FN Thomson Reuters Web of Science™ VR 1.0 PT J AU DiLella, D Whitman, LJ Colton, RJ Kenny, TW Kaiser, WJ Vote, EC Podosek, JA Miller, LM AF DiLella, D Whitman, LJ Colton, RJ Kenny, TW Kaiser, WJ Vote, EC Podosek, JA Miller, LM TI A micromachined magnetic-field sensor based on an electron tunneling displacement transducer SO SENSORS AND ACTUATORS A-PHYSICAL LA English DT Article DE magnetic-field sensor; tunnel sensor; MEMS ID SURFACE-DIFFUSION; FORCE MICROSCOPY; MAGNETOMETER; DETECTOR; PROPOSAL; AU(111); VACUUM; SCALE; GOLD AB We describe a micromachined magnetic-field sensor that is based on an electron tunneling transducer. This tunnel sensor is small, very sensitive, operates at ambient temperature and requires very little power. The measured resolution of the sensor is 0.3 nT/root Hz at 1 Hz, The limiting resolution, calculated based on fundamental noise sources, is 0.002 nT/root Hz at 1 Hz. The dominant source of the observed noise in the present device is low frequency air pressure fluctuations. (C) 2000 Published by Elsevier Science B.V. C1 USN, Res Lab, Washington, DC 20375 USA. CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. RP DiLella, D (reprint author), Shepherd Coll, Dept Chem, Shepherdstown, WV 25443 USA. RI Whitman, Lloyd/G-9320-2011 OI Whitman, Lloyd/0000-0002-3117-1174 NR 34 TC 23 Z9 30 U1 1 U2 9 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0924-4247 J9 SENSOR ACTUAT A-PHYS JI Sens. Actuator A-Phys. PD OCT 30 PY 2000 VL 86 IS 1-2 BP 8 EP 20 DI 10.1016/S0924-4247(00)00303-4 PG 13 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 368PY UT WOS:000090127700002 ER PT J AU Chin, M Rood, RB Lin, SJ Muller, JF Thompson, AM AF Chin, M Rood, RB Lin, SJ Muller, JF Thompson, AM TI Atmospheric sulfur cycle simulated in the global model GOCART: Model description and global properties SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; DRY DEPOSITION; GAS-EXCHANGE; TRANSPORT; PARAMETERIZATION; DIMETHYLSULFIDE; EMISSIONS; DATASET; PREDICTION; CHEMISTRY AB The Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model is used to simulate the atmospheric sulfur cycle. The model uses the assimilated meteorological data from the Goddard Earth Observing System Data Assimilation System (GEOS DAS). Global sulfur budgets from a 6-year simulation for SO2, sulfate, dimethylsulfide (DMS), and methanesulfonic acid (MSA) are presented in this paper. In a normal year without major volcanic perturbations, about 20% of the sulfate precursor emission is from natural sources (biogenic and volcanic), and 80% is anthropogenic; the same sources contribute 33% and 67%, respectively, to the total sulfate burden.,A sulfate production efficiency of 0.41-0.42 is estimated in the model, an efficiency which is defined as a ratio of the amount of sulfate produced to the total amount of SO2 emitted and produced in the atmosphere. This value indicates that less than half of the SO2 entering the atmosphere contributes to the sulfate production, the rest being removed by dry and wet depositions. In a simulation for 1990 we estimate a total sulfate production of 39 Tg S yr(-1), with 36% and 64% from in-air and in-cloud oxidation, respectively, of SO2. We also demonstrate that major volcanic eruptions, such as the Mount Pinatubo eruption in 1991, can significantly change the sulfate formation pathways, distributions, abundance, and lifetime. Comparison with other models shows that the parameterizations for wet removal or wet production of sulfate are the most critical factors in determining the burdens of SO2 and sulfate. Therefore a priority for future research should be to reduce the large uncertainties associated with the wet physical and chemical processes. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. Belgian Inst Space Aeron, Brussels, Belgium. RP Chin, M (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. EM chin@rondo.gsfc.nasa.gov; rood@dao.gsfc.nasa.gov; slin@dao.gsfc.nasa.gov; Jean-Francois.Muller@bira-iasb.oma.be; thompson@gator1.gsfc.nasa.gov RI Chin, Mian/J-8354-2012; Rood, Richard/C-5611-2008; Thompson, Anne /C-3649-2014 OI Rood, Richard/0000-0002-2310-4262; Thompson, Anne /0000-0002-7829-0920 NR 54 TC 251 Z9 255 U1 8 U2 52 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 2000 VL 105 IS D20 BP 24671 EP 24687 DI 10.1029/2000JD900384 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 367NQ UT WOS:000090068700005 ER PT J AU Chin, M Savoie, DL Huebert, BJ Bandy, AR Thornton, DC Bates, TS Quinn, PK Saltzman, ES De Bruyn, WJ AF Chin, M Savoie, DL Huebert, BJ Bandy, AR Thornton, DC Bates, TS Quinn, PK Saltzman, ES De Bruyn, WJ TI Atmospheric sulfur cycle simulated in the global model GOCART: Comparison with field observations and regional budgets SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CHARACTERIZATION EXPERIMENT ACE-1; MARINE BOUNDARY-LAYER; SEA-SALT SULFATE; DIMETHYL-SULFIDE; PACIFIC-OCEAN; TRANSPORT; DIOXIDE; SO2; CHEMISTRY; EMISSIONS AB We present a detailed evaluation of the atmospheric sulfur cycle simulated in the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model. The model simulations of SO2, sulfate? dimethylsulfide (DMS), and methanesulfonic acid (MSA) are compared with observations from different regions on various timescales. The model agrees within 30% with the regionally averaged sulfate concentrations measured over North America and Europe but overestimates the SO2 concentrations by more than a factor of 2 there. This suggests that either the emission rates are too high, or an additional loss of SO2 which does not lead to a significant sulfate production is needed. The average wintertime sulfate concentrations over Europe in the model are nearly a factor of 2 lower than measured values, a discrepancy which may be attributed largely to the sea-salt sulfate collected in the data. The model reproduces the sulfur distributions observed over the oceans in both long-term surface measurements and short-term aircraft campaigns. Regional budget analyses show that sulfate production from SO2 oxidation is 2 to 3 times more efficient and the lifetimes of SO2 and sulfate are nearly a factor of 2 longer over the ocean than over the land. This is due to a larger free tropospheric fraction of SO2 column over the ocean than over the land, hence less loss to the surface. The North Atlantic and northwestern Pacific regions are heavily influenced by anthropogenic activities? with more than 60% of the total SO2 originating from anthropogenic sources. The average production efficiency of SO2 from DMS oxidation is estimated at 0.87 to 0.91. in most oceanic regions. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Miami, FL 33149 USA. Univ Hawaii, Dept Oceanog, Honolulu, HI 96822 USA. Drexel Univ, Dept Chem, Philadelphia, PA 19104 USA. NOAA, Pacific Marine Environm Lab, Seattle, WA 98115 USA. RP Chin, M (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. EM chin@rondo.gsfc.nasa.gov; dsavoie@rsmas.miami.edu; huebert@soest.hawaii.edu; bandyar@drexel.edu; dct@drexel.edu; bates@pmel.noaa.gov; quinn@pmel.noaa.gov; esaltzma@nsf.gov; debruyn@rsmas.miami.edu RI Chin, Mian/J-8354-2012; Bates, Timothy/L-6080-2016; Quinn, Patricia/R-1493-2016 OI Quinn, Patricia/0000-0003-0337-4895 NR 50 TC 82 Z9 83 U1 2 U2 13 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 2000 VL 105 IS D20 BP 24689 EP 24712 DI 10.1029/2000JD900385 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 367NQ UT WOS:000090068700006 ER PT J AU Yu, SC Saxena, VK Wenny, BN DeLuisi, JJ Yue, GK Petropavlovskikh, IV AF Yu, SC Saxena, VK Wenny, BN DeLuisi, JJ Yue, GK Petropavlovskikh, IV TI A study of the aerosol radiative properties needed to compute direct aerosol forcing in the southeastern United States SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OPTICAL DEPTH; ANTHROPOGENIC AEROSOLS; SIZE DISTRIBUTION; NORTH-CAROLINA; CLIMATE; US; UNCERTAINTY; SHORTWAVE; IMPACT; INDEX AB To assess the direct radiative forcing due to aerosols in southeastern United States where a mild cooling is under way, an accurate set of data describing the aerosol radiative properties are needed. We report here aerosol optical depth (AOD) and diffuse-to-direct solar irradiance ratio (DDR) at three operational wavelengths (415, 500, 673 nm) determined by using Multifilter Rotating Shadowband Radiometers (MFRSR) at two sites (a mountain top site: Mount Gibbes, 35,78 degreesN, 82.29 degreesW, 2006 m mean sea level (msl); a valley site: Black Mountain, 35,66 degreesN, 82.38 degreesW, 951 m msl), which are separated horizontally by 10 km and vertically by 1 km. The characteristics AOD and DDR were determined from the field measurements obtained during 1995, It was found that the representative total AOD values at 500 nm at the valley site for highly polluted (HP), marine (M) and continental (C) air masses were 0.68 +/- 0.33, 0.29 +/- 0.19, and 0.10 +/- 0,04, respectively. The fact that the ratio of the mean 1 km layer optical depth to total mean optical depth at 500 nm from the valley site was 71% indicates that the major portion of the atmospheric aerosol was located in the lowest 1 km surface boundary layer (SBL). There was a significant linear correlation between the DDR and the total AOD at both sites. A simple, fast, and operative search-graph method was used to retrieve the columnar size distribution (number concentration N, effective radius r(eff), and geometric standard deviation a) from the optical depth observations at the three operational wavelengths. The ground albedo, single-scattering albedo, and imaginary part of the refractive index are calculated using a mathematically unique procedure involving a Mie code and a radiative transfer code in conjunction with the retrieved aerosol size distribution, AOD, and DDR, It was found that N, r(eff) and sigma (g) were in the range of 1.9 x 10 to 1.7 x 10(4) cm(-3), 0.09-0.68 mum, and 1.12-2.70, respectively. The asymmetry factor and single-scattering albedo were in the ranges of 0.63-0.75 and 0.74-0.99 respectively. The ground albedo over the forested terrain and the imaginary part of refractive index were found to be in the range of 0.08-0.29 and 0,005-0.051, respectively. C1 NOAA, Surface Radiat Res Branch, Boulder, CO 80303 USA. Univ Colorado, CIRES, Boulder, CO 80302 USA. N Carolina State Univ, Dept Marine Earth & Atmospher Sci, Raleigh, NC 27695 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Yu, SC (reprint author), Duke Univ, Nicholas Sch Environm, Durham, NC 27708 USA. EM saxena@eos.ncsu.edu RI yu, shaocai/G-7806-2011; yu, shaocai/F-1394-2014 NR 37 TC 24 Z9 24 U1 1 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 27 PY 2000 VL 105 IS D20 BP 24739 EP 24749 DI 10.1029/2000JD900346 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 367NQ UT WOS:000090068700010 ER PT J AU Koster, RD Suarez, MJ Ducharne, A Stieglitz, M Kumar, P AF Koster, RD Suarez, MJ Ducharne, A Stieglitz, M Kumar, P TI A catchment-based approach to modeling land surface processes in a general circulation model 1. Model structure SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PARAMETERIZATION SCHEMES; ATMOSPHERIC MODELS; BIOSPHERE MODEL; CLIMATE; HYDROLOGY; RUNOFF; SCALE; GCM; PRECIPITATION; SIMULATIONS AB A new strategy for modeling the land surface component of the climate system is described. The strategy is motivated by an arguable deficiency in most state-of-the-art land surface models, namely, the disproportionately higher emphasis given to the formulation of one-dimensional, vertical physics relative to the treatment of horizontal heterogeneity in surface properties, particularly subgrid soil moisture variability and its effects on runoff generation. The new strategy calls for the partitioning of the continental surface into a mosaic of hydrologic catchments, delineated through analysis of high-resolution surface elevation data. The effective "grid" used for the land surface is therefore not specified by the overlying atmospheric grid. Within each catchment, the variability of soil moisture is related to characteristics of the topography and to three bulk soil moisture variables through a well-established model of catchment processes. This modeled variability allows the partitioning of the catchment into several areas representing distinct hydrological regimes, wherein distinct (regime specific) evaporation and runoff parameterizations are applied. Care is taken to ensure that the deficiencies of the catchment model in regions of little to moderate topography are minimized. C1 NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Paris 06, Lab Sisyphe, F-75252 Paris 05, France. Columbia Univ, Lamont Doherty Earth Observ, New York, NY 10027 USA. Univ Illinois, Dept Civil Engn, Urbana, IL 61801 USA. RP Koster, RD (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Code 974, Greenbelt, MD 20771 USA. EM randal.koster@gsfc.nasa.gov RI Kumar, Praveen/D-2036-2010; Koster, Randal/F-5881-2012 OI Kumar, Praveen/0000-0002-4787-0308; Koster, Randal/0000-0001-6418-6383 NR 47 TC 288 Z9 295 U1 3 U2 34 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 2000 VL 105 IS D20 BP 24809 EP 24822 DI 10.1029/2000JD900327 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 367NQ UT WOS:000090068700016 ER PT J AU Ducharne, A Koster, RD Suarez, MJ Stieglitz, M Kumar, P AF Ducharne, A Koster, RD Suarez, MJ Stieglitz, M Kumar, P TI A catchment-based approach to modeling land surface processes in a general circulation model 2. Parameter estimation and model demonstration SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RIVER BASIN EXPERIMENT; SCHEMES PILPS; TEMPORAL ANALYSIS; PROJECT; PHASE; HYDROLOGY; CLIMATE; WATER; PARAMETRIZATION; TRANSPIRATION AB The viability of a new catchment-based land surface model (LSM) developed for use with general circulation models is demonstrated. First, simple empirical functions, tractable enough for operational use in the LSM, are established that faithfully capture the control of topography on the subgrid variability of soil moisture and the surface water budget, as predicted by theory. Next, the full LSM is evaluated off-line. Using forcing and validation data sets developed for the Project for Intercomparison of Land-Surface Parameterization Schemes Phase 2c, the minimally calibrated model is shown to reproduce observed evaporation and runoff fluxes successfully in the Red-Arkansas River Basin. A complementary idealized study that employs the range of topographic variability seen over North America demonstrates that the simulated surface water budget does vary strongly with topography, which can, by itself, induce variations in annual runoff as high as 20%. C1 Univ Paris 06, Lab Sisyphe, F-75252 Paris 05, France. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Atmospheres Lab, Greenbelt, MD 20771 USA. Columbia Univ, Lamont Doherty Earth Observ, New York, NY 10027 USA. Univ Illinois, Dept Civil Engn, Urbana, IL 61801 USA. RP Ducharne, A (reprint author), Univ Paris 06, Lab Sisyphe, Boite 123, F-75252 Paris 05, France. EM randal.koster@gsfc.nasa.gov RI Kumar, Praveen/D-2036-2010; Koster, Randal/F-5881-2012 OI Kumar, Praveen/0000-0002-4787-0308; Koster, Randal/0000-0001-6418-6383 NR 35 TC 105 Z9 105 U1 0 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 OCT 27 PY 2000 VL 105 IS D20 BP 24823 EP 24838 DI 10.1029/2000JD900328 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 367NQ UT WOS:000090068700017 ER PT J AU Lawrence, JK Cadavid, AC Ruzmaikin, A AF Lawrence, JK Cadavid, AC Ruzmaikin, A TI The response of atmospheric circulation to weak solar forcing SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NORTHERN-HEMISPHERE WINTER; MULTIPLE FLOW REGIMES; CLIMATE-CHANGE; IRRADIANCE; SYSTEMS; MODEL; TRANSITIONS; RADIATION; CYCLE; EARTH AB We study the effect of variable external forcing on a dynamical system proposed by Lorenz as "perhaps the simplest possible 'general circulation' model" of the atmosphere. When a strong annual cycle is included, numerical exploration reveals the existence of a variety of multiyear climate states, which fall into two basic types. In the space of external forcing parameters, the different kinds of climate state are interleaved in an intricate pattern at scales less than or equal to0.01%. Since this is below the similar to0.1% level of observed solar cycle irradiance variability, then the model climate state can be modulated by the solar variability. If the solar cycle is accompanied by a steady drift in forcing, it can produce periodic modulation that appears, disappears, and even reverses its phase. A parametric drift by itself produces intervals of steady, but sometimes differing, climates punctuated by intermittent bursts of variability. Different forcing parameters for the Northern and Southern Hemispheres produce different responses to variable forcing. We test the stability of the results under the addition of noise and changes of system parameters. C1 Calif State Univ Northridge, Dept Phys & Astron, Northridge, CA 91330 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Calif State Univ Northridge, Dept Phys & Astron, 18111 Nordhoff St, Northridge, CA 91330 USA. EM jlawrenc@galileo.csun.edu; aca-david@galileo.csun.edu; aruzmaik@mail1.jpl.nasa.gov NR 47 TC 4 Z9 4 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 OCT 27 PY 2000 VL 105 IS D20 BP 24839 EP 24848 DI 10.1029/2000JD900354 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 367NQ UT WOS:000090068700018 ER PT J AU Saunders, RS Zurek, RW AF Saunders, RS Zurek, RW TI Ideas about the surface runoff features on Mars SO SCIENCE LA English DT Letter ID ICE C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Saunders, RS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 2 Z9 2 U1 0 U2 1 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 OCT 27 PY 2000 VL 290 IS 5492 BP 712 EP 713 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 367ND UT WOS:000090067600020 ER PT J AU Westall, F Steele, A Toporski, J Walsh, M Allen, C Guidry, S McKay, D Gibson, E Chafetz, H AF Westall, F Steele, A Toporski, J Walsh, M Allen, C Guidry, S McKay, D Gibson, E Chafetz, H TI Polymeric substances and biofilms as biomarkers in terrestrial materials: Implications for extraterrestrial samples SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Review ID BARBERTON MOUNTAIN LAND; SOUTH-AFRICA; EXPERIMENTAL SILICIFICATION; MICROBIAL BIOFILMS; ONVERWACHT GROUP; MASS-TRANSPORT; LIFE; MICROFOSSILS; MICROORGANISMS; MARS AB Organic polymeric substances are a fundamental component of microbial biofilms. Microorganisms, especially bacteria, secrete extracellular polymeric substances (EPS) to form slime layers in which they reproduce. In the sedimentary environment, biofilms commonly contain the products of degraded bacteria as well as allochthonous and autochthonous mineral components. They are complex structures which serve as protection for the colonies of microorganisms living in them and also act as nutrient traps. Biofilms are almost ubiquitous wherever there is an interface and moisture (liquid/liquid, liquid/solid, liquid/gas, solid/gas). In sedimentary rocks they are commonly recognized as stromatolites. We also discuss the distinction between bacterial biofilms and prebiotic films. The EPS and cell components of the microbial biofilms contain many cation chelation sites which are implicated in the mineralization of the films. EPS, biofilms, and their related components thus have strong preservation potential in the rock record. Fossilized microbial polymeric substances (FPS) and biofilms appear to retain the same morphological characteristics as the unfossilized material and have been recognized in rock formations dating back to the Early Archaean (3.5 b.y.). We describe FPS and biofilms from hot spring, deep-sea, volcanic lake, and shallow marine/littoral environments ranging up to 3.5 b.y. in age. FPS and biofilms are more commonly observed than fossil bacteria themselves, especially in the older part of the terrestrial record. The widespread distribution of microbial biofilms and their great survival potential makes their fossilized remains a useful biomarker as a proxy for life with obvious application to the search for life in extraterrestrial materials. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Portsmouth, Sch Earth & Environm Sci, Astrobiol Grp, Portsmouth, Hants, England. Louisiana State Univ, Inst Environm Sci, Baton Rouge, LA 70803 USA. Univ Houston, Dept Geosci, Houston, TX 77204 USA. RP Westall, F (reprint author), Lunar & Planetary Inst, 300 Bay Area Blvd, Houston, TX 77058 USA. NR 108 TC 67 Z9 69 U1 2 U2 8 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 2000 VL 105 IS E10 BP 24511 EP 24527 DI 10.1029/2000JE001250 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 367WZ UT WOS:000090085700001 ER PT J AU Schenk, PM Moore, JM AF Schenk, PM Moore, JM TI Stereo topography of the south polar region of Mars: Volatile inventory and Mars Polar Lander landing site SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ORBITER-LASER-ALTIMETER; LAYERED DEPOSITS; HISTORY; OCEANS; WATER; CAP AB Viking stereo images and topographic maps reveal that the south polar layered deposits of Mars are topographically complex and morphologically distinct from the north polar layered deposits. The dominant feature is a 500-km-wide topographic dome that rises 3 km above the surrounding plains. This dome underlies the residual ice cap but is at least 50% larger in area. Erosional scarps and terraces indicate that this dome was once more extensive and has undergone erosional retreat. Adjacent to the dome, layered deposits form a vast plateau 1-1.5 km high extending similar to 1000 km beyond and to one side of the residual south polar cap. This plateau is relatively flat at kilometer scales, although it is cut in places by troughs and depressions, which have locally steep scarps up to 2 km high and sloping up to roughly 10 degrees. Contiguously flat kilometer-scale regions the size of the Mars Polar Lander (MPL) landing ellipse are present. These are in the form of plateaus 100-300 km wide and 1-2 km high. One of the largest of these plateaus tias been proposed as a landing site for the Mars Polar Lander (MPL). The volume associated with the south polar layered deposits may be comparable to those of the layered deposits at the north pole. Although this doubles the current probable inventory of surface ice on Mars, it still fails far short of accounting for the inferred volume of water on Mars in the past. C1 Lunar & Planetary Inst, Houston, TX 77058 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Schenk, PM (reprint author), Lunar & Planetary Inst, 300 Bay Area Blvd, Houston, TX 77058 USA. NR 31 TC 12 Z9 12 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 2000 VL 105 IS E10 BP 24529 EP 24546 DI 10.1029/1999JE001054 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 367WZ UT WOS:000090085700002 ER PT J AU Sullivan, R Greeley, R Kraft, M Wilson, G Golombek, M Herkenhoff, K Murphy, J Smith, P AF Sullivan, R Greeley, R Kraft, M Wilson, G Golombek, M Herkenhoff, K Murphy, J Smith, P TI Results of the imager for Mars Pathfinder windsock experiment SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ATMOSPHERIC SURFACE-LAYER; LANDING SITE; BOUNDARY-LAYER; INTERANNUAL VARIABILITY; ROUGHNESS ELEMENTS; SHEAR-STRESS; DUST STORMS; SAND DUNES; CAMERA; THRESHOLD AB The Imager for Mars Pathfinder (IMP) windsock experiment measured wind speeds at three heights within 1.2 m of the Martian surface during Pathfinder landed operations. These wind data allowed direct measurement of near-surface wind profiles on Mars for the first time, including determination of aerodynamic roughness length and wind friction speeds. Winds were light during periods of windsock imaging, but data from the strongest breezes indicate aerodynamic roughness length of 3 cm at the landing site, with wind friction speeds reaching 1 m/s. Maximum wind friction speeds were about half of the threshold-of-motion friction speeds predicted for loose, fine-grained materials on smooth Martian terrain and about one third of the threshold-of-motion friction speeds predicted for the same size particles over terrain with aerodynamic roughness of 3 cm. Consistent with this, and suggesting that low wind speeds prevailed when the windsock array was not imaged and/or no particles were available for aeolian transport, no wind-related changes to the surface during mission operations have been recognized. The aerodynamic roughness length reported here implies that proposed deflation of fine particles around the landing site, or activation of duneforms seen by IMP and Sojourner, would require wind speeds >28 m/s at the Pathfinder top windsock height (or >31 m/s at the equivalent Viking wind sensor height of 1.6 m) and wind speeds >45 m/s above 10 m. These wind speeds would cause rock abrasion if a supply of durable particles were available for saltation. Previous analyses indicate that the Pathfinder landing site probably is rockier and rougher than many other plains units on Mars, so aerodynamic roughness length elsewhere probably is less than the 3-cm value reported for the Pathfinder site. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RP Cornell Univ, Ctr Radiophys & Space Res, 308 Space Sci Bldg, Ithaca, NY 14853 USA. EM sullivan@cuspif.tn.cornell.edu NR 92 TC 43 Z9 43 U1 1 U2 9 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 2000 VL 105 IS E10 BP 24547 EP 24562 DI 10.1029/1999JE001234 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 367WZ UT WOS:000090085700003 ER PT J AU Matsuura, M Yamamura, I Murakami, H Onaka, T Ootsubo, T Tohya, T Okamura, Y Freund, MM Tanaka, M AF Matsuura, M Yamamura, I Murakami, H Onaka, T Ootsubo, T Tohya, T Okamura, Y Freund, MM Tanaka, M TI Infrared properties of SiO maser sources in late-type stars SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE infrared : stars; radio lines : stars; stars : atmospheres; stars : late-type; stars : long period variables ID EVOLVED STARS; CIRCUMSTELLAR ENVELOPES; NUMERICAL-CALCULATIONS; FLIGHT PERFORMANCE; AGB STARS; EMISSION; MIRAS; SUPERGIANTS; VARIABLES; WATER AB The results of an SiO maser survey for late-type stars selected by the IRTS (Infrared Telescope in Space) are presented. We have detected SiO J = 1-0, v = 1 and/or v = 2 lines in 27 stars out of 59 stars. The maser intensity increases with the depth of the H2O absorption in the infrared spectra and redness of the 2.2 and 12 mum color. The column densities of the water vapor in the target stars were estimated from the depth of the water absorption in the IRTS spectra. We found that the SiO maser was detected mostly in the stars with a column density of water vapor higher than 3 x 10(19)-3 x 10(20) cm(-2). We further estimated the density of hydrogen molecules in the outer atmosphere corresponding to these column densities, obtaining 10(9)-10(10) cm(-3) as a lower limit. These values are roughly in agreement with the critical hydrogen density predicted by models for the excitation of SiO masers. It is possible that the SiO masers are excited in clumps with column density even higher than this value. The present results provide useful information for the understanding of the physical conditions of the outer atmospheres in late-type stars. C1 Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. Univ Tokyo, Dept Astron, Bunkyo Ku, Tokyo 1130033, Japan. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Univ Tokyo, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan. NASA, Goddard Space Flight Ctr, Infrared Astrophys Branch, Greenbelt, MD 20771 USA. RP Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Kanagawa 2298510, Japan. EM mikako@ir.isas.ac.jp NR 49 TC 3 Z9 3 U1 0 U2 0 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0004-6264 EI 2053-051X J9 PUBL ASTRON SOC JPN JI Publ. Astron. Soc. Jpn. PD OCT 25 PY 2000 VL 52 IS 5 BP 895 EP 907 DI 10.1093/pasj/52.5.895 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 370JN UT WOS:000165119900020 ER PT J AU Keys, AS Fork, RL AF Keys, AS Fork, RL TI Full cycle, low loss, low distortion phase modulation from multilayered dielectric stacks with terahertz optical bandwidth SO OPTICS EXPRESS LA English DT Article ID QUANTUM-WELL; BAND-EDGE; DESIGN; GAAS AB We present a customized multilayered dielectric stack employed as a broadband phase modulator with 6.3 THz optical bandwidth. The bandpass modulator provides up to a full-cycle of near-uniform phase modulation across a defined signal spectrum with maximized transmission and minimized pulse phase distortion. The modulator offers a compact, lightweight approach to active wavefront phase control for large optical apertures without the use of mechanical actuators. The modulator also provides for rapid signal switching. We contrast the narrowband transmission of a standard Distributed Bragg Reflector (DBR) with the broadband transmission of our optimized bandpass modulator. We explore techniques for implementing rapid phase modulation while maintaining high average signal transmission levels. (C) 2000 Optical Society of America. C1 NASA, George C Marshall Space Flight Ctr, Space Opt Mfg Technol Ctr, Huntsville, AL 35812 USA. Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA. RP Keys, AS (reprint author), NASA, George C Marshall Space Flight Ctr, Space Opt Mfg Technol Ctr, SD72, Huntsville, AL 35812 USA. NR 20 TC 1 Z9 1 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1094-4087 J9 OPT EXPRESS JI Opt. Express PD OCT 23 PY 2000 VL 7 IS 9 BP 311 EP 322 PG 12 WC Optics SC Optics GA 366PR UT WOS:000090014200004 PM 19407881 ER PT J AU Schwenke, DW Partridge, H AF Schwenke, DW Partridge, H TI Convergence testing of the analytic representation of an ab initio dipole moment function for water: Improved fitting yields improved intensities SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID BAND INTENSITIES; POTENTIAL-ENERGY; SURFACES; H2O AB In general, when computing intensities for polyatomics, one has to interpolate the dipole moment function obtained from ab initio calculations. For some high overtones of the water molecule, the computed intensities can be very sensitive to the way in which the interpolation is done. Our previous analytic representation [H. Partridge and D. W. Schwenke, J. Chem. Phys. 106, 4618 (1997)] was not adequate. We show that stable results can be obtained, and these results are in much improved agreement with experiment. We also test the importance of core electron correlation on intensities, and find the effect to be negligible. Of the existing water dipole moment functions in the literature, the present one is the most accurate. (C) 2000 American Institute of Physics. [S0021-9606(00)30440-8]. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Schwenke, DW (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI schwenke, david/I-3564-2013 NR 12 TC 149 Z9 159 U1 0 U2 18 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD OCT 22 PY 2000 VL 113 IS 16 BP 6592 EP 6597 DI 10.1063/1.1311392 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 368RL UT WOS:000090131300014 ER PT J AU Barreiro, RB Hobson, MP Lasenby, AN Banday, AJ Gorski, KM Hinshaw, G AF Barreiro, RB Hobson, MP Lasenby, AN Banday, AJ Gorski, KM Hinshaw, G TI Testing the Gaussianity of the COBE DMR data with spherical wavelets SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE methods : data analysis; cosmic microwave background AB We investigate the Gaussianity of the 4-yr COBE DMR data (in HEAEPix pixelization) using an analysis based on spherical Haar wavelets. We use all the pixels lying outside the Galactic cut and compute the skewness, kurtosis and scale-scale correlation spectra for the wavelet coefficients at each scale. We also lake into account the sensitivity of the method to the orientation of the input signal. We find a detection of non-Gaussianity at >99 per cent level in just one of our statistics. Taking into account the total number of statistics computed, we estimate that the probability of obtaining such a detection by chance for an underlying Gaussian field is 0.69. Therefore, we conclude that the spherical wavelet technique shows no strong evidence of non-Gaussianity in the COBE DMR data. C1 Univ Cambridge, Cavendish Lab, Astrophys Grp, Cambridge CB3 0HE, England. Max Planck Inst Astrophys, D-85740 Garching, Germany. European So Observ, D-85740 Garching, Germany. Warsaw Univ Observ, PL-00478 Warsaw, Poland. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Barreiro, RB (reprint author), Univ Cambridge, Cavendish Lab, Astrophys Grp, Madingley Rd, Cambridge CB3 0HE, England. RI Barreiro, Rita Belen/N-5442-2014 OI Barreiro, Rita Belen/0000-0002-6139-4272 NR 19 TC 56 Z9 56 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 2000 VL 318 IS 2 BP 475 EP 481 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 374BT UT WOS:000165325100019 ER PT J AU Yue, GK AF Yue, GK TI Retrieval of stratospheric aerosol size distributions and integral properties from simulated lidar backscatter measurements SO APPLIED OPTICS LA English DT Article ID SAGE-II; EXTINCTION SPECTRA; PINATUBO; ERUPTION; INVERSION AB A new approach for retrieving aerosol properties from extinction spectra is extended to retrieve aerosol properties from lidar backscatter measurements. In this method it is assumed that aerosol properties are expressed as a linear combination of backscatters at three or fewer wavelengths commonly used in lidar measurements. The coefficients in the weighted linear combination are obtained by minimization of the retrieval error averaged for a set of testing size distributions. The formulas can be used easily by investigators to retrieve aerosol properties from lidar backscatter measurements such as the Lidar In-Space Technology Experiment and Pathfinder Instruments for Clouds and Aerosols Spaceborne Observations. OCIS codes: 010.1110, 010.1290, 010.1310, 010.3640. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Yue, GK (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, MS 475, Hampton, VA 23681 USA. EM g.k.yue@larc.nasa.gov NR 23 TC 3 Z9 3 U1 0 U2 1 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 2000 VL 39 IS 30 BP 5446 EP 5455 DI 10.1364/AO.39.005446 PG 10 WC Optics SC Optics GA 364ZV UT WOS:000089924700005 PM 18354540 ER PT J AU Chartas, G Worrall, DM Birkinshaw, M Cresitello-Dittmar, M Cui, W Ghosh, KK Harris, DE Hooper, EJ Jauncey, DL Kim, DW Lovell, J Mathur, S Schwartz, DA Tingay, SJ Virani, SN Wilkes, BJ AF Chartas, G Worrall, DM Birkinshaw, M Cresitello-Dittmar, M Cui, W Ghosh, KK Harris, DE Hooper, EJ Jauncey, DL Kim, DW Lovell, J Mathur, S Schwartz, DA Tingay, SJ Virani, SN Wilkes, BJ TI The Chandra X-ray Observatory resolves the X-ray morphology and spectra of a jet in PKS 0637-752 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : jets; quasars : individual (PKS 0637-752); X-rays : galaxies ID RADIO; EMISSION; QUASARS AB The core-dominated radio-loud quasar PKS 0637-752 (z = 0.654) was the first celestial object observed with the Chandra X-Ray Observatory, offering the early surprise of the detection of a remarkable X-ray jet. Several observations with a variety of detector configurations contribute to a total exposure time with the Chandra ACIS of about 100 ks. A spatial analysis of all the available X-ray data, making use of Chandra's spatial resolving power of about 0".4, reveals a jet that extends about 10 " to the west of the nucleus. At least four X-ray knots are resolved along the jet, which contains about 5% of the overall X-ray luminosity of the source. Previous observations of PKS 0637-752 in the radio band had identified a kiloparsec-scale radio jet extending to the west of the quasar. The X-ray and radio jets are similar in shape, intensity distribution, and angular structure out to about 9", after which the X-ray brightness decreases more rapidly and the radio jet turns abruptly to the north. The X-ray luminosity of the total source is log L-X approximate to 45.8 ergs s(-1) (2-10 keV) and appears not to have changed since it was observed with ASCA in 1996 November. We present the results of fitting a variety of emission models to the observed spectral distribution, comment on the nonexistence of emission lines recently reported in the ASCA observations of PKS 0637 - 752, and briefly discuss plausible X-ray emission mechanisms. C1 Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA. Univ Bristol, Dept Phys, Bristol BS8 1TL, Avon, England. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Australia Telescope Natl Facil, Epping, NSW 2121, Australia. Ohio State Univ, Columbus, OH 43210 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chartas, G (reprint author), Penn State Univ, Dept Astron & Astrophys, 525 Davey Lab, University Pk, PA 16802 USA. RI Tingay, Steven/B-5271-2013; OI Cui, Wei/0000-0002-6324-5772; Wilkes, Belinda/0000-0003-1809-2364 NR 17 TC 122 Z9 122 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP 655 EP 666 DI 10.1086/317049 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YN UT WOS:000165095500012 ER PT J AU White, RE Keel, WC Conselice, CJ AF White, RE Keel, WC Conselice, CJ TI Seeing galaxies through thick and thin. I. Optical opacity measures in overlapping galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; galaxies : ISM; galaxies : photometry; galaxies : spiral ID SPIRAL GALAXIES; SCATTERING PROPERTIES; DUST; DISKS; PAIR; NGC-3314; QUASARS; SYSTEMS; NGC-450; UGC-807 AB We describe the use of partially overlapping galaxies to provide direct measurements of the effective absorption in galaxy disks, independent of assumptions about internal disk structure. The nonoverlapping parts of the galaxies and symmetry considerations are used to reconstruct, via differential photometry, how much background galaxy light is lost in passing through the foreground disks. Extensive catalog searches and follow-up imaging yield similar to 15-25 nearby galaxy pairs suitable for varying degrees of our analysis; 11 of the best such examples are presented here. From these pairs, we find that interarm extinction is modest, declining from A(B) similar to 1 mag at 0.3R(25)(B) to essentially zero by R(25)(B); the interarm dust has a scale length consistent with that of the disk starlight. In contrast, dust in spiral arms and resonance rings may be optically thick (A(B) > 2) at virtually any radius. Some disks have flatter extinction curves than the Galaxy, with A(B)/A(I) approximate to 1.6; this is probably the signature of clumpy dust distributions. Even though typical spirals are not optically thick throughout their disks, where they are optically thick is correlated with where they are most luminous: in spiral arms and inner disks. This correlation between absorption and emission regions may account for their apparent surface brightness being only mildly dependent on inclination, erroneously indicating that spirals are generally optically thick. Taken as an ensemble, the opacities of spiral galaxies may be just great enough to significantly affect QSO counts, though not enough to cause their high-redshift cutoff. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP White, RE (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. RI Conselice, Christopher/B-4348-2013; OI Conselice, Christopher/0000-0003-1949-7638 NR 68 TC 52 Z9 52 U1 0 U2 0 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 20 PY 2000 VL 542 IS 2 BP 761 EP 778 DI 10.1086/317011 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YN UT WOS:000165095500022 ER PT J AU Dickins, JE Irvine, WM Snell, RL Bergin, EA Schloerb, FP Pratap, P Miralles, MP AF Dickins, JE Irvine, WM Snell, RL Bergin, EA Schloerb, FP Pratap, P Miralles, MP TI A study of the physics and chemistry of L134N SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : individual (L134N); ISM : molecules ID DENSE INTERSTELLAR CLOUDS; INTER-STELLAR CLOUDS; COLLISIONAL EXCITATION; ROTATIONAL-EXCITATION; SULFUR-DIOXIDE; DARK CLOUDS; ASTROPHYSICAL INTEREST; MICROWAVE-SPECTRA; MOLECULAR CLOUDS; AMMONIA AB We have carried out a comprehensive and self-consistent study of the physical and chemical state of the core of the dark cloud L134N (L183), whose molecular abundances provide a standard against which chemical models may be compared. We used observations of the NH(3)(1, 1) and (2, 2) rotation-inversion transitions to estimate the kinetic temperature, which was found to be consistent with 10 K and not varying with position. Densities were determined from multitransition statistical equilibrium calculations for HC(3)N, N(2)H(+), and CS. The average density toward all lines of sight was 2 x 10(4) cm(-3). As found by previous studies, the emission from various molecular species peaks in different positions: SO and SO(2) peak west of the central position, which is the location of the strongest emission from (e.g.) N(2)H(+) and CH(3)OH, with a second peak occurring for NH(3) and HC(3)N to the north of the center. The most striking abundance variations occur in a north-south cut through the core center for HC(3)N, C(2)H, CS, SO, and SO(2). A north to south decrease in the abundance of HC(3)N and CS and a dramatic change in the CS/SO ratio, which has been shown to be a sensitive tracer of chemical evolutionary state, suggests that the north is at a younger evolutionary state than the south. Despite the "youth" of the N position, the CS/SO ratio suggests that it is still as "old" as or older than the most evolved region in TMC-1 (the northwest end of the ridge). C1 Univ Massachusetts, Five Coll Radio Astron Observ, Amherst, MA 01003 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. MIT, Haystack Observ, Westford, MA 01886 USA. RP Dickins, JE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-506, Pasadena, CA 91109 USA. EM James.Dickens@jpl.nasa.gov NR 67 TC 89 Z9 89 U1 0 U2 0 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 OCT 20 PY 2000 VL 542 IS 2 BP 870 EP 889 DI 10.1086/317040 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YN UT WOS:000165095500031 ER PT J AU Palumbo, ME Pendleton, YJ Strazzulla, G AF Palumbo, ME Pendleton, YJ Strazzulla, G TI Hydrogen isotopic substitution studies of the 2165 wavenumber (4.62 micron) "XCN" feature produced by ion bombardment SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; ISM : lines and bands; ISM : molecules; line : identification; methods : laboratory; molecular processes ID INFRARED-SPECTROSCOPY; BAND; CO; ABSORPTION; SPECTRUM; CLOUDS; CHEMISTRY; MOLECULES; MIXTURES; MANTLES AB The interstellar 4.62 mum absorption band, commonly seen toward embedded protostellar objects, has not yet been unambiguously identified; here we report new results which further elucidate the components of the band carrier, which is often referred to in the literature as the "XCN" band due to previous implications of carbon and nitrogen. If the atmosphere of the early Earth was not overly reducing, as some studies indicate, production of prebiotic molecules containing the cyanogen bond would have been difficult. In that case, CN-bearing molecules, necessary for the origin of life, may have come primarily from extraterrestrial sources, and the interstellar medium may be an important source of those molecules. Laboratory studies show that energetic processing of ice mixtures containing H, C, N, and O atoms readily reproduce a band similar in peak position and profile to that seen in the interstellar spectra. Earlier isotopic labeling experiments clearly identified carbon, nitrogen, and oxygen as active participants of the XCN species. In this paper, results of ion bombardment of CH(3)OH:N(2) and CD(3) OD:N(2) ices are presented. A shift in band position resulting from deuterium substitution demonstrates that hydrogen is also a component of the carrier in the laboratory-produced 4.62 mum band. Irradiation of ices through ion bombardment allows the testing of mixtures which include N(2), a possible source of the available nitrogen in dense cloud ices that cannot be probed through UV photolysis experiments. C1 Osserv Astrofis Catania, I-95125 Catania, Italy. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Palumbo, ME (reprint author), Osserv Astrofis Catania, Citta Univ, I-95125 Catania, Italy. NR 30 TC 38 Z9 38 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 20 PY 2000 VL 542 IS 2 BP 890 EP 893 DI 10.1086/317061 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YN UT WOS:000165095500032 ER PT J AU Bernstein, MP Sandford, SA Allamandola, LJ AF Bernstein, MP Sandford, SA Allamandola, LJ TI H, C, N, and O isotopic substitution studies of the 2165 wavenumber (4.62 micron) "XCN" feature produced by ultraviolet photolysis of mixed molecular ices SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM : lines and bands; ISM : lines and bands; ISM : molecules; methods : laboratory ID SPECTRUM; BAND; INTERSTELLAR; ABSORPTION; ANALOGS; H2O; OCN; AR AB To better understand the chemical species that gives rise to the 2165 cm(-1) (4.62 mum) "XCN" absorption feature seen toward embedded protostars such as W33A, we have performed laboratory studies using deuterium (H-2) isotopic labeling. We report the observation of a small but significant deuterium isotope shift for the "XCN" peak which demonstrates that the atomic motion(s) causing the "XCN" band in the laboratory samples must involve hydrogen. We also report the results of C-13, N-15, and O-18 labeling experiments that are consistent with previously reported values. C1 SETI Inst, Mt View, CA 94043 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Bernstein, MP (reprint author), SETI Inst, 2035 Landings Dr, Mt View, CA 94043 USA. NR 17 TC 33 Z9 33 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP 894 EP 897 DI 10.1086/317062 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YN UT WOS:000165095500033 ER PT J AU Feibelman, WA AF Feibelman, WA TI The IUE and Hubble Space Telescope GHRS spectrum of the "hybrid"/PG 1159-type central star of the planetary nebula NGC 7094 SO ASTROPHYSICAL JOURNAL LA English DT Article DE line : identification; planetary nebulae : individual (NGC 7094); stars : AGB and post AGB; ultraviolet : stars ID OLD PLANETARIES; TERM ANALYSIS; FE-VII AB Absorption features in the IUE spectrum of the "hybrid" PG 1159-type central star of NGC 7094 have been identified and measured. We report equivalent widths for photospheric Fe vI and Fe vII features, interstellar and circumstellar absorptions, and variability of O v lambda 1371 and C Iv lambda 1549 P Cygni profiles. The terminal wind velocity of -3680 +/- 300 km s(-1) was determined from the high-dispersion C IV P Cyg feature. Some features from IUE and Hubble Space Telescope GHRS data are compared. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Feibelman, WA (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 18 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP 957 EP 963 DI 10.1086/317036 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YN UT WOS:000165095500038 ER PT J AU Bloser, PF Grindlay, JE Kaaret, P Zhang, W Smale, AP Barret, D AF Bloser, PF Grindlay, JE Kaaret, P Zhang, W Smale, AP Barret, D TI RXTE studies of long-term X-ray spectral variations in 4U 1820-30 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; stars : individual (4U 1820-30); stars : neutron; X-rays : stars ID QUASI-PERIODIC OSCILLATIONS; CLUSTER NGC 6624; NEUTRON-STARS; TIMING EXPLORER; ACCRETION DISKS; BLACK-HOLES; BINARIES; DISCOVERY; EMISSION; COMPTONIZATION AB We present the results of detailed spectral studies of the ultracompact low mass X-ray binary (LMXB) 4U 1820-30 carried out with the Rossi X-ray Timing Explorer (RXTE) during 1996-1997. 4U 1820-30 is an "atoll" source X-ray burster (XRB) located in the globular cluster NGC 6624. It is known to have an 11 minute binary period and a similar to 176 day modulation in its 2-12 keV flux. Observations were made with the PCA and HEXTE instruments on RXTE at roughly one-month intervals to sample this longterm period and study flux-related spectral changes. We find that the 176 day period corresponds to normal atoll source motion in the color-color diagram, indicating that the long period is due to mass accretion rate changes. There are clear correlations between our fitted spectral parameters and both the broadband (2-50 keV) flux and the position in the color-color diagram, as described by the parameter S, introduced by Mendez et al. The hard X-ray tail becomes more prominent at low flux levels as the source moves into the island state. In addition, we find a strong correlation between the position in the color-color diagram and the frequencies of the kilohertz quasi-periodic oscillations (kHz QPOs) reported by Zhang et al. This lends further support to the notion that evidence for the last stable orbit in the accretion disk of 4U 1820-30 has been observed. For a model consisting of Comptonization of cool photons by hot electrons plus an additional blackbody component, we report an abrupt change in the spectral parameters at the same accretion rate at which the kHz QPOs disappear, suggesting a change in the accretion flow that affects both the spectrum and the timing properties. For a model consisting of a multicolor disk blackbody plus a cut-off power law, we find that the inner disk radius reaches a minimum at the same accretion rate at which the kHz QPO frequency saturates, as expected if the disk reaches the last stable orbit. Both models face theoretical and observational problems when interpreted physically for this system. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Ctr Etud Spatiale Rayonnements, CNRS UPS, F-31028 Toulouse 04, France. RP Bloser, PF (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. EM pbloser@cfa.harvard.edu; zhang@xancusl0.gsfc.nasa.gov; Didier.Barret@cesr.fr RI Zhang, William/D-3535-2012 NR 64 TC 48 Z9 48 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 OCT 20 PY 2000 VL 542 IS 2 BP 1000 EP 1015 DI 10.1086/317019 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YN UT WOS:000165095500043 ER PT J AU Harris, MJ Teegarden, BJ Cline, TL Gehrels, N Palmer, DM Ramaty, R Seifert, H AF Harris, MJ Teegarden, BJ Cline, TL Gehrels, N Palmer, DM Ramaty, R Seifert, H TI Transient Gamma-Ray Spectrometer observations of gamma-ray lines from novae. II. Constraining the Galactic nova rate from a survey of the southern sky during 1995-1997 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : observations; novae, cataclysmic variables; nuclear reactions, nucleosynthesis, abundances; white dwarfs ID POSITRON-ANNIHILATION; CLASSICAL NOVAE; SPATIAL-DISTRIBUTION; GALAXY; EMISSION; LIMITS AB The good energy resolution (3-4 keV FWHM) of the Transient Gamma-Ray Spectrometer (TGRS) on board the Wind spacecraft makes it sensitive to Doppler-shifted outbursts of 511 keV electron-positron annihilation radiation, the reason being that the Doppler shift causes the cosmic line to be slightly offset from a strong instrumental background 511 keV line at rest, which is ubiquitous in space environments. Such a cosmic line (blueshifted) is predicted to arise in classical novae because of the annihilation of positrons from beta -decay on a timescale of a few hours in an expanding envelope. A further advantage of TGRS-its broad field of view, containing the entire southern ecliptic hemisphere-has enabled us to make a virtually complete and unbiased three-year search for classical novae at distances up to similar or equal to1 kpc. We present negative results of this search and estimate its implications for the highly uncertain Galactic classical nova rate and for future space missions. C1 NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. RP Harris, MJ (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Code 930-5, Greenbelt, MD 20771 USA. EM harris@tgrs2.gsfc.nasa.gov NR 37 TC 13 Z9 13 U1 0 U2 0 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 20 PY 2000 VL 542 IS 2 BP 1057 EP 1063 DI 10.1086/317022 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YN UT WOS:000165095500047 ER PT J AU Cheng, FH Horne, K Marsh, TR Hubeny, I Sion, EM AF Cheng, FH Horne, K Marsh, TR Hubeny, I Sion, EM TI Temporal variations of the white dwarf and disk in OY carinae following the 1992 superoutburst SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : eclipsing; novae, cataclysmic variables; stars : individual (OY Carinae); white dwarfs ID VW HYDRI; ACCRETION BELT; QUIESCENCE; ATMOSPHERES; ULTRAVIOLET; OUTBURST; NOVAE; IUE AB Hubble Space Telescope observations of the eclipsing dwarf nova OY Carinae after its 1992 April superoutburst are used to isolate ultraviolet spectra (1150-2500 Angstrom at 9.2 Angstrom FWHM resolution) of the white dwarf, the accretion disk, and the bright spot. The white dwarf spectra have a Stark-broadened photospheric Ly alpha absorption feature but are veiled by a forest of absorption features that we attribute to absorption by intervening disk material (a curtain). All the spectral fits required supersonic turbulence in the curtain material with Mach numbers of 6-8. All curtain temperatures were between 10,000 and 11,000 K. There was a curtain temperature increase similar to 3 months after the superoutburst. We find that the white dwarf temperature changed from 19,700 K just 27 days after the end of the superoutburst to 18,000 K roughly 3 months after the superoutburst; the exponential (e-folding) decay time of the white dwarf temperature was 66 days. We present evidence that the heating of the white dwarf was more extensive during the superoutburst than the normal outburst. The thermal response of the OY Car white dwarf to outburst heating is compared with WZ Sagittae, VW Hydri (the most similar dwarf nova to OY Car), and the cooling timescales of other dwarf novae after superoutburst. The measured cooling timescales of the five systems with superoutbursts appear to be shorter the longer the orbital period (accretion rate). Possible implications are discussed. There is evidence of a disk flux variation, independent of the effect of white dwarf cooling, which suggests a possible contradiction of the disk instability model. To establish this, however, data are required throughout a quiescent cycle. C1 Univ Sci & Technol China, Ctr Astrophys, Hefei 230026, Anhui, Peoples R China. Villanova Univ, Villanova, PA 19085 USA. Univ St Andrews, Sch Phys & Astron, St Andrews KY16 9SS, Fife, Scotland. Univ Southampton, Dept Phys, Southampton SO17 1BJ, Hants, England. Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Cheng, FH (reprint author), Univ Sci & Technol China, Ctr Astrophys, Hefei 230026, Anhui, Peoples R China. NR 25 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP 1064 EP 1070 DI 10.1086/317012 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YN UT WOS:000165095500048 ER PT J AU Boyd, PT Smale, AP Homan, J Jonker, PG van der Klis, M Kuulkers, E AF Boyd, PT Smale, AP Homan, J Jonker, PG van der Klis, M Kuulkers, E TI Canonical timing and spectral behavior of LMC X-3 in the low/hard state SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; binaries : close; black hole physics; stars : individual (LMC X-3); X-rays : stars ID VARIABILITY; DISCOVERY; SYSTEMS AB We present results from three observations with the Rossi X-Ray Timing Explorer (RXTE) of LMC X-3, obtained while the source was in an extended low/hard state. The data reveal a hard X-ray spectrum that is well fit by a pure power law with photon index Gamma = 1.69 +/- 0.02, with a source luminosity at 50 kpc of (5-16) x 10(36) ergs s(-1) (2-10 keV). Strong broadband (0.01-100 Hz) time variability is also observed, with fractional rms amplitude 40% +/- 4%, plus a quasi-periodic oscillation (QPO) peak at 0.46 +/- 0.02 Hz with rms amplitude similar to 14%. This is the first reported observation in which the full canonical low/hard state behavior (pure hard power-law spectrum combined with strong broadband noise and QPO) for LMC X-3 is seen. We reanalyze several archival RXTE observations of LMC X-3, derive consistent spectral and timing parameters, and determine the overall luminosity variation between high/soft and low/hard states. The timing and spectral properties of LMC X-3 during the recurrent low/hard states are quantitatively similar to that typically seen in the Galactic black hole candidates. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Space Res Org Netherlands, NL-3584 CA Utrecht, Netherlands. Univ Space Res Assoc, Columbia, MD 21044 USA. Univ Maryland Baltimore Cty, Joint Astron Ctr, Baltimore, MD 21250 USA. Natl Inst Nucl & High Energy Phys, Ctr High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands. Univ Utrecht, Inst Astron, NL-3508 TA Utrecht, Netherlands. RP Boyd, PT (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. RI Boyd, Patricia/D-3274-2012 NR 22 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP L127 EP L130 DI 10.1086/312931 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YQ UT WOS:000165095700013 ER PT J AU Devine, D Grady, CA Kimble, RA Woodgate, B Bruhweiler, FC Boggess, A Linsky, JL Clampin, M AF Devine, D Grady, CA Kimble, RA Woodgate, B Bruhweiler, FC Boggess, A Linsky, JL Clampin, M TI A Ly alpha bright jet from a Herbig Ae star SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; planetary systems; stars : individual (HD 163296); stars : pre-main-sequence ID YOUNG STELLAR OBJECTS; AE/BE STARS; HARO OBJECTS; OUTFLOWS; EMISSION; SPECTRA; MODELS; WINDS AB We report the detection in Ly alpha of a collimated, bipolar outflow (HH 409) associated with the 1.5-10 Myr old Herbig Ae star HD 163296. A blueshifted jet is visible in Ly alpha and Si III extending toward the southwest for at least 6" (725 AU). The combination of low line-of-sight extinction and relative faintness of the central star near Ly alpha enables us to trace the jet to within an unprecedented 0".06 (7.3 AU) of HD 163296. The jet has a radial velocity of 335-380 km s(-1), which is common for protostellar outflows. We also detected redshifted Ly alpha emission southwest of the star that may be due to infall or a poorly collimated wind component. If the age of the star is correct, then protostellar outflows may last up to 10 times longer than previously believed. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Catholic Univ Amer, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Devine, D (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. RI Clampin, mark/D-2738-2012; Kimble, Randy/D-5317-2012 NR 23 TC 46 Z9 46 U1 0 U2 0 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 20 PY 2000 VL 542 IS 2 BP L115 EP L118 DI 10.1086/312939 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YQ UT WOS:000165095700010 ER PT J AU Gao, Y Xu, C AF Gao, Y Xu, C TI CO in Stephan's Quintet: First evidence of molecular gas in the intragroup starburst SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : individual (HCG 92); galaxies : individual (NGC 7318B, NGC 7319); galaxies : interactions; galaxies : starburst; infrared : galaxies; intergalactic medium; ISM : molecules ID HICKSON COMPACT-GROUPS; STAR-FORMATION; GALAXIES; COMPLEX AB We present the first interferometric evidence of CO (1-0) emission in the intragroup starburst (IGS) region of HCG 92 (Stephan's Quintet). BIMA's large primary beam fully covers both the IGS region and the dominant group member Seyfert galaxy NGC 7319, as well as partially covering the intruder galaxy NGC 7318B. CO emission of greater than or equal to4 sigma is detected in all of them. The detection of the CO emission associated with the IGS is further supported by comparisons with observations in other wave bands (e.g., H I, mid-IR, and H alpha). Assuming the standard conversion factor, (3.6-8.0) x 10(8) M. molecular gas is found to be associated with the IGS. By confining ourselves to the region of the CO emission peak, we find that a relatively high star formation efficiency of 8.6 L./M. is derived for the IGS, which is nearly comparable to that of local starburst galaxies. The IGS triggering mechanism is also briefly discussed. C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Univ Toronto, Dept Astron, Toronto, ON M5S 3H8, Canada. Univ Illinois, Dept Astron, Urbana, IL 61801 USA. RP Gao, Y (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, MS 100-22,770 S Wilson Ave, Pasadena, CA 91125 USA. NR 23 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP L83 EP L87 DI 10.1086/312940 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YQ UT WOS:000165095700004 ER PT J AU Gardner, JP Brown, TM Ferguson, HC AF Gardner, JP Brown, TM Ferguson, HC TI Ultraviolet galaxy counts from Space Telescope Imaging Spectrograph observations of the Hubble Deep Fields SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; diffuse radiation; galaxies : evolution; galaxies : statistics; surveys; ultraviolet : galaxies ID FAINT GALAXIES; DATA REDUCTION; 2000 ANGSTROM; EVOLUTION; LUMINOSITY; PHOTOMETRY; REDSHIFT AB We present galaxy counts in the near-ultraviolet (NUV; 2365 Angstrom) and far-ultraviolet (FUV; 1595 Angstrom) obtained from Space Telescope Imaging Spectrograph observations of portions of the Hubble Deep Field-North (HDF-N), the Hubble Deep Field-South (HDF-S), and a parallel field near the HDF-N. All three fields have deep (AB > 29) optical imaging, and we determine magnitudes by taking the ultraviolet flux detected within the limiting optical isophote. An analysis of the UV-optical colors of detected objects, combined with a visual inspection of the UV images, indicates that there are no detectable objects in the UV images that are not also detected in the optical. We determine our detection area and completeness as a function of magnitude with a simulated distribution of galaxies based on the HDF-N Wide Field Planetary Camera 2 (WFPC2) V + I image. The galaxy counts reach to NUVAB = 29 and FUVAB = 30, which is 1 mag fainter than the HDF-N WFPC2/F300W counts and 7 mag fainter than balloon-based counts. We integrate our measurements in order to present the extragalactic background radiation coming from resolved objects. The NUV galaxy counts show a flattening or turnover beginning at about NUVAB = 26.0, which is not predicted either by no-evolution models based on a local luminosity function with a steep faint-end slope or by a semianalytic model in which starbursts are caused by major mergers. The FUV counts also show a flat slope. We argue that the flat slopes could be caused by a short duty cycle for star formation, additional starbursts triggered by minor mergers, and an extended quiescent phase between starburst episodes. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Gardner, JP (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 30 TC 53 Z9 53 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP L79 EP L82 DI 10.1086/312930 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YQ UT WOS:000165095700003 ER PT J AU Sekanina, Z AF Sekanina, Z TI Secondary fragmentation of the Solar and Heliospheric Observatory sungrazing comets at very large heliocentric distance SO ASTROPHYSICAL JOURNAL LA English DT Article DE comets : general; methods : data analysis ID CORONAGRAPH AB The temporal distribution of the Kreutz group of sungrazing comets has been known to have an episodic character on timescales from weeks to tens of years. With the large number of minor members of this group being nowadays discovered in images taken with the Solar and Heliospheric Observatory coronagraphs, it has become apparent that the distribution of these faint comets is episodic on a much shorter timescale, with objects arriving in pairs during a small fraction of a day. It is shown that the rate of these pairs is much too high for a random sample. Their existence is readily explained as a result of secondary, low-velocity, nontidal fragmentation episodes, which occur virtually spontaneously at very large heliocentric distances and involve the products of near-perihelion splitting of progenitor fragments during their previous return to the Sun. In fact, the pairs are merely extreme manifestations of larger clusters of such subnuclei, with a complex hierarchy of fragments. Each cluster is an outcome of a sequence of nontidal fragmentation events, which begins-after the initial tidal breakup-at some point along the outbound leg of the orbit and then continues episodically to and past aphelion. A similar scenario of posttidal progressive disintegration was firmly established for comet Shoemaker-Levy 9, based on extensive observations of its secondary and tertiary nuclei during many months preceding the comet's collision with Jupiter. Also, there are similarities with the mechanism proposed recently for the formation of striations in the dust tail of comet Hale-Bopp, and a logical extension of this process is the evolution of comet dust trails. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sekanina, Z (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP L147 EP L150 DI 10.1086/312943 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YQ UT WOS:000165095700018 ER PT J AU Takahashi, T Kataoka, J Madejski, G Mattox, J Urry, CM Wagner, S Aharonian, F Catanese, M Chiappetti, L Coppi, P Degrange, B Fossati, G Kubo, H Krawczynski, H Makino, F Marshall, H Maraschi, L Piron, F Remillard, R Takahara, F Tashiro, M Terasranta, H Weekes, T AF Takahashi, T Kataoka, J Madejski, G Mattox, J Urry, CM Wagner, S Aharonian, F Catanese, M Chiappetti, L Coppi, P Degrange, B Fossati, G Kubo, H Krawczynski, H Makino, F Marshall, H Maraschi, L Piron, F Remillard, R Takahara, F Tashiro, M Terasranta, H Weekes, T TI Complex spectral variability from intensive multiwavelength monitoring of Markarian 421 in 1998 SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL Lacertae objects : general; BL Lacertae objects : individual (Markarian 421); X-rays : general ID ACTIVE GALACTIC NUCLEI; X-RAY; ENERGY-DISTRIBUTIONS; RAPID VARIABILITY; BLAZARS; EMISSION; ACCELERATION; FLARE AB We conducted a multifrequency campaign for the TeV blazar Markarian 421 in 1998 April. The campaign started from a pronounced high-amplitude flare recorded by BeppoSAX and Whipple; the ASCA observation started 3 days later. In the X-ray data, we detected multiple flares, occurring on timescales of about 1 day. ASCA data clearly reveal spectral variability. The comparison of the data from ASCA, the Extreme Ultraviolet Explorer, and the Rossi X-Ray Timing Explorer indicates that the variability amplitudes in the low-energy synchrotron component are larger at higher photon energies. In TeV gamma -rays, large intraday variations-which were correlated with the X-ray flux-were observed when results from three Cerenkov telescopes were combined. The rms variability of TeV gamma -rays was similar to that observed in hard X-rays, above 10 keV. The X-ray light curve reveals flares that are almost symmetric for most cases, implying that the dominant timescale is the light crossing time through the emitting region. The structure function analysis based on the continuous X-ray light curve of 7 days indicates that the characteristic timescale is similar to0.5 days. The analysis of ASCA light curves in various energy bands appears to show both soft (positive) and hard (negative) lags. These may not be real, as systematic effects could also produce these lags, which are all much smaller than an orbit. If the lags of both signs are red, these imply that the particle acceleration and X-ray cooling timescales are similar. C1 Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. Univ Tokyo, Dept Phys, Tokyo 1130033, Japan. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Boston Univ, Dept Astron, Boston, MA 02215 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Landessternwarte Heidelberg, D-69117 Heidelberg, Germany. Max Planck Inst Kernphys, D-69029 Heidelberg, Germany. Harvard Smithsonian Ctr Astrophys, Fred Lawrence Whipple Observ, Amado, AZ 85645 USA. CNR, Inst Fis Cosm, I-20133 Milan, Italy. Yale Univ, Dept Astron, New Haven, CT 06520 USA. Ecole Polytech, Lab Phys Nucl Haute Energies, Palaiseau, France. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. Tokyo Inst Technol, Dept Phys, Tokyo 1528551, Japan. MIT, Ctr Space Res, Cambridge, MA 02139 USA. Osservatorio Astron Brera, I-20121 Milan, Italy. Osaka Univ, Dept Earth & Space Sci, Osaka, Japan. Metsahove Radio Observ, Kylmala, Finland. RP Takahashi, T (reprint author), Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 2298510, Japan. RI Fossati, Giovanni/A-5841-2009; Tashiro, Makoto/J-4562-2012; Urry, Claudia/G-7381-2011 OI Urry, Claudia/0000-0002-0745-9792 NR 30 TC 77 Z9 77 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP L105 EP L109 DI 10.1086/312929 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YQ UT WOS:000165095700008 ER PT J AU Titarchuk, L Osherovich, V AF Titarchuk, L Osherovich, V TI The global normal disk oscillations and the persistent low-frequency quasi-periodic oscillations in X-ray binaries SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; diffusion; stars : individual (EXO 0748-676, GRO J1655-40, Hercules X-1, LMC X-1, XTE J1118+480, 4U 1323-62, 4U 1746-31); stars : neutron; X-rays : stars ID NEUTRON-STAR BINARIES; BLACK-HOLES; GRO J1655-40; MASS; SPECTRA; LMC-X-1; X-1 AB We suggest that persistent low-frequency quasi-periodic oscillations (QPOs) detected in the black hole (BH) sources XTE J1118+480, GRO J1655-40, and LMC X-l at similar to0.1 Hz, in HZ Her/Her X-l at similar to0.05 Hz, and in neutron star (NS) binaries 4U 1323-62, 4U 1746-31, and EXO 0748--76 at similar to1 Hz are caused by the global disk oscillations in the direction normal to the disk (normal mode). We argue that these disk oscillations are a result of the gravitational interaction between the central compact object and the disk. A small displacement of the disk from the equatorial plane results in a linear gravitational restoring force opposite to this displacement. Our analysis shows chat the frequency of this mode is a function of the mass of the central object and that it also depends on the inner and outer radii of the disk, which in turn are related to the orbital period of the binary system. We derive an analytical formula for the frequency of the normal disk mode and show that these frequencies can be related to the persistent lower QPO frequencies observed in the NS and BH sources. We offer a new independent approach to the BH mass determination by interpreting this low QPO frequency as the global disk oscillation frequency. The implementation of this method combined with the independent method recently developed by Shrader & Titarchuk that uses the X-ray energy spectra results in stringent constraints for the BH masses. C1 NASA, Goddard Space Flight Ctr, Raytheon Informat Technol & Sci Serv, Greenbelt, MD 20771 USA. George Mason Univ, Ctr Earth Observing & Space Res, Fairfax, VA 22030 USA. USN, Res Lab, Washington, DC 20375 USA. RP Titarchuk, L (reprint author), NASA, Goddard Space Flight Ctr, Raytheon Informat Technol & Sci Serv, Greenbelt, MD 20771 USA. NR 36 TC 36 Z9 37 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 20 PY 2000 VL 542 IS 2 BP L111 EP L114 DI 10.1086/312935 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YQ UT WOS:000165095700009 ER PT J AU Walch, SP Ramalingam, S Aydil, ES Maroudas, D AF Walch, SP Ramalingam, S Aydil, ES Maroudas, D TI Mechanism and energetics of dissociative adsorption of SiH3 on the hydrogen-terminated Si(001)-(2 x 1) surface SO CHEMICAL PHYSICS LETTERS LA English DT Article ID MOLECULAR-DYNAMICS SIMULATIONS; PLASMA-INDUCED DEPOSITION; AMORPHOUS-SILICON; ATOMISTIC SIMULATION; RADICAL DEPOSITION; FILM GROWTH; SILANE; ABSTRACTION; DISCHARGES AB A comprehensive theoretical study is presented of the adsorption mechanism and energetics of the silyl (SiH3) radical on the Si(001)-(2 x 1) surface terminated by one monolayer of hydrogen atoms. SiH3 adsorbs on the surface dissociatively through an insertion reaction that involves breaking of the Si-Si surface dimer bond and subsequent transfer of an H atom from the radical to an atom of the broken dimer, thus leading to formation of two surface dihydride (SiH2) species. The structure and energies of the corresponding equilibrium and transition-state configurations are presented, as well as detailed energetics along the reaction pathway. (C) 2000 Elsevier Science B.V. C1 Univ Calif Santa Barbara, Dept Chem Engn, Santa Barbara, CA 93106 USA. NASA, Ames Res Ctr, Thermosci Inst, Moffett Field, CA 94035 USA. RP Maroudas, D (reprint author), Univ Calif Santa Barbara, Dept Chem Engn, Santa Barbara, CA 93106 USA. NR 26 TC 30 Z9 30 U1 1 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 OCT 20 PY 2000 VL 329 IS 3-4 BP 304 EP 310 DI 10.1016/S0009-2614(00)01007-1 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 367WX UT WOS:000090085500018 ER PT J AU Garces, JE Bozzolo, GH Abel, P Mosca, HO AF Garces, JE Bozzolo, GH Abel, P Mosca, HO TI A new approach for atomistic modeling of Pd/Cu(110) surface alloy formation SO APPLIED SURFACE SCIENCE LA English DT Article DE surface alloys; atomistic simulations; BFS method; Pd/Cu alloys ID EQUIVALENT-CRYSTAL THEORY; DEFECT STRUCTURE; GROWTH; PD; CU(100); CU(100)-C(2X2)PD; CHEMISORPTION; RELAXATION; SYSTEMS; CU(001) AB The formation process of Pd/Cu(110) surface alloys is investigated using the Bozzolo-Ferrante-Smith (BFS) method for alloys. A straightforward modeling approach is introduced, ranging from the deposition of one single-Pd atom to the formation of Pd/Cu surface alloy, which helps explain all the experimentally observed features during the surface alloy formation for low coverages. In excellent agreement with all the known experimental observations, the approach sheds light on the exchange mechanism between adatoms and substrate atoms, the formation of Pd-Cu chains and the formation of Cu islands. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Comis Nacl Energia Atom, Ctr Atom Bariloche, RA-8400 Bariloche, Rio Negro, Argentina. Ohio Aerosp Inst, Cleveland, OH 44142 USA. Comis Nacl Energia Atom, RA-1429 Buenos Aires, DF, Argentina. Univ Buenos Aires, Fac Ciencias Exactas & Nat, Dept Fis, RA-1428 Buenos Aires, DF, Argentina. RP Bozzolo, GH (reprint author), NASA, Glenn Res Ctr, Mail Stop 23-2, Cleveland, OH 44135 USA. NR 27 TC 11 Z9 11 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-4332 J9 APPL SURF SCI JI Appl. Surf. Sci. PD OCT 16 PY 2000 VL 167 IS 1-2 BP 18 EP 33 DI 10.1016/S0169-4332(00)00380-9 PG 16 WC Chemistry, Physical; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Chemistry; Materials Science; Physics GA 355TL UT WOS:000089402400003 ER PT J AU Rinsland, CP Mahieu, E Zander, R Demoulin, P Forrer, J Buchmann, B AF Rinsland, CP Mahieu, E Zander, R Demoulin, P Forrer, J Buchmann, B TI Free tropospheric CO, C2H6, and HCN above central Europe: Recent measurements from the Jungfraujoch station including the detection of elevated columns during 1998 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID INFRARED SPECTROSCOPIC MEASUREMENTS; ATMOSPHERIC CARBON-MONOXIDE; IR SOLAR SPECTRA; ETHANE C2H6; VERTICAL-DISTRIBUTION; LOWER STRATOSPHERE; SEASONAL-VARIATION; HYDROGEN-CYANIDE; BOUNDARY-LAYER; TRACE GASES AB Time series of free tropospheric carbon monoxide (CO), ethane (C2H6), and hydrogen cyanide (HCN) column abundances have been derived from observations at the International Scientific Station of the Jungfraujoch (ISSJ) at 3.58-km altitude in the Swiss Alps (latitude 46.55 degreesN, 7.98 degreesE longitude). The free troposphere was assumed to extend from 3.58 to 11 km altitude, and the related columns were derived for all three molecules from high spectral resolution infrared solar spectra recorded between January 1995 and October 1999. The three molecules show distinct seasonal cycles with maxima during winter for CO and C2H6, and during spring for HCN. These seasonal changes are superimposed on interannual variations. The tropospheric columns of all three molecules were elevated during 1998. Increases were most pronounced for HCN with enhanced values throughout the year, up to a factor of 2 in January 1998 when compared to averages of the other years. The increased tropospheric columns coincide with the period of widespread wildfires during the strong El Nino warm phase of 1997-1998. The emission enhancements above ISSJ are less pronounced, and they peaked after the increases measured above Mauna Loa (19.55 degreesN, 155.6 degreesW). Tropospheric trends for CO, C2H6, and HCN of (2.40 +/- 0.49), (0.47 +/- 0.64), and (7.00 +/- 1.61)% yr(-1)(1 sigma) were derived for January 1995 to October 1999. However, if 1998 measurements are excluded from the fit, CO and HCN trends that are not statistically significant, and a statistically significant decrease in the C2H6 tropospheric column, are inferred. Comparisons of the infrared CO columns with CO in situ surface measurements suggest that the CO free tropospheric vertical Volume mixing ratio profile generally decreases with altitude throughout the year. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. Swiss Fed Labs Mat Testing & Res, Dubendorf, Switzerland. RP Rinsland, CP (reprint author), NASA, Langley Res Ctr, 401A, Hampton, VA 23681 USA. EM c.p.rinsland@larc.nasa.gov; Emmanuel.Mahieu@ulg.ac.be; zander@astro.ulg.ac.be; demoulin@astro.ulg.ac.be; jann.forrer@empa.ch; brigitte.buchmann@empa.ch NR 65 TC 61 Z9 61 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 2000 VL 105 IS D19 BP 24235 EP 24249 DI 10.1029/2000JD900371 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 366WM UT WOS:000090029300005 ER PT J AU Tsou, JJ Connor, BJ Parrish, A Pierce, RB Boyd, IS Bodeker, GE Chu, WP Russell, JM Swart, DPJ McGee, TJ AF Tsou, JJ Connor, BJ Parrish, A Pierce, RB Boyd, IS Bodeker, GE Chu, WP Russell, JM Swart, DPJ McGee, TJ TI NDSC millimeter wave ozone observations at Lauder, New Zealand, 1992-1998: Improved methodology, validation, and variation study SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC OZONE; LIDAR; TEMPERATURE; OZONESONDES AB A ground-based millimeter wave radiometer for the Network for the Detection of Stratospheric Change (NDSC) was installed at Lauder, New Zealand (45 degreesS, 169.7 degreesE) in November 1992. It has been monitoring the middle atmospheric ozone with nearly continuous operation since then. Owing to special complications in the observing conditions at this southern midlatitude site, three refinements to the data analysis and calibration techniques were proposed: (1) the use of a radiative model of local tropospheric climate adopted to the low surface elevation of the observing site, (2) the correction of observing angle measurements due to the settling of the foundation of the site, and (3) the improved method of radiometric temperature determination of calibration sources. All data from 1992 to 1998 were reprocessed with these modifications implemented. The retrieved ozone profiles are compared to sonde, two lidars, and satellite (Halogen Occultation Experiment (HALOE), Stratospheric Aerosol and Gas Experiment (SAGE II)) overpass measurements. The agreement is very good, with mean differences from 56 to 1 mbar of generally 2-3% for the comparisons with sonde, HALOE, and SAGE II, and generally <5% for the comparisons with lidars when large samples are considered. The root-mean-square scatter about the mean differences is mostly consistent with the expected (combined) precision. In comparisons with these correlative measurements, the millimeter wave ozone observations are found to have no seasonal bias, no comparison bias due to the a priori profiles used in millimeter wave data retrievals, and no observable instrument drift from 1992 to 1998, Better agreement is found in the comparison with sonde data if suspected vertical shifts in the sonde profiles are considered. The variations seen in the 6 year millimeter wave ozone data are shown to be mostly in line with photochemistry and dynamic transport processes in the mid austral latitudes. These processes, however, are apparently modulated somewhat by the Antarctic polar vortex circulation in winter seasons in the upper stratosphere. C1 NASA, LaRC, Hampton, VA 23618 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Applicat Int Corp, Hampton, VA USA. Univ Massachusetts, Dept Astron, Amherst, MA 01003 USA. Hampton Univ, Dept Phys, Hampton, VA 23668 USA. Natl Inst Publ Hlth & Environm, NL-3720 BA Bilthoven, Netherlands. Natl Inst Water & Atmospher Res, Lauder, New Zealand. RP Tsou, JJ (reprint author), NASA, LaRC, MS 401A, Hampton, VA 23618 USA. EM j.j.tsou@larc.nasa.gov; b.connor@niwa.cri.nz; parrish@astro.umass.edu; r.b.pierce@larc.nasa.gov; i.boyd@niwa.cri.nz; g.bodeker@niwa.cri.nz; w.p.chu@larc.nasa.gov; jmr@hamptonu.edu; daan.swart@rivm.nl; t.j.mcgee@gsfc.nasa.gov RI Pierce, Robert Bradley/F-5609-2010; Bodeker, Greg/A-8870-2008; McGee, Thomas/G-4951-2013 OI Pierce, Robert Bradley/0000-0002-2767-1643; Bodeker, Greg/0000-0003-1094-5852; NR 29 TC 7 Z9 8 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 2000 VL 105 IS D19 BP 24263 EP 24281 DI 10.1029/2000JD900292 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 366WM UT WOS:000090029300007 ER PT J AU Cohen, RC Perkins, KK Koch, LC Stimpfle, RM Wennberg, PO Hanisco, TF Lanzendorf, EJ Bonne, GP Voss, PB Salawitch, RJ Del Negro, LA Wilson, JC McElroy, CT Bui, TP AF Cohen, RC Perkins, KK Koch, LC Stimpfle, RM Wennberg, PO Hanisco, TF Lanzendorf, EJ Bonne, GP Voss, PB Salawitch, RJ Del Negro, LA Wilson, JC McElroy, CT Bui, TP TI Quantitative constraints on the atmospheric chemistry of nitrogen oxides: An analysis along chemical coordinates SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID IN-SITU MEASUREMENTS; INDUCED FLUORESCENCE INSTRUMENT; DIODE-LASER SPECTROMETER; NASA ER-2 AIRCRAFT; LOWER STRATOSPHERE; REACTIVE NITROGEN; SULFATE AEROSOLS; 2-DIMENSIONAL MODEL; INSITU MEASUREMENTS; OZONE DEPLETION AB In situ observations of NO2, NO, NOy, ClONO2, OH, O-3, aerosol surface area, spectrally resolved solar radiation, pressure and temperature obtained from the ER-2 aircraft during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) experiments are used to examine the factors controlling the fast photochemistry connecting NO and NO2 and the slower chemistry connecting NOx and HNO3. Our analysis uses "chemical coordinates" to examine gradients of the difference between a model and precisely calibrated measurements to provide a quantitative assessment of the accuracy of current photochemical models. The NO/NO2 analysis suggests that reducing the activation energy for the NO+O-3 reaction by 1.7 kJ/mol will improve model representation of the temperature dependence of the NO/NO2 ratio in the range 215-235 K. The NOx/HNO3 analysis shows that systematic errors in the relative rate coefficients used to describe NOx loss by the reaction OH + NO2 --> HNO3 and by the reaction set NO2+O-3-->NO3; NO2+NO3 --> N2O5; N2O5+H2O --> 2HNO(3) are in error by +8.4% (+30/-45%) (OH + NO2 too fast) in models using the Jet Propulsion Laboratory 1997 recommendations [DeMore et al., 1997]. Models that use recommendations for OH+NO2 and OH+HNO3 based on reanalysis of recent and past laboratory measurements are in error by 1.2% (+30/-45%) (OH + NO2 too slow). The +30%/-45% error limit reflects systematic uncertainties, while the statistical uncertainty is 0.65%. This analysis also shows that the POLARIS observations only modestly constrain the relative rates of the major NOx production reactions HNO3 + OH --> H2O + NO3 and HNO3 + hv --> OH + NO2. Even under the assumption that all other aspects of the model are perfect, the POLARIS observations only constrain the rate coefficient for OH+HNO3 to a range of 65% around the currently recommended value. C1 Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA. Univ Calif Berkeley, Dept Earth & Planetary Sci, Berkeley, CA 94720 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Div Energy & Environm, Berkeley, CA 94720 USA. Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02138 USA. Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA. Univ Colorado, Dept Chem, Boulder, CO 80309 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Div Engn, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. NOAA, Aeron Lab, Boulder, CO 80303 USA. Univ Denver, Dept Mech Engn, Denver, CO 80208 USA. Environm Canada, Downsview, ON M3H 5T4, Canada. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Cohen, RC (reprint author), Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA. EM cohen@cchem.berkeley.edu RI Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Wennberg, Paul/A-5460-2012 OI Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; NR 80 TC 15 Z9 15 U1 0 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 OCT 16 PY 2000 VL 105 IS D19 BP 24283 EP 24304 DI 10.1029/2000JD900290 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 366WM UT WOS:000090029300008 ER PT J AU Freitas, SR Dias, MAFS Dias, PLS Longo, KM Artaxo, P Andreae, MO Fischer, H AF Freitas, SR Dias, MAFS Dias, PLS Longo, KM Artaxo, P Andreae, MO Fischer, H TI A convective kinematic trajectory technique for low-resolution atmospheric models SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AMAZONIAN SQUALL LINES; CUMULUS PARAMETERIZATION; OZONE; TRACE; SIMULATION; EMISSIONS; CHEMISTRY; TRANSPORT; ACCURACY; BRAZIL AB This paper presents a simple methodology to take into account the subgrid effects of wet convective processes to trace vertical motion of air parcels for low-resolution atmospheric models. Such models are used for wind field simulations that serve as input for trajectory models. Air parcels in moist convective regions can thus be vertically transported to the cumulus top level with the short timescale associated with cumulus updrafts. Two cases are presented: wet and dry seasons in Amazonia, showing the differences of trajectories followed by air parcels with and without the methodology. The implications for the interpretation of air chemistry measurements are discussed, and an example using LBA/CLAIRE data is used to point out the usefulness of the convective kinematic trajectory technique presented here. C1 Univ Sao Paulo, Dept Ciencias Atmosfer, BR-05508900 Sao Paulo, Brazil. Univ Sao Paulo, Inst Fis, BR-05508900 Sao Paulo, Brazil. Max Planck Inst Chem, D-55128 Mainz, Germany. RP Freitas, SR (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. EM mafsdia@-model.iag.usp.br RI Freitas, Saulo/A-2279-2012; Leite da Silva Dias, Pedro/H-1183-2016; Andreae, Meinrat/B-1068-2008; Artaxo, Paulo/E-8874-2010 OI Freitas, Saulo/0000-0002-9879-646X; Leite da Silva Dias, Pedro/0000-0002-4051-2962; Andreae, Meinrat/0000-0003-1968-7925; Artaxo, Paulo/0000-0001-7754-3036 NR 36 TC 24 Z9 26 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 2000 VL 105 IS D19 BP 24375 EP 24386 DI 10.1029/2000JD900217 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 366WM UT WOS:000090029300015 ER PT J AU Coppens, D Haddad, ZS AF Coppens, D Haddad, ZS TI Effects of raindrop size distribution variations on microwave brightness temperature calculation SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PHYSICAL PRECIPITATION RETRIEVAL; CLOUD-RADIATION MODEL; SATELLITE MEASUREMENTS; FOUNDATIONS; PROFILES; SPECTRA AB Many current passive-microwave rain-retrieval methods are based on databases built off-line using cloud models: the models are used to simulate rain events, and radiative transfer calculations produce the associated brightness temperatures. The radiative transfer models depend on, among others, the distribution of hydrometeor sizes. The most popular raindrop size distribution (DSD) used in most models is Marshall and Palmer's [1948]. Improvements were proposed later by Sekhon and Srivastava [1971], Willis and Tattelman [1989], and Feingold and Levin [1986]. Using these DSD models, we study the dependence of forward radiative transfer calculations on the hydrometeor size distribution and quantify the uncertainty due to DSD variability. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Coppens, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM zsh@titan.jpl.nasa.gov NR 16 TC 6 Z9 6 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 16 PY 2000 VL 105 IS D19 BP 24483 EP 24489 DI 10.1029/2000JD900226 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 366WM UT WOS:000090029300022 ER PT J AU Pardo, JR Pagani, L Olofsson, G Febvre, P Tauber, J AF Pardo, JR Pagani, L Olofsson, G Febvre, P Tauber, J TI Balloon-borne submillimeter observations of upper stratospheric O-2 and O-3 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID MESOSPHERIC OZONE; GHZ AB A Swedish-French submillimeter telescope consisting on a 60 cm diameter Cassegrain telescope with a liquid helium cooled supraconductor-isolator-supraconductor (SIS) heterodyne receiver flew on September 25th 1997 in the southwest of France. It was carried out by the Pointed InfraRed Observation Gondola (PIROG, 8th flight) to a ceiling altitude of about 39.5 km. The submillimeter thermal emission of molecular oxygen (N-J = 3(2) --> 1(2) rotational resonance at 424.7631 GHz) and ozone (lines: 24(1,23) --> 24(0,24) at 424.846 GHz, 28(2,26) --> 27(3,25) at 425.158 GHz and 17(1,17) --> 16(0,16) at 441.340 GHz) was collected during about 8.5 h. These are the first submillimeter high-resolution observations of molecules in the middle atmosphere obtained by a non-ground-based instrument and will be helpful in preparing future submillimeter limb-sounding missions, like EOS-MLS (NASA) and Odin (Swedish Space Corporation). We present in this paper the calibration of the atmospheric data and their analysis along with some discussions on ozone mixing ratio just above the ceiling altitude of the experiment. Some validations of our results are done by means of comparisons with temperatures and ozone mixing ratios obtained simultaneously at the Observatoire de Haute Provence (OHP) Lidar station, located also in Southern France. The radiative transfer code used in this work to fit the data and retrieve temperature, pressure and ozone mixing ratio has been developed for the Odin mission. This work is an effective test of such a software package. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Observ Paris, DEMIRM, CNRS, URA 336, F-75014 Paris, France. Stockholm Observ, SE-13336 Saltsjobaden, Sweden. Univ Savoie, LAHC, F-7336 Le Bourget du Lac, France. European Space Agcy, Estec, Dept Space Sci, Div Astrophys, NL-2200 AG Noordwijk, Netherlands. RP Pardo, JR (reprint author), CALTECH, George W Downs Lab Phys, MS 320-47, Pasadena, CA 91125 USA. NR 24 TC 10 Z9 10 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD OCT 16 PY 2000 VL 67 IS 2 BP 169 EP 180 DI 10.1016/S0022-4073(99)00232-0 PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 331RX UT WOS:000088033400007 ER PT J AU Kaplinghat, M Knox, L Turner, MS AF Kaplinghat, M Knox, L Turner, MS TI Annihilating cold dark matter SO PHYSICAL REVIEW LETTERS LA English DT Article ID GALAXIES; HALOS AB Structure formation with cold dark matter (CDM) predicts halos with a central density cusp, which are observationally disfavored. If CDM particles have an annihilation cross section sigma upsilon similar to 10(-29)(m/ GeV) cm(2), then annihilations will soften the cusps. We discuss plausible scenarios for avoiding the early Universe annihilation catastrophe that could result from such a large cross section. The predicted scaling of core density with halo mass depends upon the velocity dependence of sigma upsilon, and s-wave annihilation leads to a core density nearly independent of halo mass, which seems consistent with observations. C1 Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Chicago, Enrico Fermi Inst, Dept Phys, Chicago, IL 60637 USA. RP Kaplinghat, M (reprint author), Univ Chicago, Dept Astron & Astrophys, 5640 S Ellis Ave, Chicago, IL 60637 USA. NR 30 TC 114 Z9 114 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD OCT 16 PY 2000 VL 85 IS 16 BP 3335 EP 3338 DI 10.1103/PhysRevLett.85.3335 PG 4 WC Physics, Multidisciplinary SC Physics GA 363YU UT WOS:000089865900001 ER PT J AU Martinez-Fernandez, J Valera-Feria, FM Singh, M AF Martinez-Fernandez, J Valera-Feria, FM Singh, M TI High temperature compressive mechanical behavior of biomorphic silicon carbide ceramics SO SCRIPTA MATERIALIA LA English DT Article DE ceramics; biomaterials; mechanical properties; high temperature; microstructure ID REACTIVE MELT INFILTRATION; RFSC CERAMICS; MICROSTRUCTURE; ALLOYS; WOOD C1 Univ Sevilla, Dept Fis Mat Condensada, E-41080 Seville, Spain. NASA, Glenn Res Ctr, Ceram Branch, Cleveland, OH 44135 USA. RP Martinez-Fernandez, J (reprint author), Univ Sevilla, Dept Fis Mat Condensada, Apdo 1065, E-41080 Seville, Spain. RI MARTINEZ FERNANDEZ, JULIAN/K-1826-2012 OI MARTINEZ FERNANDEZ, JULIAN/0000-0002-1199-6638 NR 10 TC 75 Z9 79 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1359-6462 J9 SCRIPTA MATER JI Scr. Mater. PD OCT 16 PY 2000 VL 43 IS 9 BP 813 EP 818 DI 10.1016/S1359-6462(00)00494-2 PG 6 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 369KR UT WOS:000165064900006 ER PT J AU Crucian, B Sams, C AF Crucian, B Sams, C TI A comparison of whole blood and PBMC culture for assessing monocyte cytokine production by flow cytometry SO CYTOMETRY 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 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 2000 VL 42 IS 5 MA 10 BP 314 EP 315 PG 2 WC Biochemical Research Methods; Cell Biology SC Biochemistry & Molecular Biology; Cell Biology GA 366DG UT WOS:000089989100018 ER PT J AU Thompson, AM Doddridge, BG Witte, JC Hudson, RD Luke, WT Johnston, JE Johnston, BJ Oltmans, SJ Weller, R AF Thompson, AM Doddridge, BG Witte, JC Hudson, RD Luke, WT Johnston, JE Johnston, BJ Oltmans, SJ Weller, R TI A tropical Atlantic paradox: Shipboard and satellite views of a tropospheric ozone maximum and wave-one in January-February 1999. SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MODIFIED-RESIDUAL METHOD AB During the Aerosols99 trans-Atlantic cruise from Norfolk, VA, to Cape Town, South Africa, daily ozonesondes were launched from the R/V Ronald H Brown between 17 January and 6 February 1999. A composite of tropospheric ozone profiles along the latitudinal transect shows 4 zones, nearly identical to the ozone distribution during a January-February 1993 trans-Atlantic cruise [Weller et al., 1996]. Sondes from the cruise and Ascension Island (8S, 14.5W), as well as the Earth-Probe (EP)/TOMS satellite instrument, show elevated tropospheric ozone (> 35 Dobson Units) throughout the south Atlantic in January 1999. Ozone layers associated with biomass burning north of the ITCZ (Intertropical Convergence Zone) are prominent at 0-5 km from 10-0N, but even higher ozone (100 ppbv, 5-15 km) occurred south of the ITCZ, where it was not burning - an ozone "paradox" that contributes to a wave-one zonal pattern in tropospheric ozone. Back trajectories, satellite observations and shipboard tracers suggest that the south Atlantic ozone results from a combination of interhemispheric transport, aged stratospheric-upper tropospheric air, and possibly from ozone supplied by lightning nitric oxide. C1 NASA, Goddard Space Flight Ctr, EITI, Greenbelt, MD 20771 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Univ Washington, NOAA, PMEL, JISAO, Seattle, WA 98115 USA. NOAA, Air Resources Lab, SSMC, Silver Spring, MD 20910 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Alfred Wegener Inst Polar & Marine Res, D-27515 Bremerhaven, Germany. RP Thompson, AM (reprint author), NASA, Goddard Space Flight Ctr, EITI, Code 916, Greenbelt, MD 20771 USA. RI Hudson, Robert/F-4506-2010; Luke, Winston/D-1594-2016; Thompson, Anne /C-3649-2014 OI Luke, Winston/0000-0002-1993-2241; Thompson, Anne /0000-0002-7829-0920 NR 14 TC 92 Z9 92 U1 0 U2 5 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 2000 VL 27 IS 20 BP 3317 EP 3320 DI 10.1029/1999GL011273 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 365RR UT WOS:000089964700022 ER PT J AU O'Neill, NT Ignatov, A Holben, BN Eck, TF AF O'Neill, NT Ignatov, A Holben, BN Eck, TF TI The lognormal distribution as a reference for reporting aerosol optical depth statistics; Empirical tests using multi-year, multi-site AERONET sunphotometer data SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Aerosol optical depth data representative of various types of aerosols was employed to empirically demonstrate that the lognormal probability distribution is a better reference for reporting optical depth statistics than a normal probability distribution. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NOAA, NESDIS, Climate Res & Applicat Div, Camp Springs, MD USA. Univ Sherbrooke, CARTEL, LOA, Sherbrooke, PQ J1K 2R1, Canada. RP O'Neill, NT (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Ignatov, Alexander/F-5594-2010; ECK, THOMAS/D-7407-2012 OI Ignatov, Alexander/0000-0002-7463-5944; NR 9 TC 89 Z9 93 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 OCT 15 PY 2000 VL 27 IS 20 BP 3333 EP 3336 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 365RR UT WOS:000089964700026 ER PT J AU Knupp, KR Walters, J McCaul, EW AF Knupp, KR Walters, J McCaul, EW TI Doppler profiler observations of Hurricane Georges at landfall SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The boundary layer (BL) within the western eye-wall of Hurricane Georges, during its landfall on the Mississippi coastline, is described using measurements from a mobile Doppler profiling system. The turbulent layer depth, roughly proportional to the BL wind magnitude, attained a height of about 2 km above ground level (AGL) during maximum measured winds of 40-45 m s(-1) near 0.5 km attitude. The BL contains updrafts and downdrafts of 1-3 m s(-1) magnitude that may be associated with the vertical branches of horizontal convective rolls or wind streaks recently identified within and falling hurricanes. These turbulent eddies, and the large vertical shear of horizontal winds within the BL above and below the jet maximum within the eyewall, appear to produce a uniform mass concentration of relatively small raindrops within the BL. C1 Univ Alabama, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. RP Knupp, KR (reprint author), NSSTC, Global Hydrol & Climate Ctr, 320 Sparkman Dr, Huntsville, AL 35805 USA. NR 8 TC 8 Z9 8 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 2000 VL 27 IS 20 BP 3361 EP 3364 DI 10.1029/1999GL011260 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 365RR UT WOS:000089964700033 ER PT J AU Collatz, GJ Bounoua, L Los, SO Randall, DA Fung, IY Sellers, PJ AF Collatz, GJ Bounoua, L Los, SO Randall, DA Fung, IY Sellers, PJ TI A mechanism for the influence of vegetation on the response of the diurnal temperature range to changing climate SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SURFACE PARAMETERIZATION SIB2; GENERAL-CIRCULATION MODEL; STOMATAL CONDUCTANCE; MINIMUM TEMPERATURE; ATMOSPHERIC GCMS; CARBON; CO2; PHOTOSYNTHESIS; TRANSPIRATION; VARIABILITY AB We propose a new mechanism that could contribute to the observed decrease in the diurnal temperature range (DTR) over the last century: the physiological behavior of vegetation in response to climate. Using a physiologically based land surface model, we analyze the influence of vegetation on the response of the DTR to perturbations in the state of the climate and vegetation. Increasing down-welling long wave radiation and surface air temperature together, conditions that could occur as a result of doubling of atmospheric CO2, produced little change in the DTR. Changes in the state of the vegetation (i,e, amount, physiological capacity, stress) produce changes in the DTR of the order or larger than observed. Results emphasize that DTR modeling studies need to consider vegetation responses and suggest that recently reported increases in vegetation over the last decade could contribute to the observed decreases in the DTR. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Dept Geol & Geophys, Ctr Atmospher Sci, Berkeley, CA 94720 USA. Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. NASA, Johnson Space Flight Ctr, Houston, TX 77058 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Collatz, GJ (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. RI collatz, george/D-5381-2012; Los, Sietse/G-8985-2012; Randall, David/E-6113-2011; OI Randall, David/0000-0001-6935-4112; Los, Sietse/0000-0002-1325-3555 NR 23 TC 57 Z9 62 U1 0 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 OCT 15 PY 2000 VL 27 IS 20 BP 3381 EP 3384 DI 10.1029/1999GL010947 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 365RR UT WOS:000089964700038 ER PT J AU Delouis, B Lundgren, P Salichon, J Giardini, D AF Delouis, B Lundgren, P Salichon, J Giardini, D TI Joint inversion of InSAR and teleseismic data for the slip history of the 1999 Izmit (Turkey) earthquake SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INTERFEROMETRY; LANDERS AB The slip history of the Izmit earthquake is investigated by jointly inverting SAR and teleseismic data with a multi-segment, variable-slip, finite fault model. Surface offsets are used as an added constraint. The highest slip values (5 to 7 m of right-lateral displacement) are associated with a strong central asperity surrounding the hypocenter. The bilateral breaking of this main asperity, which lasted about 10 sec, dominates the source time function. From the Golcuk-Izmit area to Lake Sapanca, a relatively good correspondence is observed between slip at depth and at the surface, but farther to the West and to the East slip tends to be confined to the near surface. Slip in the easternmost part of the rupture (Duzce segment) is not well resolved. Our analysis finds the InSAR and teleseismic data to be compatible and complementary. This study shows the potential of the joint inversion of both data sets for a rapid determination of the spatio-temporal history of large earthquakes. C1 ETH Honggerberg, Inst Geophys, CH-8093 Zurich, Switzerland. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Delouis, B (reprint author), ETH Honggerberg, Inst Geophys, CH-8093 Zurich, Switzerland. RI Giardini, Domenico/F-5406-2011 NR 10 TC 33 Z9 33 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 2000 VL 27 IS 20 BP 3389 EP 3392 DI 10.1029/2000GL011511 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 365RR UT WOS:000089964700040 ER PT J AU Ho, DT Asher, WE Bliven, LF Schlosser, P Gordan, EL AF Ho, DT Asher, WE Bliven, LF Schlosser, P Gordan, EL TI On mechanisms of rain-induced air-water gas exchange SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID FRESH-WATER; RING-WAVES; WIND-SPEED; OCEAN; FLUX; INTERFACE; BUBBLES; SURFACE; COOL; SKIN AB Previous studies have shown that rain significantly enhances the rate of air-water gas exchange. However, even though an empirical correlation between the rain rate or kinetic energy flux (KEF) delivered to the water surface by rain and the gas transfer velocity has been established, the physical mechanisms underlying the gas exchange enhancement remain unexamined. During a series of experiments, the processes behind rain-induced air-water gas exchange were examined at NASA's Rain-Sea Interaction Facility (RSIF). Gas transfer velocities for helium (He), nitrous oxide (N2O), and sulfur hexafluoride (SF6) were determined for 22 rain rates (13.6 to 115.2 mm h(-1)) and three drop sizes (2.3, 2.8, 4.2 mm). Bubbles generated by the raindrops were characterized using a video-microscope technique, and surface waves were characterized by a capacitance probe. Additionally, rain-generated turbulence was inferred from friction velocities u(*w) calculated from KEF. Together, these data suggest that rain-induced air-water gas exchange is mainly caused by turbulence-driven exchange processes, with bubbles contributing anywhere from 0 to 20%, depending on rain rate, drop size, and the solubility of the gas tracer. Furthermore, the data confirm that the previously selected variable KEF is the best correlate for rain-induced air-water gas exchange. C1 Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA. Columbia Univ, Dept Earth & Environm Sci, Palisades, NY 10964 USA. Univ Washington, Appl Phys Lab, Seattle, WA 98105 USA. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Wallops Island, VA 23337 USA. RP Ho, DT (reprint author), Columbia Univ, Lamont Doherty Earth Observ, Route 9W, Palisades, NY 10964 USA. RI Ho, David/A-3154-2011; Schlosser, Peter/C-6416-2012; bliven, francis/E-1450-2012 OI Ho, David/0000-0002-0944-6952; Schlosser, Peter/0000-0002-6514-4203; NR 38 TC 42 Z9 43 U1 0 U2 10 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 2000 VL 105 IS C10 BP 24045 EP 24057 DI 10.1029/1999JC000280 PG 13 WC Oceanography SC Oceanography GA 364YE UT WOS:000089921000009 ER PT J AU Moller, D Mourad, PD Frasier, SJ AF Moller, D Mourad, PD Frasier, SJ TI Field observations of radar backscatter from the ocean surface under low wind speed conditions SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ARRAY IMAGING RADAR; LOW GRAZING ANGLES; SEA-SURFACE; MICROWAVE BACKSCATTER; BRAGG SCATTERING; WAVES; MODEL; FEATURES; RETURN; SPIKES AB Unique simultaneous field observations of wind speed and images of vertically polarized radar backscatter from the ocean surface at low grazing angles during low wind and weakly stable stratification show interesting similarities and an important difference, depending on whether the average wind is falling or rising. When the wind speed begins to fall, there is a delay before the area-averaged radar backscatter begins to fall. When the wind speed begins to rise, the backscatter rises immediately. This observation points to hysteresis in the relationship between radar backscatter and wind speed such that more wind is necessary to generate radar backscatter of a given intensity than is necessary to maintain it. This likely arises from differences between the generation of wind-driven gravity capillary waves and the maintenance of gravity capillary waves and/or microbores. Also, saturation was observed in the radar backscatter at wind speeds between 2.1 and 2.8 m s(-1) for both rising and falling winds. This saturation may be related to the energetics of the centimeter-scale gravity capillary waves and/or microbores that cause the backscatter. During rising winds the backscatter may saturate because fine-scale features of the ocean surface reach a maximum amplitude well before wind-derived energy is transferred upscale to larger waves, whose tilting effect would ultimately produce the familiar increase in radar backscatter with increasing wind. During falling winds the backscatter may saturate because of residual momentum in the surface wave field. Finally, for both rising and falling winds, radar backscatter and wind speed are, in general, correlated above a wind speed of 1.7 m s(-1), while below this value they are not. This observation of the critical wind speed necessary to generate or maintain wind-related backscatter is consistent with results from a recent field observation and with existing laboratory-based observations. C1 Univ Washington, Appl Phys Lab, Seattle, WA 98105 USA. Univ Massachusetts, Microwave Remote Sensing Lab, Amherst, MA 01003 USA. RP Moller, D (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Frasier, Stephen/H-1536-2015 OI Frasier, Stephen/0000-0003-4287-2889 NR 36 TC 3 Z9 3 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-OCEANS JI J. Geophys. Res.-Oceans PD OCT 15 PY 2000 VL 105 IS C10 BP 24059 EP 24069 DI 10.1029/2000JC900103 PG 11 WC Oceanography SC Oceanography GA 364YE UT WOS:000089921000010 ER PT J AU Fischer, DG AF Fischer, DG TI Subwavelength depth resolution in near-field microscopy SO OPTICS LETTERS LA English DT Article ID OPTICS AB A generalized Radon transform is presented that relates, for the case of an evanescent wave that is incident upon a weakly scattering medium, the homogeneous components of the scattered field to the three-dimensional Fourier transform of the dielectric susceptibility. This relationship is used within the context of total internal reflection microscopy to reconstruct the depth structure of the dielectric susceptibility from simulated scattered field data. (C) 2000 Optical Society of America OCIS codes: 290.3200, 180.6900, 100.3010. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. RP Fischer, DG (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 9 TC 5 Z9 5 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD OCT 15 PY 2000 VL 25 IS 20 BP 1529 EP 1531 DI 10.1364/OL.25.001529 PG 3 WC Optics SC Optics GA 363KM UT WOS:000089834900013 PM 18066268 ER PT J AU Snyder, GJ Caillat, T Fleurial, JP AF Snyder, GJ Caillat, T Fleurial, JP TI Thermoelectric, transport, and magnetic properties of the polaron semiconductor FexCr3-xSe4 SO PHYSICAL REVIEW B LA English DT Article ID THERMAL-CONDUCTIVITY; THERMOPOWER AB The series of compounds FexCr3-xSe4, with 0 less than or equal tox less than or equal to3, has been prepared and various thermoelectric properties measured from 5 to 900 K. Unlike most thermoelectric materials that are band semiconductors with high carrier mobilities, FexCr3-xSe4 are polaronic semiconductors with Hall mobility values, over 100 times smaller. Nevertheless, FexCr3-xSe4 has a surprisingly high thermoelectric figure of merit-within a factor of 5 of state-of-the-art materials. Advantageous as a thermoelectric, FexCr3-xSe4 can be heavily doped both n- and p-type, switching at x=0.75. Although a nearly complete solid solution appears to exist in FexCr3-xSe4, a small but distinct discontinuity was found in the structural and physical properties at x=1.5. The electronic transport measurements are consistent with small polaron conductivity, both in the high-temperature activated region, and low-temperature phonon-assisted hopping region proportional to exp(-T-1/4). The magnetic properties are complex and only an approximate phase diagram is given. Only small discontinuities are observed in the transport data at the magnetic transitions. The thermal conductivity of the solid solutions are relatively low, with a glasslike temperature dependence. The thermoelectric figure of merit (ZT) peaks at compositions of x=0.9 for p-type and about x=0.5 for n-type. The highest ZT value of 0.15 was found in p-type samples at 525 K. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Snyder, GJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 277-207, Pasadena, CA 91109 USA. RI Snyder, G. Jeffrey/E-4453-2011; Snyder, G/I-2263-2015 OI Snyder, G. Jeffrey/0000-0003-1414-8682; NR 30 TC 40 Z9 40 U1 1 U2 20 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 OCT 15 PY 2000 VL 62 IS 15 BP 10185 EP 10193 DI 10.1103/PhysRevB.62.10185 PG 9 WC Physics, Condensed Matter SC Physics GA 365YB UT WOS:000089977100059 ER PT J AU Anno, H Matsubara, K Caillat, T Fleurial, JP AF Anno, H Matsubara, K Caillat, T Fleurial, JP TI Valence-band structure of the skutterudite compounds CoAs3, CoSb3, and RhSb3 studied by x-ray photoelectron spectroscopy SO PHYSICAL REVIEW B LA English DT Article ID LIGHTLY DOPED COSB3; P-TYPE COSB3; TRANSPORT-PROPERTIES; ELECTRONIC-STRUCTURE; SINGLE-CRYSTALS; STATES AB The valence-band structure of CoAs3, CoSb3, and RhSb3 with a skutterudite-type crystal structure has been investigated by x-ray photoelectron spectroscopy. The photoemission spectra are compared with recent density-of-states calculations. Our photoemission spectra results and theoretical results are in good agreement for the energy positions in the metal d states and the pnicogen p states, but relatively large differences are found for the positions in the pnicogen s states. Based on our photoemission spectra, the electronic bonding states and the chemical trends are explained qualitatively in terms of a simple tight-binding model. The double localized and itinerant nature of the metal d states is also discussed in relation to the properties of the skutterudites. The metal d-derived density of states feature is clearly observed at about 1.2-, 1.4-, and 2.4-eV binding energies for CoSb3, CoAs3, and RhSb3, respectively. From the point of View of the crystal-held effects, it can be considered that this d-character band originates predominantly from the d orbitals with T-2g symmetry, while d orbitals with E-g symmetry hybridize strongly with the p orbitals forming the conduction band. Since the t(2g) states are considered to be almost completely filled, corresponding to the zero spin S = 0 state ((1)A(1), t(2g)(6)), most of skutterudites exhibit diamagnetic properties. On the other hand, the slight chemical shifts of the core levels as compared with the pure elements indicate a small charge transfer from metal to pnicogen atoms in the skutterudites, leading to hybridization between metal d states and pnicogen p states. p-d hybridization causes not only a substantial screening of atomic Coulomb interactions at metal sites, but also a strong covalent bonding in these materials. Concerning a particular point of the band structure in skutterudites, our photoemission spectra near the valence-band edge show clear experimental evidence of a small density of states around the Fermi level due to a single band crossing the pseudogap. C1 Sci Univ Tokyo Yamaguchi, Onoda 7560884, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sci Univ Tokyo Yamaguchi, 1-1-1 Daigaku Dori, Onoda 7560884, Japan. EM anno@ed.yama.sut.ac.jp NR 35 TC 39 Z9 40 U1 2 U2 22 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9950 EI 2469-9969 J9 PHYS REV B JI Phys. Rev. B PD OCT 15 PY 2000 VL 62 IS 16 BP 10737 EP 10743 DI 10.1103/PhysRevB.62.10737 PG 7 WC Physics, Condensed Matter SC Physics GA 369GY UT WOS:000165058600027 ER PT J AU New, KCB Choi, DI Centrella, JM MacNeice, P Hug, MF Olson, K AF New, KCB Choi, DI Centrella, JM MacNeice, P Hug, MF Olson, K TI Three-dimensional adaptive evolution of gravitational waves in numerical relativity SO PHYSICAL REVIEW D LA English DT Article ID MASSLESS SCALAR FIELD; MESH REFINEMENT; EQUATIONS; COLLAPSE; 3D AB Adaptive techniques are crucial for successful numerical modeling of gravitational waves from astrophysical sources such as coalescing compact binaries, since the radiation typically has wavelengths much larger than the scale of the sources. We have carried out an important step toward this goal: the evolution of weak gravitational waves using adaptive mesh refinement in the Einstein equations. The 2-level adaptive simulation is compared with unigrid runs at coarse and fine resolution, and is shown to track closely the features of the fine grid run. C1 Drexel Univ, Dept Phys, Philadelphia, PA 19104 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA. Penn State Univ, Ctr Gravitat Phys & Geometry, University Pk, PA 16802 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. RP New, KCB (reprint author), Drexel Univ, Dept Phys, Philadelphia, PA 19104 USA. NR 26 TC 13 Z9 13 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 OCT 15 PY 2000 VL 62 IS 8 AR 084039 DI 10.1103/PhysRevD.62.084039 PG 4 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 365YC UT WOS:000089977200064 ER PT J AU Phillips, NG Hu, BL AF Phillips, NG Hu, BL TI Vacuum energy density fluctuations in Minkowski and Casimir states via smeared quantum fields and point separation SO PHYSICAL REVIEW D LA English DT Article ID WEAKLY INHOMOGENEOUS COSMOLOGIES; EARLY UNIVERSE; SEMICLASSICAL GRAVITY; CURVED SPACETIME; BACK-REACTION; PARTICLE-PRODUCTION; EXPECTATION VALUE; TRACE ANOMALIES; DISSIPATION; ANISOTROPY AB We present calculations of the variance of fluctuations and of the mean of the energy momentum tensor of a massless scalar field for the Minkowski and Casimir vacua as a function of an intrinsic scale defined by a smeared field or by point separation. We point out that, contrary to prior claims, the ratio of variance to mean-squared being of the order unity is not necessarily a good criterion for measuring the invalidity of semiclassical gravity. For the Casimir topology we obtain expressions for the variance to mean-squared ratio is a function of the intrinsic scale (defined by a smeared field) compared to the extrinsic scale (defined by the separation of the plates, or the periodicity of space). Our results make it possible to identify the spatial extent where negative energy density prevails which could be useful for studying quantum field effects in worm holes and baby universes, and for examining the design feasibility of real-life "time machines." For the Minkowski vacuum we find that the ratio of the variance to the mean-squared, calculated from the coincidence limit, is identical to the value of the Casimir case at the same limit for spatial point separation while identical to the value of a hot flat space result with a temporal point separation. We analyze the origin of divergences in the fluctuations of the energy density and discuss choices in formulating a procedure for their removal, thus raising new questions about the uniqueness and even the very meaning of regularization of the energy momentum tensor for quantum fields in curved or even flat spacetimes when spacetime is viewed as having an extended structure. C1 NASA, Goddard Space Flight Ctr, Rayhteon ITSS, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. RP Phillips, NG (reprint author), NASA, Goddard Space Flight Ctr, Rayhteon ITSS, Astron & Solar Phys Lab, Code 685, Greenbelt, MD 20771 USA. EM Nicholas.G.Phillips.1@gsfc.nasa.gov; hub@physics.umd.edu NR 61 TC 32 Z9 32 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 OCT 15 PY 2000 VL 62 IS 8 AR 084017 DI 10.1103/PhysRevD.62.084017 PG 18 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 365YC UT WOS:000089977200042 ER PT J AU Brown, PG Hildebrand, AR Zolensky, ME Grady, M Clayton, RN Mayeda, TK Tagliaferri, E Spalding, R MacRae, ND Hoffman, EL Mittlefehldt, DW Wacker, JF Bird, JA Campbell, MD Carpenter, R Gingerich, H Glatiotis, M Greiner, E Mazur, MJ McCausland, PJA Plotkin, H Mazur, TR AF Brown, PG Hildebrand, AR Zolensky, ME Grady, M Clayton, RN Mayeda, TK Tagliaferri, E Spalding, R MacRae, ND Hoffman, EL Mittlefehldt, DW Wacker, JF Bird, JA Campbell, MD Carpenter, R Gingerich, H Glatiotis, M Greiner, E Mazur, MJ McCausland, PJA Plotkin, H Mazur, TR TI The fall, recovery, orbit, and composition of the Tagish Lake meteorite: A new type of carbonaceous chondrite SO SCIENCE LA English DT Article ID OXYGEN-ISOTOPE; ABUNDANCES; MINERALOGY; ELEMENTS; SAMPLES AB The preatmospheric mass of the Tagish Lake meteoroid was about 200,000 kilograms. Its calculated orbit indicates affinity to the Apollo asteroids with a semimajor axis in the middle of the asteroid belt, consistent with a linkage to low-albedo C, D, and P type asteroids. The mineralogy, oxygen isotope, and bulk chemical composition of recovered samples of the Tagish Lake meteorite are intermediate between CM and Cl meteorites. These data suggest that the Tagish Lake meteorite may be one of the most primitive solar system materials yet studied. C1 Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada. Univ Western Ontario, Dept Philosophy, London, ON N6A 3K7, Canada. Univ Calgary, Dept Geol & Geophys, Calgary, AB T2N 1N4, Canada. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Nat Hist Museum, Dept Mineral, London SW7 5BD, England. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Dept Chem, Chicago, IL 60637 USA. Univ Chicago, Dept Geophys Sci, Chicago, IL 60637 USA. ET Space Syst, Camarillo, CA 93012 USA. Sandia Natl Labs, Org 5909, Albuquerque, NM 87185 USA. Univ Western Ontario, Dept Earth Sci, London, ON N6A 5B7, Canada. Activat Labs Ltd, Ancaster, ON L9G 4V5, Canada. Lockheed Martin SO, Houston, TX 77058 USA. Pacific NW Natl Lab, Richland, WA 99352 USA. RP Brown, PG (reprint author), Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada. OI Grady, Monica/0000-0002-4055-533X NR 30 TC 161 Z9 162 U1 3 U2 18 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 OCT 13 PY 2000 VL 290 IS 5490 BP 320 EP 325 DI 10.1126/science.290.5490.320 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 363CW UT WOS:000089818100039 PM 11030647 ER PT J AU Rummel, JD AF Rummel, JD TI Survival on the edge: the tube worm's strategy SO NATURE LA English DT Letter C1 NASA, Washington, DC 20546 USA. RP Rummel, JD (reprint author), NASA, Washington, DC 20546 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 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 12 PY 2000 VL 407 IS 6805 BP 671 EP 671 DI 10.1038/35037802 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 362JB UT WOS:000089773900014 PM 11048696 ER PT J AU Cruikshank, DP AF Cruikshank, DP TI Comet science: The study of remnants from the birth of the solar system SO NATURE LA English DT Book Review C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Cruikshank, DP (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 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 12 PY 2000 VL 407 IS 6805 BP 675 EP 676 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 362JB UT WOS:000089773900017 ER PT J AU Banerjee, PP Gad, E Hudson, T McMillen, D Abdeldayem, H Frazier, D Matsushita, K AF Banerjee, PP Gad, E Hudson, T McMillen, D Abdeldayem, H Frazier, D Matsushita, K TI Edge enhancement and edge-enhanced correlation with photorefractive polymers SO APPLIED OPTICS LA English DT Article ID JOINT TRANSFORM CORRELATOR; BI12SIO20; COMPOSITE; CRYSTALS; GRATINGS AB We demonstrate a simple all-optical realization of programmable edge enhancement and edge-enhanced correlation using novel photorefractive polymers. We show that the higher non-Bragg order in a two-beam coupling scheme contains the edge enhancement of the object when placed in the path of one of the incident beams. Also, this arrangement provides a scheme for writing joint transform correlation dynamic holograms, which can be read by a third beam. The correlation is edge enhanced, and the correlation peak increases with the applied bias voltage. Numerical results without and with beam fanning are presented. Theoretical predictions are reconciled with experimental results. (C) 2000 Optical Society of America. OCIS codes: 190.5330, 190.7070, 100.2980, 100.4550, 090.2900. C1 Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA. USA Space & Missile Def Command, Space & Missile Defense Command TC E, Huntsville, AL 35807 USA. Aviat & Missile Command, Weapon Sci Directorate, Redstone Arsenal, AL 35898 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Osaka City Univ, Osaka 558, Japan. RP Banerjee, PP (reprint author), Univ Dayton, Dept Elect & Comp Engn, Dayton, OH 45469 USA. EM Partha.Banerjee@notes.udayton.edu NR 38 TC 20 Z9 20 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 OCT 10 PY 2000 VL 39 IS 29 BP 5337 EP 5346 DI 10.1364/AO.39.005337 PG 10 WC Optics SC Optics GA 362JR UT WOS:000089775300008 PM 18354530 ER PT J AU Teplitz, HI Malkan, MA Steidel, CC McLean, IS Becklin, EE Figer, DF Gilbert, AM Graham, JR Larkin, JE Levenson, NA Wilcox, MK AF Teplitz, HI Malkan, MA Steidel, CC McLean, IS Becklin, EE Figer, DF Gilbert, AM Graham, JR Larkin, JE Levenson, NA Wilcox, MK TI Measurement of [O III] emission in Lyman-break galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : evolution; galaxies : ISM; galaxies : starburst; infrared : galaxies ID HIGH-REDSHIFT GALAXIES; HUBBLE DEEP FIELD; BAND IMAGING SURVEY; LINE GALAXIES; POPULATION; COLORS; SPECTROSCOPY; EXTRACTION; PHOTOMETRY; ABUNDANCES AB Measurements of [O III] emission in Lyman-break galaxies (LBGs) at z > 3 are presented. Four galaxies were observed with narrowband filters using the near-IR camera on the Keck I 10 m telescope. A fifth galaxy was observed spectroscopically during the commissioning of NIRSPEC, the new infrared spectrometer on Keck II. The emission-line spectrum is used to place limits on the metallicity. Comparing these new measurements with others available from the literature, we find that strong oxygen emission in LBGs may suggest subsolar metallicity for these objects. The [O III] lambda 5007 line is also used to estimate the star formation rate (SFR) of the LBGs. The inferred SFRs are higher than those estimated from the UV continuum, and may be evidence for dust extinction. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. RP Teplitz, HI (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 40 TC 43 Z9 44 U1 0 U2 0 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 2000 VL 542 IS 1 BP 18 EP 26 DI 10.1086/309539 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365ME UT WOS:000089954400003 ER PT J AU Lufkin, EA Sarazin, CL White, RE AF Lufkin, EA Sarazin, CL White, RE TI Time dependence of the mass accretion rate in cluster cooling flows SO ASTROPHYSICAL JOURNAL LA English DT Article DE cooling flows; galaxies : clusters : general; hydrodynamics; intergalactic medium; X-rays : general ID EVOLUTION; GALAXIES; MODELS; PROFILE; PLASMA; WAVES; CODE; GAS AB We analyze two time-dependent cluster cooling flow models in spherical symmetry. The first assumes that the intracluster gas resides in a static external potential and includes the effects of optically thin radiative cooling and mass deposition. This corresponds to previous steady state cooling flow models calculated by White & Sarazin in 1987. Detailed agreement is found between steady state models and time-dependent models at fixed times in the simulations. The mass accretion rate (M)over dot is found either to increase or to remain nearly constant once flows reach a steady state. The time rate of change of (M)over dot is strongly sensitive to the value of the mass deposition parameter q but only mildly sensitive to the ratio beta of gravitational binding energy to gas temperature. We show that previous scaling arguments presented by Bertschinger in 1988 and by White in the same year are valid only for mature cooling flows with weak mass deposition (q less than or similar to 1). The second set of models includes the effects of a secularly deepening cluster potential and secondary infall of gas from the Hubble how. We find that such heating effects do not prevent the flows from reaching a steady state within an initial central cooling time. C1 Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Lufkin, EA (reprint author), Univ Virginia, Dept Astron, POB 3818, Charlottesville, VA 22903 USA. NR 36 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2000 VL 542 IS 1 BP 94 EP 105 DI 10.1086/309528 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365ME UT WOS:000089954400010 ER PT J AU Awaki, H Ueno, S Taniguchi, Y Weaver, KA AF Awaki, H Ueno, S Taniguchi, Y Weaver, KA TI X-ray emission from Seyfert 2 galaxies with optical polarized broad lines SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Markarian 3; Markarian 348, Markarian 477, Markarian 1210; NGC 7212, Was 49b); galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; ASCA OBSERVATIONS; SPECTRUM; REFLECTION; REGIONS; SPECTROPOLARIMETRY; ABSORPTION; LUMINOSITY; VELOCITIES; NGC-1068 AB We analyze the 0.5-10 keV spectra of six Seyfert 2 galaxies observed with the X-ray satellite ASCA: Mrk 3, Mrk 348, Mrk 1210, Mrk 477, NGC 7212, and Was 49b. These galaxies were selected based on their possession of optical polarized broad lines. In the 2-10 keV band, their spectra are heavily absorbed, with 2-10 keV absorption-corrected X-ray luminosities ranging from 10(42) to 10(43) ergs s(-1). The observed X-ray emission is generally only about 1/10 that predicted based on their known infrared and HE luminosities. This apparent X-ray weakness can be understood if a considerable fraction of the nuclear activity is completely blocked from view by thick matter along our line of sight to the nucleus. All of these galaxies possess significant soft X-ray emission whose origin appears to be scattered light from their nuclear emission. Based on this hypothesis, we estimate a typical scattering efficiency for X-rays to be about 10%. This efficiency is larger than the few percent found for ordinary Seyfert 2 galaxies with no report of optical polarized broad lines. A large scattering efficiency is best explained by an apparent weakness of the hard X-ray luminosity rather than unusually strong scattered light in the soft band. When we estimate the scattering efficiency using the intrinsic luminosity derived assuming that Compton scattering dominates the hard X-ray spectrum, as opposed to a purely absorbed nuclear continuum, the efficiency can be less and is similar to that of ordinary Seyfert 2 galaxies. Since the difference between our sample and ordinary Seyfert 2 galaxies can be explained by the difference of viewing angle, the similar scattering efficiency suggests the existence of a scattering region that is larger than the putative dusty torus. C1 Kyoto Univ, Fac Sci, Dept Phys, Sakyo Ku, Kyoto 6068502, Japan. Natl Space Dev Agcy Japan, Tsukuba Space Ctr, Space Utilizat Res Program, Tsukuba, Ibaraki 3058505, Japan. Tohoku Univ, Grad Sch Sci, Astron Inst, Aoba Ku, Sendai, Miyagi 9808578, Japan. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Awaki, H (reprint author), Ehime Univ, Fac Sci, Dept Phys, Matsuyama, Ehime 7908577, Japan. NR 47 TC 49 Z9 49 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2000 VL 542 IS 1 BP 175 EP 185 DI 10.1086/309516 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365ME UT WOS:000089954400017 ER PT J AU Akerlof, C Balsano, R Barthelmy, S Bloch, J Butterworth, P Casperson, D Cline, T Fletcher, S Gisler, G Hills, J Kehoe, R Lee, B Marshall, S McKay, T Pawl, A Priedhorsky, W Seldomridge, N Szymanski, J Wren, J AF Akerlof, C Balsano, R Barthelmy, S Bloch, J Butterworth, P Casperson, D Cline, T Fletcher, S Gisler, G Hills, J Kehoe, R Lee, B Marshall, S McKay, T Pawl, A Priedhorsky, W Seldomridge, N Szymanski, J Wren, J TI Rapid optical follow-up observations of SGR events with ROTSE-I SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; gamma rays : observations; pulsars : individual (SGR 1900+14; SGR 1806-20) ID GAMMA-RAY BURST; MAGNETIZED NEUTRON-STARS; HIGH-ENERGY TRANSIENT; REPEATER SGR1900+14; PULSAR; IDENTIFICATION; EXTINCTION; SGR1806-20; COINCIDENT; OUTBURST AB In order to observe nearly simultaneous emission from gamma-ray bursts (GRBs), the Robotic Optical Transient Search Experiment (ROTSE) receives triggers via the GRB Coordinates Network (GCN). Since beginning operations in 1998 March, ROTSE has also taken useful data for 10 SGR events: eight from SGR 1900 + 14 and two from SGR 1806-20. We have searched for new or variable sources in the error regions of these SGRs, and no optical counterparts were observed. Limits are in the range m(ROTSE) approximate to 12.5-15.5 during the period 20 s to 1 hr after the observed SGR events. C1 Univ Michigan, Ann Arbor, MI 48109 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. RP Akerlof, C (reprint author), Univ Michigan, Ann Arbor, MI 48109 USA. RI Barthelmy, Scott/D-2943-2012; McKay, Timothy/C-1501-2009; OI McKay, Timothy/0000-0001-9036-6150; Priedhorsky, William/0000-0003-0295-9138 NR 41 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2000 VL 542 IS 1 BP 251 EP 256 DI 10.1086/309535 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365ME UT WOS:000089954400025 ER PT J AU Leahy, DA Marshall, H Scott, DM AF Leahy, DA Marshall, H Scott, DM TI EUVE observations of Hercules X-1 during a short high-state turn-on SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : eclipsing; stars : individual (HZ Herculis, Hercules X-1); stars : neutron ID TELESCOPE OBSERVATIONS; SPECTRUM; BEPPOSAX; CYCLE AB Observations of Hercules X-l by the Extreme Ultraviolet Explorer (EUVE) covering low state and the early part of the short high state are reported here. This is the first EUV observation of this part of the 35 day cycle of Her X-l. The low-state portion of the EUV light curve (prior to the start of the short high state) has similar properties as that following the end of the short high state : This is evidence that the low-state EW emission is primarily due to EUV reflection from the companion star HZ Her. The EUV light curve during the short high state is pulsed and closely resembles the average 2-12 keV X-ray short high-state light curve, indicating that the EUV emission, like the X-ray emission, originates near the neutron star. The short high-state EUV spectrum is consistent with a blackbody of temperature similar or equal to0.13 keV and radius similar or equal to 230 km, The short high-state EUV spectrum and pulse shape are similar to that in the soft X-rays (0.1-1 keV). The most likely origin of the EUV emission is reprocessed X-rays from the inner edge of the accretion disk, and the radius of the inner edge of the accretion disk is likely to be small, consistent with that determined from analysis of the X-ray pulse shape evolution. C1 Univ Calgary, Dept Phys, Calgary, AB T2N 1N4, Canada. MIT, Cambridge, MA 02139 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Directorate, Huntsville, AL 35812 USA. RP Leahy, DA (reprint author), Univ Calgary, Dept Phys, Calgary, AB T2N 1N4, Canada. NR 30 TC 18 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2000 VL 542 IS 1 BP 446 EP 452 DI 10.1086/309507 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365ME UT WOS:000089954400043 ER PT J AU Gotthelf, EV Vasisht, G Boylan-Kolchin, M Torii, K AF Gotthelf, EV Vasisht, G Boylan-Kolchin, M Torii, K TI A 700 year-old pulsar in the supernova remnant Kesteven 75 SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : individual (PSR J1846-0258); stars : individual (AX J184624.5-025828); stars : neutron; supernovae : individual (Kesteven 75); X-rays : general ID X-RAY; NEUTRON-STARS; G29.7-0.3; EMISSION AB Since their discovery 30 years ago, pulsars have been understood to be neutron stars born rotating rapidly (similar to 10-100 ms). These neutron stars are thought to be created in supernova explosions involving massive stars, which give rise to expanding supernova remnants (SNRs). With over 220 Galactic SNRs known and over 1200 radio pulsars detected, it is quite surprising that few associations between the two populations have been identified with any certainty. Here we report the discovery of a remarkable 0.8 s X-ray pulsar, PSR J1846-0258, associated with the supernova remnant Kes 75. With a characteristic age of only 723 yr, consistent with the age of Kes 75, PSR J1846-0258 is the youngest pulsar yet discovered and is being rapidly spun down by torques from a large magnetic dipole with a strength of similar or equal to5 x 10(13) G, just above the so-called quantum critical field. PSR J1846-0258 resides in this transitional regime where the magnetic field is hypothesized to separate the regular pulsars from the so-called magnetars. PSR J1846-0258 is evidently a rotation-powered pulsar like the Crab; however, its period, spin-down rate, and spin-down energy-to-X-ray luminosity conversion efficiency are each an order of magnitude greater, likely the consequence of its extreme magnetic field. C1 Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Space Dev Agcy Japan, Tsukuba Space Ctr, Space Utilizat Res Program, Tsukuba, Ibaraki 3058505, Japan. RP Gotthelf, EV (reprint author), Columbia Univ, Columbia Astrophys Lab, 550 W 120th St, New York, NY 10027 USA. NR 26 TC 86 Z9 86 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2000 VL 542 IS 1 BP L37 EP L40 DI 10.1086/312923 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365MF UT WOS:000089954500010 ER PT J AU Michael, E McCray, R Pun, CSJ Garnavich, P Challis, P Kirshner, RP Raymond, J Borkowski, K Chevalier, R Filippenko, AV Fransson, C Lundqvist, P Panagia, N Phillips, MM Sonneborn, G Suntzeff, NB Wang, LF Wheeler, JC AF Michael, E McCray, R Pun, CSJ Garnavich, P Challis, P Kirshner, RP Raymond, J Borkowski, K Chevalier, R Filippenko, AV Fransson, C Lundqvist, P Panagia, N Phillips, MM Sonneborn, G Suntzeff, NB Wang, LF Wheeler, JC TI Hubble Space Telescope spectroscopy of spot 1 on the circumstellar ring of SN 1987A SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; shock waves; supernova remnants; supernovae : individual (SN 1987A) ID MAGELLANIC CLOUDS; RADIATIVE SHOCKS; LINE EMISSION; SN-1987A; PROGENITOR; ABUNDANCES; WAVES AB We present ultraviolet and optical spectra of the first bright spot (P.A. = 29 degrees) on SN 1987A's equatorial circumstellar ring taken with the Space Telescope Imaging Spectrograph. We interpret this spot as the emission produced by radiative shocks that occur where the supernova blast wave strikes an inward protrusion of the ring. The observed line widths and intensity ratios indicate the presence of radiative shocks with velocities ranging from 100 to 250 km s(-1) entering dense (greater than or similar to 10(4) cm(-3)) gas. These observations, and future observations of the development of the spectra and line profiles, provide a unique opportunity to study the hydrodynamics of radiative shocks. C1 Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Lab Astron & Space Phys, Greenbelt, MD 20771 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. N Carolina State Univ, Dept Phys, Raleigh, NC 27695 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Stockholm Observ, SE-13336 Saltsjobaden, Sweden. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Observ Carnegie Inst Washington, Observ Las Campanas, La Serena, Chile. Natl Opt Astron Observ, Cerro Tololo Interamer Observ, La Serena, Chile. Univ Texas, Dept Astron, Austin, TX 78712 USA. RP Michael, E (reprint author), Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. EM michaele@colorado.edu NR 24 TC 37 Z9 37 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2000 VL 542 IS 1 BP L53 EP L56 DI 10.1086/312924 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365MF UT WOS:000089954500014 ER PT J AU Vasisht, G Gotthelf, EV Torii, K Gaensler, BM AF Vasisht, G Gotthelf, EV Torii, K Gaensler, BM TI Detection of a compact X-ray source in the supernova remnant G29.6+0.1: A variable anomalous X-ray pulsar? SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (G29.6+0.1); pulsars : individual (AX J1845-0258); stars : individual (AX J184453-025640); stars : neutron ID NEUTRON-STAR; DISCOVERY AB We present follow-up observations of the serendipitously discovered 7 s X-ray pulsar AX J1845-0258, which displays characteristics similar to those observed in the anomalous X-ray pulsars (AXPs). We find a dramatic reduction in its 3-10 keV flux in both new ASCA and Rossi X-Ray Timing Explorer data sets. Within the pulsar's position error locus, we find a faint point source, AX J184453-025640, surrounded by an are of diffuse X-ray emission. This are is coincident with the southeast quadrant of the radio shell of the newly discovered supernova remnant G29.6+/-0.1, recently reported by Gaensler et al. Lack of sufficient flux from the source prevents us from confirming the 7 s pulsed emission observed in the bright state; hence, at present we cannot definitively resolve whether AX J1845-0258 and AX J184453-025640 are one and the same. If they are the same, then the peak-to-peak luminosity changes recorded for AX J1845-0258 may be larger than seen in other AXPs; closer monitoring of this pulsar might lead to a resolution on the mechanism that drives AXPs. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. Natl Space Dev Agcy, Tsukuba Space Ctr, Space Utilizat Res Program, Tsukuba, Ibaraki 3058505, Japan. RP Vasisht, G (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Gaensler, Bryan/F-8655-2010 NR 26 TC 33 Z9 34 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 10 PY 2000 VL 542 IS 1 BP L49 EP L52 DI 10.1086/312910 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 365MF UT WOS:000089954500013 ER PT J AU Hariharan, SI Scott, JR Kreider, KL AF Hariharan, SI Scott, JR Kreider, KL TI A potential-theoretic method for far-field sound radiation calculations SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE compressible flows; aeroacoustics; singular integral equations; far-field calculations ID FINITE-DIFFERENCE; COMPUTATIONAL AEROACOUSTICS; BOUNDARY-CONDITIONS; ACOUSTICS; JET AB The far-field acoustic radiation due to the interaction of upstream, unsteady vortical disturbances with an airfoil in subsonic, compressible flow is calculated using potential theory. A Kirchhoff surface is placed in the near field surrounding the airfoil and the pressure on this surface is calculated from the unsteady flow field, obtained using a second-order finite-difference code. The governing equation is reduced to the Helmholtz equation in the frequency domain and the solution is written in terms of an integral over the Kirchhoff surface involving the free-space Green's function and an unknown single-layer density function. The single-layer density is then determined from the boundary condition on the Kirchhoff surface. This method is presented as an alternative to classical Kirchhoff methods. It has the advantage of bring able to accommodate arbitrarily shaped Kirchhoff surfaces and is also readily extendable to three-dimensional problems. Numerical results are presented for thin, symmetric, and loaded airfoils. Thin-airfoil results are compared to the analytical solution, and thick-airfoil results are checked for numerical convergence and compared to results obtained from a time-domain Euler solver. (C) 2000 Academic Press. C1 Univ Akron, Dept Math & Comp Sci, Akron, OH 44325 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Hariharan, SI (reprint author), Univ Akron, Dept Math & Comp Sci, Akron, OH 44325 USA. NR 25 TC 5 Z9 5 U1 0 U2 0 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 2000 VL 164 IS 1 BP 143 EP 164 DI 10.1006/jcph.2000.6591 PG 22 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 367HJ UT WOS:000090055400008 ER PT J AU Weichman, PB Glazman, RE AF Weichman, PB Glazman, RE TI Passive scalar transport by travelling wave fields SO JOURNAL OF FLUID MECHANICS LA English DT Article ID SCALING EXPONENTS; GRAVITY-WAVES; TURBULENCE; EQUILIBRIUM; DIFFUSION; WIND; SEA AB We study turbulent transport of passive tracers by random wave fields of a rather general nature. A formalism allowing for spatial inhomogeneity and anisotropy of an underlying velocity field (such as that caused by a latitudinally varying Coriolis parameter) is developed, with the aim of treating problems of large-scale ocean transport by long internal waves. For the special case of surface gravity waves on deep water, our results agree with the earlier theory of Herterich & Hasselmann (1982), though even in that case we discover additional, off-diagonal elements of the diffusion tensor emerging in the presence of a mean drift. An advective diffusion equation including all components of the diffusion tensor D plus a mean, Stokes-type drift u is derived and applied to the case of baroclinic inertia-gravity (BIG) waves. This application is of particular interest for ocean circulation and climate modelling, as the mean drift, according to our estimates, is comparable to ocean interior currents; Furthermore, while on the largest (100 km and greater) scales, wave-induced diffusion is found to be generally small compared to classical eddy-induced diffusion, the two become comparable on scales below 10 km. These scales are near the present limit on the spatial resolution of eddy-resolving ocean numerical models. Since we find that u(z) and D-zz vanish identically, net vertical transport is absent in wave systems of this type. However, for anisotropic wave spectra the diffusion tensor can have non-zero off-diagonal vertical elements, D-xz and D-yz, and it is shown that their presence leads to non-positive definiteness of D, and a negative diffusion constant is found along a particular principal axis. However, the simultaneous presence of a depth-dependent mean horizontal drift rc(z) eliminates any potential unphysical behaviour. C1 Blackhawk Geometr, Golden, CO 80401 USA. CALTECH, Jet Prop Lab 300 323, Pasadena, CA 91109 USA. RP Weichman, PB (reprint author), Blackhawk Geometr, 301 Commercial Rd,Suite B, Golden, CO 80401 USA. NR 34 TC 13 Z9 13 U1 0 U2 6 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 EI 1469-7645 J9 J FLUID MECH JI J. Fluid Mech. PD OCT 10 PY 2000 VL 420 BP 147 EP 200 DI 10.1017/S0022112000001452 PG 54 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 361TQ UT WOS:000089740500006 ER PT J AU Wright, R Rothery, DA Blake, S Pieri, DC AF Wright, R Rothery, DA Blake, S Pieri, DC TI Improved remote sensing estimates of lava flow cooling: A case study of the 1991-1993 Mount Etna eruption SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID TRACK SCANNING RADIOMETER; KILAUEA VOLCANO; THERMAL BUDGET; LASCAR VOLCANO; INFRARED DATA; TIME-SERIES; HAWAII; SURFACES; SENSOR; TUBES AB Infrared radiance data acquired by the Landsat thematic mapper (TM) provide information regarding the thermal state of active lavas, which can be used to estimate flow surface temperatures and thus lava cooling. Saturation of one or both of TM's short-wave infrared (SWIR) wavebands has meant, however, that previous studies of lava flow cooling have approximated what is almost certainly an n thermal component now surface temperature distribution (where n > 1), with a single pixel-integrated temperature (PIT). We show that the high sensitivity of TM's SWIR wavebands to the small amount of high-temperature (e.g., similar to 1000 degrees C) material exposed in hot fractures within the flows cooler (e.g., similar to 200 degrees C) surface crust results in the calculation of PITs that are higher than the temperature of this crust, which is usually the dominant radiative component. This causes heat loss from such pixels to be overestimated. We present adaptations that allow more realistic heat loss estimates to be produced using TM data by assuming that a second high-temperature component contributes to the radiance measured from saturated pixels and by defining an appropriate range for the temperature of the lava crust. By analyzing a suite of five TM images acquired during the 1991-1993 eruption of Mount Etna we present more realistic estimates of how this flow cooled, as well as results that show how the flow regime of the lava evolved over time. The methods we present will continue to be of use as, although the next generation of high spatial resolution sensors such as the Landsat 7 enhanced thematic mapper plus (ETM+) and the Terra advanced space-borne thermal emission and reflection radiometer (ASTER) will be less susceptible to saturation than TM, the problem will still persist. C1 Open Univ, Dept Earth Sci, Milton Keynes MK7 6AA, Bucks, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wright, R (reprint author), Univ Hawaii, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, 2525 Corren Rd, Honolulu, HI 96822 USA. EM wright@pgd.hawaii.edu; d.a.rothery@open.ac.uk; s.blake@open.ac.uk; dave@lithos.jpl.nasa.gov NR 49 TC 22 Z9 22 U1 3 U2 7 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 OCT 10 PY 2000 VL 105 IS B10 BP 23681 EP 23694 DI 10.1029/2000JB900225 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 364MG UT WOS:000089895700022 ER PT J AU Ricca, A Bauschlicher, CW AF Ricca, A Bauschlicher, CW TI The reactions of polycyclic aromatic hydrocarbons with OH SO CHEMICAL PHYSICS LETTERS LA English DT Article AB The OH radical adds to naphthalene and naphthalene cation without a barrier. For the neutrals, the most favorable path for this intermediate is the loss of the OH, and the next most favorable option is the loss of an H atom to form the alcohol. For the cation, the most favorable path appears to be a hydrogen migration followed by the loss of a hydrogen to form the alcohol. The OH at carbon atom 1 is energetically most favorable for both the inital complex and final product. This is true for both the neutrals and cations. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ricca, A (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 9 TC 25 Z9 25 U1 0 U2 5 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 6 PY 2000 VL 328 IS 4-6 BP 396 EP 402 DI 10.1016/S0009-2614(00)00915-5 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 363LE UT WOS:000089836500013 ER PT J AU Pyykko, P Runeberg, N Straka, M Dyall, KG AF Pyykko, P Runeberg, N Straka, M Dyall, KG TI Could uranium(XII)hexoxide, UO(6) (O(h)) exist? SO CHEMICAL PHYSICS LETTERS LA English DT Article ID URANYL AB The formally dodecavalent, octahedral U(XII)O(6) is found to be a local energy minimum at Several theoretical levels, including quasirelativistic single-reference (HF, B3LYP, MP2 and CCSD(T)) and multireference CI approaches. The fully relativistic, single-configuration Dirac-Fock (DF) approach gives similar U-O bond lengths but has one imaginary frequency. In this hypothetical compound the largest formal oxidation state of uranium would be increased from +VI to +XII. (C) 2000 Elsevier Science B.V. C1 Univ Helsinki, Dept Chem, FIN-00014 Helsinki, Finland. NASA, Ames Res Ctr, Computat Chem Branch, Moffett Field, CA 94035 USA. RP Pyykko, P (reprint author), Univ Helsinki, Dept Chem, POB 55,AI Virtasen Aukio 1, FIN-00014 Helsinki, Finland. EM pekka.pyykko@helsinki.fi RI Straka, Michal/E-5246-2011; OI Straka, Michal/0000-0002-7857-4990; Runeberg, Nino/0000-0003-2424-3114 NR 16 TC 16 Z9 16 U1 0 U2 7 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 6 PY 2000 VL 328 IS 4-6 BP 415 EP 419 DI 10.1016/S0009-2614(00)00958-1 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 363LE UT WOS:000089836500016 ER PT J AU Begley, CM Kleis, SJ AF Begley, CM Kleis, SJ TI The fluid dynamic and shear environment in the NASA/JSC rotating-wall perfused-vessel bioreactor SO BIOTECHNOLOGY AND BIOENGINEERING LA English DT Article DE bioreactor design; microgravity culture; low shear culture; rotating-wall vessel; microcarrier ID TISSUE AB The rotating-wall perfused-vessel (RWPV) bioreactor, used for both microgravity and Earth-based cell science experiments, is characterized in terms of the fluid dynamic and fluid shear stress environment. A numerical model of the flow field is developed and verified with laser Doppler velocimeter measurements. The effects of changes in operating conditions, including rotation rates and fluid perfusion rates, are investigated with the numerical model. The operating conditions typically used for ground-based experiments (equal rotation of the inner and outer cylinders) leads to flow patterns with relatively poor mass distribution characteristics. Approximately 50% of the inlet-perfused fluid bypasses the bulk of the fluid volume and flows to the perfusion exit. For operating conditions typical in microgravity, small differential rotation rates between the inner and outer cylinders lead to greatly improved flow distribution patterns and very low fluid shear stress levels over a large percentage of the fluid volume. Differences in flow patterns for the different operating conditions are explored. Large differences in the hydrodynamic environments for operating conditions typical of true microgravity and groundbased "microgravity simulations" are demonstrated. (C) 2000 John Wiley & Sons, Inc. C1 NASA, Lyndon B Johnson Space Ctr, United Space Alliance, Houston, TX 77058 USA. Univ Houston, Dept Mech Engn, Houston, TX 77204 USA. RP Kleis, SJ (reprint author), NASA, Lyndon B Johnson Space Ctr, United Space Alliance, Houston, TX 77058 USA. NR 7 TC 72 Z9 85 U1 2 U2 16 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 USA SN 0006-3592 J9 BIOTECHNOL BIOENG JI Biotechnol. Bioeng. PD OCT 5 PY 2000 VL 70 IS 1 BP 32 EP 40 DI 10.1002/1097-0290(20001005)70:1<32::AID-BIT5>3.0.CO;2-V PG 9 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA 353FM UT WOS:000089264200005 PM 10940861 ER PT J AU Andrews, L Zhou, MF Wang, XF Bauschlicher, CW AF Andrews, L Zhou, MF Wang, XF Bauschlicher, CW TI Matrix infrared spectra and density functional calculations of manganese and rhenium carbonyl neutral and anion complexes SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID TRANSITION-METAL ATOMS; GAUSSIAN-BASIS SETS; SOLID NEON; DIMANGANESE DECACARBONYL; SPECTROSCOPIC DETECTION; CO; MOLECULES; MONOXIDE; MN(CO)5; ENERGY AB Laser-ablated Mn and Re atoms and electrons react with CO upon co-condensation in excess argon and neon to produce carbonyl neutrals and anions. These species are identified through isotopic substitution, CCl4 doping to trap ablated electrons, and density functional theory isotopic frequency calculations. MnCO is identified at 1933.6 cm(-1) in argon and at 1950.7 cm(-1) in neon, which are in agreement with the gas phase 1955 +/- 15 cm(-1) photoelectron measurement. MnCO- is found at 1789.4 cm(-1) in argon and 1807.5 cm(-1) in neon. The Mn(CO)(2) and Re(CO)(2) dicarbonyls are major product absorptions. Annealing to allow further reaction of CO produces higher carbonyls including Mn-2(CO)(10) and Re-2(CO)(10) in solid argon. Argon and neon matrix experiments are compared for both metals. C1 Univ Virginia, Dept Chem, Charlottesville, VA 22904 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Andrews, L (reprint author), Univ Virginia, Dept Chem, Charlottesville, VA 22904 USA. NR 48 TC 28 Z9 28 U1 1 U2 7 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 OCT 5 PY 2000 VL 104 IS 39 BP 8887 EP 8897 DI 10.1021/jp0019431 PG 11 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 361EY UT WOS:000089711000007 ER PT J AU Bauschlicher, CW Ricca, A AF Bauschlicher, CW Ricca, A TI Heats of formation for cyclic C4Fn, n=4-8, and their cations SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article AB Heats of formation for cyclic C4F8 and C4F8+ are determined at the G3MP2 lever. The several decomposition pathways are investigated. The calculations confirm that C4F8+ rearranges and its decomposition is responsible for both the C2F4+ and C3F5+ species observed in experiment. The heats of formation are presented for C4Fn and C4Fn+, n = 4-8. C1 NASA, Ames Res Ctr, Space Technol Div, 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 17 TC 11 Z9 11 U1 1 U2 2 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 OCT 5 PY 2000 VL 104 IS 39 BP 9026 EP 9028 DI 10.1021/jp002135x PG 3 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 361EY UT WOS:000089711000025 ER PT J AU Laval, B Cady, SL Pollack, JC McKay, CP Bird, JS Grotzinger, JP Ford, DC Bohm, HR AF Laval, B Cady, SL Pollack, JC McKay, CP Bird, JS Grotzinger, JP Ford, DC Bohm, HR TI Modern freshwater microbialite analogues for ancient dendritic reef structures SO NATURE LA English DT Article ID LAKE WATER; PRECIPITATION; ALGAE AB Microbialites are organosedimentary structures that can be constructed by a variety of metabolically distinct taxa(1). Consequently, microbialite structures abound in the fossil record, although the exact nature of the biogeochemical processes that produced them is often unknown(2). One such class of ancient calcareous structures(3-5), Epiphyton and Girvanella, appear in great abundance during the Early Cambrian. Together with Archeocyathids, stromatolites and thrombolites, they formed major Cambrian reef belts. To a large extent, Middle to Late Cambrian reefs are similar to Precambrian reefs(6), with the exception that the latter, including terminal Proterozoic reefs(7), do not contain Epiphyton or Girvanella. Here we report the discovery in Pavilion Lake, British Columbia, Canada, of a distinctive assemblage of freshwater calcite microbialites, some of which display microstructures similar to the fabrics displayed by Epiphyton and Girvanella. The morphologies of the modern microbialites vary with depth, and dendritic microstructures of the deep water (>30 m) mounds indicate that they may be modern analogues for the ancient calcareous structures. These microbialites thus provide an opportunity to study the biogeochemical interactions that produce fabrics similar to those of some enigmatic Early Cambrian reef structures. C1 Simon Fraser Univ, Sch Engn Sci, Burnaby, BC V5A 1S6, Canada. Portland State Univ, Dept Geol, Portland, OR 97201 USA. Forest Sci, Nelson Forest Reg, Nelson, BC V1L 4C6, Canada. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. MIT, Cambridge, MA 02139 USA. McMaster Univ, Hamilton, ON L8S 4KL, Canada. RP Cady, SL (reprint author), Simon Fraser Univ, Sch Engn Sci, Burnaby, BC V5A 1S6, Canada. RI Laval, Bernard/J-9861-2012 NR 22 TC 69 Z9 78 U1 5 U2 26 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 5 PY 2000 VL 407 IS 6804 BP 626 EP 629 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 362HP UT WOS:000089772800046 PM 11034210 ER PT J AU Snavely, RA Key, MH Hatchett, SP Cowan, TE Roth, M Phillips, TW Stoyer, MA Henry, EA Sangster, TC Singh, MS Wilks, SC MacKinnon, A Offenberger, A Pennington, DM Yasuike, K Langdon, AB Lasinski, BF Johnson, J Perry, MD Campbell, EM AF Snavely, RA Key, MH Hatchett, SP Cowan, TE Roth, M Phillips, TW Stoyer, MA Henry, EA Sangster, TC Singh, MS Wilks, SC MacKinnon, A Offenberger, A Pennington, DM Yasuike, K Langdon, AB Lasinski, BF Johnson, J Perry, MD Campbell, EM TI Intense high-energy proton beams from petawatt-laser irradiation of solids SO PHYSICAL REVIEW LETTERS LA English DT Article ID HOT-ELECTRONS; PLASMA; VELOCITY; EMISSION; TARGETS; PULSES AB An intense collimated beam of high-energy protons is emitted normal to the rear surface of thin Solid targets irradiated at 1 PW power and peak intensity 3 x 10(20) Wcm(-2). Up to 48 J (12%) of the laser energy is transferred to 2 X 10(13) protons of energy >10 MeV. The energy spectrum exhibits a sharp high-energy cutoff as high as 58 MeV on the axis of the beam which decreases in energy with increasing off axis angle. Proton induced nuclear processes have been observed and used to characterize the beam. C1 Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. GSI Lab, Darmstadt, Germany. Univ Alberta, Edmonton, AB T6G 2G7, Canada. Osaka Univ, ILE, Suita, Osaka 565, Japan. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Roth, M (reprint author), Univ Calif Lawrence Livermore Natl Lab, POB 808, Livermore, CA 94550 USA. RI MacKinnon, Andrew/P-7239-2014; Cowan, Thomas/A-8713-2011 OI MacKinnon, Andrew/0000-0002-4380-2906; Cowan, Thomas/0000-0002-5845-000X NR 27 TC 1053 Z9 1080 U1 9 U2 71 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD OCT 2 PY 2000 VL 85 IS 14 BP 2945 EP 2948 DI 10.1103/PhysRevLett.85.2945 PG 4 WC Physics, Multidisciplinary SC Physics GA 358XA UT WOS:000089581400025 PM 11005974 ER PT J AU Allman, M AF Allman, M TI A Web server's view of the transport layer SO ACM SIGCOMM COMPUTER COMMUNICATION REVIEW LA English DT Article AB This paper presents observations of traffic to and from a particular World-Wide Web server over the course a year and a half. This paper presents a longitudinal look at various network path properties, as well as the implementation status of various protocol options and mechanisms. In particular, this paper considers how World-Wide Web clients utilize TCP connections to transfer web data; the deployment of various TCP and HTTP options; the range of round-trip times observed in the network; packet sizes used for WWW transfers; the implications of the measured advertised window sizes; and the impact of using larger initial congestion window sizes. These properties/mechanisms and their implications are explored. An additional goal of this paper is to provide information to help researchers better simulate and emulate realistic networks. C1 NASA, Glenn Res Ctr, BBN Technol, Cleveland, OH 44135 USA. RP Allman, M (reprint author), NASA, Glenn Res Ctr, BBN Technol, 21000 Brookpk Rd,MS 54-2, Cleveland, OH 44135 USA. EM mallman@grc.nasa.gov NR 37 TC 24 Z9 27 U1 0 U2 1 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 2 PENN PLAZA, STE 701, NEW YORK, NY 10121-0701 USA SN 0146-4833 EI 1943-5819 J9 ACM SIGCOMM COMP COM JI ACM SIGCOMM Comp. Commun. Rev. PD OCT PY 2000 VL 30 IS 5 BP 10 EP 20 DI 10.1145/505672.505674 PG 11 WC Computer Science, Information Systems SC Computer Science GA 463BN UT WOS:000170457100003 ER PT J AU Wilhite, AW Shaw, RJ AF Wilhite, AW Shaw, RJ TI Technology development for high-speed civil transport SO AERONAUTICAL JOURNAL LA English DT Article; Proceedings Paper CT Biennial Congress of the International-Council-of-the-Aeronautical-Sciences CY AUG 28-SEP 01, 2000 CL HARROGATE, ENGLAND SP Int Council Aeronaut Sci AB The National Aeronautics and Space Administration sponsored a joint High-Speed Research Programme with United States airframe and propulsion companies to provide the critical high-risk technologies for a Mach 2-4, 300 passenger civil transport. Laboratory and medium-scale tests provided promising results in meeting both the environmental and economic goals for a future High-Speed Civil Transport. However, before the technologies were integrated at large and full scale, the programme was cancelled because of global economic concerns of the US transport industry. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Wilhite, AW (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ROYAL AERONAUTICAL SOC PI LONDON PA 4 HAMILTON PL, LONDON W1V OBQ, ENGLAND SN 0001-9240 J9 AERONAUT J JI Aeronaut. J. PD OCT PY 2000 VL 104 IS 1040 BP 467 EP 471 PG 5 WC Engineering, Aerospace SC Engineering GA 386VN UT WOS:000166082400005 ER PT J AU Frink, NT Pirzadeh, SZ Parikh, PC Pandya, MJ Bhat, MK AF Frink, NT Pirzadeh, SZ Parikh, PC Pandya, MJ Bhat, MK TI The NASA tetrahedral unstructured software system (TetrUSS) SO AERONAUTICAL JOURNAL LA English DT Article; Proceedings Paper CT Biennial Congress of the International-Council-of-the-Aeronautical-Sciences CY AUG 28-SEP 01, 2000 CL HARROGATE, ENGLAND SP Int Council Aeronaut Sci ID ADVANCING-LAYERS METHOD; TURBULENT FLOWS; GRID GENERATION; EQUATIONS AB The NASA tetrahedral unstructured software system (TetrUSS) was developed during the 1990s to provide a rapid aerodynamic analysis and design capability to applied aerodynamicists. The system comprises of loosely integrated, user-friendly software that enables the application of advanced Euler and Navier-Stokes tetrahedral finite volume technology to complex aerodynamic problems. TetrUSS has matured well because of the generous feedback from many willing users representing a broad cross-section of background and skill levels. This paper presents an overview of the current capabilities of the TetrUSS system along with some representative results from selected applications. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Frink, NT (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 43 TC 25 Z9 26 U1 0 U2 0 PU ROYAL AERONAUTICAL SOC PI LONDON PA 4 HAMILTON PL, LONDON W1V OBQ, ENGLAND SN 0001-9240 J9 AERONAUT J JI Aeronaut. J. PD OCT PY 2000 VL 104 IS 1040 BP 491 EP 499 PG 9 WC Engineering, Aerospace SC Engineering GA 386VN UT WOS:000166082400008 ER PT J AU Miller, JH Tannehill, JC Lawrence, SL AF Miller, JH Tannehill, JC Lawrence, SL TI Parabolized Navier-Stokes algorithm for solving supersonic flows with upstream influences SO AIAA JOURNAL LA English DT Article ID VISCOUS-INVISCID INTERACTION; RELAXATION; EQUATIONS AB A new parabolized Navier-Stokes (PNS) algorithm has been developed to efficiently compute supersonic flows with embedded regions that produce upstream effects. Innovative techniques are used to automatically detect and measure the extent of the embedded regions. Within the embedded regions, the PNS equations are globally iterated to duplicate the results that would be obtained with the complete Navier-Stokes (NS) equations. Once an embedded region is computed, the algorithm returns to the standard space-marching PNS mode until the next embedded region is encountered. This procedure has been successfully incorporated into NASA's upwind PNS code and it has been validated by its application to several two-dimensional test cases. All of these test cases include embedded regions that produce significant upstream effects. The present numerical results are in excellent agreement with previous NS computations and experimental data. In addition, these calculations demonstrate the significant reduction in computer time and storage that can be achieved by the use of this approach. C1 Iowa State Univ, Dept Aerosp Engn & Engn Mech, Ames, IA 50011 USA. NASA, Ames Res Ctr, Integrated Syst Technol Branch, Moffett Field, CA 94035 USA. RP Miller, JH (reprint author), Iowa State Univ, Dept Aerosp Engn & Engn Mech, Ames, IA 50011 USA. NR 47 TC 3 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 2000 VL 38 IS 10 BP 1837 EP 1845 DI 10.2514/2.865 PG 9 WC Engineering, Aerospace SC Engineering GA 358LP UT WOS:000089559800007 ER PT J AU Freund, JB Moin, P AF Freund, JB Moin, P TI Jet mixing enhancement by high-amplitude fluidic actuation SO AIAA JOURNAL LA English DT Article ID EVOLUTION; NOZZLES; NOISE; TABS AB Recent experiments have shown that properly designed high-amplitude, low mass flux pulsed slot jets blowing normal to a jet's shear layer near the nozzle can significantly alter the jet's development. In contrast to commonly used tow-amplitude forcing, this strong excitation appears to overwhelm the turbulence, having nearly the same effect at high and low Reynolds numbers. It can, therefore, be studied in detail by direct numerical simulation. Direct numerical simulations of Mach 0.9, Reynolds number 3.6 X 10(3) jets exhausting into quiescent fluid are conducted. Physically realistic slot jet actuators are included in the simulation by adding localized body-force terms to the governing equations. Three cases are considered in detail: a baseline unforced case and two cases that are forced with flapping modes at Strouhal numbers 0.2 and 0.4. (Sr=0.4 was found to be the most amplified frequency in the unforced case.) Forcing at either frequency causes the jet to expand rapidly in the plane parallel with the actuators and to contract in the plane perpendicular to the actuators, as observed experimentally. It is found that the jet responds closer to the nozzle when forced at Sr = 0.4, but forcing at Sr = 0.2 is more effective at spreading the jet farther downstream. Several different measures of mixing (scalar dissipation, volume integrals of jet fluid mixture fraction, and point measurements of mixture fraction) are considered, and it is shown that by most, but not all, measures forcing at Sr = 0.2 is the more effective of the two at mixing. C1 Univ Calif Los Angeles, Dept Mech & Aerosp Engn, Los Angeles, CA 90095 USA. Stanford Univ, Dept Engn Mech, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Freund, JB (reprint author), Univ Calif Los Angeles, Dept Mech & Aerosp Engn, Los Angeles, CA 90095 USA. RI Freund, Jonathan/A-6409-2014 NR 19 TC 33 Z9 37 U1 3 U2 8 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD OCT PY 2000 VL 38 IS 10 BP 1863 EP 1870 DI 10.2514/2.839 PG 8 WC Engineering, Aerospace SC Engineering GA 358LP UT WOS:000089559800010 ER PT J AU Komarova, SV Ataullakhanov, FI Globus, RK AF Komarova, SV Ataullakhanov, FI Globus, RK TI Bioenergetics and mitochondrial transmembrane potential during differentiation of cultured osteoblasts SO AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY LA English DT Article DE ATP; respiration; glycolysis; bone ID IN-VITRO; TERMINAL DIFFERENTIATION; EXTRACELLULAR-MATRIX; RAT BONE; APOPTOSIS; CELLS; PROLIFERATION; FIBRONECTIN; ADAPTATION; EXPRESSION AB To evaluate the relationship between osteoblast differentiation and bioenergetics, cultured primary osteoblasts from fetal rat calvaria were grown in medium supplemented with ascorbate to induce differentiation. Before ascorbate treatment, the rate of glucose consumption was 320 nmol . h(-1) . 10(6) cells(-1), respiration was 40 nmol . h(-1) . 10(6) cells(-1), and the ratio of lactate production to glucose consumption was similar to 2, indicating that glycolysis was the main energy source for immature osteoblasts. Ascorbate treatment for 14 days led to a fourfold increase in respiration, a threefold increase in ATP production, and a fivefold increase in ATP content compared with that shown in immature cells. Confocal imaging of mitochondria stained with a transmembrane potential-sensitive vital dye showed that mature cells possessed abundant amounts of high-transmembrane-potential mitochondria, which were concentrated near the culture medium-facing surface. Acute treatment of mature osteoblasts with metabolic inhibitors showed that the rate of glycolysis rose to maintain the cellular energy supply constant. Thus progressive differentiation coincided with changes in cellular metabolism and mitochondrial activity, which are likely to play key roles in osteoblast function. C1 Natl Res Ctr Hematol, Moscow 125167, Russia. NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. RP Globus, RK (reprint author), NASA, Ames Res Ctr, Div Life Sci, MS 236-7, Moffett Field, CA 94035 USA. RI Ataullakhanov, Fazoil/J-8076-2012 NR 33 TC 63 Z9 67 U1 0 U2 7 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0363-6143 J9 AM J PHYSIOL-CELL PH JI Am. J. Physiol.-Cell Physiol. PD OCT PY 2000 VL 279 IS 4 BP C1220 EP C1229 PG 10 WC Cell Biology; Physiology SC Cell Biology; Physiology GA 356YR UT WOS:000089472200035 PM 11003602 ER PT J AU Heaton, JT Kobler, JB Goldstein, EA McMahon, TA Barry, DT Hillman, RE AF Heaton, JT Kobler, JB Goldstein, EA McMahon, TA Barry, DT Hillman, RE TI Recurrent laryngeal nerve transposition in guinea pigs SO ANNALS OF OTOLOGY RHINOLOGY AND LARYNGOLOGY LA English DT Article DE alaryngeal speech; artificial larynx; laryngectomy; larynx; prosthesis; recurrent laryngeal nerve ID MYOSIN ATPASE; MUSCLES; REINNERVATION; FIBERS; RAT AB Improved control of prosthetic voice aids for laryngectomees might be possible to obtain with residual laryngeal motor nerve signals. We were able to recover motor signals from the recurrent laryngeal nerve (RLN) by transposing it into the ipsilateral denervated stemohyoid muscle (SH) in 8 guinea pigs. Reinnervation was monitored by electromyographic recordings from surface and intramuscular needle electrodes in awake animals. Within 4 to 14 weeks after surgery, all animals demonstrated laryngeal-like motor activity in the reinnervated SH, including activity during respiration, sniffing, swallowing, and/or vocalizing. After 3 to 6 months, the animals were reanesthetized, and nerve stimulation and section experiments confirmed the RLN as the source of reinnervation in all cases. In several animals, activity of the RLN-innervated SH was demonstrated to be correlated with that of contralateral laryngeal muscles. Histochemical analysis of the SH indicated a unilateral transformation from mostly fatigable to mostly fatigue-resistant fiber types ipsilateral to the RLN transposition, a phenotype more typical of laryngeal muscles. Thus, RLN transposition at the time of laryngectomy may be a method for salvaging laryngeal control signals that could be used to control prosthetic voice devices. C1 Harvard Univ, Sch Med, Dept Otol & Laryngol, Boston, MA 02115 USA. Harvard Univ, Dept Engn & Appl Sci, Cambridge, MA 02138 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Heaton, JT (reprint author), Massachusetts Eye & Ear Infirm, Voice & Speech Lab, 243 Charles St, Boston, MA 02114 USA. NR 25 TC 8 Z9 10 U1 1 U2 1 PU ANNALS PUBL CO PI ST LOUIS PA 4507 LACLEDE AVE, ST LOUIS, MO 63108 USA SN 0003-4894 J9 ANN OTO RHINOL LARYN JI Ann. Otol. Rhinol. Laryngol. PD OCT PY 2000 VL 109 IS 10 BP 972 EP 980 PN 1 PG 9 WC Otorhinolaryngology SC Otorhinolaryngology GA 363FP UT WOS:000089824700012 PM 11051439 ER PT J AU Miller, SR Castenholz, RW AF Miller, SR Castenholz, RW TI Evolution of thermotolerance in hot spring cyanobacteria of the genus Synechococcus SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID GRADIENT GEL-ELECTROPHORESIS; MULTIPLE SEQUENCE ALIGNMENT; RNA-DEFINED POPULATIONS; RIBOSOMAL-RNA; MICROBIAL MAT; ESCHERICHIA-COLI; TEMPERATURE; SENSITIVITY; ADAPTATION AB The extension of ecological tolerance limits may be an important mechanism by which microorganisms adapt to novel environments, but it may come at the evolutionary cost of reduced performance under ancestral conditions. We combined a comparative physiological approach with phylogenetic analyses to study the evolution of thermotolerance in hot spring cyanobacteria of the genus Synechococcus. Among the 20 laboratory clones of Synechococcus isolated from collections made along an Oregon hot spring thermal gradient, four different 16S rRNA gene sequences were identified, Phylogenies constructed by using the sequence data indicated that the clones were polyphyletic but that three of the four sequence groups formed a clade. Differences in thermotolerance were observed for clones with different 16S rRNA gene sequences, and comparison of these physiological differences within a phylogenetic framework provided evidence that more thermotolerant lineages of Synechococcus evolved from less thermotolerant ancestors. The extension of the thermal limit in these bacteria was correlated with a reduction in the breadth of the temperature range for growth, which provides evidence that enhanced thermotolerance has come at the evolutionary cost of increased thermal specialization. This study illustrates the utility of using phylogenetic comparative methods to investigate how evolutionary processes have shaped historical patterns of ecological diversification in microorganisms, C1 Univ Oregon, Dept Biol, Eugene, OR 97403 USA. RP Miller, SR (reprint author), NASA, Ames Res Ctr, Mailstop 239-4, Moffett Field, CA 94035 USA. NR 36 TC 81 Z9 85 U1 3 U2 11 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 OCT PY 2000 VL 66 IS 10 BP 4222 EP 4229 DI 10.1128/AEM.66.10.4222-4229.2000 PG 8 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 360CW UT WOS:000089649700008 PM 11010863 ER PT J AU Milman, M Petrick, W AF Milman, M Petrick, W TI A note on the solution to a common thermal network problem encountered in heat-transfer analysis of spacecraft SO APPLIED MATHEMATICAL MODELLING LA English DT Article DE thermal network; homotopy; steady-state solution ID HOMOTOPY METHODS AB A widely used discretization method for modeling thermal systems is the thermal network approach. The network approach is derived from energy balance equations and is equivalent to a particular finite difference discretization of the underlying heat-transfer equation. The steady-state problems that arise in the analysis of spacecraft systems using network models are frequently dominated by radiative transfer, which introduces quartic nonlinearities in the equations. Although these systems are routinely encountered, there has not appeared any detailed analysis of these equations. Questions of existence and uniqueness of solutions and numerical methods for solving the systems have never been addressed in any generality. In this paper, general existence and uniqueness properties of the network equations are established. Globally convergent methods for solving the systems are developed and insight into the relative success of existing methods is given. Numerical examples are presented illustrating the methods. The perspective adopted here is also useful in interdisciplinary applications. A simple example involving thermal control is used to demonstrate this. (C) 2000 Elsevier Science Inc. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Milman, M (reprint author), CALTECH, Jet Prop Lab, M-S 198-138,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI wang, peng/F-5123-2012 NR 20 TC 10 Z9 12 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0307-904X J9 APPL MATH MODEL JI Appl. Math. Model. PD OCT PY 2000 VL 24 IS 12 BP 861 EP 879 DI 10.1016/S0307-904X(00)00021-4 PG 19 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA 356CR UT WOS:000089427200001 ER PT J AU Hegner, SJ Mc Kevitt, P Norvig, P Wilensky, R AF Hegner, SJ Mc Kevitt, P Norvig, P Wilensky, R TI Editorial intelligent help systems for UNIX: Natural language dialogue SO ARTIFICIAL INTELLIGENCE REVIEW LA English DT Editorial Material C1 Umea Univ, S-90187 Umea, Sweden. Univ Ulster Magee, Derry, North Ireland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. RP Hegner, SJ (reprint author), Umea Univ, S-90187 Umea, Sweden. NR 4 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0269-2821 J9 ARTIF INTELL REV JI Artif. Intell. Rev. PD OCT PY 2000 VL 14 IS 4-5 BP 277 EP 281 DI 10.1023/A:1026709832001 PG 5 WC Computer Science, Artificial Intelligence SC Computer Science GA 381QR UT WOS:000165774900001 ER PT J AU Crenshaw, DM Kraemer, SB Hutchings, JB Bradley, LD Gull, TR Kaiser, ME Nelson, CH Ruiz, JR Weistrop, D AF Crenshaw, DM Kraemer, SB Hutchings, JB Bradley, LD Gull, TR Kaiser, ME Nelson, CH Ruiz, JR Weistrop, D TI A kinematic model for the narrow-line region in NGC 4151 SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 4151); galaxies : Seyfert ID ACTIVE GALACTIC NUCLEI; NGC-4151; NGC-1068 AB We present a simple kinematic model for the narrow-line region (NLR) of the Seyfert 1 galaxy NGC 4151, based on our previous observations of extended [O mIII] emission with the Space Telescope Imaging Spectrograph. The model is similar to a biconical radial out outflow model developed for the Seyfert 2 galaxy NGC 1068, except that the bicone axis is tilted much more into our line of sight (40 degrees out of the plane of the sky instead of 5 degrees), and the maximum space velocities are lower (750 km s(-1) instead of 1300 km s(-1)). We find evidence for radial acceleration of the emission-line knots to a distance of 160 pc, followed by deceleration that approaches the systemic velocity at a distance of 290 pc (for a distance to NGC 4151 of 13.3 Mpc). Other similarities to the kinematics of NGC 1068 are (1) there are a number of high-velocity clouds that are not decelerated, suggesting that the medium responsible for the deceleration is patchy, and (2) the bicone in NGC 4151 is at least partially evacuated along its axis. Together, these two Seyfert galaxies provide strong evidence for radial outflow (e.g., due to radiation and/or wind pressure) and against gravitational motion or expansion away from the radio jets as the principal kinematic component in the NLR. C1 Catholic Univ Amer, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Res Council Canada, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Nevada, Dept Phys, Las Vegas, NV 89154 USA. RP Crenshaw, DM (reprint author), Catholic Univ Amer, Washington, DC 20064 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 24 TC 86 Z9 86 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 2000 VL 120 IS 4 BP 1731 EP 1738 DI 10.1086/301574 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 364GQ UT WOS:000089884400012 ER PT J AU Hurt, RL Jarrett, TH Kirkpatrick, JD Cutri, RM Schneider, SE Skrutskie, M van Driel, W AF Hurt, RL Jarrett, TH Kirkpatrick, JD Cutri, RM Schneider, SE Skrutskie, M van Driel, W TI Serendipitous 2MASS discoveries near the Galactic Plane: A spiral galaxy and two globular clusters SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : photometry; galaxies : spiral; globular clusters : general; infrared radiation; surveys ID H-I; MILKY-WAY; VELOCITY; SOUTHERN; CATALOG AB We present the basic properties of three objects near the Galactic Plane-a large galaxy and two candidate globular clusters-discovered in the Two Micron All-Sky Survey (2MASS) data set. All were noted during spot checks of the data during 2MASS quality assurance reviews. The galaxy is a late-type spiral galaxy (Sc-Sd), similar to 11 Mpc distant, at l = 236.degrees 82, b = - 1.degrees 86. From its observed angular extent of 6.'3 in the near infrared, we estimate an extinction-corrected optical diameter of similar to 9.'5, making it larger than most Messier galaxies. The candidate globular clusters are similar to 2'-3' in extent and are hidden optically behind foreground extinctions of A(V) similar to 18-21 mag at l similar to 10 degrees, b similar to 0 degrees. These chance discoveries were not the result of any kind of systematic search, but they do hint at the wealth of obscured sources of all kinds, many previously unknown, that are in the 2MASS data set. C1 CALTECH, Jet Prop Lab, Infrared Proc & Anal Ctr, Pasadena, CA 91125 USA. Univ Massachusetts, Astron Program, Amherst, MA 01003 USA. Observ Paris, United Sci Nancay, F-92195 Meudon, France. RP Hurt, RL (reprint author), CALTECH, Jet Prop Lab, Infrared Proc & Anal Ctr, MS 100-22, Pasadena, CA 91125 USA. NR 23 TC 45 Z9 46 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD OCT PY 2000 VL 120 IS 4 BP 1876 EP 1883 DI 10.1086/301549 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 364GQ UT WOS:000089884400023 ER PT J AU Schreiber, MR Gansicke, BT Cannizzo, JK AF Schreiber, MR Gansicke, BT Cannizzo, JK TI On the occurrence of dwarf nova outbursts in post novae SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE accretion, accretion disks; stars : binaries : close; stars : individual : V446 Her; stars : novae, cataclysmic variables ID IRRADIATED ACCRETION DISKS; LIMIT-CYCLE MECHANISM; CLASSICAL NOVAE; UV DELAY; CATACLYSMIC VARIABLES; GK-PERSEI; INSTABILITY; HIBERNATION; EVOLUTION; STARS AB We show that irradiation of the accretion disc by the white dwarf limits the occurrence of dwarf nova outbursts in post nova accretion discs. After the nova explosion, the white dwarf has to cool for up to similar to 100 yr - depending on the orbital period (i.e., disc size) and the temperature of the white dwarf after the nova-eruption - before the disc can begin producing dwarf nova outbursts. During this time the inner disc is maintained in a hot, ionised state. Using these calculations, we interpret the long-term photometric variability of the post nova V446 Her (Nova Her 1960) which shows today regular dwarf nova outbursts. As the white dwarf in V446 Her continues to cool over the next similar to 10-20 yr, we predict an increase in the amplitude of outbursts and a decrease of the outburst frequency, because the decreasing irradiation of the accretion disc should allow an increasing annular extent of the accretion disc to participate in limit cycle oscillations. C1 Univ Sternwarte, D-37083 Gottingen, Germany. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Schreiber, MR (reprint author), Univ Sternwarte, Geismarlandstr 11, D-37083 Gottingen, Germany. RI Gaensicke, Boris/A-9421-2012 OI Gaensicke, Boris/0000-0002-2761-3005 NR 42 TC 20 Z9 20 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 OCT PY 2000 VL 362 IS 1 BP 268 EP 272 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375CR UT WOS:000165382400026 ER PT J AU Nilsson, H Sikstrom, CM Li, ZS Lundberg, H Raassen, AJJ Johansson, S Leckrone, DS Svanberg, S AF Nilsson, H Sikstrom, CM Li, ZS Lundberg, H Raassen, AJJ Johansson, S Leckrone, DS Svanberg, S TI The FERRUM project: new experimental and theoretical f-values for 4p-4d transitions in FeII applied to HST spectra of chi Lupi SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE atomic data; line : identification; methods : laboratory; ultraviolet : stars; stars : individual : chi Lupi ID PROBABILITIES; LIFETIMES; STAR AB Radiative lifetimes for six highly excited levels in Fe II have been measured at Lund Laser Centre applying the laser induced fluorescence technique and two-step excitation. The energy levels belong to the even-parity 3d(6)(D-5)(4)d subconfiguration at about 10 eV. Branching fractions (BF:s) of 29 transitions from these levels to the 3d(6)(D-5)4p subconfiguration at about 5 eV have been measured in the wavelength region 2000-3000 Angstrom with the Lund Fourier Transform Spectrometer. By normalizing the BF:s with the lifetimes we get experimental oscillator strengths for these 29 4p-4d lines. The oscillator strengths are compared with new theoretical calculations using the orthogonal operator technique and applied to high-resolution spectra of the star chi Lupi, recorded with the Hubble Space Telescope. C1 Univ Lund, Dept Phys, S-22100 Lund, Sweden. Lund Inst Technol, Dept Phys, S-22100 Lund, Sweden. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. RP Nilsson, H (reprint author), Univ Lund, Dept Phys, POB 118, S-22100 Lund, Sweden. EM hampus.nilsson@fysik.lu.se OI Li, Zhongshan/0000-0002-0447-2748 NR 16 TC 12 Z9 12 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 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD OCT PY 2000 VL 362 IS 1 BP 410 EP 418 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375CR UT WOS:000165382400041 ER PT J AU Crawford, FL Keenan, FP Aggarwal, KM Wickstead, AW Aller, LH Feibelman, WA AF Crawford, FL Keenan, FP Aggarwal, KM Wickstead, AW Aller, LH Feibelman, WA TI Emission lines of OIII in the optical and ultraviolet spectra of planetary nebulae SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE atomic data; ISM : planetary nebulae : general ID FINE-STRUCTURE TRANSITIONS; O-III; ELECTRON TEMPERATURES; EXCITATION; STRENGTHS; RATIOS; IONS AB Recent R-matrix calculations of electron impact excitation rates in O III are used to calculate electron temperature and density-dependent emission line ratios R-1 = I(4363 Angstrom)/I(4960 Angstrom + 5007 Angstrom), R-2 = I(1661 Angstrom + 1667 Angstrom /I(4960 Angstrom + 5007 Angstrom) and R-3 = I(2322 Angstrom)/I(1661 Angstrom + 1667 Angstrom), for a range of electron temperatures (7500 less than or equal to T-e less than or equal to 30 000 K) and densities(10(4) less than or equal to N-e less than or equal to 10(7) cm(-3)) applicable to gaseous nebulae. The ratio-ratio diagrams(R-1, R-2) and (R-1, R-3) should, in principle, allow the simultaneous determination of T-e and N-e from measurements of the O III features in a spectrum. Plasma parameters derived for a sample of mid- to high-excitation planetary nebulae from (R-1, R-2) and (R-1, R-3) measurements, produced using a combination of ultraviolet spectra obtained with the international Ultraviolet Explorer (IUE) and optical data from a number of observing runs, are found to show excellent internal consistency. They also show, in general, good agreement with the values of T-e and N-e estimated from other line ratios in the nebulae, therefore providing observational support for the accuracy of the theoretical ratios and hence the atomic data adopted in their derivation. C1 Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. Queens Univ Belfast, Dept Pure Math, Belfast BT7 1NN, Antrim, North Ireland. Univ Calif Los Angeles, Los Angeles, CA 90024 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Crawford, FL (reprint author), Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. EM fergal.crawford@qub.ac.uk; f.keenan@qub.ac.uk; k.aggarwal@qub.ac.uk; a.wickstead@qub.ac.uk; aller@bonnie.astro.ucla.edu; feibelman@iue.gsfc.nasa.gov NR 44 TC 7 Z9 7 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 OCT PY 2000 VL 362 IS 2 BP 730 EP 736 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 376JU UT WOS:000165455100039 ER PT J AU Tegmark, M de Oliveira-Costa, A Staren, JW Meinhold, PR Lubin, PM Childers, JD Figueiredo, N Gaier, T Lim, MA Seiffert, MD Villela, T Wuensche, CA AF Tegmark, M de Oliveira-Costa, A Staren, JW Meinhold, PR Lubin, PM Childers, JD Figueiredo, N Gaier, T Lim, MA Seiffert, MD Villela, T Wuensche, CA TI Cosmic microwave background maps from the HACME experiment SO ASTROPHYSICAL JOURNAL LA English DT Article DE balloons; cosmic microwave background; cosmology : observations; On-line material : color figures ID WIENER RECONSTRUCTION; LOSING INFORMATION; RESOLUTION AB We present cosmic microwave background (CMB) maps from the Santa Barbara HACME balloon experiment (Staren et al.), covering about 1150 square degrees split between two regions in the northern sky, near the stars gamma Ursae Minoris and alpha Leonis, respectively. The FWHM of the beam is similar to 0.degrees 77 in three frequency bands centered on 39, 41, and 43 GHz. The results demonstrate that the thoroughly interconnected scan strategy employed allows efficient removal of 1/f-noise and slightly variable scan-synchronous offsets. The maps display no striping, and the noise correlations are found to be virtually isotropic, decaying on an angular scale similar to 1 degrees. The noise performance of the experiment resulted in an upper limit on CMB anisotropy. However, our results demonstrate that atmospheric contamination and other systematics resulting from the circular scanning strategy can be accurately controlled and bode well for the planned follow-up experiments BEAST and ACE, since they show that even with the overly cautious assumption that 1/f-noise and offsets will be as dominant as for HACME, the problems they pose can be readily overcome with the mapmaking algorithm discussed. Our prewhitened notch-filter algorithm for destriping and offset removal is proving useful also for other balloon- and ground-based experiments whose scan strategies involve substantial interleaving, e.g., Boomerang. C1 Univ Penn, Dept Phys, Philadelphia, PA 19104 USA. Inst Adv Study, Princeton, NJ 08540 USA. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. Escola Fed Engn Itajuba, BR-37500000 Itajuba, MG, Brazil. JPL, Pasadena, CA 91109 USA. Inst Space & Astronaut Sci, Kanagawa 229, Japan. Inst Nacl Pesquisas Espaciais, Div Astrofis, BR-12201970 Sao Jose Dos Campos, Brazil. RP Tegmark, M (reprint author), Univ Penn, Dept Phys, Philadelphia, PA 19104 USA. RI Figueiredo, Newton/F-9976-2011 NR 26 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2000 VL 541 IS 2 BP 535 EP 541 DI 10.1086/309442 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363FT UT WOS:000089825000003 ER PT J AU Markevitch, M Ponman, TJ Nulsen, PEJ Bautz, MW Burke, DJ David, LP Davis, D Donnelly, RH Forman, WR Jones, C Kaastra, J Kellogg, E Kim, DW Kolodziejczak, J Mazzotta, P Pagliaro, A Patel, S Van Speybroeck, L Vikhlinin, A Vrtilek, J Wise, M Zhao, P AF Markevitch, M Ponman, TJ Nulsen, PEJ Bautz, MW Burke, DJ David, LP Davis, D Donnelly, RH Forman, WR Jones, C Kaastra, J Kellogg, E Kim, DW Kolodziejczak, J Mazzotta, P Pagliaro, A Patel, S Van Speybroeck, L Vikhlinin, A Vrtilek, J Wise, M Zhao, P TI Chandra observation of abell 2142: Survival of dense subcluster cores in a merger SO ASTROPHYSICAL JOURNAL LA English DT Article DE cooling flows; galaxies : clusters : individual (Abell 2142); intergalactic medium; X-rays : general ID GALAXY CLUSTERS; COOLING FLOWS; EVOLUTION; SAMPLE; ROSAT AB We use Chandra data to map the gas temperature in the central region of the merging cluster A2142. The cluster is markedly nonisothermal; it appears that the central cooling flow has been disturbed but not destroyed by a merger. The X-ray image exhibits two sharp, bow-shaped, shocklike surface brightness edges or gas density discontinuities. However, temperature and pressure profiles across these edges indicate that these are not shock fronts. The pressure is reasonably continuous across these edges, while the entropy jumps in the opposite sense to that in a shock (i.e., the denser side of the edge has lower temperature, and hence lower entropy). Most plausibly, these edges delineate the dense subcluster cores that have survived a merger and ram pressure stripping by the surrounding shock-heated gas. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Birmingham, Birmingham B15 2TT, W Midlands, England. Univ Wollongong, Wollongong, NSW 2500, Australia. MIT, Cambridge, MA 02139 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. NASA, MSFC, Washington, DC 20546 USA. Univ Rome, Rome, Italy. Russian Acad Sci, Inst Space Res, Moscow 117901, Russia. RP Markevitch, M (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Mazzotta, Pasquale/B-1225-2016; OI Mazzotta, Pasquale/0000-0002-5411-1748; Forman, William/0000-0002-9478-1682 NR 18 TC 355 Z9 355 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2000 VL 541 IS 2 BP 542 EP 549 DI 10.1086/309470 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363FT UT WOS:000089825000004 ER PT J AU Valinia, A Arnaud, K Loewenstein, M Mushotzky, RF Kelley, R AF Valinia, A Arnaud, K Loewenstein, M Mushotzky, RF Kelley, R TI Hard X-ray observation of Abell 496 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cooling flows; galaxies : clusters : individual (Abell 496); intergalactic medium; X-rays : general ID EXTREME-ULTRAVIOLET EMISSION; TIMING EXPLORER; TEMPERATURE PROFILES; PERSEUS CLUSTER; COMA-CLUSTER; EMITTING GAS; COOLING FLOW; HIGH-ENERGY; GALAXIES; RADIATION AB We report the results of hard X-ray observations of Abell 496 (A496), a nearby relaxed cluster, using the Rossi X-Ray Timing Explorer (RXTE). The 3-20 keV spectrum of this cluster is well modeled by a thermal component of kT similar to 4.1 keV plus a cooling flow with mass accretion rate of (M) over dot similar to 285 M. yr(-1). The spectrum is equally well modeled by a multitemperature plasma component with a Gaussian temperature distribution of mean temperature 3.8 keV and sigma(kT) similar to 0.9 keV. The metallicity is found to be approximately 1/3 solar; however, the Ni/Fe ratio is about 3.6. No significant nonthermal emission at hard X-rays was detected for this cluster. We discuss the implications of the models presented here and compare them with the temperature profiles derived for this cluster using the Advanced Satellite for Cosmology and Astrophysics (ASCA). Our results are inconsistent with declining temperature profiles. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Valinia, A (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. RI Kelley, Richard/K-4474-2012 NR 37 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2000 VL 541 IS 2 BP 550 EP 555 DI 10.1086/309490 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363FT UT WOS:000089825000005 ER PT J AU Xu, C Gao, Y Mazzarella, J Lu, NY Sulentic, JW Domingue, DL AF Xu, C Gao, Y Mazzarella, J Lu, NY Sulentic, JW Domingue, DL TI Mapping infrared enhancements in closely interacting spiral-spiral pairs. I. ISO CAM and ISO SWS observations SO ASTROPHYSICAL JOURNAL LA English DT Review DE galaxies : interactions; galaxies : nuclei; galaxies : starburst; infrared : galaxies; stars : formation ID BRIGHT GALAXY SAMPLE; STAR-FORMATION RATES; ULTRALUMINOUS IRAS GALAXIES; MERGING DISK GALAXIES; HUBBLE DEEP FIELD; MOLECULAR GAS; COLLIDING GALAXIES; ANTENNAE GALAXIES; VIRGO CLUSTER; LUMINOSITY FUNCTIONS AB Mid-infrared (MIR) imaging and spectroscopic observations are presented for a well-defined sample of eight closely interacting (CLO) pairs of spiral galaxies that have overlapping disks and show enhanced far-infrared (FIR) emission. The goal is to study the star formation distribution in CLO pairs, with special emphasis on the role of "overlap starbursts." Observations were made with the Infrared Space Observatory (ISO) using the CAM and SWS instruments. The ISO CAM maps, tracing the MIR emission of warm dust heated by young massive stars, are compared to new ground-based Ha and R-band images. We identify three possible subgroups in the sample, classified according to the star formation morphology: (1) advanced mergers (Arp 157, Arp 244, and Arp 299), (2) severely disturbed systems (Asp 81 and Arp 278), and (3) less disturbed systems (Arp 276, KPG 347, and KPG 426). Localized starbursts are detected in the overlap regions in all five pairs of subgroups (1) and (2), suggesting that they are a common property in colliding systems. Except for Arp 244, the "overlap starburst" is usually fainter than the major nuclear starburst in CLO pairs. Star formation in "less disturbed systems" is often distributed throughout the disks of both galaxies with no "overlap starburst" detected in any of them. These systems also show less enhanced FIR emission, suggesting that they are in an earlier interaction stage when the direct disk collisions have probably not yet occurred. C1 CALTECH 10022, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. Max Planck Inst Kernphys, D-69117 Heidelberg, Germany. RP Xu, C (reprint author), CALTECH 10022, Jet Prop Lab, Ctr Infrared Proc & Anal, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 127 TC 31 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2000 VL 541 IS 2 BP 644 EP 659 DI 10.1086/309483 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363FT UT WOS:000089825000013 ER PT J AU Wojdowski, PS Clark, GW Kallman, TR AF Wojdowski, PS Clark, GW Kallman, TR TI An X-ray spectroscopic study of the SMC X-1/Sk 160 system SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : individual (SMC X-1); stars : winds, outflows; techniques : spectroscopic; X-rays : binaries ID RADIATION-DRIVEN WINDS; VELA X-1; CENTAURUS X-3; STELLAR WIND; HOT STARS; ECLIPSE; DYNAMICS; SPECTRUM; MODELS; BINARY AB We have investigated the composition and distribution of the wind of Sk 160, the supergiant companion of the X-ray star SMC X-l, by comparing an X-ray spectrum of the source, obtained with the ASCA observatory, during an eclipse with the computed spectra of reprocessed radiation from circumstellar matter with various density distributions. We show that the metal abundance in the wind of Sk 160 is no greater than a few tenths of solar, as has been determined for other objects in the Magellanic Clouds. We also show that the observed X-ray spectrum is not consistent with the density distributions of circumstellar matter of the spherically symmetric form derived for line-driven winds, nor with the density distribution derived from a hydrodynamic simulation of the X-ray perturbed and line-driven wind by Blondin & Woo. C1 MIT, Dept Phys, Cambridge, MA 02139 USA. MIT, Space Res Ctr, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wojdowski, PS (reprint author), Univ Calif Lawrence Livermore Natl Lab, POB 808, Livermore, CA 94551 USA. NR 35 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2000 VL 541 IS 2 BP 963 EP 976 DI 10.1086/309455 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363FT UT WOS:000089825000042 ER PT J AU Chaput, C Bloom, E Cominsky, L Godfrey, G Hertz, P Scargle, J Shabad, G Wen, H Wood, K Yentis, D AF Chaput, C Bloom, E Cominsky, L Godfrey, G Hertz, P Scargle, J Shabad, G Wen, H Wood, K Yentis, D TI A search for aperiodic millisecond variability in Cygnus X-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : individual (Cygnus X-1); stars : oscillations; X-rays : stars ID QUASI-PERIODIC OSCILLATIONS; RELATIVISTIC DISKOSEISMOLOGY; DRIPPING HANDRAIL; TRANSIENT CHAOS; POWER SPECTRA; BLACK-HOLES; RAY; MODEL AB We have conducted a search for aperiodic millisecond variability in the integrated 1-25 keV X-ray region of Cyg X-l. We have examined HEAO A-1 archival data and Rossi X-Ray Timing Explorer (RXTE) guest observer data for evidence of excess power above the Poisson noise floor using the relative integral power analysis and the Fourier transform method. Our results are in disagreement with the results of Meekins and coworkers. We attribute the discrepancy to an instrumental effect for which Meekins and coworkers did not apply a correction. With the correction we see no evidence for excess power above 25 Hz in the HEAO A-1 data. Our analysis of RXTE data is in agreement with previously published results of different data sets and shows no indication of excess power above 30 Hz. C1 Stanford Univ, Stanford Linear Accelerator Ctr, Stanford, CA 94309 USA. Sonoma State Univ, Rohnert Park, CA 94928 USA. USN, Res Lab, Washington, DC 20375 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Chaput, C (reprint author), Stanford Univ, Stanford Linear Accelerator Ctr, Stanford, CA 94309 USA. NR 30 TC 1 Z9 1 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2000 VL 541 IS 2 BP 1026 EP 1032 DI 10.1086/309444 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363FT UT WOS:000089825000046 ER PT J AU Birn, J Gosling, JT Hesse, M Forbes, TG Priest, ER AF Birn, J Gosling, JT Hesse, M Forbes, TG Priest, ER TI Simulations of three-dimensional reconnection in the solar corona SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; Sun : corona; Sun : flares; Sun : magnetic fields ID THIN CURRENT SHEETS; 3-DIMENSIONAL MAGNETIC RECONNECTION; X-RAY TELESCOPE; MASS EJECTIONS; MAGNETOTAIL DYNAMICS; MHD SIMULATIONS; HELMET STREAMER; PLASMA EJECTION; IMPULSIVE FLARE; FIELD AB Using ideal and resistive MHD, we investigate the stability and dynamic evolution of three-dimensional, magnetic field configurations, representing stretched arcade structures above a dipolar "photospheric" magnetic field. Two types of configurations are studied that differ by the amount of divergence ("fanning") of the initial held lines as viewed in the horizontal direction perpendicular to the photospheric magnetic neutral line and, correspondingly, by the radial decrease of magnetic field strength and current density. The two sets of configurations are found to differ in their stability behavior. The strongly fanning fields, associated with a rapid radial decrease of the field strength, current density, and plasma pressure, are more stable. A stability difference is found also when the configurations are first subjected to a converging motion of photospheric footpoints toward the neutral line, which leads to the buildup of thin current sheets in the region above. This current sheet formation is more pronounced for the weakly fanning fields. For similar current density enhancements, the occurrence of anomalous dissipation (resistivity) initiates magnetic reconnection in either configuration. However, the effects are much more drastic in magnitude and spread in the weakly diverging field structure. In the unstable cases, a strongly localized electric field parallel to the magnetic field develops, which results in integrated voltages with maximum values of the order of a few hundred MeV, both on open and closed field lines. For comparison, we studied both low-beta, force-free, and high-beta initial states. The weakly fanning high-beta configurations tend to show more drastic instability effects than the corresponding low-beta fields, but the stabilization of the strongly fanning fields pertains to both low-beta and high-beta fields. The three-dimensional reconnection in the unstable cases generates a region of intertwined magnetic flux tubes with different topologies that lie below a region of closed flux ropes not affected by reconnection. The topological changes could be the source of open flux tubes that are occasionally observed within coronel mass ejections, as recently discussed by Gosling et al. The fast outward flow generated in these simulations affects only the regions of changing topology but does not cause the above-lying closed flux ropes to move (within the times considered). This may be seen as an indication that reconnection may be associated with the onset of a flare, initiated after the eruption of a coronal mass ejection, but is not the driver of the coronal mass ejection itself. C1 Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ New Hampshire, Durham, NH 03824 USA. Univ St Andrews, St Andrews KY16 9SS, Fife, Scotland. RP Los Alamos Natl Lab, MS D466, Los Alamos, NM 87545 USA. EM jbirn@lanl.gov; hesse@gsfc.nasa.gov; terry.forbes@unh.edu; eric@dcs.st-and.ac.uk RI Hesse, Michael/D-2031-2012 NR 67 TC 30 Z9 30 U1 1 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 1 PY 2000 VL 541 IS 2 BP 1078 EP 1095 DI 10.1086/309452 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363FT UT WOS:000089825000050 ER PT J AU Brown, JC Karlicky, M Mandzhavidze, N Ramaty, R AF Brown, JC Karlicky, M Mandzhavidze, N Ramaty, R TI Hard X-rays from neutralized ion beams in solar flares SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : flares; Sun : particle emission; Sun : X-rays, gamma rays ID ABUNDANCES; ELECTRONS; PROTONS; SPECTROSCOPY AB Under suitable conditions, hard X-rays (HXRs) may be emitted by a neutralized proton beam due to the "heating" of the electrostatically dragged electrons in collisions with a nearly neutral background atmosphere. A simple estimate is made generalizing this HXR emission mechanism to heavier ions dragging a neutralizing electron current. Recent gamma-ray results on the energy content of flare ions of greater than or equal to 1 MeV nucleon(-1) are used to estimate the total HXR yield above 20 keV or so which would be expected from these processes, and in 19 flares the results are compared with HXR data in the same events. It is Found that only in two flares are the neutral beam HXRs clearly important and that in a few others they may be significant. In most events, however, the neutral beam HXR contribution is small, though the ion energy is comparable with that of electrons. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Astron Inst, Ondrejov 25165, Czech Republic. RP Brown, JC (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Univ Space Res Assoc, Code 661, Greenbelt, MD 20771 USA. RI Karlicky, Marian/G-9023-2014 NR 20 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2000 VL 541 IS 2 BP 1104 EP 1108 DI 10.1086/309481 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363FT UT WOS:000089825000052 ER PT J AU Canuto, VM AF Canuto, VM TI The physics of subgrid scales in numerical simulations of stellar convection: Are they dissipative, advective, or diffusive? SO ASTROPHYSICAL JOURNAL LA English DT Article DE convection; stars : evolution; stars : interiors ID COMPRESSIBLE CONVECTION; TURBULENCE; ROTATION; STARS; SUN AB All numerical simulations of stellar convection assume that the unresolved subgrid scales (SGSs) are only dissipative. We show that the assumption is incorrect and that the SGSs stir (advection), mix (diffusion), and dissipate. The first two processes were never considered before. We also show that there are two advective velocities: one contributed by the resolved scales and the other, a bolus velocity, by the unresolved scales. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Appl Phys, New York, NY 10027 USA. RP Canuto, VM (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 12 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD OCT 1 PY 2000 VL 541 IS 2 BP L79 EP L82 DI 10.1086/312895 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363FX UT WOS:000089825400012 ER PT J AU Cowings, PS Toscano, WB DeRoshia, C Miller, NE AF Cowings, PS Toscano, WB DeRoshia, C Miller, NE TI Promethazine as a motion sickness treatment: Impact on human performance and mood states SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE antimotion sickness medication; rotating chairs; human performance; mood states; sleep ID ALCOHOL; DEFICITS; FLIGHT; SYSTEM; TESTS AB Purpose: Intramuscular (i.m.) injections of promethazine in 25 mg or 50 mg dosages are commonly used to treat space motion sickness in astronauts. The present study examined the effects of i.m. injections of promethazine on performance, mood states, and motion sickness in humans. Methods: Subjects were 12 men, mean age 36 +/- 3.1, who participated in 1 training day and 3 treatment conditions: a 25-mg injection of promethazine, a 50-mg injection of promethazine, and a placebo injection of sterile saline. Each condition, scheduled at 7-d intervals, required an 8-10-h day in which subjects were tested on 12 performance tasks, and were given a rotating chair motion sickness test. On the training day subjects were trained on each task to establish stability and proficiency. Treatment conditions were counterbalanced and a double-blind procedure was used to administer the medication or placebo. Results: Statistically significant decrements in performance were observed for both dosages of promethazine as compared with the placebo. Performance decrements were associated with mean blood alcohol dose equivalency levels of 0.085% for 25 mg and 0.137% for 50 mg doses. Mood scale results showed significant changes in individual subjective experiences with maximum deterioration in the arousal state and fatigue level. Only the 25-mg dosage significantly increased motion sickness tolerance when compared with the placebo. Conclusions These data suggest that effective doses of promethazine currently used to counteract motion sickness in astronauts may significantly impair task components of their operational performance. C1 NASA, Div Life Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Cowings, PS (reprint author), NASA, Div Life Sci, Ames Res Ctr, Mail Stop 239-16, Moffett Field, CA 94035 USA. NR 36 TC 16 Z9 18 U1 0 U2 3 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 OCT PY 2000 VL 71 IS 10 BP 1013 EP 1022 PG 10 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 356ZA UT WOS:000089473000005 PM 11051308 ER PT J AU Callini, G Essig, SM Heher, DM Young, LR AF Callini, G Essig, SM Heher, DM Young, LR TI Effectiveness of an expert system for astronaut assistance on a sleep experiment SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE expert system; sleep; space; artificial intelligence AB Background: Principal Investigator-in-a-Box ([PI]) is an expert system designed to train and assist astronauts with the performance of an experiment outside their field of expertise, particularly when contact with the Principal investigators on the ground is limited or impossible, in the current case, [PI] was designed to assist with the calibration and troubleshooting procedures of the Neurolab Sleep and Respiration Experiment. [PI] displays physiological signals in real time during the pre-sleep instrumentation period, alerts the astronauts when a poor signal quality is detected, and displays steps to improve quality. Methods: Two studies are presented in this paper. In the first study 12 subjects monitored a set of prerecorded physiological signals and attempted to identify any signal artifacts appearing on the computer screen. Every subject performed the experiment twice, once with the,assistance of [PI] and once without. The second part of this study focuses on the postflight analysis of the data gathered from the Neurolab Mission. After replaying the physiological signals on the ground, the frequency of correct [PI] alerts and false alarms (i.e., incorrect diagnoses by the expert system) was determined in order to assess the robustness and accuracy of the rules. Conclusions: Results the ground study indicated a beneficial effect of [PI] and training in reducing anomaly detection time and the number of undetected anomalies. For the in-flight performance, excluding the saturated signals, the expert system had an 84% detection accuracy, and the questionnaires filled out by the astronauts showed positive crew reactions to the expert system. C1 MIT, Man Vehicle Lab, Cambridge, MA 02139 USA. NASA, Caelum Res Corp, Ames Res Ctr, Moffett Field, CA USA. RP Young, LR (reprint author), MIT, Man Vehicle Lab, 77 Massachusetts Ave,Room 37-219, Cambridge, MA 02139 USA. NR 8 TC 5 Z9 6 U1 0 U2 2 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 OCT PY 2000 VL 71 IS 10 BP 1023 EP 1032 PG 10 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 356ZA UT WOS:000089473000006 PM 11051309 ER PT J AU Kuriyama, K Ueno, T Ballard, RE Cowings, PS Toscano, WB Watenpaugh, DE Hargens, AR AF Kuriyama, K Ueno, T Ballard, RE Cowings, PS Toscano, WB Watenpaugh, DE Hargens, AR TI Cerebrovascular responses during lower body negative pressure-induced presyncope SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE orthostatic tolerance; human; cerebral blood flow velocity; cerebral tissue oxygenation; lower body negative pressure; fainting ID CEREBRAL HEMODYNAMICS; ORTHOSTATIC STRESS; BLOOD-PRESSURE; AUTOREGULATION; FLOW AB Background: Reduced orthostatic tolerance is commonly observed after spaceflight, occasionally causing presyncopal symptoms which may be due to low cerebral blood flow (CBF). It has been suggested that CBF decreases in early stages of exposure to orthostatic stress. The purpose of this study was to investigate cerebrovascular responses during presyncope induced by lower body negative pressure (LBNP). Hypothesis: Although CBF decreases during LBNP exposure, blood pressure (BP) or heart rate (HR) contributes more to induce presyncopal conditions. Methods: Eight healthy male volunteers were exposed to LBNP in steps of 10 mm Hg every 3 min until presyncopal symptoms were detected. Electrocardiogram (ECG) was monitored continuously and arterial BP was measured by arterial tonometry. CBF velocity at the middle cerebral artery was measured by transcranial Doppler sonography (TCD). Cerebral tissue oxygenation was detected using near-infrared spectroscopy (NIRS). We focused our investigation on the data obtained during the final 2 min before the presyncopal endpoint. Results: BP gradually decreased from 2 min to 10 s before the endpoint and fell more rapidly during the final 10 s. HR did not change significantly during presyncope. CBF velocity did not change significantly, while cerebral tissue oxygenation decreased prior to the presyncopal endpoint in concert with BP. Our results suggest that CBF is maintained in the middle cerebral artery during presyncope, while BP decreases rapidly. Conclusions: Cerebrovascular hemodynamics are relatively well maintained while arterial hypotension occurs just prior to syncope. C1 Univ Tokyo, Fac Med, Sch Hlth Sci & Nursing, Dept Hlth Adm,Bunkyo Ku, Tokyo 113, Japan. NASA, Gravitat Res Branch, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Hargens, AR (reprint author), Univ Calif San Diego, Dept Orthopaed, 350 Dickinson St,8894, San Diego, CA 92103 USA. NR 20 TC 10 Z9 10 U1 0 U2 4 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 OCT PY 2000 VL 71 IS 10 BP 1033 EP 1038 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 356ZA UT WOS:000089473000007 PM 11051310 ER PT J AU Scarpa, PJ AF Scarpa, PJ TI President's message SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article C1 NASA, Kennedy Space Ctr, FL 32899 USA. RP Scarpa, PJ (reprint author), NASA, Mail Code TA-C2, Kennedy Space Ctr, FL 32899 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 OCT PY 2000 VL 71 IS 10 BP 1075 EP 1076 PG 2 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 356ZA UT WOS:000089473000014 ER PT J AU Sibonga, JD Zhang, M Evans, GL Westerlind, KC Cavolina, JM Morey-Holton, E Turner, RT AF Sibonga, JD Zhang, M Evans, GL Westerlind, KC Cavolina, JM Morey-Holton, E Turner, RT TI Effects of spaceflight and simulated weightlessness on longitudinal bone growth SO BONE LA English DT Article DE rat bone elongation; skeletal unloading; hind-limb elevation; unilateral sciatic neurotomy; growth plate; spaceflight ID MESSENGER-RNA LEVELS; CANCELLOUS BONE; GROWING RATS; OVARIECTOMIZED RATS; MATRIX PROTEINS; SPACE-FLIGHT; LONG-BONES; HISTOMORPHOMETRY; IMMOBILIZATION; PLATES AB Indirect measurements have suggested that spaceflight impairs bone elongation in rats. To test this possibility, our laboratory measured, by the fluorochrome labeling technique, bone elongation that occurred during a spaceflight experiment. The longitudinal growth rate (LGR) in the tibia of rats in spaceflight experiments (Physiological Space Experiments 1, 3, and 4 and Physiological-Anatomical Rodent Experiment 3) and in two models of skeletal unloading (hind-limb elevation and unilateral sciatic neurotomy) were calculated. The effects of an 11 day spaceflight on gene expression of cartilage matrix proteins in rat growth plates were also determined by northern analysis and are reported for the first time in this study. Measurements of longitudinal growth indicate that skeletal unloading generally did not affect LGR, regardless of age, strain, gender, duration of unloading, or method of unloading. There was, however, one exception with 34% suppression in LGR detected in slow-growing, ovariectomized rats skeletally unloaded for 8 days by hind-limb elevation. This detection of reduced LGR by hind-limb elevation is consistent with changes in steady-state mRNA levels for type II collagen (-33%) and for aggrecan (-53%) that were detected in rats unloaded by an 11 day spaceflight, The changes detected in gene expression raise concern that spaceflight may result in changes in the composition of extracellular matrix, which could have a negative impact on conversion of growth-plate cartilage into normal cancellous bone by endochondral ossification. (Bone 27: 535-640; 2000) (C) 2000 by Elsevier Science Inc. All rights reserved. C1 Mayo Clin, Dept Orthoped, Rochester, MN USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Sibonga, JD (reprint author), Mayo Clin, Dept Orthoped Res, MSB 3-69,200 1st St SW, Rochester, MN 55905 USA. NR 30 TC 34 Z9 37 U1 0 U2 6 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 8756-3282 J9 BONE JI Bone PD OCT PY 2000 VL 27 IS 4 BP 535 EP 540 DI 10.1016/S8756-3282(00)00352-5 PG 6 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 363XG UT WOS:000089862500010 PM 11033449 ER PT J AU Cohen, SC AF Cohen, SC TI Viscoelastic postseismic rebound from strike-slip earthquakes in regions of oblique plate convergence SO BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA LA English DT Article ID NEW-ZEALAND; DEFORMATION; ADJACENT; ISLAND; ALASKA; JAPAN AB According to the slip-partitioning concept, the trench parallel component of relative plate motion in regions of oblique convergence is accommodated by strike-slip faulting in the overriding continental lithosphere. The pattern of postseismic surface deformation due to viscoelastic flow in the lower crust and asthenosphere following a major earthquake on such a fault is modified from that predicted from the conventional elastic layer over viscoelastic half-space model by the presence of the subducting slab. The predicted effects, such as a partial suppression of the postseismic velocities by 1 cm/yr or more immediately following a moderate to great earthquake, are potentially detectable using contemporary geodetic techniques. C1 NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. RP Cohen, SC (reprint author), NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. NR 19 TC 2 Z9 2 U1 0 U2 0 PU SEISMOLOGICAL SOC AMER PI EL CERRITO PA PLAZA PROFESSIONAL BLDG, SUITE 201, EL CERRITO, CA 94530 USA SN 0037-1106 J9 B SEISMOL SOC AM JI Bull. Seismol. Soc. Amer. PD OCT PY 2000 VL 90 IS 5 BP 1318 EP 1322 DI 10.1785/0119990136 PG 5 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 372TR UT WOS:000165250600015 ER PT J AU Thedinga, JF Wertheimer, AC Heintz, RA Maselko, JM Rice, SD AF Thedinga, JF Wertheimer, AC Heintz, RA Maselko, JM Rice, SD TI Effects of stock, coded-wire tagging, and transplant on straying of pink salmon (Oncorhynchus gorbuscha) in southeastern Alaska SO CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES LA English DT Article ID POPULATIONS; TSHAWYTSCHA; HATCHERY AB Straying of pink salmon (Oncorhynchus gorbuscha) from two wild stocks (intertidal and upstream) in southeastern Alaska was estimated. Secondary factors (coded-wire tagging and transplanting of the intertidal stock) that may influence straying were also evaluated. In 1996, 321 494 fry were marked with either coded-wire tags or pelvic-fin clips. A total of 3828 marked adults were recovered in their natal streams and 79 strays were recovered in streams within 60 km of the release sites. The overall estimated straying rate was 5.1%. Estimated straying for the intertidal stock (9.2%) was higher than straying of the upstream stock (3.7%) but was not statistically different due to high variance of the estimates. The proportion of fish straying was significantly greater (P = 0.01) for coded-wire-tagged than for pelvic-fin-clipped fish for the upstream but not for the transplanted stock. Straying and distribution of the transplanted stock were more similar to those of the upstream stock, which was endemic to the natal watershed and release site of the transplant, than to those of the intertidal stock, which was the donor stock for the transplant. Although tagging may influence straying, incubation and initial estuarine environment appear to be major determinants of the natural straying of pink salmon in southeastern Alaska. C1 Natl Marine Fisheries Serv, NOAA, Alaska Fisheries Sci Ctr, Auke Bay Fisheries Lab, Juneau, AK 99801 USA. RP Thedinga, JF (reprint author), Natl Marine Fisheries Serv, NOAA, Alaska Fisheries Sci Ctr, Auke Bay Fisheries Lab, 11305 Glacier Hwy, Juneau, AK 99801 USA. EM john.thedinga@noaa.gov RI Piper, Walter/B-7908-2009 NR 35 TC 21 Z9 23 U1 0 U2 2 PU CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS PI OTTAWA PA 1200 MONTREAL ROAD, BUILDING M-55, OTTAWA, ON K1A 0R6, CANADA SN 0706-652X J9 CAN J FISH AQUAT SCI JI Can. J. Fish. Aquat. Sci. PD OCT PY 2000 VL 57 IS 10 BP 2076 EP 2085 DI 10.1139/cjfas-57-10-2076 PG 10 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 371PX UT WOS:000165188300012 ER PT J AU Nahra, HK Kamotani, Y AF Nahra, HK Kamotani, Y TI Bubble formation from wall orifice in liquid cross-flow under low gravity SO CHEMICAL ENGINEERING SCIENCE LA English DT Article DE bubble generation; gas-liquid flow; liquid cross-flow; microgravity; scaling; forces ID REDUCED GRAVITY AB Two-phase flows present a wide variety of applications for spacecraft thermal control systems design. Bubble formation and detachment is an integral part of the two-phase flow science. The objective of the present work is to experimentally investigate the effects of liquid cross-ow velocity, gas flow rate, and orifice diameter on bubble formation in a wall-bubble injection configuration. Data were taken mainly under reduced gravity conditions but some data were taken in normal gravity for comparison. The reduced gravity experiment was conducted aboard the NASA DC-9 Reduced Gravity Aircraft. The results show that the process of bubble formation and detachment depends on gravity, the orifice diameter, the gas flow rate, and the liquid cross-flow velocity. The data are analyzed based on a force balance, and two different detachment mechanisms are identified. When the gas momentum is large, the bubble detaches from the injection orifice as the gas momentum overcomes the attaching effects of liquid drag and inertia. The surface tension force is much reduced because a large part of the bubble pinning edge at the orifice is lost as the bubble axis is tilted by the liquid flow. When the gas momentum is small, the force balance in the Liquid flow direction is important, and the bubble detaches when the bubble axis inclination exceeds a certain angle. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, John H Glenn Res Ctr, Micrograv Fluid Phys Branch, Micrograv Sci Div, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Aerosp & Mech Engn, Cleveland, OH 44106 USA. RP Nahra, HK (reprint author), NASA, John H Glenn Res Ctr, Micrograv Fluid Phys Branch, Micrograv Sci Div, 21000 Brookpk Rd,MS-500-102, Cleveland, OH 44135 USA. NR 17 TC 28 Z9 32 U1 0 U2 6 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0009-2509 J9 CHEM ENG SCI JI Chem. Eng. Sci. PD OCT PY 2000 VL 55 IS 20 BP 4653 EP 4665 DI 10.1016/S0009-2509(00)00102-0 PG 13 WC Engineering, Chemical SC Engineering GA 354MM UT WOS:000089334300021 ER PT J AU Covey, C Abe-Ouchi, A Boer, GJ Boville, BA Cubasch, U Fairhead, L Flato, GM Gordon, H Guilyardi, E Jiang, X Johns, TC Le Treut, H Madec, G Meehl, GA Miller, R Noda, A Power, SB Roeckner, E Russell, G Schneider, EK Stouffer, RJ Terray, L von Storch, JS AF Covey, C Abe-Ouchi, A Boer, GJ Boville, BA Cubasch, U Fairhead, L Flato, GM Gordon, H Guilyardi, E Jiang, X Johns, TC Le Treut, H Madec, G Meehl, GA Miller, R Noda, A Power, SB Roeckner, E Russell, G Schneider, EK Stouffer, RJ Terray, L von Storch, JS TI The seasonal cycle in coupled ocean-atmosphere general circulation models SO CLIMATE DYNAMICS LA English DT Article ID SURFACE AIR-TEMPERATURE; SPATIAL VARIABILITY; CLIMATE SENSITIVITY; CO2; INCREASE; PROJECT; LAYER AB We examine the seasonal cycle of near-surface air temperature simulated by 17 coupled ocean-atmosphere general circulation models participating in the Coupled Model Intercomparison Project (CMIP). Nine of the models use ad hoc "flux adjustment" at the ocean surface to bring model simulations close to observations of the present-day climate. We group flux-adjusted and non-flux-adjusted models separately and examine the behaviol- of each class. When averaged over all of the flux-adjusted model simulations, near-surface air temperature falls within 2 K of observed values over the oceans. The corresponding average over non-flux-adjusted models shows errors up to similar to6 K in extensive ocean areas. Flux adjustments are not directly applied over land, and near-surface land temperature errors are substantial in the average over flux-adjusted models, which systematically underestimates (by similar to5 K) temperature in areas of elevated terrain. The corresponding average over non-flux-adjusted models forms a similar error pattern (with somewhat increased amplitude) over land. We use the temperature difference between July and January to measure seasonal cycle amplitude. Zonal means of this quantity from the individual flux-adjusted models form a fairly tight cluster (all within similar to 30% of the mean) centered on the observed values. The nonflux-adjusted models perform nearly as well at most latitudes. In Southern Ocean mid-latitudes, however, the non-flux-adjusted models overestimate the magnitude of January-minus-July temperature differences by similar to5 K due to an overestimate of summer (January) near-surface temperature. This error is common to five of the eight non-flux-adjusted models. Also, over Northern Hemisphere mid-latitude land areas, zonal mean differences between July and January temperatures simulated by the non-flux-adjusted models show a greater spread (positive and negative) about observed values than results from the flux-adjusted models. Elsewhere, differences between the two classes of models are less obvious. At no latitude is the zonal mean difference between averages over the two classes of models greater than the standard deviation over models. The ability of coupled GCMs to simulate a reasonable seasonal cycle is a necessary condition for confidence in their prediction of long-term climatic changes (such as global warming), but it is not a sufficient condition unless the seasonal cycle and long-term changes involve similar climatic processes. To test this possible connection, we compare seasonal cycle amplitude with equilibrium warming under doubled atmospheric carbon dioxide for the models in our data base. A small but positive correlation exists between these two quantities. This result is predicted by a simple conceptual model of the climate system, and it is consistent with other modeling experience, which indicates that the seasonal cycle depends only weakly on climate sensitivity. C1 Univ Calif Lawrence Livermore Natl Lab, Program Climate Model Diag & Intercomparison, Livermore, CA 94550 USA. Ctr Climate Syst Res, Tokyo 153, Japan. Canadian Ctr Climate Modeling & Anal, Victoria, BC V8W 2Y2, Canada. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. German Climate Comp Ctr, D-20146 Hamburg, Germany. Max Planck Inst Meteorol, D-20146 Hamburg, Germany. CNRS, Meteorol Dynam Lab, F-75252 Paris 05, France. CSIRO, Div Atmospher Res, Mordialloc, Vic 3195, Australia. CERFACS, Climate Modeling & Global Change Team, F-31057 Toulouse, France. Goddard Inst Space Studies, New York, NY 10025 USA. UK Meteorol Off, Hadley Ctr, Bracknell RG12 2SY, Berks, England. Lab Dynam Oceanog & Climatol, F-75252 Paris 05, France. Meteorol Res Inst, Tsukuba, Ibaraki 305, Japan. Bur Meteorol Res Ctr, Melbourne, Vic 3001, Australia. Ctr Ocean Land Atmosphere Studies, Calverton, MD 20705 USA. Geophys Fluid Dynam Lab, Princeton, NJ 08542 USA. Univ Hamburg, Inst Meteorol, D-20146 Hamburg, Germany. RP Covey, C (reprint author), Univ Calif Lawrence Livermore Natl Lab, Program Climate Model Diag & Intercomparison, Mail Code L-264, Livermore, CA 94550 USA. RI madec, gurvan/E-7825-2010; Guilyardi, Eric/D-4868-2011; Abe-Ouchi, Ayako/M-6359-2013; Flato, Gregory/K-6711-2015; Terray, Laurent/B-8056-2008 OI madec, gurvan/0000-0002-6447-4198; Guilyardi, Eric/0000-0002-2255-8625; Abe-Ouchi, Ayako/0000-0003-1745-5952; Terray, Laurent/0000-0001-5512-7074 NR 33 TC 32 Z9 35 U1 1 U2 8 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0930-7575 J9 CLIM DYNAM JI Clim. Dyn. PD OCT PY 2000 VL 16 IS 10-11 BP 775 EP 787 DI 10.1007/s003820000081 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 368LD UT WOS:000090117700004 ER PT J AU Russell, GL Gornitz, V Miller, JR AF Russell, GL Gornitz, V Miller, JR TI Regional sea level changes projected by the NASA/GISS Atmosphere-Ocean Model SO CLIMATE DYNAMICS LA English DT Article ID CLIMATE-CHANGE; RISE AB Sea level has been rising for the past century, and coastal residents of the Earth will want to understand and predict future sea level changes. In this study we present sea level changes from new simulations of the Goddard Institute for Space Studies (GISS) global atmosphere-ocean model fi om 1950 to 2099. The free surface, mass conserving ocean model leads to a straightforward calculation of these changes. Using observed levels of greenhouse gases between 1950 and 1990 and a compounded 0.5% annual increase in CO2 after 1990, model projections show that global sea level measured from 1950 will rise by 61 mm in the year 2000, by 212 mm in 2050, and by 408 mm in 2089. By 2089, 64% of the global sea level rise will be due to thermal expansion and 36% will be due to ocean mass changes. The Arctic Ocean will show a greater than average sea level rise, while the Antarctic circumpolar region will show a smaller rise in agreement with other models. Model results are also compared with observed sea level changes during the past 40 years at 12 coastal stations around the world. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Russell, GL (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 29 TC 24 Z9 24 U1 0 U2 7 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0930-7575 J9 CLIM DYNAM JI Clim. Dyn. PD OCT PY 2000 VL 16 IS 10-11 BP 789 EP 797 DI 10.1007/s003820000090 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 368LD UT WOS:000090117700005 ER PT J AU Aminzadeh, F Barhen, J Glover, CW Toomarian, NB AF Aminzadeh, F Barhen, J Glover, CW Toomarian, NB TI Reservoir parameter estimation using a hybrid neural network SO COMPUTERS & GEOSCIENCES LA English DT Article DE neural networks; oil exploration; reservoir characterization; seismic attributes AB The accuracy of an artificial neural network (ANN) algorithm is a crucial issue in the estimation of an oil field's reservoir properties from the log and seismic data. This paper demonstrates the use of the k-fold cross validation technique to obtain confidence bounds on an ANN's accuracy statistic from a finite sample set. In addition, we also show that an ANN's classification accuracy is dramatically improved by transforming the ANN's input feature space to a dimensionally smaller, new input space. The new input space represents a feature space that maximizes the linear separation between classes. Thus, the ANN's convergence time and accuracy are improved because the ANN must merely find nonlinear perturbations to the starting linear decision boundaries. These techniques for estimating ANN accuracy bounds and feature space transformations are demonstrated on the problem of estimating the sand thickness in an oil field reservoir based only on remotely sensed seismic data. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 dGB USA & FACT Inc, Sugarland, TX 77478 USA. Oak Ridge Natl Lab, Ctr Engn Syst Adv Res, Oak Ridge, TN USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Aminzadeh, F (reprint author), dGB USA & FACT Inc, 14019 SW Freeway,Suite 301-230, Sugarland, TX 77478 USA. NR 10 TC 17 Z9 19 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0098-3004 J9 COMPUT GEOSCI-UK JI Comput. Geosci. PD OCT PY 2000 VL 26 IS 8 BP 869 EP 875 DI 10.1016/S0098-3004(00)00027-3 PG 7 WC Computer Science, Interdisciplinary Applications; Geosciences, Multidisciplinary SC Computer Science; Geology GA 346HM UT WOS:000088865000002 ER PT J AU Xiao, YC Ziebarth, JP AF Xiao, YC Ziebarth, JP TI FEM-based scattered data modeling and visualization SO COMPUTERS & GRAPHICS-UK LA English DT Article DE scattered data; modeling; visualization; finite element method; interpolation ID INTERPOLATION AB A critical challenge in visualizing scattered data is to correctly model the sample data so that data variation throughout the volume of interest call be accurately rendered. The commonly used interpolation-based approach is unsatisfactory, as it often generates physically impossible data values in the modeling process. In addition, it does not provide a systematic way of estimating errors. The interpolation methods used for modeling are usually different from those used for rendering, which causes inconsistency and misrepresentation. Furthermore, interpolation methods cannot handle discontinuities, due to their inherent assumption that the data are continuous. To eliminate these and other problems, we construct an alternative approach to scattered data visualization. Based on the finite element method (FEM), this FEM-based approach incorporates the governing equations of the da ta into the modeling process to ensure the modeled data to be physically meaningful. It provides error estimates that can guide the refinement of the finite element network to obtain the desired accuracy. It allows the selection of basis functions in the modeling process to march with the interpolation functions used by the rendering process so that consistency can be achieved. It handles discontinuities with the help of the double-layer scheme. Furthermore, it converts the data-modeling problem from an interpolation problem into a boundary-value problem, and therefore reduces the requirement on the density of the input sample data, a feature which is very valuable to applications where sample data a re hard to obtain. This paper presents the Framework and a sample implementation of the FEM-based approach along with some examples. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Akron, Dept Math & Comp Sci, Akron, OH 44325 USA. NASA, Ames Res Ctr, Numer Aerosp Simulat Div, Moffett Field, CA 94035 USA. RP Xiao, YC (reprint author), Univ Akron, Dept Math & Comp Sci, Ayer Hall 235, Akron, OH 44325 USA. NR 33 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0097-8493 J9 COMPUT GRAPH-UK JI Comput. Graph.-UK PD OCT PY 2000 VL 24 IS 5 BP 775 EP 789 DI 10.1016/S0097-8493(00)00078-9 PG 15 WC Computer Science, Software Engineering SC Computer Science GA 372VR UT WOS:000165255200011 ER PT J AU Kirkham, H AF Kirkham, H TI IMD versus THD SO ELECTRONICS WORLD LA English DT Letter C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Kirkham, H (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU REED BUSINESS INFORMATION LTD PI SUTTON PA QUADRANT HOUSE THE QUADRANT, SUTTON SM2 5AS, SURREY, ENGLAND SN 0959-8332 J9 ELECTRON WORLD JI Electron. World PD OCT PY 2000 VL 106 IS 1774 BP 827 EP 827 PG 1 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 354WW UT WOS:000089354700042 ER PT J AU Panontin, TL Makino, A Williams, JF AF Panontin, TL Makino, A Williams, JF TI Crack tip opening displacement estimation formulae for C(T) specimens SO ENGINEERING FRACTURE MECHANICS LA English DT Article DE crack tip opening displacement; J-integral; m-factor; eta-factor; compact tension testing; finite element analysis ID BEND SPECIMENS; SINGLE AB Improved formulae for estimating crack tip opening displacement (CTOD) from test records of compact tension (C(T)) specimens are developed. Two-dimensional, plane strain, finite element analyses of 1T C(T) specimens are made for normalized crack depths, a/W, of 0.40-0.70 using Ramberg-Osgood material behavior with strain hardening coefficients n = 5, 10, and 20. Finite element predictions of J, CTOD, crack mouth opening displacement (CMOD) and load are used to obtain proportionality constants relating the area under the load-CMODpl curve to J(pl), and J to CTOD in terms of a/W and n. Improvements in CTOD estimates of 25% over existing estimation methods are obtained. Correction factors for displacements measured on the specimen front face instead of the load line are also examined. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Mat & Failure Anal Grp, Moffett Field, CA 94035 USA. RP Panontin, TL (reprint author), NASA, Ames Res Ctr, Mat & Failure Anal Grp, MS 213-4, Moffett Field, CA 94035 USA. NR 9 TC 14 Z9 15 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0013-7944 J9 ENG FRACT MECH JI Eng. Fract. Mech. PD OCT PY 2000 VL 67 IS 3 BP 293 EP 301 DI 10.1016/S0013-7944(00)00048-5 PG 9 WC Mechanics SC Mechanics GA 356GW UT WOS:000089436400007 ER PT J AU Sogard, SM Olla, BL AF Sogard, SM Olla, BL TI Effects of group membership and size distribution within a group on growth rates of juvenile sablefish Anoplopoma fimbria SO ENVIRONMENTAL BIOLOGY OF FISHES LA English DT Article DE fish behavior; schooling; size disparity; density; growth; food availability ID SALVELINUS-ALPINUS L; ARCTIC CHARR; GASTEROSTEUS-ACULEATUS; SOCIAL CONSTRAINTS; ONCORHYNCHUS-KETA; FOOD DISTRIBUTION; ATLANTIC SALMON; RAINBOW-TROUT; CHUM SALMON; CANNIBALISM AB Group membership can confer both advantages and disadvantages to growth in juvenile fishes. The balance between costs and benefits of social interactions can shift depending on such factors as the composition of the group (density and size disparity) and the availability of food. We examined the effect of these factors on absolute growth and growth depensation in juvenile sablefish, Anoplopoma fimbria. Increasing density and increasing size disparity had little influence on absolute growth rates of juvenile sablefish and the effects of these social factors were not modified by ration level. In experiments testing density effects, absolute growth did not differ among groups of 1, 3, or 10 fish held at high rations, but at low rations single fish exhibited a different pattern of size-dependent growth compared to fish in groups. In experiments testing disparity effects, absolute growth did not differ between groups with an even size distribution and groups with a mixed size distribution. The relative size of an individual within a group, i.e., small, medium, or large, also did not modify growth, despite evidence of higher chasing behavior in mixed size distributions. Although the growth of small fish was not diminished in the presence of large fish, negative impacts of size disparity were expressed in high levels of cannibalism, which occurred in 42% of groups with a mixed size distribution. Significant growth depensation over time occurred in the density experiment, but not in the size disparity experiment, possibly due to the shorter duration of the latter experiment. We suggest that growth depensation was generated by individual variability in growth capacity rather than social effects on growth rates. Schooling behavior, measured by group cohesion indices, increased with fish size and was higher in groups with an even vs. a mixed size distribution. These results for sablefish are consistent with other schooling species in which growth variability is determined by exploitative competition and/or genetic variability in growth capacity rather than interference competition. C1 Hatfield Marine Sci Ctr, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Newport, OR 97365 USA. RP Sogard, SM (reprint author), Hatfield Marine Sci Ctr, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Newport, OR 97365 USA. NR 54 TC 13 Z9 15 U1 4 U2 10 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0378-1909 J9 ENVIRON BIOL FISH JI Environ. Biol. Fishes PD OCT PY 2000 VL 59 IS 2 BP 199 EP 209 DI 10.1023/A:1007659903444 PG 11 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 351DR UT WOS:000089143000008 ER PT J AU Brodziak, J Mikus, R AF Brodziak, J Mikus, R TI Variation in life history parameters of Dover sole, Microstomus pacificus, off the coasts of Washington, Oregon, and northern California SO FISHERY BULLETIN LA English DT Article ID FLATFISHES; PATTERNS; MATURITY; CLIMATE; FISHES; GROWTH AB Variation in the life history parameters of Dover sole (Microstomus pacificus) off the coasts of Washington, Oregon, and northern California was investigated by using research survey data. We compared growth, maturation, and length-weight curves of Dover sole within the International North Pacific Fisheries Commission (INPFC) statistical areas of Monterey, Eureka, Columbia, and Vancouver. We found strong evidence of dimorphism in growth and maturation rates between sexes. In addition, geographic variation in both growth and maturation rates was also suggested. Male and female Dover sole from the Columbia area had lower Brody growth coefficients and larger asymptotic lengths than Dover sole from other areas. Further; there was an apparent latitudinal dine in maturation rates because males and females matured at smaller size and younger ages at higher latitudes. In contrast, no difference between male and female length-weight relationships was detected. In comparison with other pleuronectids, we found that Dover sole matured at relatively larger sizes and younger ages. These differences likely reflect adaptation of Dover sole to the inherent variability of the California Current. C1 NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Hatfield Marine Sci Ctr, Newport, OR 97365 USA. Hatfield Marine Sci Ctr, Oregon Dept Fish & Wildlife, Newport, OR 97365 USA. RP Brodziak, J (reprint author), NW Fisheries Sci Ctr, 166 Water St, Woods Hole, MA 02543 USA. NR 40 TC 14 Z9 15 U1 0 U2 1 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 USA SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD OCT PY 2000 VL 98 IS 4 BP 661 EP 673 PG 13 WC Fisheries SC Fisheries GA 381EV UT WOS:000165750100001 ER PT J AU Gledhill, CT Lyczkowski-Shultz, J AF Gledhill, CT Lyczkowski-Shultz, J TI Indices of larval king mackerel (Scomberomorus cavalla) abundance in the Gulf of Mexico for use in population assessments SO FISHERY BULLETIN LA English DT Article ID OF-MEXICO; FISHERIES MANAGEMENT; UNITED-STATES; NORTH-SEA; FISH; GROWTH; VARIABILITY; JUVENILES; FECUNDITY; AGE AB The stock status of the Gulf of Mexico migratory group of king mackerel (Scomberomorus cavalla) is currently evaluated by using age-based sequential virtual population analysis (VPA). We examined king mackerel larval occurrence and abundance indices from annual ichthyoplankton surveys, developed an age-adjusted abundance index, and questioned whether larval indices of abundance are useful for calibrating the king mackerel VPA. Gulf of Mexico king mackerel larval occurrence and abundance increased over a fourteen-year time series from 1982 to 1995 and were highly correlated with spawning stock size. Correlations between stock size and larval occurrence, and between stock size and larval abundance,were 0.82 and 0.84, respectively. The correlation between larval occurrence and stock size for the years 1986-35 increased to 0.91, owing to the addition in 1986 of a fall survey with added coverage during peak spawning. Daily instantaneous mortality rate (Z) was estimated by regression of larval catch curves. Although a large amount of interannual variability in mortality rates was noted, no statistical differences were detected among years. The instantaneous daily mortality rate estimated by pooling all years, Z = 0.53, was used to develop an age-adjusted index for king mackerel in order to eliminate the influence of variable larval age composition among years. This adjusted index did not improve correlations between stock size and larval abundance (r=0.78). For now, indices of larval occurrence and unadjusted larval abundance from ichthyoplankton collections reflect trends in spawning stock size and provide useful variables for calibrating the king mackerel VPA. C1 NOAA, Natl Marine Fisheries Serv, SE Fisheries Sci Ctr, Pascagoula, MS 39568 USA. RP Gledhill, CT (reprint author), NOAA, Natl Marine Fisheries Serv, SE Fisheries Sci Ctr, 3209 Frederic St, Pascagoula, MS 39568 USA. NR 32 TC 9 Z9 10 U1 1 U2 8 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 USA SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD OCT PY 2000 VL 98 IS 4 BP 684 EP 691 PG 8 WC Fisheries SC Fisheries GA 381EV UT WOS:000165750100003 ER PT J AU Ignell, S Haynes, E AF Ignell, S Haynes, E TI Geographic patterns in growth of the giant Pacific sea scallop, Patinopecten caurinus SO FISHERY BULLETIN LA English DT Article C1 NOAA, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, Juneau, AK 99801 USA. RP Ignell, S (reprint author), NOAA, Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Auke Bay Lab, 11305 Glacier Highway, Juneau, AK 99801 USA. NR 29 TC 6 Z9 6 U1 0 U2 0 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 USA SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD OCT PY 2000 VL 98 IS 4 BP 849 EP 853 PG 5 WC Fisheries SC Fisheries GA 381EV UT WOS:000165750100018 ER PT J AU Johnson, DL AF Johnson, DL TI Preliminary examination of the match-mismatch hypothesis and recruitment variability of yellowtail flounder, Limanda ferruginea SO FISHERY BULLETIN LA English DT Article ID FISH C1 NOAA, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, James J Howard Marine Sci Lab Sandy Hook, Highlands, NJ 07732 USA. RP Johnson, DL (reprint author), NOAA, Natl Marine Fisheries Serv, NE Fisheries Sci Ctr, James J Howard Marine Sci Lab Sandy Hook, 74 Magruder Rd, Highlands, NJ 07732 USA. NR 18 TC 6 Z9 6 U1 1 U2 2 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 USA SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD OCT PY 2000 VL 98 IS 4 BP 854 EP 863 PG 10 WC Fisheries SC Fisheries GA 381EV UT WOS:000165750100019 ER PT J AU Kvenberg, J Stolfa, P Stringfellow, D Garrett, ES AF Kvenberg, J Stolfa, P Stringfellow, D Garrett, ES TI HACCP development and regulatory assessment in the United States of America SO FOOD CONTROL LA English DT Article DE HACCP; food safety; critical control points; critical limits; pathogen reduction; regulatory; risk; verification; validation AB Hazard Analysis Critical Control Point (HACCP) is internationally recognized as the best method of assuring product safety by controlling foodborne safety hazards. Currently, within the USA, the FDA has mandated HACCP for fish and fishery products and is proposing mandating HACCP for fruit and vegetable juices. The USDA has mandated Pathogen Reduction/HACCP requirements for meat and poultry processing, and the NMFS Seafood Inspection Program operates a voluntary HACCP program for seafood plants. The requirements for mandatory implementation and proposed regulations represent a significant change in the manner in which foods are regulated for food safety and necessitate a new understanding of the different roles and responsibilities between the food industries and the regulatory agencies within the USA. Each agency will approach the evaluation process differently given their unique legislative authorities and programmatic operations. Nevertheless, each agency agrees that HACCP is the best food control system of choice and is committed to improve food safety requirements. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. C1 US FDA, Div HACCP Programs, HFS 615, Washington, DC 20204 USA. USDA, FSIS, Washington, DC 20250 USA. Natl Marine Fisheries Serv, Natl Seafood Inspect Lab, Pascagoula, MS 39568 USA. RP Kvenberg, J (reprint author), US FDA, Div HACCP Programs, HFS 615, 200 St SW, Washington, DC 20204 USA. NR 30 TC 15 Z9 18 U1 1 U2 11 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0956-7135 J9 FOOD CONTROL JI Food Control PD OCT PY 2000 VL 11 IS 5 BP 387 EP 401 DI 10.1016/S0956-7135(99)00090-0 PG 15 WC Food Science & Technology SC Food Science & Technology GA 314BL UT WOS:000087034200010 ER PT J AU Visscher, PT Reid, RP Bebout, BM AF Visscher, PT Reid, RP Bebout, BM TI Microscale observations of sulfate reduction: Correlation of microbial activity with lithified micritic laminae in modern marine stromatolites SO GEOLOGY LA English DT Article DE stromatolites; calcium carbonate precipitation; sulfate reduction; bacteria ID SOLAR LAKE SINAI; CYANOBACTERIAL MATS; STOCKING-ISLAND; EXUMA-CAYS; BAHAMAS; SULFUR; CALCIFICATION; CARBONATES; SEDIMENTS; OXIDATION AB We report for the first time micrometer-scale correlation of geologic and microbial processes in modern marine stromatolites. Precipitation of micritic laminae in these stromatolites was studied by comparing microstructure, as observed in petrographic thin sections, with microbial sulfate-reduction activity. Two-dimensional mapping of sulfate-reduction rates was implemented by incubating a vertical section of a stromatolite face on silver foil coated with (SO42-)-S-35. Our results show that sulfate-reduction activity is high in zones of CaCO3 precipitation and indicate that microbial activity produces lithified micritic laminae near the surface of the stromatolites. Similarities with micritic laminae in ancient stromatolites suggest that sulfate reduction may also have been an important mechanism of carbonate precipitation in these fossilized structures. C1 Univ Connecticut, Dept Marine Sci, Groton, CT 06340 USA. Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Miami, FL 33149 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Univ Connecticut, Dept Marine Sci, Groton, CT 06340 USA. EM pieter.visscher@uconn.edu OI Visscher, Pieter/0000-0001-6911-1532 NR 40 TC 211 Z9 224 U1 3 U2 25 PU GEOLOGICAL SOC AMER, INC PI BOULDER PA PO BOX 9140, BOULDER, CO 80301-9140 USA SN 0091-7613 EI 1943-2682 J9 GEOLOGY JI Geology PD OCT PY 2000 VL 28 IS 10 BP 919 EP 922 DI 10.1130/0091-7613(2000)028<0919:MOOSRC>2.3.CO;2 PG 4 WC Geology SC Geology GA 364KV UT WOS:000089892300014 ER PT J AU Douglas, S Douglas, DD AF Douglas, S Douglas, DD TI Environmental scanning electron microscopy studies of colloidal sulfur deposition in a natural microbial community from a cold sulfide spring near Ancaster, Ontario, Canada SO GEOMICROBIOLOGY JOURNAL LA English DT Article DE colloidal sulfur; ESEM; microbial community ID SPINAE; CHLOROBIUM; BACTERIA AB We have used a relatively new microscopical technique, environmental scanning electron microscopy (ESEM), along with transmission electron microscopy (TEM) and light microscopy, to investigate a unique microbial community from a temperate-climate, cold sulfide spring near Ancaster, Ontario, Canada. ESEM allows the viewing of fully hydrated specimens that have not undergone the structural or chemical alterations imposed by the extensive procedures necessary for viewing biological specimens in a vacuum. Besides allowing visualization of microorganisms in their natural form and as intact assemblages, ESEM also detects elements, especially those higher than Si, which tend to be lost or masked by the processes used to prepare samples for conventional SEM and for TEM thin sections. In this study we report new information about the structure of bacteriogenic sulfur deposits and their relationship to the structural aspects of a natural microbial community from a cold sulfide spring. C1 NASA, Jet Prop Lab, Pasadena, CA 91009 USA. Univ Guelph, Dept Microbiol, Guelph, ON N1G 2W1, Canada. RP Douglas, S (reprint author), NASA, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91009 USA. NR 20 TC 12 Z9 12 U1 3 U2 6 PU TAYLOR & FRANCIS INC PI PHILADELPHIA PA 325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA SN 0149-0451 J9 GEOMICROBIOL J JI Geomicrobiol. J. PD OCT-DEC PY 2000 VL 17 IS 4 BP 275 EP 289 DI 10.1080/01490450050192974 PG 15 WC Environmental Sciences; Geosciences, Multidisciplinary SC Environmental Sciences & Ecology; Geology GA 388MM UT WOS:000166184900002 ER PT J AU Sabutis, JL Manney, GL AF Sabutis, JL Manney, GL TI Wave propagation in the 1999-2000 Arctic early winter stratosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NORTHERN-HEMISPHERE AB Stratospheric wave propagation during the unusually cold NH early winter 99-00 is studied and compared to the recent cold winters of 94-95, 95-96 (the previous coldest NH winter) and 96-97. EP fluxes reveal less wave activity entered the stratosphere in 95-96 and 99-00, substantial temperature decreases during long periods of little wave activity in 94-95 and 99-00, and little wave propagation into the upper stratosphere in Nov 99-Jan 00 and Nov 95-mid-Jan 96. 2-D and 3-D EP fluxes for 95-96 and 99-00 show both that wave activity was inhibited from propagating upward and poleward through the middle stratosphere until mid-Jan, and there was large horizontal propagation of wave activity in the middle and lower stratosphere during Nov and Dec. Thus, both less wave activity entering the stratosphere, and a background structure that prevented wave activity from propagating into the upper stratosphere, were important factors in producing unusually cold early winters in 95-96 and 99-00. C1 New Mexico Highlands Univ, Dept Phys, Las Vegas, NV USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Sabutis, JL (reprint author), New Mexico Highlands Univ, Dept Phys, Las Vegas, NV USA. EM jsabutis@physics.nmhu.edu; manney@mls.jpl.nasa.gov NR 12 TC 8 Z9 8 U1 0 U2 0 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 OCT 1 PY 2000 VL 27 IS 19 BP 3205 EP 3208 DI 10.1029/2000GL011767 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 361FG UT WOS:000089711900045 ER PT J AU Santee, ML Manney, GL Livesey, NJ Waters, JW AF Santee, ML Manney, GL Livesey, NJ Waters, JW TI UARS Microwave Limb Sounder observations of denitrification and ozone loss in the 2000 Arctic late winter SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID POLAR VORTEX; LOWER STRATOSPHERE; MLS OBSERVATIONS; HNO3 AB The UARS Microwave Limb Sounder obtained measurements of CIO, HNO3, and O-3 inside the Arctic lower stratospheric vortex during two intervals in February and March 2000. The data show evidence of significant chemical processing in February, consistent with the exceptionally cold conditions that prevailed earlier in the winter. Ozone at 465 K decreased by 0.04 +/- 0.01 ppmv/day in early February, implying chemical loss rates greater than those observed during the 1995-1996 winter, which was also unusually cold in the lower stratosphere. A persistent depression in the HNO3 abundances in late March, well after polar stratospheric cloud activity had ceased, suggests a moderate degree (similar to 20%) of denitrification around the 465 K level at 70 degrees N and higher equivalent latitudes. This is the strongest evidence yet seen for the occurrence of denitrification in the Arctic over spatial scales large enough to be detected in satellite measurements. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Santee, ML (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 183-701, Pasadena, CA 91109 USA. NR 11 TC 53 Z9 53 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 OCT 1 PY 2000 VL 27 IS 19 BP 3213 EP 3216 DI 10.1029/2000GL011738 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 361FG UT WOS:000089711900047 ER PT J AU Han, QY Rossow, WB Chou, J Welch, RM AF Han, QY Rossow, WB Chou, J Welch, RM TI Near-global survey of cloud column susceptibilities using ISCCP data SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DROPLET CONCENTRATION; ALBEDO; LAYER; MODEL AB A new parameter, cloud column susceptibility, is introduced to study the aerosol indirect effect, which describes the aerosol indirect effect more directly without assuming how cloud droplet size will respond to changes of droplet number concentration. Between the two approaches that used to retrieve cloud column susceptibilities, the one that makes no assumption of constant liquid water content leads to smaller, even negative cloud column susceptibilities. This finding is consistent with results of model studies and observations from the 1998-1999 Indian Ocean Experiment (INDOEX) that suggest that cloud liquid water content may be reduced during aerosol-cloud interactions. The results of this survey suggest that using constant liquid water content in models may lead to significant overestimation of the aerosol indirect effect. C1 Univ Alabama, Dept Atmospher Sci, Natl Space Sci & Technol Ctr, Huntsville, AL 35805 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Han, QY (reprint author), Univ Alabama, Dept Atmospher Sci, Natl Space Sci & Technol Ctr, 320 Sparkman Dr, Huntsville, AL 35805 USA. RI Rossow, William/F-3138-2015 NR 17 TC 8 Z9 8 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 1 PY 2000 VL 27 IS 19 BP 3221 EP 3224 DI 10.1029/2000GL011543 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 361FG UT WOS:000089711900049 ER PT J AU Li, JH Dijkstra, P Hymus, GJ Wheeler, RM Piastuch, WC Hinkle, CR Drake, BG AF Li, JH Dijkstra, P Hymus, GJ Wheeler, RM Piastuch, WC Hinkle, CR Drake, BG TI Leaf senescence of Quercus myrtifolia as affected by long-term CO2 enrichment in its native environment SO GLOBAL CHANGE BIOLOGY LA English DT Article DE carbon dioxide; chlorophyll; leaf senescence; nitrogen; Rubisco ID ELEVATED CARBON-DIOXIDE; PLANT SENESCENCE; ESTUARINE MARSH; GAS-EXCHANGE; NITROGEN; GROWTH; LEAVES; ACCLIMATION; RESPONSES; WHEAT AB The long-term effects of elevated (ambient plus 350 mu mol mol(-1)) atmospheric CO2 concentration (C-a) on the leaf senescence of Quercus myrtifolia Willd was studied in a scrub-oak community during the transition from autumn (December 1997) to spring (April 1998). Plants were grown in large open-top chambers at the Smithsonian CO2 Research Site, Merritt Island Wildlife Refuge, Cape Canaveral, Florida. Chlorophyll (a + b) concentration, Rubisco activity and N concentration decreased by 75%, 82%, and 52%, respectively, from December (1997) to April (1998) in the leaves grown at ambient C-a. In contrast, the leaves of plants grown at elevated C-a showed no significant decrease in chlorophyll (a + b) concentration or Rubisco activity, and only a 25% reduction in nitrogen. These results indicate that leaf senescence was delayed during this period at elevated C-a. Delayed leaf senescence in elevated C-a had important consequences for leaf photosynthesis. In elevated C-a the net photosynthetic rate of leaves that flushed in Spring 1997 (last year's leaves) and were 13 months old was not different from fully-expanded leaves that flushed in 1998, and were approximately 1 month old (current year's leaves). In ambient C-a the net photosynthetic rate of last year's leaves was 54% lower than for current year's leaves. When leaves were fully senesced, nitrogen concentration decreased to about 40% of the concentration in non-senesced leaves, in both CO2 treatments. In April, net photosynthesis was 97% greater in leaves grown in elevated C-a than in those grown at ambient. During the period when elevated C-a delayed leaf senescence, more leaves operating at higher photosynthetic rate would allow the ecosystem dominated by Q. myrtifolia to gain more carbon at elevated C-a than at ambient C-a. C1 Smithsonian Environm Res Ctr, Edgewater, MD 21037 USA. Natl Res Council, Kennedy Space Ctr, FL 32899 USA. NASA, Biomed Off, Kennedy Space Ctr, FL 32899 USA. Dynamac Corp, Kennedy Space Ctr, FL 32899 USA. RP Drake, BG (reprint author), Smithsonian Environm Res Ctr, POB 28, Edgewater, MD 21037 USA. NR 32 TC 22 Z9 23 U1 0 U2 4 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 1354-1013 J9 GLOB CHANGE BIOL JI Glob. Change Biol. PD OCT PY 2000 VL 6 IS 7 BP 727 EP 733 DI 10.1046/j.1365-2486.2000.00347.x PG 7 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 365CR UT WOS:000089931300002 ER PT J AU White, A Cannell, MGR Friend, AD AF White, A Cannell, MGR Friend, AD TI CO2 stabilization, climate change and the terrestrial carbon sink SO GLOBAL CHANGE BIOLOGY LA English DT Article DE carbon; climate change; CO2; ecosystem; sink; tropical forest ID NET PRIMARY PRODUCTION; ATMOSPHERIC CO2; BIOSPHERE-MODEL; STOMATAL CONDUCTANCE; BIOGEOCHEMICAL MODEL; FOREST ECOSYSTEMS; TROPICAL FORESTS; GLOBAL CHANGE; N-DEPOSITION; NITROGEN AB A nonequilibrium, dynamic, global vegetation model, Hybrid v4.1, with a subdaily timestep, was driven by increasing CO2 and transient climate output from the UK Hadley Centre GCM (HadCM2) with simulated daily and interannual variability. Three IPCC emission scenarios were used: (i) IS92a, giving 790 ppm CO2 by 2100, (ii) CO2 stabilization at 750 ppm by 2225, and (iii) CO2 stabilization at 550 ppm by 2150. Land use and future N deposition were not included. In the IS92a scenario, boreal and tropical lands warmed 4.5 degrees C by 2100 with rainfall decreased in parts of the tropics, where temperatures increased over 6 degrees C in some years and vapour pressure deficits (VPD) doubled. Stabilization at 750 ppm CO2 delayed these changes by about 100 years while stabilization at 550 ppm limited the rise in global land surface temperature to 2.5 degrees C and lessened the appearance of relatively hot, dry areas in the tropics. Present-day global predictions were 645 PgC in vegetation, 1190 PgC in soils, a mean carbon residence time of 40 years, NPP 47 PgC y(-1) and NEP (the terrestrial sink) about 1 PgC y(-1), distributed at both high and tropical latitudes. With IS92a emissions, the high latitude sink increased to the year 2100, as forest NPP accelerated and forest vegetation carbon stocks increased. The tropics became a source of CO2 as forest dieback occurred in relatively hot, dry areas in 2060-2080. High VPDs and temperatures reduced NPP in tropical forests, primarily by reducing stomatal conductance and increasing maintenance respiration. Global NEP peaked at 3-4 PgC y(-1) in 2020-2050 and then decreased abruptly to near zero by 2100 as the tropical source offset the high-latitude sink. The pattern of change in NEP was similar with CO2 stabilization at 750 ppm, but was delayed by about 100 years and with a less abrupt collapse in global NEP. CO2 stabilization at 550 ppm prevented sustained tropical forest dieback and enabled recovery to occur in favourable years, while maintaining a similar time course of global NEP as occurred with 750 ppm stabilization. By lessening dieback, stabilization increased the fraction of carbon emissions taken up by the land. Comparable studies and other evidence are discussed: climate-induced tropical forest dieback is considered a plausible risk of following an unmitigated emissions scenario. C1 Inst Terr Ecol, Penicuik EH26 0QB, Midlothian, Scotland. Rutgers State Univ, Ctr Environm Predict, New Brunswick, NJ 08901 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP White, A (reprint author), Heriot Watt Univ, Dept Math, Edinburgh EH14 4AS, Midlothian, Scotland. RI El Husny, Chafic/G-5410-2012 NR 86 TC 43 Z9 50 U1 6 U2 35 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 1354-1013 J9 GLOB CHANGE BIOL JI Glob. Change Biol. PD OCT PY 2000 VL 6 IS 7 BP 817 EP 833 DI 10.1046/j.1365-2486.2000.00358.x PG 17 WC Biodiversity Conservation; Ecology; Environmental Sciences SC Biodiversity & Conservation; Environmental Sciences & Ecology GA 365CR UT WOS:000089931300009 ER PT J AU Starr, R Clark, PE Murphy, ME Floyd, SR McClanahan, TP Nittler, LR Trombka, JI Evans, LG Boynton, WV Bailey, SH Bhangoo, J Mikheeva, I Bruckner, J Squyres, SW McCartney, EM Goldsten, JO McNutt, RL AF Starr, R Clark, PE Murphy, ME Floyd, SR McClanahan, TP Nittler, LR Trombka, JI Evans, LG Boynton, WV Bailey, SH Bhangoo, J Mikheeva, I Bruckner, J Squyres, SW McCartney, EM Goldsten, JO McNutt, RL TI Instrument calibrations and data analysis procedures for the NEAR X-ray spectrometer SO ICARUS LA English DT Article DE asteroids; instrumentation; X-rays; NEAR ID ASTEROID RENDEZVOUS MISSION AB The X-Ray spectrometer onboard the Near Earth Asteroid Rendezvous spacecraft will measure X-rays from the surface of 433 Eros in the energy region 0.7-10 keV, Detection of characteristic K alpha line emissions from Mg, Al, Si, Ca, Ti, and Fe will allow the determination of surface abundances of these geologically important elements, Spatial resolution as fine as 3 km will be possible for those elements where counting statistics are not a limiting factor, These measurements will make it possible to relate Eros to known classes of meteorites and reveal geological processes that occurred on Eros. The calibration measurements and analysis procedures presented here are necessary for the reduction and analysis of the X-ray data to be collected during one year of orbital operations at Eros, (C) 2000 Academic Press. C1 Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Comp Sci Corp, Sci Programs, Laurel, MD 20707 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Max Planck Inst Chem, D-55128 Mainz, Germany. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. RP Starr, R (reprint author), Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. EM richard.starr@gsfc.nasa.gov RI McNutt, Ralph/E-8006-2010 OI McNutt, Ralph/0000-0002-4722-9166 NR 17 TC 19 Z9 19 U1 0 U2 1 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 OCT PY 2000 VL 147 IS 2 BP 498 EP 519 DI 10.1006/icar.2000.6453 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 368NY UT WOS:000090125100013 ER PT J AU Shepard, MK Benner, LAM Ostro, SJ Harris, AW Rosema, KD Shapiro, II Chandler, JF Campbell, DB AF Shepard, MK Benner, LAM Ostro, SJ Harris, AW Rosema, KD Shapiro, II Chandler, JF Campbell, DB TI Radar observations of Asteroid 2100 Ra-Shalom SO ICARUS LA English DT Article DE asteroids; radar; surfaces, asteroids; asteroids, composition; asteroids, Ra-Shalom ID NEAR-EARTH ASTEROIDS; VENUS; ARECIBO AB We report Doppler-only (cw) radar observations of near-Earth Asteroid 2100 Ra-Shalom obtained at the Arecibo Observatory using a transmitter frequency of 2380 MHz (12.6 cm) on 1984 Aug. 18-22. Weighted and filtered sums of cw echoes achieve a maximum signal-to-noise ratio of 74 and cover the asteroid in rotation phase. A weighted sum of all cw spectra gives an opposite circular (OC) radar cross section of 1.13 +/- 0.40 km(2) and a circular polarization ratio of 0.31 +/- 0.02. Inversion of echo edge frequencies yields a convex hull with an elongation (maximum breadth/minimum breadth) of 1.15 +/- 0.03 and places a lower bound on the maximum pole-on dimension of 2.4 km/cos delta, where delta is the angle between the radar line-of-sight and the asteroid's apparent equator. Ra-Shalom has one of the least elongated pole-on silhouettes of the near-Earth asteroids for which similar shape information from radar observations is available. Ra-Shalom's effective diameter (diameter of a sphere with equal cross-sectional area) is constrained to a range of 2.4-3.6 km. We use a two-component radar scattering model to remove the "diffuse" contributions from Ra-Shalom's radar cross section and obtain a surface bulk density estimate of 1.1-3.3 g cm(-3). When compared with reported bulk densities and porosities of meteorites, our results are consistent with either: (1) a C-class asteroid with carbonaceous-chondritic composition, effective diameter 2.6-3.6 km, and surface porosity <70%; or (2) an S-class asteroid with ordinary-chondritic or stony-iron composition, effective diameter 2.4-2.6 km, and little or no surface regolith. Ra-Shalom's near-surface roughness appears to be globally heterogeneous. (C) 2000 Academic Press. C1 Bloomsburg Univ Penn, Dept Geog & Geosci, Bloomsburg, PA 17815 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Cornell Univ, Natl Astron & Ionosphere Ctr, Ithaca, NY 14853 USA. RP Shepard, MK (reprint author), Bloomsburg Univ Penn, Dept Geog & Geosci, Bloomsburg, PA 17815 USA. NR 29 TC 7 Z9 7 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 2000 VL 147 IS 2 BP 520 EP 529 DI 10.1006/icar.2000.6470 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 368NY UT WOS:000090125100014 ER PT J AU Nelson, RM Hapke, BW Smythe, WD Spilker, LJ AF Nelson, RM Hapke, BW Smythe, WD Spilker, LJ TI The opposition effect in simulated planetary regoliths. Reflectance and circular polarization ratio change at small phase angle SO ICARUS LA English DT Article ID COHERENT BACKSCATTER; SATELLITES; LIGHT AB We measured the change in reflectance and in circular polarization ratio with respect to phase angle of a suite of well-sorted, highly reflective, aluminum oxide powders for the purpose of understanding the contribution of the coherent backscattering phenomenon to the reflectance phase curves of planetary regoliths. The goniometric photopolarimeter that we used measured reflectance and circular polarization ratio over the range of phase angles from 0.05 degrees to 5 degrees where it has been suggested that coherent backscattering becomes important. The particle size of the samples varied from 0.1 to 30 mum, The wavelength of the illuminating radiation from a HeNe laser was 0.633 mum. We find that the reflectance at 0.05 degrees is weakly dependent on particle size. We measured to good approximation the half-width half-maximum (HWHM) of the phase curves, and we find that there is only a weak qualitative agreement between our experimental results and the theoretical estimates of the HWHM for particles of comparable index of refraction and packing density as predicted by M. Mishchenko (1992, Astrophys. Space Sci, 194, 327-333), For particle sizes that are close to the wavelength of the illuminating radiation we find that Mishchenko's model overestimates the HWHM of the phase curve by an order of magnitude. For particle sizes that are much larger or much smaller than the wavelength of the incident radiation the theoretical model underestimates the HWHM of the phase curve by more than an order of magnitude for the smallest particle sizes and factors of several for the large particle sizes. This disagreement between our experimental data and the predictions from theoretical modeling is not unexpected given the assumptions made in the theoretical models that the particles scatter light like isolated, perfect uniform spheres and that the variation in particle size distribution used by Mishchenko was remarkably small, smaller than that of the well-sieved particle sizes used in our experiment. For all samples the circular polarization ratio increased with decreasing phase angle consistent with the hypothesis that the coherent backscattering process is the principal contributor to the reflectance phase curve near 0 degrees for highly reflective, multiply scattering, particulate media. We confirm our previously reported significant opposition surges for powders with sizes 50 times larger and 6 times smaller than the wavelength of the incident light (R. Nelson et al. 1998, Proc. Lurar Planet. Sci, Conf, 29th, Abstract 1146). This suggests that for cases where the wavelength of the incident radiation is much larger than the candidate regolith particle size, the photons behave as if they were interacting with ensembles of particles of size comparable to the wavelength of the incident radiation, For cases where the particle size is much larger than the wavelength of the incident light, the photons appear to be interacting primarily with wavelength-sized cracks, surface asperities, or other irregularities in the regolith particles rather than with the particle as a whole. This work, using sorted powders as planetary surface regolith analogues, has applicability for remote sensing studies of highly reflective planetary regoliths such as might be expected to be found on many the icy satellites of the outer Solar System, Many of these bodies exhibit sharp opposition surges that are most likely due to coherent backscattering, (C) 2000 Academic Press. C1 Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. Univ Pittsburgh, Dept Geol & Planetary Sci, Pittsburgh, PA 15250 USA. RP Nelson, RM (reprint author), Jet Prop Lab, Div Earth & Space Sci, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 32 TC 69 Z9 69 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 2000 VL 147 IS 2 BP 545 EP 558 DI 10.1006/icar.2000.6454 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 368NY UT WOS:000090125100016 ER PT J AU Horz, F Zolensky, ME Bernhard, RP See, TH Warren, JL AF Horz, F Zolensky, ME Bernhard, RP See, TH Warren, JL TI Impact features and projectile residues in aerogel exposed on Mir SO ICARUS LA English DT Article DE collisional physics; cratering; impact processes; interplanetary dust; meteorites ID INTERPLANETARY DUST; SILICA AEROGEL; METAL TARGETS; CAPTURE; PARTICLES; CRATERS; INTACT AB Approximately 0.63 m(2) of SiO2-based aerogel (0.02 g cm(-3)) was exposed for 18 months on the Mir Station to capture hypervelocity particles from both man-made and natural sources. Optical inspection revealed two major classes of hypervelocity impact features in the aerogel: (1) long, carrot-shaped tracks, well known from laboratory impact experiments, that exhibit a depth- (t) to-diameter (D) relationship of t/D > 10, typically 20-30, and (2) shallow pits (t/D < 10; typically 1-3) that have no laboratory analog. Blunt-nosed, yet deep (t/D = 5-10), cylindrically shaped cavities suggest the existence of transitional morphologies between these tracks and pits. All tracks contain projectile residues that are unmelted, while pits rarely contain even traces of projectile material. These and other observations suggest that slender tracks form at lower impact velocities than the shallow pits. In addition, we observed that the measured track-length does not systematically correlate with the size of the projectile residue. This renders the reconstruction of encounter velocity and/or projectile mass from measured track dimensions not feasible at present. Recovery of particles from individual tracks is time-consuming, yet readily accomplished by operators familiar with the handling of individual, micrometer-sized particles. Compositional analyses by SEM-EDS identified a variety of man-made and natural particles. A few natural particles were embedded in epoxy, microtomed, and analyzed by TEM. All were polymineralic aggregates that contained olivine exhibiting sharp electron-diffraction spots, and suggesting that the materials had experienced only minimal shock-deformation, if any. One natural particle contained olivine, augite, diopside, troilite, chromite/magnetite, and hercynite, the latter existing as pristine, undeformed octahedral crystals. The olivine in two of the particles were Fo(60-70) and Fo(39-53), and thus, more equilibrated than olivines in most stratospheric particles (Fo(80-100)) These results illustrate that particle collections in Earth orbit are highly complementary to ground-based collections of cosmic dust. (C) 2000 Academic Press. C1 NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. Lockheed Martin Space Operat, Houston, TX 77058 USA. RP Horz, F (reprint author), NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, SN2, Houston, TX 77058 USA. NR 40 TC 66 Z9 66 U1 0 U2 4 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD OCT PY 2000 VL 147 IS 2 BP 559 EP 579 DI 10.1006/icar.2000.6450 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 368NY UT WOS:000090125100017 ER PT J AU Yao, XS AF Yao, XS TI Polarization insensitive antenna remoting link with frequency conversion gain SO IEEE PHOTONICS TECHNOLOGY LETTERS LA English DT Article ID SIDE-BAND AMPLIFICATION; MODULATORS AB We demonstrate a novel photonic link that simultaneously achieves frequency conversion, optical amplification, polarization sensitivity elimination, and fiber dispersion effect minimization, The link also uses low loss and less expensive phase modulators to replace intensity modulators and thus eliminates modulator bias problems. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Yao, XS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 8 Z9 8 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 1041-1135 J9 IEEE PHOTONIC TECH L JI IEEE Photonics Technol. Lett. PD OCT PY 2000 VL 12 IS 10 BP 1382 EP 1384 DI 10.1109/68.883837 PG 3 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA 374PN UT WOS:000165353700030 ER PT J AU DiDomenico, LD Rebeiz, GM AF DiDomenico, LD Rebeiz, GM TI Frequency stability in adaptive retrodirective arrays SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article AB The frequency stability of communications or remote sensing systems using phase conjugation as a means of retrodirective signaling is developed under the influence of constant rectilinear motion. The results indicate that for dynamic mobile platforms such as aircraft, helicopters, and ground vehicles the retrodirective properties of phase conjugating arrays are not guaranteed due to a possible instability of the frequency. It is shown that the frequency transmitted by each platform has a dependence on the open loop gains of the transceivers on each platform in the link. Fast and accurate reconstruction of the phase of the signal requires a high open loop gain, however, too high a gain will cause instability and eventual loss of lock, Design tradeoffs are discussed. C1 Univ Michigan, Dept Elect & Comp Syst Engn, Radiat Lab, Ann Arbor, MI 48109 USA. RP DiDomenico, LD (reprint author), CALTECH, Jet Prop Lab, MS 300-243,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 2 Z9 2 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 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD OCT PY 2000 VL 36 IS 4 BP 1219 EP 1231 PG 13 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 386TU UT WOS:000166078300016 ER PT J AU Park, S Das, S Dill, DL AF Park, S Das, S Dill, DL TI Automatic checking of aggregation abstractions through state enumeration SO IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS LA English DT Article DE abstraction; automatic verification; computer-aided verification; formal methods; model checking; multiprocessor cache coherence protocols ID VERIFICATION; PROTOCOL AB Aggregation abstraction is a way of defining a desired correspondence between an implementation of a transaction-oriented protocol and a much simpler idealized version of the same protocol. This relationship can be formally verified to prove the correctness of the implementation. We present a technique for checking aggregation abstractions automatically using a finite-state enumerator, The abstraction relation between implementation and specification is checked on-the-fly and the verification requires examining no more states than checking a simple invariant property. This technique can be used alone for verification of finite-state protocols, or as preparation for a more general aggregation proof using a general-purpose theorem-prover. We illustrate the technique on the cache coherence protocol used in the FLASH multiprocessor system. C1 NASA, RIACS, Ames Res Ctr, Moffett Field, CA 94035 USA. Stanford Univ, Comp Syst Lab, Stanford, CA 94305 USA. Stanford Univ, Dept Comp Sci, Stanford, CA 94305 USA. RP NASA, RIACS, Ames Res Ctr, Moffett Field, CA 94035 USA. EM spark@cs.stanford.edu NR 33 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0278-0070 EI 1937-4151 J9 IEEE T COMPUT AID D JI IEEE Trans. Comput-Aided Des. Integr. Circuits Syst. PD OCT PY 2000 VL 19 IS 10 BP 1202 EP 1210 DI 10.1109/43.875327 PG 9 WC Computer Science, Hardware & Architecture; Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 365LR UT WOS:000089953200010 ER PT J AU Chattopadhyay, G Miller, D LeDuc, HG Zmuidzinas, J AF Chattopadhyay, G Miller, D LeDuc, HG Zmuidzinas, J TI A dual-polarized quasi-optical SIS mixer at 550 GHz SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE dual polarization; low noise; mixer; quasi-optical; supercondoctor-insulator-superconductor ID SLOT ANTENNA AB In this paper, we describe the design, fabrication, and the performance of a low-noise dual-polarized quasi-optical superconductor-insulatur-superconductor (SIS) mixer at 550 GHz, The mixer utilizes a novel cross-slot antenna on a hyperhemispherical substrate lens, two junction tuning circuits, niobium trilayer junctions, and an IF circuit containing a lumped element 180 degrees hybrid. The antenna consists of an orthogonal pair of twin-slot antennas, and has four feed points, two for each polarization. Each feed point is coupled to a two-junction SIS mixer. The 180 degrees IF hybrid is implemented using a lumped element/microstrip circuit located inside the mixer block. Fourier transform spectrometer measurements of the mixer frequency response show good agreement with computer simulations. The measured co-polarized and cross-polarized patterns for both polarizations also agree with the theoretical predictions. The noise performance of the dual-polarized mixer is excellent, giving uncorrected receiver noise temperature of better than 115 K (double sideband) at 528 GHz for both the polarizations. C1 CALTECH, Dept Elect Engn, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. RP Chattopadhyay, G (reprint author), CALTECH, George Downs Lab Phys 320 47, Dept Phys, Pasadena, CA 91125 USA. NR 14 TC 11 Z9 11 U1 1 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD OCT PY 2000 VL 48 IS 10 BP 1680 EP 1686 DI 10.1109/22.873895 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA 363FL UT WOS:000089824400010 ER PT J AU Edmonds, LD AF Edmonds, LD TI Proton SEU cross sections derived from heavy-ion test data SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article DE charge-collection depth; charge-collection efficiency; effective flux; proton SEU cross section; SEU; single event upset ID UPSET RATE CALCULATIONS; MODEL; DIFFUSION; AVIONICS; LATCHUP; TRACKS AB Many papers have presented models for estimating proton single event upset (SEU) cross sections from heavy-ion test data, but all rigorous treatments to date are based on the sensitive volume (SV) model for charge collection. Computer simulations have already shown that, excluding devices utilizing physical boundaries for isolation, there is no well-defined SV, A more versatile description of charge collection, which includes the SV model as a special case, utilizes a charge-collection efficiency function that measures the effect that the location of ionization has on collected charge. This paper presents the first rigorous analysis that uses a generic charge-collection efficiency function to relate proton to heavy-ion cross sections. The most practical result is an upper bound far proton SEU or single event latchup (SEL) cross sections, which requires no information about the charge-collection efficiency function, except that it exists. In addition, some models previously presented by others are reproduced (or, in one case, extended) by applying the general theory to special cases, The similarities and differences between a variety of models become clear,when the models are recognized to be special cases or variations of this general theory. 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 30 TC 32 Z9 33 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD OCT PY 2000 VL 47 IS 5 BP 1713 EP 1728 DI 10.1109/23.890997 PG 16 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 388HZ UT WOS:000166176200001 ER PT J AU Zak, M AF Zak, M TI Quantum decision-maker SO INFORMATION SCIENCES LA English DT Article; Proceedings Paper CT 4th International Conference on Computational Intelligence and Neuroscience at the 5th Joint Conference on Information Sciences CY FEB 27-MAR 03, 2000 CL ATLANTIC CITY, NEW JERSEY AB A quantum device simulating human decision making process is introduced. It consists of quantum recurrent nets generating stochastic processes which represent the motor dynamics, and of classical neural nets describing evolution of probabilities of these processes which represent the mental dynamics. The autonomy of the decision making process is achieved by a feedback from mental to motor dynamics which changes the stochastic matrix based upon the probability distributions. This feedback replaces an unavailable external information by an internal knowledgebase stored in the mental model in the form of probability distributions. As a result, the coupled motormental dynamics is described by a nonlinear version of Markov chains which can decrease entropy without an external source of information. Applications to common sense based decisions as well as to evolutionary games are discussed. (C) 2000 Elsevier Science Inc. All rights reserved. C1 CALTECH, Jet Prop Lab, Ultracomp Grp, Pasadena, CA 91109 USA. RP Zak, M (reprint author), CALTECH, Jet Prop Lab, Ultracomp Grp, 4800 Oak Grove Dr,M-S 126-347, Pasadena, CA 91109 USA. NR 4 TC 11 Z9 11 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0020-0255 J9 INFORM SCIENCES JI Inf. Sci. PD OCT PY 2000 VL 128 IS 3-4 BP 199 EP 215 DI 10.1016/S0020-0255(00)00053-0 PG 17 WC Computer Science, Information Systems SC Computer Science GA 367KH UT WOS:000090059900005 ER PT J AU Harstad, K Bellan, J AF Harstad, K Bellan, J TI An all-pressure fluid drop model applied to a binary mixture: heptane in nitrogen SO INTERNATIONAL JOURNAL OF MULTIPHASE FLOW LA English DT Article DE supercritical/subcritical fluid drops ID LIQUID-MIXTURES; SUPERCRITICAL CONDITIONS; VAPORIZATION; DIFFUSION; COEFFICIENTS; COMBUSTION; HYDROGEN AB The differences between subcritical liquid drop and supercritical fluid drop behavior are shown to be a direct consequence of the length scales near the fluid drop boundary. Under subcritical, evaporative high emission rate conditions, a him layer is present in the inner part of the drop surface which contributes to the unique determination of the boundary conditions; it is this film layer in conjunction with evaporation which gives to the solution its convective-diffusive character. In contrast, under supercritical conditions the boundary conditions contain a degree of arbitrariness due to the absence of a physical surface, and the solution has then a purely diffusive character. Results from simulations of a free fluid drop under no-gravity conditions are compared to microgravity experimental data from suspended, large drop experiments at high, low and intermediary temperatures and in a range of pressures encompassing the sub- and supercritical regime. Despite the difference between the conditions of the simulations and the experiments, the time rate of variation of the drop diameter square is remarkably well predicted in the linear curve regime. Consistent with the optical measurements, in the simulations the drop diameter is determined from the location of the maximum density gradient. Detailed time-wise comparisons between simulations and data show that this location is very well predicted at 0.1 MPa. As the pressure increases, the data and simulations agreement becomes good to fair, and the possible reasons for this discrepancy are discussed. Simulations are further conducted for a small drop, such as that encountered in practical applications, over a wide range of specified, constant far field pressures. Additionally, a transient pressure simulation crossing the critical point is also conducted. Results from these simulations are analyzed and major differences between the sub- and supercritical behavior are explained. In particular, it is shown that the classical calculation of the Lewis number gives erroneous results at supercritical conditions, and that an effective Lewis number previously defined gives correct estimates of the length scales for heat and mass transfer at all pressures. (C) 2000 Published by Elsevier Science Ltd. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bellan, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 33 TC 50 Z9 52 U1 0 U2 6 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 OCT PY 2000 VL 26 IS 10 BP 1675 EP 1706 DI 10.1016/S0301-9322(99)00108-1 PG 32 WC Mechanics SC Mechanics GA 338HF UT WOS:000088412600006 ER PT J AU Hinkley, JA Proctor, DA AF Hinkley, JA Proctor, DA TI Oxidative aging of cured polymer from phyenylethynyl terminated imide oligomers SO JOURNAL OF ADVANCED MATERIALS LA English DT Article ID POLYIMIDE FILMS; COMPOSITES AB Cured phenylethynyl-terminated imide oligomers are being evaluated for use as structural resins in a High Speed Civil Transport. Oligomers with two different backbone compositions and several different initial molecular weights were cured in air and in nitrogen and the cured polymers were subjected to accelerated aging in ail: Initial stages of weight loss of powdered resins Jit Arrhenius expressions with activation energies of 143 to 182 kJ/mol. The room-temperature toughnesses of 40 mu m-thick films decreased following aging at 300-360 degrees C. Arrhenius extrapolations of lifetimes (defined as times to 10% loss of fracture toughness) exceed 10(5) hours at 177 degrees C. C1 NASA, Langley Res Ctr, CM State, Langley, VA USA. RP Hinkley, JA (reprint author), NASA, Langley Res Ctr, CM State, Langley, VA USA. NR 19 TC 4 Z9 4 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 USA SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD OCT PY 2000 VL 32 IS 4 BP 35 EP 41 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA 361DJ UT WOS:000089707100006 ER PT J AU Wolfenden, A Spann, KJ Hebsur, MG AF Wolfenden, A Spann, KJ Hebsur, MG TI Experimental investigation of vibration damping and the dynamic Young's modulus in MoSi2 and MoSi2-50Si(3)N(4)/SCS-6 at elevated temperatures SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB The effects of adding Si3N4 and SiC fibers to MoSi2 forming MoSi2-50Si(3)N(4)/SCS-6, were studied at temperatures ranging from 21 degrees C to 865 degrees C. From the Archimedes method, the measured densities of two MoSi2 samples and one composite were 6125 kg/m(3), 6113 kg/m(3) and 3705 kg/m(3) respectively at roam temperature. The Piezoelectric Ultrasonic Composite Oscillator Technique It ns employed to measure Young's modulus and damping properties. At roam temperature, Young's modulus was 322 GPa and 399 GPa for the MoSi2 samples and 235 GPa for the composite. Further mechanical damping values for MoSi2 and the composite were found to be near 3x10(-3) and 6x10(-3), respectively and independent of the strain amplitude at room temperature. Young's modulus of the composite was found to change linearly at a rate of -0.0148 GPa/degrees C. C1 Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Wolfenden, A (reprint author), Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 USA SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD OCT PY 2000 VL 32 IS 4 BP 66 EP 70 PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA 361DJ UT WOS:000089707100010 ER PT J AU Spanos, PD Berka, RB Tratskas, P AF Spanos, PD Berka, RB Tratskas, P TI Multisegment large space robot: Concept and design SO JOURNAL OF AEROSPACE ENGINEERING LA English DT Article AB A multisegment robot concept is discussed for use in space-based construction operations. The multistage robot is envisioned as a member of a class of large space robots, or space cranes, used in the assembly of advanced spacecraft. The multisegment robot involves a collection of common bodies, or segments, that are pinned together to form a snake-like, or train, configuration. The notion of shape function is used to position this serpentine robot to a prescribed location and orientation. An n-body simulation program is developed based on a Newton-Euler form of the equations of motion of the robot. Motion tests are included that compare experimental results with pertinent analytical predictions. This paper attempts to present a paradigm of theoretical and experimental study in which complex mathematical algorithms are realized in a simple physical model through an appropriate design procedure. C1 Rice Univ, Houston, TX 77005 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77005 USA. RP Spanos, PD (reprint author), Rice Univ, Mail Stop 321,6100 Main St, Houston, TX 77005 USA. NR 14 TC 3 Z9 3 U1 0 U2 0 PU ASCE-AMER SOC CIVIL ENGINEERS PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 USA SN 0893-1321 J9 J AEROSPACE ENG JI J. Aerosp. Eng. PD OCT PY 2000 VL 13 IS 4 BP 123 EP 132 DI 10.1061/(ASCE)0893-1321(2000)13:4(123) PG 10 WC Engineering, Aerospace; Engineering, Civil SC Engineering GA 358EF UT WOS:000089543700001 ER PT J AU Skofronick-Jackson, GM Wang, JR AF Skofronick-Jackson, GM Wang, JR TI The estimation of hydrometeor profiles from wideband microwave observations SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID 183 GHZ; RADAR OBSERVATIONS; CLOUD MODEL; WATER-VAPOR; TOGA COARE; PRECIPITATION; RADIOMETER; RAIN; SIMULATIONS; RETRIEVAL AB Profiles of the microphysical properties of clouds and rain cells are essential in many areas of atmospheric research and operational meteorology. To enhance the understanding of the nonlinear and underconstrained relationships between cloud and hydrometeor microphysical profiles and passive microwave brightness temperatures, estimations of cloud profiles for an anvil region, a convective region, and an updraft region of an oceanic squall were performed. The estimations relied on comparisons between radiative transfer calculations of incrementally estimated microphysical profiles and concurrent dual-altitude wideband brightness temperatures from the 22 February 1993 flight during the Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment. The wideband observations (10-220 GHz) are necessary for estimating cloud profiles reaching up to 20 km. The low frequencies enhance the rain and cloud water profiles, and the high frequencies are required to detail the higher altitude ice microphysics. A microphysical profile was estimated for each of the three regions of the storm. Each of the three estimated profiles produced calculated brightness temperatures within similar to 10 K of the observations. A majority of the total iterative adjustments were to the estimated profile's frozen hydrometeor characteristics and were necessary to match the high-frequency calculations with the observations. This requirement indicates a need to validate cloud-resolving models using high frequencies. Some difficulties matching the 37-GHz observation channels on the DC-8 and ER-2 aircraft with the calculations simulated at the two aircraft heights (similar to 11 km and 20 hn, respectively) were noted, and potential causes were presented. C1 NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Goddard Visiting Scientist Program, Seabrook, MD USA. RP Skofronick-Jackson, GM (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Code 975, Greenbelt, MD 20771 USA. RI Skofronick-Jackson, Gail/D-5354-2012 NR 35 TC 9 Z9 9 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD OCT PY 2000 VL 39 IS 10 BP 1645 EP 1656 DI 10.1175/1520-0450-39.10.1645 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 373DX UT WOS:000165274100001 ER PT J AU Rodgers, EB Adler, RF Pierce, HF AF Rodgers, EB Adler, RF Pierce, HF TI Contribution of tropical cyclones to the North Pacific climatological rainfall as observed from satellites SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID SEA-SURFACE TEMPERATURE; PRECIPITATION CHARACTERISTICS; STORM FORMATION; EL-NINO; MODEL; ENSO; SENSITIVITY; DATASET AB Tropical cyclone monthly rainfall amounts are estimated from passive microwave satellite observations for an 11-yr period. These satellite-derived rainfall amounts are used to assess the impact of tropical cyclone rainfall in altering the geographical, seasonal, and interannual distribution of the North Pacific Ocean total rainfall during June-November when tropical cyclones are most important. To estimate these tropical cyclone rainfall amounts, mean monthly rain rates are derived from passive microwave satellite observations within 144-km radius of the center of those North Pacific tropical cyclones that reached storm stage and greater. These rain-rate observations are converted to monthly rainfall amounts and then compared with those for nontropical cyclone systems. The main results of this study indicate that 1) tropical cyclones contribute 7% of the rainfall to the entire domain of the North Pacific during the tropical cyclone season and 12%, 3%, and 4% when the study area is limited to, respectively, the western, central, and eastern third of the ocean; 2) the maximum tropical cyclone rainfall is poleward (5 degrees -10 degrees latitude depending on longitude) of the maximum nontropical cyclone rainfall; 3) tropical cyclones contribute a maximum of 30% northeast of the Philippine Islands and 40% off the lower Baja California coast: 4) in the western North Pacific, the tropical cyclone rainfall lags the total rainfall by approximately two months and shows seasonal latitudinal variation following the Intertropical Convergence Zone; and 5) in general, tropical cyclone rainfall is enhanced during the El Nino years by warm SSTs in the eastern North Pacific and by the monsoon trough in the western and central North Pacific. C1 NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Lab Atmospheres, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Adler, RF (reprint author), NASA, Goddard Space Flight Ctr, Mesoscale Atmospher Proc Branch, Lab Atmospheres, Code 912, Greenbelt, MD 20771 USA. NR 38 TC 38 Z9 43 U1 1 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD OCT PY 2000 VL 39 IS 10 BP 1658 EP 1678 DI 10.1175/1520-0450(2000)039<1658:COTCTT>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 373DX UT WOS:000165274100002 ER PT J AU Christopher, SA Li, X Welch, RM Reid, JS Hobbs, PV Eck, TF Holben, B AF Christopher, SA Li, X Welch, RM Reid, JS Hobbs, PV Eck, TF Holben, B TI Estimation of surface and top-of-atmosphere shortwave irradiance in biomass-burning regions during SCAR-B SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID SINGLE-SCATTERING ALBEDO; GLOBAL RADIATION BUDGET; FOREST-FIRE SMOKE; ABSORBING AEROSOLS; OPTICAL-PROPERTIES; SATELLITE DATA; SOUTH-AMERICA; TOGA COARE; BRAZIL; SEASON AB Using in situ measurements of aerosol optical properties and ground-based measurements of aerosol optical thickness (tau (s)) during the Smoke, Clouds and Radiation-Brazil (SCAR-B) experiment, a four-stream broadband radiative transfer model is used to estimate the downward shortwave irradiance (DSWI) and top-of-atmosphere (TOA) shortwave aerosol radiative forcing (SWARF) in cloud-free regions dominated by smoke from biomass burning in Brazil. The calculated DSWI values are compared with broadband pyranometer measurements made at the surface. The results show that, for two days when near-coincident measurements of single-scattering albedo omega (0) and tau (s) are available, the root-mean-square errors between the measured and calculated DSWI for daytime data are within 30 W m(-2). For five days during SCAR-B, however, when assumptions about omega (0) have to be made and also when tau (s) was significantly higher, the differences can be as large as 100 W m(-2). At TOA, the SWARF per unit optical thickness ranges from -20 to -60 W m(-2) over four major ecosystems in South America. The results show that tau (s) and omega (0) are the two most important parameters that affect DSWI calculations. For SWARF values, surface albedos also play an important role. It is shown that omega (0) must be known within 0.05 and tau (s) at 0.55 mum must be known to within 0.1 to estimate DSWI to within 20 W m(-2). The methodology described in this paper could serve as a potential strategy for determining DSWI values in the presence of aerosols. The wavelength dependence of tau (s) and omega (0) over the entire shortwave spectrum is needed to improve radiative transfer calculations. If global retrievals of DSWI and SWARF from satellite measurements are to be performed in the presence of biomass-burning aerosols on a routine basis, a concerted effort should be made to develop methodologies for estimating omega (0) and tau (s) from satellite and ground-based measurements. C1 Univ Alabama, Dept Atmospher Sci, Huntsville, AL 35899 USA. Space & Naval Warfare Syst Ctr, Atmospher Propagat Branch D858, San Diego, CA USA. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. Raytheon Corp, Greenbelt, MD USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. RP Christopher, SA (reprint author), Univ Alabama, Dept Atmospher Sci, 977 Explorer Blvd, Huntsville, AL 35899 USA. RI Christopher, Sundar/E-6781-2011; ECK, THOMAS/D-7407-2012; Reid, Jeffrey/B-7633-2014 OI Reid, Jeffrey/0000-0002-5147-7955 NR 46 TC 27 Z9 27 U1 1 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD OCT PY 2000 VL 39 IS 10 BP 1742 EP 1753 DI 10.1175/1520-0450-39.10.1742 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 373DX UT WOS:000165274100007 ER PT J AU Seybert, CD Evans, JW Leslie, F Jones, WK AF Seybert, CD Evans, JW Leslie, F Jones, WK TI Suppression/reversal of natural convection by exploiting the temperature/composition dependence of magnetic susceptibility SO JOURNAL OF APPLIED PHYSICS LA English DT Article AB Natural convection, driven by temperature or concentration gradients or both, is an inherent phenomenon during solidification of materials on Earth. This convection has practical consequences (e.g., effecting macrosegregation) but also renders difficult the scientific examination of diffusive/conductive phenomena during solidification. It is possible to halt, or even reverse, natural convection by exploiting the variation (with temperature, for example) of the susceptibility of a material. If the material is placed in a vertical magnetic field gradient, a buoyancy force of magnetic origin arises and, at a critical field gradient, can balance the normal buoyancy forces to halt convection. At higher field gradients the convection can be reversed. The effect has been demonstrated in experiments at Marshall Space Flight Center where flow was measured by particle image velocimetry in MnCl2 solution in a superconducting magnet. In auxiliary experiments the field in the magnet and the properties of the solution were measured. Computations of the natural convection, its halting and reversal, using the commercial software FLUENT(R) were in good agreement with the measurements. (C) 2000 American Institute of Physics. [S0021-8979(00)07319-9]. C1 Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Motorola Inc, Adv Prod Technol Ctr, Ft Lauderdale, FL 33322 USA. RP Seybert, CD (reprint author), Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA. NR 6 TC 24 Z9 24 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD OCT 1 PY 2000 VL 88 IS 7 BP 4347 EP 4351 DI 10.1063/1.1289790 PG 5 WC Physics, Applied SC Physics GA 355DY UT WOS:000089371600085 ER PT J AU Wang, J Chern, CS Liu, AK AF Wang, J Chern, CS Liu, AK TI The wavelet empirical orthogonal function and its application to the analysis of internal tides SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID OREGON COAST; DECOMPOSITION AB Two powerful tools, wavelet transformation (WT) and conventional empirical orthogonal function (EOF) analysis, were combined tentatively. The combination of these two techniques might be called wavelet EOF (WEOF), and has potential for analyzing complicated signals associated with modal structures. The WT is versatile in handling transient or nonstationary time series, and EOF is capable of detecting statistically coherent modal structures from arrayed observations. WEOF inherits the advantages of both WT and EOF This paper presents some basic formulations of WEOF and postulates a method to correlate empirical and dynamical modes. Monte Carlo simulations have been used to assess the practicality of the theory. Moreover, the method is applied to a real-time series of water temperature profile measured in a submarine canyon. The results of WEOF analysis reveal some unique properties of local internal tides. including the inequality of frequency composition between the surface and internal rides and the intensity of the mode-two terdiurnal component, likely induced by nonlinear interactions between first mode waves. The material only illustrates a few of the many possible applications. Based on these demonstrations, however, WEOF has proven useful in the analysis of nonstationary time series associated with spatially modal structures. C1 Natl Taiwan Univ, Inst Oceanog, Taipei, Taiwan. NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Greenbelt, MD 20771 USA. RP Wang, J (reprint author), Natl Taiwan Univ, Inst Oceanog, POB 23-13, Taipei, Taiwan. OI Wang, Joe/0000-0002-3298-2956 NR 23 TC 5 Z9 5 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD OCT PY 2000 VL 17 IS 10 BP 1403 EP 1420 DI 10.1175/1520-0426(2000)017<1403:TWEOFA>2.0.CO;2 PG 18 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 368GW UT WOS:000090110200008 ER PT J AU Del Genio, AD Wolf, AB AF Del Genio, AD Wolf, AB TI The temperature dependence of the liquid water path of low clouds in the southern Great Plains SO JOURNAL OF CLIMATE LA English DT Article ID TOP ENTRAINMENT INSTABILITY; OPTICAL-THICKNESS; CLIMATE MODELS; GISS GCM; PARAMETERIZATION; FEEDBACK AB Satellite observations of low-level clouds have challenged the idea that increasing liquid water content with temperature combined with constant physical thickness will lead to a negative cloud optics feedback in a decadal climate change. The reasons for the satellite results are explored using 4 yr of surface remote sensing data from the Atmospheric Radiation Measurement Program Cloud and Radiation Testbed site in the southern Great Plains of the United States. It is found that low-cloud liquid water path is approximately invariant with temperature in winter but decreases strongly with temperature in summer, consistent with satellite inferences at this latitude. This behavior occurs because liquid water content shows no detectable temperature dependence while cloud physical thickness decreases with warming. Thinning of clouds with warming is observed on seasonal, synoptic, and diurnal timescales; it is most obvious in the warm sectors of baroclinic waves. Although cloud top is observed to slightly descend with warming, the primary cause of thinning is the ascent of cloud base due to the reduction in surface relative humidity and the concomitant increase in the lifting condensation level of surface air. Low-cloud liquid water path is not observed to be a continuous function of temperature. Rather, the behavior observed is best explained as a transition in the frequency of occurrence of different boundary layer types. At cold temperatures, a mixture of stratified and convective boundary layers is observed, leading to a broad distribution of liquid water path values, while at warm temperatures, only convective boundary layers with small liquid water paths, some of them decoupled, are observed. Our results, combined with the earlier satellite inferences, suggest a reexamination of the commonly quoted 1.5 degreesC lower limit for the equilibrium global climate sensitivity to a doubling of CO2, which is based on models in which liquid water increases with temperature and cloud physical thickness is constant. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Sci Syst & Applicat Inc, Inst Space Studies, New York, NY USA. RP Del Genio, AD (reprint author), NASA, Goddard Inst Space Studies, 2880, New York, NY 10025 USA. RI Del Genio, Anthony/D-4663-2012 OI Del Genio, Anthony/0000-0001-7450-1359 NR 30 TC 41 Z9 41 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD OCT 1 PY 2000 VL 13 IS 19 BP 3465 EP 3486 DI 10.1175/1520-0442(2000)013<3465:TTDOTL>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 367RJ UT WOS:000090075000008 ER PT J AU Adams, JM Bond, NA Overland, JE AF Adams, JM Bond, NA Overland, JE TI Regional variability of the Arctic heat budget in fall and winter SO JOURNAL OF CLIMATE LA English DT Article ID MEAN MERIDIONAL TRANSPORT; ENERGY FLUX; ATMOSPHERE; RADIATION; OCEAN; REANALYSES; DATASET; SYSTEM; FIELDS; ICE AB In the Arctic atmosphere, the fall cooling cycle involves the evolution of the zonally symmetric circulation in late summer into the asymmetric flow of winter. This paper uses historical reanalysis data to document how the dominant components of the Arctic heat budget influence the summer-winter transition. The spatial variability of 20-yr climatologies of 700-mb temperature and geopotential height, the net surface flux, and the horizontal convergence of eddy sensible heat fluxes are examined for September through February. The development of the zonal asymmetries in the temperature and geopotential height fields in the Arctic is linked to the land-water-ice distribution that regulates the surface fluxes and the baroclinic zones in the hemispheric circulation, which lead to regional heating/cooling by the transient and standing eddies. These eddies serve to transport the heat energy gained via the surface fluxes over the North Atlantic and North Pacific to the continental and ice-covered regions of the central Arctic, where the net surface flux is small. The transient eddies are especially important in the Atlantic and Eurasian sectors of the Arctic, while the standing eddies play the larger role in the heat budget on the Pacific side of the Arctic in early to mid-winter The Arctic oscillation (AO) has a small effect on the basinwide pattern of heating and cooling by the eddy circulations, but on smaller spatial scales there are isolated regions where the AO influences the Arctic heat budget. C1 Univ Washington, Joint Inst Study Atmosphere & Oceans, Seattle, WA 98195 USA. NOAA, Pacific Marine Environm Lab, Seattle, WA 98115 USA. RP Adams, JM (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. NR 35 TC 10 Z9 12 U1 1 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD OCT 1 PY 2000 VL 13 IS 19 BP 3500 EP 3510 DI 10.1175/1520-0442(2000)013<3500:RVOTAH>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 367RJ UT WOS:000090075000010 ER PT J AU Cowings, PS Toscano, WB AF Cowings, PS Toscano, WB TI Autogenic-feedback training exercise is superior to promethazine for control of motion sickness symptoms SO JOURNAL OF CLINICAL PHARMACOLOGY LA English DT Article AB Motion sickness symptoms affect approximately 50% of the crew during space travel and are commonly treated with intramuscular injections of promethazine. The purpose of this paper is to compare the effectiveness of three treatments for motion sickness: intramuscular injections (IM) of promethazine, a physiological training method (autogenic-feedback training exercise [AFTE]), and a no-treatment control. An earlier study tested the effects of promethazine on cognitive and psychomotor performance and motion sickness tolerance in a rotating chair. For the present paper, motion sickness tolerance, symptom reports, and physiological responses of these subjects were compared to matched subjects selected from an existing database who received either AFTE or no treatment. Three groups of I I men, between the ages of 33 and 40 years, were matched on the number of rotations tolerated during their initial rotating-chair motion sickness test. The motion sickness test procedures and the 7-day interval between tests were the same for all subjects. The drug group was tested under four treatment conditions: baseline (no injections), a 25 mg dose of promethazine, a 50 mg dose of promethazine, and a placebo of sterile saline. AFTE subjects were given four 30-minute AFTE sessions before their second, third, and fourth motion sickness tests (6 hours total). The no-treatment control subjects were only given the four rotating chair tests. Motion sickness tolerance was significantly increased after 4 hours of AFTE when compared to either 25 mg (p < 0.00003) or 50 mg (p < 0.00003) of promethazine. The control and promethazine groups did not differ AFTE subjects reported fewer or no symptoms at higher rotational velocities than subjects in the control or promethazine groups. The primary physiological effect of promethazine was an inhibition of skin conductance level. The AFTE group showed significantly less heart rate and skin conductance variability during motion sickness tests administered after training. (C) 2000 the American College of Clinical Pharmacology. C1 NASA, Ames Res Ctr, Space Life Sci Div, Moffett Field, CA 94035 USA. Univ Calif Los Angeles, Dept Psychiat, Los Angeles, CA 90024 USA. RP Cowings, PS (reprint author), NASA, Ames Res Ctr, Space Life Sci Div, Mail Stop 239-16, Moffett Field, CA 94035 USA. NR 23 TC 27 Z9 27 U1 1 U2 2 PU SAGE PUBLICATIONS INC PI THOUSAND OAKS PA 2455 TELLER RD, THOUSAND OAKS, CA 91320 USA SN 0091-2700 J9 J CLIN PHARMACOL JI J. Clin. Pharmacol. PD OCT PY 2000 VL 40 IS 10 BP 1154 EP 1165 PG 12 WC Pharmacology & Pharmacy SC Pharmacology & Pharmacy GA 356LA UT WOS:000089443700010 PM 11028255 ER PT J AU Abiteboul, S Vianu, V Fordham, B Yesha, Y AF Abiteboul, S Vianu, V Fordham, B Yesha, Y TI Relational transducers for electronic commerce SO JOURNAL OF COMPUTER AND SYSTEM SCIENCES LA English DT Article AB Electronic commerce is emerging as one of the major Web-supported applications requiring database support. We introduce and study high-level declarative specifications of business models, using an approach in the spirit of active databases. More precisely, business models are specified as relational transducers that map sequences of input relations into sequences of output relations. The semantically meaningful trace of an input-output exchange is kept as a sequence of log relations. We consider problems motivated by electronic commerce applications, such as log validation, verifying temporal properties of transducers. and comparing two relational transducers. Positive results are obtained for a restricted class of relational transducers called Spocus transducers (for semi-positive outputs and cumulative state). We argue that despite the restrictions, these capture a wide range of practically significant business models. (C) 2000 Academic Press. C1 INRIA Rocquencourt, F-78153 Le Chesnay, France. Univ Calif San Diego, La Jolla, CA 92093 USA. Oracle Corp, Redwood Shores, CA USA. NASA, Goddard Space Flight Ctr, CESDIS, Greenbelt, MD 20771 USA. RP Abiteboul, S (reprint author), INRIA Rocquencourt, BP 105, F-78153 Le Chesnay, France. NR 22 TC 23 Z9 23 U1 0 U2 3 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0022-0000 J9 J COMPUT SYST SCI JI J. Comput. Syst. Sci. PD OCT PY 2000 VL 61 IS 2 BP 236 EP 269 DI 10.1006/jcss.2000.1708 PG 34 WC Computer Science, Hardware & Architecture; Computer Science, Theory & Methods SC Computer Science GA 370QD UT WOS:000165133000005 ER PT J AU Pesnell, WD Goldberg, RA Jackman, CH Chenette, DL Gaines, EE AF Pesnell, WD Goldberg, RA Jackman, CH Chenette, DL Gaines, EE TI Variation of mesospheric ozone during the highly relativistic electron event in May 1992 as measured by the High Resolution Doppler Imager instrument on UARS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR PROTON EVENTS; MIDDLE ATMOSPHERE; PRECIPITATION EVENTS; ENERGY DEPOSITION; WATER-VAPOR; JULY 13; MAGNETOSPHERE; DEPLETION; FLUXES; MODEL AB Highly relativistic electron precipitation events (HREs) include long-lived enhancements of the Aux of electrons with E > 1 MeV into the Earth's atmosphere. HREs also contain increased fluxes of electrons with energies above 100 keV that have been predicted to cause targe depletions of mesospheric ozone. For some of the measured instantaneous values of the electron fluxes during the HRE of May 1992, relative depletions greater than 22% were predicted to occur between altitudes of 55 and 80 km, where HOx reactions cause local minima in both the ozone number density and mixing ratio altitude profiles. These ozone depictions should follow the horizontal distribution of the electron precipitation, having a distinct boundary equatorward of the L = 3 magnetic shell. To search for these effects, we have analyzed ozone data from the High Resolution Doppler Imager (HRDI) instrument on UARS. Owing to the multiple, off-track viewing angles of HRDI, observations in the region affected by the electrons are taken at similar local solar times before, during, and after the electron flux increase. Our analysis limits the relative ozone depletion to values < 10% during the very intense May 1992 HRE. We do observe decreases in the ozone mixing ratio at several points in the diurnal cycle that may be associated with the transport of water vapor into the mesosphere during May 1992. This masking of the precipitating electron effects by the seasonal variations In water vapor can complicate the detection 1 of those effects. C1 Nomad Res Inc, Bowie, MD 20716 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Lockeed Martin Adv Technol Ctr, Space Phys Dept, Palo Alto, CA 94304 USA. RP Pesnell, WD (reprint author), Nomad Res Inc, 2804 Nomad Court, Bowie, MD 20716 USA. RI Pesnell, William/D-1062-2012; Goldberg, Richard /E-1881-2012; Jackman, Charles/D-4699-2012 OI Pesnell, William/0000-0002-8306-2500; NR 39 TC 7 Z9 7 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 OCT 1 PY 2000 VL 105 IS A10 BP 22943 EP 22953 DI 10.1029/2000JA000091 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 359UN UT WOS:000089630600001 ER PT J AU Boardsen, SA Eastman, TE Sotirelis, T Green, JL AF Boardsen, SA Eastman, TE Sotirelis, T Green, JL TI An empirical model of the high-latitude magnetopause SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID WIND PLASMA CORRELATIONS; NEAR-EARTH MAGNETOTAIL; SOLAR-WIND; MAGNETIC-FIELD; POLAR CUSP; SHAPE; SIZE; MAGNETOSPHERE; WAVES; SPACECRAFT AB A quantitative, static, empirical model of the high-latitude magnetopause is developed for GSM coordinates and parameterized by dipole tilt angle (psi), solar wind pressure, and interplanetary magnetic field (IMF) B-z. We fit 691 high-latitude magnetopause crossings by the Hawkeye 1 spacecraft to a generalized second-order surface using only crossings for which both solar wind pressure and IMF data are available. These Northern Hemisphere crossings are shown to lie within the spatial coverage of Hawkeye for different bins of psi spanning the range of -35 degrees to 35 degrees, demonstrating that the psi dependence of the crossings is not due to a bias in coverage. At high latitudes, solar wind pressure and psi are found to be of major and equal importance in modeling magnetopause position. In the Northern Hemisphere the high-latitude magnetopause is displaced outward for positive psi and inward for negative psi. Additional inward displacement of the magnetopause surface is reduced for extreme negative psi values. IMF B-z dependence is separable only after the effects of psi and pressure are removed. The radial dependence on IMF B-z weakens near the cusp and becomes stronger antisunward of the cusp, where the magnetopause is displaced outward for negative IMF B-z, and inward for positive IMF B-z. This is consistent with findings along the low-latitude flanks. Both AE and Dsr dependencies are found in the high-latitude magnetopause crossings after removing Wand pressure dependencies from the crossings. This model is only valid at high latitudes, antisunward of the cusp, out to a x(GSM) value of about -5 R-E. The psi dependence of the nose is also modeled using a subset of magnetopause crossings from Roelof and Sibeck [1993] along with Hawkeye crossings below the cusp region. For positive psi the most Sunward point of the nose is displaced below the x(GSM)-y(GSM) plane. Both the nose model and the high-latitude model are in reasonable agreement with the theoretical model of Sotirelis and Meng [1999]. C1 Raytheon ITSS, Lanham, MD 20706 USA. Plasmas Int, Silver Spring, MD 20910 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. RP Boardsen, SA (reprint author), Raytheon ITSS, Lanham, MD 20706 USA. NR 44 TC 57 Z9 60 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 OCT 1 PY 2000 VL 105 IS A10 BP 23193 EP 23219 DI 10.1029/1998JA000143 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 359UN UT WOS:000089630600020 ER PT J AU Eastman, TE Boardsen, SA Chen, SH Fung, SF Kessel, RL AF Eastman, TE Boardsen, SA Chen, SH Fung, SF Kessel, RL TI Configuration of high-latitude and high-altitude boundary layers SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; DIPOLE TILT ANGLE; POLAR CUSP; ENERGY-TRANSFER; MAGNETOPAUSE; PLASMA; MAGNETOSPHERE; SHAPE; HAWKEYE-1; PRESSURE AB We report comprehensive statistical results for 4 years of Hawkeye observations totaling 1757 boundary crossings, Our objective is to use the full set of Hawkeye plasma, magnetic field, and plasma wave data to identify every cusp-associated data interval (entry layer, cusp, plasma mantle), to spatially map these regions, and to isolate the primary variables affecting their occurrence frequency and location. We find that SM coordinates best order the angular position of cusp region data intervals and that GSM coordinates are better for ordering in radial distance, especially for the plasma mantle. Dipole tilt and external pressure are the primary variables affecting high-latitude and high-altitude boundary configuration. Compared to these, the effects of IMF parameters are minor although discernable when adequate corrections are made for dipole tilt and pressure. New results on cusp flaring and indentation of the high-latitude boundary are obtained by limiting this data set in pressure, varying dipole tilt ranges, acid examining changes in boundary configuration in both SM and GSM coordinates. We find that as the dipole tilts more toward the oncoming magnetosheath plasma flow, indentation becomes enlarged and the cusp outflow region, the plasma mantle, becomes more flared out relative to the Earth-Sun line. In contrast, as the dipole lilts away from the Sun direction, cusp indentation is reduced but the cusp outflow region remains flared out compared to boundary shapes inferred from low-latitude observations. A semiempirical magnetopause model by Boardsen et nl. [this issue] compares very well with the high-latitude boundary layer observations reported here including a test for hemispheric symmetry, which is assumed by the model. C1 Plasmas Int, Silver Spring, MD 20910 USA. NASA, Goddard Space Flight Ctr, Natl Space Sci Data Ctr, Raytheon STX, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Space Phys Data Facil, Greenbelt, MD 20771 USA. Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA. RP Eastman, TE (reprint author), Plasmas Int, 1225 Edgevale Rd, Silver Spring, MD 20910 USA. RI Fung, Shing/F-5647-2012 NR 38 TC 40 Z9 40 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 OCT 1 PY 2000 VL 105 IS A10 BP 23221 EP 23238 DI 10.1029/1999JA900269 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 359UN UT WOS:000089630600021 ER PT J AU Cottaz, C Kleiner, I Tarrago, G Brown, LR Margolis, JS Poynter, RL Pickett, HM Fouchet, T Drossart, P Lellouch, E AF Cottaz, C Kleiner, I Tarrago, G Brown, LR Margolis, JS Poynter, RL Pickett, HM Fouchet, T Drossart, P Lellouch, E TI Line positions and intensities in the 2 nu(2)/nu(4) vibrational system of (NH3)-N-14 near 5-7 mu m SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID INFRARED INTENSITIES; AMMONIA; NH3; BAND; SPECTROSCOPY; PARAMETERS; MICROWAVE; CORIOLIS; STATES; MATRIX AB Line positions and intensities belonging to the vibrational system 2 nu(2)/nu(4) of ammonia N-14(3) are measured and analyzed between 1200 and 2200 cm(-1) in order to improve the molecular database. For this, laboratory spectra are obtained at 0.006 and 0.011 cm(-1) unapodized resolution and with 4% precisions for the intensities using Fourier transform spectrometers located at the Kitt Peak National Observatory and the Jet Propulsion Laboratory. The observed data contain transitions of the nu(4) fundamental band near 1626.276(1) and 1627.375(2) cm(-1) (for s and a inversion upper states, respectively) and the 2 nu(2) overtone band near 1597.470(3) and 1882.179(5) cm(-1) (for s and a inversion states, respectively). A total of 2345 lines with J' less than or equal to 15 is assigned from which 2114 line positions with J' less than or equal to 15 are fitted using an effective rotation-inversion-rotation Hamiltonian to achieve an rms of 0.003 cm(-1) with 57 molecular parameters. Over 1200 intensity measurements are modeled to +/-4.7% using 16 terms of the dipole moment expansion. A dyad model is used in order to model all the interactions expected within the 2 nu(2)/nu(4) system. The bandstrengths of 2 nu(2) (s <-- a), 2v(2) (a <-- s), and v(4) (s <-- s and a <-- a) are estimated to be 6.68(24), 0.201(5), and 116(3) cm(-2) atm(-1), respectively, at 296 K. The prediction generated by this study is available for planetary studies. (C) 2000 Academic Press. C1 Univ Paris 11, Unite Propre, CNRS, Photophys Mol Lab, F-91405 Orsay, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Observ Paris, DESPA, F-92195 Meudon, France. RP Cottaz, C (reprint author), Univ Paris 11, Unite Propre, CNRS, Photophys Mol Lab, Batiment 210, F-91405 Orsay, France. RI Fouchet, Thierry/C-6374-2017 OI Fouchet, Thierry/0000-0001-9040-8285 NR 37 TC 45 Z9 44 U1 1 U2 11 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 OCT PY 2000 VL 203 IS 2 BP 285 EP 309 DI 10.1006/jmsp.2000.8182 PG 25 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 359GY UT WOS:000089604200011 ER PT J AU Bhatia, AK Kastner, SO AF Bhatia, AK Kastner, SO TI Global and local Doppler-profile escape factors for plane-parallel geometry SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE global; local; Doppler-profile escape factors ID PROBABILITIES; CYLINDER; RATIOS; LINES AB Global (source- and direction-averaged) and local (direction-averaged) Doppler-profile escape factors for plane-parallel sources are calculated and tabulated for a range of line-center optical thicknesses tau(0), and are compared with published or derived small- and large-tau(0) approximations. Integration (averaging) over the local escape factor provides a consistency check on both the global and local evaluations. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Bhatia, AK (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 15 TC 7 Z9 7 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD OCT 1 PY 2000 VL 67 IS 1 BP 55 EP 63 DI 10.1016/S0022-4073(99)00193-4 PG 9 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 327VU UT WOS:000087815400005 ER PT J AU Gopinath, A Trinh, EH AF Gopinath, A Trinh, EH TI Compressibility effects on steady streaming from a noncompact rigid sphere SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Article ID BUBBLE; FLOW AB The problem of steady streaming around a rigid isolated sphere in a plane standing acoustic field is considered. Existing results in the literature have been generalized to allow for noncompactness of the sphere, and the influence of fluid compressibility on the streaming behavior has been included. It is found that in the high-frequency Limit of interest for which the streaming is strongest, the effective steady slip velocity at the edge of the inner boundary layer region that is responsible for driving the steady streaming in the bulk of the fluid in the outer region, has a complex variation over the surface of the sphere that depends on (i) the sphere position (with respect to the node/antinode of the acoustic field), (ii) the extent of sphere compactness, and (iii) on a well-defined function (representing compressibility effects) of the fluid Prandtl number and its ratio of specific heats. Not surprisingly, the contribution from this function is negligible when the host fluid is a liquid. The steady streaming behavior around the sphere is demonstrated with the help of flow streamlines for various cases in the diffusive limit of weak outer flow for low streaming Reynolds numbers. [S0001-4966(00)01810-5]. C1 USN, Postgrad Sch, Dept Mech Engn, Monterey, CA 93943 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gopinath, A (reprint author), USN, Postgrad Sch, Dept Mech Engn, Code ME-GK, Monterey, CA 93943 USA. NR 23 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD OCT PY 2000 VL 108 IS 4 BP 1514 EP 1520 DI 10.1121/1.1289367 PG 7 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA 364LW UT WOS:000089894700015 PM 11051478 ER PT J AU Hart, RC Balla, RJ Herring, GC AF Hart, RC Balla, RJ Herring, GC TI Optical measurement of the speed of sound in air over the temperature range 300-650 K SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Article ID INDUCED THERMAL ACOUSTICS AB Using laser-induced thermal acoustics (LITA), the speed of sound in room air (1 atm) is measured over the temperature range 300-650 K. Since the LITA apparatus maintains a fixed sound wavelength as temperature is varied, this temperature range simultaneously corresponds to a sound frequency range of 10-15 MHz. The data are compared to a published model and typically agree within 0.1%-0.4% at each of 21 temperatures. (C) 2000 Acoustical Society of America, [S0001-4966(oo)02910-6]. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23665 USA. NASA, Langley Res Ctr, AMDB, Hampton, VA 23665 USA. RP Hart, RC (reprint author), NASA, Langley Res Ctr, ICASE, Hampton, VA 23665 USA. NR 4 TC 8 Z9 8 U1 2 U2 6 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD OCT PY 2000 VL 108 IS 4 BP 1946 EP 1948 DI 10.1121/1.1289671 PG 3 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA 364LW UT WOS:000089894700059 PM 11051522 ER PT J AU Kufeld, RM Johnson, W AF Kufeld, RM Johnson, W TI The effects of control system stiffness models on the dynamic stall behavior of a helicopter SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 54th Annual Forum of the American-Helicopter-Society CY MAY 22-24, 1998 CL WASHINGTON, D.C. SP Amer Helicopter Soc AB The control system stiffness of an UH-60A helicopter was measured. A description of the measurements and the results is provided. The measured control system stiffness values were used within a comprehensive analysis, CAMRAD II, to establish a baseline calculation of the rotor system during an extreme thrust condition causing dynamic stall on the rotor. A validation of the baseline CAMRAD II model was made by comparing to measured blade shake test data and level-flight, high-thrust, flight-test data also showing dynamic stall from the UH-60A Airloads Program. Finally, an evaluation of the sensitivity of the rotor system response to different control system stiffness models was made. The calculated results indicate a moderate level of sensitivity to changes of control system stiffness in the presence of dynamic stall. This finding in itself is an important determination, as this paper narrows the range of possibilities, which are assumed to be important to dynamic stall predictions by demonstrating the effects of control system stiffness on predictions and thereby moving researchers to focus on other attributes such as three-dimensional aerodynamics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kufeld, RM (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 10 TC 11 Z9 11 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 2000 VL 45 IS 4 BP 263 EP 269 PG 7 WC Engineering, Aerospace SC Engineering GA 465QX UT WOS:000170602400003 ER PT J AU Nixon, MW Piatak, DJ Corso, LM Popelka, DA AF Nixon, MW Piatak, DJ Corso, LM Popelka, DA TI Aeroelastic tailoring for stability augmentation and performance enhancements of tiltrotor aircraft SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT 55th Annual Forum of the American-Helicopter-Society CY MAY 25-27, 1999 CL MONTREAL, CANADA SP Amer Helicopter Soc AB The requirements for increased speed and productivity for tiltrotors has spawned several investigations associated with proprotor aeroelastic stability augmentation and aerodynamic performance enhancements. Included among these investigations is a focus on passive aeroelastic tailoring concepts which exploit the anisotropic capabilities of fiber composite materials. Researchers at Langley Research Center and Bell Helicopter have devoted considerable effort to assess the potential for using these materials to obtain aeroelastic responses which are beneficial to the important stability and performance considerations of tiltrotors. Both experimental and analytical studies have been completed to examine acroelastic tailoring concepts for the tiltrotor, applied either to the wing or to the rotor blades. This paper reviews some of the results obtained in these aeroelastic tailoring investigations and discusses the relative merits associated with these approaches. C1 USA, Langley Res Ctr, Vehicle Technol Directorate, Hampton, VA 23665 USA. NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA USA. Bell Helicopter Textron Inc, Rotor Dynam, Ft Worth, TX USA. RP Nixon, MW (reprint author), USA, Langley Res Ctr, Vehicle Technol Directorate, Hampton, VA 23665 USA. NR 20 TC 4 Z9 4 U1 1 U2 1 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 2000 VL 45 IS 4 BP 270 EP 279 PG 10 WC Engineering, Aerospace SC Engineering GA 465QX UT WOS:000170602400004 ER PT J AU Piatak, DJ Kunz, DL AF Piatak, DJ Kunz, DL TI An experimental testbed for investigations of tiltrotor vibration control SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB An experimental, dynamically scaled, tiltrotor model was developed for use as a testbed for investigations of vibration control strategies. The model was created from a simple design, and its characteristics were determined from ground vibration testing. These results showed that the frequencies and mode shapes of the model were representative of a full-scale tiltrotor aircraft. To test the fidelity of the model, the Multipoint Adaptive Vibration Suppression System (MAVSS) was implemented to mirror tests performed using the semispan Wing and Rotor Aeroelastic Test System (WRATS) in the NASA Langley Transonic Dynamics Tunnel. Test cases using a single control actuator to simulate an active flaperon confirmed that any one of the wing response components could be suppressed effectively. With two control actuators, all three wing responses could also be minimized effectively. The similarity of the results of these tests to the WRATS tests demonstrates the potential of this model to be a tool in evaluating the effectiveness of new vibration control strategies for tiltrotor aircraft. C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. Old Dominion Univ, Dept Aerosp Engn, Norfolk, VA USA. RP Piatak, DJ (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 12 TC 0 Z9 0 U1 0 U2 3 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 2000 VL 45 IS 4 BP 280 EP 283 PG 4 WC Engineering, Aerospace SC Engineering GA 465QX UT WOS:000170602400005 ER PT J AU Caradonna, F Kitaplioglu, C McCluer, M Baeder, J Leishman, JG Berezin, C Visintainer, J Bridgeman, J Burley, C Epstein, R Lyrintzis, A Koutsavdis, E Rahier, G Delrieux, Y Rule, J Bliss, D AF Caradonna, F Kitaplioglu, C McCluer, M Baeder, J Leishman, JG Berezin, C Visintainer, J Bridgeman, J Burley, C Epstein, R Lyrintzis, A Koutsavdis, E Rahier, G Delrieux, Y Rule, J Bliss, D TI Methods for the prediction of blade-vortex interaction noise SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article; Proceedings Paper CT American-Helicopter-Society-Technical-Specialists Meeting for Rotorcraft Acoustics and Aerodynamics CY OCT 28-30, 1997 CL WILLIAMSBURG, VIRGINIA SP Amer Helicopter Soc, Tech Specialists ID HELICOPTER ROTORS AB This paper compares aeroacoustic methods for the prediction of parallel blade-vortex interaction noise using data from a specialized rotor test. The test, performed in the NASA Ames 80- by 120-Foot Wind Tunnel, involved a small-scale rotor interacting with a vortex generated by a wing mounted upstream. These data were the focus of a working group that compared a wide range of methods for the prediction of BVI noise. The aerodynamic models include computational fluid dynamics, boundary element, and indicial methods. Acoustic methods include Kirchhoff methods and the Ffowes-Williams Hawkings approach. The comparisons of computed and measured surface pressure data reveal a number of differences, none of which seem to have major acoustic significance. Comparisons of computed and measured far-field pressures show that BVI acoustics is generally well predicted when the blade aerodynamics are well defined, with more variations being found between the Kirchhoff methods. Within the limitations of the present test, this indicates that BVI noise is reasonably well predicted when vortex parameters (location, circulation, and core radius) are accurately known. C1 NASA, Ames Res Ctr, Army NASA Rotorcraft Div, Moffett Field, CA 94035 USA. Univ Maryland, College Pk, MD 20742 USA. United Technol Corp, Sikorsky Aircraft Div, Hartford, CT 06101 USA. Flow Anal Inc, Woodside Summit Grp, Albuquerque, NM USA. Boeing Co, Seattle, WA 98124 USA. Purdue Univ, W Lafayette, IN 47907 USA. Off Natl Etud & Rech Aerosp, Toulouse, France. Duke Univ, Durham, NC 27706 USA. RP Caradonna, F (reprint author), NASA, Ames Res Ctr, Army NASA Rotorcraft Div, Moffett Field, CA 94035 USA. NR 29 TC 2 Z9 3 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD OCT PY 2000 VL 45 IS 4 BP 303 EP 317 PG 15 WC Engineering, Aerospace SC Engineering GA 465QX UT WOS:000170602400008 ER PT J AU Eluszkiewicz, J Hemler, RS Mahlman, JD Bruhwiler, L Takacs, LL AF Eluszkiewicz, J Hemler, RS Mahlman, JD Bruhwiler, L Takacs, LL TI Sensitivity of age-of-air calculations to the choice of advection scheme SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID GENERAL-CIRCULATION MODEL; SEMI-LAGRANGIAN TRANSPORT; SHAPE-PRESERVING INTERPOLATION; TRACE CONSTITUENT TRANSPORT; ISENTROPIC-SIGMA-MODEL; CARBON-DIOXIDE; STRATOSPHERIC TRANSPORT; RESIDUAL CIRCULATION; TROPOSPHERE EXCHANGE; NUMERICAL ADVECTION AB The age of air has recently emerged as a diagnostic of atmospheric transport unaffected by chemical parameterizations, and the features in the age distributions computed in models have been interpreted in terms of the models' large-scale circulation field. This study shows, however, that in addition to the simulated large-scale circulation, three-dimensional age calculations can also be affected by the choice of advection scheme employed in solving the tracer continuity equation. Specifically, using the 3.0 degrees latitude x 3.6 degrees longitude and 40 vertical level version of the Geophysical Fluid Dynamics Laboratory SKYHI GCM and six online transport schemes ranging from Eulerian through semi-Lagrangian to fully Lagrangian, it will be demonstrated that the oldest ages are obtained using the nondiffusive centered-difference schemes while the youngest ages are computed with a semi-Lagrangian transport (SLT) scheme. The centered-difference schemes are capable of producing ages older than 10 years in the mesosphere, thus eliminating the "young bias" found in previous age-of-air calculations. At this stage, only limited intuitive explanations can be advanced for this sensitivity of age-of-air calculations to the choice of advection scheme. In particular, age distributions computed online with the National Center for Atmospheric Research Community Climate Model (MACCM3) using different Varieties of the SLT scheme are substantially older than the SKYHI SLT distribution. The different varieties, including a noninterpolating-in-the-vertical version (which is essentially centered-difference in the vertical), also produce a narrower range of age distributions than the suite of advection schemes employed in the SKYHI model. While additional MACCM3 experiments with a wider range of schemes would be necessary to provide more definitive insights, the older and less variable MACCM3 age distributions can plausibly be interpreted as being due to the semi-implicit semi-Lagrangian dynamics employed in the MACCM3. This type of dynamical core (employed with a 60-min time step) is likely to reduce SLT's interpolation errors that are compounded by the short-term variability characteristic of the explicit centered-difference dynamics employed in the SKYHI model (time step of 3 min). In the extreme case of a very slowly varying circulation, the choice of advection scheme has no effect on two-dimensional (latitude-height) age-of-air calculations, owing to the smooth nature of the transport circulation in 2D models. These results suggest that nondiffusive schemes may be the preferred choice for multiyear simulations of tracers not overly sensitive to the requirement of monotonicity (this category includes many greenhouse gases). At the same rime, age-of-air calculations offer a simple quantitative diagnostic of a scheme's long-term diffusive properties and may help in the evaluation of dynamical cores in multiyear integrations. On the other hand, the sensitivity of the computed ages to the model numerics calls for caution in using age of air as a diagnostic of a GCM's large-scale circulation field. C1 Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. NOAA, Geophys Fluid Dynam Lab, Princeton, NJ USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Eluszkiewicz, J (reprint author), Atmospher & Environm Res Inc, 840 Mem Dr, Cambridge, MA 02139 USA. NR 63 TC 33 Z9 33 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD OCT 1 PY 2000 VL 57 IS 19 BP 3185 EP 3201 DI 10.1175/1520-0469(2000)057<3185:SOAOAC>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 362MW UT WOS:000089782600001 ER PT J AU Boysen, DA Chisholm, CRI Haile, SM Narayanan, SR AF Boysen, DA Chisholm, CRI Haile, SM Narayanan, SR TI Polymer solid acid composite membranes for fuel-cell applications SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID PHASE-TRANSITIONS; PROTON CONDUCTIVITY; CSHSO4; PRESSURE; SYSTEM AB A systematic study of the conductivity of polyvinylidene fluoride (PVDF) and CsHSO4 composites, containing 0 to 100% CsHSO4, has been carried out. The polymer, with its good mechanical properties. served as a supporting matrix for the high proton conductivity inorganic phase. The conductivity of composites exhibited a sharp increase with temperature at 142 degrees C, characteristic of the superprotonic phase transition of CsHSO4. At high temperature (160 degrees C), the dependence of conductivity on vol % CsHSO4 was monotonic and revealed a percolation threshold of similar to 10 vol %. Al low temperature (100 degrees C), a maximum in the conductivity at similar to 80 vol % CsHSO4 was observed. Results of preliminary fuel cell measurements are presented. (C) 2000 The Electrochemical Society. S0013-4651(00)02-071-1. All rights reserved. C1 CALTECH, Dept Mat Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Boysen, DA (reprint author), CALTECH, Dept Mat Sci, Pasadena, CA 91125 USA. RI Panithipongwut, Chatr/A-1648-2013; Haile, Sossina/I-3448-2015 NR 17 TC 56 Z9 60 U1 2 U2 15 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 65 SOUTH MAIN STREET, PENNINGTON, NJ 08534 USA SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD OCT PY 2000 VL 147 IS 10 BP 3610 EP 3613 DI 10.1149/1.1393947 PG 4 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA 359GJ UT WOS:000089602900007 ER PT J AU Li, XF Sui, CH Lau, KM Adamec, D AF Li, XF Sui, CH Lau, KM Adamec, D TI Effects of precipitation on ocean mixed-layer temperature and salinity as simulated in a 2-D coupled ocean-cloud resolving atmosphere model SO JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN LA English DT Article ID EQUATORIAL WESTERN PACIFIC; TOGA-COARE; DIURNAL-VARIATIONS; EL-NINO; VARIABILITY; CONVECTION; RADIATION; DECADE; POOL; OGCM AB Impacts of small scale ocean disturbances induced by atmospheric precipitation on ocean mixed-layer heat and salt budgets are investigated by analyzing the differences in ocean mixed-layers between 1-D and 2-D ocean simulations using a two-dimensional coupled ocean-cloud resolving atmosphere model. The cloud resolving atmosphere model of coupled system is forced by large-scale atmospheric vertical velocities derived from the TOGA COARE observations during a selected seven-day period. Coupled experiments with 1-D and 2-D ocean models show that differences in the horizontal-mean mixed-layer salinity and temperature could be as large as 0.3 PSU and 0.4 degreesC respectively. Shallow mixed layers over the convective areas due to the fresh water flux and deep mixed layers over the convection-free areas due to heat loss result in moderate deepening of the horizontal-mean mixed layers during nighttime in the 2-D ocean simulation while the persistent rainfall maintains shallow mixed layers in the 1-D ocean simulation. Such mixed-layer depth differences are responsible for the differences in saline entrainment and cooling rates, and thus differences in salinity and temperature. Heavy rainfall occurs over convective areas embedded in broad non-convective or clear areas, whereas diurnal signals over whole model areas yield high spatial correlation of surface heat flux. Thus, fresh water flux exhibits larger spatial fluctuations than surface heat flux. As a result, mixed-layer salinities contribute more to the density differences than do mixed-layer temperatures. C1 NASA, Goddard Space Flight Ctr, EIT, Greenbelt, MD 20771 USA. RP Li, XF (reprint author), NASA, Goddard Space Flight Ctr, EIT, Code 913, Greenbelt, MD 20771 USA. EM xli@climate.gsfc.nasa.gov RI Li, Xiaofan/F-5605-2010; Li, Xiaofan/G-2094-2014; Lau, William /E-1510-2012; OI Lau, William /0000-0002-3587-3691; SUI, CHUNG-HSIUNG/0000-0003-2842-5660 NR 25 TC 14 Z9 14 U1 0 U2 2 PU METEOROLOGICAL SOC JAPAN PI TOKYO PA C/O JAPAN METEOROLOGICAL AGENCY 1-3-4 OTE-MACHI, CHIYODA-KU, TOKYO, 100-0004, JAPAN SN 0026-1165 EI 2186-9057 J9 J METEOROL SOC JPN JI J. Meteorol. Soc. Jpn. PD OCT PY 2000 VL 78 IS 5 BP 647 EP 659 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 384GW UT WOS:000165935300009 ER PT J AU Papalexandris, MV Redding, DC AF Papalexandris, MV Redding, DC TI Calculation of diffraction effects on the average phase of an optical field SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID NUMERICAL EVALUATION; FAST ALGORITHMS; INTEGRALS; APPROXIMATIONS; GEOMETRY AB We report on algorithms for the computation of the average phase of a beam over a detector in the near field. The basic idea is to reconstruct the optical field numerically and then use a quadrature algorithm to evaluate the quantity of interest. The various algorithms that employ discrete Fourier transform techniques for the computation of the field are described, and numerical tests that assess the accuracy of these algorithms are presented. No particular algorithm delivers the desired accuracy over the entire range of Fresnel numbers of interest, but each can produce satisfactory results within a particular range. Finally, new methods to evaluate the average phase are introduced, and their efficiency is assessed. (C) 2000 Optical Society of America [S0740-3232(00)02510-2] OCIS codes: 000.4430, 070.2580, 050.1960, 070.2590. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Papalexandris, MV (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 23 TC 8 Z9 8 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD OCT PY 2000 VL 17 IS 10 BP 1763 EP 1772 DI 10.1364/JOSAA.17.001763 PG 10 WC Optics SC Optics GA 359HA UT WOS:000089604400008 PM 11028524 ER PT J AU Jarzembski, MA Srivastava, V AF Jarzembski, MA Srivastava, V TI Spectral analysis of vibrational harmonic motion by use of a continuous-wave CO2 Doppler lidar SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID BACKSCATTER; CALIBRATION; SPECKLE AB Vibrational motion of a harmonic oscillator was investigated with a focused continuous-wave (cw) CO2 Doppler lidar at 9.1-mu m wavelength. A continuum of frequencies along with many discrete, equally spaced, resonant frequency modes was observed. The frequency modes are similar in structure to the oscillatory longitudinal modes of a laser cavity and arise because of interference of the natural resonant frequency of the oscillator with specific frequencies within the continuum. Each consecutive resonant frequency mode occurred for a movement of the oscillator much less than the wavelength of incident lidar radiation. For vigorous vibration of the oscillator, the observed spectra may be indicating nonlinear motion. (C) 2000 Optical Society of America [S0740-3232(00)00910-8]. OCIS codes: 030.1640, 030.4010. 120.7280, 260.3160, 280.3340, 280.3640. C1 NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35805 USA. Univ Space Res Assoc, Global Hydrol & Climate Ctr, Huntsville, AL 35805 USA. RP Jarzembski, MA (reprint author), NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, 320 Sparkman Dr, Huntsville, AL 35805 USA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD OCT PY 2000 VL 17 IS 10 BP 1840 EP 1845 DI 10.1364/JOSAA.17.001840 PG 6 WC Optics SC Optics GA 359HA UT WOS:000089604400016 PM 11028532 ER PT J AU Lock, JA Adler, CL Hovenac, EA AF Lock, JA Adler, CL Hovenac, EA TI Exterior caustics produced in scattering of a diagonally incident plane wave by a circular cylinder: semiclassical scattering theory analysis SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID ORDER RAINBOW; EVOLUTION; DROPS AB Rie use the semiclassical limit of electromagnetic wave scattering theory to determine the properties of the exterior caustics of a diagonally incident plane wave scattered by an infinitely long homogeneous dielectric circular cylinder in both the near zone and the far zone. The transmission caustic has an exterior/interior cusp transition as the tilt angle of the incident beam is increased, and each of the rainbow caustics has a far-zone rainbow/exterior cusp transition and an exterior/interior cusp transition as the incident beam tilt angle is increased. We experimentally observe and analyze both transitions of the first-order rainbow. We also compare the predictions of the semiclassical approximation with those of ray theory and exact electromagnetic wave scattering theory. (C) 2000 Optical Society of America [S0740-3232(00)01010-3]. OCIS codes: 080.1510, 290.4020. C1 Cleveland State Univ, Dept Phys, Cleveland, OH 44115 USA. St Marys Coll Maryland, Dept Phys, St Marys City, MD 20686 USA. NASA, Fed Data Corp, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Lock, JA (reprint author), Cleveland State Univ, Dept Phys, Cleveland, OH 44115 USA. NR 28 TC 21 Z9 21 U1 1 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD OCT PY 2000 VL 17 IS 10 BP 1846 EP 1856 DI 10.1364/JOSAA.17.001846 PG 11 WC Optics SC Optics GA 359HA UT WOS:000089604400017 PM 11028533 ER PT J AU Wang, TS AF Wang, TS TI Effect of fence on linear aerospike plume-induced base-heating physics SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA 33rd Thermophysics Conference CY JUN 28-JUL 01, 1999 CL NORFOLK, VIRGINIA SP Amer Inst Aeronaut & Astronaut ID CLUSTERED NOZZLE CONFIGURATION; FLOWFIELD; ENVIRONMENT AB A computational heat transfer analysis is conducted to study the effect of the presence of an engine fence on the X-33 linear aerospike plume-induced base heating during vehicle ascent. A fence is an extension of the plug side wall that reduces the plume spillage. A detailed three-dimensional thermoflowfield of the entire vehicle is computed such that an accurate freestream Row environment is assured for the base-dow development. The computational methodology is based on a finite difference, viscous flow, chemically reacting, pressure-based computational fluid dynamics formulation and a finite volume, spectral-line-based weighted sum of gray gases absorption computational radiation heat transfer formulation. The computed base-flow physics are analyzed and compared with those of a subscale model hot-flow test. The effect of base bleed is also analyzed. C1 NASA, George C Marshall Space Flight Ctr, Appl Fluid Dynam Anal Grp, Huntsville, AL 35812 USA. RP Wang, TS (reprint author), NASA, George C Marshall Space Flight Ctr, Appl Fluid Dynam Anal Grp, Huntsville, AL 35812 USA. NR 23 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 2000 VL 14 IS 4 BP 457 EP 463 DI 10.2514/2.6553 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 368XE UT WOS:000090142100001 ER PT J AU Stallcop, JR Partridge, H Pradhan, A Levin, E AF Stallcop, JR Partridge, H Pradhan, A Levin, E TI Potential energies and collision integrals for interactions of carbon and nitrogen atoms SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID TRANSPORT CROSS-SECTIONS; CONFIGURATION-INTERACTION CALCULATIONS; MOLECULAR WAVE-FUNCTIONS; COUPLED-CLUSTER THEORY; BASIS-SETS; BENCHMARK CALCULATIONS; DISSOCIATION-ENERGIES; ELECTRON CORRELATION; HARTREE-FOCK; STATES AB Potential energies for Ct and CN are calculated by a configuration interaction method fur these states for which the molecule dissociates into ground state atoms. The potential energy curves are shown graphically; parameters determined from the potential energy wells are tabulated and compared with the corresponding data available from measurements. The potential energies of the 7 Sigma (+)(u) and A(15)Sigma (+)(g) states of N(2) are computed from very accurate state-of-the-art molecular structure calculations and improved using the results of spectroscopic measurements, respectively. Transport cross sections are tabulated for a broad range of collision energies. Collision integrals are determined from the cross sections; the C-C and C-N results are tabulated for temperatures in the range 300-30,000 K. The improved collision integrals for N-N interactions differ from the corresponding results of an existing tabulation by a small insignificant amount. The scattering results are used to validate simple methods fur estimating collision integrals and to examine the diffusion, viscosity, and thermal diffusion in a gas composed of carbon and nitrogen atoms. C1 NASA, Ames Res Ctr, Space Technol Div, Computat Chem Branch, Moffett Field, CA 94035 USA. SVG Lithog, Adv Programs, Wilton, CT USA. Eloret Corp, Thermosci Inst, Moffett Field, CA 94035 USA. RP Stallcop, JR (reprint author), NASA, Ames Res Ctr, Space Technol Div, Computat Chem Branch, M-S 230-3, Moffett Field, CA 94035 USA. NR 58 TC 25 Z9 25 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 2000 VL 14 IS 4 BP 480 EP 488 DI 10.2514/2.6570 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 368XE UT WOS:000090142100004 ER PT J AU Walker, DG Scott, EP Nowak, RJ AF Walker, DG Scott, EP Nowak, RJ TI Estimation methods for two-dimensional conduction effects of shock-shock heat fluxes SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB Highly localized heating rates occur in extreme thermal environments, such as shock-shock interaction at hypersonic speeds. Experimental estimation of heat Bur usually involves measurement of discrete unsteady surface temperatures on low conductivity materials that are chosen to reduce conduction effects. Typically, temperature measurements are reduced to heat fluxes using one-dimensional conduction techniques. However, lateral conduction from localized high heat Bur regions into low heat Bur regions is significant and influences the one-dimensional solution. The one-dimensional solution also suffers mathematical instabilities. To evaluate the nonuniform, unsteady surface flux from measured temperatures, an inverse technique was devised that damps instabilities in the temporal direction and resolves large and sudden flux changes in the spatial direction. Based on previous work, a simple inverse method was used in time, and a function specification method was used in space. Furthermore, a technique was devised to expedite the solution by marching in space as well as in time. The new multidimensional inverse method was found to resolve steep spatial gradients more accurately in Bur than a one-dimensional method. Furthermore, the inverse procedure exhibits better stability than a multidimensional forward technique. C1 Vanderbilt Univ, Dept Engn Mech, Nashville, TN 37212 USA. Virginia Polytech Inst & State Univ, Dept Mech Engn, Blacksburg, VA 24061 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Walker, DG (reprint author), Vanderbilt Univ, Dept Engn Mech, 101 Olin Hall, Nashville, TN 37212 USA. RI Walker, Don/B-3718-2012 OI Walker, Don/0000-0002-6061-048X NR 22 TC 13 Z9 13 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD OCT-DEC PY 2000 VL 14 IS 4 BP 533 EP 539 DI 10.2514/2.6554 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA 368XE UT WOS:000090142100010 ER PT J AU van de Wall, AG Kadambi, JR Adamczyk, JJ AF van de Wall, AG Kadambi, JR Adamczyk, JJ TI A transport model for the deterministic stresses associated with turbomachinery blade row interactions SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 45th International Gas Turbine and Aeroengine Congress and Exhibition CY MAY 08-11, 2000 CL MUNICH, GERMANY ID SIMULATION; FLOW AB The unsteady process resulting from the interaction of upstream vortical structures with a downstream blade row in turbomachines can have a significant impact on the machine efficiency. The upstream vortical structures or disturbances are transported by the mean flow of the downstream blade row, redistributing the time-average unsteady kinetic energy (K) associated with the incoming disturbance. A transport model was developed to take this process into account in the computation of time-averaged multistage turbomachinery flows. The model was applied to compressor and turbine geometry. For compressors, the K associated with upstream two-dimensional wakes and three-dimensional tip clearance flows is reduced as a result of their interaction with a downstream blade row. This reduction results from inviscid effects as well as viscous effects and reduces the loss associated with the upstream disturbance. Any disturbance passing through a compressor blade row results in a smaller loss than if the disturbance was mixed-out prior to entering the blade row. For turbines, the K associated with upstream two-dimensional wakes and three-dimensional tip clearance flows are significantly amplified by inviscid effects as a result of the interaction with a downstream turbine blade row. Viscous effects act to reduce the amplification of the K by inviscid effects but result in a substantial loss. Two-dimensional wakes and three-dimensional tip clearance flows passing through a turbine blade row result in a larger loss than if these disturbances were mixed-out prior to entering the blade row. [S0889-504X(00)01804-3]. C1 Case Western Reserve Univ, Dept Mech & Aerosp Engn, Cleveland, OH 44106 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP van de Wall, AG (reprint author), Gen Elect Aircraft Engines, Cincinnati, OH USA. NR 21 TC 11 Z9 11 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD OCT PY 2000 VL 122 IS 4 BP 593 EP 603 DI 10.1115/1.1312802 PG 11 WC Engineering, Mechanical SC Engineering GA 404NM UT WOS:000167106700001 ER PT J AU Dorney, DJ Griffin, LM Huber, FW AF Dorney, DJ Griffin, LM Huber, FW TI A study of the effects of tip clearance in a supersonic turbine SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 45th International Gas Turbine and Aeroengine Congress and Exhibition CY MAY 08-11, 2000 CL MUNICH, GERMANY ID NUMERICAL-SIMULATION; COMPRESSOR; FLOW; STAGE AB Flow unsteadiness is a major factor in turbine performance and durability. This is especially true if the turbine is a high work design, compact, transonic, supersonic, counter-rotating, or uses a dense drive gas. The vast majority of modern rocket turbine designs fall into these categories. In this study a parallelized unsteady three-dimensional Navier-Stokes analysis has been used to study the effects of tip clearance on the transient and time-averaged flow fields in a supersonic turbine. The predicted results indicate improved performance in the simulation including tip clearance. The main sources of the performance gains were: (1) a weakened shock system in the case with tip clearance, and (2) the fact that the reductions in the shock losses were greater than the losses introduced by tip clearance. [SO889-504X(00)02404-1]. C1 Virginia Commonwealth Univ, Dept Mech Engn, Richmond, VA 23284 USA. NASA, George C Marshall Space Flight Ctr, Fluid Dynam Anal Branch, Marshall Space Flight Ct, AL 35812 USA. Riverbend Design Serv, Palm Beach Gardens, FL 33418 USA. RP Dorney, DJ (reprint author), Virginia Commonwealth Univ, Dept Mech Engn, Med Coll Virginia Campus, Richmond, VA 23284 USA. NR 14 TC 6 Z9 6 U1 3 U2 5 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD OCT PY 2000 VL 122 IS 4 BP 674 EP 683 DI 10.1115/1.1290400 PG 10 WC Engineering, Mechanical SC Engineering GA 404NM UT WOS:000167106700011 ER PT J AU Azad, GS Han, JC Teng, SY Boyle, RJ AF Azad, GS Han, JC Teng, SY Boyle, RJ TI Heat transfer and pressure distributions on a gas turbine blade tip SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 45th International Gas Turbine and Aeroengine Congress and Exhibition CY MAY 08-11, 2000 CL MUNICH, GERMANY ID FLOW; EFFICIENCY AB Heat transfer coefficient and static pressure distributions are experimentally investigated on a gas turbine blade tip in a five-bladed stationary linear cascade. The blade is a two-dimensional model of a first-stage gas turbine rotor blade with a blade tip profile of a GE-E-3 aircraft gas turbine engine rotor blade. The flow condition in the test cascade corresponds to an overall pressure ratio of 1.32 and exit Reynolds number based on axial chord of 1.1 x 10(6). The middle 3-blade has a variable tip gap clearance. All measurements are made at three different tip gap clearances of about 1, 1.5, and 2.5 percent of the blade span. Heat transfer measurements are also made at two different turbulence intensity levels of 6.1 and 9.7 percent at the cascade inlet. Static pressure measurements are made in the midspan and the near-tip regions as well as on the shroud surface, opposite the blade tip surface. Detailed heat transfer coefficient distributions on the plane tip surface are measured using a transient liquid crystal technique. Results show various regions of high and low heat transfer coefficient distributions. Tip clearance has a significant influence on local tip heat transfer coefficient distribution. Heat transfer coefficient also increases about 15-20 percent along the leakage flow path at higher turbulence intensity level of 9.7 over 6.1 percent. [S0889-504X(00)00404-9]. C1 Texas A&M Univ, Dept Mech Engn, Turbine Heat Transfer Lab, College Stn, TX 77843 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Azad, GS (reprint author), Texas A&M Univ, Dept Mech Engn, Turbine Heat Transfer Lab, College Stn, TX 77843 USA. NR 18 TC 82 Z9 86 U1 6 U2 19 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD OCT PY 2000 VL 122 IS 4 BP 717 EP 724 DI 10.1115/1.1308567 PG 8 WC Engineering, Mechanical SC Engineering GA 404NM UT WOS:000167106700016 ER PT J AU Azad, GS Han, JC Boyle, RJ AF Azad, GS Han, JC Boyle, RJ TI Float transfer and flow on the squealer tip of a gas turbine blade SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 45th International Gas Turbine and Aeroengine Congress and Exhibition CY MAY 08-11, 2000 CL MUNICH, GERMANY ID HEAT-TRANSFER; EFFICIENCY; LEAKAGE AB Experimental investigations are performed to measure the detailed heat transfer coefficient and static pressure distributions on the squealer tip of a gas turbine blade in a five-bladed stationary linear cascade. The blade is a two-dimensional model of a modern first-stage gas turbine rotor blade with a blade tip profile of GE-E-3 aircraft gas turbine engine rotor blade. A squealer (recessed) tip with a 3.77 percent recess is considered here. The data on the squealer tip are also compared with a flat tip case. All measurements are made at three different tip gap clearances of about 1, 1.5, and 2.5 percent of the blade span. Two different turbulence intensities of 6.1 and 9.7 percent at the cascade inlet are also considered for heat transfer measurements. Static pressure measurements are made in the midspan and near-tip regions, as well as on the shroud surface opposite to the blade tip surface. The flow condition in the test cascade corresponds to an overall pressure ratio of 1.32 and an exit Reynolds number based on the axial chord of 1.1 x 10(6). A transient liquid crystal technique is used to measure the heat transfer coefficients. Results show that the heat transfer coefficient oil the cavity surface and rim increases with an increase in tip clearance. The heat transfer coefficient on the rim is higher than the cavity surface. The cavity surface has a higher hear transfer coefficient near the leading edge legion than the trailing edge region. The heat transfer coefficient on the pressure side rim and trailing edge region is higher at a higher turbulence intensity level of 9.7 over 6.1 percent case. However, no significant difference in local heat transfer coefficient is observed inside the cavity and the suction side rim for the two turbulence intensities. The squealer tip blade provides a lower overall heat transfer coefficient when compared to the flat tip blade. [S0889-504X(00)00504-3]. C1 Texas A&M Univ, Dept Mech Engn, Turbine Heat Transfer Lab, College Stn, TX 77843 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Azad, GS (reprint author), Texas A&M Univ, Dept Mech Engn, Turbine Heat Transfer Lab, College Stn, TX 77843 USA. NR 20 TC 76 Z9 80 U1 1 U2 5 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD OCT PY 2000 VL 122 IS 4 BP 725 EP 732 DI 10.1115/1.1311284 PG 8 WC Engineering, Mechanical SC Engineering GA 404NM UT WOS:000167106700017 ER PT J AU Van Zante, DE Strazisar, AJ Wood, JR Hathaway, MD Okiishi, TH AF Van Zante, DE Strazisar, AJ Wood, JR Hathaway, MD Okiishi, TH TI Recommendations for achieving accurate numerical simulation of tip clearance flows in transonic compressor rotors SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT International Gas Turbine and Aeroengine Congress and Exhibition CY JUN 07-10, 1999 CL INDIANAPOLIS, INDIANA ID 3-DIMENSIONAL VISCOUS-FLOW AB The tip clearance flows of transonic compressor rotors are important because they have a significant impact on rotor and stage performance. A wall-bounded shear layer formed by the relative motion between the overtip leakage flow and the shroud wall is found to have a major influence on the development of the tip clearance flow field. This shear layer, which has not been recognized by earlier investigators, impacts the stable operating range of the rotor. Simulation accuracy is dependent on the ability of the numerical code to resolve this layer. While numerical simulations of these flows are quite sophisticated, they are seldom verified through rigourous comparisons of numerical and measured data because these kinds of measurements are rare in the detail necessary to be useful in high-speed machines. In this paper we compare measured tip-clearance flow details (e.g., trajectory and radial extent) with corresponding data obtained from a numerical simulation. Laser-Doppler Velocimeter (LDV) measurements acquired in a transonic compressor rotor; NASA Rotor 35, are used. The tip clearance flow field of this transonic rotor is simulated using a Navier-Stokes turbomachinery solver that incorporates an advanced k-epsilon turbulence model derived for flows that are not in local equilibrium. A simple method is presented for determining when the wall-bounded shear layer is an important component of the tip clearance flow field. [S0889-504X(00)02504- 6]. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. USA, Vehicle Technol Ctr, Cleveland, OH 44135 USA. Iowa State Univ, Ames, IA 50011 USA. RP Van Zante, DE (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 23 TC 54 Z9 55 U1 1 U2 5 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD OCT PY 2000 VL 122 IS 4 BP 733 EP 742 DI 10.1115/1.1314609 PG 10 WC Engineering, Mechanical SC Engineering GA 404NM UT WOS:000167106700018 ER PT J AU Crucian, B Norman, J Brentz, J Pietrzyk, R Sams, C AF Crucian, B Norman, J Brentz, J Pietrzyk, R Sams, C TI Laboratory outreach: Student assessment of flow cytometer fluidics in zero gravity SO LABORATORY MEDICINE LA English DT Article AB Due to the the clinical utility of the flow cytometer, the National Aeronautics and Space Administration (NASA) is interested in the design of a space flight-compatible cytometer for use on long-duration space missions. Because fluid behavior is altered dramatically during space flight, it was deemed necessary to validate the principles of hydrodynamic focusing and laminar flow (cytometer fluidics) in a true microgravity environment. An experiment to validate these properties was conducted by 12 students from Sweetwater High School (Sweetwater, TX) participating in the NASA Reduced Gravity Student Flight Opportunity, Class of 2000. This program allows high school students to gain scientific experience by conducting an experiment on the NASA KC-135 zero gravity laboratory aircraft. The KC-135 creates actual zero-gravity conditions in 30-second intervals by flying a highly inclined parabolic flight path. The experiment was designed by their mentor in the program, the Johnson Space Center's flow cytometrist Brian Crucian, PhD, MT(ASCP). The students performed the experiment, with the mentor, onboard the NASA zero-gravity research aircraft in April 2000. C1 Wyle Labs, Cell Lab, Houston, TX USA. RP Sams, C (reprint author), NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Mail Code SD3, Houston, TX 77058 USA. NR 3 TC 2 Z9 2 U1 0 U2 1 PU AMER SOC CLIN PATHOLOGISTS PI CHICAGO PA 2100 W HARRISON ST, CHICAGO, IL 60612 USA SN 0007-5027 J9 LAB MED JI Lab. Med. PD OCT PY 2000 VL 31 IS 10 BP 569 EP 573 PG 5 WC Medical Laboratory Technology SC Medical Laboratory Technology GA 361NF UT WOS:000089728600019 PM 12442765 ER PT J AU DellaCorte, C AF DellaCorte, C TI Tribology ... The word that sticks us together 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 OCT PY 2000 VL 56 IS 10 BP 3 EP 3 PG 1 WC Engineering, Mechanical SC Engineering GA 362FH UT WOS:000089767600001 ER PT J AU Catalina, AV Mukherjee, S Stefanescu, DM AF Catalina, AV Mukherjee, S Stefanescu, DM TI A dynamic model for the interaction between a solid particle and an advancing solid/liquid interface SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID LIQUID INTERFACE; PHASE-TRANSITIONS; ENGULFMENT AB Most models that describe the interaction of an insoluble particle with an advancing solid-liquid interface are based on the assumption of steady state. However, as demonstrated by experimental work, the process does not reach Steady state until the particle is pushed for a while by the interface. In this work, a dynamic mathematical model was developed. The dynamic model demonstrates that this interaction is essentially non-steady state and that steady state eventually occurs only when solidification is conducted at subcritical velocities. The model was tested for three systems: aluminum-zirconia particles, succinonitrile-polystyrene particles, and biphenyl-glass particles. The calculated values for critical velocity of the pushing/engulfment transition were in the same range with the experimental ones. C1 NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35182 USA. Univ Alabama, Solificat Lab, Tuscaloosa, AL 35487 USA. RP Catalina, AV (reprint author), NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35182 USA. RI Stefanescu, Doru/G-8101-2012; Mukherjee, Sundeep/N-5247-2014; OI Stefanescu, Doru M./0000-0001-5544-8396 NR 29 TC 53 Z9 54 U1 0 U2 20 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 OCT PY 2000 VL 31 IS 10 BP 2559 EP 2568 DI 10.1007/s11661-000-0200-5 PG 10 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA 364WQ UT WOS:000089917400016 ER PT J AU Hyung, S Aller, LH Feibelman, WA Lee, WB de Koter, A AF Hyung, S Aller, LH Feibelman, WA Lee, WB de Koter, A TI The optical spectrum of the planetary nebula NGC 6543 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE ISM : abundances; planetary nebulae : general; planetary nebulae : individual : NGC 6543 ID CENTRAL STARS; EMISSION-LINES; MASS-LOSS; ULTRAVIOLET-SPECTRA; STELLAR WIND; GIANT HALO; NGC-6543; NGC-6826; VARIABILITY; EVOLUTION AB With the Hamilton echelle spectrograph at the Lick Observatory, emission-rich spectral lines of the planetary nebula NGC 6543 were secured in the wavelength range from 3550 to 10 100 Angstrom. We chose two bright regions, similar to 8 arcsec east and similar to 13 arcsec north of the central star, the physical conditions and chemical abundances of which may differ as a result of the different physical characteristics involving the mass ejection of different epochs. By combining Hamilton echelle observations with archive UV data secured with the International Ultraviolet Explorer (IUE), we obtain improved diagnostics and chemical compositions for the two observed regions. The diagnostic diagram gives the average value of T-e = 8000 similar to 8300 K, and the electron number density near N-e similar to 5000 cm(-3) for most ions, while some low-excitation lines indicate much higher temperatures, i.e. T-e similar to 10 000 K. With the construction of a photoionization model, we try to fit the observed spectra in a self-consistent way: thus, for most elements, we employ the same chemical abundances in the nebular shell; and we adopt an improved Sobolev approximation model atmosphere for the hydrogen-deficient Wolf-Rayet type central star. Within the observational errors, the chemical abundances do not seem to show any positional variation except for helium. The chemical abundances of NGC 6543 appear to be the same as in average planetary nebulae. The progenitor star may have been an object of one solar mass, most of the heavier elements of which were less plentiful than in the Sun. C1 Korea Astron Observ, Taejon 305348, South Korea. Univ Calif Los Angeles, Dept Phys & Astrophys, Los Angeles, CA 90095 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. RP Hyung, S (reprint author), Korea Astron Observ, 61-1 Whaam Dong, Taejon 305348, South Korea. NR 56 TC 27 Z9 27 U1 0 U2 1 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 PY 2000 VL 318 IS 1 BP 77 EP 91 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363VB UT WOS:000089857400014 ER PT J AU Roche, N Lowenthal, J Woodgate, B AF Roche, N Lowenthal, J Woodgate, B TI Ly alpha imaging of a very luminous z=2.3 starburst galaxy with WFPC2 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : evolution; galaxies : starburst; ultraviolet : galaxies ID STAR-FORMING GALAXIES; HIGH-REDSHIFT GALAXIES; EMISSION; SYSTEMS; SPECTROSCOPY; TELESCOPE; ABSORBER; FIELD; EVOLUTION; CLUSTER AB We investigate the Ly alpha and UV continuum morphology of one of the most luminous known Lyman alpha emitting galaxies (the 'Coup Fourre Galaxy'), associated with a z = 2.3 damped Ly alpha absorption system in the spectrum of the QSO PHL 957. The galaxy is observed with the Hubble Space Telescope Wide-Field Planetary Camera 2 (HST WFPC2), through a narrow filter (F410M) corresponding to rest-frame Ly alpha for a total exposure time of 41.2 ks, plus shorter exposures in F555W and F814W. In all three passbands, the galaxy is resolved into a close (similar to 0.35 arcsec) pair of two components, CFgA and CFgB, both of which are extended and elongated. The profile of CFgA is consistent with an exponential disk of similar scalelength in Ly alpha (r(exp) = 0.23 arcsec) and continuum (r(exp) = 0.20 arcsec), and no evidence of a central point source. In contrast, CFgB is closer to a bulge profile. We find that CFgA has by far the higher ratio of Ly alpha to continuum flux, and from the observed colours estimate rest-frame equivalent widths of W(Ly alpha) = 151 +/- 16 Angstrom for CFgA and 33 +/- 13 Angstrom for CFgB. From the F814W and F555W magnitudes we estimate the rest-frame blue-band absolute magnitudes (for H-0 = 50 km s(-1) Mpc(-1) and q(0) = 0.05) of -23.12 for CFgA and -23.24 for CFgB, significantly brighter than local galaxies of the same size. CFgA shows a remarkable 3.9 magnitudes of surface brightness enhancement relative to local spirals. This object appears to be at the upper limit of both the range of surface brightness evolution observed in z > 2 galaxies and the range of W(Ly alpha) in any star-forming galaxy. We speculate that its extreme surface brightness results from a very luminous starburst (similar to 200 M. yr(-1)), triggered by the merger of the two components, and the high W(Ly alpha) from a brief phase of the starburst in which most Ly alpha photons can escape, as predicted in the models of Tenorio-Tagle et al. (1999). We also investigated the F410M image of the QSO PHL 957. Subtraction of a normalized point-speed function leaves no significant residuals - the QSO is consistent with a pure point source and we do not detect either the host galaxy or the damped Ly alpha absorbing galaxy. We search for other galaxies with strong Ly alpha emission at z similar to 2.3-2.4, selecting these by colour (m(410) - V-555)(AB) < -0.2. Eight candidate Ly alpha sources, all fainter than the Coup Fourre Galaxy, are identified in our field. One is a point-source and may be an AGN; the others are of similar size to the Coup Fourre Galaxy but of lower surface brightness, knotty and asymmetric. They appear typical of Lyman break galaxies but with colours indicating W(Ly alpha) similar to 100 Angstrom. C1 Univ Massachusetts, Dept Phys & Astron, Amherst, MA 01003 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Roche, N (reprint author), Univ Massachusetts, Dept Phys & Astron, Box 34525, Amherst, MA 01003 USA. OI Roche, Nathan/0000-0003-1936-3058 NR 48 TC 11 Z9 11 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 1 PY 2000 VL 317 IS 4 BP 937 EP 951 DI 10.1046/j.1365-8711.2000.03718.x PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363UZ UT WOS:000089857200021 ER PT J AU Canuto, VM AF Canuto, VM TI Turbulence and laminar structures: can they co-exist? SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE turbulence ID SHEAR-DRIVEN FLOWS; CONVECTIVE BOUNDARY-LAYER; BOTTOM-UP DIFFUSION; DYNAMICAL MODEL; COMPRESSIBLE CONVECTION; TOP-DOWN; SIMULATIONS; TRANSPORT; CLOSURES; MOMENTS AB Schwarzschild first suggested that the laminar structures observed in the high Reynolds number Re = UL/nu approximate to O (10(12)) solar photosphere are the result of turbulence rather than a proof of its absence. He reasoned that, since turbulence generates large turbulent viscosities nu(t) much greater than nu, the 'effective' Reynolds number Re = UL/nu(t) approximate to O(1). Schwarzschild's argument is, however, incomplete, for it assumes that the entire role of the non-linear interactions is to 'enhance' viscosity. While this is not true in general, we present a proof of how and why it may occur, thus completing Schwarzschild's argument. We further discuss the fact that the same non-local turbulence models reproduce Large Eddy Simulation (LES) data for a variety of flows pertaining to astrophysics, geophysics and laboratory situations (in a fraction of the time). C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Appl Math & Phys, New York, NY 10027 USA. RP Canuto, VM (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM vcanuto@giss.nasa.gov NR 42 TC 7 Z9 7 U1 0 U2 3 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD OCT 1 PY 2000 VL 317 IS 4 BP 985 EP 988 DI 10.1046/j.1365-8711.2000.03786.x PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363UZ UT WOS:000089857200026 ER PT J AU Rao, PA Fuelberg, HE AF Rao, PA Fuelberg, HE TI An investigation of convection behind the Cape Canaveral sea-breeze front SO MONTHLY WEATHER REVIEW LA English DT Article ID NUMERICAL-SIMULATION; GRAVITY CURRENT; SOUTH FLORIDA; THUNDERSTORM OUTFLOW; INLAND PENETRATION; BOUNDARY-LAYER; PART I; AREA; DYNAMICS; FLOW AB A three-dimensional numerical simulation of land-water circulations near Cape Canaveral, Florida, is performed using the Advanced Regional Prediction System. The role of Kelvin-Helmholtz instability (KHI) in determining the time and location of convection behind the sea-breeze front is examined. The model configuration attempts to improve upon limitations of previous work (e.g., resolution, surface characteristics, initial state). It provides a detailed and realistic simulation of the desired features. The simulation exhibits a single precipitating storm that forms behind the sea-breeze front. This postfrontal storm develops when an outflow boundary intersects a deep layer of upward motion above the marine air. The region of ascent initially is the remnant of a cell that formed along the sea-breeze front, but before the cell decays, a portion of its upward motion is intensified and displaced. The modification of the ascent is a product of KHI that is occurring on top of the sea-breeze interface in the form of billows. The region of enhanced ascent then moves backward with the billow until the outflow boundary arrives. Thus. KHI can be critical in determining the location and time of storm development that occurs behind the Cape Canaveral sea-breeze front. C1 Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. RP Rao, PA (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Mesoscale Atmospher Proc Branch, Code 912, Greenbelt, MD 20771 USA. NR 55 TC 19 Z9 19 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD OCT PY 2000 VL 128 IS 10 BP 3437 EP 3458 DI 10.1175/1520-0493(2000)128<3437:AIOCBT>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 367AY UT WOS:000090040300005 ER PT J AU Refaat, TF Halama, GE DeYoung, RJ AF Refaat, TF Halama, GE DeYoung, RJ TI Comparison between super low ionization ratio and reach through avalanche photodiode structures SO OPTICAL ENGINEERING LA English DT Article DE water; remote sensing; atmospheric optics; lidar; photo-detectors; noise AB Avalanche photodiodes (APD) are solid state quantum detectors suitable for low level light detection in the visible and near infrared regions. These devices are commercially available from many manufacturers and are fabricated using several different solid state structures. In this paper a comparison between the well developed reach through structure (RTS) APD and the relatively newer super low ionization ratio, kappa, (SLIK) APD structure will be discussed. The comparison is based on the experimental characterization of two APDs with these structures. The characterization setup and experiments will be described which include the calibration of the APDs, temperature response, bias voltage response, and noise measurements including noise-equivalent-power and detectivity D*. For this comparison the selected RTS APD is the EG&G C30955E, currently used by the lidar atmospheric sensing experiment (LASE) instrument. The selected SLIK APD is the EG&G C30649E, which is proposed for LASE development. The characterization experiments where done in order to develop an advanced atmospheric water vapor differential absorption lidar detection system. (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)02710-0]. C1 Old Dominion Univ, Norfolk, VA 23508 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Refaat, TF (reprint author), Old Dominion Univ, KDH 231, Norfolk, VA 23508 USA. NR 11 TC 5 Z9 5 U1 0 U2 3 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD OCT PY 2000 VL 39 IS 10 BP 2642 EP 2650 DI 10.1117/1.1308925 PG 9 WC Optics SC Optics GA 365MA UT WOS:000089954000007 ER PT J AU Thompson, WT AF Thompson, WT TI Differential scrubbing in a microchannel-plate intensified CCD detector SO OPTICAL ENGINEERING LA English DT Article DE microchannel plates; extreme ultraviolet; detectors; space instrumentation; SOHO; Coronal Diagnostic Spectrometer/CDS ID PERFORMANCE; SOLAR AB One of the detector systems used for the Coronal Diagnostic Spectrometer instrument aboard the Solar and Heliospheric Observatory satellite is an intensified CCD camera. The intensifier section consists of a bare microchannel-plate detector proximity focused onto a phosphor, the light from which is then focused by a lens onto the CCD. Since the positions of the spectral lines are fixed on the detector, this leads to decreased efficiency in those areas of the detector where the strongest lines fall. The steps used to track this differential scrubbing of the detector in flight, and to remove these effects from the data, are described. Implications for future space missions are discussed. (C) 2000 Society of Photo-Optical instrumentation Engineers. [S0091-3286(00)03010-5]. C1 NASA, Emergent Informat Technol Inc, Div Space Sci, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Thompson, WT (reprint author), NASA, Emergent Informat Technol Inc, Div Space Sci, Goddard Space Flight Ctr, Code 682, Greenbelt, MD 20771 USA. RI Thompson, William/D-7376-2012 NR 6 TC 6 Z9 6 U1 0 U2 1 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD OCT PY 2000 VL 39 IS 10 BP 2651 EP 2659 DI 10.1117/1.1308486 PG 9 WC Optics SC Optics GA 365MA UT WOS:000089954000008 ER PT J AU Wernet, MP AF Wernet, MP TI Application of DPIV to study both steady state and transient turbomachinery flows SO OPTICS AND LASER TECHNOLOGY LA English DT Article ID PARTICLE IMAGE VELOCIMETRY; ROTOR; PIV AB Digital particle imaging velocimetry (DPIV) is a powerful measurement technique, which can be used as an alternative or complementary approach to laser doppler velocimetry (LDV) in a wide range of research applications. Thr instantaneous planar velocity measurements obtained with PIV make it an attractive technique for use in the study of the complex Row fields encountered in turbomachinery, The planar nature of the technique also significantly reduces the facility run time over point-based techniques. Techniques for optical access, light sheet delivery, CCD camera technology and particulate seeding are discussed. Results from the successful application of the PIV technique to both the blade passage region of a transonic axial compressor and the diffuser region of a high speed centrifugal compressor are presented. Both instantaneous and time-averaged Row fields were obtained. The averaged Row held measurements are used to estimate the Row turbulence intensity. The instantaneous velocity vector maps obtained during compressor surge provide previously unobtainable insight into the complex Row field characteristics occurring during short lived surge events. These Row field maps illustrate the true power of the DPIV technique. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Wernet, MP (reprint author), NASA, Glenn Res Ctr, MS-77-1,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 33 TC 23 Z9 25 U1 0 U2 5 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0030-3992 J9 OPT LASER TECHNOL JI Opt. Laser Technol. PD OCT-NOV PY 2000 VL 32 IS 7-8 BP 497 EP 525 DI 10.1016/S0030-3992(00)00090-6 PG 29 WC Optics; Physics, Applied SC Optics; Physics GA 399HP UT WOS:000166805800002 ER PT J AU Flesia, C Korb, CL Hirt, C AF Flesia, C Korb, CL Hirt, C TI Double-edge molecular measurement of lidar wind profiles at 355 nm SO OPTICS LETTERS LA English DT Article ID INCOHERENT DOPPLER LIDAR; MIDDLE ATMOSPHERE AB We built a direct-detection Doppler lidar based on the double-edge molecular technique and made the what we believe to be the first molecular-based wind measurements using the eye-safe 355-nm wavelength. Three etalon bandpasses are obtained with step etalons on a single pair of etalon plates. We eliminate long-term frequency drift of the laser and the capacitively stabilized etalon by locking the etalon to the laser frequency. We use a low-angle design to avoid polarization effects. Wind measurements of 1-2-m/s accuracy are obtained to 10-km altitude with 5 mJ of laser energy, a 750-s integration, and a 25-cm telescope, Good agreement is obtained between lidar and rawinsonde measurements. (C) 2000 Optical Society of America. C1 Univ Geneva, Appl Phys Grp, CH-1211 Geneva 4, Switzerland. NASA, Atmospheres Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Flesia, C (reprint author), Ctr Eccellenza Optron, Space Sect, Largo Enrico Fermi 6, I-50125 Florence, Italy. NR 11 TC 19 Z9 30 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD OCT 1 PY 2000 VL 25 IS 19 BP 1466 EP 1468 DI 10.1364/OL.25.001466 PG 3 WC Optics SC Optics GA 356HT UT WOS:000089438400020 PM 18066250 ER PT J AU Quattrochl, DA Luvall, JC Rickman, DL Estes, MG Laymon, CA Howell, BF AF Quattrochl, DA Luvall, JC Rickman, DL Estes, MG Laymon, CA Howell, BF TI A decision support information system for urban landscape management using thermal infrared data SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID REMOTE-SENSING DATA AB Efforts to use remote sensing data within the purview of an information support system, to assess urban thermal landscape characteristics as a means for developing more robust models of the urban heat-island (UHI) effect are described. We also present a rationale on how we have successfully translated the results from the study of urban thermal heating and cooling regimes as identified from remote sensing data, to decision-makers, planners, government officials, and the public at large in several U.S. cities to facilitate better understanding of how the UHI affects air quality. Additionally through the assessment of the spatial distribution of urban thermal landscape characteristics using remote sensing data, it is possible to develop strategies to mitigate the UHI that hopefulIy will, in turn, drive down ozone levels and improve overall urban air quality. Four U.S, cities have been the foci for intensive analyses as port of our studies: Atlanta, Georgia; Baton Rouge, Louisiana; Salt Lake City Utah; and Sacramento, California. The remote sensing data for each of these cities has been used to generate a number of products for use by "stakeholder" working groups to convey information on what the effects are of the UHI and what measures can be taken to mitigate them. In turn, these data products are used to both educate and inform policy-makers, planners, and the general public about what kinds of UHI mitigation strategies are available. C1 NASA, George C Marshall Space Flight Ctr, Dept Earth Sci, Huntsville, AL 35812 USA. Univ Space Res Assoc, Huntsville, AL 35805 USA. RP Quattrochl, DA (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Earth Sci, SD60, Huntsville, AL 35812 USA. OI Rickman, Doug/0000-0003-3409-2882 NR 33 TC 37 Z9 45 U1 1 U2 5 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 OCT PY 2000 VL 66 IS 10 BP 1195 EP 1207 PG 13 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 358FC UT WOS:000089546300007 ER PT J AU Cerf, NJ Iblisdir, S AF Cerf, NJ Iblisdir, S TI Optimal N-to-M cloning of conjugate quantum variables SO PHYSICAL REVIEW A LA English DT Article ID OPTIMAL UNIVERSAL; STATE ESTIMATION; PURE STATES AB The cloning of conjugate continuous quantum variables is analyzed based on the concept of Gaussian cloning machines, i.e., transformations that yield copies that are Gaussian mixtures centered on the state to be copied. The optimality of Gaussian cloning machines that transform N identical input states into M output states is investigated, and bounds on the fidelity of the process are derived via a connection with quantum estimation theory. In particular, the optimal N-to-M cloning fidelity fdr coherent states is found to be equal to MN/(MN+M-N). C1 Free Univ Brussels, Ecole Polytech, B-1050 Brussels, Belgium. CALTECH, Jet Prop Lab, Informat & Comp Technol Res Stn, Pasadena, CA 91109 USA. RP Cerf, NJ (reprint author), Free Univ Brussels, Ecole Polytech, CP 165, B-1050 Brussels, Belgium. NR 21 TC 79 Z9 82 U1 0 U2 2 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD OCT PY 2000 VL 62 IS 4 AR 040301 DI 10.1103/PhysRevA.62.040301 PG 3 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 360VU UT WOS:000089688700002 ER PT J AU Luo, LS AF Luo, LS TI Theory of the lattice Boltzmann method: Lattice Boltzmann models for nonideal gases SO PHYSICAL REVIEW E LA English DT Article ID NAVIER-STOKES EQUATION; REVISED ENSKOG EQUATION; IMMISCIBLE FLUIDS; KINETIC-THEORY; LIQUID-GAS; H-THEOREM; SIMULATION; FLOWS; HYDRODYNAMICS; DYNAMICS AB In this, paper a procedure for systematic a priori derivation of the lattice Boltzmann models for nonideal gases from the Enskog equation (the modified Boltzmann equation for dense gases) is presented. This treatment provides a unified theory of lattice Boltzmann models for nonideal gases. The lattice Boltzmann equation is systematically obtained by discretizing the Enskog equation in phase space and time. The lattice Boltzmann model derived in this paper is thermodynamically consistent up to the order of discretization error. Existing lattice Boltzmann models for nonideal gases are analyzed and compared in detail. An evaluation of these models is made in light of the general procedure to construct the lattice Boltzmann model for nonideal gases presented in this work. C1 NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. RP Luo, LS (reprint author), NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, MS 132C,3 W Reid St,Bldg 1152, Hampton, VA 23681 USA. RI Luo, Li-Shi/A-4561-2011 OI Luo, Li-Shi/0000-0003-1215-7892 NR 69 TC 226 Z9 235 U1 8 U2 39 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1063-651X J9 PHYS REV E JI Phys. Rev. E PD OCT PY 2000 VL 62 IS 4 BP 4982 EP 4996 DI 10.1103/PhysRevE.62.4982 PN A PG 15 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 365XY UT WOS:000089976800069 ER PT J AU Povitsky, A AF Povitsky, A TI Aeroacoustics of a stagnation flow near a rigid wall SO PHYSICS OF FLUIDS LA English DT Article ID FINITE-DIFFERENCE SCHEMES; COMPUTATIONAL AEROACOUSTICS; FORMULATION; ACOUSTICS; HARDIN; POPE AB Propagation of disturbances in a nonuniform mean flow is investigated by high-order numerical simulation for various initial conditions. Monopole and dipole acoustic, vortical and entropy pulses are embedded in an incompressible stagnation flow, which is taken as a prototype of a nonuniform low Mach number mean flow near a rigid wall at high angle of attack. Numerical results are discussed in terms of baroclinic generation of disturbance vorticity that appear to be a key process in energy transfer between a nonuniform mean flow and a propagating disturbance. These phenomena lead to amplification of sound waves originated from an acoustic pulse. Vorticity generation governs wave radiation of a near-wall entropy pulse and makes the radiated waves similar to those from a vortical dipole. Interaction of initial pulse vorticity with generated vorticity leads to various radiated wave patterns discussed here. (C) 2000 American Institute of Physics. [S1070- 6631(00)50810-1]. C1 NASA, ICASE, Langley Res Ctr, Hampton, VA 23681 USA. RP Povitsky, A (reprint author), NASA, ICASE, Langley Res Ctr, Mail Stop 132 C, Hampton, VA 23681 USA. NR 29 TC 5 Z9 5 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD OCT PY 2000 VL 12 IS 10 BP 2595 EP 2608 DI 10.1063/1.1288514 PG 14 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 351RB UT WOS:000089171000020 ER PT J AU Buti, B Velli, M Liewer, PC Goldstein, BE Hada, T AF Buti, B Velli, M Liewer, PC Goldstein, BE Hada, T TI Hybrid simulations of collapse of Alfvenic wave packets SO PHYSICS OF PLASMAS LA English DT Article ID COMET GIACOBINI-ZINNER; INHOMOGENEOUS PLASMAS; BETA PLASMA; SOLAR-WIND; SOLITONS; EVOLUTION; NONLINEARITY; PROPAGATION; TURBULENCE; EQUATION AB Nonlinear dynamics, of large-amplitude circularly polarized Alfvenic wave packets, is investigated using a one-dimensional hybrid model. Kinetic effects such as finite-Larmor radius and nonlinear Landau damping, which become significant for plasmas with beta similar to 1, are appropriately accounted for in these high-resolution hybrid simulations. Spatio-temporal evolution, of the left-hand polarized (LHP) wave packets, shows that they collapse because of the decreasing dispersive effects. However, singularities are arrested by the wave-particle interactions. At some critical time t(c), which depends on the plasma beta and the initial amplitude of the wave packet, we observe a turning point. At this turning point, the polarization changes from LHP to RHP (right-hand polarized). The wave packet then starts broadening due to increasing dispersion associated with the RHP. Implications of collapse of the magnetic structures are briefly discussed. (C) 2000 American Institute of Physics. [S1070-664X(00)02810-X]. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Dipartimento Astron & S Spazio, I-50125 Florence, Italy. Kyushu Univ, Interdisciplinary Grad Sch Engn Sci, Fukuoka 8168580, Japan. RP Buti, B (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM bbuti@jplsp2.jpl.nasa.gov RI U-ID, Kyushu/C-5291-2016 NR 36 TC 13 Z9 13 U1 0 U2 6 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 EI 1089-7674 J9 PHYS PLASMAS JI Phys. Plasmas PD OCT PY 2000 VL 7 IS 10 BP 3998 EP 4003 AR PII [S1070-664X(00)02810-X] DI 10.1063/1.1289890 PG 6 WC Physics, Fluids & Plasmas SC Physics GA 353QX UT WOS:000089287900024 ER PT J AU Huck, FO Fales, CL AF Huck, FO Fales, CL TI Optimal vision: Blurring and aliasing SO PHYSICS TODAY LA English DT Letter ID VISUAL COMMUNICATION C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Huck, FO (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 3 TC 0 Z9 0 U1 1 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD OCT PY 2000 VL 53 IS 10 BP 106 EP 106 DI 10.1063/1.1325214 PG 1 WC Physics, Multidisciplinary SC Physics GA 358FA UT WOS:000089546100029 ER PT J AU Treiman, AH Gleason, JD Bogard, DD AF Treiman, AH Gleason, JD Bogard, DD TI The SNC meteorites are from Mars SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT International Conference on Mars Exploration Program and Sample Return Missions CY FEB 02-05, 1999 CL PARIS, FRANCE ID NOBLE-GASES; MARTIAN ATMOSPHERE; TERRESTRIAL PLANETS; CARBON-DIOXIDE; ISOTOPE GEOCHEMISTRY; CHEMICAL-COMPOSITION; WEATHERING PRODUCTS; AQUEOUS ALTERATION; CORE FORMATION; EETA 79001 AB The 14 SNC meteorites are all igneous rocks, either basalts or basaltic cumulates. They are inferred to be from Mars, based on direct comparison with Martian materials and on consistency with inferences about Mars. Most telling is that the SNC meteorites contain traces of gas which is very similar in elemental and isotopic compositions to the modem Martian atmosphere as measured by Viking landers on Mars and spectroscopy from Earth. The Martian atmosphere appears to have a unique composition in the solar system, so its presence in the SNCs is accepted as strong direct evidence that they formed on Mars. Independent of this link, the SNC meteorites must be fi om a planet with a significant atmosphere because they contain several abundant gas components, one of which carries large isotopic fractionations characteristic of atmospheric processing. Further, the elemental compositions and oxidation state of the SNC meteorites are consistent with data from in situ analyses of Martian soils and rocks, and an quite distinct from compositions of other meteorites, rocks from the Earth, and rocks from the Moon. The range of formation ages for the SNC meteorites, 4.5-0.18 Ga, is consistent with the varied ages of the Martian surface (based on its cratering record) and inconsistent with surface ages on any other solar system body. The extreme chemical fractionations in the SNC meteorites suggest complex internal processes on a large planet, which is inconsistent with an asteroidal origin. Some SNCs were altered by aqueous solutions at < 0.7 Ga, consistent with the recent presence of liquid groundwater in Mars inferred independently from the geology of its surface. There seems little likelihood that the SNCs are not from Mars. If they were from another planetary body, it would have to be substantially identical to Mars as it now is understood. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Lunar & Planetary Inst, Houston, TX 77058 USA. Ecole Normale Super Lyon, UMR 8515, Lab Sci Terre, F-69364 Lyon 7, France. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Univ Michigan, Dept Geol Sci, 2534 CC Little Bldg,425 E Univ Ave, Ann Arbor, MI 48109 USA. EM treiman@lpi.jsc.nasa.gov; jdgleaso@umich.edu; donald.d.bogardl@jsc.nasa.gov NR 154 TC 85 Z9 89 U1 0 U2 9 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 OCT-DEC PY 2000 VL 48 IS 12-14 BP 1213 EP 1230 DI 10.1016/S0032-0633(00)00105-7 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 387RC UT WOS:000166134700008 ER PT J AU Lognonne, P Giardini, D Banerdt, B Gagnepain-Beyneix, J Mocquet, A Spohn, T Karczewski, JF Schibler, P Cacho, S Pike, WT Cavoit, C Desautez, A Favede, M Gabsi, T Simoulin, L Striebig, N Campillo, M Deschamp, A Hinderer, J Leveque, JJ Moatagner, JP Rivera, L Benz, W Breuer, D Defraigne, P Dehant, V Fujimura, A Mizutani, H Oberst, J AF Lognonne, P Giardini, D Banerdt, B Gagnepain-Beyneix, J Mocquet, A Spohn, T Karczewski, JF Schibler, P Cacho, S Pike, WT Cavoit, C Desautez, A Favede, M Gabsi, T Simoulin, L Striebig, N Campillo, M Deschamp, A Hinderer, J Leveque, JJ Moatagner, JP Rivera, L Benz, W Breuer, D Defraigne, P Dehant, V Fujimura, A Mizutani, H Oberst, J TI The NetLander very broad band seismometer SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT International Conference on Mars Exploration Program and Sample Return Missions CY FEB 02-05, 1999 CL PARIS, FRANCE ID FREE OSCILLATIONS; TERRESTRIAL PLANETS; METEOROID IMPACTS; MARTIAN MANTLE; LUNAR MANTLE; MARS; EXPLORATION; TOMOGRAPHY; SEISMOLOGY; EXCITATION AB The interior of Mars is today poorly known, in contrast to the Earth interior and, to a lesser extent, to the Moon interior, for which seismic data have been used for the determination of the interior structure. This is one of the strongest facts motivating the deployment on Mars of a network of very broad band seismometers, in the framework of the 2007 CNES-NASA joint mission. These seismometers will be carried by the Netlanders, a set of 4 landers developed by a European consortium, and are expected to land in mid-2008. Despite a low mass, the seismometers will have a sensitivity comparable to the present Very Broad Band Earth sensors, i.e. better than the past Apollo Lunar seismometers. They will record the full range of seismic and gravity signals, from the expected quakes induced by the thermoelastic cooling of the lithosphere, to the possible permanent excitation of the normal modes and tidal gravity perturbations. All these seismic signals will be able to constrain the structure of Mars ' mantle and its discontinuities, as well as the state and size of the Martian core, shortly after for the centennial of the discovery of the Earth core by Oldham (Quart. J. Geol, Sec. 62(1906) 356-475).(C) 2000 Elsevier Science Ltd. All rights reserved. C1 Inst Phys Globe Strasbourg Paris, Dept Etud Spatiales, F-94100 St Maur Des Fosses, France. Inst Phys Globe Strasbourg Paris, Dept Sismol, F-75252 Paris 05, France. ETH Honggerberg, Inst Geophys, CH-9093 Zurich, Switzerland. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Fac Sci & Tech, Lab Planetol & Geodynam, F-44322 Nantes, France. Inst Planetol, D-48149 Munster, Germany. Inst Phys Globe Strasbourg Paris, Dept Observ, F-94100 St Maur Des Fosses, France. Univ Garchy, Inst Natl Sci, Ctr Rech Geophys, Garching, Germany. IRIGM, Observ Grenoble, Lab Geophys Interne & Tectonphys, F-38041 Grenoble, France. UMR Geosci Azur, F-06560 Valbonne, France. Inst Phys Globe Strasbourg Strasbourg, F-67084 Strasbourg, France. Univ Bern, Inst Phys, CH-3012 Bern, Switzerland. Observ Royal Belgique, B-1180 Brussels, Belgium. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. DLR, Inst Planetary Explorat, D-12489 Berlin, Germany. RP Lognonne, P (reprint author), Inst Phys Globe Strasbourg Paris, Dept Etud Spatiales, 4 Ave Neptune, F-94100 St Maur Des Fosses, France. EM lognonne@ipgp.jussieu.fr RI Gagnepain-Beyneix, Jeannine/A-5738-2011; Giardini, Domenico/F-5406-2011; Lognonne, Philippe/F-8846-2010; Campillo, Michel/K-6231-2012; Deschamps, Anne/B-9433-2012 OI Deschamps, Anne/0000-0002-6209-9814 NR 62 TC 47 Z9 47 U1 0 U2 9 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 OCT-DEC PY 2000 VL 48 IS 12-14 BP 1289 EP 1302 DI 10.1016/S0032-0633(00)00110-0 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 387RC UT WOS:000166134700013 ER PT J AU Greeley, R Wilson, G Coquilla, R White, B Haberle, R AF Greeley, R Wilson, G Coquilla, R White, B Haberle, R TI Windblown dust on Mars: laboratory simulations of flux as a function of surface roughness SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT International Conference on Mars Exploration Program and Sample Return Missions CY FEB 02-05, 1999 CL PARIS, FRANCE ID MARTIAN SURFACE; PHYSICAL-PROPERTIES; PATHFINDER MISSION; GLOBAL SURVEYOR; AEOLIAN SAND; LANDING SITE; ATMOSPHERE; FEATURES; CAMERA; IMAGER AB Experiments were conducted to determine the flux of dust (particles < few microns in diameter) under Martian atmospheric conditions for surfaces of three aerodynamic roughnesses (z(0)). For smooth surfaces on Mars (z(0) = 0.00125 cm corresponding to 0.0125 cm on Mars) suspension threshold was not achieved at the highest velocities run (u(*) = 322 cm/s); for a moderately rough surface (z(0) = 0.010 cm corresponding to 0.10 cm on Mars), flux averaged 1.5 x 10(-7) g/cm(2)/s; for a rough surface (z(0) = 0.015 cm corresponding to 0.15 flux on Mars), flux averaged 5 x 10(-7) g/cm(2)/s. Although the results are preliminary, flux varied widely as a function of wind speed and roughness, suggesting that raising dust into suspension on Mars is complex. Nonetheless, using these results as a guide, 9000 Mt of dust could be raised into the atmosphere of Mars per second from only 5% of the surface. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Univ Calif Davis, Dept Aeronaut & Mech Engn, Davis, CA 95616 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Greeley, R (reprint author), Arizona State Univ, Dept Geol, Box 871404, Tempe, AZ 85287 USA. NR 42 TC 18 Z9 18 U1 0 U2 7 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 OCT-DEC PY 2000 VL 48 IS 12-14 BP 1349 EP 1355 DI 10.1016/S0032-0633(00)00115-X PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 387RC UT WOS:000166134700018 ER PT J AU Polkko, J Harri, AM Siili, T Angrilli, F Calcutt, S Crisp, D Larsen, S Pommereau, JP Stoppato, P Lehto, A Malique, C Tillman, JE AF Polkko, J Harri, AM Siili, T Angrilli, F Calcutt, S Crisp, D Larsen, S Pommereau, JP Stoppato, P Lehto, A Malique, C Tillman, JE TI The NetLander atmospheric instrument system (ATMIS): description and performance assessment SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT International Conference on Mars Exploration Program and Sample Return Missions CY FEB 02-05, 1999 CL PARIS, FRANCE ID THERMAL EMISSION SPECTROMETER; MARTIAN ATMOSPHERE; MARS-OBSERVER; NETWORK SCIENCE; DUST STORMS; SLOPE WINDS; SURFACE; LANDER; STATIONS; MISSION AB The pointwise meteorological observations of the Viking Lander and Mars Pathfinder as well as the orbital mapping and sounding performed by, e.g., Mariner 9, Viking Orbiters and the Mars Global Surveyor have given a good understanding of the basic behaviour of the Martian atmosphere. However, the more detailed characterisation of the Martian circulation patterns, boundary layer phenomena and climatological cycles requires deployment of meteorological surface networks. The European NetLander concept comprising four well-instrumented landers is being studied for launch in 2005 and operations spanning at least a Martian year in 2006-2008. The landers are to be deployed to areas in both Martian hemispheres from equatorial regions to low mid-latitudes. The NetLander atmospheric instrument system (ATMIS) on board each of the landers is designed to measure atmospheric vertical profiles of density, pressure and temperature during the descent onto the surface, as well as pressure, atmospheric and ground temperatures, wind, atmospheric optical thickness and humidity through a full Martian year, possibly beyond. The main operational objective of this meteorological experiment is to provide a regular time series of the meteorological parameters as well as accelerated measurement campaigns. Such a data set would substantially improve our understanding of the atmospheric structure, dynamics, climatological cycles, and the atmosphere-surface interactions. The ATMIS sensor systems and measurement approaches described here are based on solutions and technologies tested for similar observations on Mars-96, Mars Pathfinder, Huygens, and Mars Polar Lander. Although the number of observation sites only permits characterisation of some components of the general circulation, the NetLander ATMIS will more than double the number of in situ vertical profiles (only three profiles - two from Viking Landers and one from Mars Pathfinder - are currently available and as envisioned at the time of writing, none of the 2001 and 2003 landers ' payloads include entry phase measurements of pressure or temperature), perform the first in situ meteorological observations in the southern low- and mid-latitudes and provide the first simultaneous in situ multi-site observations of the local and general circulation patterns, in a variety of locations and terrains. As such, NetLander ATMIS will be the precursor of more comprehensive meteorological surface networks for future Mars exploration. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Finnish Meteorol Inst, Geophys Res Div, FIN-00101 Helsinki, Finland. Univ Padua, I-35131 Padua, Italy. Univ Oxford, Dept Atmosph Ocean & Planet Phys, Oxford OX1 3PU, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Riso Natl Lab, Wind Energy & Atmospher Phys Dept, DK-4000 Roskilde, Denmark. Serv Aeron, F-91471 Verrieres Le Buisson, France. Univ Washington, Dept Atmospher Sci, Seattle, WA 98195 USA. RP Polkko, J (reprint author), Finnish Meteorol Inst, Geophys Res Div, POB 503, FIN-00101 Helsinki, Finland. EM jouni.polkko@fmi.fi RI Harri, Ari-Matti/C-7142-2012; OI Harri, Ari-Matti/0000-0001-8541-2802; Calcutt, Simon/0000-0002-0102-3170 NR 37 TC 5 Z9 5 U1 0 U2 3 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 OCT-DEC PY 2000 VL 48 IS 12-14 BP 1407 EP 1420 DI 10.1016/S0032-0633(00)00119-7 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 387RC UT WOS:000166134700022 ER PT J AU Ortiz, RM Wade, CE Morey-Holton, E AF Ortiz, RM Wade, CE Morey-Holton, E TI Urinary excretion of LH and testosterone from male rats during exposure to increased gravity: Post-spaceflight and centrifugation SO PROCEEDINGS OF THE SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE LA English DT Article ID TESTICULAR FUNCTION; MICROGRAVITY; SERUM AB A dissociation between plasma luteinizing hormone (LH) and testosterone (T) appears to exist during exposure to altered gravity. The pulsatile nature of LH release and the diurnal variability of T secretion may mask or bias the effects of altered gravity on the pituitary-gonadal axis when analyzing plasma concentrations. Therefore, we examined the relationship between the excretion of urinary LH and T in male Sprague-Dawley rats during exposure to increased gravity upon return to Earth following a 14-day spaceflight (n = 6) and by 12 days of centrifugation at 2g (n = 8), Excreted LH and T were elevated on the first 3 days postflight, Excreted T was elevated between Days 1 and 8 of centrifugation; however, excreted LH was reduced on Days 2 and 3 compared with control animals. Excreted LH and T were significantly correlated (R = 0.731 and 0.706, respectively) in postspaceflight and centrifuged animals. Correlation curves had similar slopes (0.0213 and 0.023, respectively), but different y-intercepts (-1.43 and 3.32, respectively), The sustained increase in excreted T during centrifugation suggests that the pituitary-gonadal axis in postspaceflight animals may adapt quicker to increased gravity, The upward shift in the correlation curve exhibited by the centrifuged animals suggests that the sensitivity of LH-induced T release is increased in these animals. The previous dissociation between plasma LH and T during altered gravity was not observed in the present study in which excreted LH and T were measured. C1 Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. NASA, Div Life Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Ortiz, RM (reprint author), Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. NR 15 TC 12 Z9 12 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI MALDEN PA 350 MAIN ST, MALDEN, MA 02148 USA SN 0037-9727 J9 P SOC EXP BIOL MED JI Proc. Soc. Exp. Biol. Med. PD OCT PY 2000 VL 225 IS 1 BP 98 EP 102 DI 10.1046/j.1525-1373.2000.22512.x PG 5 WC Medicine, Research & Experimental SC Research & Experimental Medicine GA 359AV UT WOS:000089590100012 PM 10998204 ER PT J AU Cannizzo, JK Chen, W AF Cannizzo, JK Chen, W TI A hot inner disk during the quiescent state of soft X-ray transients? SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID DWARF-NOVA OUTBURSTS; ACTIVE GALACTIC NUCLEI; LIMIT-CYCLE MECHANISM; ACCRETION DISK; SPECTRAL EVOLUTION; COOLING FRONTS; BLACK-HOLES; MODEL; EVAPORATION; TRANSITION AB We examine a simple model to account for the observations during quiescence of the soft X-ray transients within the context of the standard accretion disk limit cycle. In our model the cooling front is not able to propagate completely to the inner edge of the accretion disk, so that a portion of the inner disk is always in the high state. The outer edge of this hot, ionized disk determines the rate of accretion and maximum temperature in the inner disk. We find that such a model is unable to account for the ROSAT observation by McClintock et al. of A0620-00 in quiescence: with r(crit) constrained to be similar to 10(9) cm so as to reproduce the observed level of X-ray flux (similar to 10(31) ergs s(-1), or (M) over dot similar to 10(11) g s(-1), for an assumed accretion efficiency of similar to 0.1), the inner effective temperature is about a factor of 10 too low (similar to 0.02 keV vs. similar to 0.2 keV). This confirms the estimates of Narayan, McClintock, & Yi. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Univ Space Res Assoc, Greenbelt, MD 20771 USA. NR 66 TC 0 Z9 0 U1 0 U2 1 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD OCT PY 2000 VL 112 IS 776 BP 1330 EP 1340 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363BX UT WOS:000089815000007 ER PT J AU Fixsen, DJ Offenberg, JD Hanisch, RJ Mather, JC Nieto-Santisteban, MA Sengupta, R Stockman, HS AF Fixsen, DJ Offenberg, JD Hanisch, RJ Mather, JC Nieto-Santisteban, MA Sengupta, R Stockman, HS TI Cosmic-ray rejection and readout efficiency for large-area arrays SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID NOISE; NGST AB We present an algorithm to optimally process uniformly sampled array image data obtained with a nondestructive readout. The algorithm discards full wells, removes cosmic-ray (particle) hits and other glitches, and makes a nearly optimum estimate of the signal on each pixel. The algorithm also compresses the data. The computer requirements are modest, and the results are robust. The results are shown and compared to results of Fowler-sampled and -processed data. Nonideal detector performance may require some additional code, but this is not expected to cost much processing time. Known types of detector faults are addressed. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 9 TC 33 Z9 33 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD OCT PY 2000 VL 112 IS 776 BP 1350 EP 1359 DI 10.1086/316626 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363BX UT WOS:000089815000009 ER PT J AU Stern, D AF Stern, D TI Probing the dark ages: Observations of the high-redshift universe SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article C1 Univ Calif Berkeley, Berkeley, CA 94720 USA. RP Stern, D (reprint author), CALTECH, Jet Prop Lab, Mail Stop 169-327, Pasadena, CA 91109 USA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD OCT PY 2000 VL 112 IS 776 BP 1411 EP 1411 DI 10.1086/316629 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 363BX UT WOS:000089815000013 ER PT J AU Stewart, IS Sauber, J Rose, J AF Stewart, IS Sauber, J Rose, J TI Glacio-seismotectonics: ice sheets, crustal deformation and seismicity SO QUATERNARY SCIENCE REVIEWS LA English DT Review ID EARTHQUAKE HAZARD ASSESSMENT; LAKE-ONTARIO REGION; SEA-LEVEL CHANGE; ISOSTATIC-ADJUSTMENT; MANTLE VISCOSITY; EASTERN CANADA; NEW-ZEALAND; FOCAL MECHANISMS; BARENTS SEA; FENNOSCANDIAN SEISMICITY AB The last decade has witnessed a significant growth in our understanding of the past and continuing effects of ice sheets and glaciers on contemporary crustal deformation and seismicity. This growth has been driven largely by the emergence of postglacial rebound models (PGM) constrained by new field observations that incorporate increasingly realistic rheological, mechanical, and glacial parameters. In this paper, we highlight some of these recent held-based investigations and new PGMs, and examine their implications for understanding crustal deformation and seismicity during glaciation and following deglaciation. The emerging glacial rebound models outlined in the paper support the view that both tectonic stresses and glacial rebound stresses are needed to explain the distribution and style of contemporary earthquake activity in former glaciated shields of eastern Canada and Fennoscandia. However, many of these models neglect important parameters, such as topography, lateral variations in lithospheric strength and tectonic strain built up during glaciation. In glaciated mountainous terrains, glacial erosion may directly modulate tectonic deformation by resetting the orogenic topography and thereby providing an additional compensatory uplift mechanism. Such effects are likely to be important both in tectonically active orogens and in the mountainous regions of glaciated shields. In general, the short-term response to ice fluctuations is similar to the Earth's response to fluctuations in water reservoirs with the subsequent increase or decrease in seismicity which depends on the pre-existing stress state. When the ice fluctuations occur on the spatial scale, and magnitude, of the Late Pleistocene glaciation and deglaciation, however, the viscoelastic response of the Earth (especially the mantle) causes significant changes in crustal deformation and earthquake activity that is spatially extensive and temporally complex. The regions of greatest ice thickness and the regions marginal to the Late Pleistocene ice sheets indicate the most dramatic evidence of earthquake faulting. The mantle response to these large ice mass fluctuations and the change in mass between the oceans and land caused, and continues to cause, measureable crustal deformation at hundreds of kilometres from the ice margins. For both tectonically active and cratonic regions, palaeoseismic investigations of Late Pleistocene and Holocene faults are an important tool in evaluating earthquake hazard. The predicted response of the Earth over this time, however, is very dependent on the model assumed. For most regions, far more carefully designed field observations are needed to constrain the existing rheological and ice models. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Brunel Univ, Neotecton Res Ctr, Dept Geog & Earth Sci, Uxbridge UB8 3PH, Middx, England. NASA, Goddard Space Flight Ctr, Terr Phys Lab, Geodynam Branch, Greenbelt, MD 20771 USA. Univ London, Royal Holloway & Bedford New Coll, Dept Geog, Egham TW20 0EX, Surrey, England. RP Stewart, IS (reprint author), Brunel Univ, Neotecton Res Ctr, Dept Geog & Earth Sci, Uxbridge UB8 3PH, Middx, England. EM iain.stewart@brunel.ac.uk RI Sauber, Jeanne/D-7684-2012; Stewart, Iain/H-5044-2012 NR 183 TC 136 Z9 137 U1 8 U2 26 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0277-3791 J9 QUATERNARY SCI REV JI Quat. Sci. Rev. PD OCT PY 2000 VL 19 IS 14-15 BP 1367 EP 1389 DI 10.1016/S0277-3791(00)00094-9 PG 23 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 361CA UT WOS:000089703100001 ER PT J AU Meigs, A Sauber, J AF Meigs, A Sauber, J TI Southern Alaska as an example of the long-term consequences of mountain building under the influence of glaciers SO QUATERNARY SCIENCE REVIEWS LA English DT Review ID NORTH-AMERICAN PLATE; YUKON-TERRITORY; RESPONSE-TIME; HIMALAYAN ARC; MASS-BALANCE; EROSION; TECTONICS; HISTORY; PLEISTOCENE; OROGENS AB Southern Alaska is a continent-scale region of ongoing crustal deformation within the Pacific-North American plate boundary zone. Glaciers and glacial erosion have dictated patterns of denudation in the orogen over the last similar to 5 Myr. The orogen comprises three discrete topographic domains from south to north, respectively: (1) the Chugach/St. Elias Range; (2) the Wrangell Mountains; and (3) the eastern Alaska Range. Although present deformation is distributed across the orogen, much of the shortening and uplift are concentrated in the Chugach/St. Elias Range. A systematic increase in topographic wavelength of the range from east to west reflects east-to-west increases in the width of a shallowly dipping segment of the plate interface, separation of major upper plate structures, and a decrease in the obliquity of plate motion relative to the plate boundary. Mean elevation decays exponentially from similar to 2500 to similar to 1100 m from east to west, respectively. Topographic control on the present and past distribution of glaciers is indicated by close correspondence along the range between mean elevation and the modern equilibrium line altitude of glaciers (ELA) and differences in the modern ELA, mean annual precipitation and temperature across the range between the windward, southern and leeward, northern flanks. Net, range-scale erosion is the sum of (1) primary bedrock erosion by glaciers and (2) erosion in areas of the landscape that are ice-marginal and are deglaciated at glacial minima. Oscillations between glacial and interglacial climates controls ice height and distribution, which, in turn, modulates the locus and mode of erosion in the landscape. Mean topography and the mean position of the ELA are coupled because of the competition between rock uplift, which tends to raise the ELA, and enhanced orographic precipitation accompanying mountain building, which tends to lower the ELA. Mean topography is controlled both by the 60 degrees latitude and maritime setting of active deformation and by the feedback between shortening and uplift, glacial erosion, and orographic effects on climate accompanying mountain building. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Oregon State Univ, Dept Geosci, Corvallis, OR 97331 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD USA. RP Meigs, A (reprint author), Oregon State Univ, Dept Geosci, 104 Wilkinson Hall, Corvallis, OR 97331 USA. RI Meigs, Andrew/A-6230-2011; Sauber, Jeanne/D-7684-2012 NR 92 TC 61 Z9 61 U1 0 U2 7 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0277-3791 J9 QUATERNARY SCI REV JI Quat. Sci. Rev. PD OCT PY 2000 VL 19 IS 14-15 BP 1543 EP 1562 DI 10.1016/S0277-3791(00)00077-9 PG 20 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA 361CA UT WOS:000089703100012 ER PT J AU Privette, JL Asner, GP Conel, J Huemmrich, KF Olson, R Rango, A Rahman, AF Thome, K Walter-Shea, EA AF Privette, JL Asner, GP Conel, J Huemmrich, KF Olson, R Rango, A Rahman, AF Thome, K Walter-Shea, EA TI The EOS prototype validation exercise (PROVE) at Jornada: Overview and lessons learned SO REMOTE SENSING OF ENVIRONMENT LA English DT Article AB Tho forth Observing System (EOS) instrument teams must validate the operational products they produce from the Terra spacecraft data. As a pilot for future validation activities, four EOS teams (MODIS, MISR, ASTER, and Landsat-7) and community experts conducted an Il-dar field campaign in May 1997 near Las Cruces, NM. The goals of the Prototype Validation Exercise (PROVE) included (1) gaining experience in the collection and use of field data for EOS product validation; (2) developing coordination, measurement, and data-archiving protocols; and (3) compiling a synoptic land and atmospheric data set for testing algorithms. PROVE was held at the USDA-Agricultural Research Service's (ARS) Jornada Experimental Range, an expansive desert plateau hosting a complex mosaic of grasses and shrubs. Most macroscopic variables affecting the radiation environment were measured with ground air-borne (including AVIRIS and laser altimeter), and space-borne sensors (including AVHRR, Landsat TM SPOT, POLDER, and GOES). The Oak Ridge Distributed Active Archive Center (DAAC) then used campaign data sets to prototype Mercury, its Internet-based data harvesting and distribution system. This article provides general information about PROVE and assesses the progress made toward the campaign goat. Primary successes included the rapid campaign formulation and execution, measurement protocol development, and the significant collection, reduction, and sharing of data among participants. However, the PROVE data were used primarily for arid-la nd research and model validation rather than for validating satellite products, and the data were slow; to reach the DAAC and hence public domain. The lessons learned included: (1) validation campaigns can be rapidly organized and implemented if there are focused objectives and on-site facilities and expertise; (2) data needs, organization, storage, and access issues must be addressed at the onset of campaign planning; and (3) the end-to-end data collection, release, and publication environment may need to be readdressed by program managers, funding agencies, and journal editors if rapid and comprehensive validation of operational satellite products is to occur Published by Elsevier Science Inc. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Colorado, Dept Geol Sci, Boulder, CO 80309 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Univ Maryland, Dept Geog, Baltimore, MD 21201 USA. Oak Ridge Natl Lab, Oak Ridge, TN USA. USDA ARS, Beltsville Agr Res Ctr, Beltsville, MD 20705 USA. Calif State Univ Los Angeles, Dept Geog, Los Angeles, CA 90032 USA. Univ Arizona, Ctr Opt Sci, Tucson, AZ 85721 USA. Univ Nebraska, Dept Nat Resource Sci, Lincoln, NE 68583 USA. RP Privette, JL (reprint author), NASA, Goddard Space Flight Ctr, Code 923, Greenbelt, MD 20771 USA. RI Privette, Jeffrey/G-7807-2011; Thome, Kurtis/D-7251-2012; Asner, Gregory/G-9268-2013 OI Privette, Jeffrey/0000-0001-8267-9894; Asner, Gregory/0000-0001-7893-6421 NR 25 TC 29 Z9 31 U1 2 U2 9 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 OCT PY 2000 VL 74 IS 1 BP 1 EP 12 DI 10.1016/S0034-4257(00)00117-6 PG 12 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 356NA UT WOS:000089448300001 ER PT J AU White, MA Asner, GP Nemani, RR Privette, JL Running, SW AF White, MA Asner, GP Nemani, RR Privette, JL Running, SW TI Measuring fractional cover and leaf area index in arid ecosystems: Digital camera, radiation transmittance, and laser altimetry methods SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SPECTRAL VEGETATION INDEXES; PLANT CANOPY ANALYZER; LI-COR LAI-2000; PINE STANDS; RAPID ESTIMATION; NEW-MEXICO; FORESTS; DESERTIFICATION; SENSITIVITY; RANGELAND AB Field measurement of shrubland ecological properties is important for both site monitoring and validation of remote sensing information. During the May 1997 NASA Earth Observing System Jornada Prototype Validation Exercise, we calculated plot-level plant area index leaf area index, total fractional cover, and green fractional cover with data from four instruments: (1) a Dycam Agricultural Digital Camera (ADC), (2) a LI-COR LAI-2000 plant canopy analyser, (3) a Decagon sunfleck Ceptometer, and (4) a laser altimeter. Estimates from the LAI-2000 and Ceptometer were very similar (plant area index 0.3, leaf area index 0.22, total fractional cover 0.19, green fractional cover 0.14), while the ADC produced values 5% to 10% higher. Laser altimeter values, depending on the height cutoff used to establish total fractional cover were either higher or lower than the other instruments' values: a 10-cm cutoff produced values similar to 80% higher, while a 20-cm cutoff produced values similar to 30% lower The LAI-2000 and Ceptometer are designed to operate in hamogenons canopies, not the sparse and irregular vegetation found at Jornada. Thus, these instruments were primarily useful for relative within-site plant area index monitoring. Calculation of some parameters required destructive sampling, a relatively slow and labor-intensive activity that limits spatial and temporal applicability. Validation/monitoring campaigns therefore should be guided by consideration of the amount of time and resources required to obtain measurements of the desired variables. Our results suggest that the ADC is both efficient and accurate for long-term or large-scale monitoring of arid ecosystems. (C) Elsevier Science Inc., 2000. C1 Univ Montana, Sch Forestry, NTSG, Missoula, MT 59812 USA. Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. RP White, MA (reprint author), Univ Montana, Sch Forestry, NTSG, Missoula, MT 59812 USA. RI Privette, Jeffrey/G-7807-2011; Asner, Gregory/G-9268-2013; OI Privette, Jeffrey/0000-0001-8267-9894; Asner, Gregory/0000-0001-7893-6421; White, Michael/0000-0002-0238-8913 NR 43 TC 115 Z9 143 U1 2 U2 34 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 OCT PY 2000 VL 74 IS 1 BP 45 EP 57 DI 10.1016/S0034-4257(00)00119-X PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 356NA UT WOS:000089448300004 ER PT J AU Asner, GP Wessman, CA Bateson, CA Privette, JL AF Asner, GP Wessman, CA Bateson, CA Privette, JL TI Impact of tissue, canopy, and landscape factors on the hyperspectral reflectance variability of arid ecosystems SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID VEGETATION CANOPIES; OPTICAL-PROPERTIES; CONIFER NEEDLES; CLIMATE; EXPANSION; AUSTRALIA; DESERTS; IMAGERY; LEAVES; INDEX AB Changes in vegetation distribution and condition commonly occur in arid ecosystems clue to land use and climate variability. Most arid land remote sensing efforts have focused on detecting vegetation change using spectral: indices, such as the normalized vegetation index, with limited success. Less attention has focused on using the continuous shortwave spectrum (0.4 mu m to 2.5 mu m) for studying vegetation in arid environments. Using field measurements and a photon transport model, we quantified the absolute and relative importance of tissue, canopy, and landscape factors that drive pixel-level shortwave reflectance variation along a land-cover gradient in the Chihuahuan Desert, New Mexico. Green foliage, wood standing litter, and bare soil had distinctive spectral properties, often via specific, narrow absorption features and through overall differences in the shape of their shortwave spect ra. While the amount of each plant material varied significantly along the land-cover gradient, foliar optical properties remained relatively stable, supporting the hypothesis that resource variation (e.g., water and nutrients) is more strongly resolved at the scale of whole plant canopies (e.g., via allocation and production) than at the leaf level. Significant variation in vegetation type and condition along the gradient resulted in only subtle changes in pixel-level reflectance variability, which could be determined in, high spectral resolution Airborne Visible and Infrared Imaging Spectrometer data. Most important, the relative impact of tissue, canopy and landscape factors on pixel-level reflectance shifted with plant composition and phenology. Mie compared the ability to resolve these vegetation and soil factors using Airborne Visible and Infrared Imaging Spectrometer; Moderate Resolution Imaging Spectrometer, and Landsat Thematic Mapper optical channels and found that feu; factors could be accounted for unless most of the spectral range was adequately sampled. (C) Elsevier Science Inc., 2000. C1 Univ Colorado, Dept Geol Sci & Environm Studies, Boulder, CO 80309 USA. Univ Colorado, Dept EPO Biol, Boulder, CO 80309 USA. Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Asner, GP (reprint author), Univ Colorado, Dept Geol Sci, CB 399, Boulder, CO 80309 USA. RI Privette, Jeffrey/G-7807-2011; Asner, Gregory/G-9268-2013 OI Privette, Jeffrey/0000-0001-8267-9894; Asner, Gregory/0000-0001-7893-6421 NR 55 TC 106 Z9 107 U1 2 U2 20 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 OCT PY 2000 VL 74 IS 1 BP 69 EP 84 DI 10.1016/S0034-4257(00)00124-3 PG 16 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 356NA UT WOS:000089448300006 ER PT J AU Qin, WH Gerstl, SAW AF Qin, WH Gerstl, SAW TI 3-D scene modeling of semidesert vegetation cover and its radiation regime SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID RADIOSITY METHOD; REFLECTANCE AB To explore the potential of multiangle remote sensing for estimating biophysical or ecological parameters over a variety of landscapes, a modeling tool that is capable of handling three-dimensional (3-D) heterogeneous structures, deriving ecological parameters from the vegetation structure, and effectively working on different scene scales is very desirable. A 3-D scene modeling approach for these purposes is presented in this paper. This 3-D model fulfills its goal by taking advantage of radiosity theory and computer graphics techniques. It consists of two major modules: a modified extended L-systems (MELS) method to gene-rate a 3-D realistic scene and a radiosity-graphics combined method (RGM) to calculate the radiation regime based on the 3-D structures rendered with MELS. The 3-D simulation tool is then evaluated using field measurements of both plant structure and spectra collected during the NASA Earth Observing Satellite Prototype Validation Exercise Jornada field campaign near Las Cruces, NM. The modeled scene reflectance is compared with measurements from three platforms (ground tower, and satellite) at various scales (from the size of individual shrub component to satellite pixels of kilometers). The agreement with measured reflectances is excellent at all sampling scales tested. As an example of the model's application, we use the model output to examine the validity of a linear mixture scheme over the Jornada semidesert scene. The result shows that the larger the sampling size (at least larger than the size of the shrub component), the better the hypothesis is satisfied because of the unique structure of the Jornada scene: dense plant clumps (shrub component) sparsely scattered on a predominantly bare soil background. A range of possible applications of this 3-D scene model is highlighted. and further work needed for 3-D modeling is also discussed. (C) Elsevier Science Inc., 2000. C1 NASA, Goddard Space Flight Ctr, Raytheon, ITSS, Greenbelt, MD 20771 USA. Univ Calif Los Alamos Natl Lab, NIS, RS, Los Alamos, NM USA. RP Qin, WH (reprint author), NASA, Goddard Space Flight Ctr, Raytheon, ITSS, Code 916, Greenbelt, MD 20771 USA. NR 20 TC 73 Z9 96 U1 2 U2 7 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 OCT PY 2000 VL 74 IS 1 BP 145 EP 162 DI 10.1016/S0034-4257(00)00129-2 PG 18 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 356NA UT WOS:000089448300011 ER PT J AU Srinivasan, RS Gerth, WA Powell, MR AF Srinivasan, RS Gerth, WA Powell, MR TI A mathematical model of diffusion-limited gas bubble dynamics in tissue with varying diffusion region thickness SO RESPIRATION PHYSIOLOGY LA English DT Article DE diffusion, gas bubble; disease, decompression sickness; gas, diffusion, bubble; model, gas bubble AB The three-region model of gas bubble dynamics consists of a bubble and a well-stirred tissue region with an intervening unperfused diffusion region previously assumed to have constant thickness and uniform gas diffusivity. As a result, the diffusion region gas content remains unchanged as its volume increases with bubble growth, causing dissolved gas in the region to violate Henry's law. Earlier work also neglected the relationship between the varying diffusion region volume and the fixed total tissue volume. The present work corrects these theoretical inconsistencies by postulating a difference in gas diffusivity between an infinitesimally thin layer at the bubble surface and the remainder of the diffusion region, thus allowing both thickness and gas content of the diffusion region to vary during bubble evolution. The corrected model can yield bubble lifetimes considerably longer than those yielded by earlier three-region models, and meets a need for theoretically consistent but relatively simple bubble dynamics models for use in studies of decompression sickness (DCS) in human subjects. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Wyle Labs, Houston, TX 77058 USA. USN, Expt Diving Unit, Panama City, FL 32407 USA. NASA, Lyndon B Johnson Space Ctr, Environm Physiol Lab, Houston, TX 77058 USA. RP Srinivasan, RS (reprint author), Wyle Labs, 1290 Hercules Dr,Suite 120, Houston, TX 77058 USA. NR 8 TC 18 Z9 18 U1 2 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0034-5687 J9 RESP PHYSIOL JI Respir. Physiol. PD OCT PY 2000 VL 123 IS 1-2 BP 153 EP 164 DI 10.1016/S0034-5687(00)00173-0 PG 12 WC Physiology; Respiratory System SC Physiology; Respiratory System GA 357DA UT WOS:000089482200014 PM 10996196 ER PT J AU Foster, JE AF Foster, JE TI Transverse magnetic field propellant isolator SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB An alternative high voltage propellant isolator for electric propulsion and ground-based ion source applications has been designed and tested. This design employs a transverse magnetic field that increases the breakdown voltage. The design can greatly enhance the operating range of laboratory propellant isolators used for high voltage applications. [S0034-6748(00)04510-X]. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Foster, JE (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 15 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 2000 VL 71 IS 10 BP 3684 EP 3688 DI 10.1063/1.1290509 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 358JG UT WOS:000089554500013 ER PT J AU Gubarev, M Ciszak, E Ponomarev, I Gibson, W Joy, M AF Gubarev, M Ciszak, E Ponomarev, I Gibson, W Joy, M TI A compact x-ray system for macromolecular crystallography SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID OPTICS; DIFFRACTION AB We describe the design and performance of a high flux x-ray system for a macromolecular crystallography that combines a microfocus x-ray generator (40 mu m full width at half maximum spot size at a power level of 46.5 W) and a collimating polycapillary optic. The Cu K alpha x-ray flux produced by this optimized system through a 500 mu m diam orifice is 7.0 times greater than the x-ray flux previously reported by Gubarev [M. Gubarev , J. Appl. Crystallogr. 33, 882 (2000)]. The x-ray flux from the microfocus system is also 2.6 times higher than that produced by a rotating anode generator equipped with a graded multilayer monochromator (green optic, Osmic, Inc. CMF24-48-Cu6) and 40% less than that produced by a rotating anode generator with the newest design of graded multilayer monochromator (blue optic, Osmic, Inc. CMF12-38-Cu6). Both rotating anode generators operate at a power level of 5000 W, dissipating more than 100 times the power of our microfocus x-ray system. Diffraction data collected from small test crystals are of high quality. For example, 42 540 reflections collected at ambient temperature from a lysozyme crystal yielded R-sym=5.0% for data extending to 1.70 Angstrom, and 4.8% for the complete set of data to 1.85 Angstrom. The amplitudes of the observed reflections were used to calculate difference electron density maps that revealed positions of structurally important ions and water molecules in the crystal of lysozyme using the phases calculated from the protein model. (C) 2000 American Institute of Physics. [S0034- 6748(00)01211-9]. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Natl Res Council, Huntsville, AL 35812 USA. Univ Space Res Assoc, Huntsville, AL 35805 USA. Xray Opt Syst Inc, Albany, NY 12203 USA. SUNY Albany, Ctr Xray Opt, Albany, NY 12222 USA. RP Ciszak, E (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 12 TC 8 Z9 8 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD OCT PY 2000 VL 71 IS 10 BP 3900 EP 3904 DI 10.1063/1.1311937 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 358JG UT WOS:000089554500048 ER PT J AU Macintyre, IG Prufert-Bebout, L Reid, RP AF Macintyre, IG Prufert-Bebout, L Reid, RP TI The role of endolithic cyanobacteria in the formation of lithified laminae in Bahamian stromatolites SO SEDIMENTOLOGY LA English DT Article DE endolithic cyanobacteria; lithification; micritization; stromatolites ID MODERN MARINE STROMATOLITES; MICROBIAL MATS; SUBTIDAL STROMATOLITES; EXUMA-CAYS; PRESERVATION; REEF AB The microboring activity of endolithic cyanobacteria plays a major role in the formation of the dominant lithified laminae in modern marine stromatolites in the Exuma Gays, Bahamas. These stromatolites are composed primarily of fine-grained carbonate sand that is trapped and bound by the filamentous cyanobacteria Schizothrix sp.. Periodic introduction of coccoid endolithic cyanobacteria Solentia sp. during hiatuses in stromatolite growth associated with very low rates of sedimentation results in the formation of lithified horizons, 200-1000 mum thick. These layers consist of micritized grains that are welded together at point contacts. The micritization is caused by extensive microboring and carbonate precipitation within boreholes concurrent with endolithic activity. Grain welding occurs when boreholes cross from one grain to another at point contacts. Thus, microboring destroys original grain textures but, at the same time, plays a constructional role in stromatolite growth by forming lithified layers of welded grains; These lateral bands of fused carbonate grains help to stabilize and preserve the stromatolite deposits. C1 Natl Museum Nat Hist, Dept Paleobiol, Smithsonian Inst, Washington, DC 20560 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Miami, FL 33149 USA. RP Macintyre, IG (reprint author), Natl Museum Nat Hist, Dept Paleobiol, Smithsonian Inst, NHB-125, Washington, DC 20560 USA. NR 26 TC 88 Z9 92 U1 1 U2 7 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0037-0746 J9 SEDIMENTOLOGY JI Sedimentology PD OCT PY 2000 VL 47 IS 5 BP 915 EP 921 DI 10.1046/j.1365-3091.2000.00327.x PG 7 WC Geology SC Geology GA 371CQ UT WOS:000165160700001 ER PT J AU Kraemer, SK AF Kraemer, SK TI NASA and the space industry. SO TECHNOLOGY AND CULTURE LA English DT Book Review C1 NASA Headquarters, Washington, DC USA. RP Kraemer, SK (reprint author), NASA Headquarters, Washington, DC USA. NR 1 TC 0 Z9 0 U1 1 U2 1 PU JOHNS HOPKINS UNIV PRESS PI BALTIMORE PA JOURNALS PUBLISHING DIVISION, 2715 NORTH CHARLES ST, BALTIMORE, MD 21218-4319 USA SN 0040-165X J9 TECHNOL CULT JI Technol. Cult. PD OCT PY 2000 VL 41 IS 4 BP 849 EP 851 PG 3 WC History & Philosophy Of Science SC History & Philosophy of Science GA 372PL UT WOS:000165242300048 ER PT J AU Tippett, MK Cohn, SE Todling, R Marchesin, D AF Tippett, MK Cohn, SE Todling, R Marchesin, D TI Low-dimensional representation of error covariance SO TELLUS SERIES A-DYNAMIC METEOROLOGY AND OCEANOGRAPHY LA English DT Article ID ATMOSPHERIC DATA ASSIMILATION; MAXIMUM-LIKELIHOOD-ESTIMATION; ALGEBRAIC LYAPUNOV EQUATION; SINGULAR VECTORS; VARIATIONAL ASSIMILATION; BAROCLINIC WAVES; ENSEMBLE PREDICTION; KALMAN FILTER; FORECAST; SYSTEM AB Ensemble and reduced-rank approaches to prediction and assimilation rely on low-dimensional approximations of the estimation error covariances. Here stability properties of the forecast/analysis cycle for linear, time-independent systems are used to identify factors that cause the steady-state analysis error covariance to admit a low-dimensional representation. A useful measure of forecast/analysis cycle stability is the bound matrix, a function of the dynamics, observation operator and assimilation method. Upper and lower estimates for the steady-state analysis error covariance matrix eigenvalues are derived from the bound matrix. The estimates generalize to time-dependent systems. If much of the steady-state analysis error variance is due to a few dominant modes, the leading eigenvectors of the bound matrix approximate those of the steady-state analysis error covariance matrix. The analytical results are illustrated in two numerical examples where the Kalman filter is carried to steady state. The first example uses the dynamics of a generalized advection equation exhibiting non-modal transient growth. Failure to observe growing modes leads to increased steady-state analysis error variances. Leading eigenvectors of the steady-state analysis error covariance matrix are well approximated by leading eigenvectors of the bound matrix. The second example uses the dynamics of a damped baroclinic wave model. The leading eigenvectors of a lowest-order approximation of the bound matrix are shown to approximate well the leading eigenvectors of the steady-state analysis error covariance matrix. C1 Ctr Previsao Tempo & Estudos Climat, Cachoeira Paulista, SP, Brazil. NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Gen Sci Corp, SAIC,DAO, Greenbelt, MD 20771 USA. Inst Matemat Pura & Aplicado, Rio De Janeiro, Brazil. RP Tippett, MK (reprint author), Columbia Univ, Lamont Doherty Earth Observ, Int Res Inst Climate Predict, POB 1000-61 Route 9W, Palisades, NY 10964 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 47 TC 14 Z9 14 U1 0 U2 1 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6495 J9 TELLUS A JI Tellus Ser. A-Dyn. Meteorol. Oceanol. PD OCT PY 2000 VL 52 IS 5 BP 533 EP 553 DI 10.1034/j.1600-0870.2000.00849.x PG 21 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA 362MU UT WOS:000089782400006 ER PT J AU Jones, WR Pepper, SV Wheeler, DR Jansen, MJ Nguyen, Q Schroer, A AF Jones, WR Pepper, SV Wheeler, DR Jansen, MJ Nguyen, Q Schroer, A TI The effect of stress and TiC coated balls on lifetime of a perfluoropolyalkylether using a vacuum rolling contact tribometer SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT ASME/STLE Tribology Conference CY OCT 01-04, 2000 CL SEATTLE, WASHINGTON SP Soc Tribologists & Lubricat Engineers, ASME DE aerospace tribology; ball bearings; perfluoropolyalkylether ID BEARING AB A vacuum spiral orbit tribometer (SOT) was used to determine the relative lifetimes of a branched perfluoropolyalkylether (PFPAE) on 440C stainless steel. The effect of varying the mean Hertzian stress (0.75, 1.0, 1.5 and 2.0 GPa) and the use of TiC coated balls on lubricant lifetime was studied. Other conditions included: similar to 100 rpm, similar to 50 mu g of lubricant, an initial vacuum level of < 1.3 x 10(-6) Pa (< 1.0 x 10(-8) Torr), and room temperature (similar to 23 degrees C). Increasing the mean Hertzian stress from 0.75 to 2.0 GPa results in an exponential decrease in lubricant lifetime for both material combinations. However, substituting a TiC ball for the 440C ball quadrupled lifetime at low stress levels (0.75 and 1.0 GPa) and doubled life at higher stresses (1.5 and 2.0 GPa). The reduced reactivity of the TiC surface with the PFPAE lubricant is considered to be the reason for this enhancement. Decreasing lifetime with increasing stress levels correlated well with energy dissipation calculations. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. AYT Corp, Brookpk, OH USA. Ctr Suisse Elect & Microtech SA, CSEM, Neuchatel, Switzerland. RP Jones, WR (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 17 TC 10 Z9 10 U1 1 U2 1 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 1040-2004 J9 TRIBOL T JI Tribol. Trans. PD OCT PY 2000 VL 43 IS 4 BP 685 EP 688 DI 10.1080/10402000008982397 PG 4 WC Engineering, Mechanical SC Engineering GA 357AA UT WOS:000089475300018 ER PT J AU Ball, DW Zehe, MJ Morales, W AF Ball, DW Zehe, MJ Morales, W TI Experimental and calculational studies of the interactions of BF3 with fluoroethers SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT 53rd Annual Meeting of the Society-of-Tribologists-and-Lubrication-Engineers CY MAY 17-21, 1998 CL DETROIT, MICHIGAN SP Soc Tribologists & Lubricat Engineers DE infrared spectroscopy; chemical attack; fluorocarbons ID DECOMPOSITION; DEGRADATION; SURFACES; ALUMINA; ETHER; AL2O3 AB BF3 was co-condensed with (C2H5)(2)O, (CF3CH2)(2)O, and (C2F5)(2)O in excess argon at 15 K. Infrared spectra of the matrices showed a definite Lewis acid-base interaction between BF3 and diethyl ether; a weak but definite interaction with bis(2,2,2,-trifluorodiethyl)ether, and no observable interaction with perfluorodiethyl ether. Molecular orbital (MO) calculations complemented the experimental observations by revealing that fluorine atoms on the ethers decreased electron localization about the oxygen atom. Thus, the experimental data and MO calculations indicated a clear trend between strength of interaction with BF, and the degree of ether F substitution. The implications of the results for commercial perfluoro ether lubricant/metal oxide surface interactions are discussed. C1 Cleveland State Univ, Dept Chem, Cleveland, OH 44115 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Ball, DW (reprint author), Cleveland State Univ, Dept Chem, Cleveland, OH 44115 USA. RI Young, Nigel/B-5472-2010 NR 22 TC 3 Z9 3 U1 0 U2 0 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 1040-2004 J9 TRIBOL T JI Tribol. Trans. PD OCT PY 2000 VL 43 IS 4 BP 767 EP 773 DI 10.1080/10402000008982406 PG 7 WC Engineering, Mechanical SC Engineering GA 357AA UT WOS:000089475300027 ER PT J AU Dellacorte, C Lukaszewicz, V Valco, MJ Radil, KC Heshmat, H AF Dellacorte, C Lukaszewicz, V Valco, MJ Radil, KC Heshmat, H TI Performance and durability of high temperature foil air bearings for oil-free turbomachinery SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT 55th Annual Meeting of the Society-of-Tribologists-and-Lubrication-Engineers CY MAY 07-11, 2000 CL NASHVILLE, TENNESSEE SP Soc Tribologists & Lubricat Engineers DE foil air bearings; load capcity; bearing torque; friction ID COMPOSITE AB The performance and durability of advanced, high temperature foil air bearings are evaluated under a wide range (10 to 50 kPa) of loads at temperatures from 25 degrees to 650 degrees C. The bearings are made from uncoated nickel based superalloy foils. The foil surface experiences sliding contact with the shaft during initial start/stop operation. To reduce friction and wear, the solid lubricant coating, PS304, is applied to the shaft by plasma spraying. PS304 is a NiCr based Cr2O3 coating with silver and barium fluoride/calcium fluoride solid lubricant additions. The results show that the bearings provide lives well in excess of 30,000 cycles under all of the conditions tested. Several bearings exhibited lives in excess of 100,000 cycles. Wear is a linear function of the bearing load. The excellent performance measured in this study suggests that these bearings and the PS304 coating are well suited for advanced high temperature, oil-free turbomachinery applications. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Akima Corp, Brook Pk, OH USA. USA, Res Lab, Glenn Res Ctr, Cleveland, OH USA. Mohawk Innovat Technol Inc, Albany, NY USA. RP Dellacorte, C (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 18 TC 25 Z9 27 U1 1 U2 6 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 1040-2004 J9 TRIBOL T JI Tribol. Trans. PD OCT PY 2000 VL 43 IS 4 BP 774 EP 780 DI 10.1080/10402000008982407 PG 7 WC Engineering, Mechanical SC Engineering GA 357AA UT WOS:000089475300028 ER PT J AU Dellacorte, C Valco, MJ AF Dellacorte, C Valco, MJ TI Load capacity estimation of foil air journal bearings for oil-free turbomachinery applications SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT ASME/STLE Tribology Conference CY OCT 01-04, 2000 CL SEATTLE, WASHINGTON SP Soc Tribologists & Lubricat Engineers, ASME DE foil air bearings; load capacity; turbomachinery; gas bearings AB This paper introduces a simple "Rule of Thumb" (ROT) method to estimate the load capacity of foil air journal bearing, which are self-acting compliant-surface hydrodynamic bearings being considered for Oil-Free turbomachinery applications such as gas turbine engines; The ROT is based on first principles and data available in the literature and it relates bearing load capacity to the bearing size and speed through an empirically based load capacity coefficient, D. It is shown that load capacity is a linear function of bearing surface velocity and bearing projected area. Furthermore, it was found that the load capacity coefficient, D, is related to the design features of the bearing compliant members and operating conditions (speed and ambient temperature). Early bearing designs with basic or "first generation" compliant support elements have relatively low load capacity. More advanced bearings, in which the compliance of the support structure is tailored, have load capacities up to five times those of simpler designs. The ROT enables simplified load capacity estimation for foil air journal bearings and can guide development of new Oil-Free turbomachinery systems. C1 NASA, Glenn Res Ctr, USA, Res Lab, Cleveland, OH 44135 USA. RP Dellacorte, C (reprint author), NASA, Glenn Res Ctr, USA, Res Lab, Cleveland, OH 44135 USA. NR 31 TC 112 Z9 119 U1 1 U2 7 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 1040-2004 J9 TRIBOL T JI Tribol. Trans. PD OCT PY 2000 VL 43 IS 4 BP 795 EP 801 DI 10.1080/10402000008982410 PG 7 WC Engineering, Mechanical SC Engineering GA 357AA UT WOS:000089475300031 ER PT J AU Avant, OL Jones, JA Beck, H Hunt, C Straub, M AF Avant, OL Jones, JA Beck, H Hunt, C Straub, M TI New method to improve treatment outcomes for radical prostatectomy SO UROLOGY LA English DT Article ID BLADDER NECK PRESERVATION; RETROPUBIC PROSTATECTOMY; URINARY CONTINENCE; APICAL DISSECTION; CANCER; IMPACT; ANASTOMOSIS; RESECTION AB Modifications in radical retropubic prostatectomy that use the deep dorsal vein ligator and either anterior urethropexy or puboprostatic ligament preservation were developed to reduce blood loss and improve continence results. Use of the deep dorsal vein ligator to secure the deep dorsal vein complex also improves visualization of the urethra for transection and the neurovascular bundle for nerve sparing and thereby may assist in laparoscopic radical retropubic prostatectomy. UROLOGY 56: 658-662, 2000, (C) 2000, Elsevier Science Inc. C1 Texas Tech Univ, Hlth Sci Ctr, Dept Surg, Div Urol, Lubbock, TX 79430 USA. NASA, JSC Space & Life Sci Directorate, Div Med Sci, Med Operat Branch, Houston, TX USA. Baylor Coll Med, Dept Urol, Houston, TX 77030 USA. RP Avant, OL (reprint author), Lubbock Urol Clin, 4503 89th St, Lubbock, TX 79424 USA. NR 26 TC 18 Z9 19 U1 1 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0090-4295 J9 UROLOGY JI UROLOGY PD OCT PY 2000 VL 56 IS 4 BP 658 EP 662 DI 10.1016/S0090-4295(00)00701-9 PG 5 WC Urology & Nephrology SC Urology & Nephrology GA 359AK UT WOS:000089589200027 PM 11018627 ER PT J AU Whitehead, J Papanastassiou, DA Spray, JG Grieve, RAF Wasserburg, GJ AF Whitehead, J Papanastassiou, DA Spray, JG Grieve, RAF Wasserburg, GJ TI Late Eocene impact ejecta: geochemical and isotopic connections with the Popigai impact structure SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article DE microtektites; Eocene; impacts; Popigay Structure; ejecta; isotopes ID CLINOPYROXENE-BEARING SPHERULES; NORTH-AMERICAN MICROTEKTITES; MISTASTIN-LAKE-CRATER; RB-SR SYSTEMATICS; TEKTITE MATERIAL; STREWN FIELD; NEW-JERSEY; BARBADOS; AGE; ND AB Late Eocene microtektites and crystal-bearing microkrystites extracted from DSDP and ODP cores from the Atlantic, Pacific, and Indian oceans have been analyzed to address their provenance. A new analysis of Nd and Sr isotopic compositions confirms previous work and the assignment of the uppermost microtektite layer to the North American tektites, which are associated with the 35.5 Ma, 85 km diameter Chesapeake impact structure of Virginia, USA. Extensive major element and Nd and Sr isotopic analyses of the microkrystites from the lowermost layer were obtained. The melanocratic microkrystites from Sites 216 and 462 in the Indian and Pacific oceans possess major element chemistries, Sr and Nd isotopic signatures and Sm-Nd, T-CHUR, model ages similar to those of tagamite melt rocks in the Popigai impact structure. They also possess Rb-Sr, TUR, model ages that are younger than the tagamite T-CHUR ages by up to similar to 1 Ga, which require a process, as yet undefined, of Rb/Sr enrichment. These melanocratic microkrystites are consistent with a provenance from the 35.7 Ma, 100 km diameter Popigai impact structure of Siberia, Russia, while ruling out other contemporaneous structures as a source. Melanocratic microkrystites from other sites and leucocratic microkrystites from all sites possess a wide range of isotopic compositions (epsilon(Nd-143) values of -16 to -27.7 and epsilon(Sr-87) values of 4.1-354.0), making the association with Popigai tagamites less clear. These microkrystites may have been derived by the melting of target rocks of mixed compo sition, which were ejected without homogenization. Dark glass and felsic inclusions extracted from Popigai tagamites possess epsilon(Nd-143) and epsilon(Sr-87) values of -26.7 to -27.8 and 374.7 and 432.4, respectively, and T-CHUR and TUR model ages of 1640-1870 Ma and 240-1830 Ma, respectively, which require the preservation of initially present heterogeneity in the source materials. The leucocratic microkrystites possess diverse isotopic compositions that may reflect the melting of supra-basement sedimentary rocks from Popigai, or early basement melts that were ejected prior to homogenization of the Popigai tagamites. The ejection of melt rocks with chemistries consistent with a basement provenance, rather than the surface similar to 1 km of sedimentary cover rocks, atypically indicates a non-surficial source to some of the ejecta. Microkrystites from two adjacent biozones possess statistically indistinguishable major element compositions, suggesting they have a single source. The occurrence of microkrystites derived from a single impact event, but in different biozones, can be explained by: (1) diachronous biozone boundaries; (2) post-accumulation sedimentary reworking; or (3) erroneous biozonation. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ New Brunswick, Dept Geol, Planetary & Space Sci Ctr, Fredericton, NB E3B 5A3, Canada. CALTECH, Div Geol & Planetary Sci, Lunat Asylum, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. Nat Resources Canada, Earth Sci Sector, Ottawa, ON K1A 0E8, Canada. RP Whitehead, J (reprint author), Univ New Brunswick, Dept Geol, Planetary & Space Sci Ctr, Fredericton, NB E3B 5A3, Canada. RI Spray, John/J-7504-2013 NR 47 TC 49 Z9 51 U1 0 U2 7 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 SEP 30 PY 2000 VL 181 IS 4 BP 473 EP 487 DI 10.1016/S0012-821X(00)00225-9 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 358GY UT WOS:000089551300001 ER PT J AU Mavriplis, DJ AF Mavriplis, DJ TI Adaptive meshing techniques for viscous flow calculations on mixed element unstructured meshes SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE adaptive meshing; multigrid solver; unstructured meshes ID EULER EQUATIONS; REFINEMENT; SCHEME AB An adaptive refinement strategy based on hierarchical element subdivision is formulated and implemented for meshes containing arbitrary mixtures of tetrahedra, hexahedra, prisms, and pyramids. Special attention is given to keeping memory overheads as low as possible. This procedure is coupled with an algebraic multigrid flow solver, which operates on mixed element meshes. Inviscid flows, as well as viscous flows, are computed on adaptively refined tetrahedral, hexahedral, and hybrid meshes. The efficiency of the method is demonstrated by generating an adapted hexahedral mesh containing 3 million vertices on a relatively inexpensive workstation. Copyright (C) 2000 John Wiley & Sons, Ltd. C1 NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. RP Mavriplis, DJ (reprint author), NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Mail Stop 403, Hampton, VA 23681 USA. NR 21 TC 30 Z9 31 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD SEP 30 PY 2000 VL 34 IS 2 BP 93 EP 111 DI 10.1002/1097-0363(20000930)34:2<93::AID-FLD48>3.0.CO;2-3 PG 19 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA 360JZ UT WOS:000089665300001 ER PT J AU Wilson, AW Howe, JM Garg, A Noebe, RD AF Wilson, AW Howe, JM Garg, A Noebe, RD TI TEM study of beta ' precipitation in Ni-Al-Ti alloys SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article DE intermetallic; precipitation; solubility; L2(1) phase; energy-dispersive X-ray analysis ID TEMPERATURE TENSILE DUCTILITY; SINGLE-CRYSTALS; BEHAVIOR; SYSTEM AB The precipitation of beta'-Ni2AlTi has been investigated in NiAl-Ti alloys as a function of Ti concentration and aging treatment. The precipitation mechanism for beta' is nucleation and growth in these alloys for the given heat treatments, The solubility of Ti has been measured using quantitative energy-dispersive X-ray spectroscopy. These measurements agree with the results and trends of other researchers, and show the solubility of Ti decreases with temperature to 2.7 at.% at 1000 K. Comparisons to other studies of beta' precipitation in the Ni-Al-Ti system are made and conditions under which possible mechanisms can occur are discussed. (C) 2000 Elsevier Science S.A. All rights reserved. C1 Univ Virginia, Dept Mat Sci & Engn, Charlottesville, VA 22903 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Univ Virginia, Dept Mat Sci & Engn, Charlottesville, VA 22903 USA. NR 36 TC 7 Z9 7 U1 0 U2 7 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 EI 1873-4936 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD SEP 30 PY 2000 VL 289 IS 1-2 BP 162 EP 171 DI 10.1016/S0921-5093(00)00841-8 PG 10 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 342CU UT WOS:000088628300019 ER PT J AU Leamy, MJ Gottlieb, O AF Leamy, MJ Gottlieb, O TI Internal resonances in whirling strings involving longitudinal dynamics and material non-linearities SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID FORCED VIBRATION; NONPLANAR; MOTION AB Internal resonance mechanisms between near-commensurate longitudinal and transverse modes of a taut spatial string are identified and studied using an asymptotic method, and the influence of material non-linearities on the resulting solutions is considered. Geometrical non-linearities couple longitudinal motions to in-plane and out-of-plane transverse motions, resulting in resonant and non-resonant interactions between linearly orthogonal string modes. Past studies have included only transverse modes in the description of string motions and have predicted periodic, quasi-periodic, and chaotic whirling motions arising from the geometrical non-linearities. This study considers further the inclusion of longitudinal motions and a non-linear material law, which are both appropriate for the study of rubber-like strings. An asymptotic analysis captures the aforementioned whirling motions, as well as a new class of whirling motions with significant longitudinal content. Periodic, quasi-periodic, and aperiodic (likely chaotic) responses are included among these motions. Their existence, hardening-softening characterization, and stability are found to be highly dependent on the magnitude of the material non-linearities. (C) 2000 Academic Press. C1 Technion Israel Inst Technol, Fac Mech Engn, IL-32000 Haifa, Israel. RP Leamy, MJ (reprint author), NASA, Langley Res Ctr, Mail Stop 201,11W Taylor St,Bldg 1146,Room 116, Hampton, VA 23601 USA. NR 16 TC 12 Z9 12 U1 0 U2 2 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD SEP 28 PY 2000 VL 236 IS 4 BP 683 EP 703 DI 10.1006/jsvi.2000.3039 PG 21 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 356NB UT WOS:000089448400008 ER PT J AU Michelsen, HA Irion, FW Manney, GL Toon, GC Gunson, MR AF Michelsen, HA Irion, FW Manney, GL Toon, GC Gunson, MR TI Features and trends in Atmospheric Trace Molecule Spectroscopy (ATMOS) version 3 stratospheric water vapor and methane measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPICAL LOWER STRATOSPHERE; TOTAL HYDROGEN BUDGET; UARS HALOE DATA; POLAR VORTEX; ATMOS/ATLAS-3 MEASUREMENTS; ANTARCTIC STRATOSPHERE; DEHYDRATION MECHANISM; FOUNTAIN HYPOTHESIS; SEASONAL-VARIATIONS; AGE SPECTRA AB Mixing ratios of water vapor entering the stratosphere are inferred from Atmospheric Trace Molecule Spectroscopy (ATMOS) measurements to be 3.28 ppm in 1985, 3.53 ppm in 1992, 3.67 ppm in 1993, and 3.65 ppm in 1994, yielding an average increase of 0.041 +/- 0.007 (1 sigma) ppm/yr or 1.2 +/- 0.2%/yr between 1985 and 1994. Strong evidence for a seasonal cycle in water vapor is apparent below 45 km in the tropics, and ascent rates derived from these tropical profiles are comparable to previous estimates. An enhancement in the sum [H2O] + 2[CH4] apparent between 45 and 60 km in the tropics appears to be consistent with remnants of a seasonal cycle in [H2O]. C1 Sandia Natl Labs, Combust Res Facil, Livermore, CA 94551 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sandia Natl Labs, Combust Res Facil, MS 9055,POB 969, Livermore, CA 94551 USA. EM hamiche@ca.sandia.gov; fwi@caesar.jpl.nasa.gov; manney@mls.jpl.nasa.gov; toon@mark4sun.jpl.nasa.gov; mrg@caesar.jpl.nasa.gov NR 86 TC 35 Z9 36 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 SEP 27 PY 2000 VL 105 IS D18 BP 22713 EP 22724 DI 10.1029/2000JD900336 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 359EF UT WOS:000089598000004 ER PT J AU Hall, TM AF Hall, TM TI Path histories and timescales in stratospheric transport: Analysis of an idealized model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPICAL STRATOSPHERE; CARBON-DIOXIDE; AGE SPECTRA; AIR; TROPOSPHERE; CO2; SF6 AB Mean age and the age spectrum, transport diagnostics independent of photochemistry, have been put to good use diagnosing stratospheric circulation and evaluating models. These diagnostics reveal how long air took to reach a stratospheric location from the troposphere, but they provide no direct information about where the air traveled en route. I define a complement to the age spectrum to explore how stratospheric transport timescales are related to path histories. Just as one constructs the age spectrum by distributing components of an air parcel according to transit time since last tropospheric contact, one can distribute the components according to the maximum height achieved en route to the parcel. Combining the age spectrum and the "maximum path height" distribution, one has a "joint distribution" of transit time and maximum path height. These ideas are illustrated with an idealized model of stratospheric transport, as well as a general circulation model. Transport features in the idealized model that strongly affect mean age affect the distribution of maximum path heights relatively weakly, especially in midlatitudes. The mass fraction of an air parcel at r that passed above some specified height z above r is strongly constrained by the mass continuity of stratospheric regions and is only more weakly affected by the circulation. This represents a limit on the relationship between mean age and trace gases of predominantly upper stratospheric photochemistry. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM thall@giss.nasa.gov NR 31 TC 14 Z9 14 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 SEP 27 PY 2000 VL 105 IS D18 BP 22811 EP 22823 DI 10.1029/2000JD900329 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 359EF UT WOS:000089598000011 ER PT J AU Platnick, S AF Platnick, S TI Vertical photon transport in cloud remote sensing problems SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SOLAR-RADIATION MEASUREMENTS; EFFECTIVE PARTICLE RADIUS; MARINE STRATOCUMULUS; MICROPHYSICAL PROPERTIES; AIRCRAFT OBSERVATIONS; OPTICAL-THICKNESS; FIRE-II; ALBEDO; RETRIEVAL; AEROSOLS AB Photon transport in plane-parallel, vertically inhomogeneous clouds is investigated and applied to cloud remote sensing techniques that use solar reflectance or transmittance measurements for retrieving droplet effective radius. Transport is couched in terms of weighting functions which approximate the relative contribution of individual layers to the overall retrieval. Two vertical weightings are investigated, including one based on the average number of scatterings encountered by reflected and transmitted photons in any given layer. A simpler vertical weighting, based on the maximum penetration of reflected photons, proves useful for solar reflectance measurements. These weighting functions are highly dependent on droplet absorption and solar/viewing geometry. A superposition technique, using adding/doubling radiative transfer procedures, is used to accurately determine both weightings, avoiding time-consuming Monte Carlo methods. Effective radius retrievals from modeled vertically structured liquid water clouds are then made using the standard near-infrared bands and compared with size estimates based on the proposed weighting functions. Agreement between the two methods is generally within several tenths of a micrometer, much better than expected retrieval accuracy. Though the emphasis is on photon transport in clouds, the derived weightings can be applied to any multiple-scattering plane-parallel radiative transfer problem, including arbitrary combinations of cloud, aerosol, and gas layers. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. RP NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. EM platnick@climate.gsfc.nasa.gov RI Platnick, Steven/J-9982-2014 OI Platnick, Steven/0000-0003-3964-3567 NR 47 TC 143 Z9 144 U1 3 U2 13 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 SEP 27 PY 2000 VL 105 IS D18 BP 22919 EP 22935 DI 10.1029/2000JD900333 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 359EF UT WOS:000089598000018 ER PT J AU Cantrell, JH Yost, WT AF Cantrell, JH Yost, WT TI Determination of precipitate nucleation and growth rates from ultrasonic harmonic generation SO APPLIED PHYSICS LETTERS LA English DT Article AB An analytical model based on precipitate-dislocation interactions is presented that predicts a decrease in ultrasonic harmonic generation during the nucleation of precipitates and an increase during precipitate growth up to the point of precipitate-matrix coherency loss. The opposing effects allow independent, indirect assessments of nucleation and growth rates from a curve fit of the model equation to experimental data. Application to the assessment of S-' precipitation during the artificial aging of AA2024 yields a constant nucleation rate of 5.4x10(15) m(-3) s(-1) and a growth rate increasing as the 1.2 power of time in the range 72-432 min during heat treatment at 463 K. [S0003-6951(00)00639-2]. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Cantrell, JH (reprint author), NASA, Langley Res Ctr, Mail Stop 231, Hampton, VA 23681 USA. NR 8 TC 38 Z9 41 U1 0 U2 4 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD SEP 25 PY 2000 VL 77 IS 13 BP 1952 EP 1954 DI 10.1063/1.1311951 PG 3 WC Physics, Applied SC Physics GA 354RW UT WOS:000089344300011 ER PT J AU Greeley, R Figueredo, PH Williams, DA Chuang, FC Klemaszewski, JE Kadel, SD Prockter, LM Pappalardo, RT Head, JW Collins, GC Spaun, NA Sullivan, RJ Moore, JM Senske, DA Tufts, BR Johnson, TV Belton, MJS Tanaka, KL AF Greeley, R Figueredo, PH Williams, DA Chuang, FC Klemaszewski, JE Kadel, SD Prockter, LM Pappalardo, RT Head, JW Collins, GC Spaun, NA Sullivan, RJ Moore, JM Senske, DA Tufts, BR Johnson, TV Belton, MJS Tanaka, KL TI Geologic mapping of Europa SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CONAMARA CHAOS REGION; GALILEAN SATELLITES; SUBSURFACE OCEAN; ICE SHELL; JUPITER; SURFACE; SPECTROMETER; SEPARATION; FEATURES; FAULT AB Galileo data enable the major geological units, structures, and surface features to be identified on Europa. These include five primary units (plains, chaos, band, ridge, and crater materials) and their subunits, along with various tectonic structures such as faults. Plains units are the most widespread. Ridged plains material spans a wide range of geological ages, including the oldest recognizable features on Europa, and appears to represent a style of tectonic resurfacing, rather than cryovolcanism. Smooth plains material typically embays other terrains and units, possibly as a type of fluid emplacement, and is among the youngest material units observed. At global scales, plains are typically mapped as undifferentiated plains material, although in some areas differences can be discerned in the near infrared which might be related to differences in ice grain size. Chaos material is composed of plains and other preexisting materials that have been severely disrupted by inferred internal activity; chaos is characterized by blocks of icy material set in a hummocky matrix. Band material is arrayed in linear, curvilinear, wedge-shaped, or cuspate zones with contrasting albedo and surface textures with respect to the surrounding terrain. Bilateral symmetry observed in some bands and the relationships with the surrounding units suggest that band material forms by the lithosphere fracturing, spreading apart, and infilling with material derived from the subsurface. Ridge material is mapped as a unit on local and some regional maps but shown with symbols at global scales. Ridge material includes single ridges, doubler ridges, and ridge complexes. Ridge materials are considered to represent tectonic processes, possibly accompanied by the extrusion or intrusion of subsurface materials, such as diapirs. The tectonic processes might be related to tidal flexing of the icy lithosphere on diurnal or longer timescales. Crater materials include various interior (smooth central, rough inner, and annular massif) and exterior (continuous ejecta) subunits. Structural features and landforms are shown with conventional symbols. Type localities for the units are identified, along with suggestions for portraying the features on geological maps, including colors and letter abbreviations for material units. Implementing these suggestions by the planetary mapping community would facilitate comparisons of maps for different parts of Europa and contribute to an eventual global synthesis of its complex geology. On the basis of initial mapping results, a stratigraphic sequence is suggested in which ridged plains form the oldest unit on Europa, followed by development of band material and individual ridges. Band materials tend to be somewhat older than ridges, but in many areas the two units formed simultaneously. Similarly, the formation of most chaos follows the development of ridged plains; although chaos is among the youngest materials on Europa, some chaos units might have formed contemporaneously with ridged plains. Smooth plains generally embay all other units and are late-stage in the evolution of the surface. C1 craters are superposed on ridged plains but are crosscut by other materials, including bands and ridges. Most c2 craters postdate all other units, but a few c2 craters are cut by ridge material. C3 craters constitute the youngest recognizable material on Europa. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. Cornell Univ, Ctr Radiophys & Space Phys, Ithaca, NY 14853 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. US Geol Survey, Flagstaff, AZ 86002 USA. RP Greeley, R (reprint author), Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. NR 63 TC 65 Z9 66 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 SEP 25 PY 2000 VL 105 IS E9 BP 22559 EP 22578 DI 10.1029/1999JE001173 PG 20 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 360EC UT WOS:000089652600007 ER PT J AU Phillips, CB McEwen, AS Hoppa, GV Fagents, SA Greeley, R Klemaszewski, JE Pappalardo, RT Klaasen, KP Breneman, HH AF Phillips, CB McEwen, AS Hoppa, GV Fagents, SA Greeley, R Klemaszewski, JE Pappalardo, RT Klaasen, KP Breneman, HH TI The search for current geologic activity on Europa SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GALILEAN SATELLITES; SUBSURFACE OCEAN; ICE SHELL; STATE; PERFORMANCE; FEATURES; TEMPERATURES; CALIBRATION; VOLCANISM; MIXTURES AB Observational evidence and theoretical arguments suggest that Jupiter's satellite Europa could be geologically active and possess an "ocean" of liquid water beneath its surface at the present time. We have searched for evidence of current geologic activity on Europa in the form of active plumes venting material above the surface and by comparison of Voyager and Galileo images to look for any changes on the surface. So far, we have observed no plumes and have detected no definitive changes. The lack of observed activity allows us to estimate a maximum steady state surface alteration rate of 1 km(2) y(-1) in the regions analyzed, assuming alterations will cover contiguous areas of at least 4 km(2) over a period of 20 years. Assuming this as a constant, globally uniform resurfacing rate leads to a minimum average surface age of 30 million years. We also suggest that the lack of obvious circular albedo patterns on the surface due to plumes, coupled with the presence of bright-rayed craters such as Pwyll and the predicted sputtering erosion rate, implies that no large-scale plume activity has taken place over at least the last few thousand years. We thus conclude that if Europa's surface is currently active, any changes must be relatively small in spatial scale or episodic in nature rather than continuous. To detect potential small-scale surface changes, we need high-resolution comparisons between the Galileo data and future Europa Orbiter images. C1 Univ Arizona, Lunar & Planetary Lab, Dept Planetary Sci, Tucson, AZ 85721 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. RP Phillips, CB (reprint author), Univ Arizona, Lunar & Planetary Lab, Dept Planetary Sci, Tucson, AZ 85721 USA. RI Fagents, Sarah/B-3983-2014 NR 63 TC 37 Z9 38 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-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 2000 VL 105 IS E9 BP 22579 EP 22597 DI 10.1029/1999JE001139 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 360EC UT WOS:000089652600008 ER PT J AU Fanale, FP Granahan, JC Greeley, R Pappalardo, R Head, J Shirley, J Carlson, R Hendrix, A Moore, J McCord, TB Belton, M AF Fanale, FP Granahan, JC Greeley, R Pappalardo, R Head, J Shirley, J Carlson, R Hendrix, A Moore, J McCord, TB Belton, M CA Galileo NIMS SSI Instrument Teams TI Tyre and Pwyll: Galileo orbital remote sensing of mineralogy versus morphology at two selected sites on Europa SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INFRARED MAPPING SPECTROMETER; SPECTRAL REFLECTANCE; SURFACE; SATELLITES; FEATURES AB Observational data from the Galileo Orbiter's remote-sensing instruments, including solid-state imaging (SSI), the Near-Infrared Mapping Spectrometer (NIMS), and the ultraviolet spectrometer (UVS), are analyzed and interpreted in terms of the history of the Tyre and Pwyll impact sites and the nature of Europa's crustal zonal structure. Material characterized by asymmetric 1.4 and 2.0 mu m bands and visible coloration characterizes each site where morphologic evidence suggests disruption of the topmost crust, The material is not H2O ice, is endogenic, and is common to the linea, impact basins, and dark trailing side terrain. Differences between Tyre and Pwyll are interpreted in terms of Europa's peculiar energy history, while other evidence may suggest flooding of the endogenic material as a liquid. The pure ice appearance of most of Europa's crust is probably superficial, while beneath a thin patina of sputtered H2O molecules the crust is everywhere laced with numerous generations of intrusions and extrusions of an aqueous phase. Our results, together with numerous laboratory experiments and theoretical analysis, suggest that the aqueous phase is dominated by the SO4= anion. C1 Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Sci & Technol Int, Honolulu, HI USA. Marconi Integrated Syst, San Diego, CA USA. Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Natl Org Astron Observ, Tucson, AZ 85726 USA. RP Fanale, FP (reprint author), Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, 2525 Correa Rd, Honolulu, HI 96822 USA. NR 30 TC 16 Z9 16 U1 1 U2 2 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 SEP 25 PY 2000 VL 105 IS E9 BP 22647 EP 22655 DI 10.1029/1999JE001102 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 360EC UT WOS:000089652600012 ER PT J AU Kadel, SD Chuang, FC Greeley, R Moore, JM AF Kadel, SD Chuang, FC Greeley, R Moore, JM CA Galileo SSI Team TI Geological history of the Tyre region of Europa: A regional perspective on Europan surface features and ice thickness SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CONAMARA CHAOS REGION; SUBSURFACE OCEAN; GALILEO; GANYMEDE; CALLISTO; MODEL; SHELL AB Galileo images of the Tyre Macula region of Europa at regional (170 m/pixel) and local (similar to 40 m/pixel) scales allow mapping and understanding of surface processes and landforms. Ridged plains, doublet and complex ridges, shallow pits, domes, "chaos" areas, impact structures, tilted blocks and massifs, and young fracture systems indicate a complex history of surface deformation on Europa. Regional and local morphologies of the Tyre region of Europa suggest that an impactor penetrated through several kilometers of water ice to a mobile layer below. The surface morphology was initially dominated by formation of ridged plains, followed by development of ridge bands and doublet ridges, with chaos and fracture formation dominating the latter part of the geologic history of the Tyre region. Two distinct types of chaos have been identified which, along with upwarped dome materials, appear to represent a continuum of features (domes-platy chaos-knobby chaos) resulting from increasing degrees of surface disruption associated with local lithospheric heating and thinning. Local and regional stratigraphic relationships, block heights, and the morphology of the Tyre impact structure suggest the presence of low-viscosity ice or liquid water beneath a thin (several kilometers) surface ice shell at the time of the impact. The very low impact crater density on the surface of Europa suggests that this thin shell has either formed or been thoroughly resurfaced in the very recent past. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Kadel, SD (reprint author), Arizona State Univ, Dept Geol, Box 871404, Tempe, AZ 85287 USA. NR 52 TC 19 Z9 19 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-PLANET JI J. Geophys. Res.-Planets PD SEP 25 PY 2000 VL 105 IS E9 BP 22657 EP 22669 DI 10.1029/1999JE001203 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 360EC UT WOS:000089652600013 ER PT J AU Boto, AN Kok, P Abrams, DS Braunstein, SL Williams, CP Dowling, JP AF Boto, AN Kok, P Abrams, DS Braunstein, SL Williams, CP Dowling, JP TI Quantum interferometric optical lithography: Exploiting entanglement to beat the diffraction limit SO PHYSICAL REVIEW LETTERS LA English DT Article ID STATES; INTERFERENCE; ENHANCEMENT; FREQUENCY; PHOTONS AB Classical optical lithography is diffraction limited to writing features of a size lambda/2 or greater, where lambda is the optical wavelength. Using nonclassical photon-number states, entangled N at a time, we show that it is possible to write features of minimum size lambda/(2N) in an N-photon absorbing substrate. This result allows one to write a factor of N-2 more elements on a semiconductor chip. A factor of N = 2 can be achieved easily with entangled photon pairs generated from optical parametric down-conversion. It is shown how to write arbitrary 2D patterns by using this method. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Coll N Wales, Bangor LL57 1UT, Gwynedd, Wales. RP Boto, AN (reprint author), CALTECH, Jet Prop Lab, Mail Stop 126-347,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Braunstein, Samuel/A-5501-2009; Kok, Pieter/B-1658-2010; DOWLING, JONATHAN/L-2749-2013 NR 25 TC 750 Z9 761 U1 4 U2 58 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD SEP 25 PY 2000 VL 85 IS 13 BP 2733 EP 2736 DI 10.1103/PhysRevLett.85.2733 PG 4 WC Physics, Multidisciplinary SC Physics GA 356WD UT WOS:000089465100020 ER PT J AU Taylor, ME Blaney, DL Cardell, G AF Taylor, ME Blaney, DL Cardell, G TI Elemental fractionation in ultraviolet laser ablation sampling of igneous silicate minerals relevant to Mars SO APPLIED SURFACE SCIENCE LA English DT Article DE ablation; fractionation; stoichiometry; silicate minerals; ICP-AES; ICP-MS ID ATOMIC EMISSION-SPECTROMETRY; PLASMA-MASS SPECTROMETRY; GEOLOGICAL SAMPLES; MICROANALYSIS AB Laser ablation sampling (LAS) has significant potential for remote terrestrial and extraterrestrial applications if fractionation can be understood and controlled. This study focuses on acmite, albite, augite, diopside, forsterite, and labradorite, silicate minerals that are relevant to Mars, Earth, the moon, and asteroids. The minerals were sampled using a frequency-quadrupled Nd:YAG laser and the samples were deposited as films on graphite substrates. Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy measurements of the minerals and their films indicate sodium, magnesium, silicon, calcium, and iron fractionation. Oxygen fractionation was not indicated. A cation replacement mechanism is a potential source of fractionation. These minerals can be easily distinguished by their film compositions despite fractionation, indicating that ultraviolet laser ablation sampling is feasible for silicate minerals. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Taylor, ME (reprint author), Jet Prop Lab, MS 302-231,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 22 TC 10 Z9 10 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-4332 J9 APPL SURF SCI JI Appl. Surf. Sci. PD SEP 22 PY 2000 VL 165 IS 2-3 BP 166 EP 177 DI 10.1016/S0169-4332(00)00442-6 PG 12 WC Chemistry, Physical; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Chemistry; Materials Science; Physics GA 344KL UT WOS:000088757700012 ER PT J AU Yeomans, DK Antreasian, PG Barriot, JP Chesley, SR Dunham, DW Farquhar, RW Giorgini, JD Helfrich, CE Konopliv, AS McAdams, JV Miller, JK Owen, WM Scheeres, DJ Thomas, PC Veverka, J Williams, BG AF Yeomans, DK Antreasian, PG Barriot, JP Chesley, SR Dunham, DW Farquhar, RW Giorgini, JD Helfrich, CE Konopliv, AS McAdams, JV Miller, JK Owen, WM Scheeres, DJ Thomas, PC Veverka, J Williams, BG TI Radio science results during the NEAR-Shoemaker spacecraft rendezvous with Eros SO SCIENCE LA English DT Article ID ASTEROID-433 EROS; ORBIT; FLYBY AB We determined the mass of asteroid 433 Eros, its lower order gravitational harmonics, and rotation state, using ground-based Doppler and range tracking of the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker spacecraft and images of the asteroid's surface Landmarks. The mass of Eros is (6.687 +/- 0.003) x 10(18) grams, which, coupled with our volume estimate, implies a bulk density of 2.67 +/- 0.03 grams per cubic centimeter. The asteroid appears to have a uniform density distribution. The right ascension and declination of the rotation pole are 11.37 +/- 0.05 and 17.22 +/- 0.05 degrees, respectively, and at Least over the short term, the rotation state of Eros is stable with no measurable free precession of the spin pole. Escape velocities on the surface vary from 3.1 to 17.2 meters per second. The dynamical environment of Eros suggests that it is covered with regolith and that one might expect material transport. toward the deepest potential wells in the saddle and 5.5-kilometer crater regions. C1 CALTECH, Jet Prop Lab, Navigat & Mission Design Sect, Pasadena, CA 91109 USA. Ctr Natl Etud Spatiales, Dept Terr & Planetary Geodesy, F-31055 Toulouse, France. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Cornell Univ, Ithaca, NY 14853 USA. Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. RP Yeomans, DK (reprint author), CALTECH, Jet Prop Lab, Navigat & Mission Design Sect, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 97 Z9 98 U1 0 U2 4 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 SEP 22 PY 2000 VL 289 IS 5487 BP 2085 EP 2088 DI 10.1126/science.289.5487.2085 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 356EG UT WOS:000089430900034 ER PT J AU Veverka, J Robinson, M Thomas, P Murchie, S Bell, JF Izenberg, N Chapman, C Harch, A Bell, M Carcich, B Cheng, A Clark, B Domingue, D Dunham, D Farquhar, R Gaffey, MJ Hawkins, E Joseph, J Kirk, R Li, H Lucey, P Malin, M Martin, P McFadden, L Merline, WJ Miller, JK Owen, WM Peterson, C Prockter, L Warren, J Wellnitz, D Williams, BG Yeomans, DK AF Veverka, J Robinson, M Thomas, P Murchie, S Bell, JF Izenberg, N Chapman, C Harch, A Bell, M Carcich, B Cheng, A Clark, B Domingue, D Dunham, D Farquhar, R Gaffey, MJ Hawkins, E Joseph, J Kirk, R Li, H Lucey, P Malin, M Martin, P McFadden, L Merline, WJ Miller, JK Owen, WM Peterson, C Prockter, L Warren, J Wellnitz, D Williams, BG Yeomans, DK TI NEAR at Eros: Imaging and spectral results SO SCIENCE LA English DT Article ID ASTEROID RENDEZVOUS MISSION; NEAR-INFRARED SPECTROMETER; MULTISPECTRAL IMAGER; EJECTA BLOCKS; 433-EROS; IDA; DISCOVERY; 243-IDA; GASPRA; FLYBY AB Eros is a very elongated (34 kilometers by 11 kilometers by 11 kilometers) asteroid, most of the surface of which is saturated with craters smaller than 1 kilometer in diameter. The Largest crater is 5.5 kilometers across, but there is a 10-kilometer saddle-like depression with attributes of a large degraded crater. Surface Lineations, both grooves and ridges, are prominent on Eros; some probably exploit planes of weakness produced by collisions on Ems and/or its parent body. Ejecta blocks (30 to 100 meters across) are abundant but not uniformly distributed over the surface. Albedo variations are restricted to the inner walls of certain craters and may be related to downslope movement of regolith. On scales of 200 meters to 1 kilometer, Eros is more bland in terms of color variations than Gaspra or Ida. Spectra (800 to 2500 nanometers) are consistent with an ordinary chondrite composition for which the measured mean density of 2.67 +/- 0.1 grams per cubic centimeter implies internal porosities ranging from about 10 to 30 percent. C1 Cornell Univ, Ithaca, NY 14853 USA. Northwestern Univ, Dept Geol Sci, Evanston, IL 60208 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. SW Res Inst, Boulder, CO 80302 USA. Rensselaer Polytech Inst, Ctr Sci, Dept Earth & Environm Sci, Troy, NY 12180 USA. US Geol Survey, Flagstaff, AZ 86001 USA. Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Malin Space Sci Syst, San Diego, CA 92191 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Veverka, J (reprint author), Cornell Univ, Space Sci Bldg, Ithaca, NY 14853 USA. RI Wellnitz, Dennis/B-4080-2012; McFadden, Lucy-Ann/I-4902-2013; Murchie, Scott/E-8030-2015; Izenberg, Noam/F-3952-2015 OI McFadden, Lucy-Ann/0000-0002-0537-9975; Murchie, Scott/0000-0002-1616-8751; Izenberg, Noam/0000-0003-1629-6478 NR 61 TC 141 Z9 146 U1 0 U2 5 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 SEP 22 PY 2000 VL 289 IS 5487 BP 2088 EP 2097 DI 10.1126/science.289.5487.2088 PG 10 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 356EG UT WOS:000089430900035 ER PT J AU Zuber, MT Smith, DE Cheng, AF Garvin, JB Aharonson, O Cole, TD Dunn, PJ Guo, YP Lemoine, FG Neumann, GA Rowlands, DD Torrence, MH AF Zuber, MT Smith, DE Cheng, AF Garvin, JB Aharonson, O Cole, TD Dunn, PJ Guo, YP Lemoine, FG Neumann, GA Rowlands, DD Torrence, MH TI The shape of 433 Eros from the NEAR-Shoemaker Laser Rangefinder SO SCIENCE LA English DT Article ID ASTEROIDS; IMPACT; SATELLITES; GRAVITY; PHOBOS AB Measurements from the Near Earth Asteroid Rendezvous (NEAR)-Shoemaker Laser Rangefinder (NLR) indicate that asteroid 433 Eros is a consolidated body with a complex shape dominated by collisions. The offset between the asreroid's center of mass and center of figure indicates a small deviation from a homogeneous internal structure that is most simply explained by variations in mechanical structure. Regional-scale relief and slope distributions show evidence for control of topography by a competent substrate. impact crater morphology is influenced by both gravity and structural control. Small-scale topography reveals ridges and grooves that may be generated by impact-related fracturing. C1 MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 USA. NASA, Earth Sci Directorate, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Raytheon Informat Technol & Sci Serv, Greenbelt, MD 20771 USA. RP Zuber, MT (reprint author), MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA 02139 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 29 TC 89 Z9 92 U1 0 U2 5 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 SEP 22 PY 2000 VL 289 IS 5487 BP 2097 EP 2101 DI 10.1126/science.289.5487.2097 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 356EG UT WOS:000089430900036 ER PT J AU Trombka, JI Squyres, SW Bruckner, J Boynton, WV Reedy, RC McCoy, TJ Gorenstein, P Evans, LG Arnold, JR Starr, RD Nittler, LR Murphy, ME Mikheeva, I McNutt, RL McClanahan, TP McCartney, E Goldsten, JO Gold, RE Floyd, SR Clark, PE Burbine, TH Bhangoo, JS Bailey, SH Petaev, M AF Trombka, JI Squyres, SW Bruckner, J Boynton, WV Reedy, RC McCoy, TJ Gorenstein, P Evans, LG Arnold, JR Starr, RD Nittler, LR Murphy, ME Mikheeva, I McNutt, RL McClanahan, TP McCartney, E Goldsten, JO Gold, RE Floyd, SR Clark, PE Burbine, TH Bhangoo, JS Bailey, SH Petaev, M TI The elemental composition of asteroid 433 Eros: Results of the NEAR-Shoemaker x-ray spectrometer SO SCIENCE LA English DT Article ID RENDEZVOUS MISSION; INFRARED SPECTROMETER; MULTISPECTRAL IMAGER; TEMPERATURE; RADIATION; SPECTRUM; PLASMA AB We report major element composition ratios for regions of the asteroid 433 Eros imaged during two solar flares and quiet sun conditions during the period of May to July 2000, Low aluminum abundances for all regions argue against global differentiation of Eros. Magnesium/silicon, aluminum/silicon, calcium/silicon, and iron/silicon ratios are best interpreted as a relatively primitive, chondritic composition. Marked depletions in sulfur and possible aluminum and calcium depletions, relative to ordinary chondrites, may represent signatures of Limited partial melting or impact volatilization. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Cornell Univ, Ithaca, NY 14853 USA. Max Planck Inst Chem, D-55020 Mainz, Germany. Univ Arizona, Dept Planetary Sci, Tucson, AZ 85721 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. Comp Sci Corp, Syst Sci Div, Laurel, MD 20707 USA. Univ Calif San Diego, La Jolla, CA 92093 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. RP Trombka, JI (reprint author), NASA, Goddard Space Flight Ctr, Code 691, Greenbelt, MD 20771 USA. RI McNutt, Ralph/E-8006-2010; OI McNutt, Ralph/0000-0002-4722-9166; Reedy, Robert/0000-0002-2189-1303 NR 30 TC 89 Z9 91 U1 0 U2 3 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 SEP 22 PY 2000 VL 289 IS 5487 BP 2101 EP 2105 DI 10.1126/science.289.5487.2101 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 356EG UT WOS:000089430900037 ER PT J AU Zakharova, NT Mishchenko, MI AF Zakharova, NT Mishchenko, MI TI Scattering properties of needlelike and platelike ice spheroids with moderate size parameters SO APPLIED OPTICS LA English DT Article ID LIGHT-SCATTERING; NONSPHERICAL PARTICLES; AGGREGATE PARTICLES; OPTICAL-PROPERTIES; DEPOLARIZATION; ATMOSPHERES; JUPITER AB We use the current advanced version of the T-matrix method to compute the optical cross sections, the asymmetry parameter of the phase function, and the scattering matrix elements of ice spheroids with aspect ratios up to 20 and surface-equivalent-sphere size parameters up to 12. We demonstrate that platelike and needlelike particles with moderate size parameters possess unique scattering properties: their asymmetry parameters and phase functions are similar to those of surface-equivalent spheres, whereas all other elements of the scattering matrix are typical of particles much smaller than the wavelength (Rayleigh scatterers). This result may have important implications for optical particle sizing and remote sensing of the terrestrial and planetary atmospheres. (C) 2000 Optical Society of America OCIS codes: 010.1110, 010.1290, 010.1310, 010.2940, 290.1090, 290.1310. C1 Sci Syst & Applicat Inc, New York, NY 10025 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Zakharova, NT (reprint author), Sci Syst & Applicat Inc, 2880 Broadway, New York, NY 10025 USA. EM crntz@giss.nasa.gov RI Mishchenko, Michael/D-4426-2012 NR 19 TC 45 Z9 44 U1 0 U2 6 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 SEP 20 PY 2000 VL 39 IS 27 BP 5052 EP 5057 DI 10.1364/AO.39.005052 PG 6 WC Optics SC Optics GA 353AW UT WOS:000089252400026 PM 18350104 ER PT J AU Patel, SK Joy, M Carlstrom, JE Holder, GP Reese, ED Gomez, PL Hughes, JP Grego, L Holzapfel, WL AF Patel, SK Joy, M Carlstrom, JE Holder, GP Reese, ED Gomez, PL Hughes, JP Grego, L Holzapfel, WL TI The distance and mass of the galaxy cluster Abell 1995 derived from Sunyaev-Zeldovich effect and X-ray measurements SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; dark matter; distance scale; galaxies : clusters : individual (Abell 1995); X-rays : general ID RELATIVISTIC CORRECTIONS; VELOCITY DISPERSIONS; TEMPERATURE PROFILES; INTRACLUSTER MEDIUM; HUBBLE CONSTANT; SKY SURVEY; ABUNDANCES; H-0 AB We present multiwavelength observations of the Abell 1995 galaxy cluster. From an analysis of X-ray spectroscopy and imaging data, we derive the electron temperature, cluster core radius, and central electron number density. Using optical spectroscopy of 15 cluster members, we derive an accurate cluster redshift and velocity dispersion. Finally, the interferometric imaging of the Sunyaev-Zeldovich effect toward Abell 1995 at 28.5 GHz provides a measure of the integrated pressure through the cluster. The X-ray and Sunyaev-Zeldovich effect observations are combined to determine the angular diameter distance to the cluster of D-A = 1294(-283)(-458)(+294)(+438) Mpc (statistical followed by systematic uncertainty), implying a Hubble constant of H-0 = 52.2 (+11.4)(+18.5)(-11.9)(-17.7) km s(-1) Mpc(-1) for Ohm(M) = 0.3 and Ohm(Lambda) = 0.7. We find a best-fit H-0 of 46 km s(-1) Mpc(-1) for the Ohm(M) - 1 and Ohm(Lambda) = 0 cosmology, and 48 km s(-1) Mpc(-1) for = 0.3 and Ohm(Lambda) = 0.0. The X-ray data are also used to derive a total cluster mass of M-tot(HSE)(r(500)) = 5.18(-0.48)(+0.62) x 10(14) h(-1) M.; the optical velocity dispersion yields an independent and consistent estimate of M-tot(virial)(r(500)) = 6.35(-1.19)(+1.51) X 10(14) h(-1) M.. Both of the total mass estimates are evaluated at a fiducial radius, r(500) = 830 h(-1) kpc, where the overdensity is 500 times the critical density. The total cluster mass is then combined with gas mass measurements to determine a cluster gas mass fraction of f(g) = 0.056(-0.013)(+0.010)h(-3/2). In combination with recent baryon density constraints, the measured gas mass fraction yields an upper limit on the mass density parameter of Ohm(M) h(1/2) less than or equal to 0.34(-0.05)(+0.06). C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Rutgers State Univ, Dept Phys & Astron, Piscataway, NJ 08854 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. RP Patel, SK (reprint author), Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. RI Holzapfel, William/I-4836-2015 NR 60 TC 30 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2000 VL 541 IS 1 BP 37 EP 48 DI 10.1086/309411 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300004 ER PT J AU Palunas, P Collins, NR Gardner, JP Hill, RS Malumuth, EM Smette, A Teplitz, HI Williger, GM Woodgate, BE AF Palunas, P Collins, NR Gardner, JP Hill, RS Malumuth, EM Smette, A Teplitz, HI Williger, GM Woodgate, BE TI Wide-field imaging of Hubble Deep Field-South region. I. Quasar candidates SO ASTROPHYSICAL JOURNAL LA English DT Article DE large-scale structure of universe; quasars : emission lines; quasars : general; quasars : individual (J2233-6033); surveys ID QSO J2233-606; ALPHA EMISSION; EVOLUTION AB We present candidate quasars from a multicolor (uBVRI + narrowband) imaging survey of 1/2 square degree around the Hubble Deep Field-South (HDF-S). We identify 154 candidate quasars with B < 23 using color selection, consistent with previously measured QSO number counts if we assume a 60% selection efficiency. The narrowband filter (NB) was centered at 3958 Angstrom to detect Ly alpha at the redshift of J2233-6033, the HDF-S QSO. We confirm the presence of Ly alpha nebulosity extending similar to 12" around the HDF-S QSO, reported by Bergeron and coworkers. We detect 10 pointlike objects in emission through the NE filter. Of these, seven satisfy our QSO color selection criteria. One of the emission-line objects is a B similar to 20 radio-quiet quasar at z = 1.56, 6.'7 from the line of sight to the HDF-S QSO and similar to 12" from the western edge of the WFPC2 deep field. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Palunas, P (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. RI Woodgate, Bruce/D-2970-2012 NR 24 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2000 VL 541 IS 1 BP 61 EP 65 DI 10.1086/309434 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300007 ER PT J AU Lister, ML Smith, PS AF Lister, ML Smith, PS TI Intrinsic differences in the inner jets of high and low optically polarized radio quasars SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : jets; galaxies : magnetic fields; quasars : general; polarization; shock waves ID BL LACERTAE OBJECTS; BASE-LINE INTERFEROMETRY; RANGE VLA OBSERVATIONS; VLBI OBSERVATIONS; COMPLETE SAMPLE; MAGNETIC-FIELDS; 22 GHZ; 43 GHZ; POLARIMETRY; BLAZARS AB A significant fraction of flat-spectrum, radio-loud quasars display most of the characteristics of relativistically beamed, high-optical polarization blazars yet are weakly polarized in the optical regime (m(opt) less than or similar to 3%). We have conducted a high-resolution polarization study with the VLBA at 22 and 43 GHz to look for differences in the parsec-scale magnetic field structures of 18 high and low optically polarized, compact radio-loud quasars (HPQs and LPRQs, respectively). We find a strong correlation between the polarization level of the unresolved parsec-scale radio core at 43 GHz and overall optical polarization of the source, which suggests a common (possibly cospatial) origin for the emission at these two wavelengths. The electric vectors of the polarized 43 GHz radio cores are roughly aligned with the inner jet direction, indicating magnetic fields perpendicular to the flow. Similar orientations are seen in the optical, which suggests that the polarized flux at both wavelengths is caused by one or more strong transverse shocks located very close to the base of the jet. In LPRQs, these shocks appear to be weak near the core and gradually increase in strength down the jet. The LPRQs in our sample tend to have less luminous radio cores than the HPQs and jet components with magnetic fields predominantly parallel to the jet. The components in HPQ jets, on the other hand, tend to have perpendicular magnetic field orientations. These differences cannot be accounted for by a simple model in which HPQs and LPRQs are the same type of object seen at different angles to the line of sight. A more likely scenario is that LPRQs represent a quiescent phase of blazar activity in which the inner jet flow does not contain strong shocks. Our high-resolution observations have shown that high rotation measures (up to 3000 rad m(-2)) previously seen in the nuclear regions of HPQs are present in LPRQs as well. The low-redshift quasars in our sample tend to have jet components with larger 43/22 GHz depolarization ratios than those found in the high-redshift sources. This may be caused by small-scale magnetic field fluctuations in the Faraday screens that are being smeared out in the high-redshift sources by the poorer spatial resolution of the restoring beam. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. RP Lister, ML (reprint author), CALTECH, Jet Prop Lab, MS 238-332,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 57 TC 58 Z9 58 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2000 VL 541 IS 1 BP 66 EP 87 DI 10.1086/309413 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300008 ER PT J AU Xu, C AF Xu, C TI Local luminosity function at 15 microns and galaxy evolution seen by ISOCAM 15 micron surveys SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : luminosity function, mass function; galaxies : photometry; galaxies : starburst; galaxies : statistics; infrared : galaxies ID HUBBLE-DEEP-FIELD; BACKGROUND EXPERIMENT SEARCH; STAR-FORMATION HISTORY; SOURCE COUNTS; NUMBER COUNTS; IRAS GALAXIES; COBE; REDSHIFT; SUBMILLIMETER; EMISSION AB A local luminosity function at 15 mu m is derived using the bivariate (15 pm vs. 60 mu m luminosity) method, based on the newly published ISOCAM LW3 band (15 mu m) survey of the very deep IRAS 60 mu m sample in the north ecliptic pole region (NEPR). New IRAS 60 pm fluxes are obtained using the SCANPI/SUPERSCANPI software at the new ISOCAM positions of the sources in the sample. It is found to be in excellent agreement with the 15 mu m local luminosity function published by Xu et al., which is derived from the predicted 15 mu m luminosities of a sample of IRAS 25 mu m-selected galaxies. Model predictions of number counts and redshift distributions based on the local luminosity function and assumptions of its evolution with redshift are calculated and compared with the data of ISOCAM 15 mu m surveys. Strong luminosity evolution on the order of L proportional to(1 + z)(4.5) is suggested in these comparisons, while pure density evolution can be ruled out with high confidence. The sharp peak at about 0.4 mJy in the Euclidean normalized differential counts at 15 mu m can be explained by the effects of midinfrared broadband emission features, eliminating the need for any hypothesis for a "new population." It is found that the contribution from the population represented by ISOCAM 15 mu m sources can account for the entire IR/submillimeter background, leaving little room for any missing "new population" which can be significant energy sources of the IR/submillimeter sky. C1 CALTECH 100 22, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. RP Xu, C (reprint author), CALTECH 100 22, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. NR 42 TC 50 Z9 50 U1 0 U2 0 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 SEP 20 PY 2000 VL 541 IS 1 BP 134 EP 141 DI 10.1086/309401 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300014 ER PT J AU Slavin, JD McKee, CF Hollenbach, DJ AF Slavin, JD McKee, CF Hollenbach, DJ TI Photoionization of galactic halo gas by old supernova remnants SO ASTROPHYSICAL JOURNAL LA English DT Article DE Galaxy : halo; ISM : clouds; ISM : general; supernova remnants; X-rays : ISM ID DIFFUSE INTERSTELLAR-MEDIUM; WARM IONIZED MEDIUM; EMISSION-LINE; H-I; PHYSICAL CONDITIONS; SPHERICAL CLOUDS; HOT GAS; S-II; IONIZATION; GALAXY AB We present new calculations on the contribution from cooling hot gas to the photoionization of warm ionized gas in the Galaxy. We show that hot gas in cooling supernova remnants (SNRs) is an important source of photoionization, particularly for gas in the halo. We find that in many regions at high latitude this source is adequate to account for the observed ionization, so there is no need to find ways to transport stellar photons from the disk. The flux from cooling SNRs sets a floor on the ionization along any line of sight. Our model flux is also shown to be consistent with the diffuse soft X-ray background and with soft X-ray observations of external galaxies. We consider the ionization of the clouds observed toward the halo star HD 93521, for which there are no O stars close to the line of sight. Along this line of sight, two groups of clouds (densities similar to 0.3-1 cm(-3) and temperatures similar to 7000 K) are observed at similar to 0 km s(-1) ("slow") and similar to-50 km s(-1) ("fast"). We show that the observed ionization can be explained successfully by our model EUV/soft X-ray Bur from cooling hot gas. In particular, we can match the H alpha intensity, the S++/S+ ratio, and the C+* column. Our models show that it is possible to account for the observed ionization without invoking exotic ionization mechanisms such as decaying neutrinos (Sciama). Our value for X-ray opacity along this line of sight is somewhat larger than the average for the halo found by Arabadjis & Bregman, but we do not regard the difference as significant. From observations of the ratios of columns of C+* and either S+ or H-0, we are able to estimate the thermal pressure in the clouds. The slow clouds require high (similar to 10(4) cm(-3) K) thermal pressures to match the NC+*/NS+ ratio. Additional heating sources are required for the slow clouds to maintain their similar to 7000 K temperatures at these pressures, as found by Reynolds, Haffner, & Tufte. We also estimate the fraction of the line of sight that is occupied by warm ionized and neutral gas and find it to be small, only 6%-9%. C1 Univ Calif Berkeley, Dept Phys & Astron, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Slavin, JD (reprint author), NASA, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. NR 72 TC 36 Z9 36 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2000 VL 541 IS 1 BP 218 EP 233 DI 10.1086/309409 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300022 ER PT J AU Jura, M Chen, C Werner, MW AF Jura, M Chen, C Werner, MW TI The dust ring around AC Herculis SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; stars : AGB and post-AGB; stars : winds, outflows ID RV-TAURI STARS; BIPOLAR PREPLANETARY NEBULAE; CARBON-RICH STARS; CIRCUMSTELLAR ENVELOPES; ACCRETION DISKS; BINARY-SYSTEMS; WIND; HYDRODYNAMICS; PHOTOMETRY; OBJECTS AB We have used the Reck I telescope to obtain images at 11.7 and 18.7 mu m of AC Her, a postasymptotic giant branch spectroscopic binary. The source is resolved into two spots separated by about 0." 6, which can be explained as emission from particles associated with an edge-on dust ring with a radius of approximately 300 AU that is oriented approximately north-south. We propose that the ring is mainly composed of particles that are larger than 200 mu m in radius that are orbiting the binary, while the infrared emission that we observe is emitted by small grains with sizes less than 1 mu m that are not gravitationally bound and, instead, are flowing out in a wind from the ring. We propose that collisions among the larger ring particles produce the smaller wind particles. Whether most of the 10(30) g of dust orbiting AC Her ultimately is expelled in a wind or coalesces into macroscopic objects is unknown. C1 Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jura, M (reprint author), Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. NR 32 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2000 VL 541 IS 1 BP 264 EP 269 DI 10.1086/309417 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300027 ER PT J AU Hanson, MM Still, MD Fender, RP AF Hanson, MM Still, MD Fender, RP TI Orbital dynamics of Cygnus X-3 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : close; circumstellar matter; infrared : stars; stars : individual (Cygnus X-3) ID WOLF-RAYET STARS; BLACK-HOLE; X-RAY; PULSAR; VARIABILITY; COMPANION; DISTANCE; OUTBURST; MODELS; LINES AB Orbital-phase-resolved infrared spectra of Cygnus X-3 in outburst and quiescence, including tomographic analysis, are presented, We confirm the phasing of broad He II and N V lines in quiescence, such that maximum blueshift corresponds to the X-ray minimum at Phi = 0.00 +/- 0.04. In outburst, double-peaked He I structures show a similar phasing with two significant differences: (1) although varying in relative strength, there is continuous line emission in blue and red peaks around the orbit; and (2) an absorption component, similar to 1/4 of an orbit out of phase with the emission features, is discerned. Doppler tomograms of the double-peaked profiles are consistent with a disk-wind geometry, rotating at velocities of 1000 km s(-1). Regrettably, the tomography algorithm will produce a similar ring structure from alternative line sources if contaminated by overlying P Cygni profiles. This is certainly the case in the strong 2.0587 mu m He I line, leading to an ambiguous solution for the nature of double-peaked emission. The absorption feature, detected 1/4 of an orbit out of phase with the emission features, is consistent with an origin in the He star wind and yields for the first time a plausible radial velocity curve for the system. We directly derive the mass function of the system, 0.027 M.. If we assume a neutron star accretor and adopt a high orbital inclination, i > 60 degrees, we obtain a mass range for the He star of 5 M. less than or similar to M-WR less than or similar to 11 M.. Alternatively, if the compact object is a black hole, we estimate M-BH less than or similar to 10 M.. We discuss the implications of these masses for the nature and size of the binary system. C1 Univ Cincinnati, Dept Phys, Cincinnati, OH 45221 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Ctr High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands. RP Hanson, MM (reprint author), Univ Cincinnati, Dept Phys, Cincinnati, OH 45221 USA. NR 35 TC 41 Z9 41 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2000 VL 541 IS 1 BP 308 EP 318 DI 10.1086/309419 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300031 ER PT J AU Saumon, D Geballe, TR Leggett, SK Marley, MS Freedman, RS Lodders, K Fegley, B Sengupta, SK AF Saumon, D Geballe, TR Leggett, SK Marley, MS Freedman, RS Lodders, K Fegley, B Sengupta, SK TI Molecular abundances in the atmosphere of the T dwarf G1 229B SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : abundances; stars : atmospheres; stars : individual (G1 229B); stars : low-mass, brown dwarfs ID COOL BROWN DWARF; GLIESE 229B; CARBON-MONOXIDE; GIANT PLANETS; CHEMISTRY; SPECTRUM; JUPITER; METHANE; DISCOVERY; MODELS AB We present new high-resolution infrared spectra of the T dwarf Gliese 229B in the J, H, and K bandpasses. We analyze each of these as well as previously published spectra to determine its metallicity and the abundances of NH, and CO in terms of the surface gravity of G1 229B, which remains poorly constrained. The metallicity increases with increasing gravity and is below the solar value unless G1 229B is a high-gravity brown dwarf with log g (cgs) approximate to 5.5. The NH3 abundance is determined from both the Hand the K-band spectra, which probe two different levels in the atmosphere. We find that the abundance from the K-band data is well below that expected from chemical equilibrium, which we interpret as strong evidence for dynamical transport of NH3 in the atmosphere. This is consistent with the previous detection of CO and provides additional constraints on the dynamics of the atmosphere of this T dwarf. C1 Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37235 USA. Gemini N Observ, Hilo, HI 96720 USA. Joint Astron Ctr, Hilo, HI 96720 USA. New Mexico State Univ, Dept Astron, Las Cruces, NM 88003 USA. NASA, Ames Res Ctr, Space Phys Res Inst, Moffett Field, CA 94035 USA. Washington Univ, Dept Earth & Planetary Sci, Planetary Chem Lab, St Louis, MO 63130 USA. Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37235 USA. RP Saumon, D (reprint author), Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37235 USA. RI Marley, Mark/I-4704-2013; OI Leggett, Sandy/0000-0002-3681-2989 NR 39 TC 93 Z9 93 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2000 VL 541 IS 1 BP 374 EP 389 DI 10.1086/309410 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300038 ER PT J AU Lowrance, PJ Schneider, G Kirkpatrick, JD Becklin, EE Weinberger, AJ Zuckerman, B Plait, P Malmuth, EM Heap, SR Schultz, A Smith, BA Terrile, J Hines, DC AF Lowrance, PJ Schneider, G Kirkpatrick, JD Becklin, EE Weinberger, AJ Zuckerman, B Plait, P Malmuth, EM Heap, SR Schultz, A Smith, BA Terrile, J Hines, DC TI A candidate substellar companion to HR 7329 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : low-mass, brown dwarfs ID LOW-MASS STARS; MODEL ATMOSPHERES; SPECTRAL SEQUENCE; BETA-PICTORIS; BROWN DWARFS; NEARBY STARS; AGE AB We present the discovery of a candidate substellar companion from a survey of nearby young stars made with the Near-Infrared Camera and Multiobject Spectrometer coronagraph on the Hubble Space Telescope. The H approximate to 12 mag object was discovered approximately 4 " from the young A0 V star HR 7329. Using follow-up spectroscopy from the Space Telescope Imaging Spectrograph, we derive a spectral type between M7 V and M8 V with an effective temperature of similar to 2600 K. We estimate that the probability of a chance alignment with a foreground dwarf star of this nature is similar to 10(-8), and therefore we suggest that the object (HR 7329B) is physically associated with HR 7329, with a projected separation of 200 AU. Current brown dwarf cooling models indicate a mass of less than 50 M-Jup for HR 7329B based on age estimates of less than or equal to 30 Myr for HR 7329A. C1 Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. Univ Arizona, Dept Astron, Tucson, AZ 85721 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. CALTECH, Infrared Proc & Anal Ctr, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Adv Comp Concepts Inc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. Comp Sci Corp, Lanham, MD 20706 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lowrance, PJ (reprint author), Univ Calif Los Angeles, Dept Phys & Astron, 405 Hilgard Ave, Los Angeles, CA 90095 USA. OI Weinberger, Alycia/0000-0001-6654-7859 NR 30 TC 104 Z9 104 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2000 VL 541 IS 1 BP 390 EP 395 DI 10.1086/309437 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300039 ER PT J AU Smith, SJ Greenwood, JB Chutjian, A Tayal, SS AF Smith, SJ Greenwood, JB Chutjian, A Tayal, SS TI Electron excitation cross sections for the 3s(2)3p(2) P-3 -> 3s3p(3) S-5(o) transition in S2+ SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; atomic processes ID IO-PLASMA TORUS; S-III; OSCILLATOR-STRENGTHS; TEMPERATURE; JUPITER AB Experimental and theoretical collisional excitation cross sections are reported for the 3s(2)3p(2) P-3-->3s3p(3) S-5(o) spin-forbidden transition in S2+. Th, transition energies (wavelengths) are 7.171 eV (1728.9 Angstrom, J = 2 --> 2) and 7.237 eV (1713.1 Angstrom J = 2 --> 1). In the experimental approach, use is made of the electron energy-loss method with merged electron and ion beams. The metastable fraction in the S2+ beam is assessed and minimized. A novel "electronic aperture" is used to limit the trajectories of elastically scattered electrons into the trochoidal electrostatic analyzer. Theoretically, the R-matrix method in a 17 state and a 27 state calculation is used to obtain cross sections from threshold to. 15.0 eV. Good agreement is found between experiment and the results of the 27 state theory. The presence of two strong resonances near threshold (7.5-9.0 eV) and a third resonance above threshold (11.5 eV) is verified by experiment. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Clark Atlanta Univ, Dept Phys, Atlanta, GA 30314 USA. RP Smith, SJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Greenwood, Jason/L-4799-2014 NR 18 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 20 PY 2000 VL 541 IS 1 BP 501 EP 505 DI 10.1086/309405 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360YE UT WOS:000089694300050 ER PT J AU Weatherhead, EC Reinsel, GC Tiao, GC Jackman, CH Bishop, L Frith, SMH DeLuisi, J Keller, T Oltmans, SJ Fleming, EL Wuebbles, DJ Kerr, JB Miller, AJ Herman, J McPeters, R Nagatani, RM Frederick, JE AF Weatherhead, EC Reinsel, GC Tiao, GC Jackman, CH Bishop, L Frith, SMH DeLuisi, J Keller, T Oltmans, SJ Fleming, EL Wuebbles, DJ Kerr, JB Miller, AJ Herman, J McPeters, R Nagatani, RM Frederick, JE TI Detecting the recovery of total column ozone SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC OZONE; ANTARCTIC OZONE; TRENDS; TEMPERATURE; NIMBUS-7; LATITUDE; UMKEHR; HOLE AB International agreements for the limitation of ozone-depleting substances have already resulted in decreases in concentrations of some of these chemicals in the troposphere. Full compliance and understanding of all factors contributing to ozone depletion are still uncertain; however, reasonable expectations are for a gradual recovery of the ozone layer over the next 50 years. Because of the complexity of the processes involved in ozone depletion, it is crucial to detect not just a decrease in ozone-depleting substances but also a recovery in the ozone layer. The recovery is likely to be detected in some areas sooner than others because of natural variability in ozone concentrations. On the basis of both the magnitude and autocorrelation of the noise from Nimbus 7 Total Ozone Mapping Spectrometer ozone measurements, estimates of the time required to detect a fixed trend in ozone at various locations around the world are presented. Predictions from the Goddard Space Flight Center (GSFC) two-dimensional chemical model are used to estimate the time required to detect predicted trends in different areas of the world. The analysis is based on our current understanding of ozone chemistry, full compliance with the Montreal Protocol and its amendments, and no intervening factors, such as major volcanic eruptions or enhanced stratospheric cooling. The results indicate that recovery of total column ozone is likely to be detected earliest in the Southern Hemisphere near New Zealand, southern Africa, and southern South America and that the range of time expected to detect recovery for most regions of the world is between 15 and 45 years. Should the recovery be slower than predicted by the GSFC model, owing, for instance, to the effect of greenhouse gas emissions, or should measurement sites be perturbed, even longer times would be needed for detection. C1 Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA. Univ Wisconsin, Dept Stat, Madison, WI 53706 USA. Univ Chicago, Grad Sch Business, Chicago, IL 60637 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD USA. Allied Signal Corp, Buffalo, NY 14210 USA. Steven Myers & Assoc Corp, Arlington, VA 22201 USA. NOAA, Air Resources Lab, Boulder, CO 80303 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Univ Illinois, Dept Atmospher Sci, Champaign, IL 61801 USA. Atmospher Environm Serv, Downsview, ON M3H 5T4, Canada. Natl Weather Serv, Washington, DC 20233 USA. Univ Chicago, Dept Geophys Sci, Chicago, IL 60637 USA. RP Weatherhead, EC (reprint author), Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA. RI Jackman, Charles/D-4699-2012; McPeters, Richard/G-4955-2013; Weatherhead, Elizabeth/I-7091-2015; OI McPeters, Richard/0000-0002-8926-8462; Weatherhead, Elizabeth/0000-0002-9252-4228; Herman, Jay/0000-0002-9146-1632 NR 27 TC 76 Z9 85 U1 2 U2 15 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 SEP 16 PY 2000 VL 105 IS D17 BP 22201 EP 22210 DI 10.1029/2000JD900063 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 356XH UT WOS:000089469100006 ER PT J AU Alexander, MJ Beres, JH Pfister, L AF Alexander, MJ Beres, JH Pfister, L TI Tropical stratospheric gravity wave activity and relationships to clouds SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SEMIANNUAL OSCILLATION; DEEP CONVECTION; MOMENTUM FLUX; STEP; CIRCULATION; TURBULENCE; AIRCRAFT; MODEL; CYCLE; WIND AB Wind measurements from NASA's ER-2 aircraft in the stratosphere are used to obtain information on the momentum flux carried by gravity waves with horizontal wavelengths between 5 and 150 km. Tropical data are compared with the cloud brightness temperature below the aircraft as an indicator of deep convective activity. A striking correlation between cold, high clouds and large gravity wave momentum flux is seen in data from the Stratosphere-Troposphere Exchange Project (STEP) tropical campaign during the monsoon season over northern Australia and Indonesia. There is an enhancement in the flux carried by waves propagating against the background wind in these observations. The same analysis was performed with data from more recent ER-2 flights over the tropical Pacific Ocean during the Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA), Stratospheric Tracers of Atmospheric Transport (STRAT), and Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) campaigns which took place in 1994, 1995-1996, and 1997, respectively. These data also show a correlation between gravity wave momentum flux and deep convective clouds, but the relationship is much weaker, and the magnitudes of the momentum flux over the deepest clouds are about 7 times smaller than those seen in the STEP data. The reasons for these differences remain uncertain, but possibilities include both real geophysical differences and differences associated with the flight paths during the 1987 versus later campaigns. C1 Colorado Res Assoc, Boulder, CO 80301 USA. Univ Washington, Seattle, WA 98195 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Alexander, MJ (reprint author), Colorado Res Assoc, 3380 Mitchell Lane, Boulder, CO 80301 USA. EM alexand@colorado-research.com; beres@atmos.washington.edu; pfister@telsci.arc.nasa.gov NR 36 TC 49 Z9 50 U1 0 U2 6 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 SEP 16 PY 2000 VL 105 IS D17 BP 22299 EP 22309 DI 10.1029/2000JD900326 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 356XH UT WOS:000089469100013 ER PT J AU Kletetschka, G Taylor, PT Wasilewski, PJ Hill, HGM AF Kletetschka, G Taylor, PT Wasilewski, PJ Hill, HGM TI Magnetic properties of aggregate polycrystalline diamond: implications for carbonado history SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article DE diamond; carbonade; magnetic properties; impact features; magnetic hysteresis ID CRETACEOUS-TERTIARY BOUNDARY; EARTH ELEMENT PATTERNS; CHICXULUB CRATER; CRUSTAL ORIGIN; IMPACT CRATER; MELT ROCK; INCLUSIONS; ISOTOPES; TEKTITES; PHASES AB Carbonados are aggregate polycrystalline diamonds and are found in placer deposits of the Central African Republic (CAR) and the Bahia Province of Brazil. Their origin is uncertain, but several mutually exclusive hypotheses have been proposed ranging from extraterrestrial to crustal, and mantle provenance. In an endeavor to further our understanding of these diamonds, we performed a series of magnetic characterization studies on 20 samples from the CAR. Our results reveal that the carbonados contain material with contrasting magnetic hysteresis behavior and magnetization, Acid leaching permitted us to monitor the distribution of magnetic carriers within the samples. An absence of sample size dependence on magnetization loss indicates that the magnetic carriers are distributed at the vitreous surface; including open pores and that the carbonade interior is essentially devoid of the magnetic carriers. The diamond's isolated nonmagnetic interior of carbonados suggests that the initial formation environment was deficient in magnetic particles. The formation of the magnetic carriers is thus closely linked with the origin of the smooth surface, perhaps during the hypervelocity ejection of carbonados into the Earth's atmosphere. Partial ablation in the Earth's primordial, oxygen-poor atmosphere resulted in a fusion of the originally porous material and a decrease in the original pore density at the surface. Secondary mineralization of the impact-generated melt and/or the products of later diagenetic processes, containing the majority of the magnetic carriers, filled the remainder of the open pores. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. RP Kletetschka, G (reprint author), NASA, Goddard Space Flight Ctr, Geodynam Branch, Code 921, Greenbelt, MD 20771 USA. RI Kletetschka, Gunther/C-9996-2011; Taylor, Patrick/D-4707-2012 OI Kletetschka, Gunther/0000-0002-0645-9037; Taylor, Patrick/0000-0002-1212-9384 NR 40 TC 10 Z9 11 U1 1 U2 8 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 SEP 15 PY 2000 VL 181 IS 3 BP 279 EP 290 DI 10.1016/S0012-821X(00)00213-2 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 355PN UT WOS:000089394200002 ER PT J AU Aponte, N Gonzalez, SA Kelley, MC Tepley, CA Pi, XQ Iijima, B AF Aponte, N Gonzalez, SA Kelley, MC Tepley, CA Pi, XQ Iijima, B TI Advection of the equatorial anomaly over Arecibo by small-storm related disturbance dynamo electric fields SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOSPHERIC DISTURBANCES; RADAR AB During highly disturbed geomagnetic periods, both the Arecibo radar and the Ramey ionosonde have recorded impressive nighttime ionospheric enhancements in which the peak electron density exceeded 1x10(12)m(-3) and the F-2 peak height went above 400 km. In the past it has been suggested that these events could be caused by either a downward plasmaspheric flux that increases the density in the F region or by an eastward electric field that pushes the equatorial anomaly poleward to the Caribbean sector. On February 17-18, 1999 the Arecibo radar made observations during an event in which the electron density again rose to daytime values near midnight. For this event, the peaks in density were observed predominantly southeast of Arecibo while the ions sustained a northward-eastward motion due to an eastward-southward storm dynamo electric field. TEC maps from GPS for this night confirmed that the density enhancements were due to a poleward expansion of the equatorial anomaly. C1 Natl Astron & Ionosphere Ctr, Arecibo Observ, Arecibo, PR 00612 USA. Cornell Univ, Sch Elect Engn, Ithaca, NY 14853 USA. Jet Prop Lab, Pasadena, CA USA. RP Aponte, N (reprint author), Natl Astron & Ionosphere Ctr, Arecibo Observ, HC3 Box 53995, Arecibo, PR 00612 USA. RI Gonzalez, Sixto/G-1982-2011 OI Gonzalez, Sixto/0000-0001-5544-1426 NR 13 TC 17 Z9 17 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 SEP 15 PY 2000 VL 27 IS 18 BP 2833 EP 2836 DI 10.1029/2000GL000025 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 355MX UT WOS:000089390400003 ER PT J AU Makela, JJ Gonzalez, SA MacPherson, B Pi, XQ Kelley, MC Sultan, PJ AF Makela, JJ Gonzalez, SA MacPherson, B Pi, XQ Kelley, MC Sultan, PJ TI Intercomparisons of total electron content measurements using the Arecibo incoherent scatter radar and GPS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID IONOSPHERE; NETWORK AB We compare total electron content measurements made using the Arecibo Incoherent Scatter Radar (ISR) with those made using the Global Positioning System (GPS). The ISR measurements have a limited range for these observations, up to 1500 km. We extend these profiles to GPS heights of 20,200 km with the aid of a numerical model. We use a GPS receiver on St. Croix, which has been calibrated using JPL's Global Ionospheric Mapping (GIM) technique. In addition, we also use the ISR to calibrate GPS measurements made at Isabela, PR and see how the calibration holds up on the next day. The GIM technique gives very good results on both a quiet night and a night with a severe ionospheric depletion. Normalizing the Isabela receiver to the ISR also gives good results and shows promise as a way to independently calibrate nearby GPS receivers in the future. Finally, we give evidence that the severe depletion observed by the ISR on the night of June 25/26, 1998 was associated with an elongated TEC depletion. The structure may be related to a disturbance originating in the southern hemisphere. C1 Cornell Univ, Sch Elect & Comp Engn, Ithaca, NY 14853 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Astron & Ionosphere Ctr, Arecibo Observ, Arecibo, PR 00612 USA. USAF, Res Lab, Washington, DC 20330 USA. RP Makela, JJ (reprint author), Cornell Univ, Sch Elect & Comp Engn, Ithaca, NY 14853 USA. RI Gonzalez, Sixto/G-1982-2011 OI Gonzalez, Sixto/0000-0001-5544-1426 NR 7 TC 14 Z9 14 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 SEP 15 PY 2000 VL 27 IS 18 BP 2841 EP 2844 DI 10.1029/2000GL000023 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 355MX UT WOS:000089390400005 ER PT J AU MacPherson, B Gonzalez, SA Pi, X Kelley, M Bailey, GJ Sulzer, MP Hajj, G Buonsanto, M Wang, C AF MacPherson, B Gonzalez, SA Pi, X Kelley, M Bailey, GJ Sulzer, MP Hajj, G Buonsanto, M Wang, C TI Comparison between SUPIM simulations and measured TEC for the January, 1997 storm SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ARECIBO AB A method of extrapolating electron densities (N-e) from Incoherent Scatter Radar (ISR) data to high altitudes is presented, and is used to estimate the vertical Total Electron Content (TEC) over Arecibo, Although primarily intended for use on the N-e profiles obtained using the new topside frequency hopping mode at Arecibo which provides measurements to over 2000 km altitude, we show that if the O+-H+ transition altitude is low enough to be observed, then the method may also be applied to the data taken using the standard World Day multi-radar mode, and thus to a great fraction of the World Day data from low solar flux conditions. This method is applied to Arecibo ISR data taken during the January 6-11 1997 CEDAR storm period, and compared with measured TEC from the Global Positioning System (GPS) satellite network. In addition, the TEC is compared to TEC calculated from the Sheffield University Plasmasphere Ionosphere Model (SUPIM) as part of an ongoing project of model validation. C1 Natl Astron & Ionosphere Ctr, Arecibo Observ, Arecibo, PR 00612 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Cornell Univ, Dept Elect Engn, Ithaca, NY 14853 USA. Univ So Calif, Dept Math, Los Angeles, CA 90089 USA. RP MacPherson, B (reprint author), Natl & Ionosphere Ctr, Arecibo Observ, HC3 Box 53995, Arecibo, PR 00612 USA. RI Gonzalez, Sixto/G-1982-2011 OI Gonzalez, Sixto/0000-0001-5544-1426 NR 11 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 SEP 15 PY 2000 VL 27 IS 18 BP 2845 EP 2848 DI 10.1029/2000GL000026 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 355MX UT WOS:000089390400006 ER PT J AU Ofman, L AF Ofman, L TI Source regions of the slow solar wind in coronel streamers SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ULTRAVIOLET CORONAGRAPH SPECTROMETER; IONS; ACCELERATION; MODEL AB Recent SOHO/UVCS observations of the O5+ ion line emission at 1032 Angstrom in coronal streamers indicate that the emission is stronger by an order of magnitude at the edges (legs) of streamers than in the central core of streamers. In contrast, the brightness of the Ly-alpha emission peaks in the core of streamers. I have developed the first 2.5D, three-fluid numerical MHD model of the slow solar wind dow in a coronal streamer. Using the model I find that the-enhancement of the oxygen line emission occurs due to the enhanced abundances of O5+ ions in the legs of streamer caused by the Coulomb friction with the outflowing protons. Thus, the enhanced O5+ emission trances the source regions of the slow solar wind in coronal streamers. The identification of these regions helps to understand the origins and the composition of the slow solar wind. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon Co, ITSS, Greenbelt, MD USA. RP Ofman, L (reprint author), NASA, Goddard Space Flight Ctr, Code 682, Greenbelt, MD 20771 USA. NR 20 TC 41 Z9 41 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 SEP 15 PY 2000 VL 27 IS 18 BP 2885 EP 2888 DI 10.1029/2000GL000097 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 355MX UT WOS:000089390400016 ER PT J AU Anyamba, EK Susskind, J AF Anyamba, EK Susskind, J TI Evidence of lunar phase influence on global surface air temperature SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Intraseasonal oscillations appearing in a newly available 20-year record of satellite-derived surface air temperature are composited with respect to the lunar phase. The daily surface air temperature is one of the geophysical fields derived from the TOVS data processed at the NASA Goddard Laboratory for Atmospheres. Polar regions exhibit strong lunar phase modulation with higher temperatures occurring near full moon and lower temperatures at new moon, in agreement with previous studies. The polar response to the apparent lunar forcing is most robust in winter when solar influence is at minimum. In addition, the response appears to be influenced by ENSO events. The highest mean temperature range between full moon and new moon in the region between 60 degrees and 90 degrees latitude was recorded in 1983, 1986/87, and 1990/91. Although the largest signal is in the polar regions, anomalies tend to progress equartoward in both hemispheres so that the warming in the tropics occurs at the time of the new moon. C1 NASA, Goddard Space Flight Ctr, Gen Sci Corp, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Anyamba, EK (reprint author), Assemblies God Theol Seminary, 1435 N Glenstone Ave, Springfield, MO 65802 USA. NR 22 TC 3 Z9 3 U1 2 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 SEP 15 PY 2000 VL 27 IS 18 BP 2969 EP 2972 DI 10.1029/2000GL011651 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 355MX UT WOS:000089390400037 ER PT J AU Ukita, J Kawamura, T Tanaka, N Toyota, T Wakatsuchi, M AF Ukita, J Kawamura, T Tanaka, N Toyota, T Wakatsuchi, M TI Physical and stable isotopic properties and growth processes of sea ice collected in the southern Sea of Okhotsk SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID PACIFIC INTERMEDIATE WATER; WEDDELL SEA; SNOW COVER; ANTARCTICA; AMUNDSEN; BELLINGSHAUSEN; MICROWAVE; EXTENT; ORIGIN; ROSS AB This study presents physical and stable isotopic properties of sea ice in the southernmost section of the Sea of Okhotsk on the basis of observations and measurements made in 1995 and 1996 midwinter cruises. Structural analysis revealed that ice was predominantly of the granular type. Saucer-shaped cores and wedges were seen in the cross sections of the pancakes, which indicate a rafting event in the early stage of the pancake formation. The fraction of snow with respect to the total ice mass was estimated at similar to 8% from independent delta(18)O and density measurements. From these findings we conclude that the initial growth mechanisms of the sea ice over this region are by the frazil pancake cycle with rafting and by the snow ice formation. Analysis also shows that the formation of the snow ice induces similar to 10% more salt flux through the additional freezing of the seawater. In a short (synoptic) timescale this implies that snow becomes a negative (salting) rather than a positive (freshening) source for the buoyancy flux. These results suggest critical influence of the rapid formation of the frazil pancakes and snow ice under stormy conditions on the salt and buoyancy fluxes over the region. C1 Hokkaido Univ, Grad Sch Environm Earth Sci, Sapporo, Hokkaido 060, Japan. Hokkaido Univ, Inst Low Temp Sci, Sapporo, Hokkaido 060, Japan. Univ Alaska Fairbanks, Res Syst Global Change Int Arct Res Ctr, Fairbanks, AK USA. RP Ukita, J (reprint author), NASA, Goddard Space Flight Ctr, USRA, Code 971, Greenbelt, MD 20771 USA. RI Toyota, Takenobu/D-9101-2012 NR 34 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-OCEANS JI J. Geophys. Res.-Oceans PD SEP 15 PY 2000 VL 105 IS C9 BP 22083 EP 22093 DI 10.1029/1999JC000013 PG 11 WC Oceanography SC Oceanography GA 355DD UT WOS:000089369600015 ER PT J AU Lutz, RR AF Lutz, RR TI Extending the product family approach to support safe reuse SO JOURNAL OF SYSTEMS AND SOFTWARE LA English DT Article DE product family; product line; software safety; reuse; interferometer ID REQUIREMENTS AB Upcoming spacecraft will reuse software components to the extent that some systems will form product families of similar or identical units (e.g., a fleet of spaceborne telescopes). Missions such as these must be demonstrably safe, but the consequences of broad reuse are hard to evaluate from a software safety perspective. This paper reports experience specifying an interferometer (telescope) subsystem as a product family and supplementing the specification with results from a failure analysis. Extensions to the product family approach, with lessons learned, are discussed in three areas: (I) integration of safety analysis with the product family approach; (2) modeling decisions that have safety implications (e.g., how to handle near-commonalities, establishing a hierarchy of variabilities, and specifying dependencies among options); and (3) use of the product family requirements for design evaluation of reusable components as well as a specific product. (C) 2000 Elsevier Science Inc. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Iowa State Univ, Dept Comp Sci, 226 Atanasoff Hall, Ames, IA 50011 USA. EM rlutz@cs.iastate.edu NR 26 TC 13 Z9 13 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0164-1212 EI 1873-1228 J9 J SYST SOFTWARE JI J. Syst. Softw. PD SEP 15 PY 2000 VL 53 IS 3 BP 207 EP 217 DI 10.1016/S0164-1212(00)00012-1 PG 11 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA 354PR UT WOS:000089339300002 ER PT J AU Larruquert, JI Keski-Kuha, RAM AF Larruquert, JI Keski-Kuha, RAM TI Reflectance measurements and optical constants in the extreme ultraviolet of thin films of ion-beam-deposited carbon SO OPTICS COMMUNICATIONS LA English DT Article DE thin films; optical properties; reflectivity; far UV radiation; extreme UV radiation; optical constants; carbon films ID MULTILAYER COATINGS; CARBIDE COATINGS; DIAMOND MIRRORS; ENERGY AB Reflectance measurements of ion-beam-deposited (IBD) C films were performed in the extreme ultraviolet (EUV) spectral region from 49 to 200 nm. Near normal incidence reflectance of LED C films was determined to be higher than that of evaporated C films but lower than that of diamond. Optical constants of IBD C films were obtained from reflectance measurements as a function of the angle of incidence in the spectral range 49.0-121.6 nm. The relatively high reflectance of IBD C films in the spectral region 49-92 nm and its stability when stored in a desiccator make it an interesting coating material for the EUV. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP CSIC, Inst Fis Aplicada, C Serrano 144, Madrid 28006, Spain. EM larruquert@io.csic.es OI Larruquert, Juan/0000-0001-6356-9702 NR 27 TC 15 Z9 15 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0030-4018 EI 1873-0310 J9 OPT COMMUN JI Opt. Commun. PD SEP 15 PY 2000 VL 183 IS 5-6 BP 437 EP 443 DI 10.1016/S0030-4018(00)00884-1 PG 7 WC Optics SC Optics GA 355KK UT WOS:000089384700012 ER PT J AU Connerney, JEP Satoh, T AF Connerney, JEP Satoh, T TI The H-3(+) ion: a remote diagnostic of the jovian magnetosphere SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article; Proceedings Paper CT Discussion Meeting on Astronomy, Physics and Chemistry H-3(plus) CY FEB 09-10, 2000 CL ROYAL SOC LONDON, LONDON, ENGLAND HO ROYAL SOC LONDON DE infrared; H-3(+); magnetosphere; Jupiter; auroral; Io ID HUBBLE-SPACE-TELESCOPE; DECAMETRIC ARCS; POLAR AURORA; UV AURORA; FLUX TUBE; MU-M; JUPITER; EMISSIONS; H-3+; IMAGES AB Observations of the jovian system in the near-infrared (3.4 mu m) reveal a wealth of information about Jupiter's magnetic field, magnetosphere, and magnetospheric dynamics. This wavelength contains a few emission lines of the H-3(+) ion and it is centred on a deep methane absorption hand. As a result, one can image Jupiter's ionosphere at this wavelength with extraordinary signal-to-noise ratio, against a planet otherwise darkened by absorption due to methane in its atmosphere. High spatial resolution images of the planet's surface provide a synoptic view of the entire magnetosphere, fr-om the electrodynamics of Io and the torus, to the excitation of auroral displays at high magnetic latitude. Observations of the Io Flux Tube footprint have provided a new magnetic coordinate system for the jovian polar regions and new insight into the electrodynamic interaction between Jupiter and Io. Short-term temporal variations (days) of auroral intensity are observed in the IR and are well correlated with variations in the solar-wind ram pressure arriving at Jupiter. These H-3(+) emissions are thermally excited and are a good proxy for time-averaged energy deposition. It is now possible to produce detailed maps of energy deposition from the Io footprint (L = 6) to the pole, in which both system III and local time variations are evident. C1 NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Univ Tokyo, Frontier Res Ctr Computat Sci, Noda, Chiba 2788510, Japan. RP Connerney, JEP (reprint author), NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Code 695, Greenbelt, MD 20771 USA. RI connerney, john/I-5127-2013 NR 49 TC 29 Z9 29 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 SEP 15 PY 2000 VL 358 IS 1774 BP 2471 EP 2483 PG 13 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 359ZP UT WOS:000089642200016 ER PT J AU Millar, TJ Roberts, H Markwick, AJ Charnley, SB AF Millar, TJ Roberts, H Markwick, AJ Charnley, SB TI The role of H2D+ in the deuteration of interstellar molecules SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article; Proceedings Paper CT Discussion Meeting on Astronomy, Physics and Chemistry H-3(plus) CY FEB 09-10, 2000 CL ROYAL SOC LONDON, LONDON, ENGLAND HO ROYAL SOC LONDON DE interstellar; astrochemistry; deuterium ID DEUTERIUM FRACTIONATION; IONIZATION FRACTION; CLOUD CORES; CHEMISTRY; ABUNDANCE; TEMPERATURE; TMC-1; SPACE; GAS; HD AB Collisions between H-3(+) and HD in molecular clouds lead to the fractionation of deuterium in H2D+ at temperatures below 20 K. In this article, we describe the chemistry of H2D+ and discuss how variations in temperature and elemental abundances affect the level of fractionation in H2D+ and other species. We describe how accretion of gas-phase molecules on to cold dust grains enhances the deuteration in several molecules including doubly deuterated molecules. Mie show that the ion-neutral drift velocities attained in slow Alfven waves can destroy H2D+ in non-thermal reactions. As a result, the degree of fractionation can be reduced and we discuss observational consequences of such a model for the dark dust cloud TMC-1. C1 Univ Manchester, Inst Sci & Technol, Dept Phys, Manchester M60 1QD, Lancs, England. NASA, Div Space Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Millar, TJ (reprint author), Univ Manchester, Inst Sci & Technol, Dept Phys, POB 88, Manchester M60 1QD, Lancs, England. RI Charnley, Steven/C-9538-2012; OI Millar, Tom/0000-0001-5178-3656 NR 32 TC 30 Z9 30 U1 0 U2 2 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 SEP 15 PY 2000 VL 358 IS 1774 BP 2535 EP 2547 PG 13 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 359ZP UT WOS:000089642200024 ER PT J AU Larson, SL Hiscock, WA Hellings, RW AF Larson, SL Hiscock, WA Hellings, RW TI Sensitivity curves for spaceborne gravitational wave interferometers SO PHYSICAL REVIEW D LA English DT Article ID ANTENNA; RADIATION; LISA AB To determine whether particular sources of gravitational radiation will be detectable by a specific gravitational wave detector, it is necessary to know the sensitivity limits of the instrument. These instrumental sensitivities are often depicted (after averaging over source position and polarization) by graphing the minimal values of the gravitational wave amplitude detectable by the instrument versus the frequency of the gravitational wave. This paper describes in detail how to compute such a sensitivity curve given a set of specifications for a spaceborne laser interferometer gravitational wave observatory. Minor errors in the prior literature ore corrected, and the first (mostly) analytic calculation of the gravitational wave transfer function is presented. Example sensitivity curve calculations are presented for the proposed LISA interferometer. C1 Montana State Univ, Dept Phys, Bozeman, MT 59717 USA. Jet Prop Lab, Pasadena, CA 91103 USA. RP Larson, SL (reprint author), Montana State Univ, Dept Phys, Bozeman, MT 59717 USA. EM shane@physics.montana.edu; hiscock@montana.edu; hellings@graviton.jpl.nasa.gov RI Larson, Shane/E-8576-2010 NR 13 TC 107 Z9 108 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 SEP 15 PY 2000 VL 62 IS 6 AR 062001 DI 10.1103/PhysRevD.62.062001 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 354CB UT WOS:000089311300003 ER PT J AU Yen, AS Kim, SS Hecht, MH Frant, MS Murray, B AF Yen, AS Kim, SS Hecht, MH Frant, MS Murray, B TI Evidence that the reactivity of the martian soil is due to superoxide ions SO SCIENCE LA English DT Article ID OXIDE SURFACES; OXYGEN; PHOTOFORMATION; RESONANCE AB The Viking Landers were unable to detect evidence of Life on Mars but, instead, found a chemically reactive soil capable of decomposing organic molecules. This reactivity was attributed to the presence of one or more as-yet-unidentified inorganic superoxides or peroxides in the martian soil. Using electron paramagnetic resonance spectroscopy, we show that superoxide radical ions (O-2(-)) form directly on Mars-analog mineral surfaces exposed to ultraviolet radiation under a simulated martian atmosphere. These oxygen radicals can explain the reactive nature of the soil and the apparent absence of organic material at the martian surface. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Chemot Consulting, Newton, MA 02458 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. RP Yen, AS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 29 TC 162 Z9 166 U1 5 U2 33 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 SEP 15 PY 2000 VL 289 IS 5486 BP 1909 EP 1912 DI 10.1126/science.289.5486.1909 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 354XD UT WOS:000089355800038 PM 10988066 ER PT J AU Mangan, MA Lindsay, BG Stebbings, RF AF Mangan, MA Lindsay, BG Stebbings, RF TI Absolute partial cross sections for electron-impact ionization of CO from threshold to 1000 eV SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID MOLECULES; IONS; LIFETIMES; DETECTOR AB Absolute partial cross sections for electron-impact ionization of CO are reported far electron energies from threshold to 1000 eV. The product ions are mass analysed using a time-of-flight mass spectrometer and detected with a position-sensitive detector whose output unequivocally demonstrates that the various product ions are collected with equal efficiency irrespective of their initial kinetic energies. Data are presented for the production of CO+, C+, O+ and CO2+, and for the total cross section which is obtained as the sum of these partial cross sections. The overall uncertainty in the absolute cross section values is +/-5% for singly charged parent ions and +/-6% for fragment ions. Comparison is made with prior experiments and calculations. C1 Rice Univ, Dept Space Phys & Astron, Dept Phys, Houston, TX 77005 USA. Rice Univ, Rice Quantum Inst, Houston, TX 77005 USA. RP Mangan, MA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 183-601, Pasadena, CA 91109 USA. NR 29 TC 33 Z9 33 U1 1 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD SEP 14 PY 2000 VL 33 IS 17 BP 3225 EP 3234 DI 10.1088/0953-4075/33/17/305 PG 10 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 357YD UT WOS:000089529000011 ER PT J AU White, N AF White, N TI X-ray astronomy - Imaging black holes SO NATURE LA English DT Editorial Material ID ACCRETION DISK C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP White, N (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 3 TC 35 Z9 36 U1 0 U2 2 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD SEP 14 PY 2000 VL 407 IS 6801 BP 146 EP 147 DI 10.1038/35025179 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 352VX UT WOS:000089241000030 ER PT J AU Cash, W Shipley, A Osterman, S Joy, M AF Cash, W Shipley, A Osterman, S Joy, M TI Laboratory detection of X-ray fringes with a grazing-incidence interferometer SO NATURE LA English DT Article AB Starting with Galileo's observations of the Solar System, improvements of an order of magnitude in either the sensitivity or resolution of astronomical instruments have always brought revolutionary discoveries. The X-ray band of the spectrum, where exotic objects can have extremely high surface brightness(1), is ideally suited for significant improvements in imaging, but progress has been impeded by a lack of optics of sufficiently high sensitivity and quality. Here we present an X-ray interferometer design that is practical for adaptation to astronomical observatories. Our prototype interferometer, having just under one millimetre of baseline, creates fringes at 1.25 keV with an angular resolution of 100 milliarcseconds. With a larger version in orbit it will be possible to resolve X-ray sources at 10(-7) arcseconds, three orders of magnitude better than the finest-resolution images ever achieved on the sky (in the radio part of the spectrum) and over one million times better than the current best X-ray images. With such resolutions, we can study the environments of pulsars, resolve and then model relativistic blast waves, image material falling into a black hole, watch the physical formation of astrophysical jets, and study the dynamos of stellar coronae. C1 Univ Colorado, Boulder, CO 80309 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Cash, W (reprint author), Univ Colorado, Boulder, CO 80309 USA. NR 10 TC 72 Z9 73 U1 0 U2 9 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD SEP 14 PY 2000 VL 407 IS 6801 BP 160 EP 162 DI 10.1038/35025009 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 352VX UT WOS:000089241000039 ER PT J AU Marchenko, SV Rauw, G Antokhina, EA Antokhin, II Ballereau, D Chauville, J Corcoran, MF Costero, R Echevarria, J Eversberg, T Gayley, KG Koenigsberger, G Miroshnichenko, AS Moffat, AFJ Morrell, NI Morrison, ND Mulliss, CL Pittard, JM Stevens, IR Vreux, JM Zorec, J AF Marchenko, SV Rauw, G Antokhina, EA Antokhin, II Ballereau, D Chauville, J Corcoran, MF Costero, R Echevarria, J Eversberg, T Gayley, KG Koenigsberger, G Miroshnichenko, AS Moffat, AFJ Morrell, NI Morrison, ND Mulliss, CL Pittard, JM Stevens, IR Vreux, JM Zorec, J TI Coordinated monitoring of the eccentric O-star binary Iota Orionis: optical spectroscopy and photometry SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : general; stars : early-type; stars : general; stars : individual : Iota Orionis ID COLLIDING STELLAR WINDS; 29-UW CANIS-MAJORIS; X-RAY-EMISSION; CLOSE BINARY; SYSTEMS; SEARCH; MODEL; ATMOSPHERES; SPECTRUM; CURVES AB With the objective of investigating the wind-wind collision phenomenon and supporting contemporaneous X-ray observations, we have organized a large-scale, coordinated optical monitoring campaign of the massive, highly eccentric O9 III+B1 III binary Iota Orionis. Successfully separating the spectra of the components, we refine the orbital elements and confirm the rapid apsidal motion in the system. We also see strong interaction between the components during periastron passage and detect phase-locked variability in the spectrum of the secondary star. However, we find no unambiguous signs of the bow shock crashing on the surface of the secondary, despite the predictions of hydrodynamic simulations. Combining all available photometric data, we find rapid, phase-locked variations and model them numerically, thus restricting the orbital inclination to 50 degrees less than or similar to i less than or similar to 70 degrees. C1 Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada. Univ Montreal, Observ Mt Megant, Montreal, PQ H3C 3J7, Canada. Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. Moscow MV Lomonosov State Univ, Sternberg State Astron Inst, Moscow 119899, Russia. Observ Paris Meudon, DASGAL, UMR 8633, F-92125 Meudon, France. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Nacl Autonoma Mexico, Inst Astron, Morelia 58090, Michoacan, Mexico. Univ Iowa, Iowa City, IA 52245 USA. Univ Toledo, Ritter Observ, Toledo, OH 43606 USA. Observ La Plata, RA-1900 La Plata, Argentina. Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. Inst Astrophys, F-75014 Paris, France. RP Marchenko, SV (reprint author), Univ Montreal, Dept Phys, CP 6128,Succursale Centreville, Montreal, PQ H3C 3J7, Canada. OI Pittard, Julian/0000-0003-2244-5070 NR 45 TC 9 Z9 9 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 SEP 11 PY 2000 VL 317 IS 2 BP 333 EP 342 DI 10.1046/j.1365-8711.2000.03542.x PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 355TF UT WOS:000089401400013 ER PT J AU Gonthier, PL Harding, AK Baring, MG Costello, RM Mercer, CL AF Gonthier, PL Harding, AK Baring, MG Costello, RM Mercer, CL TI Compton scattering in ultrastrong magnetic fields: Numerical and analytical behavior in the relativistic regime SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : theory; magnetic fields; pulsars : general; radiation mechanisms : nonthermal; stars : neutron ID X-RAY PULSAR; SOFT GAMMA-REPEATERS; THOMSON SCATTERING; BURST SPECTRA; NEUTRON-STARS; POLAR GAPS; PHOTON; EMISSION; ABSORPTION; RADIATION AB This paper explores the effects of strong magnetic fields on the Compton scattering of relativistic electrons. Recent studies of upscattering and energy loss by relativistic electrons that have used the nonrelativistic, magnetic Thomson cross section for resonant scattering or the Klein-Nishina cross section for nonresonant scattering do not account for the relativistic quantum effects of strong fields (>4 x 10(12) G). We have derived a simplified expression for the exact QED scattering cross section for the broadly applicable case in which relativistic electrons move along the magnetic field. To facilitate applications to astrophysical models, we have also developed compact approximate expressions for both the differential and total polarization-dependent cross sections, with the latter representing well the exact total QED cross section even at the high fields believed to be present in environments near the stellar surfaces of soft gamma repeaters and anomalous X-ray pulsars. We find that strong magnetic fields significantly lower the Compton scattering cross section below and at the resonance when the incident photon energy exceeds m(e)c(2) in the electron rest frame. The cross section is strongly dependent on the polarization of the final scattered photon. Below the cyclotron fundamental, mostly photons of perpendicular polarization are produced in scatterings, a situation that also arises above this resonance for subcritical fields. However, an interesting discovery is that for supercritical fields, a preponderance of photons of parallel polarization results from scatterings above the cyclotron fundamental. This characteristic is both a relativistic and a magnetic effect not present in the Thomson or Klein-Nishina limits. C1 Hope Coll, Dept Phys, Holland, MI 49422 USA. NASA, Goddard Space Flight Ctr, Lab High Energy Astrophys, Greenbelt, MD 20771 USA. Coll Wooster, Dept Phys, Wooster, OH 44691 USA. Colorado Coll, Dept Phys, Colorado Springs, CO 80903 USA. RP Gonthier, PL (reprint author), Hope Coll, Dept Phys, 27 Graves Pl, Holland, MI 49422 USA. RI Harding, Alice/D-3160-2012 NR 51 TC 39 Z9 39 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2000 VL 540 IS 2 BP 907 EP 922 DI 10.1086/309357 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360DH UT WOS:000089650800025 ER PT J AU Allard, F Hauschildt, PH Schwenke, D AF Allard, F Hauschildt, PH Schwenke, D TI TiO and H2O absorption lines in cool stellar atmospheres SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : atmospheres ID LOW-MASS STARS; HOT-WATER VAPOR; MODEL ATMOSPHERES; PARALLEL IMPLEMENTATION; SPECTRA; GIANT; PROGRAM; DWARFS AB We compare the structures of model atmospheres and synthetic spectra calculated using different line lists for TiO and water vapor. We discuss the effects of different line list combinations on the model structures and spectra for both dwarf and giant stars. It is shown that recent improvements result in significantly improved spectra, in particular, in the optical where TiO bands are important. The water vapor-dominated near-infrared region remains problematic as the current water line lists do not yet completely reproduce the shapes of the observed spectra. We find that the AMES TiO list provides more opacity in most bands and that the new, smaller oscillator strengths lead to systematically cooler temperatures for early-type M dwarfs than previous models. These effects combine and will help to significantly improve the fits of models to observations in the optical as well as result in improved synthetic photometry of M stars. We show that the Davis, Littleton, & Phillips f(el)-values for the delta and phi bands of TiO best reproduce the observed V-l color indices. C1 Ecole Normale Super Lyon, CRAL, UML 5574, F-69364 Lyon 7, France. Univ Georgia, Dept Phys & Astron, Athens, GA 30602 USA. Univ Georgia, Ctr Simulat Phys, Athens, GA 30602 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Allard, F (reprint author), Ecole Normale Super Lyon, CRAL, UML 5574, F-69364 Lyon 7, France. OI Allard, France/0000-0003-1929-9340 NR 42 TC 133 Z9 133 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2000 VL 540 IS 2 BP 1005 EP 1015 DI 10.1086/309366 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360DH UT WOS:000089650800033 ER PT J AU Stothers, RB Chin, CW AF Stothers, RB Chin, CW TI A clue to the extent of convective mixing inside massive stars: The surface hydrogen abundances of luminous blue variables and hydrogen-poor Wolf-Rayet stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE convection; stars : evolution; stars : oscillations; stars : variables : other stars : Wolf-Rayet; supergiants ID RED SUPER-GIANTS; MAIN-SEQUENCE STARS; M-CIRCLE-DOT; LOSS RATES; STELLAR MODELS; O-STARS; FUNDAMENTAL PARAMETERS; THEORETICAL-MODELS; INHOMOGENEOUS STAR; SPECTRAL-ANALYSIS AB Interior layers of stars that have been exposed by surface mass loss reveal aspects of their chemical and convective histories that are otherwise inaccessible to observation. It must be significant that the surface hydrogen abundances of luminous blue variables (LBVs) show a remarkable uniformity, specifically X-surf = 0.3-0.4, while those of hydrogen-poor Wolf-Rayet (WN) stars fall, almost without exception, below these values, ranging down to X-surf = 0. According to our stellar model calculations, most LBVs are post-red-supergiant objects in a late blue phase of dynamical instability, and most hydrogen-poor WN stars are their immediate descendants. If this is so, stellar models constructed with the Schwarzschild (temperature-gradient) criterion for convection account well for the observed hydrogen abundances, whereas models built with the Ledoux (density-gradient) criterion fail. At the brightest luminosities, the observed hydrogen abundances of LBVs are too large to be explained by any of our highly evolved stellar models, but these LBVs may occupy transient blue loops that exist during an earlier phase of dynamical instability when the star first becomes a yellow supergiant. Independent evidence concerning the criterion for convection, which is based mostly on traditional color distributions of less massive supergiants on the Hertzsprung-Russell diagram, tends to favor the Ledoux criterion. It is quite possible that the true criterion for convection changes over from something like the Ledoux criterion to something like the Schwarzschild criterion as the stellar mass increases. 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 84 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2000 VL 540 IS 2 BP 1041 EP 1048 DI 10.1086/309349 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360DH UT WOS:000089650800035 ER PT J AU Woods, PM Kouveliotou, C van Paradijs, J Koshut, TM Finger, MH Briggs, MS Fishman, GJ Lewin, WHG AF Woods, PM Kouveliotou, C van Paradijs, J Koshut, TM Finger, MH Briggs, MS Fishman, GJ Lewin, WHG TI Detailed analysis of the pulsations during and after bursts from the bursting pulsar (GRO J1744-28) SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : individual (GRO J1744-28) stars : neutron; X-rays : bursts; X-rays : stars ID QUASI-PERIODIC OSCILLATIONS; RAPID BURSTER; SYSTEM AB The hard X-ray bursts observed during both major outbursts of the Bursting Pulsar (GRO J1744-28) show pulsations near the neutron star spin frequency with an enhanced amplitude relative to that of the persistent emission. Consistent with previous work, we find that the pulsations within bursts lag behind their expected arrival times based upon the persistent pulsar ephemeris. For an ensemble of 1293 bursts recorded with the Burst and Transient Source Experiment, the average burst pulse time delay (Delta t(FWHM)) is 61.0 +/- 0.8 ms in the 25-50 keV energy range and 72 +/- 5 ms in the 50-100 keV band. The residual time delay (Delta t(resid)) from 10 to 240 s following the start of the burst is 18.1 +/- 0.7 ms (25-50 keV). A significant correlation of the average burst time delay with burst peak flux is found. Our results are consistent with the model of the pulse time lags presented by Miller. C1 Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Univ Amsterdam, CHEAF, NL-1098 SJ Amsterdam, Netherlands. MIT, Dept Phys, Cambridge, MA 02138 USA. MIT, Ctr Space Res, Cambridge, MA 02138 USA. RP Woods, PM (reprint author), Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NR 25 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2000 VL 540 IS 2 BP 1062 EP 1068 DI 10.1086/309367 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360DH UT WOS:000089650800037 ER PT J AU Nakamura, R Fujii, Y Ishiguro, M Morishige, K Yokogawa, S Jenniskens, P Mukai, T AF Nakamura, R Fujii, Y Ishiguro, M Morishige, K Yokogawa, S Jenniskens, P Mukai, T TI The discovery of a faint glow of scattered sunlight from the dust trail of the Leonid parent comet 55p/Tempel-Tuttle SO ASTROPHYSICAL JOURNAL LA English DT Article DE comets : individual (55P/Tempel-Tuttle); dust, extinction interplanetary medium; meteors, meteoroids ID METEOR STREAM ACTIVITY; ZODIACAL DUST; SHOWER; SEARCH; STORMS; LIGHT AB A meteoric cloud is the faint glow of sunlight scattered by small meteoroids in the dust trail along the orbit of a comet as seen by an earthbound observer. While these clouds were previously only known from anecdotes of past meteor storms, we now report the detection of a meteoric cloud by modern techniques in the direction of the dust trail of comet 55P/Tempel-Tuttle, the parent of the Leonid meteor stream. Our photometric observations, performed on Mauna Kea, Hawaii, reveal the cloud as a local enhancement in sky brightness during the Leonid shower in 1998. The radius of the trail, deduced from the spatial extent of the cloud, is approximately 0.01 AU and is consistent with the spatial extent mapped out by historic accounts of meteor storms. The brightness of the cloud is approximately similar to 2%-3% of the background zodiacal light and cannot be explained by simple model calculations based on the zenith hourly rate and population index of the meteor stream in 1998. If the typical size of cloud particles is 10 mu m and the albedo is 0.1, the brightness translates into a number density of 1.2 x 10(-10) m(-3). The meteoroid cloud would be the product of the whole dust trail and not only the part that was crossed in 1998. C1 Kobe Univ, Informat Proc Ctr, Kobe, Hyogo 6578501, Japan. Kobe Univ, Grad Sch Sci & Technol, Kobe, Hyogo 6578501, Japan. Univ Tokyo, Grad Sch Sci, Tokyo 1138654, Japan. NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Nakamura, R (reprint author), Kobe Univ, Informat Proc Ctr, Kobe, Hyogo 6578501, Japan. NR 24 TC 18 Z9 18 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2000 VL 540 IS 2 BP 1172 EP 1176 DI 10.1086/309380 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360DH UT WOS:000089650800049 ER PT J AU Hollis, JM Lovas, FJ Jewell, PR AF Hollis, JM Lovas, FJ Jewell, PR TI Interstellar glycolaldehyde: The first sugar SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; ISM : clouds; ISM : individual (Sagittarius B2(N)); ISM : molecules; radio lines : ISM AB Interstellar glycolaldehyde (CH2OHCHO) has been detected in emission toward the Galactic center source Sagittarius B2(N) by means of millimeter-wave rotational transitions. Glycolaldehyde is an important biomarker since it is structurally the simplest member of the monosaccharide sugars that heretofore have gone undetected in interstellar clouds. There is no consensus as to how any such large complex molecules are formed in the interstellar clouds. It may be that the typical environment of dense interstellar clouds is favorable to glycolaldehyde synthesis by means of the polymerization of formaldehyde (H2CO) molecules either on grain surfaces or in the gas phase. Alternatively, we speculate that glycolaldehyde and other complex molecules may undergo assembly from functional molecular groups on grain surfaces. Utilizing common chemical precursors, a chance process could account for the high degree of isomerism observed in complex interstellar molecules (e.g., methyl formate, acetic acid, and glycolaldehyde). This work suggests that the phenomenon of isomerism be investigated further as a means of potentially constraining interstellar chemistry routes for those individual sources where the condition of good source-beam coupling can be achieved. C1 NASA, Goddard Space Flight Ctr, Space & Earth Data Comp Div, Greenbelt, MD 20771 USA. Univ Illinois, Dept Astron, Urbana, IL 61801 USA. Natl Radio Astron Observ, Green Bank, WV 24944 USA. RP Hollis, JM (reprint author), NASA, Goddard Space Flight Ctr, Space & Earth Data Comp Div, Code 930, Greenbelt, MD 20771 USA. NR 11 TC 212 Z9 214 U1 0 U2 22 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2000 VL 540 IS 2 BP L107 EP L110 DI 10.1086/312881 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360DJ UT WOS:000089650900011 ER PT J AU Pickett, BK Durisen, RH Cassen, P Mejia, AC AF Pickett, BK Durisen, RH Cassen, P Mejia, AC TI Protostellar disk instabilities and the formation of substellar companions SO ASTROPHYSICAL JOURNAL LA English DT Article DE hydrodynamics; instabilities; solar system : formation; stars : formation ID GIANT PLANETS; ACCRETION; EVOLUTION AB Recent numerical simulations of self-gravitating protostellar disks have suggested that gravitational instabilities can lead to the production of substellar companions. In these simulations, the disk is typically assumed to be locally isothermal; i.e., the initial, axisymmetric temperature in the disk remains everywhere unchanged. Such an idealized condition implies extremely efficient cooling for outwardly moving parcels of gas. While we have seen disk disruption in our own locally isothermal simulations of a small, massive protostellar disk, no long-lived companions formed as a result of the instabilities. Instead, thermal and tidal effects and the complex interactions of the disk material prevented permanent condensations from forming, despite the vigorous growth of spiral instabilities. In order to compare our results more directly with those of other authors, we here present three-dimensional evolutions of an older, larger, but less massive protostellar disk. We show that potentially long-lived condensations form only for the extreme of local isothermality, and then only when severe restrictions are placed on the natural tendency of the protostellar disk to expand in response to gravitational instabilities. A more realistic adiabatic evolution leads to vertical and radial expansion of the disk but no clump formation. We conclude that isothermal disk calculations cannot demonstrate companion formation by disk fragmentation but only suggest it at best. It will be necessary in future numerical work on this problem to treat the disk thermodynamics more realistically. C1 Valparaiso Univ, Neils Sci Ctr, Dept Phys & Astron, Valparaiso, IN 46383 USA. Indiana Univ, Dept Astron, Bloomington, IN 47405 USA. NASA, Ames Res Ctr, Moffett Field, CA 95035 USA. RP Pickett, BK (reprint author), Valparaiso Univ, Neils Sci Ctr, Dept Phys & Astron, Valparaiso, IN 46383 USA. EM brian.pickett@valpo.edu NR 17 TC 32 Z9 32 U1 0 U2 0 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 SEP 10 PY 2000 VL 540 IS 2 BP L95 EP L98 DI 10.1086/312884 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360DJ UT WOS:000089650900008 ER PT J AU Reames, DV AF Reames, DV TI Abundances of trans-iron elements in solar energetic particle events SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; shock waves; Sun : abundances; Sun : corona; Sun : flares; Sun : particle emission ID EVOLUTION; HE-3 AB We report the first comprehensive observation of the abundances of heavy elements of atomic number Z in the range 34 less than or equal to Z less than or equal to 82 in solar energetic particle (SEP) events as observed on the Wind spacecraft. In large gradual SEP events, abundances of the element groups 34 less than or equal to Z less than or equal to 40, 50 less than or equal to Z less than or equal to 56, and 70 less than or equal to Z less than or equal to 82, relative to Fe, are similar to corresponding coronal abundances within a factor of similar to 2 and vary little with time during the events. However, in sharp contrast, abundances of these ions from impulsive flares increase dramatically with Z so that abundances of Fe, 34 less than or equal to Z less than or equal to 40, and 50 less than or equal to Z less than or equal to 56, relative to O, are seen at similar to 10, similar to 100, and similar to 1000 times their coronal values, respectively. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Reames, DV (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. NR 15 TC 56 Z9 57 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2000 VL 540 IS 2 BP L111 EP L114 DI 10.1086/312886 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360DJ UT WOS:000089650900012 ER PT J AU Schwartz, DA Marshall, HL Lovell, JEJ Piner, BG Tingay, SJ Birkinshaw, M Chartas, G Elvis, M Feigelson, ED Ghosh, KK Harris, DE Hirabayashi, H Hooper, EJ Jauncey, DL Lanzetta, KM Mathur, S Preston, RA Tucker, WH Virani, S Wilkes, B Worrall, DM AF Schwartz, DA Marshall, HL Lovell, JEJ Piner, BG Tingay, SJ Birkinshaw, M Chartas, G Elvis, M Feigelson, ED Ghosh, KK Harris, DE Hirabayashi, H Hooper, EJ Jauncey, DL Lanzetta, KM Mathur, S Preston, RA Tucker, WH Virani, S Wilkes, B Worrall, DM TI Chandra discovery of a 100 kiloparsec X-ray jet in PKS 0637-752 SO ASTROPHYSICAL JOURNAL LA English DT Article DE quasars : individual (PKS 0637-752); radio continuum : galaxies; X-rays : galaxies ID VLBI OBSERVATIONS; RADIO-SOURCES AB The quasar PKS 0637-752, the first celestial X-ray target of the Chandra X-Ray Observatory, has revealed asymmetric X-ray structure extending from 3" to 12" west of the quasar, coincident with the inner portion of the jet previously detected in a 4.8 GHz radio image (Tingay et al. 1998). At a redshift of z = 0.651, the jet is the largest (greater than or similar to 100 kpc in the plane of the sky) and most luminous (similar to 10(44.6) ergs s(-1)) of the few so far detected in X-rays. This Letter presents a high-resolution X-ray image of the jet, from 42 ks of data when PKS 0637-752 was on-axis and ACIS-S was near the optimum focus. For the inner portion of the radio jet, the X-ray morphology closely matches that of new Australian Telescope Compact Array radio images at 4.8 and 8.6 GHz. Observations of the parsec-scale core using the very long baseline interferometry space observatory program mission show structure aligned with the X-ray jet, placing important constraints on the X-ray source models. Hubble Space Telescope images show that there are three small knots coincident with the peak radio and X-ray emission. Two of these are resolved, which we use to estimate the sizes of the X-ray and radio knots. The outer portion of the radio jet and a radio component to the east show no X-ray emission to a limit of about 100 times Lower flux. The X-ray emission is difficult to explain with models that successfully account for extranuclear X-ray/radio structures in other active galaxies. We think the most plausible is a synchrotron self-Compton model, but this would imply extreme departures from the conventional minimum energy and/or homogeneity assumptions. We also rule out synchrotron or thermal bremsstrahlung models for the jet X-rays, unless multicomponent or ad hoc geometries are invoked. C1 Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. MIT, Ctr Space Res, Cambridge, MA 02139 USA. CSIRO, Australia Telescope Natl Facil, Epping, NSW 2121, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Bristol, Dept Phys, Bristol BS8 1TL, Avon, England. Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. RP Schwartz, DA (reprint author), Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA. RI Tingay, Steven/B-5271-2013 NR 20 TC 85 Z9 85 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 10 PY 2000 VL 540 IS 2 BP L69 EP L72 DI 10.1086/312875 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360DJ UT WOS:000089650900002 ER PT J AU Realmuto, VJ Worden, HM AF Realmuto, VJ Worden, HM TI Impact of atmospheric water vapor on the thermal infrared remote sensing of volcanic sulfur dioxide emissions: A case study from the Pu'u 'O'o vent of Kilauea Volcano, Hawaii SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID MOUNT-ETNA; MT ETNA; SO2; ERUPTIONS; PLUMES; IMAGES; SPECTROSCOPY; ANTARCTICA; DATABASE; EDITION AB The December 18, 1999, launch of NASA's Terra satellite put two multispectral thermal infrared imaging instruments into Earth orbit. Experiments with airborne instruments have demonstrated that the data from such instruments can be used to detect volcanic SO2 plumes and clouds. However, one of the greatest challenges that will confront efforts to monitor volcanic SO2 emissions from space is the need to characterize the local atmosphere. In this paper we evaluate the sensitivity of the SO2 retrieval procedure to our knowledge of the local atmospheric conditions. We compare SO2 retrievals obtained with distant (radiosonde) and local (Fourier transform infrared (FTIR) soundings) atmospheric measurements and find that the relative difference is typically +/-25%. For ground temperature retrievals the relative difference is +/-1.5%. These results lead us to conclude that while local measurements of atmospheric conditions are preferable, useful retrievals can be obtained using atmospheric measurements from distant sites. In addition, we find very good agreement between SO2 and ground temperature retrievals obtained from thermal infrared imagery and FTIR soundings. C1 CALTECH, Jet Prop Lab, Visualizat & Earth Sci Applicat Grp, Pasadena, CA 91109 USA. RP Realmuto, VJ (reprint author), CALTECH, Jet Prop Lab, Visualizat & Earth Sci Applicat Grp, 4800 Oak Grove Dr,MS 168-514, Pasadena, CA 91109 USA. EM vince.realmuto@jpl.nasa.gov; helen.worden@jpl.nasa.gov NR 61 TC 26 Z9 26 U1 0 U2 2 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 SEP 10 PY 2000 VL 105 IS B9 BP 21497 EP 21507 DI 10.1029/2000JB900172 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 354NF UT WOS:000089336000015 ER PT J AU Ferguson, FT Nuth, JA AF Ferguson, FT Nuth, JA TI Experimental studies of the vapor phase nucleation of refractory compounds. V. The condensation of lithium SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID HOMOGENEOUS NUCLEATION; CESIUM VAPOR; SILVER; SIO AB Lithium nucleation was studied over the range of 830-1100 K in a gas evaporation apparatus yielding supersaturation ratios of approximately 300 to 7 over this temperature range, respectively, at an estimated flux of 10(9) cm(-3) s(-1). During runs we observed the same fluorescence phenomena due to atomic lithium vapor and the lithium dimer as noted by other researchers. The measured supersaturations are much higher than the values predicted by Classical Nucleation Theory. Modifications to Classical Nucleation Theory to account for the presence of dimers in the lithium vapor do not seem to account for this discrepancy. The data and Scaled Nucleation Theory agree fairly well at the lower temperature range, but at the higher end of the temperature range the data have a steeper drop in the supersaturation values than predicted by Scaled Nucleation Theory. (C) 2000 American Institute of Physics. [S0021-9606(00)01234-4]. C1 Catholic Univ Amer, Dept Chem, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ferguson, FT (reprint author), Catholic Univ Amer, Dept Chem, Washington, DC 20064 USA. RI Ferguson, Frank/C-9493-2012; Nuth, Joseph/E-7085-2012 NR 28 TC 15 Z9 15 U1 1 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 8 PY 2000 VL 113 IS 10 BP 4093 EP 4102 DI 10.1063/1.1288148 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 349GC UT WOS:000089034900020 ER PT J AU Hammond, TG Benes, E O'Reilly, KC Wolf, DA Linnehan, RM Taher, A Kaysen, JH Allen, PL Goodwin, TJ AF Hammond, TG Benes, E O'Reilly, KC Wolf, DA Linnehan, RM Taher, A Kaysen, JH Allen, PL Goodwin, TJ TI Mechanical culture conditions effect gene expression: gravity-induced changes on the space shuttle SO PHYSIOLOGICAL GENOMICS LA English DT Article DE renal cells; cell culture; gene array; flow cytometry; vitamin D receptor ID SHEAR-STRESS; MICROGRAVITY; FERMENTATION; MICROARRAY; TISSUES; FLOW; RNA AB Three-dimensional suspension culture is a gravity-limited phenomenon. The balancing forces necessary to keep the aggregates in suspension increase directly with aggregate size. This leads to a self-propagating cycle of cell damage by balancing forces. Cell culture in microgravity avoids this trade-off. We determined which genes mediate three-dimensional culture of cell and tissue aggregates in the low-shear stress, low-turbulent environment of actual microgravity. Primary cultures of human renal cortical cells were flown on the space shuttle. Cells grown in microgravity and ground-based controls were grown for 6 days and fixed. RNA was extracted, and automated gene array analysis of the expression of 10,000 genes was performed. A select group of genes were regulated in microgravity. These 1,632 genes were independent of known shear stress response element-dependent genes and heat shock proteins. Specific transcription factors underwent large changes in microgravity including the Wilms' tumor zinc finger protein, and the vitamin D receptor. A specific group of genes, under the control of defined transcription factors, mediate three-dimensional suspension culture under microgravity conditions. C1 Tulane Univ, Med Ctr, Sch Med,Ctr Bioenvironm Res, Tulane Vet Affairs Environm Astrobiol Ctr, New Orleans, LA 70112 USA. Tulane Univ, Med Ctr, Sch Med, Dept Med,Nephrol Sect SL 45, New Orleans, LA 70112 USA. Vet Affairs Med Ctr, New Orleans, LA USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Hammond, TG (reprint author), Tulane Univ, Med Ctr, Sch Med,Ctr Bioenvironm Res, Tulane Vet Affairs Environm Astrobiol Ctr, 1430 Tulane Ave, New Orleans, LA 70112 USA. FU NCRR NIH HHS [R21-RR-12645] NR 21 TC 84 Z9 90 U1 3 U2 13 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 1094-8341 J9 PHYSIOL GENOMICS JI Physiol. Genomics PD SEP 8 PY 2000 VL 3 IS 3 BP 163 EP 173 PG 11 WC Cell Biology; Genetics & Heredity; Physiology SC Cell Biology; Genetics & Heredity; Physiology GA 351RV UT WOS:000089172700006 PM 11015612 ER PT J AU Des Marais, DJ AF Des Marais, DJ TI Evolution - When did photosynthesis emerge on earth? SO SCIENCE LA English DT Editorial Material ID BIOGEOCHEMICAL CARBON-CYCLE; WESTERN-AUSTRALIA; OXYGENIC PHOTOSYNTHESIS; STROMATOLITES; GA C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Des Marais, DJ (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 29 TC 147 Z9 153 U1 4 U2 46 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 SEP 8 PY 2000 VL 289 IS 5485 BP 1703 EP 1705 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 352BT UT WOS:000089195200034 ER PT J AU Showman, AP Dowling, TE AF Showman, AP Dowling, TE TI Nonlinear simulations of Jupiter's 5-micron hot spots SO SCIENCE LA English DT Article ID GALILEO PROBE; CLOUD STRUCTURE; ATMOSPHERIC COMPOSITION; WATER-VAPOR; ABUNDANCE; WAVES; SHOEMAKER-LEVY-9; DOWNDRAFTS; ORIGIN AB Large-scale nonlinear simulations of Jupiter's 5-micron hot spots produce Long-lived coherent structures that cause subsidence in local regions, explaining the Low cloudiness and the dryness measured by the Galileo probe inside a hot spot. Like observed hot spots, the simulated coherent structures are equatorially confined, have periodic spacing, propagate west relative to the flow, are generally confined to one hemisphere, and have an anticyclonic gyre on their equatorward side, The southern edge of the simulated hot spots develops vertical shear of up to 70 meters per second in the eastward wind, which can explain the results of the Galileo probe Doppler wind experiment. C1 NASA, Ames Res Ctr, Natl Res Council, Moffett Field, CA 94035 USA. Univ Louisville, Comparat Planetol Lab, Louisville, KY 40292 USA. RP Showman, AP (reprint author), NASA, Ames Res Ctr, Natl Res Council, Mail Stop 245-3, Moffett Field, CA 94035 USA. RI Dowling, Timothy/J-4537-2013 OI Dowling, Timothy/0000-0002-7400-2274 NR 30 TC 68 Z9 68 U1 1 U2 2 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 SEP 8 PY 2000 VL 289 IS 5485 BP 1737 EP 1740 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 352BT UT WOS:000089195200042 PM 10976064 ER PT J AU Yaoi, T Laksanalamai, P Jiemjit, A Kagawa, HK Alton, T Trent, JD AF Yaoi, T Laksanalamai, P Jiemjit, A Kagawa, HK Alton, T Trent, JD TI Cloning and characterization of ftsZ and pyrF from the archaeon Thermoplasma acidophilum SO BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS LA English DT Article DE cell division; archaea; genetics; cytoskeleton; molecular evolution ID ARCHAEBACTERIUM SULFOLOBUS-ACIDOCALDARIUS; BACTERIAL-CELL-DIVISION; RIBOSOMAL-RNA GENES; ESCHERICHIA-COLI; NUCLEOTIDE-SEQUENCE; OROTIDINE-5'-PHOSPHATE DECARBOXYLASE; PYRIMIDINE BIOSYNTHESIS; COENZYME SPECIFICITY; THERMUS-THERMOPHILUS; 5-FLUOROOROTIC ACID AB To characterize cytoskeletal components of archaea, the ftsZ gene from Thermoplasma acidophilum was cloned and sequenced. In T. acidophilum ftsZ, which is involved in cell division, was found to be in an operon with the pyrF gene, which encodes orotidine-5'-monophosphate decarboxylase (ODC), an essential enzyme in pyrimidine biosynthesis, Both ftsZ; and pyrF from T. acidophilum were expressed in Escherichia coli and formed functional proteins. FtsZ expression in wild-type E. coli resulted in the filamentous phenotype characteristic of ftsZ mutants. T, acidophilum pyrF expression in an E, coli mutant lacking pyrF complemented the mutation and rescued the strain. Sequence alignments of ODCs from archaea, bacteria, and eukarya reveal five conserved regions, two of which have homology to 3-hexulose-6-phosphate synthase (HPS), suggesting a common substrate recognition and binding motif, (C) 2000 Academic Press. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Santa Cruz, Dept Chem & Biochem, Santa Cruz, CA 95064 USA. Western Illinois Univ, Dept Biol Sci, Macomb, IL 61455 USA. SETI Inst, Mt View, CA 94043 USA. RP Trent, JD (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 53 TC 10 Z9 12 U1 0 U2 5 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0006-291X J9 BIOCHEM BIOPH RES CO JI Biochem. Biophys. Res. Commun. PD SEP 7 PY 2000 VL 275 IS 3 BP 936 EP 945 DI 10.1006/bbrc.2000.3401 PG 10 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA 353FV UT WOS:000089264900038 PM 10973825 ER PT J AU Powell, JA Neudeck, PG Trunek, AJ Beheim, GM Matus, LG Hoffman, RW Keys, LJ AF Powell, JA Neudeck, PG Trunek, AJ Beheim, GM Matus, LG Hoffman, RW Keys, LJ TI Growth of step-free surfaces on device-size (0001)SiC mesas SO APPLIED PHYSICS LETTERS LA English DT Article AB It is believed that atomic-scale surface steps cause defects in single-crystal films grown heteroepitaxially on SiC substrates. A method is described whereby surface steps can be grown out of existence on arrays of device-size mesas on commercial "on-axis" SiC wafers. Step-free mesas with dimensions up to 200 mu m square have been produced on 4H-SiC wafers and up to 50 mu m square on a 6H-SiC wafer. A limiting factor in scaling up the size and yield of the step-free mesas is the density of screw dislocations in the SiC wafers. The fundamental significance of this work is that it demonstrates that two-dimensional nucleation of SiC can be suppressed while carrying out step-flow growth on (0001)SiC. The application of this method should enable the realization of improved heteroepitaxially-grown SiC and GaN device structures. (C) 2000 American Institute of Physics. [S0003-6951(00)02636-X]. C1 NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH 44135 USA. RP Powell, JA (reprint author), NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. NR 10 TC 88 Z9 88 U1 2 U2 13 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD SEP 4 PY 2000 VL 77 IS 10 BP 1449 EP 1451 DI 10.1063/1.1290717 PG 3 WC Physics, Applied SC Physics GA 348ZT UT WOS:000089017200013 ER PT J AU Canedy, CL Aggarwal, S Li, H Venkatesan, T Ramesh, R Van Keuls, FW Romanofsky, RR Miranda, FA AF Canedy, CL Aggarwal, S Li, H Venkatesan, T Ramesh, R Van Keuls, FW Romanofsky, RR Miranda, FA TI Structural and dielectric properties of epitaxial Ba1-xSrxTiO3/Bi4Ti3O12/ZrO2 heterostructures grown on silicon SO APPLIED PHYSICS LETTERS LA English DT Article ID TITANATE THIN-FILMS; PHASE SHIFTERS; CAPACITORS AB We report on the dielectric properties of an epitaxial heterostructure comprised of Ba1-xSrxTiO3, Bi4Ti3O12, and (ZrO2)(0.91)(Y2O3)(0.09) grown on silicon substrates for potential use in microwave devices. Careful x-ray analysis indicates crystallographic alignment of all layers and transmission electron microscopy and Auger analysis reveals high quality epitaxy with minimal interdiffusion. The viability of using such heterostructures in actual microwave devices was assessed by incorporating the films in a coupled microstripline phase shifter design. The phase shifter devices, operating in the Ku band, had losses of less than 4 dB with a maximum phase shift of nearly 40 degrees at 40 V. We compare this performance with a (Ba, Sr)TIO3/MgO phase shifter. These results presented represent significant progress towards integrating ferroelectric films with conventional silicon technology. (C) 2000 American Institute of Physics. [S0003-6951(00)03336-2]. C1 Univ Maryland, Mat Res Sci & Engn Ctr, College Pk, MD 20742 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Canedy, CL (reprint author), Univ Maryland, Mat Res Sci & Engn Ctr, College Pk, MD 20742 USA. RI Venkatesan, Thirumalai/E-1667-2013 NR 19 TC 30 Z9 31 U1 0 U2 7 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD SEP 4 PY 2000 VL 77 IS 10 BP 1523 EP 1525 DI 10.1063/1.1290724 PG 3 WC Physics, Applied SC Physics GA 348ZT UT WOS:000089017200038 ER PT J AU Northam, GB Rivers, HK AF Northam, GB Rivers, HK TI IC engine applications of carbon-carbon SO ADVANCED ENGINEERING MATERIALS LA English DT Article AB Many of the properties of carbon-carbon make it an ideal material for reciprocating materials of intermittent combustion (IC) engines. Recent diesel engine tests, shown herein, indicate that the thermal and mechanical properties of carbon-carbon are adequate for piston applications. However, reducing the manufacturing costs and providing long term oxidation protection are still issues that need to be addressed. C1 Creat Tech Solut Inc, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Northam, GB (reprint author), Creat Tech Solut Inc, 30 Res Dr, Hampton, VA 23666 USA. NR 15 TC 1 Z9 2 U1 1 U2 1 PU WILEY-V C H VERLAG GMBH PI BERLIN PA MUHLENSTRASSE 33-34, D-13187 BERLIN, GERMANY SN 1438-1656 J9 ADV ENG MATER JI Adv. Eng. Mater. PD SEP PY 2000 VL 2 IS 9 BP 583 EP 586 PG 4 WC Materials Science, Multidisciplinary SC Materials Science GA 357VX UT WOS:000089522400015 ER PT J AU Singer, BA Lockard, DP Brentner, KS AF Singer, BA Lockard, DP Brentner, KS TI Computational aeroacoustic analysis of slat trailing-edge flow SO AIAA JOURNAL LA English DT Article ID FLAP AB An acoustic analysis based on the Ffowcs Williams and Hawkings equation (Ffowcs Williams, J. E,, and Hawkings, D. L,, "Sound Generated by Turbulence and Surfaces in Arbitrary Motion," Philosophical Transactions of the Royal Society of London, Vol. A264, No. 1151, 1969, pp, 321-342) was performed for a high-lift system. As input, the acoustic analysis used unsteady how data obtained from a highly resolved, time-dependent, Reynolds-averaged Navier-Stokes calculation. The analysis strongly suggests that vortex shedding from the trailing edge of the slat results in a high-amplitude, high-frequency acoustic signal similar to that which was observed in a corresponding experimental study of the high-lift system. C1 NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. RP Singer, BA (reprint author), NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. NR 22 TC 27 Z9 28 U1 2 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 2000 VL 38 IS 9 BP 1558 EP 1564 DI 10.2514/2.1177 PG 7 WC Engineering, Aerospace SC Engineering GA 350AE UT WOS:000089077400008 ER PT J AU Hixon, R AF Hixon, R TI Numerically consistent strong conservation grid motion for finite difference schemes SO AIAA JOURNAL LA English DT Article ID RUNGE-KUTTA SCHEMES; COMPUTATIONAL ACOUSTICS; LOW-DISSIPATION; SIMULATIONS; EQUATIONS; FLOW AB An investigation into the numerical issues of curvilinear coordinate grid motion for finite difference schemes is performed. Several formulations of the time-dependent curvilinear coordinate equations are compared using unsteady benchmark test problems. A new, numerically consistent method of computing the unsteady grid metrics for the strong conservation equations Is developed and demonstrated. C1 NASA, John H Glenn Res Ctr, Inst Computat Mech Prop, Cleveland, OH 44135 USA. RP Hixon, R (reprint author), NASA, John H Glenn Res Ctr, Inst Computat Mech Prop, Cleveland, OH 44135 USA. NR 14 TC 5 Z9 5 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 2000 VL 38 IS 9 BP 1586 EP 1593 DI 10.2514/2.1141 PG 8 WC Engineering, Aerospace SC Engineering GA 350AE UT WOS:000089077400012 ER PT J AU Edwards, JR Franklin, RK Liou, MS AF Edwards, JR Franklin, RK Liou, MS TI Low-diffusion flux-splitting methods for real fluid flows with phase transitions SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA 14th Computational Fluid Dynamics Conference CY JUN 28-JUL 01, 1999 CL NORFOLK, VIRGINIA SP Amer Inst Aeronaut & Astronaut ID RIEMANN SOLVER; SCHEME; CAVITATION; EQUATIONS; SPEEDS; STATE AB Methods for extending the AUSM+ low-diffusion flux-splitting scheme toward the calculation of real fluid flows Pt all speeds are presented, The single-phase behavior of the fluid is defined by the Sanchez-Lacombe equation of state (Sanchez, I. C,, and Lacombe, R. H., "An Elementary Molecular Theory of Classical Fluids: Pure Fluids," Journal of Physical Chemistry, Vol, 80, No. 21, 1976, pp, 2352-2362), a lattice-fluid description. Liquid-vapor phase transitions are modeled through a homogeneous equilibrium approach. Time-derivative preconditioning is utilized to allow effective integration of the equation system at all Row speeds and all states of compressibility, Modifications to the preconditioned variant of AUSM+ necessary to preserve solution accuracy under such renditions are presented in detail. One-dimensional results are presented for the faucet problem, a classic test case for multifluid algorithms, as well as for liquid octane flow through a converging-diverging nozzle, Two-dimensional calculations are presented for water flow over a hemisphere/cylinder geometry and liquid carbon dioxide how through a capillary nozzle, The results illustrate the effectiveness of the flux-splitting scheme in capturing such multiphase flow features as cavitation zones and vapor-liquid condensation shocks, as well as incompressible liquid and compressible vapor responses, within the framework of a single numerical algorithm. C1 N Carolina State Univ, Dept Mech & Aerosp Engn, Raleigh, NC 27695 USA. NASA, John H Glenn Res Ctr, Turbomachinery & Prop Syst Div, Cleveland, OH 44135 USA. RP Edwards, JR (reprint author), N Carolina State Univ, Dept Mech & Aerosp Engn, Campus Box 7910, Raleigh, NC 27695 USA. NR 41 TC 64 Z9 68 U1 0 U2 7 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 2000 VL 38 IS 9 BP 1624 EP 1633 DI 10.2514/2.1145 PG 10 WC Engineering, Aerospace SC Engineering GA 350AE UT WOS:000089077400016 ER PT J AU Shebalin, JV AF Shebalin, JV TI Motion in a microgravity environment SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA 37th Aerospace Sciences Meeting and Exhibit CY JAN 11-14, 1999 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut AB The microgravity environment inside a space station in circular orbit around the Earth is described. The linear equations of motion of a freely falling test particle in a space station under the influence of gravity gradient and atmospheric drag is explicitly determined. These equations are solved for some simple cases, with the idealized assumption of constant drag, to produce a qualitative description of the motion of a test particle over an orbital period. C1 NASA, Lyndon B Johnson Space Ctr, Int Space Stn Payloads Off, Houston, TX 77058 USA. RP Shebalin, JV (reprint author), NASA, Lyndon B Johnson Space Ctr, Int Space Stn Payloads Off, Mail Code OZ, Houston, TX 77058 USA. NR 13 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD SEP PY 2000 VL 38 IS 9 BP 1656 EP 1658 DI 10.2514/2.1150 PG 3 WC Engineering, Aerospace SC Engineering GA 350AE UT WOS:000089077400020 ER PT J AU Angotti, CM Chan, WT Sample, CJ Levine, MS AF Angotti, CM Chan, WT Sample, CJ Levine, MS TI Combined dietary and exercise intervention for control of serum cholesterol in the workplace SO AMERICAN JOURNAL OF HEALTH PROMOTION LA English DT Article DE diet; exercise; intervention; cardiovascular risk ID LOW-FAT DIET; CARDIOVASCULAR RISK; PHYSICAL-ACTIVITY; MEN; WOMEN; FITNESS; DISEASE AB Purpose. To elucidate a potential combined dietary and exercise intervention affect on cardiovascular risk reduction of the National Aeronautics and Space Administration Headquarters employees. Design. A nonexperimental, longitudinal, clinical-chart review study (1987 to 1996) of an identified intervention group and a reference (not a control) group. Setting. The study group worked in an office environment and participated in the annual medical examinations. Subjects. An intervention group of 858 people with initially elevated serum cholesterol, and a reference group of 963 people randomly sampled from 10 % of the study group. Measures. Serum cholesterol data were obtained for both groups, respectively, from pre- and postintervention and annual examinations. The reference group was adjusted by statistical exclusion of potential intervention participants. Regression equations (cholesterol vs. study years) for the unadjusted/adjusted reference groups were tested for statistical significance. Intervention. An 8-week individualized, combined dietary and exercise program was instituted with annual follow-ups and was repeated where warranted. Results. Only the unadjusted (but not the adjusted) reference group with initial mean total serum cholesterol levels above 200 mg/dL shows a significant 9-year decline trend and significant beta coefficient tests. An intervention effect is suggested. Mean high density lipoprotein cholesterol rose slightly in the intervention group but was maintained in the reference group. Conclusion. With potential design limitations, the NASA intervention program focusing on a high risk group may be associated to some degree, if not fully, with an overall cardiovascular risk profile improvement. C1 NASA Headquarters, Off Hlth Affairs, Washington, DC 20546 USA. Uniformed Serv Univ Hlth Sci, Dept Prevent Med & Biometr, Bethesda, MD 20814 USA. NASA, Div Aerosp Med & Occupat Hlth, Washington, DC 20546 USA. RP Angotti, CM (reprint author), NASA Headquarters, Off Hlth Affairs, Mail Code UH,300E St SW, Washington, DC 20546 USA. NR 21 TC 6 Z9 6 U1 0 U2 2 PU AMER J HEALTH PROMOTION INC PI KEEGO HARBOR PA 1660 CASS LAKE RD, STE 104, KEEGO HARBOR, MI 48320 USA SN 0890-1171 J9 AM J HEALTH PROMOT JI Am. J. Health Promot. PD SEP-OCT PY 2000 VL 15 IS 1 BP 9 EP 16 PG 8 WC Public, Environmental & Occupational Health SC Public, Environmental & Occupational Health GA 362DB UT WOS:000089762400003 PM 11184120 ER PT J AU Ku, YTE Montgomery, LD Lee, HC Luna, B Webbon, BW AF Ku, YTE Montgomery, LD Lee, HC Luna, B Webbon, BW TI Physiologic and functional responses of MS patients to body cooling SO AMERICAN JOURNAL OF PHYSICAL MEDICINE & REHABILITATION LA English DT Article DE multiple sclerosis; cooling therapy; thermal stress; rehabilitation ID MULTIPLE-SCLEROSIS; SYMPTOMATIC TREATMENT; TEMPERATURE AB Objective: The objective of this study was to compare the responses of multiple sclerosis (MS) patients to short-term cooling therapy using three different vest configurations. Design: Each garment was used to cool 13 male and 13 female MS subjects (31-67 yr). Oral and right and left ear temperatures were logged manually every 5 min. Arm, leg, chest, and rectal temperatures, heart rate, and respiration were recorded continuously on a Biolog ambulatory monitor. Each subject was given a series of subjective and objective evaluation tests before and after cooling. Results: The Life Enhancement Technologies and Steele vests test groups had similar, significant (P < 0.01) cooling effects on oral and ear canal temperatures, which decreased approximately 0.4 degrees C and 0.3 degrees C, respectively. The Life Enhancement Technologies active liquid cooling vest produced the coldest (P < 0.01) skin temperature and provided the most improvement on subjective and objective performance measures. Conclusions: These results show that the various garment configurations tested do not produce similar thermal responses in all MS patients. The circulating liquid cooling vest was found to be more effective than either of the two passive cooling garments tested. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Lockheed Martin Engn & Sci, Moffett Field, CA USA. RP Ku, YTE (reprint author), NASA, Ames Res Ctr, Mail Stop 236-5, Moffett Field, CA 94035 USA. NR 16 TC 12 Z9 12 U1 2 U2 8 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0894-9115 J9 AM J PHYS MED REHAB JI Am. J. Phys. Med. Rehabil. PD SEP-OCT PY 2000 VL 79 IS 5 BP 427 EP 434 DI 10.1097/00002060-200009000-00004 PG 8 WC Rehabilitation; Sport Sciences SC Rehabilitation; Sport Sciences GA 354GK UT WOS:000089321200004 PM 10994884 ER PT J AU Greenleaf, JE Petersen, TW Gabrielsen, A Pump, B Bie, P Christensen, NJ Warberg, J Videbaek, R Simonson, SR Norsk, P AF Greenleaf, JE Petersen, TW Gabrielsen, A Pump, B Bie, P Christensen, NJ Warberg, J Videbaek, R Simonson, SR Norsk, P TI Low LBNP tolerance in men is associated with attenuated activation of the renin-angiotensin system SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE hypotensive tolerance; vasopressin; central venous pressure; catecholamines ID BODY NEGATIVE-PRESSURE; HEAD-UP TILT; CONSCIOUS DOGS; ORTHOSTATIC INTOLERANCE; BLOOD-PRESSURE; HUMANS; VASOPRESSIN; NOREPINEPHRINE; ENDOTHELIN-1; HYPOTENSION AB Plasma vasoactive hormone concentrations [epinephrine (p(Epi)), norepinephrine (p(NE)), ANG II (p(ANG II)), vasopressin (p(VP)), endothelin-1 (p(ET-1))] and plasma renin activity (p(RA)) were measured periodically and compared during lower body negative pressure (LBNP) to test the hypothesis that responsiveness of the renin-angiotensin system, the latter being one of the most powerful vasoconstrictors in the body, is of major importance for LBNP tolerance. Healthy men on a controlled diet (2,822 cal/day, 2 mmol . kg(-1) . day(-1) Na+) were exposed to 30 min of LBNP from -15 to -50 mmHg. LBNP was uneventful for seven men [25 +/- 2 yr, high-tolerance (HiTol) group], but eight men (26 +/- 3 yr) reached presyncope after 11 +/- 1 min [P < 0.001, low-tolerance (LoTol) group]. Mean arterial pressure (MAP) did not change measurably, but central venous pressure and left atrial diameter decreased similarly in both groups (5-6 mmHg, by approximate to 30%, P < 0.05). Control (0 mmHg LBNP) hormone concentrations were similar between groups, however, pRA differed between them (LoTol 0.6 +/- 0.1, HiTol 1.2 +/- 0.1 ng ANG I . ml(-1) . h(-1), P < 0.05). LBNP increased (P < 0.05) p(RA) and p(ANG II), respectively, more in the HiTol group (9.9 +/- 2.2 ng ANG I . ml(-1) . h(-1) and 58 +/- 12 pg/ml) than in LoTol subjects (4.3 +/- 0.9 ng ANG I . ml(-1) . h(-1) and 28 +/- 6 pg/ml). In contrast, the increase in p(VP) was higher (P < 0.05) in the LoTol than in the HiTol group. The increases (P < 0.05) for p(NE) were nonsignificant between groups, and p(ET-1) remained unchanged. Thus there may be a causal relationship between attenuated activation of p(RA) and p(ANG II) and presyncope, with p(VP) being a possible cofactor. Measurement of resting p(RA) may be of predictive value for those with lower hypotensive tolerance. C1 Rigshosp, Danish Aerosp Med Ctr Res & Clin Aviat Med, DK-2200 Copenhagen, Denmark. Univ So Denmark, Dept Physiol & Pharmacol, DK-5000 Odense, Denmark. Herlev Hosp, Dept Internal Med & Endocrinol, DK-2730 Herlev, Denmark. RP Greenleaf, JE (reprint author), NASA, Ames Res Ctr, Gravitat Res Branch 221A2, Moffett Field, CA 94035 USA. NR 24 TC 38 Z9 38 U1 0 U2 2 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 SEP PY 2000 VL 279 IS 3 BP R822 EP R829 PG 8 WC Physiology SC Physiology GA 347CP UT WOS:000088910100010 PM 10956239 ER PT J AU Thrasher, TN Keil, LC AF Thrasher, TN Keil, LC TI Systolic pressure predicts plasma vasopressin responses to hemorrhage and vena caval constriction in dogs SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE antidiuretic hormone; arterial baroreceptors; cardiac receptors; atrial receptors; ventricular receptors; blood volume; blood pressure ID CONSCIOUS DOGS; ARTERIAL BARORECEPTORS; RENIN; RECEPTORS; SECRETION; CORTISOL; BLOCKADE; DRINKING; RELEASE; HEART AB We have proposed that the reflex increase in arginine vasopressin (AVP) secretion in response to hypovolemia is due to arterial baroreceptor unloading. If arterial pressure is the key to the mechanism, the slope relating plasma AVP to arterial pressure should be the same in response to hemorrhage, a model of true hypovolemia, and in response to thoracic inferior vena caval constriction (IVCC), a model of central hypovolemia. We tested this hypothesis in conscious, chronically instrumented dogs (n = 8). The mean coefficient of determination (r(2)) values obtained from the individual regressions of log AVP onto systolic pressure (SP) and mean arterial pressure (MAP) in response to hemorrhage were 0.953 +/- 0.009 and 0.845 +/- 0.047, respectively. Paired comparisons indicated a significant difference between the means (P< 0.05), hence, SP was used in subsequent analyses. The mean slopes relating the log of plasma AVP to SP in response to hemorrhage and IVCC were -0.034 +/- 0.003 and -0.032 +/- 0.002, respectively, and the means were not significantly different (P = 0.7). The slopes were not altered when the experiments were repeated during acute blockade of cardiac receptors by intrapericardial procaine. Finally, sinoaortic denervation (n = 4) markedly reduced the slope in both the hemorrhage and IVCC treatments. We conclude that baroreceptors monitoring arterial pressure provide the principal reflex control of AVP secretion in response to hypovolemia. C1 Univ Maryland, Dept Surg, Baltimore, MD 21201 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Thrasher, TN (reprint author), Univ Maryland, Dept Surg, 10 S Pine St,Rm 400, Baltimore, MD 21201 USA. FU NHLBI NIH HHS [HL-41313] NR 28 TC 16 Z9 17 U1 1 U2 2 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 SEP PY 2000 VL 279 IS 3 BP R1035 EP R1042 PG 8 WC Physiology SC Physiology GA 347CP UT WOS:000088910100034 PM 10956263 ER PT J AU Stone, M Ladd, SL Gabrieli, JDE AF Stone, M Ladd, SL Gabrieli, JDE TI The role of selective attention in perceptual and affective priming SO AMERICAN JOURNAL OF PSYCHOLOGY LA English DT Article ID WORD-FRAGMENT COMPLETION; AFFECTIVE DISCRIMINATION; EXPLICIT MEMORY; AFFECTIVE JUDGMENTS; DIVIDED ATTENTION; IMPLICIT MEMORY; GLOBAL AMNESIA; STIMULI; TESTS; EXPOSURE AB Two kinds of perceptual priming (word identification and word fragment completion), as well as preference priming (that may rely on special affective mechanisms) were examined after participants either read or named the colors of words and nonwords at study. Participants named the colors of words more slowly than the colors of nonwords, indicating that lexical processing of the words occurred at study. Nonetheless, priming on all three tests was lower after color naming than after reading, despite evidence of lexical processing during color naming shown by slower responses to words than to nonwords. These results indicate that selective attention to (rather than the mere processing of) letter string identity at study is important for subsequent repetition priming. C1 Stanford Univ, Dept Psychol, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. W Valley Coll, Saratoga, CA 95070 USA. RP Gabrieli, JDE (reprint author), Stanford Univ, Dept Psychol, Jordan Hall, Stanford, CA 94305 USA. FU NIA NIH HHS [5 F32 AG05616] NR 60 TC 23 Z9 23 U1 1 U2 4 PU UNIV ILLINOIS PRESS PI CHAMPAIGN PA 1325 S OAK ST, CHAMPAIGN, IL 61820 USA SN 0002-9556 J9 AM J PSYCHOL JI Am. J. Psychol. PD FAL PY 2000 VL 113 IS 3 BP 341 EP 358 DI 10.2307/1423363 PG 18 WC Psychology, Multidisciplinary SC Psychology GA 351TT UT WOS:000089174800002 PM 10997232 ER PT J AU Ozawa, K Tsapin, AI Nealson, KH Cusanovich, MA Akutsu, H AF Ozawa, K Tsapin, AI Nealson, KH Cusanovich, MA Akutsu, H TI Expression of a tetraheme protein, Desulfovibrio vulgaris miyazaki F cytochrome c(3), in Shewanella oneidensis MR-1 SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID GENE ENCODING CYTOCHROME-C3; ESCHERICHIA-COLI; HILDENBOROUGH; PURIFICATION; PUTREFACIENS; REDUCTION; CLONING AB Cytochrome c(3) from Desulfovibrio vulgaris Miyazaki F was successfully expressed in the facultative aerobe Shewanella oneidensis MR-1 under anaerobic, microaerophilic, and aerobic conditions, with yields of 0.3 to 11.5 mg of cytochrome/g of cells. A derivative of the broad-host-range plasmid pRK-115 containing the cytochrome c(3) gene from D. vulgaris Miyazaki F was used for transformation of S. oneidensis MR-1, resulting in the production of protein product that was indistinguishable from that produced by D. vulgaris Miyazaki F, except for the presence of one extra alanine residue at the N terminus. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Yokohama Natl Univ, Fac Engn, Dept Chem & Biotechnol, Hodogaya Ku, Yokohama, Kanagawa 2408501, Japan. Univ Arizona, Dept Biochem, Tucson, AZ 85721 USA. RP Nealson, KH (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 26 Z9 26 U1 5 U2 8 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 SEP PY 2000 VL 66 IS 9 BP 4168 EP 4171 DI 10.1128/AEM.66.9.4168-4171.2000 PG 4 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 350NZ UT WOS:000089109200078 PM 10966450 ER PT J AU Erickson, EF Rabanus, D AF Erickson, EF Rabanus, D TI Beam shape effects on grating spectrometer resolution SO APPLIED OPTICS LA English DT Article AB The collimated optical beam in a grating spectrometer may be circular or elliptical in cross section, so that different parts of the beam illuminate different numbers of grooves on the grating. Here we estimate the consequent loss in spectral resolution relative to that obtained with a beam that illuminates a fixed number of grooves. The effect reduces the intrinsic resolving power of the spectrometer by similar to 15%, exclusive of other contributions such as finite entrance-slit width. (C) 2000 Optical Society of America OCIS codes: 050.1940, 050.1950. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. German Aerosp Ctr Space Sensors & Planetary Explo, D-12489 Berlin, Germany. RP Erickson, EF (reprint author), NASA, Ames Res Ctr, MS 245-6, Moffett Field, CA 94035 USA. EM erickson@cygnus.arc.nasa.gov NR 4 TC 2 Z9 2 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 SEP 1 PY 2000 VL 39 IS 25 BP 4486 EP 4489 DI 10.1364/AO.39.004486 PG 4 WC Optics SC Optics GA 349BT UT WOS:000089024500003 PM 18350035 ER PT J AU Ohl, RG Saha, TT Friedman, SD Barkhouser, RH Moos, HW AF Ohl, RG Saha, TT Friedman, SD Barkhouser, RH Moos, HW TI Imaging performance of telescope mirrors for far-ultraviolet astronomy SO APPLIED OPTICS LA English DT Article ID SPECTROSCOPIC EXPLORER FUSE; SILICON-CARBIDE; COATINGS AB We describe image testing, surface metrology, and modeling of telescope mirrors (0.5 m in diameter, f/4.3) for the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. Laboratory image testing of wavelengths in the visible, vacuum, and midultraviolet validated a theoretical analysis by use of the Optical Surface Analysis Code (OSAC). Our modeling is based on surface metrology, including measurements of figure, midfrequency error, and microroughness. This combination of metrology, out-of-band performance testing, and modeling verified that the mirrors would meet mission requirements. We use OSAC to predict the FUSE telescope's far-ultraviolet (90-120-nm) point-spread function and assess its effect on instrument efficiency. The mirrors have a 90% encircled energy diameter of 1.5 arc sec at lambda = 100 nm. Including the effects of spacecraft pointing error, the mirrors have a predicted average slit transmission at lambda = 100 nm of approximately 87% and 96% for the 1.25- and Q-arc sec-wide spectrograph slits, respectively, where the required transmissions are 50% and 95%. (C) 2000 Optical Society of America OCIS codes: 110.6770, 120.4800, 220.4840, 260.7210, 120.3940, 110.2960. C1 Johns Hopkins Univ, Ctr Astrophys Sci, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ohl, RG (reprint author), Johns Hopkins Univ, Ctr Astrophys Sci, Dept Phys & Astron, Baltimore, MD 21218 USA. EM Raymond.G.Ohl@gsfc.nasa.gov NR 34 TC 1 Z9 1 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 SEP 1 PY 2000 VL 39 IS 25 BP 4513 EP 4523 DI 10.1364/AO.39.004513 PG 11 WC Optics SC Optics GA 349BT UT WOS:000089024500006 PM 18350038 ER PT J AU Cavallo, RM Nagar, NM AF Cavallo, RM Nagar, NM TI Aluminum abundances, deep mixing, and the blue-tail second-parameter effect in the globular clusters M3 and M13 SO ASTRONOMICAL JOURNAL LA English DT Review DE globular clusters : individual (M3, M13); stars : abundances; stars : horizontal-branch; stars : late-type; stars : Population II ID RED GIANT STARS; SOLAR IRON ABUNDANCE; THERMONUCLEAR REACTION-RATES; FE-I LINES; PROTON CAPTURE CHAINS; POOR HALO FIELD; HORIZONTAL-BRANCH; OXYGEN ABUNDANCES; NITROGEN ABUNDANCES; OSCILLATOR-STRENGTHS AB We analyze high-resolution, high signal-to-noise ratio spectra of six red giant branch (RGB) stars in the globular cluster M3 (NGC 5272) and three in M13 (NGC 6205) that were obtained with the 4 m Mayall Telescope and echelle spectrometer on Kitt Peak. The spectra include lines of O, Na, Mg, Al, Si, Ca, Ti, V, Mn, Fe, and Ni. We also analyze the [AI/Fe] values of 96 RGB stars in M13 covering the brightest 3.5 mag, which include 66 measurements that were derived from moderate-resolution, low signal-to-noise ratio spectra obtained with the WIYN 3.5 m telescope and Hydra multiobject spectrograph, also on Kitt Peak. In addition, we compile from the literature and inspect the [Na/Fe] values of 119 RGB stars in M13. We test for bimodality in the [AI/Fe] and [Na/Fe] distributions using the KMM algorithm and find that the [AI/Fe] values in M13 are distributed bimodally at all points along the RGB that were observed, while the [Na/Fe] values are bimodal only over the brightest 2 mag. The ratios of Al-enhanced to Al-normal and Na-enhanced to Na-normal giants increase toward the tip of the RGB in M13, which is suggestive of deep mixing in this cluster. The limited M3 data exhibit a bimodal distribution of [Al/Fe] values and are suggestive of no deep mixing; however, they are too few to be conclusive. We further test for a relationship between deep mixing on the RGB and a second parameter that can create the extended blue tail seen along the horizontal branches of some clusters by using an "instantaneous" mixing algorithm, which we develop here. We conclude that the data for both clusters are consistent with deep mixing as a "blue-tail second parameter," and we suggest future observations to further constrain the results. Finally, we offer a solution to the problem of overproducing sodium during deep mixing that is based on the depletion of Ne-22 in asymptotic giant branch stars and suggest that pollution might best be traced by s-process elements in the Sr-Y-Zr peak. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. EM rob@shemesh.gsfc.nasa.gov OI Cavallo, Robert/0000-0002-7696-3650 NR 108 TC 44 Z9 44 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 SEP PY 2000 VL 120 IS 3 BP 1364 EP 1383 DI 10.1086/301515 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360LX UT WOS:000089670300016 ER PT J AU Garmire, G Feigelson, ED Broos, P Hillenbrand, LA Pravdo, SH Townsley, L Tsuboi, Y AF Garmire, G Feigelson, ED Broos, P Hillenbrand, LA Pravdo, SH Townsley, L Tsuboi, Y TI Chandra X-Ray Observatory study of the Orion Nebula cluster and BN/KL region SO ASTRONOMICAL JOURNAL LA English DT Article DE infrared radiation; ISM : individual (Orion Nebula); stars : activity; stars : pre-main-sequence; X-rays ID T-TAURI STARS; YOUNG STELLAR OBJECTS; I DARK CLOUD; MOLECULAR CLOUD; RADIO-EMISSION; ROSAT; TRAPEZIUM; POPULATION; EXTINCTION; CORE AB About 1000 X-ray emitting young pre-main-sequence (PMS) stars distributed in mass from similar to 0.05 M. brown dwarfs to a similar to 50 M. O star are detected in an image of the Orion Nebula obtained with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory. This is the richest field of sources ever obtained in X-ray astronomy. Individual X-ray luminosities in the Orion Nebula cluster range from the sensitivity limit of 2 x 10(28) ergs s(-1) to similar to 10(32) ergs s(-1). ACIS sources include 85%-90% of V < 20 stars, plus a lower but substantial fraction of deeply embedded stars with extinctions as high as A(V) similar or equal to 60. The relationships between X-ray and other PMS stellar properties suggest that X-ray luminosity of lower-mass PMS stars depends more on mass, and possibly stellar rotation, than on bolometric luminosity, as widely reported. In a subsample of 17 unabsorbed stars with mass similar or equal to 1 M., X-ray luminosities are constant at a high level around L-x similar or equal to 2 x 10(30) ergs s(-1) for the first similar or equal to 2 Myr while descending the convective Hayashi track, but diverge during the 2-10 Myr phase with X-ray emission plummeting in some stars but remaining high in others. This behavior is consistent with the distribution of X-ray luminosities on the zero-age main sequence and with current theories of their rotational history and magnetic dynamos. The sources in the Becklin-Neugebauer/Kleinman-low region of massive star formation are discussed in detail. They include both unabsorbed and embedded low-mass members of the Orion Nebula cluster, the luminous infrared Source n, and a class of sources without optical or infrared counterparts that may be new magnetically active embedded PMS stars. Several X-ray sources are also variable radio emitters, an association often seen in magnetically active PMS stars. Faint X-ray emission is seen close to, but apparently not coincident with, the Becklin-Neugebauer object. Its nature is not clear. C1 Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA. CALTECH, Dept Astron, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Garmire, G (reprint author), Penn State Univ, Dept Astron & Astrophys, 525 Davey Lab, University Pk, PA 16802 USA. NR 58 TC 105 Z9 105 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 2000 VL 120 IS 3 BP 1426 EP 1435 DI 10.1086/301523 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360LX UT WOS:000089670300020 ER PT J AU Wolf-Chase, GA Barsony, M O'Linger, J AF Wolf-Chase, GA Barsony, M O'Linger, J TI Giant molecular outflows powered by protostars in L1448 SO ASTRONOMICAL JOURNAL LA English DT Article DE ISM : individual (L1448); ISM : jets and outflows; ISM : kinematics and dynamics methods : observational; stars : formation ID HERBIG-HARO OBJECTS; BIPOLAR OUTFLOW; OPHIUCHI CLOUD; IMAGING SURVEY; DARK CLOUDS; JET; CO; L-1448; FLOWS; ENERGETICS AB We present sensitive (T*(R) approximate to 0.1 K), large-scale (47' x 7'-corresponding to 4 pc x 0.6 pc at the source) maps of the CO J = 1-->0 emission of the L1448 dark cloud at 55 " resolution. These maps were acquired using the on-the-fly (OTF) capability of the NRAO 12 m telescope atop Kitt Peak in Arizona. CO outflow activity is seen in L1448 on parsec scales for the first time. Careful comparison of the spatial and velocity distribution of our high-velocity CO maps with previously published optical and near-infrared images and spectra has led to the identification of six distinct CO outflows. Three of these are powered by the Class 0 protostars, L1448C, L1448N(A), and L1448N(B). L1448 IRS 2 is the source of two more outflows, one of which is newly identified from our maps. The sixth newly discovered outflow is powered by an as yet unidentified source outside of our map boundaries. We show the direct link between the heretofore unknown, giant, highly collimated, protostellar molecular outflows and their previously discovered, distant optical manifestations. The outflows traced by our CO mapping generally reach the projected cloud boundaries. Integrated intensity maps over narrow velocity intervals indicate there is significant overlap of blue- and redshifted gas, suggesting the outflows are highly inclined with respect to the line of sight, although the individual outflow position angles are significantly different. The velocity channel maps also show that the outflows dominate the CO Line cores as well as the high-velocity wings. The magnitude of the combined flow momenta, as well as the combined kinetic energy of the flows, are sufficient to disperse the 50 M. NH3 cores in which the protostars are currently forming, although some question remains as to the exact processes involved in redirecting the directionality of the outflow momenta to effect the complete dispersal of the parent cloud. C1 Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Adler Planetarium & Astron Museum, Chicago, IL 60605 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wolf-Chase, GA (reprint author), Univ Chicago, Dept Astron & Astrophys, 5640 S Ellis Ave, Chicago, IL 60637 USA. NR 42 TC 32 Z9 32 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD SEP PY 2000 VL 120 IS 3 BP 1467 EP 1478 DI 10.1086/301535 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 360LX UT WOS:000089670300023 ER PT J AU Bulik, T Kluzniak, W Zhang, W AF Bulik, T Kluzniak, W Zhang, W TI Kilohertz QPOs, the marginally stable orbit, and the mass of the central sources - a maximum likelihood test SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : binaries : general; stars : oscillations; X-rays : stars ID NEUTRON STAR STRUCTURE; RADIO PULSARS; EVOLUTION; MATTER; X-2 AB Kilohertz quasi perodic oscillations (QPOs) have been detected in more than a dozen LMXBs. We show that the observations are consistent with the assumption that the maximum-frequency QPOs occur in the innermost (marginally) stable orbit allowed by general relativity. On this assumption, taking the masses of the compact objects to be randomly distributed in some interval, we use the maximum likelihood method to determine the minimum and maximum mass in the parent distribution of kHz QPO sources. At the 99% confidence level, we find the mass range of the accreting compact objects to be (1.55 M., 2.40 M.), in remarkable agreement with the expected mass range of neutron stars in LMXBs. C1 Copernicus Astron Ctr, PL-00716 Warsaw, Poland. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Bulik, T (reprint author), Copernicus Astron Ctr, Bartycka 18, PL-00716 Warsaw, Poland. EM bulik@camk.edu.pl RI Zhang, William/D-3535-2012 NR 47 TC 6 Z9 6 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 SEP PY 2000 VL 361 IS 1 BP 153 EP 158 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 357PT UT WOS:000089510600021 ER PT J AU Moehler, S Landsman, WB Dorman, B AF Moehler, S Landsman, WB Dorman, B TI Blue horizontal branch stars in metal-rich globular clusters - II. 47 Tucanae and NGC 362 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : early-type; stars : horizontal-branch; stars : Population II; Galaxy : globular clusters : individual : NGC 104, NGC 362 ID SMALL-MAGELLANIC-CLOUD; EVOLVED STELLAR POPULATIONS; RELATIVE PROPER MOTIONS; ULTRAVIOLET-RADIATION; OUTER REGIONS; HOT STARS; PHOTOMETRY; PARAMETERS; 47-TUCANAE; PARALLAXES AB Atmospheric parameters (T-eff, log g), and radial velocities are derived for twelve candidate blue horizontal branch (HB) stars in the globular clusters 47 Tuc and NGC 362, which so far have been known to contain primarily red HE stars. The spectroscopic targets were selected from the catalog of hot stars detected in these clusters at 1600 Angstrom using the Ultraviolet Imaging Telescope (UIT). Spectroscopic analyses of these stars reveal, however, that one of the four HE candidates targets in 47 Tuc, and five out of the eight targets in NGC 362 are probably background stars belonging to the Small Magellanic Cloud. With the exception of the photometric binary MJ38529 in 47 Tuc, the parameters of those stars that are probable members of 47 Tuc and NGC 362 agree well with canonical HE : evolution. The three hot stars in 47 Tuc all have 10,000 K < T-eff < 15,000 K and include one photometric binary, which suggests that they might have a different physical origin than the dominant red HE population. The somewhat cooler blue HE stars in NGC 362 show more continuity with the dominant red HE population and might simply arise from red giants with unusually high mass loss. C1 Univ Erlangen Nurnberg, Astron Inst, Dr Remeis Sternwarte, D-96049 Bamberg, Germany. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20770 USA. RP Moehler, S (reprint author), Univ Erlangen Nurnberg, Astron Inst, Dr Remeis Sternwarte, Sternwartstr 7, D-96049 Bamberg, Germany. EM ai13@sternwarte.uni-erlangen.de; landsman@mpb.gsfc.nasa.gov; dorman@veris.gsfc.nasa.gov NR 46 TC 13 Z9 13 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 SEP PY 2000 VL 361 IS 3 BP 937 EP 944 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369XG UT WOS:000165092600019 ER PT J AU Johansson, S Zethson, T Hartman, H Ekberg, JO Ishibashi, K Davidson, K Gull, T AF Johansson, S Zethson, T Hartman, H Ekberg, JO Ishibashi, K Davidson, K Gull, T TI New forbidden and fluorescent FeIII lines identified in HST spectra of eta Carinae SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE atomic processes; line : identification; stars : individual : eta Car; stars : variables : general; ultraviolet : stars ID TRANSITION-PROBABILITIES; FE-III; STAR; EJECTA AB We discuss the origin of eight emission lines in the spectra of gas blobs close to the central star of eta Carinae. The spectra have been obtained with the Goddard High Resolution Spectrograph (GHRS) and the Space Telescope Imaging Spectrograph (STIS) onboard the Hubble Space Telescope. Between 2400 and 2500 Angstrom five narrow lines are identified as new forbidden lines of doubly ionized iron, [Fe III]. We present gA-value data for the corresponding transitions, which combine two different metastable configurations of Fe III. An anomalous intensity of the narrow Fe III line (UV 34) at 1914 Angstrom is explained as fluorescence due to HLy alpha pumping. A level mixing of about 1% increases the f-value of the pumped excitation channel by more than two orders of magnitude, which makes the pumping efficient and the fluorescence significant. We introduce a new designation for fluorescence lines photoexcited by an accidental resonance, eg. (Fe III) in the case of doubly ionized iron. C1 Univ Lund, Dept Phys, S-22100 Lund, Sweden. Univ Minnesota, Dept Astron, Minneapolis, MN 55455 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Johansson, S (reprint author), Univ Lund, Dept Phys, POB 118, S-22100 Lund, Sweden. EM sveneric.johansson@fysik.lu.se; torgil.zethson@fysik.lu.se; henrik.hartman@fysik.lu.se; jan_olof.ekberg@fysik.lu.se; bish@howdy.gsfc.nasa.gov; kd@ea.spa.umn.edu; gull@sea.gsfc.nasa.gov RI Gull, Theodore/D-2753-2012; Hartman, Henrik/K-3113-2013 OI Gull, Theodore/0000-0002-6851-5380; NR 21 TC 39 Z9 39 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 SEP PY 2000 VL 361 IS 3 BP 977 EP 981 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369XG UT WOS:000165092600023 ER PT J AU Tokarev, YV Kaiser, ML Boiko, GN Gustov, PV AF Tokarev, YV Kaiser, ML Boiko, GN Gustov, PV TI Anisotropy of the hectometer cosmic radio background SO ASTRONOMY LETTERS-A JOURNAL OF ASTRONOMY AND SPACE ASTROPHYSICS LA English DT Article DE Galaxy (Milky Way system) AB The angular anisotropy of cosmic radio emission at frequencies of 260, 512, 772, and 1028 kHz was studied on the WIND spacecraft when it moved to a distance of similar to 1.5 x 10(6) km from the Earth at the deepest phase of the last solar minimum. The modulation index of the temperature of the spacecraft dipole antenna rotating in the plane of the ecliptic was found to have an indistinct frequency dependence with a maximum of 17% near 500 kHz. This result modifies significantly the conclusions of the only similar experiment on the IMP-6 spacecraft carried out under less favorable observing conditions. Existing ideas about the causes of the radio-background anisotropy in the opacity region of the Galactic gas disk are briefly reviewed. (C) 2000 MAIK "Nauka/Interperiodica". C1 Nizhni Novgorod State Univ, Radiophys Res Inst, Nizhnii Novgorod 603600, Russia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Tokarev, YV (reprint author), Nizhni Novgorod State Univ, Radiophys Res Inst, Ul Lyadova 25-14,GSP-51, Nizhnii Novgorod 603600, Russia. NR 9 TC 2 Z9 2 U1 0 U2 1 PU MAIK NAUKA/INTERPERIODICA PUBL PI MELVILLE PA C/O AMERICAN INST PHYSICS, 2 HUNTINGTON QUANDRANGLE, STE 1NO1, MELVILLE, NY 11747-4502 USA SN 1063-7737 J9 ASTRON LETT+ JI Astron. Lett.-J. Astron. Space Astrophys. PD SEP PY 2000 VL 26 IS 9 BP 553 EP 557 DI 10.1134/1.1307888 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356ZG UT WOS:000089473600001 ER PT J AU McKernan, B Carson, MJ Yaqoob, T Fegan, DJ AF McKernan, B Carson, MJ Yaqoob, T Fegan, DJ TI Short timescale variability in the broadband emission of the blazars Mkn421 and Mkn501 SO ASTROPARTICLE PHYSICS LA English DT Article ID ACTIVE GALAXY MARKARIAN-421; TEV PHOTONS; GAMMA-RAYS; SPECTRUM; SEARCH AB We analyse ASCA satellite X-ray data and Whipple Observatory TeV gamma-ray data from the Blazars Mkn421 and Mkn501 for short timescale variability using the excess pair fraction method. We discuss the method and the data as well as EPF sensitivity to these data. We find that in these data sets, we can rule out an amplitude of variability greater than 10% on timescales less than 10 min from both sources and at both wavelengths at a confidence level of >99.7%. We discuss briefly the implications of low amplitudes of variability on short timescales for the beamed jet of relativistic particles probably producing these radiations and, we del ive limits from the data on the local percentage change in both the lepton density and the magnetic field strength in these Blazar jets. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Coll Dublin, Dept Phys, Dublin 4, Ireland. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP McKernan, B (reprint author), Univ Coll Dublin, Dept Phys, Dublin 4, Ireland. OI Carson, Michael/0000-0003-0400-7819 NR 20 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-6505 J9 ASTROPART PHYS JI Astropart Phys. PD SEP PY 2000 VL 14 IS 2 BP 131 EP 140 DI 10.1016/S0927-6505(00)00107-9 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 354AN UT WOS:000089307800007 ER PT J AU Sahu, KC Vreeswijk, P Bakos, G Menzies, JW Bragaglia, A Frontera, F Piro, L Albrow, MD Bond, IA Bower, R Caldwell, JAR Castro-Tirado, AJ Courbin, F Dominik, M Fynbo, JU Galama, T Glazebrook, K Greenhill, J Gorosabel, J Hearnshaw, J Hill, K Hjorth, J Kane, S Kilmartin, PM Kouveliotou, C Martin, R Masetti, N Maxted, P Minniti, D Moller, P Muraki, Y Nakamura, T Noda, S Ohnishi, K Palazzi, E van Paradijs, J Pian, E Pollard, KR Rattenbury, NJ Reid, M Rol, E Saito, T Sackett, PD Saizar, P Tinney, C Vermaak, P Watson, R Williams, A Yock, P Dar, A AF Sahu, KC Vreeswijk, P Bakos, G Menzies, JW Bragaglia, A Frontera, F Piro, L Albrow, MD Bond, IA Bower, R Caldwell, JAR Castro-Tirado, AJ Courbin, F Dominik, M Fynbo, JU Galama, T Glazebrook, K Greenhill, J Gorosabel, J Hearnshaw, J Hill, K Hjorth, J Kane, S Kilmartin, PM Kouveliotou, C Martin, R Masetti, N Maxted, P Minniti, D Moller, P Muraki, Y Nakamura, T Noda, S Ohnishi, K Palazzi, E van Paradijs, J Pian, E Pollard, KR Rattenbury, NJ Reid, M Rol, E Saito, T Sackett, PD Saizar, P Tinney, C Vermaak, P Watson, R Williams, A Yock, P Dar, A TI Discovery of the optical counterpart and early optical observations of GRB 990712 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; gamma rays : bursts ID GAMMA-RAY BURST; HUBBLE-SPACE-TELESCOPE; 28 FEBRUARY 1997; 25 APRIL 1998; ERROR BOX; AFTERGLOW; SUPERNOVA; GALAXY; GRB-970508; EMISSION AB We present the discovery observations of the optical counterpart of the gamma-ray burst GRB 990712 taken 4.16 hr after the outburst and discuss its light curve observed in the V, R, and I bands during the first similar to 35 days after the outburst. The observed light curves were fitted with a power-law decay for the optical transient (OT), plus an additional component that was treated in two different ways. First, the additional component was assumed to be an underlying galaxy of constant brightness. The resulting slope of the decay is 0.97(-0.02)(+0.05), and the magnitudes of the underlying galaxy are V = 22.3 +/- 0.05, R = 21.75 +/- 0.05, and I = 21.35 +/- 0.05. Second, the additional component was assumed to be a galaxy plus an underlying supernova with a time-variable brightness identical to that of GRB 980425, appropriately scaled to the redshift of GRB 990712. The resulting slope of the decay is similar, but the goodness of fit is worse, which would imply that either this GRB is not associated with an underlying supernova or the underlying supernova is much fainter than the supernova associated with GRB 980425. The galaxy in this case is fainter: V = 22.7 +/- 0.05, R = 22.25 +/- 0.05, and I = 22.15 +/- 0.05, and the OT plus the underlying supernova at a given time is brighter. Measurements of the brightnesses of the OT and the galaxy by late-time Hubble Space Telescope observation and ground-based observations can thus assess the presence of an underlying supernova. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Konkoly Observ Budapest, H-1525 Budapest, Hungary. Univ Bologna, Inst TeSRE, I-40127 Bologna, Italy. S African Astron Observ, ZA-7935 Cape Town, South Africa. Osservatorio Astron Bologna, I-40127 Bologna, Italy. CNR, Ist Astrofis Spaziale, Rome, Italy. Univ Canterbury, Dept Phys & Astron, Christchurch 1, New Zealand. Univ Auckland, Fac Sci, Auckland 1, New Zealand. Univ Durham, Dept Phys, Durham DH1 3LE, England. INTA, LAEFF, Madrid 28080, Spain. CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain. Pontificia Univ Catolica Chile, Dept Astron, Santiago 22, Chile. Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. Aarhus Univ, Inst Phys & Astron, DK-8000 Aarhus C, Denmark. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. Anglo Australian Observ, Epping, NSW 2121, Australia. Univ Tasmania, Dept Phys, Hobart, Tas 7001, Australia. Univ Copenhagen, Astron Observ, DK-2100 Copenhagen, Denmark. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. Perth Observ, Perth, WA 6076, Australia. Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. European So Observ, D-85748 Garching, Germany. Nagoya Univ, Solar Terr Environm Lab, Chikusa Ku, Nagoya, Aichi 4648601, Japan. Kyoto Univ, Yukawa Inst, Kyoto, Japan. Nagano Natl Coll Technol, Nagano, Japan. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Victoria Univ Wellington, Dept Phys, Wellington, New Zealand. Tokyo Metropolitan Coll Aeronaut, Tokyo, Japan. Lincoln Univ Coll, Buenos Aires, DF, Argentina. Technion Israel Inst Technol, Dept Phys, IL-32000 Haifa, Israel. Technion Israel Inst Technol, Space Res Inst, IL-32000 Haifa, Israel. RP Sahu, KC (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. EM ksahu@stsci.edu RI Greenhill, John/C-8367-2013; Williams, Andrew/K-2931-2013; Galama, Titus/D-1429-2014; PIRO, LUIGI/E-4954-2013; Hjorth, Jens/M-5787-2014; Glazebrook, Karl/N-3488-2015; Palazzi, Eliana/N-4746-2015; Bragaglia, Angela/O-9397-2015; OI Williams, Andrew/0000-0001-9080-0105; Galama, Titus/0000-0002-1036-396X; PIRO, LUIGI/0000-0003-4159-3984; Hjorth, Jens/0000-0002-4571-2306; Glazebrook, Karl/0000-0002-3254-9044; Bragaglia, Angela/0000-0002-0338-7883; Palazzi, Eliana/0000-0002-8691-7666; Castro-Tirado, A. J./0000-0003-2999-3563; Tinney, Christopher/0000-0002-7595-0970; Pian, Elena/0000-0001-8646-4858 NR 42 TC 41 Z9 41 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 SEP 1 PY 2000 VL 540 IS 1 BP 74 EP 80 DI 10.1086/309340 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356CW UT WOS:000089427600009 ER PT J AU Wallace, PM Griffis, NJ Bertsch, DL Hartman, RC Thompson, DJ Kniffen, DA Bloom, SD AF Wallace, PM Griffis, NJ Bertsch, DL Hartman, RC Thompson, DJ Kniffen, DA Bloom, SD TI A systematic search for short-term variability of EGRET sources SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : observations ID GAMMA-RAY EMISSION; SOURCE 2CG-135+01; GALACTIC-CENTER; RADIO-SOURCES; 3C-279; PLANE; FLARE; MHZ AB The Third EGRET Catalog of High-Energy Gamma-Ray Sources contains 170 unidentified sources, and there is great interest in the nature of these sources. One means of determining source class is the study of flux variability on timescales of days; pulsars are believed to be stable on these timescales, while blazars are known to be highly variable. In addition, previous work has demonstrated that 3EG JO241-6103 and 3EG J1837-0606 are candidates for a new gamma-ray source class. These sources near the Galactic plane display transient behavior but cannot be associated with any known blazars. Although many instances of flaring active galactic nuclei have been reported, the EGRET database has not been systematically searched for occurrences of short-timescale (similar to 1 day) variability. These considerations have led us to conduct a systematic search for short-term variability in EGRET data, covering all viewing periods through proposal cycle 4. Six 3EG catalog sources are reported here to display variability on short timescales; four of them are unidentified. In addition, three noncatalog variable sources are discussed. C1 Berry Coll, Dept Phys & Astron, Mt Berry, GA 30149 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Hampden Sydney Coll, Dept Phys & Astron, Hampden Sydney, VA 23943 USA. CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. RP Wallace, PM (reprint author), Berry Coll, Dept Phys & Astron, Mt Berry, GA 30149 USA. RI Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 38 TC 30 Z9 31 U1 0 U2 0 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 SEP 1 PY 2000 VL 540 IS 1 BP 184 EP 191 DI 10.1086/309325 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356CW UT WOS:000089427600019 ER PT J AU Ellison, DC Berezhko, EG Baring, MG AF Ellison, DC Berezhko, EG Baring, MG TI Nonlinear shock acceleration and photon emission in supernova remnants SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; cosmic rays; gamma rays : theory; ISM : individual (SN 1006); radiation mechanisms : nonthermal supernova remnants ID EARTHS BOW SHOCK; HYDROMAGNETIC WAVE EXCITATION; COSMIC-RAY ORIGIN; PARTICLE-ACCELERATION; GAMMA-RAYS; ELECTRON INJECTION; ION-ACCELERATION; SN-1006; SIMULATIONS; EVOLUTION AB We have extended a simple model of nonlinear diffusive shock acceleration to include the injection and acceleration of electrons and the production of photons from bremsstrahlung, synchrotron, inverse-Compton, and pion-decay processes. We argue that the results of this model, which is simpler to use than more elaborate ones, offer a significant improvement over test-particle, power-law spectra which are often used in astrophysical applications of diffusive shock acceleration. With an evolutionary supernova remnant (SNR) model to obtain shock parameters as functions of ambient interstellar medium parameters and time, we predict broadband continuum photon emission from supernova remnants in general, and SN 1006 in particular, showing that our results compare well with the more complete time-dependent and spherically symmetric nonlinear model of Berezhko, Ksenofontov, & Petukhov. We discuss the implications nonlinear shock acceleration has for X-ray line emission and use our model to describe how ambient conditions determine the TeV/radio flux ratio, an important parameter for gamma-ray observations of radio SNRs. C1 N Carolina State Univ, Dept Phys, Raleigh, NC 27695 USA. Inst Cosmophys Res & Aeron, Yakutsk 677891, Russia. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Ellison, DC (reprint author), N Carolina State Univ, Dept Phys, Box 8202, Raleigh, NC 27695 USA. NR 71 TC 124 Z9 124 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2000 VL 540 IS 1 BP 292 EP 307 DI 10.1086/309324 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356CW UT WOS:000089427600028 ER PT J AU Robinson, RD Smith, MA AF Robinson, RD Smith, MA TI A search for rotational modulation of X-ray centers on the classical Be star gamma Cassiopeiae SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : activity; stars : emission-line, Be; stars : flare; stars : individual (gamma Cassiopeiae); X-rays : stars ID WIND-ACCRETION; BINARY STARS; FLARE STARS; SS-CYGNI; VARIABILITY; EMISSION; CORONAE; SPECTRUM; SYSTEMS; PERSEI AB In this paper we discuss X-ray observations of gamma Cas obtained in 1998 November with the Rossi X-Ray Timing Explorer (RXTE). The data were obtained nearly continuously over 54 hr, which is about twice the expected rotational period. An earlier RXTE light curve obtained in 1996 March over a 27 hr period showed X-ray flux arising from short-duration shots (flares) superimposed on an undulating "basal" component that was anticorrelated with fluctuations of the UV continuum over a timescale of similar to 10 hr. The object of the present study was to (1) examine the long-term variations of the X-ray characteristics through comparisons with this earlier data and (2) to determine whether variations of the basal flux repeat during a second rotation period. A comparison of the results with the 1996 data set shows a number of similarities and differences in the X-ray behavior: (a) the mean X-ray level in 1998 was only 60% of the 1996 level, (b) the basal fluxes in 1998 vary over shorter timescales (less than 2 hr) than in 1996, (c) the shots were found to show a slightly softer (cooler) mean color than the basal component in 1998, although they were slightly hotter in 1996, (d) fluctuations in the colors of the shot and basal fluxes generally track one another in both data sets, (e) cyclical patterns of X-ray flux decrease with a period of about 7.5 hr occurred in both data sets, and (f) the frequency of shots with a given integrated energy was found to decrease exponentially with energy, although the rate of decrease in 1996 was slower than in 1998. There was only marginal evidence for a repetition during the second half of the time sequence of long-term basal flux variations seen during the first half of the observations. We suspect, however, that the large intrinsic variability of the X-ray source would have masked a true replication. We also present archival IUE data that shows the presence of UV continuum variations in 1982 with similar characteristics to those seen in 1996. This suggests that the regions responsible for the UV variability are very long lived. The data also provide the basis for a refined but still tentative rotational period of 1.12277 days. Assuming a flare paradigm and a very simple electron beam model, we examine the atmospheric heating expected for the shot events. We conclude that it is possible to explain how the measured shot temperature can be smaller than the temperature deduced for the basal X-ray emission. We also discover that if the beam model is correct then the electrons within the beam have relatively high energies (>200 keV) and are nearly monoenergetic. In three appendices we discuss arguments, first, against the idea that the X-ray emission from gamma Cas arises from mass accretion onto a hypothetical white dwarf companion or from an active late-type star and, second, in favor of its origin from near the surface of gamma Gas. C1 Catholic Univ Amer, NASA, Goddard Space Flight Ctr, Inst Astrophys & Computat Sci, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Comp Sci Corp, Baltimore, MD 21218 USA. RP Robinson, RD (reprint author), Catholic Univ Amer, NASA, Goddard Space Flight Ctr, Inst Astrophys & Computat Sci, Code 681, Greenbelt, MD 20771 USA. NR 62 TC 30 Z9 30 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2000 VL 540 IS 1 BP 474 EP 488 DI 10.1086/309310 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356CW UT WOS:000089427600045 ER PT J AU Devine, D Bally, J Reipurth, B Stocke, J Morse, J AF Devine, D Bally, J Reipurth, B Stocke, J Morse, J TI Hubble Space Telescope Planetary Camera imaging of HH 29 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : jets and outflows; stars : formation; stars : mass loss ID HARO OBJECT HH-29; SHOCK-WAVES; CLOUDS AB We present Hubble Space Telescope Hex and [S II] images of HH 29. The proximity of HH 29 (140 pc) and the high resolution of the Planetary Camera has resulted in the most detailed images obtained so far of any Herbig-Haro object. The most prominent feature is a linear Hat ridge leading the working surface of a bow shock with a chaotic trailing [S II] bright region. The high-excitation ridge is perpendicular to a line extending toward the class 0 protostar L1551-NE, supporting its recent identification as the driving source. Previous studies have identified several low-velocity features within the working surface. Our images reveal them to be miniature bow shocks facing upstream. Evidently a cluster of dense quasi-stationary clumps have been overrun by a faster, lower density flow. The shock front impacted the front of the largest clump several decades ago, and during the 1990s, a prominent gap appeared in the advancing bow shock in the wake of the obstacle. The Hubble Space Telescope images show that by 1998 the shock front had wrapped around the back of the clump, closing the shock shadow it produced. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. RP Devine, D (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. NR 16 TC 7 Z9 7 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2000 VL 540 IS 1 BP L57 EP L59 DI 10.1086/312863 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356CX UT WOS:000089427700015 ER PT J AU Nayakshin, S AF Nayakshin, S TI Magnetic flare origin of X-rays in active galactic nuclei: Photoionization evidence SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; line : formation; radiative transfer; X-rays : general ID ACCRETION DISKS; REFLECTION SPECTRA; COLD MATTER; BINARIES; CORONAE; DISCS; LINES; OUTFLOWS; MODEL AB We present full-disk X-ray reflection spectra for two currently popular accretion flow geometries for active galactic nuclei (AGNs): (1) the lamppost model, which is frequently used to discuss the iron-line reverberation in AGNs, and (2) the model in which X-rays are produced in magnetic flares above a cold accretion disk. The lamppost spectra contain several spectroscopic features that are characteristic of highly ionized material that is not seen in the X-ray spectra of most AGNs. The magnetic flare model, on the other hand, produces reflected spectra that are roughly a superposition of a power law and a neutral-like reflection and an iron K alpha line; thus, these spectra are more in line with typical AGN X-ray spectra. Furthermore, because of the difference in the ionization structure of the illuminated material in the two models, the line equivalent width increases with the X-ray luminosity L-x for the lamppost and decreases with L-x for the flare model. In light of these theoretical insights, the recent iron-line reverberation studies of AGNs, the X-ray Baldwin effect, and the general lack of X-ray reflection features in distant quasars all suggest that, for high accretion rates, the cold accretion disk is covered by a thick, completely ionized Thomson skin. Because the latter is only possible when the X-rays are concentrated in small emitting regions, we believe that this presents strong evidence for the magnetic flare origin of X-rays in AGNs. C1 NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. RP Nayakshin, S (reprint author), NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Code 661, Greenbelt, MD 20771 USA. NR 45 TC 30 Z9 30 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD SEP 1 PY 2000 VL 540 IS 1 BP L37 EP L40 DI 10.1086/312868 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356CX UT WOS:000089427700010 ER PT J AU Hasan, H Hanisch, R Bredekamp, J AF Hasan, H Hanisch, R Bredekamp, J TI NASA's astrophysics data archives SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 8th UN/ESA Workshop on Basic Space Science: Scientific Exploration from Space CY MAR 13-17, 1999 CL AL AL BAYT UNIV, MAFRAQ, JORDAN SP UN, ESA HO AL AL BAYT UNIV AB The NASA Office of Space Science has established a series of archival centers where science data acquired through its space science missions is deposited. The availability of high quality data to the general public through these open archives enables the maximization of science return of the flight missions. The Astrophysics Data Centers Coordinating Council, an informal collaboration of archival centers, coordinates data from five archival centers distiguished primarily by the wavelength range of the data deposited there. Data are available in FITS format. An overview of NASA's data centers and services is presented in this paper. A standard front-end modifyer called 'Astrowbrowse' is described. Other catalog browsers and tools include WISARD and AMASE supported by the National Space Scince Data Center, as well as ISAIA, a follow on to Astrobrowse. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. NASA Headquarters, Off Space Sci, Washington, DC 20546 USA. RP Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. NR 1 TC 0 Z9 0 U1 0 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0004-640X EI 1572-946X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 2000 VL 273 IS 1-4 BP 131 EP 139 DI 10.1023/A:1002620613422 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 366CN UT WOS:000089987400017 ER PT J AU Deutsch, MJ Bicay, MD AF Deutsch, MJ Bicay, MD TI Observing with SIRTF: Opportunities for the scientific community SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 8th UN/ESA Workshop on Basic Space Science: Scientific Exploration from Space CY MAR 13-17, 1999 CL AL AL BAYT UNIV, MAFRAQ, JORDAN SP UN, ESA HO AL AL BAYT UNIV AB The Space InfraRed Telescope Facility (SIRTF) is the fourth and final element in NASA's family of orbiting 'Great Observatories'. SIRTF consists of a 0.85-meter diameter telescope and three cryogenically-cooled science instruments capable of observing from the near- to the far-infrared, between 3 and 180 mum. Incorporating the latest in large-format infrared detector arrays, SIRTF offers orders-of-magnitude improvements in capability over existing facilities. Launch is scheduled for December 2001, with an anticipated lifetime of up to 5 years. SIRTF will observe targets ranging from small, icy bodies in the outer Solar System to the most luminous known objects in the distant reaches of the Universe. SIRTF represents an important scientific and technical bridge to NASA's new Origins program, and is managed for NASA by the Jet Propulsion Laboratory, California Institute of Technology. C1 CALTECH, Jet Prop Lab, SIRTF Project Off, Pasadena, CA 91109 USA. CALTECH, SIRTF Sci Ctr, Pasadena, CA 91125 USA. RP Deutsch, MJ (reprint author), CALTECH, Jet Prop Lab, SIRTF Project Off, MS 264-767,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 2 Z9 2 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 2000 VL 273 IS 1-4 BP 187 EP 199 DI 10.1023/A:1002724732077 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 366CN UT WOS:000089987400022 ER PT J AU Deutsch, MJ Nichols, JS AF Deutsch, MJ Nichols, JS TI Advanced approach to concept and design studies for space missions SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 8th UN/ESA Workshop on Basic Space Science: Scientific Exploration from Space CY MAR 13-17, 1999 CL AL AL BAYT UNIV, MAFRAQ, JORDAN SP UN, ESA HO AL AL BAYT UNIV AB Recent automated and advanced techniques developed at JPL have created a streamlined and fast-track approach to initial mission conceptualization and system architecture design, answering the need for rapid turnaround of trade studies for potential proposers, as well as mission and instrument study groups. JPL has assembled a team of multidisciplinary experts with corporate knowledge of space mission and instrument development. The advanced Concept Design Team, known as Team X, provides interactive design trades including cost as a design parameter, and advanced visualization for pre-Phase A mission feasibility studies. The proposer and Team X collaborate closely in developing scenarios, and Team X responds with a detailed integrated mission/instrument design and development plan within 1 week. Iteration of the plan is on a similar rapid turnaround basis. JPL has experience planning more than 250 missions, including pointed and survey astrophysics missions such as GALEX, SIM, IRAS, SIRTF, and WIRE. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Harvard Smithsonian Astrophys Observ, Chandra Xray Ctr, Cambridge, MA 02138 USA. RP Deutsch, MJ (reprint author), CALTECH, Jet Prop Lab, MS 264-767,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 7 Z9 7 U1 0 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD SEP PY 2000 VL 273 IS 1-4 BP 201 EP 206 DI 10.1023/A:1002732916148 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 366CN UT WOS:000089987400023 ER PT J AU Lee, SMC Williams, WJ Schneider, SMF AF Lee, SMC Williams, WJ Schneider, SMF TI Core temperature measurement during supine exercise: Esophageal, rectal, and intestinal temperatures SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE submaximal exercise; microgravity; thermoregulation ID SKIN BLOOD-FLOW; TYMPANIC MEMBRANE; BODY-TEMPERATURE; HEAT-BALANCE; SENSOR; HUMANS AB Background: The purpose of this study was to characterize intestinal temperature (Tin) in comparison to esophageal (Tes) and rectal temperature (Tre) during supine exercise. Methods: Seven subjects completed a continuous supine protocol of 20 min of rest, 20 min of cycle exercise at 40% peak oxygen consumption ((V)over dotO(2)peak), 20 min of cycle exercise at 65% (V)over dotO(2)peak, and 20 min of recovery. Tes, Tre, and Tin were recorded each min. Results: Temperatures were not different after 20 min of rest, but Tes and Tin were greater than Tre at the end of the 40% (Tes: 37.38 +/- 0.11; Tin: 37.35 +/- 0.06; Tre: 37.20 +/- 0.10 degrees C) and 65% (V)over dotO(2)peak stages (Tes: 37.83 +/- 0.10; Tin: 37.75 +/- 0.05; Tre: 37.63 +/- 0.08 degrees C). After 20 min of recovery, Tes (37.24 +/- 0.011 degrees C) was less than either Tre ol Tin, which were not different from each other (Tin: 37.39 +/- 0.09; Tre: 37.44 +/- 0.09 degrees C). Time to threshold for increased temperature from rest (+0.10 degrees C) for Tes (10.0 +/- 1.1 min) was not different from Tin (14.0 +/- 1.2 min) but less than Tre (15.7 +/- 1.6 min). Time to reach peak temperature was less for Tes (36.6 +/- 1.8 min) than Tin (40.6 +/- 0.9 min) and Tre (41.4 +/- 0.5 min). Similarly, time to a decrease in temperature (-0.10 degrees C) after exercise was less for Tes (3.7 +/- 0.4 min) than Tin (7.1 +/- 1.5 min) and Tre (10.6 +/- 1.9). Conclusions: Measurement of Tin may be an alternative to Tes to measure Tcore specific time points during exercise with an understanding of the slower response of Tin compared with Tes. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Wyle Labs, Life Sci Syst & Serv Div, Houston, TX USA. RP Schneider, SMF (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SD361,2101 NASA Rd 1, Houston, TX 77058 USA. NR 28 TC 38 Z9 40 U1 0 U2 5 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 SEP PY 2000 VL 71 IS 9 BP 939 EP 945 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 349RC UT WOS:000089058500011 PM 11001349 ER PT J AU Cohen, MM AF Cohen, MM TI Perception of facial features and face-to-face communications in space SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article; Proceedings Paper CT International Workshop on Human Factors in Space CY JUL 07-09, 1999 CL TOKYO, JAPAN SP Int Space Life Sci, Strateg Planning Working Grp, Natl Space Dev Agcy Japan DE face perception; communications; spaceflight ID SPEECH; RECOGNITION; ORIENTATION; ILLUSION; FLIGHT AB This paper examines how human face-to-face communications may be compromised by exposure to the microgravity environment of space. Although efficient face-to-face communications are acknowledged to be essential for astronauts to work safely and effectively, the space environment causes facial edema, and allows speakers and listeners to confront one another in multiple orientations that can potentially interfere with many important non-linguistic communication cues. In addition, high background noises in space shuttles and stations can mask auditory messages. Currently, the effects of spaceflight on the ability to identify facial features, to read lips, to integrate visual and auditory sensory information, and to interpret spoken messages in noisy environments while the speakers are at various orientations with respect to the listeners, are virtually unknown. Ground-based experiments conducted in our laboratory with computer-displayed facial images presented at various orientations have suggested how non-linguistic cues may be degraded by changes in the retinal orientations of facial images. The results of our ground-based studies illustrating impaired recognition of facial features in non-erect images are described, their implications for effective face-to-face communications among astronauts in space are discussed, and two experiments that can quantify the effects of microgravity on face-to-face communications in space are outlined. C1 NASA, Ames Res Ctr, Gravitat Res Branch,Life Sci Div, Perceptual & Behav Adaptat Grp, Moffett Field, CA 94035 USA. RP Cohen, MM (reprint author), NASA, Ames Res Ctr, Gravitat Res Branch,Life Sci Div, Perceptual & Behav Adaptat Grp, Mail Stop 239-11, Moffett Field, CA 94035 USA. NR 51 TC 4 Z9 5 U1 0 U2 1 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 SEP PY 2000 VL 71 IS 9 SU S BP A51 EP A57 PG 7 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 350VG UT WOS:000089121400011 PM 10993310 ER PT J AU Fitts, D Architecture, B AF Fitts, D Architecture, B TI An overview of NASA ISS human engineering and habitability: Past, present, and future SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article; Proceedings Paper CT International Workshop on Human Factors in Space CY JUL 07-09, 1999 CL TOKYO, JAPAN SP Int Space Life Sci, Strateg Planning Working Grp, Natl Space Dev Agcy Japan DE human engineering; human factors; habitability; space station AB The International Space Station (ISS) is the first major NASA project to provide human engineering an equal system engineering status to other disciplines. The incorporation and verification of hundreds of human engineering requirements applied across-the-board to the ISS has provided for a notably more habitable environment to support long duration spaceflight missions than might otherwise have been the case. As the ISS begins to be inhabited and become operational, much work remains in monitoring the effectiveness of the Station's built environment in supporting the range of activities required of a long-duration vehicle. With international partner participation, NASA's ISS Operational Habitability Assessment intends to carry human engineering and habitability considerations into the next phase of the ISS Program with constant attention to opportunities for cost-effective improvements that need to be and can be made to the on-orbit facility. Too, during its operations the ISS must be effectively used as an on-orbit laboratory to promote and expand human engineering/habitability awareness and knowledge to support the international space faring community with the data needed to develop future space vehicles for long-duration missions. As future space mission duration increases, the rise in importance of habitation issues make it imperative that lessons are captured from the experience of human engineering's incorporation into the ISS Program and applied to future NASA programmatic processes. C1 NASA, Lyndon B Johnson Space Ctr, Flight Projects Div, Crew Stn Branch SF6, Houston, TX 77058 USA. RP Fitts, D (reprint author), NASA, Lyndon B Johnson Space Ctr, Flight Projects Div, Crew Stn Branch SF6, 2102 NASA Rd 1, Houston, TX 77058 USA. NR 7 TC 3 Z9 4 U1 0 U2 2 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 SEP PY 2000 VL 71 IS 9 SU S BP A112 EP A116 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 350VG UT WOS:000089121400022 PM 10993321 ER PT J AU Kuroda, I Young, LR Fitts, DJ AF Kuroda, I Young, LR Fitts, DJ TI Summary of the International Workshop on Human Factors in Space SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Editorial Material C1 Japan Inst Human Factors, Tokyo 1560056, Japan. Natl Space Biomed Res Inst, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Kuroda, I (reprint author), Japan Inst Human Factors, 1-15-5 Hachimanyama,Setagaya Ward, Tokyo 1560056, Japan. NR 0 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 SEP PY 2000 VL 71 IS 9 SU S BP A3 EP A5 PG 3 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 350VG UT WOS:000089121400002 PM 10993301 ER PT J AU Novak, JB AF Novak, JB TI Summary of current issues regarding space flight habitability SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article; Proceedings Paper CT International Workshop on Human Factors in Space CY JUL 07-09, 1999 CL TOKYO, JAPAN SP Int Space Life Sci, Strateg Planning Working Grp, Natl Space Dev Agcy Japan AB One of the implicit, yet often under-emphasized qualities of human tended spaceflight is the habitability of the spacecraft and mission. This document summarizes some of the points that characterize the current status of this topic. In addition, the summary concludes with goals for future development for this issue. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Novak, JB (reprint author), NASA, Lyndon B Johnson Space Ctr, 2400 NASA Rd 1,C44, Houston, TX 77058 USA. NR 5 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 SEP PY 2000 VL 71 IS 9 SU S BP A131 EP A132 PG 2 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 350VG UT WOS:000089121400026 PM 10993325 ER PT J AU Novak, JB AF Novak, JB TI Human engineering and habitability: The critical challenges for the international space station SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article; Proceedings Paper CT International Workshop on Human Factors in Space CY JUL 07-09, 1999 CL TOKYO, JAPAN SP Int Space Life Sci, Strateg Planning Working Grp, Natl Space Dev Agcy Japan DE habitability; human factors engineering; spaceflight; ISS; space station AB As the duration of spaceflight increases, the impact of habitability on mission success becomes significant. Habitability is based on the qualities and capabilities of an environment that enable people to work and live. Poor habitability can impact productivity, safety, well-being, and performance. The International Space Station (ISS) Operational Habitability Project has been established to address the increased role of habitability for ISS. The primary objective of the project is to establish a pool of data from which opinions and decisions for judging and improving habitability on ISS will be generated. The main activities of the project are to: 1) collect and interpret data related to habitability on ISS; 2) identify Operational Habitability Lessons Learned; and 3) provide data summaries, judgments, and recommendations for the improvement of habitability. As an example, the]SS Operational Habitability Project has provided significant inputs to a current ISS issue regarding stowage. In this situation, a lack of prioritization on habitability resulted in a less than ideal situation. Operational Habitability data from previous missions was identified and summarized to provide inputs to assist in working the issues toward a resolution that supports habitability on ISS. C1 NASA, Lockheed Martin Johnson Space Ctr, Flight Project Div,Human Engn Integrat Team, Space & Life Sci Directorate, Houston, TX 77058 USA. RP Novak, JB (reprint author), NASA, Lockheed Martin Johnson Space Ctr, Flight Project Div,Human Engn Integrat Team, Space & Life Sci Directorate, 2400 NASA Rd 1,C44, Houston, TX 77058 USA. NR 1 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 SEP PY 2000 VL 71 IS 9 SU S BP A117 EP A121 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 350VG UT WOS:000089121400023 PM 10993322 ER PT J AU Palinkas, LA Gunderson, EKE Johnson, JC Holland, AW AF Palinkas, LA Gunderson, EKE Johnson, JC Holland, AW TI Behavior and performance on long-duration spaceflights: Evidence from analogue environments SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article; Proceedings Paper CT International Workshop on Human Factors in Space CY JUL 07-09, 1999 CL TOKYO, JAPAN SP Int Space Life Sci, Strateg Planning Working Grp, Natl Space Dev Agcy Japan DE Antarctica; behavior and performance; extreme environments; manned spaceflight ID SEASONAL AFFECTIVE-DISORDER; SOCIAL SUPPORT; ANTARCTICA; STRESS; DEPRESSION; PREVALENCE AB Background: Analyses of data collected in Antarctica since 1963 were conducted to identify features of behavior and performance likely to occur during long-duration missions in space. Methods: The influence of mission duration and station latitude on POMS mood scores was examined in 450 American men and women who wintered-over in Antarctica between 1991 and 1998. The influence of crewmember social characteristics, personality traits, interpersonal needs, and station environments on measures of behavior and performance at the end of the austral winter was examined in 657 American men who wintered-over between 1963 and 1974. Both data sets were used to examine the influence of crew social structure on individual performance. Results: Seasonal variations in mood appear to be associated with the altered diurnal cycle and psychological segmentation of the mission. Concurrent measures of personality, interpersonal needs, and coping styles are better predictors of depressed mood and peer-supervisor performance evaluations than baseline measures because of the unique features of the station social and physical environments and the absence of resources typically used to cope with stress elsewhere. individuals in crews with a clique structure report significantly more depression, anxiety, anger, fatigue and confusion than individuals in crews with a core-periphery structure. Depressed mood is inversely associated with severity of station physical environment, supporting the existence of a positive or "salutogenic" effect for individuals seeking challenging experiences in extreme environments. Conclusion: Behavior and performance on long-duration spaceflights is likely to be seasonal or cyclical, situational, social, and salutogenic. C1 Univ Calif San Diego, Dept Family & Prevent Med, La Jolla, CA 92093 USA. USN, Hlth Res Ctr, San Diego, CA USA. E Carolina Univ, Inst Coastal & Marine Studies, Greenville, NC USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Palinkas, LA (reprint author), Univ Calif San Diego, Dept Family & Prevent Med, 9500 Gilman Dr, La Jolla, CA 92093 USA. NR 29 TC 40 Z9 41 U1 0 U2 3 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 SEP PY 2000 VL 71 IS 9 SU S BP A29 EP A36 PG 8 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 350VG UT WOS:000089121400007 PM 10993306 ER PT J AU Rupert, AH AF Rupert, AH TI Tactile situation awareness system: Proprioceptive prostheses for sensory deficiencies SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article; Proceedings Paper CT International Workshop on Human Factors in Space CY JUL 07-09, 1999 CL TOKYO, JAPAN SP Int Space Life Sci, Strateg Planning Working Grp, Natl Space Dev Agcy Japan DE spatial disorientation; situation awareness; orientation; prosthesis AB Pilots and astronauts do not experience spatial disorientation in normal day-to-day terrestrial activities. On the ground, the perception of position and motion is determined by central nervous system integration of concordant and redundant information ii-om multiple sensory channels (somatosensory, vestibular and visual) which collectively yield veridical perceptions. In the acceleration environments experienced by pilots and astronauts, the somatosensory and vestibular senses frequently present false but concordant information concerning the direction of gravity or down. When presented with conflicting sensory stimuli, it is normal for pilots and astronauts to experience episodes of disorientation. Visual instruments and displays developed over the past 70 yr have not solved the problem. A simple solution to maintain spatial orientation is to provide true information using the same sensory channels we use so successfully on Earth. Methods: The Tactile Situation Awareness System (TSAS) developed by NASA and the U.S. Navy uses a matrix of mechanical tactile stimulators (tactors applied on the torso and limbs to convey orientation cues (e.g., gravity vector) in an intuitive fashion to the skin. A series of in-flight experiments to validate and test a variety of tactile displays and concepts has been carried out in both helicopters and fixed wing aircraft. Results: Pilots were able to fly complex maneuvers with no instruments or outside visual references (blindfolded) with less than 20 min of training. Recovery from unusual attitudes solely by tactile cues was trivial. Lab tests have shown the TSAS improves performance under conditions of high workload. Conclusions. When orientation information is presented via intuitive tactile displays spatial orientation is easily maintained in altered sensory conditions including unusual acceleration environments. C1 USN, Aerosp Med Res Lab, Pensacola, FL 32508 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Rupert, AH (reprint author), USN, Aerosp Med Res Lab, 51 Hovey Rd, Pensacola, FL 32508 USA. NR 13 TC 32 Z9 33 U1 0 U2 4 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 SEP PY 2000 VL 71 IS 9 SU S BP A92 EP A99 PG 8 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 350VG UT WOS:000089121400018 PM 10993317 ER PT J AU Whitmore, M Adolf, JA Woolford, BJ AF Whitmore, M Adolf, JA Woolford, BJ TI Habitability research priorities for the international space station and beyond SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article; Proceedings Paper CT International Workshop on Human Factors in Space CY JUL 07-09, 1999 CL TOKYO, JAPAN SP Int Space Life Sci, Strateg Planning Working Grp, Natl Space Dev Agcy Japan DE habitability; human factors; ISS; performance; workload AB Advanced technology and the desire to explore space have resulted in increasingly longer manned space missions. Long Duration Space Flights (LDSF) have provided a considerable amount of scientific research on the ability of humans to adapt and function in microgravity environments. In addition, studies conducted in analogous environments, such as winter-over expeditions in Antarctica, have complemented the scientific understanding of human performance in LDSF. These findings indicate long duration missions may take a toll on the individual, both physiologically and psychologically, with potential impacts on performance. Significant factors in any manned LDSF are habitability, workload and performance. They are interrelated and influence one another, and therefore necessitate an integrated research approach. An integral part of this approach will be identifying and developing tools not only for assessment of habitability, workload, and performance, but also for prediction of these factors as well. In addition, these tools will be used to identify and provide countermeasures to minimize decrements and maximize mission success. The purpose of this paper is to identify research goals and methods for the International Space Station (ISS) in order to identify critical factors and level of impact on habitability, workload, and performance and to develop and validate countermeasures. Overall, this approach will provide the groundwork for creating an optimal environment in which to live and work onboard ISS as well as preparing for longer planetary missions. C1 NASA, Lyndon B Johnson Space Ctr, Flight Projects Div, ISS Program Vehicle Off, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Usabil Testing & Anal Facil, ISS Program Flight Crew Integrat, Houston, TX 77058 USA. RP Whitmore, M (reprint author), NASA, Lyndon B Johnson Space Ctr, Flight Projects Div, ISS Program Vehicle Off, 2101 NASA Rd 1,Mail Code SF5, Houston, TX 77058 USA. NR 8 TC 1 Z9 1 U1 2 U2 3 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 SEP PY 2000 VL 71 IS 9 SU S BP A122 EP A125 PG 4 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 350VG UT WOS:000089121400024 PM 10993323 ER PT J AU Wood, SJ Ramsdell, CD Mullen, TJ Oman, CM Harm, DL Paloski, WH AF Wood, SJ Ramsdell, CD Mullen, TJ Oman, CM Harm, DL Paloski, WH TI Transient cardio-respiratory responses to visually induced tilt illusions SO BRAIN RESEARCH BULLETIN LA English DT Article; Proceedings Paper CT Conference on Autonomic Control During Action CY SEP, 1999 CL OPIO, FRANCE DE visual; illusions; vestibular; autonomic; cardiovascular; orthostatic ID MOTION SICKNESS; VESTIBULAR STIMULATION; AUTONOMIC REGULATION; LINEAR ACCELERATION; HUMANS; PRESSURE; SYNCOPE; SYSTEM; MICROGRAVITY; POSTURE AB Although the orthostatic cardio-respiratory response is primarily mediated by the baroreflex, studies have shown that vestibular cues also contribute in both humans and animals. We have demonstrated a visually mediated response to illusory tilt in some human subjects. Blood pressure, heart and respiration rate, and lung volume were monitored in 16 supine human subjects during two types of Visual stimulation, and compared with responses to real passive whole body tilt from supine to head 80 degrees upright. Visual tilt stimuli consisted of either a static scene from an overhead mirror or constant velocity scene motion along different body axes generated by an ultra-wide dome projection system. Visual vertical cues were initially aligned with the longitudinal body axis. Subjective tilt and self-motion were reported verbally, Although significant changes in cardio-respiratory parameters to illusory tilts could not be demonstrated for the entire group, several subjects showed significant transient decreases in mean blood pressure resembling their initial response to passive head-up tilt. Changes in pulse pressure and a slight elevation in heart rate were noted. These transient responses are consistent with the hypothesis that visual-vestibular input contributes to the initial cardiovascular adjustment to a change in posture in humans. On average the static scene elicited perceived tilt without rotation. Dome scene pitch and yaw elicited perceived tilt and rotation, and dome roll motion elicited perceived rotation without tilt. A significant correlation between the magnitude of physiological and subjective reports could not be demonstrated. (C) 2000 Elsevier Science Inc. C1 NASA, Lyndon B Johnson Space Ctr, Natl Space Biomed Res Inst, Houston, TX 77058 USA. Baylor Coll Med, Bobby R Alford Dept Otorhinolaryngol & Commun Sci, Houston, TX USA. Harvard Univ, Sch Med, Dept Anesthesia & Crit Care Clin, Boston, MA USA. Massachusetts Gen Hosp, Boston, MA USA. Harvard Univ, Sch Med, Dept Med, Boston, MA USA. Brigham & Womens Hosp, Boston, MA 02115 USA. MIT, Man Vehicle Lab, Cambridge, MA USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. RP Wood, SJ (reprint author), NASA, Lyndon B Johnson Space Ctr, Natl Space Biomed Res Inst, Mail Code SD3, Houston, TX 77058 USA. NR 39 TC 13 Z9 13 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0361-9230 J9 BRAIN RES BULL JI Brain Res. Bull. PD SEP 1 PY 2000 VL 53 IS 1 BP 25 EP 31 DI 10.1016/S0361-9230(00)00305-1 PG 7 WC Neurosciences SC Neurosciences & Neurology GA 363XC UT WOS:000089862100005 PM 11033205 ER PT J AU Serrador, JM Shoemaker, JK Brown, TE Kassam, MS Bondar, RL Schlegel, TT AF Serrador, JM Shoemaker, JK Brown, TE Kassam, MS Bondar, RL Schlegel, TT TI Cerebral vasoconstriction precedes orthostatic intolerance after parabolic flight SO BRAIN RESEARCH BULLETIN LA English DT Article; Proceedings Paper CT Conference on Autonomic Control During Action CY SEP, 1999 CL OPIO, FRANCE DE transcranial Doppler; middle cerebral artery; microgravity; head-up tilt ID BLOOD-FLOW AUTOREGULATION; HEAD-DOWN-TILT; TRANSCRANIAL DOPPLER; BED REST; SPACEFLIGHT; RESPONSES; HUMANS; STRESS; STIMULATION; PRESYNCOPE AB The effects of brief but repeated bouts of micro-and hypergravity on cerebrovascular responses to head-up tilt (HUT) were examined in 13 individuals after (compared to before) parabolic flight, Middle cerebral artery mean flow velocity (MCA MFV; transcranial Doppler ultrasound), eye level blood pressure (BP) and end tidal CO(2) (P(ET)CO(2)) were measured while supine and during 80 degrees HUT for 30 min or until presyncope. In the postflight tests subjects were classified as being orthostatically tolerant (OT) (n = 7) or intolerant (OI) (n = 6), BP was diminished with HUT in the CT group in both tests (p < 0.05) whereas postflight BP was not different from supine in the OI group. Postflight compared to preflight, the reduction in P(ET)CO(2) with HUT (p < 0.05) increased in both groups, although significantly so only in the OI group (p < 0.05), The OI group also had a significant decrease in supine MCA MRI postflight (p < 0.05) that was unaccompanied by a change in supine P(ET)CO(2). The decrease in MCA MFV that occurred during HUT in both groups preflight Go < 0.05) was accentuated only in the OI group postflight, particularly during the final 30 s of HUT (p < 0.05), However, this accentuated decrease in MCA MFV was not correlated to the greater decrease in P(ET)CO(2) during the same period (R = 0.20, p = 0.42), Although cerebral vascular resistance (CVR) also increased in the OI group during the last 30 s of HUT postflight (p < 0.05), the dynamic autoregulatory gain was not simultaneously changed. Therefore, we conclude that in the OI individuals, parabolic flight was associated with cerebral hypoperfusion following a paradoxical augmentation of CVR by a mechanism that was not related to changes in autoregulation nor strictly to changes in P(ET)CO(2). (C) 2000 Elsevier Science Inc. C1 Univ Western Ontario, Neurovasc Res Lab, Sch Kinesiol, London, ON N6A 3K7, Canada. Wyle Labs, Houston, TX USA. Ryerson Polytech Univ, Fac Engn & Appl Sci, Toronto, ON, Canada. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. RP Shoemaker, JK (reprint author), Univ Western Ontario, Neurovasc Res Lab, Sch Kinesiol, Room 3110,Thames Hall, London, ON N6A 3K7, Canada. EM kshoemak@julian.uwo.ca RI Serrador, Jorge/A-9172-2009; Shoemaker, J/L-2682-2013 NR 36 TC 14 Z9 14 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0361-9230 J9 BRAIN RES BULL JI Brain Res. Bull. PD SEP 1 PY 2000 VL 53 IS 1 BP 113 EP 120 DI 10.1016/S0361-9230(00)00315-4 PG 8 WC Neurosciences SC Neurosciences & Neurology GA 363XC UT WOS:000089862100015 PM 11033215 ER PT J AU Brown, D AF Brown, D TI A recursive Kohn variational algorithm for the Green's operator: application to the T-matrix SO CHEMICAL PHYSICS LA English DT Article ID QUANTUM SCATTERING CALCULATIONS; CROSS-SECTIONS; APPROXIMATION; MOLECULES; COLLISION; SHELL; FIELD AB A recursive version of the Kohn variational principle for the Green's operator is presented. An expression for the off-shell T-matrix is derived which is valid in the presence of a hard wall potential and which is conveniently evaluated using the recursive algorithm. The off-shell T-matrix elements for scattering systems with and without hard wall components to the potential are computed using this algorithm. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Columbia Univ, Dept Appl Phys, New York, NY 10025 USA. Goddard Inst Space Studies, New York, NY 10025 USA. RP Brown, D (reprint author), 221 Degraw St 2, Brooklyn, NY 11231 USA. NR 44 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD SEP 1 PY 2000 VL 259 IS 1 BP 11 EP 26 DI 10.1016/S0301-0104(00)00151-8 PG 16 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 348AN UT WOS:000088961700002 ER PT J AU Ortiz, RM Patterson, RM Wade, CE Byers, FM AF Ortiz, RM Patterson, RM Wade, CE Byers, FM TI Effects of acute fresh water exposure on water flux rates and osmotic responses in Kemp's ridley sea turtles (Lepidochelys kempi) SO COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR AND INTEGRATIVE PHYSIOLOGY LA English DT Article DE adrenal; aldosterone; corticosterone; deuterium; electrolytes; osmoregulation; water balance ID MANATEES TRICHECHUS-MANATUS; CARETTA-CARETTA; CHELONIA-MYDAS; STRESS; ALDOSTERONE; BLOOD; WILD AB Water flux rates and osmotic responses of Kemp's Ridley sea turtles (Lepidochelys kempi) acutely exposed to fresh water were quantified. Salt-water adapted turtles were exposed to fresh water for 4 d before being returned to salt water. During the initial salt water phase, absolute and relative water flux rates were 1.2 +/- 0.1 l d(-1) and 123.0 +/- 6.8 mi kg(-1) d(-1), respectively. When turtles were exposed to fresh water, rates increased by approximately 30%. Upon return to salt water, rates decreased to original levels. Plasma osmolality, Na+, K+, and Cl- decreased during exposure to fresh water, and subsequently increased during the return to salt water. The Na+:K+ ratio was elevated during the fresh water phase and subsequently decreased upon return to salt water. Aldosterone and corticosterone were not altered during exposure to fresh water. Elevated water flux rates during fresh water exposure reflected an increase in water consumption, resulting in a decrease in ionic and osmotic concentrations. The lack of a change in adrenocorticoids to acute fresh water exposure suggests that adrenal responsiveness to an hypo-osmotic environment may be delayed in marine turtles when compared to marine mammals. (C) 2000 Elsevier Science Inc. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Texas A&M Univ, Dept Biol, College Stn, TX 77843 USA. Texas A&M Univ, Dept Anim Sci, College Stn, TX 77843 USA. RP Ortiz, RM (reprint author), Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. NR 23 TC 7 Z9 7 U1 0 U2 8 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 1095-6433 J9 COMP BIOCHEM PHYS A JI Comp. Biochem. Physiol. A-Mol. Integr. Physiol. PD SEP PY 2000 VL 127 IS 1 BP 81 EP 87 DI 10.1016/S1095-6433(00)00240-3 PG 7 WC Biochemistry & Molecular Biology; Physiology; Zoology SC Biochemistry & Molecular Biology; Physiology; Zoology GA 356QW UT WOS:000089455000008 PM 10996820 ER PT J AU Lu, GY Behling, MB Halford, GR AF Lu, GY Behling, MB Halford, GR TI Bithermal low-cycle fatigue evaluation of automotive exhaust system alloy SS409 SO FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES LA English DT Article DE SS409; thermomechanical fatigue; low-cycle fatigue; bithermal fatigue; strain range partitioning; exhaust system AB This investigation provides thermomechanical fatigue data for the ferritic stainless steel alloy SS409, used extensively in automotive exhaust system components. The data were generated to assess the total strain version of the strain range partitioning (TS-SRP) method for the design and durability assessment of automotive exhaust systems. The cyclic lifetime and the cyclic stress-strain-temperature-time behaviour for alloy SS409 were measured using bithermal tests with extreme temperatures of 400 and 800 degrees C. Fatigue lives ranged up to 10 000 cycles with hold-times of 0.33-2.0 min. The bithermal fatigue behaviour was compared to isothermal, strain-controlled fatigue behaviour at both 400 and 800 degrees C. Thermomechanical cycling was found to have a profound detrimental influence on the fatigue resistance of SS409 compared to isothermal cycling. Supplementary bithermal tests with hold-times ranging from 40 s to 1.5 h were conducted to calibrate the TS-SRP equation for extrapolation to longer lifetimes. The observed thermomechanical (bithermal) fatigue lives correlated well with estimated lives using the TS-SRP equations: 70% of the bithermal fatigue data fall within a factor of 1.2 of calculated life; 85% within a factor of 1.4; and 100% within a factor of 1.8. C1 Arvin Exhaust Syst, Columbus, IN 47201 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Lu, GY (reprint author), GM Corp, Ctr Tech, VSAS Global Proc Ctr, Mail Code 480-305-200,6440E,12 Mile Rd, Warren, MI 48090 USA. NR 11 TC 1 Z9 1 U1 2 U2 3 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 8756-758X J9 FATIGUE FRACT ENG M JI Fatigue Fract. Eng. Mater. Struct. PD SEP PY 2000 VL 23 IS 9 BP 787 EP 794 DI 10.1046/j.1460-2695.2000.00310.x PG 8 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 364HL UT WOS:000089886900006 ER PT J AU Knight, NF Jaunky, N Lawson, RE Ambur, DR AF Knight, NF Jaunky, N Lawson, RE Ambur, DR TI Penetration simulation for uncontained engine debris impact on fuselage-like panels using LS-DYNA SO FINITE ELEMENTS IN ANALYSIS AND DESIGN LA English DT Article DE impact; penetration; LS-DYNA; finite elements AB Modeling and simulation requirements for uncontained engine debris impact on fuselage skins are proposed and assessed using the tied-nodes-with-failure modeling approach for penetration. A finite element analysis is used to study the penetration of aluminum plates impacted by titanium impactors in order to simulate the effect of such uncontained engine debris impacts on aircraft fuselage-like skin panels. LS-DYNA is used in the simulations to model the impactor, test fixture frame and target barrier plate. The effects of mesh refinement, contact modeling, and impactor initial velocity and orientation are studied using a configuration for which limited test data are available for comparison. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Veridian MRJ Engn, Yorktown, VA 23693 USA. Eagle Aeronaut Inc, Newport News, VA 23606 USA. Newport News Ship Bldg & Dry Dock Co, Newport News, VA 23607 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Knight, NF (reprint author), Veridian MRJ Engn, Yorktown, VA 23693 USA. NR 33 TC 26 Z9 30 U1 3 U2 9 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-874X J9 FINITE ELEM ANAL DES JI Finite Elem. Anal. Des. PD SEP 1 PY 2000 VL 36 IS 2 BP 99 EP 133 PG 35 WC Mathematics, Applied; Mechanics SC Mathematics; Mechanics GA 335KT UT WOS:000088243200001 ER PT J AU Manney, GL Sabutis, JL AF Manney, GL Sabutis, JL TI Development of the polar vortex in the 1999-2000 Arctic winter stratosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OZONE LOSS; METEOROLOGY AB The 1999-2000 Arctic stratospheric vortex was unusually cold, especially in the early winter lower stratosphere, with a larger area near polar stratospheric cloud formation temperatures in Dec and Jan, and much lower temperatures averaged over Nov-Jan, than any previously observed Arctic winter. In Nov and early Dec, there was a double jet in the upper stratosphere, with the anticyclone cutoff in a region of cyclonic material. By late Dec, there was a discontinuous vortex, large in the upper stratosphere, small in the lower stratosphere; evolving to a strong, continuous, relatively upright vortex by mid-Jan. This vortex evolution in 1999-2000 is typical of that in other cold early winters. Despite unusually low temperatures, the lower stratospheric vortex developed more slowly than in previous unusually cold early winters, and was weaker than average until late Dec. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. New Mexico Highlands Univ, Dept Phys, Las Vegas, NM 87701 USA. RP Manney, GL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 75 Z9 75 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 SEP 1 PY 2000 VL 27 IS 17 BP 2589 EP 2592 DI 10.1029/2000GL011703 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700001 ER PT J AU McPeters, RD Janz, SJ Hilsenrath, E Brown, TL Flittner, DE Heath, DF AF McPeters, RD Janz, SJ Hilsenrath, E Brown, TL Flittner, DE Heath, DF TI The retrieval of O-3 profiles from limb scatter measurements: Results from the Shuttle Ozone Limb Sounding Experiment SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RADIANCE CALIBRATIONS; INSTRUMENTS AB Two instruments were flown on Shuttle flight STS-87 to test a new technique for inferring the ozone vertical profile using measurements of scattered sunlight from the Earth's limb. The instruments were an ultraviolet imaging spectrometer designed to measure ozone between 30 and 50 km, and a multi-filter imaging photometer that uses 600 nm radiances to measure ozone between 15 km and 35 km. Two orbits of limb data were obtained on December 2, 1997. For the scans analyzed, the ozone profile was measured from 15 km to 45 km with approximately 3 km vertical resolution. Comparisons with a profile from an ozonesonde launched from Ascension Island showed agreement mostly within +/-5%. The tropopause at 15 km appears to have been detected in this comparison. A comparison with two HALOE ozone profiles showed that on average ozone measured by SOLSE was lower by 9% +/-5% in the 30 km to 45 km range. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Arizona, Inst Atmospher Phys, Tucson, AZ 85721 USA. RSI, Boulder, CO 80303 USA. RP McPeters, RD (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Code 916, Greenbelt, MD 20771 USA. RI McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 12 TC 73 Z9 77 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 SEP 1 PY 2000 VL 27 IS 17 BP 2597 EP 2600 DI 10.1029/1999GL011342 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700003 ER PT J AU Fahey, DW Gao, RS Del Negro, LA Keim, ER Kawa, SR Salawitch, RJ Wennberg, PO Hanisco, TF Lanzendorf, EJ Perkins, KK Lloyd, SA Swartz, WH Proffitt, MH Margitan, JJ Wilson, JC Stimpfle, RM Cohen, RC McElroy, CT Webster, CR Loewenstein, M Elkins, JW Bui, TP AF Fahey, DW Gao, RS Del Negro, LA Keim, ER Kawa, SR Salawitch, RJ Wennberg, PO Hanisco, TF Lanzendorf, EJ Perkins, KK Lloyd, SA Swartz, WH Proffitt, MH Margitan, JJ Wilson, JC Stimpfle, RM Cohen, RC McElroy, CT Webster, CR Loewenstein, M Elkins, JW Bui, TP TI Ozone destruction and production rates between spring and autumn in the Arctic stratosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SUMMER; PHOTOCHEMISTRY; NITROGEN; POLARIS; NO2; O-3; RADICALS; REGION; CLO AB In situ measurements of radical and long-lived species were made in the lower Arctic stratosphere (18 to 20 km) between spring and early autumn in 1997. The measurements include O-3, ClO, OH, HO2, NO, NO2, N2O, CO, and overhead O-3 A photochemical box model constrained by these and other observations is used to compute the diurnally averaged destruction and production rates of O-3 in this region. The rates show a strong dependence on solar exposure and ambient O-3. Total destruction rates, which reach 19%/month in summer, reveal the predominant role of NOx and HOx catalytic cycles throughout the period. Production of O-3 is significant only in midsummer air parcels. A comparison of observed O-3 changes with destruction rates and transport effects indicates the predominant role of destruction in spring and an increased role of transport by early autumn. C1 NOAA, Aeron Lab, Boulder, CO 80303 USA. Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80303 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Aerospace Corp, Los Angeles, CA 90009 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. Harvard Univ, Dept Chem, Cambridge, MA 02138 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Univ Maryland, Dept Chem & Biochem, College Pk, MD 20723 USA. Univ Denver, Dept Engn, Denver, CO 80208 USA. Atmospher Environm Serv, Downsview, ON, Canada. Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Fahey, DW (reprint author), NOAA, Aeron Lab, 325 Broadway, Boulder, CO 80303 USA. RI Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Wennberg, Paul/A-5460-2012; Swartz, William/A-1965-2010; Kawa, Stephan/E-9040-2012; Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; Swartz, William/0000-0002-9172-7189; Fahey, David/0000-0003-1720-0634 NR 21 TC 15 Z9 15 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 SEP 1 PY 2000 VL 27 IS 17 BP 2605 EP 2608 DI 10.1029/2000GL011404 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700005 ER PT J AU Notholt, J Toon, GC Sen, B Jones, NB Rinsland, CP Lehmann, R Rex, M AF Notholt, J Toon, GC Sen, B Jones, NB Rinsland, CP Lehmann, R Rex, M TI Variations in the tropical uplift following the Pinatubo eruption studied by infrared solar absorption spectrometry SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HALOGEN OCCULTATION EXPERIMENT; QUASI-BIENNIAL OSCILLATION; MT-PINATUBO; AEROSOLS; STRATOSPHERE; CIRCULATION; OZONE AB Infrared solar absorption spectra of atmospheric trace gases were measured during a ship cruise in October 1996 between 57 degrees N and 45 degrees S. The abundances of stratospheric species are compared with those derived from NASA DC-8 aircraft spectra from spring 1992, recorded seven months after the Pinatubo eruption. We examine column abundances of HCl, HF and HNO3 to study variations in the tropical uplift, following the enhanced aerosol loading. The comparison yields a vertical shift in the mixing ratio profiles of HCl and HF of less than 1 km at 25 km altitude (Post Pinatubo Versus 1996), which is of the same order of magnitude as the known seasonal, longitudinal and year-to-year variabilities of the tropical uplift. The results suggest that long term pertubations following the eruption, like the observed long term ozone reduction at midlatitudes, are mainly chemical in nature rather than the result of sustained dynamical pertubations. C1 Alfred Wegener Inst Polar & Marine Res, D-14473 Potsdam, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Inst Water & Atmospher Res, Lauder, New Zealand. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Notholt, J (reprint author), Alfred Wegener Inst Polar & Marine Res, Telegraphenberg A43, D-14473 Potsdam, Germany. RI Rex, Markus/A-6054-2009; Jones, Nicholas/G-5575-2011; Notholt, Justus/P-4520-2016 OI Rex, Markus/0000-0001-7847-8221; Jones, Nicholas/0000-0002-0111-2368; Notholt, Justus/0000-0002-3324-885X NR 24 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 SEP 1 PY 2000 VL 27 IS 17 BP 2609 EP 2612 DI 10.1029/1999GL011330 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700006 ER PT J AU Sandor, BJ Jensen, EJ Stone, EM Read, WG Waters, JW Mergenthaler, JL AF Sandor, BJ Jensen, EJ Stone, EM Read, WG Waters, JW Mergenthaler, JL TI Upper tropospheric humidity and thin cirrus SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LIMB SOUNDER; WATER-VAPOR; UARS MLS AB Upper tropospheric water vapor data from the UARS Microwave Limb Sounder (MLS) are compared with coincident optically thin (often subvisible) cirrus cloud measurements from the UARS Cryogenic Limb Array Etalon Spectrometer (CLAES) at 147 hPa in the tropics. A strong correlation is found between mean relative humidity with respect to ice (RHI) and percent occurrence of cirrus clouds. The cloudiness - RHI relationship is established from the coincident CLAES and MLS observations (Oct. 1991-May 1993), and used with 1991-97 MLS data to find by proxy the percent occurrence of cirrus for 1993-97. Interannual variability of cloudiness is investigated with the extended (1991-97) cirrus data, and a clear El Nine signature is seen. The observed relationship of RHI and optically thin cirrus provides a potential diagnostic of climatological behavior of atmospheric models, in which cirrus is important for radiative balance, heterogeneous chemistry, and the near-tropopause water budget. C1 Natl Ctr Atmospher Res, Boulder, CO 80307 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Lockheed Palo Alto Res Labs, Palo Alto, CA 94304 USA. RP Sandor, BJ (reprint author), Space Sci Inst, 3100 Marine St,Suite A353, Boulder, CO 80303 USA. NR 17 TC 20 Z9 20 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 SEP 1 PY 2000 VL 27 IS 17 BP 2645 EP 2648 DI 10.1029/1999GL011194 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700015 ER PT J AU Kleidman, RG Kaufman, YJ Gao, BC Remer, LA Brackett, VG Ferrare, RA Browell, EV Ismail, S AF Kleidman, RG Kaufman, YJ Gao, BC Remer, LA Brackett, VG Ferrare, RA Browell, EV Ismail, S TI Remote sensing of total precipitable water vapor in the near-IR over ocean glint SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INSTRUMENT; AEROSOL AB A method for remote sensing of total precipitable water vapor using water vapor absorption band at 0.94 mu m was previously developed for continental regions. Here we apply a similar technique for ocean areas over the glint region. The glint, or oceanic specular reflection, has a high value of surface reflectance and thus, can work as well as or better than applications over land regions. The method is applied for glint regions measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) simulator, an imager flown on the NASA. ER-2 research aircraft and simulating the expected measurements from the MODIS instrument on board the Earth Observing System (EOS)-Terra satellite. The measurements are made for the Atlantic coast of the United States during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). The remote sensing technique is compared with measurements of water vapor column by the Lidar Atmospheric Sensing Experiment (LASE) Differential Infrared Absorption Lidar (DIAL) lidar system also on board the ER-2. Water vapor was derived with an error of +/-5 mm PW (precipitable water vapor). Most of the errors are associated with the limitations of an experiment that was not originally designed for this purpose. Much better performance is expected from the actual MODIS instrument. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. USN, Res Lab, Washington, DC 20375 USA. NASA, Langley Res Ctr, SAIC, Hampton, VA 23665 USA. RP Kleidman, RG (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. NR 9 TC 18 Z9 19 U1 1 U2 5 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 SEP 1 PY 2000 VL 27 IS 17 BP 2657 EP 2660 DI 10.1029/1999GL011156 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700018 ER PT J AU Kim, YJ AF Kim, YJ TI A physical-model-based, field-wise and self-contained algorithm for removing directional ambiguities of ocean surface winds retrieved from scatterometer measurements SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PRESSURE FIELDS AB An algorithm is introduced to remove the directional ambiguities in ocean surface winds measured by scatterometers, which requires scatterometer data only. It is based on two Versions of PBL (planetary boundary layer) models and a lowpass filter. A pressure field is first derived from the median-filtered scatterometer winds, is then noise-filtered, and is finally converted back to the winds, respectively, by an inverted PBL model, a smoothing algorithm, and a PBL model. The derived wind field is used to remove the directional ambiguities in the scatterometer data. This new algorithm is applied to Hurricane Eugene and produces results comparable to those from the current standard ambiguity removal algorithm for NASA/JPL SeaWinds project, which requires external numerical weather forecast/analyses data. C1 CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Kim, YJ (reprint author), USN, Res Lab, Marine Meteorol Div, Global Modeling Sect, 7 Grace Hopper Ave,Stop 2, Monterey, CA 93943 USA. 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 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD SEP 1 PY 2000 VL 27 IS 17 BP 2665 EP 2668 DI 10.1029/2000GL011519 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700020 ER PT J AU Delaygue, G Jouzel, J Masson, V Koster, RD Bard, E AF Delaygue, G Jouzel, J Masson, V Koster, RD Bard, E TI Validity of the isotopic thermometer in central Antarctica: limited impact of glacial precipitation seasonality and moisture origin. SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ICE CORE; GCM ANALYSIS; CLIMATE; TEMPERATURE; GREENLAND; PALEOTHERMOMETER; PROFILES; MODELS AB The classical interpretation of water stable isotopes (deuterium or oxygen Is) retrieved from ice cores into past local temperature relies on the use of the spatial isotope/temperature slope as a surrogate of the temporal slope. Whereas this assumption has been challenged by independent methods in central Greenland, it is still considered as valid in central Antarctica. We use an atmospheric General Circulation Model (GCM) to study two parameters highlighted by previous studies as being among the most important with respect to this assumption. We show that in the GCM, between present-day and Last Glacial Maximum, the change in precipitation seasonality and the cooling of the moisture sources have limited and opposite effects on the isotopic record of the Antarctic local temperature. This conclusion strengthens the validity of the classical interpretation of isotope records in central Antarctica. C1 CEA Saclay, LSCE, F-91191 Gif Sur Yvette, France. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. CEREGE, F-13545 Aix En Provence, France. RP Delaygue, G (reprint author), CEA Saclay, LSCE, Bat 709, F-91191 Gif Sur Yvette, France. RI Koster, Randal/F-5881-2012; Masson-Delmotte, Valerie/G-1995-2011; Bard, Edouard/G-7717-2014 OI Koster, Randal/0000-0001-6418-6383; Masson-Delmotte, Valerie/0000-0001-8296-381X; NR 21 TC 29 Z9 30 U1 0 U2 4 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 SEP 1 PY 2000 VL 27 IS 17 BP 2677 EP 2680 DI 10.1029/2000GL011530 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700023 ER PT J AU Foster, J Bevis, M Schroeder, T Merrifield, M Businger, S Dorn, S Marcus, S Dickey, J Bar-Sever, Y AF Foster, J Bevis, M Schroeder, T Merrifield, M Businger, S Dorn, S Marcus, S Dickey, J Bar-Sever, Y TI El Nino, water vapor, and the Global Positioning System SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GPS METEOROLOGY; PRECIPITABLE WATER AB The 1997-1998 El Nine had a profound impact on atmospheric circulation in the tropical Pacific and affected weather patterns world-wide. Precipitable water estimates from Global Positioning System (GPS) sites in the western tropical Pacific capture the sudden onset of large-scale subsidence, a phenomenon proposed as a possible mechanism driving the eventual decline of El Nino episodes. The atmospheric drying associated with this anomalous high-pressure ridge and the turnabout as the warm episode transitions into the subsequent La Nino are clearly visible in the GPS observations. C1 Univ Hawaii, SOEST, Honolulu, HI 96822 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Foster, J (reprint author), Univ Hawaii, SOEST, Honolulu, HI 96822 USA. RI Foster, James/G-7942-2012; OI Foster, James/0000-0003-2052-5798; Marcus, Steven/0000-0002-5763-6961 NR 7 TC 6 Z9 6 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 SEP 1 PY 2000 VL 27 IS 17 BP 2697 EP 2700 DI 10.1029/2000GL011429 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700028 ER PT J AU Hurst, KJ Argus, DF Donnellan, A Heflin, MB Jefferson, DC Lyzenga, GA Parker, JW Smith, M Webb, FH Zumberge, JF AF Hurst, KJ Argus, DF Donnellan, A Heflin, MB Jefferson, DC Lyzenga, GA Parker, JW Smith, M Webb, FH Zumberge, JF TI The coseismic geodetic signature of the 1999 Hector Mine Earthquake SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The M=7.1 Hector Mine earthquake ruptured the Lavic Lake fault near Twentynine Palms, CA at 09:46 UTC October 16, 1999. Because it occurred near the eastern edge of the Southern California Integrated GPS Network (SCIGN), a network of permanent, continuously recording GPS receivers for measuring the crustal deformation field around Los Angeles, CA, it was possible to determine the deformation associated with the earthquake with unprecedented speed and reliability. Thirty-four stations recorded displacements over the 3-sigma level. The displacements measured with GPS can be modeled by a fault 46.2 +/- 2.6 km long, 8.2 +/- 1.0 km wide, striking 330 degrees, dipping 84 degrees east, with 301 +/- 36 cm right lateral strike-slip, and 145 +/- 36 cm of east-up dip-slip, yielding a potency of 1.3 km(3) and geodetic moment of 3.8 x 10(26) dyne-cm. The trace and dip of the model fault is consistent with the observed ground rupture and seismic focal mechanisms. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Harvey Mudd Coll, Claremont, CA 91711 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Hurst, KJ (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RI Argus, Donald/F-7704-2011 NR 4 TC 23 Z9 23 U1 0 U2 4 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 SEP 1 PY 2000 VL 27 IS 17 BP 2733 EP 2736 DI 10.1029/2000GL011841 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700037 ER PT J AU Purucker, ME Dyment, J AF Purucker, ME Dyment, J TI Satellite magnetic anomalies related to seafloor spreading in the South Atlantic Ocean SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID REMANENT MAGNETIZATION; MAGSAT DATA; FIELD; CORE; SPECTRUM; MODELS; VECTOR AB Oceanic magnetic anomalies have been observed from satellite. The strongest anomalies are the long-wavelength components of the sea-floor spreading signature. Unfortunately, because of technical issues involving the treatment of satellite magnetic data, these signals are obscured in the South Atlantic Ocean because they trend north-south However, a map does exist in which such features are observed, essentially because of a better data processing technique. Further, this map agrees with a physically motivated model based on non-satellite magnetic input. Hence, with properly treated data, the magnetic anomaly maps should be useful for saying something about the geology, rather than vice-versa. This situation will be considerably improved by ongoing advances in methods and new data sets. The amplitude of the observations, a factor of two larger than previous estimates, confirms that the extrusive basaltic layer alone is inadequate to produce the signal and that deeper oceanic sources are required. C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS, Geodynam Branch, Greenbelt, MD 20771 USA. Univ Bretagne Occidentale, CNRS UMR Domaines Ocean, Inst Univ Europeen Mer, Technopole Brest Iroise, F-29280 Plouzane, France. RP Purucker, ME (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS, Geodynam Branch, Code 921, Greenbelt, MD 20771 USA. RI ipgp, Laboratoire geoscien/F-8471-2010; Dyment, Jerome/A-6788-2011; IPGP, Geosciences Marines/F-8780-2010 NR 21 TC 13 Z9 14 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 SEP 1 PY 2000 VL 27 IS 17 BP 2765 EP 2768 DI 10.1029/1999GL008437 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700045 ER PT J AU Papitashvili, VO Papitashvili, NE King, JH AF Papitashvili, VO Papitashvili, NE King, JH TI Solar cycle effects in planetary geomagnetic activity: Analysis of 36-year long OMNI dataset SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB NSSDC's OMNI dataset, which now spans 1963-1999, contains a collection of hourly means of interplanetary magnetic field (IMF) and solar wind (SW) plasma parameters measured near the Earth's orbit, as well as some auxiliary data. We report a study of solar cycle effects in planetary geomagnetic activity in which 27-day averages of several OMNI parameters are compared with equivalent Kp and Dst averages. Some established trends in these parameters over solar cycles are confirmed; for example, it is concluded that changes in the magnitude (rather than in direction) constitute the primary solar cycle variation in the IMF. However, this study also reveals that long-term changes in planetary geomagnetic activity are driven more actively by solar wind-magnetosphere coupling of an electrodynamic nature rather than by plasma transport into the magnetosphere. This suggests that ambient (background) interplanetary "electric" environment (in which the Earth's magnetosphere is immersed over the solar cycles) may play a more significant role in causing changes in the frequency of geomagnetic storms and substorms than previously realized. C1 Univ Michigan, SPRL, Ann Arbor, MI 48109 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Papitashvili, VO (reprint author), Univ Michigan, SPRL, 2455 Hayward St, Ann Arbor, MI 48109 USA. OI Papitashvili, Vladimir/0000-0001-6955-4894 NR 14 TC 28 Z9 29 U1 0 U2 7 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 SEP 1 PY 2000 VL 27 IS 17 BP 2797 EP 2800 DI 10.1029/2000GL000064 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 353BW UT WOS:000089254700053 ER PT J AU Walter, BP Heimann, M AF Walter, BP Heimann, M TI A process-based, climate-sensitive model to derive methane emissions from natural wetlands: Application to five wetland sites, sensitivity to model parameters, and climate SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID AMAZON RIVER FLOODPLAIN; OLIGOTROPHIC PINE FEN; WATER-TABLE; MINNESOTA PEATLANDS; OXIDATION POTENTIALS; ATMOSPHERIC METHANE; NORTHERN MINNESOTA; BOREAL PEATLANDS; CARBON-DIOXIDE; ARCTIC TUNDRA AB Methane emissions from natural wetlands constitute the largest methane source at present and depend highly on the climate. In order to investigate the response of methane emissions from natural wetlands to climate variations, a one-dimensional process-based climate-sensitive model to derive methane emissions from natural wetlands is developed. In the model the processes leading to methane emission are simulated within a one-dimensional soil column and the three different transport mechanisms, diffusion, plant-mediated transport, and ebullition, are modeled explicitly. The model forcing consists of daily values of soil temperature, water table, and net primary productivity, and at permafrost sites the thaw depth is included. The methane model is tested using observational data obtained at five wetland sites located in North America, Europe, and Central America, representing a large variety of environmental conditions. It can be shown that in most cases seasonal variations in methane emissions can be explained by the combined effect of changes in soil temperature and the position of the water table. Our results also show that a process-based approach is needed because there is no simple relationship between these controlling factors and methane emissions that applies to a variety of wetland sites. The sensitivity of the model to the choice of key model parameters is tested and further sensitivity tests are performed to demonstrate how methane emissions from wetlands respond to longer-term climate variations. C1 Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Max Planck Inst Biogeochem, D-07701 Jena, Germany. Max Planck Inst Meteorol, Hamburg, Germany. RP Walter, BP (reprint author), Columbia Univ, NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM bwalter@giss.nasa.gov; martin.heimann@bgc-jena.mpg.de RI Heimann, Martin/H-7807-2016 OI Heimann, Martin/0000-0001-6296-5113 NR 81 TC 200 Z9 209 U1 4 U2 61 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD SEP PY 2000 VL 14 IS 3 BP 745 EP 765 DI 10.1029/1999GB001204 PG 21 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA 350EZ UT WOS:000089089000004 ER PT J AU Remington, RW Johnston, JC Ruthruff, E Gold, M Romera, M AF Remington, RW Johnston, JC Ruthruff, E Gold, M Romera, M TI Visual search in complex displays: Factors affecting conflict detection by air traffic controllers SO HUMAN FACTORS LA English DT Article AB Recent free flight proposals to relax airspace constraints and give greater autonomy to aircraft have raised concerns about their impact on controller performance. Relaxing route and altitude restrictions would reduce the regularity of traffic through individual sectors, possibly impairing controller situation awareness. We examined the impact of this reduced regularity in four visual search experiments that tested controllers' detection of traffic conflicts in the four conditions created by factorial manipulation of fixed routes (present vs, absent) and altitude restrictions (present vs, absent). These four conditions were tested under varying levels of traffic load and conflict geometry (conflict time and conflict angle). Traffic load and conflict geometry showed strong and consistent effects in all experiments. Color coding altitude also substantially improved detection times. In contrast, removing altitude restrictions had only a small negative impact, and removing route restrictions had virtually no negative impact. In some cases conflict detection was actually better without fixed routes. The-implications and limitations of these results for the feasibility of free flight are discussed. Actual or potential applications include providing guidance in the selection of free flight operational concepts. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. San Jose State Univ Fdn, San Jose, CA USA. RP Remington, RW (reprint author), NASA, Ames Res Ctr, MS 262-4, Moffett Field, CA 94035 USA. NR 26 TC 43 Z9 46 U1 2 U2 3 PU HUMAN FACTORS SOC PI SANTA MONICA PA BOX 1369, SANTA MONICA, CA 90406 USA SN 0018-7208 J9 HUM FACTORS JI Hum. Factors PD FAL PY 2000 VL 42 IS 3 BP 349 EP 366 DI 10.1518/001872000779698105 PG 18 WC Behavioral Sciences; Engineering, Industrial; Ergonomics; Psychology, Applied; Psychology SC Behavioral Sciences; Engineering; Psychology GA 382ZZ UT WOS:000165858400001 PM 11132797 ER PT J AU Sidher, SD Griffin, MJ Davis, GR Swinyard, BM Burgdorf, M Orton, GS Rudy, DJ Encrenaz, T Lellouch, E de Graauw, T AF Sidher, SD Griffin, MJ Davis, GR Swinyard, BM Burgdorf, M Orton, GS Rudy, DJ Encrenaz, T Lellouch, E de Graauw, T TI ISO LWS observations of Mars - Detection of rotational modulation in the far infrared SO ICARUS LA English DT Article DE infrared observations; Mars; surface; spectroscopy ID LONG-WAVELENGTH SPECTROMETER; BRIGHTNESS TEMPERATURE; MARINER-9; NEPTUNE; URANUS AB A series of far infrared (FIR) spectra of Mars between 43 and 196 mu m was taken with the Long Wavelength Spectrometer (LWS) on board the European Space Agency's Infrared Space Observatory (ISO). Analysis of these medium-resolution data reveals a rotational modulation of the disk-averaged FIR brightness temperature. The observed variability of +/- 1.5% in the LWS wavelength range compares favorably with the predictions of a thermophysical model of the martian surface. A surface emissivity of similar to 0.90 gives good agreement between the measured and the modeled brightness temperatures and leads to an improved estimate of the LWS photometric calibration uncertainty, (C) 2000 Academic Press. C1 Univ London Queen Mary & Westfield Coll, London E1 4NS, England. Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England. Univ Saskatchewan, Saskatoon, SK, Canada. ISO Data Ctr, Madrid 28080, Spain. CALTECH, Jet Prop Lab, Pasadena, CA USA. Aerospace Corp, El Segundo, CA 90245 USA. Observ Paris, F-92195 Meudon, France. SRON, NL-9747 AD Groningen, Netherlands. RP Sidher, SD (reprint author), Univ London Queen Mary & Westfield Coll, Mile End Rd, London E1 4NS, England. NR 22 TC 12 Z9 12 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 2000 VL 147 IS 1 BP 35 EP 41 DI 10.1006/icar.2000.6436 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349WG UT WOS:000089068100004 ER PT J AU Allen, CC Albert, FG Chafetz, HS Combie, J Graham, CR Kieft, TL Kivett, SJ McKay, DS Steele, A Taunton, AE Taylor, MR Thomas-Keprta, KL Westall, F AF Allen, CC Albert, FG Chafetz, HS Combie, J Graham, CR Kieft, TL Kivett, SJ McKay, DS Steele, A Taunton, AE Taylor, MR Thomas-Keprta, KL Westall, F TI Microscopic physical biomarkers in carbonate hot springs: Implications in the search for life on Mars SO ICARUS LA English DT Article DE Mars; Earth; exobiology; biomarker; biofilm ID TRAVERTINE SHRUBS; NEUTRAL PH; BACTERIA; NANNOBACTERIA; PRECIPITATION; SEDIMENTS; BIOFILMS AB Physical evidence of life (physical biomarkers) from the deposits of carbonate hot springs were documented at the scale of microorganisms-submillimeter to submicrometer. The four moderate-temperature (57 to 72 degrees C), neutral pH springs reported on in this study, support diverse communities of bacteria adapted to specific physical and chemical conditions. Some of the microbes coexist with travertine deposits in endolithic communities. In other cases, the microbes are rapidly coated and destroyed by precipitates but leave distinctive mineral fabrics. Some microbes adapted to carbonate hot springs produce an extracellular polymeric substance which forms a three-dimensional matrix with living cells and cell remains, known as a biofilm. Silicon and iron oxides often coat the biofilm, leading to long-term preservation. Submicrometer mineralized spheres composed of calcium fluoride or silica are common in carbonate hot spring deposits. Sphere formation is biologically mediated, but the spheres themselves are apparently not fossils or microbes. Additionally, some microbes selectively weather mineral surfaces in distinctive patterns. Hot spring deposits have been cited as prime locations for exobiological exploration of Mars. The presence of preserved microscopic physical biomarkers at all four sites supports a strategy of searching for evidence of life in hot spring deposits on Mars. (C) 2000 Academic Press. C1 Lockheed Martin Space Operat, Houston, TX 77058 USA. Montana Biotech Corp, Belgrade, MT USA. Univ Houston, Houston, TX USA. Harvard Univ, Cambridge, MA 02138 USA. New Mexico Inst Min & Technol, Socorro, NM 87801 USA. Univ Washington, Seattle, WA 98195 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Portsmouth, Portsmouth PO1 2UP, Hants, England. Univ Wisconsin, Madison, WI 53706 USA. Henderson State Univ, Arkadelphia, AK USA. Lunar & Planetary Inst, Houston, TX 77058 USA. RP Allen, CC (reprint author), Lockheed Martin Space Operat, Mail Code C23, Houston, TX 77058 USA. NR 56 TC 49 Z9 51 U1 4 U2 16 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 2000 VL 147 IS 1 BP 49 EP 67 DI 10.1006/icar.2000.6435 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349WG UT WOS:000089068100006 PM 11543582 ER PT J AU Tsapin, AI Goldfeld, MG McDonald, GD Nealson, KH Moskovitz, B Solheid, P Kemner, KM Kelly, SD Orlandini, KA AF Tsapin, AI Goldfeld, MG McDonald, GD Nealson, KH Moskovitz, B Solheid, P Kemner, KM Kelly, SD Orlandini, KA TI Iron(VI): Hypothetical candidate for the martian oxidant SO ICARUS LA English DT Article ID POTASSIUM FERRATE; OXIDATION; MARS; MECHANISM; KINETICS; SOIL; EXCHANGE; PEROXIDE; SURFACE; MOSSBAUER AB As a result of the Viking missions of the early 1970s, the presence of a strong oxidant in martian soil was suggested. Here we present a hypothesis, testable by near-term missions, that iron(VI) is a likely contributor to the martian oxidative pool. In this context, ferrate(VI) salts, with FeO42- anion, were studied for their spectral and oxidative properties. Ferrate(VI) has distinctive spectroscopic features that make it available for detection by remote sensing reflectance spectra and contact measurements via Mossbauer spectroscopy, and the relevant miniaturized instrumentation has been developed or is under way, while for the returned samples XANES spectroscopy is shown to be a method of choice. Ferrate(VI) is capable of splitting water to yield molecular oxygen, and oxidizing organic carbon into CO2. These activities were strongly abated after treatment at elevated temperatures, similar to observations with martian soil samples in the Viking mission. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Minnesota, Dept Geol & Geophys, Minneapolis, MN 55455 USA. Argonne Natl Lab, Div Environm Res, Argonne, IL 60439 USA. RP Tsapin, AI (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 183-301, Pasadena, CA 91109 USA. RI ID, MRCAT/G-7586-2011 NR 48 TC 32 Z9 35 U1 2 U2 13 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 2000 VL 147 IS 1 BP 68 EP 78 DI 10.1006/icar.2000.6437 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349WG UT WOS:000089068100007 ER PT J AU Scheeres, DJ Ostro, SJ Werner, RA Asphaug, E Hudson, RS AF Scheeres, DJ Ostro, SJ Werner, RA Asphaug, E Hudson, RS TI Effects of gravitational interactions on asteroid spin states SO ICARUS LA English DT Article ID ANGULAR-MOMENTUM; DESPINNING ASTEROIDS; ORBITS; DISRUPTION; TOUTATIS; DYNAMICS AB We demonstrate that mutual gravitational interactions between an asteroid and a planet or another asteroid can play an important role in shaping an asteroid's spin state. We focus on two situations that asteroids may encounter during their lifetimes. The first is the environment after creation from a disrupted parent asteroid, when there may be many asteroid fragments interacting gravitationally with each other before their mutual escape. The other is the interaction between an asteroid and a planet during a hyperbolic flyby. In each case the mutual gravitational interaction can alter the asteroid's spin state. We derive analytical descriptions of the effects and perform numerical simulations to explore the interactions and to give examples, The net effect of many small interactions, taken in isolation, is to cause the asteroid to spin at a faster rate-although this must be balanced against all other effects that influence spin rates. Conversely, the effect of a single, strong interaction can fundamentally change an asteroid's spin state, causing it to tumble and significantly increasing or decreasing its overall angular momentum. We simulate interactions of a sphere of arbitrary mass with Toutatis and find that these types of gravitational interactions can provide partial explanations for the current Toutatis rotational state. (C) 2000 Academic Press. C1 Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Santa Cruz, Dept Earth Sci, Santa Cruz, CA 95064 USA. Washington State Univ, Sch Elect Engn & Comp Sci, Pullman, WA 99164 USA. RP Scheeres, DJ (reprint author), Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. NR 21 TC 50 Z9 50 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 2000 VL 147 IS 1 BP 106 EP 118 DI 10.1006/icar.2000.6443 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349WG UT WOS:000089068100010 ER PT J AU Vilas, F Cochran, AL Jarvis, KS AF Vilas, F Cochran, AL Jarvis, KS TI Vesta and the Vestoids: A new rock group? SO ICARUS LA English DT Article DE asteroids; asteroids, composition; asteroids, Vesta; spectrophotometry; surfaces, asteroids ID ASTEROID 4-VESTA; PARENT BODY; NEAR-EARTH; METEORITES; HOWARDITE; SURFACE; EUCRITE; DIOGENITES; SPECTRUM; ORIGIN AB Moderate spectral resolution observations of the 505-nm Fe2+ pyroxene absorption feature were obtained for 13 asteroids dynamically linked to 4 Vesta, or located between Vesta and the 3:1 resonance gap. Eleven showed spectra with deep 0.9-mu m mafic silicate absorptions suggesting a pyroxene composition (Binzel and Xu 1993). Spectra of only six of these asteroids show the absorption feature centered at 506.5 nm, suggestive of an augite (high-calcium) component to the surface pyroxenes consistent with previous spectral observations across the surface of Vesta (Cochran and Vilas 1998). Five of the six asteroids include all objects observed at heliocentric distances between Vesta and the 3:1 resonance gap. The spectrum of only one asteroid interior to Vesta's orbit showed this feature. No correlation between the presence or absence of this feature and the strength of the 1-mu m mafic silicate feature was found. (C) 2000 Academic Press. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Texas, Austin, TX 78712 USA. Lockheed Martin Space Operat, Houston, TX 77058 USA. RP Vilas, F (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 27 TC 36 Z9 36 U1 2 U2 3 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD SEP PY 2000 VL 147 IS 1 BP 119 EP 128 DI 10.1006/icar.2000.6445 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349WG UT WOS:000089068100011 ER PT J AU Fernandez, YR Lisse, CM Kaufl, HU Peschke, SB Weaver, HA A'Hearn, MF Lamy, PP Livengood, TA Kostiuk, T AF Fernandez, YR Lisse, CM Kaufl, HU Peschke, SB Weaver, HA A'Hearn, MF Lamy, PP Livengood, TA Kostiuk, T TI Physical properties of the nucleus of Comet 2P/Encke SO ICARUS LA English DT Article DE comets; infrared observations ID NEAR-EARTH ASTEROIDS; CCD PHOTOMETRY; INFRARED OBSERVATIONS; OUTGASSING ASYMMETRY; RADAR OBSERVATIONS; THERMAL-MODEL; INNER COMA; ENCKE; ISOPHOT; HALLEY AB We report a new study of the nucleus of Comet 2P/Encke, which the CONTOUR spacecraft is scheduled to encounter in November 2003. During the comet's close approach to Earth in July 1997, we measured the mid-infrared thermal and optical scattered continua with data from the TIMMI instrument (imaging) at the ESO 3.6-m telescope (wavelength lambda from 8 to 12 mu m), the ISOPHOT instrument (photometry) aboard ISO (3.6 mu m less than or equal to lambda less than or equal to 100 mu m), and the STIS instrument (imaging) aboard HST (5500 Angstrom less than or equal to lambda less than or equal to 11000 Angstrom). The optical images show the nucleus with very little coma contamination, and the ISO photometry allowed us to separate the comatic and nuclear contributions to the ESO images. We used the Standard Thermal Model for slow rotators to calculate an effective nuclear radius of 2.4 km +/- 0.3 km. The comet's mid-IR light curve implies a nuclear rotation period of 15.2 h +/- 0.3 h, although some subharmonics of this also satisfy the data. If we assume that the nucleus is a triaxial ellipsoid in principal short axis rotation with the axis direction in 1985 as derived by Sekanina (1988, Astron. J. 95, 911), then by combining our data with light curves from the 1980s we find that the nucleus' angular momentum vector migrates, making a would-be circle in less than 81 years, and that one axial ratio is at least 2.6. The nucleus' optical linear phase coefficient is 0.06 mag/degree, making it one of the most phase-darkened objects known. The surface is also rougher than that of most asteroids, The visual geometric albedo is 0.05 +/- 0.02, within the range found for other cometary nuclei. (C) 2000 Academic Press. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Univ Hawaii Manoa, Astron Inst, Honolulu, HI 96822 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. European So Observ, D-85748 Garching, Germany. European Space Agcy, Satellite Tracking Stn, E-28080 Madrid, Spain. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. CNRS, Astron Spatiale Lab, F-13376 Marseille 12, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Fernandez, YR (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. EM yan@ifa.hawaii.edu RI Livengood, Timothy/C-8512-2012; Kostiuk, Theodor/A-3077-2014; Weaver, Harold/D-9188-2016; Lisse, Carey/B-7772-2016; OI Lisse, Carey/0000-0002-9548-1526; Fernandez, Yanga/0000-0003-1156-9721 NR 80 TC 79 Z9 80 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 SEP PY 2000 VL 147 IS 1 BP 145 EP 160 DI 10.1006/icar.2000.6431 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349WG UT WOS:000089068100013 ER PT J AU Cruikshank, DP Schmitt, B Roush, TL Owen, TC Quirico, E Geballe, TR de Bergh, C Bartholomew, MJ Ore, CMD Doute, S Meier, R AF Cruikshank, DP Schmitt, B Roush, TL Owen, TC Quirico, E Geballe, TR de Bergh, C Bartholomew, MJ Ore, CMD Doute, S Meier, R TI Water ice on Triton SO ICARUS LA English DT Article DE Triton; spectroscopy; ices; infrared observations; satellites of Neptune; surfaces, satellite ID COMET HALE-BOPP; SOLAR-SYSTEM; SURFACE; STATE; ABSORPTION; NITROGEN; FROST; SUN AB We discuss the spectroscopic detection of H(2)O ice on Triton, evidenced by the broad absorption bands in the near infrared at 1.55 and 2.04 mu m. The detection of water ice on Triton reconfirms earlier preliminary studies (D. P. Cruikshank et al. 1984, Icarus 58, 293-305). Although crystalline H(2)O ice has a distinctive spectral band at 1.65 mu m, and our new models slightly favor the presence of this phase, we cannot unambiguously determine whether Triton's water ice is crystalline or amorphous. Both phases might be present, and special conditions in the surface microstructure may affect the spectroscopic signature of water ice in such a way that crystalline ice is present and its 1.65 mu m spectral band is masked. Our spectra (1.87-2.5 mu m) taken at an interval of nearly 3.5 years do not show any significant changes that might relate to reports of changes in Triton's spectral reflectance (B. Buratti et al. 1999, Nature 397, 219), or in Triton's surface pressure (J. L. Elliot et al. 1998, Nature 393, 765-767). (C) 2000 Academic Press. C1 NASA, Ames Res Ctr, Astrophys Branch, Moffett Field, CA 94035 USA. Lab Planetol Grenoble, F-38041 Grenoble 9, France. NASA, Ames Res Ctr, Planetary Syst Branch, Moffett Field, CA 94035 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Univ Paris 11, Inst Astrophys Spatiale, F-91405 Orsay, France. Gemini Observ, Hilo, HI 96720 USA. Observ Paris, Sect Astrophys, F-92195 Meudon, France. Sterling Software Inc, Palo Alto, CA 94303 USA. SETI Inst, Mountain View, CA 94043 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. RP Cruikshank, DP (reprint author), NASA, Ames Res Ctr, Astrophys Branch, MS 245-6, Moffett Field, CA 94035 USA. EM dale@ssa1.arc.nasa.gov RI Schmitt, Bernard/A-1064-2009; quirico, eric/K-9650-2013 OI Schmitt, Bernard/0000-0002-1230-6627; quirico, eric/0000-0003-2768-0694 NR 46 TC 34 Z9 34 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 SEP PY 2000 VL 147 IS 1 BP 309 EP 316 DI 10.1006/icar.2000.6451 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 349WG UT WOS:000089068100023 ER PT J AU Calhoun, CC AF Calhoun, CC TI Identifying and managing risks for Automatic Test Systems SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB Risk is the possibility of suffering loss. In a development project, the loss describes the impact to the project which could be in the form of diminished quality of the end-product, increased costs, delayed completion, or failure. This paper discusses the methods and techniques for identifying and managing the risks involved with Automatic Test Systems development. C1 NASA, Independent Verificat & Validat Facil, Fairmont, WV 26554 USA. RP Calhoun, CC (reprint author), NASA, Independent Verificat & Validat Facil, 100 Univ Dr, Fairmont, WV 26554 USA. NR 8 TC 1 Z9 1 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 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD SEP PY 2000 VL 15 IS 9 BP 9 EP 12 DI 10.1109/62.873469 PG 4 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA 358UM UT WOS:000089575600005 ER PT J AU Kao, DL Ma, KL AF Kao, DL Ma, KL TI The life cycle of a visualization case study SO IEEE COMPUTER GRAPHICS AND APPLICATIONS LA English DT Editorial Material C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Davis, Davis, CA 95616 USA. RP Kao, DL (reprint author), NASA, Ames Res Ctr, M-S T27A-2, Moffett Field, CA 94035 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 0272-1716 J9 IEEE COMPUT GRAPH JI IEEE Comput. Graph. Appl. PD SEP-OCT PY 2000 VL 20 IS 5 BP 29 EP 31 DI 10.1109/MCG.2000.865876 PG 3 WC Computer Science, Software Engineering SC Computer Science GA 347EN UT WOS:000088914600007 ER PT J AU Hughes, RJ Williams, CP AF Hughes, RJ Williams, CP TI Quantum computing: The final frontier? SO IEEE INTELLIGENT SYSTEMS & THEIR APPLICATIONS LA English DT Editorial Material ID COMPUTATION; ALGORITHM; CRYPTOGRAPHY C1 Los Alamos Natl Lab, Div Phys, Los Alamos, NM 87545 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Stanford Univ, Stanford, CA 94305 USA. RP Los Alamos Natl Lab, Div Phys, Los Alamos, NM 87545 USA. EM hughes@lanl.gov; colin.p.williams@jpl.nasa.gov NR 29 TC 4 Z9 4 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1094-7167 J9 IEEE INTELL SYST APP JI IEEE Intell. Syst. Appl. PD SEP-OCT PY 2000 VL 15 IS 5 BP 10 EP 18 DI 10.1109/5254.889102 PG 9 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 376UE UT WOS:000165474500004 ER PT J AU Ghaffarian, R Kim, NP AF Ghaffarian, R Kim, NP TI Reliability and failure analyses of thermally cycled ball grid array assemblies SO IEEE TRANSACTIONS ON COMPONENTS AND PACKAGING TECHNOLOGIES LA English DT Article DE ball grid array; EGA; CBGA; PBGA; solder joint reliability; thermal cycling AB Reliability of ball grid arrays (BGAs) was assessed as part of a consortium effort led by the Jet Propulsion Laboratory. Nearly 200 test vehicles, each with four packages, were assembled and tested using an experiment design, The most critical variables incorporated in for the experiment were package types, ceramic and plastic; board materials, FR-4 and polyimide; surface finishes, OSP, HASL, and Ni/Au; solder volumes, low standard, and high; and environmental conditions. Thermal cycling test results to 3000 cycles for ceramic packages with 625 inputs/outputs (I/Os) and depopulated full array plastic packages with 313 I/Os were presented in a previous paper [1], This paper will present the most current thermal cycling test results (>6000 cycles) for plastic OMPAC and SuperBGA packages with 352 I/Os and 560 I/Os, Failure mechanisms detected by electrical continuity interruptions as well as optical and scanning electron microscopy results will also be compared for ceramic and plastic package assemblies. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Boeing Informat Space & Def Syst, Seattle, WA 98124 USA. RP CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. EM Reza.Ghaffarian@jpl.nasa.gov NR 3 TC 12 Z9 12 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1521-3331 J9 IEEE T COMPON PACK T JI IEEE Trans. Compon. Packaging Technol. PD SEP PY 2000 VL 23 IS 3 BP 528 EP 534 DI 10.1109/6144.868853 PG 7 WC Engineering, Manufacturing; Engineering, Electrical & Electronic; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 355ZL UT WOS:000089418400016 ER PT J AU Lew, JS Lim, KB AF Lew, JS Lim, KB TI Robust control of identified reduced-interval transfer function SO IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY LA English DT Article DE interval polynomial analysis; modeling; parameter uncertainty; robust control; sensitivity analysis ID SPACE STRUCTURES AB In this paper, we propose and demonstrate the use of a reduced-interval transfer function for robust control design of a system with parametric uncertainty. A singular value decomposition technique is used to model a system with parametric uncertainty via an interval transfer function, where each interval represents one bounded uncertainty parameter. The interval lengths can be used to determine the number of intervals of the reduced-interval transfer function, which is used to form an uncertainty structure for application in robust control such as p-synthesis. A major benefit of working with a reduced-interval model is the simplicity and computational efficiency in analyzing and designing the robust controller. Also the order of the designed controller may be significantly reduced by using a reduced-interval model. To verify the system performance of the designed controller based on the reduced-interval model, we present a combined algorithm consisting of a sensitivity analysis and interval polynomial techniques. C1 Tennessee State Univ, Ctr Excellence Informat Syst, Nashville, TN 37203 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Lew, JS (reprint author), Tennessee State Univ, Ctr Excellence Informat Syst, Nashville, TN 37203 USA. NR 15 TC 4 Z9 4 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 1063-6536 J9 IEEE T CONTR SYST T JI IEEE Trans. Control Syst. Technol. PD SEP PY 2000 VL 8 IS 5 BP 833 EP 841 DI 10.1109/87.865855 PG 9 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA 506WV UT WOS:000172995500008 ER PT J AU De Grandi, G Mayaux, P Rauste, Y Rosenqvist, A Simard, M Saatchi, SS AF De Grandi, G Mayaux, P Rauste, Y Rosenqvist, A Simard, M Saatchi, SS TI The Global Rain Forest Mapping Project JERS-1 radar mosaic of tropical Africa: Development and product characterization aspects SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT International Geoscience and Remote Sensing Symposium (IGARSS 99) CY JUN 28-JUL 02, 1999 CL HAMBURG, GERMANY DE calibration; geometric modeling; image classification; radar applications; radar cross sections; radar data processing; radar signal analysis; synthetic aperture radar (SAR); tropical regions; vegetation mapping; wavelet transforms ID DEFORESTATION; DECOMPOSITION; AMAZON AB The Global Rain Forest Mapping Project (GRFM) is an international collaborative effort initiated and managed by the National Space Development Agency of Japan (NASDA), The main goal of the project is to produce a high resolution wall-to-wall map of the entire tropical rain forest domain in four continents using the L-band SAR onboard the JERS-1 spacecraft. The processing phase, which entails the generation of wide area radar mosaics from the raw SAR data, was split according to the geographic area, In this paper, the focus is on the part related to Africa. The GRFM project's goal calls for the coverage of a continental scale area of several million km(2) using a sensor with the resolution of tens of meters. In the case of the African continent, this entails the assemblage of some 3900 high resolution SAR scenes into a bitemporal mosaic at 100 m pixel spacing and with known geometric accuracy. While this fact opens up an entire new perspective for vegetation mapping in the tropics, it presents a number of technical challenges, In this paper, we report on the solutions adopted in the GRFM Africa mosaic development and discuss some quantitative and qualitative aspects related to the characterization and validation of the GRFM products. In particular, the mosaic geolocation and its validation are discussed in detail. Indeed, the internal geometric consistency (subpixel accuracy in the coregistration of the two dates), and the absolute geolocation (residual mean squared error of 240 m with respect to ground control points) are key features of the GRFM Africa mosaic. Other important aspects that are discussed are the multiresolution decomposition approach, which allows for tracking the evolution of natural phenomena with scale; the internal semi-automatic radiometric calibration, which minimizes artifacts in the mosaic; and the thematic information content for vegetation mapping, which is illustrated by a few examples elaborated by visual interpretation, Experience gained so far indicates that the GRFM products constitute an important source of information for global environmental studies. C1 VARESE, Space Applicat Inst, Global Vegetat Monitoring Unit, European Commiss,Joint Res Ctr, Ispra, Italy. JRC, Space Applicat Inst, Ispra, Italy. Jet Prop Lab, Pasadena, CA 91109 USA. RP De Grandi, G (reprint author), VARESE, Space Applicat Inst, Global Vegetat Monitoring Unit, European Commiss,Joint Res Ctr, Ispra, Italy. EM frank.de-grandi@jrc.it RI Mitchard, Edward/C-6346-2009; Simard, Marc/H-3516-2013 OI Simard, Marc/0000-0002-9442-4562 NR 28 TC 39 Z9 39 U1 1 U2 8 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 2000 VL 38 IS 5 BP 2218 EP 2233 DI 10.1109/36.868880 PN 1 PG 16 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 357PP UT WOS:000089510300015 ER PT J AU Simard, M Saatchi, SS De Grandi, G AF Simard, M Saatchi, SS De Grandi, G TI The use of decision tree and multiscale texture for classification of JERS-1 SAR data over tropical forest SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article; Proceedings Paper CT International Geoscience and Remote Sensing Symposium (IGARSS 99) CY JUN 28-JUL 02, 1999 CL HAMBURG, GERMANY DE decision tree; forest; multiscale; synthetic aperture radar (SAR) ID IMAGING RADARS; LAND-COVER; VEGETATION; SEGMENTATION; DECOMPOSITION; SATELLITE; BIOMASS; IMAGERY AB The objective of this paper is to study the use of a decision tree classifier and multiscale texture measures to extract thematic information on the tropical vegetation cover from the Global Rain Forest Mapping (GRFM) JERS-1 SAR mosaics. We focus our study on a coastal region of Gabon, which has a variety of land cover types common to most tropical regions. A decision tree classifier does not assume a particular probability density distribution of the input data, and is thus well adapted for SAR image classification. A total of seven features, including wavelet-based multiscale texture measures (at scales of 200, 400, and 800 m) and multiscale multitemporal amplitude data (two dates at scales 100 and 400 m), are used to discriminate the land cover classes of interest. Among these layers, the best features for separating classes are found by constructing exploratory decision trees from various feature combinations. The decision tree structure stability is then investigated by interchanging the role of the training samples for decision tree growth and testing. We show that the construction of exploratory decision trees can improve the classification results. The analysis also proves that the radar backscatter amplitude is important for separating basic land cover categories such as savannas, forests, and flooded vegetation. Texture is found to be useful for refining flooded vegetation classes. Temporal information from SAR images of two different dates is explicitly used in the decision tree structure to identify swamps and temporarily flooded vegetation. C1 Jet Prop Lab, Pasadena, CA 91109 USA. Jet Prop Lab, Radar Sci & Engn Sect, Pasadena, CA 91109 USA. Joint Res Ctr, Space Applicat Inst, Ispra, VA, Italy. RP Simard, M (reprint author), Jet Prop Lab, Pasadena, CA 91109 USA. RI Simard, Marc/H-3516-2013 OI Simard, Marc/0000-0002-9442-4562 NR 29 TC 104 Z9 112 U1 0 U2 23 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 SEP PY 2000 VL 38 IS 5 BP 2310 EP 2321 DI 10.1109/36.868888 PN 1 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 357PP UT WOS:000089510300023 ER PT J AU Franceschetti, G Iodice, A Maddaluno, S Riccio, D AF Franceschetti, G Iodice, A Maddaluno, S Riccio, D TI Effect of antenna mast motion on X-SAR/SRTM performance SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE synthetic aperture radar (SAR); SAR interferometry ID INTERFEROMETRY; RADAR; SAR AB A prelaunch study on performances of the X-SAR/SRTM mission in case of outboard antenna mast bending is presented. The paper provides the assessment of SAR products, raw data complex images, and interferograms. Theoretical analysis shows the influence of mast oscillation parameters on each SAR product. Employing a SAR raw data simulator, a numerical study on canonical as well as actual scenes is also presented, Numerical results confirm theoretical analysis and quantitatively show SAR products degradation. C1 Jet Prop Lab, Pasadena, CA 91109 USA. Univ Naples Federico II, Dipartimento Ingn Elettr & Telecomun, Naples, Italy. CNR, IRECE, I-80125 Naples, Italy. RP Franceschetti, G (reprint author), Jet Prop Lab, Pasadena, CA 91109 USA. OI Iodice, Antonio/0000-0001-6173-3601 NR 12 TC 11 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 SEP PY 2000 VL 38 IS 5 BP 2361 EP 2372 DI 10.1109/36.868892 PN 2 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 357PK UT WOS:000089509900002 ER PT J AU Prigent, C Wigneron, JP Rossow, WB Pardo-Carrion, JR AF Prigent, C Wigneron, JP Rossow, WB Pardo-Carrion, JR TI Frequency and angular variations of land surface microwave emissivities: Can we estimate SSM/T and AMSU emissivities from SSM/I emissivities? SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE ATOVS; microwave radiometry; surface emissivity ID MILLIMETER WAVELENGTHS; SOIL-MOISTURE; GHZ; TEMPERATURE; RETRIEVAL; VEGETATION AB To retrieve temperature and humidity profiles from special sensor microwave/temperature (SSM/T) and advanced microwave sounding units (AMSU), it is important to quantify the contribution of the Earth surface emission. So far, no global estimates of the land surface emissivities are available at SSM/T and AMSU frequencies and scanning conditions. The land surface emissivities have been previously calculated for the globe from the SSM/I conical scanner between 19 and 85 GHz, To analyze the feasibility of deriving SSM/T and AMSU land surface emissivities from SSM/I emissivities, the spectral and angular variations of the emissivities are studied, with the help of ground-based measurements, models, and satellite estimates, Up to 100 GHz, for snow and ice free areas, the SSM/T and AMSU emissivities can be derived with useful accuracy from the SSM/I emissivities, The emissivities can be linearly interpolated in frequency. Based on ground-based emissivity measurements of various surface types, a simple model is proposed to estimate SSM/T and AMSU emissivities for all zenith angles knowing only the emissivities for the vertical and horizontal polarizations at 53 degrees zenith angle. The method is tested on the SSM/T-2 91.655 GHz channels. The mean difference between the SSM/T-2 and SSM/I-derived emissivities is less than or equal to 0.01 for all zenith angles with a root mean squared (RMS) difference of approximate to 0.02, Above 100 GHz, preliminary results are presented at 150 GHz based on SSM/T-2 observations and are compared with the very few estimations available in the literature. C1 Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. INRA, Bioclimatol Stn, Avignon, France. RP Prigent, C (reprint author), Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RI Rossow, William/F-3138-2015; OI wigneron, jean-pierre/0000-0001-5345-3618 NR 35 TC 47 Z9 52 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 2000 VL 38 IS 5 BP 2373 EP 2386 DI 10.1109/36.868893 PN 2 PG 14 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 357PK UT WOS:000089509900003 ER PT J AU Zhang, Y Tian, Y Knyazikhin, Y Martonchik, JV Diner, DJ Leroy, M Myneni, RB AF Zhang, Y Tian, Y Knyazikhin, Y Martonchik, JV Diner, DJ Leroy, M Myneni, RB TI Prototyping of MISR LAI and FPAR algorithm with POLDER data over Africa SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE fraction of photosynthetically active radiation; absorbed by vegetation (FPAR); leaf area index (LAI); multi-angle imaging spectroradiometer (MISR); multi-angle remote sensing; polarization and directionality of the Earth's; reflectance (POLDER); terra ID LEAF-AREA INDEX; PHOTOSYNTHETICALLY ACTIVE RADIATION; BOREAL CONIFER FORESTS; BIDIRECTIONAL REFLECTANCE; LAND; RETRIEVAL; FRACTION; CANOPIES AB The multi-angle imaging spectroradiometer (MISR) instrument is designed to provide global imagery at nine discrete viewing angles and four visible/near-infrared spectral hands. The MISR standard products include vegetation canopy green leaf area index (LAI) and fraction of photosynthetically active radiation absorbed by vegetation (FPAR), These products are produced using a peer-reviewed algorithm documented in the EOS-AMI (Terra) special issue of the Journal of Geophysical Research. This paper presents results on spatial distributions of LAI and FPAR of vegetated land surfaces derived from the MISR LAI/FPAR algorithm with bidirectional reflectance data from the polarization and directionality of the Earth's reflectance (POLDER) instrument over Africa. The results indicate that the proposed algorithm reflects the physical relationships between surface reflectances and biophysical parameters and demonstrates the advantages of using multi-angle data instead of single-angle data. A new method for evaluating bihemispherical reflectance (BHR) from multi-angle measurements of hemispherical directional reflectance factor (HDRF) was developed to prototype the algorithm with POLDER data. The accuracy of BHR evaluation and LAI/FPAR estimation is also presented, To demonstrate the advantages of using multi-angle data over single-angle data of surface reflectance, we demonstrate that: 1) the use of multi-angle data can decrease the dispersion and saturation of LAI, and increase the localization and quality of retrieved LAI and FPAR, 2) the use of multi-angle data can improve the accuracy of LAI retrievals in geometrically complex canopies such as shrubs, and 3) the use of multi-angle data can help determine biome or Land cover types correctly (by using the minimum value of LAI dispersion), For many other cases, we demonstrate that the use of multi-angle data does not lead to misevaluation, even if the land cover type is misidentified. C1 Boston Univ, Dept Geog, Boston, MA 02215 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Ctr Etud Spatiales Biosphere, Toulouse, France. RP Zhang, Y (reprint author), Boston Univ, Dept Geog, Boston, MA 02215 USA. RI Myneni, Ranga/F-5129-2012 NR 34 TC 21 Z9 23 U1 1 U2 11 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 SEP PY 2000 VL 38 IS 5 BP 2402 EP 2418 DI 10.1109/36.868895 PN 2 PG 17 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 357PK UT WOS:000089509900005 ER PT J AU Foster, JL Barton, JS Chang, ATC Hall, DK AF Foster, JL Barton, JS Chang, ATC Hall, DK TI Snow crystal orientation effects on the scattering of passive microwave radiation SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE dipole arrays; microwave radiometry; modeling; particle scattering crystals; position measurement ID DISCRETE-DIPOLE APPROXIMATION AB For this study, consideration is given to the role crystal orientation plays in scattering and absorbing microwave radiation. A discrete dipole scattering model is used to measure the passive microwave radiation at two polariztions (horizontal and vertical), scattered by snow crystals oriented in random and nonrandom positions and having various sizes (ranging from 1 mu m to 10 000 mu m in radius) and shapes (including spheres, cylinders, hexagons). The model results demonstrate that for the crystal sizes typically found in a snowpack, crystal orientation is insignificant compared to crystal size in terms of scattering microwave energy in the 8100 mu m (37 GHz) region of the spectrum, Therefore, the assumption used in radiative transfer approaches, where snow crystals are modeled as randomly oriented spheres, is adequate to account for the transfer of microwave energy emanating from the ground and passing through a snowpack. C1 NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. Gen Sci Corp, Beltsville, MD 20705 USA. RP Foster, JL (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RI Hall, Dorothy/D-5562-2012 NR 20 TC 2 Z9 4 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD SEP PY 2000 VL 38 IS 5 BP 2430 EP 2434 DI 10.1109/36.868899 PN 2 PG 5 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 357PK UT WOS:000089509900009 ER PT J AU Yueh, SH AF Yueh, SH TI Estimates of Faraday rotation with passive microwave polarimetry for microwave remote sensing of earth surfaces SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID BRIGHTNESS TEMPERATURES; RADIOMETER; SALINITY AB A technique based on microwave passive polarimetry for the estimates of ionospheric Faraday rotation for microwave remote sensing of Earth surfaces is described. Under the assumption of azimuth symmetry for the surfaces under investigation, it is possible to estimate the ionospheric Faraday rotation from the third Stokes parameter of microwave radiation. An error analysis shows that the Faraday rotation can be estimated with an accuracy of better than 10 with a space-based L-Band system, and the residual correction errors of linearly polarized brightness temperatures can be less than 0.1 K. it is suggested that the estimated Faraday rotation angle can be further utilized to derive the ionospheric total electron content (TEC) with an accuracy of about 1 TECU = 10(16) electrons-m(-2), which will yield 1 mm accuracy for the estimate of an ionospheric differential delay at Ku-band. Therefore, this technique can potentially provide accurate estimates of ionospheric Faraday rotation, TEC, and differential path delay far applications including microwave radiometry and scatterometry of ocean salinity and soil moisture as well as satellite altimetry of sea surface height. A conceptual design applicable to real aperture and aperture synthesis radiometers is described for the measurements of the third Stokes parameter. 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 19 TC 71 Z9 71 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 SEP PY 2000 VL 38 IS 5 BP 2434 EP 2438 DI 10.1109/36.868900 PN 2 PG 5 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 357PK UT WOS:000089509900010 ER PT J AU Rubaai, A Kankam, MD AF Rubaai, A Kankam, MD TI Adaptive tracking controller for induction motor drives using online training of neural networks SO IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS LA English DT Article; Proceedings Paper CT Annual Meeting of Industry-Applications-Society CY OCT 06-10, 1996 CL SAN DIEGO, CALIFORNIA SP Ind Applicat Soc DE adaptive learning; induction motor drives; neural networks; nonlinearity; online training ID SYSTEMS AB This paper explores means of controlling the dynamics of the stator currents of an induction motor. A neural-network-based identification and control scheme is presented. A single artificial neural network is trained to capture the nonlinear dynamics of the motor. A control law is derived using the dynamics captured by the network, and employed to force the stator currents to follow prescribed trajectories. The proposed architecture adapts and generalizes its learning to a wide variety of loads and, in addition provides the necessary abstraction when measurements are contaminated with noise. Extensive simulations reveal that neural designs are effective means of system identification and control for time-varying nonlinear systems, in the presence of uncertainty, The effects of parameter changes on the performance of the network is addressed. Particular emphasis is placed on the effects of sudden, random load torque changes. The difficulties addressed by this paper include incomplete system knowledge, nonlinearity; noise, and delays. C1 Howard Univ, Dept Elect Engn, Washington, DC 20059 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Rubaai, A (reprint author), Howard Univ, Dept Elect Engn, Washington, DC 20059 USA. NR 24 TC 7 Z9 7 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 0093-9994 J9 IEEE T IND APPL JI IEEE Trans. Ind. Appl. PD SEP-OCT PY 2000 VL 36 IS 5 BP 1285 EP 1294 DI 10.1109/28.871276 PG 10 WC Engineering, Multidisciplinary; Engineering, Electrical & Electronic SC Engineering GA 358QY UT WOS:000089569700013 ER PT J AU Romanofsky, RR Qureshi, AH AF Romanofsky, RR Qureshi, AH TI A model for ferroelectric phase shifters SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT International Magnetics Conference (INTERMAG 2000) CY APR 09-12, 2000 CL TORONTO, CANADA DE ferroelectricity; phase shifter circuits AB Novel microwave phase shifters consisting of coupled microstriplines on thin ferroelectric films have been demonstrated recently. A theoretical model useful for predicting the propagation characteristics (insertion phase shift, dielectric loss, impedance, and bandwidth) is presented here. The model is based on a variational solution for line capacitance and coupled strip transmission line theory. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Cleveland State Univ, Cleveland, OH 44135 USA. RP Romanofsky, RR (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 12 TC 17 Z9 17 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 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD SEP PY 2000 VL 36 IS 5 BP 3491 EP 3494 DI 10.1109/20.908870 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 409EN UT WOS:000167371700419 ER PT J AU Otoshi, TY Yeh, C AF Otoshi, TY Yeh, C TI Noise temperature of a lossy flat-plate reflector for the elliptically polarized wave-case SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article DE elliptical polarization; noise temperature; point; primer; reflector AB This short paper presents the derivation of equations necessary to calculate noise temperature of a lossy flat-plate reflector, Reflector losses can be due to metallic surface resistivity and multilayer dielectric sheets, including thin layers of plating, paint, and primer on the reflector surface. The incident wave is elliptically polarized, which is general enough to include linear and circular polarizations as well. The derivations show that the noise temperature for the circularly polarized incident wave ease is simply the average of those for perpendicular and parallel polarizations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Otoshi, TY (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NR 8 TC 1 Z9 1 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 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD SEP PY 2000 VL 48 IS 9 BP 1588 EP 1591 DI 10.1109/22.869014 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA 357CJ UT WOS:000089480700025 ER PT J AU Oliker, L Biswas, R AF Oliker, L Biswas, R TI Parallelization of a dynamic unstructured algorithm using three leading programming paradigms SO IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS LA English DT Article; Proceedings Paper CT 1999 Supercomputing Conference CY NOV 13-19, 1999 CL PORTLAND, OREGON DE distributed memory systems; CC-NUMA machines; multithreaded architectures; parallel implementation techniques; application performance studies; unstructured mesh adaptation AB The success of parallel computing in solving real-life computationally intensive problems relies on their efficient mapping and execution on large-scale multiprocessor architectures. Many important applications are both unstructured and dynamic in nature, making their efficient parallel implementation a daunting task. This paper presents the parallelization of a dynamic unstructured mesh adaptation algorithm using three popular programming paradigms on three leading supercomputers. We examine an MPI message-passing implementation on the Gray T3E and the SGI Origin2000, a shared-memory implementation using the cache coherent nonuniform memory access (CC-NUMA) feature of the Origin2000, and a multithreaded version on the newly released Tera Multithreaded Architecture (MTA). We compare several critical factors of this parallel code development, including runtime, scalability, programmability, portability, and memory overhead. Our overall results demonstrate that multithreaded systems offer tremendous potential for quickly and efficiently solving some of the most challenging real-life problems on parallel computers. C1 Univ Calif Berkeley, Lawrence Berkeley Lab, NERSC, Berkeley, CA 94720 USA. NASA, Comp Sci Corp, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Oliker, L (reprint author), Univ Calif Berkeley, Lawrence Berkeley Lab, NERSC, MS 50F, Berkeley, CA 94720 USA. NR 10 TC 18 Z9 18 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 1045-9219 J9 IEEE T PARALL DISTR JI IEEE Trans. Parallel Distrib. Syst. PD SEP PY 2000 VL 11 IS 9 BP 931 EP 940 DI 10.1109/71.879776 PG 10 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 368VA UT WOS:000090137100006 ER PT J AU Olson, CF AF Olson, CF TI Adaptive-scale filtering and feature detection using range data SO IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE LA English DT Article DE filtering; edge detection; feature detection; stereo; smoothing; scale-space ID EDGE-DETECTION; SELECTION; VISION; SPACE AB In edge and corner detection applications, it is typical to examine a single scale without knowing which scale is appropriate for each location in the image. However, many images contain a wide variation in the distance to the scene pixels and, thus, features of the same size can appear at greatly differing scales in the image. We present a method where the scale of the filtering and feature detection is Varied locally according to the distance to the scene pixel, which we estimate through stereoscopy. The features that are detected are, thus, at the same scale in the world. rather than at the same scale in the image. This method has been implemented efficiently by filtering the image at a discrete set of scales and performing interpolation to estimate the response at the correct scale for each pixel. The application of this technique to an ordnance recognition problem has resulted in a considerable improvement in performance. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Olson, CF (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 24 TC 16 Z9 18 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 0162-8828 J9 IEEE T PATTERN ANAL JI IEEE Trans. Pattern Anal. Mach. Intell. PD SEP PY 2000 VL 22 IS 9 BP 983 EP 991 DI 10.1109/34.877521 PG 9 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 361TY UT WOS:000089741300006 ER PT J AU Keymeulen, D Zebulum, RS Jin, Y Stoica, A AF Keymeulen, D Zebulum, RS Jin, Y Stoica, A TI Fault-tolerant evolvable hardware using field-programmable transistor arrays SO IEEE TRANSACTIONS ON RELIABILITY LA English DT Article DE evolvable hardware; fault tolerance; genetic algorithm; hardware-software co-design ID ANALOG AB The paper presents an evolutionary approach to the design of fault-tolerant VLSI (very large scale integrated) circuits using EHW (evolvable hardware). The EHW research area comprises a set of applications where GA (genetic algorithm) are used for the automatic synthesis and adaptation of electronic circuits. EHW is particularly suitable for applications requiring changes in task requirements and in the environment or faults, through its ability to reconfigure the hardware structure dynamically and autonomously, This capacity for adaptation is achieved via the use of GA search techniques. In our experiments, a fine-grained CMOS (complementary metal-oxide silicon) FPTA (field-programmable transistor array) architecture is used to synthesize electronic circuits, The FPTA is a reconfigurable architecture, programmable at the transistor level and specifically designed for EHW applications. The paper demonstrates the power of EA to design analog and digital fault-tolerant circuit. It compares two methods to achieve fault-tolerant design, one based on fitness definition and the other based on population. The fitness approach defines, explicitly, the faults that the component can encounter during its life, and evaluates the average behavior of the individuals. The population approach, on the other hand, uses the implicit information of the population statistics accumulated by the GA over many generations. The paper presents experiment results obtained using both approaches for the synthesis of a fault-tolerant digital circuit (XNOR) and a fault-tolerant analog circuit (multiplier), The experiments show that the EA (evolutionary algorithm) can synthesize fault-tolerant designs for both the analog and digital functions circuits that can recover for functionality when lost due to a-priori unknown faults by finding new circuit configurations that circumvent the faults. The paper shows that although the classic fault-tolerant design approach is able to create a reliable circuit design by evaluating the behavior of the circuit when well known faults are injected during the evolutionary process, better circuit performance, in less computation time, for a same fault-tolerant degree is achieved by allowing the evolutionary design process to be free of all faults constraints. C1 Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. RP Jet Prop Lab, M-S 303-300, Pasadena, CA 91109 USA. EM Didier.Keymeulen@jpl.nasa.gov; Ricardo.Zebulum@jpl.nasa.gov; Yili.Tin@caltech.edu NR 34 TC 64 Z9 71 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9529 EI 1558-1721 J9 IEEE T RELIAB JI IEEE Trans. Reliab. PD SEP PY 2000 VL 49 IS 3 BP 305 EP 316 DI 10.1109/24.914547 PG 12 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 418JH UT WOS:000167886800007 ER PT J AU Dick, GJ Wang, RT AF Dick, GJ Wang, RT TI Stability and phase noise tests of two cryo-cooled sapphire oscillators SO IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL LA English DT Article; Proceedings Paper CT Joint Meeting of the European-Frequency-and-Time-Forum/IEEE International Frequency Control Symposium CY APR 13-16, 1999 CL BESANCON, FRANCE SP Soc Francaise Microtechn & Chronometrie, IEEE AB A cryocooled compensated sapphire oscillator (CSO), developed for the Cassini Ka-band Radio Science experiment, and operating in the 7 K-10 K temperature range, was demonstrated to show ultra-high stability of sigma(y) = 2.5 X 10(-15) for measuring times 200 seconds less than or equal to tau less than or equal to 600 seconds using a hydrogen maser as a reference. CSO-1 and CSO-3 are now both operational with new low noise receivers. We have made initial phase noise and Allan deviation measurements that show more than 10 times stability improvement over the hydrogen maser for measuring times 1 second less than or equal to tau less than or equal to 10 seconds, and indicate performance for the individual units of sigma(y) approximate to 3 x 10(-15) for measuring times from 10 to 1000 seconds. Phase noise is reduced by 20 to 28 dB over the design offset frequency range from 1 Hz to 40 Hz. Receiver design is also discussed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Dick, GJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM john.dick@jpl.nasa.gov NR 6 TC 13 Z9 13 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0885-3010 J9 IEEE T ULTRASON FERR JI IEEE Trans. Ultrason. Ferroelectr. Freq. Control PD SEP PY 2000 VL 47 IS 5 BP 1098 EP 1101 DI 10.1109/58.869038 PG 4 WC Acoustics; Engineering, Electrical & Electronic SC Acoustics; Engineering GA 355EE UT WOS:000089372500003 PM 18238646 ER PT J AU Ko, YC Alouini, MS Simon, MK AF Ko, YC Alouini, MS Simon, MK TI Analysis and optimization of switched diversity systems SO IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY LA English DT Article; Proceedings Paper CT GLOBECOM 98 Conference CY NOV 08-12, 1998 CL SYDNEY, AUSTRALIA DE diversity combining; fading channels; switched diversity systems ID GENERALIZED-FADING CHANNELS; UNIFIED APPROACH; POLARIZATION DIVERSITY; DIGITAL-COMMUNICATION; PERFORMANCE ANALYSIS; RADIO PROPAGATION; 2-BRANCH SPACE; RAYLEIGH; ERROR; PROBABILITY AB We evaluate and optimize the performance of switch and stay diversity systems which have the advantage of offering one of the least complex solutions to mitigating the effect of Fading, We study the impart of fading type and severity, unbalanced branches, fading correlation, and imperfect channel estimation on the performance of these systems, and compare this performance with that of more complex diversity schemes such as maximal-ratio combining and selection combining. We also propose, analyze, and optimize the performance of a generalized switched diversity scheme. In summary, the presented results offer a simple, generic, and useful analytical tool for the accurate performance evaluation and optimization of switched diversity systems. C1 Univ Minnesota, Dept Elect & Comp Engn, Minneapolis, MN 55455 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ko, YC (reprint author), Univ Minnesota, Dept Elect & Comp Engn, Minneapolis, MN 55455 USA. NR 64 TC 110 Z9 112 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 0018-9545 J9 IEEE T VEH TECHNOL JI IEEE Trans. Veh. Technol. PD SEP PY 2000 VL 49 IS 5 BP 1813 EP 1831 DI 10.1109/25.892586 PG 19 WC Engineering, Electrical & Electronic; Telecommunications; Transportation Science & Technology SC Engineering; Telecommunications; Transportation GA 389UY UT WOS:000166258100034 ER PT J AU Kooi, JW Kawamura, J Chen, J Chattopadhyay, G Pardo, JR Zmuidzinas, J Phillips, TG Bumble, B Stern, J LeDuc, HG AF Kooi, JW Kawamura, J Chen, J Chattopadhyay, G Pardo, JR Zmuidzinas, J Phillips, TG Bumble, B Stern, J LeDuc, HG TI A low noise NbTiN-based 850 GHz SIS receiver for the Caltech Submillimeter Observatory SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article DE SIS receiver; twin-slot planar antenna; NbTiN superconductor; bandgap energy; AlN tunnel barrier; RF loss; and cooled optics ID MIXERS AB We have developed a niobium titanium nitride (NbTiN) based superconductor-insulator-superconductor (SIS) receiver to cover the 350 micron atmospheric window. This frequency band lies entirely above the energy gap of niobium (700 GHz), a commonly used SIS superconductor. The instrument uses an open structure twin-slot SIS mixer that consists of two Nb/AlN/NbTiN tunnel junctions, NbTiN thin-film microstrip tuning elements, and a NbTiN ground plane. The optical configuration is very similar to the 850 GHz waveguide receiver that was installed at the Caltech Submillimeter Observatory (CSO) in 1997. To minimize front-end loss, we employed reflecting optics and a cooled beamsplitter at 4 K. The instrument has an uncorrected receiver noise temperature of 205K DSB at 800 GHz and 410K DSB at 900 GHz. The degradation in receiver sensitivity with frequency is primarily due to an increase in the mixer conversion loss, which is attributed to the mismatch between the SIS junction and the twin-slot antenna impedance. The overall system performance has been confirmed through its use at the telescope to detect a wealth of new spectroscopic lines. C1 CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91108 USA. RP Kooi, JW (reprint author), CALTECH, Pasadena, CA 91125 USA. NR 21 TC 13 Z9 13 U1 0 U2 4 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0195-9271 J9 INT J INFRARED MILLI JI Int. J. Infrared Millimeter Waves PD SEP PY 2000 VL 21 IS 9 BP 1357 EP 1373 DI 10.1023/A:1026444721454 PG 17 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA 350TY UT WOS:000089118300001 ER PT J AU Doggett, WR Messner, WC Juang, JN AF Doggett, WR Messner, WC Juang, JN TI Multiple center of mass space images of single objects and their impact on path planning SO INTERNATIONAL JOURNAL OF ROBOTICS RESEARCH LA English DT Article DE robotic path planning; global optimization; center of mass space AB The center of mass space is a convenient space for planning motions that minimize reaction forces at the manipulator's base or optimize the stability of a mechanism. A unique problem associated with path planning in the center of mass space is the potential existence of multiple center of mass images for a single Cartesian obstacle, since a single center of mass location can correspond to multiple manipulator joint configurations. The existence of multiple images results in a need to either maintain multiple center of mass obstacle maps or to update obstacle locations when the manipulator passes through a singularity, such as when it moves from an elbow-up to an elbow-down configuration. To illustrate the concepts presented in this paper a path is planned for an example task requiring motion through multiple center of mass space maps. The object of the path-planning algorithm is to locate the path with a bang-bang acceleration profile that minimizes the manipulator's base reactions in the presence of a single Cartesian obstacle. To simplify the presentation, only nonredundant manipulators are considered and joint nonlinearities are neglected. C1 NASA, Langley Res Ctr, Syst Integrat Branch, Hampton, VA 23681 USA. Carnegie Mellon Univ, Dept Mech Engn, Pittsburgh, PA 15251 USA. NASA, Langley Res Ctr, Struct Dynam Branch, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, Syst Integrat Branch, Hampton, VA 23681 USA. NR 10 TC 1 Z9 1 U1 0 U2 1 PU SAGE PUBLICATIONS LTD PI LONDON PA 1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLAND SN 0278-3649 EI 1741-3176 J9 INT J ROBOT RES JI Int. J. Robot. Res. PD SEP PY 2000 VL 19 IS 9 BP 848 EP 856 DI 10.1177/02783640022067210 PG 9 WC Robotics SC Robotics GA 346BV UT WOS:000088851300004 ER PT J AU Lee, HJ Saravanos, DA AF Lee, HJ Saravanos, DA TI A mixed multi-field finite element formulation for thermopiezoelectric composite shells SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article DE adaptive structures; composite materials; finite element; laminates; piezoelectric; shell; smart structures; thermopiezoelectric ID EXACT PIEZOTHERMOELASTIC SOLUTION; INTELLIGENT STRUCTURES; ACTUATORS; PLATE; PANEL AB Analytical formulations are presented which account for the coupled mechanical, electrical, and thermal response of piezoelectric composite shell structures. A new mixed multi-field laminate theory is developed which combines "single layer" assumptions for the displacements along with layerwise fields for the electric potential and temperature. This laminate theory is formulated using curvilinear coordinates and is based on the principles of linear thermopiezoelectricity. The mechanics has the inherent capability to explicitly model both the active and sensory responses of piezoelectric composite shells in thermal environments. Finite element equations are derived and implemented for an eight-noded shell element. Numerical studies are conducted to investigate both the sensory and active responses of piezoelectric composite shell structures subjected to thermal loads. Results for a cantilevered plate with an attached piezoelectric layer are compared with corresponding results from a commercial finite element code and a previously developed program. Additional studies are conducted on a cylindrical shell with an attached piezoelectric layer to demonstrate capabilities to achieve thermal shape control on curved piezoelectric structures. Published by Elsevier Science Ltd. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Ohio Aerosp Inst, Cleveland, OH USA. RP Lee, HJ (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 25 TC 59 Z9 64 U1 1 U2 6 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 SEP PY 2000 VL 37 IS 36 BP 4949 EP 4967 DI 10.1016/S0020-7683(99)00192-4 PG 19 WC Mechanics SC Mechanics GA 323CP UT WOS:000087547500005 ER PT J AU Sarrazin, P Blake, D Bish, D Vaniman, D Chipera, S Collins, SA Elliott, ST AF Sarrazin, P Blake, D Bish, D Vaniman, D Chipera, S Collins, SA Elliott, ST TI In situ investigation of ices and hydrous minerals at the lunar poles using a combined X-ray fluorescence and diffraction instrument SO JOURNAL DE PHYSIQUE IV LA English DT Article; Proceedings Paper CT Conference on X-Rays and Matter (RX 99) CY DEC 07-10, 1999 CL ECOLE NATL SUPER ARTS & IND, STRASBOURG, FRANCE HO ECOLE NATL SUPER ARTS & IND ID WATER AB There is a growing body of evidence that points to the survival of water or hydrous minerals on the Moon and the potential for large aqueous reservoirs in shadowed craters at the lunar poles. CheMin, an XRD/XRF instrument that is currently under development, could provide a definitive test of whether the polar hydrogen signal measured by the recent Lunar Prospector mission is an indication of a significant water reservoir or merely reflects an anomalously rich accumulation of solar-wind hydrogen. Proposed enhancements of CheMin could be used in conjunction with a drilling system capable of penetrating the upper few tens of centimeters of the lunar regolith to search for ices or hydrous minerals. This advanced version of the CheMin instrument would be within the size, mass, and power constraints of Ariane 5 micromissions. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. ENESAD, F-21079 Dijon, France. Univ Calif Los Alamos Natl Lab, EES1, Los Alamos, NM 87545 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sarrazin, P (reprint author), NASA, Ames Res Ctr, MS 239-4, Moffett Field, CA 94035 USA. NR 12 TC 5 Z9 5 U1 0 U2 1 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 1155-4339 J9 J PHYS IV JI J. Phys. IV PD SEP PY 2000 VL 10 IS P10 BP 343 EP 352 DI 10.1051/jp4:20001037 PG 10 WC Physics, Multidisciplinary SC Physics GA 367HE UT WOS:000090055000037 ER PT J AU Wang, FY Proot, MMJ Charbonnier, JM Sforza, PM AF Wang, FY Proot, MMJ Charbonnier, JM Sforza, PM TI Near-field interaction of a jet with leading-edge vortices SO JOURNAL OF AIRCRAFT LA English DT Article ID AIRCRAFT; LIFT AB Results of the interaction between the vortex-wake of a 75-deg leading-edge sweep delta wing and a circular jet issuing from a tube parallel to the centerline of the wing are presented. Laser lightsheet flow visualizations and total pressure measurements were used to characterize the flowfield. In addition, a vortex-filament model used to supplement the examination of the streamwise evolution of jet exhaust in the presence of trailing vortices was shown to provide a reasonable qualitative description of the observed flow behavior. Visualization and total-pressure data revealed that introduction of large-scale persistent streamwise vortices substantially augments the jet spreading. Moreover, such an occurrence can be achieved within a short distance downstream. C1 Von Karman Inst Fluid Dynam, B-1640 Rhode St Genese, Belgium. Von Karman Inst Fluid Dynam, Dept Aeronaut & Aerosp, B-1640 Rhode St Genese, Belgium. Univ Florida, Grad Engn & Res Ctr, Shalimar, FL 32579 USA. RP Wang, FY (reprint author), NASA, John H Glenn Res Ctr, Mail Stop 86-7,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 29 TC 9 Z9 9 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 SEP-OCT PY 2000 VL 37 IS 5 BP 779 EP 785 DI 10.2514/2.2700 PG 7 WC Engineering, Aerospace SC Engineering GA 361MG UT WOS:000089726400005 ER PT J AU Schmitz, FH Aggarwal, HR Boxwell, DA AF Schmitz, FH Aggarwal, HR Boxwell, DA TI Prediction measurement of a low-frequency harmonic noise of hovering model helicopter rotor SO JOURNAL OF AIRCRAFT LA English DT Article ID DNW AB Far-field acoustic data for a model helicopter rotor have been gathered in a large, open-jet, acoustically treated wind tunnel with the rotor operating in hover and out of ground effect. The four-bladed Boeing 360 model rotor with advanced airfoils, planform, and tip shape was tested over a range of conditions typical of today's modern helicopter main rotor. Near in-plane acoustic measurements were compared with two independent implementations of classical linear acoustic theory, Measured steady thrust and torque were used together with a free-wake analysis (to predict the thrust and drag distributions along the rotor radius) as input to this first-principles theoretical approach. Good agreement between theory and experiment was shown at low frequencies (for both amplitude and phase) at those measurement locations where Low-frequency facility distortions were minimal. C1 Univ Maryland, Dept Aerosp Engn, College Pk, MD 20742 USA. Helicopter Aerodynam & Noise, Mountain View, CA 94040 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Schmitz, FH (reprint author), Univ Maryland, Dept Aerosp Engn, College Pk, MD 20742 USA. NR 22 TC 4 Z9 4 U1 0 U2 2 PU AMER INST AERONAUTICS ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0021-8669 EI 1533-3868 J9 J AIRCRAFT JI J. Aircr. PD SEP-OCT PY 2000 VL 37 IS 5 BP 786 EP 795 DI 10.2514/2.2701 PG 10 WC Engineering, Aerospace SC Engineering GA 361MG UT WOS:000089726400006 ER PT J AU Pirzadeh, SZ AF Pirzadeh, SZ TI A solution-adaptive unstructured grid method by grid subdivision and local remeshing SO JOURNAL OF AIRCRAFT LA English DT Article AB An adaptive unstructured grid refinement technique has been developed and successfully applied to several three-dimensional inviscid dow test cases. The method Is based on a combination of surface mesh subdivision and local remeshing of the volume grid, Simple functions of flow quantities are employed to detect dominant features of the flowfield. The method is designed for modular coupling with various error/feature analyzers and flow solvers. Several steady-state, inviscid flow test cases are presented to demonstrate the applicability of the method for solving practical three-dimensional problems. In all cases accurate solutions featuring complex, nonlinear flow phenomena such as shock waves and vortices have been generated automatically and efficiently. C1 NASA, Langley Res Ctr, Configurat Aerodynam Branch, Hampton, VA 23681 USA. RP Pirzadeh, SZ (reprint author), NASA, Langley Res Ctr, Configurat Aerodynam Branch, Hampton, VA 23681 USA. NR 11 TC 12 Z9 12 U1 0 U2 0 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 SEP-OCT PY 2000 VL 37 IS 5 BP 818 EP 824 DI 10.2514/2.2675 PG 7 WC Engineering, Aerospace SC Engineering GA 361MG UT WOS:000089726400010 ER PT J AU Rand, O Peyran, RJ AF Rand, O Peyran, RJ TI Experimental demonstration of the influence of wing couplings on whirl-flutter instability SO JOURNAL OF AIRCRAFT LA English DT Article ID TILTROTOR AB An experimental demonstration is presented of the influence and the effectiveness of tiltrotor wing couplings in postponing whirl-flutter instability in forward Eight. The experimental setup is based on a small-scale model where the wing supplies a coupled Elastic support hut does not introduce any aerodynamic contribution, The elastic deformation of the beam has been measured using a system of strain gauges at its root. Stability characteristics were calculated based on the recorded time history of the system response to an external abrupt disturbance. Beamwise bending-chordwise bending couplings were created by tilting the wing structure, whereas beamwise bending-twist couplings were introduced by changing the nacelle Length. Both types of the wing coupling effects were found influential. The results indicate that adequate exploiting of wing coupling effects has the potential to significantly improve the stability characteristics of coupled rotor-wing systems. C1 Technion Israel Inst Technol, Fac Aerosp Engn, IL-32000 Haifa, Israel. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Rand, O (reprint author), Technion Israel Inst Technol, Fac Aerosp Engn, IL-32000 Haifa, Israel. NR 40 TC 1 Z9 1 U1 1 U2 1 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 SEP-OCT PY 2000 VL 37 IS 5 BP 859 EP 864 DI 10.2514/2.2681 PG 6 WC Engineering, Aerospace SC Engineering GA 361MG UT WOS:000089726400016 ER PT J AU Jegley, DC AF Jegley, DC TI Response of selected integrally stiffened curved aluminum panels subjected to combined loads SO JOURNAL OF AIRCRAFT LA English DT Article AB The results of an analytical and experimental study of integrally stiffened curved aluminum panels are presented, A panel was tested and analyzed by applying an axial compressive load. The boundary and loading conditions for the panel were varied analytic ally to determine their effects on panel response. Elements representing clips between frames and longerons were added to evaluate the effect of these clips on the deformations of the panel. Panels were analyzed using a nonlinear finite element analysis. Axial compressive and internal pressure loads were analytically applied as individual loads and as combined loads. Strains and displacements, including the rotation of longerons, are compared. C1 NASA, Langley Res Ctr, Mech & Durabil Branch, Struct & Mat Competency, Hampton, VA 23681 USA. RP Jegley, DC (reprint author), NASA, Langley Res Ctr, Mech & Durabil Branch, Struct & Mat Competency, MS 190, Hampton, VA 23681 USA. NR 5 TC 1 Z9 1 U1 0 U2 0 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 SEP-OCT PY 2000 VL 37 IS 5 BP 880 EP 886 DI 10.2514/2.2684 PG 7 WC Engineering, Aerospace SC Engineering GA 361MG UT WOS:000089726400019 ER PT J AU Davila, CG Ambur, DR McGowan, DM AF Davila, CG Ambur, DR McGowan, DM TI Analytical prediction of damage growth in notched composite panels loaded in compression SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA/ASME/ASCE/AHS/ASC 40th Structures, Structural Dynamics, and Materials Conference CY APR 12-15, 1999 CL ST LOUIS, MISSOURI SP Amer Inst Aeronaut & Astronaut, ASME, ASCE, AHS, ASC ID LAMINATED COMPOSITES AB A progressive failure analysis method based on shell elements is developed for the computation of damage initiation and growth in stiffened, thick-skin, stitched graphite-epoxy panels loaded in axial compression. The analysis method involves a step-by-step simulation of material degradation based on ply-level failure mechanisms. High computational efficiency is derived from the use of superposed layers of shell elements to model each ply orientation in the laminate. Multiple integration points through the thickness are used to obtain the correct bending effects through the thickness without the need for ply-by-ply evaluations of the state of the material. The analysis results are compared with experimental results for three stiffened panels with notches oriented at 0, 15, and 30 deg to the panel width dimension. A parametric study is performed to investigate the damage growth retardation characteristics of the Kevlar(R) stitch lines in the panels. C1 USA,NASA, Res Lab,Langley Res Ctr, Struct Mech Branch, Vehicle Technol Directorate, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Struct Mech Branch, Hampton, VA 23681 USA. RP Davila, CG (reprint author), USA,NASA, Res Lab,Langley Res Ctr, Struct Mech Branch, Vehicle Technol Directorate, Hampton, VA 23681 USA. RI Davila, Carlos/D-8559-2011 NR 13 TC 10 Z9 11 U1 0 U2 4 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 SEP-OCT PY 2000 VL 37 IS 5 BP 898 EP 905 DI 10.2514/2.2688 PG 8 WC Engineering, Aerospace SC Engineering GA 361MG UT WOS:000089726400022 ER PT J AU Yang, S Smith, EA AF Yang, S Smith, EA TI Vertical structure and transient behavior of convective-stratiform heating in TOGA COARE from combined satellite-sounding analysis SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID MICROWAVE BRIGHTNESS TEMPERATURES; SPATIAL-RESOLUTION ENHANCEMENT; TROPICAL CLOUD CLUSTERS; MEASURING MISSION TRMM; MOISTURE BUDGETS; DECEMBER-1992 FEBRUARY-1993; STRUCTURE INFORMATION; RETRIEVAL ALGORITHM; ESTIMATING RAINFALL; WESTERN PACIFIC AB Datasets of daily high-resolution upper-air soundings and Special Sensor Microwave/Imager (SSM/I) passive microwave measurements from the Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) intensive operation period are used for large-scale diagnostic budget calculations of the apparent hear source (Q(1)), the apparent moisture sink (Q(2)), and latent heating to investigate the mechanisms of diabetic heating and moistening processes within the TOGA COARE Intensive Flux Array (IFA). Latent-heating retrievals are obtained from The Florida Slate University SSM/I-based precipitation profile retrieval algorithm. The estimates are correlated well with heating calculations from the soundings in which approximately 70% of the total heating arises from latent heat release. Moisture-budget processes also have a strong relationship with the large-scale environment, in which drying from condensation is mainly balanced by large-scale horizontal convergence of moisture flux. It is found that there may be more convective activity in summer than in winter over the tropical region of the western Pacific Ocean. Results also show that Q(1) and Q(2) exhibit a 20-30-day oscillation, in which active periods are associated with strong convection. Comparisons of the Q(1)-Q(2) calculations over IFA are made with a number of previously published results to help to establish the similarities and differences of Q(1)-Q(2) between the warm pool and other regions of the Tropics. The Q(1)-Q(2) budget analyses over IFA then are used to study quantitatively the detailed vertical heating structures. Cumulus-scale heating-moistening processes are obtained by using published radiative divergence (Q(R)) data, retrieved latent heating, and the Q(1)-Q(2) calculations. These results show that cumulus-scale turbulent transport is an important mechanism in both heat and moisture budgets. Although daily estimates of eddy vertical moisture flux divergence are noisy, by averaging over 7-day periods and vertically integrating to obtain surface latent heat flux, good agreement with measured surface evaporation is found. This agreement demonstrates the feasibility of estimating averaged eddy heat-moisture flux profiles by combining satellite-derived rain profile retrievals with large-scale sounding and Q(R) data, a methodology that helps to shed light on the role of cumulus convection in atmospheric heating and moistening. C1 Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. RP NASA, UAH, Global Hydrol & Climate Ctr, 977 Explorer Blvd, Huntsville, AL 35806 USA. EM eric.smith@msfc.nasa.gov NR 63 TC 19 Z9 19 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD SEP PY 2000 VL 39 IS 9 BP 1491 EP 1513 DI 10.1175/1520-0450(2000)039<1491:VSATBO>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 360KC UT WOS:000089665700006 ER PT J AU McCall, GE Grindeland, RE Roy, RR Edgerton, VR AF McCall, GE Grindeland, RE Roy, RR Edgerton, VR TI Muscle afferent activity modulates bioassayable growth hormone in human plasma SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE muscle spindle; vibration; soleus; tibialis anterior; extensor-flexor; slow-twitch muscle; fast-twitch muscle; proprioception; pituitary hormones ID RAT PITUITARY; CELL-FUNCTION; SPACEFLIGHT; VIBRATION; RELEASE; RESPONSES AB Immunoassayable and bioassayable growth hormone responses to vibration-induced activation of muscle spindle afferents of the soleus (Sol) or tibialis anterior (TA) muscles were studied in 10 men. Subjects were supine while a 10-min vibration stimulus (100 Hz; 1.5-mm amplitude) was applied to the muscle, with each of the muscles tested on separate days. Blood samples were collected before, during, immediately after, and after 5 and 10 min of vibration. Plasma growth hormone concentrations were determined by radioimmunoassay (IGH) for all sampling periods and by bioassay (BGH; measurement of tibial epiphysial cartilage growth in hypophysectomized rats) for samples obtained before and immediately after vibration. Plasma IGH concentrations were similar at all time points during the Sol or TA experiments. After 10 min of muscle vibration, mean plasma BGH was elevated 94% [1,216 +/- 148 (SD) to 2,362 +/- 487 mu g/l; P = 0.0001] for TA and decreased 22% (1,358 +/- 155 to 1,058 +/- 311 mu g/l; P = 0.09) for Sol. These data demonstrate that activation of TA muscle spindle afferents increases circulating BGH but not IGH. The absence of a similar vibration-induced BGH response for the Sol indicates a differential regulation of BGH release by these two predominantly slow muscles, perhaps related to their respective flexor and extensor functions. These data indicate that a muscle afferent-pituitary axis modulates the release of BGH, but not IGH, from the pituitary in humans and that this axis is muscle specific, similar to that observed in rats. C1 Univ Calif Los Angeles, Dept Physiol Sci, Los Angeles, CA 90095 USA. Univ Calif Los Angeles, Inst Brain Res, Los Angeles, CA 90095 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Edgerton, VR (reprint author), Univ Calif Los Angeles, Dept Physiol Sci, 621 Charles E Young Dr S, Los Angeles, CA 90095 USA. FU NIDCR NIH HHS [DE07212] NR 23 TC 35 Z9 41 U1 1 U2 2 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD SEP PY 2000 VL 89 IS 3 BP 1137 EP 1141 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 352DX UT WOS:000089200200036 PM 10956361 ER PT J AU Glenny, RW Lamm, WJE Bernard, SL An, D Chornuk, M Pool, SL Wagner, WW Hlastala, MP Robertson, HT AF Glenny, RW Lamm, WJE Bernard, SL An, D Chornuk, M Pool, SL Wagner, WW Hlastala, MP Robertson, HT TI Selected contribution: Redistribution of pulmonary perfusion during weightlessness and increased gravity SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE blood flow; microgravity; fluorescent microspheres; supine; prone ID BLOOD-FLOW DISTRIBUTION; SUSTAINED MICROGRAVITY; LUNG; POSITION; VOLUME; HUMANS; SLS-1 AB To compare the relative contributions of gravity and vascular structure to the distribution of pulmonary blood flow, we flew with pigs on the National Aeronautics and Space Administration KC-135 aircraft. A series of parabolas created alternating weightlessness and 1.8-G conditions. Fluorescent microspheres of varying colors were injected into the pulmonary circulation to mark regional blood flow during different postural and gravitational conditions. The lungs were subsequently removed, air dried, and sectioned into similar to 2 cm(3) pieces. Flow to each piece was determined for the different conditions. Perfusion heterogeneity did not change significantly during weightlessness compared with normal and increased gravitational forces. Regional blood flow to each lung piece changed little despite alterations in posture and gravitational forces. With the use of multiple stepwise linear regression, the contributions of gravity and vascular structure to regional perfusion were separated. We conclude that both gravity and the geometry of the pulmonary vascular tree influence regional pulmonary blood flow. However, the structure of the vascular tree is the primary determinant of regional perfusion in these animals. C1 Univ Washington, Sch Med, Dept Med, Seattle, WA 98195 USA. Univ Washington, Sch Med, Dept Physiol & Biophys, Seattle, WA 98195 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Indiana Univ, Sch Med, Dept Anesthesiol, Indianapolis, IN 46202 USA. Indiana Univ, Sch Med, Dept Physiol Biophys, Indianapolis, IN 46202 USA. Indiana Univ, Sch Med, Dept Pediat, Indianapolis, IN 46202 USA. RP Glenny, RW (reprint author), Karolinska Hosp & Inst, Dept Anesthesia & Intens Care, Bldg F2,00, SE-17176 Stockholm, Sweden. NR 28 TC 36 Z9 38 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD SEP PY 2000 VL 89 IS 3 BP 1239 EP 1248 PG 10 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 352DX UT WOS:000089200200050 PM 10956375 ER PT J AU Gizon, L Duvall, TL Larsen, RM AF Gizon, L Duvall, TL Larsen, RM TI Seismic tomography of the near solar surface SO JOURNAL OF ASTROPHYSICS AND ASTRONOMY LA English DT Article; Proceedings Paper CT IAU Colloquium on Cyclical Evolution of Solar Magnetic Fields CY DEC 13-16, 1999 CL KODAIKANAL OBSERV, KODAIKANAL, INDIA SP Int Astron Union HO KODAIKANAL OBSERV DE helioseismology; supergranulation; sunspots ID SUNSPOTS AB Surface gravity waves have been used to probe flows in the two megameters beneath the photosphere using the techniques of time-distance helioseismology. The results suggest that supergranule velocities are smaller than at the surface. The outward flow outside a sunspot penumbra (the meal) is observed, as is an inward flow in the region beyond the meal. C1 Stanford Univ, HEPL, Stanford, CA 94305 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Stanford Univ, SCCM, Stanford, CA 94305 USA. RP Gizon, L (reprint author), Stanford Univ, HEPL, Stanford, CA 94305 USA. RI Gizon, Laurent/B-9457-2008; Duvall, Thomas/C-9998-2012 NR 7 TC 70 Z9 70 U1 0 U2 0 PU INDIAN ACADEMY SCIENCES PI BANGALORE PA P B 8005 C V RAMAN AVENUE, BANGALORE 560 080, INDIA SN 0250-6335 J9 J ASTROPHYS ASTRON JI J. Astrophys. Astron. PD SEP-DEC PY 2000 VL 21 IS 3-4 BP 339 EP 342 DI 10.1007/BF02702420 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 403FV UT WOS:000167032600048 ER PT J AU Gopalswamy, N Shibasaki, K Salem, M AF Gopalswamy, N Shibasaki, K Salem, M TI Microwave enhancement in coronal holes: Statistical properties SO JOURNAL OF ASTROPHYSICS AND ASTRONOMY LA English DT Article; Proceedings Paper CT IAU Colloquium on Cyclical Evolution of Solar Magnetic Fields CY DEC 13-16, 1999 CL KODAIKANAL OBSERV, KODAIKANAL, INDIA SP Int Astron Union HO KODAIKANAL OBSERV DE Sun : radio radiation; coronal holes; EUV emission AB We report on the statistical properties of the microwave enhancement (brightness temperature, area, fine structure, life time and magnetic field strength) in coronal holes observed over a period of several solar rotations. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. Nobeyama Radio Observ, Minamisa Ku, Nagano 3841305, Japan. Case Western Reserve Univ, Dept Phys, Cleveland, OH 44106 USA. RP Gopalswamy, N (reprint author), NASA, Goddard Space Flight Ctr, Bldg 26,Room G-1,Code 682-3, Greenbelt, MD 20771 USA. RI Gopalswamy, Nat/D-3659-2012 NR 7 TC 10 Z9 10 U1 0 U2 0 PU INDIAN ACADEMY SCIENCES PI BANGALORE PA P B 8005 C V RAMAN AVENUE, BANGALORE 560 080, INDIA SN 0250-6335 J9 J ASTROPHYS ASTRON JI J. Astrophys. Astron. PD SEP-DEC PY 2000 VL 21 IS 3-4 BP 413 EP 417 DI 10.1007/BF02702435 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 403FV UT WOS:000167032600063 ER PT J AU Thejappa, G MacDowall, RJ AF Thejappa, G MacDowall, RJ TI Ulysses observations of nonlinear wave-wave interactions in the source regions of type III solar radio bursts SO JOURNAL OF ASTROPHYSICS AND ASTRONOMY LA English DT Article; Proceedings Paper CT IAU Colloquium on Cyclical Evolution of Solar Magnetic Fields CY DEC 13-16, 1999 CL KODAIKANAL OBSERV, KODAIKANAL, INDIA SP Int Astron Union HO KODAIKANAL OBSERV DE type III bursts; electrostatic decay; modulational instability ID EMISSION MECHANISMS AB The Ulysses Unified Radio and Plasma Wave Experiment (URAP) has observed Langmuir, ion-acoustic and associated solar type III radio emissions in the interplanetary medium. Bursts of 50-300 Hz (in the spacecraft frame) electric field signals, corresponding to long-wavelength ion-acoustic waves are often observed coincident in time with the most intense Langmuir wave spikes, providing evidence for the electrostatic decay instability. Langmuir waves often occur as envelope solitons, suggesting that strong turbulence processes, such as modulational instability and soliton formation, often coexist with weak turbulence processes, such as electrostatic decay, in a few type III burst source regions. 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 5 TC 0 Z9 0 U1 0 U2 0 PU INDIAN ACADEMY SCIENCES PI BANGALORE PA P B 8005 C V RAMAN AVENUE, BANGALORE 560 080, INDIA SN 0250-6335 J9 J ASTROPHYS ASTRON JI J. Astrophys. Astron. PD SEP-DEC PY 2000 VL 21 IS 3-4 BP 447 EP 450 DI 10.1007/BF02702442 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 403FV UT WOS:000167032600070 ER PT J AU Christy, JR Spencer, RW Braswell, WD AF Christy, JR Spencer, RW Braswell, WD TI MSU tropospheric temperatures: Dataset construction and radiosonde comparisons SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID MICROWAVE SOUNDING UNIT; SATELLITE; TRENDS; SURFACE; RECORDS; VALIDATION; PRECISION; ANOMALIES AB Two deep-layer tropospheric temperature products, one for the lower troposphere (T-2LT) and one for the midtroposphere (T-2, which includes some stratospheric emissions), are based on the observations of channel 2 of the microwave sounding unit on National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites. Revisions to version C of these datasets have been explicitly applied to account for the effects of orbit decay (loss of satellite altitude) and orbit drift (east-west movement). Orbit decay introduces an artificial cooling in T-2LT, while the effects of orbit drift introduce artificial warming in both T-2LT and T-2. The key issues for orbit drift are 1) accounting for the diurnal cycle and 2) the adjustment needed to correct for spurious effects related to the temperature of the instrument. In addition, new calibration coefficients for NOAA-12 have been applied. The net global effect of these revisions (version D) is small, having little impact on the year-to-year anomalies. The change in global trends from C to D for 1979-98 for T-2LT is an increase from +0.03 to +0.06 K decade(-1), and a decrease for T-2 from +0.08 to +0.04 K decade(-1). C1 Univ Alabama, GHCC, ESSC, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Nichols Res Corp, Huntsville, AL USA. RP Christy, JR (reprint author), Univ Alabama, GHCC, ESSC, Huntsville, AL 35899 USA. NR 28 TC 165 Z9 172 U1 0 U2 6 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD SEP PY 2000 VL 17 IS 9 BP 1153 EP 1170 DI 10.1175/1520-0426(2000)017<1153:MTTDCA>2.0.CO;2 PG 18 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA 362MY UT WOS:000089782800001 ER PT J AU Mayr, HG Mengel, JG Reddy, CA Chan, KL Porter, HS AF Mayr, HG Mengel, JG Reddy, CA Chan, KL Porter, HS TI Properties of QBO and SAO generated by gravity waves SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE QBO; SAO; wave filtering ID QUASI-BIENNIAL OSCILLATION; DOPPLER-SPREAD PARAMETERIZATION; TWO-DIMENSIONAL MODEL; MIDDLE ATMOSPHERE; SEMIANNUAL OSCILLATION; EQUATORIAL OSCILLATIONS; MOMENTUM DEPOSITION; ZONAL WIND; TROPICAL STRATOSPHERE; NUMERICAL-MODEL AB In this paper we present an extension for the 2D (zonal mean) version of our numerical spectral mode (NSM) that incorporates Hines' Doppler spread parameterization (DSP) for small-scale gravity waves (GW). This model is applied to describe the seasonal variations and the semi-annual and quasi-biennial oscillations (SAO and QBO). Our earlier model reproduced the salient features of the mean zonal circulation in the middle atmosphere, including the QBO extension into the upper mesosphere inferred from UARS measurements. The model is extended to reproduce the upwelling at equatorial latitudes that is associated with the Brewer-Dobson circulation - which affects significantly the dynamics of the stratosphere as Dunkerton had pointed out. In the presence of GW, this upwelling is produced in our model with tropospheric heating, which generates also zonal jets outside the tropics similar to those observed. The resulting upward vertical winds increase the period of the QBO. To compensate for that, one needs to increase the eddy diffusivity and the GW momentum flux, bringing the latter closer to values recommended in the DSP. The QBO period in the model is 30 months (mo), which is conducive to synchronize this oscillation with the seasonal cycle of solar forcing. Associated with this QBO are interannual and interseasonal variations that become increasingly more important at higher altitudes - and this variability is interpreted in terms of GW filtering that effectively couples the dynamical components of the mesosphere. The computed temperature amplitudes for the SAO and QBO are in substantial agreement with observations at equatorial and extra-tropical latitudes. At high latitudes, however, the observed QBO amplitudes are significantly larger, which may be a signature of propagating planetary waves not included in the present model. The assumption of hydrostatic equilibrium not being imposed, we find that the effects from the vertical Coriolis force associated with the equatorial oscillations are large for the vertical winds and significant for the temperature variations even outside the tropics, but the effects are small for the zonal winds. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Atmospher Chem & Dynam Branch, Greenbelt, MD 20771 USA. SM & A Corp, Vienna, VA 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, Atmospher Chem & Dynam Branch, Mail Code 910-4, Greenbelt, MD 20771 USA. OI Chan, Kwing/0000-0002-6428-1812 NR 63 TC 19 Z9 19 U1 1 U2 4 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 SEP PY 2000 VL 62 IS 13 BP 1135 EP 1154 DI 10.1016/S1364-6826(00)00103-6 PG 20 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 371HH UT WOS:000165172600002 ER PT J AU Tobiska, WK Woods, T Eparvier, F Viereck, R Floyd, L Bouwer, D Rottman, G White, OR AF Tobiska, WK Woods, T Eparvier, F Viereck, R Floyd, L Bouwer, D Rottman, G White, OR TI The SOLAR2000 empirical solar irradiance model and forecast tool SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT NOAA Space Weather Week Meeting CY APR 19-23, 1999 CL BOULDER, COLORADO SP NOAA, Space Environm Ctr, USAF Res Lab, Natl Sci Fdn DE solar spectrum; solar irradiances; solar EUV; SOLAR2000; space weather forecasts ID EUV FLUX MODEL; SOLSPEC SPECTROMETER; SPECTRAL IRRADIANCE; ULTRAVIOLET FLUX; VARIABILITY; NM AB SOLAR2000 is a collaborative project for accurately characterizing solar irradiance variability across the spectrum. A new image- and full-disk proxy empirical solar irradiance model, SOLAR2000, is being developed that is valid in the spectral range of 1-1,000,000 nm for historical modeling and forecasting throughout the solar system. The overarching scientific goal behind SOLAR2000 is to understand how the Sun varies spectrally and through time from X-ray through infrared wavelengths. This will contribute to answering key scientific questions and will aid national programmatic goals related to solar irradiance specification. SOLAR2000 is designed to be a fundamental energy input into planetary atmosphere models, a comparative model with numerical/first principles solar models, and a tool to model or predict the solar radiation component of the space environment, It is compliant with the developing International Standards Organization (ISO) solar irradiance standard. SOLAR2000 captures the essence of historically measured solar irradiances and this expands our knowledge about the quiet and variable Sun including its historical envelope of variability. The implementation of the SOLAR2000 is described, including the development of a new EUV proxy, E10.7, which has the same units as the commonly used F10.7. SOLAR2000 also provides an operational forecasting and global specification capability for solar irradiances and information can be accessed at the website address of http://www.spacenvironment.net. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, FDC, Pasadena, CA 91109 USA. Univ Colorado, LASP, Boulder, CO 80309 USA. NOAA, FDC, SEC, Boulder, CO 80303 USA. RP Tobiska, WK (reprint author), CALTECH, Jet Prop Lab, FDC, 4800 Oak Grove Dr,MS 264-580, Pasadena, CA 91109 USA. NR 45 TC 295 Z9 302 U1 5 U2 19 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 SEP PY 2000 VL 62 IS 14 BP 1233 EP 1250 DI 10.1016/S1364-6826(00)00070-5 PG 18 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 372VW UT WOS:000165255600003 ER PT J AU St Cyr, OC Mesarch, MA Maldonado, HM Folta, DC Harper, AD Davila, JM Fisher, RR AF St Cyr, OC Mesarch, MA Maldonado, HM Folta, DC Harper, AD Davila, JM Fisher, RR TI Space Weather Diamond: a four spacecraft monitoring system SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT NOAA Space Weather Week Meeting CY APR 19-23, 1999 CL BOULDER, COLORADO SP NOAA, Space Environm Ctr, USAF Res Lab, Natl Sci Fdn DE space weather monitoring system; solar wind ID WIND PLASMA CORRELATIONS; SOLAR AB We report here preliminary results of a mission analysis fur a space weather monitoring system that provides continuous transmission of solar wind conditions 0.10 A.U. upstream from Earth. The system is based on four platforms that are phased into eccentric heliocentric orbits but, from the perspective of a fixed Sun-Earth line, the spacecraft appear to orbit Earth. This system offers a 10x improvement in reporting solar wind plasma and magnetic field characteristics beyond similar platforms located at the Lagrangian L-1 point. We describe launch and energy considerations, along with a preliminary analysis of communication requirements. The Space Weather Diamond offers significant potential for scientific insight into problems requiring coordinated observations from multiple vantage points by providing the ability to separate spatial from temporal variations. We discuss examples for payloads including both in situ and remote sensing instrumentation. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP St Cyr, OC (reprint author), NASA, Goddard Space Flight Ctr, MS 682, Greenbelt, MD 20771 USA. NR 13 TC 2 Z9 2 U1 0 U2 0 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 SEP PY 2000 VL 62 IS 14 BP 1251 EP 1255 PG 5 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 372VW UT WOS:000165255600004 ER PT J AU LeBlanc, AD Lin, C Evans, HJ Shackelford, L Hedrick, T Udden, M AF LeBlanc, AD Lin, C Evans, HJ Shackelford, L Hedrick, T Udden, M TI Vertebral bone marrow changes following space flight. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 Baylor Coll Med, Houston, TX 77030 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Baylor Coll Med, Houston, TX 77030 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC BONE & MINERAL RES PI WASHINGTON PA 2025 M ST, N W, STE 800, WASHINGTON, DC 20036-3309 USA SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD SEP PY 2000 VL 15 SU 1 MA SU362 BP S419 EP S419 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA 346YJ UT WOS:000088898401135 ER PT J AU Topaler, MS Allison, TC Schwenke, DW Truhlar, DG AF Topaler, MS Allison, TC Schwenke, DW Truhlar, DG TI What is the best semiclassical method for photochemical dynamics of systems with conical intersections? (vol 109, pg 3321, 1998) SO JOURNAL OF CHEMICAL PHYSICS LA English DT Correction C1 Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA. Univ Minnesota, Inst Supercomp, Minneapolis, MN 55455 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Topaler, MS (reprint author), Univ Minnesota, Dept Chem, 207 Pleasant St SE, Minneapolis, MN 55455 USA. RI schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Truhlar, Donald/0000-0002-7742-7294 NR 1 TC 5 Z9 5 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD SEP 1 PY 2000 VL 113 IS 9 BP 3928 EP 3928 DI 10.1063/1.1286967 PG 1 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 346NR UT WOS:000088878400054 ER PT J AU Wang, JH Rossow, WB Zhang, YC AF Wang, JH Rossow, WB Zhang, YC TI Cloud vertical structure and its variations from a 20-yr global rawinsonde dataset SO JOURNAL OF CLIMATE LA English DT Article ID GENERAL-CIRCULATION MODEL; UPPER-AIR OBSERVATIONS; RELATIVE-HUMIDITY; OPTICAL-THICKNESS; ISCCP DATA; SATELLITE; RADIATION; CLIMATOLOGY; COMBINATION; ATMOSPHERE AB A global cloud vertical structure (CVS) climatic dataset is created by applying an analysis method to a 20-yr collection of twice-daily rawinsonde humidity profiles to estimate the height of cloud layers. The CVS dataset gives the vertical distribution of cloud layers for single and multilayered clouds, as well as the top and base heights and layer thicknesses of each layer, together with the original rawinsonde profiles of temperature, humidity, and winds. The average Values are cloud-top height = 4.0 km above mean sea level (MSL), cloud-base height = 2.4 km MSL, cloud-layer thickness = 1.6 km, and separation distance between consecutive layers = 2.2 km. Multilayered clouds occur 42% of the time and are predominately two-layered. The lowest layer of multilayered cloud systems is usually located in the atmospheric boundary layer (below 2-km height MSL). Clouds over the ocean occur more frequently at lower levels and are more often formed in multiple layers than over land. Latitudinal variations of CVS also show maxima and minima that correspond to the locations of the intertropical convergence zone, the summer monsoons, the subtropical subsidence zones, and the midlatitude storm zones. Multilayered clouds exist most frequently in the Tropics and least frequently in the subtropics; there are more multilayered clouds in summer than in winter. Cloud layers are thicker in winter than in summer at mid- and high latitudes, but are thinner in winter in Southeast Asia. C1 Natl Ctr Atmospher Res, SSSF, Boulder, CO 80307 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Appl Math & Phys, New York, NY USA. RP Wang, JH (reprint author), Natl Ctr Atmospher Res, SSSF, POB 3000, Boulder, CO 80307 USA. RI Rossow, William/F-3138-2015 NR 47 TC 96 Z9 106 U1 0 U2 11 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD SEP 1 PY 2000 VL 13 IS 17 BP 3041 EP 3056 DI 10.1175/1520-0442(2000)013<3041:CVSAIV>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 359GM UT WOS:000089603200001 ER PT J AU Fairbridge, RW AF Fairbridge, RW TI Fergus J. Wood (1917-2000) - In memorial SO JOURNAL OF COASTAL RESEARCH LA English DT Biographical-Item C1 Columbia Univ, NASA, GISS, New York, NY 10025 USA. RP Fairbridge, RW (reprint author), Columbia Univ, NASA, GISS, 2880 Broadway, New York, NY 10025 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU COASTAL EDUCATION & RESEARCH FOUNDATION PI LAWRENCE PA 810 EAST 10TH STREET, LAWRENCE, KS 66044 USA SN 0749-0208 J9 J COASTAL RES JI J. Coast. Res. PD FAL PY 2000 VL 16 IS 4 BP 1192 EP 1192 PG 1 WC Environmental Sciences; Geography, Physical; Geosciences, Multidisciplinary SC Environmental Sciences & Ecology; Physical Geography; Geology GA 384GY UT WOS:000165935500023 ER PT J AU Murray, BT Coriell, SR Chernov, AA McFadden, GB AF Murray, BT Coriell, SR Chernov, AA McFadden, GB TI The effect of oscillatory shear flow on step bunching SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE morphological stability; step motion; anisotropic kinetics; shear flow; floquet theory ID KINETIC SELF-STABILIZATION; MORPHOLOGICAL STABILITY; VICINAL FACE; BINARY ALLOY; GROWTH; SOLIDIFICATION; INSTABILITY; INTERFACE AB During crystal growth, an imposed shear Row at the crystal-fluid interface can alter the conditions for the onset of morphological instability. In previous work, we studied the effect of time-independent shear flows and anisotropic interface kinetics on the morphological stability of a crystal growing from supersaturated solution. The model assumes that growth is by the motion of elementary steps, which is treated by a macroscopic anisotropic kinetic law; morphological instability corresponds to the bunching of elementary steps. Predictions from linear stability theory indicate that a solution flowing above a vicinal face of a crystal can either enhance or prevent the development of step bunches, depending on the direction of the steady shear flow in relation to the direction of step motion: this is also observed in experiments. Here we extend the linear stability analysis to include the effect of an oscillatory shear flow on the morphological stability of a crystal growing from solution and present results for a model system for a range of oscillatory shear rate amplitudes and frequencies both with and without a steady shear component. In the presence of a steady shear flow, modulation can either stabilize or destabilize the system, depending on the modulation amplitude and frequency. Numerical solutions of the linearized Navier-Stokes and diffusion equations and an approximate analytical treatment Show that the flow oscillations weakens both the stabilization and destabilization induced by steady-state flow. This weakening comes from mixing of solution above the perturbed interface and a modification to the phase shift between the interface perturbation wave and the corresponding concentration and flow waves. Optimal values of modulation frequency and amplitude are found when the steady flow is destabilizing. (C) 2000 Elsevier Science B.V. AII rights reserved. C1 SUNY Binghamton, Dept Engn Mech, Binghamton, NY 13902 USA. Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA. Univ Space Res Assoc, Huntsville, AL 35806 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35806 USA. RP Murray, BT (reprint author), SUNY Binghamton, Dept Engn Mech, Binghamton, NY 13902 USA. RI McFadden, Geoffrey/A-7920-2008 OI McFadden, Geoffrey/0000-0001-6723-2103 NR 16 TC 14 Z9 16 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 SEP PY 2000 VL 218 IS 2-4 BP 434 EP 446 DI 10.1016/S0022-0248(00)00566-2 PG 13 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 358UH UT WOS:000089575200038 ER PT J AU Berejikian, BA Tezak, EP LaRae, AL AF Berejikian, BA Tezak, EP LaRae, AL TI Female mate choice and spawning behaviour of chinook salmon under experimental conditions SO JOURNAL OF FISH BIOLOGY LA English DT Article DE courtship behaviour; mate choice; Pacific salmon; intersexual communication ID TROUT ONCORHYNCHUS-MYKISS; ATLANTIC SALMON; PACIFIC SALMON; SOCKEYE-SALMON; REPRODUCTIVE-BEHAVIOR; BREEDING COMPETITION; SEXUAL SELECTION; MATURE MALE; BODY-SIZE; KISUTCH AB After spawning their first nest, female chinock salmon Oncorhynchus tshawytscha paired with small males (c. 46% of Female weight) spent an average of 16.2 h between spawning of successive nests compared with 9.6 h for females paired with large males (c. 112% of female weight) (P<0.05). Neither frequencies of female nest construction behaviours (digging and probing) nor male courtship behaviour (crossovers and quivers) differed between large- and small-male pairs. Male quivering frequencies were correlated significantly with female digging and probing frequencies, whereas the crossover frequencies were not. It is suggested that delayed spawning by females in the presence of relatively small males is a primary mechanism by which females in the genus Oncorhynchus exhibit mate choice. C1 Natl Marine Fisheries Serv, Resource Enhancement & Utlizat Technol Div, Manchester Res Stn, Manchester, WA 98535 USA. Pacific State Marine Fisheries Commiss, Gladstone, OR 97027 USA. RP Berejikian, BA (reprint author), Natl Marine Fisheries Serv, Resource Enhancement & Utlizat Technol Div, Manchester Res Stn, POB 130, Manchester, WA 98535 USA. NR 41 TC 50 Z9 50 U1 2 U2 12 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-1112 J9 J FISH BIOL JI J. Fish Biol. PD SEP PY 2000 VL 57 IS 3 BP 647 EP 661 DI 10.1111/j.1095-8649.2000.tb00266.x PG 15 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 355UD UT WOS:000089406200008 ER PT J AU Hoke, ME Jahncke, ML Silva, JL Hearnsberger, JO Chamul, RS Suriyaphan, O AF Hoke, ME Jahncke, ML Silva, JL Hearnsberger, JO Chamul, RS Suriyaphan, O TI Stability of washed frozen mince from channel catfish frames SO JOURNAL OF FOOD SCIENCE LA English DT Article DE catfish mince; lipids; frozen storage; rancidity; antioxidants ID STORAGE; SURIMI; HAKE; MACKEREL; LIFE AB Sodium citrate, sodium erythorbate, sodium citrate plus sodium erythorbate, sodium citrate plus sodium erythorbate, and polyphosphate were used in washed and unwashed channel catfish mince. Washing reduced (P less than or equal to 0.05) lipids and increased (P less than or equal to 0.05) Hunter 'L' value (lightness) of mince. Thiobarbituric reactive substances and free fatty-acid changes during frozen storage were reduced in the washed mince. Addition of antioxidants did not significantly improve the overall quality and shelf-life of the frozen mince. Washing did not have an effect on the fatty-acid composition of neutral and phospholipids in the mince. C1 Mississippi State Univ, Mississippi Agr & Forestry Expt Stn, Dept Food Sci & Technol, Mississippi State, MS 39762 USA. Natl Marine Fisheries Serv, Natl Seafood Inspect Lab, Pascagoula, MS USA. RP Silva, JL (reprint author), Mississippi State Univ, Mississippi Agr & Forestry Expt Stn, Dept Food Sci & Technol, Mississippi State, MS 39762 USA. NR 45 TC 16 Z9 16 U1 0 U2 0 PU INST FOOD TECHNOLOGISTS PI CHICAGO PA SUITE 300 221 N LASALLE ST, CHICAGO, IL 60601-1291 USA SN 0022-1147 J9 J FOOD SCI JI J. Food Sci. PD SEP PY 2000 VL 65 IS 6 BP 1083 EP 1086 DI 10.1111/j.1365-2621.2000.tb09422.x PG 4 WC Food Science & Technology SC Food Science & Technology GA 370NR UT WOS:000165129600030 ER PT J AU Ostgaard, N Stadsnes, J Bjordal, J Vondrak, RR Cummer, SA Chenette, DL Schulz, M Pronko, JG AF Ostgaard, N Stadsnes, J Bjordal, J Vondrak, RR Cummer, SA Chenette, DL Schulz, M Pronko, JG TI Cause of the localized maximum of X-ray emission in the morning sector: A comparison with electron measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID AURORAL-ZONE; PRECIPITATION AB The Polar Ionospheric X-ray Imaging Experiment (PIXIE) on board the Polar satellite has provided the first global scale views of the patterns of electron precipitation through imaging of the atmospheric X-ray bremsstrahlung. While other remote sensing techniques like ultraviolet (UV) and visible imaging sense emissions that are dominantly produced by low-energy electrons (<10 keV), the PIXIE X-ray images used in this study respond to electrons of energy above -3 keV. From a statistical study of global X-ray emission a localized maximum in the morning sector, delayed with respect to substorm onset, is found to be a common feature during substorms. The time delay of this morning precipitation relative to substorm onset strongly indicates that this localized maximum is caused by electrons injected in the midnight sector drifting into a region in the dawnside magnetosphere where some mechanism effectively scatters the electrons into the loss cone. In this study we have examined two isolated substorms that occurred on July 31, 1997, and September 4, 1997, to investigate these features in more detail. PIXIE images are used to examine the global structures of the two events. Particle measurements from several low-altitude satellites, NOAA and DMSP, have provided fine structure information of the spatial and spectral development of the morning precipitation. We find good spatial correlation between X-ray emission and electron measurements for both these events. Comparison of measured electron spectra and electron spectra derived from X-ray measurements by PIXIE are also presented and correlates fairly well. The technique for deriving electron characteristics from the X-ray measurements are described and discussed. We find that both the electron spectra and the X-ray spectra can be represented by double or single exponentials. The electron spectra measured in the early stage of the localized morning maximum of X-ray emission strongly indicate that the scattering of >2 - 10 keV electrons by wave-particle interaction into the loss cone is the main mechanism for this precipitation. C1 Univ Bergen, Dept Phys, N-5007 Bergen, Norway. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. Univ Nevada, Dept Phys, Reno, NV 89507 USA. RP Ostgaard, N (reprint author), Univ Oslo, Dept Phys, POB 1048, N-0316 Oslo, Norway. RI Cummer, Steven/A-6118-2008 OI Cummer, Steven/0000-0002-0002-0613 NR 32 TC 22 Z9 22 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 SEP 1 PY 2000 VL 105 IS A9 BP 20869 EP 20883 DI 10.1029/1999JA000354 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356GU UT WOS:000089436200003 ER PT J AU Neugebauer, M Cravens, TE Lisse, CM Ipavich, FM Christian, D von Steiger, R Bochsler, P Shah, PD Armstrong, TP AF Neugebauer, M Cravens, TE Lisse, CM Ipavich, FM Christian, D von Steiger, R Bochsler, P Shah, PD Armstrong, TP TI The relation of temporal variations of soft X-ray emission from comet Hyakutake to variations of ion fluxes in the solar wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EXTREME-ULTRAVIOLET EMISSION; HALE-BOPP; C/1996 B2; SOHO; CHARGE; O1 AB Both the Rontgen X-Ray Satellite (ROSAT) and the Extreme Ultraviolet Explorer (EUVE) have detected soft X-ray emission from comet C/Hyakutake 1996 B2. This emission varied by a factor of about 2 over a few hours and by a factor of 4 from day to day. One explanation for the excitation of cometary X rays is the charge transfer mechanism suggested by Cravens. This process involves charge exchange collisions between highly charged heavy ions in the solar wind and neutral gas in the cometary coma. Oxygen ion fluxes observed by the Charge, Element, and Isotope Analysis System (CELIAS) Mass Time-of-Flight (MTOF) instrument on the SOHO spacecraft and proton fluxes measured by near-Earth spacecraft are mapped to the location of the comet to demonstrate that the comet X-ray variability can be explained on the basis of variability in the solar wind. There is a good correlation between cometary X-ray emission and oxygen ion fluxes and a poorer correlation with proton flux. The correlation between the solar wind oxygen flux and cometary X rays degrades with increasing latitudinal separation of SOHO from the comet. Cometary X-ray emission is not sensitive to variations in solar X-ray fluxes and is unlikely to be caused by crossing of the heliospheric current sheet. The charge transfer mechanism appears to be supported by all the data examined to date. Cometary X rays have some shortcomings as remote sensors of the solar wind, however, because of variations in cometary gas production rates and in the charge states and abundances of heavy solar wind ions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Maryland, Dept Phys, College Pk, MD 20742 USA. Univ Bern, Inst Phys, CH-3012 Bern, Switzerland. Int Space Sci Inst, CH-3012 Bern, Switzerland. RP Neugebauer, M (reprint author), CALTECH, Jet Prop Lab, MS 169-506,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Von Steiger, Rudolf/F-6822-2011; Lisse, Carey/B-7772-2016 OI Von Steiger, Rudolf/0000-0002-3350-0023; Lisse, Carey/0000-0002-9548-1526 NR 29 TC 32 Z9 32 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 SEP 1 PY 2000 VL 105 IS A9 BP 20949 EP 20955 DI 10.1029/1999JA000299 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356GU UT WOS:000089436200009 ER PT J AU Hull, AJ Scudder, JD Fitzenreiter, RJ Ogilvie, KW Newbury, JA Russell, CT AF Hull, AJ Scudder, JD Fitzenreiter, RJ Ogilvie, KW Newbury, JA Russell, CT TI Electron temperature and de Hoffmann-Teller potential change across the Earth's bow shock: New results from ISEE 1 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; VELOCITY DISTRIBUTIONS; COLLISIONLESS SHOCKS; RESOLVED LAYER; HIGH-BETA; PLASMA; FIELD; WAVE AB We present a survey of the trends between the electron temperature increase Delta T-e, and the de Hoffmann-Teller frame (HTF) electrostatic potential jump Delta Phi(HT) and their correlation with other parameters that characterize the shock transition using a new ISEE 1 database of 129 Earth bow shock crossings. A fundamental understanding of the HTF potential is central to distinguishing the reversible and irreversible changes to electron temperature across collisionless shocks. The HTF potential is estimated using three different techniques: (1) integrating the steady state, electron fluid momentum equation across the shock layer using high time resolution plasma and field data from LSEE 1, (2) using the steady state, electron fluid energy equation, and (3) using an electron polytrope approximation. We find that Delta Phi(HT) and Delta T-e are strongly and positively correlated with \Delta(m(p)U(n)(2)/2)\, which is in good qualitative agreement with earlier experimental surveys [Thomsen et al., 1987b; Schwartz et al., 1988] that used bow shock model normals and used the flow in the spacecraft frame. There is a strong linear organization of the Delta T-e with Delta Phi(HT), which suggests an average effective electron polytropic index of [gamma(e)] approximate to 2. In addition, Delta T-e and Delta Phi(HT) are organized by beta(e), although our results may be biased by our limited sampling of shock conditions. Comparisons indicate that the differentials in the HTF potential delta Phi(HT) are proportional to the differentials in the magnetic field intensity delta B across the shock, with a proportionality constant kappa that is a fixed constant for a given shock crossing. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. RP Hull, AJ (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RI Scudder, Jack/D-8417-2013 OI Scudder, Jack/0000-0001-7975-5630 NR 28 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 SEP 1 PY 2000 VL 105 IS A9 BP 20957 EP 20971 DI 10.1029/2000JA900049 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356GU UT WOS:000089436200010 ER PT J AU McDonald, FB Burlaga, LF McGuire, RE Ness, NF AF McDonald, FB Burlaga, LF McGuire, RE Ness, NF TI The onset of long-term cosmic ray modulation in cycle 23 coupled with a transient increase of anomalous cosmic rays in the distant heliosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MERGED INTERACTION REGIONS; OUTER HELIOSPHERE; FORBUSH DECREASE; TRANSPORT; DIFFUSION; INTENSITY; DRIFT; MODEL AB The onset of significant solar activity in cycle 23 began in November 1997 with several modest events and was followed by an enhanced period of solar activity in April and May 1998. This latter series of events produced a well-defined step decrease in the cosmic ray intensity at 1 AU as observed by the Goddard Cosmic Ray Experiment on IMP 8. Over the ensuing 2 years there are further decreases in the IMP 8 data with the cumulative effect being in good agreement with the net decrease in cycle 21 at a similar time in the solar cycle. At Voyager 1 (72 AU, 34 degrees N) and Voyager 2 (56 AU, 24 degrees S) there are transient increases in the intensity of 1.8-2.8 MeV H that mark the passage of a large interplanetary disturbance around 1998.75 that was most probably associated with the April-May activity. However, there was no durable decrease observed at that time in the galactic or anomalous cosmic rays. What is unique about this event at Voyager 2 (V 2) in the outer heliosphere is the precursor increase in the anomalous cosmic ray intensity associated with this interplanetary disturbance as defined by the V 2 magnetic field observations. This enhancement event establishes that reacceleration of anomalous cosmic rays can occur in the outer heliosphere. The onset of durable modulation at V 2 begins around 1999.5, probably in association with the disturbances that produced the second step-like decrease at 1 AU. At Voyager 1 there is preliminary evidence that the corresponding onset time is 1999.5. C1 Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. RP McDonald, FB (reprint author), Univ Maryland, Inst Phys Sci & Technol, 3245 Comp & Space Sci Bldg, College Pk, MD 20742 USA. NR 22 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 SEP 1 PY 2000 VL 105 IS A9 BP 20997 EP 21003 DI 10.1029/2000JA000072 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356GU UT WOS:000089436200013 ER PT J AU Strangeway, RJ Russell, CT Carlson, CW McFadden, JP Ergun, RE Temerin, M Klumpar, DM Peterson, WK Moore, TE AF Strangeway, RJ Russell, CT Carlson, CW McFadden, JP Ergun, RE Temerin, M Klumpar, DM Peterson, WK Moore, TE TI Cusp field-aligned currents and ion outflows SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID IONOSPHERIC MASS EJECTION; ACCELERATION; IMF AB On September 24 and 25, 1998, the Polar spacecraft observed intense outflows of terrestrial ions in association with the passage of an interplanetary shock and coronal mass ejection. The orbit of the Fast Auroral Snapshot (FAST) Explorer was in the noon-midnight meridian during this ion outflow event, and FAST passed through the dayside cusp region at similar to 4000 km altitude every 2.2 hours. FAST was therefore able to monitor the ion outflows subsequently observed by Polar. We show that while the outflows were more intense after the shock passage, the overall particle and field signatures within the cusp region were qualitatively similar both before and after the shock passage. FAST observations show that the cusp particle precipitation marks the lower-latitude leg of a pair of field-aligned currents and further, that both field-aligned current sheets appear to be on open field lines. Moreover, the polarity of the cusp currents is controlled by the polarity of the interplanetary magnetic field (IMF) y-component, such that the magnetic field perturbation associated with the pair of cusp currents is in the same direction as the IMF B-y. This is a consequence of the reconnection of cusp-region field lines at the magnetopause, with the flux transport resulting in electromagnetic energy being transmitted along field lines to the ionosphere as Poynting flux. We show that this Poynting flux can be as high as 120 mW m(-2) (120 ergs cm(-2) s(-1)) at FAST altitudes (similar to 500 mW m(-2) at ionospheric altitudes), presumably because of the strong IMF B-y (similar to 40 nT), and is the dominant energy input to the cusp-region ionosphere. Furthermore, we find that the peak ion outflow flux is correlated with the peak downward Poynting flux, although only a few passes through the cusp centered around the time of the shock passage were used to determine this correlation. The energy carried by Poynting flux is dissipated as heat within the ionosphere, through Joule dissipation. The heating will tend to increase the ionospheric scale height, allowing greater access of ionospheric ions to the altitudes where transverse ion heating via ELF waves can occur. Thus electromagnetic energy supplied by the transport of reconnected magnetic flux is the essential first step in a multistep process that enhances the outflow of ionospheric plasma in the dayside cusp. C1 Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Strangeway, RJ (reprint author), Univ Calif Los Angeles, Inst Geophys & Planetary Phys, 405 Hilgard Ave, Los Angeles, CA 90095 USA. RI Moore, Thomas/D-4675-2012; Peterson, WK/A-8706-2009 OI Moore, Thomas/0000-0002-3150-1137; Peterson, WK/0000-0002-1513-6096 NR 19 TC 51 Z9 51 U1 2 U2 4 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 SEP 1 PY 2000 VL 105 IS A9 BP 21129 EP 21142 DI 10.1029/2000JA900032 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356GU UT WOS:000089436200026 ER PT J AU Fairfield, DH Otto, A Mukai, T Kokubun, S Lepping, RP Steinberg, JT Lazarus, AJ Yamamoto, T AF Fairfield, DH Otto, A Mukai, T Kokubun, S Lepping, RP Steinberg, JT Lazarus, AJ Yamamoto, T TI Geotail observations of the Kelvin-Helmholtz instability at the equatorial magnetotail boundary for parallel northward fields SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID NEAR-EARTH MAGNETOTAIL; INTERPLANETARY MAGNETIC-FIELD; AURORAL BRIGHT SPOTS; MAGNETOSPHERIC BOUNDARY; PLASMA VORTICES; MAGNETOPAUSE; LAYER; SURFACE; DAYSIDE; FLANKS AB For several hours on March 24, 1995, the Geotail spacecraft remained near the duskside magnetotail boundary some 15 R-E behind the Earth while the solar wind remained very quiet (V=330 km s(-1), n=14-21 cm(-3)) with a very steady 11-nT northward magnetic field. Geotail experienced multiple crossings of a boundary between a dense (n=19 cm(-3)), cool (T-p=40 eV), rapidly flowing (V=310 km s(-1)) magnetosheath plasma and an interior region characterized by slower tailward velocities (V=100 km s(-1)), lower but substantial densities (n=3 cm(-3)) and somewhat hotter ions (220 eV). The crossings recurred with a roughly 3-min periodicity, and all quantities were highly variable in the boundary region. The magnetic field, in fact, exhibited some of the largest fluctuations seen anywhere in space, despite the fact that the exterior magnetosheath field and the interior magnetosphere field were both very northward and nearly parallel. On the basis of an MHD simulation of this event, we argue that the multiple crossings are due to a Kelvin-Helmholtz instability at the boundary that generates vortices which move past the spacecraft. A determination of boundary normals supports Kelvin-Helmholtz theory in that the nonlinear steepening of the waves is seen on the leading edge of the waves rather than on the trailing edge, as has sometimes been seen in the past. It is concluded that the Kelvin-Helmholtz instability is an important process for transferring energy, momentum and particles to the magnetotail during times of very northward interplanetary magnetic field. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Nagoya Univ, STELAB, Toyokawa 442, Japan. MIT, Space Res Ctr, Cambridge, MA 02139 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. RP Fairfield, DH (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Code 695, Greenbelt, MD 20771 USA. NR 35 TC 166 Z9 169 U1 2 U2 16 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 SEP 1 PY 2000 VL 105 IS A9 BP 21159 EP 21173 DI 10.1029/1999JA000316 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356GU UT WOS:000089436200028 ER PT J AU Otto, A Fairfield, DH AF Otto, A Fairfield, DH TI Kelvin-Helmholtz instability at the magnetotail boundary: MHD simulation and comparison with Geotail observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID NEAR-EARTH MAGNETOTAIL; MAGNETIC-FLUX TRANSFER; MAGNETOSPHERIC BOUNDARY; MAGNETOPAUSE-BOUNDARY; DAYSIDE MAGNETOPAUSE; SELF-ORGANIZATION; PLASMA SHEET; SOLAR-WIND; RECONNECTION; FIELD AB On March 24, 1995, the Geotail spacecraft observed large fluctuations of the magnetic field and plasma propel-ties in the low-latitude boundary layer about 15 R-E tailward of the dusk meridian. Although the magnetospheric and magnetosheath magnetic fields were strongly northward, the B-Z component showed strong short-duration fluctuations in which B-z could even reach negative values. We have used two-dimensional magnetohydrodynamic simulations with magnetospheric and magnetosheath input parameters specifically chosen for this Geotail event to identify the processes which cause the observed boundary properties. It is shown that these fluctuations can be explained by the Kelvin-Helmholtz instability if the k vector of the instability has a component along the magnetic field direction. The simulation results show many of the characteristic properties of the Geotail observations. In particular, the quasi-periodic strong fluctuations are well explained by satellite crossings through the Kelvin-Helmholtz vortices. It is illustrated how the interior structure of the Kelvin-Helmholtz vortices leads to the rapid fluctuations in the Geotail observations. Our results suggest an average Kelvin-Helmholtz wavelength of about 5 R-E, with a vortex size of close to 2 R-E for an average repetition time of 2.5 min. The growth time for these waves implies a source region of about 10-16 R-E upstream from the location of the Geotail spacecraft (i.e., near the dusk meridian). The results also indicate a considerable mass transport of magnetosheath material into the magnetosphere by magnetic reconnection in the Kelvin-Helmholtz vortices. C1 Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Otto, A (reprint author), Univ Alaska Fairbanks, Inst Geophys, Fairbanks, AK 99775 USA. NR 40 TC 171 Z9 172 U1 3 U2 10 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 SEP 1 PY 2000 VL 105 IS A9 BP 21175 EP 21190 DI 10.1029/1999JA000312 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356GU UT WOS:000089436200029 ER PT J AU Morelli, EA AF Morelli, EA TI Real-time parameter estimation in the frequency domain SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB A method for real-time estimation of parameters in a linear dynamic state-space model was developed and studied. The application is aircraft dynamic model parameter Estimation from measured data in Right. Equation error in the frequency domain was used with a recursive Fourier transform for the real-time data analysis. Linear and nonlinear simulation examples and flight test data from the F-18 High Alpha Research Vehicle. were used to demonstrate that the technique produces accurate model parameter estimates with appropriate error bounds. Parameter estimates converged in less than 1 cycle of the dominant dynamic mode, using no a priori information, with control surface inputs measured in flight during ordinary piloted maneuvers. The real-time parameter estimation method has low computational requirements and could be implemented aboard an aircraft in real time. C1 NASA, Langley Res Ctr, Dynam & Control Branch, Hampton, VA 23681 USA. RP Morelli, EA (reprint author), NASA, Langley Res Ctr, Dynam & Control Branch, Hampton, VA 23681 USA. NR 16 TC 34 Z9 38 U1 0 U2 7 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 SEP-OCT PY 2000 VL 23 IS 5 BP 812 EP 818 DI 10.2514/2.4642 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 354ZW UT WOS:000089362000007 ER PT J AU Farley, TC Hansman, RJ Amonlirdviman, K Endsley, MR AF Farley, TC Hansman, RJ Amonlirdviman, K Endsley, MR TI Shared information between pilots and controllers in tactical air traffic control SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Air-ground datalink systems are being developed to enable pilots and air traffic controllers to share Information more fully. The sharing of information is generally expected to enhance their shared situation awareness and foster more collaborative decision making. An exploratory, part-task simulator experiment is described that evaluates the extent to which shared information may lead pilots and controllers to cooperate or compete when negotiating route amendments. The results indicate an improvement in situation awareness for pilots and controllers and a willingness to work cooperatively. independent of datalink considerations, the experiment also demonstrates the value of providing controllers with a good-quality weather representation on their plan view displays. Observed improvements in situation awareness and separation assurance are discussed. C1 MIT, Int Ctr Air Transportat, Cambridge, MA 02139 USA. SA Technol, Marietta, GA 30066 USA. RP Farley, TC (reprint author), NASA, Ames Res Ctr, Terminal Area Air Traffic Management Res Branch, M-S 210-6, Moffett Field, CA 94035 USA. NR 13 TC 4 Z9 4 U1 0 U2 2 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 SEP-OCT PY 2000 VL 23 IS 5 BP 826 EP 836 DI 10.2514/2.4644 PG 11 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 354ZW UT WOS:000089362000009 ER PT J AU Clark, RL Cox, DE AF Clark, RL Cox, DE TI Multi-input, multi-output, band-limited transducer selection for disturbance rejection SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SENSOR PLACEMENT; FLEXIBLE STRUCTURES; ACTUATOR C1 Duke Univ, Dept Mech Engn & Mat Sci, Durham, NC 27708 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Clark, RL (reprint author), Duke Univ, Dept Mech Engn & Mat Sci, Box 90300, Durham, NC 27708 USA. NR 10 TC 2 Z9 2 U1 0 U2 1 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 SEP-OCT PY 2000 VL 23 IS 5 BP 903 EP 906 DI 10.2514/2.4626 PG 4 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 354ZW UT WOS:000089362000023 ER PT J AU Scott, RC Hoadley, ST Wieseman, CD Durham, MH AF Scott, RC Hoadley, ST Wieseman, CD Durham, MH TI Benchmark active controls technology model aerodynamic data SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT 35th Aerospace Science Meeting CY JAN 06-10, 1997 CL RENO, NEVADA SP Aerosp Sci AB The benchmark active controls technology (BACT) model is a part of the Benchmark Models Program (BMP). The BMP is a NASA Langley Research Center program that includes a series of models that were used to study different aeroelastic phenomena and to validate computational fluid dynamics (CFD) codes. The primary objective of BACT testing was to obtain steady and unsteady loads, accelerations, and aerodynamic pressures due to control surface activity to calibrate unsteady CFD codes and validate active control design tools. Three wind-tunnel tests in the Transonic Dynamics Tunnel have been completed. The first and parts of the second and third tests focused on collecting open-loop data to define the model's aeroservoelastic characteristics, including the flutter boundary across the Mach range; these data are presented. An extensive database of over 3000 data sets was obtained. This database includes steady and unsteady control surface effectiveness data, including pressure distributions, and overall model loads due to deflections of a trailing-edge control surface and upper and lower surface spoilers. C1 NASA, Langley Res Ctr, Aeroelastic Branch, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Data Acquisit & Informat Management Branch, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Subson Transportat Off, Hampton, VA 23681 USA. RP Scott, RC (reprint author), NASA, Langley Res Ctr, Aeroelastic Branch, Hampton, VA 23681 USA. NR 9 TC 28 Z9 29 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 SEP-OCT PY 2000 VL 23 IS 5 BP 914 EP 921 DI 10.2514/2.4632 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 354ZW UT WOS:000089362000029 ER PT J AU Bennett, RM Scott, RC Wieseman, CD AF Bennett, RM Scott, RC Wieseman, CD TI Computational test cases for the benchmark active controls model SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Unsteady aerodynamic and aeroelastic computational test cases have been selected from the data set for the Benchmark Active Controls Technology model. Data sets for trailing-edge control surface oscillations and upper-surface spoiler oscillations for a range of Mach numbers, angle of attack, and static control deflections are included. Cases also include static angles of attack, static trailing-edge control, and static upper-surface spoiler deflections for a range of conditions near those for the oscillation cases. The aeroelastic test casts include three types of flutter instability and dynamic response measurements for oscillations of the controls on the flexible mount. C1 NASA, Langley Res Ctr, Aeroelastic Branch, Hampton, VA 23681 USA. RP Bennett, RM (reprint author), NASA, Langley Res Ctr, Aeroelastic Branch, Mail Stop 340, Hampton, VA 23681 USA. NR 39 TC 16 Z9 16 U1 0 U2 3 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 SEP-OCT PY 2000 VL 23 IS 5 BP 922 EP 929 DI 10.2514/2.4634 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 354ZW UT WOS:000089362000030 ER PT J AU Mukhopadhyay, V AF Mukhopadhyay, V TI Transonic flutter suppression control law design and wind-tunnel test results SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT AIAA/ASME/ASCE/AHS/ASC 40th Structures, Structural Dynamics, and Materials Conference CY APR 12-15, 1999 CL ST LOUIS, MISSOURI SP Amer Inst Aeronaut & Astronaut, ASME, ASCE, AHS, ASC AB Flutter suppression control law design and wind-tunnel test results in transonic flow for a NACA 0012 wing model, under the benchmark active control technology program at NASA Langley Research Center, will be presented. Two control law design processes using classical and minimax techniques are described. Design considerations fur improving the multivariable system robustness are outlined. The classical control law was digitally implemented and tested in the NASA Langley Transonic Dynamics Tunnel. In wind-tunnel tests in air and heavy gas medium, the closed-loop Butter dynamic pressure was increased by over 50% up to the wind-tunnel upper limit. The active Butter suppression system also provided significant robustness, relative to gain and phase perturbations, even in the presence of transonic shocks and Row separation. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Mukhopadhyay, V (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 17 TC 50 Z9 52 U1 0 U2 9 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 SEP-OCT PY 2000 VL 23 IS 5 BP 930 EP 937 DI 10.2514/2.4635 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 354ZW UT WOS:000089362000031 ER PT J AU Kelkar, AG Joshi, SM AF Kelkar, AG Joshi, SM TI Passivity-based robust control with application to benchmark active controls technology wing SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SYSTEMS AB A passivity-based robust control design methodology is presented. A brief review of the stability results is given for passive linear and nonlinear systems followed by four different passification methods for rendering nonpassive systems passive. The robust control methodology via robust passification is demonstrated by application to the Benchmark Active Controls Technology subsonic wing. The controller design is shown to provide robust stability and satisfactory performance. C1 Kansas State Univ, Manhattan, KS 66506 USA. NASA, Langley Res Ctr, Hampton, VA 23666 USA. RP Kelkar, AG (reprint author), Kansas State Univ, Manhattan, KS 66506 USA. NR 20 TC 33 Z9 33 U1 0 U2 2 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 SEP-OCT PY 2000 VL 23 IS 5 BP 938 EP 947 DI 10.2514/2.4636 PG 10 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 354ZW UT WOS:000089362000032 ER PT J AU Subramanian, A Mu, H Kadambi, JR Wernet, MP Brendzel, AM Harasaki, H AF Subramanian, A Mu, H Kadambi, JR Wernet, MP Brendzel, AM Harasaki, H TI Particle image velocimetry investigation of intra-valvular flow fields of a bileaflet mechanical heart valve in a pulsatile flow SO JOURNAL OF HEART VALVE DISEASE LA English DT Article ID SHEAR-STRESS; PROSTHESIS; PRESSURE; GRADIENTS; VELOCITY; INVITRO; DOPPLER C1 Case Western Reserve Univ, Dept Mech & Aerosp Engn, Cleveland, OH 44106 USA. NASA, Glenn Res Ctr, Cleveland, OH USA. St Jude Med Inc, St Paul, MN USA. Cleveland Clin Fdn, Dept Biomed Engn, Cleveland, OH 44195 USA. RP Kadambi, JR (reprint author), Case Western Reserve Univ, Dept Mech & Aerosp Engn, 10900 Euclid Ave, Cleveland, OH 44106 USA. NR 32 TC 24 Z9 24 U1 0 U2 2 PU I C R PUBLISHERS PI NORTHWOOD PA CRISPIN HOUSE, 12/A SOUTH APPROACH, MOOR PARK, NORTHWOOD, ENGLAND HA6 2ET SN 0966-8519 J9 J HEART VALVE DIS JI J. Heart Valve Dis. PD SEP PY 2000 VL 9 IS 5 BP 721 EP 731 PG 11 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA 358MB UT WOS:000089560900021 PM 11041190 ER PT J AU Leong, MY Samuelsen, GS Holdeman, JD AF Leong, MY Samuelsen, GS Holdeman, JD TI Optimization of jet mixing into a rich, reacting crossflow SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID MULTIPLE JETS; CYLINDRICAL DUCT; FLOW; COMBUSTOR AB Radial jet mixing of pure air into a fuel-rich, reacting crossflow confined to a cylindrical geometry is addressed with a focus on establishing an optimal number of jet orifices. Note that the optimum would not be expected to be universal. That is, the optimum mixer that one would identify will depend on both the momentum-flux ratio and an axial distance appropriate to the application, The number of round holes that most efficiently mixes the jets with the mainstream flow, and thereby minimizes the residence time of near-stoichiometric and unreacted packets, was determined. Such a condition might reduce pollutant formation in axially staged, gas turbine combustor systems. Five different configurations consisting of 8, 10, 12, 14, and 18 round holes are reported. An optimum number of jet orifices is found for a jet to mainstream momentum-flux ratio J of 57 and a mass-flow ratio (MR) of 2.5. For this condition, the 14-orifice? rest! produces the lowest spatial unmixedness and the most uniformly distributed species concentration and temperature profiles at a plane located an axial distance equal to one duct diameter from the jet orifice inlet. Note that this is the same configuration that would be identified from non-reacting experiments. C1 Univ Calif Irvine, Irvine, CA 92697 USA. NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. RP Leong, MY (reprint author), Univ Calif Irvine, Irvine, CA 92697 USA. NR 28 TC 14 Z9 14 U1 1 U2 3 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 SEP-OCT PY 2000 VL 16 IS 5 BP 729 EP 735 DI 10.2514/2.5643 PG 7 WC Engineering, Aerospace SC Engineering GA 354NC UT WOS:000089335700001 ER PT J AU Nallasamy, M Sutliff, DL Heidelberg, LJ AF Nallasamy, M Sutliff, DL Heidelberg, LJ TI Propagation of spinning acoustic modes in turbofan exhaust ducts SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA 37th Aerospace Sciences Meeting and Exhibit CY JAN 11-14, 1999 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut AB A theoretical and experimental study of sound propagation in a turbofan exhaust duct is presented. The effect of duct-area change on the propagation of rotor-stater interaction tones is studied. The pressure reflection coefficient and far-field directivity shape variations as a result of duct termination, duct-flow Mach number, and exhaust hub-to-tip radius ratio are examined, A finite element method and a modal analysis technique that is employed in induct mode measurements are used. The computational results show that even with large changes in duct area there is no transfer of modal power from one mode to another, as it propagates through varying cross-sectional area. However, as the exhaust hub-to-tip radius ratio increases, higher-order radial modes get cut off. Exponential horn termination keeps the principal lobe peak angle fixed for the first-order radial modes at the design speed, Increases in flow Mach number and exhaust hub-to-tip radius ratio move the principal lobe peak angle away from the exhaust duct axis. This reduces the axial beaming of acoustic energy of low-order spinning modes and enhances absorption by acoustic liners. The computed axial variation of acoustic power in the duct and phase angle of acoustic pressure show good agreement with the experimental data. C1 DYNACS Engn Co, Brook Pk, OH 44142 USA. AYT Corp, Cleveland, OH 44135 USA. NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. RP Nallasamy, M (reprint author), DYNACS Engn Co, Brook Pk, OH 44142 USA. NR 11 TC 4 Z9 4 U1 0 U2 0 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 SEP-OCT PY 2000 VL 16 IS 5 BP 736 EP 743 DI 10.2514/2.5654 PG 8 WC Engineering, Aerospace SC Engineering GA 354NC UT WOS:000089335700002 ER PT J AU Hudson, ST Coleman, HW AF Hudson, ST Coleman, HW TI Analytical and experimental assessment of two methods of determining turbine efficiency SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA 20th Advanced Measurement and Ground Testing Technology Conference CY JUN 15-18, 1998 CL ALBUQUERQUE, NEW MEXICO SP Amer Inst Aeronaut & Astronaut AB The efficiency of a turbine may be calculated from measured test variables by several different methods. However, the literature does not contain documentation to aid one in determining the preferred efficiency method for particular test situations. Two methods commonly used for cold airflow testing of turbines, the thermodynamic and the mechanical methods, were evaluated both experimentally and using uncertainty analysis techniques. The experimental work involved performance testing of a next-generation, compact, high-turning-angle turbine design in which the flow contained significant high-gradient regions. The turbine efficiency was calculated from the measured test data using both efficiency methods, and enhanced uncertainty analysis tools were developed to evaluate the efficiency uncertainty for each method. The efficiency uncertainty equations were written in a new form to account properly for conceptual bias and correlated bias terms, The results showed that using the form of the equations developed was essential to obtaining the correct efficiency uncertainty estimates. The efficiency uncertainty estimates obtained from the analysis then allowed a comparison of the two methods from which conclusions were drawn to guide in determining the preferred efficiency method for individual applications. C1 NASA, George C Marshall Space Flight Ctr, Space Transportat Directorate, Huntsville, AL 35812 USA. Univ Alabama, Dept Mech & Aerosp Engn, Prop Res Ctr, Huntsville, AL 35899 USA. RP Hudson, ST (reprint author), NASA, George C Marshall Space Flight Ctr, Space Transportat Directorate, TD63, Huntsville, AL 35812 USA. NR 20 TC 4 Z9 4 U1 2 U2 3 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 SEP-OCT PY 2000 VL 16 IS 5 BP 760 EP 767 DI 10.2514/2.5664 PG 8 WC Engineering, Aerospace SC Engineering GA 354NC UT WOS:000089335700005 ER PT J AU Greendyke, RB Paxson, DE Schobeiri, MT AF Greendyke, RB Paxson, DE Schobeiri, MT TI Dynamic simulation of a wave-rotor-topped turboshaft engine SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/ASME/SAE/ASEE 33rd Joint Propulsion Conference CY JUL 06-09, 1997 CL SEATTLE, WASHINGTON SP Amer Inst Aeronaut & Astronaut, ASME, SAE, ASEE AB The dynamic behavior of a wave-rotor-topped turboshaft engine is examined using a numerical simulation. The simulation utilizes an explicit, one-dimensional, multipassage, computational fluid dynamics- (CFD-) based wave-rotor code in combination with an implicit, one-dimensional, component-level dynamic engine simulation code. Transient responses to rapid fuel flow rate changes and compressor inlet pressure! changes are simulated and compared with those of a similarly sized, untopped, turboshaft engine. Results indicate that the wave-rotor-topped engine responds in a stable and rapid manner. Furthermore, during certain transient operations, the wave rotor actually tends to enhance engine stability. In particular, there is no tendency toward surge in the compressor of the wave-rotor-topped engine during rapid acceleration. In fact, the compressor actually moves slightly away from the surge line during this transient. This behavior is precisely the opposite to that of an untopped engine. The simulation is described. Issues associated with integrating CFD and component-level codes are discussed. Results from several transient simulations are presented and discussed. C1 Univ Texas, Dept Engn Mech, Tyler, TX 75799 USA. NASA, John H Glenn Res Ctr, Controls & Dynam Technol Branch, Cleveland, OH 44135 USA. Texas A&M Univ, Dept Engn Mech, College Stn, TX 77845 USA. RP Greendyke, RB (reprint author), Univ Texas, Dept Engn Mech, Tyler, TX 75799 USA. NR 12 TC 2 Z9 2 U1 0 U2 1 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 SEP-OCT PY 2000 VL 16 IS 5 BP 792 EP 796 DI 10.2514/2.5668 PG 5 WC Engineering, Aerospace SC Engineering GA 354NC UT WOS:000089335700009 ER PT J AU Schmidt, GR Gerrish, HP Martin, JJ Smith, GA Meyer, KJ AF Schmidt, GR Gerrish, HP Martin, JJ Smith, GA Meyer, KJ TI Antimatter requirements and energy costs for near-term propulsion applications SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID CURSOR INTERSTELLAR MISSIONS; INITIATED MICROFUSION; ANTIPROTONS; AIMSTAR AB The superior energy density of antimatter annihilation has often been pointed to as the ultimate source of energy for propulsion. However, the limited capacity and very low efficiency of present-day antiproton production methods suggest that antimatter may be too costly to consider for near-term propulsion applications. We address this issue by assessing the antimatter requirements fur six different types of propulsion concepts, including two in which antiprotons are used to drive energy release from combined fission/fusion, These requirements art: compared against the capacity of both the current antimatter production infrastructure and the improved capabilities that could exist within the early part of next century. Results show that although it may be impractical to consider systems that rely on antimatter as the sole source of propulsive energy, the requirements for propulsion based on antimatter-assisted fission/fusion do fall within projected near-term production capabilities, In fact, a new facility designed solely for antiproton production but based on existing technology could feasibly support interstellar precursor missions and omniplanetary spaceflight with antimatter costs ranging up to $6.4 x 10(6) per mission. C1 NASA, George C Marshall Space Flight Ctr, Prop Res Ctr, Huntsville, AL 35812 USA. Penn State Univ, Elementary Particle Sci Lab, University Pk, PA 16802 USA. Penn State Univ, Dept Aerosp Engn, University Pk, PA 16802 USA. RP Schmidt, GR (reprint author), NASA, George C Marshall Space Flight Ctr, Prop Res Ctr, Huntsville, AL 35812 USA. NR 26 TC 9 Z9 9 U1 4 U2 5 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 SEP-OCT PY 2000 VL 16 IS 5 BP 923 EP 928 DI 10.2514/2.5661 PG 6 WC Engineering, Aerospace SC Engineering GA 354NC UT WOS:000089335700026 ER PT J AU Goldman, A Gamache, RR Perrin, A Flaud, JM Rinsland, CP Rothman, LS AF Goldman, A Gamache, RR Perrin, A Flaud, JM Rinsland, CP Rothman, LS TI HITRAN partition functions and weighted transition-moments squared SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Review ID FAR-INFRARED-SPECTRUM; FOURIER-TRANSFORM SPECTROSCOPY; HIGH-RESOLUTION SPECTROSCOPY; SUBMILLIMETER-WAVE SPECTRUM; ABSOLUTE LINE-INTENSITIES; CHLORINE NITRATE; GROUND-STATE; ROTATIONAL SPECTRUM; TORSIONAL SPECTRUM; NU-3 BANDS AB The calculations of the partition functions and weighted transition-moments squared in the HITRAN database are reviewed. It was found that for several of the HITRAN molecules corrections are needed to the partition functions. Corrections to the weighted transition-moments squared are needed for most of the HITRAN molecules. Replacement of the weighted transition-moments squared by other quantities is proposed. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Denver, Dept Phys, Denver, CO 80208 USA. Univ Massachusetts, Dept Environm Earth & Atmospher Sci, Lowell, MA 01854 USA. Univ Paris Sud, Photophys Mol Lab, F-91405 Orsay, France. NASA, Div Atmospher Sci, Langley Res Ctr, Hampton, VA 23681 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Goldman, A (reprint author), Univ Denver, Dept Phys, Denver, CO 80208 USA. OI Rothman, Laurence/0000-0002-3837-4847 NR 111 TC 41 Z9 42 U1 2 U2 16 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD SEP 1 PY 2000 VL 66 IS 5 BP 455 EP 486 DI 10.1016/S0022-4073(99)00176-4 PG 32 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 318KD UT WOS:000087282300003 ER PT J AU Wang, J Brinza, DE Young, DT Nordholt, JE Polk, JE Henry, MD Goldstein, R Hanley, JJ Lawrence, DJ Shappirio, M AF Wang, J Brinza, DE Young, DT Nordholt, JE Polk, JE Henry, MD Goldstein, R Hanley, JJ Lawrence, DJ Shappirio, M TI Deep Space One investigations of ion propulsion plasma environment SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID CONTAMINATION AB Deep Space One (DSI) is the first interplanetary spacecraft operated on solar electric propulsion. One of the primary investigations of DSI is to characterize ion propulsion-induced plasma interactions and their effects on spacecraft and solar wind measurements based on two plasma diagnostic packages. The first in situ measurements of an ion propulsion-induced plasma environment obtained from an interplanetary spacecraft are reported. Analysis of the measurements reveals interesting correlations between the induced charge-exchange plasma environment and thruster operating conditions. Sensors near the thruster exit measured charge-exchange ions with a number density of similar to 10(6) cm(-3) and a current density of similar to 10(-7) A/cm(-2) under typical thruster operating conditions, a result in good agreement with preflight predictions based on computer particle simulations. Observations on the opposite side from the thruster suggest that the dominant factor for charge-exchange ion backflow is the potential distribution surrounding the spacecraft rather than the charge-exchange ion production rate. C1 CALTECH, Jet Prop Lab, Measurement Test & Environm Support Sect, Pasadena, CA 91109 USA. SW Res Inst, Dept Space Sci, San Antonio, TX 78228 USA. Univ Calif Los Alamos Natl Lab, Space & Atmospher Sci Grp, Los Alamos, NM 87545 USA. CALTECH, Jet Prop Lab, Avion Syst Engn Sect, Pasadena, CA 91109 USA. CALTECH, Jet Prop Lab, Adv Propuls Technol Grp, Pasadena, CA 91109 USA. RP Wang, J (reprint author), CALTECH, Jet Prop Lab, Measurement Test & Environm Support Sect, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Lawrence, David/E-7463-2015 OI Lawrence, David/0000-0002-7696-6667 NR 16 TC 19 Z9 21 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 SEP-OCT PY 2000 VL 37 IS 5 BP 545 EP 555 DI 10.2514/2.3608 PG 11 WC Engineering, Aerospace SC Engineering GA 364LN UT WOS:000089894000001 ER PT J AU Grodsinsky, CM Whorton, MS AF Grodsinsky, CM Whorton, MS TI Survey of active vibration isolation systems for microgravity applications SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID DESIGN AB In view of the utility of space vehicles as orbiting science laboratories, the need for vibration isolation systems for acceleration-sensitive experiments has gained increasing visibility. To date, three active microgravity vibration isolation systems have successfully been demonstrated in Right. A tutorial discussion of the microgravity vibration isolation problem, including a description of the acceleration environment of the International Space Station and attenuation requirements, as well as a comparison of the dynamics of passive isolation, active rack-level isolation, and active payload-level isolation is provided, The flight test results of the three demonstrated systems: suppression of transient accelerations by levitation, the microgravity vibration isolation mount, and the active rack isolation system are surveyed. C1 Bicron Corp, Newbury, OH 44065 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Grodsinsky, CM (reprint author), Zin Technol, Micrograv Environm Program, 3000 Aerosp Pkwy, Brook Pk, OH 44142 USA. NR 14 TC 19 Z9 22 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 SEP-OCT PY 2000 VL 37 IS 5 BP 586 EP 596 DI 10.2514/2.3631 PG 11 WC Engineering, Aerospace SC Engineering GA 364LN UT WOS:000089894000007 ER PT J AU Johnston, JD Thornton, EA AF Johnston, JD Thornton, EA TI Thermally induced dynamics of satellite solar panels SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Thermally induced structural motions are known to affect the attitude dynamics of low Earth orbiting satellites during eclipse transitions. Motions of flexible appendages such as solar panels lead to rigid body rotations of the entire satellite because the total angular momentum of the system is conserved, These potentially large attitude disturbances may violate pointing accuracy and jitter requirements. One type of thermally induced dynamics exhibited by solar panels is thermal snap. The Upper Atmosphere Research Satellite is a prominent example of a satellite that experiences thermal snap disturbances during eclipse transitions. This paper describes recent studies of thermally induced dynamics of solar panels, including an analysis of satellite attitude dynamics resulting from thermally induced structural motions and a laboratory investigation of the thermal-structural performance of a satellite solar panel. Analytical and experimental results demonstrate thermal bending deformations with acceleration transients that have characteristic thermal snap disturbance histories in response to rapid changes in heating. The studies show that solar panel thermal snap disturbances are caused by through-the-thickness temperature differences that vary at a nonconstant rate. Finite element analysis correctly predicts the thermal snap phenomenon observed in the solar panel experiments. C1 Univ Virginia, Dept Mech & Aerosp Engn, Charlottesville, VA 22903 USA. RP Johnston, JD (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 13 TC 17 Z9 23 U1 1 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 SEP-OCT PY 2000 VL 37 IS 5 BP 604 EP 613 DI 10.2514/2.3633 PG 10 WC Engineering, Aerospace SC Engineering GA 364LN UT WOS:000089894000009 ER PT J AU Clark, RL Cox, DE AF Clark, RL Cox, DE TI Active control design for acoustic radiation using mixed-norm optimization SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Letter ID OUTPUT AB Linear matrix inequalities were applied to design a mixed H-2/H-infinity feedback control compensator for a structural acoustic system. The compensator was designed to minimize the H-2 norm of radiation filters while constraining the H-infinity norm through the control path to be less than unity. A trade-off between minimizing sound power radiated and maximum rms gain in the control path resulted in a reliable and robust means of designing compensators for structural acoustic control. (C) 2000 Acoustical Society of America. [S0001-4966(00)02609-6]. C1 Duke Univ, Dept Mech Engn & Mat Sci, Durham, NC 27708 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Clark, RL (reprint author), Duke Univ, Dept Mech Engn & Mat Sci, Durham, NC 27708 USA. NR 14 TC 3 Z9 3 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD SEP PY 2000 VL 108 IS 3 BP 1345 EP 1348 DI 10.1121/1.1288410 PN 1 PG 4 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA 352RD UT WOS:000089230900044 ER PT J AU Joshi, JA Hogan, JA Cowan, RM Strom, PF Finstein, MS AF Joshi, JA Hogan, JA Cowan, RM Strom, PF Finstein, MS TI Biological removal of gaseous ammonia in biofilters: Space travel and earth-based applications SO JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION LA English DT Article ID AIR-POLLUTION CONTROL; AUTOTROPHIC NITRIFICATION; CONTROL TECHNOLOGY; BIOFILTRATION; EMISSIONS; BACTERIA; ACID; ODOR; SOIL; VOC AB Gaseous NH3 removal was studied in laboratory-scale biofilters (14-L reactor volume) containing perlite inoculated with a nitrifying enrichment culture. These biofilters received 6 L/min of airflow with inlet NH3 concentrations of 20 or 50 ppm, and removed more than 99.99% of the NH3 for the period of operation (101, 102 days). Comparison between an active reactor and an autoclaved control indicated that NH3 removal resulted from nitrification directly, as well as from enhanced absorption resulting from acidity produced by nitrification. Spatial distribution studies (20 ppm only) after 8 days of operation showed that nearly 95% of the NH3 could be accounted for in the lower 25% of the biofilter matrix, proximate to the port of entry. Periodic analysis of the biofilter material (20 and 50 ppm) showed accumulation of the nitrification product NO3- early in the operation, but later both NO2- and NO3- accumulated. Additionally, the N-mass balance accountability dropped from near 100% early in the experiments to similar to 95 and 75% for the 20- and 50-ppm biofilters, respectively. A partial contributing factor to this drop in mass balance accountability was the production of NO and N2O, which were detected in the biofilter exhaust. C1 Rutgers State Univ, NASA,Specialized Ctr Res & Training, Cook Coll, New Brunswick, NJ 08901 USA. Rutgers State Univ, Cook Coll, Dept Environm Sci, New Brunswick, NJ 08901 USA. RP Joshi, JA (reprint author), Rutgers State Univ, NASA,Specialized Ctr Res & Training, Cook Coll, New Brunswick, NJ 08901 USA. NR 35 TC 19 Z9 21 U1 1 U2 3 PU AIR & WASTE MANAGEMENT ASSOC PI PITTSBURGH PA ONE GATEWAY CENTER, THIRD FL, PITTSBURGH, PA 15222 USA SN 1047-3289 J9 J AIR WASTE MANAGE JI J. Air Waste Manage. Assoc. PD SEP PY 2000 VL 50 IS 9 BP 1647 EP 1654 PG 8 WC Engineering, Environmental; Environmental Sciences; Meteorology & Atmospheric Sciences SC Engineering; Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 358LD UT WOS:000089558800007 PM 11055161 ER PT J AU Xu, KM Randall, DA AF Xu, KM Randall, DA TI Explicit simulation of midlatitude cumulus ensembles: Comparison with ARM data SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID CLOUD-RADIATION INTERACTION; ICE-PHASE MICROPHYSICS; SINGLE-COLUMN MODELS; MOISTURE BUDGETS; SQUALL LINE; NUMERICAL-SIMULATION; MACROSCOPIC BEHAVIOR; CONVECTIVE SYSTEM; HEAT; PARAMETERIZATION AB This study describes some results from several simulations of cumulus ensembles at the Southern Great Plains site of the Atmospheric Radiation Measurement (ARM) program during the July 1995 Intensive Observation Period (IOP). A 2D cloud ensemble model (CEM) is used to simulate the macroscopic properties of midlatitude cumulus ensembles. The observed large-scale, horizontal advective tendencies and large-scale vertical velocity or the total advective tendencies are used to drive the GEM, in addition to nudging of the simulated, domain-averaged horizontal wind components toward the observed winds. A detailed comparison with available observations and tropical convection is made in this study. In general, the GEM-simulated results agree reasonably well with the available observations from the July 1995 IOP. The differences between simulations and observations are, however, much larger than those obtained in tropical cases, especially those based on the Global Atmospheric Research Program Atlantic Tropical Experiment Phase III data. Significant differences exist between the statistical properties of tropical and midlatitude cumulus convection, especially in the vertical structures of the cumulus mass fluxes, apparent heat source (Q(1)), and apparent moisture sink (Q(2)). The strong variations of the subcloud-layer thermodynamic structure and the surface fluxes in midlatitude continents have large impacts on the heat and moisture budgets. The radiative budgets and satellite-observed cloud amounts are also compared with observations. Although the agreements are reasonably good, some deficiencies of the simulations and inadequate accuracy of large-scale advective tendencies can be clearly seen from the comparisons. Sensitivity tests are performed to address these issues. C1 Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO USA. RP Xu, KM (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 USA. EM k.m.xu@larc.nasa.gov RI Xu, Kuan-Man/B-7557-2013; Randall, David/E-6113-2011 OI Xu, Kuan-Man/0000-0001-7851-2629; Randall, David/0000-0001-6935-4112 NR 58 TC 15 Z9 15 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD SEP 1 PY 2000 VL 57 IS 17 BP 2839 EP 2858 DI 10.1175/1520-0469(2000)057<2839:ESOMCE>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 352QJ UT WOS:000089229100003 ER PT J AU Welker, R AF Welker, R TI Size distributions of particles extracted from different materials compared with the MIL-STD-1246 particle size distribution SO JOURNAL OF THE IEST LA English DT Article; Proceedings Paper CT 46th Annual Technical Meeting of the Institute-of-Environmental-Science-and-Technology CY APR 30-MAY 04, 2000 CL PROVIDENCE, RHODE ISLAND SP Inst Environm Sci & Technol DE particles; MIL-STD-1246; process control; precision cleaning AB MIL-STD-1246 particle-size distribution is the basis for specifying the particle cleanliness of surfaces for many governmental and industrial applications. MIL-STD-1246 states that naturally occurring particle contamination on surfaces follows a log-normal particle-size distribution, with a geometric mean of 1 mum, following a very precise size specification. However, the naturally occurring particle-size distribution may be a function of the material under examination or the prior cleaning or surface treatment history of the material. This paper explores the relation between the MIL-STD-1246 particle-size distribution and particle-size distributions measured after extraction followed by liquidborne particle-size distribution analysis. C1 RW Welker Associates, Northridge, CA USA. JPL, Pasadena, CA USA. RP Welker, R (reprint author), RW Welker Associates, Northridge, CA USA. NR 5 TC 3 Z9 3 U1 0 U2 0 PU INST ENVIRONMENTAL SCI TECHNOLOGY PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 USA SN 1098-4321 J9 J IEST JI J. IEST PD FAL PY 2000 VL 43 IS 4 BP 25 EP 29 PG 5 WC Engineering, Environmental; Environmental Sciences; Instruments & Instrumentation SC Engineering; Environmental Sciences & Ecology; Instruments & Instrumentation GA 383XP UT WOS:000165910200002 ER PT J AU Steininger, MK AF Steininger, MK TI Secondary forest structure and biomass following short and extended land-use in central and southern Amazonia SO JOURNAL OF TROPICAL ECOLOGY LA English DT Article DE amazon land use; biomass accumulation; fallow agriculture; forest regrowth ID RAIN-FOREST; BRAZILIAN AMAZON; PLANT SUCCESSION; WESTERN COLOMBIA; BAJO-CALIMA; LEAF-AREA; MANAGEMENT; VEGETATION; INVENTORY; LANDSCAPE AB A study was conducted on the effect of extended land-use on secondary forest biomass accumulation in the Amazon. Structural measurements were made in a series of secondary forest stands, from 4-30 y old, in Brazil and Bolivia. Half of the stands were forest regrowth following clearance and only 1 y of cultivation; the other half were regrowth following 4 y or more of continuous pasture in Brazil and three or more rotations of medium-fallow agriculture in Bolivia. Above-ground live biomass was estimated using published allometric equations. Total biomass ranged from 17 to 207 Mg ha(-1). Biomass of pioneer trees was poorly related to stand age, while that of later-successional trees increased linearly with age. Total biomass accumulation in Bolivia averaged 5.4 Mg ha(-1) y(-1) over the entire age sequence. Biomass accumulation for regrowth following short-term use was not greater than that for regrowth following medium-fallow agriculture. In Brazil, biomass accumulation averaged 9.1 Mg ha(-1) y(-1) over the first 12 y of regrowth and 5.9 Mg ha(-1) y(-1) over the entire age sequence. Biomass accumulation was significantly slower, around 5.0 Mg ha(-1) y(-1), for regrowth following continuous pasture than for regrowth following 1 y of cultivation. C1 Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RP Steininger, MK (reprint author), NASA, Goddard Space Flight Ctr, Code 923, Greenbelt, MD 20771 USA. NR 54 TC 59 Z9 65 U1 3 U2 21 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 USA SN 0266-4674 J9 J TROP ECOL JI J. Trop. Ecol. PD SEP PY 2000 VL 16 BP 689 EP 708 DI 10.1017/S0266467400001656 PN 5 PG 20 WC Ecology SC Environmental Sciences & Ecology GA 368LT UT WOS:000090119000005 ER PT J AU Lisle, J AF Lisle, J TI Drinking water treatment and regulations in the United States SO LABORATORY MEDICINE LA English DT Article AB Public drinking water in the United States is considered one of the safest sources of potable water in the world. This high quality of potability is possible due to excellent engineering designs and optimized treatment technologies and techniques. However, there is continued public concern over the quality of this drinking water due to drinking-water-related disease outbreaks each year. Common factors in all of these outbreaks include air absence of or a deficiency in 1 or more of the processes of conventional drinking water treatment (eg, filtration, disinfection). This article discusses the basic concepts of conventional drinking water treatment in the United States, with emphasis on those aspects that may compromise treatment efficiency. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Lisle, J (reprint author), Lockheed Martin, Mail Stop C23,2400 NASA Rd 1, Houston, TX 77058 USA. NR 7 TC 0 Z9 0 U1 2 U2 5 PU AMER SOC CLIN PATHOLOGISTS PI CHICAGO PA 2100 W HARRISON ST, CHICAGO, IL 60612 USA SN 0007-5027 J9 LAB MED JI Lab. Med. PD SEP PY 2000 VL 31 IS 9 BP 492 EP 496 PG 5 WC Medical Laboratory Technology SC Medical Laboratory Technology GA 350FQ UT WOS:000089090600016 ER PT J AU Del Castillo, CE Gilbes, F Coble, PG Muller-Karger, FE AF Del Castillo, CE Gilbes, F Coble, PG Muller-Karger, FE TI On the dispersal of riverine colored dissolved organic matter over the West Florida Shelf SO LIMNOLOGY AND OCEANOGRAPHY LA English DT Article ID ORINOCO-RIVER; OPTICAL-PROPERTIES; CARBON; FLUORESCENCE; ABSORPTION; WATERS; SEA; FLOCCULATION; CHLOROPHYLL; SPECTRA AB We investigated the optical properties of surface water in areas of the West Florida Shelf influenced by riverine discharge and by the occurrence of a phytoplankton plume. Results of absorption and fluorescence spectroscopy analyses and determination of dissolved organic carbon (DOC) concentration showed that the injection of riverine colored dissolved organic matter (CDOM) strongly affected the optical properties and DOC concentrations over the shelf. Riverborne nutrients contributed to an increase hi primary productivity. However, during the study period, the increase in primary productivity did not result in the production of significant amounts of CDOM. Fluorescence spectroscopy results showed that optical properties of riverine CDOM were lost close to the mouth of the rivers. A simple mathematical model describing mixing between riverine and marine end-members demonstrated that most of the observed changes in optical properties of CDOM along salinity gradients can be explained by mixing. Laboratory mixing experiments between riverine water and seawater indicated that flocculation of organic matter during estuarine mixing did not affect the optical properties of CDOM. C1 Univ S Florida, Dept Marine Sci, St Petersburg, FL 33701 USA. Univ Puerto Rico, Dept Ciencias Marinas, Mayaguez, PR 00680 USA. RP Del Castillo, CE (reprint author), NASA, Earth Syst Sci Off, Bldg 100 Code SA00, Stennis Space Ctr, MS 39529 USA. RI Del Castillo, Carlos/N-2601-2013 NR 27 TC 85 Z9 86 U1 3 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 SEP PY 2000 VL 45 IS 6 BP 1425 EP 1432 PG 8 WC Limnology; Oceanography SC Marine & Freshwater Biology; Oceanography GA 355QN UT WOS:000089396500022 ER PT J AU DellaCorte, C AF DellaCorte, C TI The things we carry - The toolbag of a tribologist can be large and heavy 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 SEP PY 2000 VL 56 IS 9 BP 3 EP 3 PG 1 WC Engineering, Mechanical SC Engineering GA 352QZ UT WOS:000089230500001 ER PT J AU Morales, W Handschuh, RF AF Morales, W Handschuh, RF TI A preliminary study on the vapor/mist phase lubrication of a spur gearbox SO LUBRICATION ENGINEERING LA English DT Article; Proceedings Paper CT 54th Annual Meeting of the Society-of-Tribologists-and-Lubrication-Engineers CY MAY 23-27, 1999 CL LAS VEGAS, NEVADA SP Soc Tribologists & Lubricat Engineers DE gears; non-ferrous alloys; vapor lubrication ID FILMS AB Organophosphates have been the primary compounds used in vapor/mist phase lubrication studies involving ferrous bearing material. Experimental results have indicated that the initial formation of an iron phosphate film on a rubbing ferrous surface, followed bf the growth (by cationic diffusion) of a lubricious pyrophosphate-type coating over the iron phosphate, is the reason organophosphates work well as vapor/mist phase lubricants. Recent work, however has shown that this mechanism leads to the depletion of surface iron atoms and to eventual lubrication failure. A new organophosphate formulation was developed which circumvents surface iron depletion. This formulation was tested by generating an iron phosphate coating on an aluminum surface. The new formulation was then used to vapor/mist phase lubricate a spur gear-box in a preliminary study. C1 NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NASA, Lewis Res Ctr, Army Res Lab, Vehicle Technol Ctr, Cleveland, OH 44135 USA. RP Morales, W (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. NR 12 TC 3 Z9 3 U1 0 U2 3 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 SEP PY 2000 VL 56 IS 9 BP 14 EP 19 PG 6 WC Engineering, Mechanical SC Engineering GA 352QZ UT WOS:000089230500006 ER PT J AU Miles, RB Grinstead, J Kohl, RH Diskin, G AF Miles, RB Grinstead, J Kohl, RH Diskin, G TI The RELIEF flow tagging technique and its application in engine testing facilities and for helium-air mixing studies SO MEASUREMENT SCIENCE AND TECHNOLOGY LA English DT Article DE fluid flow velocity; mixing; turbulence; vorticity; transport; RELIEF flow tagging; Raman excitation; oxygen; oxygen laser-induced fluorescence; engine inlet monitoring; flow field monitoring; combustion diagnostics; mixing studies; turbulent studies ID VELOCITY-MEASUREMENT; VELOCIMETRY; O2 AB Raman excitation plus laser-induced electronic fluorescence (RELIEF) images the motion of oxygen molecules in air and other gas mixtures. This is accomplished by tagging oxygen molecules through vibrational excitation and imaging them after a short period of time by laser-induced electronic fluorescence. The vibrational lifetime of oxygen is sufficiently long and the signal sufficiently strong to allow this technique to be used over a wide range of how conditions, from low subsonic to hypersonic, and in a variety of gas mixtures including high humidity environments. The utilization of a molecular tagging technique such as this is critical for environments in which seeding is impossible or unreliable and for measurements in which a wide range of scales needs to be observed simultaneously. Two experiments which have been conducted at national laboratories in medium- to large-scale facilities are reported. At the Arnold Engineering Development Center, RELIEF was used to examine velocity in a 1 m diameter tunnel for applications in the area of engine testing. At the NASA Langley Research Center, RELIEF is being used to examine supersonic mixing of helium in air in a coaxial jet in association with studies of fuel-air mixing in hypersonic engines. These applications are two examples of the wide range of practical uses for this new technology. C1 Princeton Univ, Dept Mech & Aerosp Engn, Princeton, NJ 08544 USA. Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA. Ronald H Kohl & Associates, Tullahoma, TN 37388 USA. NASA, Langley Res Ctr, Hyperson Airbreathing Prop Branch, Hampton, VA 23681 USA. RP Princeton Univ, Dept Mech & Aerosp Engn, Room D-414 Engn Quadrangle,Olden St, Princeton, NJ 08544 USA. EM miles@princeton.edu; jhg@nist.gov; kohl@cafes.net; g.s.diskin@larc.nasa.gov NR 24 TC 31 Z9 31 U1 0 U2 6 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0957-0233 EI 1361-6501 J9 MEAS SCI TECHNOL JI Meas. Sci. Technol. PD SEP PY 2000 VL 11 IS 9 BP 1272 EP 1281 DI 10.1088/0957-0233/11/9/304 PG 10 WC Engineering, Multidisciplinary; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 354TB UT WOS:000089344800005 ER PT J AU Balla, RJ Exton, RJ AF Balla, RJ Exton, RJ TI Thermometry in air by optically exciting the I-2 Cordes bands SO MEASUREMENT SCIENCE AND TECHNOLOGY LA English DT Article DE optical instrumentation; laser-induced ultraviolet iodine fluorescence; wake thermometry ID LASER-INDUCED FLUORESCENCE; ARF EXCIMER-LASER; MOLECULAR-IODINE; I2; STATE; ABSORPTION; FLOWS; TRANSITION; CONSTANTS; SPECTRUM AB An optical method is described to perform instantaneous thermometry along a line in low-density air seeded with it. Laser-induced fluorescence is generated by exciting the I-2 Cordes bands (D (1)Sigma(u)(+) <--X (1)Sigma(g)(+)) with a tunable ArF excimer laser near 193 nm. Temperatures from 295 to 648 K are measured by fitting the I-2 emission spectrum from 188 to 195 nm to a vibrational Boltzmann distribution. Uncertainties for average measurements are typically +/-5% (+/-1 sigma). C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, MS 493, Hampton, VA 23681 USA. EM r.j.balla@larc.nasa.gov NR 33 TC 2 Z9 2 U1 1 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0957-0233 EI 1361-6501 J9 MEAS SCI TECHNOL JI Meas. Sci. Technol. PD SEP PY 2000 VL 11 IS 9 BP 1319 EP 1327 DI 10.1088/0957-0233/11/9/309 PG 9 WC Engineering, Multidisciplinary; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 354TB UT WOS:000089344800010 ER PT J AU Briggs, G AF Briggs, G TI "Follow the water" SO METEORITICS & PLANETARY SCIENCE LA English DT Editorial Material C1 NASA, Ames Res Ctr, Ctr Mars Explorat, Moffett Field, CA 94035 USA. RP Briggs, G (reprint author), NASA, Ames Res Ctr, Ctr Mars Explorat, Mail Code 239-20, Moffett Field, CA 94035 USA. NR 5 TC 2 Z9 2 U1 1 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 IS 5 BP 892 EP 893 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 361RF UT WOS:000089736400002 ER PT J AU Kletetschka, G Wasilewski, PJ Taylor, PT AF Kletetschka, G Wasilewski, PJ Taylor, PT TI Mineralogy of the sources for magnetic anomalies on Mars SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID FE-TI-OXIDES; ROCKS; METEORITES; LABRADOR; HEMATITE; SPECTRA; FIELD AB Recent discovery of intense magnetic anomalies on Mars, which are due to remanent magnetization, requires some explanation for the possible minerals responsible for the anomalous signature. Thermoremanent magnetization (TRM) in single domain (SD) and multidomain (MD) sized magnetite, hematite, and pyrrhotite, all potential minerals, are considered. The intensity of TRM (in 0.05 mT) is in descending order: SD-sized magnetite, SD-sized pyrrhotite, MD-sized hematite, MD-sized pyrrhotite, MD-sized magnetite, SD-sized hematite. The TRM intensity is <4% of the saturation isothermal remanence (SIRM) for all but the MD hematite, which may have >50% of the SIRM. Each of these minerals and estimated concentrations of magnetic remanence carriers (assumed to be titanomagnetite) in the Shergotty-Nakhla-Chassigny martian meteorites are used in a thin sheet approximation model to reveal the concentration of each mineral required for the generation of an observed magnetic anomaly (1500 nT at 100 km altitude) assuming TRM acquisition in a 0.05 mT magnetic field. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kletetschka, G (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 691,921, Greenbelt, MD 20771 USA. EM gunther@denali.gsfc.nasa.gov RI Kletetschka, Gunther/C-9996-2011 OI Kletetschka, Gunther/0000-0002-0645-9037 NR 45 TC 48 Z9 48 U1 1 U2 10 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 IS 5 BP 895 EP 899 PG 5 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 361RF UT WOS:000089736400004 ER PT J AU Mikouchi, T Yamada, I Miyamoto, M AF Mikouchi, T Yamada, I Miyamoto, M TI Symplectic exsolution in olivine from the Nakhla martian meteorite SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID SNC METEORITE; PARENT MAGMA; PETROGENESIS; INCLUSIONS; OXIDATION AB The Nakhla meteorite, commonly accepted to have originated from Mars, is a cumulus clinopyroxenite with similar to 10 vol% of Fe-rich olivine. Almost all olivine grains in Nakhla contain dark lamellar inclusions (less than 2-3 mu m wide). High-resolution scanning and transmission electron microscopy revealed that the inclusions are complex intergrowths of augite and magnetite. Such a symplectic intergrowth of augite and magnetite in olivine was known in some terrestrial rocks, lunar rocks, and a few meteorites. The inclusion in Nakhla olivine is the first symplectite found in a martian rock. Apparently, the presence of Fe3+ in olivine under an oxidizing condition on Mars caused symplectic exsolution at high temperature (>900 degrees C) during cooling. C1 Univ Tokyo, Grad Sch Sci, Inst Mineral, Bunkyo Ku, Tokyo 1130033, Japan. NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch, Houston, TX 77058 USA. RP Mikouchi, T (reprint author), Univ Tokyo, Grad Sch Sci, Inst Mineral, Bunkyo Ku, 7-3-1 Hongo, Tokyo 1130033, Japan. NR 27 TC 31 Z9 33 U1 0 U2 3 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 IS 5 BP 937 EP 942 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 361RF UT WOS:000089736400009 ER PT J AU Browning, L McSween, HY Zolensky, ME AF Browning, L McSween, HY Zolensky, ME TI On the origin of rim textures surrounding anhydrous silicate grains in CM carbonaceous chondrites SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID AQUEOUS ALTERATION; CHONDRULE RIMS; MASS BALANCE; MINERALOGY; MATRIX; SERPENTINITE; CONSTRAINTS; METEORITE AB Fine-grained, optically opaque rims coat individual olivine and pyroxene grains in CM matrices and chondrules. Bulk chemical analyses and observations of these rims indicate the presence of phyllosilicates and disseminated opaques. Because phyllosilicates could not have survived the chondrule formation process, chondrule silicate rims must have formed entirely by late-state aqueous reactions. As such, these textures provide a useful benchmark for isolating alteration features from more complex CM matrix materials. Both chondrule silicate and matrix silicate rims exhibit morphological features commonly associated with advancing stages of replacement reactions in terrestrial serpentinites. Contacts between many matrix silicate rims and the adjacent matrix materials suggest that these rims formed entirely by aqueous reactions in a parent-body setting. This contrasts with previous assertions that rim textures can only form by the accretion of nebular dust but does not imply an origin for the rims surrounding other types of CM core components, such as chondrules. C1 Univ Hawaii, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Univ Tennessee, Dept Geol Sci, Knoxville, TN 37996 USA. NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. RP Browning, L (reprint author), SW Res Inst, Ctr Nucl Waste Regulatory Anal, 6220 Culebra Rd, San Antonio, TX 78238 USA. NR 35 TC 17 Z9 17 U1 0 U2 4 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 IS 5 BP 1015 EP 1023 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 361RF UT WOS:000089736400015 ER PT J AU Pieters, CM Taylor, LA Noble, SK Keller, LP Hapke, B Morris, RV Allen, CC McKay, DS Wentworth, S AF Pieters, CM Taylor, LA Noble, SK Keller, LP Hapke, B Morris, RV Allen, CC McKay, DS Wentworth, S TI Space weathering on airless bodies: Resolving a mystery with lunar samples SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID SPECTRAL PROPERTIES; ORDINARY CHONDRITE; ASTEROIDS; METEORITE; VESTA; SPECTROSCOPY; REGOLITH; FRACTION; SOIL; MOON AB Using new techniques to examine the products of space weathering of lunar soils, we demonstrate that nanophase reduced iron (npFe(0)) is produced on the surface of grains by a combination of vapor deposition and irradiation effects. The optical properties of soils (both measured and modeled) are shown to be highly dependent on the cumulative amount of npFe(0), which varies with different starting materials and the energetics of different parts of the solar system. The measured properties of intermediate albedo asteroids, the abundant S-type asteroids in particular, are shown to directly mimic the effects predicted for small amounts of npFe(0) on grains of an ordinary chondrite regolith. This measurement and characterization of space weathering products seems to remove a final obstacle hindering a link between the abundant ordinary chondrite meteorites and common asteroids. C1 Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. Univ Tennessee, Dept Geol Sci, Knoxville, TN 37966 USA. MVA Inc, Norcross, GA 30093 USA. Univ Pittsburgh, Dept Geol & Planetary Sci, Pittsburgh, PA 15260 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Space Operat, Houston, TX 77058 USA. RP Pieters, CM (reprint author), Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. RI Noble, Sarah/D-7614-2012 NR 66 TC 326 Z9 330 U1 2 U2 21 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 IS 5 BP 1101 EP 1107 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 361RF UT WOS:000089736400022 ER PT J AU Ali, A Kooi, SE Leskiw, BD Castleman, AW AF Ali, A Kooi, SE Leskiw, BD Castleman, AW TI An observation of mass-independent oxygen-isotopic effects in laboratory studies of the formation of cosmic silicates. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract ID METEORITES; FRACTIONATION; OZONE C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Penn State Univ, Dept Chem, University Pk, PA 16802 USA. NR 10 TC 0 Z9 0 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A20 EP A20 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400010 ER PT J AU Amari, S Gao, X Nittler, LR Zinner, E Jose, J Hernanz, M Lewis, RS AF Amari, S Gao, X Nittler, LR Zinner, E Jose, J Hernanz, M Lewis, RS TI Presolar grains from novae. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract ID SILICON-CARBIDE GRAINS; NUCLEOSYNTHESIS; METEORITES C1 Washington Univ, Dept Phys, Space Sci Lab, St Louis, MO 63130 USA. Scripps Res Inst, La Jolla, CA 92037 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Politecn Cataluna, E-08800 Barcelona, Spain. Inst Ciencia Mat Barcelona, Inst Esutdis Especials Catalunya, E-08034 Barcelona, Spain. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. EM sa@howdy.wustl.edu NR 10 TC 0 Z9 0 U1 0 U2 0 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 SEP PY 2000 VL 35 SU S BP A20 EP A21 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400011 ER PT J AU Bell, JF Veverka, J Belton, M Benkhoff, J Cheng, A Clark, B Cochran, A Farquhar, R Feldman, P Kissel, J Mahaffy, P Malin, M Murchie, S Niemann, H Owen, T Schwehm, G Squyres, S Thomas, P Yeomans, D AF Bell, JF Veverka, J Belton, M Benkhoff, J Cheng, A Clark, B Cochran, A Farquhar, R Feldman, P Kissel, J Mahaffy, P Malin, M Murchie, S Niemann, H Owen, T Schwehm, G Squyres, S Thomas, P Yeomans, D TI Contour: A discovery mission to explore the diversity of cometary nuclei. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Cornell Univ, Ithaca, NY 14853 USA. Kitt Peak Natl Observ, Tucson, AZ 85726 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Lockheed Martin, Bethesda, MD 20817 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Malin Space Sci Syst Inc, San Diego, CA USA. Univ Hawaii, Honolulu, HI 96822 USA. European Space Agcy, Paris, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RI Wellnitz, Dennis/B-4080-2012; McFadden, Lucy-Ann/I-4902-2013; Murchie, Scott/E-8030-2015; Izenberg, Noam/F-3952-2015 OI McFadden, Lucy-Ann/0000-0002-0537-9975; Murchie, Scott/0000-0002-1616-8751; Izenberg, Noam/0000-0003-1629-6478 NR 0 TC 6 Z9 6 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A23 EP A24 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400017 ER PT J AU Bodnar, RJ Zolensky, ME AF Bodnar, RJ Zolensky, ME TI Fluid inclusions in meteorites: Are they useful, and why are they so hard to find? SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Virginia Polytech Inst & State Univ, Dept Geol Sci, Blacksburg, VA 24061 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RI Bodnar, Robert/A-1916-2009 NR 5 TC 1 Z9 1 U1 1 U2 6 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A29 EP A30 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400028 ER PT J AU Bogard, DD Garrison, DH AF Bogard, DD Garrison, DH TI Meteorite argon-39-argon-40 ages: Accuracy and interpretation. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Planetary Sci Div, Houston, TX 77058 USA. Lockheed Martin Corp, Houston, TX 77058 USA. NR 3 TC 3 Z9 3 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A30 EP A30 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400029 ER PT J AU Brownlee, DE Tsou, P Clark, B Hanner, MS Horz, F Kissel, J McDonnell, JAM Newburn, RL Sandford, S Sekanina, Z Tuzzolino, AJ Zolensky, M AF Brownlee, DE Tsou, P Clark, B Hanner, MS Horz, F Kissel, J McDonnell, JAM Newburn, RL Sandford, S Sekanina, Z Tuzzolino, AJ Zolensky, M TI Stardust: A comet sample return mission. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Univ Washington, Dept Astron, Seattle, WA 98195 USA. Jet Propuls Lab, Pasadena, CA 91011 USA. Lockheed Martin Marietta Astronaut, Denver, CO 80201 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Max Planck Inst Extraterr Phys, D-37075 Garching, Germany. Univ Kent, Unit Space Sci & Astrophys, Canterbury CT2 7NR, Kent, England. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Chicago, Lab Astrophys & Space Res, Chicago, IL 60637 USA. NR 0 TC 13 Z9 13 U1 0 U2 2 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 1086-9379 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A35 EP A35 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400040 ER PT J AU Chen, JH Papanastassiou, DA Wasserburg, GJ AF Chen, JH Papanastassiou, DA Wasserburg, GJ TI Rhenium-osmium fractionation in group IIIAB iron meteorites. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract ID ISOTOPE SYSTEMATICS; GROUP-IIAB C1 CALTECH, Charles Arms Lab, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. NR 7 TC 0 Z9 0 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A39 EP A40 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400050 ER PT J AU Fagan, TJ Bunch, TE Wittke, JH Jarosewich, E Clayton, RN Mayeda, T Eugster, O Lorenzetti, S Keil, K Taylor, GJ AF Fagan, TJ Bunch, TE Wittke, JH Jarosewich, E Clayton, RN Mayeda, T Eugster, O Lorenzetti, S Keil, K Taylor, GJ TI Northwest Africa 032, a new lunar mare basalt. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. No Arizona Univ, Dept Geol, Flagstaff, AZ 86011 USA. Smithsonian Inst, Dept Mineral Sci, Washington, DC 20560 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Bern, Inst Phys, CH-3012 Bern, Switzerland. RI Lorenzetti, Silvio/B-1188-2009 OI Lorenzetti, Silvio/0000-0002-8339-8960 NR 5 TC 7 Z9 7 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A51 EP A52 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400075 ER PT J AU Garrison, DH Bogard, DD AF Garrison, DH Bogard, DD TI Cosmogenic and trapped noble gases in the Los Angeles martian meteorite. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Planetary Sci Div, Houston, TX 77058 USA. Lockheed Martin Corp, Houston, TX 77058 USA. NR 4 TC 10 Z9 10 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A58 EP A58 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400086 ER PT J AU Gibson, EK McKay, DS Thomas-Keprta, K Westall, F Clemett, SJ AF Gibson, EK McKay, DS Thomas-Keprta, K Westall, F Clemett, SJ TI What is the status of the hypothesis of evidence of biogenic activity within martian meteorites: Alive or dead? SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Lockheed Martin, Houston, TX 77058 USA. Lunar & Planetary Inst, Houston, TX 77058 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A60 EP A60 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400090 ER PT J AU Grady, MM Wright, IP Verchovsky, AB Pillinger, CT Zolensky, ME AF Grady, MM Wright, IP Verchovsky, AB Pillinger, CT Zolensky, ME TI Carbon (and eventually nitrogen and argon) in the Tagish Lake (Yukon) carbonaceous chondrite. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Nat Hist Museum, Dept Mineral, London SW7 5BD, England. Open Univ, Planetary Sci Res Inst, Milton Keynes MK7 6AA, Bucks, England. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. EM mmg@nhm.ac.uk NR 4 TC 2 Z9 2 U1 0 U2 0 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 SEP PY 2000 VL 35 SU S BP A62 EP A63 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400095 ER PT J AU Hildebrand, AR Brown, PG Zolensky, ME Lindstrom, D Wacker, J Tagliaferri, E AF Hildebrand, AR Brown, PG Zolensky, ME Lindstrom, D Wacker, J Tagliaferri, E TI The fireball and strewn field of the Tagish Lake meteorites, fell January 18, 2000, in northern British Columbia. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Univ Calgary, Dept Geol & Geophys, Calgary, AB T2N 1N4, Canada. Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. ET Space Syst, Camarillo, CA 93012 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A73 EP A73 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400114 ER PT J AU Hill, HGM Nuth, JA AF Hill, HGM Nuth, JA TI Nebular hydrocarbon synthesis in the laboratory: The catalytic potential of synthetic silicate dust. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. RI Nuth, Joseph/E-7085-2012 NR 4 TC 2 Z9 2 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A73 EP A74 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400115 ER PT J AU Ivanov, AV Zolensky, ME Yang, SV Ariskin, AA AF Ivanov, AV Zolensky, ME Yang, SV Ariskin, AA TI The Kaidun meteorite: Fast crystallization of a fragment from a superheated melt. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 VI Vernadskii Inst Geochem & Analyt Chem, Moscow 117975, Russia. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin, Houston, TX 77058 USA. NR 3 TC 7 Z9 8 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A82 EP A83 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400133 ER PT J AU Ivanov, AV Zolensky, ME Yang, SV AF Ivanov, AV Zolensky, ME Yang, SV TI The Kaidun meteorite: Evidence for aqueous alteration and precipitation. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 VI Vernadskii Inst Geochem & Analyt Chem, Moscow 117975, Russia. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin, Houston, TX 77058 USA. NR 3 TC 7 Z9 8 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A82 EP A82 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400132 ER PT J AU Lofgren, GE AF Lofgren, GE TI Partial melting model for formation of aggregate and porphyritic chondrules. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 9 TC 3 Z9 3 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A99 EP A100 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400166 ER PT J AU Meibom, A Desch, SJ Petaev, MI Krot, AN Cuzzi, JN Wood, JA Keil, K AF Meibom, A Desch, SJ Petaev, MI Krot, AN Cuzzi, JN Wood, JA Keil, K TI An astrophysical model for the formation of zoned iron-nickel metal grains in the Bencubbin/CH-like chondrites Queen Alexandra range 94411 and Hammadah al Hamra 237. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Stanford Univ, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. NR 7 TC 3 Z9 3 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A107 EP A107 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400182 ER PT J AU Mikouchi, T AF Mikouchi, T TI Pyroxene and plagioclase in the Los Angeles martian meteorite: Comparison with the Queen Alexandra range 94201 martian meteorite and the Asuka 881757 lunar meteorite SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Univ Tokyo, Dept Earth & Planetary Sci, Tokyo 1130033, Japan. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 7 TC 6 Z9 6 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A110 EP A110 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400187 ER PT J AU Mikouchi, T McKay, GA Le, L AF Mikouchi, T McKay, GA Le, L TI Experimental crystallization of the Asuka 881371 (angrite) groundmass composition: Implications for crystallization histories of Sahara 99555. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Univ Tokyo, Dept Earth & Planetary Sci, Tokyo 1130033, Japan. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin, Houston, TX 77058 USA. NR 2 TC 6 Z9 6 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A110 EP A111 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400188 ER PT J AU Mittlefehldt, DW Lindstrom, MM AF Mittlefehldt, DW Lindstrom, MM TI Minor-element compositions of Acapulco-like and Lodran-like achondrite pyroxenes. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Lockheed Martin, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A111 EP A112 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400190 ER PT J AU Nittler, LR McCoy, TJ AF Nittler, LR McCoy, TJ TI Carbon isotopes in graphite from lodranite Graves Nunataks 95209. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. NR 5 TC 3 Z9 3 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A120 EP A121 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400207 ER PT J AU Nuth III, JA Nittler, LR AF Nuth III, JA Nittler, LR TI Planetary accretion, oxygen isotopes, and the Central Limit Theorem. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Goddard Space Flight Ctr, Astrochem Branch, Greenbelt, MD 20771 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A121 EP A121 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400208 ER PT J AU Nyquist, LE Reese, YD Wiesmann, H Shih, CY Schwandt, C AF Nyquist, LE Reese, YD Wiesmann, H Shih, CY Schwandt, C TI Rubidium-strontium age of the Los Angeles shergotitite. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract ID DIFFERENTIATION; METEORITES C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin, Houston, TX 77058 USA. NR 8 TC 20 Z9 20 U1 0 U2 3 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A121 EP A122 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400209 ER PT J AU Pieters, CM Taylor, LA Noble, SK Keller, LP Hapke, B Morris, RV Allen, CC McKay, DS Wentworth, S AF Pieters, CM Taylor, LA Noble, SK Keller, LP Hapke, B Morris, RV Allen, CC McKay, DS Wentworth, S TI Space weathering on asteroids: A mystery resolved with lunar samples. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Brown Univ, Dept Geol Sci, Providence, RI 02912 USA. Univ Tennessee, Knoxville, TN 37996 USA. MVA Inc, Norcross, GA 30092 USA. Univ Pittsburgh, Pittsburgh, PA 15260 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin, Houston, TX 77058 USA. RI Noble, Sarah/D-7614-2012 NR 17 TC 1 Z9 1 U1 1 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A127 EP A128 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400220 ER PT J AU Sandford, SA Bernstein, MP Allamandola, LJ Gillette, JS Zare, RN AF Sandford, SA Bernstein, MP Allamandola, LJ Gillette, JS Zare, RN TI Interstellar ice photochemistry and the deuterium enrichment and chemical properties of meteoritic polycyclic aromatic hydrocarbons. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract ID INFRARED-EMISSION C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mountain View, CA 94043 USA. Stanford Univ, Dept Chem, Stanford, CA 94305 USA. EM ssandford@mail.arc.nasa.gov RI Zare, Richard/A-8410-2009 NR 9 TC 0 Z9 0 U1 0 U2 2 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 SEP PY 2000 VL 35 SU S BP A141 EP A141 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400246 ER PT J AU Sears, DWG Brownlee, DE Pieters, C Lindstrom, M Britt, D Clark, BC Gefert, L Gorevan, S Preble, JC AF Sears, DWG Brownlee, DE Pieters, C Lindstrom, M Britt, D Clark, BC Gefert, L Gorevan, S Preble, JC TI A multiple near-earth asteroid sample return mission called Hera. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Univ Arkansas, Ctr Space & Planetary Sci, Fayetteville, AR 72701 USA. Univ Washington, Seattle, WA 98195 USA. Brown Univ, Providence, RI 02912 USA. Univ Tennessee, Knoxville, TN 37996 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Lockheed Martin, Denver, CO 80202 USA. Honeybee Robot Inc, New York, NY 10012 USA. SpaceWorks Inc, Carefree, AZ 85377 USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A145 EP A145 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400255 ER PT J AU Sipiera, PP Hoover, RB Jerman, GA Butts, DG Garriott, OK Gruber, WJ Lovell, JA Pritzker, JN AF Sipiera, PP Hoover, RB Jerman, GA Butts, DG Garriott, OK Gruber, WJ Lovell, JA Pritzker, JN TI A preliminary report on the discovery of twenty stone meteorites from the Thiel Mountains and Patriot Hills, Antarctica. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Schmitt Meteorite Res Grp, Palatine, IL 60067 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Planetary Studies Fdn, Algonquin, IL 60102 USA. NR 5 TC 4 Z9 4 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A148 EP A149 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400262 ER PT J AU Thomas-Keprta, KL Clemett, SJ Bazylinski, DA Kirschvink, JL McKay, DS Wentworth, SJ Vali, H Gibson, EK AF Thomas-Keprta, KL Clemett, SJ Bazylinski, DA Kirschvink, JL McKay, DS Wentworth, SJ Vali, H Gibson, EK TI Biogenic martian magnetite crystals? A comparison of prismatic magnetite crystals in the Allan Hills 84001 carbonate globules with those from magnetotactic bacteria strain MV-1. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Lockheed Martin, Houston, TX 77058 USA. Iowa State Univ Sci & Technol, Ames, IA 50011 USA. CALTECH, Pasadena, CA 91125 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. McGill Univ, Montreal, PQ H3A 2A7, Canada. RI Vali, Hojatollah/F-3511-2012 OI Vali, Hojatollah/0000-0003-3464-9943 NR 2 TC 2 Z9 2 U1 0 U2 3 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A156 EP A156 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400277 ER PT J AU Trombka, JI Nittler, LR Boynton, WV Bruckner, J Squyres, SW Arnold, JR Evans, LG Gorenstein, P Hurley, KC McCoy, TJ Reedy, RC Bailey, S Burbine, TH Bhangoo, JS Clark, PE Floyd, SR Gold, RE McClanahan, TP McCartney, E Goldsten, JO McNutt, RL Mikheeva, I Murphy, ME Starr, RD AF Trombka, JI Nittler, LR Boynton, WV Bruckner, J Squyres, SW Arnold, JR Evans, LG Gorenstein, P Hurley, KC McCoy, TJ Reedy, RC Bailey, S Burbine, TH Bhangoo, JS Clark, PE Floyd, SR Gold, RE McClanahan, TP McCartney, E Goldsten, JO McNutt, RL Mikheeva, I Murphy, ME Starr, RD TI The chemical composition of asteroid 433 Eros: Preliminary results of the NEAR Shoemaker X-Ray/Gamma-Ray Spectrometer. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Arizona, Dept Planetary Sci, Tucson, AZ 85721 USA. Max Planck Inst Chem, D-55020 Mainz, Germany. Cornell Univ, Ithaca, NY 14853 USA. Univ Calif San Diego, La Jolla, CA 92093 USA. Comp Sci Corp, Syst Sci Div, Laurel, MD 20707 USA. Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. Univ Calif Berkeley, Space Sci Lab 7450, Berkeley, CA 94720 USA. Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. RI McNutt, Ralph/E-8006-2010 OI McNutt, Ralph/0000-0002-4722-9166 NR 6 TC 0 Z9 0 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A159 EP A160 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400284 ER PT J AU Veverka, J Robinson, M Thomas, P Murchie, S Bell, JF Izenberg, N Chapman, C Yeomans, DK AF Veverka, J Robinson, M Thomas, P Murchie, S Bell, JF Izenberg, N Chapman, C Yeomans, DK CA NEAR MSI NIS Team TI NEAR Shoemaker at Eros: Imaging and spectral results. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 Cornell Univ, Ctr Radiophys & Space Res, Ithaca, NY 14853 USA. Northwestern Univ, Evanston, IL USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA. SW Res Inst, Boulder, CO USA. Jet Prop Lab, Pasadena, CA USA. RI Murchie, Scott/E-8030-2015; Izenberg, Noam/F-3952-2015 OI Murchie, Scott/0000-0002-1616-8751; Izenberg, Noam/0000-0003-1629-6478 NR 2 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A164 EP A164 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400292 ER PT J AU Wieler, R Gunther, D Hattendorf, B Leya, I Pettke, T Vogel, N Zolensky, ME AF Wieler, R Gunther, D Hattendorf, B Leya, I Pettke, T Vogel, N Zolensky, ME TI The chemical composition and light noble gas data of halite in the Monahans regolithic breccia. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract ID INCLUSION-BEARING HALITE; ASTEROIDAL WATER C1 ETH Zurich, CH-8092 Zurich, Switzerland. ETH Zurich, CAB, CH-8092 Zurich, Switzerland. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RI Wieler, Rainer/A-1355-2010 OI Wieler, Rainer/0000-0001-5666-7494 NR 7 TC 2 Z9 2 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A170 EP A170 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400303 ER PT J AU Zolensky, ME Grady, MM Clayton, RN Mayeda, TK Hildebrand, AR Brown, PG Brook, JL Roots, CF AF Zolensky, ME Grady, MM Clayton, RN Mayeda, TK Hildebrand, AR Brown, PG Brook, JL Roots, CF TI Tagish Lake: A special new type 2 carbonaceous chondrite fall. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract ID OXYGEN C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Nat Hist Museum, London SW7 5BD, England. Univ Chicago, Chicago, IL 60637 USA. Univ Calgary, Calgary, AB T2N 1N4, Canada. Univ Western Ontario, London, ON N6A 3K7, Canada. Geol Survey Canada, Whitehorse, YT Y1A 2C6, Canada. NR 6 TC 4 Z9 4 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A178 EP A179 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400320 ER PT J AU Zolensky, ME AF Zolensky, ME TI The MUSES-C asteroid sample return mission. SO METEORITICS & PLANETARY SCIENCE LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 1 TC 4 Z9 4 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD SEP PY 2000 VL 35 SU S BP A178 EP A178 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 362PU UT WOS:000089787400319 ER PT J AU Perigaud, CM Cassou, C Dewitte, B Fu, LL Neelin, JD AF Perigaud, CM Cassou, C Dewitte, B Fu, LL Neelin, JD TI Using data and intermediate coupled models for seasonal-to-interannual forecasts SO MONTHLY WEATHER REVIEW LA English DT Article ID IN-SITU DATA; EL-NINO; DATA ASSIMILATION; OCEAN INITIALIZATION; TROPICAL PACIFIC; ATMOSPHERE MODEL; ZEBIAKS MODEL; ENSO; PREDICTION; IMPACT AB This paper provides a detailed illustration that it is beneficial for ENSO forecasting to improve in priority the model parameterizations, instead of increasing only the consistency of the initial conditions with the coupled model, Moreover it is shown that the latter can lead to misleading results. Using sea level data in addition to wind to initialize the Cane and Zebiak model does not improve El Nino forecasts. Nudging the observed wind to the model one to initialize the forecasts as proposed by Chen et al. also fails to correct the model deficiencies and degrades the initial conditions of the ocean and atmosphere. These failures are explained by large model errors in the off-equatorial sea level and wind anomalies that play a key role in the coupled behavior. The use of data to estimate new model parameterizations allows for significantly improving both the initial conditions and the forecasts up to 6-month lead time. This success holds for all the various initialization procedures used in this study. Because of erroneous winds simulated by the atmospheric component in the eastern Pacific, errors grow fast though. Replacing the atmospheric model by a statistical one results in more reliable predictions over 1980-98. Por lead times up to 1 yr, the model predicts well the observed anomalies between 1984 and 1993, including the sea level rises along the ITCZ after warm events and their subsequent equatorward migration. This success is attributed to the consistency between the observed anomalies over this period and the mechanisms involved in maintaining the oscillatory behavior of the model, including the off-equatorial meridional wind anomalies. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA USA. RP CALTECH, Jet Prop Lab, MS 300-323,4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM cp@pacific.jpl.nasa.gov RI Neelin, J. David/H-4337-2011 NR 34 TC 7 Z9 7 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 EI 1520-0493 J9 MON WEATHER REV JI Mon. Weather Rev. PD SEP PY 2000 VL 128 IS 9 BP 3025 EP 3049 DI 10.1175/1520-0493(2000)128<3025:UDAICM>2.0.CO;2 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 356UK UT WOS:000089461100001 ER PT J AU Ryan, BF Katzfey, JJ Abbs, DJ Jakob, C Lohmann, U Rockel, B Rotstayn, LD Stewart, RE Szeto, KK Tselioudis, G Yau, MK AF Ryan, BF Katzfey, JJ Abbs, DJ Jakob, C Lohmann, U Rockel, B Rotstayn, LD Stewart, RE Szeto, KK Tselioudis, G Yau, MK TI Simulations of a cold front by cloud-resolving, limited-area, and large-scale models, and a model evaluation using in situ and satellite observations SO MONTHLY WEATHER REVIEW LA English DT Article ID CUMULUS PARAMETERIZATION; THERMODYNAMIC STRUCTURE; LOWER TROPOSPHERE; PRECIPITATION; EVAPORATION; SYSTEMS; CLIMATE; SCHEME; MC2 AB The Global Energy and Water Cycle Experiment has identified the poor representation of clouds in atmospheric general circulation models as one of the major impediments for the use of these models in reliably predicting future climate change. One of the most commonly encountered types of cloud system in midlatitudes is that associated with cyclones. The purpose of this study is to investigate the representation of frontal cloud systems in a hierarchy of models in order to identify their relative weaknesses. The hierarchy of models was classified according to the horizontal resolution: cloud-resolving models (5-km resolution), limited-area models (20-km resolution), coarse-grid single-column models (300 km), and an atmospheric general circulation model (>100 km). The models were evaluated using both in situ and satellite data. The study shows. as expected. that the higher-resolution models give a more complete description of the front and capture many of the observed nonlinear features of the front. At the low resolution, the simulations are unable to capture the front accurately due to the lack of the nonlinear features seen in the high-resolution simulations. The model intercomparison identified problems in applying single-column models to rapidly advecting baroclinic systems. Mesoscale circulations driven by subgrid-scale dynamical, thermodynamical, and microphysical processes are identified as an important feedback mechanism Linking the frontal circulations and the cloud held. Finally it is shown that the same techniques used to validate climatological studies with International Satellite Cloud Climatology Project data are also valid for case studies. thereby providing a methodology to generalize the single case studies to climatological studies. C1 CSIRO, Div Atmospher Res, Aspendale, Vic 3195, Australia. ECMWF, Reading, Berks, England. Dalhousie Univ, Dept Phys, Halifax, NS B3H 3J5, Canada. GKSS Forschungszentrum Geesthacht GmbH, D-2054 Geesthacht, Germany. Atmospher Environm Serv, Downsview, ON, Canada. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. McGill Univ, Dept Atmospher & Ocean Sci, Montreal, PQ, Canada. RP Ryan, BF (reprint author), CSIRO, Div Atmospher Res, Private Bag 1, Aspendale, Vic 3195, Australia. RI Rotstayn, Leon/A-1756-2012; Katzfey, Jack/K-1231-2012; Lohmann, Ulrike/B-6153-2009; Jakob, Christian/A-1082-2010 OI Rotstayn, Leon/0000-0002-2385-4223; Katzfey, Jack/0000-0002-0604-8860; Lohmann, Ulrike/0000-0001-8885-3785; Jakob, Christian/0000-0002-5012-3207 NR 36 TC 30 Z9 30 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD SEP PY 2000 VL 128 IS 9 BP 3218 EP 3235 DI 10.1175/1520-0493(2000)128<3218:SOACFB>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 356UK UT WOS:000089461100010 ER PT J AU Dee, DP Todling, R AF Dee, DP Todling, R TI Data assimilation in the presence of forecast bias: The GEOS moisture analysis SO MONTHLY WEATHER REVIEW LA English DT Article ID ERROR COVARIANCE PARAMETERS; ATMOSPHERIC DATA ASSIMILATION; MAXIMUM-LIKELIHOOD-ESTIMATION; MODEL ERROR; PART I; ALGORITHM; SYSTEM AB The authors describe the application of the unbiased sequential analysis algorithm developed by Dee and da Silva to the Goddard Earth Observing System moisture analysis. The algorithm estimates the slowly varying, systematic component of model error from rawinsonde observations and adjusts the first-guess moisture field accordingly. Results of two seasonal data assimilation cycles show that moisture analysis bias is almost completely eliminated in all observed regions. The improved analyses cause a sizable reduction in the 6-h forecast bias and a marginal improvement in the error standard deviations. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Dee, DP (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Mail Code 910-3, Greenbelt, MD 20771 USA. NR 24 TC 76 Z9 77 U1 1 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD SEP PY 2000 VL 128 IS 9 BP 3268 EP 3282 DI 10.1175/1520-0493(2000)128<3268:DAITPO>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 356UK UT WOS:000089461100013 ER PT J AU Bikdash, M Kunchithapadam, V Ragunathan, K Homaifar, A AF Bikdash, M Kunchithapadam, V Ragunathan, K Homaifar, A TI Comparison of quasi bang-bang and sliding mode controls for a DC shunt motor with time delay SO NONLINEAR DYNAMICS LA English DT Article DE fuzzy logic control; quasi bang-bang; sliding mode; hybrid fuzzy PID AB We propose a hybrid fuzzy-linear controller for a nonlinear terminal voltage-controlled DC motor. The nonlinearity includes the effect of magnetization saturation and a nonlinear fan load. The input to the proposed Fuzzy Logic Controller (FLC) is an 'aggregate' error between the required and the actual rpm and its time derivatives. The FLC is designed to approximate a bang-bang controller and its coefficients are chosen as a tradeoff between short rise time, small steady-state errors, and control chattering. The FLC performance was compared to that of a well-known design; namely a sliding mode controller with a boundary layer. Although the FLC design procedure is easier, the performance of the two controllers are quite similar. Unfortunately, the FLC design was not robust enough to counter the effect of large time delays introduced by the power electronics interface. C1 N Carolina Agr & Tech State Univ, Dept Elect Engn, NASA, Autonomous Control Engn Ctr, Greensboro, NC 27411 USA. RP Bikdash, M (reprint author), N Carolina Agr & Tech State Univ, Dept Elect Engn, NASA, Autonomous Control Engn Ctr, Greensboro, NC 27411 USA. NR 14 TC 2 Z9 2 U1 0 U2 2 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0924-090X EI 1573-269X J9 NONLINEAR DYNAM JI Nonlinear Dyn. PD SEP PY 2000 VL 23 IS 1 BP 87 EP 102 DI 10.1023/A:1008333819832 PG 16 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 350YZ UT WOS:000089130400006 ER PT J AU Chen, PC Bowers, CW Content, DA Marzouk, M Romeo, RC AF Chen, PC Bowers, CW Content, DA Marzouk, M Romeo, RC TI Advances in very lightweight composite mirror technology SO OPTICAL ENGINEERING LA English DT Article DE lightweight optics; composite replica mirrors; active optics; space optics AB We report progress in the development of very lightweight (<5 kg/m(2)) mirrors made by replication using graphite fiber cyanate ester resin composites. The replication process is optimized to significantly improve the surface smoothness and figure quality. Achievements include near-diffraction-limited optical performance [<1/20 wave root mean square (rms) at 632.8 nm] in replica flats, fractional wave rms performance in curved mirrors at 90% pupil, and almost exact reproduction of the surface microroughness of the mandrel. The curved mirrors typically show some edge roll off and several waves (rms optical) of astigmatism, coma, and third-order spherical aberration. These are indications of thermal contraction in an inhomogeneous medium. The inhomogeneity is due to a systematic radial variation In density and fiber/ resin ratio induced in composite plies when draped around a small and highly curved mandrel. The figure accuracy is expected to improve with larger size optics and in mirrors with longer radii of curvature. Nevertheless, the present accuracy figure is sufficient for using postfiguring techniques such as ion milling to achieve diffraction-limited performance at optical and UV wavelengths. We demonstrate active figure control using a simple apparatus of low-mass, low-force actuators to correct astigmatism. The optimized replication technique is applied to the fabrication of a 0.6-m-diam mirror with an areal density of 3.2 kg/m(2). Our result demonstrates that the very lightweight, large-aperture construction used in radio telescopes can now be applied to optical telescopes. (C) 2000 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(00)03609-6]. C1 Composite Mirror Applicat Inc, Greenbelt, MD 20771 USA. Catholic Univ Amer, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Opt Branch, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Sigma Res Inc, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Composite Mirror Applicat Inc, Tucson, AZ 85710 USA. RP Chen, PC (reprint author), Composite Mirror Applicat Inc, Code 686-9, Greenbelt, MD 20771 USA. NR 11 TC 38 Z9 41 U1 1 U2 4 PU SPIE-INT SOCIETY OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98225 USA SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD SEP PY 2000 VL 39 IS 9 BP 2320 EP 2329 DI 10.1117/1.1288125 PG 10 WC Optics SC Optics GA 352KF UT WOS:000089213800002 ER PT J AU Kamanina, NV Vikhnin, VS Leyderman, A Barrientos, A Cui, Y Vlasse, M AF Kamanina, NV Vikhnin, VS Leyderman, A Barrientos, A Cui, Y Vlasse, M TI Effect of fullerenes C-60 and C-70 on the absorption spectrum of 2-cyclooctylamino-5-nitropyridine SO OPTICS AND SPECTROSCOPY LA English DT Article ID GLASSES AB The influence of fullerenes C-60 and C-70 On the absorption spectrum of 2-cyclooctylamino-5-nitropyridine (COANP) is studied. A substantial shift of the absorption band edge of COANP-C-70 to the IR region was observed, This effect was compared with the data obtained for COANP-C-60. The experimental results were explained using the model that takes into account the interaction between electronic subsystems of COANP and fullerene. (C) 2000 MAIK "Nauka/Interperiodica". C1 SI Vavilov State Opt Inst, All Russian Res Ctr, St Petersburg 199034, Russia. Russian Acad Sci, AF Ioffe Physicotech Inst, St Petersburg 199021, Russia. UPR RUM, Dept Phys, Mayaguez, PR 00680 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Kamanina, NV (reprint author), SI Vavilov State Opt Inst, All Russian Res Ctr, St Petersburg 199034, Russia. NR 7 TC 8 Z9 8 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0030-400X J9 OPT SPECTROSC+ JI Opt. Spectrosc. PD SEP PY 2000 VL 89 IS 3 BP 369 EP 371 DI 10.1134/1.1310701 PG 3 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 367HX UT WOS:000090056600010 ER PT J AU Kaminskii, AA McCray, CL Lee, HR Lee, SW Temple, DA Chyba, TH Marsh, WD Barnes, JC Annanenkov, AN Legun, VD Eichler, HJ Gad, GMA Ueda, K AF Kaminskii, AA McCray, CL Lee, HR Lee, SW Temple, DA Chyba, TH Marsh, WD Barnes, JC Annanenkov, AN Legun, VD Eichler, HJ Gad, GMA Ueda, K TI High efficiency nanosecond Raman lasers based on tetragonal PbWO4 crystals SO OPTICS COMMUNICATIONS LA English DT Article DE Raman scattering; PbWO4 tungstate; Stokes and anti-Stokes generation; lidar; lasers ID SCATTERING; KGD(WO4)(2); GENERATION; REGION AB We report on Laser action in linear and ring Raman oscillators based on novel chi((3))-active PbWO4 crystals with scheelite structure (omega(R) = 901 cm(-1)). These resonators are pumped by the fundamental and the second harmonic wavelengths, respectively, of a Q-switched Nd3+:Y3Al5O12 laser. In these preliminary measurements, conversion efficiencies as high as 20% are observed. To our knowledge, this is the first such demonstration of Raman lasing in lead tungstate in the nanosecond regime. Raman lasers based on PbWO4 are very promising for several applications, including the generation of wavelengths in the uv (in conjunction with other nonlinear processes) for ozone differential absorption lidar. This material has optical transparency from approximate to 0.33 to approximate to 5.5 mu m, making it also potentially useful for trace gas detection in the infrared. Furthermore, it has a high damage threshold and is not hydroscopic. Some new data on picosecond high-order Stokes and anti-Stokes generation are also presented. In particular, our SRS experiments with a 1-mu m Nd3+:Y3Al5O12 pump laser demonstrate multiple anti-Stokes emission up to the 10th component with lambda(ASt10) = 0.5433 mu m. (C) 2000 Published by Elsevier Science B.V. C1 Hampton Univ, Dept Phys, Res Ctr Opt Phys, Hampton, VA 23668 USA. Russian Acad Sci, Inst Crystallog, Moscow 117333, Russia. NASA, Langley Res Ctr, Laser Syst Branch, Hampton, VA 23681 USA. Bogorodytsk Techno Chem Plant, Bogorodytsk 301800, Russia. Tech Univ Berlin, Inst Opt, D-10623 Berlin, Germany. Univ Electrocommun, Inst Laser Sci, Chofu, Tokyo 1828585, Japan. RP Chyba, TH (reprint author), Hampton Univ, Dept Phys, Res Ctr Opt Phys, Hampton, VA 23668 USA. NR 36 TC 131 Z9 139 U1 1 U2 13 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0030-4018 J9 OPT COMMUN JI Opt. Commun. PD SEP 1 PY 2000 VL 183 IS 1-4 BP 277 EP 287 DI 10.1016/S0030-4018(00)00842-7 PG 11 WC Optics SC Optics GA 351JF UT WOS:000089153500031 ER PT J AU Gentry, BM Chen, HL Li, SX AF Gentry, BM Chen, HL Li, SX TI Wind measurements with 355-nm molecular Doppler lidar SO OPTICS LETTERS LA English DT Article ID EDGE TECHNIQUE; VALIDATION AB A Doppler lidar system based on the molecular double-edge technique is described. The system is mounted in a modified van to permit deployment in field operations. The lidar operates with a tripled Nd:YAG laser at 355 nm, a 45-cm-aperture telescope, and a matching azimuth-over-elevation scanner to permit full sky access. Validated atmospheric wind profiles were measured from 1.8 to 35 km with a 178-m vertical resolution. The range-dependent rms deviation of the horizontal wind speed is 0.4-6 m/s. The measured wind speed and direction are in good agreement with the rawinsonde wind measurements made simultaneously from the same location. (C) 2000 Optical Society of America OCIS codes: 010.3640, 120.2230, 010.7030, 120.0280. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Sci & Engn Serv Inc, Burtonsville, MD 20866 USA. Orbital Sci Corp, Greenbelt, MD 20770 USA. RP Gentry, BM (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Code 912, Greenbelt, MD 20771 USA. NR 11 TC 87 Z9 108 U1 3 U2 7 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD SEP 1 PY 2000 VL 25 IS 17 BP 1231 EP 1233 DI 10.1364/OL.25.001231 PG 3 WC Optics SC Optics GA 349KV UT WOS:000089045000003 PM 18066176 ER PT J AU Mancinelli, RL AF Mancinelli, RL TI Accessing the Martian deep subsurface to search for life SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 24th General Assembly of the European-Geophysical-Society CY APR 19-23, 1999 CL THE HAGUE, NETHERLANDS SP European Geophys Soc ID MARS; MICROORGANISMS; ORIGIN AB To date there have been no data indicating that the surface of Mars is inhabited. Research conducted on Earth has revealed that life can exist deep beneath the surface of a planet. Current data from Mars missions suggesting the presence of liquid water early in Mars' history and mathematical modeling of the fate of water on Mars imply that liquid water may exist deep beneath the surface of Mars. The existence of liquid water beneath the Martian surface, combined with life's ability to live chemolithoautotrophically, leads to the hypothesis that life may exist deep beneath the Martian surface. Acquisition and analyses of Martian subsurface samples will shed light on the possibility of extant or extinct life, in permafrost and liquid water, on Mars, the processes leading to the origin of life, and the size of the Solar System's habitable zone. The results of a workshop convened by NASA in 1998 suggest that no fewer than two missions could be considered for accessing the deep subsurface of Mars. This two mission scenario includes a mission penetrating to a depth of similar to 300 m and a mission penetrating to a depth of similar to 3 km. As in all space missions the power, mass and volume of the penetration system and all associated equipment to be used to gain access to the Martian subsurface must be kept to a minimum. One technique that may be applicable, but in need of further development, is an electrically heated probe (bit) that penetrates and cores by melting through rock. The probe is attached to an umbilical cable to provide power and to allow periodic retrieval of the probe. This approach appears to address planetary protection concerns and may decrease the mass, power and volume requirements of conventional drilling systems by eliminating the need for casing material, drilling fluids, and handling potentially contaminated debris from the bore hole. Deep drilling on Mars presents several planetary protection forward and back contamination issues. These issues include sample handling at the surface as well as upon return to Earth. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, SETI, Moffett Field, CA 94035 USA. RP Mancinelli, RL (reprint author), NASA, Ames Res Ctr, SETI, Mail Stop 239-12, Moffett Field, CA 94035 USA. RI Mancinelli, Rocco/L-8971-2016 NR 19 TC 19 Z9 19 U1 1 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 SEP PY 2000 VL 48 IS 11 BP 1035 EP 1042 DI 10.1016/S0032-0633(00)00077-5 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 372YD UT WOS:000165260900004 ER PT J AU Hofmann, BA Farmer, JD AF Hofmann, BA Farmer, JD TI Filamentous fabrics in low-temperature mineral assemblages: are they fossil biomarkers? Implications for the search for a subsurface fossil record on the early Earth and Mars SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 24th General Assembly of the European-Geophysical-Society CY APR 19-23, 1999 CL THE HAGUE, NETHERLANDS SP European Geophys Soc ID THERMAL-SPRING DEPOSITS; MICROBIAL ACTIVITY; DRUMMOND BASIN; BIOSPHERE; DEEP; PRECIPITATION; AUSTRALIA; LIFE; BACTERIA; PACIFIC AB The subsurface has been recognized as a possible habitat for microbial life on Mars. An analogous fossil record of subsurface life is nearly missing on Earth. Here we present evidence of the widespread occurrence of such a record: tubular filamentous structures with typical core diameters of 1-2 mum were found as inclusions in minerals deposited from low-T (<100C) aqueous fluids in subsurface environments at >140 localities worldwide. Filaments are frequently organized in composite structures with architectures similar to microbial mats. Filaments thickly encrusted by minerals exhibit gravity-oriented structures of macroscopic dimensions that are similar to stalactites. Environments of formation are sites of low-T water circulation in macroporous rocks such as volcanics, oxidized ores, limestone solution cavities and cavernous macrofossils. The age of occurrence ranges from Precambrian to Subrecent. We interpret the filamentous structures as permineralized and encrusted microbial filaments based on the following arguments: tubular construction of filaments with constant core diameters typical of microbes (1.5 +/- 1.1 mum), coalescence of filaments to form mat-like structures, gravity draping of micron-thin filaments indicating an originally flexible consistency, and restriction to low-T mineral assemblages. These filamentous structures formed in subsurface environments are similar in size, morphology and construction to fossilized microbes observed in modern terrestrial and marine thermal springs. This newly recognized fossil record of subterranean microbial life opens up new perspectives in the study of the paleobiology of the terrestrial subsurface and in the exploration for fossil life on Mars. Potential host rocks on Mars include major nonsedimentary units such as volcanics and impactites. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Museum Nat Hist, CH-3005 Bern, Switzerland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Hofmann, BA (reprint author), Museum Nat Hist, Bernastr 15, CH-3005 Bern, Switzerland. NR 65 TC 56 Z9 64 U1 1 U2 4 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 SEP PY 2000 VL 48 IS 11 BP 1077 EP + DI 10.1016/S0032-0633(00)00081-7 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 372YD UT WOS:000165260900008 ER PT J AU Kminek, G Bada, JL Botta, O Glavin, DP Grunthaner, F AF Kminek, G Bada, JL Botta, O Glavin, DP Grunthaner, F TI MOD: an organic detector for the future robotic exploration of Mars SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 24th General Assembly of the European-Geophysical-Society CY APR 19-23, 1999 CL THE HAGUE, NETHERLANDS SP European Geophys Soc ID AMINO-ACIDS; SEARCH; LIFE AB Searching for extinct or extant life on Mars is part of the future NASA surveyor class missions. Looking for key organic compounds that are essential for biochemistry as we know it or indicative of extraterrestrial organic influx is the primary goal of the Mars Organic Detector (MOD). MOD is able to detect amino acids, amines and PAHs with at least 100 times higher sensitivity than the Viking GCMS experiment. MOD is not capable of identifying specific organic molecules but can assess the organic inventory of amines and PAHs on the planet. MOD can also quantify adsorbed and chemisorbed water and evolved carbon dioxide in a stepped heating cycle to determine specific carbon-bearing minerals. All that comes with no sample preparation and no wet chemistry. The organics can be isolated from the carrier matrix by heating the sample and recovering the volatile organics on a cold finger. This sublimation technique can be used for extracting amino acids, amines and PAHs under Mars ambient conditions. The detection of amino acids, amines and PAHs is based on a fluorescence detection scheme. The MOD concept has functioned as a laboratory breadboard since 1998. A number of natural samples including shells, clays, bones, lambda -DNA and E.-coli bacteria have been used and organic molecules have been extracted successfully in each case. The first prototype of MOD is operational as of early fall of 1999. MOD has been selected for the definition phase of the NASA-MSR 2003 mission. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Scripps Inst Oceanog, La Jolla, CA 92093 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bada, JL (reprint author), Scripps Inst Oceanog, 9500 Gilman Dr, La Jolla, CA 92093 USA. RI Glavin, Daniel/D-6194-2012 OI Glavin, Daniel/0000-0001-7779-7765 NR 10 TC 25 Z9 26 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 SEP PY 2000 VL 48 IS 11 BP 1087 EP 1091 DI 10.1016/S0032-0633(00)00082-9 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 372YD UT WOS:000165260900009 ER PT J AU Mancinelli, RL Klovstad, M AF Mancinelli, RL Klovstad, M TI Martian soil and UV radiation: microbial viability assessment on spacecraft surfaces SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 24th General Assembly of the European-Geophysical-Society CY APR 19-23, 1999 CL THE HAGUE, NETHERLANDS SP European Geophys Soc ID MARS; ENVIRONMENT; SURVIVAL; SPORES AB Terrestrial microbes may reach the surface of Mars via inadequately sterilized spacecraft landers, revers, or through accidental impact of orbiters. This investigation was initiated to determine if Martian dust could protect spores of Bacillus subtilis on spacecraft surfaces from the UV radiation that falls onto the Martian surface. A monolayer of washed spores of Bacillus subtilis strain HA 101 was placed onto the surface of aluminum coupons and dried at 30 degreesC for 18 h. After drying dust prepared from sieved simulated Mars soil standard (Mars JSC-1 obtained from NASA Johnson Space Center, Houston, Texas, USA), or Fe-montmorillonite was placed on top of the spore monolayer of some of the coupons to a thickness of either 1 mm, 0.5 mm, 100 or 12 mum. The coupons were then exposed to UV radiation from a deuterium lamp (Oriel model 6316) and samples collected periodically to determine survival. The total number of surviving spores was determined using the most probable number (MPN) method. As a control, samples were prepared in triplicate as described above except that the coupons were not exposed to UV radiation. The data indicate that an unprotected monolayer of spores will be killed within minutes when exposed to the UV radiation flux falling onto the surface of Mars, but that if they are covered by either an additional layer of spores or a few microns of dust they will survive for long periods of time. This implies that spore-forming microbes on spacecraft surfaces can be protected by a thin layer of Mars dust and can potentially contaminate the planet. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Mancinelli, RL (reprint author), NASA, Ames Res Ctr, SETI Inst, Mail Stop 239-12, Moffett Field, CA 94035 USA. RI Mancinelli, Rocco/L-8971-2016 NR 25 TC 71 Z9 72 U1 2 U2 11 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 SEP PY 2000 VL 48 IS 11 BP 1093 EP 1097 DI 10.1016/S0032-0633(00)00083-0 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 372YD UT WOS:000165260900010 ER PT J AU Mileikowsky, C Cucinotta, FA Wilson, JW Gladman, B Horneck, G Lindegren, L Melosh, J Rickman, H Valtonen, M Zheng, JQ AF Mileikowsky, C Cucinotta, FA Wilson, JW Gladman, B Horneck, G Lindegren, L Melosh, J Rickman, H Valtonen, M Zheng, JQ TI Risks threatening viable transfer of microbes between bodies in our solar system SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 24th General Assembly of the European-Geophysical-Society CY APR 19-23, 1999 CL THE HAGUE, NETHERLANDS SP European Geophys Soc ID DEINOCOCCUS-RADIODURANS; BACILLUS-SUBTILIS; SPORES; LIFE; METEORITES; RESPONSES; REPAIR; ORIGIN; EARTH; MARS AB A fraction of the number of ejecta expelled from a planet by comet or asteroid impacts end up landing on another planet. If microorganisms were living in the ground before impact, they would be transported inside ejecta to the target planet. During that perilous trip, they would be subject to four main categories of threat to their survival: dynamical stress, excess temperature, radiation, chemical attack and vacuum. The effect of these, in the form of survival fractions as a function of time, as well as approximate numbers of arriving ejecta with viable flight times, have been investigated in a quantitative study we have made. The result shows that viable transfer from Mars to Earth and vice versa was highly probable during the first 0.5 Ga, and also probable, but with lower frequency, thereafter. Here we follow up with considerations about the consequences of the result regarding the question of whether the ancestor cell of all life on Earth must have originated on Earth, or whether it could have originated on Mars, its descendants thereafter moving to Earth. Some other possible consequences are also discussed. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 KTH Royal Inst Technol, Stockholm, Sweden. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NASA, Langley Space Res Ctr, Newport News, VA USA. Observ Cote Azur, F-06003 Nice, France. DLR, Cologne, Germany. Univ Lund, Lund Observ, S-22100 Lund, Sweden. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Univ Turku, Observ, SF-20500 Turku, Finland. Univ Uppsala, Astron Observ, S-75105 Uppsala, Sweden. RP Mileikowsky, C (reprint author), KTH Royal Inst Technol, Stockholm, Sweden. NR 27 TC 23 Z9 24 U1 0 U2 4 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 SEP PY 2000 VL 48 IS 11 BP 1107 EP 1115 DI 10.1016/S0032-0633(00)00085-4 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 372YD UT WOS:000165260900012 ER PT J AU Teplitz, HI Malumuth, E Woodgate, BE Moseley, SH Gardner, JP Kimble, RA Bowers, CW Kutyrev, AS Fettig, RK Wesenberg, RP Mentzell, EE AF Teplitz, HI Malumuth, E Woodgate, BE Moseley, SH Gardner, JP Kimble, RA Bowers, CW Kutyrev, AS Fettig, RK Wesenberg, RP Mentzell, EE TI Redshift estimation from low-resolution prism spectral energy distributions with a Next Generation Space Telescope multiobject spectrograph SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID HUBBLE DEEP FIELD; GALAXIES; PERFORMANCE; UNIVERSE; COLORS AB We discuss the utility of a low-resolution prism as a component of a multiobject spectrometer for NASA's proposed Next Generation Space Telescope (NGST). Low-resolution prism spectroscopy permits simultaneous observation of the 0.6-5 mu m wavelength regime at R less than or similar to 50. Such data can take advantage of modern techniques in spectral energy distribution (SED) fitting to determine source redshifts, sometimes called "photometric redshifts." We compare simulated prism observations with filter imaging for this purpose with NGST. Low-resolution prism observations of galaxy SEDs provide a significant advantage over multifilter observations for any realistic observing strategy. For an ideal prism in sky background-limited observing, the prism has a signal-to-noise ratio advantage of the square root of the resolution over serial observations by filters with similar spatial and spectral resolution in equal integration time. For a realistic case the advantage is slightly less, and we have performed extensive simulations to quantify it. We define strict criteria for the recovery of input redshifts, such that to be considered a success, redshift residuals must be delta(z) < 0.03 + 0.1 log z. The simulations suggest that in 10(5) s, a realistic prism will recover (by our definition of success) the redshift of similar to 70% of measured objects (subject to multiobject spectrograph selection) at K(AB) < 32, compared to less than 45% of the objects with serial filter observations. The advantage of the prism is larger in the regime of faint (K(AB) > 30) objects at high redshift (z > 4), where the prism recovers 80% of redshifts, while the filters recover barely 35% to similar accuracy. The primary discovery space of NGST will be at the faintest magnitudes and the highest redshifts. Many important objects will be too faint for follow-up at higher spectral resolution, so prism observations are the optimal technique to study them. Prism observations also reduce the contamination of high-redshift samples by lower redshift interlopers. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Raytheon ITSS Corp, Lanham, MD 20706 USA. Moscow MV Lomonosov State Univ, Sternberg Astron Inst, Moscow, Russia. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, STAAC, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Instrument Technol Ctr, Greenbelt, MD 20771 USA. RP Teplitz, HI (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. EM hit@binary.gsfc.nasa.gov RI Woodgate, Bruce/D-2970-2012 NR 37 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD SEP PY 2000 VL 112 IS 775 BP 1188 EP 1199 DI 10.1086/316619 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356BR UT WOS:000089424600005 ER PT J AU Hildebrand, RH Davidson, JA Dotson, JL Dowell, CD Novak, G Vaillancourt, JE AF Hildebrand, RH Davidson, JA Dotson, JL Dowell, CD Novak, G Vaillancourt, JE TI A primer on far-infrared polarimetry SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID GALACTIC MAGNETIC-FIELD; STAR-FORMING REGIONS; SUBMILLIMETER POLARIZATION; GRAIN ALIGNMENT; CIRCULAR-POLARIZATION; AMBIPOLAR DIFFUSION; LINEAR-POLARIZATION; OPTICAL-PROPERTIES; ARRAY POLARIMETRY; MOLECULAR CLOUDS AB We present an introduction to observing procedures and principles of analysis used in far-infrared polarimetry. The observing procedures are those for single-dish observations of thermal emission from aligned dust grains. We discuss techniques for removing backgrounds and for reducing and evaluating errors. The principles of analysis are those required for interpreting polarization maps and polarization spectra in terms of opacity, field structure, and variations in temperature and polarizing efficiency. C1 Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Dept Phys, Chicago, IL 60637 USA. NASA, Ames Res Ctr, Univ Space Res Assoc, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, SETI, Moffett Field, CA 94035 USA. CALTECH, Pasadena, CA 91125 USA. Northwestern Univ, Dearborn Observ, Dept Phys & Astron, Evanston, IL 60208 USA. RP Hildebrand, RH (reprint author), Univ Chicago, Enrico Fermi Inst, 5640 S Ellis Ave, Chicago, IL 60637 USA. OI Vaillancourt, John/0000-0001-8916-1828 NR 73 TC 111 Z9 112 U1 0 U2 1 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD SEP PY 2000 VL 112 IS 775 BP 1215 EP 1235 DI 10.1086/316613 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356BR UT WOS:000089424600008 ER PT J AU Walborn, NR Lennon, DJ Heap, SR Lindler, DJ Smith, LJ Evans, CIJ Parker, JW AF Walborn, NR Lennon, DJ Heap, SR Lindler, DJ Smith, LJ Evans, CIJ Parker, JW TI The ultraviolet and optical spectra of metal-deficient O stars in the Small Magellanic Cloud SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID B-SUPERGIANTS; CLASSIFICATION; POPULATIONS; PARAMETERS; 30-DORADUS; GALAXIES; CLUSTER; NGC-346 AB An ultraviolet and optical spectral atlas of 15 O stars in the Small Magellanic Cloud (SMC) is presented and described. The echelle data have resolving powers of order 10(4); they were obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph in the UV, and at the Anglo-Australian Telescope or the European Southern Observatory 3.6 m in the optical. The ultimate objective is to develop metal-deficient templates for the interpretation of distant starbursts, but here we discuss interesting new properties of the SMC stars themselves, revealed by the high quality of these data. The SMC metal deficiency produces anomalously weak stellar-wind profiles along the entire O main sequence, as well as at intermediate luminosities; the first intermediate Si IV lambda 1400 wind profile in the SMC is shown. The second known Of star in the SMC displays wind peculiarities that are identical to those of its spectral classmate, again likely due to the low systemic metallicity. Several objects display mark:ed CNO anomalies, including the first cases of C III lambda 4650 emission without N III lambda 4640 in O-type spectra. The N/C ratio appears to increase with mass, extent of evolution away from the zero-age main sequence, and/or rotational velocity in the young cluster NGC 346. In addition, the first examples of Onfp (Oef) and Of?p spectra in the SMC have been found (the latter being only the fourth member of its peculiar shell category known anywhere). The UV wind characteristics of these objects correlate with their optical peculiarities. Ail these spectroscopic phenomena provide diagnostics of the evolutionary status of metal-deficient massive stars. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Isaac Newton Grp, Santa Cruz De La Palma 38700, Spain. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. UCL, Dept Phys & Astron, London WC1E 6BT, England. SW Res Inst, Boulder, CO 80302 USA. RP Walborn, NR (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. EM walborn@stsci.edu; djl@ing.iac.es; heap@srh.gsfc.nasa.gov; lindler@rockit.gsfc.nasa.gov; ljs@star.ucl.ac.uk; cje@star.ucl.ac.uk; joel@boulder.swri.edu NR 42 TC 93 Z9 93 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD SEP PY 2000 VL 112 IS 775 BP 1243 EP 1261 DI 10.1086/316617 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 356BR UT WOS:000089424600010 ER PT J AU Sandmeier, SR AF Sandmeier, SR TI Acquisition of bidirectional reflectance factor data with field goniometers SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID HYPERSPECTRAL BRDF DATA; CANOPY REFLECTANCE; VEGETATION INDEXES; OPTICAL DEPTH; RADIOMETER; INSTRUMENT; ERRORS; PANELS; CALIBRATION; SENSITIVITY AB With the launch of new spaceborne sensors capable of acquiring bidirectional reflectance distribution function (BRDF) data of the earth surface, extensive ground BRDF measurements will become necessary to provide much-needed ground reference data from numerous remote sensing applications. To obtain homologous BRDF data from field goniometer devices, guidelines and recommendations are required that will allow a better comparison between BRDF data from different goniometer systems, from air- and spaceborne sensors, as well as form theoretical studies with physically based BRDF models. In this study, tow examples of recent goniometer systems are given, and the quality and limits of field goniometer systems are discussed, along with detailed practical advice for the acquisition, processing, and documentation of BRDF data and ancillary information. Special emphasis is on the characterization and documentation of atmospheric and measurement surface conditions. The study also presents common shortcomings and limitations of field BRDF data, such as the influence of diffuse irradiance and changes in illumination conditions, and gives recommendations for correcting these effects from an application-oriented viewpoint. (C)Elsevier Science Inc., 2000. C1 NASA, Goddard Space Flight Ctr, USRA, Biospher Sci Branch, Greenbelt, MD 20771 USA. RP Sandmeier, SR (reprint author), NASA, Goddard Space Flight Ctr, USRA, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. NR 45 TC 47 Z9 52 U1 4 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 SEP PY 2000 VL 73 IS 3 BP 257 EP 269 DI 10.1016/S0034-4257(00)00102-4 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 347GH UT WOS:000088919500001 ER PT J AU Smirnov, A Holben, BN Eck, TF Dubovik, O Slutsker, I AF Smirnov, A Holben, BN Eck, TF Dubovik, O Slutsker, I TI Cloud-screening and quality control algorithms for the AERONET database SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID AEROSOLS; EXTINCTION AB Automatic globally distributed networks for monitoring aerosol optical depth provide measurements of natural and anthropogenic aerosol loading, which is important in many local and regional studies as well as global change research investigations. The strength of such networks relies on imposing a standardization of measurement and processing, allowing multiyear and large-scale comparisons. The development of the Aerosol Robotic Network (AERONET) for systematic ground-based sunphotometer measurements of aerosol optical depth is an essential and evolving step in this process. The growing database requires the development of a consistent, reproducible, and system-wide cloud-screening procedure. This paper discusses the methodology and justification of the cloud-screening algorithm developed for the AERONET database. The procedure has been comprehensively tested on experimental data obtained in different geographical and optical conditions. These conditions include biomass burning events in Brazil and Zambia, hazy summer conditions in the Washington DC area, clean air advected from the Canadian Arctic, and variable cloudy conditions. For various sites our screening algorithm eliminates from similar to 20% to 50% of the initial data depending on cloud conditions. Certain shortcomings of the proposed procedure are discussed. (C) Elsevier Science Inc., 2000. C1 NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. Raytheon ITSS, Lanham, MD USA. RP Smirnov, A (reprint author), NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. 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 17 TC 715 Z9 758 U1 9 U2 40 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 SEP PY 2000 VL 73 IS 3 BP 337 EP 349 DI 10.1016/S0034-4257(00)00109-7 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 347GH UT WOS:000088919500007 ER PT J AU Sterling, AC AF Sterling, AC TI Solar spicules: A review of recent models and targets for future observations - (Invited review) SO SOLAR PHYSICS LA English DT Review ID X-RAY JETS; H-ALPHA-SURGES; MAGNETIC-FLUX TUBES; DAMPED ALFVEN WAVES; CHROMOSPHERIC FINE-STRUCTURE; CORONAL HEATING MECHANISMS; LOWER TRANSITION REGION; REBOUND SHOCK MODEL; NUMERICAL SIMULATIONS; BRIGHT POINTS AB Since their discovery over 100 years ago, there have been many suggestions for the origin and development of solar spicules. Because the velocities of spicules are comparable to the sound and Alfven speeds of the low chromosphere, linear theory cannot fully describe them. Consequently, detailed tests of theoretical ideas had to await the development of computing power that only became available during the 1970s. This work reviews theories for spicules and spicule-like features over approximately the past 25 years, with an emphasis on the models based on nonlinear numerical simulations. These models have given us physical insight into wave propagation in the solar atmosphere, and have helped elucidate how such waves, and associated shock waves, may be capable of creating motions and structures on magnetic flux tubes in the lower solar atmosphere. So far, however, it has been difficult to reproduce the most-commonly-quoted parameters for spicules with these models, using what appears to be the most suitable input parameters. A key impediment to developing satisfactory models has been the lack of reliable observational information, which is a consequence of the small angular size and transient lifetime of spicules. I close with a list of key observational questions to be addressed with space-based satellites, such as the currently operating TRACE satellite, and especially the upcoming Solar-B mission. Answers to these questions will help determine which, if any, of the current models correctly explains spicules. C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci SD50, Huntsville, AL 35812 USA. RP Sterling, AC (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci SD50, Huntsville, AL 35812 USA. NR 168 TC 163 Z9 167 U1 2 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD SEP PY 2000 VL 196 IS 1 BP 79 EP 111 DI 10.1023/A:1005213923962 PG 33 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369VW UT WOS:000165089300007 ER PT J AU Satava, R Angood, PB Harnett, B Macedonia, C Merrell, R AF Satava, R Angood, PB Harnett, B Macedonia, C Merrell, R TI The physiologic cipher at altitude: Telemedicine and real-time monitoring of climbers on Mount Everest SO TELEMEDICINE JOURNAL AND E-HEALTH LA English DT Article ID WEARABLE SYSTEM; SENSOR; GLUCOSE; DEVICE AB Advanced wearable biosensors for vital-signs monitoring (physiologic cipher) are available to improve quality of healthcare in hospital, nursing home, and remote environments. The objective of this study was to determine reliability of vital-signs monitoring systems in extreme environments. Three climbers were monitored 24 hours while climbing through Khumbu Icefall. Data were transmitted to Everest Base Camp (elevation 17,800 feet) and retransmitted to Yale University via telemedicine. Main outcome measures (location, heart rate, skin temperature, core body temperature, and activity level) all correlated through time-stamped identification. Two of three location devices functioned 100% of the time, and one device failed after initial acquisition of location 75% of the time. Vital-signs monitors functioned from 95%-100% of the time, with the exception of one climber whose heart-rate monitor functioned 78% of the time. Due to architecture of automatic polling and data acquisition of biosensors, no climber was ever without a full set of data for more than 25 minutes. Climbers were monitored continuously in real-time from Mount Everest to Yale University for more than 45 minutes. Heart rate varied from 76 to 164 beats per minute, skin temperature varied from 5 to 10 degreesC, and core body temperature varied only 1-3 degreesC. No direct correlation was observed among heart rate, activity level, and body temperature, though numerous periods suggested intense and arduous activity. Field testing in the extreme environment of Mount Everest demonstrated an ability to track in real time both vital signs and position of climbers. However, these systems must be more reliable and robust. As technology transitions to commercial products, benefits of remote monitoring will become available for routine healthcare purposes. C1 Yale Univ, Sch Med, Dept Surg, New Haven, CT 06510 USA. Virginia Commonwealth Univ, Med Coll Virginia, NASA, Commercial Space Ctr Med Informat & Technol Appli, Richmond, VA 23298 USA. Uniformed Serv Univ Hlth Sci, Dept Obstet & Gynecol, Bethesda, MD 20814 USA. RP Satava, R (reprint author), Yale Univ, Sch Med, Dept Surg, 40 Temple St,Suite 3-A, New Haven, CT 06510 USA. NR 14 TC 37 Z9 37 U1 1 U2 4 PU MARY ANN LIEBERT INC PUBL PI LARCHMONT PA 2 MADISON AVENUE, LARCHMONT, NY 10538 USA SN 1530-5627 J9 TELEMED J E-HEALTH JI Telemed. J. e-Health PD FAL PY 2000 VL 6 IS 3 BP 303 EP 313 DI 10.1089/153056200750040165 PG 11 WC Health Care Sciences & Services SC Health Care Sciences & Services GA 390LM UT WOS:000166296600002 PM 11110634 ER PT J AU Reid, RP Visscher, PT Decho, AW Stolz, JF Bebout, BM Dupraz, C Macintyre, LG Paerl, HW Pinckney, JL Prufert-Bebout, L Steppe, TF DesMarais, DJ AF Reid, RP Visscher, PT Decho, AW Stolz, JF Bebout, BM Dupraz, C Macintyre, LG Paerl, HW Pinckney, JL Prufert-Bebout, L Steppe, TF DesMarais, DJ TI The role of microbes in accretion, lamination and early lithification of modern marine stromatolites SO NATURE LA English DT Article ID SUBTIDAL STROMATOLITES; EXUMA-CAYS; BAHAMAS; MATS; COMMUNITIES AB For three billion years, before the Cambrian diversification of life, laminated carbonate build-ups called stromatolites were widespread in shallow marine seas(1,2). These ancient structures are generally thought to be microbial in origin and potentially preserve evidence of the Earth's earliest biosphere(1-3). Despite their evolutionary significance, little is known about stromatolite formation, especially the relative roles of microbial and environmental factors in stromatolite accretion(1,3). Here we show that growth of modern marine stromatolites represents a dynamic balance between sedimentation and intermittent lithification of cyanobacterial mats. Periods of rapid sediment accretion, during which stromatolite surfaces are dominated by pioneer communities of gliding filamentous cyanobacteria, alternate with hiatal intervals. These discontinuities in sedimentation are characterized by development of surface films of exopolymer and subsequent heterotrophic bacterial decomposition, forming thin crusts of microcrystalline carbonate. During prolonged hiatal periods, climax communities develop, which include endolithic coccoid cyanobacteria. These coccoids modify the sediment, forming thicker lithified laminae. Preservation of lithified layers at depth creates millimetre-scale lamination. This simple model of modern marine stromatolite growth may be applicable to ancient stromatolites. C1 Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, MGG, Miami, FL 33149 USA. Univ Connecticut, Dept Marine Sci, Groton, CT 06340 USA. Univ S Carolina, Sch Publ Hlth, Columbia, SC 29208 USA. Duquesne Univ, Dept Biol Sci, Pittsburgh, PA 15282 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Smithsonian Inst, Natl Museum Nat Hist, Washington, DC 20560 USA. Univ N Carolina, Inst Marine Sci, Morehead City, NC 28557 USA. Texas A&M Univ, Dept Oceanog, College Stn, TX 77843 USA. RP Reid, RP (reprint author), Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, MGG, 4600 Rickenbacker Causeway, Miami, FL 33149 USA. OI Visscher, Pieter/0000-0001-6911-1532 NR 30 TC 390 Z9 432 U1 10 U2 100 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD AUG 31 PY 2000 VL 406 IS 6799 BP 989 EP 992 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 348ZW UT WOS:000089020200043 PM 10984051 ER PT J AU Diskin, B Thomas, JL AF Diskin, B Thomas, JL TI Half-space analysis of the defect-correction method for Fromm discretization of convection SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE half-space analysis; convection equation; Fromm discretization; defect-correction method ID FLOWS AB A novel, comprehensive, discrete, half-space analysis for the defect-correction method has been developed. This analysis plays the same role for nonelliptic-problem solvers as the full-space Fourier mode analysis plays for elliptic-problem solvers. Numerical simulations con rm the accuracy of the half-space analysis. The following important findings about the defect-correction method applied to the Fromm discretization of the two-dimensional convection equation are reported: 1. The initial convergence rate of the defect-correction method is principally a function of the relative accuracy of the operators involved in the defect-correction iterations. 2. The asymptotic convergence rate is about 0.5 per defect-correction iteration. 3. If the driver operator is first-order accurate, then the initial convergence rates may be slow. The number of iterations required to get into the asymptotic convergence regime or/and to converge the algebraic error below the discretization-error level can be proportional to h(1/3). This h-dependent delay is a multidimensional phenomenon it cannot be observed in one-dimensional problems, and it disappears in the case of close alignment between the grid and the convection equation characteristic. 4. If the driver operator is second-order accurate, the defect-correction solver demonstrates the asymptotic convergence rate from the very beginning. Only one defect-correction iteration is required to converge algebraic error substantially below the discretization-error level. C1 NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Mail Stop 132C, Hampton, VA 23681 USA. EM bdiskin@icase.edu; j.l.thomas@larc.nasa.gov NR 20 TC 5 Z9 5 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 1064-8275 EI 1095-7197 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD AUG 31 PY 2000 VL 22 IS 2 BP 633 EP 655 DI 10.1137/S1064827599358637 PG 23 WC Mathematics, Applied SC Mathematics GA 349VA UT WOS:000089065200013 ER PT J AU Hansen, J Sato, M Ruedy, R Lacis, A Oinas, V AF Hansen, J Sato, M Ruedy, R Lacis, A Oinas, V TI Global warming in the twenty-first century: An alternative scenario SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article DE climate change; greenhouse gases; aerosols; air pollution ID CLIMATE-CHANGE; ATMOSPHERIC METHANE; KYOTO PROTOCOL; AEROSOLS; GROWTH; OZONE; SENSITIVITY; EMISSIONS; CHEMISTRY; FORCINGS AB A common view is that the current global warming rate will continue or accelerate, But we argue that rapid warming in recent decades has been driven mainly by non-CO2 greenhouse gases (GHGs), such as chlorofluorocarbons, CH4. and N2O, not by the products of fossil fuel burning, CO2 and aerosols, the positive and negative climate forcings of which are partially offsetting. The growth rate of non-CO2 GHGs has declined in the past decade. If sources of CH4 and O-3 precursors were reduced in the future, the change in climate forcing by non-CO2 GHGs in the next 50 years could be near zero. Combined with a reduction of black carbon emissions and plausible success in slowing CO2 emissions, this reduction of non-CO2 GHGs could lead to a decline in the rate of global warming, reducing the danger of dramatic climate change. Such a focus on air pollution has practical benefits that unite the interests of developed and developing countries. However, assessment of ongoing and future climate change requires composition-specific long-term global monitoring of aerosol properties. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Earth Inst, Ctr Climate Syst Res, New York, NY 10025 USA. Rutgers State Univ, Ctr Environm Predict, New York, NY 10025 USA. RP Hansen, J (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Lacis, Andrew/D-4658-2012 NR 70 TC 469 Z9 492 U1 24 U2 179 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD AUG 29 PY 2000 VL 97 IS 18 BP 9875 EP 9880 DI 10.1073/pnas.170278997 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 349WA UT WOS:000089067500014 PM 10944197 ER PT J AU Liao, XZ Zou, J Cockayne, DJH Jiang, ZM Wang, X Leon, R AF Liao, XZ Zou, J Cockayne, DJH Jiang, ZM Wang, X Leon, R TI Composition and its impact on shape evolution in dislocated Ge(Si)/Si islands SO APPLIED PHYSICS LETTERS LA English DT Article ID QUANTUM DOTS; GE ISLANDS; SI(001); GROWTH; TRANSITION; COHERENT; RELAXATION; PYRAMIDS; DOMES AB The composition distribution of Ge(Si)/Si (001) islands grown at 700 degrees C by molecular beam epitaxy is investigated using high-spatial resolution x-ray energy dispersive spectrometry in a scanning transmission electron microscope. Island shapes are investigated using cross-section transmission electron microscopy. Results show nonuniformity of the composition distribution in the islands, which affects the evolution of the aspect ratios of height-to-base diameter of dislocated islands. (C) 2000 American Institute of Physics. [S0003-6951(00)05235-9]. C1 Univ Sydney, Australian Key Ctr Microscopy & Microanal, Sydney, NSW 2006, Australia. Univ Oxford, Dept Mat, Oxford OX1 3PH, England. Fudan Univ, Surface Phys Lab, Shanghai 200433, Peoples R China. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Liao, XZ (reprint author), Univ Sydney, Australian Key Ctr Microscopy & Microanal, Sydney, NSW 2006, Australia. RI Liao, Xiaozhou/B-3168-2009; Zou, Jin/B-3183-2009 OI Liao, Xiaozhou/0000-0001-8565-1758; Zou, Jin/0000-0001-9435-8043 NR 19 TC 66 Z9 67 U1 1 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD AUG 28 PY 2000 VL 77 IS 9 BP 1304 EP 1306 DI 10.1063/1.1290384 PG 3 WC Physics, Applied SC Physics GA 346ZC UT WOS:000088900900022 ER PT J AU Lewis, MS AF Lewis, MS TI Watches all of aviation SO AVIATION WEEK & SPACE TECHNOLOGY LA English DT Letter C1 NASA, Langley Res Ctr, Aviat Safety Program, Hampton, VA 23665 USA. RP Lewis, MS (reprint author), NASA, Langley Res Ctr, Aviat Safety Program, Hampton, VA 23665 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MCGRAW HILL INC PI NEW YORK PA 1221 AVENUE OF THE AMERICAS, NEW YORK, NY 10020 USA SN 0005-2175 J9 AVIAT WEEK SPACE TEC JI Aviat. Week Space Technol. PD AUG 28 PY 2000 VL 153 IS 9 BP 9 EP 9 PG 1 WC Engineering, Aerospace SC Engineering GA 348TM UT WOS:000089002600004 ER PT J AU Bridges, N AF Bridges, N TI Fewer progress flights SO AVIATION WEEK & SPACE TECHNOLOGY LA English DT Letter C1 Jet Propuls Lab, Pasadena, CA 91109 USA. RP Bridges, N (reprint author), Jet Propuls Lab, Pasadena, CA 91109 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MCGRAW HILL INC PI NEW YORK PA 1221 AVENUE OF THE AMERICAS, NEW YORK, NY 10020 USA SN 0005-2175 J9 AVIAT WEEK SPACE TEC JI Aviat. Week Space Technol. PD AUG 28 PY 2000 VL 153 IS 9 BP 12 EP 12 PG 1 WC Engineering, Aerospace SC Engineering GA 348TM UT WOS:000089002600014 ER PT J AU Jozsa, R Abrams, DS Dowling, JP Williams, CP AF Jozsa, R Abrams, DS Dowling, JP Williams, CP TI Quantum clock synchronization based on shared prior entanglement SO PHYSICAL REVIEW LETTERS LA English DT Article AB We demonstrate that two spatially separated parties (Alice and Bob) can utilize shared prior quantum entanglement, and classical communications, to establish a synchronized pair of atomic clocks. In contrast to classical synchronization schemes, the accuracy of our protocol is independent of Alice's or Bob's knowledge of their relative locations or of the properties of the intervening medium. C1 Univ Bristol, Dept Comp Sci, Bristol BS8 1UB, Avon, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jozsa, R (reprint author), Univ Bristol, Dept Comp Sci, Venturers Bldg,Woodland Rd, Bristol BS8 1UB, Avon, England. RI DOWLING, JONATHAN/L-2749-2013 NR 14 TC 122 Z9 125 U1 2 U2 5 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD AUG 28 PY 2000 VL 85 IS 9 BP 2010 EP 2013 DI 10.1103/PhysRevLett.85.2010 PG 4 WC Physics, Multidisciplinary SC Physics GA 348BW UT WOS:000088965300058 ER PT J AU Toon, OB Tabazadeh, A Browell, EV Jordan, J AF Toon, OB Tabazadeh, A Browell, EV Jordan, J TI Analysis of lidar observations of Arctic polar stratospheric clouds during January 1989 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NITRIC-ACID TRIHYDRATE; SOUNDER HNO3 OBSERVATIONS; SULFURIC-ACID; SULFATE AEROSOLS; AIRBORNE LIDAR; PHYSICAL STATE; BALLOON OBSERVATIONS; REFRACTIVE-INDEXES; SIZE DISTRIBUTIONS; VOLCANIC AEROSOLS AB We present analyses of lidar backscatter and depolarization ratios for polar stratospheric clouds (PSCs) observed during the 1989 Airborne Arctic Stratospheric Experiment. The backscatter and depolarization ratios are available at one visible and one infrared wavelength. Water ice PSCs were identified at low ambient temperatures based upon their relatively large backscattering and depolarization ratios. The remaining clouds fall into four major categories. First, we observe a class of clouds that are not depolarizing at either of the two wavelengths. These clouds are identified as Type 1b PSCs, which are assumed to be composed of ternary solutions of H2SO4/HNO3/H2O. Type 1b clouds were never dominant, though on some dates they accounted for 25 to 40% of the observations. We find from the wavelength dependence of the backscattering by these clouds that their size distributions must be very narrow. Other optical observations of these clouds should consider the possible impact of these narrow size distributions on their data analysis. These clouds have a relatively large total particulate mass that is comparable to the known gas phase reservoir of nitric acid. The number density of Type 1b particles is similar to the concentrations of the ambient sulfate aerosols. The second category of clouds is highly depolarizing at both lidar wavelengths, but has relatively low backscattering ratios. We identify these clouds as Type 1a PSCs (assumed to be nitric acid tri- or dihydrate) which form only on a small subset by number, approximately 1% or less, of the ambient sulfate aerosols. These clouds were the first to be observed, and were especially common on the first few flights. They accounted for more than 70% of the observations on three flights. Type 1a particles are near 1 mu m or larger in radius. The third type of cloud is depolarizing at visible wavelengths, but not at near infrared wavelengths. These clouds were seen during portions of nearly every flight and comprised 10 to 25% of all of the observations. These clouds, which we refer to as Type 1c, are composed of small, solid particles. These clouds contain a relatively large mass of material, comparable to the gas phase reservoir of nitric acid. Type 1c particles are a few tenths of a micrometer in radius and have a concentration that is similar to that of the ambient sulfate aerosols. The final class of clouds has no depolarization at the lidar's visible wavelength but has significant depolarization at the infrared wavelength. Such particles were seen on many of the flights and sometimes accounted for as much as 30% of all the observations. We interpret these clouds as being mixtures of Type la and Ib PSCs. Although some polar stratospheric clouds have fairly homogeneous properties over very large spatial scales, many have variable properties at relatively small scales. Thus the various types of particles are often observed within a single cloud. Homogeneous clouds, composed only of solid particles seem inconsistent with a wave cloud origin. However, clouds in which several types of particles occur together may represent situations in which mountain waves have triggered solid particle formation. Alternatively, clouds composed of different types of particles may be in the process of freezing. We observed in regions upwind of the coldest temperatures that the air often did not contain clouds but may have had large supersaturations with respect to NAT. In contrast, regions downwind of the coldest temperatures often contained large solid particles in air that may have been close to NAT supersaturation. The correlation between PSC types and their respective temperature histories suggest that, given enough time, liquid particles will convert to solids. C1 Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80309 USA. Univ Colorado, Program Atmospher & Ocean Sci, Boulder, CO 80309 USA. NASA, Ames Res Ctr, Earth Syst Sci Div, Moffett Field, CA 94035 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. NASA, Ames Res Ctr, SAIC, Moffett Field, CA 94035 USA. RP Toon, OB (reprint author), Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA. EM toon@lasp.colorado.edu NR 79 TC 73 Z9 73 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 AUG 27 PY 2000 VL 105 IS D16 BP 20589 EP 20615 DI 10.1029/2000JD900144 PG 27 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 350NH UT WOS:000089107600012 ER PT J AU Hsu, NC Herman, JR Weaver, C AF Hsu, NC Herman, JR Weaver, C TI Determination of radiative forcing of Saharan dust using combined TOMS and ERBE data SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OPTICAL-THICKNESS; MINERAL AEROSOLS; SATELLITE; CLIMATE; WAVELENGTHS; BUDGET; SUN AB We determine the direct radiative forcing of Saharan dust aerosols by combining aerosol information derived from Nimbus-7 TOMS with radiation measurements observed at the top of atmosphere (TOA) by NOAA-9 ERBE made during February-July 1985. Cloud parameters and precipitable water derived from NOAA-9 HIRS2 were used to aid in screening for clouds and water vapor in the analyses. Our results indicate that under "cloud-free" and "dry" conditions there is a good correlation between the ERBE TOA outgoing longwave fluxes and the TOMS aerosol index measurements over both land and ocean in areas under the influence of airborne Saharan dust. The ERBE TOA outgoing shortwave fluxes were also found to correlate well with the dust loading derived from TOMS over ocean. However, the calculated shortwave forcing of Saharan dust aerosols is very weak and noisy over land for the range of solar zenith angle viewed by the NOAA-9 ERBE in 1985. Sensitivity factors of the TOA outgoing fluxes to changes in aerosol index were estimated using a linear regression fit to the ERBE and TOMS measurements. The ratio of the shortwave-to-longwave response to changes in dust loading over the ocean is found to be roughly 2 to 3 but opposite in sign. The monthly averaged "clear-sky" TOA direct forcing of airborne Saharan dust was also calculated by multiplying these sensitivity factors by the TOMS monthly averaged "clear-sky" aerosol index. Both the observational and theoretical analyses indicate that the underlying surface properties, dust layer height, ambient moisture content, and the presence of cloud all play important roles in determining the TOA direct radiative forcing due to mineral aerosols. C1 Raytheon ITSS, Lanham, MD USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SM & A Corp, Arlington, VA USA. RP Hsu, NC (reprint author), Sci Syst & Applicat Inc, Lanham, MD USA. EM hsu@wrabbit.gsfc.nasa.gov RI Hsu, N. Christina/H-3420-2013 NR 26 TC 69 Z9 69 U1 0 U2 3 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 AUG 27 PY 2000 VL 105 IS D16 BP 20649 EP 20661 DI 10.1029/2000JD900150 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 350NH UT WOS:000089107600015 ER PT J AU Dubovik, O King, MD AF Dubovik, O King, MD TI A flexible inversion algorithm for retrieval of aerosol optical properties from Sun and sky radiance measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SINGLE-SCATTERING ALBEDO; SIZE DISTRIBUTIONS; REFRACTIVE-INDEX; PHASE FUNCTION; ABSORPTION; EXTINCTION; PARTICLES; AUREOLE; OCEAN; RADIATION AB The problem of deriving a complete set of aerosol optical properties from Sun and sky radiance measurements is discussed. Algorithm development is focused on improving aerosol retrievals by means of including a detailed statistical optimization of the influence of noise in the inversion procedure. The methodological aspects of such an optimization are discussed in detail and revised according to both modern findings in inversion theory and practical experience in remote sensing. Accordingly, the proposed inversion algorithm is built on the principles of statistical estimation: the spectral radiances and various a priori constraints on aerosol characteristics are considered as multisource data that are known with predetermined accuracy. The inversion is designed as a search for the best fit of all input data by a theoretical model that takes into account the different levels of accuracy of the fitted data. The algorithm allows a choice of normal or lognormal noise assumptions. The multivariable fitting is implemented by a stable numerical procedure combining matrix inversion and univariant relaxation. The theoretical inversion scheme has been realized in the advanced algorithm retrieving aerosol size distribution together with complex refractive index from the spectral measurements of direct and diffuse radiation. The aerosol particles are modeled as homogeneous spheres. The atmospheric radiative transfer modeling is implemented with well-established publicly available radiative transfer codes. The retrieved refractive indices can be wavelength dependent; however, the extended smoothness constraints are applied to its spectral dependence (and indirectly through smoothness constraints on retrieved size distributions). The positive effects of statistical optimization on the retrieval results as well as the importance of applying a priori constraints are discussed in detail for the retrieval of both aerosol size distribution and complex refractive index. The developed algorithm is adapted for the retrieval of aerosol properties from measurements made by ground-based Sun-sky scanning radiometers used in the Aerosol Robotic Network (AERONET). The results of numerical tests together with examples of experimental data inversions are presented. C1 NASA, Goddard Space Flight Ctr, SSAI, Terr Phys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. RP Dubovik, O (reprint author), NASA, Goddard Space Flight Ctr, SSAI, Terr Phys Lab, Code 923, Greenbelt, MD 20771 USA. EM dubovik@aeronet.gsfc.nasa.gov RI Dubovik, Oleg/A-8235-2009; King, Michael/C-7153-2011 OI Dubovik, Oleg/0000-0003-3482-6460; King, Michael/0000-0003-2645-7298 NR 64 TC 1091 Z9 1163 U1 13 U2 106 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 AUG 27 PY 2000 VL 105 IS D16 BP 20673 EP 20696 DI 10.1029/2000JD900282 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 350NH UT WOS:000089107600017 ER PT J AU Chandler, MA Sohl, LE AF Chandler, MA Sohl, LE TI Climate forcings and the initiation of low-latitude ice sheets during the Neoproterozoic Varanger glacial interval SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Review ID OCEAN HEAT-TRANSPORT; MERIDIONAL ENERGY TRANSPORTS; EARTHS EARLY ATMOSPHERE; CARBON-DIOXIDE CLOUDS; SOUTH-AUSTRALIA; PALEOMAGNETIC DATA; SNOWBALL EARTH; SURFACE TEMPERATURES; MODEL SIMULATIONS; LOW PALEOLATITUDE AB The GISS GCM was used to determine if a diverse set of climate forcings, alone or in combination, could have initiated the low-latitude ice sheets of the Varanger (similar to 600 Ma) glacial interval. The simulations use a realistic reconstruction of the paleocontinental distribution and test the following forcings, alone and in combination: 6% solar luminosity decrease, four atmospheric CO2 scenarios (1260, 315, 140, and 40 ppm), a 50% increase and a 50% decrease in ocean heat transports, and a change in obliquity to 60 degrees. None of the forcings, individually, produced year-round snow accumulation on low-latitude continents, although the solar insolation decrease and 40 ppm CO2 scenarios allowed snow and ice to accumulate at high and middle latitudes. Combining forcings further cools the climate: when solar luminosity, CO2, and ocean heat transports were all decreased, annual mean freezing and snow accumulation extended across tropical continents. No simulation would have initiated low-latitude glaciation without contemporaneous glaciation at higher latitudes, a finding that matches the distribution of glacial deposits but which argues against high obliquity as a cause of the Varanger ice age. Lour-level clouds increased in most scenarios, as did surface albedo, while atmospheric water vapor amounts declined; all are positive feedbacks that drive temperatures lower. In the most severe scenario, global snow and ice cover increased to 68%, compared to 12% under modern conditions, and water vapor dropped by 90%. These results do not necessarily preclude a "snowball" Earth climate scenario for the Varanger glacial interval. However, either more severe forcings existed or radical changes occurred in the ocean/atmosphere system which are unaccounted for by the GCM. Also, as sea ice extent increased in these experiments, snow accumulation began to decline, because of an increasingly dry atmosphere. Under snowball Earth conditions, glaciation would be impossible, since the hydrological cycle would all but cease if the atmosphere's primary moisture source were cut off. C1 NASA, Goddard Inst Space Studies, Ctr Climate Syst Res, New York, NY 10025 USA. Columbia Univ, Lamont Doherty Earth Observ, Dept Earth & Environm Sci, Palisades, NY 10964 USA. RP Chandler, MA (reprint author), NASA, Goddard Inst Space Studies, Ctr Climate Syst Res, 2880 Broadway, New York, NY 10025 USA. EM mchandler@giss.nasa.gov; sohl@ldeo.columbia.edu NR 135 TC 69 Z9 72 U1 3 U2 6 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 AUG 27 PY 2000 VL 105 IS D16 BP 20737 EP 20756 DI 10.1029/2000JD900221 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 350NH UT WOS:000089107600021 ER EF