FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Deshpande, MD Reddy, CJ Beck, FB Cockrell, CR AF Deshpande, MD Reddy, CJ Beck, FB Cockrell, CR TI Application of modal expansion and method of moments to study electromagnetic scattering from a rectangular cavity recessed in a three-dimensional conducting surface SO RADIO SCIENCE LA English DT Article ID TE SCATTERING; PLANE; TRANSMISSION; FORMULATION; APERTURE; RAY AB The problem of electromagnetic (EM) scattering from an aperture backed by a rectangular cavity recessed in a three-dimensional (3-D) conducting body is analyzed using the modal expansion inside and the integral equation method outside the cavity. Assuming (1) an equivalent electric surface current density flowing on the 3-D conducting surface of the object including the cavity aperture and (2) an equivalent magnetic surface current density flowing over the aperture, only the scattered fields outside the cavity are determined. The EM fields inside the cavity are determined using the waveguide modal expansion functions. Making the total tangential electric and magnetic fields across the aperture continuous and subjecting the total tangential electric field on the outer conducting 3-D surface of the object to zero, a set of coupled integral equations is obtained. The equivalent electric and magnetic surface currents are then obtained by solving the coupled integral equation using the method of moments (MoM). The numerical results on scattering from rectangular cavities embedded in various 3-D objects are compared with the results obtained by other numerical techniques. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. HAMPTON UNIV,SCH ENGN & TECHNOL,DEPT ELECT ENGN,HAMPTON,VA 23668. RP Deshpande, MD (reprint author), VIGYAN INC,30 RES DR,HAMPTON,VA 23681, USA. NR 19 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD SEP-OCT PY 1996 VL 31 IS 5 BP 1291 EP 1298 DI 10.1029/96RS02171 PG 8 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA VK772 UT WOS:A1996VK77200028 ER PT J AU Chung, SK Thiessen, DB Rhim, WK AF Chung, SK Thiessen, DB Rhim, WK TI A noncontact measurement technique for the density and thermal expansion coefficient of solid and liquid materials SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID CONTAINERLESS AB A noncontact measurement technique for the density and the thermal expansion coefficient of refractory materials in their molten as well as solid phases is presented This technique is based on the video image processing of a levitated sample. Experiments were performed using the high-temperature electrostatic levitator (HTESL) at the Jet Propulsion Laboratory in which 2-3 mm diam samples can be levitated, melted, and radiatively cooled in vacuum. Due to the axisymmetric nature of the molten samples when levitated in the HTESL, a rather simple digital image analysis can be employed to accurately measure the volumetric change as a function of temperature. Density and the thermal expansion coefficient measurements were made on a pure nickel sample to test the accuracy of the technique in the temperature range of 1045-1565 degrees C. The result for the liquid phase density can be expressed by rho = 8.848 + (6.730 x 10(-4)) x T (degrees C) g/cm(3) within 0.8% accuracy, and the corresponding thermal expansion coefficient can be expressed by beta = (9.419 x 10(-5)) - (7.165 x 10(-9)) x T (degrees C) K-1 within 0.2% accuracy. (C) 1996 American Institute of Physics. RP Chung, SK (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI Thiessen, David/A-2731-2011 NR 13 TC 110 Z9 111 U1 5 U2 14 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD SEP PY 1996 VL 67 IS 9 BP 3175 EP 3181 DI 10.1063/1.1147584 PG 7 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA VH083 UT WOS:A1996VH08300028 ER PT J AU Somps, CJ Pickering, JL Madou, MJ Hines, JW Gibbs, DL AF Somps, CJ Pickering, JL Madou, MJ Hines, JW Gibbs, DL TI Electrochemical performance of an ion selective, polymeric membrane following chronic implantation in rat subcutaneous tissue SO SENSORS AND ACTUATORS B-CHEMICAL LA English DT Article; Proceedings Paper CT Symposium on Chemical Sensor Science and Technology, at the 6th International Meeting on Chemical Sensors Steering Committee CY JUL 22-25, 1996 CL GAITHERSBURG, MD DE ion selective electrode; polymer membrane; rat; subcutaneous; in vivo ID NEUTRAL CARRIER; ELECTRODES; SENSORS; ARRAY; TIME AB To determine if ion selective, poly (vinyl chloride) (PVC) membranes retain their electrochemical properties following chronic exposure to a physiologic environment, miniaturized, H+-selective electrodes are implanted subcutaneously in the rat for up to 21 days. Electrode stability, sensitivity, selectivity, response time and internal resistance are measured following implantation and compared to pre-implant values. We show that sensitivity and selectivity are decreased only slightly following implantation. Electrode stability and response times show small changes over implant duration. We conclude that, with the exception of drift, ion selective, PVC membranes retain much of their capacity for accurate electrochemical measures following as much as 21 days of direct and continuous exposure to rat subcutaneous tissue. C1 UNIV CALIF SAN FRANCISCO,FETAL TREATMENT CTR,SAN FRANCISCO,CA 94115. RP Somps, CJ (reprint author), NASA,AMES RES CTR,SENSORS 20001 PROGRAM,MOFFETT FIELD,CA 94035, USA. RI Madou, Marc/E-5869-2013 OI Madou, Marc/0000-0003-4847-3117 NR 15 TC 1 Z9 1 U1 0 U2 1 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0925-4005 J9 SENSOR ACTUAT B-CHEM JI Sens. Actuator B-Chem. PD SEP PY 1996 VL 35 IS 1-3 BP 222 EP 227 DI 10.1016/S0925-4005(97)80059-7 PG 6 WC Chemistry, Analytical; Electrochemistry; Instruments & Instrumentation SC Chemistry; Electrochemistry; Instruments & Instrumentation GA WB681 UT WOS:A1996WB68100039 ER PT J AU Allen, ER Hossner, LR Ming, DW Henninger, DL AF Allen, ER Hossner, LR Ming, DW Henninger, DL TI Release rates of phosphorus, ammonium, and potassium in clinoptilolite-phosphate rock systems SO SOIL SCIENCE SOCIETY OF AMERICA JOURNAL LA English DT Article ID CALCAREOUS SOILS; SURFACE-AREA; KINETICS; DISSOLUTION; SOLUBILITY; MIXTURES; TEXAS AB Controlled release of P, NH4, and K can be accomplished in synthetic soils through dissolution and cation-exchange reactions by phosphate rock (PR) and the zeolite mineral, clinoptilolite (Cp). The power-function equation has previously been found to adequately describe transport kinetics of the nutrient release process. Research was conducted to evaluate factors affecting P, NH4, and K release rates in Cp-PR systems, Data was collected using a continuous-how thin-disk technique, Results were evaluated with the power-function equation. Materials included a Texas Cp and North Carolina and Tennessee PRs. Variables examined included the Cp/PR ratio, the mole fraction of NH4 and K on the Cp, and the type of PR. The power-function model indicated that initial release rates and cumulative nutrient release in Cp-PR mixtures were increased by using a higher Cp/PR ratio and by using a more reactive PR. Nutrient release rates were also affected by changes in the proportion of NH4 and K occupying Cp exchange sites and reflected ion-selectivity characteristics of Cp, The results indicate that Cp and PR may be used to obtain a controlled release of NH4, P, and K in a synthetic soil. C1 TEXAS A&M UNIV,DEPT CROP & SOIL SCI,COLLEGE STN,TX 77840. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 24 TC 28 Z9 48 U1 3 U2 10 PU SOIL SCI SOC AMER PI MADISON PA 677 SOUTH SEGOE ROAD, MADISON, WI 53711 SN 0361-5995 J9 SOIL SCI SOC AM J JI Soil Sci. Soc. Am. J. PD SEP-OCT PY 1996 VL 60 IS 5 BP 1467 EP 1472 PG 6 WC Soil Science SC Agriculture GA VH791 UT WOS:A1996VH79100027 ER PT J AU Penn, MJ Jones, HP AF Penn, MJ Jones, HP TI Limb observations of HE I 1083 nm SO SOLAR PHYSICS LA English DT Article ID SOLAR CHROMOSPHERE; CORONAL HOLES; SPICULES; LINE; TEMPERATURE; HEIGHT; REGION; ALPHA; SUN AB Imaging spectroscopic data of the He I 1083 nm limb emission were taken on several dates in October and November 1995 with the NASA/NSO spectromagnetograph at the NSO/Kitt Peak vacuum telescope and on 9 December, 1993 with the Michigan infrared camera at the NSO/Sacramento Peak vacuum tower telescope. Emission line profiles were observed in quiet-Sun and coronal hole locations on the northern and southern solar poles and on the east solar limb. The height of the He I 1083 nm shell above the continuum limb at 1083 nm was measured to be 2.11 +/- 0.12 Mm with the Kitt Peak data, and 1.74 +/- 0.05 Mm with the Sacramento Peak data. The Kitt Peak data show (1) within the measurement error there is no significant difference in the height or thickness of the emission shell in coronal holes compared with the quiet Sun, (2) the 1083 nm emission intensity drops by 50% in coronal holes, (3) the line width decreases by about 2 km s(-1) in coronal holes (suggesting less inclined spicules), (4) the line width of the HeI 1083 nm line jumps significantly as the line of sight crosses the solar limb (consistent with a higher temperature upper shell), (5) a quiescent prominence shows a smaller spectral line width (consistent with a cooler temperature or less velocity broadening), and (6) the entire emission shell and the prominence show a He I spectral component ratio of about 8 (suggesting optically thin emission). C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP Penn, MJ (reprint author), NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,KP,POB 26732,TUCSON,AZ 85726, USA. NR 42 TC 12 Z9 12 U1 0 U2 0 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 1996 VL 168 IS 1 BP 19 EP 35 DI 10.1007/BF00145822 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VK881 UT WOS:A1996VK88100002 ER PT J AU Denning, AS Collatz, GJ Zhang, CG Randall, DA Berry, JA Sellers, PJ Colello, GD Dazlich, DA AF Denning, AS Collatz, GJ Zhang, CG Randall, DA Berry, JA Sellers, PJ Colello, GD Dazlich, DA TI Simulations of terrestrial carbon metabolism and atmospheric CO2 in a general circulation model .1. Surface carbon fluxes SO TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY LA English DT Article ID NET PRIMARY PRODUCTIVITY; LARGE-SCALE ENVIRONMENT; CUMULUS CLOUD ENSEMBLE; SIMPLE BIOSPHERE MODEL; BOUNDARY-LAYER; LATITUDINAL DISTRIBUTION; STOMATAL CONDUCTANCE; CLIMATE-CHANGE; GLOBAL-MODEL; EXCHANGE AB The exchange of carbon dioxide (CO2) between the atmosphere and terrestrial ecosystems due to photosynthesis and respiration has been simulated using a new version of the simple biosphere model (SiB2) and the Colorado State University (CSU) general circulation model (GCM). Parameters associated with the extent and seasonality of vegetation were derived from satellite observations. The fluxes were calculated at the GCM time step of 6 min, so that the diurnal cycle of photosynthesis is well resolved. Annual net primary productivity simulated by the coupled model agrees well with previous estimates in most regions of the world. In some regions (central North America, southeastern South America, southeast Asia), the precipitation simulated by the CSU GCM is less than observed, and in those regions the simulated NPP is less than previous estimates. The amplitude of the seasonal cycle of the simulated net flux is quite similar to previous estimates, but the phase is significantly earlier in the northern temperate and boreal zones, both as simulated by the GCM and when SiB2 is driven off-line using observed meteorological forcing. At the few locations for which observational data are available, the phase of the simulated seasonal cycle of net carbon fluxes agrees well with the data, but at one temperate forest grid cell the amplitude is too low. The phase of the simulated diurnal cycle reproduces observations from a temperate forest, temperate grassland, and tropical forest. The amplitude of the simulated diurnal cycle is close to the observed amplitude early in the season at the temperate grassland site, but deteriorates by late summer because of drought stress due to the less-than-observed simulated precipitation. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. COLORADO STATE UNIV, DEPT ATMOSPHER SCI, FT COLLINS, CO 80521 USA. CARNEGIE INST WASHINGTON, DEPT PLANT BIOL, STANFORD, CA 94305 USA. RP Denning, AS (reprint author), UNIV CALIF SANTA BARBARA, SCH ENVIRONM SCI & MANAGEMENT, SANTA BARBARA, CA 93106 USA. RI collatz, george/D-5381-2012; Denning, Scott/F-4974-2011; Randall, David/E-6113-2011 OI Denning, Scott/0000-0003-3032-7875; Randall, David/0000-0001-6935-4112 NR 68 TC 122 Z9 125 U1 2 U2 19 PU CO-ACTION PUBLISHING PI JARFALLA PA RIPVAGEN 7, JARFALLA, SE-175 64, SWEDEN SN 0280-6509 J9 TELLUS B JI Tellus Ser. B-Chem. Phys. Meteorol. PD SEP PY 1996 VL 48 IS 4 BP 521 EP 542 DI 10.1034/j.1600-0889.1996.t01-2-00009.x PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VP642 UT WOS:A1996VP64200009 ER PT J AU Denning, AS Randall, DA Collatz, GJ Sellers, PJ AF Denning, AS Randall, DA Collatz, GJ Sellers, PJ TI Simulations of terrestrial carbon metabolism and atmospheric CO2 in a general circulation model .2. Simulated CO2 concentrations SO TELLUS SERIES B-CHEMICAL AND PHYSICAL METEOROLOGY LA English DT Article; Proceedings Paper CT Symposium on the Breathing of the Earth - Observational Constraints for Models of the Terrestrial Biosphere, at the IUGG XXI General Assembly CY JUL 02-14, 1995 CL BOULDER, CO SP IUGG ID LARGE-SCALE ENVIRONMENT; CUMULUS CLOUD ENSEMBLE; LATITUDINAL DISTRIBUTION; BOUNDARY-LAYER; DIOXIDE; TRANSPORT; EXCHANGE; INVERSION; BIOSPHERE; RADIATION AB The effects of terrestrial photosynthesis and respiration on the mixing ratio of atmospheric CO2 have been simulated using surface fluxes calculated using a new version of the simple biosphere model (SiB2) coupled to the Colorado State University (CSU) general circulation model (GCM). The model was integrated for 5 years from an initial condition of uniform CO2, with surface fluxes and atmospheric transport calculated on a 6-min time step, Subgrid-scale vertical transport includes the effects of cumulus and dry convection and boundary layer turbulence, with diurnal cycles of all processes well resolved. The amplitude and phase of the diurnal cycle of simulated CO2 concentration during the growing season agreed very well with observations made in Brazil, the southeastern United States, and central Canada, and the vertical structure of the simulated diurnal variations of CO2 in the lower troposphere appears to be fairly realistic. By contrast, when the model was driven with surface fluxes of CO2 derived from monthly means saved from the on-line simulation, the diurnal cycle was much weaker than observed at all three locations and was nearly 180 degrees out of phase with the observations. The amplitude and phase of the seasonal cycle of simulated concentration show good agreement with data collected in remote marine areas by the flask sampling network. Vertical attenuation of the seasonal amplitude in the model is stronger than observed, at least over the western Pacific ocean where seasonal data have been collected by aircraft. In the annual mean, correlations between the carbon fluxes and vertical atmospheric transport produce very strong concentration maxima over the tropical rain forests, but covariance of fluxes and transport on the seasonal time scale are more important in the middle latitudes. The effect of these correlations is to impose a vertical gradient of several parts per million on the zonal mean atmospheric CO2 concentration over biologically active regions, with the seasonal cycle contributing about 75% of the effect and the diurnal cycle contributing about 25%. The simulated annual mean meridional gradient in concentration at the flask stations is much stronger than has been simulated with off-line tracer transport models, accounting for more than half of the observed north-south gradient. C1 COLORADO STATE UNIV,DEPT ATMOSPHER SCI,FT COLLINS,CO 80521. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Denning, AS (reprint author), UNIV CALIF SANTA BARBARA,SCH ENVIRONM SCI & MANAGEMENT,SANTA BARBARA,CA 93106, USA. RI collatz, george/D-5381-2012; Denning, Scott/F-4974-2011; Randall, David/E-6113-2011 OI Denning, Scott/0000-0003-3032-7875; Randall, David/0000-0001-6935-4112 NR 40 TC 98 Z9 99 U1 0 U2 13 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0280-6509 J9 TELLUS B JI Tellus Ser. B-Chem. Phys. Meteorol. PD SEP PY 1996 VL 48 IS 4 BP 543 EP 567 DI 10.1034/j.1600-0889.1996.t01-1-00010.x PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VP642 UT WOS:A1996VP64200010 ER PT J AU Salas, MD Iollo, A AF Salas, MD Iollo, A TI Entropy jump across an inviscid shock wave SO THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS LA English DT Article AB The Shock jump conditions for the Euler equations in their primitive form are derived by using generalized functions. The shock profiles for specific volume, speed, and pressure and shown to be the same, however, density has a different shock profile. Careful study of the equations that govern the entropy shows that the inviscid entropy profile has a local maximum within the shock layer. We demonstrate that because of this phenomenon, the entropy propagation equation cannot be used as a conservation law. C1 POLITECN TORINO, DIPARTIMENTO INGN AERONAUT & SPAZIALE, I-10129 TURIN, ITALY. RP Salas, MD (reprint author), NASA, LANGLEY RES CTR, MAIL STOP 139, HAMPTON, VA 23681 USA. NR 11 TC 3 Z9 3 U1 0 U2 0 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0935-4964 J9 THEOR COMP FLUID DYN JI Theor. Comput. Fluid Dyn. PD SEP PY 1996 VL 8 IS 5 BP 365 EP 375 PG 11 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA VL606 UT WOS:A1996VL60600003 ER PT J AU Rubinstein, R AF Rubinstein, R TI A relaxation approximation for time-dependent second-order effects in shear turbulence SO THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS LA English DT Article ID EDDY-VISCOSITY-TYPE; REYNOLDS-STRESS; RENORMALIZATION-GROUP; MODELS; FLOWS; REPRESENTATION; CLOSURES AB The Crow constraint on time-dependent turbulence models is generalized to effects of second order in the strain rate. For simple shear flow, this generalization requires agreement of the time-dependent normal stress deviators with the short-time rapid distortion limit and with long-time equilibrium data. A model consistent with these requirements is proposed based on a perturbative solution of the equations of the direct interaction approximation for shear flow. It requires a decomposition of the Reynolds stress into tensor components which satisfy coupled linear relaxation equations. This approach to time-dependent turbulence modeling based on analytical theories offers an alternative to the standard ones, in which various hypotheses are introduced to close correlations in the exact transport equation for second-order single-point moments. RP Rubinstein, R (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681, USA. NR 23 TC 5 Z9 5 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0935-4964 J9 THEOR COMP FLUID DYN JI Theor. Comput. Fluid Dyn. PD SEP PY 1996 VL 8 IS 5 BP 377 EP 386 PG 10 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA VL606 UT WOS:A1996VL60600004 ER PT J AU Conkin, J Foster, PP Powell, MR Waligora, JM AF Conkin, J Foster, PP Powell, MR Waligora, JM TI Relationship of the time course of venous gas bubbles to altitude decompression illness SO UNDERSEA & HYPERBARIC MEDICINE LA English DT Article DE maximum likelihood; hypobaric chambers; aviators; time-series analysis ID DIRECT ASCENT; SICKNESS AB The correlation is low between the occurrence of gas bubbles in the pulmonary artery, called venous gas emboli (VGE), and subsequent decompression illness (DCI). The correlation improves when a ''grade'' of VGE is considered; a zero to four categorical classification based on the intensity and duration of the VGE signal from a Doppler bubble detector. Additional insight about DCI might come from an analysis of the time course of the occurrence of VGE. Using the NASA Hypobaric Decompression Sickness Databank, we compared the time course of the VGE outcome between 322 subjects who exercised and 133 Doppler technicians who did not exercise to evaluate the role of physical activity on the VGE outcome and incidence of DCI. We also compared 61 subjects with VGE and DCI with 110 subjects with VGE but without DCI to identify unique characteristics about the time course of the VGE outcome to try to discriminate between DCI and no-DCI cases. The VGE outcome as a function of time showed a characteristic short lag, rapid response, and gradual recovery phase that was related to physical activity at altitude and the presence or absence of DCL The average time for DCI symptoms in a limb occurred just before the time of the highest fraction of VGE in the pulmonary artery. It is likely, but not certain, that an individual wilt report a DCI symptom if VGE are detected early in the altitude exposure, the intensity or grade of VGE rapidly increases from a limb region, and the intensity or grade of VGE remains high. C1 NASA,LYNDON B JOHNSON SPACE CTR,LIFE SCI RES LABS,HOUSTON,TX 77058. RP Conkin, J (reprint author), UNIV SPACE RES ASSOC,DIV SPACE LIFE SCI,3600 BAY AREA BLVD,HOUSTON,TX 77058, USA. NR 28 TC 14 Z9 14 U1 0 U2 1 PU UNDERSEA & HYPERBARIC MEDICAL SOC INC PI KENSINGTON PA 10531 METROPOLITAN AVE, KENSINGTON, MD 20895 SN 1066-2936 J9 UNDERSEA HYPERBAR M JI Undersea Hyperb. Med. PD SEP PY 1996 VL 23 IS 3 BP 141 EP 149 PG 9 WC Marine & Freshwater Biology; Medicine, Research & Experimental SC Marine & Freshwater Biology; Research & Experimental Medicine GA VR925 UT WOS:A1996VR92500004 PM 8931281 ER PT J AU Iglesias, A Erda, L Rosenzweig, C AF Iglesias, A Erda, L Rosenzweig, C TI Climate change in Asia: A review of the vulnerability and adaptation of crop production SO WATER AIR AND SOIL POLLUTION LA English DT Article; Proceedings Paper CT Regional Workshop on Climate Change Vulnerability and Adaptation in Asia and the Pacific CY JAN 15-19, 1996 CL MANILA, PHILIPPINES SP Philippine Atmospher Geophys & Astron Serv Adm, US Country Studies Program, Asian Dev Bank DE Asia; agriculture; El Nino ID IMPACT AB A number of studies have provided quantitative assessments of the potential climate change impacts on crop production in Asia. Estimates take into account (a) uncertainty in the level of climate change expected, using a range of climate change scenarios; (b) physiological effects of carbon dioxide on the crops; and (c) different adaptive responses. In all cases, the effects of climate change induced by increased atmospheric carbon dioxide depended on the counteracting effects among higher daily evapotranspiration rates, shortening of crop growth duration, and changes in precipitation patterns, as well as the effects of carbon dioxide on crop growth and water-use efficiency. Although results varied depending on the geographical locations of the regions tested, the production of rice (the main food crop in the region) generally did not benefit from climate change. In South and Southeast Asia, there is concern about how climate change may affect El Nino/Southern Oscillation events, since these play a key role in determining agricultural production. Furthermore, problems arising from variability of water availability and soil degradation are currently major challenges to agriculture in the region. These problems may be exacerbated in the future if global climate change projections are realized. Many studies have considered strategies for improving agricultural management, based on the optimization of crop management decisions. Climate change analyses could be further strengthened by economic studies that integrate the potential use of natural resources across sectors. C1 CHINESE ACAD AGR SCI,BEIJING 100081,PEOPLES R CHINA. NASA,GODDARD INST SPACE STUDIES,GREENBELT,MD. RP Iglesias, A (reprint author), INIA,CIFOR,CARRETERA CORUNA KM 7,MADRID 28040,SPAIN. NR 61 TC 20 Z9 22 U1 0 U2 22 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0049-6979 J9 WATER AIR SOIL POLL JI Water Air Soil Pollut. PD SEP PY 1996 VL 92 IS 1-2 BP 13 EP 27 PG 15 WC Environmental Sciences; Meteorology & Atmospheric Sciences; Water Resources SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences; Water Resources GA VM538 UT WOS:A1996VM53800004 ER PT J AU Peltzer, G Rosen, P Rogez, F Hudnut, K AF Peltzer, G Rosen, P Rogez, F Hudnut, K TI Postseismic rebound in fault step-overs caused by pore fluid flow SO SCIENCE LA English DT Article ID LANDERS EARTHQUAKE SEQUENCE; 28 JUNE 1992; DIFFERENTIAL RADAR INTERFEROMETRY; SOUTHERN-CALIFORNIA; DEFORMATION; VALLEY AB Near-field strain induced by large crustal earthquakes results in changes in pore fluid pressure that dissipate with time and produce surface deformation, Synthetic aperture radar(SAR) interferometry revealed several centimeters of postseismic uplift in pull-apart structures and subsidence in a compressive jog along the Landers, California, 1992 earthquake surface rupture, with a relaxation time of 270 +/- 45 days. Such a postseismic rebound may be explained by the transition of the Poisson's ratio of the deformed volumes of rock fl-om undrained to drained conditions as pore fluid flow allows pore pressure to return to hydrostatic equilibrium. C1 US GEOL SURVEY,PASADENA,CA 91125. RP Peltzer, G (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Hudnut, Kenneth/B-1945-2009; Hudnut, Kenneth/G-5713-2010 OI Hudnut, Kenneth/0000-0002-3168-4797; NR 28 TC 137 Z9 142 U1 3 U2 10 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 30 PY 1996 VL 273 IS 5279 BP 1202 EP 1204 DI 10.1126/science.273.5279.1202 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA VE476 UT WOS:A1996VE47600031 ER PT J AU Tanre, D Herman, M Kaufman, YJ AF Tanre, D Herman, M Kaufman, YJ TI Information on aerosol size distribution contained in solar reflected spectral radiances SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLOUD-CONDENSATION-NUCLEI; SAHARAN DUST OUTBREAKS; SCALE AIR-POLLUTION; SATELLITE IMAGERY; TROPOSPHERIC AEROSOLS; OCEAN COLOR; 3-DIMENSIONAL MODEL; REMOTE MEASUREMENTS; OPTICAL-PROPERTIES; RADIATION BUDGET AB Information on the aerosol size distribution contained in the reflected solar spectral radiances detected over the oceans can be reduced into two quantities. These quantities have been determined in an unbiased way with the use of the principal components. Consequently, only one to two parameters of the size distribution can be retrieved. For a single-mode distribution these parameters are the effective radius of the particles and the width of the size distribution. The accuracy of the retrieval depends on the view and illumination directions. Accurate knowledge of the refractive index, real and imaginary parts, is not critically important for the retrieval as long as the retrieved particles are smaller than 1.0 mu m. An error budget shows that very clean conditions are not suitable for getting any information on the aerosol size distribution. A surprising result of this investigation is that the spectral reflectance of a bimodal-lognormal distribution can be simulated very well with spectral reflectance of a single lognormal with an appropriate radius and width of distribution, a, that do not necessary correspond to an average of the bimodal values. The present results change drastically our philosophy regarding the retrieval scheme. Additional studies are needed to confirm the present results for nonspherical particles. C1 UNIV SCI & TECHNOL LILLE, F-59655 VILLENEUVE DASCQ, FRANCE. NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RP CNRS, OPT ATMOSPHER LAB, BAT P5, F-59655 VILLENEUVE DASCQ, FRANCE. NR 95 TC 89 Z9 92 U1 2 U2 7 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 AUG 27 PY 1996 VL 101 IS D14 BP 19043 EP 19060 DI 10.1029/96JD00333 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VE258 UT WOS:A1996VE25800007 ER PT J AU Zhang, C Dazlich, DA Randall, DA Sellers, PJ Denning, AS AF Zhang, C Dazlich, DA Randall, DA Sellers, PJ Denning, AS TI Calculation of the global land surface energy, water and CO2 fluxes with an off-line version of SiB2 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODELS; SIMPLE BIOSPHERE MODEL; STOMATAL CONDUCTANCE; SPATIAL VARIABILITY; BOUNDARY-LAYER; PHOTOSYNTHESIS; PARAMETERIZATION; TRANSPIRATION; TEMPERATURE; VEGETATION AB Global land surface fluxes of energy and CO2 have been simulated using an off-line version of a biosphere-atmosphere model, SiB2, forced with analyzed or observed atmospheric boundary layer mean potential temperature, water vapor mixing ratio, and wind, surface downward solar and thermal radiation, and precipitation. The off-line model is called SiBDRV. Soil and vegetation boundary conditions were specified from satellite data and other sources. The European Centre for Medium-Range Weather Forecasts (ECMWF) data assimilation system products were used to derive the atmospheric and radiative forcings. Precipitation was based on station observations. The SiBDRV results were compared with corresponding simulation results produced by the Colorado State University general circulation model (CSU GCM), with the ECMWF assimilation system output and with observations. Differences between the surface energy budget components and the surface climatology produced by SiBDRV and the ECMWF assimilation system are due to differences in the land surface parameterizations between the two models. SiBDRV produced lower surface latent heat fluxes and larger sensible heat fluxes than the ECMWF data assimilation, partly due to large canopy resistent term explicitly formulated by SiB2 and possible precipitation differences between the SiBDRV precipitation forcing and the ECMWF data. Differences between the SiBDRV and the CSU GCM results are due to the different climates associated with the ECMWF assimilation system output, which is strongly constrained by assimilated observations, and by the CSU GCM, which is run in pure simulation mode. More specifically, the major reasons for the surface energy and CO2 budget differences between the SiBDRV and the GCM are greater incoming solar radiation in the GCM and differences in the precipitation patterns. The simulated global annual carbon uptake by the terrestrial biosphere is similar in SiBDRV and the GCM. The annual gross primary productions of SiBDRV (116 Gt) and the GCM (113 Ct) agree well with other studies, using either ecological process models or empirical regression models. SiBDRV takes up 10 and 5% more CO2 than the GCM in January and July, respectively. The seasonally varying land surface CO2 fluxes estimated by the SiBDRV and the GCM both compare reasonably well with the results of other calculations. C1 NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RP Zhang, C (reprint author), COLORADO STATE UNIV, DEPT ATMOSPHER SCI, FT COLLINS, CO 80523 USA. RI Denning, Scott/F-4974-2011; Randall, David/E-6113-2011 OI Denning, Scott/0000-0003-3032-7875; Randall, David/0000-0001-6935-4112 NR 44 TC 19 Z9 22 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 1996 VL 101 IS D14 BP 19061 EP 19075 DI 10.1029/96JD01449 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VE258 UT WOS:A1996VE25800008 ER PT J AU Wu, DL Hays, PB Roble, RG AF Wu, DL Hays, PB Roble, RG TI Doppler imager wind measurements with simulations from the NCAR thermosphere-ionosphere-mesosphere electrodynamics circulation model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EQUATORIAL MIDDLE ATMOSPHERE; GRAVITY-WAVE ENERGY; GENERAL-CIRCULATION; DIURNAL TIDE; SEMIDIURNAL TIDE; SOLAR TIDES; PROPAGATING TIDES; MOMENTUM FLUXES; MEAN WINDS; VARIABILITY AB In this paper a comparison is presented between simulations of the diurnal and semidiurnal tides in the middle and upper atmosphere from the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIMEGCM) and satellite observations from the Upper Atmosphere Research Satellite (UARS) high-resolution Doppler imager (HRDI). Reasonable agreement is found between the model and observations for a March condition when a strong diurnal tide was observed. The model is able to reproduce many tidal features at altitudes between 65 and 110 km as observed in the HRDI wind measurements. Of interest in these features is the shortening vertical wavelength of the (1,1) tide in the upper mesosphere and lower thermosphere, which appears in both model simulations and the wind observations. The HRDI data also show large longitudinal variations in the diurnal tide, of which the amplitude can be as high as similar to 50% of the migrating tide. The wavelike structures in latitude and altitude dimensions suggest that the longitudinal variations are likely due to the presence of propagating nonmigrating tides in the upper mesosphere and lower thermosphere. For further investigations of the observed tidal variability the model demonstrates great potential with the use of more realistic heating/cooling and wave forcing schemes. C1 UNIV MICHIGAN, DEPT ATMOSPHER OCEAN & SPACE SCI, ANN ARBOR, MI 48109 USA. NATL CTR ATMOSPHER RES, HIGH ALTITUDE OBSERV, BOULDER, CO 80307 USA. RP Wu, DL (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Wu, Dong/D-5375-2012 NR 52 TC 5 Z9 5 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 AUG 27 PY 1996 VL 101 IS D14 BP 19147 EP 19160 DI 10.1029/96JD01398 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VE258 UT WOS:A1996VE25800015 ER PT J AU Tegen, I Lacis, AA AF Tegen, I Lacis, AA TI Modeling of particle size distribution and its influence on the radiative properties of mineral dust aerosol SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article; Proceedings Paper CT International Specialty Conference on Aerosols and Atmospheric Optics - Radiative Balance and Visual Air Quality CY SEP 26-30, 1994 CL SNOWBIRD, UT SP Air & Waste Management Assoc, Amer Geophys Union ID LIGHT-SCATTERING; ATMOSPHERE; CLIMATE; SOILS AB The radiative parameters of mineral aerosols are strongly dependent on particle size. Therefore explicit modeling of particle size distribution is needed to calculate the radiative effects and the climate impact of mineral dust. We describe a parameterization of the global mineral aerosol size distribution in a transport model using eight size classes between 0.1 and 10 mu m. The model prescribes the initial size distribution using soil texture data and aerosol size measurements close to the ground. During transport, the size distribution changes as larger particles settle out faster than smaller particles. Results of Mie scattering calculations of radiative parameters (extinction efficiency, single scattering albedo, asymmetry parameter) of mineral dust are shown at wavelengths between 0.3 and 30 mu m for effective particle radii between 0.1 and 10 mu m. Also included are radiative properties (reflection, absorption, transmission) calculated for a dust optical thickness of 0.1. Preliminary studies with the Goddard Institute for Space Studies (GISS) general circulation model (GCM), using two particle size modes, show regional changes in radiative flux at the top of the atmosphere as large as +15 W m(-2) at solar and +5 W m(-2) at thermal wavelengths in the annual mean, indicating that dust forcing is an important factor in the global radiation budget. C1 COLUMBIA UNIV, DEPT APPL PHYS, NEW YORK, NY 10027 USA. RP NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Lacis, Andrew/D-4658-2012 NR 26 TC 317 Z9 336 U1 6 U2 40 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 AUG 27 PY 1996 VL 101 IS D14 BP 19237 EP 19244 DI 10.1029/95JD03610 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VE258 UT WOS:A1996VE25800026 ER PT J AU Kaufman, YJ Holben, BN AF Kaufman, YJ Holben, BN TI Hemispherical backscattering by biomass burning and sulfate particles derived from sky measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article; Proceedings Paper CT 5th International Conference on Carbonaceous Particles in the Atmosphere CY AUG 23-26, 1994 CL LAWRENCE BERKELEY NATL LAB, BERKELEY, CA SP Lawrence Berkeley Natl Lab, Lawrence Livermore Natl Lab HO LAWRENCE BERKELEY NATL LAB ID AEROSOL SIZE DISTRIBUTIONS; CLOUD-CONDENSATION-NUCLEI; GLOBAL RADIATION BUDGET; SATELLITE MEASUREMENTS; ATMOSPHERIC CHEMISTRY; 3-DIMENSIONAL MODEL; OPTICAL-PROPERTIES; NORTH-ATLANTIC; BOUNDARY-LAYER; PHASE FUNCTION AB Holben et al. [1995] reported measurements of the aerosol spectral optical thickness and derived volume size distribution from measurements of the sky spectral radiance in the aureole (scattering angle less than or equal to 40 degrees). In this paper we use these and other sky data for analysis of the aerosol,hemispheric backscattering ratio beta for two aerosol types: smoke aerosol, prevailing during the biomass burning season in the Amazon and the Cerrado in 1993, and predominately sulfate aerosol, measured during the Sulfate/Smoke Cloud and Radiation-Atlantic field experiment in the eastern United States in 1993. The beta determines the efficiency (per unit of optical thickness) of the aerosol particles to reflect radiation back to space and therefore to generate a negative radiative forcing of climate. The average value of beta, using the Wiscombe and Grams [1976] definition, beta(WG), varied between 0.20 and 0.28 for both aerosol types, as compared to beta(WG) = 0.29 used by Charlson. et al. [1992] and Penner et al. [1992] to calculate radiative forcing by sulfate and smoke aerosol, respectively. The variable beta(WG) is an average value of beta on all the illumination directions. However, high optical thicknesses occur in the Amazon and eastern United States during the period of July to September, when the solar elevation is high. For these months and the latitude range the actual average value of beta is 25% lower than beta(WG) for the same aerosol type. A combination of these two factors results in values of beta, and the corresponding aerosol direct radiative forcing, that are 30-50% lower from these estimates. The climate modeling of Kiehl and Briegleb [1993] uses actual computations of the sulfate aerosol hemispherical backscattering as a function of time and geographic position for a particle radius of 0.2 mu m, which corresponds very closely to the present results. The volume size distribution, used to derive beta, was obtained from sky radiances for scattering angle less than or equal to 40 degrees, assuming spherical homogeneous particles. It can be compared with values of beta derived from the whole sky almucantar radiance (scattering angle less than or equal to 140 degrees) that reflects the; true aerosol scattering phase function. The two values of beta did not differ significantly. C1 NASA, GODDARD SPACE FLIGHT CTR, TERR PHYS LAB, GREENBELT, MD 20771 USA. RP NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. NR 51 TC 29 Z9 33 U1 0 U2 2 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 AUG 27 PY 1996 VL 101 IS D14 BP 19433 EP 19445 DI 10.1029/95JD02532 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VE258 UT WOS:A1996VE25800043 ER PT J AU Holben, BN Setzer, A Eck, TF Pereira, A Slutsker, I AF Holben, BN Setzer, A Eck, TF Pereira, A Slutsker, I TI Effect of dry-season biomass burning on Amazon basin aerosol concentrations and optical properties, 1992-1994 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article; Proceedings Paper CT 5th International Conference on Carbonaceous Particles in the Atmosphere CY AUG 23-26, 1994 CL LAWRENCE BERKELEY NATL LAB, BERKELEY, CA SP Lawrence Berkeley Natl Lab, Lawrence Livermore Natl Lab HO LAWRENCE BERKELEY NATL LAB ID ANTHROPOGENIC AEROSOLS; RADIATION; TROPICS AB Aerosol concentrations and properties have been derived from a network of ground-based Sun-sky radiometer measurements in Brazil's Amazon basin region since 1992. The measurements characterize the background aerosol environment and aerosol emissions from biomass burning at eight selected sites. The duration and frequency of the measurements provide the foundation of an aerosol climatology based on direct sun measurements of aerosol optical thickness and retrievals of size distribution from solar aureole measurements. The aerosol optical thickness measurements clearly illustrate that for sites located within regions of biomass burning the duration of smoke above background levels often exceeds 2 months and frequently at levels an order of magnitude above background. The aerosol optical thickness range during preburning conditions was 0.11 to 0.27 at 440 nm. Under these conditions, stratospheric aerosols from Pinatubo constituted a significant part of the signal in 1993 but were about 50% less in 1994. During the burning season; smoke elevated the aerosol optical thickness above 1.0 for seasonally averaged values measured at 440 nm at sites located in active source regions in Mate Grosso, Rondonia, and Tocantins states. The measurement sites are located in the cerrado and forest conversion areas. Analysis of the size distribution of the particles indicated that the increase in aerosol optical thickness was associated with an increase of an accumulation and coarse particle modes. The asymmetry factor ''g'', computed from the phase function, showed considerable spectral dependence between the preburning and burning seasonal phases. The 1020-nm channel was reduced from 0.66 to similar to 0.53, while at 440 nm little seasonal phase variation was noted. Conditions of burning were sufficiently strong that the atmospheric conditions associated with the climatological definition of a dry season was subdivided into (1) preburning, (2) transition to burning, (3) burning, and (4) transition to wet season phases for most sites. Averages and frequency distributions were used to characterize each seasonal phase by site. Changes in total column water vapor amount, also retrieved from direct sun measurements, did not have an apparent effect on the optical properties of the aerosols. C1 INST PESQUISAS ESPACIAIS, SAO PAULO, BRAZIL. NASA, GODDARD SPACE FLIGHT CTR, SCI SYST & APPLICAT INC, GREENBELT, MD 20771 USA. RP Holben, BN (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HUGES STX CORP, CODE 923, GREENBELT, MD 20771 USA. RI ECK, THOMAS/D-7407-2012 NR 28 TC 72 Z9 73 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 27 PY 1996 VL 101 IS D14 BP 19465 EP 19481 DI 10.1029/96JD01114 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VE258 UT WOS:A1996VE25800046 ER PT J AU Chui, TCP Goodstein, DL Harter, AW Mukhopadhyay, R AF Chui, TCP Goodstein, DL Harter, AW Mukhopadhyay, R TI Heat capacity anomalies of superfluid He-4 under the influence of a counterflow near T-lambda SO PHYSICAL REVIEW LETTERS LA English DT Article ID TRANSITION; HELIUM; FLOW; DEPRESSION; PRESSURE; POINT; SOUND AB We present a thermodynamic treatment of superfluid helium in the presence of an applied heat current, Q, which produces a counterflow velocity (W) over right arrow. We show that the heat capacity can be expressed in terms of the dependence of the superfluid density on (W) over right arrow. Near T-lambda, both mean field theory and renormalization group theory give a divergent heat capacity with an exponent of 0.5 at a depressed transition temperature. In contrast, if (W) over right arrow rather than Q is held constant, the heat capacity remains finite. C1 CALTECH,PASADENA,CA 91125. RP Chui, TCP (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 25 TC 17 Z9 17 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 AUG 26 PY 1996 VL 77 IS 9 BP 1793 EP 1796 DI 10.1103/PhysRevLett.77.1793 PG 4 WC Physics, Multidisciplinary SC Physics GA VD430 UT WOS:A1996VD43000034 ER PT J AU Guidry, J Clausen, CM Clausen, CA AF Guidry, J Clausen, CM Clausen, CA TI The development of a freon-free nonvolatile residue test for space flight hardware. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 UNIV CENT FLORIDA,DEPT CHEM,ORLANDO,FL 32816. NASA,KENNEDY SPACE CTR,FL 32889. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 38 EP ANYL PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VA915 UT WOS:A1996VA91500284 ER PT J AU Ricca, A Bauschlicher, CW AF Ricca, A Bauschlicher, CW TI DFT application of DFT to systems containing metal atoms. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 52 EP COMP PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VA915 UT WOS:A1996VA91501438 ER PT J AU Wright, CA McGill, J Gong, JK Hepp, AF AF Wright, CA McGill, J Gong, JK Hepp, AF TI From carbon dioxide to C-2 organic molecules SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 SE MISSOURI STATE UNIV,DEPT CHEM,CAPE GIRARDEAU,MO 63701. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 60 EP FUEL PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VA915 UT WOS:A1996VA91501870 ER PT J AU Jensen, BJ AF Jensen, BJ TI Modified phenylethynyl terminated polymides with lower melt viscosity SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 64 EP POLY PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VB009 UT WOS:A1996VB00900917 ER PT J AU Jensen, BJ AF Jensen, BJ TI Development of processable phenylethnyl terminated polyimides based on pyromellitic dianhydride SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 65 EP POLY PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VB009 UT WOS:A1996VB00900918 ER PT J AU Abdeldayem, HA Frazier, DO Penn, BG Witherow, WK Banks, C Shields, AD Hicks, RM AF Abdeldayem, HA Frazier, DO Penn, BG Witherow, WK Banks, C Shields, AD Hicks, RM TI Nonlinear optical properties of vapor deposited metal-free phthalocyanine thin films SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. USA,MISSILE COMMAND,CTR RES DEV & ENGN,REDSTONE ARSENAL,AL 35898. UNIV SPACE RES ASSOC,COLUMBIA,MD. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 139 EP ORGN PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VB009 UT WOS:A1996VB00900139 ER PT J AU Hergenrother, PM Smith, JG Connell, JW AF Hergenrother, PM Smith, JG Connell, JW TI Imide oligomers containing phenylethynyl groups SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 142 EP PMSE PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VB009 UT WOS:A1996VB00901421 ER PT J AU Thomas, JLC Bauschlicher, CW Hall, MB AF Thomas, JLC Bauschlicher, CW Hall, MB TI An ab initio study of the state-specific chemistry of the reaction of iron(I) with nitric oxide SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 TEXAS A&M UNIV,DEPT CHEM,COLLEGE STN,TX 77843. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Hall, Michael/B-9118-2013 OI Hall, Michael/0000-0003-3263-3219 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 151 EP COMP PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VA915 UT WOS:A1996VA91501536 ER PT J AU Lee, TJ AF Lee, TJ TI Determination of highly accurate heats of formation. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 195 EP COMP PN 1 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VA915 UT WOS:A1996VA91501580 ER PT J AU Moore, CE Cardelino, BH AF Moore, CE Cardelino, BH TI Calculation of third-order polarizabilities of large molecules. SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. SPELMAN COLL,ATLANTA,GA 30314. NASA,ALLIANCE NONLINEAR OPT,WASHINGTON,DC 20546. NSF,CTR THEORET STUDIES PHYS SYST,ARLINGTON,VA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD AUG 25 PY 1996 VL 212 BP 292 EP PHYS PN 2 PG 1 WC Chemistry, Multidisciplinary SC Chemistry GA VB009 UT WOS:A1996VB00900793 ER PT J AU Ribner, HS AF Ribner, HS TI Effects of jet flow on jet noise via an extension to the Lighthill model SO JOURNAL OF FLUID MECHANICS LA English DT Article AB The Lighthill formalism for jet noise prediction is extended to accommodate wave transport by the mean jet flow. The extended theory combines the simplicity of the Lighthill approach with the generality of the more complex Lilley approach. There is full allowance for 'flow-acoustic' effects: shielding, as well as the refractive 'cone of (relative) silence'. A source term expansion yields a convected wave equation that retains the basic Lighthill source term. This leads to a general formula for power spectral density emitted from unit volume as the Lighthill-based value multiplied by a squared 'normalized' Green's function. The Green's function, referred to a stationary point source, delineates the refraction dominated 'cone of silence'. The convective motion of the sources, with its powerful amplifying effect, also directional, is accounted for in the Lighthill factor. Source convection and wave convection are thereby decoupled, in contrast with the Lilley approach: this makes the physics more transparent. Moreover, the normalized Green's function appears to be near unity outside the 'cone of silence'. This greatly reduces the labour of calculation: the relatively simple Lighthill-based prediction may be used beyond the cone, with extension inside via the Green's function. The function is obtained either experimentally (injected 'point' source) or numerically (computational aeroacoustics). Approximation by unity seems adequate except near the cone and except when there are coaxial or shrouding jets: in that case the difference from unity will quantify the shielding effect. Further extension yields dipole and monopole source terms (cf Morfey, Mani, and others) when the mean flow possesses density gradients (e.g. hot jets). C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23671. RP Ribner, HS (reprint author), UNIV TORONTO,INST AEROSP STUDIES,DOWNSVIEW,ON M3H 5T6,CANADA. NR 72 TC 16 Z9 16 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD AUG 25 PY 1996 VL 321 BP 1 EP 24 DI 10.1017/S0022112096007628 PG 24 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA VH377 UT WOS:A1996VH37700001 ER PT J AU Ajello, JM Ciocca, M AF Ajello, JM Ciocca, M TI Fast nitrogen atoms from dissociative excitation of N-2 by electron impact SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID TRANSLATIONAL ENERGY-DISTRIBUTION; EXTREME ULTRAVIOLET EMISSION; CROSS-SECTIONS; EARTHS THERMOSPHERE; MEDIUM-RESOLUTION; PREDISSOCIATION; HYDROGEN; SPECTROMETER; SPECTROSCOPY; COLLISIONS AB The Doppler profiles of one of the fine structure lines of the N I (1200 Angstrom) g S-4(0)-P-4 multiplet and of the N II (1085 Angstrom) g P-3(0)-D-3 multiplet have been measured. Excitation of the multiplets is produced by electron impact dissociative excitation of N-2. The experimental line profiles are evaluated by fast Fourier transform (FFT) techniques and analysis of the profiles yields the kinetic energy distribution of fragments. The full width at half maximum (FWHM) of N I (1200 Angstrom) increases from 27 +/- 6 m Angstrom at 30 eV to 37 +/- 4 m Angstrom at 100 eV as the emission cross section of the dissociative ionization excitation process becomes more important relative to the dissociative excitation process. The FWHM of the N II (1085 Angstrom) line is 36 +/- 4 m Angstrom at 100 eV. For each multiplet the kinetic energy distribution function of each of the two fragment N atoms (ions) is much broader than thermal with a mean energy above 1.0 eV. The dissociation process with the largest cross section is predissociation and predominantly produces N atoms with kinetic energy distributions having mean energies above 0.5 eV. Dissociative processes can lead to a substantial escape flux of N I atoms from the satellites, Titan and Triton of the outer planets. RP Ajello, JM (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 46 TC 14 Z9 14 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD AUG 25 PY 1996 VL 101 IS E8 BP 18953 EP 18960 DI 10.1029/96JE01827 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA VE400 UT WOS:A1996VE40000006 ER PT J AU Haines, M Mehrotra, P AF Haines, M Mehrotra, P TI Special issue on multithreading for multiprocessors: Introduction SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Editorial Material C1 NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23681. RP Haines, M (reprint author), UNIV WYOMING,DEPT COMP SCI,LARAMIE,WY 82071, USA. NR 27 TC 0 Z9 0 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD AUG 25 PY 1996 VL 37 IS 1 BP 1 EP 4 DI 10.1006/jpdc.1996.0103 PG 4 WC Computer Science, Theory & Methods SC Computer Science GA VL778 UT WOS:A1996VL77800001 ER PT J AU Druyan, LM Lonergan, P Saloum, M AF Druyan, LM Lonergan, P Saloum, M TI African wave disturbances and precipitation at Niamey during July August 1987 and 1988 SO CLIMATE RESEARCH LA English DT Article DE African waves; Sahel; ECMWF analyses ID SQUALL LINES; ATLANTIC AB The contribution of African wave disturbances (AWD) to the interannual variability of precipitation in the Sahel is considered. Synoptic circumstances associated with the occurrence of precipitation at Niamey (Niger) during July-August 1987 and 1988 are investigated using European Center for Medium Range Weather Forecasts (ECMWF) gridded analyses and Niamey station observations of several meteorological variables. AWD are detected as oscillations in time series of 700 mb meridional winds and as inverted U-shaped cyclonic circulations on latitude-longitude analyses of the 700 mb wind field over West Africa, Spectral analyses of the time series indicate several prominent AWD periods with peaks ranging from 3 to 6 d, with somewhat different results for Niamey radiosonde data and the co-located ECMWF winds. Three passages of AWD at Niamey are examined in detail and the circumstances associated with ample precipitation during the first two are contrasted with the factors that led to a deficiency of rainfall during the third AWD. The study provides evidence that rainier seasons in the Sahel do not necessarily experience a greater number of AWD or even more intense AWD than drier summers. Occasional heavy precipitation can result from uplift driven by upper tropospheric divergence unrelated to AWD. On the other hand, AWD can provide an important trigger mechanism for convective rainfall during an otherwise dry spell. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. SCI SYST & APPLICAT INC,NEW YORK,NY 10025. DIRECT METEOROL NATL,NIAMEY,NIGER. RP Druyan, LM (reprint author), COLUMBIA UNIV,CTR CLIMATE SYST RES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 15 TC 14 Z9 14 U1 0 U2 0 PU INTER-RESEARCH PI OLDENDORF LUHE PA NORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANY SN 0936-577X J9 CLIMATE RES JI Clim. Res. PD AUG 22 PY 1996 VL 7 IS 1 BP 71 EP 83 DI 10.3354/cr007071 PG 13 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA VK432 UT WOS:A1996VK43200007 ER PT J AU Bogan, DJ Thorn, RP Nesbitt, FL Stief, LJ AF Bogan, DJ Thorn, RP Nesbitt, FL Stief, LJ TI Experimental 300 K measurement of the rate constant of the reaction OH+BrO-> products SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID ATMOSPHERIC BROMINE; KINETICS; 298-K AB The results reported herein are believed to be the first experimental measurements of the rate constant for the reaction OH + BrO --> products (eq 1), which was found to be (7.5 +/- 4.2) x 10(-11) cm(3) molecule(-1) s(-1) (2 sigma) at 300 K and 1 Torr. The mean value is 7 times larger than the estimate in the NASA stratospheric database, which currently finds widespread use to model the chemistry that controls stratospheric ozone concentrations. The reactant radicals were prepared in separate flow reactors and mixed in the main flow reactor, OH was prepared by F + H2O --> OH + HF, and BrO was prepared by passing dilute mixtures of He/Br-2/O-2 through a microwave discharge. The composition of the gas mixture was adjusted empirically to minimize the effluent concentration of Br-2. Beam-sampling mass spectrometry supplemented by chemical titration techniques was used to measure atom and radical concentrations. The rate constant for reaction 1 was obtained from a least-squares fit of the observed BrO concentrations as a function of time to a numerical model of relevant reactions. Known values were used for all other rate constants while k(1) was fitted. Just three reactions significantly affect the fitted value of k(1): OH + BrO --> Br + HO2 (eq 1a), OH + Br-2 --> HOBr + Br (eq 2), and BrO + BrO --> products (eq 6). The mechanism of reaction 1 is believed to be OH + BrO --> [HOOBr](#) --> Br + HO2, Delta H-R = -10 kcal mol(-1) (eq 1a) and OH + BrO --> [HOOBr](#) --> HBr + O-2, Delta H-R = -48 kcal mol(-1) (1b), where [HOOBr](#) denotes a short-lived vibrationally excited addition complex. It is argued that eq 1a is the predominant and perhaps exclusive product channel, with eq 1b hindered by a large activation energy for access to the HBr + O-2 products. The magnitude of k(1), approximately one-half of the gas kinetic limit, is attributed to the promotion of efficient spin-orbit mixing of singlet and tripler surfaces in the [HOOBr]# complex by the heavy Br atom. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. COPPIN STATE COLL,DEPT NAT SCI,BALTIMORE,MD 21216. CATHOLIC UNIV AMER,DEPT CHEM,WASHINGTON,DC 20064. NR 20 TC 28 Z9 28 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD AUG 22 PY 1996 VL 100 IS 34 BP 14383 EP 14389 DI 10.1021/jp9608077 PG 7 WC Chemistry, Physical SC Chemistry GA VD991 UT WOS:A1996VD99100016 ER PT J AU Oswalt, TD Smith, JA Wood, MA Hintzen, P AF Oswalt, TD Smith, JA Wood, MA Hintzen, P TI A lower limit of 9.5 Gyr on the age of the Galactic disk from the oldest white dwarf stars SO NATURE LA English DT Article ID LUMINOSITY FUNCTION; GLOBULAR-CLUSTERS; UNIVERSE; GALAXY; MASS; EVOLUTION; DISTANCES; MODELS AB WHITE dwarf stars represent the final evolutionary state for most main-sequence stars. They cool slowly enough that even the oldest white dwarfs are still observable in sufficiently deep surveys and they therefore provide a record of the age and star-formation history of the Local disk of the Milky Way(1-7)-and hence a useful constraint on the age of the Galaxy itself. Here we report the initial results of a very deep survey of white dwarfs, that avoids many of the problems associated with the incompleteness of earlier surveys. We use model age-luminosity relations to interpret the luminosity function of our sample of stars, and thus obtain a minimum age for the local Galactic disk of similar to 9.5 Gyr, Our results lend weight to an emerging picture of the evolutionary history of the Milky Way, in which the halo formed similar to 14-17 Gyr ago(8,9), followed by the bulge globular dusters similar to 12-14 Gyr ago(10), with a modest hiatus before the onset of star formation in the local disk similar to 10 Gyr ago. C1 UNIV NEVADA, DEPT PHYS, LAS VEGAS, NV 89154 USA. NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. CALIF STATE UNIV LONG BEACH, DEPT PHYS & ASTRON, LONG BEACH, CA 90840 USA. RP Oswalt, TD (reprint author), FLORIDA INST TECHNOL, DEPT PHYS & SPACE SCI, MELBOURNE, FL 32901 USA. NR 42 TC 169 Z9 169 U1 0 U2 3 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD AUG 22 PY 1996 VL 382 IS 6593 BP 692 EP 694 DI 10.1038/382692a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA VD333 UT WOS:A1996VD33300041 ER PT J AU Baskaran, S Stadler, PF Schuster, P AF Baskaran, S Stadler, PF Schuster, P TI Approximate scaling properties of RNA free energy landscapes SO JOURNAL OF THEORETICAL BIOLOGY LA English DT Article ID LONG-RANGE CORRELATION; SECONDARY STRUCTURES; FITNESS LANDSCAPES; 1/F NOISE; EVOLUTIONARY OPTIMIZATION; SEQUENCES; STATISTICS; KINETICS; SERIES; MODEL AB RNA free energy landscapes are analysed by means of ''time-series'' that are obtained from random walks restricted to excursion sets. The power spectra, the scaling of the jump size distribution, and the scaling of the curve length measured with different yard stick lengths are used to describe the structure of these ''time series''. Although they are stationary by construction, we find that their local behavior is consistent with both AR(I) and self-affine processes. Random walks confined to excursion sets (i.e., with the restriction that the fitness value exceeds a certain threshold at each step) exhibit essentially the same statistics as free random walks. We find that an AR(I) time series is in general approximately self-affine on timescales up to approximately the correlation length. We present an empirical relation between the correlation parameter rho of the AR(I) model and the exponents characterizing self-affinity. (C) 1996 Academic Press Limited C1 UNIV VIENNA, INST THEORET CHEM, A-1090 VIENNA, AUSTRIA. GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. SANTA FE INST, SANTA FE, NM 87501 USA. INST MOL BIOTECHNOL EV, JENA, GERMANY. RI Stadler, Peter F./L-7857-2015 OI Stadler, Peter F./0000-0002-5016-5191 NR 66 TC 8 Z9 8 U1 0 U2 1 PU ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-5193 EI 1095-8541 J9 J THEOR BIOL JI J. Theor. Biol. PD AUG 21 PY 1996 VL 181 IS 4 BP 299 EP 310 DI 10.1006/jtbi.1996.0132 PG 12 WC Biology; Mathematical & Computational Biology SC Life Sciences & Biomedicine - Other Topics; Mathematical & Computational Biology GA VJ773 UT WOS:A1996VJ77300001 PM 8949578 ER PT J AU Chudamani, S Spinhirne, JD Clarke, AD AF Chudamani, S Spinhirne, JD Clarke, AD TI Lidar aerosol backscatter cross sections in the 2-mu m near-infrared wavelength region SO APPLIED OPTICS LA English DT Article DE lidar; aerosol; backscatter; near infrared; particle counter ID FREE TROPOSPHERE AB Lidar backscatter cross-sectional measurements at 1.064, 0.532, and 1.54 mu m were acquired during November 1989 and May-June 1990 around the Pacific region by the NASA DC-8 aircraft as part of the Global Backscatter Experiment. The primary motivation for the Global Backscatter Experiment was the study of lidar backscatter cross sections for the development of a spaceborne wind-sensing lidar. Direct backscatter measurements obtained by the NASA Goddard Space Flight Center visible and infrared lidar are compared with backscatter cross sections calculated from aerosol size distributions obtained by particle counters. Results for one flight with pronounced aerosol layers in the upper troposphere southeast of Japan are presented. Because 2-mu m region wavelengths are possible candidates for a spaceborne wind-sensing lidar, the visible and infrared lidar backscatter cross sections at 1.064, 0.532, and 1.54 mu m are extrapolated to the 2-mu m region. The extrapolated 2-mu m cross sections are compared with lidar measurements at 9 mu m. A significant range in the ratio of 2-9-mu m backscatter cross sections is found, but a large number of points concentrate near ratios of three to ten. A large number of 1.064- and 1.54-mu m cross sections were binned to provide an estimate of backscatter for various percentiles for the flight. The ratio of the 50-percentile backscatter values at 1.064 and 1.54 mu m suggest a lambda(-1.9) to lambda(-3.0) wavelength dependence of aerosol backscatter cross section in the near infrared for the observational case. (C) 1996 Optical Society of America C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. UNIV HAWAII MANOA,DEPT OCEANOG,HONOLULU,HI 96822. RP Chudamani, S (reprint author), SCI SYST APPLICAT INC,LANHAM,MD 20706, USA. NR 16 TC 7 Z9 7 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1996 VL 35 IS 24 BP 4812 EP 4819 DI 10.1364/AO.35.004812 PG 8 WC Optics SC Optics GA VC320 UT WOS:A1996VC32000019 PM 21102906 ER PT J AU Tratt, DM Bowers, MS AF Tratt, DM Bowers, MS TI Optimization of coherent lidar performance with graded-reflectance transmitter resonator optics in the low equivalent Fresnel number regime SO APPLIED OPTICS LA English DT Article ID SUPER-GAUSSIAN MIRRORS; UNSTABLE RESONATORS; REFLECTIVITY MIRRORS; LASERS AB Using a diffractive eigenmode treatment to model the laser output we show that graded-reflectance resonator optics offer significant efficiency benefits over conventional hard-edge coupled unstable resonators in the context of coherent detection lidar applications. Extending previous research pertinent to the high equivalent Fresnel number regime, we have modeled the optimum performance of a notional super-Gaussian coupled cavity as a function of the key resonator parameters in the low equivalent Fresnel number (<3) regime. The findings from this study are applicable to the design of coherent lidar transmitters operated within this regime. (C) 1996 Optical Society of America C1 ACULIGHT CORP,BELLEVUE,WA 98005. RP Tratt, DM (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Tratt, David/A-7884-2009 OI Tratt, David/0000-0002-3942-6848 NR 16 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1996 VL 35 IS 24 BP 4820 EP 4826 DI 10.1364/AO.35.004820 PG 7 WC Optics SC Optics GA VC320 UT WOS:A1996VC32000020 PM 21102907 ER PT J AU McGuckin, BT Haner, DA Menzies, RT Esproles, C Brothers, AM AF McGuckin, BT Haner, DA Menzies, RT Esproles, C Brothers, AM TI Directional reflectance characterization facility and measurement methodology SO APPLIED OPTICS LA English DT Article ID CALIBRATION AB A precision reflectance characterization facility, constructed specifically for the measurement of the bidirectional reflectance properties of Spectralon panels planned for use as in-flight calibrators on the NASA Multiangle Imaging Spectroradiometer (MISR) instrument is described. The incident linearly polarized radiation is provided at three laser wavelengths: 442, 632.8, and 859.9 nm. Each beam is collimated when incident on the Spectralon. The illuminated area of the panel is viewed with a silicon photodetector that revolves around the panel (360 degrees) on a 30-cm boom extending from a common rotational axis. The reflected radiance detector signal is ratioed with the signal from a reference detector to the effect of amplitude instabilities in the laser sources. This and other measures adopted to reduce noise have resulted in a bidirectional reflection function (BRF) calibration facility with a measurement precision with regard to a BRF measurement of +/-0.002 at the 1 sigma confidence level. The Spectralon test piece panel is held in a computer-controlled three-axis rotational assembly capable of a full 360 degrees rotation in the horizontal plane and 90 degrees in the vertical. The angular positioning system has repeatability and resolution of 0.001 degrees. Design details and an outline of the measurement methodology are presented. (C) 1996 Optical Society of America C1 CALIF STATE POLYTECH UNIV POMONA,DEPT CHEM,POMONA,CA 91768. RP McGuckin, BT (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 14 Z9 15 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1996 VL 35 IS 24 BP 4827 EP 4834 DI 10.1364/AO.35.004827 PG 8 WC Optics SC Optics GA VC320 UT WOS:A1996VC32000021 PM 21102908 ER PT J AU Mishchenko, MI Travis, LD Macke, A AF Mishchenko, MI Travis, LD Macke, A TI Scattering of light by polydisperse, randomly oriented, finite circular cylinders SO APPLIED OPTICS LA English DT Article DE light scattering; nonspherical particles; depolarization; aerosols; remote sensing ID NONSPHERICAL TSCHEBYSCHEFF PARTICLES; AXIALLY-SYMMETRICAL PARTICLES; POLARIZED-LIGHT; SINGLE-SCATTERING; BACKSCATTERED FRACTION; PLANETARY-ATMOSPHERES; SPHEROIDAL PARTICLES; AEROSOL BACKSCATTER; MATRIX; DEPOLARIZATION AB We use the T-matrix method, as described by Mishchenko [Appl. Opt. 32, 4652 (1993)], to compute rigorously light scattering by finite circular cylinders in random orientation. First we discuss numerical aspects of T-matrix computations specific for finite cylinders and present results of benchmark computations for a simple cylinder model. Then we report results of extensive computations for polydisperse, randomly oriented cylinders with a refractive index of 1.53 + 0.008i, diameter-to-length ratios of 1/2, 1/1.4, 1, 1.4, and 2, and effective size parameters ranging from 0 to 25. These computations parallel our recent study of Light scattering by polydisperse, randomly oriented spheroids and are used to compare scattering properties of the two classes of simple convex particles. Despite the significant difference in shape between the two particle types (entirely smooth surface for spheroids and sharp rectangular edges for cylinders), the comparison shows rather small differences in the integral photometric characteristics (total optical cross sections, single-scattering albedo, and asymmetry parameter of the phase function) and the phase function. The general patterns of the other elements of the scattering matrix for cylinders and aspect-ratio-equivalent spheroids are also qualitatively similar, although noticeable quantitative differences can be found in some particular cases. In general, cylinders demonstrate much less shape dependence of the elements of the scattering matrix than do spheroids. Our computations show that, like spheroids and bispheres, cylinders with surface-equivalent radii smaller than a wavelength can strongly depolarize backscattered light, thus suggesting that backscattering depolarization for nonspherical particles cannot be universally explained by using only geometric-optics considerations. (C) 1996 Optical Society of America C1 COLUMBIA UNIV, DEPT APPL PHYS, NEW YORK, NY 10025 USA. RP NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Mishchenko, Michael/D-4426-2012 NR 52 TC 101 Z9 103 U1 2 U2 19 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD AUG 20 PY 1996 VL 35 IS 24 BP 4927 EP 4940 DI 10.1364/AO.35.004927 PG 14 WC Optics SC Optics GA VC320 UT WOS:A1996VC32000032 PM 21102919 ER PT J AU Dingus, BL Bertsch, DL Digel, SW Esposito, JA Fichtel, CE Fierro, JM Hartman, RC Hunter, SD Kanbach, G Kniffen, DA Lin, YC Mattox, JR MayerHasselwander, HA Michelson, PF vonMontigny, C Mukherjee, R Nolan, PL Schneid, E Sreekumar, P Thompson, DJ Willis, TD AF Dingus, BL Bertsch, DL Digel, SW Esposito, JA Fichtel, CE Fierro, JM Hartman, RC Hunter, SD Kanbach, G Kniffen, DA Lin, YC Mattox, JR MayerHasselwander, HA Michelson, PF vonMontigny, C Mukherjee, R Nolan, PL Schneid, E Sreekumar, P Thompson, DJ Willis, TD TI Egret observations of gamma rays from point sources with galactic latitude -30 degrees 15 keV) energy fluxes are single-peaked with pulse fractions of similar to 0.12 and similar to 0.16, respectively, but similar to 180 degrees different in phase. The Fe-line flux also exhibits a single peak pulse profile. Its pulse fraction is similar to 0.37, and its peak lags that of the PL peak by similar to 140 degrees. The PL (E > 15 keV) profile is attributed to a pencil-beam-like anisotropy in the emission and the TB profile to a fan-beam-like anisotropy with the condition that the sum of the spin axis inclination and the angle between the spin and magnetic dipole axes is less than 90 degrees. The PF component shows no significant pulse variation and is attributed to emission from the accretion disk. C1 MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. NR 31 TC 43 Z9 44 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1996 VL 467 IS 2 BP 811 EP 818 DI 10.1086/177655 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VD218 UT WOS:A1996VD21800032 ER PT J AU Dupree, AK Penn, MJ Jones, HP AF Dupree, AK Penn, MJ Jones, HP TI He I 10830 angstrom wing asymmetry in polar coronal holes: Evidence for radial outflows SO ASTROPHYSICAL JOURNAL LA English DT Article DE sun, chromosphere; sun, corona; sun, infrared; solar wind; stars, mass loss ID EXTREME-ULTRAVIOLET OBSERVATIONS; SOLAR TRANSITION REGION; FIELD; MASS; FLOW; LINE AB Imaging spectroscopy of the Sun, carried out across the the solar poles, yielded several thousand profiles of the He I 10830 Angstrom chromospheric absorption line with effective spatial pixels of 1.1 x 2 arcsec(2). Profiles of He I 10830 Angstrom show the relative blue-wing absorption is stronger in the coronal holes than in the quiet Sun, creating an asymmetric profile indicative of mass outflow. Within the coronal holes, blueshifted line wings are found where He I absorption is weak, corresponding to the center of supergranular cells. However, in the quiet Sun, there is no line wing shift in supergranular centers. Spatially compact regions of strong red-wing absorption also occur across the disk. Within the polar coronal holes, the amplitude of the wing shift shows a linear dependence with cos theta (where the angle theta is measured with respect to an outward normal to the Sun's surface), suggesting that a radial outflow occurs with a characteristic speed of similar to 8 km s(-1). These observations represent the first detection of systematic outflows near the chromosphere transition region interface that appear to mark the origin of the high-speed wind acceleration from the solar surface. C1 NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,TUCSON,AZ 85726. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP Dupree, AK (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. NR 34 TC 44 Z9 44 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1996 VL 467 IS 2 BP L121 EP & DI 10.1086/310215 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VD221 UT WOS:A1996VD22100021 ER PT J AU Foster, RS Waltman, EB Tavani, M Harmon, BA Zhang, SN Paciesas, WS Ghigo, FD AF Foster, RS Waltman, EB Tavani, M Harmon, BA Zhang, SN Paciesas, WS Ghigo, FD TI Radio and X-ray variability of the galactic superluminal source GRS 1915+105 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; radio continuum, stars; X-rays, stars ID 8.3 GHZ; CYGNUS-X-3; OUTBURSTS; GRS-1915+105; J1655-40; WATCH AB We report results of radio and hard X-ray monitoring observations of the Galactic superluminal X-ray source GRS 1915+105 carried out with the Green Bank Interferometer and the Burst and Transient Source Experiment during the period 1994 September through 1996 March. Both the radio and the hard X-ray light curves show a complex transient behavior. The radio emission monitored at 2.25 and 8.3 GHz is correlated with episodes of enhanced hard X-ray emission. A phenomenological classification of the radio emission indicates two distinct emission modes: plateau and flaring. Plateau radio emission is in general optically thick, with a flat-topped light curve showing a rapid onset and decrease of the flux density. The radio flaring state shows large radio flares that can increase in flux density by 2 orders of magnitude in less than 18 hr, followed by an optically thin exponential decay. These observed large radio flares are consistent with external propagation of plasmoids emitting synchrotron radiation. We comment on the significance of these results, and suggest a scenario for modeling the multiwavelength behavior of GRS 1915+105. C1 COLUMBIA UNIV,COLUMBIA ASTROPHYS LAB,NEW YORK,NY 10027. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. NATL RADIO ASTRON OBSERV,GREEN BANK,WV 24944. RP Foster, RS (reprint author), USN,RES LAB,REMOTE SENSING DIV,CODE 7210,WASHINGTON,DC 20375, USA. NR 27 TC 69 Z9 69 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1996 VL 467 IS 2 BP L81 EP L84 DI 10.1086/310199 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VD221 UT WOS:A1996VD22100011 ER PT J AU Geballe, TR Kulkarni, SR Woodward, CE Sloan, GC AF Geballe, TR Kulkarni, SR Woodward, CE Sloan, GC TI The near-infrared spectrum of the brown dwarf Gliese 229B SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared, general; infrared, stars; infrared, lines and bands; stars, individual (Gliese 229B); stars, low-mass, brown dwarfs AB A medium-resolution 1.0-2.5 mu m spectrum of the brown dwarf Gliese 229B has been obtained using the facility spectrometer CGS4 on the United Kingdom Infrared Telescope. In addition to the broad spectral structure seen in earlier low-resolution observations, the new spectrum reveals a large number of absorption lines, many of which can be identified with water vapor. Water and methane are both shown to be strong absorbers in the near-infrared spectrum of the object. Several spectral features in G1 229B that are attributable to methane match ones seen in reflection in the giant outer planets and, in particular, Titan. C1 UNIV WYOMING,DEPT PHYS & ASTRON,LARAMIE,WY 82071. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. CALTECH,PALOMAR OBSERV,PASADENA,CA 91125. RP Geballe, TR (reprint author), JOINT ASTRON CTR,660 N ALOHOKU PL,HILO,HI 96720, USA. NR 12 TC 51 Z9 51 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1996 VL 467 IS 2 BP L101 EP L104 DI 10.1086/310203 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VD221 UT WOS:A1996VD22100016 ER PT J AU Glinski, RJ Nuth, JA Reese, MD Sitko, ML AF Glinski, RJ Nuth, JA Reese, MD Sitko, ML TI Observation of the spin-forbidden Cameron bands of CO in the ultraviolet emission spectrum of the Red Rectangle SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; line, identification; molecular data; ultraviolet, general ID CARBON-MONOXIDE; SPECTROMETER EXPERIMENT; MOLECULAR-EMISSION; HD-44179; TRANSITIONS; RESOLUTION; RADIATION; FEATURES; SYSTEM AB The center of the biconical nebula known as the Red Rectangle has been observed by using the ultraviolet spectrographs aboard the Hubble Space Telescope. We report the observation of phosphorescence of the Cameron bands of CO (a 3 Pi-->X(1) Sigma(+)) between 1850 and 2600 Angstrom. These bands are seen for the first time outside of the solar system. The bands are about one-fifth as strong as the accompanying emission bands of the spin-allowed Fourth Positive system, A charged-particle impact excitation mechanism is suggested for the direct production of CO (a (3) Pi) from CO (X(1) Sigma(+)). The C-I (D-1-P-1(o)) line is observed at 1931 Angstrom, suggesting that a large amount of C-I(D-1) is also present. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTROCHEM BRANCH,GREENBELT,MD 20771. UNIV CINCINNATI,DEPT PHYS,CINCINNATI,OH 45221. RP Glinski, RJ (reprint author), TENNESSEE TECHNOL UNIV,DEPT CHEM,COOKEVILLE,TN 38505, USA. RI Nuth, Joseph/E-7085-2012 NR 42 TC 15 Z9 15 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1996 VL 467 IS 2 BP L109 EP L112 DI 10.1086/310205 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VD221 UT WOS:A1996VD22100018 ER PT J AU Hogg, DW Blandford, R Kundic, T Fassnacht, CD Malhotra, S AF Hogg, DW Blandford, R Kundic, T Fassnacht, CD Malhotra, S TI A candidate gravitational lens in the hubble deep field SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, individual (HDF J123652+621227,HDF 5123656+621221); gravitational lensing ID SPACE-TELESCOPE; COSMOLOGICAL CONSTANT; GALAXIES; REDSHIFTS; COUNTS; NUMBER AB The discovery of HDF J123652+621227, a candidate gravitational lens in the Hubble Deep Field, is reported. This lens may be multiply imaging several optical sources at different redshifts. If follow-up spectroscopy of the lens and the brightest image confirms this hypothesis, observations of this system alone can be used to obtain an estimate of the redshift distribution at extremely faint flux levels. C1 CALTECH,DEPT ASTRON,PASADENA,CA 91125. CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. NASA,JET PROPULS LAB,WASHINGTON,DC 20546. RP Hogg, DW (reprint author), CALTECH,MAIL CODE 130-33,PASADENA,CA 91125, USA. OI Hogg, David/0000-0003-2866-9403 NR 27 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 20 PY 1996 VL 467 IS 2 BP L73 EP & DI 10.1086/310213 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VD221 UT WOS:A1996VD22100009 ER PT J AU Chin, M Jacob, DJ Gardner, GM ForemanFowler, MS Spiro, PA Savoie, DL AF Chin, M Jacob, DJ Gardner, GM ForemanFowler, MS Spiro, PA Savoie, DL TI A global three-dimensional model of tropospheric sulfate SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Review ID BIOGENIC SULFUR EMISSIONS; MARINE BOUNDARY-LAYER; SEA-SALT SULFATE; NORTHEAST PACIFIC-OCEAN; TROPICAL SOUTH-ATLANTIC; DIMETHYL SULFIDE; DRY DEPOSITION; VERTICAL-DISTRIBUTION; AMERICAN-SAMOA; AEROSOL IONS AB A three-dimensional model is used to simulate the global tropospheric distributions of dimethylsulfide (DMS), SO2, SO42-, and methanesulfonic acid(MSA). The model uses meteorological input from a general circulation model (GCM) developed at the Goddard Institute of Space Studies (GISS) with 4 degrees x 5 degrees horizontal resolution, nine layers in the vertical, and a time resolution of 4 hours. Model results are compared with observations from surface sites, ships, and aircraft. The model reproduces generally to within 30% the observed SO2 and SO42- concentrations over the United States and Europe; these concentrations are highly sensitive to the supply of H2O2 as an in-cloud SO2 oxidant. Sulfate concentrations and wet deposition fluxes observed at remote marine sites can be accounted for using a global DMS source of 22 Tg S yr(-1) in the model. However, this source overestimates DMS air concentrations by a factor of 2 unless we assume the presence of another DMS oxidant besides OH and NO3. Inclusion of another DMS oxidant in our model also improves the simulation of the MSA to SO42- concentration ratio in marine air. Simulated SO42- concentrations in the northern hemispheric free troposphere are much lower than in previous global models and are more consistent with the few observations available. The difference reflects in part our accounting of efficient scavenging of SO2 and SO42- in wet convective updrafts. Global mean tropospheric lifetimes computed in our model are 1.0 days for DMS, 1.2 days for SO2, 3.9 days for SO42-, and 6.2 days for MSA. Fossil fuel combustion and industrial activities represent 68% of global non-sea-salt sulfur emissions. About 50% of SO2 globally is converted to SO42- aerosol (principally by in-cloud oxidation) while the remainder is removed by deposition (30% by dry, 20% by wet). In-cloud oxidation of SO2 represents 85% of the global SO42- source. C1 UNIV COLORADO, PROGRAM ATOMOSPHER & OCEAN SCI, BOULDER, CO 80307 USA. HARVARD UNIV, DIV ENGN & APPL SCI, CAMBRIDGE, MA 02138 USA. HARVARD UNIV, DEPT EARTH & PLANETARY SCI, CAMBRIDGE, MA 02138 USA. UNIV MIAMI, ROSENSTIEL SCH MARINE & ATMOSPHER SCI, DIV MARINE & ATMOSPHER CHEM, MIAMI, FL 33149 USA. UNIV UTAH, DEPT MATH, SALT LAKE CITY, UT 84112 USA. HARVARD UNIV, DIV APPL SCI, CAMBRIDGE, MA 02138 USA. RP Chin, M (reprint author), NASA, GODDARD SPACE FLIGHT CTR, USRA, CODE 916, GREENBELT, MD 20771 USA. RI Chin, Mian/J-8354-2012 NR 117 TC 232 Z9 234 U1 2 U2 30 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 20 PY 1996 VL 101 IS D13 BP 18667 EP 18690 DI 10.1029/96JD01221 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VD227 UT WOS:A1996VD22700011 ER PT J AU Chin, M Jacob, DJ AF Chin, M Jacob, DJ TI Anthropogenic and natural contributions to tropospheric sulfate: A global model analysis SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SULFUR-DIOXIDE; AEROSOLS; ATMOSPHERE; DEPOSITION; TRANSPORT; PB-210; OZONE; OCEAN; TIME; OH AB A global three-dimensional model is used to examine the export of anthropogenic sulfur from northern midlatitude continents and to assess the relative importance of anthropogenic and natural sources to sulfate levels in different regions of the troposphere. Model results indicate that about 40% of the anthropogenic sulfur emitted in the United States, Europe, or eastern Asia is exported out of the continental boundary layer of these regions; the rest is removed within the regions, primarily by dry deposition of SO2 and wet deposition of SO42-. Export is relatively more efficient in summer than in winter. There is little nonlinearity between the magnitude of sulfur emissions in the northern midlatitude continents and the export of this sulfur to the global atmosphere. Anthropogenic influence on SO42- decreases rapidly with altitude because of efficient scavenging of SO2 and SO42- in deep convective updrafts. Thus it is found that anthropogenic influence accounts on average for less than 20% of SO42- anywhere in the upper troposphere. The main source of SO42- in the tropical upper troposphere in the model is from biogenic dimethylsulfide (DMS) pumped in deep convective events. Volcanic emissions account for 20-40% of SO42- in much of the middle troposphere and for up to 80% over the North Pacific; they also represent a major contributor to SO42- in the upper troposphere at high latitudes. On a global scale, it is estimated that anthropogenic, biogenic, and volcanic emissions account for 70%, 23%, and 7%, respectively, of the global sulfur source, but that they account for 37%, 42%, and 18%, respectively, of the global column of atmospheric SO42-. The disproportionality between source and column contribution reflects the rapid deposition of anthropogenic SO2 and SO42- at low altitudes. It thus appears that the anthropogenic contribution to the SO42- aerosol optical depth is much less than would be expected simply on the basis of emissions. C1 HARVARD UNIV, DIV ENGN & APPL SCI, CAMBRIDGE, MA 02138 USA. HARVARD UNIV, DEPT EARTH & PLANETARY SCI, CAMBRIDGE, MA 02138 USA. HARVARD UNIV, DIV APPL SCI, CAMBRIDGE, MA 02138 USA. RP Chin, M (reprint author), NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, CODE 916, GREENBELT, MD 20771 USA. RI Chin, Mian/J-8354-2012 NR 29 TC 136 Z9 140 U1 2 U2 26 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 20 PY 1996 VL 101 IS D13 BP 18691 EP 18699 DI 10.1029/96JD01222 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VD227 UT WOS:A1996VD22700012 ER PT J AU Russell, PB Livingston, JM Pueschel, RF Bauman, JJ Pollack, JB Brooks, SL Hamill, P Thomason, LW Stowe, LL Deshler, T Dutton, EG Bergstrom, RW AF Russell, PB Livingston, JM Pueschel, RF Bauman, JJ Pollack, JB Brooks, SL Hamill, P Thomason, LW Stowe, LL Deshler, T Dutton, EG Bergstrom, RW TI Global to microscale evolution of the Pinatubo volcanic aerosol derived from diverse measurements and analyses SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Review ID ARCTIC STRATOSPHERIC EXPEDITION; MOUNT-PINATUBO; MT-PINATUBO; SULFURIC-ACID; OPTICAL DEPTH; SIZE DISTRIBUTION; II MEASUREMENTS; TROPICAL OZONE; EL-CHICHON; AVHRR DATA AB We assemble data on the Pinatubo aerosol from space, air, and ground measurements, develop a composite picture, and assess the consistency and uncertainties of measurement and retrieval techniques. Satellite infrared spectroscopy, particle morphology, and evaporation temperature measurements agree with theoretical calculations in showing a dominant composition of H2SO4-H2O mixture, with H2SO4 weight fraction of 65-80% for most stratospheric temperatures and humidities. Important exceptions are (i) volcanic ash, present at all heights initially and just above the tropopause until at least March 1992, and (2) much smaller H2SO4 fractions at the low temperatures of high-latitude winters and the tropical tropopause. Laboratory spectroscopy and calculations yield wavelength- and temperature-dependent refractive indices for the H2SO4-H2O droplets. These permit derivation of particle size information from measured optical depth spectra, for comparison to impactor and optical-counter measurements. All three techniques paint a generally consistent picture of the evolution of R(eff), the effective radius. In the first month after the eruption, although particle numbers increased greatly, R(eff) outside the tropical core was similar to preeruption values of similar to 0.1 to 0.2 mu m, because numbers of both small (r<0.2 mu m) and large (r>0.6 mu m) particles increased. In the next 3-6 months, extracore R(eff) increased to similar to 0.5 mu m, reflecting particle growth through condensation and coagulation. Most data show that R(eff) continued to increase for similar to 1 year after the eruption. R(eff) values up to 0.6-0.8 mu m or more are consistent with 0.38-1 mu m optical depth spectra in middle to late 1992 and even later. However, in this period, values from in situ measurements are somewhat less. The difference might reflect in situ undersampling of the very few largest particles, insensitivity of optical depth spectra to the smallest particles, or the inability of flat spectra to place an upper limit on particle size. Optical depth spectra extending to wavelengths lambda>1 mu m are required to better constrain R(eff), especially for R(eff)>0.4 mu m. Extinction spectra computed from in situ size distributions are consistent with optical depth measurements; both show initial spectra with lambda(max)less than or equal to 0.42 mu m, thereafter increasing to 0.78 less than or equal to lambda(max)less than or equal to 1 mu m. Not until 1993 do spectra begin to show a clear return to the preeruption signature of lambda(max)less than or equal to 0.42 mu m. The twin signatures of large R(eff) (>0.3 mu m) and relatively flat extinction spectra (0.4-1 mu m) are among the longest-lived indicators of Pinatubo volcanic influence. They persist for years after the peaks in number, mass, surface area, and optical depth at all wavelengths less than or equal to 1 mu m. This coupled evolution in particle size distribution and optical depth spectra helps explain the relationship between global maps of 0.5- and 1.0-mu m optical depth derived from the Advanced Very High Resolution Radiometer (AVHRR) and Stratospheric Aerosol and Gas Experiment (SAGE) satellite sensors. However, there are important differences between the AVHRR and SAGE midvisible optical thickness products. We discuss possible reasons for these differences and how they might be resolved. C1 SUNY STONY BROOK, STONY BROOK, NY 11794 USA. BAY AREA ENVIRONM RES INST, SAN FRANCISCO, CA 94122 USA. SYNERNET INC, FREMONT, CA 94538 USA. UNIV WYOMING, DEPT PHYS & ASTRON, LARAMIE, WY 82071 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. SAN JOSE STATE UNIV, DEPT PHYS, SAN JOSE, CA 95192 USA. SRI INT, MENLO PK, CA 94025 USA. NOAA, NESDIS, CAMP SPRINGS, MD 20746 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. RP NASA, AMES RES CTR, MAIL STOP 245-5, MOFFETT FIELD, CA 94035 USA. OI Thomason, Larry/0000-0002-1902-0840 NR 107 TC 149 Z9 155 U1 2 U2 20 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 AUG 20 PY 1996 VL 101 IS D13 BP 18745 EP 18763 DI 10.1029/96JD01162 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VD227 UT WOS:A1996VD22700017 ER PT J AU Bhartia, PK McPeters, RD Mateer, CL Flynn, LE Wellemeyer, C AF Bhartia, PK McPeters, RD Mateer, CL Flynn, LE Wellemeyer, C TI Algorithm for the estimation of vertical ozone profiles from the backscattered ultraviolet technique SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MAPPING SPECTROMETER; SATELLITE; CALIBRATION; TRENDS; SSBUV; SBUV AB An implementation of the optimal estimation scheme ro obtain vertical ozone profiles from satellite measurements of backscattered solar ultraviolet (buv) radiation is described. This algorithm (Version 6.0) has been used to produce a 15-year data set of global ozone profiles from Nimbus 7 SBUV, NOAA 11 SBUV/2, and Space Shuttle SSBUV instruments. A detailed discussion of the information content of the measurement is presented. Using high vertical resolution ozone profiles from the SAGE II experiment as ''truth'' profiles, it is shown that the buv technique can capture short-term variabilities of ozone in 5-km vertical layers, between 0.3 mbar and 100 mbar, with a precision of 5-15%. However, outside the 1-20 mbar range, buv-derived results are heavily influenced by a priori assumptions. To minimize this influence, it is recommended that the studies of long-term trends using buv data be restricted to 1-20 mbar range. Outside this range, only the column amounts of ozone between 20 mbar and surface, and above 1 mbar, can be considered relatively free of a priori assumptions. C1 SOFTWARE CORP AMER, LANHAM, MD 20706 USA. HUGHES STX CORP, GREENBELT, MD 20770 USA. RP Bhartia, PK (reprint author), NASA, GODDARD SPACE FLIGHT CTR, MAIL CODE 916, GREENBELT, MD 20771 USA. RI Flynn, Lawrence/B-6321-2009; McPeters, Richard/G-4955-2013; Bhartia, Pawan/A-4209-2016 OI Flynn, Lawrence/0000-0001-6856-2614; McPeters, Richard/0000-0002-8926-8462; Bhartia, Pawan/0000-0001-8307-9137 NR 44 TC 164 Z9 169 U1 0 U2 10 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 20 PY 1996 VL 101 IS D13 BP 18793 EP 18806 DI 10.1029/96JD01165 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VD227 UT WOS:A1996VD22700021 ER PT J AU Santee, ML Froidevaux, L Manney, GL Read, WG Waters, JW Chipperfield, MP Roche, AE Kumer, JB Mergenthaler, JL Russell, JM AF Santee, ML Froidevaux, L Manney, GL Read, WG Waters, JW Chipperfield, MP Roche, AE Kumer, JB Mergenthaler, JL Russell, JM TI Chlorine deactivation in the lower stratospheric polar regions during late winter: Results from UARS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; ANTARCTIC OZONE EXPERIMENT; TOTAL REACTIVE NITROGEN; MICROWAVE LIMB SOUNDER; 1988/89 ARCTIC WINTER; TRACE GASES; INTERHEMISPHERIC DIFFERENCES; AIRBORNE MEASUREMENTS; CHEMICAL DEPLETION; HEMISPHERE WINTER AB Recovery from enhanced chlorine conditions in the lower stratospheric polar regions of both hemispheres is investigated using data from the Upper Atmosphere Research Satellite (UARS). Microwave Limb Sounder (MLS) measurements of ClO within the polar vortices are used to infer ClOx (ClO+2Cl(2)O(2)) abundances that are then correlated with simultaneous Cryogenic Limb Array Etalon Spectrometer (CLAES) measurements of ClONO2 and Halogen Occultation Experiment (HALOE) measurements of HCl obtained starting within 5 days of the end of the MLS and CLAES high-latitude observing periods in each hemisphere. Time series of vortex-averaged mixing ratios are calculated on two potential temperature surfaces (585 K and 465 K) in the lower stratosphere for approximately month-long intervals during late winter: August 17 - September 17, 1992, in the southern hemisphere and February 12 - March 16, 1993, in the northern hemisphere. The observed mixing ratios are adjusted for the effects of vertical transport using diabatic vertical velocities estimated from CLAES tracer data. In the northern hemisphere, the decrease in ClOx is balanced on both surfaces by an increase in ClONO2. In the southern hemisphere, continuing polar stratospheric cloud activity prevents ClO from undergoing sustained decline until about September 3. In contrast to the northern hemisphere, there is no significant chemical change in vortex-averaged ClONO2 at 465 K, and there is an apparent decrease in ClONO2 at 585 K, even after the enhanced ClO abundances have started to recede. Results from the SLIMCAT chemical transport model [Chipperfield et al., this issue] initialized with UARS data and run with OH + ClO --> HCl O-2 as an 8% channel suggest that the primary recovery product in the south during this time period is not ClONO2, but HCl. HALOE HCl mixing ratios are extrapolated back to the time of the MLS and CLAES data. At 585 K, the chlorine budget can be made to balance by extrapolating HCl back to a value of 0.6 parts per billion by volume (ppbv) at the beginning of the study period; at 465 K, the contribution from extrapolated HCl is not sufficient to offset the loss in ClOx, and there is a slight imbalance between the decrease in reactive chlorine and the change in chlorine reservoirs. The difficulty in closing the chlorine budget in the southern hemisphere may arise from complications caused by ongoing activation, incomplete photochemical assumptions, and/or inadequate data quality. C1 UNIV CAMBRIDGE, DEPT CHEM, CAMBRIDGE CB2 1TN, ENGLAND. LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94061 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. RP Santee, ML (reprint author), CALTECH, JET PROP LAB, MAIL STOP 183-701, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Chipperfield, Martyn/H-6359-2013 OI Chipperfield, Martyn/0000-0002-6803-4149 NR 94 TC 48 Z9 48 U1 1 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 20 PY 1996 VL 101 IS D13 BP 18835 EP 18859 DI 10.1029/96JD00580 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VD227 UT WOS:A1996VD22700024 ER PT J AU Chipperfield, MP Santee, ML Froidevaux, L Manney, GL Read, WG Waters, JW Roche, AE Russell, JM AF Chipperfield, MP Santee, ML Froidevaux, L Manney, GL Read, WG Waters, JW Roche, AE Russell, JM TI Analysis of UARS data in the southern polar vortex in September 1992 using a chemical transport model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID INTERHEMISPHERIC DIFFERENCES; LOWER STRATOSPHERE; WINTER; OZONE; CLO; VARIABILITY; HNO3; HCL; HO2 AB We have used a new, isentropic-coordinate three-dimensional chemical transport model to investigate the decay of ClO and evolution of other species in the Antarctic polar vortex during September 1992. The model simulations cover the same southern hemisphere period studied in a companion data paper by Santee et al. [this issue]. The model is initialized using the available data from the Microwave Limb Sounder (MLS) and Cryogenic Limb Array Etalon Spectrometer (CLAES) on the Upper Atmosphere Research Satellite (UARS). During the model initialization chemical inconsistencies in the UARS data became evident. Fields of odd nitrogen (NOy) derived from CLAES N2O underestimated the sum of the direct observations of the major NOy species. Results from the model integrations at 465 K and 585 K are sampled in the same way as the various UARS instruments and compared to the observations both directly and by considering average quantities in the inner and edge vortex regions. Sampling the observed species ill the same way as the UARS instruments is important in removing any spurious trends due, for example, to changing solar zenith angle. While the model can reproduce the magnitude of the MLS ClO observations at 585 K, this is not possible at 465 K. The model partitions too much ClO into Cl2O2 to reproduce the observed ClO which is around 2.0 parts per billion by volume (ppbv) averaged within the polar vortex. The model also underestimates CLAES ClONO2 in the inner vortex at 465 K due to heterogeneous processing. The observations require that effectively all of the inorganic chlorine is in the form of ClO and C1ONO2 in the inner vortex at this altitude. In the basic model run, the decay of ClO produces ClONO2 which is not observed by CLAES. Our results indicate the potential importance of the speculative reaction between OH and ClO producing HCl for the recovery of HCl in the Antarctic spring. By including this reaction, the decay of model ClO into HCl is enhanced, yielding better agreement with HCl data from the Halogen Occultation Experiment (HALOE) data. Similar results can also be obtained by including the reaction between HO2 and ClO to produce HCl with a 3% channel. The model generally reproduces the observed O-3 destruction during September. The most significant discrepancy for O-3 is in the inner vortex at 465 K where the model underestimates the observed O-3 loss rate, especially when the effects of vertical motion are included. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94304 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. RP Chipperfield, MP (reprint author), DEPT CHEM, LENSFIELD RD, CAMBRIDGE CB2 1EW, ENGLAND. RI Chipperfield, Martyn/H-6359-2013 OI Chipperfield, Martyn/0000-0002-6803-4149 NR 39 TC 80 Z9 80 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD AUG 20 PY 1996 VL 101 IS D13 BP 18861 EP 18881 DI 10.1029/96JD00936 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VD227 UT WOS:A1996VD22700025 ER PT J AU Hummer, G Garde, S Garcia, AE Pohorille, A Pratt, LR AF Hummer, G Garde, S Garcia, AE Pohorille, A Pratt, LR TI An information theory model of hydrophobic interactions SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article DE solvation; hydrophobic effects; biomolecule solution structure ID SOLVATION FREE-ENERGIES; STATISTICAL MECHANICAL FORMULATION; PROTEIN-FOLDING THERMODYNAMICS; MOLECULAR RECOGNITION; COMPUTER-SIMULATIONS; GLOBULAR-PROTEINS; SIZE DEPENDENCE; SOLVENT MODEL; BOUND WATER; HYDRATION AB A molecular model of poorly understood hydrophobic effects is heuristically developed using the methods of information theory, Because primitive hydrophobic effects can be tied to the probability of observing a molecular-sized cavity in the solvent, the probability distribution of the number of solvent centers in a cavity volume is modeled on the basis of the two moments available from the density and radial distribution of oxygen atoms in liquid water. The modeled distribution then yields the probability that no solvent centers are found in the cavity volume, This model is shown to account quantitatively for the central hydrophobic phenomena of cavity formation and association of inert gas solutes. The connection of information theory to statistical thermodynamics provides a basis for clarification of hydrophobic effects. The simplicity and flexibility of the approach suggest that it should permit applications to conformational equilibria of nonpolar solutes and hydrophobic residues in biopolymers. C1 LOS ALAMOS NATL LAB,DIV THEORET,LOS ALAMOS,NM 87545. UNIV CALIF SAN FRANCISCO,DEPT PHARMACEUT CHEM,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Garde, Shekhar/C-3060-2008; Pratt, Lawrence/H-7955-2012; Hummer, Gerhard/A-2546-2013 OI Pratt, Lawrence/0000-0003-2351-7451; Hummer, Gerhard/0000-0001-7768-746X NR 79 TC 414 Z9 418 U1 6 U2 73 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD AUG 20 PY 1996 VL 93 IS 17 BP 8951 EP 8955 DI 10.1073/pnas.93.17.8951 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA VD434 UT WOS:A1996VD43400031 PM 11607700 ER PT J AU Shirley, DL AF Shirley, DL TI Mars resolve underway SO AVIATION WEEK & SPACE TECHNOLOGY LA English DT Letter RP Shirley, DL (reprint author), CALTECH,JET PROP LAB,MARS EXPLORAT PROGRAM,PASADENA,CA 91109, USA. NR 1 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 SN 0005-2175 J9 AVIAT WEEK SPACE TEC JI Aviat. Week Space Technol. PD AUG 19 PY 1996 VL 145 IS 8 BP 6 EP 6 PG 1 WC Engineering, Aerospace SC Engineering GA VD251 UT WOS:A1996VD25100001 ER PT J AU Kanik, I AF Kanik, I TI Far ultraviolet emission spectrum of xenon induced by electron impact at 100 eV SO CHEMICAL PHYSICS LETTERS LA English DT Article ID EXTREME-ULTRAVIOLET; CROSS-SECTIONS; MEDIUM-RESOLUTION; EXCITATION; CALIBRATION; NE; AR AB The FUV emission spectrum of xenon, which contains five emission lines at 117.04, 119.2, 125.1, 129.56 and 146.96 nm over the wavelength range 110-160 nm, produced by electron impact at 100 eV is presented. The measurements were obtained under near-optically-thin conditions at a spectral resolution of 1.0 nm FWHM. In addition, the absolute emission cross sections at 100 eV electron impact energy were obtained for these emission lines. Most prominent features of the FUV spectrum are the Xe I lines at 146.9 and 119.2 nm with the emission cross sections of 58.5 x 10(-18) cm(2) and 45.0 x 10(-18) cm(2), respectively, with an uncertainty of 27%. RP Kanik, I (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 21 TC 2 Z9 2 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 AUG 16 PY 1996 VL 258 IS 3-4 BP 455 EP 459 DI 10.1016/0009-2614(96)00688-4 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA VC071 UT WOS:A1996VC07100022 ER PT J AU McKay, DS Gibson, EK ThomasKeprta, KL Vali, H Romanek, CS Clemett, SJ Chillier, XDF Maechling, CR Zare, RN AF McKay, DS Gibson, EK ThomasKeprta, KL Vali, H Romanek, CS Clemett, SJ Chillier, XDF Maechling, CR Zare, RN TI Search for past life on Mars: Possible relic biogenic activity in Martian meteorite ALH84001 SO SCIENCE LA English DT Article ID POLYCYCLIC AROMATIC-HYDROCARBONS; RECENT LAKE-SEDIMENTS; SNC METEORITES; MAGNETOTACTIC BACTERIA; ISOTOPIC COMPOSITION; WEATHERING PRODUCTS; MURCHISON METEORITE; SINGLE-DOMAIN; CARBON; MAGNETITE AB Fresh fracture surfaces of the martian meteorite ALH84001 contain abundant polycyclic aromatic hydrocarbons (PAHs). These fresh fracture surfaces also display carbonate globules. Contamination studies suggest that the PAHs are indigenous to the meteorite. High-resolution scanning and transmission electron microscopy study of surface textures and internal structures of selected carbonate globules show that the globules contain fine-grained, secondary phases of single-domain magnetite and Fe-sulfides. The carbonate globules are similar in texture and size to some terrestrial bacterially induced carbonate precipitates. Although inorganic formation is possible, formation of the globules by biogenic processes could explain many of the observed features, including the PAHs. The PAHs, the carbonate globules, and their associated secondary mineral phases and textures could thus be fossil remains of a past martian biota. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NASA,HOUSTON,TX 77058. MCGILL UNIV,DEPT EARTH & PLANETARY SCI,MONTREAL,PQ H3A 2A7,CANADA. UNIV GEORGIA,SAVANNAH RIVER ECOL LAB,AIKEN,SC 29802. STANFORD UNIV,DEPT CHEM,STANFORD,CA 94305. RP McKay, DS (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,MAIL CODE SN,HOUSTON,TX 77058, USA. RI Zare, Richard/A-8410-2009; Vali, Hojatollah/F-3511-2012; Wright, Dawn/A-4518-2011 OI Vali, Hojatollah/0000-0003-3464-9943; Wright, Dawn/0000-0002-2997-7611 NR 87 TC 1058 Z9 1099 U1 54 U2 311 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 16 PY 1996 VL 273 IS 5277 BP 924 EP 930 DI 10.1126/science.273.5277.924 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA VC670 UT WOS:A1996VC67000052 PM 8688069 ER PT J AU Larson, DE Lin, RP McFadden, JP Ergun, RE Carlson, CW Anderson, KA Phan, TD McCarthy, MP Parks, GK Reme, H Bosqued, JM dUston, C Sanderson, TR Wenzel, KP Lepping, RP AF Larson, DE Lin, RP McFadden, JP Ergun, RE Carlson, CW Anderson, KA Phan, TD McCarthy, MP Parks, GK Reme, H Bosqued, JM dUston, C Sanderson, TR Wenzel, KP Lepping, RP TI Probing the Earth's bow shock with upstream electrons SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PERPENDICULAR COLLISIONLESS SHOCKS; SOLAR-WIND ELECTRONS; ACCELERATION; DISTRIBUTIONS AB We present detailed measurements from the WIND 3D Plasma and Energetic Particle experiment of electron distributions in the deep foreshock, well away from the foreshock boundaries. Both electrons escaping from the magnetosheath and solar wind electrons reflected by the strong magnetic field of the shock are observed. The loss cone angle that separates the reflected electrons from the escaping magnetosheath electrons can be determined as a function of electron energy. At lower energies, the loss cone angle increases because the cross-shock potential tends to pull electrons into the magnetosheath. The loss cone angle is typically less than or equal to 30 degrees at energies greater than or equal to 100 eV, corresponding to peak shock magnetic field to local magnetic field ratio of greater than or equal to 5, while the loss cone variation with energy gives typical shock potentials of similar to 85 V. Thus the measurements of back-streaming foreshock electrons can be used as a tool to remotely probe the characteristics of the bow shock. C1 UNIV WASHINGTON, GEOPHYS PROGRAM, SEATTLE, WA USA. CTR ETUD SPATIALE RAYONNEMENTS, TOULOUSE, FRANCE. EUROPEAN SPACE AGCY, ESTEC, DEPT SPACE SCI, NL-2200 AG NOORDWIJK, NETHERLANDS. NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. UNIV CALIF BERKELEY, DEPT PHYS, BERKELEY, CA 94720 USA. RP UNIV CALIF BERKELEY, SPACE SCI LAB, BERKELEY, CA 94720 USA. NR 15 TC 18 Z9 18 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 AUG 15 PY 1996 VL 23 IS 17 BP 2203 EP 2206 DI 10.1029/96GL02382 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600001 ER PT J AU Kaye, JA Miller, TL AF Kaye, JA Miller, TL TI The ATLAS series of shuttle missions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The ATLAS space shuttle missions were conducted in March 1992, April 1993, and November 1994. The ATLAS payload and companion instruments made measurements of solar irradiance and middle atmospheric temperatures and trace gas concentrations. The solar irradiance measurements included total and spectrally resolved solar irradiance. The atmospheric measurements included microwave, infrared, and ultraviolet limb sounding, nadir ultraviolet backscatter, and solar occultation techniques. This paper introduces a special section in this issue of Geophysical Research Letters. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,EARTH SYST SCI DIV,HUNTSVILLE,AL 35812. RP Kaye, JA (reprint author), NASA,OFF MISS PLANET EARTH,WASHINGTON,DC 20546, USA. NR 21 TC 45 Z9 45 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2285 EP 2288 DI 10.1029/96GL02228 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600022 ER PT J AU Cebula, RP Thuillier, GO VanHoosier, ME Hilsenrath, E Herse, M Brueckner, GE Simon, PC AF Cebula, RP Thuillier, GO VanHoosier, ME Hilsenrath, E Herse, M Brueckner, GE Simon, PC TI Observations of the solar irradiance in the 200-350 nm interval during the ATLAS-1 mission: A comparison among three sets of measurements - SSBUV, SOLSPEC, and SUSIM SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CALIBRATION; BOARD AB The SOLSPEC, SSBUV, and SUSIM spectrometers simultaneously observed the solar spectral irradiance during the ATLAS-I mission flown on board the Space Shuttle Atlantis in March 1992. The three instruments use different methods and means of absolute calibration and were each calibrated preflight and postflight. The three data sets are reported from 200 to 350 nm at 1.1 nm resolution. The method of comparing the three independent data sets is discussed. The importance of a common, precise wavelength scale is shown when comparing the data in wavelength regions of strong Fraunhofer lines. The agreement among the solar irradiance measurements is better than +/-5%. The fact that the calibrations of the three instruments were based on three independent standards provides confidence that the absolute solar spectral irradiance in the range 200-350 nm is now known with an accuracy better than +/-5%. The mean ATLAS-I solar spectrum is compared with simultaneous solar observations from the UARS SOLSTICE and UARS SUSIM instruments. The two mean solar spectra agree to within +/-3%. C1 USN,RES LAB,WASHINGTON,DC 20375. CNRS,SERV AERON,F-91371 VERRIERES BUISSON,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. INST AERON SPATIALE BELGIQUE,B-1180 BRUSSELS,BELGIUM. RP Cebula, RP (reprint author), HUGHES STX CORP,7701 GREENBELT RD,GREENBELT,MD 20770, USA. NR 19 TC 63 Z9 64 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2289 EP 2292 DI 10.1029/96GL01109 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600023 ER PT J AU Crommelynck, D Fichot, A Domingo, V Lee, R AF Crommelynck, D Fichot, A Domingo, V Lee, R TI SOLCON solar constant observations from the ATLAS missions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The solar constant observations obtained by the SOLCON/ATLAS experiment during the three successive missions are presented based on the Space Absolute Radiometric Reference (SARR) defined during the ATLAS-2 mission. The objectives of SOLCON, namely to obtain accurate measurements of the solar constant and to compare them with the observations obtained from free flyers in the hope of establishing a baseline and strategy for monitoring the solar constant at climate scale, have been achieved successfully with the three ATLAS missions. The long range objective of insuring the solar constant data continuity will, however, require that an alternative approach than that of the ATLAS program be found to fly and retrieve SOLCON. C1 EUROPEAN SPACE AGCY,ESTEC,DEPT SPACE SCI,NL-2200 AG NOORDWIJK,NETHERLANDS. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP Crommelynck, D (reprint author), ROYAL METEOROL INST BELGIUM,DEPT AEROL,3 AVE CIRCULAIRE,B-1180 BRUSSELS,BELGIUM. NR 7 TC 18 Z9 18 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2293 EP 2295 DI 10.1029/96GL01878 PG 3 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600024 ER PT J AU Janz, SJ Hilsenrath, E Cebula, RP Kelly, TJ AF Janz, SJ Hilsenrath, E Cebula, RP Kelly, TJ TI Observations of the lunar geometric albedo during the ATLAS-3 mission SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CALIBRATION AB During the ATLAS-3 mission on the Space Shuttle Atlantis (STS-66) in November of 1994, a unique opportunity arose that enabled the solar-viewing instruments to observe ultraviolet radiation from the Moon. During these observations the Moon was at a phase angle of 51.8 degrees. Measurements by the Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument indicate lunar geometric albedo values, after correction to full moon, of 4.4%-8.3% in the wavelength range from 250 nm to 400 nm. These results are in good agreement with past measurements. C1 HUGHES STX CORP,GREENBELT,MD 20770. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Janz, SJ (reprint author), INT DEV & ENERGY ASSOCIATES INC,NASA,GSFC,CODE 916,BLDG 21,RM 257A,GREENBELT,MD 20771, USA. NR 19 TC 8 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2297 EP 2300 DI 10.1029/96GL01122 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600025 ER PT J AU Kriebel, DL Bevilacqua, RM Hilsenrath, E Gunson, M Hartmann, GK Abrams, M Daehler, M Pauls, TA Newchurch, M Aellig, CP Bories, MC AF Kriebel, DL Bevilacqua, RM Hilsenrath, E Gunson, M Hartmann, GK Abrams, M Daehler, M Pauls, TA Newchurch, M Aellig, CP Bories, MC TI A comparison of ozone measurements made by the ATMOS, MAS, and SSBUV instruments during ATLAS 1, 2, and 3 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Ozone profile measurements were made by three instruments, ATMOS, MAS, and SSBUV, using distinctly different observing techniques, as part of the ATLAS Space Shuttle missions in March 1992, April 1993, and November 1994. ATMOS makes solar-occultation observations of infrared spectra using a Fourier transform interferometer. MAS uses a limb-scanning antenna to measure emission spectra at millimeter wavelengths. SSBUV is a nadir-viewing instrument measuring the transmission of scattered solar ultraviolet radiation modified by ozone absorption. A sample of zonal-mean mixing ratio profiles indicates that these three ATLAS instruments generally agree to within 10%, although a few potential biases have been noted. There are significant differences in the character of the agreement between ATLAS 1 and ATLAS 2 which will require further study. C1 USN,RES LAB,DIV REMOTE SENSING,WASHINGTON,DC 20375. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. CALTECH,JET PROP LAB,PASADENA,CA 91109. MAX PLANCK INST AERON,LINDAU,GERMANY. UNIV ALABAMA,EARTH SYST SCI LAB,HUNTSVILLE,AL 35899. IDEA,BELTSVILLE,MD. RP Kriebel, DL (reprint author), COMPUTAT PHYS INC,2750 PROSPER AVE,SUITE 600,FAIRFAX,VA 22031, USA. NR 12 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2301 EP 2304 DI 10.1029/96GL01024 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600026 ER PT J AU Hilsenrath, E Newman, PA Cebula, RP DeCamp, PW Kelly, TJ Coy, L AF Hilsenrath, E Newman, PA Cebula, RP DeCamp, PW Kelly, TJ Coy, L TI Ozone change from 1992 to 1993 as observed from SSBUV on the ATLAS-1 and ATLAS-2 missions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID QUASI-BIENNIAL OSCILLATION; LOWER STRATOSPHERE; ATMOSPHERIC OZONE; UNITED-STATES; GLOBAL OZONE; DATA SET; CALIBRATION; INSTRUMENT; AEROSOL; FLIGHT AB The Shuttle SBUV (SSBUV) conducted its fourth and fifth flights in late March 1992 and early April 1993 along with the ATLAS-1 and ATLAS-2 Shuttle missions, respectively. The two successive SSBUV flights yielded ozone data nearly one year apart. An analysis of the meteorological conditions, namely temperature and winds, during the two flight periods indicate that the conditions in the stratosphere were very similar. The temperatures had significantly warmed from winter throughout most of the stratosphere and the circulation was approaching normal summertime conditions for both periods. SSBUV-4, flown in 1992, measured ozone from approximately 30S to 60N while SSBUV-5, flown in 1993, measured ozone from approximately 55S to 60N. Zonal average column ozone amounts were derived from the two flights and compared to determine if a systematic change in ozone could be detected despite the fact that only a few days from each year were sampled. The comparison indicates that in the latitude range 30N to 60N total ozone was lower in 1993 than in 1992 by about 12%. This change is larger than the observational errors and the expected interannual variations. This result verifies similar data taken from ground and satellites. C1 HUGHES STX CORP,GREENBELT,MD 20771. GEN SCI CORP,LAUREL,MD 20707. RP Hilsenrath, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 916,GREENBELT,MD 20771, USA. RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 26 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2305 EP 2308 DI 10.1029/96GL01120 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600027 ER PT J AU Hartmann, GK Bevilacqua, RM Schwartz, PR Kampfer, N Kunzi, KF Aellig, CP Berg, A Boogaerts, W Connor, BJ Croskey, CL Daehler, M Degenhardt, W Dicken, HD Goldizen, D Kriebel, D Langen, J Loidl, A Olivero, JJ Pauls, TA Puliafito, SE Richards, ML Rudin, C Tsou, JJ Waltman, WB Umlauft, G Zwick, R AF Hartmann, GK Bevilacqua, RM Schwartz, PR Kampfer, N Kunzi, KF Aellig, CP Berg, A Boogaerts, W Connor, BJ Croskey, CL Daehler, M Degenhardt, W Dicken, HD Goldizen, D Kriebel, D Langen, J Loidl, A Olivero, JJ Pauls, TA Puliafito, SE Richards, ML Rudin, C Tsou, JJ Waltman, WB Umlauft, G Zwick, R TI Measurements of O-3, H2O and ClO in the middle atmosphere using the millimeter-wave atmospheric sounder (MAS) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TRACERS AB The Millimeter-Wave Atmospheric Sounder (MAS) is a shuttle-based limb-sounding instrument designed for global spectroscopic studies of O-3, and constituents important in O-3 photochemistry, in the middle atmosphere. It is part of the NASA's Atmospheric Laboratory for Applications and Science (ATLAS) spacelab shuttle mission. This paper presents an overview of the instrument, operation, and data analysis. In addition, as an example of the results, we present zonal average retrievals for O-3, H2O, and ClO obtained in ATLAS 1. The MAS O-3 and H2O measurements are shown to agree well with simultaneous observations made with the UARS MLS instrument. C1 USN,RES LAB,REMOTE SENSING DIV,WASHINGTON,DC 20375. UNIV BERN,INST APPL PHYS,CH-3012 BERN,SWITZERLAND. UNIV BREMEN,INST REMOTE SENSING,BREMEN,GERMANY. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. PENN STATE UNIV,COMMUN & SPACE SCI LAB,UNIVERSITY PK,PA 16802. COMPUTAT PHYS INC,FAIRFAX,VA. EMBRY RIDDLE AERONAUT UNIV,DAYTONA BEACH,FL. UNIV MENDOZA,MENDOZA,ARGENTINA. RP Hartmann, GK (reprint author), MAX PLANCK INST AERON,POSTFACH 20,D-37189 KATLENBURG DUHM,GERMANY. OI Loidl, Alois/0000-0002-5579-0746 NR 11 TC 26 Z9 26 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2313 EP 2316 DI 10.1029/96GL01475 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600029 ER PT J AU Aellig, CP Kampfer, N Rudin, C Bevilacqua, RM Degenhardt, W Hartogh, P Jarchow, C Kunzi, K Olivero, JJ Croskey, C Waters, JW Michelsen, HA AF Aellig, CP Kampfer, N Rudin, C Bevilacqua, RM Degenhardt, W Hartogh, P Jarchow, C Kunzi, K Olivero, JJ Croskey, C Waters, JW Michelsen, HA TI Latitudinal distribution of upper stratospheric ClO as derived from space borne microwave spectroscopy SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OZONE; AIRBORNE; O-3; H2O; CIO AB Latitudinal distributions of upper stratospheric ClO measured by MAS during the three ATLAS missions are presented for northern hemisphere (NH) spring equinox in 1992, southern hemisphere (SH) early fall in 1993, and NH fall in 1994. The MAS ClO results are shown along with correlative MLS observations. The results of both instruments consistently show the same latitudinal features. The ClO maximum in the NH spring occurs at mid latitudes, whereas the latitudinal ClO maximum in both the NH and SH fall occurs at high latitudes. The volume mixing ratio maxima were significantly higher in the fall (0.7-0.8 ppbv) than in spring (0.5-0.6 ppbv). Qualitatively, these results are consistent with calculations of several 2-D models. C1 UNIV BERN, CH-3012 BERN, SWITZERLAND. GEORGE MASON UNIV, FAIRFAX, VA 22030 USA. MAX PLANCK INST AERON, LINDAU, GERMANY. EMBRY RIDDLE AERONAUT UNIV, DAYTONA BEACH, FL USA. PENN STATE UNIV, STATE COLL, PA USA. CALTECH, JET PROP LAB, PASADENA, CA USA. HARVARD UNIV, CAMBRIDGE, MA 02138 USA. RP USN, RES LAB, CODE 7227, WASHINGTON, DC 20375 USA. NR 14 TC 13 Z9 13 U1 0 U2 1 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 AUG 15 PY 1996 VL 23 IS 17 BP 2321 EP 2324 DI 10.1029/96GL01215 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600031 ER PT J AU Aellig, CP Bacmeister, J Bevilacqua, RM Daehler, M Kriebel, D Pauls, T Siskind, D Kampfer, N Langen, J Hartmann, G Berg, A Park, JH Russell, JM AF Aellig, CP Bacmeister, J Bevilacqua, RM Daehler, M Kriebel, D Pauls, T Siskind, D Kampfer, N Langen, J Hartmann, G Berg, A Park, JH Russell, JM TI Space-borne H2O observations in the Arctic stratosphere and mesosphere in the spring of 1992 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID POLAR VORTEX; WATER-VAPOR; ATMOSPHERE; TRANSPORT; DESCENT; MIDDLE; MODEL; AIR AB We report on stratospheric and mesospheric water vapor (H2O) observations obtained by the Millimeter wave Atmospheric Sounder (MAS) in the Arctic spring of 1992. In the lower stratosphere, the observations show enhanced H2O inside the vortex between 450 K and 625 K, in agreement with other H2O observations. In the upper stratosphere and lower mesosphere, at potential temperatures between 1850 K and 2200 K, we find regions of depressed H2O volume mixing ratio coincident with remnants of high potential vorticity. The depressed mesospheric H2O, as well as the enhanced lower stratospheric H2O, are consistent with wintertime descent. It also suggests effective containment of air up into the lower mesosphere. C1 GEORGE MASON UNIV,FAIRFAX,VA 22030. UNIV BERN,CH-3012 BERN,SWITZERLAND. COMPUTAT PHYS INC,FAIRFAX,VA. EUROPEAN SPACE AGCY,NOORDWIJK,NETHERLANDS. MAX PLANCK INST AERON,LINDAU,GERMANY. UNIV BREMEN,D-2800 BREMEN 33,GERMANY. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP Aellig, CP (reprint author), USN,RES LAB,CODE 7220,WASHINGTON,DC 20375, USA. NR 11 TC 15 Z9 15 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2325 EP 2328 DI 10.1029/96GL01571 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600032 ER PT J AU Gunson, MR Abbas, MM Abrams, MC Allen, M Brown, LR Brown, TL Chang, AY Goldman, A Irion, FW Lowes, LL Mahieu, E Manney, GL Michelsen, HA Newchurch, MJ Rinsland, CP Salawitch, RJ Stiller, GP Toon, GC Yung, YL Zander, R AF Gunson, MR Abbas, MM Abrams, MC Allen, M Brown, LR Brown, TL Chang, AY Goldman, A Irion, FW Lowes, LL Mahieu, E Manney, GL Michelsen, HA Newchurch, MJ Rinsland, CP Salawitch, RJ Stiller, GP Toon, GC Yung, YL Zander, R TI The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment: Deployment on the ATLAS Space Shuttle missions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LOWER STRATOSPHERE; UPPER TROPOSPHERE; CHLORINE; SPECTRA; N2O5 AB The ATMOS Fourier transform spectrometer was flown for a fourth time on the Space Shuttle as part of the ATLAS-3 instrument payload in November 1994. More than 190 sunrise and sunset occultation events provided measurements of more than 30 atmospheric trace gases at latitudes 3-49 degrees N and 65-72 degrees S, including observations both inside and outside the Antarctic polar vortex. The instrument configuration, data retrieval methodology, and mission background are described to place in context analyses of ATMOS data presented in this issue. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23665. CALTECH,PASADENA,CA 91125. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. UNIV LIEGE,INST ASTROPHYS,LIEGE,BELGIUM. HARVARD UNIV,CAMBRIDGE,MA 02138. UNIV ALABAMA,HUNTSVILLE,AL 35899. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. IMK,FORSCHUNGSZENTRUM KARLSRUHE,KARLSRUHE,GERMANY. RP Gunson, MR (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MAIL STOP 183-301,PASADENA,CA 91109, USA. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013; OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873; Mahieu, Emmanuel/0000-0002-5251-0286 NR 19 TC 159 Z9 160 U1 1 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2333 EP 2336 DI 10.1029/96GL01569 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600034 ER PT J AU Abrams, MC Chang, AY Gunson, MR Abbas, MM Goldman, A Irion, FW Michelsen, HA Newchurch, MJ Rinsland, CP Stiller, GP Zander, R AF Abrams, MC Chang, AY Gunson, MR Abbas, MM Goldman, A Irion, FW Michelsen, HA Newchurch, MJ Rinsland, CP Stiller, GP Zander, R TI On the assessment and uncertainty of atmospheric trace gas burden measurements with high resolution infrared solar occultation spectra from space by the ATMOS experiment SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument is a high resolution Fourier transform spectrometer that measures atmospheric composition from low Earth orbit with infrared solar occultation sounding in the limb geometry. Following an initial flight in 1985, ATMOS participated in the Atmospheric Laboratory for Applications and Science (ATLAS) 1, 2, and 3 Space Shuttle missions in 1992, 1993, and 1994 yielding a total of 440 occultation measurements over a nine year period. The suite of more than thirty atmospheric trace gases profiled includes CO2, O-3, N2O, CH4, H2O, NO, NO2, HNO3, HCl, HF, ClONO2, CCl3F, CCl2F2, CHF2Cl, and N2O5. The analysis method has been revised throughout the mission years culminating in the 'version 2' data set. The spectroscopic error analysis is described in the context of supporting the precision estimates reported with the profiles; in addition, systematic uncertainties assessed from the quality of the spectroscopic database are described and tabulated for comparisons with other experiments. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV DENVER,DENVER,CO 80208. HARVARD UNIV,CAMBRIDGE,MA 02138. UNIV ALABAMA,HUNTSVILLE,AL 35899. FORSCHUNGSZENTRUM KARLSRUHE,KARLSRUHE,GERMANY. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. RP Abrams, MC (reprint author), NASA,LANGLEY RES CTR,SAIC,MS-475,HAMPTON,VA 23681, USA. RI Stiller, Gabriele/A-7340-2013 OI Stiller, Gabriele/0000-0003-2883-6873 NR 6 TC 40 Z9 40 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2337 EP 2340 DI 10.1029/96GL01794 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600035 ER PT J AU Abrams, MC Manney, GL Gunson, MR Abbas, MM Chang, AY Goldman, A Irion, FW Michelsen, HA Newchurch, MJ Rinsland, CP Salawitch, RJ Stiller, GP Zander, R AF Abrams, MC Manney, GL Gunson, MR Abbas, MM Chang, AY Goldman, A Irion, FW Michelsen, HA Newchurch, MJ Rinsland, CP Salawitch, RJ Stiller, GP Zander, R TI ATMOS/ATLAS-3 observations of long-lived tracers and descent in the Antarctic vortex in November 1994 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC POLAR VORTEX; AIR AB Observations of the long-lived tracers N2O, CH4 and HF obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument in early November 1994 are used to estimate average descent rates during winter in the Antarctic polar vortex of 0.5 to 1.5 km/month in the lower stratosphere, and 2.5 to 3.5 km/month in the middle and upper stratosphere. Descent rates inferred from ATMOS tracer observations agree well with theoretical estimates obtained using radiative heating calculations. Air of mesospheric origin (N2O <5 ppbV) was observed at altitudes above about 25 km within the vortex. Strong horizontal gradients of tracer mixing ratios, the presence of mesospheric air in the vortex in early spring, and the variation with altitude of inferred descent rates indicate that the Antarctic vortex is highly isolated from midlatitudes throughout the winter from approximately 20 km to the stratopause. The 1994 Antarctic vortex remained well isolated between 20 and 30 km through at least mid-November. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV DENVER,DENVER,CO 80208. HARVARD UNIV,CAMBRIDGE,MA 02138. UNIV ALABAMA,HUNTSVILLE,AL 35899. FORSCHUNGSZENTURM KARLSRUHE,KARLSRUHE,GERMANY. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. RP Abrams, MC (reprint author), NASA,LANGLEY RES CTR,SAIC,MS-475,HAMPTON,VA 23681, USA. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013 OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873 NR 10 TC 39 Z9 39 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2341 EP 2344 DI 10.1029/96GL00705 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600036 ER PT J AU Abrams, MC Manney, GL Gunson, MR Abbas, MM Chang, AY Goldman, A Irion, FW Michelsen, HA Newchurch, MJ Rinsland, CP Salawitch, RJ Stiller, GP Zander, R AF Abrams, MC Manney, GL Gunson, MR Abbas, MM Chang, AY Goldman, A Irion, FW Michelsen, HA Newchurch, MJ Rinsland, CP Salawitch, RJ Stiller, GP Zander, R TI Trace gas transport in the Arctic vortex inferred from ATMOS ATLAS-2 observations during April 1993 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC POLAR VORTEX; PROFILE OBSERVATIONS; SUBSIDENCE; WINTER AB Measurements of the long-lived tracers CH4, N2O, and HF from the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during the Atmospheric Laboratory for Science and Applications-2 (ATLAS-2) Space Shuttle mission in April 1993 are used to infer average winter descent rates ranging from 0.8 km/month at 20 km to 3.2 km/month at 40 km in the Arctic polar vortex during the 1992-93 winter. Descent rates in the mid-stratosphere are similar to those deduced for the Antarctic vortex using ATMOS/ATLAS-3 measurements in November 1994, but the shorter time period of descent in the Arctic leads to smaller total distances of descent. Strong horizontal gradients observed along the vortex edge indicate that the Arctic vortex remains a significant barrier to transport at least until mid-April in the lower to middle stratosphere. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV DENVER,DENVER,CO 80208. HARVARD UNIV,CAMBRIDGE,MA 02138. UNIV ALABAMA,HUNTSVILLE,AL 35899. FORSCHUNGSZENTRUM KARLSRUHE,KARLSRUHE,GERMANY. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. RP Abrams, MC (reprint author), NASA,LANGLEY RES CTR,SAIC,MS-475,HAMPTON,VA 23681, USA. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013 OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873 NR 13 TC 34 Z9 34 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2345 EP 2348 DI 10.1029/96GL00704 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600037 ER PT J AU Rinsland, CP Mahieu, E Zander, R Gunson, MR Salawitch, RJ Chang, AY Goldman, A Abrams, MC Abbas, MM Newchurch, MJ Irion, FW AF Rinsland, CP Mahieu, E Zander, R Gunson, MR Salawitch, RJ Chang, AY Goldman, A Abrams, MC Abbas, MM Newchurch, MJ Irion, FW TI Trends of OCS, HCN, SF6, CHClF2, (HCFC-22) in the lower stratosphere from 1985 and 1994 atmospheric trace molecule spectroscopy experiment measurements near 30 degrees N latitude SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VERTICAL COLUMN ABUNDANCES; LONG-TERM TRENDS; SULFUR-HEXAFLUORIDE; EARTHS ATMOSPHERE; SOLAR SPECTRA; VARIABILITY; JUNGFRAUJOCH; LIFETIMES; INCREASE; MASS AB Volume mixing ratio (VMR) profiles of OCS, HCN, SF6, and CHClF2 (HCFC-22) have been measured near 30 degrees N latitude by the Atmospheric Trace Molecule Spectroscopy Fourier transform spectrometer during shuttle flights on 29 April-6 May 1985 and 3-2 November 1994. The change in the concentration of each molecule in the lower stratosphere has been derived for this 9 1/2-year period by comparing measurements between potential temperatures of 395 to 800 K (similar to 17 to 30 km altitude) relative to simultaneously measured values of the long-lived tracer N2O. Exponential rates of increase inferred for 1985-to-1994 from these comparisons are (0.1 +/- 0.4)% yr(-1) for OCS, (1.0 +/- 1.0)% yr(-1) for HCN, (8.0+/-0.7)% yr(-1) for SF6, and (8.0 +/- 1.0)% yr(-1) for CHClF2 (HCFC-22), 1 sigma. The lack of an appreciable trend for OCS suggests the background (i.e., nonvolcanic) source of stratospheric aerosol was the same during the two periods. These results are compared with trends reported in the literature. C1 UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. UNIV ALABAMA,HUNTSVILLE,AL 35899. CALTECH,DEPT CHEM ENGN,PASADENA,CA 91125. SCI APPLICAT INT CORP,HUNTSVILLE,AL 35889. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Rinsland, CP (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 401A,HAMPTON,VA 23681, USA. RI Salawitch, Ross/B-4605-2009 OI Salawitch, Ross/0000-0001-8597-5832 NR 24 TC 24 Z9 24 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2349 EP 2352 DI 10.1029/96GL01234 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600038 ER PT J AU Zander, R Solomon, S Mahieu, E Goldman, A Rinsland, CP Gunson, MR Abrams, MC Chang, AY Salawitch, RJ Michelsen, HA Newchurch, MJ Stiller, GP AF Zander, R Solomon, S Mahieu, E Goldman, A Rinsland, CP Gunson, MR Abrams, MC Chang, AY Salawitch, RJ Michelsen, HA Newchurch, MJ Stiller, GP TI Increase of stratospheric carbon tetrafluoride (CF4) based on ATMOS observations from space SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MOLECULE SPECTROSCOPY EXPERIMENT; C2F6; N2O AB Stratospheric volume mixing ratio profiles of carbon tetrafluoride, CF4, obtained with the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during the ATLAS (Atmospheric Laboratory for Applications and Science) -3 mission of 1994 are reported. Overall the profiles are nearly constant over the altitude range 20 to 50 km, indicative of the very long lifetime of CF4 in the atmosphere. In comparison to the stratospheric values of CF4 inferred from the ATMOS/Spacelab 3 mission of 1985, the 1994 concentrations are consistent with an exponential increase of (1.6 +/- 0.6)%/yr. This increase is discussed with regard to previous results and likely sources of CF4 at the ground. Further, it is shown that simultaneous measurements of N2O and CF4 provide a means of constraining the lower limit of the atmospheric lifetime of CF4 at least 2,300 years, two sigma. C1 NOAA,AERON LAB,BOULDER,CO 80303. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. UNIV ALABAMA,HUNTSVILLE,AL 35899. NASA,LANGLEY RES CTR,ASD,HAMPTON,VA 23681. IMK,FORSCHUNGSZENTRUM,KARLSRUHE,GERMANY. CALTECH,JET PROP LAB,PASADENA,CA. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23665. RP Zander, R (reprint author), UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013; OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873; Mahieu, Emmanuel/0000-0002-5251-0286 NR 26 TC 24 Z9 25 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2353 EP 2356 DI 10.1029/96GL00957 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600039 ER PT J AU Zander, R Mahieu, E Gunson, MR Abrams, MC Chang, AY Abbas, M Aellig, C Engel, A Goldman, A Irion, FW Kampfer, N Michelsen, HA Newchurch, MJ Rinsland, CP Salawitch, RJ Stiller, GP Toon, GC AF Zander, R Mahieu, E Gunson, MR Abrams, MC Chang, AY Abbas, M Aellig, C Engel, A Goldman, A Irion, FW Kampfer, N Michelsen, HA Newchurch, MJ Rinsland, CP Salawitch, RJ Stiller, GP Toon, GC TI The 1994 northern midlatitude budget of stratospheric chlorine derived from ATMOS/ATLAS-3 observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MOLECULE SPECTROSCOPY EXPERIMENT; SPACELAB-3 AB Volume mixing ratio (VMR) profiles of the chlorine-bearing gases HCl, ClONO2, CCl3F, CCl2F2, CHClF2, CCl4, and CH3Cl have been measured between 3 and 49 degrees northern- and 65 to 72 degrees southern latitudes with the Atmospheric Trace MOlecule Spectroscopy (ATMOS) instrument during the ATmospheric Laboratory for Applications and Science (ATLAS)-3 shuttle mission of 3 to 12 November 1994. A subset of these profiles obtained between 20 and 49 degrees N at sunset, combined with ClO profiles measured by the Millimeter-wave Atmospheric Sounder (MAS) also from aboard ATLAS-3, measurements by balloon for HOCl, CH3CCl3 and C2Cl3F3, and model calculations for COClF indicates that the mean burden of chlorine, Cl-TOT, was equal to (3.53 +/- 0.10) ppbv (parts per billion by volume), 1-sigma, throughout the stratosphere at the time of the ATLAS 3 mission. This is some 37% larger than the mean 2.58 ppbv value measured by ATMOS within the same latitude zone during the Spacelab 3 flight of 29 April to 6 May 1985, consitent with an exponential growth rate of the chlorine loading in the stratosphere equal to 3.3%/yr or a linear increase of 0.10 ppbv/yr over the Spring-1985 to Fall-1994 time period. These findings are in agreement with both the burden and increase of the main anthropogenic Cl-bearing source gases at the surface during the 1980s, confirming that the stratospheric chlorine loading is primarily of anthropogenic origin. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, ESSL, HUNTSVILLE, AL 35889 USA. USN, RES LAB, WASHINGTON, DC 20375 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. FORSCHUNGSZENTRUM JULICH, FORSCHUNGSZENTRUM, D-5170 JULICH, GERMANY. UNIV DENVER, DEPT PHYS, DENVER, CO 80208 USA. CALTECH, DEPT CHEM ENGN, PASADENA, CA 91125 USA. UNIV BERN, INST APPL PHYS, CH-3012 BERN, SWITZERLAND. HARVARD UNIV, DEPT EARTH & PLANETARY SCI, CAMBRIDGE, MA 02138 USA. UNIV ALABAMA, HUNTSVILLE, AL 35899 USA. IMK, FORSCHUNGSZENTRUM, KARLSRUHE, GERMANY. RP UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013; Engel, Andreas/E-3100-2014; OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873; Engel, Andreas/0000-0003-0557-3935; Mahieu, Emmanuel/0000-0002-5251-0286 NR 18 TC 60 Z9 60 U1 1 U2 5 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 AUG 15 PY 1996 VL 23 IS 17 BP 2357 EP 2360 DI 10.1029/96GL01792 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600040 ER PT J AU Michelsen, HA Salawitch, RJ Gunson, MR Aellig, C Kampfer, N Abbas, MM Abrams, MC Brown, TL Chang, AY Goldman, A Irion, FW Newchurch, MJ Rinsland, CP Stiller, GP Zander, R AF Michelsen, HA Salawitch, RJ Gunson, MR Aellig, C Kampfer, N Abbas, MM Abrams, MC Brown, TL Chang, AY Goldman, A Irion, FW Newchurch, MJ Rinsland, CP Stiller, GP Zander, R TI Stratospheric chlorine partitioning: Constraints from shuttle-borne measurements of [HCl], [ClNO3], and [ClO] SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BRANCHING RATIO; RATE CONSTANTS; OH; PHOTOLYSIS; KINETICS AB Measured stratospheric mixing ratios of HCl, ClNO3, and ClO from ATMOS and MAS are poorly reproduced by models using recommended kinetic parameters. This discrepancy is not resolved by new rates for the reactions Cl+CH4 and OH+HCl derived from weighted fits to laboratory measurements. A deficit in modeled [HCl] and corresponding overprediction of [ClNO3] and [ClO], which increases with altitude, suggests that production of HCl between 20 and 50 km is much faster than predicted from recommended rates. C1 CALTECH,JET PROP LAB,PASADENA,CA. USN,RES LAB,WASHINGTON,DC 20375. UNIV BERN,INST APPL PHYS,CH-3012 BERN,SWITZERLAND. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. UNIV ALABAMA,EARTH SYST SCI LAB,HUNTSVILLE,AL 35899. UNIV KARLSRUHE,FORSCHUNGSZENTRUM,KARLSRUHE,GERMANY. UNIV LIEGE,INST ASTROPHYS,COINTE OUGREE,BELGIUM. RP Michelsen, HA (reprint author), HARVARD UNIV,ARP,DIV APPL SCI,12 OXFORD ST,CAMBRIDGE,MA 02138, USA. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013 OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873 NR 17 TC 51 Z9 52 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2361 EP 2364 DI 10.1029/96GL00787 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600041 ER PT J AU Rinsland, CP Gunson, MR Salawitch, RJ Michelsen, HA Zander, R Newchurch, MJ Abbas, MM Abrams, MC Manney, GL Chang, AY Irion, FW Goldman, A Mahieu, E AF Rinsland, CP Gunson, MR Salawitch, RJ Michelsen, HA Zander, R Newchurch, MJ Abbas, MM Abrams, MC Manney, GL Chang, AY Irion, FW Goldman, A Mahieu, E TI ATMOS/ATLAS-3 measurements of stratospheric chlorine and reactive nitrogen partitioning inside and outside the November 1994 Antarctic vortex SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HCL AB Partitioning between HCl and ClONO2 and among the main components of the reactive nitrogen family (NO, NO2, HNO3, ClONO2, N2O5, and HO2NO2) has been studied inside and outside the Antarctic stratospheric vortex based on ATMOS profiles measured at sunrise during the 3-12 November 1994 ATLAS-3 Shuttle mission. Elevated mixing ratios of HCl in the lower stratosphere with a peak of similar to 2.9 ppbv (10(-9) parts per volume) were measured inside the vortex near 500 K potential temperature (similar to 19 km). Maximum ClONO2 mixing ratios of similar to 1.2, similar to 1.4, and similar to 0.9 ppbv near 700 K (similar to 25 km) were measured inside, at the edge, and outside the vortex, respectively. Model calculations reproduce the higher levels of HCl and NOx (NO + NO2) inside the lower stratospheric vortex both driven by photochemical processes initiated by low O-3. The high HCl at low O-3 results from chemical production of HCl via the reaction of enhanced Cl with CH4, limited production of ClONO2, and the descent of inorganic chlorine from higher altitudes. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. HARVARD UNIV,CAMBRIDGE,MA 02138. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. UNIV ALABAMA,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. SCI APPLICAT INT CORP,MCLEAN,VA 22102. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. RP Rinsland, CP (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 401A,HAMPTON,VA 23681, USA. RI Salawitch, Ross/B-4605-2009; OI Salawitch, Ross/0000-0001-8597-5832; Mahieu, Emmanuel/0000-0002-5251-0286 NR 9 TC 29 Z9 29 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2365 EP 2368 DI 10.1029/96GL01474 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600042 ER PT J AU Kondo, Y Schmidt, U Sugita, T Engel, A Koike, M Aimedieu, P Gunson, MR Rodriguez, J AF Kondo, Y Schmidt, U Sugita, T Engel, A Koike, M Aimedieu, P Gunson, MR Rodriguez, J TI NOy correlation with N2O and CH4 in the midlatitude stratosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WINTER POLAR STRATOSPHERES; AASE-II; DENITRIFICATION; NITROGEN; OZONE AB Total reactive nitrogen (NOy), nitrous oxide (N2O), methane (CH4), and ozone (O-3) were measured on board a balloon launched from Aire sur l'Adour (44 degrees N, 0 degrees W), France on October 12, 1994. Generally, NOy was highly anti-correlated with N2O and CH4 at altitudes between 15 and 32 km. The linear NOy - N2O and NOy - CH4 relationships obtained by the present observations are very similar to those obtained on board ER-2 and DC-8 aircraft previously at altitude below 20 km in the northern hemisphere. They also agree well with the data obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument at 41 degrees N in November 1994. Slight departures from linear correlations occurred around 29 km, where N2O and CH4 mixing ratios were larger than typical midlatitude values, suggesting horizontal transport of tropical airmasses to northern midlatitudes in a confined altitude region. C1 UNIV FRANKFURT, INST METEOROL & GEOPHYS, D-60054 FRANKFURT, GERMANY. FORSCHUNGSZENTRUM JULICH, FORSCHUNGSZENTRUM, INST STRATOSPHER CHEM, D-52425 JULICH, GERMANY. CNRS, SERV AERON, F-91370 VERRIERES LE BUISSON, FRANCE. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. ATMOSPHER & ENVIRONM RES INC, CAMBRIDGE, MA 02139 USA. RP NAGOYA UNIV, SOLAR TERR ENVIRONM LAB, TOYOKAWA, AICHI 442, JAPAN. RI Koike, Makoto/F-4366-2011; Kondo, Yutaka/D-1459-2012; Engel, Andreas/E-3100-2014; OI Engel, Andreas/0000-0003-0557-3935; Sugita, Takafumi/0000-0002-0508-7040 NR 15 TC 23 Z9 23 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 AUG 15 PY 1996 VL 23 IS 17 BP 2369 EP 2372 DI 10.1029/96GL00870 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600043 ER PT J AU Newchurch, MJ Allen, M Gunson, MR Salawitch, RJ Collins, GB Huston, KH Abbas, MM Abrams, MC Chang, AY Fahey, DW Gao, RS Irion, FW Loewenstein, M Manney, GL Michelsen, HA Podolske, JR Rinsland, CP Zander, R AF Newchurch, MJ Allen, M Gunson, MR Salawitch, RJ Collins, GB Huston, KH Abbas, MM Abrams, MC Chang, AY Fahey, DW Gao, RS Irion, FW Loewenstein, M Manney, GL Michelsen, HA Podolske, JR Rinsland, CP Zander, R TI Stratospheric NO and NO2 abundances from ATMOS solar-occultation measurements SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DIURNAL-VARIATION; NITRIC-OXIDE; NITROGEN; SPACELAB-3; TWILIGHT; CLO AB Using results from a time-dependent photochemical model to calculate the diurnal variation of NO and NO2, we have corrected Atmospheric Trace MOlecule Spectroscopy (ATMOS) solar-occultation retrievals of the NO and NO2 abundances at 90 degrees solar zenith angle. Neglecting to adjust for the rapid variation of these gases across the terminator results in potential errors in retrieved profiles of similar to 20% for NO2 and greater than 100% for NO at altitudes below 25 km. Sensitivity analysis indicates that knowledge of the local O-3 and temperature profiles, rather than zonal mean or climatological conditions of these quantities, is required to obtain reliable retrievals of NO and NO2 in the lower stratosphere. Extremely inaccurate O-3 or temperature values at 20 km can result in 50% errors in retrieved NO or NO2. Mixing ratios of NO in the mid-latitude, lower stratosphere measured by ATMOS during the November 1994 ATLAS-3 mission compare favorably with in situ ER-2 observations, providing strong corroboration of the reliability of the adjusted space-borne measurements. C1 CALTECH,JET PROP LAB,PASADENA,CA. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23665. NOAA,AERON LAB,BOULDER,CO 80303. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. HARVARD UNIV,CAMBRIDGE,MA 02138. UNIV LIEGE,LIEGE,BELGIUM. RP Newchurch, MJ (reprint author), UNIV ALABAMA,EARTH SYST SCI LAB,HUNTSVILLE,AL 35899, USA. RI Salawitch, Ross/B-4605-2009; Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Fahey, David/0000-0003-1720-0634 NR 18 TC 32 Z9 33 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2373 EP 2376 DI 10.1029/96GL01196 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600044 ER PT J AU Irion, FW Gunson, MR Rinsland, CP Yung, YL Abrams, MC Chang, AY Goldman, A AF Irion, FW Gunson, MR Rinsland, CP Yung, YL Abrams, MC Chang, AY Goldman, A TI Heavy ozone enrichments from ATMOS infrared solar spectra SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ABSORPTION-SPECTROSCOPY; STRATOSPHERIC OZONE; LINE POSITIONS; ISOTOPE; INTENSITIES; BANDS; NU-1 AB Vertical enrichment profiles of stratospheric (OOO)-O-16-O-16-O-18 and (OOO)-O-16-O-18-O-16 (hereafter referred to as O-668(3) and O-686(3) respectively) have been derived from space-based solar occultation spectra recorded at 0.01 cm(-1) resolution by the ATMOS (Atmospheric Trace MOlecule Spectroscopy) Fourier-transform infrared (FTIR) spectrometer. The observations, made during the Spacelab 3 and ATLAS-1, -2, and -3 shuttle missions, cover polar, mid-latitude and tropical regions between 26 to 2.6 mb inclusive (approximate to 25 to 41 km). Average enrichments, weighted by molecular O-48(3) density, of (15 +/- 6)% were found for O-668(3) and (10 +/- 7)% for O-686(3). Defining the mixing ratio of O-50(3) as the sum of those for O-668(3) and O-686(3), an enrichment of (13 +/- 5)% was found for O-50(3) (1 sigma standard deviation). No latitudinal or vertical gradients were found outside this standard deviation. From a series of ground-based measurements by the ATMOS instrument at Table Mountain, California (34.4 degrees N), an average total column O-668(3) enrichment of (17 +/- 4)% (1 sigma standard deviation) was determined, with no significant seasonal variation discernable. Possible biases in the spectral intensities that affect the determination of absolute enrichments are discussed. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23681. UNIV DENVER,DEPT PHYS,DENVER,CO 80210. RP Irion, FW (reprint author), CALTECH,DEPT PLANETARY SCI,PASADENA,CA 91125, USA. NR 28 TC 44 Z9 44 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2377 EP 2380 DI 10.1029/96GL01695 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600045 ER PT J AU Irion, FW Moyer, EJ Gunson, MR Rinsland, CP Yung, YL Michelsen, HA Salawitch, RJ Chang, AY Newchurch, MJ Abbas, MM Abrams, MC Zanders, R AF Irion, FW Moyer, EJ Gunson, MR Rinsland, CP Yung, YL Michelsen, HA Salawitch, RJ Chang, AY Newchurch, MJ Abbas, MM Abrams, MC Zanders, R TI Stratospheric observations of CH3D and HDO from ATMOS infrared solar spectra: Enrichments of deuterium in methane and implications for HD SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID OH AB Stratospheric mixing ratios of CH3D from 100 mb to 17 mb (approximate to 15 to 28 km) and HDO from 100 mb to 10 mb (approximate to 15 to 32 km) have been inferred from high resolution solar occultation infrared spectra from the Atmospheric Trace MOlecule Spectroscopy (ATMOS) Fourier-transform interferometer. The spectra, taken on board the Space Shuttle during the Spacelab 3 and ATLAS-1, -2, and -3 missions, extend in latitude from 70 degrees S to 65 degrees N. We find CH3D entering the stratosphere at an average mixing ratio of (9.9 +/- 0.8) x 10(-10) with a D/H ratio in methane (7.1 +/- 7.4)% less than that in Standard Mean Ocean Water (SMOW) (1 sigma combined precision and systematic error). In the mid to lower stratosphere, the average lifetime of CH3D is found to be (1.19 +/- 0.02) times that of CH4, resulting in an increasing D/H ratio in methane as air ''ages'' and the methane mixing ratio decreases. We find an average of (1.0 +/- 0.1) molecules of stratospheric HDO are produced for each CH3D destroyed (1 sigma combined precision and systematic error), indicating that the rate of HDO production is approximately equal to the rate of CH3D destruction. Assuming negligible amounts of deuterium in species other than HDO, CH3D and HD, this limits the possible change in the stratospheric HD mixing ratio below about 10 mb to be +/- 0.1 molecules HD created per molecule CH3D destroyed. C1 CALTECH,JET PROPULS LAB,PASADENA,CA 91109. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. HARVARD UNIV,CAMBRIDGE,MA 02138. UNIV ALABAMA,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23681. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. RP Irion, FW (reprint author), CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125, USA. RI Salawitch, Ross/B-4605-2009 OI Salawitch, Ross/0000-0001-8597-5832 NR 15 TC 54 Z9 54 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2381 EP 2384 DI 10.1029/96GL01402 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600046 ER PT J AU Moyer, EJ Irion, FW Yung, YL Gunson, MR AF Moyer, EJ Irion, FW Yung, YL Gunson, MR TI ATMOS stratospheric deuterated water and implications for troposphere-stratosphere transport SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SPECTRA; SCALE; VAPOR AB Measurements of the isotopic composition of stratospheric water by the ATMOS instrument are used to infer the convective history of stratospheric air. The average water vapor entering the stratosphere is found to be highly depleted of deuterium, with delta D-w of -670 +/- 80 (67% deuterium loss). Model calculations predict, however, that under conditions of thermodynamic equilibrium, dehydration to stratospheric mixing ratios should produce stronger depletion to delta D-w of -800 to -900 (80-90% deuterium loss). Deuterium enrichment of water vapor in ascending parcels can occur only in conditions of rapid convection; enrichments persisting into the stratosphere require that those conditions continue to near-tropopause altitudes. We conclude that either the predominant source of water vapor to the uppermost troposphere is enriched convective water, most likely evaporated cloud ice, or troposphere-stratosphere transport occurs closely associated with tropical deep convection. C1 CALTECH,DEPT CHEM & CHEM ENGN,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Moyer, EJ (reprint author), CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125, USA. NR 21 TC 107 Z9 107 U1 0 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2385 EP 2388 DI 10.1029/96GL01489 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600047 ER PT J AU Chang, AY Salawitch, RJ Michelsen, HA Gunson, MR Abrams, MC Zander, R Rinsland, CP Loewenstein, M Podolske, JR Proffitt, MH Margitan, JJ Fahey, DW Gao, RS Kelly, KK Elkins, JW Webster, CR May, RD Chan, KR Abbas, MM Goldman, A Irion, FW Manney, GL Newchurch, MJ Stiller, GP AF Chang, AY Salawitch, RJ Michelsen, HA Gunson, MR Abrams, MC Zander, R Rinsland, CP Loewenstein, M Podolske, JR Proffitt, MH Margitan, JJ Fahey, DW Gao, RS Kelly, KK Elkins, JW Webster, CR May, RD Chan, KR Abbas, MM Goldman, A Irion, FW Manney, GL Newchurch, MJ Stiller, GP TI A comparison of measurements from ATMOS and instruments aboard the ER-2 aircraft: Tracers of atmospheric transport SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ANTARCTIC OZONE EXPERIMENT; WATER AB We compare volume mixing ratio profiles of N2O, O-3, NOy, H2O, CH4, and CO in the mid-latitude lower stratosphere measured by the ATMOS Fourier transform spectrometer on the ATLAS-3 Space Shuttle Mission with in situ measurements acquired from the NASA ER-2 aircraft during Nov 1994. ATMOS and ER-2 observations of [N2O] show good agreement, as do measured correlations of [O-3], [NOy], [H2O], and [CH4] with [N2O]. Thus a consistent measure of the hydrogen (H2O, CH4) content of the lower stratosphere is provided by the two platforms. The similarity of [NOy] determined by detection of individual species by ATMOS and the total [NOy] measurement on the ER-2 provides strong corroboration for the accuracy of both techniques. A 25% discrepancy in lower stratospheric [CO] observed by ATMOS and the ER-2 remains unexplained. Otherwise, the agreement for measurements of long-lived tracers demonstrates the ability to combine ATMOS data with in situ observations for quantifying atmospheric transport. C1 HARVARD UNIV,CAMBRIDGE,MA 02138. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23665. UNIV LIEGE,INST ASTROPHYS,LIEGE,BELGIUM. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NOAA,AERON LAB,BOULDER,CO 80303. UNIV COLORADO,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. UNIV ALABAMA,HUNTSVILLE,AL 35899. IMK,FORSCHUNGSZENTRUM,KARLSRUHE,GERMANY. RP Chang, AY (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS,PASADENA,CA 91109, USA. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013; Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873; Fahey, David/0000-0003-1720-0634 NR 8 TC 35 Z9 35 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2389 EP 2392 DI 10.1029/96GL01677 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600048 ER PT J AU Chang, AY Salawitch, RJ Michelsen, HA Gunson, MR Abrams, MC Zander, R Rinsland, CP Elkins, JW Dutton, GS Volk, CM Webster, CR May, RD Fahey, DW Gao, RS Loewenstein, M Podolske, JR Stimpfle, RM Kohn, DW Proffitt, MH Margitan, JJ Chan, KR Abbas, MM Goldman, A Irion, FW Manney, GL Newchurch, MJ Stiller, GP AF Chang, AY Salawitch, RJ Michelsen, HA Gunson, MR Abrams, MC Zander, R Rinsland, CP Elkins, JW Dutton, GS Volk, CM Webster, CR May, RD Fahey, DW Gao, RS Loewenstein, M Podolske, JR Stimpfle, RM Kohn, DW Proffitt, MH Margitan, JJ Chan, KR Abbas, MM Goldman, A Irion, FW Manney, GL Newchurch, MJ Stiller, GP TI A comparison of measurements from ATMOS and instruments aboard the ER-2 aircraft: Halogenated gases SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LOWER STRATOSPHERE; REACTIVE NITROGEN; CHLORINE AB We compare volume mixing ratio profiles of N2O, CFC-11, CFC-12, CCl4, SF6, and HCl in the mid-latitude lower stratosphere measured by the ATMOS Fourier transform spectrometer on the ATLAS-3 Space Shuttle Mission with in situ measurements acquired from the NASA ER-2 aircraft during Nov 1994. Good agreement is found between ATMOS and in situ correlations of [CFC-II], [CFC-12], and [SF6] with [N2O]. ATMOS measurements of [CCl4] are 15% high compared to ER-2 data, but agree within the systematic uncertainties. ATMOS observations of [HCl] vs [N2O] are within similar to 10% of ER-2 data for [HCl] > 1 ppbv, but exceed in situ measurements by larger fractional amounts for smaller [HCl]. ATMOS measurements of [ClONO2] agree well with values inferred from in situ observations of [ClO], [NO], and [O-3]. The sum of [HCl] and [ClONO2] observed by ATMOS, supplemented by a minor contribution from [ClO] estimated with a photochemical model, is consistent with the levels of inorganic chlorine inferred from in situ measurements of chlorine source gases. C1 HARVARD UNIV,CAMBRIDGE,MA 02138. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23665. UNIV LIEGE,INST ASTROPHYS,LIEGE,BELGIUM. NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303. UNIV COLORADO,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. NOAA,AERON LAB,BOULDER,CO 80303. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. UNIV ALABAMA,HUNTSVILLE,AL 35899. IMK,FORSCHUNGSZENTRUM,KARLSRUHE,GERMANY. RP Chang, AY (reprint author), CALTECH,JET PROPULS LAB,4800 OAK GROVE DR,MS,PASADENA,CA 91109, USA. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013; Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873; Fahey, David/0000-0003-1720-0634 NR 13 TC 26 Z9 26 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2393 EP 2396 DI 10.1029/96GL01678 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600049 ER PT J AU Rinsland, CP Gunson, MR Salawitch, RJ Newchurch, MJ Zander, R Abbas, MM Abrams, MC Manney, GL Michelsen, HA Chang, AY Goldman, A AF Rinsland, CP Gunson, MR Salawitch, RJ Newchurch, MJ Zander, R Abbas, MM Abrams, MC Manney, GL Michelsen, HA Chang, AY Goldman, A TI ATMOS measurements of H2O+2CH(4) and total reactive nitrogen in the November 1994 Antarctic stratosphere: Dehydration and denitrification in the vortex SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WINTER POLAR STRATOSPHERES; WATER-VAPOR AB Simultaneous stratospheric volume mixing ratios (VMRs) measured inside and outside the Antarctic vortex by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument in November 1994 reveal previously unobserved features in the distributions of total reactive nitrogen (NOy) and total hydrogen (H2O+2CH(4)). Maximum removal of NOy due to sedimentation of polar stratospheric clouds (PSCs) inside the vortex occurred at a potential temperature (Theta) of 500-525 K (similar to 20 km), where values were 5 times smaller than measurements outside. Maximum loss of H2O+2CH(4) due to PSCs occurred in the vortex at 425-450 K, VMRs inside the vortex were similar to 70% of corresponding values out side. The Antarctic and April 1993 Arctic measurements by ATMOS show no significant differences in H2O+2CH(4) VMRs outside the vortices in the two hemispheres. Elevated NOy VMRs were measured inside the vortex near 700 K. Recent model calculations indicate that this feature results from downward transport of elevated NOy produced in the thermosphere and mesosphere. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV ALABAMA,HUNTSVILLE,AL 35899. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. NMSFC,SSL,HUNTSVILLE,AL 35889. HARVARD UNIV,DIV APPL SCI,CAMBRIDGE,MA 02138. HARVARD UNIV,DEPT EARTH & PLANETARY SCI,CAMBRIDGE,MA 02138. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. SYST & APPL SCI CORP,HAMPTON,VA. RP Rinsland, CP (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 401A,HAMPTON,VA 23681, USA. RI Salawitch, Ross/B-4605-2009 OI Salawitch, Ross/0000-0001-8597-5832 NR 17 TC 38 Z9 38 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2397 EP 2400 DI 10.1029/96GL00048 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600050 ER PT J AU Abbas, MM Michelsen, HA Gunson, MR Abrams, MC Newchurch, MJ Salawitch, RJ Chang, AY Goldman, A Irion, FW Manney, GL Moyer, EJ Nagaraju, R Rinsland, CP Stiller, GP Zander, R AF Abbas, MM Michelsen, HA Gunson, MR Abrams, MC Newchurch, MJ Salawitch, RJ Chang, AY Goldman, A Irion, FW Manney, GL Moyer, EJ Nagaraju, R Rinsland, CP Stiller, GP Zander, R TI Seasonal variations of water vapor in the lower stratosphere inferred from ATMOS/ATLAS-3 measurements of H2O and CH4 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BUDGET AB Stratospheric measurements of H2O and CH4 by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer on the ATLAS-3 shuttle flight in November 1994 have been examined to investigate the altitude and geographic variability of H2O and the quantity H = (H2O + 2CH(4)) in the tropics and at mid-latitudes (8 to 49 degrees N) in the northern hemisphere. The measurements indicate an average value of 7.24 +/- 0.44 ppmv for H between altitudes of about 18 to 35 km, corresponding to an annual average water vapor mixing ratio of 3.85 +/- 0.29 ppmv entering the stratosphere. The H2O vertical distribution in the tropics exhibits a wave-like structure in the 16- to 25-km altitude range, suggestive of seasonal variations in the water vapor transported from the troposphere to the stratosphere. The hygropause appears to be nearly coincident with the tropopause at the time of observations. This is consistent with the phase of the seasonal cycle of H2O in the lower stratosphere, since the ATMOS observations were made in November when the H2O content of air injected into the stratosphere from the troposphere is decreasing from its seasonal peak in July-August. C1 HARVARD UNIV,CAMBRIDGE,MA 02138. CALTECH,JET PROPULS LAB,PASADENA,CA 91125. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23665. UNIV ALABAMA,HUNTSVILLE,AL 35899. UNIV DENVER,DENVER,CO 80208. UNIV KARLSRUHE,FORSCHUNGSZENTRUM,KARLSRUHE,GERMANY. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. RP Abbas, MM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,MAIL CODE ES41,HUNTSVILLE,AL 35812, USA. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013 OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873 NR 20 TC 36 Z9 37 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2401 EP 2404 DI 10.1029/96GL01321 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600051 ER PT J AU Abbas, MM Gunson, MR Newchurch, MJ Michelsen, HA Salawitch, RJ Allen, M Abrams, MC Chang, AY Goldman, A Irion, FW Moyer, EJ Nagaraju, R Rinsland, CP Stiller, GP Zander, R AF Abbas, MM Gunson, MR Newchurch, MJ Michelsen, HA Salawitch, RJ Allen, M Abrams, MC Chang, AY Goldman, A Irion, FW Moyer, EJ Nagaraju, R Rinsland, CP Stiller, GP Zander, R TI The hydrogen budget of the stratosphere inferred from ATMOS measurements of H2O and CH4 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LATITUDE AB The total hydrogen budget of the stratosphere and lower mesosphere has been examined using vertical mixing ratio profiles of H2O and CH4 measured by the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment from four space shuttle missions. The oxidation of CH4 and H-2 is investigated by evaluating the quantity H (= H2O + 2 CH4) entering the stratosphere, and examining its conservation with altitude in the upper atmosphere. Data from all four ATMOS missions indicate H to be nearly conserved in the lower stratosphere and to exhibit a broad maximum in the 35- to 65-km range. The observations provide evidence of a secondary source of H2O from H-2 oxidation at altitudes from 35 to 55 km, and net production of H-2 at altitudes above similar to 55 km. ATMOS measurements of H2O and CH4 permit the first evaluation of a sickle-shaped vertical profile of H-2 that is qualitatively consistent with profiles calculated using two-dimensional models. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. UNIV ALABAMA,HUNTSVILLE,AL 35899. HARVARD UNIV,CAMBRIDGE,MA 02138. NASA,LANGLEY RES CTR,SAIC,HAMPTON,VA 23665. UNIV DENVER,DENVER,CO 80208. UNIV KARLSRUHE,FORSCHUNGSZENTRUM,KARLSRUHE,GERMANY. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. RP Abbas, MM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,MAIL CODE ES41,HUNTSVILLE,AL 35812, USA. RI Salawitch, Ross/B-4605-2009; Stiller, Gabriele/A-7340-2013 OI Salawitch, Ross/0000-0001-8597-5832; Stiller, Gabriele/0000-0003-2883-6873 NR 11 TC 27 Z9 27 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2405 EP 2408 DI 10.1029/96GL01320 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600052 ER PT J AU Manney, GL Swinbank, R ONeill, A AF Manney, GL Swinbank, R ONeill, A TI Stratospheric meteorological conditions for the 3-12 Nov 1994 ATMOS/ATLAS-3 measurements SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID POLAR VORTEX AB During the ATLAS-3 mission (3-12 Nov 1994), United Kingdom Meteorological Office fields show that the SH vortex was still strong below about 700 K (similar to 16 hPa), with coherent vortex fragments apparent up to about 1300 K (similar to 3 hPa). The SH vortex was shifted off the pole toward 270 degrees E throughout ATLAS-3, although its shape varied from day to day. SH temperatures were increasing during ATLAS-3; temperatures below 188 K were last seen 35-45 days before the mission, but were below 195 K as late as 2 Nov 1994. The NH polar vortex had developed at levels above about 550 K (similar to 35 hPa). Simulated high-resolution potential vorticity (PV) fields clearly show low latitude air being drawn up around the polar vortices in both hemispheres. These fields indicate that meteorological analyses underestimate the amount of atmospheric variability, including the strength of local PV gradients, and small-scale structure Structure such as that in the simulated fields can result in apparent discrepancies between tracer measurements and PV fields. C1 METEOROL OFF,CR DIV,BRACKNELL RG12 2SZ,BERKS,ENGLAND. UNIV READING,CTR GLOBAL ATMOSPHER MODELLING,READING RG6 2AU,BERKS,ENGLAND. RP Manney, GL (reprint author), CALTECH,JET PROP LAB,M-S 183-701,PASADENA,CA 91109, USA. NR 7 TC 27 Z9 27 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 15 PY 1996 VL 23 IS 17 BP 2409 EP 2412 DI 10.1029/96GL00774 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VD376 UT WOS:A1996VD37600053 ER PT J AU Jaffe, RL Smith, GD AF Jaffe, RL Smith, GD TI A quantum chemistry study of benzene dimer SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CLUSTERS AB We have performed a detailed quantum chemistry study of the gas-phase benzene dimer. Large atomic orbital basis sets with multiple polarization functions were used. The effects of basis set size, electron correlation, and basis set superposition error were investigated for the low-energy planar sandwich (D-6h and C-6v), parallel displaced (C-2h), and T-shaped (C-2v) dimer structures. Our studies indicate that the C-2h-symmetry parallel displaced geometry is the lowest-energy structure for the benzene dimer. The T-shaped structure was found to be a low-energy saddle point for interconversion between parallel displaced structures, while the planar sandwich structure was found to be a saddle point on a higher-energy interconversion path between parallel displaced structures. Detailed analysis of the low-energy (T-shaped saddle point) path revealed the presence of a shallow minimum corresponding to a tilt angle between phenyl ring planes of about 45 degrees. Much of the behavior of the benzene dimer observed through molecular jet spectroscopy can be explained by considering a population of the low-energy parallel displaced structure and structures along the low-energy interconversion path, including the tilt- and T-shaped structures. (C) 1996 American Institute of Physics. C1 UNIV MISSOURI, DEPT CHEM ENGN, COLUMBIA, MO 65211 USA. RP Jaffe, RL (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 23 TC 259 Z9 262 U1 0 U2 7 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD AUG 15 PY 1996 VL 105 IS 7 BP 2780 EP 2788 DI 10.1063/1.472140 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA VB452 UT WOS:A1996VB45200027 ER PT J AU Wadhams, P Comiso, JC Prussen, E Wells, S Brandon, M Aldworth, E Viehoff, T Allegrino, R Crane, DR AF Wadhams, P Comiso, JC Prussen, E Wells, S Brandon, M Aldworth, E Viehoff, T Allegrino, R Crane, DR TI The development of the Odden ice tongue in the Greenland Sea during winter 1993 from remote sensing and field observations SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID EDGE BANDS; MICROWAVE; OCEAN; HEAT AB The Odden ice tongue in the central Greenland Sea, believed to be associated with midgyre convection, developed prominently during the: winter of 1993 (January-April). During this period it was studied by a succession of cruises which formed part of the European Subpolar Ocean Programme and which included direct sampling and measurement of the frazil and pancake ice which constituted the material of the ice tongue as well as studies of the ocean structure. Passive microwave imagery was used to determine the evolution of Odden through the winter and, when combined with ERS 1 synthetic aperture radar studies and the field data, yielded estimates of ice extent and thickness through the winter. From these studies it was possible to estimate the salt flux into the ocean originating from brine release from sea ice during the growth phases of Odden. C1 NASA,GODDARD SPACE FLIGHT CTR,LAB HYDROSPHER PROC,GREENBELT,MD 20771. ALFRED WEGENER INST POLAR & MARINE RES,D-2850 BREMERHAVEN,GERMANY. HUGHES STX,LANHAM,MD. RP Wadhams, P (reprint author), UNIV CAMBRIDGE,SCOTT POLAR RES INST,CAMBRIDGE CB2 1ER,ENGLAND. RI Allegrino, Rico/E-7939-2011; Brandon, Mark/A-5804-2010 OI Allegrino, Rico/0000-0002-3468-5445; Brandon, Mark/0000-0002-7779-0958 NR 30 TC 39 Z9 39 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD AUG 15 PY 1996 VL 101 IS C8 BP 18213 EP 18235 DI 10.1029/96JC01440 PG 23 WC Oceanography SC Oceanography GA VC707 UT WOS:A1996VC70700013 ER PT J AU Comiso, JC Gordon, AL AF Comiso, JC Gordon, AL TI Cosmonaut polynya in the Southern Ocean: Structure and variability SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID THIN SEA-ICE; WEDDELL SEA; MIXED LAYER; MICROWAVE; SIMULATION; MODEL; GYRE AB Along the far eastern margin of the Weddell Gyre is a persistent feature in the middle of the ice pack which we previously reported and called the Cosmonaut polynya. A study of polynya occurrences from 1973 to 1993 reveals that since 1986 the polynya has become more active with an average size of about 7.2 x 10(4) km(2) and an average location at 52 degrees E and 65 degrees S. Satellite observations indicate that the polynya has recurred several times during winter in recent years with intervals ranging from a few days to a few weeks. The centroid of the polynya varies only slightly with each formation during the year and from one year to another, suggesting a controlling influence of the ocean and bottom topography that may be initially induced by wind. The daily time series indicates two primary modes of formation: one that is initiated in the early winter during a storm at a site usually preceded by an embayment of the ice edge and another that occurs during midwinter often preceded by a coastal polynya event adjacent to Cape Ann. The Cosmonaut polynya region is characterized in this study by compression of the westward flowing coastal current and the eastward flowing southern edge of the Antarctic Circumpolar Current. Following the principle of conservation of potential vorticity, vertical stretching of the water column would ensue, enhancing upwelling. Such a process accelerates the injection of relatively warm salty deep water into the surface layer, inhibiting sea ice growth and causing the polynya formation. This theory appears to explain the general behavior of the polynya in terms of frequency, duration, size, and location. C1 COLUMBIA UNIV, LAMONT DOHERTY EARTH OBSERV, PALISADES, NY 10964 USA. RP Comiso, JC (reprint author), NASA, GODDARD SPACE FLIGHT CTR, MAIL CODE 971, GREENBELT, MD 20771 USA. RI Gordon, Arnold/H-1049-2011 OI Gordon, Arnold/0000-0001-6480-6095 NR 44 TC 36 Z9 36 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 AUG 15 PY 1996 VL 101 IS C8 BP 18297 EP 18313 DI 10.1029/96JC01500 PG 17 WC Oceanography SC Oceanography GA VC707 UT WOS:A1996VC70700017 ER PT J AU Thorn, RP Stief, LJ Kuo, SC Klemm, RB AF Thorn, RP Stief, LJ Kuo, SC Klemm, RB TI Ionization energy of Cl2O and ClO, appearance energy of ClO+ (Cl2O), and heat of formation of Cl2O SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID PHOTOIONIZATION SPECTRUM; EQUILIBRIUM-CONSTANT; HALOGENS; OZONE AB The photoionization efficiency (PIE) spectrum of Cl2O was measured over the wavelength range lambda = 98-117 nm by using a discharge flow-photoionization mass spectrometer apparatus coupled to a synchrotron radiation source. A value of 10.90(9) +/- 0.01(6) eV was obtained for the adiabatic ionization energy (IE) of Cl2O from analysis of the photoionization thresholds. The ClO radical was produced via the reaction F + Cl2O --> FCl + ClO and the PIE spectrum of ClO was measured over the wavelength range lambda = 105-117 nm. Analysis of the photoionization threshold yields a value of IE of ClO(X(2) Pi(3/2)) = 10.88(5) +/- 0.01(6) eV. The appearance energy (AE) of ClO+ (from the dissociative ionization of Cl2O) was determined from the PIE spectrum of ClO+ over the wavelength range lambda = 98-104 nm. Combining the AE(298) value, 12.29(6) +/- 0.03(2) eV, with known thermodynamic quantities yields a value for Delta(f)H(298)(degrees)(Cl2O) = 77.2 +/- 3.4 kJ mol(-1). From the value for Delta(f)H(298)(degrees)(Cl2O) and the equilibrium constant for the reaction Cl2O + H2O <----> 2HOCl, a value for Delta(f)H(298)(degrees)(HOCl) = -76.8 +/- 3.5 kJ mol(-1) is obtained. These results for IE(Cl2O), IE(ClO), AE(298)(ClO+, Cl2O), Delta(f)H(298)(degrees)(Cl2O), and Delta(f)H(298)(degrees)(HOCl) are compared with previous estimates or measurements. C1 BROOKHAVEN NATL LAB,DEPT APPL SCI,UPTON,NY 11973. RP Thorn, RP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 690,GREENBELT,MD 20771, USA. NR 52 TC 35 Z9 36 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD AUG 15 PY 1996 VL 100 IS 33 BP 14178 EP 14183 DI 10.1021/jp961262j PG 6 WC Chemistry, Physical SC Chemistry GA VC550 UT WOS:A1996VC55000042 ER PT J AU Rezaeepazhand, J Simitses, GJ Starnes, JH AF Rezaeepazhand, J Simitses, GJ Starnes, JH TI Design of scaled down models for predicting shell vibration response SO JOURNAL OF SOUND AND VIBRATION LA English DT Article AB The importance of employing scaled down models in designing advanced composite structures has been gaining momentum in recent years. This study investigates problems associated with the design of scaled down models for vibration response. Such study is important since it provides the necessary scaling laws, and the factors which affect the accuracy of the scale models. The employment of similitude theory to establish similarity among structural systems can save considerable expense and time, provided that the proper scaling laws are found and validated. In this study a number of parametric studies are performed. The limitations and acceptable intervals of all parameters and corresponding scale factors are investigated. Particular emphasis is placed on the case of free vibration of cross-ply cylindrical shells. Both complete and partial similarity are discussed. This analytical study indicates that distorted models with a different number of layers and geometries than those of the prototype can predict the behaviour of the prototype with good accuracy. (C) 1996 Academic Press Limited C1 NASA,AIRCRAFT STRUCT BRANCH,LANGLEY RES CTR,HAMPTON,VA 23665. RP Rezaeepazhand, J (reprint author), UNIV CINCINNATI,DEPT AEROSP ENGN & ENGN MECH,CINCINNATI,OH 45221, USA. OI Rezaeepazhand, Jalil/0000-0003-3653-1623 NR 9 TC 38 Z9 41 U1 1 U2 8 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD AUG 15 PY 1996 VL 195 IS 2 BP 301 EP 311 DI 10.1006/jsvi.1996.0423 PG 11 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA VC562 UT WOS:A1996VC56200009 ER PT J AU Farassat, F Myers, MK AF Farassat, F Myers, MK TI A simple application of nonstandard analysis to forced vibration of a spring-mass system SO JOURNAL OF SOUND AND VIBRATION LA English DT Letter C1 GEORGE WASHINGTON UNIV,JIAFS,HAMPTON,VA. RP Farassat, F (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 7 TC 2 Z9 2 U1 0 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD AUG 15 PY 1996 VL 195 IS 2 BP 340 EP 345 DI 10.1006/jsvi.1996.0427 PG 6 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA VC562 UT WOS:A1996VC56200014 ER PT J AU Barker, HW Wielicki, BA Parker, L AF Barker, HW Wielicki, BA Parker, L TI A parameterization for computing grid-averaged solar fluxes for inhomogeneous marine boundary layer clouds .2. Validation using satellite data SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID RADIATIVE-TRANSFER; INDEPENDENT PIXEL; FIELDS; APPROXIMATIONS; ALBEDO AB The independent pixel approximation (IPA) is one of the simplest methods of computing solar radiative fluxes for inhomogeneous clouds. It claims that if p(tau) is a normalized probability density function for cloud optical depth tau and R(pp)(tau) is plane-parallel, homogeneous (PPH) albedo, mean cloud albedo can be approximated by integrating p(tau)R(pp)(tau) over all tau. The purpose of this study is to assess the ability of the gamma distribution function to represent p(tau) for marine boundary layer clouds and to examine the accuracy of the ensuing gamma IPA albedos. In a separate study, pixel values of tau were inferred from high spatial resolution Landsat imagery of marine boundary layer clouds. The present study utilizes 45 images, each measuring (58 km)(2). For each image, a density function p(obs)(tau) is estimated, and, using the mean <(tau)over bar> and variance of tau, a corresponding truncated gamma distribution function p(gamma)(tau) is defined. For a diverse range of clouds, p(gamma)(tau) usually approximate p(obs)(tau) well. The best results are for overcast stratocumulus and small, broken cumulus, while the worst results are for streets of moderately thick cumulus observed at relatively large solar zenith angles. After both p(obs)(tau) and corresponding p(gamma)(tau) are filtered through the IPA; however, resulting solar zenith angle dependent and spherical albedos often agree to well within 5%, regardless of cloud type. Furthermore, disparities between IPA albedos using p(obs)(7) and p(gamma)(tau) are roughly 10 times smaller than disparities between IPA albedos using p(obs)(tau) and corresponding PPH albedos [R(pp)(<(tau)over bar>)]. Thus, for marine boundary layer clouds, the gamma IPA can be expected to remove most of the PPH bias currently present in GCMs. A simple parameterization, dependent on cloud fraction, is furnished that may enable the gamma IPA to be used in GCMs. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA. LOCKHEED MARTIN SCI & ENGN CO,HAMPTON,VA. MCMASTER UNIV,DEPT GEOG,HAMILTON,ON,CANADA. RP Barker, HW (reprint author), ATMOSPHER ENVIRONM SERV,CLOUD PHYS RES DIV,4905 DUFFERIN ST,DOWNSVIEW,ON M3H 5T4,CANADA. NR 25 TC 131 Z9 133 U1 0 U2 9 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD AUG 15 PY 1996 VL 53 IS 16 BP 2304 EP 2316 DI 10.1175/1520-0469(1996)053<2304:APFCGA>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VE238 UT WOS:A1996VE23800002 ER PT J AU Choi, SR Salem, JA AF Choi, SR Salem, JA TI Error identified as hysteresis in flexure testing of advanced ceramics SO SCRIPTA MATERIALIA LA English DT Article C1 CLEVELAND STATE UNIV,CLEVELAND,OH 44115. RP Choi, SR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 10 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 1359-6462 J9 SCRIPTA MATER JI Scr. Mater. PD AUG 15 PY 1996 VL 35 IS 4 BP 491 EP 494 DI 10.1016/1359-6462(96)00175-3 PG 4 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA UX921 UT WOS:A1996UX92100005 ER PT J AU Khakoo, MA Trajmar, S LeClair, LR Kanik, I Csanak, G Fontes, CJ AF Khakoo, MA Trajmar, S LeClair, LR Kanik, I Csanak, G Fontes, CJ TI Differential cross sections for electron impact excitation of Xe .1. Excitation of the five lowest levels; Experiment and theory SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID DISTORTED-WAVE CALCULATION; INCIDENT ENERGIES; NOBLE-GASES; RARE-GASES; SCATTERING; XENON; PARAMETERS; KRYPTON; STATES; REGION AB Experimental and theoretical differential cross sections (DCSs) for electron impact excitation of the five lowest levels of xenon are reported. The experimental data were obtained at impact energies of 10, 15, 20 and 30 eV for scattering angles in the range of 0 degrees to 135 degrees. The scattering intensities for excitation of various levels with respect to that of the combined two lowest levels (representing the corresponding DCS ratios) were measured with conventional electrostatic electron energy-loss spectrometers. Absolute DCSs for excitation of the combined two lowest levels were derived from DCS ratios for excitation of the combined two lowest levels and elastic scattering and utilizing the elastic DCSs of Register et al. These DCS ratios were obtained from scattering intensity ratios measured with conventional electrostatic electron energy-loss spectrometers after correction for instrumental effects by utilizing electron time-of-flight measurements for determining the proper value of this ratio at 90 degrees scattering angle for each impact energy. The unitarized first-order many-body theory and the unitarized distorted-wave approximation were applied to obtain the theoretical differential cross sections for impact energies of 10, 15, 20, 30, 50 and 80 eV. The present experimental and theoretical results are compared with each other and with other available experimental and theoretical DCSs. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87544. RP Khakoo, MA (reprint author), CALIF STATE UNIV FULLERTON,DEPT PHYS,FULLERTON,CA 92634, USA. NR 48 TC 29 Z9 29 U1 1 U2 5 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD AUG 14 PY 1996 VL 29 IS 15 BP 3455 EP 3475 DI 10.1088/0953-4075/29/15/018 PG 21 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA VD866 UT WOS:A1996VD86600018 ER PT J AU Khakoo, MA Trajmar, S Wang, S Kanik, I Aguirre, A Fontes, CJ Clark, REH Abdallah, J AF Khakoo, MA Trajmar, S Wang, S Kanik, I Aguirre, A Fontes, CJ Clark, REH Abdallah, J TI Differential cross sections for electron impact excitation of Xe .2. Excitation of the sixth to twentieth lowest levels; Experiment and theory SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID XENON AB Experimental and theoretical differential cross sections fbr electron impact excitation of Xe are reported for the lowest 6th to 20th levels. These data are an extension of the work discussed in the preceding paper. The theoretical work is based on the unitarized first-order many-body theory and unitarized distorted-wave approximation. The experimental data span the same respective range of electron impact energies and scattering angles as the preceding paper. The present theoretical and experimental data are compared with each other and with other existing experimental data. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87544. RP Khakoo, MA (reprint author), CALIF STATE UNIV FULLERTON,DEPT PHYS,FULLERTON,CA 92634, USA. NR 5 TC 16 Z9 16 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD AUG 14 PY 1996 VL 29 IS 15 BP 3477 EP 3486 DI 10.1088/0953-4075/29/15/019 PG 10 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA VD866 UT WOS:A1996VD86600019 ER PT J AU Holt, RG Trinh, EH AF Holt, RG Trinh, EH TI Faraday wave turbulence on a spherical liquid shell SO PHYSICAL REVIEW LETTERS LA English DT Article ID LIGHT-SCATTERING; SPECTRAL-ANALYSIS; SURFACE-WAVES; FILMS; DROPLET; MODES; RANGE AB Millimeter-radius liquid shells are acoustically levitated in an ultrasonic field. Capillary waves are observed on the shells. At low energies (minimal acoustic amplitude, thick shell) a resonance is observed between the symmetric and antisymmetric thin film oscillation modes. At high energies (high acoustic pressure, thin shell) the shell becomes fully covered with high-amplitude waves. Temporal spectra of scattered light from the shell in this regime exhibit a power-law decay indicative of turbulence. RP Holt, RG (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Holt, Ray/G-5677-2010 NR 28 TC 29 Z9 30 U1 1 U2 3 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 12 PY 1996 VL 77 IS 7 BP 1274 EP 1277 DI 10.1103/PhysRevLett.77.1274 PG 4 WC Physics, Multidisciplinary SC Physics GA VB330 UT WOS:A1996VB33000021 ER PT J AU Han, D Kim, YS Noz, ME AF Han, D Kim, YS Noz, ME TI Polarization optics and bilinear representation of the Lorentz group SO PHYSICS LETTERS A LA English DT Article ID STATES; LIGHT AB It is shown that the bilinear representation of the Lorentz group is the natural language for the polarization of light. The combined effect of attenuation and phase-shift filters leads to a two-by-two representation of the Lorentz group, which can then be translated into the bilinear representation. The coherency matrix is a representation of the six-parameter Lorentz group. C1 UNIV MARYLAND,DEPT PHYS,COLLEGE PK,MD 20742. NYU,DEPT RADIOL,NEW YORK,NY 10016. RP Han, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 9101,GREENBELT,MD 20771, USA. NR 18 TC 14 Z9 14 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0375-9601 J9 PHYS LETT A JI Phys. Lett. A PD AUG 12 PY 1996 VL 219 IS 1-2 BP 26 EP 32 DI 10.1016/0375-9601(96)00424-0 PG 7 WC Physics, Multidisciplinary SC Physics GA VD421 UT WOS:A1996VD42100005 ER PT J AU Dodelson, S Gates, E Stebbins, A AF Dodelson, S Gates, E Stebbins, A TI Cold plus hot dark matter and the cosmic microwave background SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology, theory; dark matter; elementary particles ID LARGE-SCALE STRUCTURE; RADIATION ANISOTROPY; EXPANDING UNIVERSE; REIONIZATION; FLUCTUATIONS; MAPS AB We examine the cosmic microwave background power spectrum for adiabatic models with a massive neutrino component. We present the results of a detailed numerical evolution of cold + hot dark matter (CHDM) models and compare these results with the standard cold dark matter (CDM) spectrum. The difference is of order 5%-10% for 400 < l < 1000 for currently popular CHDM models. Using semianalytic approximations, we also discuss the relevant physics involved. Finally, we remark on the ability of future experiments to differentiate between these models. An all-sky experiment with a beam size smaller than 30' can distinguish between CHDM and CDM if other cosmological parameters are known. Even allowing other parameters to vary, it may be possible to distinguish CDM from CHDM. C1 UNIV CHICAGO, DEPT ASTRON & ASTROPHYS, ENRICO FERMI INST, CHICAGO, IL 60637 USA. RP Dodelson, S (reprint author), FERMILAB NATL ACCELERATOR LAB, NASA, FERMILAB ASTROPHYS CTR, BATAVIA, IL 60510 USA. NR 37 TC 89 Z9 89 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 AUG 10 PY 1996 VL 467 IS 1 BP 10 EP 18 DI 10.1086/177581 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB703 UT WOS:A1996VB70300002 ER PT J AU Ford, E Kaaret, P Harmon, BA Tavani, M Zhang, SN AF Ford, E Kaaret, P Harmon, BA Tavani, M Zhang, SN TI A search for hard X-ray emission from globular clusters: Constraints from BATSE SO ASTROPHYSICAL JOURNAL LA English DT Article DE globular clusters, general; pulsars, general; X-rays, bursts; X-rays, stars ID HIDDEN MILLISECOND PULSARS; OMEGA-CENTAURI; UPPER LIMITS; GAMMA-RAYS; SKY SURVEY; 47-TUCANAE; BURSTER; DISCOVERY; TELESCOPE; EVOLUTION AB We have monitored a sample of 27 nearby globular clusters in the hard X-ray band (20-120 keV) for similar to 1400 days using the BATSE instrument on board the Compton Gamma Ray Observatory. Globular clusters may contain a large number of compact objects (e.g., pulsars or X-ray binaries containing neutron stars) that can produce hard X-ray emission. Our search provides a sensitive (similar to 50 mCrab) monitor for hard X-ray transient events on timescales of greater than or similar to 1 day, as well as a means for observing persistent hard X-ray emission. We have discovered no transient events from any of the clusters and no persistent emission. Our observations include a sensitive search of four nearby clusters containing dim X-ray sources: 47 Tucanae, NGC 5139, NGC 6397, and NGC 6752. The nondetection in these clusters implies a lower limit for the recurrence time of transients of 2-6 yr for events with luminosities greater than or similar to 10(36) ergs s(-1) (20-120 keV) and similar to 20 yr if the sources in these clusters are taken collectively. This suggests that the dim X-ray sources in these clusters are not transients similar to Aql X-l. We also place upper limits on the persistent emission in the range (2-10) x 10(34) ergs s(-1) (2 sigma, 20-120 keV) for these four clusters. For 47 Tuc, the upper limit is more sensitive than previous measurements by a factor of 3. We find a model-dependent upper limit of 19 isolated millisecond pulsars producing gamma rays in 47 Tuc, compared to the 11 observed radio millisecond pulsars in this cluster. C1 COLUMBIA ASTROPHYS LAB,NEW YORK,NY 10027. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV HUNTSVILLE,SPACE RES ASSOC,MSFC,HUNTSVILLE,AL 35812. RP Ford, E (reprint author), COLUMBIA UNIV,DEPT PHYS,538 W 120TH ST,NEW YORK,NY 10027, USA. OI Tavani, Marco/0000-0003-2893-1459 NR 58 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1996 VL 467 IS 1 BP 272 EP 279 DI 10.1086/177602 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB703 UT WOS:A1996VB70300023 ER PT J AU Canuto, VM AF Canuto, VM TI Turbulent convection: Old and new models SO ASTROPHYSICAL JOURNAL LA English DT Article DE convection; stars, interiors; turbulence ID REYNOLDS STRESS APPROACH; ROTATION; TESTS AB This paper contains (1) a physical argument to show that the one-eddy MLT model underestimates the convective flux F-c in the high-efficiency regime, while it overestimates F-c in the low-efficiency regime, and (2) a new derivation of the F-c(MLT) using a turbulence model in the one-eddy approximation. (3) We forsake the one-eddy approximation and adopt the Kolmogorov spectrum to represent the turbulent energy spectrum. The resulting F-c > F-c(MLT) in the high-efficiency regime, and F-c < F-c(MLT) in the low-efficiency case, are in agreement with the physical arguments concerning the one-eddy MLT model. (4) By forsaking the Kolmogorov model and solving a two-point closure model, one obtains the CM model. The F-c(CM) satisfies (1). F-c(CM) corresponds to a ''tilt'' in efficiency space of F-c(MLT), an effect that cannot be achieved by changing alpha. We discuss the astrophysical tests of the CM model. (5) Concerning the laboratory turbulent convection, we show that the CM model provides a better fit than the MLT to recent high Rayleigh number (Ra) laboratory data on convection. (6) Concerning nonlocal convection, the most complete model available is the one-point closure model (Reynolds stress model), which entails five differential equations for the five second-order moments. We present the solution corresponding to the local, stationary case. The results are expressed analytically in terms of Ko (Kolmogorov constant), Pe (Peclet number), and S (convective efficiency). (7) We find that the superadiabatic temperature gradient is given by -partial derivative T/partial derivative r - c(p)(-1)g(r) where the renormalized g(r) = g(1 + g(-1)rho(-1) dpt(d)/dz) and p(t) is the turbulent pressure. This result, which follows naturally from the Reynolds stress approach, contrasts with previous empirical suggestions to include p(t). (8) We derive new expressions for the turbulence pressure using two different turbulence models and (9) we show that the often used Kolmogorov-Prandtl expression for the turbulent diffusivity is valid only in the high convective efficiency limit. We derive a new expression valid for arbitrary Peclet numbers. (10) We derive an expression for the flux conservation law, which includes F(KE), the flux of turbulent kinetic energy, a third-order moment for which we provide a new expression. (11) No model has thus far accounted for the influence on F-c due to the presence of a stable layer (radiative layer) bordering the convective zone. We work out the first such model, and (12) we discuss topics for future research. RP Canuto, VM (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 35 TC 32 Z9 32 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1996 VL 467 IS 1 BP 385 EP 396 DI 10.1086/177613 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB703 UT WOS:A1996VB70300034 ER PT J AU Ebisawa, K Ueda, Y Inoue, H Tanaka, Y White, NE AF Ebisawa, K Ueda, Y Inoue, H Tanaka, Y White, NE TI ASCA observations of the iron line structure in Cygnus X-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; stars, emission-line, Be; stars, individual (Cygnus X-1); X-rays, stars ID X-RAY-SPECTRUM; ACCRETION DISK; BLACK-HOLE; COMPTON REFLECTION; COLD MATTER; GAMMA-RAYS; EMISSION; FLUORESCENCE; ABUNDANCES; ELEMENTS AB The black hole candidate Cyg X-l was observed with the ASCA satellite on multiple occasions in 1993 and 1994 for a total exposure of about 7 days. The energy resolution of the ASCA SIS (Delta E/E approximate to 2% at 6 keV) allows the spectral structure in the iron K band to be studied in greater detail than before. We detected an iron emission line at 6.4 keV in almost all the data with an intrinsic line width of less than or similar to 0.2 keV (1 sigma) and an equivalent width of 10-30 eV. The line parameters show no clear orbital phase dependence. A broad edge feature was observed at E greater than or similar to 7 keV in all the spectra. Both the narrow iron emission-line and broad edge features are consistent with disk reflection from the outer parts of an ionized accretion disk where the most populous iron ion species is Fe XI. C1 INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. RP Ebisawa, K (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 63 TC 121 Z9 121 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1996 VL 467 IS 1 BP 419 EP 434 DI 10.1086/177616 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB703 UT WOS:A1996VB70300037 ER PT J AU LaRosa, TN Moore, RL Miller, JA Shore, SN AF LaRosa, TN Moore, RL Miller, JA Shore, SN TI New promise for electron bulk energization in solar flares: Preferential Fermi acceleration of electrons over protons in reconnection-driven magnetohydrodynamic turbulence SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; MHD; Sun, flares; Sun, particle emission; turbulence ID LOW-BETA PLASMA; WAVES; PHASE AB The hard X-ray luminosity of impulsive solar flares indicates that electrons in the low corona are bulk energized to energies of order 25 keV. LaRosa & Moore pointed out that the required bulk energization could be produced by cascading MHD turbulence generated by Alfvenic outflows from sites of strongly driven reconnection. LaRosa, Moore, gr Shore proposed that the compressive component of the cascading turbulence dissipates into the electrons via Fermi acceleration. However, for this to be a viable electron bulk energization mechanism, the rate of proton energization by the same turbulence cannot exceed the electron energization rate. In this paper we estimate the relative efficiency of electron and proton Fermi acceleration in the compressive MHD turbulence expected in the reconnection outflows in impulsive solar flares. We find that the protons pose no threat to the electron energization. Particles extract energy from the MHD turbulence by mirroring on magnetic compressions moving along the magnetic field at the Alfven speed. The mirroring rate, and hence the energization rate, is a sensitive function of the particle velocity distribution. In particular, there is a lower speed limit V-min approximate to V-A, below which the pitch-angle distribution of the particles is so highly collapsed to the magnetic field in the frame of the magnetic compressions that there is no mirroring and hence no Fermi acceleration. For coronal conditions, the proton thermal speed is much less than the Alfven speed and proton Fermi acceleration is negligible. In contrast, nearly all of the electrons are super-Alfvenic, so their pitch-angle distribution is nearly isotropic in the frame of the magnetic compressions. Consequently, the electrons are so vigorously mirrored that they are Fermi accelerated to hard X-ray energies in a few tenths of a second by the magnetic compressions on scales of 10(5)-10(3) cm in the cascading MHD turbulence. We conclude that dissipation of reconnection-generated MHD turbulence by electron Fermi acceleration plausibly accounts for the electron bulk energization in solar flares. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SOLAR PHYS BRANCH, HUNTSVILLE, AL 35812 USA. UNIV ALABAMA, DEPT PHYS, HUNTSVILLE, AL 35899 USA. INDIANA UNIV, DEPT PHYS & ASTRON, S BEND, IN 46615 USA. RP LaRosa, TN (reprint author), KENNESAW STATE COLL, DEPT BIOL & PHYS SCI, MARIETTA, GA 30061 USA. NR 46 TC 32 Z9 32 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1996 VL 467 IS 1 BP 454 EP 464 DI 10.1086/177619 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB703 UT WOS:A1996VB70300040 ER PT J AU Lau, YT Siregar, E AF Lau, YT Siregar, E TI Nonlinear alfven wave propagation in the solar wind (vol 465, pg 451, 1996) SO ASTROPHYSICAL JOURNAL LA English DT Correction AB We derive a self-consistent set of equations that describe the propagation of nonlinear shear Alfven waves in the solar wind. The equations include the interaction between the waves and wind plasmas and has an exact energy conservation law. Using a truncated Fourier series, we further reduce the system to a simplifed nonlinear model with multiple waves. We solve the model numerically in a radially expanding box with a finite angular size. We find that for linear waves in a time-varying plasma background, the conditions for the WKB approximation are violated in practically the entire radial domain (even at high frequencies), although the scaling of wave amplitudes (delta B) with radial distance and the equipartition between the magnetic and kinetic energy are similar to the WKB results. For nonlinear waves, equipartition still holds, but nonlinear wave reflection enhances the backward propagating waves (in the rest frame of the wind), which leads to a faster drop in delta B than the linear waves. As a result, there is a ''soft'' saturation in which delta B approaches the background magnetic field gradually at large distance. The simplified nonlinear model produces reasonably high wind speed (between 600 and 700 km s(-1)). C1 NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. RP Lau, YT (reprint author), UNIV MARYLAND, INST PLASMA RES, COLLEGE PK, MD 20742 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1996 VL 467 IS 1 BP 474 EP 474 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB703 UT WOS:A1996VB70300044 ER PT J AU Hof, M Menn, W Pfeifer, C Simon, M Golden, RL Stochaj, SJ Stephens, SA Basini, G Ricci, M Brancaccio, FM Papini, P Piccardi, S Spillantini, P DePascale, MP Morselli, A Picozza, P Brunetti, MT Codino, A Grimani, C Menichelli, M Mitchell, JW Ormes, JF Streitmatter, RE AF Hof, M Menn, W Pfeifer, C Simon, M Golden, RL Stochaj, SJ Stephens, SA Basini, G Ricci, M Brancaccio, FM Papini, P Piccardi, S Spillantini, P DePascale, MP Morselli, A Picozza, P Brunetti, MT Codino, A Grimani, C Menichelli, M Mitchell, JW Ormes, JF Streitmatter, RE TI Measurement of cosmic-ray antiprotons from 3.7 to 19 GeV SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; elementary particles ID SPECTROMETER; PERFORMANCE; RADIATION; RATIO AB The antiproton-to-proton ratio, (p) over bar/p, in cosmic rays has been measured in the energy range 3.7-19 GeV. This measurement was carried out using a balloon-borne superconducting magnetic spectrometer along with a gas Cerenkov counter, an imaging calorimeter, and a time-of-flight scintillator system. The measured (p) over bar/p ratio was determined to be 1.24(-0.51)(+0.68) x 10(-4). The present result, along with other recent observations, shows that the observed abundances of antiprotons are consistent with models in which antiprotons are produced as secondaries during the propagation of cosmic rays in the Galaxy. C1 NEW MEXICO STATE UNIV,LAS CRUCES,NM 88003. TATA INST FUNDAMENTAL RES,BOMBAY 400005,MAHARASHTRA,INDIA. IST NAZL FIS NUCL,LAB NAZL FRASCATI,I-00044 FRASCATI,ITALY. UNIV FLORENCE,DIPARTIMENTO FIS,I-50125 FLORENCE,ITALY. IST NAZL FIS NUCL,SEZ FIRENZE,I-50125 FLORENCE,ITALY. UNIV ROMA TOR VERGATA,DIPARTIMENTO FIS,I-00133 ROME,ITALY. IST NAZL FIS NUCL,SEZ ROMA,I-00133 ROME,ITALY. UNIV PERUGIA,DIPARTIMENTO FIS,I-06100 PERUGIA,ITALY. IST NAZL FIS NUCL,SEZ PERUGIA,I-06100 PERUGIA,ITALY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Hof, M (reprint author), UNIV SIEGEN,D-57068 SIEGEN,GERMANY. RI Morselli, Aldo/G-6769-2011 OI Morselli, Aldo/0000-0002-7704-9553 NR 16 TC 55 Z9 55 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1996 VL 467 IS 1 BP L33 EP L36 DI 10.1086/310185 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB702 UT WOS:A1996VB70200009 ER PT J AU Martin, JML Lee, TJ AF Martin, JML Lee, TJ TI Accurate ab initio quartic force field and vibrational frequencies of the NH4+ ion and its deuterated forms SO CHEMICAL PHYSICS LETTERS LA English DT Article ID AMMONIUM ION; TRIPLE EXCITATIONS; BASIS-SETS; HARMONIC FREQUENCIES; LASER SPECTROSCOPY; MOLECULAR-IONS; WAVE-FUNCTIONS; BAND; CONSTANTS; HYDROGEN AB The quartic force field of NH: has been computed using advanced coupled cluster methods and a basis set of spdf quality. Effects of further basis set extension and of the inclusion of core correlation on the geometry and harmonic frequencies have been investigated. Our best computed values are: r(e) = 1.02029 Angstrom, v(1) = 3236.6, v(2) = 1690.1, v(3) = 3345.1, and v(4) - 1447.2 cm(-1), in excellent agreement with the experimental data. Complete sets of fundamentals and anharmonicity constants are reported for NH3D+, NH2D2+ NHD3+, and ND4+. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Martin, JML (reprint author), HEBREW UNIV JERUSALEM,INST CHEM,IL-91904 JERUSALEM,ISRAEL. RI Lee, Timothy/K-2838-2012; Martin, Jan/A-7457-2008 OI Martin, Jan/0000-0002-0005-5074 NR 33 TC 45 Z9 45 U1 1 U2 6 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 AUG 9 PY 1996 VL 258 IS 1-2 BP 129 EP 135 DI 10.1016/0009-2614(96)00679-3 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA VB494 UT WOS:A1996VB49400020 ER PT J AU Martin, JML Lee, TJ AF Martin, JML Lee, TJ TI The atomization energy and proton affinity of NH3. An ab initio calibration study SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CONSISTENT BASIS-SETS; GAUSSIAN-BASIS SETS; HARMONIC FREQUENCIES; WAVE-FUNCTIONS; FORCE-FIELDS; MOLECULES; HEATS; THERMOCHEMISTRY; PERFORMANCE; GEOMETRIES AB The total atomization energy and proton affinity of NH3 have been subjected to an extensive convergence study involving basis sets of up to spdfgh quality. Our best extrapolated Sigma D-o = 276.5 kcal/mol lies only 0.2 kcal/mol below the experimental value. Our recommended value for PA(298), 203.9+/-0.3 kcal/mol, is in excellent agreement with the most recent experimental value but has a smaller error margin. It is found that augmented basis sets are desirable when determining proton affinities using the empirical correction for further basis set expansion proposed in J. Chem. Phys. 97 (1992) 5012. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Martin, JML (reprint author), HEBREW UNIV JERUSALEM,INST CHEM,IL-91904 JERUSALEM,ISRAEL. RI Lee, Timothy/K-2838-2012; Martin, Jan/A-7457-2008 OI Martin, Jan/0000-0002-0005-5074 NR 35 TC 122 Z9 122 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD AUG 9 PY 1996 VL 258 IS 1-2 BP 136 EP 143 DI 10.1016/0009-2614(96)00658-6 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA VB494 UT WOS:A1996VB49400021 ER PT J AU Garg, VK Gaugler, RE AF Garg, VK Gaugler, RE TI Leading edge film-cooling effects on turbine blade heat transfer SO NUMERICAL HEAT TRANSFER PART A-APPLICATIONS LA English DT Article ID JET AB A three-dimensional Navier-Stokes code has been used to study the effect of spanwise pitch of shower-head holes and coolant to mainstream mass flow ratio on the adiabatic effectiveness and heat transfer coefficient on a film-cooled turbine vane. The mainstream is akin to that under real engine conditions with stagnation temperature 1900 K and stagnation pressure 3 MPa. It if found that with the ratio of coolant to mainstream mass flow being fixed, reducing the spanwise pitch for shower-head holes (P) from 7.5d to 3.0d, where d is the hole diameter, increases the average effectiveness considerably over the blade surface. However, when P/d = 7.5, increasing the coolant mass flow increases the effectiveness on the pressure surface but reduces a oil the suction surface owing to coolant jet lift-off For P/d = 4.5 or 3.0 such an anomaly does not occur within the range of coolant-to-mainstream-mass-flow ratios analyzed. In all cases, adiabatic effectiveness and heat transfer coefficient are highly three-dimensional. C1 NASA,LEWIS RES CTR,INTERNAL FLUID MECH DIV,TURBOMACHINERY FLOW PHYS BRANCH,CLEVELAND,OH 44135. RP Garg, VK (reprint author), NASA,LEWIS RES CTR,AYT CORP,MAILSTOP 5-11,CLEVELAND,OH 44135, USA. NR 30 TC 23 Z9 25 U1 1 U2 1 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 1040-7782 J9 NUMER HEAT TR A-APPL JI Numer. Heat Tranf. A-Appl. PD AUG 9 PY 1996 VL 30 IS 2 BP 165 EP & DI 10.1080/10407789608913834 PG 24 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA VE678 UT WOS:A1996VE67800004 ER PT J AU Smith, GD Jaffe, RL Yoon, DY AF Smith, GD Jaffe, RL Yoon, DY TI Conformational characteristics of 1,3-dimethoxypropane and poly(oxytrimethylene) based upon ab initio electronic structure calculations SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID MODEL MOLECULES; 1,2-DIMETHOXYETHANE; SOLVENT; SIMULATIONS; ENERGY; GAS AB In this paper we extend our study of the conformational properties of poly(alkyl ethers) by considering poly(oxytrimethylene) (POM(3)). The conformational energies and geometries of the important conformers of the model molecule 1,3-dimethoxypropane (DMP) were determined from ab initio electronic structure calculations. Predicted NMR vicinal coupling constants in DMP, using conformational populations determined from quantum chemical energies calculated at the MP2 level with a D95+(2df,p) basis set, are in good agreement with experimental gas phase values. The conformer energies and geometries of DMP from quantum chemistry calculations have been utilized in developing a second-order rotational isomeric state (RIS) model for poly(oxytrimethylene) (POM(3)). Values obtained for the first-order O-C-C-C gauche energy E sigma (-1.0 kcal/ mel) and the second-order O-C-C-C-O gi(+/-) g(-/+) energy E(omega'') (4.0 kcal/mol) differ significantly from values in previous RIS models that were parametrized to reproduce experimental data on POM(3) and DMP in solutions. Our model yields values for the characteristic ratio in fair agreement with experiment, but its temperature coefficient and mean-square dipole moment values are in poorer agreement than those obtained from quantum chemistry based RIS models derived for other polyethers. This discrepancy is attributed mainly to significant contributions from polymer-solvent interactions which depend on local chain conformations and the temperature dependence of such condensed phase effects in POM(3) solutions. C1 IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. UNIV MISSOURI,DEPT CHEM ENGN,COLUMBIA,MO 65211. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 19 TC 15 Z9 15 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD AUG 8 PY 1996 VL 100 IS 32 BP 13439 EP 13446 DI 10.1021/jp952401k PG 8 WC Chemistry, Physical SC Chemistry GA VB315 UT WOS:A1996VB31500019 ER PT J AU Mielke, SL Allison, TC Truhlar, DG Schwenke, DW AF Mielke, SL Allison, TC Truhlar, DG Schwenke, DW TI Quantum mechanical rate coefficients for the Cl+H-2 reaction SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID POTENTIAL-ENERGY SURFACE; TRANSITION-STATE THEORY; WAVE VARIATIONAL PRINCIPLE; MANY-BODY EXPANSION; KINETIC-ISOTOPE; RATE CONSTANTS; CHEMICAL-REACTIONS; SCATTERING; PROBABILITIES; DYNAMICS AB We present quantal reaction rate coefficients obtained from well-converged cumulative reaction probabilities calculated by an algebraic variational method for total angular momentum J in the range 0-6 and obtained from the separable-rotation approximation for J not equal 6. These results are used to test variational transition state theory calculations with optimized multidimensional tunneling contributions and are compared to experiment. C1 UNIV MINNESOTA,DEPT CHEM,CHEM PHYS PROGRAM,MINNEAPOLIS,MN 55455. UNIV MINNESOTA,INST SUPERCOMP,MINNEAPOLIS,MN 55455. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Mielke, Steven/B-7533-2008; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Mielke, Steven/0000-0002-1938-7503; Truhlar, Donald/0000-0002-7742-7294 NR 56 TC 75 Z9 76 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD AUG 8 PY 1996 VL 100 IS 32 BP 13588 EP 13593 DI 10.1021/jp960782b PG 6 WC Chemistry, Physical SC Chemistry GA VB315 UT WOS:A1996VB31500039 ER PT J AU Thorn, RP Payne, WA Stief, LJ Tardy, DC AF Thorn, RP Payne, WA Stief, LJ Tardy, DC TI Rate constant and product branching for the vinyl radical self reaction at T=298 K SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID DENSE INTERSTELLAR CLOUDS; ABSOLUTE RATE-CONSTANT; GAS-PHASE; TEMPERATURE-DEPENDENCE; MOLECULAR-OXYGEN; KINETIC DATA; C2H3; ATMOSPHERES; ABSORPTION; PHOTOLYSIS AB The rate constant and product branching for the self reaction of C2H3 has been measured using the discharge-flow kinetic technique coupled to mass spectrometric detection at T = 298 K and 1 Torr nominal pressure (He). C2H3 is produced by the reaction of F with C2H4, which also forms C2H3F + H. In addition to the C2H3 self reaction, C2H3 also decays by reaction with H and by wall loss processes. The result obtained by parameter fitting the C2H3 decay curves was k(C2H3 + C2H3) = (1.41 +/- 0.60) x 10(-10) cm(3) molecule(-1) s(-1), where k is defined by d[C2H3]/dt = 2k[C2H3](2). Results from the product studies showed that the recombination product 1,3-butadiene was not observed at 1 Torr and that the ratio [C2H2] product formed/[C2H3](0) was 0.65 +/- 0.14 for the combined C2H3 + C2H3 and C2H3 + H reactions. Both observations are consistent with C2H2 + C2H4 being the exclusive C2H3 + C2H3 products, since the maximum yield of C2H2 from the combined C2H3 + C2H3 and C2H3 + H reactions is 0.59. The experimental observations that k(1) is independent of pressure and that no 1,3-butadiene (product of C2H3 combination) is observed at 1 Torr pressure requires a mechanism in which the chemically activated 2,3-butadiene undergoes a unimolecular reaction. II is postulated that the 1,3-butadiene first isomerizes to cyclobutene, which then unimolecularly decomposes to C2H2 and C2H4. Although the former reaction is well documented, the latter reaction has not been previously reported. RRKM calculations predict a pressure dependence similar to what is experimentally observed. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV IOWA,DEPT CHEM,IOWA CITY,IA 52242. NR 66 TC 24 Z9 24 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD AUG 8 PY 1996 VL 100 IS 32 BP 13594 EP 13602 DI 10.1021/jp960825o PG 9 WC Chemistry, Physical SC Chemistry GA VB315 UT WOS:A1996VB31500040 ER PT J AU Bauschlicher, CW Partridge, H AF Bauschlicher, CW Partridge, H TI The electronic excited states of BN SO CHEMICAL PHYSICS LETTERS LA English DT Article ID BASIS-SETS; ABINITIO CALCULATIONS; WAVE-FUNCTIONS; DIMER AB The a(1) Sigma(+)-X(3)II separation is estimated to be 180 +/- 110 cm(-1), which is in reasonable agreement with the recent experimental determination that the separation in a neon matrix is between 15 and 182 cm(-1). The calculated spectroscopic constants for the excited states confirm the experimental assignment for the triplet states below 30000 cm(-1) and two lowest singlet states. On the basis of a comparison of the computed results with those obtained from experiment, the computed spectroscopic constants for the higher electronic states should be sufficiently accurate to help in the assignment of future experiments. RP Bauschlicher, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 18 TC 36 Z9 36 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD AUG 2 PY 1996 VL 257 IS 5-6 BP 601 EP 608 DI 10.1016/0009-2614(96)00576-3 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA VA859 UT WOS:A1996VA85900030 ER PT J AU Linderman, JK Talmadge, RJ Gosselink, KL Tri, PN Roy, RR Grindeland, RE AF Linderman, JK Talmadge, RJ Gosselink, KL Tri, PN Roy, RR Grindeland, RE TI Synergistic ablation does not affect atrophy or altered myosin heavy chain expression in the non-weight bearing soleus muscle SO LIFE SCIENCES LA English DT Article DE hypertrophy; hindlimb suspension; muscle plasticity; myofibrillar protein; myosin isoforms; rats ID INTERSTITIAL FLUID VOLUME; HINDLIMB-SUSPENDED RATS; SKELETAL-MUSCLE; GROWTH-HORMONE; BIOCHEMICAL-PROPERTIES; RESISTANCE EXERCISE; ISOFORM EXPRESSION; FAST-TWITCH; SUSPENSION; PLANTARIS AB The purpose of this study was to investigate whether the soleus muscle undergoes atrophy and alterations in myosin heavy chain (MHC) composition during non-weight bearing in the absence of synergists. Thirty-two female rats were randomly assigned to four groups: control (C), synergistic ablation (ABL) of the gastrocnemius and plantaris muscles to overload the soleus muscle, hindlimb suspension (HLS), or a combination of synergistic ablation and hindlimb suspension (HLS-ABL). After 28 days of hindlimb suspension, soleus atrophy was more pronounced in HLS (58%) than in HLS-ABL (43%) rats. Compared to C rats, non-weight bearing decreased mixed and myofibrillar protein contents and Type I MHC 49%, 45%, and 7%, respectively, in HLS animals. In addition, de novo expression of fast Type IIx and Type IIb MHC (5% and 2%, respectively) was observed in HLS animals. Similarly, when compared to C rats, mixed and myofibrillar protein contents and Type I MHC decreased 43%, 46%, and 4%, respectively, in HLS-ABL animals. Also, de novo expression of Type IIx (4%) and IIb (1%) MHC was observed. Collectively, these data indicate that the loss of muscle protein and Type I MHC, and the de novo expression of Type IIx and Type IIb MHC in the rat soleus occur independently of the presence of synergists during non-weight bearing. Furthermore, these results confirm the contention that soleus mass and MHC expression are highly sensitive to alterations in mechanical load. C1 UNIV CALIF LOS ANGELES,DEPT PHYSIOL SCI,LOS ANGELES,CA 90024. UNIV CALIF LOS ANGELES,BRAIN RES INST,LOS ANGELES,CA 90024. RP Linderman, JK (reprint author), NASA,AMES RES CTR,LIFE SCI DIV 23911,MOFFETT FIELD,CA 94035, USA. FU NIDCR NIH HHS [DE07212] NR 27 TC 9 Z9 9 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0024-3205 J9 LIFE SCI JI Life Sci. PD AUG 2 PY 1996 VL 59 IS 10 BP 789 EP 795 DI 10.1016/0024-3205(96)00369-4 PG 7 WC Medicine, Research & Experimental; Pharmacology & Pharmacy SC Research & Experimental Medicine; Pharmacology & Pharmacy GA VB018 UT WOS:A1996VB01800002 PM 8761312 ER PT J AU Goldberg, B AF Goldberg, B TI More green for NASA SO AEROSPACE AMERICA LA English DT Article RP Goldberg, B (reprint author), NASA MARSHALL,SOLID PROP BRANCH,WASHINGTON,DC 20546, USA. NR 0 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 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD AUG PY 1996 VL 34 IS 8 BP 34 EP 38 PG 5 WC Engineering, Aerospace SC Engineering GA VA866 UT WOS:A1996VA86600011 ER PT J AU Tso, TL Leu, MT AF Tso, TL Leu, MT TI Quantitative analysis of the infrared absorptivities of nitric acid ices aerosol existing in polar stratospheric clouds SO ANALYTICAL SCIENCES LA English DT Article DE infrared absorptivity; nitric acid ice; polar stratospheric cloud; remote sensing; Fourier-transform infrared spectroscopy ID HETEROGENEOUS REACTIONS; VAPOR-PRESSURES; HYDROGEN-BOND; OZONE HOLE; WATER ICE; TRIHYDRATE; FILMS; PARTICLES; SPECTRA; ION AB The infrared absorptivities of nitric acid ices formed from vapors containing water and nitric acid were investigated by means of a Fourier-transform infrared spectrometer operated at a wavelength resolution of 1.0 cm(-1) (triangular apodization). The solid films were prepared on the surface of a gold-coated, polished copper plate at a temperature of 153 K to 198 K. After collecting the infrared spectra, the substrates were vaporized and condensed into a U-tube for quantitative analyses of H2O and HNO3 using a quadrupole mass spectrometer. Amorphous forms of nitric acid ices and four crystalline hydrates (nitric acid monohydrate (NAM), nitric acid dihydrate (NAD), and nitric acid trihydrate (both alpha-NAT and beta-NAT forms)) were identified and their infrared absorptivities measured. The infrared spectra were interpreted in terms of the known spectra of oxonium and nitrate ions. Possible implications for remote sensing and the analysis of polar stratospheric clouds using these infrared spectra are discussed. C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. RP Tso, TL (reprint author), NATL TSING HUA UNIV,DEPT CHEM,HSINCHU 30034,TAIWAN. NR 33 TC 12 Z9 12 U1 0 U2 2 PU JAPAN SOC ANALYTICAL CHEM PI TOKYO PA 26-2 NISHIGOTANDA 1 CHOME SHINAGAWA-KU, TOKYO 141, JAPAN SN 0910-6340 J9 ANAL SCI JI Anal. Sci. PD AUG PY 1996 VL 12 IS 4 BP 615 EP 622 DI 10.2116/analsci.12.615 PG 8 WC Chemistry, Analytical SC Chemistry GA VB473 UT WOS:A1996VB47300014 ER PT J AU PloutzSnyder, LL Tesch, PA Hather, BM Dudley, GA AF PloutzSnyder, LL Tesch, PA Hather, BM Dudley, GA TI Vulnerability to dysfunction and muscle injury after unloading SO ARCHIVES OF PHYSICAL MEDICINE AND REHABILITATION LA English DT Article ID WEEK HINDLIMB SUSPENSION; LOWER-LIMB SUSPENSION; SKELETAL-MUSCLE; HUMAN QUADRICEPS; SOLEUS MUSCLE; EXERCISE; STRENGTH; DAMAGE; IMMOBILIZATION; INDEXES AB Objective: To test whether unloading increases vulnerability to eccentric exercise-induced dysfunction and muscle injury. Design: Before-after trial. Setting: General community. Patients or Other Participants: Two women and 5 men (73+/-3kg [mean+/-SE]) who were active college students but were not trained in lower body resistance exercise volunteered. Intervention: Five weeks of unilateral lower limb suspension (ULLS), which has been shown to decrease strength and size of the unloaded, left, but not load-bearing, right quadriceps femoris muscle group (QF) by 20% and 14%, respectively; performance of 10 sets of ten eccentric actions with each QF immediately after the ULLS strength tests with a load equivalent to 65% of the post-ULLS eccentric 1-repetition maximum. Main Outcome Measure(s): Concentric and eccentric 1-repetition maximum for the left, unloaded and the right, load-bearing QF measured immediately after ULLS and 1, 4, 7, 9, and 11 days later; cross-sectional area and spin-spin relaxation time (T2) of each QF as determined by magnetic resonance imaging and measured the last day of ULLS and 3 days later. Results: The mean load used for eccentric exercise was 23+/-2 and 30+/-3kg for the left, unloaded and right, load-bearing QF, respectively. The concentric and eccentric 1-repetition maximum for the unloaded and already weakened left QF was further decreased by 18% (p =.000) and 27% (p =.000), respectively, 1 day after eccentric exercise. Strength did not return to post-ULLS levels until 7 days of recovery. The right, load-bearing QF showed a 4% decrease (p =.002) in the eccentric 1-repetition maximum 1 day after eccentric exercise, The left, unloaded QF showed an increase in T2 (p =.002) in 18% of its cross-sectional area 3 days after the eccentric exercise, thus indicating muscle injury. The right, load-bearing QF showed no elevation in T2 (p =.280). Conclusion: Unloading increases vulnerability to eccentric exercise-induced dysfunction and muscle injury, even at relatively light loads. (C) 1996 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine ann Rehabilitation. C1 OHIO UNIV,DEPT BIOL SCI,ATHENS,OH 45701. KAROLINSKA INST,DEPT PHYSIOL & PHARMACOL,STOCKHOLM,SWEDEN. NASA,KENNEDY SPACE CTR,FL. BIONET CORP,KENNEDY SPACE CTR,FL. NR 43 TC 46 Z9 47 U1 0 U2 0 PU W B SAUNDERS CO PI PHILADELPHIA PA INDEPENDENCE SQUARE WEST CURTIS CENTER, STE 300, PHILADELPHIA, PA 19106-3399 SN 0003-9993 J9 ARCH PHYS MED REHAB JI Arch. Phys. Med. Rehabil. PD AUG PY 1996 VL 77 IS 8 BP 773 EP 777 DI 10.1016/S0003-9993(96)90255-5 PG 5 WC Rehabilitation; Sport Sciences SC Rehabilitation; Sport Sciences GA VA965 UT WOS:A1996VA96500006 PM 8702370 ER PT J AU Ledlow, MJ Loken, C Burns, JO Hill, JM White, RA AF Ledlow, MJ Loken, C Burns, JO Hill, JM White, RA TI Redshifts and optical properties for a statistically complete sample of poor galaxy clusters SO ASTRONOMICAL JOURNAL LA English DT Article ID COMPACT-GROUPS; X-RAY; ROSAT OBSERVATIONS; RICH CLUSTERS; CD GALAXIES; KINEMATICS AB From the poor cluster catalog of White ct al. (1996), we define a sample of 71 optically-selected poor galaxy clusters. The surface-density enhancement we require for our clusters falls between that of the loose associations of Turner & Gott [AJ, 91, 204 (1976)] and the Hickson compact groups [Hickson, ApJ, 255, 382 (1982)]. We review the selection biases and determine the statistical completeness of the sample. For this sample, we report new velocity measurements made with the ARC 3.5-m Dual-Imaging spectrograph and the 2.3-m Steward Observatory MX fiber spectrograph. Combining our own measurements with those from the literature, we examine the velocity distributions, velocity dispersions, and 1D velocity substructure for our poor cluster sample, and compare our results to other poor cluster samples. We find that approximately half of the sample may have significant 1D velocity substructure. The optical morphology, large-scale environment, and velocity field of many of these clusters are indicative of young, dynamically evolving systems. In future papers, we will use this sample to derive the poor cluster x-ray luminosity function and gas mass function, and will examine the optical/x-ray properties of the clusters in more detail. (C) 1996 American Astronomical Society. C1 UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,GREENBELT,MD 20771. RP Ledlow, MJ (reprint author), NEW MEXICO STATE UNIV,DEPT ASTRON,BOX 30001 DEPT 4500,LAS CRUCES,NM 88003, USA. NR 35 TC 29 Z9 29 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1996 VL 112 IS 2 BP 388 EP 406 DI 10.1086/118023 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ553 UT WOS:A1996UZ55300006 ER PT J AU Holtzman, JA Watson, AM Mould, JR Gallagher, JS Ballester, GE Burrows, CJ Clarke, JT Crisp, D Evans, RW Griffiths, RE Hester, JJ Hoessel, JG Scowen, PA Stapelfeldt, KR Trauger, JT Westphal, JA AF Holtzman, JA Watson, AM Mould, JR Gallagher, JS Ballester, GE Burrows, CJ Clarke, JT Crisp, D Evans, RW Griffiths, RE Hester, JJ Hoessel, JG Scowen, PA Stapelfeldt, KR Trauger, JT Westphal, JA TI Star clusters in interacting and cooling flow galaxies SO ASTRONOMICAL JOURNAL LA English DT Article ID SPACE-TELESCOPE OBSERVATIONS; GALACTIC GLOBULAR-CLUSTERS; DISCOVERY; HALO AB Two interacting galaxies and four central galaxies in cooling flow clusters were observed with the Hubble Space Telescope to look for young compact massive star clusters. The two interacting galaxies, NGC 3597 and NGC 6052, show clear evidence for resolved bright blue clusters that are likely to be comparable in mass to Galactic globulars based on their colors and brightnesses. In NGC 3597, the clusters have physical sizes comparable to Galactic globulars. In NGC 6052, there are a few compact clusters, but most appear more extended. No such objects were seen in three of the four cooling flow galaxies. The central galaxy in Abell 1795 may have several massive blue clusters, but its distance prevents us from knowing how compact they are. (C) 1996 American Astronomical Society. C1 AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. ESA,DIV ASTROPHYS,DEPT SPACE SCI,BALTIMORE,MD 21218. JET PROP LAB,PASADENA,CA 91109. JOHNS HOPKINS UNIV,DEPT ASTRON,BALTIMORE,MD 21218. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP Holtzman, JA (reprint author), NEW MEXICO STATE UNIV,DEPT ASTRON,DEPT 4500,BOX 30001,LAS CRUCES,NM 88003, USA. RI Stapelfeldt, Karl/D-2721-2012; Clarke, John/C-8644-2013 NR 32 TC 67 Z9 67 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1996 VL 112 IS 2 BP 416 EP & DI 10.1086/118025 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ553 UT WOS:A1996UZ55300008 ER PT J AU ONeil, K Bothun, GD Smith, EP Stecher, TP AF ONeil, K Bothun, GD Smith, EP Stecher, TP TI Deep UV imaging of galaxies in the Fornax cluster SO ASTRONOMICAL JOURNAL LA English DT Article ID ULTRAVIOLET-TELESCOPE OBSERVATIONS; SURFACE BRIGHTNESS GALAXIES; DWARF ELLIPTICAL GALAXIES; VIRGO CLUSTER; CATALOG AB We compare the Astro-1 Ultraviolet Imaging Telescope (UIT) deep image of the Fornax cluster with deep optical surveys for purposes of determining the efficacy of vacuum ultraviolet imaging in terms of the recovery of very faint and/or diffuse galaxies. This field covers approximately 1/3 of a square degree and contains 15 galaxies with B-t brighter than 18.0 mag. A 1000 s near-UV image detected ten of these galaxies. These ten detections include three luminous ellipticals, two bonafide dwarf ellipticals, and five galaxies of small angular size that may or may not be members of the Fornax cluster. If these optically faint galaxies are members of the Fornax cluster, then the VUV imaging did sample an appreciable range in the galaxy luminosity function. For the dwarf ellipticals, a comparison of their optical and UV fluxes indicates the UV light is not dominated by any hot population but rather represents the general UV characteristics of the underlying stellar population. In particular, we can place an upper limit of 25 O3-5 stars that are present due to possible low level star formation. Furthermore, the UV-optical colors of the dEs are significantly redder than Galactic globular clusters which indicates that these dEs do not have a significant population of extreme horizontal branch stars. With the failure of the near-UV camera aboard the Astro-2 mission, the opportunity for performing a deeper near-UV survey has been lost. We conclude, however, that such a survey would have good sensitivity to the detection of optically faint and/or diffuse galaxies and would provide credible information on the galaxy luminosity function. (C) 1996 American Astronomical Society. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP ONeil, K (reprint author), UNIV OREGON,DEPT PHYS,EUGENE,OR 97403, USA. NR 22 TC 6 Z9 6 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1996 VL 112 IS 2 BP 431 EP 437 DI 10.1086/118026 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ553 UT WOS:A1996UZ55300009 ER PT J AU Watson, AM Gallagher, JS Holtzman, JA Hester, JJ Mould, JR Ballester, GE Burrows, CJ Casertano, S Clarke, JT Crisp, D Evans, R Griffiths, RE Hoessel, JG Scowen, PA Stapelfeldt, KR Trauger, JT Westphal, JA AF Watson, AM Gallagher, JS Holtzman, JA Hester, JJ Mould, JR Ballester, GE Burrows, CJ Casertano, S Clarke, JT Crisp, D Evans, R Griffiths, RE Hoessel, JG Scowen, PA Stapelfeldt, KR Trauger, JT Westphal, JA TI The discovery of young, luminous, compact stellar clusters in the starburst galaxy NGC 253 SO ASTRONOMICAL JOURNAL LA English DT Article ID SPACE-TELESCOPE OBSERVATIONS; MERGER REMNANT NGC-7252; SUPER-STAR-CLUSTERS; GLOBULAR-CLUSTERS; NGC-253; M82; POPULATION; NGC-1705; SPECTRA; SCALE AB We report the discovery of four young, luminous, compact stellar clusters in the central region of the starburst spiral galaxy NGC 253. One cluster has an intrinsic M(v) of about -15 or brighter, an inferred mass in excess of 1.5x10(6) M(.), assuming a Salpeter IMF from 0.08M(.) to 100M(.), and is resolved with a half-light radius of about 2.5 parsec if it has a radial profile similar to a Galactic globular cluster. The others have intrinsic M(v) of about -11 or brighter, inferred masses in excess of 5x10(4) M(.), and are similarly compact. These clusters are excellent candidate young globular clusters. The brighter cluster is similar in luminosity, inferred mass, and compactness to the super star clusters found in other sites of ongoing or recent intense star formation. The location of these clusters in the midst of a starburst region suggests that intense star formation may be a key ingredient in their creation. There are hints that these candidate young globular clusters may be forming with a high specific frequency. (C) 1996 American Astronomical Society. C1 NEW MEXICO STATE UNIV,DEPT ASTRON,LAS CRUCES,NM 88003. AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. SPACE TELESCOPE SCI INST,ESA,DEPT SPACE SCI,DIV ASTROPHYS,BALTIMORE,MD 21218. CALTECH,JET PROP LAB,PASADENA,CA 91109. JOHNS HOPKINS UNIV,DEPT ASTRON,BALTIMORE,MD 21218. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP Watson, AM (reprint author), LOWELL OBSERV,1400 W MARS HILL RD,FLAGSTAFF,AZ 86001, USA. RI Stapelfeldt, Karl/D-2721-2012; Clarke, John/C-8644-2013 NR 54 TC 85 Z9 86 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1996 VL 112 IS 2 BP 534 EP & DI 10.1086/118032 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ553 UT WOS:A1996UZ55300015 ER PT J AU Hill, RS Cheng, KP Smith, EP Hintzen, PMN Bohlin, RC OConnell, RW Roberts, MS Smith, AM Stecher, TP AF Hill, RS Cheng, KP Smith, EP Hintzen, PMN Bohlin, RC OConnell, RW Roberts, MS Smith, AM Stecher, TP TI UIT: New ultraviolet stellar photometry and surface brightness profiles of the globular cluster M79 (NGC 1904) SO ASTRONOMICAL JOURNAL LA English DT Article ID IMAGING TELESCOPE; HORIZONTAL-BRANCH; LUMINOSITY FUNCTIONS; CCD PHOTOMETRY; STARS; NGC-1904; POPULATIONS; SPECTROSCOPY; MODELS; IMAGES AB Ultraviolet photometry is presented for the globular cluster M79 (NGC 1904) according to the final calibration of the images obtained on the Astro-1 Spacelab mission by the Ultraviolet Imaging Telescope. These results include both point-source and surface photometry at 152 nm and 249 nm. An ultraviolet color-magnitude (C-M) diagram in these bandpasses is presented. The detected stars are also cross-matched with the ground-based photometry of Ferraro et al. to produce C-M and two-color diagrams covering a 4000 Angstrom span in wavelength. The observed horizontal branch (HE) is compared with stellar interior models of the zero-age HE (ZAHB). Many stars are found in post-HE evolutionary stages more luminous than the ZAHB. The distribution of stars along the ZAHB in m(152)-m(249) color is investigated, and an indication of possible bimodality is found. The relative population of the blue HE tail may vary with radius for radii greater than 1'. Ultraviolet surface brightness and color-index profiles are presented. The previously reported central gradient in the m(152)-V color index is confirmed, and a faint diffuse component is detected outside a radius of 40('') in the 152 nm band. Two possible causes of the central color gradient are discussed: mass segregation, and the destruction of red giant envelopes by enhanced mass loss in the cluster core. (C) 1996 American Astronomical Society. C1 CALIF STATE UNIV FULLERTON, DEPT PHYS, FULLERTON, CA 92634 USA. NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. UNIV NEVADA, DEPT PHYS & ASTRON, LAS VEGAS, NV 89154 USA. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. UNIV VIRGINIA, CHARLOTTESVILLE, VA 22903 USA. NATL RADIO ASTRON OBSERV, CHARLOTTESVILLE, VA 22903 USA. RP Hill, RS (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HUGHES STX CORP, CODE 681, GREENBELT, MD 20071 USA. NR 50 TC 11 Z9 11 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1996 VL 112 IS 2 BP 601 EP 617 DI 10.1086/118037 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ553 UT WOS:A1996UZ55300020 ER PT J AU Schaerer, D deKoter, A Schmutz, W Maeder, A AF Schaerer, D deKoter, A Schmutz, W Maeder, A TI Combined stellar structure and atmosphere models for massive stars .2. Spectral evolution on the main sequence SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars, atmospheres; early-type; evolution; fundamental parameters; Hertzsprung-Russel (HR) diagram; massloss ID HOT LUMINOUS STARS; INCLUDING SPHERICAL EXTENSION; RADIATION-DRIVEN WINDS; O-TYPE STARS; B-SUPERGIANTS; QUANTITATIVE SPECTROSCOPY; TERMINAL VELOCITIES; H-ALPHA; X-RAYS; ULTRAVIOLET AB In Schaerer et al. (1995, Paper I) we have presented the first ''combined stellar structure and atmosphere models'' (CoStar) for massive stars, which consistently treat the entire mass loosing star from the center out to the outer region of the stellar wind. The models use up-to-date input physics and state-of-the-art techniques to model both the stellar interior and the spherically expanding non-LTE atmosphere. The atmosphere models include line blanketing for all elements from hydrogen to zinc. The present publication covers the spectral evolution corresponding to the main sequence interior evolution discussed in Paper I. The CoStar results presented in this paper comprise: (a) flux distributions, from the EUV to the far IR, and the ionizing fluxes in the hydrogen and helium continua, (b) absolute optical and infrared UBVRIJHKLMN photometric magnitudes and UV colors, (c) detailed line blanketed UV spectra, and (d) non-LTE hydrogen and helium line spectra in the optical and IR, including theoretical K band spectra. These results may, e.g., be used for population synthesis models intended to study the massive star content in young starforming regions. We compare our results with other predictions from LTE and non-LTE plane parallel models and point out the improvements and the importance of using adequate atmosphere models including stellar winds for massive stars. Particular emphasis is given to comparisons of the UV spectral evolution with observations, including continuum indices and several metal line signatures of P-Cygni lines and broad absorption features. Good agreement is found for most UV features. In particular, we are able to reproduce the strong observed Fe III 1920 Angstrom feature in late O and early B giants and supergiants. This feature is found to depend sensitively on temperature and may be used to derive effective temperatures for these stars. We also derive a simple formula to determine mass loss rates from the equivalent width of hydrogen recombination lines (Her, P alpha and B alpha) for OB stars showing net emission in one or more of these lines. C1 NASA, GODDARD SPACE FLIGHT CTR, USRA, GREENBELT, MD 20771 USA. ETH ZENTRUM, INST ASTRON, CH-8092 ZURICH, SWITZERLAND. RP Schaerer, D (reprint author), OBSERV GENEVA, CH-1290 SAUVERNY, SWITZERLAND. RI Schmutz, Werner/B-4153-2014 OI Schmutz, Werner/0000-0003-1159-5639 NR 70 TC 45 Z9 46 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 AUG PY 1996 VL 312 IS 2 BP 475 EP 495 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VC333 UT WOS:A1996VC33300017 ER PT J AU Reynolds, AP Parmar, AN Stollberg, MT Verbunt, F Roche, P Wilson, RB Finger, MH AF Reynolds, AP Parmar, AN Stollberg, MT Verbunt, F Roche, P Wilson, RB Finger, MH TI Accretion torques in the transient X-ray pulsar EXO 2030+375 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars, individual, EXO 2030+375; stars, neutron; stars, pulsars, general; stars, emission-line, Be; X-rays, stars; accretion disks ID LUMINOSITY DEPENDENCE; NEUTRON STARS; EXO-2030+375; DISCOVERY AB In 1985 May - October, EXOSAT observed two outbursts from the previously unknown accreting X-ray pulsar EXO 2030+375. Using the orbital solution derived by the BATSE experiment on CGRO, the behavior of the pulse period variations can now be studied with much less ambiguity than was possible based on the EXOSAT observations alone. There is little evidence for spin-down at low luminosity during the first outburst. Three different accretion torque models are applied to the intrinsic pulse-period data, but none give formally acceptable its. However models for the pulse period variations which allow the possibility of spin-down (magnetically-threaded disk models) provide a better description of the observed variations than the simplest accretion torque model. We confirm that the dependence of pulse period with observed X-ray luminosity is significantly steeper than that predicted by simple accretion torque theory, with -P-pulse proportional to L(X)(1.2) rather than -P-pulse proportional to L(X)(6/7) as expected. Distance estimates using the Wang and Ghosh & Lamb models range from 4.2-5.2 kpc respectively, while the magnetic dipole moment is 10-11 10(30) G cm(3). The distance is consistent with that derived from photometric studies of the companion star, and the magnetic moment is consistent with both the luminosity at which centrifugal inhibition of accretion would terminate the outburst, and the non-detection of a cyclotron feature in the X-ray spectrum. C1 EUROPEAN SPACE AGCY, DEPT SPACE SCI, DIV ASTROPHYS, NL-2200 AG NOORDWIJK, NETHERLANDS. UNIV ALABAMA, DEPT PHYS, HUNTSVILLE, AL 35809 USA. UNIV SUSSEX, MAPS, CTR ASTRON, BRIGHTON BN1 9QH, E SUSSEX, ENGLAND. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, HUNTSVILLE, AL 35812 USA. RP STERREKUNDIG INST, POB 80 000, NL-3508 TA UTRECHT, NETHERLANDS. NR 22 TC 19 Z9 19 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD AUG PY 1996 VL 312 IS 3 BP 872 EP 878 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VE344 UT WOS:A1996VE34400021 ER PT J AU Aversa, F Barbiellini, G Basini, G Bellotti, R Bidoli, V Bocciolini, M Bravar, U Boezio, M Cafagna, F Candusso, M Casolino, M Castellano, M Circella, M Colavita, A DeCataldo, G DeMarzo, C DePascale, MP Finetti, N Fratnik, F Giglietto, N Golden, RL Grimani, C Hof, M Marangelli, B Brancaccio, FM Menn, W Mitchell, JW Morselli, A Papini, P Perego, A Piccardi, S Picozza, P Raino, A Ricci, M Schiavon, P Simon, M Sparvoli, R Spillantini, P Spinelli, P Stephens, SA Stochaj, SJ Streitmatter, RE Vacchi, A Zampa, N AF Aversa, F Barbiellini, G Basini, G Bellotti, R Bidoli, V Bocciolini, M Bravar, U Boezio, M Cafagna, F Candusso, M Casolino, M Castellano, M Circella, M Colavita, A DeCataldo, G DeMarzo, C DePascale, MP Finetti, N Fratnik, F Giglietto, N Golden, RL Grimani, C Hof, M Marangelli, B Brancaccio, FM Menn, W Mitchell, JW Morselli, A Papini, P Perego, A Piccardi, S Picozza, P Raino, A Ricci, M Schiavon, P Simon, M Sparvoli, R Spillantini, P Spinelli, P Stephens, SA Stochaj, SJ Streitmatter, RE Vacchi, A Zampa, N TI Identification of cosmic ray electrons and positrons by neural networks SO ASTROPARTICLE PHYSICS LA English DT Article ID TRANSITION RADIATION DETECTOR; PERFORMANCE AB A data analysis based on artificial neural network classifiers has been done to identify cosmic ray electrons and positrons detected with the balloon-borne NMSU/Wizard-TS93 experiment. The information is provided by two ancillary and independent particle detectors: a transition radiation detector and a silicon-tungsten imaging calorimeter, Electrons and positrons measured during the flight have been identified with background rejection factors of 80 +/- 3 and 500 +/- 37 at signal efficiencies of 72 +/- 3% and 86 +/- 2% for the transition radiation detector and silicon-tungsten imaging calorimeter, respectively, The ability of the artificial neural network classifiers to perform a careful multidimensional analysis surpasses the results achieved by conventional methods. C1 IST NAZL FIS NUCL,I-70126 BARI,ITALY. UNIV ROMA TOR VERGATA,I-00133 ROME,ITALY. IST NAZL FIS NUCL,I-00133 ROME,ITALY. UNIV TRIESTE,I-34147 TRIESTE,ITALY. IST NAZL FIS NUCL,I-34147 TRIESTE,ITALY. UNIV FLORENCE,I-50125 FLORENCE,ITALY. IST NAZL FIS NUCL,I-50125 FLORENCE,ITALY. IST NAZL FIS NUCL,LAB NAZL FRASCATI,I-00044 FRASCATI,ITALY. UNIV PERUGIA,I-06100 PERUGIA,ITALY. IST NAZL FIS NUCL,I-06100 PERUGIA,ITALY. NEW MEXICO STATE UNIV,LAS CRUCES,NM 88003. TATA INST FUNDAMENTAL RES,BOMBAY 400005,MAHARASHTRA,INDIA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV SIEGEN,SIEGEN,GERMANY. RI Morselli, Aldo/G-6769-2011; giglietto, nicola/I-8951-2012; Castellano, Marcello/J-3428-2012; Cafagna, Francesco/A-9299-2010; Vacchi, Andrea/C-1291-2010; OI Morselli, Aldo/0000-0002-7704-9553; giglietto, nicola/0000-0002-9021-2888; Castellano, Marcello/0000-0002-4211-2903; Cafagna, Francesco/0000-0002-7450-4784; Vacchi, Andrea/0000-0003-3855-5856; Bellotti, Roberto/0000-0003-3198-2708; casolino, marco/0000-0001-6067-5104; Sparvoli, Roberta/0000-0002-6314-6117; Picozza, Piergiorgio/0000-0002-7986-3321; Papini, Paolo/0000-0003-4718-2895; Boezio, Mirko/0000-0002-8015-2981 NR 26 TC 5 Z9 5 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 AUG PY 1996 VL 5 IS 2 BP 111 EP 117 DI 10.1016/0927-6505(96)00009-6 PG 7 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA VE116 UT WOS:A1996VE11600002 ER PT J AU Mushotzky, R Loewenstein, M Arnaud, KA Tamura, T Fukazawa, Y Matsushita, K Kikuchi, K Hatsukade, I AF Mushotzky, R Loewenstein, M Arnaud, KA Tamura, T Fukazawa, Y Matsushita, K Kikuchi, K Hatsukade, I TI Measurement of the elemental abundances in four rich clusters of galaxies .1. Observations SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, abundances; galaxies, clusters, individual (Abell 496, Abell 1060, Abell 2199, AWM 7); X-rays, galaxies ID SOLID-STATE SPECTROMETER; X-RAY-SPECTRA; ELLIPTIC GALAXIES; CHEMICAL EVOLUTION; MAGELLANIC CLOUDS; ASCA OBSERVATIONS; HOT PLASMA; IRON; TEMPERATURE; METALLICITY AB The elemental abundances of O, Ne, Mg, Si, S, Ca, Ar, and Fe for four clusters of galaxies (Abell 496, 1060, 2199, and AWM 7) are determined from X-ray spectra derived from Advanced Satellite for Cosmology and Astrophysics performance verification phase observations. Since the gas in the outer parts of the cluster is optically thin and virtually isothermal, the abundance analysis is very straightforward compared to the analysis of stellar or H II region spectra. We find that the abundance ratios of all four clusters are very similar. The mean abundances of O, Ne, Si, S, and Fe are 0.48, 0.62, 0.65, 0.25, and 0.32, respectively, relative to solar. The abundances of Si, S, and Fe are unaffected by the uncertainties in the atomic physics of the Fe L shell. The abundances of Ne and Mg and to a lesser extent O are affected by the present uncertainties in Fe L physics and are thus somewhat more uncertain. The Fe abundances derived from the Fe L lines agree well with those derived from the Fe K lines for these clusters. The observed ratio of the relative abundance of elements is consistent with an origin of all the metals in Type II supernovae. The presence of large numbers of Type II supernovae during the early stages of evolution of cluster galaxies is a very strong constraint on all models of galaxy and chemical evolution and implies either a very flat initial mass function or bimodal star formation during the period when most of the metals were created. C1 UNIV TOKYO,DEPT PHYS,BUNKYO KU,TOKYO 113,JAPAN. TOKYO METROPOLITAN UNIV,DEPT PHYS,HACHIOJI,TOKYO 19202,JAPAN. MIYAZAKI UNIV,FAC ENGN,MIYAZAKI 88912,JAPAN. UNIV SPACE RES ASSOC,WASHINGTON,DC. UNIV MARYLAND,COLLEGE PK,MD 20742. RP Mushotzky, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 666,GREENBELT,MD 20771, USA. RI Kikuchi, Kenichi/H-3382-2011; Tamura, Takayuki/K-8236-2012 OI Kikuchi, Kenichi/0000-0002-2088-0717; NR 58 TC 169 Z9 169 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 686 EP 694 DI 10.1086/177541 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600007 ER PT J AU Loewenstein, M Mushotzky, RF AF Loewenstein, M Mushotzky, RF TI Measurement of the elemental abundances in four rich clusters of galaxies .2. The initial mass function and mass loss in elliptical galaxies, enrichment and energetics in the ICM SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, abundances; galaxies, elliptical and lenticular, cD; galaxies, luminosity function, mass function; intergalactic medium ID INTRACLUSTER MEDIUM; EVOLUTION; IRON; GAS; SUPERNOVAE AB We compare observations from the Advanced Satellite fop Cosmology and Astrophysics of abundances in the intracluster media in four clusters, as reported by Mushotzky and coworkers, with calculations of enrichment by protogalactic supernova-driven winds in a simple stellar population with a power-law initial, mass function. Using the most recently calculated yields from Type II supernovae, we find that we can account for the total observed amounts of iron, oxygen, and silicon if the initial mass function is significantly flatter than the Salpeter function. Some discrepancies with other elements are indicated. Model-independent implications for the origin and heating of the intracluster medium and for the energetics of protoelliptical galaxies are discussed. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. RP Loewenstein, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 662,GREENBELT,MD 20771, USA. NR 39 TC 103 Z9 103 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 695 EP 703 DI 10.1086/177542 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600008 ER PT J AU Gerber, RA AF Gerber, RA TI Global effects of softening n-body galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, kinematics and dynamics; galaxies, structure; methods, numerical AB Softening of the gravitational potential in n-body simulations, introduced as a modification to Newtonian gravity on the small scale, can affect the large-scale, global dynamics of computer models of galaxies. These effects arise because softening modifies the gravitational binding energy and changes the equilibrium configuration of self-gravitating systems. In this paper we give the analytic expressions for the ''softened'' gravitational potential energy of some example systems. We then present a corrected form of the scalar virial theorem, which describes the relationship between potential and kinetic energies in equilibrium galaxies. It is important to understand these phenomena when conducting numerical experiments on galaxies. It is often desired to numerically construct and study an equilibrium galaxy derived from an analytic model. We show by example that the use of softening can lead to global phenomena that cannot be discussed solely in terms of Newtonian gravity. As an example, we examine numerically the behavior of a spherical galaxy undergoing fundamental mode oscillations as the softening length is varied. RP Gerber, RA (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MS-245-3,MOFFETT FIELD,CA 94035, USA. NR 12 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 724 EP 731 DI 10.1086/177545 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600011 ER PT J AU Gallagher, JS Mould, JR DeFeijter, E Holtzman, J Stappers, B Watson, A Trauger, J Ballester, GE Burrows, CJ Casertano, S Clarke, JT Crisp, D Griffiths, RE Hester, JJ Hoessel, J Krist, J Matthews, LD Scowen, PA Stapelfeld, KR Westphal, JA AF Gallagher, JS Mould, JR DeFeijter, E Holtzman, J Stappers, B Watson, A Trauger, J Ballester, GE Burrows, CJ Casertano, S Clarke, JT Crisp, D Griffiths, RE Hester, JJ Hoessel, J Krist, J Matthews, LD Scowen, PA Stapelfeld, KR Westphal, JA TI Main-sequence stars and the star formation history of the outer disk in the large magellanic cloud SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, photometry; galaxies, stellar content; Hertzsprung-Russell diagram; Magellanic Clouds; stars, evolution ID COLOR-MAGNITUDE DIAGRAMS; GLOBULAR-CLUSTERS; FAINT STAR; LUMINOSITY FUNCTIONS; LMC CLUSTERS; FIELD STARS; GALAXIES; AGE; POPULATION; EVOLUTION AB Using the Wide Field Planetary Camera 2 on the Hubble Space Telescope, we have obtained a deep color-magnitude diagram in V- and I-band equivalents for more than 2000 stars in a patch of the outer disk of the Large Magellanic Cloud (LMC). Aperture photometry is feasible from these data with good signal-to-noise ratio for stars with V less than or equal to 25, which allows us for the first time to construct a color-magnitude diagram for LMC disk stars on the lower main sequence, extending beyond the oldest main-sequence turnoff point. We analyze the structure of the main-sequence band and overall morphology of the color-magnitude diagram to obtain a star formation history for the region. A comparison between the distribution of stars across the main-sequence band for M(V) less than or equal to 4 and a stellar population model constrains historical star formation rates within the past 3 Gyr. The stellar populations in this region sample the outer LMC disk for stars with ages of 1 Gyr or older that have had time to spatially mix. The structure of the main-sequence band requires that star formation occurred at a roughly constant rate during most of the past approximate to 3 Gyr. However, the distribution of subgiant stars indicate that a pronounced peak in the star formation rate likely occurred about 2 Gyr ago, prior to which the star formation rate had not been enhanced for several Gyr. Studies over timescales of more than 3 Gyr require a separation of the effects of star formation history and the chemical evolution on the LMC color-magnitude diagrams, which is difficult to achieve without additional constraints. If lower main-sequence stars in the LMC have moderate metallicities, then the age for most LMC disk stars is less than about 8 Gyr. C1 AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. LOWELL OBSERV,FLAGSTAFF,AZ 86001. NEW MEXICO STATE UNIV,DEPT ASTRON,LAS CRUCES,NM 88003. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV MICHIGAN,DEPT ATMOSPHER & OCEAN SCI,ANN ARBOR,MI 48109. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. UNIV UTRECHT,UTRECHT,NETHERLANDS. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. SUNY STONY BROOK,DEPT EARTH & SPACE SCI,ASTRON PROGRAM,STONY BROOK,NY 11794. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP Gallagher, JS (reprint author), UNIV WISCONSIN,DEPT ASTRON,5534 STERLING,475 N CHARTER ST,MADISON,WI 53706, USA. RI Clarke, John/C-8644-2013 NR 62 TC 71 Z9 71 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 732 EP 741 DI 10.1086/177546 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600012 ER PT J AU Jones, DH Mould, JR Watson, AM Grillmair, C Gallagher, JS Ballester, GE Burrows, CJ Casertano, S Clarke, JT Crisp, D Griffiths, RE Hester, JJ Hoessel, JG Holtzman, JA Scowen, PA Stapelfeldt, KR Trauger, JT Westphal, JA AF Jones, DH Mould, JR Watson, AM Grillmair, C Gallagher, JS Ballester, GE Burrows, CJ Casertano, S Clarke, JT Crisp, D Griffiths, RE Hester, JJ Hoessel, JG Holtzman, JA Scowen, PA Stapelfeldt, KR Trauger, JT Westphal, JA TI Visible and far-ultraviolet WFPC2 imaging of the nucleus of the galaxy NGC 205 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, individual (NGC 205); galaxies, nuclei; galaxies, stellar content ultraviolet, stars ID DWARF ELLIPTICAL GALAXIES; PLANETARY CAMERA OBSERVATIONS; STELLAR POPULATIONS; VIRGO CLUSTER; NGC-205; M31; PERFORMANCE; EXTINCTION; CATALOG; SYSTEMS AB We have imaged the nucleus of NGC 205 through the F555W and F160BW filters of WFPC2 on the high-resolution planetary camera (PC). The nucleus consists of a resolved cluster of stars extending 7 '' x 6 ''. The projected radial distribution of surface brightness can be fitted by a Hubble law with a small core of FWHM 214 x 190 mas (0.74 x 0.66 pc). We find that the nucleus of NGC 205 shares a number of characteristics with globular clusters. Absolute photometry is also presented in a half-arcsec aperture and is found to verify the amount of UV upturn observed in the spectral energy distribution of the nucleus by others (e.g., Bertola et al. 1995). Of the hypotheses available to explain the origin of the nucleus, the observations are most consistent with its being an intermediate age cluster. The most likely scenarios are that it is a either a star cluster whose orbit has decayed-therefore drawing it to rest at the galaxy center-or a cluster that has formed as the repository of the gas from generations of star formation. Together with the ground-based measurement of a low-velocity dispersion, the small core radius implies a 10(7) yr relaxation time, suggesting the cluster core may have collapsed. An upper limit of 9 x 10(4) M. can be put on the mass of any central black hole. C1 NEW MEXICO STATE UNIV,DEPT ASTRON,LAS CRUCES,NM 88003. JET PROPULS LAB,PASADENA,CA 91109. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV MICHIGAN,DEPT ATMOSPHER & OCEAN SCI,ANN ARBOR,MI 48109. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. JOHNS HOPKINS UNIV,DEPT ASTRON,BALTIMORE,MD 21218. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP Jones, DH (reprint author), AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,INST ADV STUDIES,WESTON CREEK PO,WESTON,ACT 2611,AUSTRALIA. RI Stapelfeldt, Karl/D-2721-2012 NR 40 TC 35 Z9 35 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 742 EP 749 DI 10.1086/177547 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600013 ER PT J AU Tegmark, M Hartmann, DH Briggs, MS Hakkila, J Meegan, CA AF Tegmark, M Hartmann, DH Briggs, MS Hakkila, J Meegan, CA TI Improved limits on gamma-ray burst repetition from BATSE SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, bursts; methods, statistical ID CATALOG; TIME; VELOCITIES; NETWORK; MODELS; BIRTH; STARS AB We tighten previous upper limits on gamma-ray burst repetition by analyzing the angular power spectrum of the BATSE 3B catalog of 1122 bursts. At 95% confidence, we find that no more than 2% of all observed bursts can be labeled as repeaters, even if no sources are observed to repeat more than once. If a fraction f of all observed bursts can be labeled as repeaters that are observed to burst nu times each, then all models with (nu - 1)f greater than or equal to 0.05 are ruled out at 99% confidence, as compared to the best previous 99% limit (nu - 1)f greater than or equal to 0.27. At 95% confidence, our new limit is (nu - 1)f greater than or equal to 0.02. Thus, even a cluster of six events from a single source would have caused excess power above that present in the 3B catalog. We conclude that the current BATSE data are consistent with no repetition of classical gamma-ray bursts and that any repeater model is severely constrained by the near-perfect isotropy of their angular distribution. C1 CLEMSON UNIV,DEPT PHYS & ASTRON,CLEMSON,SC 29634. UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. MANKATO STATE UNIV,DEPT PHYS & ASTRON,MANKATO,MN 56002. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP Tegmark, M (reprint author), MAX PLANCK INST PHYS & ASTROPHYS,FOHRINGER RING 6,D-80805 MUNICH,GERMANY. NR 63 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 757 EP 763 DI 10.1086/177549 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600015 ER PT J AU Gotthelf, EV Hamilton, TT Helfand, DJ AF Gotthelf, EV Hamilton, TT Helfand, DJ TI The Einstein Observatory detection of faint x-ray flashes SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, bursts; surveys; X-rays, bursts ID BURSTS; TRANSIENTS; EMISSION; ORBIT AB We report on the result of an extensive search for X-ray counterparts to gamma-ray bursts (GRBs) using data acquired with the imaging proportional counter (IPC) on board the Einstein Observatory. We examine background sky fields from all pointed observations for short timescale (less than or similar to 10 s), transient X-ray phenomena not associated a priori with detectable point sources. A total of 1.5 x 10(7) s of exposure time was searched on arcminute spatial scales down to a limiting sensitivity of 10(-11) ergs cm(-2) s(-1) in the 0.2-3.5 keV IPC band. Forty-two highly significant X-ray flashes (Poisson probability less than 10(-7) of being produced by statistical fluctuations) are discovered, of which 18 have spectra consistent with an extragalactic origin and light curves similar to the Ginga-detected X-ray counterparts to GRBs. Great care is taken to identify and exclude instrumental and observational artifacts; we develop a set of tests to cull events that may be associated with spacecraft or near-Earth space backgrounds. The flashes are found to be distributed isotropically on the sky and have an approximately Euclidean number-size relation. They are not associated with any known sources, and, in particular, they do not correlate with the nearby galaxy distribution. Whether or not these flashes are astrophysical and/or associated with GRBs, the limits imposed by the search described herein produces important constraints on GRB models. In this paper, we discuss possible origins for these flashes; in a companion paper, we use the results of our search to constrain strongly all halo models for GRBs. C1 CALTECH,DEPT ASTRON,PASADENA,CA 91125. COLUMBIA UNIV,DEPT ASTRON,NEW YORK,NY 10027. COLUMBIA UNIV,COLUMBIA ASTROPHYS LAB,NEW YORK,NY 10027. UNIV SPACE RES ASSOC,WASHINGTON,DC. RP Gotthelf, EV (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 30 TC 15 Z9 15 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 779 EP 794 DI 10.1086/177552 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600018 ER PT J AU Hamilton, TT Gotthelf, EV Helfand, DJ AF Hamilton, TT Gotthelf, EV Helfand, DJ TI The absence of X-ray flashes from nearby galaxies and the gamma-ray burst distance scale SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, bursts; surveys; X-rays, bursts ID MASS; UNIVERSE; HALO AB If typical gamma-ray bursts (GRBs) have X-ray counterparts similar to those detected by Ginga, then sensitive-focusing X-ray telescopes will be able to detect GRBs 3 orders of magnitude fainter than the detection limit of the Burst and Transient Source Experiment (BATSE). If a substantial portion of the burst population detected by BATSE originates in a Galactic halo at distances greater than or equal to 150 kpc, existing X-ray telescopes will be able to detect GRBs in external galaxies out to a distance of at least 4.5 Mpc. As reported in Gotthelf, Hamilton, & Helfand, the imaging proportional counter (IPC) on board the Einstein Observatory detected 42 transient events with pointlike spatial characteristics and timescales of less than 10 s. These events are distributed isotropically on the sky; in particular, they are not concentrated in the directions of nearby external galaxies. For halo models of the BATSE bursts with radii of 150 kpc or greater, we would expect to see several burst events in observations pointed toward nearby galaxies. We see none. We therefore conclude that if the Ginga detections are representative of the population of GRBs sampled by BATSE, GRBs cannot originate in a Galactic halo population with limiting radii between 150 and 400 kpc. Inasmuch as halos with limiting radii outside of this range have been excluded by the BATSE isotropy measurements, our result indicates that all halo models are excluded. This result is independent of whether the flashes we do detect have an astronomical origin. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. COLUMBIA UNIV,DEPT ASTRON,NEW YORK,NY 10027. COLUMBIA UNIV,COLUMBIA ASTROPHYS LAB,NEW YORK,NY 10027. UNIV SPACE RES ASSOC,WASHINGTON,DC. RP Hamilton, TT (reprint author), CALTECH,DEPT ASTRON,PASADENA,CA 91125, USA. NR 24 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 795 EP 801 DI 10.1086/177553 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600019 ER PT J AU Borkowski, KJ Szymkowiak, AE Blondin, JM Sarazin, CL AF Borkowski, KJ Szymkowiak, AE Blondin, JM Sarazin, CL TI A circumstellar shell model for the Cassiopeia A supernova remnant SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; hydrodynamics; ISM, individual (Cassiopeia A); supernova remnants ID SELF-SIMILAR SOLUTIONS; X-RAY-SPECTRUM; NOVA REMNANT; EMISSION; EJECTA; ABUNDANCES; VELOCITY; MASS AB We model the Cassiopeia A supernova remnant in the framework of the circumstellar medium (CSM) interaction picture. In this model, the slow red supergiant wind of the supernova (SN) progenitor was swept into a dense shell by a fast stellar wind in the subsequent blue supergiant stage of the progenitor star. The supernova blast wave propagated quickly (less than or equal to 100 yr) through the tenuous wind-blown bubble located within this shell and then slowed down in the dense (n(H) similar to 15 cm(-3)) CSM shell. The shell was impulsively accelerated during this interaction stage; during the subsequent interaction with SN ejecta, the shell has been further accelerated to similar to 2000 km s(-1), the currently observed expansion rate. The comparison of our X-ray emission calculations with the ASCA spectrum suggests that about 8 M. of X-ray-emitting material is present in Cas A. Most of this mass is located in the CSM shell and in the outlying red supergiant wind. The X-ray continuum and the Fe K alpha line are dominated by the shell emission, but prominent K alpha complexes of Mg, Si, and S must be produced by SN ejecta with strongly enhanced abundances of these elements. Our hydrodynamical models indicate that about 2 M. of ejecta have been shocked. An explosion of a stellar He core is consistent with these findings. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. RP Borkowski, KJ (reprint author), N CAROLINA STATE UNIV,DEPT PHYS,RALEIGH,NC 27695, USA. NR 31 TC 57 Z9 57 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 866 EP 870 DI 10.1086/177560 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600026 ER PT J AU Long, KS Blair, WP Hubeny, I Raymond, JC AF Long, KS Blair, WP Hubeny, I Raymond, JC TI Observations of the dwarf nova VW Hydri in quiescence with the Hopkins Ultraviolet Telescope SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries, close; novae; cataclysmic variables; stars, individual (VW Hydri); ultraviolet, stars ID HUBBLE-SPACE-TELESCOPE; X-RAY-EMISSION; WHITE-DWARF; CATACLYSMIC VARIABLES; U-GEMINORUM; ACCRETION DISKS; RESOLUTION SPECTROSCOPY; BOUNDARY-LAYER; OUTBURSTS; PERFORMANCE AB The dwarf nova VW Hydri was in quiescence when it was observed in 1995 March with the Hopkins Ultraviolet Telescope on the Astro-2 space shuttle mission. The far-UV (820-1840 Angstrom) spectra are punctuated by broad Ly alpha and Ly beta absorption profiles and narrow absorption lines which can be identified with transitions expected in the atmosphere of a moderate-temperature white dwarf. There is no detectable emission shortward of 980 Angstrom. The only emission line seen is C IV lambda lambda 1548, 1551. If the emission from VW Hyi is due to a uniform-temperature white dwarf, then our spectra suggest that the temperature of the white dwarf was similar to 17,000 K at the time of our observations and that abundances in the atmosphere were subsolar. Improved fits to the data are obtained using models in which the far-UV emission arises in part from a white dwarf with near-solar abundances and in part from the accretion disk. However, given the uncertainties in model spectra of metal-enriched atmospheres in this temperature range and our limited knowledge of quiescent accretion disks, higher S/N spectra are needed to unambiguously assess the disk contribution to the far-UV spectrum of VW Hyi in quiescence. C1 JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP Long, KS (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. NR 38 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 964 EP 972 DI 10.1086/177567 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600033 ER PT J AU Kallman, TR Mukai, K Schlegel, EM Paerels, FB AF Kallman, TR Mukai, K Schlegel, EM Paerels, FB TI ASCA observations of the magnetic cataclysmic variable BY Camelopardalis SO ASTROPHYSICAL JOURNAL LA English DT Article DE novae; cataclysmic variables; stars, individual (BY Camelopardalis); X-rays, stars ID X-RAY-SPECTRUM; AM HERCULIS; ACCRETION; H0538+608; CATALOG; ROSAT; LINE AB We report on ASCA observations of the cataclysmic variable BY Cam. The unexcelled energy resolution of ASCA in the vicinity of the iron K line allows the line strength and energy to be constrained more tightly than has previously been possible. We show that the iron line consists of three components, consistent with highly ionized, nearly neutral and intermediate ionization components. We discuss the likely origins for each of these. We show that the neutral component is consistent with the expected flux from reprocessing in the white dwarf photosphere, and also that it is consistent with the limits on a soft blackbody continuum component from the white dwarf. The high-energy component is consistent with emission from the accretion shock, and it provides evidence for a high (similar or equal to 30 keV) temperature for the shock. The intermediate ionization component may originate in the accretion column, with the ionization being primarily due to photoionization from the emission at the shock. We also test for modulation of the various continuum and line components at the orbital period. C1 UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. RP Kallman, TR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 665,GREENBELT,MD 20771, USA. NR 23 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 973 EP 978 DI 10.1086/177568 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600034 ER PT J AU Kucera, TA Love, PJ Dennis, BR Holman, GD Schwartz, RA Zarro, DM AF Kucera, TA Love, PJ Dennis, BR Holman, GD Schwartz, RA Zarro, DM TI Study of the thermal/nonthermal electric field model in solar flares using spectral and spatial X-ray data from the Compton gamma ray observatory and Yohkoh SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun, corona; Sun, flares; Sun, X-rays, gamma rays ID THERMAL NONTHERMAL MODEL; RUNAWAY ELECTRONS; A MISSION; ACCELERATION; BURSTS; MICROWAVE; EMISSION; TELESCOPE; BATSE AB We have analyzed a solar flare in terms of a model in which electric fields produce both thermal emission from Joule-heated electrons and nonthermal emission from runaway electrons. The flare was observed by the Compton Gamma. Ray Observatory Burst and Transient Source Experiment (BATSE), the Yohkoh satellite, and GOES. The measured BATSE hard X-ray spectra were fitted with functions derived from the electric field model, thus allowing values for the temperature [(4-5) X 10(7) K] and emission measure [(1 X 10(46))-(2 X 10(47)) cm(-3)] of the thermal source to be determined. These are qualitatively consistent with the characteristics of the loop-top emission observed with the Yohkoh Hard X-ray Telescope. Furthermore, the hard X-ray footpoint emission observed by Yohkoh had flatter spectra than the loop-top emission, as predicted by the model. We found that the effects of changes in the nonthermal parameters on the model spectra are not unique; it is possible to establish two of the three nonthermal parameters only if the third is determined by other means. Using Yohkoh images in conjunction with the fits to BATSE spectra, we calculated upper limits on the length of the region in which the electric field causes runaway electron acceleration. We find that this distance must be shorter than the length of the flaring loop (i.e., less than 3 x 10(9) cm). C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. UNIV OXFORD, OXFORD, ENGLAND. HUGHES STX CORP, VIENNA, VA 22182 USA. RI Holman, Gordon/C-9548-2012; Dennis, Brian/C-9511-2012; Kucera, Therese/C-9558-2012; OI Kucera, Therese/0000-0001-9632-447X NR 35 TC 4 Z9 4 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP 1067 EP 1077 DI 10.1086/177576 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ546 UT WOS:A1996UZ54600042 ER PT J AU Jones, DL Tingay, SJ Murphy, DW Meier, DL Jauncey, DL Reynolds, JE Tzioumis, AK Preston, RA McCulloch, PM Costa, ME Kemball, AJ Nicolson, GD Quick, JFH King, EA Lovell, JEJ Clay, RW Ferris, RH Gough, RG Sinclair, MW Ellingsen, SP Edwards, PG Jones, PA vanOmmen, TD Harbison, P Migenes, V AF Jones, DL Tingay, SJ Murphy, DW Meier, DL Jauncey, DL Reynolds, JE Tzioumis, AK Preston, RA McCulloch, PM Costa, ME Kemball, AJ Nicolson, GD Quick, JFH King, EA Lovell, JEJ Clay, RW Ferris, RH Gough, RG Sinclair, MW Ellingsen, SP Edwards, PG Jones, PA vanOmmen, TD Harbison, P Migenes, V TI Discovery of a subparsec radio counterjet in the nucleus of Centaurus A SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; galaxies, active; galaxies, individual (NGC 5128, Centaurus A); galaxies, jets; galaxies, nuclei ID NGC-5128; NGC-1275; PROBE AB A subparsec scale radio counterjet has been detected in the nucleus of the closest radio galaxy, Centaurus A (NGC 5128), with VLBI imaging at 2.3 and 8.4 GHz. This is one of the first detections of a VLBI counterjet and provides new constraints on the kinematics of the radio jets emerging from the nucleus of Cen A. A bright, compact core is seen at 8.4 GHz, along with a jet extending along P.A. 51 degrees. The core is completely absorbed at 2.3 GHz. Our images show a much wider gap between the base of the main jet and the counterjet at 2.3 GHz than at 8.4 GHz and also that the core has an extraordinarily inverted spectrum. These observations provide evidence that the innermost 0.4-0.8 pc of the source is seen through a disk or torus of ionized gas which is opaque at low frequencies due to free-free absorption. C1 AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,WESTON,ACT 2611,AUSTRALIA. CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. UNIV TASMANIA,HOBART,TAS 7001,AUSTRALIA. HARTEBEESTHOEK RADIO ASTRON OBSERV,ZA-1740 KRUGERSDORP,TRANSVAAL,SOUTH AFRICA. UNIV ADELAIDE,ADELAIDE,SA,AUSTRALIA. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. UNIV WESTERN SYDNEY,KINGSWOOD,NSW,AUSTRALIA. UNIV TASMANIA,ANTARCT COOPERAT RES CTR,HOBART,TAS,AUSTRALIA. BRITISH AEROSP AUSTRALIA,CANBERRA,ACT,AUSTRALIA. NATL ASTRON OBSERV,MITAKA,TOKYO 181,JAPAN. RP Jones, DL (reprint author), CALTECH,JET PROP LAB,MAIL CODE 238-332,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Tingay, Steven/B-5271-2013; van Ommen, Tas/B-5020-2012; King, Edward/A-1473-2012; Ellingsen, Simon/J-7754-2014; Migenes, Victor/F-3157-2015 OI van Ommen, Tas/0000-0002-2463-1718; King, Edward/0000-0002-6898-2130; Ellingsen, Simon/0000-0002-1363-5457; Migenes, Victor/0000-0002-7990-2191 NR 15 TC 33 Z9 33 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP L63 EP L65 DI 10.1086/310183 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ547 UT WOS:A1996UZ54700003 ER PT J AU Turner, MS Truran, JW Schramm, DN Copi, CJ AF Turner, MS Truran, JW Schramm, DN Copi, CJ TI Cosmological implications of the first measurement of the local ISM abundance of He-3 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology, theory; galaxy, abundances; galaxy, evolution; ISM, abundances; nuclear reactions, nucleosynthesis, abundances ID BIG-BANG NUCLEOSYNTHESIS; RED GIANT STARS; INTERSTELLAR-MEDIUM; PRIMORDIAL NUCLEOSYNTHESIS; DEUTERIUM; SOLAR; EVOLUTION; HELIUM; CIRCULATION; C-12/C-13 AB Deuterium plays a crucial role in testing big bang nucleosynthesis. However, its chemical evolution is intertwined with that of He-3. Gloeckler & Geiss's new measurement of the He-3 abundance and the Hubble Space Telescope measurement of D, both in the local ISM today, can be compared to the presolar nebula abundances of D and He-3. Within the uncertainties, the sum of D + He-3 relative to hydrogen is unchanged. This indicates that over the past 4.5 Gyr there has been at most modest stellar production of He-3, in contradiction with stellar modeling, or modest stellar destruction of He-3, in contradiction with efficient ''solar spoons.'' The constancy of D + He-3 alleviates some of the cosmic tension between the big bang He-4 abundance and those of D and He-3. C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP Turner, MS (reprint author), UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637, USA. NR 51 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1996 VL 466 IS 2 BP L59 EP L62 DI 10.1086/310173 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UZ547 UT WOS:A1996UZ54700002 ER PT J AU Lin, YC Bertsch, DL Dingus, BL Esposito, JA Fichtel, CE Fierro, JM Hartman, RC Hunter, SD Kanbach, G Kniffen, DA Mattox, JR MayerHasselwander, HA Michelson, PF vonMontigny, C Mukherjee, R Nolan, PL Radecke, HD Schneid, EJ Sreekumar, P Shriver, SK Thompson, DJ Willis, TD AF Lin, YC Bertsch, DL Dingus, BL Esposito, JA Fichtel, CE Fierro, JM Hartman, RC Hunter, SD Kanbach, G Kniffen, DA Mattox, JR MayerHasselwander, HA Michelson, PF vonMontigny, C Mukherjee, R Nolan, PL Radecke, HD Schneid, EJ Sreekumar, P Shriver, SK Thompson, DJ Willis, TD TI EGRET observations of the region to the south of b=-30 degrees in phase 1 and phase 2 of the Compton Gamma Ray Observatory viewing program SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE galaxies, active; galaxies, individual (NGC 253); gamma rays, observations; globular clusters, individual (47 Tucanae); Magellanic Clouds ID SMALL MAGELLANIC CLOUD; COSMIC-RAYS; TELESCOPE; EMISSION; GALAXIES; RADIATION; PULSARS; LIMITS AB The EGRET telescope aboard the Compton Gamma Ray Observatory has completed the all-sky survey program (phase 1, 1991 April 15 to 1992 November 17) and the following observation program (phase 2, 1992 November 17 to 1993 September 7) in high-energy gamma rays. Analysis of the EGRET data for the region of the sky to the south of the Galactic latitude b = -30 degrees reveals the presence of 13 active galactic nuclei (AGNs) as point sources and four additional point sources that have no obvious counterparts in other wave bands. The Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC), the nearby giant spiral galaxy NGC 253, and 47 Tucanae as a millisecond pulsar candidate for EGRET also fall into this region of the sky. EGRET has detected LMC, but not SMC, NGC 253, or 47 Tuc. Many of these EGRET results have already been published along the way when EGRET observations were carried out. We use now all the available data from phase 1 and phase 2 pointings to update further the positions, spectra, and time variability of these detected EGRET sources and the photon-flux upper limits for some undetected important objects to the south of the galactic latitude b= -30 degrees. These updated EGRET results as well as the previously published results for this region of the sky are now collected together and presented in this paper in a coherent way. The summary results of the EGRET telescope for other regions of the sky will be published separately in other papers. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742. NORTHROP GRUMMAN CORP,BETHPAGE,NY 11714. RP Lin, YC (reprint author), STANFORD UNIV,WW HANSEN EXPT PHYS LAB,STANFORD,CA 94305, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 49 TC 30 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD AUG PY 1996 VL 105 IS 2 BP 331 EP 341 DI 10.1086/192316 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB173 UT WOS:A1996VB17300005 ER PT J AU Vassiliadis, E Dopita, MA Bohlin, RC Harrington, JP Ford, HC Meatheringham, SJ Wood, PR Stecher, TP Maran, SP AF Vassiliadis, E Dopita, MA Bohlin, RC Harrington, JP Ford, HC Meatheringham, SJ Wood, PR Stecher, TP Maran, SP TI Hubble Space Telescope observations of planetary nebulae in the Magellanic Clouds .3. Ultraviolet spectroscopy using the Faint Object Spectrograph SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE dust, extinction; ISM, abundances; Magellanic Clouds; planetary nebulae, general; ultraviolet, ISM ID CENTRAL STARS; OPTICAL SPECTROSCOPY; CARBON ABUNDANCE; RR-TELESCOPII; STELLAR WINDS; LINE LIST; O-IV; IUE; SOLAR; EXTINCTION AB Ultraviolet grating spectra (lambda lambda 1150-2300) of planetary nebulae in the Magellanic Clouds, obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST), are used to identify and measure nebular emission lines and continua, and in one case to detect the stellar wind of the central star. Eight nebulae are observed in the Large Magellanic Cloud (LMC) and four are observed in the Small Magellanic Cloud (SMC). The HST observations are normalized to the photometric scale of ground-based, visible-light spectra (lambda lambda 3400-8000) by means of FOS PRISM observations in the lambda lambda 1350-5100 range. There is an unexplained, systematic discrepancy between the average PRISM and ground fluxes of similar to 30%. Observed and dereddened UV emission-line intensities with respect to H beta are tabulated. The published reddening determinations based on the Balmer decrement are used to deredden the data. In general, the reddening derived from the He II I(1640)/I(4686) emission-line ratio does not agree with that derived from the Balmer decrement. This discrepancy suggests that the two reddening determinations are truly not equal, or that the applied reddening law deviates from the published average LMC or SMC curves. The uncertainty in the relative PRISM to ground calibration also contributes to the discrepancy but is of less importance than the uncertainty associated with the adopted reddening. The reddening is also determined from the lambda 2200 interstellar absorption band, assuming the published average Galactic and Magellanic Cloud reddening curves and is found to agree with the reddening determined from the Balmer decrement, in most cases. Otherwise, the reddening is always determined to be less than the Balmer decrement value. The exception to this rule is SRIC-SMP6, which is the most reddened object in the sample. An alternative calibration for the HST data is achieved by assuming that the reddening derived from the He II I(1640)/I(4686) ratio must equal the reddening derived from the Balmer decrement. However, this procedure can only be applied to seven of the 12 objects in the sample. The alternative UV line intensities are also tabulated. Spectra of six of the nebulae are compared with archival IUE observations in the lambda lambda 1200-2000 range. There is satisfactory agreement between the FOS and IUE data for line intensities less than similar to H beta. For stronger lines, the FOS appears to overestimate the measured line fluxes by similar to 30%, which may be due to the uncertainty associated with the PRISM to ground calibration: the effect is not seen in the smaller fluxes because of larger measurement errors. The continuum fluxes agree to within 50%. Color temperatures, derived from the FOS continuum flux ratios, are uncertain by at least a factor of 2 and are not correlated with previously determined Zanstra temperatures. Nebular densities, derived from O IV] and Si III] UV emission-line ratios, are presented. They are larger than densities derived from visible light [O II] and [S II] line ratios, consistent with the premise that the higher ionization species are formed in denser regions, supposedly closer to the central star. Nebular temperatures are determined using the N+ [I(2139) + I(2143)]/[I(6548)+ I(6583)] ratio and are found to be in agreement with the previously published, solely optical N+ temperatures, when the PRISM to ground calibration is used. When the N II] fluxes are scaled with respect to the helium lines, the N+ temperatures reduce to similar to 11,000 K in all instances. Nebular temperatures implied by the O2+ [I(1661) + I(1666)]/I(5007) ratio are consistent with those derived from the I(4363)/I(5007) ratio if the PRISM to ground calibration is used. The high O2+ electron temperatures for SMC-SMP28 and LMC-SMP87 imply that photoionization is not the sole excitation process in the O2+ zone. However, if the UV line fluxes are rescaled such that the reddening from the Balmer decrement and the He II lines agree, then the optically derived temperatures for these two objects appear to be overestimated by similar to 10,000 K. Estimates of the C/O abundance ratio are made for most objects in the sample using the C III] lambda lambda 1907, 1909, O III] lambda lambda 1661, 1666, and [O III] lambda 5007 emission lines. The C/O ratio is anticorrelated with the previously published N/O values, suggesting that the hot bottom burning process operated during the asymptotic giant branch phase. There are four type I objects in the sample, which have the lowest C/O values. The Si/C ratio is also estimated solely from ultraviolet lines. Silicon emission is only detected in the four type I objects. P Cygni-type line profiles are detected in the spectrum for LMC-SMP76 at N v lambda lambda 1239, 1243, O v lambda 1371, and C IV lambda lambda 1548, 1551. The edge velocities derived from these lines are 1000-1500, 800, and 2000 km s(-1), respectively. C1 AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,INST ADV STUDIES,WESTON,ACT 2611,AUSTRALIA. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Vassiliadis, E (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. RI Dopita, Michael/P-5413-2014 OI Dopita, Michael/0000-0003-0922-4986 NR 66 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD AUG PY 1996 VL 105 IS 2 BP 375 EP 400 DI 10.1086/192320 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB173 UT WOS:A1996VB17300009 ER PT J AU Katul, G Hsieh, CI Oren, R Ellsworth, D Phillips, N AF Katul, G Hsieh, CI Oren, R Ellsworth, D Phillips, N TI Latent and sensible heat flux predictions from a uniform pine forest using surface renewal and flux variance methods SO BOUNDARY-LAYER METEOROLOGY LA English DT Article ID COHERENT STRUCTURES; UNSTABLE CONDITIONS; TURBULENT TRANSFER; LAYER TURBULENCE; DECIDUOUS FOREST; WAVELET ANALYSIS; LOCAL ISOTROPY; SHEAR-STRESS; TEMPERATURE; CANOPY AB A surface renewal model that links organized eddy motion to the latent and sensible heat fluxes is tested with eddy correlation measurements carried out in a 13 m tall uniform Loblolly pine plantation in Duke Forest, Durham, North Carolina. The surface renewal model is based on the occurance of ramp-like patterns in the scalar concentration measurements. To extract such ramp-like patterns from Eulerian scalar concentration measurements, a newly proposed time-frequency filtering scheme is developed and tested. The time-domain filtering is carried out using compactly-supported orthonormal wavelets in conjunction with the ''Universal Wavelet Thresholding'' approach of Donoho and Johnstone, while the frequency filtering is carried out by a band-pass sine filter centered around the ramp-occurrence Frequency as proposed by other studies. The method was separately tested for heat and water vapour with good agreement between eddy correlation flux measurements and model predictions. The usefulness of the flux-variance method to predict sensible and latent heat fluxes is also considered. Our measurements suggest that the simple flux-variance method reproduces the measured heat and momentum fluxes despite the fact that the variances were measured within the roughness sublayer and not in the surface layer. Central to the predictions of water vapour fluxes using the flux-variance approach is the similarity between heat and water vapour transport by the turbulent air flow. This assumption is also investigated for this uniform forest terrain. C1 DUKE UNIV,CTR HYDROL SCI,DURHAM,NC 27708. CALTECH,JET PROP LAB,PASADENA,CA 91109. BROOKHAVEN NATL LAB,BIOSYST & PROC SCI DIV,UPTON,NY 11973. RP Katul, G (reprint author), DUKE UNIV,SCH ENVIRONM,DURHAM,NC 27708, USA. RI Katul, Gabriel/A-7210-2008; OI Katul, Gabriel/0000-0001-9768-3693; Ellsworth, David/0000-0002-9699-2272 NR 89 TC 63 Z9 64 U1 1 U2 4 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0006-8314 J9 BOUND-LAY METEOROL JI Bound.-Layer Meteor. PD AUG PY 1996 VL 80 IS 3 BP 249 EP 282 PG 34 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VU198 UT WOS:A1996VU19800003 ER PT J AU Elishakoff, I Li, YW Starnes, JH AF Elishakoff, I Li, YW Starnes, JH TI Imperfection sensitivity due to the elastic moduli in the Roorda-Koiter frame SO CHAOS SOLITONS & FRACTALS LA English DT Article AB In this study, it is demonstrated through a simple example of the Roorda-Koiter frame that the unavoidable dissimilarity in the distribution of elastic moduli may further reduce the load-carrying capacity in addition to the well-recognized effect of initial geometric imperfections. Copyright (C) 1996 Elsevier Science Ltd. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP Elishakoff, I (reprint author), FLORIDA ATLANTIC UNIV,DEPT MECH ENGN,BOCA RATON,FL 33431, USA. NR 15 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0960-0779 J9 CHAOS SOLITON FRACT JI Chaos Solitons Fractals PD AUG PY 1996 VL 7 IS 8 BP 1179 EP 1186 DI 10.1016/0960-0779(96)89778-5 PG 8 WC Mathematics, Interdisciplinary Applications; Physics, Multidisciplinary; Physics, Mathematical SC Mathematics; Physics GA VE495 UT WOS:A1996VE49500003 ER PT J AU Ricca, A Bauschlicher, CW AF Ricca, A Bauschlicher, CW TI The structure and stability of B-n(+) clusters SO CHEMICAL PHYSICS LA English DT Article ID CATIONIC BORON CLUSTERS; GAUSSIAN-BASIS SETS; IONIZATION-POTENTIALS; ELECTRON CORRELATION; DISSOCIATION-ENERGY; WAVE-FUNCTIONS; ABINITIO; DIMER AB The geometries of B-n(+) clusters for n less than or equal to 14 have been optimized using density functional theory with the B3LYP functional. The most stable structure for each cluster is planar or quasi-planar. The B3LYP fragmentation energies are calibrated using coupled cluster theory. Overall, our corrected fragmentation energies are in reasonable agreement with experiment. Our results are compared with previous theoretical results. RP Ricca, A (reprint author), NASA,AMES RES CTR,STC-230-3,MOFFETT FIELD,CA 94035, USA. NR 25 TC 111 Z9 114 U1 2 U2 12 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD AUG 1 PY 1996 VL 208 IS 2 BP 233 EP 242 DI 10.1016/0301-0104(96)00068-7 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UY674 UT WOS:A1996UY67400005 ER PT J AU Prabhakara, C Yoo, JM Maloney, SP Nucciarone, JJ Arking, A Cadeddu, M Dalu, G AF Prabhakara, C Yoo, JM Maloney, SP Nucciarone, JJ Arking, A Cadeddu, M Dalu, G TI Examination of 'global atmospheric temperature monitoring with satellite microwave measurements' .2. Analysis of satellite data SO CLIMATIC CHANGE LA English DT Article ID EL-NINO; RAINFALL; TRENDS; OCEANS; SMMR AB Using Microwave Sounding Unit (MSU) channel 2 (Ch. 2, 53.74 GHz) data, Spencer and Christy (1992a) determined that the earth exhibits no temperature trend in the period 1979-90, while other authors find a temperature increase of roughly 0.1 K. Based on a theoretical analysis Prabhakara et al. (1995) showed that the information about the global atmospheric temperature deduced from MSU Ch. 2 observations has a small contamination, delta T-2, as a result of the attenuation due to hydrometeors in the atmosphere. A method is developed in this study, that utilizes coincident measurements made by MSU in Ch. 1 (50.3 GHz), to estimate this delta T-2 over the global oceans. The magnitude of delta T-2 is found to be about 1 K over significant parts of the tropical oceanic rain belts and about 0.25 K over minor portions of the mid-latitude oceanic storm tracks. Due to events such as El Nioo, there is variability from year to year in the rain areas and rain intensity leading to significant change in the patterns of delta T-2. The patterns of delta T-2 derived for March 82 and March 83 reveal such a change. When averaged over the global oceans, from 50 degrees N to 50 degrees S, delta T-2 has a value of 0.25 and 0.29 K for March 1982 and 1983, respectively. Due to these reasons the interannual temperature change derived by Spencer and Christy from MSU Ch. 2 will contain a residual hydrometeor effect. Thus in evaluating decadal trend of the global mean temperature of the order of 0.1 K from MSU Ch. 2 data one has to take into account completely the contamination due to hydrometeors. C1 EWHA WOMANS UNIV,SEOUL,SOUTH KOREA. HUGHES STX CORP,GREENBELT,MD 20770. JOHNS HOPKINS UNIV,DEPT EARTH & PLANETARY SCI,BALTIMORE,MD 21218. CNR,AREA RECERIA,CAGLIARI,ITALY. RP Prabhakara, C (reprint author), NASA,GODDARD SPACE FLIGHT CTR,USRA,CODE 913,GREENBELT,MD 20771, USA. NR 14 TC 6 Z9 6 U1 1 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD AUG PY 1996 VL 33 IS 4 BP 459 EP 476 DI 10.1007/BF00141699 PG 18 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA VG027 UT WOS:A1996VG02700003 ER PT J AU Spencer, RW Christy, JR Grody, NC AF Spencer, RW Christy, JR Grody, NC TI Analysis of 'examination of ''global atmospheric temperature monitoring with satellite microwave measurements''' - Comment SO CLIMATIC CHANGE LA English DT Article ID RADIOSONDE VALIDATION; SOUNDING UNIT; PRECIPITATION; RADIOMETER; PRECISION; ANOMALIES; MSU AB The potential for residual hydrometeor contamination effects in the global temperature time series produced by Spencer and Christy from MSU channel 2 (MSU2) data has been addressed by Prabhakara et al. (1995, 1996). They use tropical oceanic MSU channel 1 (MSU1) data to estimate the hydrometeor effects on MSU2. We present several lines of evidence to show that their technique greatly overestimates the hydrometeor effects on MSU2. This overestimation is due to the faulty assumption that the hydrometeors that cause MSU1 warming are the same as (or always exist with) the hydrometeors that cause cooling in MSU2. Instead, the hydrometeors responsible for MSU1 warming are liquid phase, while those responsible for MSU2 cooling are large ice particles. Because liquid phase clouds are much more widespread than the large-ice portions of deep convective systems, their method greatly overestimates the areal coverage of contaminated tropical MSU2 data. In addition, we show that the convective screening procedure of Spencer and Christy removes the negative correlation between MSU1 and MSU2 their conclusions rest upon. Radiosonde validation of monthly tropical MSU2 anomalies over the tropical West Pacific also support these conclusions. C1 UNIV ALABAMA,GLOBAL HYDROL & CLIMATE CTR,HUNTSVILLE,AL 35806. NOAA,NATL ENVIRONM SATELLITE DATA & INFORMAT SERV,WASHINGTON,DC 20233. RP Spencer, RW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,GLOBAL HYDROL & CLIMATE CTR,977 EXPLORER BLVD,HUNTSVILLE,AL 35806, USA. NR 19 TC 8 Z9 8 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD AUG PY 1996 VL 33 IS 4 BP 477 EP 489 DI 10.1007/BF00141700 PG 13 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA VG027 UT WOS:A1996VG02700004 ER PT J AU Prabhakara, C Cadeddu, M Yoo, JM Arking, A Dalu, G AF Prabhakara, C Cadeddu, M Yoo, JM Arking, A Dalu, G TI Examination of 'global atmospheric temperature monitoring with satellite microwave measurements' .3. Cloud and rain contamination - Response SO CLIMATIC CHANGE LA English DT Article AB Observations in channel 1 (Ch. 1, 50.3 GHz) and channel 2 (Ch. 2, 53.74 GHz) of the Microwave Sounding Unit (MSU) over the convective areas of tropical oceans are analysed to reveal the nature of extinction (contamination) in these data. From this analysis we find Ch. 2 data are not free from the influence of clouds and rain, Extinction due to clouds and rain manifests primarily as emission in Ch. 1, and as absorption in Ch. 2. Scattering due to hydrometeors in these channels apparently is of secondary importance, Furthermore we show, in the convective areas of tropical oceans, contamination due to hydrometeors in MSU Ch. 2 data is significant and it is extensive in area. Based on this study we conclude Spencer, Christy, and Grody (this issue) underestimate this contamination. C1 EWHA WOMANS UNIV,SEOUL,SOUTH KOREA. JOHNS HOPKINS UNIV,DEPT EARTH & PLANETARY SCI,BALTIMORE,MD 21218. CNR,AREA RECERIA,CAGLIARI,ITALY. RP Prabhakara, C (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,CODE 913,GREENBELT,MD 20771, USA. NR 5 TC 2 Z9 2 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD AUG PY 1996 VL 33 IS 4 BP 491 EP 496 DI 10.1007/BF00141701 PG 6 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA VG027 UT WOS:A1996VG02700005 ER PT J AU Adam, NR Holowczak, R Halem, M Lal, N Yesha, Y AF Adam, NR Holowczak, R Halem, M Lal, N Yesha, Y TI Digital library task force SO COMPUTER LA English DT Article C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MARYLAND BALTIMORE CTY,CTR EXCELLANCE SPACE DATA & INFORMAT SCI,BALTIMORE,MD 21228. RP Adam, NR (reprint author), RUTGERS STATE UNIV,CIMIC,PISCATAWAY,NJ 08855, USA. RI Holowczak, Richard/A-8324-2009 NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0018-9162 J9 COMPUTER JI Computer PD AUG PY 1996 VL 29 IS 8 BP 89 EP 91 DI 10.1109/2.532051 PG 3 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA VC371 UT WOS:A1996VC37100022 ER PT J AU Sridhar, B Chatterji, GB Soni, T AF Sridhar, B Chatterji, GB Soni, T TI Model-based vision for aircraft position determination SO CONTROL ENGINEERING PRACTICE LA English DT Article DE synthetic vision systems; model-based vision; aircraft position determination; image sensitivity; perspective projection ID NAVIGATION AB Passive vision techniques to estimate aircraft position during landing can be developed using a runway model, images acquired by an onboard imaging sensor, orientation information provided by the inertial navigation system and the position estimate provided by devices such as the global positioning system. In this paper expressions are derived for the sensitivity of point features to errors in the position and orientation of the sensor. Using these, the sensitivity of the sensor image to aircraft position and orientation errors along a typical landing glide path are studied. A least-squares technique based on this sensitivity analysis is described for the correction of position and orientation estimates. RP Sridhar, B (reprint author), NASA,AMES RES CTR,STERLING SOFTWARE INC,MAIL STOP 262-3,MOFFETT FIELD,CA 94035, USA. NR 8 TC 6 Z9 6 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0967-0661 J9 CONTROL ENG PRACT JI Control Eng. Practice PD AUG PY 1996 VL 4 IS 8 BP 1153 EP 1159 DI 10.1016/0967-0661(96)00115-3 PG 7 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA VC589 UT WOS:A1996VC58900014 ER PT J AU Lee, KK Davis, TJ AF Lee, KK Davis, TJ TI The development of the Final Approach Spacing Tool (FAST): A cooperative controller-engineer design approach SO CONTROL ENGINEERING PRACTICE LA English DT Article DE air traffic control; automation; human factors; interface; simulation AB Historically, the development of advanced automation for air traffic control in the United States has excluded the input of the air traffic controller until the end of the development process. In contrast, the development of the Final Approach Spacing Tool (FAST), for the terminal area controller, has incorporated the end-user in early, iterative testing. This paper describes controller involvement in three successive phases of system development, tailored to the complexity of the software testing process. In addition, the creation of a Controller Acceptance Rating Scale to aid user assessment and guide system design is described. This approach has enhanced the usability of FAST, and its introduction into the operational environment. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Lee, KK (reprint author), STERLING SOFTWARE INC,PALO ALTO,CA, USA. NR 14 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0967-0661 J9 CONTROL ENG PRACT JI Control Eng. Practice PD AUG PY 1996 VL 4 IS 8 BP 1161 EP 1168 DI 10.1016/0967-0661(96)00116-5 PG 8 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA VC589 UT WOS:A1996VC58900015 ER PT J AU Huang, ZC Wie, CR Na, I Luo, H Mott, DB Shu, PK AF Huang, ZC Wie, CR Na, I Luo, H Mott, DB Shu, PK TI High performance ZnSe photoconductors SO ELECTRONICS LETTERS LA English DT Article DE metal-semiconductor-metal structures; photodetectors; II-VI semiconductors ID GREEN LASER-DIODES AB A high-quality metal-semiconductor-metal photoconductive detector has been fabricated on semi-insulating ZnSe grown by molecular beam epitaxy. The detector has a responsivity of 320 A/W at 480nm under an applied bias of 10V, and a response time of 2.3ms. C1 SUNY BUFFALO,DEPT ELECT & COMP ENGN,AMHERST,NY 14260. SUNY BUFFALO,DEPT PHYS,AMHERST,NY 14260. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Huang, ZC (reprint author), HUGHES STX CORP,7701 GREENBELT RD,SUITE 400,GREENBELT,MD 20770, USA. NR 6 TC 5 Z9 5 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD AUG 1 PY 1996 VL 32 IS 16 BP 1507 EP 1509 DI 10.1049/el:19960971 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA VC805 UT WOS:A1996VC80500056 ER PT J AU Czepiel, P Douglas, E Harriss, R Crill, P AF Czepiel, P Douglas, E Harriss, R Crill, P TI Measurements of N2O from composted organic wastes SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Article ID NITROUS-OXIDE; DENITRIFICATION; SOIL; EMISSIONS; NITRIFICATION AB The current atmospheric mixing ratio of nitrous oxide (N2O), a chemically significant trace gas, is increasing at a rate of 0.25-0.31% yr(-1), apparently well correlated with human activity. Better quantification of all N2O sources is required in efforts to stabilize this rate of increase. N2O emissions from the composting of wastewater sludge and livestock wastes were measured during 1993 and 1994 using enclosure methods. Static chambers were placed on the surface of the compost piles, and N2O mixing ratios within the chamber headspace were measured over time from which fluxes were calculated. The flux measurements resulted in mass-based emission factors of 0.7 g of N2O (dry kg)(-1) and 0.5 g of N2O (dry kg)(-1) for the sludge compost and the livestock waste compost, respectively. The derived emission factors were used in conjunction with recent waste generation and disposal statistics to estimate potential global N2O emissions from the treatment of organic wastes. Livestock waste treatment appears to hold the greatest N2O potential with estimated global emissions of 1.2 x 10(12) g of N2O yr(-1). C1 UNIV NEW HAMPSHIRE,COMPLEX SYST RES CTR,DURHAM,NH 03824. GEI CONSULTANTS INC,CONCORD,NH 03301. NASA,WASHINGTON,DC 20546. OI Crill, Patrick/0000-0003-1110-3059 NR 30 TC 77 Z9 83 U1 5 U2 25 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0013-936X J9 ENVIRON SCI TECHNOL JI Environ. Sci. Technol. PD AUG PY 1996 VL 30 IS 8 BP 2519 EP 2525 DI 10.1021/es950841j PG 7 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA VA637 UT WOS:A1996VA63700039 ER PT J AU Domingo, V Fleck, B Poland, A Gabriel, A Frohlich, C Scherrer, P Wilhelm, K Harrison, R Delaboudiniere, JP Kohl, J Brueckner, G Bertaux, JL Bochsler, P Kunow, H Torsti, J AF Domingo, V Fleck, B Poland, A Gabriel, A Frohlich, C Scherrer, P Wilhelm, K Harrison, R Delaboudiniere, JP Kohl, J Brueckner, G Bertaux, JL Bochsler, P Kunow, H Torsti, J TI The first results from SOHO SO ESA BULLETIN-EUROPEAN SPACE AGENCY LA English DT Article AB SOHO, launched by an Atlas II-AS from Cape Canaveral on 2 December 1995, was inserted into its halo orbit around the L1 Lagrangian point on 14 February, six weeks ahead of schedule. The launch and the orbital manoeuvres were so accurate and efficient that sufficient fuel remains on board to maintain the halo orbit for more than a decade, i.e. for at least twice as long as originally foreseen. Already during their commissioning phase, the SOHO experiments have returned a wealth of data, impressive in terms of both its quality and diversity. Some of the images can be viewed via the SOHO pages (http://sohowww.nascom.nasa.gov) on the World Wide Web, and on the individual experiment pages, all with links from the SOHO home page. Typical examples of the unique results being obtained with SOHO's instruments are presented here. Although they have been obtained with single instruments, it is worth noting that the main scientific advances from SOHO are expected to come from the joint analysis of coordinated observations. RP Domingo, V (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ESA,DEPT SPACE SCI,GREENBELT,MD 20771, USA. RI Fleck, Bernhard/C-9520-2012 NR 0 TC 0 Z9 0 U1 0 U2 0 PU EUROPEAN SPACE AGENCY PI NOORDWIJK PA ESTEC, PO BOX 299, 2200 AG NOORDWIJK, NETHERLANDS SN 0376-4265 J9 ESA BULL-EUR SPACE JI ESA Bull.-Eur. Space Agency PD AUG PY 1996 IS 87 BP 7 EP 24 PG 18 WC Engineering, Aerospace SC Engineering GA VH959 UT WOS:A1996VH95900001 ER PT J AU Rakocinski, CF LyczkowskiShultz, J Richardson, SL AF Rakocinski, CF LyczkowskiShultz, J Richardson, SL TI Ichthyoplankton assemblage structure in Mississippi sound as revealed by canonical correspondence analysis SO ESTUARINE COASTAL AND SHELF SCIENCE LA English DT Article DE larval fish assemblages; marine ichthyoplankton; estuarine nursery; Gulf of Mexico ID SHALLOW MARSH HABITATS; MEXICO BARRIER-ISLAND; CAPE FEAR RIVER; SEASONAL FLUCTUATIONS; LARVAL FISHES; NORTHERN GULF; COMMUNITY STRUCTURE; LOUISIANA ESTUARY; EDGE FISHES; ABUNDANCE AB The spatiotemporal dynamics of the ichthyoplankton assemblage structure were investigated in Mississippi Sound, a northern Gulf of Mexico estuary. The study was based on a comprehensive survey constituting 528 collections from 22 stations over 12 months at two tow depths. Important environmental correlates of assemblage structure were identified using canonical correspondence analysis (CCA). A wide taxonomic diversity was encountered during the ichthyoplankton survey, including 152 taxa distributed among 48 families. Strong physical gradients in water temperature, dissolved oxygen and salinity correlated predominantly with ichthyoplankton assemblage structure, and reflected substantial spatiotemporal variation. The CCA results were interpreted in light of adult life-style characteristics. Ecological groups of larvae, as defined by adult life-style characteristics for respective taxa, showed distinctive dispersion patterns in 2-dimensional canonical space. A diverse group of offshore demersal taxa clustered as larvae in a region of CCA space corresponding spatiotemporally with stations located in passes and outside of the Sound during late summer and autumn. Other ecological groups, such as the inshore nektonic and offshore pelagic fishes, were widely dispersed as larvae in canonical space, with member taxa occurring under dissimilar physical conditions. Estuarine embayments in the north-central Gulf of Mexico, like Mississippi Sound, might: be viewed appropriately as landwardmost sections of the wider, highly productive nursery grounds of this region. (C) 1996 Academic Press Limited C1 SE FISHERIES SCI CTR,NATL MARINE FISHERIES SERV,PASCAGOULA,MS 39568. RP Rakocinski, CF (reprint author), GULF COAST RES LAB,POB 7000,OCEAN SPRINGS,MS 39566, USA. RI Rakocinski, Chet/B-1240-2009 OI Rakocinski, Chet/0000-0002-1552-358X NR 41 TC 51 Z9 60 U1 2 U2 9 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0272-7714 J9 ESTUAR COAST SHELF S JI Estuar. Coast. Shelf Sci. PD AUG PY 1996 VL 43 IS 2 BP 237 EP 257 DI 10.1006/ecss.1996.0067 PG 21 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA VC804 UT WOS:A1996VC80400006 ER PT J AU Ray, RD Mitchum, GT AF Ray, RD Mitchum, GT TI Surface manifestation of internal tides generated near Hawaii SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GEOSAT ALTIMETRY; BAROCLINIC TIDES; OCEAN TIDES; TOPEX/POSEIDON AB Analysis of Topex/Poseidon satellite altimetry reveals short-wavelength fluctuations in the ocean surface tide that are attributable to internal tides. A significant fraction of the semidiurnal internal tide generated at the Hawaiian Ridge is evidently phase-locked to the astronomical potential and can modulate the amplitude of the surface tide by similar to 5 cm. The internal tide is thus easily mapped along satellite groundtracks, and it is found to be spatially coherent over great distances, with waves propagating well over 1000 km from the Hawaiian Ridge before decaying below noise level. Both first and second baroclinic modes are observed in both the M(2) (lunar) and S-2 (solar) tides. The high space-time coherence is in sharp contrast to what is often inferred from current-meter observations, but it confirms recent speculations from an acoustic experiment north of Hawaii. C1 UNIV S FLORIDA,DEPT MARINE SCI,ST PETERSBURG,FL 33701. RP Ray, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,CODE 926,GREENBELT,MD 20771, USA. RI Ray, Richard/D-1034-2012 NR 18 TC 160 Z9 162 U1 2 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 1996 VL 23 IS 16 BP 2101 EP 2104 DI 10.1029/96GL02050 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VA620 UT WOS:A1996VA62000026 ER PT J AU Tabazadeh, A Toon, OB Gary, BL Bacmeister, JT Schoberl, MR AF Tabazadeh, A Toon, OB Gary, BL Bacmeister, JT Schoberl, MR TI Observational constraints on the formation of Type Ia polar stratospheric clouds SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TEMPERATURE-FLUCTUATIONS; LIDAR OBSERVATIONS; AEROSOLS AB On January 11, 1989 during AASE I, Type Ia polar stratospheric clouds (PSCs) were observed over a vast area in the Arctic. Synoptic scale temperature histories for this flight are obtained using the Goddard trajectory model. Mesoscale temperature fluctuations (MTF) are divided into two major categories of background and lee waves. The statistics of background MTFs are derived from measurements by the microwave temperature profiler aboard the ER-2 aircraft. A forecast model is used to determine the occurrence of lee waves. The MTFs are then superimposed upon the Goddard synoptic scale temperatures. Statistical correlations between temperature histories and Type Ia PSC observations indicate that MTFs can not be solely responsible for the formation of Type Ia PSCs in the stratosphere. Instead, on a synoptic scale, the exposure time of air masses to temperatures below the nitric acid trihydrate (NAT) frost point for similar to 1 day or more should be the main criteria for predicting the occurrence of Type Ia clouds in the stratosphere. C1 USN,RES LAB,WASHINGTON,DC 20375. CALTECH,JET PROP LAB,PASADENA,CA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Tabazadeh, A (reprint author), NASA,AMES RES CTR,MS 245-4,MOFFETT FIELD,CA 94035, USA. NR 15 TC 47 Z9 48 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 1996 VL 23 IS 16 BP 2109 EP 2112 DI 10.1029/96GL01998 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VA620 UT WOS:A1996VA62000028 ER PT J AU Herman, JR Bhartia, PK Ziemke, J Ahmad, Z Larko, D AF Herman, JR Bhartia, PK Ziemke, J Ahmad, Z Larko, D TI UV-B increases (1979-1992) from decreases in total ozone SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ULTRAVIOLET-RADIATION; SATELLITE ESTIMATION; TRENDS; SURFACE; IRRADIANCE; REFLECTIVITY; DEPLETION; CLOUDS AB Increases in ultraviolet fluxes (300 nm to 340 nm) reaching the ground between 1979 and 1992 are estimated using measured stratospheric ozone amounts and reflectivity data from Nimbus-7/TOMS (Total Ozone Mapping Spectrometer). The UV increases are estimated from an ozone data set obtained using a new algorithm incorporating improved in-flight instrument calibration. The 380 nm radiance data are used to show that there were no changes in ultraviolet atmospheric albedo due to clouds and aerosols from 1979 to 1992 within the 1% uncertainty of the measurements. Linear least squares fits to the monthly and annual increases in UV exposure since 1979 are given for 3 wavelengths (300 nm, 310 nm, and 320 nm) that are strongly, moderately, and weakly absorbed by ozone. The estimated linear changes for the 3 wavelengths become significant (2 standard deviations) poleward of about 40 degrees latitude. In the 45 degrees +/- 5 degrees latitude band, the slope of linear fits to the annual zonally averaged changes for these wavelengths are about 13%, 3%, and 1% per decade in the southern hemisphere, and 10%, 3%, and 1% per decade in the northern hemisphere. Similarly derived values are estimated for DNA, plant, end erythema action spectra. Monthly values of exposure changes are larger towards higher latitudes and during the spring and winter months (e.g., 8.6%, 9.8%, and 5.1% per decade during April at 45 degrees N). Erythemal UV-increases obtained from TOMS data disagree with previously determined ground based UV-decreases from an average of 8 U.S. Robertson-Berger sites. C1 SOFTWARE CORP AMER,GREENBELT,MD. HUGHES STX CORP,GREENBELT,MD. RP Herman, JR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NRC,CODE 916,GREENBELT,MD 20771, USA. RI Bhartia, Pawan/A-4209-2016; OI Bhartia, Pawan/0000-0001-8307-9137; Herman, Jay/0000-0002-9146-1632 NR 24 TC 194 Z9 202 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 1996 VL 23 IS 16 BP 2117 EP 2120 DI 10.1029/96GL01958 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VA620 UT WOS:A1996VA62000030 ER PT J AU Wescott, EM Sentman, DD Heavner, MJ Hampton, DL Osborne, DL Vaughan, OH AF Wescott, EM Sentman, DD Heavner, MJ Hampton, DL Osborne, DL Vaughan, OH TI Blue starters: Brief upward discharges from an intense Arkansas thunderstorm SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SPRITES94 AIRCRAFT CAMPAIGN; STRATOSPHERE AB This paper documents the first observations of a new stratospheric electrical phenomenon associated with thunderstorms. On the night of 30 June (UT 1 July) 1994, 30 examples of these events, which we have called ''blue starters,'' were observed in a 6 m 44 s interval above the very energetic Arkansas thunderstorm where blue jets were first observed. The blue starters are distinguished from blue jets by a much lower terminal altitude. They are bright and blue in color, and protrude upward from the cloud top (17-18 km) to a maximum 25.5 km (83,655 ft.) in altitude. All blue starters events were recorded from two small areas near Texarkana, Texas/Arkansas where hail 7.0 cm in diameter was falling. Comparison to cloud-to-ground (CG) lightning flashes revealed: 1. Blue starters were not observed to be coincident with either positive or negative CG flashes, but they do occur in the same general area as negative CG flashes; 2. Cumulative distributions of the negative CG flashes in +/- 5 s before and after the starter and within a radius of 50 km shows a significant reduction for about 3 s following the event in the two cells where starters and jets were observed. The energy deficit is approximately 10(9) J. It is possible that blue starters are a short-lived streamer phenomenon. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35806. RP Wescott, EM (reprint author), UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK 99775, USA. NR 17 TC 56 Z9 58 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 1996 VL 23 IS 16 BP 2153 EP 2156 DI 10.1029/96GL01969 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VA620 UT WOS:A1996VA62000039 ER PT J AU Meriwether, JW Mirick, JL Biondi, MA Herrero, FA Fesen, CG AF Meriwether, JW Mirick, JL Biondi, MA Herrero, FA Fesen, CG TI Evidence for orographic wave heating in the equatorial thermosphere at solar maximum SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FABRY-PEROT-INTERFEROMETER; GENERAL-CIRCULATION MODEL; VERTICAL WINDS; GRAVITY-WAVES; ATMOSPHERE; MIDDLE AB Fabry Perot interferometer observations of equatorial 630 nm airglow thermospheric winds and temperatures were made at Arequipa, Peru (16.5 S, 71.5 W) during the solar maximum years of 1989 and 1990. Examination of the thermospheric winds measured from Doppler shifts of the 630 nm airglow emission in the two directions east and west of Arequipa shows that the zonal wind is often significantly weaker over the Andes (east) than over the Pacific (west) in winter. Between 19 LT and 24 LT, the typical reductions in speed found were similar to 40 to 70 m/s. In the same time period the temperature results show elevated values of similar to 200-500 K for the three directions (north, east, and zenith) over mountainous terrain compared with those ol the two directions (west and south) over water. This effect fades near equinoctial periods. Examination of the standard deviation of the temperature observations for the five directions showed an increase in this value above the measurement error by a factor of three for the direction toward the Andes (East) but not for the direction over water (South); this elevation is consistent with wave activity as a source of the heating. Viscous dissipation of waves propagating into the thermosphere region from below is suggested as an explanation for the localized regions of heating. C1 UNIV PITTSBURGH,DEPT PHYS & ASTRON,PITTSBURGH,PA 15260. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20940. DARTMOUTH COLL,DEPT PHYS,HANOVER,NH 03755. RP Meriwether, JW (reprint author), CLEMSON UNIV,DEPT PHYS & ASTRON,CLEMSON,SC 29634, USA. NR 23 TC 27 Z9 27 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 1996 VL 23 IS 16 BP 2177 EP 2180 DI 10.1029/96GL01976 PG 4 WC Geosciences, Multidisciplinary SC Geology GA VA620 UT WOS:A1996VA62000045 ER PT J AU Hall, DK AF Hall, DK TI Remote sensing applications to hydrology: Imaging radar SO HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES LA English DT Article ID SYNTHETIC-APERTURE-RADAR; SOIL-MOISTURE; ERS-1 SAR; ENVIRONMENTAL-CONDITIONS; BOREAL FOREST; SNOW; PERMAFROST; VEGETATION; IMAGERY AB Synthetic Aperture Radar (SAR) data are very useful for hydrological studies because the dielectric properties of materials are generally dependent on the amount of liquid water in the material, and this affects the strength of the radar backscatter, sigma degrees. Additionally, the ability of microwaves to penetrate the surface of many materials often permits analysis of subsurface properties. Further, SAR sensors can image the Earth through both clouds and darkness which enables dynamic hydrological events, e.g. floods, to be captured. Both radar system parameters and surface characteristics affect sigma degrees. In the case of snow, sigma degrees is the sum of the surface scattering at the air/snow interface, volume scattering within the snowpack, scattering at the snow/soil interface and volumetric scattering from the underlying surface (if applicable). For glaciers, sigma degrees is dominated by scattering from the surface and is dependent upon the roughness of the glacier surface in relationship to the radar wavelength. Imaging radar is proving to be an important tool for measuring flooding beneath a variety of herbaceous and woody vegetation. Use of multi-frequency and multi-polarization sensors is necessary to improve the accuracy of mapping flooded vs non-flooded land in floodplains. SAR data have been shown to have potential for measuring stream discharge in braided rivers and for studying key characteristics of frozen lakes. Work with polarimetric SAR data is becoming increasingly significant in hydrological studies. RP Hall, DK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,LAB HYDROSPHER PROC,GREENBELT,MD 20771, USA. RI Hall, Dorothy/D-5562-2012 NR 56 TC 17 Z9 17 U1 2 U2 11 PU IAHS PRESS, INST HYDROLOGY PI WALLINGFORD PA C/O SARAH CAGE, WALLINGFORD, ENGLAND OX10 8BB SN 0262-6667 J9 HYDROLOG SCI J JI Hydrol. Sci. J.-J. Sci. Hydrol. PD AUG PY 1996 VL 41 IS 4 BP 609 EP 624 DI 10.1080/02626669609491528 PG 16 WC Water Resources SC Water Resources GA UZ648 UT WOS:A1996UZ64800011 ER PT J AU Engman, ET AF Engman, ET TI Remote sensing applications to hydrology: Future impact SO HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES LA English DT Article ID MODEL AB The case is made that the hydrological sciences are data limited and that future progress in understanding hydrological processes is hampered by the lack of adequate data. The future applications of remote sensing to hydrology should provide new types of data that enable hydrologists to address the previously unsolved questions. RP Engman, ET (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,LAB HYDORSPHER PROC,GREENBELT,MD 20771, USA. NR 14 TC 17 Z9 19 U1 0 U2 3 PU IAHS PRESS, INST HYDROLOGY PI WALLINGFORD PA C/O SARAH CAGE, WALLINGFORD, ENGLAND OX10 8BB SN 0262-6667 J9 HYDROLOG SCI J JI Hydrol. Sci. J.-J. Sci. Hydrol. PD AUG PY 1996 VL 41 IS 4 BP 637 EP 647 DI 10.1080/02626669609491530 PG 11 WC Water Resources SC Water Resources GA UZ648 UT WOS:A1996UZ64800013 ER PT J AU Romani, PN AF Romani, PN TI Recent rate constant and product measurements of the reactions C2H3+H-2 and C2H3+H - Importance for photochemical modeling of hydrocarbons on Jupiter SO ICARUS LA English DT Article ID KINETIC DATA; ACETYLENE; ETHANE; METHANE; STRATOSPHERE; ATMOSPHERES; HYDROGEN; CHANNELS; NEPTUNE; RATIOS AB Recently the rate constants of the reactions C2H3 + H-2 --> C2H4 + H and C2H3 + H --> products have been measured by more direct methods than used previously. The new determination for the rate constant of C2H3 + H-2 is lower by a factor of 1000 at room temperature than the rate used by Allen et al. in their methane photochemical model (The relative abundance of ethane to acetylene in the jovian stratosphere, Icarus 100, 527-533 (1992)). A fast rate for this reaction is key to their proposed reaction scheme to convert C2H2 to C2H6 and explain the C2H6/C2H2 ratio on Jupiter. However, their scheme becomes ineffective when a rate constant expression consistent with Fahr et al. is used (Experimental determination of the rate constant for the reaction of C2H3 with H-2 and implications for the partitioning of hydrogen in the atmospheres of the other planets, Icarus 116, 415-422 (1995)). The rate measurement for C2H3 + H by Monks et al. (Kinetics and products of the reaction between H and C2H2 of T = 213 and 298 K, J. Phys. Chem. 99, 17,151-17,159 (1993)) is consistent with recent measurements but they found C2H4 to be a significant product, in addition to C2H2 + H-2 only the latter product channel had been used in methane photochemical models. With the new lower rate constant for C2H3 + H-2, the reaction C2H3 + H --> C2H4 becomes important in determining the C2H6/C2H2 ratio on Jupiter. However, the new reaction scenario is less efficient in converting C2H2 to C2H6 than the one proposed by Alien et al. because it depends in part upon H, which is in scarce supply in the lower stratosphere where C2H3 + H --> C2H4 is important. (C) 1996 Academic Press, Inc. RP Romani, PN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Romani, Paul/D-2729-2012 NR 27 TC 46 Z9 46 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1996 VL 122 IS 2 BP 233 EP 241 DI 10.1006/icar.1996.0122 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VD780 UT WOS:A1996VD78000002 ER PT J AU Estrada, PR Cuzzi, JN AF Estrada, PR Cuzzi, JN TI Voyager observations of the color of Saturn's rings SO ICARUS LA English DT Article ID PARTICLE EROSION MECHANISMS; PHOTOMETRIC PROPERTIES; BALLISTIC TRANSPORT; SIZE DISTRIBUTIONS; B-RING; TITAN; SPECTROPHOTOMETRY; CONSTRAINTS; OCCULTATION; SATELLITES AB Previously unreduced high-resolution Voyager 2 images of Saturn's main rings are used to generate reflectivity (I/F) profiles as a function of radius. Ratios of profiles taken from green, violet, orange, and UV filter images are then produced. The I/F ratios are a diagnostic of composition and provide us with information on the rings' present state of compositional evolution. The rings are extremely reddish in color which suggests that they could not be pure water ice. In addition, we find that the C ring and Cassini division are, in fact, less red or more neutral in color than the A and B rings. This is contrary to the impression given by the familiar enhanced Voyager color images which represent them falsely as bluish in color. The most likely candidate for the non-icy components are silicates and organics. The sources of these pollutants are of extreme importance in determining the compositional history of the rings. The radial profiles of ring color ratio exhibit several very interesting properties; (a) broad-scale, fairly smooth, color variations which are only weakly correlated with underlying ring structure (optical depth variations) across the outer C ring and inner B rings as well as the Cassini division region; these variations are probably consistent with ballistic transport; (b) fine-scale, noise-like (but unquestionably real) color variations across at least the outer two-thirds of the B ring. Not only the ''redness'' but also the spectral shape varies. These variations are currently unexplained. Ground-based spectroscopic observations should be pursued to study the implied compositional heterogeneities on at least the larger scales. This data set will be used for modeling of the color and composition of the main rings using ballistic transport and radiative transfer theories. We have provided true and false color visualizations of the rings generated from the one-dimensional (I/F) profiles and color ratios, respectively. The overall color of the rings is an extremely pale tan, and subtle color variations in the B ring are evident to the unaided eye upon careful inspection. (C) 1996 Academic Press, Inc. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Estrada, PR (reprint author), STANFORD UNIV,DEPT PHYS,STANFORD,CA 94309, USA. NR 54 TC 30 Z9 30 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1996 VL 122 IS 2 BP 251 EP 272 DI 10.1006/icar.1996.0124 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VD780 UT WOS:A1996VD78000004 ER PT J AU Berenji, HR AF Berenji, HR TI Computational intelligence and soft computing for space applications SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB Systems using computational intelligence and soft computing have been successfully developed for many industrial and space applications. These systems seek to emulate the type of reasoning that humans perform when solving complex tasks. The field of soft computing, as defined by Zadeh- the inventor of fuzzy logic - encompasses fuzzy logic as well as other methodologies such as neural networks, genetic algorithms, and uncertainty management, It is expected that soft-computing techniques will eventually become as common and prevalent as traditional methods of computer science. This paper presents an overview of applications of fuzzy logic and soft computing to space projects. The role of fuzzy systems that can learn from experience to improve their performance is discussed. We present a report on applications of these adaptive systems to NASA space projects such as the orbital operations of the Space Shuttle, which include attitude control and rendezvous/docking operations. We also provide insights on the future of computational intelligence and soft computing and of their vast potential in industrial applications. RP Berenji, HR (reprint author), NASA,AMES RES CTR,INTELLIGENT INFERENCE SYST CORP,DIV COMPUTAT SCI,MS 269-2,MOFFETT FIELD,CA 94035, USA. NR 22 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 SN 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD AUG PY 1996 VL 11 IS 8 BP 8 EP 10 DI 10.1109/62.533748 PG 3 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA VC470 UT WOS:A1996VC47000004 ER PT J AU Romanofsky, RR AF Romanofsky, RR TI On the relationship between Schottky barrier capacitance and mixer performance at cryogenic temperatures SO IEEE MICROWAVE AND GUIDED WAVE LETTERS LA English DT Article AB The flat-hand voltage is the Schottky junction voltage required to shrink the depletion width to zero, At cryogenic temperatures, mixer diodes are generally biased and/or pumped beyond the Rat-hand condition to minimize conversion loss and noise figure, This occurs despite the presumed sharp increase in junction capacitance near flat-band, which should instead limit mixer performance. Past moderate forward bias, the diode C-V relationship is difficult to measure, A simple analytic expression for C(V) is usually used to model and predict mixer performance, This letter provides experimental data on C(V) at 77 K based on a microwave measurement and modeling technique, Data is also provided on the conversion loss of a singly balanced mixer optimized for 77 K operation, The connection between junction capacitance, flat-hand potential, and conversion loss is examined. It is shown that the analytic expression greatly overestimates the junction capacitance that occurs as flat-band is approached. RP Romanofsky, RR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 8 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 SN 1051-8207 J9 IEEE MICROW GUIDED W JI IEEE Microw. Guided Wave Lett. PD AUG PY 1996 VL 6 IS 8 BP 286 EP 288 DI 10.1109/75.508555 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA UY956 UT WOS:A1996UY95600004 ER PT J AU Laheurte, JM Katehi, LPB Rebeiz, GM AF Laheurte, JM Katehi, LPB Rebeiz, GM TI CPW-fed slot antennas on multilayer dielectric substrates SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article ID INTEGRALS; ELEMENTS; DIPOLE; ARRAYS AB Coplanar wave (CPW)-fed slot antennas printed on multilayer dielectric substrates are numerically analyzed using a full-wave integral equation technique and the method of moments. The Green's function is derived with an iterative formulation, Results obtained with a simplified and a rigorous model of the feeding CPW lines are compared, The mutual coupling between slot antennas in an array environment is calculated for a three-layer high-low-high permittivity combination, Theoretical results are verified with measurements. RP Laheurte, JM (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 18 TC 25 Z9 25 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD AUG PY 1996 VL 44 IS 8 BP 1102 EP 1111 DI 10.1109/8.511818 PG 10 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA VB608 UT WOS:A1996VB60800007 ER PT J AU Kory, CL AF Kory, CL TI Three-dimensional simulation of helix traveling-wave tube cold-test characteristics using MAFIA SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article AB The cold-test parameters including dispersion, impedance, and attenuation have been calculated for a helix traveling-wave tube (TWT) slow-wave circuit using MAFIA, the three-dimensional (3-D) electromagnetic finite-integration computer code. The helix model includes tape thickness, rectangular dielectric supports, and material properties consistent with the actual circuit. Measured cold-test data and computer-derived results for the helix circuit are presented with excellent agreement. RP Kory, CL (reprint author), ANALEX CORP,NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 6 TC 12 Z9 17 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD AUG PY 1996 VL 43 IS 8 BP 1317 EP 1319 DI 10.1109/16.506790 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA UZ976 UT WOS:A1996UZ97600026 ER PT J AU Otoshi, TY Franco, MM AF Otoshi, TY Franco, MM TI The electrical conductivities of steel and other candidate materials for shrouds in a beam-waveguide antenna system (vol 45, pg 77, 1996) SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Correction, Addition RP Otoshi, TY (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 1 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 SN 0018-9456 J9 IEEE T INSTRUM MEAS JI IEEE Trans. Instrum. Meas. PD AUG PY 1996 VL 45 IS 4 BP 839 EP 839 DI 10.1109/TIM.1996.517007 PG 1 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA UW846 UT WOS:A1996UW84600013 ER PT J AU Gedney, SD Lansing, FS Rascoe, DL AF Gedney, SD Lansing, FS Rascoe, DL TI Full wave analysis of microwave monolithic circuit devices using a generalized Yee-algorithm based on an unstructured grid SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID FDTD ALGORITHM; DISCONTINUITIES; EQUATIONS AB A generalized Yee-algorithm is presented for the temporal full-wave analysis of microwave monolithic integrated circuit (MMIC) devices, This algorithm has the significant advantage over the traditional Yee-algorithm in that it is based on unstructured and irregular grids, Thus, using the generalized Yee-algorithm, MMIC devices that contain curved conductors or complex geometries can be more accurately and conveniently modeled using standard automatic grid generation techniques, The generalized Yee-algorithm is based on the time-marching solution of the discrete form of Maxwell's equations in their integral form, A correction scheme is introduced that is stable, maintains second-order accuracy, and maintains the divergenceless nature of the flux densities, Furthermore, by structuring the algorithm as a series of sparse matrix-vector multiplications, the generalized Yee-algorithm can be efficiently implemented on vector or parallel high performance computers. C1 CALTECH,JET PROP LAB,SPACECRAFT TELECOMMUN EQUIPMENT SECT,PASADENA,CA 91109. RP Gedney, SD (reprint author), UNIV KENTUCKY,DEPT ELECT ENGN,LEXINGTON,KY 40506, USA. RI Gedney, Stephen/I-5590-2012 NR 18 TC 35 Z9 35 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD AUG PY 1996 VL 44 IS 8 BP 1393 EP 1400 DI 10.1109/22.536021 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA VC774 UT WOS:A1996VC77400001 ER PT J AU Edmonds, LD AF Edmonds, LD TI A graphical method for estimating charge collected by diffusion from an ion track SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article ID DEVICES; SILICON AB The diffusion equation has some applications relevant to charge collection from ion tracks in silicon devices. This problem has been treated in the past for eases in which the entire upper surface can be represented as a sink for minority carriers, The present paper treats the case in which there are a number of disconnected upper junctions separated by reflective surfaces. Numerical results, presented as plots of charge-collection efficiency contours, are given for several device geometries. Such plots, combined with a simple superposition, provide charge-collection estimates for arbitrary track length, location, and direction, The mathematical theory applies to any geometry and can be used by the reader to obtain additional plots and/or analytical expressions. The diffusion coefficient can be an arbitrary function of carrier density. RP Edmonds, LD (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 11 TC 11 Z9 11 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD AUG PY 1996 VL 43 IS 4 BP 2346 EP 2357 DI 10.1109/23.531783 PN 2 PG 12 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA VD778 UT WOS:A1996VD77800003 ER PT J AU Samet, H Soffer, A AF Samet, H Soffer, A TI MARCO: MAp Retrieval by COntent SO IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE LA English DT Article DE map storage and retrieval; document storage; digital libraries; automated indexing; retrieval by content; map interpretation; Geographic Information Systems (GIS) ID RECOGNITION AB A system named MARCO (denoting MAp Retrieval by COntent) that is used for the acquisition, storage, indexing, and retrieval of map images is presented. The input to MARCO are raster images of separate map layers and raster images of map composites. A legend-driven map interpretation system converts map layer images from their physical representation to their logical representation. This logical representation is then used to automatically index both the composite and the layer images. Methods for incorporating logical and physical layer images as well as composite images into the framework of a relational database management system are described. Indices are constructed on both the contextual and the spatial data thereby enabling efficient retrieval of layer and composite images based on contextual as well as spatial specifications. Example queries and query processing strategies using these indices are described. The user interface is demonstrated via the execution of an example query. Results of an experimental study on a large amount of data are presented. The system is evaluated in terms of accuracy and in terms of query execution time. C1 UNIV MARYLAND, CTR AUTOMAT RES, COLLEGE PK, MD 20742 USA. UNIV MARYLAND, INST ADV COMP SCI, COLLEGE PK, MD 20742 USA. UNIV MARYLAND, DEPT COMP SCI & ELECT ENGN, BALTIMORE, MD 21228 USA. NASA, GODDARD SPACE FLIGHT CTR, CTR EXCELLENCE SPACE DATA & INFORMAT SCI, GREENBELT, MD 20771 USA. RP UNIV MARYLAND, DEPT COMP SCI, COLLEGE PK, MD 20742 USA. NR 32 TC 31 Z9 31 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 EI 1939-3539 J9 IEEE T PATTERN ANAL JI IEEE Trans. Pattern Anal. Mach. Intell. PD AUG PY 1996 VL 18 IS 8 BP 783 EP 798 DI 10.1109/34.531799 PG 16 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA VE318 UT WOS:A1996VE31800003 ER PT J AU Chien, SA Mortensen, HB AF Chien, SA Mortensen, HB TI Automating image processing for scientific data analysis of a large image database SO IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE LA English DT Article DE data analysis; image processing; artificial intelligence (AI); planning; automated programming AB This article describes the Multimission VICAR Planner (MVP): an Al planning system which uses knowledge about image processing steps and their requirements to construct executable image processing scripts to support high-level science requests made to the Jet Propulsion Laboratory (JPL) Multimission Image Processing Subsystem (MIPS). This article describes a general Al planning approach to automation and application of the approach to a specific area of image processing for planetary science applications involving radiometric correction, color triplet reconstruction, and mosaicing in which the MVP system significantly reduces the amount of effort required by image processing experts to fill a typical request. RP Chien, SA (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 18 TC 19 Z9 19 U1 0 U2 2 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0162-8828 J9 IEEE T PATTERN ANAL JI IEEE Trans. Pattern Anal. Mach. Intell. PD AUG PY 1996 VL 18 IS 8 BP 854 EP 859 DI 10.1109/34.531806 PG 6 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA VE318 UT WOS:A1996VE31800010 ER PT J AU Buyevich, YA Webbon, BW AF Buyevich, YA Webbon, BW TI Dynamics of vapour bubbles in nucleate boiling SO INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER LA English DT Article ID GROWTH RATES; PREDICTION AB This paper considers the behaviour of a vapour bubble formed at a nucleation site on a heated horizontal wall. This bubble is modeled as a spherical segment which is separated from the wall by a microlayer of intervening liquid. The liquid is presumed to be at rest at great distances from the bubble. In order to avoid unwarranted assumptions about forces acting on the bubble which are specific to all known models of bubble growth and detachment, we derive equations that govern bubble behaviour in a rigorous way from the variational equation that describes mechanical energy conservation for the whole system, which includes both the bubble and the liquid. The variational equation leads to a set of two mutually independent strongly nonlinear equations which govern bubble expansion and the motion of its centre of mass. Because these equations contain an extra unknown variable (the bubble vapour pressure), a supplementary equation that defines bubble vapour temperature must be formulated with allowance made for heat transfer to the bubble both from the bulk of the surrounding liquid and through the microlayer. The most important conclusion of this paper consists in the fact that surface tension effects result in an effective force that tends to transform the bubble into a sphere, thereby facilitating bubble detachment. This conclusion absolutely nullifies the generally, however erroneously, held belief that this effective force presses the bubble to the wall. By way of example, we consider the evolution of bubbles whose growth is thermally controlled. Our analysis provides quite a natural explanation for a number of repeatedly observed phenomena, such as the influence of gravity and surface tension on bubble growth rate and the dependence of bubble detachment size on thermophysical parameters. Copyright (C) 1996 Elsevier Science Ltd. RP Buyevich, YA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 24 TC 27 Z9 31 U1 0 U2 7 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0017-9310 J9 INT J HEAT MASS TRAN JI Int. J. Heat Mass Transf. PD AUG PY 1996 VL 39 IS 12 BP 2409 EP 2426 DI 10.1016/0017-9310(95)00345-2 PG 18 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA UN285 UT WOS:A1996UN28500004 ER PT J AU Sterling, T Savarese, D Merkey, P Olson, K AF Sterling, T Savarese, D Merkey, P Olson, K TI An empirical evaluation of the convex SPP-1000 hierarchical shared memory system SO INTERNATIONAL JOURNAL OF PARALLEL PROGRAMMING LA English DT Article DE parallel processing; performance evaluation; cache coherence; shared memory multiprocessor; scalability AB Cache coherency in a scalable parallel computer architecture requires mechanisms beyond the conventional common bus based snooping approaches which are limited to about 16 processors. The new Convex SPP-1000 achieves cache coherency across 128 processors through a two-level shared memory NUMA structure employing directory based and SCI protocol mechanisms. While hardware support for managing a common global name space minimizes overhead costs and simplifies programming, latency considerations for remote accesses may still dominate and can under unfavorable conditions constrain scalability. This paper provides the first published evaluation of the SP-1000 hierarchical cache coherency mechanisms from the perspective of measured latency and its impact on basic global flow control mechanisms, scaling of a parallel science code, and sensitivity of cache miss rates to system scale. It is shown that global remote access latency is only a factor of seven greater than that of local cache miss penalty and that scaling of a challenging scientific application is not severely degraded by the hierarchical structure for achieving consistency across the system processor caches. C1 UNIV MARYLAND, DEPT COMP SCI, COLLEGE PK, MD 20742 USA. GEORGE MASON UNIV, INST COMPUTAT SCI & INFORMAT, FAIRFAX, VA 22030 USA. RP Sterling, T (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CTR EXCELLENCE SPACE DATA & INFORMAT SCI, CODE 9305, GREENBELT, MD 20771 USA. NR 16 TC 2 Z9 2 U1 0 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0885-7458 J9 INT J PARALLEL PROG JI Int. J. Parallel Program. PD AUG PY 1996 VL 24 IS 4 BP 377 EP 396 PG 20 WC Computer Science, Theory & Methods SC Computer Science GA VE259 UT WOS:A1996VE25900004 ER PT J AU Cucka, P Netanyahu, NS Rosenfeld, A AF Cucka, P Netanyahu, NS Rosenfeld, A TI Learning in navigation: Goal finding in graphs SO INTERNATIONAL JOURNAL OF PATTERN RECOGNITION AND ARTIFICIAL INTELLIGENCE LA English DT Article DE goal finding; learning; navigation; random graphs AB A robotic agent operating in an unknown and complex environment may employ a search strategy of some kind to perform a navigational task such as reaching a given goal. In the process of performing the task, the agent can attempt to discover characteristics of its environment that enable it to choose a more efficient search strategy for that environment. If the agent is able to do this, we can say that it has ''learned to navigate'' -- i.e., to improve its navigational performance. This paper describes how an agent can learn to improve its goal-finding performance in a class of discrete spaces, represented by graphs embedded in the plane. We compare several basic search strategies on two different classes of ''random'' graphs and show how information collected during the traversal of a graph can be used to classify the graph, thus allowing the agent to choose the search strategy best suited for that graph. C1 UNIV MARYLAND,CTR AUTOMAT RES,COMP VIS LAB,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,CTR EXCELLENCE SPACE DATA & INFORMAT SCI,GREENBELT,MD 20771. NR 17 TC 11 Z9 11 U1 0 U2 0 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 9128, SINGAPORE SN 0218-0014 J9 INT J PATTERN RECOGN JI Int. J. Pattern Recognit. Artif. Intell. PD AUG PY 1996 VL 10 IS 5 BP 429 EP 446 DI 10.1142/S0218001496000281 PG 18 WC Computer Science, Artificial Intelligence SC Computer Science GA VV206 UT WOS:A1996VV20600004 ER PT J AU Srinivasan, J Smith, GL AF Srinivasan, J Smith, GL TI Meridional migration of tropical convergence zones SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID LOW-FREQUENCY VARIABILITY; MONSOON; DYNAMICS; DROUGHT; BUDGET; MODEL; CLOUD AB Outgoing longwave radiation data from the Earth Radiation Budget Experiment show that the meridional migration of tropical convergence zones (TCZ) varies greatly from one region to another in the Tropics. In Africa, the meridional migration of TCZ is limited due to the meridional variation of the planetary net radiation due to the Sahara Desert. The large meridional migration in the Asian subcontinent and the west Pacific Ocean is attributed to the strong land-sea contrast in these regions. The wind-evaporation feedback mechanism is proposed as the cause of intraseasonal meridional migration of TCZ in the Atlantic and east Pacific Oceans. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. INDIAN INST SCI,CTR ATMOSPHER SCI,BANGALORE 560012,KARNATAKA,INDIA. NR 19 TC 20 Z9 20 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD AUG PY 1996 VL 35 IS 8 BP 1189 EP 1202 DI 10.1175/1520-0450(1996)035<1189:MMOTCZ>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VE128 UT WOS:A1996VE12800002 ER PT J AU Crosson, WL Duchon, CE Raghavan, R Goodman, SJ AF Crosson, WL Duchon, CE Raghavan, R Goodman, SJ TI Assessment of rainfall estimates using a standard Z-R relationship and the probability matching method applied to composite radar data in central Florida SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID CONVECTIVE RAINFALL; TROPICAL RAINFALL; AREA INTEGRALS; REFLECTIVITY; HEIGHT AB Precipitation estimates from radar systems are a crucial component of many hydrometeorological applications, from flash flood forecasting to regional water budget studies. For analyses on large spatial scales and long timescales, it is frequently necessary to use composite reflectivities from a network of radar systems. Such composite products are useful for regional or national studies, but introduce a set of difficulties not encountered when using single radars. For instance, each contributing radar has its own calibration and scanning characteristics, but radar identification may not be retained in the compositing procedure. As a result, range effects on signal return cannot be taken into account. This paper assesses the accuracy with which composite radar imagery can be used to estimate precipitation in the convective environment of Florida during the summer of 1991. Results using Z = 300R(1.4) (WSR-88D default Z-R relationship) are compared with those obtained using the probability matching method (PMM). Rainfall derived from the power law Z-R was found to be highly biased (+90%-110%) compared to rain gauge measurements for various temporal and spatial integrations. Application of a 36.5-dBZ reflectivity threshold (determined via the PMM) was found to improve the performance of the power law Z-R, reducing the biases substantially to 20%-33%. Correlations between precipitation estimates obtained with either Z-R relationship and mean gauge values are much higher for areal averages than for point locations. Precipitation estimates from the PMM are an improvement over those obtained using the power law in that biases and root-mean-square errors are much lower. The minimum timescale for application of the PMM with the composite radar dataset was found to be several days for area-average precipitation. The minimum spatial scale is harder to quantify, although it is concluded that it is less than 350 km(2). Implications relevant to the WSR-88D system are discussed. C1 INST GLOBAL CHANGE RES & EDUC,HUNTSVILLE,AL. UNIV OKLAHOMA,SCH METEOROL,NORMAN,OK 73019. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NR 26 TC 24 Z9 24 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD AUG PY 1996 VL 35 IS 8 BP 1203 EP 1219 DI 10.1175/1520-0450(1996)035<1203:AOREUA>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VE128 UT WOS:A1996VE12800003 ER PT J AU Yoganathan, M Choyke, WJ Devaty, RP Neudeck, PG AF Yoganathan, M Choyke, WJ Devaty, RP Neudeck, PG TI Free to bound transition-related electroluminescence in 3C and 6H SiC p(+)-n junctions at room temperature SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SIDE-BY-SIDE; DIODES AB The room temperature electroluminescence spectra of moderately nitrogen doped (1x10(17) cm(-3)) 3C and 6H SiC p(+)-n junctions are studied as a function of forward current. The free to bound transition due to the unintentional, deep boron (defect) center is dominant at low forward bias, while the free to bound transitions due to nitrogen donors and aluminum accepters are dominant at higher forward biases. These results can be explained using Shockley-Read-Hall analysis of the recombination rate as a function of bias. The origin of boron related electroluminescence is suggested to be primarily from recombination within the depletion region, while aluminum and nitrogen related electroluminescence is attributed to recombinations in the minority carrier injection regions. (C) 1996 American Institute of Physics. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Yoganathan, M (reprint author), UNIV PITTSBURGH,DEPT PHYS & ASTRON,PITTSBURGH,PA 15260, USA. NR 15 TC 12 Z9 12 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD AUG 1 PY 1996 VL 80 IS 3 BP 1763 EP 1767 DI 10.1063/1.362974 PG 5 WC Physics, Applied SC Physics GA VA594 UT WOS:A1996VA59400075 ER PT J AU King, MD Menzel, WP Grant, PS Myers, JS Arnold, GT Platnick, SE Gumley, LE Tsay, SC Moeller, CC Fitzgerald, M Brown, KS Osterwisch, FG AF King, MD Menzel, WP Grant, PS Myers, JS Arnold, GT Platnick, SE Gumley, LE Tsay, SC Moeller, CC Fitzgerald, M Brown, KS Osterwisch, FG TI Airborne scanning spectrometer for remote sensing of cloud, aerosol, water vapor, and surface properties SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID MODIS; SCIENCE AB An airborne scanning spectrometer was developed for measuring reflected solar and emitted thermal radiation in 50 narrowband channels between 0.55 and 14.2 mu m. The instrument provides multispectral images of outgoing radiation for purposes of developing and validating algorithms for the remote sensing of cloud, aerosol, water vapor, and surface properties from space. The spectrometer scans a swath width of 37 km, perpendicular to the aircraft flight track, with a 2.5-mrad instantaneous field of view. Images are thereby produced with a spatial resolution of 50 m at nadir from a nominal aircraft altitude of 20 km. Nineteen of the spectral bands correspond closely to comparable bands on the Moderate Resolution Imaging Spectroradiometer (MODIS), a facility instrument being developed for the Earth Observing System to be launched in the late 1990s. This paper describes the optical, mechanical, electrical, and data acquisition system design of the MODIS Airborne Simulator and presents some early results obtained from measurements acquired aboard the National Aeronautics and Space Administration ER-2 aircraft that illustrate the performance and quality of the data produced by this instrument. C1 UNIV WISCONSIN,NOAA,NESDIS,MADISON,WI. NASA,AMES RES CTR,ATAC,MOFFETT FIELD,CA 94035. APPL RES CORP,GODDARD SPACE FLIGHT CTR,GREENBELT,MD. RES & DATA SYST CORP,GODDARD SPACE FLIGHT CTR,GREENBELT,MD. UNIV WISCONSIN,COOPERAT INST METEOROL SATELLITE STUDIES,MADISON,WI. DAEDALUS ENTERPRISES INC,ANN ARBOR,MI. RP King, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 900,GREENBELT,MD 20771, USA. RI Menzel, W. Paul/B-8306-2011; King, Michael/C-7153-2011; Tsay, Si-Chee/J-1147-2014; Platnick, Steven/J-9982-2014 OI Menzel, W. Paul/0000-0001-5690-1201; King, Michael/0000-0003-2645-7298; Platnick, Steven/0000-0003-3964-3567 NR 23 TC 153 Z9 154 U1 0 U2 6 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD AUG PY 1996 VL 13 IS 4 BP 777 EP 794 DI 10.1175/1520-0426(1996)013<0777:ASSFRS>2.0.CO;2 PG 18 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA UY962 UT WOS:A1996UY96200001 ER PT J AU Heymsfield, GM Bidwell, SW Caylor, IJ Ameen, S Nicholson, S Boncyk, W Miller, L Vandemark, D Racette, PE Dod, LR AF Heymsfield, GM Bidwell, SW Caylor, IJ Ameen, S Nicholson, S Boncyk, W Miller, L Vandemark, D Racette, PE Dod, LR TI The EDOP radar system on the high-altitude NASA ER-2 aircraft SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID MICROWAVE OBSERVATIONS; AIRBORNE; PRECIPITATION; RAIN; LINE AB The NASA ER-2 high-altitude (20 km) aircraft that emulates a satellite view of precipitation systems carries a variety of passive and active (lidar) remote sensing instruments. A new Doppler weather radar system at X band (9.6 GHz) called the ER-2 Doppler radar (EDOP) has been developed and flown on the ER-2 aircraft. EDOP is a fully coherent Doppler weather radar with fixed nadir and forward pointing (33 degrees off nadir) beams that map out Doppler winds and reflectivities in the vertical plane along the aircraft motion vector. Doppler winds from the two beams can be used to derive vertical and along-track air motions. In addition, the forward beam provides linear depolarization measurements that are useful in discriminating microphysical characteristics of the precipitation. This paper deals with a general description of the EDOP instrument including the measurement concept, the system configuration and hardware, and recently obtained data examples from the instrument. The combined remote sensing package on the ER-2, along with EDOP, provides a unique platform for simulating spaceborne remote sensing of precipitation. C1 SCI SYST & APPLICAT INC,LANHAM,MD. TRW CO INC,REDONDO BEACH,CA 90278. USGS,EROS DATA CTR,SIOUX FALLS,SD. CLEMSON UNIV,CLEMSON,SC. WALLOPS FLIGHT FACIL,WALLOPS ISL,VA. SWALES INC,BELTSVILLE,MD. RP Heymsfield, GM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 912,GREENBELT,MD 20771, USA. NR 38 TC 68 Z9 70 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD AUG PY 1996 VL 13 IS 4 BP 795 EP 809 DI 10.1175/1520-0426(1996)013<0795:TERSOT>2.0.CO;2 PG 15 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA UY962 UT WOS:A1996UY96200002 ER PT J AU Green, RN Avis, LM AF Green, RN Avis, LM TI Validation of ERBS scanner radiances SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article ID RADIATION BUDGET EXPERIMENT; RADIOMETERS; SATELLITE AB The earth radiation budget satellite (ERBS) has made broadband scanner measurements of the earth radiance for over 5 years. The redundancy between the shortwave, longwave, and total scanning radiometers and data averages have been used to validate the long-term consistency among the measurements and to establish how measurement drift has affected the archived top-of-the-atmosphere fluxes. The total channel gain at night was found to be unchanged over a 4-yr test period. Relative to the total channel at night, the longwave channel sensitivity decreased by 0.5% over the same 4 years and the shortwave channel was unchanged. The shortwave part of the total channel, however, gradually increased in gain by 1.3%. Only the daytime longwave flux was affected by these changes. It drifted upward depending on the scene shortwave component. Over 4 years, the clear ocean daytime longwave flux increased by 0.2% and overcast scenes by 2.6%. For all scenes in the Tropics, the daytime longwave flux increased by less than 1% in 4 years. There was no statistical evidence that the daytime shortwave or nighttime longwave fluxes had drifted. RP Green, RN (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,CODE 420,HAMPTON,VA 23681, USA. NR 17 TC 20 Z9 20 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD AUG PY 1996 VL 13 IS 4 BP 851 EP 862 DI 10.1175/1520-0426(1996)013<0851:VOESR>2.0.CO;2 PG 12 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA UY962 UT WOS:A1996UY96200005 ER PT J AU Moursi, AM Globus, RK Lull, JC Damsky, CH AF Moursi, AM Globus, RK Lull, JC Damsky, CH TI Integrin receptors for fibronectin regulate osteogenesis. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 UNIV CALIF SAN FRANCISCO,DEPT MED,SAN FRANCISCO,CA. UNIV CALIF SAN FRANCISCO,DEPT STOMATOL,SAN FRANCISCO,CA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 1 U2 1 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP 172 EP 172 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49500172 ER PT J AU Evans, GL MoreyHolton, E Turner, RT AF Evans, GL MoreyHolton, E Turner, RT TI Spaceflight has compartment specific effects on mRNA levels for bone matrix proteins and bone matrix production in rat femur. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. MAYO CLIN,DEPT ORTHOPED RES,ROCHESTER,MN. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP M353 EP M353 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49500699 ER PT J AU Kiratli, BJ Yamada, M Smith, A Marcus, RM Amaud, S vanderMeulen, MCH AF Kiratli, BJ Yamada, M Smith, A Marcus, RM Amaud, S vanderMeulen, MCH TI Differences in femoral geometry and structure due to immobilization. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 VA HLTH CARE SYST,PALO ALTO,CA 94304. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI van der Meulen, Marjolein/D-1549-2010 OI van der Meulen, Marjolein/0000-0001-6637-9808 NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP M564 EP M564 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49500910 ER PT J AU Malouvier, ACL Zerath, E MoreyHolton, E AF Malouvier, ACL Zerath, E MoreyHolton, E TI Hypergravity prevents age-related trabecular bone loss in young rat tibiae. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 CERMA,IMASSA,F-91223 BRETIGNY SUR ORGE,FRANCE. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP M349 EP M349 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49500695 ER PT J AU Navidi, M Evans, J LooftWilson, R Wolinsky, I Arnaud, SB AF Navidi, M Evans, J LooftWilson, R Wolinsky, I Arnaud, SB TI Calcium balance in mature rats exposed to a space flight model. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV HOUSTON,HOUSTON,TX 77204. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP M570 EP M570 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49500917 ER PT J AU Arnaud, SB Hutchinson, TM Bakulin, AV Rahkmanov, AS Steele, CR AF Arnaud, SB Hutchinson, TM Bakulin, AV Rahkmanov, AS Steele, CR TI Differences in mechanical properties of the human and monkey tibia. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. INST BIOMED PROBLEMS,MOSCOW,RUSSIA. STANFORD UNIV,STANFORD,CA 94305. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP T424 EP T424 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49501241 ER PT J AU Breit, GA Goldberg, BK Whalen, RT AF Breit, GA Goldberg, BK Whalen, RT TI Determination of small animal long bone areal properties using densitometry SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP T415 EP T415 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49501231 ER PT J AU Halloran, BP Bikle, DD Harris, J Tanner, S Curren, T MoreyHolton, E AF Halloran, BP Bikle, DD Harris, J Tanner, S Curren, T MoreyHolton, E TI Regional responsiveness of the tibia to intermittent administration of PTH as affected by skeletal unloading. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 UNIV CALIF SAN FRANCISCO,VET AFFAIRS MED CTR,SAN FRANCISCO,CA 94121. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP T619 EP T619 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49501435 ER PT J AU PattersonBuckendahl, P Poppalardo, D Kvetnansky, R Globus, R Bikle, D Halloran, B MoreyHolton, E AF PattersonBuckendahl, P Poppalardo, D Kvetnansky, R Globus, R Bikle, D Halloran, B MoreyHolton, E TI Opposing effects of vitamin D and stress hormones on bone osteocalcin concentration SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 STOCKTON STATE COLL,POMONA,NJ 08240. SLOVAK ACAD SCI,BRATISLAVA,SLOVAKIA. UNIV CALIF SAN FRANCISCO,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP T503 EP T503 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49501319 ER PT J AU Westerlind, KC MoreyHolton, E Evans, GK Tanner, SJ Turner, RT AF Westerlind, KC MoreyHolton, E Evans, GK Tanner, SJ Turner, RT TI TGF-beta may help couple mechanical strain and bone cell activity in vivo. SO JOURNAL OF BONE AND MINERAL RESEARCH LA English DT Meeting Abstract C1 AMC,CTR CANC RES,DENVER,CO. MAYO CLIN,ROCHESTER,MN. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU BLACKWELL SCIENCE INC PI CAMBRIDGE PA 238 MAIN ST, CAMBRIDGE, MA 02142 SN 0884-0431 J9 J BONE MINER RES JI J. Bone Miner. Res. PD AUG PY 1996 VL 11 SU 1 BP T312 EP T312 PG 1 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA VA495 UT WOS:A1996VA49501130 ER PT J AU Curry, JA Rossow, WB Randall, D Schramm, JL AF Curry, JA Rossow, WB Randall, D Schramm, JL TI Overview of Arctic cloud and radiation characteristics SO JOURNAL OF CLIMATE LA English DT Article ID GENERAL-CIRCULATION MODEL; REGIONAL CLIMATE MODEL; SEA-ICE ALBEDO; ATMOSPHERIC WATER-VAPOR; OPTICAL-PROPERTIES; STRATUS CLOUDS; SURFACE-TEMPERATURE; SOLAR-RADIATION; BOUNDARY-LAYER; SENSITIVITY EXPERIMENT AB To provide a background for ARM's activities at the North Slope of Alaska/Adjacent Arctic Ocean sites, an overview is given of our current state of knowledge of Arctic cloud and radiation properties and processes. The authors describe the Arctic temperature and humidity characteristics, cloud properties and processes, radiative characteristics of the atmosphere and surface, direct and indirect radiative effects of aerosols, and the modeling and satellite remote sensing of cloud and radiative characteristics. An assessment is given of the current performance of satellite remote sensing and climate modeling in the Arctic as related to cloud and radiation issues. Radiation-climate feedback processes are discussed, and estimates are made of the sign and magnitude of the individual feedback components. Future plans to address these issues are described. C1 NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. COLORADO STATE UNIV, FT COLLINS, CO 80523 USA. RP UNIV COLORADO, CTR ENGN, DEPT AEROSP ENGN SCI, CAMPUS BOX 429, BOULDER, CO 80309 USA. RI Rossow, William/F-3138-2015 NR 274 TC 406 Z9 420 U1 8 U2 54 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 EI 1520-0442 J9 J CLIMATE JI J. Clim. PD AUG PY 1996 VL 9 IS 8 BP 1731 EP 1764 DI 10.1175/1520-0442(1996)009<1731:OOACAR>2.0.CO;2 PG 34 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VG921 UT WOS:A1996VG92100005 ER PT J AU Murtugudde, R Seager, R Busalacchi, A AF Murtugudde, R Seager, R Busalacchi, A TI Simulation of the tropical oceans with an ocean GCM coupled to an atmospheric mixed-layer model SO JOURNAL OF CLIMATE LA English DT Article ID SEA-SURFACE TEMPERATURE; GENERAL-CIRCULATION MODEL; PACIFIC-OCEAN; INDIAN-OCEAN; SEASONAL CYCLE; EQUATORIAL PACIFIC; REDUCED-GRAVITY; EL-NINO; PRIMITIVE EQUATION; BOUNDARY-LAYER AB A reduced gravity, primitive equation, ocean general circulation model (GCM) is coupled to an advective atmospheric mixed-layer (AML) model to demonstrate the importance of a nonlocal atmospheric mixed-layer parameterization for a proper simulation of surface heat fluxes and sea surface temperatures (SST). Seasonal variability of the model SSTs and the circulation are generally in good agreement with the observations in each of the tropical oceans. These results are compared to other simulations that use a local equilibrium mixed-layer model. Inclusion of the advective AML model is demonstrated to lead to a significant improvement in the SST simulation in all three oceans. Advection and diffusion of the air humidity play significant roles in determining SSTs even in the tropical Pacific where the local equilibrium assumption was previously deemed quite accurate. The main, and serious, model flaw is an inadequate representation of the seasonal cycle in the upwelling regions of the eastern Atlantic and Pacific Oceans. The results indicate that the feedback between mixed-layer depths and SSTs can amplify SST errors, implying that increased realism in the modeling of the ocean mixed layer increases the demand for realism in the representation of the surface heat fluxes. The performance of the GCM with a local-equilibrium mixed-layer model in the Atlantic is as poor as previous simple ocean model simulations of the Atlantic. The conclusion of earlier studies that the simple ocean model was at fault may, in fact, not be correct. Instead the local-equilibrium heat flux parameterization appears to have been the major source of error. Accurate SST predictions may, hence, be feasible by coupling the AML model to computationally efficient simple ocean models. C1 COLUMBIA UNIV,LAMONT DOHERTY EARTH OBSERV,PALISADES,NY. RP Murtugudde, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,LAB HYDROSPHER PROC,CODE 970,BLDG 22,GREENBELT,MD 20771, USA. NR 69 TC 105 Z9 105 U1 1 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD AUG PY 1996 VL 9 IS 8 BP 1795 EP 1815 DI 10.1175/1520-0442(1996)009<1795:SOTTOW>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VG921 UT WOS:A1996VG92100008 ER PT J AU Lillywhite, HB Ballard, RE Hargens, AR AF Lillywhite, HB Ballard, RE Hargens, AR TI Cardiovascular responses of semi-arboreal snakes to chronic, intermittent hypergravity SO JOURNAL OF COMPARATIVE PHYSIOLOGY B-BIOCHEMICAL SYSTEMIC AND ENVIRONMENTAL PHYSIOLOGY LA English DT Article DE hypergravity; carotid blood flow; acceleration tolerance; cardiovascular acclimation; snake, Elaphe obsoleta ID PLASMA-CORTICOSTERONE LEVELS; AMERICAN ALLIGATOR; ELAPHE-OBSOLETA; BLOOD-PRESSURE; HEMORRHAGE; GRAVITY AB Cardiovascular functions were studied in semi-arboreal rat snakes (Elaphe obsoleta) following long-term, intermittent exposure to + 1.5 G(z) (head-to-tail acceleration) on a centrifuge. Snakes were held in a nearly straight position within horizontal plastic tubes during periods of centrifugation. Centrifugal acceleration, therefore, subjected snakes to a linear force gradient with the maximal force being experienced at the tail. Compared to non-centrifuged controls, G(z)-acclimated snakes showed greater increases of heart rate during head-up tilt or acceleration, greater sensitivity of arterial pressure to circulating catecholamines, higher blood levels of corticosterone, and higher blood ratios of prostaglandin F-2 alpha/prostaglandin E(2). Cardiovascular tolerance to increased gravity during graded G(z) acceleration was measured as the maximum (caudal) acceleration force at which carotid arterial blood flow became null. When such tolerances were adjusted for effects of body size and other continuous variables incorporated into an analysis of covariance, the difference between the adjusted mean values of control and acclimated snakes (2.37 and 2.84 G(z), respectively) corresponded closely to the 0.5 G difference between the acclimation G (1.5) and Earth gravity (1.0). As in other vertebrates, cardiovascular tolerance to G(z) stress tended to be increased by acclimation, short body length, high arterial pressure, and comparatively large blood volume. Voluntary body movements were important for promoting carotid blood how at the higher levels of G(z) stress. C1 NASA,AMES RES CTR,GRAVITAT RES BRANCH,MOFFETT FIELD,CA 94035. NR 36 TC 3 Z9 4 U1 2 U2 4 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0174-1578 J9 J COMP PHYSIOL B JI J. Comp. Physiol. B-Biochem. Syst. Environ. Physiol. PD AUG PY 1996 VL 166 IS 4 BP 241 EP 253 DI 10.1007/BF00262868 PG 13 WC Physiology; Zoology SC Physiology; Zoology GA VG122 UT WOS:A1996VG12200001 PM 11540396 ER PT J AU Adams, NA Shariff, K AF Adams, NA Shariff, K TI A high-resolution hybrid compact-ENO scheme for shock-turbulence interaction problems SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID FINITE-DIFFERENCE SCHEMES; HYPERBOLIC CONSERVATION-LAWS; DIRECT NUMERICAL-SIMULATION; BOUNDARY-VALUE PROBLEMS; EFFICIENT IMPLEMENTATION; CAPTURING SCHEMES; LAYER FLOWS; STABILITY; APPROXIMATIONS AB A class of upwind-biased finite-difference schemes with a compact stencil is proposed in general form, suitable for the time-accurate direct numerical simulation of fluid-convection problems. These schemes give uniformly high approximation order and allow for a spectral-like wave resolution while dissipating non-resolved wavenumbers. When coupled with an essentially non-oscillatory scheme near discontinuities, the compact schemes become shock-capturing and their resolution properties are preserved. The derivation of the compact schemes is discussed in detail. Their convergence and resolution properties as well as numerical stability are analyzed. Upwinding and coupling procedures are described. Application examples for typical non-linear wave interaction problems are given. (C) 1996 Academic Press, Inc. C1 NASA,AMES RES CTR,CTR TURBULENCE RES,MOFFETT FIELD,CA 94035. RI Adams, Nikolaus/H-7247-2014; OI Adams, Nikolaus/0000-0001-5048-8639; Shariff, Karim/0000-0002-7256-2497 NR 52 TC 209 Z9 227 U1 1 U2 8 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1996 VL 127 IS 1 BP 27 EP 51 DI 10.1006/jcph.1996.0156 PG 25 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA VB430 UT WOS:A1996VB43000004 ER PT J AU Kim, GT Lin, JT Jones, OC Glicksman, ME Duval, WMB Singh, NB AF Kim, GT Lin, JT Jones, OC Glicksman, ME Duval, WMB Singh, NB TI Effects of convection during the physical vapor transport process: Application of laser Doppler velocimetry SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID CRYSTAL-GROWTH; PURIFICATION; ENCLOSURES AB Experimental studies have been conducted on the effects of convection in the physical vapor transport (PVT) process of Hg2Cl2 using a laser Doppler velocimetry (LDV) technique to make in situ velocity measurements of the vapor phase in closed ampoules, The experiments are performed in closed cylindrical ampoules with an aspect ratio (diameter-to-height) of 0.12 in a two-zone furnace, The experimental data obtained indicate that the local velocity profiles of Hg2Cl2 vapor measured at a fixed location are asymmetrical and have a cellular flow pattern, which provides evidence of convection. The magnitude of the axial velocity is 0-4 cm/s. C1 RENSSELAER POLYTECH INST,DEPT MAT ENGN,TROY,NY 12180. RENSSELAER POLYTECH INST,DEPT NUCL ENGN & ENGN PHYS,TROY,NY 12180. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. WESTINGHOUSE SCI & TECHNOL CTR,PITTSBURGH,PA 15235. OI Glicksman, Martin/0000-0002-2675-2759 NR 31 TC 12 Z9 12 U1 0 U2 2 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 AUG PY 1996 VL 165 IS 4 BP 429 EP 437 DI 10.1016/0022-0248(96)00196-0 PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA VC072 UT WOS:A1996VC07200012 ER PT J AU Korpela, SA Ni, J Chait, A Kassemi, M AF Korpela, SA Ni, J Chait, A Kassemi, M TI Radiative heat transfer in fiber drawing and crystal pulling SO JOURNAL OF CRYSTAL GROWTH LA English DT Article AB An analysis of the cooling of semi-transparent thin fibers and larger diameter crystals that are grown from their melts has been carried out. Both conduction and radiation heat transfer are considered and the radiation theory is tailored for materials which absorb weakly, Using the differential approximation for the radiative transport, a solution valid in the optically thin limit is obtained for fibers. An improved solution that is applicable for crystals of larger diameter is also developed. C1 NASA,LEWIS RES CTR,DIV MAT,CLEVELAND,OH 44135. RP Korpela, SA (reprint author), OHIO STATE UNIV,DEPT MECH ENGN,206 W 18TH AVE,COLUMBUS,OH 43210, USA. NR 13 TC 7 Z9 7 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD AUG PY 1996 VL 165 IS 4 BP 455 EP 462 DI 10.1016/0022-0248(96)00194-7 PG 8 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA VC072 UT WOS:A1996VC07200015 ER PT J AU Neugebauer, M Goldstein, BE Smith, EJ Feldman, WC AF Neugebauer, M Goldstein, BE Smith, EJ Feldman, WC TI Ulysses observations of differential alpha-proton streaming in the solar wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MINOR IONS; HELIUM; ACCELERATION; HYDROGEN; SHOCK AB Data from the solar wind spectrometer on the Ulysses spacecraft are used to study the differential streaming between the alpha particles and protons in the solar wind over the heliographic distance range of 1.3 to 5.4 AU and latitudes from 0 degrees to +/- 80 degrees during the period December 1990 through September 1995. The study is based on 6-hour averages of the parameter V-alpha p = \V-alpha - V-p\ where V-alpha and V-p are the vector velocities of the alpha particles and protons, respectively. it is found that V-alpha p decreases with increasing distance from the Sun and with decreasing solar wind speed. The distance and velocity dependencies can be combined into a single dependence on travel time T from the Sun to the point of observation, with V-alpha p declining, on the average, as T--0.70+/-0.07. After normalization by this travel time factor, there is no residual dependence of V-alpha p on heliographic latitude thus ruling out any rotational effects on either the acceleration or deceleration of the alphas relative to the protons. There is also no significant difference in the normalized values of V-alpha p between quasi-stationary and transient (coronal mass ejection) flows. The ratios V-alpha p/V-wave where V-A is the Alfven speed, and V-alpha p/V-wave, where V-wave is the observed propagation speed of Alfvenic fluctuations, both decline with increasing distance from the Sun, but V-alpha p/V-wave remains in the range of 1.0 to 1.5 out to a travel time of 5 or 10 days. There are weak correlations between the normalized value of V-alpha p and the amplitudes of fluctuations in both the magnitude and the direction of the interplanetary magnetic field. Although V-alpha p anticorrelates strongly with the ratio of the Coulomb collision time to the solar wind expansion time, it is believed that the correlation is not evidence of a cause and effect relation between those two parameters over much of the solar wind regime observed by Ulysses. Where comparisons are possible, the Ulysses data closely agree with extrapolations of the Helios data to greater solar distances. C1 LOS ALAMOS NATL LAB,LOS ALAMOS,NM. RP Neugebauer, M (reprint author), CALTECH,JET PROPULS LAB,PASADENA,CA, USA. NR 25 TC 59 Z9 59 U1 3 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1996 VL 101 IS A8 BP 17047 EP 17055 DI 10.1029/96JA01406 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB700 UT WOS:A1996VB70000001 ER PT J AU Mecherikunnel, AT AF Mecherikunnel, AT TI Solar total irradiance observations from spacecraft: 1992-1993 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RADIOMETERS; VARIABILITY; EURECA; BOARD AB A brief review of the simultaneous observations of solar total irradiance performed by the UARS ACRIM II (upper atmosphere research satellite active cavity radiometer irradiance monitor), EURECA SOVA 1 and SOVA 2 (European retrievable carrier platform solar variability experiments), ERBS ERBE (Earth Radiation Budget Satellite Earth Radiation Budget Experiment), Nimbus 7 ERB, and Atlas 1 and 2 in 1992-1993 (a period characterized as the declining phase of solar cycle 22), is presented in this paper. Statistical comparison of the irradiance values and the linear relationships among the time series are examined for the overlap period August 1992 to May 1993. The mean irradiance at 1 astronomical unit (AU) observed by the UARS ACRIM II, EURECA SOVA 1, EURECA SOVA 2, and ERBS ERBE is within the range of 1365.5-1366.9 W m(-2), and high correlation (r(2) = 0.94) exists among the time series. Linear regression models based on the measurements are used in estimating the observed irradiance and predicting the missing values. The challenge in establishing a homogeneous long-term database from the independent observations of shorter duration rr:quires a clear understanding of the compatibility of the data sets and any instrument-related drift or degradation. RP Mecherikunnel, AT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,MAIL CODE 925,GREENBELT,MD 20771, USA. NR 14 TC 3 Z9 3 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1996 VL 101 IS A8 BP 17073 EP 17079 DI 10.1029/96JA01405 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB700 UT WOS:A1996VB70000003 ER PT J AU Liewer, PC Karmesin, SR Brackbill, JU AF Liewer, PC Karmesin, SR Brackbill, JU TI Hydrodynamic instability of the heliopause driven by plasma-neutral charge-exchange interactions SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LOCAL INTERSTELLAR-MEDIUM; SOLAR-WIND; RADIO-EMISSION; TERMINATION SHOCK; HELIOSPHERE; INTERFACE; SYSTEM AB Results from time-dependent two-dimensional hydrodynamic simulations of the global heliosphere suggest that drag between the plasma ions and the interstellar neutrals, caused by charge-exchange collisions, may cause the heliopause to be hydrodynamically unstable. Both ions and neutrals are treated as fluids coupled by charge-exchange collisions. The neutral-ion drag is proportional to the plasma density and introduces an effective gravity in the direction of the neutral flow, which, because the interstellar plasma is much denser than the heliosheath plasma, causes a Rayleigh-Taylor-like instability to develop. The heliopause Is unstable only near the stagnation point at the ''nose'' of the heliosphere. In the simulations, the heliopause is seen to oscillate nonlinearly about its equilibrium position with a timescale of the order of a hundred years and amplitudes of tens of AUs. Growth rates from the Simulations are in reasonable agreement with theoretical estimates. The possible stabilizing influence of energetic solar wind neutrals, neglected in the present model, is discussed. Implications of this instability on the interpretation of the Voyager 2-3 kHz emissions are also discussed. C1 UNIV CALIF LOS ALAMOS NATL LAB T3,LOS ALAMOS,NM 87545. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Liewer, PC (reprint author), CALTECH,PASADENA,CA 91125, USA. NR 21 TC 63 Z9 63 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1996 VL 101 IS A8 BP 17119 EP 17127 DI 10.1029/96JA00606 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB700 UT WOS:A1996VB70000007 ER PT J AU Krupp, N Tsurutani, BT Lanzerotti, LJ Maclennan, CG AF Krupp, N Tsurutani, BT Lanzerotti, LJ Maclennan, CG TI Low-energy particle oscillations and correlations with hydromagnetic waves in the Jovian magnetosphere: Ulysses measurements SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FREQUENCY GEOMAGNETIC-PULSATIONS; ION-BEAM INSTABILITIES; HOT PLASMA; JUPITER; BEHAVIOR AB We report on measurements of energetic particle modulations (ions and electrons with energies E > 50. keV) observed by the heliosphere instrument for spectra, composition, and anisotropy at low energies (HI-SCALE) aboard the Ulysses spacecraft that were associated with the only hydromagnetic (HM) wave event measured inside the Jovian magnetosphere by the Ulysses magnetometer investigation. This HM-wave event occurred during the high latitude outbound pass of the spacecraft in the dusk sector of the planet at distances between 65 and 68 Jovian radii (R(J)) and at southern magnetic latitudes between 27 degrees and 32 degrees. We show that the approximately 5-min oscillations that occurred for about an hour in the north-south component of the magnetic field are well correlated with variations of the energetic particle fluxes at small pitch angles. The detection of the narrow angle ion beams by the HI-SCALE instrument occurs at the intersection between two angular spin sectors. The small-amplitude waves vary the magnetic field direction sufficiently that the beam is directed primarily toward one sector and then the other, and back again. Possible mechanisms for the HM-wave generation are explained. We show that the HM waves are most likely to be generated by the presence of magnetospheric heavy ions (i.e., sulfur or oxygen) with energies in the range of a few keV. C1 JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD. CALTECH,JET PROP LAB,PASADENA,CA. AT&T BELL LABS,LUCENT TECHNOL,MURRAY HILL,NJ 07974. NR 24 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1996 VL 101 IS A8 BP 17305 EP 17312 DI 10.1029/96JA01296 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB700 UT WOS:A1996VB70000021 ER PT J AU Delcourt, DC Sauvaud, JA Martin, RF Moore, TE AF Delcourt, DC Sauvaud, JA Martin, RF Moore, TE TI On the nonadiabatic precipitation of ions from the near-Earth plasma sheet SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CENTRIFUGAL IMPULSE MODEL; PITCH-ANGLE SCATTERING; MAGNETIC-FIELD MODEL; TAIL CURRENT SHEET; PARTICLE MOTION; AUREOL-3 OBSERVATIONS; NONLINEAR DYNAMICS; MAGNETOTAIL; CONFIGURATION; BOUNDARIES AB We examine the precipitation of ions which result from nonadiabatic pitch angle scattering in the near-Earth magnetotail. We focus on dynamical situations between the adiabatic limit where the particle magnetic moment is conserved and the current sheet limit where particles experience meandering motion about the midplane. Defining the kappa parameter as the square root of the minimum curvature-radius-to-maximum Larmor radius ratio, the situations we consider correspond to kappa between 1 and 3. We demonstrate that throughout this range of kappa values, magnetic moment variations are systematically organized into three categories: (1) at small (a few degrees) equatorial pitch angles, large magnetic moment enhancements regardless of gyration phase; (2) at large equatorial pitch angles (typically, above 30 degrees), negligible magnetic moment changes; and (3) in between, a prominent dependence upon gyration phase with either magnetic moment enhancement or damping. We show that these three distinct regimes can be understood in terms of relative magnitude of the centrifugal force experienced by the particles with regard to that of the Lorentz force. In agreement with previous studies, we show that detrapping of plasma sheet ions due to nonadiabatic pitch angle scattering is effective throughout the 1- to 3-kappa range. However, the degree of loss cone filling critically depends upon the angular characteristics of the incident population. It is significantly greater for initially isotropic populations than for initially field-aligned ones, because only particles away from the magnetic field direction experience strong damping of magnetic moment. C1 ILLINOIS STATE UNIV,DEPT PHYS,NORMAL,IL. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. CTR ETUD SPATIALE RAYONNEMENTS,CNRS,F-31029 TOULOUSE,FRANCE. RP Delcourt, DC (reprint author), CTR ETUD ENVIRONM TERR & PLANETAIRES,CNRS,4 AVE NEPTUNE,F-94107 ST MAUR FOSSES,FRANCE. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 23 TC 76 Z9 76 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1996 VL 101 IS A8 BP 17409 EP 17418 DI 10.1029/96JA01006 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB700 UT WOS:A1996VB70000031 ER PT J AU Ungar, EK Eichhorn, R AF Ungar, EK Eichhorn, R TI Transition boiling curves in saturated pool boiling from horizontal cylinders SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Article ID HEAT-TRANSFER; VELOCITY; FLUX AB Pool boiling heat flux versus wall superheat boiling curves were obtained for horizontal 3.18-mm-dia thin-walled brass tubes heated by an internal high-speed flow of ethylene glycol. The boiling liquids were saturated n-pentane, R-113, acetone, methanol, ethanol, benzene, and isopropanol. Boiling results include nucleate and transition boiling in all the test liquids, but film boiling was achieved only with methanol. The measured peak heat fluxes are well correlated by available predictions. The methanol experiments clearly display two transition boiling curves, one obtained on increasing the cylinder temperature from nucleate boiling, the other on decreasing the cylinder temperature from film boiling. For the cases in which the highest cylinder temperature reached only into the transition regime, a single transition boiling curve resulted. C1 UNIV HOUSTON,CULLEN COLL ENGN,HOUSTON,TX 77204. RP Ungar, EK (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV CREW & THERMAL SYST,HOUSTON,TX 77058, USA. NR 28 TC 7 Z9 8 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-1481 J9 J HEAT TRANS-T ASME JI J. Heat Transf.-Trans. ASME PD AUG PY 1996 VL 118 IS 3 BP 654 EP 661 DI 10.1115/1.2822682 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA VE394 UT WOS:A1996VE39400019 ER PT J AU Vaughan, AH AF Vaughan, AH TI Lens design using group indices of refraction SO JOURNAL OF MODERN OPTICS LA English DT Article AB An approach to lens design is described in which the ratio of the group velocity to the speed of light (the group index) in glass is used, in conjunction with the more familiar phase index of refraction, to control certain chromatic properties of a system of thin lenses in contact. It is shown that, at the wavelength of a maximum or minimum (where the phase power of a lens is locally independent of wavelength), the group power is equal to the phase power. It is further shown that, in a lens consisting of three or more elements, the phase and group powers can be constrained to be both equal and independent of wavelength (achromatic) at one or more wavelengths. In the neighbourhood of such wavelengths, both the first and the second derivatives of phase power with respect to wavelength are zero, giving this type of lens (in principle) an exceptionally high degree of achromatism not previously described, herein called group achromatism. The first-order design of thin-lens systems is illustrated by examples with the help of a computer program incorporating the methods described. RP Vaughan, AH (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 2 Z9 2 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0950-0340 J9 J MOD OPTIC JI J. Mod. Opt. PD AUG PY 1996 VL 43 IS 8 BP 1683 EP 1700 PG 18 WC Optics SC Optics GA VA529 UT WOS:A1996VA52900015 ER PT J AU Hojer, S May, RD AF Hojer, S May, RD TI Air-broadening coefficients for the nu(3) band of CF4 SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID RESOLUTION INFRARED-SPECTROSCOPY; DOUBLE-RESONANCE; INTENSITIES; PARAMETERS; TRENDS; C2F6; HNO3 AB Air-broadening coefficients for the 1283 cm(-1), nu(3), band of carbon tetrafluoride, CF4, have been measured over the temperature range 217-296 K using a tunable diode laser spectrometer. The dependence of the broadening coefficients on temperature and rotation has been investigated in order to improve analyses of atmospheric spectra. An average air-broadening coefficient at 296 K was determined to be 0.078 (+/-0.005) cm(-1)/atm when averaged over all R(J) manifolds studied. The temperature dependence of the air-broadening coefficient, n, was also measured from the spectra and found to be in the range n=0.64-0.69 from examination of spectra recorded at temperatures of 220, 250, and 296 K. The dependence of the broadening coefficients on the rotational quantum number, J, is also discussed. (C) 1996 Academic Press, Inc. RP Hojer, S (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 18 TC 5 Z9 5 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD AUG PY 1996 VL 178 IS 2 BP 139 EP 142 DI 10.1006/jmsp.1996.0167 PG 4 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA VC703 UT WOS:A1996VC70300001 ER PT J AU Angel, PW DeGuire, MR Cooper, AR AF Angel, PW DeGuire, MR Cooper, AR TI Electrical conductivity, relaxation and the glass transition: A new look at a familiar phenomenon SO JOURNAL OF NON-CRYSTALLINE SOLIDS LA English DT Article; Proceedings Paper CT 13th University Conference on Glass Science - Optical and Electrical Properties of Glasses CY AUG 09-11, 1995 CL RENSSELAER POLYTECH INST, TROY, NY SP Amer Ceram Soc, Asahi Glass Fdn, Corning Inc, Heraeus Amersil Inc, Hoya Corp, Natl Sci Fdn, Nippon Elect Glass Co, Nippon Sheet Glass Co, USN, Off Naval Res, Schott Glass Technol Inc HO RENSSELAER POLYTECH INST ID THERMAL HISTORY AB Annealed samples from a single melt of a 10 mol% K2O-90SiO(2) glass were reheated to temperatures ranging from 450 to 800 degrees C, held isothermally for 20 min, and then quenched in either air or a silicone oil bath. The complex impedance of both the annealed and quenched samples was measured as a function of temperature from 120 to 250 degrees C using ac impedance spectroscopy from 1 Hz to 1 MHz. The de conductivity, sigma(dc), was measured from the low frequency intercept of depressed semicircle fits to the complex impedance data. When the sigma(dc) at 150 degrees C was plotted against soak temperature, the results fell into three primary regions that are explained in terms of the glass structural relaxation time, tau(s). This sigma(dc) plot provides a new way to look at the glass transformation range, Delta T-r. In addition, sigma(dc) was measured for different soak times at 550 degrees C, from which an average relaxation time of 7.3 min was calculated. It was found that the size and position of the Delta T-r is controlled by both the soak time and cooling rate. C1 CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106. RP Angel, PW (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 20 TC 2 Z9 2 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-3093 J9 J NON-CRYST SOLIDS JI J. Non-Cryst. Solids PD AUG PY 1996 VL 203 BP 286 EP 292 DI 10.1016/0022-3093(96)00360-2 PG 7 WC Materials Science, Ceramics; Materials Science, Multidisciplinary SC Materials Science GA VL859 UT WOS:A1996VL85900044 ER PT J AU Putcha, L Tietze, KJ Bourne, DWA Parise, CM Hunter, RP Cintron, NM AF Putcha, L Tietze, KJ Bourne, DWA Parise, CM Hunter, RP Cintron, NM TI Bioavailability of intranasal scopolamine in normal subjects SO JOURNAL OF PHARMACEUTICAL SCIENCES LA English DT Article ID MOTION-SICKNESS; TRANSDERMAL SCOPOLAMINE; PREVENTION; EFFICACY; PLASMA; HUMANS AB The bioavailability of scopolamine in three dosage forms was compared in 12 healthy nonsmoking male volunteers. Subjects received 0.4-mg doses of scopolamine bromide in intravenous (IV), intranasal (IN), or oral (PO) dosage forms on three occasions, with at least 2 weeks separating the doses. Scopolamine concentrations in plasma were determined with a combined reverse-phase liquid chromatographic-radioreceptor binding assay. Saliva volume and flow rate and percent suppression of control flow rate were determined from each sample. Absorption after IN and PO scopolamine administration was rapid; plasma concentrations [1680 (IN) and 164 pg/mL (PO)] peaked within 1 h of dosing [0.37 (IN) and 0.78 h (PO)], respectively. IN and IV scopolamine suppressed salivary flow rate to similar extents (95% and 99.7%), respectively. Times to reach maximum effect were 1.05 and 0.27 h after IN and IV dosage, respectively. Absolute intranasal bioavailability, calculated from the area under the drug concentration vs time curve, was found to be significantly greater than that of PO scopolamine (83% vs 3.7%, p < 0.05). The IN route may provide a noninvasive, reliable, fast, and effective route for administering scopolamine. C1 UNIV OKLAHOMA,COLL PHARM,OKLAHOMA CITY,OK 73117. PHILADELPHIA COLL PHARM & SCI,PHILADELPHIA,PA 19104. RP Putcha, L (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,HOUSTON,TX 77058, USA. RI Hunter, Robert/A-2306-2008 OI Hunter, Robert/0000-0003-1224-2376 NR 22 TC 15 Z9 15 U1 0 U2 4 PU AMER PHARMACEUTICAL ASSN PI WASHINGTON PA 2215 CONSTITUTION AVE NW, WASHINGTON, DC 20037 SN 0022-3549 J9 J PHARM SCI JI J. Pharm. Sci. PD AUG PY 1996 VL 85 IS 8 BP 899 EP 902 DI 10.1021/js950327b PG 4 WC Chemistry, Medicinal; Chemistry, Multidisciplinary; Pharmacology & Pharmacy SC Pharmacology & Pharmacy; Chemistry GA VC084 UT WOS:A1996VC08400023 PM 8863287 ER PT J AU VazquezCuervo, J Font, J MartinezBenjamin, JJ AF VazquezCuervo, J Font, J MartinezBenjamin, JJ TI Observations on the circulation in the Alboran Sea using ERS1 altimetry and sea surface temperature data SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID CAPE-HATTERAS; GULF-STREAM AB Data from the altimeter onboard the European Remote Sensing Satellite (ERS1) was used to study the circulation of the Alboran Sea between 35 degrees and 38 degrees N, 0 degrees and 6 degrees W. This region is dominated by two anticyclonic gyres that are quasi-stationary in space but at times collapse over periods as short as 9 days. Maps of sea level residual, between February 1992 and December 1993, were created from the ERS1 data with high correlation between sea surface temperature and residual sea level in the eastern part of the Alboran Sea. The spatially coherent signal was then extracted using the technique of complex empirical orthogonal analysis with the first three modes statistically significant. The variability of the first complex empirical orthogonal function mode appears to be associated with the incoming jet through the straits of Gibraltar with three time periods of high amplitude during the 1992-93 time frame. The second and third modes appear to be associated with the variability of both the western and eastern gyres. Westward propagation in the third mode is evident in the area of the eastern anticyclonic gyre and consistent with previous model simulations. The results indicate that combining sea surface temperature data and sea level data from altimetry holds promise for understanding the circulation of the Western Mediterranean. C1 UNIV AUTONOMA BARCELONA, CSIC, INST CIENCIAS MAR, E-08193 BARCELONA, SPAIN. UNIV POLITECN CATALUNYA, DEPT FIS APLICADA, BARCELONA, SPAIN. RP VazquezCuervo, J (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, M-S 300-323, PASADENA, CA 91109 USA. RI Font, Jordi/E-5355-2013 OI Font, Jordi/0000-0003-2590-1457 NR 28 TC 21 Z9 21 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD AUG PY 1996 VL 26 IS 8 BP 1426 EP 1439 DI 10.1175/1520-0485(1996)026<1426:OOTCIT>2.0.CO;2 PG 14 WC Oceanography SC Oceanography GA VE369 UT WOS:A1996VE36900003 ER PT J AU Hergenrother, PM AF Hergenrother, PM TI Aromatic polypyromellitimides from aromatic polyamic acids - Comments SO JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY LA English DT Editorial Material RP Hergenrother, PM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 1 U2 4 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-624X J9 J POLYM SCI POL CHEM JI J. Polym. Sci. Pol. Chem. PD AUG PY 1996 VL 34 IS 11 BP 2067 EP 2068 DI 10.1002/pola.1996.845 PG 2 WC Polymer Science SC Polymer Science GA UX705 UT WOS:A1996UX70500003 ER PT J AU Brown, LR Plymate, C AF Brown, LR Plymate, C TI H-2-broadened (H2O)-O-16 in four infrared bands between 55 and 4045 cm(-1) SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID WATER-VAPOR LINES; NITRIC-OXIDE; PARAMETERS AB To support the remote sensing of the outer planets, absorption spectra of H2O broadened by H-2 were recorded at room temperature using two Fourier transform spectrometers. The data from 1260 to 2070 cm(-1) and 3420 to 4045 cm(-1) were obtained at 0.0056 and 0.012 cm(-1) resolution (unapodized), respectively, with the McMath FTS located at Kitt Peak National Observatory/National Solar Observatory. The remainder of the spectral data from 55 to 328 cm(-1) was taken at 0.0056 cm(-1) with the HR120 Bruker FTS at the Jet Propulsion Laboratory. Some 630 H-2-broadened linewidths of (H2O)-O-16 were obtained with precisions of 2-7% for the four strongest water bands: rotational at 0 cm(-1); nu(2) at 1595 cm(-1); nu(1) at 3657 cm(-1) and nu(3) at 3756 cm(-1). The intensity of the weakest measured transition was 0.0065 cm(-2)/atm at room temperature. Within a band, the widths varied from 0.101 to 0.033 cm(-1)/atm at room temperature for 0 less than or equal to J less than or equal to 12 and 0 less than or equal to Ka less than or equal to 6. Systematic patterns were detected in the widths as a function of Delta J, J, Ka, and asymmetry. At low Ka, the widths decreased with increasing J, but for Ka > 2, the widths generally increased with increasing J. Examination of the vibrational dependencies of the three perpendicular bands also revealed that the widths of the nu(2) and rotational transitions were nearly the same (within 3%), but the widths of nu(1) were generally larger (up to 18%). The limited width measurements reported by others in the pure rotational and 1.4 mu m regions supported the conclusions concerning vibrational dependencies. Copyright (C) 1996 Elsevier Science Ltd. C1 NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,TUCSON,AZ 85726. RP Brown, LR (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 38 Z9 39 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD AUG PY 1996 VL 56 IS 2 BP 263 EP 282 DI 10.1016/0022-4073(95)00191-3 PG 20 WC Optics; Spectroscopy SC Optics; Spectroscopy GA VD019 UT WOS:A1996VD01900008 ER PT J AU Brown, LR Margolis, JS AF Brown, LR Margolis, JS TI Empirical line parameters of NH3 from 4791 to 5294 cm(-1) SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID SPECTRUM; BANDS; INTENSITIES; STRENGTHS; AMMONIA AB To support remote sensing of planetary atmospheres at 2 mu m, laboratory spectra of NH3 and enriched (NH3)-N-14 and (NH3)-N-15 were recorded at 0.011 cm(-1) resolution with the McMath Fourier transform spectrometer (FTS) located at Kitt Peak National Observatory/National Solar Observatory. Multiple optical paths and pressures were used with sample temperatures between 297 and 185 K. Some 2000 line positions and intensities at room temperature were measured with precisions of 0.0003 cm(-1) and 3%, respectively, for unblended transitions. Low and room temperature intensities were then combined to determine empirical lower state energies for 1815 lines. These data permitted the assignments for nu(1) + nu(4) of (NH3)-N-14 to be extended to J' = 10. Transitions of nu(3) + nu(4) of (NH3)-N-15 were also cataloged for the first time. Nearly 45% of the 2000 measured features were identified, and empirical upper state levels were obtained. The experimental results for lines with measured intensities greater than 3 x 10(-24) cm(-1)/(molecule . cm(-2)) at 296 K were included in the 1996 HITRAN database. To obtain consistent NH3 line positions, the positions of 28 H2O transitions between 5206 and 5396 cm(-1) were also calibrated using the 2-0 band of CO at 4260 cm(-1). Copyright (C) 1996 Elsevier Science Ltd. RP Brown, LR (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 31 Z9 31 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD AUG PY 1996 VL 56 IS 2 BP 283 EP 294 DI 10.1016/0022-4073(96)00041-6 PG 12 WC Optics; Spectroscopy SC Optics; Spectroscopy GA VD019 UT WOS:A1996VD01900009 ER PT J AU Park, K Nolt, IG Steele, TC Zink, LR Evenson, KM Chance, KV Murray, AG AF Park, K Nolt, IG Steele, TC Zink, LR Evenson, KM Chance, KV Murray, AG TI Pressure broadening of the 50.873 and 83.469 cm(-1) molecular oxygen lines SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID N2; O2 AB We report pressure broadening measurements of the 50.873 and 83.469 cm(-1) molecular oxygen lines at 293 K. Air broadening coefficients are determined with 13% accuracy. Published by Elsevier Science Ltd. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NATL INST STAND & TECHNOL,BOULDER,CO 80303. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV LONDON QUEEN MARY & WESTFIELD COLL,LONDON E1 4NS,ENGLAND. RP Park, K (reprint author), UNIV OREGON,DEPT PHYS,EUGENE,OR 97403, USA. OI Chance, Kelly/0000-0002-7339-7577 NR 8 TC 10 Z9 10 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD AUG PY 1996 VL 56 IS 2 BP 315 EP 316 DI 10.1016/0022-4073(96)00026-X PG 2 WC Optics; Spectroscopy SC Optics; Spectroscopy GA VD019 UT WOS:A1996VD01900013 ER PT J AU Pearson, JB Landrum, DB Hawk, CW AF Pearson, JB Landrum, DB Hawk, CW TI Parametric study of solar thermal rocket nozzle performance SO JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article C1 UNIV ALABAMA,PROPULS RES CTR,HUNTSVILLE,AL 35899. RP Pearson, JB (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,THERMAL ENGN & DESIGN BRANCH,HUNTSVILLE,AL 35812, USA. NR 4 TC 0 Z9 0 U1 3 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0199-6231 J9 J SOL ENERG-T ASME JI J. Sol. Energy Eng. Trans.-ASME PD AUG PY 1996 VL 118 IS 3 BP 194 EP 195 DI 10.1115/1.2870944 PG 2 WC Energy & Fuels; Engineering, Mechanical SC Energy & Fuels; Engineering GA VD785 UT WOS:A1996VD78500010 ER PT J AU Lopez, AM Junkin, B McGregor, L AF Lopez, AM Junkin, B McGregor, L TI Gross feature detection in remotely sensed CAMS imagery using a multi-paradigm software approach SO JOURNAL OF SYSTEMS AND SOFTWARE LA English DT Article ID INFORMATION AB Rules used to classify regions in images that have been remotely sensed from airborne or satellite platforms are not universal truths even for gross feature detection (i.e., trees, man-made objects, water, etc.). The classification of each pixel in a data set obtained from an aerial or satellite image can be a difficult and time-consuming process for both a computer and a human. Consequently, throughout the National Aeronautics and Space Administration (NASA) information systems researchers are seeking innovative approaches that will assist human experts in the time-consuming endeavor of classifying remotely sensed data. This article reports on a study, commissioned by the director of NASA's John C. Stennis Space Center (SSC) in Mississippi, to investigate the use of Artificial Intelligence (Al) techniques in the classification of remotely sensed data collected using the Calibrated Airborne Multispectral Scanner (CAMS). The study resulted in the development of a proof-of-concept software system that takes a multi-paradigm software approach to gross feature detection in remotely sensed CAMS data. C1 JOHN C STENNIS SPACE CTR,NASA,INFORMAT SYST DIV,SCI & TECHNOL LAB,STENNIS,MS. JOHN C STENNIS SPACE CTR,SVERDRUP TECHNOL INC,STENNIS,MS. RP Lopez, AM (reprint author), LOYOLA UNIV,BOX 51,NEW ORLEANS,LA 70118, USA. NR 13 TC 0 Z9 0 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0164-1212 J9 J SYST SOFTWARE JI J. Syst. Softw. PD AUG PY 1996 VL 34 IS 2 BP 151 EP 159 DI 10.1016/0164-1212(96)00050-7 PG 9 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA UV222 UT WOS:A1996UV22200007 ER PT J AU Jacobson, NS Lee, KN Yoshio, T AF Jacobson, NS Lee, KN Yoshio, T TI Corrosion of mullite by molten salts SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID SIC CERAMICS; COATINGS AB The interaction of molten salts of different Na2O activities and mullite is examined with furnace and burner tests. The more-acidic molten salts form small amounts of Al2O3; the more-basic molten salts form various Na2O-Al2O3-SiO2 compounds. The results are interpreted using the Na2O-Al2O3-SiO2 ternary phase diagram, and some possible diffusion paths are discussed. The generally higher melting points of Na2O-Al2O3-SiO2 compounds lead to better behavior of mullite in molten salts, as compared to SiO2-protected ceramics such as SIC. Mullite-coated SIC is discussed, and the corrosion behavior is evaluated. C1 OKAYAMA UNIV,OKAYAMA 700,JAPAN. RP Jacobson, NS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Jacobson, Nathan/A-9411-2009 NR 21 TC 31 Z9 31 U1 0 U2 6 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD AUG PY 1996 VL 79 IS 8 BP 2161 EP 2167 DI 10.1111/j.1151-2916.1996.tb08951.x PG 7 WC Materials Science, Ceramics SC Materials Science GA VC613 UT WOS:A1996VC61300023 ER PT J AU Ratnakumar, BV Witham, C Bowman, RC Hightower, A Fultz, B AF Ratnakumar, BV Witham, C Bowman, RC Hightower, A Fultz, B TI Electrochemical studies on LaNi5-xSnx metal hydride alloys SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID HYDROGEN BATTERIES; NICKEL-HYDROGEN; ELECTRODES; LANI5-YSNY; STORAGE AB Electrochemical studies mere performed on LaNi5-xSnx with 0 less than or equal to x less than or equal to 0.5. We measured the effect of the Sn substituent on the kinetics of charge-transfer and diffusion during hydrogen absorption and desorption, and the cyclic lifetimes of LaNi5-xSx electrodes in 250 mAh laboratory test cells. We report beneficial effects of making small substitutions of Sn for Ni in LaNi, on the performance of the metal hydride alloy anode in terms of cyclic lifetime, capacity, and kinetics. The optimal concentration of Sn in LaNi5-xSnx alloys for negative electrodes in alkaline rechargeable secondary cells was found to lie in the range 0.25 less than or equal to x less than or equal to 0.3. C1 CALTECH,DIV ENGN & APPL SCI,PASADENA,CA 91125. RP Ratnakumar, BV (reprint author), CALTECH,JET PROP LAB,ELECTROCHEM TECHNOL GRP,PASADENA,CA 91109, USA. OI Bowman, Robert/0000-0002-2114-1713 NR 32 TC 155 Z9 164 U1 1 U2 17 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 10 SOUTH MAIN STREET, PENNINGTON, NJ 08534 SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD AUG PY 1996 VL 143 IS 8 BP 2578 EP 2584 DI 10.1149/1.1837050 PG 7 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA VC706 UT WOS:A1996VC70600036 ER PT J AU Lim, HS Han, DS AF Lim, HS Han, DS TI An approach to remedy beam filling error of TMI by the use of VIRS measurements SO JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN LA English DT Article ID MULTICHANNEL MICROWAVE RADIOMETER; EL-NINO; RAINFALL; OCEANS; GATE; SMMR AB The beam filling error is a significant problem in rain rate retrieval from passive microwave radiometer measurements from space. Rain will not be uniformly distributed throughout footprints of the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI). This inhomogeneous rainfall distribution within the field of view (FOV) and non-linear relationship of rain rates and brightness temperature (R-T) produces errors. This error can be reduced if we have some information on rain/no-rain at a higher spatial resolution. The Visible IR Scanner (VIRS) on the TRMM observatory will provide cloud coverage, type and cloud top temperature at high resolution (2 km at nadir). In this study, we have examined how good the rain/no-rain criteria should be from VIRS in order to improve TMI rain retrievals using a simple passive microwave rain retrieval algorithm. It is found that the improvement in rain retrieval using VIRS rain/no-rain information depends on the intensity of rain rates. Generally, it is better to overestimate raining fractions of moderate and heavy rain within a footprint than underestimate them. On the other hand, it is better to underestimate raining fractions of light rain than overestimate them. We can have improvements of rain retrievals by the TMI in heavy rainfall (r greater than or equal to 20 mm hr(-1)) with the aid of VIRS measurements when scattering effects are considered. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NR 21 TC 0 Z9 0 U1 0 U2 1 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 AUG PY 1996 VL 74 IS 4 BP 415 EP 423 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA VH803 UT WOS:A1996VH80300003 ER PT J AU Yao, XS Maleki, L AF Yao, XS Maleki, L TI Optoelectronic microwave oscillator SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article ID COMPONENTS; FEEDBACK; DEVICES; LASERS AB We describe a novel oscillator that converts continuous light energy into stable and spectrally pure microwave signals. This optoelectronic microwave oscillator consists of. pump laser and a feedback circuit including an intensity modulator, an optical fiber delay line, a photodetector, an amplifier, and a filter. We develop a quasi linear theory and obtain expressions for the threshold condition, the amplitude, the frequency, the line width, and the spectral power density of the oscillation. We also present experimental data to compare with the theoretical results. Our findings indicate that the optoelectronic microwave oscillator can generate ultrastable, spectrally pure microwave reference signals up to 75 GHz with a phase noise lower than - 140 dBc/Hz at 10 kHz. (C) 1996 Optical Society of America. RP CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 39 TC 427 Z9 457 U1 3 U2 35 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0740-3224 EI 1520-8540 J9 J OPT SOC AM B JI J. Opt. Soc. Am. B-Opt. Phys. PD AUG PY 1996 VL 13 IS 8 BP 1725 EP 1735 DI 10.1364/JOSAB.13.001725 PG 11 WC Optics SC Optics GA VA929 UT WOS:A1996VA92900011 ER PT J AU Laskowski, JA Dellacorte, C AF Laskowski, JA Dellacorte, C TI Friction and wear characteristics of candidate foil bearing materials from 25 degrees C to 800 degrees C SO LUBRICATION ENGINEERING LA English DT Article DE unlubricated wear; unlubricated friction; adverse environments tribology ID JOURNAL BEARINGS AB The friction and wear behavior of unlubricated metal/metal sliding couples was investigated to screen potential candidates for high-temperature foil bearings. The tribo-tests were run in an induction-heated high-temperature pin-on-disk tribometer in an air atmosphere at a load of 4.9 N and at a sliding velocity of 1 m/s. The friction and wear properties of several nickel-based alloys (Rene 41, Inconel X-750, Inconel 713C), iron-based alloys (MA956 and Inconel 909) and a ceramic (Al2O3) were tested at 25 degrees, 500 degrees, and 800 degrees C. In general, the alloys oxidized at elevated temperatures and formed a tenacious and lubricous oxide surface film or layer. At 800 degrees C, Inconel X-750 vs. Rene 41 had the lowest friction coefficient (0.27) and, at 500 degrees C, Inconel X-750 vs. Inconel 909 the lowest pin wear (2.84 X 10(-6) mm(3)/N-m). Gouging and severe wear of the softer material occurred whenever a significant difference in hardness existed between the pin and disk specimens. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. ST LOUIS UNIV,PARKS COLL,CAHOKIA,IL 62206. NR 18 TC 10 Z9 10 U1 1 U2 3 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD AUG PY 1996 VL 52 IS 8 BP 605 EP 612 PG 8 WC Engineering, Mechanical SC Engineering GA VC436 UT WOS:A1996VC43600002 ER PT J AU Whittenberger, JD Noebe, RD AF Whittenberger, JD Noebe, RD TI Strength loss in NiAl+Zr alloys at 1200 K SO MATERIALS LETTERS LA English DT Article DE intermetallic; NiAl; NiAl + Zr; high temperature strength; creep; annealing ID SLOW PLASTIC-FLOW; 1100-K; 1400-K AB During compression testing of NiA1 + Zr alloys at 1200 K and a strain rate of 2.1 x 10(-5) s(-1), strength was found to depend on time at temperature prior to testing. The observed strength loss appears to provide additional evidence that creep in Zr-modified NiAl is controlled by Zr atmospheres surrounding gliding dislocations. C1 MAX PLANCK INST MET RES,STUTTGART,GERMANY. RP Whittenberger, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 14 TC 2 Z9 2 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-577X J9 MATER LETT JI Mater. Lett. PD AUG PY 1996 VL 27 IS 6 BP 281 EP 286 DI 10.1016/0167-577X(96)00012-2 PG 6 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA VB356 UT WOS:A1996VB35600002 ER PT J AU Tipton, CM Hargens, A AF Tipton, CM Hargens, A TI Physiological adaptations and countermeasures associated with long-duration spaceflights SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Editorial Material DE long-term spaceflights; countermeasures; space history AB Since 1961, there have been more than 165 flights involving several hundred individuals who have remained in a space environment from 15 min to more than a year. In addition, plans exist for humans to explore, colonize, and remain in microgravity for 1000 d or more. This symposium will address the current state of knowledge in select aspects associated with the cardiovascular, fluid and electrolytes, musculoskeletal, and the neuroendocrine and immune systems. The authors will focus on responses, mechanisms, and the appropriate countermeasures to minimize or prevent the physiological and biochemical consequences of a microgravity environment. Since exercise is frequently cited as a generic countermeasure, this topic will be covered in greater detail. Models for simulated microgravity conditions will be discussed in subsequent manuscripts, as will future directions for ground-based research. C1 NASA,AMES RES CTR,GRAVITAT RES BRANCH,MOFFETT FIELD,CA 94035. RP Tipton, CM (reprint author), UNIV ARIZONA,DEPT PHYSIOL,INA GITTINGS BLDG,ROOM 24A,TUCSON,AZ 85721, USA. NR 4 TC 5 Z9 5 U1 0 U2 2 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD AUG PY 1996 VL 28 IS 8 BP 974 EP 976 DI 10.1097/00005768-199608000-00006 PG 3 WC Sport Sciences SC Sport Sciences GA VC749 UT WOS:A1996VC74900006 PM 8871906 ER PT J AU Hargens, AR Watenpaugh, DE AF Hargens, AR Watenpaugh, DE TI Cardiovascular adaptation to spaceflight SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Article DE human; microgravity; weightlessness; gravitational blood pressures; microcirculation; countermeasures ID BODY NEGATIVE-PRESSURE; SHORT-DURATION SPACEFLIGHT; CENTRAL VENOUS-PRESSURE; SPACE-FLIGHT; ORTHOSTATIC INTOLERANCE; FLUID SHIFTS; BED REST; WEIGHTLESSNESS; RESPONSES; COUNTERMEASURE AB This article reviews recent flight and ground-based studies of cardiovascular adaptation to spaceflight. Prominent features of microgravity exposure include loss of gravitational pressures, relatively low venous pressures, headward fluid shifts, plasma volume loss, and postflight orthostatic intolerance and reduced exercise capacity. Many of these short-term responses to microgravity extend themselves during long-duration microgravity exposure and may be explained by altered pressures (blood and tissue) and fluid balance in local tissues nourished by the cardiovascular system. In this regard, it is particularly noteworthy that tissues of the lower body (e.g., foot) are well adapted to local hypertension on Earth, whereas tissues of the upper body (e.g., head) are not as well adapted to increases in local blood pressure. For these and other reasons, countermeasures for long-duration flight should include reestablishment of higher, Earth-like blood pressures in the lower body. RP Hargens, AR (reprint author), NASA,AMES RES CTR,GRAVITAT RES BRANCH,LIFE SCI DIV 239 11,MOFFETT FIELD,CA 94035, USA. NR 56 TC 80 Z9 84 U1 5 U2 12 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD AUG PY 1996 VL 28 IS 8 BP 977 EP 982 DI 10.1097/00005768-199608000-00007 PG 6 WC Sport Sciences SC Sport Sciences GA VC749 UT WOS:A1996VC74900007 PM 8871907 ER PT J AU Tipton, CM Greenleaf, JE Jackson, CGR AF Tipton, CM Greenleaf, JE Jackson, CGR TI Neuroendocrine and immune system responses with spaceflights SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Article DE space flight; microgravity; neuroendocrine changes; immune responses; head-down tilt; bed rest ID GROWTH-HORMONE; BED REST; SKELETAL-MUSCLE; EXERCISE; RATS; MICROGRAVITY; LYMPHOCYTES; PRESSURE; ATROPHY; SPACE AB Despite the fact that the first human was in space during 1961 and individuals have existed in a microgravity environment for more than a year, there are limited spaceflight data available on the responses of the neuroendocrine and immune systems. Because of mutual interactions between these respective integrative systems, it is inappropriate to assume that the responses of one have no impact on functions of the other. Blood and plasma volume consistently decrease with spaceflight; hence, blood endocrine and immune constituents will be modified by both gravitational and measurement influences. The majority of the in-flight data relates to endocrine responses that influence fluids and electrolytes during the first month in space. Adrenocorticotropin (ACTH), aldosterone, and anti-diuretic hormone (ADH) appear to be elevated with little change in the atrial natriuretic peptides (ANP). Flight results longer than 60 d show increased ADH variability with elevations in angiotensin and cortisol. Although post-flight results are influenced by reentry and recovery events, ACTH and ADH appear to be consistently elevated with variable results being reported for the other hormones. Limited in-flight data on insulin and growth hormone levels suggest they are not elevated to counteract the loss in muscle mass. Post-flight results from short- and long-term flights indicate that thyroxine and insulin are increased while growth hormone exhibits minimal change. In-flight parathyroid hormone (PTH) levels are variable for several weeks after which they remain elevated. Post-flight PTH was increased on missions that lasted either 7 or 237 d, whereas calcitonin concentrations were increased after 1 wk but decreased after longer flights. Leukocytes are elevated in flights of various durations because of an increase in neutrophils. The majority of post-flight data indicates immunoglobulin concentrations are not significantly changed from pre-flight measurements. However, the numbers of T-lymphocytes and natural killer cells are decreased with post-flight conditions. Of the lymphokines, interleukin-2 production, lymphocyte responsiveness, and the activity of natural killer cells are consistently reduced post-flight. Limited head-down tilt (HDT) data suggest it is an effective simulation model for microgravity investigations. Neuroendocrine and pharmacological countermeasures are virtually nonexistent and should become high priority items for future research. Although exercise has the potential to be an effective countermeasure for various neuroendocrine-immune responses in microgravity, this concept must be tested before flights to Mars are scheduled. C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. UNIV NO COLORADO,SCH KINESIOL & PHYS EDUC,GREELEY,CO 80631. RP Tipton, CM (reprint author), UNIV ARIZONA,DEPT PHYSIOL,GITTINGS BLDG,TUCSON,AZ 85721, USA. NR 79 TC 46 Z9 48 U1 1 U2 8 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD AUG PY 1996 VL 28 IS 8 BP 988 EP 998 DI 10.1097/00005768-199608000-00009 PG 11 WC Sport Sciences SC Sport Sciences GA VC749 UT WOS:A1996VC74900009 PM 8871909 ER PT J AU Dessenne, CAC Green, DA Warner, PJ Titterington, DJ Waldram, EM Barthelmy, SD Butterworth, PS Cline, TL Gehrels, N Palmer, DM Fishman, GJ Kouveliotou, C Meegan, CA AF Dessenne, CAC Green, DA Warner, PJ Titterington, DJ Waldram, EM Barthelmy, SD Butterworth, PS Cline, TL Gehrels, N Palmer, DM Fishman, GJ Kouveliotou, C Meegan, CA TI Searches for prompt radio emission at 151 MHz from the gamma-ray bursts GRB 950430 and GRB 950706 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE instrumentation, miscellaneous; gamma-rays, bursts; radio continuum, general ID COUNTERPART AB The Cambridge Low Frequency Synthesis Telescope (CLFST) has been used to search for prompt radio emission at 151 MHz from gamma-ray bursts (GRBs) detected by the Burst And Transient Source Experiment (BATSE) aboard the Compton Gamma-Ray Observatory, The CLFST was reconfigured so that it can reach similar to 10 per cent of the sky in 1.5 min. The real-time follow-up observations of GRB 950430 and GRB 950706 presented here provide deep upper limits on the flux density of any radio pulse matching the GRB duration, For GRB 950430 the (3 sigma) limits are 73 Jy for the period from 280 min before to 6 min after the burst, and 35 Jy for the period 6 to 145 min after the burst, For GRB 950706 the limit is 16 Jy for the period 16 to 60 min after the burst, Assuming a thermal radio spectrum, our limits for the period 6 to 145 min following GRB 950430 yield an upper limit of similar to 3 x 10(-4) for the ratio of the radio to the gamma-ray luminosity of this burst, In addition we have looked for variable sources in the field of GRB 950430 for the 3 h following the GRB: no new source with a flux density above 1 Jy was found. C1 UNIV CAMBRIDGE,CAVENDISH LAB,MULLARD RADIO ASTRON OBSERV,CAMBRIDGE CB3 0HE,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35899. RI Gehrels, Neil/D-2971-2012; Green, David/E-9609-2010; Barthelmy, Scott/D-2943-2012 OI Green, David/0000-0003-3189-9998; NR 18 TC 17 Z9 17 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD AUG 1 PY 1996 VL 281 IS 3 BP 977 EP 984 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB271 UT WOS:A1996VB27100026 ER PT J AU Christian, H AF Christian, H TI Optical sensor may provide earlier warning of tornadoes SO PHOTONICS SPECTRA LA English DT Article RP Christian, H (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LAURIN PUBL CO INC PI PITTSFIELD PA BERKSHIRE COMMON PO BOX 1146, PITTSFIELD, MA 01202 SN 0731-1230 J9 PHOTON SPECTRA JI Photon. Spect. PD AUG PY 1996 VL 30 IS 8 BP 92 EP 93 PG 2 WC Optics SC Optics GA VB784 UT WOS:A1996VB78400030 ER PT J AU Hegseth, JJ Rashidnia, N Chai, A AF Hegseth, JJ Rashidnia, N Chai, A TI Natural convection in droplet evaporation SO PHYSICAL REVIEW E LA English DT Article AB Although droplet evaporation is widely assumed to be a diffusion process, our results shaw that when a droplet evaporates sufficiently fast it exhibits a vigorous interior how. This flow is driven by surface ter sion gradients. The typical interior flow field behavior is shown as well as measurements of the droplet surface area and volume as it evaporates. We also discuss the droplet lifetime and how the system tends toward a state of marginal stability. C1 NASA,LEWIS RES CTR,SPACE EXPT DIV,CLEVELAND,OH 44135. RP Hegseth, JJ (reprint author), UNIV NEW ORLEANS,DEPT PHYS,NEW ORLEANS,LA 70148, USA. NR 12 TC 63 Z9 63 U1 0 U2 6 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 AUG PY 1996 VL 54 IS 2 BP 1640 EP 1644 DI 10.1103/PhysRevE.54.1640 PG 5 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA VD674 UT WOS:A1996VD67400084 ER PT J AU Mahalov, A Zhou, Y AF Mahalov, A Zhou, Y TI Analytical and phenomenological studies of rotating turbulence SO PHYSICS OF FLUIDS LA English DT Article ID ISOTROPIC TURBULENCE; INERTIAL-RANGE; HOMOGENEOUS TURBULENCE; RENORMALIZATION-GROUP; ENERGY-TRANSFER; STRESS MODELS; WAVES AB A framework, which combines mathematical analysis, closure theory, and phenomenological treatment, is developed to study the spectral transfer process in turbulent flows that are subject to rotation. First, we outline a mathematical procedure that is particularly appropriate for problems with two disparate time scales. The approach that is based on the Green's method leads to the Poincare velocity variables and the Poincare transformation when applied to rotating turbulence. The effects of the rotation are now conveniently included in the momentum equation as the modifications to the convolution of nonlinear term. The Poincare transformed equations are used to obtain a time-dependent Taylor-Proudman theorem valid in the asymptotic limit when the nondimensional parameter mu = Omega t --> infinity (Omega is the rotation rate and t is the time). The ''split'' of the energy transfer in both direct and inverse directions is established. Second, we apply the Eddy-Damped-Quasinormal-Markovian (EDQNM) closure to the Poincare transformed Euler/Navier-Stokes equations. This closure leads to expressions for the spectral energy transfer. In particular, a unique triple velocity decorrelation time is derived with an explicit dependence on the rotation rate. This provides an important input for applying the phenomenological treatment of Zhou [Phys. Fluids 7, 2092 (1995)]. In order to characterize the relative strength of rotation, another nondimensional number, a spectral Rossby number, which is defined as the ratio of rotation, and turbulence time scales, is introduced. Finally, the energy spectrum and the spectral eddy viscosity are deduced. (C) 1996 American Institute of Physics. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. RP Mahalov, A (reprint author), ARIZONA STATE UNIV,DEPT MATH,TEMPE,AZ 85287, USA. NR 43 TC 24 Z9 25 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD AUG PY 1996 VL 8 IS 8 BP 2138 EP 2152 DI 10.1063/1.868988 PG 15 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA UX897 UT WOS:A1996UX89700016 ER PT J AU McKay, CP AF McKay, CP TI Elemental composition, solubility, and optical properties of Titan's organic haze SO PLANETARY AND SPACE SCIENCE LA English DT Article ID ATMOSPHERE; AEROSOLS; PHOTOCHEMISTRY; TEMPERATURE; CHEMISTRY; MODEL AB It is found that solid;organic material produced by electrical discharge in a simulated Titan atmosphere (10% CH4 90% N-2) has an elemental composition corresponding to C11H11N2. Immersion in liquid ethane followed by filtration indicates that the organic solid is insoluble in ethane and, it is supposed, in methane. An upper limit is placed on the soluble fraction of 0.03% by mass. When the mixing ratio of CH4 is varied from 10 to 100% it is found that the organic solid produced becomes progressively darker in the ultraviolet and violet (0.2-0.4 mu m) compared to the visible and near-infrared (0.4-0.75 mu m). The optical properties are variable by more than a factor of 2 between experiments. Sedimentation of solid haze comparatively small loss for carbon. For nitrogen, however, the loss rate of 10(8) N atoms cm(-2) s(-1) in haze material is greater than 10% of the total production of N in the upper atmosphere. Published by Elsevier Science Ltd RP McKay, CP (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 35 TC 105 Z9 106 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD AUG PY 1996 VL 44 IS 8 BP 741 EP 747 DI 10.1016/0032-0633(96)00009-8 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VU303 UT WOS:A1996VU30300002 ER PT J AU Phillips, N Oren, R Zimmermann, R AF Phillips, N Oren, R Zimmermann, R TI Radial patterns of xylem sap flow in non-, diffuse- and ring-porous tree species SO PLANT CELL AND ENVIRONMENT LA English DT Article DE Liquidambar styraciflua; Pinus taeda; Quercus alba; soil moisture; transpiration; xylem ID HEAT PULSE METHOD; WATER-FLOW; TRANSPIRATION; PERMEABILITY; FORESTS; TRUNKS; OAK AB We investigated radial patterns of sap flux density and wood properties in the sapwood of young loblolly pine (Pinus taeda L.), mature white oak (Quercus alba L.) and sweetgum (Liquidambar styraciflua L.), which represent three major classes of wood anatomy: non-porous (coniferous), ring-porous and diffuse-porous, Radial measurements of xylem sap flux density were made in sections of xylem extending to 20 mm and 20-40 mm from the cambium, These measurements were compared with measurements of the relative water content (R(s)) and sapwood specific gravity (rho(f)) of corresponding radial sections, In both hardwood species, sap flow differences were rarely significant between the two depth intervals, In pine, a 59% reduction in daily sap flux density from outer to inner sapwood was found, This could not be accounted for by a 3% drop in R(s); rather, an accompanying 9% reduction in rho(f) indicated a transition between the depth intervals from mature to juvenile sapwood, and is the probable cause of the lower flux rate in the inner xylem of pine. C1 DUKE UNIV,NICHOLAS SCH ENVIRONM,DURHAM,NC 27708. CALTECH,JET PROP LAB,TERR SCI GRP,PASADENA,CA 91109. NR 39 TC 214 Z9 244 U1 2 U2 69 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0140-7791 J9 PLANT CELL ENVIRON JI Plant Cell Environ. PD AUG PY 1996 VL 19 IS 8 BP 983 EP 990 DI 10.1111/j.1365-3040.1996.tb00463.x PG 8 WC Plant Sciences SC Plant Sciences GA VB601 UT WOS:A1996VB60100009 ER PT J AU Otoshi, TY AF Otoshi, TY TI The fractional frequency stability of a 34-m-diameter beam waveguide antenna (vol 82, pg 788, 1994) SO PROCEEDINGS OF THE IEEE LA English DT Correction, Addition RP Otoshi, TY (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9219 J9 P IEEE JI Proc. IEEE PD AUG PY 1996 VL 84 IS 8 BP 1187 EP 1187 DI 10.1109/JPROC.1996.535140 PG 1 WC Engineering, Electrical & Electronic SC Engineering GA UY250 UT WOS:A1996UY25000012 ER PT J AU Stelzried, CT Klein, MJ AF Stelzried, CT Klein, MJ TI Precision DSN radiometer systems: Impact on microwave calibrations (vol 82, pg 776, 1994) SO PROCEEDINGS OF THE IEEE LA English DT Correction, Addition RP Stelzried, CT (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9219 J9 P IEEE JI Proc. IEEE PD AUG PY 1996 VL 84 IS 8 BP 1187 EP 1187 DI 10.1109/JPROC.1996.535139 PG 1 WC Engineering, Electrical & Electronic SC Engineering GA UY250 UT WOS:A1996UY25000011 ER PT J AU Alcorn, CW Croom, MA Francis, MS AF Alcorn, CW Croom, MA Francis, MS TI The X-31 aircraft: Advances in aircraft agility and performance SO PROGRESS IN AEROSPACE SCIENCES LA English DT Article AB The X-31 enhanced fighter maneuverability (EFM) demonstrator has pioneered agile flight in the post-stall flight regime and explored integrated multi-axis thrust vectoring across a broad flight envelope. Its maneuvering achievements include sustained flight up to 70 degrees angle of attack, velocity vector rolls in deep post-stall conditions, and post-stall turns from high entry to exit speeds with ultra low turning/transitional conditions. The concept of post-stall maneuverability was extensively studied in simulations preceding initiation of the X-31 program. These simulations provided a baseline for tactical utility demonstrations and vehicle design requirements. Post-stall maneuverability was not achieved without encountering and mitigating the effects of highly unsteady, asymmetric, vortex-dominated flow-fields associated with post-stall flight. Anomalies in vehicle response to control inputs were observed at high angles of attack, as were differences between simulator and actual flight parameters due to a misrepresentation of the effects of these complex flowfields. Some preliminary force and moment data for the X-31 configuration during dynamic maneuvers are provided to highlight the complex nature of the flowfield. The X-31 aircraft's enabling capabilities, including multi-axis thrust vectoring and integrated flight/propulsion control also provided performance enhancements across the entire flight envelope. In what were known as 'quasi-tailless' experiments, conventional aerodynamic control surfaces were used to reduce or eliminate the stabilizing influence of the vertical stabilizer, while the vehicle's multi-axis thrust vectoring capability was used for restabilization. Properly exploited, these technologies can lead to the reduction or elimination of traditional aerodynamic control surfaces, which provides profound improvements in vehicle range, weight, payload, and low observability. This review focuses on some of the principal aerodynamic issues encountered during the course of the X-31 program, the resulting lessons learned, and the derived results concerning the complex aerodynamic effects associated with exploiting this aircraft's unique capabilities. Suggested research and technology development issues which came to light during the X-31 program are also discussed. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. ADV RES PROJECTS AGCY,ARLINGTON,VA 22203. DAIMLER BENZ AEROSP,D-800 MUNICH 80,GERMANY. RP Alcorn, CW (reprint author), SRS TECHNOL,ARLINGTON,VA 22203, USA. NR 46 TC 16 Z9 21 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0376-0421 J9 PROG AEROSP SCI JI Prog. Aeosp. Sci. PD AUG PY 1996 VL 32 IS 4 BP 377 EP 413 DI 10.1016/0376-0421(95)00006-2 PG 37 WC Engineering, Aerospace SC Engineering GA UL147 UT WOS:A1996UL14700003 ER PT J AU Knebel, TF AF Knebel, TF TI Event-related potentials during dual task performance: Tracking and auditory discrimination SO PSYCHOPHYSIOLOGY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC PSYCHOPHYSIOL RES PI WASHINGTON PA 1010 VERMONT AVE NW SUITE 1100, WASHINGTON, DC 20005 SN 0048-5772 J9 PSYCHOPHYSIOLOGY JI Psychophysiology PD AUG PY 1996 VL 33 SU 1 BP S52 EP S52 PG 1 WC Psychology, Biological; Neurosciences; Physiology; Psychology; Psychology, Experimental SC Psychology; Neurosciences & Neurology; Physiology GA VF577 UT WOS:A1996VF57700204 ER PT J AU Rosekind, MR Gregory, K Miller, D Webbon, L Oyung, R AF Rosekind, MR Gregory, K Miller, D Webbon, L Oyung, R TI Evaluating fatigue in operational settings: The NASA Ames fatigue countermeasures program SO PSYCHOPHYSIOLOGY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SAN JOSE STATE UNIV,SAN JOSE,CA 95192. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC PSYCHOPHYSIOL RES PI WASHINGTON PA 1010 VERMONT AVE NW SUITE 1100, WASHINGTON, DC 20005 SN 0048-5772 J9 PSYCHOPHYSIOLOGY JI Psychophysiology PD AUG PY 1996 VL 33 SU 1 BP S13 EP S13 PG 1 WC Psychology, Biological; Neurosciences; Physiology; Psychology; Psychology, Experimental SC Psychology; Neurosciences & Neurology; Physiology GA VF577 UT WOS:A1996VF57700052 ER PT J AU Lauroesch, JT Truran, JW Welty, DE York, DG AF Lauroesch, JT Truran, JW Welty, DE York, DG TI QSO absorption-line systems and early chemical evolution SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Review ID DAMPED LYMAN-ALPHA; C-IV ABSORPTION; RADIO-QUIET GALAXY; METAL-POOR STARS; HIGH-RESOLUTION SPECTROSCOPY; HIGH-REDSHIFT GALAXIES; EXTREME HALO STARS; DIFFUSE CLOUDS; ZETA-OPHIUCHI; ELEMENT ABUNDANCES AB Heavy-element absorption-line systems in spectra of QSOs represent unique probes of gas at high redshifts, An understanding of these systems will be important for theories of galaxy formation and large-scale structure. By using spectroscopic studies to obtain abundances in QSO absorption-line systems at different redshifts, it is possible to observe clues to the nucleosynthetic history of objects, at a large range in redshift, that are presumably at different points in their evolution. In principle, one could imagine using abundance ratios to identify absorbing gas in which the heavy elements are predominantly those produced in Type II SNe (as are the Galactic halo and oldest disk stars) and those which have a mixture of the products of Type I and Type II SNe (like the gas and young stars of the Galactic disk), We review the present state of abundance measurements in damped Lyman-alpha systems, as well as recent results of studies of Galactic halo-star and interstellar abundances. We also briefly discuss the results of imaging studies of fields around QSOs showing absorption by intervening gas, and the results of statistical analyses of the change in number of observed QSO absorption-line systems with redshift. The range of overall abundances (10(-0.5) to 10(-3) solar) found in the absorbers (at redshifts of 0.6-3.4) overlaps the range found in Galactic halo stars. Specific, measurable tracers of supernova activity and dust grain formation in the absorber population are identified. While the available data for O and S are sparse, there is evidence for systems with [Si/Fe]similar to+0.4, a distinguishing characteristic of Galactic halo-star abundances. Dust-free gas with halo-star abundances and solar-metallicity gas with a Galactic cold-cloud depletion pattern are excluded by existing data. Additional observations of absorption-line systems with 10(19)21.5 than the 4'.6 radius parallel field discussed by Paresce and colleagues. This indicates that the dynamical process of mass segregation is occurring in the cluster. C1 NEW MEXICO STATE UNIV,DEPT ASTRON,LAS CRUCES,NM 88003. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV MICHIGAN,DEPT ATMOSPHER & OCEAN SCI,ANN ARBOR,MI 48109. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. JOHNS HOPKINS UNIV,DEPT ASTRON,BALTIMORE,MD 21218. CALTECH,JET PROP LAB,PASADENA,CA 91109. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP Mould, JR (reprint author), AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,INST ADV STUDIES,WESTON CREEK PO,WESTON,ACT 2611,AUSTRALIA. NR 16 TC 8 Z9 8 U1 0 U2 2 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD AUG PY 1996 VL 108 IS 726 BP 682 EP 687 DI 10.1086/133785 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VC744 UT WOS:A1996VC74400006 ER PT J AU Abuelgasim, AA Gopal, S Irons, JR Strahler, AH AF Abuelgasim, AA Gopal, S Irons, JR Strahler, AH TI Classification of ASAS multiangle and multispectral measurements using artificial neural networks SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID ART AB Because the anisotropy of the Earth's surface reflectance is strongly influenced by vegetation cover, multidirectional remotely sensed data can be highly effective in discriminating among Land cover classes. This article explores the use of multiangle and multispectral data from the Advanced Solid-State Array Spectroradiometer (ASAS) in land cover mapping using artificial neural networks. A multilayer feed-forward neural network is trained to identify five land cover classes in Voyageurs National Park, Minnesota. Multiangle data achieve 89% of accuracy when applied to a single band (774-790 nm), 7-directional imagery and 88% accuracy when applied to multispectral nadir data. Analysis of error using the confusion matrix indicates that the higher classification accuracy is obtained primarily for three classes: deciduous forest, wetlands, and water. The results suggest that 1) directional radiance measurements contain much useful information for discrimination among land cover classes, 2) the incorporation of more than one spectral multiangle band improves the overall classification accuracy compared to a single multiangle band, and 3) neural networks can successfully learn class discriminations from directional radiance data and/or multidomain data. C1 BOSTON UNIV, DEPT GEOG, BOSTON, MA 02215 USA. NASA, GODDARD SPACE FLIGHT CTR, BIOSPHER SCI BRANCH, GREENBELT, MD 20771 USA. RP Abuelgasim, AA (reprint author), BOSTON UNIV, CTR REMOTE SENSING, 725 COMMONWEALTH AVE, BOSTON, MA 02215 USA. RI Irons, James/D-8535-2012 NR 28 TC 43 Z9 44 U1 0 U2 5 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG PY 1996 VL 57 IS 2 BP 79 EP 87 DI 10.1016/0034-4257(95)00197-2 PG 9 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA VC415 UT WOS:A1996VC41500002 ER PT J AU Karnieli, A Shachak, M Tsoar, H Zaady, E Kaufman, Y Danin, A Porter, W AF Karnieli, A Shachak, M Tsoar, H Zaady, E Kaufman, Y Danin, A Porter, W TI The effect of microphytes on the spectral reflectance of vegetation in semiarid regions SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID INDEX; BIOMASS; IMAGES; CANOPY; RED AB The normalized difference vegetation index (NDVI), which is derived from satellite sensor images, is widely used as a measure of vegetation and ecosystem dynamics, change in land use, desertification, and climatic change processes on a regional or global scale. Surprisingly, in semiarid regions, relatively high values of NDVI were measured in landscapes where little, if any, photosynthetic activity of higher plants exists. We tested the hypothesis that the high NDVI values may be caused by the photosynthetic activity of microphytes (lower plants), consisting of mosses, lichens, algae, and cyanobacteria, which cover most of the rock and soil surfaces in semiarid regions. We found that the spectral reflectance curves of lower plants can be similar to those of the higher ones and their derived NDVI values can be as high as 0.30 units. We conclude that, in semiarid environments, the reflectance of lower plant communities may lead to misinterpretation of the vegetation dynamics and overestimation of ecosystem productivity. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. HEBREW UNIV JERUSALEM,JERUSALEM,ISRAEL. UNIV WISCONSIN,MADISON,WI. RP Karnieli, A (reprint author), BEN GURION UNIV NEGEV,JACOB BLAUSTEIN INST DESERT RES,REMOTE SENSING LAB,SEDE BOKER CAMPUS,IL-84990 SEDE BOQER,ISRAEL. NR 36 TC 65 Z9 69 U1 1 U2 12 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG PY 1996 VL 57 IS 2 BP 88 EP 96 DI 10.1016/0034-4257(95)00209-X PG 9 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA VC415 UT WOS:A1996VC41500003 ER PT J AU Gazis, PR AF Gazis, PR TI Solar cycle variation in the heliosphere SO REVIEWS OF GEOPHYSICS LA English DT Review ID INTERPLANETARY MAGNETIC-FIELD; LARGE HELIOCENTRIC DISTANCES; CORONAL MASS EJECTIONS; COSMIC-RAY GRADIENTS; OUTER HELIOSPHERE; TERMINATION SHOCK; LARGE-SCALE; CURRENT SHEET; WIND STREAM; SPACECRAFT OBSERVATIONS AB Variations in interplanetary plasma and magnetic field parameters over the course of a solar cycle affect a broad range of physical phenomena, such as planetary magnetospheres, cosmic ray modulation, and the interaction of the solar wind with the local interstellar medium. For more than 3 decades a succession of spacecraft have provided in situ measurements of these parameters. These measurements span a range of heliocentric distances from 0.3 to 61 AU and provide an explicit picture of the three-dimensional structure of the inner and outer heliosphere in the vicinity of the ecliptic plane. In addition, ground-based interplanetary scintillation measurements and observations from the Ulysses spacecraft have extended our knowledge to smaller heliocentric distances and higher heliographic latitudes. The structure of the heliosphere varies dramatically over the course of a solar cycle. Much of this variation can be related to the changes in the structure and inclination of the coronal magnetic field. The coronal neutral line, which separates the Sun's magnetic hemispheres, is associated with a belt of low-speed and high-density solar wind. Its inclination varies over the course of a solar cycle, from a low value near solar minimum to a high value near solar maximum. When the inclination of the coronal neutral line is low, its signature is evident in observations near the solar equator. When the inclination of the coronal neutral line is high, the heliosphere at moderate heliographic latitudes is swept by a succession of high- and low-speed streams and is shaped by their interactions. RP Gazis, PR (reprint author), NASA,AMES RES CTR,SJSU FDN,MOFFETT FIELD,CA 94035, USA. NR 154 TC 47 Z9 48 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 8755-1209 J9 REV GEOPHYS JI Rev. Geophys. PD AUG PY 1996 VL 34 IS 3 BP 379 EP 402 DI 10.1029/96RG00892 PG 24 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA VD587 UT WOS:A1996VD58700004 ER PT J AU Marten, K Shariff, K Psarakos, S White, DJ AF Marten, K Shariff, K Psarakos, S White, DJ TI Ring bubbles of dolphins SO SCIENTIFIC AMERICAN LA English DT Article C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Marten, K (reprint author), EARTHTRUST,PROJECT DELPHIS,25 KANEOHE BAY DR,KAILUA,HI 96734, USA. OI Shariff, Karim/0000-0002-7256-2497 NR 3 TC 12 Z9 14 U1 2 U2 8 PU SCI AMERICAN INC PI NEW YORK PA 415 MADISON AVE, NEW YORK, NY 10017 SN 0036-8733 J9 SCI AM JI Sci.Am. PD AUG PY 1996 VL 275 IS 2 BP 82 EP 87 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UX611 UT WOS:A1996UX61100034 PM 8693325 ER PT J AU Feng, D Schnabel, RB AF Feng, D Schnabel, RB TI Tensor methods for equality constrained optimization SO SIAM JOURNAL ON OPTIMIZATION LA English DT Article DE constrained optimization; tensor methods; singular problems; successive quadratic programming ID NONLINEAR EQUATIONS; CONVERGENCE; ALGORITHMS AB This paper introduces tensor methods for nonlinear equality constrained optimization problems. These are general purpose methods intended especially for problems where the constraint gradient matrix at the solution is rank deficient or ill conditioned. The new methods are adapted from the standard successive quadratic programming method by augmenting the linear model of the constraints with a simple second-order term. The second-order term is selected so that the model of the constraints interpolates constraint function values from one or more previous iterations, as well as the current constraint function value and gradients. Similar to tensor methods for nonlinear equations, the tensor methods for constrained optimization require no more function and derivative evaluations, and hardly more storage or arithmetic per iteration, than the standard SQP methods. Test results indicate that the tensor methods are more efficient than SQP methods on singular and nonsingular nonlinear equality constrained optimization problems, with a particularly large advantage on singular problems. C1 UNIV COLORADO,DEPT COMP SCI,BOULDER,CO 80309. RP Feng, D (reprint author), NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035, USA. NR 25 TC 4 Z9 5 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER PH#382-9800, PHILADELPHIA, PA 19104-2688 SN 1052-6234 J9 SIAM J OPTIMIZ JI SIAM J. Optim. PD AUG PY 1996 VL 6 IS 3 BP 653 EP 673 DI 10.1137/S1052623494270790 PG 21 WC Mathematics, Applied SC Mathematics GA VC017 UT WOS:A1996VC01700008 ER PT J AU Kariyappa, R Pap, JM AF Kariyappa, R Pap, JM TI Contribution of chromospheric features to UV irradiance variability from spatially-resolved Ca II K spectroheliograms .1. A new method of analysis and preliminary results SO SOLAR PHYSICS LA English DT Article ID SOLAR ULTRAVIOLET IRRADIANCE; MODULATION; LUMINOSITY; FLUX AB We have digitized the Ca II K spectroheliograms, observed at the National Solar Observatory at Sacramento Peak, for the period 1980 (maximum of solar cycle 21), 1985 (minimum of solar cycle 21), 1987 (beginning of the ascending phase of solar cycle 22), 1988 and 1989 (ascending phase and maximum of solar cycle 22), and 1992 (declining phase of solar cycle 22). A new method for analyzing the K spectroheliograms has been developed and applied to the K images for the time interval of 1992. Using histograms of intensity, we have segregated and measured the cumulative intensity acid area of various chromospheric features like the plages, magnetic network and intranetwork elements. Also, the full width at half maximum (FWHM) derived from the histograms has been introduced as a new index for describing the chromospheric activity in the K-line. The full-disk intensity (spatial K index) has been derived from spatially-resolved K images and compared to the spectral K index derived from the line profiles for the full disk. Both the spatial K index and FWHM have been compared to the UV irradiance measured in the Mg II h and k lines by the NOAA9 satellite and found that they are highly correlated with the Mg II h and k c/w ratio. C1 UNIV CALIF LOS ANGELES,DEPT PHYS & ASTRON,LOS ANGELES,CA. RP Kariyappa, R (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA, USA. NR 16 TC 15 Z9 15 U1 0 U2 0 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 AUG PY 1996 VL 167 IS 1-2 BP 115 EP 123 DI 10.1007/BF00146331 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB303 UT WOS:A1996VB30300009 ER PT J AU Pap, JM Vigouroux, A Delache, P AF Pap, JM Vigouroux, A Delache, P TI Study of the distribution of daily fluctuations in observed solar irradiances and other full-disk indices of solar activity SO SOLAR PHYSICS LA English DT Article ID PHOTOMETRIC SUNSPOT INDEX; LYMAN-ALPHA; ULTRAVIOLET IRRADIANCE; VARIABILITY; LUMINOSITY; CYCLE; TIME; SUN; DEPENDENCE; MODEL AB Analyses based on irradiance observations from space within the last one and a half decades have discovered variations in the entire solar spectrum and at UV wavelengths on time scales of minutes to decades. In this paper we analyze the distribution of the measuring uncertainties and daily fluctuations in total solar irradiance measured by the Nimbus-7/ERB and SMM/ACRIM I radiometers as a function of solar cycle. Changes in solar total irradiance and its surrogates shorter than the solar rotation have also been considered as 'noise' and have been removed from the data. Our results show that the noise (both instrumental and solar noise) changes as a function of the solar cycle, being higher during high solar activity conditions. The analysis of the scatter plot diagrams between the data and their standard deviation, the so-called 'dispersion diagrams', provides a useful tool to estimate and predict the time of solar maximum and minimum activity conditions. C1 UNIV CALIF LOS ANGELES,DIV ASTRON & ASTROPHYS,LOS ANGELES,CA 90095. UNIV CALIF LOS ANGELES,DEPT PHYS & ASTRON,LOS ANGELES,CA 90095. OBSERV COTE AZUR,CNRS URA 1362,LAB CASSINI,F-06304 NICE 04,FRANCE. RP Pap, JM (reprint author), CALTECH,JET PROP LAB,MS 169-506,PASADENA,CA 91109, USA. NR 37 TC 8 Z9 8 U1 0 U2 0 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 AUG PY 1996 VL 167 IS 1-2 BP 125 EP 143 DI 10.1007/BF00146332 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB303 UT WOS:A1996VB30300010 ER PT J AU Alissandrakis, CE Borgioli, F Drago, FC Hagyard, M Shibasaki, K AF Alissandrakis, CE Borgioli, F Drago, FC Hagyard, M Shibasaki, K TI Coronal magnetic fields from microwave polarization observations SO SOLAR PHYSICS LA English DT Article ID EMISSION AB The solar active region (AR) 7530 was observed at 6 cm on July 3 and 4, 1993 with the Westerbork Synthesis Radio Telescope, using a multi-channel receiver with very narrow bandwidth. We compare the radio data with Yohkoh SXT observations and with the magnetic field extrapolated from the Marshall vector magnetograms in the force-free and current-free approximations. The comparison with soft X-rays shows that, although a general agreement exists between the shape of the radio intensity map and the X-ray loops, the brightness temperature, T-b, Obtained using the parameters derived from the SXT is much lower than that observed. The comparison with the extrapolated photospheric fields shows instead that they account very well for the observed T-b above the main sunspots, if gyroresonance emission is assumed. In the observation of July 4 an inversion and strong suppression of the circular polarization was clearly present above different portions of the AR, which indicates that particular relationships exist between the electron density and the magnetic field in the region where the corresponding lines of sight cross the field quasi-perpendicularly. The extrapolated magnetic field at a much higher level (similar to 10(10) cm), satisfies the constraints required by the wave propagation theory all over the AR. However, a rather low electron density is derived. C1 UNIV FLORENCE, DEPT ASTRON & SPACE SCI, I-50125 FLORENCE, ITALY. GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. NOBEYAMA RADIO OBSERV, NAGANO, JAPAN. RP UNIV IOANNINA, SECT ASTROGEOPHYS, IOANNINA 45110, GREECE. OI Borgioli, Francesca/0000-0003-3779-1662 NR 14 TC 16 Z9 16 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 EI 1573-093X J9 SOL PHYS JI Sol. Phys. PD AUG PY 1996 VL 167 IS 1-2 BP 167 EP 179 DI 10.1007/BF00146335 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VB303 UT WOS:A1996VB30300013 ER PT J AU Greene, PR Brown, OS Medina, AP Graupner, HB AF Greene, PR Brown, OS Medina, AP Graupner, HB TI Emmetropia approach dynamics with diurnal dual-phase cycling SO VISION RESEARCH LA English DT Article DE animal experiments; control theory; dynamic response; emmetropia; focusing; myopia ID DARK FOCUS; MYOPIA; ACCOMMODATION; MODEL AB Numerical experiments are performed on a first order exponential response function subjected to a diurnal square wave visual environment with variable duty cycle. The model is directly applicable to exponential drift of focal status. A two-state square wave is employed as the forcing function with high B for time H and low A for time L. Duty cycles of (1/3), (1/2) and (2/3) are calculated in detail. Results show the following standard linear system response: (1) Unless the system runs into the stops, the steady state equilibrium settling level is always between A and B. The level is linearly proportional to a time-weighted average of the high and low states. (2) The effective time constant t(eff) varies hyperbolically with duty cycle. For DC = (1/3) and t1 = 100 days, the effective time constant is lengthened to 300 days. An asymptote is encountered under certain circumstances where t(eff) approaches infinity. (3) Effective time constants and steady state equilibria are independent of square wave frequency f, animal time constant t1, magnitude and sign of A & B, and diurnal sequencing of the highs and lows. By presenting results on dimensionless coordinates, we can predict the drift rates of some animal experiments. Agreement between theory and experiment has a correlation coefficient r = 0.97 for 12 Macaca nemestrina eyes. Copyright (C) 1996 Elsevier Science Ltd. C1 JOHNS HOPKINS UNIV,DEPT BIOMED ENGN,BALTIMORE,MD. MCDONNELL DOUGLAS CORP,SPACE STN INTEGRAT,SEABROOK,MD. CALTECH,JET PROP LAB,PASADENA,CA. BGKT CONSULTING,STONY BROOK,NY. FU NEI NIH HHS [EY-05013] NR 20 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0042-6989 J9 VISION RES JI Vision Res. PD AUG PY 1996 VL 36 IS 15 BP 2249 EP 2251 DI 10.1016/0042-6989(95)00338-X PG 3 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA VA096 UT WOS:A1996VA09600002 PM 8776489 ER PT J AU Hsieh, CI Katul, GG Schieldge, J Sigmon, J Knoerr, KR AF Hsieh, CI Katul, GG Schieldge, J Sigmon, J Knoerr, KR TI Estimation of momentum and heat fluxes using dissipation and flux-variance methods in the unstable surface layer SO WATER RESOURCES RESEARCH LA English DT Article ID TURBULENT KINETIC-ENERGY; SENSIBLE HEAT; GRADIENT RELATIONSHIPS; UNIVERSAL FUNCTIONS; 1976 ITCE; TEMPERATURE; CONSTANT; EXCHANGE; BUDGETS; OCEAN AB Dissipation and flux-variance methods, derived from the turbulent kinetic energy and temperature variance budget equations in conjunction with Monin-Obukov similarity theory, were used to estimate surface fluxes of momentum and sensible heat. To examine the performance of these two methods, direct eddy correlation measurements were carried out above a nonuniform grass-covered forest clearing in Durham, North Carolina. The dissipation method sensible heat flux predictions were iii good agreement with eddy correlation measurements. Also, the flux-variance method reproduced the measured sensible heat flux well following an adjustment to the similarity constant. However, the momentum flux (or friction velocity) estimated by the dissipation and flux-variance methods were both inferior to those for sensible heat flux. The data from this experiment indicated that the above two methods are sensitive to the dimensionless wind shear (phi(m)) and temperature standard deviation (phi(theta)) functions. On the basis of dimensional analysis and the temperature variance budget equation a new dissipation approach for estimating sensible heat flux was derived. The similarity constant for this new approach was shown to be around 1.6 for uniform surfaces and from the data of this experiment. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP DUKE UNIV, SCH ENVIRONM, BOX 90328, DURHAM, NC 27708 USA. RI Katul, Gabriel/A-7210-2008 OI Katul, Gabriel/0000-0001-9768-3693 NR 43 TC 25 Z9 26 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0043-1397 EI 1944-7973 J9 WATER RESOUR RES JI Water Resour. Res. PD AUG PY 1996 VL 32 IS 8 BP 2453 EP 2462 DI 10.1029/96WR01337 PG 10 WC Environmental Sciences; Limnology; Water Resources SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Water Resources GA VA834 UT WOS:A1996VA83400011 ER PT J AU Wang, PKC Gutierrez, RC Bartman, RK AF Wang, PKC Gutierrez, RC Bartman, RK TI A method for designing electrostatic-actuator electrode pattern in micromachined deformable mirrors SO SENSORS AND ACTUATORS A-PHYSICAL LA English DT Article DE deformable mirrors; electrostatic actuators; micromachining AB A rational method for designing the electrostatic-actuator electrode pattern in micromachined deformable mirrors based on specifying the mirror surface deformation at prescribed points in the mirror's spatial domain corresponding to given actuator voltages is presented. The application of the proposed method is illustrated by an example involving a circular mirror modelled by an elastic membrane. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Wang, PKC (reprint author), UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,LOS ANGELES,CA 90024, USA. NR 8 TC 11 Z9 11 U1 0 U2 1 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0924-4247 J9 SENSOR ACTUAT A-PHYS JI Sens. Actuator A-Phys. PD JUL 31 PY 1996 VL 55 IS 2-3 BP 211 EP 217 DI 10.1016/S0924-4247(97)80080-5 PG 7 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA VZ290 UT WOS:A1996VZ29000022 ER PT J AU Fielding, EJ AF Fielding, EJ TI Tibet uplift and erosion SO TECTONOPHYSICS LA English DT Article; Proceedings Paper CT 10th Himalaya-Karakoram-Tibet Workshop on Uplift and Exhumation of Metamorphic Rocks - The Himalayan Tibet Region CY APR 04-08, 1995 CL ASCONA, SWITZERLAND ID INDIA-ASIA COLLISION; FISSION-TRACK THERMOCHRONOLOGY; LATE CENOZOIC UPLIFT; ULUGH-MUZTAGH AREA; SOUTHERN TIBET; TECTONIC EVOLUTION; THERMAL EVOLUTION; EURASIA COLLISION; COOLING HISTORY; NORTHERN TIBET AB The 5-km-high Tibetan plateau is an outstanding topographic feature on the Earth today. Its horizontal extent, elevation, and location cause significant effects on modem atmospheric circulation and climate, so the history of uplift of the surface of Tibet is linked to Cenozoic climate changes, at local, regional, and perhaps global scales. Geological and geophysical studies of the plateau are contributing data on the present and past deformation of the Tibetan lithosphere that has formed the plateau, primarily during the Cenozoic. The principal of isostasy then can be used to estimate the elevation history of the surface for a given deformation history. Different parts of Tibet probably had different uplift histories, but presently available data are not sufficient for distinguishing many contrasts. In one scenario, Cretaceous and Early Cenozoic north-south distributed shortening of Tibetan crust and mantle lithosphere probably caused significant uplift of the surface relative to sea level to perhaps half of the present elevation by the early Miocene. Thinning of the high-density mantle portion of the lithosphere during the Miocene may then have allowed the thick Tibetan crust to rise close to its present elevation (perhaps higher) before similar to 8 Ma. Since then, slow east-west extension of Tibet probably reduced the crustal thickness slightly and may have caused the elevation of the plateau to decrease during the late Cenozoic. Erosion of Tibet, unlike narrow mountain belts, has been unable to match the uplift of a broad plateau. Orographic precipitation and efficient river networks concentrate erosion on the edges, while the interior is protected from significant erosion despite its lofty elevation. The southern edge of the plateau, the Himalaya, has suffered a minimum of 25 km of denudation since the Miocene, while central Tibet shows little or no sign of major erosion since that time. The Gangdese are in southern Tibet was rapidly eroded during the mid-Miocene when >4 km of rock apparently were removed from the surface, as shown by mineral cooling ages. This pulse of erosion was probably caused by a combination of local thrust-system movement and changes in base level and precipitation due to relative elevation changes between the Gangdese and the Himalaya to the south. The modern long-wavelength flatness of Tibet is unlikely to have been caused by erosion and indicates viscous flow at some level of the lithosphere has been acting to level the plateau surface. RP Fielding, EJ (reprint author), CALTECH,JET PROP LAB,MAIL STOP 300-233,4800 OAK GROVE DR,PASADENA,CA 91109, USA. OI Fielding, Eric/0000-0002-6648-8067 NR 120 TC 103 Z9 133 U1 5 U2 26 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD JUL 30 PY 1996 VL 260 IS 1-3 BP 55 EP 84 DI 10.1016/0040-1951(96)00076-5 PG 30 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA VN728 UT WOS:A1996VN72800005 ER PT J AU Goodstein, D Chui, T Harter, A AF Goodstein, D Chui, T Harter, A TI Heat-flow induced anomalies in superfluid He-4 near T-lambda SO PHYSICAL REVIEW LETTERS LA English DT Article RP Goodstein, D (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91125, USA. NR 4 TC 8 Z9 8 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 JUL 29 PY 1996 VL 77 IS 5 BP 979 EP 979 DI 10.1103/PhysRevLett.77.979 PG 1 WC Physics, Multidisciplinary SC Physics GA UY952 UT WOS:A1996UY95200050 ER PT J AU Zheng, SH Srivastava, SK AF Zheng, SH Srivastava, SK TI Electron-impact ionization and dissociative ionization of acetylene SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID CROSS-SECTIONS; UPPER-ATMOSPHERE; BINDING-ENERGY; C2H2; ELECTROIONIZATION; URANUS; REGION; C2D2; IONS AB A pulsed electron beam and ion extraction system has been employed to measure cross sections for formation of C2H2+, C2H+, C-2(+), C2H2++ + CH+, C-2(++) C+ and H+ by electron impact on acetylene (C2H2) in the energy range varying from threshold to 800 eV. The relative flow technique has been used to obtain normalized values of cross sections. Appearance potentials (APS) for ionic species are reported. Present values of APS are compared with previously published data. RP Zheng, SH (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 36 Z9 36 U1 0 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD JUL 28 PY 1996 VL 29 IS 14 BP 3235 EP 3244 DI 10.1088/0953-4075/29/14/028 PG 10 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA VA528 UT WOS:A1996VA52800028 ER PT J AU Chao, WC Deng, LT AF Chao, WC Deng, LT TI On the role of wind-induced surface heat exchange in a two-dimensional model of super cloud clusters SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPICAL INTRASEASONAL OSCILLATION; ATMOSPHERE AB Experiments with a two-dimensional model of Chao and Lin [1994] are conducted to investigate the role of WISHE (wind-induced surface heat exchange) in the super cloud clusters. It is found that while WISHE as an instability mechanism is not responsible for the existence of the super cloud clusters, the process of surface fluxes being enhanced by surface wind has the important roles of prolonging the life span of the cloud clusters and making the super cloud clusters more robust. WISHE is also found not responsible for upstream propagation of the super cloud cluster. The latter is explained by the cloud cluster teleinduction mechanism proposed by Chao and Lin [1994]. C1 APPL RES CORP, LANDOVER, MD 20785 USA. RP Chao, WC (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, MAIL CODE 913, GREENBELT, MD 20771 USA. NR 11 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 JUL 27 PY 1996 VL 101 IS D12 BP 16931 EP 16937 DI 10.1029/96JD01224 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UZ750 UT WOS:A1996UZ75000003 ER PT J AU Green, N Hinton, PO AF Green, N Hinton, PO TI Estimation of angular distribution models from radiance pairs SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RADIATION BUDGET; NIMBUS-7 ERB; EARTH AB A new approach to constructing angular distribution models (ADMs) from satellite data has been developed. The ADMs model the radiance anisotropy and are used to convert satellite measured radiance to flux at the top of the atmosphere. The radiance pairs method (RPM) processes radiance pairs that view approximately the same area at the same time. By ratioing the paired radiances, the flux or field strength is eliminated, producing ratios of anisotropies which are taken as the data source for the ADMs. The ADMs are modeled as random functions, and the RPM estimates the mean of the ADM. The RPM is compared to the standard method of sorting by angular bins (SAB) and is shown to remove questionable assumptions, converge faster, and give better accuracy than the SAB method. Both methods were applied to the same Nimbus 7 ERB data and resulted in statistically different longwave ADMs. C1 SCI APPLICAT INT CORP, HAMPTON, VA 23666 USA. RP Green, N (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. NR 10 TC 11 Z9 11 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 JUL 27 PY 1996 VL 101 IS D12 BP 16951 EP 16959 DI 10.1029/96JD00368 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UZ750 UT WOS:A1996UZ75000005 ER PT J AU Lubin, D Chen, JP Pilewskie, P Ramanathan, V Valero, FPJ AF Lubin, D Chen, JP Pilewskie, P Ramanathan, V Valero, FPJ TI Microphysical examination of excess cloud absorption in the tropical atmosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OPTICAL-CONSTANTS; ULTRAVIOLET; SCATTERING; RADIATION; MODELS; BUDGET; REGION; WATER; ICE AB To investigate the excess shortwave absorption by clouds, a numerical cloud generation model has been coupled to a plane-parallel discrete ordinates radiative transfer model. The former was used in a time-dependent fashion to generate a cumulonimbus turret and three types of cirrus anvil (precipitating, extended, detached) representing three stages of cloud evolution outward from the turret. The cloud particle size distributions, as a function of altitude, were used as input to the radiative transfer model using indices of refraction for pure water and pure ice and equivalent sphere Mie theory. The radiative transfer model was used to calculate the ratio of cloud forcing at the surface to cloud forcing at the top of the atmosphere, both for the broadband shortwave and as a function of wavelength. Recent empirical studies have placed this cloud forcing ratio at around 1.5, and our coupled model results approach this value for small solar zenith angles, when the cloud contains large (>100 mu m) ice particles that absorb significantly in the near infrared (primarily the 1.6-mu m window). However, the empirical studies are based on diurnal averages, and our plane-parallel radiative transfer model yields an area and diurnally averaged cloud forcing ratio of only 1.18 for a tropical cumulonimbus and cirrus anvil system, primarily because of the rapid decrease of the ratio with solar zenith angle. The ratio decreases because of the increase in albedo with solar zenith angle, which is a characteristic feature of plane-parallel clouds. Adding dust or aerosol to the cloud layers, to make them absorb at visible wavelengths, makes the instantaneous cloud forcing ratio larger for an overhead Sun but also makes the solar zenith angle dependence in the cloud forcing ratio more pronounced. These two effects cancel, eliminating interstitial aerosol as a possible explanation for the excess cloud absorption in plane-parallel radiative transfer modeling. The strong dependence of the surface/top of the atmosphere cloud forcing ratio on solar zenith angle may be a fundamental defect with the plane-parallel approach to solar radiative transfer in a cloudy atmosphere. C1 UNIV CALIF SAN DIEGO, SCRIPPS INST OCEANOG, CTR ATMOSPHER SCI, LA JOLLA, CA 92093 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV CALIF SAN DIEGO, SCRIPPS INST OCEANOG, ATMOSPHER RES LAB, LA JOLLA, CA 92093 USA. UNIV CALIF SAN DIEGO, CALIF SPACE INST, LA JOLLA, CA 92093 USA. RI Chen, Jen-Ping/F-2947-2010 OI Chen, Jen-Ping/0000-0003-4188-6189 NR 25 TC 19 Z9 19 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 JUL 27 PY 1996 VL 101 IS D12 BP 16961 EP 16972 DI 10.1029/96JD01154 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UZ750 UT WOS:A1996UZ75000006 ER PT J AU Mishchenko, MI Rossow, WB Macke, A Lacis, AA AF Mishchenko, MI Rossow, WB Macke, A Lacis, AA TI Sensitivity of cirrus cloud albedo, bidirectional reflectance and optical thickness retrieval accuracy to ice particle shape SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MULTIPLE-SCATTERING CALCULATIONS; INVARIANT IMBEDDING METHOD; RADIATIVE PROPERTIES; LIGHT-SCATTERING; POLARIZED-LIGHT; PLANETARY ATMOSPHERES; INFRARED RADIANCES; OCTOBER 1986; MIXED-PHASE; CRYSTALS AB We examine the sensitivity of cirrus cloud albedo and bidirectional reflection function to particle shape using the phase functions of liquid water spheres, regular hexagonal ice crystals, and random-fractal ice particles calculated at a nonabsorbing visible wavelength of 0.63 mu m. Accurate multiple-scattering calculations for plane-parallel clouds show that hexagonal ice crystal clouds have systematically larger planetary and global albedos than liquid water clouds of the same optical thickness; There is accumulating evidence that the idealized phase function of regular hexagonal crystals, which causes pronounced halos, is not necessarily the best representation of the range of reflectance characteristics of the majority of ice clouds. A more typical representation of the scattering phase function for ice clouds that are composed of a complex set of crystal shapes and sizes may be obtained using a model of randomly shaped irregular particles. Even larger cloud albedos are obtained for the random-fractal particle model because of its smaller asymmetry parameter. Our computations also show that a larger planetary albedo does not always imply a larger reflectance and that the relative brightness of ice versus liquid water clouds is highly scattering-geometry dependent. Use of the wrong particle shape model (crystal instead of water droplet and vice versa) in retrieving cloud optical thickness from bidirectional reflectance measurements can result in an underestimation or overestimation of the true optical thickness by a factor that can exceed 3. At some scattering geometries, use of the wrong model can give an unrealistically large optical thickness or no solution at all. Overall, bidirectional reflectance differences between random-fractal and regular hexagonal particle shapes are significantly smaller than those between either ice crystal and liquid water spheres, except at the back scattering direction. C1 COLUMBIA UNIV, NEW YORK, NY 10025 USA. SUNY STONY BROOK, INST TERR & PLANETARY ATMOSPHERES, STONY BROOK, NY 11794 USA. RP Mishchenko, MI (reprint author), NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Lacis, Andrew/D-4658-2012; Rossow, William/F-3138-2015; Mishchenko, Michael/D-4426-2012 NR 47 TC 122 Z9 123 U1 1 U2 8 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 JUL 27 PY 1996 VL 101 IS D12 BP 16973 EP 16985 DI 10.1029/96JD01155 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UZ750 UT WOS:A1996UZ75000007 ER PT J AU Hsu, CS Liu, WT AF Hsu, CS Liu, WT TI Wind and pressure fields near tropical cyclone Oliver derived from scatterometer observations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SEASAT-A; II STORM; SATELLITE; PREDICTION; HURRICANES; INTENSITY; EVOLUTION; WEATHER; IMPACT AB The results of this study demonstrate that the surface wind velocity and pressure fields derived from spaceborne scatterometers are useful id monitoring the location and intensity of tropical cyclones. Satellite-borne microwave scatterometers can penetrate the cloudy core regions of tropical cyclones to resolve the circulation in detail over data sparse regions. The location of the cyclone observed by the ERS-1 scatterometer is very close to that revealed in Geostationary Meteorological Satellite images. The surface winds provided by the ERS-1 scatterometer are used here with a modified two-layer planetary boundary layer model which includes effects of curvature, stability, and secondary flow to derive surface pressures near tropical cyclone Oliver. The curvature effect is found to be more significant than stability and secondary flow, which are crucial in deriving accurate surface pressure fields in midlatitudes. RP Hsu, CS (reprint author), CALTECH, JET PROP LAB, 300-323, PASADENA, CA 91109 USA. NR 34 TC 20 Z9 21 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 JUL 27 PY 1996 VL 101 IS D12 BP 17021 EP 17027 DI 10.1029/96JD01229 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UZ750 UT WOS:A1996UZ75000010 ER PT J AU Driscoll, KT Blakeslee, RJ AF Driscoll, KT Blakeslee, RJ TI Current budget of the atmospheric electric global circuit - Comment SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Editorial Material ID THUNDERSTORMS C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, EARTH SYST SCI LAB, HUNTSVILLE, AL 35806 USA. UNIV ALABAMA, GLOBAL HYDROL & CLIMATE CTR, HUNTSVILLE, AL 35899 USA. RP Driscoll, KT (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, INST GLOBAL CHANGE RES & EDUC, 977 EXPLORER BLVD, HUNTSVILLE, AL 35806 USA. NR 16 TC 4 Z9 4 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 JUL 27 PY 1996 VL 101 IS D12 BP 17037 EP 17040 DI 10.1029/95JD01534 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UZ750 UT WOS:A1996UZ75000013 ER PT J AU Andersson, K Bauschlicher, CW Persson, BJ Roos, BO AF Andersson, K Bauschlicher, CW Persson, BJ Roos, BO TI The structure of dichromium tetraformate SO CHEMICAL PHYSICS LETTERS LA English DT Article ID 2ND-ORDER PERTURBATION-THEORY; MOLECULAR WAVE-FUNCTIONS; FIELD REFERENCE FUNCTION; TRANSITION-METAL ATOMS; GAUSSIAN-BASIS SETS; CR QUADRUPLE BOND; ANO BASIS-SETS; ENERGY; REPRESENTATION; ACCURATE AB Second-order perturbation theory (CASPT2) calculations using large basis sets have been used to study the Cr-Cr bond in dichromium tetraformate, Cr-2(O2CH)(4). The Cr-Cr potential was found to have a double minimum with one short equilibrium at 1.94 Angstrom, exhibiting considerable 3d-3d bonding, and a long equilibrium at 2.50 Angstrom, which is essentially determined by the structure of the bridging ligands. The energy difference between the two minima is small (of the order of 0.1 eV) and the relative order-depends on the level of theory used. Inclusion of relativistic effects and 3s,3p correlation (estimated from the corresponding effect in the (3) Sigma(u)(+) State of Cr-2) locates the inner minimum 0.07 eV below the outer. The measured distance in Cr-2(O2CCH3)(4) is 1.966 Angstrom. It is likely that addition of axial ligands like water will make the outer minimum more stable, thus explaining the variations in Cr-Cr distances in dichromium complexes. The DFT approach is also applied and long, 2.296 and 2.487 Angstrom, Cr-Cr bond distances are found for Cr-2(O2CH)(4) and Cr-2(O2CCH3)(4), respectively. Addition of axial water ligands increases the Cr-Cr distance by about 0.19 and 0.07 Angstrom, respectively, for these two systems. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF SAN DIEGO,DEPT CHEM & BIOCHEM,SAN DIEGO,CA 92186. SAN DIEGO SUPERCOMP CTR,SAN DIEGO,CA 92186. RP Andersson, K (reprint author), DEPT CHEM,POB 124,S-22100 LUND,SWEDEN. NR 31 TC 29 Z9 29 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUL 26 PY 1996 VL 257 IS 3-4 BP 238 EP 248 DI 10.1016/0009-2614(96)00552-0 PG 11 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UZ049 UT WOS:A1996UZ04900004 ER PT J AU Wang, M Lele, SK Moin, P AF Wang, M Lele, SK Moin, P TI Sound radiation during local laminar breakdown in a low-Mach-number boundary layer SO JOURNAL OF FLUID MECHANICS LA English DT Article ID NUMERICAL-SIMULATION; AERODYNAMIC SOUND; SHEAR FLOWS; TRANSITION; NOISE; TURBULENT; WAVE; DISTURBANCES AB The far-field sound of an unstable wave packet undergoing transition in a low-Mach-number, hat-plate boundary layer is investigated in the framework of Lighthill's acoustic analogy. Detailed accounts of the wave packet evolution are obtained by solving the full incompressible Navier-Stokes equations at Re-delta = 1000. The numerically simulated flow structures show qualitative agreement with experimental observations of the fundamental breakdown type. The acoustic calculations are focused on the quadrupole source functions arising from Reynolds stress fluctuations. The wave packet is shown to produce negligible sound throughout the primary and secondary instability stages. Dramatic amplification of the Reynolds stress quadrupoles occurs as a result of the disintegration of the detached high-shear layer and the associated vortex shedding near the boundary layer edge. The dominant frequency of source oscillations coincides with that of vortex shedding. RP Wang, M (reprint author), NASA, AMES RES CTR, CTR TURBULENCE RES, MOFFETT FIELD, CA 94035 USA. RI Wang, Meng/C-1622-2012 NR 57 TC 27 Z9 31 U1 0 U2 2 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUL 25 PY 1996 VL 319 BP 197 EP 218 DI 10.1017/S0022112096007318 PG 22 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA VD013 UT WOS:A1996VD01300009 ER PT J AU Neumann, GA Zuber, MT Smith, DE Lemoine, FG AF Neumann, GA Zuber, MT Smith, DE Lemoine, FG TI The lunar crust: Global structure and signature of major basins SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CLEMENTINE MISSION; HARMONIC-ANALYSIS; IMPACT CRATERS; MOON; INVERSION; EVOLUTION; GRAVITY; TOPOGRAPHY; ANOMALIES; MODEL AB New lunar gravity and topography data from the Clementine Mission provide a global Bouguer anomaly map corrected for the gravitational attraction of mare fill in mascon basins. Most of the gravity signal remaining after corrections for the attraction of topography and mare fill can be attributed to variations in depth to the lunar Moho and therefore crustal thickness. The large range of global crustal thickness (similar to 20-120 km) is indicative of major spatial variations in melting of the lunar exterior and/or significant impact-related redistribution. The 61-km average crustal thickness, constrained by a depth-to-Moho measured during the Apollo 12 and 14 missions, is preferentially distributed toward the farside, accounting for much of the offset in center-of-figure from the center-of-mass. While the average farside thickness is 12 km greater than the nearside, the distribution is nonuniform, with dramatic thinning beneath the farside, South Pole-Aitken basin. With the global crustal thickness map as a constraint, regional inversions of gravity and topography resolve the crustal structure of major mascon basins to half wavelengths of 150 km, In order to yield crustal thickness maps with the maximum horizontal resolution permitted by the data, the downward continuation of the Bouguer gravity is stabilized by a three-dimensional, minimum-slope and curvature algorithm. Both mare and non-mare basins are characterized by a central upwarped moho that is surrounded by rings of thickened crust lying mainly within the basin rims. The inferred relief at this density interface suggests a deep structural component to the surficial features of multiring lunar impact basins. For large (>300 km diameter) basins, moho relief appears uncorrelated with diameter, but is negatively correlated with basin age. In several cases, it appears that the multiring structures were out of isostatic equilibrium prior to mare emplacement, suggesting that the lithosphere was strong enough to maintain their state of stress to the present. C1 NASA, GODDARD SPACE FLIGHT CTR, TERR PHYS LAB, GREENBELT, MD 20771 USA. RP JOHNS HOPKINS UNIV, DEPT EARTH & PLANETARY SCI, BALTIMORE, MD 21218 USA. RI Lemoine, Frank/D-1215-2013; Neumann, Gregory/I-5591-2013 OI Neumann, Gregory/0000-0003-0644-9944 NR 87 TC 150 Z9 162 U1 0 U2 13 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 JUL 25 PY 1996 VL 101 IS E7 BP 16841 EP 16863 DI 10.1029/96JE01246 PG 23 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UZ728 UT WOS:A1996UZ72800003 ER PT J AU Forget, F Pollack, JB AF Forget, F Pollack, JB TI Thermal infrared observations of the condensing Martian polar caps: CO2 ice temperatures and radiative budget SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID RADIO OCCULTATION MEASUREMENTS; SEASONAL CO-2 CYCLE; GENERAL-CIRCULATION; DUST STORMS; INTERANNUAL VARIABILITY; VIKING OBSERVATIONS; SURFACE PRESSURE; MARS; ATMOSPHERE; SIMULATIONS AB The physical processes that control the formation of the Martian seasonal polar caps are not completely understood. On the one hand, climate models reproducing the annual variations in atmospheric pressure caused by the condensation of the polar caps have shown that the amount of CO2 actually trapped in the polar regions in winter is lower than expected from simple energy balance considerations. On the other hand, the available spacecraft observations of the condensing polar caps are complex and puzzling. They are characterized by highly variable low-emission zones exhibiting anomalously cold brightness temperatures. To better understand these results we have carefully reanalyzed the Viking infrared thermal mapper (IRTM) measurements obtained during the polar night in both hemispheres. First, by removing the signature of the low-emission zones in the data, we have retrieved the actual surface temperatures of the polar caps. We find that they were lower than the frost point of CO2 for the topography of the polar regions usually used in models, especially in the south polar region, However, our analysis reveals that the low-emission zones were more frequent and more intense in the northern hemisphere. They strongly altered the polar radiative budget which is computed and analyzed here, and thus the CO2 condensation rate. We conclude that the models' tendency to overestimate the amount of CO2 ice condensing in the polar caps is explained by different causes in each hemisphere. In the north, the models did not simulate the low-emission zones and underestimated the heat advected to the polar cap region during the dust storms, especially by the upper atmosphere polar warming. In the south, they overestimated the polar cap surface temperatures and also did not simulate the low-emission zones. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Forget, F (reprint author), ECOLE NORMALE SUPER,CNRS,METEOROL DYNAM LAB,24 RUE LHOMOND,F-75231 PARIS 05,FRANCE. NR 31 TC 36 Z9 36 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUL 25 PY 1996 VL 101 IS E7 BP 16865 EP 16879 DI 10.1029/96JE01077 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UZ728 UT WOS:A1996UZ72800004 ER PT J AU Barnes, JR Walsh, TD Murphy, JR AF Barnes, JR Walsh, TD Murphy, JR TI Transport timescales in the Martian atmosphere: General circulation model simulations SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID SOLAR OCCULTATION MEASUREMENTS; MIDDLE ATMOSPHERE; VERTICAL STRUCTURE; MARS; WAVES; STRATOSPHERE; DYNAMICS; AEROSOLS; WATER AB Simulations with a Mars general circulation model (GCM) are used to perform idealized tracer transport experiments, which are analyzed to yield estimates of eddy mixing coefficients as well as ''stratospheric'' ventilation timescales for the zonal-mean circulation. The results indicate that relatively moderate values of the vertical eddy mixing coefficient, K-z similar to N 20-100 m(2)/s, may be most appropriate for the 10 to 45-km altitude region of the Martian atmosphere. Under dusty solstice conditions, somewhat stronger eddy mixing is present, but the transport is dominated by advection by the mean meridional circulation which acts to ventilate the atmosphere above 1 mbar (similar to 20 km) in only about 7 days. Such a mean circulation has transport effects which are roughly comparable to those produced by eddy mixing with a much larger K-z value, similar to 1500 m(2)/s. In contrast, the computed mean ventilation timescale for a nondusty equinox circulation is approximately 180 days. In this case, vertical eddy mixing is the dominant transport process. In an intermediate nondusty solstice case, the effects of mean advection and eddy mixing are of comparable importance. An estimate of a mean ventilation timescale from the GCM for a late northern winter seasonal date (similar to 45 days) is in very good agreement with the value of similar to 38 days recently inferred from Mariner 9 infrared imaging spectrometer (IRIS) data [Santee and Crisp, 1995]. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SAN JOSE UNIV FDN,SAN JOSE,CA. RP Barnes, JR (reprint author), OREGON STATE UNIV,COLL OCEAN & ATMOSPHER SCI,104 OCEAN ADM BLDG,CORVALLIS,OR 97331, USA. NR 30 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUL 25 PY 1996 VL 101 IS E7 BP 16881 EP 16889 DI 10.1029/96JE00500 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UZ728 UT WOS:A1996UZ72800005 ER PT J AU Thorn, RP Monks, PS Stief, LJ Kuo, SC Zhang, ZY Klemm, RB AF Thorn, RP Monks, PS Stief, LJ Kuo, SC Zhang, ZY Klemm, RB TI Photoionization efficiency spectrum, ionization energy, and heat, of formation of Br2O SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID HOBR; THERMOCHEMISTRY; RADICALS; BROMINE; BRO AB The photoionization efficiency (PIE) spectrum of Br2O was measured over the wavelength range lambda = 100-125 nm by using a photoionization mass spectrometer apparatus coupled to a synchrotron radiation source. A value of 10.26(4) +/- 0.01(1) eV was obtained for the adiabatic ionization energy of Br2O from analysis of the photoionization thresholds. Also, the appearance energy (AE) of BrO+ (from the dissociative ionization of Br2O) was determined from the PIE spectrum of BrO+ over the wavelength range lambda = 104-110 nm. Combining the AE(298) value, 11.71(4) +/- 0.01(4) eV, with known thermodynamic quantities yields a value for Delta(f)H degrees(298)(Br2O) = 107.1 +/- 3.5 kJ mol(-1). The value for Delta(f)H degrees(298)(Br2O) may be related to Delta(f)H degrees(298)(HOBr) through the equilibrium constant for the reaction Br2O + H2O reversible arrow 2HOBr. This leads to Delta(f)H degrees(298)(HOBr) = -60.0 +/- 3.5 kJ mol(-1). C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. BROOKHAVEN NATL LAB,DEPT APPL SCI,UPTON,NY 11973. RI Monks, Paul/H-6468-2016 OI Monks, Paul/0000-0001-9984-4390 NR 30 TC 29 Z9 29 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUL 25 PY 1996 VL 100 IS 30 BP 12199 EP 12203 PG 5 WC Chemistry, Physical SC Chemistry GA UY938 UT WOS:A1996UY93800012 ER PT J AU Heidbrink, JL Li, JG Pan, WP Gooding, JL Aubuchon, S Foreman, J Lundgren, CJ AF Heidbrink, JL Li, JG Pan, WP Gooding, JL Aubuchon, S Foreman, J Lundgren, CJ TI Distinction of nontronite from palagonite by thermal analysis and evolved-gas analysis: Application to Mars surface exploration SO THERMOCHIMICA ACTA LA English DT Article; Proceedings Paper CT 24th North-American-Thermal-Analysis-Society Conference CY SEP 10-13, 1995 CL SAN FRANCISCO, CA SP N Amer Thermal Anal Soc DE evolved gas analysis; soil; thermal analysis AB Alternative models for the soils of Mars have invoked either the mineral nontronite (an iron-rich smectite clay) or the mineraliod palagonite fan oxidized, hydrated alteration product of basalt glass) as the major silicate component. Laboratory tests on representative terrestrial minerals demonstrate that nontronite is distinguishable from palagonite by their respective responses to combined thermal and evolved-gas analysis. When subjected to differential scanning calorimetry (DSC) or simultaneous thermogravimetric analysis and differential thermal analysis (SDT), combined with mass spectrometry (MS) of evolved gases, nontronite and palagonite differ in the onset temperatures, peak intensities, and peak profiles for their respective dehydration reactions. Using operating conditions apporpriate for a small planetary surface instrument (40 degrees C min(-1), 50 mi Ar min(-1)), nontronite dehydration peaks are sharply centered at similar to 120-125 degrees C and similar to 460-490 degrees C; equivalent peaks for palagonite occur more broadly at similar to 125-145 degrees C and similar to 620 degrees C. Further distinctions can be made from detailed shapes of the respective SDT profiles, especially at temperatures of 1000-1300 degrees C. The SDT-MS data also reveal minor carbonates, sulfates, and nitrates naturally admired with the major silicates. C1 WESTERN KENTUCKY UNIV,DEPT CHEM,BOWLING GREEN,KY 42101. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. TA INSTRUMENTS INC,NEW CASTLE,DE 19720. NR 4 TC 5 Z9 5 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-6031 J9 THERMOCHIM ACTA JI Thermochim. Acta PD JUL 25 PY 1996 VL 284 IS 1 BP 241 EP 251 DI 10.1016/0040-6031(96)02920-6 PG 11 WC Thermodynamics; Chemistry, Analytical; Chemistry, Physical SC Thermodynamics; Chemistry GA VC198 UT WOS:A1996VC19800020 ER PT J AU Noor, AK Peters, JM AF Noor, AK Peters, JM TI Nonlinear and postbuckling analyses of curved composite panels subjected to combined temperature change and edge shear SO COMPUTERS & STRUCTURES LA English DT Article ID REDUCED BASIS TECHNIQUE; CYLINDRICAL PANELS; COLLAPSE ANALYSIS; CUTOUTS AB The results of a detailed study of the nonlinear and postbuckling responses of curved unstiffened composite panels with central circular cutouts are presented. The panels are subjected to uniform temperature change and an applied in-plane edge shear loading. The analysis is based on a first-order shear-deformation Sanders-Budiansky type theory with the effects of large displacements, moderate rotations, transverse shear deformation and laminated anisotropic material behavior included. A mixed formulation is used with the fundamental unknowns consisting of the generalized displacements and the stress resultants of the panel. The nonlinear displacements, strain energy, transverse shear stresses, transverse shear strain energy density, and their hierarchical sensitivity coefficients are evaluated. Numerical results are presented for cylindrical panels with central circular cutouts and are subjected to uniform temperature change and an applied in-plane edge shear loading. The results show the effects of variations in the panel curvature, hole diameter, laminate stacking sequence and fiber orientation, on the nonlinear and postbuckling panel responses, and their sensitivity to changes in the various panel, layer and micromechanical parameters. Copyright (C) 1996 Published by Elsevier Science Ltd RP Noor, AK (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR ADV COMPUTAT TECHNOL,HAMPTON,VA 23665, USA. NR 22 TC 3 Z9 3 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD JUL 24 PY 1996 VL 60 IS 6 BP 853 EP 874 DI 10.1016/0045-7949(95)00456-4 PG 22 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA UV023 UT WOS:A1996UV02300001 ER PT J AU Macke, A Mishchenko, MI AF Macke, A Mishchenko, MI TI Applicability of regular particle shapes in light scattering calculations for atmospheric ice particles SO APPLIED OPTICS LA English DT Article; Proceedings Paper CT OSA 1995 Annual Meeting CY 1995 CL PORTLAND, OR SP Opt Soc Amer ID CIRRUS CLOUDS; NONSPHERICAL PARTICLES; RADIATIVE PROPERTIES; SNOW CRYSTALS AB We ascertain the usefulness of simple ice particle geometries for modeling the intensity distribution of light scattering by atmospheric ice particles. To this end, similarities and differences in light scattering by axis-equivalent, regular and distorted hexagonal cylindric, ellipsoidal, and circular cylindric ice particles are reported. All the results pertain to particles with sizes much larger than a wavelength and are based on a geometrical optics approximation. At a nonabsorbing wavelength of 0.55 mu m, ellipsoids (circular cylinders) have a much (slightly) larger asymmetry parameter g than regular hexagonal cylinders. However, our computations show that only random distortion of the crystal shape leads to a closer agreement with g values as small as 0.7 as derived from some remote-sensing data analysis. This may suggest that scattering by regular particle shapes is not necessarily representative of real atmospheric ice crystals at nonabsorbing wavelengths. On the other hand, if real ice particles happen to be hexagonal, they may be approximated by circular cylinders at absorbing wavelengths. (C) 1996 Optical Society of America C1 COLUMBIA UNIV,DEPT APPL PHYS,NEW YORK,NY 10025. SUNY STONY BROOK,INST TERR & PLANETARY ATMOSPHERES,STONY BROOK,NY 11794. RP Macke, A (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Mishchenko, Michael/D-4426-2012 NR 22 TC 62 Z9 63 U1 0 U2 5 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 1996 VL 35 IS 21 BP 4291 EP 4296 DI 10.1364/AO.35.004291 PG 6 WC Optics SC Optics GA VA608 UT WOS:A1996VA60800039 PM 21102838 ER PT J AU Horack, JM Mallozzi, RS Koshut, TM AF Horack, JM Mallozzi, RS Koshut, TM TI Reconciling gamma-ray burst time-dilation measurements to the brightness distribution in the context of standard cosmology SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology, theory; gamma rays, bursts AB If gamma-ray bursts are located at cosmological distances, it is natural to expect that measurements of cosmological time dilation in the burst profiles or cosmological energy shifting in burst spectral forms must agree with other cosmological signatures such as the brightness distribution's deviation from a -3/2 logarithmic slope. Recently, several works have offered evidence for time dilation and energy stretching in gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE). We therefore present a means to assess the consistency of time-dilation and energy-shifting measurements with both the brightness distribution of BATSE and various Friedmann cosmological models. This methodology can be utilized with energy-width corrections of various sizes that are inherent to time-dilation analyses, yet absent in energy-shifting measurements. Following the presentation of the general technique, we utilize the methodology to assess the compatibility of a recent claim by Norris et al. of a time dilation factor of 2.25 from bursts separated by a factor of 21 in brightness. We show that these results are not compatible with the brightness distribution of BATSE assuming a nonevolving population of standard-candle bursts embedded in an Einstein-de Sitter universe. Recent revisions of this value downward to 1.75 published by Norris in 1995 help to alleviate the discrepancy; however, they are still somewhat marginal in light of the energy-width corrections that need to be applied. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. RP Horack, JM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. RI Horack, John/J-6670-2016 NR 23 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1996 VL 466 IS 1 BP 21 EP 28 DI 10.1086/177490 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW721 UT WOS:A1996UW72100003 ER PT J AU Rakos, KD Maindl, TI Schombert, JM AF Rakos, KD Maindl, TI Schombert, JM TI Photometric signatures of starbursts in interacting galaxies and the Butcher-Oemler effect SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, evolution; galaxies, photometry; galaxies, starburst ID NARROW-BAND PHOTOMETRY; SPECTROPHOTOMETRIC ATLAS; POPULATION SYNTHESIS; STELLAR POPULATIONS; CHEMICAL EVOLUTION; INFRARED GALAXIES; GLOBAL PROPERTIES; HALO DWARFS; ABUNDANCES; SPECTRA AB This paper presents new and synthetic narrowband photometry of ellipticals, spirals, Seyferts, and interacting galaxies in an attempt to identify the cause of the unusually high fraction of blue cluster galaxies in distance clusters (Butcher-Oemler effect). The properties and distribution of the low-redshift sample specifically points to starbursts as the origin of the blue narrowband colors in interacting Arp galaxies. Comparison between theoretical models and multicolor diagrams, particularly 4000 Angstrom break colors, indicates a photometric signature that differs from both normal disk galaxy star formation and nonthermal components. This photometric signature is absent for the Butcher-Oemler galaxies whose general color distribution, compared to present-day clusters, is consistent with a majority of the blue population involved in normal star formation rates (spiral-like) with the addition of a small fraction of bright, blue interacting/merger systems. This photometric picture of the Butcher-Oemler galaxies is in agreement with the morphological evidence from Hubble Space Telescope imaging. C1 CALTECH,CTR INFRARED PROC & ANAL,JET PROPULS LAB,PASADENA,CA 91125. RP Rakos, KD (reprint author), UNIV VIENNA,INST ASTRON,WAEHRINGER GUERTEL 18,A-1010 VIENNA,AUSTRIA. NR 54 TC 24 Z9 24 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1996 VL 466 IS 1 BP 122 EP 134 DI 10.1086/177497 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW721 UT WOS:A1996UW72100010 ER PT J AU Heiles, C Reach, WT Koo, BC AF Heiles, C Reach, WT Koo, BC TI Radio recombination lines from inner galaxy diffuse gas .2. The extended low-density warm ionized medium and the ''worm-ionized medium'' SO ASTROPHYSICAL JOURNAL LA English DT Article DE diffuse radiation; H II regions; ISM, bubbles; ISM, structure; radiative transfer; radio continuum, ISM; radio lines, ISM ID H-II-REGIONS; SOUTHERN GALACTIC PLANE; INTERSTELLAR-MEDIUM; FREQUENCY SURVEY; FREE-ELECTRONS; STAR FORMATION; MILKY-WAY; 325 MHZ; EMISSION; SHELLS AB We have searched for 1.4 GHz radio recombination lines (RRLs) at 583 positions, mostly toward the galactic interior, and achieved detections at 418 positions. These data characterize the extended low-density warm ionized medium (the ELDWIM). We derive an electron temperature of 7000 K from a comparison of RRL and radio continuum, and estimate that non-LTE effects increase the line intensities by a factor of similar to 1.3. We examine the distribution of the ELDWIM with a velocity-longitude diagram and find some concentration into spiral arms. The ELDWIM is not particularly well correlated with strong H II regions. The azimuthally symmetric inner Galaxy ring component of Taylor & Cordes does not appear in RRL emission, and we propose a revised model in which its electrons are located farther out in spiral arms. We derive the ELDWIM filling factor phi(WIM) similar to 0.01 and an electron density in the emitting regions of similar to 5 cm(-3). A fraction of the diffuse radio continuum and 100 mu m IR emission is characterized by vertical structures that correspond well to the ''worm'' and ''chimney'' models, in which clustered supernovae blow large cavities in the gaseous disk that, for chimneys, connect to the gaseous halo. We interpret the RRL emission from these structures in terms of the ''worm-ionized medium'' (W-IM), in which the thermal radio emission arises in the worm walls; the walls are ionized by photons from hot stars in the cluster whose supernovae originally produced the cavity. The nearest example of a worm is the Orion/Eridanus cavity. The previously best-studied example is the Stockert chimney, which we argue is part of a much larger structure. The worms that have well-defined distances are closely confined to spiral arms. We discuss ionization requirements for worms and their associated H II regions and define three classes that describe the ionization of worm walls. These classes depend on the state of star formation in the central molecular cloud, which eventually dissipates. The global ionization requirement for all worm walls is small (similar to 20%) compared to the total requirement for the Galactic ELDWIM. High-\z\ CO may be associated with at least two worms. C1 NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. SEOUL NATL UNIV, DEPT ASTRON, SEOUL 151742, SOUTH KOREA. RP Heiles, C (reprint author), UNIV CALIF BERKELEY, DEPT ASTRON, 601 CAMPBELL HALL, BERKELEY, CA 94720 USA. RI Reach, William/C-4710-2008 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 JUL 20 PY 1996 VL 466 IS 1 BP 191 EP 223 DI 10.1086/177503 PN 1 PG 33 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW721 UT WOS:A1996UW72100016 ER PT J AU Lipunov, VM Ozernoy, LM Popov, SB Postnov, KA Prokhorov, ME AF Lipunov, VM Ozernoy, LM Popov, SB Postnov, KA Prokhorov, ME TI Population synthesis of X-ray sources at the Galactic center SO ASTROPHYSICAL JOURNAL LA English DT Article DE Galaxy, center; stars, evolution; stars, formation; stars, neutron stars, statistics; X-rays, stars ID NEUTRON-STAR ACCRETION; MASSIVE BINARY-SYSTEMS; CLOSE BINARIES; STELLAR WIND; EVOLUTION; EMISSION; NUMBER; GALAXY AB We are exploring the evolution of massive binary star populations for a nuclear starburst occurring in the conditions similar to the Milky Way Galaxy, in its central part, on a timescale of 10 Myr. A computer code is applied allowing for computing, by using Monte Carlo simulations, the evolution of a large ensemble of binary systems, with proper accounting for spin evolution of magnetized neutron stars (NSs). Our results include a number of X-ray transients (each consisting of a NS plus main-sequence star), superaccreting black holes (BHs), and binaries consisting of a BH plus a supergiant, all as functions of time. We find that by 7 Myr after such a starburst one expects approximate to 1 X-ray source with a BH (Cyg X-1 type), approximate to 1 SS 433-like source (BH in the regime of superaccretion), and approximate to 37 transient sources with a NS, all to be within the central 1 kpc or so. An interesting result that can be considered a specific starburst feature is that the ratio of the number of systems like SS 433 to the number of X-ray transients is about 1:100, compared with 1:1000 characteristic of the average ratio in the Galactic field. The ratio of the total number of X-ray sources containing a BH (of Cyg X-1 plus SS 433 types) to the number of X-ray transients with NSs turns out to be a sensitive function of the age of the starburst, and its computed value approximate to 0.04 is consistent with observations. C1 GEORGE MASON UNIV, DEPT PHYS & ASTRON, FAIRFAX, VA 22030 USA. GEORGE MASON UNIV, INST COMPUTAT SCI & INFORMAT, FAIRFAX, VA 22030 USA. NASA, GSFC, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RP Lipunov, VM (reprint author), MOSCOW MV LOMONOSOV STATE UNIV, STERNBERG ASTRON INST, MOSCOW 119899, RUSSIA. RI Popov, Sergei/B-6368-2008 OI Popov, Sergei/0000-0002-4292-8638 NR 56 TC 11 Z9 11 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 JUL 20 PY 1996 VL 466 IS 1 BP 234 EP 241 DI 10.1086/177505 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW721 UT WOS:A1996UW72100018 ER PT J AU Reames, DV Barbier, LM Ng, CK AF Reames, DV Barbier, LM Ng, CK TI The spatial distribution of particles accelerated by coronal mass ejection-driven shocks SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; shock waves; Sun, corona; Sun, particle emission ID SOLAR ENERGETIC PARTICLES; INTERPLANETARY SHOCKS; ION-ACCELERATION; HE-3-RICH EVENTS; FLARES; WAVES; WIND AB We use multispacecraft observations to examine the spatial and temporal distributions of energetic particles accelerated by shock waves driven by coronal mass ejections from the Sun. The behavior of the intensity time profiles ahead of the shock can depend strongly on the longitude of the point where the observer's magnetic flux tube connects to the shock, relative to the nose of the shock where acceleration is strongest. Particle intensities can increase (decrease) with time as this point swings eastward through greater than or equal to 50 degrees toward (away from) the shock nose because of solar rotation. Well behind the shock, intensities are often constant with longitude and the intensities of these quasi-trapped particles at all energies decrease continuously with time over many days as their containment volume expands. Delayed proton events are produced when shocks expand into dow solar wind so they suddenly encounter an observer's field line far from the Sun. Sunward flows are seen when the shock passes over the observer or when it suddenly strikes his field line at radial distances out beyond him. C1 ROYAL MELBOURNE INST TECHNOL,MELBOURNE,VIC 3001,AUSTRALIA. RP Reames, DV (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 42 TC 145 Z9 149 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1996 VL 466 IS 1 BP 473 EP 486 DI 10.1086/177525 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW721 UT WOS:A1996UW72100038 ER PT J AU Kankelborg, CC Walker, ABC Hoover, RB Barbee, TW AF Kankelborg, CC Walker, ABC Hoover, RB Barbee, TW TI Observation and modeling of soft X-ray bright points .1. Initial results SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun, corona; Sun, magnetic fields; Sun, transition region; Sun, X-rays, gamma rays ID SOLAR TELESCOPE ARRAY; TRANSITION REGION; CORONAL LOOPS; ENERGY-BALANCE; QUIET-SUN; YOHKOH AB The Multi-Spectral Solar Telescope Array was launched from White Sands Missile Range, New Mexico, on 1991 May 13 at 1905 UT. Full-disk, high-resoluton solar images were obtained in a variety of soft X-ray and far-ultraviolet wavelengths. The 193 Angstrom (Fe XII) and 44 Angstrom (Si XII) images show a large number of coronal bright points. The high spatial resolution of the Fe XII image allows many of the bright points to be resolved as tiny loops. Co-alignment of the soft X-ray images with the 1216 Angstrom Ly alpha image reveals that all the coronal bright points have counterparts in the transition region, often resolved as a pair of footpoints, which are brighter than neighboring elements of the chromospheric network. Moreover, comparison with the KPNO magnetogram shows dipole structures coincident with nearly all of the bright points. We present a quantitative analysis based on preliminary photometry of four of the bright points that were observed. By fitting a simple, numerical loop model to the photometric data, we estimate the magnitude of the coronal heating in these structures. The rate of heating per unit footpoint area is found to be similar to previous measurements for much larger coronal structures. Implications for heating of the chromosphere and lower transition region are also discussed. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. LAWRENCE LIVERMORE NATL LAB, LIVERMORE, CA 94550 USA. RP STANFORD UNIV, DEPT PHYS & APPL PHYS, STANFORD, CA 94305 USA. NR 30 TC 26 Z9 26 U1 0 U2 0 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 JUL 20 PY 1996 VL 466 IS 1 BP 529 EP + DI 10.1086/177529 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW721 UT WOS:A1996UW72100042 ER PT J AU Phillips, KJH Bhatia, AK Mason, HE Zarro, DM AF Phillips, KJH Bhatia, AK Mason, HE Zarro, DM TI High coronal electron densities in a solar flare from Fe XXI and Fe XXII X-ray line measurements SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic processes; Sun, corona; Sun, flares; Sun, X-rays, gamma rays ID DIELECTRONIC SATELLITE SPECTRA; INNER-SHELL TRANSITIONS; HELIUM-LIKE IONS; MAXIMUM-MISSION; CROSS-SECTIONS; EXCITATION; RATIOS; EMISSION; PLASMA; MODEL AB New calculations of the intensities of the Fe XXI 2p(2)-2p41 X-ray lines using the distorted wave method are described and compared with observations made by a crystal spectrometer on the Solar Maximum Mission about 6 minutes after the peak of a very intense flare. The comparison enables the electron density of the flare to be derived, the value being about 2 or 3 x 10(12) cm(-3). Some nearby Fe XXII X-ray lines, scanned 1 minute after flare peak, give an even higher value, 10(13) cm(-3). This is the first time corroborated values of such high densities have been obtained from ions emitted at temperatures as high as similar to 10 MK. They imply very rapid radiation cooling rates and have other important consequences for flare models. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CAMBRIDGE,DEPT APPL MATH & THEORET PHYS,CAMBRIDGE CB3 9EW,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,APPL RES CORP,GREENBELT,MD 20771. RP Phillips, KJH (reprint author), RUTHERFORD APPLETON LAB,DEPT SPACE SCI,DIDCOT OX11 0QX,OXON,ENGLAND. NR 36 TC 51 Z9 51 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1996 VL 466 IS 1 BP 549 EP 560 DI 10.1086/177531 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW721 UT WOS:A1996UW72100044 ER PT J AU Maloney, PR Hollenbach, DJ Tielens, AGGM AF Maloney, PR Hollenbach, DJ Tielens, AGGM TI X-ray-irradiated molecular gas .1. Physical processes and general results SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic processes; infrared, ISM, lines and bands; molecular processes; radiative transfer; X-rays, ISM ID HYDROGEN GAS; PHOTODISSOCIATION REGIONS; INTERSTELLAR GRAINS; INFRARED-EMISSION; SEYFERT-GALAXIES; TIME VARIABILITY; CHARGE-TRANSFER; CROSS-SECTIONS; LINE EMISSION; DENSE CLOUDS AB We have modeled the physical and chemical state of dense (n = 10(3)-10(5) cm(-3)) neutral gas exposed to intense X-ray fluxes and the resultant infrared and submillimeter emission from the irradiated gas. The dominant parameter controlling the state of the gas in these X-ray dissociation regions (XDRs) is the ratio of local X-ray energy deposition rate to gas density; this can be expressed in terms of an effective ionization parameter. The parameter space we model ranges over 5 orders of magnitude in this ionization parameter; the gas physical conditions vary from warm, atomic, and partially ionized (T similar to 10(4) K, molecular hydrogen abundance x(H2) less than or similar to 10(-4), electron abundance x(e) similar to 0.1) to cold, molecular, and neutral (T similar to 20 K, x(H2) approximate to 0.5, x(e) similar to 10(-6)). We thus cover the entire range of parameter space in which X-ray ionization and heating is important and the gas is largely neutral. Although we assume a power law for the incident X-ray flux, most of our results are independent of this assumption and are of general applicability. A wide range of diagnostic atomic and molecular line emission is produced by XDRs, which are luminous sources of infrared and submillimeter lines. This is a consequence of the large column densities (N > 10(22) Cm-2) that hard (E > 1 keV photons are capable of penetrating before being absorbed. Strong emission lines include [Fe II] 1.26 and 1.64 mu m, [O I] 63 mu m, [C II] 158 mu m, [Si II] 35 mu m, and the 2 mu m vibration-rotation lines of H-2, such as the v = 1-0 S(1) line at 2.12 mu m. We discuss diagnostic line ratios for discriminating XDRs from shocks and photodissociation regions. One strong signature of emission from XDRs is the large flux ratio (similar to 0.1) of the major coolant line fluxes (e.g., [O I] 63 mu m) to the bolometric continuum flux. XDRs are likely to be the dominant sources of emission in a range of astrophysical environments, such as molecular clouds within roughly 1 kpc of typical active galactic nuclei. C1 UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. NATL INST STAND & TECHNOL,BOULDER,CO 80309. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Maloney, PR (reprint author), UNIV COLORADO,CTR ASTROPHYS & SPACE ASTRON,BOULDER,CO 80309, USA. NR 70 TC 426 Z9 428 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1996 VL 466 IS 1 BP 561 EP 584 DI 10.1086/177532 PN 1 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW721 UT WOS:A1996UW72100045 ER PT J AU Cannizzo, JK AF Cannizzo, JK TI The nature of the giant outbursts in the bursting pulsar GRO J1744-28 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; instabilities; pulsars, individual (GRO J1744-28); X-rays, bursts ID ACCRETION DISKS; BINARY-SYSTEMS; BLACK-HOLES AB We investigate the possible role of an accretion disk instability in producing the giant outbursts seen in GRO J1744-28. Specifically, we study the global, time-dependent evolution of the Lightman-Eardley instability, which can develop near the inner edge of an accretion disk when the radiation pressure becomes comparable to the gas pressure. Broadly speaking, our results are compatible with earlier works try Taam & Lin and by Lasota & Pelat. The uniqueness of GRO J1744-28 appears to be associated with the constraint that, in order for outbursts to occur, the rate of accretion at the inner edge must be within a narrow range just above the critical accretion rate at which radiation pressure is beginning to become significant. RP Cannizzo, JK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 662,GREENBELT,MD 20771, USA. NR 17 TC 27 Z9 27 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1996 VL 466 IS 1 BP L31 EP L34 DI 10.1086/310167 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW722 UT WOS:A1996UW72200008 ER PT J AU Mewaldt, RA Selesnick, RS Cummings, JR Stone, EC vonRosenvinge, TT AF Mewaldt, RA Selesnick, RS Cummings, JR Stone, EC vonRosenvinge, TT TI Evidence for multiply charged anomalous cosmic rays SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; interplanetary medium; solar wind ID COMPONENT; STATE; ACCELERATION; OXYGEN AB New measurements from the SAMPEX spacecraft show that most anomalous cosmic ray (ACR) oxygen nuclei with energies above 20 MeV nucleon(-1) are multiply ionized, with ionic charge states of Q = 2, Q = 3, and probably higher. This new result contrasts with lower energies, at which most ACRs are singly charged. The observed abundance of multiply charged ions agrees with estimates of the fraction of singly charged ACRs that undergo electron stripping during acceleration if the timescale for acceleration to 10 MeV nucleon(-1) is similar to 1 yr. The existence of multiply charged ACRs helps explain their acceleration to high energies, and it has implications for several other studies. C1 GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Mewaldt, RA (reprint author), CALTECH,PASADENA,CA 91125, USA. NR 25 TC 65 Z9 65 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1996 VL 466 IS 1 BP L43 EP L46 DI 10.1086/310169 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW722 UT WOS:A1996UW72200011 ER PT J AU Vaughn, CR Bufton, JL Krabill, WB Rabine, D AF Vaughn, CR Bufton, JL Krabill, WB Rabine, D TI Georeferencing of airborne laser altimeter measurements SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB The primary purpose of airborne laser altimetry is to determine the ellipsoidal or geoidal coordinates of a series of points on the surface of the Earth. An aircraft that is instrumented with a laser altimeter, an inertial navigation system, and a Global Positioning System (GPS) receiver provides the following data: (1) laser range to the Earth's surface, (2) measurement platform spatial location and orientation, and (3) aircraft kinematic trajectory in ellipsoidal coordinates. These data are sufficient to determine (georeference) the three dimensional coordinates of the points where the beam from a pulsed laser intersects the Earth. We develop the exact equations necessary to georeference the laser points. We also discuss calibrating the laser pulse timing, laser positioning and alignment relative to the local-level reference frame, correcting atmospheric refraction effects on the laser pulse, and time synchronizing the various data streams. We use a laser altimeter mission flown over Lake Crowley in California to demonstrate our methods. For seven passes over the lake, our heights agreed with a local tide gauge at the Lake Crowley dam to better than 10 cm with standard deviations ranging from 1-4 cm. The horizontal accuracy of the georeferenced points is still problematic; we have no three-dimensional control points that the laser has hit. Geometrical considerations indicate that the measured horizontal location of the laser footprint is within two metres of the true location when the aircraft altitude is less than one kilometre above the local surface. C1 NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,SCI SYST APPLICAT INC,GREENBELT,MD 20771. RP Vaughn, CR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,LAB HYDROSPHER PROC,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337, USA. RI Rabine, David/C-9626-2013 NR 17 TC 31 Z9 32 U1 1 U2 5 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 20 PY 1996 VL 17 IS 11 BP 2185 EP 2200 PG 16 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA UW885 UT WOS:A1996UW88500013 ER PT J AU Pickett, HM Peterson, DB AF Pickett, HM Peterson, DB TI Comparison of measured stratospheric OH with prediction SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID INFRARED MEASUREMENTS; INSITU MEASUREMENTS; HO2; DERIVATION; HYDROXYL; NO2 AB The production and loss of stratospheric OH involve relatively fast reactions that are in near-photochemical equilibrium. In this study, we compare OH measured by our balloon-borne far infrared limb observing spectrometer with that predicted from a simple model that uses water and ozone fields obtained from instruments on the upper atmosphere research satellite. This comparison is made for latitudes near 34 degrees N over a full diurnal cycle for five balloon flights that span a period of over 2 years. The ratio of measurement to the photochemical model at 40 km is 0.95, with an uncertainty of 0.08 (at a 90% confidence level) due to the measurement. Comparison at other altitudes and as a function of the diurnal cycle also shows excellent agreement. RP Pickett, HM (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 18 TC 28 Z9 28 U1 1 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 JUL 20 PY 1996 VL 101 IS D11 BP 16789 EP 16796 DI 10.1029/96JD01168 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UY275 UT WOS:A1996UY27500009 ER PT J AU Kivelson, MG Khurana, KK Walker, RJ Russell, CT Linker, JA Southwood, DJ Polanskey, C AF Kivelson, MG Khurana, KK Walker, RJ Russell, CT Linker, JA Southwood, DJ Polanskey, C TI A magnetic signature at Io: Initial report from the Galileo magnetometer SO SCIENCE LA English DT Article ID FLOW PAST IO; MHD SIMULATION; CURRENT SYSTEM; PLASMA TORUS; JUPITER; ALFVEN; MAGNETOSPHERE; SATELLITES; ATMOSPHERE; FIELD AB During the inbound pass of the Galileo spacecraft, the magnetometer acquired 1 minute averaged measurements of the magnetic field along the trajectory as the spacecraft flew by lo. A field decrease, of nearly 40 percent of the background jovan field at closest approach to lo, was recorded. Plasma sources alone appear incapable of generating perturbations as large as those observed and an induced source for the observed moment implies an amount of free iron in the mantle much greater than expected. On the other hand, an intrinsic magnetic field of amplitude consistent with dynamo action at lo would explain the observations. It seems plausible that lo, like Earth and Mercury, is a magnetized solid planet. C1 SCI APPLICAT INT CORP,SAN DIEGO,CA 92171. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,DEPT PHYS,LONDON SW7 2BZ,ENGLAND. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Kivelson, MG (reprint author), UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90095, USA. RI Kivelson, Margaret/I-9019-2012; OI Kivelson, Margaret/0000-0003-3859-8581; Russell, Christopher/0000-0003-1639-8298 NR 40 TC 82 Z9 85 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUL 19 PY 1996 VL 273 IS 5273 BP 337 EP 340 DI 10.1126/science.273.5273.337 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UY202 UT WOS:A1996UY20200033 ER PT J AU Noll, KS Johnson, RE Lane, AL Domingue, DL Weaver, HA AF Noll, KS Johnson, RE Lane, AL Domingue, DL Weaver, HA TI Detection of ozone on Ganymede SO SCIENCE LA English DT Article ID ION-BOMBARDMENT; SATELLITES; LIFE; REFLECTANCE; SPECTRA; SEARCH; H2O AB An absorption band at 260 nanometers on the trailing hemisphere of Ganymede, identified as the Hartley band of ozone (O-3), was measured with the Hubble Space Telescope, The column abundance of ozone, 4.5 x 10(16) per square centimeter, can be produced by ion impacts or by photochemical equilibrium with previously detected molecular oxygen (O-2). An estimated number density ratio of [O-3]/[O-2] approximate to 10(-4) to 10(-3) requires an atmospheric density orders of magnitude higher than upper limits from spacecraft occultation experiment's. Apparently, this O-2-O-3 ''atmosphere'' is trapped in Ganymede's surface ice, an inference consistent with the shift and broadening of the band compared with the gas-phase O-3 band. C1 UNIV VIRGINIA, CHARLOTTESVILLE, VA 22901 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. LUNAR & PLANETARY INST, HOUSTON, TX 77058 USA. JOHNS HOPKINS UNIV, DEPT PHYS & ASTRON, BALTIMORE, MD 21218 USA. RP Noll, KS (reprint author), SPACE TELESCOPE SCI INST, 3700 SAN MARTIN DR, BALTIMORE, MD 21218 USA. RI Noll, Keith/C-8447-2012; Weaver, Harold/D-9188-2016 NR 26 TC 120 Z9 121 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 JUL 19 PY 1996 VL 273 IS 5273 BP 341 EP 343 DI 10.1126/science.273.5273.341 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UY202 UT WOS:A1996UY20200034 PM 8662517 ER PT J AU Noor, AK Kim, YH AF Noor, AK Kim, YH TI Buckling and postbuckling of composite panels with cutouts subjected to combined edge shear and temperature change SO COMPUTERS & STRUCTURES LA English DT Article ID LAMINATED PLATES; CIRCULAR HOLE; BEHAVIOR AB The results of a detailed study of the buckling and postbuckling responses of composite panels with central circular cutouts are presented. The panels are subjected to combined edge shear and temperature change. The panels are discretized by using a two-field degenerate solid element with each of the displacement components having a linear variation throughout the thickness of the panel. The fundamental unknowns consist of the average mechanical strains through the thickness and the displacement components. The effects of geometric nonlinearities and laminated anisotropic material behavior are included. The stability boundary, postbuckling response and hierarchical sensitivity coefficients are evaluated. The hierarchical sensitivity coefficients measure the sensitivity of the buckling and postbuckling responses to variations in the panel stiffnesses, and the material properties of both the individual layers and the constituents (fibers and matrix). Numerical results are presented for composite panels with central circular cutouts subjected to combined edge shear and temperature change, showing the effects of variations in the hole diameter, laminate stacking sequence and fiber orientation, on the stability boundary and postbuckling response and their sensitivity to changes in the various panel parameters. RP Noor, AK (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR ADV COMPUTAT TECHNOL,HAMPTON,VA 23681, USA. NR 21 TC 8 Z9 8 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD JUL 17 PY 1996 VL 60 IS 2 BP 203 EP 222 DI 10.1016/0045-7949(95)00398-3 PG 20 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA UP654 UT WOS:A1996UP65400005 ER PT J AU Noor, AK Peters, JM AF Noor, AK Peters, JM TI Reduction technique for tire contact problems SO COMPUTERS & STRUCTURES LA English DT Article AB A reduction technique and a computational procedure are presented for predicting the tire contact response and evaluating the sensitivity coefficients of the different response quantities. The sensitivity coefficients measure the sensitivity of the contact response to variations in the geometric and material parameters of the tire. The tire is modeled using a two-dimensional laminated anisotropic shell theory with the effects of variation in geometric and material parameters, transverse shear deformation and geometric nonlinearities included. The contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the stress resultants, the generalized displacements, and the Lagrange multipliers associated with the contact conditions. The elemental arrays are obtained by using a modified two-field, mixed variational principle. For the application of the reduction technique, the tire finite element model is partitioned into two regions. The first region consists of the nodes that are likely to come in contact with the pavement, and the second region includes all the remaining nodes. The reduction technique is used to significantly reduce the degrees of freedom in the second region. The effectiveness of the computational procedure is demonstrated by a numerical example of the frictionless contact response of the space shuttle nose-gear tire, inflated and pressed against a rigid flat surface. RP Noor, AK (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR ADV COMPUTAT TECHNOL,HAMPTON,VA 23681, USA. NR 10 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD JUL 17 PY 1996 VL 60 IS 2 BP 223 EP 233 DI 10.1016/0045-7949(95)00370-3 PG 11 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA UP654 UT WOS:A1996UP65400006 ER PT J AU Wilson, MA Pohorille, A AF Wilson, MA Pohorille, A TI Mechanism of unassisted ion transport across membrane bilayers SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID MOLECULAR-DYNAMICS SIMULATION; LIQUID-LIQUID INTERFACE; LIPID BILAYER; POTENTIAL FUNCTIONS; VAPOR INTERFACE; WATER; PERMEABILITY; DIFFUSION; PERMEATION; HYDRATION AB To establish how charged species move from water to the nonpolar membrane interior and to determine the energetic and structural effects accompanying this process, we performed molecular dynamics simulations of the transport of Na+ and Cl- across a lipid bilayer located between two water lamellae. The total length of molecular dynamics trajectories generated for each ion was 10 ns. Our simulations demonstrate that permeation of ions into the membrane Is accompanied by the formation of deep, asymmetric thinning defects in the bilayer, whereby polar lipid head groups and water penetrate the nonpolar membrane interior. Once the ion crosses the midplane of the bilayer the deformation ''switches sides''; the initial defect slowly relaxes, and a defect forms in the outgoing side of the bilayer. Af a result, the ion remains well solvated during the process; the total number of oxygen atoms from water and lipid head groups in the first solvation shell remains constant. A similar membrane deformation is formed when the ion is instantaneously inserted into the interior of the bilayer. The formation of defects considerably lowers the free energy barrier ru transfer of the ion across the bilayer and, consequently, increases the permeabilities of the membrane to ions, compared to the rigid, planar structure, by approximately 14 orders of magnitude. Our results have implications for drug delivery using liposomes and peptide insertion into membranes. C1 UNIV CALIF SAN FRANCISCO, DEPT PHARMACEUT CHEM, SAN FRANCISCO, CA 94143 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 70 TC 114 Z9 114 U1 4 U2 16 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD JUL 17 PY 1996 VL 118 IS 28 BP 6580 EP 6587 DI 10.1021/ja9540381 PG 8 WC Chemistry, Multidisciplinary SC Chemistry GA UX673 UT WOS:A1996UX67300007 PM 11539569 ER PT J AU Andras, MT Hepp, AF Fanwick, PE Martuch, RA Duraj, SA Gordon, EM AF Andras, MT Hepp, AF Fanwick, PE Martuch, RA Duraj, SA Gordon, EM TI 4-methylpyridinium hydrogen sulfide SO ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS LA English DT Article AB 4-Methylpyridinium hydrogen sulfide, C6H7NH+.HS-, was obtained as a by-product of the reaction between GaCl3 and thioglycolic acid in a LC-methylpyridine solution, The compound consists of heterocyclic C6H7NH+ cationic rings and HS- anions. Both the C6H7NH+ cation and the HS- anion lie on crystallographic mirror planes with the N, S, two C and two H atoms positioned in the planes. The H atom of the HS- anion was not located. C1 PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. CLEVELAND STATE UNIV,DEPT CHEM,CLEVELAND,OH 44115. WILBERFORCE UNIV,WILBERFORCE,OH 45384. RP Andras, MT (reprint author), NASA,LEWIS RES CTR,PHOTOVOLTA BRANCH,MS 302-1,CLEVELAND,OH 44135, USA. NR 11 TC 5 Z9 5 U1 0 U2 0 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0108-2701 J9 ACTA CRYSTALLOGR C JI Acta Crystallogr. Sect. C-Cryst. Struct. Commun. PD JUL 15 PY 1996 VL 52 BP 1701 EP 1702 DI 10.1107/S0108270196000078 PN 7 PG 2 WC Chemistry, Multidisciplinary; Crystallography SC Chemistry; Crystallography GA VB092 UT WOS:A1996VB09200045 ER PT J AU Pryor, WR Barth, CA Hord, CW Stewart, AIF Simmons, KE Gebben, JJ McClintock, WE Lineaweaver, S Ajello, JM Tobiska, WK Naviaux, KL Edberg, SJ White, OR Sandel, BR AF Pryor, WR Barth, CA Hord, CW Stewart, AIF Simmons, KE Gebben, JJ McClintock, WE Lineaweaver, S Ajello, JM Tobiska, WK Naviaux, KL Edberg, SJ White, OR Sandel, BR TI Latitude variations in interplanetary Lyman-alpha data from the Galileo EUVS modeled with solar He 1083 nm images SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ULTRAVIOLET SPECTROMETER EXPERIMENT; VENUS; MAXIMUM; FLUX AB Observations of interplanetary Lyman-alpha obtained by the Galileo Extreme Ultraviolet Spectrometer (EUVS) experiment near solar maximum in 1990 show a distinct migration in the upwind brightness maximum from 36+/-5 degrees N to 6+/-5 degrees N ecliptic latitude over a period of several months. Our earlier models based on solar Lyman-alpha flux proxies appropriate for use in the ecliptic plane (Pryer et al., 1992; Ajello et al., 1994) capture the solar rotation effects present in the data, but do not reproduce this latitude migration. We introduce a new type of model that uses He 1083 nm images to produce a proxy for Lyman-alpha as a function of both solar longitude and latitude. This model reproduces the observed latitude migration of the Lyman-alpha brightness maximum. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RP Pryor, WR (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,CAMPUS BOX 392,BOULDER,CO 80309, USA. NR 14 TC 24 Z9 24 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 15 PY 1996 VL 23 IS 15 BP 1893 EP 1896 DI 10.1029/96GL01978 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UY592 UT WOS:A1996UY59200001 ER PT J AU Callis, LB Boughner, RE Baker, DN Mewaldt, RA Blake, JB Selesnick, RS Cummings, JR Natarajan, M Mason, GM Mazur, JE AF Callis, LB Boughner, RE Baker, DN Mewaldt, RA Blake, JB Selesnick, RS Cummings, JR Natarajan, M Mason, GM Mazur, JE TI Precipitating electrons: Evidence for effects on mesospheric odd nitrogen SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR AB Observations of electron fluxes made by the PET and LICA instruments aboard SAMPEX have been used with NO measurements made by HALOE aboard UARS to provide evidence of mesospheric and lower thermospheric NO formation due to precipitating electrons. Results indicate significant NO increases from 70 to 120 km which are associated with the occurrence of enhanced electron populations in the outer trapping regions of the magnetosphere, 2.5 less than or equal to L less than or equal to 7, which precipitate into the atmosphere. C1 UNIV COLORADO,LASP,BOULDER,CO 80303. CALTECH,SRL,PASADENA,CA 91125. AEROSP CORP,LOS ANGELES,CA 90009. SAIC,HAMPTON,VA 23666. UNIV MARYLAND,COLLEGE PK,MD 20742. RP Callis, LB (reprint author), NASA,LANGLEY RES CTR,ASD,HAMPTON,VA 23681, USA. NR 10 TC 39 Z9 40 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 15 PY 1996 VL 23 IS 15 BP 1901 EP 1904 DI 10.1029/96GL01787 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UY592 UT WOS:A1996UY59200003 ER PT J AU Callis, LB Baker, DN Natarajan, M Blake, JB Mewaldt, RA Selesnick, RS Cummings, JR AF Callis, LB Baker, DN Natarajan, M Blake, JB Mewaldt, RA Selesnick, RS Cummings, JR TI A 2-D model simulation of downward transport of NOy into the stratosphere: Effects on the 1994 austral spring O-3 and NOy SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE ATMOSPHERE; OZONE DEPLETION; SOLAR AB Simulations using SAMPEX and HALOE data suggest that NOy produced by thermospheric processes and by relativistic electron precipitation in the mesosphere and lower thermosphere have been important to stratospheric NOy and O-3 during the austral spring in 1994. The relative importance of the two NOy sources is discussed. The results are supported by an analysis of HALOE NOy and CH4 data during October 1994 and are in agreement with ATMOS NOy observations made in November 1994. C1 UNIV COLORADO,LASP,BOULDER,CO 80303. SAIC,HAMPTON,VA 23666. AEROSP CORP,LOS ANGELES,CA 90009. CALTECH,SRL,PASADENA,CA 91125. RP Callis, LB (reprint author), NASA,LANGLEY RES CTR,ASD,HAMPTON,VA 23681, USA. NR 18 TC 44 Z9 44 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 15 PY 1996 VL 23 IS 15 BP 1905 EP 1908 DI 10.1029/96GL01788 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UY592 UT WOS:A1996UY59200004 ER PT J AU Cho, JYN Jurgens, RF Slade, MA AF Cho, JYN Jurgens, RF Slade, MA TI High-resolution stratospheric dynamics measurements with the NASA/JPL Goldstone Solar System Radar SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CONVECTIVE STORMS; INFRASOUND; ATMOSPHERE; ARECIBO; WAVES AB We have used, for the first time that we are aware of, the NASA/JPL Goldstone planetary radar to study the Earth's atmosphere. With its high bandwidth and power, we were able to achieve a height resolution of 20 m, which is significantly better than the usual 150-m resolution for stratospheric radars. Here we discuss the observation of a very thin scattering layer that persisted over several hours at the same height just above the tropopause. We question the assumption of turbulent radar scatter based on the available evidence, and also investigate the two-minute oscillation observed in the vertical velocity. C1 NASA,JET PROPULS LAB,PASADENA,CA. RP Cho, JYN (reprint author), NATL ASTRON & IONOSPHERE CTR,ARECIBO OBSERV,POB 995,ARECIBO,PR 00613, USA. NR 12 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 15 PY 1996 VL 23 IS 15 BP 1909 EP 1912 DI 10.1029/96GL01570 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UY592 UT WOS:A1996UY59200005 ER PT J AU Dye, JE Baumgardner, D Gandrud, BW Drdla, K Barr, K Fahey, DW Delnegro, LA Tabazadeh, A Jonsson, HH Wilson, JC Loewenstein, M Podolske, JR Chan, KR AF Dye, JE Baumgardner, D Gandrud, BW Drdla, K Barr, K Fahey, DW Delnegro, LA Tabazadeh, A Jonsson, HH Wilson, JC Loewenstein, M Podolske, JR Chan, KR TI In-situ observations of an Antarctic polar stratospheric cloud: Similarities with Arctic observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AEROSOL; GROWTH; WATER AB Measured particle volumes in a type I polar stratospheric cloud near the Antarctic polar vortex during ASHOE/MAESA show that the onset of the cloud occurred near 193 K, 3 degrees colder than nitric acid trihydrate (NAT) saturation. The onset temperature, the smooth increase of volume with decreasing temperature, the inverse correlation of particle volume and enhanced NOy (HNO3 in the particles) with temperature, and comparisons of observations with an equilibrium model of ternary droplet growth all support the notion that much of this type I PSC was ternary solution droplets. This provides confirmation of previous findings in the northern hemisphere. However, the ternary model does not fit the observations in all regions. This may be due to the presence of some solid phase growth in agreement with impactor observations. C1 NOAA,AERON LAB,BOULDER,CO 80303. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV DENVER,DENVER,CO 80210. UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024. RP Dye, JE (reprint author), NATL CTR ATMOSPHER RES,POB 3000,BOULDER,CO 80307, USA. RI Fahey, David/G-4499-2013 OI Fahey, David/0000-0003-1720-0634 NR 15 TC 33 Z9 33 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 15 PY 1996 VL 23 IS 15 BP 1913 EP 1916 DI 10.1029/96GL01812 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UY592 UT WOS:A1996UY59200006 ER PT J AU Yu, ST Jiang, BN Liu, NS Wu, J AF Yu, ST Jiang, BN Liu, NS Wu, J TI Technical note: Simulation of an H-2/O-2 flame by the least-squares finite element method SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE LSFEM; reacting flows AB The aim of this paper is to use the least-squares finite element method to simulate a quasi-one-dimensional H-2/O-2 flame with comprehensive physical property models. C1 NASA,LEWIS RES CTR,OAI,INST COMPUTAT MECH & PROP,CLEVELAND,OH 44135. RP Yu, ST (reprint author), NASA,LEWIS RES CTR,NYMA SETAR TEAM,BROOKPARK,OH, USA. NR 10 TC 2 Z9 2 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD JUL 15 PY 1996 VL 23 IS 1 BP 65 EP 74 DI 10.1002/(SICI)1097-0363(19960715)23:1<65::AID-FLD398>3.0.CO;2-C PG 10 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA UW401 UT WOS:A1996UW40100005 ER PT J AU Sha, YG Su, CH Mazuruk, K Lehoczky, SL AF Sha, YG Su, CH Mazuruk, K Lehoczky, SL TI Thermal diffusivity and conductivity of Hg1-xZnxTe solids and melts SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID HG1-XCDXTE AB The thermal diffusivity of pseudobinary Hg1-xZnxTe solids and melts was measured by the laser flash method. The measured diffusivities for the solids of 0.10 less than or equal to x less than or equal to 0.30 are about 60% of that of the HgTe solid. Those for the melts rise rapidly with temperature but less so with increasing x. For x=0.30, the diffusivity of the melt is about one third of that of the HgTe melt. Using the calculated heat capacity data from the associated solution model and measured density values, the thermal conductivity for the pseudobinary Hg1-xZnxTe solids of 0.10 less than or equal to x less than or equal to 0.30 and for the melts of x = 0.10, 0.16, and 0.30 was determined. (C) 1996 American Institute of Physics. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. NR 15 TC 2 Z9 2 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUL 15 PY 1996 VL 80 IS 2 BP 752 EP 755 DI 10.1063/1.362917 PG 4 WC Physics, Applied SC Physics GA UX156 UT WOS:A1996UX15600020 ER PT J AU Neudeck, PG Fazi, C AF Neudeck, PG Fazi, C TI High-field fast-risetime pulse failures in 4H- and 6H-SiC pn junction diodes SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SILICON-CARBIDE; DEVICES; SI AB We report the observation of anomalous reverse breakdown behavior in moderately doped (2-3x10(17) cm(-3)) small-area micropipe-free 4H- and 6H-SiC pn junction diodes. When measured with a curve tracer, the diodes consistently exhibited very low reverse leakage currents and sharp repeatable breakdown knees in the range of 140-150 V. However, when subjected to single-shot reverse bias pulses (200 ns pulsewidth, 1 ns risetime), the diodes failed catastrophically at pulse voltages of less than 100 V. We propose a possible mechanism for this anomalous reduction in pulsed breakdown voltage relative to de breakdown voltage. This instability must be removed so that SiC high-field devices can operate with the same high reliability as silicon power devices. C1 USA,RES LAB,ADELPHI,MD 20783. RP Neudeck, PG (reprint author), NASA,LEWIS RES CTR,21000 BROOKPK RD,MS 77-1,CLEVELAND,OH 44135, USA. NR 21 TC 24 Z9 24 U1 0 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUL 15 PY 1996 VL 80 IS 2 BP 1219 EP 1225 DI 10.1063/1.362922 PG 7 WC Physics, Applied SC Physics GA UX156 UT WOS:A1996UX15600089 ER PT J AU Crawford, TD Schaefer, HF Lee, TJ AF Crawford, TD Schaefer, HF Lee, TJ TI On the energy invariance of open-shell perturbation theory with respect to unitary transformations of molecular orbitals SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID HARTREE-FOCK REFERENCE; CONFIGURATION-INTERACTION; TRIPLE EXCITATIONS; SPIN ORBITALS; GRADIENT; SYSTEMS; SINGLES AB A number of recently proposed single-reference open-shell perturbation theories based on a spin-restricted open-shell Hartree-Fock reference function are examined, with an emphasis on a consistent formalism within which the theories may be compared. In particular, the effect of unitary transformations among the molecular orbitals on the energy is discussed. Of the seven different perturbation theories examined here, the restricted Moller-Plesset theory, open-shell perturbation theory method 1, the method of Hubac and Carsky, Z-averaged perturbation theory, and invariant open-shell perturbation theory methods are found to be invariant to all types of rotations for which the reference wave function is unaffected, though all are invariant to transformations of a more limited nature. Explicit equations for the generalized invariant forms of each perturbation theory are presented, in order to provide working equations for extension of the theories to local correlation schemes or coupled-cluster perturbational corrections, among others. (C) 1996 American Institute of Physics. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Crawford, TD (reprint author), UNIV GEORGIA,CTR COMPUTAT QUANTUM CHEM,ATHENS,GA 30602, USA. RI Lee, Timothy/K-2838-2012; Crawford, Thomas/A-9271-2017 OI Crawford, Thomas/0000-0002-7961-7016 NR 35 TC 25 Z9 25 U1 1 U2 13 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUL 15 PY 1996 VL 105 IS 3 BP 1060 EP 1069 DI 10.1063/1.471951 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UW836 UT WOS:A1996UW83600020 ER PT J AU Liu, WT Tang, WQ Atlas, R AF Liu, WT Tang, WQ Atlas, R TI Responses of the tropical Pacific to wind forcing as observed by spaceborne sensors and simulated by an ocean general circulation model SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEA-LEVEL; VARIABILITY; STRESS; ECMWF; HEAT AB In this study, satellite observations, in situ measurements, and model simulations are combined to assess the oceanic response to surface wind forcing in the equatorial Pacific. The surface wind fields derived from observations by the spaceborne special sensor microwave imager (SSM/I) and from the operational products of the European Centre for Medium-Range Weather Forecasts (ECMWF) are compared. When SSM/I winds are used to force a primitive-equation ocean general circulation model (OGCM), they produce 3 degrees C more surface cooling than ECMWF winds for the eastern equatorial Pacific during the cool phase of an El Nino-Southern Oscillation event. The stronger cooling by SSM/I winds is in good agreement with measurements at the moored buoys and observations by the advanced very high resolution radiometer, indicating that SSM/I winds are superior to ECMWF winds in forcing the tropical ocean. In comparison with measurements from buoys, tide gauges, and the Geosat altimeter, the OGCM simulates the temporal variations of temperature, steric, and sea level changes with reasonable realism when forced with the satellite winds. There are discrepancies between model simulations and observations that are common to both wind forcing fields, one of which is the simulation of zonal currents; they could be attributed to model deficiencies. By examining model simulations under two winds, vertical heat advection and uplifting of the thermocline are found to be the dominant factors in the anomalous cooling of the ocean mixed layer. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP Liu, WT (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 34 TC 17 Z9 17 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 1996 VL 101 IS C7 BP 16345 EP 16359 DI 10.1029/96JC01347 PG 15 WC Oceanography SC Oceanography GA UX792 UT WOS:A1996UX79200006 ER PT J AU Boulanger, JP Fu, LL AF Boulanger, JP Fu, LL TI Evidence of boundary reflection of Kelvin and first-mode Rossby waves from TOPEX/POSEIDON sea level data SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID EQUATORIAL PACIFIC; EL-NINO; OCEAN; WIND; ENSO AB The TOPEX/POSEIDON sea level data lead to new opportunities to investigate some theoretical mechanisms suggested to be involved in the El Nino-Southern Oscillation phenomenon in the tropical Pacific ocean. In particular, we are interested in studying the western boundary reflection, a process crucial for the delayed action oscillator theory, by using the TOPEX/POSEIDON data from November 1992 to May 1995. We first projected the sea level data onto Kelvin and first-mode Rossby waves. Then we estimated the contribution of wind forcing to these waves by using a single baroclinic mode simple wave model forced by the ERS 1 wind data. Wave propagation was clearly observed with amplitudes well explained by the wind forcing in the ocean interior. Evidence of wave reflection was detected at both the western and eastern boundaries of the tropical Pacific ocean. At the eastern boundary, Kelvin waves were seen to reflect as first-mode Rossby waves during the entire period. The reflection efficiency (in terms of wave amplitude) of the South American coasts was estimated to be 80% of that of an infinite meridional wall. At the western boundary, reflection was observed in April-August 1993, in January-June 1994, and, later, in December 1994 to February 1995. Although the general roles of these reflection events in the variability observed in the equatorial Pacific ocean are not clear, the data suggest that the reflections in January-June 1994 have played a role in the onset of the warm conditions observed in late 1994 to early 1995. Indeed, during the January-June 1994 period, as strong downwelling first-mode Rossby waves reflected into downwelling Kelvin waves, easterly wind and cold sea surface temperature anomalies located near the date line weakened and eventually reversed in June-July 1994. The presence of the warm anomalies near the date line then favored convection and westerly wind anomalies that triggered strong downwelling Kelvin waves propagating throughout the basin simultaneously with the beginning of the 1994-1995 warm conditions. RP Boulanger, JP (reprint author), CALTECH,JET PROP LAB,MS 300-323,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 21 TC 46 Z9 46 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 1996 VL 101 IS C7 BP 16361 EP 16371 DI 10.1029/96JC01282 PG 11 WC Oceanography SC Oceanography GA UX792 UT WOS:A1996UX79200007 ER PT J AU Winebrenner, DP Holt, B Nelson, ED AF Winebrenner, DP Holt, B Nelson, ED TI Observation of autumn freeze-up in the Beaufort and Chukchi Seas using the ERS 1 synthetic aperture radar SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SATELLITE MICROWAVE DATA; ICE COVER; BACKSCATTER SIGNATURES; IMAGERY; MODEL; PATTERNS AB We present observations of the transition in sea ice backscattering signatures from late summer into early winter in the Beaufort and Chukchi Seas during 1991 and 1992, using data from the ERS 1 synthetic aperture radar (SAR). We employ both analyzed surface temperature fields and direct observations of near-surface temperature from drifting buoys. Consistent with previous surface-based observations, backscattering from sea ice surviving at the end of summer increases strongly and rapidly when temperatures fall below freezing for the final time in the autumn, apparently because of increased volume scattering from bubbles in the upper part of the ice. Areally averaged backscattering sometimes overshoots typical winter multiyear ice values by 1-2 dB, before settling back over a period of approximately a week. The backscattering-temperature link forms a sufficient basis for an algorithm to estimate retrospectively, from time series of SAR images, the date of freeze-up (defined here to be the date on which all liquid water in the bubbly upper layer of surviving sea ice freezes and remains frozen for the duration of the ensuing autumn and winter). We present a prototype algorithm and use it to estimate freeze-up dates in nine Lagrangian cells in the Beaufort Sea during the autumn of 1992. We observe a 12-day spread in freeze-up dates between latitudes of approximately 73 degrees N and 82 degrees N, with dates in the northernmost cells of August 29-30 and those in the southernmost cells of September 7. Two cells at latitudes of 75 degrees N-77 degrees N appear to freeze-up earlier than cells further north but present uncertainties limit the significance of this observation. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Winebrenner, DP (reprint author), UNIV WASHINGTON,APPL PHYS LAB,COLL OCEAN & FISHERY SCI,1013 NE 40TH ST,SEATTLE,WA 98105, USA. NR 31 TC 22 Z9 23 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 1996 VL 101 IS C7 BP 16401 EP 16419 DI 10.1029/96JC01292 PG 19 WC Oceanography SC Oceanography GA UX792 UT WOS:A1996UX79200011 ER PT J AU Hoge, FE Lyon, PE AF Hoge, FE Lyon, PE TI Satellite retrieval of inherent optical properties by linear matrix inversion of oceanic radiance models: An analysis of model and radiance measurement errors SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID REMOTE-SENSING REFLECTANCE; DISSOLVED ORGANIC-MATTER; ABSORPTION-SPECTRA; PHYTOPLANKTON PIGMENTS; BIOGENOUS MATTER; NATURAL-WATERS; SARGASSO SEA; COLOR; CHLOROPHYLL; COEFFICIENT AB The linear summability of inherent optical properties (IOPs) is exploited to provide matrix equations for retrieval of phytoplankton absorption, dissolved organic matter, and constituent backscatter. Spectral models for the phytoplankton pigment absorption coefficient, chromophoric dissolved organic matter (CDOM) absorption coefficient, and total constituent backscatter (TCB) coefficient are first used to calculate 5 x 10(5) water-leaving spectral radiances for a wide range of normally distributed IOP values at 410, 490, and 555 nm. Then, the spectral radiances are inverted to simultaneously provide phytoplankton pigment absorption coefficient, CDOM absorption coefficient, and total constituent backscatter coefficient on a pixel-by-pixel basis to demonstrate that (1) matrix inversion is very rapid and well conditioned, (2) the IOPs are exactly determined when the water-leaving radiances and IOP spectral models are error free, (3) for equal radiance errors sequentially occurring in one of three sensor bands, phytoplankton pigment retrieval errors are generally higher than CDOM and TCB coefficient errors, (4) retrieval errors for ail the IOPs are strongly dependent on phytoplankton pigment spectral model Gaussian width errors, (5) phytoplankton pigment absorption and CDOM absorption retrieval errors are more sensitive to CDOM spectral slope errors than the TCB coefficient retrievals, and (6) TCB wavelength-ratio-exponent errors produce less impact on the phytoplankton absorption coefficient retrieval than upon the CDOM absorption or the TCB coefficient retrievals. C1 EG&G WASHINGTON ANALYT SERV INC,WALLOPS FLIGHT FACIL,WALLOPS ISL,VA 23337. RP Hoge, FE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,WALLOPS FLIGHT FACIL,BLDG N-159,WALLOPS ISL,VA 23337, USA. NR 40 TC 126 Z9 129 U1 2 U2 17 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUL 15 PY 1996 VL 101 IS C7 BP 16631 EP 16648 DI 10.1029/96JC01414 PG 18 WC Oceanography SC Oceanography GA UX792 UT WOS:A1996UX79200027 ER PT J AU Marcus, SL Ghil, M Dickey, JO AF Marcus, SL Ghil, M Dickey, JO TI The extratropical 40-day oscillation in the UCLA general circulation model .2. Spatial structure SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID ATMOSPHERIC ANGULAR-MOMENTUM; TROPICAL INTRASEASONAL OSCILLATIONS; MIDLATITUDE INTERACTION; SEASONAL-VARIATIONS; GLOBAL ATMOSPHERE; BAROTROPIC MODEL; NORTHERN WINTER; TIME SCALES; CONVECTION; FLUCTUATIONS AB Intraseasonal oscillations in a 3-yr, perpetual-January simulation are examined using a version of the UCLA GCM that produces no self-sustained Madden-Julian oscillation in the Tropics. A robust, 40-day oscillation is found to arise in the model's Northern Hemisphere (NH) extratropics when standard topography is present. Part I of this study addressed the zonally averaged component of the GCM oscillation, manifested in wind- and pressure-induced variations in atmospheric angular momentum (AAM). The focus here is on the spatial features of the oscillation as manifested in the variability of the 500-mb height field. A standing, wavenumber-two pattern is found in the NH extratropics, which undergoes tilted-trough vacillation in conjunction with the model's AAM oscillation. High (low) values of AAM are associated with low (high) 500-mb heights over the northeast Pacific and Atlantic Oceans; the two centers' of action slightly different frequencies give rise to a long-period modulation (of about 300 days) in the amplitude of the intraseasonal oscillation. Global correlations with the leading empirical orthogonal functions of the NH extratropical 500-mb height field show northeast-southwest teleconnection patterns extending into the Tropics, similar to those found in observational studies. The zonally averaged latent heating in the Tropics exhibits no intraseasonal periodicity, but a 39-day oscillation is found in cumulus precipitation over the western Indian Ocean. The latter shows significant coherence with EOF 1 but is absent in three shorter no-mountain experiments (see Part I), indicating that it may be remotely forced by the intraseasonal oscillation that arises in the model's NH extratropics only in the standard-topography experiment. C1 UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. ECOLE NORMALE SUPER,DEPT TERRE ATMOSPHERE OCEAN,F-75231 PARIS,FRANCE. RP Marcus, SL (reprint author), CALTECH,JET PROP LAB,SPACE GEODET SCI & APPLICAT GRP,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 67 TC 18 Z9 18 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD JUL 15 PY 1996 VL 53 IS 14 BP 1993 EP 2014 DI 10.1175/1520-0469(1996)053<1993:TEDOIT>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UZ736 UT WOS:A1996UZ73600004 ER PT J AU Grasso, D Kolb, EW AF Grasso, D Kolb, EW TI Cosmological bounds to the magnetic moment of heavy tau neutrinos SO PHYSICAL REVIEW D LA English DT Article ID PRIMORDIAL NUCLEOSYNTHESIS; UPPER LIMIT; DARK-MATTER; MASS; PLASMA; DECAYS AB The magnetic moment of tau neutrinos in the MeV mass range may he large enough to modify the cosmological freeze-out calculation and determine the tau-neutrino relic density. In this paper we reexamine such a possibility, We calculate the evolution and freeze-our of the tau-neutrino number density as a function of its mass and magnetic moment. We then determine its relic density; then calculate its effect upon primordial nucleo-synthesis including previously neglected effects. C1 UNIV STOCKHOLM,DEPT PHYS,S-11346 STOCKHOLM,SWEDEN. FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP Grasso, D (reprint author), UNIV UPPSALA,DEPT THEORET PHYS,BOX 803,S-75108 UPPSALA,SWEDEN. RI Grasso, Dario/I-2440-2012 OI Grasso, Dario/0000-0001-7761-7242 NR 29 TC 5 Z9 5 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 JUL 15 PY 1996 VL 54 IS 2 BP 1374 EP 1378 DI 10.1103/PhysRevD.54.1374 PG 5 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA UY733 UT WOS:A1996UY73300016 ER PT J AU Guelachvili, G Birk, M Borde, CJ Brault, JW Brown, LR Carli, B Cole, ARH Evenson, KM Fayt, A Hausamann, D Johns, JWC Kauppinen, J Kou, Q Maki, AG Rao, KN Toth, RA Urban, W Valentin, A Verges, J Wagner, G Wappelhorst, MH Wells, JS Winnewisser, BP Winnewisser, M AF Guelachvili, G Birk, M Borde, CJ Brault, JW Brown, LR Carli, B Cole, ARH Evenson, KM Fayt, A Hausamann, D Johns, JWC Kauppinen, J Kou, Q Maki, AG Rao, KN Toth, RA Urban, W Valentin, A Verges, J Wagner, G Wappelhorst, MH Wells, JS Winnewisser, BP Winnewisser, M TI High resolution wavenumber standards for the infrared (Reprinted from Pure Appl Chem, Vol 68, pg 193-208, 1996) SO SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY LA English DT Reprint ID HETERODYNE FREQUENCY MEASUREMENTS; (CO)-C-12-O-16 LASER TRANSITIONS; ACCURATE ROTATIONAL-CONSTANTS; CARBONYL SULFIDE; LINE POSITIONS; MOLECULAR-CONSTANTS; MU-M; CALIBRATION TABLES; FUNDAMENTAL-BAND; DIODE-LASER AB The calibration of high resolution infrared spectra is generally more precise than accurate. This is the case even when they are recorded with Fourier transform interferometers. The present document aims at improving the accuracy of wavenumber measurements in the infrared by recommending a selection of spectral lines as wavenumber standards for absolute calibration in the range from about 4 to about 7000 cm(-1). The uncertainties of these wavenumber standards range from +/-1 x 10(-3) to +/-1 x 10(-6) cm(-1). Sources of frequency standards, on which the wavenumber determinations are based, are also given. C1 DLR,INST OPTOELECTR,D-82234 WESSELING,GERMANY. UNIV PARIS 13,PHYS LASERS LAB,F-93430 VILLETANEUSE,FRANCE. NOAA,AERON LAB,BOULDER,CO 80303. CALTECH,JET PROP LAB,PASADENA,CA 91109. CNR,IST RIC ONDE ELETTROMAGNET,I-50127 FLORENCE,ITALY. UNIV WESTERN AUSTRALIA,SCH CHEM,NEDLANDS,WA 6009,AUSTRALIA. NATL INST STAND & TECHNOL,DIV TIME & FREQUENCY,BOULDER,CO 80303. UNIV CATHOLIQUE LOUVAIN,MOL SPECT LAB,B-1348 LOUVAIN,BELGIUM. NATL RES COUNCIL CANADA,STEACIE INST MOLEC SCI,OTTAWA,ON K1A 0R6,CANADA. TURKU UNIV,DEPT APPL PHYS,FIN-20500 TURKU,FINLAND. UNIV WASHINGTON,DEPT CHEM,SEATTLE,WA 98195. OHIO STATE UNIV,DEPT PHYS,COLUMBUS,OH 43210. UNIV BONN,INST ANGEW PHYS,D-53115 BONN,GERMANY. UNIV PARIS 06,CNRS,UPR 136,PHYS MOLEC LAB,F-75252 PARIS,FRANCE. LAB AIMEE COTTON,F-91405 ORSAY,FRANCE. UNIV GIESSEN,PHYS CHEM INST,D-35392 GIESSEN,GERMANY. RP Guelachvili, G (reprint author), UNIV PARIS 11,CNRS,PHYS MOLEC LAB,UPR 136,BATIMENT 350,F-91405 ORSAY,FRANCE. NR 96 TC 10 Z9 10 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0584-8539 J9 SPECTROCHIM ACTA A JI Spectroc. Acta Pt. A-Molec. Biomolec. Spectr. PD JUL 15 PY 1996 VL 52 IS 7 BP 717 EP 732 DI 10.1016/0584-8539(96)01717-5 PG 16 WC Spectroscopy SC Spectroscopy GA UV249 UT WOS:A1996UV24900001 ER PT J AU McBeath, MK Shaffer, DM Kaiser, MK AF McBeath, MK Shaffer, DM Kaiser, MK TI On catching fly balls - Reply SO SCIENCE LA English DT Article ID CURVATURE C1 NASA,AMES RES CTR,HUMAN & SYST TECHNOL BRANCH,MOFFETT FIELD,CA 94035. RP McBeath, MK (reprint author), KENT STATE UNIV,DEPT PSYCHOL,KENT,OH 44242, USA. RI Shaffer, Dennis/F-5300-2013 NR 17 TC 16 Z9 17 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUL 12 PY 1996 VL 273 IS 5272 BP 258 EP 260 DI 10.1126/science.273.5272.258 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UW787 UT WOS:A1996UW78700048 PM 17830727 ER PT J AU Lord, SD Hollenbach, DJ Haas, MR Rubin, RH Colgan, SWJ Erickson, EF AF Lord, SD Hollenbach, DJ Haas, MR Rubin, RH Colgan, SWJ Erickson, EF TI Interstellar properties of a dual nuclear starburst: Far-infrared spectroscopy of M82 SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; galaxies, abundances; galaxies, individual (M82); galaxies, ISM; galaxies, starburst; infrared, galaxies ID H-II REGIONS; INITIAL MASS FUNCTION; PHOTODISSOCIATION REGIONS; GALAXY M82; LINE EMISSION; CONTINUUM OBSERVATIONS; MOLECULAR CLOUDS; 158 MICRON; GAS; RADIO AB We have measured [O I] 63 mu m and [Si II] 35 mu m in the central 44 '' (700 pc) of the starburst galaxy M82. The luminosities in these transitions are each similar to 0.1% of the bolometric luminosity. We model the [O I] in M82 as arising from warm neutral gas photodissociated by far-ultraviolet (FUV) flux from OB stars, while most of the [Si II] emission arises from associated H II regions. The gas-phase Si/H abundance ratio is found to be similar to 1.5 x 10(-5) or about 3 times greater than that seen in galactic nebulae, where silicon is mostly bound up in grains. The enrichment is probably caused by the partial destruction of silicate grains by fast supernovae-driven shocks. The [O I] 63 mu m and the [Si II] 35 mu m spectrum both show an asymmetric line profile indistinguishable in shape from those of the [O III] 52 and 88 mu m and [N III] 57 mu m lines measured previously in M82. We detect two distinct velocity components, which we attribute to emission from two regions associated with the molecular gas concentrations located 190 pc (12 '') on either side of the nucleus. We model separately the two emission lobes and derive the cloud conditions in these two regions. The derived properties suggest that the clouds in these lobes are small, r(cl)similar to 0.4-1.0 pc, have warm, T similar to 230 K, neutral gas surfaces, and are concentrated with volume filling factors of similar to 0.1 and area filling factors of approximately seven to 20. Together, the two lobes, each of diameter similar to 125 pc (similar to 8 ''), are characterized by a large number, similar to 3 x 10(5), of similar to 600 M(.) clouds with surface gas densities of similar to 10(4) cm(-3) and with pressures of P/k similar to 3 x 10(6) cm(-3) K, illuminated by FUV fluxes similar to 10(3) times the average local interstellar value for the Milky Way. These highly pressurized clouds are held in pressure equilibrium by the surrounding H II regions and the hot intercloud medium. The clouds cannot sustain the nuclear starburst long. The intense FUV fluxes have already photodissociated about 10% of the molecular gas, and the combined effects of fragmentation, photoionization, and photodissociation caused by the massive stars will soon destroy the natal molecular environment. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Lord, SD (reprint author), CALTECH,IPAC,M-S 100-22,PASADENA,CA 91125, USA. RI Colgan, Sean/M-4742-2014 NR 82 TC 68 Z9 68 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1996 VL 465 IS 2 BP 703 EP 716 DI 10.1086/177455 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV063 UT WOS:A1996UV06300020 ER PT J AU Maran, SP Crenshaw, DM Mushotzky, RF Reichert, GA Carpenter, KG Smith, AM Hutchings, JB Weymann, RJ AF Maran, SP Crenshaw, DM Mushotzky, RF Reichert, GA Carpenter, KG Smith, AM Hutchings, JB Weymann, RJ TI Hubble Space Telescope observations of the Seyfert galaxy NGC 3783: Discovery of variable C IV absorption SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, individual (NGC 3783); galaxies, Seyfert; ultraviolet, galaxies ID QUASI-STELLAR OBJECTS; BROAD-LINE REGION; DETAILED OBSERVATIONS; NGC-3516; NGC-4151; IUE; SPECTRUM; EMISSION; NGC-5548 AB We have discovered variable absorption lines in HST spectra of the Seyfert 1 galaxy NGC 3783. C IV lambda lambda 1548.2, 1550.8 absorption is present in an FOS spectrum on 1992 July 27 and a GHRS spectrum on 1994 January 16 at a radial velocity of -450 km s(-1) relative to the emission-line peak, but there is no evidence for absorption in a GHRS spectrum on 1993 February 5. A GHRS spectrum on 1993 February 21, obtained just 16 days after the spectrum with no detectable C IV absorption, shows strong N V lambda lambda 1238.8, 1242.8 absorption lines, also at a radial velocity of -450 km s(-1). The observations place constraints on the two types of models for absorption-line variability: bulk motion into the line of sight, and variable ionization of gas already in the line of sight. C1 NASA,GODDARD SPACE FLIGHT CTR,SPACE SCI DIRECTORATE,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. DOMINION ASTROPHYS OBSERV,VICTORIA,BC V8X 4M6,CANADA. CARNEGIE INST WASHINGTON OBSERV,PASADENA,CA 91101. RP Maran, SP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH RESOLUT SPECTOG INVEST DEFINIT TEAM,GREENBELT,MD 20771, USA. RI Carpenter, Kenneth/D-4740-2012 NR 25 TC 27 Z9 27 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1996 VL 465 IS 2 BP 733 EP 737 DI 10.1086/177457 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV063 UT WOS:A1996UV06300022 ER PT J AU Israel, FP Maloney, PR Geis, N Herrmann, F Madden, SC Poglitsch, A Stacey, GJ AF Israel, FP Maloney, PR Geis, N Herrmann, F Madden, SC Poglitsch, A Stacey, GJ TI C+ emission from the magellanic clouds .1. The bright H II region complexes N159 and N160 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, ISM; H II regions; infrared, galaxies; Magellanic Clouds ID PHOTODISSOCIATION REGIONS; MOLECULAR CLOUDS; 158 MICRON; STAR FORMATION; GALAXIES; LINE; CO; CARBON; GAS; MODEL AB We have mapped the [C II] 158 mu m line toward the bright Large Magellanic Cloud H II regions N160 and N159. Both H II region/molecular cloud complexes are associated with extended clouds of C+. Comparison with CO observations of similar resolution shows that in both complexes peak 158 mu m emission occurs at the interfaces of the H II region and the associated molecular clouds, while more diffuse extended 158 mu m emission covers the entire molecular cloud complexes. Including the results on 30 Dor published elsewhere, the ratio of [C II] to CO intensities differs from cloud to cloud over 3 orders of magnitude, presumably reflecting evolutionary differences in cloud structure. The ratio of 158 mu m to far-infrared intensities also shows some variation, but over a much smaller range. It is typically around 1% and considerably higher than in Galactic clouds and in most galactic nuclei. Thus, at least on spatial scales of tens of parsecs, the intensity of 158 mu m emission correlates reasonably well, but not perfectly, with the infrared continuum intensity and very poorly with the CO intensity. The observed 158 mu m emission appears to be optically thin, implying minimum column densities N-H(min) = 3 x 10(21) cm(-2). In contrast to Galactic objects, in three of the four clouds observed, the total mass of the photon-dominated region (PDR) is a significant fraction of the total complex mass, although not to the extreme extent deduced for 30 Dor. The relative morphologies of [C II], CO, and far-infrared emission, as well as derived properties such as the high PDR-to-molecular mass ratios and the high photoelectric heating efficiencies characterizing the observed clouds, can be understood as the result of the lower metallicity and lower dust-to-gas ratio in the Large Magellanic Cloud relative to those in the Galaxy. This causes the cloud volume in which CO is abundant to shrink while simultaneously increasing the PDR volume; in addition, it produces a lower mean UV radiation field in the PDR zone by increasing the UV photon mean free path lengths, resulting in greater geometric dilution of the radiation held. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. MAX PLANCK INST EXTRATERR PHYS,GARCHING,GERMANY. CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853. RP Israel, FP (reprint author), STERREWACHT LEIDEN,POB 9513,2300 RA LEIDEN,NETHERLANDS. NR 46 TC 90 Z9 90 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1996 VL 465 IS 2 BP 738 EP 747 DI 10.1086/177458 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV063 UT WOS:A1996UV06300023 ER PT J AU Magnani, L Caillault, JP Hearty, T Stauffer, J Schmitt, JHMM Neuhauser, R Verter, F Dwek, E AF Magnani, L Caillault, JP Hearty, T Stauffer, J Schmitt, JHMM Neuhauser, R Verter, F Dwek, E TI A search for star formation in the translucent cloud MBM 40 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, clouds; ISM, individual (MBM 40); ISM, molecules; radio lines, ISM; stars, formation; stars, pre-main-sequence; X-rays, stars ID LATITUDE MOLECULAR CLOUDS; T-TAURI STARS; MEDIUM SENSITIVITY SURVEY; HIGH GALACTIC LATITUDES; X-RAY SURVEY; CIRRUS CLOUDS; DARK CLOUDS; NH3 OBSERVATIONS; INFRARED CIRRUS; HIGH-VELOCITY AB The star formation status of the translucent high-latitude molecular cloud, MBM 40, is explored through analysis of radio, infrared, optical, and X-ray data. With a peak visual extinction of 1 to 2 mag, MBM 40 is an example of a high-latitude cloud near the diffuse/translucent demarcation. However, unlike most translucent clouds, MBM 40 exhibits a compact morphology and a kinetic energy-to-gravitational potential energy ratio near unity. Our radio data, encompassing the CO (J = 1-0), CS (J = 2-1), and H2CO 1(11)-1(10) spectral line transitions, reveal that the cloud contains a ridge of molecular gas with n greater than or equal to 10(3) cm(-3). In addition, the molecular data, together with IRAS data, indicate that the mass of MBM 40 is similar to 40 M.. In light of the ever-increasing number of recently formed stars far from any dense molecular clouds or cores, we searched the environs of MBM 40 for any trace of recent star formation. We used the ROSAT All-Sky Survey X-ray data and a ROSAT PSPC pointed observation toward MBM 40 to identify 33 stellar candidates with properties consistent with pre-main-sequence (PMS) stars. Follow-up optical spectroscopy of the candidates with V < 15.5 was conducted with the 1.5 m Fred Lawrence Whipple Observatory telescope in order to identify signatures of T Tauri or pre-main-sequence stars (such as the Li 6708 Angstrom resonance line). Since none of our optically observed candidates display standard PMS signatures, we conclude that MBM 40 displays no evidence of recent or ongoing star formation. The absence of high-density molecular cores in the cloud and the relatively low column density compared to star-forming interstellar clouds may be the principal reasons that MBM 40 is devoid of star formation. More detailed comparison between this cloud and other, higher extinction translucent and dark clouds may elucidate the necessary initial conditions for the onset of low-mass star formation. C1 HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Magnani, L (reprint author), UNIV GEORGIA,DEPT PHYS & ASTRON,ATHENS,GA 30602, USA. NR 85 TC 13 Z9 13 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1996 VL 465 IS 2 BP 825 EP 839 DI 10.1086/177466 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV063 UT WOS:A1996UV06300031 ER PT J AU Nel, HI Arzoumanian, Z Bailes, M Brazier, KTS DAmico, N Esposito, JA Fichtel, CE Fierro, JM Hunter, SD Johnston, S Kanbach, G Kaspi, VM Kniffen, DA Lin, YC Lyne, AG Manchester, RN Mattox, JR MayerHasselwander, HA Merck, M Michelson, PF Nice, DJ Nolan, PL Ramanamurthy, PV Taylor, JH Thompson, DJ Westbrook, C AF Nel, HI Arzoumanian, Z Bailes, M Brazier, KTS DAmico, N Esposito, JA Fichtel, CE Fierro, JM Hunter, SD Johnston, S Kanbach, G Kaspi, VM Kniffen, DA Lin, YC Lyne, AG Manchester, RN Mattox, JR MayerHasselwander, HA Merck, M Michelson, PF Nice, DJ Nolan, PL Ramanamurthy, PV Taylor, JH Thompson, DJ Westbrook, C TI EGRET high-energy gamma-ray pulsar studies .3. A survey SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, observations; pulsars, general; surveys AB The 3.5 yr database of the Energetic Gamma Ray Experiment Telescope (EGRET) on board the Compton Gamma Ray Observatory has been surveyed for gamma-ray emission from all known spin-powered pulsars. Using contemporaneous timing solutions, upper limits on pulsed emission were obtained for 350 pulsars. Limits to unpulsed gamma radiation were obtained for all cataloged pulsars. No new pulsar detections have been found, although there is evidence for localized excesses at the positions of a few of these pulsars. No significant correlation was, however, found between E/d(2) and the sources of such unpulsed excesses. A number of models predict the relative gamma-ray luminosity from pulsars as a function of measurable pulsar parameters. By fitting these models to the six detected pulsars above 100 MeV, the functional form of models are tested, and we find that the luminosity does not scale with the pulsar parameters as predicted. Furthermore, some flux upper limits derived here appear to contradict the model predictions. This seems to indicate that the current models of gamma-ray pulsars are still incomplete. C1 PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2006,AUSTRALIA. MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. UNIV PALERMO,INST FIS,I-40126 BOLOGNA,ITALY. CNR,INST RADIOASTRON,I-40126 BOLOGNA,ITALY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. STANFORD UNIV,WW HANSEN EXPTL PHYS LAB,STANFORD,CA 94305. STANFORD UNIV,DEPT PHYS,STANFORD,CA 94305. UNIV SYDNEY,RES CTR THEORET ASTROPHYS,SYDNEY,NSW 2006,AUSTRALIA. CALTECH,IPAC,PASADENA,CA 91125. HAMPDEN SYDNEY COLL,DEPT PHYS,HAMPDEN SYDNEY,VA 23943. UNIV MANCHESTER,DEPT PHYS,JODRELL BANK,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. UNIV MARYLAND,ASTRON PROJECT,COLLEGE PK,MD 20740. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. RP Nel, HI (reprint author), POTCHEFSTROOM UNIV CHRISTIAN HIGHER EDUC,DEPT PHYS,SPACE RES UNIT,POTCHEFSTROOM 2520,SOUTH AFRICA. RI Nolan, Patrick/A-5582-2009; D'Amico, Nichi/A-5715-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 34 TC 48 Z9 48 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1996 VL 465 IS 2 BP 898 EP 906 DI 10.1086/177473 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV063 UT WOS:A1996UV06300038 ER PT J AU Boroson, B McCray, R Kallman, T Nagase, F AF Boroson, B McCray, R Kallman, T Nagase, F TI Pulsations in the ultraviolet and X-ray spectra of Vela X-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars, individual (Vela X-1); stars, oscillations; X-rays, stars ID CIRCUMSTELLAR MATTER; STELLAR WINDS; 4U 0900-40; VARIABILITY; HD-77581; SYSTEM; PHASE AB In simultaneous observations with the Faint Object Spectrograph aboard the Hubble Space Telescope and the large-area counters aboard Ginga, we obtained time-resolved ultraviolet and X-ray spectra of the X-ray binary HD 77581/4U 0900 - 40 (Vela X-1) during inferior conjunction of the X-ray source. We detected pulsations at the 283.33 s X-ray pulse period in the absorption lines Si IV lambda 1402 and N V lambda lambda 1238, 1242. The pulse amplitudes in the UV lines were similar to 3%. The profile of the pulsed UV intensity in the Si IV absorption line resembled that of the soft X-rays, while that in the N V line was anticorrelated with the profile of the hard X-ray pulsations. The effect is probably due to photoionization of Si IV and N IV in the stellar wind of HD 77581 by the rotating beam of Vela X-1. C1 GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. INST SPACE & ASTRONAUT SCI,SAGAMIHARA,KANAGAWA 229,JAPAN. RP Boroson, B (reprint author), UNIV COLORADO,JOINT INST LAB ASTROPHYS,CAMPUS BOX 440,BOULDER,CO 80309, USA. NR 25 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1996 VL 465 IS 2 BP 940 EP 944 DI 10.1086/177477 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV063 UT WOS:A1996UV06300042 ER PT J AU Espey, B Keenan, FP McKenna, FC Feibelman, WA Aggarwal, KM AF Espey, B Keenan, FP McKenna, FC Feibelman, WA Aggarwal, KM TI Ne v and Ne vi lines in the ultraviolet spectrum of the symbiotic star RR Telescopii SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic processes; binaries, symbiotic; stars, individual (RR Telescopii); ultraviolet, stars ID B-LIKE IONS; SOLAR EMISSION; O-IV; TRANSITIONS; DIAGNOSTICS; NEBULAE; RATIOS; LIST; IUE; TEL AB New theoretical Ne VI] electron density-sensitive ratios are presented for the intercombination transitions R(1) = I(1006.1 Angstrom)/I(999.6 degrees) and R(2) = I(1010.6 Angstrom)/I(999.6 Angstrom). Temperature-sensitive ratios are also given for the Ne V] ratio R = I(1137.0 Angstrom)/I(1574.8 Angstrom). We discuss the potential usefulness of these line ratios for studying hot gas and apply them to the case of the symbiotic system RR Telescopii. Using far-UV data that has recently been acquired with the Hopkins Ultraviolet Telescope, we conclude that the Ne V and Ne VI emission in RR Tel is due to photoionization, with the temperature and density of the emitting region being approximately T-e similar or equal to 18,000 K and N-e similar or equal to 10(6) cm(-3), respectively. These results are similar to those estimated using other high ionization line diagnostics of the nebular material, such as O V I(1371 Angstrom)/I(1644 Angstrom) and Ne IV] I(1602 Angstrom)/I(2423 Angstrom). Although these Ne V] and Ne VI] lines have been used as diagnostics for solar physics, we believe that this is the first instance in which they have been applied to another astrophysical object. C1 QUEENS UNIV BELFAST,DEPT PURE & APPL PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV DELHI,DEPT PHYS & ASTROPHYS,DELHI 110007,INDIA. UNIV PITTSBURGH,DEPT PHYS & ASTRON,PITTSBURGH,PA 15260. RP Espey, B (reprint author), JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,CTR ASTROPHYS SCI,BALTIMORE,MD 21218, USA. OI Espey, Brian/0000-0002-2457-1380 NR 31 TC 12 Z9 12 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1996 VL 465 IS 2 BP 965 EP 971 DI 10.1086/177481 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV063 UT WOS:A1996UV06300046 ER PT J AU Ptuskin, VS Jones, FC Ormes, JF AF Ptuskin, VS Jones, FC Ormes, JF TI On using the weighted slab approximation in studying the problem of cosmic-ray transport SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; diffusion; methods, analytical ID HELIOSPHERE; GALAXY; ENERGY AB The weighted slab approximation has been used for many years as an approximation to the solution of the full equation for the interstellar propagation of cosmic-ray nuclei. The method has the advantage that the full propagation equation is separated into two independent equations, one for the nuclear physics, the slab model, and one for the astrophysics, the path length distribution or weights. This method is exact (at least for particles with the same charge to mass ratio) in the extreme relativistic regime where energy loss can be neglected but is known to be inaccurate when energy loss is not negligible. In this paper we describe an approach to extending the utility of this technique into regimes where energy change cannot be neglected. Using this method we can show that for the ''leaky box'' model or models employing diffusion with no convection the weighted slab approximation can give exact solutions only if the escape time or diffusive mean free path is a separable function of position and energy per nucleon (or rigidity). C1 NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RP Ptuskin, VS (reprint author), UNIV MARYLAND, INST PHYS SCI & TECHNOL, COLLEGE PK, MD 20742 USA. NR 17 TC 13 Z9 13 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 JUL 10 PY 1996 VL 465 IS 2 BP 972 EP 981 DI 10.1086/177482 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV063 UT WOS:A1996UV06300047 ER PT J AU Kallman, TR Kahn, S AF Kallman, TR Kahn, S TI Photoionization equilibrium modeling of iron L line emission SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic processes; line, formation; X-rays, stars ID X-RAY-SPECTRUM; FE-XVII; PLASMAS; RATES AB We present models for the emission spectra of photoionized gases in the intermediate energy (0.5-10 keV) X-ray region, including a detailed and up-to-date treatment of the atomic physics associated with the iron L shell. We discuss the general properties of iron L shell emission-line strengths and recombination continuum emission-and compare the strengths of these features with iron K shell emission and with the spectral features produced by other elements in the same energy range. C1 LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. RP Kallman, TR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,WASHINGTON,DC, USA. NR 23 TC 83 Z9 85 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1996 VL 465 IS 2 BP 994 EP & DI 10.1086/177485 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV063 UT WOS:A1996UV06300050 ER PT J AU ONeill, PE Chauhan, NS Jackson, TJ AF ONeill, PE Chauhan, NS Jackson, TJ TI Use of active and passive microwave remote sensing for soil moisture estimation through corn SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID VEGETATION CANOPIES; EMISSION; SURFACE; BACKSCATTERING; MODEL; LAYER AB Over the past several years NASA, USDA, and Princeton University have collaborated to conduct hydrology field experiments in instrumented research watersheds in Pennsylvania and Oklahoma with a goal of characterizing the spatial and temporal variability of soil moisture using microwave sensors. As part of these experiments, L-band radar data from both truck and aircraft sensors were used to validate the performance of a vegetation scattering model in which discrete scatter random media techniques were employed to calculate vegetation transmissivity and scattering. These parameters were then used in a soil moisture prediction algorithm based on a radiative transfer approach utilizing aircraft passive microwave data from the L-band PBMR and ESTAR radiometers. Soil moisture was predicted in both experiments for several large corn fields which represented the densest vegetation canopies of all the test fields. Over the 20 per cent change in soil moisture encountered in the experiments, the match of predicted to measured soil moisture was excellent, with an average absolute error of about 0.02 cm(3) cm(-3). C1 GEORGE WASHINGTON UNIV,DEPT ELECT ENGN & COMP SCI,WASHINGTON,DC 20052. ARS,USDA,HYDROL LAB,BARC W,BELTSVILLE,MD 20705. RP ONeill, PE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH 974,LAB HYDROSPHER PROC,GREENBELT,MD 20771, USA. RI O'Neill, Peggy/D-2904-2013 NR 29 TC 45 Z9 47 U1 1 U2 7 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 10 PY 1996 VL 17 IS 10 BP 1851 EP 1865 PG 15 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA UR078 UT WOS:A1996UR07800004 ER PT J AU Quirk, JJ Karni, S AF Quirk, JJ Karni, S TI On the dynamics of a shock-bubble interaction SO JOURNAL OF FLUID MECHANICS LA English DT Article ID ADAPTIVE MESH REFINEMENT; FAST GAS INTERFACE; NON-UNIFORM MEDIA; WAVES; PROPAGATION; REFLECTION; ALGORITHM; MODEL; LAWS AB We present a detailed numerical study of the interaction of a weak shock wave with an isolated cylindrical gas inhomogeneity. Such interactions have been studied experimentally in an attempt to elucidate the mechanisms whereby shock waves propagating through random media enhance mixing. Our study concentrates on the early phases of the interaction process which are dominated by repeated refractions and reflections of acoustic fronts at the bubble interface. Specifically, we have reproduced two of the experiments performed by Haas & Sturtevant: a Mach 1.22 planar shock wave, moving through air, impinges on a cylindrical bubble which contains either helium or Refrigerant 22. These flows are modelled using the two-dimensional compressible Euler equations for a two-component fluid (air-helium or air-Refrigerant 22). Utilizing a novel shock-capturing scheme in conjunction with a sophisticated mesh refinement algorithm, we have been able to reproduce numerically the intricate mechanisms that were observed experimentally, e.g. transition from regular to irregular refraction, cusp formation and shock wave focusing, multi-shock and Mach shock structures, and jet formation. The level of agreement lends credibility to a number of observations that can be made using information from the simulations for which there is no experimental counterpart. Thus we can now present an updated description for the dynamics of a shock-bubble interaction which goes beyond that provided by the original experiments. C1 NASA, LANGLEY RES CTR, INST COMP APPLICAT SCI & ENGN, HAMPTON, VA 23681 USA. NYU, COURANT INST MATH SCI, NEW YORK, NY 10012 USA. NR 47 TC 174 Z9 188 U1 1 U2 26 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 JUL 10 PY 1996 VL 318 BP 129 EP 163 DI 10.1017/S0022112096007069 PG 35 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA UZ075 UT WOS:A1996UZ07500007 ER PT J AU Beall, AC AF Beall, AC TI Carrier crew correct SO AVIATION WEEK & SPACE TECHNOLOGY LA English DT Letter RP Beall, AC (reprint author), NASA,AIRCRAFT OPERAT DIV,SHUTTLE CARRIER AIRCRAFT PROJECT PILOT,HOUSTON,TX 77058, 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 SN 0005-2175 J9 AVIAT WEEK SPACE TEC JI Aviat. Week Space Technol. PD JUL 8 PY 1996 VL 145 IS 2 BP 6 EP 6 PG 1 WC Engineering, Aerospace SC Engineering GA UV945 UT WOS:A1996UV94500005 ER PT J AU Huang, ZC Chen, JC Mott, DC Shu, PK AF Huang, ZC Chen, JC Mott, DC Shu, PK TI High performance GaN linear array SO ELECTRONICS LETTERS LA English DT Article DE gallium nitride; metal-semiconductor-metal structures ID ULTRAVIOLET AB A 1 x 16 GaN linear array is reported using a metal-semiconductor-metal structure. The array showed a very high responsivity of 3250 A/W at 360 nm under an applied bias of 10 V, and a response time of 0.5+/-0.2 ms. The responsivity has more than three orders of magnitude difference between the UV region and the visible region. The array also shows a very good uniformity. C1 UNIV MARYLAND,DEPT COMP SCI & ELECT ENGN,CATONSVILLE,MD 21228. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Huang, ZC (reprint author), HUGHES STX CORP,7701 GREENBELT RD,SUITE 400,GREENBELT,MD 21770, USA. NR 6 TC 9 Z9 10 U1 0 U2 1 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD JUL 4 PY 1996 VL 32 IS 14 BP 1324 EP 1325 DI 10.1049/el:19960868 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA UZ510 UT WOS:A1996UZ51000056 ER PT J AU Phillips, DH Quelch, GE AF Phillips, DH Quelch, GE TI Normal-valent ClO(n)X compounds for n=2, 3 and X=Cl,H: An MCSCF investigation SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID LYING ELECTRONIC STATES; FLUORINE PEROXIDE FOOF; TEMPERATURE-DEPENDENCE; VIBRATIONAL FREQUENCIES; MOLECULAR-STRUCTURE; FORCE-CONSTANTS; BRANCHING RATIO; F2 MOLECULE; ABINITIO; THERMOCHEMISTRY AB A series of normal-valent compounds of potential interest with respect to atmospheric chlorine chemistry have been investigated using MCSCF ab initio methods with a good basis set. Comparisons of total energies of the compounds of interest with those of the radical precursors for complete active space wave functions including the bonding and antibonding orbitals of the molecules and the open shell orbitals of the radicals indicate that HOOCl, HOOOCl, and ClOOOCl are stable. Similar results for the compounds HOOH, ClOOCl, and HOOOH, which have been the subject of experimental or previous, more comprehensive, theoretical investigations, are presented for comparison. The predictions of stability for HOOCl and HOOOCl are of particular interest. HOOCl, which is the logical intermediate in the forward and backward reactions between HO + ClO and HOO + Cl, may be stabilized under some atmospheric and laboratory conditions. The role of HOOCl as an intermediate and the fact that the HOOCl adduct might be stabilized in certain parts of the stratosphere were suggested previously by Weissman et al. Also, Stimpfle et al. discussed HOOOCl as a possible intermediate in the HOO + ClO reaction but concluded on the basis of Benson's group additivity rules that its dissociation energy was probably too small for the molecule to be stable. The present results indicate that HOOOCl is sufficiently stable to be formed under some stratospheric conditions. At the MCSCF level of theory, HOOCl is predicted to have an electronic binding energy intermediate between those of ClOOCl and HOOH, while HOOOCl and ClOOOCl are predicted to have binding energies similar to that of ClOOCl. C1 WAKE FOREST UNIV,DEPT CHEM,WINSTON SALEM,NC 27109. RP Phillips, DH (reprint author), NASA,LANGLEY RES CTR,NESB,DIV MAT,MAIL STOP 231,HAMPTON,VA 23681, USA. NR 57 TC 15 Z9 15 U1 0 U2 5 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUL 4 PY 1996 VL 100 IS 27 BP 11270 EP 11275 DI 10.1021/jp9532780 PG 6 WC Chemistry, Physical SC Chemistry GA UV312 UT WOS:A1996UV31200012 ER PT J AU Bosela, PA Ludwiczak, DR AF Bosela, PA Ludwiczak, DR TI A new pre-loaded membrane geometric stiffness matrix with full rigid body capabilities SO COMPUTERS & STRUCTURES LA English DT Article ID SPACE AB Space structures, due to economic considerations, must be light-weight. Accurate prediction of the natural frequencies and mode shapes is critical for determining the structural adequacy of components, and designing a control system. The total stiffness of a member, in many cases, includes both the elastic stiffness of the material as well as additional geometric stiffness due to pre-load (initial stress stiffness). The pre-load causes serious reservations on the use of standard finite element techniques of solution. In particular, a phenomenon known as ''grounding'', or false stiffening, of the stiffness matrix occurs during rigid body rotation. The author has previously shown that that the grounding of a beam element is caused by a lack of rigid body rotational capability, and is typical of beam geometric stiffness matrices formulated by others, including those with higher-order effects. Having identified the source of the problem as the force imbalance inherent in the formulations, the author developed a beam stiffness matrix from a directed force perspective, and showed that the resultant global stiffness matrix contained complete rigid body mode capability, and performed well in the diagonalization methodology customarily used in dynamic analysis. In this paper, the authors investigate the ''grounding'' of membrane elements, and develop a new membrane element with rigid body rotational capabilities. Copyright (C) 1996 Elsevier Science Ltd C1 NASA,LEWIS RES CTR,DYNAM BRANCH,STRUCT SYST DIV,ENGN DIRECTORATE,CLEVELAND,OH 44135. RP Bosela, PA (reprint author), CLEVELAND STATE UNIV,DEPT ENGN TECHNOL,CLEVELAND,OH 44115, USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD JUL 3 PY 1996 VL 60 IS 1 BP 159 EP 168 DI 10.1016/0045-7949(95)60341-7 PG 10 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA UM707 UT WOS:A1996UM70700017 ER PT J AU Ernst, WG Paylor, ED AF Ernst, WG Paylor, ED TI Study of the reed dolomite aided by remotely sensed imagery, Central White-Inyo Range, easternmost California SO AAPG BULLETIN-AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS LA English DT Article ID WIND RIVER BASIN; REFLECTANCE SPECTROSCOPY; SPECTRAL REFLECTANCE; MINERALS; AREAS AB Remote sensing methods are of great value in assessing the stratigraphy and geologic structure of inaccessible terrains, especially where lithologic contrasts are marked. In this paper, we show that such techniques can be successfully applied to a massive carbonate unit, the Reed Dolomite, exposed in the Waucoba Mountain, Blanco Mountain, and Mount Barcroft quadrangles of east-central California. Airborne NS-001, satellite Landsat TM, and SPOT panchromatic imagery combined with conventional geologic mapping were employed to demonstrate that observed spectral variations on false-color images were caused by subtle compositional variations of the dolomite. Based on reflectance differences and field investigations, six discrete bedding units were recognized in exposures of the Reed Dolomite. From lower to upper, they are (1) very coarse grained, granular, gray pisolitic, blocky dolomite; (2) medium-grained, white, oolitic, massive dolomite; (3) fine- to coarse-grained, light-gray, oolitic, massive crystalline dolomite and rare interbedded rusty quartzarenite; (4) medium-file-grained, cross-stratified, locally ocherous brown, interlayered quartzarenite, tan siltstone, and sandy dolomite; (5) fine-grained, thin-bedded, sparsely oolitic, buff dolomite; and (6) fine-grained, fissile, dull white dolomite. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Ernst, WG (reprint author), STANFORD UNIV,SCH EARTH SCI,DEPT GEOG & ENVIRONM SCI,STANFORD,CA 94305, USA. NR 25 TC 4 Z9 4 U1 0 U2 1 PU AMER ASSN PETROL GEOLOGISTS PI TULSA PA 1444 S BOULDER AVE PO BOX 979, TULSA, OK 74101 SN 0149-1423 J9 AAPG BULL JI AAPG Bull.-Am. Assoc. Petr. Geol. PD JUL PY 1996 VL 80 IS 7 BP 1008 EP 1026 PG 19 WC Geosciences, Multidisciplinary SC Geology GA UV926 UT WOS:A1996UV92600004 ER PT J AU Cook, R AF Cook, R TI Mars Pathfinder mission operations concept SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 2nd IAA International Conference on Low-Cost Planetary Missions CY APR 16-19, 1996 CL JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD SP Int Acad Astronaut, Ctr Natl Etud Spatiales, Deut Agenur Raumfahrtangelegenheiten, European Space Agcy, Inst Space & Astronaut Sci, NASA, Planetary Soc, Space Res Inst HO JOHNS HOPKINS UNIV, APPL PHYS LAB AB Mars Pathfinder is one of the first of NASA's Discovery series of low cost planetary missions. A number of innovative design, fabrication, and management techniques have been adopted during the development phase to stay within the $150M (FY'92) cost cap. With the upcoming December 1996 launch, the same faster, better, cheaper spirit is being applied to develop a low cost approach for mission operations. The operability of the Flight System and Ground Data System enable an operations architecture in which all primary activities are performed by a core group of functional generalists. This group consists of experienced development and test personnel whose skills are augmented with cross-training and contingency testing. The small size of this team combined with a flat management structure permit highly streamlined and efficient operations processes. This efficiency is critical during the surface mission when daily updates to the operational plan will occur. Copyright (C) 1997 Published by Elsevier Science Ltd. RP Cook, R (reprint author), CALTECH,JET PROP LAB,MARS PATHFINDER PROJECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 1 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-AUG PY 1996 VL 39 IS 1-4 BP 71 EP 80 DI 10.1016/S0094-5765(96)00124-5 PG 10 WC Engineering, Aerospace SC Engineering GA WG267 UT WOS:A1996WG26700010 ER PT J AU Noreen, G Kinman, P Bokulic, R AF Noreen, G Kinman, P Bokulic, R TI Detection of very weak transmissions from deep space SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 2nd IAA International Conference on Low-Cost Planetary Missions CY APR 16-19, 1996 CL JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD SP Int Acad Astronaut, Ctr Natl Etud Spatiales, Deut Agenur Raumfahrtangelegenheiten, European Space Agcy, Inst Space & Astronaut Sci, NASA, Planetary Soc, Space Res Inst HO JOHNS HOPKINS UNIV, APPL PHYS LAB AB Designers of future planetary missions often reduce spacecraft transmitter power and oscillator stability requirements to decrease mission cost. Unfortunately, these reductions can make it impossible to detect weak signals from deep space using conventional demodulation techniques. The new Block V receiver being installed in the Deep Space Network (DSN) can recover suppressed carrier signals and can utilize very narrow loop bandwidths - as narrow as 0.1 Hz. However, operations at very narrow tracking loop bandwidths are quite sensitive to spacecraft oscillator stability. Low-cost oscillators planned for future missions can force the use of wide tracking loop bandwidths, leading to reduced carrier tracking performance. This reduced carrier tracking performance can, in turn, lead to a significant increase in required spacecraft transmitter power. This paper presents the theory behind coherent detection of very weak telemetry from deep space. It then briefly recounts tests characterizing Block V performance for the NEAR spacecraft in two-way coherent operations and presents recommendations for mission designers. Copyright (C) 1997 Elsevier Science Ltd. RP Noreen, G (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91125, USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-AUG PY 1996 VL 39 IS 1-4 BP 81 EP 90 DI 10.1016/S0094-5765(96)00125-7 PG 10 WC Engineering, Aerospace SC Engineering GA WG267 UT WOS:A1996WG26700011 ER PT J AU Spear, AJ Golombek, MP AF Spear, AJ Golombek, MP TI Mars Pathfinder project progress report SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 2nd IAA International Conference on Low-Cost Planetary Missions CY APR 16-19, 1996 CL JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD SP Int Acad Astronaut, Ctr Natl Etud Spatiales, Deut Agenur Raumfahrtangelegenheiten, European Space Agcy, Inst Space & Astronaut Sci, NASA, Planetary Soc, Space Res Inst HO JOHNS HOPKINS UNIV, APPL PHYS LAB AB Mars Pathfinder, designed and built at the Jet Propulsion Laboratory/California Institute of Technology under contract to NASA's Office of Space Science, is the second of NASA's ''cheaper, better, faster'' Discovery missions; the first, the Near Earth Asteroid Rendezvous mission, was launched February 17, 1996 to tag up with Eros in February 1999. Launching on December 2, 1996 and landing on Mars on July 4, 1997, Pathfinder will demonstrate a low-cost delivery system to the surface of Mars. Historically, spacecraft that orbit or land on a distant body carry a massive amount of fuel for braking at the planet. Pathfinder requires fuel only to navigate to Mars; the spacecraft aerobrakes into the Mars atmosphere directly from Earth-Mars transfer trajectory, deploys a parachute at 10 km above the surface and, within 100 m of the surface, fires solid rockets for final braking prior to deployment of airbags that cushion touchdown. After landing, petals open to upright the lander, followed by deployment of a small rover and several science instruments. A major objective of Pathfinder-acquisition and return of engineering data on entry, descent, and landing (EDL) and lander performance-will be completed within the first few hours after landing. In addition, the lander will transmit images of the Martian surface the first day. Next, a rover will be deployed, as early as the first day, to perform mobility tests, image its surroundings, including the lander, and place an alpha proton x-ray spectrometer (APXS) against a rock or soil to make elemental composition measurements. The primary mission durations for the rover and lander are one week and one month, respectively. However, there is nothing to preclude longer operations up to a year. Pathfinder will also accomplish a focused, exciting set of science investigations with a stereo, multicolor lander imager on a pop-up mast; atmospheric instrumentation for measuring a pressure, temperature and density profile during entry and descent and for monitoring martian weather after landing; and the rover with its forward and aft cameras and the APXS. The APXS and the visible to near infrared filters on the lander imaging system will determine the elemental composition and constrain the mineralogy of rocks and other surface materials, which can be used to address first order questions concerning the composition of the crust, its differentiation and the development of weathering products. Regular tracking of the lander will allow determination of the martian pole of rotation, its precession since Viking era measurements, and the moment of inertia, which should allow discrimination between interior models that include a metallic core and those that do not. The Pathfinder Landing Site selected is Ares Vallis (19.5 degrees N, 32.8 degrees W), which is near the sub-solar latitude (15 degrees N) for maximum solar power at landing on July 4, 1997 and is at 2 km below the datum for correct operation of the parachute. The site is in Chryse Planitia a lowland where a number of catastrophic floods from the highlands to the north debouch. It is a ''grab bag'' site with the potential for sampling a wide variety of different martian crustal materials, such as ancient crustal materials, intermediate age ridged plains and a variety of reworked channel materials. Even though the exact provenance of the samples would not be known, data from subsequent orbital remote sensing missions could be used to infer the provenance for the ''ground truth'' samples studied by Pathfinder. Available data suggest the site is about as rocky as the Viking sites, but perhaps a bit less dusty. This site has streamlined islands nearby, carved by the flood, and a very smooth depositional surface at Viking resolution, except for small hills and secondary craters. This paper reports on the status of Mars Pathfinder's drive to space qualify its Flight System for launch on December 2, 1996 under a cost cap-in particular how the Project is dealing with qualification of its entry, descent and landing event and the surface operations phase as well as the normal launch and space flight phases. It also reports on its landing site selection and science plan. Copyright (C) 1997 Elsevier Science Ltd. RP Spear, AJ (reprint author), CALTECH,JET PROP LAB,MARS PATHFINDER PROJECT,4800 OAK GROVE DR,M-S 230-235,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 1 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-AUG PY 1996 VL 39 IS 1-4 BP 91 EP 99 DI 10.1016/S0094-5765(96)00126-9 PG 9 WC Engineering, Aerospace SC Engineering GA WG267 UT WOS:A1996WG26700012 ER PT J AU Shirley, DL AF Shirley, DL TI ''Mars on $300k a day'': The Mars international conference on low-cost planetary missions SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 2nd IAA International Conference on Low-Cost Planetary Missions CY APR 16-19, 1996 CL JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD SP Int Acad Astronaut, Ctr Natl Etud Spatiales, Deut Agenur Raumfahrtangelegenheiten, European Space Agcy, Inst Space & Astronaut Sci, NASA, Planetary Soc, Space Res Inst HO JOHNS HOPKINS UNIV, APPL PHYS LAB AB The Mars Exploration Program is pioneering a series of ''better, faster, cheaper'' missions to Mars over at least the next 10 years, and possibly well into the 21st century. The overall cost of the program is somewhat over $100M per year including launch vehicles and operations, for two launches every 26 months. (This works out to about $300K per day.) A programmatic strategy has been developed involving selection of a science theme for the program, a long-term industrial partnership for spacecraft development, continuous infusion of new technology, and integration of the individual projects into an overall program so that synergy between projects can be maximized. A number of process improvements have been made in procurement, concurrent engineering, rapid prototyping, and integrated payload selection, among others. Copyright (C) 1997 Elsevier Science Ltd. RP Shirley, DL (reprint author), CALTECH,JET PROP LAB,MARS EXPLORAT PROGRAM,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-AUG PY 1996 VL 39 IS 1-4 BP 101 EP 110 DI 10.1016/S0094-5765(96)00127-0 PG 10 WC Engineering, Aerospace SC Engineering GA WG267 UT WOS:A1996WG26700013 ER PT J AU Casani, EK AF Casani, EK TI Reduced cost and increased capability through technology in the new millennium SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 2nd IAA International Conference on Low-Cost Planetary Missions CY APR 16-19, 1996 CL JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD SP Int Acad Astronaut, Ctr Natl Etud Spatiales, Deut Agenur Raumfahrtangelegenheiten, European Space Agcy, Inst Space & Astronaut Sci, NASA, Planetary Soc, Space Res Inst HO JOHNS HOPKINS UNIV, APPL PHYS LAB AB The National Aeronautics and Space Administration's (NASA's) New Millennium Program (NMP) is designed to reduce the cost of spacecraft in the 21st century while simultaneously increasing spacecraft capabilities, thereby increasing the return on our investment in space exploration. The NMP process is being enacted in the following manner: We are developing a science vision for the 21st century and identifying the attendant missions of this vision. These missions, in turn, will specify the capabilities that future spacecraft require. Technology-validation flights will be selected to demonstrate specific high pay-off technologies needed to provide these capabilities. These hey technologies are categorized by certain areas - autonomy, microelectronics, communications, and so on and will be flight validated prior to the 21st century in order to enable our vision for the next century. To that end, and keeping in mind our science vision, the technologies will primarily be those that allow us to reduce the size of spacecraft instruments, and in turn the size of the spacecraft itself, so that smaller launch vehicles can be employed Also, these technologies will provide for autonomous spacecraft capability and shorter mission flight times so that the ground operations staff for future space missions can be reduced, thus bringing down costs in this area as well. This paper presents specific examples of these hey technologies and their pay-offs. Copyright (C) 1997 Elsevier Science Ltd. RP Casani, EK (reprint author), CALTECH,JET PROP LAB,NEW MILLENNIUM PROGRAM,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-AUG PY 1996 VL 39 IS 1-4 BP 153 EP 160 DI 10.1016/S0094-5765(96)00132-4 PG 8 WC Engineering, Aerospace SC Engineering GA WG267 UT WOS:A1996WG26700018 ER PT J AU Price, HW Carraway, JB Matousek, SE Staehle, RL Terrile, RJ Wyatt, EJ AF Price, HW Carraway, JB Matousek, SE Staehle, RL Terrile, RJ Wyatt, EJ TI Pluto express sciencecraft system design SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 2nd IAA International Conference on Low-Cost Planetary Missions CY APR 16-19, 1996 CL JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD SP Int Acad Astronaut, Ctr Natl Etud Spatiales, Deut Agenur Raumfahrtangelegenheiten, European Space Agcy, Inst Space & Astronaut Sci, NASA, Planetary Soc, Space Res Inst HO JOHNS HOPKINS UNIV, APPL PHYS LAB AB A number of mission system architectures have been studied for a Pluto flyby mission, with the goal of achieving the most cost effective means of meeting a well defined set of science and technology objectives. The current Pluto Express approach at JPL incorporates emerging new technologies to reduce cost, mass, power, and volume, without sacrificing performance, science, or operations capability. The design has evolved through a number of option studies involving an extensive trade space which includes alternate power sources and various propulsion and trajectory options. The results of this trade study have been coupled with a new development implementation approach to create a highly integrated concurrently engineered mission system called a ''sciencecraft.'' The current approach results in a Sciencecraft Module with dry mass of less than 100 kg, power consumption of less than 100 watts, and functional simplicity to achieve high reliability, operability, and a low total mission cost. Copyright (C) 1997 Elsevier Science Ltd. RP Price, HW (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-AUG PY 1996 VL 39 IS 1-4 BP 207 EP 215 DI 10.1016/S0094-5765(96)00138-5 PG 9 WC Engineering, Aerospace SC Engineering GA WG267 UT WOS:A1996WG26700024 ER PT J AU Rapp, D Naderi, F Neugebauer, M Sevilla, D Sweetnam, D Burnett, D Wiens, R Smith, N Clark, B McComas, D Stansbery, E AF Rapp, D Naderi, F Neugebauer, M Sevilla, D Sweetnam, D Burnett, D Wiens, R Smith, N Clark, B McComas, D Stansbery, E TI The Suess-Urey mission (return of solar matter to Earth) SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 2nd IAA International Conference on Low-Cost Planetary Missions CY APR 16-19, 1996 CL JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD SP Int Acad Astronaut, Ctr Natl Etud Spatiales, Deut Agenur Raumfahrtangelegenheiten, European Space Agcy, Inst Space & Astronaut Sci, NASA, Planetary Soc, Space Res Inst HO JOHNS HOPKINS UNIV, APPL PHYS LAB AB The Suess-Urey (S-U) mission has been proposed as a NASA Discovery mission to return samples of matter from the Sun to the Earth for isotopic and chemical analyses in terrestrial laboratories to provide a major improvement in our knowledge of the average chemical and isotopic composition of the solar system. The S-U spacecraft and sample return capsule will be placed in a halo orbit around the L1 Sun-Earth libration point for two years to collect solar wind ions which implant into large passive collectors made of ultra-pure materials. Constant Spacecraft-Sun-Earth geometries enable simple spin stabilized attitude control, simple passive thermal control, and a fixed medium gain antenna. Low data requirements and the safety of a Sun-pointed spinner, result in extremely low mission operations costs. Copyright (C) 1997 Elsevier Science Ltd. RP Rapp, D (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91125, USA. NR 0 TC 3 Z9 3 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-AUG PY 1996 VL 39 IS 1-4 BP 229 EP 238 DI 10.1016/S0094-5765(96)00140-3 PG 10 WC Engineering, Aerospace SC Engineering GA WG267 UT WOS:A1996WG26700026 PM 11540763 ER PT J AU Gavit, SA Powell, G AF Gavit, SA Powell, G TI The New Millennium Program's Mars Microprobe Mission SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 2nd IAA International Conference on Low-Cost Planetary Missions CY APR 16-19, 1996 CL JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD SP Int Acad Astronaut, Ctr Natl Etud Spatiales, Deut Agenur Raumfahrtangelegenheiten, European Space Agcy, Inst Space & Astronaut Sci, NASA, Planetary Soc, Space Res Inst HO JOHNS HOPKINS UNIV, APPL PHYS LAB AB The second deep-space advanced technology validation mission in NASA's New Millennium Program will demonstrate planetary micropenetrator technologies. Two microprobes, each consisting of a very low-mass aeroshell and penetrator system, are planned to launch in January 1999 and arrive at Mars in December, 1999. The 2 kg probes ballistically enter the martian atmosphere and passively orient themselves to meet peak heating and impact requirements. Upon impacting the martian surface, the probes will punch through the entry aeroshell and separate into a fore and aftbody system. The forebody will reach a depth of 0.5 to 2 meters, while the aftbody will remain on the surface for communications. Each penetrator system includes a suite of highly miniaturized components needed for future micropenetrator networks: primary batteries, power electronics, control and data handling microelectronics, telecommunications equipment, an antenna, and a science payload package. This paper will summarize key features of the microprobe mission and system design, as well as discuss the technologies proposed for flight. Copyright (C) 1997 Elsevier Science Ltd. RP Gavit, SA (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 2 TC 5 Z9 5 U1 2 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL-AUG PY 1996 VL 39 IS 1-4 BP 273 EP 280 DI 10.1016/S0094-5765(96)00145-2 PG 8 WC Engineering, Aerospace SC Engineering GA WG267 UT WOS:A1996WG26700031 ER PT J AU Garg, A Noebe, RD Darolia, R AF Garg, A Noebe, RD Darolia, R TI Crystallography of the NiHfSi phase in a NiAl (0.5Hf) single-crystal alloy SO ACTA MATERIALIA LA English DT Article AB Small additions of Hf to conventionally processed NiAl single crystals result in the precipitation of a high density of cuboidal G-phase along with a newly identified silicide phase. Both of these phases form in the presence of Si which is not an intentional alloying addition but is a contaminant resulting from contact with the ceramic shell molds during directional solidification of the single-crystal ingots. The morphology, crystal structure and orientation relationship (O.R.) of the silicide phase in a NiAl(0.5 at.%Hf) single-crystal alloy have been determined using transmission electron microscopy, electron microdiffraction and energy dispersive X-ray spectroscopy. Qualitative elemental analysis and indexing of the electron microdiffraction patterns From the new phase indicate that it is an orthorhombic NiHfSi phase with unit cell parameters, a = 0.639 nm, b = 0.389 nm and c = 0.72 nm, and space group Pnma. The NiHfSi phase forms as thin rectangular plates on {111}(NiAl) planes with an O.R. that is given by (100)(NiHfSi) parallel to (111)(NiAl) and [010](NiHfSi) parallel to [(1) over bar 01](NiAl). Twelve variants of the NiHfSi phase were observed in the alloy and the number of variants and rectangular morphology of NiHfSi plates are consistent with symmetry requirements. Quenching experiments indicate that nucleation of the NiHfSi phase in NiAl(Hf) alloys is aided by the formation of [111](NiAl) vacancy loops that form on the {111}(NiAl) planes. Copyright (C) 1996 Metallurgica Inc. C1 GE CO,AIRCRAFT ENGINES,CINCINNATI,OH 45215. RP Garg, A (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 10 TC 15 Z9 15 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 1359-6454 J9 ACTA MATER JI Acta Mater. PD JUL PY 1996 VL 44 IS 7 BP 2809 EP 2820 DI 10.1016/1359-6454(95)00374-6 PG 12 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA UU562 UT WOS:A1996UU56200020 ER PT J AU Bennett, GL AF Bennett, GL TI Reaching the outer planets - With or without the UN SO AEROSPACE AMERICA LA English DT Editorial Material C1 NASA,ADV SPACE PROP SYST,WASHINGTON,DC 20546. NR 0 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 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1996 VL 34 IS 7 BP 26 EP & PG 6 WC Engineering, Aerospace SC Engineering GA UX381 UT WOS:A1996UX38100010 ER PT J AU Rosenzweig, C Tubiello, FN AF Rosenzweig, C Tubiello, FN TI Effects of changes in minimum and maximum temperature on wheat yields in the central US - A simulation study SO AGRICULTURAL AND FOREST METEOROLOGY LA English DT Article ID CLIMATE CHANGE; CROP RESPONSE; MODEL; CERES AB Recent observations and general circulation models indicate that future temperature changes linked to global warming might be characterized by a marked asymmetry between daytime maxima and nighttime minima. We investigate the importance of such a pattern in determining future wheat (Triticum aestivum) yields in the Central United States by using a dynamic crop growth model, CERES-Wheat, modified to include physiological effects of temperature and CO2 on canopy photosynthesis. Simulations are run at four sites spanning a north-south transect of the Central US; four mean temperatures increases (1-4 degrees C) are applied to baseline daily climate data (1951-1980). The effects of two different scenarios of temperature change (minimum and maximum temperatures equally raised; minima increased three times as much as maxima in agreement with recent observations) are analyzed under both current (330 ppm) and elevated (550 ppm) CO2 concentrations. The main mechanisms controlling the simulated wheat responses are direct and indirect temperature effects on wheat phenological development. Negative effects of temperature on simulated wheat yields are reduced when minima increase more than maxima. Yield changes are consistently negative under temperature change and current CO2 concentration, while they range from positive to negative under temperature change and elevated CO2 concentration. Responses vary across the transect, with larger negative effects occurring at the southernmost site. C1 NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. COLUMBIA UNIV, CTR CLIMATE SYST RES, NEW YORK, NY 10025 USA. NR 32 TC 43 Z9 52 U1 2 U2 12 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1923 J9 AGR FOREST METEOROL JI Agric. For. Meteorol. PD JUL PY 1996 VL 80 IS 2-4 BP 215 EP 230 DI 10.1016/0168-1923(95)02299-6 PG 16 WC Agronomy; Forestry; Meteorology & Atmospheric Sciences SC Agriculture; Forestry; Meteorology & Atmospheric Sciences GA UV522 UT WOS:A1996UV52200009 ER PT J AU Pritchard, JI Adelman, HM SobieszczanskiSobieski, J AF Pritchard, JI Adelman, HM SobieszczanskiSobieski, J TI Optimization for minimum sensitivity to uncertain parameters SO AIAA JOURNAL LA English DT Article ID OPTIMAL-DESIGN AB A procedure to design a structure for minimum sensitivity to uncertainties in problem parameters is described. The approach is to directly minimize the sensitivity derivatives of the optimum design with respect to fixed design parameters using a nested optimization procedure, The procedure is demonstrated for the design of a bimetallic beam for minimum weight with insensitivity to uncertainties in structural properties, The beam is modeled with finite elements based on two-dimensional beam analysis, A sequential quadratic programming procedure used as the optimizer supplies the Lagrange multipliers that are used to calculate the optimum sensitivity derivatives. The procedure is validated by comparing the optimization results to parametric studies. C1 NASA,LANGLEY RES CTR,STRUCT DYNAM BRANCH,HAMPTON,VA 23681. NASA,LANGLEY RES CTR,STRUCT DIV,HAMPTON,VA 23681. RP Pritchard, JI (reprint author), NASA,LANGLEY RES CTR,VEHICLE STRUCT DIRECTORATE,ARMY RES LAB,HAMPTON,VA 23681, USA. NR 16 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1996 VL 34 IS 7 BP 1501 EP 1504 DI 10.2514/3.13259 PG 4 WC Engineering, Aerospace SC Engineering GA UV574 UT WOS:A1996UV57400025 ER PT J AU Goodman, ML AF Goodman, ML TI A three-dimensional, iterative mapping procedure for the implementation of an ionosphere-magnetosphere anisotropic Ohm's law boundary condition in global magnetohydrodynamic simulations - Reply SO ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES LA English DT Letter RP Goodman, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0992-7689 J9 ANN GEOPHYS JI Ann. Geophys.-Atmos. Hydrospheres Space Sci. PD JUL PY 1996 VL 14 IS 7 BP 775 EP 775 PG 1 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA UY680 UT WOS:A1996UY68000012 ER PT J AU Beecken, BP Fossum, ER AF Beecken, BP Fossum, ER TI Determination of the conversion gain and the accuracy of its measurement for detector elements and arrays SO APPLIED OPTICS LA English DT Article DE conversion gain; photon noise limit; detector-array uniformity; charge coupled device; active pixel sensor AB Standard statistical theory is used to calculate how the accuracy of a conversion-gain measurement depends on the number of samples. During the development of a theoretical basis for this calculation, a model is developed that predicts how the noise levels from different elements of an ideal detector array are distributed. The model can also be used to determine what dependence the accuracy of measured noise has on the size of the sample. These features have been confirmed by experiment, thus enhancing the credibility of the method for calculating the uncertainty of a measured conversion gain. (C) 1996 Optical Society of America C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Beecken, BP (reprint author), BETHEL COLL,DEPT PHYS,ST PAUL,MN 55112, USA. NR 8 TC 17 Z9 17 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 1 PY 1996 VL 35 IS 19 BP 3471 EP 3477 DI 10.1364/AO.35.003471 PG 7 WC Optics SC Optics GA UW460 UT WOS:A1996UW46000022 PM 21102737 ER PT J AU Singh, KP Drake, SA White, NE Simon, T AF Singh, KP Drake, SA White, NE Simon, T TI ROSAT observations of five chromospherically active stars SO ASTRONOMICAL JOURNAL LA English DT Article ID RS-CANUM-VENATICORUM; MAIN-SEQUENCE STARS; CORONAL TEMPERATURES; ANGULAR DIAMETERS; HOT COMPANIONS; BINARY; EVOLUTION; EMISSION; GIANTS; SOLAR AB We present x-ray spectra of three chromospherically active binaries, HR 7428, FF Aqr, and IX Per, and two active giant stars, 29 Dra and HR 9024. The spectra were obtained using the Position Sensitive Proportional Counter (PSPC) on the ROSAT satellite. For coronal plasma models with 1-temperature or a-temperature components, we find that a range of heavy element abundances, from solar to extreme sub-solar abundances similar to those that have been inferred from analyses of ASCA spectra, provide acceptable fits to the observed PSPC spectra. The highest signal-to-noise spectrum of 29 Dra requires either a 1- or 2-temperature model with greatly sub-solar (photospheric) abundances or else a 3-component model with solar abundances. The degeneracy of these results, i.e., the fact that quite different models can produce acceptable fits to the PSPC spectra, means that it is difficult to infer the temperature structure of a corona from a PSPC spectra analysis without a priori knowledge of the prevailing coronal abundances, and vice versa. We also show that uncertainties in the intervening interstellar column densities can affect the inferred temperatures and/or abundances. Notwithstanding these difficulties, our analysis confirms that models having similar subsolar abundances to those inferred from ASCA and EUVE spectra of active coronal stars do indeed produce good fits to PSPC spectra. This general consistency between different instruments implies that explanations for the subsolar abundances that invoke systematic biases due to instrumental effects can now be ruled out. (C) 1996 American Astronomical Society. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. NASA,GODDARD SPACE FLIGHT CTR,USRA,GREENBELT,MD 20771. RP Singh, KP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 6602,GREENBELT,MD 20771, USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 49 TC 15 Z9 15 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1996 VL 112 IS 1 BP 221 EP 229 DI 10.1086/118003 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UU510 UT WOS:A1996UU51000020 ER PT J AU Cohen, M Witteborn, FC Bregman, JD Wooden, DH Salama, A Metcalfe, L AF Cohen, M Witteborn, FC Bregman, JD Wooden, DH Salama, A Metcalfe, L TI Spectral irradiance calibration in the infrared .6. 3-35 mu m spectra of three southern standard stars SO ASTRONOMICAL JOURNAL LA English DT Article ID ALPHA-CENTAURI-A; ANGULAR DIAMETERS; PHOTOMETRY; SPECTROPHOTOMETRY; APPROXIMATIONS; SPECTROSCOPY; TEMPERATURE; EVOLUTION; GIANTS; CO AB We present three new absolutely calibrated continuous stellar spectra from 3 to 35 mu m, constructed as far as possible from actual observed spectral fragments taken from the Kuiper Airborne Observatory (KAO), and the IRAS Low Resolution Spectrometer (LRS). These stars-alpha(1) Cen, alpha TrA, and epsilon Car-augment our previous archive of complete absolutely calibrated spectra for northern K and M giants. All these spectra have a common calibration pedigree. The wavelength coverage is ideal for calibration of many existing and proposed ground-based, airborne, and satellite sensors. KAO and IRAS data in the 15-30 mu m range suggest that the spectra of cool giants are close to Rayleigh-Jeans slopes. Our observations of alpha(1) Cen, absolutely calibrated via our adopted Sirius model, indicate an angular diameter in very good agreement with values in the literature, demonstrating ''closure'' of the set of spectra within our absolute framework. We compare our observed alpha(1) Cen spectrum with a published grid of theoretical models from Kurucz, and adopt a plausible theoretical shape, that fits our spectrum, as a secondary reference spectrum in the southern sky. (C) 1996 American Astronomical Society. C1 UNIV CALIF BERKELEY,RADIO ASTRON LAB,BERKELEY,CA 94720. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. ESA,DIV ASTROPHYS,ISO SCI OPERAT CTR,VILLAFRANCA,SPAIN. RP Cohen, M (reprint author), JAMIESON SCI & ENGN INC,SUITE 204,5321 SCOTTS VALLEY DR,SCOTTS VALLEY,CA 95066, USA. NR 37 TC 28 Z9 28 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1996 VL 112 IS 1 BP 241 EP 251 DI 10.1086/118006 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UU510 UT WOS:A1996UU51000023 ER PT J AU Evans, NR Holberg, JB Polidan, RS AF Evans, NR Holberg, JB Polidan, RS TI Voyager observations of the companion of the classical cepheid S muscae SO ASTRONOMICAL JOURNAL LA English DT Article ID FAR-ULTRAVIOLET SPECTROPHOTOMETRY; STARS; MASS AB We have observed the companion of the Cepheid S Mus with the Voyager ultraviolet spectrometer, including a spectrum of the background. We have derived the energy distribution from 912 to 3200 Angstrom using the reddening obtained from Cepheid colors corrected for the effect of the companion. This has been compared with three Morgan-Keenan ''dagger'' spectral standards of appropriate spectral types. The addition of the Voyager flux to the energy distribution provides a clear discriminant between B3 and B5, and shows that S Mus B is a good match to both of the B3 V spectral standards. Although there is some uncertainty in the H-2 absorption correction, even the S Mus B spectrum uncorrected for H-2 absorption has more flux at 1000 Angstrom than the B5 star. (C) 1996 American Astronomical Society. C1 SMITHSONIAN ASTROPHYS OBSERV,CAMBRIDGE,MA 02138. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. NASA,GODDARD SPACE FLIGHT CTR,LAB ASTRON & SPACE PHYS,GREENBELT,MD 20771. RP Evans, NR (reprint author), YORK UNIV,DEPT PHYS & ASTRON,4700 KEELE ST,N YORK,ON M3J 1P3,CANADA. NR 24 TC 4 Z9 4 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1996 VL 112 IS 1 BP 264 EP 268 DI 10.1086/118009 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UU510 UT WOS:A1996UU51000026 ER PT J AU Fekel, FC AF Fekel, FC TI Chromospherically active stars .15. HD 8357=AR Piscium, an extremely active RS CVn system SO ASTRONOMICAL JOURNAL LA English DT Article ID CA-II-H; BINARY STARS; CANUM-VENATICORUM; ROTATIONAL VELOCITIES; IRAS OBSERVATIONS; EMISSION; CATALOG; VARIABILITY; PHOTOMETRY; HD-8357 AB One of the first x-ray sources optically identified as a chromospherically active star, HD 8357=AR Piscium, is a double-lined binary consisting of a K1 IV primary and G7 V secondary. Careful examination of the Ca II H and K lines indicates that only the primary is active, having strong Ca II H and K, H epsilon, and Ha emission. The system has an orbital period of 14.3023 days and an eccentricity of 0.185. Such an eccentricity is not particularly unusual for chromospherically active stars with periods between 10 and 20 days. An assumed mass of 0.92 M. for the secondary results in a 1.12 M. for the subgiant primary and an orbital inclination of 30 degrees. Projected rotational velocities for the primary and secondary are 6.5+/-2 and 3.5+/-2 km s(-1), respectively. Lithium abundances for the two stars are significantly different with log epsilon(Li)=2.0 for the primary and less than or equal to 1.35 for the secondary. While the abundance of the subgiant is consistent with standard theory, comparison with a survey of other field subgiants suggests that it may be lithium rich. Individual theoretical evolutionary tracks and cluster ages suggest an age of 7-8 Gyr. HD 8357 is a star of the intermediate-disk population having a distance of 39 pc or a parallax of 0.026 ''. (C) 1996 American Astronomical Society. C1 TENNESSEE STATE UNIV,CTR EXCELLENCE INFORMAT SYST,NASHVILLE,TN 37203. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES 82,HUNTSVILLE,AL 35812. RP Fekel, FC (reprint author), TENNESSEE STATE UNIV,CTR AUTOMATED SPACE SCI,330 10TH AVE N,NASHVILLE,TN 37203, USA. NR 66 TC 15 Z9 15 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1996 VL 112 IS 1 BP 269 EP 275 DI 10.1086/118010 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UU510 UT WOS:A1996UU51000027 ER PT J AU Lee, U Strohmayer, TE AF Lee, U Strohmayer, TE TI Nonradial oscillations of rotating neutron stars: The effects of the Coriolis force SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars; neutron; rotation; oscillations ID LOW-FREQUENCY OSCILLATIONS; G-MODE OSCILLATIONS; DIFFERENTIAL ROTATION AB We discuss the effects of rotation (spin) on a variety of the oscillation modes of a neutron star model which has both solid and fluid regions in the interior. Within the framework of Newtonian dynamics, we derive oscillation equations for wave propagation in the solid crust and fluid regions of the rotating neutron star. We include the Coriolis force and neglect both the centrifugal force and the rotational deformation of the star. Applying a perturbation technique to the oscillation equations, we calculate the first order rotational corrections to the eigenfnquency and eigenfunction for a variety of the oscillation modes. Using a different computational method, we generally confirm the previous results of Strohmayer (1991) for the first order rotational corrections. Because of the effects of rotation the spheroidal modes associated with 1 acquire toroidal components (associated with l' = l +/- 1) of the displacement at the first order in Omega. Similarly the toroidal modes associated with I in the solid crust acquire spheroidal components (associated with l' = l +/- 1) of the displacement, which generates the temperature and density variations associated with the oscillations. We solve the differential equations describing the oscillations in order to investigate some other aspects of the rotational effects which are not sufficiently described by the perturbation method. For example, we consider avoided crossings between several different oscillation modes. We show that avoided crossings between the f mode, p modes, shear s modes, and toroidal t modes are likely to occur since the f and low radial order p mode frequencies are interspersed with those of the high radial order s and t modes of the neutron star. We also calculate the r modes propagating in the surface fluid region above the solid crust. Although the r-mode oscillation periods observed in an inertial frame are essentially determined by the rotation period of the star, we show that the r mode associated with m = -1 and l = 1 is an exception to this rule. C1 ECOLE NORMALE SUPER LYON, PHYS LAB, F-69364 LYON 07, FRANCE. UNIV SPACE RES ASSOC, HIGH ENERGY ASTROPHYS LAB, NASA, GSFC, GREENBELT, MD 20771 USA. NR 36 TC 23 Z9 23 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 JUL PY 1996 VL 311 IS 1 BP 155 EP 171 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV894 UT WOS:A1996UV89400017 ER PT J AU Colombi, S Bouchet, FR Hernquist, L AF Colombi, S Bouchet, FR Hernquist, L TI Self-similarity and scaling behavior of scale-free gravitational clustering SO ASTROPHYSICAL JOURNAL LA English DT Article DE large-scale structure of universe; methods, numerical; methods, statistical ID INVARIANT MATTER DISTRIBUTION; N-BODY SIMULATIONS; GALAXY DISTRIBUTION; EXPANDING UNIVERSE; CORRELATION HIERARCHY; STATISTICAL-ANALYSIS; REDSHIFT SURVEY; FLUCTUATIONS; GRAVITY; CATALOG AB We determine the scaling properties of the probability distribution of the smoothed density field in N-body simulations of expanding universes with scale-free initial power-spectra, {\delta(k)\(2)] proportional to k(n), with particular attention to the predictions of the stable clustering hypothesis. We concentrate our analysis on the ratios S-Q(l) = xi(Q)/xi(2)(Q-1), where xi(Q) is the average Q-body correlation function over a cell of a radius l. According to the stable clustering hypothesis, S-Q should not depend on scale. We performed measurements for Q less than or equal to 5. The behavior of the higher order correlations is studied through that of the void probability distribution, P-0(l), which is the probability of finding an empty cell of radius l. If the stable clustering hypothesis applies, the function P-0 should also exhibit remarkable scaling properties. In our analysis, we take carefully into account various misleading effects, such as initial grid contamination, loss of dynamics due to the short-range softening of the forces, and finite volume size of our simulations. Only after correcting for the latter do we find agreement of the measured S-Q with the expected self-similar behavior. Otherwise, P-0 is only weakly sensitive to such effects and closely follows the expected self-similar behavior. The ratios exhibit two plateaus separated by a smooth transition when xi(2)(l) similar to 1. In the weakly nonlinear regime xi(2) less than or similar to 1, the results are in reasonable agreement with the predictions of perturbation theory. In the strongly nonlinear regime, xi(2) > 1, the S-Q values are larger than in the weakly nonlinear regime, and increasingly so with -n. They are well fitted by the expression S-Q = (xi(2)/100)(0.04(Q-2))S-Q for all n and 3 less than or equal to Q less than or equal to 5. This weak dependence on scale proves a small but significant departure from the stable clustering predictions, at least for n = 0 and n = +1. The analysis P-0 confirms that the expected scale invariance of the functions S-Q is not exactly attained in the part of the nonlinear regime we probe, except possibly for n = -2 and marginally for n = -1. In these two cases, our measurements are not accurate enough to be discriminant. On the other hand, we could demonstrate that the observed power-law behavior of S-Q cannot be generalized as such to arbitrary order in Q. Indeed, we show that this would induce scaling properties of P-0 that are incompatible with those measured. C1 INST ASTROPHYS,CNRS,F-75014 PARIS,FRANCE. UNIV CALIF SANTA BARBARA,INST THEORET PHYS,SANTA BARBARA,CA 93106. UNIV CALIF SANTA CRUZ,BOARD STUDIES ASTRON & ASTROPHYS,SANTA CRUZ,CA 95064. RP Colombi, S (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,POB 500,BATAVIA,IL 60510, USA. RI Bouchet, Francois/B-5202-2014 NR 57 TC 78 Z9 80 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1996 VL 465 IS 1 BP 14 EP 33 DI 10.1086/177398 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UR889 UT WOS:A1996UR88900003 ER PT J AU Soria, R Mould, JR Watson, AM Gallagher, JS Ballester, GE Burrows, CJ Casertano, S Clarke, JT Crisp, D Griffiths, RE Hester, JJ Hoessel, JG Holtzman, JA Scowen, PA Stapelfeldt, KR Trauger, JT Westphal, JA AF Soria, R Mould, JR Watson, AM Gallagher, JS Ballester, GE Burrows, CJ Casertano, S Clarke, JT Crisp, D Griffiths, RE Hester, JJ Hoessel, JG Holtzman, JA Scowen, PA Stapelfeldt, KR Trauger, JT Westphal, JA TI Detection of the tip of the red giant branch in NGC 5128 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, distances and redshifts; galaxies, individual (NGC 5128); galaxies, stellar content; stars, Hertzsprung-Russell diagram ID DWARF ELLIPTICAL GALAXIES; STELLAR POPULATIONS; GLOBULAR-CLUSTERS; CENTAURUS-A; DISTANCE; PHOTOMETRY; NGC-5128 AB We present a color-magnitude diagram of more than 10,000 stars in the halo of the galaxy NGC 5128 (Centaurus A), based on WFPC2 images through V-band and I-band filters. The position of the red giant branch (RGB) stars is compared with the loci of the red giant branch in six well-studied globular clusters and in the dwarf elliptical galaxy NGC 185; the tip of the RGB is signalled by an observed turn-up in the luminosity function at I similar or equal to 24.1 +/- 0.1 mag; this yields a distance modulus (m - M)(0) = 27.8 +/- 0.2 for NGC 5128 (i.e., a distance of 3.6 +/- 0.2 Mpc), in agreement with previous determinations based on the planetary nebulae luminosity function and on the surface brightness fluctuations technique. The presence of an intermediate-age stellar population (similar to 5 Gyr) is suggested by the luminosity function of the asymptotic giant branch stars, extending up to I = 22.6 mag (for V-I > 2) and M(bol) similar to -5 mag; however, the number of these stars constrains the intermediate-age stellar population in the halo of NGC 5128 to be less than similar to 10% of the total. The color distribution at constant I magnitude, albeit affected by the completeness level of our sample, strongly suggests a mean value of [Fe/H] > -0.9 dex, possibly similar to the value found in M31 and higher than that observed in NGC 185. Like the M31 halo, the halo of NGC 5128 exhibits a broad range of levels of chemical enrichment. C1 UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. JOHNS HOPKINS UNIV,DEPT ASTRON,BALTIMORE,MD 21218. CALTECH,JET PROP LAB,PASADENA,CA 91109. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. LOWELL OBSERV,FLAGSTAFF,AZ 86001. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP Soria, R (reprint author), AUSTRALIAN NATL UNIV,INST ADV STUDIES,MT STROMLO & SIDING SPRING OBSERV,PRIVATE BAG,CANBERRA,ACT 2601,AUSTRALIA. RI Stapelfeldt, Karl/D-2721-2012; Clarke, John/C-8644-2013 NR 50 TC 95 Z9 96 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1996 VL 465 IS 1 BP 79 EP 90 DI 10.1086/177403 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UR889 UT WOS:A1996UR88900008 ER PT J AU Pravdo, SH Shaklan, SB AF Pravdo, SH Shaklan, SB TI Astrometric detection of extrasolar planets: Results of a feasibility study with the Palomar 5 meter telescope SO ASTROPHYSICAL JOURNAL LA English DT Article DE astrometry; atmospheric effects; methods, data analysis open clusters and associations, individual (NGC 2420); planetary systems ID T-TAURI STARS; ATMOSPHERIC LIMITATIONS; UNSEEN COMPANIONS; PSR 1257+12; CCD; PROGRAM; SYSTEM AB The detection of extrasolar planets around stars like the Sun remains an important goal of astronomy. We present results from Palomar 5 m observations of the open cluster NGC 2420 in which we measure some of the sources of noise that will be present in an astrometric search for extrasolar planets. This is the first time that such a large aperture has been used for high-precision astrometry. We find that the atmospheric noise is 150 mu as hr(1/2) (1 mu as = 1 micro-arcsecond) across a 90 '' field of view and that differential chromatic refraction (DCR) can be calibrated to 128 mu as for observations within 1 hr of the meridian and 45 degrees of zenith. These results confirm that a model for astrometric measurements can be extrapolated to large apertures. We demonstrate, based upon these results. that a large telescope achieves the sensitivity required to perform a statistically significant search for extra solar planets. We describe an astrometric technique to detect planets, the astrometric signals expected, the role of reference stars, and the sources of measurement noise: photometric noise, atmospheric motion between stars, sky background, intrumental noise, and DCR. For the latter, we discuss a method to reduce the noise further to 66 mu as for observations within 1 hr of the meridian and 45 degrees of zenith. We discuss optimal lists of target stars taken from the latest Gliese & Jahreiss catalog of nearby stars with the largest potential astrometric signals, declination limits for both telescope accessibility and reduced DCR, and galactic latitude limits for a sufficiant number of reference stars. Two samples are described from which one can perform statistically significant searches for gas giant planets around nearby stars. One sample contains 100 ''solar class'' stars with an average stellar mass of 0.82 M(.); the other maximizes the number of stars, 574, by searching mainly low-mass M stars. We perform Monte Carlo simulations of the statistical significance of the expected results by using measured and estimated noise quantities. We show the semimajor axis parameter spaces that are searched for each star and how an increase in the length of the observing program expands these spaces. The search over semimajor axis parameter space relates to the theory of gas giant planet formation. RP Pravdo, SH (reprint author), CALTECH,JET PROP LAB,MAIL STOP 306-438,PASADENA,CA 91109, USA. NR 50 TC 45 Z9 45 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1996 VL 465 IS 1 BP 264 EP 277 DI 10.1086/177417 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UR889 UT WOS:A1996UR88900022 ER PT J AU Lanz, T deKoter, A Hubeny, I Heap, SR AF Lanz, T deKoter, A Hubeny, I Heap, SR TI Toward resolving the ''mass discrepancy'' in O-type stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars, atmospheres; stars, early-type; stars, evolution stars, fundamental parameters ID INCLUDING SPHERICAL EXTENSION; MODEL STELLAR ATMOSPHERES; RADIATION-DRIVEN WINDS; HOT STARS; MICROTURBULENCE AB We show that metal line blanketing has an important effect on the atmospheres of hot stars, and we argue that the omission of metal line blanketing in previous non-LTE model atmospheres of O-type stars has led to underestimates of surface gravity and stellar mass. In addition to wind emission, metal line blanketing contributes to the solution of the long-standing discrepancy between spectroscopic and evolutionary masses for O-type stars. To support our argument, we calculated a series of non-LTE stellar atmospheres for O and Of-type stars. We compared the predicted profiles of hydrogen and helium lines produced by (1) a static plane-parallel H-He model, (2) a metal line-blanketed static model, and (3) an extended expanding model atmosphere. We find that simple H-He models produce stronger lines than do our metal line-blanketed models. Consequently, they lead to underestimated gravities. Wind emission is more effective in filling in the wings of H or He lines in the case of large mass-loss rates typical of extreme Of stars. These findings apply equally to young, massive O-type stars and to highly evolved stars, i.e., central stars of planetary nebulae. The lower gravities derived from H-He models yield underestimated masses for young O-type stars, and overestimated masses for highly evolved stars. RP Lanz, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771, USA. NR 22 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1996 VL 465 IS 1 BP 359 EP 362 DI 10.1086/177424 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UR889 UT WOS:A1996UR88900029 ER PT J AU Thompson, DJ Bailes, M Bertsch, DL Esposito, JA Fichtel, CE Harding, AK Hartman, RC Hunter, SD Manchester, RN Mattox, JR vonMontigny, C Mukherjee, R Ramanamurthy, PV Sreekumar, P Fierro, JM Lin, YC Michelson, PF Nolan, PL Kanbach, G MayerHasselwander, HA Merck, M Kniffen, DA Schneid, EJ Kaspi, VM Johnston, S Daugherty, J Ruderman, M AF Thompson, DJ Bailes, M Bertsch, DL Esposito, JA Fichtel, CE Harding, AK Hartman, RC Hunter, SD Manchester, RN Mattox, JR vonMontigny, C Mukherjee, R Ramanamurthy, PV Sreekumar, P Fierro, JM Lin, YC Michelson, PF Nolan, PL Kanbach, G MayerHasselwander, HA Merck, M Kniffen, DA Schneid, EJ Kaspi, VM Johnston, S Daugherty, J Ruderman, M TI Egret observations of high-energy gamma radiation from PSR B1706-44 SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays, observations; pulsars, individual (PSR B1706-44) ID PULSAR PSR1706-44; VELA; CRAB; RAYS AB The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed PSR B1706-44 a number of times between 1991 and 1995. From these data, a more detailed picture of the gamma radiation from this source has been developed, showing several characteristics that distinguish this pulsar from others: the light curve is complex, with evidence of three pulses; there is no detectable unpulsed emission; and the energy spectrum changes slope at 1 GeV. No two of the known gamma-ray pulsars have quite the same characteristics; this diversity makes interpretation in terms of theoretical models difficult. C1 CSIRO, AUSTRALIA TELESCOPE NATL FACIL, EPPING, NSW 2121, AUSTRALIA. STANFORD UNIV, WW HANSEN EXPT PHYS LAB, STANFORD, CA 94305 USA. STANFORD UNIV, DEPT PHYS, STANFORD, CA 94305 USA. MAX PLANCK INST EXTRATERR PHYS, D-85748 GARCHING, GERMANY. HAMPDEN SYDNEY COLL, DEPT PHYS, HAMPDEN SYDNEY, VA 23943 USA. NORTHROP GRUMMAN CORP, BETHPAGE, NY 11714 USA. CALTECH, JET PROP LAB, IPAC, PASADENA, CA 91125 USA. UNIV SYDNEY, RES CTR THEORET ASTROPHYS, SYDNEY, NSW 2006, AUSTRALIA. UNIV N CAROLINA, DEPT COMP SCI, ASHEVILLE, NC 28804 USA. COLUMBIA UNIV, DEPT PHYS, NEW YORK, NY 10027 USA. USRA, COMPTON OBSERV SCI SUPPORT CTR, WASHINGTON, DC USA. RP NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, CODE 661, GREENBELT, MD 20771 USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; Harding, Alice/D-3160-2012 OI Thompson, David/0000-0001-5217-9135; NR 47 TC 62 Z9 63 U1 0 U2 0 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 JUL 1 PY 1996 VL 465 IS 1 BP 385 EP 392 DI 10.1086/177427 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UR889 UT WOS:A1996UR88900032 ER PT J AU Lau, YT Siregar, E AF Lau, YT Siregar, E TI Nonlinear Alfven wave propagation in the solar wind SO ASTROPHYSICAL JOURNAL LA English DT Article DE solar wind; sun, corona; waves ID INTERPLANETARY FLUCTUATIONS; STELLAR WINDS; ACCELERATION; REFLECTION; ATMOSPHERE; TRANSPORT; LINES; MODEL AB We derive a self-consistent set of equations that describe the propagation of nonlinear shear Alfven waves in the solar wind. The equations include the interaction between the waves and wind plasmas and has an exact energy conservation law. Using a truncated Fourier series, we further reduce the system to a simplifed nonlinear model with multiple waves. We solve the model numerically in a radially expanding box with a finite angular size. We find that for linear waves in a time-varying plasma background, the conditions for the WKB approximation are violated in practically the entire radial domain (even at high frequencies), although the scaling of wave amplitudes (delta B) with radial distance and the equipartition between the magnetic and kinetic energy are similar to the WKB results. For nonlinear waves, equipartition still holds, but nonlinear wave reflection enhances the backward propagating waves (in the rest frame of the wind), which leads to a faster drop in delta B than the linear waves. As a result, there is a ''soft'' saturation in which delta B approaches the background magnetic field gradually at large distance. The simplified nonlinear model produces reasonably high wind speed (between 600 and 700 km s(-1)). C1 NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. RP UNIV MARYLAND, INST PLASMA RES, COLLEGE PK, MD 20742 USA. NR 43 TC 24 Z9 24 U1 0 U2 0 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 JUL 1 PY 1996 VL 465 IS 1 BP 451 EP 461 DI 10.1086/177432 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UR889 UT WOS:A1996UR88900037 ER PT J AU Petre, R Becker, CM Winkler, PF AF Petre, R Becker, CM Winkler, PF TI A central stellar remnant in Puppis A SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, individual; pulsars, general; stars, neutron; supernova remnants; X-rays, ISM ID SUPER-NOVA REMNANT; X-RAY; PULSAR; DISCOVERY; VELA AB ROSAT observations of a feature in the center of the Puppis A supernova remnant suggest that it is the stellar remnant of the supernova. This feature has been known since Einstein HRI observations, but convincing evidence that it is unresolved has become available only through observations from the ROSAT HRI. The source has no optical counterpart to limiting magnitude B greater than or similar to 25.0, R greater than or similar to 23.6, nor is there an obvious radio counterpart to a limit of 0.75 mJy at 1.4 GHz. Timing analysis of the X-ray data has indicated neither pulsations nor variability on long time scales. We suggest that this source is the cooling neutron-star remnant of the Puppis A progenitor. The similar to 3700 yr age of the supernova remnant would make this the youngest known neutron star cooling via thermal processes. Assuming it originated at the center of expansion, located 6' to the northeast, requires the stellar remnant to have a transverse velocity similar to 1000 km s(-1). The stellar remnant's velocity is directed roughly opposite to the average proper motion of the fast, oxygen-rich knots, believed to be fragments of the progenitor's outer core, which suggests an anisotropic explosion and recoil of a newly formed:neutron star. C1 MIT, CTR SPACE RES, CAMBRIDGE, MA 02139 USA. MIDDLEBURY COLL, DEPT PHYS, MIDDLEBURY, VT 05753 USA. RP Petre, R (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. NR 35 TC 66 Z9 66 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 JUL 1 PY 1996 VL 465 IS 1 BP L43 EP + DI 10.1086/310141 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UR891 UT WOS:A1996UR89100011 ER PT J AU Scoccimarro, R Frieman, J AF Scoccimarro, R Frieman, J TI Loop corrections in nonlinear cosmological perturbation theory SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE cosmology, theory; methods, analytical; large-scale structure of universe ID LARGE-SCALE STRUCTURE; CORRELATION HIERARCHY; EVOLUTION; APPROXIMATION; UNIVERSE; DENSITY; FLUCTUATIONS; GRAVITY AB Using a diagrammatic approach to Eulerian perturbation theory, we calculate analytically the variance and skewness of the density and velocity divergence induced by gravitational evolution from Gaussian initial conditions, including corrections beyond leading order. Except for the power spectrum, previous calculations in cosmological perturbation theory have been confined to leading order (tree level): we extend these to include loop corrections. For scale-free initial power spectra, P(k) similar to k(n) with -2 less than or equal to n less than or equal to 2, the one-loop variance sigma(2) = [delta(2)] = sigma(l)(2) + 1.82 sigma(l)(4), and the skewness S-3 = [delta(3)]/sigma(4) = 34/7 + 9.8 sigma(l)(2), where sigma(l) is the rms fluctuation of the density field to linear order. (These results depend weakly on the spectral index n, due to the nonlocality of the nonlinear solutions to the equations of motion.) Thus, loop corrections for the (unsmoothed) density held begin to dominate over tree-level contributions (and perturbation theory presumably begins to break down) when sigma(l)(2) similar or equal to 1/2. For the divergence of the velocity field, loop dominance does not occur until sigma(l)(2) approximate to 1. We also compute loop corrections to the variance, skewness, and kurtosis for several nonlinear approximation schemes, where the calculation can be easily generalized to one-point cumulants of higher order and arbitrary number of loops. We find that the Zeldovich approximation gives the best approximation to the loop corrections of exact perturbation theory, followed by the linear potential approximation (LPA) and the frozen flow approximation (FFA), in qualitative agreement with the relative behavior of tree-level results. In LPA and FFA, loop corrections are infrared divergent for spectral indices n less than or equal to -1; this is related to the breaking of Galilean invariance in these schemes. C1 UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP Scoccimarro, R (reprint author), UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637, USA. NR 68 TC 101 Z9 101 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 1996 VL 105 IS 1 BP 37 EP 73 DI 10.1086/192306 PG 37 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV154 UT WOS:A1996UV15400003 ER PT J AU Breininger, DR Larson, VL Oddy, DM Smith, RB Barkaszi, MJ AF Breininger, DR Larson, VL Oddy, DM Smith, RB Barkaszi, MJ TI Florida Scrub-Jay demography in different landscapes SO AUK LA English DT Article ID PREDATION; HAWK AB Florida Scrub-Jay (Aphelocoma coerulescens) demography and cooperative breeding were measured from 1988 to 1993 at two sites (HC and T4) on John F. Kennedy Space Center along Florida's Atlantic coast. The results from HC and T4 sites were compared with published results from the Archbold Biological Station in central Florida. The T4 population increased because of reproductive success and immigration, resulting in a nearly equal nonbreeder sex ratio. Nearly all young Florida Scrub-Jays delayed breeding for at least two years after hatching at T4, similar to Archbold. The HC population decreased because of poor nesting success, and the nonbreeder sex ratio was biased towards males. During the first nesting season after hatching, nearly one of every five HC females bred. Pairs with nonbreeders (potential helpers) usually had greater reproductive success than pairs without nonbreeders at HC and Archbold, but not T4. Pairs with nonbreeders usually had greater survival than pairs without nonbreeders at Archbold, but not at HC or T4. Female breeder mortality was slightly higher than male breeder mortality at T4 and HC, but not at Archbold. Evidence suggested that predation contributed to differences in demographic patterns between study areas. RP Breininger, DR (reprint author), NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899, USA. NR 30 TC 15 Z9 16 U1 2 U2 6 PU AMER ORNITHOLOGISTS UNION PI LAWRENCE PA ORNITHOLOGICAL SOC NORTH AMER PO BOX 1897, LAWRENCE, KS 66044-8897 SN 0004-8038 J9 AUK JI AUK PD JUL PY 1996 VL 113 IS 3 BP 617 EP 625 PG 9 WC Ornithology SC Zoology GA UX242 UT WOS:A1996UX24200011 ER PT J AU Chen, TC Yen, MC Schubert, S AF Chen, TC Yen, MC Schubert, S TI Hydrologic processes associated with cyclone systems over the United States SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID 1979 NORTHERN SUMMER; SCALE ENVIRONMENT; MAINTENANCE; CONVECTION; EQUATIONS; MODELS; JET AB A substantial amount of precipitation in the midlatitudes occurs in association with extratropical cyclones. Using the data generated by version 1 of the Goddard Earth Observing System (GEOS-1) Data Assimilation System for 1985-89, hydrologic processes and the water vapor budget over the United States were analyzed to illustrate the maintenance of precipitable water and precipitation associated with extratropical cyclones. The area-mean divergence of water vapor flux covering the Great Plains and the eastern region of the United States (80 degrees-105 degrees W, 30 degrees-50 degrees N) was adopted as a hydrologic index. The cyclones over this region that have values of this index smaller than minus one standard deviation over a season were selected for analysis. On average, 15 cases were selected for each season. The composite results show a developing baroclinic wave coupled with a low-level cyclone in which the low-level convergent (divergent) center and the upper-level divergent (convergent) center ahead of the trough (ridge) are Linked by an upward (downward) branch of the divergent circulation, consistent with the classic cyclone model. Thus, water vapor converges (diverges) through the low-level divergent circulation of the cyclone wave to maintain precipitation (evaporation) centers ahead of the trough (ridge). It is estimated that the amount of water vapor accumulating in the Great Plains and the eastern United States throughout winter (November-March) could be converged by typical cyclones within a month. During summer (May-September), it would take only about half a month for typical cyclones to converge water vapor toward this region sufficient to account for the summer season runoff by streamflow over this region. C1 NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, DATA ASSIMILAT OFF, GREENBELT, MD 20771 USA. RP Chen, TC (reprint author), IOWA STATE UNIV SCI & TECHNOL, DEPT GEOL & ATMOSPHER SCI, ATMOSPHER SCI PROGRAM, 3010 AGRON HALL, AMES, IA 50011 USA. NR 35 TC 6 Z9 6 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD JUL PY 1996 VL 77 IS 7 BP 1557 EP 1567 DI 10.1175/1520-0477(1996)077<1557:HPAWCS>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UZ042 UT WOS:A1996UZ04200008 ER PT J AU Bey, KS Oden, JT AF Bey, KS Oden, JT TI hp-Version discontinuous Galerkin methods for hyperbolic conservation laws SO COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING LA English DT Article ID FINITE-ELEMENT METHOD; POSTERIORI ERROR ESTIMATION; P-VERSION; STRATEGY AB The development of hp-version discontinuous Galerkin methods for hyperbolic conservation laws is presented in this work. A priori error estimates are derived for a model class of linear hyperbolic conservation laws. These estimates are obtained using a new mesh-dependent norm that reflects the dependence of the approximate solution on the local element size and the local order of approximation. The results generalize and extend previous results on mesh-dependent norms to hp-version discontinuous Galerkin methods. A posteriori error estimates which provide bounds on the actual error are also developed in this work. Numerical experiments verify the a priori estimates and demonstrate the effectiveness of the a posteriori estimates in providing reliable estimates of the actual error in the numerical solution. C1 UNIV TEXAS,TEXAS INST COMPUTAT & APPL MATH,AUSTIN,TX 78712. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 20 TC 82 Z9 83 U1 0 U2 1 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0045-7825 J9 COMPUT METHOD APPL M JI Comput. Meth. Appl. Mech. Eng. PD JUL 1 PY 1996 VL 133 IS 3-4 BP 259 EP 286 DI 10.1016/0045-7825(95)00944-2 PG 28 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA UY556 UT WOS:A1996UY55600007 ER PT J AU Callahan, JR AF Callahan, JR TI WET ICE '95 - Fourth IEEE workshop on enabling technologies: Infrastructure for collaborative enterprises SO COMPUTERS IN INDUSTRY LA English DT Editorial Material RP Callahan, JR (reprint author), W VIRGINIA UNIV,NASA,SOFTWARE FACIL 4&5,FAIRMONT,WV 26554, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0166-3615 J9 COMPUT IND JI Comput. Ind. PD JUL PY 1996 VL 29 IS 1-2 BP 1 EP 3 DI 10.1016/0166-3615(95)00049-6 PG 3 WC Computer Science, Interdisciplinary Applications SC Computer Science GA UW002 UT WOS:A1996UW00200001 ER PT J AU Sheplak, M Spina, EF McGinley, CB AF Sheplak, M Spina, EF McGinley, CB TI Progress in hot-film anemometry for hypersonic flow SO EXPERIMENTAL THERMAL AND FLUID SCIENCE LA English DT Article DE hot-film anemometry; photolithography; hypersonic flow AB A robust microsensor hot-film probe has been developed to obtain continuous turbulence measurements in moderately severe hypersonic environments. This probe represents a significant advancement of an existing concept. Optimization for hypersonic flow is achieved through sensor placement, the use of high-temperature materials, and state-of-the-art microphotolithographic fabrication techniques. Tests in Mach 6 air and Mach 11 helium flows have been very promising. The probe has exhibited excellent characteristics, including a frequency response that is a factor of 5 higher than that of previous hot-film sensors. The qualitative spectra of the anemometer fluctuations has been smooth and repeatable. Despite these improvements, heat conduction into the substrate still complicates the probe response. A review of the physics of this problem is presented along with a plan for the characterization of the response via several dynamic calibration techniques. C1 SYRACUSE UNIV,CTR HYPERSON,SYRACUSE,NY 13244. NASA,LANGLEY RES CTR,HAMPTON,VA 23692. NR 37 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0894-1777 J9 EXP THERM FLUID SCI JI Exp. Therm. Fluid Sci. PD JUL PY 1996 VL 13 IS 1 BP 21 EP 28 DI 10.1016/0894-1777(96)00001-5 PG 8 WC Thermodynamics; Engineering, Mechanical; Physics, Fluids & Plasmas SC Thermodynamics; Engineering; Physics GA UT671 UT WOS:A1996UT67100003 ER PT J AU Orsi, JA Jaenicke, HW AF Orsi, JA Jaenicke, HW TI Marine distribution and origin of prerecruit chinook salmon, Oncorhynchus tshawytscha, in southeastern Alaska SO FISHERY BULLETIN LA English DT Article ID OREGON AB Chinook salmon, Oncorhynchus tshawytscha, <71 cm total length, are typically not retained in directed marine fisheries of southeastern Alaska because of size restrictions; consequently, little is known of the origin or temporal and spatial distribution of these prerecruits. To obtain such data, commercial power trollers were chartered to fish for small chinook salmon with small hooks and lures within the Alexander Archipelago (inside waters) and the adjacent, coastal region (outside waters). During the 135-d study in February, May, and September 1986-87, a total of 5,838 prerecruit chinook salmon were caught, of which 539 contained coded-wire tags with information on stock origin. Age -.O chinook. salmon were caught in September during their first year at sea; they originated predominately from stream-type stocks of southeastern Alaska. Age -.1 chinook salmon in February and May were primarily from stream-type stocks of southeastern Alaska; however, by September most were from ocean-type stocks from British Columbia, Washington, and Oregon streams. Most age -.2 chinook salmon were from ocean-type stocks of southern origin. Average net marine migration rates of different chinook salmon age groups ranged from 0.1 to 6.9 km/d; the highest rates were for age 1.0 fish from Washington and Oregon. For coded-wire-tagged chinook salmon of the same ocean age group, growth rates of ocean-type fish were significantly (P<0.05) higher than growth rates of stream-type fish during most periods. Spatial distribution also differed by race: stream-type fish predominated in inside waters and ocean-type fish in outside waters. This study identifies the importance of marine waters of southeastern Alaska as a nursery area for an amalgam of prerecruit chinook salmon stocks originating between Oregon and southeastern Alaska, a range of 1,800 km. RP Orsi, JA (reprint author), NOAA,NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,AUKE BAY LAB,11305 GLACIER HIGHWAY,JUNEAU,AK 99801, USA. NR 41 TC 15 Z9 17 U1 0 U2 5 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1996 VL 94 IS 3 BP 482 EP 497 PG 16 WC Fisheries SC Fisheries GA UU710 UT WOS:A1996UU71000008 ER PT J AU Quinn, TP Nielsen, JL Gan, C Unwin, MJ Wilmot, R Guthrie, C Utter, FM AF Quinn, TP Nielsen, JL Gan, C Unwin, MJ Wilmot, R Guthrie, C Utter, FM TI Origin and genetic structure of chinook salmon, Oncorhynchus tshawytscha, transplanted from California to New Zealand: Allozyme and mtDNA evidence SO FISHERY BULLETIN LA English DT Article ID RAINBOW-TROUT; ATLANTIC SALMON; POPULATIONS; PATTERNS; PACIFIC; MANAGEMENT; MIGRATION; EVOLUTION; DISTANCE; STOCKS AB Chinook salmon, Oncorhynchus tshawytscha, transplanted from the Sacramento River, California, to the Waitaki River catchment of New Zealand at the turn of the century rapidly colonized many South Island rivers. Allozyme genotype and mtDNA haplotype frequencies were obtained from tissue samples from chinook salmon in Waitaki, Rakaia, Waimakariri, and Clutha rivers in New Zealand and compared with data from populations in the Sacramento River to provide further information on the origin of the NZ populations and to ascertain the genetic changes that have taken place since the transplant. Neither allozyme nor mtDNA unequivocally identified an ancestral ''seasonal'' run (fall, winter, or spring) for the NZ chinook salmon. Sacramento River samples collectively diverged from the NZ samples at allozyme loci, and mtDNA indicated greater similarity between NZ samples and fall-run rather than winter and spring runs from the Sacramento River. Significant variation was detected by mtDNA analysis between only two of the four populations within NZ, one of which has been landlocked by an impassable dam since 1956. The allozyme data identified significant variation within NZ, although less than has been documented among Sacramento River populations. The NZ populations also showed less genetic diversity (mean number of alleles per locus, proportion of loci that were polymorphic, and mean heterozygosity) than the Sacramento River populations. These lower values are consistent with a population bottleneck in the first generations after transplantation into the Waitaki River catchment and with founder effects during the formation of populations in the other NZ rivers. The combination of genetic differences and phenotypic variation among the NZ populations indicates that Pacific salmon populations can develop rapidly after colonizing suitable habitat. C1 US FOREST SERV,USDA,PACIFIC SW RES STN,ALBANY,CA 94710. STANFORD UNIV,HOPKINS MARINE STN,PACIFIC GROVE,CA 93950. NATL INST WATER & ATMOSPHERE,CHRISTCHURCH,NEW ZEALAND. NATL MARINE FISHERIES SERV,AUKE BAY LAB,JUNEAU,AK 99801. RP Quinn, TP (reprint author), UNIV WASHINGTON,SCH FISHERIES,POB 357980,SEATTLE,WA 98195, USA. NR 60 TC 49 Z9 49 U1 1 U2 7 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1996 VL 94 IS 3 BP 506 EP 521 PG 16 WC Fisheries SC Fisheries GA UU710 UT WOS:A1996UU71000010 ER PT J AU VanDoornik, DM Milner, GB Winans, GA AF VanDoornik, DM Milner, GB Winans, GA TI Transferrin polymorphism in coho salmon, Oncorhynchus kisutch, and application to genetic stock identification SO FISHERY BULLETIN LA English DT Article ID PACIFIC SALMON; BRITISH-COLUMBIA; ALLELE FREQUENCY; TEMPORAL CHANGES; POPULATIONS; CALIFORNIA AB The blood protein transferrin is an important source for identifying genetic variation in coho salmon, Oncorhynchus kisutch, with starch gel electrophoresis. We present new data for transferrin allele frequencies for 48 samples of coho salmon collected at 34 different locations from Oregon to southern British Columbia. To analyze transferrin allele frequencies from a larger geographic area, data from various sources were compiled for 135 samples from sites from California to southern British Columbia. In a statistical analysis of temporal variation within locations, 26 of 65 pairwise comparisons (41%) showed significant differences between samples (P<0.05). An analysis of variance revealed significant between-locale variability and no significant within-locale variability due to whether or not, the brood gears of the samples were three years apart. Relative gene diversity values were 22.3% between geographic regions, 2.1% between stocks within geographic regions, 3.1% between temporal comparisons, and 72.5% for within-sample variation. Total genetic diversity (H-T) was 0.5867 and the average genetic diversity within populations (H-s) equaled 0.425. The samples showed genetic variation that was related to geographic location. Applications of transferrin data to genetic stock identification are discussed in relation to these results. C1 NOAA,NATL MARINE FISHERIES SERV,NW FISHERIES SCI CTR,SEATTLE,WA 98112. RP VanDoornik, DM (reprint author), NOAA,NATL MARINE FISHERIES SERV,NW FISHERIES SCI CTR,MANCHESTER FIELD STN,POB 130,MANCHESTER,WA 98353, USA. NR 31 TC 5 Z9 5 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 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1996 VL 94 IS 3 BP 566 EP 575 PG 10 WC Fisheries SC Fisheries GA UU710 UT WOS:A1996UU71000014 ER PT J AU Joslin, RD AF Joslin, RD TI Simulation of nonlinear instabilities in an attachment-line boundary layer SO FLUID DYNAMICS RESEARCH LA English DT Article ID TRANSITION; STABILITY; FLOW AB The linear and the nonlinear stability of disturbances that propagate along the attachment line of a three-dimensional boundary layer are considered. The spatially evolving disturbances in the boundary layer are computed by direct numerical simulation (DNS) of the unsteady, incompressible Navier-Stokes equations. Disturbances are introduced either by forcing at the inflow or by applying suction and blowing at the wall. Quasi-parallel linear stability theory and a nonparallel theory yield notably different stability characteristics for disturbances near the critical Reynolds number; the DNS results confirm the latter theory. Previously, a weakly nonlinear theory and computations revealed a high wave-number region of subcritical disturbance growth. More recent computations have failed to achieve this subcritical growth. The present computational results indicate the presence of subcritically growing disturbances; the results support the weakly nonlinear theory. Furthermore, an explanation is provided for the previous theoretical and computational discrepancy. In addition, the present results demonstrate that steady suction can be used to stabilize disturbances that otherwise grow subcritically along the attachment line. RP Joslin, RD (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH & ACOUST,MAIL STOP 170,HAMPTON,VA 23681, USA. NR 34 TC 13 Z9 13 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-5983 J9 FLUID DYN RES JI Fluid Dyn. Res. PD JUL PY 1996 VL 18 IS 2 BP 81 EP 97 DI 10.1016/0169-5983(96)00005-6 PG 17 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA UW746 UT WOS:A1996UW74600003 ER PT J AU Browning, LB McSween, HY Zolensky, ME AF Browning, LB McSween, HY Zolensky, ME TI Correlated alteration effects in CM carbonaceous chondrites SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID AQUEOUS ALTERATION; OXYGEN ISOTOPES; OLIVINE GRAINS; METEORITES; MATRIX; PHYLLOSILICATES; INDICATORS; MINERALOGY; ASTEROIDS; HELIUM AB Three parameters are proposed to determine the relative extent of alteration in CM chondrites. The mineralogic alteration index monitors the relative progress of coupled substitutions in the progressive alteration of cronstedtite to Mg-serpentine and increases with increasing alteration. To calculate values of this index, an algorithm has been developed to estimate the average matrix phyllosilicate composition in individual CM chondrites. The second parameter is the volume percent of isolated matrix silicates, which decreases with progressive alteration due to mineral hydration. Finally, the volume percent of chondrule alteration monitors the extent of chondrule phyllosilicate production and increases as alteration proceeds. These parameters define the first CM alteration scale that relies on multiple indicators of progressive alteration. The following relative order of increasing alteration is established by this model: Murchison less than or equal to Bells < Pollen less than or equal to Murray < Mighei < Nogoya < Cold Bokkeveld. The relative degree of aqueous processing Cochabamba and Boriskino experienced is less precisely constrained, although both fall near the middle of this sequence. A comparison between the mineralogic alteration index and literature values for the whole-rock chemistry of CM chondrites reveals several correlations. A positive, nearly linear correlation between bulk H content and progressive CM alteration suggests an approximately constant production rate of new phyllosilicates relative to the mineralogical transition from cronstedtite to Mg-serpentine. The abundance of trapped planetary Ar-36 decreases systematically in progressively altered CM chondrites, suggesting the wholesale destruction of primary noble gas carrier phase(s) by aqueous reactions. Because low temperature fluid-rock reactions are generally associated with large isotopic mass fractionation factors, we also compared our model predictions with delta(18)O values for bulk CM samples. Although some of these data are poorly resolved, the order of increasing delta(18)O values approximates the order of increasing alteration predicted by our model parameters. Multiple correlations between diverse alteration parameters strongly suggest that (a) different CM chondrites experienced similar kinds of processes and conditions, and (b) CM materials experienced in situ alteration on the CM parent body or bodies. C1 UNIV HAWAII MANOA, SCH OCEAN & EARTH SCI & TECHNOL, HAWAII INST GEOPHYS & PLANETOL, HONOLULU, HI 96822 USA. NASA, LYNDON B JOHNSON SPACE CTR, EARTH SCI & SOLAR SYST EXPLORAT DIV, HOUSTON, TX 77058 USA. RP UNIV TENNESSEE, DEPT GEOL SCI, KNOXVILLE, TN 37996 USA. NR 53 TC 169 Z9 169 U1 0 U2 22 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 EI 1872-9533 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD JUL PY 1996 VL 60 IS 14 BP 2621 EP 2633 DI 10.1016/0016-7037(96)00121-4 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UY098 UT WOS:A1996UY09800011 ER PT J AU McCoy, TJ Keil, K Clayton, RN Mayeda, TK Bogard, DD Garrison, DH Huss, GR Hutcheon, ID Wieler, R AF McCoy, TJ Keil, K Clayton, RN Mayeda, TK Bogard, DD Garrison, DH Huss, GR Hutcheon, ID Wieler, R TI A petrologic, chemical, and isotopic study of Monument Draw and comparison with other acapulcoites: Evidence for formation by incipient partial melting SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Review ID RAY EXPOSURE AGES; ORDINARY CHONDRITES; NOBLE-GASES; DIFFERENTIATED ASTEROIDS; MEGAREGOLITH INSULATION; AR-40-AR-39 STANDARDS; COSMOGENIC NUCLIDES; PHOSPHATE GRAINS; IRON METEORITE; TRAPPED XENON AB We have conducted petrologic, chemical, and isotopic studies of acapulcoites (Acapulco, Monument Draw, Yamato 74063, ALH A77081, ALH A81261, ALH A81315, ALH 78230, ALH A81187 and ALH 84190) in an attempt to constrain their genesis. Acapulcoites have distinctly different oxygen isotopic compositions than silicate inclusions in IAB and IIICD irons, winonaites and ureilites and, thus, formed on a different parent body. Oxygen isotopic compositions, which are slightly heterogeneous within the group, overlap with lodranites, indicating a likely origin on a common parent body. These groups can be distinguished on the basis of mafic silicate grain size. All acapulcoites have mafic silicate compositions intermediate between E and H chondrites, roughly chondritic mineralogies, achondritic, equigranular textures, micrometer to centimeter sized veins of Fe,Ni-FeS which cross-cut silicate phases, rapid metallographic cooling rates at similar to 600-400 degrees C (10(3)-10(5) degrees C/Myr) and trapped noble gas abundances comparable to type 3-4 ordinary chondrites. They exhibit variable mafic silicate zoning, abundance of Fe,Ni-FeS veins, REE abundances and patterns and, possibly, cosmic ray exposure ages (similar to 5-7 Ma). Monument Draw and Yamato 74063 retain rare relict chondrules. Phosphates are associated with Fe,Ni-FeS veins or form separate veins in Monument Draw and Acapulco. Heating and cooling of acapulcoites occurred very early in the history of the Solar System, as evidenced by the Ar-39-Ar-40 ages of similar to 4.51 Ga. These ages appear distinctly younger than the likely formation time for Acapulco of 4.557 Ga, but are older than analogous Ar-39-Ar-40 ages for most chondrites. Acapulcoites formed from a precursor chondrite which differs from known chondrites in mineral and oxygen isotopic compositions. Heating to similar to 950-1000 degrees C resulted in melting at the Fe,Ni-FeS cotectic, but silicates did not melt. Silicate textures resulted from extensive solid-state recrystallization. Heating was by noncollisional sources (e.g., Al-26, electromagnetic induction). Despite uncertainties owing to a lack of data, acapulcoites may have experienced a three-stage thermal history of slow cooling at high temperature, rapid cooling at intermediate temperatures, and slow cooling at low temperatures, possibly resulting from breakup and gravitational reassembly of the parent body. The complex thermal history is also reflected in disequilibrium REE abundances. One or at most two impact events (similar to 7 Ma and possibly similar to 5 Ma ago) are consistent with the cosmic ray exposure ages of all four acapulcoites for which cosmogenic noble gas data exist. C1 NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. UNIV HAWAII MANOA, HAWAII CTR VOLCANOL, HONOLULU, HI 96822 USA. UNIV CHICAGO, ENRICO FERMI INST, CHICAGO, IL 60637 USA. CALTECH, DIV GEOL & PLANETARY SCI, PASADENA, CA 91125 USA. ETH ZURICH, CH-8092 ZURICH, SWITZERLAND. RP UNIV HAWAII MANOA, SCH OCEAN & EARTH SCI & TECHNOL, HAWAII INST GEOPHYS & PLANETOL, HONOLULU, HI 96822 USA. RI Wieler, Rainer/A-1355-2010 OI Wieler, Rainer/0000-0001-5666-7494 NR 108 TC 98 Z9 99 U1 0 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 EI 1872-9533 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD JUL PY 1996 VL 60 IS 14 BP 2681 EP 2708 DI 10.1016/0016-7037(96)00109-3 PG 28 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UY098 UT WOS:A1996UY09800015 ER PT J AU Johnson, DG Orphal, J Toon, GC Chance, KV Traub, WA Jucks, KW Guelachvili, G MorillonChapey, M AF Johnson, DG Orphal, J Toon, GC Chance, KV Traub, WA Jucks, KW Guelachvili, G MorillonChapey, M TI Measurement of chlorine nitrate in the stratosphere using the nu(4) and nu(5) bands SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ABSORPTION; CLONO2; SPECTRA; HNO3; O3 AB We present laboratory measurements of the absorption cross sections of the vg band (540-580 cm(-1)) of chlorine nitrate made under stratospheric conditions of temperature and pressure. We use the measured cross sections and observed mid-infrared stratospheric emission spectra to retrieve mid-latitude vertical mixing ratio profiles for both day and night in the altitude range 20-34 km, and compare the results with a sunset profile obtained simultaneously from solar absorption measurements of the v(4) Q branch at 780 cm(-1). The profiles obtained using these two methods are shown to be in excellent agreement, validating retrievals using the v(4) band. We also find good agreement in this altitude range between the observed day/night ratio and the results of a 1-D photochemical model. C1 UNIV BREMEN,INST ENVIRONM PHYS,D-28334 BREMEN,GERMANY. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV PARIS 06,CNRS UPR 136,LAB PHYS MOL & APPLICAT,CTR ORSAY,F-91405 ORSAY,FRANCE. UNIV PARIS 11,CNRS UPR 136,LAB PHYS MOL & APPLICAT,CTR ORSAY,F-91405 ORSAY,FRANCE. RP Johnson, DG (reprint author), SMITHSONIAN ASTROPHYS OBSERV,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. RI Orphal, Johannes/A-8667-2012; Johnson, David/F-2376-2015 OI Orphal, Johannes/0000-0002-1943-4496; Johnson, David/0000-0003-4399-5653 NR 17 TC 20 Z9 20 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1996 VL 23 IS 14 BP 1745 EP 1748 DI 10.1029/96GL01675 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UV847 UT WOS:A1996UV84700011 ER PT J AU Jaegle, L Yung, YL Toon, GC Sen, B Blavier, JF AF Jaegle, L Yung, YL Toon, GC Sen, B Blavier, JF TI Balloon observations of organic and inorganic chlorine in the stratosphere: The role of HClO4 production on sulfate aerosols SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CLO AB Simultaneous observations of stratospheric organic and inorganic chlorine were made in September 1993 out of Fort Sumner, New Mexico, using the JPL balloon-borne MkIV interferometer. Between 15 and 20 km, a significant fraction (20 - 60%) of the inorganic chlorine could not be accounted for by the sum of measured HCl, ClONO2, and HOCl. Laboratory measurements of the reaction of ClO radicals on sulfuric acid solutions have indicated that, along with HCl, small amounts of perchloric acid, HClO4, were formed. Very little is known about the fate of HClO4 in the stratosphere and we use a photochemical box model to determine the impact of this new species on the partitioning of inorganic chlorine in the stratosphere. Assuming that HClO4 is photochemically stable, it is shown that in the enhanced aerosol loading conditions resulting from Mr. Pinatubo's eruption, HClO4 could represent a significant reservoir of chlorine in the lower stratosphere, sequestering up to 0.2 ppbv (or 50%) of the total inorganic chlorine at 16 km. The occurrence of this new species could bring to closure the inorganic chlorine budget deficiency made apparent by recent ER-2 aircraft ill situ measurements of HCl. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. NR 26 TC 35 Z9 35 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1996 VL 23 IS 14 BP 1749 EP 1752 DI 10.1029/96GL01543 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UV847 UT WOS:A1996UV84700012 PM 11539365 ER PT J AU Gross, RS Hamdan, KH Boggs, DH AF Gross, RS Hamdan, KH Boggs, DH TI Evidence for excitation of polar motion by fortnightly ocean tides SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SEA-LEVEL RESPONSE; BAROMETRIC-PRESSURE; EARTH ROTATION AB The second-degree zonal tide raising potential, which is responsible for tidal changes in the Earth's rotation rate and length-of-day, is symmetric about the polar axis and hence can excite the Earth's polar motion only through its action upon nonaxisymmetric features of the Earth such as the oceans. Ocean tidal excitation of polar motion in the diurnal and semidiurnal tidal bands has been previously detected and examined. Here, the detection of ocean tidal excitation of polar motion in the long period tidal band, specifically at the Mf' (13.63-day) and Mf (13.66-day) tidal frequencies, is reported. Spectra of the SPACE94 polar motion excitation series exhibit peaks at the prograde and retrograde fortnightly tidal periods. After removing effects of atmospheric wind and pressure changes, an empirical model for the effect of the fortnightly ocean tides upon polar motion excitation is obtained by least-squares fitting periodic terms at the Mf and Mf' tidal frequencies to the residual polar motion excitation series. The resulting empirical model is then compared with the predictions of two hydrodynamic ocean tide models. RP Gross, RS (reprint author), CALTECH,JET PROP LAB,MAIL STOP 238-332,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 12 Z9 12 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1996 VL 23 IS 14 BP 1809 EP 1812 DI 10.1029/96GL01596 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UV847 UT WOS:A1996UV84700027 ER PT J AU Konopliv, AS Yoder, CF AF Konopliv, AS Yoder, CF TI Venusian k(2) tidal Love number from Magellan and PVO tracking data SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID GRAVITY; MODEL; POLE AB The k(2) potential Love number which scales the tidal deformation of Venus by the Sun has been estimated from Doppler tracking of Magellan and Pioneer Venus Orbiter (PVO) spacecraft data. The nominal range for k(2) from theoretical models is 0.23 less than or equal to k(2) less than or equal to 0.29 for a liquid iron core and about 0.17 if the iron core has solidified. Our best estimate of this parameter is k(2) = 0.295 +/- 0.066(2x formal sigma) and supports the hypothesis that Venus core is liquid. RP Konopliv, AS (reprint author), CALTECH,JET PROP LAB,MS 301-125J,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 16 TC 29 Z9 29 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1996 VL 23 IS 14 BP 1857 EP 1860 DI 10.1029/96GL01589 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UV847 UT WOS:A1996UV84700039 ER PT J AU Kintner, PM Bonnell, J Arnoldy, R Lynch, K Pollock, C Moore, T Holtet, J Deehr, C StenbaekNielsen, H Smith, R Olson, J Moen, J AF Kintner, PM Bonnell, J Arnoldy, R Lynch, K Pollock, C Moore, T Holtet, J Deehr, C StenbaekNielsen, H Smith, R Olson, J Moen, J TI The SCIFER Experiment SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TRANSVERSELY ACCELERATED IONS; PLASMA-WAVES; IONOSPHERE; REGION; ALTITUDE C1 UNIV NEW HAMPSHIRE,CTR SPACE SCI,DURHAM,NH 03824. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV OSLO,DEPT PHYS,OSLO 3,NORWAY. UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK 99775. UNIV COURSES SVALBARD,N-9170 LONGYEARBYEN,NORWAY. RP Kintner, PM (reprint author), CORNELL UNIV,SCH ELECT ENGN,PHILLIPS HALL,ITHACA,NY 14853, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 19 TC 17 Z9 17 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1996 VL 23 IS 14 BP 1865 EP 1868 DI 10.1029/96GL01260 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UV847 UT WOS:A1996UV84700041 ER PT J AU Arnoldy, RL Lynch, KA Kintner, PM Bonnell, J Moore, TE Pollock, CJ AF Arnoldy, RL Lynch, KA Kintner, PM Bonnell, J Moore, TE Pollock, CJ TI SCIFER - Structure of the cleft ion fountain at 1400 km altitude SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The SCIFER, sounding rocket intersected the cleft ion fountain (CIF) at an altitude of about 1400 km revealing the structure of upward flows and ion acceleration. This altitude range is intermediate, between lower altitude studies using DE-2 and HILAT data and higher altitude studies using DE-1 and EXOS-D data. Within the observed intense ion heating region the ions are consistent with satellite measurements of the cleft ion fountain of DE-1, or the ''ion wall'' of EXOS-D obtained at much higher altitudes. We conclude from the SCIFER data set that the accelerated ion flux levels at 1400 km altitude are similar to the TAI fluxes measured at higher altitudes. Furthermore the transversely accelerated ions are found within separate ''events'' of 30-40 km latitudinal width and have well-defined boundaries. The ion distribution function within an event indicates transverse-beating up to about 40 eV, occurring a few tens of km below the rocket. The SCIFER data set serves to demonstrate that the cleft ion fountain is composed of discrete structures originating poleward of the electron trapping boundary in regions of depleted ionospheric density. C1 CORNELL UNIV,SCH ENGN,ITHACA,NY 14853. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP Arnoldy, RL (reprint author), UNIV NEW HAMPSHIRE,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 11 TC 19 Z9 19 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1996 VL 23 IS 14 BP 1869 EP 1872 DI 10.1029/96GL00475 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UV847 UT WOS:A1996UV84700042 ER PT J AU Kintner, PM Bonnell, J Arnoldy, R Lynch, K Pollock, C Moore, T AF Kintner, PM Bonnell, J Arnoldy, R Lynch, K Pollock, C Moore, T TI SCIFER - Transverse ion acceleration and plasma waves SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AURORAL FIELD LINES; HYDROGEN CYCLOTRON WAVES; LOW-FREQUENCY WAVES; HEAVY-IONS; ENERGIZATION; RESONANCE; CONICS; CLEFT; CUSP AB SCIFER encountered the cleft ion fountain within the cleft ionosphere at 1000 MLT and 1400 km altitude where it was possible to investigate the fine structure of transverse ion acceleration (TIA). Latitudinally narrow (30 km) regions of TIA were found to be closely correlated with broadband low frequency electric fields and reduced ionospheric density. The low frequency electric fields extended up to a few kHz with the largest amplitudes of about 10-20 mV/m(p-p) occurring below 400 Hz. No spectral features ordered by the ion cyclotron frequencies were observed. Outside regions of TIA the ionospheric density was typically 2x10(3) cm(-3) while inside regions of TIA the density dropped to 5x10(2) cm(-3). The correlation between TIA, reduced ionospheric density and broadband low frequency electric fields is so exact, sometimes within a few hundred meters, we interpret the broadband low frequency electric fields as current-driven electrostatic waves, perhaps a mixture of ion cyclotron and ion acoustic waves. C1 UNIV NEW HAMPSHIRE,CTR SPACE SCI,DURHAM,NH 03824. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP Kintner, PM (reprint author), CORNELL UNIV,SCH ELECT ENGN,PHILLIPS HALL,ITHACA,NY 14853, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 31 TC 82 Z9 82 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1996 VL 23 IS 14 BP 1873 EP 1876 DI 10.1029/96GL01863 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UV847 UT WOS:A1996UV84700043 ER PT J AU Moore, TE Pollock, CJ Adrian, ML Kintner, PM Arnoldy, RL Lynch, KA Holtet, JA AF Moore, TE Pollock, CJ Adrian, ML Kintner, PM Arnoldy, RL Lynch, KA Holtet, JA TI The cleft ion plasma environment at low solar activity SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EVENTS; CYCLE AB Low energy (0.3-25 eV) ion plasma composition and three-dimensional differential velocity distribution measurements have been made from the Sounding of the Cleft Ion Fountain Energization Region (SCIFER) mission. SCIFER traveled poleward into the dayside prenoon cleft region under conditions of low solar activity. Upleg measurements show that the subcleft topside had a rapid density fall-off with altitude (n(e) less than or equal to 300 cm(-3) at 1400 km altitude), and that the payload floating potential changed from typical ionospheric negative values of about a volt, to zero or positive values consistent with n(e) less than or equal to 1000 cm(-3) in sunlight. As the payload moved poleward and approached apogee, the ion plasma flux abruptly increased. Observations of Langmuir waves at the electron plasma frequency show the plasma density increased by a factor of 6 over a scale length of similar to 1 km. The plasma density boundary coincided with passage into the cleft region, as judged from the appearance of field-perpendicular ion heating to T-perpendicular to similar to 1 eV, with upward bulk flows of several km/s for H+, and 1-2 km/s for O+, and warm superthermal tails in the core H+ with characteristic energy similar to 4 eV. An inverse association was observed between ion temperature and plasma density, consistent with heating by current-driven waves. The heated cleft plasma was H+-dominated in this region, in stark contrast to the O+ domination observed from 3000-6000 km altitude by DE-1 and Akebono near solar maximum. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. CORNELL UNIV,SCH ELECT ENGN,ITHACA,NY 14853. UNIV NEW HAMPSHIRE,DEPT PHYS,DURHAM,NH 03824. UNIV OSLO,DEPT PHYS,OSLO 3,NORWAY. RP Moore, TE (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,CODE ES83,HUNTSVILLE,AL 35812, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 12 TC 11 Z9 11 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1996 VL 23 IS 14 BP 1877 EP 1880 DI 10.1029/96GL00843 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UV847 UT WOS:A1996UV84700044 ER PT J AU Pollock, CJ Moore, TE Adrian, ML Kintner, PM Arnoldy, RL AF Pollock, CJ Moore, TE Adrian, ML Kintner, PM Arnoldy, RL TI SCIFER - Cleft region thermal electron distribution functions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TEMPERATURE; LATITUDE AB Differential directional ionospheric: electron measurements at energies from <1 to 60 eV have been obtained in the Earth's geomagnetic cleft ionosphere on NBSA's Sounding of the Cleft Region Ion Fountain Energization Region (SCIFER) rocket. We introduce the electron data set, present electron temperature measurements, and show examples of phase space distributions measured near and in the cleft ionosphere. Topside electron temperatures ranged from near 0.15 eV south of the high energy electron trapping boundary to near 1 eV within precipitation regions in the auroral cleft. Field-aligned, electron bursts extend dawn to thermal energies and merge with the core, yielding core heating and anisotropy in the derived electron temperature. One interval is identified where enhanced electron temperature is collocated with a deep density depletion, low frequency electrostatic waves, and transverse ion heating, consistent with operation of the current-driven ion cyclotron instability. On the downleg, in what may be polar cap, the shape of the thermal electron energy distribution was observed to be quite uniform, with temperatures near 0.25 eV. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. CORNELL UNIV,DEPT ELECT ENGN,ITHACA,NY 14853. UNIV NEW HAMPSHIRE,INST STUDY EARTH OCEANS & SPACE,DURHAM,NH 03824. RP Pollock, CJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,CODE ES83,HUNTSVILLE,AL 35812, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 23 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1996 VL 23 IS 14 BP 1881 EP 1884 DI 10.1029/96GL01486 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UV847 UT WOS:A1996UV84700045 ER PT J AU Buevich, YA Webbon, BW AF Buevich, YA Webbon, BW TI Evolution of vapor bubbles in boiling SO HIGH TEMPERATURE LA English DT Article AB A new dynamic theory is proposed of the growth and detachment of vapor bubbles forming on a superheated surface under conditions of nucleate boiling. The equations, describing the increase of the bubble volume and the motion of its center of gravity, are derived for a unified scheme from the law of conservation of mechanical energy of a bubble-liquid system. These equations are free of semiempirical assumptions characteristic of most investigations in the region under treatment. Investigated by way of example is the evolution of a bubble on a horizontal wall, the growth of which is controlled by the rare of vaporization from the bulk of surrounding liquid and from the microlayer separating the bubble from the wall. The new theory is free of the errors of previous studies and helps explain a whole series of effects which, until now, remained unclear. fn particular, it is demonstrated that the force due to the surface tension effects promotes, rather than impedes, bubble detachment. Explanations are provided for the first time for the dependence of the bubble departure size on thermal factors and for the dependence of the rate of its growth on dynamic factors. The conclusions are supported by the results of experiments in nucleate boiling under conditions of reduced gravitation. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Buevich, YA (reprint author), URAL STATE UNIV,EKATERINBURG 620219,RUSSIA. NR 17 TC 1 Z9 1 U1 0 U2 1 PU MAIK NAUKA/INTERPERIODICA PI NEW YORK PA C/O PLENUM/CONSULTANTS BUREAU 233 SPRING ST, NEW YORK, NY 10013 SN 0018-151X J9 HIGH TEMP+ JI High Temp. PD JUL-AUG PY 1996 VL 34 IS 4 BP 568 EP 577 PG 10 WC Physics, Applied SC Physics GA VE186 UT WOS:A1996VE18600013 ER PT J AU Satoh, T Connerney, JEP Baron, RL AF Satoh, T Connerney, JEP Baron, RL TI Emission source model of Jupiter's H-3(+) aurorae: A generalized inverse analysis of images SO ICARUS LA English DT Article ID HUBBLE-SPACE-TELESCOPE; MAGNETIC-FIELD; H-3+ EMISSIONS; JOVIAN AURORA; POLAR AURORA; HOT-SPOTS; UV AURORA; MU-M; ULTRAVIOLET; ATMOSPHERE AB We mapped the distribution of H-3(+) emissions in Jupiter's polar regions utilizing 3.4-mu m images acquired with ProtoCAM at the NASA IRTF. Two data sets, one acquired on February 28 and the other on March 22, 1992, were analyzed independently. A sequence of image mosaics was used to constrain the parameters of an emission source model. The emission source model utilizes an amoral oval traced from the distant magnetosphere, using the O-6 magnetic field model (Connerney, J. E. P. 1992. In Planetary Radio Emissions III (H. O. Rucker, S. J. Bauer, and M. L. Kaiser, Eds.), pp. 13-33, Austrian Academy of Sciences Press, Vienna.) plus the current sheet model (Connerney, J. E. P., M. H. Acuna, and N. F. Ness 1981. J. Geophys. Res. 86, 8370-8384.). Limb positioning errors, photometric uncertainties, atmospheric seeing changes, telescope point spread functions, and disk emissions are all included in the model. A generalized inverse methodology, applied to individual pixel intensities in the sequence of auroral images, is used to constrain the model parameters. A uniformly bright auroral oval, and two non-uniform emission models were examined; one has an anomaly fixed to the System-III coordinate, and the other has an anomaly fixed in planet's local time. The latter has a broad and bright emission in the afternoon sector, and offers a significantly better fit in the south. Finally, a combination of the System-III fixed anomaly (equatorward of the oval) plus the local-time fixed anomaly (poleward) was found to simulate the emission intensities in both aurorae consistently well. The size of the auroral oval is larger in the north (by 10%) and smaller in the south (by 3-7%) compared to the O-6 model auroral oval. Weaker H: emissions are found both poleward and equatorward of the oval, the latter extending approximately to the footprint of the Io torus at most longitudes, System-III anomalies are tentatively identified at longitudes where the local magnetic field strength is less than that at the conjugate point. (C) 1996 Academic Press, Inc. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP Satoh, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 695,GREENBELT,MD 20771, USA. RI connerney, john/I-5127-2013 NR 40 TC 63 Z9 63 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1996 VL 122 IS 1 BP 1 EP 23 DI 10.1006/icar.1996.0106 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW654 UT WOS:A1996UW65400001 ER PT J AU Connerney, JEP Satoh, T Baron, RL AF Connerney, JEP Satoh, T Baron, RL TI Interpretation of auroral ''lightcurves'' with application to Jovian H-3(+) emissions SO ICARUS LA English DT Article ID HUBBLE-SPACE-TELESCOPE; MAGNETIC-FIELD; POLAR AURORA; UV AURORA; MU-M; JUPITER; ULTRAVIOLET; NORTH; H-3+; MAGNETOSPHERE AB Photometric observations of planetary aurorae may be used to constrain the time variation and spatial distribution of auroral emissions, thereby providing insight into planetary magnetic fields and magnetospheric dynamics. The variation of the total flux observed as a function of the planet's central meridian longitude(auroral ''lightcurve'') is used to estimate the parameters of a simple amoral emission model. An inverse methodology based upon the singular-value decomposition of a matrix is used to estimate the model parameters and to characterize the uniqueness of the solutions obtained. The method of analysis is applied to images of Jupiter's polar regions at a 3.4-mu m wavelength acquired during the first 4 months of 1992 using ProtoCAM at NASA's IRTF. The distribution and intensity of the H-3(+) emission in Jupiter's amoral regions are estimated from the auroral lightcurves and compared with analyses of the actual images. Northern and southern auroral intensities covary, and for episodes of more intense activity during the period of observation, intensities observed in the north polar region generally exceeded those observed in the south. Auroral intensity varies with time in a manner that suggests considerable change in charged particle precipitation in Jupiter's magnetosphere, and energy deposition in Jupiter's atmosphere, on a time scale of months. (C) 1996 Academic Press, Inc. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP Connerney, JEP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 695,GREENBELT,MD 20771, USA. RI connerney, john/I-5127-2013; OI connerney, jack/0000-0001-7478-6462 NR 29 TC 18 Z9 18 U1 1 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1996 VL 122 IS 1 BP 24 EP 35 DI 10.1006/icar.1996.0107 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW654 UT WOS:A1996UW65400002 ER PT J AU Moore, JM Mellon, MT Zent, AP AF Moore, JM Mellon, MT Zent, AP TI Mass wasting and ground collapse in terrains of volatile-rich deposits as a solar system-wide geological process: The pre-Galileo view SO ICARUS LA English DT Article ID POLAR LAYERED DEPOSITS; MARS; STABILITY; FEATURES; IO; DIFFUSION; VOYAGER-2; SURFACE; REGION; ICE AB The polar terrains of Mars are covered in many places with irregular pits and retreating scarps, as are some of the surfaces of the outer-planet satellites. These features are interpreted by us as diagnostic of exogenic degradation due to the loss of a volatile rock-forming matrix or cement, In this study we propose that sublimation degradation is a plausible Solar Systemwide geological process. Candidate examples have been identified on Mars, Io, and Triton, and possibly Europa and Ganymede. We envision this process as having two end-member expressions (pits and scarps), for which we hypothesize two end-member mechanisms (massive localized lenses and areally extensive basal layers), In this study we focus on the role this process may play on the surfaces of the galilean satellites, Our principle modeling results are that for these satellites, H2S, CO2, and NH3 are the only viable candidate volatiles for sublimation degradation of landforms, in light of galilean satellite cosmochemistry, For Io's polar regions only H2S, and then only from slopes that face the Sun and have thin lags, is volatile enough to cause the observed sublimation-induced erosion at those latitudes, SO2 is not a viable candidate as an agent of erosion, especially for these polar landforms. In the case of Europa, only CO2 and H2S are viable candidates (given surface age constraints). Both species could be efficient eroders in nonpolar regions. H2S could generate erosion within the polar regions if the deposition and erosion conditions were essentially identical as those we invoked for Io's polar regions, For Ganymede (and Callisto) NH3 might be an agent of erosion in equatorial terrains of great age, The sublimation of CO2 and H2S is much more robust than NH3, The much slower rate of sublimation degradation from NH3 might be detectable by Galileo and used as a compositional indicator. (C) 1996 Academic Press,Inc. RP Moore, JM (reprint author), NASA, AMES RES CTR, DIV SPACE SCI, MS 245-3, MOFFETT FIELD, CA 94035 USA. RI Mellon, Michael/C-3456-2016 NR 59 TC 28 Z9 28 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 JUL PY 1996 VL 122 IS 1 BP 63 EP 78 DI 10.1006/icar.1996.0109 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW654 UT WOS:A1996UW65400004 ER PT J AU Mosqueira, I AF Mosqueira, I TI Local simulations of perturbed dense planetary rings SO ICARUS LA English DT Article ID SATELLITE LINDBLAD RESONANCES; PARTICLE-SIZE DISTRIBUTIONS; SATURNS RINGS; COLLISIONAL SIMULATIONS; NUMERICAL-SIMULATION; RADIO OCCULTATION; URANIAN RINGS; DYNAMICS; DISKS; VOYAGER-2 AB Using a modified N-body code to include periodic boundary conditions in a perturbed shear flow, we investigate the role of viscosity on the dynamics of perturbed rings with optical depth tau similar to 1. In particular, we are concerned with rings such that q = a(de/da) not equal 0, where a is the semi-major axis and e is the eccentricity. We confirm the possibility that, for a sufficiently perturbed ring, the angular momentum luminosity may reverse direction with respect to the unperturbed ring (Borderies, N., P. Goldreich, and S. Tremaine 1983a. Icarus 55, 124-132). We use observationally constrained parameters for the delta and epsilon uranian rings, as well as the outer portion of Saturn's B ring. We find that understanding the effects of viscosity for the uranian rings requires that both local and non-local transport terms be considered if the coefficient of restitution experimentally obtained by Bridges et al. (Bridges, F. G., A. Hatzes, and D. N. C. Lin 1984. Nature 309, 333-335.) is appropriate for ring particles. We also find evidence that the criterion for viscous overstability is satisfied in the case of high optical depth rings, as originally proposed by Borderies et al. (Borderies, N., P. Goldreich, and S. Tremaine 1985. Icarus 63, 406-420.), making viscous overstability a leading candidate mechanism to explain the non-axisymmetric structure present in the outer portion of Saturn's B ring. To better understand our patch-code results eve extend a non-local and incompressible fluid model used by Borderies et al. for dense rings. We incorporate local and nonlocal transport terms as well as compressibility, while retaining the same number of arbitrary model parameters. (C) 1996 Academic Press, Inc. RP Mosqueira, I (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 45 TC 26 Z9 26 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1996 VL 122 IS 1 BP 128 EP 152 DI 10.1006/icar.1996.0115 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW654 UT WOS:A1996UW65400010 ER PT J AU Scoles, DL Hayden, JW Pickett, DF Rao, GM AF Scoles, DL Hayden, JW Pickett, DF Rao, GM TI The status of qualification of a new separator system for advanced aerospace battery cells SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB A nickel cadmium cell system which utilizes a polypropylene separator impregnated with polybenzimadazole, and which shows promise of providing an aerospace battery with performance equivalent to Super NiCd(TM), and yet is more cost effective, is described. Background information, cell construction information, detailed test program information and data, and status of qualification are given. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP Scoles, DL (reprint author), EAGLE PICHER POWER SYST DEPT,COLORADO SPRINGS,CO 80911, USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD JUL PY 1996 VL 11 IS 7 BP 27 EP 30 DI 10.1109/62.533969 PG 4 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA UV777 UT WOS:A1996UV77700007 ER PT J AU Yao, XS Maleki, L AF Yao, XS Maleki, L TI Optoelectronic oscillator for photonic systems SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article ID OPTICAL-INJECTION-LOCKING; DEVICES; LASERS; DIODE AB We describe a novel photonic oscillator that converts continuous-light energy into stable and spectrally pure microwave signals. This optoelectronic oscillator (OEO) consists of a pump laser and a feedback circuit including an intensity modulator, an optical-fiber delay line, a photodetector, an amplifier, and a filter. We present the results of a quasi-linear theory for describing the properties of the oscillator and their experimental verifications. Our findings indicate that the OEO can generate ultrastable, spectrally pure microwave-reference signals up to 75 GHz with a phase noise lower than -140 dBc/Hz at 10 KHz. We show that the OEO is a special voltage-controlled oscillator with an optical-output port and can be synchronized to a reference source by means of optical injection locking, electrical injection locking, and a phase-locked loop. Other OEO applications include high-frequency reference regeneration and distribution, high-gain frequency multiplication, comb frequency and pulse generation, carrier recovery, and clock recovery. RP CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NR 38 TC 193 Z9 198 U1 3 U2 28 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9197 EI 1558-1713 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD JUL PY 1996 VL 32 IS 7 BP 1141 EP 1149 DI 10.1109/3.517013 PG 9 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA UT427 UT WOS:A1996UT42700005 ER PT J AU Vorperian, V AF Vorperian, V TI The effect of the magnetizing inductance on the small-signal dynamics of the isolated Cuk converter SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article ID CONDUCTION MODE; PWM SWITCH AB The magnetizing inductance of the isolated Cuk converter introduces an undesirable pair of closely spaced complex zeros and poles, or a glitch, in the control-to-output transfer function. Limited analysis and experimentation in the past have shown that sufficient increase in the magnetizing inductance or manipulation of the ratio of the capacitances of the energy transfer capacitors can reduce the glitch. In this work, the isolated Cuk converter with coupled input and output inductors has been studied and the dependence of the glitch on various circuit parameters has been determined analytically A condition has been derived for the ratio of the capacitances of the two energy transfer capacitors which completely eliminates the glitch at a given operating point. With this condition satisfied, it is shown that the energy transfer capacitors can be easily damped by a simple RC network to eliminate the glitch from a wide range of operation about an operating point. RP Vorperian, V (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 303-300,PASADENA,CA 91109, USA. NR 11 TC 5 Z9 5 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD JUL PY 1996 VL 32 IS 3 BP 967 EP 983 DI 10.1109/7.532257 PG 17 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA UX978 UT WOS:A1996UX97800009 ER PT J AU Caylor, IJ Chandrasekar, V AF Caylor, IJ Chandrasekar, V TI Time-varying ice crystal orientation in thunderstorms observed with multiparameter radar SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID POLARIMETRIC RADAR; PRECIPITATION; PARTICLES; POLARIZATIONS; HYDROMETEORS AB Repeated changes associated with lightning have been observed with multiparameter radar in the echoes from the tops of Florida thunderstorms, These lightning-related radar signatures are interpreted as changes in the orientation of ice crystals being preferentially aligned parallel to the in-cloud electric field, The changes occur at intervals on the order of 10 s and are easily observed in the signatures of the differential propagation phase shift and the linear depolarization ratio which are sensitive to propagation effects caused by the oriented ice crystals, Orientation of ice crystals aloft has been previously observed using circularly polarized radar while the simultaneous differential phase shift and linear depolarization measurements reported here were obtained with a dual-linear polarized radar, The observations indicate crystal orientation angles greater than 45 degrees and occasionally near vertical, In one case, the crystals were found to be oriented in a layer near radar cloud top spanning a 20-km range and 3 km in depth. C1 COLORADO STATE UNIV,FT COLLINS,CO 80521. RP Caylor, IJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MESOSCALE ATMOSPHER PROC BRANCH,GREENBELT,MD 20771, USA. NR 35 TC 34 Z9 35 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1996 VL 34 IS 4 BP 847 EP 858 DI 10.1109/36.508402 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 VA165 UT WOS:A1996VA16500002 ER PT J AU Falco, T Francis, F Lovejoy, S Schertzer, D Kerman, B Drinkwater, M AF Falco, T Francis, F Lovejoy, S Schertzer, D Kerman, B Drinkwater, M TI Universal multifractal scaling of synthetic aperture radar images of sea-ice SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID RAIN; TURBULENCE; SURFACE; FIELDS; CLOUDS AB Multifrequency, multipolarization imaging radar scattering coefficient data sets, acquired by synthetic aperture radar (SAR) over sea-ice, were studied in order to reveal their scale-invariant properties; Two distinct scenes were acquired at C-band (5.6 cm) and L-band (25 cm) wavelengths for three different Linear polarizations (HH, VV, and HV), These sea-ice radar scattering coefficient fields were investigated by applying both Fourier and multifractal analysis techniques, The (multi) scaling of the data is clearly exhibited in both scenes for all three polarizations at L-band and for the HV polarization at C-band, The-fields presenting this symmetry were found to be well described by universal multifractals. The corresponding parameters alpha, C-1, and H were determined for all these fields and were found to vary little with only the parameter H (characterizing the degree of nonconservation) displaying some systematic sensitivity to polarization, The values found for the universal multifractal parameters are alpha approximate to 1.85 +/- 0.05, C-1 approximate to 0.0086 +/- 0.0041, and H approximate to -0.15 +/- 0.05. C1 UNIV PARIS 06, METEOROL DYNAM LAB, F-75005 PARIS, FRANCE. ATMOSPHER ENVIRONM SERV, BURLINGTON, ON L7R 4R6, CANADA. JET PROP LAB, PASADENA, CA 91109 USA. RP Falco, T (reprint author), MCGILL UNIV, DEPT PHYS, 3600 UNIV ST, MONTREAL, PQ H3A 2T8, CANADA. RI Lovejoy, Shaun/E-8019-2011 OI Lovejoy, Shaun/0000-0002-9367-3137 NR 43 TC 20 Z9 20 U1 0 U2 3 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 JUL PY 1996 VL 34 IS 4 BP 906 EP 914 DI 10.1109/36.508407 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA VA165 UT WOS:A1996VA16500007 ER PT J AU vandeGriend, AA Owe, M deRuiter, J Gouweleeuw, BT AF vandeGriend, AA Owe, M deRuiter, J Gouweleeuw, BT TI Measurement and behavior of dual-polarization vegetation optical depth and single scattering albedo at 1.4- and 5-GHz microwave frequencies SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID SMMR SATELLITE-OBSERVATIONS; SCALE SOIL-MOISTURE; EMISSION; GHZ AB A measurement procedure has been developed and tested to determine horizontal and vertical polarization radiative transfer properties, i.e., single scattering albedo (omega) and optical depth (tau), of vegetation under field conditions, The procedure was applied to a wheat crop for a series of biomass densities, The measurements were done using two different radiometers (1.4 and 5 GHz) and for different view angles, The measurements and calculations indicated that the ratios of horizontal and vertical polarization radiative transfer properties (alpha = Gamma(h)/Gamma(v), alpha' = tau(h)/tau(v) and beta = omega(h)/omega(v)) are slightly dependent on view angle. However, no significant dependence on biomass density could be discerned. C1 NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,GREENBELT,MD 20771. RP vandeGriend, AA (reprint author), VRIJE UNIV AMSTERDAM,INST EARTH SCI,DEPT HYDROL,DE BOELELAAN 1085,NL-1081 HV AMSTERDAM,NETHERLANDS. RI Gouweleeuw, Ben/A-8200-2012 NR 20 TC 35 Z9 35 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1996 VL 34 IS 4 BP 957 EP 965 DI 10.1109/36.508412 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA VA165 UT WOS:A1996VA16500012 ER PT J AU Ponchak, GE Dib, NI Katehi, LPB AF Ponchak, George E. Dib, Nihad I. Katehi, Linda P. B. TI Design and Analysis of Transitions from Rectangular Waveguide to Layered Ridge Dielectric Waveguide SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Transitions from rectangular waveguide to layered ridge dielectric waveguide are studied both experimentally and theoretically. In addition, a design procedure is given for each transition. The analysis and design procedures are valid for transitions between rectangular waveguide and other open dielectric waveguides such as image guide, insulated image guide, dielectric ridge guide, and inverted strip dielectric waveguide. It is shown that for small dielectric waveguides such as layered ridge dielectric waveguide, a transition which is comprised of a tapered ridge waveguide reduces the radiation loss by at least 1 dB. C1 [Ponchak, George E.] NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. [Dib, Nihad I.] Jordan Univ Sci & Technol, Dept Elect Engn, Irbid, Jordan. [Katehi, Linda P. B.] Univ Michigan, Elect Engn & Comp Syst Dept, Ann Arbor, MI 48109 USA. RP Ponchak, GE (reprint author), NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RI Dib, Nihad/M-4918-2015; OI Dib, Nihad/0000-0002-2263-5512 FU Army Research Office (ARO); NASA/Lewis Research Center FX This work was supported by the Army Research Office (ARO) and the NASA/Lewis Research Center Director's Discretionary Fund. NR 22 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 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUL PY 1996 VL 44 IS 7 BP 1032 EP 1040 AR PII S0018-9480(96)04703-5 DI 10.1109/22.508635 PN 1 PG 9 WC Engineering, Electrical & Electronic SC Engineering GA V28AX UT WOS:000208654800006 ER PT J AU Laskar, J Bautista, JJ Nishimoto, M Hamai, M Lai, R AF Laskar, J. Bautista, J. J. Nishimoto, M. Hamai, M. Lai, R. TI Development of Accurate On-Wafer, Cryogenic Characterization Techniques SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Significant advances in the development of high electron mobility field-effect transistors (HEMT's) have resulted in cryogenic, low-noise amplifiers (LNA's) whose noise temperatures are within an order of magnitude of the quantum noise limit (hv/k). Further advances in HEMT technology at cryogenic temperatures may eventually lead to the replacement of maser and superconducting-insulator-superconducting (SIS) front-ends in the 1-100 GHz frequency band. Key to identification of the best HEMT's and optimization of cryogenic LNA's is accurate and repeatable device measurements at cryogenic temperatures. A cryogenic on-wafer noise and scattering parameter measurement system has been developed to provide a systematic investigation of HEMT noise characteristics. In addition, an improved parameter extraction technique has been developed to help understand the relationship between device structure and LNA performance. C1 [Laskar, J.] Georgia Inst Technol, Sch Elect & Comp Engn, Atlanta, GA 30332 USA. [Bautista, J. J.] CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. [Nishimoto, M.; Hamai, M.; Lai, R.] TRW Elect Syst & Technol Div, Redondo Beach, CA 90278 USA. RP Laskar, J (reprint author), Georgia Inst Technol, Sch Elect & Comp Engn, Atlanta, GA 30332 USA. NR 23 TC 19 Z9 20 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUL PY 1996 VL 44 IS 7 BP 1178 EP 1183 AR PII S0018-9480(96)04728-X DI 10.1109/22.508659 PN 1 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA V28AX UT WOS:000208654800030 ER PT J AU Javadi, HHS Bowen, JG Rascoe, DL Romanofsky, RR Chorey, CM Bhasin, KB AF Javadi, HHS Bowen, JG Rascoe, DL Romanofsky, RR Chorey, CM Bhasin, KB TI Jet Propulsion Laboratory NASA Lewis Research Center space qualified hybrid high temperature superconducting/semiconducting 7.4 GHz low-noise downconverter for NRL HTSSE-II program SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB A deep space satellite downconverter receiver was proposed by Jet Propulsion Laboratory (JPL) and NASA Lewis Research Center (LeRC) for the Naval Research Laboratory's (NRL) high temperature superconductivity space experiment, phase-II (HTSSE-II) program, Space qualified low-noise cryogenic downconverter receivers utilizing thin-film high temperature superconducting (HTS) passive circuitry and semiconductor active devices were developed and delivered to NRL. The downconverter consists of an HTS preselect filter, a cryogenic low-noise amplifier, a cryogenic mixer, and a cryogenic oscillator with an HTS resonator, HTS components were inserted as the front-end filter and the local oscillator resonator for their superior 77 K performance over the conventional components, The semiconducting low noise amplifier also benefited from cooling to 77 K, The mixer was designed specifically for cryogenic applications and provided low conversion loss and low power consumption, In addition to an engineering model, two space qualified units (qualification, flight) were built and delivered to NRL, Manufacturing, integration and test of the space qualified downconverters adhered to the requirements of JPL class-D space instruments and partially to MIL-STD-883D specifications, The qualification unit has similar to 50 K system noise temperature which is a factor of three better than a conventional downconverter at room temperature, Commercial applications such as intersatellite links and V-SATS are envisioned to benefit by >3 dB link margin, or a factor of 2 in antenna size, from a future hybrid HTS/semiconducting cryogenic receiver employing new InP based HEMT LNA, In a spread spectrum communication network, the number of users per beam would more than double. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Javadi, HHS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 6 TC 7 Z9 7 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUL PY 1996 VL 44 IS 7 BP 1279 EP 1288 DI 10.1109/22.508232 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA UX545 UT WOS:A1996UX54500008 ER PT J AU Zak, M Meyers, RE AF Zak, M Meyers, RE TI Non-Newtonian effects in viscous flows SO INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS LA English DT Article AB Revision of the mathematical formalism of fluid dynamics suggests that some physical inconsistencies (infinite time of approaching equilibrium and fully deterministic solutions to the Navier-Stokes equations) can be removed by relaxing the Lipschitz conditions, i.e., the boundedness of the derivatives, in the constitutive equations. Physically such a modification can be interpreted as an incorporation of an infinitesimal static friction in the constitutive law. A modified version of the Navier-Stokes equations is introduced, discussed, and illustrated by examples. It is demonstrated that all the new effects in the modified model emerge within vanishingly small neighborhoods of equilibrium states which are the only domains where the governing equations are different from classical. C1 USA,RES LAB,WHITE SANDS MISSILE RANGE,NM 88002. RP Zak, M (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0020-7748 J9 INT J THEOR PHYS JI Int. J. Theor. Phys. PD JUL PY 1996 VL 35 IS 7 BP 1423 EP 1460 DI 10.1007/BF02084951 PG 38 WC Physics, Multidisciplinary SC Physics GA VA925 UT WOS:A1996VA92500013 ER PT J AU Kowbel, W Chellappa, V Withers, JC Ransone, PO AF Kowbel, W Chellappa, V Withers, JC Ransone, PO TI Applications of net-shape molded carbon-carbon composites in IC engines SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB Unique thermal and mechanical properties of carbon-carbon (C-C) composites make them suitable for internal combustion (IC) engine applications. However, the current high manufacturing cost of C-C composites greatly limits their commercial applications. Recent advances in C-C composites manufacturing technologies offer a potentially low cost ($50/lb) material. Thus, forming controlling the application of low cost C-C composites in the IC engines. This paper demonstrates the feasibility of using low-cost, molded C-C composites in spark ignition engine applications such as pistons and valves. Problem areas in IC applications of C-C composites are addressed together with a cost estimate to produce C-C pistons at high volume. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP Kowbel, W (reprint author), MER CORP,TUCSON,AZ, USA. NR 7 TC 6 Z9 9 U1 0 U2 1 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD JUL PY 1996 VL 27 IS 4 BP 2 EP 7 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA VJ732 UT WOS:A1996VJ73200001 ER PT J AU Hou, TH Johnston, NJ Weiser, ES Marchello, JM AF Hou, TH Johnston, NJ Weiser, ES Marchello, JM TI IM7/LaRC(TM)-IAX polyimide composites SO JOURNAL OF ADVANCED MATERIALS LA English DT Article ID CRYSTALLIZATION AB LaRC(TM)-IAX (Langley Research Center - Improved Adhesive eXperimental Resin) aromatic polyimide is based on oxydiphthalic anhydride and 90:10 ratio of 3,4'-oxydianiline and 1,4-phenylenediamine. To evaluate the powder-form of this material as a matrix for high performance composites, three LaRC(TM)-IAX powders were prepared with three, four, and five percent stoichiometric imbalance via end-capping with phthalic anhydride, affording theoretical number average molecular weights of 15,892, 11,858, and 9,438 g/mol, respectively. Thermal and rheological properties and the residual solvent content of the three powders were obtained. Unidirectional IM7 powder-coated towpreg made from each of the three resins was frame-wrapped and consolidated into unidirectional laminates. With slight modification, the consolidation cycle developed previously for IM7/LaRC(TM)-IAX solution-coated composites was found to be equally applicable for IM7/LaRC(TM)-IAX powder-coated composites. Composite mechanical properties were obtained and processing and property relationships were established. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. OLD DOMINION UNIV,NORFOLK,VA. RP Hou, TH (reprint author), LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666, USA. NR 15 TC 4 Z9 5 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD JUL PY 1996 VL 27 IS 4 BP 37 EP 46 PG 10 WC Materials Science, Multidisciplinary SC Materials Science GA VJ732 UT WOS:A1996VJ73200006 ER PT J AU Mehta, UB AF Mehta, UB TI Strategy for developing air-breathing aerospace planes (vol 33, pg 377, 1996) SO JOURNAL OF AIRCRAFT LA English DT Correction, Addition RP Mehta, UB (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 3 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1996 VL 33 IS 4 BP 840 EP 840 DI 10.2514/3.56938 PG 1 WC Engineering, Aerospace SC Engineering GA VD917 UT WOS:A1996VD91700027 ER PT J AU Druyan, LM Hall, TM AF Druyan, LM Hall, TM TI The sensitivity of African wave disturbances to remote forcing SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article; Proceedings Paper CT Jehuda Neumann Memorial Symposium on Mesoscale Modeling and Climate History CY JAN 04-06, 1995 CL JERUSALEM, ISRAEL ID SEA-SURFACE TEMPERATURES; SUB-SAHARAN DROUGHT; SAHEL RAINFALL; NORTHERN SUMMER; EASTERLY WAVES; ATLANTIC; MONSOONS AB Ensembles of three simulations each, forced by June-September 1987 and 1988 sea surface temperatures, respectively, were made with a new version of the general circulation model of the National Aeronautics and Space Administration/Goddard Institute for Space Studies. Time series of 6-h meridional winds at about 780 mb over West Africa were spectrally analyzed to detect African wave disturbances, whose properties for the two ensembles are compared and contrasted. The realistically simulated, stronger 1988 tropical easterly jet and the associated stronger upper-tropospheric divergence are components of interannual differences in the SST-forced planetary circulation, which correspond to higher amplitudes of African wave activity and concomitant excesses in 1988 Sahel rainfall rates. Results do not show. however, that most of the heavier precipitation was spatially organized by African wave structures. The excess rainfall is associated with stronger mean southerly circulation in the lower troposphere, which carried more moisture into the Sahel. Nevertheless, because waves modulate winds, convergence, humidity, and precipitation, the study suggests that they serve as a teleconnection mechanism, whereby extreme Pacific Ocean SST anomalies art: able to influence climate variability in Africa's Sahel. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. LAB MODELISAT CLIMAT & ENVIRONNMENT,GIF SUR YVETTE,FRANCE. RP Druyan, LM (reprint author), COLUMBIA UNIV,CTR CLIMATE SYST RES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 31 TC 18 Z9 18 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD JUL PY 1996 VL 35 IS 7 BP 1100 EP 1110 DI 10.1175/1520-0450(1996)035<1100:TSOAWD>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UV295 UT WOS:A1996UV29500008 ER PT J AU Su, CH Sha, YG Mazuruk, K Lehoczky, SL AF Su, CH Sha, YG Mazuruk, K Lehoczky, SL TI Phase diagram of HgTe-ZnTe pseudobinary and density, heat capacity, and enthalpy of mixing of Hg1-xZnxTe pseudobinary melts SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID MERCURY ZINC TELLURIDE; ALLOYS; MICROHARDNESS; HG1-XCDXTE; GROWTH; HGZNTE; SEMICONDUCTORS; EPITAXY AB In this article, the solidus temperatures of the Hg1-xZnxTe pseudobinary phase diagram for several compositions in the low x region were measured by differential thermal analysis and the HgTe-ZnTe pseudobinary phase diagram was constructed. The densities of two HgZnTe melts, x=0.10 and 0.16, were determined by an in situ pycnometric technique in a transparent furnace over, respectively, 110 and 50 degrees C ranges of temperature. The thermodynamic properties of the melts, such as the heat capacity and enthalpy of mixing, were calculated for temperatures between the liquidus and 1500 degrees C by assuming an associated solution model for the liquid phase. RP Su, CH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 32 TC 7 Z9 7 U1 1 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUL 1 PY 1996 VL 80 IS 1 BP 137 EP 142 DI 10.1063/1.362826 PG 6 WC Physics, Applied SC Physics GA UU532 UT WOS:A1996UU53200020 ER PT J AU Sulzman, FM AF Sulzman, FM TI Life sciences space missions - Overview SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Review DE weightlessness; space research; Spacelab Life Sciences missions; Bion; Spacelab; microgravity ID SUSTAINED MICROGRAVITY; PULMONARY AB It has been known for many years that weightlessness induces changes in numerous physiological systems: the cardiovascular system declines in both aerobic capacity and orthostatic tolerance; there is a reduction in fluid and electrolyte balance, hematocrit, and certain immune parameters; bone and muscle mass and strength are reduced; various neurological responses include space motion sickness and posture and gate alterations. These responses are caused by the hypokinesia of weightlessness, the cephalic fluid shift, the unloading of the vestibular system, stress, and the altered temporal environment. RP Sulzman, FM (reprint author), NASA,DEPT LIFE SCI,CODE UL,800 E ST SW,WASHINGTON,DC 20546, USA. NR 26 TC 19 Z9 19 U1 1 U2 2 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD JUL PY 1996 VL 81 IS 1 BP 3 EP 6 PG 4 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA VA586 UT WOS:A1996VA58600001 PM 8828641 ER PT J AU Alfrey, CP Udden, MM LeachHuntoon, C Driscoll, T Pickett, MH AF Alfrey, CP Udden, MM LeachHuntoon, C Driscoll, T Pickett, MH TI Control of red blood cell mass in spaceflight SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE plasma volume; erythropoietin; erythron iron turnover; red blood cell survival; growth factor; cytokine; cytoadhesion ID ERYTHROPOIETIN AB The effect of spaceflight on red blood cell mass (RBCM), plasma volume (PV) erythron iran turnover, serum erythropoietin, and red blood cell (RBC) production and survival and indexes were determined for six astronauts on two shuttle missions, 9 and 14 days in duration. respectively. PV decreased within tile first day. RBCM decreased because of destruction of RBCs either newly released or scheduled to be released from the bone marrow. Older RBCs survived normally. On return to Earth, plasma volume increased, hemoglobin concentration and RBC count declined, and serum erythropoietin increased. We propose that entry into microgravity results in acute plethora as a result of a decrease in vascular space. FV decreases, causing an increase in hemoglobin concentration that effects a decrease in crythropoietin or other growth factors or cytokines. The RBCM decreases by destruction of recently formed RBCs to a level appropriate ibr the microgravity environment. Return to Earth results sequentially in acute hypovolemia as vascular space dependent on gravity is refilled, an increase in plasma volume, a decrease in hemoglobin concentration (anemia), and an increase in serum erythropoietin. C1 BAYLOR COLL MED,DEPT MED,HOUSTON,TX 77030. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77030. GULF COAST REG BLOOD CTR,HOUSTON,TX 77054. NR 17 TC 141 Z9 146 U1 1 U2 5 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD JUL PY 1996 VL 81 IS 1 BP 98 EP 104 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA VA586 UT WOS:A1996VA58600011 PM 8828651 ER PT J AU Leach, CS Alfrey, CP Suki, WN Leonard, JI Rambaut, PC Inners, LD Smith, SM Lane, HW Krauhs, JM AF Leach, CS Alfrey, CP Suki, WN Leonard, JI Rambaut, PC Inners, LD Smith, SM Lane, HW Krauhs, JM TI Regulation of body fluid compartments during short-term spaceflight SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE total body water; glomerular filtration rate; plasma volume; fluid intake; extracellular fluid ID MICROGRAVITY; PLASMA; SHIFTS; RADIOIMMUNOASSAY; WEIGHTLESSNESS; VASOPRESSIN; TISSUES; SPACE; BLOOD; WATER AB The fluid and electrolyte regulation experiment with seven subjects was designed to describe body fluid, renal, and fluid regulatory hormone responses during the Spacelab Life Sciences-1 (9 days) and -2 (14 days) missions. Total body water did not change significantly. Plasma volume (PV; P < 0.05) and extracellular fluid volume (ECFV; P < 0.10) decreased 21 h after launch, remaining below preflight levels until after landing. Fluid intake decreased during weightlessness, and glomerular filtration rate (GFR) increased in the first 2 days and on days 8 (P < 0.05). Urinary antidiuretic hormone (ADH) excretion increased (P < 0.05) and fluid excretion decreased early in flight (P < 0.10). Plasma renin activity (PRA; P < 0.10) and aldosterone (P < 0.05) decreased in the first few hours after launch; PRA increased 1 wk later (P < 0.05). During flight, plasma atrial natriuretic peptide concentrations were consistently lower than preflight means, and urinary cortisol excretion was usually greater than preflight levels. Acceleration at launch and landing probably caused increases in ADH and cortisol excretion, and a shift of fluid from the extracellular to the intracellular compartment would account for reductions in ECFV. Increased permeability of capillary membranes may be the most important mechanism causing spaceflight-induced PV reduction, which is probably maintained by increased GFR and other mechanisms. If the Gauer-Henry reflex operates during spaceflight, it must be completed within the first 21 h of flight and be succeeded by establishment of a reduced PV set point. C1 KRUG LIFE SCI,HOUSTON,TX 77058. BAYLOR COLL MED,HOUSTON,TX 77030. UNIFORMED SERV UNIV HLTH SCI,BETHESDA,MD 20814. N ATLANTIC TREATY ORG,B-1110 BRUSSELS,BELGIUM. RP Leach, CS (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV MED SCI,BIOMED OPERAT & RES BRANCH,MAIL CODE AA,HOUSTON,TX 77058, USA. NR 49 TC 186 Z9 194 U1 1 U2 7 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD JUL PY 1996 VL 81 IS 1 BP 105 EP 116 PG 12 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA VA586 UT WOS:A1996VA58600012 PM 8828652 ER PT J AU Allen, DL Yasui, W Tanaka, T Ohira, Y Nagaoka, S Sekiguchi, C Hinds, WE Roy, RR Edgerton, VR AF Allen, DL Yasui, W Tanaka, T Ohira, Y Nagaoka, S Sekiguchi, C Hinds, WE Roy, RR Edgerton, VR TI Myonuclear number and myosin heavy chain expression in rat soleus single muscle fibers after spaceflight SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE microgravity; deoxyribonucleic acid unit; myonuclear domain size ID MAMMALIAN SKELETAL-MUSCLE; HINDLIMB SUSPENSION; SATELLITE CELLS; SLOW; PROTEINS; ISOFORM AB The effects of 14 days of spaceflight on myonuclear number, fiber size, and myosin heavy chain (MHC) expression in isolated rat soleus muscle fiber segments were studied. Single soleus muscle fibers from rats flown on the Spacelab Life Sciences-2 14-day mission were compared with those from age-matched ground-based control rats by using confocal microscopy and gel electrophoresis. Spaceflight resulted in a significant reduction in the number of fibers expressing type I MHC and an increase in the number of fibers expressing type IIx or IIa MHC. Spaceflight also resulted in an increase in the percentage of fibers coexpressing more than one MHC and in the reexpression of the neonatal isoform of MHC in some fibers. Fiber cross-sectional area was significantly reduced in pure type I MHC-expressing fibers and in fibers coexpressing type I+II MHC but not in fibers expressing one or more type II MHC in the flight rats. The number of myonuclei per millimeter was significantly reduced in type I MHC-expressing fibers from the flight rats but was not significantly different in type I+II and type II MHC-coexpressing fibers. Fibers expressing neonatal MHC were similar in size to control fibers but had significantly fewer myonuclei per millimeter than flight fibers not expressing neonatal MHC. In type I MHC-expressing fibers, the reduction in fiber cross-sectional area was greater than the reduction in myonuclear number; thus the average cytoplasmic volume per myonucleus was significantly lower in flight than in control fibers. The reduction in both myonuclear number and fiber size of fibers expressing type I MHC after 14 days of spaceflight supports the hypothesis that changes in the number of myonuclei may be a contributing factor to the reduction in fiber size associated with chronic unloading of the musculature. C1 NATL INST FITNESS & SPORTS,DEPT PHYSIOL & BIOMECH,KAGOSHIMA 89123,JAPAN. UNIV CALIF LOS ANGELES,DEPT PHYSIOL SCI,LOS ANGELES,CA 90095. UNIV CALIF LOS ANGELES,BRAIN RES INST,LOS ANGELES,CA 90095. NASA,AMES RES CTR,SPACE LIFE SCI PAYLOAD OFF,MOFFETT FIELD,CA 94035. NATL SPACE DEV AGCY JAPAN,SPACE EXPT GRP,TSUKUBA,IBARAKI 305,JAPAN. FU NINDS NIH HHS [NS-16333] NR 35 TC 137 Z9 140 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD JUL PY 1996 VL 81 IS 1 BP 145 EP 151 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA VA586 UT WOS:A1996VA58600016 PM 8828656 ER PT J AU Ohira, Y Yasui, W Kariya, F Tanaka, T Kitajima, I Maruyama, I Nagaoka, S Sekiguchi, C Hinds, WE AF Ohira, Y Yasui, W Kariya, F Tanaka, T Kitajima, I Maruyama, I Nagaoka, S Sekiguchi, C Hinds, WE TI Spaceflight effects on beta-adrenoceptor and metabolic properties in rat plantaris SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE spaceflight; rat plantaris; beta-adrenoceptor; mitochondrial enzymes; fiber type ID SKELETAL-MUSCLE; ADRENERGIC RECEPTORS; HINDLIMB SUSPENSION; FIBER TYPE; SOLEUS; ELECTROMYOGRAPHY; GASTROCNEMIUS; CONTRACTILE; BINDING AB Effects of 14 days of spaceflight on beta-adrenoceptor (beta-AR), mitochondrial enzyme activities, and fiber type composition were studied in plantaris muscles of male adult Sprague-Dawley rats. The beta-AR was analyzed in cross sections by quantitative autoradiography. The maximum binding capacity (B-max) of beta-AR was significantly lowered (similar to 29%) after flight, but the recovery was not completed within 9 days in 1-G environment. Because the dissociation constant remained unchanged, it is suggested that the changes in the B-max were caused by the alteration of receptor number: The activities of succinate dehydrogenase (SDH) measured in whole homogenates were subnormal (approximately -24%) in muscles sampled similar to 5 B after flight but they were normalized during 9 days of recovery, The percent composition of fiber types and beta-hydroxyacyl CoA dehydrogenase (HAD) activity did not change significantly due to spaceflight. It is suggested that the spaceflight-induced decrease of the B-max of beta-AR in plantaris was accompanied by a lowered activity of a mitochondrial inner-membrane enzyme SDH but not a matrix enzyme HAD. C1 KAGOSHIMA UNIV,SCH MED,DEPT MOL LAB MED,KAGOSHIMA 890,JAPAN. NATL SPACE DEV AGCY JAPAN,SPACE EXPT GRP,TSUKUBA,IBARAKI 305,JAPAN. NASA,AMES RES CTR,SPACE LIFE SCI PAYLOAD OFF,MOFFETT FIELD,CA 94035. RP Ohira, Y (reprint author), NATL INST FITNESS & SPORTS,DEPT PHYSIOL & BIOMECH,SHIROMIZU CHO 1,KAGOSHIMA 89123,JAPAN. NR 29 TC 13 Z9 13 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD JUL PY 1996 VL 81 IS 1 BP 152 EP 155 PG 4 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA VA586 UT WOS:A1996VA58600017 PM 8828657 ER PT J AU Lesnyak, A Sonnenfeld, G Avery, L Konstantinova, I Rykova, M Meshkov, D Orlova, T AF Lesnyak, A Sonnenfeld, G Avery, L Konstantinova, I Rykova, M Meshkov, D Orlova, T TI Effect of SLS-2 spaceflight on immunologic parameters of rats SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE spaceflight; T lymphocytes; natural killers; immunity parameters; cytokines ID IMMUNE CHANGES; DURATION MISSIONS; SPACE-FLIGHT AB During the Spacelab Life Sciences-2 mission, rats were dissected in space and biosamples were returned to Earth for analysis, Immunologic studies addressed the kinetics of T lymphocyte proliferative responses, cytotoxic activity of natural killer cells, and cytokine production. Experiments were performed by using spleen and bone marrow of rats dissected before flight, during flight, immediately after landing of the space shuttle (R + O), or 14 days after landing (R + 14), as well as those of respective control animals. Each group consisted of five male Sprague-Dawley rats. It was demonstrated that T lymphocyte activity of rats dissected in flight was significantly decreased compared with the controls. This was observed during 48-, 72-, and 96-h cultivation and stimulation with the following mitogenic stimuli: concanavalin A (Con A; 0.1, 1.0, and 10.0 mg/ml), phytohemagglutinin (PHA; 2.5 mg/ml), and interleukin-2 (IL-2; 1 U/ml). The cell proliferation rate in rats dissected immediately after landing did not decrease, whereas that in rats dissected at R + 14 increased. The activity of spleen natural killer cells was reduced in response to Cr-51-labeled target cells during flight (YAC-1 and K-562) and after flight (YAC-1). At R + 14, their activity returned to normal. Another technique employed to measure natural cytotoxicity, using [H-3]uridine-labeled target cells and ribonuclease, did not reveal any differences between control and experimental groups. In bone marrow, the activity of natural killer cells did not vary significantly. The production of IL-1, IL-2, tumor necrosis factor (TNF)-alpha, and TNF-beta in spleen cell cultures of the flight rats was reduced. At R + O, IL-1 and TNF-P levels remained lowered, whereas TNF-alpha was increased. At R + O, interferon-alpha and interferon-gamma levels were diminished. In summary, cell-mediated immunity in rats was significantly suppressed during flight. The lime course variation of immune parameters after flight suggests that tile changes may truly indicate a response of the immune system to spaceflight conditions that could increase over time. C1 CAROLINAS MED CTR,DEPT GEN SURG RES,CHARLOTTE,NC 28232. STATE RES CTR,INST BIOMED PROBLEMS,MOSCOW 123007,RUSSIA. NF GAMALEI INST EPIDEMIOL & MICROBIOL,MOSCOW,RUSSIA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Meshkov, Dmitry/E-5757-2016 OI Meshkov, Dmitry/0000-0001-6474-7427 NR 16 TC 38 Z9 39 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD JUL PY 1996 VL 81 IS 1 BP 178 EP 182 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA VA586 UT WOS:A1996VA58600021 PM 8828661 ER PT J AU Korolkov, V Helwig, D Viso, M Connolly, J AF Korolkov, V Helwig, D Viso, M Connolly, J TI Overview SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Review DE rhesus monkey; space research; weightlessness AB The Cos mos 2229 unmanned biosatellite was launched from the Plesetsk Cosmodrome in northern Russia on December 29, 1992. This was tile 10th Russia-sponsored international mission dedicated to space biology and marked the 8th mission with United States participation. The payload, which orbited the Earth for 11 days 16 h, included two rhesus monkeys, the papers that follow report studies on these monkeys. C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. LOCKHEED MARTIN ENGN & SCI SERV,MOFFETT FIELD,CA 94035. CTR NATL ETUD SPATIALES,F-75039 PARIS 01,FRANCE. MINIST PUBL HLTH RUSSIA,INST BIOMED PROBLEMS,MOSCOW 123007,RUSSIA. NR 5 TC 6 Z9 6 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD JUL PY 1996 VL 81 IS 1 BP 186 EP 187 PG 2 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA VA586 UT WOS:A1996VA58600023 PM 8828663 ER PT J AU Roy, RR Tri, C Grossman, EJ Talmadge, RJ Grindeland, RE Mukku, VR Edgerton, VR AF Roy, RR Tri, C Grossman, EJ Talmadge, RJ Grindeland, RE Mukku, VR Edgerton, VR TI IGF-I, growth hormone, and/or exercise effects on non-weight-bearing soleus of hypophysectomized rats SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE fiber types; fiber size; muscle atrophy; countermeasures; simulated microgravity; growth factors; insulin-like growth factor I ID MESSENGER-RIBONUCLEIC-ACID; SKELETAL-MUSCLE; HINDLIMB SUSPENSION; ANABOLIC-STEROIDS; BINDING-PROTEINS; GENE-EXPRESSION; SUSPENDED RATS; SOMATOMEDIN-C; HUMAN-SERUM; FIBERS AB The effects of insulin-like growth factor (IGF-I) or growth hormone (GH) with and without exercise on predominantly slow muscles of hypophysectomized hindlimb-suspended (HS) rats were determined. IIS resulted in a 21, 23, and 30% decrease in soleus, adductor longus, and vastus intermedius masses, respectively, compared with ambulatory rats. Compared with values in IIS rats, IGF-I increased the vastus intermedius mass and GH or Exercise alone increased both tile soleus and vastus intermedius masses. There was a strong interactive effect between GI-I, but not IGF-I, and exercise in all three muscles of HS rats. The soleus fiber type distribution of IIS rats was not affected by any treatment. HS resulted in a 24, 18 (P > 0.05), 32, and 20% (P > 0.05) decrease in the size of soleus fibers containing type I, IIa, I+IIa, and IIa+IIx myosin heavy chains, respectively, compared with ambulatory hypophysectomized rats. Hormone or exercise alone had no effect on fiber size in HS rats. However, all fiber sizes (except for type IIa+IIx in ICF-I with exercise rats were larger In IIS rats treated with GH or IGF-I and exercise than those in HS rats. These data indicate an interactive effect of both GH and IGF-I with exercise in maintaining fiber size of chronically nonweight-bearing predominantly slow muscles. Further more, the results suggest that the myosin heavy-chain phenotype in rats deficient in all pituitary factors is unresponsive to short-term administration of either GH or IGF-I or to exercise or HS. C1 UNIV CALIF LOS ANGELES,DEPT PHYSIOL SCI,LOS ANGELES,CA 90095. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. GENENTECH INC,S SAN FRANCISCO,CA 94080. RP Roy, RR (reprint author), UNIV CALIF LOS ANGELES,SCH MED,BRAIN RES INST,CTR HLTH SCI,10833 LE CONTE AVE,LOS ANGELES,CA 90095, USA. FU NINDS NIH HHS [NS-16333] NR 48 TC 30 Z9 30 U1 0 U2 2 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD JUL PY 1996 VL 81 IS 1 BP 302 EP 311 PG 10 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA VA586 UT WOS:A1996VA58600038 PM 8828678 ER PT J AU Tai, H AF Tai, H TI Equivalent thermal conductivity of two- and three-dimensional orthogonally fiber-reinforced composites in one-dimensional heat flow SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE thermal conductivity; heat flow; fiber-reinforced composites ID BOUNDS AB By applying the fundamental definition of thermal conductivity to a unit cell of an orthogonal fiber-reinforced composite material in a one-dimensional heat flow, one can readily deduce simple mathematical expressions for the equivalent thermal conductivity for the composite material. Such expressions can serve as useful guides for materials development. RP Tai, H (reprint author), NASA,LANGLEY RES CTR,AST,HAMPTON,VA 23681, USA. NR 22 TC 18 Z9 18 U1 0 U2 1 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD JUL PY 1996 VL 18 IS 3 BP 221 EP 227 PG 7 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA VD570 UT WOS:A1996VD57000007 ER PT J AU Hamm, RA Chandrasekhar, S Lunardi, L Geva, M Malik, R Humphrey, D Ryan, R AF Hamm, RA Chandrasekhar, S Lunardi, L Geva, M Malik, R Humphrey, D Ryan, R TI Materials and electrical characteristics of carbon-doped Ga0.47In0.53As using carbontetrabromide by MOMBE for HBT device applications SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 5th International Conference on Chemical Beam Epitaxy and Related Growth Techniques (ICCBE-5) CY AUG 14-16, 1995 CL UNIV CALIF SAN DIEGO, SAN DIEGO, CA HO UNIV CALIF SAN DIEGO ID MOLECULAR-BEAM EPITAXY; HETEROJUNCTION BIPOLAR-TRANSISTORS; BERYLLIUM; INGAAS; GAAS; INP AB Metalorganic molecular beam epitaxy (MOMBE) growth of C-doped Ga0.47In0.53As heterostructures and Ga0.47In0.53As/InP heterostructure bipolar transistors (HBT) using carbontetrabromide (CBr4) as the dopant source is reported. Hall, secondary ion mass spectrometry (SIMS), and X-ray data were used to characterize the bulk C-Ga0.47In0.53As material. The incorporation of C showed a poser dependence on the group V beam flux of -0.29 and -0.75 for solid arsenic and AsH3 sources, respectively. This may be related to the change in group V vacancy concentration as the group V beam flux is varied. X-ray measurements of C-doped layers indicated a contraction in the lattice parameter larger than would be calculated using Vegard's law. Doping levels from 2 x 10(17) to 7 x 10(19) cm(-3) were measured with mobilities ranging cm from 105 to 40 cm(2)/V . s, respectively. SIMS data showed very abrupt profiles with no apparent memory effects. Hydrogen was also measured in the layers and annealing of samples in vacuum showed an increase in doping, of at most 50%, only for samples grown at lower temperatures, about 450 degrees C. For most samples, however, an increase in the mobility was measured after annealing, indicating that the neutral C-H complexes most likely contribute to the majority carrier scattering Large area devices with varying base thickness, W-B, and base doping, p, were fabricated. Devices showed good Gummel characteristics with n(c) = 1.15 and n(b) = 1.17. The gain variation for different devices was found to be proportional to 1/(W(B)p)(2), which is consistent with a diffusive base transport and Auger-dominated recombination in the heavily doped base region. A comparison with Be-doped devices showed the same trend with slightly higher gains. It was also observed that in devices where the C-doped base was grown at temperatures > 500 degrees C the gain was shifted to much lower values. Small devices were also fabricated and measured with f(T) and f(max) values of 70 and 50 GHz, respectively. C1 AT&T BELL LABS,HOLMDEL,NJ 07733. AT&T BELL LABS,BREINIGSVILLE,PA 19031. JPL,PASADENA,CA. RP Hamm, RA (reprint author), AT&T BELL LABS,600 MT AVE,MURRAY HILL,NJ 07974, USA. RI Schaff, William/B-5839-2009 NR 21 TC 15 Z9 15 U1 0 U2 7 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 JUL PY 1996 VL 164 IS 1-4 BP 362 EP 370 DI 10.1016/0022-0248(96)00004-8 PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA UY960 UT WOS:A1996UY96000058 ER PT J AU Maurice, S Sittler, EC Cooper, JF Mauk, BH Blanc, M Selesnick, RS AF Maurice, S Sittler, EC Cooper, JF Mauk, BH Blanc, M Selesnick, RS TI Comprehensive analysis of electron observations at Saturn: Voyager 1 and 2 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ENERGETIC PARTICLES; PLASMA OBSERVATIONS; CHARGED-PARTICLES; MAGNETOSPHERE; MICROSIGNATURES; SATELLITES; SPACECRAFT; MODEL; IONS AB We present a comprehensive analysis of Voyager 1 and 2 electron observations within Saturn's magnetosphere. This analysis entails the merging of electron observations from the Plasma Science (PLS) experiment, the Low Energy Charged Particle (LECP) experiment and the Cosmic Ray System (CRS) experiment. For each encounter, the three instruments combined allow us to compute the electron energy spectra over a wide range of energies from 10 eV to similar to 2 MeV between the closest approaches and L = 18.5. The instruments use different technologies, different sensitivities, and different fields of view; however, we observe a surprisingly good matching of the data sets on a 15-min timescale. The PLS-LECP-CRS spectra include the low-energy thermal component of the magnetospheric plasma, the keV suprathermal electrons, and the high-energy tail extending into the MeV energy range. From the combined spectra, we compute a comprehensive set of macroscopic parameters (electron density, pressure, beta factor, and electron current at the spacecraft): the analysis reveals a variety of radial gradients for these quantities and the corresponding electron populations. We also compute phase space densities over a wide range in energy and radial distances, analyzing local time symmetries, electron source distributions, and temporal variations of Saturn's magnetosphere. The ultimate goal of this study is to provide a comprehensive empirical model of the charged particle population within Saturn's magnetosphere. It will be used to support the development of the Cassini mission and to allow detailed planning of the tour design with regard to charged particle science and radiation hazards. C1 OBSERV MIDI PYRENEES,LAB ASTROPHYS TOULOUSE,F-31400 TOULOUSE,FRANCE. GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,SPACE PHYS DATA FACIL,GREENBELT,MD 20771. JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20707. CALTECH,PASADENA,CA 91125. GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP Maurice, S (reprint author), EUROPEAN SPACE AGCY,ESTEC,DEPT SPACE SCI,2200 AG NOORDWIJK,NETHERLANDS. RI Cooper, John/D-4709-2012; Mauk, Barry/E-8420-2017 OI Mauk, Barry/0000-0001-9789-3797 NR 44 TC 30 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1996 VL 101 IS A7 BP 15211 EP 15232 DI 10.1029/96JA00765 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV415 UT WOS:A1996UV41500002 ER PT J AU Sotirelis, T AF Sotirelis, T TI The shape and field of the magnetopause as determined from pressure balance SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; MODELS AB This article presents a theoretical study of the dependence of the magnetopause shape and field on the dynamic pressure of the solar wind. The magnetopause surface (assumed to be axisymmetric) is determined by requiring the plasma pressure outside, estimated by the ''Newtonian approximation,'' to be balanced by the magnetic pressure inside, The magnetic field inside is given by the sum of (1) the Earth's internal field, (2) the field from various magnetospheric current systems (cross-tail current, ring current, etc.) as given by an empirical model, and (3) the field due to magnetopause currents. The magnetopause field is a function of the magnetopause shape and is updated each time this shape is adjusted toward pressure balance. In previous studies of this kind, only dipole and magnetopause fields were incorporated. This is the first three-dimensional solution of the problem to include the cross-tail current and thus to obtain a realistic magnetotail configuration. The results of this study are twofold. First, the shape of the magnetopause surface is computed under a variety of conditions. The resulting shapes are compared with fits to observed magnetopause crossings, and the scaling of magnetopause position on solar wind dynamic pressure is determined, Second, the model that results can be viewed as an improved version of the empirical model that was used as input, in that the magnetic field in the vicinity of the magnetopause (where empirical models have less guidance from data) is made more realistic. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. NR 24 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1996 VL 101 IS A7 BP 15255 EP 15264 DI 10.1029/96JA01084 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV415 UT WOS:A1996UV41500004 ER PT J AU Ho, CM Tsurutani, BT Smith, EJ Feldman, WC AF Ho, CM Tsurutani, BT Smith, EJ Feldman, WC TI Properties of slow-mode shocks in the distant (>200 R(E)) geomagnetic tail SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SHEET BOUNDARY-LAYER; PLASMA SHEET; MAGNETOTAIL; ISEE-3; INSTABILITY AB The two distant ISEE 3 geomagnetic tail passes have been examined to identify all slow-mode shocks present in the data. We find a total of 86 events from 439 plasma sheet/lobe crossings, using five criteria based on relations between the upstream lobe and the downstream plasma sheet magnetic field and plasma measurements. The statistical results of slow-mode shock parameters such as the angle between magnetic field and shock normal, theta(Bn), Alfven Mach number along the normal direction, M(An), and electron beta, beta(e), are calculated and reported. On average, the magnetic field decreases by a factor similar to 2.7, the electron density increases by similar to 1.7, temperature increases by similar to 1.8, and the plasma flow velocity increases by similar to 3.8 across the shocks. The average upstream theta(Bn) is similar to 76 degrees, while the downstream angle is similar to 50 degrees. The shocks have an average M(An) similar to 0.87 along the normal direction, and an upstream beta(e) similar to 0.04. In the downstream plasma sheet region, the dominant plasma flow associated with the shocks is in the tailward direction with an average speed similar to 585 km/s. Only a few cases of Earthward downstream plasma flow have been detected. The slow shocks have thicknesses, on average, of similar to 5380 km (about 7 ion inertial lengths) and an average tilt angle of similar to +/-22.4 degrees between the shock normal and z axis. Using the Petschek slow shock model, the average location of the neutral lines is located in a range of +/-40 R(E) from observation sites. About half the slow mode shock events are detected during southward IMF intervals and half during northward intervals. There is a weak substorm dependence of slow mode shocks and plasmoids, a dependence which is most obvious when B-z > +2 nT and B-z < -2 nT intervals are intercompared. We see a substorm dependence for plasma sheet/lobe crossings which suggests that the deep tail become more dynamic during substorm intervals. We have also sought the existence of large wave trains downstream of slow shocks that have been theoretically predicted by Coroniti [1971] and simulation studies. No such wave trains were observed throughout the two ISEE 3 passes of the distant tail. However, we do detect some medium amplitude transverse waves in the shock ramp regions. The waves have frequencies and polarizations similar to the plasma sheet boundary layer waves reported by Tsurutani et al. [1985]. The waves present in the shock ramp are also right-hand ion cyclotron waves in the plasma frame. We believe that these waves are generated by the ion beams flowing away from the magnetic merging regions. C1 LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP Ho, CM (reprint author), CALTECH,JET PROP LAB,MS 169-506,PASADENA,CA 91109, USA. NR 31 TC 12 Z9 12 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1996 VL 101 IS A7 BP 15277 EP 15286 DI 10.1029/96JA00545 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV415 UT WOS:A1996UV41500006 ER PT J AU Fok, MC Moore, TE Greenspan, ME AF Fok, MC Moore, TE Greenspan, ME TI Ring current development during storm main phase SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EQUATORIAL MAGNETOSPHERE; GEOMAGNETIC STORM; MODEL; IONS; SUBSTORM; PLASMAPAUSE; SIMULATION; CONVECTION; TRANSPORT; DYNAMICS AB The development of the ring current ions in the inner magnetosphere during the main phase of a magnetic storm is studied. The temporal and spatial evolution of the ion phase space densities in a dipole field are calculated using a three dimensional ring current model, considering charge exchange and Coulomb losses along drift paths. The simulation starts with a quiet time distribution. The model is tested by comparing calculated ion fluxes with Active Magnetospheric Particle Tracer Explorers/CCE measurement during the storm main phase on May 2, 1986. Most of the calculated omnidirectional fluxes are in good agreement with the data except on the dayside inner edge (L < 2.5) of the ring current, where the ion fluxes are underestimated. The model also reproduces the measured pitch angle distributions of ions with energies below 10 keV. At higher energy, an additional diffusion in pitch angle is necessary in order to fit the data. The role of the induced electric field an the ring current dynamics is also examined by simulating a series of substorm activities represented by stretching and collapsing the magnetic field lines. In response to the impulsively changing fields, the calculated ion energy content fluctuates about a mean value that grows steadily with the enhanced quiescent field. C1 UNIV MARYLAND,DEPT PHYS,COLLEGE PK,MD 20742. RP Fok, MC (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. RI Moore, Thomas/D-4675-2012; Fok, Mei-Ching/D-1626-2012 OI Moore, Thomas/0000-0002-3150-1137; NR 41 TC 124 Z9 124 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1996 VL 101 IS A7 BP 15311 EP 15322 DI 10.1029/96JA01274 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV415 UT WOS:A1996UV41500009 ER PT J AU Birn, J Hesse, M AF Birn, J Hesse, M TI Details of current disruption and diversion in simulations of magnetotail dynamics SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID TAIL CURRENT DISRUPTION; FIELD-ALIGNED CURRENTS; NEAR-EARTH MAGNETOTAIL; SUBSTORM CURRENT WEDGE; CURRENT SHEET; MAGNETOSPHERIC SUBSTORMS; GROWTH-PHASE; GEOMAGNETIC-ACTIVITY; EXPANSION; ONSET AB Properties of current disruption and diversion are investigated on the basis of resistive MHD simulations which include the inner tail region with the transition toward a dipole field and the dynamic formation of a thin current sheet in the inner tail. As in earlier simulations, magnetotail instability leads to reconnection and plasmoid formation and ejection, accompanied by features of the substorm current wedge. In contrast to earlier simulations of the breakup of a thick current sheet, the presence of the thin current sheet leads to a much faster evolution on the timescale of few minutes and to larger electric fields(up to 20 mV/m), concentrated mostly in the dipolarizing region earthward of the reconnection site. The fast growth is relatively insensitive to the resistivity model used. The current ''disruption'' is largely a consequence of an expansion of the near-Earth current sheet, associated with the dipolarization. It starts well earthward of the reconnection site in association with a pileup of magnetic flux and propagates tailward. Field-aligned currents of region 1 type (toward the Earth on the dawn-side and away on the duskside) at the near-Earth boundary are found to increase both during the driven phase of the thin current sheet formation and during the energy release and current disruption phase. They result from a diversion of perpendicular into parallel currents, which is associated with a gradient of the magnetic flux tube volume directed away from midnight at the flank edges of the dipolarization region. Locally, the current diversion takes place earthward of the reconnection site, predominantly in shear layers above and below the neutral sheet rather than close to the neutral sheet. The peaks of the field-aligned current densities associated with the substorm wedge do not follow field lines very closely, because of the presence of strong perpendicular currents, so that care must be taken in using these features for a mapping between the Earth and the equatorial plane. C1 NASA,GODDARD SPACE FLIGHT CTR,ELECTRODYNAM BRANCH,GREENBELT,MD 20771. RP Birn, J (reprint author), LOS ALAMOS NATL LAB,SPACE & ATMOSPHER SCI GRP,MS D466,LOS ALAMOS,NM 87545, USA. RI Hesse, Michael/D-2031-2012 NR 52 TC 153 Z9 156 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1996 VL 101 IS A7 BP 15345 EP 15358 DI 10.1029/96JA00887 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV415 UT WOS:A1996UV41500012 ER PT J AU Burlaga, LF Ness, NF Belcher, JW Whang, YC AF Burlaga, LF Ness, NF Belcher, JW Whang, YC TI Pickup protons and pressure-balanced structures from 39 to 43 AU: Voyager 2 observations during 1993 and 1994 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; INTERSTELLAR HYDROGEN; NEUTRAL HYDROGEN; IONS; ELECTRONS AB The pressure of interstellar pickup protons in the distant heliosphere can be determined by analyzing pressure-balanced structures, observed on a scale of a few hundredths of an AU. This paper extends the earlier work of L. F. Burlaga et al. (Journal of Geophysical Research, 99, 21,511, 1994) by analyzing pressure-balanced structures observed by Voyager 2 from 39.3 to 40.6 AU in 1993 and from 42.6 to 43.2 AU during 1994. The pickup proton temperature is high in the region of the distant heliosphere that we considered: (5.4 +/- 0.1) x 10(6) K at 39-41 AU and (6.0 +/- 0.4) x 10(6) K at approximate to 43 AU. The density of the pickup protons is (1.6 +/- 0.3) x 10(-4) cm(-3) at 39-41 AU and (1.2 +/- 0.2) x 10(-4) cm(-3) at approximate to 43 AU. The ratio of the pickup proton density to the solar wind proton density (N-i/N) is small, only 0.03 +/- 0.01 during both 1993 and 1994. Nevertheless, the pickup proton pressures are relatively high because of their high temperatures. The pickup at 43 AU. There is a possible decrease in Pi with increasing distance from the Sun. The pickup proton pressure is an order of magnitude greater than the solar wind proton pressure: P-i/P-swp = 10 +/- 2 at 39-41 AU and 8 +/- 2 at 43 AU. Our results support the hypothesis of Burlaga et al. that the pickup proton pressure is more important than the solar wind thermal pressure in the dynamics of the distant heliosphere. The ratio of the pickup ion pressure to the magnetic pressure is P-i/(B-2/8 pi) = 1.7 +/- 0.3 at 39-41 AU and 1.7 +/- 0.72 at approximate to 43 AU. These results are compared with a model. C1 MIT,DEPT PHYS,CAMBRIDGE,MA 02139. UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. CATHOLIC UNIV AMER,WASHINGTON,DC 20064. MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. RP Burlaga, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 46 TC 32 Z9 32 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1996 VL 101 IS A7 BP 15523 EP 15532 DI 10.1029/96JA01076 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV415 UT WOS:A1996UV41500028 ER PT J AU Cliver, EW Cane, HV AF Cliver, EW Cane, HV TI The angular extents of solar/interplanetary disturbances and modulation of galactic cosmic rays SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTIONS; FORBUSH-TYPE DECREASES; INTERPLANETARY SHOCKS; OUTER HELIOSPHERE; PROTON EVENTS; PARTICLE-ACCELERATION; TRANSIENT DECREASES; SOLAR-WIND; PROPAGATION; EVOLUTION AB From comparisons of solar activity with galactic cosmic ray (GCR) modulation events at 1 AU and in the outer heliosphere, we argue against the suggestion that individual solar eruptions can give rise to major cosmic ray modulation events that span the heliosphere. For the inner heliosphere, we use a sample, covering a similar to 30-year period, of eruptive flares and confidently associated interplanetary shocks to show that the following three parameters, determined at 1 AU, all decrease with increasing longitudinal distance from the flare: probability of detecting a shock, shock transit speed, and magnitude of any associated Forbush decrease (FD). In addition, we associate each of the 18 large (greater than or equal to 10%) FDs observed at Earth from 1958 to 1991 with one or more eruptive flares located near solar central meridian (E47 - W31). For each of the six heliosphere-wide modulation events that have been associated thus far by other investigators with individual flares we are able to identify multiple powerful flares, with one or more of these eruptive events generally occurring close in ecliptic longitude to each affected spacecraft. Supporting evidence for the limited longitudinal extent of major interplanetary effects from single eruptions is provided by a remarkable outer heliosphere event in late 1989. A large shock (Delta V similar to 200 km/s) and Forbushlike decrease (18%) at Pioneer 10 at similar to 50 AU was not preceded by a commensurate disturbance at Voyager 1/Voyager 2/Pioneer 11 located at similar to 30-40 AU on the opposite side of the heliosphere. We conclude that widespread modulation events in the outer heliosphere result from systems of solar/interplanetary disturbances that, only in aggregate, encompass 360 degrees of ecliptic longitude, rather than from azimuthally symmetric shocks associated with single eruptive flares. We point out that the documented preference for coronal mass ejections to occur at low and middle solar latitudes will naturally form the wedge-shaped barrier proposed by Van Alien and Mihalov to account for the ''inside-out'' pattern of recovery of individual modulation events observed at progressively greater distances in the heliosphere. C1 UNIV TASMANIA, DEPT PHYS, HOBART, TAS 7001, AUSTRALIA. NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RP Cliver, EW (reprint author), PHILLIPS LAB, GEOPHYS DIRECTORATE GPSG, BEDFORD, MA 01731 USA. NR 84 TC 19 Z9 19 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 JUL 1 PY 1996 VL 101 IS A7 BP 15533 EP 15546 DI 10.1029/96JA00492 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV415 UT WOS:A1996UV41500029 ER PT J AU Stark, BA AF Stark, BA TI Wave resonances and induced flow due to nonlinear Alfven waves in a stratified atmosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR CORONAL HOLES; ISOTHERMAL ATMOSPHERE; MAGNETIC-FIELD; WIND; PROPAGATION AB This paper presents the results of a self-consistent, nonlinear, time-dependent, magnetohydrodynamic numerical code developed to investigate Alfven wave behavior in a smoothly stratified, isothermal, plane-parallel atmosphere with physical parameters approximating solar coronal holes. Emphasis is given to studies of resonant wave behavior and the origin of flow induced by both freely propagating and partially reflected monochromatic Alfven waves. The onset and subsequent development of this induced flow is calculated directly in both the linear and nonlinear regimes. The results of these investigations show that a resonance behavior exists, primarily because of continuous partial reflection experienced by the Alfven wave as it propagates through the atmosphere into a region where the wavelength approaches the scale height of the medium. Waves having periods corresponding to resonant peaks exert considerably more force on the medium than off-peak period waves, resulting in enhanced flow. For the segment of atmosphere considered, the more reflection experienced by the wave, the greater the enhanced flow. If only off-peak periods are considered, the relationship between the wave period and induced longitudinal velocity shows that short-period WKB waves push more on the medium than longer, non-WKB waves. However, the increase in flow because of resonance effects at longer wave periods is much greater in magnitude. This enhanced flow at resonant periods could contribute to the observationally required acceleration of the solar wind originating from coronal holes. The resulting wave energy transferred to the longitudinal mode may also provide a source of localized heating via longitudinal wave steepening and subsequent shock dissipation. RP Stark, BA (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, CODE ES82, HUNTSVILLE, AL 35812 USA. NR 35 TC 3 Z9 3 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1996 VL 101 IS A7 BP 15615 EP 15627 DI 10.1029/96JA00610 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV415 UT WOS:A1996UV41500036 ER PT J AU Krasnopolsky, VA Gladstone, GR AF Krasnopolsky, VA Gladstone, GR TI Helium on Mars: EUVE and PHOBOS data and implications for Mars' evolution SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID OXYGEN ION PRECIPITATION; MARTIAN ATMOSPHERE; SPATIAL DISTRIBUTIONS; ENERGY DEPOSITION; CONSEQUENCES; IMPACT; VENUS AB The EUVAC model of the solar EUV flux [Richards et al., 1994] and a recent analysis of terrestrial airglow at the He 584-Angstrom line by Bush and Chakrabarti [1995] imply an intensity in the center of the solar 584-Angstrom line which is lower by a factor of 1.8 than that estimated from the model of Tobiska [1991] and used in an earlier analysis of an EWE observation of the He 584-Angstrom airglow on Mars [Krasnopolsky er al., 1994]. Two different methods used to select signal from noise in the EUVE observation give Martian effective disk average airglow intensities of 44 and 70 R. To reproduce these intensities with the new solar flux, the helium mixing ratio in the lower atmosphere is required to be 4 +/- 2 ppm, The main escape process from the Martian atmosphere for helium is ionization above the ionopause followed by sweeping out by the solar wind. Our new result for the total escape rate is larger by a factor of 2.8 than the previous EUVE-derived value and is equal to (7.2 +/- 3.6) x 10(23) s(-1). This escape rate agrees fairly well with the (1.2 +/- 0.6) x 10(24) s(-1) value determined from Phobos 2 measurements by Barabash et al. [1995], taking into account the difference in solar activity. Helium is a minor component of the Martian exosphere reaching a fractional abundance of a few percent at some heights. Our models for the formation of He-4 and Ar-40 by radioactive decay of U, Th, and K and their outgassing from Mars' interior confirm the low degassing from Mars' interior and require a helium outgassing rate which is smaller by a factor 2-4 than the loss rate. The difference may be due to uncertainties of both values, to a possible enhanced outgassing during the last 5 x 10(4) years, to a higher outgassing coefficient of helium than that of argon, and to the contribution of solar wind a particles to the production of helium. Our models show that loss of Ar-40 by impact erosion and sputtering was substantial and constituted 75% of the current atmospheric abundance. C1 SW RES INST,SAN ANTONIO,TX 78228. RP Krasnopolsky, VA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Krasnopolsky, Vladimir/L-5085-2013 NR 29 TC 58 Z9 58 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1996 VL 101 IS A7 BP 15765 EP 15772 DI 10.1029/96JA01080 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UV415 UT WOS:A1996UV41500049 ER PT J AU Maghami, PG Giesy, DP AF Maghami, PG Giesy, DP TI Efficient computation of closed-loop frequency response for large-order flexible systems SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID LINEAR ALGEBRA SUBPROGRAMS; MODEL IMPLEMENTATION; TEST PROGRAMS; EXTENDED SET AB An efficient and robust computational scheme is given for the calculation of the frequency response function of a large-order, flexible system implemented with a linear, time-invariant control system. Advantage is taken of the highly structured sparsity of the system matrix of the plant based on a model of the structure using normal mode coordinates. The computational time per frequency point of the new computational scheme is a linear function of system size, a significant improvement over traditional, full-matrix techniques whose computational times per frequency point range from quadratic to cubic functions of system size. This permits the practical frequency-domain analysis of systems of much larger order than by traditional, full-matrix techniques. Formulations are given for both open- and closed-loop systems. Numerical examples are presented showing the advantages of tile present formulation over traditional approaches, both in speed and in accuracy. Using a model with 703 structural modes, a speed-up of almost two orders of magnitude was observed, while accuracy improved by up to 5 decimal places. C1 LOCKHEED MARTIN ENGN & SCI,HAMPTON,VA 23666. RP Maghami, PG (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 17 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 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1996 VL 19 IS 4 BP 780 EP 786 DI 10.2514/3.21699 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA UV695 UT WOS:A1996UV69500005 ER PT J AU Zelenka, RE Clark, RF Zirkler, A Saari, R Branigan, RG AF Zelenka, RE Clark, RF Zirkler, A Saari, R Branigan, RG TI Development and flight test of terrain-referenced guidance with ladar forward sensor SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Military aircraft regularly conduct missions that include low-altitude, near-terrain flight to increase covertness and payload effectiveness. Civilian aircraft operate in this regime during airborne fire fighting, police surveillance, search and rescue, and helicopter emergency medical service applications. Several fixed-wing aircraft now employ terrain elevation maps and forward-pointed radars to achieve automated terrain following or terrain avoidance flight. Similar systems specialized to helicopters and their flight regime have not received as much attention. A helicopter guidance system relying on digitized terrain elevation maps has been developed that employs airborne. navigation, mission requirements, aircraft performance limits, and radar altimeter returns to generate a valley-seeking, low-altitude trajectory between waypoints. The guidance trajectory is symbolically presented to the pilot on a helmet-mounted display. In this work, a wide field of view laser radar forward sensor has been incorporated into this guidance system to expand the system's operational flight envelope and to assist the pilot in obstacle detection and avoidance. The development and flight test results of this guidance system are presented. Missions to 75 ft altitude at 80 kn in the presence of unmapped natural and man-made obstacles were achieved while the pilot maintained situational awareness and tracking of the guidance trajectory. C1 USA COMMAND,CONTROL & SYST INTEGRAT DIRECTORATE,SYST DEV BRANCH,FT MONMOUTH,NJ 07703. UNIXPROS,EATONTOWN,NJ 07724. USA,NIGHT VIS & ELECT SENSOR SYST DIRECTORATE,AIRBORNE APPLICAT BRANCH,FT BELVOIR,VA 22060. RP Zelenka, RE (reprint author), NASA,AMES RES CTR,FLIGHT DECK BRANCH,M-S 262-3,MOFFETT FIELD,CA 94035, USA. NR 10 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 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1996 VL 19 IS 4 BP 823 EP 828 DI 10.2514/3.21705 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA UV695 UT WOS:A1996UV69500011 ER PT J AU Huang, JK Hsiao, MH Cox, DE AF Huang, JK Hsiao, MH Cox, DE TI Indirect identification of linear stochastic systems with known feedback dynamics SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB An algorithm is presented for identifying a state-space model of linear stochastic systems operating under known feedback controller. In this algorithm, only the reference input and output of closed-loop data are required. No feedback signal needs to be recorded. The overall closed-loop system dynamics is first identified. Then a recursive formulation is derived to compute the open loop plant dynamics from the identified closed-loop system dynamics and known feedback controller dynamics. The controller can he a dynamic or constant-gain full-state feedback controller. Numerical simulations and test data of a highly unstable large-gap magnetic suspension system are presented to demonstrate the feasibility of this indirect identification method. C1 TAIPEI INST TECHNOL,DEPT MECH ENGN,TAIPEI,TAIWAN. NASA,LANGLEY RES CTR,GUIDANCE & CONTROL BRANCH,FLIGHT DYNAM & CONTROL DIV,HAMPTON,VA 23681. RP Huang, JK (reprint author), OLD DOMINION UNIV,DEPT MECH ENGN,NORFOLK,VA 23529, USA. NR 22 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1996 VL 19 IS 4 BP 836 EP 841 DI 10.2514/3.21707 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA UV695 UT WOS:A1996UV69500013 ER PT J AU Roithmayr, CM Hu, AR Chipman, R AF Roithmayr, CM Hu, AR Chipman, R TI Motion of a spacecraft with magnetic damper SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article C1 DYNACS ENGN CO,PALM HARBOR,FL 34684. GRUMMAN CORP,DIV SPACE STN,INTEGRATED PERFORMANCE ANAL BRANCH,RESTON,VA 22090. RP Roithmayr, CM (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,VEHICLE DYNAM SECT,HOUSTON,TX 77058, USA. NR 15 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 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1996 VL 19 IS 4 BP 980 EP 982 DI 10.2514/3.21732 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA UV695 UT WOS:A1996UV69500039 ER PT J AU Jalihal, P Utku, S Wada, BK AF Jalihal, P Utku, S Wada, BK TI Optimal location of redundants for prestressing adaptive trusses SO JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES LA English DT Article AB This paper describes the location selection of minimum number of actuator mounted redundant bars for complete prestressing of a determinate truss. Two computationally simple algorithms are presented to obtain the optimal locations of the redundants. The optimal bar pre stresses are then obtained by using the least squares solution for the redundant bar forces. knowing the desired list of bar pre-stresses. The paper then proposes the use of a positive scale parameter. to prevent local buckling/rupture of individual bars of the resulting indeterminate truss and its global buckling. The procedure is illustrated on a simple two-dimensional truss. C1 DUKE UNIV,DURHAM,NC 27708. JET PROP LAB,PASADENA,CA 91109. RP Jalihal, P (reprint author), INDIAN INST TECHNOL,D1-118 BONN AVE,MADRAS 600036,TAMIL NADU,INDIA. NR 12 TC 0 Z9 0 U1 1 U2 3 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 1045-389X J9 J INTEL MAT SYST STR JI J. Intell. Mater. Syst. Struct. PD JUL PY 1996 VL 7 IS 4 BP 420 EP 426 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA VE110 UT WOS:A1996VE11000006 ER PT J AU Carton, JA Cao, XH Giese, BS daSilva, AM AF Carton, JA Cao, XH Giese, BS daSilva, AM TI Decadal and interannual SST variability in the tropical Atlantic Ocean SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID SEA-SURFACE TEMPERATURE; EQUATORIAL ATLANTIC; HEAT-FLUX; EL-NINO; PACIFIC-OCEAN; CIRCULATION; ANOMALIES; RAINFALL; MODEL; SIMULATION AB The mechanisms regulating interannual and decadal variations of sea surface temperature (SST) in the tropical Atlantic are examined. Observed variations of sea surface temperature are typically in the range of 0.3 degrees-0.5 degrees C and are linked to fluctuations in rainfall on both the African and South American continents. The authors use a numerical model to simulate the observed time series of sea surface temperature for the period 1960-1989. Based on the results, experiments are conducted to determine the relative importance of heat flux and momentum forcing. Two dominant timescales for variability of SST are identified: a decadal timescale that is controlled by latent heat flux anomalies and is primarily responsible for SST anomalies off the equator and an equatorial mode with a timescale of 2-5 years that is dominated by dynamical processes. The interhemispheric gradient of anomalous SST (the SST dipole) is primarily linked to the former process and thus results from the gradual strengthening and weakening of the trade wind system of the two hemispheres. C1 TEXAS A&M UNIV,DEPT OCEANOG,COLLEGE STN,TX 77843. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP Carton, JA (reprint author), UNIV MARYLAND,DEPT METEOROL,COLLEGE PK,MD 20742, USA. RI carton, james/C-4807-2009; da Silva, Arlindo/D-6301-2012 OI carton, james/0000-0003-0598-5198; da Silva, Arlindo/0000-0002-3381-4030 NR 30 TC 180 Z9 185 U1 3 U2 11 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD JUL PY 1996 VL 26 IS 7 BP 1165 EP 1175 DI 10.1175/1520-0485(1996)026<1165:DAISVI>2.0.CO;2 PG 11 WC Oceanography SC Oceanography GA VB317 UT WOS:A1996VB31700004 ER PT J AU Glazman, RE AF Glazman, RE TI Spectra of baroclinic inertia-gravity wave turbulence SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID MESOSCALE VARIABILITY; EQUILIBRIUM RANGE; SEASAT ALTIMETER; ATLANTIC; OCEAN AB Baroclinic inertia-gravity (IG) waves form a persistent background of thermocline depth and sea surface height oscillations. They also contribute to the kinetic energy of horizontal motions in the subsurface layer. Measured by the ratio of water particle velocity to wave phase speed, the wave nonlinearity may be rather high. Given a continuous supply of energy from external sources, nonlinear wave-wave interactions among IG waves would result in inertial cascades of energy, momentum, and wave action. Based on a recently developed theory of wave turbulence in scale-dependent systems, these cascades are investigated and IG wave spectra are derived for an arbitrary degree of wave nonlinearity. Comparisons with satellite-altimetry-based spectra of surface height variations and with energy spectra of horizontal velocity fluctuations show good agreement. The well-known spectral peak at the inertial frequency is thus explained as a result of the inverse cascade. Finally, we discuss a possibility of inferring the internal Rossby radius of deformation and other dynamical properties of the upper thermocline from the spectra of SSH variations based on altimeter measurements. RP Glazman, RE (reprint author), CALTECH,JET PROP LAB,MS 300-323,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 28 TC 5 Z9 5 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD JUL PY 1996 VL 26 IS 7 BP 1256 EP 1265 DI 10.1175/1520-0485(1996)026<1256:SOBIGW>2.0.CO;2 PG 10 WC Oceanography SC Oceanography GA VB317 UT WOS:A1996VB31700009 ER PT J AU Ivins, M Cole, J AF Ivins, M Cole, J TI Proprioception in space: A video of the sense of arm and leg position in microgravity SO JOURNAL OF PHYSIOLOGY-LONDON LA English DT Article; Proceedings Paper CT Scientific Meeting of the Physiological-Society CY APR 16-18, 1996 CL UNIV COLL LONDON, LONDON, ENGLAND SP Physiol Soc HO UNIV COLL LONDON C1 SOUTHAMPTON GEN HOSP,SOUTHAMPTON SO16 6YD,HANTS,ENGLAND. RP Ivins, M (reprint author), NASA,HOUSTON,TX 77058, USA. NR 3 TC 1 Z9 1 U1 1 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-3751 J9 J PHYSIOL-LONDON JI J. Physiol.-London PD JUL PY 1996 VL 494P BP P5 EP P5 PG 1 WC Neurosciences; Physiology SC Neurosciences & Neurology; Physiology GA VA341 UT WOS:A1996VA34100006 ER PT J AU Mackowiak, CL Wheeler, RM AF Mackowiak, CL Wheeler, RM TI Growth and stomatal behavior of hydroponically cultured potato (Solanum tuberosum L) at elevated and super-elevated CO2 SO JOURNAL OF PLANT PHYSIOLOGY LA English DT Article DE CELSS; carbon dioxide; Solanum tuberosum; stomatal conductance; water use efficiency ID LIFE SUPPORT SYSTEMS; INDIVIDUAL TUBERS; PHOTOSYNTHATE; PHOTOPERIODS; ALLOCATION; TEMPERATURE; EXCHANGE; SPACE AB Potato cultivars Denali and Norland were grown in a controlled environment under low irradiance and CO2 partial pressures of 50, 100, 500, and 1000 Pa. The highest CO2 partial pressures, 500 and 1000 Pa, reduced tuber yield when compared to 100 Pa CO2. Upper canopy stomatal conductance was greatest at the higher CO2 partial pressures (500 and 1000 Pa) for both cultivars, and conductance of Denali was consistently higher than Norland. Stomatal conductance tended to decline sooner with plant age at 50 and 100 Pa CO2 than at 500 and 1000 Pa. Water uptake was also greatest at the higher CO2 partial pressures, which resulted in lowest water-use efficiencies at 500 and 1000 Pa. These observations suggest that stomatal function under very high CO2 partial pressures (500-1000 Pa) does not follow known patterns observed at moderate partial pressures (50-100 Pa). Although there is little concern about CO2 partial pressures reaching extreme levels in the natural environment, this information should be useful for controlled environments or space life support systems (e.g. space vehicles or habitats), where CO2 partial pressures of 500-1000 Pa are common. C1 NASA,BIOL RES & LIFE SUPPORT,RMW,KENNEDY SPACE CTR,FL 32899. RP Mackowiak, CL (reprint author), DYNAMAC CORP,CLM,MAIL CODE DYN-3,KENNEDY SPACE CTR,FL 32899, USA. NR 31 TC 33 Z9 34 U1 0 U2 8 PU GUSTAV FISCHER VERLAG PI STUTTGART PA WOLLGRASWEG 49, D-70599 STUTTGART, GERMANY SN 0176-1617 J9 J PLANT PHYSIOL JI J. Plant Physiol. PD JUL PY 1996 VL 149 IS 1-2 BP 205 EP 210 PG 6 WC Plant Sciences SC Plant Sciences GA VD215 UT WOS:A1996VD21500034 ER PT J AU Sambamurthi, JK Alvarado, A Mathias, EC AF Sambamurthi, JK Alvarado, A Mathias, EC TI Correlation of slag expulsion with ballistic anomalies in shuttle solid rocket motors SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/ASME/SAE/ASEE 31st Joint Propulsion Conference and Exhibit CY JUL 10-12, 1995 CL SAN DIEGO, CA SP AIAA, ASME, SAE, ASEE AB During the Shuttle launches, the solid rocket motors (SRM) occasionally experience pressure perturbations (8-13 psi) between 65-75 s into the motor burn time. The magnitudes of these perturbations are very small in comparison with the operating motor chamber pressure, which is over 600 psi during this time frame, These SRM pressure perturbations are believed to be caused primarily by the expulsion of slag (aluminum oxide), Two SRM static tests, TEM-11 and FSM-4, were instrumented extensively for the study of the phenomena associated with pressure perturbations, The test instrumentation used included nonintrusive optical and infrared diagnostics of the plume, such as high-speed photography, radiometers, and thermal image cameras, Results from all of these nonintrusive observations provide substantial circumstantial evidence to support the scenario that the pressure perturbation event in the Shuttle SRM is caused primarily by the expulsion of molten slag, In the static motor tests, the slag was also expelled preferentially near the bottom of the nestle because of slag accumulation st the bottom of the aft end of the horizontally oriented motor. C1 THIKOL CORP,BRIGHAM CITY,UT 84302. RP Sambamurthi, JK (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 13 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 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1996 VL 12 IS 4 BP 625 EP 631 DI 10.2514/3.24082 PG 7 WC Engineering, Aerospace SC Engineering GA UX580 UT WOS:A1996UX58000001 ER PT J AU Wilson, J Paxson, DE AF Wilson, J Paxson, DE TI Wave rotor optimization for gas turbine engine topping cycles SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Use of a wave rotor as a topping cycle for a gas turbine engine can improve specific power and reduce specific fuel consumption. Maximum improvement requires the wave rotor to be optimized for best performance at the mass flow of the engine. The optimization is a tradeoff between losses because of friction and passage opening time and rotational effects. An experimentally validated, one dimensional computational fluid dynamics code, which includes these effects, has been used to calculate wave rotor performance and find the optimum configuration. The technique is described, and results given, for wave rotors sized for engines with sea level mass hows of 4, 26, and 400 Ib/s. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Wilson, J (reprint author), NYMA INC,2001 AEROSP PKWY,BROOKPARK,OH 44142, USA. NR 23 TC 18 Z9 20 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1996 VL 12 IS 4 BP 778 EP 785 DI 10.2514/3.24101 PG 8 WC Engineering, Aerospace SC Engineering GA UX580 UT WOS:A1996UX58000020 ER PT J AU Steinetz, BM Hendricks, RC AF Steinetz, BM Hendricks, RC TI Engine seal technology requirements to meet NASA's advanced subsonic technology program goals SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Cycle studies have shown the benefits of increasing engine pressure ratios and cycle temperatures to decrease engine weight and improve the performance of commercial turbine engines. NASA and the industry have defined technology requirements of advanced engines and engine technology to meet the goals of NASA's Advanced Subsonic Technology (AST) initiative, A number of new technologies are being developed that will allow next-generation engines to operate at higher pressures and temperatures to meet engine efficiency and performance goals, Improving seal performance, reducing leakage and increasing service life while operating under more demanding conditions, will play an important role in meeting overall program goals, This article provides an overview of the AST program, discusses the motivation for advanced seal development, and highlights seal technology requirements to meet future engine performance goals. C1 NASA,LEWIS RES CTR,SPACE RES DIV,CLEVELAND,OH 44135. RP Steinetz, BM (reprint author), NASA,LEWIS RES CTR,STRUCT DYNAM BRANCH,CLEVELAND,OH 44135, USA. NR 27 TC 2 Z9 2 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1996 VL 12 IS 4 BP 786 EP 793 DI 10.2514/3.24102 PG 8 WC Engineering, Aerospace SC Engineering GA UX580 UT WOS:A1996UX58000021 ER PT J AU Stallard, BW Hooper, EB Power, JL AF Stallard, BW Hooper, EB Power, JL TI Whistler-driven, electron-cyclotron-resonance-heated thruster: Experimental status SO JOURNAL OF PROPULSION AND POWER LA English DT Article C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP Stallard, BW (reprint author), LAWRENCE LIVERMORE NATL LAB, ENERGY DIRECTORATE, LIVERMORE, CA 94551 USA. NR 11 TC 3 Z9 3 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1996 VL 12 IS 4 BP 814 EP 816 DI 10.2514/3.24108 PG 3 WC Engineering, Aerospace SC Engineering GA UX580 UT WOS:A1996UX58000027 ER PT J AU Bertin, JJ Campbell, CH AF Bertin, JJ Campbell, CH TI Recent aerothermodynamic flight measurements during shuttle orbiter re-entry SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB All four Space Shuttle Orbiters, which are currently operational, have limited instrumentation packages that provide information about the aerothermodynamic environment. Heat transfer rates have been determined from the measured temperature histories using a simple technique. The experimental rates thus determined have been compared with previous flight data and with existing computations. The comparisons were used to evaluate the data in general, to study viscous-inviscid interactions such as those due to body-flap deflections, and to evaluate possible flight anomalies. C1 LOCKHEED MARTIN ENGN & SCI,HOUSTON,TX 77258. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP Bertin, JJ (reprint author), USAF ACAD,DEPT AERONAUT,COLORADO SPRINGS,CO 80840, USA. NR 16 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 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1996 VL 33 IS 4 BP 457 EP 462 DI 10.2514/3.26785 PG 6 WC Engineering, Aerospace SC Engineering GA VB402 UT WOS:A1996VB40200001 ER PT J AU Weilmuenster, KJ Gnoffo, PA Greene, FA Riley, CJ Hamilton, HH Alter, SJ AF Weilmuenster, KJ Gnoffo, PA Greene, FA Riley, CJ Hamilton, HH Alter, SJ TI Hypersonic aerodynamic characteristics of a proposed single-stage-to-orbit vehicle SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SCHEMES AB The hypersonic aerodynamic characteristics of a candidate winged-body single-stage-to-orbit vehicle that features wing/tip-fin controllers and elevon/body/flap control surfaces are predicted at points along a nominal trajectory for Mach numbers from 5 to 27 and angles of attack from 19 to 32 deg. Predictions are derived from surface properties based on flow solvers for inviscid and viscous, laminar flows for a perfect gas or reacting (equilibrium or nonequilibrium) gas. At a Mach number of 22, the lateral aerodynamic characteristics of the vehicle are determined for an inviscid analysis at sideslip angles of 2 and 4 deg and 32-deg angle of attack; a viscous analysis demonstrated the effect of gas chemistry modeling on surface pressure and was used to determine the incremental aerodynamics for control-surface deflections. The results show that the longitudinal pitch characteristics of the baseline configuration, i.e., zero-control surface deflections, are significantly altered by real-gas chemistry at angles of attack greater than 30 deg and Mach numbers greater than 9, and that aerodynamics derived from inviscid solutions are of sufficient accuracy for preliminary analysis. Also, it is shown that a Mach number of 22, the choice of gas chemistry model has a large impact on surface pressure levels in highly localized regions on the vehicle and that the vehicle ran be trimmed at control-surface deflections less than 11 deg. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP Weilmuenster, KJ (reprint author), NASA,LANGLEY RES CTR,AEROTHERMODYNAM BRANCH,RES TECHNOL GRP,HAMPTON,VA 23665, USA. NR 15 TC 2 Z9 2 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1996 VL 33 IS 4 BP 463 EP 469 DI 10.2514/3.26786 PG 7 WC Engineering, Aerospace SC Engineering GA VB402 UT WOS:A1996VB40200002 ER PT J AU Park, C Menees, GP Bowles, JV Lawrence, SL Davies, CB AF Park, C Menees, GP Bowles, JV Lawrence, SL Davies, CB TI Bent-biconic single-stage-to-orbit vehicle conceptual study SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A new design concept is proposed for an all-propulsive, vertical-takeoff/horizontal-landing, reus able single-stage-to-orbit space transportation system. The vehicle is to carry an unmanned payload of 11 tons to a 400-km orbit inclined at 51 deg. It is shaped in a bent-biconic geometry, has no wings but horizontal and vertical stabilizers, and relies on a para-wing for landing. Its tripropellant propulsion system uses both RP1-LOX and LH2-LOX. The vehicle is sized and the weights of its components are estimated using an existing methodology, The ascent and entry flight scenarios are calculated, and their features are compared with those of the existing reference winged-body design, The bent-biconic design is found to be competitive with the reference design in its performance, The new design is advantageous in that it can avoid aerodynamic instabilities at transonic speed range and is free from the problem of excessive heating at the wing leading edge as a result of shock/boundary-layer interactions, leading to a lighter liftoff weight, However, the viability of this new design is dependent on further development of para-wing technology. C1 NASA,AMES RES CTR,REACTING FLOW ENVIRONM BRANCH,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,SYST ANAL BRANCH,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,APPL COMPUTAT & AERODYNAM BRANCH,MOFFETT FIELD,CA 94035. STERLING SOFTWARE,SCI SYST DIV,MOFFETT FIELD,CA 94035. NR 12 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 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1996 VL 33 IS 4 BP 470 EP 475 DI 10.2514/3.26787 PG 6 WC Engineering, Aerospace SC Engineering GA VB402 UT WOS:A1996VB40200003 ER PT J AU Larson, CR Woodard, SE Tischner, L Tong, E Schmidt, M Cheng, J Fujii, E Ghofranian, S AF Larson, CR Woodard, SE Tischner, L Tong, E Schmidt, M Cheng, J Fujii, E Ghofranian, S TI Multipayload modeling for the upper atmosphere research satellite SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A multipayload spacecraft modeling approach that combines constituent subassemblies (plant and controllers) into a combined system (model synthesis) is presented. This technique was used to model the Upper Atmosphere Research Satellite. The simulation was developed to determine the amount of controls-structure interaction, and the satellite flight results verified simulation predictions during payload tracking and scan modes and solar-array sun-tracking modes, The simulation was developed using the Dynamics Analysis Design System program, The program was modified to include a multirate sampling capability, a robust analog delay element, a stepper-motor kinematic driver, and a modified flexible body formulation. The simulation includes the structural models of the satellite components, the dominant flexible modes, the vehicle attitude control system and orbit adjust capability, and all instrument elevation and azimuth control systems. The model includes the flexible modes below 16 Hz and the instrument control systems. This study presented simulation results using the synthesized modeling approach and the in-flight data to validate the approach C1 NASA,LANGLEY RES CTR,STUCT DYNAM BRANCH,HAMPTON,VA 23681. ROCKWELL INT CORP,TECH STAFF,DOWNEY,CA 90241. RP Larson, CR (reprint author), ROCKWELL INT CORP,VEHICLE & SYST ANAL,DOWNEY,CA 90241, USA. NR 15 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 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1996 VL 33 IS 4 BP 489 EP 493 DI 10.2514/3.26789 PG 5 WC Engineering, Aerospace SC Engineering GA VB402 UT WOS:A1996VB40200006 ER PT J AU Ojakangas, GW Anderson, BJ AnzMeador, PD AF Ojakangas, GW Anderson, BJ AnzMeador, PD TI Solid-rocket-motor contribution to large-particle orbital debris population SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID ACCUMULATION AB Observations of solid-rocket-motor static firings indicate that these motors contribute to the centimeter-sized orbital debris population when they are used as launch vehicles. An analytic solution for the orbital distribution of this ablative debris from on-orbit solid-rocket-motor firings is presented and applied to a data set containing a large fraction of such firings in Earth orbit during the 1980s. Assuming 400 ablative objects are released per burn, it is found for altitudes above about 500 km that their spatial density is negligible in comparison with predicted I-cm densities from other sources for the gear 1990, Ablative-debris densities exceed predictions for other sources below about 250 km, but these densities are small. In the planned altitude range for the International Space Station (about 400 km), our results suggest that ablative particles pose about 10% as great a hazard as debris from other sources. However, these results are preliminary and should be updated as more complete data become available regarding the number of particles emitted per firing and historical solid-rocket-motor launches. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ELECTROMAGNET & AEROSP ENVIRONM BRANCH,HUNTSVILLE,AL 35812. VIKING SCI & TECHNOL INC,HOUSTON,TX 77058. RP Ojakangas, GW (reprint author), UNIV MINNESOTA,DEPT GEOL,10 UNIV DR,DULUTH,MN 55812, USA. NR 8 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 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1996 VL 33 IS 4 BP 513 EP 518 DI 10.2514/3.26793 PG 6 WC Engineering, Aerospace SC Engineering GA VB402 UT WOS:A1996VB40200010 ER PT J AU Butterfield, AJ Woodard, SE AF Butterfield, AJ Woodard, SE TI Measured spacecraft instrument and structural interactions SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Evaluation of Eight data from the Upper Atmosphere Research Satellite shows that the solar-disk tracking subsystem within the Halogen Occultation Experiment responds to and completely accommodates cyclic disturbances from the spacecraft solar-array vibration and continuous scanning motions by the High-Resolution Doppler Imager instrument. A fine sun sensor within the Halogen Occultation Experiment senses the top egde of the solar disk as the primary tracking control input, Data streams from such sensing show a characteristic frequency, which is principally determined by the apparent solar motion. Power-spectral-density renderings of sun sensor data streams show the disturbing frequencies as sideband peaks around a central peak at the characteristic frequency. The sidebands are analogous to frequency modulation of a carrier frequency. A mathematical model developed for this analysis demonstrates the factors that influence the frequency-modulated measurements. Modeling analyses verified the frequency content and allowed estimates of local relative amplitudes of the principal disturbances imparted to the spacecraft. The model can predict mutual interactions between instruments as well as the influence of structural excitations upon instruments. This analysis offers a means toward evaluating potentials for adverse interactions in cases where a spacecraft carries closed-loop instruments that track fixed solar or stellar targets; such interactions can become crucial if tracking requirements have small margins of error. C1 NASA,LANGLEY RES CTR,STRUCT DIV,STRUCT DYNAM BRANCH,HAMPTON,VA 23681. RP Butterfield, AJ (reprint author), BIONET CORP,SUITE 1000,2 EATON ST,HAMPTON,VA 23669, USA. NR 7 TC 9 Z9 9 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1996 VL 33 IS 4 BP 556 EP 562 DI 10.2514/3.26799 PG 7 WC Engineering, Aerospace SC Engineering GA VB402 UT WOS:A1996VB40200016 ER PT J AU Tischler, MB Williams, JN Ham, JA AF Tischler, MB Williams, JN Ham, JA TI The new ADS-33 process: Cautions for implementation - Comment SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article C1 USA,AVIAT TECH TEST CTR,AIRWORTHINESS QUALIFICAT TEST DIRECTORATE,EDWARDS AFB,CA. USA,AVIAT RES DEV & ENGN CTR,AEROFLIGHTDYNAM DIRECTORATE,AMES RES CTR,WASHINGTON,DC 20310. NR 17 TC 0 Z9 0 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1996 VL 41 IS 3 BP 194 EP 195 PG 2 WC Engineering, Aerospace SC Engineering GA VA268 UT WOS:A1996VA26800002 ER PT J AU Wang, PKC Hadaegh, FY AF Wang, PKC Hadaegh, FY TI Coordination and control of multiple microspacecraft moving in formation SO JOURNAL OF THE ASTRONAUTICAL SCIENCES LA English DT Article ID AUTONOMOUS MOBILE ROBOTS; ATTITUDE-CONTROL PROBLEM; NAVIGATION STRATEGIES; INTERACTION DYNAMICS AB The problem of coordination and control of multiple microspacecraft (MS) moving in formation is considered. Here, each MS is modelled by a rigid body with fixed center of mass. First, various schemes for generating the desired formation patterns are discussed. Then, explicit control laws for formation-keeping and relative attitude alignment based on nearest neighbor-tracking are derived. The necessary data which must be communicated between the MS to achieve effective control are examined. The time-domain behavior of the feedback-controlled MS formation for typical low-Earth orbits is studied both analytically and via computer simulation. The paper concludes with a discussion of the implementation of the derived control laws, and the integration of the MS formation coordination and control system with a proposed inter-spacecraft communication/computing network. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP Wang, PKC (reprint author), UNIV CALIF LOS ANGELES,DEPT ELECT ENGN,LOS ANGELES,CA 90024, USA. NR 19 TC 210 Z9 221 U1 1 U2 14 PU AMER ASTRONAUTICAL SOC PI SPRINGFIELD PA 6352 ROLLING MILL PLACE SUITE 102, SPRINGFIELD, VA 22152 SN 0021-9142 J9 J ASTRONAUT SCI JI J. Astronaut. Sci. PD JUL-SEP PY 1996 VL 44 IS 3 BP 315 EP 355 PG 41 WC Engineering, Aerospace SC Engineering GA WG114 UT WOS:A1996WG11400003 ER PT J AU DelSole, T Farrell, BF AF DelSole, T Farrell, BF TI Quasi-linear equilibration of a thermally maintained, stochastically excited jet in a quasigeostrophic model SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID EDDY HEAT-FLUX; BAROCLINIC WAVES; PARAMETERIZATION; INSTABILITY; DYNAMICS; GROWTH AB A theory for quasigeostrophic turbulence in baroclinic jets is examined in which interaction between the mean flow and the perturbations is explicitly modeled by the nonnormal operator obtained by linearization about the mean flow, while the eddy-eddy interactions are parameterized by a combination of stochastic excitation and effective dissipation. The quasi-linear equilibrium is the stationary state in dynamical balance between the mean flow forcing and eddy forcing produced by the linear stochastic model. The turbulence model depends on two parameters that specify the magnitude of the effective dissipation and stochastic excitation. The quasi-linear model produces heat fluxes (upgradient), momentum fluxes, and mean zonal winds, which are remarkably consistent with those produced by the nonlinear model over a wide range of parameter values despite energy and enstrophy imbalances associated with the parameterization for eddy-eddy interactions. The quasi-linear equilibrium also appears consistent with most aspects of the energy cycle, with baroclinic adjustment (though the adjustment is accomplished in a fundamentally different manner), and with the negative correlation between transient eddy transport and other transports observed in the atmosphere. The model overestimates the equilibrium eddy kinetic energy in cases in which it achieves correct eddy fluxes and energy balance. Understanding the role of forcing orthogonal functions rationalizes this behavior and provides the basis for addressing the role of transient eddies in climate. C1 HARVARD UNIV, DEPT EARTH & PLANETARY SCI, CAMBRIDGE, MA 02138 USA. RP DelSole, T (reprint author), NASA, GODDARD SPACE FLIGHT CTR, DATA ASSIMILAT OFF, CODE 9103, GREENBELT, MD 20771 USA. NR 31 TC 33 Z9 33 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 EI 1520-0469 J9 J ATMOS SCI JI J. Atmos. Sci. PD JUL 1 PY 1996 VL 53 IS 13 BP 1781 EP 1797 DI 10.1175/1520-0469(1996)053<1781:TQLEOA>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UZ829 UT WOS:A1996UZ82900002 ER PT J AU Barela, PR Cornford, SL AF Barela, PR Cornford, SL TI A systematic approach to hardware qualification SO JOURNAL OF THE INSTITUTE OF ENVIRONMENTAL SCIENCES LA English DT Article DE hardware qualification; QFD; physics of failure; failure modes; defect detection; defect prevention; test effectiveness; risk management AB A systematic approach for the development of a hardware qualification approach is described. This approach stems from the need to address the ''Catch-22'' of not flying new technology because it has not flown. A physics of failure approach is used to identify failure modes, and the impact and likelihood of these failures on the mission requirements is plotted in a Requirements Matrix. These same failure modes are plotted against the effectiveness of the available preventions, analyses, control, and rests (PACTs) at screening for, or eliminating, these failure modes in a test effectiveness matrix. Matrix multiplication results in a ranked set of PACTs that can be sorted according to cost and redundancy with other PACTs. This and other information resulting from the process allows project managers to make more informed decisions regarding the cost and risk tradeoffs inherent in any qualification program. RP Barela, PR (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 INST ENVIRONMENTAL SCI PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 SN 1052-2883 J9 J INST ENVIRON SCI JI J. Inst. Environ. Sci. PD JUL-AUG PY 1996 VL 39 IS 4 BP 33 EP 39 PG 7 WC Engineering, Environmental; Environmental Sciences; Instruments & Instrumentation SC Engineering; Environmental Sciences & Ecology; Instruments & Instrumentation GA VE846 UT WOS:A1996VE84600004 ER PT J AU Boden, AF Redding, DC Hanisch, RJ Mo, J AF Boden, AF Redding, DC Hanisch, RJ Mo, J TI Massively parallel spatially variant maximum-likelihood restoration of hubble space telescope imagery SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article DE image restoration; spatially variant point-spread function; parallel processing; deconvolution AB We present results of concurrent maximum-likelihood restoration implementations with a spatially variant point-spread function (SV-PSF) on both synthetic and real data sets from the Hubble Space Telescope. We demonstrate that SV-PSF restoration exhibits superior performance compared with restoration with a spatially invariant point-spread function. We realize concurrency on a network of Unix workstations and on a SV-PSF model from sparse point-spread function reference information by means of bilinear interpolation. We then use the interpolative point-spread function model to implement several different SV-PSF restoration methods. These restoration methods are tested on a standard synthetic Hubble Space Telescope test case, and the results are compared on a computational effort-restoration performance basis. These methods are further applied to actual Hubble Space Telescope data, including an application that corrects for motion blur, and the results are presented. (C) 1996 Optical Society of America. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP Boden, AF (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 32 TC 23 Z9 25 U1 0 U2 5 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD JUL PY 1996 VL 13 IS 7 BP 1537 EP 1545 DI 10.1364/JOSAA.13.001537 PG 9 WC Optics SC Optics GA UU124 UT WOS:A1996UU12400029 ER PT J AU Sharma, SP Whiting, EE AF Sharma, SP Whiting, EE TI Modeling of nonequilibrium radiation phenomena: An assessment SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID EARTHS ATMOSPHERE AB The present understanding of shock-layer radiation in the low-density regime, as appropriate to hypersonic vehicles, is discussed. Calculated spectra using the NONEQ and GENRAD computer programs are compared with experimental spectra recorded at NASA Ames's electric arc driven shock-tube facility. The computations predict the intensity of the N-2(+)(1(-)) system very well, but overpredict the intensities of various atomic O and N transitions and underpredict the intensities of the N-2(2(+)) band system. To compute the correct electronic populations, it appears that the quasi steady-state formulation must be expanded to include more individual electronic states. However, this may cause some computational difficulties and will require excitation rate data for many states, which are not well known. C1 THERMOSCI INST,MOFFETT FIELD,CA 94035. RP Sharma, SP (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 30 TC 6 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1996 VL 10 IS 3 BP 385 EP 396 DI 10.2514/3.802 PG 12 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA UY335 UT WOS:A1996UY33500001 ER PT J AU Scott, CD Lefebvre, M AF Scott, CD Lefebvre, M TI Determining electron temperature and density in a hydrogen microwave plasma SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID VIBRATIONAL-EXCITATION; DIAMOND DEPOSITION; CROSS-SECTIONS; KINETICS; H-2; DISSOCIATION; COEFFICIENTS AB A three-temperature thermochemical model is developed for analyzing the chemical composition and energy exchange rate coefficients are determined from cross-sectional data, assuming Maxwellian velocity distributions for electrons and heavy species mole fractions and the electron and vibrational temperatures using measured rotational temperatures. The calculations are made for three cases in which the size of the plasma is held fixed while varying the microwave power and the pressure. The vibrational temperature is shown to approach the translaitonal temperature as the pressure and power are increased. The H-atom mole fraction increases significantly with power and pressure, wheras the ion fraction and rhe electron temperature tend to decrease. The calculated H-atom fractions compare well with measured values. C1 UNIV PARIS 13,LAB INGN MAT & HAUTES PRESS,F-93430 VILLETANEUSE,FRANCE. OFF NATL ETUD & RECH AEROSP,F-92322 CHATILLON,FRANCE. RP Scott, CD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 33 TC 25 Z9 25 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1996 VL 10 IS 3 BP 426 EP 435 DI 10.2514/3.807 PG 10 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA UY335 UT WOS:A1996UY33500006 ER PT J AU Englehart, AN McConley, MW Chubb, DL AF Englehart, AN McConley, MW Chubb, DL TI Emittance measurements for a thin liquid sheet flow SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article C1 MIT,DRAPER LAB,CAMBRIDGE,MA 02139. NASA,LEWIS RES CTR,PHOTOVOLTAICS BRANCH,CLEVELAND,OH 44135. RP Englehart, AN (reprint author), CLEVELAND STATE UNIV,DEPT ELECT ENGN,1983 E 24TH ST,CLEVELAND,OH 44115, USA. NR 10 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 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1996 VL 10 IS 3 BP 547 EP 549 DI 10.2514/3.827 PG 3 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA UY335 UT WOS:A1996UY33500026 ER PT J AU Sanger, NL AF Sanger, NL TI Design of a low aspect ratio transonic compressor stage using CFD techniques SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 39th International Gas Turbine and Aeroengine Congress and Exposition CY JUN 13-16, 1994 CL THE HAGUE, NETHERLANDS ID FLOW AB A transonic compressor stage has been designed for the Naval Postgraduate School Turbopropulsion Laboratory. The design relied heavily on CFD techniques while minimizing conventional empirical design methods. The low aspect ratio (1.2) rotor has been designed for a specific head ratio of 0.25 and a tip relative inlet Mach number of 1.3. Overall stage pressure ratio is 1.56. The rotor was designed using an Euler code augmented by a distributed body force model to account for viscous effects. This provided a relatively quick-running design tool, and was used for both rotor and stator calculations. The initial stator sections were sized using a compressible, cascade panel code. In addition to being used as a case study for teaching purposes, the compressor stage will be used as a research stage. Detailed measurements, including nonintrusive LDV, will be compared with the design computations, and with the results of other CFD codes, as a means of assessing and improving the computational codes as design tools. RP Sanger, NL (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 14 TC 10 Z9 10 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD JUL PY 1996 VL 118 IS 3 BP 479 EP 491 PG 13 WC Engineering, Mechanical SC Engineering GA UY735 UT WOS:A1996UY73500011 ER PT J AU Giel, PW Sirbaugh, JR Lopez, I VanFossen, GJ AF Giel, PW Sirbaugh, JR Lopez, I VanFossen, GJ TI Three-dimensional Navier-Stokes analysis and redesign of an imbedded bellmouth nozzle in a turbine cascade inlet section SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 39th International Gas Turbine and Aeroengine Congress and Exposition CY JUN 13-16, 1994 CL THE HAGUE, NETHERLANDS AB Experimental measurements in the inlet of a transonic turbine blade cascade showed unacceptable pitchwise flow nonuniformity. A three-dimensional, Navier-Stokes computational fluid dynamics (CFD) analysis of the imbedded bellmouth inlet in the facility was performed to identify and eliminate the source of the flow nonuniformity. The blockage and acceleration effects of the blades were accounted for by specifying a periodic static pressure exit condition interpolated from a separate three-dimensional Navier-Stokes CFD solution of flow around a single blade in an infinite cascade. Calculations of the original inlet geometry showed total pressure loss regions consistent in strength and location to experimental measurements. The results indicate that the distortions were caused by a pair of streamwise vortices that originated as a result of the interaction of the flow with the imbedded bellmouth. Computations were performed for an inlet geometry that eliminated the imbedded bellmouth by bridging the region between it and the upstream wall. This analysis indicated that eliminating the imbedded bellmouth nozzle also eliminates the pair of vortices, resulting in a flow with much greater pitchwise uniformity. Measurements taken with an installed redesigned inlet verify that the flow nonuniformity has indeed been eliminated. C1 USA,RES LAB,VEHICLE PROPULS DIRECTORATE,LEWIS RES CTR,CLEVELAND,OH 44135. NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. RP Giel, PW (reprint author), NYMA INC,NASA,LEWIS RES CTR,BROOKPARK,OH 44142, USA. NR 15 TC 3 Z9 3 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD JUL PY 1996 VL 118 IS 3 BP 529 EP 535 PG 7 WC Engineering, Mechanical SC Engineering GA UY735 UT WOS:A1996UY73500017 ER PT J AU Park, DG Tao, M Li, D Botchkarev, AE Fan, Z Wang, Z Mohammad, SN Rockett, A Abelson, JR Morkoc, H Heyd, AR Alterovitz, SA AF Park, DG Tao, M Li, D Botchkarev, AE Fan, Z Wang, Z Mohammad, SN Rockett, A Abelson, JR Morkoc, H Heyd, AR Alterovitz, SA TI Gate quality Si3N4 prepared by low temperature remote plasma enhanced chemical vapor deposition for III-V semiconductor-based metal-insulator-semiconductor devices SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID CYCLOTRON RESONANCE PLASMA; THIN-FILM TRANSISTORS; SILICON-NITRIDE; ELECTRICAL-PROPERTIES; HYDROGEN CONTENT; A-SIH; STATES; PERFORMANCE; INTERFACE; STABILITY AB We report the properties of silicon nitride films deposited by the electron cyclotron resonance remote plasma enhanced chemical vapor deposition method on Si substrates using SiH4 and N-2. The effects of nitrogen/silane gas ratio (R=N-2/SiH4), electron cyclotron resonance power, substrate temperature, and H on growth, refractive index, chemical composition, and etch rate were investigated. Nominally stoichiometric Si3N4 films were obtained with a refractive index of 1.9 similar to 2.0 at a wavelength of 632.8 nm. The etch rate of the films in a buffered HF solution (7:1) was low (similar to 0.7 nm/min) and increased with increasing H-2 gas flow rate and decreasing substrate temperature during deposition. Fourier transform infrared spectroscopy and high temperature thermal evolution experiments showed very small amounts of H in the films. A leakage current less than 100 pA/cm(2) at a field of 2 MV/cm, a resistivity of >4x10(17) Omega cm, and breakdown strengths of 6-11 MV/cm at a current density of 1 mu A/cm(2) were observed. These properties are comparable to those of Si3N4 prepared by conventional high temperature (700 degrees C) chemical vapor deposition. The performance of GaAs-based field-effect-transistors in switching and power applications can be enhanced substantially by employing a metal-insulator-semiconductor structure. By taking advantage of an in situ process approach, insulator-GaAs structures were successfully gated with excellent interfacial properties. (C) 1996 American Vacuum Society. C1 UNIV ILLINOIS,COORDINATED SCI LAB,URBANA,IL 61801. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Park, DG (reprint author), UNIV ILLINOIS,MAT RES LAB,URBANA,IL 61801, USA. RI Rockett, Angus/A-3218-2008; Schaff, William/B-5839-2009; Rockett, Angus/B-5539-2013 OI Rockett, Angus/0000-0001-9759-8421 NR 43 TC 54 Z9 55 U1 0 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD JUL-AUG PY 1996 VL 14 IS 4 BP 2674 EP 2683 DI 10.1116/1.589003 PG 10 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA VD931 UT WOS:A1996VD93100041 ER PT J AU Poet, SE Skilling, DE Megyesi, JL Gilmartin, WG Smith, AW AF Poet, SE Skilling, DE Megyesi, JL Gilmartin, WG Smith, AW TI Detection of a non-cultivatable calicivirus from the white tern (Gygis alba rothschildi) SO JOURNAL OF WILDLIFE DISEASES LA English DT Article DE calicivirus; white tern; Gygis alba; cDNA hybridization ID VIRUS; STORY; SEALS; WHALE; OCEAN AB In April 1992, on Tern Island, French Frigate Shoals, Hawaii (USA), researchers observed a hand-reared white tern hatchling (Gygis alba rothschildi) develop vesicular lesions on the webbing between its toes, 6 days after falling out of its nest. Vesicular fluid collected from the foot lesions contained virus-like particles having typical calicivirus morphology. Calicivirus RNA was detected in the vesicular fluid by dot hybridization with a group-specific calicivirus copy DNA probe. Attempts to cultivate the virus in African green monkey kidney cells and porcine kidney cells were unsuccessful. This is the first report of a calicivirus infection associated with vesicular disease in a wild avian species. C1 OREGON STATE UNIV,COLL VET MED,CORVALLIS,OR 97331. NATL MARINE FISHERIES SERV,HONOLULU,HI 96822. FISH & WILDLIFE SERV,HONOLULU,HI 96850. NR 35 TC 10 Z9 10 U1 0 U2 1 PU WILDLIFE DISEASE ASSN, INC PI LAWRENCE PA 810 EAST 10TH ST, LAWRENCE, KS 66044-8897 SN 0090-3558 J9 J WILDLIFE DIS JI J. Wildl. Dis. PD JUL PY 1996 VL 32 IS 3 BP 461 EP 467 PG 7 WC Veterinary Sciences SC Veterinary Sciences GA UX347 UT WOS:A1996UX34700007 PM 8827672 ER PT J AU Doran, PT McKay, CP Adams, WP English, MC Wharton, RA Meyer, MA AF Doran, PT McKay, CP Adams, WP English, MC Wharton, RA Meyer, MA TI Climate forcing and thermal feedback of residual lake-ice covers in the high Arctic SO LIMNOLOGY AND OCEANOGRAPHY LA English DT Article; Proceedings Paper CT Symposium on Regional Assessment of Freshwater Ecosystems and Climate Change in North America CY OCT 24-26, 1994 CL LEESBURG, VA SP Amer Soc Limnol & Oceanog, N Amer Benthol Soc, US EPA, US Geol Survey ID ANTARCTIC LAKE; THICKNESS; ISLAND AB A discontinuous ice coverage and lake temperature record of 36-yr duration has been compiled for Colour Lake (79 degrees 25'N, 90 degrees 45'W) on Axel Heiberg Island, Northwest Territories. About once every 6 yr, the ice cover remains through the entire summer, creating a residual ice cover the following winter. Residual ice covers are more frequent in the last 10 yr (1986-1995) than in the 20 yr from 1959 to 1978, indicating a reduction in climate factors controlling ice decay. These factors are identified as the number of thawing degree-days, suggesting a tendency toward cooler summers over the last decade. We report year-round meteorology observations that indicate a mean annual temperature of about -15.2 degrees C, with similar to 500 thawing degree-days in summer. Following a residual ice year, spring lake-water temperatures are significantly greater than they are following nonresidual years. The increased temperatures can be attributed to the stabilizing effect of the residual ice pan the previous fall. Without an ice pan, convection cools the entire water column before the surface freezes. When the lake has an ice pan at the start of freezing, the surface freezes over quickly, effectively trapping water heated during summer. The warmer spring water temperatures act as negative feedback, decreasing the potential for a second consecutive residual ice year. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. TRENT UNIV,WATERSHED ECOSYST PROGRAM,PETERBOROUGH,ON K9J 7B8,CANADA. WILFRID LAURIER UNIV,DEPT GEOG,WATERLOO,ON N2L 3C5,CANADA. RP Doran, PT (reprint author), UNIV NEVADA,DESERT RES INST,CTR BIOL SCI,POB 60220,RENO,NV 89506, USA. NR 36 TC 41 Z9 41 U1 1 U2 5 PU AMER SOC LIMNOLOGY OCEANOGRAPH PI LAWRENCE PA 810 EAST 10TH ST, LAWRENCE, KS 66044-8897 SN 0024-3590 J9 LIMNOL OCEANOGR JI Limnol. Oceanogr. PD JUL PY 1996 VL 41 IS 5 BP 839 EP 848 PG 10 WC Limnology; Oceanography SC Marine & Freshwater Biology; Oceanography GA VN458 UT WOS:A1996VN45800005 ER PT J AU Zhu, LP Elishakoff, I Starnes, JH AF Zhu, LP Elishakoff, I Starnes, JH TI Derivation of multi-dimensional ellipsoidal convex model for experimental data SO MATHEMATICAL AND COMPUTER MODELLING LA English DT Article DE convex modeling; experimental data; uncertainty analysis ID IMPERFECTION AB This paper deals with determination of the best ellipsoidal model fitting the available limited experimental data. The problem is defined as that of finding the minimum volume ellipsoid containing all experimental data. A general transformation matrix for the rotation of N-dimensional coordinate system is first obtained by the Gramm-Schmidt orthogonalization procedure. The use of this matrix makes it possible to search in all possible directions to find an ellipsoid with a minimum volume. The general procedure is illustrated by examples in which the real data is utilized. An invariance property of the response with uncertain parameters of different physical nature is also discussed. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23664. RP Zhu, LP (reprint author), FLORIDA ATLANTIC UNIV,DEPT MECH ENGN,BOCA RATON,FL 33431, USA. NR 14 TC 18 Z9 19 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0895-7177 J9 MATH COMPUT MODEL JI Math. Comput. Model. PD JUL PY 1996 VL 24 IS 2 BP 103 EP 114 DI 10.1016/0895-7177(96)00094-5 PG 12 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA VB762 UT WOS:A1996VB76200010 ER PT J AU Jackson, AS Wier, LT Ayers, GW Beard, EF Stuteville, JE Blair, SN AF Jackson, AS Wier, LT Ayers, GW Beard, EF Stuteville, JE Blair, SN TI Changes in aerobic power of women, ages 20-64 yr SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Article DE aging; body composition; exercise epidemiology; maximal oxygen uptake; physical activity ID ALL-CAUSE MORTALITY; MAXIMAL OXYGEN INTAKE; PHYSICAL-ACTIVITY; MEN; EXERCISE; REDUCTION; CAPACITY; FITNESS; HEALTHY; RESPONSES AB This study quantified and compared the cross-sectional and longitudinal influence of age, self-report physical activity (SR-PA), and body composition (%fat) on the decline of maximal aerobic power (VO2peak) of women. The cross-sectional sample consisted of 409 healthy women, ages 20-64 yr. The 43 women of the longitudinal sample were from the same population and examined twice, the mean time between tests was 3.7 (+/-2.2) yr. Peak oxygen uptake was determined by indirect calorimetry during a maximal treadmill test. The zero-order correlation of -0.742 between VO2peak and %fat was significantly (P < 0.05) higher then the SR-PA (r = 0.626) and age correlations (r = -0.633). Linear regression defined the cross-sectional age-related decline in VO2peak at 0.537 ml . kg(-1). min(-1). yr(-1). Multiple regression analysis (R = 0.851) showed that adding %fat and SR-PA and their interaction to the regression model reduced the age regression weight of -0.537, to -0.265 ml . kg(-1). min(-1). yr(-1). Statistically controlling for time differences between tests, general linear models analysis showed that longitudinal changes in aerobic power were due to independent changes in %fat and SR-PA, confirming the cross-sectional results. These findings are consistent with men's data from the same lab showing that about 50% of the cross-sectional age-related decline in VO2peak was due to %fat and SR-PA. C1 NASA,LYNDON B JOHNSON SPACE CTR,KELSEY SEYBOLD CLIN,CARDIOPULM LAB,HOUSTON,TX 77058. INST AEROBICS RES,DALLAS,TX 75230. RP Jackson, AS (reprint author), UNIV HOUSTON,DEPT HLTH & HUMAN PERFORMANCE,COLL EDUC,HOUSTON,TX 77204, USA. NR 42 TC 76 Z9 78 U1 0 U2 6 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD JUL PY 1996 VL 28 IS 7 BP 884 EP 891 DI 10.1097/00005768-199607000-00016 PG 8 WC Sport Sciences SC Sport Sciences GA UZ387 UT WOS:A1996UZ38700016 PM 8832543 ER PT J AU Sandford, SA AF Sandford, SA TI The inventory of interstellar materials available for the formation of the solar system SO METEORITICS & PLANETARY SCIENCE LA English DT Review ID POLYCYCLIC AROMATIC-HYDROCARBONS; INTERPLANETARY DUST PARTICLES; DENSE MOLECULAR CLOUDS; TIME-DEPENDENT CHEMISTRY; MICRON SPECTROPHOTOMETRIC OBSERVATIONS; HYDROGENATED AMORPHOUS-CARBON; INFRARED TRANSMISSION SPECTRA; GALACTIC-CENTER; GRAIN MANTLES; ICE ANALOGS AB Tremendous progress has been made in the field of interstellar dust in recent years through the use of telescopic observations, theoretical studies, laboratory studies of analogs, and the study of actual interstellar samples found in meteorites. It is increasingly clear that the interstellar medium (ISM) contains an enormous diversity of materials created by a wide range of chemical and physical processes. This understanding is a far cry from the picture of interstellar materials held as recently as two decades ago, a picture which incorporated only a few generic types of grains and few molecules. In this paper, I attempt to review some of our current knowledge of the more abundant materials thought to exist in the ISM. The review concentrates on matter in interstellar dense molecular clouds since it is the materials in these environments from which new stars and planetary systems are formed. However, some discussion is reserved for materials in circumstellar environments and in the diffuse ISM. The paper also focuses largely on solid materials as opposed to gases since solids contain a major fraction of the heavier elements in clouds and because solids are most likely to survive incorporation into new planetary systems in identifiable form. The paper concludes with a discussion of some of the implications resulting from the recent growth of our knowledge about interstellar materials and also considers a number of areas in which future work might be expected to yield important results. RP NASA, AMES RES CTR, ASTROPHYS BRANCH, MAIL STOP 245-6, MOFFETT FIELD, CA 94035 USA. NR 255 TC 86 Z9 88 U1 0 U2 4 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 1086-9379 EI 1945-5100 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD JUL PY 1996 VL 31 IS 4 BP 449 EP 476 PG 28 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UX180 UT WOS:A1996UX18000006 PM 11541166 ER PT J AU Zolensky, ME Ivanov, AV Yang, SV Mittlefehldt, DW Ohsumi, K AF Zolensky, ME Ivanov, AV Yang, SV Mittlefehldt, DW Ohsumi, K TI The Kaidun meteorite: Mineralogy of an unusual CM1 lithology SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID CARBONACEOUS CHONDRITE GROUP; ASSEMBLAGES; MATRIX; SOLAR AB Kaidun is a breccia of disparate enstatite and carbonaceous chondrite clasts that continues to provide real surprises. Many Kaidun clasts have been intensely altered by aqueous fluids, as evidenced by the widespread occurrence of ferromagnesian phyllosilicates and by the presence of carbonate- and phyllosilicate-filled veins. In this report, we describe an unusual CM lithology containing many mineralogical features not previously reported from any meteorite, including pyrrhotite, with exclusive needlelike morphologies and thick mantles of phyllosilicate, and complex aggregates of phyllosilicate, melanite garnet, crosscut by pentlandite veins. The latter features appear to be due in large part to extensive hydrothermal alteration at temperatures on the order of 450 degrees C, which is significantly higher than that attained during secondary processing from other known CM material. C1 RUSSIAN ACAD SCI,VI VERNADSKII GEOCHEM & ANAL CHEM INST,MOSCOW 117975,RUSSIA. LOCKHEED MARTIN ENGN & SCI CO,HOUSTON,TX 77058. NATL INST HIGH ENERGY PHYS,PHOTON FACTORY,TSUKUBA,IBARAKI 305,JAPAN. RP Zolensky, ME (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SN2,HOUSTON,TX 77058, USA. NR 45 TC 38 Z9 39 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METORIT PLANET SCI JI Meteorit. Planet. Sci. PD JUL PY 1996 VL 31 IS 4 BP 484 EP 493 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UX180 UT WOS:A1996UX18000008 ER PT J AU Zolensky, ME Weisberg, MK Buchanan, PC Mittlefehldt, DW AF Zolensky, ME Weisberg, MK Buchanan, PC Mittlefehldt, DW TI Mineralogy of carbonaceous chondrite clasts in HED achondrites and the Moon SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID CM-CHONDRITES; PARENT BODY; COMPOSITIONAL CLASSIFICATION; BASALTIC ACHONDRITES; BHOLGHATI HOWARDITE; SHOCK METAMORPHISM; AQUEOUS ALTERATION; DARK CLASTS; METEORITES; PETROLOGY AB The majority of the carbonaceous chondrite clasts found in howardites, eucrites and diogenites are CM2 material, a lesser proportion is CR2 material, and other rare types are present. A single clast that was found on the Moon and called the Bench Crater meteorite is apparently shocked CM1 material. The CM2 clasts are matrix supported mixtures of olivine-pyroxene-phyllosilicate-sulfide bearing aggregates, loose olivines and pyroxenes, sulfides, carbonates, and sinuous spinel-phyllosilicate-diopside calcium-aluminum-rich inclusions (CAIs). Magnetite and metal are rare. Some aggregates have fine-grained rims of material resembling matrix. The opaque, fine-grained matrix consists predominantly of serpentine of extremely variable composition and sulfides; tochilinite is occasionally present. The trace element data for one Jodzie clast from this study and the average of similar clasts from Kapoeta support a CM classification; volatiles are depleted relative to CI and enriched relative to CR material. The CR2 clasts are found (in small numbers) in only four howardites: Bholghati, Jodzie, Kapoeta and Y793497. Petrographically, they are matrix-supported mixtures of olivine aggregates (sometimes containing sulfides), loose olivines, pyrrhotite, pentlandite, low-Ca pyroxene (minor), hedenbergite (rare), kamacite (rare and only found within olivine), Ca-carbonates and abundant magnetite framboids and plaquets. Phyllosilicates are fine-grained and largely confined to matrix; they are mixtures of serpentine and saponite. The matrix of CR2 clasts also contains pyrrhotite, pentlandite, chromite and a significant fraction of poorly-crystalline material with the same bulk composition as matrix phyllosilicate. There is evidence of heating in a substantial number of clasts, both CM2 and CR2, including: (1) corrugated serpentine flakes, (2) pseudomorphs of anhydrous ferromagnesian material after flaky phyllosilicates, and (3) hedenbergite rims on calcite. While the timing of the hedenbergite rims is debatable, the destruction of phyllosilicates clearly occurred at a late stage, plausibly during impact onto the HED asteroid(s) and Moon, and required peak heating temperatures on the order of 400 degrees C. We note that in general, CM2 material was the most common carbonaceous chondrite lithology impacting the HED asteroids (with howardites and eucrites taken together), as it is for the Earth today. A total of 61 out of 75 carbonaceous chondrite clasts from HED meteorites belong to the CM clan, petrologic grade 2. This is also supported by published siderophile and volatile element data on howardites, eucrites and diogenites that are taken to indicate that CM-like materials were the most common impactors on the HED asteroid(s). The ratio of CR/CM clasts in HED asteroids is essentially the same as for modern falls at Earth. This may indicate that the ratio of disaggregated CM2 to CR2 asteroidal material has been approximately constant through the history of the solar system. Finally, our results are also compatible with type-2 carbonaceous chondrites being equivalent to or from the same source as the material that originally accreted to form the HED asteroid. C1 AMER MUSEUM NAT HIST, DEPT EARTH & PLANETARY SCI, NEW YORK, NY 10024 USA. UNIV HOUSTON, DEPT GEOSCI, HOUSTON, TX 77204 USA. LOCKHEED ENGN & SCI CO, HOUSTON, TX 77058 USA. RP Zolensky, ME (reprint author), NASA, LYNDON B JOHNSON SPACE CTR, DIV EARTH SCI & SOLAR SYST EXPLORAT, HOUSTON, TX 77058 USA. NR 71 TC 120 Z9 120 U1 1 U2 19 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 JUL PY 1996 VL 31 IS 4 BP 518 EP 537 PG 20 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UX180 UT WOS:A1996UX18000011 ER PT J AU Ringwald, FA Naylor, T Mukai, K AF Ringwald, FA Naylor, T Mukai, K TI The optical spectra of old novae SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; atlases; binaries, close; novae, cataclysmic variables; white dwarfs ID CATACLYSMIC VARIABLES; OPTIMAL EXTRACTION; CLASSICAL NOVAE; DWARF NOVAE; HIBERNATION; EVOLUTION; BINARIES; SPECTROSCOPY AB A collection of low-resolution optical spectra of classical novae is presented. The novae were selected from the atlas of Duerbeck, are northern and equatorial, and erupted between 1783 and. 1986. About half the objects at the nominal positions of the novae show stellar or featureless and often red spectra, making their identifications uncertain. Among novae that were positively identified, there is evidence of variability, but that on short time-scales is at least as important as that on time-scales of decades. Indeed, descriptions by Humason in 1938, McLaughlin in 1953, Greenstein in 1960, and Kraft in 1964 are remarkably current: the only clear change on long time-scales is the fading of the nebular lines. Several lines of evidence suggest the effects of irradiation of the accretion discs by hot white dwarfs. C1 PLANETARY SCI INST,TUCSON,AZ 85705. UNIV KEELE,DEPT PHYS,KEELE ST5 5BG,STAFFS,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RI Naylor, Tim /A-9465-2015 NR 63 TC 52 Z9 52 U1 0 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUL 1 PY 1996 VL 281 IS 1 BP 192 EP 210 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW119 UT WOS:A1996UW11900017 ER PT J AU Meikle, WPS Cumming, RJ Geballe, TR Lewis, JR Walton, NA Balcells, M Cimatti, A Croom, SM Dhillon, VS Economou, F Jenkins, CR Knapen, JH Lucey, JR Meadows, VS Morris, PW PerezFournon, I Shanks, T Smith, LJ Tanvir, NR Veilleux, S Vilchez, J Wall, JV AF Meikle, WPS Cumming, RJ Geballe, TR Lewis, JR Walton, NA Balcells, M Cimatti, A Croom, SM Dhillon, VS Economou, F Jenkins, CR Knapen, JH Lucey, JR Meadows, VS Morris, PW PerezFournon, I Shanks, T Smith, LJ Tanvir, NR Veilleux, S Vilchez, J Wall, JV TI An early-time infrared and optical study of the type Ia supernovae SN 1994D and 1991T SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE stars, general; supernovae, individual, SN1991T; supernovae, individual, SN1994D; infrared, stars ID DETONATION MODELS; LIGHT CURVES; WHITE-DWARF; SN-1991T; SPECTRA; NUCLEOSYNTHESIS; SPECTROSCOPY; ULTRAVIOLET; PHOTOMETRY; EXTRACTION AB We present early-time infrared (IR) and optical spectroscopy, and optical photometry, of the Type Ia supernova 1994D. These observations provide the most complete optical-IR spectral coverage ever achieved for a Type Ia at this phase. Optical and IR spectra were obtained as early as 9 d before maximum light. The combined optical and IR spectra of SN 1994D reveal a flux 'deficit' in the R, I and J bands as early as maximum light, They also illustrate the dramatic deepening of the J-band deficit after maximum light. We also present a maximum light IR spectrum of the peculiar Type Ia SN 1991T. This also shows a deficit in the J band, but it does not show such a pronounced deficit in the R and I bands as SN 1994D. Both supernovae show a P Cygni-like feature with the absorption at similar to 1.05 mu m and the emission at similar to 1.08 mu m. In SN 1994D the absorption shows no wavelength shift during the period between -8.5 and -1.5 d before maximum light. After this the feature rapidly weakened. We argue that, in this event, the P Cygni line feature formed in a discrete shell-like zone lying above the photosphere. In SN 1991T a continuous, shallow density gradient scattering zone seems more appropriate. For both supernovae we explore possible identifications with He I 1.0830 mu m and Mg II 1.0926 mu m, but there are difficulties with either option. In SN 1994D it may be that the feature is actually the result of a blend of the helium and magnesium lines. However, for both supernovae it is not ruled out that the J-band feature is really the result of a transition in one or more unidentified species. Consideration of the velocities associated with the feature indicates that, if its origin is helium, then in SN 1994D it is more likely that it formed in the alpha-rich freeze-out, but some mixing to higher velocities is also required. In contrast, in SN 1991T we favour an origin in the form of a residual or accreted layer on the surface of the progenitor white dwarf. If the feature is due to magnesium then the derived velocities for SN 1994D are in good agreement with the predictions of explosion model W7. In SN 1991T, identification with magnesium presents problems in accounting for the inferred velocity structure. C1 STOCKHOLM OBSERV, S-13336 SALTSJOBADEN, SWEDEN. JOINT ASTRON CTR, HILO, HI 96720 USA. ROYAL GREENWICH OBSERV, CAMBRIDGE CB3 0EZ, ENGLAND. KAPTEYN ASTRON INST, 9700 AV GRONINGEN, NETHERLANDS. OSSERV ASTROFIS ARCETRI, I-50125 FLORENCE, ITALY. UNIV DURHAM, DEPT PHYS, DURHAM DH1 3LE, ENGLAND. UNIV MONTREAL, DEPT PHYS, MONTREAL, PQ H3C 3J7, CANADA. OBSERV ASTRON MT MEGANTIC, NOTRE DAME DES BOIS, PQ J0B 2E0, CANADA. ROYAL GREENWICH OBSERV, E-38780 SANTA CRUZ PALMA, TENERIFE, SPAIN. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. INST ASTROFIS CANARIAS, E-38200 LA LAGUNA, TENERIFE, SPAIN. UNIV LA LAGUNA, DEPT ASTROFIS, TENERIFE, SPAIN. UNIV LONDON UNIV COLL, DEPT PHYS & ASTRON, LONDON WC1E 6BT, ENGLAND. UNIV CAMBRIDGE, INST ASTRON, CAMBRIDGE CB3 0HA, ENGLAND. UNIV MARYLAND, DEPT ASTRON, COLLEGE PK, MD 20742 USA. RP Meikle, WPS (reprint author), UNIV LONDON IMPERIAL COLL SCI & TECHNOL, BLACKETT LAB, ASTROPHYS GRP, PRINCE CONSORT RD, LONDON SW7 2BZ, ENGLAND. OI Vilchez, J. M./0000-0001-7299-8373 NR 78 TC 83 Z9 83 U1 0 U2 2 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 JUL 1 PY 1996 VL 281 IS 1 BP 263 EP 280 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW119 UT WOS:A1996UW11900024 ER PT J AU Lyne, AG Kaspi, VM Bailes, M Manchester, RN Taylor, H Arzoumanian, Z AF Lyne, AG Kaspi, VM Bailes, M Manchester, RN Taylor, H Arzoumanian, Z TI A giant glitch in PSR B17S7-24 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Letter DE pulsars, individuals, PSR 1757-24; stars, neutron ID G5.4-1.2; PULSARS AB One of the largest known glitches has been detected in the young pulsar PSR B1757-24. The glitch occurred around MJD 49476 and was characterized by a fractional increase in rotation rate of 2x10(-6). It was followed by a small exponential-like relaxation with a time-scale of similar to 40 d, together with a longer term recovery. Such large glitches have been seen in only about six other pulsars of the 700 presently known, The size of the glitch and the post-glitch behaviour are similar to those of other pulsars of the same age. In this pulsar, we find that about 1.5 per cent of the angular momentum of the pulsar is released to the crust of the neutron star erratically, suggesting that at least this fraction of the moment of inertia of the star is in the form of superfluid neutrons. C1 CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. RP Lyne, AG (reprint author), UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,JODRELL BANK,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. NR 12 TC 12 Z9 12 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUL 1 PY 1996 VL 281 IS 1 BP L14 EP L16 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UW119 UT WOS:A1996UW11900004 ER PT J AU Kay, KQ Swanson, DC AF Kay, KQ Swanson, DC TI Error in bending wave power measurements resulting from longitudinal waves SO NOISE CONTROL ENGINEERING JOURNAL LA English DT Article AB Bending wave power in the ''far field'' of a beam is often estimated with two closely spaced accelerometers. When measuring power in flows consisting of bending waves only, this method has been shown to provide reliable results. However, in most practical measurement cases some level of longitudinal wave flow will be present. Measuring bending wave power flow in a beam that has a significant level of longitudinal wave flow can provide inaccurate results, particularly when techniques using measurements on only one side of the beam are used. To determine the limitations of one of the most commonly used one-sided bending power measurements (the two-accelerometer two-position linear finite difference estimate), a measurement on a beam is modeled for combined longitudinal and bending wave power flow. This information is used to predict the sensitivity of the basic two-accelerometer technique to longitudinal wave errors in bending wave measurements on a 1.524 mx0.1016 mx0.1016 m 7075-T651 aluminum beam. (C) 1996 Institute of Noise Control Engineering. RP Kay, KQ (reprint author), VIRGINIA POLYTECH INST & STATE UNIV,VCES,NASA,LANGLEY RES CTR,MS463,HAMPTON,VA 23681, USA. NR 7 TC 3 Z9 3 U1 0 U2 1 PU INST NOISE CONTROL ENG PI POUGHKEEPSIE PA PO BOX 3206 ARLINGTON BRANCH, POUGHKEEPSIE, NY 12603 SN 0736-2501 J9 NOISE CONTROL ENG JI Noise Control Eng. J. PD JUL-AUG PY 1996 VL 44 IS 4 BP 185 EP 192 DI 10.3397/1.2828400 PG 8 WC Acoustics; Engineering, Multidisciplinary SC Acoustics; Engineering GA VH294 UT WOS:A1996VH29400002 ER PT J AU Kozusko, F Grosch, CE Jackson, TL Kennedy, CA Gatski, TB AF Kozusko, F Grosch, CE Jackson, TL Kennedy, CA Gatski, TB TI The structure of variable property, compressible mixing layers in binary gas mixtures SO PHYSICS OF FLUIDS LA English DT Article ID FREE SHEAR LAYERS; DENSITY AB We present the results of a study of the structure of a parallel compressible mixing layer in a binary mixture of gases. The gases included in this study are hydrogen (H-2), helium (He), nitrogen (N-2), oxygen (O-2), neon (Ne) and argon (Ar). Profiles of the variation of the Lewis and Prandtl numbers across the mixing layer for all 30 combinations of gases are given. It is shown that the Lewis number can vary by as much as a factor of 8 and the Prandtl number by a factor of 2 across the mixing layer. Thus assuming constant values for the Lewis and Prandtl numbers of a binary gas mixture in the shear layer, as is done in many theoretical studies, is a poor approximation. We also present profiles of the velocity, mass fraction, temperature and density for representative binary gas mixtures at zero and supersonic Mach numbers. We show that the shape of these profiles is strongly dependent on which gases are in the mixture as well as on whether the denser gas is in the fast stream or the slow stream. (C) 1996 American Institute of Physics. C1 OLD DOMINION UNIV,DEPT MATH & STAT,NORFOLK,VA 23529. OLD DOMINION UNIV,DEPT OCEANOG & COMP SCI,NORFOLK,VA 23529. NASA,LANGLEY RES CTR,INST COMP APPL SCI & ENGN,HAMPTON,VA 23681. SANDIA NATL LABS,COMBUST RES FACIL,LIVERMORE,CA 94551. NASA,LANGLEY RES CTR,AERODYNAM & ACOUST METHODS BRANCH,HAMPTON,VA 23681. NR 21 TC 8 Z9 8 U1 0 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD JUL PY 1996 VL 8 IS 7 BP 1945 EP 1953 DI 10.1063/1.869103 PG 9 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA UU385 UT WOS:A1996UU38500027 ER PT J AU Kozusko, F Lasseigne, DG Grosch, CE Jackson, TL AF Kozusko, F Lasseigne, DG Grosch, CE Jackson, TL TI The stability of compressible mixing layers in binary gases SO PHYSICS OF FLUIDS LA English DT Article ID INVISCID SPATIAL STABILITY; SHEAR-LAYER AB We present the results of a study of the inviscid two-dimensional spatial stability of a parallel compressible mixing layer in a binary gas. The parameters of this study are the Mach number of the fast stream, the ratio of the velocity of the slow stream to that of the fast stream, the ratio of the temperatures, the composition of the gas in the slow stream and in the fast stream, and the frequency of the disturbance wave. The ratio of the molecular weight of the slow stream to that of the fast stream is found to be an important quantity and is used as an independent variable in presenting the stability characteristics of the flow. It is shown that differing molecular weights have a significant effect on the neutral-mode phase speeds, the phase speeds of the unstable modes, the maximum growth rates, and the unstable frequency range of the disturbances. The molecular weight ratio is a reasonable predictor of the stability trends. We have further demonstrated that the normalized growth rate as a function of the convective Mach number is relatively insensitive (approximate to 25%) to changes in the composition of the mixing layer. Thus, the normalized growth rate is a key element when considering the stability of compressible mixing layers, since once the basic stability characteristics for a particular combination of gases is known at zero Mach number, the decrease in growth rates due to compressibility effects at the larger convective Mach numbers is somewhat predictable. (C) 1996 American Institute of Physics. C1 OLD DOMINION UNIV, DEPT MATH & STAT, NORFOLK, VA 23529 USA. OLD DOMINION UNIV, DEPT OCEANOG, NORFOLK, VA 23529 USA. OLD DOMINION UNIV, DEPT COMP SCI, NORFOLK, VA 23529 USA. NASA, LANGLEY RES CTR, INST COMP APPL SCI & ENGN, HAMPTON, VA 23681 USA. NR 18 TC 9 Z9 9 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD JUL PY 1996 VL 8 IS 7 BP 1954 EP 1963 DI 10.1063/1.868974 PG 10 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA UU385 UT WOS:A1996UU38500028 ER PT J AU Cole, KD AF Cole, KD TI Dielectric current in a plasma SO PHYSICS OF PLASMAS LA English DT Article AB Tile ''dielectric'' current driven by a spatially dependent, suddenly applied, electric field E orthogonal (perpendicular to) to the magnetic induction B in a collisionless plasma is investigated from first principles. Both E and B are assumed in fixed directions. The current is qualitatively different in two conditions, whether del EB(2)q/mc(2) [K. D. Cole, Planet. Space Sci. 24, 515 (1976)], where q and m are the charge and mass, respectively, of charged particles. Here the current is verified in the first condition by a new argument. Nonadiabatically (NA) established uniform electric field orthogonal to a magnetic field causes an additional time-averaged pressure in the plasma, given by rho(m)c(2)E(2)/2B(2), where rho(m) is the mass density of the plasma, and a consequent accompanying additional magnetic moment per unit volume, given by -rho(m)c(2)E(2)/2B(3). When the electric field has a gradient parallel to the field itself, there is produced a dielectric current which is balanced by a grad p current due to the pressure caused by the electric field. This analysis of the NA case leads to the identification of div D-perpendicular to, rather than div E(perpendicular to), with the net charge density, consistent with the Jean's theorem of the equivalence of free particle orbit theory with the collisionless Boltzmann equation. In turn, this identification leads to the integral relation, along a line orthogonal to B in the direction of E, whether the latter is adiabatically or nonadiabatically established, p(perpendicular to)+(B-2/8 pi)-(rho(m)c(2)E(2)/2B(2))=const, instead of the conventional relation in which the electric field term is missing. (C) 1996 American Institute of Physics. RP Cole, KD (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 9104, GREENBELT, MD 20771 USA. NR 10 TC 3 Z9 3 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-664X J9 PHYS PLASMAS JI Phys. Plasmas PD JUL PY 1996 VL 3 IS 7 BP 2717 EP 2724 DI 10.1063/1.871529 PG 8 WC Physics, Fluids & Plasmas SC Physics GA UV469 UT WOS:A1996UV46900030 ER PT J AU Jenniskens, P Blake, DF AF Jenniskens, P Blake, DF TI A mechanism for forming deep cracks in comets SO PLANETARY AND SPACE SCIENCE LA English DT Article ID WATER ICE; AMORPHOUS ICE; THERMAL-STRESSES; NUCLEI; IRRADIATION; DENSITY; SIZE AB A low temperature structural change in amorphous water ice, the high density to low density amorphous transition, is proposed as a mechanism for the formation of deep cracks in cometary nuclei. Such cracks are proposed to underlie active vents in the cometary crust and to play a role in the splitting of cometary nuclei. RP Jenniskens, P (reprint author), NASA,AMES RES CTR,MAIL STOP 239-4,MOFFETT FIELD,CA 94035, USA. NR 35 TC 11 Z9 11 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD JUL PY 1996 VL 44 IS 7 BP 711 EP 713 DI 10.1016/0032-0633(96)00054-2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA VK745 UT WOS:A1996VK74500009 ER PT J AU Ramachandra, P Ramani, R Ravichandran, TSG Ramgopal, G Gopal, S Ranganathaiah, C Murthy, NS AF Ramachandra, P Ramani, R Ravichandran, TSG Ramgopal, G Gopal, S Ranganathaiah, C Murthy, NS TI Free volume study of poly(chlorotrifluoroethylene) using positron annihilation spectroscopy as a microanalytical tool SO POLYMER LA English DT Article DE positron lifetime; free volume; lass transition temperature ID SEMICRYSTALLINE PEEK; POLYACRYLONITRILE; LIFETIME; POLYMERS AB Positron lifetimes and X-ray diffraction measurements were carried out on poly(chlorotrifluoroethylene) films annealed between 25 and 215 degrees C. The positron lifetime results were used to determine the free volume and XRD data were used to determine the apparent crystallite size and crystallinity. The glass transition temperature (T-g) of 52 degrees C obtained from positron results is in agreement with that obtained by thermal analysis. The average free volume cell size is 74 Angstrom(3) in films annealed below T-g, and increases to 84 Angstrom(3) in samples annealed above T-g. Although the observed changes in positron lifetime parameters as a function of annealing temperature are small, they are significant for the kind of material investigated. Our observations are explained in terms of thermally activated chain mobility, local relaxations and long-range motions. We further estimate, for the first time, the activation energies in the amorphous and crystalline regions of the polymer using the Goldanskii kinetic relations. Copyright (C) 1996 Elsevier Science Ltd. C1 UNIV MYSORE,DEPT STUDIES PHYS,MYSORE 570006,KARNATAKA,INDIA. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. ALLIED SIGNAL INC,MORRISTOWN,NJ 07962. NR 27 TC 20 Z9 20 U1 1 U2 3 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0032-3861 J9 POLYMER JI Polymer PD JUL PY 1996 VL 37 IS 15 BP 3233 EP 3239 DI 10.1016/0032-3861(96)88467-9 PG 7 WC Polymer Science SC Polymer Science GA UY815 UT WOS:A1996UY81500008 ER PT J AU DeKeyser, J Roth, M Lemaire, J Tsurutani, BT Ho, CM Hammond, CM AF DeKeyser, J Roth, M Lemaire, J Tsurutani, BT Ho, CM Hammond, CM TI Theoretical plasma distributions consistent with Ulysses magnetic field observations in a solar wind tangential discontinuity SO SOLAR PHYSICS LA English DT Article ID MAGNETOPAUSE STRUCTURE; AU AB The overall multi-layer structure of the magnetic field profile observed by Ulysses across a broad solar wind tangential discontinuity can be reproduced fairly well by means of a kinetic model. Such a simulation provides complementary information about the velocity distribution functions, which are not always available from the plasma experiment due to the low time resolution inherent in plasma measurements. The success of such a simulation proves that the kinetic model can be used as a realistic basis for further studies of the structure and stability of solar wind tangential disontinuities. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP DeKeyser, J (reprint author), BELGIAN INST SPACE AERON,RINGLAAN 3,B-1180 BRUSSELS,BELGIUM. NR 15 TC 6 Z9 6 U1 0 U2 0 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 JUL PY 1996 VL 166 IS 2 BP 415 EP 422 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UX481 UT WOS:A1996UX48100012 ER PT J AU Dyall, KG Faegri, K AF Dyall, KG Faegri, K TI Optimization of Gaussian basis sets for Dirac-Hartree-Fock calculations SO THEORETICA CHIMICA ACTA LA English DT Article DE basis set optimization; relativistic basis sets; Dirac-Hartree-Fock ID GTF BASIS-SETS; ROOTHAAN CALCULATIONS; SCF CALCULATIONS; ATOMS; HYDRIDES; PROGRAM; NUCLEUS; BREIT; RN AB We investigate the optimization of Gaussian basis sets for relativistic calculations within the framework of the restricted Dirac-Hartree-Fock (DHF) method for atoms. We compare results for Rn of nonrelativistic and relativistic basis set optimizations with a finite nuclear-size. Optimization of separate sets for each spin-orbit component shows that the basis set demands for the lower j component are greater than for the higher j component. In particular, the p(1/2) set requires almost as many functions as the s(1/2) set. This implies that for the development of basis sets for heavy atoms, the symmetry type for which a given number of functions is selected should be based on j, not on l, as has been the case in most molecular calculations performed to date. C1 UNIV OSLO,DEPT CHEM,N-0315 OSLO 3,NORWAY. RP Dyall, KG (reprint author), NASA,AMES RES CTR,THERMOSCI INST,MS STC 230-3,MOFFETT FIELD,CA 94035, USA. NR 44 TC 79 Z9 79 U1 1 U2 7 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0040-5744 J9 THEOR CHIM ACTA JI Theor. Chim. Acta PD JUL PY 1996 VL 94 IS 1 BP 39 EP 51 DI 10.1007/s002140050162 PG 13 WC Chemistry, Physical SC Chemistry GA VC988 UT WOS:A1996VC98800004 ER PT J AU Shogrin, B Wilbur, PJ Jones, WR HerreraFierro, P Williamson, DL AF Shogrin, B Wilbur, PJ Jones, WR HerreraFierro, P Williamson, DL TI The effects of ion implantation on the tribology of perfluoropolyether-lubricated 440C stainless steel couples SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT STLE/ASME 1995 Tribology Conference CY OCT 08-11, 1995 CL KISSIMMEE, FL SP STLE, ASME DE boundary lubrication; ion implantation; synthetic lubricants; aerospace tribology ID PERFLUOROPOLYALKYLETHER OIL; DEGRADATION; WEAR; TEMPERATURE; MOSSBAUER; SURFACES; FRICTION; BEHAVIOR; VACUUM; ENERGY AB The lubricating lifetime of thin films of a perfluoropolyether (PFPE) based on hexafluoropropene oxide in the presence of ion-implanted 440C stainless steel is presented. Stainless-steel discs, either unimplanted or implanted with N-2, C, Ti, Ti + N-2, or Ti + C, had a thin film of PFPE (60-400 Angstrom) applied to them reproducibly (+/- 20%) and uniformly (+/- 15%) using a device developed for this study. The lifetimes of these films were quantified by measuring the number of sliding-wear cycles required to induce an increase in the friction coefficient from an initial value characteristic of the lubricated wear couple to a final, or failure value, characteristic of an unlubricated, unimplanted couple. The tests were performed in a dry nitrogen atmosphere (< 1% RH) at room temperature using a 3 N normal load with a relative sliding speed of 0.05 ms(-1). The lubricating lifetime of the 440C couple was increased by an order of magnitude by implanting the disc with Ti. Ranked from most to least effective, the implanted species were Ti, Ti + C, unimplanted, N-2, C similar or equal to Ti + N-2. The mechanism postulated to explain these results involves the formation of a passivating or reactive layer which inhibits or facilitates the production of active sites. The corresponding surface microstructures induced by ion implantation, obtained using X-ray diffraction and conversion electron Mossbauer spectroscopy, ranked from most to least effective in enhancing lubricant lifetime were amorphous Fe-Cr-Ti, amorphous Fe-Cr-Ti-C + TiC, unimplanted, epsilon-(Fe,Cr)(x)N, x = 2 or 3, and amorphous Fe-Cr-C similar or equal to amorphous Fe-Cr-Ti-N. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. OHIO AEROSP INST,CLEVELAND,OH 44142. COLORADO SCH MINES,DEPT PHYS,GOLDEN,CO 80401. RP Shogrin, B (reprint author), COLORADO STATE UNIV,DEPT MECH ENGN,FT COLLINS,CO 80523, USA. NR 35 TC 2 Z9 2 U1 1 U2 1 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0569-8197 J9 TRIBOL T JI Tribol. Trans. PD JUL PY 1996 VL 39 IS 3 BP 507 EP 516 DI 10.1080/10402009608983561 PG 10 WC Engineering, Mechanical SC Engineering GA UY707 UT WOS:A1996UY70700001 ER PT J AU Morales, W AF Morales, W TI A quantum chemical study on the interaction of BF3 and hydroxyl groups with two model perfluoroethers SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT STLE/ASME 1995 Tribology Conference CY OCT 08-11, 1995 CL KISSIMMEE, FL SP STLE, ASME DE additive effects; decomposition; synthetic lubricants ID PERFLUOROPOLYETHERS; TEMPERATURES; DEGRADATION; ADSORPTION; ETHER; SITES AB A quantum chemical computational study was performed on the interaction of BF3 (a strong Lewis acid) and various OH groups, with perfluorodimethylether (PDME) and perfluorodimethylether (PDEE). The focus of this study was to gain insight on the decomposition of model perfluoro ethers on dehydroxylated alumina surfaces in order to understand the decomposition of perfluoropolyalkylether (PFPE) liquid lubricants under tribological conditions. The results indicated that surface Lewis acid sites were not responsible for perfluoroether decomposition and that surface OH groups could be involved. RP Morales, W (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 17 TC 0 Z9 0 U1 2 U2 4 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0569-8197 J9 TRIBOL T JI Tribol. Trans. PD JUL PY 1996 VL 39 IS 3 BP 587 EP 594 DI 10.1080/10402009608983570 PG 8 WC Engineering, Mechanical SC Engineering GA UY707 UT WOS:A1996UY70700010 ER PT J AU Vijayaraghavan, D Keith, TG Brewe, DE AF Vijayaraghavan, D Keith, TG Brewe, DE TI Effect of lubricant supply starvation on the thermohydrodynamic performance of a journal bearing SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT STLE/ASME 1995 Tribology Conference CY OCT 08-11, 1995 CL KISSIMMEE, FL SP STLE, ASME DE lubricant; journal bearings; heat transfer; cavitation; hydrodynamic lubrication; thermal effects; starvation ID ALGORITHM AB With judicious selection of supply groove location for journal bearings, the lubricant supply rate and power loss can be considerably reduced without sacrificing the load-carrying capacity. In addition, the lubricant supply rate can further be reduced, either accidentally or deliberately, and the applied load may still be maintained. In this parametric study, the effects of reduced lubricant supply rate compared to the flooded inlet is studied for an axial-grooved journal bearing Cavitation effects in the fluid film are taken into account and a full THD model, including heat conduction to the metal surfaces, is included in the analysis. Performance parameters at various load values due to reduced supply rate and typical temperature distributions are presented. It is found that, it may be possible to operate the bearing with as much as 70 percent reduction in lubricant supply rate. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP Vijayaraghavan, D (reprint author), UNIV TOLEDO, DEPT MECH ENGN, TOLEDO, OH 43606 USA. NR 19 TC 8 Z9 8 U1 0 U2 2 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0569-8197 J9 TRIBOL T JI Tribol. Trans. PD JUL PY 1996 VL 39 IS 3 BP 645 EP 653 DI 10.1080/10402009608983578 PG 9 WC Engineering, Mechanical SC Engineering GA UY707 UT WOS:A1996UY70700018 ER PT J AU Benoy, PA Dellacorte, C AF Benoy, PA Dellacorte, C TI Au/Cr sputter coating for the protection of alumina during sliding at high temperatures SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT STLE/ASME 1995 Tribology Conference CY OCT 08-11, 1995 CL KISSIMMEE, FL SP STLE, ASME DE solid lubrication; gold; chromium; ceramics; high temperatures ID SILVER COATINGS; FILMS AB A sputter-deposited bilayer coating of gold and chromium was investigated as a potential solid lubricant to protect alumina substrates in applications involving sliding at high temperatures. The lubricant was tested in a Pin-on-disk tribometer with coated alumina disks sliding against uncoated alumina pins. Three test parameters-tenperature, load and sliding velocity-were varied over a wide range in order to determine the performance envelope of the Au/Cr solid lubricant film. The tribo-tests were run in air al temperatures of 25 degrees to 1000 degrees C, under loads of 4.9 to 490 N and al sliding velocities from 1 to 15 ms(-1). Posttest analyses included surface profilometry, wear factor determination and SEM/EDS examination of worn surfaces. Compared to unlubricated Al2O3 sliding, the use of the Au/Cr film reduced friction by 30 to 50 percent and wear by one to true orders of magnitude. Increases in test temperature resulted in lower friction and the Au/Cr film continued to provide low friction, about 0.3, even at 1000 degrees C. Pin wear factors and friction were largely unaffected by increasing loads up to 29.4 N. Sliding velocity had essentially no effect on friction, however, increased velocity reduced coating life (total sliding distance). Based upon these research results, the Au/Cr film is a promising lubricant for moderately loaded, low speed applications operating at temperatures as high as 1000 degrees C. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP Benoy, PA (reprint author), ST LOUIS UNIV,PARKS COLL,CAHOKIA,IL 62206, USA. NR 15 TC 1 Z9 1 U1 1 U2 3 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0569-8197 J9 TRIBOL T JI Tribol. Trans. PD JUL PY 1996 VL 39 IS 3 BP 670 EP 676 DI 10.1080/10402009608983581 PG 7 WC Engineering, Mechanical SC Engineering GA UY707 UT WOS:A1996UY70700021 ER PT J AU Mathe, N Chen, JR AF Mathe, N Chen, JR TI User-centered indexing for adaptive information access SO USER MODELING AND USER-ADAPTED INTERACTION LA English DT Article; Proceedings Paper CT 4th International Conference on User Modeling (UM 94) CY 1994 CL HYANNIS, MA DE user-centered indexing; long-term adaptation; adaptive information retrieval; adaptive navigation; user feedback; shared information access ID RETRIEVAL; MODEL AB We are focusing on information access tasks characterized by large volume of hypermedia connected technical documents, a need for rapid and effective access to familiar information, and long-term interaction with evolving information. The problem for technical users is to build and maintain a personalized task-oriented model of the information to quickly access relevant information. We propose a solution which provides user-centered adaptive information retrieval and navigation. This solution supports users in customizing information access over time. It is complementary to information discovery methods which provide access to new information, since it lets users customize future access to previously found information. It relies on a technique, called Adaptive Relevance Network, which creates and maintains a complex indexing structure to represent personal user's information access maps organized by concepts. This technique is integrated within the Adaptive HyperMan system, which helps NASA Space Shuttle flight controllers organize and access large amount of information. It allows users to select and mark any part of a document as interesting, and to index that part with user-defined concepts. Users can then do subsequent retrieval of marked portions of documents. This functionality allows users to define and access personal collections of information, which are dynamically computed. The system also supports collaborative review by letting users share group access maps. The adaptive relevance network provides long-term adaptation based both on usage and on explicit user input. The indexing structure is dynamic and evolves over time. Learning and generalization support flexible retrieval of information under similar concepts. The network is geared towards more recent information access, and automatically manages its size in order to maintain rapid access when scaling up to large hypermedia space. We present results of simulated learning experiments. RP Mathe, N (reprint author), NASA, AMES RES CTR, MAIL STOP 269-2, MOFFETT FIELD, CA 94035 USA. NR 40 TC 10 Z9 10 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0924-1868 J9 USER MODEL USER-ADAP JI User Model. User-Adapt. Interact. PD JUL PY 1996 VL 6 IS 2-3 BP 225 EP 261 DI 10.1007/BF00143968 PG 37 WC Computer Science, Cybernetics SC Computer Science GA VE967 UT WOS:A1996VE96700006 ER PT J AU Amirouche, FML Tajiri, GC Valco, MJ AF Amirouche, FML Tajiri, GC Valco, MJ TI Mathematical model of a time and position variant external load on a gear tooth using the modified timoshenko beam equation SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article DE singular value decomposition; finite difference method; modified Timoshenko equation; dynamic model; gear dynamics; gear tooth testing AB A piece wise continuous closed-form dynamic model of spur gear teeth meshing, using the modified Timoshenko beam equation for a stubby cantilever beam of varying cross-sectional area, is presented. The kinematics and kinetic relationships of a shaft-driven spur gear are used to determine the force on the involute surface of the gear tooth. A convenient set of equations, used to locate this force, is presented. The co-ordinates of this force are given with respect to a gear fixed coordinate system, located at the base of the gear tooth. The governing equations of motion were then numerically solved, and dynamic simulations of the gear tooth response at different gear speeds were performed. This model was then compared with the empirical data from research performed at the NASA Lewis Research Center.(1) C1 NASA,LEWIS RES CTR,PROP DIRECTORATE,CLEVELAND,OH 44135. RP Amirouche, FML (reprint author), UNIV ILLINOIS,2027 ERF,842 W TAYLOR ST,CHICAGO,IL 60607, USA. NR 8 TC 2 Z9 2 U1 1 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD JUN 30 PY 1996 VL 39 IS 12 BP 2073 EP 2094 DI 10.1002/(SICI)1097-0207(19960630)39:12<2073::AID-NME943>3.0.CO;2-3 PG 22 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA UT384 UT WOS:A1996UT38400005 ER PT J AU Marley, MS Saumon, D Guillot, T Freedman, RS Hubbard, WB Burrows, A Lunine, JI AF Marley, MS Saumon, D Guillot, T Freedman, RS Hubbard, WB Burrows, A Lunine, JI TI Atmospheric, evolutionary, and spectral models of the brown dwarf Gliese 229 B SO SCIENCE LA English DT Article ID ABSORPTION AB Theoretical spectra and evolutionary models that span the giant planet-brown dwarf continuum have been computed based on the recent discovery of the brown dwarf Gliese 229 B. A flux enhancement in the 4- to 5-micrometer wavelength window is a universal feature from jovian planets to brown dwarfs, Model results confirm the existence of methane and water in the spectrum of Gliese 229 B and indicate that its mass is 30 to 55 jovian masses, Although these calculations focus on Gliese 229 B, they are also meant to guide future searches for extrasolar giant planets and brown dwarfs. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV ARIZONA,DEPT PHYS,TUCSON,AZ 85721. UNIV ARIZONA,DEPT ASTRON,TUCSON,AZ 85721. RP Marley, MS (reprint author), NEW MEXICO STATE UNIV,DEPT ASTRON,BOX 30001,DEPT 4500,LAS CRUCES,NM 88003, USA. RI Marley, Mark/I-4704-2013 NR 30 TC 181 Z9 181 U1 0 U2 6 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUN 28 PY 1996 VL 272 IS 5270 BP 1919 EP 1921 DI 10.1126/science.272.5270.1919 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UV294 UT WOS:A1996UV29400041 PM 8658164 ER PT J AU Hymer, WC Grindeland, RE Salada, T Cenci, R Krishnan, K Mukai, C Nagaoka, S AF Hymer, WC Grindeland, RE Salada, T Cenci, R Krishnan, K Mukai, C Nagaoka, S TI Feeding frequency affects cultured rat pituitary cells in low gravity SO JOURNAL OF BIOTECHNOLOGY LA English DT Article DE rat pituitary cell culture; microgravity ID GROWTH-HORMONE; ANTERIOR-PITUITARY; PROLACTIN; MICROGRAVITY; VARIANTS; SERUM AB In this report, we describe the results of a rat pituitary cell culture experiment done on STS-65 in which the effect of cell feeding on the release of the six anterior pituitary hormones was studied. We found complex microgravity-related interactions between the frequency of cell feeding and the quantity and quality (i.e, biological activity) of some of the six hormones released in flight. Analyses of growth hormone (GH) released from cells into culture media on different mission days using gel filtration and ion exchange chromatography yielded qualitatively similar results between ground and flight samples. Lack of cell feeding resulted in extensive cell clumping in flight (but not ground) cultures. Vigorous fibroblast growth occurred in both ground and flight cultures fed 4 times. These results are interpreted within the context of autocrine and/or paracrine feedback interactions. Finally, the payload specialist successfully prepared a fresh trypsin solution in microgravity, detached the cells from their surface and reinserted them back into the culture chamber. These cells reattached and continued to release hormone in microgravity. In summary, this experiment shows that pituitary cells are microgravity sensitive and that coupled operations routinely associated with laboratory cell culture can also be accomplished in low gravity. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NATL SPACE DEV AGCY JAPAN,IBARAKI,OSAKA 305,JAPAN. RP Hymer, WC (reprint author), PENN STATE UNIV,DEPT BIOCHEM & MOL BIOL,UNIVERSITY PK,PA 16802, USA. NR 27 TC 8 Z9 8 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1656 J9 J BIOTECHNOL JI J. Biotechnol. PD JUN 27 PY 1996 VL 47 IS 2-3 BP 289 EP 312 DI 10.1016/0168-1656(96)01373-9 PG 24 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA VF062 UT WOS:A1996VF06200024 PM 8987570 ER PT J AU Kumei, Y Shimokawa, H Katano, H Hara, E Akiyama, H Hirano, M Mukai, C Nagaoka, S Whitson, PA Sams, CF AF Kumei, Y Shimokawa, H Katano, H Hara, E Akiyama, H Hirano, M Mukai, C Nagaoka, S Whitson, PA Sams, CF TI Microgravity induces prostaglandin E(2) and interleukin-6 production in normal rat osteoblasts: Role in bone demineralization SO JOURNAL OF BIOTECHNOLOGY LA English DT Article DE bone demineralization; osteoporosis; microgravity; osteoblast; prostaglandin E2; interleukin-6 ID ARACHIDONIC-ACID METABOLISM; NEONATAL MOUSE CALVARIAE; OSTEO-SARCOMA CELLS; GROWTH-FACTOR-ALPHA; PARATHYROID-HORMONE; MESSENGER-RNA; DIFFERENTIAL REGULATION; SIGNAL TRANSDUCTION; MC3T3-E1 CELLS; SPACE-FLIGHT AB It has been suggested that microgravity alters bone metabolism. Evidence for this phenomenon includes the negative calcium balance and decreased bone density in astronauts, as well as, inhibition of bone formation in rats flown for 2 to 3 weeks. However, the specific mechanisms that modulate these changes in microgravity are unknown. The purpose of this study was to clarify the mechanism of microgravity-induced bone demineralization using normal rat osteoblasts obtained from femur marrow cultures. The osteoblasts were cultured for 5 days during a Shuttle-Spacelab flight (STS-65), After collection of the culture medium, the cellular DNA and RNA were fixed on board. Enzyme-immunoassay of the culture medium for prostaglandin E2 (PGE2) indicated that microgravity induced a 4.5- to 136-fold increase in flight samples as compared to the ground control cultures, This increase of PGE2 production was consistent with a 3.3- to 9.5-fold elevation of inducible prostaglandin G/H synthase-l? (PGHS-2) mRNA, quantitated by reverse transcription-polymerase chain reaction (RT-PCR). The mRNA induction for the constitutive isozyme PGHS-1 was less than that for PGHS-2. The interleukin-6 (IL-6) mRNA was also increased (6.4- to 9.3-fold) in microgravity as compared to the ground controls. Since PGE2. and IL-6 are both known to play a role in osteoclast formation and bone resorption, these data provide molecular mechanisms that contribute to our understanding of microgravity-induced alterations in the bone resorption process. C1 OSAKA UNIV,BIOMED RES CTR,SUITA,OSAKA 565,JAPAN. TORAY RES CTR LTD,KAMAKURA,KANAGAWA 248,JAPAN. NASDA,TSUKUBA SPACE CTR,TSUKUBA,IBARAKI 305,JAPAN. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP Kumei, Y (reprint author), TOKYO MED & DENT UNIV,FAC DENT,DEPT BIOMAT SCI,BUNKYO KU,YUSHIMA 1-5-45,TOKYO 113,JAPAN. NR 48 TC 43 Z9 46 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1656 J9 J BIOTECHNOL JI J. Biotechnol. PD JUN 27 PY 1996 VL 47 IS 2-3 BP 313 EP 324 DI 10.1016/0168-1656(96)01412-5 PG 12 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA VF062 UT WOS:A1996VF06200025 PM 8987571 ER PT J AU Seaman, GVF Snyder, RS AF Seaman, GVF Snyder, RS TI Electrophoresis in space - Foreword .2. SO JOURNAL OF BIOTECHNOLOGY LA English DT Editorial Material C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP Seaman, GVF (reprint author), EMERALD DIAGNOST INC,1720 WILLOW CREEK CIRCLE,EUGENE,OR 97402, USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1656 J9 J BIOTECHNOL JI J. Biotechnol. PD JUN 27 PY 1996 VL 47 IS 2-3 BP 335 EP 339 DI 10.1016/0168-1656(96)01530-1 PG 5 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA VF062 UT WOS:A1996VF06200027 PM 11536766 ER PT J AU Hymer, WC Salada, T Cenci, R Krishnan, K Seaman, GVF Snyder, R Matsumiya, H Nagaoka, S AF Hymer, WC Salada, T Cenci, R Krishnan, K Seaman, GVF Snyder, R Matsumiya, H Nagaoka, S TI Bioprocessing in microgravity: Applications of continuous flow electrophoresis to rat anterior pituitary particles SO JOURNAL OF BIOTECHNOLOGY LA English DT Article DE continuous flow electrophoresis; microgravity ID GROWTH-HORMONE; SEPARATION; CELLS; PROTEINS AB In this report we describe the results of a continuous flow electrophoresis (CFE) experiment done on STS-65 in which we tested the idea that intracellular growth hormone (GH) particles contained in a cell lysate prepared from cultured rat anterior pituitary cells in microgravity might have different electrophoretic mobilities from those in a synchronous ground control cell lysate. Collectively, the results suggested that CFE processing in microgravity was better than on earth; more sample could be processed/time (6 x) and more variant forms of GH molecules could be resolved as well. We had also hoped to carry out a pituitary cell CFE experiment, but failure of the hardware required that the actual cell electrophoresis trials be done on earth shortly after Shuttle landing. Data from these experiments showed that space-flown cells possessed a higher electrophoretic mobility than ground control cells, thereby offering evidence for the idea that exposure of cultured cells to microgravity can change their net surface charge-density especially when the cells are fed, Collectively, the results from this pituitary cell experiment document the advantage of using coupled cell culture and CFE techniques in the microgravity environment. C1 WESTERN BIOMED RES INST,EUGENE,OR 97402. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. BIOSYST INT INC,MINATO KU,TOKYO 106,JAPAN. NATL SPACE DEV AGCY JAPAN,IBARAKI,OSAKA 305,JAPAN. RP Hymer, WC (reprint author), PENN STATE UNIV,DEPT BIOCHEM & MOL BIOL,UNIVERSITY PK,PA 16802, USA. NR 27 TC 6 Z9 8 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1656 J9 J BIOTECHNOL JI J. Biotechnol. PD JUN 27 PY 1996 VL 47 IS 2-3 BP 353 EP 365 DI 10.1016/0168-1656(96)01406-X PG 13 WC Biotechnology & Applied Microbiology SC Biotechnology & Applied Microbiology GA VF062 UT WOS:A1996VF06200029 PM 8987574 ER PT J AU Collins, WD Valero, FPJ Flatau, PJ Lubin, D Grassl, H Pilewskie, P AF Collins, WD Valero, FPJ Flatau, PJ Lubin, D Grassl, H Pilewskie, P TI Radiative effects of convection in the tropical Pacific SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ASTRONOMICAL-ALMANACS ALGORITHM; GENERAL-CIRCULATION MODEL; SOLAR POSITION 1950-2050; SEA-SURFACE TEMPERATURE; BUDGET EXPERIMENT; SEASONAL-VARIATION; CLIMATE; ATMOSPHERE; BALANCE; OCEAN AB The radiative effects of tropical clouds at the tropopause and the ocean surface have been estimated by using in situ measurements from the Central Equatorial Pacific Experiment (CEPEX). The effect of clouds is distinguished from the radiative effects of the surrounding atmosphere by calculating the shortwave and longwave cloud forcing. These terms give the reduction in insolation and the increase in absorption of terrestrial thermal emission associated with clouds. At the tropopause the shortwave and longwave cloud forcing are nearly equal and opposite, even on daily timescales. Therefore the net effect of an ensemble of convective clouds is small compared to other radiative terms in the surface-tropospheric heat budget. This confirms the statistical cancellation of cloud forcing observed in Earth radiation budget measurements from satellites. At the surface the net effect of clouds is to reduce the radiant energy absorbed by the ocean. Under deep convective clouds the diurnally averaged reduction exceeds 150 W m(-2). The divergence of flux in the cloudy atmosphere can be estimated from the difference in cloud forcing at the surface and tropopause. The CEPEX observations show that the atmospheric cloud forcing is nearly equal and opposite to the surface forcing. Based upon the frequency of convection, the atmospheric forcing approaches 100 W m(-2) when the surface temperature is 303 K. The cloud forcing is closely related to the frequency of convective cloud systems. This relation is used in conjunction with cloud population statistics derived from satellite to calculate the change in surface cloud forcing with sea surface temperature. The net radiative cooling of the surface by clouds increases at a rate of 20 W m(-2)K(-1)during the CEPEX observing period. C1 WORLD METEOROL ORG, WORLD CLIMATE RES PROGRAMME, CH-1211 GENEVA 2, SWITZERLAND. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV CALIF SAN DIEGO, SCRIPPS INST OCEANOG, CALIF SPACE INST, LA JOLLA, CA 92093 USA. UNIV CALIF SAN DIEGO, SCRIPPS INST OCEANOG, ATMOSPHER RES LAB, LA JOLLA, CA 92093 USA. MAX PLANCK INST METEOROL, HAMBURG, GERMANY. RP Collins, WD (reprint author), UNIV CALIF SAN DIEGO, SCRIPPS INST OCEANOG, CTR CLOUDS CHEM & CLIMATE, 9500 GILMAN DR, MC 0221, LA JOLLA, CA 92093 USA. RI Collins, William/J-3147-2014; Flatau, Piotr/E-2219-2011 OI Collins, William/0000-0002-4463-9848; NR 60 TC 20 Z9 20 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 27 PY 1996 VL 101 IS D10 BP 14999 EP 15012 DI 10.1029/95JD02534 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UV948 UT WOS:A1996UV94800004 ER PT J AU Krueger, AJ Schnetzler, CC Walter, LS AF Krueger, AJ Schnetzler, CC Walter, LS TI The December 1981 eruption of Nyamuragira volcano (Zaire), and the origin of the ''mystery cloud'' of early 1982 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EL-CHICHON; MAUNA-LOA; AEROSOLS AB The ''mystery'' volcanic aerosols observed in early 1982 were produced by the eruption of Nyamuragira in eastern Zaire. Large sulfur dioxide clouds associated with this volcano were found in the total ozone mapping spectrometer data beginning on December 26, 1981, continuing into early January 1982. This fissure eruption produced 3 million tons of sulfur dioxide in clouds that rose only to the tropopause level on the basis of winds and inferred chemical loss rates (about 20%/day), which are faster than stratospheric loss rates. Two thirds of the SO2 was produced in the first 3 days of the eruption. In the 1980 this eruption was exceeded in sulfur dioxide output only by the April 1982 eruption of El Chichon. C1 UNIV MARYLAND, DEPT GEOG, COLLEGE PK, MD 20742 USA. RP Krueger, AJ (reprint author), NASA, GODDARD SPACE FLIGHT CTR, EARTH SCI DIRECTORATE, CODE 916, GREENBELT, MD 20771 USA. NR 17 TC 25 Z9 25 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 JUN 27 PY 1996 VL 101 IS D10 BP 15191 EP 15196 DI 10.1029/96JD00221 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UV948 UT WOS:A1996UV94800017 ER PT J AU Golub, MA AF Golub, MA TI Concerning apparent similarity of structures of fluoropolymer surfaces exposed to an argon plasma or argon ion beam SO LANGMUIR LA English DT Article ID TEFLON RP Golub, MA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 5 TC 3 Z9 3 U1 1 U2 5 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0743-7463 J9 LANGMUIR JI Langmuir PD JUN 26 PY 1996 VL 12 IS 13 BP 3360 EP 3361 DI 10.1021/la950792o PG 2 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA UU527 UT WOS:A1996UU52700040 PM 11540496 ER PT J AU Doyle, LR Dunham, ET Deeg, HJ Blue, JE Jenkins, JM AF Doyle, LR Dunham, ET Deeg, HJ Blue, JE Jenkins, JM TI Ground-based detectability of terrestrial and Jovian extrasolar planets: Observations of CM Draconis at Lick Observatory SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID PHOTOMETRY; SEARCH AB The detection of terrestrial-sized extrasolar planets from the ground has been thought to be virtually impossible due to atmospheric scintillation limits. However, we show that this is not the case for specially selected (but nevertheless main sequence) stars, namely small eclipsing binaries. For the smallest of these systems, CM Draconis, several months to a few years of photometric observations with 1-m-class telescopes will be sufficient to detect the transits of any short-period planets of sizes greater than or equal to 1.5 Earth radii (R(E)), using cross-correlation analysis with moderately good photometry. Somewhat larger telescopes will be needed to extend this detectability to terrestrial planets in larger eclipsing binary systems. (We arbitrarily define ''terrestrial planets'' herein as those whose disc areas are closer to that of Earth's than Neptune's i.e., less than about 2.78 R(E).) As a ''spin-off' of such observations, we will also be able to detect the presence of Jovian-mass planets without transits using the timing of the eclipse minima. Eclipse minima will drift in time as the binary system is offset by a sufficiently massive planet (i.e., one Jupiter mass) about the binary/giant-planet barycenter, causing a periodic variation in the light travel time to the observer. We present here an outline of present observations taking place at the University of California Lick Observatory using the Crossley 0.9-m telescope in collaboration with other observatories (in South Korea, Crete, France, Canary Islands, and New York) to detect or constrain the existence of terrestrial planets around main sequence eclipsing binary star systems, starting with CM Draconis. We demonstrate the applicability of photometric data to the general detection of gas giant planets via eclipse minima timings in many other small-mass eclipsing binary systems as well. C1 SRI INT, MENLO PK, CA 94025 USA. NASA, AMES RES CTR, DIV SPACE SCI, MOFFETT FIELD, CA 94035 USA. INST ASTROFIS CANARIAS, E-38200 TENERIFE, CANARY ISL, SPAIN. RP Doyle, LR (reprint author), NASA, AMES RES CTR, SETI INST, MS 245-3, MOFFETT FIELD, CA 94035 USA. NR 20 TC 9 Z9 9 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-PLANET JI J. Geophys. Res.-Planets PD JUN 25 PY 1996 VL 101 IS E6 BP 14823 EP 14829 DI 10.1029/96JE00825 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UT701 UT WOS:A1996UT70100002 PM 11539351 ER PT J AU Lestrade, JF Phillips, RB Jones, DL Preston, RA AF Lestrade, JF Phillips, RB Jones, DL Preston, RA TI Search for extrasolar planets around radio-emitting stars by very long baseline interferometry astrometry SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article AB A planet orbiting a radio-emitting star can be indirectly detected by, high-precision very long baseline interferometry (VLBI) astrometry through the reflex orbit of the star. We have observed the radio-emitting star sigma(2) CrB at 15 epochs over 7.5 years by VLBI and fitted its five astrometric parameters to the measured VLBI coordinates. The postfit coordinate residuals have an rms scatter of 0.33 milliarcsecond (mas) when all 15 epochs are used. However, when only the seven epochs at which the star was in its radio quiescent regime are used, the postfit rms drops to 0.20 mas, indicating that the radio centroid is more stable than during outbursts. The systematic errors in these VLBI astrometric observations are estimated to be 0.1 mas only. The larger rms scatter found (0.20 mas) might be caused by either a random jitter of the radio source or a planetary perturbation that is not sampled sufficiently to be recognized by visual inspection of the postfit position residuals. This will be tested by more frequent VLBI observations of this star in the future. Finally, the theoretical (signal-to-noise ratio-limited) astrometric precision of VLBI observations of radio-emitting stars is similar to 10 mu arc sec and corresponds to an interesting limit to search for giant planets around stars up to 200 pc and even for an Earth-like planet but around the nearest radio-emitting star UV Ceti. C1 CALTECH,JET PROP LAB,PASADENA,CA. MIT,HAYSTACK OBSERV,WESTFORD,MA 01886. RP Lestrade, JF (reprint author), OBSERV MEUDON PARIS,CNRS,F-92195 MEUDON,FRANCE. NR 9 TC 4 Z9 4 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUN 25 PY 1996 VL 101 IS E6 BP 14837 EP 14841 DI 10.1029/96JE00667 PG 5 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA UT701 UT WOS:A1996UT70100004 ER PT J AU Fukazawa, Y Makishima, K Matsushita, K Yamasaki, N Ohashi, T Mushotzky, RF Sakima, Y Tsusaka, Y Yamashita, K AF Fukazawa, Y Makishima, K Matsushita, K Yamasaki, N Ohashi, T Mushotzky, RF Sakima, Y Tsusaka, Y Yamashita, K TI Metal abundance of an X-ray emitting gas in two groups of galaxies: The NGC 5044 group and HCG 51 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE galaxies, abundances; galaxies, clusters of; galaxies, individual (NGC 5044, HCG 51); galaxies, intergalactic medium ID COMPACT-GROUPS; DARK MATTER; HOT PLASMA; CLUSTERS; EMISSION AB We observed two groups of galaxies, the NGC 5044 group (WP 23) and Hickson's compact group HCG 51, with ASCA. We detected an extended bright soft X-ray emission, which indicates the existence of large amounts of a hot X-ray emitting gas in both targets. The temperature of the hot gas is similar to 1 keV for both objects, which is equivalent to their galaxy velocity dispersion. The metal abundance of the gas is 0.3-0.5 solar value for both objects, which is similar to that of rich clusters of galaxies. The Si to Fe abundance ratio is smaller than that of rich clusters of galaxies, although the iron abundances determined by the Fe-L lines are somewhat uncertain. The X-ray luminosities in the 0.5-10 keV band are 1x10(43) erg s(-1) and 5x10(42) erg s(-1) for the NGC 5044 group and HCG 51, respectively, which are higher by an order of magnitude than those of X-ray bright elliptical galaxies. This makes HCG 51 one of the most X-ray luminous compact groups. Both objects have a total gravitating mass of M(total) similar to 2.0 x 10(13) M., and a gas mass and a galaxy mass of M(gas) similar to M(galaxy) similar to 1.5 x 10(12) M.. The ratios among these mass components are M(gas)/M(galaxy) similar to 1 and (M(gas)+M(galaxy))/M/total similar to 0.2 within similar to 350 kpc for both objects. The latter is similar to previous ROSAT results for many groups of galaxies, while the former is larger than the average value of the ROSAT-observed groups. Moreover, the metal abundances of the present two groups are significantly higher than those of the NGC 2300 group and HCG 62, and are comparable to those of clusters. These suggest that the hot-gas mass and metal abundances can scatter widely among groups, compared to the small variance found among rich clusters. C1 TOKYO METROPOLITAN UNIV, DEPT PHYS, FAC SCI, HACHIOJI, TOKYO 19203, JAPAN. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. NAGOYA UNIV, DEPT PHYS, FAC SCI, CHIKUSA KU, NAGOYA, AICHI 46401, JAPAN. INST MOLEC SCI, OKAZAKI, AICHI 444, JAPAN. RP UNIV TOKYO, DEPT PHYS, SCH SCI, BUNKYO KU, 7-3-1 HONGO, TOKYO 113, JAPAN. RI Yamasaki, Noriko/C-2252-2008 NR 49 TC 34 Z9 34 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 JUN 25 PY 1996 VL 48 IS 3 BP 395 EP 407 DI 10.1093/pasj/48.3.395 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UU692 UT WOS:A1996UU69200004 ER PT J AU Maeda, Y Koyama, K Sakano, M Takeshima, T Yamauchi, S AF Maeda, Y Koyama, K Sakano, M Takeshima, T Yamauchi, S TI A New Eclipsing X-Ray Burster near the Galactic Center: A Quiescent State of the Old Transient A1742-289 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE binaries, eclipsing; interstellar, dust; stars, individual (A1742-289); X-rays, bursts AB With ASCA, we found highly absorbed X-rays from the position of the bright transient source A1742-289 with a variable flux ranging from 8 x 10(-12) to 4 x 10(-11) erg s(-1) cm(-2) in the 3-10 keV band. We discovered an X-ray burst and eclipses from A1742-289, establishing that A1742-289 is an eclipsing low-mass X-ray binary. Using the black-body radius during an X-ray burst, we estimated the distance of A1742-289 to be about 10 kpc, or near to the galactic center. The burst peak flux was then found below the Eddington limit of a neutron stay. Excess soft X-rays during the eclipse were detected, which are interpreted to be scattering by interstellar dust-grains. Since A1742-289 was found to be an X-ray emitter, even in the quiescent state with a moderate but variable flux, and since A1742-289 is lying only 1'.3 from the galactic center, previously reported X-ray fluxes of the galactic center (Sgr A*) with non-imaging instruments might have suffered due to possible contamination of A1742-289. C1 NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. IWATE UNIV, FAC HUMANITIES & SOCIAL SCI, MORIOKA, IWATE 020, JAPAN. RP KYOTO UNIV, FAC SCI, DEPT PHYS, SAKYO KU, KYOTO 60601, JAPAN. NR 23 TC 48 Z9 48 U1 0 U2 1 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 JUN 25 PY 1996 VL 48 IS 3 BP 417 EP + DI 10.1093/pasj/48.3.417 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UU692 UT WOS:A1996UU69200006 ER PT J AU Ebisawa, K Day, CSR Kallman, TR Nagase, F Kotani, T Kawashima, K Kitamoto, S Woo, JW AF Ebisawa, K Day, CSR Kallman, TR Nagase, F Kotani, T Kawashima, K Kitamoto, S Woo, JW TI X-ray spectroscopy of Centaurus X-3 with ASCA over an eclipse SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE binaries, eclipsing; pulsars; stars, individual (Centaurus X-3); stars, neutron; X-rays, sources ID K LINE EMISSION; IRON LINE; CIRCUMSTELLAR MATTER; STELLAR WINDS; VELA X-1; BINARIES; GX301-2; PULSARS; MODELS; SYSTEM AB The X-ray binary pulsar Cen X-3 was observed with the ASCA satellite over an entire binary eclipse. With unprecedented energy resolution at the iron K-energy band (FWHM similar to 2%), three iron emission lines at 6.4 keV, 6.7 keV, and 6.97 keV were clearly resolved. At lower energies, lines from hydrogenic ions of Ne, Mg, Si, and S were also observed. Spectral variations over the eclipse were studied, in particular variations of the iron emission lines. Although the intensity of the 6.4 keV line, which is due to fluorescence from low ionized iron, decreased about one order of magnitude during the eclipse, the intensity drop of the 6.7 and 6.97 keV lines, which are respectively from Fe XXV and Fe XXVI, was at most a factor of three. This, confirming the conjecture by Nagase et al. (1992, AAA56.117.175), indicates that the 6.4 keV fluorescent line is emitted from the region close to the neutron star while the highly photoionized plasma which emits 6.7 and 6.97 keV lines is more extended than the size of the companion star (similar to 12 R.). The 6.4 keV line equivalent-width did not show a large variation over the eclipse, and was 75-145 eV. The dense Alfven shell or an optically thick accretion disk is a likely candidate for reprocessing the fluorescent iron line. From the intensity ratio of the 6.7 and 6.97 keV lines during the eclipse, the ionization parameter of the photoionized plasma is estimated as xi similar to 10(3.4). The size and the density of the plasma are estimated as similar to 16 R. and similar to 1.3 X 10(11) cm(-3), respectively. It is suggested that a lower ionization state is dominated in the pre-eclipse phase, since the 6.7 and 6.97 keV lines were not clearly seen and other K-lines from lighter elements were strong. C1 INST SPACE & ASTRONAUT SCI, SAGAMIHARA, KANAGAWA 229, JAPAN. OSAKA UNIV, FAC SCI, DEPT EARTH & SPACE SCI, TOYONAKA, OSAKA 560, JAPAN. MIT, CTR SPACE RES, CAMBRIDGE, MA 02139 USA. UNIV SPACE RES ASSOC, COLUMBIA, MD USA. RP NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, CODE 6602, GREENBELT, MD 20771 USA. NR 32 TC 48 Z9 48 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 JUN 25 PY 1996 VL 48 IS 3 BP 425 EP 440 DI 10.1093/pasj/48.3.425 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UU692 UT WOS:A1996UU69200007 ER PT J AU Martin, BG Lee, HP Jones, EW AF Martin, BG Lee, HP Jones, EW TI GaAs/AlAs/Si heterostructures for blocking dark current injection in impurity-band-conduction photodetectors (vol 68, pg 1250, 1996) SO APPLIED PHYSICS LETTERS LA English DT Correction, Addition C1 UNIV CALIF IRVINE,DEPT ELECT & COMP ENGN,IRVINE,CA 92717. JET PROP LAB,PASADENA,CA 91109. RP Martin, BG (reprint author), ANAL CONSULTANTS,LAKE FOREST,CA 92630, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUN 24 PY 1996 VL 68 IS 26 BP 3832 EP 3832 DI 10.1063/1.116793 PG 1 WC Physics, Applied SC Physics GA UT481 UT WOS:A1996UT48100053 ER PT J AU Ma, Q Tipping, RH Boulet, C AF Ma, Q Tipping, RH Boulet, C TI The frequency detuning and band-average approximations in a far-wing line shape theory satisfying detailed balance SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID INFRARED-ABSORPTION SPECTRA; WATER CONTINUUM ABSORPTION; ROTATIONAL BANDS; CO2 AB We develop the basic formalism of a far-wing line shape theory that satisfies the detailed balance principle. For molecular systems of interest, e.g., CO2-Ar at room temperature or higher, there are many individual vibration-rotational lines in a given band and many bands in the spectrum. In such cases, one must make additional approximations in order to carry out accurate calculations of the absorption coefficient using a reasonable amount of computer time. In the present paper, we discuss two such simplifications: the frequency detuning approximation of the line-coupling functions and the band-average approximation. We then apply the theory to a calculation of the far-wing absorption of the nu(3) band of CO2 perturbed by Ar, successively including the effects of more lines in the calculations by increasing J(max) from 40 to 108, From the results of this work, we find that the frequency detuning approximation is good only for frequencies of interest far from the band center. In addition, we find that contrary to previous assertions of the adequacy of the first-order band-average approximation, the higher-order terms are significant. To a good approximation these can be incorporated by introducing a frequency shift in the first-order results so that extensive additional calculations are not required. (C) 1996 American Institute of Physics. C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. UNIV ALABAMA,DEPT PHYS & ASTRON,TUSCALOOSA,AL 35487. UNIV PARIS 11,CNRS UPR136,LAB PHYS MOL & APPLICAT,F-91405 ORSAY,FRANCE. RP Ma, Q (reprint author), COLUMBIA UNIV,DEPT APPL PHYS,NEW YORK,NY 10025, USA. NR 13 TC 11 Z9 12 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUN 22 PY 1996 VL 104 IS 24 BP 9678 EP 9688 DI 10.1063/1.471730 PG 11 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UR692 UT WOS:A1996UR69200002 ER PT J AU Payne, WA Monks, PS Nesbitt, FL Stief, LJ AF Payne, WA Monks, PS Nesbitt, FL Stief, LJ TI The reaction between N(S-4) and C2H3: Rate constant and primary reaction channels SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID ETHYLENE; ATOMS; CHEMISTRY; ACETYLENE; BEARING; RATIOS AB The rate constant and the product branching ratios have been determined at T=298 K for the reaction between ground state atomic nitrogen (S-4) and the vinyl radical (C2H3) at a nominal pressure of 1 Torr He. The kinetic technique employed was discharge-flow coupled to a collision-free sampling mass spectrometer. The rate constant was determined by monitoring the decay of the vinyl radical in the presence of excess [N], yielding a value for k(N+C2H3) of (7.7+/-2.9) x 10(-11) cm(3) molecule(-1) s(-1). Three primary reaction channels have been experimentally observed: N+C2H3+C2H2+NH (1a), C2H2N+H (1b), and C2H3N (1c). The lowest energy isomers of the C2H2N radical and the C2H3N adduct molecule are CH2CN and CH3CN, respectively and their identification as products of the reaction is consistent with experimental results. Contributions from the higher energy isomers CH2NC or cyc-C2H2N in channel (1b) and CH3NC or H2C=C=NH in channel (1c) are not consistent with the experimental results and can be ruled out. Contribution from other higher energy isomers such as the radicals HC-CH=N, HC=C=NH and H2C=C=N in channel (1b) and the adduct species vinyl nitrene and 2H-azirine in channel (1c) cannot be ruled out in the absence of knowledge of heats of formation of the radical species and ionization energies for both the radical and adduct species. The following branching ratios were determined at T=298 K: Gamma(1a) = 0.16, Gamma(1c)=0.04. No other potential products were detected. It can therefore be inferred that channel (1b) accounts for most if not all of the remaining products, i.e., Gamma(1b) = 0.80. The magnitude of the rate constant and the nature of the observed products for N+C2H3 are compared with those for the reactions N+CH3 and N+C2H5. The formation of the adduct molecule is considered in terms of initial formation of vinyl nitrene or 2H-azirine followed by a series of ring openings, ring closings, and an H atom transfer to yield the lowest energy isomer acetonitrile, CH3CN. The possible role of the N+C2H3 reaction in the atmospheric chemistry of Titan, Neptune, and Triton is briefly considered. (C) 1996 American Institute of Physics. C1 COPPIN STATE COLL,BALTIMORE,MD 21216. RP Payne, WA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Monks, Paul/H-6468-2016 OI Monks, Paul/0000-0001-9984-4390 NR 35 TC 24 Z9 24 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUN 22 PY 1996 VL 104 IS 24 BP 9808 EP 9815 DI 10.1063/1.471740 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA UR692 UT WOS:A1996UR69200015 ER PT J AU Volk, CM Elkins, JW Fahey, DW Salawitch, RJ Dutton, GS Gilligan, JM Proffitt, MH Loewenstein, M Podolske, JR Minschwaner, K Margitan, JJ Chan, KR AF Volk, CM Elkins, JW Fahey, DW Salawitch, RJ Dutton, GS Gilligan, JM Proffitt, MH Loewenstein, M Podolske, JR Minschwaner, K Margitan, JJ Chan, KR TI Quantifying transport between the tropical and mid-latitude lower stratosphere SO SCIENCE LA English DT Article ID MOUNT-PINATUBO; INSITU MEASUREMENTS; OZONE DEPLETION; AEROSOL; N2O; CONSTITUENTS; SIMULATIONS; ABSORPTION; CF2CL2; CFCL3 AB Airborne in situ observations of molecules with a wide range of lifetimes (methane, nitrous oxide, reactive nitrogen, ozone, chlorinated halocarbons, and halon-1211), used in a tropical tracer model, show that mid-latitude air is entrained into the tropical lower stratosphere within about 13.5 months; transport is faster in the reverse direction, Because exchange with the tropics is slower than global photochemical models generally assume, ozone at mid-latitudes appears to be more sensitive to elevated levels of industrial chlorine than is currently predicted, Nevertheless, about 45 percent of air in the tropical ascent region at 21 kilometers is of mid-latitude origin, implying that emissions from supersonic aircraft could reach the middle stratosphere. C1 UNIV COLORADO,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. NOAA,AERON LAB,BOULDER,CO 80303. CALTECH,JET PROP LAB,PASADENA,CA 91109. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NEW MEXICO INST MIN & TECHNOL,DEPT PHYS,SOCORRO,NM 87801. RP Volk, CM (reprint author), NOAA,CLIMATE MONITORING & DIAGNOST LAB,BOULDER,CO 80303, USA. RI Salawitch, Ross/B-4605-2009; Gilligan, Jonathan/I-8938-2014; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Gilligan, Jonathan/0000-0003-1375-6686; Fahey, David/0000-0003-1720-0634 NR 50 TC 129 Z9 129 U1 0 U2 11 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUN 21 PY 1996 VL 272 IS 5269 BP 1763 EP 1768 DI 10.1126/science.272.5269.1763 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UT110 UT WOS:A1996UT11000035 ER PT J AU Ferrarese, L Freedman, WL Hill, RJ Saha, A Madore, BF Kennicutt, RC Stetson, PB Ford, HC Graham, JA Hoessel, JG Han, MS Huchra, J Hughes, SM Illingworth, GD Kelson, D Mould, JR Phelps, R Silbermann, NA Sakai, S Turner, A Harding, P Bresolin, F AF Ferrarese, L Freedman, WL Hill, RJ Saha, A Madore, BF Kennicutt, RC Stetson, PB Ford, HC Graham, JA Hoessel, JG Han, MS Huchra, J Hughes, SM Illingworth, GD Kelson, D Mould, JR Phelps, R Silbermann, NA Sakai, S Turner, A Harding, P Bresolin, F TI The extragalactic distance scale key project .4. The discovery of Cepheids and a new distance to M100 using the Hubble space telescope SO ASTROPHYSICAL JOURNAL LA English DT Article DE Cepheids; galaxies, distances and redshifts; galaxies, individual (M100) ID VIRGO CLUSTER; CCD PHOTOMETRY; GALAXIES; CLOUD; STARS AB We report on observations of Cepheids in the Virgo spiral galaxy M100, based on data obtained with the Wide Field and Planetary Camera 2 (WFPC2) on board the Hubble Space Telescope (HST). The observations are part of the HST Key Project on the Extragalactic Distance Scale, which aims to provide a measurement of the Hubble constant H-0 with 10% accuracy. A total of 12 epochs were obtained using the F555W filter (transformed to Johnson V), and 4 epochs using the F814W filter (transformed to Cousins I). Photometry on the data was performed using two independent packages, DoPHOT and DAOPHOT II/ALLFRAME; a total of 52 Cepheids, with periods ranging from about 10 to 70 days, were identified based on both sets of photometry. We have fitted V and I period-luminosity relations and derived apparent V and I distance moduli assuming a Large Magellanic Cloud distance modulus and mean color excess of mu(LMC) = 18.50 +/- 0.10 mag and E(B - V) = 0.10 mag, respectively. Using the extinction law given by Cardelli, Clayton, & Mathis, and adopting our most recent WFPC2 (''long-exposure'') zero-point calibration, we obtain a true distance modulus for M100 of mu(0) = 30.04 +/- 0.17 mag, corresponding to a distance d = 16.1 +/- 1.3 Mpc, and a total (Galactic plus internal) mean color excess E(B - V) = 0.10 +/- 0.06 mag. When compared with the preliminary distance of 17.1 +/- 1.8 Mpc derived by Freedman et al. from the same set of data, the results presented here benefit from a larger sample size, refinements in the zero-point calibration, and improvements in the software packages used for the photometry. The two results agree to within their quoted errors. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. CARNEGIE INST WASHINGTON OBSERV,PASADENA,CA 91101. CALTECH,PASADENA,CA 91125. NASA,IPAC EXTRAGALACT DATABASE,PASADENA,CA 91125. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. DOMINION ASTROPHYS OBSERV,VICTORIA,BC V8X 4M6,CANADA. UNIV WISCONSIN,MADISON,WI 53706. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. ROYAL GREENWICH OBSERV,CAMBRIDGE CB3 0HA,ENGLAND. UNIV CALIF SANTA CRUZ,LICK OBSERV,SANTA CRUZ,CA 95064. AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,INST ADV STUDIES,WESTON,ACT 2611,AUSTRALIA. RP Ferrarese, L (reprint author), JOHNS HOPKINS UNIV,BALTIMORE,MD 21218, USA. NR 53 TC 177 Z9 177 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 568 EP & DI 10.1086/177347 PN 1 PG 49 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400005 ER PT J AU Stecker, FW Salamon, MH AF Stecker, FW Salamon, MH TI The gamma-ray background from blazars: A new look SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, active; gamma rays, theory; quasars, general ID RADIATION; 3C-279 AB We present the results of a new model calculation of the gamma-ray background produced by unresolved blazars, using the second EGRET catalog and taking account of flaring. These results are compared to the preliminary gamma-ray background spectrum reported recently by the EGRET team. We find that blazars can account for the entire extragalactic gamma-ray background observed by EGRET. In addition, the EGRET spectrum shows some evidence of a signature for the blazar background, a concavity in the spectrum first pointed out in our earlier paper. C1 UNIV UTAH,DEPT PHYS,HIGH ENERGY ASTROPHYS INST,SALT LAKE CITY,UT 84112. RP Stecker, FW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Stecker, Floyd/D-3169-2012 NR 29 TC 186 Z9 187 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 600 EP 605 DI 10.1086/177348 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400006 ER PT J AU Pendleton, GN Mallozzi, RS Paciesas, WS Briggs, MS Preece, RD Koshut, TM Horack, JM Meegan, CA Fishman, GJ Hakkila, J Kouveliotou, C AF Pendleton, GN Mallozzi, RS Paciesas, WS Briggs, MS Preece, RD Koshut, TM Horack, JM Meegan, CA Fishman, GJ Hakkila, J Kouveliotou, C TI The intensity distribution for gamma-ray bursts observed with BATSE SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology, observations; gamma rays, bursts AB The intensity distributions of gamma-ray bursts observed by BATSE from 1991 April 19 to 1994 September 19 are presented. For this data set, [V/V-max] is 0.329 +/- 0.011, which is 15.5 sigma away from the value of 0.5 expected for a homogeneous distribution. Standard cosmological model parameters are obtained by fitting the differentially binned peak flux distribution expressed in units of photons cm(-2) s(-1) in the energy range 50-300 keV. The value of z calculated for a peak flux of 1 photon cm(-2) s(-1) is 0.8 +/- 0.33. The procedures used to produce the peak flux data and C-p/C-lim data are presented. The differences between the two representations of burst intensity are emphasized so that researchers can determine which type of data is most appropriate for their studies. The sky sensitivity correction as a function of intensity for the peak flux data is also described. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. MANKATO STATE UNIV, DEPT PHYS & ASTRON, MANKATO, MN 56002 USA. UNIV SPACE RES ASSOC, WASHINGTON, DC USA. RP Pendleton, GN (reprint author), UNIV ALABAMA, DEPT PHYS, HUNTSVILLE, AL 35899 USA. RI Horack, John/J-6670-2016; OI Preece, Robert/0000-0003-1626-7335 NR 12 TC 44 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 JUN 20 PY 1996 VL 464 IS 2 BP 606 EP 615 DI 10.1086/177349 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400007 ER PT J AU Sreekumar, P Bertsch, DL Dingus, BL Esposito, JA Fichtel, CE Fierro, J Hartman, RC Hunter, SD Kanbach, G Kniffen, DA Lin, YC MayerHasselwander, HA Mattox, JR Michelson, PF vonMontigny, C Mukherjee, R Nolan, PL Schneid, E Thompson, DJ Willis, TD AF Sreekumar, P Bertsch, DL Dingus, BL Esposito, JA Fichtel, CE Fierro, J Hartman, RC Hunter, SD Kanbach, G Kniffen, DA Lin, YC MayerHasselwander, HA Mattox, JR Michelson, PF vonMontigny, C Mukherjee, R Nolan, PL Schneid, E Thompson, DJ Willis, TD TI EGRET observations of the north Galactic pole region SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, clusters, individual (Coma); gamma rays, observations; intergalactic medium; surveys ID GAMMA-RAY EMISSION; X-RAY; TIME VARIABILITY; COSMIC-RAY; RADIO; RADIATION; TELESCOPE; ELECTRONS; 3C-279; GALAXY AB The EGRET instrument aboard the Compton Gamma Rag, Observatory (CGRO) has carried out the first ever all-sky survey in high-energy gamma rays. Initial analysis of the region near the north Galactic pole showed the presence of several previously undetected point sources, many of which exhibit time variability in the observed emission. A more detailed analysis using all observations during phases I and II of the CGRO observing plan shows a total of 21 point sources detected above a 4 sigma significance level in the region of the sky with b > 40 degrees. Results on source location, possible identification, energy spectrum, and time variability are discussed. Of the 21 sources, 17 are identified as belonging to the blazar class of active galactic nuclei. They include 0917+449, 1127-145, and 1222+216, which are positionally coincident with previous unidentified EGRET sources. The four remaining unidentified sources appear to have no known counterparts. No evidence is found for high-energy gamma-ray emission from M82, M87, or the Coma Cluster. The upper limit from Coma is used to derive a lower limit of 0.4 mu G on the intracluster magnetic field. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. STANFORD UNIV,WW HANSEN LABS PHYS,STANFORD,CA 94305. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. UNIV MARYLAND,COLLEGE PK,MD 20742. NORTHROP GRUMMAN CORP,BETHPAGE,NY 11714. RP Sreekumar, P (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 660,GREENBELT,MD 20771, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; OI Thompson, David/0000-0001-5217-9135; Dingus, Brenda/0000-0001-8451-7450 NR 70 TC 109 Z9 110 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 628 EP 640 DI 10.1086/177352 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400010 ER PT J AU Chakrabarti, SK AF Chakrabarti, SK TI Grand unification of solutions of accretion and winds around black holes and neutron stars SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; hydrodynamics; shock waves; stars, mass loss; stars, neutron ID EMERGENT RADIATION SPECTRUM; TRANSONIC DISK ACCRETION; RANKINE-HUGONIOT SHOCKS; HYBRID MODEL FLOWS; SPHERICAL ACCRETION; STANDING SHOCKS; THICK ACCRETION; ROTATING WINDS; BINARY-SYSTEMS; INSTABILITY AB We provide the complete set of global solutions of viscous transonic hows (VTFs) around black holes and neutron stars. These solutions describe the optically thick and optically thin hows from the horizon of the black hole or from the neutron star's surface to the location where the flow joins with a Keplerian disk. We study the nature of the multiple sonic points as functions of advection, rotation, viscosity, heating, and cooling. Stable shock waves, which join two transonic solutions, are found to be present in a large region of the parameter space. We classify the solutions in terms of whether or not the flow can have a standing shock wave. We find no new topology of solutions other than what was observed in our previous studies of isothermal VTFs. We particularly stress the importance of the boundary conditions and argue that we have the most complete solution of accretion and winds around black holes and neutron stars. C1 TATA INST FUNDAMENTAL RES,BOMBAY 400005,MAHARASHTRA,INDIA. RP Chakrabarti, SK (reprint author), GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 76 TC 117 Z9 118 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 664 EP 683 DI 10.1086/177354 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400012 ER PT J AU Hough, DH Zensus, JA Porcas, RW AF Hough, DH Zensus, JA Porcas, RW TI Evidence for acceleration and nonradial motion of parsec-scale jet components in the lobe-dominated superluminal quasar 3C 263 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies, jets; galaxies, nuclei; quasars, individual (3C 263); radio continuum, galaxies ID RADIO-SOURCES; EXTENDED QUASARS; STATISTICS AB We report evidence for accelerated and nonradial motion of parsec-scale jet components in the nucleus of the lobe-dominated quasar 3C 263. New VLBI maps at 10.7 GHz confirm that the jet component J1 moves with superluminal speed. While the initial apparent transverse velocity of J1 was v(app) similar to 1.2 h(-1) c (H-o = 100 h km s(-1) Mpc(-1), q(o) = 0.5), the new maps indicate an average v(app) similar to 2.2 h(-1) c over a span of similar to 8 yr. This suggests the possibility of component acceleration, which could most simply be accounted for in a relativistic jet model that allows time variations in the Lorentz factor. The new maps also reveal a second jet component J2 that has moved along a significantly different radial direction than J1 with respect to the core component C. Component J2 shows a marginal change in direction that may be bringing it into alignment with the path of J1. We estimate v(app) similar to 0.7 h(-1) c for J2. We also present a new 8.4 GHz VLBI map that will enable us to continue monitoring 3C 263 with the VLBA. We relate our results to other properties of 3C 263 and discuss their implications for relativistic jet models and ''unified schemes.'' We conclude that the low superluminal speeds in many lobe-dominated quasars, together with the suggested mildly accelerated and nonradial motion exhibited by 3C 263, are consistent with unification of core- and lobe-dominated quasars. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. MAX PLANCK INST RADIOASTRON,D-53121 BONN,GERMANY. RP Hough, DH (reprint author), TRINITY UNIV,DEPT PHYS,SAN ANTONIO,TX 78212, USA. NR 40 TC 11 Z9 11 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 715 EP 723 DI 10.1086/177358 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400016 ER PT J AU Magnier, EA Chu, YH Points, SD Hwang, U Smith, RC AF Magnier, EA Chu, YH Points, SD Hwang, U Smith, RC TI X-rays from superbubbles in the large magellanic cloud .4. The blowout structure of N44 SO ASTROPHYSICAL JOURNAL LA English DT Article DE H II regions; ISM, bubbles; ISM, individual (LMC N44); ISM, jets and outflows; magellanic clouds; X-rays, ISM ID ASSOCIATIONS; COMPLEX AB We have used optical echelle spectra along with ROSAT and ASCA X-ray spectra to test the hypothesis that the southern portion of the N44 X-ray bright region is the result of a blowout structure. Three pieces of evidence now support this conclusion. First, the filamentary optical morphology corresponding with the location of the X-ray bright South Bar suggests the blowout description (Chu et al. 1993). Second, optical echelle spectra show evidence of high-velocity (approximate to 90 km s(-1)) gas in the region of the blowout. Third, X-ray spectral fits show a lower temperature for the South Bar than the main superbubble region of shell 1. Such a blowout can affect the evolution of the superbubble and explain some of the discrepancy discussed by Oey & Massey (1995) between the observed shell diameter and the diameter predicted on the basis of the stellar content and the pressure-driven bubble model of Weaver et al. (1977). C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109. RP Magnier, EA (reprint author), UNIV ILLINOIS,DEPT ASTRON,1002 W GREEN ST,URBANA,IL 61801, USA. NR 22 TC 30 Z9 30 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 829 EP 835 DI 10.1086/177368 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400026 ER PT J AU Feibelman, WA AF Feibelman, WA TI The IUE spectrum of the unusual Wolf-Rayet pg 1159-type star Sanduleak 3 SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars, individual (Sanduleak 3); stars, Wolf-Rayet; ultraviolet, stars ID PLANETARY-NEBULAE; EMISSION; SPECTROPHOTOMETRY AB Archival and new IUE spectra are presented for the very hot WC O VI star Sand 3 (=WR 72), covering the wavelength range 1170-3200 Angstrom Emission-line fluxes were measured and terminal wind velocities were determined from the P Cyg N V and C IV doublets. Sand 3 is known to show some of the highest excitation stellar lines in the optical region, and the UV data confirm this by displaying lines of C IV, C V, O VI, He II, and probably O VIII and Ne VII. Nebular features include O III] lambda lambda 1661, 1667 and C III] lambda lambda 1907, 1909; [Ne V] lambda lambda 1575, 1722, 2250, 2974; [Ne IV] lambda lambda 1601, 2424; [Ar IV] lambda lambda 2854, 2869; adn [Mg V] lambda lambda`294, 1324, 2783. Based on IUE, optical, and IRAS data, a model is proposed that suggests four distinct emission zones for Sand 3: A photospheric region, a chromosphere or corona, a nebular region, and a dust shell. Comparisons of Sand 3 are made with the ''O VI sequence'' nuclei of NGC 2371-2, NGC 5189, NGC 5315, NGC 6905, and He 2-99. Although not definitely seen in Sand 3, O VII is detected for the first time in IUE spectra of the central stars of NGC 5189 and NGC 2371-2. RP Feibelman, WA (reprint author), NASA,GODDARD LAB ASTRON & SOLAR PHYS,CODE 681,GREENBELT,MD 20771, USA. NR 45 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 910 EP 923 DI 10.1086/177379 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400037 ER PT J AU Aschwanden, MJ Schwartz, RA AF Aschwanden, MJ Schwartz, RA TI The inversion of electron time-of-flight distances from hard X-ray time delay measurements SO ASTROPHYSICAL JOURNAL LA English DT Article DE radiation mechanisms, nonthermal; radiative transfer; Sun, flares; Sun, X-rays, gamma rays ID SOLAR-FLARES; BURSTS; TARGET; RADIO; BEAM AB The electron time-of-fhght distance I between the acceleration site and the chromosphere can be measured during solar flares from energy-dependent hard X-ray (HXR) time delays tau(epsilon), based on the applicability of the thick-target model. The determination of the path length I represents an inversion problem because the time-dependent electron injection spectrum at the acceleration site, N(E, t, x = 0), is retarded by the propagation time t(prop)(E) = l/v(E) at the thick-target site, i.e., N(E, t, x = l) = N[E, t - t(prop)(E), x = 0], and has to be convolved with the bremsstrahlung cross section sigma(epsilon, E) and the instrumental detector response function R(i)(epsilon) to reproduce the observed HXR time profiles I(epsilon(i), t) (indifferent detector channels i), from which the time delay differences tau(epsilon(i)) - tau(epsilon(j)) can be measured. In this study, we solve this inversion problem by numerical forward integration of time-dependent electron injection spectra N(E, t) with Gaussian pulse shapes to obtain the convolved time-dependent HXR spectra I(epsilon, t), using specific detector response functions from the Burst and Transient Source Experiment/Compton Gamma Ray Observatory and the Hard X-Ray Burst Spectrometer/Solar Maximum Mission. We find that the timing of HXR pulses can be accurately represented with the (monoenergetic) photon energy epsilon(i) that corresponds to the median of the channel count spectra C-i(epsilon) = I(epsilon)R(i)(epsilon). We compute numerical conversion factors q(E)(epsilon, gamma, E(0)) that permit the conversion of the timing of photon energies epsilon(i)(t) (for a power-law spectrum with slope gamma and upper cutoff energy E,) into electron energies E(i)(t)= q(E) epsilon(t), from which kinematic parameters can be fitted to determine the electron time-of-flight path length E. We test the inversion procedure with numeric simulations and demonstrate that the inversion is accurate within sigma(i)/l less than or similar to 1% for noise-free data. This inversion procedure is applied to the Masuda flare (in this volume) to localize the electron acceleration region. C1 NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,LASP,GREENBELT,MD 20771. RP Aschwanden, MJ (reprint author), UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742, USA. NR 19 TC 22 Z9 22 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 974 EP 984 DI 10.1086/177385 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400043 ER PT J AU Aschwanden, MJ Hudson, H Kosugi, T Schwartz, RA AF Aschwanden, MJ Hudson, H Kosugi, T Schwartz, RA TI Electron time-of-flight measurements during the Masuda flare, 1992 January 13 SO ASTROPHYSICAL JOURNAL LA English DT Article DE particle acceleration; radiation mechanisms, nonthermal; Sun, corona; Sun, flares; Sun, X-ray radiation, gamma rays ID X-RAY TELESCOPE; SOLAR-A MISSION; ACCELERATION PROCESSES; BURSTS; STABILITY; TARGET; PHASE; BEAM AB The solar flare of 1992 January 13, 1729 UT, has become famous because Masuda's discovery of a hard X-ray loop-top source (Masuda 1994). Here we analyze energy-dependent time delays occurring in 30-120 keV hard X-ray (HXR) emission during this flare, observed by BATSE on board the Compton Gamma Ray Observatory with a time resolution of 64 ms. The purpose of this study is to reconstruct the kinematics of HXR-producing electrons from energy-dependent HXR delays, and to relate the inferred time-of-flight distance to the spatial geometry of the flare loop, as observed by SXT and HXT on board Yohkoh. The findings are the following: 1. The HXR flux can be decomposed into a sequence of pulses with approximate to 2-3 s duration and into a smoothly varying envelope that accounts for 90% of the greater than or equal to 30 keV flux. Cross-correlating the pulses between five different energy channels in the 30-120 keV range, we find that the HXR pulses are delayed (tau(p) = 40-220 ms) at the lower energies with respect to the higher energies. For the HXR envelopes, we find much larger delays (-tau(E) = 2.1-6.6 s) of opposite sign. 2. We fit kinematic models that quantify electron acceleration and propagation times to the observed HXR timing, for small-scale and large-scale accelerating fields, in semicircular and cusplike flare loop geometries. We find that the acceleration site is most likely located in an altitude of h = 44,000 +/- 6000 km, in the cusp region above the SXR-emitting flare loop (h = 12,500 km), and also significantly above Masuda's coronal HXR source (h = 22,100 km). This finding offers an interpretation of Masuda's HXR source in terms of nonthermal bremsstrahlung by electrons partially confined in the cusp region either by magnetic mirroring or by wave turbulence in the reconnection outflow. 3. The delay of the smoothly varying HXR flux is found to be consistent with trapping time differences in terms of collisional deflection, based on estimates of the electron density (n(e) less than or similar to 2 x 10(11) cm(-3)) from SXT emission measure maps. This study provides the first quantitative localization of the electron acceleration site in a solar hare, and demonstrates that energy-dependent HXR delays offer a sensitive diagnostic for electron acceleration, propagation, and trapping in solar flares. C1 UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. NATL ASTRON OBSERV, MITAKA, TOKYO 181, JAPAN. NASA, GODDARD SPACE FLIGHT CTR, HUGHES STX, GREENBELT, MD 20771 USA. NASA, GODDARD SPACE FLIGHT CTR, LASP, GREENBELT, MD 20771 USA. RP Aschwanden, MJ (reprint author), UNIV MARYLAND, DEPT ASTRON, COLLEGE PK, MD 20742 USA. NR 42 TC 71 Z9 74 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 985 EP 998 DI 10.1086/177386 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400044 ER PT J AU Brage, T Judge, PG Brekke, P AF Brage, T Judge, PG Brekke, P TI Intercombination and allowed transitions in O IV SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; Sun, activity; Sun, flares ID SOLAR SPECTRUM; C-II; LINES; REGION; EMISSION; PROGRAM; IONS; DIAGNOSTICS; EXCITATION AB We report on large-scale ab initio multiconfiguration Hartree-Fock calculations for important multiplets including the UV 0.01 multiplet, 2s(2)2p(2)P(J-)2s2p(24)P(J'), in O IV. The resulting transition probabilities should be accurate to +/- 5%-10% for intersystem lines and 1% or better for permitted lines. We present new calculations of line emission coefficients using these transition probabilities and collisional rate coefficients published by Zhang, Graziani, & Pradhan in 1994. We readdress the use of these lines as diagnostics of electron densities, paying particular attention to uncertainties in density determinations. We find (1) the absolute uncertainties in derived densities are difficult to assess, but are at least +/-40%, controlled by uncertainties in collision strengths; (2) our new calculations bring observed and computed line ratios into better agreement (earlier papers yielding systematically different densities make the agreement worse); (3) there is additional evidence for strong blends in the 1404.8 emission feature, as argued by other authors, and/or evidence for inaccurate laboratory wavelengths; and (4) the computed branching ratios are in good agreement with observed ratios to within observational uncertainties of +/-7%. We determine electron densities in a variety of solar features from HRTS data from the first and second flights of this instrument. The derived electron densities vary remarkably little between quiet Sun network and active regions, but resonance line intensities vary dramatically, and we discuss reasons for this. Finally, we discuss how new high-quality data from the SUMER instrument to be flown on Solar and Heliosphereic Observatory (SOHO) could be used to address outstanding problems concerning blends and heating of the solar transition region. C1 NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. UNIV OSLO,INST THEORET ASTROPHYS,N-0315 OSLO 3,NORWAY. RP Brage, T (reprint author), NRC,GODDARD SPACE FLIGHT CTR,CODE 681,GREENBELT,MD 20771, USA. OI Brage, Tomas/0000-0003-3985-767X NR 56 TC 48 Z9 48 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1996 VL 464 IS 2 BP 1030 EP 1043 DI 10.1086/177390 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA UQ194 UT WOS:A1996UQ19400048 ER PT J AU Ziemke, JR Chandra, S Thompson, AM McNamara, DP AF Ziemke, JR Chandra, S Thompson, AM McNamara, DP TI Zonal asymmetries in southern hemisphere column ozone: Implications of biomass burning SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPOSPHERIC OZONE; SATELLITE AB This study compares Nimbus 7 total ozone mapping spectrometer (TOMS) total column ozone with ozone data from two different satellite instruments measuring vertical profiles of ozone in the stratosphere. The first instrument is the microwave limb sounder (MLS) onboard the upper atmosphere research satellite (UARS) and the second is the solar backscattered ultraviolet (SBUV2) nadir sounder aboard NOAA 11. Previous studies have shown that TOMS data exhibit a zonal wave maximum (amplitudes similar to 20-30 Dobson units) in total column ozone in the tropical South Atlantic region near 0 degrees longitude. This wave structure occurs in all seasons but maximizes around August-October in association with intense biomass burning in South America and southern Africa. Results of this investigation show that MLS stratospheric column ozone integrated between 1 to 68 hPa shows no such feature. Horizontal structures of 1 to 68-hPa MLS column ozone are found to be incoherent with TOMS and SBUV2 total column data in the tropics in all seasons. This study provides the first evidence from a UARS data set that the southern tropical wave 1 peak in TOMS may have relatively small dependence on stratospheric ozone. Combined MLS, TOMS, SBUV2, and ozonesonde station data show that zonal asymmetries observed in total column ozone in the tropics originate primarily from tropospheric effects (dynamics coupled with biomass burning). Outside of the tropics, zonal patterns in total ozone originate mostly from stratospheric dynamics. Wave signatures in TOMS, SBUV2, and MLS column ozone all show generally coherent horizontal structures in middle and high latitudes, especially during seasons of large planetary wave events such as in the southern hemisphere during southern winter-spring. RP Ziemke, JR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, MAIL CODE 916, GREENBELT, MD 20771 USA. RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 14 TC 34 Z9 34 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 JUN 20 PY 1996 VL 101 IS D9 BP 14421 EP 14427 DI 10.1029/96JD01057 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UT467 UT WOS:A1996UT46700006 ER PT J AU MacKenzie, IA Harwood, RS Froidevaux, L Read, WG Waters, JW AF MacKenzie, IA Harwood, RS Froidevaux, L Read, WG Waters, JW TI Chemical loss of polar vortex ozone inferred from UARS MLS measurements of ClO during the Arctic and Antarctic late winters of 1993 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; MICROWAVE LIMB SOUNDER; STRATOSPHERE; DESTRUCTION; CHLORINE; BRO; DEPLETION; CL2O2; CIO AB A computationally cheap, and easily initialized photochemical model utilizing UARS MLS measurements of ClO to calculate ozone destruction rates within the polar vortices due to the ClO + ClO, ClO + BrO, and ClO + O catalytic cycles is developed. The method involves calculating local reactive chlorine concentrations from individual ClO retrievals, and then inferring the diurnal cycle of ClO from a quadratic expression using the relevant kinetic parameters. In test integrations this simple treatment is shown to give good agreement with more detailed model calculations. Analysis of the late Arctic and Antarctic winters of 1993 yields similar vortex-averaged ozone loss rates at 465 K of similar to 1% per day in both hemispheres, while the reactive chlorine remains enhanced. Net ozone destruction in the north is less, largely because the elevated ClO and Cl2O2 concentrations are less persistent. The estimated chemical destruction on isentropic surfaces in the lower stratosphere is broadly similar to the observed change in ozone distribution, implying that the change is dominated by chemical destruction. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP MacKenzie, IA (reprint author), UNIV EDINBURGH, DEPT METEOROL, JAMES CLERK MAXWELL BLDG, KINGS BLDG, MAYFIELD RD, EDINBURGH EH9 3JZ, MIDLOTHIAN, SCOTLAND. RI mackenzie, ian/E-9320-2013 NR 46 TC 23 Z9 23 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 JUN 20 PY 1996 VL 101 IS D9 BP 14505 EP 14518 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UT467 UT WOS:A1996UT46700014 ER PT J AU Atlas, E Ridley, B Walega, J Greenberg, J Kok, G Staffelbach, T Schauffler, S Lind, J Hubler, G Norton, R Liu, S Davis, D Bandy, A Blake, D Bradshaw, J Browell, E Collins, JE Gregory, G Heikes, B Kondo, Y Sachse, G Sandholm, S Singh, H Talbot, B Dlugokencky, E Elkins, J Oltmans, S Mackay, G Karecki, D AF Atlas, E Ridley, B Walega, J Greenberg, J Kok, G Staffelbach, T Schauffler, S Lind, J Hubler, G Norton, R Liu, S Davis, D Bandy, A Blake, D Bradshaw, J Browell, E Collins, JE Gregory, G Heikes, B Kondo, Y Sachse, G Sandholm, S Singh, H Talbot, B Dlugokencky, E Elkins, J Oltmans, S Mackay, G Karecki, D TI A comparison of aircraft and ground-based measurements at Mauna Loa observatory, Hawaii, during GTE PEM-west and MLOPEX 2 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PHOTOCHEMISTRY EXPERIMENT; AIRBORNE MEASUREMENTS; HYDROGEN-PEROXIDE; NITROGEN-DIOXIDE; NITRIC-OXIDE; NITRATE; OZONE; NOY; INSTRUMENT; BUDGET AB During October 19-20, 1991, one flight of the NASA Global Tropospheric Experiment (GTE) Pacific Exploratory Mission (PEM-West A) mission was conducted near Hawaii as an intercomparison with ground-based measurements of the Mauna Loa Observatory Photochemistry Experiment (MLOPEX 2) and the NOAA Climate Modeling and Diagnostics Laboratory (CMDL). Ozone, reactive nitrogen species, peroxides, hydrocarbons, and halogenated hydrocarbons were measured by investigators aboard the DC-8 aircraft and at the ground site. Lidar cross sections of ozone revealed a complex air mass structure near the island of Hawaii which was evidenced by large variation in some trace gas mixing ratios. This variation limited the time and spatial scales for direct measurement intercomparisons. Where differences occurred between measurements in the same air masses, the intercomparison suggested that biases for some trace gases was due to different calibration scales or, in some cases, instrumental or sampling biases. Relatively large uncertainties were associated with those trace gases present in the low parts per trillion by volume range. Trace gas correlations were used to expand the scope of the intercomparison to identify consistent trends between the different data sets. C1 DREXEL UNIV, DEPT CHEM, PHILADELPHIA, PA 19104 USA. UNIV CALIF IRVINE, DEPT CHEM, IRVINE, CA 92717 USA. GEORGIA INST TECHNOL, ATLANTA, GA 30332 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. UNIV RHODE ISL, GRAD SCH OCEANOG, NARRAGANSETT, RI 02882 USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. UNISEARCH ASSOCIATES, CONCORD, ON L4K 1B5, CANADA. NAGOYA UNIV, SOLAR TERR ENVIRONM LAB, TOYOKAWA, AICHI 442, JAPAN. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV NEW HAMPSHIRE, COMPLEX SYST RES CTR, INST EARTH OCEANS & SPACE, DURHAM, NH 03824 USA. RP Atlas, E (reprint author), NATL CTR ATMOSPHER RES, POB 3000, BOULDER, CO 80307 USA. RI Hubler, Gerhard/E-9780-2010; Kondo, Yutaka/D-1459-2012; Atlas, Elliot/J-8171-2015 NR 41 TC 7 Z9 7 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 JUN 20 PY 1996 VL 101 IS D9 BP 14599 EP 14612 DI 10.1029/96JD00213 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA UT467 UT WOS:A1996UT46700021 ER PT J AU Vaidehi, N Jain, A Goddard, WA AF Vaidehi, N Jain, A Goddard, WA TI Constant temperature constrained molecular dynamics: The Newton-Euler inverse mass operator method SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID FORCE-FIELD; SIMULATIONS; EQUILIBRIUM AB The Newton-Euler inverse mass operator (NEIMO) method for internal coordinate molecular dynamics (MD) of macromolecules (proteins and polymers) leads to stable dynamics for time steps about 10 times larger than conventional dynamics (e.g., 20 or 30 fs rather than 1 or 2 fs for systems containing hydrogens). NEIMO is practical for large systems since the computation time scales linearly with the number of degrees of freedom N(instead of the N-3 scaling for conventional constrained MD methods). In this paper we generalize the NEIMO formalism to the Nose (and Hoover) thermostat to derive the Nose and Hoover equations of motion for constrained canonical ensemble molecular dynamics. We also examined the optimum mass, Q, determining the time scale (tau(s)) for exchange of energy with the heat bath for NEIMO-Hoover dynamics of polymers. We carried out NEIMO-Hoover simulations on the amorphous polymers poly(vinyl chloride) and poly(vinylidene fluoride), where we find that time steps of 20-30 fs lead to stable dynamics (10 times larger than for Cartesian dynamics). The computational efficiency of the NEIMO canonical MD method should make it a powerful tool for MD simulations of macromolecular materials. C1 CALTECH,MAT & PROC SIMULAT CTR,BECKMAN INST 13974,DIV CHEM & CHEM ENGN CN 9114,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 25 TC 56 Z9 56 U1 0 U2 12 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUN 20 PY 1996 VL 100 IS 25 BP 10508 EP 10517 DI 10.1021/jp953043o PG 10 WC Chemistry, Physical SC Chemistry GA UT213 UT WOS:A1996UT21300002 ER PT J AU Sokolik, IN Toon, OB AF Sokolik, IN Toon, OB TI Direct radiative forcing by anthropogenic airborne mineral aerosols SO NATURE LA English DT Article ID ATMOSPHERIC DUST AEROSOLS; SAHARAN DUST; DISTRIBUTIONS; TRANSPORT; BUDGET AB AIRBORNE mineral dust can have a significant effect on the Earth's radiation budget, as it can both scatter sunlight back to space (leading to negative radiative forcing), and absorb solar and infrared radiation (leading to positive forcing)(1,2). The effects of mineral aerosols on the radiation budget are important relative to those of other types of aerosols-such as sulphate and smoke particles-due to the widespread distribution and large optical depth of mineral dust, Various human activities, such as land use practices, can result in additional loading of dust, increasing the radiative forcing, Previous studies have attempted to estimate the radiative effects of both the natural and anthropogenic components of the dust(3,4). Here we use estimates of anthropogenic dust inputs and observations of dust optical properties to show that although the key quantities contributing to the evaluation of the direct solar radiative forcing by dust generated through human activities have a wide range of uncertainty, the forcing by anthropogenically generated mineral aerosols may be comparable to the forcing by other anthropogenic aerosols, On a regional scale the forcing due to mineral aerosols can greatly exceed that due to sulphate aerosols and can be comparable to that of clouds, Our analysis enables us to highlight the key quantities that need to be better characterized to reduce the (currently large) uncertainties in these estimates. RP Sokolik, IN (reprint author), NASA, AMES RES CTR, DIV EARTH SCI, MAIL STOP 245-4, MOFFETT FIELD, CA 94035 USA. NR 34 TC 444 Z9 474 U1 12 U2 59 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JUN 20 PY 1996 VL 381 IS 6584 BP 681 EP 683 DI 10.1038/381681a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA UR979 UT WOS:A1996UR97900046 ER PT J AU Hochstein, LI AF Hochstein, LI TI Is the Paracoccus halodenitrificans ATPase a chimeric enzyme? SO FEMS MICROBIOLOGY LETTERS LA English DT Article DE ATPase; Paracoccus halodenitrificans; halophile; bafilomycin; concanamycin; N-ethylmaleimide; p-chloromercuriphenylsufonate ID ESCHERICHIA-COLI; H+-ATPASE; PURIFICATION; BAFILOMYCINS; BACTERIUM AB Membranes from Paracoccus halodenitrificans contain an ATPase that is most active in the absence of NaCl. The most unusual characteristic of the enzyme is its pattern of sensitivity to various inhibitors. Azide and rhodamine 6G, inhibitors of F1F0-ATPases, inhibit ATP hydrolysis as do bafilomycin A(1), concanamycin A (folimycin), N-ethylmaleimide, and p-chloromercuriphenylsulfonate which are inhibitors of vacuolar ATPases. This indiscriminate sensitivity suggests that this ATPase may be a hybrid and that caution should be exercised when using inhibition as a diagnostic for distinguishing between F1F0-ATPases and vacuolar ATPases. RP Hochstein, LI (reprint author), NASA,AMES RES CTR,EXOBIOL BRANCH,MOFFETT FIELD,CA 94035, USA. NR 27 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-1097 J9 FEMS MICROBIOL LETT JI FEMS Microbiol. Lett. PD JUN 15 PY 1996 VL 140 IS 1 BP 55 EP 60 PG 6 WC Microbiology SC Microbiology GA UV582 UT WOS:A1996UV58200009 PM 11536735 ER PT J AU Garraffo, ZD Kamenkovich, VM AF Garraffo, ZD Kamenkovich, VM TI A note on the transport of the Brazil Current SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CIRCULATION; THERMOCLINE; ATLANTIC; WATER AB Stommel's hypothesis on the influence of the thermohaline circulation on the transport of the Brazil Current is illustrated using the product of Semtner and Chervin's model. The velocity distribution along specifically chosen zonal sections is analyzed. A procedure of singling out the thermohaline component of the circulation is suggested and the significance of the component is proved. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964. RP Garraffo, ZD (reprint author), COLUMBIA UNIV,DEPT APPL PHYS,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 12 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1996 VL 23 IS 13 BP 1629 EP 1632 DI 10.1029/96GL01369 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UT009 UT WOS:A1996UT00900021 ER PT J AU Pougatchev, NS Connor, BJ Jones, NB Rinsland, CP AF Pougatchev, NS Connor, BJ Jones, NB Rinsland, CP TI Validation of ozone profile retrievals from infrared ground-based solar spectra SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB A direct validation of ozone profile retrievals from IR ground-based high resolution solar spectra has been performed. The spectra were recorded at 0.0035 to 0.01 cm(-1) resolution on 11 days between February and October 1994 at the Network for the Detection of Stratospheric Change station-in Lauder, New Zealand (45.04 degrees S, 169.68 degrees E, 0.37 km altitude) and analyzed for the O-3 profile with a line-by-line forward model and semi empirical application of the optimal estimation inversion technique of Rodgers. The line parameters on the 1992 HITRAN compilation were assumed in the analysis. Retrieved ozone columns in three atmospheric layers (0.37-12 km, 12-20 km, and 20-100 km) have been compared with correlative ozonesondes, microwave and Dobson spectrometer data from the same site. IR total and O-3 col- umns above 20 km agree with Dobson and microwave measurements to better than 2%. For the layers 0.37-12 km and 12-20 km the differences between IR and integrated ozonesondes are -7+/-5% and 2+/-4%, respectively. Special exercises have been performed to show the applicability of the retrieval method to spectra with a resolution and better. C1 NATL INST WATER & ATMOSPHER RES,LAUDER,NEW ZEALAND. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. RP Pougatchev, NS (reprint author), CHRISTOPHER NEWPORT UNIV,NEWPORT NEWS,VA 23606, USA. RI Jones, Nicholas/G-5575-2011 OI Jones, Nicholas/0000-0002-0111-2368 NR 17 TC 30 Z9 30 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1996 VL 23 IS 13 BP 1637 EP 1640 DI 10.1029/96GL01501 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UT009 UT WOS:A1996UT00900023 ER PT J AU Fahey, DW Donnelly, SG Keim, ER Gao, RS Wamsley, RC DelNegro, LA Woodbridge, EL Proffitt, MH Rosenlof, KH Ko, MKW Weisenstein, DK Scott, CJ Nevison, C Solomon, S Chan, KR AF Fahey, DW Donnelly, SG Keim, ER Gao, RS Wamsley, RC DelNegro, LA Woodbridge, EL Proffitt, MH Rosenlof, KH Ko, MKW Weisenstein, DK Scott, CJ Nevison, C Solomon, S Chan, KR TI In situ observations of NOy, O-3, and the NOy/O-3 ratio in the lower stratosphere SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE ATMOSPHERE; OZONE; MODEL AB Extensive in situ measurements of reactive nitrogen (NOy) and ozone (O-3) were made in the lower stratosphere over a broad latitude range (60 degrees N-70 degrees S) during two different seasons (March and October) in 1994. Both NOy and O-3 mixing ratios show a strong latitude dependence, with values increasing toward the poles. The NOy/O-3 ratio reveals a high-gradient region near the tropics that is not well-represented in standard 2-D photochemical transport models. Improving the representation by changing the horizontal eddy-diffusion coefficients near the tropics has important implications for the predicted impacts of aircraft emissions on stratospheric O-3. C1 UNIV COLORADO,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. UNIV COLORADO,DEPT CHEM & BIOCHEM,BOULDER,CO 80309. UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,CTR CLOUDS CLIMATE & CHEM,LA JOLLA,CA 92093. ATMOSPHER & ENVIRONM RES INC,CAMBRIDGE,MA 02139. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP Fahey, DW (reprint author), NOAA,AERON LAB,325 BROADWAY,BOULDER,CO 80303, USA. RI Gao, Ru-Shan/H-7455-2013; Rosenlof, Karen/B-5652-2008; Ko, Malcolm/D-5898-2015; Fahey, David/G-4499-2013 OI Rosenlof, Karen/0000-0002-0903-8270; Fahey, David/0000-0003-1720-0634 NR 19 TC 43 Z9 43 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1996 VL 23 IS 13 BP 1653 EP 1656 DI 10.1029/96GL01476 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UT009 UT WOS:A1996UT00900027 ER PT J AU Hansen, J Ruedy, R Sato, M Reynolds, R AF Hansen, J Ruedy, R Sato, M Reynolds, R TI Global surface air temperature in 1995: Return to pre-Pinatubo level SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CLIMATE AB Global surface air temperature has increased about 0.5 degrees C from the minimum of mid-1992, a year after the Mt. Pinatubo eruption. Both a land-based surface air temperature record and a land-marine temperature index place the meteorological year 1995 at approximately the same level as 1990, previously the warmest year in the period of instrumental data. As El Nino warming was small in 1995, the solar cycle near a minimum, and ozone depletion near record levels, the observed high temperature supports the contention of an underlying global warming trend. The pattern of Northern Hemisphere temperature change in recent decades appears to reflect a change of atmospheric dynamics. C1 NOAA,NATL CTR ENVIRONM PREDICT,CAMP SPRINGS,MD 20746. RP Hansen, J (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 28 TC 116 Z9 121 U1 2 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1996 VL 23 IS 13 BP 1665 EP 1668 DI 10.1029/96GL01040 PG 4 WC Geosciences, Multidisciplinary SC Geology GA UT009 UT WOS:A1996UT00900030 ER EF