subsequent growth. This shows that tailored multilayer beta -Ta/Ta2O5 films may be created and monitored in situ. (C) 2001 American Vacuum Society. C1 Univ Michigan, Dept Mat Sci & Engn, Ann Arbor, MI 48109 USA. RP Whitacre, JF (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 31 TC 5 Z9 5 U1 3 U2 4 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD NOV-DEC PY 2001 VL 19 IS 6 BP 2910 EP 2919 DI 10.1116/1.1414119 PG 10 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA 497QE UT WOS:000172466300030 ER PT J AU Del Castillo, CE Coble, PG Conmy, RN Muller-Karger, FE Vanderbloemen, L Vargo, GA AF Del Castillo, CE Coble, PG Conmy, RN Muller-Karger, FE Vanderbloemen, L Vargo, GA TI Multispectral in situ measurements of organic matter and chlorophyll fluorescence in seawater: Documenting the intrusion of the Mississippi River plume in the West Florida Shelf SO LIMNOLOGY AND OCEANOGRAPHY LA English DT Article ID ORINOCO-RIVER; OPTICAL-PROPERTIES; SEA; ABSORPTION; SPECTRA; WATERS AB We performed multispectral, in situ fluorescence measurements of detrital colored organic matter (COM) and chlorophyll a (Chi a) in surface waters of the West Florida Shelf using the Wet Labs spectral absorption and fluorescence instrument (SAFIre). Continuous underway measurements allowed simultaneous mapping of the dispersal pattern of riverine organic material and Chl a on the shelf. We used two fluorescence emission ratios to differentiate between riverine and marine COM. The data showed unusually high concentrations of COM offshore. These were attributed to an offshore extension of the Mississippi River plume. Comparisons between in situ Chl a concentrations measured with the SAFIre and Chl a values obtained from the sea-viewing wide field-of-view sensor (SeaWiFS) satellite data using OC4 and MODIS algorithms showed that, although both algorithms overestimated Chi a, MODIS performed better than OC4, particularly in areas with high COM concentrations. Analysis of the relationship between Chl a and COM concentrations within the study area showed regional variability probably caused by differences in river source. C1 NASA, Stennis Space Ctr, MS 39529 USA. Univ S Florida, Coll Marine Sci, St Petersburg, FL 33701 USA. RP Del Castillo, CE (reprint author), NASA, Code MA00 Bldg 1100 202-B, Stennis Space Ctr, MS 39529 USA. RI Del Castillo, Carlos/N-2601-2013 NR 28 TC 60 Z9 60 U1 2 U2 14 PU AMER SOC LIMNOLOGY OCEANOGRAPHY PI WACO PA 5400 BOSQUE BLVD, STE 680, WACO, TX 76710-4446 USA SN 0024-3590 J9 LIMNOL OCEANOGR JI Limnol. Oceanogr. PD NOV PY 2001 VL 46 IS 7 BP 1836 EP 1843 PG 8 WC Limnology; Oceanography SC Marine & Freshwater Biology; Oceanography GA 491VZ UT WOS:000172131900028 ER PT J AU DellaCorte, C AF DellaCorte, C TI 9/11/01 changed everything... or did it? SO LUBRICATION ENGINEERING LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Washington, DC 20546 USA. RP DellaCorte, C (reprint author), NASA, Glenn Res Ctr, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD NOV PY 2001 VL 57 IS 11 BP 3 EP 3 PG 1 WC Engineering, Mechanical SC Engineering GA 488LF UT WOS:000171936100001 ER PT J AU Goldin, DS Venneri, SL Noor, AK AF Goldin, DS Venneri, SL Noor, AK TI Fresh air, wide-open space SO MECHANICAL ENGINEERING LA English DT Article C1 NASA, Washington, DC 20546 USA. Old Dominion Univ, Norfolk, VA USA. NASA, Langley Res Ctr, Ctr Adv Engn Environm, Hampton, VA 23665 USA. Univ Florida, Gainesville, FL USA. RP Goldin, DS (reprint author), NASA, Washington, DC 20546 USA. NR 0 TC 6 Z9 6 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0025-6501 J9 MECH ENG JI Mech. Eng. PD NOV PY 2001 VL 123 IS 11 BP 48 EP 55 PG 8 WC Engineering, Mechanical SC Engineering GA 490QX UT WOS:000172063500035 ER PT J AU Draper, SL Lerch, BA Pereira, JM Nathal, MV Austin, CM Erdmann, O AF Draper, SL Lerch, BA Pereira, JM Nathal, MV Austin, CM Erdmann, O TI The effect of ballistic impacts on the high-cycle fatigue properties of Ti-48Al-2Nb-2Cr (atomic percent) SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID STRENGTH; DAMAGE AB The ability of gamma -TiAl to withstand potential foreign object damage (FOD) and/or domestic object damage (DOD) is a technical risk to the implementation of gamma -TiAl in low-pressure turbine (LPT) blade applications. The overall purpose of the present study was to determine the influence of ballistic impact damage on the high-cycle fatigue strength of gamma -TiAl-simulated LPT blades. Impact and specimen variables included ballistic impact energy, projectile hardness, impact temperature, impact location, and leading-edge thickness. The level of damage induced by the ballistic impacting was studied and quantified on both the impact (front) and backside of the specimens. Multiple linear regression was used to model the cracking and fatigue response as a function of the impact variables. Of the impact variables studied, impact energy, had the largest influence on the response of gamma -TiAl to ballistic impacting. Backside crack length (BSCL) was the best predictor of remnant fatigue strength for low-energy impacts (<0.74 J), whereas, Hertzian crack length (HCL) (impact side damage) was the best predictor for higher-energy impacts. The impacted gamma -TiAl samples displayed a classical mean stress dependence on the fatigue strength. For the fatigue design stresses of a sixth-stage LPT blade in a GE90 engine, a Ti-48Al-2Nb-2Cr LPT blade would survive an impact of normal service conditions. C1 NASA, Glenn Res Ctr Lewis Field, Div Mat, Adv Met Branch, Cleveland, OH 44135 USA. NASA, Glenn Res Ctr Lewis Field, Struct & Acoust Div, Cleveland, OH 44135 USA. GE Aircraft Engines, Cincinnati, OH 45215 USA. RP Draper, SL (reprint author), NASA, Glenn Res Ctr Lewis Field, Div Mat, Adv Met Branch, Cleveland, OH 44135 USA. NR 13 TC 10 Z9 10 U1 1 U2 3 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 184 THORN HILL RD, WARRENDALE, PA 15086 USA SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD NOV PY 2001 VL 32 IS 11 BP 2743 EP 2758 DI 10.1007/s11661-001-1026-5 PG 16 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA 491LQ UT WOS:000172110200007 ER PT J AU Pawlowski, JF Hebert, TJ Hawkes, RL Matney, MJ Stansbery, EG AF Pawlowski, JF Hebert, TJ Hawkes, RL Matney, MJ Stansbery, EG TI Flux of very faint Leonid meteors observed with a 3 meter liquid mirror telescope intensified charge-coupled device system SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID STORMS; DANGER AB We have used a 3.0 m diameter liquid mirror telescope (LMT) coupled to a microchannel plate image-intensified charge-coupled device (CCD) detector to study the 1999 Leonid meteor shower. This is the largest aperture optical instrument ever utilized for meteor detection. While the observing system is sensitive down to stars of +18 astronomical magnitude under optimum conditions, when corrections for meteor motion are applied the majority of the meteors collected fall in the absolute magnitude range from +5 to +10, corresponding to photometric masses from about 10(-7) to 10(-9) kg. This is largely due to the fact that the field of view of the LMT was only 0.28 degrees, so that only a small portion of the luminous meteor trail was recorded. While the flux of these small (1.4 x 10-9 kg) Leonid meteors is low (on the order of one Leonid meteor per hour per square kilometer perpendicular to the Leonid), we do have clear evidence that the Leonid stream contains particles in the mass range studied here. The data showed a possibly significant peak in Leonid flux (9.3 +/- 3.5) for the 1 h period from 11:00 to 12:00 U.T. 1999 November 17 (solar longitude 234.653 to 234.695, epoch 2000.0), although the main trend of these results is a broad low-level Leonid activity. There is evidence that small meteoroids are more widely distributed in the Leonid stream, as would be expected from cometary ejection stream models. As would be expected from an extrapolation of mass distribution indices for brighter meteors, the vast majority of meteors at this size are sporadic. The LMT is a powerful detector of sporadic meteors, with an average non-Leonid detection rate of more than 140 meteor events per hour. C1 Mt Allison Univ, Dept Phys, Sackville, NB E4L 1E6, Canada. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Houston, Dept Elect & Comp Engn, Houston, TX 77204 USA. NASA, Lyndon B Johnson Space Ctr, Lockheed Martin Engn & Sci Serv, Houston, TX 77058 USA. RP Pawlowski, JF (reprint author), Mt Allison Univ, Dept Phys, 67 York St, Sackville, NB E4L 1E6, Canada. NR 38 TC 8 Z9 9 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD NOV PY 2001 VL 36 IS 11 BP 1467 EP 1477 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 502HA UT WOS:000172736900005 ER PT J AU Vandooren, A Conley, JF Cristoloveanu, S Mojarradi, M Kolawa, E AF Vandooren, A Conley, JF Cristoloveanu, S Mojarradi, M Kolawa, E TI Degradation mechanisms in SOI n-channel LDMOSFETs SO MICROELECTRONIC ENGINEERING LA English DT Article; Proceedings Paper CT 12th Biennial Conference on Insulating Films on Semiconductors CY JUN 20-23, 2001 CL UDINE, ITALY SP ST Microelectr, IEEE Electron Device Soc, NEAR EST Consortium, CISM, Regione Friuli Venezia Giulia, Undine, Fdn CRUP DE LDMOSFET; SOI; irradiation; hot-carrier degradation; low temperature; high-voltage AB The back-gate bias modifies the series resistance and the overall performance of LDMOSFETs in linear and saturation operation. The influence of the back-gate under degradation conditions is investigated. Degradations due to irradiation, hot carrier injection, and low temperature are complex and differ from the case of low-voltage CMOS transistors. The degradation mechanisms are clearly identified and the main parameters are extracted using the model of the LDMOS in linear operation. (C) 2001 Elsevier Science B.V. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. ENSERG, LPCS, URA CNRS & INPG, F-38016 Grenoble 1, France. RP Vandooren, A (reprint author), Motorola Inc, Digital DNA Labs, 3501 Ed Bluestein Blvd,MD-K20, Austin, TX 78721 USA. NR 4 TC 1 Z9 1 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-9317 J9 MICROELECTRON ENG JI Microelectron. Eng. PD NOV PY 2001 VL 59 IS 1-4 BP 489 EP 495 DI 10.1016/S0167-9317(01)00663-3 PG 7 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Optics; Physics, Applied SC Engineering; Science & Technology - Other Topics; Optics; Physics GA 493JD UT WOS:000172218100071 ER PT J AU Jordan, JA Fraga, DN Lupo, PJ Gonda, SR AF Jordan, JA Fraga, DN Lupo, PJ Gonda, SR TI A three-dimensional transgenic model for mutational analysis: Vimentin and cytokeratin protein expression SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 Univ Space Res Assoc, Div Space & Life Sci, Houston, TX 77058 USA. Univ Notre Dame, Notre Dame, IN 46556 USA. NASA, Lyndon B Johnson Space Ctr, Cellular Biotechnol Program, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC CELL BIOLOGY PI BETHESDA PA 8120 WOODMONT AVE, STE 750, BETHESDA, MD 20814-2755 USA SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD NOV PY 2001 VL 12 SU S MA 296 BP 54A EP 54A PG 1 WC Cell Biology SC Cell Biology GA 496AL UT WOS:000172372500297 ER PT J AU Whitson, PA Pietrzyk, RA Morukov, BV Sams, CF AF Whitson, PA Pietrzyk, RA Morukov, BV Sams, CF TI The risk of renal stone formation during and after long duration space flight SO NEPHRON LA English DT Article DE renal stone; space flight; aerospace medicine ID ABSORPTION; CALCIUM; CITRATE; ALKALI AB Background. The formation of a renal stone during space flight may have serious negative effects on the health of the crewmember and the success of the mission. Urinary biochemical factors and the influence of dietary factors associated with renal stone development were assessed during long duration Mir Space Station missions. Methods: Twenty-four-hour urine samples were collected prior to, during and following long duration space flight. The relative urinary supersaturation of calcium oxalate, calcium phosphate (brushite), sodium urate, struvite and uric acid were determined. Results: Changes in the urinary biochemistry of crewmembers during long duration spaceflight demonstrated increases in the supersaturation of the stone-forming salts. In-flight hypercalciuria was evident in a number of individual crewmembers and 24-hour dietary fluid intake and urine volume were significantly lower. During flight, there was a significant increase in brushite supersaturation. Conclusions: These data suggest acute effects of space flight and postflight changes in the urinary biochemistry favoring increased crystallization in the urine. The effects of dietary intake, especially fluid intake, may have a significant impact on the potential for renal stone formation. Efforts are now underway to assess the efficacy of a countermeasure to mitigate the increased risk. Copyright (C) 2001 S. Karger AG, Basel. C1 NASA, Lyndon B Johnson Space Ctr, Astronaut Off, Houston, TX 77058 USA. Wyle Life Sci, Houston, TX USA. Inst Biomed Problems, Moscow, Russia. RP Whitson, PA (reprint author), NASA, Lyndon B Johnson Space Ctr, Astronaut Off, Mail Code CB, Houston, TX 77058 USA. NR 21 TC 40 Z9 41 U1 0 U2 0 PU KARGER PI BASEL PA ALLSCHWILERSTRASSE 10, CH-4009 BASEL, SWITZERLAND SN 0028-2766 J9 NEPHRON JI Nephron PD NOV PY 2001 VL 89 IS 3 BP 264 EP 270 DI 10.1159/000046083 PG 7 WC Urology & Nephrology SC Urology & Nephrology GA 484ZX UT WOS:000171728000004 PM 11598387 ER PT J AU Talukder, A Casasent, D AF Talukder, A Casasent, D TI A closed-form neural network for discriminatory feature extraction from high-dimensional data SO NEURAL NETWORKS LA English DT Article DE dimensionality reduction; discrimination; feature extraction (nonlinear); neural networks; nonlinear transform; pattern recognition ID PRINCIPAL COMPONENT ANALYSIS; NONLINEAR PCA; REPRESENTATION; CLASSIFICATION AB We consider a new neural network for data discrimination in pattern recognition applications. We refer to this as a maximum discriminating feature (MDF) neural network. Its weights are obtained in closed-form, thereby overcoming problems associated with other nonlinear neural networks. It uses neuron activation functions that are dynamically chosen based on the application. It is theoretically shown to provide nonlinear transforms of the input data that are more general than those provided by other nonlinear multilayer perceptron neural network and support-vector machine techniques for cases involving high-dimensional (image) inputs where training data are limited and the classes are not linearly separable. We experimentally verify this on synthetic examples. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Carnegie Mellon Univ, Dept Elect & Comp Engn, Pittsburgh, PA 15213 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Casasent, D (reprint author), Carnegie Mellon Univ, Dept Elect & Comp Engn, Pittsburgh, PA 15213 USA. NR 38 TC 11 Z9 11 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0893-6080 J9 NEURAL NETWORKS JI Neural Netw. PD NOV PY 2001 VL 14 IS 9 BP 1201 EP 1218 DI 10.1016/S0893-6080(01)00103-4 PG 18 WC Computer Science, Artificial Intelligence SC Computer Science GA 488AA UT WOS:000171910800007 PM 11718421 ER PT J AU Tippett, MK Cohn, SE AF Tippett, MK Cohn, SE TI Adjoints and low-rank covariance representation SO NONLINEAR PROCESSES IN GEOPHYSICS LA English DT Article; Proceedings Paper CT EGS 25th General Assembly on Quantifying Predictability CY APR, 2000 CL NICE, FRANCE SP Nonlinear Processes Geophys Sect, Oceans & Atmosphere Sect ID DATA ASSIMILATION; SINGULAR VECTORS; LYAPUNOV EQUATION; ERROR COVARIANCE; KALMAN FILTER; OPERATORS; PREDICTION; SYSTEMS AB Quantitative measures of the uncertainty of Earth system estimates can be as important as the estimates themselves. Direct calculation of second moments of estimation errors, as described by the covariance matrix, is impractical when the number of degrees of freedom of the system state is large and the sources of uncertainty are not completely known. Theoretical analysis of covariance equations can help guide the formulation of low-rank covariance approximations, such as those used in ensemble and reduced-state approaches for prediction and data assimilation. We use the singular value decomposition and recently developed positive map techniques to analyze a family of covariance equations that includes stochastically forced linear systems. We obtain covariance estimates given imperfect knowledge of the sources of uncertainty and we obtain necessary conditions for low-rank approximations to be appropriate. The results are illustrated in a stochastically forced system with time-invariant linear dynamics. C1 LDEO, Int Res Inst Climate Predict, Palisades, NY USA. NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Tippett, MK (reprint author), LDEO, Int Res Inst Climate Predict, Palisades, NY USA. RI Tippett, Michael/C-6286-2011; Cohn, Stephen/K-1954-2012 OI Tippett, Michael/0000-0002-7790-5364; Cohn, Stephen/0000-0001-8506-9354 NR 27 TC 5 Z9 5 U1 0 U2 0 PU EUROPEAN GEOPHYSICAL SOC PI KATLENBURG-LINDAU PA MAX-PLANCK-STR 13, 37191 KATLENBURG-LINDAU, GERMANY SN 1023-5809 J9 NONLINEAR PROC GEOPH JI Nonlinear Process Geophys. PD NOV PY 2001 VL 8 IS 6 BP 331 EP 340 PG 10 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 522CH UT WOS:000173877800002 ER PT J AU Davis, MW Olla, BL AF Davis, MW Olla, BL TI Stress and delayed mortality induced in Pacific halibut by exposure to hooking, net towing, elevated seawater temperature and air: Implications for management of bycatch SO NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT LA English DT Article ID OTTER-TRAWL; SABLEFISH; FISHERIES; LONGLINE; SURVIVAL AB The extent of stress and eventual mortality in Pacific halibut Hippoglossus stenolepis that resulted from simulated capture by hooking or towing in a net, followed by abrupt exposure to warmer seawater temperature and air, were determined under laboratory conditions. Abrupt exposure to 16degreesC seawater and air after either method of capture increased capture-induced stress, with accompanying mortality of 33% for hooked fish and 78% for fish towed in a net. Moreover, these deaths occurred as long as 30 d after experimental treatment, Suggesting that delayed mortality should be considered in any study of Pacific halibut bycatch mortality. Stress induced by hooking or towing in a net followed by air exposure was reflected in cessation of negative phototaxis and feeding, both of which were resumed after 5 d with no mortality occurring. The results of this study clearly show that seasonal increases in temperature associated with thermoclines and deck conditions have the potential for markedly increasing the mortality of Pacific halibut that might otherwise survive capture and release in colder seasons. Strategies for effective management of Pacific halibut bycatch need to include consideration of seasonal temperature increases and how this factor might increase mortality. C1 Oregon State Univ, Hatfield Marine Sci Ctr, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Newport, OR 97365 USA. RP Davis, MW (reprint author), Oregon State Univ, Hatfield Marine Sci Ctr, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Newport, OR 97365 USA. NR 23 TC 48 Z9 48 U1 0 U2 4 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 USA SN 0275-5947 J9 N AM J FISH MANAGE JI North Am. J. Fish Manage. PD NOV PY 2001 VL 21 IS 4 BP 725 EP 732 DI 10.1577/1548-8675(2001)021<0725:SADMII>2.0.CO;2 PG 8 WC Fisheries SC Fisheries GA 529FL UT WOS:000174289300003 ER PT J AU Brock, JC Sallenger, AH Krabill, WB Swift, RN Wright, CW AF Brock, JC Sallenger, AH Krabill, WB Swift, RN Wright, CW TI Recognition of fiducial surfaces in lidar surveys of coastal topography SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID AIRBORNE LASER ALTIMETER; VEGETATION; FORESTS AB A new method for the recognition and mapping of surfaces in coastal landscapes that provide accurate and low variability topographic measurements with respect to airborne lidar surveys is described and demonstrated in this paper, Such surfaces are herein termed "fiducial" because they can represent reference baseline morphology in studies of coastal change due to natural or anthropogenic causes, Non-fiducial surfaces may also be identified in each separate lidar survey to be used in a given geomorphic change analysis. Sites that are non-fiducial in either or both lidar surveys that bracket the time period under investigation may be excluded from consideration in subsequent calculations of survey-to-survey elevation differences to eliminate spurious indications of landscape change. This new analysis method, or lidar fiducial surface recognition (LFSR) algorithm, is intended to more fully enable the non-ambiguous use of topographic lidar in a range of coastal investigations. The LFSR algorithm may be widely applied, because it is based solely on the information inherent in the USGS/NASA/NOAA airborne topographic lidar coverage that exists for most of the contiguous U.S. coastline. C1 USGS Ctr Coastal Geol, St Petersburg, FL 33701 USA. NASA, Goddard Space Flight Ctr, Wallops Flight Facil, Wallops Isl, VA 23337 USA. RP Brock, JC (reprint author), USGS Ctr Coastal Geol, 600 4th St S, St Petersburg, FL 33701 USA. NR 29 TC 12 Z9 12 U1 0 U2 1 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 USA SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD NOV PY 2001 VL 67 IS 11 BP 1245 EP 1258 PG 14 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 488GU UT WOS:000171928500005 ER PT J AU Kuryatkov, VV Kipshidze, GD Nikishin, SA Deelman, PW Temkin, H AF Kuryatkov, VV Kipshidze, GD Nikishin, SA Deelman, PW Temkin, H TI AlGaN-based photodetectors grown by gas source molecular beam epitaxy with ammonia SO PHYSICA STATUS SOLIDI A-APPLIED RESEARCH LA English DT Article; Proceedings Paper CT 4th International Conference on Nitride Semiconductors (ICNS-4) CY JUL 16-20, 2001 CL DENVER, COLORADO ID P-I-N AB AlGaN p-n junctions were used to fabricate photodetectors operating between 280 and 380 nm. Detector structures were grown on silicon and sapphire substrates by gas source molecular beam epitaxy with ammonia. Layers of n-AlxGa1-xN (0 less than or equal to x(AlN) less than or equal to 0.08) were grown at a temperature of 800 degreesC on a buffer layer of AIN. The p-type layers of AlxGa1-xN (0 less than or equal to x(AlN) less than or equal to 0.08) were co-doped with Mg and oxygen. Hole concentrations as high. as 2 x 10(18) cm(-3) were measured by capacitance voltage profiling. In the p-Al0.08Ga0.92N layer we measured acceptor activation energy of 195 +/- 10 meV. In a comparable layer of p-GaN, also co-doped with Mg and 0, the acceptor activation energy was 130-165 meV. Low activation energies are attributed to successful co-doping. In mesa etched diodes we measured zero-bias leakage currents as low as 6 x 10(-13) A cm(-2). C1 Texas Tech Univ, Dept Elect & Comp Engn, Lubbock, TX 79401 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Nikishin, SA (reprint author), Texas Tech Univ, Dept Elect & Comp Engn, Lubbock, TX 79401 USA. NR 11 TC 7 Z9 7 U1 0 U2 0 PU WILEY-V C H VERLAG GMBH PI BERLIN PA PO BOX 10 11 61, D-69451 BERLIN, GERMANY SN 0031-8965 J9 PHYS STATUS SOLIDI A JI Phys. Status Solidi A-Appl. Res. PD NOV PY 2001 VL 188 IS 1 BP 317 EP 320 DI 10.1002/1521-396X(200111)188:1<317::AID-PSSA317>3.3.CO;2-G PG 4 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA 501LV UT WOS:000172686900068 ER PT J AU Asztalos, S Daw, E Peng, H Rosenberg, LJ Hagmann, C Kinion, D Stoeffl, W van Bibber, K Sikivie, P Sullivan, NS Tanner, DB Nezrick, F Turner, MS Moltz, DM Powell, J Andre, MO Clarke, J Muck, M Bradley, RF AF Asztalos, S Daw, E Peng, H Rosenberg, LJ Hagmann, C Kinion, D Stoeffl, W van Bibber, K Sikivie, P Sullivan, NS Tanner, DB Nezrick, F Turner, MS Moltz, DM Powell, J Andre, MO Clarke, J Muck, M Bradley, RF TI Large-scale microwave cavity search for dark-matter axions SO PHYSICAL REVIEW D LA English DT Article ID QUANTUM INTERFERENCE DEVICE; ELECTRIC-DIPOLE MOMENT; STRONG CP PROBLEM; INVISIBLE-AXION; COSMIC AXIONS; DC SQUID; RADIOFREQUENCY-AMPLIFIER; GOLDSTONE BOSONS; WEAK-INTERACTION; HARMLESS AXION AB We have built and operated a large-scale axion detector, based on a method originally proposed by Sikivie, to search for halo axions. The apparatus consists of a cylindrical tunable high-Q microwave cavity threaded axially by a static high magnetic field. This field stimulates axions that enter the cavity to convert into single microwave photons. The conversion is resonantly enhanced when the cavity resonant frequency is near the axion rest mass energy. The experiment is cooled to 1.5 K and the electromagnetic power spectrum emitted by the cavity is measured by an ultra-low-noise microwave receiver. The axion would be detected as excess power in a narrow line within the cavity resonance. The apparatus has achieved a power sensitivity better than 10(-23) W in the mass range 2.9-3.3 mu eV. For the first time the rf cavity technique has explored plausible axion models, assuming axions make up a significant fraction of the local halo density. The experiment continues to operate and will explore a large part of the mass in the range of 1-10 mu eV in the near future. An upgrade of the experiment is planned with dc superconducting quantum interference device microwave amplifiers operating at a lower physical temperature. This next generation detector would be sensitive to even more weakly coupled axions contributing only fractionally to the local halo density. C1 MIT, Dept Phys, Cambridge, MA 02139 USA. Lawrence Livermore Natl Lab, Phys & Adv Technol Directorate, Livermore, CA 94550 USA. Univ Florida, Dept Phys, Gainesville, FL 32611 USA. Fermilab Natl Accelerator Lab, NASA, Fermilab Ctr Astrophys, Batavia, IL 60510 USA. Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Enrico Fermi Inst, Dept Phys, Chicago, IL 60637 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Div Nucl Sci, Berkeley, CA 94720 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. MIT, Nucl Sci Lab, Cambridge, MA 02139 USA. RP Asztalos, S (reprint author), MIT, Dept Phys, 77 Massachusetts Ave, Cambridge, MA 02139 USA. NR 83 TC 64 Z9 64 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD NOV 1 PY 2001 VL 64 IS 9 AR 092003 DI 10.1103/PhysRevD.64.092003 PG 28 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 487AT UT WOS:000171852100005 ER PT J AU Beacom, JF Parke, SJ AF Beacom, JF Parke, SJ TI Normalization of the neutrino-deuteron cross section SO PHYSICAL REVIEW D LA English DT Article ID SUPER-KAMIOKANDE; SNO; CONSERVATION; SCATTERING; CAPTURE; REACTOR; PROTON; RATES AB As is well known, the comparison of the solar neutrino fluxes measured in SuperKamiokande (SK) by v+e(-)-->v+e(-) and in the Sudbury Neutrino Observatory (SNO) by v(e)+d -->e(-)+p+p can provide a "smoking gun" signature for neutrino oscillations as the solution to the solar neutrino puzzle. This occurs because SK has some sensitivity to all active neutrino flavors whereas SNO can isolate electron neutrinos. This comparison depends crucially on the normalization and uncertainty of the theoretical charged-current neutrino-deuteron cross section. We address a number of effects which are significant enough to change the interpretation of the SK-SNO comparison. C1 Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Fermilab Natl Accelerator Lab, Dept Theoret Phys, Batavia, IL 60510 USA. RP Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, POB 500, Batavia, IL 60510 USA. EM beacom@fnal.gov; parke@fnal.gov OI Beacom, John/0000-0002-0005-2631 NR 29 TC 32 Z9 32 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0010 EI 2470-0029 J9 PHYS REV D JI Phys. Rev. D PD NOV 1 PY 2001 VL 64 IS 9 AR 091302 PG 3 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 487AT UT WOS:000171852100002 ER PT J AU Exton, RJ Balla, RJ Shirinzadeh, B Brauckmann, GJ Herring, GC Kelliher, WC Fugitt, J Lazard, CJ Khodataev, KV AF Exton, RJ Balla, RJ Shirinzadeh, B Brauckmann, GJ Herring, GC Kelliher, WC Fugitt, J Lazard, CJ Khodataev, KV TI On-board projection of a microwave plasma upstream of a Mach 6 bow shock SO PHYSICS OF PLASMAS LA English DT Article ID WAVE PROPAGATION; BREAKDOWN; AIR; DISCHARGE; NITROGEN; PULSES; FIELD AB High power, pulsed microwaves are beamed forward of a model in a Mach 6 flow using an on-board, Ku-band horn. A thin "precursor" plasma is generated just ahead of the bow shock in the low density free stream. Temporal and spatial analysis of the microwave E-field and plasma conductivity in the supersonic flow field indicate that the plasma reflects a large proportion of the microwave power in an individual pulse as soon as the plasma frequency exceeds the wave frequency. Possible methods for more efficient deposition of power in the free stream are discussed which could lead to increased interaction with the shock. (C) 2001 American Institute of Physics. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. Dept Energy Jefferson Lab, Newport News, VA 23606 USA. Dept Def Army Res Lab, Adelphi, MD 20783 USA. Moscow Radiotech Inst, RAS, Moscow 113519, Russia. RP Exton, RJ (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 43 TC 20 Z9 20 U1 0 U2 4 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1070-664X J9 PHYS PLASMAS JI Phys. Plasmas PD NOV PY 2001 VL 8 IS 11 BP 5013 EP 5017 DI 10.1063/1.1407819 PG 5 WC Physics, Fluids & Plasmas SC Physics GA 483QT UT WOS:000171647800037 ER PT J AU Cline, TL Gehrels, N Lingenfelter, RE AF Cline, TL Gehrels, N Lingenfelter, RE TI Reuven Ramaty - Obituary SO PHYSICS TODAY LA English DT Biographical-Item C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif San Diego, San Diego, CA 92103 USA. RP Cline, TL (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Gehrels, Neil/D-2971-2012 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD NOV PY 2001 VL 54 IS 11 BP 80 EP 80 DI 10.1063/1.1428448 PG 1 WC Physics, Multidisciplinary SC Physics GA 487HC UT WOS:000171867000020 ER PT J AU Dowling, J AF Dowling, J TI Interpreting the interpretations SO PHYSICS WORLD LA English DT Editorial Material C1 NASA, Jet Prop Lab, Quantum Comp Technol Grp, CALTECH, Pasadena, CA USA. RP Dowling, J (reprint author), NASA, Jet Prop Lab, Quantum Comp Technol Grp, CALTECH, Pasadena, CA USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0953-8585 J9 PHYS WORLD JI Phys. World PD NOV PY 2001 VL 14 IS 11 BP 64 EP 64 PG 1 WC Physics, Multidisciplinary SC Physics GA 497NK UT WOS:000172462100029 ER PT J AU Kruger, H Grun, E Graps, A Bindschadler, D Dermott, S Fechtig, H Gustafson, BA Hamilton, DP Hanner, MS Horanyi, M Kissel, J Lindblad, BA Linkert, D Linkert, G Mann, I McDonnell, JAM Morfill, GE Polanskey, C Schwehm, G Srama, R Zook, HA AF Kruger, H Grun, E Graps, A Bindschadler, D Dermott, S Fechtig, H Gustafson, BA Hamilton, DP Hanner, MS Horanyi, M Kissel, J Lindblad, BA Linkert, D Linkert, G Mann, I McDonnell, JAM Morfill, GE Polanskey, C Schwehm, G Srama, R Zook, HA TI One year of Galileo dust data from the Jovian system: 1996 SO PLANETARY AND SPACE SCIENCE LA English DT Article ID ELECTROMAGNETICALLY COUPLED DUST; INTERSTELLAR DUST; ULYSSES; MAGNETOSPHERE; DETECTOR; STREAMS; JUPITER; GRAINS; IO AB The dust detector system onboard Galileo has recoding dust impacts in circumjovian space since the spacecraft was injected into a bound orbit about Jupiter in December 1995. This is the sixth in a series of papers dedicated to presenting Galileo and Ulysses dust data. We present data from the Galileo dust instrument for the period January to December 1996 when the spacecraft completed four orbits about Jupiter (G1, G2, C3 and E4). Data were obtained as high-resolution realtime science data or recorded data during a time period of 100 days, or via memory read-outs during the remaining times. Because the data transmission rate of the spacecraft is very low, the complete data set (i.e. all parameters measured by the instrument during impact of a dust particle) for only 2% (5353) of all particles detected could be transmitted to Earth; the other particles were only counted. Together with the data for 2883 particles detected during Galileo's interplanetary cruise and published earlier, complete data of 8236 particles detected by the Galileo dust instrument from 1989 to 1996 are now available. The majority of particles detected are tiny grains (about 10 nm in radius) originating from Jupiter's innermost Galilean moon lo. These grains have been detected throughout the Jovian system and the highest impact rates exceeded 100 min(-1). A small number of grains has been detected in the close vicinity of the Galilean moons Europa, Ganymede and Callisto which belong to impact-generated dust clouds formed by (mostly submicrometer sized) ejecta from the surfaces of the moons (Kruger et al., 1999e. Nature 399, 558). Impacts of submicrometer to micrometer sized grains have been detected throughout the Jovian system and especially in the region between the Galilean moons. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Max Planck Inst Kernphys, D-69029 Heidelberg, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Florida, Gainesville, FL 32611 USA. Univ Maryland, College Pk, MD 20742 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. Max Planck Inst Extraterr Phys, D-85748 Garching, Germany. Lund Observ, S-221 Lund, Sweden. Univ Munster, Inst Planetol, D-48149 Munster, Germany. European Space Agcy, ESTEC, NL-2200 AG Noordwijk, Netherlands. Open Univ, Planetary & Space Sci Res Inst, Milton Keynes MK7 6AA, Bucks, England. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Kruger, H (reprint author), Max Planck Inst Kernphys, Postfach 10 39 80, D-69029 Heidelberg, Germany. RI Gustafson, Bo/B-9526-2011; OI Horanyi, Mihaly/0000-0002-5920-9226 NR 31 TC 19 Z9 19 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD NOV PY 2001 VL 49 IS 13 BP 1285 EP 1301 DI 10.1016/S0032-0633(01)00053-8 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 470VE UT WOS:000170891200005 ER PT J AU Kruger, H Grun, E Landgraf, M Dermott, S Fechtig, H Gustafson, BA Hamilton, DP Hanner, MS Horanyi, M Kissel, J Lindblad, BA Linkert, D Linkert, G Mann, I McDonnell, JAM Morfill, GE Polanskey, C Schwehm, G Srama, R Zook, HA AF Kruger, H Grun, E Landgraf, M Dermott, S Fechtig, H Gustafson, BA Hamilton, DP Hanner, MS Horanyi, M Kissel, J Lindblad, BA Linkert, D Linkert, G Mann, I McDonnell, JAM Morfill, GE Polanskey, C Schwehm, G Srama, R Zook, HA TI Four years of Ulysses dust data: 1996-1999 SO PLANETARY AND SPACE SCIENCE LA English DT Article ID INTERSTELLAR DUST; MASS-DISTRIBUTION; GALILEO; GRAINS; DETECTOR; HELIOSPHERE; METEOROIDS; JUPITER; STREAMS; BELT AB The Ulysses spacecraft is orbiting the Sun on a highly inclined ellipse (i = 79 degrees, perihelion distance 1.3 AU, aphelion distance 5.4 AU). Between January 1996 and December 1999 the spacecraft was beyond 3 AU from the Sun and crossed the ecliptic plane at aphelion in May 1998. In this 4-yr period 218 dust impacts were recorded with the dust detector on board. We publish and analyse the complete data set of both raw and reduced data for particles with masses 10(-16)-10(-8) g. Together with 1477 dust impacts recorded between launch of Ulysses and the end of 1995 published earlier (Grun et al., Planet. Space Sci. 43 (1995a) 971; Kruger et al., Planet. Space Sci. 47 (1999b) 363), a data set of 1695 dust impacts detected with the Ulysses sensor between October 1990 and December 1999 is now available. The impact rate measured between 1996 and 1999 was relatively constant with about 0.2 impacts per day. The impact direction of the majority of the impacts is compatible with particles of interstellar origin, the rest are most likely interplanetary particles. The observed impact rate is compared with a model for the flux of interstellar dust particles. The flux of particles several micrometres in size is compared with the measurements of the dust instruments on board Pioneer 10 and Pioneer 11 beyond 3 AU (Humes, J. Geophys. Res. 85 (1980) 5841). Between 3 and 5 AU, Pioneer results predict that Ulysses should have seen 5 times more (similar to 10 mum sized) particles than actually detected. (C) 2001 Published by Elsevier Science Ltd. C1 Max Planck Inst Kernphys, D-69029 Heidelberg, Germany. ESOC, D-64293 Darmstadt, Germany. Univ Florida, Gainesville, FL 32611 USA. Univ Maryland, College Pk, MD 20742 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. Max Planck Inst Extraterr Phys, D-85748 Garching, Germany. Lund Observ, S-221 Lund, Sweden. Univ Munster, Inst Planetol, D-48149 Munster, Germany. Open Univ, Planetary & Space Sci Res Inst, Milton Keynes MK7 6AA, Bucks, England. European Space Agcy, ESTEC, NL-2200 AG Noordwijk, Netherlands. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Kruger, H (reprint author), Max Planck Inst Kernphys, D-69029 Heidelberg, Germany. EM harald.krueger@mpi-hd.mpg.de RI Gustafson, Bo/B-9526-2011; OI Horanyi, Mihaly/0000-0002-5920-9226 NR 46 TC 24 Z9 24 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD NOV PY 2001 VL 49 IS 13 BP 1303 EP 1324 DI 10.1016/S0032-0633(01)00054-X PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 470VE UT WOS:000170891200006 ER PT J AU Diedrichsen, J Hazeltine, E Kennerley, S Ivry, RB AF Diedrichsen, J Hazeltine, E Kennerley, S Ivry, RB TI Moving to directly cued locations abolishes spatial interference during bimanual actions SO PSYCHOLOGICAL SCIENCE LA English DT Article ID STRUCTURAL CONSTRAINTS; DIFFERENT AMPLITUDES; MOVEMENTS; SPECIFICATION; TASK; SUPPLEMENTARY; COORDINATION; PERFORMANCE AB Interference is frequently observed during bimanual movements if the two hands perform nonsymmetric actions. We examined the source of bimanual interference in two experiments in which we compared conditions involving symmetric movements with conditions in which the movements were of different amplitudes or different directions. The target movements were cued either symbolically by letters or directly by the onset of the target locations. With symbolic cues, reaction times were longer when the movements of the two hands were not symmetric. With direct cues, reaction times it-ere the same for symmetric and nonsymmetric movements. These results indicate that directly cued actions can be programmed in parallel for the two hands. Our results challenge the hypothesis that the cost to initiate nonsymmetric movements is due to spatial interference in a motor-programming stage. Rather the cost appears to he caused by stimulus identification, response-selection processes connected to the processing of symbolic cues, or both. C1 Univ Calif Berkeley, Dept Psychol, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Diedrichsen, J (reprint author), Univ Calif Berkeley, Dept Psychol, 3210 Tolman Hall, Berkeley, CA 94720 USA. RI Diedrichsen, Jorn/A-7789-2010; OI Diedrichsen, Jorn/0000-0003-0264-8532; Hazeltine, Richard/0000-0002-0893-5789 FU NINDS NIH HHS [NS 1778, NS 30256] NR 18 TC 87 Z9 87 U1 0 U2 6 PU BLACKWELL PUBLISHERS PI MALDEN PA 350 MAIN STREET, STE 6, MALDEN, MA 02148 USA SN 0956-7976 J9 PSYCHOL SCI JI Psychol. Sci. PD NOV PY 2001 VL 12 IS 6 BP 493 EP 498 DI 10.1111/1467-9280.00391 PG 6 WC Psychology, Multidisciplinary SC Psychology GA 491MQ UT WOS:000172112700010 PM 11760137 ER PT J AU Remington, RW Folk, CL AF Remington, RW Folk, CL TI A dissociation between attention and selection SO PSYCHOLOGICAL SCIENCE LA English DT Article ID CONTEXTUAL FACILITATION; AUTOMATIC PROCESSES; VISUAL INFORMATION; PERCEPTUAL LOAD; SEARCH TASK; OBJECTS; COLOR; ORGANIZATION; CONTINGENT; ACTIVATION AB It is widely assumed that the allocation of spatial attention results in the "selection" of attended objects or regions of space. That is, once a stimulus is attended, all its feature dimensions are processed irrespective of their relevance to behavioral goals. This assumption is based in part on experiments showing significant interference for attended stimuli when the response to an irrelevant dimension conflicts with the response to the relevant dimension (e.g., the Stroop effect). Here we show that such interference is not due to attending per se. In two spatial citing experiments, we found that it was possible to restrict processing of attended stimuli to task-relevant dimensions. This new evidence supports two novel conclusions: (a) Selection involves more than the focusing of attention per se; and (b) task expectations play a kev role in determining the depth of processing of the elementary feature dimensions of attended stimuli. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Villanova Univ, Villanova, PA 19085 USA. RP Remington, RW (reprint author), NASA, Ames Res Ctr, MS 262-4, Moffett Field, CA 94035 USA. RI Martin Arevalo, Elisa/L-4472-2014 OI Martin Arevalo, Elisa/0000-0002-4546-6440 NR 33 TC 41 Z9 41 U1 0 U2 5 PU BLACKWELL PUBLISHERS PI MALDEN PA 350 MAIN STREET, STE 6, MALDEN, MA 02148 USA SN 0956-7976 J9 PSYCHOL SCI JI Psychol. Sci. PD NOV PY 2001 VL 12 IS 6 BP 511 EP 515 DI 10.1111/1467-9280.00394 PG 5 WC Psychology, Multidisciplinary SC Psychology GA 491MQ UT WOS:000172112700013 PM 11760140 ER PT J AU Ziegler, MG Meck, JV AF Ziegler, MG Meck, JV TI Physical and psychological challenges of space travel: An overview SO PSYCHOSOMATIC MEDICINE LA English DT Editorial Material C1 Univ Calif San Diego, Dept Med, San Diego, CA 92103 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Ziegler, MG (reprint author), Univ Calif San Diego, Dept Med, 200 W Arbor, San Diego, CA 92103 USA. NR 7 TC 2 Z9 2 U1 1 U2 2 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0033-3174 J9 PSYCHOSOM MED JI Psychosom. Med. PD NOV-DEC PY 2001 VL 63 IS 6 BP 859 EP 861 PG 3 WC Psychiatry; Psychology; Psychology, Multidisciplinary SC Psychiatry; Psychology GA 497MY UT WOS:000172460700001 PM 11719621 ER PT J AU Styf, JR Hutchinson, K Carlsson, SG Hargens, AR AF Styf, JR Hutchinson, K Carlsson, SG Hargens, AR TI Depression, mood state, and back pain during microgravity simulated by bed rest SO PSYCHOSOMATIC MEDICINE LA English DT Editorial Material DE depression; mood; lower back pain; lower abdominal pain; leg pain; bed rest ID HEAD-DOWN TILT; FLUID SHIFTS AB Objective: The objective of this study was to develop a ground-based model for spinal adaption to microgravity and to study the effects of spinal adaptation on depression, mood state, and pain intensity. Methods: We investigated back pain, mood state, and depression in six subjects, all of whom were exposed to microgravity, simulated by two forms of bed rest, for 3 days. One form consisted of bed rest with 6 degrees of head-down tilt and balanced traction, and the other consisted of horizontal bed rest. Subjects had a 2-week period of recovery between the studies. The effects of bed rest on pain intensity in the lower back, depression, and mood state were investigated. Results: Subjects experienced significantly more intense lower back pain, lower hemisphere abdominal pain, headache, and log pain during head-down tilt bed rest. They had higher scores on the Beck Depression Inventory (ie, were more depressed) and significantly lower scores on the activity scale of the Bond-Lader questionnaire. Conclusions: Bed rest with 6 degrees of head-down tilt may be a better experimental model than horizontal bed rest for inducing the pain and psychosomatic reactions experienced in microgravity. Head-down tilt with balanced traction may be a useful method to induce low back pain, mood changes, and altered self-rated activity level in bed rest studies. Key words: depression, mood, lower back pain, lower abdominal pain, leg pain, bed rest. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Univ Gothenburg, Inst Psychol, Gothenburg, Sweden. RP Styf, JR (reprint author), Sahlgrens Univ Hosp, Dept Orthopaed, Guldhedsg 19, S-41346 Gothenburg, Sweden. NR 14 TC 25 Z9 27 U1 0 U2 3 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0033-3174 J9 PSYCHOSOM MED JI Psychosom. Med. PD NOV-DEC PY 2001 VL 63 IS 6 BP 862 EP 864 PG 3 WC Psychiatry; Psychology; Psychology, Multidisciplinary SC Psychiatry; Psychology GA 497MY UT WOS:000172460700002 PM 11719622 ER PT J AU Meck, JV Reyes, CJ Perez, SA Goldberger, AL Ziegler, MG AF Meck, JV Reyes, CJ Perez, SA Goldberger, AL Ziegler, MG TI Marked exacerbation of orthostatic intolerance after long- vs. short-duration spaceflight in veteran astronauts SO PSYCHOSOMATIC MEDICINE LA English DT Editorial Material DE autonomic nervous system; long-duration spaceflight; microgravity; plasma volume; presyncope; tilt testing ID FLIGHT AB Objective: The incidence of postflight orthostatic intolerance after short-duration spaceflight is about 20%. However, the incidence after long-duration spaceflight was unknown. The purpose of this study was to test the hypothesis that orthostatic intolerance is more severe after long-duration than after short-duration flight. Methods: We performed tilt tests on six astronauts before and after long-duration (129-190 days) spaceflights and compared these data with data obtained during stand tests before and after previous short-duration missions. Results: Five of the six astronauts studied became presyncopal during tilt testing after long-duration flights. Only one had become presyncopal during stand testing after short-duration flights. We also compared the long-duration flight tilt test data to tilt test data from 20 different astronauts who flow on the short-duration Shuttle missions that delivered and recovered the astronauts to and from the Mir Space Station. Five of these 20 astronauts became presyncopal on landing day. Heart rate responses to tilt were no different between astronauts on long-duration flights and astronauts on short-duration flights, but long-duration subjects had lower stroke volumes and cardiac outputs than short-duration presyncopal subjects, suggesting a possible decrease in cardiac contractile function. One subject had subnormal norepinephrine release with upright posture after the long flight but not after the short flight. Plasma volume losses were not greater after long flights. Conclusion: Long-duration spaceflight markedly increases orthostatic intolerance, probably with multiple contributing factors. C1 NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Wyle Labs, Houston, TX USA. Harvard Univ, Beth Israel Deaconess Med Ctr, Sch Med, Boston, MA 02215 USA. Univ Calif San Diego, La Jolla, CA 92093 USA. RP Meck, JV (reprint author), NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Mail Code SD361, Houston, TX 77058 USA. FU NCRR NIH HHS [M01 RR00827] NR 17 TC 61 Z9 62 U1 4 U2 5 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0033-3174 J9 PSYCHOSOM MED JI Psychosom. Med. PD NOV-DEC PY 2001 VL 63 IS 6 BP 865 EP 873 PG 9 WC Psychiatry; Psychology; Psychology, Multidisciplinary SC Psychiatry; Psychology GA 497MY UT WOS:000172460700003 PM 11719623 ER PT J AU Kanas, N Salnitskiy, V Gushin, V Weiss, DS Grund, EM Flynn, C Kozerenko, O Sled, A Marmar, CR AF Kanas, N Salnitskiy, V Gushin, V Weiss, DS Grund, EM Flynn, C Kozerenko, O Sled, A Marmar, CR TI Asthenia - Does it exist in space? SO PSYCHOSOMATIC MEDICINE LA English DT Article; Proceedings Paper CT 71st Annual Scientific Meeting of the Aerospace-Medical-Association CY MAY 14-18, 2000 CL HOUSTON, TEXAS SP Aerospace Med Assoc DE asthenia; neurasthenia; psychosomatic; space; astronaut; cosmonaut ID COSMONAUTS; ASTRONAUTS; COMMUNICATION; MISSIONS; ISSUES AB Objective: First popularized as neurasthenia in the late 1800s by American George Beard, asthenia has been viewed by Russian psychologists and flight Surgeons as a major problem that affects cosmonauts participating in long-duration space missions. However, there is some controversy about whether this syndrome exists in space; this controversy is attributable in part to the fact that it is not recognized in the current American psychiatric diagnostic system. Methods: To address this issue empirically, we retrospectively examined the data from our 4 1/2-year, NASA-funded study of crew member and mission control interactions during the Shuttle/Mir space program. Three of the authors identified eight items of stage 1 asthenia from one of our measures, the Profile of Mood States (POMS). Scores on these items from 13 Russian and American crew members were compared with scores derived from the opinions of six Russian space experts. Results: Crew members' scores in space were significantly lower than the experts' scores on seven of the eight items, and they generally were in the "not at all" to "a little" range of the item scales. There were no differences in mean scores before and after launch or across the four quarters of the missions. There were no differences in response between Russian and American crew members. Conclusions: We could not demonstrate the presence of asthenia in space as operationally defined using the POMS. However, the POMS addresses only emotional and not physiological aspects of the syndrome, and the subject responses in our study generally were skewed toward the positive end of the scales. Further research on this syndrome needs to be done and should include physiological measures and measures that are specific to asthenia. C1 Univ Calif San Francisco, VA Med Ctr 116A, Dept Psychiat, San Francisco, CA 94121 USA. Univ Calif San Francisco, Dept Vet Affairs Med Ctr, San Francisco, CA 94121 USA. Inst Biomed Problems, Moscow, Russia. Lyndon B Johnson Space Ctr, Houston, TX USA. RP Kanas, N (reprint author), Univ Calif San Francisco, VA Med Ctr 116A, Dept Psychiat, 4150 Clement St, San Francisco, CA 94121 USA. NR 33 TC 22 Z9 25 U1 1 U2 3 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0033-3174 J9 PSYCHOSOM MED JI Psychosom. Med. PD NOV-DEC PY 2001 VL 63 IS 6 BP 874 EP 880 PG 7 WC Psychiatry; Psychology; Psychology, Multidisciplinary SC Psychiatry; Psychology GA 497MY UT WOS:000172460700004 PM 11719624 ER PT J AU Mills, PJ Meck, JV Waters, WW D'Aunno, D Ziegler, MG AF Mills, PJ Meck, JV Waters, WW D'Aunno, D Ziegler, MG TI Peripheral leukocyte subpopulations and catecholamine levels in astronauts as a function of mission duration SO PSYCHOSOMATIC MEDICINE LA English DT Editorial Material DE spaceflight; leukocytes; lymphocytes; catecholamines; stress ID TERM SPACEFLIGHT; SPACE-FLIGHT; IMMUNE; STRESS; EXERCISE; NOREPINEPHRINE; MECHANISMS; RESPONSES; PRESSURE; RELEASE AB Objective: The objective of this study was to determine the effects of spaceflight duration on immune cells and their relationship to catecholamine levels. Methods: Eleven astronauts who flew aboard five different US Space Shuttle flights ranging in duration from 4 to 16 days were studied before launch and after landing. Results: Consistent with prior studies, spaceflight was associated with a significant increase in the number of circulating white blood cells (p < .01), including neutrophils (p < .01), monocytes (p < .05), CD3(+)CD4(+) T-helper cells (p < .05), and CD19(+) B cells (p < .01). In contrast, the number of CD3(-)CD16(+)56(+) natural killer cells was decreased (p < .01). Plasma norepinephrine levels were increased at landing (p < .01) and were significantly correlated with the number of white blood cells (p < .01), neutrophils (p < .01), monocytes (p < .01), and B cells (p < .01). Astronauts who were in space for approximately 1 week showed a significantly larger increase on landing in plasma norepinephrine (p = .02) and epinephrine (p = .03) levels, as well as number of circulating CD3(+)CD4(+.) T-helper cells (p < .05) and CD3(+)CD8(+) T-cytotoxic cells (p < .05) as compared with astronauts in space for approximately 2 weeks. Conclusions: The data suggest that the stress of spaceflight and landing may lead to a sympathetic nervous system-mediated redistribution of circulating leukocytes, an effect potentially attenuated after longer missions. Key words: spaceflight, leukocytes, lymphocytes, catecholamines, stress. C1 Univ Calif San Diego, Med Ctr, Dept Psychiat, San Diego, CA 92103 USA. Univ Calif San Diego, Med Ctr, Dept Med, San Diego, CA 92103 USA. Lyndon B Johnson Space Ctr, Cardiovasc Lab, Houston, TX USA. Baylor Coll Med, Natl Space Biomed Res Inst, Houston, TX 77030 USA. RP Mills, PJ (reprint author), Univ Calif San Diego, Med Ctr, Dept Psychiat, 200 W Arbor Dr, San Diego, CA 92103 USA. FU NCRR NIH HHS [MO1RR00827]; NHLBI NIH HHS [HL57265] NR 28 TC 30 Z9 34 U1 0 U2 2 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0033-3174 J9 PSYCHOSOM MED JI Psychosom. Med. PD NOV-DEC PY 2001 VL 63 IS 6 BP 886 EP 890 PG 5 WC Psychiatry; Psychology; Psychology, Multidisciplinary SC Psychiatry; Psychology GA 497MY UT WOS:000172460700006 PM 11719626 ER PT J AU Stowe, RP Pierson, DL Barrett, ADT AF Stowe, RP Pierson, DL Barrett, ADT TI Elevated stress hormone levels relate to Epstein-Barr virus reactivation in astronauts SO PSYCHOSOMATIC MEDICINE LA English DT Editorial Material DE Epstein-Barr virus; stress; spaceflight; microgravity; viral immunity ID SHORT-TERM SPACEFLIGHT; TRANSPLANT RECIPIENTS; CD4(+) LYMPHOCYTES; INDUCED MODULATION; IL-12 PRODUCTION; NUCLEAR ANTIGEN; SPACE-FLIGHT; RESPONSES; IMMUNITY; GLUCOCORTICOIDS AB Objective: The objective of this study was to determine the effects of stress and spaceflight on levels of neuroendocrine hormones and Epstein-Barr virus (EBV)-specific antibodies in astronauts. Methods: Antiviral antibody titers and stress hormones were measured in plasma samples collected from 28 astronauts at their annual medical exam (baseline), 10 days before launch (L-10), landing day (R+0), and 3 days after landing (R+3). Urinary stress hormones were also measured at L-10 and R+0. Results: Significant increases (p < .01) in EBV virus capsid antigen antibodies were found at all three time points (L-10, R+0, and R+3) as compared with baseline samples. A-nti-EBV nuclear antigen antibodies were significantly decreased at L-10 (p < .05) and continued to decrease after spaceflight (R+0 and R+3, p < .01). No changes were found in antibodies to the nonlatent measles virus. The 11 astronauts who showed evidence of EBV reactivation had significant increases in urinary epinephrine and norepinephrine as compared with astronauts without EBV reactivation. Conclusion: These findings indicate that physical and psychological stresses associated with spaceflight resulted in decreased virus-specific T-cell immunity and reactivation of EBV. C1 Univ Texas, Med Branch, Dept Pathol, Galveston, TX 77555 USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. RP Stowe, RP (reprint author), Univ Texas, Med Branch, Dept Pathol, Galveston, TX 77555 USA. NR 30 TC 64 Z9 66 U1 0 U2 6 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0033-3174 J9 PSYCHOSOM MED JI Psychosom. Med. PD NOV-DEC PY 2001 VL 63 IS 6 BP 891 EP 895 PG 5 WC Psychiatry; Psychology; Psychology, Multidisciplinary SC Psychiatry; Psychology GA 497MY UT WOS:000172460700007 PM 11719627 ER PT J AU Kok, P Lee, H Cerf, NJ Dowling, JP AF Kok, Pieter Lee, Hwang Cerf, Nicholas J. Dowling, Jonathan P. TI PERSPECTIVE: Long-distance quantum communication just around the corner? SO QUANTUM INFORMATION & COMPUTATION LA English DT Article ID PODOLSKY-ROSEN CHANNELS; FIBER; CRYPTOGRAPHY; TELEPORTATION; STORAGE; STATE; LIGHT AB Optical communication channels over long distances have always been plagued by coherence loss and attenuation. This seriously compromises their use for quantum communication. Now, researchers from Innsbruck and Harvard have found a new and efficient way to stretch these quantum channels by using entangled atomic ensembles. C1 [Kok, Pieter; Lee, Hwang; Cerf, Nicholas J.; Dowling, Jonathan P.] CALTECH, Jet Prop Lab, Quantum Comp Technol Grp, Pasadena, CA 91109 USA. RP Kok, P (reprint author), CALTECH, Jet Prop Lab, Quantum Comp Technol Grp, Mail Stop 126-347,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 0 Z9 0 U1 0 U2 0 PU RINTON PRESS, INC PI PARAMUS PA 565 EDMUND TERRACE, PARAMUS, NJ 07652 USA SN 1533-7146 J9 QUANTUM INF COMPUT JI Quantum Inform. Comput. PD NOV PY 2001 VL 1 IS 3 BP 87 EP 88 PG 2 WC Computer Science, Theory & Methods; Physics, Particles & Fields; Physics, Mathematical SC Computer Science; Physics GA V31RW UT WOS:000208901700008 ER PT J AU Cucinotta, FA Manuel, FK Jones, J Iszard, G Murrey, J Djojonegro, B Wear, M AF Cucinotta, FA Manuel, FK Jones, J Iszard, G Murrey, J Djojonegro, B Wear, M TI Space radiation and cataracts in astronauts SO RADIATION RESEARCH LA English DT Article ID BEAVER DAM EYE; ACCELERATED HEAVY-PARTICLES; LENS OPACITIES; IRRADIATION; PREVALENCE; POPULATION; NUCLEAR; RAYS; CELL AB For over 30 years, astronauts in Earth orbit or on missions to the moon have been exposed to space radiation comprised of high-energy protons and heavy ions and secondary particles produced in collisions with spacecraft and tissue. Large uncertainties exist in the projection of risks of late effects from space radiation such as cancer and cataracts due to the absence of epidemiological data. Here we present the first epidemiological data linking an increased risk of cataracts for astronauts with higher lens doses (>8 mSv) of space radiation relative to other astronauts with lower lens doses (<8 mSv). Our study uses historical data for cataract incidence in the 295 astronauts participating in NASA's Longitudinal Study of Astronaut Health (LSAH) and individual occupational radiation exposure data. These results, while preliminary because of the use of subjective scoring methods, suggest that relatively low doses of space radiation are causative of an increased incidence and early appearance of cataracts. (C) 2001 by Radiation Research Society. C1 NASA, Lyndon B Johnson Space Ctr, Space & Life Sci Directorate, Houston, TX 77058 USA. Kelsey Seybold Clin, Houston, TX 77058 USA. Wyle Labs, Houston, TX 77058 USA. RP Cucinotta, FA (reprint author), NASA, Lyndon B Johnson Space Ctr, Space & Life Sci Directorate, Houston, TX 77058 USA. NR 38 TC 134 Z9 144 U1 0 U2 12 PU RADIATION RESEARCH SOC PI OAK BROOK PA 820 JORIE BOULEVARD, OAK BROOK, IL 60523 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD NOV PY 2001 VL 156 IS 5 BP 460 EP 466 DI 10.1667/0033-7587(2001)156[0460:SRACIA]2.0.CO;2 PN 1 PG 7 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 489NZ UT WOS:000171999000002 PM 11604058 ER PT J AU Ponomarev, AL Cucinotta, FA Sachs, RK Brenner, DJ Peterson, LE AF Ponomarev, AL Cucinotta, FA Sachs, RK Brenner, DJ Peterson, LE TI Extrapolation of the DNA fragment-size distribution after high-dose irradiation to predict effects at low doses SO RADIATION RESEARCH LA English DT Article ID LINEAR-ENERGY-TRANSFER; DOUBLE-STRAND BREAKS; RADIATION; MODEL; CHROMOSOMES; POLYMER; CELLS AB The patterns of DSBs induced in the genome are different for sparsely and densely ionizing radiations: In the former case, the patterns are well described by a random-breakage model; in the latter, a more sophisticated tool is needed. We used a Monte Carlo algorithm with a random-walk geometry of chromatin, and a track structure defined by the radial distribution of energy deposition from an incident ion, to fit the PFGE data for fragment-size distribution after high-dose irradiation. These fits determined the unknown parameters of the model, enabling the extrapolation of data for high-dose irradiation to the low doses that are relevant for NASA space radiation research. The randomly-located-clusters formalism was used to speed the simulations. It was shown that only one adjustable parameter, Q, the track efficiency parameter, was necessary to predict DNA fragment sizes for wide ranges of doses. This parameter was determined for a variety of radiations and LETS and was used to predict the DSB patterns at the HPRT locus of the human X chromosome after low-dose irradiation. It was found that high-LET radiation would be more likely than low-LET radiation to induce additional DSBs within the HPRT gene if this gene already contained one DSB. (C) 2001 by Radiation Research Society. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Calif Berkeley, Dept Math, Berkeley, CA 94720 USA. Columbia Univ, Ctr Radiol Res, New York, NY 10032 USA. Baylor Coll Med, Houston, TX 77030 USA. RP Ponomarev, AL (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SN, Houston, TX 77058 USA. OI Peterson, Leif/0000-0002-1187-0883 FU NCI NIH HHS [CA-77285, CA-24232, CA-49062]; NCRR NIH HHS [RR-11623]; NIEHS NIH HHS [ES-07361] NR 14 TC 12 Z9 12 U1 0 U2 3 PU RADIATION RESEARCH SOC PI OAK BROOK PA 820 JORIE BOULEVARD, OAK BROOK, IL 60523 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD NOV PY 2001 VL 156 IS 5 BP 594 EP 597 DI 10.1667/0033-7587(2001)156[0594:EOTDFS]2.0.CO;2 PN 2 PG 4 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 489PB UT WOS:000171999200006 PM 11604078 ER PT J AU Kawata, T Durante, M Furusawa, Y George, K Ito, H Wu, H Cucinotta, FA AF Kawata, T Durante, M Furusawa, Y George, K Ito, H Wu, H Cucinotta, FA TI Rejoining of isochromatid breaks induced by heavy ions in G(2)-phase normal human fibroblasts SO RADIATION RESEARCH LA English DT Article ID PREMATURE CHROMOSOME CONDENSATION; TUMOR-CELL LINES; HUMAN-LYMPHOCYTES; CHROMATID DAMAGE; LET RADIATION; V79 CELLS; X-RAYS; ABERRATIONS; IRRADIATION; INDUCTION AB We reported previously that exposure of normal human fibroblasts in G(2) phase of the cell cycle to high-LET radiation produces a much higher frequency of isochromatid breaks than exposure to gamma rays. We concluded that an increase in the production of isochromatid breaks is a signature of initial high-LET radiation-induced G(2)-phase damage. In this paper, we report the repair kinetics of isochromatid breaks induced by high-LET radiation in normal G(2)-phase human fibroblasts. Exponentially growing human fibroblasts (AG1522) were irradiated with gamma rays or energetic carbon (290 MeV/nucleon), silicon (490 MeV/nucleon), or iron (200 MeV/nueleon) ions. Prematurely condensed chromosomes were induced by calyculin A after different postirradiation incubation times ranging from 0 to 600 min. Chromosomes were stained with Giemsa, and aberrations were scored in cells at G(2) phase. G(2)-phase fragments, the result of the induction of isochromatid breaks, decreased quickly with incubation time. The curve for the kinetics of the rejoining of chromatid-type breaks showed a slight upward curvature with time after exposure to 440 keV/mum iron particles, probably due to isochromatid-isochromatid break rejoining. The formation of chromatid exchanges after exposure to high-LET radiation therefore appears to be underestimated, because isochromatid-isochromatid exchanges cannot be detected. Increased induction of isochromatid breaks and rejoining of isochromatid breaks affect the overall kinetics of chromatid-type break rejoining after exposure to high-LET radiation. (C) 2001 by Radiation Research Society. C1 NASA, Lyndon B Johnson Space Ctr, Radiat Biophys Lab, Houston, TX 77058 USA. Univ Space Res Assoc, Houston, TX USA. Univ Naples Federico II, Dept Phys, Naples, Italy. Natl Inst Radiol Sci, Int Space Radiat Lab, Chiba 260, Japan. Wyle Labs, Houston, TX USA. Chiba Univ, Dept Radiol, Chiba 280, Japan. Kelsey Seybold Clin, Houston, TX USA. RP Kawata, T (reprint author), NASA, Lyndon B Johnson Space Ctr, Radiat Biophys Lab, Mail Code SN, Houston, TX 77058 USA. RI Durante, Marco/K-1315-2014; OI Durante, Marco/0000-0002-4615-553X NR 23 TC 14 Z9 19 U1 0 U2 0 PU RADIATION RESEARCH SOC PI OAK BROOK PA 820 JORIE BOULEVARD, OAK BROOK, IL 60523 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD NOV PY 2001 VL 156 IS 5 BP 598 EP 602 DI 10.1667/0033-7587(2001)156[0598:ROIBIB]2.0.CO;2 PN 2 PG 5 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 489PB UT WOS:000171999200007 PM 11604079 ER PT J AU Wu, HL AF Wu, HL TI Probabilities of radiation-induced inter- and intrachromosomal exchanges and their dependence on the DNA content of the chromosome SO RADIATION RESEARCH LA English DT Article ID TRUE INCOMPLETE EXCHANGES; IONIZING-RADIATION; HUMAN-LYMPHOCYTES; ABERRATIONS; HYBRIDIZATION; FREQUENCY; CHROMATIN; EXPOSURE; GEOMETRY; DOMAINS AB A biophysical model has been developed that is based on the assumptions that an interphase chromosome occupies a spherical territory and that chromosome exchanges are formed by the misrejoining of two DNA double-strand breaks induced within a defined interaction distance. The model is used to explain the relative frequencies of inter- and intrachromosomal exchanges and the relationship between radiation-induced aberrations in individual chromosomes and the DNA content of the chromosome. Although this simple model predicts a higher ratio of inter- to intrachromosomal exchanges for low-LET radiation than for high-LET radiation, as has been suggested by others, we argue that the comparison of the prediction of the model with experimental results is not straightforward. With the model, we also show that the probability of the formation of interchromosomal exchanges is proportional to the "surface area" of the chromosome domain plus a correction term. The correction term is small if the interaction distance is less than 1 mum for both low- and high-LET radiations. (C) 2001 by Radiation Research Society. C1 NASA, Lyndon B Johnson Space Ctr, Kelsey Seybold Clin, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Radiat Biophys Lab, Houston, TX 77058 USA. RP Wu, HL (reprint author), NASA, Lyndon B Johnson Space Ctr, Kelsey Seybold Clin, Mail Code SD23, Houston, TX 77058 USA. NR 20 TC 7 Z9 7 U1 0 U2 0 PU RADIATION RESEARCH SOC PI OAK BROOK PA 820 JORIE BOULEVARD, OAK BROOK, IL 60523 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD NOV PY 2001 VL 156 IS 5 BP 603 EP 606 DI 10.1667/0033-7587(2001)156[0603:PORIIA]2.0.CO;2 PN 2 PG 4 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 489PB UT WOS:000171999200008 PM 11604080 ER PT J AU Durante, M Bonassi, S George, K Cucinotta, FA AF Durante, M Bonassi, S George, K Cucinotta, FA TI Risk estimation based on chromosomal aberrations induced by radiation SO RADIATION RESEARCH LA English DT Article ID ATOMIC-BOMB SURVIVORS; PREDICT HUMAN CANCER; LYMPHOCYTES; EXPOSURE; SHUTTLE; HEALTH; ASTRONAUTS; MORTALITY; SPECTRA; STATION AB The presence of a causal association between the frequency of chromosomal aberrations in peripheral blood lymphocytes and the risk of cancer has been substantiated recently by epidemiological studies. Cytogenetic analyses of crew members of the Mir Space Station have shown that a significant increase in the frequency of chromosomal aberrations can be detected after flight, and that such an increase is likely to be attributed to the radiation exposure. The risk of cancer can be estimated directly from the yields of chromosomal aberrations, taking into account some aspects of individual susceptibility and other factors unrelated to radiation. However, the use of an appropriate technique for the collection and analysis of chromosomes and the choice of the structural aberrations to be measured are crucial in providing sound results. Based on the fraction of aberrant lymphocytes detected before and after flight, the relative risk after a long-term Mir mission is estimated to be about 1.2-1.3. The new technique of mFISH can provide useful insights into the quantification of risk on an individual basis. (C) 2001 by Radiation Research Society. C1 Univ Naples Federico II, Dipartimento Sci Fis, I-80126 Naples, Italy. Ist Nazl Ric Canc, I-16151 Genoa, Italy. Wyle Labs, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Durante, M (reprint author), Univ Naples Federico II, Dipartimento Sci Fis, Monte S Angelo,Via Cintia, I-80126 Naples, Italy. RI Durante, Marco/K-1315-2014; OI bonassi, stefano/0000-0003-3833-6717; Durante, Marco/0000-0002-4615-553X NR 30 TC 46 Z9 48 U1 0 U2 2 PU RADIATION RESEARCH SOC PI OAK BROOK PA 820 JORIE BOULEVARD, OAK BROOK, IL 60523 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD NOV PY 2001 VL 156 IS 5 BP 662 EP 667 DI 10.1667/0033-7587(2001)156[0662:REBOCA]2.0.CO;2 PN 2 PG 6 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 489PB UT WOS:000171999200017 PM 11604089 ER PT J AU Cucinotta, FA Schimmerling, W Wilson, JW Peterson, LE Badhwar, GD Saganti, PB Dicello, JF AF Cucinotta, FA Schimmerling, W Wilson, JW Peterson, LE Badhwar, GD Saganti, PB Dicello, JF TI Space radiation cancer risks and uncertainties for Mars missions SO RADIATION RESEARCH LA English DT Article ID HEAVY-IONS; MUTATION-INDUCTION; ENERGY PROTONS; CELLS; INACTIVATION; DEPENDENCE; MORTALITY; PARTICLES; EXPOSURE; NEUTRONS AB Projecting cancer risks from exposure to space radiation is highly uncertain because of the absence of data for humans and because of the limited radiobiology data available for estimating late effects from the high-energy and charge (HZE) ions present in the galactic cosmic rays (GCR). Cancer risk projections involve many biological and physical factors, each of which has a differential range of uncertainty due to the lack of data and knowledge. We discuss an uncertainty assessment within the linear-additivity model using the approach of Monte Carlo sampling from subjective error distributions that represent the lack of knowledge in each factor to quantify the overall uncertainty in risk projections. Calculations are performed using the space radiation environment and transport codes for several Mars mission scenarios. This approach leads to estimates of the uncertainties in cancer risk projections of 400-600% for a Mars mission. The uncertainties in the quality factors are dominant. Using safety standards developed for low-Earth orbit, long-term space missions (> 90 days) outside the Earth's magnetic field are currently unacceptable if the confidence levels in risk projections are considered. Because GCR exposures involve multiple particle or delta -ray tracks per cellular array, our results suggest that the shape of the dose response at low dose rates may be an additional uncertainty for estimating space radiation risks. (C) 2001 by Radiation Research Society. C1 NASA, Lyndon B Johnson Space Ctr, Radiat Hlth Off, Houston, TX 77058 USA. NASA Headquarters, Washington, DC 20506 USA. NASA, Langley Res Ctr, Hampton, VA USA. Baylor Coll Med, Dept Med, Houston, TX 77030 USA. Johns Hopkins Med Sch, Baltimore, MD 21287 USA. RP Cucinotta, FA (reprint author), NASA, Lyndon B Johnson Space Ctr, Radiat Hlth Off, Mail Code SA2, Houston, TX 77058 USA. OI Peterson, Leif/0000-0002-1187-0883 NR 37 TC 150 Z9 153 U1 3 U2 21 PU RADIATION RESEARCH SOC PI OAK BROOK PA 820 JORIE BOULEVARD, OAK BROOK, IL 60523 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD NOV PY 2001 VL 156 IS 5 BP 682 EP 688 DI 10.1667/0033-7587(2001)156[0682:SRCRAU]2.0.CO;2 PN 2 PG 7 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 489PB UT WOS:000171999200021 PM 11604093 ER PT J AU De Angelis, G Caldora, M Santaquilani, M Scipione, R Verdecchia, A AF De Angelis, G Caldora, M Santaquilani, M Scipione, R Verdecchia, A TI Health risks from radiation exposure for civilian aviation flight personnel: A study of Italian airline crew members SO RADIATION RESEARCH LA English DT Article ID CANCER INCIDENCE; CABIN ATTENDANTS; PILOTS; MORTALITY; METAANALYSIS; COHORT; FIELDS AB A study of the effects of exposures of civilian aviation flight personnel to atmospheric ionizing radiation (including high-energy neutrons) is being performed. The results of previous studies and of the criteria required for a more satisfactory outcome in future studies are presented, along with a description of the protocol for the Italian national study. A description of the cohort is given in terms of its size, composition and member eligibility. The various ways of determining the exposure and the health status of past and current aircrew members are discussed, and follow-up procedures are described. An overview of the data management and processing philosophy adopted in the Italian study is given with regard to flight routes, radiation dose evaluation along the flight paths, and construction of exposure matrices. Other studies of potential interest are also discussed. The study is still in progress, so the results are preliminary. (C) 2001 by Radiation Research Society. C1 Ist Super Sanita, Epidemiol & Biostat Lab, I-00161 Rome, Italy. NASA, Langley Res Ctr, Hampton, VA 23665 USA. NCI, DCCPS, NIH, Bethesda, MD 20892 USA. RP De Angelis, G (reprint author), Ist Super Sanita, Epidemiol & Biostat Lab, Viale Regina Elena 299,LEB Bldg 19, I-00161 Rome, Italy. RI Santaquilani, Mariano/K-4433-2016 OI Santaquilani, Mariano/0000-0002-9123-654X NR 54 TC 7 Z9 8 U1 0 U2 1 PU RADIATION RESEARCH SOC PI OAK BROOK PA 820 JORIE BOULEVARD, OAK BROOK, IL 60523 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD NOV PY 2001 VL 156 IS 5 BP 689 EP 694 PN 2 PG 6 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 489PB UT WOS:000171999200022 PM 11604094 ER PT J AU Benson, RF Fainberg, J Hess, RA Osherovich, VA Stone, RG AF Benson, RF Fainberg, J Hess, RA Osherovich, VA Stone, RG TI Comment on "Observation of long-duration gyroharmonic resonances: A refutation of the short-duration explanation for interpreting the anomalous URAP sounder spectra observed in the Io torus" SO RADIO SCIENCE LA English DT Editorial Material ID DIFFUSE PLASMA RESONANCES; IONOSPHERIC PLASMA; PHYSICAL NATURE; RADIO; EMISSIONS; INSTABILITY; TURBULENCE; SEQUENCE; SPACE C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Emergent, Largo, MD USA. RP Benson, RF (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Mail Code 692, Greenbelt, MD 20771 USA. NR 29 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD NOV-DEC PY 2001 VL 36 IS 6 BP 1649 EP 1652 DI 10.1029/2001RS002469 PG 4 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 508AT UT WOS:000173065300032 ER PT J AU Higgins, CA Thieman, JR Fung, SF Green, JL Candey, RM AF Higgins, CA Thieman, JR Fung, SF Green, JL Candey, RM TI Simple ray tracing of Galileo-observed hectometric attenuation features SO RADIO SCIENCE LA English DT Article; Proceedings Paper CT Chapman Conference on Space Based Radio Observations at Long Wavelengths CY OCT, 1998 CL PARIS, FRANCE ID RADIO-EMISSION SPECTRUM; MAGNETIC-FIELD; RADIATION; JUPITER AB Observations of persistent structural features within Jovian hectometric (HOM) radio emission have been made with the Galileo spacecraft. Two well-defined sinusoidal-shaped "band" features of reduced emission intensity and occurrence probability exist at all Jovian longitudes and nearly cover the entire spectrum of HOM radio emission from similar to500 kHz to 3000 kHz. These two sinusoidal lanes have a bandwidth of 200-400 kHz and are 180degrees out of phase with one another, suggesting that they are a result of HOM radio emission propagation processes from opposite hemispheres. These features become more apparent when presented as intensity or occurrence probability spectrograms added together over multiple Jovian rotations. Enhancements in the HOM intensity and occurrence are seen along the edges of one of the observed sinusoidal lane features which may indicate caustic surfaces due to refraction along the propagation path. We present some simple ray tracing analyses to show that refraction from density enhancements in the Io torus flux tube may explain some of the observations. Using this simple method, we approximate the density enhancements in the Io flux tube to be 100 cm(-3). C1 NASA, Goddard Space Flight Ctr, Natl Res Council, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Space Sci Data Operat Off, Greenbelt, MD 20771 USA. RP Higgins, CA (reprint author), Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA. RI Candey, Robert/D-4639-2012; Fung, Shing/F-5647-2012 NR 14 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD NOV-DEC PY 2001 VL 36 IS 6 BP 1713 EP 1721 DI 10.1029/2000RS002457 PG 9 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 508AT UT WOS:000173065300040 ER PT J AU Osborne, JJ Harris, IL Roberts, GT Chambers, AR AF Osborne, JJ Harris, IL Roberts, GT Chambers, AR TI Satellite and rocket-borne atomic oxygen sensor techniques SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Review ID GAS MASS-SPECTROMETER; ATMOSPHERE EXPLORER-C; LOW-EARTH-ORBIT; SPACECRAFT MATERIALS; LOWER THERMOSPHERE; SILVER FILMS; REFLECTIVITY CHANGES; OXIDATION; AIRGLOW; SYSTEMS AB Neutral atomic oxygen (AO)-the dominant atmospheric species at typical low Earth orbit altitudes-is responsible for the erosion, or other degradation, of many satellite materials. Therefore, AO has become an important consideration for spacecraft designers and manufacturers. The study of AO is also of interest to atmospheric physicists because it is involved in many of the chemical reactions occurring naturally in the mesosphere and lower thermosphere. Both these groups rely on atmospheric models for computer-based simulation and prediction of atomic oxygen concentrations. Such models require, or are enhanced by, empirical input data-that is, actual measurements of AO number densities. A review is presented of the different measurement techniques that, to date, have been used on satellites and sounding rockets to perform AO studies. Rather than reporting results from every sensor application, this article takes a more general view of the experimental methods, using example devices to highlight their advantages and disadvantages. New or promising equipment, or techniques that could be exploited for performing such measurements, are also described. We attempt some semiquantitative comparison of the techniques, although the most appropriate experimental method for any given flight opportunity depends heavily on the mission conditions and science goals. Our emphasis is on missions where the available mass and power are limited. In these situations the most suitable established device is probably that of the thin film actinometer. If more risk can be assumed then a more promising, but as yet unqualified, method is that of the fiber-optic reflectance sensor. However, since both these devices are nonreusable, it is shown that semiconducting sensors may be better for long duration, mass- and power-limited applications. (C) 2001 American Institute of Physics. C1 VEGA IT GmbH, D-64293 Darmstadt, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Southampton, Sch Engn Sci, Astronaut Res Grp, Southampton SO17 1BJ, Hants, England. RP Univ Southampton, Sch Engn Sci, Astronaut Res Grp, Southampton SO17 1BJ, Hants, England. EM james.osborne@vega.de NR 150 TC 18 Z9 18 U1 3 U2 17 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0034-6748 EI 1089-7623 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD NOV PY 2001 VL 72 IS 11 BP 4025 EP 4041 DI 10.1063/1.1406928 PG 17 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 486AV UT WOS:000171797000001 ER PT J AU Charbonneau, P McIntosh, SW Liu, HL Bogdan, TJ AF Charbonneau, P McIntosh, SW Liu, HL Bogdan, TJ TI Avalanche models for solar flares SO SOLAR PHYSICS LA English DT Article ID SELF-ORGANIZED CRITICALITY; X-RAY-BURSTS; DRIVEN DISSIPATIVE SYSTEMS; CELLULAR-AUTOMATON MODELS; WAITING-TIME DISTRIBUTION; FREQUENCY-DISTRIBUTIONS; ACTIVE-REGION; ENERGY-DISTRIBUTION; STATISTICAL FLARE; QUIET SUN AB This paper is a pedagogical introduction to avalanche models of solar flares, including a comprehensive review of recent modeling efforts and directions. This class of flare model is built on a recent paradigm in statistical physics, known as self-organized criticality. The basic idea is that flares are the result of an `avalanche' of small-scale magnetic reconnection events cascading through a highly stressed coronal magnetic structure, driven to a critical state by random photospheric motions of its magnetic footpoints. Such models thus provide a natural and convenient computational framework to examine Parker's hypothesis of coronal heating by nanoflares. C1 Natl Ctr Atmospher Res, High Altitude Observ, Boulder, CO 80307 USA. NASA, ESA, Dept Space Sci, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Charbonneau, P (reprint author), Natl Ctr Atmospher Res, High Altitude Observ, POB 3000, Boulder, CO 80307 USA. RI Liu, Han-Li/A-9549-2008 OI Liu, Han-Li/0000-0002-6370-0704 NR 99 TC 120 Z9 122 U1 0 U2 6 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD NOV PY 2001 VL 203 IS 2 BP 321 EP 353 DI 10.1023/A:1013301521745 PG 33 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 506NB UT WOS:000172977700008 ER PT J AU Rizzi, SA Bossaert, G AF Rizzi, SA Bossaert, G TI Closed-loop control for sonic fatigue testing systems SO SOUND AND VIBRATION LA English DT Article AB This article documents recent improvements to the acoustic control system of the Thermal Acoustic Fatigue Apparatus (TAFA), a progressive wave tube test facility at the NASA Langley Research Center, Hampton, VA. A brief summary of past acoustic performance is first given to serve as a basis of comparison with the new performance data using a multiple-input, closed-loop, narrow-band controller. Performance data in the form of test section acoustic power spectral densities and coherence are presented for a variety of input spectra including uniform, band-limited random and an expendable launch vehicle payload bay environment. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. M&P Int Inc, Verona, NJ USA. RP Rizzi, SA (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 7 TC 2 Z9 2 U1 0 U2 0 PU ACOUSTICAL PUBL INC PI BAY VILLAGE PA 27101 E OVIATT RD PO BOX 40416, BAY VILLAGE, OH 44140 USA SN 0038-1810 J9 SOUND VIB JI Sound Vib. PD NOV PY 2001 VL 35 IS 11 BP 19 EP 23 PG 5 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 501UR UT WOS:000172704900005 ER PT J AU Sobieszczanski-Sobieski, J Kodiyalam, S Yang, RY AF Sobieszczanski-Sobieski, J Kodiyalam, S Yang, RY TI Optimization of car body under constraints of noise, vibration, and harshness (NVH), and crash SO STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION LA English DT Article DE multidisciplinary design optimization (MDO); high-peformance computing (HPC); crashworthiness; approximations AB A car body structure was optimized for minimum weight under the constraints of noise, vibration, and harshness (NVH), and a crash event, using up to 254 concurrently operating processors. The crash analysis alone, if executed on a single processor and repeated the number of times this optimization required, would have taken 257 days of elapsed computing time. Parallel processing has compressed the elapsed time to one day demonstrating how a multiprocessor machine may be useful in solving engineering tasks that heretofore were regarded as intractable. The optimization procedure transformed the structure initially infeasible to one having its weight reduced and all the constraints satisfied. The experience gained in the reported application indicated it is important to tailor the solution method to the characteristics of the multiprocessor computer architecture and to understand the data handling options offered by that architecture. Another conclusion drawn from this case is that the coarse-grained parallelism whereby an existing code is being replicated over an array of processors should be regarded as an effective way of utilization of multiprocessor machines, immediately available in the interim before solutions are redeveloped from ground up specifically for that class of machines. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. SGI, HPC Applicat Engn & Mkt Dev, Mt View, CA 94043 USA. Ford Motor Co, Vehicle Safety R&D Dept, Dearborn, MI 48121 USA. RP Sobieszczanski-Sobieski, J (reprint author), NASA, Langley Res Ctr, MS 139, Hampton, VA 23665 USA. NR 9 TC 45 Z9 52 U1 3 U2 34 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1615-147X J9 STRUCT MULTIDISCIP O JI Struct. Multidiscip. Optim. PD NOV PY 2001 VL 22 IS 4 BP 295 EP 306 PG 12 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary; Mechanics SC Computer Science; Engineering; Mechanics GA 516ME UT WOS:000173556400004 ER PT J AU Tikhodeev, S Natario, M Makoshi, K Mii, T Ueba, H AF Tikhodeev, S Natario, M Makoshi, K Mii, T Ueba, H TI Contribution to a theory of vibrational scanning tunneling spectroscopy of adsorbates - Nonequilibrium Green's function approach SO SURFACE SCIENCE LA English DT Article; Proceedings Paper CT International Symposium on Surface and Interface: Properties of Different Symmetry Crossing 2000 CY OCT 17-20, 2000 CL NAGOYA, JAPAN DE scanning tunneling spectroscopies; Green's function methods; non-equilibrium thermodynamics and statistical mechanics; vibrations of adsorbed molecules ID METAL TIP; MOLECULE; MICROSCOPY; CO; EXCITATION; CU(100); MODES; STATE AB Formal theory of a phonon-assisted tunneling between a metal surface with an adsorbate and a metal scanning tip through an adsorbate (i.e., vibrational scanning tunneling spectroscopy (STS)) has been presented on the basis of the self-consistent nonequilibrium Keldysh's diagram technique. Within this approach, it is possible to take into account a finite lifetime of vibrational excitation, and the balance between elastic and opening inelastic tunneling channels. The relaxation of the vibrational degrees of freedom is included into the phonon Keldysh-Green function and plays a very important role both in the elastic and the inelastic tunneling through the adsorbate, The tunnel current (the total as well as the inelastic one) is calculated in terms of the one-particle nondiagonal substrate-adsorbate Keldysh-Green's function supplemented with the vibrational lifetime and filling factors of adsorbate orbital and phonons. The general expression of the inelastic tunnel current and conductance via the excitation of phonons is also presented in terms of the phonon occupation number and the phonon damping function in the stationary condition. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Toyama Univ, Dept Elect, Toyama 930, Japan. Russian Acad Sci, Inst Gen Phys, Moscow, Russia. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Himeji Inst Technol, Hyogo, Japan. RP Ueba, H (reprint author), Toyama Univ, Dept Elect, Toyama 930, Japan. RI Tikhodeev, Sergei/A-5452-2016 OI Tikhodeev, Sergei/0000-0001-5940-055X NR 21 TC 40 Z9 40 U1 1 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD NOV 1 PY 2001 VL 493 IS 1-3 BP 63 EP 70 DI 10.1016/S0039-6028(01)01190-6 PG 8 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 486GL UT WOS:000171810000010 ER PT J AU Makoshi, K Mingo, N Mii, T Ueba, H Tikhodeev, S AF Makoshi, K Mingo, N Mii, T Ueba, H Tikhodeev, S TI Theory of vibrational excitations of adsorbates by the scanning tunneling spectroscopy SO SURFACE SCIENCE LA English DT Article; Proceedings Paper CT International Symposium on Surface and Interface: Properties of Different Symmetry Crossing 2000 CY OCT 17-20, 2000 CL NAGOYA, JAPAN DE scanning tunneling spectroscopies; vibrations of adsorbed molecules; scanning tunneling microscopy; Green's function methods ID CU(100); CO; MOLECULE; MODES AB A theory to obtain "inelastic" components of electric conductance due to the scattering by adsorbate vibrations is presented. The method is applied to C2H2/Cu(001) and an interference effect is found through surface localized electronic states which become able to carry current with electron-vibration coupling. A preliminary account for CO/Cu(001) is also given as well as the relation between the deexcitation rate of vibrational modes due to electron-hole pair excitations and inelastic components of conductance. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Himeji Inst Technol, Fac Sci, Kamigori 6781297, Japan. Japan Synchrotron Radiat Res Ctr, Mikazuki 6795148, Japan. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Dept Elect, Toyama 9300887, Japan. Russian Acad Sci, Inst Gen Phys, Moscow 119991, Russia. RP Makoshi, K (reprint author), Himeji Inst Technol, Fac Sci, Kamigori 6781297, Japan. RI Tikhodeev, Sergei/A-5452-2016 OI Tikhodeev, Sergei/0000-0001-5940-055X NR 10 TC 3 Z9 3 U1 1 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD NOV 1 PY 2001 VL 493 IS 1-3 BP 71 EP 77 DI 10.1016/S0039-6028(01)01191-8 PG 7 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA 486GL UT WOS:000171810000011 ER PT J AU Barrie, LA Yi, Y Leaitch, WR Lohmann, U Kasibhatla, P Roelofs, GJ Wilson, J McGovern, F Benkovitz, C Melieres, MA Law, K Prospero, J Kritz, M Bergmann, D Bridgeman, C Chin, M Christensen, J Easter, R Feichter, J Land, C Jeuken, A Kjellstrom, E Koch, D Rasch, P AF Barrie, LA Yi, Y Leaitch, WR Lohmann, U Kasibhatla, P Roelofs, GJ Wilson, J McGovern, F Benkovitz, C Melieres, MA Law, K Prospero, J Kritz, M Bergmann, D Bridgeman, C Chin, M Christensen, J Easter, R Feichter, J Land, C Jeuken, A Kjellstrom, E Koch, D Rasch, P TI A comparison of large-scale atmospheric sulphate aerosol models (COSAM): overview and highlights SO TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY LA English DT Article ID GLOBAL SULFATE DISTRIBUTION; GENERAL-CIRCULATION MODEL; SULFUR CYCLE; SIMULATION; AIR; PHOTOCHEMISTRY; EMISSIONS; TRANSPORT AB The comparison of large-scale sulphate aerosol models study (COSAM) compared the performance of atmospheric models with each other and observations. It involved: (i) design of a standard model experiment for the world wide web, (ii) 10 model simulations of the cycles of sulphur and Rn-222 Pb-210 conforming to the experimental design, (iii) assemblage of the best available observations of atmospheric SO4=, SO2 and MSA and (iv) a workshop in Halifax, Canada to analyze model performance and future model development needs. The analysis presented in this paper and two companion papers by Roelofs, and Lohmann and co-workers examines the variance between models and observations. discusses the sources of that variance and suggests ways to improve models. Variations between models in the export of SOx from Europe or North America are not sufficient to explain an order of magnitude variation in spatial distributions of SOx downwind in the northern hemisphere. On average, models predicted surface level seasonal mean SO4= aerosol mixing ratios better (most within 20%) than SO2 mixing ratios (over-prediction by factors of 2 or more). Results suggest that vertical mixing from the planetary boundary layer into the free troposphere in source regions is a major source of uncertainty in predicting the global distribution of SO aerosols in climate models today. For improvement. it is essential that globally coordinated research efforts continue to address emissions of all atmospheric species that affect the distribution and optical properties of ambient aerosols in models and that a global network of observations be established that will ultimately produce a world aerosol chemistry climatology. C1 Pacific NW Natl Lab, Fundamental Sci Div, Richland, WA 99352 USA. E Giant Sci & Technol Inc, Toronto, ON M2J 4N3, Canada. Environm Canada, Climate & Atmospher Sci Directorate, Toronto, ON M3H 5T4, Canada. Dalhousie Univ, Dept Phys, Atmospher Sci Program, Halifax, NS B3H 3J5, Canada. Duke Univ, Nicholas Sch Environm, Durham, NC USA. Univ Utrecht, IMAU, Utrecht, Netherlands. European Commiss Environm Inst, Ispra, Italy. Univ Coll Dublin, Dept Expt Phys, Dublin 2, Ireland. Brookhaven Natl Lab, Dept Environm Sci, Upton, NY 11973 USA. Lab Glaciol & Geophys Environm, Grenoble, France. Univ Cambridge, Dept Chem, Ctr Atmospher Sci, Cambridge CB2 1EW, England. Univ Miami, Miami, FL 33152 USA. SUNY Albany, Atmospher Sci Res Ctr, Albany, NY 12222 USA. Univ Calif Lawrence Livermore Natl Lab, Div Atmospher Sci, Livermore, CA USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Environm Res Inst, Roskilde, Denmark. Max Planck Inst Meteorol, Hamburg, Germany. Royal Netherlands Meteorol Inst, KNMI, NL-3730 AE De Bilt, Netherlands. Univ Stockholm, Dept Meteorol, S-10691 Stockholm, Sweden. Goddard Inst Space Studies, Dept Geol & Geophys, New Haven, CT USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. RP Barrie, LA (reprint author), Pacific NW Natl Lab, Fundamental Sci Div, POB 999, Richland, WA 99352 USA. RI Kasibhatla, Prasad/A-2574-2010; Bergmann, Daniel/F-9801-2011; Christensen, Jesper /E-9524-2011; Chin, Mian/J-8354-2012; Lohmann, Ulrike/B-6153-2009; OI Bergmann, Daniel/0000-0003-4357-6301; Christensen, Jesper /0000-0002-6741-5839; Lohmann, Ulrike/0000-0001-8885-3785; Prospero, Joseph/0000-0003-3608-6160; Kasibhatla, Prasad/0000-0003-3562-3737; Kjellstrom, Erik/0000-0002-6495-1038 NR 31 TC 78 Z9 81 U1 1 U2 16 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6509 J9 TELLUS B JI Tellus Ser. B-Chem. Phys. Meteorol. PD NOV PY 2001 VL 53 IS 5 BP 615 EP 645 DI 10.1034/j.1600-0889.2001.530507.x PG 31 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 492ZN UT WOS:000172197600006 ER PT J AU Lohmann, U Leaitch, WR Barrie, L Law, K Yi, Y Bergmann, D Bridgeman, C Chin, M Christensen, J Easter, R Feichter, J Jeuken, A Kjellstrom, E Koch, D Rasch, P Roelofs, GJ AF Lohmann, U Leaitch, WR Barrie, L Law, K Yi, Y Bergmann, D Bridgeman, C Chin, M Christensen, J Easter, R Feichter, J Jeuken, A Kjellstrom, E Koch, D Rasch, P Roelofs, GJ TI Vertical distributions of sulfur species simulated by large scale atmospheric models in COSAM: Comparison with observations SO TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY LA English DT Article ID GENERAL-CIRCULATION MODEL; GLOBAL CLIMATE MODEL; DRY DEPOSITION; CYCLE; TRANSPORT; VALIDATION; CHEMISTRY; CLOUDS; OXIDES; GASES AB A comparison of large-scale models simulating atmospheric sulfate aerosols (COSAM) was conducted to increase Our understanding of global distributions of sulfate aerosols and precursors. Earlier model comparisons focused on wet deposition measurements and sulfate aerosol concentrations in source regions at the surface. They found that different models simulated the Observed Sulfate surface concentrations mostly within a factor of two. but that the simulated column burdens and vertical profiles were very different amongst different models. In the COSAM exercise. one aspect is the comparison Of sulfate aerosol and precursor gases above the surface. Vertical profiles of SO2, SO42-, oxidants and cloud properties were measured by aircraft during the North Atlantic Regional Experiment (NARE) experiment in August September 1993 off the coast of Nova Scotia and during the Second Eulerian Model Evaluation Field Study (EMEFSII), in central Ontario in March April 1990. While no single model stands Out as being best or worst, the general tendency is that those models simulating the full oxidant chemistry tend to agree best with observations although differences in transport and treatment Of Clouds are important as well. C1 Dalhousie Univ, Dept Phys, Atmospher Sci Program, Halifax, NS B3H 3J5, Canada. Meteorol Serv Canada, Downsview, ON, Canada. Pacific NW Natl Lab, Richland, WA USA. Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England. Lawrence Livermore Natl Lab, Div Atmospher Sci, Livermore, CA USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Environm Res Inst, Roskilde, Denmark. Max Planck Inst Meteorol, Hamburg, Germany. Royal Netherlands Meteorol Inst, KNMI, NL-3730 AE De Bilt, Netherlands. Stockholm Univ, S-10691 Stockholm, Sweden. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Univ Utrecht, Inst Marine & Atmospher Res, Utrecht IMAU, Utrecht, Netherlands. RP Lohmann, U (reprint author), Dalhousie Univ, Dept Phys, Atmospher Sci Program, Halifax, NS B3H 3J5, Canada. RI Bergmann, Daniel/F-9801-2011; Christensen, Jesper /E-9524-2011; Chin, Mian/J-8354-2012; Lohmann, Ulrike/B-6153-2009; OI Bergmann, Daniel/0000-0003-4357-6301; Christensen, Jesper /0000-0002-6741-5839; Lohmann, Ulrike/0000-0001-8885-3785; Kjellstrom, Erik/0000-0002-6495-1038 NR 32 TC 28 Z9 29 U1 0 U2 3 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6509 J9 TELLUS B JI Tellus Ser. B-Chem. Phys. Meteorol. PD NOV PY 2001 VL 53 IS 5 BP 646 EP 672 DI 10.1034/j.1600-0889.2001.530508.x PG 27 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 492ZN UT WOS:000172197600007 ER PT J AU Roelofs, GJ Kasibhatla, P Barrie, L Bergmann, D Bridgeman, C Chin, M Christensen, J Easter, R Feichter, J Jeuken, A Kjellstrom, E Koch, D Land, C Lohmann, U Rasch, P AF Roelofs, GJ Kasibhatla, P Barrie, L Bergmann, D Bridgeman, C Chin, M Christensen, J Easter, R Feichter, J Jeuken, A Kjellstrom, E Koch, D Land, C Lohmann, U Rasch, P TI Analysis of regional budgets of sulfur species modeled for the COSAM exercise SO TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY LA English DT Article ID GENERAL-CIRCULATION MODEL; SULFATE AEROSOLS; CLIMATE MODEL; CYCLE; SIMULATION; TRANSPORT; ALBEDO; PHOTOCHEMISTRY; SENSITIVITY; TROPOSPHERE AB The COSAM intercomparison exercise (comparison of large-scale sulfur models) was organized to compare and evaluate the performance of global sulfur cycle models. Eleven models participated. and from these models the simulated surface concentrations, vertical profiles and budget terms were submitted. This study focuses on simulated budget terms for the sources and sinks of SO2 and sulfate in three polluted regions in the Northern Hemisphere. i.e., eastern North America, Europe, and Southeast Asia. Qualitatively, features of the sulfur cycle are modeled quite consistently between models, such as the relative importance of dry deposition as a removal mechanism for SO2, the importance of aqueous phase oxidation over gas phase oxidation for SO2, and the importance of wet over dry deposition for removal of sulfate aerosol. Quantitatively, however, models may show large differences. especially for cloud-related processes, i.e., aqueous phase oxidation Of SO2 and sulfate wet deposition, In some cases a specific behavior can be related to the treatment of oxidants for aqueous phase SO2 oxidation, or the vertical resolution applied in models. Generally, however, the differences between models appear to be related to simulated cloud (micro-)physics and distributions, whereas differences in vertical transport efficiencies related to convection play an additional role. The estimated sulfur column burdens. lifetimes and export budgets vary between models by about a factor of 2 or 3. It can be expected that uncertainties in related effects which are derived from global sulfur model calculations. such as direct and indirect climate forcing estimates by sulfate aerosol, are at least of similar magnitude. C1 Univ Utrecht, Inst Marine & Atmospher Res Utrecht, IMAU, Utrecht, Netherlands. Duke Univ, Nicholas Sch Environm, Durham, NC USA. Pacific NW Natl Lab, Richland, WA USA. Lawrence Livermore Natl Lab, Div Atmospher Sci, Livermore, CA USA. Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Environm Res Inst, Roskilde, Denmark. Pacific NW Natl Lab, Richland, WA USA. Max Planck Inst Meteorol, Hamburg, Germany. Royal Netherlands Meteorol Inst, KNMI, NL-3730 AE De Bilt, Netherlands. Stockholm Univ, Dept Meteorol, S-10691 Stockholm, Sweden. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Dalhousie Univ, Atmospher Sci Program, Halifax, NS, Canada. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. RP Roelofs, GJ (reprint author), Univ Utrecht, Inst Marine & Atmospher Res Utrecht, IMAU, Utrecht, Netherlands. RI Kasibhatla, Prasad/A-2574-2010; Bergmann, Daniel/F-9801-2011; Christensen, Jesper /E-9524-2011; Chin, Mian/J-8354-2012; Lohmann, Ulrike/B-6153-2009; OI Bergmann, Daniel/0000-0003-4357-6301; Christensen, Jesper /0000-0002-6741-5839; Lohmann, Ulrike/0000-0001-8885-3785; Kasibhatla, Prasad/0000-0003-3562-3737; Kjellstrom, Erik/0000-0002-6495-1038 NR 31 TC 35 Z9 36 U1 0 U2 4 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6509 J9 TELLUS B JI Tellus Ser. B-Chem. Phys. Meteorol. PD NOV PY 2001 VL 53 IS 5 BP 673 EP 694 DI 10.1034/j.1600-0889.2001.530509.x PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 492ZN UT WOS:000172197600008 ER PT J AU Lesuer, DR Syn, CK Whittenberger, JD Carsi, M Ruano, OA Sherby, OD AF Lesuer, DR Syn, CK Whittenberger, JD Carsi, M Ruano, OA Sherby, OD TI Creep behavior of Fe-C alloys at high temperatures and high strain rates SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article DE creep; steels; stacking fault energy; diffusivity ID ULTRAHIGH-CARBON STEELS; MICROSTRUCTURE; CLIMB AB The creep behavior of Fe-C alloys (1-1.8%C) has been studied at high temperatures (0.7-0.9T(m)) and high strain rates (1-100 s(-1)). The dominant deformation resistance has been found to be climb-controlled dislocation creep and thus the creep rates are a function of elastic modulus, lattice diffusivity and stacking fault energy. The self-diffusion coefficient of iron in austenite was found to be solely a function of T-m/T and to vary as D = 6.8 x 10(-6) exp( - 17T(m)/T) m(2) s(-1). The Fe-C alloys were observed to have a high stacking fault energy which was unaffected by carbon and manganese. The stacking fault energy was observed to decrease with increasing concentrations of silicon, aluminum and chromium. At high stresses, deviation from power law behavior was accounted for by considering the contributions to diffusivity by dislocation pipe diffusion. The results have been used to develop a rate equation for these steels of varying composition that depends on only three material characteristics - alloy melting temperature, elastic modulus and stacking fault energy. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. Ctr Nacl Invest Met, Dept Met Phys, Madrid 28040, Spain. Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 USA. RP Lesuer, DR (reprint author), Lawrence Livermore Natl Lab, POB 808,L-342, Livermore, CA 94551 USA. RI Ruano, Oscar/H-1835-2015; OI Ruano, Oscar/0000-0001-6368-986X; carsi, manuel/0000-0001-8068-5385 NR 23 TC 19 Z9 20 U1 1 U2 3 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD OCT 31 PY 2001 VL 317 IS 1-2 SI SI BP 101 EP 107 DI 10.1016/S0921-5093(01)01167-4 PG 7 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 477ED UT WOS:000171269400017 ER PT J AU Suo, Y Stoev, K Garoff, S Rame, E AF Suo, Y Stoev, K Garoff, S Rame, E TI Hydrodynamics and contact angle relaxation during unsteady spreading SO LANGMUIR LA English DT Article ID BOUNDARY-CONDITIONS; LINE; HYSTERESIS; PLATE; INTERFACE; DYNAMICS; SURFACES; DROPS AB We have studied the unsteady spreading of a liquid on a solid surface by observing the liquid-air meniscus shape and analyzing it with the hydrodynamic theory for Stokes' flow. The unsteady spreading process exhibits both quasi-steady and unsteady regimes. The unsteadiness in our moderately high viscosity system arises from temporal relaxation of the contact angle rather than inertial effects or momentum diffusion. The quasi-steady regime can be accurately described by a model that ascribes a steady-state flow near the contact line. "Spontaneous" spreading, i.e., spreading to final state of zero contact line speed, is recognized as a special case of the general unsteady spreading process with the commonly used power laws for spreading occurring only under special conditions. C1 Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. Carnegie Mellon Univ, Ctr Complex Fluids Engn, Pittsburgh, PA 15213 USA. NASA, Glenn Res Ctr, Natl Ctr Micrograv Res, Cleveland, OH 44135 USA. RP Suo, Y (reprint author), Carnegie Mellon Univ, Dept Phys, Pittsburgh, PA 15213 USA. RI Garoff, Stephen/P-7629-2014 OI Garoff, Stephen/0000-0001-8148-8535 NR 23 TC 9 Z9 9 U1 2 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0743-7463 J9 LANGMUIR JI Langmuir PD OCT 30 PY 2001 VL 17 IS 22 BP 6988 EP 6994 DI 10.1021/la0104572 PG 7 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 486LA UT WOS:000171818200037 ER PT J AU Hansen, J Ruedy, R Sato, M Imhoff, M Lawrence, W Easterling, D Peterson, T Karl, T AF Hansen, J Ruedy, R Sato, M Imhoff, M Lawrence, W Easterling, D Peterson, T Karl, T TI A closer look at United States and global surface temperature change SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLIMATOLOGICAL TIME-SERIES; CLIMATE-CHANGE; NETWORK; TRENDS; SIMULATION; SATELLITE; FORCINGS; MINIMUM; MAXIMUM; MODEL AB We compare the United States and global surface air temperature changes of the past century using the current Goddard Institute for Space Studies (GISS) analysis and the U.S. Historical Climatology Network (USHCN) record [Karl et al., 1990]. Changes in the GISS analysis subsequent to the documentation by Hansen et al. [1999] are as follows: (1) incorporation of corrections for time-of-observation bias and station history adjustments in the United States based on Easterling et al. [ 1996a], (2) reclassification of rural, small-town, and urban stations in the United States, southern Canada, and northern Mexico based on satellite measurements of night light intensity [Imhoff et al., 1997], and (3) a more flexible urban adjustment than that employed by Hansen et al. [1999], including reliance: on only unlit stations in the United States and rural stations in the rest of the world for determining long-term trends. We find evidence of local human effects ("urban warming") even in suburban and small-town surface air temperature records, but the effect is modest in magnitude and conceivably could be an artifact of inhomogeneities in the station records. We suggest further studies, including more complete satellite night light analyses. which may clarify the potential urban effect. There are inherent uncertainties in the long-term temperature change at least of the order of 0.1 degreesC for both the U.S. mean and the global mean. Nevertheless, it is clear that the post- 1930s cooling was much larger in the United States than in the global mean. The U.S. mean temperature has now reached a level comparable to that of the 1930s, while the global temperature is now far above the levels earlier in the century. The successive periods of global warming (1900-1940), cooling (1940-1965), and warming (1965-2000) in the 20th century show distinctive patterns of temperature change suggestive of roles for both climate forcings and dynamical variability. The U.S. was warm in 2000 but cooler than the warmest years in the 1930s and 1990s. Global temperature was moderately high in 2000 despite a lingering La Nina in the Pacific Ocean. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. NASA, Goddard Space Flight Ctr, New York, NY 10025 USA. NOAA, Natl Climat Data Ctr, Asheville, NC 28801 USA. RP Hansen, J (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM hansen@giss.nasa.gov NR 40 TC 330 Z9 362 U1 3 U2 58 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 27 PY 2001 VL 106 IS D20 BP 23947 EP 23963 DI 10.1029/2001JD000354 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 489CG UT WOS:000171974000001 ER PT J AU Kiedron, P Michalsky, J Schmid, B Slater, D Berndt, J Harrison, L Racette, P Westwater, E Han, Y AF Kiedron, P Michalsky, J Schmid, B Slater, D Berndt, J Harrison, L Racette, P Westwater, E Han, Y TI A robust retrieval of water vapor column in dry Arctic conditions using the rotating shadowband spectroradiometer SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SOLAR TRANSMITTANCE MEASUREMENTS; ABSORPTION; CLOUD; RADIOMETER; RADIATION; DATABASE AB A method to retrieve water vapor column using the 940-nm water vapor absorption band in dry Arctic conditions is presented. The retrievals with this method are stable with respect to uncertainties in instrument radiometric calibration, air pressure, solar source function, and aerosols. The water vapor column was retrieved with this method using spectra obtained with the rotating shadowband spectroradiometer (RSS) that was deployed during an intensive observation period near Barrow, Alaska, in March 1999. A line-by-line radiative transfer model was used to compute water vapor transmittance. The retrievals with this method are compared with retrievals obtained from three independent measurements with microwave radiometers. All four measurements show the same pattern of temporal variations. The RSS results agree most closely with retrievals obtained with the millimeter-wave imaging radiometer (MIR) at its 183 GHz 7 double-side band channel. Their correlation over a period of 7 days when water vapor column varied between 0.75 mm and 3.6 mm (according to RSS) is 0.968 with MIR readings 0.12 mm higher on average. C1 SUNY Albany, ASRC, Albany, NY 12203 USA. Univ Colorado, CIRES, Boulder, CO 80305 USA. NASA, Goddard Space Flight Ctr, Microwave Instrument Technol Branch, Greenbelt, MD 20771 USA. NASA, Ames Res Ctr, Bay Area Environm Res Inst, Moffett Field, CA 94035 USA. RP Kiedron, P (reprint author), SUNY Albany, ASRC, 251 Fuller Rd, Albany, NY 12203 USA. EM kiedron@asrc.cestm.albany.edu; bschmid@mail.arc.nasa.gov; donald.slater@pnl.gov; per@priam.gsfc.nasa.gov; Ed.R.Westwater@noaa.gov RI Han, Yong/F-5590-2010 OI Han, Yong/0000-0002-0183-7270 NR 29 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 27 PY 2001 VL 106 IS D20 BP 24007 EP 24016 DI 10.1029/2000JD000130 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 489CG UT WOS:000171974000006 ER PT J AU Garand, L Turner, DS Larocque, M Bates, J Boukabara, S Brunel, P Chevallier, F Deblonde, G Engelen, R Hollingshead, M Jackson, D Jedlovec, G Joiner, J Kleespies, T McKague, DS McMillin, L Moncet, JL Pardo, JR Rayer, PJ Salathe, E Saunders, R Scott, NA Van Delst, P Woolf, H AF Garand, L Turner, DS Larocque, M Bates, J Boukabara, S Brunel, P Chevallier, F Deblonde, G Engelen, R Hollingshead, M Jackson, D Jedlovec, G Joiner, J Kleespies, T McKague, DS McMillin, L Moncet, JL Pardo, JR Rayer, PJ Salathe, E Saunders, R Scott, NA Van Delst, P Woolf, H TI Radiance and Jacobian intercomparison of radiative transfer models applied to HIRS and AMSU channels SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID WATER-VAPOR; ATMOSPHERIC TRANSMITTANCE; INFRARED RADIANCES; ABSORBING GAS; COOLING RATES; ASSIMILATION; ABSORPTION; BAND; PARAMETERS; FLUXES AB The goals of this study are the evaluation of current fast radiative transfer models (RTMs) and line-by-line (LBL) models. The intercomparison focuses on the modeling of 11 representative sounding channels routinely used at numerical weather prediction centers: 7 HIRS (High-resolution Infrared Sounder) and 4 AMSU (advanced microwave sounding unit) channels. Interest in this topic was evident by the participation of 24 scientists from 16 institutions. An ensemble of 42 diverse atmospheres was used and results compiled for 19 infrared models and 10 microwave models, including several LBL RTMs. For the first time, not only radiances but also Jacobians (of temperature, water vapor, and ozone) were compared to various LBL models for many,channels. In the infrared, LBL models typically agree to within 0.05-0.15 K (standard deviation) in terms of top-of-the-atmosphere brightness temperature (BT) Individual differences up to 0.5 K still exist, systematic in some channels, and linked to the type of atmosphere in others. The best fast models emulate LBL BTs to within 0.25 K, but no model achieves this desirable level of success for all channels. The ozone modeling is particularly challenging. In the microwave, fast models generally do quite well against the LBL model to which they were tuned. However, significant differences were noted among LBL models. Extending the intercomparison to the Jacobians proved very useful in detecting subtle or more obvious modeling errors. In addition, total and single gas optical depths were calculated, which provided additional insight on the nature of differences. C1 Meteorol Serv Canada, Dorval, PQ H9P 1J3, Canada. NOAA, ERL, Boulder, CO 80303 USA. Meteorol Serv Canada, Downsview, ON M3H 5T4, Canada. Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. Meteo France, Lannion, France. ECMWF, Reading, Berks, England. European Ctr Medium Range Weather Forecasts, Reading, Berks, England. Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. Raytheon Co, Aurora, CO 80011 USA. NASA, MSFC, Huntsville, AL 35805 USA. NASA, DAO, Greenbelt, MD 20771 USA. NOAA, NESDIS, Camp Springs, CA 91125 USA. CALTECH, Pasadena, CA 91125 USA. Meteorol Off, Bracknell RB12 2SZ, Berks, England. Univ Washington, Seattle, WA 98195 USA. CNRS, Meteorol Dynam Lab, Palaiseau, France. Univ Wisconsin, Madison, WI 53706 USA. RP Garand, L (reprint author), Meteorol Serv Canada, 2121 Trans Canada Highway, Dorval, PQ H9P 1J3, Canada. EM louis.garand@ec.gc.ca RI Boukabara, Sid Ahmed/F-5577-2010; Kleespies, Thomas/F-5598-2010; Joiner, Joanna/D-6264-2012; McKague, Darren/J-2590-2012; Bates, John/D-1012-2009; Jackson, Darren/D-5506-2015; Chevallier, Frederic/E-9608-2016 OI Boukabara, Sid Ahmed/0000-0002-1857-3806; McKague, Darren/0000-0003-0297-0388; Bates, John/0000-0002-8124-0406; Jackson, Darren/0000-0001-5211-7866; Chevallier, Frederic/0000-0002-4327-3813 NR 39 TC 70 Z9 74 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 27 PY 2001 VL 106 IS D20 BP 24017 EP 24031 DI 10.1029/2000JD000184 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 489CG UT WOS:000171974000007 ER PT J AU Ushio, T Heckman, SJ Boccippio, DJ Christian, HJ Kawasaki, ZI AF Ushio, T Heckman, SJ Boccippio, DJ Christian, HJ Kawasaki, ZI TI A survey of thunderstorm flash rates compared to cloud top height using TRMM satellite data SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GLOBAL LIGHTNING DISTRIBUTIONS; RADAR AB The relationship between cloud height and lightning activity is examined using data from the Tropical Rainfall Measuring Mission (TRMM) satellite. Coincident data from the precipitation radar (PR) and Lightning Imaging Sensor aboard the TRMM satellite are used to examine whether lightning flash rate is proportional to the fifth power of cloud top height. This study is unique in that (1) the relationship between instantaneous rather than maximum storm height and flash rate is obtained and (2) relatively unbiased full data sets for different locations and seasons over the globe are used. The relationship between thunderstorm height and flash rate is nonlinear with large variance. The overall trend shows that flash rate increases exponentially with storm height. Some tall thunderstorms do not have large flash rates, but the reverse situation never occurs. The fifth power dependency that is derived from scaling laws is not inconsistent with, but not necessarily required by, the observed data. C1 NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Natl Space Sci & Technol Ctr, Huntsville, AL 35805 USA. Univ Space Res Assoc, Global Hydrol & Climate Ctr, Natl Space Sci & Technol Ctr, Huntsville, AL 35805 USA. Osaka Univ, Dept Commun Engn, Suita, Osaka 5650871, Japan. RP Ushio, T (reprint author), Osaka Prefecture Univ, Aerosp Res Dept, 1-1 Gakuencho, Sakai, Osaka 5998531, Japan. EM ushio@aero.osakafu-u.ac.jp; stan@stanheckman.com; dennis.boccippio@msfc.nasa.gov RI Ushio, Tomoo/G-6915-2011; PMM, JAXA/K-8537-2016 NR 16 TC 53 Z9 57 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 27 PY 2001 VL 106 IS D20 BP 24089 EP 24095 DI 10.1029/2001JD900233 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 489CG UT WOS:000171974000013 ER PT J AU Rosi, M Bauschlicher, CW AF Rosi, M Bauschlicher, CW TI Using hydrogen and chlorine on Si(111) to store data, an improved model SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GEOMETRY OPTIMIZATION; MOLECULAR MECHANICS AB Our previous suggestion for atomic data storage is tested using an improved model. Namely, a carbon nanotube is added to the tip and size of the cluster model used to simulate the surface is expanded. The ONIOM approach makes these tests possible. The tip-surface distances and interaction energies are found to be relatively insensitive to the model used. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Perugia, Dept Chem, CNR, Ctr High Performance Comp Mol Sci, I-06100 Perugia, Italy. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. RI Rosi, Marzio/L-5748-2015 OI Rosi, Marzio/0000-0002-1264-3877 NR 14 TC 5 Z9 5 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD OCT 26 PY 2001 VL 347 IS 4-6 BP 291 EP 296 DI 10.1016/S0009-2614(01)01060-0 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 486PA UT WOS:000171825100003 ER PT J AU Ricca, A Bauschlicher, CW Rosi, M AF Ricca, A Bauschlicher, CW Rosi, M TI Mechanisms for the incorporation of a nitrogen atom into polycyclic aromatic hydrocarbon cations SO CHEMICAL PHYSICS LETTERS LA English DT Article ID INFRARED-SPECTRA; ACETYLENE; FLAMES AB The growth of a second aromatic ring, for cationic species containing a nitrogen atom, is studied at the B3LYP/6-31G* level of theory. For the most favorable processes, the maximum barrier is about 15 kcal/mol and is associated with the breaking of an aromatic C-H bond. This barrier is similar in magnitude to that found for the pure hydrocarbon case. Thus, the inclusion of nitrogen into polycyclic aromatic hydrocarbon (PAH) rings seems favorable if HCN is present during the ring growth processes. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Perugia, Dept Chem, CNR, Ctr High Performance Comp Mol Sci, I-06123 Perugia, Italy. RP Ricca, A (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. RI Rosi, Marzio/L-5748-2015 OI Rosi, Marzio/0000-0002-1264-3877 NR 22 TC 14 Z9 14 U1 1 U2 12 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD OCT 26 PY 2001 VL 347 IS 4-6 BP 473 EP 480 DI 10.1016/S0009-2614(01)01061-2 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 486PA UT WOS:000171825100031 ER PT J AU Albee, AL Arvidson, RE Palluconi, F Thorpe, T AF Albee, AL Arvidson, RE Palluconi, F Thorpe, T TI Overview of the Mars Global Surveyor mission SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID THERMAL EMISSION SPECTROMETER; ORBITER-LASER-ALTIMETER; MARTIAN SURFACE; MGS-TES; OBSERVER; TEMPERATURES; AEROBRAKING; TOPOGRAPHY; ATMOSPHERE; OCEANS AB The Mars Global Surveyor spacecraft was placed into Mars orbit on September 11, 1997, and by March 9, 1999, had slowly circularized through aerobraking to a Sun-synchronous, near-polar orbit with an average altitude of 378 km. The science payload includes the Mars Orbiter Camera, Mars Orbiter Laser Altimeter, Thermal Emission Spectrometer, Ultrastable Oscillator (for Radio Science experiments), and Magnetometer/Electron Reflectometer package. In addition, the spacecraft accelerometers and horizon sensors were used to study atmospheric dynamics during aerobraking. Observations are processed to standard products by the instrument teams and released as documented archive volumes on 6-month centers by the Planetary Data System. Significant results have been obtained from observations of the interior, surface, and atmosphere. For example, Mars does not now have an active magnetic field, although strong remanent magnetization features exist in the ancient crust. These results imply that an internal dynamo ceased operation early in geologic time. Altimetry and gravity data indicate that the crust is thickest under the south pole, thinning northward from the cratered terrain to the northern plains. Analysis of altimetry data demonstrates that Mars is "egg-shaped" with gravitational equipotential contours that show that channel systems in the southern highlands drained to the north, largely to the Chryse trough. A closed contour in the northern plains is consistent with the existence of a great northern ocean. Emission spectra of low-albedo regions show that basaltic rocks dominate spectral signatures on the southern highlands, whereas basaltic andesites dominate the northern lowlands. The bright regions show nondiagnostic spectra, similar to that of dust in the atmosphere. Signatures of aqueous minerals (e.g., clays, carbonates, and sulfates) are noticeably absent from the emission spectra. High spatial resolution images show that the surface has been extensively modified by wind and that layering is nearly ubiquitous, implying that a complex history of events is recorded in surface and near-surface materials. Altimetry data imply that both permanent caps are composed of water ice and dust, with seasonal covers of carbon dioxide frost. Finally, the altimetry data, coupled with thousands of atmospheric profiles, are providing new boundary conditions and dynamic controls for the generation and testing of more realistic dynamic models of the global circulation of the atmosphere. C1 CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Washington Univ, Dept Earth & Planetary Sci, McDonnell Ctr Space Sci, St Louis, MO 63130 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Albee, AL (reprint author), CALTECH, Div Geol & Planetary Sci, Mail Code 170-25, Pasadena, CA 91125 USA. NR 48 TC 87 Z9 88 U1 2 U2 14 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23291 EP 23316 DI 10.1029/2000JE001306 PG 26 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900009 ER PT J AU Haberle, RM McKay, CP Schaeffer, J Cabrol, NA Grin, EA Zent, AP Quinn, R AF Haberle, RM McKay, CP Schaeffer, J Cabrol, NA Grin, EA Zent, AP Quinn, R TI On the possibility of liquid water on present-day Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID AEROBRAKING; SIMULATIONS; EVOLUTION; BEHAVIOR; CYCLE; VAPOR AB Using a validated general circulation model, we determine where and for how long the surface pressure and surface temperature on Mars meet the minimum requirements for the existence of liquid water in the present climate system: pressures and temperatures above the triple point of water but below the boiling point. We find that for pure liquid water, there are five "favorable" regions where these requirements are satisfied: between 0 degrees and 30 degreesN in the plains of Amazonis, Arabia, and Elysium; and in the Southern Hemisphere impact basins of Hellas and Argyre. The combined area of these regions represents 29% of the planet's surface area. In the Amazonis region these requirements are satisfied for a total integrated time of 37 sols each Martian year. In the Hellas basin the number of degree days above zero is 70, which is well above those experienced in the dry valley lake region of Antarctica. These regions are remarkably well correlated with the location of Amazonian paleolakes mapped by Cabrol and Grin [2000] but are poorly correlated with the seepage gullies found by Malin and Edgett [2000]. In both instances, obliquity variations may play a role. For brine solutions the favorable regions expand and could potentially include most of the planet for highly concentrated solutions. Whether liquid water ever forms in these regions depends on the availability of ice and heat and on the evaporation rate. The latter is poorly understood for low-pressure CO2 environments but is likely to be so high that melting occurs rarely, if at all. However, even rare events of liquid water formation would be significant since they would dominate the chemistry of the soil and would have biological implications as well. It is therefore worth reassessing the potential for liquid water formation on present day Mars, particularly in light of recent Mars Global Surveyor observations. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Raytheon ITSS, Moffett Field, CA 94035 USA. SETI Inst, Mt View, CA 94043 USA. RP Haberle, RM (reprint author), NASA, Ames Res Ctr, Div Space Sci, M-S 245-3, Moffett Field, CA 94035 USA. NR 23 TC 147 Z9 148 U1 6 U2 27 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23317 EP 23326 DI 10.1029/2000JE001360 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900010 ER PT J AU Tyler, GL Balmino, G Hinson, DP Sjogren, WL Smith, DE Simpson, RA Asmar, SW Priest, P Twicken, JD AF Tyler, GL Balmino, G Hinson, DP Sjogren, WL Smith, DE Simpson, RA Asmar, SW Priest, P Twicken, JD TI Radio science observations with Mars Global Surveyor: Orbit insertion through one Mars year in mapping orbit SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SPECTROMETER TES OBSERVATIONS; GRAVITY-FIELD; GRAVITATIONAL-RADIATION; ABELIAN INVERSION; DOPPLER TRACKING; OCCULTATION DATA; SPACECRAFT; INERTIA; AEROBRAKING; TOPOGRAPHY AB Mars Global Surveyor (MGS) radio science comprises studies of the atmosphere and gravity of the planet. Perturbations of the 3.6-cm lambda radio path by the atmosphere during periods of atmospheric occultation provide the vertical temperature-pressure structure T[p(r)] to accuracies at the surface of DeltaT approximate to 0.4 K and Deltap approximate to 2 Pa, and similar to 10 K and similar to0.6 Pa at altitudes of 40-50 km; the error in radius is Deltar approximate to 1 m at all levels. Accurate knowledge of the radius permits fixing of the T-p structure to the geopotential and use of the gradient wind equation to calculate components of the wind. Systematic sampling of the atmosphere in combination with the accuracy of the MCS radio system supports studies of the large-scale dynamics of the atmosphere, including seasonal variations of the atmospheric fields and embedded waves such as Kelvin and Rossby waves. Terminator region ionospheric electron density profiles are obtained successfully much of the time but on occasion are undetectable with the MCS system. Two-way radio tracking of MGS with uncertainties in the line-of-sight velocity of several to tens of mum s(-1) and less supports solution for spherical harmonic models of the gravity field of order and degree in the range of 75x75, although the degree and order of meaningful terms is limited by the similar to 400 km spacecraft altitude to similar to 62x62, corresponding to a resolution of a few degrees of arc on the surface. This resolution of gravity is sufficient to support geophysical studies of the planet's interior structure and history. Additional radio science investigations include the search for gravitational radiation and observation of very low grazing angle forward scattering by the surface of Mars. C1 Stanford Univ, Dept Elect Engn, Stanford, CA 94305 USA. Ctr Natl Etud Spatiales, Grp Res Geodesie Spatiales, F-31401 Toulouse 4, France. Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Microsoft Corp, Seattle, WA USA. RP Tyler, GL (reprint author), Stanford Univ, Space Telecommun & Radio Sci Lab, 350 Serra Mall, Stanford, CA 94305 USA. NR 48 TC 59 Z9 61 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23327 EP 23348 DI 10.1029/2000JE001348 PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900011 ER PT J AU Tracadas, PW Zuber, MT Smith, DE Lemoine, FG AF Tracadas, PW Zuber, MT Smith, DE Lemoine, FG TI Density structure of the upper thermosphere of Mars from measurements of air drag on the Mars Global Surveyor spacecraft SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID THERMAL EMISSION SPECTROMETER; TES OBSERVATIONS; ATMOSPHERE; ORBIT; TEMPERATURES; AEROBRAKING AB We present measurements of the density of the Martian atmosphere between 170- and 180-km altitude above the high northern latitudes over a 6-month period in 1998, when the solar cycle was beginning to rise out of its activity minimum. These measurements were made from the observed orbital decay of the Mars Global Surveyor (MGS) spacecraft during its Science Phasing Orbits (SPO) (April to September 1998) using X band Doppler tracking observations. The densities that we retrieve are comparable to model values given by Culp and Stewart [1984], Stewart [1987], Mars-GRAM 3.7 [Justus et al., 1996], and recent Mars Thermospheric Global Circulation Model (MTGCM) simulations [Bougher et al., 2000]. However, the SPO period can be divided into two time periods (separated at L-S=355 degrees similar to0 degrees) that are characterized by significantly different orbit-to-orbit variability that is not predicted by these earlier models. The first time period corresponds to the time during which the MGS orbit perifocus moved toward the north pole while the local solar time was 1000-1100; during this period, orbit-to-orbit variability is 50-70%, and our average measured density at 175 km is 0.018 +/-0.007 kg km(-3) (between 67 degrees and 72 degreesN and L-S=315 degrees to 320 degrees). The second time period corresponds to the time during which the orbit perifocus moved south from the north pole and the local time was 1700-1730; during this period, orbit-to-orbit variability is 40-20%, and our average measured density at 175 km is 0.024 +/- 0.004 kg km(-3) (between 62 degrees and 69 degreesN and L-S=17 degrees to 28 degrees). For both time periods the observed latitudinal gradient of density on a constant altitude surface exhibited a factor of 3-4 decrease between 60 degrees and 90 degreesN. This gradient is comparable to that expected by the polar vortex (high-latitude wind) effect modeled by the MTGCM for solar medium conditions at southern summer solstice [Bougher et al., 2000]. A southern hemisphere dust storm that the MGS Thermal Emission Spectrometer (TES) observed at L-S = 309 degrees is distinguishable in our data set as a 100% rise in density at 180 km above the 70 degrees northern latitudes 7 days later (L-S = 313 degrees). C1 MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Tracadas, PW (reprint author), MIT, Dept Earth Atmospher & Planetary Sci, 77 Massachusetts Ave,Rm 54-521, Cambridge, MA 02139 USA. EM tracadas@mit.edu RI Lemoine, Frank/D-1215-2013 NR 31 TC 12 Z9 12 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9097 EI 2169-9100 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23349 EP 23357 DI 10.1029/2000JE001418 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900012 ER PT J AU Lemoine, FG Smith, DE Rowlands, DD Zuber, MT Neumann, GA Chinn, DS Pavlis, DE AF Lemoine, FG Smith, DE Rowlands, DD Zuber, MT Neumann, GA Chinn, DS Pavlis, DE TI An improved solution of the gravity field of Mars (GMM-2B) from Mars Global Surveyor SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MODEL; ORBIT; SATELLITES; TOPOGRAPHY; TRACKING; VIKING; TIME AB A spherical harmonic solution of the Mars gravity field to degree and order 80, Goddard Mars Model 2B (GMM-2B), has been developed using X band tracking data of Mars Global Surveyor (MGS) from October 1997 to February 2000 and altimeter crossovers formed from the Mars Orbiter Laser Altimeter (MOLA) data between March and December 1999. During the mapping mission, MGS was located in a near-polar (92.9 degrees inclination) and near-circular orbit at a mean altitude of 400 km. The tracking data from this orbit provide a detailed, global, and high resolution view of the gravity field of Mars. Mars gravity solutions are stable to 60 x 60 even without application of a Kaula power law constraint. The Valles Marineris is resolved distinctly with lows reaching -450 mGals. Olympus Mons and its aureole are both separately resolved, and the volcano has a peak anomaly of 2950 mGals. The global correlation of the GMM-2B gravity coefficients with MOLA-derived topography is 0.78 through degree 60, and the correlation remains above 0.6 through degree 62. The global gravity anomaly error predicted from the GMM-2B error covariance through 60 x 60 is 11 mGal. The global geoid error from GMM-2B through 60 x 60 is 1.8 m. MGS orbit quality using GMM-2B, as measured by overlapping orbital arcs, is 1 m in the radial direction and 10 m in total position. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. Raytheon ITSS Corp, Lanham, MD 20706 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Lemoine, FG (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Code 920, Greenbelt, MD 20771 USA. RI Rowlands, David/D-2751-2012; Lemoine, Frank/D-1215-2013; Neumann, Gregory/I-5591-2013 OI Neumann, Gregory/0000-0003-0644-9944 NR 50 TC 143 Z9 150 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23359 EP 23376 DI 10.1029/2000JE001426 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900013 ER PT J AU Yuan, DN Sjogren, WL Konopliv, AS Kucinskas, AB AF Yuan, DN Sjogren, WL Konopliv, AS Kucinskas, AB TI Gravity field of Mars: A 75th degree and order model SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GLOBAL SURVEYOR; TOPOGRAPHY; EVOLUTION; PHOBOS; VIKING AB Radiometric tracking data collected by NASA's Deep Space Network (DSN) for Mariner 9, Viking 1 and 2 orbiters, and Mars Global Surveyor (MGS) have been analyzed to determine the gravity field of Mars. The gravity solution (MGS75D) is a complete spherical harmonics model to degree and order 75. Also parts of the solution are the gravitational constants of Mars, Phobos, and Deimos. The significant improvement in the MGS75D Mars gravity model is mainly a consequence of globally distributed data set collected from the MGS mapping orbits, the use of optimal weighting and constrained least squares solution techniques, and improved force and measurement models in the orbit determination process. The gravity anomaly map reveals significantly more detail and larger amplitudes than any previous Mars gravity map over the major impact and volcanic areas on Mars. Olympus Mons remains the largest known gravity anomaly in our solar system and Isidis Planitia, the highest-amplitude mascon. There are mascons in the Hellas, Argyre, and Utopia basins. Valles Marineris has distinctive negative anomalies, and all volcanic features are positive. Gravity anomalies over several craters have also been resolved. The overall correlation of the MGS75D gravity anomaly map with topography derived from the Mars Orbiter Laser Altimeter (MOLA) is very high, while the polar regions display relatively poor correlation. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yuan, DN (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 65 TC 78 Z9 85 U1 2 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23377 EP 23401 DI 10.1029/2000JE001302 PG 25 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900014 ER PT J AU Acuna, MH Connerney, JEP Wasilewski, P Lin, RP Mitchell, D Anderson, KA Carlson, CW McFadden, J Reme, HR Mazelle, C Vignes, D Bauer, SJ Cloutier, P Ness, NF AF Acuna, MH Connerney, JEP Wasilewski, P Lin, RP Mitchell, D Anderson, KA Carlson, CW McFadden, J Reme, HR Mazelle, C Vignes, D Bauer, SJ Cloutier, P Ness, NF TI Magnetic field of Mars: Summary of results from the aerobraking and mapping orbits SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MARTIAN MAGNETOSPHERE; THERMAL EVOLUTION; SOLAR-WIND; HALLEY; BOUNDARY AB The Mars Global Surveyor (MGS) Magnetic Field Investigation was designed to provide fast vector measurements of the ambient magnetic field in the near-Mars environment and over a wide dynamic range. The fundamental objectives of this investigation were to (1) establish the nature of the magnetic field of Mars; (2) develop appropriate models for its representation; and (3) map the Martian crustal remanent field (if one existed) to a resolution consistent with the spacecraft orbit altitude and ground track separation. Important and complementary objectives were the study of the interaction of Mars with the solar wind and of its ionosphere. The instrumentation is a synergistic combination of a twin-triaxial, fluxgate magnetometer system and an electron reflectometer. The twin-magnetometer system allows the real-time detection of spacecraft-generated fields, while the electron reflectometer adds remote magnetic field sensing capabilities as well as information about the local electron population. After Mars orbit injection in September 1997 and through the aerobraking (AB) and science-phasing orbits (SPO) that followed, observations were acquired from more than 1000 elliptical orbits with periapses ranging from 85 to 170 km above Mars' surface. Following injection into the final similar to 400 km altitude circular-mapping orbit, data have been acquired from more than 6000 orbits in the fixed 02100-1400 local time plane. Major results obtained so far by the Magnetometer/Electron Reflectometer (MAG/ER) investigation in the course of the mission include (1) the determination that Mars does not currently possess a magnetic field of internal origin (dynamo), (2) the discovery of linear, strongly magnetized regions in its crust, closely associated with the ancient, cratered terrain of the highlands in the southern hemisphere, and (3) multiple magnetic "cusps" that connect the crustal magnetic sources to the Martian tail and shocked solar wind plasma. The solar wind interaction with Mars is therefore similar in many ways tic) that at Venus and at an active comet, primarily an ionospheric/atmospheric interaction. A comet-like "magnetic pileup" region and boundary develop that stand off the solar wind, and mass loading by pickup ions of planetary origin plays an important role in defining interaction regions and overall geometry. This paper focuses primarily on the results obtained by the magnetometer (MAG) portion of the investigation during the MGS aerobraking, science-phasing, and mapping orbits. A companion paper on this issue summarizes the results obtained from the Electron Reflectometer (ER) sensor. C1 NASA, Goddard Space Flight Ctr, Planetary Magnetospheres Branch, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Graz Univ, Inst Meteorol & Geophys, Graz, Austria. Rice Univ, Dept Space Sci, Houston, TX 77001 USA. Ctr Etud Spatiale Rayonnements, Toulouse, France. Univ Delaware, Bartol Res Inst, Newark, DE 19711 USA. RP Acuna, MH (reprint author), NASA, Goddard Space Flight Ctr, Planetary Magnetospheres Branch, Code 695, Greenbelt, MD 20771 USA. RI connerney, john/I-5127-2013; OI Bauer, Siegfried/0000-0003-4213-2047 NR 36 TC 196 Z9 202 U1 1 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23403 EP 23417 DI 10.1029/2000JE001404 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900015 ER PT J AU Mitchell, DL Lin, RP Mazelle, C Reme, H Cloutier, PA Connerney, JEP Acuna, MH Ness, NF AF Mitchell, DL Lin, RP Mazelle, C Reme, H Cloutier, PA Connerney, JEP Acuna, MH Ness, NF TI Probing Mars' crustal magnetic field and ionosphere with the MGS Electron Reflectometer SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MAG/ER EXPERIMENT; GLOBAL SURVEYOR; SOLAR-WIND; VENUS; IONIZATION; BOUNDARY AB The Electron Reflectometer (ER) on board Mars Global Surveyor measures the energy and angular distributions of solar wind electrons and ionospheric photoelectrons. These data can be used in conjunction with magnetometer data to probe Mars' crustal magnetic field and to study Mars' ionosphere and solar wind interaction. During aerobraking, ionospheric measurements were obtained in the northern hemisphere at high solar zenith angles (SZAs, typically similar to 78 degrees). The ionopause was crossed at altitudes ranging from 180 km to over 800 km, with a median of 380 km. The 400-km-altitude polar mapping orbit allows observations at SZAs from 25 degrees to 155 degrees in both the northern and southern hemispheres. The near-planet ionosphere and magnetotail structure of the night hemisphere is dominated by the presence of intense crustal magnetic fields, which can exceed 200 nT at the spacecraft altitude. Closed field lines anchored to highly elongated crustal sources form "magnetic cylinders," which exclude solar wind plasma traveling up the magnetotail. When the spacecraft passes through one of these structures, the ER count rate falls to the instrumental background, representing an electron flux drop of at least two orders of magnitude. A map of these flux dropouts in longitude and latitude closely resembles a map of the crustal magnetic sources. When the crustal magnetic cylinders rotate into sunlight, they fill with ionospheric plasma. Since many of these crustal fields are locally strong enough to stand off the solar wind to altitudes well above 400 km, the ionosphere can extend much higher than would otherwise be possible in the absence of crustal fields. Even weak crustal fields may locally bias the median ionopause altitude, which provides an indirect method of detecting crustal fields using ER observations. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Ctr Etud Spatiale Rayonnements, Toulouse, France. Rice Univ, Dept Phys & Astron, Houston, TX 77251 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. RP Mitchell, DL (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI connerney, john/I-5127-2013 NR 18 TC 179 Z9 178 U1 1 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23419 EP 23427 DI 10.1029/2000JE001435 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900016 ER PT J AU Smith, DE Zuber, MT Frey, HV Garvin, JB Head, JW Muhleman, DO Pettengill, GH Phillips, RJ Solomon, SC Zwally, HJ Banerdt, WB Duxbury, TC Golombek, MP Lemoine, FG Neumann, GA Rowlands, DD Aharonson, O Ford, PG Ivanov, AB Johnson, CL McGovern, PJ Abshire, JB Afzal, RS Sun, XL AF Smith, DE Zuber, MT Frey, HV Garvin, JB Head, JW Muhleman, DO Pettengill, GH Phillips, RJ Solomon, SC Zwally, HJ Banerdt, WB Duxbury, TC Golombek, MP Lemoine, FG Neumann, GA Rowlands, DD Aharonson, O Ford, PG Ivanov, AB Johnson, CL McGovern, PJ Abshire, JB Afzal, RS Sun, XL TI Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Review ID NORTH POLAR-REGION; RADIO OCCULTATION MEASUREMENTS; POLARIZATION RADAR OBSERVATIONS; SPECTROMETER TES OBSERVATIONS; THERMAL MAPPER OBSERVATIONS; PATHFINDER LANDING SITE; MOLA DATA; MARTIAN SURFACE; IMPACT BASINS; TOPOGRAPHIC SIGNATURE AB The Mars Orbiter Laser Altimeter (MOLA), an instrument on the Mars Global Surveyor spacecraft, has measured the topography, surface roughness, and 1.064-mum reflectivity of Mars and the heights of volatile and dust clouds. This paper discusses the function of the MOLA instrument and the acquisition, processing, and correction of observations to produce global data sets. The altimeter measurements have been converted to both gridded and spherical harmonic models for the topography and shape of Mars that have vertical and radial accuracies of similar to1 m with respect to the planet's center of mass. The current global topographic grid has a resolution of 1/64 degrees in latitude x 1/32 degrees in longitude (I x 2 km(2) at the equator). Reconstruction of the locations of incident laser pulses on the Martian surface appears to be at the 100-m spatial accuracy level and results in 2 orders of magnitude improvement in the global geodetic grid of Mars. Global maps of optical pulse width indicative of 100-m-scale surface roughness and 1.064-mum reflectivity with an accuracy of 5% have also been obtained. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Smith, DE (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Code 920, Greenbelt, MD 20771 USA. RI Rowlands, David/D-2751-2012; Sun, Xiaoli/B-5120-2013; Lemoine, Frank/D-1215-2013; Abshire, James/I-2800-2013; Neumann, Gregory/I-5591-2013; Ivanov, Anton/C-8944-2014; OI Neumann, Gregory/0000-0003-0644-9944; Ivanov, Anton/0000-0001-8376-8581; McGovern, Patrick/0000-0001-9647-3096 NR 211 TC 586 Z9 588 U1 18 U2 44 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23689 EP 23722 DI 10.1029/2000JE001364 PG 34 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900023 ER PT J AU Aharonson, O Zuber, MT Rothman, DH AF Aharonson, O Zuber, MT Rothman, DH TI Statistics of Mars' topography from the Mars Orbiter Laser Altimeter: Slopes, correlations, and physical Models SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID KILOMETER-SCALE SLOPES; MOLA DATA; SURFACE; EVOLUTION; REGION; VENUS; RADAR; MORPHOLOGY; ROUGHNESS; SEAFLOOR AB Data obtained recently by the Mars Orbiter Laser Altimeter (MOLA) were used to study the statistical properties of the topography and slopes on Mars. We find that the hemispheric dichotomy, manifested as an elevation difference, can be described by long baseline tilts but in places is expressed as steeper slopes. The bimodal hypsometry of elevations on Mars becomes unimodal when referenced to the center of figure, contrary to the Earth, for which the bimodality is retained. However, ruling out a model in which the elevation difference is expressed in a narrow equatorial topographic step cannot be done by the hypsometry alone. Mars' slope distribution is longer tailed than those of Earth and Venus, indicating a lower efficiency of planation processes relative to relief-building tectonics and volcanics. We define and compute global maps of statistical estimators, including the interquartile scale, RMS and median slope, and characteristic decorrelation length of the surface. A correspondence between these parameters and geologic units on Mars is inferred. Surface smoothness is distinctive in the vast northern hemisphere plains, where slopes are typically <0.5 degrees. Amazonis Planitia exhibits a variation in topography of <1 m over 35-km baselines. The region of hematite mineralization in Sinus Meridiani is also smooth, with median slopes lower than 0.4 degrees, but does not form a closed basin. The shallower long-wavelength portion of the lowlands' topographic power spectrum relative to the highlands' can be accounted for by a simple model of sedimentation such as might be expected at an ocean's floor. The addition of another process such as cratering is necessary to explain the spectral slope in short wavelengths. Among their application, these MOLA-derived roughness measurements can help characterize sites for landing missions. C1 MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. RP Aharonson, O (reprint author), MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NR 55 TC 61 Z9 62 U1 2 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23723 EP 23735 DI 10.1029/2000JE001403 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900024 ER PT J AU Neumann, GA Rowlands, DD Lemoine, FG Smith, DE Zuber, MT AF Neumann, GA Rowlands, DD Lemoine, FG Smith, DE Zuber, MT TI Crossover analysis of Mars Orbiter Laser Altimeter data SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GLOBAL SURVEYOR; NAVIGATION; TOPOGRAPHY; ERRORS AB In its first 15 months of continuous operation, the Mars Orbiter Laser Altimeter (MOLA) instrument aboard Mars Global Surveyor ranged to Mars over 330 million times, generating more than 5000 orbital profiles, with a ranging precision of 0.4 m over smooth terrain. The accuracy of the profiles depends on knowledge of the spacecraft position, orientation. and observation time, which are subject to errors. We model these errors via the analysis of over 24 million altimetric crossovers. A quasiperiodic. once per revolution adjustment of the ground tracks as a function of time in three locally orthogonal directions minimizes the altimetric residuals via least-squares. Using a sparse matrix technique, computational effort scales linearly with the number of crossovers and only marginally with the number of parameters. Orbital errors mainly result from poor modeling of spacecraft thrusting events in the absence of tracking. Seasonal effects. likely due to changing thermal environment, as well as residual miscalibrations, are evident in the pointing solutions. Incorporating multiple parameters per revolution significantly improves crossover residuals, and resolves pointing aberrations during orbital transitions from night to day. Altimetry from the adjusted tracks generates a topographic model whose accuracy is typically better than I m vertically with respect to the center of mass of Mars. The centroid position of each MOLA shot is typically accurate to similar to 100 in horizontally. Terrain models from accurately located lidar data can be gradient-shaded to illuminate geological structures with I in 1000 slopes that are invisible to cameras. Temporal changes in elevation (e.g., frost deposition/ablation) at decimeter levels may also be assessed using crossovers, but results must be interpreted with caution due to uncertainties in range walk correction. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. RP Neumann, GA (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Code 920, Greenbelt, MD 20771 USA. RI Rowlands, David/D-2751-2012; Lemoine, Frank/D-1215-2013; Neumann, Gregory/I-5591-2013 OI Neumann, Gregory/0000-0003-0644-9944 NR 40 TC 73 Z9 74 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23753 EP 23768 DI 10.1029/2000JE001381 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900026 ER PT J AU McGovern, PJ Solomon, SC Head, JW Smith, DE Zuber, MT Neumann, GA AF McGovern, PJ Solomon, SC Head, JW Smith, DE Zuber, MT Neumann, GA TI Extension and uplift at Alba Patera, Mars: Insights from MOLA observations and loading models SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID LARGE VOLCANOS; GALAPAGOS VOLCANOS; CRUSTAL STRUCTURE; GRABEN FORMATION; THARSIS REGION; TOPOGRAPHY; VENUS; ISLANDS; EVOLUTION; GRAVITY AB High-resolution Mars Orbiter Laser Altimeter (MOLA) profiles of the large shield volcano Alba Patera call for a critical reexamination of models for the growth and evolution of this volcanic edifice. An extensive system of graben cuts across Alba Patera, extending from Ceraunius Fossae to the south to Tantalus Fossae to the northeast. In the vicinity of the edifice, the otherwise generally north-south orientations of these graben are deflected to circumferential directions. MOLA topography reveals that the circumferential graben are located well up the flanks of Alba Patera. Both the type (extensional) and location (midflank) of faulting on Alba Patera are inconsistent with the state of stress predicted for purely surface-loaded flexure models. To constrain the conditions governing the evolution of Alba Patera, we employ finite element models for the volcano and lithospheric stress field under a combination of loading mechanisms. Buoyant sublithospheric loads (representing underplated magma, low-density mantle residuum, or dynamic support from mantle convection) and intralithospheric displacements (representing sills "trapped" by horizontal compressive stresses in the upper lithosphere) can generate the observed midflank slope breaks and circumferential extensional fault zones at radial distances comparable to that of the subsurface load's characteristic radial extent. Both mechanisms moderate stresses in the upper lithosphere in favor of continued magma ascent. However, bottom loading requires a disk-like load geometry and an elastic lithosphere thickness T-e sufficiently small to allow the load's shape to be apparent in the surface deformation (T-e less than or equal to 32 km). Such low T-e is inconsistent with Mars Global Surveyor (MGS) gravity and topography data. In contrast, intralithospheric sill complexes can produce the observed topography and faulting at T-e values consistent with those inferred from gravity and topography (50 less than or equal to T-e less than or equal to 100 km). For these conditions, principal stress orientations on the lower flanks are also consistent with the orientations of lower-flank graben, provided that faulting was induced by dike intrusion or tensile failure rather than shear failure. C1 Lunar & Planetary Inst, Houston, TX 77058 USA. Carnegie Inst Sci, Dept Terr Magnetism, Washington, DC 20015 USA. Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. RP McGovern, PJ (reprint author), Lunar & Planetary Inst, 3600 Bay Area Blvd, Houston, TX 77058 USA. EM mcgovern@lpi.usra.edu; scs@dtm.ciw.edu; James_Head_III@brown.edu; zuber@mit.edu RI Neumann, Gregory/I-5591-2013; OI Neumann, Gregory/0000-0003-0644-9944; McGovern, Patrick/0000-0001-9647-3096 NR 56 TC 18 Z9 18 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9097 EI 2169-9100 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23769 EP 23809 DI 10.1029/2000JE001314 PG 41 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900027 ER PT J AU Golombek, MP Anderson, FS Zuber, MT AF Golombek, MP Anderson, FS Zuber, MT TI Martian wrinkle ridge topography: Evidence for subsurface faults from MOLA SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID THARSIS PLATEAU; LUNAE-PLANUM; MARS; KINEMATICS; GEOMETRY; ORIGIN; DEFORMATION; TECTONICS; EVOLUTION; GRAVITY AB Mars Orbiter Laser Altimeter (MOLA) topography shows distinct elevation offsets across wrinkle ridges that can be explained simply by subsurface thrust faults. MOLA has provided the first reliable topographic data of wrinkle ridges to test models for their origin; although previous work has shown that wrinkle ridges result from compressional folding and faulting of near-surface units, the role of thrust faulting and its depth penetration have been argued. Topographic profiles across wrinkle ridges in Solis Planum, Lunae Planum, Tempe Terra, Xanthe Terra, Arcadia, Terra Sirenum, Thaumasia Planum, Arabia Terra, Syrtis Major, and Hesperia Planum show characteristic features such as superposed hills, crenulations, and elevation offsets between the plains on either side of the ridge. The characteristic elevation offsets between plains surfaces on either side of the ridges shown by MOLA are easily explained by subsurface thrust faults that underlie the ridges and produce the offset. In Solis Dorsa, wrinkle ridges are 10-20 km wide (well resolved by the 300 in spaced MOLA elevations), have a total relief of 80-250 m, and have elevation offsets of 50-180 in (well above the uncertainty in the MOLA elevations). MOLA topography shows that the plains decrease in elevation toward the southeast and are deformed into folds or arches not visible in images that are parallel to and in between the ridges. The elevations of the plains on either side of the ridges in Solis and Lunae Plana are characteristically down to the southeast and east, respectively, suggesting that faults beneath the wrinkle ridges offset the plains. This offset indicates underlying thrust faults that dip to the northwest and west, respectively, and systematically lower the southeast side of the plains. The observation that the elevation offsets across the ridges are maintained to the next ridge implies that the thrust fault penetrates to depths of tens of kilometers and thus well into the mechanical lithosphere. Small foreland basement uplifts on Earth, in which slip on shallowly dipping thrust faults in the crystalline basement is accommodated by folding in the overlying sedimentary rocks, appear to be broadly analogous to these groups of wrinkle ridges and suggest that they are examples of thick-skinned compressional deformation on Mars. These observations are not consistent with models for the formation of wrinkle ridges that involve folding of near-surface layers only or subsurface thrust faults that flatten into decollements at shallow depths. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. RP Golombek, MP (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 183-501, Pasadena, CA 91109 USA. NR 52 TC 36 Z9 37 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23811 EP 23821 DI 10.1029/2000JE001308 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900028 ER PT J AU Christensen, PR Bandfield, JL Hamilton, VE Ruff, SW Kieffer, HH Titus, TN Malin, MC Morris, RV Lane, MD Clark, RL Jakosky, BM Mellon, MT Pearl, JC Conrath, BJ Smith, MD Clancy, RT Kuzmin, RO Roush, T Mehall, GL Gorelick, N Bender, K Murray, K Dason, S Greene, E Silverman, S Greenfield, M AF Christensen, PR Bandfield, JL Hamilton, VE Ruff, SW Kieffer, HH Titus, TN Malin, MC Morris, RV Lane, MD Clark, RL Jakosky, BM Mellon, MT Pearl, JC Conrath, BJ Smith, MD Clancy, RT Kuzmin, RO Roush, T Mehall, GL Gorelick, N Bender, K Murray, K Dason, S Greene, E Silverman, S Greenfield, M TI Mars Global Surveyor Thermal Emission Spectrometer experiment: Investigation description and surface science results SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Review ID MARTIAN SURFACE; PARTICLE-SIZE; INFRARED SPECTROSCOPY; OPTICAL-CONSTANTS; SPECTRAL CONTRAST; SINUS-MERIDIANI; WESTERN-ARABIA; IGNEOUS ROCKS; GRAIN-SIZE; ATMOSPHERE AB The Thermal Emission Spectrometer (TES) investigation on Mars Global Surveyor (MGS) is aimed at determining (1) the composition of surface minerals, rocks, and ices; (2) the temperature and dynamics of the atmosphere; (3) the properties of the atmospheric aerosols and clouds; (4) the nature of the polar regions; and (5) the thermophysical properties of the surface materials. These objectives are met using an infrared (5.8- to 50-mum) interferometric spectrometer, along with broadband thermal (5.1- to 150-mum) and visible/near-IR (0.3- to 2.9-mum) radiometers. The MGS TES instrument weighs 14.47 kg, consumes 10.6 W when operating, and is 23.6 X 35.5 X 4.0.0 cm in size. The TES data are calibrated to a 1-sigma precision of 2.5(-6) X 10(-8) W cm(-2) sr(-1)/cm(-1), 1.6 X 10(-6) W cm(-2) sr(-1), and similar to0.5 K in the spectrometer, visible/near-IR bolometer, and IR bolometer, respectively. These instrument subsections are calibrated to an absolute accuracy of similar to4 X 10(-8) W cm(-2) sr(-1)/cm(-1) (0.5 K at 280 K), 1-2%, and similar to1-2 K., respectively. Global mapping of surface mineralogy at a spatial resolution of 3 km has shown the following: (1) The mineralogic composition of dark regions varies from basaltic, primarily plagioclase feldspar and clinopyroxene, in the ancient, southern highlands to andesitic, dominated by plagioclase feldspar and volcanic glass, in the younger northern plains. (2) Aqueous mineralization has produced gray, crystalline hematite in limited regions under ambient or hydrothermal conditions; these deposits are interpreted to be in-place sedimentary rock formations and indicate that liquid water was stable near the surface for a long period of time. (3) There is no evidence for large-scale (tens of kilometers) occurrences of moderate-grained (> 50-mum) carbonates exposed at the surface at a detection limit of similar to 10%. (4) Unweathered volcanic minerals dominate the spectral properties of dark regions, and weathering products, such as clays, have not been observed anywhere above a detection limit of similar to 10%; this lack of evidence for chemical weathering indicates a geologic history dominated by a cold, dry climate in which mechanical, rather than chemical, weathering was the significant form of erosion and sediment production. (5) There is no conclusive evidence for sulfate minerals at a detection limit of similar to 15%. The polar region has been studied with the following major conclusions: (1) Condensed CO2 has three distinct end-members, from fine-grained crystals to slab ice. (2) The growth and retreat of the polar caps observed by MGS is virtually the same as observed by Viking 12 Martian years ago. (3) Unique regions have been identified that appear to differ primarily in the grain size of CO2; one south polar region appears to remain as black slab CO2 ice throughout its sublimation. (4) Regional atmospheric dust is common in localized and regional dust storms around the margin and interior of the southern cap. Analysis of the thermophysical properties of the surface shows that (1) the spatial pattern of albedo has changed since Viking observations, (2) a unique cluster of surface materials with intermediate inertia and albedo occurs that is distinct from the previously identified low-inertia/bright and high-inertia/dark surfaces, and (3); localized patches of high-inertia material have been found in topographic lows and may have been formed by a unique set of aeolian, fluvial, or erosional processes or may be exposed bedrock. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. US Geol Survey, Flagstaff, AZ 86001 USA. Malin Space Sci Syst, San Diego, CA 92191 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. US Geol Survey, Denver, CO 80225 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Space Sci Inst, Boulder, CO USA. Raytheon Santa Barbara Remote Sensing, Goleta, CA USA. Vernadsky Inst, Moscow, Russia. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Christensen, PR (reprint author), Arizona State Univ, Dept Geol, Campus Box 871404, Tempe, AZ 85287 USA. EM phil.christensen@asu.edu RI Smith, Michael/C-8875-2012; Mellon, Michael/C-3456-2016 NR 121 TC 507 Z9 510 U1 16 U2 70 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9097 EI 2169-9100 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23823 EP 23871 DI 10.1029/2000JE001370 PG 49 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900029 ER PT J AU Christensen, PR Morris, RV Lane, MD Bandfield, JL Malin, MC AF Christensen, PR Morris, RV Lane, MD Bandfield, JL Malin, MC TI Global mapping of Martian hematite mineral deposits: Remnants of water-driven processes on early Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INFRARED-EMISSION SPECTROSCOPY; SURFACE; SPECTRA; SPECTROMETER; EVOLUTION; FEATURES; OCEANS; ORIGIN; TES AB Near-global (60 degreesS to 60 degreesN) thermal infrared mapping by the Thermal Emission Spectrometer (TES) on Mars Global Surveyor has revealed unique deposits of crystalline gray hematite (alpha -Fe2O3) exposed at the Martian surface in Sinus Meridiani, Aram Chaos, and in numerous scattered locations throughout Valles Marineris. The Sinus Meridiani material is an in-place, rock stratigraphic sedimentary unit characterized by smooth, friable layers composed primarily of basaltic sediments with similar to 10-15% crystalline gray hematite. This unit has outliers to the north that appear to have formed by stripping and removal. The hematite within Aram Chaos occurs in a sedimentary layer within a closed basin that was likely formed during the basin infilling and predates the formation of nearby chaos and outflow terrains. This unit appears to be exposed by erosion and may be more extensive beneath the surface. The Valles Marineris occurrences are closely associated with the interior layered deposits and may be in place within the layers or eroded sediments. Overall, crystalline gray hematite is extremely uncommon at the surface, yet in all observed locations it is closely associated with layered, sedimentary units. Here we argue that these hematite deposits have formed by a process involving chemical precipitation from aqueous fluids, under either ambient or hydrothermal conditions. Thus the TES mineralogic data provide evidence that liquid water has been stable at or near the surface, probably for millions of years by analogy with terrestrial iron formations, in specific locations on early Mars. C1 Arizona State Univ, Dept Geol Sci, Tempe, AZ 85287 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Malin Space Sci Syst, San Diego, CA 92191 USA. RP Christensen, PR (reprint author), Arizona State Univ, Dept Geol Sci, Box 871404, Tempe, AZ 85287 USA. NR 53 TC 187 Z9 192 U1 4 U2 18 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23873 EP 23885 DI 10.1029/2000JE001415 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900030 ER PT J AU Ruff, SW Christensen, PR Clark, RN Kieffer, HH Malin, MC Bandfield, JL Jakosky, BM Lane, MD Mellon, MT Presley, MA AF Ruff, SW Christensen, PR Clark, RN Kieffer, HH Malin, MC Bandfield, JL Jakosky, BM Lane, MD Mellon, MT Presley, MA TI Mars' "White Rock" feature lacks evidence of an aqueous origin: Results from Mars Global Surveyor SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID THERMAL EMISSION SPECTROMETER; PLAYA EVAPORITE MINERALS; MARTIAN SURFACE; DEATH-VALLEY; CALIFORNIA; TES AB The "White Rock" feature on Mars has long been viewed as a type example for a Martian playa largely because of its apparent high albedo along with its location in a topographic basin (a crater). Data from the Mars Global Surveyor Thermal Emission Spectrometer (TES) demonstrate that White Rock is not anomalously bright relative to other Martian bright regions, reducing the significance of its albedo and weakening the analogy to terrestrial playas. Its thermal inertia value indicates that it is not mantled by a layer of loose dust, nor is it bedrock. The thermal infrared spectrum of White Rock shows no obvious features of carbonates or sulfates and is, in fact, spectrally flat. Images from the Mars Orbiter Camera show that the White Rock massifs are consolidated enough to retain slopes and allow the passage of saltating grains over their surfaces. Material appears to be shed from the massifs and is concentrated at the crests of nearby bedforms. One explanation for these observations is that White Rock is an eroded accumulation of compacted or weakly cemented aeolian sediment. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. US Geol Survey, Denver, CO 80225 USA. US Geol Survey, Flagstaff, AZ 86002 USA. Malin Space Sci Syst, San Diego, CA 92191 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Ruff, SW (reprint author), Arizona State Univ, Dept Geol, POB 871404, Tempe, AZ 85287 USA. RI Mellon, Michael/C-3456-2016 NR 31 TC 35 Z9 35 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23921 EP 23927 DI 10.1029/2000JE001329 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900033 ER PT J AU Smith, MD Pearl, JC Conrath, BJ Christensen, PR AF Smith, MD Pearl, JC Conrath, BJ Christensen, PR TI Thermal Emission Spectrometer results: Mars atmospheric thermal structure and aerosol distribution SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID HUBBLE-SPACE-TELESCOPE; INFRARED-SPECTROSCOPY; TES OBSERVATIONS; DUST OPACITY; PATHFINDER; VIKING; MARINER-9; TEMPERATURES; AEROBRAKING; APHELION AB Infrared spectra returned by the Thermal Emission Spectrometer (TES) are well suited for retrieval of the thermal structure and the distribution of aerosols in the Martian atmosphere. Combined nadir- and limb-viewing spectra allow global monitoring of the atmosphere up to 0.01 mbar (65 km). We, report here on the atmospheric thermal structure and the distribution of aerosols as observed thus far during the mapping phase of the Mars Global Surveyor mission. Zonal and temporal mean cross sections are used to examine the seasonal evolution of atmospheric temperatures and zonal winds during a period extending from northern hemisphere midsummer through vernal equinox (L-S = 104 degrees -360 degrees). Temperature maps at selected pressure levels provide a characterization of planetary-scale waves. Retrieved atmospheric infrared dust opacity maps show the formation and evolution of regional dust storms during southern hemisphere summer. Response of the atmospheric thermal structure to the changing dust loading is observed. Maps of water-ice clouds as viewed in the thermal infrared are presented along with seasonal trends of infrared water-ice opacity. Uses of these observations for diagnostic studies of the dynamics of the atmosphere are discussed. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. RP Smith, MD (reprint author), NASA, Goddard Space Flight Ctr, Code 693, Greenbelt, MD 20771 USA. RI Smith, Michael/C-8875-2012 NR 29 TC 162 Z9 162 U1 1 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD OCT 25 PY 2001 VL 106 IS E10 BP 23929 EP 23945 DI 10.1029/2000JE001321 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 488FQ UT WOS:000171925900034 ER PT J AU Wal, RLV Ticich, TM AF Wal, RLV Ticich, TM TI Flame and furnace synthesis of single-walled and multi-walled carbon nanotubes and nanofibers SO JOURNAL OF PHYSICAL CHEMISTRY B LA English DT Article ID DIFFUSION FLAME; IRON CATALYST; GROWTH; PARTICLES; SOOT; ADSORPTION; PYROLYSIS; FIBERS; SULFUR; VAPORIZATION AB Results are presented for flame synthesis of metal-catalyzed carbon nanotubes. A thermal evaporation technique is used to create the catalyst nanoparticles of Fe or Ni through gas condensation followed by entrainment into the flame. Results are compared with those using a high-temperature tube furnace to provide the reactive environment. Each system yields consistent results, with CO/H2 mixtures generally yielding single-walled nanotubes (SWNTs) with Fe while C2H2/H2 mixtures usually produce multiwalled nanotubes (MWNTs) with Ni. A ternary gas mixture of CO/C2/H2 produces a better yield of nanofibers than either a COM2 or C2H2/H2 mixture at 700 degreesC with Ni catalyst. Our results reflect a combination or possibly a synergy between thermal- plus adsorbate-induced restructuring and adsorbate-particle steric factors affecting particle structure and reactivity. C1 NASA Glenn, NCMR, Cleveland, OH 44135 USA. Centenary Coll Louisiana, Dept Chem, Shreveport, LA 71134 USA. RP NASA Glenn, NCMR, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. EM randy@rvander.grc.nasa.gov NR 55 TC 5 Z9 6 U1 0 U2 13 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1520-6106 J9 J PHYS CHEM B JI J. Phys. Chem. B PD OCT 25 PY 2001 VL 105 IS 42 BP 10249 EP 10256 DI 10.1021/jp012838u PG 8 WC Chemistry, Physical SC Chemistry GA 486EH UT WOS:000171805100015 ER PT J AU Chaban, GM Lundell, J Gerber, RB AF Chaban, GM Lundell, J Gerber, RB TI Lifetime and decomposition pathways of a chemically bound helium compound SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID SELF-CONSISTENT-FIELD; NOBLE-GAS CHEMISTRY; AB-INITIO; ELECTRON CORRELATION; WAVE-FUNCTIONS; BASIS-SETS; RARE-GAS; XENON; SPECTROSCOPY; KRYPTON AB HHeF, a first predicted chemically-bound helium compound, is a metastable species that disintegrates by tunneling through energy barriers into He+HF and H+He+F. The reaction paths for these decomposition processes are calculated with single-configurational Moller-Plesset (MP2) and multiconfigurational quasidegenerate MCQDPT2/MCSCF(10,6) electronic structure methods. The lifetime of HHeF, estimated using a one-dimensional model along the minimum energy path and the semiclassical WKB approximation, is more than 120 ps, that of DHeF is 14 ns. The relatively long lifetimes are encouraging for the preparation prospects of this helium compound. (C) 2001 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Helsinki, Chem Phys Lab, FIN-00014 Helsinki, Finland. Hebrew Univ Jerusalem, Dept Phys Chem, IL-91904 Jerusalem, Israel. Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. RP Chaban, GM (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. EM bgerber@uci.edu NR 21 TC 41 Z9 41 U1 1 U2 4 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 22 PY 2001 VL 115 IS 16 BP 7341 EP 7343 DI 10.1063/1.1412467 PG 3 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 484YT UT WOS:000171719200001 ER PT J AU de Jager, C Lobel, A Nieuwenhuijzen, H Stothers, R AF de Jager, C Lobel, A Nieuwenhuijzen, H Stothers, R TI Instability regions in the upper HR diagram SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE stars : atmospheres; stars : evolution; Hertzsprung -Russell (HR) diagram; stars : interiors; supergiants ID WOLF-RAYET STARS; MASS-LOSS; HYPERGIANT IRC+10420; YELLOW HYPERGIANTS; SUPERGIANTS; EVOLUTION; STABILITY; SODIUM AB The following instability regions for blueward evolving-supergiants are outlined and compared. (1) Areas in the Hertzsprung-Russell (HR) diagram where stars are dynamically unstable. (2) Areas where the effective acceleration in the upper part of the photospheres is negative, hence directed outward. (3) Areas where the sonic points of the stellar winds (where nu (wind) = nu (sound)) are situated inside the photospheres, at a level deeper than tau (Ross) = 0.01. We compare the results with the positions of actual stars in the HR diagram and we find evidence that the recent strong contraction of the yellow hypergiant HR 8752 was initiated in a period during which [g(eff)] < 0, whereupon the star became dynamically unstable. The instability and extreme shells around IRC + 10420 are suggested to be related to three factors: [g(eff)] < 0; the sonic point is situated inside the photosphere; and the star is dynamically unstable. C1 SRON, Space Res Lab, NL-3584 CA Utrecht, Netherlands. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP de Jager, C (reprint author), SRON, Space Res Lab, Sorbonnelaan 2, NL-3584 CA Utrecht, Netherlands. NR 28 TC 20 Z9 20 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD OCT 21 PY 2001 VL 327 IS 2 BP 452 EP 458 DI 10.1046/j.1365-8711.2001.04791.x PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 484LZ UT WOS:000171693000011 ER PT J AU Hair, JW Caldwell, LM Krueger, DA She, CY AF Hair, JW Caldwell, LM Krueger, DA She, CY TI High-spectral-resolution lidar with iodine-vapor filters: measurement of atmospheric-state and aerosol profiles SO APPLIED OPTICS LA English DT Article ID ROTATIONAL RAMAN LIDAR; ATOMIC BLOCKING FILTERS; RAYLEIGH-SCATTERING; ABSORPTION FILTER; MESOPAUSE REGION; DOPPLER LIDAR; RADIAL WIND; TEMPERATURE; DENSITY; RADAR AB A high-spectral-resolution lidar can measure vertical profiles of atmospheric temperature, pressure, the aerosol backscatter ratio, and the aerosol extinction coefficient simultaneously. We describe a system with these characteristics. The transmitter is a narrow-band (FWHM of the order of 74 MHz), injection-seeded, pulsed, double YAG laser at 532 nm. Iodine-vapor filters in the detection system spectrally separate the molecular and aerosol scattering and greatly reduce the latter (-41 dB). Operating at a selected frequency to take advantage of two neighboring lines in vapor filters, one can obtain a sensitivity of the measured signal-to-air temperature ratio equal to 0.42%/K. Using a relatively modest size transmitter and receiver system (laser power times telescope aperture equals 0.19 Wm(2)), our measured temperature profiles (0.5-15 km) over 11 nights are in agreement with balloon soundings to within 2.0 K over an altitude range of 2-5 km. There is good agreement in the lapse rates, tropopause altitudes, and inversions. In principle, to invert the signal requires a known density at one altitude, but in practice it is convenient to also use a known temperature at that altitude. This is a scalable system for high spatial resolution of vertical temperature profiles in the troposphere and lower stratosphere, even in the presence of aerosols. (C) 2001 Optical Society of America. C1 Colorado State Univ, Dept Phys, Ft Collins, CO 80523 USA. RP Hair, JW (reprint author), NASA, Langley Res Ctr, Mail Stop 401A, Hampton, VA 23681 USA. EM Krueger@lamar.colostate.edu NR 33 TC 73 Z9 78 U1 2 U2 19 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD OCT 20 PY 2001 VL 40 IS 30 BP 5280 EP 5294 DI 10.1364/AO.40.005280 PG 15 WC Optics SC Optics GA 483BL UT WOS:000171613800002 PM 18364809 ER PT J AU Strickland, DK Colbert, EJM Heckman, TM Weaver, KA Dahlem, M Stevens, IR AF Strickland, DK Colbert, EJM Heckman, TM Weaver, KA Dahlem, M Stevens, IR TI Another intermediate-mass black hole in a starburst galaxy? The luminous X-ray source in NGC 3628 reappears SO ASTROPHYSICAL JOURNAL LA English DT Article DE black hole physics; galaxies : individual (NGC 3628); galaxies : starburst; X-rays : galaxies ID RADIO SUPERNOVAE; SPIRAL GALAXIES; NGC-3628; EMISSION; M82; NUCLEUS; REGIONS AB In a 52 ks long Chandra X-Ray Observatory ACIS-S observation of the nearby starburst galaxy NGC 3628, obtained to study the starburst-driven outflow from this galaxy, we have detected a very luminous (L(X)approximate to1.1 x 10(40) ergs s(-1) in the 0.3-8.0 keV energy band) point source located at least 20 " from the nucleus of the galaxy. No radio, optical, or near-IR counterpart to this source has been found. This is most probably the reappearance of the strongly variable X-ray luminous source discovered by Dahlem, Heckman, & Fabbiano, which faded by a factor of greater than or similar to 27 between 1991 December and 1994 March (at which point it had faded below the detection limit in a ROSAT HRI observation). This source is clearly a member of an enigmatic class of X-ray sources that are considerably more luminous than conventional X-ray binaries but less luminous than active galactic nuclei and which are not found at the dynamical center of the host galaxy. The Chandra spectrum is best fitted by an absorbed power-law model with a photon index of Gamma =1.8 +/-0.2, similar to that seen in Galactic black hole binary candidates in their hard state. Bremsstrahlung models or multicolor disk models (the favored spectral model for objects in this class on the basis of ASCA observations) can provide statistically acceptable fits only if the data at energies E>5 keV are ignored. This is one of the first X-ray spectra of such an object that is unambiguously that of the source alone, free from the spectral contamination by X-ray emission from the rest of the galaxy that affects previous spectral studies of these objects using ASCA. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. European So Observ, Santiago 19, Chile. Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. RP Strickland, DK (reprint author), Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. NR 47 TC 54 Z9 54 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 707 EP 714 DI 10.1086/323055 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000018 ER PT J AU Shelton, RL Kruk, JW Murphy, EM Andersson, BG Blair, WP Dixon, WV Edelstein, J Fullerton, AW Gry, C Howk, JC Jenkins, EB Linsky, JL Moos, HW Oegerle, WR Oey, MS Roth, KC Sahnow, DJ Sankrit, R Savage, BD Sembach, KR Shull, JM Siegmund, OHW Vidal-Madjar, A Welsh, BY York, DG AF Shelton, RL Kruk, JW Murphy, EM Andersson, BG Blair, WP Dixon, WV Edelstein, J Fullerton, AW Gry, C Howk, JC Jenkins, EB Linsky, JL Moos, HW Oegerle, WR Oey, MS Roth, KC Sahnow, DJ Sankrit, R Savage, BD Sembach, KR Shull, JM Siegmund, OHW Vidal-Madjar, A Welsh, BY York, DG TI Observations of O VI emission from the diffuse interstellar medium SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxy : general; galaxy : halo; ISM : general; ISM : structure; ultraviolet : ISM ID MOLECULAR-HYDROGEN; LOCAL BUBBLE; H-I; BAND SYSTEM; GAS; ABSORPTION; HEMISPHERE; CLOUD; HALO; HOT AB We report the first Far-Ultraviolet Spectroscopic Explorer measurements of diffuse O VI (lambda lambda 1032, 1038) emission from the general diffuse interstellar medium outside of supernova remnants or superbubbles. We observed a 30 " x30 " region of the sky centered at l=315 degrees .0 and b = -41 degrees .3. From the observed intensities (2930 +/- 290 [random] +/- 410 [systematic] and 1790 +/- 260 [random] +/- 250 [systematic] photons cm(-2) s(-1) sr(-1) in lambda lambda 1032 and 1038, respectively), derived equations, and assumptions about the source location, we calculate the intrinsic intensity, electron density, thermal pressure, and emitting depth. The intensities are too large for the emission to originate solely in the Local Bubble. Thus, we conclude that the Galactic thick disk and lower halo also contribute. High-velocity clouds are ruled out because there are none near the pointing direction. The calculated emitting depth is small, indicating that the O VI-bearing gas fills a small volume. The observations can also be used to estimate the cooling rate of the hot interstellar medium and to constrain models. The data also yield the first intensity measurement of the C II 3s S-2(1/2)-2p P-2(3/2) emission line at 1037 Angstrom and place upper limits on the intensities of ultraviolet line emission from C I, CIII, Si II, S III, S IV, S VI, and Fe III. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. European Space Agcy, Div Astrophys, ISO Data Ctr, Madrid 28080, Spain. Astron Spatiale Lab, F-13376 Marseille 12, France. Princeton Univ Observ, Princeton, NJ 08544 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Colorado, Dept Astrophys Planetary & Sci, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Lowell Observ, Flagstaff, AZ 86001 USA. Gemini Observ, Hilo, HI 96720 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA. Inst Astrophys Paris, Paris, France. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Shelton, RL (reprint author), Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RI Oegerle, William/C-9070-2012; Kruk, Jeffrey/G-4047-2012; Howk, Jay/D-2577-2013; Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 59 TC 43 Z9 43 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 730 EP 741 DI 10.1086/322478 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000021 ER PT J AU Hwang, U Petre, R Holt, SS Szymkowiak, AE AF Hwang, U Petre, R Holt, SS Szymkowiak, AE TI The thermal X-ray-emitting shell of Large Magellanic Cloud supernova remnant 0540-69.3 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (LMC 0540.69.3); supernovae remnants; X-rays : ISM ID CRAB-NEBULA; PULSAR; ABUNDANCES; EMISSION; DISCOVERY; ELEMENTS; SN-1006 AB We use data from the Advanced CCD Imaging Spectrometer (ACIS) on the Chandra X-Ray Observatory to image the shell surrounding the pulsar B0540-69.3 and measure its spectral properties. Weak emission-line features, notably of Fe, Mg, and Si, indicate that the shell is composed primarily of ambient material heated by the blast wave. The shell emission in the east is faint and circular in appearance, with a temperature and ionization age of approximately 5 keV and 10(10) cm(-3) s, respectively. The emission in the west is brighter and has a more complex, distorted morphology and is fitted with significantly lower average temperatures and higher ionization ages. An image with photon energies above 2 keV shows two hard arcs of emission located diametrically opposite each other at the outer boundary of the remnant shell; the spectra from these regions could include a substantial nonthermal component. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. FW Olin Coll Engn, Needham, MA 02492 USA. RP Hwang, U (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 27 TC 19 Z9 19 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 742 EP 748 DI 10.1086/322962 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000022 ER PT J AU Raymond, JC Li, J Blair, WP Cornett, RH AF Raymond, JC Li, J Blair, WP Cornett, RH TI Shock wave emission at Miller's position 1 in the Cygnus Loop SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (Cygnus Loop); shock waves; supernova remnants; ultraviolet : ISM ID HOPKINS-ULTRAVIOLET-TELESCOPE; SUPERNOVA REMNANT N49; INTERSTELLAR-MEDIUM; RADIATIVE SHOCKS; X-RAY; BLAST WAVE; EVOLUTION; CLOUDS; ACCELERATION; STABILITY AB We present the far-UV spectrum (900-1800 Angstrom) of the bright filament known as Miller's (1974) position 1 in the Cygnus Loop obtained with the Hopkins Ultraviolet Telescope during the Astro-2 space shuttle mission. Longer wavelength IUE and ground-based spectra of adjoining regions were scaled to produce a combined spectrum ranging from 900 to 7500 Angstrom. We compare this spectrum with models of radiative shock waves to infer shock velocities and elemental abundances. A power-law distribution of shock velocities within the spectrograph apertures can reproduce the observed spectrum. We consider the question of whether a simpler shock structure, thermally unstable cooling, or a mixing layer could produce a similar spectrum. We also discuss the elemental abundances with particular attention to C and Si, whose lines are only available in the UV. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Raytheon STX Corp, Greenbelt, MD 20771 USA. RP Raymond, JC (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. NR 49 TC 6 Z9 6 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 763 EP 771 DI 10.1086/322953 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000024 ER PT J AU Ikeda, M Ohishi, M Nummelin, A Dickens, JE Bergman, P Hjalmarson, A Irvine, WM AF Ikeda, M Ohishi, M Nummelin, A Dickens, JE Bergman, P Hjalmarson, A Irvine, WM TI Survey observations of c-C2H4O and CH3CHO toward massive star-forming regions SO ASTROPHYSICAL JOURNAL LA English DT Article DE astrochemistry; ISM : abundances; ISM : clouds; ISM : evolution; ISM : molecules ID SUBMILLIMETER-WAVE SPECTRUM; DENSE INTERSTELLAR CLOUDS; H-II REGIONS; CONTAINING ORGANIC-MOLECULES; ETHYLENE-OXIDE C-C2H4O; ASTROPHYSICAL INTEREST; MICROWAVE-SPECTRA; TEMPERATURE PROBE; METHYL ACETYLENE; MILLIMETER-WAVE AB In order to clarify the formation mechanisms of ethylene oxide (cyclic-C2H4O, hereafter c-C2H4O) its structural isomer acetaldehyde (CH3CHO), we carried out survey observations of these two molecules toward 20 massive star-forming regions and two dark clouds. CH3CHO and c-C2H4O were detected in 10 massive star-forming regions, and CH3CHO was also detected in five others. The column densities and the rotational temperatures were derived using the rotation diagram method. The column densities of these molecules were derived to be (0.1-3.3) x 10(14) and (0.2-5.0) x 10(14) cm(-2) for c-C2H2O and CH3CHO, respectively. The fractional abundances with respect to H-2 are X(c-C2H4O) = 4 x 10(-11) to 6 x 10(-10) and X(CH3CHO) = 7 x 10(-12) to 3 x 10(-9). We also detected several transitions of methanol (CH3OH), ethanol (C2H5OH), dimethyl ether [(CH3)(2)O], methyl formate (HCOOCH3), formic acid (HCOOH), vinyl cyanide (C2H3CN), and ethyl cyanide (C2H5CN). Comparing the abundances of the detected molecules with physical conditions of each source, we found that the abundances of most of the molecules except for c-C2H4O and CH3CHO increase along with the dust temperature of each source. On the other hand, the abundances of c-C2H4O and CH3CHO show little correlation with the dust temperature. The rotation temperatures of c-C2H4O, CH3CHO, and HCOOH are low (10-40 K) in all sources in spite of the fact that the gas kinetic temperature greatly varies from cloud to cloud. This may indicate that the line emission from each molecular species is excited in regions with different physical conditions. We performed pseudo-time-dependent chemical reaction simulations based on pure gasphase reactions and found that the calculated abundances of observed molecules decreased when the gas kinetic temperature was raised. We investigated the relationship between the column density of C2H5OH and that of the C2H4O group (c-C2H4O + CH3CHO) because C2H5OH is believed to be a precursor of c-C2H4O and CH3CHO in the gas-phase chemistry scheme. If this hypothesis is correct, it is expected that the column density of C2H5OH is related to that of the C2H4O group. We found that the column density of the C2H4O group is high in sources where the column density of C2H5OH is high. This result is consistent with the above-mentioned hypothesis. We also investigated the relationships between the column densities of several organic species [CH3OH, C2H5OH, (CH3)(2)O, HCOOCH3, C2H3CN, and C2H5CN] and the luminosity-to-mass ratio, L-IR/M, in OMC-1, W51A, and Sgr B2(N). We found that the column densities of these molecules are high in sources where L-IR/M is high. Since L-IR/M is believed to be a measure of the star formation rate per unit mass, it indicates that the column densities of these molecules become higher in sources where high star formation activity leads to a higher dust temperature. This strongly suggests that the formation of these molecules involves processes on the dust grains and subsequent sublimation to the gas phase, where they can be observed. C1 Natl Astron Observ, Tokyo 1818588, Japan. Chalmers Lindholmen Univ, Dept Elect & Comp Engn, SE-40272 Gothenburg, Sweden. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Chalmers, Onsala Space Observ, S-43992 Onsala, Sweden. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. RP Natl Astron Observ, 2-21-1 Osawa, Tokyo 1818588, Japan. EM miho.ikeda@nao.ac.jp; masatoshi.ohnishi@nao.ac.jp; albert.nummelin@chl.chalmers.se; jdickens@mail1.jpl.nasa.gov; bergman@oso.chalmers.se; hjalmar@oso.chalmers.se; irvine@fcrao1.astro.umass.edu NR 54 TC 100 Z9 100 U1 0 U2 12 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 792 EP 805 DI 10.1086/322957 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000027 ER PT J AU Lyu, CH Smith, AM Bruhweiler, FC AF Lyu, CH Smith, AM Bruhweiler, FC TI A search for interstellar CH2 toward HD 154368 and zeta Ophiuchi SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : molecules ID TRANSLUCENT MOLECULAR CLOUDS; HIGH-RESOLUTION SPECTROGRAPH; ABUNDANCES; CN; HD-154368; CARBON; MODELS; C2; CO AB We have searched for molecular CH2 in the interstellar gas in the line of sight to HD 154368 and zeta Oph to constrain further the gas-phase chemistry of carbon-bearing molecules in the cool, translucent clouds toward these stars. We report tentative detection of CH2 in the interstellar spectra of both stars. In zeta Oph, slight depressions in the stellar continuum are seen near 1410.1 and 1415.8 Angstrom corresponding to band structure in CH2, while in HD 154368 a single, narrow feature is found at 1410 Angstrom that may be due to CH2. Assuming that these features are produced by CH2, the column densities of CH2 toward HD 154368 and zeta Oph are (5.9 +/- 3.1) x 10(13) cm(-2) (W-lambda 1410.1 = 5.2 m Angstrom) and (3.3 +/- 1.9) x 10(13) cm(-2) (W-lambda 1415.8 = 29 mA), respectively. Although the oscillator strengths for the relevant electronic transitions are somewhat problematic, our deduced column densities are within a factor of 2-5 of those predicted by the model chemistry. These observations may represent the first detection of CH2 interstellar absorption in any astronomical object. Additional theoretical estimates and laboratory measurements of relevant oscillator strengths are needed to provide more accurate estimates of CH2 column densities and stronger constraints on the carbon chemistry in these interstellar molecular clouds. C1 NASA, Goddard Space Flight Ctr, Caelum Res Corp, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. RP Lyu, CH (reprint author), NASA, Goddard Space Flight Ctr, Caelum Res Corp, Code 975, Greenbelt, MD 20771 USA. NR 26 TC 4 Z9 4 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 865 EP 870 DI 10.1086/322426 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000032 ER PT J AU Nayakshin, S Dove, JB AF Nayakshin, S Dove, JB TI Accretion disks with coronae in Cygnus X-1: The role of a transition layer SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; galaxies : Seyfert; magnetic fields; radiative transfer ID ACTIVE GALACTIC NUCLEI; X-RAY REFLECTION; LINE; INSTABILITY; RADIATION; EVOLUTION; BINARIES; GALAXIES; MODELS; DISCS AB Several recent papers have shown that an accretion disk corona model, where a slab corona sandwiches the cold accretion disk, is problematic for hard-state spectra of galactic black hole candidates (GBHCs) because the model spectra are never hard enough to match the observations. However, it has recently been pointed out that because of a thermal ionization instability, a hot "skin" forms on the top of the illuminated disk. Through numerical simulations in the slab corona geometry, we show that the completely ionized skin leads to a reduction in the reflected thermal blackbody component that amounts to a decrease in the Compton cooling rate of the corona and thus allows the X-ray spectra to be harder. While this brings the model closer to observations, in order for the predicted spectrum to be as hard as the observed spectra of Cyg X-1, the Thomson optical depth of the transition layer must be greater than 10, which is inconsistent with the ionization physics and observations. Therefore, the model with a planar corona covering the whole accretion disk is still strongly ruled out by the observations of GBHCs. Finally, we discuss accretion disks with magnetic flares (i.e., "patchy" corona) and show that the ionized skin resolves many of the arguments made in the literature against this model, although more quantitative future work is needed to test the model thoroughly. C1 Univ Arizona, Dept Phys, Tucson, AZ 85721 USA. Metropolitan State Coll, Dept Phys, Denver, CO 80217 USA. RP Nayakshin, S (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 52 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 885 EP 891 DI 10.1086/323045 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000034 ER PT J AU Wijnands, R Mendez, M Markwardt, C van der Klis, M Chakrabarty, D Morgan, E AF Wijnands, R Mendez, M Markwardt, C van der Klis, M Chakrabarty, D Morgan, E TI The erratic luminosity behavior of SAX J1808.4-3658 during its 2000 outburst SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; stars : individual (SAX J1808.4-3658); X-rays : stars ID X-RAY; MILLISECOND PULSAR; QUIESCENCE AB We report on the highly variable and erratic long-term X-ray luminosity behavior of the only known accretion-driven millisecond X-ray pulsar SAX J1808.4-3658 during its 2000 outburst, as observed with the Rossi X-ray Timing Explorer (RXTE) satellite. The maximum observed luminosity is similar to2.5-10(35) ergs s(-1) (3-25 keV; for a distance of 2.5 kpc), which is approximately a factor of 10 lower than that observed during the 1996 and 1998 outbursts. Due to solar constraints, the source could not be observed for several months with RXTE before 2000 January 21. Therefore, the exact moment of the outburst onset is unknown, and the peak luminosity could have been significantly higher. On some occasions SAX J1808.4-3658 was observed with luminosities of similar to 10(35) ergs s(-1), but on other occasions it could not be detected with RXTE, resulting in typical upper limits of a few times 10(33) ergs s(-1) (3-25 keV). The nondetections of the source during its 2000 outburst obtained with the BeppoSAX satellite demonstrate that its luminosity was at times less than 10(32) ergs s(-1) (0.5-10 keV). However, only a few days after these BeppoSAX observations, we detected the source again with RXTE at high luminosities, giving a factor of greater than 1000 of luminosity swings in this systems on timescales of days. The last detection of SAX J1808.4-3658 with RXTE was on 2000 May 13, almost 4 months after the first detection during this outburst. Due to the lack of sensitivity and observations during the 1996 and 1998 outbursts, it cannot be excluded that after those outbursts the source remained active for months and that the source behavior during the 2000 outburst is not unique. Long duration activity at low luminosities has been observed in other transients (both neutron stars and black holes), although not with such extreme variability, which might point to a different origin for this behavior for the millisecond X-ray pulsar. C1 MIT, Ctr Space Res, Cambridge, MA 02139 USA. SRON, Space Res Lab, NL-3584 CA Utrecht, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. RP MIT, Ctr Space Res, 77 Massachusetts Ave, Cambridge, MA 02139 USA. EM rudy@space.mit.edu RI Mendez, Mariano/C-8011-2012 OI Mendez, Mariano/0000-0003-2187-2708 NR 25 TC 34 Z9 34 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 892 EP 896 DI 10.1086/323073 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000035 ER PT J AU Stothers, RB Chin, CW AF Stothers, RB Chin, CW TI Yellow hypergiants as dynamically unstable post-red supergiant stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : evolution; stars : mass loss; stars : oscillations; stars : variables : other ID MASSIVE STARS; RHO-CASSIOPEIAE; SEMIREGULAR VARIABLES; STELLAR MODELS; PHOTOMETRY; EVOLUTION; HR-8752; GRIDS AB According to recent theoretical studies, the majority of single stars more massive than 30 M. successfully evolve into red supergiants but then lose most of their hydrogen envelopes and metamorphose into hot blue remnants. While they are cool, they become dynamically unstable as a result of high radiation pressure and partial ionization of the gases in their outer layers. It is shown here that these unstable red supergiant models repeatedly shrink and reexpand on a thermal timescale when perturbed by heavy bursts of mass loss. Consequently, they fill up the domain of yellow hypergiants on the Hertzsprung-Russell diagram and display very fast rates of evolution there, as observed. C1 NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. RP Stothers, RB (reprint author), NASA, Goddard Space Flight Ctr, Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 24 TC 13 Z9 13 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 934 EP 936 DI 10.1086/322438 PN 1 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000041 ER PT J AU Worden, JR Woods, TN Bowman, KW AF Worden, JR Woods, TN Bowman, KW TI Far-ultraviolet intensities and center-to-limb variations of active regions and quiet sun using UARS SOLSTICE irradiance measurements and ground-based spectroheliograms SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : activity; Sun : faculae, plages; Sun : UV radiation ID MAGNETIC-FLUX TRANSPORT; SOLAR CHROMOSPHERE; COMPARISON EXPERIMENT-1; LYMAN-ALPHA; VARIABILITY; NETWORK; EVOLUTION; SPECTRUM; FIELDS; INTRANETWORK AB The average intensity and center-to-limb variation of active regions, enhanced network (large-scale active region fragments), and quiet Sun are estimated by minimizing the variance between time series of the Solar-Stellar Irradiance Comparison Experiment (SOLSTICE) far-ultraviolet (FUV) irradiance measurements and a model of the solar irradiance that depends on the distribution of solar surface features. The model is constrained by grouping the broad range of solar features into four components that contribute the most to solar irradiance variability over the solar activity cycle. The areas of these components arc identified on approximately 800 ground-based Ca II K spectroheliograms with an algorithm that uses criteria of size, filling factor, intensity, and contiguity. These 800 maps are the "known" parameters to the solar irradiance model. The unknown parameters to this model are the average intensities and center-to-limb variation of these four components. Because of systematic uncertainties associated with the SOLSTICE measurements and the Ca II K maps we are limited to reporting the computed intensities and center-to-limb variation of active regions, enhanced network, and quiet Sun for wavelengths between 120.0 and 170.0 nm. We find good spectral agreement between active region center-to-limb variations and image-based measurements of quiet-Sun center-to-limb variations. Intensities for plage, enhanced network, and quiet Sun are reported with a typical uncertainty of about 8%. This uncertainty is primarily associated with the SOLSTICE FUV calibration. C1 Raytheon ITSS, Pasadena, CA 91101 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. RP Raytheon ITSS, 299 N Euclid Ave, Pasadena, CA 91101 USA. NR 54 TC 14 Z9 14 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 1020 EP 1034 DI 10.1086/323058 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000049 ER PT J AU Sterling, AC Moore, RL AF Sterling, AC Moore, RL TI EIT crinkles as evidence for the breakout model of solar eruptions SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : coronal mass ejections (CMEs); Sun : flares; Sun : particle emission; Sun : UV radiation; Sun : X-rays, gamma rays ID CORONAL MASS EJECTIONS; BRAGG CRYSTAL SPECTROMETER; X-RAY TELESCOPE; TRANSITION REGION; A MISSION; FE-XXV; CA-XIX; FLARES; PLASMA; EVOLUTION AB We present observations of two homologous flares in NOAA Active Region 8210 occurring on 1998 May 1 and 2, using EUV data from the EUV Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory, high-resolution and high-time cadence images from the soft X-ray telescope on Yohkoh, images or fluxes from the hard X-ray telescope on Yohkoh and the BATSE experiment on board the Compton Gamma Ray Observatory, and Ca XIX soft X-ray spectra from the Bragg crystal spectrometer (BCS) on Yohkoh. Magnetograms indicate that the flares occurred in a complex magnetic topology, consisting of an emerging flux region (EFR) sandwiched between a sunspot to the west and a coronal hole to the east. In an earlier study we found that in EIT images, both flaring episodes showed the formation of a crinkle-like pattern of emission ("EIT crinkles") occurring in the coronal hole vicinity, well away from a central "core field" area near the EFR-sunspot boundary. With our expanded data set, here we find that most of the energetic activity occurs in the core region in both events, with some portions of the core brightening shortly after the onset of the EIT crinkles, and other regions of the core brightening several minutes later, coincident with a burst of hard X-rays; there are no obvious core brightenings prior to the onset of the EIT crinkles. These timings are consistent with the "breakout model" of solar eruptions, whereby the emerging flux is initially constrained by a system of overlying magnetic field lines, and is able to erupt only after an opening develops in the overlying fields as a consequence of magnetic reconnection at a magnetic null point. In our case, the EIT crinkles would be a signature of this pre-impulsive phase magnetic reconnection, and brightening of the core only occurs after the core fields begin to escape through the newly created opening in the overlying fields. Morphology in soft X-ray images and properties in hard X-rays differ between the two events, with complexities that preclude a simple determination of the dynamics in the core at the times of eruption. From the BCS spectra, we find that the core region expends energy at a rate of similar to 10(26) ergs s(-1) during the time of the growth of the EIT crinkles; this rate is an upper limit to energy expended in the reconnections opening the overlying fields. Energy losses occur at an order of magnitude higher rate near the time of the peak of the events. There is little evidence of asymmetry in the spectra, consistent with the majority of the mass flows occurring normal to the line of sight. Both events have similar electron temperature dependencies on time. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. RP Sterling, AC (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, SD 50, Huntsville, AL 35812 USA. NR 36 TC 38 Z9 38 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP 1045 EP 1057 DI 10.1086/322241 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TM UT WOS:000171652000051 ER PT J AU Hwang, U Szymkowiak, AE Petre, R Holt, SS AF Hwang, U Szymkowiak, AE Petre, R Holt, SS TI Bulk X-ray Doppler velocities in the supernova remnant Cassiopeia A SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (Cassiopeia A); supernova remnants; X-rays : general ID CORE-COLLAPSE SUPERNOVA; EJECTA; SPECTROSCOPY; EXPLOSIONS; DRIVEN; WAVES; JET AB We map the average line-of-sight velocities of the X-ray-emitting mass in the supernova remnant Cassiopeia A using measurements of the centroid of the Si-He alpha blend with the Advanced CCD Imaging Spectrometer on the Chandra X-Ray Observatory. This 4" scale map confirms the broad trends noted in previous studies, namely, that the line-of-sight velocity scale is roughly 2000-3000 km s(-1), with relatively more blueshifted material in the southeastern region of the remnant than in the northwest; new details are that the northwestern region consists of two arcs, with the southernmost one representing the most redshifted X-ray-emitting material in Cas A. These results are consistent with contemporaneous results from XMM-Newton. The X-ray patterns resemble the complex velocity patterns measured at optical wavelengths for much denser ejecta, and they support the growing body of evidence that the explosion and subsequent evolution of Cas A were highly asymmetrical. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Yale Univ, Dept Phys, New Haven, CT 06520 USA. FW Olin Coll Engn, Needham, MA 02492 USA. RP Hwang, U (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 28 TC 17 Z9 17 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP L175 EP L179 DI 10.1086/324177 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TT UT WOS:000171652500017 ER PT J AU Kubota, A Makishima, K Ebisawa, K AF Kubota, A Makishima, K Ebisawa, K TI Observational evidence for strong disk comptonization in GRO J1655-40 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; stars : individual (GRO J1655-40); X-rays : stars ID BLACK-HOLE CANDIDATES; OPTICAL LIGHT-CURVE; X-RAY SOURCES; ACCRETION DISKS; LMC X-3 AB An analysis was made of the multiple Rossi X-Ray Timing Explorer/Proportional Counter Array data on the candidate black hole binary system with superluminal jet, GRO J1655-40, acquired during its 1996-1997 outburst. The X-ray spectra can be adequately described by the sum of an optically thick disk spectrum and a power law. When the estimated 1-100 keV power-law luminosity exceeds 1 x 10(37) ergs s(-1) (assuming a distance of 3.2 kpc), the inner disk radius and the maximum color temperature derived from a simple accretion disk model (a multicolor disk model) vary significantly with time. These results reconfirm the previous report by Sobczak and coworkers. In this strong power-law state (once called the "very high state"), the disk luminosity decreases with temperature, in contradiction to the prediction of the standard Shakura-Sunyaev model. In the same state, the power-law component becomes stronger and steeper (softer), as the disk component decreases in intensity, suggesting that some of the strong power-law emission is simply the missing optically thick disk emission. One possible explanation for this behavior is inverse Compton scattering around the disk. By refitting the same data incorporating a disk Comptonization model, the inner radius and temperature of the underlying disk are found to become more constant. These results provide one of the first observational confirmations of the scenario of disk Comptonization in the strong power-law state. This strong power-law state seems to appear when the color temperature of the disk exceeds a certain threshold, similar to 1.2-1.3 keV. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Tokyo, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan. Inst Phys & Chem Res, Cosm Radiat Lab, Itabashi Ku, Tokyo 173, Japan. RP Kubota, A (reprint author), Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Kanagawa 2298510, Japan. NR 23 TC 86 Z9 86 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP L147 EP L150 DI 10.1086/324377 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TT UT WOS:000171652500010 ER PT J AU Wijnands, R Miller, JM Markwardt, C Lewin, WHG van der Klis, M AF Wijnands, R Miller, JM Markwardt, C Lewin, WHG van der Klis, M TI A Chandra observation of the long-duration X-ray transient KS 1731-260 in quiescence: Too cold a neutron star? SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; stars : individual (KS 1731-260); X-rays : stars ID BURSTER KS-1731-260; ASCA; PULSARS; ROSAT AB After more than a decade of actively accreting at about a tenth of the Eddington critical mass accretion rate, the neutron star X-ray transient KS 1731-260 returned to quiescence in early 2001. We present a Chandra/ Advanced CCD Imaging Spectrometer observation taken several months after this transition. We detected the source at an unabsorbed flux of similar to2 x 10(-13) ergs cm(-2) s(-1) (0.5-10 keV). For a distance of 7 kpc, this results in a 0.5-10 keV luminosity of similar to1 x 10(33) ergs s(-1) and a bolometric luminosity approximately twice that. This quiescent luminosity is very similar to that of the other quiescent neutron star systems. However, if this luminosity is due to the cooling of the neutron star, this low luminosity may indicate that the source spends at least several hundreds of years in quiescence in between outbursts for the neutron star to cool. If true, then it might be the first such X-ray transient to be identified, and a class of hundreds of similar systems may be present in the Galaxy. Alternatively, enhanced neutrino cooling could occur in the core of the neutron star that would cool the star more rapidly. However, in that case, the neutron star in KS 1731-260 would be more massive than those in the prototypical neutron star transients (e.g., Aquila X-1 or 4U 1608-52). C1 MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. RP Wijnands, R (reprint author), MIT, Ctr Space Res, 77 Massachusetts Ave, Cambridge, MA 02139 USA. NR 37 TC 84 Z9 84 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2001 VL 560 IS 2 BP L159 EP L162 DI 10.1086/324378 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 483TT UT WOS:000171652500013 ER PT J AU Paulson, AJ AF Paulson, AJ TI Biogeochemical removal of Zn and Cd in the Coeur d'Alene River (Idaho, USA), downstream of a mining district SO SCIENCE OF THE TOTAL ENVIRONMENT LA English DT Article DE acid drainage; zinc; cadmium; biogeochemistry; Coeur d'Alene River; metal-organic complexation ID SURFACE WATERS; HEAVY-METALS; CU; SEDIMENTS; PHYTOPLANKTON; GROUNDWATER; STREAMS; PB AB The conservative biogeochemical behavior of dissolved Zn and Cd in a 17-km, free-flowing reach of the Coeur d'Alene River downstream of a mining district is typical of watersheds in which suspended matter concentrations are low. For watersheds impacted by acid-rock drainage (ARD), low suspended matter concentrations are more likely to be found when acid rock drainage travels through soils because much of the Fe and Al that could form adsorbing surfaces is retained within the soils. In the absence of additional sources of solid substrates, metals can be transported great distances downstream once this Fe- and Al-poor ARD seeps into surface waters. In a 46-km backwater reach of the Coeur d'Alene River, it appears that biological activity increased pH and provided the organic matter solid substrate which removed approximately 50% of the Zn and Cd. Zn removal was partially reversible as pH decreased. These observations reinforce the concept that both inorganic and organic carbon chemistry must be measured if significant advances in our understanding of the attenuation of Zn and Cd from ARD sources are to be made. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NOAA, Natl Marine Fisheries Serv, NEFSC, James J Howard Lab, Highlands, NJ 07732 USA. RP Paulson, AJ (reprint author), NOAA, Natl Marine Fisheries Serv, NEFSC, James J Howard Lab, 74 Magruder Rd, Highlands, NJ 07732 USA. NR 27 TC 11 Z9 12 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0048-9697 J9 SCI TOTAL ENVIRON JI Sci. Total Environ. PD OCT 20 PY 2001 VL 278 IS 1-3 BP 31 EP 44 DI 10.1016/S0048-9697(00)00886-X PG 14 WC Environmental Sciences SC Environmental Sciences & Ecology GA 482EB UT WOS:000171560900004 PM 11669275 ER PT J AU Walther, JH Jaffe, R Halicioglu, T Koumoutsakos, P AF Walther, JH Jaffe, R Halicioglu, T Koumoutsakos, P TI Carbon nanotubes in water: Structural characteristics and energetics SO JOURNAL OF PHYSICAL CHEMISTRY B LA English DT Article ID MOLECULAR-DYNAMICS; SUPERCRITICAL WATER; VIBRATIONAL-MODES; HYDROGEN STORAGE; LIQUID WATER; GRAPHITE; WALL; SIMULATION; ADSORPTION; SOLVENTS AB We study the structural properties of water surrounding a carbon nanotube using molecular dynamics simulations. The interaction potentials involve a description of the carbon nanotube using Morse, harmonic bending, torsion, and Lennard-Jones potentials. The water is described by the flexible Simple Point Charge (SPC) model by Teleman et al.,(1) and the carbon-water interactions include a carbon-oxygen Lennard-Jones potential, and an electrostatic quadrupole moment acting between the carbon atoms and the charge sites of the water. Vibration of the breathing mode of the carbon nanotube in water is inferred from the oscillations in carbon-carbon van der Waals energy, and the inverse proportionality between the radius of the carbon nanotube and the breathing frequency is in good agreement with experimental values. The results indicate, that under the present conditions, the presence of the water has a negligible influence on the breathing frequency. The water at the carbon-water interface is found to have a HOH plane nearly tangential to the interface, and the water radial density profile exhibits the characteristic layering also found in the graphite-water system. The average number of hydrogen bonds decreases from a value of 3.73 in the bulk phase to a value of 2.89 at the carbon-water interface. The inclusion of the carbon quadrupole moment is found to have a negligible influence on the structural properties of the water. Energy changes that occur by the process of introducing a carbon nanotube in water are calculated. The creation of a cavity in the bulk water to accommodate the nanotube constitutes the largest energy contribution. Results include an analysis of surface structure and energy values for planar and for concave cylindrical surfaces of water. C1 NASA, Ames Res Ctr, Ctr Turbulence Res, Moffett Field, CA 94035 USA. ETH Zentrum, Inst Computat Sci, CH-8092 Zurich, Switzerland. Eloret Corp, Sunnyvale, CA USA. RP Koumoutsakos, P (reprint author), NASA, Ames Res Ctr, Ctr Turbulence Res, Moffett Field, CA 94035 USA. RI Koumoutsakos, Petros/A-2846-2008; Walther, Jens/D-9549-2015 OI Koumoutsakos, Petros/0000-0001-8337-2122; Walther, Jens/0000-0001-8100-9178 NR 52 TC 333 Z9 339 U1 2 U2 94 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5647 J9 J PHYS CHEM B JI J. Phys. Chem. B PD OCT 18 PY 2001 VL 105 IS 41 BP 9980 EP 9987 DI 10.1021/jp011344u PG 8 WC Chemistry, Physical SC Chemistry GA 483BY UT WOS:000171614900012 ER PT J AU Pravdo, SH Feigelson, ED Garmire, G Maeda, Y Tsuboi, Y Bally, J AF Pravdo, SH Feigelson, ED Garmire, G Maeda, Y Tsuboi, Y Bally, J TI Discovery of X-rays from the protostellar outflow object HH2 SO NATURE LA English DT Article ID HERBIG-HARO OBJECTS; EMISSION; SHOCK AB Herbig-Haro (HH) objects have been known(1,2) for 50 years to be luminous condensations of gas in star-forming regions, but their underlying physical nature is still being elucidated. Previously suggested models encompass newborn stars(3), stellar winds clashing with nebular material(4), dense pockets of interstellar gas excited by shocks from outflows(5), and interstellar 'bullets' (ref. 6). Recent progress has been made with the jet-induced shock model(7), in which material streams out of young stellar objects and collides with the surrounding interstellar medium. A clear prediction of this model is that the most energetic Herbig-Haro objects will emit X-rays, although they have not hitherto been detected(8). Here we report the discovery of X-ray emission from one of the brightest and closest Herbig-Haro objects, HH2, at a level consistent with the model predictions. We conclude that this Herbig-Haro object contains shock-heated material located at or near its leading edge with a temperature of about 10(6) K. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Penn State Univ, Dept Astron & Astrophys, DAvey Lab 525, University Pk, PA 16802 USA. Univ Colorado, Boulder, CO 80309 USA. RP Pravdo, SH (reprint author), CALTECH, Jet Prop Lab, Mail Stop 306-438,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 23 TC 93 Z9 93 U1 0 U2 1 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD OCT 18 PY 2001 VL 413 IS 6857 BP 708 EP 711 DI 10.1038/35099508 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 482ZK UT WOS:000171608000036 PM 11607024 ER PT J AU Zou, Y Vahdat, N Collins, M AF Zou, Y Vahdat, N Collins, M TI Fire protection with bromoalkene/nitrogen gaseous mixtures SO INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH LA English DT Article AB The fire suppression efficiencies of 1-bromo-1-propene/nitrogen and 2-bromo-3,3,3 trifluoro-1-propene/nitrogen gas mixtures were studied by a cup burner method. It was shown that addition of 1-bromo-1-propene and 2-bromo-3,3,3 trifluoro-1-propene to nitrogen can improve the suppression effectiveness of the inert gas by 34.5 and 64.3%, respectively. An arrangement for mixing organic compounds with inert gases before application to fire was proposed, and it was shown that droplets of bromoalkenes with diameters as large as 100 mum can be vaporized in less than 1 s. C1 Tuskegee Univ, Coll Engn Architecture & Phys Sci, Dept Chem Engn, Tuskegee, AL 36088 USA. NASA, Kennedy Space Ctr, FL 32899 USA. RP Vahdat, N (reprint author), Tuskegee Univ, Coll Engn Architecture & Phys Sci, Dept Chem Engn, Tuskegee, AL 36088 USA. NR 15 TC 7 Z9 7 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0888-5885 J9 IND ENG CHEM RES JI Ind. Eng. Chem. Res. PD OCT 17 PY 2001 VL 40 IS 21 BP 4649 EP 4653 DI 10.1021/ie010281z PG 5 WC Engineering, Chemical SC Engineering GA 481NR UT WOS:000171526300020 ER PT J AU Qin, WH Herman, JR Ahmad, Z AF Qin, WH Herman, JR Ahmad, Z TI A fast, accurate algorithm to account for non-Lambertian surface effects on TOA radiance SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RADIATIVE-TRANSFER; MULTIPLE-SCATTERING; ATMOSPHERE; REFLECTANCE; POLARIZATION; MEDIA AB Surface bidirectional reflectance distribution function (BRDF) influences both the radiance just above the surface and that emerging from the top of the atmosphere (TOA). In this study we propose a new, fast, and accurate algorithm CASBIR (correction for anisotropic surface bidirectional reflection) to account for such influences on TOA radiance. This new algorithm is based on four-stream theory that separates the radiation field into direct and diffuse components in both upwelling and downwelling directions. Such a separation is important because the direct component accounts for a substantial portion of incident radiation under a clear sky, and the BRDF effect is strongest in the reflection of the incident direct radiation. The model is validated by comparison with a full-scale, vector radiative transfer model for the atmosphere-surface system [Ahmad and Fraser, 1982] for wavelengths from UV to near-IR over three typical but very different surface types. The result demonstrates that CASBIR is accurate for all solar and viewing zenith and azimuth angles considered, with overall relative difference of less than 0.7%. Application of this algorithm includes both accounting for non-Lambertian surface scattering on the emergent radiation above TOA and developing a more effective approach for surface BRDF retrieval from satellite-measured radiance. Comparison with the result from the Lambertian model indicates that surface BRDF influence on TOA radiance is both angle and wavelength dependent. It increases as solar zenith angle decreases or wavelength increases and becomes strongest in the view directions where the surface reflection is most anisotropic (such as in the hot spot or Sun glint regions). C1 NASA, Goddard Space Flight Ctr, Atmospher Chem & Dynam Branch, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. Sci & Data Syst Inc, Silver Spring, MD 20906 USA. RP Qin, WH (reprint author), NASA, Goddard Space Flight Ctr, Atmospher Chem & Dynam Branch, Code 916, Greenbelt, MD 20771 USA. EM wqin@dmouse.gsfc.nasa.gov OI Herman, Jay/0000-0002-9146-1632 NR 26 TC 15 Z9 15 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 16 PY 2001 VL 106 IS D19 BP 22671 EP 22684 DI 10.1029/2001JD900215 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 481UJ UT WOS:000171538600008 ER PT J AU Weinstock, EM Hintsa, EJ Kirk-Davidoff, DB Anderson, JG Andrews, AE Herman, RL Webster, CR Loewenstein, M Podolske, JR Bui, TP AF Weinstock, EM Hintsa, EJ Kirk-Davidoff, DB Anderson, JG Andrews, AE Herman, RL Webster, CR Loewenstein, M Podolske, JR Bui, TP TI Constraints on the seasonal cycle of stratospheric water vapor using in situ measurements from the ER-2 and a CO photochemical clock SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LOWER TROPICAL STRATOSPHERE; SUBVISIBLE CIRRUS CLOUDS; DIODE-LASER SPECTROMETER; GAS EXPERIMENT-II; UPPER TROPOSPHERE; RESIDUAL CIRCULATION; CARBON-DIOXIDE; PIPE MODEL; NASA ER-2; UARS DATA AB We use in situ measurements of CO obtained in the tropics from 1995 to 1997 on the NASA ER-2 aircraft and a simple photochemical model to calculate the elapsed time between the entry of air into the stratosphere and the observation, which we define as the photochemical "age" of the air. Assuming this age represents the transit time of the air mass from a boundary at 390 K to its measured altitude, we calculate boundary condition values of CO2 derived from in situ measurements of this species from 400 to 480 K. We validate the approach by comparing these CO2 boundary values with an independent representation of the boundary condition from observations Of CO2 in air that had recently entered the stratosphere (as indicated by simultaneous measurements of N2O, CO, and potential temperature). For five of the six flights, differences between CO2 boundary condition values determined using the photochemical age of the air and those derived from independent measurements can be accounted for with isentropic mixing of midlatitude stratospheric air into the tropics. Having validated the photochemical ages of the sampled stratospheric air, we use the same analysis of in situ water data to provide water vapor boundary condition values that constrain the seasonal cycle of water vapor entering the stratosphere. On the basis of these constraints we evaluate the seasonal cycle of entry-level water vapor derived from tropical tropopause temperatures from the radiosonde network between 10 degreesS and 10 degreesN. We conclude that while average saturation mixing ratios provide a suitable boundary condition for water vapor entering the stratosphere, the uncertainties in saturation mixing ratios derived from radiosonde temperatures and the lack of coverage prevents distinguishing between ascent preferentially occurring over the western equatorial Pacific or throughout the tropics. With the assumption that vertical diffusion and midlatitude mixing have a negligible effect on the calculated age, ascent velocities can be inferred from the photochemical ages. These ascent velocities show a seasonal cycle that is inconsistent with our current understanding of the dynamics driving the stratospheric circulation and with independent estimates of tropical vertical ascent rates. C1 Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02138 USA. Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Weinstock, EM (reprint author), Harvard Univ, Dept Chem & Biol Chem, 12 Oxford St, Cambridge, MA 02138 USA. EM elliot@huarp.harvard.edu; davidoff@huarp.harvard.edu; anderson@huarp.harvard.edu RI Kirk-Davidoff, Daniel/F-2667-2010; Herman, Robert/H-9389-2012; Andrews, Arlyn/K-3427-2012 OI Herman, Robert/0000-0001-7063-6424; NR 66 TC 8 Z9 8 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 16 PY 2001 VL 106 IS D19 BP 22707 EP 22724 DI 10.1029/2000JD000047 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 481UJ UT WOS:000171538600011 ER PT J AU Feingold, G Remer, LA Ramaprasad, J Kaufman, YJ AF Feingold, G Remer, LA Ramaprasad, J Kaufman, YJ TI Analysis of smoke impact on clouds in Brazilian biomass burning regions: An extension of Twomey's approach SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DROPLET NUMBER CONCENTRATIONS; OPTICAL-PROPERTIES; SULFATE AEROSOLS; EFFECTIVE RADIUS; ALBEDO; MICROPHYSICS; CLIMATE; POLLUTION; PARTICLES; RADIATION AB Satellite remote sensing of smoke aerosol-cloud interaction during the recent Smoke, Clouds, and Radiation-Brazil (SCAR-B) experiment is analyzed to explore the factors that determine the magnitude of the cloud response to smoke aerosol. Analysis of 2 years worth of data revealed that the response is greatest in the north of Brazil where aerosol optical depth is smallest, and tends to decrease as one moves southward, and as aerosol optical depth increases. Saturation in this response occurs at an aerosol optical depth of 0.8 in 1987 and 0.4 in 1995. To explore the reasons for this, a framework is developed in which the satellite-measured response can be compared to simple analytical models of this response and to numerical models of smoke aerosol-cloud interaction. Three types of response are identified: (1) cloud droplet concentrations increase with increasing aerosol loading, followed by saturation in the response at high concentrations; (2) as in type 1, followed by increasing droplet concentrations with further increases in aerosol loading. This increase in droplet concentration is due to the suppression of supersaturation by abundant large particles, which prevents the activation of smaller particles. This enables renewed activation of larger particles when smoke loadings exceed some threshold; (3) as in type 1, followed by a decrease in droplet number concentrations with increasing aerosol loading as intense competition for vapor evaporates the smaller droplets. The latter implies an unexpected increase in drop size with increasing smoke loading. The conditions under which each of these responses are expected to occur are discussed. It is shown that although to first-order smoke optical depth is a good proxy for aerosol indirect forcing, under some conditions the size distribution and hygroscopicity can be important factors. We find no evidence that indirect forcing depends on precipitable water vapor. C1 NOAA, ETL, Boulder, CO 80305 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20777 USA. RP Feingold, G (reprint author), NOAA, ETL, 325 Broadway, Boulder, CO 80305 USA. EM graham.feinfold@noaa.gov RI Feingold, Graham/B-6152-2009 NR 38 TC 99 Z9 101 U1 5 U2 16 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 16 PY 2001 VL 106 IS D19 BP 22907 EP 22922 DI 10.1029/2001JD000732 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 481UJ UT WOS:000171538600024 ER PT J AU Pinker, RT Pandithurai, G Holben, BN Dubovik, O Aro, TO AF Pinker, RT Pandithurai, G Holben, BN Dubovik, O Aro, TO TI A dust outbreak episode in sub-Sahel West Africa SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AEROSOL OPTICAL-PROPERTIES; SKY RADIANCE MEASUREMENTS; SAHARAN DUST; SATELLITE RETRIEVAL; SIZE DISTRIBUTION; SMOKE PARTICLES; UNITED-STATES; AVHRR DATA; CLIMATE; MODEL AB Wind blown dust is a major contributor to the tropospheric aerosol mass loading and has a significant effect on the local radiative forcing. Information on aerosol optical properties and their temporal and spatial distribution is very limited. Attempts to derive such information from space, in particular, over land, are in a preliminary stage. Recently, information on aerosol optical properties is becoming available from ground networks within one day from the time the observations are made. In this study, use was made of such "real-time" aerosol observations, to characterize their optical properties, during a heavy dust event in the sub-Sahel in January 2000. Aerosol optical depths at all wavelengths showed a sharp increase when compared to the average for the season, reaching values up to 3.5 at 500 nm. The Angstrom exponent was reduced from 1.2 to 0.3, and a sharp increase in the single-scattering albedo was found. The aerosol optical properties differed significantly from climatologically available information on dust aerosols, and therefore their timely assimilation into transport models or weather prediction models could be of great relevance. Developments in the ways aerosol are presently observed could influence future treatment of aerosols in climate research. C1 Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Greenbelt, MD 20771 USA. Univ Ilorin, Dept Phys, Ilorin, Nigeria. RP Pinker, RT (reprint author), Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. EM pinker@atmos.umd.edu RI Dubovik, Oleg/A-8235-2009; Pinker, Rachel/F-6565-2010; OI Dubovik, Oleg/0000-0003-3482-6460; Pandithurai, G/0000-0001-7324-3773 NR 58 TC 36 Z9 36 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 16 PY 2001 VL 106 IS D19 BP 22923 EP 22930 DI 10.1029/2001JD900118 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 481UJ UT WOS:000171538600025 ER PT J AU Stone, EM Tabazadeh, A Jensen, E Pumphrey, HC Santee, ML Mergenthaler, JL AF Stone, EM Tabazadeh, A Jensen, E Pumphrey, HC Santee, ML Mergenthaler, JL TI Onset, extent, and duration of dehydration in the Southern Hemisphere polar vortex SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MICROWAVE LIMB SOUNDER; ANTARCTIC STRATOSPHERIC VORTEX; WATER-VAPOR; LIDAR OBSERVATIONS; HNO3 OBSERVATIONS; CLOUDS; AEROSOL; OZONE; UARS; WINTER AB Satellite observations of water vapor and aerosol extinction along with temperature trajectory calculations are analyzed for the Southern Hemisphere winter of 1992 in order to determine the onset, extent, and duration of dehydration within the polar vortex. Our investigation uses measurements of water vapor from the Microwave Limb Sounder (MLS) and aerosol extinction from the Cryogenic Limb Array Etalon Spectrometer (CLAES), both on board the Upper Atmosphere Research Satellite (UARS). Evidence of persistent ice cloud formation, supported by temperature statistics obtained from air parcel trajectories, suggests that the onset of the dehydration process occurs between late June and early July. By late August-early September water vapor depleted areas within the vortex no longer coincide with high aerosol extinctions, indicating that severe dehydration has occurred with the irreversible removal of water vapor over vast areas. Areas with depleted levels of water vapor, below the prewinter values, persist well into November. Evidence for dehydration is found on potential temperature surfaces from 420 K (the lower limit of the MLS measurements) to 520 K (approximately 16 to 22 km). The horizontal extent of the dehydrated area at 465 K encompasses up to 35% of the total vortex area equatorward of 80 degreesS. A comparison of CLAES aerosol extinction measurements and model calculations of aerosol extinction suggests an average ice particle number concentration and size of 10(-2)-10(-3) cm(-3) and 10-30 mum, respectively. We show that the difference between the timing of the onset of dehydration found here and that in a recent analysis of Polar Ozone and Aerosol Measurement III (POAM) observations can be explained by the latitudinal sampling pattern of the POAM instrument. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. Univ Edinburgh, Dept Meteorol, Edinburgh EH9 3JZ, Midlothian, Scotland. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Stone, EM (reprint author), ASML, Wilton, CT 06897 USA. EM emstone@snet.net; atabazadeh@mail.arc.nasa.gov NR 37 TC 10 Z9 10 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD OCT 16 PY 2001 VL 106 IS D19 BP 22979 EP 22989 DI 10.1029/2000JD000101 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 481UJ UT WOS:000171538600028 ER PT J AU Diskin, B AF Diskin, B TI Efficient multigrid methods for solving upwind-biased discretizations of the convection equation SO APPLIED MATHEMATICS AND COMPUTATION LA English DT Article DE convection operator; upwind-biased discretization; multigrid methods; semi-coarsening; characteristic components; textbook multigrid efficiency ID SOLVERS; FLOWS AB This paper studies a novel multigrid approach to the solution for a second-order upwind-biased discretization of the convection equation in two dimensions. This approach is based on semi-coarsening and well-balanced explicit correction terms, added to coarse-grid operators to maintain on coarse grids the same cross-characteristic interaction as on the target (fine) grid. Multicolor relaxation schemes are used on all the levels, allowing a very efficient parallel implementation. The results of the smoothing analysis and numerical tests can be summarized as follows: (1) The residual asymptotic convergence rate is about 3 per cycle, which far surpasses the theoretical limit (4/3) predicted for standard multigrid algorithms with full-coarsening. (2) The full multigrid (FMG) algorithm with two V(0, 2) cycles on the target grid and just one V(0, 2) cycle on all the coarse grids always provides an approximate solution with the algebraic error less than the discretization error, (3) A novel algorithm for deriving a discrete solution approximating the true continuous solution with a relative accuracy given in advance is developed. The computational complexity of this algorithm is (nearly) optimal (comparable with the complexity of the FMG algorithm applied to solve the problem on the optimally spaced target grid). (C) 2001 Elsevier Science Inc. All rights reserved. C1 NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. RP Diskin, B (reprint author), NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Mail Stop 132C, Hampton, VA 23681 USA. NR 23 TC 3 Z9 3 U1 1 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0096-3003 J9 APPL MATH COMPUT JI Appl. Math. Comput. PD OCT 15 PY 2001 VL 123 IS 3 BP 343 EP 379 DI 10.1016/S0096-3003(00)00073-4 PG 37 WC Mathematics, Applied SC Mathematics GA 468KP UT WOS:000170757100004 ER PT J AU Crucian, B Sams, C AF Crucian, B Sams, C TI Normal range assessment for 'fine' leukocyte subsets SO CYTOMETRY LA English DT Meeting Abstract C1 Wyle Labs, Houston, TX USA. NASA JSC, Houston, TX USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC, 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0196-4763 J9 CYTOMETRY JI Cytometry PD OCT 15 PY 2001 VL 46 IS 5 MA 9 BP 315 EP 315 PG 1 WC Biochemical Research Methods; Cell Biology SC Biochemistry & Molecular Biology; Cell Biology GA 487WW UT WOS:000171902900015 ER PT J AU Ching, WK Colussi, AJ Sun, HJ Nealson, KH Hoffmann, MR AF Ching, WK Colussi, AJ Sun, HJ Nealson, KH Hoffmann, MR TI Escherichia coli disinfection by electrohydraulic discharges SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Article ID HIGH-INTENSITY; PULSED ULTRASOUND; CHLORINE DIOXIDE; UV INACTIVATION; DRINKING-WATER; NUCLEIC-ACIDS; DNA; DAMAGE; DEGRADATION; PHOTOLYSIS AB We study the survival of single-strain Escherichia coli colonies in aqueous media exposed to 5.5 kV, 90 kA electrohydraulic discharges (EHD). The probability of survival (P-n) of a 4 x 10(7) cfu mL(-1) E. coli population after n consecutive EHDs follows a logit distribution: ln(Pd 100 - P-n) = 1.329 - 1.579 In n with r(2) = 0.993 that corresponds to lethal doses of LD50 = 2.2 and LD90 = 10.5 EHDs. Considering that the reactor is thoroughly mixed during each discharge and that LD50 = 0.9 values are nearly independent of E coli concentrations in the range of 2 x 10(3) less than or equal to E coli/cfu mL(-1) less than or equal to 3 x 10(6), we ascribe the nonexponential P-n decay of single-strain E coli colonies to a shielding phenomenon where inactive cells protect the successively smaller numbers of viable cells in the EHD. The qualitatively similar concentration dependence observed for survival under 254 nm of radiation, in contrast with the lower resistance of denser colonies to 20 kHz power ultrasound and the delayed onset of extracellular beta -D-galactosidase activity in bacterial populations already decimated by ENS, support the view that UV radiation is the dominant disinfection agent generated by electrohydraulic discharges. C1 CALTECH, WM Keck Labs, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hoffmann, MR (reprint author), CALTECH, WM Keck Labs, Pasadena, CA 91125 USA. RI Colussi, Agustin/C-6520-2008 NR 69 TC 33 Z9 36 U1 0 U2 10 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0013-936X J9 ENVIRON SCI TECHNOL JI Environ. Sci. Technol. PD OCT 15 PY 2001 VL 35 IS 20 BP 4139 EP 4144 DI 10.1021/es010643u PG 6 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA 481PG UT WOS:000171528100020 PM 11686378 ER PT J AU Potter, C Davidson, E Nepstad, D de Carvalho, CR AF Potter, C Davidson, E Nepstad, D de Carvalho, CR TI Ecosystem modeling and dynamic effects of deforestation on trace gas fluxes in Amazon tropical forests SO FOREST ECOLOGY AND MANAGEMENT LA English DT Article DE carbon; nitrogen; trace gas flux; Amazon forest; deforestation ID NET PRIMARY PRODUCTION; LAND-USE CHANGE; NITROUS-OXIDE; RAIN-FOREST; EASTERN AMAZONIA; BRAZILIAN AMAZON; BIOGEOCHEMICAL CONTROLS; SOLAR-RADIATION; CARBON-DIOXIDE; BOREAL FORESTS AB To improve predictive capabilities for water, carbon, and nitrogen gas fluxes in the Amazon region, we evaluated the performance of the NASA-CASA simulation model for tropical ecosystem biogeochemistry against independent flux measurements from two Amazon forest sites located in the Brazilian states of Rondonia and Para. Refinements of this ecosystem model include stand water balance equations, moisture holding and retention capacity for Amazon soils, and addition of a dynamic deforestation sequence to include land use change as a factor in simulations of tropical ecosystem fluxes. Results suggest that model predictions for evapotranspiration and soil water content are consistent with the overall range and seasonal changes in measured values at the two forest sites selected as test cases. The predicted carbon balance from the model implies that relatively undisturbed Amazon forest ecosystems may be large net sinks for atmospheric carbon, with annual net ecosystem production values on the order of 200 g C m(-2) per year. Measured fluxes of soil N2O for the two Amazon forests closely match our model prediction for the Para forest, but not for the Rondonia site, suggesting that process algorithms controlling nitrogen trace gas fluxes, particularly in relatively sandy tropical soils will require further study. In terms of net ecosystem carbon fluxes during deforestation and for 2 years afterward, the model predicts that these sites switch from being a net sink for carbon to a substantial source following the large loss of biomass from simulated burning. During crop regrowth simulation in the first year after deforestation, the net source of carbon to the atmosphere is nearly 1.6 kg C m(-2) per year, a flux magnitude roughly equivalent to 10 years of undisturbed CO2 sink fluxes in the Amazon forest. Compared to the primary forest that was cut and burned, predicted changes in soil nitrogen cycling lead to a doubling in annual emissions of N2O gas during the first year following deforestation, with lower emissions thereafter. Implications for scaling up these model predictions to the Amazon forest region are discussed with reference to necessary improvements in land cover, land use, and soils classifications for the area. Published by Elsevier Science B.V. C1 NASA, Ames Res Ctr, Ecosyst Sci & Technol Branch, Moffett Field, CA 94035 USA. Woods Hole Res Ctr, Woods Hole, MA 02543 USA. EMBRAPA, Amazonia Ocidental, Belem, Para, Brazil. RP Potter, C (reprint author), NASA, Ames Res Ctr, Ecosyst Sci & Technol Branch, Moffett Field, CA 94035 USA. RI Davidson, Eric/K-4984-2013 OI Davidson, Eric/0000-0002-8525-8697 NR 81 TC 28 Z9 31 U1 1 U2 17 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-1127 J9 FOREST ECOL MANAG JI For. Ecol. Manage. PD OCT 15 PY 2001 VL 152 IS 1-3 BP 97 EP 117 DI 10.1016/S0378-1127(00)00593-4 PG 21 WC Forestry SC Forestry GA 481BE UT WOS:000171497800008 ER PT J AU Holdren, DH Olsen, RO Schmidlin, FJ AF Holdren, DH Olsen, RO Schmidlin, FJ TI Comparison of total ozone overburden from handheld photometers with the Wallops Island Dobson spectrophotometer SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Total ozone column measurements are compared between the Dobson spectrophotometer located at Wallops Flight Facility, Wallops Island, VA, and two Microtops II photometers. The purpose of these comparisons is to determine whether the Microtops; II ozone measurements are comparable to those obtained with the Dobson spectrophotometer. Results have shown that the handheld photometer can provide measurements within about 2% of the Dobson's. A comparison between the two Microtops showed approximately a 3% difference in the derived ozone overburdens. Better results with the two Microtops were obtained using the 305.5-nm and the 312.5-nm filters only. C1 Sci & Engn Serv Inc, NASA, Goddard Space Flight Ctr, Wallops Isl, VA 23337 USA. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Wallops Isl, VA 23337 USA. RP Holdren, DH (reprint author), Sci & Engn Serv Inc, NASA, Goddard Space Flight Ctr, Code 972,Bldg N-159, Wallops Isl, VA 23337 USA. NR 4 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 15 PY 2001 VL 28 IS 20 BP 3859 EP 3862 DI 10.1029/2000GL011517 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 482RA UT WOS:000171588000009 ER PT J AU Chapron, B Vandemark, D Elfouhaily, T Thompson, DR Gaspar, P LaBroue, S AF Chapron, B Vandemark, D Elfouhaily, T Thompson, DR Gaspar, P LaBroue, S TI Altimeter sea state bias: A new look at global range error estimates SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ELECTROMAGNETIC BIAS; SURFACE; WAVES; SLOPE AB A nonparametric SSB model, derived using the TOPEX altimeter, is analyzed to show a new decomposition of the form SSB = bH(s) + f(sigma (o)), where b is 0.03 and the function of radar cross section (sigma (o)) is an absolute second-order range correction residing outside the conventional nondimensional SSB model. Expected variability in the dominant bH(s) term and its ties to the long wave orbital velocity and shorter-scale slope variances are discussed using a physic ally-motivated restatement of recent EM bias theory. The geometry of steep near-breaking waves, neglected within current theory, is invoked as one plausible explanation for the observed H(s)-independent SSB component. C1 IFREMER, Ctr Brest, F-29280 Plouzane, France. NASA, Goddard Space Flight Ctr, Wallops Isl, VA 23337 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA. Collecte Localisat Satellites, Ramonville St Agne, France. RP Chapron, B (reprint author), IFREMER, Ctr Brest, BP 70, F-29280 Plouzane, France. EM Bertrand.Chapron@ifremer.fr RI Chapron, Bertrand/O-6527-2015 NR 16 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 15 PY 2001 VL 28 IS 20 BP 3947 EP 3950 DI 10.1029/2001GL013346 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 482RA UT WOS:000171588000031 ER PT J AU Pan, JY Yan, XH Zheng, Q Liu, WT AF Pan, JY Yan, XH Zheng, Q Liu, WT TI Vector empirical orthogonal function modes of the ocean surface wind variability derived from satellite scatterometer data SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOUTHERN OSCILLATION; PACIFIC; GCM AB Ocean surface winds derived from NSCAT, QuikSCAT and ERS-1/2 scatterometer observations during a period from January 1992 to April 2000 were analyzed using the vector empirical orthogonal function (VEOF) method. With the boreal winter and summer oscillation, the first VEOF is dominated by the Indian and East Asian monsoons and also shows an annual cycle of the trade winds. The second VEOF represents the boreal autumn and spring oscillation, and reveals a transition state between winter and summer. The third VEOF indicates the wind variability associated with El Nino Southern Oscillation (ENSO) events, because the temporal mode has a high correlation coefficient of 0.8 with the Southern Oscillation Index (SOI). Further more, the third mode reveals the teleconnection of the Indian monsoon and wind variability over high latitude oceans', such as the Aleutian Low system, with ENSO events. C1 Univ Delaware, Grad Coll Marine Studies, Newark, DE 19716 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Ocean Univ Qingdao, Ocean Remote Sensing Inst, Qingdao 266003, Peoples R China. RP Yan, XH (reprint author), Univ Delaware, Grad Coll Marine Studies, Newark, DE 19716 USA. RI Zheng, Quanan/F-9025-2010 NR 11 TC 6 Z9 8 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD OCT 15 PY 2001 VL 28 IS 20 BP 3951 EP 3954 DI 10.1029/2001GL013060 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 482RA UT WOS:000171588000032 ER PT J AU Gim, Y Kleinsasser, AW Barner, JB AF Gim, Y Kleinsasser, AW Barner, JB TI Current injection into high temperature superconductors: Does spin matter? SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID DYNAMIC PAIR-BREAKING; POLARIZED CURRENT; HETEROSTRUCTURES; DEVICES; FERROMAGNET; JUNCTIONS; FILMS; MAGNETORESISTANCE; SUPPRESSION AB Recent comparative studies of quasiparticle injection from colossal magnetoresistance (CMR) materials and normal metals into high transition temperature superconductors (HTS) have led several investigators to conclude that spin-polarized injection from CMR electrodes is far more efficient than ordinary injection in suppressing superconductivity. On the other hand, some ordinary quasiparticle injection experiments have shown greater suppression of superconductivity than was claimed in any of the published spin-injection experiments. Careful analysis and numerical simulations lead us to argue that all spin-injection experiments to date have been hampered by inadequate control samples and that the reported results can be explained by ordinary (unpolarized) quasiparticle injection or simple current summation. We conclude that there is no conclusive evidence that spin-polarized injection into HTS behaves differently from ordinary quasiparticle injection and we discuss criteria for future experiments that could differentiate between the two types of injection. (C) 2001 American Institute of Physics. C1 CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. RP Gim, Y (reprint author), CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 32 TC 56 Z9 58 U1 1 U2 3 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD OCT 15 PY 2001 VL 90 IS 8 BP 4063 EP 4077 DI 10.1063/1.1404427 PG 15 WC Physics, Applied SC Physics GA 482EP UT WOS:000171562100057 ER PT J AU Egbert, GD Ray, RD AF Egbert, GD Ray, RD TI Estimates of M-2 tidal energy dissipation from TOPEX/Poseidon altimeter data SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID GLOBAL OCEAN TIDES; INTERNAL TIDES; DEEP-OCEAN; SURFACE MANIFESTATION; SATELLITE ALTIMETRY; ABYSSAL OCEAN; SOLID EARTH; MODELS; COMPUTATIONS; DEFORMATION AB Most of the tidal energy dissipation in the ocean occurs in shallow seas, as has long been recognized. However, recent work has suggested that a significant fraction of the dissipation, perhaps 1 TW or more, occurs in the deep ocean. This paper builds further evidence for that conclusion. More than 6 years of data from the TOPEX/Poseidon satellite altimeter are used to map the tidal dissipation rate throughout the world ocean. The dissipation rate is estimated as a balance between the rate of working by tidal forces and the energy flux divergence, computed using currents derived by least squares fitting of the altimeter data and the shallow water equations. Such calculations require dynamical assumptions, in particular about the nature of dissipation. To assess sensitivity of dissipation estimates to input assumptions, a large suite of tidal inversions based on a wide range of drag parameterizations and employing both real arid synthetic altimeter data are compared. These experiments and Monte Carlo error fields from a generalized inverse model are used to establish error uncertainties for the dissipation estimates. Owing to the tight constraints on tidal elevation fields provided by the altimeter, area integrals of the energy balance are remarkably insensitive to required dynamical assumptions. Tidal energy dissipation is estimated for all major shallow seas (excluding individual polar seas) and compared with previous model and data-based estimates. Dissipation in the open ocean is significantly enhanced around major bathymetric features; in a manner consistent with simple theories for the generation of baroclinic tides. C1 Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Oregon State Univ, Coll Ocean & Atmospher Sci, Ocean Adm Bldg 104, Corvallis, OR 97331 USA. EM egbert@oce.orst.edu; richard.ray@gsfc.nasa.gov RI Ray, Richard/D-1034-2012; OI Egbert, Gary/0000-0003-1276-8538 NR 79 TC 181 Z9 189 U1 4 U2 21 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9275 EI 2169-9291 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD OCT 15 PY 2001 VL 106 IS C10 BP 22475 EP 22502 DI 10.1029/2000JC000699 PG 28 WC Oceanography SC Oceanography GA 480NR UT WOS:000171468300026 ER PT J AU DiGiacomo, PM Holt, B AF DiGiacomo, PM Holt, B TI Satellite observations of small coastal ocean eddies in the Southern California Bight SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Review ID SYNTHETIC-APERTURE RADAR; SANTA-BARBARA CHANNEL; SPIN-OFF EDDIES; SIR-C/X-SAR; MESOSCALE EDDIES; SEA-SURFACE; POINT CONCEPTION; CURRENT SYSTEM; EDDY FORMATION; STATISTICAL-ANALYSIS AB This study describes the characteristics of extensive small-scale coastal ocean eddies in the Southern California Bight. These surface features were primarily detected by using ERS-1 and ERS-2 synthetic aperture radar (SAR) satellite imagery from 1992 to 1998. The eddies, predominantly cyclonic in their rotation, appeared to result from several forcing mechanisms. They were mainly observed within the Santa Barbara Channel and the Santa Monica-San Pedro Basin regions and appeared to be seasonal in their distribution. Observed eddy diameters were all less than 50 km, with over 70% less than 10 km. The SAR data were complemented by sea surface temperature measurements derived from advanced very high resolution radiometer satellite imagery, as well as in situ data from moorings and drifters that provided substantial verification of the small-scale eddies. These findings are significant in that the eddies were, in general, smaller in size and more abundant than previously reported. Additionally, these results provide further evidence of the complex near-surface circulation within the Southern California Bight, with important implications far nutrient flux, productivity, plankton patchiness, larval transport and recruitment, and dispersal of pollutants. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP DiGiacomo, PM (reprint author), CALTECH, Jet Prop Lab, M-S 300-323,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI DiGiacomo, Paul/F-5584-2010 OI DiGiacomo, Paul/0000-0003-4550-1899 NR 104 TC 81 Z9 84 U1 1 U2 17 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD OCT 15 PY 2001 VL 106 IS C10 BP 22521 EP 22543 DI 10.1029/2000JC000728 PG 23 WC Oceanography SC Oceanography GA 480NR UT WOS:000171468300028 ER PT J AU Cassen, P AF Cassen, P TI Unresolved questions regarding the origins of Solar System solids SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article DE solar nebula; planets; meteorites; elemental composition; isotopic composition ID ALUMINUM-RICH INCLUSIONS; CHONDRITES; NEBULA; RADIOACTIVITIES; FRACTIONATION; METEORITES; ABUNDANCES; CLOUD; RAYS AB It is remarkable that we possess samples of Solar System solids which have retained a record of galactic and stellar events that occurred well before the birth of the Sun, as well as samples which contain evidence of Solar System processes that occurred during the earliest stages of planet building. The signatures of such processes are most commonly recognized in isotopic anomalies, identifiable against a pervasive background of isotopic homogeneity, and systematic trends in the elemental abundance patterns of primitive meteoritic materials. Although the significance of these anomalies and patterns is unmistakable, their interpretation in terms of specific processes is problematic. Central to such interpretations are questions of spatial scale: do cosmogonically significant isotopic and elemental compositions reflect processes that occurred on the grand scale of the proto-solar cloud, or do they result from many localized events within a nebular or planetary environment? The question is fundamental to our understanding of the formation of solid objects in the Solax System. This question will be examined here, with specific reference to theoretical models of nebular evolution and planet building, and evidence regarding the survival of presolar signatures, the origin of short-lived radionuclides and oxygen isotopic systematics. C1 SETI Inst, Mt View, CA 94043 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Cassen, P (reprint author), SETI Inst, 2035 Landings Dr, Mt View, CA 94043 USA. NR 45 TC 2 Z9 2 U1 0 U2 1 PU ROYAL SOC LONDON PI LONDON PA 6 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 1364-503X J9 PHILOS T ROY SOC A JI Philos. Trans. R. Soc. Lond. Ser. A-Math. Phys. Eng. Sci. PD OCT 15 PY 2001 VL 359 IS 1787 BP 1935 EP 1946 PG 12 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 482EZ UT WOS:000171563900002 ER PT J AU Lugmair, G Lee, T Russell, SS Gounelle, M Turner, G Hartmann, L Ash, R Cassen, P AF Lugmair, G Lee, T Russell, SS Gounelle, M Turner, G Hartmann, L Ash, R Cassen, P TI Origin of short-lived radionuclides - Discussion SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Editorial Material C1 Max Planck Inst Chem, Mainz, Germany. Acad Sinica, Inst Earth Sci, Taipei 115, Taiwan. Univ Manchester, Dept Geol Sci, Manchester M13 9PL, Lancs, England. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Oxford, Dept Earth Sci, Oxford OX1 2JD, England. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Lugmair, G (reprint author), Max Planck Inst Chem, Mainz, Germany. RI Lee, Typhoon/N-8347-2013 NR 1 TC 0 Z9 0 U1 0 U2 0 PU ROYAL SOC LONDON PI LONDON PA 6 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 1364-503X J9 PHILOS T ROY SOC A JI Philos. Trans. R. Soc. Lond. Ser. A-Math. Phys. Eng. Sci. PD OCT 15 PY 2001 VL 359 IS 1787 BP 2003 EP 2004 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 482EZ UT WOS:000171563900011 ER PT J AU Bridges, JC Young, ED Ash, R Allegre, C Cassen, P AF Bridges, JC Young, ED Ash, R Allegre, C Cassen, P TI The hydrology of carbonaceous chondrite parent bodies and the evolution of planet progenitors - Discussion SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Editorial Material C1 Nat Hist Museum, London SW7 5BD, England. Univ Oxford, Dept Earth Sci, Oxford OX1 2JD, England. Inst Phys Globe, Paris, France. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bridges, JC (reprint author), Nat Hist Museum, Cromwell Rd, London SW7 5BD, England. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ROYAL SOC LONDON PI LONDON PA 6 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND SN 1364-503X J9 PHILOS T ROY SOC A JI Philos. Trans. R. Soc. Lond. Ser. A-Math. Phys. Eng. Sci. PD OCT 15 PY 2001 VL 359 IS 1787 BP 2109 EP 2110 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 482EZ UT WOS:000171563900024 ER PT J AU Albuquerque, IFM Hui, L Kolb, EW AF Albuquerque, IFM Hui, L Kolb, EW TI High energy neutrinos from superheavy dark matter annihilation SO PHYSICAL REVIEW D LA English DT Article ID INTERACTING MASSIVE PARTICLES; COSMIC-RAYS; RELIC PARTICLES; NEUTRON-STARS; INFLATION; UNIVERSE; BREAKING; LIMITS; WINDOW; EARTH AB Superheavy (M> 10(10)) GeV) particles produced during inflation may be the dark matter. independent of their interaction strength. Strongly interacting superheavy particles will be captured by the Sun. and their annihilation in the center of the Sun will produce a flux of energetic neutrinos that should be detectable by neutrino telescopes, Depending on the particle mass, event rates in a cubic-kilometer detector range from several per hour to several per year. The signature of the process is a predominance of tau neutrinos. with a relatively flat energy spectrum of events ranging from 50 GeV to many TeV, and with the mean energy of detected tau neutrinos about 3 TeV. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Princeton Univ Sch Nat Sci, Inst Adv Study, Princeton, NJ 08540 USA. Columbia Univ, Dept Phys, New York, NY 10027 USA. Fermilab Natl Accelerator Lab, NASA, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. EM ifreire@fnal.gov; lhui@ias.edu; rocky@fnal.gov RI Albuquerque, Ivone/H-4645-2012 OI Albuquerque, Ivone/0000-0001-7328-0136 NR 33 TC 28 Z9 28 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0010 EI 2470-0029 J9 PHYS REV D JI Phys. Rev. D PD OCT 15 PY 2001 VL 64 IS 8 AR 083504 DI 10.1103/PhysRevD.64.083504 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 483UR UT WOS:000171654700017 ER PT J AU Stiff, D Widrow, LM Frieman, J AF Stiff, D Widrow, LM Frieman, J TI Signatures of hierarchical clustering in dark matter detection experiments SO PHYSICAL REVIEW D LA English DT Article ID GALACTIC HALO; MILKY-WAY; SECONDARY INFALL; GALAXY FORMATION; MERGING HISTORY; MODELS; UNIVERSE; MASS; SENSITIVITY; ACCRETION AB In the cold dark matter model of structure formation, galaxies are assembled hierarchically from mergers and the accretion of subclumps. This process is expected to leave residual substructure in the galactic dark halo, including partially disrupted clumps and their associated tidal debris. We develop a model for such halo substructure and study its implications for dark matter (WIMP and axion) detection experiments. We combine the Press-Schechter model for the distribution of halo subclump masses with N-body simulations of the evolution and disruption of individual clumps as they orbit through the evolving Galaxy to derive the probability that the Earth is passing through a subclump or stream of a given density. Our results suggest that it is likely that the local complement of dark matter particles includes a 1-5 % contribution from a single clump. The implications for dark matter detection experiments are significant, since the disrupted clump is composed of a "cold" flow of high-velocity particles. We describe the distinctive features due to halo clumps that would be seen in the energy and angular spectra of detection experiments. The annual modulation of these features would have a different signature and phase from that for a smooth halo and. in principle. would allow one to discern the direction of motion of the clump relative to the galactic center. C1 Queens Univ, Dept Phys, Kingston, ON K7L 3N6, Canada. NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Stiff, D (reprint author), Queens Univ, Dept Phys, Kingston, ON K7L 3N6, Canada. NR 65 TC 51 Z9 51 U1 1 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD OCT 15 PY 2001 VL 64 IS 8 AR 083516 DI 10.1103/PhysRevD.64.083516 PG 16 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 483UR UT WOS:000171654700029 ER PT J AU Riess, AG Nugent, PE Gilliland, RL Schmidt, BP Tonry, J Dickinson, M Thompson, RI Budavari, T Casertano, S Evans, AS Filippenko, AV Livio, M Sanders, DB Shapley, AE Spinrad, H Steidel, CC Stern, D Surace, J Veilleux, S AF Riess, AG Nugent, PE Gilliland, RL Schmidt, BP Tonry, J Dickinson, M Thompson, RI Budavari, T Casertano, S Evans, AS Filippenko, AV Livio, M Sanders, DB Shapley, AE Spinrad, H Steidel, CC Stern, D Surace, J Veilleux, S TI The farthest known supernova: Support for an accelerating universe and a glimpse of the epoch of deceleration SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; supernovae : general ID HUBBLE DEEP FIELD; GAMMA-RAY BURST; HIGH-REDSHIFT SUPERNOVAE; 25 APRIL 1998; IA SUPERNOVAE; LIGHT CURVES; OPTICAL-SPECTRA; STAR-FORMATION; COSMOLOGICAL PARAMETERS; PHOTOMETRIC REDSHIFTS AB We present photometric observations of an apparent Type Ia supernova (SN Ia) at a redshift of similar to1.7, the farthest SN observed to date. The supernova, SN 1997ff, was discovered in a repeat observation by the Hubble Space Telescope (HST) of the Hubble Deep Field-North (HDF-N) and serendipitously monitored with NICMOS on HST throughout the Thompson et al. Guaranteed-Time Observer (GTO) campaign. The SN type can be determined from the host galaxy type : an evolved, red elliptical lacking enough recent star formation to provide a significant population of core-collapse supernovae. The classification is further supported by diagnostics available from the observed colors and temporal behavior of the SN, both of which match a typical SN Ia. The photometric record of the SN includes a dozen flux measurements in the I, J, and H bands spanning 35 days in the observed frame. The redshift derived from the SN photometry, z = 1.7 +/- 0.1, is in excellent agreement with the redshift estimate of z = 1.65 +/- 0.15 derived from U(300) B(450) V(606) I(814) J(110) J(125) H(160) H(165) K(s) photometry of the galaxy. Optical and near-infrared spectra of the host provide a very tentative spectroscopic redshift of 1.755. Fits to observations of the SN provide constraints for the redshift-distance relation of SNe Ia and a powerful test of the current accelerating universe hypothesis. The apparent SN brightness is consistent with that expected in the decelerating phase of the preferred cosmological model, Omega (M) approximate to 1/3, Omega (Lambda) approximate to 2/3. It is inconsistent with gray dust or simple luminosity evolution, candidate astrophysical effects that could mimic previous evidence for an accelerating universe from SNe Ia at z approximate to 0.5. We consider several sources of potential systematic error, including gravitational lensing, supernova misclassification, sample selection bias, and luminosity calibration errors. Currently, none of these effects alone appears likely to challenge our conclusions. Additional SNe Ia at z > 1 will be required to test more exotic alternatives to the accelerating universe hypothesis and to probe the nature of dark energy. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. Mt Stromlo & Siding Spring Observ, Weston 2611, Australia. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Eotvos Lorand Univ, Dept Phys, H-1518 Budapest, Hungary. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, SIRTF Sci Ctr, Pasadena, CA 91125 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Riess, AG (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. EM ariess@stsci.edu OI Schmidt, Brian/0000-0001-6589-1287 NR 100 TC 577 Z9 582 U1 1 U2 13 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2001 VL 560 IS 1 BP 49 EP 71 DI 10.1086/322348 PN 1 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 482QT UT WOS:000171587300006 ER PT J AU Terashima, Y Wilson, AS AF Terashima, Y Wilson, AS TI A Chandra observation of M51: Active nucleus and nuclear outflows SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (M51); galaxies : nuclei; galaxies : Seyfert; shock waves; X-rays : galaxies ID X-RAY-SPECTRA; GALAXIES; ASCA; NGC-5195; EMISSION; SHOCKS AB We present a Chandra Advanced CCD Imaging Spectrometer (ACIS-S) observation of the nuclear region of the nearby spiral galaxy M51 (NGC 5194), which has a low-luminosity Seyfert 2 nucleus. The X-ray image shows the nucleus, southern extranuclear cloud, and northern loop, the morphology of the extended emission being very similar to those seen in radio continuum and optical emission-line images. The X-ray spectrum of the nucleus is well represented by a model consisting of soft thermal plasma with kT approximate to 0.5 keV, a very hard continuum, and an Fe K alpha emission line at 6.45 keV with an equivalent width of greater than 2 keV. The very strong Fe line and the flat continuum indicate that the nucleus is obscured by a column density in excess of 10(24) cm(-2) and that the spectrum is dominated by reflected emission from cold matter near the nucleus. The X-ray spectra of the extranuclear clouds are well fitted by a thermal plasma model with kT approximate to 0.5 keV. This spectral shape and morphology strongly suggest that the clouds are shock-heated by the bipolar outflow from the nucleus. The shock velocities of the extranuclear cloud and northern loop inferred from the temperatures of the X-ray gas are 690 and 660 km s(-1), respectively. By assuming a steady state situation in which the emission of the extranuclear clouds is powered by the jets, the mechanical energy in the jets is found to be comparable to the bolometric luminosity of the nucleus. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Terashima, Y (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 28 TC 44 Z9 45 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2001 VL 560 IS 1 BP 139 EP 144 DI 10.1086/321615 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 482QT UT WOS:000171587300014 ER PT J AU Oegerle, WR Cowie, L Davidsen, A Hu, E Hutchings, J Murphy, E Sembach, K Woodgate, B AF Oegerle, WR Cowie, L Davidsen, A Hu, E Hutchings, J Murphy, E Sembach, K Woodgate, B TI FUSE observations of cooling-flow gas in the galaxy clusters A1795 and A2597 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cooling flows; galaxies : clusters : individual (Abell 1795, Abell 2597); intergalactic medium; ultraviolet : galaxies ID RAY-LUMINOUS CLUSTERS; IMAGING OBSERVATIONS; EMISSION-LINES; RADIO GALAXY; CD-GALAXY; DUST; CORES; EXTINCTION; ABELL-2597; ABELL-1795 AB We present far-ultraviolet spectroscopy of the cores of the massive cooling-flow clusters Abell 1795 and 2597, obtained with the Far Ultraviolet Spectroscopic Explorer. As the intracluster gas cools through 3 x 10(5) K, it should emit strongly in the O VI lambda lambda 1032, 1038 resonance lines. We report the detection of O VI lambda 1032 emission in A2597, with a line flux of (1.35 +/- 0.35) x 10(-15) ergs cm(-2) s(-1), as well as detection of emission from C III lambda 977. A marginal detection of C III lambda 977 emission is also reported for A1795. These observations provide evidence for a direct link between the hot (10(7) K) cooling-flow gas and the cool (10(4) K) gas in the optical emission line filaments. Assuming simple cooling-flow models, the O VI line flux in A2597 corresponds to a mass deposition rate of similar to 40 M-. y(-1) within the central 36 kpc. Emission from O VI j1032 was not detected in A1795, with an upper limit of 1.5 x 10(-15) ergs cm(-2) s(-1), corresponding to a limit on the mass cooling-flow rate of (M) over dot (28 kpc) <28 M-. yr(-1). We have considered several explanations for the lack of detection of O VI emission in A1795 and the weaker than expected flux in A2597, including extinction by dust in the outer cluster and quenching of thermal conduction by magnetic fields. We conclude that a turbulent mixing model, with some dust extinction, could explain our O VI results while also accounting for the puzzling lack of emission by Fe XVII in cluster cooling flows. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. HIA NRC Canada, Dominion Astrophys Observ, Victoria, BC V9E 2E7, Canada. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. RP Oegerle, WR (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. RI Oegerle, William/C-9070-2012 NR 51 TC 43 Z9 43 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2001 VL 560 IS 1 BP 187 EP 193 DI 10.1086/322246 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 482QT UT WOS:000171587300019 ER PT J AU Bakes, ELO Tielens, AGGM Bauschlicher, CW Hudgins, DM Allamandola, LJ AF Bakes, ELO Tielens, AGGM Bauschlicher, CW Hudgins, DM Allamandola, LJ TI Theoretical modeling of infrared emission from neutral and charged polycyclic aromatic hydrocarbons. II. SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : lines and bands; ISM : molecules; infrared : ISM; methods : analytical; molecular processes ID INTERSTELLAR DUST; SPECTRA; CATIONS; SPECTROSCOPY; NAPHTHALENE; MOLECULES; FEATURES; GRAINS; FREQUENCIES; EXTINCTION AB The nature of the carriers of the interstellar infrared (IR) emission features between 3.3 and 12.7 mum is complex. We must consider emission from a family of polycyclic aromatic hydrocarbons (PAHs) in a multiplicity of cationic charge states (+1, +2, +3, and so on), along with neutral and anionic PAHs. The adopted intrinsic IR cross sections of the various modes of the PAHs are the key to all models. Here we make a comparison between laboratory-measured cross sections and quantum chemical calculations and find that, overall, the agreement is very good. In this paper, we consider emission from a wide variety of specific PAH molecules, which includes all available data from our laboratory and quantum chemical databases. We incorporate this into our model to produce a theoretical analysis that is more realistic, detailed, and comprehensive than prior studies. PAH molecular structures that we consider include symmetric condensed, symmetric noncondensed, aromatics containing pentagonal rings, linear, and methylated PAHs. The synthesized IR spectra show large variations in peak position for the small PAHs studied, while their spectral profile is uniquely characteristic of each different molecular structure. We also investigate the spectral variations with molecular structure of a PAH population at the surface of the Orion photodissociation region (PDR) and include an example of how the IR spectrum of our PAH population varies dramatically as a function of depth (or radiation field) through the PDR. We make a comparison of these results with Infrared Space Observatory data measured at the surface of the Orion PDR. We conclude that the charge of PAHs in a composite population has a stronger effect on its IR emission spectrum than its molecular structure. However, on the basis of the PAH samples considered in this paper, detailed studies of the interstellar IR emission features can be used effectively to identify molecular characteristics of the interstellar PAH family. In Paper III, we extend the theme of this paper by investigating the effects of hydrogenation on a wide variety of PAHs up to size 54 carbon atoms and compare our results with observational profiles for the Orion PDR. C1 NASA, SETI Inst, Ames Res Ctr, Moffett Field, CA 94035 USA. Kapteyn Astron Inst, SRON, NL-9700 AV Groningen, Netherlands. RP Bakes, ELO (reprint author), NASA, SETI Inst, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 32 TC 49 Z9 49 U1 1 U2 11 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2001 VL 560 IS 1 BP 261 EP 271 DI 10.1086/322769 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 482QT UT WOS:000171587300027 ER PT J AU Kaspi, VM Roberts, ME Vasisht, G Gotthelf, EV Pivovaroff, M Kawai, N AF Kaspi, VM Roberts, ME Vasisht, G Gotthelf, EV Pivovaroff, M Kawai, N TI Chandra X-ray observations of G11.2-0.3: Implications for pulsar ages SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : general; pulsars : individual (AX J1811.5-1926; PSR J1811-1925); supernovae : individual (G11.2-0.3); X-rays : general ID SUPERNOVA REMNANT G11.2-0.3; SPIN-DOWN; RADIO PULSARS; NEUTRON-STARS; VELA PULSAR; DISCOVERY; STATISTICS; VELOCITIES; EVOLUTION; POPULATION AB We present Chandra X-Ray Observatory imaging observations of the young Galactic supernova remnant G11.2-0.3. The image shows that the previously known young 65 ms X-ray pulsar is at position (J2000) R.A. 18(h)11(m)29(s).22, decl. -19 degrees 25'27 " .6, with 1 sigma error radius of 0."6. This is within 8 " of the geometric center of the shell. This provides strong confirming evidence that the system is younger, by a factor of similar to 12, than the characteristic age of the pulsar. The age discrepancy suggests that pulsar characteristic ages can be poor age estimators for young pulsars. Assuming conventional spin-down with constant magnetic field and braking index, the most likely explanation for the age discrepancy in G11.2-0.3 is that the pulsar was born with a spin period of similar to 62 ms. The Chandra image also reveals, for the first time, the morphology of the pulsar wind nebula. The elongated hard X-ray structure can be interpreted as either a jet or a Crab-like torus seen edge-on. This adds to the growing list of highly aspherical pulsar wind nebulae and argues that such structures are common around young pulsars. C1 McGill Univ, Dept Phys, Montreal, PQ H3A 2T8, Canada. MIT, Dept Phys, Cambridge, MA 02139 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Columbia Univ, Dept Astron, New York, NY 10027 USA. Therma Wave Inc, Fremont, CA 94539 USA. Tokyo Inst Technol, Dept Phys, Meguro Ku, Tokyo 1528551, Japan. Inst Phys & Chem Res, Wako, Saitama 3510198, Japan. RP Kaspi, VM (reprint author), McGill Univ, Dept Phys, Rutherford Phys Bldg,3600 Univ St, Montreal, PQ H3A 2T8, Canada. RI Pivovaroff, Michael/M-7998-2014; OI Pivovaroff, Michael/0000-0001-6780-6816; Roberts, Mallory/0000-0002-9396-9720 NR 55 TC 74 Z9 75 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2001 VL 560 IS 1 BP 371 EP 377 DI 10.1086/322515 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 482QT UT WOS:000171587300035 ER PT J AU Finger, MH Macomb, DJ Lamb, RC Prince, TA Coe, MJ Haigh, NJ AF Finger, MH Macomb, DJ Lamb, RC Prince, TA Coe, MJ Haigh, NJ TI Discovery of pulsed X-rays from the SMC transient RX J0052.1-7319 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : general; pulsars : individual (RX J0052.1-7319); X-rays : stars ID SMALL-MAGELLANIC-CLOUD; BINARY-SYSTEMS; OUTBURST; J0117.6-7330; POPULATIONS; EMISSION AB Coherent 65 mHz pulsations in the X-ray flux of the Small Magellanic Cloud (SMC) transient source RX J0052.1-7319 have been detected by us in an analysis of ROSAT data. We report on the pulsations we detected in ROSAT HRI data and simultaneous detection of these pulses in hard X-rays using BATSE data. The BATSE data show an outburst of the source lasting 60 days. We report on optical observations of the candidate companion, and a new source position we determined from the HRI data, which is consistent with the candidate's location. From the measured fluxes and observed frequency derivatives we exclude the possibility that the pulsar is in the foreground of the SMC and show that an accretion disk is present during the outburst, which peaked near Eddington luminosity. C1 Natl Space Sci & Technol Ctr, ES 50, Huntsville, AL 35805 USA. NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. CALTECH, Space Radiat Lab, Pasadena, CA 91125 USA. Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. RP Finger, MH (reprint author), Univ Space Res Assoc, Astrophys Programs, Columbia, MD 21044 USA. NR 31 TC 8 Z9 8 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2001 VL 560 IS 1 BP 378 EP 383 DI 10.1086/322484 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 482QT UT WOS:000171587300036 ER PT J AU Djorgovski, SG Castro, S Stern, D Mahabal, AA AF Djorgovski, SG Castro, S Stern, D Mahabal, AA TI On the threshold of the reionization epoch SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : formation; quasars : individual (SDSS 1044-0125) ID HIGH-REDSHIFT QUASARS; GUNN-PETERSON TROUGH; DIGITAL SKY SURVEY; COSMOLOGICAL REIONIZATION; UNIVERSE; GALAXIES AB Discovery of the cosmic reionization epoch would represent a significant milestone in cosmology. We present Keck spectroscopy of the quasar SDSS 1044 similar to 0125, at z = 5.73,. The spectrum shows a dramatic increase in the optical depth at observed wavelengths lambda greater than or similar to 7550 Angstrom, corresponding to z(abs) greater than or similar to 5.2. Only a few small, narrow transmission regions are present in the spectrum beyond that point and out to the redshifts where the quasar signal begins. We interpret this result as a signature of the trailing edge of the cosmic reionization epoch, which we estimate to occur around 6 (as indeed confirmed by subsequent observations by Becker et al.) and extending down to z similar to 5.2. This behavior is expected in the modern theoretical models of the reionization era, which predict a patchy and gradual onset of reionization. The remaining transmission windows we see may correspond to the individual reionization bubbles (Stromgren spheres) embedded in a still largely neutral intergalactic medium, intersected by the line of sight to the quasar. Future spectroscopic observations of quasars at comparable or larger redshifts will provide a more detailed insight into the structure and extent of the reionization era. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Djorgovski, SG (reprint author), CALTECH, Palomar Observ, 105-24, Pasadena, CA 91125 USA. NR 29 TC 100 Z9 100 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2001 VL 560 IS 1 BP L5 EP L8 DI 10.1086/324175 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 482RF UT WOS:000171588500002 ER PT J AU Nordstrom, J Carpenter, MH AF Nordstrom, J Carpenter, MH TI High-order finite difference methods, multidimensional linear problems, and curvilinear coordinates SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID NAVIER-STOKES EQUATIONS; STABLE PENALTY METHOD; DOMAIN DECOMPOSITION SCHEMES; BOUNDARY-CONDITIONS; EULER EQUATIONS; SUMMATION; PARTS; APPROXIMATIONS; PROJECTIONS; STABILITY AB Boundary and interface conditions are derived for high-order finite difference methods applied to multidimensional linear problems in curvilinear coordinates. Difficulties presented by the combination of multiple dimensions and varying coefficients are analyzed. In particular, problems related to nondiagonal norms, a varying Jacobian, and varying and vanishing wave speeds are considered. The boundary and interface conditions lead to conservative schemes and strict and strong stability provided that certain metric conditions are met. (C) 2001 Academic Press. C1 Swedish Def Res Agcy, Aerodynam Div, Comp Aerodynam Dept, Uppsala, Sweden. Univ Uppsala, Dept Sci Comp Informat Technol, Uppsala, Sweden. NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. RP Nordstrom, J (reprint author), Swedish Def Res Agcy, Aerodynam Div, Comp Aerodynam Dept, Uppsala, Sweden. OI Nordstrom, Jan/0000-0002-7972-6183 NR 33 TC 68 Z9 71 U1 2 U2 8 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD OCT 10 PY 2001 VL 173 IS 1 BP 149 EP 174 DI 10.1006/jcph.2001.6864 PG 26 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 481YD UT WOS:000171547300006 ER PT J AU Zimmermann, S Koumoutsakos, P Kinzelbach, W AF Zimmermann, S Koumoutsakos, P Kinzelbach, W TI Simulation of pollutant transport using a particle method SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE diffusion; particle methods ID CONVECTION-DIFFUSION EQUATIONS; VORTEX; VISCOSITY AB A Lagrangian scheme is presented for the two-dimensional simulation or pollutant transport in a porous medium. The anisotropic extension of the particle strength exchange method is implemented to describe the diffusive-dispersive process. By applying the scheme to a benchmark problem with an analytical solution, the method is shown to be accurate and stable even in the limiting cases of vanishing diffusion-dispersion coefficients and high anisotropy ratios. The scheme is shown to perform well with spatially variable velocity fields also. (C) 2001 Academic Press. C1 ETH Honggerberg, Inst Hydromech & Water Resources Mamagement, CH-8093 Zurich, Switzerland. ETH Zurich, Inst Computat Sci, CH-8092 Zurich, Switzerland. NASA, CTR, Moffett Field, CA 94035 USA. RP Zimmermann, S (reprint author), ETH Honggerberg, Inst Hydromech & Water Resources Mamagement, CH-8093 Zurich, Switzerland. RI Koumoutsakos, Petros/A-2846-2008 OI Koumoutsakos, Petros/0000-0001-8337-2122 NR 24 TC 20 Z9 20 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD OCT 10 PY 2001 VL 173 IS 1 BP 322 EP 347 DI 10.1006/jcph.2001.6879 PG 26 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 481YD UT WOS:000171547300014 ER EF