FN Thomson Reuters Web of Science™ VR 1.0 PT B AU Hu, H Liu, WT AF Hu, H Liu, WT GP AMS AMS TI Monitoring Saharan dust events using integrated observing systems SO SYMPOSIUM ON CLIMATE VARIABILITY, THE OCEANS AND SOCIETAL IMPACTS LA English DT Proceedings Paper CT Symposium on Climate Variability, the Oceans and Societal Impacts CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Hu, H (reprint author), Jet Prop Lab, MS 300-323,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2001 BP 35 EP 38 PG 4 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA BU98Y UT WOS:000177563900008 ER PT B AU Adler, RF Curtis, S Huffman, G Bolvin, D Nelkin, E AF Adler, RF Curtis, S Huffman, G Bolvin, D Nelkin, E GP AMS AMS TI The magnitude and variability of global and regional precipitation based on the 22-year GPCP (global precipitatiion climatology project) and three-year TRMM (tropical rainfall measuring,mission) data sets SO SYMPOSIUM ON CLIMATE VARIABILITY, THE OCEANS AND SOCIETAL IMPACTS LA English DT Proceedings Paper CT Symposium on Climate Variability, the Oceans and Societal Impacts CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Adler, RF (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. NR 2 TC 0 Z9 0 U1 0 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2001 BP 87 EP 93 PG 7 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA BU98Y UT WOS:000177563900019 ER PT B AU Huffman, GJ Adler, RF Bolvin, DT Curtis, S AF Huffman, GJ Adler, RF Bolvin, DT Curtis, S GP AMS AMS TI Extending the precipitation map offshore using daily and 3-hourly combined precipitation estimates SO SYMPOSIUM ON PRECIPITATION EXTREMES: PREDICTION, IMPACTS, AND RESPONSES LA English DT Proceedings Paper CT Symposium on Precipitation Extremes - Prediction, Impacts and Responses CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. RP Huffman, GJ (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Code 912, Greenbelt, MD 20771 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2001 BP 75 EP 76 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV03A UT WOS:000177651600021 ER PT B AU Chiu, LS Liu, Z Teng, B Serafino, G Morain, S Budge, A Bales, C Wulff, T AF Chiu, LS Liu, Z Teng, B Serafino, G Morain, S Budge, A Bales, C Wulff, T GP AMS AMS TI Comparison of TRMM and rain gage rain rates over New Mexico SO SYMPOSIUM ON PRECIPITATION EXTREMES: PREDICTION, IMPACTS, AND RESPONSES LA English DT Proceedings Paper CT Symposium on Precipitation Extremes - Prediction, Impacts and Responses CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc ID MICROWAVE C1 NASA, Goddard Space Flight Ctr, GES Data & Informat Serv Ctr, Greenbelt, MD 20771 USA. RP Chiu, LS (reprint author), NASA, Goddard Space Flight Ctr, GES Data & Informat Serv Ctr, Code 902, Greenbelt, MD 20771 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2001 BP 199 EP 203 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV03A UT WOS:000177651600052 ER PT B AU Sandford, SA AF Sandford, SA BE Woodward, CE Biscay, MD Shull, JM TI The composition of organics and volatiles in the interstellar medium SO TETONS 4: GALACTIC STRUCTURE, STARS, AND THE INTERSTELLAR MEDIUM SE Astronomical Society of the Pacific Conference Series LA English DT Proceedings Paper CT 4th Tetons Conference on Galactic Structure, Stars, and the Interstellar Medium CY MAY 28-JUN 01, 2000 CL GRAND TETON NATL PK, WY SP SIRFT ID POLYCYCLIC AROMATIC-HYDROCARBONS; TIME-DEPENDENT CHEMISTRY; DENSE MOLECULAR CLOUDS; INTERPLANETARY DUST PARTICLES; INFRARED SPECTRAL PROPERTIES; GRAIN SURFACE-REACTIONS; IR EMISSION FEATURES; ICE ANALOGS; ABSORPTION FEATURES; MICRON ABSORPTION AB Tremendous progress has been made in our understanding of the composition of interstellar dust through the combined use of telescopic observations, theoretical models, laboratory studies of analogs, and the analysis of 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 paper reviews some of our current knowledge of the organic and volatile materials thought to exist in the ISM. These compounds supply a significant portion of the material that makes up the interstellar dense molecular clouds from which new stars and planetary systems are formed, and thus represents an important reservoir of material that could play key roles in the formation and evolution of life. This paper will largely focus 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 brief discussion of the astrobiological relevance of some of the compounds now known or suspected to be present in the ISM. C1 NASA, Ames Res Ctr, Astrophys Branch, Moffett Field, CA 94035 USA. RP Sandford, SA (reprint author), NASA, Ames Res Ctr, Astrophys Branch, Mail Stop 245-6, Moffett Field, CA 94035 USA. NR 95 TC 1 Z9 1 U1 0 U2 1 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-064-1 J9 ASTR SOC P PY 2001 VL 231 BP 152 EP 170 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU31M UT WOS:000175667600015 ER PT B AU Kutyrev, A Bennet, CL Moseley, SH Reynolds, RJ Roesler, FL AF Kutyrev, A Bennet, CL Moseley, SH Reynolds, RJ Roesler, FL BE Woodward, CE Biscay, MD Shull, JM TI Brackett-gamma line survey of the ionized hydrogen in the galactic plane SO TETONS 4: GALACTIC STRUCTURE, STARS, AND THE INTERSTELLAR MEDIUM SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT 4th Tetons Conference on Galactic Structure, Stars, and the Interstellar Medium CY MAY 28-JUN 01, 2000 CL GRAND TETON NATL PK, WY SP SIRFT AB We report on the first results of a pilot program to carry out a 2.1655 mum Brackett-gamma hydrogen recombination emission line survey of the Galactic plane. The survey has been carried out with the Goddard-Wisconsin near-infrared cryogenic Fabry-Perot spectrometer. The typical detected intensities correspond to emission measures of 10(3) cm(-6)pc. The detected emission line intensities vary on a typical scale of 1degrees or less and can be considered as additional evidence of extremely clumpy structure of the interstellar gas in the inner Galaxy. When completed, the survey will provide a large scale map of the ionized hydrogen in the inner Galaxy and total Lyman continuum luminosity. C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD USA. RP Kutyrev, A (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD USA. RI Moseley, Harvey/D-5069-2012 NR 4 TC 2 Z9 2 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-064-1 J9 ASTR SOC P PY 2001 VL 231 BP 360 EP 361 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU31M UT WOS:000175667600044 ER PT B AU Sahai, R AF Sahai, R BE Woodward, CE Biscay, MD Shull, JM TI The extraordinary death of ordinary stars - The impact of HST SO TETONS 4: GALACTIC STRUCTURE, STARS, AND THE INTERSTELLAR MEDIUM SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT 4th Tetons Conference on Galactic Structure, Stars, and the Interstellar Medium CY MAY 28-JUN 01, 2000 CL GRAND TETON NATL PK, WY SP SIRFT ID BIPOLAR PROTOPLANETARY NEBULA; PLANETARY-NEBULAE; CIRCUMSTELLAR ENVELOPES; AGB STARS; DISCOVERY; EMISSION; JETS; EVOLUTION AB With the advent of the Wide Field Planetary Camera 2 (WFPC2) onboard the Hubble Space Telescope (HST) in December 1993, a growing number of young planetary and proto-planetary nebulae (PNe and PPNe) have been imaged with unprecedented high angular resolution and dynamic range. These objects represent the last phases of the evolution of intermediate-mass (1 - 8 M-circle dot) stars. Our WFPC2 Halpha SNAPshot imaging survey of young planetary nebulae (selected only on the basis of their low excitation) show that these objects have highly aspherical, with complex multipolar morphologies. The central star is often systematically offset from the geometrical symmetry centers of various nebular components. The bright aspherical nebulae are often found to be surrounded by faint, roughly round halos - signatures of the progenitor AGB envelopes produced by isotropic mass-loss. A number of these halos include numerous concentric arcs, evidence for quasi-periodic modulation of the mass-loss on time-scales of a few hundred years. Our detailed imaging studies of PPNe (objects in transition between the AGB and PN evolutionary phases) shows the emergence of complex morphological structures during the PPN phase. The complexity, organization and symmetry of the morphological structures we find is forcing radical changes in, and inspiring fresh theoretical efforts to advance, our understanding of the mass-loss processes during late stellar evolution. In this paper, we review the HST data, and show some of the highlights of our imaging studies. Although the origins of many of the morphological features remains puzzling, we find that the data support a model for PN formation in which the primary agent for shaping PNe are high-speed collimated outflows or jets which operate during the late AGB and/or early post-AGB evolutionary phase. The multipolar shapes indicate that these outflows are bipolar and undergo episodic changes in their orientation and/or multiple collimated outflows occur with different orientations. Our discovery of a very highly-collimated, knotty bipolar jet in a planetary nebula, and its amazing morphological similarity to a low-mass YSO provides strong empirical evidence for a common physical mechanism for generating collimated outflows in protostars and evolved stars. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sahai, R (reprint author), CALTECH, Jet Prop Lab, MS183-900,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 42 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-064-1 J9 ASTR SOC P PY 2001 VL 231 BP 528 EP 538 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU31M UT WOS:000175667600065 ER PT B AU Stapelfeldt, K AF Stapelfeldt, K BE Woodward, CE Biscay, MD Shull, JM TI A hubble space telescope Imaging survey of nearby T Tauri stars SO TETONS 4: GALACTIC STRUCTURE, STARS, AND THE INTERSTELLAR MEDIUM SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT 4th Tetons Conference on Galactic Structure, Stars, and the Interstellar Medium CY MAY 28-JUN 01, 2000 CL GRAND TETON NATL PK, WY SP SIRFT AB It has been known for more than a decade that young T Tauri stars possess infrared and millimeter continuum excess emission suggestive of circumstellar disks. Millimeter interferometers provided the first resolved images of these disks, but at limited angular resolutions > 1 arcsec. Disk images with an order of magnitude better resolution can be made in optical and near-IR reflected light using the Hubble Space Telescope. In this contribution, we summarize the first extensive deep imaging survey of nearby T Tauri stars using HST. The sample consists of 110 young stars associated with the Taurus-Auriga, Chamaeleon, Lupus, Ophiuchus, and Corona Australis star-forming clouds at distances ranging from 140-160 pc. All of the targets possess millimeter continuum emission indicating the presence of circumstellar disks, and/or optical polarization suggesting the presence of compact reflection nebulosity. The images were made using the WFPC2 camera in two snapshot observing programs.. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Stapelfeldt, K (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Stapelfeldt, Karl/D-2721-2012 NR 2 TC 2 Z9 2 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-064-1 J9 ASTR SOC P PY 2001 VL 231 BP 620 EP 621 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU31M UT WOS:000175667600077 ER PT B AU Leisawitz, D Yorke, HW AF Leisawitz, D Yorke, HW BE Woodward, CE Biscay, MD Shull, JM TI The uniqueness space for SPIRIT and SPECS SO TETONS 4: GALACTIC STRUCTURE, STARS, AND THE INTERSTELLAR MEDIUM SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT 4th Tetons Conference on Galactic Structure, Stars, and the Interstellar Medium CY MAY 28-JUN 01, 2000 CL GRAND TETON NATL PK, WY SP SIRFT C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Leisawitz, D (reprint author), NASA, Goddard Space Flight Ctr, Code 631, Greenbelt, MD 20771 USA. NR 3 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-064-1 J9 ASTR SOC P PY 2001 VL 231 BP 639 EP 640 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU31M UT WOS:000175667600082 ER PT S AU Shields, VB Caillat, T AF Shields, VB Caillat, T BE Nolas, GS Johnson, DC Mandrus, DG TI Synthesis and thermoelectric properties of CoP3 SO THERMOELECTRIC MATERIALS 2001-RESEARCH AND APPLICATIONS SE MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS LA English DT Proceedings Paper CT Symposium on Thermoelectric Materials 2001 - Research and Applications held at the 2001 MRS Fall Meeting CY NOV 26-29, 2001 CL BOSTON, MA SP Mat Res Soc ID SKUTTERUDITES; COSB3 AB In an effort to expand the range of operation for highly efficient, segmented thermoelectric unicouples currently being developed at the Jet Propulsion Laboratory (JPL), skutterudite phosphides are being investigated as potential high temperature segments to supplement antimonide segments that limit the use of these unicouples at a hot-side temperature of about 873-973 K. We report here on the synthesis and transport properties of one of these phosphide skutterudite materials, CoP3. Large amounts of cobalt triphosphide have been prepared by direct reaction from stochiometric powders at synthesis temperatures ranging from 873 to 12.23 K. The synthesized powders were analyzed by x-ray diffractometry and hot pressed at 1273 K. The samples were analyzed by microprobe analysis and electrical conductivity, Seebeck voltage and thermal conductivity measurements were performed. The thermoelectric properties are presented and discussed as a function of temperature up to 1000 K. Initial thermal stability results are presented to assess the potential of this material for high temperature operation. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Shields, VB (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 0 Z9 0 U1 1 U2 3 PU MATERIALS RESEARCH SOCIETY PI WARRENDALE PA 506 KEYSTONE DRIVE, WARRENDALE, PA 15088-7563 USA SN 0272-9172 BN 1-55899-627-3 J9 MATER RES SOC SYMP P PY 2001 VL 691 BP 55 EP 62 PG 8 WC Materials Science, Multidisciplinary; Materials Science, Composites; Physics, Condensed Matter SC Materials Science; Physics GA BU84C UT WOS:000177163500007 ER PT S AU Cramer, KE Jacobstein, R Reilly, T AF Cramer, KE Jacobstein, R Reilly, T BE Rozlosnik, AE Dinwiddie, RB TI Boiler tube corrosion characterization with a scanning thermal line SO THERMOSENSE XXIII SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Thermosense XXIII Conference CY APR 16-19, 2001 CL ORLANDO, FL SP SPIE DE infrared; thermal; NDE; corrosion; boiler tubes ID AIRCRAFT AB Wall thinning due to corrosion in utility boiler waterwall tubing is a significant operational concern for boiler operators. Historically, conventional ultrasonics has been used for inspection of these tubes. Unfortunately, ultrasonic inspection is very manpower intense and slow. Therefore, thickness measurements are typically taken over a relatively small percentage of the total boiler wall and statistical analysis is used to determine the overall condition of the boiler tubing. Other inspection techniques, such as electromagnetic acoustic transducer (EMAT), have recently been evaluated, however they provide only a qualitative evaluation - identifying areas or spots where corrosion has significantly reduced the wall thickness. NASA Langley Research Center, in cooperation with ThermTech Services, has developed a thermal NDE technique designed to quantitatively measure the wall thickness and thus determine the amount of material thinning present in steel boiler tubing. The technique involves the movement of a thermal line source across the outer surface of the tubing followed by an infrared imager at a fixed distance behind the line source. Quantitative images of the material loss due to corrosion are reconstructed from measurements of the induced surface temperature variations. This paper will present a discussion of the development of the thermal imaging system as well as the techniques used to reconstruct images of flaws. The application of the thermal line source coupled with the analysis technique represents a significant improvement in the inspection speed and accuracy for large structures such as boiler waterwalls. A theoretical basis for the technique will be presented to establish the quantitative nature of the technique. Further, a dynamic calibration system will be presented for the technique that allows the extraction of thickness information from the temperature data. Additionally, the results of the application of this technology to actual waterwall tubing samples and insitu inspections will be presented. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Cramer, KE (reprint author), NASA, Langley Res Ctr, 4 Langley Blvd,Mail Stop 231, Hampton, VA 23681 USA. RI 苏, 日亮/D-4386-2009 NR 7 TC 9 Z9 9 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4055-8 J9 P SOC PHOTO-OPT INS PY 2001 VL 4360 BP 594 EP 605 DI 10.1117/12.421047 PG 12 WC Thermodynamics; Instruments & Instrumentation; Optics SC Thermodynamics; Instruments & Instrumentation; Optics GA BS34B UT WOS:000169530500070 ER PT S AU Winfree, WP Heath, DM Cramer, KE AF Winfree, WP Heath, DM Cramer, KE BE Rozlosnik, AE Dinwiddie, RB TI Thermal diffusivity imaging with a moving line source SO THERMOSENSE XXIII SE Proceedings of SPIE LA English DT Proceedings Paper CT Thermosense XXIII Conference CY APR 16-19, 2001 CL ORLANDO, FL SP SPIE DE infrared; thermal; NDE; thermal diffusivity; composites; porosity ID TRANSIENT THERMOGRAPHY; IMAGES; SHAPE AB The thermal line scan technique has been shown to be an effective technique for rapid inspection of aerospace specimens. Past efforts have focused on thermal measurements far behind the line source where the heat flow normal to the surface is negligible. This paper focuses on measurements closer to the line source to enable the measurement of the thermal diffusivity in the surface normal direction. This measurement also enables an independent characterization of the thermal diffusivity in the direction of motion of the thermal line source. An analytical solution is given for a line source moving with constant velocity across an anisotropic plane. A nonlinear least squares fitting routine is used to reduce the temporal response of a specimen to images of the thermal diffusivity in both the directions normal to the surface and parallel to the motion of the line source. Measurements are presented on specimens with known variations in effective diffusivity. Measurements on these specimens allow a comparison of this technique to more conventional techniques for diffusivity measurement. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, MS 231, Hampton, VA 23681 USA. NR 16 TC 3 Z9 3 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4055-8 J9 PROC SPIE PY 2001 VL 4360 BP 606 EP 615 DI 10.1117/12.421035 PG 10 WC Thermodynamics; Instruments & Instrumentation; Optics SC Thermodynamics; Instruments & Instrumentation; Optics GA BS34B UT WOS:000169530500071 ER PT S AU Zalameda, JN AF Zalameda, JN BE Rozlosnik, AE Dinwiddie, RB TI Synchronized electronic shutter system (SESS) for thermal nondestructive evaluation SO THERMOSENSE XXIII SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Thermosense XXIII Conference CY APR 16-19, 2001 CL ORLANDO, FL SP SPIE DE thermography; single side inspection; flash lamp; electronic shutters; corrosion; disbond; delamination AB The purpose of this paper is to describe a new method for thermal nondestructive evaluation. This method uses a synchronized electronic shutter system (SESS) to remove the heat lamp's influence on the thermal data during and after flash heating. There are two main concerns when using flash heating. The first concern is during the flash when the photons are reflected back into the camera. This tends to saturate the detectors and potentially introduces unknown and uncorrectable errors when curve fitting the data to a model. To address this, an electronically controlled shutter was placed over the infrared camera lens. Before firing the flash lamps, the shutter is opened to acquire the necessary background data for offset calibration. During flash heating, the shutter is closed to prevent the photons from the high intensity flash from saturating the camera's detectors. The second concern is after the flash heating where the lamps radiate heat after firing. This residual cooling introduces an unwanted transient thermal response into the data. To remove this residual effect, a shutter was placed over the flash lamps to block the infrared heat radiating from the flash head after heating. This helped to remove the transient contribution of the flash. The flash lamp shutters were synchronized electronically with the camera shutter. Results are given comparing the use of the thermal inspection with and without the shutter system. C1 NASA, Langley Res Ctr, USA Res Lab, Nondestruct Evaluat Sci Branch, Hampton, VA 23681 USA. RP Zalameda, JN (reprint author), NASA, Langley Res Ctr, USA Res Lab, Nondestruct Evaluat Sci Branch, MS 231, Hampton, VA 23681 USA. NR 9 TC 6 Z9 6 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4055-8 J9 P SOC PHOTO-OPT INS PY 2001 VL 4360 BP 616 EP 623 DI 10.1117/12.421044 PG 8 WC Thermodynamics; Instruments & Instrumentation; Optics SC Thermodynamics; Instruments & Instrumentation; Optics GA BS34B UT WOS:000169530500072 ER PT B AU Stoica, A Zebulum, R Keymeulen, D AF Stoica, A Zebulum, R Keymeulen, D BE Keymeulen, D Stoica, A Lohn, J Zebulum, RS TI Progress and challenges in building evolvable devices SO THIRD NASA/DOD WORKSHOP ON EVOLVABLE HARDWARE, PROCEEDINGS LA English DT Proceedings Paper CT 3rd NASA/DoD Workshop on Evolvable Hardware (EH-2001) CY JUL 12-14, 2001 CL LONG BEACH, CA SP NASA, US Dept Def, Def Adv Res Projects Agcy, Caltech, Jet Prop Lab AB This paper presents JPL progress in building evolution-oriented reconfigurable devices. It surveys the FPTA family, and presents details of the latest chip, FPTA2, an array of 64 reconfigurable cells that can implement mixed-signal functions, include programmable capacitors and resistors and integrate photodetectors as part of a built-in vision sensor. The chip was fabricated in 0.18 micron CMOS. The paper also discusses some of the challenges in building such chips, as well as lessons learned while evolving circuits. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Stoica, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 15 Z9 15 U1 0 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-1180-5 PY 2001 BP 33 EP 35 DI 10.1109/EH.2001.937944 PG 3 WC Engineering, Aerospace; Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic; Robotics SC Engineering; Computer Science; Robotics GA BS63J UT WOS:000170639500004 ER PT B AU Stoica, A Keymeulen, D Zebulum, R AF Stoica, A Keymeulen, D Zebulum, R BE Keymeulen, D Stoica, A Lohn, J Zebulum, RS TI Evolvable hardware solutions for extreme temperature electronics SO THIRD NASA/DOD WORKSHOP ON EVOLVABLE HARDWARE, PROCEEDINGS LA English DT Proceedings Paper CT 3rd NASA/DoD Workshop on Evolvable Hardware (EH-2001) CY JUL 12-14, 2001 CL LONG BEACH, CA SP NASA, US Dept Def, Def Adv Res Projects Agcy, Caltech, Jet Prop Lab AB Temperature and radiation tolerant electronics, as well as long life survivability are key, capabilities required for future NASA missions. Current approaches to electronics,for extreme environments focus on component level robustness and hardening. Compensation techniques such as bias cancellation circuitry have also been employed. However, current technology can only ensure very limited lifetime in extreme environments. This paper presents a novel approach, based on evolvable hardware technology, which allows adaptive in-situ circuit redesign/reconfiguration during operation in extreme environments. This technology would complement material/device advancements and increase the mission capability to survive harsh environments. The approach is demonstrated on a prototype chip, which recovers functionality at 250 degreesC. Besides the applications that provide adaptive reconfiguration, evolutionary, algorithms can be used to automatically design (fixed) circuits for high temperatures. While simulations show that conventional AND gate design fails at high temperatures such as 320 degreesC, evolution is able to synthesize AND gate circuits operating accurately at this temperature. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM adrian.stoica@jpl.nasa.gov NR 12 TC 18 Z9 19 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-1180-5 PY 2001 BP 93 EP 97 PG 5 WC Engineering, Aerospace; Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic; Robotics SC Engineering; Computer Science; Robotics GA BS63J UT WOS:000170639500010 ER PT B AU Kelley, OA Stout, J Kafatos, M AF Kelley, OA Stout, J Kafatos, M BE Kerschberg, L Kafatos, M TI Content-based browsing of data from the Tropical Rainfall Measuring Mission (TRMM) SO THIRTEENTH INTERNATIONAL CONFERENCE ON SCIENTIFIC AND STATISTICAL DATABASE MANAGEMENT, PROCEEDINGS LA English DT Proceedings Paper CT 13th International Conference on Scientific and Statistical Database Management (SSDBM 2001) CY JUL 18-20, 2001 CL FAIRFAX, VA SP Ctr Earth Observing & Space Res, Ctr Informat Syst Integrat & Evolut, E Ctr for E Business, George Mason Univ, ACM SIGMOD, IEEE TC Data Engn, VLDB Endowment AB Through content-based browsing, the TSDIS Orbit Viewer can help scientists decide which files to order from the TRMM archive. The Orbit Viewer's Mission Index can locate large-scale rain events in six terabytes of data. The Orbit Viewer's TRMM Tracker can locate coincidences between the TRMM orbit and a user-defined surface track. C1 NASA, Goddard Space Flight Ctr, TRMM Sci Data & Informat Syst, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, TRMM Sci Data & Informat Syst, Greenbelt, MD 20771 USA. EM owen.kelley@gsfc.nasa.gov; john.stout@gsfc.nasa.gov; mkafatos@gmu.edu NR 7 TC 0 Z9 0 U1 0 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-1218-6 PY 2001 BP 270 EP 273 DI 10.1109/SSDM.2001.938562 PG 4 WC Computer Science, Information Systems SC Computer Science GA BS91R UT WOS:000171370000028 ER PT S AU Imhoff, ML Lawrence, WT Tucker, CJ Stutzer, D AF Imhoff, ML Lawrence, WT Tucker, CJ Stutzer, D BE Rahm, J McCabe, R TI A satellite survey of the impact of urban sprawl on agriculture and primary productivity in the United States: Is our style of development sustainable? SO TRANSACTIONS OF THE SIXTY-SIXTH NORTH AMERICAN WILDLIFE AND NATURAL RESOURCES CONFERENCE SE TRANSACTIONS OF THE NORTH AMERICAN WILDLIFE AND NATURAL RESOURCES CONFERENCE LA English DT Proceedings Paper CT 66th North-American Wildlife and Natural Resources Conference CY MAR 16-20, 2001 CL WASHINGTON, D.C. SP Boone & Crockett Club, Conservat Fund, Defenders Wildlife, Fed Cartridge Co, Izaak Walton League Amer, Natl Rifle Assoc Amer, Natl Shooting Sports Fdn, Natl Wild Turkey Federat, Rocky Mt Elk Fdn, US Bur Land Management, USDA Anim & Plant Hlth Inspect Serv, USDA Forest Serv, USDA Natl Resources Conservat Serv, USDI Bur Reclamat, US Fish & Wildlife Serv, US Geol Survey, Biol Resources Div, Wilderness Soc, Wildlife Soc ID LEAF-AREA INDEX; CITY LIGHTS; SPECTRAL REFLECTANCE; CANOPY REFLECTANCE; RADIATION; POPULATION; PHOTOSYNTHESIS; SYSTEM; WHEAT C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Imhoff, ML (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 40 TC 1 Z9 1 U1 0 U2 2 PU WILDLIFE MANAGEMENT INST PI WASHINGTON PA 1146 19TH ST, NW, STE 700, WASHINGTON, DC 20036 USA SN 0078-1355 J9 T N AM WILDL NAT RES PY 2001 BP 392 EP 404 PG 13 WC Biodiversity Conservation; Ecology; Zoology SC Biodiversity & Conservation; Environmental Sciences & Ecology; Zoology GA BT71X UT WOS:000173844500029 ER PT B AU Noor, AK Starnes, JH AF Noor, AK Starnes, JH BE Wall, WA Bletzinger, KU Schweizerhof, K TI Nonlinear thermomechanical response of composite panels with continuous and terminated stiffeners SO TRENDS IN COMPUTATIONAL STRUCTURAL MECHANICS LA English DT Proceedings Paper CT International Conference on Trends in Computational Structural Mechanics CY MAY 20-23, 2001 CL SCHLOSS HOFEN, AUSTRIA DE composite panels; continuous and terminated stiffeners; nonlinear response; sensitivity analysis; response variability ID REDUCED BASIS TECHNIQUE AB A two-phase approach and a computational procedure are used for predicting the variability of the response of stiffened composite panels associated with variations in the geometric and material parameters of the structures. In the first phase, hierarchical sensitivity analysis is used to identify the major parameters that have the most effect on the response quantities of interest. In the second phase, the major parameters are taken to be fuzzy parameters, and a fuzzy set analysis is used to determine the range of variation of the response, associated with preselected variations in the major parameters. Numerical results are presented showing the variability of the response of panels with both continuous and terminated stiffeners associated with variations in the micro mechanical and geometric parameters. Both flat and curved panels are considered. C1 Old Dominion Univ, Langley Res Ctr, NASA, Ctr Adv Engn Environm, Hampton, VA 23681 USA. RP Noor, AK (reprint author), Old Dominion Univ, Langley Res Ctr, NASA, Ctr Adv Engn Environm, Hampton, VA 23681 USA. NR 15 TC 0 Z9 0 U1 0 U2 0 PU INT CENTER NUMERICAL METHODS ENGINEERING PI 08034 BARCELONA PA GRAN CAPITAN, S-N, CAMPUS NORTE UPC, MODULO C1, 08034 BARCELONA, SPAIN BN 84-89925-77-1 PY 2001 BP 348 EP 354 PG 7 WC Engineering, Civil; Mathematics, Applied; Mechanics; Materials Science, Composites SC Engineering; Mathematics; Mechanics; Materials Science GA BU83R UT WOS:000177158300033 ER PT J AU Pinel, SI Signer, HR Zaretsky, EV AF Pinel, SI Signer, HR Zaretsky, EV TI Design and operating characteristics of high-speed, small-bore cylindrical-roller bearings SO TRIBOLOGY TRANSACTIONS LA English DT Article; Proceedings Paper CT 55th Annual Meeting of the Society-of-Tribologists-and-Lubrication-Engineers CY MAY 07-11, 2000 CL NASHVILLE, TENNESSEE SP Soc Tribologists & Lubricat Engineers DE rolling-element bearings; roller bearings; engineering analysis and computing; life prediction methods; lubrication AB The computer program SHABERTH was used to analyze 35-nun-bore cylindrical roller bearings designed and manufactured for high-speed turbomachinery applications. Parametric tests of the bearings were conducted on a high-speed, high-temperature bearing tester and the results were compared with the computer predictions. Bearings with a channeled inner ring were lubricated through the inner ring, while bearings with a channeled outer ring were lubricated with oil jets. Tests were nm with and without enter-ring cooling. The predicted bearing life decreased with increasing speed because of increased contact stresses caused by centrifugal load Lower temperatures, less roller skidding and lower power losses,were obtained with channeled inner rings. Power losses calculated by the SHABERTH computer program correlated reasonably well with the lest results. The Parker formula for XCAV (used in SHABERTH as a measure of oil volume in the bearing cavity) needed to be adjusted to reflect the prevailing operating conditions. The XCAV formula will need to be further refined to reflect roller bearing lubrication, ring design, cage design, and location of the cage-controlling land. C1 Pinel Engn, Fullerton, CA 92634 USA. Signer Tech Serv, Fullerton, CA 92634 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Pinel, SI (reprint author), Pinel Engn, Fullerton, CA 92634 USA. NR 17 TC 1 Z9 1 U1 0 U2 4 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 1040-2004 J9 TRIBOL T JI Tribol. Trans. PD JAN PY 2001 VL 44 IS 1 BP 70 EP 78 DI 10.1080/10402000108982428 PG 9 WC Engineering, Mechanical SC Engineering GA 383TB UT WOS:000165898000010 ER PT B AU Fleurial, JP Snyder, GJ Patel, J Huang, CK Ryan, MA Averback, R Hill, C Chen, G AF Fleurial, JP Snyder, GJ Patel, J Huang, CK Ryan, MA Averback, R Hill, C Chen, G GP CHINA INDUSTRIAL ASSOCIATION OF POWER SOURCES CHINA INDUSTRIAL ASSOCIATION OF POWER SOURCES TI Solid-state power generation and cooling micro/nanodevices for distributed system architectures SO TWENTIETH INTERNATIONAL CONFERENCE ON THERMOELECTRICS, PROCEEDINGS LA English DT Proceedings Paper CT 20th International Conference on Thermoelectrics (ICT 2001) CY JUN 08-11, 2001 CL BEIJING, PEOPLES R CHINA SP China Ind Assoc Power Sources, Tianjin Lantian High-Tech Power Sources, Joint-Stock Co. Ltd, Int Thermoelect Soc, Tianjin Inst Power Sources ID CONDUCTIVITY AB Miniaturized solid-state devices for integrated thermal management packages and low power, high voltage, electrical power source systems are of interest for a variety of space and terrestrial applications. The National Aeronautics and Space Administration (NASA) and the Jet Propulsion Laboratory (JPL) have been planning the use of much smaller spacecrafts that will incorporate a variety of micro/nanodevices, such as microdetectors and microsensors, into miniature autonomous vehicles, such as microprobes and microrovers. High performance solid-state microcoolers and microgenerators based on thermoelectric, alpha-voltaic and thermionic energy conversion offer attractive solutions to the accelerating trend towards miniaturization of electronic components and distributed "system-on-a-chip" (SOAC) architectures where the functions of sense, compute, actuate, control, communicate and power are integrated. Novel thermoelectric micro/nanodevices that will provide the ability to handle much higher heat fluxes (thus resulting in high cooling power or electrical power densities), possess much faster response time as well as the possibility of generating high voltages under very small temperature differentials are being fabricated. After discussing the potential of thermoelectric and alpha-voltaic microdevices for SOAC architectures, this paper will report on our progress in electrochemical deposition of thermoelectric micro/nanoelements, thermoelectric and alpha-voltaic device microfabrication techniques as well as the electrical and thermal performance of the first devices. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fleurial, JP (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Snyder, G. Jeffrey/E-4453-2011; Snyder, G/I-2263-2015 OI Snyder, G. Jeffrey/0000-0003-1414-8682; NR 24 TC 9 Z9 14 U1 2 U2 4 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-7205-0 PY 2001 BP 24 EP 29 DI 10.1109/ICT.2001.979613 PG 6 WC Thermodynamics; Engineering, Electrical & Electronic; Physics, Applied SC Thermodynamics; Engineering; Physics GA BU02K UT WOS:000174745400005 ER PT B AU Caillat, T Fleurial, JP Snyder, GJ Borshchevsky, A AF Caillat, T Fleurial, JP Snyder, GJ Borshchevsky, A GP CHINA INDUSTRIAL ASSOCIATION OF POWER SOURCES CHINA INDUSTRIAL ASSOCIATION OF POWER SOURCES TI Development of high efficiency segmented thermoelectric unicouples SO TWENTIETH INTERNATIONAL CONFERENCE ON THERMOELECTRICS, PROCEEDINGS LA English DT Proceedings Paper CT 20th International Conference on Thermoelectrics (ICT 2001) CY JUN 08-11, 2001 CL BEIJING, PEOPLES R CHINA SP China Ind Assoc Power Sources, Tianjin Lantian High-Tech Power Sources, Joint-Stock Co. Ltd, Int Thermoelect Soc, Tianjin Inst Power Sources AB Highly efficient, segmented thermoelectric unicouples incorporating advanced thermoelectric materials with superior thermoelectric figures of merit are currently being developed at the Jet Propulsion Laboratory (JPL). These segmented unicouples include a combination of state-of-the-art thermoelectric materials based on Bi2Te3 and novel p-type Zn4Sb3, p-type CeFe4Sb12-based alloys and n-type CoSb3-based alloys developed at JPL. The maximum predicted thermal to electrical efficiency is about 15% for a hot-side temperature of 975K and a old-side temperature of about 300K. Various segmentations have been explored and several unicouples have been fabricated and tested. The set-up for testing these unicouples is described in this paper and some of the tests results reported. I-V curves have been generated for selected unicouples. The results show that experimental thermal to electrical efficiency values close to theoretical predicted values have been measured. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Caillat, T (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 277-207, Pasadena, CA 91109 USA. RI Snyder, G. Jeffrey/E-4453-2011; Snyder, G/I-2263-2015 OI Snyder, G. Jeffrey/0000-0003-1414-8682; NR 6 TC 30 Z9 34 U1 0 U2 6 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-7205-0 PY 2001 BP 282 EP 285 DI 10.1109/ICT.2001.979888 PG 4 WC Thermodynamics; Engineering, Electrical & Electronic; Physics, Applied SC Thermodynamics; Engineering; Physics GA BU02K UT WOS:000174745400068 ER PT S AU Li, JZ Ning, CZ AF Li, JZ Ning, CZ BE Chen, YK Knox, W Rodwell, M TI Dynamics of semiconductor quantum well laser under sub-terahertz electrical field modulation SO ULTRAFAST ELECTRONICS AND OPTOELECTRONICS, PROCEEDINGS SE OSA TRENDS IN OPTICS AND PHOTONICS LA English DT Proceedings Paper CT Meeting on Ultrafast Electronics and Optoelectronics CY JAN 10-12, 2001 CL LAKE TAHOE, NV SP Opt Soc Amer, IEEE/LEOS Lasers & Electro Opt Soc AB Dynamic simulations are presented for GaAs quantum well laser under inplane sub-terahertz electric field modulation. The active medium is described by a hydrodynamic model including nonlinear optical gain and plasma heating. Optimization schemes are discussed for future ultrafast optoelectronic applications. (C)2001 Optical Society of America. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Li, JZ (reprint author), NASA, Ames Res Ctr, M-S T27A-1, Moffett Field, CA 94035 USA. NR 13 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMERICA PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1094-5695 BN 1-55752-659-1 J9 OSA TRENDS OPT PHOTO PY 2001 VL 49 BP 93 EP 99 PG 7 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA BU62Y UT WOS:000176557200023 ER PT S AU Ning, CZ Goorjian, P AF Ning, CZ Goorjian, P BE Chen, YK Knox, W Rodwell, M TI Ultrafast beam switching using coupled VCSELs SO ULTRAFAST ELECTRONICS AND OPTOELECTRONICS, PROCEEDINGS SE OSA TRENDS IN OPTICS AND PHOTONICS LA English DT Proceedings Paper CT Meeting on Ultrafast Electronics and Optoelectronics CY JAN 10-12, 2001 CL LAKE TAHOE, NV SP Opt Soc Amer, IEEE/LEOS Lasers & Electro Opt Soc ID SURFACE-EMITTING LASERS C1 NASA, Ames Res Ctr, Computat Quantum Optoelect, Moffett Field, CA 94035 USA. RP Ning, CZ (reprint author), NASA, Ames Res Ctr, Computat Quantum Optoelect, Mail Stop T27A-1, Moffett Field, CA 94035 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMERICA PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1094-5695 BN 1-55752-659-1 J9 OSA TRENDS OPT PHOTO PY 2001 VL 49 BP 171 EP 173 PG 3 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA BU62Y UT WOS:000176557200039 ER PT S AU Hogg, RW Rankin, AL McIlenry, MC Helmick, DM Bergh, CF Roumeliotis, SI Matthies, L AF Hogg, RW Rankin, AL McIlenry, MC Helmick, DM Bergh, CF Roumeliotis, SI Matthies, L BE Gerhart, GR Shoemaker, CM TI Sensors and algorithms for small robot leader/follower behavior SO UNMANNED GROUND VEHICLE TECHNOLOGY III SE Proceedings of SPIE LA English DT Proceedings Paper CT Conference on Unmanned Ground Vehicle Technology III CY APR 16-17, 2001 CL ORLANDO, FL SP SPIE DE mobile robots; path following; leader/follower; pure pursuit; localization; Kalman filtering AB Tracked mobile robots in the 20 kg size class are under development for applications in urban reconnaissance. For efficient deployment, it is desirable for teams of robots to be able to automatically execute leader/follower behaviors, with one or more followers tracking the path taken by a leader. The key challenges to enabling such a capability are (1) to develop sensor packages for such small robots that can accurately determine the path of the leader and (2) to develop path-following algorithms for the subsequent robots. To date, we have integrated gyros, accelerometers, compass/inclinometers, odometry, and differential GPS into an effective sensing package for a small urban robot. This paper describes the sensor package, sensor processing algorithm, and path tracking algorithm we have developed for the leader/follower problem in small robots and shows the results of performance characterization of the system. We also document pragmatic lessons learned about design, construction, and electromagnetic interference issues particular to the performance of state sensors on small robots. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 125-209, Pasadena, CA 91109 USA. EM larry.matthies@jpl.nasa.gov NR 23 TC 0 Z9 0 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4059-0 J9 PROC SPIE PY 2001 VL 4364 BP 72 EP 85 DI 10.1117/12.439967 PG 14 WC Computer Science, Artificial Intelligence; Robotics; Transportation Science & Technology SC Computer Science; Robotics; Transportation GA BT28L UT WOS:000172533400009 ER PT S AU Fleck, B AF Fleck, B CA Solar Orbiter Study Team BE Siegmund, OHW Fineschi, S Gummin, MA TI Solar Orbiter - A high resolution mission to the Sun and inner heliosphere SO UV/EUV AND VISIBLE SPACE INSTRUMENTATION FOR ASTRONOMY AND SOLAR PHYSICS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on UV/EUV and Visible Space Instrumentation for Astronomy and Solar Physics CY AUG 01-02, 2001 CL SAN DIEGO, CA SP SPIE DE Sun; heliosphere; space plasma physics; UV/EUV; instrumentation AB The key mission objective of the Solar Orbiter is to study the Sun from close-up (45 solar radii, or 0.21 AU) in an orbit tuned to solar rotation in order to examine the solar surface and the space above from a co-rotating vantage point at high spatial resolution. Solar Orbiter will also provide images of the Sun's polar regions from heliographic latitudes as high as 38degrees. The strawman payload encompasses two instrument packages: Solar remote-sensing instruments: EUV full-sun and high resolution imager, high-resolution EUV spectrometer, high-resolution and full-sun visible light telescope and magnetograph, EUV and visible-light coronagraphs, radiometers. Heliospheric instruments: solar wind analyzer, radio and plasma wave analyser, magnetometer, energetic particle detectors, interplanetary dust detector, neutral particle detector, solar neutron detector. To reach its novel orbit, Solar Orbiter will make use of low-thrust solar electric propulsion (SEP) interleaved by Earth and Venus gravity assists. Solar Orbiter was selected by ESA's Science Programme Committee (SPC) in October 2000 as a Flexi-mission, to be implemented after the BepiColombo cornerstone mission to Mercury before 2013. This paper summarizes the science to be addressed with the Solar Orbiter, followed by brief descriptions of the strawman payload, the mission profile, amd the spacecraft and ground segment designs. C1 NASA, Goddard Space Flight Ctr, ESA, Dept Space Sci, Greenbelt, MD 20771 USA. RP Fleck, B (reprint author), NASA, Goddard Space Flight Ctr, ESA, Dept Space Sci, Mailcode 682-3, Greenbelt, MD 20771 USA. RI Fleck, Bernhard/C-9520-2012 NR 5 TC 6 Z9 6 U1 0 U2 2 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4212-7 J9 P SOC PHOTO-OPT INS PY 2001 VL 4498 BP 1 EP 15 DI 10.1117/12.450046 PG 15 WC Engineering, Aerospace; Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Engineering; Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BT90U UT WOS:000174396500001 ER PT S AU West, EA Porter, JG Davis, JM Gary, GA Adams, M Smith, S Hraba, JF AF West, EA Porter, JG Davis, JM Gary, GA Adams, M Smith, S Hraba, JF BE Siegmund, OHW Fineschi, S Gummin, MA TI Optical characteristics of the Marshall Space Flight Center solar ultraviolet magnetograph SO UV/EUV AND VISIBLE SPACE INSTRUMENTATION FOR ASTRONOMY AND SOLAR PHYSICS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on UV/EUV and Visible Space Instrumentation for Astronomy and Solar Physics CY AUG 01-02, 2001 CL SAN DIEGO, CA SP SPIE ID MAXIMUM MISSION; SPECTROMETER; POLARIMETER AB This paper will describe the scientific objectives of the Marshall Space Flight Center (MSFC) Solar Ultraviolet Magnetograph Investigation (SUMI) and the optical components that have been developed to meet those objectives. In order to test the scientific feasibility of measuring magnetic fields in the UV, a sounding rocket payload is being developed. This paper will discuss: (1) the scientific measurements that will be made by the SUMI sounding rocket program, (2) how the optics have been optimized for simultaneous measurements of two magnetic lines CIV (1550 A) and MgII (2800 A), and (3) the optical, reflectance, transmission and polarization measurements that have been made on the SUMI telescope mirrors and polarimeter. C1 NASA, George C Marshall Space Flight Ctr, NSSTC, Huntsville, AL 35812 USA. RP West, EA (reprint author), NASA, George C Marshall Space Flight Ctr, NSSTC, Huntsville, AL 35812 USA. NR 12 TC 4 Z9 4 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4212-7 J9 P SOC PHOTO-OPT INS PY 2001 VL 4498 BP 101 EP 110 DI 10.1117/12.450050 PG 10 WC Engineering, Aerospace; Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Engineering; Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BT90U UT WOS:000174396500010 ER PT S AU Thomas, RJ Davila, JM AF Thomas, RJ Davila, JM BE Siegmund, OHW Fineschi, S Gummin, MA TI EUNIS: a solar EUV normal-incidence spectrometer SO UV/EUV AND VISIBLE SPACE INSTRUMENTATION FOR ASTRONOMY AND SOLAR PHYSICS SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on UV/EUV and Visible Space Instrumentation for Astronomy and Solar Physics CY AUG 01-02, 2001 CL SAN DIEGO, CA SP SPIE DE solar; corona; EUV; spectrometer ID EXTREME-ULTRAVIOLET SPECTRA; ACTIVE-REGION; PERFORMANCE AB GSFC is in the process of assembling a solar EUV Normal-Incidence Spectrometer called EUNIS, to be flown as a sounding rocket payload. This instrument builds on the many technical innovations pioneered by our highly successful SERTS experiment over its past ten flights. The new design has improved spatial and spectral resolutions, as well as 100 times greater sensitivity, permitting EUV spectroscopy with a temporal resolution near I second for the first time ever. To achieve such high time cadence, a novel Active-Pixel-Sensor detector is being developed as a key component of our design. The high sensitivity of EUNIS allows entirely new studies of transient coronal phenomena, such as the rapid loop dynamics seen by TRACE, and searches for non-thermal motions indicative of magnetic reconnection or wave heating. The increased sensitivity also permits useful EUV spectra at heights of 2-3 solar radii above the limb, where the transition between the static corona and the solar wind might occur. In addition, the new design features two independent optical systems, more than doubling the spectral bandwidth covered on each flight. Its 300-370Angstrom bandpass includes He II 304Angstrom and strong lines from Fe XI-XVI, extending the current SERTS range of 300-355Angstrom to further improve our ongoing series of calibration under-flights for SOHO/CDS and EIT. The second bandpass of 170-205Angstrom has a sequence of very strong Fe IX-XIII lines, and allows under-flight support for two more channels on SOHO/EIT, two channels on TRACE, one on Solar-B/EIS, and all four channels on the STEREO/EUVI instrument. First flight of the new EUNIS payload is presently scheduled for 2002 October. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Thomas, RJ (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 8 TC 8 Z9 8 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4212-7 J9 P SOC PHOTO-OPT INS PY 2001 VL 4498 BP 161 EP 172 DI 10.1117/12.450072 PG 12 WC Engineering, Aerospace; Astronomy & Astrophysics; Instruments & Instrumentation; Optics SC Engineering; Astronomy & Astrophysics; Instruments & Instrumentation; Optics GA BT90U UT WOS:000174396500016 ER PT S AU Rabbitt, RD Boyle, R Highstein, SM AF Rabbitt, RD Boyle, R Highstein, SM BE Goebel, J Highstein, SM TI Physiology of the semicircular canals after surgical plugging SO VESTIBULAR LABYRINTH IN HEALTH AND DISEASE SE ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article; Proceedings Paper CT Conference on the Vestibular Labyrinth in Health and Disease CY NOV 16-18, 2000 CL ST LOUIS, MISSOURI SP Natl Inst Deafness & Other Commun Disorders, NASA, Natl Sci Fdn, Deafness Res Fdn, Neurocom Int Inc, Micromed Technologies Inc, Nicolet Biomed, Alcon Labs DE vestibular; biomechanics; afferent; BPPV; endolymph; occlusion ID VESTIBULOOCULAR REFLEX; SQUIRREL-MONKEY; OPSANUS-TAU; VESTIBULAR LABYRINTH; RESTING DISCHARGE; RESPONSE DYNAMICS; INACTIVATION; TOADFISH; NYSTAGMUS; RECOVERY AB Inactivation of individual semicircular canals by surgical occlusion (plugging) of the slender duct has been used in basic studies to elucidate the role of individual canal inputs to vestibular-mediated control systems and in clinical applications to treat certain vestibular disorders. The procedure has been shown to be highly effective in blocking sensitivity of individual canals, at least for moderate angular motion stimuli. Effectiveness does not extend to stimuli involving high accelerations where a residual response persists even after complete occlusion of the duct. The residual can be quite large at high-stimulus frequencies where sensitivity to angular motion approaches that of patent canals. The overall physiological effect of canal plugging is reported here in terms of the frequency-dependent attenuation in gain and phase shift of primary afferents. Plug-canal responses are quantitatively described in terms of biomechanics of the deformable labyrinth. C1 Univ Utah, Dept Bioengn, MEB 2480, Salt Lake City, UT 84112 USA. NASA, Ames Ctr Bioinformat, Moffett Field, CA 94035 USA. Washington Univ, Dept Otolaryngol, St Louis, MO 63110 USA. Washington Univ, Dept Neurobiol, St Louis, MO 63110 USA. Marine Biol Lab, Woods Hole, MA 02543 USA. RP Rabbitt, RD (reprint author), Univ Utah, Dept Bioengn, MEB 2480, 50 S Cent Campus Dr, Salt Lake City, UT 84112 USA. FU NIDCD NIH HHS [DC-01837] NR 30 TC 18 Z9 19 U1 1 U2 3 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 EAST 63RD ST, NEW YORK, NY 10021 USA SN 0077-8923 BN 1-57331-289-4 J9 ANN NY ACAD SCI JI Ann.NY Acad.Sci. PY 2001 VL 942 BP 274 EP 286 PG 13 WC Multidisciplinary Sciences; Otorhinolaryngology SC Science & Technology - Other Topics; Otorhinolaryngology GA BT31Q UT WOS:000172619200023 PM 11710469 ER PT S AU Rabbitt, RD Yamauchi, AM Boyle, R Highstein, SM AF Rabbitt, RD Yamauchi, AM Boyle, R Highstein, SM BE Goebel, J Highstein, SM TI How endolymph pressure modulates semicircular canal primary afferent discharge SO VESTIBULAR LABYRINTH IN HEALTH AND DISEASE SE ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article; Proceedings Paper CT Conference on the Vestibular Labyrinth in Health and Disease CY NOV 16-18, 2000 CL ST LOUIS, MISSOURI SP Natl Inst Deafness & Other Commun Disorders, NASA, Natl Sci Fdn, Deafness Res Fdn, Neurocom Int Inc, Micromed Technologies Inc, Nicolet Biomed, Alcon Labs DE mechano-transduction; endolymphatic hydrops; vestibular mechanics ID VESTIBULAR LABYRINTH; OPSANUS-TAU; TOADFISH AB Histological observation of endolymphatic hydrops in subjects suffering from Meniere's disease/syndrome and the presence of vestibular symptoms in experimentally induced endolymphatic hydrops have led to considerable debate regarding the potential role of inner-ear pressure. Could a condition influencing endolymphatic volume regulation lead to transient changes in translabyrinthine pressure sufficiently large to alter primary afferent discharge rates? To investigate this question we built a highly sensitive laser-based pressure sensor and recorded endolymphatic pressure modulations within the horizontal semicircular canal ampulla in response to mechanical stimuli for simple head rotation and controlled volume injection. The most sensitive primary afferents responded to changes in endolymph pressures as low as 0.005 Pa (re: perilymph) - a pressure considerably lower than that observed in most experimentally induced hydropic conditions. This threshold pressure was generated by a similar to 25 picoliter volume injection stimulus. Semicircular canal afferent responses to endolymphatic pressure can be explained on the basis of pressure-induced hydrops, which causes dilation of the ampulla, deformation of the cupula, hair bundle movement, and afferent discharge. Primary afferent responses to maintained stimuli were transient in nature and recovered to pre-stimulus background discharge rates following a period of adaptation. Results demonstrate that the semicircular canals are indeed sensitive to small changes in translabyrinthine pressure in addition to head-movement-related changes in transcupular pressure. C1 Univ Utah, Dept Bioengn, Salt Lake City, UT 84112 USA. NASA, Ames Ctr Bioinformat, Moffett Field, CA 94035 USA. Washington Univ, Dept Otolaryngol, St Louis, MO 63110 USA. Washington Univ, Dept Neurobiol, St Louis, MO 63110 USA. Marine Biol Lab, Woods Hole, MA 02543 USA. RP Rabbitt, RD (reprint author), Univ Utah, Dept Bioengn, 2480 MEM,50 S Cent Campus Dr, Salt Lake City, UT 84112 USA. FU NIDCD NIH HHS [DC-01837] NR 13 TC 9 Z9 10 U1 0 U2 4 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 EAST 63RD ST, NEW YORK, NY 10021 USA SN 0077-8923 BN 1-57331-289-4 J9 ANN NY ACAD SCI JI Ann.NY Acad.Sci. PY 2001 VL 942 BP 313 EP 321 PG 9 WC Multidisciplinary Sciences; Otorhinolaryngology SC Science & Technology - Other Topics; Otorhinolaryngology GA BT31Q UT WOS:000172619200027 PM 11710473 ER PT S AU Boyle, R AF Boyle, R BE Goebel, J Highstein, SM TI Vestibulospinal control of reflex and voluntary head movement SO VESTIBULAR LABYRINTH IN HEALTH AND DISEASE SE Annals of the New York Academy of Sciences LA English DT Article; Proceedings Paper CT Conference on the Vestibular Labyrinth in Health and Disease CY NOV 16-18, 2000 CL ST LOUIS, MO SP Natl Inst Deafness & Other Commun Disorders, NASA, Natl Sci Fdn, Deafness Res Fdn, Neurocom Int Inc, Micromed Technologies Inc, Nicolet Biomed, Alcon Labs ID CERVICAL SPINAL-CORD; ALERT SQUIRREL-MONKEY; VESTIBULAR NEURONS; PHYSIOLOGICAL-CHARACTERISTICS; VESTIBULOCOLLIC NEURONS; NECK MOTONEURONS; TRACT CELLS; CAT; MORPHOLOGY; AXONS AB Secondary canal-related vestibulospinal neurons respond to an externally applied movement of the head in the form of a firing rate modulation that encodes the angular velocity of the movement, and reflects in large part the input "head velocity in space" signal carried by the semicircular canal afferents. In addition to the head velocity signal, the vestibulospinal neurons can carry a more processed signal that includes eye position or eye velocity, or both (see Boyle(1) on ref. list). To understand the control signals used by the central vestibular pathways in the generation of reflex head stabilization, such as the vestibulocollic reflex (VCR), and the maintenance of head posture, it is essential to record directly from identified vestibulospinal neurons projecting to the cervical spinal segments in the alert animal. The present report discusses two key features of the primate vestibulospinal system. First, the termination morphology of vestibulospinal axons in the cervical segments of the spinal cord is described to lay the structural basis of vestibulospinal control of head/neck posture and movement. And second, the head movement signal content carried by the same class of secondary vestibulospinal neurons during the actual execution of the VCR and during self-generated, or active, rapid head movements is presented. C1 NASA, Ames Res Ctr, Ctr Bioinformat, Moffett Field, CA 94035 USA. RP Boyle, R (reprint author), NASA, Ames Res Ctr, Ctr Bioinformat, M-S 239-11, Moffett Field, CA 94035 USA. EM rboyle@mail.arc.nasa.gov FU NEI NIH HHS [EY08-041]; NIDCD NIH HHS [DC02072]; NINDS NIH HHS [NS27050] NR 39 TC 16 Z9 16 U1 0 U2 2 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 EAST 63RD ST, NEW YORK, NY 10021 USA SN 0077-8923 BN 1-57331-290-8; 1-57331-289-4 J9 ANN NY ACAD SCI JI Ann.NY Acad.Sci. PY 2001 VL 942 BP 364 EP 380 PG 17 WC Multidisciplinary Sciences; Otorhinolaryngology SC Science & Technology - Other Topics; Otorhinolaryngology GA BT31Q UT WOS:000172619200031 PM 11710478 ER PT B AU Pravdo, SH AF Pravdo, SH BE Brunner, RJ Djorjovski, SG Szalay, AS TI Solar system surveys SO VIRTUAL OBSERVATORIES OF THE FUTURE, PROCEEDINGS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Virtual Observatories of the Future CY JUN 13-16, 2000 CL CALIF INST TECHNOL, PASADENA, CA SP Natl Sci Fdn, Natl Aeronaut & Space Adm, Sun Microsyst & Microsoft Res HO CALIF INST TECHNOL ID EARTH AB Astronomical data is a necessary starting point for a virtual observatory. Solar system surveys provide extensive sky coverage and vast amounts of celestial images. We list and briefly describe the ongoing NEO programs. One of these, the Near-Earth Asteroid Tracking (NEAT) program, archives its data, making it available for the science community. A small investment now can ensure that these data are available in the future, not only for the uses described below, but also for uses not yet envisioned. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Pravdo, SH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-057-9 J9 ASTR SOC P PY 2001 VL 225 BP 118 EP 124 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS48T UT WOS:000170040800019 ER PT B AU McGlynn, TA McDonald, LM White, NE AF McGlynn, TA McDonald, LM White, NE BE Brunner, RJ Djorjovski, SG Szalay, AS TI Sky View: Experiences building a virtual telescope SO VIRTUAL OBSERVATORIES OF THE FUTURE, PROCEEDINGS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Virtual Observatories of the Future CY JUN 13-16, 2000 CL CALIF INST TECHNOL, PASADENA, CA SP Natl Sci Fdn, Natl Aeronaut & Space Adm, Sun Microsyst & Microsoft Res HO CALIF INST TECHNOL AB During the past decade the SkyView virtual telescope has provided a single unified interface with which astronomers - and the general public - can access data from all wavelengths. SkyView has addressed many of the issues that face the National Virtual Observatory (NVO) effort: supporting science that spans wavelength regimes; handling very heterogeneous data sets in a consistent fashion, and catering to a very diverse set of users. In this paper we discuss some of the lessons we have learned building and running SkyView. C1 Univ Space Res Assoc, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP McGlynn, TA (reprint author), Univ Space Res Assoc, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 8 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-057-9 J9 ASTR SOC P PY 2001 VL 225 BP 125 EP 129 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS48T UT WOS:000170040800020 ER PT B AU Dimitoglou, G Duarte, LS AF Dimitoglou, G Duarte, LS BE Brunner, RJ Djorjovski, SG Szalay, AS TI The SOHO Data and Information System SO VIRTUAL OBSERVATORIES OF THE FUTURE, PROCEEDINGS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Virtual Observatories of the Future CY JUN 13-16, 2000 CL CALIF INST TECHNOL, PASADENA, CA SP Natl Sci Fdn, Natl Aeronaut & Space Adm, Sun Microsyst & Microsoft Res HO CALIF INST TECHNOL AB Since the early stages of the mission, SOHO teams employed WWW-based technologies to provide tools for mission planning, data analysis and public outreach support. Today, this collection of tools can be viewed as an integrated data and information system that plays a significant role in science operations and data distribution. This paper is an overview of some of the components, functions, products and services provided by the SOHO Data and Information System. C1 NASA, Goddard Space Flight Ctr, Div Space Sci, Greenbelt, MD 20771 USA. RP Dimitoglou, G (reprint author), NASA, Goddard Space Flight Ctr, Div Space Sci, Code 682-3, Greenbelt, MD 20771 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-057-9 J9 ASTR SOC P PY 2001 VL 225 BP 173 EP 175 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS48T UT WOS:000170040800029 ER PT B AU Jacob, JC Husman, LE AF Jacob, JC Husman, LE BE Brunner, RJ Djorjovski, SG Szalay, AS TI Large-scale visualization of digital sky surveys SO VIRTUAL OBSERVATORIES OF THE FUTURE, PROCEEDINGS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Virtual Observatories of the Future CY JUN 13-16, 2000 CL CALIF INST TECHNOL, PASADENA, CA SP Natl Sci Fdn, Natl Aeronaut & Space Adm, Sun Microsyst & Microsoft Res HO CALIF INST TECHNOL AB Designed and developed within JPL/Caltech's supercomputing and visualization environment, the virtual observatory software described in this paper permits high performance visualization and analysis of large sky images and catalogs. Functionality includes parallel generation of large sky image mosaics and synthetic maps from catalogs, techniques for interactive exploration of large images on workstation or special high resolution displays, image enhancement features, catalog viewing, catalog to image relation, and run-time compositing of multiresolution datasets. The tools and technologies being developed are intended to be components of the National (and eventually Global) Virtual Observatory effort, which will federate and provide seamless access to a wide variety of geographically distributed, multi-terabyte datasets. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jacob, JC (reprint author), CALTECH, Jet Prop Lab, MS 126-234,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-057-9 J9 ASTR SOC P PY 2001 VL 225 BP 291 EP 296 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS48T UT WOS:000170040800051 ER PT B AU Cheung, CY AF Cheung, CY BE Brunner, RJ Djorjovski, SG Szalay, AS TI Distributed archives interoperability SO VIRTUAL OBSERVATORIES OF THE FUTURE, PROCEEDINGS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Virtual Observatories of the Future CY JUN 13-16, 2000 CL CALIF INST TECHNOL, PASADENA, CA SP Natl Sci Fdn, Natl Aeronaut & Space Adm, Sun Microsyst & Microsoft Res HO CALIF INST TECHNOL AB Interoperability is an inherent goal of the Virtual Observatory of the Future. It describes the state when the distributed, diverse and multispectral astrophysical data and computational resources are linked together into a cohesive functional unit, enabling systematic data exploration and discoveries. This paper summarizes the technical issues and challenges to be addressed by both the astronomy and computer science communities before this goal can be realized. C1 NASA, Goddard Space Flight Ctr, Astrophys Data Facil, Greenbelt, MD 20771 USA. RP Cheung, CY (reprint author), NASA, Goddard Space Flight Ctr, Astrophys Data Facil, Greenbelt, MD 20771 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-057-9 J9 ASTR SOC P PY 2001 VL 225 BP 316 EP 322 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS48T UT WOS:000170040800054 ER PT B AU Borne, KD AF Borne, KD BE Brunner, RJ Djorjovski, SG Szalay, AS TI Science user scenarios for a VO Design Reference Mission SO VIRTUAL OBSERVATORIES OF THE FUTURE, PROCEEDINGS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Virtual Observatories of the Future CY JUN 13-16, 2000 CL CALIF INST TECHNOL, PASADENA, CA SP Natl Sci Fdn, Natl Aeronaut & Space Adm, Sun Microsyst & Microsoft Res HO CALIF INST TECHNOL ID DISCOVERY; GALAXIES AB The knowledge discovery potential of the new large astronomical databases is vast. When these are used in conjunction with the rich legacy data archives, the opportunities for scientific discovery multiply rapidly. A Virtual Observatory (VO) framework will enable transparent and efficient access, search, retrieval, and visualization of data across multiple data repositories, which are generally heterogeneous and distributed. Aspects of data mining that apply to a variety of science user scenarios with a VO are reviewed. The development of a VO should address the data mining needs of various astronomical research constituencies. By way of example, two user scenarios are presented which invoke applications and linkages of data across the catalog and image domains in order to address specific astrophysics research problems. These illustrate a subset of the desired capabilities and power of the VO, and as such they represent potential components of a VO Design Reference Mission. C1 NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Borne, KD (reprint author), NASA, Goddard Space Flight Ctr, Raytheon ITSS, Code 631, Greenbelt, MD 20771 USA. NR 10 TC 2 Z9 2 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-057-9 J9 ASTR SOC P PY 2001 VL 225 BP 333 EP 336 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS48T UT WOS:000170040800057 ER PT B AU Scargle, JD Crutchfield, JP Glymour, C Hewett, R AF Scargle, JD Crutchfield, JP Glymour, C Hewett, R BE Brunner, RJ Djorjovski, SG Szalay, AS TI A processing automaton for intensive data SO VIRTUAL OBSERVATORIES OF THE FUTURE, PROCEEDINGS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Conference on Virtual Observatories of the Future CY JUN 13-16, 2000 CL CALIF INST TECHNOL, PASADENA, CA SP Natl Sci Fdn, Natl Aeronaut & Space Adm, Sun Microsyst & Microsoft Res HO CALIF INST TECHNOL ID BAYESIAN BLOCKS AB Automated discovery of new astronomical phenomena and extraction of knowledge about familiar ones will be important for any Virtual Observatory. An autonomous data processor - transforming raw data streams into intelligible structures and then recognizing patterns in the structures - can achieve this grand objective within a restricted but broad scope, namely measurements of the intensity of a physical quantity distributed over a fixed domain. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Scargle, JD (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 11 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-057-9 J9 ASTR SOC P PY 2001 VL 225 BP 337 EP 340 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS48T UT WOS:000170040800058 ER PT S AU Kao, D Pang, A AF Kao, D Pang, A BE Erbacher, RF Chen, PC Roberts, JC Wittenbrink, CM Grohn, M TI On animating 2D velocity fields SO VISUAL DATA EXPLORATION AND ANALYSIS VIII SE Proceedings of SPIE LA English DT Proceedings Paper CT 8th Meeting of the Visual Data Exploration and Analysis Conference CY JAN 22-23, 2001 CL SAN JOSE, CA SP Soc Imaging Sci & Technol, SPIE DE texture advection; streamlines; droplets; color table animation; LIC; texture mapping; flow field ID LINE INTEGRAL CONVOLUTION AB A velocity field, even one that represents a steady state flow, implies a dynamical system. Animated velocity fields is an important tool in understanding such complex phenomena. This paper looks at a number of techniques that animate velocity fields and propose two new alternatives. These are texture advection and streamline cycling. The common theme among these techniques is the use of advection on some texture to generate a realistic anima ion of the velocity field. Texture synthesis and selection for these methods are presented. Strengths and weaknesses of the techniques are also discussed in conjunctions with several examples. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. EM davidkao@nas.nasa.gov; pang@cse.ucsc.edu NR 12 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3980-0 J9 PROC SPIE PY 2001 VL 4302 BP 41 EP 48 DI 10.1117/12.424942 PG 8 WC Optics; Imaging Science & Photographic Technology SC Optics; Imaging Science & Photographic Technology GA BS55Q UT WOS:000170315300005 ER PT S AU Jobson, DJ Rahman, ZU Woodell, GA AF Jobson, DJ Rahman, ZU Woodell, GA BE Park, SK Rahman, ZU Schowengerdt, RA TI The spatial aspect of color and scientific implications of retinex image processing SO VISUAL INFORMATION PROCESSING X SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 10th Visual Information Processing Conference CY APR 19-20, 2001 CL ORLANDO, FL SP SPIE ID VISION AB The history of the spatial aspect of color perception is reviewed in order to lay a foundation for the discussion of retinex image processing. While retinex computations were originally conceived as a model for color constancy in human vision, the impact on local contrast and lightness is even more pronounced than the compensation for changes in the spectral distribution of scene illuminants. In the multiscale retinex with color restoration (MSRCR), the goal of the computation is fidelity to the direct observation of scenes. The primary visual shortcoming of the recorded image is that dark zones such as shadow zones are perceived with much lower contrast and lightness than for the direct viewing of scenes. Extensive development and testing of the MSRCR led us to form several hypotheses about imaging which appear to be basic and general in nature. These are: (1) the linear representation of the image is not usually a good visual representation, (2) retinex image enhancements tend to approach a statistical ideal which suggests the existence of a canonical "visual image", and (3) the mathematical form of the MSRCR suggests a deterministic definition of visual information which is the log of the spectral and spatial context ratios for any given image. These ideas imply that the imaging process should be thought of, not as a replication process whose goal is minimal distortion, but rather as a profound non-linear transformation process whose goal is a statistical ideal visual representation. These insights suggest new directions for practical advances in bringing higher levels of visual intelligence to the world of computing. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Jobson, DJ (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 13 TC 7 Z9 7 U1 0 U2 1 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4083-3 J9 P SOC PHOTO-OPT INS PY 2001 VL 4388 BP 117 EP 128 DI 10.1117/12.438249 PG 12 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic; Remote Sensing; Optics; Imaging Science & Photographic Technology SC Computer Science; Engineering; Remote Sensing; Optics; Imaging Science & Photographic Technology GA BT16L UT WOS:000172293400014 ER PT S AU Kao, D Dungan, JL Pang, A AF Kao, D Dungan, JL Pang, A BE Ertl, T Joy, K Varshney, A TI Visualizing 2D probability distributions from EOS satellite image-derived data sets: A case study SO VISUALIZATION 2001, PROCEEDINGS SE IEEE CONFERENCE ON VISUALIZATION LA English DT Proceedings Paper CT IEEE Visualization Conference CY OCT 21-26, 2001 CL SAN DIEGO, CA SP IEEE Comp Soc, Tech Comm Visualizat & Graph, ACM SIGGRAPH DE uncertainty; probability density function; geostatistics; conditional simulation; data assimilation ID AREA AB Maps of biophysical and geophysical variables using Earth Observing System (EOS) satellite image data are an important component of Earth science. These maps have a single value derived at every grid cell and standard techniques are used to visualize them. Current tools fall short, however, when it is necessary to describe a distribution of values at each grid cell. Distributions may represent a frequency of occurrence over time, frequency of occurrence from multiple runs of an ensemble forecast or possible values from an uncertainty model. We identify these "distribution data sets" and present a case study to visualize such 2D distributions. Distribution data sets are different from multivariate data sets in the sense that the values are for a single variable instead of multiple variables. Data for this case study consist,, of multiple realizations of percent forest cover, generated using a geostatistical technique that combines ground measurements and satellite imagery to model uncertainty about forest cover. We present two general approaches for analyzing and visualizing such data sets. The first is a pixel-wise analysis of the probability density functions for the 2D image while the second is an analysis of features identified within the image. Such pixel-wise and feature-wise views will give Earth scientists a more complete understanding of distribution data sets, See www.cse.ucsc.edu/research/avis/nasa_is for additional information. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kao, D (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI Dungan, Jennifer/G-9921-2016 OI Dungan, Jennifer/0000-0002-4863-1616 NR 15 TC 17 Z9 18 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1070-2385 BN 0-7803-7200-X J9 IEEE VISUAL PY 2001 BP 457 EP 460 DI 10.1109/VISUAL.2001.964550 PG 4 WC Computer Science, Artificial Intelligence; Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA BT78K UT WOS:000174051300061 ER PT S AU Severance, K Brewster, P Lazos, B Keefe, D AF Severance, K Brewster, P Lazos, B Keefe, D BE Ertl, T Joy, K Varshney, A TI Wind tunnel data fusion and immersive visualization: A case study SO VISUALIZATION 2001, PROCEEDINGS SE IEEE CONFERENCE ON VISUALIZATION LA English DT Proceedings Paper CT IEEE Visualization Conference CY OCT 21-26, 2001 CL SAN DIEGO, CA SP IEEE Comp Soc, Tech Comm Visualizat & Graph, ACM SIGGRAPH DE data fusion; photogrammetry; line integral convolution; reconstruction; oil flow; Particle Image Velocimetry; wind tunnel; landing gear; texture mapping.; image-based rendering; VRML AB This case study describes the process of fusing the data from several wind tunnel experiments into a single coherent visualization. Each experiment was conducted independently and was designed to explore different now features around airplane landing gear. In the past, it would have been very difficult to correlate results from the different experiments. However. with a single 3-D visualization representing the fusion of the three experiments, significant insight into the composite flowfield was observed that would have been extremely difficult to obtain by studying its component parts. The results are even more compelling when viewed in an immersive environment. C1 NASA, Langley Res Ctr, Hampton, VA 23365 USA. RP Severance, K (reprint author), NASA, Langley Res Ctr, Hampton, VA 23365 USA. NR 11 TC 1 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1070-2385 BN 0-7803-7200-X J9 IEEE VISUAL PY 2001 BP 505 EP 508 DI 10.1109/VISUAL.2001.964563 PG 4 WC Computer Science, Artificial Intelligence; Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA BT78K UT WOS:000174051300073 ER PT S AU Huang, NE AF Huang, NE BE Szu, HH Donoho, DL Lohmann, AW Campbell, WJ Buss, JR TI Review of Empirical Mode Decomposition SO WAVELET APPLICATIONS VIII SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 8th Annual Conference on Wavelet Applications CY APR 18-20, 2001 CL ORLANDO, FL SP SPIE ID HILBERT SPECTRUM AB The newly developed Empirical Mode Decomposition (EMD) and the Hilbert Spectral Analysis method will be reviewed. The EMD is an adaptive decomposition with which any complicated data set can be decomposed into a finite and often small number of Intrinsic Mode Functions. Example of application on the chirp signal form the bat is given to illustrate the potential of the new method. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Huang, NE (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 9 TC 12 Z9 15 U1 1 U2 8 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4086-8 J9 P SOC PHOTO-OPT INS PY 2001 VL 4391 BP 71 EP 80 DI 10.1117/12.421232 PG 10 WC Engineering, Electrical & Electronic; Optics; Imaging Science & Photographic Technology SC Engineering; Optics; Imaging Science & Photographic Technology GA BS47F UT WOS:000169942000008 ER PT S AU Kiang, RK Kyle, FL AF Kiang, RK Kyle, FL BE Szu, HH Donoho, DL Lohmann, AW Campbell, WJ Buss, JR TI A time-frequency analysis of the effects of solar activities on tropospheric thermodynamics SO WAVELET APPLICATIONS VIII SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT 8th Annual Conference on Wavelet Applications CY APR 18-20, 2001 CL ORLANDO, FL SP SPIE ID FLUX AB Whether the Sun has significantly influenced the climate during the last century has been under extensive debates for almost two decades. Since the solar irradiance varies very little in a solar cycle, it is puzzling that some geophysical parameters show proportionally large variations which appear to be responding to the solar cycles. For example, variation in low-altitude clouds is shown correlated with solar cycle, and the onset of Forbush decrease is shown correlated with the reduction of the vorticity area index. A possible sun-climate connection is that galactic cosmic rays modulated by solar activities influence cloud formation. In this paper, we apply wavelet transform to satellite and surface data to examine this hypothesis. Data analyzed include the time series for solar irradiance, sunspots, UV index, temperature, cloud coverage, and neutron counter measurements. The interactions among the elements in the Earth system under the external and internal forcings give out very complex signals. The periodicity of the forcings or signals could range widely. Since wavelet transforms can analyze multi-scale phenomena that are both localized in frequency and time, it is very useful techniques for detecting, understanding and monitoring climate changes. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kiang, RK (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 16 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4086-8 J9 P SOC PHOTO-OPT INS PY 2001 VL 4391 BP 303 EP 313 DI 10.1117/12.421210 PG 11 WC Engineering, Electrical & Electronic; Optics; Imaging Science & Photographic Technology SC Engineering; Optics; Imaging Science & Photographic Technology GA BS47F UT WOS:000169942000032 ER PT S AU Wang, Y AF Wang, Y BE Chen, RT Lipscomb, GF TI Digital tunable color filter and beam scanner SO WDM AND PHOTONIC SWITCHING DEVICES FOR NETWORK APPLICATIONS II SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on WDM and Photonic Switching Devices for Network Applications II CY JAN 25-26, 2001 CL SAN JOSE, CA SP SPIE DE electro-optics; filter; scanner; DWDM; digital; switching ID LIQUID-CRYSTAL AB A new technology invented at JPL of color filtering and beam scanning device based on electro-optical switching of internal-reflection states have been proposed for use in DWDM, display and measurement applications. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wang, Y (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-3967-3 J9 P SOC PHOTO-OPT INS PY 2001 VL 4289 BP 126 EP 129 DI 10.1117/12.424829 PG 4 WC Engineering, Electrical & Electronic; Optics; Telecommunications SC Engineering; Optics; Telecommunications GA BS47D UT WOS:000169941800020 ER PT S AU Salem, J Powers, L Allen, R Calomino, A AF Salem, J Powers, L Allen, R Calomino, A BE Tustison, RW TI Slow crack growth and fracture toughness of sapphire for a window application SO WINDOW AND DOME TECHNOLOGIES AND MATERIALS VII SE PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) LA English DT Proceedings Paper CT Conference on Window and Dome Technologies and Materials VII CY APR 16-17, 2001 CL ORLANDO, FL SP SPIE DE sapphire; fatigue; slow crack growth; reliability; strength; fracture toughness; life prediction; window AB The slow crack growth parameters, fracture toughness, and inert strength of the r- and a-planes of sapphire were measured in water in order to perform a life prediction on a pressurized sapphire window. The window is being considered for use in a combustion chamber on the International Space Station. Sapphire is relatively susceptible to stress corrosion in water despite a large strength in the absence of humidity. Two life prediction approaches were considered: a deterministic fracture mechanics approach and a Weibull based reliability approach. Preliminary results indicate that the window is feasible if a "short" finish is avoided. Fractography and additional predictions are being performed. C1 NASA, Glenn Res Ctr, Life Predict Branch, Cleveland, OH 44135 USA. RP Salem, J (reprint author), NASA, Glenn Res Ctr, Life Predict Branch, MS 49-7,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 18 TC 4 Z9 4 U1 1 U2 5 PU SPIE-INT SOC OPTICAL ENGINEERING PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98227-0010 USA SN 0277-786X BN 0-8194-4070-1 J9 P SOC PHOTO-OPT INS PY 2001 VL 4375 BP 41 EP 52 DI 10.1117/12.439192 PG 12 WC Computer Science, Software Engineering; Optics SC Computer Science; Optics GA BT73Q UT WOS:000173899200005 ER PT B AU Gutierrez, ME Rishe, ND Graham, S Rocha, GG Ye, XG Wolfson, O AF Gutierrez, ME Rishe, ND Graham, S Rocha, GG Ye, XG Wolfson, O BE Callaos, N DaSilva, IN Molero, J TI A web-enabled system for storage and retrieval of GOES-8 meteorological data from a semantic database SO WORLD MULTICONFERENCE ON SYSTEMICS, CYBERNETICS AND INFORMATICS, VOL 1, PROCEEDINGS: INFORMATION SYSTEMS DEVELOPMENT LA English DT Proceedings Paper CT 5th World Multi-Conference on Systemics, Cybernetics and Informatics (SCI2001)/7th International Conference on Information Systems Analysis and Synthesis (ISAS 2001) CY JUL 22-25, 2001 CL ORLANDO, FL SP Int Inst Informat & System, IEEE Comp Soc, Venezuela Chapter, World Org System & Cybernet, Ctr Syst Studies, Syst Soc Poland, Soc Appl Syst Res, Slovenian Artificial Intelligence Soc, Simon Bolivar Univ, Polish Syst Soc, Italian Soc System, Int Soc Syst Sci, Int Syst Inst, IEEE Latin Amer, Int Federat Syst Res, Cybernet & Human Knowing, Tunisian Sci Soc DE semantic database; GOES-8; Internet application; meteorological data; image data AB Meteorological data is a major component in the study and understanding of environment behaviors and their impact on society. Examples of the effects of hazardous weather conditions range from mild structural damage and agricultural and commercial losses to massive death and destruction. Meteorological data enables the prediction and analysis of weather phenomena and its possible life-threatening and property-damaging effects. The Geostationary Operational Environmental Satellite (GOES) system provides timely global weather information, including advanced warning of developing storms. Using GOES imagery, meteorologists are able to better study and understand atmospheric circulation patterns and behaviors. Capable of generating over 18 GB of meteorological data per day over the eastern United States, the GOES-8 is the first of this new generation of Earth-observing satellites. The High Performance Database Research Center (HPDRC), in conjunction with the NASA Regional Applications Center (RAC), has developed a web-enabled system which houses several gigabytes of GOES-8 meteorological data during each hurricane season. This system uses semantic database (Sem-ODB) technology to efficiently store and retrieve GOES-8 atmospheric data. Combining newly developed technologies and algorithms with the broadcast capabilities of the World Wide Web, HPDRC and NASA RAC make this vast source of information available to the general public and fellow scientists around the world. C1 Florida Int Univ, NASA, Reg Applicat Ctr, High Performance Database Res Ctr, Miami, FL 33149 USA. RP Gutierrez, ME (reprint author), Florida Int Univ, NASA, Reg Applicat Ctr, High Performance Database Res Ctr, Miami, FL 33149 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU INT INST INFORMATICS & SYSTEMICS PI ORLANDO PA 14269 LORD BARCLAY DR, ORLANDO, FL 32837 USA BN 980-07-7541-2 PY 2001 BP 62 EP 65 PG 4 WC Computer Science, Artificial Intelligence; Computer Science, Information Systems; Computer Science, Software Engineering SC Computer Science GA BU36Z UT WOS:000175785900012 ER PT B AU Rishe, ND Dyganova, O Selivonenko, A Chekmasov, M Mendoza, A AF Rishe, ND Dyganova, O Selivonenko, A Chekmasov, M Mendoza, A BE Callaos, N DaSilva, IN Molero, J TI MedFerret: Client-based semantic query integrator SO WORLD MULTICONFERENCE ON SYSTEMICS, CYBERNETICS AND INFORMATICS, VOL 1, PROCEEDINGS: INFORMATION SYSTEMS DEVELOPMENT LA English DT Proceedings Paper CT 5th World Multi-Conference on Systemics, Cybernetics and Informatics (SCI2001)/7th International Conference on Information Systems Analysis and Synthesis (ISAS 2001) CY JUL 22-25, 2001 CL ORLANDO, FL SP Int Inst Informat & System, IEEE Comp Soc, Venezuela Chapter, World Org System & Cybernet, Ctr Syst Studies, Syst Soc Poland, Soc Appl Syst Res, Slovenian Artificial Intelligence Soc, Simon Bolivar Univ, Polish Syst Soc, Italian Soc System, Int Soc Syst Sci, Int Syst Inst, IEEE Latin Amer, Int Federat Syst Res, Cybernet & Human Knowing, Tunisian Sci Soc DE heterogeneous databases; semantic schema; dynamic data retrieval; medical databases; Internet searching AB MedFerret is a semantic query merging application focused on dynamic data retrieval and on merging data available from medical sites on the Internet. MedFerret's system architecture is based on a heterogeneous database approach that utilizes the Semantic Object-oriented Data Model. The system is implemented as a Java applet on the client's computer and is, in fact, a multi-threaded Java web server that runs search queries against medical sites on the Internet and that returns results to several users simultaneously. C1 Florida Int Univ, NASA, Reg Applicat Ctr, High Performance Database Res Ctr, Miami, FL 33199 USA. RP Rishe, ND (reprint author), Florida Int Univ, NASA, Reg Applicat Ctr, High Performance Database Res Ctr, Miami, FL 33199 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU INT INST INFORMATICS & SYSTEMICS PI ORLANDO PA 14269 LORD BARCLAY DR, ORLANDO, FL 32837 USA BN 980-07-7541-2 PY 2001 BP 66 EP 70 PG 5 WC Computer Science, Artificial Intelligence; Computer Science, Information Systems; Computer Science, Software Engineering SC Computer Science GA BU36Z UT WOS:000175785900013 ER PT B AU Huang, NE AF Huang, NE BE Callaos, N Long, S Loutfi, M TI HHT: A review of the methods and many applications for nonsteady and nonlinear data analysis SO WORLD MULTICONFERENCE ON SYSTEMICS, CYBERNETICS AND INFORMATICS, VOL XVII, PROCEEDINGS: CYBERNETICS AND INFORMATICS: CONCEPTS AND APPLICATIONS (PT II) LA English DT Proceedings Paper CT 5th World Multi-Conference on Systemics, Cybernetics and Informatics (SCI2001)/7th International Conference on Information Systems Analysis and Synthesis (ISAS 2001) CY JUL 22-25, 2001 CL ORLANDO, FL SP Int Inst Informat & System, IEEE Comp Soc, Venezuela Chapter, World Org System & Cybernet, Ctr Syst Studies, Syst Soc Poland, Soc Appl Syst Res, Slovenian Artificial Intelligence Soc, Simon Bolivar Univ, Polish Syst Soc, Italian Soc System, Int Soc Syst Sci, Int Syst Inst, IEEE Latin Amer, Int Federat Syst Res, Cybernet & Human Knowing, Tunisian Sci Soc DE time-frequency analysis; nonstationary and nonlinear; time series analysis; Hilbert Spectrum; wavelet analysis; instantaneous frequency; empirical mode decomposition method; Hilbert-huang transform (HHT) ID HILBERT SPECTRUM; TIME-SERIES; DECOMPOSITION AB A new method for analyzing nonlinear and nonstationary data has been developed. The key part of the method is the Empirical Mode Decomposition (EMD) method with which any complicated data set can be decomposed into a finite and often small number of Intrinsic Mode Functions (IMF). An IMF is defined as any function having the same numbers of zero crossings and extrema, and also having symmetric envelopes defined by the local maxima and minima respectively. The IMF also admits well-behaved Hilbert transforms. This decomposition method is adaptive, and, therefore, highly efficient. Since the decomposition is based on the local characteristic time scale of the data, it is applicable to nonlinear and nonstationary processes. With the Hilbert transform, the Intrinsic Mode Functions yield instantaneous frequencies as functions of time that give sharp identifications of imbedded structures. The final presentation of the results is an energy-frequency-time distribution, designated as the Hilbert Spectrum. Comparisons with Wavelet and window Fourier analysis methods show the new approach presented here offers much better temporal and frequency resolutions. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Huang, NE (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Code 661, Greenbelt, MD 20771 USA. NR 27 TC 0 Z9 0 U1 0 U2 4 PU INT INST INFORMATICS & SYSTEMICS PI ORLANDO PA 14269 LORD BARCLAY DR, ORLANDO, FL 32837 USA BN 980-07-7557-9 PY 2001 BP 59 EP 66 PG 4 WC Computer Science, Artificial Intelligence; Computer Science, Cybernetics; Computer Science, Information Systems; Computer Science, Interdisciplinary Applications SC Computer Science GA BU41L UT WOS:000175939300011 ER PT B AU Long, SR AF Long, SR BE Callaos, N Long, S Loutfi, M TI Use of the empirical mode decomposition and hilbert-Huang transform in image analysis SO WORLD MULTICONFERENCE ON SYSTEMICS, CYBERNETICS AND INFORMATICS, VOL XVII, PROCEEDINGS: CYBERNETICS AND INFORMATICS: CONCEPTS AND APPLICATIONS (PT II) LA English DT Proceedings Paper CT 5th World Multi-Conference on Systemics, Cybernetics and Informatics (SCI2001)/7th International Conference on Information Systems Analysis and Synthesis (ISAS 2001) CY JUL 22-25, 2001 CL ORLANDO, FL SP Int Inst Informat & System, IEEE Comp Soc, Venezuela Chapter, World Org System & Cybernet, Ctr Syst Studies, Syst Soc Poland, Soc Appl Syst Res, Slovenian Artificial Intelligence Soc, Simon Bolivar Univ, Polish Syst Soc, Italian Soc System, Int Soc Syst Sci, Int Syst Inst, IEEE Latin Amer, Int Federat Syst Res, Cybernet & Human Knowing, Tunisian Sci Soc DE time-frequency analysis; nonstationary; nonlinear; time series analysis; hilbert spectrum; wavelet analysis; instantaneous frequency; empirical mode decomposition method; Hilbert-Huang transform (HHT); image analysis ID SPECTRUM AB The new method for analyzing nonlinear and nonstationary data described by Huang et al. [1,2] has been expanded to include the analysis of image data. The key steps of this new robust approach have been followed in this extension of the method. The images analyzed here are first decomposed into horizontal strips corresponding to each pixel row. For an image of 512 x 512 pixels, this would mean that a set of 512 slices, each 512 pixels long, would be first obtained. Then the Empirical Mode Decomposition (EMD) method of Huang et al. [1,2] and Huang [3] is applied, resulting in a small number of Intrinsic Mode Functions (IMF) for each image slice. Because the decomposition is based on the local characteristic time scale or length scale of the data, it is applicable to images of nonlinear and nonstationary processes. By next applying the Hilbert transform to the decomposition components of each image slice, the methods yield instantaneous frequencies or wave numbers as functions of time or distance, that give sharp identifications of imbedded structures. Thus for each image slice, we obtain a decomposed component set, ranging from the smallest time or length scales to the largest. The sum of these components is the original starting data. These results can then be used in several important ways. First, the components resulting can be reassembled into component images, by combining the first component from each slice together into a first component image (containing the highest frequencies or shortest length scales), and then repeating this for each subsequent component from each image slice. This gives a set of images that reveal different scales, from shortest to longest. Another presentation is obtained from the Hilbert transforms of the components, which can then be combined into an energy-frequency (or wave number)time distribution. Examples of this extension into images is given for water wave slopes in the presence of opposing current, and in satellite imagery of El Nino effects. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Observ Sci Branch,Wallops Flight Facil, Wallops Isl, VA 23337 USA. RP Long, SR (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Observ Sci Branch,Wallops Flight Facil, Wallops Isl, VA 23337 USA. RI Long, Steven/D-7248-2012 NR 10 TC 0 Z9 1 U1 0 U2 4 PU INT INST INFORMATICS & SYSTEMICS PI ORLANDO PA 14269 LORD BARCLAY DR, ORLANDO, FL 32837 USA BN 980-07-7557-9 PY 2001 BP 67 EP 71 PG 3 WC Computer Science, Artificial Intelligence; Computer Science, Cybernetics; Computer Science, Information Systems; Computer Science, Interdisciplinary Applications SC Computer Science GA BU41L UT WOS:000175939300012 ER PT B AU Pinzon, JE Pierce, JF Tucker, CJ AF Pinzon, JE Pierce, JF Tucker, CJ BE Callaos, N Long, S Loutfi, M TI Analysis of remote sensing data using Hilbert-Huang Transform SO WORLD MULTICONFERENCE ON SYSTEMICS, CYBERNETICS AND INFORMATICS, VOL XVII, PROCEEDINGS: CYBERNETICS AND INFORMATICS: CONCEPTS AND APPLICATIONS (PT II) LA English DT Proceedings Paper CT 5th World Multi-Conference on Systemics, Cybernetics and Informatics (SCI2001)/7th International Conference on Information Systems Analysis and Synthesis (ISAS 2001) CY JUL 22-25, 2001 CL ORLANDO, FL SP Int Inst Informat & System, IEEE Comp Soc, Venezuela Chapter, World Org System & Cybernet, Ctr Syst Studies, Syst Soc Poland, Soc Appl Syst Res, Slovenian Artificial Intelligence Soc, Simon Bolivar Univ, Polish Syst Soc, Italian Soc System, Int Soc Syst Sci, Int Syst Inst, IEEE Latin Amer, Int Federat Syst Res, Cybernet & Human Knowing, Tunisian Sci Soc DE normalized difference vegetation index; seasonal patterns; interannual variation in climate; empirical mode decomposition; noise removal ID SEA-SURFACE TEMPERATURE; AVHRR DATA; VEGETATION; SPECTRUM; LAND AB The information content derived from the empirical mode decomposition (EMD) is used to study seasonal and interannual variation in satellite-sensed vegetation index data. In a first application, daily normalized difference vegetation index (NDVI) images from the advanced very high resolution radiometers (AVHRR) onboard the National Oceanic and Atmospheric Administration (NOAA) polar satellites were corrected using EMD noise removal techniques. In this case, oscillations proper to intermittent events related to noisy-cloud contamination, to view geometry, and ground " true" signals are discriminated. Three intrinsic mode functions (IMF)s are used to associate confidence intervals to the corrected image at the pixel level providing a better quality product. As a second application, EMD is used to investigate linkages between dominant spatio-temporal dynamics of vegetation signals and modes of inter-annual variation in climate such as El Ni (n) over tildeo Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO). A direct linear relationship between ENSO and NAO IMF cycles with correspondent IMFs of vegetation provides a teleconnection index of the relative importance of the climate oscillations in the interannual variation of global land surface vegetation. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Pinzon, JE (reprint author), NASA, Goddard Space Flight Ctr, Code 923,SSAI, Greenbelt, MD 20771 USA. NR 19 TC 0 Z9 0 U1 1 U2 4 PU INT INST INFORMATICS & SYSTEMICS PI ORLANDO PA 14269 LORD BARCLAY DR, ORLANDO, FL 32837 USA BN 980-07-7557-9 PY 2001 BP 78 EP 83 PG 4 WC Computer Science, Artificial Intelligence; Computer Science, Cybernetics; Computer Science, Information Systems; Computer Science, Interdisciplinary Applications SC Computer Science GA BU41L UT WOS:000175939300014 ER PT S AU Nandra, K AF Nandra, K BE Czerny, B TI X-ray variability of AGN and correlations with spectral properties SO X-RAY AND GAMMA-RAY SIGNATURES OF BLACK HOLES AND WEAKLY MAGNETIZED NEUTRON STARS SE ADVANCES IN SPACE RESEARCH LA English DT Article; Proceedings Paper CT E1 2/H0 3 Symposium of COSPAR Scientific Commission E held at the 33rd COSPAR Scientific Assembly CY JUL, 2000 CL WARSAW, POLAND SP Danish ID ACTIVE GALACTIC NUCLEI; SEYFERT-GALAXY; BLACK-HOLE; MAGNETIC FLARES; ACCRETION DISK; CYGNUS X-1; COMPTONIZATION; PERIODICITY; RADIATION; NGC-6814 AB Rapid flux changes in the X-ray emission from active galactic nuclei axe commonly observed. The power-density spectra show a pseudo power-law form with a turnover at low frequencies and a high frequency break, similar to galactic black-hole candidates. There have been a few claims for periodicities but these axe not a well-established property of the class. The amplitude of variability depends on a number of source parameters, including luminosity and spectral properties. The variability amplitude is correlated with X-ray spectral index, and anti-correlated with the width of the permitted optical lines. In one particularly well-observed case, NGC 7469, we see a relationship between the X-ray and UV variability, which indicates that the dominant emission process for the X-rays is thermal Comptonization. Variations in the X-ray emission are related to changes in the UV seed photons, but it appears there must also be a mechanism - perhaps that which heats the Comptonizing corona - that induces rapid variability intrinsic to the X-rays. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Nandra, K (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 662, Greenbelt, MD 20771 USA. NR 56 TC 7 Z9 7 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA SARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0273-1177 J9 ADV SPACE RES PY 2001 VL 28 IS 2-3 BP 295 EP 306 DI 10.1016/S0273-1177(01)00409-4 PG 12 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BT45X UT WOS:000173048700004 ER PT S AU Nayakshin, S AF Nayakshin, S BE Czerny, B TI On Fe k alpha line emission by photo-ionized accretion disks SO X-RAY AND GAMMA-RAY SIGNATURES OF BLACK HOLES AND WEAKLY MAGNETIZED NEUTRON STARS SE ADVANCES IN SPACE RESEARCH LA English DT Article; Proceedings Paper CT E1 2/H0 3 Symposium of COSPAR Scientific Commission E held at the 33rd COSPAR Scientific Assembly CY JUL, 2000 CL WARSAW, POLAND SP Danish ID ACTIVE GALACTIC NUCLEI; X-RAY REFLECTION; THERMAL-INSTABILITY; PHOTOIONIZATION; OUTBURSTS; CORONAE AB We discuss (1) the importance of ionization physics in the interpretation of X-ray reflection features seen in spectra of most AGN and GBHCs. We show that changes in the ionization structure of the reflector with changes in the X-ray flux or its spectral shape may be confused with changes in the geometry of the accretion flow when studied with simpler (incomplete) X-ray reflection models. (2) In addition, we point out that iron lines from time-dependent accretion disks in their "quiescent" states should be narrow even if the cold accretion disk extends to the last stable orbit. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. RP Nayakshin, S (reprint author), NASA, Goddard Space Flight Ctr, LHEA, Code 661, Greenbelt, MD 20771 USA. NR 26 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA SARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0273-1177 J9 ADV SPACE RES PY 2001 VL 28 IS 2-3 BP 425 EP 431 DI 10.1016/S0273-1177(01)00411-2 PG 7 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BT45X UT WOS:000173048700020 ER PT S AU Proga, D Stone, JM Kallman, TR AF Proga, D Stone, JM Kallman, TR BE Czerny, B TI Line-driven disk winds in active galactic nuclei SO X-RAY AND GAMMA-RAY SIGNATURES OF BLACK HOLES AND WEAKLY MAGNETIZED NEUTRON STARS SE ADVANCES IN SPACE RESEARCH LA English DT Article; Proceedings Paper CT E1 2/H0 3 Symposium of COSPAR Scientific Commission E held at the 33rd COSPAR Scientific Assembly CY JUL, 2000 CL WARSAW, POLAND SP Danish ID BROAD ABSORPTION-LINE; QUASI-STELLAR OBJECTS; ACCELERATION; ALPHA AB We present the results of axisymmetric time-dependent hydrodynamic calculations of line-driven winds from accretion disks in active galactic nuclei (AGN). We assume the disk is flat, Keplerian, geometrically thin, and optically thick, radiating according to the alpha -disk prescription. The central engine of the AGN is a source of both ionizing X-rays and wind-driving ultraviolet (UV) photons. To calculate the radiation force, we take into account radiation from the disk and the central engine. The gas temperature and ionization state in the wind are calculated self-consistently from the photoionization and heating rate of the central engine. We find that a disk accreting onto a 10(8) M-circle dot yr(-1) black hole at the rate of 1.8 M-circle dot yr(-1) can launch a wind at similar to 10(16) cm from the central engine. The X-rays from the central object are significantly attenuated by the disk atmosphere so they cannot prevent the local disk radiation from pushing matter away from the disk. However in the supersonic portion of the flow high above the disk, the X-rays can overionize, the gas and decrease the wind terminal velocity. For a reasonable X-ray opacity, e.g., k(x) = 40 g(-1) cm(2), the disk wind can be accelerated by the central UV radiation to velocities of up to 15000 km s(-1) at a distance of similar to 10(17) cm from the central engine. The covering factor of the disk wind is similar to 0.2. The wind is unsteady and consists of an opaque, slow vertical flow near the disk that is bounded on the polar side by a high-velocity, stream. A typical column density through the fast stream is a few 10(23) cm(-2) so the stream is optically thin to the UV radiation. This low column density is precisely why gas can be accelerated to high velocities. I The fast stream contributes nearly 100% to the total wind mass loss rate of 0.5 M-circle dot yr(-1). Published by Elsevier Science Ltd on behalf of COSPAR. C1 NASA, Goddard Space Flight Ctr, LHEA, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Proga, D (reprint author), NASA, Goddard Space Flight Ctr, LHEA, Code 662, Greenbelt, MD 20771 USA. NR 16 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA SARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0273-1177 J9 ADV SPACE RES PY 2001 VL 28 IS 2-3 BP 459 EP 461 DI 10.1016/S0273-1177(01)00441-0 PG 3 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BT45X UT WOS:000173048700025 ER PT S AU Strohmayer, TE AF Strohmayer, TE BE Czerny, B TI Oscillations during thermonuclear X-ray bursts SO X-RAY AND GAMMA-RAY SIGNATURES OF BLACK HOLES AND WEAKLY MAGNETIZED NEUTRON STARS SE ADVANCES IN SPACE RESEARCH-SERIES LA English DT Article; Proceedings Paper CT E1 2/H0 3 Symposium of COSPAR Scientific Commission E held at the 33rd COSPAR Scientific Assembly CY JUL, 2000 CL WARSAW, POLAND SP Danish Space Res Inst, Comm Space Res ID QUASI-PERIODIC OSCILLATIONS; ACCRETING NEUTRON-STAR; BRIGHTNESS OSCILLATIONS; MILLISECOND PULSATIONS; COHERENT OSCILLATIONS; TIMING-EXPLORER; KS 1731-260; 4U 1636-536; BINARY; PROPAGATION AB High amplitude, nearly coherent X-ray brightness oscillations during thermonuclear X-ray bursts were discovered with the Rossi X-ray Timing Explorer (RXTE) in early 1996. Spectral and timing evidence strongly supports the conclusion that these oscillations are caused by rotational modulation of the burst emission and that they reveal the spin frequency of neutron stars in low mass X-ray binaries, a long sought goal of X-ray astronomy. Studies carried out over the past year have led to the discovery of burst oscillations in four new sources, bringing to ten the number with confirmed burst oscillations. I review the status of our knowledge of these oscillations and indicate how they can be used to probe the physics of neutron stars. For a few burst oscillation sources it has been proposed that the strongest and most ubiquitous frequency is actually the first overtone of the spin frequency and hence that two nearly antipodal hot spots axe present on the neutron star. This inference has important implications for both the physics of thermonuclear burning as well as the mass - radius relation for neutron stars, so its confirmation is crucial. I discuss recent attempts to confirm this hypothesis for 4U 1636-53, the source for which a signal at the putative fundamental (290 Hz) has been claimed. Published by Elsevier Science Ltd on behalf of COSPAR. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Strohmayer, TE (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 42 TC 29 Z9 29 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA SARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0273-1177 J9 ADV SPACE RES-SERIES PY 2001 VL 28 IS 2-3 BP 511 EP 522 DI 10.1016/S0273-1177(01)00422-7 PG 12 WC Engineering, Aerospace; Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Engineering; Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA BT45X UT WOS:000173048700032 ER PT S AU Harding, AK AF Harding, AK BE White, NE Malaguti, G Palumbo, GGC TI High-energy emission from isolated pulsars SO X-RAY ASTRONOMY: STELLAR ENDPOINTS, AGN, AND THE DIFFUSE X-RAY BACKGROUND SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT Conference on X-Ray Astronomy CY SEP 06-10, 1999 CL BOLOGNA, ITALY SP ITESRE CNR, NASA GSFC, ASI DE pulsars : general; acceleration of particles; magnetic fields ID GAMMA-RAY PULSARS; X-RAY; POLAR CAPS; NEUTRON-STARS; OUTER GAPS; RADIATION; REPEATERS; CASCADES; ZONES AB Rotation-powered pulsars can produce observable high-energy emission by a number of mechanisms. Non-thermal X-rays and gamma-rays are produced by relativistic particles, accelerated in the pulsar magnetosphere at a still unknown location, via curvature, synchrotron and inverse Compton radiation. Thermal X-rays may be produced at the stellar surface by cooling of the neutron star or by a variety of possible heating mechanisms that include the bombardment of the surface by backflowing particles and internal friction. In pulsars with ultra-strong fields, known as magnetars, the magnetic field is the dominant energy source responsible for both the radiation and the spin-down behavior. I will review models for pulsar emission in light of recent X-ray data from ROSAT, ASCA and RXTE. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Harding, AK (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012; Harding, Alice/D-3160-2012 OI White, Nicholas/0000-0003-3853-3462; NR 33 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0043-1 J9 AIP CONF PROC PY 2001 VL 599 BP 150 EP 159 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU03M UT WOS:000174772600015 ER PT S AU Nandra, K AF Nandra, K BE White, NE Malaguti, G Palumbo, GGC TI Iron K line emission in AGN: Observations SO X-RAY ASTRONOMY: STELLAR ENDPOINTS, AGN, AND THE DIFFUSE X-RAY BACKGROUND SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT Conference on X-Ray Astronomy CY SEP 06-10, 1999 CL BOLOGNA, ITALY SP ITESRE CNR, NASA GSFC, ASI DE accretion; accretion disks; line : proflies; galaxies : active; galaxies : Seyfert ID ACTIVE GALACTIC NUCLEI; X-RAY REFLECTION; BLACK-HOLE; SEYFERT-1 GALAXIES; ASCA OBSERVATIONS; ALPHA LINES; COLD MATTER; VARIABILITY; MCG-6-30-15; PROFILES AB Iron Kalpha lines are key diagnostics of the central regions of AGN. Their profiles indicate that they are formed deep in the potential well of the central black hole, where extreme broadening and red shift occur. The profiles are most easily reproducible in an accretion disk: the lack of significant emission blue-ward of the rest energy is difficult produce in other geometries. In one source an apparent (and perhaps variable) absorption feature in the red wing of the line may represent rare evidence for inflow onto the black hole. Sample analysis has defined the mean properties, showing a strong concentration of the emission in the central regions and face-on accretion disks, at least in Seyfert 1 galaxies. Surprising results have been obtained from examination of the line variability. Strong profile changes may be accounted for by changes in the illumination pattern of the central, relativistic part of the disk. In at least the case of MCG6-30-15, there is evidence for emission from within 6R(g), possibly indicating a spinning black hole. Developing an understanding of these complex changes has the potential to reveal the geometry and kinematics of the inner few gravitational radii around extragalactic black holes. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Nandra, K (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 49 TC 2 Z9 2 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0043-1 J9 AIP CONF PROC PY 2001 VL 599 BP 264 EP 273 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU03M UT WOS:000174772600027 ER PT S AU Strohmayer, TE AF Strohmayer, TE BE White, NE Malaguti, G Palumbo, GGC TI Oscillations during thermonuclear X-ray bursts: A new probe of neutron stars SO X-RAY ASTRONOMY: STELLAR ENDPOINTS, AGN, AND THE DIFFUSE X-RAY BACKGROUND SE AIP Conference Proceedings LA English DT Proceedings Paper CT Conference on X-Ray Astronomy CY SEP 06-10, 1999 CL BOLOGNA, ITALY SP ITESRE CNR, NASA GSFC, ASI DE stars : neutron; stars : rotation; X-rays : bursts; equation of state ID BRIGHTNESS OSCILLATIONS; MILLISECOND PULSATIONS; RISING PHASE; BINARIES; PULSARS; MODEL; PROPAGATION; SEARCHES; FLASHES AB Observations of thermonuclear (also called Type I) X-ray bursts from neutron stars in low mass X-ray binaries (LMXB) with the Rossi X-ray Timing Explorer (RXTE) have revealed large amplitude, high coherence X-ray brightness oscillations with frequencies in the 300 - 600 Hz range. Substantial spectral and timing evidence point to rotational modulation of the X-ray burst flux as the cause of these oscillations, and it is likely that they reveal the spin frequencies of neutron stars in LMXB from which they are detected. Here I review the status of our knowledge of these oscillations and describe how they can be used to constrain the masses and radii of neutron stars as well as the physics of thermonuclear burning on accreting neutron stars. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Strohmayer, TE (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM stroh@clarence.gsfc.nasa.gov RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 31 TC 3 Z9 3 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0043-1 J9 AIP CONF PROC PY 2001 VL 599 BP 377 EP 386 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU03M UT WOS:000174772600037 ER PT S AU Kotani, T Kawai, N Nagase, F Namiki, M Sakano, M Takeshima, T Ueda, Y Matsuoka, M AF Kotani, T Kawai, N Nagase, F Namiki, M Sakano, M Takeshima, T Ueda, Y Matsuoka, M BE White, NE Malaguti, G Palumbo, GGC TI ASCA observations of the new jet system XTE J1748-288 SO X-RAY ASTRONOMY: STELLAR ENDPOINTS, AGN, AND THE DIFFUSE X-RAY BACKGROUND SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT Conference on X-Ray Astronomy CY SEP 06-10, 1999 CL BOLOGNA, ITALY SP ITESRE CNR, NASA GSFC, ASI DE binaries : close; stars : individual (XTE J1748-288); X-rays : stars AB XTE J1748-288 is the newly discovered transient with a one-sided radio jet. It was observed with ASCA on 1998/09/06 and 1998/09/26, 100 days after the onset of the radio-X-ray outburst. The spectra were expressed with an attenuated power-law model, and the 2-6-keV flux was 4.6(-0.8)(+1.0) x 10(-11) erg s(-1) cm(-2) and 2.2(-0.6)(+0.8) x 10(-12) for 09/06 and 09/26, respectively. The light curve shows that the steady exponential decay with an e-folding time of 14 days lasted over 100 days and 4 orders of magnitude from the peak of the outburst. Possible detection of iron line is reported. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Kotani, T (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 12 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0043-1 J9 AIP CONF PROC PY 2001 VL 599 BP 462 EP 465 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU03M UT WOS:000174772600049 ER PT S AU Weaver, KA AF Weaver, KA BE White, NE Malaguti, G Palumbo, GGC TI Probing dense matter in the cores of AGN: Observations with RXTE and ASCA SO X-RAY ASTRONOMY: STELLAR ENDPOINTS, AGN, AND THE DIFFUSE X-RAY BACKGROUND SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT Conference on X-Ray Astronomy CY SEP 06-10, 1999 CL BOLOGNA, ITALY SP ITESRE CNR, NASA GSFC, ASI DE galaxies : active; galaxies : individual (MCG-2-58-22) galaxies : individual (MCG-5-23-15); galaxies : nuclei; galaxies : Seyfert; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; SEYFERT-GALAXIES; COLD MATTER; RAY AB Preliminary results from an X-ray spectral study of Seyfert 1 galaxies with ASCA and RXTE are presented. From an analysis of X-ray reprocessing features of Compton reflection and Fe Kalpha fluorescence, it is found that iron line strength is not necessarily a good predictor of the amount of reflection. The variability properties of Fe Kalpha and reflection do not necessarily scale together and substantial decoupling of the behavior of the reprocessed flux with respect to continuum variability is common. Such trends suggest the presence of multiple and/or complex regions of dense matter in AGN cores and that standard, simple accretion disk models drastically oversimplify reality. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Weaver, KA (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 8 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0043-1 J9 AIP CONF PROC PY 2001 VL 599 BP 482 EP 485 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU03M UT WOS:000174772600054 ER PT S AU MacDonald, DR Gruber, DE Boldt, EA AF MacDonald, DR Gruber, DE Boldt, EA BE White, NE Malaguti, G Palumbo, GGC TI Measurements of fluctuations in the hard X-ray background with RXTE SO X-RAY ASTRONOMY: STELLAR ENDPOINTS, AGN, AND THE DIFFUSE X-RAY BACKGROUND SE AIP Conference Proceedings LA English DT Proceedings Paper CT Conference on X-Ray Astronomy CY SEP 06-10, 1999 CL BOLOGNA, ITALY SP ITESRE CNR, NASA GSFC, ASI DE background fields; X-rays; fluctuations; AGN AB During normal observations, the High Energy X-ray Timing Experiment instrument (HEXTE) on the Rossi X-ray Timing Explorer (RXTE) Spacecraft makes nearly simultaneous observations of two pairs of background fields separated by 3.0 degrees. Differences in fluxes from these pairs of background fields can be used to detect a source population much deeper than can be studied from individual detections. We have measured the fluctuations in the X-ray background (XRB) from 15-40 keV using differences between adjacent HEXTE background fields. The fluctuations as a fraction of the XRB flux are : 0.092 +/- 0.014 % from 15 to 20 keV, 0.11 +/- 0.02 % from 20 to 25 keV and 0.23 +/- 0.08 % from 34 to 41 keV for a 1.1 square degree field of view. The measured fractional fluctuations increase with energy, which implies that the effective number of contributing sources is decreasing with energy. The fluctuation level and energy dependence are consistent with HEAO-1 results. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP MacDonald, DR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM danmac@mamacass.ucsd.edu; dgruber@ucsd.edu NR 17 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0043-1 J9 AIP CONF PROC PY 2001 VL 599 BP 734 EP 737 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU03M UT WOS:000174772600116 ER PT S AU Terashima, Y Yaqoob, T Serlemitsos, PJ Kunieda, H Misaki, K Ptak, AF Ho, LC AF Terashima, Y Yaqoob, T Serlemitsos, PJ Kunieda, H Misaki, K Ptak, AF Ho, LC BE White, NE Malaguti, G Palumbo, GGC TI Variability of the iron line in the low-luminosity AGN NGC 4579 SO X-RAY ASTRONOMY: STELLAR ENDPOINTS, AGN, AND THE DIFFUSE X-RAY BACKGROUND SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT Conference on X-Ray Astronomy CY SEP 06-10, 1999 CL BOLOGNA, ITALY SP ITESRE CNR, NASA GSFC, ASI DE galaxies : nuclei; galaxies : individual (NGC 4579) ID ACTIVE GALACTIC NUCLEI; NGC-4579; M81 AB We present results of ASCA observations of the low-luminosity AGN (LLAGN) NGC 4579 in 1995 July and 1998 December which show evidence for spectral variability. The X-ray luminosity in the 1998 observations is 2 x10(41) ergs s(-1) in the 2-10 keV band and about 35% larger than in 1995. An Fe K emission line is clearly detected in both observations. The center energy is 6.73 (+0.13)(-0.12) keV in 1995 and 6.39 +/- 0.09 keV in 1998. if we model the Fe line with two Gaussians centered at 6.4 keV and 6.7 keV, the line intensity of the 6.7 keV line decreased while that of the 6.4 keV line increased within an interval of 3.5 years. This variability rules out thermal plasmas in the host galaxy as the origin of the ionized Fe line in this LLAGN. The detection of a variable 6.4 keV line suggests that an optically thick standard accretion disk is present in this object, whose Eddington ratio is only L-Bol/L-Edd similar to 2 x 10(-3). C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Terashima, Y (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 7 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0043-1 J9 AIP CONF PROC PY 2001 VL 599 BP 983 EP 986 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU03M UT WOS:000174772600177 ER PT S AU White, NE Tananbaum, H AF White, NE Tananbaum, H BE White, NE Malaguti, G Palumbo, GGC TI The Constellation X-ray mission SO X-RAY ASTRONOMY: STELLAR ENDPOINTS, AGN, AND THE DIFFUSE X-RAY BACKGROUND SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT Conference on X-Ray Astronomy CY SEP 06-10, 1999 CL BOLOGNA, ITALY SP ITESRE CNR, NASA GSFC, ASI DE instrumentation : detectors; techniques : spectroscopic; X-rays : general AB The Constellation-X mission is a large collecting area X-ray facility, emphasizing observations at high spectral resolution (E/DeltaE similar to 300-3000) while covering a broad energy band (0.25-40 keV). This mission will achieve a factor of 100 increased sensitivity over current capabilities and is optimized to observe the effects of extreme gravity close to black holes, and test models for the formation of large scale structure in the Universe. It is apart of NASA's strategic plan for launch towards the end of the first decade of the 21(st) century. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP White, NE (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 9 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0043-1 J9 AIP CONF PROC PY 2001 VL 599 BP 1027 EP 1030 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU03M UT WOS:000174772600188 ER PT B AU White, NE Bookbinder, JA Tananbaum, H AF White, NE Bookbinder, JA Tananbaum, H BE Giacconi, R Serio, S Stella, L TI The Constellation X-ray mission SO X-RAY ASTRONOMY 2000 SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT X-Ray Astronomy 2000 Conference CY SEP 04-09, 2000 CL MONDELLO, ITALY SP Soc Astron Italiana, Agenzia Spaziale Italiana, Citta Palermo, Compaq, CNR, Makers, Prov Reg Palermo, Reg Sicilia, Telecom Italia, Univ Studi Palermo ID TRANSITION-EDGE-MICROCALORIMETER; EV ENERGY RESOLUTION AB The Constellation-X mission is a large collecting area Xray observatory emphasizing high spectral resolution (R = E/DeltaE similar to 300-3000) and a broad energy band (0.25-60 keV). By increasing the telescope aperture and utilizing efficient spectrometers the mission will achieve a factor of 20-100 increased sensitivity over current high resolution X-ray spectroscopy missions. The use of focusing optics across the 10-60 keV band will provide a similar factor of 100 increased sensitivity in this band. Constellation-X will be a multiple purpose observatory that will enable routine observations of faint X-ray sources at high spectral resolution. The many science topics include observing the effects of strong gravity close to the event horizon of black holes in AGN, constraining the accretion geometry in AGN, observe the formation of the first clusters of galaxies, and constraining the Baryon content of the Universe. The Constellation-X mission recently received a strong endorsement from the National Academy of Sciences McKee-Taylor Astronomy and Astrophysics Survey of high priority projects for the first decade of the 21st century. Key technologies under development for the mission include lightweight high throughput X-ray optics, multilayer coatings to enhance the hard X-ray performance of X-ray optics, micro-calorimeter spectrometer arrays with 2 eV resolution, low power CCD arrays, lightweight gratings and hard X-ray imaging detectors. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP White, NE (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 12 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-071-4 J9 ASTR SOC P PY 2001 VL 234 BP 597 EP 610 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU25U UT WOS:000175482700075 ER PT B AU Zhang, W Petre, R White, NE AF Zhang, W Petre, R White, NE BE Giacconi, R Serio, S Stella, L TI Generation-X: A large aperture, high angular resolution X-ray observatory for the 2010's SO X-RAY ASTRONOMY 2000 SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT X-Ray Astronomy 2000 Conference CY SEP 04-09, 2000 CL MONDELLO, ITALY SP Soc Astron Italiana, Agenzia Spaziale Italiana, Citta Palermo, Compaq, CNR, Makers, Prov Reg Palermo, Reg Sicilia, Telecom Italia, Univ Studi Palermo ID TELESCOPE AB We describe a mission concept for an X-ray observatory with an effective area of 150 m(2) at 1 keV and an angular resolution of similar to 0.1 arc second. Such an observatory will be able to image 1000 times deeper than Chandra, observing sources with a flux of 2(-20) ergs/cm(2)/s. It will also be able to obtain high resolution spectra from sources 100-1000 times fainter than those observable by Constellation-X. The scientific goals of such a mission would be to probe the X-ray emission from the universe at z = 5 - 10. It would observe all of galaxies in the Universe, the formation of the first quasars and the creation of the first metals in starburst galaxies. The need for such a mission has been recognized in the recent U.S. National Academy of Sciences decadal survey report, as a long term goal for Xray astronomy and an important area for technology investment over the coming decades. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Zhang, W (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RI White, Nicholas/B-6428-2012 OI White, Nicholas/0000-0003-3853-3462 NR 9 TC 9 Z9 9 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-071-4 J9 ASTR SOC P PY 2001 VL 234 BP 657 EP 662 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU25U UT WOS:000175482700081 ER PT B AU Webb, RA AF Webb, RA BE Jayawardhana, R Greeme, TP TI Search for members of the TW Hydrae association SO YOUNG STARS NEAR EARTH: PROGRESS AND PROSPECTS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on Young Stars Near Earth CY MAR 28-30, 2001 CL NASA AMES RES CTR, MT VIEW, CA SP NASA Off Space Sci HO NASA AMES RES CTR ID LOW-MASS STARS; TAURI STARS; HD-98800 AB The known membership of the TW Hydrae Association has swelled to approximately 20 systems containing nearly 40 stars. However, with the exception of the dusty A-type star, HR 4790, and the recently identified HD 102458, all known members of the Association have spectral type K5 or later. The apparent lack of "solar-type stars" indicates an unusually steep mass function. However this is likely a result of a bias created by the chosen search strategy. Here we identify over two dozen stars in the vicinity of the TWA. Two of which are Li rich M-stars, identified as TWA members. Most of the remaining stars axe spectral type F, G or K, are bright X-ray sources, have strong Li absorption lines and many share similar proper motion to known TWA members, But without parallax measurements needed to place stars on an HR diagram, these characteristics are inadequate to unambiguously differentiate between TWA members and stars which are part of the older, diffuse "Local Association". It is Likely that, as more data are collected, some of these stars will prove to be the "missing" intermediate mass TWA members, while others will be found to be Local Association stars. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Webb, RA (reprint author), NASA, Ames Res Ctr, MS 245-6, Moffett Field, CA 94035 USA. NR 19 TC 4 Z9 4 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-082-X J9 ASTR SOC P PY 2001 VL 244 BP 10 EP 15 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34B UT WOS:000175724200002 ER PT B AU Hearty, TJ AF Hearty, TJ BE Jayawardhana, R Greeme, TP TI MBM 12: The nearest known star-forming cloud SO YOUNG STARS NEAR EARTH: PROGRESS AND PROSPECTS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on Young Stars Near Earth CY MAR 28-30, 2001 CL NASA AMES RES CTR, MT VIEW, CA SP NASA Off Space Sci HO NASA AMES RES CTR AB I describe the MBM12 cloud and investigate the X-ray Lu-minosity Function (XLF) in light of the recent evidence that the cloud may be more distant than previously thought. C1 Jet Prop Lab, Pasadena, CA 91109 USA. RP Hearty, TJ (reprint author), Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-082-X J9 ASTR SOC P PY 2001 VL 244 BP 22 EP 25 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34B UT WOS:000175724200004 ER PT B AU Sahu, MS AF Sahu, MS BE Jayawardhana, R Greeme, TP TI Gas and dust in the solar Neighborhood SO YOUNG STARS NEAR EARTH: PROGRESS AND PROSPECTS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on Young Stars Near Earth CY MAR 28-30, 2001 CL NASA AMES RES CTR, MT VIEW, CA SP NASA Off Space Sci HO NASA AMES RES CTR ID LOCAL INTERSTELLAR-MEDIUM; LATE-TYPE STARS; SIGHT; LINE; IDENTIFICATION; SUPERBUBBLE; ASSOCIATION; DEUTERIUM; CAPELLA; MATTER AB The significance of Local Interstellar Medium (LISM) and its constituents are briefly reviewed. Due to its proximity and its massive star content, the Sco-Cen association influences the kinematics of the nearby ISM. Recent reports on the kinematics of the eta Cha and TWHya aggregates suggest that they are associated with the Sco-Cen complex. It is likely there is a large, yet undiscovered population of such young stellar aggregates and some of these stars may in fact be very close to the Sun. Some of the diffuse LISM clouds and these young stellar groups are kinematically associated and are being affected by supernovae and shocks originating in the Sco-Cen associations. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Sahu, MS (reprint author), NASA, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. NR 35 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-082-X J9 ASTR SOC P PY 2001 VL 244 BP 91 EP 97 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34B UT WOS:000175724200017 ER PT B AU Kimble, RA Grady, CA Devine, D Bruce, E AF Kimble, RA Grady, CA Devine, D Bruce, E BE Jayawardhana, R Greeme, TP TI STIS observations of the disk and outflow of the Herbig Ae star HD163296 SO YOUNG STARS NEAR EARTH: PROGRESS AND PROSPECTS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on Young Stars Near Earth CY MAR 28-30, 2001 CL NASA AMES RES CTR, MT VIEW, CA SP NASA Off Space Sci HO NASA AMES RES CTR AB We have observed the nearby Herbig Ae star HD163296 with the HST/Space Telescope Imaging Spectrograph (STIS) in a program of high spatial resolution coronagraphic imaging in the visible as well as long-slit spectroscopy in the visible and ultraviolet. These observations have revealed the presence of a circumstellar disk with similar to450 AU radius, as well as a collimated outflow previously unexpected for a Herbig Ae star of several Myr age. The collimated outflow and various UV spectral signatures are suggestive of magnetospherically channelled accretion, in analogy to models of T Tauri stars. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kimble, RA (reprint author), NASA, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. NR 6 TC 1 Z9 1 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-082-X J9 ASTR SOC P PY 2001 VL 244 BP 215 EP 220 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34B UT WOS:000175724200036 ER PT B AU Marley, MS AF Marley, MS BE Jayawardhana, R Greeme, TP TI Models of young brown dwarfs and giant planets SO YOUNG STARS NEAR EARTH: PROGRESS AND PROSPECTS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on Young Stars Near Earth CY MAR 28-30, 2001 CL NASA AMES RES CTR, MT VIEW, CA SP NASA Off Space Sci HO NASA AMES RES CTR ID GLIESE 229B; CARBON-MONOXIDE; ATMOSPHERES; EVOLUTIONARY AB Young stars are a logical 'lamp post' around which to search for young, bright extrasolar planets. The coolest, least massive, and perhaps most interesting of such objects, however, may appear differently than predicted by models. A variety of processes, including cloud formation and transport of non-equilibrium species, can affect the emergent spectrum of an extrasolar giant planet or brown dwarf. Here I briefly review a few such processes that might alter the emergent flux predicted by existing models. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Marley, MS (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI Marley, Mark/I-4704-2013 NR 21 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-082-X J9 ASTR SOC P PY 2001 VL 244 BP 316 EP 321 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34B UT WOS:000175724200052 ER PT B AU Bryden, G AF Bryden, G BE Jayawardhana, R Greeme, TP TI Ejected planets near young stars SO YOUNG STARS NEAR EARTH: PROGRESS AND PROSPECTS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on Young Stars Near Earth CY MAR 28-30, 2001 CL NASA AMES RES CTR, MT VIEW, CA SP NASA Off Space Sci HO NASA AMES RES CTR ID PROTOSTELLAR DISKS; MASS OBJECTS; PROTOPLANETS; MIGRATION AB The ejection of planets from young protostellar disks is considered. As a result of neighboring protoplanets interaction with each other and with the surrounding disk, many young planets are ejected. Their ejection velocities are small enough (typically a few km/s) for many to stay close to their parent cluster. However, the ejected planets generally have masses less than those which have potentially been observed in Orion and in the TW Hydrae Association. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bryden, G (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr MS 169-506, Pasadena, CA 91109 USA. NR 15 TC 2 Z9 2 U1 0 U2 1 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-082-X J9 ASTR SOC P PY 2001 VL 244 BP 328 EP 333 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34B UT WOS:000175724200054 ER PT B AU Greene, TP AF Greene, TP BE Jayawardhana, R Greeme, TP TI FAME: The full-sky astrometric mapping explorer's potential for observing young nearby stars SO YOUNG STARS NEAR EARTH: PROGRESS AND PROSPECTS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on Young Stars Near Earth CY MAR 28-30, 2001 CL NASA AMES RES CTR, MT VIEW, CA SP NASA Off Space Sci HO NASA AMES RES CTR AB The Full-sky Astrometric Mapping Explorer will determine the positions, parallaxes, proper motions, and multi-color photometric magnitudes of 4 x 10(7) Stars with 5 less than or equal to mv less than or equal to 15. The parallaxes and positions of mv less than or equal to 9 stars will be measured to an accuracy of 50 pas, and mv = 15 ones will be measured to 500 pas. Thus the distances of all mv less than or equal to 15 stars within 100 pc of Earth will be determined to an accuracy of 5% or better. This will afford a revolution in the field: FAME will identify many more nearby young stars and associations, provide precise distances and luminosities which will reveal pre-main-sequence evolution, provide a detailed picture of local star formation history, and detect companions below 10 M-Jup. FAME is expected to launch in October 2004 and will have a 5 year total mission life. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Greene, TP (reprint author), NASA, Ames Res Ctr, MS 245-6, Moffett Field, CA 94035 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-082-X J9 ASTR SOC P PY 2001 VL 244 BP 348 EP 352 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34B UT WOS:000175724200057 ER PT B AU Beichman, C AF Beichman, C BE Jayawardhana, R Greeme, TP TI The search for young planetary systems SO YOUNG STARS NEAR EARTH: PROGRESS AND PROSPECTS SE ASTRONOMICAL SOCIETY OF THE PACIFIC CONFERENCE SERIES LA English DT Proceedings Paper CT Workshop on Young Stars Near Earth CY MAR 28-30, 2001 CL NASA AMES RES CTR, MT VIEW, CA SP NASA Off Space Sci HO NASA AMES RES CTR AB The Space Interferometer Mission (SIM) will provide a census of planetary systems by conducting a broad survey of 2,000 stars that will be sensitive to the presence of planets with masses as small as similar to15 Earth masses (1 Uranus mass) and a deep survey of similar to250 of the nearest stars with a mass limit of similar to3 Earth massas. The broad survey will include stars spanning a wide range of ages, spectral types, metallicity, and other important parameters. Within this larger context, the Young Stars and Planets Key Project will study similar to200 stars with ages from 1 Myr to 100 Myr to understand the formation and dynamical evolution of gas giant planets. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Beichman, C (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 7 TC 5 Z9 5 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 USA BN 1-58381-082-X J9 ASTR SOC P PY 2001 VL 244 BP 376 EP 382 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BU34B UT WOS:000175724200062 ER PT S AU Hwang, U AF Hwang, U BE Holt, SS Hwang, U TI X-ray observations of young supernova remnants SO YOUNG SUPERNOVA REMNANTS SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 11th Annual Astrophysics Conference CY OCT 16-18, 2000 CL COLLEGE PK, MD ID CASSIOPEIA-A; NOVA REMNANT; EXPANSION; EMISSION; EJECTA; SPECTROSCOPY; SHOCK; ASCA; VELOCITY; CHANDRA AB This brief review of recent X-ray observations of young supernova remnants highlights results obtained by the Chandra and XMM Newton Observatories since their launch last year. Their impressive capabilities are illustrated by results for spectral imaging, and For spatially resolved spectroscopy that isolates emission from individual ejecta knots and from the forward shock. I also review X-ray dynamical studies of supernova remnants, which should undergo significant advances during this new era. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Hwang, U (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 40 TC 2 Z9 2 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0001-6 J9 AIP CONF PROC PY 2001 VL 565 BP 143 EP 152 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS29B UT WOS:000169367800018 ER PT S AU Williams, R Petre, R Holt, SS AF Williams, R Petre, R Holt, SS BE Holt, SS Hwang, U TI A look at SNR 0519-69.0 with Chandra's ACIS SO YOUNG SUPERNOVA REMNANTS SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 11th Annual Astrophysics Conference CY OCT 16-18, 2000 CL COLLEGE PK, MD ID LARGE MAGELLANIC CLOUD; SUPERNOVA-REMNANTS AB The young, Balmer-dominated SNR 0519 69.0 in the Large Magellanic Cloud is of the class of objects typified by the Tycho supernova remnant. Recent observations with Chandra's Advanced CCD Imaging Spectrometer have shown the X-ray structure of this object in unprecedented detail. ACIS's combination of spatial and spectral resolution allow us to compare the X-ray spectra of the outermost limb emission to that from the rest of the remnant, revealing intriguing differences in spectral features. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Williams, R (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 4 TC 2 Z9 2 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0001-6 J9 AIP CONF PROC PY 2001 VL 565 BP 185 EP 188 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS29B UT WOS:000169367800024 ER PT S AU Gull, TR Sollerman, J Lundqvist, P Sonneborn, G Lindler, D AF Gull, TR Sollerman, J Lundqvist, P Sonneborn, G Lindler, D BE Holt, SS Hwang, U TI NUV and FUV spectroscopic timing observations of the Crab pulsar with HST/STIS SO YOUNG SUPERNOVA REMNANTS SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 11th Annual Astrophysics Conference CY OCT 16-18, 2000 CL COLLEGE PK, MD ID ULTRAVIOLET C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Gull, TR (reprint author), NASA, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 3 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0001-6 J9 AIP CONF PROC PY 2001 VL 565 BP 315 EP 316 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS29B UT WOS:000169367800043 ER PT S AU Harding, AK AF Harding, AK BE Holt, SS Hwang, U TI Pulsar emission and central sources in young supernova remnants SO YOUNG SUPERNOVA REMNANTS SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 11th Annual Astrophysics Conference CY OCT 16-18, 2000 CL COLLEGE PK, MD ID GAMMA-RAY PULSARS; MAGNETIZED NEUTRON-STARS; RAPIDLY SPINNING PULSARS; X-RAY; OUTER MAGNETOSPHERE; PAIR CREATION; POLAR CAPS; RADIATION; GAPS; MODEL AB Recent high-energy detections of radio-quiet neutron stars are changing our view of central sources in young supernova remnants. There are at least several classes of sources that make up this radio-quiet population: rotation-powered pulsars with magnetic fields around 10(12) G, non-rotation powered pulsars (possibly magnetars) and non-pulsating X-ray point sources. I will review pulsar emission mechanisms for both thermal and non-thermal emission in both rotation-powered and non-rotation powered sources. Radio quiescence in some cases may be caused by unfavorable alignment with the radio beams. In pulsars with magnetic fields exceeding 10(14) G, radio quiescence may be due to the suppression of pair production by photon splitting. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Harding, AK (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 49 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0001-6 J9 AIP CONF PROC PY 2001 VL 565 BP 351 EP 359 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS29B UT WOS:000169367800052 ER PT S AU Petre, R AF Petre, R BE Holt, SS Hwang, U TI Evidence for cosmic ray acceleration in supernova remnants from X-ray observations SO YOUNG SUPERNOVA REMNANTS SE AIP CONFERENCE PROCEEDINGS LA English DT Proceedings Paper CT 11th Annual Astrophysics Conference CY OCT 16-18, 2000 CL COLLEGE PK, MD ID SHOCK ACCELERATION; EMISSION; ELECTRONS; SN-1006; SHELL; MODELS AB Spatially-resolved X-ray spectroscopic observations over the past several years have led to the discovery of non-thermal X-ray emission arising in the shells of many young Galactic supernova remnants, most notably SN 1006 and Cas A. This emission is thought to be synchrotron emission from electrons shock acclerated to hundreds of TeV, and thus represents strong evidence that cosmic rays art! accelerated in SNR shocks. The inferences made using the X-ray observations are corroborated by the detection of TeV gamma -rays from three of these remnants. The recent launches of the Chandra and XMM-Newton Observatories provide powerful new probes for regions of shock acceleration in young supernova remnants. The status of the X-ray observations and their implications are reviewed, including some early Chandra results. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Petre, R (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 28 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0094-243X BN 0-7354-0001-6 J9 AIP CONF PROC PY 2001 VL 565 BP 360 EP 368 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA BS29B UT WOS:000169367800053 ER PT J AU Fox-Rabinovitz, MS AF Fox-Rabinovitz, MS TI Simulation of anomalous regional climate events with a variable-resolution stretched-grid GCM SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SHALLOW-WATER EQUATIONS; NUMERICAL WEATHER PREDICTION; GENERAL-CIRCULATION MODELS; PRIMITIVE EQUATIONS; GLOBAL-MODEL; SYSTEM; PARAMETERIZATIONS; FORMULATION; DYNAMICS; PROJECT AB The stretched-grid approach provides an efficient downscaling and consistent interactions between global and regional scales due to using one variable-resolution model for integrations. It is a workable alternative to the widely used nested-grid approach introduced over a decade ago as a pioneering step in regional climate modeling. A variable-resolution finite-difference GCM (general circulation model) employing a stretched grid, with enhanced resolution over the United States as the area of interest, is used for simulating two anomalous regional climate events, the U.S. summer drought of 1988 and the U.S. summer flood of 1993. The special mode of integration using a stretched-grid GCM and data assimilation system is developed which allows for imitating the nested-grid framework within a stretched-grid approach. The mode is useful for intercomparison purposes and for underlining the differences between these two approaches. The 1988 and 1993 integrations are performed for the 2 month period starting from mid-May. Regional resolutions used in most of the experiments is 60 km. The major goal and the result of the study is obtaining the efficient downscaling over the area of interest. The monthly mean prognostic regional fields for the stretched-grid integrations are remarkably close to those of the verifying analyses. Simulated precipitation patterns are successfully verified against gauge precipitation observations. The impact of finer 40 km regional resolution is investigated for the 1993 integration and an example of recovering subregional precipitation is presented. The obtained results show that the global variable-resolution stretched-grid approach is a viable candidate for regional and subregional climate studies and applications. C1 Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Univ Maryland, ESSIC, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Fox-Rabinovitz, MS (reprint author), Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. NR 59 TC 12 Z9 12 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0747-7309 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD DEC 27 PY 2000 VL 105 IS D24 BP 29635 EP 29645 DI 10.1029/2000JD900650 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 391LY UT WOS:000166358500026 ER PT J AU Smith, DD Sibille, Z Cronise, RJ Hunt, AJ Oldenburg, SJ Wolfe, D Halas, NJ AF Smith, DD Sibille, Z Cronise, RJ Hunt, AJ Oldenburg, SJ Wolfe, D Halas, NJ TI Effect of microgravity on the growth of silica nanostructures SO LANGMUIR LA English DT Article ID AGGREGATION AB The effect of microgravity on the growth of silica nanoparticles via the sol-gel route is profound. In four different recipes that typically produce silica nanoparticles in unit gravity, low-density gel structures were instead formed in microgravity. These observations suggest that microgravity reduces the particle growth rate, allowing unincorporated species to form aggregates and ultimately gel. Hence microgravity favors the formation of more rarefied structures, providing a bias toward diffusion-limited aggregation. Moreover, these results add to evidence that the growth of silica nanoparticles occurs not simply through monomer addition but by the attachment of smaller primary particles and aggregates. C1 NASA, George C Marshall Space Flight Ctr, Biotechnol Sci Grp, Micrograv Sci & Applicat Dept, Huntsville, AL 35812 USA. RP Smith, DD (reprint author), NASA, George C Marshall Space Flight Ctr, Biotechnol Sci Grp, Micrograv Sci & Applicat Dept, SD-48, Huntsville, AL 35812 USA. NR 26 TC 14 Z9 14 U1 0 U2 9 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0743-7463 J9 LANGMUIR JI Langmuir PD DEC 26 PY 2000 VL 16 IS 26 BP 10055 EP 10060 DI 10.1021/la000643s PG 6 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 388DG UT WOS:000166161700017 ER PT J AU Walsh, P Kalia, RK Nakano, A Vashishta, P Saini, S AF Walsh, P Kalia, RK Nakano, A Vashishta, P Saini, S TI Amorphization and anisotropic fracture dynamics during nanoindentation of silicon nitride: A multimillion atom molecular dynamics study SO APPLIED PHYSICS LETTERS LA English DT Article ID INDENTATION; SIMULATION; ADHESION; SURFACES; GROWTH; MEMORY; ALPO4; PHASE AB Molecular dynamics simulations of nanoindentation of 10 million atom alpha -Si(3)N(4) films using a rigid indenter are reported. Local pressure distributions and configuration images of the plastically deformed region are presented. Residual tensile pressures correspond to voids and cracks that separate regions of compacted, plastically deformed material and elastically recovered crystalline material. Structural analysis shows that pile-up material on the surface and deformed material under the indenter is amorphous. With this indenter geometry, Si(3)N(4) deforms primarily by amorphization, which is arrested by cracking at the indenter corners and piling-up of material along the indenter sides. Indentation fracture exhibits anisotropic behavior consistent with the orientation-dependent fracture toughness values. (C) 2000 American Institute of Physics. [S0003- 6951(00)01048-2]. C1 Louisiana State Univ, Dept Phys & Astron, Concurrent Comp Lab Mat Simulat, Baton Rouge, LA 70803 USA. Louisiana State Univ, Dept Comp Sci, Baton Rouge, LA 70803 USA. NASA, Ames Res Ctr, Numer Aerosp Simulat Facil, Moffett Field, CA 94035 USA. RP Walsh, P (reprint author), Louisiana State Univ, Dept Phys & Astron, Concurrent Comp Lab Mat Simulat, Baton Rouge, LA 70803 USA. EM walsh@phys.lsu.edu NR 19 TC 37 Z9 37 U1 1 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 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD DEC 25 PY 2000 VL 77 IS 26 BP 4332 EP 4334 AR PII [S0003-6951(00)01048-2] DI 10.1063/1.1328371 PG 3 WC Physics, Applied SC Physics GA 387JY UT WOS:000166120500030 ER PT J AU Gilmore, MS Castano, R Mann, T Anderson, RC Mjolsness, ED Manduchi, R Saunders, RS AF Gilmore, MS Castano, R Mann, T Anderson, RC Mjolsness, ED Manduchi, R Saunders, RS TI Strategies for autonomous rovers at Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID PATHFINDER LANDING SITE; SPECTRAL REFLECTANCE; CARBONATE MINERALS; MARTIAN SURFACE; DEPOSITS; SEARCH; ROCKS; LIFE; SOIL; CALIFORNIA AB The science return from future robotic exploration of the Martian surface can be enhanced by performing routine processing using onboard computers. This can be accomplished by using software that recognizes scientifically relevant surface features from imaging and other data and prioritizes the data for return transmission to Earth. Two algorithms have been designed and evaluated with field data to identify the properties of the environment that can be reliably detected with onboard imaging and multispectral observation. One algorithm identifies variations in surface textures in images and successfully distinguishes between rocks and soil and between differences in grain size in a rock of a single composition. A second algorithm utilizes a neural net to recognize selected carbonate minerals from spectral reflectance data and successfully identifies carbonates from a set of spectra collected in the field. These types of algorithms will contribute to the efficiency of a landed instrument suite given the limited resources of time, data storage, and available communications opportunities. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wesleyan Univ, Dept Earth & Environm Sci, 265 Church St, Middletown, CT 06459 USA. EM mgilmore@wesleyan.edu; rebecca.castano@jpl.nasa.gov; tobias.mann@jpl.nasa.gov; robert.anderson@jpl.nasa.gov; eric.mjolsness@jpl.nasa.gov; roberto.manduchi@jpl.nasa.gov; saunders@jpl.nasa.gov RI Gilmore, Martha/G-5856-2011 NR 48 TC 15 Z9 15 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9097 EI 2169-9100 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD DEC 25 PY 2000 VL 105 IS E12 BP 29223 EP 29237 DI 10.1029/2000JE001275 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 393PM UT WOS:000166478900002 ER PT J AU Bills, BG Ray, RD AF Bills, BG Ray, RD TI Galilean satellite obliquities SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INTERNAL STRUCTURE; TIDAL DISSIPATION; ORBITAL RESONANCE; IO; EUROPA; EPHEMERIDES; LIBRATIONS; EVOLUTION; GANYMEDE; FEATURES AB The obliquities, or angular separations between spin pole and orbit pole, for the Galilean satellites of Jupiter are all small but nonzero. We present calculations of the expected obliquity values based on the well known orbital parameters and recent estimates of the moments of inertia of the satellites, under the assumption that all are in Cassini states. The nonzero obliquities of these bodies are dynamically significant because they imply the existence of components of tidal and librational stress and dissipation which have been previously ignored. In addition, accurate observational determination of the obliquities will provide more direct estimates of the moments of inertia of these bodies than are currently available. C1 Univ Calif San Diego, Scripps Inst Oceanog, Inst Geophys & Planetary Phys, La Jolla, CA 92093 USA. NASA, Goddard Space Flight Ctr, Space Geodesy Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Geodynam Branch, Greenbelt, MD 20771 USA. RP Bills, BG (reprint author), Univ Calif San Diego, Scripps Inst Oceanog, Inst Geophys & Planetary Phys, La Jolla, CA 92093 USA. RI Bills, Bruce/C-1156-2008; Ray, Richard/D-1034-2012 NR 43 TC 5 Z9 5 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD DEC 25 PY 2000 VL 105 IS E12 BP 29277 EP 29282 DI 10.1029/2000JE001248 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 393PM UT WOS:000166478900004 ER PT J AU Brandt, S Correll, R Gomez, R Huq, M Laguna, P Lehner, L Marronetti, P Matzner, RA Neilsen, D Pullin, J Schnetter, E Shoemaker, D Winicour, J AF Brandt, S Correll, R Gomez, R Huq, M Laguna, P Lehner, L Marronetti, P Matzner, RA Neilsen, D Pullin, J Schnetter, E Shoemaker, D Winicour, J TI Grazing collisions of black holes via the excision of singularities SO PHYSICAL REVIEW LETTERS LA English DT Article ID BOUNDARY-CONDITIONS; INITIAL DATA; NUMERICAL RELATIVITY; EVOLUTION AB We present the first simulations of non-head-on (grazing collisions of binary black holes in which the singularities an excised from the simulation, initially equal mass m black holes (spinning or not) are separated by approximate to 10m and with impact parameter approximate to 2m. Evolutions to t approximate to 35m are obtained where two separate horizons are present far t approximate to 3.8m; then a single enveloping horizon forms indicating that the holes merged. Apparent horizon area estimates suggest gravitational radiation of about 2%-3% of the total mass. The evolutions end after a moderate amount of rime because of instabilities. C1 Penn State Univ, Ctr Gravitat Phys & Geometry, University Pk, PA 16802 USA. Univ Texas, Ctr Relat, Austin, TX 78712 USA. NASA, Washington, DC 20546 USA. Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA. Univ British Columbia, Dept Phys & Astron, Vancouver, BC V6T 1Z1, Canada. RP Penn State Univ, Ctr Gravitat Phys & Geometry, University Pk, PA 16802 USA. RI Neilsen, David/J-4862-2015; Gomez, Roberto/K-8912-2015; OI Neilsen, David/0000-0002-6142-5542; Gomez, Roberto/0000-0002-1357-456X; Schnetter, Erik/0000-0002-4518-9017; Pullin, Jorge/0000-0001-8248-603X NR 39 TC 71 Z9 71 U1 0 U2 0 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 EI 1079-7114 J9 PHYS REV LETT JI Phys. Rev. Lett. PD DEC 25 PY 2000 VL 85 IS 26 BP 5496 EP 5499 DI 10.1103/PhysRevLett.85.5496 PN 1 PG 4 WC Physics, Multidisciplinary SC Physics GA 387QD UT WOS:000166132500004 PM 11136030 ER PT J AU Hirabayashi, H Hirosawa, H Kobayashi, H Murata, Y Asaki, Y Avruch, IM Edwards, PG Fomalont, EB Ichikawa, T Kii, T Okayasu, R Wajima, K Inoue, M Kawaguchi, N Chikada, Y Bushimata, T Fujisawa, K Horiuchi, S Kameno, S Miyai, T Shibata, KM Shen, ZQ Uemoto, T Kasuga, T Nakajima, J Takahashi, Y Enome, S Morimoto, M Ellis, J Meier, DL Murphy, DW Preston, RA Smith, JG Wietfeldt, RD Benson, JM Claussen, MJ Flatters, C Moellenbrock, GA Romney, JD Ulvestad, JS Langston, GI Minter, AH D'Addario, LR Dewdney, PE Dougherty, SM Jauncey, DL Lovell, JEJ Tingay, SJ Tzioumis, AK Taylor, AR Cannon, WH Gurvits, LI Schilizzi, RT Booth, RS Popov, MV AF Hirabayashi, H Hirosawa, H Kobayashi, H Murata, Y Asaki, Y Avruch, IM Edwards, PG Fomalont, EB Ichikawa, T Kii, T Okayasu, R Wajima, K Inoue, M Kawaguchi, N Chikada, Y Bushimata, T Fujisawa, K Horiuchi, S Kameno, S Miyai, T Shibata, KM Shen, ZQ Uemoto, T Kasuga, T Nakajima, J Takahashi, Y Enome, S Morimoto, M Ellis, J Meier, DL Murphy, DW Preston, RA Smith, JG Wietfeldt, RD Benson, JM Claussen, MJ Flatters, C Moellenbrock, GA Romney, JD Ulvestad, JS Langston, GI Minter, AH D'Addario, LR Dewdney, PE Dougherty, SM Jauncey, DL Lovell, JEJ Tingay, SJ Tzioumis, AK Taylor, AR Cannon, WH Gurvits, LI Schilizzi, RT Booth, RS Popov, MV TI The VLBI space observatory programme and the radio-astronomical satellite HALCA SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE space vehicles : instruments; techniques : interferometric; radio continuum : galaxies ID BASE-LINE INTERFEROMETRY; LONG; CORRELATOR; TELESCOPE; TAPE; GHZ AB The radio astronomy satellite HALCA was launched by the Institute of Space and Astronautical Science in 1997 February to participate in Very Long Baseline Interferometry (VLBI) observations with arrays of ground radio telescopes. HALCA is the main element of the VLBI Space Observatory Programme (VSOP), a complex international endeavor involving over 25 ground radio telescopes, five tracking stations and three correlators. Simultaneous observations with HALCA's 8 meter diameter radio telescope and ground radio telescopes synthesize a radio telescope over twice the size of the Earth, enabling the highest resolution 1.6 GHz and 5 GHz images to be made. C1 Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. Natl Astron Observ, Mitaka, Tokyo 1818588, Japan. Hosei Univ, Dept Syst & Control Engn, Koganei, Tokyo 1848584, Japan. Commun Res Labs, Kashima, Ibaraki 3140012, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Radio Astron Observ, Socorro, NM 87801 USA. Natl Radio Astron Observ, Green Bank, WV 24944 USA. Natl Radio Astron Observ, Tucson, AZ 85721 USA. Natl Res Council Canada, Herzberg Inst Astrophys, Ottawa, ON K1A 0R6, Canada. Domin Radio Astrophys Observ, Penticton, BC V2A 6K3, Canada. Australia Telescope Natl Facil, Epping, NSW 2122, Australia. Univ Calgary, Dept Phys & Astron, Calgary, AB T2N 1N4, Canada. York Univ, Ctr Res Earth & Space Technol, N York, ON M3J 3K1, Canada. VLBI Europe, Joint Inst, NL-7991 PD Dwingeloo, Netherlands. Chalmers, Onsala Space Observ, S-43992 Onsala, Sweden. PN Lebedev Phys Inst, Ctr Astro Space, Moscow 117810, Russia. Kanagawa Univ, Dept English, Yokohama, Kanagawa 2218686, Japan. RP Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 2298510, Japan. RI Tingay, Steven/B-5271-2013; Popov, Mikhail/M-6118-2015 NR 58 TC 66 Z9 67 U1 1 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 DEC 25 PY 2000 VL 52 IS 6 BP 955 EP 965 DI 10.1093/pasj/52.6.955 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 388QR UT WOS:000166193500001 ER PT J AU Hirabayashi, H Fomalont, EB Horiuchi, S Lovell, JEJ Moellenbrock, GA Inoue, M Burke, BF Dewdney, PE Gurvits, LI Kobayashi, H Jauncey, DL Murata, Y McCulloch, P Preston, RA Avruch, IM Edwards, PG Dougherty, SM Scott, WK Frey, S Paragi, Z Kovalev, YA Popov, M Romney, JD Schilizzi, RT Shen, ZQ Nicolson, G Quick, J Costa, M Dodson, R Reynolds, JE Tzioumis, AK Tingay, SJ Hong, XY Liang, SG Huang, XY Wei, WR Trigilio, C Tuccari, G Nakajima, J Kawai, E Umemoto, T Miyaji, T Fujisawa, K Kawaguchi, N Kus, A Ghigo, F Salter, C Ghosh, T Kanevsky, B Slysh, V Gunn, A Burgess, P Carlson, B Del Rizzo, D Taylor, R Cannon, W Kameno, S Shibata, KM Benson, J Flatters, C Hale, A Lewis, C Langston, G Minter, A Miller, K Smith, J Wietfeldt, R Altunin, V Meier, DL Murphy, DW Resch, G Lister, ML Piner, BG Jenkins, R Border, J Gimeno, J AF Hirabayashi, H Fomalont, EB Horiuchi, S Lovell, JEJ Moellenbrock, GA Inoue, M Burke, BF Dewdney, PE Gurvits, LI Kobayashi, H Jauncey, DL Murata, Y McCulloch, P Preston, RA Avruch, IM Edwards, PG Dougherty, SM Scott, WK Frey, S Paragi, Z Kovalev, YA Popov, M Romney, JD Schilizzi, RT Shen, ZQ Nicolson, G Quick, J Costa, M Dodson, R Reynolds, JE Tzioumis, AK Tingay, SJ Hong, XY Liang, SG Huang, XY Wei, WR Trigilio, C Tuccari, G Nakajima, J Kawai, E Umemoto, T Miyaji, T Fujisawa, K Kawaguchi, N Kus, A Ghigo, F Salter, C Ghosh, T Kanevsky, B Slysh, V Gunn, A Burgess, P Carlson, B Del Rizzo, D Taylor, R Cannon, W Kameno, S Shibata, KM Benson, J Flatters, C Hale, A Lewis, C Langston, G Minter, A Miller, K Smith, J Wietfeldt, R Altunin, V Meier, DL Murphy, DW Resch, G Lister, ML Piner, BG Jenkins, R Border, J Gimeno, J TI The VSOP 5 GHz AGN survey I. Compilation and observations SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN LA English DT Article DE galaxies : active; galaxies : radio; radio sources : general; techniques : interferometric ID RADIO-SOURCES; VLBI SURVEY; SPACE VLBI AB The VSOP mission is a Japanese-led project to image radio sources with sub-milliarcsec resolution by correlating the signal from the orbiting 8-m telescope, HALCA, with a global array of telescopes. Twenty-five percent of the scientific time of this mission is devoted to a survey of 402 bright, small-diameter extra-galactic radio sources at 5 GHz. The major goals of the VSOP Survey are statistical in nature: to determine the brightness temperature and approximate structure; to provide a source list for use with future space VLBI missions; and to compare radio properties with other data throughout the EM spectrum. This paper describes: the compilation of a complete list of radio sources associated with active galactic nuclei (AGN); the selection of the subsample of sources to be observed with VSOP; the extensive ground resources used for the Survey; the status of the observations as of 2000 July; the data-analysis methods; and several examples of results from the VSOP Survey. More detailed results from the full sample will be given in future papers. C1 Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2298510, Japan. Natl Radio Astron Observ, Charlottesville, VA USA. Natl Astron Observ, Mitaka, Tokyo 1818588, Japan. Australia Telescope Natl Facil, Epping, NSW 2122, Australia. Natl Radio Astron Observ, Socorro, NM 87801 USA. MIT, Cambridge, MA 02139 USA. Natl Res Council Canada, Domin Radio Astron Observ, Penticton, BC, Canada. VLBI Europe, Joint Inst, NL-7991 PD Dwingeloo, Netherlands. Univ Tasmania, Hobart, Tas 7000, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calgary, Calgary, AB T2N 1N4, Canada. FOMI Satellite Geodet Observ, H-1373 Budapest, Hungary. PN Lebedev Phys Inst, Ctr Astro Space, Moscow 117810, Russia. Hartebeesthoek Radio Astron Observ, ZA-1740 Krugersdorp, South Africa. Shanghai Astron Observ, Shanghai 200030, Peoples R China. CNR, Ist Radioastron, I-96017 Noto, Italy. Commun Res Labs, Kashima, Ibaraki 3140012, Japan. Nicholas Copernicus Univ, Torun Ctr Astron, PL-87100 Torun, Poland. Natl Radio Astron Observ, Green Bank, WV 24944 USA. Natl Astron & Ionosphere Ctr, Arecibo Observ, Arecibo, PR 00612 USA. MERLIN, VLBI Natl Facil, Macclesfield SK11 9DL, Cheshire, England. York Univ, CRESTech, N York, ON M3J 1P3, Canada. Canberra Deep Space Commun Complex, Tidbinbilla, Australia. Goldstone Deep Space Commun Complex, Goldstone, CA USA. Madrid Deep Space Commun Complex, Robledo, Spain. RP Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 2298510, Japan. RI Tingay, Steven/B-5271-2013; Frey, Sandor/G-4465-2013; Kovalev, Yuri/N-1053-2015; Kanevsky, Boris/M-4137-2015; OI Frey, Sandor/0000-0003-3079-1889; Kanevsky, Boris/0000-0002-1697-7508; Tuccari, Gino/0000-0001-7175-1977; Paragi, Zsolt/0000-0002-5195-335X NR 24 TC 65 Z9 66 U1 1 U2 3 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 DEC 25 PY 2000 VL 52 IS 6 BP 997 EP 1014 DI 10.1093/pasj/52.6.997 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 388QR UT WOS:000166193500006 ER PT J AU Gornitz, V Fairbridge, RW AF Gornitz, V Fairbridge, RW TI The vulnerability of Venice SO SCIENCE LA English DT Letter ID LEVEL C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Ctr Climate Syst Res, New York, NY 10025 USA. RP Gornitz, V (reprint author), NASA, Goddard Inst Space Studies, New York, NY 10025 USA. NR 3 TC 3 Z9 3 U1 1 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD DEC 22 PY 2000 VL 290 IS 5500 BP 2259 EP 2260 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 385GQ UT WOS:000165995800021 ER PT J AU Fruchter, AS Pian, E Gibbons, R Thorsett, SE Ferguson, H Petro, L Sahu, KC Livio, M Caraveo, P Frontera, F Kouveliotou, C Macchetto, D Palazzi, E Pedersen, H Tavani, M van Paradijs, J AF Fruchter, AS Pian, E Gibbons, R Thorsett, SE Ferguson, H Petro, L Sahu, KC Livio, M Caraveo, P Frontera, F Kouveliotou, C Macchetto, D Palazzi, E Pedersen, H Tavani, M van Paradijs, J TI Hubble Space Telescope observations of the host galaxy of GRB 970508 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : active; galaxies : starburst; gamma rays : bursts; stars : formation ID GAMMA-RAY BURST; STAR-FORMING GALAXIES; GRB 970508; HIGH-REDSHIFT; LIGHT CURVES; RADIO AFTERGLOW; SPECTRAL DISTRIBUTIONS; OPTICAL COUNTERPART; EMISSION; ULTRAVIOLET AB We report on observations of the field of GRB 970508 made in 1998 early August, 454 days after outburst, with the STIS CCD camera on board the Hubble Space Telescope (HST). The images, taken in open filter (50CCD) mode, clearly reveal the presence of a galaxy that was overwhelmed in earlier (1997 June) HST images by emission from the optical transient (OT). The galaxy is regular in shape: after correcting for the HST/STIS PSF, it is well fitted by an exponential disk with a scale length of 0."046 +/- 0."006 and an ellipticity of 0.70 +/- 0.07. All observations are marginally consistent with a continuous decline in OT emission as t(-1.3) beginning 2 days after outburst; however, we find no direct evidence in the late-time HST image for emission from the OT, and the surface brightness profile of the galaxy is most regular if we assume that the OT emission is negligible, suggesting that the OT may have faded more rapidly at late times than is predicted by the power-law decay. Due to the wide bandwidth of the STIS clear mode, the estimated magnitude of the galaxy is dependent on the galaxy spectrum that is assumed. Using colors obtained from late-time ground-based observations to constrain the spectrum, we find V = 25.4 +/- 0.15, a few tenths of a magnitude brighter than earlier ground-based estimates that were obtained by observing the total light of the galaxy and the OT and then subtracting the estimated OT brightness, assuming that it fades as a single power law. This again suggests that the OT may have faded faster at late time than the power law predicts. The position of the OT agrees with that of the isophotal center of the galaxy to which, at the galaxy redshift z = 0.83, corresponds to an offset from the 0."01, center of the host of pc. This remarkable agreement raises the possibility that the gamma-ray burst less than or similar to 70 may have been associated with either an active galactic nucleus or a nuclear starburst. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. CNR, Ist Tecnol & Studio Radiaz Extraterr, I-40129 Bologna, Italy. Univ Calif Santa Cruz, Dept Astron & Astrophys, Santa Cruz, CA 95064 USA. CNR, Ist Fis Cosm & Tecnol Relat, I-20133 Milan, Italy. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. European Space Agcy, Dept Space Sci, Div Astrophys, F-75738 Paris 15, France. Copenhagen Univ Observ, DK-2100 Copenhagen A, Denmark. Columbia Univ, Columbia Astrophys Lab, New York, NY 10027 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. RP Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. RI Palazzi, Eliana/N-4746-2015; OI Palazzi, Eliana/0000-0002-8691-7666; Caraveo, Patrizia/0000-0003-2478-8018; Tavani, Marco/0000-0003-2893-1459; Pian, Elena/0000-0001-8646-4858 NR 46 TC 27 Z9 28 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD DEC 20 PY 2000 VL 545 IS 2 BP 664 EP 669 DI 10.1086/317870 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385UW UT WOS:000166023400010 ER PT J AU Points, SD Chu, YH Snowden, SL Staveley-Smith, L AF Points, SD Chu, YH Snowden, SL Staveley-Smith, L TI The supergiant shell LMC 2. II. Physical properties of the 10(6) K gas SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : bubbles; ISM : individual (LMC 2); X-rays : ISM ID LARGE-MAGELLANIC-CLOUD; SUPERNOVA-REMNANTS; X-RAYS; SUPERBUBBLES; EVOLUTION; BLOWOUT; ROSAT AB LMC 2 has the highest X-ray surface brightness of all known supergiant shells in the Large Magellanic Cloud (LMC). The X-ray emission peaks within the ionized filaments that define the shell boundary but also extends beyond the southern border of LMC 2 as an X-ray bright spur. ROSAT HRI images reveal the X-ray emission from LMC 2 and the spur to be truly diffuse, indicating a hot plasma origin. We have obtained ROSAT PSPC and ASCA SIS spectra to study the physical conditions of the hot (greater than or equal to 10(6) K) gas interior to LMC 2 and the spur. Raymond-Smith thermal plasma model fits to the X-ray spectra, constrained by H I 21 cm emission line measurements of the column density, show the plasma temperature of the hot gas interior of LMC 2 to be kT similar to 0.1-0.7 keV and of the spur to be kT similar to 0.1- 0.5 keV. We have compared the physical conditions of the hot gas interior to LMC 2 with those of other supergiant shells, superbubbles, and supernova remnants (SNRs) in the LMC. We find that our derived electron density for the hot gas inside LMC 2 is higher than the value determined for the supergiant shell LMC 4, comparable to the value determined for the superbubble N11, and lower than the values determined for the superbubble N44 and a number of SNRs. C1 Univ Illinois, Dept Astron, Urbana, IL 61801 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Univ Space Res Assoc, Greenbelt, MD 20771 USA. CSIRO, Australia Telescope Natl Facil, Epping, NSW 2121, Australia. RP Points, SD (reprint author), Univ Illinois, Dept Astron, 1002 W Green St, Urbana, IL 61801 USA. RI Staveley-Smith, Lister/A-1683-2011; Snowden, Steven/D-5292-2012 OI Staveley-Smith, Lister/0000-0002-8057-0294; NR 36 TC 8 Z9 8 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 20 PY 2000 VL 545 IS 2 BP 827 EP 841 DI 10.1086/317865 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385UW UT WOS:000166023400023 ER PT J AU Safi-Harb, S Petre, R Arnaud, KA Keohane, JW Borkowski, KJ Dyer, KK Reynolds, SP Hughes, JP AF Safi-Harb, S Petre, R Arnaud, KA Keohane, JW Borkowski, KJ Dyer, KK Reynolds, SP Hughes, JP TI A broadband X-ray study of supernova remnant 3C 397 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : individual (3C 397); stars : neutron; supernova remnants; X-rays : ISM ID FORMED DENSE SHELL; THERMAL CONDUCTION; MODELING W44; HOT INTERIOR; EMISSION; G11.2-0.3; PLASMAS; RADIO; ABSORPTION; G41.1-0.3 AB We present a broadband imaging and spectral study of the radio-bright supernova remnant (SNR) 3C 397 with ROSAT, ASCA, and RXTE. A bright X-ray spot seen in the HRI image hints at the presence of a pulsar-powered component and gives this SNR a composite X-ray morphology. Combined ROSAT and ASCA imaging shows that the remnant is highly asymmetric, with its X-ray emission peaking at the western lobe. The hard-band images obtained with the ASCA Gas Imaging Spectrometer show that much of the hard X-ray emission arises from the western lobe, associated with the SNR shell, with little hard X-ray emission associated with the central hot spot. The spectrum from 3C 397 is heavily absorbed and dominated by thermal emission with emission lines evident from Mg, Si, S, Ar and Fe. Single-component models fail to describe the X-ray spectrum, and at least two components are required : a soft component characterized by a low temperature and a large ionization timescale, and a hard component required to account for the Fe-K emission line and characterized by a much lower ionization timescale. We use a set of nonequilibrium ionization (NEI) models (Borkowski et al., in preparation), and find that the fitted parameters are robust. The temperatures from the soft and hard components are similar to0.2 keV and similar to1.6 keV respectively. The corresponding ionization timescales n(0) t (n(0) being the preshock hydrogen density) are similar to6 x 10(12) cm(-3) s and similar to6 x 10(10) cm(-3) s, respectively. The large n(0) t of the soft component suggests it is approaching ionization equilibrium; thus it can be Dt equally well with a collisional equilibrium ionization model. The spectrum obtained with the Proportional Counter Array (PCA) of RXTE is contaminated by emission from the Galactic ridge, with only similar to 15% of the count rate originating from 3C 397 in the 5-15 keV range. The PCA spectrum allowed us to confirm the thermal nature of the hard X-ray emission. A third component originating from a pulsar-driven component is possible, but the contamination of the source signal by the Galactic ridge did not allow us to determine its parameters or find pulsations from any hidden pulsar. We discuss the X-ray spectrum in the light of two scenarios : a young ejecta-dominated remnant of a core-collapse SN, and a middle-aged SNR expanding in a dense ISM. In the first scenario, the hot component arises from the SNR shell, and the soft component from an ejecta-dominated component. 3C 397 would be a young SNR (a few thousand years old), but intermediate in dynamical age between the young historical shells (like Tycho or Kepler), and those that are well into the Sedov phase of evolution (like Vela). In the second scenario, the soft component represents the blast wave propagating in a dense medium, and the hard component is associated with hot gas encountering a fast shock, or arising from thermal conduction. In this latter scenario, the SNR would be similar to twice as old, and transitioning into the radiative phase. The current picture we present in this paper is marginally consistent with this scenario, but it cannot be excluded. A spatially resolved spectroscopic study is needed to resolve the soft and hard components and differentiate between the two scenarios. Future Chandra and XMM data will also address the nature of the mysterious central (radio-quiet) X-ray spot. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. N Carolina Sch Sci & Math, Durham, NC USA. N Carolina State Univ, Raleigh, NC 27695 USA. Rutgers State Univ, Piscataway, NJ 08855 USA. RP Safi-Harb, S (reprint author), Univ Manitoba, Winnipeg, MB R3T 2N2, Canada. NR 43 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 20 PY 2000 VL 545 IS 2 BP 922 EP 938 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385UW UT WOS:000166023400032 ER PT J AU Monnier, JD Tuthill, PG Danchi, WC AF Monnier, JD Tuthill, PG Danchi, WC TI Diffraction-limited near-IR imaging at Keck reveals asymmetric, time-variable nebula around carbon star CIT 6 SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; stars : AGB and post-AGB; stars : winds, outflows; techniques : interferometric ID INFRARED STARS; WAVELENGTH DEPENDENCE; INTERFEROMETRY; TELESCOPE; OBJECTS; POLARIZATION; PHOTOMETRY; IRC+10216; MICRONS; PHASE AB We present multiepoch, diffraction-limited images of the nebula around the carbon star CIT 6 at 2.2 and 3.1 mum from aperture masking on the Keck I Telescope. The near-IR nebula is resolved into two main components, an elongated, bright feature showing time-variable asymmetry and a fainter component about 60 mas away with a cooler color temperature. These images were precisely registered (similar to 35 mas) with respect to recent visible images from the Hubble Space Telescope (Trammell et al.), which showed a bipolar structure in scattered light. The dominant near-IR feature is associated with the northern lobe of this scattering nebula, and the multiwavelength data set can be understood in terms of a bipolar dust shell around CIT 6. Variability of the near-IR morphology is qualitatively consistent with previously observed changes in red polarization, caused by varying illumination geometry due to nonuniform dust production. The blue emission morphology and polarization properties cannot be explained by the above model alone, but require the presence of a wide binary companion in the vicinity of the southern polar lobe. The physical mechanisms responsible for the breaking of spherical symmetry around extreme carbon stars, such as CIT 6 and IRC +10216, remain uncertain. C1 Smithsonian Astrophys Observ, Cambridge, MA 02138 USA. Univ Sydney, Sch Phys, Chatterton Astron Dept, Sydney, NSW 2006, Australia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RP Smithsonian Astrophys Observ, MS 42,60 Garden St, Cambridge, MA 02138 USA. EM jmonnier@cfa.harvard.edu; gekko@physics.usyd.edu.au; wcd@ssl.berkeley.edu NR 34 TC 35 Z9 35 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 DEC 20 PY 2000 VL 545 IS 2 BP 957 EP 964 DI 10.1086/317857 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385UW UT WOS:000166023400035 ER PT J AU Bohm-Vitense, E Carpenter, KG Robinson, RD AF Bohm-Vitense, E Carpenter, KG Robinson, RD TI Ultraviolet emission lines in Ba and non-Ba giants SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : chemically peculiar; stars : chromospheres ID WHITE-DWARF COMPANION; BARIUM STARS; BINARY NATURE; ABUNDANCES; NITROGEN; ELEMENTS; REGIONS; MODELS; CARBON AB With the Hubble Space Telescope (HST) and the Goddard High Resolution Spectrograph we have observed four barium and three weak barium stars in the ultraviolet spectral region, together with two nonpeculiar giant standard stars. An additional suspected Ba star was observed with HST and the Space Telescope Imaging Spectrograph. In the H-R diagram, three of the observed Ba stars lie on the same evolutionary tracks as the Hyades giants. Using International Ultraviolet Explorer (IUE) spectra of previously studied giants together with our HST spectra, we investigate whether the chromospheric and transition layer emission-line spectra of the Ba stars are different from those of nonpeculiar giants and from those of giants with peculiar carbon and/or nitrogen abundances. Except for the Ba star HD 46407 and the suspected Ba star HD 65699, the Ba star and mild Ba star emission-line fluxes are, for a given effective temperature and for a given luminosity, lower than those for the nonpeculiar giants observed with IUE. In comparison with the HST-observed standard stars, the C IV lambda 1550-to-C II lambda 1335 line flux ratios are smaller, but not necessarily so in comparison with all IUE-observed nonpeculiar giants. However, the C IV-to-C II line flux ratios for the Ba stars decrease with increasing carbon abundances. This shows that the energy balance in the lower transition layer is influenced by the carbon abundance. The temperature gradient appears to be smaller in the C II line-emitting region. There does not seem to be a difference in chromospheric electron densities for the Ba and non-Ba stars, though this result is rather uncertain. C1 Univ Washington, Dept Astron, Seattle, WA 98195 USA. NASA, Goddard Space Flight Ctr, LASP, Greenbelt, MD 20771 USA. Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. RP Bohm-Vitense, E (reprint author), Univ Washington, Dept Astron, Seattle, WA 98195 USA. NR 28 TC 1 Z9 1 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 20 PY 2000 VL 545 IS 2 BP 992 EP 999 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385UW UT WOS:000166023400039 ER PT J AU Laughlin, G AF Laughlin, G TI Mining the metal-rich stars for planets SO ASTROPHYSICAL JOURNAL LA English DT Article DE catalogs; planetary systems; stars : abundances ID EXTRASOLAR GIANT PLANETS; SOLAR NEIGHBORHOOD; PARENT STARS; MISSION; SYSTEMS; EVOLUTION; COMPANION; VELOCITY; KEPLER; DWARF AB We examine the correlation between stellar metallicity and the presence of short-period planets. It appears that approximately 1% of dwarf stars in the solar neighborhood harbor short-period planets characterized by near-circular orbits and orbital periods P < 20 days. However, among the most metal-rich stars (defined as having [Fe/H] > 0.2 dex), it appears that the fraction increases to 10%. Using the Hipparcos database and the Hauck & Mermilliod compilation of uvby photometry, we identify a sample of 206 metal-rich stars of spectral type K, G and F which have an enhanced probability of harboring short-period planets. Many of these stars would be excellent candidates for addition to radial velocity surveys. We have searched the Hipparcos epoch photometry for transiting planets within our 206 star catalog. We find that the quality of the Hipparcos data is not high enough to permit unambiguous transit detections. It is, however, possible to identify candidate transit periods. We then discuss various ramifications of the stellar metallicity-planet connection. First, we show that there is preliminary evidence for increasing metallicity with increasing stellar mass among known planet-bearing stars. This trend can be explained by a scenario in which planet-bearing stars accrete an average of 30 M-circle dot of rocky material after the gaseous protoplanetary disk phase has ended. We present dynamical calculations which suggest that a survey of metallicities of spectroscopic binary stars can be used to understand the root cause of the stellar metallicity-planet connection. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Laughlin, G (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 55 TC 80 Z9 80 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 20 PY 2000 VL 545 IS 2 BP 1064 EP 1073 DI 10.1086/317867 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385UW UT WOS:000166023400047 ER PT J AU Sanuki, T Motoki, M Matsumoto, H Seo, ES Wang, JZ Abe, K Anraku, K Asaoka, Y Fujikawa, M Imori, M Maeno, T Makida, Y Matsui, N Matsunaga, H Mitchell, J Mitsui, T Moiseev, A Nishimura, J Nozaki, M Orito, S Ormes, J Saeki, T Sasaki, M Shikaze, Y Sonoda, T Streitmatter, R Suzuki, J Tanaka, K Ueda, I Yajima, N Yamagami, T Yamamoto, A Yoshida, T Yoshimura, K AF Sanuki, T Motoki, M Matsumoto, H Seo, ES Wang, JZ Abe, K Anraku, K Asaoka, Y Fujikawa, M Imori, M Maeno, T Makida, Y Matsui, N Matsunaga, H Mitchell, J Mitsui, T Moiseev, A Nishimura, J Nozaki, M Orito, S Ormes, J Saeki, T Sasaki, M Shikaze, Y Sonoda, T Streitmatter, R Suzuki, J Tanaka, K Ueda, I Yajima, N Yamagami, T Yamamoto, A Yoshida, T Yoshimura, K TI Precise measurement of cosmic-ray proton and helium spectra with the BESS spectrometer SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; elementary particles ID ATMOSPHERIC NEUTRINOS; CROSS-SECTIONS; NUCLEI; FLUX; SCATTERING; ENERGIES; ELEMENTS; GEV/C AB We report cosmic-ray proton and helium spectra in energy ranges of 1-120 GeV nucleon(-1) and 1-54 GeV nucleon(-1), respectively, measured by a flight of the Balloon-borne Experiment with Superconducting Spectrometer (BESS) in 1998. The magnetic rigidity of the cosmic ray was reliably determined by highly precise measurement of the circular track in a uniform solenoidal magnetic field of 1 T. Those spectra were determined within overall uncertainties of +/-5% for protons and +/- 10% for helium nuclei including statistical and systematic errors. C1 Univ Tokyo, Bunkyo Ku, Tokyo 1130033, Japan. Univ Maryland, College Pk, MD 20742 USA. Kobe Univ, Kobe, Hyogo 6578501, Japan. High Energy Accelerator Res Org, KEK, Tsukuba, Ibaraki 3050801, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. RP Sanuki, T (reprint author), Univ Tokyo, Bunkyo Ku, Tokyo 1130033, Japan. RI MOTOKI, Masakazu/B-4212-2009 NR 37 TC 245 Z9 248 U1 1 U2 14 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 20 PY 2000 VL 545 IS 2 BP 1135 EP 1142 DI 10.1086/317873 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385UW UT WOS:000166023400054 ER PT J AU Laming, JM Kink, I Takacs, E Porto, JV Gillaspy, JD Silver, EH Schnopper, HW Bandler, SR Brickhouse, NS Murray, SS Barbera, M Bhatia, AK Doschek, GA Madden, N Landis, D Beeman, J Haller, EE AF Laming, JM Kink, I Takacs, E Porto, JV Gillaspy, JD Silver, EH Schnopper, HW Bandler, SR Brickhouse, NS Murray, SS Barbera, M Bhatia, AK Doschek, GA Madden, N Landis, D Beeman, J Haller, EE TI Emission-line intensity ratios in Fe XVII observed with a microcalorimeter on an electron beam ion trap SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic data; methods : laboratory; stars : individual (Capella); Sun : corona; techniques : spectroscopic; X-rays : general ID X-RAY-SPECTRA; SOLAR-FLARE; ACTIVE-REGION; POLARIZATION; PLASMAS; DENSITY AB We report new observations of emission line intensity ratios of Fe XVII under controlled experimental conditions, using the National Institute of Standards and Technology electron beam ion trap (EBIT) with a microcalorimeter detector. We compare our observations with collisional-radiative models using atomic data computed in distorted wave and R-matrix approximations, which follow the transfer of the polarization of level populations through radiative cascades. Our results for the intensity ratio of the 2p(6) S-1(0)-2p(5)3d P-1(1) 15.014 Angstrom line to the 2p(6) S-1(0)- 2p(5) 3d D-3(1) 15.265 Angstrom line are 2.94 +/- 0.18 and 2.50 +/- 0.13 at beam energies of 900 and 1250 eV, respectively. These results are not consistent with collisional-radiative models and support conclusions from earlier EBIT work at the Lawrence Livermore National Laboratory that the degree of resonance scattering in the solar 15.014 Angstrom line has been overestimated in previous analyses. Further observations assess the intensity ratio of the three lines between the 2p(6)-2p(5)3s configurations to the three lines between the 2p(6)-2p(5)3d configurations. Both R-matrix and distorted wave approximations agree with each other and our experimental results much better than most solar and stellar observations, suggesting that other processes not present in our experiment must play a role in forming the Fe XVII spectrum in solar and astrophysical plasmas. C1 USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. Natl Inst Stand & Technol, Gaithersburg, MD 20899 USA. MIT, Cambridge, MA 02139 USA. Univ Debrecen, H-4026 Debrecen, Hungary. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Osservatorio Astron GS Vaiana, I-90134 Palermo, Italy. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. RP Laming, JM (reprint author), USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. RI Bandler, Simon/A-6258-2010; OI Bandler, Simon/0000-0002-5112-8106; Brickhouse, Nancy/0000-0002-8704-4473 NR 31 TC 71 Z9 72 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 20 PY 2000 VL 545 IS 2 BP L161 EP L164 DI 10.1086/317876 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393EL UT WOS:000166456200021 ER PT J AU Zhang, B Xu, RX Qiao, GJ AF Zhang, B Xu, RX Qiao, GJ TI Nature and nurture: A model for soft gamma-ray repeaters SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; dense matter; gamma rays : bursts; pulsars : general; stars : neutron ID MAGNETIZED NEUTRON-STARS; STRANGE STARS; QUARK MATTER; X-RAY; COMET CLOUDS; BURSTS; SGR-1900+14; EMISSION AB During supernova explosions, strange stars with almost bare quark surfaces may be formed. Under certain conditions, these stars could be rapidly spun down by the torque exerted by the fossil disks formed from the fallback materials. They may also receive large kicks and hence have large proper-motion velocities. When these strange stars pass through the spherical "Oort" comet cloud formed during the presupernova era, they will capture some small-scale comet clouds and collide with some comet-like objects occasionally. These impacts can account for the repeating bursts as observed from the soft gamma repeaters. According to this picture, it is expected that SGR 1900+14 will become active again during 2004-2005. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Peking Univ, CAS PKU Beijing Astrophys Ctr, Beijing 100871, Peoples R China. Peking Univ, Dept Astron, Beijing 100871, Peoples R China. CCAST, World Lab, Beijing 100080, Peoples R China. RP Zhang, B (reprint author), Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16803 USA. NR 53 TC 27 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 20 PY 2000 VL 545 IS 2 BP L127 EP L130 DI 10.1086/317889 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393EL UT WOS:000166456200013 ER PT J AU Dodelson, S Kaplinghat, M Stewart, E AF Dodelson, S Kaplinghat, M Stewart, E TI Solving the coincidence problem: Tracking oscillating energy SO PHYSICAL REVIEW LETTERS LA English DT Article ID COLD DARK-MATTER; MICROWAVE BACKGROUND ANISOTROPY; COSMOLOGICAL CONSTANT; UNIVERSE; LAMBDA; MODELS; CONSTRAINTS; STATE; CONSEQUENCES; PARAMETERS AB Recent cosmological observations strongly suggest that the Universe is dominated by an unknown form of energy with negative pressure. Why is this dark energy density of order the critical density today? We propose that the dark energy has periodically dominated in the past so that its preponderance toda; is natural. We illustrate this paradigm with a model potential and show that its predictions are consistent with all observations. C1 NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Chicago, Enrico Fermi Inst, Dept Astron & Astrophys, Chicago, IL 60637 USA. Korea Adv Inst Sci & Technol, Dept Phys, Taejon 305701, South Korea. RP Dodelson, S (reprint author), NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, POB 500, Batavia, IL 60510 USA. RI Stewart, Ewan/C-1565-2011 NR 50 TC 128 Z9 129 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 DEC 18 PY 2000 VL 85 IS 25 BP 5276 EP 5279 DI 10.1103/PhysRevLett.85.5276 PG 4 WC Physics, Multidisciplinary SC Physics GA 383LN UT WOS:000165884200004 PM 11135975 ER PT J AU Manney, GL Michelsen, HA Irion, FW Toon, GC Gunson, MR Roche, AE AF Manney, GL Michelsen, HA Irion, FW Toon, GC Gunson, MR Roche, AE TI Lamination and polar vortex development in fall from ATMOS long-lived trace gases observed during November 1994 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OZONE LAMINAE; WATER-VAPOR; ATMOS/ATLAS-3 MEASUREMENTS; STRATOSPHERIC ABUNDANCES; TRAJECTORY CALCULATIONS; NORTHERN STRATOSPHERE; POTENTIAL VORTICITY; WAVE BREAKING; EARLY WINTER; CLIMATOLOGY AB Long-lived trace-gas profiles observed by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument around the developing polar vortex (the "protovortex") during early November 1994 show distinctive inversions (laminae). High-resolution profiles calculated using a reverse trajectory (RT) model reproduce the majority of these laminae, demonstrating that most of these features arise from advection by the large-scale winds. The relationship between CH(4) and N(2)O sampled in filaments of low-latitude air changes from the canonical midlatitude correlation to one typical of tropical air, confirming the identification of tropical laminae, N(2)O/CH(4) correlations for laminae in vortex filaments indicate that enough confined descent and mixing has already occurred in the middle and upper stratosphere by early November to alter the tracer relationship in the protovortex from that in midlatitudes. Distributions of laminae in ATMOS observations agree with regions of greater or less filamentation seen in high-resolution RT maps. There is a deep minimum in laminae occurrence between 30 degrees and 90 degreesE at all levels, extending to about 150 degreesE above similar to 35 km. Maxima in lamination in the lower stratosphere near 90 degrees -150 degreesE and 210 degrees -270 degreesE are associated with the main regions where tropical air is drawn up around the developing vortex. Continuous filamentation associated with the developing vortex and anticyclone in early November 1994 shows that transport and mixing processes previously reported during winter are already important during fall. C1 New Mexico Highlands Univ, Dept Phys, Las Vegas, NM 87701 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Sandia Natl Labs, Livermore, CA 94551 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. RP Manney, GL (reprint author), New Mexico Highlands Univ, Dept Phys, Las Vegas, NM 87701 USA. EM manney@mls.jpl.nasa.gov NR 38 TC 30 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD DEC 16 PY 2000 VL 105 IS D23 BP 29023 EP 29038 DI 10.1029/2000JD900428 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 389UQ UT WOS:000166257400010 ER PT J AU Pierce, RB Al-Saadi, JA Eckman, RS Fairlie, TD Grose, WL Kleb, MM Natarajan, M Olson, JR AF Pierce, RB Al-Saadi, JA Eckman, RS Fairlie, TD Grose, WL Kleb, MM Natarajan, M Olson, JR TI Dynamical climatology of the NASA Langley Research Center Interactive Modeling Project for Atmospheric Chemistry and Transport (IMPACT) model SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; CUMULUS CONVECTION; DATA ASSIMILATION; TOTAL OZONE; STRATOSPHERE; TROPOSPHERE; SYSTEM; CYCLE; FLOW AB A comparison of the NASA Langley Research Center (LaRC) Interactive Modeling Project for Atmospheric Chemistry and Transport (IMPACT) model's dynamical characteristics with assimilated data sets and observations is presented to demonstrate the ability of the model to represent the dynamical characteristics of Earth's troposphere and stratosphere, The LaRC IMPACT model is a coupled chemical/dynamical general circulation model (GCM) of the Earth's atmosphere extending from the surface to the lower mesosphere. It has been developed as a tool for assessing the effects of chemical, dynamical, and radiative coupling in the stratosphere on the Earth's climate. The LaRC IMPACT model winds and temperatures are found to be in fairly good agreement with Upper Atmospheric Research Satellite (UARS) United Kingdom Meteorological Office (UKMO) assimilated winds and temperatures in the lower stratosphere. The model upper stratospheric zonal mean temperatures are also in good agreement with the UARS-UKMO climatology except for a cold winter pole which results from the upward extension of the cold vortex temperatures and an elevated winter stratopause in the model. The cold pole bias is consistent with the overprediction of the winter stratospheric jet strength, and is characteristic of stratospheric GCMs in general. The model northern and southern hemisphere stratospheric eddy heat and momentum fluxes are within the expected interannual variability of the UARS-UKMO climatology. The combined effects of water vapor transport, radiative, convective, and planetary boundary layer parameterizations are shown to produce tropospheric winds and circulation statistics that are in good agreement with the UARS-UKMO climatology, although the model tropopause and upper tropospheric temperatures are generally cold relative to the UARS-UKMO temperatures. Comparisons between the model and UARS-UKMO climatology indicate that the model does a reasonable job in reproducing the frequency of observed synoptic-scale storms during the northern and southern hemisphere winters. Generally good agreement is found between the model and observations in the distribution of outgoing longwave radiation and precipitable water. However, the model precipitation and cloud distributions are influenced by spectral truncation errors which indicate that the T32 spectral resolution of the model is probably not adequate to accurately represent coupling between localized convection and large-scale water vapor transport. The agreement between the observed and model stratospheric circulation and temperatures, reasonableness of the model stratospheric wave driving, and stability of the model climatology provides confidence that the LaRC IMPACT model is appropriate for multiyear coupled radiation/chemistry/dynamics studies of the stratosphere. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, Hampton, VA 23681 USA. EM r.b.pierce@larc.nasa.gov RI Pierce, Robert Bradley/F-5609-2010 OI Pierce, Robert Bradley/0000-0002-2767-1643 NR 47 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 EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD DEC 16 PY 2000 VL 105 IS D23 BP 29109 EP 29134 DI 10.1029/2000JD900248 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 389UQ UT WOS:000166257400017 ER PT J AU Herman, JR Piacentini, RD Ziemke, J Celarier, E Larko, D AF Herman, JR Piacentini, RD Ziemke, J Celarier, E Larko, D TI Interannual variability of ozone and UV-B ultraviolet exposure SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID QUASI-BIENNIAL OSCILLATION; SOLAR-ACTIVITY; TOMS DATA; REFLECTIVITY; STRATOSPHERE; TEMPERATURE; SURFACE AB Zonal averages of annual and seasonal averages of ozone amounts from Nimbus 7/TOMS (1979-1992) have been examined to estimate the systematic interannual variability of UV-B (390-320 nm) exposure to solar radiation between +/-60 degrees latitude. As shown from statistical modeling, clear-sky interannual UV-B changes can be ascribed mainly to the quasi-biennial oscillation (QBO) driven by stratospheric winds. The QBO oscillations can cause interannual changes in UV-B exposure of +/-15% at 300 nm and +/-5% at 310 nm at the equator and at middle latitudes. In addition to QBO effects, there are larger interannual changes in ozone and UV-B associated with dynamical effects at higher latitudes. When UV-B attenuation from clouds is included, the general latitudinal structure of the interannual variability is maintained. At the equator the interannual variability of ozone amounts and UV exposure caused by the combination of the 2.3 year QBO and annual cycles implies that there is about a 5 year periodicity in UV-B variability caused by dynamical effects. At higher latitudes the appearance of the interannual UV-B maximum is predicted by the QBO but without the regular periodicity. The QBO effects on UV-B irradiance are larger than the long-term changes caused by the decrease in ozone amounts. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Nacl Rosario, CONICET, Inst Fis Rosario, Fac Cs Exactas Ing & Agrim, RA-2000 Rosario, Santa Fe, Argentina. Observ Astron Rosario, RA-2000 Rosario, Santa Fe, Argentina. SGT Corp, Greenbelt, MD 20770 USA. Raytheon ITSS Corp, Lanham, MD 20706 USA. RP Herman, JR (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. EM herman@tparty.gsfc.nasa.gov OI Herman, Jay/0000-0002-9146-1632 NR 18 TC 15 Z9 15 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 DEC 16 PY 2000 VL 105 IS D23 BP 29189 EP 29193 DI 10.1029/2000JD900524 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 389UQ UT WOS:000166257400023 ER PT J AU Bauschlicher, CW Bakes, ELO AF Bauschlicher, CW Bakes, ELO TI Infrared spectra of polycyclic aromatic hydrocarbons (PAHs) SO CHEMICAL PHYSICS LA English DT Article ID IR EMISSION FEATURES; CATIONS AB Synthetic infrared spectra of some polycyclic aromatic hydrocarbons containing up to 54 carbon atoms are reported. The species studied include ovalene, circumcoronene, dicoronylene, and hexabenzocoronene. We report spectra for anions, neutrals, cations, and multiply charged cations. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, SETI, Moffett Field, CA 94035 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Space Technol Div, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 17 TC 46 Z9 46 U1 1 U2 13 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD DEC 15 PY 2000 VL 262 IS 2-3 BP 285 EP 291 DI 10.1016/S0301-0104(00)00310-4 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 380UN UT WOS:000165722000007 ER PT J AU Zhou, XY Tsurutani, BT Gonzalez, WD AF Zhou, XY Tsurutani, BT Gonzalez, WD TI The solar wind depletion (SWD) event of 26 April 1999: Triggering of an auroral "pseudobreakup" event SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID JANUARY 10; SPACECRAFT; MISSION AB The interplanetary solar wind depletion (SWD) event of 26 April 1999 and its magnetospheric consequences are examined. The SWD event is characterized by a solar wind density decrease from similar to3.0 to 0.7 cm(-3) leading to a solar wind ram pressure decrease from similar to2.0 to 0.2 nPa. This SWD onset is followed by a dipolarization of nightside magnetospheric fields. At approximately the same time, an auroral pseudo-breakup occurred in the near-midnight auroral zone. A model is presented to explain the pseudo-breakup as energy release by the tail magnetic field reconfiguration. The release of magnetic tension energy is estimated to have been similar to3.3 x 10(19) ergs, while the auroral energy was approximately 30 % of this value, similar to1.0 x 10(19) ergs. This result may imply that the magnetic field collapse led to direct particle acceleration through parallel electric fields. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Inst Pesquisas Espaciais, BR-12201 Sao Jose Dos Campos, SP, Brazil. RP Zhou, XY (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 12 TC 1 Z9 1 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 15 PY 2000 VL 27 IS 24 BP 4025 EP 4028 DI 10.1029/2000GL003805 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 390TB UT WOS:000166311700016 ER PT J AU Parks, G Brittnacher, M Chua, D Fillingim, M Germany, G Spann, J AF Parks, G Brittnacher, M Chua, D Fillingim, M Germany, G Spann, J TI Behavior of the aurora during 10-12 May, 1999 when the solar wind nearly disappeared SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The aurora was still active with occasional pseudobreakup events when the solar wind density diminished to unusually small densities (0.2 cc(-1)) during May 10-12, 1999. The aurora was observed at high magnetic latitudes indicating that the electron precipitation source moved northward as the geomagnetic activity decreased. The events we have studied indicate that the solar wind density alone is not the primary parameter that controls the auroral activity. The weak auroral activity was observed with 150 nT magnetic bays and when the interplanetary magnetic field (IMF) B-z was small and positive resulting in small epsilon parameter. A new auroral feature was observed on May 11, 1999, between 0900-2000 UT. The electron precipitation was energetic, uniform, and covered the region commonly identified as the polar cap. This precipitation lasted for more than 10 hours and was stable over time scales of tens of minutes. On May 12, as the solar wind began to recover, a prolonged period of dayside activity occurred and was followed by a typical aurora at 0500 UT. C1 Univ Washington, Geophys Program, Seattle, WA 98195 USA. Univ Alabama, CSPAR, Huntsville, AL 35899 USA. George C Marshall Space Flight Ctr, Huntsville, AL USA. RP Parks, G (reprint author), Univ Washington, Geophys Program, Seattle, WA 98195 USA. NR 4 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 15 PY 2000 VL 27 IS 24 BP 4033 EP 4036 DI 10.1029/2000GL000106 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 390TB UT WOS:000166311700018 ER PT J AU Kohel, J Keto, JW AF Kohel, J Keto, JW TI Energy disposal in the two-photon laser-assisted reaction in xenon and chlorine gas mixtures SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID XE(6S,P-3-2) METASTABLE ATOMS; CHARGE-TRANSFER; HARPOON REACTIONS; EXCITED-STATES; BOND FORMATION; DOPED XENON; SOLID XENON; XECL-STAR; + CL; 2-PHOTON AB The two-photon laser assisted reaction (LAR) in low pressure xenon and chlorine gas mixtures has been studied over a broad range of excitation wavelengths in order to characterize the role of the entrance channel in determining the vibrational state distribution of the reaction products. We measure a high degree of vibrational excitation in the XeCl* product, confirming observations from previous studies of the LAR of Xe+Cl-2 collision pairs [Ku , J. Phys. Chem. 87, 2989 (1983)], and in distinct contrast with the vibrationally cold excimer observed following laser excitation in molecular beam experiments [Boivineau , Chem. Phys. Lett. 128, 528 (1986)]. The mean vibrational energy in the XeCl excimer depends strongly on laser wavelength, increasing with decreasing wavelength. Moreover, an increasing fraction of the available energy from the reaction is observed as vibration in the XeCl* product as the laser is tuned toward shorter wavelengths. The reaction outcomes are interpreted in terms of a selectivity of initial conditions on the ionic potential surface that mediates the reactive collision. (C) 2000 American Institute of Physics. [S0021-9606(00)71447-4]. C1 Univ Texas, Dept Phys, Austin, TX 78712 USA. RP Kohel, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 41 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD DEC 15 PY 2000 VL 113 IS 23 BP 10551 EP 10559 DI 10.1063/1.1324976 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 378LC UT WOS:000165585000012 ER PT J AU Goldman, A Coffey, MT Stephen, TM Rinsland, CP Mankin, WG Hannigan, JW AF Goldman, A Coffey, MT Stephen, TM Rinsland, CP Mankin, WG Hannigan, JW TI Isotopic OCS from high-resolution balloon-borne and ground-based infrared solar absorption spectra SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID FOURIER-TRANSFORM SPECTROSCOPY; CARBONYL SULFIDE; COLUMN ABUNDANCES; TRENDS; STRATOSPHERE; AEROSOL; CM(-1); SINKS AB Isotopic lines of carbonyl sulfide, (OCS)-O-16-C-12-S-34 in the nu(3) region (band center 2061.446 cm(-1)) are identified for the first time in balloon-borne and ground-based high-resolution (0.003 cm(-1)) solar absorption spectra. A quantitative analysis of the balloon-borne data is reported. The isotopic abundance may reveal the origins of the carbonyl sulfide in the atmosphere. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Denver, Dept Phys & Astron, Denver, CO 80208 USA. Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO 80303 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Goldman, A (reprint author), Univ Denver, Dept Phys & Astron, 2112 E Wesley Ave, Denver, CO 80208 USA. NR 25 TC 13 Z9 13 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD DEC 15 PY 2000 VL 67 IS 6 BP 447 EP 455 DI 10.1016/S0022-4073(00)00012-1 PG 9 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 351HB UT WOS:000089150800003 ER PT J AU Lyapustin, AI Muldashev, TZ AF Lyapustin, AI Muldashev, TZ TI Generalization of Marshak boundary condition for non-Lambert reflection SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID SPHERICAL-HARMONICS; RADIATIVE-TRANSFER; SURFACE; SYSTEM AB In this paper we generalize the Marshak lower boundary condition in the method of spherical harmonics (MSH) for an arbitrary law of surface reflection. The obtained analytical solution is based on the bilinear interpolation of surface bidirectional reflection distribution function (BRDF). Recurrent formulas presented here allow to avoid numeric integration and calculate matrices of boundary conditions for arbitrary orders of azimuthal and Legendgre polynomial expansions of MSH. For practical applications, we have studied the effect of discretization of the BRDF angular grid on the accuracy of calculation of reflected diffuse radiance. Simulations conducted for a large number of vegetative covers, soils and sand, show that an accuracy of 0.2% can be achieved with M = 11 azimuthal harmonics at N = 21 grid knots in cosine of zenith angle. Calculations over a ruffled water surface are much more demanding. For wind speed v greater than or equal to 10 m/s, an accuracy of 0.2% requires discretization of M greater than or equal to 40, N greater than or equal to 51. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Space Res Inst, Alma Ata, Kazakhstan. RP Lyapustin, AI (reprint author), Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Mailcode 920, Greenbelt, MD 20771 USA. RI Lyapustin, Alexei/H-9924-2014 OI Lyapustin, Alexei/0000-0003-1105-5739 NR 10 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD DEC 15 PY 2000 VL 67 IS 6 BP 457 EP 464 DI 10.1016/S0022-4073(00)00014-5 PG 8 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 351HB UT WOS:000089150800004 ER PT J AU Vander Wal, RL Ticich, TM Curtis, VE AF Vander Wal, RL Ticich, TM Curtis, VE TI Directed synthesis of metal-catalyzed carbon nanofibers and graphite encapsulated metal nanoparticles SO JOURNAL OF PHYSICAL CHEMISTRY B LA English DT Article ID NANOTUBES; DECOMPOSITION; ETHYLENE; GROWTH; FIBERS; HYDROCARBONS; ACETYLENE; NICKEL; IRON; SOOT AB Directed synthesis of metal catalyzed carbon nanofibers and graphite encapsulated metal nanoparticles is demonstrated where the catalyst metal nanoparticles of Ni have been preformed prior to introduction into a reactive hydrocarbon growth environment. Control of the chemical environment by additives governs the type of product. Use of thiophene as an additive yields carbon nanofibers, whereas chlorobenzene as an additive produces encapsulated metal nanoparticles. Comparison of these results and those without any additive distinguishes the mechanism(s) by which each additive promotes nanotube or encapsulation, respectively. C1 NASA Glenn, NCMR, Cleveland, OH 44135 USA. Centenary Coll Louisiana, Dept Chem, Shreveport, LA 71134 USA. RP Vander Wal, RL (reprint author), NASA Glenn, NCMR, MS 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 38 TC 29 Z9 29 U1 3 U2 10 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5647 J9 J PHYS CHEM B JI J. Phys. Chem. B PD DEC 14 PY 2000 VL 104 IS 49 BP 11606 EP 11611 DI 10.1021/jp002025q PG 6 WC Chemistry, Physical SC Chemistry GA 383DU UT WOS:000165868500004 ER PT J AU Wang, X Wilson, D Muller, R Maker, P Psaltis, D AF Wang, X Wilson, D Muller, R Maker, P Psaltis, D TI Liquid-crystal blazed-grating beam deflector SO APPLIED OPTICS LA English DT Article ID DISPLAY AB A transmission-type nonmechanical multiple-angle beam-steering device that uses liquid-crystal blazed grating has been developed. Sixteen steering angles with a contrast ratio of 18 has been demonstrated. A detailed analysis of the Liquid-crystal and poly(methyl methacrylate) blazed-grating deflector was carried out to provide guidance during the deflector's development. A manufacturing offset compensation technique is proposed to improve the device's performance greatly. A hybrid approach utilizing electrically generated blazed grating combined with the cascading approach described here yields in excess of 500 deflecting angles. (C) 2000 Optical Society of America OCIS codes: 050.1970, 230.3720, 230.2090, 050.1940. C1 CALTECH, Dept Elect Engn, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. RP Wang, X (reprint author), CALTECH, Dept Elect Engn, Pasadena, CA 91125 USA. EM psaltis@caltech.edu NR 25 TC 77 Z9 85 U1 2 U2 10 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 DEC 10 PY 2000 VL 39 IS 35 BP 6545 EP 6555 DI 10.1364/AO.39.006545 PG 11 WC Optics SC Optics GA 380KH UT WOS:000165700700001 PM 18354668 ER PT J AU Blazejowski, M Sikora, M Moderski, R Madejski, GM AF Blazejowski, M Sikora, M Moderski, R Madejski, GM TI Comptonization of infrared radiation from hot dust by relativistic jets in quasars SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : jets; quasars : general; radiation mechanisms : nonthermal; X-rays : general ID ACTIVE GALACTIC NUCLEI; EXTRAGALACTIC RADIO-SOURCES; GAMMA-RAY OBSERVATIONS; HIGH-ENERGY FLARE; X-RAY; ELECTRON ACCELERATION; EGRET OBSERVATIONS; AMBIENT RADIATION; LOUD BLAZARS; EMISSION AB We demonstrate the importance of near-infrared radiation from hot dust for Compton cooling of electrons/positrons in quasar jets. In our model, we assume that the nonthermal radiation spectra observed in optically violent variable (OVV) quasars are produced by relativistic electrons/positrons accelerated in thin shells that propagate down the jet with relativistic speeds. We show that the Comptonization of the near-IR flux is likely to dominate the radiative output of OVV quasars in the energy range from tens of keV up to hundreds of MeV, where it exceeds that produced by Comptonization of the UV radiation reprocessed and rescattered in the broad emission line (BEL) region. The main reason for this lies in the fact that the jet encounters the ambient IR radiation over a relatively large distance as compared to the distance where the energy density of the BEL light peaks. In the soft to mid-energy X-ray band, the spectral component resulting from Comptonization of the near-IR radiation joins smoothly with the synchrotron self-Compton component, which may be responsible for the soft X-ray flux. At the highest observed gamma -ray energies, in the GeV range, Comptonization of broad emission lines dominates over other components. C1 Nicolaus Copernicus Astron Ctr, PL-00716 Warsaw, Poland. Univ Colorado, JILA, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20771 USA. RP Blazejowski, M (reprint author), Nicolaus Copernicus Astron Ctr, Bartycka 18, PL-00716 Warsaw, Poland. NR 64 TC 163 Z9 164 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP 107 EP 116 DI 10.1086/317791 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300011 ER PT J AU Arribas, S Colina, L Borne, KD AF Arribas, S Colina, L Borne, KD TI Merging process and tidal-induced star formation in the ultraluminous infrared galaxy IRAS 08572+3915 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (IRAS 08572-3915); galaxies : interactions; galaxies : nuclei; galaxies : starburst ID GAS KINEMATICS; STARBURSTS; MERGERS; SYSTEM AB Integral field optical spectroscopy using the INTEGRAL system, complemented with HST imaging, has been used to characterize the merging process giving rise to the ultraluminous infrared galaxy IRAS 08572+3915, the star formation along the tidal tails of the galaxy, and the nature of the nuclear ionizing sources deep within the galaxy. The overall morphology with two well-identified nuclei, the widespread star formation, and the unperturbed two-dimensional gas kinematics indicate that IRAS 08572+3915 is a dynamically young system formed by two disks' galaxies which are in the process of merging. The galaxies have a mass ratio of about 5, the brighter being a similar to0.5L* galaxy. The ionized gas distribution traces the presence of young (6 Myr) dust-enshrouded massive nuclear starbursts of 2 x 10(7) to 10(8) M.. Contrary to previous claims, and based on the two-dimensional extinction-corrected optical emission line ratios, there is no evidence for a LINER or Seyfert-like nucleus in either of the galaxies. This is unusual for a warm, ultraluminous, infrared galaxy like IRAS 08572+3915. Tidal-induced, star-forming knots, located at distances of about 7 kpc from the nuclei and along the tidal tails, are traced by the presence of bright [O III]-emitting regions. These knots, with ages of 5.5-6 Myr and masses of similar to 10(6) seem to M., represent a common phenomenon of the merging process; they are already detected in many other ultraluminous infrared galaxies, and tidal dwarf galaxies could be just the more massive manifestation of the same phenomenon. C1 Inst Astrofis Canarias, Tenerife 38200, Spain. Space Telescope Sci Inst, Baltimore, MD 21218 USA. ESA, Dept Space Sci, Div Astrophys, Paris, France. CSIC, Madrid, Spain. Fac Ciencias, CSIC, UC, Inst Fis Cantabria, Santander 39005, Spain. NASA, Goddard Space Flight Ctr, Raytheon Informat Technol & Sci Serv, Greenbelt, MD 20771 USA. RP Arribas, S (reprint author), Inst Astrofis Canarias, Via Lactea S-N, Tenerife 38200, Spain. NR 31 TC 18 Z9 18 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP 228 EP 233 DI 10.1086/317813 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300022 ER PT J AU Klose, S Stecklum, B Masetti, N Pian, E Palazzi, E Henden, AA Hartmann, DH Fischer, O Gorosabel, J Sanchez-Fernandez, C Butler, D Ott, T Hippler, S Kasper, M Weiss, R Castro-Tirado, A Greiner, J Bartolini, C Guarnieri, A Piccioni, A Benetti, S Ghinassi, F Magazzu, A Hurley, K Cline, T Trombka, J McClanahan, T Starr, R Goldstein, J Gold, R Mazets, E Golenetskii, S Noeske, K Papaderos, P Vreeswijk, PM Tanvir, N Oscoz, A Munoz, JA Ceron, JMC AF Klose, S Stecklum, B Masetti, N Pian, E Palazzi, E Henden, AA Hartmann, DH Fischer, O Gorosabel, J Sanchez-Fernandez, C Butler, D Ott, T Hippler, S Kasper, M Weiss, R Castro-Tirado, A Greiner, J Bartolini, C Guarnieri, A Piccioni, A Benetti, S Ghinassi, F Magazzu, A Hurley, K Cline, T Trombka, J McClanahan, T Starr, R Goldstein, J Gold, R Mazets, E Golenetskii, S Noeske, K Papaderos, P Vreeswijk, PM Tanvir, N Oscoz, A Munoz, JA Ceron, JMC TI The very red afterglow of GRB 000418: Further evidence for dust extinction in a gamma-ray burst host galaxy SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID 14 DECEMBER 1997; OPTICAL AFTERGLOW; X-RAY; INTERSTELLAR EXTINCTION; FIREBALL MODEL; LIGHT CURVES; GRB-970508; GRB-990510; ENVIRONMENT; COUNTERPART AB We report near-infrared and optical follow-up observations of the afterglow of the GRB 000418 starting 2.5 days after the occurrence of the burst and extending over nearly 7 weeks. GRB 000418 represents the second case for which the afterglow was initially identified by observations in the near-infrared. During the first 10 days its R-band afterglow was well characterized by a single power-law decay with a slope of 0.86. However, at later times the temporal evolution of the afterglow flattens with respect to a simple power-law decay. Attributing this to an underlying host galaxy, we find its magnitude to be R = 23.9 and an intrinsic afterglow decay slope of 1.22. The afterglow was very red with R-K approximate to 4 mag. The observations can be explained by an adiabatic, spherical fireball solution and a heavy reddening due to dust extinction in the host galaxy. This supports the picture that (long) bursts are associated with events in star-forming regions. C1 Thuringer Landessternwarte Tautenburg, D-07778 Tautenburg, Germany. CNR, Ist Tecnol & Studio Radiaz Extraterr, I-40129 Bologna, Italy. US Naval Observ, Flagstaff Stn, Flagstaff, AZ 86002 USA. Clemson Univ, Dept Phys & Astron, Clemson, SC 29634 USA. Inst Astrophys, D-07745 Jena, Germany. Univ Sternwarte, D-07745 Jena, Germany. Danish Space Res Inst, DK-2100 Copenhagen, Denmark. CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain. Astrophys Inst Potsdam, D-14482 Potsdam, Germany. Univ Bologna, Dipartmento Astron, I-40127 Bologna, Italy. Ctr Galileo Galilei, Telescopio Nazl Galileo, E-38700 Santa Cruz de La Palma, Canary Isl, Spain. INTA, LAEFF, E-28080 Madrid, Spain. Max Planck Inst Astron, D-69117 Heidelberg, Germany. Max Planck Inst Extraterr Phys, D-85748 Garching, Germany. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. AF Ioffe Phys Tech Inst, St Petersburg 194021, Russia. Univ Sternwarte, D-37083 Gottingen, Germany. Astron Inst Anton Pannekoehk, NL-1098 SJ Amsterdam, Netherlands. Joint Astron Ctr, Hilo, HI 96720 USA. Inst Astrofis Canarias, Tenerife, Spain. San Fernando Naval, Real Observ Armada, Cadiz, Spain. RP Klose, S (reprint author), Thuringer Landessternwarte Tautenburg, D-07778 Tautenburg, Germany. RI McClanahan, Timothy/C-8164-2012; Papaderos, Polychronis/M-4206-2013; Golenetskii, Sergey/B-3818-2015; Palazzi, Eliana/N-4746-2015; OI Papaderos, Polychronis/0000-0002-3733-8174; Benetti, Stefano/0000-0002-3256-0016; Palazzi, Eliana/0000-0002-8691-7666; Castro-Tirado, A. J./0000-0003-2999-3563; Pian, Elena/0000-0001-8646-4858 NR 70 TC 46 Z9 46 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP 271 EP 276 DI 10.1086/317816 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300026 ER PT J AU Sonneborn, G Tripp, TM Ferlet, R Jenkins, EB Sofia, UJ Vidal-Madjar, A Wozniak, PR AF Sonneborn, G Tripp, TM Ferlet, R Jenkins, EB Sofia, UJ Vidal-Madjar, A Wozniak, PR TI Spatial variability in the ratio of interstellar atomic deuterium to hydrogen. II. Observations toward gamma(2) Velorum and xi Puppis by the interstellar medium absorption profile spectrograph SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; ISM : abundances; ISM : evolution; stars : individual (gamma(2) V, xi Puppis); ultraviolet : ISM ID GALACTIC CHEMICAL EVOLUTION; BIG-BANG NUCLEOSYNTHESIS; IUE MEGA CAMPAIGN; ZETA-PUPPIS; MOLECULAR-HYDROGEN; ALPHA ABSORPTION; SPACE-TELESCOPE; ORFEUS-SPAS; D/H RATIO; H-I AB High-resolution far-ultraviolet spectra of the early-type stars gamma (2) Vel and zeta Pup were obtained to measure the interstellar deuterium abundances in these directions. The observations were made with the Interstellar Medium Absorption Profile Spectrograph (IMAPS) during the ORFEUS-SPAS II mission in 1996. IMAPS spectra cover the wavelength range 930-1150 Angstrom with lambda/Delta lambda similar to 80,000. The interstellar D I AZ features are resolved and cleanly separated from interstellar H I in the Ly delta and Ly epsilon profiles of both sight lines and also in the Ly gamma profile of zeta Pup. The D I profiles were modeled using a velocity template derived from several N I lines in the IMAPS spectra recorded at higher signal-to-noise ratio. To find the best D I column density, we minimized chi (2) for model D I profiles that included not only the N(D I) as a free parameter, but also the effects of several potential sources of systematic error, which were allowed to vary as free parameters. H I column densities were measured by analyzing Ly alpha absorption profiles in a large number of IUE high-dispersion spectra for each of these stars and applying this same chi (2)-minimization technique. Ultimately we found that D/H = 2.18(-0.3)(1+0.36) x 10(-5) for gamma (2) Vel and 1.42(-0.23)(+0.25) x 10(-5) for zeta Pup, values that contrast markedly with D/H derived in Paper I for delta Ori A (the stated errors are 90% confidence limits). Evidently, the atomic D/H ratio in the ISM, averaged over path lengths of 250-500 pc, exhibits significant spatial variability. Furthermore, the observed spatial variations in D/H do not appear to be anticorrelated with N/H, one measure of heavy-element abundances. We briefly discuss some hypotheses to explain the D/H spatial variability. Within the framework of standard big bang nucleosynthesis, the large value of D/H found toward gamma (2) Vel is equivalent to a cosmic baryon density of Omega (B) h(2) = 0.023 +/- 0.002 which we regard as an upper limit since there is no correction for the destruction of deuterium in stars. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Princeton Univ Observ, Princeton, NJ 08544 USA. Inst Astrophys Paris, F-75014 Paris, France. Whitman Coll, Dept Astron, Walla Walla, WA 99362 USA. RP Sonneborn, G (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 681, Greenbelt, MD 20771 USA. EM george.sonneborn@gsfc.nasa.gov; tripp@astro.princeton.edu; ferlet@iap.fr; ebj@astro.princeton.edu; sofiauj@whitman.edu; alfred@iap.fr; wozniak@astro.princeton.edu RI Jenkins, Edward/P-5684-2014 OI Jenkins, Edward/0000-0003-1892-4423 NR 77 TC 66 Z9 66 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 DEC 10 PY 2000 VL 545 IS 1 BP 277 EP 289 DI 10.1086/317799 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300027 ER PT J AU Almy, RC McCammon, D Digel, SW Bronfman, L May, J AF Almy, RC McCammon, D Digel, SW Bronfman, L May, J TI Distance limits on the bright X-ray emission toward the Galactic center: Evidence for a very hot interstellar medium in the Galactic X-ray bulge SO ASTROPHYSICAL JOURNAL LA English DT Article DE Galaxy : structure; ISM : clouds; ISM : structure; X-rays : ISM ID MILKY-WAY; LOOP-I; HALO; ABUNDANCES; GALAXY; CLOUDS; STARS; RIDGE; MAPS AB Observations of the diffuse X-ray background at energies similar to3/4 and 1.5 keV show a large region of enhanced emission around the Galactic center. The origin of this X-ray enhancement is not known, but the best candidates are the nearby Loop I superbubble and a Galactic X-ray bulge. To differentiate between these two possibilities, the distance scales to the X-ray-emitting material along the line of sight must be established. A mosaic of 13 ROSAT PSPC pointings in the direction of l similar to 337 degrees, b similar to4 degrees reveals X-ray shadows in the and 1.5 keV bands cast by a distant molecular cloud complex. Analysis of the shadows indicates that a large fraction (45% <^>9%) of the observed emission in this direction originates beyond the cloud complex, located at d similar to2 kpc. The implied surface brightness of this distant emission source can account for similar to 70% of the enhanced emission away from the absorption trough in the Galactic plane. This result indicates that the Loop I bubble cannot be the principal source of the enhanced X-ray emission, and suggests the existence of a bright X-ray source occupying the central region of the Galaxy, with a radial extent of similar to6 kpc and an X-ray luminosity of similar to 10(39) ergs s(-1). We examine some simple models of the emission region and compare them to the ROSAT all-sky survey. A thermal origin for the emission implies a plasma temperature of similar to 4x10(6) K and a total thermal energy in the range of 6-9x10(55) ergs. C1 Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Raytheon STX, Greenbelt, MD 20771 USA. Univ Chile, Dept Astron, Santiago, Chile. RP Almy, RC (reprint author), Univ Wisconsin, Dept Phys, 1150 Univ Ave, Madison, WI 53706 USA. RI Bronfman, Leonardo/H-9544-2013 OI Bronfman, Leonardo/0000-0002-9574-8454 NR 40 TC 36 Z9 36 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP 290 EP 300 DI 10.1086/317768 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300028 ER PT J AU Maran, SP Sonneborn, G Pun, CSJ Lundqvist, P Iping, RC Gull, TR AF Maran, SP Sonneborn, G Pun, CSJ Lundqvist, P Iping, RC Gull, TR TI Physical conditions in circumstellar gas surrounding SN 1987A 12 years after outburst SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; supernovae : individual (SN 1987A); supernova remnants ID EFFECTIVE COLLISION STRENGTHS; ULTRAVIOLET EMISSION-LINES; ELECTRON-IMPACT EXCITATION; INTERSTELLAR EXTINCTION; RING NEBULA; O-III; N-II; SN-1987A; TRANSITIONS; PROGENITOR AB Two-dimensional spectra of SN 1987A were obtained on 1998 November 14-15 (4282 days after outburst) with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). The slit sampled portions of the inner circumstellar ring at the east and west ansae as well as small sections of both the northern and southern outer rings. The temperature and density at these locations are estimated by nebular analysis of [N II], [O III], and [S II] emission-line ratios, and with time-dependent photoionization/recombination models. The results from these two methods are mutually consistent. The electron density in the inner ring is similar to 4000 cm(-3) for S II, with progressively lower densities for N II and O III. The electron temperatures determined from [N II] and [O III] line ratios are similar to 11,000 and similar to 22,000 K, respectively. These results are consistent with evolutionary trends in the circumstellar gas from similar measurements at earlier epochs. We find that emission lines from the outer rings come from gas of lower density (n(e) less than or similar to cm(-3)) than that which emits the same line in the inner ring. The N/O ratio appears to be the same in all three rings. Our results also suggest that the CNO abundances in the northern outer ring are the same as in the inner ring, contrary to earlier results. Physical conditions in the southern outer ring are less certain because of poorer signal-to-noise data. The STIS spectra also reveal a weak H alpha emission redshifted by similar to 100 km s(-1) at P.A. 103 degrees that coincides with the recently discovered new regions that are brightening. This indicates that the shock interaction in the southeast section of the inner ring commenced over a year before it became apparent in HST images. C1 NASA, Goddard Space Flight Ctr, Space Sci Directorate, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. Stockholm Observ, SE-13336 Saltsjobaden, Sweden. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. RP Maran, SP (reprint author), NASA, Goddard Space Flight Ctr, Space Sci Directorate, Code 600, Greenbelt, MD 20771 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 46 TC 21 Z9 26 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP 390 EP 398 DI 10.1086/317809 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300037 ER PT J AU Boroson, B O'Brien, K Horne, K Kallman, T Still, M Boyd, PT Quaintrell, H Vrtilek, SD AF Boroson, B O'Brien, K Horne, K Kallman, T Still, M Boyd, PT Quaintrell, H Vrtilek, SD TI Discovery of millihertz ultraviolet quasi-periodic oscillations in Hercules X-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : close; stars : individual (HZ Herculis); stars : oscillations; ultraviolet : stars; X-rays : stars ID TELESCOPE IMAGING SPECTROGRAPH; HZ HERCULIS; NEUTRON-STAR; 4U 1626-67; X-1; PULSAR; MASS; PULSATIONS; ACCRETION; SPECTRUM AB Observations of the ultraviolet continuum of the X-ray binary system Her X-1/HZ Herculis with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope (HST) show quasi-periodic oscillations (QPOs) at frequencies of 8 +/- 2 and 43 +/- 2 mHz, with rms amplitudes of 2% and 4% of the steady flux. Observations with the Keck Telescope confirm the presence of the higher frequency QPO in the optical continuum, with a rms amplitude of 1.6% +/- 0.2%. The QPOs are most prominent in the HST data near phi =0.5 (where phi =0 is the middle of the X-ray eclipse), suggesting that they arise not in the accretion disk but on the X-ray-heated face of the companion star. We discuss scenarios in which the companion star reprocesses oscillations in the disk which are caused by either Keplerian rotation or a beat frequency between the neutron star spin and Keplerian rotation at some radius in the accretion disk. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ St Andrews, St Andrews KY16 988, Fife, Scotland. Open Univ, Milton Keynes MK7 6AA, Bucks, England. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. RP Boroson, B (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM bboroson@falafel.gsfc.nasa.gov; kso@st-andrews.ac.uk; kdh1@st-and.ac.uk; tim@xstar.gsfc.nasa.gov; still@chunky.gsfc.nasa.gov; padi@dragons.gsfc.nasa.gov; H.Quaintrell@open.ac.uk; svrtilek@cfa.harvard.edu RI Boyd, Patricia/D-3274-2012 NR 42 TC 16 Z9 16 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 DEC 10 PY 2000 VL 545 IS 1 BP 399 EP 406 DI 10.1086/317786 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300038 ER PT J AU Corcoran, MF Fredericks, AC Petre, R Swank, JH Drake, SA AF Corcoran, MF Fredericks, AC Petre, R Swank, JH Drake, SA TI The X-ray spectral evolution of eta Carinae as seen by ASCA SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; stars : individual (eta Carinae); X-rays : stars ID SOURCE CATALOG; EMISSION; NEBULA; BINARY AB Using data from the ASCA X-ray observatory, we examine the variations in the X-ray spectrum of the supermassive star eta Carinae with an unprecedented combination of spatial and spectral resolution. We include data taken during the recent X-ray eclipse in 1997-1998, after recovery from the eclipse, and during and after an X-ray flare. We show that the eclipse variation in the X-ray spectrum is apparently confined to a decrease in the emission measure of the source. We compare our results with a simple colliding-wind binary model and find that the observed spectral variations are consistent with the binary model only if there is significant high-temperature emission far from the star and/or a substantial change in the temperature distribution of the hot plasma. If contamination in the 2-10 keV band is important, the observed eclipse spectrum requires an absorbing column in excess of 10(24) cm(-2) for consistency with the binary model, which may indicate an increase in (M) over dot from eta Carinae near the time of periastron passage. The flare spectra are consistent with the variability seen in nearly simultaneous RXTE observations and thus confirm that eta Carinae itself is the source of the flare emission. The variation in the spectrum during the flare seems confined to a change in the source emission measure. By comparing two observations obtained at the same phase in different X-ray cycles, we find that the current X-ray brightness of the source is slightly higher than the brightness of the source during the last cycle, perhaps indicative of a long-term increase in (M) over dot not associated with the X-ray cycle. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Corcoran, MF (reprint author), Univ Space Res Assoc, 7501 Forbes Blvd,Suite 206, Seabrook, MD 20706 USA. RI Swank, Jean/F-2693-2012 NR 34 TC 18 Z9 18 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP 420 EP 428 DI 10.1086/317806 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300040 ER PT J AU Baron, E Branch, D Hauschildt, PH Filippenko, AV Kirshner, RP Challis, PM Jha, S Chevalier, R Fransson, C Lundqvist, P Garnavich, P Leibundgut, B McCray, R Michael, E Panagia, N Phillips, MM Pun, CSJ Schmidt, B Sonneborn, G Suntzeff, NB Wang, L Wheeler, JC AF Baron, E Branch, D Hauschildt, PH Filippenko, AV Kirshner, RP Challis, PM Jha, S Chevalier, R Fransson, C Lundqvist, P Garnavich, P Leibundgut, B McCray, R Michael, E Panagia, N Phillips, MM Pun, CSJ Schmidt, B Sonneborn, G Suntzeff, NB Wang, L Wheeler, JC TI Preliminary spectral analysis of the Type II supernova 1999em SO ASTROPHYSICAL JOURNAL LA English DT Article DE radiative transfer; stars : atmospheres; supernovae : individual (SN 1999em) ID DISTANCE; ATMOSPHERES; SN-1993J; 1987A AB We have calculated fast direct spectral model fits to two early-time spectra of the Type II plateau SN 1999em, using the SYNOW synthetic spectrum code. The first is an extremely early blue optical spectrum and the second a combined Hubble Space Telescope and optical spectrum obtained one week later. Spectroscopically this supernova appears to be a normal Type II, and these fits are in excellent agreement with the observed spectra. Our direct analysis suggests the presence of enhanced nitrogen. We have further studied these spectra with the full non-LTE general model atmosphere code PHOENIX. While we do not find confirmation for enhanced nitrogen (nor do we rule it out), we do require enhanced helium. An even more intriguing possible line identification is complicated Balmer and He I lines, which we show falls naturally out of the detailed calculations with a shallow density gradient. We also show that very early spectra such as those presented here combined with sophisticated spectral modeling allow an independent estimate of the total reddening to the supernova, since when the spectrum is very blue, dereddening leads to changes in the blue flux that cannot be reproduced by altering the "temperature" of the emitted radiation. These results are extremely encouraging since they imply that detailed modeling of early spectra can shed light on both the abundances and total extinction of SNe II, the latter improving their utility and reliability as distance indicators. C1 Univ Oklahoma, Dept Phys & Astron, Norman, OK 73019 USA. Univ Georgia, Dept Phys & Astron, Athens, GA 30602 USA. Univ Georgia, Ctr Simulat Phys, Athens, GA 30602 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. Stockholm Observ, SE-13336 Saltsjobaden, Sweden. Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 USA. European So Observ, D-85748 Garching, Germany. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Carnegie Inst Washington, Las Campanas Observ, La Serena, Chile. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Australian Natl Univ, Mt Stromlo Observ, Weston, ACT 2611, Australia. NOAA, Cerro Tololo Interamer Observ, La Serena, Chile. Univ Texas, Dept Astron, Austin, TX 78712 USA. RP Baron, E (reprint author), Univ Oklahoma, Dept Phys & Astron, Norman, OK 73019 USA. RI Baron, Edward/A-9041-2009; Sonneborn, George/D-5255-2012; OI Baron, Edward/0000-0001-5393-1608; Schmidt, Brian/0000-0001-6589-1287 NR 22 TC 92 Z9 93 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP 444 EP 448 DI 10.1086/317795 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300043 ER PT J AU Davis, SS Sheehan, DP Cuzzi, JN AF Davis, SS Sheehan, DP Cuzzi, JN TI On the persistence of small regions of vorticity in the protoplanetary nebula SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; hydrodynamics; waves ID DISKS; WAVES; FLOW AB The fate of small regions of vorticity in a barotropic model of the protoplanetary nebula is investigated over thousands of years using a finite difference model. It is found that the coherence time for a small island of vorticity depends on its size, strength, orientation, and radial location in the nebula. Anticyclonic vorticity retains its coherence for longer times than cyclonic vorticity due to favorable interactions with the Keplerian shear flow. Rossby waves are generated as a result of mean vorticity gradients across the disk. The two-dimensional nebula evolves from discrete vortices into an axisymmetric flow consisting of small-amplitude vortex sheets at the radial locations of the initial vorticity. These vortex sheets induce an additional small, potential flow velocity superimposed on the Keplerian rotation curve. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ San Diego, Dept Phys, San Diego, CA 92110 USA. RP Davis, SS (reprint author), NASA, Ames Res Ctr, MS 260-1, Moffett Field, CA 94035 USA. EM sdavis@mail.arc.nasa.gov; dsheehan@acusd.edu; jcuzzi@mail.arc.nasa.gov NR 22 TC 11 Z9 11 U1 0 U2 1 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 DEC 10 PY 2000 VL 545 IS 1 BP 494 EP 503 DI 10.1086/317771 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300047 ER PT J AU Delannee, C AF Delannee, C TI Another view of the EIT wave phenomenon SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : flares; Sun : magnetic delds ID QUASI-SEPARATRIX LAYERS; CORONAL MASS EJECTIONS; MAGNETIC CONFIGURATIONS; SOHO/EIT OBSERVATIONS; SOLAR-FLARES; MODEL; RECONNECTION AB This paper investigates three different EIT waves. The events occurred on 1997 November 3 at 10: 31 UT, on 1998 January 27 at 22:19 UT, and on 1998 June 13 at 15:23 UT and were observed with EIT on board the Solar and Heliospheric Observatory (SOHO) using the 195 Angstrom filter that contains an Fe XII line. The three events show the following similar structures : 1. A flare in an active region. 2. A bright front that can lie at the same location for several hours. 3. A first dimming located between the bright front and the flare. 4. A second dimming located between the bright front and a magnetic dipole located in the opposite hemisphere. 5. A third dimming located in an active region located in the opposite hemisphere. 6. Brightenings or dimmings of transequatorial loops that connect the flaring active region to an active region located in the opposite hemisphere. We propose that the appearance of the above features is strongly related to magnetic field topology. Most of the EIT waves are associated with a coronal mass ejection (CME). Moreover, the presence of a flare is not a necessary condition to produce an EIT wave since only eruptive flares that are associated with CMEs are associated with a wave. Therefore, we suggest that the EIT-wave phenomenon is more closely related to the magnetic field evolution involved in CMEs than to wave propagation driven by solar flares. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Delannee, C (reprint author), NASA, Goddard Space Flight Ctr, Mail Code 682-3, Greenbelt, MD 20771 USA. NR 29 TC 111 Z9 114 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP 512 EP 523 DI 10.1086/317777 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300049 ER PT J AU Wilson, RM AF Wilson, RM TI Correlative aspects of the solar electron neutrino flux and solar activity SO ASTROPHYSICAL JOURNAL LA English DT Article DE elementary particles; Sun : activity; Sun : interior; Sun : particle emission ID SUNSPOT NUMBER; COSMIC-RAYS; CAPTURE RATE; ACTIVITY CYCLE; GEOMAGNETIC-ACTIVITY; STATISTICAL-ANALYSIS; TOTAL IRRADIANCE; TIME VARIATIONS; MAGNETIC-FIELD; MODULATION AB Between 1970 and 1994, the Homestake Solar Neutrino Detector obtained 108 observations of the solar electron neutrino flux (greater than 0.814 MeV). The "best fit" values derived from these observations suggest an average daily production rate of about 0.485 Ar-37 atom per day, a rate equivalent to about 2.6 SNU (solar neutrino units) or about a factor of 3 below the expected rate from the standard solar model. In order to explain, at least, a portion of this discrepancy, many researchers have speculated that the flux of solar neutrinos is variable, possibly being correlated with certain markers of the solar cycle (specifically, sunspot number and the Ap index). Indeed, previous studies, on the basis of shorter time intervals or data averaged in particular ways, often found evidence supportive for preferential behavior between the solar neutrino flux and solar activity. In this paper, using the larger "standard data set" and run-length-adjusted averages, the notion of preferential behavior between solar electron neutrino flux and solar activity is reexamined. The results clearly show that no statistically meaningful associations exist between the solar electron neutrino flux and any of the usual markers of solar activity, including sunspot number, the Ap index, the Deep River neutron monitor counts (cosmic rays), solar irradiance, and the number or size of solar energetic events (flares). C1 NASA, George C Marshall Space Flight Ctr, Sci Directorate, Huntsville, AL 35812 USA. RP Wilson, RM (reprint author), NASA, George C Marshall Space Flight Ctr, Sci Directorate, SD50, Huntsville, AL 35812 USA. NR 100 TC 7 Z9 7 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP 532 EP 546 DI 10.1086/317787 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385RW UT WOS:000166018300051 ER PT J AU Balbi, A Ade, P Bock, J Borrill, J Boscaleri, A De Bernardis, P Ferreira, PG Hanany, S Hristov, V Jaffe, AH Lee, AT Oh, S Pascale, E Rabii, B Richards, RL Smoot, GF Stompor, R Winant, CD Wu, JHP AF Balbi, A Ade, P Bock, J Borrill, J Boscaleri, A De Bernardis, P Ferreira, PG Hanany, S Hristov, V Jaffe, AH Lee, AT Oh, S Pascale, E Rabii, B Richards, RL Smoot, GF Stompor, R Winant, CD Wu, JHP TI Constraints on cosmological parameters from MAXIMA-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations; large-scale structure of universe ID MICROWAVE BACKGROUND ANISOTROPIES; POWER SPECTRUM; DARK-MATTER; CONSTANT; SUPERNOVAE; UNIVERSE AB We set new constraints on a seven-dimensional space of cosmological parameters within the class of inflationary adiabatic models. We use the angular power spectrum of the cosmic microwave background measured over a wide range of l in the first flight of the MAXIMA balloon-borne experiment (MAXIMA-1) and the low-l results from the COBE Differential Microwave Radiometer experiment. We find constraints on the total energy density of the universe, Omega = 1.0(-0.30)(+0.15), the physical density of baryons, Omega (b)h(2) = 0.03 +/- 0.01, the physical density of cold dark matter, Omega (cdm)h(2) = 0.2(-0.1)(+0.2), and the spectral index of primordial scalar fluctuations, n(s) = 1.08 +/- 0.1, all at the 95% confidence level. By combining our results with measurements of high-redshift supernovae we constrain the value of the cosmological constant and the fractional amount of pressureless matter in the universe to 0.45 < (Lambda) < 0.75 and 0.25 < Omega (m) < 0.50, at the 95% confidence level. Our results are consistent with a hat universe and the shape parameter deduced from large-scale structure, and in marginal agreement with the baryon density from big bang nucleosynthesis. C1 Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy. Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Natl Energy Res Sci Comp Ctr, Berkeley, CA 94720 USA. Univ London Queen Mary & Westfield Coll, London E1 4NS, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. CNR, IROE, Florence, Italy. Univ Rome La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. Univ Oxford, Dept Phys Astrophys Nucl & Astrophys, Oxford OX1 3RH, England. Inst Super Tecn, CENTRA, P-1094001 Lisbon, Portugal. Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Nicholas Copernicus Astron Ctr, PL-00716 Warsaw, Poland. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. RP Balbi, A (reprint author), Univ Roma Tor Vergata, Dipartimento Fis, Via Ric Sci 1, I-00133 Rome, Italy. RI Jaffe, Andrew/D-3526-2009 NR 28 TC 324 Z9 327 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP L1 EP L4 DI 10.1086/317323 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 388MP UT WOS:000166185100001 ER PT J AU Crenshaw, DM Kraemer, SB Hutchings, JB Danks, AC Gull, TR Kaiser, ME Nelson, CH Weistrop, D AF Crenshaw, DM Kraemer, SB Hutchings, JB Danks, AC Gull, TR Kaiser, ME Nelson, CH Weistrop, D TI Space Telescope Imaging Spectrograph echelle observations of NGC 4151: Variable ionization of the intrinsic UV absorbers SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 4151); galaxies : Seyfert ID SHORT-TIMESCALE VARIABILITY; ULTRAVIOLET-SPECTRUM; MULTIWAVELENGTH OBSERVATIONS; ABSORPTION-LINE; EMISSION-LINE; NGC-4151; OBJECTS; NGC4151; NARROW; IUE AB We present echelle observations of the intrinsic UV absorption lines in the Seyfert galaxy NGC 4151; these observations were obtained with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope on 1999 July 19. The UV-continuum flux at 1450 Angstrom decreased by factor of about 4 over the previous 2 years, and there was a corresponding dramatic increase in the column densities of the low-ionization absorption lines (e.g., Si II, Fe II, and Al II), presumably as a result of a decrease in the ionizing continuum. In addition to the absorption lines seen in previous low states, we identify a large number of Fe II absorption lines that arise from metastable levels as high as 4.1 eV above the ground state, indicating high densities (>10(6) cm(-3)). We find that the transient absorption feature in the blue wing of the broad C IV emission, seen in a Goddard High Resolution Spectrograph spectrum and thought to be a high-velocity C IV component, is actually a Si II fine-structure absorption line at a radial velocity of -560 km s(-1) (relative to systemic). We also demonstrate that the "satellite" emission lines of C IV found in IUE spectra are actually regions of unabsorbed continuum plus broad emission that become prominent when the UV continuum of NGC 4151 is in a low state. C1 Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Res Council Canada, Dominion Astrophys Observ, Victoria, BC V8X 4M6, Canada. NASA, Goddard Space Flight Ctr, Raytheon Polar Serv, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Univ Nevada, Dept Phys, Las Vegas, NV 89154 USA. RP Crenshaw, DM (reprint author), Catholic Univ Amer, Dept Phys, 200 Hannan Hall, Washington, DC 20064 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 27 TC 27 Z9 28 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP L27 EP L30 DI 10.1086/317333 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 388MP UT WOS:000166185100007 ER PT J AU Hanany, S Ade, P Balbi, A Bock, J Borrill, J Boscaleri, A De Bernardis, P Ferreira, PG Hristov, VV Jaffe, AH Lange, AE Lee, AT Mauskopf, PD Netterfield, CB Oh, S Pascale, E Rabii, B Richards, PL Smoot, GF Stompor, R Winant, CD Wu, JHP AF Hanany, S Ade, P Balbi, A Bock, J Borrill, J Boscaleri, A De Bernardis, P Ferreira, PG Hristov, VV Jaffe, AH Lange, AE Lee, AT Mauskopf, PD Netterfield, CB Oh, S Pascale, E Rabii, B Richards, PL Smoot, GF Stompor, R Winant, CD Wu, JHP TI MAXIMA-1: A measurement of the cosmic microwave background anisotropy on angular scales of 10 '-5 degrees SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations ID EMISSION; MAPS AB We present a map and an angular power spectrum of the anisotropy of the cosmic microwave background (CMB) from the first flight of the Millimeter-wave Anisotropy Experiment Imaging Array (MAXIMA). MAXIMA is a balloon-borne experiment with an array of 16 bolometric photometers operated at 100 mK. MAXIMA observed a 124 deg(2) region of the sky with 10' resolution at frequencies of 150, 240, and 410 GHz. The data were calibrated using in-flight measurements of the CMB dipole anisotropy. A map of the CMB anisotropy was produced from three 150 and one 240 GHz photometer without need for foreground subtractions. Analysis of this CMB map yields a power spectrum for the CMB anisotropy over the range 36 less than or equal to l less than or equal to 785. The spectrum shows a peak with an amplitude of 78 +/- 6 muK at l similar or equal to 220 and an amplitude varying between similar to 40 and similar to 50 muK for 400 less than or similar to l less than or similar to 785. C1 Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA. Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. Univ London Queen Mary & Westfield Coll, London E1 4NS, England. Univ Roma Tor Vergata, Dipartimento Fis, I-00133 Rome, Italy. Lawrence Berkeley Natl Lab, Div Phys, Berkeley, CA 94720 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Dept Phys, Pasadena, CA 91125 USA. Lawrence Berkeley Natl Lab, Natl Energy Res Sci Comp Ctr, Berkeley, CA 94720 USA. CNR, IROE, I-50127 Florence, Italy. Univ Rome La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. Univ Oxford, Dept Astrophys, Oxford OX1 3RH, England. Inst Super Tecn, CENTRA, Lisbon, Portugal. Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA. Univ Wales, Dept Phys & Astron, Cardiff CF2 3YB, S Glam, Wales. Univ Toronto, Dept Phys & Astron, Toronto, ON M5S 1A1, Canada. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Copernicus Astron Ctr, PL-00716 Warsaw, Poland. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. RP Hanany, S (reprint author), Univ Minnesota, Sch Phys & Astron, 116 Church St SE, Minneapolis, MN 55455 USA. RI Jaffe, Andrew/D-3526-2009 NR 28 TC 756 Z9 762 U1 4 U2 11 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP L5 EP L9 DI 10.1086/317322 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 388MP UT WOS:000166185100002 ER PT J AU Sekanina, Z AF Sekanina, Z TI Solar and Heliospheric observatory sungrazing comets with prominent tails: Evidence on dust-production peculiarities SO ASTROPHYSICAL JOURNAL LA English DT Article DE comets : general; methods : data analysis AB A preliminary examination of the tails of 11 Solar and Heliospheric Observatory (SOHO) sungrazers, observed between 3 and 20 R. on their approach to the Sun, provides information on dust ejected from these comets and on the forces to which the microscopic grains are subjected. Images taken at times of the SOHO spacecraft's transit across the orbit planes of sungrazers show their tails to be perfectly straight and extremely narrow and their apparent position coinciding with that of the projected orbit plane. This result suggests relatively low particle-ejection velocities in the direction normal to the orbit plane (estimated at less than similar to 100 m s(-1)) and offers no evidence whatsoever for the Lorentz force on charged dust. When viewed broadside, the sungrazers' tails are always narrow, either straight or slightly curved, and deviating strikingly from the antisolar direction, an indication that no microscopic dust was ejected during a period of time just preceding observation. The tails include a major population of submicron-sized grains that are dielectric in nature, most probably silicates, since the radiation-pressure accelerations are found never to exceed 0.6 of the solar attraction. The sampled comets show rather consistently that the production of this dust terminated at similar to 20-30 R. from the Sun along the inbound orbit. The tail of one of the brightest SOHO sungrazers is modeled in slightly greater detail, including its curvature, which abruptly increases at a point approximately halfway between the head and the far end. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sekanina, Z (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 10 PY 2000 VL 545 IS 1 BP L69 EP L72 DI 10.1086/317336 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 388MP UT WOS:000166185100017 ER PT J AU Hixon, R AF Hixon, R TI Prefactored small-stencil compact schemes SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE compact differencing; high-order finite differences; computational aeroacoustics ID FINITE-DIFFERENCE SCHEMES; DEPENDENT BOUNDARY-CONDITIONS; HYPERBOLIC SYSTEMS; COMPUTATIONAL ACOUSTICS; RUNGE-KUTTA; RESOLUTION; FLOWS AB A new type of prefactored compact schemes is presented that obtains high-order accuracy while using a very small stencil size. These schemes require fewer boundary stencils and offer simpler boundary condition implementation than the existing compact schemes. Results are shown for linear and nonlinear I-D benchmark problems and a 2-D linear benchmark problem. Boundary stencils for both exterior and interior multiblock boundaries are given, and boundary condition specification is described and demonstrated, (C) 2000 Academic Press. C1 NASA, Glenn Res Ctr, Inst Computat Mech Propuls, Cleveland, OH 44135 USA. RP Hixon, R (reprint author), NASA, Glenn Res Ctr, Inst Computat Mech Propuls, Cleveland, OH 44135 USA. NR 26 TC 46 Z9 53 U1 0 U2 4 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD DEC 10 PY 2000 VL 165 IS 2 BP 522 EP 541 DI 10.1006/jcph.2000.6631 PG 20 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 393ZY UT WOS:000166500600010 ER PT J AU Condie, KC Des Marais, DJ Abbott, D AF Condie, Kent C. Des Marais, David J. Abbott, Dallas TI Geologic evidence for a mantle superplume event at 1.9 Ga SO GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS LA English DT Article DE Mantle plumes; sea level; superplume; carbon isotopes; black shales AB Both preserved and restored areal distributions of Proterozoic marine intracratonic,passive margin, and platform sediments show a prominent peak at similar to 1.9 Ga, indicating that shallow marine sediments were widespread on the continents and that sea level was high at this time. The chemical index of alteration in shales deposited at this time was high, suggesting warm climates, possibly due to enhanced CO2 levels in the atmosphere. High sea level and warms climates may also explain an abundance of black shale, banded iron formations, and shallow marine phosphate deposits and an increase in the number of occurrences and diversity of stromatolites in general and microdigitate stromatolites at 1.9 Ga. All of these observations are consistent with a 1.9-Ga superplume event. The occurrence of only a minor positive carbon isotope shift in marine carbonates at 1.9 Ga indicates that the relative rates of burial of organic and oxidized carbon remained about the same as at present. Slightly low Sr-87/Sr-86 isotopic ratios in seawater at 1.9 Ga reflect increased mantle input of Sr from the proposed superplume event, whereas higher ratios at 1.85-1.75 Ga may reflect increased input of continental Sr from a growing supercontinent. The first massive sulfate evaporites in the geologic record at 1.8-1.6 Ga follow the possible 1.9-Ga superplume event. This may reflect an increase in both oxidation state and carbonate deposition in the oceans as plume-related volcanism wanes. C1 [Condie, Kent C.] New Mexico Inst Min & Technol, Dept Earth & Environm Sci, Socorro, NM 87801 USA. [Des Marais, David J.] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. [Abbott, Dallas] Lamont Doherty Earth Observ, Palisades, NY 10964 USA. RP Condie, KC (reprint author), New Mexico Inst Min & Technol, Dept Earth & Environm Sci, Socorro, NM 87801 USA. EM kcondie@nmt.edu; ddesmarais@mail.arc.nasa.gov; dallas@ldeo.columbia.edu NR 157 TC 0 Z9 0 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 1525-2027 J9 GEOCHEM GEOPHY GEOSY JI Geochem. Geophys. Geosyst. PD DEC 5 PY 2000 VL 1 PG 25 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA V22KH UT WOS:000208273600001 ER PT J AU Smith, GD Ciszak, E Magrum, LA Pangborn, WA Blessing, RH AF Smith, GD Ciszak, E Magrum, LA Pangborn, WA Blessing, RH TI R-6 hexameric insulin complexed with m-cresol or resorcinol SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Article ID HALF-SITE REACTIVITY; ALLOSTERIC TRANSITION; STRUCTURE REFINEMENT; MAXIMUM-LIKELIHOOD; MUTANT INSULINS; PHENOL; BINDING; ZINC; CRYSTALLOGRAPHY; SYSTEM AB The structures of three R-6 human insulin hexamers have been determined. Crystals of monoclinic m-cresol-insulin, monoclinic resorcinol-insulin and rhombohedral m-cresol-insulin diffracted to 1.9, 1.9 and 1.78 Angstrom, respectively, and have been refined to residuals of 0.195, 0.179 and 0.200, respectively. In all three structures, a phenolic derivative is found to occupy the phenolic binding site, where it forms hydrogen bonds to the carbonyl O atom of CysA6 and the N atom of CysA11. Two additional phenolic derivative binding sites were identified within or between hexamers. The structures of all three hexamers are nearly identical, although a large displacement of the N-terminus of one B chain in both monoclinic structures results from coordination to a sodium ion which is located between symmetry-related hexamers. Other minor differences in structure arise from differences in packing in the monoclinic cell compared with the rhombohedral cell. Based upon the differences in conformation of the GluB13 side chains in T-6, T3R3f and R-6 hexamers, the deprotonation of these side chains appears to be associated with the T --> R conformational transition. C1 Hauptman Woodward Med Res Inst, Buffalo, NY 14203 USA. New York State Dept Hlth, Roswell Pk Canc Inst, Buffalo, NY 14263 USA. RP Smith, GD (reprint author), NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Struct Biol Lab, Huntsville, AL 35812 USA. FU NIGMS NIH HHS [GM56829] NR 34 TC 42 Z9 43 U1 1 U2 10 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0907-4449 J9 ACTA CRYSTALLOGR D JI Acta Crystallogr. Sect. D-Biol. Crystallogr. PD DEC PY 2000 VL 56 BP 1541 EP 1548 DI 10.1107/S0907444900012749 PN 12 PG 8 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA 377HX UT WOS:000165509100003 PM 11092919 ER PT J AU Sayir, A Farmer, SC AF Sayir, A Farmer, SC TI The effect of the microstructure on mechanical properties of directionally solidified Al(2)O(3)/ZrO(2)(Y(2)O(3)) eutectic SO ACTA MATERIALIA LA English DT Article; Proceedings Paper CT Acta Materialia Workshop on Ceramic and Biomaterial Interfaces: Designing for Properties CY SEP 20-23, 1999 CL SEVILLE, SPAIN SP Spanish Natl Res Council, Minist Educ, Minist Ind, Univ Seville, Acta Materialia Inc, European Off Aerosp Res & Dev, USAF, Off Sci Res, USAF, Res Lab, USA, Res & Dev & Standardizat Grp, US Off Naval Res Europe, Lawrence Berkeley Natl Lab DE ceramic; solidification; creep; high temperature ID SINGLE-CRYSTALS; CRYSTALLOGRAPHY; CREEP AB The eutectic architecture of a continuous reinforcing phase within a higher volume fraction phase or matrix, can be described as a naturally occurring in-situ composite. Here we report the results of experiments aimed at identifying the sources of high temperature creep resistance and high levels of strength in a two phase Al(2)O(3)/ZrO(2)(Y(2)O(3)) system. The mechanical properties of two phase Al(2)O(3)/ZrO(2)(Y(2)O(3)) eutectic are superior to that of either constituent alone due to strong constraining effects provided by the coherent interfaces and microstructure. The Al(2)O(3)/ZrO(2)(Y(2)O(3)) eutectic maintains a low energy interface resulting from directional solidification and can produce strong and stable reinforcing phase/matrix bonding. The phases comprising a eutectic are thermodynamically compatible at higher homologous temperatures than man-made composites and as such offer the potential for superior high temperature properties. (C) 2000 Acta Metallurgica Inc, Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Sayir, A (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd, Cleveland, OH 44135 USA. EM Ali.sayir@lerc.nasa.gov NR 20 TC 122 Z9 139 U1 1 U2 28 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1359-6454 J9 ACTA MATER JI Acta Mater. PD DEC 1 PY 2000 VL 48 IS 18-19 BP 4691 EP 4697 DI 10.1016/S1359-6454(00)00259-7 PG 7 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA 381DL UT WOS:000165747000038 ER PT J AU Salama, M Kuo, CP Lou, M AF Salama, M Kuo, CP Lou, M TI Simulation of deployment dynamics of inflatable structures SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA/ASME/ASCE/AHS/ASC 40th Structures, Structural Dynamics, and Materials Conference CY APR 12-15, 1999 CL ST LOUIS, MISSOURI SP Amer Inst Aeronaut & Astronaut, ASME, ASCE, AHS, ASC AB Analytical simulation of the inflation process of inflatable structures is key to assessing their robust deployment in a space environment. Although the problem seems to be intractable, a simplified finite volume inflation model is developed, which allows discretized description of the gas flow, pressure variation, and resulting nonlinear large deformation throughout domains of the inflatable structure. Simulation results are presented along with convergence studies, which provide insight into the deployment of three different packaging/deployment schemes: Z-unfolding, rollout, and extrusion of a cylindrical tube. The proposed inflation model is not limited to prismatic one-dimensional components and can be applied to inflatable shapes with complex configurations. As a validation of the numerical simulation, a laboratory experiment was conducted on the Z-folded configuration. Generally, good agreement in the overall inflation dynamics is observed between the analysis and experiment. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Salama, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 9 Z9 10 U1 1 U2 10 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD DEC PY 2000 VL 38 IS 12 BP 2277 EP 2283 PG 7 WC Engineering, Aerospace SC Engineering GA 378CY UT WOS:000165568500010 ER PT J AU Foster, PP Feiveson, AH Glowinski, R Izygon, M Boriek, AM AF Foster, PP Feiveson, AH Glowinski, R Izygon, M Boriek, AM TI A model for influence of exercise on formation and growth of tissue bubbles during altitude decompression SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE macro- and microsystem; O-2 serial transport; O-2 tissue uptake; O-2 window; N-2 supersaturation; Poisson process ID VENOUS GAS EMBOLI; BLOOD-FLOW; BIOLOGICAL-FLUIDS; SICKNESS; OXYGEN; CONSUMPTION; SIMULATION; PREDICTION; SOLUBILITY; EVOLUTION AB In response to exercise performed before or after altitude decompression, physiological changes are suspected to affect the formation and growth of decompression bubbles. We hypothesized that the work to change the size of a bubble is done by gas pressure gradients in a macro- and microsystem of thermodynamic forces and that the number of bubbles formed through time follows a Poisson process. We modeled the influence of tissue O-2 consumption on bubble dynamics in the O-2 transport system in series against resistances, from the alveolus to the microsystem containing the bubble and its surrounding tissue shell. Realistic simulations of experimental decompression procedures typical of actual extravehicular activities were obtained. Results suggest that exercise-induced elevation of O-2 consumption at altitude leads to bubble persistence in tissues. At the same time, exercise-enhanced perfusion leads to an overall suppression of bubble growth. The total volume of bubbles would be reduced unless increased tissue motion simultaneously raises the rate of bubble formation through cavitation processes, thus maintaining or increasing total bubble volume, despite the exercise. C1 Baylor Coll Med, Dept Med, Pulm & Crit Care Sect, Houston, TX 77030 USA. NASA, Div Med Sci, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Houston, Div Math, Houston, TX 77004 USA. Univ Houston, Dept Phys, Houston, TX 77004 USA. RP Foster, PP (reprint author), Baylor Coll Med, Dept Med, Pulm & Crit Care Sect, 6550 Fannin St,Smith Tower,Suite 1225, Houston, TX 77030 USA. NR 51 TC 9 Z9 9 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0363-6119 J9 AM J PHYSIOL-REG I JI Am. J. Physiol.-Regul. Integr. Comp. Physiol. PD DEC PY 2000 VL 279 IS 6 BP R2304 EP R2316 PG 13 WC Physiology SC Physiology GA 374LV UT WOS:000165347400043 PM 11080099 ER PT J AU Foster, PP Feiveson, AH Boriek, AM AF Foster, PP Feiveson, AH Boriek, AM TI Predicting time to decompression illness during exercise at altitude, based on formation and growth of bubbles SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE time-varying volume of bubbles; cumulative volume of bubbles; rate of bubble formation; instantaneous probability of pain; susceptibility to decompression illness; Cox-Snell residuals ID VENOUS GAS EMBOLI; PROBABILISTIC MODEL; SICKNESS; LIKELIHOOD; DIVES; AIR AB For altitude decompressions, we hypothesized that reported onset times of limb decompression illness (DCI) pain symptoms follow a probability distribution related to total bubble volume [V-b. (t)] as a function of time. Furthermore, we hypothesized that the probability of ever experiencing DCI during a decompression is associated with the cumulative volume of bubbles formed. To test these hypotheses, we first used our previously developed formation-and-growth model (Am J Physiol Regulatory Integrative Comp Physiol 279: R2304-R2316, 2000) to simulate Vb.( t) for 20 decompression profiles in which 334 human subjects performed moderate repetitive skeletal muscle exercise (827 kJ/h) in an altitude chamber. Using survival analysis, we determined that, for a controlled condition of exercise, the fraction of the subject population susceptible to DCI can be approximately expressed as a power function of the formation-and-growth model-predicted cumulative volume of bubbles throughout the altitude exposure. Furthermore, for this fraction, the probability density distribution of DCI onset times is approximately equal to the ratio of the time course of formation-and growth-modeled total bubble volume to the predicted cumulative volume. C1 Baylor Coll Med, Dept Med, Pulm & Crit Care Sect, Houston, TX 77030 USA. NASA, Div Med Sci, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Foster, PP (reprint author), Baylor Coll Med, Dept Med, Pulm & Crit Care Sect, 6550 Fannin St,Smith Tower,Suite 1225, Houston, TX 77030 USA. NR 36 TC 5 Z9 5 U1 1 U2 2 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0363-6119 J9 AM J PHYSIOL-REG I JI Am. J. Physiol.-Regul. Integr. Comp. Physiol. PD DEC PY 2000 VL 279 IS 6 BP R2317 EP R2328 PG 12 WC Physiology SC Physiology GA 374LV UT WOS:000165347400044 PM 11080100 ER PT J AU Biswas, R Das, SK Harvey, DJ Oliker, L AF Biswas, R Das, SK Harvey, DJ Oliker, L TI Parallel dynamic load balancing strategies for adaptive irregular applications SO APPLIED MATHEMATICAL MODELLING LA English DT Article DE unstructured mesh adaptation; global dynamic load balancing; symmetric broadcast networks; parallel computing ID UNSTRUCTURED MESHES; COMPUTERS AB Dynamic unstructured mesh adaptation is a powerful technique for solving computational problems with evolving physical features; however, an efficient parallel implementation is rather difficult because of the load imbalance that mesh adaptation creates. To address this problem, we have developed two dynamic load balancing strategies for parallel adaptive irregular applications. The first, called PLUM, is an architecture-independent framework particularly geared toward adaptive numerical computations and requires that all data be globally redistributed after each adaptation to achieve load balance. The second is a more general-purpose topology-independent load balancer that utilizes symmetric broadcast networks (SBN) as the underlying communication pattern, with a goal to providing a global view of system loads across processors. Results indicate that both PLUM and the SBN-based approach have their relative merits, and that they achieve excellent load balance at the cost of minimal extra overhead. (C) 2000 Elsevier Science Inc. All rights reserved. C1 NASA, Ames Res Ctr, Comp Sci Corp, Moffett Field, CA 94035 USA. Univ Texas, Dept Comp Sci & Engn, Arlington, TX 76019 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, NERSC, Berkeley, CA 94720 USA. RP Biswas, R (reprint author), NASA, Ames Res Ctr, Comp Sci Corp, Mail Stop T27 A-1, Moffett Field, CA 94035 USA. EM rbiswas@nas.nasa.gov; das@cse.uta.edu; harvey@cse.uta.edu; loliker@lbl.gov NR 30 TC 3 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0307-904X EI 1872-8480 J9 APPL MATH MODEL JI Appl. Math. Model. PD DEC PY 2000 VL 25 IS 2 BP 109 EP 122 DI 10.1016/S0307-904X(00)00040-8 PG 14 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications; Mechanics SC Engineering; Mathematics; Mechanics GA 390PZ UT WOS:000166306700004 ER PT J AU Parkinson, CL AF Parkinson, CL TI Variability of Arctic sea ice: The view from space, an 18-year record SO ARCTIC LA English DT Article; Proceedings Paper CT Conference on Arctic Seas - Currents of Change CY OCT 21-24, 1998 CL MYSTIC, CT DE Arctic sea ice; climate change; polar climate; remote sensing ID SYNTHETIC-APERTURE-RADAR; NORTH-ATLANTIC OSCILLATION; AIR-TEMPERATURE; RADIOMETER DATA; MICROWAVE DATA; POLAR-REGIONS; IMAGERY; SURFACE; TRENDS; MOTION AB A recently compiled 18-year record ( 1979 to 1996) of sea ice concentrations derived from four passive-microwave satellite instruments has allowed the quantification of a variety of measures of Arctic sea ice variability. Earlier maps generated using data through August 1987 have been updated to 18-year summaries of the annual range of sea ice distributions, the interannual variability of average monthly sea ice distributions, the frequency of sea ice coverage over the 18-years, the length of the sea ice season, and trends in the length of the sea ice season. Linear least squares trends over the 18-year record show the sea ice season to have lengthened over some sizeable regions, especially in the Bering Sea, Baffin Bay, Davis Strait, the Labrador Sea, and the Gulf of St. Lawrence, but to have shortened over a much larger area, including the Sea of Okhotsk, the Greenland Sea, the Barents Sea, and all the seas along the north coast of Russia. The area with trends showing sea ice seasons shortening by over 0.5 days/year is 7.5 x 10(6) km(2), over 2.5 times the area experiencing a lengthening of the sea ice season by over 0.5 days/year. Neither the shortening nor the lengthening, however, is uniform or monotonic over the 18-year record. Instead, the ice cover exhibits widespread interannual variability, not just in the length of the sea ice season but for each month-a fact well illustrated by the monthly average September ice coverage, which was at its lowest extent in 1995 but at its second highest one year later, in the final year of the record. The maps of ice frequency and ice variability can help identify how anomalous individual years are. In some cases, they can help forestall unnecessary concern over seemingly unusual conditions which, upon examination of the maps, are found to fall well within the observed variability. C1 NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Greenbelt, MD 20771 USA. RP Parkinson, CL (reprint author), NASA, Goddard Space Flight Ctr, Oceans & Ice Branch, Code 971, Greenbelt, MD 20771 USA. EM clairep@neptune.gsfc.nasa.gov RI Parkinson, Claire/E-1747-2012 OI Parkinson, Claire/0000-0001-6730-4197 NR 76 TC 65 Z9 69 U1 2 U2 13 PU ARCTIC INST N AMER PI CALGARY PA UNIV OF CALGARY 2500 UNIVERSITY DRIVE NW 11TH FLOOR LIBRARY TOWER, CALGARY, ALBERTA T2N 1N4, CANADA SN 0004-0843 J9 ARCTIC JI Arctic PD DEC PY 2000 VL 53 IS 4 BP 341 EP 358 PG 18 WC Environmental Sciences; Geography, Physical SC Environmental Sciences & Ecology; Physical Geography GA 388UP UT WOS:000166201700002 ER PT J AU Williams, RE Baum, S Bergeron, LE Bernstein, N Blacker, BS Boyle, BJ Brown, TM Carollo, CM Casertano, S Covarrubias, R de Mello, DF Dickinson, ME Espey, BR Ferguson, HC Fruchter, A Gardner, JP Gonnella, A Hayes, J Hewett, PC Heyer, I Hook, R Irwin, M Jones, D Kaiser, ME Levay, Z Lubenow, A Lucas, RA Mack, J MacKenty, JW Madau, P Makidon, RB Martin, CL Mazzuca, L Mutchler, M Norris, RP Perriello, B Phillips, MM Postman, M Royle, P Sahu, K Savaglio, S Sherwin, A Smith, TE Stiavelli, M Suntzeff, NB Teplitz, HI van der Marel, RP Walker, AR Weymann, RJ Wiggs, MS Williger, GM Wilson, J Zacharias, N AF Williams, RE Baum, S Bergeron, LE Bernstein, N Blacker, BS Boyle, BJ Brown, TM Carollo, CM Casertano, S Covarrubias, R de Mello, DF Dickinson, ME Espey, BR Ferguson, HC Fruchter, A Gardner, JP Gonnella, A Hayes, J Hewett, PC Heyer, I Hook, R Irwin, M Jones, D Kaiser, ME Levay, Z Lubenow, A Lucas, RA Mack, J MacKenty, JW Madau, P Makidon, RB Martin, CL Mazzuca, L Mutchler, M Norris, RP Perriello, B Phillips, MM Postman, M Royle, P Sahu, K Savaglio, S Sherwin, A Smith, TE Stiavelli, M Suntzeff, NB Teplitz, HI van der Marel, RP Walker, AR Weymann, RJ Wiggs, MS Williger, GM Wilson, J Zacharias, N TI The Hubble Deep Field south: Formulation of the observing campaign SO ASTRONOMICAL JOURNAL LA English DT Article DE catalogs; cosmology : observations; galaxies : evolution; galaxies : formation; galaxies : photometry; surveys ID STAR-FORMATION HISTORY; GALAXY PHOTOMETRY; SOURCE EXTRACTION; FORMING GALAXIES; RADIO-EMISSION; STANDARD STARS; DATA REDUCTION; EVOLUTION; REDSHIFTS; CALIBRATION AB Deep, multiband observations of high Galactic latitude fields are an essential tool for studying topics ranging from Galactic structure to extragalactic background radiation. The Hubble Deep Field (HDF-N) observations obtained in 1995 December established a standard for such narrow, deep surveys. The held has been extensively analyzed by a variety of groups and has been widely studied with imaging and spectroscopy over wavelengths ranging from 10(-3) to 2 x 10(5) mum. We describe here a second deep field campaign (HDF-S), this time in the southern hemisphere, undertaken by the Hubble Space Telescope (HST) in 1998 October in a program very similar to the northern Hubble Deep Field. Imaging and spectroscopy of three adjacent fields in the southern continuous viewing zone were obtained simultaneously for 150 orbits, and a mosaic of flanking fields was imaged for 27 additional orbits. Two important features of the HDF-S distinguish it from the HDF-N: the campaign included parallel observations by the three main HST instruments-WFPC2, STIS, and NICMOS-and the HDF-S location was selected to place a bright z = 2.24 quasar in the STIS field of view. The HDF-S observations consist of WVFPC2 images in filters close to U, B, y, and I, a deep STIS image of the held surrounding the quasar, spectroscopy of the quasar with STIS from 1150 to 3560 Angstrom and deep imaging of an adjacent field with NICMOS camera 3 at 1.1, 1.6, and 2.2 mum. All of the HDF-S data were fully reduced and made publicly available within 2 months of the observations, and we describe here the selection of the fields and the observing strategy that was employed. Detailed descriptions of the data and the reduction techniques for each field, together with the corresponding source catalogs, appear in separate papers. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Anglo Australian Observ, Epping, NSW 2121, Australia. Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Cerro Tololo Interamer Observ, La Serena, Chile. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. Space Telescope European Coordinating Facil, D-85748 Garching, Germany. Australia Telescope Natl Facil, Epping, NSW 2121, Australia. Carnegie Inst Washington Observ, Pasadena, CA 91109 USA. USN Observ, Washington, DC 20392 USA. RP Williams, RE (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. RI Norris, Ray/A-1316-2008; OI Norris, Ray/0000-0002-4597-1906; Espey, Brian/0000-0002-2457-1380 NR 48 TC 108 Z9 109 U1 1 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD DEC PY 2000 VL 120 IS 6 BP 2735 EP 2746 DI 10.1086/316854 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 383EU UT WOS:000165870800001 ER PT J AU Palunas, P Williams, TB AF Palunas, P Williams, TB TI Maximum disk mass models for spiral galaxies SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : fundamental parameters; galaxies : halos; galaxies : kinematics and dynamics galaxies : photometry; galaxies : spiral; galaxies : structure ID TULLY-FISHER RELATION; SURFACE BRIGHTNESS GALAXIES; OPTICAL-ROTATION CURVES; DARK-MATTER HALOS; BARRED GALAXIES; PECULIAR VELOCITIES; DYNAMICAL FRICTION; PATTERN SPEED; CLUSTER; EXTINCTION AB We present axisymmetric maximum disk mass models for a sample of 74 spiral galaxies taken from the southern sky Fabry-Perot Tully-Fisher survey by Schommer et al. The sample contains galaxies spanning a large range of morphologies and having rotation widths from 180 km s(-1) to 680 km s(-1) For each galaxy we have an I-band image and a two-dimensional H alpha velocity field. We decompose the disk and bulge by fitting models directly to the I-band image. This method utilizes both the distinct surface brightness profiles and shapes of the projected disk and bulge in the galaxy images. The luminosity profiles and rotation curves are derived using consistent centers, position angles, and inclinations derived from the photometry and velocity maps. The distribution of mass is modeled as a sum of disk and bulge components with distinct, constant mass-to-light ratios. No dark matter halo is included in the fits. The models reproduce the overall structure of the rotation curves in the majority of galaxies, providing good fits to galaxies that exhibit pronounced structural differences in their surface brightness profiles. Of galaxies for which the rotation curve is measured to R-23.5 or beyond 75% are well fitted by a mass-traces-light model for the entire region within R-23.5. The models for about 20% of the galaxies do not fit well; the failure of most of these models is traced directly to nonaxisymmetric structures, primarily bars but also strong spiral arms. The median I-band MIL of the disk plus bulge is 2.4 +/- 0.9 h(75) in solar units, consistent with normal stellar populations. These results require either that the mass of dark matter within the optical disk of spiral galaxies is small or that its distribution is very precisely coupled to the distribution of luminous matter. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Rutgers State Univ, Dept Phys & Astron, Piscataway, NJ 08855 USA. RP NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. EM palunas@gsfc.nasa.gov; williams@physics.rutgers.edu NR 71 TC 116 Z9 118 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD DEC PY 2000 VL 120 IS 6 BP 2884 EP 2903 DI 10.1086/316878 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 383EU UT WOS:000165870800010 ER PT J AU Bock, JJ Neugebauer, G Matthews, K Soifer, BT Becklin, EE Ressler, M Marsh, K Werner, MW Egami, E Blandford, R AF Bock, JJ Neugebauer, G Matthews, K Soifer, BT Becklin, EE Ressler, M Marsh, K Werner, MW Egami, E Blandford, R TI High spatial resolution imaging of NGC 1068 in the mid-infrared SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 1068); infrared radiation ID SUBARCSECOND RADIO STRUCTURE; ACTIVE GALACTIC NUCLEI; X-RAY; NGC-1068; EMISSION; GALAXIES; DUST; TORUS; GAS; LOCATION AB Mid-infrared observations of the central source of NGC 1068 have been obtained with a spatial resolution in the deconvolved image of 0."1 (similar to7 pc). The central source is extended by similar to1 " in the north-south direction but appears unresolved in the east-west direction over most of its length. About 2/3 of its flux can be ascribed to a core structure that is itself elongated north-south and does not show a distinct unresolved compact source. The source is strongly asymmetric, extending significantly farther to the north than to the south. The morphology of the mid-infrared emission appears similar to that of the radio jet and has features which correlate with the images in CO mi. Its 12.5-24.5 mum color temperature ranges from 215 to 260 K and does not decrease smoothly with distance from the core. Silicate absorption is strongest in the core and to the south and is small in the north. The core, apparently containing 2/3 of the bolometric luminosity of the inner 4 " diameter area, may be explained by a thick, dusty torus near the central active galactic nucleus (AGN) viewed at an angle of similar to 65 degrees to its plane. There are, however, detailed difficulties with existing models, especially the narrow east-west width of the thin extended mid-infrared "tongue" to the north of the core. We interpret the tongue as reprocessed visual and ultraviolet radiation that is strongly beamed and that originates in the AGN. C1 CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Palomar Observ, Pasadena, CA 91125 USA. CALTECH, SIRTF Sci Ctr, Pasadena, CA 91125 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, IPAC, Pasadena, CA 91125 USA. RP Bock, JJ (reprint author), CALTECH, Div Phys Math & Astron, Pasadena, CA 91125 USA. NR 60 TC 79 Z9 79 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD DEC PY 2000 VL 120 IS 6 BP 2904 EP 2919 DI 10.1086/316871 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 383EU UT WOS:000165870800011 ER PT J AU Strickland, DK Heckman, TM Weaver, KA Dahlem, M AF Strickland, DK Heckman, TM Weaver, KA Dahlem, M TI Chandra observations of NGC 253: New insights into the nature of starburst-driven superwinds SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 253); galaxies : starburst; ISM : jets and outflows; X-rays ID X-RAY-EMISSION; NGC 253; SPIRAL GALAXIES; M82; LUMINOSITY; MINISURVEY; RESOLUTION; SPECTRA; WINDS; GAS AB Arcsecond-resolution X-ray imaging of the nucleus of the nearby starburst galaxy NGC 253 with Chandra reveals a well-collimated, strongly limb-brightened, kiloparsec-scale conical outflow from the central starburst region. The outflow is very similar in morphology to the known H alpha outflow cone, on scales down to less than or similar to 20 pc. This provides, for the first time, robust evidence that both X-ray and H alpha emission come from low volume filling factor regions of interaction between the fast energetic wind of SN ejecta and the denser ambient interstellar medium and not from the wind fluid itself. We provide estimates of the (observationally and theoretically important) filling factor of the X-ray-emitting gas, of between similar to4% and 40%, consistent with an upper limit of similar to 40%, based directly on the observed limb-brightened morphology of the outflow. Only less than or similar to 20% of the observed X-ray emission can come from the volume-filling. metal-enriched, wind fluid itself. Spatially resolved spectroscopy of the soft diffuse thermal X-ray emission reveals that the predominant source of spectral variation along the outflow cones is due to strong variation in the absorption on scales of similar to 60 pc, there being little change in the characteristic temperature of the emission. We show that these observations are easily explained by, and fully consistent with, the standard model of a superwind driven by a starburst of the observed power of NGC 253. If these results are typical of all starburst-driven winds, then we do not directly see all the energy and gas tin particular the hot metal-enriched gas) transported out of galaxies by superwinds, even in X-ray emission. C1 Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. Sterrewacht Leiden, NL-2300 RA Leiden, Netherlands. RP Johns Hopkins Univ, Dept Phys & Astron, 3400 N Charles St, Baltimore, MD 21218 USA. EM dks@pha.jhu.edu; heckman@pha.jhu.edu; kweaver@cleo.gsfc.nasa.gov; mdahlem@strw.leidenuniv.nl NR 23 TC 139 Z9 139 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD DEC PY 2000 VL 120 IS 6 BP 2965 EP 2974 DI 10.1086/316846 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 383EU UT WOS:000165870800016 ER PT J AU Moehler, S Sweigart, AV Landsman, WB Heber, U AF Moehler, S Sweigart, AV Landsman, WB Heber, U TI Hot HB stars in globular custers - Physical parameters and consequences for theory V. Radiative levitation versus helium mixing (vol 360, pg 120, 2000) SO ASTRONOMY & ASTROPHYSICS LA English DT Correction C1 Univ Erlangen Nurnberg, Inst Astron, D-96049 Bamberg, Germany. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Moehler, S (reprint author), Univ Erlangen Nurnberg, Inst Astron, D-96049 Bamberg, Germany. EM moehler@sternwarte.uni-erlangen.de; sweigart@bach.gsfc.nasa.gov; landsman@mpb.gsfc.nasa.gov; heber@sternwarte.uni-erlangen.de RI Heber, Ulrich/G-3306-2013 OI Heber, Ulrich/0000-0001-7798-6769 NR 1 TC 0 Z9 0 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 DEC PY 2000 VL 364 IS 2 BP 926 EP 926 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 402PY UT WOS:000166998400072 ER PT J AU Andersen, MI Hjorth, J Pedersen, H Jensen, BL Hunt, LK Gorosabel, J Moller, P Fynbo, J Kippen, RM Thomsen, B Olsen, LF Christensen, L Vestergaard, M Masetti, N Palazzi, E Hurley, K Cline, T Kaper, L Jaunsen, AO AF Andersen, MI Hjorth, J Pedersen, H Jensen, BL Hunt, LK Gorosabel, J Moller, P Fynbo, J Kippen, RM Thomsen, B Olsen, LF Christensen, L Vestergaard, M Masetti, N Palazzi, E Hurley, K Cline, T Kaper, L Jaunsen, AO TI VLT identification of the optical afterglow of the gamma-ray burst GRB 000131 at z=4.50 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE cosmology : observations; gamma rays : bursts; ISM : dust, extinction ID 28 FEBRUARY 1997; STANDARD STARS; LIGHT CURVES; REDSHIFT; GRB-990510; DIVERSITY; DISCOVERY; EMISSION; SPECTRA; DUST AB We report the discovery of the gamma-ray burst GRB 000131 and its optical afterglow. The optical identification was made with the VLT 84 hours after the burst following a BATSE detection and an Inter Planetary Network localization. GRB 000131 was a bright, long-duration GRB, with an apparent precursor signal 62 s prior to trigger. The afterglow was detected in ESO VLT, NTT, and DK1.54m follow-up observations. Broad-band and spectroscopic observations of the spectral energy distribution reveals a sharp break at optical wavelengths which is interpreted as a Ly alpha absorption edge at 6700 Angstrom. This places GRB 000131 at a redshift of 4.500 +/- 0.015. The inferred isotropic energy release in gamma rays alone was similar to 10(54) erg (depending on the assumed cosmology). The rapid power-law decay of the afterglow (index alpha = 2.25, similar to bursts with a prior break in the lightcurve), however, indicates collimated outflow which relaxes the energy requirements by a factor of < 200. The afterglow of GRB 000131 is the first to be identified with an 8-m class telescope. C1 Univ Oulu, Div Astron, Oulu 90014, Finland. Univ Copenhagen, Astron Observ, Copenhagen 2100 0, Denmark. CNR, Ctr Astron Infrarossa & Studio Mezzo Interstellar, I-50125 Florence, Italy. Danish Space Res Inst, Copenhagen 2100 0, Denmark. European So Observ, D-85748 Garching, Germany. Univ Alabama, Huntsville, AL 35812 USA. NASA, Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Aarhus, Inst Phys & Astron, Aarhus 8000 C, Denmark. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. CNR, Inst Tecnol & Studio Radiazoni Extraterresti, I-40129 Bologna, Italy. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sterrenkundig Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Univ Oslo, Inst Theoret Astrophys, N-0315 Oslo, Norway. RP Andersen, MI (reprint author), Univ Oulu, Div Astron, POB 3000, Oulu 90014, Finland. EM Michael.Andersen@oulu.fi RI Fynbo, Johan/L-8496-2014; Christensen, Lise/M-5301-2014; Hjorth, Jens/M-5787-2014; Vestergaard, Marianne/M-5247-2014; Jensen, Brian Lindgren/E-1275-2015; Palazzi, Eliana/N-4746-2015 OI Fynbo, Johan/0000-0002-8149-8298; Christensen, Lise/0000-0001-8415-7547; Hjorth, Jens/0000-0002-4571-2306; Vestergaard, Marianne/0000-0001-9191-9837; Jensen, Brian Lindgren/0000-0002-0906-9771; NR 45 TC 123 Z9 126 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 DEC PY 2000 VL 364 IS 1 BP L54 EP L61 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 392LJ UT WOS:000166412300010 ER PT J AU Brandner, W Sheppard, S Zinnecker, H Close, L Iwamuro, F Krabbe, A Maihara, T Motohara, K Padgett, DL Tokunaga, A AF Brandner, W Sheppard, S Zinnecker, H Close, L Iwamuro, F Krabbe, A Maihara, T Motohara, K Padgett, DL Tokunaga, A TI VLT-detection of two edge-on Circumstellar Disks in the rho Oph dark cloud SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : circumstellar matter; stars : formation; stars : pre-main sequence; Galaxy : open clusters and associations : individual : rho Ophiuchi dark cloud ID YOUNG STELLAR OBJECTS; OPHIUCHI MAIN CLOUD; T-TAURI STARS; PROTOSTELLAR DISKS; IMAGING SURVEY; HH 30; POPULATION; CLUSTER; CORE; MULTIPLICITY AB Observations of the rho Ophiuchi star forming region with VLT ANTU and ISAAC under 0." 35 seeing conditions reveal two bipolar reflection nebulosities intersected by central dust lanes. The sources (OphE-MM3 and CRBR 2422.8-3423). can be identified as spatially resolved circumstellar disks viewed close to edge-on, similar to edge-on disk sources discovered previously in the Taurus and Orion star forming regions. Millimeter continuum fluxes yield disk masses of the order of 0.01 M., i.e. about the mass deemed necessary for the minimum solar nebula. Follow-up spectroscopic observations with SUBARU and CISCO show that both disk sources exhibit featureless continua in the K-band. No accretion or outflow signatures were detected. The slightly less edge-on orientation of the disk around CRBR 2422.8-3423 compared to HH 30 leads to a dramatic difference in the flux seen in the ISOCAM 4.5 mum to 12 mum bands. The observations confirm theoretical predictions on the effect of disk geometry and inclination angle on the spectral energy distribution of young stellar objects with circumstellar disks. C1 Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Astrophys Inst Potsam, D-14482 Potsdam, Germany. European So Observ, D-85748 Garching, Germany. Kyoto Univ, Dept Phys, Kyoto 6068502, Japan. Deutsch Zentrum Luft & Raumfahrt, Inst WEltrumsensorik & Planetenerkundung, D-12489 Berlin, Germany. Astron Observ Japan, Subaru Telescope, Hilo, HI 96720 USA. CALTECH, Jet Prop Lab, IPAC 10022, Pasadena, CA 91125 USA. RP Brandner, W (reprint author), Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA. EM brandner@ifa.hawaii.edu; sheppard@ifa.hawaii.edu; hzinnecker@aip.de; lclose@eso.org; iwamuro@cr.scphys.kyoto-u.ac.jp; krabbe@dlr.de; maihara@cr.scphys.kyoto-u.ac.jp; motohara@subaru.naoj.org; dlp@ipac.caltech.edu; tokunaga@ifa.hawaii.edu RI MOTOHARA, KENTARO/G-4905-2014 OI MOTOHARA, KENTARO/0000-0002-0724-9146 NR 38 TC 39 Z9 39 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 EI 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD DEC PY 2000 VL 364 IS 1 BP L13 EP L18 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 392LJ UT WOS:000166412300003 ER PT J AU Bicay, MD Stepanian, JA Chavushyan, VH Erastova, LK Ayvazyan, VT Seal, J Kojoian, G AF Bicay, MD Stepanian, JA Chavushyan, VH Erastova, LK Ayvazyan, VT Seal, J Kojoian, G TI Accurate optical positions for 2978 objects from the Second Byurakan Survey (SBS) with the Digitized Sky Survey SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE surveys; catalogs : active; galaxies; quasars ID FINDING CHARTS; GALAXIES; QUASARS; SYSTEM AB Optical positions of 2978 objects listed in the Second Byurakan Survey (SBS) were obtained using the Digitized Sky Survey (DSS), and are given with an rms uncertainty similar to1 arcsec in each coordinate. C1 Russian Acad Sci, Special Astrophys Observ, Karachai Cherkessia 357147, Russia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Inst Nacl Astrofis Opt Elect, Puebla 72000, Mexico. Byurakan Astrophys Observ, Byurakan, Armenia. Armenian State Pedag Inst, Dept Phys & Astron, Yerevan 375010, Armenia. Cambridge CR&D, Sidney, IL 61877 USA. Univ Wisconsin, Dept Phys & Astron, Eau Claire, WI 54702 USA. RP Stepanian, JA (reprint author), Russian Acad Sci, Special Astrophys Observ, Karachai Cherkessia 357147, Russia. NR 24 TC 24 Z9 24 U1 0 U2 3 PU E D P SCIENCES PI LES ULIS CEDEXA PA 7, AVE DU HOGGAR, PARC D ACTIVITES COURTABOEUF, BP 112, F-91944 LES ULIS CEDEXA, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD DEC PY 2000 VL 147 IS 2 BP 169 EP 173 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385UD UT WOS:000166021400001 ER PT J AU Ghigna, S Moore, B Governato, F Lake, G Quinn, T Stadel, J AF Ghigna, S Moore, B Governato, F Lake, G Quinn, T Stadel, J TI Density profiles and substructure of dark matter halos: Converging results at ultra-high numerical resolution SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : theory; dark matter; galaxies : clusters : general; galaxies : halos; large-scale structure of universe; methods : numerical ID LARGE-SCALE STRUCTURE; HIERARCHICAL UNIVERSE; GALAXY CLUSTERS; COSMOLOGICAL MODELS; DYNAMICAL FRICTION; GALACTIC HALOS; VELOCITY BIAS; EVOLUTION; MASS; SATELLITES AB Can dissipationless N-body simulations be used to reliably determine the structural and substructure properties of dark matter halos? A large simulation of a galaxy cluster in a cold dark matter universe is used to increase the force and mass resolution of current "high-resolution simulations" by almost an order of magnitude to examine the convergence of the important physical quantities. The cluster contains similar to5 million particles within the final virial radius, R-vir similar or equal to 2 MPC (with H-0 = 50 km s(-1) Mpc(-1)), and is: simulated using a force resolution of 1.0 kpc (equivalent to 0.05% of R-vir); the final virial mass is 4.3 x 10(14) M-., equivalent to a circular velocity of v(circ) (GM/R)(1/2) similar or equal to 1000 km s(-1) at the virial radius. The central density profile has a logarithmic slope of -1.5, identical to lower resolution studies of the same halo, indicating that the profiles measured from simulations of this resolution have converged to the "physical" limit down to scales of a few kpc (similar to0.2% of R-vir). In addition, the abundance and properties of substructure are consistent with those derived from lower resolution runs; from small to large galaxy scales (v(circ) > 100 km s(-1), m > 10(11) M-.), the circular velocity function and the mass function of substructures can be approximated by power laws with slopes of similar to -4 and similar to -2, respectively. At the current resolution, overmerging (a numerical effect that leads to structureless virialized halos in low-resolution N-body simulations) seems to be globally unimportant for substructure halos with circular velocities of v(circ) > 100 km s(-1) (similar to 10% of the cluster's v(circ)). We can identify subhalos orbiting in the very central region of the cluster (R less than or similar to 100 kpc), and we can trace most of the cluster progenitors from high redshift to the present. The object at the cluster center (the dark matter analog of a cD galaxy) is assembled between z = 3 and z = 1 from the merging of a dozen halos with v(circ) greater than or similar to 300 km s(-1). Tidal stripping and halo-halo collisions decrease the mean circular velocity of the substructure halos by approximate to 20% over a 5 billion yr period. We use the sample of 2000 substructure halos to explore the possibility of biases using galactic tracers in clusters: the velocity dispersions of the halos globally agree with the dark matter within less than or similar to 10%, but the halos are spatially antibiased, and in the very central region of the cluster (R/R-vir < 0.3) they show positive velocity bias (b(v) sigma (v3D,halos)/sigma (v3D,DM) similar or equal to 1.2-1.3); however, this effect appears to depend on numerical resolution. C1 Univ Durham, Dept Phys, Durham, England. Osserv Brera Merate, Milan, Italy. Univ Washington, Dept Astron, Seattle, WA 98195 USA. NASA, HPCC, Washington, DC 20546 USA. RP Ghigna, S (reprint author), Univ Durham, Dept Phys, Durham, England. NR 62 TC 456 Z9 456 U1 0 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 616 EP 628 DI 10.1086/317221 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100002 ER PT J AU Rol, E Wijers, RAMJ Vreeswijk, PM Kaper, L Galama, TJ van Paradijs, J Kouveliotou, C Masetti, N Pian, E Palazzi, E Frontera, F van den Heuvel, EPJ AF Rol, E Wijers, RAMJ Vreeswijk, PM Kaper, L Galama, TJ van Paradijs, J Kouveliotou, C Masetti, N Pian, E Palazzi, E Frontera, F van den Heuvel, EPJ TI GRB 990712: First indication of polarization variability in a gamma-ray burst afterglow SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; polarization; radiation mechanisms : nonthermal turbulence ID LIGHT CURVES; GRB-990510; FIREBALL; EMISSION; SIZE AB We report the detection of significant polarization in the optical afterglow of GRB 990712 on three instances: 0.44, 0.70, and 1.45 days after the gamma-ray burst, with (P, theta) being (2.9% +/- 0.4%, 121 degrees .1 +/- 3 degrees .5), (1.2% +/- 0.4%, 116 degrees .2 +/- 10 degrees .1), and (2.2% +/- 0.7%, 139 degrees .2 +/- 10 degrees .4), respectively. The polarization is intrinsic to the afterglow. The degree of polarization is not constant and is smallest at the second measurement. The polarization angle does not vary significantly during these observations. We find that none of the existing models predict such polarization Variations at a constant polarization angle; we suggest ways in which these models might be modified to accommodate the observed behavior of this afterglow. C1 Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. CALTECH, Pasadena, CA 91125 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Ferrara, Dept Phys, I-44100 Ferrara, Italy. RP Rol, E (reprint author), Univ Amsterdam, Astron Inst Anton Pannekoek, Kruislaan 403, NL-1098 SJ Amsterdam, Netherlands. RI Galama, Titus/D-1429-2014; Palazzi, Eliana/N-4746-2015; OI Galama, Titus/0000-0002-1036-396X; Palazzi, Eliana/0000-0002-8691-7666; Pian, Elena/0000-0001-8646-4858 NR 28 TC 42 Z9 43 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 707 EP 711 DI 10.1086/317256 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100010 ER PT J AU Chatzichristou, ET AF Chatzichristou, ET TI Multicolor optical imaging of infrared-warm Seyfert galaxies. II. Optical and infrared properties and their correlations SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : interactions; galaxies : photometry; galaxies : Seyfert; infrared : galaxies ID POINT-SOURCE CATALOG; IRAS SOURCES; MARKARIAN GALAXIES; EMISSION; SPECTROSCOPY; NUCLEI; MODELS AB This paper is the second in a series, studying the optical properties of a sample of mid-IR-warm Seyfert galaxies and a control sample of mid-IR-cold galaxies. The present paper is devoted to aperture photometry. We discuss nuclear (within the central 2 kpc) and disk optical properties and their correlations with IR properties. Our results suggest intrinsic differences in the host properties of the Seyfert type 1 and 2 nuclei. We find a transition in the observed optical and IR properties from the cold to the warm Seyfert 2 and Seyfert 1 samples, with a partial overlap between the first two. This is in the sense of (1) increasing nuclear optical luminosities and bluer nuclear colors, (2) decreasing disk optical luminosities and sizes, and (3) increasing 25 mum luminosities, decreasing far-IR excess (L-FIR/L-B) and IR loudness (alpha ((V,25)), alpha ((V,60))), and bluer alpha ((25,60)), and alpha ((12,100)) colors. We interpret these results as indicating larger dust content and disk star formation for Seyfert 2s, while the optical properties of Seyfert Is are mostly dominated by their nuclei. The 25 mum emission of the warm sample is mainly due to the active galactic nucleus (AGN) thermal component, although in Seyfert 2s it is probably further enhanced by disk star formation. The far-IR (60-100 mum) luminosity traces mainly emission at large scales (the host disks for both Seyfert types). In the IR-cold galaxies, the bulk of IR emission at all wavelengths appears to be dominated by dust in their disks. C1 Leiden Observ, NL-2300 RA Leiden, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chatzichristou, ET (reprint author), Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands. NR 11 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 712 EP 733 DI 10.1086/317226 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100011 ER PT J AU Nandra, K Le, T George, IM Edelson, RA Mushotzky, RF Peterson, BM Turner, TJ AF Nandra, K Le, T George, IM Edelson, RA Mushotzky, RF Peterson, BM Turner, TJ TI The origin of the X-ray and ultraviolet emission in NGC 7469 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 7469); galaxies : nuclei; galaxies : Seyfert; ultraviolet : galaxies; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; BROAD-LINE REGION; SEYFERT-1 GALAXIES; BLACK-HOLE; SPECTRAL VARIABILITY; ACCRETION-DISK; COLD MATTER; IRON LINE; MAGNETIC FLARES; CYGNUS X-1 AB We present a spectral analysis of a similar to 30 day, near-continuous observation of the Seyfert 1 galaxy NGC 7469 with RXTE. Daily integrations show strong spectral changes during the observation. Our main result is that we find the X-ray spectral index to be correlated with the UV flux. Furthermore, the broadband X-ray photon flux is also correlated with the UV continuum. These correlations point toward a model in which the X-rays originate via thermal Comptonization of UV seed photons. Furthermore, the UV is also correlated with the extrapolation of the X-ray power law into the soft X-ray/EUV region. Our,data analysis therefore reopens the possibility that the UV photons and their variability arise from reprocessing, as long as the primary source of heating is photoelectric absorption in the reprocessor, rather than Compton downscattering. A coherent picture of the X-ray/UV variability can therefore be constructed whereby absorption and reprocessing of EUV/soft X-rays in a standard accretion disk produce a variable seed photon distribution, which is in turn upscattered into the X-ray band. We also find a significant correlation between the 2-10 keV flux and the 6.4 keV iron K alpha line, suggesting that at least some portion of the line originates within similar to1 light day of the X-ray continuum source. Neither the power-law photon index nor the Compton reflection component are correlated with the 2-10 keV flux. The latter is not correlated with the iron K alpha line flux either. We do find an apparent correlation between the X-ray spectral index and the strength of the Compton reflection component. In an Appendix we show, however, that this can be produced by a combination of statistical and systematic errors. We conclude that the apparent variations in the Compton reflection component may be an artifact of these effects. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. George Mason Univ, Dept Phys & Astron, Fairfax, VA 22030 USA. Univ Calif Los Angeles, Dept Astron, Los Angeles, CA 90024 USA. Univ Leicester, Xray Astron Grp, Leicester LE1 7RH, Leics, England. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Univ Maryland, Baltimore, MD 21250 USA. RP Nandra, K (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 77 TC 96 Z9 96 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 734 EP 746 DI 10.1086/317237 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100012 ER PT J AU Kraemer, SB Crenshaw, DM AF Kraemer, SB Crenshaw, DM TI Resolved spectroscopy of the narrow-line region in NGC 1068. III. Physical conditions in the emission-line gas SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 1068); galaxies : Seyfert ID ACTIVE GALACTIC NUCLEI; SEYFERT-2 GALAXY NGC-1068; IONIZING CONTINUUM; SPECTRA; MODELS; DUST; EXCITATION; NGC-4151; QUASARS; IMAGE AB The physical conditions in the inner narrow-line region (NLR) of the Seyfert 2 galaxy NGC 1068 are examined using ultraviolet and optical spectra and photoionization models. The spectra were taken with the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS), through the 0."1 x 52."0 slit, covering the full STIS 1200-10000 Angstrom waveband. The slit was centered on a position 0." 14 north of the optical continuum peak (or "hot spot") at a position angle of 202 degrees, bisecting the brighter part of the biconical emission-line region. We have measured the emission-line fluxes for a region extending 3.degrees8 northeast (similar to 270 pc) to 1."8 southwest (similar to 130 pc) of this point. The emission lines on each side show evidence of two principal kinematic components, one blueshifted with respect to the systemic velocity and the other redshifted (the kinematics were discussed in a separate paper). Based on the photoionization modeling results, we find that the physical conditions vary among these four quadrants. (1) The emission-line gas in the blueshifted northeast quadrant is photoionized by the hidden central source out to similar to 100 pc, at which point we find evidence of another source of ionizing radiation, which may be due to fast (similar to 1000 km s(-1)) shocks resulting from the interaction of the emission-line knots and the interstellar medium. Interestingly, this occurs at approximately the location where the knots begin to show signs of deceleration. (2) The gas in the redshifted northeast quadrant is photoionized by continuum radiation that has been heavily absorbed by gas within similar to 30 pc of the central source. We find no strong evidence of the effects of shocks in this component. (3) The redshifted emission-line gas in the southwest quadrant is photoionized by unabsorbed continuum from the central source, similar to that in the inner similar to 100 pc of the blueshifted northeast quadrant. Finally, (4) the emission-line spectrum of the blueshifted southwest quadrant appears to be the superposition of highly ionized, tenuous component within the ionization cone and gas outside the cone, the latter photoionized by scattered continuum radiation. There are several implications of this complicated physical scenario. First, the hidden active nucleus is the dominant source of ionizing radiation in the inner NLR. The absorption of continuum radiation along the line of sight to the redshifted northeast quadrant may result from the intersection of the ionization cone and the plane of the host galaxy. Finally, the evidence for shock-induced continuum radiation at the point where the emission-line knots begin to decelerate indicates that the deceleration is due to the interaction of emission-line knots with slower moving gas, such as the interstellar medium of NGC 1068. C1 Catholic Univ Amer, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kraemer, SB (reprint author), Catholic Univ Amer, NASA, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. NR 55 TC 65 Z9 65 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 763 EP 779 DI 10.1086/317246 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100014 ER PT J AU Grady, CA Devine, D Woodgate, B Kimble, R Bruhweiler, FC Boggess, A Linsky, JL Plait, P Clampin, M Kalas, P AF Grady, CA Devine, D Woodgate, B Kimble, R Bruhweiler, FC Boggess, A Linsky, JL Plait, P Clampin, M Kalas, P TI Stis coronagraphic imaging of the Herbig Ae star: HD 163296 SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; planetary systems; stars : individual (HD 163296); stars : pre-main-sequence ID MODEL SCATTERING ENVELOPES; YOUNG STELLAR OBJECTS; X-RAY-EMISSION; AE/BE STARS; CIRCUMSTELLAR DISKS; PLANET FORMATION; HIGH-RESOLUTION; BETA-PICTORIS; HD-163296; SYSTEMS AB Coronagraphic imaging with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope reveals a similar to 450 AU radius circumstellar disk around the Herbig Ae star HD 163296. A broadband (0.2-1.0 mum) reflected light image shows the disk oriented at a position angle of 140 degrees +/- 5 degrees and inclined to our line of sight by similar to 60 degrees +/- 5 degrees. The disk includes an annulus of reduced scattering at 325 AU and exhibits a flat trend of surface brightness in to 180-122 AU (1."5-1 "), consistent with a cleared central zone. For r greater than or equal to 370 AU the disk surface brightness drops as r to the approximately -3.5 power. The disk cannot: be traced beyond 450 AU in our data. The disk is accompanied by a chain of nebulosities at P.A. = 42 degrees .5 +/- 3 degrees .5, compatible with detection of a Herbig-Haro flow. The HD 163296 disk most closely resembles the disk of HD 141569. As in the HD 141569 system, the dynamical effects of a planet may be necessary to explain the structure in the outer disk. C1 NOAO, STIS, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Catholic Univ Amer, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. Natl Inst Stand & Technol, Boulder, CO 80309 USA. Adv Comp Concepts Inc, Potomac, MD 20854 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. RP Grady, CA (reprint author), NOAO, STIS, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Clampin, mark/D-2738-2012; Kimble, Randy/D-5317-2012 NR 48 TC 95 Z9 95 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 895 EP 902 DI 10.1086/317222 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100026 ER PT J AU Willacy, K Langer, WD AF Willacy, K Langer, WD TI The importance of photoprocessing in protoplanetary disks SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; ISM : abundances; ISM : molecules; solar system : formation; stars : formation; stars : pre-main-sequence ID DENSE INTERSTELLAR CLOUDS; RAY-INDUCED DESORPTION; INTER-STELLAR CLOUDS; T-TAURI STARS; CIRCUMSTELLAR DISKS; GRAIN CHEMISTRY; DUST EMISSION; DM-TAU; GAS; MOLECULES AB Midplane models of protoplanetary disks iind that the cold temperatures in the outer parts of the disk ensure that virtually all molecules are accreted onto the grains. However, molecules in the gas are observed at these radii. One possible explanation is that the emission arises from above the midplane, possibly in a heated layer at the surface of a flared disk. Models which take into account the vertical chemical distribution of molecules and can calculate column densities are therefore required for comparison with observations. We present the results of a calculation of the time-dependent two-dimensional chemical structure of a flared protoplanetary disk which includes photoprocesses driven by both the stellar and interstellar radiation fields. Three layers are found in the disk consistent with previous work. In the upper layer photodissociation produces large abundances of atoms and ions. Below this molecules are shielded and can avoid dissociation, although sufficient radiation is present to remove molecules from the grain surfaces by photodesorption. The majority of the observable species come from this layer. Closer to the midplane of the disk, freezeout removes molecules from the gas. We find that photodesorption can account for the observed column densities if the photodesorption yield is higher than 10(-3) molecules per photon. These results indicate that many observed molecules trace the physical and chemical conditions in the surface regions rather than the midplane although the contribution of the heated surface layer to the column densities is minimal. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Willacy, K (reprint author), CALTECH, Jet Prop Lab, MS 169-327, Pasadena, CA 91109 USA. NR 42 TC 101 Z9 101 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 903 EP 920 DI 10.1086/317236 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100027 ER PT J AU Osten, RA Brown, A Ayres, TR Linsky, JL Drake, SA Gagne, M Stern, RA AF Osten, RA Brown, A Ayres, TR Linsky, JL Drake, SA Gagne, M Stern, RA TI Radio, X-ray, and extreme-ultraviolet coronal variability of the short-period RS canum venaticorum binary sigma(2) coronae borealis SO ASTROPHYSICAL JOURNAL LA English DT Article DE radio continuum : stars; stars : activity; stars : coronae; stars : late-type; X-rays : stars ID CHROMOSPHERICALLY ACTIVE BINARIES; H-ALPHA EMISSION; CA-II-H; SOLAR-FLARES; CVN BINARIES; AU-MICROSCOPII; AR-LACERTAE; CONTINUUM EMISSION; QUIESCENT EMISSION; STELLAR CORONAE AB We present the results of a coordinated observing campaign on the short-period (1.14 days) RS CVn binary sigma (2) Coronae Borealis with the VLA, ASCA, and RXTE. We also discuss earlier observations of the same system obtained by the Extreme Ultraviolet ExpEorer (EUVE). Dramatic coronal variability is present in all of these observations across the electromagnetic spectrum. sigma (2) CrB undergoes frequent large flares that occur close together in time. Radio flares are unambiguously correlated with X-ray flares; the X-ray flares peak as much as 1.4 hr before the corresponding radio maxima. Response to flares is more rapid in higher energy X-ray bandpasses, signaling an increase in temperature during the course of the flare. Flares are seen more frequently in the harder RXTE bandpass than in simultaneously taken ASCA observations. There is greater contrast between flaring and nonflaring conditions in the RXTE light curve. Complex Raring is seen in the radio at 3 and 6 cm, consistent with optically thin nonthermal gyrosynchrotron emission for most of the duration of the observation. Bursts of left-circularly polarized emission at 20 cm lasting less than or equal to 5 minutes appear to be due to a coherent emission process. EUVE spectra reveal coronal material at n(e) less than or equal to 10(12) cm(-3), With no discernible density differences between flaring and quiescent time intervals. Quiescent ASCA spectra show lower than solar photospheric abundances with iron depleted by a factor of 4 from the solar photospheric value. The abundances increase during a large flare observed with ASCA, with iron enhanced to the solar photospheric value during the rise phase of the hare. Two-temperature fits to extracted spectra show a low-temperature quiescent value of 8 MK and a high-temperature component that varies from 22 MK during quiescence to 50 MK at the peak of the flare. Emission measure distributions measured from the ASCA observations are consistent with the temperatures derived from the discrete two-temperature fits and indicate the presence of very hot (> 100 MK) plasma during the rise phase of the ASCA Bare. Many of the flares observed with EUVE, ASCA, and RXTE show a double exponential decay phase, further highlighting the importance of this phenomenon in diagnosing flaring conditions. We also find that the observed second decay timescale cannot be explained by some of the currently used flare parameterizations. C1 Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Colorado, JILA, Boulder, CO 80309 USA. NIST, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, HEASARC, Greenbelt, MD 20771 USA. W Chester Univ, W Chester, PA 19383 USA. Lockheed Martin Solar & Astrophys Lab, Palo Alto, CA 94304 USA. RP Osten, RA (reprint author), Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. RI Gagne, Marc/C-1130-2013 NR 79 TC 37 Z9 37 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 953 EP 976 DI 10.1086/317249 PN 1 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100033 ER PT J AU Araya-Gochez, RA Harding, AK AF Araya-Gochez, RA Harding, AK TI Cyclotron-line features from near-critical fields. II. On the effect of anisotropic radiation fields SO ASTROPHYSICAL JOURNAL LA English DT Article DE line : profiles; pulsars : general; scattering; stars : magnetic fields; stars : neutron ID STRONG MAGNETIC-FIELDS; GAMMA-RAY BURSTS; RESONANT SCATTERING; PULSAR ATMOSPHERES; NEUTRON STARS; ACCRETION; SPECTRA AB We assess the impact of radiation anisotropy on the line shapes that result from relativistic magnetic Compton scattering in the low-density/high-field regime. A Monte Carlo implementation of radiation transport allows for spatial diffusion of photons in arbitrary geometries and accounts for relativistic angular redistribution. The cross section includes natural line widths and photon "spawning" from up to fourth-harmonic photons. In our first paper we noted that even if the photon injection is isotropic, a strongly anisotropic radiation field rapidly ensues. We now investigate the angular distribution of cyclotron spectra emerging from an internally irradiated magnetized plasma with a prescribed global geometry (either cylindrical or plane parallel) and the effects of anisotropic photon injection on the line shapes. Varying the input angular distribution permits a better understanding of the line formation process in more realistic scenarios where the radiative mechanisms are influenced by the intrinsic anisotropy of the field and by moderate relativistic beaming. In general, the line features are most pronounced along the directions of the anisotropic continuum injection and tend to be weakened in other directions, relative to the line features resulting from an isotropic continuum injection. We find that the enhancements at the line wings of the fundamental, which appear prominently in the case of isotropic continuum injection, are strongly suppressed along the direction of anisotropy in the case of beamed continuum injection, regardless of geometry or beaming pattern. C1 Univ Costa Rica, Escuela Fis, Lab Invest Astrofis, San Jose, Costa Rica. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Univ Costa Rica, Escuela Fis, Lab Invest Astrofis, San Jose, Costa Rica. RI Harding, Alice/D-3160-2012 NR 37 TC 52 Z9 52 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 1067 EP 1080 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100040 ER PT J AU Weiner, J Danchi, WC Hale, DDS McMahon, J Townes, CH Monnier, JD Tuthill, PG AF Weiner, J Danchi, WC Hale, DDS McMahon, J Townes, CH Monnier, JD Tuthill, PG TI Precision measurements of the diameters of alpha Orionis and o Ceti at 11 microns SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : stars; instrumentation : interferometers; stars : fundamental parameters; stars : individual (alpha Orionis, o Ceti) ID INFRARED ANGULAR DIAMETER; EFFECTIVE TEMPERATURE; BETELGEUSE; GIANTS AB The angular diameters of alpha Orionis and o Ceti were measured at a wavelength of 11.15 mum using the two-telescope Infrared Spatial Interferometer (ISI). Based on fitting the visibility data to uniform disk models, the diameter of alpha Orionis is 54.7 +/- 0.3 mas and that of o Ceti at phase 0.90 is 47.8 +/- 0.5 mas. These diameters are the most precise ever measured in the mid-infrared, due in part to the addition of a 56 m baseline to the ISI, which provided sufficient resolution to observe the first zero in the visibility function of the stellar disks. Moreover, the effects of limb darkening and stellar hot spots are small at these wavelengths. Theoretically estimated limb-darkening effects indicate the actual diameters are approximately 1% +/- 0.5% larger than the uniform disk approximation, or 55.2 +/- 0.5 and 48.2 +/- 0.6 mas for alpha Orionis and o Ceti, respectively. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ctr Astrophys, Cambridge, MA 02138 USA. Univ Sydney, Sch Phys, Chatterton Astron Dept, Sydney, NSW 2006, Australia. RP Weiner, J (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NR 18 TC 43 Z9 43 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP 1097 EP 1100 DI 10.1086/317264 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FA UT WOS:000165931100042 ER PT J AU Baykal, A Stark, MJ Swank, J AF Baykal, A Stark, MJ Swank, J TI Discovery of the orbit of the transient X-ray pulsar SAX J2103.5+4545 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : close; pulsars : individual (SAX J2103.5+4545); stars : neutron; X-rays : stars ID TIMING EXPLORER AB Using X-ray data from the Rossi X-Ray Timing Explorer (RXTE), we carried out a pulse-timing analysis of the transient X-ray pulsar SAX J2103.5+4545. An outburst was detected by the All-Sky Monitor (ASM) in 1999 October 25 and reached a peak X-ray brightness of 27 mcrab on October 28. Between November 19 and December 27, the RXTE Proportional Counter Array (PCA) carried out pointed observations that provided us with pulse arrival times. These yield an eccentric orbit (e = 0.4 +/- 0.2) with an orbital period of 12.68 +/- 0.25 days and a light-travel time across the projected semimajor axis of 72 +/- 6 s. The pulse period was measured to be 358.62171 +/- 0.00088 s, and the spin-up rate was (2.50 +/- 0.15) x 10(-13) Hz s(-1). The ASM data for the 1997 February-September outburst, in which F. Hulleman, J. J. M. in 't Zand, & J. Heise discovered SAX J2103.5 + 4545 using BeppoSAX, are modulated at timescales close to the orbital period. Folded light curves of the 1997 ASM data and the 1999 PCA data are similar and show that the intensity increases at periastron passages. C1 Middle E Tech Univ, Dept Phys, Div Astrophys, TR-06531 Ankara, Turkey. Marietta Coll, Dept Phys, Marietta, OH 45750 USA. NASA, Goddard Space Flight Ctr, Lab High Energy Astrophys, Greenbelt, MD 20771 USA. RP Baykal, A (reprint author), Middle E Tech Univ, Dept Phys, Div Astrophys, TR-06531 Ankara, Turkey. RI Swank, Jean/F-2693-2012 NR 10 TC 27 Z9 27 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP L129 EP L132 DI 10.1086/317320 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FC UT WOS:000165931300011 ER PT J AU Jura, M Chen, C Werner, MW AF Jura, M Chen, C Werner, MW TI The dying wind around HD 56126, a post-asymptotic giant branch carbon star SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; stars : AGB and post-AGB; stars : winds, outflows ID CIRCUMSTELLAR DUST SHELLS; INTERMEDIATE-MASS STARS; LONG-PERIOD VARIABLES; PROTOPLANETARY NEBULAE; STELLAR EVOLUTION; MAGNETIC-FIELD; EVOLVED STARS; PLANETARY-NEBULAE; RICH STARS; V-HYDRAE AB We have used the Keck I telescope to resolve at mid-infrared wavelengths the dust emission from HD 56126 (IRAS 07134+1005), a post-asymptotic giant branch carbon star with a detached dust shell. The gross morphology of the image can be explained by a strong wind that started to die about 1500 yr ago. If the star had an effective temperature T-* near 2600 K when it was losing similar to3 x 10(-5) M-. yr(-1), then during the past 1500 yr, the average value of dT(*)/dt has been 2.2 K yr(-1). With such a time variation of the effective temperature, the 11.7 pm image can be approximately reproduced if the mass-loss rate varied as T-*(-8.26), as proposed in recent models for dust-driven winds. Since the mass-loss rate appears to be very sensitive to the effective temperature of the star, we speculate that the observed deviations from spherical symmetry of the dust shell can be explained by plausible variations in the surface temperature of the mass-losing star caused by rotation and/or magnetic fields. C1 Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jura, M (reprint author), Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. NR 41 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP L141 EP L144 DI 10.1086/317307 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FC UT WOS:000165931300014 ER PT J AU Thejappa, G MacDowall, RJ AF Thejappa, G MacDowall, RJ TI Langmuir waves in the vicinity of interplanetary shocks and the consequences for type II burst models SO ASTROPHYSICAL JOURNAL LA English DT Article DE shock waves; Sun : radio radiation ID EARTHS BOW SHOCK; ULYSSES OBSERVATIONS; RADIO EMISSIONS; ELECTRONS; UPSTREAM; ACCELERATION; REGIONS; PLASMA; DRIVEN AB The in situ wave data obtained by the Ulysses Unified Radio And Plasma wave experiment in the vicinity of a large number of interplanetary shocks show that Langmuir waves (1) are observed in only similar to 15% of the interplanetary shocks, (2) occur mostly in the upstream regions, and (3) are produced in the vicinity of both quasi-parallel Q(parallel to) and quasi-perpendicular Q(perpendicular to) shocks and that (4) Langmuir wave-producing shocks are supercritical. Since Langmuir waves are the essential ingredients for the solar and interplanetary type II burst excitation, these observations imply that (1) the shock responsible for type II emission can be either ell with a shock normal angle, theta (B,n) less than or equal to pi /4, or Q(perpendicular to) with theta (B,n) > pi /4, (2) type II bursts are excited in the upstream regions, (3) the theta (B,n) need not be close to similar to pi /2 for either the excitation or the clumpiness of the type II bursts, and (4) type II shocks are mostly supercritical. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Thejappa, G (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RI MacDowall, Robert/D-2773-2012 NR 28 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP L163 EP L167 DI 10.1086/317303 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FC UT WOS:000165931300019 ER PT J AU Yaqoob, T Serlemitsos, P AF Yaqoob, T Serlemitsos, P TI A broad FeK alpha emission line in the X-ray spectrum of the quasar 3C 273 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; quasars : emission lines; quasars : individual (3C 273); X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; ASCA OBSERVATIONS; 3C-273; REFLECTION; BEPPOSAX; 3C273 AB The Fe K alpha line, an important physical diagnostic in the X-ray spectra of active galaxies (AGNs) and quasars, has been notoriously difficult to measure in the high-luminosity, radio-loud quasar 3C 273 (z = 0.158). On the few occasions that it has been detected, its intrinsic width has been thought to be narrow (FWHM < 10,000 km s(-1)), with an equivalent width (EW) of a few tens of eV. This was consistent with the general trend that as one goes from low- to high-luminosity AGNs, the Fe K line goes from being strong (EW similar to 200-300 eV) and broad (FWHM similar to 10(5) km s(-1)) to being weak and narrow, or absent altogether. Here we present the results of new ASCA and RXTE observations, together with archival ASCA data, and show for the first time that the Fe K alpha line in 3C 273 is as broad as those seen in Seyfert 1 galaxies. The line is resolved in two of the observations, with a mean Gaussian width of 0.8 +/- 0.3 keV, corresponding to a FWHM of similar to 0.3 +/- 0.1c. The smallest and largest equivalent widths measured are 43(-34)(+43) and 133(-53)(+52) eV, respectively tin the quasar frame). The Compton-reflection continuum is less than 10% of that expected from a centrally illuminated semi-infinite, face-on, Compton-thick disk, confirming previous studies that Compton reflection is negligible in 3C 273. The largest values of the Fe K alpha line EW are underpredicted if the line originates in the disk, unless a time lag longer than several days between line and continuum and/or an overabundance of Fe is invoked. We cannot unambiguously constrain the disk inclination angle. About 60 degrees is preferred for a cold disk, while a face-on disk is allowed if the ionization state of Fe is H-like. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. RP Yaqoob, T (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 20 TC 24 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD DEC 1 PY 2000 VL 544 IS 2 BP L95 EP L99 DI 10.1086/317318 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 384FC UT WOS:000165931300004 ER PT J AU Kuchinski, LE Freedman, WL Madore, BF Trewhella, M Bohlin, RC Cornett, RH Fanelli, MN Marcum, PM Neff, SG O'Connell, RW Roberts, MS Smith, AM Stecher, TP Waller, WH AF Kuchinski, LE Freedman, WL Madore, BF Trewhella, M Bohlin, RC Cornett, RH Fanelli, MN Marcum, PM Neff, SG O'Connell, RW Roberts, MS Smith, AM Stecher, TP Waller, WH TI Comparing galaxy morphology at ultraviolet and optical wavelengths SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE galaxies : structure; ultraviolet : galaxies ID STAR-FORMING GALAXIES; IMAGING TELESCOPE; ELLIPTIC GALAXIES; NEARBY GALAXIES; COLOR GRADIENTS; PHOTOMETRY; IMAGES; EMISSION; DUST; M101 AB We have undertaken an imaging survey of 34 nearby galaxies in far-ultraviolet (FUV, similar to 1500 Angstrom) and optical (UBVRI) passbands to characterize galaxy morphology as a function of wavelength. This sample, which includes a range of classical Hubble types from elliptical to irregular, with emphasis on spirals at low inclination angle, provides a valuable database for comparison with images of high-z galaxies whose FUV light is redshifted into the optical and near-infrared bands. Ultraviolet data are from the Ultraviolet Imaging Telescope (UIT) Astro-2 mission. We present images and surface brightness profiles for each galaxy, and we discuss the wavelength dependence of morphology for different Hubble types in the context of understanding high-z objects. In general, the dominance of young stars in the FUV produces the patchy appearance of a morphological type later than that inferred from optical images. Prominent rings and circumnuclear star formation regions are clearly evident in FUV images of spirals, while bulges, bars, and old, red stellar disks are faint to invisible at these short wavelengths. However, the magnitude of the change in apparent morphology ranges from dramatic in early-type spirals with prominent optical bulges to slight in late-type spirals and irregulars, in which young stars dominate both the UV and optical emission. Starburst galaxies with centrally concentrated, symmetric bursts display an apparent "E/SO" structure in the FUV, while starbursts associated with rings or mergers produce a peculiar morphology. We briefly discuss the inadequacy of the optically defined Hubble sequence in describing FUV galaxy images and estimating morphological k-corrections, and we suggest some directions for future research with this data set. C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Carnegie Inst Washington Observ, Pasadena, CA 91101 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS Corp, Greenbelt, MD 20771 USA. Univ N Texas, Dept Phys, Denton, TX 76023 USA. Texas Christian Univ, Dept Phys, Ft Worth, TX 76129 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. Tufts Univ, Dept Phys & Astron, Medford, MA 02155 USA. RP Kuchinski, LE (reprint author), CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, 4800 Oak Grove Dr, Pasadena, CA 91125 USA. NR 68 TC 66 Z9 66 U1 2 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD DEC PY 2000 VL 131 IS 2 BP 441 EP 463 DI 10.1086/317371 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 390KJ UT WOS:000166294000003 ER PT J AU Johnstone, D Wilson, CD Moriarty-Schieven, G Giannakopoulou-Creighton, J Gregersen, E AF Johnstone, D Wilson, CD Moriarty-Schieven, G Giannakopoulou-Creighton, J Gregersen, E TI Large-area mapping at 850 microns. I. Optimum image reconstruction from chop measurements SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE infrared : ISM : continuum; ISM : structure; methods : data analysis; submillimeter ID CLERK-MAXWELL-TELESCOPE; SCUBA; CLOUD AB We present results on the optimum reconstruction of chop data taken using the Submillimeter Common-User Bolometer Array on the James Clerk Maxwell Telescope. Using an artificial data set with known noise properties, we analyze three techniques for constructing images of the sky from the chop data: Emerson Fourier deconvolution, matrix inversion, and maximum entropy reconstruction. We conclude that a matrix inversion formulation via an iterative procedure produces the best image reconstructions. We apply the three reconstruction techniques to produce maps of the calibration point source CRL 618 and the rho Ophiuchi A core at 850 mum and use Wiener filtering to remove the high-frequency noise component from the matrix inversion method. C1 Univ Toronto, Dept Astron, Toronto, ON M5S 3H8, Canada. McMaster Univ, Dept Phys & Astron, Hamilton, ON L8S 4M1, Canada. Natl Res Council Canada, Joint Astron Ctr, Hilo, HI 96720 USA. CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. RP Johnstone, D (reprint author), Univ Toronto, Dept Astron, Toronto, ON M5S 3H8, Canada. NR 15 TC 43 Z9 43 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD DEC PY 2000 VL 131 IS 2 BP 505 EP 518 DI 10.1086/317379 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 390KJ UT WOS:000166294000006 ER PT J AU Brown, RG Fu, LL AF Brown, RG Fu, LL TI An examination of the spring 1997 mid-latitude east Pacific Sea Surface Temperature anomaly SO ATMOSPHERE-OCEAN LA English DT Article ID ATMOSPHERE-OCEAN INTERACTION; SPECIAL SENSOR MICROWAVE/IMAGER; CIRRUS CLOUDS; EL NINO; STRATOCUMULUS; SIMULATIONS; WATER; CIRCULATION; VARIABILITY; TIMESCALES AB We seek to document and explain the lifecycle of the warm Sea Surface Temperature (SST) anomaly that intensified and weakened off the west coast of the United States to peak anomalies of 4 degreesC during April-June 1997. We use remotely sensed observational data and model analyses to compute an energy budget for the warm anomaly. The bulk of the anomalous warming was confined to the top 50 m of ocean and occurred during May. The immediate cause for the warming was twofold: latent heat fluxes decreased in magnitude as a result of both lower wind speeds and positive moisture anomalies, while the net radiative flux into the ocean increased as a result of lower than normal functional cloud coverage. During June, the wind speed strengthened find became northerly resulting in larger than normal latent and sensible heat fluxes that weakened the SST anomaly Examination of the National Centers for Environmental Prediction (NCEP) 1000-mb geopotential height for May shows that the Aleutian low extended far south of its usual position and was responsible for the weaker southerly winds and suppressed latent heat fluxes in the warm anomaly area. Finally, Mle note that the near simultaneous appearance of this warm anomaly in conjunction with warm EI Nino waters off Pent makes EI Nino an unlikely trigger for the northeast Pacific warm anomaly We suggest a possible alternative scenario in which both events are remotely triggered By the intraseasonal oscillation. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fu, LL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 32 TC 4 Z9 4 U1 0 U2 0 PU CANADIAN METEOROLOGICAL OCEANOGRAPHIC SOC PI OTTAWA PA 150 LOUIS PASTEUR PVT., STE 112, MCDONALD BUILDING, OTTAWA, ONTARIO K1N 6N5, CANADA SN 0705-5900 J9 ATMOS OCEAN JI Atmos.-Ocean PD DEC PY 2000 VL 38 IS 4 BP 577 EP 599 PG 23 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA 392HY UT WOS:000166406700003 ER PT J AU Prassler, E Ritter, A Schaeffer, C Fiorini, P AF Prassler, E Ritter, A Schaeffer, C Fiorini, P TI A short history of cleaning robots SO AUTONOMOUS ROBOTS LA English DT Article DE cleaning robots; autonomous cleaning devices; automatic cleaning; autonomous vacuum cleaner; robotic floor scrubber; autonomous pool cleaner; robotic road sweeper AB The definition of the desired functions and the design of an ultimate versatile personal robot is an ongoing debate. Meanwhile, however, precursors of this yet to evolve species are well on their way to become commercial products. Cleaning robots for public environments as well as for private households seem to be able to provide the breakthrough which the designers of non-industrial robot systems have long awaited. This survey describes a selection of 30 different cleaning robots, with the first developments reaching back more than 15 years. With a few exceptions we have focused on floor cleaning, in particular indoor floor cleaning. We describe a variety of scrubbing and vacuuming robots which were developed for this task. The described systems range from heavy, large, and expensive industrial cleaning vehicles to small-size, light-weight, low-cost household devices. The survey does not include, however, systems for cleaning facades of buildings, or windows, or production tools. Although not all of the 30 cleaning robots abovementioned have yet reached the state of commercial products, their number alone certainly reflects the expectations regarding the economic value associated with the automation of cleaning tasks. In Europe only the estimates for the market for cleaning services range up to the order of US$ 100 billion per year. It is therefore not surprising that the cleaning industry and the manufacturers of cleaning devices are rather enthusiastic with respect to the automation of cleaning tasks using (semi-)autonomous mobile robot systems. C1 Res Inst Appl Knowledge Proc, D-89010 Ulm, Germany. Fraunhofer Inst Mfg Engn & Automat, D-70569 Stuttgart, Germany. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Prassler, E (reprint author), Res Inst Appl Knowledge Proc, POB 2060, D-89010 Ulm, Germany. RI Fiorini, Paolo/A-2603-2012 NR 3 TC 42 Z9 43 U1 6 U2 78 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0929-5593 J9 AUTON ROBOT JI Auton. Robot. PD DEC PY 2000 VL 9 IS 3 BP 211 EP 226 DI 10.1023/A:1008974515925 PG 16 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 372DN UT WOS:000165219200002 ER PT J AU Fiorini, P Prassler, E AF Fiorini, P Prassler, E TI Cleaning and household robots: A technology survey SO AUTONOMOUS ROBOTS LA English DT Article DE mechanical configuration; design requirements; control architecture; complete coverage ID MOBILE; COORDINATION AB This paper describes some of the main technology areas that have been actually used in the development of cleaning robots. The approach taken in this survey is to examine the characteristics of cleaning robots that have made successful laboratory demonstration or have become commercial products. We then identify the technology approach followed by the authors, and group their contributions in a few general areas. The result is a summary of used approaches to the solution of difficult, albeit very practical, problems in the area of autonomous execution of cleaning tasks. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. FAW Res Inst Appl Knowledge Proc, D-89081 Ulm, Germany. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Fiorini, Paolo/A-2603-2012 NR 58 TC 11 Z9 12 U1 3 U2 8 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0929-5593 EI 1573-7527 J9 AUTON ROBOT JI Auton. Robot. PD DEC PY 2000 VL 9 IS 3 BP 227 EP 235 DI 10.1023/A:1008954632763 PG 9 WC Computer Science, Artificial Intelligence; Robotics SC Computer Science; Robotics GA 372DN UT WOS:000165219200003 ER PT J AU Clancey, WJ AF Clancey, WJ TI Conceptual coordination bridges information processing and neurophysiology SO BEHAVIORAL AND BRAIN SCIENCES LA English DT Editorial Material AB Information processing theories of memory and skills can be reformulated in terms of how categories are physically and temporally related, a process called conceptual coordination. Dreaming can then be understood as a story-understanding process in which two mechanisms found in everyday comprehension are missing: conceiving sequences (chunking categories in time as a higher-order categorization) and coordinating across modalities (e.g., relating the sound of a word and the image of its meaning). On this basis, we can readily identify isomorphisms between dream phenomenology and neurophysiology, and explain the function of dreaming as facilitating future coordination of sequential, cross-modal categorization (i.e., REM sleep lowers activation thresholds, "unlearning"). C1 NASA, Ames Res Ctr, Computat Sci Div, Moffett Field, CA 94035 USA. RP Clancey, WJ (reprint author), NASA, Ames Res Ctr, Computat Sci Div, MIS 269-3, Moffett Field, CA 94035 USA. NR 9 TC 3 Z9 3 U1 0 U2 4 PU CAMBRIDGE UNIV PRESS PI PORT CHESTER PA 110 MIDLAND AVE, PORT CHESTER, NY 10573-9863 USA SN 0140-525X J9 BEHAV BRAIN SCI JI Behav. Brain Sci. PD DEC PY 2000 VL 23 IS 6 BP 919 EP + DI 10.1017/S0140525X00334021 PG 43 WC Psychology, Biological; Behavioral Sciences; Neurosciences SC Psychology; Behavioral Sciences; Neurosciences & Neurology GA 456VF UT WOS:000170102400018 ER PT J AU Stephens, GL Ellingson, RG Vitko, J Bolton, W Tooman, TP Valero, FPJ Minnis, P Pilewskie, P Phipps, GS Sekelsky, S Carswell, JR Miller, SD Benedetti, A McCoy, RB McCoy, RF Lederbuhr, A Bambha, R AF Stephens, GL Ellingson, RG Vitko, J Bolton, W Tooman, TP Valero, FPJ Minnis, P Pilewskie, P Phipps, GS Sekelsky, S Carswell, JR Miller, SD Benedetti, A McCoy, RB McCoy, RF Lederbuhr, A Bambha, R TI The Department of Energy's Atmospheric Radiation Measurement (ARM) Unmanned Aerospace Vehicle (UAV) program SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID SHORTWAVE EXPERIMENT ARESE; CLOUD; PARAMETERIZATION; ABSORPTION; RETRIEVAL; AIRCRAFT; SUCCESS AB The U.S. Department of Energy has established an unmanned aerospace vehicle (UAV) measurement program. The purpose of this paper is to describe the evolution of the program since its inception, review the progress of the program, summarize the measurement capabilities developed under the program, illustrate key results from the various UAV campaigns carried out to date, and provide a sense of the future direction of the program. The Atmospheric Radiation Measurement (ARM)-UAV program has demonstrated how measurements from unmanned aircraft platforms operating under the various constraints imposed by different science experiments can contribute to our understanding of cloud and radiative processes. The program was first introduced in 1991 and has evolved in the form of four phases of activity each culminating in one or more flight campaigns. A total of 8 flight campaigns produced over 140 h of science flights using three different UAV platforms. The UAV platforms and their capabilities are described as are the various phases of the program development. Examples of data collected from various campaigns highlight the powerful nature of the observing system developed under the auspices of the ARM-UAV program and confirm the viability of the UAV platform for the kinds of research of interest to ARM and the clouds and radiation community as a whole. The specific examples include applications of the data in the study of radiative transfer through clouds, the evaluation of cloud parameterizations, and the development and evaluation of cloud remote sensing methods. A number of notable and novel achievements of the program are also highlighted. C1 Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. Sandia Natl Labs, Livermore, CA USA. Scripps Inst Oceanog, San Diego, CA USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23665 USA. NASA, Ames Res Ctr, Sunnyvale, CA USA. Sandia Natl Labs, Albuquerque, NM 87185 USA. Univ Massachusetts, Amherst, MA 01003 USA. Univ Calif Lawrence Livermore Natl Lab, Livermore, CA USA. Univ Calif Davis, Crocker Nucl Lab, Davis, CA 95616 USA. RP Stephens, GL (reprint author), Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 27 TC 21 Z9 21 U1 1 U2 7 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 DEC PY 2000 VL 81 IS 12 BP 2915 EP 2937 DI 10.1175/1520-0477(2000)081<2915:TDOESA>2.3.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 379ZG UT WOS:000165672600001 ER PT J AU Levenspiel, O Fitzgerald, TJ Pettit, D AF Levenspiel, O Fitzgerald, TJ Pettit, D TI Earth's atmosphere before the age of dinosaurs SO CHEMICAL INNOVATION LA English DT Editorial Material C1 Oregon State Univ, Corvallis, OR 97331 USA. TRW Co Inc, Space Technol Div, Redondo Beach, CA 90278 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Levenspiel, O (reprint author), Oregon State Univ, Corvallis, OR 97331 USA. NR 20 TC 0 Z9 0 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1527-4799 J9 CHEM INNOV JI Chem. Innov. PD DEC PY 2000 VL 30 IS 12 BP 50 EP 55 PG 6 WC Chemistry, Applied SC Chemistry GA 380LA UT WOS:000165702300009 ER PT J AU Lundell, J Chaban, GM Gerber, RB AF Lundell, J Chaban, GM Gerber, RB TI Combined ab initio and anharmonic vibrational spectroscopy calculations for rare gas containing fluorohydrides, HRgF SO CHEMICAL PHYSICS LETTERS LA English DT Article ID RELATIVISTIC EFFECTIVE POTENTIALS; SPIN-ORBIT OPERATORS; SELF-CONSISTENT-FIELD; WAVE-FUNCTIONS; XE; MOLECULES; KR AB MP2 and CCSD(T) calculations are used to analyse the structures and vibrational spectra of HRgF molecules, where the rare gas atom is He, Ne, Ar, Rr, Xe or Rn. We extend the analysis of the vibrational spectra of these molecules to include anharmonic corrections for the most likely candidates for experimental detection, i.e., HArF, HKrF, HXeF, and their deuterated isotopomers. The anharmonic correlation-corrected vibrational self-consistent-field (CC-VSCF) calculations are used for this, and fundamental, overtone and combination frequencies and their absorption intensities are computed. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Helsinki, Phys Chem Lab, FIN-00014 Helsinki, Finland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. Hebrew Univ Jerusalem, Dept Phys Chem, IL-91904 Jerusalem, Israel. Hebrew Univ Jerusalem, Fritz Haber Res Ctr Mol Dynam, IL-91904 Jerusalem, Israel. RP Lundell, J (reprint author), Univ Helsinki, Phys Chem Lab, POB 55,AI Virtasen Aukio 1, FIN-00014 Helsinki, Finland. NR 33 TC 92 Z9 93 U1 0 U2 3 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 DEC 1 PY 2000 VL 331 IS 2-4 BP 308 EP 316 DI 10.1016/S0009-2614(00)01180-5 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 380UG UT WOS:000165721400029 ER PT J AU Mount, DM Netanyahu, NS Silverman, R Wu, AY AF Mount, DM Netanyahu, NS Silverman, R Wu, AY TI Chromatic nearest neighbor searching: A query sensitive approach SO COMPUTATIONAL GEOMETRY-THEORY AND APPLICATIONS LA English DT Article DE chromatic nearest neighbors; classification algorithms; pattern recognition; multidimensional searching; BBD trees; branch-and-bound search; query sensitive analysis ID CLOSEST-POINT QUERIES; ALGORITHM; DIMENSIONS AB The nearest neighbor problem is that of preprocessing a set P of n data points in R-d so that given any query point q, the closest point in P to q can be determined efficiently. In the chromatic nearest neighbor problem, each point of P is assigned a color, and the problem is to determine the color of the nearest point to the query point. More generally, given k greater than or equal to 1, the problem is to determine the color occurring most frequently among the k nearest neighbors. The chromatic version of the nearest neighbor problem is used in many applications in pattern recognition and learning. In this paper we present a simple algorithm for solving the chromatic k nearest neighbor problem. We provide a query sensitive analysis, which shows that if the color classes form spatially well separated clusters (as often happens in practice), then queries can be answered quite efficiently. We also allow the user to specify an error bound epsilon greater than or equal to 0, and consider the same problem in the context of approximate nearest neighbor searching. We present empirical evidence that for well clustered data sets, this approach leads to significant improvements in efficiency. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Maryland, Dept Comp Sci, College Pk, MD 20742 USA. Univ Maryland, Inst Adv Comp Studies, College Pk, MD 20742 USA. Bar Ilan Univ, Dept Math & Comp Sci, IL-52900 Ramat Gan, Israel. Univ Maryland, Ctr Automat Res, College Pk, MD 20742 USA. American Univ, Dept Comp Sci & Informat Syst, Washington, DC 20016 USA. NASA, Ctr Excellence Space Data & Informat Sci, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Mount, DM (reprint author), Univ Maryland, Dept Comp Sci, College Pk, MD 20742 USA. NR 35 TC 7 Z9 7 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0925-7721 J9 COMP GEOM-THEOR APPL JI Comput. Geom.-Theory Appl. PD DEC PY 2000 VL 17 IS 3-4 BP 97 EP 119 DI 10.1016/S0925-7721(00)00021-3 PG 23 WC Mathematics, Applied; Mathematics SC Mathematics GA 389CH UT WOS:000166220700001 ER PT J AU Beck, G Djordjevic, B Halacka, KM Hamilton, D Johannesen, J McGinnis, P Melton, M Rasbury, J Billica, R McDonald, V AF Beck, G Djordjevic, B Halacka, KM Hamilton, D Johannesen, J McGinnis, P Melton, M Rasbury, J Billica, R McDonald, V TI Evaluation of critical care monitors using satellite network for space and terrestrial applications SO CRITICAL CARE MEDICINE LA English DT Meeting Abstract C1 Wyle Labs, Life Sci Syst & Serv, Houston, TX USA. Univ Alberta, Sch Med, Edmonton, AB, Canada. Case Western Reserve Univ, Cleveland, OH 44106 USA. NASA, Lyndon B Johnson Space Ctr, Flight Med Clin, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0090-3493 J9 CRIT CARE MED JI Crit. Care Med. PD DEC PY 2000 VL 28 IS 12 SU S MA 118 BP A62 EP A62 PG 1 WC Critical Care Medicine SC General & Internal Medicine GA 388ZD UT WOS:000166212200119 ER PT J AU Moody, SA Golden, C AF Moody, SA Golden, C TI Developmental biology research in space: Issues and directions in the era of the International Space Station - Notes from the September 1999 meeting of the International Space Life Sciences Working Group in Woods Hole, Massachusetts SO DEVELOPMENTAL BIOLOGY LA English DT Review C1 George Washington Univ, Med Ctr, Dept Anat & Cell Biol, Washington, DC 20037 USA. NASA, Ames Res Ctr, Fundamental Biol Program, Moffett Field, CA 94035 USA. RP Moody, SA (reprint author), George Washington Univ, Med Ctr, Dept Anat & Cell Biol, 2300 I Eye St NW, Washington, DC 20037 USA. OI Moody, Sally/0000-0003-4192-1087 NR 3 TC 12 Z9 12 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0012-1606 J9 DEV BIOL JI Dev. Biol. PD DEC 1 PY 2000 VL 228 IS 1 BP 1 EP 5 DI 10.1006/dbio.2000.9907 PG 5 WC Developmental Biology SC Developmental Biology GA 380LC UT WOS:000165702500001 PM 11087621 ER PT J AU Blandino, JJ Goodwin, DG Garner, CE AF Blandino, JJ Goodwin, DG Garner, CE TI Low energy sputter yields for diamond, carbon-carbon composite, and molybdenum subject to xenon ion bombardment SO DIAMOND AND RELATED MATERIALS LA English DT Article DE diamond; sputtering; polycrystalline; single crystal ID FILMS; PLASMA AB Sputter yields have been measured for polycrystalline diamond, single crystal diamond, a carbon-carbon composite, and molybdenum subject to xenon ion bombardment. The tests were performed using a 3-cm Kaufman ion source to produce incident ions with energy in the range of 150-750 eV and a profilometry-based technique to measure the amount of sputtered material. The yields increased monotonically with energy with values ranging from 0.16 at 150 eV to 0.80 at 750 eV for the molybdenum and 0.06 to 0.14 for the carbon-carbon. At 150 eV the yield for both diamond samples was 0.07 and at 750 eV 0.19 and 0.17 for the CVD and single crystal diamond, respectively. A number of experimental factors affecting sputter yield measurements using this technique are described. (C) 2000 Elsevier Science B.V. All rights reserved. C1 CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Blandino, JJ (reprint author), CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. NR 23 TC 18 Z9 18 U1 3 U2 12 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0925-9635 J9 DIAM RELAT MATER JI Diam. Relat. Mat. PD DEC PY 2000 VL 9 IS 12 BP 1992 EP 2001 DI 10.1016/S0925-9635(00)00350-2 PG 10 WC Materials Science, Multidisciplinary SC Materials Science GA 377ZR UT WOS:000165556900008 ER PT J AU Emmett, R Llanso, R Newton, J Thom, R Hornberger, M Morgan, C Levings, C Copping, A Fishman, P AF Emmett, R Llanso, R Newton, J Thom, R Hornberger, M Morgan, C Levings, C Copping, A Fishman, P TI Geographic signatures of North American West Coast estuaries SO ESTUARIES LA English DT Review ID SAN-FRANCISCO BAY; COLUMBIA RIVER ESTUARY; CLAM POTAMOCORBULA-AMURENSIS; PUGET-SOUND; REMARKABLE INVASION; PACIFIC-NORTHWEST; STANDING STOCK; SALT MARSHES; CALIFORNIA; WASHINGTON AB West Coast estuaries are geologically young and composed of a variety of geomorphological types. These estuaries range from large fjords to shallow lagoons; from large to low freshwater flows. Natural hazards include El Ninos, strong Pacific storms, and active tectonic activity. West Coast estuaries support a wide range of living resources: five salmon species, harvestable shellfish, waterfowl and marine birds, marine mammals, and a variety of algae and plants. Although populations of many of these living resources have declined (salmonids), others have increased (marine mammals). West Coast estuaries are also centers of commerce and increasingly large shipping traffic. The West Coast human population is rising faster than most other areas of the U.S. and Canada, and is distributed heavily in southern California, the San Francisco Bay area, around Puget Sound, and the Fraser River estuary. While water pollution is a problem in many of the urbanized estuaries, most estuaries do not suffer from poor water quality. Primary estuarine problems include habitat alterations, degradation, and loss; diverted freshwater flows; marine sediment contamination; and exotic species introductions. The growing West Coast economy and population are in part related to the quality of life, which is dependent on the use and enjoyment of abundant coastal natural resources. C1 NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Newport, OR 97330 USA. Washington Dept Ecol, Olympia, WA 98504 USA. Pacific NW Natl Lab, Battelle Marine Sci Lab, Sequim, WA 98382, Australia. US Geol Survey, Menlo Pk, CA 94025 USA. Oregon State Univ, Cooperat Inst Marine Resource Studies, Newport, OR 97365 USA. Canadian Dept Fisheries Oceans, Pacific Environm Sci Ctr, N Vancouver, BC V7H 1V2, Canada. Univ Washington, Washington Sea Grant Program, Seattle, WA 98105 USA. Fishman Environm Serv, Portland, OR 97209 USA. RP Emmett, R (reprint author), NOAA, Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, 2030 S Marine Sci Dr, Newport, OR 97330 USA. EM Robert.Emmett@noaa.gov NR 169 TC 75 Z9 77 U1 3 U2 35 PU ESTUARINE RESEARCH FEDERATION PI PORT REPUBLIC PA 2018 DAFFODIL, PO BOX 510, PORT REPUBLIC, MD 20676 USA SN 0160-8347 J9 ESTUARIES JI Estuaries PD DEC PY 2000 VL 23 IS 6 BP 765 EP 792 DI 10.2307/1352998 PG 28 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 400BF UT WOS:000166848200002 ER PT J AU Linde, C AF Linde, C TI The acquisition of a speaker by a story: How history becomes memory and identity SO ETHOS LA English DT Article AB This paper investigates narrative induction as one central means by which institutions acquire new members, and new members acquire a new identity. Narrative induction is the process by which people take on an existing set of stories as relevant to the shaping of their own story. Nonparticipant narratives (narratives told by speakers not present at the events narrated) are used to reproduce collective memory and induct new participants into this memory. The process has three parts: how a person comes to take on someone else's story as centrally relevant to their own; how a person comes to tell their own story in a way shaped by the stories of others, and how a person's story may come to be told and heard by others within an institution as an instance of a normative pattern. This paper demonstrates each phase of the process, using as data an ethnographic study of a major American insurance company. C1 NASA, Ames Res Lab, Moffett Field, CA USA. RP Linde, C (reprint author), NASA, Ames Res Lab, Moffett Field, CA USA. NR 28 TC 15 Z9 15 U1 0 U2 0 PU AMER ANTHROPOLOGICAL ASSOC PI ARLINGTON PA 4350 NORTH FAIRFAX DRIVE SUITE 640, ARLINGTON, VA 22203 USA SN 0091-2131 J9 ETHOS JI Ethos PD DEC PY 2000 VL 28 IS 4 BP 608 EP 632 DI 10.1525/eth.2000.28.4.608 PG 25 WC Anthropology; Psychology, Multidisciplinary SC Anthropology; Psychology GA 473GX UT WOS:000171033100007 ER PT J AU Wu, MW Ning, CZ AF Wu, MW Ning, CZ TI A novel mechanism for spin dephasing due to spin-conserving scatterings SO EUROPEAN PHYSICAL JOURNAL B LA English DT Article ID SEMICONDUCTOR QUANTUM-WELLS; EXCITONIC FARADAY-ROTATION; CYCLOTRON-RESONANCE; RELAXATION; COHERENT; GAAS; HETEROSTRUCTURES; DYNAMICS; BAND AB A new spin dephasing mechanism is proposed for semiconductors with carrier momentum-dependent transition energies (inhomogeneous broadening) between spin states. In the presence of this: inhomogeneous broadening of the spin transitions, spin-conserving (SC) scatterings lead to irreversible spill dephasing in a complete analogy to the optical dephasing of inhomogeneously broadened optical transitions. This phenomenon is demonstrated for the case when the g-factor becomes electron-energy dependent. C1 Univ Calif Santa Barbara, Dept Chem, Santa Barbara, CA 93106 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Wu, MW (reprint author), Univ Calif Santa Barbara, Dept Chem, Santa Barbara, CA 93106 USA. RI Ning, C. Z./D-4699-2009 OI Ning, C. Z./0000-0003-4583-8889 NR 42 TC 85 Z9 87 U1 0 U2 5 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1434-6028 J9 EUR PHYS J B JI Eur. Phys. J. B PD DEC PY 2000 VL 18 IS 3 BP 373 EP 376 DI 10.1007/s100510070021 PG 4 WC Physics, Condensed Matter SC Physics GA 389DY UT WOS:000166224400001 ER PT J AU Thomas-Keprta, KL Bazylinski, DA Kirschvink, JL Clemett, SJ McKay, DS Wentworth, SJ Vali, H Gibson, EK Romanek, CS AF Thomas-Keprta, KL Bazylinski, DA Kirschvink, JL Clemett, SJ McKay, DS Wentworth, SJ Vali, H Gibson, EK Romanek, CS TI Elongated prismatic magnetite crystals in ALH84001 carbonate globules: Potential Martian magnetofossils SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Review ID DEEP-SEA SEDIMENTS; DOMAIN TITANOMAGNETITE PARTICLES; TRANSMISSION ELECTRON-MICROSCOPE; ULTRAFINE-GRAINED MAGNETITE; NORTHERN APPALACHIAN BASIN; MAGNETOTACTIC BACTERIA; BIOGENIC MAGNETITE; METEORITE ALH84001; SINGLE-DOMAIN; REMANENT MAGNETIZATION AB Using transmission electron microscopy (TEM), we have analyzed magnetite (Fe3O4) crystals acid-extracted from carbonate globules in Martian meteorite ALH84001. We studied 594 magnetites from ALH84001 and grouped them into three populations on the basis of morphology: 389 were irregularly shaped, 164 were elongated prisms, and 41 were whisker-like. As a possible terrestrial analog for the ALH84001 elongated prisms, we compared these magnetites with those produced by the terrestrial magnetotactic bacteria strain MV-1. By TEM again, we examined 206 magnetites recovered from strain MV-1 cells. Natural (Darwinian) selection in terrestrial magnetotactic bacteria appears to have resulted in the formation of intracellular magnetite crystals having the physical and chemical properties that optimize their magnetic moment. In this study, we describe six properties of magnetite produced by biologically controlled mechanisms (e.g., magnetotactic bacteria), properties that, collectively, are not observed in any known population of inorganic magnetites. These criteria can be used to distinguish one of the modes of origin for magnetites from samples with complex or unknown histories. Of the ALH84001 magnetites that we have examined, the elongated prismatic magnetite particles (similar to 27% of the total) are indistinguishable from the MV-1 magnetites in five of these six characteristics observed for biogenically controlled mineralization of magnetite crystals. Copyright (C) 2000 Elsevier Science Ltd. C1 Lockheed Martin, Houston, TX 77058 USA. Iowa State Univ Sci & Technol, Dept Microbiol, Ames, IA 50011 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. McGill Univ, Dept Earth & Planetary Sci, Montreal, PQ H3A 2A7, Canada. Univ Georgia, Savannah River Ecol Lab, Aiken, SC 29802 USA. RP Lockheed Martin, 2400 NASA Rd 1,Mail Code C23, Houston, TX 77058 USA. EM kthomas@ems.jsc.nasa.gov RI Vali, Hojatollah/F-3511-2012 OI Vali, Hojatollah/0000-0003-3464-9943 NR 207 TC 173 Z9 182 U1 4 U2 28 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 DEC PY 2000 VL 64 IS 23 BP 4049 EP 4081 DI 10.1016/S0016-7037(00)00481-6 PG 33 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 376FP UT WOS:000165447800010 PM 11543573 ER PT J AU Hide, R Boggs, DH Dickey, JO AF Hide, R Boggs, DH Dickey, JO TI Angular momentum fluctuations within the Earth's liquid core and torsional oscillations of the core-mantle system SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE Earth's fluid core; Earth rotation fluctuations; geodynamo; magnetohydrodynamics ID GEOMAGNETIC SECULAR VARIATION; TOPOGRAPHIC TORQUE; GEOSTROPHIC FLOW; INNER-CORE; OUTER-CORE; ROTATION; SURFACE; FLUID; MOTIONS; LENGTH AB Non-steady differential rotation is one of the main characteristics of the buoyancy-driven flow within the Earth's liquid metallic outer core that generates the main geomagnetic field by magnetohydrodynamic (MHD) dynamo action. Concomitant fluctuations in angular momentum transfer both within the core and between the core and the overlying 'solid' mantle are investigated by assuming that average departures from 'isorotation' on coaxial cylindrical surfaces are negligibly small. The interval of time covered by the analysis is the 15 decades from 1840 to 1990, for which requisite determinations are available of decadal fluctuations of the length of the day (LOD) and also of how velocities just below the core-mantle boundary (CMB), as inferred from geomagnetic secular variation (GSV) data. Core angular momentum (CAM) fluctuations are most pronounced in the mid-latitudes, where they are generally out of phase with those occurring in equatorial regions. They are roughly in phase with decadal LOD fluctuations, especially after about 1870, with a dominant variability period of approximately 65 years, in keeping with previous analyses based on GSV and/or LOD data. The largest positive correlations (0.8 when data before 1867.5 are excluded) are found in the mid-latitudes, with a maximum at zero lag and with secondary peaks at 67 years and at -64 years, again implying a mode of approximately 65 years. Propagation of CAM anomalies from the equatorial to polar regions is evident in both the time-latitude dependence of CAM and its latitudinal correlation with length of day fluctuations. Future work on excitation mechanisms should establish the connection, if any, between the dominant timescale of approximately 65 years seen in the data and the gravest of the theoretically possible subseismic modes of torsional MHD oscillations of the core. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Oxford, Clarendon Lab, Phys Dept Atmospher Ocean & Planetary Phys, Oxford OX2 3PU, England. RP Hide, R (reprint author), Univ London Imperial Coll Sci Technol & Med, Dept Math, 180 Queens Gate, London SW7 2BZ, England. NR 58 TC 35 Z9 36 U1 0 U2 5 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD DEC PY 2000 VL 143 IS 3 BP 777 EP 786 DI 10.1046/j.0956-540X.2000.01283.x PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 378VB UT WOS:000165604500020 ER PT J AU Richardson, IG Berdichevsky, D Desch, MD Farrugia, CJ AF Richardson, IG Berdichevsky, D Desch, MD Farrugia, CJ TI Solar-cycle variation of low density solar wind during more than three solar cycles SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The May, 1999 low density (< 1 cm(-3)) solar wind interval is one of a series of intervals of low density solar wind which have been detected since in-situ, near-Earth observations began. Examining the NSSDC OMNI database since 1965, covering solar Cycles 20-23, we show that such intervals, which are also periods of unusually low mass flux and low dynamic pressure, occur most frequently around sunspot maximum and are rarer at solar minimum. The occurrence rate of low-density plasma may be higher in weaker sunspot cycles (Cycle 20 and the current Cycle 23). Around two-thirds of periods with densities less than or equal to 1 cm(-3) are associated with transient solar wind structures, in particular with ejecta and post-shock flows. The majority of other events are associated with corotating streams. The May 1999 event is unusual because it is not associated with an ejecta or stream. A similar period was observed in July August 1979. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ New Hampshire, Durham, NH 03824 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. R ITSS, Lanham, MD USA. RP Richardson, IG (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. OI Richardson, Ian/0000-0002-3855-3634 NR 10 TC 37 Z9 37 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2000 VL 27 IS 23 BP 3761 EP 3764 DI 10.1029/2000GL000077 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 379MQ UT WOS:000165646700001 ER PT J AU Usmanov, AV Goldstein, ML Farrell, WM AF Usmanov, AV Goldstein, ML Farrell, WM TI A view of the inner heliosphere during the may 10-11, 1999 - Low density anomaly SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND AB On May 10 and 11, 1999, near-Earth spacecraft observed the solar wind density drop to below 0.1 particles cm(-3). Using those data, we have mapped solar wind parameters back to the Sun from 1 AU using two techniques. The first assumed constant-velocity trajectories plus corotation, while the second employed MI-ID-derived magnetofluid parameters. This inverse tracing creates a view of the inner heliosphere useful for identifying the source location on the Sun of the density anomaly. We compare the two methods and show that the source location of the anomaly predicted by MHD is mapped similar to 20 degrees eastward of the constant-velocity result. The coronal magnetic field maps indicate that the low density event occurred as the polar coronal magnetic field began reversing. We suggest that the event was initiated by a latitudinal excursion of the low velocity heliospheric current sheet toward the helioequator. The emergence of this dow flow into the preexisting faster wind produced strong rarefaction and anomalously low densities. C1 St Petersburg State Univ, Inst Phys, St Petersburg 198904, Russia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Usmanov, AV (reprint author), St Petersburg State Univ, Inst Phys, St Petersburg 198904, Russia. RI Goldstein, Melvyn/B-1724-2008; Usmanov, Arcadi/A-9860-2013; Farrell, William/I-4865-2013 NR 7 TC 16 Z9 16 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2000 VL 27 IS 23 BP 3765 EP 3768 DI 10.1029/2000GL000082 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 379MQ UT WOS:000165646700002 ER PT J AU Crooker, NU Shodhan, S Gosling, JT Simmerer, J Lepping, RP Steinberg, JT Kahler, SW AF Crooker, NU Shodhan, S Gosling, JT Simmerer, J Lepping, RP Steinberg, JT Kahler, SW TI Density extremes in the solar wind SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CORONAL MASS EJECTIONS; INTER-PLANETARY; MAGNETIC CLOUDS; FLUCTUATIONS; EVENTS; 1-AU; FLUX AB The largest density variations in the solar wind occur near the streamer belt, where frequently they are associated with interplanetary coronal mass ejections (ICMEs). They tend to be embedded in larger-scale regions of high pressure: high densities in ICME sheaths and corotating interaction regions and low densities in structures with distinctive, high-magnetic-pressure profiles, sometimes within ICMEs. On average, however, ICME densities are similar to ambient-wind densities. I;or a set of 34 ICMEs identified in Wind data as magnetic clouds, the average density was 11 cm(-3) in both the clouds and all slow wind during the same period. A set of low-density structures observed earlier by ISEE 3 recurred for three solar rotations, possibly owing to recurrence of the streamer belt itself, with its frequent transient outflows. Density averages less than 1 cm(-3) show a possible solar cycle variation which peaks 1-2 years prior to the peak of ICME signatures. C1 Boston Univ, Ctr Space Phys, Boston, MA 02215 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. USAF, Res Lab, Space Vehicles Directorate, Hanscom AFB, MA USA. RP Crooker, NU (reprint author), Boston Univ, Ctr Space Phys, Boston, MA 02215 USA. NR 28 TC 26 Z9 26 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2000 VL 27 IS 23 BP 3769 EP 3772 DI 10.1029/2000GL003788 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 379MQ UT WOS:000165646700003 ER PT J AU Farrugia, CJ Singer, HJ Evans, D Berdichevsky, D Scudder, JD Ogilvie, KW Fitzenreiter, RJ Russell, CT AF Farrugia, CJ Singer, HJ Evans, D Berdichevsky, D Scudder, JD Ogilvie, KW Fitzenreiter, RJ Russell, CT TI Response of the equatorial and polar magnetosphere to the very tenuous solar wind on May 11, 1999 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RAIN; PRECIPITATION AB We examine effects in the equatorial and polar magnetosphere during 9-13 May, 1999. Earth's field at geostationary orbit became closely dipolar for similar to 16 hours when solar wind densities n(sw) were < 1 cm(-3) Electron precipitation in the northern polar cap intensified as n(sw) decreased, with significant fluxes up to similar to 15 keV energy on May 11. The simultaneous precipitation void in the southern polar cap implies a very pronounced north-south asymmetry, also reflected in the hemispherical power deposition. With an intense and collimated strahl, these observations support the ideas of Fairfield and Scudder [1985] on the preferential entry of the strahl into the northern hemisphere under the observed IMF away sector as a source of the north-south precipitation asymmetry. The polar rain north-south asymmetry argues against an ejecta source for the solar wind drop-out. The temporal profiles of solar wind parameters were very asymmetric with respect to the time of minimum n(sw), and strong compressions and substorm activity prevailed as n(sw) recovered. C1 Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA. NOAA, Space Environm Ctr, Boulder, CO USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon ITSS, Lanham, MD USA. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA. RP Farrugia, CJ (reprint author), Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA. RI Scudder, Jack/D-8417-2013; OI Scudder, Jack/0000-0001-7975-5630; Russell, Christopher/0000-0003-1639-8298 NR 8 TC 21 Z9 21 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2000 VL 27 IS 23 BP 3773 EP 3776 DI 10.1029/2000GL003800 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 379MQ UT WOS:000165646700004 ER PT J AU Kaufman, YJ Holben, BN Tanre, D Slutsker, I Smirnov, A Eck, TF AF Kaufman, YJ Holben, BN Tanre, D Slutsker, I Smirnov, A Eck, TF TI Will aerosol measurements from Terra and Aqua polar orbiting satellites represent the daily aerosol abundance and properties? SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MODIS AIRBORNE SIMULATOR; TROPOSPHERIC AEROSOL; RETRIEVAL; OCEAN; LAND AB The Terra and Aqua missions will help quantify aerosol radiative forcing of climate by providing innovative measurements of the aerosol daily spatial distribution and identifying dust, smoke and regional pollution. However, these measurements are acquired at specific times of the day. To what extent can such measurements represent the daily average aerosol forcing of climate? We answer this question using 7 years of data from the Aerosol Robotic Network (AERONET) of 50-70 global ground-based instruments. AERONET measures the aerosol spectral optical thickness and the total precipitable water vapor every 15 minutes throughout the day. With a data set of 1/2 million measurements, AERONET demonstrates that Terra and Aqua aerosol measurements can represent the annual average value within 2% error. This excellent Terra representation of the daily average optical thickness is independent of the particle size or range of the optical thickness. This finding should facilitate ingest of satellite aerosol measurements in models that calculate radiative forcing and predict climate change. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Sci & Tech Lille Flandres Artois, CNRS, Opt Atmospher Lab, Villeneuve Dascq, France. Sci Syst & Appl Inc, Lanham, MD 20706 USA. Raytheon ITSS, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kaufman, YJ (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. RI Smirnov, Alexander/C-2121-2009; ECK, THOMAS/D-7407-2012 OI Smirnov, Alexander/0000-0002-8208-1304; NR 16 TC 91 Z9 95 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2000 VL 27 IS 23 BP 3861 EP 3864 DI 10.1029/2000GL011968 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 379MQ UT WOS:000165646700026 ER PT J AU Callis, LB Natarajan, M Lambeth, JD AF Callis, LB Natarajan, M Lambeth, JD TI Calculated upper stratospheric effects of solar UV flux and NOy variations during the 11-year solar cycle SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE ATMOSPHERE; SHORT-TERM; LONG-TERM; ULTRAVIOLET VARIATIONS; OZONE; MODEL; VARIABILITY; ELECTRONS; NIMBUS-7 AB Model derived sensitivities of O-3 near 40 km to solar UV flux changes (11-year and 27-day) fall within the range 0.36 - 0.55 with S-11y approximate toS(27d). These sensitivities derived from observations have been reported to be 0.91 and 0.39 - 0.46, respectively. This discrepancy appears to be due to long-term (2-10 years) fluctuations in stratospheric NO2 in the 1980s. Such fluctuations, if not taken into account in the analysis of the date, could lead to high values of the sensitivity for the 11-year activity cycle but not for the 27-day solar rotation period. Simulations accounting for such effects suggest a consistency between theoretical values of S-11y and those derived from data if NO2 effects are included. The appropriate values are approximately 0.48, a value similar to published model calculations and results from the analysis of data from the 27-day solar rotation period. Verification of this suggestion awaits an NO2 data, base of sufficient quality and length to permit solar-cycle trend calculations to be made. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Sci Applicat Int Corp, Hampton, VA 23666 USA. RP Callis, LB (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, Mail Stop 401B, Hampton, VA 23681 USA. NR 27 TC 15 Z9 15 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD DEC 1 PY 2000 VL 27 IS 23 BP 3869 EP 3872 DI 10.1029/2000GL011622 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 379MQ UT WOS:000165646700028 ER PT J AU Del Grosso, SJ Parton, WJ Mosier, AR Ojima, DS Potter, CS Borken, W Brumme, R Butterbach-Bahl, K Crill, PM Dobbie, K Smith, KA AF Del Grosso, SJ Parton, WJ Mosier, AR Ojima, DS Potter, CS Borken, W Brumme, R Butterbach-Bahl, K Crill, PM Dobbie, K Smith, KA TI General CH4 oxidation model and comparisons of CH4 oxidation in natural and managed systems SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID COLORADO SHORTGRASS STEPPE; LAND-USE CHANGE; METHANE OXIDATION; TEMPERATE FOREST; NITROUS-OXIDE; N AVAILABILITY; N2O FLUXES; SOILS; CONSUMPTION; MOISTURE AB Fluxes of methane from field observations of native and cropped grassland soils in Colorado and Nebraska were used to model CH4 oxidation as a function of soil water content, temperature, porosity, and field capacity (FC). A beta function is used to characterize the effect of soil water on the physical limitation of gas diffusivity when water is high and biological limitation when water is low. Optimum soil volumetric water content (W-opt) increases with FC. The site specific maximum CH4 oxidation rate (CH4max) varies directly with soil gas diffusivity (D) as a function of soil bulk density and FC. Although soil water content and physical pro are the primary controls on CH4 uptake, the potential for soil temperature to affect CH4 uptake rates increases as soils become less limited by gas diffusivity. Daily CH4 oxidation rate is calculated as the product of CH4max, the normalized (0-100%) beta function to account for water effects, a temperature multiplier, and an adjustment factor to account for the effects of agriculture on methane flux. The model developed with grassland soils also worked well in coniferous and tropical forest soils. However, soil gas diffusivity as a function of field capacity, and bulk density did not reliably predict maximum CH4 oxidation rates in deciduous forest soils, so a submodel for these systems was developed assuming that CH4max is a function of mineral soil bulk density. The overall model performed well with the data used for model development (r(2) = 0.76) and with independent data from grasslands, cultivated lands, and coniferous, deciduous, and tropical forests (r(2) = 0.73, mean error < 6%). C1 Colorado State Univ, Nat Resource Ecol Lab, Ft Collins, CO 80523 USA. Univ Gottingen, Inst Soil Sci & Forest Nutr, D-37077 Gottingen, Germany. Inst Atmospher Environm Res, D-82467 Garmisch Partenkirchen, Germany. Univ New Hampshire, Inst Study Earth Oceans & Space, Durham, NH 03824 USA. Univ Edinburgh, Inst Ecol & Resource Management, Edinburgh EH9 3JG, Midlothian, Scotland. USDA ARS, Ft Collins, CO 80523 USA. NASA, Ames Res Ctr, Johnson Controls World Services Inc, Moffett Field, CA 94035 USA. RP Del Grosso, SJ (reprint author), Colorado State Univ, Nat Resource Ecol Lab, Ft Collins, CO 80523 USA. EM delgro@nrel.colostate.edu; billp@nrel.colostate.edu; amosier@lamar.colostate.edu; dennis@nrel.colostate.edu; cpotter@gaia.arc.nasa.gov; rbrumme@ufbwserver.uni-forst.gwdg.de; butterbach@ifu.fhg.de; patrick.crill@unh.edu; karen.dobbie@ed.ac.uk; k.a.smith@ed.ac.uk RI Garmisch-Pa, Ifu/H-9902-2014; Ojima, Dennis/C-5272-2016; Butterbach-Bahl, Klaus/A-8081-2013; OI Crill, Patrick/0000-0003-1110-3059 NR 41 TC 100 Z9 102 U1 5 U2 41 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD DEC PY 2000 VL 14 IS 4 BP 999 EP 1019 PG 21 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA 391EK UT WOS:000166341000002 ER PT J AU Bogner, JE Sass, RL Walter, BP AF Bogner, JE Sass, RL Walter, BP TI Model comparisons of methane oxidation across a management gradient: Wetlands, rice production systems, and landfill SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID ATMOSPHERIC METHANE; TEMPORAL VARIATIONS; PADDY SOILS; EMISSIONS; VEGETATION; PEATLANDS; RHIZOSPHERE; FIELDS; FLUX AB Through model experiments we quantitatively examined fractional methane oxidation and net methane emissions using three model systems which encompass a management gradient from pristine (wetlands) to managed (rice production) to highly engineered (landfills). Fractional methane oxidation is rarely determined in situ; thus our goal was to cross-compare modeling results and major drivers to field and laboratory data for this important parameter in both pristine and managed systems. In the models, management factors are typically introduced as combinations of theoretical relationships, empirical functions, or scaling factors which drive net emissions through forcing of water table variations, availability of degradable organic carbon substrates, input and cycling of major nutrients, variability in plant communities, physical properties for gaseous transport, and indigenous capacity of soils for methane oxidation. The net methane emission and fractional oxidation vary by orders of magnitude within and among the three model systems, yet each model was quite consistent in its predictive ability. This study lays the groundwork for a more unified, modular approach to modeling methane emissions from soil sources where both natural (climatic and ecological) and anthropogenic factors are important drivers. C1 Landfills Inc, Wheaton, IL 60187 USA. Univ Illinois, Dept Earth & Environm Sci, Chicago, IL USA. Rice Univ, Dept Ecol & Evolutionary Biol, Houston, TX 77251 USA. Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Bogner, JE (reprint author), Landfills Inc, 1144 N President St, Wheaton, IL 60187 USA. NR 51 TC 11 Z9 12 U1 2 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD DEC PY 2000 VL 14 IS 4 BP 1021 EP 1033 DI 10.1029/1999GB001224 PG 13 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA 391EK UT WOS:000166341000003 ER PT J AU Friend, AD White, A AF Friend, AD White, A TI Evaluation and analysis of a dynamic terrestrial ecosystem model under preindustrial conditions at the global scale SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Article ID BIOSPHERE MODEL; CLIMATE-CHANGE; FOREST STANDS; CONDUCTANCE; PHOTOSYNTHESIS; CARBON; TRANSPIRATION; RESPIRATION; VEGETATION; BIOMASS AB The ability of a mechanistically based dynamic terrestrial ecosystem model, Hybrid nu4.1, to predict the global distribution of vegetation, primary productivity, biomass carbon, and soil carbon under preindustrial conditions of climate, atmospheric CO2, and nitrogen deposition is evaluated. This model predicts the dynamic global distribution of eight Plant Functional Types (PFTs) by treating the interactions between individual trees, an herbaceous layer, and their physical environment at independent points on the land surface. Carbon, water, and nitrogen flows are simulated on a daily, or subdaily, basis resulting in dynamic predictions of productivity, biomass, and plant and soil carbon and nitrogen contents. Hybrid nu4.1 successfully predicts the major global patterns of preindustrial vegetation, primary productivity, biomass carbon, and soil carbon. When not subject to competition, single PFTs have much broader distributions across climatic gradients than when allowed to compete with one another, demonstrating the importance of competition in determining vegetation distribution. Trade-offs between the avoidance of frost and drought damage, growing season length, and foliage nitrogen allocation determine the relative performance of tree PFTs along climatic gradients. Six areas of disagreement between prediction and reality are noted: (1) African savanna, (2) South American grassland, (3) an area of desert in Amazonia, (4) Southern Chinese evergreen forest, (5) Siberian larch forest, and (6) tundra. These discrepancies provide useful information for future model development. C1 Inst Terr Ecol, Edinburgh Res Stn, Penicuik EH26 0QB, Midlothian, Scotland. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Friend, AD (reprint author), Rutgers State Univ, Ctr Environm Predict, New Brunswick, NJ 08901 USA. NR 59 TC 36 Z9 37 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD DEC PY 2000 VL 14 IS 4 BP 1173 EP 1190 DI 10.1029/1999GB900085 PG 18 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA 391EK UT WOS:000166341000015 ER PT J AU Momary, TW Baines, KH Yanamandra-Fisher, PA Lebofsky, LA Golisch, W Kaminski, C AF Momary, TW Baines, KH Yanamandra-Fisher, PA Lebofsky, LA Golisch, W Kaminski, C TI The saturnian satellites in the near-infrared: Absolute photometry at Ring Plane Crossing SO ICARUS LA English DT Article DE satellites of Saturn; satellite surfaces; spectrophotometry; Enceladus ID COMPOSITIONAL IMPLICATIONS; URANIAN SATELLITES; SOLAR-SYSTEM; ENCELADUS; LAPETUS; TETHYS; DIONE; SPECTROPHOTOMETRY; HYPERION; PLASMA AB We report the first absolutely calibrated photometry of nine saturnian satellites beyond 1.0 mum, in canonical near-infrared filters, including the first such spectrum of the leading side of Enceladus. The satellites were observed during Ring Plane Crossing in August and September of 1995 with the NSFCAM instrument at the NASA/IRTF These observations were contemporaneous with those of the uranian system, acquired by K. H. Baines et al. (1998, Icarus 132, 266-284), using the same instrument and filters. Results are reported for J, H, and K filters near 1.27, 1.62, and 2.20 mum a 0.1-mum-wide H' filter centered at 1.73 mum; and a 0.17-mum-wide K' filter centered at 2.27 mum. We find that the opposition surge, absolute brightness, and spectral band depths of Enceladus are consistent with fresh water ice, uncontaminated by the kinds of low albedo, spectrally neutral materials encountered in the uranian system. Specifically Enceladus displays a large near-infrared opposition surge of 0.0817 mag deg(-1) between 3.51 degrees and 0.39 degrees solar phase and a peak brightness at 1.27 mum with a geometric albedo of 0.904 +/- 0.063, while also having a J-H band depth of about 30%. All of these are consistent with a highly backscattering coating of fresh water frost on the surface of the satellite. The J-H band-depth is consistent with the relatively large (30-56%) water-ice-induced 1.52-mum band depths noted for the other saturnian satellites by Clark et al. (1984, Icarus 58, 265-281). By contrast, the darker uranian satellites display a J-H band-depth of less than 10%. From H to 1.73 mum, the full-disk albedo of Enceladus increases by 27%, similar to the uranian satellites. We find that Dione, Janus, and Epimetheus are all brighter on the leading sides than the trailing sides. However, Enceladus is brighter on the trailing side, consistent with 0.89 mum measurements of B. J. Buratti et al. (1998, Icarus 136, 223-231) and with the suggestion by M. R. Showalter et al. (1991, Icarus 94, 451-473) that negatively charged E-ring particles would preferentially impact Enceladus' trailing side. Further, there is a bluish slope to the satellite's spectrum, similar to that of the E-ring itself. These observations suggest, along with various other lines of evidence, that a substantial and evolving interaction between the E-ring and Enceladus exists, with Enceladus possibly being the source land sink) of E-ring material. Finally, our results for the 2.27-mum albedos of some of the other saturnian satellites-including Prometheus, Janus, Epimetheus, Mimas, Tethys, Dione, Rhea, and Hyperion, as well as Enceladus-are comparable to the visible albedos reported for these satellites by B. J. Buratti and J. Veverka (1984, Icarus 58, 254-264) and D. Morrison et al. (1986, Satellites (Burns and Matthews, Eds.), pp. 764-801). (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Infrared Telescope Facil, Honolulu, HI 96822 USA. RP Momary, TW (reprint author), CALTECH, Jet Prop Lab, MS 183-601,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 32 TC 10 Z9 10 U1 1 U2 2 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2000 VL 148 IS 2 BP 397 EP 406 DI 10.1006/icar.2000.6497 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 391EA UT WOS:000166340100006 ER PT J AU Cheng, AF Cole, TD Zuber, MT Smith, DE Guo, YP Davidson, F AF Cheng, AF Cole, TD Zuber, MT Smith, DE Guo, YP Davidson, F TI In-flight calibration of the Near Earth Asteroid Rendezvous laser rangefinder SO ICARUS LA English DT Article DE asteroids; asteroids, Eros; surfaces, asteroids ID FLYBY; MISSION; SPECTROMETER; 253-MATHILDE; 433-EROS; MARS; EROS; MASS AB The Near Earth Asteroid Rendezvous (NEAR) mission began a year-long rendezvous with 433 Eros on 14 February 2000, The NEAR Laser Rangefinder (NLR) will measure ranges from the spacecraft to the surface of Eros with a single shot accuracy of a few meters. The NLR topographic data, when combined with doppler tracking of the spacecraft, will enable determinations of the asteroid's shape, mass, and density and will contribute to understanding of its internal structure and collisional evolution. NLR is the first space-borne laser altimeter with an in-flight calibration capability, achieved by means of an optical fiber which directs a small portion of every outgoing laser pulse back to the receiver with a known, fixed time delay, Key results of groundbased and in-flight calibrations of NLR are presented for: in-flight measurement of receiver noise statistics, confirmation of instrument stability over the 4-year cruise to Eros, absolute calibration of range measurements for ideal targets (flat, uniform surfaces normal to the boresight), and a prediction of single-pulse detection probability and range errors in the presence of pulse dilation from nonideal target surfaces, based on a Webb's approximation model of receiver performance. We find that pulse dilation is the major source of uncertainty in the single-shot range measurements from NLR, and that this uncertainty is consistent with the 6-m range measurement requirement for NEAR. (C) 2000 Academic Press. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. MIT, Cambridge, MA 02139 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Baltimore, MD 21218 USA. RP Cheng, AF (reprint author), Johns Hopkins Univ, Appl Phys Lab, Johns Hopkins Rd, Laurel, MD 20723 USA. RI Davidson, Frederic /A-3273-2010 NR 20 TC 10 Z9 10 U1 0 U2 1 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2000 VL 148 IS 2 BP 572 EP 586 DI 10.1006/icar.2000.6487 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 391EA UT WOS:000166340100019 ER PT J AU Pravec, P Sarounova, L Benner, LAM Ostro, SJ Hicks, MD Jurgens, RF Giorgini, JD Slade, MA Yeomans, DK Rabinowitz, DL Krugly, YN Wolf, M AF Pravec, P Sarounova, L Benner, LAM Ostro, SJ Hicks, MD Jurgens, RF Giorgini, JD Slade, MA Yeomans, DK Rabinowitz, DL Krugly, YN Wolf, M TI Slowly rotating asteroid 1999 GU(3) SO ICARUS LA English DT Article DE asteroids, rotation; photometry; radar ID EARTH-APPROACHING ASTEROIDS; RADAR OBSERVATIONS; COLLISIONAL EVOLUTION; PHYSICAL MODEL; 4179-TOUTATIS; LIGHTCURVES; RATES; 253-MATHILDE; GOLDSTONE; CASTALIA AB Optical and radar observations reveal that 1999 GU(3) is subkilometer-sized object with a synodic period of 9.0 days, low visual and radar albedos, and colors more consistent with the ordinary chondrites than the vast majority of main-belt asteroids, (C) 2000 Academic Press. C1 Acad Sci Czech Republ, Inst Astron, CZ-25165 Ondrejov, Czech Republic. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Yale Univ, Dept Phys, New Haven, CT 06520 USA. Kharkiv Natl Univ, Astron Observ, UA-61022 Kharkov, Ukraine. Charles Univ, Astron Inst, CZ-18000 Prague, Czech Republic. RP Pravec, P (reprint author), Acad Sci Czech Republ, Inst Astron, CZ-25165 Ondrejov, Czech Republic. RI Pravec, Petr/G-9037-2014 NR 39 TC 8 Z9 8 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD DEC PY 2000 VL 148 IS 2 BP 589 EP 593 DI 10.1006/icar.2000.6535 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 391EA UT WOS:000166340100021 ER PT J AU Gawronski, W Beech-Brandt, JJ Ahlstrom, HG Maneri, E AF Gawronski, W Beech-Brandt, JJ Ahlstrom, HG Maneri, E TI Torque-bias profile for improved tracking of the deep space network antennas SO IEEE ANTENNAS AND PROPAGATION MAGAZINE LA English DT Article DE antenna mechanical factors; motor drives; friction; gears; torque control AB Measurements at the drives of the NASA Deep Space Network (DSN) antennas indicated that the small gap between gear teeth was causing backlash at the gearboxes and elevation bullgear. Left uncorrected, backlash will deteriorate the antenna's pointing precision. Backlash is observed not only in antennas and telescopes [1, 2], but also in precision instruments [3-6] and robots [7, 8]. Often, to reduce backlash impact on the closed-loop precision, anti-backlash controllers are designed [9-11]. At DSN, the backlash was eliminated by implementing two identical drives that impose two nonidentical torques (a.k.a, torque bias, or counter-torque). The difference between these two torques depends on the antenna load, and is shaped by the drive's electronic circuits. The paper explains the shaping principles of the circuit, and shows how the circuits can be modified to improve the antenna dynamics under external disturbances. C1 CALTECH, Jet Prop Lab, Commun Ground Syst Sect, Pasadena, CA 91109 USA. Univ Edinburgh, Dept Math & Stat, Edinburgh EH9 3JZ, Midlothian, Scotland. RP Gawronski, W (reprint author), CALTECH, Jet Prop Lab, Commun Ground Syst Sect, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM wodek.k.gawronski@jpl.nasa.gov; jason@maths.ed.ac.uk; harlow.g.ahlstrom-jr@jpl.nasa.gov; erin.j.maneri@jpl.nasa.gov NR 13 TC 16 Z9 31 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1045-9243 EI 1558-4143 J9 IEEE ANTENN PROPAG M JI IEEE Antennas Propag. Mag. PD DEC PY 2000 VL 42 IS 6 BP 35 EP 45 DI 10.1109/74.894180 PG 11 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 390PT UT WOS:000166306100005 ER PT J AU Weisbin, CR Rodriguez, G AF Weisbin, CR Rodriguez, G TI NASA robotics research for planetary surface exploration SO IEEE ROBOTICS & AUTOMATION MAGAZINE LA English DT Article DE robotic systems; planetary surface; robotic outposts C1 NASA, Jet Prop Lab, Cross Enterprise Technol Dev Program, Pasadena, CA 91109 USA. CALTECH, Jet Prop Lab, Automat & Control Sect, Pasadena, CA 91125 USA. RP Weisbin, CR (reprint author), NASA, Jet Prop Lab, Cross Enterprise Technol Dev Program, Mail Stop 179-224, Pasadena, CA 91109 USA. NR 1 TC 11 Z9 15 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1070-9932 J9 IEEE ROBOT AUTOM MAG JI IEEE Robot. Autom. Mag. PD DEC PY 2000 VL 7 IS 4 BP 25 EP 34 DI 10.1109/100.894030 PG 10 WC Automation & Control Systems; Robotics SC Automation & Control Systems; Robotics GA 394CL UT WOS:000166506400004 ER PT J AU Oberg, J AF Oberg, J TI Russia's sorry infrastructure SO IEEE SPECTRUM LA English DT Article C1 NASA Mission Control, Houston, TX USA. NR 0 TC 0 Z9 0 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9235 J9 IEEE SPECTRUM JI IEEE Spectr. PD DEC PY 2000 VL 37 IS 12 BP 47 EP 51 DI 10.1109/6.887596 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA 380NF UT WOS:000165707400016 ER PT J AU Romanofsky, RR Bernhard, JT Van Keuls, FW Miranda, FA Washington, G Canedy, C AF Romanofsky, RR Bernhard, JT Van Keuls, FW Miranda, FA Washington, G Canedy, C TI K-band phased array antennas based on Ba0.60Sr0.40TiO3 thin-film phase shifters SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article; Proceedings Paper CT IEEE MTT-S International Microwave Symposium (IMS2000) CY JUN 11-16, 2000 CL BOSTON, MA SP IEEE, MTT S DE ferroelectric devices; phase shifters; phased array antennas; scanning antennas ID MICROSTRIP REFLECTARRAY ANTENNA; MICROWAVE; DESIGN; CAPACITORS; EFFICIENCY; SYSTEMS AB This paper summarizes the development of a prototype 23.675-GHz linear 16-element scanning phased array antenna based on thin ferroelectric him coupled microstripline phase shifters and microstrip patch radiators. A new type of scanning reflectarray antenna is introduced. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Illinois, Urbana, IL 61801 USA. Ohio Aerosp Inst, Cleveland, OH 44142 USA. Ohio State Univ, Columbus, OH 43210 USA. Univ Maryland, College Pk, MD 20742 USA. RP Romanofsky, RR (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 40 TC 56 Z9 57 U1 0 U2 9 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 DEC PY 2000 VL 48 IS 12 BP 2504 EP 2510 DI 10.1109/22.899005 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA 397RN UT WOS:000166709500041 ER PT J AU Murti, MR Laskar, J Nuttinck, S Yoo, S Raghavan, A Bergman, JI Bautista, J Lai, R Grundbacher, R Barsky, M Chin, P Liu, PH AF Murti, MR Laskar, J Nuttinck, S Yoo, S Raghavan, A Bergman, JI Bautista, J Lai, R Grundbacher, R Barsky, M Chin, P Liu, PH TI Temperature-dependent small-signal and noise parameter measurements and modeling on InPHEMTs SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article; Proceedings Paper CT IEEE MTT-S International Microwave Symposium (IMS2000) CY JUN 11-16, 2000 CL BOSTON, MASSACHUSETTS SP IEEE, MTT S DE cryogenic; high electron mobility transistor (HEMT); impact ionization; low-noise amplifier (LNA); noise; small-signal model ID IMPACT IONIZATION; EQUIVALENT-CIRCUIT; FREQUENCY; HEMTS AB In this paper, we present detailed on-wafer S-parameter and noise parameter measurements and modeling of InP/InAlAs/InGaAs high electron mobility transistors (0.1-mum gate length) at cryogenic temperatures, Various physical effects influencing small-signal parameters, especially the radio-frequency (RF) transconductance and RF output resistance and their temperature dependence, are discussed in detail. Accurate on-wafer noise parameter measurements are carried out from 300 to 18 K, and the variation of the equivalent noise temperatures of drain and source (T-d and T-g) are modeled against temperature. Based on these models, a cryogenic low-noise amplifier in the Ka-band is developed with a record-low noise temperature of 10 K. C1 Georgia Inst Technol, Sch Elect & Comp Engn, Atlanta, GA 30332 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. TRW Co Inc, Redondo Beach, CA 90278 USA. RP Murti, MR (reprint author), Georgia Inst Technol, Sch Elect & Comp Engn, Atlanta, GA 30332 USA. NR 18 TC 19 Z9 20 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD DEC PY 2000 VL 48 IS 12 BP 2579 EP 2587 DI 10.1109/22.899016 PG 9 WC Engineering, Electrical & Electronic SC Engineering GA 397RN UT WOS:000166709500052 ER PT J AU Kastis, GA Barber, HB Barrett, HH Balzer, SJ Lu, D Marks, DG Stevenson, G Woolfenden, JM Appleby, M Tueller, J AF Kastis, GA Barber, HB Barrett, HH Balzer, SJ Lu, D Marks, DG Stevenson, G Woolfenden, JM Appleby, M Tueller, J TI Gamma-ray imaging using a CdZnTe pixel array and a high-resolution, parallel-hole collimator SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT Nuclear Science Symposium (NSS) CY OCT 26-28, 1999 CL SEATTLE, WASHINGTON ID MULTIPLEXER READOUT; NUCLEAR-MEDICINE; SMALL ANIMALS AB The poor performance of current parallel-hole collimators is an impediment to planar high-resolution gamma-ray imaging, even when high-resolution semiconductor detector arrays are available. High-resolution parallel-hole collimators are possible but have not been fabricated because conventional collimator construction techniques severely limit achievable bore size and septal thickness. We describe development and testing of a high-resolution collimator with 4096 260-mum square bores and 380 mum pitch, matched to our existing 2.5 cm x 2.5 cm hybrid 64x64 CdZnTe arrays with multiplexer readout. The collimator is a laminar composite of about 100 layers of W sheets produced by photolithography and has efficiency of 5x10(-5). We have demonstrated sub-millimeter spatial resolution at 140 keV in both phantom and animal imaging using this system. Images resolved individual vertebrae in the spine of a mouse and lymphatic channels and nodes in a rat. The collimator and semiconductor array could form a compact module for use in a wide variety of gamma-ray imaging systems. C1 Univ Arizona, Dept Radiol, Div Nucl Med, Tucson, AZ 85724 USA. Univ Arizona, Ctr Opt Sci, Tucson, AZ 85721 USA. Tecomet, Woburn, MA 01801 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kastis, GA (reprint author), Univ Arizona, Dept Radiol, Div Nucl Med, Tucson, AZ 85724 USA. RI Tueller, Jack/D-5334-2012; OI KASTIS, GEORGE/0000-0002-1283-0883 NR 14 TC 29 Z9 30 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 1923 EP 1927 DI 10.1109/23.914471 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MG UT WOS:000166991500032 ER PT J AU Kippen, RM Paciesas, WS Pendleton, GN Swartz, DA AF Kippen, RM Paciesas, WS Pendleton, GN Swartz, DA TI Simulation study of COSMIC - A Compton telescope all-sky monitor concept for low-energy gamma-ray astronomy SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1998 Nuclear Science Symposium (NSS) CY NOV 08-14, 1998 CL TORONTO, CANADA SP IEEE AB The highly transient nature of cosmic low-energy gamma-ray sources offers unique insight into the astrophysics of extreme processes. Sensitive, long-term, all-sky monitoring is required to make sense of the variable emission. Instrumentation for such observations must have the combination of Large effective collection area, wide field-of-view and good angular resolution. Recent advances in position-sensitive detectors and associated electronics make it possible to consider a multi-scatter Compton telescope, combined with a coded mask, as an all-sky monitor in the energy range similar to 10 keV to a few MeV. We present simulations of various configurations of such an instrument and show that it can provide a substantial improvement over other sky monitor strategies in this energy regime. C1 Univ Alabama, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Space Res Assoc, Huntsville, AL 35805 USA. RP Kippen, RM (reprint author), Univ Alabama, Huntsville, AL 35899 USA. NR 12 TC 7 Z9 7 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2050 EP 2054 DI 10.1109/23.903845 PN 2 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MK UT WOS:000166991900017 ER PT J AU Xapsos, MA Barth, JL Stassinopoulos, EG Messenger, SR Walters, RJ Summers, GP Burke, EA AF Xapsos, MA Barth, JL Stassinopoulos, EG Messenger, SR Walters, RJ Summers, GP Burke, EA TI Characterizing solar proton energy spectra for radiation effects applications SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NEVADA SP IEEE ID ACCELERATION; SPACE; PARTICLES; EVENTS; SHOCK; MODEL AB The Weibull distribution for smallest values is shown to be a useful description for solar proton event energy spectra. One advantage is its compact analytic expression, which allows easy conversion between differential and integral spectra. Another is its versatility, which is necessary for describing the highly variable spectra of concern. Furthermore, the Weibull distribution appears to be appropriate for use over broad energy ranges extending out to GeV; Examples are shown and comparisons to previously used distributions are made. An especially useful consequence of this approach for radiation effects applications is that it allows both predictive model spectra and observed spectra to be described by the same distribution. This allows spectra to be systematically ranked by severity of radiation damage caused in microelectronics. It further allows observed spectra to be related to predictive model parameters such as confidence levels. These points are demonstrated by evaluating the ionization dose deposited by various spectra in silicon behind aluminun shielding appropriate for spacecraft. C1 USN, Res Lab, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. SFA Inc, Largo, MD 20774 USA. RP Xapsos, MA (reprint author), USN, Res Lab, Code 6825, Washington, DC 20375 USA. NR 12 TC 42 Z9 43 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2218 EP 2223 DI 10.1109/23.903756 PN 3 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300010 ER PT J AU Guertin, SM Edmonds, LD Swift, GM AF Guertin, SM Edmonds, LD Swift, GM TI Angular dependence of DRAM upset susceptibility and implications for testing and analysis SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NEVADA SP IEEE ID ION TRACKS; CROSS-SECTION; DIFFUSION; DEVICES; ERRORS; MODEL AB Heavy ion irradiations of two types of commercial DRAM's reveal unexpected angular responses. One device's cross section varied by two orders of magnitude with azimuthal angle. Accurate prediction of space rates requires accommodating this effect. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Guertin, SM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 16 TC 11 Z9 12 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2380 EP 2385 DI 10.1109/23.903780 PN 3 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300034 ER PT J AU Swift, GM Guertin, SM AF Swift, GM Guertin, SM TI In-flight observations of multiple-bit upset in DRAMs SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NEVADA SP IEEE AB In interplanetary space, the Cassini solid-state recorder is experiencing the predicted number of upsets, but a very high rate of uncorrectable errors. An experimental investigation of the flight DRAMs susceptibility to multiple-bit upset (MBU) proved enlightening, revealing an unexpectedly high rate of MBUs (even caused by protons). In combination with an architectural flaw in the error correction circuitry, these explain the night anomaly. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Swift, GM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 10 TC 35 Z9 36 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2386 EP 2391 DI 10.1109/23.903781 PN 3 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300035 ER PT J AU Scheick, LZ McNulty, PJ Roth, DR AF Scheick, LZ McNulty, PJ Roth, DR TI Measurement of the effective sensitive volume of FAMOS cells of an ultraviolet erasable programmable read-only memory SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NEVADA SP IEEE ID DOSIMETER AB A method is described for measuring the sensitive volume of the oxide which makes up the collection region for erasure surrounding the floating gate of the FAMOS cell of a UVPROM using the data acquired from the output of the pins of the device. A direct measurement of the dose required to erase the Floating gate Avalanche injected metal oxide silicon (FAMOS) cell yields a measurement of the volume of oxide which collects the charge. Another method using target theory to determine the sensitive volume of the device is also presented with good agreement between the methods. The sensitive volume depends on the LET of the radiation. The ramifications for microdosimetry and cell failure are discussed as well as for the long term use aspects of nonvolatile memories. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Clemson Univ, Dept Phys & Astron, Clemson, SC 29634 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. RP Scheick, LZ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 32 TC 12 Z9 12 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2428 EP 2434 DI 10.1109/23.903788 PN 3 PG 7 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300042 ER PT J AU Reed, RA Marshall, PW Marshall, CJ Ladbury, RL Kim, HS Nguyen, LX Barth, JL LaBel, KA AF Reed, RA Marshall, PW Marshall, CJ Ladbury, RL Kim, HS Nguyen, LX Barth, JL LaBel, KA TI Energy dependence of proton damage in AlGaAs light-emitting diodes SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NEVADA SP IEEE ID INDUCED DISPLACEMENT DAMAGE; GALLIUM-ARSENIDE; RADIATION; EQUIVALENCE; SILICON; GAAS AB We measure the energy dependence of proton-induced LED degradation using large numbers of devices and incremental exposures to gain high confidence in the proton energy dependence and device-to-device variability of damage. We compare single versus double heterojunction AlGaAs technologies (emitting at 880 mm and 830 nm, respectively) to previous experimental and theoretical results. We also present a critical review of the use of nonionizing energy loss in AlGaAs for predictions of on-orbit degradation and assess the uncertainties inherent in this approach. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Orbital Sci Corp, Mclean, VA USA. Jackson & Tull Chartered Engineers, Washington, DC USA. Raytheon Informat Technol & Sci Serv, Lanham, MD USA. RP Reed, RA (reprint author), NASA, Goddard Space Flight Ctr, Code 562, Greenbelt, MD 20771 USA. NR 22 TC 33 Z9 33 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2492 EP 2499 DI 10.1109/23.903798 PN 3 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300052 ER PT J AU Johnston, AH Miyahira, TF AF Johnston, AH Miyahira, TF TI Characterization of proton damage in light-emitting diodes SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NEVADA SP IEEE AB Proton damage is investigated for several types of modern light-emitting diodes (LEDs), examining the damage from the standpoint of older models based on lifetime degradation;as well as the simpler method of normalized degradation. An empirical model is developed to describe injection-enhanced annealing in amphoterically doped LEDs. Experimental results oh "aged" devices show that wearout degradation does not decrease the sensitivity of de,ices to radiation damage. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnston, AH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 19 Z9 26 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2500 EP 2507 DI 10.1109/23.903799 PN 3 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300053 ER PT J AU Cressler, JD Hamilton, MC Mullinax, GS Li, Y Niu, GF Marshall, CJ Marshall, PW Kim, HS Palmer, MJ Joseph, AJ Freeman, G AF Cressler, JD Hamilton, MC Mullinax, GS Li, Y Niu, GF Marshall, CJ Marshall, PW Kim, HS Palmer, MJ Joseph, AJ Freeman, G TI The effects of proton irradiation on the lateral and vertical scaling of UHV/CVD SiGe HBT BiCMOS technology SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NV SP IEEE AB We present the first experimental results of the effects of 63 MeV proton irradiation on both the lateral and vertical scaling properties of SiGe HBT BiCMOS technology. Three distinct generations of (unhardened) SiGe technology are examined. The first generation SiGe HBTs experience very minor degradation in current gain at proton fluence as high as 2 x 10(13) p/cm(2), The second and third generations SiGe HBTs, however, show 60-70% degradation in current gain under similar conditions, suggesting that emitter-base spacer optimization may be required as the technology is scaled, Si nFETs from the first generation SiGe BiCMOS technology are only hard to about 40 krad equivalent gamma dose, and are limited by drain-to-source leakage along the shallow trench edge. The second generation Si nFETs, however, improve with scaling since the shallow trench is thinned, and can withstand up to 150 krad of equivalent dose. C1 Auburn Univ, Dept Elect & Comp Engn, Alabama Microelect Sci & Technol Ctr, Auburn, AL 36849 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Jackson & Tull Chartered Engineers, Washington, DC 20018 USA. IBM Microelect, Essex Jct, VT 05452 USA. IBM Microelect, Hopewell Jct, NY 12533 USA. RP Auburn Univ, Dept Elect & Comp Engn, Alabama Microelect Sci & Technol Ctr, Auburn, AL 36849 USA. NR 11 TC 24 Z9 25 U1 1 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 EI 1558-1578 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2515 EP 2520 DI 10.1109/23.903801 PN 3 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300055 ER PT J AU Scheick, LZ Guertin, SM Swift, GM AF Scheick, LZ Guertin, SM Swift, GM TI Analysis of radiation effects on individual DRAM cells SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NEVADA SP IEEE AB A novel way to measure the radiation characteristics of DRAM memory. cells is presented. Radiation exposure tends to drive retention times lower for cells. The change in retention time (the time period required for a cell to upset without refreshing) is used to measure the effect of irradiation on the DRAM cells. Both the radiation response of a single DRAM cell and the response of all cells as a statistical whole are analyzed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Scheick, LZ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 13 TC 17 Z9 19 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2534 EP 2538 DI 10.1109/23.903804 PN 3 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300058 ER PT J AU Johnston, AH Swift, GM Miyahira, TF Edmonds, LD AF Johnston, AH Swift, GM Miyahira, TF Edmonds, LD TI A model for single-event transients in comparators SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NEVADA SP IEEE ID NUMERICAL-SIMULATION; INTEGRATED-CIRCUITS; CHARGE COLLECTION; UPSET; ANALOG; SEU AB A two-step modeling approach is developed for single-event transients in linear circuits that uses the PISCES device simulation program to calculate transient currents in key internal transistor structures. Those currents are then applied at the circuit level using the SPICE circuit analysis program. The results explain the dependence of transients on input differential voltage, as well as the dependence of transient signals on output loading conditions. Error rate predictions based on laboratory testing and modeling are in close agreement with the observed number of "trips" in comparators within power control modules that have operated in a deep space environment for nearly three years. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Johnston, AH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 16 TC 37 Z9 38 U1 3 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2624 EP 2633 DI 10.1109/23.903818 PN 3 PG 10 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300072 ER PT J AU Marshall, PW Carts, MA Campbell, A McMorrow, D Buchner, S Stewart, R Randall, B Gilbert, B Reed, RA AF Marshall, PW Carts, MA Campbell, A McMorrow, D Buchner, S Stewart, R Randall, B Gilbert, B Reed, RA TI Single event effects in circuit-hardened SiGe HBT logic at Gigabit per second data rates SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NV SP IEEE ID BUFFER-LAYER; PULSED-LASER; RADIATION TOLERANCE; PROTON IRRADIATION; TEMPERATURE; SENSITIVITY; PERFORMANCE; TECHNOLOGY; UHV/CVD; UPSET AB This attempt at circuit level single event effects (SEE) hardening of SiGe HBT logic provides the first reported indication of the level of sensitivity in this important technology. Characterization over data rate up to 3 Gbps and over a broad range of heavy ion LET's provides important clues to upset mechanisms and implications for upset rate predictions. We augment ion test data,vith pulsed laser SEE testing to indicate the sensitive targets within the circuit and to provide insights into the upset mechanism(s). C1 SFA Inc, Largo, MD 20774 USA. USN, Res Lab, Washington, DC 20375 USA. Mayo Clin & Mayo Fdn, Rochester, MN 55905 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP SFA Inc, Largo, MD 20774 USA. EM pwmarshall@aol.com NR 22 TC 61 Z9 62 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 EI 1558-1578 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2669 EP 2674 DI 10.1109/23.903824 PN 3 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300078 ER PT J AU Wang, JJ Katz, RB Dhaoui, F McCollum, JL Wong, W Cronquist, BE Lambertson, RT Hamdy, E Kleyner, I Parker, W AF Wang, JJ Katz, RB Dhaoui, F McCollum, JL Wong, W Cronquist, BE Lambertson, RT Hamdy, E Kleyner, I Parker, W TI Clock buffer circuit soft errors in antifuse-based field programmable gate arrays SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT IEEE Nuclear and Space Radiation Effects Conference (NSREC) CY JUL 24-28, 2000 CL RENO, NEVADA SP IEEE ID CRITICAL CHARGE AB Three-dimensional mixed-mode device simulation is used to investigate the dock upset in an antifuse FPGA device. Two versions of the clock circuit were simulated, the original and the redesigned,vith improved SEU hardness, The threshold LET of each version was simulated both at static and during transition. Compared to the test data, the simulated results consistently underestimate the LETth. The difference between LETth at static and during transition is relatively small. This disagrees with the previous speculation that the clock upset is due to heavy-ion strikes very close to the clock edge. Efforts were also made to optimize the simulation methodology to reduce the simulation time for practicality. C1 Actel Corp, Sunnyvale, CA 94086 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Orbital Sci Corp, Greenbelt, MD 20771 USA. RP Wang, JJ (reprint author), Actel Corp, Sunnyvale, CA 94086 USA. NR 9 TC 2 Z9 2 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD DEC PY 2000 VL 47 IS 6 BP 2675 EP 2681 DI 10.1109/23.903825 PN 3 PG 7 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 402MN UT WOS:000166992300079 ER PT J AU Horwitz, JL Moore, TE AF Horwitz, JL Moore, TE TI Core plasmas in space weather regions SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article DE low-energy plasma; space plasmas ID SOFT-ELECTRON-PRECIPITATION; CLEFT ION FOUNTAIN; POLAR WIND; LATITUDE IONOSPHERE; SEMIKINETIC MODEL; ESCAPE FLUXES; TAIL LOBE; F-REGION; O+ IONS; MAGNETOSPHERE AB In recent years, there has been strong interest in "space weather" owing to increasing recognition of the myriad effects that such phenomena may have on space and even ground systems of considerable importance to man. In this paper, we describe the presence of "core" plasmas in the ionosphere and magnetosphere, which may influence various space weather phenomena. Here core plasmas are defined as plasmas with energies from zero to 50 eV(Horowitz, Rev Geophys., 1987) and originating in the terrestrial ionosphere, We first describe the ionosphere as the basic core plasma region for the overall magnetosphere-ionosphere system. We then describe the principal inner/middle magnetospheric regions-the plasmasphere, ring current, and plasma sheet regions-and how core plasmas from the ionosphere, either with little or with substantial energization, become major components of these magnetospheric regions, which are prime "space weather" regions. C1 Univ Alabama, Dept Phys, Ctr Space Plasma & Aeronom Res, Huntsville, AL 35899 USA. NASA, Goddard Space Flight Ctr, Interplanetary Phys Branch, Greenbelt, MD 20771 USA. RP Horwitz, JL (reprint author), Univ Alabama, Dept Phys, Ctr Space Plasma & Aeronom Res, Huntsville, AL 35899 USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 92 TC 1 Z9 1 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0093-3813 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD DEC PY 2000 VL 28 IS 6 BP 1840 EP 1853 DI 10.1109/27.902213 PG 14 WC Physics, Fluids & Plasmas SC Physics GA 403VP UT WOS:000167063400007 ER PT J AU Hesse, M Birn, J AF Hesse, M Birn, J TI Magnetic reconnection: Three-dimensional aspects and onset in the magnetotail SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article DE corona; kinetic and MHD; magnetic reconnection; magnetotail ID PARALLEL ELECTRIC-FIELDS; PARTICLE SIMULATION; GEOMAGNETIC TAIL; HYBRID SIMULATIONS; CURRENT SHEETS; DISSIPATION; ACCELERATION; EVOLUTION; COMPUTER; PLASMAS AB Magnetic reconnection is a fundamental plasma transport mechanism in space and laboratory plasmas. In recent years, much progress has been made in the understanding of the fundamentals of the reconnection process, including basic laws governing magnetic reconnection in three dimensions, the physical mechanisms providing the electric field in the dissipation region, and the onset of magnetic reconnection in the magnetotail of the Earth. This paper summarizes this progress and uses numerical simulations to illustrate the theoretical results in the framework of a solar and a magnetospheric example of magnetic reconnection. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Los Alamos Natl Lab, Los Alamos, NM 87545 USA. RP NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Hesse, Michael/D-2031-2012 NR 51 TC 7 Z9 7 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0093-3813 EI 1939-9375 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD DEC PY 2000 VL 28 IS 6 BP 1887 EP 1902 DI 10.1109/27.902217 PG 16 WC Physics, Fluids & Plasmas SC Physics GA 403VP UT WOS:000167063400011 ER PT J AU Owens, JK Vaughan, WW Niehuss, KO Minow, J AF Owens, JK Vaughan, WW Niehuss, KO Minow, J TI Space weather, earth's neutral upper atmosphere (thermosphere), and spacecraft orbital lifetime/dynamics SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article DE atmosphere (thermosphere): structure/dynamics; modeling; solar activity/cycle variations; space weather; spacecraft interactions ID SOLAR AB Accurate prediction of a spacecraft/satellite orbital lifetime, insertion altitude, reboost requirements, and mission performance is mainly the result of the integrated effect from knowledge of the atmospheric density space weather (solar/geomagnetic), and timeline of vehicle characteristics. Each of these elements is dependent upon a model developed to provide the inputs necessary for the use of an orbital lifetime prediction program. This paper vc ill address relative influences of these elements with emphasis an solar/geomagnetic activity; atmospheric density and drag coefficient associated with the model products used to predict orbital lifetime and related spacecraft/satellite design and operational conditions. Issues associated with the potential for improvement of the lifetime prediction model input elements will he discussed with regard to their relative contributions to improving orbital lifetime and performance predictions. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Huntsville, AL 35899 USA. Sverdrup Technol Inc, Huntsville, AL 35806 USA. RP Owens, JK (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 18 TC 1 Z9 2 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0093-3813 EI 1939-9375 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD DEC PY 2000 VL 28 IS 6 BP 1920 EP 1930 DI 10.1109/27.902220 PG 11 WC Physics, Fluids & Plasmas SC Physics GA 403VP UT WOS:000167063400014 ER PT J AU Vassiliadis, D AF Vassiliadis, D TI System identification, modeling, and prediction for space weather environments SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article DE extraterrestrial exploration; extraterrestrial phenomena; identification; modeling; neural network applications; nonlinear filters; space vehicle reliability ID NEURAL NETWORKS; MAGNETIC-FIELD; IMPULSE-RESPONSE; ELECTRIC-FIELD; MAGNETOSPHERE; DYNAMICS; CONSEQUENCES; F(O)F(2); CURRENTS; DRIVEN AB By nom nonlinear dynamical models and neural networks have been used to predict and model a wide variety of space weather environments. This review starts with the physical basis for and a brief description of the system approach. Following that. several examples illustrate practical issues in temporal and spatiotemporal prediction and modeling. The concluding remarks discuss the future developments in this research direction. C1 NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. RP Vassiliadis, D (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Code 661, Greenbelt, MD 20771 USA. NR 44 TC 15 Z9 15 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0093-3813 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD DEC PY 2000 VL 28 IS 6 BP 1944 EP 1955 DI 10.1109/27.902223 PG 12 WC Physics, Fluids & Plasmas SC Physics GA 403VP UT WOS:000167063400017 ER PT J AU Garrett, HB Whittlesey, AC AF Garrett, HB Whittlesey, AC TI Spacecraft charging, an update SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Review DE ESD; space plasma interactions; space weather; spacecraft charging ID GEOSYNCHRONOUS PLASMA ENVIRONMENT; HIGH-VOLTAGE INTERACTIONS; ELECTRODYNAMIC TETHER; STATISTICAL-ANALYSIS; SOLAR-ARRAYS; ARCING RATES; SATELLITE; WAKE; SYSTEMS; MAGNETOSPHERE AB Twenty years after the landmark SCATHA program, spacecraft charging and its associated effects continue to be major issues for earth-orbiting spacecraft. Since the time of SCATHA, spacecraft charging investigations were focused primarily on surface effects and spacecraft external surface design issues. Toda,), howe er, a significant proportion of spacecraft anomalies are believed to be caused by internal charging effects (charging and ESD events internal to the spacecraft Faraday cage envelope). This review will, following a brief summary of the state of the art in surface charging, concentrate on the problems introduced by penetrating electrons ("internal charging") and related processes (buried charge and deep dielectric charging). With the advent of tethered spacecraft and the deployment of the International Space Station, low altitude charging has taken on a new significance as well. These and issues tied to the dense, low altitude plasma environment and the auroral zone will also be briefly reviewed. C1 CALTECH, Jet Prop Lab, Safety & Miss Assurance Directorate, Pasadena, CA 91109 USA. RP Garrett, HB (reprint author), CALTECH, Jet Prop Lab, Safety & Miss Assurance Directorate, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 153 TC 70 Z9 78 U1 6 U2 19 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0093-3813 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD DEC PY 2000 VL 28 IS 6 BP 2017 EP 2028 DI 10.1109/27.902229 PG 12 WC Physics, Fluids & Plasmas SC Physics GA 403VP UT WOS:000167063400023 ER PT J AU Frederickson, AR Benson, CE Cooke, EM AF Frederickson, AR Benson, CE Cooke, EM TI Gaseous discharge plasmas produced by high-energy electron-irradiated insulators for spacecraft SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article ID DIELECTRICS; SURFACES AB High-energy electron irradiation of insulators in vacuum causes both internal regions and surfaces of insulators to achieve high (negative) static voltage relative to nearby "ground," Occasional spontaneous discharges inject pulses of partially ionized gas composed of the insulating material and surface gas-adatoms into the adjacent vacuum. The gas is capable of partially discharging the high surface potentials by carrying current across the vacuum to ''ground." The current-time waveforms were measured as a function of the spatial arrangement of the sample, test chamber electrodes, and static electric fields in order to investigate effects inside spacecraft boxes and cavities, It was found that plane-parallel electric fields are less able to sustain large discharge currents than are divergent electric fields. Also, physical confinement of the pulse of gas within the region of the electric field greatly increases the conductance of the gaseous discharge. Thus, the spatial arrangement of the sample, test chamber electrodes, and static electric field has a strong impact on the level of ESD-pulse threat to sensitive electronics posed by spontaneous discharges of irradiated insulators in spacecraft. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Wisconsin, Madison, WI 53706 USA. RP Frederickson, AR (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 26 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0093-3813 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD DEC PY 2000 VL 28 IS 6 BP 2037 EP 2047 DI 10.1109/27.902231 PG 11 WC Physics, Fluids & Plasmas SC Physics GA 403VP UT WOS:000167063400025 ER PT J AU Garrett, HB Hoffman, AR AF Garrett, HB Hoffman, AR TI Comparison of spacecraft charging environments at the Earth, Jupiter, and Saturn SO IEEE TRANSACTIONS ON PLASMA SCIENCE LA English DT Article DE plasma environments; space weather; spacecraft charging ID PLASMA; MAGNETOSPHERE; VOYAGER AB Studies of the Earth with the ATS-5, ATS-6, and SCATHA spacecraft led to the development of several simple tools for predicting the potentials to be expected on a spacecraft in the space environment. These tools have been used to estimate the expected levels of worst case charging at Jupiter and Saturn for the Galileo and the Cassini spacecraft missions. This paper reviews those results and puts them in the contest of the design issues addressed by each mission including the spacecraft design mitigation strategies adopted to limit differential charging. The model shows that shadowed surfaces in Earth orbit can reach similar to 25 kV or higher in worst case environments, For Galileo, spacecraft-to-space potentials of similar to 900 V were predicted in shadow. Since such potentials could produce possible discharges and could effect low energy plasma measurements, the outer surface of Galileo was designed to rigid conductivity requirements, Even though the surface of Galileo is not entirely conducting, after 27 orbits no adverse effects due to surface charging aside from limited effects on low energy plasma measurements have been reported. The saturnian environment results in spacecraft potentials to space in shadow of similar to 100 V or less. Although the overall surface of the Cassini spacecraft was not entirely conducting and grounded, it is shown that only in the most extreme conditions, is it expected that Cassini will experience any effects of surface charging at Saturn. C1 CALTECH, Jet Prop Lab, Safety & Miss Assurance Directorate, Pasadena, CA 91109 USA. RP Garrett, HB (reprint author), CALTECH, Jet Prop Lab, Safety & Miss Assurance Directorate, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 11 Z9 12 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0093-3813 J9 IEEE T PLASMA SCI JI IEEE Trans. Plasma Sci. PD DEC PY 2000 VL 28 IS 6 BP 2048 EP 2057 DI 10.1109/27.902232 PG 10 WC Physics, Fluids & Plasmas SC Physics GA 403VP UT WOS:000167063400026 ER PT J AU Doggett, WR Messner, WC Juang, JN AF Doggett, WR Messner, WC Juang, JN TI Global minimization of the robot base reaction force during 3-D maneuvers SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article DE base reaction force; center of mass space; disturbance minimization; global optimization; path planning; redundant; space manipulator ID MANIPULATOR AB This paper provides closed-form equations parameterizing the C-2 smooth path that globally minimizes the Euclidean norm of a robot's peak base reaction force while avoiding obstacles during three dimensional maneuvers in a gravity-free environment. In addition, the paper describes a computationally efficient technique that leads to a path typically having a peak force within 5% of the optimal path. In both cases, the equations used to define the robot's motion are formulated after mapping the initial robot configuration, final (or goal) Cartesian location, and obstacles into a new space termed the center Of mass (CM) space. This space has the advantage of being a Cartesian-like space that allows direct application of many existing control techniques, such as resolved rate control. In the CM space, a series of path segments guide the robot around the obstacles. Solving a system of equations based on these segments for boundary condition dependent constants determines the path. Currently, closed-form equations are unavailable for the boundary dependent constants, preventing exact determination of the globally optimal path, This paper introduces a five-step procedure for locating the optimal path. The final step uses a sequential quadratic programming technique to locate boundary dependent constants. The equation formulations assume that the initial configuration of the robot is known and that the robot mass and obstacle positions are constant during the maneuver. The method developed has direct applicability to redundant and nonredundant robots. A detailed example, based on a nonredundant robot avoiding a single obstacle, illustrates the concepts presented. C1 NASA, Langley Res Ctr, Syst Integrat Branch, Hampton, VA 23681 USA. Carnegie Mellon Univ, Dept Mech Engn, Pittsburgh, PA 15251 USA. NASA, Langley Res Ctr, Struct Dynam Branch, Hampton, VA 23681 USA. RP NASA, Langley Res Ctr, Syst Integrat Branch, Hampton, VA 23681 USA. NR 21 TC 2 Z9 2 U1 1 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD DEC PY 2000 VL 16 IS 6 BP 700 EP 711 DI 10.1109/70.897781 PG 12 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA 397GH UT WOS:000166684600007 ER PT J AU Park, C Lowther, SE Smith, JG Connell, JW Hergenrother, PM St Clair, TL AF Park, C Lowther, SE Smith, JG Connell, JW Hergenrother, PM St Clair, TL TI Polyimide-silica hybrids containing novel phenylethynyl imide silanes as coupling agents for surface-treated titanium alloy SO INTERNATIONAL JOURNAL OF ADHESION AND ADHESIVES LA English DT Article DE inorganic-organic hybrids; phenylethynyl imide silanes; polyimide AB Polyimide-silica hybrids composed of an organic precursor containing a novel phenylethynyl imide silane and an inorganic precursor were evaluated as an adhesion-promoting interphase between surface-treated titanium alloy and a phenylethynyl-containing imide adhesive. The phenylethynyl groups present in the organic precursor, either as a pendent or end group, can bond chemically with a phenylethynyl-containing imide adhesive during processing, while the silane groups of the organic precursor would react chemically with the inorganic precursor. In addition, the inorganic precursor is able to react with the titanium alloy to form a stable bond with the metal oxide. Bond strength and durability were evaluated by single lap shear tests at various conditions. Lap shear specimens exhibited predominantly cohesive failure after a 3-d water boil with 92% retention of the initial room temperature strength. Morphology and chemical composition of the hybrid interphase were investigated with scanning electron microscopy, X-ray photoelectron spectroscopy, and Auger electron spectroscopy, which revealed development of a silicon-gradient, hybrid structure between the metal substrate and the adhesive. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Adv Mat & Proc Branch, Hampton, VA 23681 USA. RP Park, C (reprint author), NASA, Langley Res Ctr, Adv Mat & Proc Branch, 6 W Taylor St,MS-226, Hampton, VA 23681 USA. NR 15 TC 23 Z9 26 U1 0 U2 8 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0143-7496 J9 INT J ADHES ADHES JI Int. J. Adhes. Adhes. PD DEC PY 2000 VL 20 IS 6 BP 457 EP 465 DI 10.1016/S0143-7496(00)00017-8 PG 9 WC Engineering, Chemical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 375FA UT WOS:000165387800005 ER PT J AU Mount, DM Netanyahu, NS Piatko, CD Silverman, R Wu, AY AF Mount, DM Netanyahu, NS Piatko, CD Silverman, R Wu, AY TI Quantile approximation for robust statistical estimation and kappa-enclosing problems SO INTERNATIONAL JOURNAL OF COMPUTATIONAL GEOMETRY & APPLICATIONS LA English DT Article DE robust estimation; LMS regression; minimum enclosing disk; minimum volume ball/ellipsoid/annulus estimator ID SQUARES REGRESSION; K-POINTS; CIRCLE; ALGORITHMS; OPTIMIZATION; EFFICIENT; SET AB Given a set P of n points in R-d, a fundamental problem in computational geometry is concerned with finding the smallest shape of some type that encloses all the points of P. Well-known instances of this problem include finding the smallest enclosing box, minimum volume ball, and minimum volume annulus. In this paper we consider the following variant: Given a set of n points in R-d, find the smallest shape in question that contains at least Ic points or a certain quantile of the data. This type of problem is known as a Ic-enclosing problem. We present a simple algorithmic framework for computing quantile approximations for the minimum strip, ellipsoid, and annulus containing a given quantile of the points. The algorithms run in O(n log n) time. C1 Univ Maryland, Dept Comp Sci, College Pk, MD 20742 USA. Bar Ilan Univ, Dept Math & Comp Sci, IL-52900 Ramat Gan, Israel. Univ Maryland, Ctr Automat Res, College Pk, MD 20742 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. American Univ, Dept Comp Sci & Informat Syst, Washington, DC 20016 USA. NASA, GSFC, Ctr Excellence Space Data & Informat Sci, Greenbelt, MD 20771 USA. RP Mount, DM (reprint author), Univ Maryland, Dept Comp Sci, College Pk, MD 20742 USA. RI Piatko, Christine/H-3422-2013 NR 38 TC 8 Z9 8 U1 0 U2 1 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA JOURNAL DEPT PO BOX 128 FARRER ROAD, SINGAPORE 912805, SINGAPORE SN 0218-1959 J9 INT J COMPUT GEOM AP JI Int. J. Comput. Geom. Appl. PD DEC PY 2000 VL 10 IS 6 BP 593 EP 608 DI 10.1142/S0218195900000334 PG 16 WC Computer Science, Theory & Methods; Mathematics, Applied SC Computer Science; Mathematics GA 395GH UT WOS:000166571900003 ER PT J AU Chaudhary, R Moras, R Hall, S Bohl, W AF Chaudhary, R Moras, R Hall, S Bohl, W TI Variability reduction and experimental techniques for improving the space station temporary repair patch SO INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING-THEORY APPLICATIONS AND PRACTICE LA English DT Article DE Kit for External Repair of Module Impacts; critical processes; International Space Station; microgravity AB The Kit for External Repair of Module Impacts (KERMIt) provides astronauts with a patch kit to seal damaged International Space Station (ISS) modules. Installation is crew intensive and requires injection of an adhesive to form a lasting environmental seal. A five-step analysis of KERMIt revealed two critical processes which, when controlled, provided measurable performance gains. Adhesive injection and now was the first critical process, requiring variability reduction techniques to improve adhesive flow and formation. Analysis of KERMIt installation procedures required refinement of experimental methods. Verification testing validated both methods, demonstrating the effectiveness of control techniques for refining KERMIt performance. C1 St Marys Univ, Dept Engn, San Antonio, TX 78228 USA. NASA, George C Marshall Space Flight Ctr, Flight Projects, Huntsville, AL 35812 USA. Sverdrup Inc, Huntsville, AL 35812 USA. RP Chaudhary, R (reprint author), St Marys Univ, Dept Engn, 1 Camino Santa Maria, San Antonio, TX 78228 USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU UNIV CINCINNATI INDUSTRIAL ENGINEERING PI CINCINNATI PA UNIV CINCINNATI, CINCINNATI, OH 45221-0116 USA SN 1072-4761 J9 INT J IND ENG-THEORY JI Int. J. Ind. Eng.-Theory Appl. Pract. PD DEC PY 2000 VL 7 IS 4 BP 304 EP 308 PG 5 WC Engineering, Industrial; Engineering, Manufacturing SC Engineering GA 383CN UT WOS:000165865700006 ER PT J AU Benford, DJ Allen, CA Chervenak, JA Freund, MM Kutyrev, AS Moseley, SH Shafer, RA Staguhn, JG Grossman, EN Hilton, GC Irwin, KD Martinis, JM Nam, SW Reintsema, OD AF Benford, DJ Allen, CA Chervenak, JA Freund, MM Kutyrev, AS Moseley, SH Shafer, RA Staguhn, JG Grossman, EN Hilton, GC Irwin, KD Martinis, JM Nam, SW Reintsema, OD TI Multiplexed readout of superconducting bolometers SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article DE bolometers; SQUIDs; multiplexing; transition edge sensors; far infrared; submillimeter ID ARRAYS; DESIGN AB Studies of emission in the far-infrared and submillimeter from astrophysical sources require large arrays of detectors containing hundreds to thousands of elements. A multiplexed readout is necessary for practical implementation of such arrays, and can be developed using SQUIDs, such that, e.g., a 32x32 array of bolometers can be read out using similar to 100 wires rather than the >2000 needed with a brute force expansion of existing arrays. These bolometer arrays are made by micromachining techniques, using superconducting transition, edge sensors as the thermistors. We describe the development of this multiplexed superconducting bolometer array architecture as a step toward bringing about the first astronomically useful arrays of this design. This technology will be used in the SAFIRE instrument on SOFIA, and is a candidate for a wide variety of other spectroscopic and photometric instruments. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NIST, Boulder, CO 80305 USA. RP Benford, DJ (reprint author), NASA, Goddard Space Flight Ctr, Code 685, Greenbelt, MD 20771 USA. RI Benford, Dominic/D-4760-2012; Moseley, Harvey/D-5069-2012 OI Benford, Dominic/0000-0002-9884-4206; NR 14 TC 27 Z9 27 U1 0 U2 4 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0195-9271 J9 INT J INFRARED MILLI JI Int. J. Infrared Millimeter Waves PD DEC PY 2000 VL 21 IS 12 BP 1909 EP 1916 DI 10.1023/A:1006752416612 PG 8 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA 379QN UT WOS:000165654100001 ER PT J AU Vaidyanathan, R Walish, J Lombardi, JL Kasichainula, S Calvert, P Cooper, KC AF Vaidyanathan, R Walish, J Lombardi, JL Kasichainula, S Calvert, P Cooper, KC TI The extrusion freeforming of functional ceramic prototypes SO JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY LA English DT Article ID FABRICATION AB Extrusion freeform fabrication (EFF) and fused deposition of ceramics (FDC) processes ave established extrusion-based freeforming techniques capable of fabricating complex shaped monolithic ceramic prototypes by the sequential deposition and solidification of green ceramic feedstock. In these processes, ceramic parts are produced using a commercially available Stratasys 3-D Modeler retrofitted ed with modified extrusion heads suitable for extruding ceramic materials. The manufactured objects have good dimensional tolerances as well as engineering compositions and microstructures. The process is flexible and can be used for different monolithic ceramic materials such as silicon nitride, alumina, and zirconia. C1 Adv Ceram Res, Tucson, AZ 85706 USA. Univ Arizona, Tucson, AZ USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Adv Ceram Res, 3292 E Hemisphere Loop, Tucson, AZ 85706 USA. EM r.vaidyanathan@acrtucson.com NR 17 TC 15 Z9 17 U1 2 U2 7 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 184 THORN HILL RD, WARRENDALE, PA 15086 USA SN 1047-4838 J9 JOM-J MIN MET MAT S JI JOM-J. Miner. Met. Mater. Soc. PD DEC PY 2000 VL 52 IS 12 BP 34 EP 37 DI 10.1007/s11837-000-0066-4 PG 4 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing SC Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing GA 381YD UT WOS:000165790900007 ER PT J AU Kummerow, C Simpson, J Thiele, O Barnes, W Chang, ATC Stocker, E Adler, RF Hou, A Kakar, R Wentz, F Ashcroft, P Kozu, T Hong, Y Okamoto, K Iguchi, T Kuroiwa, H Im, E Haddad, Z Huffman, G Ferrier, B Olson, WS Zipser, E Smith, EA Wilheit, TT North, G Krishnamurti, T Nakamura, K AF Kummerow, C Simpson, J Thiele, O Barnes, W Chang, ATC Stocker, E Adler, RF Hou, A Kakar, R Wentz, F Ashcroft, P Kozu, T Hong, Y Okamoto, K Iguchi, T Kuroiwa, H Im, E Haddad, Z Huffman, G Ferrier, B Olson, WS Zipser, E Smith, EA Wilheit, TT North, G Krishnamurti, T Nakamura, K TI The status of the Tropical Rainfall Measuring Mission (TRMM) after two years in orbit SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID RADAR; PRECIPITATION; ALGORITHM; SENSORS AB The Tropical Rainfall Measuring Mission (TRMM) satellite was launched on 27 November 1997, and data from all the instruments first became available approximately 30 days after the launch. Since then, much progress has been made in the calibration of the sensors, the improvement of the rainfall algorithms, and applications of these results to areas such as data assimilation and model initialization. The TRMM Microwave Imager (TMI) calibration has been corrected and verified to account for a small source of radiation leaking into the TMI receiver. The precipitation radar calibration has been adjusted upward slightly (by 0.6 dBZ) to match better the ground reference targets; the visible and infrared sensor calibration remains largely unchanged. Two versions of the TRMM rainfall algorithms are discussed. The at-launch (version 4) algorithms showed differences of 40% when averaged over the global Tropics over 30-day periods. The improvements to the rainfall algorithms that were undertaken after launch are presented, and intercomparisons of these products (version 5) show agreement improving to 24% for global tropical monthly averages. The ground-based radar rainfall product generation is discussed. Quality-control issues have delayed the routine production of these products until the summer of 2000, but comparisons of TRMM products with early versions of the ground validation products as well as with rain gauge network data suggest that uncertainties among the TRMM algorithms are of approximately the same magnitude as differences between TRMM products and ground-based rainfall estimates. The TRMM field experiment program is discussed to describe active areas of measurements and plans to use these data for further algorithm improvements. In addition to the many papers in this special issue, results coming from the analysis of TRMM products to study the diurnal cycle, the climatological description of the vertical profile of precipitation, storm types, and the distribution of shallow convection, as well as advances in data assimilation of moisture and model forecast improvements using TRMM data, are discussed in a companion TRMM special issue in the Journal of Climate (1 December 2000, Vol. 13, No. 23). C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA Headquarters, Washington, DC USA. Remote Sensing Syst, Santa Rosa, CA USA. Shimane Univ, Shimane, Japan. Aerospace Corp, Los Angeles, CA 90009 USA. Commun Res Lab, Tokyo, Japan. CALTECH, Jet Prop Lab, Pasadena, CA USA. Sci Syst & Applicat Inst, Lanham, MD USA. Univ Maryland Baltimore Cty, Baltimore, MD 21228 USA. Univ Utah, Salt Lake City, UT USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Texas A&M Univ, College Stn, TX USA. Florida State Univ, Tallahassee, FL 32306 USA. Nagoya Univ, Nagoya, Aichi, Japan. RP Kummerow, C (reprint author), Colorado State Univ, Dept Atmospher Sci, Ft Collins, CO 80523 USA. EM kummerow@atmos.colostate.edu RI North, Gerald/G-1019-2011; Hou, Arthur/D-8578-2012; Wilheit, Thomas/G-9438-2012; Huffman, George/F-4494-2014; PMM, JAXA/K-8537-2016 OI Huffman, George/0000-0003-3858-8308; NR 28 TC 660 Z9 698 U1 4 U2 46 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 1965 EP 1982 DI 10.1175/1520-0450(2001)040<1965:TSOTTR>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000002 ER PT J AU Rodgers, E Olson, W Halverson, J Simpson, J Pierce, H AF Rodgers, E Olson, W Halverson, J Simpson, J Pierce, H TI Environmental forcing of supertyphoon Paka's (1997) latent heat structure SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID TROPICAL CYCLONE INTENSITY; MEASURING MISSION TRMM; HURRICANE INTENSIFICATION; ANGULAR-MOMENTUM; OUTFLOW LAYER; TOTAL OZONE; PRECIPITATION; EVOLUTION; ATLANTIC; CLOUD AB The distribution and intensity of total (i.e., combined stratified and convective processes) rain rate/latent heat release (LHR) were derived for Tropical Cyclone Paka during the period 9-21 December 1997 from the F-10, F-11, F-13, and F-14 Defense Meteorological Satellite Special Sensor Microwave Imager and the Tropical Rainfall Measuring Mission Microwave Imager observations. These observations were frequent enough to capture three episodes of inner-core convective bursts and a convective rainband cycle that preceded periods of rapid intensification. During these periods of convective bursts, satellite sensors revealed that the rain rates/LHR 1) increased within the inner-core region, 2) were mainly convectively generated (nearly a 65% contribution), 3) propagated inward, 4) extended upward within the mid- and upper troposphere, and 5) became electrically charged. These factors may have increased the areal mean ascending motion in the mid- and upper-troposphere eyewall region, creating greater cyclonic angular momentum, and, thereby, warming the center and intensifying the system. Radiosonde measurements from Kwajalein Atoll and Guam, sea surface temperature observations, and the European Centre for Medium-Range Forecasts analyses were used to examine the necessary and sufficient conditions for initiating and maintaining these inner-core convective bursts. For example, the necessary conditions such as the atmospheric thermodynamics [i.e., cold tropopause temperatures, moist troposphere, and warm SSTs (>26 degreesC)] fulfill the necessary conditions and suggested that the atmosphere was ideally suited for Paka's maximum potential intensity to approach supertyphoon strength. Further, Paka encountered moderate vertical wind shear (<15 m s(-1)) before interacting with the westerlies on 21 December. The sufficient conditions that include horizontal moisture and the upper-tropospheric eddy relative angular momentum fluxes, on the other hand, appeared to have some influence on Paka's convective burst. However, the horizontal moisture flux convergence values in the outer core were weaker than some of the previously examined tropical cyclones. Also, the upper-tropospheric outflow generation of eddy relative angular momentum flux convergence was much less than that found during moderate tropical cyclone-trough interaction. These results indicated how important the external necessary condition and the internal forcing (i.e., convective rainband cycle) were in generating Paka's convective bursts as compared with the external sufficient forcing mechanisms found in higher-latitude tropical cyclones. Later, as Paka began to interact with the westerlies, both the necessary (i.e., strong vertical wind shear and colder SSTs) and sufficient (i.e., dry air intrusion) external forcing mechanisms helped to decrease Paka's rain rate. C1 NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. Sci & Syst Applicat Inc, Lanham, MD USA. RP Simpson, J (reprint author), NASA, Goddard Space Flight Ctr, Earth Sci Directorate, Atmospheres Lab, Code 912,Bldg 33,Rm C407, Greenbelt, MD 20771 USA. EM simpson@agnes.gsfc.nasa.gov NR 58 TC 29 Z9 29 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 1983 EP 2006 DI 10.1175/1520-0450(2001)040<1983:EFOSPS>2.0.CO;2 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000003 ER PT J AU Adler, RF Huffman, GJ Bolvin, DT Curtis, S Nelkin, EJ AF Adler, RF Huffman, GJ Bolvin, DT Curtis, S Nelkin, EJ TI Tropical rainfall distributions determined using TRMM combined with other satellite and rain gauge information SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID SQUALL LINES; EL-NINO; PRECIPITATION; OSCILLATION AB A technique is described to use Tropical Rainfall Measuring Mission (TRMM) combined radar-radiometer information to adjust geosynchronous infrared satellite data [the TRMM Adjusted Geostationary Operational Environmental Satellite Precipitation Index (AGPI)]. The AGPI is then merged with rain gauge information (mostly over land) to provide finescale (1 degrees latitude X 18 longitude) pentad and monthly analyses, respectively. The TRMM merged estimates are 10% higher than those from the Global Precipitation Climatology Project (GPCP) when integrated over the tropical oceans (37 degreesN-37 degreesS) for 1998, with 20% differences noted in the most heavily raining areas. In the dry subtropics the TRMM values are smaller than the GPCP estimates. The TRMM merged product tropical-mean estimates for 1998 are 3.3 mm day(-1) over ocean and 3.1 mm day(-1) over land and ocean combined. Regional differences are noted between the western and eastern Pacific Ocean maxima when TRMM and GPCP are compared. In the eastern Pacific rain maximum the TRMM and GPCP mean values are nearly equal, which is very different from the other tropical rainy areas where TRMM merged product estimates are higher. This regional difference may indicate that TRMM is better at taking into account the vertical structure of the rain systems and the difference in structure between the western and eastern (shallower) Pacific convection. Comparisons of these TRMM merged analysis estimates with surface datasets shows varied results; the bias is near zero when compared with western Pacific Ocean atoll rain gauge data, but is significantly positive as compared with Kwajalein radar estimates (adjusted by rain gauges). Over land the TRMM estimates also show a significant positive bias. The inclusion of gauge information in the final merged product significantly reduces the bias over land, as expected. The monthly precipitation patterns produced by the TRMM merged data process clearly show the evolution of the El Nino-Southern Oscillation (ENSO) tropical precipitation pattern from early 1998 (El Nino) to early 1999 (La Nina) and beyond. The El Nino-minus-La Nina difference map shows the expected eastern Pacific maximum, the "Maritime Continent'' minima, and other tropical and midlatitude features, very similar to those detected by the GPCP analyses. However, summing the El Nino-minus-La Nina differences over the global tropical oceans yields divergent answers for interannual changes from TRMM, GPCP, and other estimates. This emphasizes the need for additional validation and analysis before it is feasible to understand the relations between global precipitation anomalies and Pacific Ocean ENSO temperature changes. C1 NASA, Atmospheres Lab, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Greenbelt, MD USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. RP Adler, RF (reprint author), NASA, Atmospheres Lab, Greenbelt, MD 20771 USA. EM adler@agnes.gsfc.nasa.gov RI Curtis, Scott/C-1115-2013; Huffman, George/F-4494-2014; OI Huffman, George/0000-0003-3858-8308; Curtis, Scott/0000-0001-9065-8639 NR 19 TC 202 Z9 208 U1 0 U2 22 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2007 EP 2023 DI 10.1175/1520-0450(2001)040<2007:TRDDUT>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000004 ER PT J AU Iguchi, T Kozu, T Meneghini, R Awaka, J Okamoto, K AF Iguchi, T Kozu, T Meneghini, R Awaka, J Okamoto, K TI Rain-profiling algorithm for the TRMM precipitation radar SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID DUAL-FREQUENCY ALGORITHMS; SPACEBORNE RADAR; SINGLE-FREQUENCY; AIRBORNE; TESTS AB This paper describes the Tropical Rainfall Measuring Mission (TRMM) standard algorithm that estimates the vertical profiles of attenuation-corrected radar reflectivity factor and rainfall rate. In particular, this paper focuses on the critical steps in the algorithm. These steps are attenuation correction, selection of the default drop size distribution model including vertical variations, and correction for the nonuniform beam-filling effect. The attenuation correction is based on a hybrid of the Hitschfeld-Bordan method and a surface reference method. A new algorithm to obtain an optimum weighting function is described. The nonuniform beam-filling problem is analyzed as a two-dimensional problem. The default drop size distribution model is selected according to the criterion that the attenuation estimates derived from the model and the independent estimates from the surface reference with the nonuniform beam-filling correction are consistent for rain over ocean. It is found that the drop size distribution models that are consistent for convective rain over ocean are not consistent over land, indicating a change in the size distributions associated with convective rain over land and ocean, respectively. C1 Commun Res Lab, Global Environm Div, Tokyo 1848795, Japan. Shimane Univ, Dept Elect & Control Syst Engn, Matsue, Shimane, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Hokkaido Tokai Univ, Dept Informat Sci, Sapporo, Hokkaido, Japan. Univ Osaka Prefecture, Dept Aerosp Engn, Sakai, Osaka 591, Japan. RP Iguchi, T (reprint author), Commun Res Lab, Global Environm Div, 4-2-1 Nukui Kita Machi, Tokyo 1848795, Japan. EM iguchi@crl.go.jp RI PMM, JAXA/K-8537-2016 NR 20 TC 629 Z9 657 U1 5 U2 40 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2038 EP 2052 DI 10.1175/1520-0450(2001)040<2038:RPAFTT>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000006 ER PT J AU Meneghini, R Iguchi, T Kozu, T Liao, L Okamoto, K Jones, JA Kwiatkowski, J AF Meneghini, R Iguchi, T Kozu, T Liao, L Okamoto, K Jones, JA Kwiatkowski, J TI Use of the surface reference technique for path attenuation estimates from the TRMM precipitation radar SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID RAIN-RATE; SPACEBORNE RADAR; SINGLE-FREQUENCY; TOGA COARE; WIND; SIMULATIONS; ALGORITHMS; AIRBORNE; PROFILE AB Estimates of rain rate from the precipitation radar (PR) aboard the Tropical Rainfall Measuring Mission (TRMM) satellite require a means by which the radar signal attenuation can be corrected. One of the methods available is the surface reference technique in which the radar surface return in rain-free areas is used as a reference against which the path-integrated attenuation is obtained. Despite the simplicity of the basic concept, an assessment of the reliability of the technique is difficult because the statistical properties of the surface return depend not only on surface type (land/ocean) and incidence angle, but on the detailed nature of the surface scattering. In this paper, a formulation of the technique and a description of several surface reference datasets that are used in the operational algorithm are presented. Applications of the method to measurements from the PR suggest that it performs relatively well over the ocean in moderate to heavy rains. An indication of the reliability of the results can be gained by comparing the estimates derived from different reference datasets. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Commun Res Lab, Global Environm Div, Tokyo, Japan. Shimane Univ, Dept Elect & Control Syst Engn, Matsue, Shimane, Japan. Caelum Res Corp, Rockville, MD USA. Univ Osaka Prefecture, Dept Aerosp Engn, Sakai, Osaka, Japan. Raytheon ITSS Inc, Lanham, MD USA. George Mason Univ, Fairfax, VA 22030 USA. RP Meneghini, R (reprint author), NASA, Goddard Space Flight Ctr, Code 975, Greenbelt, MD 20771 USA. EM bob@priam.gsfc.nasa.gov RI PMM, JAXA/K-8537-2016 NR 24 TC 164 Z9 169 U1 1 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2053 EP 2070 DI 10.1175/1520-0450(2001)040<2053:UOTSRT>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000007 ER PT J AU Heymsfield, GM Geerts, B Tian, L AF Heymsfield, GM Geerts, B Tian, L TI TRMM precipitation radar reflectivity profiles as compared with high-resolution airborne and ground-based radar measurements SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID SPACEBORNE RADAR; CONVECTIVE-SYSTEMS; SINGLE-FREQUENCY; RAIN-RATE; ALGORITHMS; RADIOMETER; RETRIEVAL; AIRCRAFT; TESTS AB Orbital Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) products are evaluated by simultaneous comparisons with high-resolution data from the high-altitude ER-2 Doppler radar (EDOP) and ground-based radars. The purpose is not to calibrate any radar or to validate surface rainfall estimates, but rather to evaluate the vertical reflectivity structure, which is important in TRMM rain-type classification and estimation of latent heating profiles. The radars used in this study have considerably different viewing geometries and resolutions, demanding nontrivial mapping procedures in common earth-relative coordinates. Mapped vertical cross sections and mean profiles of reflectivity from the PR, EDOP, and ground-based radars are compared for six cases. These cases cover a stratiform frontal rainband, convective cells of various sizes and stages, and a hurricane. For precipitating systems larger than the PR footprint size, PR reflectivity profiles compare very well with high-resolution measurements thresholded to the PR minimum reflectivity, and derived variables such as bright-band height and rain types are accurate, even at off-nadir PR scan angles. Convective rainfall is marked by high-horizontal reflectivity gradients; therefore its reflectivity distribution is spread out because of the PR antenna illumination pattern and by nonuniform beamfilling effects. In these cases, rain-type classification may err and be biased toward the stratiform type, and the average reflectivity tends to be underestimated. The limited sensitivity of the PR implies that large portions of the upper regions of precipitation systems remain undetected. This implication applies to all cases, but the discrepancy is larger for smaller cells for which limited sensitivity is compounded by incomplete beamfilling. These findings have important implications for gridded TRMM products such as monthly mean rainfall. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Sci Syst Applicat Inc, Lanham, MD USA. Univ Space Res Assoc, Seabrook, MD USA. RP Heymsfield, GM (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. EM heymsfield@agnes.gsfc.nasa.gov NR 31 TC 51 Z9 55 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2080 EP 2102 DI 10.1175/1520-0450(2001)040<2080:TPRRPA>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000009 ER PT J AU Viltard, N Kummerow, C Olson, WS Hong, Y AF Viltard, N Kummerow, C Olson, WS Hong, Y TI Combined use of the radar and radiometer of TRMM to estimate the influence of drop size distribution on rain retrievals SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID PRECIPITATION; PARAMETERIZATION; CLOUDS; MODEL; PROFILES; SENSORS AB A combination of passive microwave and radar observations from the Tropical Rainfall Measuring Mission (TRMM) satellite is used to investigate the consistency between the two sensors. Rather than relying on some absolute "truth'' to verify retrievals, this paper focuses on one assumption-namely, the drop size distribution (DSD)-and how different DSDs lead to improved or reduced consistency. Results from a case in the central Pacific suggest that a crude consistency may be achieved if a different drop size is used for the radiometer and the radar. In this particular case, a Marshall-Palmer or a gamma distribution with the shape parameters properly set leads to similar results. Although this study offers no independent validation of its conclusions, it does demonstrate that rainfall validation need not be confined to surface rainfall measurements, which are only loosely related to the volumetric observations made by most sensors. As mean size distributions of raindrops are measured in the TRMM field experiments by disdrometers, profilers, multiparameter radars, and direct aircraft observations, the technique presented in this paper can be applied on a storm-by-storm basis, and conclusions can be verified directly. C1 Univ Space Res Assoc, Greenbelt, MD USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. Caelum Res Corp, Greenbelt, MD USA. RP Viltard, N (reprint author), CETP, 10-12 Ave Europe, F-78140 Velizy, France. EM viltard@cetp.ipsl.fr OI Hong, Yang/0000-0001-8720-242X NR 24 TC 41 Z9 42 U1 3 U2 6 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2103 EP 2114 DI 10.1175/1520-0450(2001)040<2103:CUOTRA>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000010 ER PT J AU Atlas, D Ulbrich, CW AF Atlas, D Ulbrich, CW TI An observationally based conceptual model of warm oceanic convective rain in the tropics SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID FRAGMENT SIZE DISTRIBUTIONS; DROP-SIZE; RADAR REFLECTIVITY; MESOSCALE SYSTEMS; AIR MOTION; TOGA COARE; EVOLUTION; SPECTRA; BREAKUP; CLOUDS AB Distinctively different Z-R relations for initial convective and transition rain at the surface were found during the Tropical Ocean and Global Atmosphere Coupled Ocean-Atmosphere Response Experiment. Initial convective rain (of 20-30-min duration) is marked by nearly constant median volume diameter of D-o approximate to 2 mm and narrow drop size spectra, while R rises to >50 mm h(-1). The constant form of the drop spectra independent of rain rate indicates an equilibrium distribution that accounts for the near linearity between Z and R. The form of the distribution differs from those previously reported, however. In contrast, the airborne raindrop measurements at 3 km in climatologically similar conditions show size spectra closely resembling the equilibrium collision-coalescence-breakup spectra of Hu and Srivastava and others at R > 20 mm h(-1). The center of the plateau (of near-constant size) of these spectra repeatedly occurs at a drop size of 1 +/- 0.1 mm whose fall speed equals the updraft speed. This suggests a mechanism in which the updraft decreases the rate of fall of the drops relative to the surface, thus extending the residence time for collisions and reducing the depth of fall required for equilibrium to be reached. At the same time the updraft separates the large fast-falling drops from the smaller ones. The large ones fall within the convergent core of the convective cell to form the narrow equilibrium drop spectra observed at the surface, while the small ones rise into the divergent air above the updraft maximum and fall out elsewhere if they survive. Also, the updrafts in warm tropical convective clouds that produce R > 20 mm h(-1) are commonly 4-5 m s(-1), the speeds necessary to support the 0.5-1.5-mm-diameter range of drop sizes at which the collision rate is maximized. The warm convective clouds of the western tropical Pacific Ocean appear to be well tuned to this process. The implications for radar measurements of rainfall are also treated. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Clemson Univ, Dept Phys & Astron, Clemson, SC 29634 USA. RP Atlas, D (reprint author), NASA, Goddard Space Flight Ctr, Code 912-1, Greenbelt, MD 20771 USA. EM datlas@radar.gsfc.nasa.gov NR 44 TC 39 Z9 40 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2165 EP 2181 DI 10.1175/1520-0450(2001)040<2165:AOBCMO>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000014 ER PT J AU Amitai, E AF Amitai, E TI Systematic variation of observed radar reflectivity-rainfall rate relations in the tropics SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID Z-R RELATIONS; PROBABILITY MATCHING METHOD; GAUGE DATA; CLASSIFICATION; CLOUDS; STRATIFORM; SIZE; WPMM AB The Tropical Rainfall Measuring Mission Global Validation Program provides a unique opportunity to compare radar datasets from different sites, because they are analyzed in a relatively uniform procedure. Monthly observed radar reflectivity-rainfall rate (Z(e)-R) relations for four different sites that are surrounded by tipping bucket gauge networks (Melbourne, Florida; Houston, Texas; Darwin, Australia; and Kwajalein Atoll, Republic of Marshall Islands) were derived. The radar and gauge data from all sites are controlled for quality using the same algorithms, which also include an automated procedure to filter unreliable rain gauge data upon comparison with radar data. The relations are generated by two different methods. The first method is based on using a power law Z(e)-R with a fixed exponent of 1.4, and the second is based on matching unconditional probabilities of rain rates as measured by the gauge to radar-observed reflectivities and is known as the window probability matching method (WPMM). Both methods tune the radar observations to a network of quality-controlled gauges to adjust the total monthly rainfall to match the gauges. Separate relations are generated for convective and stratiform rain, as classified by the horizontal reflectivity structure. In the WPMM-based Z(e)-R relations, a given Z(e) was matched to a much lower R in convective rainfall than in stratiform rainfall. These relations were found to be curved lines in log-log space rather than a straight-line power law. The WPMM-based Z(e)-R curves demonstrated systematic variation between the convective and stratiform rain, but the power law-based Z(e)-R curves showed no systematic trend. The systematic variation in the relations shown here contradicts previous findings in which the classification is based only on the existence or nonexistence of brightband signature. The latter indicates a higher reflectivity in stratiform rain as compared with that in convective rain, for a given rain rate. Recent studies, based on disdrometer data, suggest that during a typical event there are three principal types of rain (convective, transition, and stratiform), each characterized by a different type of Z-R relation. The current study suggests that to distinguish each type, both the horizontal and the vertical reflectivity field structure should be analyzed. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. RP Amitai, E (reprint author), NASA, Goddard Space Flight Ctr, Code 912-1, Greenbelt, MD 20771 USA. EM eyal@radar.gsfc.nasa.gov NR 37 TC 29 Z9 29 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2198 EP 2208 DI 10.1175/1520-0450(2001)040<2198:SVOORR>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000016 ER PT J AU Williams, E Rothkin, K Stevenson, D Boccippio, D AF Williams, E Rothkin, K Stevenson, D Boccippio, D TI Global lightning variations caused by changes in thunderstorm flash rate and by changes in the number of thunderstorms SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID SURFACE AIR-TEMPERATURE; SCHUMANN RESONANCE; THUNDERCLOUD PARAMETERS; CONDITIONAL INSTABILITY; ELECTRICAL CIRCUIT; FREQUENCY; CLOUD AB Global lightning activity is highly variable on many timescales. This variability is attributable to changes in the flash rate per thunderstorm, the number of thunderstorms, or a combination. The Tropical Rainfall Measuring Mission provides lightning observations from the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) in space. Both are used to examine the response of these parameters to thermodynamic forcing of deep convection on the diurnal and annual timescales. On both timescales, the changes in the number of storms dominate the variations in total lightning activity. On the diurnal timescale, there is evidence that the mean flash rate may vary with cloud buoyancy, peaking in early afternoon and declining in late afternoon, but the contribution of number of thunderstorms is 2-3 times greater than the mean storm flash rate. On the annual timescale, almost all of the total lightning response is due to changes in the number of storms, with a negligible contribution from flash rate. Evidence is presented that the LIS/OTD "area'' is a meaningful objective identifier for a thunderstorm, despite known limitations in this data product. C1 MIT, Ralph M Parsons Lab, Cambridge, MA 02139 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Williams, E (reprint author), MIT, Ralph M Parsons Lab, Bldg 48-211, Cambridge, MA 02139 USA. EM earlew@ll.mit.edu NR 36 TC 65 Z9 75 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2223 EP 2230 DI 10.1175/1520-0450(2001)040<2223:GLVCBC>2.0.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000018 ER PT J AU Boccippio, DJ Goodman, SJ Heckman, S AF Boccippio, DJ Goodman, SJ Heckman, S TI Regional differences in tropical lightning distributions SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID OPTICAL TRANSIENT DETECTOR; CONVECTIVE RAINFALL; ICE-SCATTERING; THUNDERSTORMS; ATMOSPHERE; SENSOR; RADAR; STORM AB Observations from the National Aeronautics and Space Administration Optical Transient Detector (OTD) and Tropical Rainfall Measuring Mission (TRMM)-based Lightning Imaging Sensor (LIS) are analyzed for variability between land and ocean, various geographic regions, and different (objectively defined) convective "regimes.'' The bulk of the order-of-magnitude differences between land and ocean regional flash rates are accounted for by differences in storm spacing (density) and/or frequency of occurrence, rather than differences in storm instantaneous flash rates, which only vary by a factor of 2 on average. Regional variability in cell density and cell flash rates closely tracks differences in 85-GHz microwave brightness temperatures. Monotonic relationships are found with the gross moist stability of the tropical atmosphere, a large-scale "adjusted state'' parameter. This result strongly suggests that it will be possible, using TRMM observations, to objectively test numerical or theoretical predictions of how mesoscale convective organization interacts with the larger-scale environment. Further parameters are suggested for a complete objective definition of tropical convective regimes. C1 NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35812 USA. Univ Space Res Assoc, Huntsville, AL USA. RP Boccippio, DJ (reprint author), NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35812 USA. EM Dennis.Boccippio@msfc.nasa.gov NR 35 TC 131 Z9 146 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD DEC PY 2000 VL 39 IS 12 BP 2231 EP 2248 DI 10.1175/1520-0450(2001)040<2231:RDITLD>2.0.CO;2 PN 1-2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000019 ER PT J AU Priestley, KJ Barkstrom, BR Lee, RB Green, RN Thomas, S Wilson, RS Spence, PL Paden, J Pandey, DK Al-Hajjah, A AF Priestley, KJ Barkstrom, BR Lee, RB Green, RN Thomas, S Wilson, RS Spence, PL Paden, J Pandey, DK Al-Hajjah, A TI Postlaunch radiometric validation of the Clouds and the Earth's Radiant Energy System (CERES) Proto-flight Model on the Tropical Rainfall Measuring Mission (TRMM) spacecraft through 1999 SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID THERMISTOR BOLOMETER SENSORS AB Each Clouds and the Earth's Radiant Energy System (CERES) instrument contains three scanning thermistor bolometer radiometric channels. These channels measure broadband radiances in the shortwave (0.3-5.0 mm), total (0.3->100 mum), and water vapor window regions (8-12 mum). Ground-based radiometric calibrations of the CERES flight models were conducted by TRW Inc.'s Space and Electronics Group of Redondo Beach, California. On-orbit calibration and vicarious validation studies have demonstrated radiometric stability, defined as long-term repeatability when measuring a constant source, at better than 0.2% for the first 18 months of science data collection. This level exceeds by 2.5 to 5 times the prelaunch radiometric performance goals that were set at the 0.5% level for terrestrial energy flows and 1.0% for solar energy flows by the CERES Science Team. The current effort describes the radiometric performance of the CERES Proto-Flight Model on the Tropical Rainfall Measuring Mission spacecraft over the first 19 months of scientific data collection. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Sci Applicat Int Corp, Hampton, VA USA. RP Priestley, KJ (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. EM k.j.priestley@larc.nasa.gov NR 21 TC 26 Z9 26 U1 1 U2 6 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2249 EP 2258 DI 10.1175/1520-0450(2001)040<2249:PRVOTC>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000020 ER PT J AU Oreopoulos, L Cahalan, RF Marshak, A Wen, GY AF Oreopoulos, L Cahalan, RF Marshak, A Wen, GY TI A new normalized difference cloud retrieval technique applied to landsat radiances over the Oklahoma ARM site SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID INDEPENDENT PIXEL APPROXIMATION; SOLAR-RADIATION MEASUREMENTS; EFFECTIVE PARTICLE RADIUS; BOUNDARY-LAYER CLOUDS; OPTICAL-THICKNESS; STRATOCUMULUS; SATELLITE; ALBEDO; AIRCRAFT; ASTEX AB The authors propose a new cloud property retrieval technique that accounts for cloud side illumination and shadowing effects present at high solar zenith angles. The technique uses the normalized difference of nadir reflectivities (NDNR) at a conservative and an absorbing (with respect to liquid water) wavelength. It can be further combined with the inverse nonlocal independent pixel approximation (NIPA) of Marshak et al. that corrects for radiative smoothing, thus providing a retrieval framework where all 3D cloud effects can potentially be accounted for. The effectiveness of the new technique is demonstrated using Monte Carlo simulations. Real-world application is shown to be feasible using Thematic Mapper (TM) radiance observations from Landsat-5 over the Southern Great Plains (SGP) site of the Atmospheric Radiation Measurement (ARM) Program. For the moderately oblique (45 degrees) solar zenith angle of the available Landsat scene, NDNR gives similar regional statistics and histograms when compared with standard independent pixel approximation (IPA), but significant differences at the pixel level. Inverse NIPA is also applied for the first time on observed high-resolution radiances of overcast Landsat subscenes. The dependence of the NIPA-retrieved cloud fields on the parameters of the method is illustrated and practical issues related to the optimal choice of these parameters are discussed. It is natural to compare novel cloud retrieval techniques with standard IPA retrievals. IPA is useful in revealing the inadequacy of plane parallel theory in certain situations and in demonstrating sensitivities to parameter choices, parameterizations, and assumptions. For example, it is found that IPA has problems in matching modeled and observed band-7 (2.2 mum) reflectance values for similar to6% of the pixels, most of which are at cloud edges. For simultaneous cloud optical depth-droplet effective radius retrievals (where a conservative and an absorptive TM band are needed), it is found that the band-4 (0.83 mum)-band-7 pair was the most well behaved, having less saturation, smaller changes in nominal calibration, and better overall consistency with modeled values than other bands. Mean values of optical depth, effective radius, and liquid water path (LWP) for typical IPA retrievals using this pair are tau = 22, r(e) = 11 mum, and LWP = 157 g m(-2), respectively. Inclusion of aerosol scattering above clouds results in similar to8% decrease in mean cloud optical depth for an aerosol optical depth of 0.2. Degradation of instrument resolution up to similar to2 km has small effects on the optical property means and histograms, suggesting small actual cloud variability at these scales and/or radiative smoothing. Comparisons with surface instruments (microwave radiometer, pyranometer, and pyrgeometer) verify the statisitical adequacy of the IPA retrievals. Last, cloud fractions derived with a simple threshold method are compared with those from an automated procedure called Automatic Cloud Cover Assessment now in operational use for Landsat-7. For the northernmost 2000 scanlines of the scene, the cloud fraction Ac is 0.585 from thresholding, as compared with A(c) = 0.563 for the automated procedure, and the full scene values are A(c) = 0.870 and A(c) = 0.865, respectively. This suggests that the Landsat-7 automated procedure will likely give reliable scene-averaged cloud fractions for moderately thick clouds over continental U.S. scenes similar to SGP. C1 NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. RP Oreopoulos, L (reprint author), NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Code 913, Greenbelt, MD 20771 USA. EM lazaros@climate.gsfc.nasa.gov RI Oreopoulos, Lazaros/E-5868-2012; Cahalan, Robert/E-3462-2012; Marshak, Alexander/D-5671-2012 OI Oreopoulos, Lazaros/0000-0001-6061-6905; Cahalan, Robert/0000-0001-9724-1270; NR 40 TC 10 Z9 10 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2305 EP 2321 DI 10.1175/1520-0450(2000)039<2305:ANNDCR>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000024 ER PT J AU Merceret, FJ AF Merceret, FJ TI The coherence time of midtropospheric wind features as a function of vertical scale from 300 m to 2 km SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID RESOLUTION; PROFILER; SPECTRA AB The coherence between vertical wind profiles separated by a time lag is measured as a function of vertical scale from Doppler radar wind profiler data. Each profile covers altitudes from 6811 m to 16 261 m and is Fourier transformed over a vertical wavenumber (inverse scale) range from 0 to 3.33 x 10(-3) m(-1). Time lags between profiles of 0.083, 0.25, 0.5, 1.0, and 2.0 h are used. A correction for instrument noise is derived and is applied to the results. An empirical formula for the coherence as a function of lag and scale is presented and evaluated. The "coherence time'' is defined as the value of time lag beyond which the coherence decays below a chosen value at a given scale. A relation between coherence time and vertical scale is derived. This relation provides a measure of the lifetime of wind features in the midtroposphere as a function of their vertical scale for application to space vehicle wind loads. C1 NASA, YA D, Kennedy Space Ctr, FL 32899 USA. RP Merceret, FJ (reprint author), NASA, YA D, Kennedy Space Ctr, FL 32899 USA. EM francis.merceret-1@ksc.nasa.gov NR 12 TC 0 Z9 0 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2409 EP 2420 DI 10.1175/1520-0450(2000)039<2409:TCTOMW>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000031 ER PT J AU Atlas, D Matrosov, SY Heymsfield, AJ Chou, MD Wolff, DB AF Atlas, D Matrosov, SY Heymsfield, AJ Chou, MD Wolff, DB TI Radar and radiation properties of ice clouds (vol 34, pg 2329, 1995) SO JOURNAL OF APPLIED METEOROLOGY LA English DT Correction C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NOAA, OAR, ETL, Boulder, CO USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Appl Res Corp, Landover, MD 20785 USA. RP Atlas, D (reprint author), NASA, Goddard Space Flight Ctr, Code 912-1, Greenbelt, MD 20771 USA. EM datlas@radar.gsfc.nasa.gov RI Heymsfield, Andrew/E-7340-2011 NR 2 TC 0 Z9 0 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PY 2000 VL 39 IS 12 BP 2495 EP 2495 DI 10.1175/1520-0450(2000)039<2495:C>2.0.CO;2 PG 1 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 386BJ UT WOS:000166040000038 ER PT J AU LeBlanc, A Lin, C Shackelford, L Sinitsyn, V Evans, H Belichenko, O Schenkman, B Kozlovskaya, I Oganov, V Bakulin, A Hedrick, T Feeback, D AF LeBlanc, A Lin, C Shackelford, L Sinitsyn, V Evans, H Belichenko, O Schenkman, B Kozlovskaya, I Oganov, V Bakulin, A Hedrick, T Feeback, D TI Muscle volume, MRI relaxation times (T2), and body composition after spaceflight SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE bone; dual-energy X-ray absorptiometry; microgravity; Mir space station; Spacelab; magnetic resonance imaging ID FLIGHT; MASS AB Postflight changes in muscle volume, calf muscle transverse relaxation time, and total body composition were measured in 4 crewmembers after a 17-day mission and in 14-16 crewmembers in multiple shuttle/Mir missions of 16- to 28-wk duration. During the 17-day mission, all muscle regions except the hamstrings significantly decreased 3-10% compared with baseline. During the shuttle/Mir missions, there were significant decreases in muscle volume (5-17%) in all muscle groups except the neck. These changes, which reached a new steady state by 4 mo of flight or less, were reversed within 30-60 days after landing. Postflight swelling and elevation of calf muscle transverse relaxation time persisted for several weeks after flight, which suggests possible muscle damage. In contrast to the 17-day flight, in which loss in fat, but not lean body mass, was found (25), losses in bone mineral content and lean body mass, but not fat, were seen after the longer shuttle/Mir missions. The percent losses in total body lean body mass and bone mineral content were similar at similar to3.4-3.5%, whereas the pelvis demonstrated the largest regional bone loss at 13%. C1 Baylor Coll Med, Dept Med, Houston, TX 77030 USA. NASA, Lyndon B Johnson Space Ctr, Musculosketal Lab, Houston, TX 77058 USA. Russian Acad Med Sci, Cardiol Res Ctr, Dept CT & MRI, Moscow, Russia. Minist Hlth, Inst Biomed Problems, Moscow 121552, Russia. RP LeBlanc, A (reprint author), 6565 Fannin St,Mail Code BB1-70A, Houston, TX 77030 USA. RI Sinitsyn, Valentin/A-5417-2016; Kozlovskaya, Inesa/R-9729-2016 OI Sinitsyn, Valentin/0000-0002-5649-2193; NR 24 TC 146 Z9 151 U1 1 U2 3 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD DEC PY 2000 VL 89 IS 6 BP 2158 EP 2164 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 380YZ UT WOS:000165736400008 PM 11090562 ER PT J AU Bigbee, AJ Gosselink, KL Roy, RR Grindeland, RE Edgerton, VR AF Bigbee, AJ Gosselink, KL Roy, RR Grindeland, RE Edgerton, VR TI Bioassayable growth hormone release in rats in response to a single bout of treadmill exercise SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE proprioception; immunoassay; bioassay; plasma hormones; pituitary ID SPINOHYPOTHALAMIC TRACT; SECRETION; PITUITARY; AXIS AB Plasma growth hormone (GH) measured by immunoassay [immunoassayable GH (IGH)] and by tibial bioassay [bioassayable GH (BGH)] increases in humans in response to exercise. In rats, however, IGH does not change in response to exercise. The objective of this study was to determine the BGH response to an acute exercise bout in rats. The rats ran on a treadmill at a rate of 27 m/min for 15 min, after which plasma and pituitary hormones, including IGH and BGH, and plasma metabolites were measured. Plasma and pituitary IGH were unchanged from control groups after the acute exercise bout, whereas plasma BGH was increased by 300% and pituitary BGH was decreased by 50%. Plasma thyroxine and corticosterone levels were significantly increased after a single exercise bout, but plasma testosterone, 3,5,3'-triiodothyronine, glucose, lactate, and triglyceride concentrations were unchanged. Given previous results from in situ nerve stimulation studies (Gosselink KL, Grindeland RE, Roy RR, Zhong H, Bigbee AJ, Grossman EJ, and Edgerton VR. J Appl Physiol 84: 1425-1430, 1998), these in vivo results are consistent with the rapid BGH response during exercise being induced by the activation of muscle efferents. C1 Univ Calif Los Angeles, Dept Physiol Sci, Los Angeles, CA 90095 USA. Univ Calif Los Angeles, Dept Neurobiol, Los Angeles, CA 90095 USA. Univ Calif Los Angeles, Brain Res Inst, Los Angeles, CA 90095 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Edgerton, VR (reprint author), Univ Calif Los Angeles, Dept Physiol Sci, 1804 Life Sci,405 Hilgard Ave, Los Angeles, CA 90095 USA. NR 31 TC 6 Z9 7 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD DEC PY 2000 VL 89 IS 6 BP 2174 EP 2178 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 380YZ UT WOS:000165736400010 PM 11090564 ER PT J AU Ronca, AE Alberts, JR AF Ronca, AE Alberts, JR TI Effects of prenatal spaceflight on vestibular responses in neonatal rats SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE righting reflex; otolith; labyrinth; semicircular canals; development ID RATTUS-NORVEGICUS AB Ten pregnant Norway rats (Rattus norvegicus) were flown for 11 days on board the NASA space shuttle from gestational day 9 (launch) until gestational day 20 (landing) of the rats' 22-day pregnancy. After the birth of the pups, vestibular responses were analyzed from postnatal day (P) 0 until P5. In the first test, PO neonates were supported on a platform in a side-lying position. Skyward head movements (i.e., movements performed against the gravity vector) were more frequent than head movements toward Earth in both flight and control neonates. In the second test, the contact-righting reflex, composed of stereotyped movements that rotate the body from supine to prone on a solid surface, was analyzed in PO neonates. The frequency and latency of contact-righting responses did not differ in flight and control neonates. In the third test, vestibular head righting, with tactile and proprioceptive cues removed, was tested in neonates on P1, P3, and P5 by using a water-immersion test. Righting responses were observed less frequently in P1 and P3 flight neonates compared with controls. However, this deficit was transient, as evidenced by complete response recovery on P5. Collectively, these findings provide evidence for a selective disruption of vestibular-mediated responses after prenatal exposure to spaceflight. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Indiana Univ, Dept Psychol, Bloomington, IN 47405 USA. RP Ronca, AE (reprint author), NASA, Ames Res Ctr, Div Life Sci, MS-261-3, Moffett Field, CA 94035 USA. FU NIMH NIH HHS [MH-28355, MH-46485] NR 18 TC 34 Z9 37 U1 0 U2 2 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD DEC PY 2000 VL 89 IS 6 BP 2318 EP 2324 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 380YZ UT WOS:000165736400031 PM 11090585 ER PT J AU Goodwin, TJ Coate-Li, L Linnehan, RM Hammond, TG AF Goodwin, TJ Coate-Li, L Linnehan, RM Hammond, TG TI Selected Contribution: A three-dimensional model for assessment of in vitro toxicity in Balaena mysticetus renal tissue SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Editorial Material DE bowhead whale; environmental toxicology; modeled microgravity; rotating-wall vessel; physiology ID HEAVY-METALS; SIMULATED MICROGRAVITY; MAMMALIAN-CELLS; PILOT WHALES; SHEAR-STRESS; EXPRESSION; CULTURE; COCULTURE; MERCURY; GENE AB This study established two- and three-dimensional renal proximal tubular cell cultures of the endangered species bowhead whale (Balaena mysticetus), developed SV40-transfected cultures, and cloned the 61-amino acid open reading frame for the metallothionein protein, the primary binding site for heavy metal contamination in mammals. Microgravity research, modulations in mechanical culture conditions (modeled microgravity), and shear stress have spawned innovative approaches to understanding the dynamics of cellular interactions, gene expression, and differentiation in several cellular systems. These investigations have led to the creation of ex vivo tissue models capable of serving as physiological research analogs for three-dimensional cellular interactions. These models are enabling studies in immune function, tissue modeling for basic research, and neoplasia. Three-dimensional cellular models emulate aspects of in vivo cellular architecture and physiology and may facilitate environmental toxicological studies aimed at elucidating biological functions and responses at the cellular level. Marine mammals occupy a significant ecological niche (72% of the Earth's surface is water) in terms of the potential for information on bioaccumulation and transport of terrestrial and marine environmental toxins in high-order vertebrates. Few ex vivo models of marine mammal physiology exist in vitro to accomplish the aforementioned studies. Techniques developed in this investigation, based on previous tissue modeling successes, may serve to facilitate similar research in other marine mammals. C1 NASA, Lyndon B Johnson Space Ctr, Cellular Biotechnol Program, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Wyle Labs, Life Sci Syst & Serv, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Flight Crew Operat, Houston, TX 77058 USA. Tulane Univ, Med Ctr, Environm Astrobiol Ctr, Nephrol Sect SL45, New Orleans, LA 70112 USA. Vet Adm Med Ctr, New Orleans, LA 70112 USA. RP Goodwin, TJ (reprint author), NASA, Lyndon B Johnson Space Ctr, Cellular Biotechnol Program, 2101 NASA Rd 1,Mail Code SD12, Houston, TX 77058 USA. NR 47 TC 5 Z9 5 U1 1 U2 5 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD DEC PY 2000 VL 89 IS 6 BP 2508 EP 2517 PG 10 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 380YZ UT WOS:000165736400055 PM 11090609 ER PT J AU Back, LH Banerjee, RK AF Back, LH Banerjee, RK TI Estimated flow resistance increase in a spiral human coronary artery segment SO JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID HELICAL PIPE; LAMINAR-FLOW; ATHEROSCLEROSIS; TORSION; MODEL AB Coronary flow estimates were made for a spiral coronary artery segment (identified from a post-mortem replica casting) by using a modified Dean number based on the approximate coil radius of curvature, as suggested earlier. The estimates were found to correlate experimental pressure drop data for helical coiled tubes. Over a physiological range of mean Reynolds numbers from 100 to 400 for blood flow through main coronary arteries, estimates of the flow resistance increase relative to a straight lumen segment ranged from about 20 to 80 percent, and were of similar magnitude to those found in a flow study in a sinuous coronary vessel segment with no spiral. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NIH, Bioengn & Phys Sci Program, Bethesda, MD 20892 USA. RP Back, LH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 28 TC 10 Z9 10 U1 0 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0148-0731 J9 J BIOMECH ENG-T ASME JI J. Biomech. Eng.-Trans. ASME PD DEC PY 2000 VL 122 IS 6 BP 675 EP 677 DI 10.1115/1.1319661 PG 3 WC Biophysics; Engineering, Biomedical SC Biophysics; Engineering GA 404QE UT WOS:000167111300017 PM 11192391 ER PT J AU Chiu, LS Chang, ATC AF Chiu, LS Chang, ATC TI Oceanic rain column height derived from SSM/I SO JOURNAL OF CLIMATE LA English DT Article ID PROBABILITY-DISTRIBUTION FUNCTIONS; DIURNAL CYCLE; PRECIPITATION; ERRORS; RATES AB The climatology of oceanic rain column height derived from 12 years (July 1987-June 1999) of Special Sensor Microwave Imager (SSM/I) data is presented. The estimation procedure is based on a technique developed by Wilheit et al. In the annual mean, the SSM/I-derived oceanic rain height shows a maximum of about 4.7 km in the Tropics and decreases toward the high latitudes to less than 3.5 km at 50 degrees. Interannual variations exhibit seasonal dependency and show maxima of about 200-300 m in the oceanic dry zones and in the midlatitude storm track regions. The rain heights estimated from the morning passes of the SSM/I are lower than those computed from the afternoon passes by about 60 m in the Tropics but are higher north of 40 degreesN. This small difference cannot change the conclusion about the morning maximum in rain rate. The nonsystematic error increases with decreasing rain column height and is estimated to be about 120 m for rain heights of 4-5 km and 200 m at 3.5 km. Comparison with the height of the 0 degreesC isotherm derived from the Goddard Laboratory for Atmospheres general circulation model (GCM) results shows a mean zonal low bias (SSM/I lower than GCM freezing height) of about 200 m in the Tropics. Outside the Tropics, the SSM/I rain column heights are much higher, reaching a difference of 2 km at 50 degreesN. The small bias in the Tropics is consistent with the notion that the melting layer extends over hundreds of meters below the freezing level. Outside the Tropics, the sampling of the SSM/I rain height and the inclusion of nonraining observations in GCM calculations may contribute to the large discrepancy. The freezing height is interpreted as the columnar water content and found to be consistent with columnar water vapor maps retrieved from SSM/I data. C1 George Mason Univ, Inst Computat Sci & Informat, Ctr Earth Observing & Space Res, Fairfax, VA 22030 USA. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Chiu, LS (reprint author), George Mason Univ, Inst Computat Sci & Informat, Ctr Earth Observing & Space Res, Fairfax, VA 22030 USA. EM lchiu@gmd.edu NR 24 TC 9 Z9 10 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD DEC 1 PY 2000 VL 13 IS 23 BP 4125 EP 4136 DI 10.1175/1520-0442(2000)013<4125:ORCHDF>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 382HK UT WOS:000165816700005 ER PT J AU Imaoka, K Spencer, RW AF Imaoka, K Spencer, RW TI Diurnal variation of precipitation over the tropical oceans observed by TRMM/TMI combined with SSM/I SO JOURNAL OF CLIMATE LA English DT Article ID CONVECTIVE ACTIVITY; WESTERN PACIFIC; CYCLE; RAINFALL; CIRCULATION; VARIABILITY; SATELLITE AB The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) data are used in this study as the first passive microwave information from a precessing orbit to reveal diurnal variations of precipitation over the tropical oceans (30 degreesS-30 degreesN). Data from three Special Sensor Microwave Imagers are combined to help alleviate the aliasing problem caused by the slow diurnal sampling of the TRMM satellite. Annual mean diurnal variations of rainfall in 1998 are presented for 10 degrees latitude bands and six regions. The diurnal variation over all the tropical oceans exhibits an amplitude of about +/-14% of the mean, and it peaks near dawn (approximately 0400-0700 LST). By latitude band, diurnal variation is most evident in the deep Tropics, while the ratio of the amplitude over the mean is relatively constant over most latitude bands. Other than in the early morning, there are no evident peaks exceeding the error bars for this analysis. By region, the coastal areas where the ITCZ intersects large continents and around the Maritime Continent are dominant. The morning preference of rainfall prevails almost everywhere in the open ocean where the mean rainfall is heavy, even though the amplitude is small compared to that near the continents. C1 Natl Space Dev Agcy Japan, Earth Observat Res Ctr, Minato Ku, Tokyo 1060032, Japan. NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35812 USA. RP Imaoka, K (reprint author), Natl Space Dev Agcy Japan, Earth Observat Res Ctr, Minato Ku, 1-9-9 Roppibgu, Tokyo 1060032, Japan. NR 22 TC 36 Z9 43 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD DEC 1 PY 2000 VL 13 IS 23 BP 4149 EP 4158 DI 10.1175/1520-0442(2000)013<4149:DVOPOT>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 382HK UT WOS:000165816700007 ER PT J AU Hou, AY Zhang, SQ da Silva, AM Olson, WS AF Hou, AY Zhang, SQ da Silva, AM Olson, WS TI Improving assimilated global datasets using TMI rainfall and columnar moisture observations SO JOURNAL OF CLIMATE LA English DT Article ID PHYSICAL INITIALIZATION; PRECIPITATION; ALGORITHM; PROFILES AB A global analysis that optimally combines observations from diverse sources with physical models of atmospheric and land processes can provide a comprehensive description of the climate systems. Currently, such data products contain significant errors in primary hydrological fields such as precipitation and evaporation, especially in the Tropics. In this study it is demonstrated that assimilating precipitation and total precipitable water (TPW) derived from the Tropical Rainfall Measuring Mission Microwave Imager (TMI) can significantly improve the quality of global analysis. It is shown that assimilating the 6-h averaged TMI rainfall and TPW retrievals improves not only the hydrological cycle, but also key climate parameters such as clouds, radiation, and the large-scale circulation produced by the Goddard Earth Observing System (GEOS) data assimilation system (DAS). Notably, assimilating TMI rain rates improves clouds and radiation in areas of active convection, as well as the latent heating distribution and the large-scale motion field in the Tropics, while assimilating TMI TPW retrievals leads to reduced moisture biases and improved radiative fluxes in clear-sky regions. Assimilating these data also improves the instantaneous wind and temperature fields in the analysis, leading to better short-range forecasts in the Tropics. Ensemble forecasts initialized with analyses incorporating TMI rain rates and TPW yield smaller biases in tropical precipitation forecasts beyond 1 day, better 500-hPa geopotential height forecasts up to 5 days, and better 200-hPa divergent winds up to 2 days. These results demonstrate the potential of using high quality spaceborne rainfall and moisture observations to improve the quality of assimilated global data for climate analysis and weather forecasting applications. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Data Assimilat Off, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD 21228 USA. RP Hou, AY (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. RI da Silva, Arlindo/D-6301-2012; Hou, Arthur/D-8578-2012 OI da Silva, Arlindo/0000-0002-3381-4030; NR 18 TC 20 Z9 22 U1 1 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD DEC 1 PY 2000 VL 13 IS 23 BP 4180 EP 4195 DI 10.1175/1520-0442(2000)013<4180:IAGDUT>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 382HK UT WOS:000165816700009 ER PT J AU Lewis, RM Torczon, V Trosset, MW AF Lewis, RM Torczon, V Trosset, MW TI Direct search methods: then and now SO JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS LA English DT Article DE derivative-free optimization; direct search methods; pattern search methods ID MEAD SIMPLEX-METHOD; CONVERGENCE AB We discuss direct search methods for unconstrained optimization. We give a modem perspective on this classical family of derivative-free algorithms, focusing on the development of direct search methods during their golden age from 1960 to 1971. We discuss how direct search methods are characterized by the absence of the construction of a model of the objective. We then consider a number of the classical direct search methods and discuss what research in the intervening years has uncovered about these algorithms. In particular, while the original direct search methods were consciously based on straightforward heuristics, more recent analysis has shown that in most - but not all - cases these heuristics actually suffice to ensure global convergence of at least one subsequence of the sequence of iterates to a first-order stationary point of the objective function. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. Coll William & Mary, Dept Comp Sci, Williamsburg, VA 23187 USA. Coll William & Mary, Dept Math, Williamsburg, VA 23187 USA. RP Torczon, V (reprint author), NASA, Langley Res Ctr, ICASE, Mail Stop 132C,, Hampton, VA 23681 USA. NR 31 TC 237 Z9 250 U1 3 U2 15 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-0427 J9 J COMPUT APPL MATH JI J. Comput. Appl. Math. PD DEC 1 PY 2000 VL 124 IS 1-2 BP 191 EP 207 DI 10.1016/S0377-0427(00)00423-4 PG 17 WC Mathematics, Applied SC Mathematics GA 375PT UT WOS:000165411000011 ER PT J AU Sinharoy, S Stan, MA Pal, AM Weizer, VG Smith, MA Wilt, DM Reinhardt, K AF Sinharoy, S Stan, MA Pal, AM Weizer, VG Smith, MA Wilt, DM Reinhardt, K TI MOVPE growth of lattice-mismatched Al0.88In0.12As on GaAs (100) for space solar cell applications SO JOURNAL OF CRYSTAL GROWTH LA English DT Article; Proceedings Paper CT 10th International Conference on Metalorganic Vapor Phase Epitaxy (ICMOVPE-X) CY JUN 05-09, 2000 CL HOKKAIDO UNIV, SAPPORO, JAPAN SP Japan Soc Appl Phys, Res Ctr Interface Quantum Electr, Hokkaido Univ, Asahi Glass Fdn, Casio Sci Promot Fdn, Fdn Promot Mat Sci & Technol Japan, Inoue Fdn Sci, Izumi Fdn Sci & Technol, Nippon Steel Glass Fdn Mat Sci, Ogasawara Fdn Sci & Technol, Sapporo City Int Plaza, Air Water Corp, AIXTRON AG, Daido Air Prod Electr Co Ltd, Eiko Engn Corp, EMF Ltd, EPICHEM Ltd, Furukawa Elect Corp, Hitachi Ltd, Hitachi Cable Ltd, Hitachi Plant Engn & Construct Co Ltd, Int Quantum Epitaxy Plc, Kyoto Semicond Corp, Matsushita Elect Ind Co Ltd, Mitsubishi Chem Co Ltd, MOCHEM GmbH, NEC Corp, Nichic Chem Co Ltd, Nippon Sanso Corp, NTT Bas Res Lab, Oki Elect Ind Co Ltd, Rohm Co Ltd, Sony Corp, Sumitomo Elect Ind Ltd, Toshiba Corp, Toyada Gossei Co Ltd, Ube Ind Ltd HO HOKKAIDO UNIV DE AlInAs; GaAs; MOCVD; solar cell; lattice-mismatch ID EPITAXY AB We report, for the first time, the growth and characterization of lattice-mismatched Al0.88In0.12As on GaAs (1 0 0) as part of a program to develop a high-efficiency, triple-junction space solar cell. The expected practical efficiency of this cell is 31%. The proposed triple-junction cell consists of a 2.1 -eV Al0.88In0.12As top cell, a 1.6 -eV In0.48Ga0.52As0.23P0.77 middle cell, and a 1.2 -eV In0.13Ga0.87As bottom cell. The Al0.88In0.12As layers were grown on GaAs(100) wafers cut 6 degrees off-axis. using metal organic precursors trimethylaluminum, trimethylindium and the hydride arsine in a horizontal, reduced-pressure metal organic vapor-phase epitaxy (MOVPE) reactor. Crystalline quality was evaluated through triple-axis X-ray diffractometry. Reciprocal lattice mapping showed that the Al0.88In0.12As layers were relaxed to a large extent, and were of high crystalline quality. Doping was performed using silane (n-type) and diethylzinc (p-type). Secondary ion mass spectrometry (SIMS) and electrochemical C-V profiling showed that it was possible to obtain abrupt doping profiles to the levels required for solar cell fabrication. Details of these results and those of dislocation density measurement using transmission electron microscopy (TEM) are described in this paper. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Essential Res Inc, Cleveland, OH USA. USAF, Res Lab, Kirtland AFB, NM 87117 USA. RP Sinharoy, S (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd,Mail Stop 302-1, Cleveland, OH 44135 USA. NR 10 TC 4 Z9 4 U1 1 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD DEC PY 2000 VL 221 BP 683 EP 687 DI 10.1016/S0022-0248(00)00800-9 PG 5 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 394AG UT WOS:000166501400122 ER PT J AU Ghaffarian, R AF Ghaffarian, R TI Accelerated thermal cycling and failure mechanisms for BGA and CSP assemblies SO JOURNAL OF ELECTRONIC PACKAGING LA English DT Article AB This paper reviews the accelerated thermal cycling test methods that are currently used by industry to characterize the interconnect reliability of commercial-off-the-shelf (COTS) ball grid array (BGA) and chip scale package (CSP) assemblies. Acceleration induced failure mechanisms varied from conventional surface mount (SM) failures for CSPs. Examples of unrealistic life projections for other CSPs are also presented. The cumulative cycles-to-failure for ceramic BGA assemblies performed under different conditions, including plots of their two Weibull parameters, are presented. The results are for cycles in the range of -30 degreesC to 100 degreesC, -55 degreesC to 100 degreesC, and -55 degreesC to 125 degreesC. Failure mechanisms, as well as cycles to failure for thermal shock and thermal cycling conditions in the range of -55 degreesC to 125 degreesC, were compared. Projection to other temperature cycling ranges using a modified Coffin-Manson relationship is also presented. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ghaffarian, R (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 5 TC 15 Z9 16 U1 0 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 1043-7398 J9 J ELECTRON PACKAGING JI J. Electron. Packag. PD DEC PY 2000 VL 122 IS 4 BP 335 EP 340 DI 10.1115/1.1289627 PG 6 WC Engineering, Electrical & Electronic; Engineering, Mechanical SC Engineering GA 404NZ UT WOS:000167108000009 ER PT J AU Woods, TN Tobiska, WK Rottman, GJ Worden, JR AF Woods, TN Tobiska, WK Rottman, GJ Worden, JR TI Improved solar Lyman alpha irradiance modeling from 1947 through 1999 based on UARS observations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MONITOR-SUSIM-EXPERIMENT; SPECTRAL IRRADIANCE; CHROMOSPHERIC NETWORK; QUIET SUN; ULTRAVIOLET IRRADIANCE; ACTIVE REGIONS; MAGNETIC-FLUX; RADIO FLUX; VARIABILITY; EUV AB The solar Lyman alpha radiation is the brightest solar vacuum ultraviolet (VUV: lambda < 200 nm) emission, and this radiation is deposited in Earth's atmosphere above 70 km. The Lyman irradiance and its variability are therefore important for many studies of the Earth's upper atmosphere. A long-term data set of the solar Lyman alpha irradiance from 1947 through 1999 is constructed using the measurements from the Atmospheric Explorer E (AE-E), the Solar Mesospheric Explorer (SME), and the Upper Atmosphere Research Satellite (UARS) along with predictions from proxy models to fill in data gaps and to extrapolate back to 1947. The UARS measurement is used as the reference, and the AE-E and SME measurements and the proxy models are adjusted to agree with the UARS values. The estimated I-a uncertainty for this long-term Lyman alpha time series is 10%. The average solar rotation (27-day) variability in Lyman alpha is 9% from this composite times series, and the solar rotation variability averaged over 2 years at solar minimum and maximum conditions is 5 and 11%, respectively. The average solar cycle (11-year) variability is a factor of 1.5 when the data are smoothed over 2 years, and the extreme Lyman alpha variability is a factor of 2.1. The Lyman alpha irradiances averaged over 2 years during solar minimum and maximum conditions are 3.7 and 5.6 x 10(11) photons s(-1) cm(-2), respectively. The proxy models include three components to better fit the UARS measurements; nonetheless, there remain differences between the proxy models and the observed Lyman alpha irradiance, which are related to the source of the Lyman alpha radiation being different than that for the proxies. The available proxies are primarily chromospheric and coronal emissions, whereas the Lyman alpha variability is manifested more in the transition region. It is shown that emissions throughout the chromosphere, transition region, and corona vary differently mainly because their contrasts for active network and plage components are different. A transition region proxy is needed to improve the empirical proxy models of solar irradiance, and this composite Lyman alpha time series could serve as a proxy for other transition region emissions. C1 Univ Colorado, Atmospher & Space Phys Lab, Boulder, CO 80303 USA. Fed Data Corp, Jet Prop Lab, Pasadena, CA 91109 USA. Atmospher & Environm Res Inc, Cambridge, MA 02139 USA. RP Univ Colorado, Atmospher & Space Phys Lab, 1234 Innovat Dr, Boulder, CO 80303 USA. EM tom.woods@lasp.colarado.edu NR 67 TC 218 Z9 220 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2000 VL 105 IS A12 BP 27195 EP 27215 DI 10.1029/2000JA000051 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 386BL UT WOS:000166040200011 ER PT J AU Webb, DF Lepping, RP Burlaga, LF DeForest, CE Larson, DE Martin, SF Plunkett, SP Rust, DM AF Webb, DF Lepping, RP Burlaga, LF DeForest, CE Larson, DE Martin, SF Plunkett, SP Rust, DM TI The origin and development of the May 1997 magnetic cloud SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTION; WIND SPACECRAFT; JANUARY 1997; FIELDS; PLASMA; LASCO; LOOP AB A complete halo coronal mass ejection (CME) was observed by the SOHO Large-Angle and Spectrometric Coronagraph (LASCO) coronagraphs on May 12, 1997. It was associated with activity near Sun center, implying that it was aimed earthward. Three days later on May 15 an interplanetary shock and magnetic cloud/flux rope transient was detected at the Wind spacecraft 190 R-E upstream of Earth. The long enduring southward magnetic fields associated with these structures triggered a geomagnetic storm. The CME was associated with a small coronal arcade that formed over a filament eruption with expanding double ribbons in Ha emission. The flare was accompanied by a circular EUV wave, and the arcade was flanked by adjacent dimming regions. We surmise that these latter regions marked the feet of a flux rope that expanded earthward into the solar wind and was observed as the magnetic cloud at Wind. To test this hypothesis we determined key parameters of the solar structures on May 12 and compared them with the modeled flux rope parameters at Wind on May 15. The measurements are consistent with the flux rope originating in a large coronal structure linked to the erupting filament, with the opposite-polarity feet of: the rope terminating in the depleted regions. However, bidirectional electron streaming was not observed within the cloud itself, suggesting that there is not always a good correspondence between such flows and ejecta. C1 Boston Coll, Inst Sci Res, Chestnut Hill, MA 02167 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, USRA, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Helio Res Inc, La Crescenta, CA 91214 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Stanford Univ, Ctr Space Sci & Astrophys, Stanford, CA 94305 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. AFRL, VSBS, Hanscom AFB, MA 01731 USA. Univ Space Res Assoc, Naval Res Lab, Washington, DC USA. RP Webb, DF (reprint author), Boston Coll, Inst Sci Res, Chestnut Hill, MA 02167 USA. NR 28 TC 134 Z9 135 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2000 VL 105 IS A12 BP 27251 EP 27259 DI 10.1029/2000JA000021 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 386BL UT WOS:000166040200014 ER PT J AU Shodhan, S Crooker, NU Kahler, SW Fitzenreiter, RJ Larson, DE Lepping, RP Siscoe, GL Gosling, JT AF Shodhan, S Crooker, NU Kahler, SW Fitzenreiter, RJ Larson, DE Lepping, RP Siscoe, GL Gosling, JT TI Counterstreaming electrons in magnetic clouds SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CORONAL MASS EJECTION; HEAT-FLUX DROPOUTS; SOLAR-WIND; FIELD; TOPOLOGY; RECONNECTION; EVENTS; SHOCK AB Two widely used signatures of interplanetary coronal mass ejections are counterstreaming suprathermal electrons, implying magnetic structures connected to the Sun at both ends, and magnetic clouds, characterized by large-scale field rotations, low temperature, and high field strength. In order to determine to what extent these signatures coincide, electron heat flux data were examined for 14 magnetic clouds detected by ISEE 3 and IMP 8 near solar maximum and 34 clouds detected by Wind near solar minimum. The percentage of time during each cloud passage that counterstreaming electrons were detected varied widely, from 6 clouds with essentially no counterstreaming to 8 clouds with nearly 100% counterstreaming. All of the former but less than half of the latter occurred near solar minimum, suggesting a possible solar cycle dependence on the degree of magnetic openness. The counterstreaming intervals were distributed randomly throughout the clouds, with a median length of 2.5 hours. A plot of counterstreaming percentages against cloud diameter for 33 clouds modeled as cylindrical flux ropes indicates a linear dependence of the percentage of closed flux on cloud size, with the largest clouds being the most closed. Overall the results are consistent with the view that although magnetic field lines within a magnetic cloud can form a large-scale, coherent structure, reconnection in remote regions of the structure, presumably near the Sun, sporadically alters its topology fi om closed to open until the cloud assimilates into the ambient solar wind. C1 Boston Univ, Ctr Space Phys, Boston, MA 02215 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Los Alamos Natl Lab, Grp NIS 1, Los Alamos, NM 87545 USA. USAF, Res Lab, Space Vehicles Directorate, Hanscom AFB, MA USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RP Shodhan, S (reprint author), Boston Univ, Ctr Space Phys, 725 Commonwealth Ave, Boston, MA 02215 USA. EM shodhan@.bu.edu; crooker@bu.edu; kahler@plh.af.mil; u3rjf@leprjf.gsfc.nasa.gov; davin@ssl.berkeley.edu; rpl@leprpl.gsfc.nasa.gov; siscoe@bu.edu; jgosling@lanl.gov NR 33 TC 69 Z9 70 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2000 VL 105 IS A12 BP 27261 EP 27268 DI 10.1029/2000JA000060 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 386BL UT WOS:000166040200015 ER PT J AU Skoug, RM Feldman, WC Gosling, JT McComas, DJ Reisenfeld, DB Smith, CW Lepping, RP Balogh, A AF Skoug, RM Feldman, WC Gosling, JT McComas, DJ Reisenfeld, DB Smith, CW Lepping, RP Balogh, A TI Radial variation of solar wind electrons inside a magnetic cloud observed at 1 and 5 AU SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ULYSSES OBSERVATIONS; VOYAGER 2; PLASMA; PROPAGATION; EVOLUTION; LOOP; FLUX AB The fortuitous observations of a magnetic cloud during the ACE/Ulysses radial alignment in March 1998 provide one of the first opportunities to study the same magnetic cloud at two different radial distances. In this paper, we use data from both ACE and Ulysses to examine the expansion of the cloud as well as of the adjacent noncloud solar wind. In particular, we study the evolution of the electrons as the cloud expanded from 1 to 5.4 AU, including the core, halo, and total electron populations. We find that the core and total electron temperatures at either spacecraft are moderately anticorrelated with electron density. However, combined observations from the two spacecraft show that both temperature and density decreased as the cloud expanded and thus that single point measurements cannot be used to determine a polytropic index describing the expansion of solar wind electrons within the cloud. C1 Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2BZ, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. RP Skoug, RM (reprint author), Univ Calif Los Alamos Natl Lab, MS D466, Los Alamos, NM 87545 USA. RI Reisenfeld, Daniel/F-7614-2015 NR 31 TC 30 Z9 31 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2000 VL 105 IS A12 BP 27269 EP 27275 DI 10.1029/2000JA000095 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 386BL UT WOS:000166040200016 ER PT J AU Ogilvie, KW Fitzenreiter, R Desch, M AF Ogilvie, KW Fitzenreiter, R Desch, M TI Electrons in the low-density solar wind SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID VELOCITY DISTRIBUTION-FUNCTIONS; GLOBAL PROCESSES; SPACECRAFT AB The recent occurrence of an interval (May 9-12, 1999) of abnormally low density solar wind has drawn attention to such events. The Solar Wind Experiment (SWE) instrument on the Wind spacecraft observed nine similar events between launch (November 1994) and August 1999. one in 1997, three in 1998, and five in January-August 1999. No such events were observed in 1996, the year of solar minimum. This already suggests a strong dependence upon solar activity. In this paper we discuss observations of the electron strahl, a strong anisotropy in the solar wind electrons above 60 eV directed along the magnetic field and observed continuously during th periods of low density in 1998 and 1999. When the solar wind density was less than 2 cm(-3) the angular width of the strahl was below 3.5 degrees and the temperature deduced from the slope of the electron strahl phase density (as a function of energy) in the energy range 200-800 eV was 100-150 eV, equivalent to a typical coronal electron temperature. Three examples of this phenomenon, observed on February 20-22, April 26-27, and May 9-12, 1999, are discussed to show their similarity to one another. These electron observations are interpreted to show that the strahl occurs as a result of the conservation of the first adiabatic invariant, combined with the lack of coulomb collisions as suggested by Fairfield and Scudder [1985]. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Ogilvie, KW (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, MC 690, Greenbelt, MD 20771 USA. NR 18 TC 20 Z9 20 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2000 VL 105 IS A12 BP 27277 EP 27288 DI 10.1029/2000JA000131 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 386BL UT WOS:000166040200017 ER PT J AU Berdichevsky, DB Szabo, A Lepping, RP Vinas, AF Mariani, F AF Berdichevsky, DB Szabo, A Lepping, RP Vinas, AF Mariani, F TI Interplanetary fast shocks and associated drivers observed through the 23rd solar minimum by Wind over its first 2.5 years SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RANKINE-HUGONIOT PROBLEM; CORONAL MASS EJECTIONS; ULYSSES OBSERVATIONS; MAGNETIC-FIELD; 1 AU; DISTURBANCES; 1-AU; ACCELERATION; SPACECRAFT; EVENTS AB A list of the interplanetary shocks observed by Wind from its launch tin Nov 1994) to May 1997 is presented. The magnetohydrodynamic nature of the shocks is investigated, and the associated shock parameters and their uncertainties are accurately computed using two techniques. These are: 1) a combination of the "preaveraged" magnetic-coplanarity, velocity-coplanarity, and the Abraham-Schrauner-mixed methods, and 2) the Vinas and Scudder [1986] technique for solving the nonlinear least squares Rankine-Hugoniot equations. Within acceptable limits these two techniques generally gave the same results, with some exceptions. The reasons for the exceptions are discussed. The mean strength and rate of occurrence of the shocks appear to correlate with the solar cycle. Both showed a decrease in 1996 coincident with the time of the lowest ultraviolet solar radiance, indicative of solar minimum and the beginning of solar cycle 23. Eighteen shocks appeared to be associated with corotating interaction regions (CIRs). The shock normal distribution showed a mean direction peaking in the ecliptic plane and with a longitude of similar to 200 degrees (GSE coordinates). Another 16 shocks were determined to be driven by solar transients, including magnetic clouds. These had a broader distribution of normal directions than those of the CLR cases with a mean direction close to the Sun-Earth line. Eight shocks of unknown origin had normal orientations far off the ecliptic plane. No shock propagated with longitude phi (n) greater than or equal to 220+/-10 degrees, i.e. against the average Parker spiral direction. Examination of the obliquity angle theta (Bn) (i.e., between the shock normal and the upstream interplanetary magnetic field) for the full set of shocks revealed that about 58% were quasiperpendicular, and about 32% of the shocks oblique, and the rest quasi-parallel. Small uncertainty in the estimated angle theta (Bn) was obtained for about 10 shocks with magnetosonic Mach numbers between 1 and 2. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Roma Tor Vergata, Dipartimento Fis, I-00173 Rome, Italy. RP Berdichevsky, DB (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Mail Code 690, Greenbelt, MD 20771 USA. NR 76 TC 66 Z9 67 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2000 VL 105 IS A12 BP 27289 EP 27314 DI 10.1029/1999JA000367 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 386BL UT WOS:000166040200018 ER PT J AU Denton, RE Gallagher, DL AF Denton, RE Gallagher, DL TI Determining the mass density along magnetic field lines from toroidal eigenfrequencies SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PC3 GEOMAGNETIC-PULSATIONS; ELECTRON-DENSITY; 3-4 PULSATIONS; LATITUDE; RESONANCES; IONOSPHERE; MAGNETOSPHERE; PLASMASPHERE; EIGENPERIODS; MODEL AB Toroidal eigenfrequencies can be used to remotely sense the equatorial mass density rho (eq) and the density dependence along a magnetic field line. Here we present improvements to the method of Schulz [1996], which allows rho (eq) and the power law index alpha (for mass density along a field line alpha R-alpha, where R is the radial distance from the center of the Earth) to be determined from the y intercept and slope of a plot of toroidal frequency versus toroidal harmonic number n. Our modifications include a model form for eigenfrequencies with a fractional precision of 0.0005 for -6 less than or equal to alpha less than or equal to 6 and 2 less than or equal to L less than or equal to 8 (accuracy is doubtful beyond L = 5) and an iterative procedure for getting more accurate results than those found using Schulz's method. In addition, we do an analysis of the effect of random measurement errors. Observed frequencies need to be accurate to similar to6% (3%) of the fundamental frequency in order to determine rho (eq) (alpha) to a precision of 30% (unity). We then apply our method to data generated using the Global Core Plasma Model for plasmaspheric mass density; our analysis demonstrates clearly how the alpha index represents the mass density dependence on the outer part of the held line (R/(LRE) greater than or similar to 2/3). C1 Dartmouth Coll, Dept Phys & Astron, Wilder Lab 6127, Hanover, NH 03755 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Denton, RE (reprint author), Dartmouth Coll, Dept Phys & Astron, Wilder Lab 6127, Hanover, NH 03755 USA. NR 36 TC 26 Z9 26 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2000 VL 105 IS A12 BP 27717 EP 27725 DI 10.1029/1999JA000397 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 386BL UT WOS:000166040200054 ER PT J AU Tsyganenko, NA AF Tsyganenko, NA TI Modeling the inner magnetosphere: The asymmetric ring current and Region 2 Birkeland currents revisited SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INDEPENDENT PHYSICAL PARAMETERS; LARGE-SCALE CHARACTERISTICS; MAGNETIC-FIELD MODEL; CURRENT SYSTEMS; CURRENT SHEETS; SUBSTORMS; PRESSURE; STORMS; DECAY AB A quantitative model is developed of the inner magnetospheric magnetic field, combining the effects of the azimuthally asymmetric ring current with those of held-aligned currents, due to azimuthal variation of the plasma pressure. The axisymmetric part of the model ring current was derived from average observed radial profiles of the particle pressure and anisotropy and was analytically represented by a vector potential, fitted by least squares to one derived by the Biot-Savart integral. The contribution of the asymmetric part, including the field of Birkeland currents, closed via the ionosphere, was represented as a divergenceless combination of expansions for the components of the B vector, and was also fitted by least squares to the corresponding Biot-Savart field. The total field-aligned current, associated with the noon-midnight pressure asymmetry of the outer ring current, was found to be significantly smaller than the total Region 2 current, observed at low altitudes. It is therefore concluded that most of that current is generated in the near-Earth plasma sheet. The goal of this work is a realistic and computationally efficient description of the asymmetric ring current, to be included in an advanced model of the external geomagnetic field. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Tsyganenko, NA (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Code 690-2, Greenbelt, MD 20771 USA. RI Tsyganenko, Nikolai/J-7377-2012 OI Tsyganenko, Nikolai/0000-0002-5938-1579 NR 41 TC 29 Z9 31 U1 0 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2000 VL 105 IS A12 BP 27739 EP 27754 DI 10.1029/2000JA000138 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 386BL UT WOS:000166040200056 ER PT J AU Lakhina, GS Tsurutani, BT Kojima, H Matsumoto, H AF Lakhina, GS Tsurutani, BT Kojima, H Matsumoto, H TI "Broadband" plasma waves in the boundary layers SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Review ID BAND ELECTROSTATIC NOISE; BEAM ACOUSTIC INSTABILITY; HYBRID-DRIFT INSTABILITY; LOW-FREQUENCY INSTABILITIES; ELECTRIC-FIELD STRUCTURES; JOVIAN BOW SHOCK; SHEET BOUNDARY; ION-BEAM; DAYSIDE MAGNETOPAUSE; MAGNETIC-FIELD AB Boundary layers are commonly encountered in space and astrophysical plasmas. For example, interaction of solar wind plasma with the planets and comets produces magnetopause and cometopause boundary layers, respectively. Generally, the boundary layers are formed when plasmas with different characteristics interact with each other. The plasma sheet boundary layer in the Earth's magnetotail is formed owing to the interaction of hot dense plasma in the plasma sheet region with the rarefied plasma of the lobe region. Boundary layers are the site where energy and momentum are exchanged between two distinct plasmas. Boundary layers occurring in space plasmas can support a wide spectrum of plasma waves spanning a frequency range of a few mHz to 100 kHz and beyond. The purpose of this review is to describe the main characteristics and the possible generation mechanisms of the broadband plasma waves (with frequencies of > 1 Hz) observed in the Earth's magnetopause boundary layer, the Jovian magnetopause boundary layer, the plasma sheet boundary layer, and the Earth's polar cap boundary layer. The rapid pitch angle scattering of energetic particles via cyclotron resonant interactions with the waves can provide sufficient precipitated energy flux to the ionosphere to create the dayside aurora at Earth and a weak high-latitude auroral ring at Jupiter. In general, the broadband plasma waves may play an important part in the processes of local heating/acceleration of the boundary layer plasma. Recent exciting high time resolution results on the broadband plasma waves coming from Geotail, Polar, and FAST will be discussed. C1 Indian Inst Geomagnetism, Bombay 400005, Maharashtra, India. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Kyoto Univ, Ctr Radio Atmospher Sci, Uji, Kyoto 611, Japan. RP Lakhina, GS (reprint author), Indian Inst Geomagnetism, Bombay 400005, Maharashtra, India. RI Lakhina, Gurbax /C-9295-2012; OI Lakhina, Gurbax /0000-0002-8956-486X NR 171 TC 32 Z9 32 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD DEC 1 PY 2000 VL 105 IS A12 BP 27791 EP 27831 DI 10.1029/2000JA900054 PG 41 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 386BL UT WOS:000166040200060 ER PT J AU Mehta, SK Stowe, RP Feiveson, AH Tyring, SK Pierson, DL AF Mehta, SK Stowe, RP Feiveson, AH Tyring, SK Pierson, DL TI Reactivation and shedding of cytomegalovirus in astronauts during spaceflight SO JOURNAL OF INFECTIOUS DISEASES LA English DT Article ID REPLICATION; VIRUS; IMMUNOSUPPRESSION; DEXAMETHASONE; MECHANISMS; INFECTION; IMMUNE AB The reactivation of cytomegalovirus (CMV) in 71 astronauts was investigated, using polymerase chain reaction. A significantly greater (P < .0001) shedding frequency was found in urine samples from astronauts before spaceflight (10.6%) than in urine from the healthy control subject group (1.2%). Two of 4 astronauts studied during spaceflight shed CMV in urine. A significant increase (P < .0001) in CMV antibody titer, compared with baseline values, was also found 10 days before spaceflight. CMV antibody titer was further increased (P < .001) 3 days after landing, compared with 10 days before the mission. Significant increases in stress hormones were also found after landing, These results demonstrate that CMV reactivation occurred in astronauts before spaceflight and indicate that CMV may further reactivate during spaceflight. C1 NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Lyndon B Johnson Space Ctr, Enterprise Advisory Serv, Houston, TX 77058 USA. Univ Texas, Med Branch, Dept Pathol, Galveston, TX 77550 USA. Univ Texas, Med Branch, Dept Microbiol, Galveston, TX 77550 USA. RP Pierson, DL (reprint author), NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Mail Code SD3, Houston, TX 77058 USA. OI Saenz, Henri/0000-0001-7536-7817 NR 16 TC 104 Z9 106 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0022-1899 J9 J INFECT DIS JI J. Infect. Dis. PD DEC PY 2000 VL 182 IS 6 BP 1761 EP 1764 DI 10.1086/317624 PG 4 WC Immunology; Infectious Diseases; Microbiology SC Immunology; Infectious Diseases; Microbiology GA 378QY UT WOS:000165596100024 PM 11069250 ER PT J AU Mendez, AJ Gagliardi, RM Feng, HXC Heritage, JP Morookian, JM AF Mendez, AJ Gagliardi, RM Feng, HXC Heritage, JP Morookian, JM TI Strategies for realizing optical CDMA for dense, high-speed, long span, optical network applications SO JOURNAL OF LIGHTWAVE TECHNOLOGY LA English DT Article DE access protocols; code division multiaccess; codes; encoding; multiaccess communication; optical fiber communication; optical fiber dispersion; propagation ID ULTRASHORT LIGHT-PULSE; FIBER; SYSTEMS; TRANSMISSION AB Since the mid 1990s, the role of optical CDMA has expanded from local area networks to longer span, telecommunication-type networks. In order to play a significant role in these longer span, denser, higher data rate networks, optical CDMA code set must 1) have at least as many codes as dense wavelength division multiplexing (WDM) (i.e., more than eight codes); 2) operate at high data rates (i.e., greater than 2.5 Gb/s); and 3) propagate with high fidelity over the installed or installable fiber links. Most approaches to optical CDMA require narrow pulses, which are more susceptible to fiber impairments and may have lower spectral efficiency than conventional WDM modulation schemes such as nonreturn-to-zero (NRZ), so they do not meet these new requirements. Therefore, we have formulated a strategy which simultaneously increases the number of good codes (resulting in higher density) and reduces their code length (i.e., decreasing the number of time slots required thus enabling higher data rates for a given chip time): the strategy of matrix codes. In this paper, we describe the design of a set of eight matrix codes for operation at 2.5 Gb/s and evaluate their propagation over an existing 214 km network link by means of computer simulation, The results indicate that the codes propagate well if dispersion management is used. The paper also discusses a strategy for managing the multiaccess interference (MAI) in a bursty traffic environment. C1 MRDA, El Segundo, CA 90245 USA. Univ So Calif, Los Angeles, CA 90089 USA. Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. Univ Calif Davis, Davis, CA 95616 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mendez, AJ (reprint author), MRDA, El Segundo, CA 90245 USA. NR 28 TC 52 Z9 55 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0733-8724 J9 J LIGHTWAVE TECHNOL JI J. Lightwave Technol. PD DEC PY 2000 VL 18 IS 12 BP 1685 EP 1696 DI 10.1109/50.908693 PG 12 WC Engineering, Electrical & Electronic; Optics; Telecommunications SC Engineering; Optics; Telecommunications GA 410JZ UT WOS:000167438000009 ER PT J AU Barmatz, M Hahn, I Zhong, F Anisimov, MA Agayan, VA AF Barmatz, M Hahn, I Zhong, F Anisimov, MA Agayan, VA TI Crossover analyses of heat capacity and susceptibility measurements near the He-3 liquid-gas critical point SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT International Symposium on Quantum Fluids and Solids (QFS 2000) CY JUN 06-11, 2000 CL MINNEAPOLIS, MN SP Int Union Pure & Appl Phys, Natl Aeronaut & Space Administrat, Jet Propuls Lab, Univ Minnesota, Theoret Phys Inst, Minnesota Supercomp Inst, Digital Simulat & Adv Computat, Natl Sci Fdn, Div Mat Res, Univ Minnesota, Sch Phys & Astronomy, Univ Minnesota, Inst Technol, Univ Minnesota, Off Vice President Res Dean Grad Sch, Univ Minnesota, Off Provost & Execut Vice President, Andeen Hagerling Inc, Keithley Instrument Inc, Lakeshore Cryotron Inc, Oxford Instruments Inc ID NONASYMPTOTIC CRITICAL-BEHAVIOR; VAPOR CRITICAL-POINT; RENORMALIZATION GROUP; CRITICAL EXPONENTS; 3 DIMENSIONS; FIELD-THEORY; FLUIDS; MODELS AB An experiment called MISTE (Microgravity Scaling Theory Experiment) is being developed for a future mission on the International Space Station. The main objective of this flight experiment is to perform in-situ PVT, heat capacity at constant volume, C-V, and isothermal susceptibility, chi (T), measurements in the asymptotic region of the He-3 liquid-gas critical point. On the ground, gravity induces a density gradient that does not permit an accurate test of theoretical predictions within the asymptotic region. In preparation for this flight experiment, precision ground-based measurements are now being performed in the crossover region away from the critical point to determine the crossover parameters. Recent C-V and chi (T) measurements along the critical isochore have been analyzed using a new crossover parametric equation-of-state and a field theoretical Renormalization Group calculation based upon the phi (4) model. A description of the experimental techniques and preliminary results of the theoretical analyses will be presented. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM barmatz@squid.jpl.nasa.gov NR 24 TC 12 Z9 12 U1 0 U2 0 PU SPRINGER/PLENUM PUBLISHERS PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2291 EI 1573-7357 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD DEC PY 2000 VL 121 IS 5-6 BP 633 EP 642 DI 10.1023/A:1017527930590 PG 10 WC Physics, Applied; Physics, Condensed Matter SC Physics GA 403FF UT WOS:000167031400062 ER PT J AU Duncan, RV Babkin, AV Sergatskov, DA Boyd, STP McCarson, TD Day, PK AF Duncan, RV Babkin, AV Sergatskov, DA Boyd, STP McCarson, TD Day, PK TI Decoherence under a heat flux near the superfluid transition in He-4 SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT International Symposium on Quantum Fluids and Solids (QFS 2000) CY JUN 06-11, 2000 CL MINNEAPOLIS, MINNESOTA SP Int Union Pure & Appl Phys, Natl Aeronaut & Space Administrat, Jet Propuls Lab, Univ Minnesota, Theoret Phys Inst, Minnesota Supercomp Inst, Digital Simulat & Adv Computat, Natl Sci Fdn, Div Mat Res, Univ Minnesota, Sch Phys & Astronomy, Univ Minnesota, Inst Technol, Univ Minnesota, Off Vice President Res Dean Graduate Sch, Univ Minesota, Off Provost & Execut Vice President, Andeen Hagerling Inc, Keithley Instrument Inc, Lakeshore Cryotron Inc, Oxford Instruments Inc ID THERMAL TRANSPORT-PROPERTIES; SELF-ORGANIZED CRITICALITY; LAMBDA-POINT; TEMPERATURE-MEASUREMENT; HE-3-HE-4 MIXTURES; HELIUM-II; T-LAMBDA; CAPACITY; DEPRESSION; PHASE AB Measurements of heat transport at the transition from perfect thermal super-conductively to nonlinear heat diffusion in pure He-4 provide a very sensitive probe of matter wave coherence. Superfluid heat transport is proportional to the product of the superfluid density and the superfluid velocity, which are both directly related to the superfluid order parameter. From dynamic scaling theory, the correlation length near the superfluid transition provides a measure of the length over which phase fluctuations of the order parameter persist. Our measurements; suggest that both the hydrostatic pressure variation within the liquid helium column, together with the heat flux Q, limit the otherwise divergent correlation length near the superfluid transition. Future measurements planned for the microgravity laboratory will provide the first extensive experimental test of a renormalized, field theoretic description of heat transport near the superfluid transition. It will also provide a conclusive experimental study Of the influence of hydrostatic pressure effects and dynamical effects on the correlation length. A new class of microgravity experiments is proposed that will permit measurements to within 10 pK of the superfluid transition temperature, allowing an entirely new class of ultra-accurate scientific investigations to be performed. C1 Univ New Mexico, Albuquerque, NM 87131 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Duncan, RV (reprint author), Univ New Mexico, 800 Yale Blvd NE, Albuquerque, NM 87131 USA. NR 37 TC 2 Z9 2 U1 0 U2 2 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD DEC PY 2000 VL 121 IS 5-6 BP 643 EP 652 DI 10.1023/A:1017579914660 PG 10 WC Physics, Applied; Physics, Condensed Matter SC Physics GA 403FF UT WOS:000167031400063 ER PT J AU Larson, M Panek, J Nash, A Mulders, N AF Larson, M Panek, J Nash, A Mulders, N TI Capacitative detection of phase separation in He-3-He-4 mixtures near the tricritical point SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT International Symposium on Quantum Fluids and Solids (QFS 2000) CY JUN 06-11, 2000 CL MINNEAPOLIS, MINNESOTA SP Int Union Pure & Appl Phys, Natl Aeronaut & Space Administrat, Jet Propuls Lab, Univ Minnesota, Theoret Phys Inst, Minnesota Supercomp Inst, Digital Simulat & Adv Computat, Natl Sci Fdn, Div Mat Res, Univ Minnesota, Sch Phys & Astronomy, Univ Minnesota, Inst Technol, Univ Minnesota, Off Vice President Res Dean Graduate Sch, Univ Minesota, Off Provost & Execut Vice President, Andeen Hagerling Inc, Keithley Instrument Inc, Lakeshore Cryotron Inc, Oxford Instruments Inc AB We have used two different types of capacitative sensors for detecting the phase separation boundary in He-3-He-4 mixtures es. We have used a parallel plate geometry to make bulk concentration measurements, and we have developed inter-digital capacitors (IDC's) to make local concentration measurements. The IDC's were developed as part of our on going effort to study the tricritical point in the absence of acceleration. The IDC's should be well suited for making measurements of the phase separation on the He-3 rich side of the phase diagram where the minority He-4 rich phase will grow out from the walls. The resolution and advantages of these two types of sensors are presented below along with preliminary ground based measurements of the phase separation boundary taken with the IDC's. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA. RP Larson, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 8 TC 3 Z9 3 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD DEC PY 2000 VL 121 IS 5-6 BP 653 EP 658 DI 10.1023/A:1017532031498 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA 403FF UT WOS:000167031400064 ER PT J AU Sukhatme, K Mukharsky, Y Chui, T Pearson, D AF Sukhatme, K Mukharsky, Y Chui, T Pearson, D TI Measurements of critical current of superfluid He-4 through an array of submicron apertures very near T-lambda SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT International Symposium on Quantum Fluids and Solids (QFS 2000) CY JUN 06-11, 2000 CL MINNEAPOLIS, MINNESOTA SP Int Union Pure & Appl Phys, Natl Aeronaut & Space Administrat, Jet Propuls Lab, Univ Minnesota, Theoret Phys Inst, Minnesota Supercomp Inst, Digital Simulat & Adv Computat, Natl Sci Fdn, Div Mat Res, Univ Minnesota, Sch Phys & Astronomy, Univ Minnesota, Inst Technol, Univ Minnesota, Off Vice President Res Dean Graduate Sch, Univ Minesota, Off Provost & Execut Vice President, Andeen Hagerling Inc, Keithley Instrument Inc, Lakeshore Cryotron Inc, Oxford Instruments Inc ID FLOW AB Far from the lambda transition the critical flow of superfluid He-4 through a small orifice is determined by thermal nucleation of quantized vortices. Between 300 mK and 2 K linearly decreasing critical flow velocity has been observed earlier. As the temperature approaches T-lambda the size of the vortex core increases and becomes comparable to that of the orifice. We report here measurements of the critical mass current in this temperature range. An array of 24 3 x 0.17 mum holes in parallel with a macroscopic parallel path and flexible-diaphragm Helmholtz resonator have been used. The temperature range explored was from approximate to 80 mK to approximate to 20 muK below T-lambda. Preliminary analysis of the data shows that for a reduced temperature t = (T-lambda - T)/T-lambda greater than or similar to1 . 10(-4) the critical current scales approximately as t(1.25). Closer to Tx the critical phase difference across the array becomes comparable to 2 pi and the results have to be analyzed in terms of Josephson effect. The superfluid density has been measured at the same time as the critical current. C1 CALTECH, Jet Prop Lab, Pasadena, CA USA. Ctr Estud Saclay, Serv Phys Etat Condense, DRECAM, CEA, F-91191 Gif Sur Yvette, France. RP Sukhatme, K (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA USA. RI Mukharsky, Yury/F-4920-2013 NR 11 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD DEC PY 2000 VL 121 IS 5-6 BP 665 EP 670 DI 10.1023/A:1017536132407 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA 403FF UT WOS:000167031400066 ER PT J AU Mohazzab, M Mulders, N Nash, A Larson, M AF Mohazzab, M Mulders, N Nash, A Larson, M TI Tantalum thin-film superconducting transition edge thermometers SO JOURNAL OF LOW TEMPERATURE PHYSICS LA English DT Article; Proceedings Paper CT International Symposium on Quantum Fluids and Solids (QFS 2000) CY JUN 06-11, 2000 CL MINNEAPOLIS, MINNESOTA SP Int Union Pure & Appl Phys, Natl Aeronaut & Space Administrat, Jet Propuls Lab, Univ Minnesota, Theoret Phys Inst, Minnesota Supercomp Inst, Digital Simulat & Adv Computat, Natl Sci Fdn, Div Mat Res, Univ Minnesota, Sch Phys & Astronomy, Univ Minnesota, Inst Technol, Univ Minnesota, Off Vice President Res Dean Graduate Sch, Univ Minesota, Off Provost & Execut Vice President, Andeen Hagerling Inc, Keithley Instrument Inc, Lakeshore Cryotron Inc, Oxford Instruments Inc AB Sputter deposited Ta thin films make excellent superconducting transition edge temperature sensors. Depending on film thickness, their transition temperature, Tc, ranges from 4.4K to as least as low as 0.5K. A figure of merit of 50K(-1) is easily achieved. The films are mechanically extremely strong, and at room temperature show minimal aging. Using a simple heat treatment technique, T-c can be tuned to the desired operating range. C1 Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mohazzab, M (reprint author), Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA. NR 1 TC 6 Z9 6 U1 1 U2 4 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2291 J9 J LOW TEMP PHYS JI J. Low Temp. Phys. PD DEC PY 2000 VL 121 IS 5-6 BP 821 EP 824 DI 10.1023/A:1017589611451 PG 4 WC Physics, Applied; Physics, Condensed Matter SC Physics GA 403FF UT WOS:000167031400092 ER PT J AU Snyder, GJ Caillat, T Fleurial, JP AF Snyder, GJ Caillat, T Fleurial, JP TI Thermoelectric properties of the incommensurate layered semiconductor GexNbTe2 SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID SEEBECK AB The compounds GexNbTe2 (0.39 less than or equal to x less than or equal to 0.53) have been studied for their thermoelectric properties. By changing x the carrier concentration can be adjusted so that the material changes from a p-type metal to a p-type semiconductor. The maximum germanium concentration at about Ge0.5NbTe2 is also the most semiconducting composition. High- and low-temperature electrical resistivity, Hall effect, Set beck coefficient, and thermal conductivity were measured. Evidence of electronic ordering was found in some samples. The thermal conductivity is reasonably low and glasslike with room temperature values around 20-25 mW/cm K. However, the power factor is too low to compete with state-of-the-art materials. The maximum thermoelectric figure of merit, ZT found in these compounds is about 0.12. The low ZT can be traced to the low carrier mobility of about 10 cm(2)/Ns. The related compounds Si0.5NbTe2 and Ge0.5TaTe2 were also studied. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Snyder, GJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 277-207, Pasadena, CA 91109 USA. RI Snyder, G. Jeffrey/E-4453-2011; Snyder, G/I-2263-2015 OI Snyder, G. Jeffrey/0000-0003-1414-8682; NR 8 TC 1 Z9 1 U1 0 U2 3 PU MATERIALS RESEARCH SOCIETY PI WARRENDALE PA 506 KEYSTONE DR, WARRENDALE, PA 15086 USA SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD DEC PY 2000 VL 15 IS 12 BP 2789 EP 2793 DI 10.1557/JMR.2000.0398 PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA 381CZ UT WOS:000165745900031 ER PT J AU Nicholson, LM Whitley, KS Gates, TS Hinkley, JA AF Nicholson, LM Whitley, KS Gates, TS Hinkley, JA TI Influence of molecular weight on the mechanical performance of a thermoplastic glassy polyimide SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID POLY(METHYL METHACRYLATE); FRACTURE; COMPOSITES; POLYMERS; FILMS AB Mechanical testing of an advanced thermoplastic polyimide (LaRC(TM)-SI) with known variations in molecular weight was performed over a range of temperatures below the glass transition temperature. The physical characterization, elastic properties and notched tensile strength were all determined as a function of molecular weight and test temperature. It was shown that notched tensile strength is a strong function of both temperature and molecular weight, whereas stiffness is only a strong function of temperature. A critical molecular weight (M-c) was observed to occur at a weight-average molecular weight ((M) over bar (w)) of similar to 22000 g/mol below which, the notched tensile strength decreases rapidly. This critical molecular weight transition is temperature-independent. Furthermore, inelastic analysis showed that low molecular weight materials tended to fail in a brittle manner, whereas high molecular weight materials exhibited ductile failure. The microstructural images supported these findings. (C) 2000 Kluwer Academic Publishers. C1 NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Appl Mat & Proc Branch, Hampton, VA 23681 USA. RP Gates, TS (reprint author), NASA, Langley Res Ctr, Mech & Durabil Branch, MS 188E,2 W Reid St, Hampton, VA 23681 USA. NR 35 TC 11 Z9 11 U1 0 U2 7 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD DEC PY 2000 VL 35 IS 24 BP 6111 EP 6121 DI 10.1023/A:1026788002167 PG 11 WC Materials Science, Multidisciplinary SC Materials Science GA 393BG UT WOS:000166448800007 ER PT J AU Salem, JA Jenkins, MG Keller, DJ AF Salem, JA Jenkins, MG Keller, DJ TI Estimating standard deviations of fatigue parameters for ceramics exhibiting slow crack growth SO JOURNAL OF MATERIALS SCIENCE LETTERS LA English DT Article C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Washington, Dept Mech Engn, Seattle, WA 98195 USA. RealWorld Qual Syst Inc, Rocky River, OH 44116 USA. RP Salem, JA (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 10 TC 3 Z9 3 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0261-8028 J9 J MATER SCI LETT JI J. Mater. Sci. Lett. PD DEC PY 2000 VL 19 IS 24 BP 2213 EP 2214 DI 10.1023/A:1006704319570 PG 2 WC Materials Science, Multidisciplinary SC Materials Science GA 391MJ UT WOS:000166359500013 ER PT J AU Tunstel, EW AF Tunstel, EW TI Commentary on "The nature of distributed learning and remembering" SO JOURNAL OF MIND AND BEHAVIOR LA English DT Editorial Material AB This exposition (Iran-Nejad and Homaifar, 2000) offers a compelling argument for biofunctional cognition, which suggests that functional properties of the brain, as inferred from empirical findings, be used as a basis for examining the nature of distributed learning and remembering (DLR). Undoubtedly, cognitive models that are compatible with observed phenomena will contribute to a more complete understanding of the nature of DLR. Notwithstanding the contrasts and incompatibilities between connectionist and biofunctional models stressed by the authors, we can learn from each class of models. The issue of how to realize the latter to enable empirical investigations still remains to he addressed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tunstel, EW (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 INST MIND BEHAVIOR INC PI NEW YORK PA PO BOX 522 VILLAGE STATION, NEW YORK, NY 10014 USA SN 0271-0137 J9 J MIND BEHAV JI J. Mind Behav. PD WIN-SPR PY 2000 VL 21 IS 1-2 BP 185 EP 187 PG 3 WC Psychology, Multidisciplinary; Psychology, Experimental SC Psychology GA 336LV UT WOS:000088304300015 ER PT J AU Cassell, AM Meyyappan, M Han, J AF Cassell, Alan M. Meyyappan, M. Han, Jie TI Multilayer film assembly of carbon nanotubes SO JOURNAL OF NANOPARTICLE RESEARCH LA English DT Article DE carbon nanotube; chemical vapor deposition; multilayer assembly AB An approach to assemble multilayers of carbon nanotubes on a substrate is presented. Chemical vapor deposition using a transition metal catalyst formulation is used to grow the nanotubes. Results show a bilayer assembly of nanotubes each with a different density of tubes. C1 [Cassell, Alan M.; Han, Jie] ELORET Corp, Sunnyvale, CA USA. [Meyyappan, M.] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Cassell, AM (reprint author), ELORET Corp, Sunnyvale, CA USA. EM acassell@mail.arc.nasa.gov FU NASA FX This work was supported by the NASA Ames Nanotechnology Program. The authors acknowledge the technical support of Sunita Verma. NR 10 TC 6 Z9 6 U1 1 U2 2 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 1388-0764 J9 J NANOPART RES JI J. Nanopart. Res. PD DEC PY 2000 VL 2 IS 4 BP 387 EP 389 DI 10.1023/A:1010026608660 PG 3 WC Chemistry, Multidisciplinary; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary SC Chemistry; Science & Technology - Other Topics; Materials Science GA V19IZ UT WOS:000208067400007 ER PT J AU Lewinsohn, CA Singh, M Shibayama, T Hinoki, T Ando, M Katoh, Y Kohyama, A AF Lewinsohn, CA Singh, M Shibayama, T Hinoki, T Ando, M Katoh, Y Kohyama, A TI Joining of silicon carbide composites for fusion energy applications SO JOURNAL OF NUCLEAR MATERIALS LA English DT Article; Proceedings Paper CT 9th International Conference on Fusion Reactor Materials (ICFRM-9) CY OCT 10-15, 1999 CL COLORADO SPRINGS, COLORADO SP US DOE, Off Fus Energy Sci, Argoone Natl Lab, Oak Ridge Natl Lab, Pacific NW Natl Lab, Univ Calif Santa Barbara, Amer Nucl Soc, Min Met & Mat Soc ID CERAMICS AB Joining of silicon carbide based materials has been recognized as one of the enabling technologies for the successful utilization of ceramic components in fusion energy systems. Sintered silicon carbide (Hexoloy SA) and silicon carbide (Hi-Nicalon(TM)) fiber reinforced silicon carbide matrix composites have been joined using reaction forming/bonding based joining technologies. The room- and high-temperature mechanical properties and fractography of ceramic joints have been reported. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Pacific NW Natl Lab, MSIN, Richland, WA 99352 USA. NASA, Glen Res Ctr, Cleveland, OH 44135 USA. Hokkaido Univ, Ctr Adv Res Energy Technol, Sapporo, Hokkaido, Japan. Kyoto Univ, Inst Adv Energy, Uji, Kyoto 611, Japan. RP Lewinsohn, CA (reprint author), Pacific NW Natl Lab, MSIN, P8-15,POB 999, Richland, WA 99352 USA. RI Shibayama, Tamaki/F-7586-2012; OI Katoh, Yutai/0000-0001-9494-5862 NR 13 TC 28 Z9 29 U1 1 U2 10 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-3115 J9 J NUCL MATER JI J. Nucl. Mater. PD DEC PY 2000 VL 283 BP 1258 EP 1261 DI 10.1016/S0022-3115(00)00247-6 PN B PG 4 WC Materials Science, Multidisciplinary; Nuclear Science & Technology SC Materials Science; Nuclear Science & Technology GA 383HV UT WOS:000165877800108 ER PT J AU Blake, R Khanbilvardi, R Rosenzweig, C AF Blake, R Khanbilvardi, R Rosenzweig, C TI "Climate change impacts on New York City's water supply system" - Reply to discussion by David C. Major SO JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION LA English DT Editorial Material C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. CUNY City Coll, Ctr Water Resources & Envronm Res, New York, NY 10031 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Blake, R (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER WATER RESOURCES ASSOC PI MIDDLEBURG PA 4 WEST FEDERAL ST, PO BOX 1626, MIDDLEBURG, VA 20118-1626 USA SN 1093-474X J9 J AM WATER RESOUR AS JI J. Am. Water Resour. Assoc. PD DEC PY 2000 VL 36 IS 6 BP 1445 EP 1445 DI 10.1111/j.1752-1688.2000.tb05743.x PG 1 WC Engineering, Environmental; Geosciences, Multidisciplinary; Water Resources SC Engineering; Geology; Water Resources GA 391LP UT WOS:000166357700023 ER PT J AU Martinez-Fernandez, J Morscher, GN AF Martinez-Fernandez, J Morscher, GN TI Room and elevated temperature tensile properties of single tow Hi-Nicalon, carbon interphase, CVISiC matrix minicomposites SO JOURNAL OF THE EUROPEAN CERAMIC SOCIETY LA English DT Article DE C-interphase; composites; mechanical properties; SiC-SiC; SiC fibres ID STRESS-RUPTURE; MECHANICAL-PROPERTIES; BORON-NITRIDE; COMPOSITES; OXIDATION; KINETICS; AIR AB Single tow Hi-Nicalon(TM), C interphase, CVI SiC matrix minicomposites were tested in tension at room temperature, 700, 950, and 1200 degreesC in air. Monotonic loading with modal acoustic emission monitoring was performed at room temperature in order to determine the dependence of matrix cracking on applied load. Modal acoustic emission was shown to correlate directly with the number of matrix cracks formed. Elevated temperature constant load stress-rupture and low-cycle fatigue experiments were performed on precracked specimens. The elevated temperature rupture behavior was dependent on the precrack stress, the lower precrack stress resulting in longer rupture life for a given stress. It was found that the rupture lives of C-interphase Hi-Nicalon(TM) minicomposites were superior to C-interphase Ceramic Grade Nicalon(TM) minicomposites and inferior to those of BN-interphase Hi-Nicalon(TM) minicomposites. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Glenn Res Ctr, Ohio Aerosp Inst, Cleveland, OH 44135 USA. Univ Sevilla, Dept Fis Mat Condensada, Seville, Spain. RP Morscher, GN (reprint author), NASA, Glenn Res Ctr, Ohio Aerosp Inst, MS 106-5, Cleveland, OH 44135 USA. RI MARTINEZ FERNANDEZ, JULIAN/K-1826-2012 OI MARTINEZ FERNANDEZ, JULIAN/0000-0002-1199-6638 NR 22 TC 15 Z9 15 U1 2 U2 11 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0955-2219 J9 J EUR CERAM SOC JI J. European Ceram. Soc. PD DEC PY 2000 VL 20 IS 14-15 BP 2627 EP 2636 DI 10.1016/S0955-2219(00)00138-2 PG 10 WC Materials Science, Ceramics SC Materials Science GA 377CH UT WOS:000165494000040 ER PT J AU Fernandez, JM Munoz, A Varela-Feria, FM Singh, M AF Fernandez, JM Munoz, A Varela-Feria, FM Singh, M TI Interfacial and thermomechanical characterization of reaction formed joints in silicon carbide-based materials SO JOURNAL OF THE EUROPEAN CERAMIC SOCIETY LA English DT Article DE interfaces; joining; mechanical properties; microstructure-final; SiC ID DAMAGE-ENHANCED CREEP; CERAMICS; DEFORMATION; MECHANISMS; BEHAVIOR AB The microstructure and mechanical properties of reaction formed joints of Refel(TM) reaction bonded SiC (RB-SiC) and Hexoloy(TM) sintered SiC were studied in order to achieve a better understanding of the influence of base materials and joining process parameters on the high temperature strength of reaction formed joints. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and optical microscopy were used to characterize the joints prior to mechanical tests. The microstructural analysis indicated that the joints consist of silicon carbide (SiC) grains (with grain sizes ranging from 0.1 to 2 mum) and crystalline silicon as an intergranular phase. Most of the silicon carbide grains in the joint have hexagonal crystal structure with certain preferential orientations related to the silicon matrix. The high temperature strength of joints was measured by constant strain rate experiments in compression where joints were forming 45 degrees with the compression axe. The strength of the joined Refel RB-SiC has been found to be at least equal to that of the bulk materials (550 MPa at 1235 degreesC and 400 MPa at 1385 degreesC). The joined Hexoloy specimens had strengths (1.4 GPa at 1290 degreesC and 750 MPa at 1420 degreesC) lower than the bulk material but higher than the joints of RB-SiC. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Sevilla, Dept Fis Mat Condensada, Seville, Spain. NASA, Glenn Res Ctr, Ceram Branch, Cleveland, OH 44135 USA. RP Fernandez, JM (reprint author), Univ Sevilla, Dept Fis Mat Condensada, Apdo 1065, Seville, Spain. RI MARTINEZ FERNANDEZ, JULIAN/K-1826-2012 OI MARTINEZ FERNANDEZ, JULIAN/0000-0002-1199-6638 NR 23 TC 19 Z9 20 U1 0 U2 7 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0955-2219 J9 J EUR CERAM SOC JI J. European Ceram. Soc. PD DEC PY 2000 VL 20 IS 14-15 BP 2641 EP 2648 PG 8 WC Materials Science, Ceramics SC Materials Science GA 377CH UT WOS:000165494000042 ER PT J AU Nemeth, MP AF Nemeth, MP TI Buckling behavior of long anisotropic plates subjected to restrained thermal expansion and mechanical loads SO JOURNAL OF THERMAL STRESSES LA English DT Article ID LAMINATED COMPOSITE PLATES; SHEAR DEFORMATION; OPTIMAL-DESIGN; TEMPERATURE; COMPRESSION; FIELD AB An approach for synthesizing buckling results and behavior for thin balanced and unbalanced symmetric laminates that are subjected to nondestabilizing mechanical preloads, uniform heating or cooling, and elastically or totally restrained axial thermal expansion or contraction is presented. This approach uses a nondimensional analysis for infinitely long, flexurally anisotropic plates that are subjected to combined loads and is based on useful nondimensional parameters. In addition, a stiffness-weighted laminate coefficient of thermal expansion is derived and used to determine critical temperatures in terms of physically intuitive mechanical buckling coefficients, and the effects of membrane orthotropy and membrane anisotropy are included. Many results are presented for some common laminates that are intended to facilitate a structural designer's transition to the use of the generic buckling design curves that are presented in the article. Several generic buckling design curves are presented that provide physical insight into the buckling response in addition to providing useful design data. Examples are presented that demonstrate the use of the generic design curves. The analysis approach and generic results identify the effects and characteristics of laminate thermal expansion, membrane orthotropy and anisotropy, and flexural orthotropy and anisotropy in a very general and unifying manner. C1 NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. RP Nemeth, MP (reprint author), NASA, Langley Res Ctr, Mech & Durabil Branch, Hampton, VA 23681 USA. NR 42 TC 8 Z9 8 U1 0 U2 1 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0149-5739 J9 J THERM STRESSES JI J. Therm. Stresses PD DEC PY 2000 VL 23 IS 9 BP 873 EP 916 DI 10.1080/014957300750040122 PG 44 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA 378PV UT WOS:000165593500004 ER PT J AU Kalfoglou, Y Menzies, T Althoff, KD Motta, E AF Kalfoglou, Y Menzies, T Althoff, KD Motta, E TI Meta-knowledge in systems design: panacea ... or undelivered promise? SO KNOWLEDGE ENGINEERING REVIEW LA English DT Review DE ontologies; problem-solving methods; experienceware; patterns; design types; cost-effective analysis ID ONTOLOGIES; TASK; PRINCIPLES; PROJECT; LEVEL AB In this study we present a review of the emerging field of meta-knowledge components as practised over the past decade among a variety of practitioners. We use the artificially defined term "meta-knowledge" to encompass all those different but overlapping notions used by the artificial intelligence and software engineering communities to represent reusable modelling frameworks: ontologies, problem-solving methods, patterns and experience factories and bases, to name but a few. We then elaborate on how meta-knowledge is deployed in the context of system's design to improve its reliability by consistency-checking, enhance its reuse potential and manage its knowledge-sharing. We speculate on its usefulness and explore technologies for supporting deployment of meta-knowledge. We argue that, despite the different approaches being followed in systems design by divergent communities, meta-knowledge is present in all cases. in a tacit or explicit form, and its utilisation depends on pragmatic aspects which we try to identify and critically review on criteria of effectiveness. C1 Open Univ, Knowledge Media Inst, Milton Keynes MK7 6AA, Bucks, England. NASA, WVU, Software Res Lab, Fairmont, WV USA. Fraunhofer Inst Expt Software Engn, Kaiserslautern, Germany. RP Open Univ, Knowledge Media Inst, Walton Hall, Milton Keynes MK7 6AA, Bucks, England. EM yannisk@dai.ed.ac.uk; tim@menzies.com; dieter.altho@iese.fhg.de; e.motta@open.ac.uk OI Motta, Enrico/0000-0003-0015-1952 NR 108 TC 5 Z9 5 U1 1 U2 2 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0269-8889 EI 1469-8005 J9 KNOWL ENG REV JI Knowl. Eng. Rev. PD DEC PY 2000 VL 15 IS 4 BP 381 EP 404 PG 24 WC Computer Science, Artificial Intelligence SC Computer Science GA 446CF UT WOS:000169494800004 ER PT J AU Phipps, CR Reilly, JP Campbell, JW AF Phipps, CR Reilly, JP Campbell, JW TI Optimum parameters for laser launching objects into low Earth orbit SO LASER AND PARTICLE BEAMS LA English DT Article ID STIMULATED RAMAN-SCATTERING; RADIATION; H-2; ABLATION; VACUUM; ALLOYS; N-2 AB We derive optimum values of parameters for laser-driven flights into low Earth orbit (LEO) using an Earth-based laser, as well as sensitivity to variations from the optima. These parameters are the ablation plasma exhaust velocity u(E) and specific ablation energy Q*, plus related quantities such as momentum coupling coefficient C-m and the pulsed or continuous laser intensity that must be delivered to the ablator to produce these values. Different optima are found depending upon whether it is desired to maximize mass m delivered to LEG, maximize the ratio m/M of orbit to ground mass, or minimize cost in energy per gram delivered. Although it is not within the scope of this report to provide an engineered flyer design, a notional, cone-shaped flyer is described to provide a substrate for the discussion and flight simulations. The flyer design emphasizes conceptually and physically separate functions of light collection at a distance from the laser source, light concentration on the ablator, and autonomous steering. Approximately ideal flight paths to LEO are illustrated beginning from an elevated platform. We believe LEO launch costs can be reduced 100-fold in this way. Sounding rocket cases, where the only goal is to momentarily reach a certain altitude starting from near sea level, are also discussed. Nonlinear optical constraints on laser propagation through the atmosphere to the flyer are briefly considered. C1 Photon Associates, Santa Fe, NM 87505 USA. NE Sci & Technol, E Sandwich, MA 02537 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Phipps, CR (reprint author), Photon Associates, 200A Ojo Vaca Rd, Santa Fe, NM 87505 USA. EM CRPhipps@aol.com RI Kotkov, Andrei/K-7590-2015; Selenev, Leonid/K-7441-2015 OI Kotkov, Andrei/0000-0001-5967-0840; Selenev, Leonid/0000-0002-8121-9914 NR 69 TC 38 Z9 48 U1 1 U2 7 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0263-0346 EI 1469-803X J9 LASER PART BEAMS JI Laser Part. Beams PD DEC PY 2000 VL 18 IS 4 BP 661 EP 695 DI 10.1017/S0263034600184101 PG 35 WC Physics, Applied SC Physics GA 434ZK UT WOS:000168845600010 ER PT J AU DellaCorte, C AF DellaCorte, C TI December ... A time for reflection, remembering and looking ahead SO LUBRICATION ENGINEERING LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Washington, DC 20546 USA. RP DellaCorte, C (reprint author), NASA, Glenn Res Ctr, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD DEC PY 2000 VL 56 IS 12 BP 3 EP 3 PG 1 WC Engineering, Mechanical SC Engineering GA 381PU UT WOS:000165772700001 ER PT J AU Rozas, LP Minello, TJ Henry, CB AF Rozas, LP Minello, TJ Henry, CB TI An assessment of potential oil spill damage to salt marsh habitats and fishery resources in Galveston Bay, Texas SO MARINE POLLUTION BULLETIN LA English DT Article DE benthic infauna; estuary; fisheries; nekton; salt marsh; sediment hydrocarbon concentration ID CRUDE-OIL; AROMATIC-HYDROCARBONS; PENAEUS-AZTECUS; WEST-FALMOUTH; SEDIMENTS; IMPACT; WATER; POPULATIONS; SELECTION; PETROLEUM AB We sampled nekton, benthic infauna, and sediments in salt marshes of upper Galveston Bay, Texas to examine relationships between habitat use and sediment hydrocarbon concentration. Most marsh sediment samples were contaminated with relatively low concentrations of weathered petroleum hydrocarbons. We found few statistically significant negative relationships between animal density and hydrocarbon concentration (6 of 63 taxa examined using simple linear regression). Hydrocarbon concentration did not contribute significantly to Stepwise Multiple Regression models we used to explore potential relationships between animal densities and environmental parameters; in most cases where hydrocarbon concentration was an important variable in the models, the relationship was positive (i.e., animal densities increased with hydrocarbon concentration). Low hydrocarbon concentrations in sediments of upper Galveston Bay marshes could have contributed to our results either because levels were too low to be toxic or levels were toxic but too low to be detected by most organisms. Published by Elsevier Science Ltd. C1 Natl Marine Fisheries Serv, SE Fisheries Sci Ctr, Fishery Ecol Branch, Galveston Lab, Galveston, TX 77551 USA. NOAA Hazmat, Seattle, WA 98115 USA. RP Natl Marine Fisheries Serv, SE Fisheries Sci Ctr, Fishery Ecol Branch, Galveston Lab, 4700 Ave U, Galveston, TX 77551 USA. EM lawrence.rozas@noaa.gov NR 55 TC 13 Z9 13 U1 0 U2 21 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0025-326X EI 1879-3363 J9 MAR POLLUT BULL JI Mar. Pollut. Bull. PD DEC PY 2000 VL 40 IS 12 BP 1148 EP 1160 DI 10.1016/S0025-326X(00)00075-8 PG 13 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 384PU UT WOS:000165954700023 ER PT J AU Schoff, PK Ankley, GT AF Schoff, PK Ankley, GT TI Effects of methoprene and its derivatives on retinoid receptor activation and retinoid metabolism in transfected cell lines. SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 Natl Res Council, Duluth, MN 55804 USA. US EPA, Mid Continent Ecol Div, Duluth, MN USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC CELL BIOLOGY PI BETHESDA PA 8120 WOODMONT AVE, STE 750, BETHESDA, MD 20814-2755 USA SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD DEC PY 2000 VL 11 SU S MA 80 BP 16A EP 16A PG 1 WC Cell Biology SC Cell Biology GA 377QY UT WOS:000165525900081 ER PT J AU Hashemi, BB Pierson, DL McClure, JE AF Hashemi, BB Pierson, DL McClure, JE TI T-cell actin cytoskeleton: Adaptation and response in altered gravity conditions SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 Baylor Coll Med, Natl Space Biomed Res Inst, Houston, TX 77508 USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC CELL BIOLOGY PI BETHESDA PA 8120 WOODMONT AVE, STE 750, BETHESDA, MD 20814-2755 USA SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD DEC PY 2000 VL 11 SU S MA 361 BP 69A EP 69A PG 1 WC Cell Biology SC Cell Biology GA 377QY UT WOS:000165525900362 ER PT J AU Young, RB Bridge, KY AF Young, RB Bridge, KY TI Effect of beta-adrenergic agonists on cyclic AMP synthesis in chicken skeletal muscle cells in culture SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC CELL BIOLOGY PI BETHESDA PA 8120 WOODMONT AVE, STE 750, BETHESDA, MD 20814-2755 USA SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD DEC PY 2000 VL 11 SU S MA 540 BP 104A EP 104A PG 1 WC Cell Biology SC Cell Biology GA 377QY UT WOS:000165525900542 ER PT J AU Risin, D Risin, S Bick, RJ Sundaresan, A Pellis, NR AF Risin, D Risin, S Bick, RJ Sundaresan, A Pellis, NR TI Confocal microscopy analysis of PKC isoforms expression in peripheral blood mononuclear cells exposed to modeled microgravity. SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 Wyle Labs Life Sci, Biotechnol Program, Syst & Serv, Houston, TX 77058 USA. Univ Texas, Sch Med, Houston, TX USA. Wyle Labs Life Sci, Syst & Serv, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC CELL BIOLOGY PI BETHESDA PA 8120 WOODMONT AVE, STE 750, BETHESDA, MD 20814-2755 USA SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD DEC PY 2000 VL 11 SU S MA 1296 BP 249A EP 249A PG 1 WC Cell Biology SC Cell Biology GA 377QY UT WOS:000165525901300 ER PT J AU Searby, ND Steele, CR Globus, RK AF Searby, ND Steele, CR Globus, RK TI Hypergravity loading of cultured osteoblasts: Modeling and experimental analysis of cellular morphology and the cytoskeleton SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Stanford Mechan & Computat Div, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER SOC CELL BIOLOGY PI BETHESDA PA 8120 WOODMONT AVE, STE 750, BETHESDA, MD 20814-2755 USA SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD DEC PY 2000 VL 11 SU S MA 1832 BP 353A EP 353A PG 1 WC Cell Biology SC Cell Biology GA 377QY UT WOS:000165525901836 ER PT J AU Li, GH Sulkowski, GM Baer, LA Ronca, AE Wade, CE Sajdel-Sulkowska, EM AF Li, GH Sulkowski, GM Baer, LA Ronca, AE Wade, CE Sajdel-Sulkowska, EM TI Cerebellum development under altered gravity: expression of CD15 proteoglycans in the cerebellum of hypergravity-exposed rat neonates. SO MOLECULAR BIOLOGY OF THE CELL LA English DT Meeting Abstract C1 Harvard Univ, Brigham & Womens Hosp, Sch Med, Boston, MA 02115 USA. Harvard Univ, Sch Med, Boston, MA 02215 USA. NASA, Ames Res Ctr, Div Life Sci, Ames, IA 50011 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC CELL BIOLOGY PI BETHESDA PA 8120 WOODMONT AVE, STE 750, BETHESDA, MD 20814-2755 USA SN 1059-1524 J9 MOL BIOL CELL JI Mol. Biol. Cell PD DEC PY 2000 VL 11 SU S MA 2071 BP 399A EP 399A PG 1 WC Cell Biology SC Cell Biology GA 377QY UT WOS:000165525902075 ER PT J AU Srinivasan, R Brown, J Daw, MS Noebe, RD Mills, MJ AF Srinivasan, R Brown, J Daw, MS Noebe, RD Mills, MJ TI The mechanics of slip transition at intermediate temperatures in < 001 >-oriented NiAl single crystals I. Experimental observations of the decomposition of a < 111 > dislocations in Ni-44 at.% Al SO PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS AND MECHANICAL PROPERTIES LA English DT Article ID 1050 DEGREES K; PLASTIC-DEFORMATION; UNIFORM DEFORMATION; SYSTEMS; KINKING AB Ni-44 at.% Al single crystals were studied after compressive deformation along the hard orientation between 700 and 825 K. In order to understand the mechanism of the slip transition occurring at intermediate temperatures, compression was performed at various strain rates and to Various strain levels. Local decomposition of a[111] dislocations was observed between 750 and 800 K. At 800 K (the slip transition temperature), complete decomposition occurs into a[101] and a[010] dislocations. Several unique features are associated with this decomposition event, such as the preference for near-edge line directions (for the a[111] dislocations), significant strain softening between 800 and 900 K, and the effect of thermal activation in determining the extent of the actual decomposition event. C1 Ohio State Univ, Dept Mat Sci & Engn, Columbus, OH 43210 USA. Clemson Univ, Dept Phys & Astron, Clemson, SC 29634 USA. Motorola Inc, Computat Mat Grp, Austin, TX 78721 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Srinivasan, R (reprint author), Ohio State Univ, Dept Mat Sci & Engn, 116 W 19Th Ave, Columbus, OH 43210 USA. NR 23 TC 6 Z9 6 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0141-8610 J9 PHILOS MAG A JI Philos. Mag. A-Phys. Condens. Matter Struct. Defect Mech. Prop. PD DEC PY 2000 VL 80 IS 12 BP 2841 EP 2854 PG 14 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Physics, Applied; Physics, Condensed Matter SC Materials Science; Metallurgy & Metallurgical Engineering; Physics GA 386AA UT WOS:000166036300005 ER PT J AU Webb, EL Evangelista, MA Robinson, LA AF Webb, EL Evangelista, MA Robinson, LA TI Digital land-use classification using Space-Shuttle acquired orbital photographs: A quantitative comparison with Landsat TM imagery of a coastal environment, Chanthaburi, Thailand SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article AB The capability of Space-Shuttle-acquired orbital photography to provide accurate land-use classification using popular commercial software and accepted analytical procedures was investigated. The study area was the coastal region of the Chanthaburi Province, eastern Thailand, which exhibits a land-use pattern consisting of rice fields, shrimp farms, plantations/orchards, and patches of healthy and degraded mangrove e habitat. We used a typical image analysis protocol using ERDAS Imagine(TM) v8.2 combined with ground referencing, and compared the classification results using orbital photographs to results of the same study area using Landsat TM 5 imagery. The orbital photographs exhibited high spatial resolution, and performed similarly to Landsat for classification purposes. Accuracy assessments showed 81.3 percent accuracy of the ground referenced orbital photograph classification, and 83.3 percent for the Landsat image. Using a GIS overlay, we calculated 71 percent agreement between the two ground referenced image types. We conclude that, under the appropriate conditions, digitized orbital photographs can be an excellent source of spatial information for studies combining images of high spatial and spectral resolution. In addition to our results, we discuss the benefits and limitations to using orbital photographs for land-use classification. Orbital photographs can serve as a low-cost, complementary form of data to automated satellite images for assessments of basic habitat parameters. C1 Asian Inst Technol, Sch Environm REsources & Dev, Pathumthani 12120, Thailand. NASA, Lyndon B Johnson Space Ctr, Off Earth Sci, Houston, TX 77058 USA. RP Webb, EL (reprint author), Asian Inst Technol, Sch Environm REsources & Dev, POB 4 Klong Luang, Pathumthani 12120, Thailand. RI Webb, Edward/E-8343-2011; OI Webb, Edward/0000-0001-5554-9955; Robinson, Julie/0000-0002-6832-6459 NR 28 TC 8 Z9 8 U1 1 U2 2 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 USA SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD DEC PY 2000 VL 66 IS 12 BP 1439 EP 1449 PG 11 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 381LJ UT WOS:000165764100006 ER PT J AU Wu, MW Ning, CZ AF Wu, MW Ning, CZ TI Dyakonov-Perel effect on spin dephasing in n-type GaAs SO PHYSICA STATUS SOLIDI B-BASIC RESEARCH LA English DT Article ID EXCITONIC FARADAY-ROTATION; QUANTUM-WELLS; RELAXATION; SEMICONDUCTORS; PRECESSION; BEATS AB We study the: spin dephasing in n-doped bulk GaAs under moderate magnetic fields in Voigt configuration due to the Dvakonov-Perel (DP) effect by constructing and numerically solving the kinetic Bloch equations. Both acoustic (AC) and longitudinal optical (LO) phonon scattering, together with impurity scattering, are included in our theory, and their contributions to the spin dephasing time under the DP effect are examined in detail. The spin dephasing time is obtained from the time evolution of the incoherently summed spin coherence. We investigate how the spin dephasing time is affected hy temperature, impurity level, magnetic field, and electron density. In particular, our theory shows that spin dephasing time increases with increasing magnetic field. We find that, contrary to the prediction of previous simplified treatments of the DP effect, the spin dephasing time increases with temperature in the presence of impurity scattering. These results are in qualitative agreement with recent experiments. C1 Univ Calif Santa Barbara, Dept Chem, Santa Barbara, CA 93106 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Wu, MW (reprint author), Univ Calif Santa Barbara, Dept Chem, Santa Barbara, CA 93106 USA. RI Ning, C. Z./D-4699-2009 OI Ning, C. Z./0000-0003-4583-8889 NR 25 TC 41 Z9 41 U1 0 U2 4 PU WILEY-V C H VERLAG GMBH PI BERLIN PA PO BOX 10 11 61, D-69451 BERLIN, GERMANY SN 0370-1972 J9 PHYS STATUS SOLIDI B JI Phys. Status Solidi B-Basic Res. PD DEC PY 2000 VL 222 IS 2 BP 523 EP 534 DI 10.1002/1521-3951(200011)222:2<523::AID-PSSB523>3.3.CO;2-S PG 12 WC Physics, Condensed Matter SC Physics GA 393LY UT WOS:000166471100013 ER PT J AU Lee, H Rostovtsev, Y Scully, MO AF Lee, H Rostovtsev, Y Scully, MO TI Asymmetries between absorption and stimulated emission in driven three-level systems SO PHYSICAL REVIEW A LA English DT Article ID QUANTUM INTERFERENCE; POPULATION-INVERSION; RADIATION AMPLIFICATION; BROADENED RESONANCES; 3-LEVEL SYSTEM; LASER AB We present a physical picture explaining the asymmetries between absorption and stimulated emission occurring in the driven three-level systems. Based on a dressed-state picture, we obtain transition rates for absorption and stimulated emission separately, and show that the cancellation of absorption in the Lambda- and V-type systems are originated from different physical mechanisms. Furthermore, a simple analogy can be applied to cascade-type systems to show the absorption enhancement at two-photon resonance. C1 Texas A&M Univ, Dept Phys, College Stn, TX 77843 USA. Max Planck Inst Quantenopt, D-85748 Garching, Germany. RP Lee, H (reprint author), CALTECH, Jet Prop Lab, MS126-347, Pasadena, CA 91109 USA. NR 26 TC 9 Z9 9 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD DEC PY 2000 VL 62 IS 6 AR 063804 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 380JC UT WOS:000165697200099 ER PT J AU Stallcop, JR Partridge, H Levin, E AF Stallcop, JR Partridge, H Levin, E TI Effective potential energies and transport cross sections for interactions of hydrogen and nitrogen SO PHYSICAL REVIEW A LA English DT Article ID AB-INITIO CALCULATIONS; CORRELATED MOLECULAR CALCULATIONS; HARTREE-FOCK CALCULATIONS; 2ND VIRIAL-COEFFICIENTS; 11 POLYATOMIC GASES; GAUSSIAN-BASIS SETS; COLLISION INTEGRALS; BOND FUNCTIONS; ELECTRON CORRELATION; PERTURBATION-THEORY AB The interaction energies for N-2-He and N-2-H-2 are calculated by accurate ab initio methods. The virial coefficient and differential scattering cross section for N-2-H-2 are calculated; the theoretical results are compared with experimental data. The transport collision integrals for N-2-H-2 and N-2-N-2 interactions are calculated and tabulated; the results yield transport coefficients that compare well with measured data. Transport coefficients are found to be determined accurately from the interaction energies for a specific configuration of the molecule formed from the interaction partners. Comparisons with results of measurement and accurate calculations demonstrate that the transport properties of complex molecular interactions can be determined rapidly and fairly accurately from the interaction energies of simpler systems using combination rules for the short-range parameters of effective interaction energies and the coefficients for the long-range forces. The coefficients for a two-parameter temperature expansion of diffusion and viscosity are tabulated for a realistic universal potential-energy that is based primarily on the results of very accurate calculations of the He-He interaction energy. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Eloret Corp, Moffett Field, CA 94035 USA. RP Stallcop, JR (reprint author), NASA, Ames Res Ctr, MS 230-3, Moffett Field, CA 94035 USA. NR 72 TC 30 Z9 30 U1 0 U2 3 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD DEC PY 2000 VL 62 IS 6 AR 062709 DI 10.1103/PhysRevA.62.062709 PG 15 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 380JC UT WOS:000165697200052 ER PT J AU Gorham, PW Saltzberg, DP Schoessow, P Gai, W Power, JG Konecny, R Conde, ME AF Gorham, PW Saltzberg, DP Schoessow, P Gai, W Power, JG Konecny, R Conde, ME TI Radio-frequency measurements of coherent transition and Cherenkov radiation: Implications for high-energy neutrino detection SO PHYSICAL REVIEW E LA English DT Article ID FAR-INFRARED REGION; CERENKOV RADIATION; SYNCHROTRON RADIATION; ICE; SHOWERS; PULSES AB We report on measurements of (11-18)-cm wavelength radio emission from interactions of 15.2 MeV pulsed electron bunches at the Argonne Wakefield Accelerator. The electrons were observed both in a configuration where they produced primarily transition radiation from an aluminum foil, and in a configuration designed for the electrons to produce Cherenkov radiation in a silica sand target. Our aim was to emulate the large electron excess expected to develop during an electromagnetic cascade initiated by an ultrahigh-energy particle. Such charge asymmetries are predicted to produce strong coherent radio pulses, which are the basis for several experiments to detect high-energy neutrinos from the showers they induce in Antarctic ice and in the lunar regolith. We detected coherent emission which we attribute both to transition and possibly Cherenkov radiation at different levels depending on the experimental conditions. We discuss implications for experiments relying on radio emission for detection of electromagnetic cascades produced by ultrahigh-energy neutrinos. C1 Argonne Natl Lab, Argonne, IL 60493 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gorham, PW (reprint author), Argonne Natl Lab, 9700 S Cass Ave, Argonne, IL 60493 USA. NR 34 TC 66 Z9 67 U1 0 U2 2 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 DEC PY 2000 VL 62 IS 6 BP 8590 EP 8605 DI 10.1103/PhysRevE.62.8590 PN B PG 16 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA 383JN UT WOS:000165879500045 ER PT J AU Kassemi, M Rashidnia, N AF Kassemi, M Rashidnia, N TI Steady and oscillatory thermocapillary convection generated by a bubble SO PHYSICS OF FLUIDS LA English DT Article ID MARANGONI NUMBER CONVECTION; TENSION DRIVEN FLOW; LOW-PRANDTL-NUMBER; LIQUID BRIDGES; SQUARE CAVITY; HEATED WALL; BUOYANCY; INSTABILITIES; TEMPERATURE; FLUID AB In this article, we study steady and oscillatory thermocapillary and natural convective flows generated by a bubble on a heated solid surface. The dynamic characteristics of the time-dependent convection are captured using a combined numerical-experimental approach. The index of refraction fringe distribution patterns constructed numerically by taking an inverse Abel transform of the computed temperature fields are compared directly to the experimental Wollaston prism (WP) interferograms for both steady-state and oscillatory convection. The agreement between numerical predictions and experimental measurements is excellent in all cases. It is shown that below the critical Marangoni number, steady-state conditions are attainable. With increasing Ma, there is a complete transition from steady state up to a final nonperiodic fluctuating flow regime through several complicated symmetric and asymmetric oscillatory states. The most prevalent oscillatory mode corresponds to a symmetric up and down fluctuation of the temperature and flow fields associated with an axially traveling wave. Careful examination of the numerical results reveals that the origin of this class of convective instability is closely related to an intricate temporal coupling between large-scale thermal structures which develop in the fluid in the form of the cold return flow and the temperature sensitive surface of the bubble. Gravity and natural convection play an important role in the formation of these thermal structures and the initiation of the oscillatory convection. Consequently, at low-g, the time evolution of the temperature and flow fields around the bubble are very different from their 1-g counterparts for all Marangoni numbers. (C) 2000 American Institute of Physics. [S1070-6631(00)01012-6]. C1 NASA, Natl Ctr Micrograv Res, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Kassemi, M (reprint author), NASA, Natl Ctr Micrograv Res, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 33 TC 24 Z9 24 U1 0 U2 5 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD DEC PY 2000 VL 12 IS 12 BP 3133 EP 3146 AR PII [S1070-6631(00)01012-6] DI 10.1063/1.1321263 PG 14 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 369TV UT WOS:000165083800005 ER PT J AU Badhwar, GD Huff, H Wilkins, R AF Badhwar, GD Huff, H Wilkins, R TI Alterations in dose and lineal energy spectra under different shieldings in the Los Alamos high-energy neutron field SO RADIATION RESEARCH LA English DT Article ID RESPONSE FUNCTION AB Nuclear interactions of space radiation with shielding materials result in alterations in dose and lineal energy spectra that depend on the specific elemental composition, density and thickness of the material. The shielding characteristics of materials have been studied using charged-particle beams and radiation transport models by examining the risk reduction using the conventional dose-equivalent approach, Secondary neutrons contribute a significant fraction of the total radiation exposure in space. An experiment to study the changes in dose and lineal energy spectra by shielding materials was carried out at the Los Alamos Nuclear Science Center neutron facility. In the energy range of about 2 to 200 MeV, this neutron spectrum is similar in shape within a factor of about 2 to the spectrum expected in the International Space Station habitable modules. It is shown that with a shielding thickness of about 5 g cm(-2), the conventional radiation risk increases, in some cases by as much as a factor of 2, but decreases with thicknesses of about of 20 g cm(-2). This suggests that care must be taken in evaluating the shielding effectiveness of a given material by including both the charged-particle and neutron components of space radiation, (C) 2000 by Radiation Research Society. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Prairie View A&M Univ, Prairie View, TX 77446 USA. RP Badhwar, GD (reprint author), NASA, Lyndon B Johnson Space Ctr, 2101 NASA Rd 1,Code SN3, Houston, TX 77058 USA. NR 19 TC 12 Z9 12 U1 1 U2 2 PU RADIATION RESEARCH SOC PI OAK BROOK PA 2021 SPRING RD, STE 600, OAK BROOK, IL 60521 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD DEC PY 2000 VL 154 IS 6 BP 697 EP 704 DI 10.1667/0033-7587(2000)154[0697:AIDALE]2.0.CO;2 PG 8 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 380MG UT WOS:000165705200012 PM 11096428 ER PT J AU Yasuda, H Badhwar, GD Komiyama, T Fujitaka, K AF Yasuda, H Badhwar, GD Komiyama, T Fujitaka, K TI Effective dose equivalent on the ninth Shuttle-Mir Mission (STS-91) SO RADIATION RESEARCH LA English DT Article ID GALACTIC COSMIC-RAYS; THERMOLUMINESCENT DETECTORS; RADIATION; SPACE; PARTICLES; EFFICIENCY; DOSIMETRY; CR-39; TLDS; LIF AB Organ and tissue doses and effective dose equivalent were measured using a life-size human phantom on the ninth Shuttle-Mir Mission (STS-91, June 1998), a 9.8-day spaceflight at low-Earth orbit (about 400 km in altitude and 51.65 degrees in inclination), The doses were measured at 59 positions using a combination of thermoluminescent dosimeters of Mg2SiO4:Tb (TDMS) and plastic nuclear track detectors (PNTD), In correcting the change in efficiency of the TDMS, it was assumed that reduction of efficiency is attributed predominantly to HZE particles with energy greater than 100 MeV nucleon(-1), A conservative calibration curve was chosen for determining LET from the PNTD track-formation sensitivities. The organ and tissue absorbed doses during the mission ranged from 1.7 to 2.7 mGy and varied by a factor of 1.6. The dose equivalent ranged from 3.4 to 5.2 mSv and varied by a factor of 1.5 on the basis of the dependence of Q on LET in the 1990 recommendations of the ICRP, The effective quality factor (Q(e)) varied from 1.7 to 2.4. The dose equivalents for several radiation-sensitive organs, such as the stomach, lung, gonad and breast, were not significantly different from the skin dose equivalent (H-skin). The effective dose equivalent was evaluated as 4.1 mSv, which was about 90% of the H-skin. (C) 2000 by Radiation Research Society. C1 Natl Inst Radiol Sci, Int Space Radiat Lab, Inage Ku, Chiba 2638555, Japan. Natl Space Dev Agcy Japan, Tsukuba, Ibaraki 3058505, Japan. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Yasuda, H (reprint author), Natl Inst Radiol Sci, Int Space Radiat Lab, Inage Ku, 4-9-1 Anagawa, Chiba 2638555, Japan. NR 45 TC 40 Z9 41 U1 0 U2 2 PU RADIATION RESEARCH SOC PI OAK BROOK PA 2021 SPRING RD, STE 600, OAK BROOK, IL 60521 USA SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD DEC PY 2000 VL 154 IS 6 BP 705 EP 713 DI 10.1667/0033-7587(2000)154[0705:EDEOTN]2.0.CO;2 PG 9 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA 380MG UT WOS:000165705200013 PM 11096429 ER PT J AU Kenward, T Lettenmaier, DP Wood, EF Fielding, E AF Kenward, T Lettenmaier, DP Wood, EF Fielding, E TI Effects of digital elevation model accuracy on hydrologic predictions SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID TERRAIN AB The effect of vertical accuracy of digital elevation models (DEMs) on hydrologic prediction accuracy was evaluated by comparing three DEMs and associated stream-flow simulations for the 7.2 km(2) USDA-ARS watershed at Mahantango Creek, PA. The DEMs were the standard 30 m USG 7.5' DEM, a 5 m product derived from low altitude aerial photography, and a 30 m product derived from interferometric processing of Spaceborne Imaging Radar-C (SIR-C). Statistical analysis of the DEMs showed that the USGS DEM had the typical stipling errors resulting from processing of the source digital contour maps, and a vertical error structure related to the topographic attributes of the watershed. The SIR-C DEM had a vertical offset of about 50 m from the high resolution and USGS DEMs, as well as error features that were somewhat related to topographic features. Inaccuracies in both the USGS and SIR-C DEMs were apparent in the drainage network, as well as in spatial images of elevation, slope, and contributing area. Comparisons of runoff predicted using a hydrologic model based on the three DEMs showed that mean annual predicted runoff volumes were 0.3% and 7.0% larger for the USGS and SIR-C DEMs, respectively, as compared to the reference DEM. Much larger differences were apparent in individual hydrographs; and the USGS and SIR-C DEMs predicted lower peaks, and higher base flows, than did the reference. (C) Elsevier Science Inc., 2000. C1 Univ Washington, Dept Civil Engn, Seattle, WA 98195 USA. Princeton Univ, Dept Civil & Environm Engn & Operat Res, Princeton, NJ 08544 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Lettenmaier, DP (reprint author), Univ Washington, Dept Civil & Environm Engn, Box 352700, Seattle, WA 98195 USA. RI lettenmaier, dennis/F-8780-2011; Fielding, Eric/A-1288-2007; OI lettenmaier, dennis/0000-0003-3317-1327; Fielding, Eric/0000-0002-6648-8067; Wood, Eric/0000-0001-7037-9675 NR 20 TC 61 Z9 63 U1 1 U2 12 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD DEC PY 2000 VL 74 IS 3 BP 432 EP 444 DI 10.1016/S0034-4257(00)00136-X PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 387UL UT WOS:000166140200010 ER PT J AU Gao, BC Li, RR AF Gao, BC Li, RR TI Quantitative improvement in the estimates of NDVI values from remotely sensed data by correcting thin cirrus scattering effects SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID MODIS; CLOUD; CHANNEL AB The Normalized Difference Vegetation Index (NDVI) has been used extensively for remote sensing of vegetation for many years. This index uses radiances or reflectances from a red channel at 0.66 mum and near-infrared channel at 0.86 mum. Thin cirrus clouds frequently contaminate remotely sensed data acquired from aircraft and satellite platforms. They introduce additional scattered radiances to the 0.66-mum and 0.86-mum channels. To obtain unbiased estimates of NDVI values from remotely sensed data, the cirrus scattering effects must be removed. We recently have developed an empirical technique for removing thin cirrus scattering effects using the sensitive 1.375-mum cirrus-detecting channel. In this article, we demonstrate that the estimates of NDVI values van be improved quantitatively after the removal of thin cirrus effects. Pairs of spectral imaging data, with and nearly without thin cirrus contamination, acquired with the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) are used in this study. Because a special channel centered at 1.375 mum has been implemented on the Moderate Resolution Imaging Spectrometer (MODIS) for detecting thin cirrus clouds from space, it is possible to remove thin cirrus scattering effects from MODIS channels below 1 mum and to yield improved global estimates of NDVI values from MODIS data. (C) 2000 Published by Elsevier Science Ireland Ltd. C1 USN, Remote Sensing Div, Res Lab, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. RP Gao, BC (reprint author), USN, Remote Sensing Div, Res Lab, Code 7212 NRL ,4555 Overlook Ave SW, Washington, DC 20375 USA. NR 11 TC 10 Z9 14 U1 1 U2 3 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD DEC PY 2000 VL 74 IS 3 BP 494 EP 502 DI 10.1016/S0034-4257(00)00141-3 PG 9 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 387UL UT WOS:000166140200015 ER PT J AU Keenan, FP Pinfield, DJ Mathioudakis, M Aggarwal, KM Thomas, RJ Brosius, JW AF Keenan, FP Pinfield, DJ Mathioudakis, M Aggarwal, KM Thomas, RJ Brosius, JW TI S XI emission lines in active region spectra obtained with the Solar EUV Rocket Telescope and Spectrograph (SERTS) SO SOLAR PHYSICS LA English DT Article ID EXTREME-ULTRAVIOLET-SPECTRA; TRANSITIONS; WAVELENGTHS; DIAGNOSTICS; STRENGTHS; RATIOS; IONS; SUN AB Theoretical electron density sensitive emission line ratios involving a total of eleven 2s(2)2p(2)-2s2p(3) transitions in S XI between 187 and 292 Angstrom are presented. A comparison of these with solar active region observations obtained during rocket flights by the Solar EUV Rocket Telescope and Spectrograph (SERTS) reveals generally good agreement between theory and experiment. However, the 186.87 Angstrom line is masked by fairly strong Fe XII emission at the same wavelength, while 239.83 Angstrom is blended with an unknown feature, and 285.58 Angstrom is blended with possibly N IV 285.56 Angstrom. In addition, the 191.23 Angstrom line appears to be more seriously blended with an Fe XIII feature than previously believed. The presence of several new S XI lines is confirmed in the SERTS spectra, at wavelengths of 188.66, 247.14 and 291.59 Angstrom, in excellent agreement with laboratory measurements. In particular, the detection of the 2s(2)2p(2) P-3(1) -2s2p(3) P-3(0,1) transitions at 242.91 Angstrom is the first time (to our knowledge) that this feature has been identified in the solar spectrum. The potential usefulness of the S XI line ratios as electron density diagnostics for the solar transition region and corona is briefly discussed. 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 USA. Raytheon ITSS, Lanham, MD 20706 USA. RP Keenan, FP (reprint author), Queens Univ Belfast, Dept Pure & Appl Phys, Belfast BT7 1NN, Antrim, North Ireland. NR 27 TC 7 Z9 7 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 DEC PY 2000 VL 197 IS 2 BP 253 EP 262 DI 10.1023/A:1026572802550 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 396NY UT WOS:000166644500004 ER PT J AU Kaufmann, P Trottet, G de Castro, CGG Costa, JER Raulin, JP Schwartz, RA Magun, A AF Kaufmann, P Trottet, G de Castro, CGG Costa, JER Raulin, JP Schwartz, RA Magun, A TI Correlated east time structures at millimeter waves and hard X-rays during a solar burst SO SOLAR PHYSICS LA English DT Article ID TRAP-PRECIPITATING ELECTRONS; GAMMA-RAY; 48 GHZ; FLARES; EMISSION; DECONVOLUTION; ACCELERATION; SENSITIVITY; RESOLUTION; RADIATION AB We present an analysis of the time profiles detected during a solar impulsive flare, observed at one-millimeter radio frequency (48 GHz) and in three hard X-ray energy bands (25-62, 62-111, and 111-325 keV) with high sensitivity and time resolution. The time profiles of all emissions exhibit fast time structures of 200-300 ms half power duration which appear in excess of a slower component varying on a typical time scale of 10 s. The amplitudes of both the slow and fast variations observed at 48 GHz are not proportional to those measured in the three hard X-ray energy bands. However, the fast time structures detected in both domains are well correlated and occur simultaneously within 64 ms, the time resolution of the hard X-ray data. In the context of a time-of-flight flare model, our results put strong constraints on the acceleration time scales of electrons to MeV energies. C1 CRAAE, Inst Presbiteriano Mackenzie, BR-01302907 Sao Paulo, Brazil. Observ Paris, Sect Meudon, DASOP, CNRS,UMR 8645, F-92195 Meudon, France. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Raytheon ITSS, Greenbelt, MD 20771 USA. Univ Bern, Inst Appl Phys, CH-3012 Bern, Switzerland. RP Kaufmann, P (reprint author), CRAAE, Inst Presbiteriano Mackenzie, Rua Consolacao 896, BR-01302907 Sao Paulo, Brazil. RI Costa, Joaquim/G-3840-2012; Gimenez de Castro, Carlos Guillermo/I-4367-2016; OI Gimenez de Castro, Carlos Guillermo/0000-0002-8979-3582; Costa, Joaquim/0000-0002-0703-4735 NR 51 TC 11 Z9 11 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 DEC PY 2000 VL 197 IS 2 BP 361 EP 374 DI 10.1023/A:1026504704381 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 396NY UT WOS:000166644500009 ER PT J AU Cooper, BA Eckel, A Butcher, T Nelson, D AF Cooper, BA Eckel, A Butcher, T Nelson, D TI New Acoustical Testing Laboratory at NASA SO SOUND AND VIBRATION LA English DT Editorial Material C1 NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. Eckel Ind Inc, Cambridge, MA USA. Natl Instruments, Austin, TX USA. Nelson Acoust Engn Inc, Elgin, TX USA. RP Cooper, BA (reprint author), NASA, John H Glenn Res Ctr, Cleveland, OH 44135 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU ACOUSTICAL PUBL INC PI BAY VILLAGE PA 27101 E OVIATT RD PO BOX 40416, BAY VILLAGE, OH 44140 USA SN 0038-1810 J9 SOUND VIB JI Sound Vib. PD DEC PY 2000 VL 34 IS 12 BP 10 EP + PG 5 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 392GX UT WOS:000166404300003 ER PT J AU Szego, K Glassmeier, KH Bingham, R Bogdanov, A Fischer, C Haerendel, G Brinca, A Cravens, T Dubinin, E Sauer, K Fisk, L Gombosi, T Schwadron, N Isenberg, P Lee, M Mazelle, C Mobius, E Motschmann, U Shapiro, VD Tsurutani, B Zank, G AF Szego, K Glassmeier, KH Bingham, R Bogdanov, A Fischer, C Haerendel, G Brinca, A Cravens, T Dubinin, E Sauer, K Fisk, L Gombosi, T Schwadron, N Isenberg, P Lee, M Mazelle, C Mobius, E Motschmann, U Shapiro, VD Tsurutani, B Zank, G TI Physics of mass loaded plasmas SO SPACE SCIENCE REVIEWS LA English DT Review ID SOLAR-WIND INTERACTION; AMPTE ARTIFICIAL COMET; P-GRIGG-SKJELLERUP; PICK-UP IONS; FREQUENCY ELECTROMAGNETIC-WAVES; MAGNETIC-FIELD OBSERVATIONS; PRESSURE-BALANCED STRUCTURES; ELECTRON-IMPACT IONIZATION; VELOCITY SPACE DIFFUSION; HALLEY BOW SHOCK AB In space plasmas the phenomenon of mass loading is common. Comets are one of the most evident objects where mass loading controls to a large extent the structure and dynamics of its plasma environment. New charged material is implanted to the fast streaming solar wind by planets, moons, other solar system objects, and even by the interstellar neutral gas flowing through our solar system. In this review we summarize both the current observations and the relevant theoretical approaches. First we survey the MHD methods, starting with a discussion how mass loading affects subsonic and supersonic gasdynamics flows, continuing this with single and multi-fluid MHD approaches to describe the flow when mass, momentum and energy is added, and we finish this section by the description of mass loaded shocks. Next we consider the kinetic approach to the same problem, discussing wave excitations, pitch angle and energy scattering in linear and quasi-linear approximations. The different descriptions differ in assumptions and conclusions; we point out the differences, but it is beyond the scope of the paper to resolve all the conflicts. Applications of these techniques to comets, planets, artificial ion releases, and to the interplanetary neutrals are reviewed in the last section, where observations are also compared with models, including hybrid simulations as well. We conclude the paper with a summary of the most important open, yet unsolved questions. C1 KFKI Res Inst Particle & Nucl Phys, H-1525 Budapest, Hungary. Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Meteorol, D-38106 Braunschweig, Germany. Rutherford Appleton Lab, Oxford OX1 5RN, England. Max Planck Inst Extraterr Phys, D-85740 Garching, Germany. Inst Super Tecn, Ctr Fis Plasmas, P-1096 Lisbon, Portugal. Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA. Max Planck Inst Aeron, D-37189 Katlenburg Lindau, Germany. Univ Michigan, Ann Arbor, MI 48109 USA. Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA. CNRS, CESR, F-31028 Toulouse 4, France. Tech Univ Carolo Wilhelmina Braunschweig, Inst Theoret Phys, D-38106 Braunschweig, Germany. Univ Calif San Diego, Dept Phys, La Jolla, CA 92093 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. RP Szego, K (reprint author), KFKI Res Inst Particle & Nucl Phys, POB 49, H-1525 Budapest, Hungary. RI Gombosi, Tamas/G-4238-2011; OI Gombosi, Tamas/0000-0001-9360-4951; Moebius, Eberhard/0000-0002-2745-6978 NR 418 TC 60 Z9 60 U1 1 U2 12 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD DEC PY 2000 VL 94 IS 3-4 BP 429 EP 671 DI 10.1023/A:1026568530975 PG 243 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 379FP UT WOS:000165631600001 ER PT J AU Zhang, J Ge, LX Kouatchou, J AF Zhang, J Ge, LX Kouatchou, J TI A two colorable fourth-order compact difference scheme and parallel iterative solution of the 3D convection diffusion equation SO MATHEMATICS AND COMPUTERS IN SIMULATION LA English DT Article DE 3D convection diffusion equation; fourth-order compact difference schemes; multigrid method; parallel computation ID MULTIGRID SOLVER AB A new fourth-order compact difference scheme for the three-dimensional (3D) convection diffusion equation with variable coefficients is presented. The novelty of this new difference scheme is that it only requires 15 grid points and that it can be decoupled with two colors. The entire computational grid can be updated in two parallel subsweeps with a Gauss-Seidel type iterative method. This is compared with the known 19-point fourth-order compact difference scheme which requires four colors to decouple the computational grid. Numerical results, with multigrid methods implemented on a shared memory parallel computer, are presented to compare the 15-and 19-point fourth-order compact schemes. (C) 2000 IMACS. Published by Elsevier Science B.V. All rights reserved. C1 Univ Kentucky, Dept Comp Sci, Lexington, KY 40506 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Zhang, J (reprint author), Univ Kentucky, Dept Comp Sci, 773 Anderson Hall, Lexington, KY 40506 USA. RI Koutachou, Jules/D-4773-2016 OI Koutachou, Jules/0000-0002-5525-9875 NR 40 TC 20 Z9 22 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-4754 J9 MATH COMPUT SIMULAT JI Math. Comput. Simul. PD NOV 30 PY 2000 VL 54 IS 1-3 BP 65 EP 80 DI 10.1016/S0378-4754(00)00205-6 PG 16 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA 382FU UT WOS:000165813000004 ER PT J AU Stern, D Eisenhardt, P Spinrad, H Dawson, S van Breugel, W Dey, A de Vries, W Stanford, SA AF Stern, D Eisenhardt, P Spinrad, H Dawson, S van Breugel, W Dey, A de Vries, W Stanford, SA TI Evidence against a redshift z > 6 for the galaxy STIS123627+621755 SO NATURE LA English DT Article ID LUMINOSITY DENSITY; WHITE-DWARF; FIELD; UNIVERSE AB The identification of galaxies at extreme distances provides the most direct information about the earliest phases of galaxy formation. But at redshifts z>5 even the most luminous galaxies appear faint; the interpretation of low signal-to-noise ratio data is difficult and misidentifications do occur. Here we report optical and near-infrared observations of the source STIS123627+621755, which was previously suggested to be at a redshift of 6.68 (ref. 1). At that redshift, and with the reported 1 spectral energy distribution, the galaxy should be essentially invisible at wavelengths less than 9,300 Angstrom, because the intervening intergalactic medium absorbs almost all light energetic enough to ionize neutral hydrogen-that is, with wavelengths less than the redshifted Lyman limit of lambda = (1 + z) x 912 Angstrom. At near-infrared wavelengths, however, the galaxy should be relatively bright. Here we report a detection of the galaxy at 6,700 Angstrom and a non-detection at a wavelength of 1.2 mum, contrary to expectations for z approximate to 6.68. The data conservatively require that STIS123627+621755 has a redshift z< 6. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Lawrence Livermore Natl Lab, Inst Geophys & Planetary Phys, Livermore, CA 94550 USA. Kitt Peak Natl Observ, Natl Opt Astron Observ, Tucson, AZ 85726 USA. Univ Calif Davis, Dept Phys, Davis, CA 95616 USA. RP Dawson, S (reprint author), CALTECH, Jet Prop Lab, Mail Stop 169-327, Pasadena, CA 91109 USA. EM stern@zwolfkinder.jpl.nasa.gov OI Stern, David/0000-0002-1847-6483 NR 18 TC 13 Z9 13 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 NOV 30 PY 2000 VL 408 IS 6812 BP 560 EP 562 DI 10.1038/35046027 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 377WE UT WOS:000165548600110 PM 11117737 ER PT J AU Hunton, DE Ballenthin, JO Borghetti, JF Federico, GS Miller, TM Thorn, WF Viggiano, AA Anderson, BE Cofer, WR McDougal, DS Wey, CC AF Hunton, DE Ballenthin, JO Borghetti, JF Federico, GS Miller, TM Thorn, WF Viggiano, AA Anderson, BE Cofer, WR McDougal, DS Wey, CC TI Chemical ionization mass spectrometric measurements of SO2 emissions from jet engines in flight and test chamber operations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AIRCRAFT EXHAUST PLUMES; ULTRAFINE AEROSOL-PARTICLES; DIFFERENT SULFUR CONTENTS; AIRBORNE OBSERVATIONS; SITU OBSERVATIONS; CONTRAIL FORMATION; CRUISE ALTITUDE; FLOW REACTOR; AIR; ION AB We report the results of two measurements of the concentrations and emission indices of gas-phase sulfur dioxide (EI(SO2)) in the exhaust of an F100-200E turbofan engine. The broad goals of both experiments were to obtain exhaust sulfur speciation and aerosol properties as a function of fuel sulfur content. In the first campaign, an instrumented NASA T-39 Sabreliner aircraft flew in close formation behind several F-16 fighter aircraft to obtain near-field plume composition and aerosol properties. In the second, an F-100 engine of the same type was installed in an altitude test chamber at NASA Glenn Research Center where gas composition and nonvolatile aerosol concentrations and size distributions were obtained at the exit plane of the engine. In both experiments, SO2 concentrations were measured with the Air Force Research Laboratory chemical ionization mass spectrometer as a function of altitude, engine power, and fuel sulfur content. A significant aspect of the program was the use of the same fuels, the same engine type, and many of the same diagnostics in both campaigns. Several different fuels were purchased specifically fur these experiments, including high-sulfur Jet A (similar to 1150 ppmm S), low-sulfur Jet A (similar to 10 ppmm S), medium-sulfur mixtures of these two fuels, and military JP-8 + 100 (similar to 170 and similar to 300 ppmm S). The agreement between the flight and test cell measurements of SO2 concentrations was excellent, showing an overall precision of better than +/-10% and an estimated absolute accuracy of +/-20%. The EI(SO2) varied from 2.49 g SO2/kg fuel for the high-sulfur fuel in the lest chamber to less than 0.01 g/kg for the lowest-sulfur fuel. No dependence of emission index on engine power, altitude or simulated altitude, separation distance or plume age, or the presence of contrails was observed. In all experiments the measured EI(SO2) was consistent with essentially all of the fuel sulfur appearing as gas-phase SO2 in the exhaust. However, accurate determination of S(IV) to S(VI) conversion was hampered by inconsistencies in the assays of total fuel sulfur content. C1 USAF, Res Lab, VSBP, Space Vehicles Directorate, Hanscom AFB, MA 01731 USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. NASA, John H Glenn Res Ctr, High Speed Syst Off, Engine Components Div, Cleveland, OH 44135 USA. RP Hunton, DE (reprint author), USAF, Res Lab, VSBP, Space Vehicles Directorate, 29 Randolph Rd, Hanscom AFB, MA 01731 USA. EM donald.hunton@hanscom.af.mil NR 66 TC 22 Z9 22 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 NOV 27 PY 2000 VL 105 IS D22 BP 26841 EP 26855 DI 10.1029/2000JD900383 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 378MY UT WOS:000165589200004 ER PT J AU Tarasova, TA Nobre, CA Eck, TF Holben, BN AF Tarasova, TA Nobre, CA Eck, TF Holben, BN TI Modeling of gaseous, aerosol, and cloudiness effects on surface solar irradiance measured in Brazil's Amazonia 1992-1995 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DELTA-EDDINGTON APPROXIMATION; RADIATION AB The effects of water vapor, aerosol, and cloudiness on the incident surface solar irradiance continuously measured in Brazil's Amazonia at six observational sites from 1992 to 1995 are examined by means of a clear-sky broadband radiative transfer model. The aerosol optical depth and precipitable water, both retrieved from Sun photometer measurements, serve as inputs to the model. Computed monthly mean values of clear-sky surface irradiance are analyzed in conjunction with the monthly mean values of all-sky surface irradiance measured on the ground. To assess the effect of cloudiness, we present the cloud radiative forcing and cloud radiative forcing ratio at the surface, both widely employed in cloud radiation budget studies, By its definition the monthly mean cloud radiative forcing (cloud radiative forcing; ratio) is the difference (ratio) between surface solar irradiances under all-sky an clear-sky conditions. The analysis of the irradiances, as computed and as measured, shows that during the wet season the gaseous and cloudiness effects on the! solar radiation attenuation in the atmosphere are comparable, while the aerosol influence is much smaller. The aerosol effect increases and cloudiness effect decreases in the second half of the dry season. Thus during the biomass burning period ill southern Amazonia, the water vapor and aerosol effects become comparable, while the cloudiness impact is 2-3 times smaller. Both cloudiness and aerosol effects have strong seasonal variations, while the gaseous effect changes slightly throughout the year. C1 Inst Nacl Pesquisas Espaciais, Ctr Previsao Tempo & Estudos Climat, BR-12630000 Cachoeira Paulista, SP, Brazil. NASA, Goddard Space Flight Ctr, Raytheon ITSS Corp, Greenbelt, MD 20771 USA. RP Tarasova, TA (reprint author), Inst Nacl Pesquisas Espaciais, Ctr Previsao Tempo & Estudos Climat, Rodovia Presidente Dutra,Km 40, BR-12630000 Cachoeira Paulista, SP, Brazil. EM tatiana@cptec.inpe.br; nobre@cptec.inpe.br; tom@spamer.gsfc.nasa.gov; brent@spamer.gsfc.nasa.gov RI ECK, THOMAS/D-7407-2012 NR 22 TC 8 Z9 8 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 NOV 27 PY 2000 VL 105 IS D22 BP 26961 EP 26969 DI 10.1029/2000JD900433 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 378MY UT WOS:000165589200012 ER PT J AU Tegen, I Koch, D Lacis, AA Sato, M AF Tegen, I Koch, D Lacis, AA Sato, M TI Trends in tropospheric aerosol loads and corresponding impact on direct radiative forcing between 1950 and 1990: A model study SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EXTINCTION OPTICAL-THICKNESS; GENERAL-CIRCULATION MODEL; ALPINE ICE CORE; ANTHROPOGENIC SULFATE; MINERAL DUST; BLACK CARBON; AMMONIUM-SULFATE; LIGHT-ABSORPTION; UNITED-STATES; SOOT AEROSOL AB Global aerosol optical thicknesses and radiative properties need to be known for the study of decadal temperature change. Aerosol distributions have been developed from global transport models for a mixture of sulfate and carbonaceous aerosols from fossil fuel burning, including also contributions from other major aerosol types such as soil dust and sea salt. Between the years 1950 and 1990 the aerosol distributions change due to changes in emissions of SO2 and carbon particles from fossil fuel burning. The optical thickness of fossil fuel derived aerosols increased by nearly a factor of 3 during this period, with particularly strong increase in eastern Asia. In countries where environmental laws came into effect since the early 1980s (e.g., United States and western Europe), emissions and consequently aerosol optical thicknesses did not increase considerably after 1980, resulting in a sl lift in the global distribution pattern. In addition to the optical thickness, aerosol single scattering albedos may have changed during this period due to different trends in absorbing black carbon and reflecting sulfate aerosols. However, due to uncertainties in the emission trends, which are especially large in the case of carbonaceous aerosols, such change cannot be determined with any confidence. Radiative forcing of this aerosol distribution is calculated for several scenarios. Uncertainties in the contribution of the strongly absorbing black carbon aerosol leads to a range in top-of-atmosphere forcings of approximate to -0.5 to +0.1 Wm(-2). C1 Max Planck Inst Biogeochem, D-07701 Jena, Germany. Columbia Univ, Ctr Climate Syst Res, New York, NY 10025 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Tegen, I (reprint author), Max Planck Inst Biogeochem, POB 100164, D-07701 Jena, Germany. EM itegen@bgc-jena.mpg.de RI Lacis, Andrew/D-4658-2012 NR 55 TC 77 Z9 80 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 27 PY 2000 VL 105 IS D22 BP 26971 EP 26989 DI 10.1029/2000JD900280 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 378MY UT WOS:000165589200013 ER PT J AU Barlow, NG Boyce, JM Costard, FM Craddock, RA Garvin, JB Sakimoto, SEH Kuzmin, RO Roddy, DJ Soderblom, LA AF Barlow, NG Boyce, JM Costard, FM Craddock, RA Garvin, JB Sakimoto, SEH Kuzmin, RO Roddy, DJ Soderblom, LA TI Standardizing the nomenclature of Martian impact crater ejecta morphologies SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID WIND EROSION; MARS; DEPOSITS; DEGRADATION; VOLATILES; HIGHLANDS; LATITUDE; REGIONS; BASIN; WATER AB The Mars Crater Morphology Consortium recommends the use of a standardized nomenclature system when discussing Martian impact crater ejecta morphologies. The system utilizes nongenetic descriptors to identify the various ejecta morphologies seen on Mars. This system is designed to facilitate communication and collaboration between researchers. Crater morphology databases will be archived through the U.S. Geological Survey in Flagstaff, where a comprehensive catalog of Martian crater morphologic information will be maintained. C1 Univ Cent Florida, Dept Phys, Orlando, FL 32816 USA. NASA, Headquarters, Off Space Sci, Washington, DC 20546 USA. CNRS, Lab Geol Dynam Terre & Planetes, UMR 8616, F-91405 Orsay, France. Smithsonian Inst, Natl Air & Space Museum, Ctr Earth & Planetary Studies, Washington, DC 20560 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Russian Acad Sci, Vernadsky Inst, Moscow 117975, Russia. US Geol Survey, Flagstaff, AZ 86001 USA. RP Barlow, NG (reprint author), Univ Cent Florida, Dept Phys, MAP 310, Orlando, FL 32816 USA. RI Craddock, Robert/B-3884-2013 NR 42 TC 107 Z9 107 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD NOV 25 PY 2000 VL 105 IS E11 BP 26733 EP 26738 DI 10.1029/2000JE001258 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 376AL UT WOS:000165435600003 ER PT J AU Rubincam, DP AF Rubincam, DP TI Pluto and Charon: A case of precession-orbit resonance? SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CLIMATE; MARS; OBLIQUITY; TILT AB Pluto may be the only known case of precession-orbit resonance in the solar system. The Pluto-Charon system orbits the Sun with a period of 1 Plutonian year, which is 250.8 Earth years. The observed parameters of the system are such that Charon may cause Pluto to precess with a period near 250.8 Earth years. This gives rise to two possible resonances, heretofore unrecognized. The first is due to Pluto's orbit being highly eccentric, giving solar torques on Charon with a period of 1 Plutonian year. Charon, in turn, drives Pluto near its precession period. Volatiles, which are expected to shuttle across Pluto's surface between equator and pole as the insolation varies, might change the planet's dynamical flattening enough so that Pluto crosses the nearby resonance, forcing the planet's equatorial plane to depart from Charon's orbital plane. The mutual tilt can reach as much as 3 degrees after integrating over 8.4 x 10(6) years, depending upon how close Pluto is to the resonance and the supply of volatiles. The second resonance is due to the Sun's traveling above and below Charon's orbital plane; it has a period half that of the eccentricity resonance. Reaching this half-Plutonian-year resonance requires a much larger but still theoretically possible amount of volatiles. In this case the departure of Charon from an equatorial orbit is similar to1 degrees after integrating for 5.6 x 10(6) years. The calculations ignore libration and tidal friction. It is not presently known how large the mutual tilt can grow over the age of the solar system, but It is probably less than similar to4 degrees. If so, then observing such small angles from a Pluto flyby mission would be difficult. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Geodynam Branch, Greenbelt, MD 20771 USA. RP Rubincam, DP (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Geodynam Branch, Code 921, Greenbelt, MD 20771 USA. RI Rubincam, David/D-2918-2012 NR 26 TC 6 Z9 6 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD NOV 25 PY 2000 VL 105 IS E11 BP 26745 EP 26755 DI 10.1029/2000JE001273 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 376AL UT WOS:000165435600005 ER PT J AU Stofan, ER Anderson, SW Crown, DA Plaut, JJ AF Stofan, ER Anderson, SW Crown, DA Plaut, JJ TI Emplacement and composition of steep-sided domes on Venus SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MOUNT-ST-HELENS; MEDICINE LAKE HIGHLAND; UNZEN VOLCANO JAPAN; LAVA FLOW SURFACES; PANCAKE DOMES; MAGELLAN DATA; TEXTURAL CONSTRAINTS; RADAR SCATTERING; GRAVITY CURRENTS; RHYOLITE FLOWS AB Steep-sided domes on Venus have surface characteristics that can provide information on their emplacement, including relatively smooth upper surfaces, radial and polygonal fracture patterns, and pits. These characteristics indicate that domes have surface crusts which are relatively unbroken, have mobile interiors after emplacement, and preserve fractures from only late in their history in response to endogenous growth or sagging of the dome surface. We have calculated the time necessary to form a 12-cm-thick crust for basalt and rhyolite under current terrestrial and Venusian ambient conditions. A 12-cm-thick crust will form in all cases in < 10 hours. Although Venusian lava flows should develop a brittle carapace during emplacement, only late-stage brittle fractures are preserved at steep-sided domes. We favor an emplacement model where early-formed surface crusts are entrained or continually annealed as they deform to accommodate dome growth. Entrainment and annealing of fractures are not mutually exclusive processes and thus may both be at work during steep-sided dome emplacement. Our results are most consistent with basaltic compositions, as rhyolitic lavas would quickly form thick crusts which would break into large blocks that would be difficult to entrain or anneal. However, if Venus has undergone large temperature excursions in the past (producing ambient conditions of 800-1000 K [e.g., Bullock and Grinspoon, 1996, 1998]), rhyolitic lavas would be unable to form crusts at high surface temperatures and could produce domes with surface characteristics consistent with those of Venusian steep-sided domes. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Pittsburgh, Dept Geol & Planetary Sci, Pittsburgh, PA 15260 USA. Black Hills State Univ, Spearfish, SD 57799 USA. RP Stofan, ER (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM ellen.r.stofan@jpl.nasa.gov NR 100 TC 29 Z9 31 U1 1 U2 6 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 NOV 25 PY 2000 VL 105 IS E11 BP 26757 EP 26771 DI 10.1029/1999JE001206 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 376AL UT WOS:000165435600006 ER PT J AU Crider, DH Vondrak, RR AF Crider, DH Vondrak, RR TI The solar wind as a possible source of lunar polar hydrogen deposits SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MOON; ICE; ATMOSPHERE AB We investigate the solar wind as a source for the deposits of hydrogen at the lunar poles. We create a Monte Carlo model that simulates the migration of atmospheric particles through the lunar exosphere. Making the model general enough to incorporate any physical process that might affect the particles, we develop a tool that estimates the number and form of particles that reach and stick to lunar cold traps. Each particle is allowed to follow a series of ballistic trajectories as it hops around the surface of the Moon. We trace the path of the particle until it is removed from the system by photo-processes such as ionization or dissociation, by thermal escape,or by reaching a cold trap. Accumulating statistics on the outcomes for various input particles, we determine the amount and form of hydrogen able to migrate to the lunar cold traps over time for a typical solar wind input flux. We find that although the fraction of hydrogen delivered to the Moon that ultimately reaches the poles is small, a slow steady source like the solar wind has provided enough hydrogen over 83 Myr to account for the observed deposits. Also, we find that an enrichment in the [D/H] ratio occurs by the migration process. The amount of fractionation is dependent on the molecular form of the migrating hydrogen. Atomic deuterium/hydrogen is enriched by a factor of 4 over the delivered fraction by the migration process. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Crider, DH (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RI Hurley, Dana/F-4488-2015 OI Hurley, Dana/0000-0003-1052-1494 NR 25 TC 70 Z9 71 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD NOV 25 PY 2000 VL 105 IS E11 BP 26773 EP 26782 DI 10.1029/2000JE001277 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 376AL UT WOS:000165435600007 ER PT J AU Berkovich, S Lapir, GM Mack, M AF Berkovich, S Lapir, GM Mack, M TI A bit-counting algorithm using the frequency division principle SO SOFTWARE-PRACTICE & EXPERIENCE LA English DT Article DE bit counting; bit-parallelism; document retrieval AB The paper addresses the omnipresent problem of bit counting. This problem is of particular importance for information systems where the choice of a rational access strategy may require repeated evaluation of the cardinalities of retrieved sets of data items. There are several different methods available to implement this procedure, which involve shifting, table look-up, exploiting the properties of fixed point arithmetic, and manipulations with bitwise logical operations.This paper presents a novel approach to the organization of bit counting based on the principle of frequency division (FD). The developed algorithm emulates a set of 32 binary counters using the bit-parallelism of computer word operations. The overflowing bits generated by these counters at a lower frequency are processed with the arithmetic-logic method, which is most efficient for sparse binary vectors. The suggested FD procedure is one of the fastest among the known, widely available procedures for bit counting. In future computers, with 64-bit words and larger, the gain in speed due to the FD technique will be higher, and the performance of this software could be comparable to that of specialized hardware. Copyright (C) 2000 John Wiley & Sons, Ltd. C1 George Washington Univ, Sch Engn & Appl Sci, Dept Comp Sci, Washington, DC 20052 USA. SER Syst AG, D-53577 Neustadt, Germany. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Berkovich, S (reprint author), George Washington Univ, Sch Engn & Appl Sci, Dept Comp Sci, Washington, DC 20052 USA. NR 7 TC 4 Z9 4 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0038-0644 J9 SOFTWARE PRACT EXPER JI Softw.-Pract. Exp. PD NOV 25 PY 2000 VL 30 IS 14 BP 1531 EP 1540 DI 10.1002/1097-024X(20001125)30:14<1531::AID-SPE347>3.0.CO;2-A PG 10 WC Computer Science, Software Engineering SC Computer Science GA 374AP UT WOS:000165322500001 ER PT J AU Cooke, DE Andersen, P AF Cooke, DE Andersen, P TI Automatic parallel control structures in SequenceL SO SOFTWARE-PRACTICE & EXPERIENCE LA English DT Article DE high level language; automatic parallelisms; executable specifications AB SequenceL is a language that provides declarative constructs for non-scalar processing. Rather than specifying program control structures that, in turn, imply a data product, the problem solver specifies a data product, and the control structures to produce or process the data product are implied. Although SequenceL has been previously introduced in two papers (Cooke, DE. An Introduction to SequenceL: A language to experiment with constructs for processing nonscalars, Software-Practice and Experience 1996; 26(11):1205-1246; and Cooke, D, SequenceL Provides a Different way to View Programming. Computer Languages 1998; 24:1-32), recent improvements to the language have indicated that parallel control structures are also implied by the SequenceL problem solutions. This paper focuses on these recent advances. Copyright (C) 2000 John Wiley & Sons, Ltd. C1 Texas Tech Univ, Dept Comp Sci, Lubbock, TX 79409 USA. NASA, Ames Res Ctr, Intelligent Syst Program, Moffett Field, CA 94035 USA. RP Cooke, DE (reprint author), Texas Tech Univ, Dept Comp Sci, Box 43104, Lubbock, TX 79409 USA. NR 14 TC 8 Z9 8 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0038-0644 J9 SOFTWARE PRACT EXPER JI Softw.-Pract. Exp. PD NOV 25 PY 2000 VL 30 IS 14 BP 1541 EP 1570 DI 10.1002/1097-024X(20001125)30:14<1541::AID-SPE350>3.0.CO;2-T PG 30 WC Computer Science, Software Engineering SC Computer Science GA 374AP UT WOS:000165322500002 ER PT J AU Harrison, C Adamson, DH Cheng, ZD Sebastian, JM Sethuraman, S Huse, DA Register, RA Chaikin, PM AF Harrison, C Adamson, DH Cheng, ZD Sebastian, JM Sethuraman, S Huse, DA Register, RA Chaikin, PM TI Mechanisms of ordering in striped patterns SO SCIENCE LA English DT Article ID BLOCK-COPOLYMER MICROSTRUCTURE; SWIFT-HOHENBERG EQUATION; DIBLOCK COPOLYMERS; DYNAMICS; ANNIHILATION; LITHOGRAPHY AB We have studied the ordering dynamics of the striped patterns of a single layer of cylindrical block copolymer microdomains in a thin film. By tracking disclinations during annealing with time-lapse atomic force microscopy, we observe a dominant mechanism of disclination annihilation involving three or four disclinations (quadrupoles). Pairwise disclination annihilation events are suppressed as a result of the topological constraints in this system. The kinetic scaling laws with exponents observed here are consistent with topologically allowed annihilation events involving multiple disclinations. The results provide insight into two-dimensional pattern formation and may lead to the successful application of block copolymer lithography. C1 Princeton Univ, Dept Phys, Princeton, NJ 08544 USA. Princeton Univ, Princeton Mat Inst, Princeton, NJ 08544 USA. Princeton Univ, Dept Chem Engn, Princeton, NJ 08544 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Harrison, C (reprint author), Princeton Univ, Dept Phys, Princeton, NJ 08544 USA. RI Adamson, Douglas/C-8721-2009 NR 27 TC 254 Z9 256 U1 8 U2 58 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD NOV 24 PY 2000 VL 290 IS 5496 BP 1558 EP 1560 DI 10.1126/science.290.5496.1558 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 376EX UT WOS:000165446200045 PM 11090350 ER PT J AU Pittard, JM Stevens, IR Corcoran, MF Gayley, KG Marchenko, SV Rauw, G AF Pittard, JM Stevens, IR Corcoran, MF Gayley, KG Marchenko, SV Rauw, G TI Coordinated monitoring of the eccentric O-star binary Iota Orionis: the X-ray analysis SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : general; stars : early-type; stars : individual : Iota Orionis (HD 37043); X-rays : stars ID COLLIDING STELLAR WINDS; ROSAT HRI OBSERVATIONS; V444 CYGNI; SPECTROSCOPIC SEARCH; RADIO OBSERVATIONS; ASCA OBSERVATIONS; MASSIVE BINARIES; MAIN-SEQUENCE; NEBULA REGION; HOT STARS AB We analyse two ASCA observations of the highly eccentric O9 III+B1 III binary Iota Orionis obtained at periastron and apastron. Based on the assumption of a strong colliding-wind shock between the stellar components, we expected to see significant variation in the X-ray emission between these phases. The observations proved otherwise: the X-ray luminosities and spectral distributions were remarkably similar. The only noteworthy feature in the X-ray data was the hint of a proximity effect during periastron passage. Although this 'flare' is of relatively low significance, it is supported by the notable proximity effects seen in the optical, and the phasing of the X-ray and optical events is in very good agreement. However, other interpretations are also possible. In view of the degradation of the SIS instrument and source contamination in the GIS data we discuss the accuracy of these results, and also analyse archival ROSAT observations. We investigate why we do not see a clear colliding-wind signature. A simple model shows that the wind attenuation to the expected position of the shock apex is negligible throughout the orbit, which poses the puzzling question of why the expected 1/D variation (i.e. a factor of 7.5) in the intrinsic luminosity is not seen in the data. Two scenarios are proposed: either the colliding-wind emission is unexpectedly weak such that intrinsic shocks in the winds dominate the emission, or, alternatively, the emission observed is colliding-wind emission but in a more complex form than we would naively expect. Complex hydrodynamical models are then analysed. Despite strongly phase-variable emission from the models, both are consistent with the observations. We find that if the mass-loss rates of the stars are low then intrinsic wind shocks could dominate the emission. However, when we assume higher mass-loss rates of the stars, we find that the observed emission could also be consistent with a purely colliding-wind origin. A summary of the strengths and weaknesses of each interpretation is presented. To distinguish between the different models X-ray observations with improved phase coverage will be necessary. C1 Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. Univ Leeds, Dept Phys & Astron, Leeds LS2 9JT, W Yorkshire, England. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Univ Iowa, Iowa City, IA 52245 USA. Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada. Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. RP Pittard, JM (reprint author), Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. OI Pittard, Julian/0000-0003-2244-5070 NR 63 TC 15 Z9 15 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD NOV 21 PY 2000 VL 319 IS 1 BP 137 EP 153 DI 10.1046/j.1365-8711.2000.03804.x PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 383VN UT WOS:000165905000011 ER PT J AU Brown, DW Chandler, CJ Carlstrom, JE Hills, RE Lay, OP Matthews, BC Richer, JS Wilson, CD AF Brown, DW Chandler, CJ Carlstrom, JE Hills, RE Lay, OP Matthews, BC Richer, JS Wilson, CD TI A submillimetre survey for protostellar accretion discs using the JCMT-CSO interferometer SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE circumstellar matter; stars : evolution; stars : formation ID YOUNG STELLAR OBJECTS; HERBIG-HARO OBJECTS; CIRCUMSTELLAR DISKS; DENSE CORES; DARK CLOUDS; PROTOPLANETARY DISKS; MOLECULAR OUTFLOW; EXCITING SOURCE; PROPER MOTIONS; STAR-FORMATION AB We present a submillimetre continuum survey for accretion discs around seven embedded protostars in the Perseus and Serpens molecular clouds. Observations were made at frequencies between 339 and 357 GHz using the James Clerk Maxwell Telescope-Caltech Submillimeter Observatory single-baseline interferometer on Mauna Kea, Hawaii. All the objects in our survey show compact dust emission on scales less than or similar to1 arcsec, assumed to arise in a circumstellar accretion disc. We compare the properties of this compact component with evolutionary indicators, such as the ratio of compact to extended emission, and bolometric temperature. We find that discs of mass similar to0.01M(circle dot) have formed by the Class 0 stage, and that similar mass discs are observed in Class I and Class II sources. A trend is observed whereby the ratio of compact to extended emission in our sources increases from Class 0 to Class II sources. For three of the objects in the survey, NGC 1333 IRAS2:CR1 and SVS13 in Perseus, and FIRS1 in Serpens, the signal-to-noise ratio is sufficient to allow us to model the brightness distributions with elliptical Gaussian and power-law disc models. The Gaussian fits give semimajor half-power radii of approximately 90 to 140 au, at the assumed distance of 350 pc to the Perseus and Serpens clouds. C1 Univ Cambridge, Cavendish Lab, Cavendish Astrophys Grp, Cambridge CB3 0HE, England. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. McMaster Univ, Dept Phys & Astron, Hamilton, ON L8S 4M1, Canada. RP Brown, DW (reprint author), Univ Cambridge, Cavendish Lab, Cavendish Astrophys Grp, Madingley Rd, Cambridge CB3 0HE, England. NR 58 TC 29 Z9 29 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD NOV 21 PY 2000 VL 319 IS 1 BP 154 EP 162 DI 10.1046/j.1365-8711.2000.03805.x PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 383VN UT WOS:000165905000012 ER PT J AU Baykal, A Strohmayer, T Swank, J Alpar, MA Stark, MJ AF Baykal, A Strohmayer, T Swank, J Alpar, MA Stark, MJ TI Differences between the two anomalous X-ray pulsars: variations in the spin-down rate of 1E 1048.1-5937 and an extended interval of quiet spin-down in 1E 2259+586 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE accretion, accretion discs; binaries : general; stars : individual : 1E 1048.1-5937; stars : individual : 1E 2259+586; stars : low-mass, brown dwarfs ID NEUTRON-STARS; CRAB PULSAR; ACCRETION; 1E-2259+586; EMISSION; NOISE AB We analysed the Rossi X-ray Timing Explorer (RXTE) archival data of 1E 1048.1-5937 covering a time-span of more than one year. The spin-down rate of this source decreases by similar to 30 per cent during the observation. We could not resolve the X-ray flux variations because of contamination by eta Carinae. We find that the level of pulse frequency fluctuations of 1E 1048.1-5937 is consistent with typical noise levels of accretion-powered pulsars. Recent RXTE observations of 1E 2259+586 have shown a constant spin-down with a very low upper limit on timing noise. We used the RXTE archival X-ray observations of 1E 2259+586 to show that the intrinsic X-ray luminosity times-series is also stable, with an rms fractional variation of less than 15 per cent. The source could have been in a quiet phase of accretion with a constant X-ray luminosity and spin-down rate. C1 Middle E Tech Univ, Dept Phys, TR-06531 Ankara, Turkey. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Sabanci Univ, Dept Phys, Istanbul, Turkey. Denison Univ, Dept Phys & Astron, Granville, OH 43023 USA. RP Baykal, A (reprint author), Middle E Tech Univ, Dept Phys, TR-06531 Ankara, Turkey. RI Swank, Jean/F-2693-2012 NR 37 TC 9 Z9 9 U1 0 U2 2 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD NOV 21 PY 2000 VL 319 IS 1 BP 205 EP 208 DI 10.1046/j.1365-8711.2000.03845.x PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 383VN UT WOS:000165905000015 ER PT J AU Cowan, TE Roth, M Johnson, J Brown, C Christl, M Fountain, W Hatchett, S Henry, EA Hunt, AW Key, MH MacKinnon, A Parnell, T Pennington, DM Perry, MD Phillips, TW Sangster, TC Singh, M Snavely, R Stoyer, M Takahashi, Y Wilks, SC Yasuike, K AF Cowan, TE Roth, M Johnson, J Brown, C Christl, M Fountain, W Hatchett, S Henry, EA Hunt, AW Key, MH MacKinnon, A Parnell, T Pennington, DM Perry, MD Phillips, TW Sangster, TC Singh, M Snavely, R Stoyer, M Takahashi, Y Wilks, SC Yasuike, K TI Intense electron and proton beams from PetaWatt laser-matter interactions SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT International Symposium on New Visions in Laser-Beam Interactions CY OCT 11-15, 1999 CL TOKYO, JAPAN SP Fdn High Energy Accelerator Sci, Atom Energy Soc Japan, Japan IBM, Hitachi Zosen Corp, AMSC Co Ltd, BM Ind, IDX Corp, Saitou Shouten, Sumitomo Heavy Ind Ltd, Kantou Informat Serv Co ID HOT-ELECTRONS; PLASMA; PULSES AB Recent experiments at the LLNL Petawatt Laser have demonstrated the generation of intense, high-energy beams of electrons and ions from the interaction of ultra-intense laser light with solid targets. The focused laser intensities are as high as 6 x 10(20) W/cm(2), at which point the quiver energies of the target electrons extend to similar to 10 MeV. In this new, fully relativistic regime of laser-plasma interactions, nuclear processes become important and nuclear techniques are required to diagnose the high-energy particle production. We describe recent experiments in which we have observed electrons accelerated to 100 MeV, photo-nuclear fission, positron-electron pair creation, monoenergetic electron jets and intense beams of protons emitted from the back surface of a laser-irradiated target. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Calif Lawrence Livermore Natl Lab, Dept Phys, Livermore, CA 94550 USA. Gesell Schwerionenforsch, Darmstadt, Germany. George C Marshall Space Flight Ctr, Huntsville, AL 35899 USA. Harvard Univ, Cambridge, MA 02138 USA. Univ Alabama, Huntsville, AL 35899 USA. Osaka Univ, Inst Laser Engn, Osaka, Japan. RP Cowan, TE (reprint author), Univ Calif Lawrence Livermore Natl Lab, Dept Phys, L-280,POB 808, Livermore, CA 94550 USA. RI MacKinnon, Andrew/P-7239-2014; Cowan, Thomas/A-8713-2011 OI MacKinnon, Andrew/0000-0002-4380-2906; Cowan, Thomas/0000-0002-5845-000X NR 18 TC 47 Z9 47 U1 0 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD NOV 21 PY 2000 VL 455 IS 1 BP 130 EP 139 DI 10.1016/S0168-9002(00)00720-8 PG 10 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 377LE UT WOS:000165514400024 ER PT J AU Goodrich, DC Chehbouni, A Goff, B MacNish, B Maddock, T Moran, S Shuttleworth, WJ Williams, DG Watts, C Hipps, LH Cooper, DI Schieldge, J Kerr, YH Arias, H Kirkland, M Carlos, R Cayrol, P Kepner, W Jones, B Avissar, R Begue, A Bonnefond, JM Boulet, G Branan, B Brunel, JP Chen, LC Clarke, T Davis, MR DeBruin, H Dedieu, G Elguero, E Eichinger, WE Everitt, J Garatuza-Payan, J Gempko, VL Gupta, H Harlow, C Hartogensis, O Helfert, M Holifield, C Hymer, D Kahle, A Keefer, T Krishnamoorthy, S Lhomme, JP Lagouarde, JP Lo Seen, D Luquet, D Marsett, R Monteny, B Ni, W Nouvellon, Y Pinker, R Peters, C Pool, D Qi, J Rambal, S Rodriguez, J Santiago, F Sano, E Schaeffer, SM Schulte, M Scott, R Shao, X Snyder, KA Sorooshian, S Unkrich, CL Whitaker, M Yucel, I AF Goodrich, DC Chehbouni, A Goff, B MacNish, B Maddock, T Moran, S Shuttleworth, WJ Williams, DG Watts, C Hipps, LH Cooper, DI Schieldge, J Kerr, YH Arias, H Kirkland, M Carlos, R Cayrol, P Kepner, W Jones, B Avissar, R Begue, A Bonnefond, JM Boulet, G Branan, B Brunel, JP Chen, LC Clarke, T Davis, MR DeBruin, H Dedieu, G Elguero, E Eichinger, WE Everitt, J Garatuza-Payan, J Gempko, VL Gupta, H Harlow, C Hartogensis, O Helfert, M Holifield, C Hymer, D Kahle, A Keefer, T Krishnamoorthy, S Lhomme, JP Lagouarde, JP Lo Seen, D Luquet, D Marsett, R Monteny, B Ni, W Nouvellon, Y Pinker, R Peters, C Pool, D Qi, J Rambal, S Rodriguez, J Santiago, F Sano, E Schaeffer, SM Schulte, M Scott, R Shao, X Snyder, KA Sorooshian, S Unkrich, CL Whitaker, M Yucel, I TI Preface paper to the Semi-Arid Land-Surface-Atmosphere (SALSA) Program special issue SO AGRICULTURAL AND FOREST METEOROLOGY LA English DT Article DE interdisciplinary; semi-arid; land-surface-atmosphere; SALSA; water balance; energy balance; ecological diversity AB The Semi-Arid Land-Surface-Atmosphere Program (SALSA) is a multi-agency, multi-national research effort that seeks to evaluate the consequences of natural and human-induced environmental change in semi-arid regions. The ultimate goal of SALSA is to advance scientific understanding of the semi-arid portion of the hydrosphere-biosphere interface in order to provide reliable information for environmental decision making. SALSA approaches this goal through a program of long-term, integrated observations, process research, modeling, assessment, and information management that is sustained by cooperation among scientists and information users. In this preface to the SALSA special issue, general program background information and the critical nature of semi-arid regions is presented. A brief description of the Upper San Pedro River Basin, the initial location for focused SALSA research follows. Several overarching research objectives under which much of the interdisciplinary research contained in the special issue was undertaken are discussed. Principal methods, primary research sites and data collection used by numerous investigators during 1997-1999 are then presented. Scientists from about 20 US, five European (four French and one Dutch), and three Mexican agencies and institutions have collaborated closely to make the research leading to this special issue a reality. The SALSA Program has served as a model of interagency cooperation by breaking new ground in the approach to large scale interdisciplinary science with relatively limited resources. Published by Elsevier Science B.V. C1 USDA ARS, SW Watershed Res Ctr, Tucson, AZ 85719 USA. IRD, IMADES, Hermosillo, Sonora, Mexico. Univ Arizona, Tucson, AZ USA. USDA ARS, Water Conservat Lab, Phoenix, AZ USA. Utah State Univ, Logan, UT 84322 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM USA. CESBIO, Toulouse, France. CIRAD, Montpellier, France. Univ Iowa, Iowa City, IA USA. AUW, Wageningen, Netherlands. CNRS, CEFE, Montpellier, France. USDA ARS, Weslaco, TX 78596 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. INRA, Bordeaux, France. USGS, WRD, Tucson, AZ USA. US EPA, Las Vegas, NV 89193 USA. Audubon Res Ranch, Elgin, AZ USA. Rutgers State Univ, New Brunswick, NJ 08903 USA. Univ Maryland, College Pk, MD 20742 USA. RP Goodrich, DC (reprint author), USDA ARS, SW Watershed Res Ctr, Tucson, AZ 85719 USA. RI Lo Seen, Danny/C-2679-2008; Pinker, Rachel/F-6565-2010; begue, agnes/A-5718-2011; Gupta, Hoshin/D-1642-2010; sorooshian, soroosh/B-3753-2008; Schaeffer, Sean/G-5071-2012; Elguero, Eric/J-3014-2012; Goodrich, David/B-1763-2009; Williams, David/A-6407-2014; Lhomme, Jean Paul /G-7236-2015; Boulet, Gilles/C-3067-2013; Nouvellon, Yann/C-9295-2016; OI Lo Seen, Danny/0000-0002-7773-2109; begue, agnes/0000-0002-9289-1052; Gupta, Hoshin/0000-0001-9855-2839; sorooshian, soroosh/0000-0001-7774-5113; Goodrich, David/0000-0001-7735-1448; Williams, David/0000-0003-3627-5260; Boulet, Gilles/0000-0002-3905-7560; Hipps, Lawrence/0000-0002-7658-8571; Nouvellon, Yann/0000-0003-1920-3847; rambal, serge/0000-0001-5869-8382; Schaeffer, Sean/0000-0002-9684-2952 NR 56 TC 44 Z9 45 U1 0 U2 10 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 NOV 20 PY 2000 VL 105 IS 1-3 BP 3 EP 20 DI 10.1016/S0168-1923(00)00178-7 PG 18 WC Agronomy; Forestry; Meteorology & Atmospheric Sciences SC Agriculture; Forestry; Meteorology & Atmospheric Sciences GA 377JQ UT WOS:000165510800002 ER PT J AU Moran, MS Hymer, DC Qi, JG Sano, EE AF Moran, MS Hymer, DC Qi, JG Sano, EE TI Soil moisture evaluation using multi-temporal synthetic aperture radar (SAR) in semiarid rangeland SO AGRICULTURAL AND FOREST METEOROLOGY LA English DT Article DE soil moisture; synthetic aperture radar; semiarid rangeland ID MICROWAVE; MANAGEMENT AB There have been several efforts to utilize satellite-based synthetic aperture radar (SAR) measurements to determine surface soil moisture (to 5 cm) conditions of rangeland regions. The results have been mixed since the relation between the SAR signal and surface soil moisture is confounded by variations in topographic features, surface roughness and vegetation density. We designed an experiment to investigate the sensitivity of C-band SAR backscatter (sigma (0)) to surface soil moisture (theta (s)) in a semiarid rangeland and to test a data-fusion approach based on both optical (Landsat TM) and radar (ERS-2 SAR) measurements to improve regional estimates of surface soil moisture content. The data-fusion approach [Sano, E.E. 1997. Sensitivity analysis of C- and Ku-band synthetic aperture radar data to soil moisture content in a semiarid regions. Ph.D. Dissertation. University of Arizona, AZ] utilized the difference between dry- and wet-season SAR sigma (0) to normalize roughness effects, and utilized surface reflectance in optical wavelengths to account for differences in vegetation density. We focused the study on three flat, uniformly vegetated sites of known surface roughness, monitored variations in surface soil moisture, vegetation density and SAR signal over time, and obtained eight optical/SAR image pairs throughout the dry and wet seasons. For these sparsely vegetated sites during this dry year (1997), we found that the SAR signal was not significantly attenuated by sparse green vegetation cover (green leaf area index ( 0.35) and dense standing brown vegetation cover (brown leaf area index up to 1.5). Consequently, the optical data was not required for this application, and the approach could be implemented by simply taking the difference between the dry- and wet-season SAR sigma (0) (sigma (0) - sigma (0)(dry)). For a data set of eight dates at three study sites, we confirmed that the relation between ERS-2 C-band SAR sigma (0) and theta (s) was weak (r(2) = 0.27); yet for the same data set, that the relation between sigma (0) - sigma (0)(dry) and theta (s) was strong and significant (r(2) = 0.93). This study also raised two concerns: (1) the overall sensitivity of SAR sigma (0) to theta (s) was relatively low, and (2) the approach required a high level of accuracy in the estimate of green leaf area level that may not be obtainable with standard optical remote sensing algorithms. In any case, the positive results from this study should encourage the use of a multi-temporal SAR and optical/SAR fusion for monitoring semiarid range conditions, and improving management of scarce resources. Published by Elsevier Science B.V. C1 USDA ARS, US Water Conservat Lab, Tucson, AZ 85719 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Michigan State Univ, E Lansing, MI 48824 USA. EMBRAPA, CPAC, Planaltina, DF, Brazil. RP Moran, MS (reprint author), USDA ARS, US Water Conservat Lab, Tucson, AZ 85719 USA. EM moran@tucson.ars.ag.gov NR 16 TC 105 Z9 115 U1 1 U2 26 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 NOV 20 PY 2000 VL 105 IS 1-3 BP 69 EP 80 PG 12 WC Agronomy; Forestry; Meteorology & Atmospheric Sciences SC Agriculture; Forestry; Meteorology & Atmospheric Sciences GA 377JQ UT WOS:000165510800006 ER PT J AU Reichardt, J AF Reichardt, J TI Error analysis of Raman differential absorption lidar ozone measurements in ice clouds SO APPLIED OPTICS LA English DT Article ID POLAR STRATOSPHERIC CLOUDS; MICROPHYSICAL PROPERTIES; CIRRUS CLOUDS; MULTIPLE-SCATTERING; PINATUBO AEROSOL; NORTHERN MIDLATITUDES; TROPOSPHERIC OZONE; VOLCANIC AEROSOLS; TROPOPAUSE REGION; PHASE FUNCTIONS AB A formalism for the error treatment of lidar ozone measurements with the Raman differential absorption lidar technique is presented. In the presence of clouds wavelength-dependent multiple scattering and cloud-particle extinction are the main sources of systematic errors in ozone measurements and necessitate a correction of the measured ozone profiles. Model calculations are performed to describe the influence of cirrus and polar stratospheric clouds on the ozone. It is found that it is sufficient to account for cloud-particle scattering and Rayleigh scattering in and above the cloud; boundary-layer aerosols and the atmospheric column below the cloud can be neglected for the ozone correction. Furthermore, if the extinction coefficient of the cloud is greater than or similar to0.1 km(-1), the effect in the cloud is proportional to the effective particle extinction and to a particle correction function determined in the limit of negligible molecular scattering. The particle correction function depends on the scattering behavior of the cloud particles, the cloud geometric structure, and the lidar system parameters. Because of the differential extinction of Light that has undergone one or more small-angle scattering processes within the cloud, the cloud effect on ozone extends to altitudes above the cloud. The various influencing parameters imply that the particle-related ozone correction has to be calculated for each individual measurement. Examples of ozone measurements in cirrus clouds are discussed. (C) 2000 Optical Society of America OCIS codes: 010.3640, 280.1910, 010.4950, 290.1090, 290.4210, 290.5860. C1 GKSS Forschungszentrum Geesthacht GmbH, Inst Phys & Chem Analyt, D-21494 Geesthacht, Germany. RP Reichardt, J (reprint author), Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol,Lab Atmospheres, Code 916, Greenbelt, MD 20771 USA. EM reichardt@code916.gsfc.nasa.gov NR 59 TC 11 Z9 11 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD NOV 20 PY 2000 VL 39 IS 33 BP 6058 EP 6071 DI 10.1364/AO.39.006058 PG 14 WC Optics SC Optics GA 372WT UT WOS:000165257600002 PM 18354611 ER PT J AU Reichardt, J Bisson, SE Reichardt, S Weitkamp, C Neidhart, B AF Reichardt, J Bisson, SE Reichardt, S Weitkamp, C Neidhart, B TI Rotational vibrational-rotational Raman differential absorption lidar for atmospheric ozone measurements: methodology and experiment SO APPLIED OPTICS LA English DT Article ID ICE CLOUDS; TROPOSPHERIC OZONE; AEROSOL AB A single-laser Raman differential absorption lidar (DIAL) for ozone measurements in clouds is proposed. An injection-locked XeCl excimer laser serves as the radiation source. The ozone molecule number density is calculated from the differential absorption of the anti-Stokes rotational Raman return signals from molecular nitrogen and oxygen as the on-resonance wavelength and the vibrational-rotational Raman backscattering from molecular nitrogen or oxygen as the off-resonance wavelength. Model calculations show that the main advantage of the new rotational vibrational-rotational (RVR) Raman DIAL over conventional Raman DIAL is a 70-85% reduction in the wavelength-dependent effects of cloud-particle scattering on the measured ozone concentration; furthermore the complexity of the apparatus is reduced substantially. We describe a RVR Raman DIAL setup that uses a narrow-band interference-filter polychromator as the lidar receiver. Single-laser ozone measurements in the troposphere and lower stratosphere are presented, and it is shown that on further improvement of the receiver performance, ozone measurements in clouds are attainable with the filter-polychromator approach. (C) 2000 Optical Society of America OCIS codes: 010.3640, 280.1910, 290.5860, 010.4950, 290.1090, 290.4210. C1 GKSS Forschungszentrum Geesthacht GmbH, Inst Phys & Chem Analyt, D-21494 Geesthacht, Germany. Sandia Natl Labs, Livermore, CA 94551 USA. RP Reichardt, J (reprint author), Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Joint Ctr Earth Syst Technol,Lab Atmospheres, Code 916, Greenbelt, MD 20771 USA. EM reichardt@code916.gsfc.nasa.gov; sebisso@sandia.gov; claus.weitkamp@gkss.de; bernd.neidhart@gkss.de NR 17 TC 8 Z9 8 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD NOV 20 PY 2000 VL 39 IS 33 BP 6072 EP 6079 DI 10.1364/AO.39.006072 PG 8 WC Optics SC Optics GA 372WT UT WOS:000165257600003 PM 18354612 ER PT J AU Vermeulen, A Devaux, C Herman, M AF Vermeulen, A Devaux, C Herman, M TI Retrieval of the scattering and microphysical properties of aerosols from ground-based optical measurements including polarization. I. Method SO APPLIED OPTICS LA English DT Article ID SKY BRIGHTNESS MEASUREMENTS; SIZE DISTRIBUTIONS; EXTINCTION MEASUREMENTS; ATMOSPHERIC CORRECTION; PLANETARY ATMOSPHERES; MULTIPLE-SCATTERING; LIGHT-SCATTERING; REFRACTIVE-INDEX; PHASE FUNCTION; INVERSION AB A method has been developed for retrieving the scattering and microphysical properties of atmospheric aerosol from measurements of solar transmission, aureole, and angular distribution of the scattered and polarized sky light in the solar principal plane. Numerical simulations of measurements have been used to investigate the feasibility of the method and to test the algorithm's performance. It is shown that the absorption and scattering properties of an aerosol, i.e., the single-scattering albedo, the phase function, and the polarization for single scattering of incident unpolarized light, can be obtained by use of radiative transfer calculations to correct the values of scattered radiance and polarized radiance for multiple scattering, Rayleigh scattering, and the influence of ground. The method requires only measurement of the aerosol's optical thickness and an estimate of the ground's reflectance and does not need any specific assumption about properties of the aerosol. The accuracy of the retrieved phase function and polarization of the aerosols is examined at near-infrared wavelengths (e.g., 0.870 mum). The aerosol's microphysical properties (size distribution and complex refractive index) are derived in a second step. The real part of the refractive index is a strong function of the polarization, whereas the imaginary part is strongly dependent on the sky's radiance and the retrieved single-scattering albedo. It is demonstrated that inclusion of polarization data yields the real part of the refractive index. (C) 2000 Optical Society of America OCIS codes: 280.1310, 010.1110, 260.5430, 290.4210. C1 Univ Sci & Tech Lille, UMR 8518, Opt Atmospher Lab, Unite Format & Rech Phys, F-59655 Villeneuve Dascq, France. RP Vermeulen, A (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Code 923, Greenbelt, MD 20771 USA. EM anne@aeronet.gsfc.nasa.gov NR 38 TC 42 Z9 45 U1 1 U2 8 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD NOV 20 PY 2000 VL 39 IS 33 BP 6207 EP 6220 DI 10.1364/AO.39.006207 PG 14 WC Optics SC Optics GA 372WT UT WOS:000165257600020 PM 18354629 ER PT J AU Stevens, R Nguyen, C Cassell, A Delzeit, L Meyyappan, M Han, J AF Stevens, R Nguyen, C Cassell, A Delzeit, L Meyyappan, M Han, J TI Improved fabrication approach for carbon nanotube probe devices SO APPLIED PHYSICS LETTERS LA English DT Article ID MICROSCOPY TIPS; GROWTH AB An improved process is developed for simple and efficient fabrication of carbon nanotube probe devices. This process requires only two steps to make nanotube probes. First a nanotube cartridge is created using chemical vapor deposition, then the nanotubes are transferred from the cartridge to a device using an electric field. Multiwall nanotube probes are made into different device geometries in this approach. Their applications are illustrated by atomic force microscopy imaging of the surface of a terrestrial rock granule selected to simulate the morphology and consistency of a grain of Mars dust and nanolithography on a silicon substrate. [S0003-6951(00)04347-3]. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Stevens, R (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 13 TC 81 Z9 82 U1 0 U2 21 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD NOV 20 PY 2000 VL 77 IS 21 BP 3453 EP 3455 DI 10.1063/1.1328046 PG 3 WC Physics, Applied SC Physics GA 375JN UT WOS:000165395900046 ER PT J AU Scharf, CA Jahoda, K Treyer, M Lahav, O Boldt, E Piran, T AF Scharf, CA Jahoda, K Treyer, M Lahav, O Boldt, E Piran, T TI The 2-10 KeV X-ray background dipole and its cosmological implications SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; large-scale structure of universe; X-rays : general ID N-LOG S; LOCAL-GROUP; WIENER RECONSTRUCTION; LUMINOSITY FUNCTION; NEARBY GALAXIES; REDSHIFT SURVEY; ROSAT SURVEY; SKY SURVEY; MOTION; FLUCTUATIONS AB The hard X-ray (>2 keV) emission of the local and distant universe as observed with the HEAO I A-2 experiment is reconsidered in the context of large-scale cosmic structure. Using all-sky X-ray samples of active galactic nuclei (AGNs) and galaxy clusters, we remove the dominant local X-ray flux from within a redshift of similar to0.02. We evaluate the dipolar and higher order harmonic structure in four X-ray colors. The estimated dipole anisotropy of the unresolved flux appears to be consistent with a combination of the Compton-Getting effect due to the Local Group motion (dipole amplitude Delta = 0.0042) and remaining large-scale structure (0.0023 less than or similar to Delta less than or similar to 0.0085), in good agreement with the expectations of cold dark matter models. The observed anisotropy does, however, also suggest a nonnegligible Galactic contribution that is more complex than current, simple models of >2 keV Galactic X-ray emission. Comparison of the soft and hard color maps with a harmonic analysis of the 1.5 keV ROSAT all-sky data qualitatively suggests that at least a third of the faint, unresolved -18" scale structure in the HEAO I A-2 data may be Galactic in origin. However, the effect on measured flux dipoles is small (less than or similar to3%). We derive an expression for dipole anisotropy and acceleration and demonstrate how the dipole anisotropy of the distant X-ray frame can constrain the amplitude of bulk motions of the universe. From observed bulk motions over a local similar to 50 h(-1) Mpc radius volume, we determine 0.14 less than or similar to Omega (0.6)(0)/b(X)(0) less than or similar to 0.59, where Omega (0), is the universal density parameter and b(X)(0) is the present-epoch bias parameter, defined as the ratio of fluctuations in the X-ray source density and the mass density. C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Astron Spatiale Lab, F-13376 Marseille, France. Hebrew Univ Jerusalem, Racah Inst Phys, IL-91904 Jerusalem, Israel. Inst Astron, Cambridge CB3 0HA, England. RP Scharf, CA (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. RI Jahoda, Keith/D-5616-2012 NR 56 TC 27 Z9 27 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2000 VL 544 IS 1 BP 49 EP 62 DI 10.1086/317174 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 381FH UT WOS:000165751300006 ER PT J AU Blanton, M AF Blanton, M TI How stochastic is the relative bias between galaxy types? SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : general; large-scale structure of universe ID CAMPANAS REDSHIFT SURVEY; MORPHOLOGICAL SEGREGATION; LUMINOSITY FUNCTION; CATALOG; DENSITY AB Examining the nature of the relative clustering of different galaxy types can help tell us how galaxies formed. To measure this relative clustering, I perform a joint counts-in-cells analysis of galaxies of different spectral types in the Las Campanas Redshift Survey (LCRS). I develop a maximum-likelihood technique to fit for the relationship between the density fields of early- and late-type galaxies. This technique can directly measure nonlinearity and stochasticity in the biasing relation. At high significance, a small amount of stochasticity is measured, corresponding to a correlation coefficient r approximate to 0.87 on scales corresponding to 15 h(-1) Mpc spheres. A large proportion of this signal appears to derive from errors in the selection function, and a more realistic estimate finds r approximate to 0.95. These selection function errors probably account for the large stochasticity measured by Tegmark & Bromley, and may have affected measurements of very large-scale structure in the LCRS. Analysis of the data and of mock catalogs shows that the peculiar geometry, variable flux limits, and central surface brightness selection effects of the LCRS do not seem to cause the effect. C1 Princeton Univ Observ, Princeton, NJ 08544 USA. NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. RP Blanton, M (reprint author), Princeton Univ Observ, Peyton Hall, Princeton, NJ 08544 USA. NR 34 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2000 VL 544 IS 1 BP 63 EP 80 DI 10.1086/317198 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 381FH UT WOS:000165751300007 ER PT J AU Vennes, S Polomski, EF Lanz, T Thorstensen, JR Chayer, P Gull, TR AF Vennes, S Polomski, EF Lanz, T Thorstensen, JR Chayer, P Gull, TR TI Hubble Space Telescope imaging spectrograph observations of the hot white dwarf in the close binary Feige 24 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM : abundances; stars : abundances; stars : individual (Feige 24); ultraviolet : stars; white dwarfs ID LOCAL INTERSTELLAR-MEDIUM; BLANKETED MODEL ATMOSPHERES; EXTREME-ULTRAVIOLET SOURCE; ALL-SKY SURVEY; EFFECTIVE TEMPERATURES; RADIATIVE LEVITATION; MASS-DISTRIBUTION; HEAVY-ELEMENTS; EUV SPECTRUM; HST-GHRS AB We obtained and analyzed two Hubble Space Telescope Imaging Spectrograph spectra of the white dwarf in the DA plus dMe binary Feige 24. The spectra, obtained at orbital quadratures, provide new estimates of the white dwarf motion and gravitational redshift resulting in revised white dwarf parameters. An analysis of interstellar absorption lines reveals the presence of two clouds (+3.1 km s(-1), +17.6 km s(-1)) in the line of sight toward Feige 24; one of these clouds (+17.6 km s(-1)) is identified with the "local cloud." A study of the Ly alpha H I and D I interstellar medium lines shows that the deuterium-to-hydrogen abundance ratio (D/H = 1.3 x 10(-5)) is consistent with other measurements supporting a relative constancy of this ratio throughout the local interstellar medium. The total hydrogen column density measured with Ly alpha (log n(H) = 2.95 x 10(18) cm(-2)) is in agreement with EUV Lyman continuum flux measurements. Finally, we present a complete abundance pattern for the white dwarf demonstrating the predominance of iron and nickel over lighter elements. Residual ionization imbalance in the case of several elements, most notably in the case of O IV/O V, which cannot be explained by temperature or surface gravity variations, may indicate the presence of other atmospheric constituents, inhomogeneous stratification of oxygen in the photosphere, and/or remaining inaccuracies in the treatment of model atoms. The abundance patterns in Feige 24 and in the hot DA white dwarf G191-B2B are remarkably similar, indicating that the same processes are operating equally in both stars. C1 Univ Florida, Dept Astron, Gainesville, FL 32611 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA. Johns Hopkins Univ, Bloomberg Ctr Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Vennes, S (reprint author), Australian Natl Univ, Dept Math, Canberra, ACT 0200, Australia. RI Gull, Theodore/D-2753-2012; Vennes, Stephane/G-9903-2014 OI Gull, Theodore/0000-0002-6851-5380; NR 58 TC 27 Z9 27 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2000 VL 544 IS 1 BP 423 EP 436 DI 10.1086/317205 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 381FH UT WOS:000165751300037 ER PT J AU Bautista, MA Kallman, TR AF Bautista, MA Kallman, TR TI Recombination spectra of helium-like ions SO ASTROPHYSICAL JOURNAL LA English DT Article DE atomic processes; line : formation; X-rays : general ID HE-LIKE IONS; DOUBLY EXCITED-LEVELS; HYDROGENIC IONS; ELECTRON-IMPACT; COLLISION STRENGTHS; LINE-INTENSITIES; ATOMIC DATA; OSCILLATOR-STRENGTHS; OPACITY CALCULATIONS; RATE COEFFICIENTS AB We calculate the recombination spectra of the He-like ions He I, C v, N vI, O vII, Ne Ix, Mg xI, Si xIII, S xv, Ar xvII, Ca xIX, and Fe xxv. We include the following physical processes: radiative recombination, dielectronic recombination, three-body recombination, electron impact ionization, and collisional excitation by electrons, protons, and a-particles. The calculations also account for the effects of lowering of the continuum at high densities and high-density corrections to dielectronic recombination. From the populations of all levels in the recombined ions, we construct models for He-like ions for fast computation of their spectra. Every model includes 29 bound levels up to n = 5, a pair of "superlevels" that account for radiative and collisional cascades from highly excited levels, six doubly excited levels that account for the most important satellite lines, and a level that represents the hydrogenic recombining ion. The models are constructed in a way that allows for the correct approach to LTE under appropriate conditions. These models can simultaneously solve for the H/He-like ionization balance in photoionized or collisionally ionized plasmas and compute emission spectra, including the combined effects of radiative and dielectronic recombination, collisional excitation, photoionization from excited levels, fluorescence, and line trapping. The models can be used for any temperature between 100 and 10(9) K and electron densities of up to 10(18) cm(-3). The models can be used easily within spectral modeling codes or as stand-alone tools for spectral analysis. We present comparisons between the results of the present models and previous work. Significant differences are found between the present effective recombination rate coefficients to the n = 2 and those of previous estimates. Later, we study various emission-line ratio diagnostics under collisional ionization and photoionized conditions. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Bautista, MA (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NR 58 TC 47 Z9 47 U1 0 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2000 VL 544 IS 1 BP 581 EP 591 DI 10.1086/317206 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 381FH UT WOS:000165751300052 ER PT J AU Bregman, JD Hayward, TL Sloan, GC AF Bregman, JD Hayward, TL Sloan, GC TI Discovery of the 11.2 micron polycyclic aromatic hydrocarbon band in absorption toward Monoceros R2 IRS 3 SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM : lines and bands; ISM : molecules; stars : individual (Monoceros R2 IRS 3) ID INFRARED-SPECTROSCOPY; SPECTRA; FEATURES; R2/IRS-3; RINGS; PAHS AB Interpretation of the infrared emission bands is difficult because these bands likely arise from a mixture of ionized and neutral polycyclic aromatic hydrocarbon (PAH) molecules. Modeling the emission process is also difficult because the size distribution of the molecules, their ionization state and excitation, and the geometry of the emitting regions are generally unknown. If these molecular bands could be found in absorption, many of these factors would be eliminated, making it much easier to interpret the data. We have discovered an absorption band in Monoceros R2 IRS 3 centered at 11.25 mum that we identify with a C-H out-of-plane vibrational mode of PAH molecules. The shape and position of the band are very similar to that seen in emission in planetary nebulae, H II regions, and the interstellar medium. C1 NASA, Ames Res Ctr, Astrophys Branch, Moffett Field, CA 94035 USA. Gemini Observ, Hilo, HI 96720 USA. Boston Coll, Inst Sci Res, Chestnut Hill, MA 02467 USA. RP Bregman, JD (reprint author), NASA, Ames Res Ctr, Astrophys Branch, MS 245-6, Moffett Field, CA 94035 USA. NR 17 TC 31 Z9 31 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2000 VL 544 IS 1 BP L75 EP L78 DI 10.1086/317294 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 381GB UT WOS:000165753000017 ER PT J AU Wood, KS Ray, PS Bandyopadhyay, RM Wolff, MT Fritz, G Hertz, P Kowalski, MP Lovellette, MN Yentis, D Bloom, ED Giebels, B Godfrey, G Reilly, K Parkinson, PS Shabad, G Scargle, J AF Wood, KS Ray, PS Bandyopadhyay, RM Wolff, MT Fritz, G Hertz, P Kowalski, MP Lovellette, MN Yentis, D Bloom, ED Giebels, B Godfrey, G Reilly, K Parkinson, PS Shabad, G Scargle, J TI USA experiment and RXTE observations of a variable low-frequency quasi-periodic oscillation in XTE J1118+480 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; stars : individual (XTE J1118+480) ID RAY TIMING EXPLORER AB Using the USA Experiment on the Advanced Research and Global Observation Satellite and the Rossi X-Ray Timing Explorer, we have extensively observed the X-ray transient XTE J1118+480 during its recent outburst in 2000 April-June. We present detailed monitoring of the evolution of a low-frequency quasi-periodic oscillation (QPO) that drifts from 0.07 to 0.15 Hz during the outburst. We examine possible correlations of the QPO frequency with the flux and spectral characteristics of the source, and we compare this QPO with low-frequency QPOs observed in other black hole candidates. C1 USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. Stanford Linear Accelerator Ctr, Stanford, CA 94309 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Wood, KS (reprint author), USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. OI Ray, Paul/0000-0002-5297-5278 NR 16 TC 31 Z9 31 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 20 PY 2000 VL 544 IS 1 BP L45 EP L48 DI 10.1086/317287 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 381GB UT WOS:000165753000010 ER PT J AU Liu, J Riggs, HR Tessler, A AF Liu, J Riggs, HR Tessler, A TI A four-node, shear-deformable shell element developed via explicit Kirchhoff constraints SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article DE four-node quadrilateral shell element; sheer deformation theory; Kirchhoff constraints ID FINITE-ELEMENT; MEMBRANE; LOCKING AB An efficient, four-node quadrilateral shell element is formulated using a linear, first-order shear deformation theory. The bending part of the formulation is constructed from a cross-diagonal assembly of four three-node anisoparametric triangular plate elements, referred to as MIN3. Closed-form constraint equations, which arise from the Kirchhoff constraints in the thin-plate limit, are derived and used to eliminate the degrees-of-freedom associated with the 'internal' node of the cross-diagonal assembly. The membrane displacement held employs an Allman-type, drilling degrees-of-freedom formulation. The result is a displacement-based, fully integrated, four-node quadrilateral element, MIN4T, possessing six degrees-of-freedom at each node. Results for a set of validation plate problems demonstrate that the four-node MIN4T has similar robustness and accuracy characteristics as the original cross-diagonal assembly of MIN3 elements involving five nodes. The element performs well in both moderately thick and thin regimes, and it is free of shear locking. Shell validation results demonstrate superior performance of MIN4T over MINS, possibly as a result of its higher order interpolation of the membrane displacements. It is also noted that the bending formulation of MIN4T is kinematically compatible with the existing anisoparametric elements of the same order of approximation, which include a two-node Timoshenko beam element and a three-node plate element, MIN3. Copyright (C) 2000 John Wiley & Sons, Ltd. C1 Univ Hawaii Manoa, Dept Civil Engn, Honolulu, HI 96822 USA. NASA, Langley Res Ctr, Analyt & Computat Methods Branch, Hampton, VA 23681 USA. RP Riggs, HR (reprint author), Univ Hawaii Manoa, Dept Civil Engn, 2540 Dole St,Holmes Hall 383, Honolulu, HI 96822 USA. RI Tessler, Alexander/A-4729-2009 NR 22 TC 17 Z9 17 U1 1 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD NOV 20 PY 2000 VL 49 IS 8 BP 1065 EP 1086 DI 10.1002/1097-0207(20001120)49:8<1065::AID-NME992>3.0.CO;2-5 PG 22 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA 367LT UT WOS:000090064300004 ER PT J AU Chang, SC Wang, XY To, WM AF Chang, SC Wang, XY To, WM TI Application of the space-time conservation element and solution element method to one-dimensional convection-diffusion problems SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE space-time; flux conservation; conservation element; solution element; shocks ID SAINT-VENANT EQUATIONS AB In the space-time conservation element and solution element (CE/SE) method, the independent marching variables used comprise not only the mesh values of the physical dependent Variables but also, in contrast to a typical numerical method, the mesh values of the spatial derivatives of these physical variables. The use of the extra marching variables results from the need to construct the two-level, explicit and nondissipative schemes which are at the core of the CE/SE development. It also results from the need to minimize the stencil while maintaining accuracy. In this paper, using the 1D a-mu scheme as an example, the effect of this added complication on consistency, accuracy, and operation count is assessed. As part of this effort, an equivalent yet more efficient form of the a-mu scheme in which the independent marching variables are the local fluxes tied to each mesh point is introduced. Also, the intriguing relations that exist among the a-mu. Leapfrog, and DuFort-Frankel schemes are further explored. In addition, the redundancy of the Leapfrog, DuFort-Frankel, and Lax schemes and the remedy for this redundancy are discussed. This paper is concluded with the construction and evaluation of a CE/SE solver for the inviscid Burgers equation. (C) 2000 Academic Press. C1 NASA, Glenn Res Ctr, Taitech Inc, Cleveland, OH 44135 USA. NASA, Glenn Res Ctr, AP Solut Inc, Cleveland, OH 44135 USA. RP Chang, SC (reprint author), NASA, Glenn Res Ctr, Taitech Inc, Cleveland, OH 44135 USA. NR 23 TC 32 Z9 34 U1 0 U2 8 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD NOV 20 PY 2000 VL 165 IS 1 BP 189 EP 215 DI 10.1006/jcph.2000.6610 PG 27 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 375WB UT WOS:000165423300008 ER PT J AU Pan, LWL Hintsa, EJ Stone, EM Weinstock, EM Randel, WJ AF Pan, LWL Hintsa, EJ Stone, EM Weinstock, EM Randel, WJ TI The seasonal cycle of water vapor and saturation vapor mixing ratio in the extratropical lowermost stratosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID UPPER-TROPOSPHERIC WATER; GAS EXPERIMENT-II; HEMISPHERIC ASYMMETRIES; NASA ER-2; TRANSPORT; AIRCRAFT; AEROSOL; DISTRIBUTIONS; CIRCULATION; HYGROMETER AB Both in situ measurements and satellite remote sensing data show that water vapor in the extratropical lowermost stratosphere has a pronounced seasonal cycle, with a maximum in summer. In this paper we show that the seasonal cycles derived from satellite measurements by the Stratospheric Aerosol and Gas Experiment (SAGE) II and the Microwave Limb Sounder (MLS) and ER-2 aircraft measurements are in reasonable agreement when compared using potential vorticity (PV) and potential temperature (theta) binned monthly averages. The annual means and amplitudes of the water vapor seasonal cycle are derived from the SAGE II data for 320-360 It and 2-7 PV units (covering latitudes near and poleward of the tropopause). The high moisture content and the summer maxima indicate that the effect of transport from the troposphere across the extratropical tropopause can be seen in nearly the entire range examined and is more significant in the lower PV-theta bins. We further investigate mechanisms that control the amount and seasonal cycle of water vapor in the lowermost stratosphere. One important issue is whether local temperature near the extratropical tropopause limits isentropic transport of water vapor into the lowermost stratosphere, similar to the freeze-out of water vapor crossing the tropical tropopause. A quantitative comparison of saturation vapor mixing ratios (derived from National Centers for Environmental Prediction temperature analyses) with the water vapor measurements shows that the amount of water vapor near the extratropical tropopause is substantially lower than that given by saturation over ice. This demonstrates that local temperature effects do not set the upper limit of water vapor in this region. Analyses using ER-2 measurements confirm that although saturation and supersaturation do occur, on average, air near the extratropical tropopause is undersaturated. The seasonal cycle of the fraction of the overworld air in the lowermost stratosphere is inferred using the water vapor and saturation vapor mixing ratio climatology. C1 Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02138 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Pan, LWL (reprint author), Natl Ctr Atmospher Res, POB 3000, Boulder, CO 80307 USA. EM liwen@ucar.edu RI Pan, Laura/A-9296-2008; Randel, William/K-3267-2016 OI Pan, Laura/0000-0001-7377-2114; Randel, William/0000-0002-5999-7162 NR 32 TC 21 Z9 22 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 16 PY 2000 VL 105 IS D21 BP 26519 EP 26530 DI 10.1029/2000JD900401 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 375VH UT WOS:000165421600013 ER PT J AU Srinivasan, G Robock, A Entin, JK Luo, LF Vinnikov, KY Viterbo, P AF Srinivasan, G Robock, A Entin, JK Luo, LF Vinnikov, KY Viterbo, P CA AMIP Modeling Grp TI Soil moisture simulations in revised AMIP models SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SURFACE PARAMETERIZATION SCHEMES; ASIAN SUMMER MONSOON; INTERANNUAL VARIABILITY; ECMWF REANALYSIS; INTERCOMPARISON PROJECT; WETNESS PROJECT; WATER-BALANCE; LAND; CLIMATE; PRECIPITATION AB Soil moisture is important both in its influence on climate and for assessing impacts of future climate change. It is therefore necessary to simulate it correctly in global climate models. We have used the revisit simulations contributed by six of the Atmospheric Model Intercomparison Project 1 participating modeling groups to examine the impacts of model revisions, particularly the land surface representations, on soil moisture simulations, by comparing the simulations to actual soil moisture observations. The revised models do not show any systematic improvement in their ability to simulate observed seasonal variations of soil moisture over the regions studied. Many of the revised models continue to have a strong tendency toward dry soil conditions during Northern Hemisphere summer months, both globally and regionally. There are no indications of conceptually more realistic land surface representations producing better soil moisture simulations in the revised climate models. As the revised models continue to produce incorrect simulations of the seasonal cycle of regional precipitation, it is not possible to isolate the effect of land surface schemes on the simulations. The European Centre for Medium Range Weather Forecasts and National Centers for Environmental Prediction/National Center for Atmospheric Research reanalyses, however, which are driven by observed precipitation, do capture some of the observed interannual variability of soil moisture over Illinois. C1 Rutgers State Univ, Dept Environm Sci, New Brunswick, NJ 08901 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. European Ctr Medium Range Weather Forecasts, Reading RG2 9AX, Berks, England. Indian Meteorol Dept, Reg Meteorol Ctr, Bombay 400005, Maharashtra, India. NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Raytheon ITSS, Greenbelt, MD 20771 USA. Bur Meteorol Res Ctr, Melbourne, Vic, Australia. Ctr Natl Rech Meteorol, Toulouse, France. Dept Numer Math, Moscow, Russia. Geophys Fluid Dynam Lab, Princeton, NJ USA. Meteorol Dynam Lab, Paris, France. Yonsei Univ, Seoul 120749, South Korea. RP Srinivasan, G (reprint author), Rutgers State Univ, Dept Environm Sci, 14 Coll Farm Rd, New Brunswick, NJ 08901 USA. EM sriniren@vsnl.com; robock@envsci.rutgers.edu; jentin@dao.gsfc.nasa.gov; luo@envsci.rutgers.edu; kostya@atmos.umd.edu; p.viterbo@ecmwf.int RI Luo, Lifeng/C-8734-2009; Vinnikov, Konstantin/F-9348-2010; Viterbo, Pedro/B-7184-2008; Robock, Alan/B-6385-2016; OI Viterbo, Pedro/0000-0001-6587-3062; Robock, Alan/0000-0002-6319-5656 NR 43 TC 27 Z9 27 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD NOV 16 PY 2000 VL 105 IS D21 BP 26635 EP 26644 DI 10.1029/2000JD900443 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 375VH UT WOS:000165421600023 ER PT J AU Olsen, N Holme, R Hulot, G Sabaka, T Neubert, T Toffner-Clausen, L Primdahl, F Jorgensen, J Leger, JM Barraclough, D Bloxham, J Cain, J Constable, C Golovkov, V Jackson, A Kotze, P Langlais, B Macmillan, S Mandea, M Merayo, J Newitt, L Purucker, M Risbo, T Stampe, M Thomson, A Voorhies, C AF Olsen, N Holme, R Hulot, G Sabaka, T Neubert, T Toffner-Clausen, L Primdahl, F Jorgensen, J Leger, JM Barraclough, D Bloxham, J Cain, J Constable, C Golovkov, V Jackson, A Kotze, P Langlais, B Macmillan, S Mandea, M Merayo, J Newitt, L Purucker, M Risbo, T Stampe, M Thomson, A Voorhies, C TI Orsted initial field model SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Magnetic measurements taken by the Orsted satellite during geomagnetic quiet conditions around January 1, 2000 have been used to derive a spherical harmonic model of the Earth's magnetic field for epoch 2000.0. The maximum degree and order of the model is 19 for internal, and 2 for external, source fields; however, coefficients above degree 14 may not be robust. Such a detailed model exists for only one previous epoch, 1980. Achieved rms misfit is < 2 nT for the scalar intensity and < 3 nT for one of the vector components perpendicular to the magnetic field. For scientific purposes related to the Orsted mission, this model supercedes IGRF 2000. C1 Danish Space Res Inst, DK-2100 Copenhagen O, Denmark. Geoforschungszentrum Potsdam, D-14473 Potsdam, Germany. IPGP, Paris, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Danish Meteorol Inst, Copenhagen, Denmark. DTU, Inst Automat, Lyngby, Denmark. British Geol Survey, Edinburgh, Midlothian, Scotland. Harvard Univ, Cambridge, MA 02138 USA. Florida State Univ, Tallahassee, FL 32306 USA. Univ Calif San Diego, San Diego, CA 92103 USA. IZMIRAN, Troitsk 142092, Russia. Univ Leeds, Leeds LS2 9JT, W Yorkshire, England. Hermanus Magnet Observ, Hermanus, South Africa. Univ Copenhagen, Copenhagen, Denmark. RP Olsen, N (reprint author), Danish Space Res Inst, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark. RI Hulot, Gauthier/A-5627-2011; Constable, Catherine/F-7784-2010; Olsen, Nils/H-1822-2011; Voorhies, Coerte/D-4672-2012; Sabaka, Terence/D-5618-2012; MANDEA, Mioara/E-4892-2012; Langlais, Benoit/K-5366-2012 OI Constable, Catherine/0000-0003-4534-4977; Olsen, Nils/0000-0003-1132-6113; Langlais, Benoit/0000-0001-5207-304X NR 7 TC 89 Z9 96 U1 1 U2 11 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2000 VL 27 IS 22 BP 3607 EP 3610 DI 10.1029/2000GL011930 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 375TW UT WOS:000165418200001 ER PT J AU Su, WY AF Su, WY TI A new epsilon function for atmospheric correction algorithm SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ZONE COLOR SCANNER; IMAGERY; RADIANCES; SEAWIFS; OCEANS AB In this paper the atmospheric correction algorithms for two ocean color sensors, CZCS and SeaWiFS, were analyzed. Based upon the analysis, the 6S model was used to study the relationship between rho (us)(lambda) and rho (u)(lambda)+rho (ru)(lambda) and to develop a new epsilon function. The new epsilon (3)(lambda, 865) function considered the aerosol scattering effect and the interaction between aerosols and atmospheric molecules as a whole. Using the epsilon (3)(lambda, 865) instead of the original SeaWiFS defined epsilon(lambda, 865) could avoid the converting between rho (us)(lambda) and rho (u)(lambda)+rho (ru)(lambda) and help to simplify the atmospheric correction algorithm to a great extent. C1 Chinese Acad Sci, Inst Atmospher Phys, Beijing 100029, Peoples R China. RP Su, WY (reprint author), NASA, Langley Res Ctr, Mail Stop 420, Hampton, VA 23681 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 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2000 VL 27 IS 22 BP 3707 EP 3710 DI 10.1029/1999GL007005 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 375TW UT WOS:000165418200026 ER PT J AU Fahnestock, MA Scambos, TA Shuman, CA Arthern, RJ Winebrenner, DP Kwok, R AF Fahnestock, MA Scambos, TA Shuman, CA Arthern, RJ Winebrenner, DP Kwok, R TI Snow megadune fields on the East Antarctic Plateau: extreme atmosphere-ice interaction SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Large dune fields occupy more than 500,000 km(2) of the East Antarctic Plateau. The "megadunes", or long-wavelength surface ripples, have amplitudes of only a few meters, wavelengths of a few kilometers, and parallel crests which can extend one hundred kilometers. They occur in areas characterized by low accumulation, extensively recrystallized snow, and strong scattering of the microwave part of the spectrum. Dune crests are oriented perpendicular to the regional katabatic wind direction. Snow megadunes are unlikely to be formed by simple wind transport of snow particles. C1 Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. Univ Colorado, CIRES, Natl Snow & Ice Data Ctr, Boulder, CO 80309 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fahnestock, MA (reprint author), Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. RI Kwok, Ron/A-9762-2008; Scambos, Ted/B-1856-2009; Fahnestock, Mark/N-2678-2013 OI Kwok, Ron/0000-0003-4051-5896; NR 14 TC 56 Z9 58 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 15 PY 2000 VL 27 IS 22 BP 3719 EP 3722 DI 10.1029/1999GL011248 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 375TW UT WOS:000165418200029 ER PT J AU Lee, T Boulanger, JP Foo, A Fu, LL Giering, R AF Lee, T Boulanger, JP Foo, A Fu, LL Giering, R TI Data assimilation by an intermediate coupled ocean-atmosphere model: Application to the 1997-1998 El Nino SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID TROPICAL PACIFIC; DRAG COEFFICIENT; WIND STRESS; SEA-LEVEL; PREDICTION; DYNAMICS; SYSTEM; THERMODYNAMICS; INITIALIZATION; TEMPERATURE AB Sea surface temperature, sea level, and pseudo wind stress anomaly data from late 1996 to early 1998 are assimilated into an intermediate coupled model of the Tropical Pacific. Model data consistency is examined. Impact of the assimilation on forecast is evaluated. The ocean component of the coupled model consists of a shallow water model with two baroclinic modes, an Ekman shear layer, and a mixed layer temperature equation. The atmospheric model is a statistical one (based on dominant covariance of historical surface temperature and pseudo wind stress anomaly data). The adjoint method is used to fit the coupled model to 6 months of data by optimally adjusting the initial state and model parameters. A forecast is performed using the end state of an assimilation experiment as initial conditions and using parameters estimated during the assimilation period. Thus the model state during the assimilation and that during the forecast belong to the same model trajectory in different periods. Such an initialization procedure is useful in avoiding initial shock during forecast due to inconsistency of an initial state with the coupled model physics. As a result of optimal adjustments of initial state and parameters, the model is able to reproduce observed interannual variability of sea surface temperature and sea level reasonably well. The averaged residual model data misfits over various 6 month periods are 0.5 degreesC and 5 cm, respectively. The model has a limited skill in reproducing much of the off-equatorial wind anomalies. The residual model data misfit in pseudo wind stress anomaly is larger than 10 m(2) s(-2). Forecasts initialized from the assimilation product are overall more realistic than those simply initialized from wind-forced ocean states. Consistent improvement due to optimal initialization is found for sea surface temperature and sea level anomalies in the central-eastern Pacific and zonal pseudo wind stress anomaly in the central Pacific, both in terms of root-mean-squared deviation from and correlation with the data. The adjustments of parameters in addition to initial state in a coupled context is found to be important to improving the model data consistency during the assimilation and the forecast. In particular, the estimated drag and damping coefficients properly regulate the relative strength of forcing and damping of the ocean state so as to fit the three types of observations during the assimilation (initialization) period, which facilitates the development of a large-amplitude warming event during the forecast. The study demonstrates the utility of oceanic and atmospheric data to estimate initial state and model parameters in a coupled context, which is useful to the evaluation, improvement, and initialization of El Nino-Southern Oscillation forecast models. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Paris 06, CNRS, Lab Oceanog Dynam & Climatol, F-75252 Paris 05, France. RP Lee, T (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 31 TC 20 Z9 21 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD NOV 15 PY 2000 VL 105 IS C11 BP 26063 EP 26087 DI 10.1029/2000JC900118 PG 25 WC Oceanography SC Oceanography GA 374NU UT WOS:000165351900002 ER PT J AU Keen, TR Allen, SE AF Keen, TR Allen, SE TI The generation of internal waves on the continental shelf by Hurricane Andrew SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID NEAR-INERTIAL OSCILLATIONS; TEXAS-LOUISIANA SHELF; NORTH-WEST SHELF; TROPICAL CYCLONES; TRAPPED WAVES; MODEL; CANYON; CURRENTS; SIMULATION; FIELD AB Observed currents, temperature, and salinity from moored instruments on the Louisiana continental slope and shelf reveal multiple baroclinic oscillations during Hurricane Andrew in August 1992. These measurements are supplemented by numerical models in order to identify possible internal wave generation mechanisms. The Princeton Ocean Model is run with realistic topography, stratification, and wind forcing to extend the observations to Mississippi Canyon and other areas on the shelf. A two-layer isopycnal model is used with idealized topography and spatially uniform winds to isolate internal waves generated in and around the canyon. The combination of the observations and the results from the numerical models indicates several possible mechanisms for generating long internal waves: (1) near-inertial internal waves were generated across the slope and shelf by dislocation of the thermocline by the wind stress; (2) interaction of inertial flow with topography generated internal waves along the shelf break, which bifurcated into landward and seaward propagating phases; (3) downwelling along the coast depressed the thermocline; after downwelling relaxes, an internal wave front propagates as a Kelvin wave; and (4) Poincare waves generated within Mississippi Canyon propagate seaward while being advected westward over the continental slope. These processes interact to produce a three-dimensional internal wave field, which was only partly captured by the observations. C1 USN, Res Lab, Div Oceanog, Stennis Space Ctr, Stennis Space Ctr, MS 39529 USA. Univ British Columbia, Dept Earth & Ocean Sci, Vancouver, BC V6T 1Z4, Canada. RP Keen, TR (reprint author), USN, Res Lab, Div Oceanog, Stennis Space Ctr, Code 7322, Stennis Space Ctr, MS 39529 USA. NR 43 TC 14 Z9 14 U1 2 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD NOV 15 PY 2000 VL 105 IS C11 BP 26203 EP 26224 DI 10.1029/2000JC900137 PG 22 WC Oceanography SC Oceanography GA 374NU UT WOS:000165351900011 ER PT J AU Robinson, MB Li, D Rogers, JR Hyers, RW Savage, L Rathz, TJ AF Robinson, MB Li, D Rogers, JR Hyers, RW Savage, L Rathz, TJ TI High undercooling of Ni59Nb41 alloy in a containerless electrostatic levitation facility SO APPLIED PHYSICS LETTERS LA English DT Article ID SOLIDIFICATION; MELTS; SYSTEM; NI AB Utilizing the containerless electrostatic levitation facility at NASA/MSFC, we were able to undercool the Ni59Nb41 (atomic) alloy by 210 K which was 160 degrees farther than the results of previous flight experiments. Undercoolings were clustered around 200 K during the repeated melting-freezing cycles on a single sample. Prior to this work, a metastable liquid separation had been presumed to limit the undercooling of this alloy. However, microstructural observations have revealed that undercooling was limited by crystal nucleation. (C) 2000 American Institute of Physics. [S0003-6951(00)04346-1]. C1 NASA, George C Marshall Space Flight Ctr, Sci Directorate 47, Huntsville, AL 35812 USA. Univ Alabama, Huntsville, AL 35899 USA. RP Robinson, MB (reprint author), NASA, George C Marshall Space Flight Ctr, Sci Directorate 47, Huntsville, AL 35812 USA. RI Hyers, Robert/G-3755-2010 NR 15 TC 10 Z9 13 U1 2 U2 6 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD NOV 13 PY 2000 VL 77 IS 20 BP 3266 EP 3268 DI 10.1063/1.1326047 PG 3 WC Physics, Applied SC Physics GA 371FJ UT WOS:000165167600046 ER PT J AU Kogut, A Hinshaw, G AF Kogut, A Hinshaw, G TI Simulations of foreground effects for cosmic microwave background polarization SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; methods : data analysis ID GALACTIC EMISSION; SPINNING DUST AB We use a simple model to investigate the effect of polarized Galactic foreground emission on the ability of planned cosmic microwave background (CMB) missions to detect and model CMB polarization. Emission from likely polarized sources (synchrotron and spinning dust) would dominate the polarization of the microwave sky at frequencies below 90 GHz if known Galactic foregrounds are at least 10% polarized at high latitude (\b\ > 30 degrees). Maps of polarization at frequencies below 90 GHz will likely require correction for foreground emission to enable statistical analysis of the individual Stokes Q or U components. The temperature-polarization cross-correlation is less affected by foreground emission, even if the foreground polarization is highly correlated with the foreground intensity. Polarized foregrounds, even if uncorrected do not dominate the uncertainty in the temperature-polarization cross-correlation for instrument noise levels typical of the Microwave Anisotropy Probe (MAP) experiment. Methods that remove Galactic signals at the cost of signal-to-noise ratio should carefully balance the value of rejecting faint foregrounds with the cost of increased instrument noise. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Kogut, A (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Code 685, Greenbelt, MD 20771 USA. RI Kogut, Alan/D-6293-2012 NR 24 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP 530 EP 534 DI 10.1086/317161 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TD UT WOS:000165599300004 ER PT J AU Malhotra, S Hollenbach, D Helou, G Silbermann, N Valjavec, E Rubin, RH Dale, D Hunter, D Lu, N Lord, S Dinerstein, H Thronson, H AF Malhotra, S Hollenbach, D Helou, G Silbermann, N Valjavec, E Rubin, RH Dale, D Hunter, D Lu, N Lord, S Dinerstein, H Thronson, H TI Probing the interstellar medium in early-type galaxies with Infrared Space Observatory observations SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : elliptical and lenticular, cD; galaxies : ISM; infrared : ISM : continuum infrared : ISM : lines and bands; ISM : atoms; radiation mechanisms : thermal ID AMES ELLIPTIC GALAXIES; EXTENDED IONIZED-GAS; C-II LINE; MOLECULAR GAS; PHOTODISSOCIATION REGIONS; H-I; STAR-FORMATION; SPECTROSCOPIC PARAMETERS; ISOCAM OBSERVATIONS; MATTER AB Four IRAS-detected early-type galaxies were observed with the Infrared Space Observatory (ISO) With the exception of the 15 mum image of NGC 1052, the mid-IR images of NGC 1052, NGC 1155, NGC 5866, and NGC 6958 at 4.5, 7, and 15 pm show extended emission. Mid-IR emission from NGC 1052, NGC 1155, and NGC 6958 follows a de Vaucouleurs profile. The ratio of 15 mum/7 mum flux decreases with radius in these galaxies, approaching the values empirically observed for purely stellar systems. In NGC 5866, the 7 and 15 pm emission is concentrated in the edge-on dust lane. All the galaxies are detected in the CC nl (158 mum) line, and the SOs NGC 1155 and NGC 5866 are detected in the [O I] (63 mum) line as well. Previous detections of neutral interstellar medium (ISM) are sparse: only NGC 1052 had been detected in H I and NGC 5866 in CO. The ISO long-wavelength spectrograph observations of the CC nrl line are more sensitive measures of cool neutral ISM than H I and CO by about a factor of 10-100. Comparison of [C II] with H alpha shows that [C II] does not arise in H II regions and therefore must arise in the neutral medium. Three of four early-type galaxies, namely, NGC 1052, NGC 6958, and NGC 5866, have low ratios of far-infrared to blue luminosity and show a lower L-[C II]/L-FIR, which is explained by postulating a softer radiation field from old stellar populations in early-type galaxies, compared to spirals and irregulars, where young stars are present. While optical photons are effective in heating the dust, UV radiation is needed to heat the gas by the grain photoelectric mechanism. The low [C II]/CO ratio in NGC 5866 [L-[C II]/L-CO(1-0) less than or equal to 570] confirms this scenario. We estimate the UV radiation expected from the old stellar populations in these galaxies and compare it to that needed to heat the gas to account for the cooling observed [C II] and [O I] lines. In three out of four galaxies, NGC 1052, NGC 5866, and NGC 6958, the predicted UV radiation falls short by a factor of 2-3 of that required to sufficiently heat the gas. In view of the observed intrinsic scatter in the "UV upturn" in elliptical galaxies and its great sensitivity to age and metallicity effects, this difference is not significant. However, the much larger difference (about a factor of 20) between the UV radiation from old stars and that needed to produce the far-infrared lines for NGC 1155 is strong evidence for the presence of an additional UV source, probably young stars, in NGC 1155. C1 Kitt Peak Natl Observ, Tucson, AZ 85726 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. CALTECH, IPAC, Pasadena, CA 91125 USA. Lowell Observ, Flagstaff, AZ 86001 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. NASA Headquarters, Washington, DC 20546 USA. RP Malhotra, S (reprint author), Kitt Peak Natl Observ, POB 26732, Tucson, AZ 85726 USA. NR 66 TC 22 Z9 22 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP 634 EP 643 DI 10.1086/317119 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TD UT WOS:000165599300012 ER PT J AU Proga, D Stone, JM Kallman, TR AF Proga, D Stone, JM Kallman, TR TI Dynamics of line-driven disk winds in active galactic nuclei SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; galaxies : active; hydrodynamics; instabilities; methods : numerical ID BROAD-ABSORPTION-LINE; QUASI-STELLAR OBJECTS; X-RAY BINARIES; RADIATIVE ACCELERATION; ACCRETION DISKS; EMISSION-LINE; MODELS; QSOS; OUTFLOWS; PRESSURE AB We present the results of axisymmetric time-dependent hydrodynamic calculations of line-driven winds from accretion disks in active galactic nuclei (AGNs). We assume the disk is hat, Keplerian, geometrically thin, and optically thick, radiating according to the a-disk prescription. The central engine of the AGN is a source of both ionizing X-rays and wind-driving UV photons. To calculate the radiation force, we take into account radiation from the disk and the central engine. The gas temperature and ionization state in the wind are calculated self-consistently from the photoionization and heating rate of the central engine. We find that a disk accreting onto a 10(8) M. black hole at the rate of 1.8 M. yr(-1) can launch a wind at similar to 10(16) cm from the central engine. The X-rays from the central object are significantly attenuated by the disk atmosphere so they cannot prevent the local disk radiation from pushing matter away from the disk. However, in the supersonic portion of the flow high above the disk, the X-rays can overionize the gas and decrease the wind terminal velocity. For a reasonable X-ray opacity, e.g., kappa (X) = 40 g(-1) cm(2), the disk wind can be accelerated by the central UV radiation to velocities of up to 15,000 km s(-1) at a distance of similar to 10(17) cm from the central engine. The covering factor of the disk wind is similar to 0.2. The wind is unsteady and consists of an opaque, slow vertical flow near the disk that is bounded on the polar side by a high-velocity stream. A typical column density through the fast stream is a few times 10(23) cm(-2) so the stream is optically thin to the UV radiation. This low column density is precisely why gas can be accelerated to high velocities. The fast stream contributes nearly 100% to the total wind mass-loss rate of 0.5 M. yr(-1). C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Proga, D (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 50 TC 429 Z9 431 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP 686 EP 696 DI 10.1086/317154 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TD UT WOS:000165599300015 ER PT J AU Valinia, A Tatischeff, V Arnaud, K Ebisawa, K Ramaty, R AF Valinia, A Tatischeff, V Arnaud, K Ebisawa, K Ramaty, R TI On the origin of the iron K line in the spectrum of the galactic X-ray background SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; Galaxy : general; ISM : structure; supernova remnants; X-rays : ISM ID ENERGY COSMIC-RAYS; CONTINUUM EMISSION; SHELL IONIZATION; RIDGE; RADIATION; FORMULAS; ELEMENTS; ASCA AB We propose a mechanism for the origin of the Galactic ridge X-ray background that naturally explains the properties of the Fe K line, specifically the detection of the centroid line energy below 6.7 keV and the apparent broadness of the line. Motivated by recent evidence of nonthermal components in the spectrum of the Galactic X-ray/gamma -ray background, we consider a model that is a mixture of thermal plasma components of perhaps supernova origin and nonthermal emission from the interaction of low-energy cosmic-ray electrons (LECRe) with the interstellar medium. The LECRe may be accelerated in supernova explosions or by ambient interstellar plasma turbulence. Atomic collisions of fast electrons produce characteristic nonthermal, narrow X-ray emission lines that can explain the complex Galactic background spectrum. Using the ASCA GIS archival data from the Scutum arm region, we show that a two-temperature thermal plasma model with kT similar to 0.6 and similar to 2.8 keV, plus a LECRe component models the data satisfactorily. Our analysis rules out a purely nonthermal origin for the emission. It also rules out a significant contribution from low-energy cosmic-ray ions, because their nonthermal X-ray production would be accompanied by a nuclear gamma -ray line diffuse emission exceeding the upper limits obtained using OSSE, as well as by an excessive Galaxy-wide Be production rate. The proposed model naturally explains the observed complex line features and removes the difficulties associated with previous interpretations of the data which evoked a very hot thermal component (kT similar to 7 keV). C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. CNRS, IN2P3, Ctr Spectrometrie Nucl & Spectrometrie Masse, F-91405 Orsay, France. RP Valinia, A (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. EM valinia@milkyway.gsfc.nasa.gov NR 36 TC 91 Z9 91 U1 1 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP 733 EP 739 DI 10.1086/317133 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TD UT WOS:000165599300019 ER PT J AU Sahai, R Nyman, LA Wootten, A AF Sahai, R Nyman, LA Wootten, A TI He 2-113: A multipolar planetary nebula with rings around a cool Wolf-Rayet star SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; planetary nebulae : individual (He 2-113); radio lines : ISM; stars : AGB and post-AGB; stars : mass loss ID BIPOLAR PROTOPLANETARY NEBULA; WC CENTRAL STARS; MASS-LOSS RATES; CIRCUMSTELLAR ENVELOPES; CARBON STARS; RED GIANTS; AGB STARS; EMISSION; CPD-56-DEGREES-8032; EVOLUTION AB We present Her imaging and molecular-line (CO) observations of He 2-113, an object which belongs to a rare class of planetary nebulae with Wolf-Rayet type central stars. The Her images, obtained with the Hubble Space Telescope Wide-Field Planetary Camera 2, show that He 2-113 has an overall bipolar shape and two bright, knotty, compact ringlike structures around the central star. The major bipolar axis and the axis of symmetry of the rings are not colinear. A third, smaller, lobe is found to extend along an axis different from both of the above. The central star of He 2-113 is conspicuously offset from the geometrical centers of the rings and the main bipolar lobes. A faint extended round halo surrounds the bipolar nebula, probably representing the spherical mass-loss phase of the progenitor AGB red giant. The CO data indicate that this halo is mostly neutral and expanding at 28 km s(-1); an extended weak blue wing indicates that some of the molecular gas has been accelerated to significantly larger velocities. Self-consistent modeling of the CO data and IRAS far-infrared flux, including heating-cooling to calculate the gas kinetic temperature, shows that the mass-loss rate of the progenitor AGE star is relatively high (similar to 10(-4) M. yr(-1)) and that the molecular gas is relatively cold; the gas-to-dust ratio (by mass) is 190. The very aspherical morphology of the He 2-113 nebula may allow ionizing radiation to escape preferentially from the nebula along directions with relatively low optical depth. The observed nebular structure is not consistent with the generalized interacting winds model of planetary nebula formation. The multilobed structure supports a new model by Sahai & Trauger in which collimated outflows with changing directionality are: the primary agent for the shaping of planetary nebulae. The origin of the rings and the offset of the central star remain puzzling. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. ESO La Silla, Santiago 19, Chile. Onsala Space Observ, S-43992 Onsala, Sweden. NRAO, Charlottesville, VA 22903 USA. RP Sahai, R (reprint author), CALTECH, Jet Prop Lab, MS 183-900, Pasadena, CA 91109 USA. NR 45 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP 880 EP 888 DI 10.1086/317123 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TD UT WOS:000165599300032 ER PT J AU McConnell, ML Ryan, JM Collmar, W Schonfelder, V Steinle, H Strong, AW Bloemen, H Hermsen, W Kuiper, L Bennett, K Phlips, BF Ling, JC AF McConnell, ML Ryan, JM Collmar, W Schonfelder, V Steinle, H Strong, AW Bloemen, H Hermsen, W Kuiper, L Bennett, K Phlips, BF Ling, JC TI A high-sensitivity measurement of the MeV gamma-ray spectrum of Cygnus X-1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; black hole physics; gamma rays : observations; stars : individual (Cygnus X-1); X-rays : stars ID HARD X-RAY; BLACK-HOLE CANDIDATES; TRANSITION DISK MODEL; STOCHASTIC PARTICLE-ACCELERATION; COMPTONIZATION MODELS; THERMAL PLASMAS; MEV EMISSION; PAIR-EQUILIBRIUM; COMPACT OBJECTS; CORONA MODELS AB The Compton Gamma Ray Observatory (CGRO) has observed the Cygnus region on several occasions since its launch in 1991. The data collected by the COMPTEL experiment on CGRO represent the most sensitive observations to date of Cygnus X-1 in the 0.75-30 MeV range. A spectrum accumulated by COMPTEL over 10 weeks of observation time shows significant evidence for emission extending out to several MeV. We have combined these data with contemporaneous data from both BATSE and OSSE to produce a broadband gamma -ray spectrum, corresponding to the low X-ray state of Cygnus X-1, extending from 50 keV up to similar to5 MeV. Although there is no evidence for any broad-line-like emissions in the MeV region, these data further confirm the presence of a hard tail at energies above several hundred keV. In particular, the spectrum at MeV energies can be described as a power law with a photon spectral index of alpha = -3.2, with no evidence for a cutoff at high energies. For the 200 keV-5 MeV spectrum, we provide a quantitative description of the underlying electron spectrum, in the context of a hybrid thermal/nonthermal model for the emission. The electron spectrum can be described by a thermal Maxwellian with a temperature of kT(e) = 86 keV and a nonthermal power-law component with a spectral index of p(e) = 4.5. The spectral data presented here should provide a useful basis for further theoretical modeling. C1 Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA. Max Planck Inst Extraterr Phys, D-37075 Garching, Germany. SRON, Utrecht, Netherlands. Estec, Div Astrophys, Noordwijk, Netherlands. George Mason Univ, Fairfax, VA 22030 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP McConnell, ML (reprint author), Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA. EM Mark.McConnell@unh.edu; James.Ryan@unh.edu; wec@mpe.mpg.de; vos@mpe.mpg.de; hcs@mpe.mpg.de; aws@mpe.mpg.de; h.bloemen@sron.nl; w.hermsen@sron.nl; l.m.kuiper@sron.nl; kbennett@astro.estec.esa.nl; phlips@gamma.nrl.navy.mil; jling@jplsp.jpl.nasa.gov NR 80 TC 74 Z9 74 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 NOV 10 PY 2000 VL 543 IS 2 BP 928 EP 937 DI 10.1086/317128 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TD UT WOS:000165599300036 ER PT J AU Timmes, FX Zingale, M Olson, K Fryxell, B Ricker, P Calder, AC Dursi, LJ Tufo, H MacNeice, P Truran, JW Rosner, R AF Timmes, FX Zingale, M Olson, K Fryxell, B Ricker, P Calder, AC Dursi, LJ Tufo, H MacNeice, P Truran, JW Rosner, R TI On the cellular structure of carbon detonations SO ASTROPHYSICAL JOURNAL LA English DT Article DE hydrodynamics; instabilities; nuclear reactions, nucleosynthesis, abundances shock waves; supernovae : general ID IA SUPERNOVAE AB We present the results of a numerical study on two-dimensional carbon detonations. For an upstream density of 10(7) g cm(-3) the length-to-width ratio of the detonation cells is about 1.6 and is not strongly dependent on the spatial resolution of the simulation. However, the curvature of the weak incident shocks, strength of the triple points and transverse waves, and sizes of the underreacted and overreacted regions all depend strongly on the spatial resolution of the calculation. These resolution studies help define the minimum resolution required by multidimensional Type Ia supernovae models where the cellular structure of a detonation front is a kev feature of the model. C1 Univ Chicago, Ctr Astrophys Thermonucl Flashes, Chicago, IL 60637 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Timmes, FX (reprint author), Univ Chicago, Ctr Astrophys Thermonucl Flashes, 5640 S Ellis Ave, Chicago, IL 60637 USA. RI Calder, Alan/E-5348-2011; MacNeice, Peter/F-5587-2012; OI Zingale, Michael/0000-0001-8401-030X; Dursi, Jonathan/0000-0002-4697-798X NR 18 TC 24 Z9 25 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP 938 EP 954 DI 10.1086/317135 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TD UT WOS:000165599300037 ER PT J AU Brosius, JW Thomas, RJ Davila, JM Landi, E AF Brosius, JW Thomas, RJ Davila, JM Landi, E TI Analysis of a solar active region extreme-ultraviolet spectrum from SERTS-97 SO ASTROPHYSICAL JOURNAL LA English DT Article DE instrumentation : spectrographs; line : identification; Sun : activity; Sun : corona; Sun : UV ID OPTICALLY THIN PLASMAS; QUIET-SUN; EMISSION-LINES; DENSITY DIAGNOSTICS; ATOMIC DATABASE; IONIZATION EQUILIBRIUM; COORDINATED SERTS; SPECTROGRAPH; CHIANTI; WAVELENGTHS AB Goddard Space Flight Center's Solar EW Research Telescope and Spectrograph was flown on 1997 November 18, carrying an intensified CCD detector and a multilayer-coated toroidal diffraction grating Rith enhanced sensitivity over that of a standard gold-coated grating throughout the instrument's 299-353 Angstrom spectral bandpass. Spectra and spectroheliograms of NOAA Active Region 8108 (N21 degrees, E18 degrees) were obtained with a spectral resolution (instrumental FWHM) of 115 m Angstrom. Nearly 100 emission lines were observed in the spatially averaged active region spectrum. Spectra and spectroheliograms of quiet areas south of the region were also obtained An end-to-end radiometric calibration of the rocket instrument was carried out at the Rutherford-Appleton Laboratory in the same facility that was used to calibrate the Coronal Diagnostic Spectrometer experiment on SOHO and using the same EUV light source. The accuracy of this calibration is confirmed by the excellent agreement between the measured and theoretical values of density- and temperature-insensitive line intensity ratios. Nine emission lines of Fe xv are identified in our spectrum; however, large differences between wavelengths in the CHIANTI database and some of the measured solar wavelengths, as well as inconsistencies of various theoretical intensity ratios, suggest a need for improvement in the Fe xv atomic physics parameters and/or the presence of unidentified blending lines. Density-sensitive line intensity ratios of Fe XI lambda lambda 308.55/352.67, Fe XII lambda lambda 338.27/352.11, Fe XIII lambda 320.80/312.17, and Fe XV lambda lambda 321.78/327.03 yield logarithmic electron densities (in cm(-3)) of 9.92 +/- 0.28, 9.74 +/- 0.28, 9.52 +/- 0.30, and 9.62 +/- 0.26, respectively. Using the strongest emission line observed for each ionization stage of Fe from rr through XVI and Ni XVIII, we find that all of the measured nonthermal line widths yield velocities consistent with 35 km s(-1). The differential emission measure curve derived from the observed line intensities exhibits a relative minimum at log T similar to 5.7, a broad maximum centered around log T similar to 6.3, and a rapid decline for temperatures above log T similar to 6.6. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Max Planck Inst Aeron, D-37191 Katlenburg Lindau, Germany. RP Brosius, JW (reprint author), Raytheon ITSS, 4400 Forbes Blvd, Lanham, MD 20706 USA. RI Landi, Enrico/H-4493-2011 NR 49 TC 49 Z9 50 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP 1016 EP 1026 DI 10.1086/317153 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TD UT WOS:000165599300046 ER PT J AU Blanton, M Lin, H AF Blanton, M Lin, H TI The distribution of [O II] emission-line widths of Las Campanas Redshift Survey galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : fundamental parameters; galaxies : luminosity function, mass function; galaxies : statistics ID LUMINOSITY FUNCTION; EVOLUTION; FIELD; DENSITY AB We present a simple functional form for the joint distribution of R-band luminosity and [O II] lambda 3727 emission-line equivalent widths of galaxies and show that this form is a good fit to the galaxies in the Las Campanas Redshift Survey. We find a relationship between [O II] equivalent width W and R-band luminosity L-R of the approximate form (W) approximate to (10 Angstrom)(L-R/L-R,(*))(-1/2), where L-R,L-*. is the characteristic luminosity in the Schechter function. Because this joint distribution yields information about the relationship between stellar mass in a galaxy and its recent star formation rate, it can be useful for testing theories of galaxy formation. Furthermore, understanding this joint distribution locally will make it easier to interpret the evolution of [O II] emission-line widths to higher redshifts. C1 NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, Batavia, IL 60510 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. RP Blanton, M (reprint author), NASA, Fermi Natl Accelerator Lab, Fermilab Astrophys Ctr, POB 500, Batavia, IL 60510 USA. NR 22 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP L125 EP L128 DI 10.1086/317283 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TE UT WOS:000165599400008 ER PT J AU Burrows, DN Michael, E Hwang, U McCray, R Chevalier, RA Petre, R Garmire, GP Holt, SS Nousek, JA AF Burrows, DN Michael, E Hwang, U McCray, R Chevalier, RA Petre, R Garmire, GP Holt, SS Nousek, JA TI The X-ray remnant of SN 1987A SO ASTROPHYSICAL JOURNAL LA English DT Article DE supernovae : general; supernovae : individual (SN 1987A); supernova remnants; X-rays : general; X-rays : stars ID SPACE-TELESCOPE OBSERVATIONS; LARGE-MAGELLANIC-CLOUD; CIRCUMSTELLAR RING; LINE EMISSION; SN-1987A; SPECTROSCOPY; ABUNDANCES; IMPACT; RADIO AB We present high-resolution Chandra observations of the remnant of SN 1987A in the Large Magellanic Cloud. The high angular resolution of the Chandra X-Ray Observatory permits us to resolve the X-ray remnant. We find that the remnant is shell-like in morphology, with X-ray peaks associated with some of the optical hot spots seen in Hubble Space Telescope images. The X-ray light curve has deviated from the linear flux increase observed by ROSAT, with a 0.5-2.0 keV luminosity of 1.5 x 10(35) ergs s(-1) in 2000 January. We set an upper limit of 2.3 x 10(34) ergs s(-1) on the observed luminosity of any embedded central source (0.5-2 keV). We also present a high-resolution spectrum and show that the X-ray emission is thermal in origin and is dominated by highly ionized species of O, Ne, Mg, and Si. C1 Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. Univ Colorado, Joint Inst Lab Astrophys, Boulder, CO 80309 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. RP Burrows, DN (reprint author), Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. NR 27 TC 75 Z9 75 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP L149 EP L152 DI 10.1086/317271 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TE UT WOS:000165599400014 ER PT J AU Kotani, T Kawai, N Nagase, F Namiki, M Sakano, M Takeshima, T Ueda, Y Yamaoka, K Hjellming, RM AF Kotani, T Kawai, N Nagase, F Namiki, M Sakano, M Takeshima, T Ueda, Y Yamaoka, K Hjellming, RM TI ASCA observations of the jet source XTE J1748-288 SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : close; stars : activity; stars : individual (XTE J1748-288); X-rays : stars ID RAY AB XTE J1748-288 is a new X-ray transient with a one-sided radio jet. It was observed with ASCA on 1998 September 6 and 26, 100 days after the onset of the radio X-ray outburst. The spectra were modeled with an attenuated power-law model, and the absorbed 2-6 keV flux was 4.6(-0.8)(+1.0) x 10(-11) and 2.2(0.6)(+0.8) x 10(-12) ergs s(-1) cm(-2) on 1998 September 6 and 26, respectively. The light curve shows that the steady exponential decay, with an e-folding time of 14 days, lasted over 100 days and 4 orders of magnitude from the peak of the outburst. The celestial region including the source was observed with ASCA on 1993 October 1 and 1994 September 22, years before the discovery. During those periods, the flux was less than or similar to 10(-13) ergs s(-1) cm(-2), below the ASCA detection limit. The jet blob colliding with the environmental matter is probably not the X-ray source, although the emission mechanism is not determined. A possible detection of a K line from highly ionized iron is discussed. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RIKEN, Cosm Radiat Lab, Wako, Saitama 3510198, Japan. ISAS, High Energy Astrophys Div, Kanagawa 2298510, Japan. Kyoto Univ, Dept Phys, Kyoto 6068502, Japan. Natl Radio Astron Observ, Socorro, NM 87801 USA. RP Kotani, T (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 20 TC 16 Z9 16 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 10 PY 2000 VL 543 IS 2 BP L133 EP L136 DI 10.1086/317276 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 378TE UT WOS:000165599400010 ER PT J AU Yau, ST Petsev, DN Thomas, BR Vekilov, PG AF Yau, ST Petsev, DN Thomas, BR Vekilov, PG TI Molecular-level thermodynamic and kinetic parameters for the self-assembly of apoferritin molecules into crystals SO JOURNAL OF MOLECULAR BIOLOGY LA English DT Article DE ferritin; self-assembly; molecular resolution; interaction energy; solvent entropy ID ATOMIC-FORCE MICROSCOPY; TETRAGONAL LYSOZYME CRYSTALS; ELECTRON-MICROSCOPY; STEP DYNAMICS; PROTEIN CRYSTALLIZATION; SURFACE-MORPHOLOGY; GROWTH-MECHANISM; PHASE-BEHAVIOR; TAPPING MODE; 101 FACES AB The self-assembly of apoferritin molecules into crystals is a suitable model for protein crystallization and aggregation; these processes underlie several biological and biomedical phenomena, as well as for protein and virus self-assembly. We use the atomic force microscope in situ, during the crystallization of apoferritin to visualize and quantify at the molecular level the processes responsible for crystal growth. To evaluate the governing thermodynamic parameters, we image the configuration of the incorporation sites, "kinks", on the surface of a growing crystal. We show that the kinks are due to thermal fluctuations of the molecules at the crystal-solution interface. This allows evaluation of the free energy of the intermolecular bond phi = 3.0 k(B)T = 7.3 kJ/mol. The crystallization free energy, extracted from the protein solubility, is -42 kJ/mol. Published determinations of the second virial coefficient and the protein solubility between 0 and 40 degreesC revealed that the enthalpy of crystallization is close to zero. Analyses based on these three values suggest that the main component in the crystallization driving force is the entropy gain of the water molecules bound to the protein molecules in solution and released upon crystallization. Furthermore, monitoring the incorporation of individual molecules in to the kinks, we determine the characteristic frequency of attachment of individual molecules at one set of conditions. This allows a correlation between the mesoscopic kinetic coefficient for growth and the molecular-level thermodynamic and kinetic parameters determined here. We found that step growth velocity, scaled by the molecular size, equals the product of the kink density and attachment frequency, i.e. the latter pair are the molecular-level parameters for self-assembly of the molecules into crystals. (C) 2000 Academic Press. C1 Univ Alabama, Dept Chem, Huntsville, AL 35899 USA. Univ Space Res Assoc, George C Marshall Space Flight Ctr, Huntsville, AL 35875 USA. RP Vekilov, PG (reprint author), Univ Alabama, Dept Chem, Huntsville, AL 35899 USA. FU NHLBI NIH HHS [HL58038] NR 81 TC 86 Z9 87 U1 2 U2 18 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-2836 J9 J MOL BIOL JI J. Mol. Biol. PD NOV 10 PY 2000 VL 303 IS 5 BP 667 EP 678 DI 10.1006/jmbi.2000.4171 PG 12 WC Biochemistry & Molecular Biology SC Biochemistry & Molecular Biology GA 373QH UT WOS:000165299800003 PM 11061967 ER PT J AU Gindulyte, A Massa, L Banks, BA Rutledge, SK AF Gindulyte, A Massa, L Banks, BA Rutledge, SK TI Can hydrocarbon chains be disrupted by fast O(3P) atoms? SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID LOW-EARTH-ORBIT; MOLECULAR-ENERGIES; SPACECRAFT MATERIALS; ELECTRON CORRELATION; GAUSSIAN-1 THEORY; 2ND-ROW COMPOUNDS; MOLLER-PLESSET; AB-INITIO; OXYGEN; DENSITY AB O(3P) is a highly reactive species which may cause damage to materials on contact. In low Earth orbit (LEO), high-energy collisions (similar to4.5 eV) of O(3P) with spacecraft materials can lead to extensive degradation. In this study, we use ab initio molecular orbital calculations to investigate the possibility of chain breaking in polyethylene caused by a single O(3P) attack under LEO conditions, because the occurrence of such reactions could greatly accelerate the erosion. The smallest alkanes (n = 2, 3, 5, or 7) serve as models of polyethylene. For the case of ethane (n = 2), we explore the triplet potential energy surface of the following reaction: O(3P) + CH(3)-CH(3) --> O-CH(3) + CH(3). Analogous reactions, in which O(3P) attacks a central carbon atom, are studied for the higher alkanes. Results obtained using the Hartree-Fock method, density functional theory, and, in the simplest case (i.e,, ethane), second-order Moller Plesset perturbation theory, Gaussian theoretical models (G1, G2, and G2MP2), and complete basis set (CBS-QB3) approaches are reported. We conclude that conditions in LEO are conducive to chain breaking in polyethylene caused by a single O(3P) attack. C1 CUNY Hunter Coll, Dept Chem, New York, NY 10021 USA. CUNY, Grad Sch, New York, NY 10016 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Massa, L (reprint author), CUNY Hunter Coll, Dept Chem, 695 Park Ave, New York, NY 10021 USA. EM lmassa@hunter.cuny.edu NR 47 TC 28 Z9 29 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD NOV 9 PY 2000 VL 104 IS 44 BP 9976 EP 9982 DI 10.1021/jp001817h PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 375QA UT WOS:000165411700022 ER PT J AU Chaban, GM Jung, JO Gerber, RB AF Chaban, GM Jung, JO Gerber, RB TI Anharmonic vibrational spectroscopy of glycine: Testing of ab initio and empirical potentials SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID SELF-CONSISTENT-FIELD; ION-DIP SPECTROSCOPY; GASEOUS GLYCINE; WAVE-FUNCTIONS; FORCE-FIELD; ENERGY; STATES; CONFORMERS; SURFACES; CLUSTERS AB The second-order Moller-Plesset ab initio electronic structure method is used to compute points on the potential energy surface of glycine. Some 50 000 points are computed, covering the spectroscopically relevant regions, in the vicinity of the equilibrium structures of the three lowest-lying conformers of glycine. The vibrational states and spectroscopy are computed directly from the potential surface points using the correlation corrected vibrational self-consistent field (CC-VSCF) method, and the results are compared with experiment. Anharmonic effects and couplings between different vibrational modes that are included in the treatment are essential for satisfactory accuracy. The following are found: (1) The spectroscopic predictions from the ab initio potential are in very good accord with matrix experiments. (2) Theory agrees even more closely with spectroscopic data for glycine in He droplets, where environmental effects are much weaker than in the matrix. This suggests that errors in the ab initio potential are smaller than rare-gas matrix effects. (3) The accuracy of the ab initio potential is. by this spectroscopic test, much superior to that of OPLS-AA, a state-of-the-cut empirical potential. The relative failure of the empirical potential is due to its inability to describe: details of the hydrogen-bonded interactions, and is most critical in one of the glycine conformers where such interactions play an especially important role. C1 Hebrew Univ Jerusalem, Dept Phys Chem, IL-91904 Jerusalem, Israel. Hebrew Univ Jerusalem, Fritz Haber Res Ctr, IL-91904 Jerusalem, Israel. Univ Calif Irvine, Dept Chem, Irvine, CA 92697 USA. RP Chaban, GM (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. NR 24 TC 83 Z9 83 U1 1 U2 7 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD NOV 9 PY 2000 VL 104 IS 44 BP 10035 EP 10044 DI 10.1021/jp002297t PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 375QA UT WOS:000165411700030 ER PT J AU Suresh, A AF Suresh, A TI Positivity-preserving schemes in multidimensions SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE advection; positivity preserving; upwind ID EULER EQUATIONS; ADVECTION AB The performance of the MUSCL-Hancock upwind scheme is examined on problems of two-dimensional advection. It is found that when the advection direction is skewed relative to the mesh, most discrete total variation (TVD) limiters give rise to large spurious oscillations near discontinuities. The cause of these oscillations is traced to reconstructions that are not bounded by neighboring cell averages. It is proved that if the reconstruction in each cell is bounded by the cell averages of rst order neighbors, then the MUSCL-Hancock scheme is positivity preserving. A simple limiter that achieves such bounded reconstructions is presented next along with a variant that is uniformly second order accurate. Numerical experiments show that the new schemes are accurate and efficient and compare favorably with other schemes. C1 NASA, Dynacs Engn Inc, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Suresh, A (reprint author), NASA, Dynacs Engn Inc, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 18 TC 10 Z9 10 U1 0 U2 1 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD NOV 8 PY 2000 VL 22 IS 4 BP 1184 EP 1198 DI 10.1137/S1064827599360443 PG 15 WC Mathematics, Applied SC Mathematics GA 375BL UT WOS:000165379600003 ER PT J AU Beam, RM Warming, RF AF Beam, RM Warming, RF TI Multiresolution analysis and supercompact multiwavelets SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE wavelets; multiwavelets; multiresolution ID WAVELETS; BASES AB The Haar wavelets can represent exactly any piecewise constant function. The motivation for the present development is Alpert's family of compact orthogonal multiwavelets that can represent exactly any piecewise polynomial function. We choose to derive the algorithm in the style and notation of Harten's multiresolution analysis as extended to multiwavelets by the authors. We begin with a description of the nested grid hierarchy. Next comes the decomposition, which is the heart of the algorithm, and finally the reconstruction. The basis functions ( which are nonfractal) retain the spatial compactness of the Haar basis functions, which enhances the algorithm application to nonperiodic and piecewise continuous data. C1 NASA, Adv Computat Methods Branch, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Beam, RM (reprint author), NASA, Adv Computat Methods Branch, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 8 TC 10 Z9 10 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD NOV 8 PY 2000 VL 22 IS 4 BP 1238 EP 1268 DI 10.1137/S1064827596311906 PG 31 WC Mathematics, Applied SC Mathematics GA 375BL UT WOS:000165379600006 ER PT J AU Warming, RF Beam, RM AF Warming, RF Beam, RM TI Discrete multiresolution analysis using hermite interpolation: Biorthogonal multiwavelets SO SIAM JOURNAL ON SCIENTIFIC COMPUTING LA English DT Article DE wavelets; multiwavelets; multiresolution ID WAVELETS; SCHEME AB We generalize Harten's interpolatory multiresolution representation to include Hermite interpolation. Compact Hermite interpolation with optimal order accuracy is used in both the decomposition and reconstruction algorithm. The resulting multiple basis functions (biorthogonal multiwavelets) are symmetric or skew-symmetric, compact, and analytic. Harten's approach has several advantages: the multiresolution scheme is inherently discrete, nonperiodic boundary conditions are easy to implement, and the representation can be extended to nonuniform grids in bounded domains. We demonstrate the compression features of the new multiple basis functions by application to several examples. C1 NASA, Adv Computat Methods Branch, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Warming, RF (reprint author), NASA, Adv Computat Methods Branch, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 16 TC 13 Z9 13 U1 0 U2 0 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 1064-8275 J9 SIAM J SCI COMPUT JI SIAM J. Sci. Comput. PD NOV 8 PY 2000 VL 22 IS 4 BP 1269 EP 1317 DI 10.1137/S1064827597315236 PG 49 WC Mathematics, Applied SC Mathematics GA 375BL UT WOS:000165379600007 ER PT J AU Lissauer, JJ Marcy, GW Ida, S AF Lissauer, JJ Marcy, GW Ida, S TI Extrasolar planets SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article; Proceedings Paper CT 2nd Annual Japanese-American Frontiers of Science Symposium CY OCT 01-03, 1999 CL TSUKUBA, JAPAN ID CIRCUMSTELLAR DISKS; GIANT PLANETS; SYSTEMS; ACCRETION; DIVERSITY; COMPANION; JUPITER; ORIGIN; NEBULA; CORES AB The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However. these models require some modifications to explain the properties of the observed extrasolar planetary systems. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94709 USA. Tokyo Inst Technol, Dept Earth & Planetary Sci, Meguro Ku, Tokyo 152, Japan. RP Lissauer, JJ (reprint author), NASA, Ames Res Ctr, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. NR 22 TC 0 Z9 0 U1 0 U2 2 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD NOV 7 PY 2000 VL 97 IS 23 BP 12405 EP 12406 DI 10.1073/pnas.210381997 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 372GK UT WOS:000165225800009 PM 11035782 ER PT J AU Piro, L Garmire, G Garcia, M Stratta, G Costa, E Feroci, M Meszaros, P Vietri, M Bradt, H Frail, D Frontera, F Halpern, J Heise, J Hurley, K Kawai, N Kippen, RM Marshall, F Murakami, T Sokolov, VV Takeshima, T Yoshida, A AF Piro, L Garmire, G Garcia, M Stratta, G Costa, E Feroci, M Meszaros, P Vietri, M Bradt, H Frail, D Frontera, F Halpern, J Heise, J Hurley, K Kawai, N Kippen, RM Marshall, F Murakami, T Sokolov, VV Takeshima, T Yoshida, A TI Observation of X-ray lines from a gamma-ray burst (GRB991216): Evidence of moving ejecta from the progenitor SO SCIENCE LA English DT Article ID IRON LINE; AFTERGLOW; SPECTRA; EDGE AB We report on the discovery of two emission features observed in the x-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 December 1999 by the Chandra X-ray Observatory. These features are identified with the Ly(alpha), Line and the narrow recombination continuum by hydrogenic ions of iron at a redshift z = 1.00 +/- 0.02, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, a quantity of iron similar to0.01 of the mass of the sun at a velocity similar to0.1 of the speed of light, probably by a supernova explosion. C1 CNR, Ist Astrofis Spaziale, I-00133 Rome, Italy. Penn State Univ, Dept Astron & Astrophys, Davey Lab 525, University Pk, PA 16802 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Roma Tre, Dept Phys, I-00146 Rome, Italy. MIT, Cambridge, MA 02139 USA. Natl Radio Astron Observ, Socorro, NM 87801 USA. CNR, Ist Tecnol & Studio Radiaz Extraterr, I-40129 Bologna, Italy. Columbia Univ, Dept Astrophys, New York, NY 10027 USA. SRON, NL-3584 CA Utrecht, Netherlands. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. RIKEN, Inst Phys & Chem Res, Wako, Saitama 3510198, Japan. Univ Alabama, NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35899 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. Russian Acad Sci, Special Astrophys Observ, Nizhnii Arkhyz 369167, Karachaevo Cher, Russia. NASDA, Natl Space Dev Agcy Japan, Minato Ku, Tokyo 10560, Japan. RP Piro, L (reprint author), CNR, Ist Astrofis Spaziale, Via Fosso del Cavaliere, I-00133 Rome, Italy. RI PIRO, LUIGI/E-4954-2013; Stratta, Maria Giuliana/L-3045-2016; OI PIRO, LUIGI/0000-0003-4159-3984; Stratta, Maria Giuliana/0000-0003-1055-7980; Costa, Enrico/0000-0003-4925-8523; Feroci, Marco/0000-0002-7617-3421 NR 33 TC 242 Z9 245 U1 0 U2 3 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD NOV 3 PY 2000 VL 290 IS 5493 BP 955 EP 958 DI 10.1126/science.290.5493.955 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 370BV UT WOS:000165103200040 PM 11062121 ER PT J AU Hwang, SM Ryu, SO DeWitt, KJ Rabinowitz, MJ AF Hwang, SM Ryu, SO DeWitt, KJ Rabinowitz, MJ TI Reply to the comment on "Rate coefficient measurements of the reaction CH3+O-2=CH3O+O" SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID CHEMICAL-KINETICS C1 NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. Univ Toledo, Dept Chem Engn, Toledo, OH 43606 USA. RP Rabinowitz, MJ (reprint author), NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. NR 33 TC 3 Z9 3 U1 1 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1089-5639 J9 J PHYS CHEM A JI J. Phys. Chem. A PD NOV 2 PY 2000 VL 104 IS 43 BP 9803 EP 9805 DI 10.1021/jp994496m PG 3 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 371UN UT WOS:000165197800021 ER PT J AU Ryerson, CC Koenig, GG Reehorst, AL Pace, DJ AF Ryerson, CC Koenig, GG Reehorst, AL Pace, DJ TI Advancing icing detection SO AEROSPACE ENGINEERING LA English DT Article C1 USA, Cold Reg Res & Engn Lab, Hanover, NH 03755 USA. NASA, Glenn Res Ctr, Washington, DC USA. RP Ryerson, CC (reprint author), USA, Cold Reg Res & Engn Lab, Hanover, NH 03755 USA. NR 0 TC 1 Z9 2 U1 0 U2 0 PU SOC AUTOMOTIVE ENG INC PI WARRENDALE PA 400 COMMONWEALTH DRIVE, WARRENDALE, PA 15096 USA SN 0736-2536 J9 AEROSPACE ENG JI Aerosp. Eng. PD NOV PY 2000 VL 20 IS 11 BP 22 EP 24 PG 3 WC Engineering, Aerospace SC Engineering GA 375BP UT WOS:000165379900029 ER PT J AU Tsynkov, S Abarbanel, S Nordstrom, J Ryaben'kii, V Vatsa, V AF Tsynkov, S Abarbanel, S Nordstrom, J Ryaben'kii, V Vatsa, V TI Global artificial boundary conditions for computation of external flows with jets SO AIAA JOURNAL LA English DT Article ID NAVIER-STOKES EQUATIONS; NUMERICAL-SOLUTION AB We propose new global artificial boundary conditions (ABCs) for computation of flows with propulsive jets. The algorithm is based on application of the difference potentials method (DPM). Previously, similar boundary conditions have been implemented for calculation of external compressible viscous hows around finite bodies. The proposed modification substantially extends the applicability range of the DPM-based algorithm. We present the general formulation of the problem, describe our numerical methodology, and discuss the corresponding computational results. The particular configuration that we analyze is a slender three-dimensional body with boat-tail geometry and supersonic jet exhaust in a subsonic external flow under zero angle of attack. Similar to the results obtained earlier for the hows around airfoils and wings, current results for the jet flow case corroborate the superiority of the DPM-based ABCs over standard local methodologies from the standpoints of accuracy, overall numerical performance, and robustness. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Tsynkov, S (reprint author), Tel Aviv Univ, Inst Comp Applicat Sci & Engn, IL-69978 Tel Aviv, Israel. OI Nordstrom, Jan/0000-0002-7972-6183 NR 41 TC 5 Z9 6 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD NOV PY 2000 VL 38 IS 11 BP 2014 EP 2022 DI 10.2514/2.888 PG 9 WC Engineering, Aerospace SC Engineering GA 370RQ UT WOS:000165136400003 ER PT J AU Freund, JB Lele, SK Moin, P AF Freund, JB Lele, SK Moin, P TI Numerical simulation of a Mach 1.92 turbulent jet and its sound field SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA/CEAS 4th Aeroacoustics Conference CY JUN 02-04, 1998 CL TOULOUSE, FRANCE SP AIAA, CEAS ID AXISYMMETRIC JETS; INSTABILITY AB A perfectly expanded turbulent Mach 1.92 jet is simulated by direct numerical solution of the compressible Navier-Stokes equations in a computational domain that includes the near acoustic field. In place of a nozzle, turbulent inflow data were generated in a separate streamwise periodic jet simulation. Reynolds stresses, two-point correlations, and turbulent energy spectra are computed and discussed. The sound field is highly directional and dominated by Mach waves as are commonly observed experimentally. Analysis of the sound using weak-shock theory shows that nonlinear effects are significant away from the jet but that linear theory is sufficient to estimate near-field sound pressure levels. Although no attempt was made to match any particular experiment in detail, sound pressure levels are compared with experimental data at similar how conditions and are found to agree in general with jets at similar convective Mach numbers. C1 Univ Calif Los Angeles, Los Angeles, CA 90095 USA. Stanford Univ, Dept Aeronaut & Astronaut, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Freund, JB (reprint author), Univ Calif Los Angeles, Los Angeles, CA 90095 USA. RI Freund, Jonathan/A-6409-2014 NR 26 TC 67 Z9 75 U1 1 U2 6 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD NOV PY 2000 VL 38 IS 11 BP 2023 EP 2031 DI 10.2514/2.889 PG 9 WC Engineering, Aerospace SC Engineering GA 370RQ UT WOS:000165136400004 ER PT J AU Mehta, SK Bell-Robinson, DM Groves, TO Stetzenbach, LD Pierson, DL AF Mehta, SK Bell-Robinson, DM Groves, TO Stetzenbach, LD Pierson, DL TI Evaluation of portable air samplers for monitoring airborne culturable bacteria SO AIHAJ LA English DT Article DE airborne bacteria; bioaerosols; monitoring ID AEROSOLS AB Airborne culturable bacteria were monitored at five locations (three in an office/laboratory building and two in a private residence) in a series of experiments designed to compare the efficiency of four air samplers: the Andersen two-stage, Burkard portable, RCS Plus, and SAS Super 90 samplers. A total of 280 samples was collected. The four samplers were operated simultaneously, each sampling 100 L of air with collection on trypticase soy agar. The data were corrected by applying positive hole conversion factors for the Burkard portable, Andersen two-stage, and SAS Super 90 air samplers, and were expressed as log(10) values prior to statistical analysis by analysis of variance. The Burkard portable air sampler retrieved the highest number of airborne culturable bacteria at four of the five sampling sites, followed by the SAS Super 90 and the Andersen two-stage impactor. The number of bacteria retrieved by the RCS Plus was significantly less than those retrieved by the other samplers. Among the predominant bacterial genera retrieved by all samplers were Staphylococcus, Bacillus, Corynebacterium, Micrococcus, and Streptococcus. C1 NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Univ Nevada, Harry Reid Ctr Environm Studies, Las Vegas, NV 89154 USA. Enterprise Advisory Serv Inc, Houston, TX 77058 USA. RP Pierson, DL (reprint author), NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Mail Code SD3, Houston, TX 77058 USA. NR 14 TC 22 Z9 23 U1 1 U2 7 PU AMER INDUSTRIAL HYGIENE ASSOC PI FAIRFAX PA 2700 PROSPERITY AVE #250, FAIRFAX, VA 22031-4307 USA SN 1529-8663 J9 AIHAJ JI AIHAJ PD NOV-DEC PY 2000 VL 61 IS 6 BP 850 EP 854 DI 10.1202/0002-8894(2000)061<0850:EOPASF>2.0.CO;2 PG 5 WC Environmental Sciences; Public, Environmental & Occupational Health SC Environmental Sciences & Ecology; Public, Environmental & Occupational Health GA 390FX UT WOS:000166286000011 PM 11192219 ER PT J AU Dawson, DL Cutler, BS Hiatt, WR Hobson, RW Martin, JD Bortey, EB Forbes, WP Strandness, DE AF Dawson, DL Cutler, BS Hiatt, WR Hobson, RW Martin, JD Bortey, EB Forbes, WP Strandness, DE TI A comparison of cilostazol and pentoxifylline for treating intermittent claudication SO AMERICAN JOURNAL OF MEDICINE LA English DT Article ID DOUBLE-BLIND TRIAL; ARTERIAL-DISEASE; DRUG-TREATMENT; METAANALYSIS; MULTICENTER; MANAGEMENT AB PURPOSE: We performed a randomized, double-blind, placebo-controlled, multicenter trial to evaluate the relative efficacy and safety of cilostazol and pentoxifylline. PATIENTS AND METHODS: We enrolled patients with moderate-to-severe claudication from 54 outpatient vascular clinics, including sites at Air Force, Veterans Affairs, tertiary care, and university medical centers in the United States. Of 922 consenting patients, 698 met the inclusion criteria and were randomly assigned to blinded treatment with either cilostazol (100 mg orally twice a day), pentoxifylline (400 mg orally 3 times a day), or placebo. We measured maximal walking distance with constant-speed, variable-grade treadmill testing at baseline and at 4, 8, 12, 16, 20, and 24 weeks. RESULTS: Mean maximal walking distance of cilostazol-treated patients (n = 227) was significantly greater at every postbaseline visit compared with patients who received pentoxifylline (n = 232) or placebo (n = 239). After 24 weeks of treatment, mean maximal walking distance increased by a mean of 107 m (a mean percent increase of 54% from baseline) in the cilostazol group, significantly more than the 64-m improvement (a 30% mean percent increase) with pentoxifylline (P <0.001). The improvement with pentoxifylline was similar (P = 0.82) to that in the placebo group (65 m, a 34% mean percent increase). Deaths and serious adverse event rates were similar in each group. Side effects (including headache, palpitations, and diarrhea) were more common in the cilostazol-treated patients, but withdrawal rates were similar in the cilostazol (16%) and pentoxifylline (19%) groups. CONCLUSION: Cilostazol was significantly better than pentoxifylline or placebo for increasing walking distances in patients with intermittent claudication, but was associated with a greater frequency of minor side effects. Pentoxifylline and placebo had similar effects. Am J Med. 2000;109:523-530. (C) 2000 by Excerpta Medica, Inc. C1 Wilford Hall USAF Med Ctr, Lackland AFB, TX 78236 USA. Univ Massachusetts, Worcester, MA 01605 USA. Univ Colorado, Hlth Sci Ctr, Denver, CO USA. Univ Med & Dent New Jersey, New Jersey Med Sch, Newark, NJ 07103 USA. Otsuka Amer Pharmaceut Inc, Rockville, MD USA. Univ Washington, Seattle, WA 98195 USA. RP Dawson, DL (reprint author), NASA, Div Med Sci, Lyndon B Johnson Space Ctr, Mail Code SD,2101 NASA Rd 1, Houston, TX 77058 USA. NR 22 TC 204 Z9 215 U1 0 U2 4 PU EXCERPTA MEDICA INC PI NEW YORK PA 650 AVENUE OF THE AMERICAS, NEW YORK, NY 10011 USA SN 0002-9343 J9 AM J MED JI Am. J. Med. PD NOV PY 2000 VL 109 IS 7 BP 523 EP 530 DI 10.1016/S0002-9343(00)00569-6 PG 8 WC Medicine, General & Internal SC General & Internal Medicine GA 370HP UT WOS:000165117700001 PM 11063952 ER PT J AU Borisov, A Palme, H AF Borisov, A Palme, H TI Solubilities of noble metals in Fe-containing silicate melts as derived from experiments in Fe-free systems SO AMERICAN MINERALOGIST LA English DT Article ID PLATINUM-GROUP ELEMENTS; SIDEROPHILE ELEMENTS; OXYGEN FUGACITY; CORE FORMATION; GORGONA-ISLAND; PD; SULFIDE; MANTLE; RU; TEMPERATURE AB The solubilities of noble metals (NM: Ir, Pd, Au, Pt, and Ru) in FeO-free silicate melts are known from recent experimental work. In this paper, calculations are presented that relate solubilities of NM in FeO-free melts to those in FeO-containing melts. The main difference between these two systems is the formation of Fe-NM alloys in FeO-containing melts. At f(O2) conditions of the QFM buffer and 1200 degreesC, binary alloys of Fe with Au, Ru, Ir, Pd, or Pt containing 1, 2, 10, 17, and 25 at% Fe, respectively, are in thermodynamic equilibrium with a silicate melt with 10 mol% FeO. Thus alloy formation leads to a significant reduction in the solubility of Pt and to a lesser reduction in the solubility of Pd. The effects for Ir and Ru are small, and for Au almost negligible. The reduction in solubilities depends on temperature, oxygen fugacity, and FeO content of the silicate melt. Formation of FePt-alloys would lead to a preferred depletion of Pt in partial melts from the Earth's mantle, which, however, is not observed. One explanation is that mantle melting occurs under very oxidizing conditions (QFM+2). The calculations presented here should be considered a first step toward gaining a better understanding of the behavior of NM during igneous processes. C1 NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch, Houston, TX 77058 USA. Univ Cologne, Inst Mineral & Geochem, D-50674 Cologne, Germany. RP Borisov, A (reprint author), Russian Acad Sci, Inst Geol Ore Deposits Petrog Mineral & Geochem, Staromonetnyj 35, Moscow 109017, Russia. NR 52 TC 84 Z9 91 U1 3 U2 17 PU MINERALOGICAL SOC AMER PI WASHINGTON PA 1015 EIGHTEENTH ST, NW SUITE 601, WASHINGTON, DC 20036 USA SN 0003-004X J9 AM MINERAL JI Am. Miner. PD NOV-DEC PY 2000 VL 85 IS 11-12 BP 1665 EP 1673 PG 9 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 372EF UT WOS:000165220800009 ER PT J AU Wernet, MP Subramanian, A Mu, H Kadambi, JR AF Wernet, MP Subramanian, A Mu, H Kadambi, JR TI Comparison of particle image velocimetry and laser Doppler anemometry measurements in turbulent fluid flow SO ANNALS OF BIOMEDICAL ENGINEERING LA English DT Letter C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Case Western Reserve Univ, Dept Mech & Aerosp Engn, Cleveland, OH 44106 USA. RP Wernet, MP (reprint author), NASA, Glenn Res Ctr, MS 77-1,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 9 TC 5 Z9 5 U1 0 U2 3 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0090-6964 J9 ANN BIOMED ENG JI Ann. Biomed. Eng. PD NOV-DEC PY 2000 VL 28 IS 11 BP 1393 EP 1394 DI 10.1114/1.1336827 PG 2 WC Engineering, Biomedical SC Engineering GA 393WK UT WOS:000166492500011 PM 11212957 ER PT J AU Zhang, P Abraham, VS Kraft, KRK Rabchevsky, AG Scheff, SW Swain, JA AF Zhang, P Abraham, VS Kraft, KRK Rabchevsky, AG Scheff, SW Swain, JA TI Hyperthermic preconditioning protects against spinal cord ischemic injury SO ANNALS OF THORACIC SURGERY LA English DT Article ID HEAT-SHOCK; TRANSIENT ISCHEMIA; RAT; CHAPERONES; PARAPLEGIA; INDUCTION; NEURONS; BRAIN; MODEL AB Background. Paraplegia can result from operations requiring transient occlusion of the descending thoracic aorta. The present study tested whether inducing hyperthermia in rats before aortic ischemia would be neuroprotective. Methods. Rats were randomly assigned to hyperthermic preconditioning (n = 27) or control (n = 32) groups. Eighteen hours before ischemia, the hyperthermic preconditioned rats were heated at 41 degreesC for 15 minutes. Ten minutes of spinal ischemia were produced by balloon occlusion of the thoracic aorta. Neurologic performance scores were evaluated daily to 7 days after ischemia. The lumbar region of the spinal cord was removed for histologic grading. Results. The hyperthermic preconditioned animals had less permanent spinal cord injury compared with controls (29.6% versus 59.4%, p = 0.02), and the incidence of immediate paraplegia in the hyperthermic preconditioned group was significantly less than that in the control group (3.7% versus 28.1%, p = 0.03). Histologic scores correlated with the neurologic outcome at the time of sacrifice in rats with permanent spinal cord injury but not in those walking normally. Conclusions. We used a rat model of spinal cord ischemia and found that hyperthermic preconditioning before spinal cord ischemia resulted in improved clinical outcome. (Ann Thorac Surg 2000;70:1490-5) (C) 2000 by The Society of Thoracic Surgeons. C1 Univ Kentucky, Coll Med, Sanders Brown Ctr Aging, Lexington, KY 40536 USA. Univ Kentucky, Coll Med, Gill Heart Inst, Lexington, KY 40536 USA. RP Swain, JA (reprint author), NASA, Headquarters, Code U,300 E St SW, Washington, DC 20536 USA. NR 20 TC 22 Z9 26 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0003-4975 J9 ANN THORAC SURG JI Ann. Thorac. Surg. PD NOV PY 2000 VL 70 IS 5 BP 1490 EP 1495 DI 10.1016/S0003-4975(00)01851-8 PG 6 WC Cardiac & Cardiovascular Systems; Respiratory System; Surgery SC Cardiovascular System & Cardiology; Respiratory System; Surgery GA 372LP UT WOS:000165235400012 PM 11093475 ER PT J AU Cullings, KW Vogler, DR Parker, VT Finley, SK AF Cullings, KW Vogler, DR Parker, VT Finley, SK TI Ectomycorrhizal specificity patterns in a mixed Pinus contorta and Picea engelmannii forest in Yellowstone National Park SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Article ID DOUGLAS-FIR; MYCORRHIZAL INFECTION; PSEUDOTSUGA-MENZIESII; HOST-SPECIFICITY; FUNGI; BIOLOGY; ASSOCIATIONS; RESISTANCE; RHIZOPOGON; DIVERSITY AB We used molecular genetic methods to test two hypotheses, (i) that host plant specificity among ectomycorrhizal fungi would be common in a closed-canopy, mixed Pinus contorta-Picea engelmannii forest in Yellowstone National Park and (ii) that specificity would be more common in the early successional tree species, P. contorta, than in the invader, P. engelmannii, We identified 28 ectomycorrhizal fungal species collected from 27 soil cores. The proportion of P. engelmannii to P. contorta ectomycorrhizae was nearly equal (52 and 48%, respectively). Of the 28 fungal species, 18 composed greater than 95% of the fungal community. No species was associated exclusively with P. contorta, but four species, each found in only one core, and one species found in two cores were associated exclusively with P. engelmannii. These fungi composed less than 5% of the total ectomycorrhizae, Thus, neither hypothesis was supported, and hypothesized benefits of ectomycorrhizal specificity to both trees and fungi probably do not exist in this system. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Inst Forest Genet, Davis, CA 95616 USA. San Francisco State Univ, Dept Biol, San Francisco, CA 94132 USA. RP Cullings, KW (reprint author), NASA, Ames Res Ctr, MS 239-4, Moffett Field, CA 94035 USA. NR 39 TC 55 Z9 58 U1 2 U2 15 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1752 N ST NW, WASHINGTON, DC 20036-2904 USA SN 0099-2240 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD NOV PY 2000 VL 66 IS 11 BP 4988 EP + DI 10.1128/AEM.66.11.4988-4991.2000 PG 5 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA 369FM UT WOS:000165055300055 PM 11055953 ER PT J AU Kawabata, K Sato, M Travis, LD AF Kawabata, K Sato, M Travis, LD TI A new approach to computing theoretical polarization curves along the low latitude regions of a planetary disk observed at small phase angles SO APPLIED MATHEMATICS AND COMPUTATION LA English DT Article DE multiple scattering; radiative transfer; linear polarization; planetary atmospheres; light scattering; reflection matrix; Stokes parameters ID LIGHT-SCATTERING; MULTIPLE-SCATTERING; ATMOSPHERES; VENUS AB Linear polarization distributions computed along and around the intensity equator of a planetary disk observed at small phase angles tend to show a very pronounced artificial oscillatory behavior or wiggles. The purpose of this work is twofold: to direct attention to this rather tenacious, but not duly publicized computational problem on one hand, and to exploit some effective procedure to minimize those wiggles on the other. For these purposes, we have made extensive numerical computations of the linear polarization curves with various procedures at wavelength 365 nm employing the Venus cloud model of Hansen and Hovenier as a sample, some of which are presented in this work. Our results indicate that the use of the [0,1] part of the Gauss-Legendre quadrature points for mu, the cosine of the zenith angle of incident or emergent light, and their corresponding weights generated in the interval [-1, 1] works extremely well for interpolating reflection matrix elements. Furthermore, it is shown that sufficiently well-behaved polarization distribution curves can be obtained by computing the single scattering contributions to the reflection matrix elements exactly and those due to multiple scattering approximately using a natural bicubic spline interpolation formula where the independent variable is to be switched from mu to root1 - mu (2) if mu greater than or equal to 0.70 (7) over bar1 and vice versa. (C) 2000 Elsevier Science Inc. All rights reserved. C1 Sci Univ Tokyo, Dept Phys, Shinjuku Ku, Tokyo 1628601, Japan. NASA, Goddard Inst Space Studies, SSAI, New York, NY 10025 USA. RP Kawabata, K (reprint author), Sci Univ Tokyo, Dept Phys, Shinjuku Ku, 1-3 Kagurazaka, Tokyo 1628601, Japan. NR 24 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0096-3003 J9 APPL MATH COMPUT JI Appl. Math. Comput. PD NOV PY 2000 VL 116 IS 1-2 BP 115 EP 132 DI 10.1016/S0096-3003(99)00199-X PG 18 WC Mathematics, Applied SC Mathematics GA 367KC UT WOS:000090059400011 ER PT J AU Lacis, AA Carlson, BE Hansen, JE AF Lacis, AA Carlson, BE Hansen, JE TI Retrieval of atmospheric NO2, O-3, aerosol optical depth, effective radius and variance information from SAGE II multi-spectral extinction measurements SO APPLIED MATHEMATICS AND COMPUTATION LA English DT Article DE remote sensing; SAGE II; spectral retrieval; aerosols; aerosol size ID ABSORPTION CROSS-SECTIONS; STRATOSPHERIC AEROSOL; INVERSION ALGORITHM; REGION; NM AB The direct-beam spectral extinction of solar radiation contains information on atmospheric composition in a form that is essentially free from the data analysis complexities that often arise from multiple scattering. Ground based Multi-Filter Shadowband Radiometer (MFRSR) measurements provide such information for the vertical atmospheric column path, while solar occultation measurements from a satellite platform provide horizontal slices through the atmosphere. We describe application of a Multi-Spectral Atmospheric Column Extinction (MACE) analysis technique that we developed to analyze MFRSR data to occultation measurements made by Stratospheric Aerosol and Gas Experiment (SAGE II). For analysis, we select the 1985 Nevado del Ruiz volcanic eruption period to retrieve atmospheric profiles of ozone and NO2, and changes in the stratospheric aerosol size and optical depth. The time evolution of volcanic aerosol serves as a passive tracer to study stratospheric dynamics, and changes in particle size put constraints on the sulfur chemistry modeling of volcanic aerosols, (C) 2000 Published by Elsevier Science Inc. All rights reserved. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Lacis, AA (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Lacis, Andrew/D-4658-2012; Carlson, Barbara/D-8319-2012 NR 23 TC 4 Z9 4 U1 1 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0096-3003 J9 APPL MATH COMPUT JI Appl. Math. Comput. PD NOV PY 2000 VL 116 IS 1-2 BP 133 EP 151 DI 10.1016/S0096-3003(99)00200-3 PG 19 WC Mathematics, Applied SC Mathematics GA 367KC UT WOS:000090059400012 ER PT J AU Alexandrov, MD Lacis, AA AF Alexandrov, MD Lacis, AA TI A new three-parameter cloud/aerosol particle size distribution based on the generalized inverse Gaussian density function SO APPLIED MATHEMATICS AND COMPUTATION LA English DT Article DE size distribution; generalized inverse Gaussian distribution; Mie scattering parameters ID ATMOSPHERES; SCATTERING AB We describe a three-parameter cloud/aerosol size distribution based on the generalized inverse Gaussian density function that provides a simple and convenient recipe for characterizing aerosol radiative properties. The feature that makes this distribution attractive is that all of its moments can be calculated analytically providing simple formulas for the effective radius and variance and relating these to other important quantities such as the particle number and mass densities. Another advantage of this distribution is the smooth exponential cut-off not only for large particles sizes but also in small particles regime which prevents the singularity that occurs at zero size for large effective variances for distributions like the popular gamma distribution. Unlike most size distributions in current use the proposed Functional form has a third-parameter (order) which Provides greater flexibility in representing different distributional shapes. Analytical expressions for the moments of the generalized inverse Gaussian distribution in the generic case contain ratios of modified Bessel functions, however for half-integer orders these expressions are simple ratios of polynomials. As a practical example we compare extinction efficiency factors acid asymmetry parameters computed for several different orders of the proposed distribution function. (C) 2000 Published by Elsevier Science Inc. All rights reserved. C1 Columbia Univ, New York, NY 10025 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Alexandrov, MD (reprint author), Columbia Univ, 2880 Broadway, New York, NY 10025 USA. RI Lacis, Andrew/D-4658-2012 NR 8 TC 13 Z9 13 U1 2 U2 3 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0096-3003 J9 APPL MATH COMPUT JI Appl. Math. Comput. PD NOV PY 2000 VL 116 IS 1-2 BP 153 EP 165 DI 10.1016/S0096-3003(99)00201-5 PG 13 WC Mathematics, Applied SC Mathematics GA 367KC UT WOS:000090059400013 ER PT J AU Mishchenko, MI Lacis, AA AF Mishchenko, MI Lacis, AA TI Manifestations of morphology-dependent resonances in Mie scattering matrices SO APPLIED MATHEMATICS AND COMPUTATION LA English DT Article DE scattering; electromagnetics; Lorenz-Mie theory; scattering resonances; particle characterization ID ABSORBING SPHERES; LIGHT-SCATTERING AB Lorenz-Mic computations of the extinction cross-section for monodisperse spheres show the existence of a very complex structure that includes extremely narrow peaks called morphology-dependent resonances (MDRs). The width and magnitude of the peaks are highly sensitive functions of the size parameter and the refractive index of the sphere. So far the MDRs have been calculated and observed mostly for the total optical cross-sections and the scattered intensity, though it has been clear that they should also exist in the scattering matrix elements. In this paper we use modern visualization techniques to study the manifestations of MDRs in the elements of the Stokes scattering matrix and their dependence on the refractive index. We show that within MDRs, the scattering matrix elements may drastically change not only their magnitude, but also their sign. Even weak absorption inside the particles strongly modifies and then completely destroys the polarization resonance effects. (C) 2000 Published by Elsevier Science Inc. All rights reserved. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Mishchenko, MI (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM crimim@giss.nasa.gov RI Lacis, Andrew/D-4658-2012; Mishchenko, Michael/D-4426-2012 NR 17 TC 9 Z9 9 U1 0 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0096-3003 J9 APPL MATH COMPUT JI Appl. Math. Comput. PD NOV PY 2000 VL 116 IS 1-2 BP 167 EP 179 DI 10.1016/S0096-3003(99)00202-7 PG 13 WC Mathematics, Applied SC Mathematics GA 367KC UT WOS:000090059400014 ER PT J AU Kennedy, CA Carpenter, MH Lewis, RM AF Kennedy, CA Carpenter, MH Lewis, RM TI Low-storage, explicit Runge-Kutta schemes for the compressible Navier-Stokes equations SO APPLIED NUMERICAL MATHEMATICS LA English DT Article ID PARTIAL-DIFFERENTIAL EQUATIONS; INITIAL-VALUE PROBLEMS; BOUNDARY-LAYER FLOWS; NUMERICAL-SOLUTION; COMPUTATIONAL ACOUSTICS; OSCILLATING SOLUTIONS; LOW-DISSIPATION; PAIRS; STABILITY; ERROR AB The derivation of low-storage, explicit Runge-Kutta (ERK) schemes has been performed in the context of integrating the compressible Navier-Stokes equations via direct numerical simulation. Optimization of ERK methods is done across the broad range of properties, such as stability and accuracy efficiency, linear and nonlinear stability, error control reliability, step change stability, and dissipation/dispersion accuracy, subject to varying degrees of memory economization. Following van der Houwen and Wray, sixteen ERK pairs are presented using from two to five registers of memory per equation, per grid point and having accuracies from third- to fifth-order. Methods have been tested with not only DETEST, but also with the 1D wave equation. Two of the methods have been applied to the DNS of a compressible jet as well as methane-air and hydrogen-air flames. Derived 3(2) End 4(3) pairs are competitive with existing full-storage methods. Although a substantial efficiency penalty accompanies use of two- and three-register, fifth-order methods, the best contemporary full-storage methods can be nearly matched while still saving 2-3 registers of memory. (C) 2000 IMACS. Published by Elsevier Science B.V. All rights reserved. C1 Sandia Natl Labs, Combust Res Facil, Livermore, CA 94551 USA. NASA, Langley Res Ctr, Computat Methods & Simulat Branch, Hampton, VA 23681 USA. NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. RP Kennedy, CA (reprint author), Sandia Natl Labs, Combust Res Facil, Livermore, CA 94551 USA. NR 93 TC 179 Z9 182 U1 1 U2 13 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9274 J9 APPL NUMER MATH JI Appl. Numer. Math. PD NOV PY 2000 VL 35 IS 3 BP 177 EP 219 DI 10.1016/S0168-9274(99)00141-5 PG 43 WC Mathematics, Applied SC Mathematics GA 371BJ UT WOS:000165157500001 ER PT J AU Schlegel, EM Petre, R Colbert, EJM Miller, S AF Schlegel, EM Petre, R Colbert, EJM Miller, S TI A deep ROSAT HRI observation of NGC 1313 SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : spiral; galaxies : stellar content ID X-RAY SOURCES; SPIRAL GALAXY NGC-1313; INTERSTELLAR-MEDIUM; EMISSION; SUPERNOVA; SN-1978K AB We describe a series of observations of NGC 1313 using the ROSAT HRI with a combined exposure time of 183.5 ks. The observations span an interval between 1992 and 1998; the purpose of observations since 1994 was to monitor the X-ray flux of SN 1978K, one of several luminous sources in the galaxy. No diffuse emission is detected in the galaxy to a level of similar to1-2 x 10(37) ergs s(-1) arcmin(-2). A total of eight sources are detected in the summed image within the D(25) diameter of the galaxy. The luminosities of five of the eight range from similar to6 x 10(37) to similar to6 x 10(38) ergs s(-1); these sources are most likely accreting X-ray binaries, similar to sources observed in M31 and M33. The remaining three sources all emit above 10(39) ergs s(-1). We present light curves of the five brightest sources. Variability is detected at the 99.9% level in four of these. We identify one of the sources as an NGC 1313 counterpart of a Galactic X-ray source. The light curve, though crudely sampled, most closely resembles that of a Galactic black hole candidate such as GX 339-4 but with considerably higher peak X-ray luminosity. An additional seven sources lie outside the D(25) diameter and are either foreground stars or background active galactic nuclei. C1 Smithsonian Astrophys Observ, High Energy Astrophys Div, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Xray Astrophys Grp, Greenbelt, MD 20771 USA. Univ Maryland, Dept Agron, College Pk, MD 20742 USA. RP Schlegel, EM (reprint author), Smithsonian Astrophys Observ, High Energy Astrophys Div, Mail Stop 4,60 Garden St, Cambridge, MA 02138 USA. NR 36 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 NOV PY 2000 VL 120 IS 5 BP 2373 EP 2382 DI 10.1086/316804 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YK UT WOS:000165095200014 ER PT J AU Jacobson, RA AF Jacobson, RA TI The orbits of the outer Jovian satellites SO ASTRONOMICAL JOURNAL LA English DT Review DE ephemerides; planets and satellites : general; planets and satellites : individual (Jupiter) ID ASTROMETRIC OBSERVATIONS; JUPITER; OPPOSITION; EPHEMERIDES AB This article describes a fit of numerically integrated orbits for the eight outer Jovian satellites to Earth-based astrometric observations. The principal results are the epoch state vectors for the integration and a set of mean orbital elements, which approximately represent the orbits. An assessment of the quality of the fit and of the accuracy of the orbits is also provided. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jacobson, RA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 120 TC 22 Z9 23 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD NOV PY 2000 VL 120 IS 5 BP 2679 EP 2686 DI 10.1086/316817 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YK UT WOS:000165095200036 ER PT J AU Pottasch, SR Beintema, DA Feibelman, WA AF Pottasch, SR Beintema, DA Feibelman, WA TI Abundance in the planetary nebulae NGC 6537 and He2-111 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE stars : abundances; stars : emission-line, Be; ISM : planetary nebulae : general; ISM : planetary nebulae : individual : NGC 6537; ISM : planetary nebulae : individual : He2-111; infrared : ISM : lines and bands ID APPARENT MAGNITUDES; NGC-6302; SPECTRA; NGC-6537; OBJECTS; NUCLEI; STARS; RADIO AB The ISO and IUE spectra of the bipolar planetary nebulae NGC 6537 and He2-111 are presented. These spectra are combined with the spectrum in the visual wavelength region from the nebulae to obtain a complete spectrum that is corrected for extinction. The chemical abundance of the nebulae is then determined and compared to previous determinations, The abundance of the two nebulae is quite similar. A comparison is then made with the abundance of two other bipolar planetary nebulae whose abundance is also determined with the help of ISO observations. It is shown that not all bipolar nebulae have similar abundance. NGC 6445 has a much lower nitrogen to oxygen ratio, similar to NGC 7027, but still not as low as the Orion nebula. C1 Kapteyn Astron Inst, NL-9700 AV Groningen, Netherlands. SRON, Lab Space Res, NL-9700 AV Groningen, Netherlands. Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Pottasch, SR (reprint author), Kapteyn Astron Inst, POB 800, NL-9700 AV Groningen, Netherlands. EM pottasch@astro.rug.nl NR 39 TC 41 Z9 41 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 2000 VL 363 IS 2 BP 767 EP 778 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 388HK UT WOS:000166174800037 ER PT J AU Le Brun, V Smette, A Surdej, J Claeskens, JF AF Le Brun, V Smette, A Surdej, J Claeskens, JF TI Lensing properties of 7 damped Ly alpha absorbing galaxy-QSO pairs SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE galaxies : quasars : absorption lines; galaxies : halos; galaxies : ISM ID SPIRAL GALAXIES; LYMAN-ALPHA; SYSTEMS; ABSORPTION; EVOLUTION; DUST AB Le Brun et al. (1997) presented the first identifications of the galaxies giving rise to 7 intermediate redshift damped Ly alpha (DLA) absorption systems. Here, we study the gravitational lensing properties of these foreground galaxies based on their observed optical appearance and on the absence of any secondary lensed quasar image. We consider the possibility that any secondary image be hidden due to extinction by dust, but find it unlikely. We derive upper limits on the amplification factor affecting the luminosity of the background quasars; in each case, this factor is found to be less than 0.3 mag. We also obtain upper limits on the total mass of the damped Ly alpha galaxies, within radii equal to the quasar impact parameters. Mass-to-light ratios are found to be consistent with existing estimates based on X-ray emission or on motion of dwarf satellites. Although we show that lensing is not important in this sample, we note that existing DLA surveys used to determine the cosmological density of gas at z < 1 are based on samples of quasars brighter than the ones considered here and for which the amplification bias is likely to be stronger. C1 CNRS, Astron Spatiale Lab, F-13376 Marseille, France. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Opt Astron Observ, Tucson, AZ 85726 USA. Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium. RP Le Brun, V (reprint author), CNRS, Astron Spatiale Lab, BP 8, F-13376 Marseille, France. NR 21 TC 14 Z9 14 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD NOV PY 2000 VL 363 IS 3 BP 837 EP 842 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 388HL UT WOS:000166174900005 ER PT J AU Stecker, FW AF Stecker, FW TI Can gamma ray bursts produce the observed cosmic rays above 10(20) eV? SO ASTROPARTICLE PHYSICS LA English DT Article DE gamma-ray bursts; cosmic rays; theory ID ENERGY-SPECTRUM; HOST GALAXY; REDSHIFT; CUTOFF; GRB-970508; RADIATION; WELL AB It has been suggested that cosmological gamma-ray bursts (GRBs) can produce the observed flux and spectrum of cosmic rays at the highest energies. However, recent observations indicate that the redshift distribution of GRBs most likely follows that of the star formation rate in the universe, a rate which was much higher at redshifts 1.5-2 than it is today. Thus, most GRBs are at high redshifts. As a consequence, any cosmic rays emitted by these GRBs at energies above similar to 2-3 x 10(19) eV would be strongly attenuated by interactions with the 3 K background radiation. If one assumes rough equality between the energy released by GRBs in 10(-2) to 1 MeV photons, and that released in 10(20) eV cosmic rays, then less than 10% of the cosmic rays observed above 10(20) eV can be accounted for by GRBs. (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. EM stecker@twinkie.gsfc.nasa.gov RI Stecker, Floyd/D-3169-2012 NR 37 TC 44 Z9 44 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0927-6505 EI 1873-2852 J9 ASTROPART PHYS JI Astropart Phys. PD NOV PY 2000 VL 14 IS 3 BP 207 EP 210 DI 10.1016/S0927-6505(00)00122-5 PG 4 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 354XH UT WOS:000089356200005 ER PT J AU Kurczynski, P Palmer, D Seifert, H Teegarden, BJ Gehrels, N Cline, TL Ramaty, R Hurley, K Madden, NW Pehl, RH AF Kurczynski, P Palmer, D Seifert, H Teegarden, BJ Gehrels, N Cline, TL Ramaty, R Hurley, K Madden, NW Pehl, RH TI High-resolution spectroscopy of gamma-ray bursts with the transient gamma-ray spectrometer SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts; instrumentation : detectors; line : identification ID LINE SEARCH; SPECTRAL FEATURES; CYCLOTRON; ABSORPTION; ASTRONOMY; REPEATERS AB A search for spectral lines in gamma-ray bursts detected with the Transient Gamma-Ray Spectrometer has been unable to confirm their existence. The spectrometer, aboard the Wind spacecraft, has detected gamma-ray bursts and other transients since 1995. We have performed a systematic search for narrow spectral lines in gamma-ray bursts detected with this instrument that augments and extends the results of a similar search of bursts detected with BATSE. This search procedure tests for statistically significant lines at all possible times and durations during a burst using the method of maximum likelihood and C-statistic. Simulations demonstrated the effectiveness of this procedure, particularly on Poisson distributed data, for distinguishing real features from statistical fluctuations. The most promising line candidates were consistent with chance fluctuations, given the large number of spectra searched. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94702 USA. RP Kurczynski, P (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. NR 22 TC 3 Z9 3 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2000 VL 543 IS 1 BP 77 EP 89 DI 10.1086/317069 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 374XB UT WOS:000165368800007 ER PT J AU Tanihata, C Takahashi, T Kataoka, J Madejski, GM Inoue, S Kubo, H Makino, F Mattox, JR Kawai, N AF Tanihata, C Takahashi, T Kataoka, J Madejski, GM Inoue, S Kubo, H Makino, F Mattox, JR Kawai, N TI Rapid synchrotron flares from BL Lacertae detected by ASCA and RXTE SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL Lacertae objects : individual (BL Lacertae); galaxies : active; radiation mechanisms : nonthermal; X-rays : galaxies ID SPECTRAL ENERGY-DISTRIBUTIONS; GAMMA-RAY; RELATIVISTIC JETS; 1997 OUTBURST; RADIO-SOURCES; BLAZARS; VARIABILITY; RADIATION; EMISSION; ACCELERATION AB We report the variable X-ray emission from BL Lacertae detected in the ASCA ToO observation conducted during the EGRET and RXTE pointings, coincident with the 1997 July outburst. The source showed a historically high state of X-ray, optical, and gamma -ray emission, with its 2-10 keV flux peaking at similar to3.3 x 10(-11) ergs cm(-2) s(-1). This is more than 3 times higher than the value measured by ASCA in 1995. Ne detected two rapid flares that occurred only in the soft X-ray band, while the hard X-ray flux also increased, but decayed with a much longer timescale. Together with the requirement of a very steep and varying power law dominating the soft X-ray band in addition to the hard power law, we suggest that both the high-energy end of the synchrotron spectrum and the hard inverse Compton spectrum were visible in this source during the outburst. We discuss the possible origins of the observed variability timescales, and interpret the short timescales of the soft X-ray variability as reflecting the size of the emission region. C1 Inst Space & Aeronaut Studies, Sagamihara, Kanagawa 2298510, Japan. Univ Tokyo, Dept Phys, Bunkyo Ku, Tokyo 1130033, Japan. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Natl Astron Observ, Theoret Astrophys Div, Mitaka, Tokyo 1818588, Japan. Tokyo Inst Technol, Dept Phys, Tokyo 1528551, Japan. Natl Space Dev Agcy Japan, Space Utilizat Res Program, Tsukuba Space Ctr, Tsukuba, Ibaraki 3058505, Japan. Boston Univ, Dept Astron, Boston, MA 02215 USA. Inst Phys & Chem Res, Wako, Saitama 3510198, Japan. RP Tanihata, C (reprint author), Inst Space & Aeronaut Studies, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 2298510, Japan. OI Sako, Chiharu/0000-0003-3243-3954 NR 43 TC 24 Z9 24 U1 0 U2 5 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2000 VL 543 IS 1 BP 124 EP 130 DI 10.1086/317086 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 374XB UT WOS:000165368800011 ER PT J AU Trewhella, M Davies, JI Alton, PB Bianchi, S Madore, BF AF Trewhella, M Davies, JI Alton, PB Bianchi, S Madore, BF TI ISO long wavelength spectrograph observations of cold dust in galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; galaxies : halos; galaxies : ISM; infrared : galaxies ID SPIRAL GALAXIES; SURFACE BRIGHTNESS; DARK-MATTER; DISK; GAS; MODELS; EXTINCTION; STELLAR; NGC-891; HALOS AB We describe observations of five nearby galaxies obtained using the Long Wavelength Spectrograph (LWS) on the Infrared Space Observatory (ISO). We observed five galaxies, using spectrograph apertures positioned at the galactic center and in the outskirts of the disk, to compare the spectral energy distribution of the emitting dust at different positions. The central spectra are typical of those inferred previously from IRAS data; peaking at about 100 mum with estimated dust temperatures of T-d = 30-35 K. However, there is a rapid change in the spectral energy distribution with increasing galactocentric distance. In the outer regions the spectra are flat, or still rising, out to 197 mum, indicating a predominantly cold dust component with T-d < 20 K. In the central regions, the inferred cold dust component is 2-10 times more massive than the warm dust, and it increasingly dominates the mass and spectral energy distribution in the outer regions. We discuss reasons for believing that emission beyond 150 mum in disk galaxies is associated with a separate component of dust with an extended distribution that may be associated with a possible molecular halo. C1 CALTECH, Jet Prop Lab, IPAC, Pasadena, CA 91125 USA. Univ Wales, Dept Phys & Astron, Cardiff CF2 3YB, S Glam, Wales. NASA, IPAC Extragalact Database NED, Pasadena, CA 91125 USA. Carnegie Inst Washington Observ, Pasadena, CA 91101 USA. RP Trewhella, M (reprint author), CALTECH, Jet Prop Lab, IPAC, 770 S Wilson Ave, Pasadena, CA 91125 USA. OI Bianchi, Simone/0000-0002-9384-846X NR 32 TC 25 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2000 VL 543 IS 1 BP 153 EP 160 DI 10.1086/317083 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 374XB UT WOS:000165368800014 ER PT J AU Kuntz, KD Snowden, SL AF Kuntz, KD Snowden, SL TI Deconstructing the spectrum of the soft X-ray background SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxy : general; ISM : general; X-rays : galaxies; X-rays : general ID DIFFUSE IONIZED-GAS; INTERSTELLAR-MEDIUM; THIN PLASMAS; ROSAT OBSERVATIONS; PSPC OBSERVATIONS; MAGELLANIC-CLOUD; NEUTRAL HYDROGEN; MOLECULAR CLOUD; SPIRAL GALAXIES; GALACTIC CORONA AB The soft X-ray background in the 0.1-1.0 keV band is known to be produced by at least three sources: the Local Hot Bubble (LHB), the extragalactic power law (EPL), and a seemingly Galactic component that lies outside the bulk of the absorption that is caused by the ISM of the Galactic disk. This last component, which we call the "transabsorption emission" (TAE), has been modeled by a number of groups who have derived disparate measures of its temperature. The differences have arisen from differing assumptions about the structure of the emitting gas and unrecognized methodological difficulties. In particular, spectral fitting methods do not uniquely separate the TAE from the foreground emission that is caused by the LHB. This " degeneracy" can be resolved using the angular variation of the absorption of the TAE. We show that the TAE cannot be characterized by a single thermal component; no single component model can be consistent with both the spectral energy distribution of the TAE and the angular variation caused by absorption by the Galactic disk. We use the angular anticorrelation of the ROSAT All-Sky Survey (RASS) with the Galactic absorption to separate local from distant emission components and to fit the spectral energy distribution of the resulting distant emission. We find that the emission is best described by a two-thermal-component model with log T(S)= 6.06+/-(0.19)(0.20) and log T(H)= 6.46+/-(0.12)(0.08). This two-thermal-component TAE fits the ROSAT spectral energy distribution significantly better than single-component models and is consistent with both angular variation and spectral constraints. C1 Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kuntz, KD (reprint author), Univ Maryland, Dept Astron, College Pk, MD 20742 USA. EM kuntz@astro.umd.edu; snowden@lheavx.gsfc.nasa.gov RI Snowden, Steven/D-5292-2012 NR 81 TC 160 Z9 160 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 NOV 1 PY 2000 VL 543 IS 1 BP 195 EP 215 DI 10.1086/317071 PN 1 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 374XB UT WOS:000165368800017 ER PT J AU Akeson, RL Ciardi, DR van Belle, GT Creech-Eakman, MJ Lada, EA AF Akeson, RL Ciardi, DR van Belle, GT Creech-Eakman, MJ Lada, EA TI Infrared interferometric observations of young stellar objects SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; stars : pre-main-sequence ID PALOMAR TESTBED INTERFEROMETER; BASE-LINE INTERFEROMETRY; T-TAURI STARS; DISKS AB We present infrared observations of four young stellar objects made using the Palomar Testbed Interferometer (PTI). For three of the sources, T Tau, MWC 147, and SU Aur, the 2.2 mum emission is resolved at the Pn's nominal fringe spacing of 4 mas, while the emission region of AB Aur is overresolved on this scale. We fit the observations with simple circumstellar material distributions and compare our data to the predictions of accretion disk models inferred from spectral energy distributions. We find that the infrared emission region is tenths of an AU in size for T Tau and SU Aur and similar to1 AU for MWC 147. C1 CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Florida, Dept Astron, Gainesville, FL 32611 USA. RP Akeson, RL (reprint author), CALTECH, Ctr Infrared Proc & Anal, MS 100-22,770 S Wilson Ave, Pasadena, CA 91125 USA. NR 22 TC 55 Z9 55 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2000 VL 543 IS 1 BP 313 EP 317 DI 10.1086/317111 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 374XB UT WOS:000165368800029 ER PT J AU Thompson, C Duncan, RC Woods, PM Kouveliotou, C Finger, MH Van Paradus, J AF Thompson, C Duncan, RC Woods, PM Kouveliotou, C Finger, MH Van Paradus, J TI Physical mechanisms for the variable spin-down and light curve of SGR 1900+14 SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : general; stars : individual (SGR 1900+14); X-rays : bursts ID SOFT GAMMA REPEATER; X-RAY PULSAR; MAGNETIZED NEUTRON-STARS; INTERPLANETARY NETWORK LOCALIZATION; SUPERNOVA REMNANT; VORTEX CREEP; STATISTICAL PROPERTIES; RAPID BURSTER; 1E 2259+586; FIELD AB We consider the physical implications of the rapid spin-down of soft gamma repeater SGR 1900 + 14 reported by Woods and colleagues in 1999. During an 80 day interval between 1998 June and the large outburst on 1998 August 27, the mean spin-down rate increased by a factor of 2.3, resulting in a positive period offset of DeltaP/P = 10(-4). A radiation-hydrodynamical outflow associated with the August 27 event could impart the required torque, but only if the dipole magnetic field is stronger than similar to 10(14) G and the outflow lasts longer and/or is more energetic than the observed X-ray flare. A positive period increment is also a natural consequence of a gradual, plastic deformation of the neutron star crust by an intense magnetic field, which forces the neutron superfluid to rotate more slowly than the crust. Sudden unpinning of the neutron vortex lines during the August 27 event would then induce a glitch opposite in sign to those observed in young pulsars, but of a much larger magnitude as a result of the slower rotation. The change in the persistent X-ray light curve following the August 27 event is ascribed to continued particle heating in the active region of that outburst. The enhanced X-ray output can be powered by a steady current flowing through the magnetosphere, induced by the twisting motion of the crust. The long-term rate of spin-down appears to be accelerated with respect to a simple magnetic dipole torque. Accelerated spin-down of a seismically active magnetar will occur when its persistent output of Alfven waves and particles exceeds its spin-down luminosity or if particle flows modulate the ratio of conduction to displacement currents in the outer magnetosphere. We suggest that SGRs experience some episodes of relative inactivity, with diminished P, and that such inactive magnetars are observed as anomalous X-ray pulsars (AXPs). The reappearance of persistent X-ray emission from SGR 1900+14 within one day of the August 27 event provides strong evidence that the persistent emission is not powered by accretion. C1 Univ N Carolina, Dept Phys & Astron, Chapel Hill, NC 27599 USA. Univ Texas, Dept Astron, Austin, TX 78712 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. RP Thompson, C (reprint author), Univ N Carolina, Dept Phys & Astron, Philips Hall, Chapel Hill, NC 27599 USA. NR 77 TC 83 Z9 84 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 NOV 1 PY 2000 VL 543 IS 1 BP 340 EP 350 DI 10.1086/317072 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 374XB UT WOS:000165368800033 ER PT J AU Gotthelf, EV Ueda, Y Fujimoto, R Kii, T Yamaoka, K AF Gotthelf, EV Ueda, Y Fujimoto, R Kii, T Yamaoka, K TI Restoration of the ASCA source position accuracy SO ASTROPHYSICAL JOURNAL LA English DT Article DE instrumentation : miscellaneous; space vehicles : instruments; X-rays : general ID DEEP ROSAT FIELDS; LARGE SKY SURVEY; X-RAY SOURCE; SPECTRAL PROPERTIES; IDENTIFICATION; AGN AB We present a calibration of the absolute pointing accuracy of the Advanced Satellite for Cosmology and Astrophysics (ASCA) which allows us to compensate for a large error (up to 1') in the derived source coordinates. We parameterize a temperature dependent deviation of the attitude solution which is responsible for this error. By analyzing ASCA coordinates of 100 bright active galactic nuclei, we show that it is possible to reduce the uncertainty in the sky position for any given observation by a factor of 4. The revised 90% error circle radius is then 12", consistent with preflight specifications, effectively restoring the full ASCA pointing accuracy. Herein, we derive an algorithm which compensates for this attitude error and present an internet-based table to be used to correct post facto the coordinate of all ASCA observations. While the above error circle is strictly applicable to data taken with the on-board Solid-state Imaging Spectrometers (SISs), similar coordinate corrections are derived for data obtained with the Gas Imaging Spectrometers (GISs), which, however, have additional instrumental uncertainties. The 90% error circle radius for the central 20' diameter of the GIS is 24". The large reduction in the error circle area for the two instruments offers the opportunity to greatly enhance the search for X-ray counterparts at other wavelengths. This has important implications for current and future ASCA source catalogs and surveys. C1 NASA, Goddard Space Flight Ctr, ASCA Guest Observer Facil, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. RP Gotthelf, EV (reprint author), Columbia Univ, Columbia Astrophys Lab, 550 W 120th St, New York, NY 10027 USA. NR 27 TC 29 Z9 31 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2000 VL 543 IS 1 BP 417 EP 424 DI 10.1086/317093 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 374XB UT WOS:000165368800041 ER PT J AU Hollis, JM Pedelty, JA Forster, JR White, SM Boboltz, DA Alcolea, J AF Hollis, JM Pedelty, JA Forster, JR White, SM Boboltz, DA Alcolea, J TI R Aquarii: Constraints on the rotational period of the long-period variable SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; masers; stars : individual (R Aquarii); stars : rotation; stars : variables : other; techniques : interferometric ID MASER EMISSION; RESOLUTION; STARS; SPECTROSCOPY AB We report Very Large Array (VLA) observations taken in 1996 November and 1998 May of the nu = 1, J = 1-0, SiO maser line and BIMA array observations taken in 1999 December and 2000 February of the nu = 1, J = 2-1, SiO maser line associated with the long-period variable (LPV) in the R Aquarii binary system that suggest rotation of the maser shell. From these interferometric data cubes, we determine that the maser shell rotation axis is approximately northeast-southwest, thus aligning approximately with the direction of the R Aqr jet; the sense of the maser shell rotation is such that northwest is approaching and southeast is receding; the period of rotation is similar to 17 yr. Alternatively, co-adding 72 time series spectra of the nu = 1, J = 1-0, SiO maser line obtained during the period 1984 July-1990 May with a single-dish antenna, we constructed a composite spectral emission envelope that shows the LSR velocity limits of maser emission over this epoch. From this composite spectral emission envelope and Very Long Baseline Array observations in 1996 February of the 1, J = 1-0, SiO maser line, which show the maximal spatial extent of the maser shell, we obtain a shell rotation period of similar to 18 yr, which is in excellent agreement with the VLA and BIMA array results and represents the maximum rotation period of the LPV if corotating with the maser shell. On the other hand, we obtain a minimum rotation period for the LPV of similar to5 yr if the LPV supplies material to the maser shell under the constraint of conservation of angular momentum. The similar to5-18 yr range for the rotational period of the LPV determined here and the similar to 18 yr rotational period for the hot companion determined by previous investigators suggest that tidal effects at successive periastron passages in the R Aqr binary system are tending to synchronize these stellar rotational periods to the orbital period of similar to 44 yr. C1 NASA, Goddard Space Flight Ctr, Earth & Space Data Comp Div, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. Hat Creek Radio Observ, Hat Creek, CA 96040 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. USN Observ, Washington, DC 20392 USA. Observ Astron Nacl, E-2880 Alcala De Henares, Spain. RP Hollis, JM (reprint author), NASA, Goddard Space Flight Ctr, Earth & Space Data Comp Div, Code 930, Greenbelt, MD 20771 USA. NR 10 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 SOUTH WOODLAWN AVE, CHICAGO, IL 60637-1603 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD NOV 1 PY 2000 VL 543 IS 1 BP L81 EP L84 DI 10.1086/318164 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 374XD UT WOS:000165369000019 ER PT J AU Chatzichristou, ET AF Chatzichristou, ET TI Multicolor optical imaging of infrared-warm Seyfert galaxies. I. Introduction and sample selection SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE galaxies : active; galaxies : interactions; galaxies : photometry; galaxies : Seyfert; infrared : galaxies ID BRIGHT-NUCLEUS GALAXIES; EMISSION-LINE GALAXIES; POINT-SOURCE CATALOG; IRAS OBSERVATIONS; SOUTHERN COMPACT; ACTIVE GALAXIES; UNIFIED MODELS; SPECTROSCOPY; LUMINOSITY; QUASARS AB The standard AGN unification models attempt to explain the diversity of observed AGN types by a few fundamental parameters, where orientation effects play a paramount role. Whether other factors, such as the evolutionary stage and the host galaxy properties are equally important parameters for the AGN diversity, is a key issue that we are addressing with the present data. Our sample of IR-selected Seyfert galaxies is based on the important discovery that their integrated IR spectrum contains an AGN signature, the "warm" 25-60 mum color index. This being an almost isotropic property, our sample is much less affected by orientation/obscuration effects compared to most Seyfert samples. It therefore provides a test-bed for the orientation-dependent models of Seyferts, involving dusty tori. We have obtained multicolor broadband and narrowband imaging for a sample of mid-IR "warm" (less than or equal to alpha ((25,60)) less than or equal to 0) Seyferts and for a control sample of mid-IR "cold" (alpha ((25,60)) less than or equal to -1.5) galaxies. The two samples span similar ranges of far-IR colors (similar to -3.0 less than or equal to alpha ((60,100)) less than or equal to 0.5). The warm sample contains 21 Seyfert 1 and 33 Seyfert 2 galaxies with log L-FIR = 9.6-11.8 and z = 0.01-0.08, including some of the most extreme warm sources (L-60 greater than or equal to 10(11) L.). The cold sample contains 16 IRAS sources selected to match the warm galaxies in redshift and luminosity range, but show a variety of nuclear types (Seyfert 1, Seyfert 2, and starburst). In the present paper we describe in some detail the sample selection and briefly discuss their IR properties. We then give an overview of the data collected and present broadband images for all our objects. Finally, we summarize the main issues that will be addressed with these data in a series of forthcoming papers: (i) the orientation versus evolutionary Seyfert unification schemes and (ii) the origin of mid-IR excess in the warm Seyfert sample. C1 Leiden Observ, NL-2300 RA Leiden, Netherlands. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Chatzichristou, ET (reprint author), Leiden Observ, POB 9513, NL-2300 RA Leiden, Netherlands. NR 48 TC 9 Z9 9 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0067-0049 EI 1538-4365 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD NOV PY 2000 VL 131 IS 1 BP 71 EP 94 DI 10.1086/317362 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385ZY UT WOS:000166036100005 ER PT J AU Charpinet, S Fontaine, G Brassard, P Dorman, B AF Charpinet, S Fontaine, G Brassard, P Dorman, B TI Adiabatic survey of subdwarf B star oscillations. I. Pulsation properties of a representative evolutionary model SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE stars : interiors; stars : oscillations; subdwarfs ID EVOLVED STELLAR POPULATIONS; CRYSTALLINE LATTICE PHASE; OXYGEN-ENHANCED MODELS; GLOBULAR-CLUSTER STARS; DA WHITE-DWARFS; HORIZONTAL-BRANCH; THERMAL-CONDUCTIVITIES; DENSE MATTER; ULTRAVIOLET-RADIATION; ELLIPTIC GALAXIES AB We present the first results of a large, systematic adiabatic survey of the pulsation properties of models of subdwarf B (sdB) stars. This survey is aimed at providing the most basic theoretical data with which to analyze the asteroseismological properties of the recently discovered class of pulsating sdB stars (the EC 14026 stars). Such a theoretical framework has been lacking up to now. In this paper, the first of a series of three, an adiabatic pulsation code is used to compute, in the 80-1500 s period window, the radial (l = 0) and nonradial (from l = 1 up to l = 3) oscillation modes for a representative evolutionary model of subdwarf B stars. Quantities such as the periods, kinetic energies, first-order rotational splitting coefficients, eigenfunctions, and weight functions are given by the code, providing a complete set of very useful diagnostic tools with which to study the mode properties. The main goal is to determine how these quantities relate to the internal structure of B subdwarfs, a crucial and necessary step if one wants to eventually apply the tools of asteroseismology to EC 14026 stars. All modes (p, f, and g) were considered in order to build the most complete picture we can have on pulsations in these stars. In that context, we show that 9-modes are essentially deep interior modes oscillating mainly in the radiative helium-rich core (but not in the convective nucleus), while p-modes are shallower envelope modes. We demonstrate that g-modes respond to a trapping/confinement phenomenon induced mainly by the He/H chemical transition between the H-rich envelope and the He-rich core of subdwarf B stars. This phenomenon is very similar in nature to the g-mode trapping and confinement mechanisms observed in pulsating white dwarf models. We emphasize that p-modes may also experience distortions of their period distribution due to this He/H transition, although these are not as pronounced as in the g-mode case. These phenomena are of great interest as they can potentially provide powerful tools for probing the internal structure of these objects, in particular, with respect to constraining the mass of their H-rich envelope. The results given in this first paper form the minimal background on pulsation mode characteristics in sdB stars. Upcoming discussions on additional mode properties in subdwarf B star models (Paper II and Paper III of this series) will strongly rely on these basic results since they provide essential guidance in understanding mode period behaviors as functions of B subdwarf stellar parameters and/or evolution. C1 Canada France Hawaii Telescope Corp, Kamuela, HI 96743 USA. Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada. NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Charpinet, S (reprint author), Canada France Hawaii Telescope Corp, POB 1597, Kamuela, HI 96743 USA. NR 52 TC 59 Z9 60 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD NOV PY 2000 VL 131 IS 1 BP 223 EP 247 DI 10.1086/317359 PG 25 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385ZY UT WOS:000166036100008 ER PT J AU Fryxell, B Olson, K Ricker, P Timmes, FX Zingale, M Lamb, DQ MacNeice, P Rosner, R Truran, JW Tufo, H AF Fryxell, B Olson, K Ricker, P Timmes, FX Zingale, M Lamb, DQ MacNeice, P Rosner, R Truran, JW Tufo, H TI Flash: An adaptive mesh hydrodynamics code for modeling astrophysical thermonuclear flashes SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE equation of state; hydrodynamics; methods : numerical; nuclear reactions, nucleosynthesis, abundances; stars : general ID MONTE-CARLO CALCULATIONS; ONE-COMPONENT PLASMA; NOVA OUTBURSTS; WHITE-DWARFS; DIFFERENTIAL-EQUATIONS; N-DEPENDENCE; DETONATIONS; SIMULATIONS; STATE; REFINEMENT AB We report on the completion of the first version of a new-generation simulation code, FLASH. The FLASH code solves the fully compressible, reactive hydrodynamic equations and allows for the use of adaptive mesh refinement. It also contains state-of-the-art modules for the equations of state and thermonuclear reaction networks. The FLASH code was developed to study the problems of nuclear flashes on the surfaces of neutron stars and white dwarfs, as well as in the interior of white dwarfs. We expect, however, that the FLASH code will be useful for solving a wide variety of other problems. This first version of the code has been subjected to a large variety of test cases and is currently being used for production simulations of X-ray bursts, Rayleigh-Taylor and Richtmyer-Meshkov instabilities, and thermonuclear flame fronts. The FLASH code is portable and already runs on a wide variety of massively parallel machines, including some of the largest machines now extant. C1 Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. Univ Chicago, Ctr Astrophys Thermonucl Flashes, Chicago, IL 60637 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Chicago, Dept Comp Sci, Chicago, IL 60637 USA. RP Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA. RI MacNeice, Peter/F-5587-2012; OI Zingale, Michael/0000-0001-8401-030X NR 70 TC 963 Z9 967 U1 4 U2 29 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0067-0049 EI 1538-4365 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD NOV PY 2000 VL 131 IS 1 BP 273 EP 334 DI 10.1086/317361 PG 62 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385ZY UT WOS:000166036100010 ER PT J AU Rutledge, RE Brunner, RJ Prince, TA Lonsdale, C AF Rutledge, RE Brunner, RJ Prince, TA Lonsdale, C TI XID: Cross-association of ROSAT/Bright Source Catalog X-ray sources with USNO A-2 optical point sources SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE catalogs; X-rays : general ID ALL-SKY SURVEY; GALACTIC PLANE SURVEY; GUIDE STAR CATALOG; NEUTRON-STAR; IDENTIFICATION; SAMPLE AB We quantitatively cross-associate the 18,811 ROSAT Bright Source Catalog (RASS/BSC) X-ray sources with optical sources in the USNO A-2 catalog, calculating the probability of unique association (P-id) between each candidate within 75 " of the X-ray source position, on the basis of optical magnitude and proximity. We present catalogs of RASS/BSC sources for which P-id > 98%, P-id > 90%, and P-id > 50%, which contain 2705, 5492, and 11,301 unique USNO A-2 optical counterparts respectively down to the stated level of significance. Together with identifications of objects not cataloged in USNO A-2 due to their high surface brightness (M31, M32,...) and optical pairs, we produced a total of 11,803 associations to a probability of P-id > 50%. We include in this catalog a list of objects in the SIMBAD database within 10 " of the USNO A-2 position, as an aid to identification and source classification. This is the first RASS/BSC counterpart catalog which provides a probability of association between each X-ray source and counterpart, quantifying the certainty of each individual association. The catalog is more useful than previous catalogs which either rely on plausibility arguments for association or do not aid in selecting a counterpart between multiple off-band sources in the field. Sources of high probability of association can be separated out, to produce high-quality lists of classes (Seyfert 1/2s, QSOs, RS CVns) desired for targeted study, or for discovering new examples of known classes (or new classes altogether) through the spectroscopic classification of securely identified but unclassified USNO A-2 counterparts. Low P-id associations can be used for statistical studies and follow-on investigation-for example, performing follow-up spectroscopy of the many low-mass stars to search for signatures of coronal emission, or to investigate the relationship between X-ray emission and classes of sources not previously well-studied for their X-ray emissions (such as pulsating variable stars). We find that a fraction similar to 65.8% of RASS/BSC sources have an identifiable optical counterpart, down to the magnitude limit of the USNO A-2 catalog which could be identified by their spatial proximity and high optical brightness. C1 CALTECH, Div Phys Math & Astron, Pasadena, CA 91107 USA. CALTECH, JPL, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. RP Rutledge, RE (reprint author), CALTECH, Div Phys Math & Astron, MS 220-47, Pasadena, CA 91107 USA. NR 25 TC 49 Z9 49 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD NOV PY 2000 VL 131 IS 1 BP 335 EP 353 DI 10.1086/317363 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 385ZY UT WOS:000166036100011 ER PT J AU Bhatia, AK Eissner, W AF Bhatia, AK Eissner, W TI Atomic data and spectral line intensities for FeVIII SO ATOMIC DATA AND NUCLEAR DATA TABLES LA English DT Article ID POTASSIUM ISOELECTRONIC SEQUENCE; ELECTRON-IMPACT EXCITATION; OSCILLATOR-STRENGTHS; FE-VIII; TRANSITION-PROBABILITIES; MN-VII; CR-VI; WAVELENGTHS; IONS; XI AB Electron impact collision strengths, energy levels, oscillator strengths and spontaneous radiative decay rates are calculated for Fe VIII. The configurations used are 3p(6)3d, 3p(5)3d(2), 3p(6)4s, 3p(6)4p, and 3p(5)3d4s giving rise to 73 fine-structure levels in intermediate coupling. Collision strengths are calculated at four incident energies, 10, 30, 50, and 70 Ry. Excitation rate coefficients are calculated by assuming a Maxwellian electron velocity distribution at an electron temperature of log T-e(K) = 5.57, corresponding to maximum abundance of Fe VIII. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level, populations are solved at electron densities 10(8)-10(14) cm(-3). Relative spectral line intensities are calculated. Proton excitation rates and solar blackbody radiative excitation are also included in the statistical equilibrium equations. (C) 2000 Academic Press. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Inst Theoret Phys, D-70550 Stuttgart, Germany. RP Bhatia, AK (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 33 TC 5 Z9 5 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0092-640X J9 ATOM DATA NUCL DATA JI Atom. Data Nucl. Data Tables PD NOV PY 2000 VL 76 IS 2 BP 270 EP 346 DI 10.1006/adnd.2000.0845 PG 77 WC Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Physics GA 390YZ UT WOS:000166328500004 ER PT J AU Bowles, S Ursin, H Picano, J AF Bowles, S Ursin, H Picano, J TI Aircrew perceived stress: Examining crew performance, crew position and captains personality SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE aircrew; aviation; leadership; performance; personality; pilots; stress AB This study was conducted at NASA Ames Research Center as a part of a larger research project assessing the impact of captain's personality on crew performance and perceived stress in 24 air transport crews (5). Three different personality types for captains were classified based on a previous cluster analysis (3). Crews were comprised of three crewmembers: captain, first officer, and second officer/flight engineer. A total of 72 pilots completed a 1.5-d full-mission simulation of airline operations including emergency situations in the Ames Manned Vehicle System Research Facility B-727 simulator. Crewmembers were tested for perceived stress on four dimensions of the NASA Task Load Index after each of five flight legs. Crews were divided into three groups based on rankings from combined error and rating scores. High performance crews (who committed the least errors in flight) reported experiencing less stress in simulated flight than either low or medium crews. When comparing crew positions for perceived stress over all the simulated flights no significant differences were found. However, the crews led by the "Right Stuff" (e.g., active, warm, confident, competitive, and preferring excellence and challenges) personality type captains typically reported less stress than crewmembers led by other personality types. C1 USAREC, Command Psychol Operat, Soldier Support Inst, Ft Jackson, SC 29207 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Bergen, Inst Biol & Med Psychol, Bergen, Norway. Univ Calif Davis, Dept Psychiat, Davis, CA 95616 USA. RP Bowles, S (reprint author), USAREC, Command Psychol Operat, Soldier Support Inst, 10000 Hampton Pkwy, Ft Jackson, SC 29207 USA. NR 13 TC 12 Z9 12 U1 1 U2 3 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 2000 VL 71 IS 11 BP 1093 EP 1097 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 371CE UT WOS:000165159600002 PM 11086661 ER PT J AU Arnaud, SB Wolinsky, I Fung, P Vernikos, J AF Arnaud, SB Wolinsky, I Fung, P Vernikos, J TI Dietary salt and urinary calcium excretion in a human bed rest spaceflight model SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE dietary salt; urinary calcium excretion; urinary cAMP; parathyroid hormone; bed rest ID ABSORPTION; TRANSPORT; SODIUM; RAT AB Background: Dietary salt is known to increase the excretion of urinary calcium (Ca). To determine the potential role of dietary sodium (Na) on the calciuria associated with a spaceflight simulation model, we evaluated urinary Ca in two groups of bed rest subjects fed either high or low normal amounts of salt. Methods: We analyzed urinary Ca excretion expressed in terms of creatinine (UCa/Cr), fractional Ca excretion (FECa), and urinary cAMP (UCAMP) as an index of parathyroid function, in the urine of 30-50-yr-old male volunteers for 6 degrees head down tilt bed rest studies. Dietary Na was in the high normal range (190 mmol.d(-1)) in 8 men for 7 d (HiNa), and in the low normal range (114 mmol.d(-1)) in 11 men for 30 d (LoNa) bed rest. Dietary Ca averaged 20 mmol.d(-1) in both studies. Results: Within the first 3 bed rest days, subjects in the HiNa study showed increases in UCa/Cr (0.1130 +/- 0.05 to 0.161 +/- 0.05, p < 0.002) and in FECa (1.95 0.70 to 3.19 +/-. 0.93, p < 0.001); those in LoNa showed no change in UCa/Cr (0.125 0.06 to 0.121 +/- 0.07, NS) or FECa (1.93 +/- 0.75 to 2.22 +/- 0.63). After the 5th bed rest day UCa/Cr stabilized at similar levels in both dietary groups. UCAMP decreased 20% during the first week of bed rest with HiNa, but not until the third week with LoNa diets (p < 0.05). Conclusion: These findings implicate high salt diets in Ca excretion in a spaceflight model and suggest that low normal salt diets may reduce early calciuria associated With spaceflight. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. Univ Houston, Dept Human Dev, Houston, TX USA. RP Arnaud, SB (reprint author), NASA, Ames Res Ctr, Div Life Sci, SL 239-11, Moffett Field, CA 94035 USA. NR 35 TC 13 Z9 13 U1 0 U2 2 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 2000 VL 71 IS 11 BP 1115 EP 1119 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 371CE UT WOS:000165159600006 PM 11086665 ER PT J AU McMonigal, KA Braverman, LE Dunn, JT Stanbury, JB Wear, ML Hamm, PB Sauer, RL Billica, RD Pool, SL AF McMonigal, KA Braverman, LE Dunn, JT Stanbury, JB Wear, ML Hamm, PB Sauer, RL Billica, RD Pool, SL TI Thyroid function changes related to use of iodinated water in the US Space Program SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE iodine; potable water; thyroid function tests; US Space Program; astronauts ID ANTITHYROID PEROXIDASE ANTIBODIES; PURIFICATION; PREVALENCE; THYROTOXICOSIS; AUTOIMMUNE; DISEASE; SERUM AB Background: The National Aeronautics and Space Administration (NASA) has used iodination as a method of microbial disinfection of potable water systems in U.S. spacecraft and long-duration habitability modules. A review of thyroid function tests of NASA astronauts who had consumed iodinated water during spaceflight was conducted. Methods: Thyroid function tests of all past and present astronauts were reviewed. Medical records of astronauts with a diagnosis of thyroid disease were reviewed, iodine consumption by space crews from water and food was determined. Serum thyroid-stimulating hormone (TSH) and urinary iodine excretion from space crews were measured following modification of the Space Shuttle potable water system to remove most of the iodine. Results: Mean TSH significantly increased in 134 astronauts who had consumed iodinated water during spaceflight. Serum TSH, and urine iodine levels of Space Shuttle crewmembers who flew following modification of the potable water supply system to remove iodine did not show-a statistically significant change. There was no evidence supporting association between clinical thyroid disease and the number of spaceflights, amount of iodine consumed, or duration of iodine exposure. Conclusions: It is suggested that pharmacological doses of iodine consumed by astronauts transiently decrease thyroid function, as reflected by elevated serum TSH values. Although adverse effects of excess iodine consumption in susceptible individuals are well documented, exposure to high doses of iodine during spaceflight did not result in a statistically significant increase in long-term thyroid disease in the astronaut population. C1 NASA, Lyndon B Johnson Space Ctr, Space & Life Sci Directorate, Clin Labs, Houston, TX 77058 USA. Boston Med Ctr, Dept Med, Boston, MA USA. Univ Virginia, Dept Med, Charlottesville, VA USA. MIT, Boston, MA USA. Wyle Labs, Life Sci Syst & Serv, Houston, TX USA. RP McMonigal, KA (reprint author), NASA, Lyndon B Johnson Space Ctr, Space & Life Sci Directorate, Clin Labs, Mail Code SD 2,2101 NASA Rd 1, Houston, TX 77058 USA. NR 25 TC 17 Z9 19 U1 1 U2 3 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 2000 VL 71 IS 11 BP 1120 EP 1125 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 371CE UT WOS:000165159600007 PM 11086666 ER PT J AU Wade, CE Ortiz, RM Baer, LA AF Wade, CE Ortiz, RM Baer, LA TI Increases in body mass of rats during spaceflight: Models and measurements SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE hypergravity; centrifugation; body weight ID MESSENGER-RNA LEVELS; SKELETAL-MUSCLE; SPACE-FLIGHT; YOUNG-RATS; BONE; CENTRIFUGATION; METABOLISM; GRAVITY; GROWTH; BETA AB To test the hypothesis that the body mass of rats is increased during spaceflight, we developed two models from the literature and obtained mass measurements during spaceflight. From studies of centrifugation (hypergravity), there is a reduction in body mass of rats dependent on the exposure gravity level. From data in 18 publications on rats subjected to hypergravity by centrifugation, we developed a model that predicted a 27%. increase in body mass during the microgravity of spaceflight. Following spaceflight, with an increase in gravity on return to Earth, there Is a reduction in body mass of rats for over 3 d. We related the reduction in body mass after spaceflight to the time alter landing that mass measurements were made. From data in 23 publications on rats returning from spaceflight, we developed a model that predicted a 19% increase in body mass during spaceflight. Measurement of body mass of rats on days 6 and 10 of spaceflight found a 7 and 9% increase compared with ground control animals. The increase in body mass during spaceflight suggests that the rat may provide a viable model for metabolic studies in which changes during spaceflight may be predicted in parr by ground-based hypergravity studies. C1 NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. RP Wade, CE (reprint author), NASA, Ames Res Ctr, Div Life Sci, MS 239-11, Moffett Field, CA 94035 USA. NR 54 TC 5 Z9 5 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 USA SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD NOV PY 2000 VL 71 IS 11 BP 1126 EP 1130 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 371CE UT WOS:000165159600008 PM 11086667 ER PT J AU Peppler, RA Bahrmann, CP Barnard, JC Campbell, JR Cheng, MD Ferrare, RA Halthore, RN Heilman, LA Hlavka, DL Laulainen, NS Lin, CJ Ogren, JA Poellot, MR Remer, LA Sassen, K Spinhirne, JD Splitt, ME Turner, DD AF Peppler, RA Bahrmann, CP Barnard, JC Campbell, JR Cheng, MD Ferrare, RA Halthore, RN Heilman, LA Hlavka, DL Laulainen, NS Lin, CJ Ogren, JA Poellot, MR Remer, LA Sassen, K Spinhirne, JD Splitt, ME Turner, DD TI ARM Southern Great Plains site observations of the smoke pall associated with the 1998 Central American fires SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID RAMAN LIDAR MEASUREMENTS; OPTICAL-PROPERTIES; WATER-VAPOR; SIZE DISTRIBUTION; ATMOSPHERIC RADIATION; AEROSOL EXTINCTION; MICROPULSE LIDAR; FLOW PATTERNS; TRAJECTORIES; BRAZIL AB Drought-stricken areas of Central America and Mexico were victimized in 1998 by forest and brush fires that burned out of control during much of the first half of the year. Wind currents at various times during the episode helped transport smoke from these fires over the Gulf of Mexico and into portions of the United Slates. Visibilities were greatly reduced during favorable flow periods from New Mexico to south Florida and northward to Wisconsin as a result of this smoke and haze. In response to the reduced visibilities and increased pollutants, public health advisories and information statements were issued by various agencies in Gulf Coast states and in Oklahoma. This event was also detected by a unique array of instrumentation deployed at the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program Southern Great Plains Cloud and Radiation Testbed and by sensors of the Oklahoma Department of Environmental Quality/Air Quality Division. Observations from these measurement devices suggest elevated levels of aerosol loading and ozone concentrations during May 1998 when prevailing winds were favorable for the transport of the Central American smoke pall into Oklahoma and Kansas. In particular, aerosol extinction profiles derived from the ARM Raman lidar measurements revealed large variations in the vertical distribution of the smoke. C1 Cooperat Inst Mesoscale Meteorol Studies, Norman, OK 73019 USA. Pacific NW Natl Lab, Richland, WA USA. Sci Syst & Applicat Inc, Lanham, MD USA. Oak Ridge Natl Lab, Oak Ridge, TN USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. Brookhaven Natl Lab, Upton, NY 11973 USA. NASA, Langley Res Ctr, Sci Applicat Int Corp, Hampton, VA 23665 USA. Oak Ridge Associated Univ, Oak Ridge, TN USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. Univ N Dakota, Grand Forks, ND 58201 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Utah, Salt Lake City, UT USA. Univ Utah, Cooperat Inst Reg Predict, Salt Lake City, UT USA. RP Peppler, RA (reprint author), Cooperat Inst Mesoscale Meteorol Studies, 100 E Boyd St,Room 1110, Norman, OK 73019 USA. RI Campbell, James/C-4884-2012; Cheng, Meng-Dawn/C-1098-2012; Xiongfei, Zhao/G-7690-2015; Ogren, John/M-8255-2015; Lin, Che-Jen/K-1808-2013; OI Campbell, James/0000-0003-0251-4550; Ogren, John/0000-0002-7895-9583; Lin, Che-Jen/0000-0001-5990-3093; Splitt, Michael/0000-0002-7690-5100 NR 52 TC 51 Z9 52 U1 2 U2 3 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 NOV PY 2000 VL 81 IS 11 BP 2563 EP 2591 DI 10.1175/1520-0477(2000)081<2563:ASGPSO>2.3.CO;2 PG 29 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 370BB UT WOS:000165101300001 ER PT J AU Shukla, J Anderson, J Baumhefner, D Brankovic, C Chang, Y Kalnay, E Marx, L Palmer, T Paolino, D Ploshay, J Schubert, S Straus, D Suarez, M Tribbia, J AF Shukla, J Anderson, J Baumhefner, D Brankovic, C Chang, Y Kalnay, E Marx, L Palmer, T Paolino, D Ploshay, J Schubert, S Straus, D Suarez, M Tribbia, J TI Dynamical seasonal prediction SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID PREDICTABILITY; MODEL; SIMULATION; VARIABILITY; CIRCULATION; FORECASTS; ANOMALIES; PROJECT; ENSO AB Dynamical Seasonal Prediction (DSP) is an informally coordinated multi-institution research project to investigate the predictability of seasonal mean atmospheric circulation and rainfall. The basic idea is to test the feasibility of extending the technology of routine numerical weather prediction beyond the inherent limit of deterministic predictability of weather to produce numerical climate predictions using state-of-the-art global atmospheric models. Atmospheric general circulation models (AGCMs) either forced by predicted sea surface temperature (SST) or as part of a coupled forecast system have shown in the past that certain regions of the extratropics, in particular, the Pacific-North America (PNA) region during Northern Hemisphere winter, can be predicted with significant skill especially during years of large tropical SST anomalies. However, there is still a great deal of uncertainty about how much the details of various AGCMs impact conclusions about extratropical seasonal prediction and predictability. DSP is designed to compare seasonal simulation and prediction results from five state-of-the-art U.S. modeling groups (NCAR, COLA, GSFC, GFDL, NCEP) in order to assess which aspects of the results are robust and which are model dependent. The initial emphasis is on the predictability of seasonal anomalies over the PNA region. This paper also includes results from the ECMWF model, and historical forecast skill over both the PNA region and the European region is presented for all six models. It is found that with specified SST boundary conditions, all models show that the winter season mean circulation anomalies over the Pacific-North American region are highly predictable during years of large tropical sea surface temperature anomalies. The influence of large anomalous boundary conditions is so strong and so reproducible that the seasonal mean forecasts can be given with a high degree of confidence. However, the degree of reproducibility is highly variable from one model to the other, and quantities such as the PNA region signal to noise ratio are found to vary significantly between the different AGCMs. It would not be possible to make reliable estimates of predictability of the seasonal mean atmosphere circulation unless causes for such large differences among models are understood. C1 George Mason Univ, Ctr Ocean Land Atmosphere Studies, Calverton, MD 20705 USA. Geophys Fluid Dynam Lab, Princeton, NJ USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. European Ctr Medium Range Weather Forecasts, Reading RG2 9AX, Berks, England. Goddard Space Flight Ctr, Greenbelt, MD USA. Natl Ctr Environm Predict, Camp Springs, MD USA. RP Shukla, J (reprint author), George Mason Univ, Ctr Ocean Land Atmosphere Studies, 4041 Powder Mill Rd,Suite 302, Calverton, MD 20705 USA. RI Kalnay, Eugenia/F-4393-2010; OI Palmer, Tim/0000-0002-7121-2196; Kalnay, Eugenia/0000-0002-9984-9906 NR 30 TC 175 Z9 181 U1 1 U2 17 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 NOV PY 2000 VL 81 IS 11 BP 2593 EP 2606 DI 10.1175/1520-0477(2000)081<2593:DSP>2.3.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 370BB UT WOS:000165101300002 ER PT J AU Bess, TD Carlson, AB Mackey, C Denn, FM Wilber, A Ritchey, N AF Bess, TD Carlson, AB Mackey, C Denn, FM Wilber, A Ritchey, N TI World Wide Web access to radiation datasets for environmental and climate changes studies SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID BUDGET EXPERIMENT; INSTRUMENT; HISTORY AB Five years of scanner data from the Earth Radiation Budget Experiment (ERBE), eight years of surface radiation budget (SRB) data, and one year of scanner radiation budget data from the French-Russian-German experiment, ScaRaB, will be available for use by colleges and universities [and primary and secondary (K-12) schools] over a World Wide Web browser. The database for ERBE is a 5-yr monthly average time series from February 1985 through December 1989, and ScaRaB is a l-yr dataset from February 1994 to March 1995. ERBE and ScaRaB include shortwave radiative fluxes, emitted longwave radiative fluxes, and the earth's albedo measured at the top of the atmosphere. The SRB dataset spans the period from July 1983 through June 1991 and includes surface downward shortwave fluxes, surface downward longwave fluxes, surface albedos, and cloud percent. Students will have access to the data in three ways. They can display general image format images of any month and visually observe month-to-month or interannual variations. The data files for each month also have a spreadsheet format and can be downloaded in their entirety into any spreadsheet application program for further analysis. Third, using a live access server (LAS), students can interact directly with the data to select and subset datasets in terms of month, year, latitude, and longitude. The LAS allows students to view images of subsetted regions, and to subset data values to a file for further analysis. The server for this dataset is located at the National Aeronautics and Space Administration Langley Research Center, Hampton, Virginia. C1 NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. Analyt Serv & Mat Co, Hampton, VA USA. Comp Sci Corp, Hampton, VA USA. RP Bess, TD (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, MS-420, Hampton, VA 23681 USA. RI wilber, anne/F-6270-2011 NR 17 TC 2 Z9 2 U1 0 U2 1 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 NOV PY 2000 VL 81 IS 11 BP 2645 EP 2652 DI 10.1175/1520-0477(2000)081<2645:WWWATR>2.3.CO;2 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 370BB UT WOS:000165101300006 ER PT J AU Wright, R Rothery, DA Blake, S Pieri, DC AF Wright, R Rothery, DA Blake, S Pieri, DC TI Visualising active volcanism with high spatial resolution satellite data: the 1991-1993 eruption of Mount Etna SO BULLETIN OF VOLCANOLOGY LA English DT Article DE Mount Etna; 1991-1993 eruption; landsat TM; lava tubes ID LAVA FLOW-FIELD; THERMAL BUDGET; EFFUSION RATE; LANDSAT TM; MECHANISMS; VOLUME; TUBES; SHAPE AB We present seven Landsat Thematic Mapper (TM) images that document the period before, during and after the 1991-1993 eruption of Mount Etna. This episode remains the most volumetrically significant to occur at the volcano within the past 300 years. We show how TM data can be used to identify major changes in the lava flow regime, specifically the transition between channel and tube-fed now conditions, by mapping changes in the radiant properties of the flow surface. The high spatial resolution of TM (30-m pixels) allows point sources of radiance, such as skylights and tumuli, to be distinguished from linear radiant features such as surface lava flows. Using this information we illustrate the spatial and temporal development of a major tube system that developed within the flow-field. Detailed field maps of the tube system compiled by Calvari and Pinkerton (1998) allow us to validate the accuracy of our interpretations, and lead us to conclude that TM can be used to infer the position of tubes within the active flow-field to a reasonable level of accuracy. This indicates that similar high spatial resolution data could be used as a stand-alone tool to provide timely information regarding tube formation at future eruptions, useful information given that tubes can be a major factor in determining, for a given effusion rate, how far lava flows. When draped over a digital elevation model, the thermal data not only portray the nature of the relationship between flow surface structure and regional topography, but also provide a unique visualisation of how the flow-field advanced and threatened to inundate the town of Zafferana before, ultimately, being diverted. C1 Open Univ, Dept Earth Sci, Milton Keynes MK7 6AA, Bucks, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wright, R (reprint author), Univ Hawaii, Hawaii Inst Geophys & PLanetol, 2525 Correa Rd, Honolulu, HI 96822 USA. NR 31 TC 6 Z9 6 U1 0 U2 4 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0258-8900 J9 B VOLCANOL JI Bull. Volcanol. PD NOV PY 2000 VL 62 IS 4-5 BP 256 EP 265 DI 10.1007/s004450000104 PG 10 WC Geosciences, Multidisciplinary SC Geology GA 380AQ UT WOS:000165676500002 ER PT J AU Zak, M AF Zak, M TI Quantum model of emerging grammars SO CHAOS SOLITONS & FRACTALS LA English DT Article AB A special class of quantum recurrent nets (QRNs) simulating Markov chains with absorbing states is introduced. The absorbing states are exploited for pattern recognition: each class of patterns is attracted to a unique absorbing state. Due to quantum interference of patterns, each combination of patterns acquires its own meaning: it is attracted to a certain combination of absorbing states which is different from those of individual attractions. This fundamentally new effect can be interpreted as formation of a grammar, i.e., a set of rules assigning certain meaning to different combinations of patterns. It appears that there exists a class of unitary operators in which each member gives rise to a different artificial language with associated grammar. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Ultracomp Grp, Pasadena, CA 91109 USA. RP Zak, M (reprint author), CALTECH, Jet Prop Lab, Ultracomp Grp, Mail Stop 126-347, Pasadena, CA 91109 USA. NR 2 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0960-0779 J9 CHAOS SOLITON FRACT JI Chaos Solitons Fractals PD NOV PY 2000 VL 11 IS 14 BP 2325 EP 2330 DI 10.1016/S0960-0779(99)00153-8 PG 6 WC Mathematics, Interdisciplinary Applications; Physics, Multidisciplinary; Physics, Mathematical SC Mathematics; Physics GA 339QH UT WOS:000088489100016 ER PT J AU Jones, KH Olariu, S Rowell, LF Schwing, JL Wilhite, A AF Jones, KH Olariu, S Rowell, LF Schwing, JL Wilhite, A TI A database integrity monitor with applications to vehicular technology SO COMPUTER SYSTEMS SCIENCE AND ENGINEERING LA English DT Article DE integrity checking; databases; data engineering; mobility; management; cellular systems; EASIE AB One of the challenges facing the designers of an integrated engineering system is to blend in a robust and efficient way a wide variety of independently developed programs, each with its specific requirements for input and output. The Environment for Application Software Integration and Execution (EASIE, for short) provides a methodology and set of utility routines to support building, maintaining, and applying computer-aided design systems consisting of large numbers of diverse, stand-atone analysis codes. To support a high-productivity design and engineering environment, a tool is needed to identify potential integrity Violations introduced in the database as a result of activities involving manually changing the contents of some variables, and/or the subsequent execution of a number of analysis programs on the modified data. Such activities are routinely performed by design engineers in the aerospace industry, vehicular technology, and user mobility management in cellular systems. It is therefore important to create an environment that allows the designers to perform 'what if' experiments while, at the same time, monitoring the integrity of the underlying database. A fundamental task of such an environment is to make the user aware of potential integrity Violations introduced in the database as a result of any data changes. A trigger technique is described for identifying, beforehand, the set of all variables in the database susceptible to inconsistency. We offer a general solution to the integrity checking problem as defined above. Our integrity monitoring algorithms are transitive closure-based and they compare favorably with the state of the art both in simplicity and in efficiency. To illustrate, we show how our solution can be implemented in the Environment for Application Software integration and Execution (EASIE, for short) developed at NASA Langley Research Center (LaRC). We address this problem in general, and discuss how it can be implemented in EASIE. Our integrity monitoring algorithms are transitive closure-based and they compare favorably with the state of the art both in simplicity and in efficiency. C1 NASA, Langley Res Ctr, Anal & Computat Div, Hampton, VA 23665 USA. Old Dominion Univ, Dept Comp Sci, Norfolk, VA 23529 USA. NASA, Langley Res Ctr, Adv Vehicle Div, Hampton, VA USA. Cent Washington Univ, Dept Comp Sci, Ellensburg, WA 98926 USA. RP Jones, KH (reprint author), NASA, Langley Res Ctr, Anal & Computat Div, Hampton, VA 23665 USA. NR 20 TC 0 Z9 0 U1 0 U2 0 PU C R L PUBLISHING LTD PI MARKET HARBOROUG PA PO BOX 31, MARKET HARBOROUG LE16 9RQ, LEICS, ENGLAND SN 0267-6192 J9 COMPUT SYST SCI ENG JI Comput. Syst. Sci. Eng. PD NOV PY 2000 VL 15 IS 6 BP 405 EP 409 PG 5 WC Computer Science, Hardware & Architecture; Computer Science, Theory & Methods SC Computer Science GA 385HV UT WOS:000165998800004 ER PT J AU Kunz, RF Boger, DA Stinebring, DR Chyczewski, TS Lindau, JW Gibeling, HJ Venkateswaran, S Govindan, TR AF Kunz, RF Boger, DA Stinebring, DR Chyczewski, TS Lindau, JW Gibeling, HJ Venkateswaran, S Govindan, TR TI A preconditioned Navier-Stokes method for two-phase flows with application to cavitation prediction SO COMPUTERS & FLUIDS LA English DT Article DE Computational Fluid Dynamics (CFD); cavitation; multiphase AB An implicit algorithm for the computation of viscous two-phase flows is presented in this paper. The baseline differential equation system is the multi-phase Navier-Stokes equations, comprised of the mixture volume, mixture momentum and constituent volume fraction equations. Though further generalization is straightforward, a three-species formulation is pursued here, which separately accounts for the liquid and vapor (which exchange mass) as well as a non-condensable gas field. The implicit method developed here employs a dual-time, preconditioned, three-dimensional algorithm, with multiblock and parallel execution capabilities. Time-derivative preconditioning is employed to ensure well-conditioned eigenvalues, which is important for the computational efficiency of the method. Special care is taken to ensure that the resulting eigensystem is independent of the density ratio and the local volume fraction, which renders the scheme well-suited to high density ratio, phase-separated two-fluid flows characteristic of many cavitating and boiling systems. To demonstrate the capabilities of the scheme, several two- and three-dimensional examples are presented. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Penn State Univ, Appl Res Lab, University Pk, PA 16802 USA. Univ Tennessee, Inst Space, Tullahoma, TN 37388 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kunz, RF (reprint author), Penn State Univ, Appl Res Lab, University Pk, PA 16802 USA. NR 17 TC 282 Z9 343 U1 4 U2 54 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD NOV PY 2000 VL 29 IS 8 BP 849 EP 875 DI 10.1016/S0045-7930(99)00039-0 PG 27 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 346BU UT WOS:000088851200001 ER PT J AU Bui, TT AF Bui, TT TI A parallel, finite-volume algorithm for large-eddy simulation of turbulent flows SO COMPUTERS & FLUIDS LA English DT Article DE unstructured; parallel; finite-volume CFD algorithm; compressible ID NUMERICAL-SIMULATION; SQUARE DUCT; MODEL AB A parallel, finite-volume algorithm has been developed for large-eddy simulation (LES) of compressible turbulent flows. This algorithm includes piecewise linear least-square reconstruction, trilinear finite-element interpolation, Roe flux-difference splitting (FDS), and second-order MacCormack time marching. A systematic and consistent means of evaluating the surface and volume integrals of the control volume is described. Parallel implementation is done using the message-passing programming model, To validate the numerical method for turbulence simulation, LES of fully developed turbulent flow in a square duct is performed for a Reynolds number of 320 based on the average friction velocity and the hydraulic diameter of the duct. Direct numerical simulation (DNS) results are available for this test case, and the accuracy of this algorithm for turbulence simulations can be ascertained by comparing the LES solutions with the DNS results. For the first time, a finite volume method with Roe FDS was used for LES of turbulent flow in a square duct, and the effects of grid resolution, upwind numerical dissipation, and subgrid-scale dissipation on the accuracy of the LES are examined. Comparison with DNS results shows that the standard Roe FDS adversely affects the accuracy of the turbulence simulation. For accurate turbulence simulations, only 3-5% of the standard Roe FDS dissipation is needed. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Dryden Flight Res Ctr, Edwards, CA USA. RP Bui, TT (reprint author), NASA, Dryden Flight Res Ctr, Edwards, CA USA. NR 29 TC 27 Z9 30 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD NOV PY 2000 VL 29 IS 8 BP 877 EP 915 DI 10.1016/S0045-7930(99)00040-7 PG 39 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 346BU UT WOS:000088851200002 ER PT J AU Witham, CK Chun, W Valdez, TI Narayanan, SR AF Witham, CK Chun, W Valdez, TI Narayanan, SR TI Performance of direct methanol fuel cells with sputter-deposited anode catalyst layers SO ELECTROCHEMICAL AND SOLID STATE LETTERS LA English DT Article ID PT-RU ANODES; LOADING ELECTRODES; OXIDE FORMATION; OXIDATION; PLATINUM; REDUCTION AB Performance of direct methanol fuel cells with sputter-deposited Pt-Ru anodes was investigated. The thin film catalyst layers were characterized using X-ray diffraction, energy dispersive X-ray analysis, Rutherford backscattering spectroscopy, and X-ray photoelectron spectroscopy. Different catalyst loadings and membrane electrode assembly (MEA) fabrication processes were tested. The maximum power density achieved at 90 degrees C was 100 mW/cm(2), and almost 75 mW/cm(2) was attained with a loading of only 0.03 mg/cm(2). The results demonstrate that a catalyst utilization of at least 2300 mW/mg can be achieved at current densities ranging from 260 to 380 mA/cm(2). The application of the sputter-deposition method for MEA fabrication is particularly attractive for commercialization of direct methanol fuel cell technology. (C) 2000 The Electrochemical Society. S1099-0062(00)06-042-9. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Witham, CK (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 40 TC 97 Z9 99 U1 3 U2 16 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 65 SOUTH MAIN STREET, PENNINGTON, NJ 08534 USA SN 1099-0062 J9 ELECTROCHEM SOLID ST JI Electrochem. Solid State Lett. PD NOV PY 2000 VL 3 IS 11 BP 497 EP 500 PG 4 WC Electrochemistry; Materials Science, Multidisciplinary SC Electrochemistry; Materials Science GA 353MA UT WOS:000089277100002 ER PT J AU Seale, MD Madaras, EI AF Seale, MD Madaras, EI TI Transducer effects in ultrasonic measurements of material stiffness SO EXPERIMENTAL TECHNIQUES LA English DT Article C1 Thomas Nelson Community Coll, Hampton, VA 23670 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Seale, MD (reprint author), Thomas Nelson Community Coll, Hampton, VA 23670 USA. NR 8 TC 2 Z9 2 U1 0 U2 1 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0732-8818 J9 EXP TECHNIQUES JI Exp. Tech. PD NOV-DEC PY 2000 VL 24 IS 6 BP 35 EP 38 DI 10.1111/j.1747-1567.2000.tb01347.x PG 4 WC Engineering, Mechanical; Mechanics; Materials Science, Characterization & Testing SC Engineering; Mechanics; Materials Science GA 381QD UT WOS:000165773700006 ER PT J AU Mal, A Chang, ZS AF Mal, A Chang, ZS TI A semi-numerical method for elastic wave scattering calculations SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE finite elements; Lamb waves; scattering ID MULTIPLE-SCATTERING; LAMB WAVES; EDGE AB This paper is concerned with the calculation of elastic wavefields in strongly heterogeneous media containing scatterers of arbitrary shape and size. A hybrid method is described in which the elastodynamic field within a finite region enclosing the scatterers is modelled by finite elements while the field away from this region is represented by means of a suitable set of wave functions. Application of a variational principle and the continuity conditions at the interface between the two regions lead to a system of linear equations that is solved by standard techniques. The hybrid method extends the applicability of the finite element method to wave propagation problems in unbounded media by rigorously modelling the radiation field. The method is used to calculate the elastodynamic field in a plate of finite thickness and infinite lateral dimensions containing geometric discontinuities. C1 Univ Calif Los Angeles, Dept Mech & Aerosp Engn, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Univ Calif Los Angeles, Dept Mech & Aerosp Engn, Los Angeles, CA 90095 USA. EM ajit@ucla.edu NR 17 TC 16 Z9 16 U1 0 U2 2 PU OXFORD UNIV PRESS PI OXFORD PA GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND SN 0956-540X EI 1365-246X J9 GEOPHYS J INT JI Geophys. J. Int. PD NOV PY 2000 VL 143 IS 2 BP 328 EP 334 DI 10.1046/j.1365-246X.2000.01244.x PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 375KW UT WOS:000165399200007 ER PT J AU Rizi, V Masci, F Redaelli, G Di Carlo, P Iarlori, M Visconti, G Thomason, LW AF Rizi, V Masci, F Redaelli, G Di Carlo, P Iarlori, M Visconti, G Thomason, LW TI Lidar and SAGE II observations of Shishaldin volcano aerosols and lower stratospheric transport. SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NORTHERN AB During May 1999, data collected with two of University of L'Aquila lidar systems, Italy show an increase in the stratospheric aerosol content at altitudes between 15 and 18 km. Our initial hypothesis is that these aerosols originated from the Shishaldin (Alaska) volcanic eruption of 19 April 1999. SAGE IT observations, taken between Julian day 100 and 180, at latitudes above 40 degreesN, show several sightings that are good candidates for volcanic aerosols. A trajectory analysis shows that a few SAGE II. measurements are in space and time compatible with the Shishaldin eruption, and the aerosol enhancements observed by L'Aquila lidars have been also sampled by SAGE II, later and in different locations. C1 Univ Aquila, Dipartimento Fis, I-67010 Coppito, Italy. Ist Nazl Geofis, I-67100 Laquila, Italy. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Rizi, V (reprint author), Univ Aquila, Dipartimento Fis, Via Vetoio, I-67010 Coppito, Italy. RI Di Carlo, Piero/C-1657-2016; Di Carlo, Piero/Q-4450-2016; OI Di Carlo, Piero/0000-0003-4971-4509; Di Carlo, Piero/0000-0003-4971-4509; Redaelli, Gianluca/0000-0002-4449-1513; Thomason, Larry/0000-0002-1902-0840; Rizi, Vincenzo/0000-0002-5277-6527 NR 9 TC 4 Z9 4 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 2000 VL 27 IS 21 BP 3445 EP 3448 DI 10.1029/2000GL011515 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 369JW UT WOS:000165063000003 ER PT J AU Legresy, B Rignot, E Tabacco, IE AF Legresy, B Rignot, E Tabacco, IE TI Constraining ice dynamics at Dome C, Antarctica, using remotely sensed measurements SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID FLOW; INTERFEROMETRY AB A first time description is given of the ice flow at Dome C, Antarctica, around the EPICA drilling site. We used satellite radar altimetry to obtain the precise ice surface topography, airborne radio echo sounding to obtain the ice thickness and satellite SAR interferometry to derive one component of the surface velocity field. The balance flux around the Dome C area is then accurately mapped and comparisons made between driving stress, surface and balance velocity to help us describe the ice flow in the region. As a byproduct of the study, we also recover anomalies in the ice flow conditions in sub-glacial lake locations. These effects result from localy invalid shallow-ice approximation. The results of this study form the basis for future investigations of the ice flow conditions at Dome C in relation to ice core interpretation. C1 LEGOS, CNRS, CNES, UPS, F-31401 Toulouse 4, France. NASA, JPL, Pasadena, CA USA. DST Geophys, Milan, Italy. RP Legresy, B (reprint author), LEGOS, CNRS, CNES, UPS, 18 Av E Belin, F-31401 Toulouse 4, France. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 14 TC 7 Z9 7 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 2000 VL 27 IS 21 BP 3493 EP 3496 DI 10.1029/2000GL011707 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 369JW UT WOS:000165063000016 ER PT J AU Prabhakara, C Iacovazzi, R Yoo, JM Dalu, G AF Prabhakara, C Iacovazzi, R Yoo, JM Dalu, G TI Global warming: Evidence from satellite observations SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TEMPERATURE TIME-SERIES; SURFACE AIR-TEMPERATURE; MICROWAVE SOUNDING UNIT; MERGING PROCEDURE; TRENDS; MSU; RECORDS AB Observations made in Channel 2 (53.74 GHz) of the Microwave Sounding Unit (MSU) radiometer, flown onboard sequential, sun-synchronous, polar-orbiting NOAA operational satellites, indicate that the mean temperature of the atmosphere over the globe increased during the period 1980 to 1999. In this study, we have minimized systematic errors in the time series introduced by satellite orbital drift in an objective manner. This is done with the help of the onboard warm-blackbody temperature, which is used in the calibration of the MSU radiometer. The corrected MSU Channel 2 observations of the NOAA satellite series reveal that the vertically-weighted global-mean temperature of the atmosphere, with a peak weight near the mid troposphere, warmed at the rate of 0.13+/-0.05 Kdecade(-1) during 1980 to 1999. The global warming deduced from conventional meteorological data that have been corrected for urbanization effects agrees reasonably with this satellite-deduced result. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon ITSS, Lanham, MD USA. Ewha Womans Univ, Seoul, South Korea. CNR, Cagliari, Italy. RP NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. EM cuddapah@climate.gsfc.nasa.gov RI Iacovazzi Jr, Robert/G-3867-2010 NR 17 TC 27 Z9 28 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 EI 1944-8007 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 2000 VL 27 IS 21 BP 3517 EP 3520 DI 10.1029/2000GL011719 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 369JW UT WOS:000165063000022 ER PT J AU Sherwood, SC AF Sherwood, SC TI Climate signal mapping and an application to atmospheric tides SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB When analyzing irregularly sampled data to obtain climate signals, a typical starting point is to use spatial analysis methods to map observations onto a regular grid. Clear benefits are possible, however, from an alternative approach in which the desired signals are first estimated directly at the observing locations. The most important benefits relate to accuracy and error analysis. These principles are illustrated using the example of atmospheric tides. When properly estimated, the tides agree remarkably well with those simulated by the Goddard Earth Observing System general circulation model and, above the tropopause, are comparable to the mean meridional flow. C1 Univ Space Res Assoc, Seabrook, MD USA. RP Sherwood, SC (reprint author), NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA. RI Sherwood, Steven/B-5673-2008 OI Sherwood, Steven/0000-0001-7420-8216 NR 11 TC 8 Z9 8 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 2000 VL 27 IS 21 BP 3525 EP 3528 DI 10.1029/2000GL011424 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 369JW UT WOS:000165063000024 ER PT J AU Dohm, JM Anderson, RC Baker, VR Ferris, JC Hare, TM Strom, RG Rudd, LP Rice, JW Casavant, RR Scott, DH AF Dohm, JM Anderson, RC Baker, VR Ferris, JC Hare, TM Strom, RG Rudd, LP Rice, JW Casavant, RR Scott, DH TI System of gigantic valleys northwest of Tharsis, Mars: latent catastrophic flooding, northwest watershed, and implications for northern plains ocean SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MARTIAN OUTFLOW CHANNELS; ANCIENT OCEANS; GEOLOGY AB Mars Orbiter Laser Altimeter (MOLA) reveals a system of gigantic valleys to the northwest of the huge martian shield volcano, Arsia Mons, in the western hemisphere of Mars. These newly identified northwestern slope valleys (NSVs) potentially signify previously undocumented martian catastrophic floods and may corroborate the northern ocean hypotheses. These features, which generally correspond spatially to gravity lows, were previously obscured in Mariner and Viking Orbiter imagery by veneers of materials, including volcanic lava flows and air fall deposits. Geologic investigations of the Tharsis region suggest that the NSVs were mainly carved prior to the construction of Arsia Mons and its associated Late Hesperian and Amazonian age lava flows, concurrent with the early development of the outflow channels that debouch into Chryse Planitia. C1 Univ Arizona, Dept Hydrol & Water Resources, Tucson, AZ 85721 USA. Jet Prop Lab, Pasadena, CA USA. US Geol Survey, Flagstaff, AZ USA. RP Dohm, JM (reprint author), Univ Arizona, Dept Hydrol & Water Resources, Tucson, AZ 85721 USA. RI Dohm, James/A-3831-2014; OI Hare, Trent/0000-0001-8842-389X NR 33 TC 14 Z9 15 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 2000 VL 27 IS 21 BP 3559 EP 3562 DI 10.1029/2000GL011728 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 369JW UT WOS:000165063000033 ER PT J AU Cane, HV Richardson, IG Cyr, OCS AF Cane, HV Richardson, IG Cyr, OCS TI Coronal mass ejections, interplanetary ejecta and geomagnetic storms SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETIC CLOUDS; SHOCKS AB Studies using SOHO spacecraft data have demonstrated that frontside halo coronal mass ejections (CMEs) detected by the LASCO coronagraphs generally precede geomagnetic storms. Nonetheless, about three quarters of such CMEs do not result in even moderate geomagnetic activity. We study the relationship of all the ejecta (interplanetary CMEs) which passed Earth during 1996-1999 to coronagraph CMEs and geomagnetic activity. We reach the following conclusions: (1) Only about half of frontside halo CMEs encounter the Earth; (2) The geoeffectiveness of ejecta depends strongly on the southward magnetic field strength and, for the same southward field, is irrespective of whether or not the ejecta has a magnetic cloud structure; (3) Transit speeds of ejecta to Earth are only loosely correlated with CME speeds, one influence being the prevailing solar wind conditions between the Sun and Earth; (4) Ejecta may be detected at Earth even when there is no preceding halo CME observed by LASCO. Such ejecta are not particularly geoeffective. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Computat Phys Inc, Greenbelt, MD 20771 USA. Univ Tasmania, Sch Math & Phys, Hobart, Tas, Australia. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. Catholic Univ Amer, Washington, DC 20064 USA. RP Cane, HV (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. OI Richardson, Ian/0000-0002-3855-3634 NR 13 TC 129 Z9 133 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD NOV 1 PY 2000 VL 27 IS 21 BP 3591 EP 3594 DI 10.1029/2000GL000111 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 369JW UT WOS:000165063000041 ER PT J AU Wilson, JW AF Wilson, JW TI Overview of radiation environments and human exposures SO HEALTH PHYSICS LA English DT Review DE National Council on Radiation Protection and; Measurements; exposure, occupational; radiation, cosmic; health effects ID GALACTIC COSMIC-RADIATION; MUTATION-INDUCTION; SPACE RADIATION; HEAVY-IONS; BIOLOGICAL EFFECTIVENESS; COMMERCIAL AVIATION; EARTHS ATMOSPHERE; ALPHA-PARTICLES; MAMMALIAN-CELLS; TRACK STRUCTURE AB Human exposures to ionizing radiation have been vastly altered by developing technology in the last century. This has been most obvious in the development of radiation generating devices and the utilization of nuclear energy. But even air travel has had its impact on human exposure. Human exposure increases with advancing aircraft technology as a result of the higher operating altitudes reducing the protective cover provided by Earth's atmosphere from extraterrestrial radiations. This increase in operating altitudes is taken to a limit by human operations in space. Less obvious is the changing character of the radiations at higher altitudes. The associated health risks are less understood with increasing altitude due to the increasing complexity and new field components found in high-altitude and space operations. C1 NASA, Environm Interact Branch, Div Mat, Langley Res Ctr, Hampton, VA 23681 USA. EM john.w.wilson@larc.nasa.com RI huang, hongqi/N-1473-2014 NR 111 TC 46 Z9 48 U1 1 U2 4 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0017-9078 EI 1538-5159 J9 HEALTH PHYS JI Health Phys. PD NOV PY 2000 VL 79 IS 5 BP 470 EP 494 DI 10.1097/00004032-200011000-00005 PG 25 WC Environmental Sciences; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging SC Environmental Sciences & Ecology; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging GA 364LD UT WOS:000089893100005 PM 11045522 ER PT J AU Badhwar, GD AF Badhwar, GD TI Radiation measurements in low Earth orbit: US and Russian results SO HEALTH PHYSICS LA English DT Article DE National Council on Radiation Protection and; Measurements; exposure, occupational; radiation, cosmic; dosimetry ID SPACE AB The radiation environment in low-Earth orbital flights is complex. It is strongly influenced by altitude, orbital inclination, time within a given solar cycle, flight duration, and shielding configuration. At any specified shielded location, both primary and secondary particles generated by nuclear interactions of primary particles with spacecraft structure are present. In addition, there are atmospheric secondary albedo protons and neutrons. No single detector can adequately measure this complex radiation field, and measurements of very high linear energy transfer target fragmentation products are particularly difficult. Crew radiation exposure have exclusively been measured using passive thermoluminescent detectors (TLDs). The cosmonaut exposures on the Mir station, uncorrected for the TLD inefficiency and neutron contribution, have varied from a low of 2.43 cGy to a high of 8.70 cGy. These correspond to dose rates of 144 mu Gy d(-1) to 468 mu Gy d(-1). These are consistent with rates observed by the D2 ion-chamber. Using the rates measured by the D1 chamber, dose rates under 4 cm of water vary from about 60 mu Gy d(-1) to about 350 mu Gy d(-1). There is variation of about a factor of two between the dose rates at various locations in the same module. There is also a variation of dose rates of about a factor two between various modules. The highest astronaut dose for a Shuttle flight (STS-82) was 3.205 cGy with a dose rate of 3,221 mu Gy d(-1). Neutron contribution could be 36 +/- 15% of the astronaut charged particle dose equivalent. East-West asymmetry of dose rate is significant for spacecrafts that fly in an fixed altitude, such as the International Space Station. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 3 TC 18 Z9 19 U1 0 U2 3 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0017-9078 EI 1538-5159 J9 HEALTH PHYS JI Health Phys. PD NOV PY 2000 VL 79 IS 5 BP 507 EP 514 DI 10.1097/00004032-200011000-00007 PG 8 WC Environmental Sciences; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging SC Environmental Sciences & Ecology; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging GA 364LD UT WOS:000089893100007 PM 11045524 ER PT J AU Simonsen, LC Wilson, JW Kim, MH Cucinotta, FA AF Simonsen, LC Wilson, JW Kim, MH Cucinotta, FA TI Radiation exposure for human Mars exploration SO HEALTH PHYSICS LA English DT Article DE National Council on Radiation Protection and; Measurements; exposure, occupational; radiation, cosmic; health effects ID GALACTIC COSMIC-RAYS; SPACE; MODEL; PROTECTION AB One major obstacle to human space exploration is the possible limitations imposed by the adverse effects of long-term exposure to the space environment. Even before human space flight began, the potentially brief exposure of astronauts to the very intense random solar energetic particle events was of great concern. A new challenge appears in deep-space exploration from exposure to the low-intensity heavy-ion flux of the galactic cosmic rays since the missions are of long duration, and accumulated exposures can be high. Because cancer induction rates increase behind low to moderate thicknesses of aluminum shielding, according to available biological data on mammalian exposures to galactic cosmic ray-like ions, aluminum shield requirements for a Mars mission may be prohibitively expensive in terms of mission launch costs. Alternative materials for vehicle construction are under investigation to provide lightweight habitat structures with enhanced shielding properties. In the present paper, updated estimates for astronaut exposures on a Mars mission are presented and shielding properties of alternative materials are compared with aluminum. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RI huang, hongqi/N-1473-2014 NR 33 TC 44 Z9 45 U1 5 U2 8 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0017-9078 EI 1538-5159 J9 HEALTH PHYS JI Health Phys. PD NOV PY 2000 VL 79 IS 5 BP 515 EP 525 DI 10.1097/00004032-200011000-00008 PG 11 WC Environmental Sciences; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging SC Environmental Sciences & Ecology; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging GA 364LD UT WOS:000089893100008 PM 11045525 ER PT J AU Rubincam, DP AF Rubincam, DP TI Radiative spin-up and spin-down of small asteroids SO ICARUS LA English DT Article; Proceedings Paper CT 7th International Asteroids, Comets, Meteors Conference (ACM 99) CY JUL 26-30, 1999 CL CORNELL UNIV, ITHACA, NEW YORK HO CORNELL UNIV DE asteroids; rotation; meteoroids; asteroids; Eros; asteroids; Gaspra; surfaces, Asteroid ID EARTH; SHAPE; DISRUPTION; SPACECRAFT; EVOLUTION; TOUTATIS; PHOBOS; FLYBY; EROS AB The Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect may spin up or spin down 5-km-radius asteroids on a 10(8)-year timescale. Smaller asteroids spin up or down even faster due to the radius-squared dependence of the YORP timescale. The mechanism is the absorption of sunlight and its re-emission as thermal radiation from an irregularly shaped asteroid. This effect may compete with impacts and tidal encounters as a way of changing rotation rates for small asteroids, especially in the near-Earth region. The YORP effect may explain the rapid rotation of 1566 Icarus and the slow tumbling of 4179 Toutatis. It may explain to some extent the slow rotation of 253 Mathilde. Meteoroids spin up or down on timescales fast compared to their cosmic ray exposure ages. C1 NASA, Goddard Space Flight Ctr, Terr Phys Lab, Geodynam Branch, Greenbelt, MD 20771 USA. RP Rubincam, DP (reprint author), NASA, Goddard Space Flight Ctr, Terr Phys Lab, Geodynam Branch, Code 921, Greenbelt, MD 20771 USA. RI Rubincam, David/D-2918-2012 NR 38 TC 262 Z9 262 U1 4 U2 13 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2000 VL 148 IS 1 BP 2 EP 11 DI 10.1006/icar.2000.6485 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375UV UT WOS:000165420400002 ER PT J AU Pravec, P Harris, AW AF Pravec, P Harris, AW TI Fast and slow rotation of asteroids SO ICARUS LA English DT Article; Proceedings Paper CT 7th International Asteroids, Comets, Meteors Conference (ACM 99) CY JUL 26-30, 1999 CL CORNELL UNIV, ITHACA, NEW YORK HO CORNELL UNIV DE asteroids, rotations; structure, rubble pile; objects, near-Earth ID SPIN; EVOLUTION; RATES AB We present an analysis of the distribution of asteroid spin rates vs. size. The existence of significant populations of both slow and fast rotators among asteroids smaller than D = 40 km, and especially below 10 km (where our sample is mostly near-Earth asteroids), is shown. We have found that the excess of slow rotators is present at spin rates below approximate to0.8 rev/day, and the group of fast rotators occupies the range of spin rates >7 rev/day. The fast rotators show interesting characteristics: The lack of objects rotating faster than 2.2 h period among asteroids with absolute magnitude H < 22, as well as the tendency to spheroidal shapes of fast rotators, is evidence that asteroids larger than a few hundred meters are mostly loosely bound, gravity-dominated aggregates with negligible tensile strength ("rubble piles"), while monoliths may be abundant among smaller objects. A large fraction (about half) of near-Earth fast-rotating asteroids appear to be binary systems, probably created by tidal disruptions during close encounters with the terrestrial planets. (C) 2000 Academic Press. C1 Acad Sci Czech Republ, Inst Astron, CZ-25165 Ondrejov, Czech Republic. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Pravec, P (reprint author), Acad Sci Czech Republ, Inst Astron, CZ-25165 Ondrejov, Czech Republic. RI Pravec, Petr/G-9037-2014 NR 31 TC 161 Z9 161 U1 0 U2 3 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2000 VL 148 IS 1 BP 12 EP 20 DI 10.1006/icar.2000.6482 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375UV UT WOS:000165420400003 ER PT J AU McCoy, TJ Nittler, LR Burbine, TH Trombka, JI Clark, PE Murphy, ME AF McCoy, TJ Nittler, LR Burbine, TH Trombka, JI Clark, PE Murphy, ME TI Anatomy of a partially differentiated asteroid: A "NEAR"-sighted view of acapulcoites and lodranites SO ICARUS LA English DT Article; Proceedings Paper CT 7th International Asteroids, Comets, Meteors Conference (ACM 99) CY JUL 26-30, 1999 CL CORNELL UNIV, ITHACA, NY HO CORNELL UNIV DE asteroids; asteroids, Eros; asteroids, composition; meteorites; NEAR mission ID ORDINARY CHONDRITES; IRON-METEORITES; PARENT BODY; DIFFUSION AB With the insertion of the NEAR spacecraft into orbit around the asteroid 433 Eros, a new stage of asteroid exploration has begun, with the return of spatially resolved mineralogical, geological, and chemical information from specific asteroids. In this paper, we outline the features of a partially differentiated asteroid using the acapulcoite and lodranite meteorites as a guide. Such a body would likely contain a variety of lithologies, including chondritic rocks largely unaltered by melting, residues of partial melts, and basaltic and Fe,Ni-FeS rocks crystallized from the partial melts. The presence or nature of the regolith remains largely unconstrained, Mineralogical and isotopic heterogeneities preserved in these rocks suggest spatial separation of these rock types by distances in excess of 200 m. Spacecraft-based remote sensing instrumentation should detect substantial spectral heterogeneity (most prominently manifested in the band area ratio) and chemical heterogeneity. Observation of these various lithologies in situ would provide important new constraints on the processes involved during the earliest differentiation of asteroids. C1 Smithsonian Inst, Dept Mineral Sci, Museum Natl Hist Nat, Washington, DC 20560 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP McCoy, TJ (reprint author), Smithsonian Inst, Dept Mineral Sci, Museum Natl Hist Nat, Washington, DC 20560 USA. NR 30 TC 17 Z9 17 U1 0 U2 1 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2000 VL 148 IS 1 BP 29 EP 36 DI 10.1006/icar.2000.6494 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375UV UT WOS:000165420400005 ER PT J AU Hudson, RS Ostro, SJ Jurgens, RF Rosema, KD Giorgini, JD Winkler, R Rose, R Choate, D Cormier, RA Franck, CR Frye, R Howard, D Kelley, D Littlefair, R Slade, MA Benner, LAM Thomas, ML Mitchell, DL Chodas, PW Yeomans, DK Scheeres, DJ Palmer, P Zaitsev, A Koyama, Y Nakamura, A Harris, AW Meshkov, MN AF Hudson, RS Ostro, SJ Jurgens, RF Rosema, KD Giorgini, JD Winkler, R Rose, R Choate, D Cormier, RA Franck, CR Frye, R Howard, D Kelley, D Littlefair, R Slade, MA Benner, LAM Thomas, ML Mitchell, DL Chodas, PW Yeomans, DK Scheeres, DJ Palmer, P Zaitsev, A Koyama, Y Nakamura, A Harris, AW Meshkov, MN TI Radar observations and physical model of asteroid 6489 Golevka SO ICARUS LA English DT Article; Proceedings Paper CT 7th International Asteroids, Comets, Meteors Conference (ACM 99) CY JUL 26-30, 1999 CL CORNELL UNIV, ITHACA, NY HO CORNELL UNIV DE asteroids; radar ID NEAR-EARTH ASTEROIDS; 6489-GOLEVKA 1991-JX; TOUTATIS; ORBITS; SPECTRA AB We report 8510-MHz (3,5-cm) radar observations of the Earth-crossing asteroid (ECA) 6489 Golevka (1991 JX) obtained between June 3 and June 15, 1995, at Goldstone, the Very Large Array and the Evpatoria (Ukraine) and Kashima (Japan) radio antennas. One-dimensional Doppler spectra are used to estimate the object's convex hull, refine the ephemeris, and yield four possible pole directions. Three-dimensional modeling using two-dimensional delay-Doppler images and published lightcurves unambiguously defines the pole and reveals an extraordinarily angular shape with flat sides, sharp edges and corners, and peculiar concavities. The equivalent diameter of the object is 530 +/- 30 m, with moments of inertia about the (long, intermediate, short) axes proportional to (1.00, 1,38, 1.39) +/- 0.1. The asteroid's pole direction is lambda = 202 +/- 5 degrees, beta = -45 +/- 5 degrees, and its sidereal period is P = 6.0289 +/- 0.0001 h, The asteroid's circular polarization ratio, SC/OC = 0.23 +/- 0,02, is lower than the average for radar-detected near-Earth asteroids and reveals only a modest degree of near-surface roughness at scales near the 3.5-cm wavelength. However, the approximately Lambertian radar scattering law implies considerable surface roughness at larger scales. The asteroid's radar scattering law is modeled as rho cos(n) theta, with rho = 0.25 +/- 0.12 and n = 1.7 +/- 0.7 giving an equivalent spherical albedo of 0.18 +/- 0.09. This value is in the middle of the distribution of albedos of S-class asteroid's previously imaged by radar. The Hapke parameters describing the object's optical scattering properties are w = 0.173 +/- 0.006, h = 0.024 +/- 0.012, B(0) = 1.03 +/- 0.45, g = -0.34 +/- 0.02, and <()over bar> = 20 +/- 5 degrees. Both the optical and the radar scattering properties are consistent with those of a typical S-class asteroid. Goldstone-VLA plane-of-sky images do not resolve the asteroid but do provide astrometry with uncertainties less than 0.1 arcsec. Integration of an orbit based on all available radar and optical astrometry shows that Golevka has an insignificant probability of collision with any planet during at least the next nine centuries. We investigate Golevka's dynamical environment, assuming uniform density. Some areas of the surface are characterized by large enough slopes that we expect that they are exposed, solid, monolithic rock, (C) 2000 Academic Press. C1 Washington State Univ, Sch Elect Engn & Comp Sci, Pullman, WA 99164 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Michigan, Dept Aerosp Engn, Ann Arbor, MI 48109 USA. Univ Chicago, Ctr Astron & Astrophys, Chicago, IL 60637 USA. Inst Radioengn & Elect, Moscow 141120, Russia. Kashima Space Res Ctr, Commun Res Lab, Kashima, Ibaraki 314, Japan. DLR, Inst Space Sensor Technol & Planetary Explorat, D-12489 Berlin, Germany. Moscow Energy Inst, Special Design Off, Moscow 111250, Russia. RP Hudson, RS (reprint author), Washington State Univ, Sch Elect Engn & Comp Sci, Pullman, WA 99164 USA. EM hudson@eecs.wsu.edu RI Nakamura, Akiko/I-1993-2012 OI Nakamura, Akiko/0000-0001-6990-8496 NR 32 TC 42 Z9 44 U1 0 U2 1 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2000 VL 148 IS 1 BP 37 EP 51 DI 10.1006/icar.2000.6483 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375UV UT WOS:000165420400006 ER PT J AU Evans, LG Starr, R Trombka, JI McClanahan, TP Bailey, SH Mikheeva, I Bhangoo, J Bruckner, J Goldsten, JO AF Evans, LG Starr, R Trombka, JI McClanahan, TP Bailey, SH Mikheeva, I Bhangoo, J Bruckner, J Goldsten, JO TI Calibration of the NEAR gamma-ray spectrometer SO ICARUS LA English DT Article DE asteroids; instrumentation; gamma rays; geochemistry; NEAR mission ID ASTEROID RENDEZVOUS MISSION; X-RAY; DETECTORS AB The gamma-ray spectrometer onboard the Near Earth Asteroid Rendezvous spacecraft will measure gamma rays from the surface of 433 Eros in the 100-keV to 10-MeV energy region. Detection of characteristic gamma-ray emissions from such elements as O, Si, Fe, Ca, Ti, Mg, Al, H, K, Th, and U will allow the determination of abundances of these geologically important elements. Spatial resolution will be large, but the emission detected will originate from a volume of material down to depths of 10-20 cm below the surface. These measurements will make it possible to relate Eros to known meteorite classes and to relate these to geological processes on Eros. The calibration measurements and analysis procedures that are described will be needed for the reduction and analysis of gamma-ray data collected during the mission. In addition to geochemical measurements, the gamma-ray detector is used to detect gamma-ray bursts and forms part of the interplanetary network of gamma-ray detectors used to determine the source positions of gamma-ray bursts. (C) Academic Press. C1 Comp Sci Corp, Lanham, MD 20706 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Max Planck Inst Chem, D-55128 Mainz, Germany. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. RP Evans, LG (reprint author), Comp Sci Corp, Lanham, MD 20706 USA. EM larry.evans@gsfc.nasa.gov NR 27 TC 8 Z9 8 U1 0 U2 1 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2000 VL 148 IS 1 BP 95 EP 117 DI 10.1006/icar.2000.6461 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375UV UT WOS:000165420400010 ER PT J AU Vokrouhlicky, D Milani, A Chesley, SR AF Vokrouhlicky, D Milani, A Chesley, SR TI Yarkovsky effect on small near-earth asteroids: Mathematical formulation and examples SO ICARUS LA English DT Article DE asteroids; Yarkovsky effect; orbit determination ID RADAR OBSERVATIONS; 6489-GOLEVKA 1991-JX; FRAGMENTS; MODEL; MOBILITY; 1620-GEOGRAPHOS; LIGHTCURVES; METEORITES; DELIVERY; ICARUS AB The Yarkovsky effect is a subtle nongravitational phenomenon related to the anisotropic thermal emission of Solar System objects. Its importance has been recently demonstrated in relation to the transport of material from the main asteroid belt (both to explain the origin of near-Earth asteroids and some properties of meteorites) and also in relation to the aging processes of the asteroid families. However, unlike the case of the artificial satellites, the Yarkovsky effect has never been measured or detected in the motion of natural bodies in the Solar System. In this paper, we investigate the possibility of detecting the Yarkovsky effect via precise orbit determination of near-Earth asteroids. Such a detection is feasible only with the existence of precise radar astrometry at multiple apparitions. Since the observability of the Yarkovsky perturbation accumulates quadratically with time the time span between radar observations is a critical factor. Though the current data do not clearly indicate the Yarkovsky effect in the motion of these bodies, we predict that the next apparition of several asteroids tin particular, 6489 Golevka, 1620 Geographos, and possibly 1566 Icarus) might reveal its existence. Moreover, we show that the Yarkovsky effect may play a very important role in the orbit determination of small, but still observable, bodies like 1998 KY26. If carefully followed, this body may serve as a superb probe of the Yarkovsky effect in its next close approach to the Earth in June 2024. (C) 2000 Academic Press. C1 Charles Univ, Astron Inst, CZ-18000 Prague 8, Czech Republic. Univ Pisa, Dipartimento Matemat, I-56127 Pisa, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Vokrouhlicky, D (reprint author), Charles Univ, Astron Inst, V Holesovickach 2, CZ-18000 Prague 8, Czech Republic. NR 52 TC 60 Z9 60 U1 1 U2 2 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2000 VL 148 IS 1 BP 118 EP 138 DI 10.1006/icar.2000.6469 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375UV UT WOS:000165420400011 ER PT J AU Davies, AG Lopes-Gautier, R Smythe, WD Carlson, RW AF Davies, AG Lopes-Gautier, R Smythe, WD Carlson, RW TI Silicate cooling model fits to Galileo NIMS data of volcanism on Io SO ICARUS LA English DT Article DE Io; volcanism; thermal; modeling ID INFRARED MAPPING SPECTROMETER; THERMAL EMISSION; LAVA FLOWS; HOT-SPOTS; ACTIVE VOLCANISM; SULFUR FLOWS; TEMPERATURE; ERUPTIONS; SSI; VOYAGER-1 AB The Near Infrared Mapping Spectrometer (NIMS) has obtained spectra of volcanoes on the surface of the jovian satellite Io. Fits to data using a silicate cooling model allow us to constrain lava eruption rates and eruption age. The thermal signatures of the hot spots are indicative of active and cooling silicate lava flows. For large, active hot spots maximum ages of how surfaces detected by NIMS typically range from days to months, although in one case it is nearly 30 years. Mass eruption rates for the main hot spots are in the range 7 m(3) s(-1) to 79 m(3) s(-1), using an average how thickness of 1 m. These mass eruption rates are orders of magnitude less than those implied for large thermal outbursts on Io: the eruptions observed during June 1996 are most likely of a different eruption style, on a much smaller scale. The observation analyzed here may he representative of the current background level of volcanic activity on the anti-jove hemisphere of Io. The global mass eruption rate from these "non-outburst" hot spots is calculated to be 43 km(3)/year, equivalent to a global resurfacing rate of about 1 mm/year, about 10% of the minimum required global resurfacing volume. The total observed energy output from the 14 hot spots analyzed is 3.6 x 10(12) W. Normalized globally, these hot spots contribute approximately 10% of Io's radiometric heat flux. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Davies, AG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Lopes, Rosaly/D-1608-2016 OI Lopes, Rosaly/0000-0002-7928-3167 NR 50 TC 24 Z9 24 U1 0 U2 0 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2000 VL 148 IS 1 BP 211 EP 225 DI 10.1006/icar.2000.6486 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375UV UT WOS:000165420400018 ER PT J AU Baines, KH Bellucci, G Bibring, JP Brown, RH Buratti, BJ Bussoletti, E Capaccioni, F Cerroni, P Clark, RN Coradini, A Cruikshank, DP Drossart, P Formisano, V Jaumann, R Langevin, Y Matson, DL McCord, TB Mennella, V Nelson, RM Nicholson, PD Sicardy, B Sotin, C Hansen, GB Aiello, JJ Amici, S AF Baines, KH Bellucci, G Bibring, JP Brown, RH Buratti, BJ Bussoletti, E Capaccioni, F Cerroni, P Clark, RN Coradini, A Cruikshank, DP Drossart, P Formisano, V Jaumann, R Langevin, Y Matson, DL McCord, TB Mennella, V Nelson, RM Nicholson, PD Sicardy, B Sotin, C Hansen, GB Aiello, JJ Amici, S TI Detection of sub-micron radiation from the surface of venus by Cassini/VIMS SO ICARUS LA English DT Article DE Venus; spectrophotometry; surfaces; Planets; Venus; surface; minerology ID INFRARED MAPPING SPECTROMETER; NIGHT-SIDE; DEEP ATMOSPHERE; CARBON-MONOXIDE; CLOUD STRUCTURE; DARK SIDE; GALILEO; SPECTRA; ABUNDANCE; FEATURES AB We report the first detection and profile characterization of thermal emission from the surface of Venus at 0.85 and 0.90 mum, observed in the first planetary spectrum acquired by the Visual-Infrared Mapping Spectrometer onboard the Cassini spacecraft en route to the Saturn system. The strength and shape of these two newly observed nightside emissions agree with theoretical predictions based on the strength of the strong emission observed at 1.01 mum, These emissions, together with previously-reported surface emission features at 1,01, 1,10, and 1.18 mum, potentially provide a new technique for remotely mapping the mineralogical composition of the venusian surface. (C) 2000 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Area Ric Tor Vergatia, Ist Fis Spazio Interplanetario, I-00198 Rome, Italy. IAS, F-91405 Orsay, France. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Univ Naples, Ist Navale, I-80138 Naples, Italy. Area Ric Tor Vergatia, Ist Astrofis Spaziale, I-00133 Rome, Italy. US Geol Survey, Lakewood, CO 80225 USA. Area Ric Tor Vergatia, Ist Astrofis Spaziale, I-00198 Rome, Italy. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Observ Paris, DESPA, CNRS, UMR 8632, F-92195 Meudon, France. DLR, Inst Space Sensor Technol & Planetary Explorat, D-12489 Berlin, Germany. IAS, F-91405 Orsay, France. Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Osservatorio Astron Capodimonte, I-80131 Naples, Italy. Cornell Univ, Dept Astron, Ithaca, NY 14853 USA. Observ Paris Meudon, F-92195 Meudon, France. Univ Paris, F-92195 Meudon, France. Univ Nantes, Lab Planetol & Geodynam, F-44322 Nantes 3, France. Univ Hawaii, Dept Geophys & Planetol, Honolulu, HI 96822 USA. RP Baines, KH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 183-601, Pasadena, CA 91109 USA. OI Cerroni, Priscilla/0000-0003-0239-2741; Bellucci, Giancarlo/0000-0003-0867-8679; Capaccioni, Fabrizio/0000-0003-1631-4314 NR 29 TC 38 Z9 39 U1 0 U2 3 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD NOV PY 2000 VL 148 IS 1 BP 307 EP 311 DI 10.1006/icar.2000.6519 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 375UV UT WOS:000165420400023 ER PT J AU Pogorzelski, RJ AF Pogorzelski, RJ TI A two-dimensional coupled oscillator array SO IEEE MICROWAVE AND GUIDED WAVE LETTERS LA English DT Article DE injection locking; phased arrays; voltage controlled oscillators AB Design, fabrication, and test of a two-dimensional (2-D)coupled oscillator array is described. The array consists of nine voltage-controlled oscillators in a 3 x 3 configuration and operates at S-band. It is demonstrated experimentally that the array can generate planar phase distributions suitable for producing a radiated beam which is agile in two dimensions via tuning of the perimeter oscillators only. This is believed to be the first implementation of such an array. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Pogorzelski, RJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 4 TC 18 Z9 19 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1051-8207 J9 IEEE MICROW GUIDED W JI IEEE Microw. Guided Wave Lett. PD NOV PY 2000 VL 10 IS 11 BP 478 EP 480 DI 10.1109/75.888838 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA 381HJ UT WOS:000165756200012 ER PT J AU Oberg, J AF Oberg, J TI NASA's big push for the space station SO IEEE SPECTRUM LA English DT Article C1 NASA, Mission Control, Houston, TX 77058 USA. RP Oberg, J (reprint author), NASA, Mission Control, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9235 J9 IEEE SPECTRUM JI IEEE Spectr. PD NOV PY 2000 VL 37 IS 11 BP 49 EP 54 DI 10.1109/6.880954 PG 6 WC Engineering, Electrical & Electronic SC Engineering GA 373GL UT WOS:000165280500015 ER PT J AU Kumar, R Heymann, M AF Kumar, R Heymann, M TI Masked prioritized synchronization for interaction and control of discrete event systems SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Article DE controllability; discrete event system; masked prioritized synchronization; normality; supervisory control ID SUPERVISORY CONTROL; NONDETERMINISTIC SYSTEMS AB This paper extends the formalism of prioritized synchronous composition (PSC), proposed by Heymann for modeling interaction (and control) of discrete event systems, to permit system interaction with their environment via interface masks. This leads to the notion of masked prioritized synchronous composition (MPSC), which we formally define. MPSC can be used to model interaction of systems at single as well as multiple interfaces. We show that MPSC can alternatively be computed by "unmasking" the PSC of "masked" systems, thereby establishing a link between MPSC and PSC, We next prove that MPSC is associative and thus suitable for modeling and analysis of supervisory control of discrete event systems. Finally, we use MPSC of a discrete event plant and a supervisor for controlling the plant behavior and show (constructively) that under the absence of "driven" events, controllability together with normality of the given specification serve as conditions for the existence of a supervisor. This extends the results on supervisory control, which permits control and observation masks to be associated with the plant only. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Technion Israel Inst Technol, Dept Comp Sci, IL-32000 Haifa, Israel. RP Kumar, R (reprint author), Univ Kentucky, Dept Elect Engn, Lexington, KY 40506 USA. RI Kumar, Ratnesh/H-5309-2012 NR 19 TC 12 Z9 12 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD NOV PY 2000 VL 45 IS 11 BP 1970 EP 1982 PG 13 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA 378HQ UT WOS:000165579300002 ER PT J AU Bayard, DS AF Bayard, DS TI A general theory of linear time-invariant adaptive feedforward systems with harmonic regressors SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Article DE adaptive signal processing; asymptotic stability; feedforard systems; persistent excitation; robustness ID SINUSOIDAL REGRESSORS; LMS ALGORITHM; CANCELLATION; STABILITY; FILTER AB This paper establishes necessary and sufficient conditions for an adaptive system with a harmonic regressor (i.e., a regressor comprised exclusively of sinusoidal signals) to admit an exact linear time-invariant (LTI) representation. These conditions are important because a large number of adaptive systems used in practice have sinusoidal regressors, and the stability and performance of such systems having LTI representations can be completely analyzed by well-known methods. The theory is extended to applications where the LTI conditions do not hold, in which case the harmonic adaptive system can be written as the parallel connection of a purely LTI subsystem and a linear time-varying (LTV) subsystem. An explicit upper bound is established on the induced two-norm of the LTV block, which allows systematic treatment using emerging robust control methods applicable to LTI systems with norm-bounded LTV perturbations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bayard, DS (reprint author), CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NR 33 TC 19 Z9 19 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD NOV PY 2000 VL 45 IS 11 BP 1983 EP 1996 DI 10.1109/9.887622 PG 14 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA 378HQ UT WOS:000165579300003 ER PT J AU Ko, YC Alouini, MS Simon, MK AF Ko, YC Alouini, MS Simon, MK TI Outage probability of diversity systems over generalized fading channels SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Article; Proceedings Paper CT IEEE International Symposium on Information Theory (ISIT 2000) CY JUN, 2000 CL SORRENTO, ITALY SP IEEE DE correlated fading; diversity technique; equal-gain combining; maximal-ratio combining; Nakagami fading; outage probability ID PERFORMANCE AB Outage probability is an important performance measure of communication systems operating over fading channels. Relying on a simple and accurate algorithm for the numerical inversion of the Laplace transforms of cumulative distribution functions, we develop a moment generating function-based numerical technique for the outage probability evaluation of maximal-ratio combining (MRC) and postdetection equal-gain combining (EGC) in generalized fading channels for which the fading in each diversity path need not be independent, identically distributed, nor even distributed according to the same family of distributions. The method is then extended to coherent EGG but only for the case of Nakagami-m fading channels, The mathematical formalism is illustrated by applying the method to some selected numerical examples of interest showing the impact of the power delay profile and the fading correlation on the outage probability of MRC and EGC systems. C1 Univ Minnesota, Dept Elect & Comp Engn, Minneapolis, MN 55455 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Univ Minnesota, Dept Elect & Comp Engn, Minneapolis, MN 55455 USA. EM ycko@ece.umn.edu; alouini@ece.umne.du; marvin.k.simon@jpl.nasa.gov NR 8 TC 109 Z9 111 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0090-6778 EI 1558-0857 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD NOV PY 2000 VL 48 IS 11 BP 1783 EP 1787 PG 5 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 376LQ UT WOS:000165459400004 ER PT J AU Frederick, DK Garg, S Adibhatla, S AF Frederick, DK Garg, S Adibhatla, S TI Turbofan engine control design using robust multivariable control technologies SO IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY LA English DT Article DE aircraft engine control; gain scheduling; H-infinity; integral windup protection (IWP); integrator windup; limit protection; multivariable control; order reduction ID INFINITY AB A unified robust multivariable approach to propulsion control design has recently been developed at National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC). The critical elements of this unified approach are 1) a robust H-infinity control synthesis formulation; 2) a simplified controller scheduling scheme; and 3) a new approach to the synthesis of integrator windup protection gains for multivariable controllers, This paper presents results from an application of these technologies to control design for linear models of an advanced turbofan engine. The objectives of the study were to transfer technology to industry and to identify areas of further development for the technology to be applied by industry to the design of practical controllers for high-performance turbofan engines, The technology elements and industrial development of tools to implement the steps are described with respect to their application to a GE variable-cycle turbofan engine. A set of three-input/three-output three-state linear engine models was used over a range of power levels covering engine operation from idle to maximum unaugmented power. Results from simulation evaluation of H-infinity controller design, controller order reduction, controller scheduling, and integrator windup protection design are discussed and insight is provided into how the design parameter choices affect the results. C1 Unified Technol Inc, Troy, NY 12180 USA. NASA, Glen Res Ctr, Controls & Dynam Technol Branch, Cleveland, OH 44135 USA. GE Aircraft Engines, Six Sigma Grp, Cincinnati, OH 45215 USA. RP Frederick, DK (reprint author), Unified Technol Inc, Troy, NY 12180 USA. NR 16 TC 20 Z9 21 U1 0 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1063-6536 J9 IEEE T CONTR SYST T JI IEEE Trans. Control Syst. Technol. PD NOV PY 2000 VL 8 IS 6 BP 961 EP 970 DI 10.1109/87.880600 PG 10 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA 370EB UT WOS:000165109400009 ER PT J AU Imhoff, ML Tucker, CJ Lawrence, WT Stutzer, DC AF Imhoff, ML Tucker, CJ Lawrence, WT Stutzer, DC TI The use of multisource satellite and geospatial data to study the effect of urbanization on primary productivity in the United States SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE AVHRR; climate change; DMSP; NDVI; photosynthesis; primary productivity; urban heat island; urban sprawl ID LEAF-AREA INDEX; CITY LIGHTS; SPECTRAL REFLECTANCE; CANOPY REFLECTANCE; RADIATION; POPULATION; PHOTOSYNTHESIS; WHEAT AB Data from two different satellites, a digital land cover map, and digital census data were analyzed and combined in a geographic information system to study the effect of urbanization on photosynthetic productivity in the United States. Results show that urbanization can have a measurable but variable impact on the primary productivity of the land surface, Annual productivity can be reduced by as much as 20 days in some areas, but in resource limited regions, photosynthetic production can be enhanced by human activity, Overall, urban development reduces the productivity of the land surface, and those areas with the highest productivity are directly in the path of urban sprawl. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Imhoff, ML (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 38 TC 63 Z9 79 U1 3 U2 28 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 2000 VL 38 IS 6 BP 2549 EP 2556 PG 8 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 377AQ UT WOS:000165490100010 ER PT J AU Gu, DG Gillespie, AR Kahle, AB Palluconi, FD AF Gu, DG Gillespie, AR Kahle, AB Palluconi, FD TI Autonomous atmospheric compensation (AAC) of high resolution hyperspectral thermal infrared remote-sensing imagery SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE atmospheric compensation; emissivity; land surface temperature; precipitable water; remote sensing; thermal infrared ID LAND SURFACE-TEMPERATURE; WATER-VAPOR; MULTISPECTRAL SCANNER; EMISSIVITY; WINDOW; INFORMATION; RADIOMETER; ALGORITHM; EOS/MODIS; AIRBORNE AB Atmospheric emission and absorption significantly modify the thermal infrared (TIR) radiation spectra from Earth's land surface. A new algorithm, autonomous atmospheric compensation (AAC), was developed to estimate and compensate for the atmospheric effects, The algorithm estimates from hyperspectral TIR measurements two atmospheric index parameters, the transmittance ratio, and the path radiance difference between strong and weak absorption channels near the 11.73 mum water band. These two parameters depend on the atmospheric water and temperature distribution profiles, and thus, from them, the complete atmospheric transmittance and path radiance spectra can be predicted. The AAC algorithm is self-contained and needs no supplementary data. Its accuracy depends largely on instrument characteristics, particularly spectral and spatial resolution. Atmospheric conditions, especially humidity and temperature, and other meteorological parameters, also have some secondary impacts. The AAC algorithm was successfully applied to a hyperspectral TIR data set, and the results suggest its accuracy is comparable to that based on the in situ radiosonde measurements. C1 Remote Sensing Syst, Santa Rosa, CA 95403 USA. Univ Washington, Dept Geol Sci, Seattle, WA 98195 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Gu, DG (reprint author), Remote Sensing Syst, Santa Rosa, CA 95403 USA. NR 26 TC 48 Z9 50 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 2000 VL 38 IS 6 BP 2557 EP 2570 PG 14 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 377AQ UT WOS:000165490100011 ER PT J AU Kaufmann, RK Zhou, LM Knyazikhin, Y Shabanov, NV Myneni, RB Tucker, CJ AF Kaufmann, RK Zhou, LM Knyazikhin, Y Shabanov, NV Myneni, RB Tucker, CJ TI Effect of orbital drift and sensor changes on the time series of AVHRR vegetation index data SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE AVHRR; interannual variability; NDVI; pathfinder data; satellite drift ID PHOTOSYNTHETICALLY ACTIVE RADIATION; LEAF-AREA INDEX; SMALL-SCALE; UNIT-ROOT; REFLECTANCE; RESOLUTION; CANOPIES; COINTEGRATION; INTEGRATION; TEMPERATURE AB This paper assesses the effect of changes in solar zenith angle (SZA) and sensor changes on reflectances in channel 1, channel 2, and normalized difference vegetation index (NDVI) from the advanced very high resolution radiometer (AVHRR) Pathfinder land data set for the period July 1981 through September 1994, First, the effect of changes in SZA on channel reflectances and NDVI is derived from equations of radiative transfer in vegetation media. Starting from first principles, it is rigorously shown that the NDVI of a vegetated surface is a function of the maximum positive eigenvalue of the radiative transfer equation within the framework of the theory used and its assumptions. A sensitivity analysis of this relation indicates that NDVI is minimally sensitive to SZA changes, and this sensitivity decreases as leaf area increases, Second, statistical methods are used to analyze the relationship between SZA and channel reflectances or NDVI. It is shown that the use of ordinary least squares can generate spurious regressions because of the nonstationary property of time series. To avoid such a confusion, we use the notion of cointegration to analyze the relation between SZA and AVHRR data, Results are consistent with the conclusion of theoretical analysis from equations of radiative transfer, NDVI is not related to SZA in a statistically significant manner except for biomes with relatively low leaf area, From the theoretical and empirical analysis, we conclude that the NDVI data generated from the AVHRR Pathfinder land data set are not contaminated by trends introduced from changes in solar zenith angle due to orbital decay and changes in satellites (NOAA-7, 9, 11), As such, the NDVI data can be used to analyze interannual variability of global vegetation activity. C1 Boston Univ, Dept Geog, Boston, MA 02215 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. RP Kaufmann, RK (reprint author), Boston Univ, Dept Geog, Boston, MA 02215 USA. RI Zhou, Liming/A-2688-2012; Myneni, Ranga/F-5129-2012 NR 47 TC 120 Z9 125 U1 1 U2 12 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 2000 VL 38 IS 6 BP 2584 EP 2597 PG 14 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 377AQ UT WOS:000165490100013 ER PT J AU Sun, GQ Ranson, KJ AF Sun, GQ Ranson, KJ TI Modeling lidar returns from forest canopies SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE Forest growth model; lidar waveform; three-dimensional (3-D) model ID BIDIRECTIONAL REFLECTANCE; VEGETATION CANOPIES; BOREAL FORESTS; AREA AB Remote sensing techniques that utilize light detection and ranging (lidar) provide unique data on canopy geometry and subcanopy topography, This type of information will lead to improved understanding of important structures and processes of Earth's vegetation cover. To understand the relation between canopy structure and the lidar return waveform, a three-dimensional (3-D) model was developed and implemented. Detailed field measurements and forest growth model simulations of forest stands were used to parameterize this vegetation lidar waveform model. In the model, the crown shape of trees determines the vertical distribution of plant material and the corresponding lidar waveforms, Preliminary comparisons of averaged waveforms from an airborne lidar and model simulations shows that the shape of the measured waveform was more similar to simulations using an ellipsoid or hemi-ellipsoid shape, The observed slower decay of the airborne lidar waveforms than the simulated waveforms may indicate the existence of the understories and may also suggest that higher order scattering from the upper canopy may contribute to the lidar signals. The lidar waveforms from stands simulated from a forest growth model show the dependence of the waveform on stand structure. C1 Univ Maryland, Dept Geog, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. RP Sun, GQ (reprint author), Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RI Ranson, Kenneth/G-2446-2012 OI Ranson, Kenneth/0000-0003-3806-7270 NR 25 TC 95 Z9 111 U1 3 U2 22 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 2000 VL 38 IS 6 BP 2617 EP 2626 PG 10 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 377AQ UT WOS:000165490100016 ER PT J AU Siqueira, P Hensley, S Shaffer, S Hess, L McGarragh, G Chapman, B Freeman, A AF Siqueira, P Hensley, S Shaffer, S Hess, L McGarragh, G Chapman, B Freeman, A TI A continental-scale mosaic of the Amazon Basin using JERS-1 SAR SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID IMAGERY AB In this paper, a methodology, example and accuracy assessment are given for a continental-scale mosaic of the Amazon River basin at 100 m resolution using the JERS-1 satellite, This unprecedented resource of L-band SAR data collected by JERS-1 during the low-flood season of the river amounts to a collection of 57 orbits of the satellite and a total of some 1500 1 k x 1 kB images, Interscene overlap both in the along-track and cross-track directions allows common reference points to be used to correct individual scene geolocation inaccuracies that have been derived from the satellite ephemeris, The set of common reference points is assembled into a matrix formulation that is used to solve for individual scene geometric offsets. By correcting for these offsets, each scene is placed within a global coordinate system, which can then be used as the basis for creating a final, visually seamless mosaic. The methodology employed in this approach allows for a mathematical foundation to be applied to the mosaicking process as well as providing a unique, traceable solution for correctly geolocating satellite imagery. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Santa Barbara, Inst Computat Earth Syst Sci, Santa Barbara, CA 93106 USA. RP Siqueira, P (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Siqueira, Paul/D-9760-2016 OI Siqueira, Paul/0000-0001-5781-8282 NR 10 TC 34 Z9 34 U1 1 U2 10 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 2000 VL 38 IS 6 BP 2638 EP 2644 PG 7 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 377AQ UT WOS:000165490100018 ER PT J AU Njoku, EG Wilson, WJ Yueh, SH Rahmat-Samii, Y AF Njoku, EG Wilson, WJ Yueh, SH Rahmat-Samii, Y TI A large-antenna microwave radiometer-scatterometer concept for ocean salinity and soil moisture sensing SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE mesh antenna; radiometer; salinity; scatterometer; soil moisture ID MESH SURFACES AB Microwave radiometry and scatterometry are established techniques for surface remote sensing applications. Some applications, such as measurement of sea surface salinity (SSS), sea surface temperature, (SST), and soil moisture, require low frequency observations (similar to6 GHZ and below) for good sensitivity, and sensors with large antennas to achieve adequate spatial resolution. Potentially, benefits can he obtained by observing simultaneously with passive and active channels, at similar frequencies, viewing angles, and spatial resolutions, making use of the complementary information contained in the emissivity and backscattering signatures of land and ocean targets. in this study, we investigate a concept for combined passive and arrive multichannel sensing with high spatial resolution, high measurement sensitivity, and wide swath for frequent global coverage. The system consists of a lightweight, rotating, deployable mesh antenna with offset feeds, The system specifications are designed primarily for the measurement of sea surface salinity, since this application drives the precision and calibration requirements and, like soil moisture, is a science measurement for which no spaceborne capability currently exists. Demonstration of a capability for sea surface salinity will enhance the potential of this large antenna concept for other applications such as soil moisture and, by including higher frequencies, high resolution measurements of ocean winds, precipitation, sea-surface temperature, and sea-ice. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Elect Engn, Los Angeles, CA 90024 USA. RP Njoku, EG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 23 TC 36 Z9 38 U1 1 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD NOV PY 2000 VL 38 IS 6 BP 2645 EP 2655 PG 11 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 377AQ UT WOS:000165490100019 ER PT J AU Coffey, JT Klimesh, M AF Coffey, JT Klimesh, M TI Fundamental limits for information retrieval SO IEEE TRANSACTIONS ON INFORMATION THEORY LA English DT Article DE caches; context-dependent retrieval; databases; dimensionality; mass storage systems; random walks; replication of data; storage; typical sequences ID HIGH-PERFORMANCE; STORAGE; ARRAYS AB The fundamental limits of performance for a general model of information retrieval from databases are studied. In the scenarios considered, a large quantity of information is to be stored on some physical storage device. Requests for information are modeled as a randomly generated sequence with a known distribution. The requests are assumed to be "context-dependent," i.e., to vary according to the sequence of previous requests. The state of the physical storage device is also assumed to depend on the history of previous requests. In general, the logical structure of the information to be stored does not match the physical structure of the storage device, and consequently there are nontrivial limits on the minimum achievable average access times, where the average is over the possible sequences of user requests. The Paper applies basic information-theoretic methods to establish these limits and demonstrates constructive procedures that approach them, for a wide class of systems. Allowing redundancy greatly lowers the achievable access times, even when the amount added is an arbitrarily small fraction of the total amount of information in the database. The achievable limits both with and without redundancy are computed; in the case where redundancy is allowed the limits essentially coincide with lower limits for more general storage systems. C1 Texas Instruments Inc, Santa Rosa, CA 94116 USA. CALTECH, Jet Prop Lab, Commun Syst & Res Sect, Pasadena, CA 91109 USA. RP Texas Instruments Inc, Santa Rosa, CA 94116 USA. EM coffey@ti.com; klimesh@shannon.jpl.nasa.gov NR 49 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9448 EI 1557-9654 J9 IEEE T INFORM THEORY JI IEEE Trans. Inf. Theory PD NOV PY 2000 VL 46 IS 7 BP 2281 EP 2298 PG 18 WC Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 378VY UT WOS:000165606900001 ER PT J AU Ying, J Kirubarajan, T Pattipati, KR Patterson-Hine, A AF Ying, J Kirubarajan, T Pattipati, KR Patterson-Hine, A TI A hidden Markov model-based algorithm for fault diagnosis with partial and imperfect tests SO IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS PART C-APPLICATIONS AND REVIEWS LA English DT Article DE Baum-Welch algorithm; fault diagnosis; Hamming distance; hidden Markov models; imperfect tests; Viterbi decoding ID SET-COVERING PROBLEMS; PROBABILISTIC FUNCTIONS; SPEECH RECOGNITION; DYNAMIC-SYSTEMS AB ln this paper, we present a hidden Markov model (HMM) based algorithm for fault diagnosis in systems with partial and imperfect tests. The HMM-based algorithm Ends the most likely state evolution, given a sequence of uncertain test outcomes over time. We also present a method to estimate online the HMM parameters, namely, the state transition probabilities, the instantaneous probabilities of test outcomes given the system state and the initial state distribution, that are fundamental to HMM-based adaptive fault diagnosis, The efficacy of parameter estimation method is demonstrated by comparing the diagnostic accuracies of an algorithm with complete knowledge of HMM parameters with those of an adaptive one. In addition, the advantages of using the HMM approach over a Hamming-distance based fault diagnosis technique are quantified. Tradeoffs in computational complexity versus performance of the diagnostic algorithm are also discussed. C1 Univ Connecticut, Dept Elect & Syst Engn, Storrs, CT 06269 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Univ Connecticut, Dept Elect & Syst Engn, Storrs, CT 06269 USA. EM krishna@sol.uconn.edu; ann_potterson-hine@styx.arc.nasa.gov RI Kirubarajan, Thia/A-9770-2009 NR 32 TC 45 Z9 53 U1 2 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 1094-6977 EI 1558-2442 J9 IEEE T SYST MAN CY C JI IEEE Trans. Syst. Man Cybern. Part C-Appl. Rev. PD NOV PY 2000 VL 30 IS 4 BP 463 EP 473 DI 10.1109/5326.897073 PG 11 WC Computer Science, Artificial Intelligence; Computer Science, Cybernetics; Computer Science, Interdisciplinary Applications SC Computer Science GA 397AE UT WOS:000166669900007 ER PT J AU Greenhall, CA Dick, GJ AF Greenhall, CA Dick, GJ TI Local oscillator limited frequency stability for passive atomic frequency standards using square wave frequency modulation SO IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL LA English DT Article ID DEGRADATION; RESONATOR AB Atomic frequency standards using square wave frequency modulation effectively interrogate the atomic line by switching back and forth between two frequencies with equal atomic absorption values. For a symmetric absorption line, the slope of the responses will also be equal. In the quasistatic limit, this would seem to be an ideal interrogation process: the sign reversal of frequency slope can be removed by detection electronics to give an essentially unvarying sensitivity to local oscillator frequency variations. Such an interrogation would seem to eliminate L.O. aliasing and relieve stringent requirements on L.O. phase noise. Nevertheless, sign changes in the interrogation and detection processes mean that the sensitivity is actually zero at some point in the cycle. We derive consequences of this fact by an analysis in terms of the sensitivity function g(t). For white phase noise, we derive an optimal form for g(t) and show that the aliased noise always diverges as g(t) approaches a constant. For flicker phase noise, we find a limiting form that could, in principle, eliminate the aliasing effect; in practice, however, the improvement is limited by a slow dependence on available bandwidth. Finally, we derive optimized forms for any phase noise spectrum. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Greenhall, CA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 4 Z9 4 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0885-3010 J9 IEEE T ULTRASON FERR JI IEEE Trans. Ultrason. Ferroelectr. Freq. Control PD NOV PY 2000 VL 47 IS 6 BP 1593 EP 1600 DI 10.1109/58.883548 PG 8 WC Acoustics; Engineering, Electrical & Electronic SC Acoustics; Engineering GA 371HE UT WOS:000165172200035 PM 18238705 ER PT J AU Zak, M AF Zak, M TI Physical model of immune inspired computing SO INFORMATION SCIENCES LA English DT Article AB Artificial immune system is a rapidly growing field of information processing and computing based upon immune inspired paradigms of nonlinear dynamics. This paper introduces stochastic models which mimic the phenomenology of basic functions of immune systems such as self-nonself discrimination, self-repair, predator-prey pursuit, and reproduction. These models represent a unified formalism for building an artificial immune system for effective information processing and computing. (C) 2000 Elsevier Science Inc. All rights reserved. C1 CALTECH, Jet Prop Lab, Ultracomp Grp, Pasadena, CA 91109 USA. RP Zak, M (reprint author), CALTECH, Jet Prop Lab, Ultracomp Grp, 4800 Oak Grove Dr,M-S 126-347, Pasadena, CA 91109 USA. NR 12 TC 8 Z9 12 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0020-0255 J9 INFORM SCIENCES JI Inf. Sci. PD NOV PY 2000 VL 129 IS 1-4 BP 61 EP 79 DI 10.1016/S0020-0255(00)00063-3 PG 19 WC Computer Science, Information Systems SC Computer Science GA 383UC UT WOS:000165900400005 ER PT J AU Chapman, DW Snyder, CW AF Chapman, DW Snyder, CW TI Can high stakes national testing improve instruction. reexamining conventional wisdom SO INTERNATIONAL JOURNAL OF EDUCATIONAL DEVELOPMENT LA English DT Article DE testing; assessment; educational policy; school improvement ID INTERNATIONAL ASSESSMENTS; ACHIEVEMENT; POLICY; WORLD AB In this paper, the authors draw on recent international experience to assess the success of five propositions for how high stakes national testing can improve classroom instruction and, ultimately, raise student achievement. Findings indicate that testing can be an effective mechanism for improving instructional practice, but its success is not ensured. It has failed as often as it has succeeded, usually because those implementing the strategy failed to understand the intermediate conditions that had to be met for changes in test content, format, or use to have the desired impact on teachers' classroom practice. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Minnesota, Coll Educ, Minneapolis, MN 55455 USA. Univ Montana, NASA, EOS Educ Project, Missoula, MT 59812 USA. RP Chapman, DW (reprint author), Univ Minnesota, Coll Educ, 330 Wulling Hall,86 Pleasant St SE, Minneapolis, MN 55455 USA. NR 38 TC 12 Z9 12 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0738-0593 J9 INT J EDUC DEV JI Int. J. Educ. Dev. PD NOV PY 2000 VL 20 IS 6 BP 457 EP 474 DI 10.1016/S0738-0593(00)00020-1 PG 18 WC Education & Educational Research SC Education & Educational Research GA 362VG UT WOS:000089798500003 ER PT J AU Cucinotta, FA Nikjoo, H O'Neill, P Goodhead, DT AF Cucinotta, FA Nikjoo, H O'Neill, P Goodhead, DT TI Kinetics of DSB rejoining and formation of simple chromosome exchange aberrations SO INTERNATIONAL JOURNAL OF RADIATION BIOLOGY LA English DT Article ID DOUBLE-STRAND BREAKS; ULTRASOFT X-RAYS; INDUCED CHROMATIN BREAKS; V79-4 MAMMALIAN-CELLS; IN-SITU HYBRIDIZATION; DNA-REPAIR KINETICS; HUMAN-LYMPHOCYTES; IONIZING-RADIATION; HUMAN FIBROBLASTS; ALPHA-PARTICLES AB Purpose : To investigate the role of kinetics in the processing of DNA double strand breaks (DSB), and the formation of simple chromosome exchange aberrations following X-ray exposures to mammalian cells based on an enzymatic approach. Methods: Using computer simulations based on a biochemical approach, rate-equations that describe the processing of DSB through the formation of a DNA-enzyme complex were formulated. A second model that allows for competition between two processing pathways was also formulated. The formation of simple exchange aberrations was modelled as misrepair during the recombination of single DSB with undamaged DNA. Non-linear coupled differential equations corresponding to biochemical pathways were solved numerically by fitting to experimental data. Results: When mediated by a DSB-repair enzyme complex, the processing of single DSB showed a complex behaviour that gives the appearance of fast and slow components of rejoining. This is due to the time-delay caused by the action time of enzymes in biomolecular reactions. It is shown that the kinetic- and dose-responses of simple chromosome exchange aberrations are well described by a recombination model of DSB interacting with undamaged DNA when aberration formation increases with linear dose-dependence. Competition between two or more recombination processes is shown to lead to the formation of simple exchange aberrations with a dose-dependence similar to that of a linear-quadratic model. Conclusions : Using a minimal number of assumptions, the kinetics and dose-response observed experimentally for DSB rejoining and the formation of simple chromosome exchange aberrations are shown to be consistent with kinetic models based on enzymatic reaction approaches. A non-linear dose-response for simple exchange aberrations is possible in a model of recombination of DNA containing a DSB with undamaged DNA when two or more pathways compete for DSB repair. C1 NASA, Space & Life Sci Directorate, Houston, TX 77058 USA. MRC, Radiat & Genome Stabil Unit, Didcot OX11 0RD, Oxon, England. RP Cucinotta, FA (reprint author), NASA, Space & Life Sci Directorate, Mail Code SN, Houston, TX 77058 USA. NR 57 TC 54 Z9 55 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0955-3002 J9 INT J RADIAT BIOL JI Int. J. Radiat. Biol. PD NOV PY 2000 VL 76 IS 11 BP 1463 EP 1474 PG 12 WC Biology; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging GA 371AG UT WOS:000165155000004 PM 11098849 ER PT J AU Justice, C Belward, A Morisette, J Lewis, P Privette, J Baret, F AF Justice, C Belward, A Morisette, J Lewis, P Privette, J Baret, F TI Developments in the 'validation' of satellite sensor products for the study of the land surface SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID MODIS; NETWORK AB Increased availability of global satellite sensor data is resulting in an increase in satellite sensor products for global change research and environmental monitoring. The ensuing research and policy directives that will utilize these satellite products puts a high priority on providing statements of their accuracy. The process of quantifying the accuracy of these geophysical products is herein termed 'validation'. This Letter provides examples of international land product 'validation' research and describes a new international forum for coordination within the Committee on Earth Observation Satellites (CEOS) Calibration and Validation Working Group (CVWG). C1 Univ Virginia, Dept Environm Sci, Charlottesville, VA 22903 USA. Commiss European Communities, Joint Res Ctr, I-21020 Ispra, Italy. Univ Maryland, NASA, GSFC, Dept Geog, Greenbelt, MD 20770 USA. Univ London, Dept Geog, London WC1H 0AP, England. INRA Bioclimatol, F-84914 Avignon, France. RP Justice, C (reprint author), Univ Virginia, Dept Environm Sci, Clark Hall, Charlottesville, VA 22903 USA. RI Lewis, Philip/C-1588-2008; Privette, Jeffrey/G-7807-2011; Baret, Fred/C-4135-2011 OI Lewis, Philip/0000-0002-8562-0633; Privette, Jeffrey/0000-0001-8267-9894; Baret, Fred/0000-0002-7655-8997 NR 25 TC 109 Z9 119 U1 4 U2 16 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD NOV PY 2000 VL 21 IS 17 BP 3383 EP 3390 DI 10.1080/014311600750020000 PG 8 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA 371TW UT WOS:000165195300020 ER PT J AU Chung, J Reehorst, A Choo, Y Potapczuk, M Slater, J AF Chung, J Reehorst, A Choo, Y Potapczuk, M Slater, J TI Navier-Stokes analysis of flowfield characteristics of an ice-contaminated aircraft wing SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 37th Aerospace Sciences Meeting and Exhibit CY JAN 11-14, 1999 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut AB An analytical study was performed as part of the NASA John H, Glenn Research Center support of a National Transportation Safety Board aircraft accident investigation. The study focused on the performance degradation associated with ice contamination on the wing of a commercial turboprop-powered aircraft. Based on the results of an earlier numerical study, a prominent ridged-ice formation on the subject aircraft wing was selected for detailed flow analysis using two-dimensional, as well as three-dimensional, Navier-Stokes computations. This configuration was selected because it caused the largest lift decrease and drag increase among all of the ice shapes investigated in the earlier study. A grid sensitivity test was performed to find out the influence of grid spacing on the lift, drag, and associated angle of attack for the maximum lift (alphaC(lmax). This study shelved that grid resolution is important and a sensitivity analysis is an essential element of the process to assure that the final solution is independent of the grid. The two-dimensional results suggested that a severe stability and control difficulty could have occurred at a slightly higher angle of attack (AOA) than the one recorded by the flight data recorder. A decreased differential lift on the wings with respect to the normal loading for the configuration was thought to have contributed to the control upset. The analysis also indicated that this stability and control problem could have occurred whether or not natural ice shedding took place. Numerical results using an assumed three-dimensional ice shape showed an increase of the angle at which this phenomena occurred of about 4 deg. As with the two-dimensional case, the trailing-edge separation was observed but started only when the AOA was very close to the angle at which the maximum lift occurred. C1 NASA, John H Glenn Res Ctr, Inst Computat Mech, Cleveland, OH 44135 USA. NASA, John H Glenn Res Ctr, Icing Branch, Cleveland, OH 44135 USA. NASA, John H Glenn Res Ctr, Inlet Branch, Cleveland, OH 44135 USA. RP Chung, J (reprint author), NASA, John H Glenn Res Ctr, Inst Computat Mech, Lewis Field, Cleveland, OH 44135 USA. NR 13 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 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2000 VL 37 IS 6 BP 947 EP 959 DI 10.2514/2.2716 PG 13 WC Engineering, Aerospace SC Engineering GA 381TA UT WOS:000165778500002 ER PT J AU Rossow, VJ James, KD AF Rossow, VJ James, KD TI Overview of wake-vortex hazards during cruise SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 17th Applied Aerodynamics Conference CY JUN 28-JUL 01, 1999 CL NORFOLK, VIRGINIA SP Amer Inst Aeronaut & Astronaut ID TRAILING VORTICES; STRATIFIED FLUID; GENERATED WAKES; WIND-TUNNEL; INSTABILITY; CIRRUS; LOADS AB A large amount of research effort has been devoted to the hazard posed by lift-generated vortex wakes of subsonic transport ail-craft during approach and departure at airports. In contrast, only a smell amount of effort has gone into the corresponding potential hazard at cruise attitudes. Because more frequent encounters with wakes may occur as the density of aircraft increases with time, improved knowledge is needed of the persistence and magnitude of the hazard posed by lift-generated wakes at cruise altitudes. The purpose here is to review and then to extend previous work to characterize properly the hazard posed by vortex makes at cruise altitudes. Photographs are presented of the various fluid dynamic stages that vortex wakes usually go through as they age. Estimates made of the potential hazard that each stage poses indicate that the rolling-moment hazard during an axial encounter of a vortex wake can be as severe at cruise as far approach at airports; however, as in the airport-approach case, the hazard only persists for several minutes (about 20 n mile) behind the generating aircraft. However, the hazard posed by the downwash in the wake persists for up to tens of minutes (about 200 n mite) behind the generating aircraft. The downwash hazard is realized as severe vertical loads. ii technique for avoiding vortex wakes at cruise altitude is described. C1 NASA, Ames Res Ctr, Aerosp Operat Modeling Off, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Expt Phys Branch, Moffett Field, CA 94035 USA. RP Rossow, VJ (reprint author), NASA, Ames Res Ctr, Aerosp Operat Modeling Off, Mail Stop 210-10, Moffett Field, CA 94035 USA. NR 60 TC 12 Z9 14 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2000 VL 37 IS 6 BP 960 EP 975 DI 10.2514/2.2723 PG 16 WC Engineering, Aerospace SC Engineering GA 381TA UT WOS:000165778500003 ER PT J AU Czerwiec, R Edwards, JR Rumsey, CL Bertelrud, A Hassan, HA AF Czerwiec, R Edwards, JR Rumsey, CL Bertelrud, A Hassan, HA TI Study of high-lift configurations using k-zeta transition/turbulence model SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 17th Applied Aerodynamics Conference CY JUN 28-JUL 01, 1999 CL NORFOLK, VIRGINIA SP Amer Inst Aeronaut & Astronaut ID CLOSURE-MODEL; FLOWS AB The how over the multi-element McDonnell Douglas configuration is computed using the k-zeta transition/turbulence model. The model is capable of calculating transition onset as part of the solution at a cost comparable to Navier-Stokes solvers that employ two-equation models. The model is first incorporated into CFL3D and then used to calculate hows for two angles of attack, 8 and 19 deg, at a freestream Mach number of 0.2 and a Reynolds number of 9 x 10(6), In general, good agreement is indicated for predicting transition onset and velocity profiles over sections of the main airfoil and Rap. Most of the differences between computation and experiment are in the prediction of the extent and penetration of the slat wake at the 19-deg angle-of-attack case. Even far this case relative differences were less than 5%. C1 N Carolina State Univ, Fluid Mech & Acoust Div, Raleigh, NC 27695 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Analyt Serv & Mat Inc, Hampton, VA 23666 USA. RP Czerwiec, R (reprint author), N Carolina State Univ, Fluid Mech & Acoust Div, Box 7910, Raleigh, NC 27695 USA. NR 27 TC 10 Z9 10 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2000 VL 37 IS 6 BP 1008 EP 1016 DI 10.2514/2.2728 PG 9 WC Engineering, Aerospace SC Engineering GA 381TA UT WOS:000165778500008 ER PT J AU Lind, R Brenner, M AF Lind, R Brenner, M TI Flutterometer: An on-line tool to predict robust flutter margins SO JOURNAL OF AIRCRAFT LA English DT Article ID FLIGHT DATA AB Robust flutter margins can be computed for an aeroelastic model with respect to an associated uncertainty description that describes modeling errors. An on-line implementation to compute these robust margins is considered. The on-line approach generates uncertainty descriptions at test points and can account for time-varying errors in the model. A flutterometer is introduced as an on-line tool to indicate a measure of distance to flutter during a flight flutter test. Such a tool is formulated based on robust flutter margin analysis. A flight test of an F/A-18 is simulated to demonstrate the performance of the flutterometer. This tool is clearly more informative than traditional tracking of damping trends and provides accurate information about the true flutter margin throughout the flight test. The simulation demonstrates characteristics of the flutterometer that Could improve flight test efficiency by increasing safety and reducing flight time for envelope expansion. C1 NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. RP Lind, R (reprint author), NASA, Dryden Flight Res Ctr, MS 4840D-RS, Edwards, CA 93523 USA. NR 30 TC 35 Z9 38 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2000 VL 37 IS 6 BP 1105 EP 1112 DI 10.2514/2.2719 PG 8 WC Engineering, Aerospace SC Engineering GA 381TA UT WOS:000165778500022 ER PT J AU Zhou, Y Hayder, ME Rubinstein, R AF Zhou, Y Hayder, ME Rubinstein, R TI Model for radiated sound from high-Reynolds-number turbulence source SO JOURNAL OF AIRCRAFT LA English DT Article ID ISOTROPIC TURBULENCE; TIME CORRELATIONS; GENERATION C1 NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. Rice Univ, Ctr Res High Performance Software, Houston, TX 77005 USA. RP Zhou, Y (reprint author), NASA, Langley Res Ctr, Inst Comp Applicat Sci & Engn, Hampton, VA 23681 USA. NR 18 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD NOV-DEC PY 2000 VL 37 IS 6 BP 1113 EP 1115 DI 10.2514/2.2720 PG 3 WC Engineering, Aerospace SC Engineering GA 381TA UT WOS:000165778500023 ER PT J AU Romanov, P Gutman, G Csiszar, I AF Romanov, P Gutman, G Csiszar, I TI Automated monitoring of snow cover over North America with multispectral satellite data SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID REFLECTANCE MODEL; IMAGERY; IDENTIFICATION; RESOLUTION; PRODUCTS; SURFACE; CLOUDS AB Current National Oceanic and Atmospheric Administration (NOAA) operational global- and continental-scale snow cover maps are produced interactively by visual analysis of satellite imagery. This snow product is subjective, and its preparation requires a substantial daily human effort. The primary objective of the current study was to develop an automated system that could provide NOAA analysts with a first-guess snow cover map and thus to reduce the human labor in the daily snow cover analysis. The proposed system uses a combination of observations in the visible, midinfrared, and infrared made by the Imager instrument aboard Geostationary Operational Environmental Satellites (GOES) and microwave observations of the Special Sensor Microwave Imager (SSM/I) aboard the polar-orbiting Defense Meteorological Satellite Program platform. The devised technique was applied to satellite data for mapping snow cover for the North American continent during the winter season of 1998/99. To assess the system performance, the automatically produced snow maps were compared with the NOAA interactive operational product and were validated against in situ land surface observations. Validation tests revealed that in 85% of cases the automated snow maps fit exactly the ground snow cover reports. Snow identification with the combination of GOES and SSM/I observations was found to be more efficient than the one based solely on satellite microwave data. Comparisons between the automated maps and the NOAA operational product have shown their good agreement in the distribution of snow covet and its area coverage. The accuracy of the automated product was found to be similar to and sometimes higher than the accuracy of the operational snow cover maps manually produced at NOAA. C1 NOAA, NESDIS, ORA, Camp Springs, MD 20746 USA. NASA Headquarters, Washington, DC USA. RP Romanov, P (reprint author), NOAA, NESDIS, ORA, WWB 712,5200 Auth Rd, Camp Springs, MD 20746 USA. RI Romanov, Peter/F-5622-2010; Csiszar, Ivan/D-2396-2010 OI Romanov, Peter/0000-0002-2153-8307; NR 23 TC 76 Z9 82 U1 0 U2 8 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD NOV PY 2000 VL 39 IS 11 BP 1866 EP 1880 DI 10.1175/1520-0450(2000)039<1866:AMOSCO>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 378QF UT WOS:000165594500007 ER PT J AU Li, JZ Ning, CZ AF Li, JZ Ning, CZ TI Plasma heating and ultrafast semiconductor laser modulation through a terahertz heating field SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID EFFECTIVE BLOCH EQUATIONS; SURFACE-EMITTING LASERS; SATURATION; AMPLIFIERS; DYNAMICS AB Electron-hole plasma heating and ultrafast modulation in a semiconductor laser under a terahertz electrical field are investigated using a set of hydrodynamic equations derived from the semiconductor Bloch equations. The self-consistent treatment of lasing and heating processes leads to the prediction of a strong saturation and degradation of modulation depth even at moderate terahertz field intensity. This saturation places a severe limit to bandwidth achievable with such scheme in ultrafast modulation. Strategies for increasing modulation depth are discussed. (C) 2000 American Institute of Physics. [S0021-8979(00)03622-7]. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Li, JZ (reprint author), NASA, Ames Res Ctr, M-S N229-1, Moffett Field, CA 94035 USA. EM jianzhng@nas.nasa.gov; cning@nas.nasa.gov RI Ning, C. Z./D-4699-2009 OI Ning, C. Z./0000-0003-4583-8889 NR 27 TC 2 Z9 2 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD NOV 1 PY 2000 VL 88 IS 9 BP 4933 EP 4940 AR PII [S0021-8979(00)03622-7] DI 10.1063/1.1315613 PG 8 WC Physics, Applied SC Physics GA 363BL UT WOS:000089813800001 ER PT J AU Su, CH Feth, S Zhu, S Lehoczky, SL Wang, LJ AF Su, CH Feth, S Zhu, S Lehoczky, SL Wang, LJ TI Optical characterization of bulk ZnSeTe solid solutions SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID MOLECULAR-BEAM EPITAXY; SELENIDE SINGLE-CRYSTALS; HIGH-PURITY; ZINC SELENIDE; PHOTOLUMINESCENCE SPECTRA; BAND-GAP; EXCITON; ZNSEXTE1-X; ALLOYS; DONOR AB Optical characterization was performed on wafers sliced from crystals of ZnSe, ZnTe, and ZnSe1-xTex(0 < x < 0.4) grown by physical vapor transport. Energy band gaps at room temperature were determined from optical transmission measurements on 11 wafers. A best fit curve to the band gap versus composition x data gives a bowing parameter of 1.45. This number lies between the value of 1.23 determined previously on ZnSeTe bulk crystals and the value of 1.621 reported on ZnSeTe epilayers. Low-temperature photoluminescence (PL) spectra were measured on six samples. The spectra of ZnSe and ZnTe were dominated by near band edge emissions and no deep donor-acceptor pairs were observed. The PL spectrum exhibited a broad emission for each of the ZnSe1-xTex samples, 0.09 < x < 0.39. For x=0.09, this emission energy is about 0.2 eV lower than the band gap energy measured at low temperature. As x increases the energy discrepancy gradually decreases and reduces to almost zero at x=0.4. The single broad PL emission spectra and the spectra measured as a function of temperature were interpreted as being associated with the exciton bound to Te clusters because of the high Te content in these samples. (C) 2000 American Institute of Physics. [S0021-8979(00)03222-9]. C1 NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Sci Directorate SD47, Huntsville, AL 35812 USA. Univ Tennessee, Dept Phys Geol & Astron, Chattanooga, TN 37403 USA. Univ Alabama, Huntsville, AL 35899 USA. Univ Space Res Assoc, Washington, DC USA. RP Su, CH (reprint author), NASA, George C Marshall Space Flight Ctr, Micrograv Sci & Applicat Dept, Sci Directorate SD47, Huntsville, AL 35812 USA. RI Feth, Shari/F-6302-2013 OI Feth, Shari/0000-0003-3545-5649 NR 32 TC 15 Z9 15 U1 0 U2 6 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD NOV 1 PY 2000 VL 88 IS 9 BP 5148 EP 5152 DI 10.1063/1.1315330 PG 5 WC Physics, Applied SC Physics GA 363BL UT WOS:000089813800033 ER PT J AU Convertino, VA Luetkemeier, MJ Elliott, JJ Ludwig, DA Wade, CE AF Convertino, VA Luetkemeier, MJ Elliott, JJ Ludwig, DA Wade, CE TI Renal responsiveness to aldosterone during exposure to simulated microgravity SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE bed rest; natriuresis; renal function; plasma renin activity; antidiuretic hormone; atrial natriuretic peptide ID SPACE-FLIGHT; ENDOCRINE; RESPONSES; VOLUME; HUMANS AB We measured renal functions and hormones associated with fluid regulation after a bolus injection of aldosterone (Ald) during head-down tilt (HDT) bed rest to test the hypothesis that exposure to simulated microgravity altered renal responsiveness to Aid. Six male rhesus monkeys underwent two experimental conditions (HDT and control, 72 h each) with each condition separated by 9 days of ambulatory activities to produce a crossover counterbalance design. One test condition was continuous exposure to 10 degrees HDT; the second was a control, defined as 16 h per day of 80 degrees head-up tilt and 8 h prone. After 72 h of exposure to either test condition, monkeys were moved to the prone position, and we measured the following parameters for 4 h after injection of l-mg dose of Ald: urine volume rate (UVR); renal Na+/K+ excretion ratio; renal clearances of creatinine, Na+, osmolality, and free water; and circulating hormones [Ald, renin activity (PRA), vasopressin (AVP), and atrial natriuretic peptide (ANP)I. HDT increased Na+ clearance, total renal Na+ excretion, urine Na+ concentration, and fractional Na+ excretion, compared with the control condition, but did not alter plasma concentrations of Aid, PRA, and AVP. Administration of Ald did not alter UVR, creatinine clearance, Aid, PRA, AVP, or ANP but reduced Na+ clearance, total renal Na+ excretion, urinary Na+/K+ ratio, and osmotic clearance. Although reductions in Na+ clearance and excretion due to Aid were greater during HDT than during control, the differential (i.e., interaction) effect was minimal between experimental conditions. Our data suggest that exposure to microgravity increases renal excretion of Na+ by a natriuretic mechanism other than a change in renal responsiveness to Aid. C1 USA, Inst Surg Res, Ft Sam Houston, TX 78234 USA. Univ Utah, Dept Exercise Sci, Salt Lake City, UT 84103 USA. USA, Med Dept & Sch, Dept Vet Med, Ft Sam Houston, TX 78234 USA. Univ N Carolina, Dept Math Sci, Greensboro, NC 27412 USA. NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 95070 USA. RP Convertino, VA (reprint author), USA, Inst Surg Res, 3400 Rawley E Chambers Ave,Bldg 3611, Ft Sam Houston, TX 78234 USA. NR 22 TC 6 Z9 7 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD NOV PY 2000 VL 89 IS 5 BP 1737 EP 1743 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 369FH UT WOS:000165054900008 PM 11053320 ER PT J AU Darquenne, C Paiva, M Prisk, GK AF Darquenne, C Paiva, M Prisk, GK TI Effect of gravity on aerosol dispersion and deposition in the human lung after periods of breath holding SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE aerosol bolus; cardiogenic mixing ID RESPIRATORY-TRACT; BOLUS DISPERSION; HEART-RATE; MICROGRAVITY; HYPERGRAVITY; VOLUMES AB To determine the extent of the role that gravity plays in dispersion and deposition during breath holds, we performed aerosol bolus inhalations of 1-mum-diameter particles followed by breath holds of various lengths on four subjects on the ground (1G) and during short periods of microgravity (muG). Boluses of similar to 70 mi were inhaled to penetration volumes (V-p) of 150 and 500 mi, at a constant flow rate of similar to0.45 l/s. Aerosol concentration and flow rate were continuously measured at the mouth. Aerosol deposition and dispersion were calculated from these data. Deposition was independent of breath-hold time at both V-p in muG, whereas, in 1G, deposition increased with increasing breath hold time. At V-p = 150 mi, dispersion was similar at both gravity levels and increased with breath hold time. At V-p = 500 mi, dispersion in 1G was always significantly higher than in muG. The data provide direct evidence that gravitational sedimentation is the main mechanism of deposition and dispersion during breath holds. The data also suggest that cardiogenic mixing and turbulent mixing contribute to deposition and dispersion at shallow V-p. C1 Univ Calif San Diego, Dept Med, La Jolla, CA 92093 USA. Free Univ Brussels, Biomed Phys Lab, B-1070 Brussels, Belgium. RP Darquenne, C (reprint author), NASA, Physiol Lab 0931, 9500 Gilman Dr, La Jolla, CA 92093 USA. NR 25 TC 20 Z9 20 U1 0 U2 2 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD NOV PY 2000 VL 89 IS 5 BP 1787 EP 1792 PG 6 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 369FH UT WOS:000165054900015 PM 11053327 ER PT J AU Sterling, AC AF Sterling, AC TI Sigmoid CME source regions at the Sun: some recent results SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT IUGG/IAGA General Assembly CY JUL, 1999 CL UNIV BIRMINGHAM, BIRMINGHAM, ENGLAND SP IUGG, IAGA, Sci Comm Solar Terrestrial Phys HO UNIV BIRMINGHAM DE solar flares; coronal mass ejections (CMEs); solar EUV/X-rays; space weather ID CORONAL MASS EJECTIONS; EARTH CONNECTION EVENT; SOLAR-A MISSION; X-RAY EVENTS; MAGNETIC CLOUD; DISAPPEARING-FILAMENT; GEOMAGNETIC STORM; RADIO EMISSIONS; JANUARY 1997; FLARE AB Identifying coronal mass ejection (CME) precursors in the solar corona would be an important step in space weather forecasting, as well as a vital key to understanding the physics of CMEs. Twisted magnetic field structures are suspected of being the source of at least some CMEs. These features can appear sigmoid (S or inverse-S) shaped in soft X-ray (SXR) images. We review recent observations of these structures and their relation to CMEs, using S,YR data from the Soft X-ray Telescope (SXT) on the Yohkoh satellite, and EUV data from the EUV Imaging Telescope (EIT) on the SOHO satellite. These observations indicate that the pre-eruption sigmoid patterns are more prominent in SXRs than in EW, and that sigmoid precursors are present in over 50% of CMEs. These findings are important for CME research, and may potentially be a major component to space weather forecasting. So far, however, the studies have been subject to restrictions that will have to be relaxed before sigmoid morphology can be used as a reliable predictive tool. Moreover, some CMEs do not display a SXR sigmoid structure prior to eruption, and some others show no prominent SXR signature of any kind before or during eruption. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, George C Marshall Space Flight Ctr, Space Sci Dept SD50, Huntsville, AL 35812 USA. RP Sterling, AC (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Dept SD50, Huntsville, AL 35812 USA. NR 78 TC 28 Z9 32 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD NOV PY 2000 VL 62 IS 16 BP 1427 EP 1435 DI 10.1016/S1364-6826(00)00089-4 PG 9 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 377PK UT WOS:000165521900003 ER PT J AU van Driel-Gesztelyi, L Manoharan, PK Demoulin, P Aulanier, G Mandrini, CH Lopez-Fuentes, M Schmieder, B Orlando, S Thompson, B Plunkett, S AF van Driel-Gesztelyi, L Manoharan, PK Demoulin, P Aulanier, G Mandrini, CH Lopez-Fuentes, M Schmieder, B Orlando, S Thompson, B Plunkett, S TI Initiation of CMEs: the role of magnetic twist SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT IUGG/IAGA General Assembly CY JUL, 1999 CL UNIV BIRMINGHAM, BIRMINGHAM, ENGLAND SP IUGG, IAGA, Sci Comm Solar Terrestrial Phys HO UNIV BIRMINGHAM DE coronal mass ejections; magnetic twist ID CONFIGURATIONS SUPPORTING PROMINENCES; CORONAL MASS EJECTIONS; FLUX-ROPE MODELS; SOLAR-A MISSION; ERUPTIVE FLARES; MAXIMUM ENERGY; LATERAL FEET; FIELD; RECONNECTION; RADIO AB Recent multiwavelength observations, modelling results and theoretical developments indicate the importance of twisted magnetic configurations in solar active regions (ARs) in the initiation of coronal mass ejections (CMEs). Through multiwavelength analysis of a few representative events we make an attempt to provide constraints for CME models. The two events presented here in detail start with the expansion of sigmoids (S- or inverse S-shaped loops) observed in soft X-rays. Both events (on 25 October 1994 and 14 October 1995) occurred before the launch of the SOHO spacecraft, but indirect evidences (i.,e. signatures of an outward propagation traced up to approximate to 20 solar radii and an associated magnetic cloud) suggest that both of them were related to CMEs. We show evidence that sigmoids are the coronal manifestations of twisted magnetic flux tubes, which start expanding presumably due to a loss of equilibrium, It is noteworthy that the analysed CMEs occurred in a complex (not simply bipolar) magnetic environment and in all cases we found evidences of the interaction (magnetic reconnection) with the surrounding fields. We propose a scenario for sigmoid expansion related CME events and suggest that twisted magnetic configurations are good candidates for being source regions of CMEs. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Observ Paris, DASOP, F-92195 Meudon, France. Konkoly Observ Budapest, H-1525 Budapest, Hungary. Tata Inst Fundamental Res, Radio Astron Ctr, NCRA, Udhagamandalam, Ooty, India. USN, Res Lab, Washington, DC 20375 USA. George Mason Univ, CSI, Fairfax, VA 22030 USA. CONICET, IAFE, RA-1428 Buenos Aires, DF, Argentina. Univ Oslo, N-0315 Oslo, Norway. Osservatorio Astron Palermo GS Vaiana, I-90134 Palermo, Italy. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, Res Lab, USRA, Washington, DC 20375 USA. RP van Driel-Gesztelyi, L (reprint author), Observ Paris, DASOP, F-92195 Meudon, France. RI Thompson, Barbara/C-9429-2012; OI Demoulin, Pascal/0000-0001-8215-6532; Lopez Fuentes, Marcelo/0000-0001-8830-4022; Orlando, Salvatore/0000-0003-2836-540X NR 62 TC 20 Z9 20 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD NOV PY 2000 VL 62 IS 16 BP 1437 EP 1448 DI 10.1016/S1364-6826(00)00087-0 PG 12 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 377PK UT WOS:000165521900004 ER PT J AU Biesecker, DA Thompson, BJ AF Biesecker, DA Thompson, BJ TI Sympathetic flaring with BATSE, GOES, and EIT data SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT IUGG/IAGA General Assembly CY JUL, 1999 CL UNIV BIRMINGHAM, BIRMINGHAM, ENGLAND SP IUGG, IAGA, Sci Comm Solar Terrestrial Phys HO UNIV BIRMINGHAM DE sympathetic flaring; solar flare; flare initiation ID X-RAY-BURSTS; SOLAR-FLARES; MODELS AB Sympathetic flaring is defined as the initiation of a solar flare as a result of a transient phenomenon occurring elsewhere on the Sun. Discovery of sympathetic flaring or lack thereof, may lead to a greater understanding of the physics of flare initiation. Knowledge of a mechanism for initiating solar flares would also aid in predicting at least some solar flares. Two studies of sympathetic flaring are presented in this paper. The first part of the paper presents a test for sympathetic flaring in flares observed with the Burst and Transient Source Experiment. A Monte Carlo simulation is used to compare the distribution of solar X-ray flares in time to that expected from a time-varying, Poisson distribution. No evidence for sympathetic flaring is found, though it cannot be ruled out. The X-ray flare data also do not allow discovery of sympathetic flares occurring within 2 min of the initial flare. Because the observations do allow for at least some flares to occur sympathetically, the second part of the paper examines one possible mechanism for initiating flares. The mechanism examined is large-scale coronal transients observed by the SOHO/Extreme Ultraviolet Imaging Telescope: EIT waves. A comparison of the rate of flaring in the interval prior to an EIT wave to the rate of flaring while the wave traverses the solar disk shows no increase in the number of flares due to the EIT wave. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, SM&A Corp E, Greenbelt, MD 20771 USA. RP Thompson, BJ (reprint author), NASA, Goddard Space Flight Ctr, SM&A Corp E, Mail Code 682-3, Greenbelt, MD 20771 USA. RI Thompson, Barbara/C-9429-2012 NR 33 TC 20 Z9 20 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD NOV PY 2000 VL 62 IS 16 BP 1449 EP 1455 DI 10.1016/S1364-6826(00)00085-7 PG 7 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 377PK UT WOS:000165521900005 ER PT J AU Gopalswamy, N Thompson, BJ AF Gopalswamy, N Thompson, BJ TI Early life of coronal mass ejections SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT IUGG/IAGA General Assembly CY JUL, 1999 CL UNIV BIRMINGHAM, BIRMINGHAM, ENGLAND SP IUGG, IAGA, Sci Comm Solar Terrestrial Phys HO UNIV BIRMINGHAM DE Coronal mass ejections; Coronal dimming; non-radial propagation; Photospheric magnetic field changes ID LASCO OBSERVATIONS; X-RAY; EIT; RADIO AB Coronal mass ejections (CMEs) are large-scale magnetized plasma structures ejected from closed magnetic field regions of the Sun. White light coronagraphic observations from ground and space have provided extensive information on CMEs in the outer corona. However, our understanding of the solar origin and early life of CMEs is still in an elementary stage because of lack of adequate observations. Recent space missions such as Yohkoh and Solar and Heliospheric Observatory (SOHO), and ground-based radioheliographs at Nobeyama and Nancay have accumulated a wealth of information on the manifestations of CMEs near the solar surface. We review some of these observations in an attempt to relate them to what we already know about CMEs. Our discussion relies heavily on non-coronagraphic data combined with coronagraphic data. Specifically, we discuss the following aspects of CMEs: (i) coronal dimming and global disk signatures, (ii) non-radial propagation during the early phase, (iii) Photospheric magnetic field changes during CMEs, and (iv) acceleration of fast CMEs. The relative positions and evolution of coronal dimming, arcade formation, prominence eruption will be discussed using specific events. The magnitude and spatial extent of CME acceleration may be an important parameter that distinguishes fast and slow CMEs. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Gaithersburg, MD 20878 USA. RP Gopalswamy, N (reprint author), NASA, Goddard Space Flight Ctr, Mailcode 682-3,Bldg 26,Room G-1, Gaithersburg, MD 20878 USA. RI Gopalswamy, Nat/D-3659-2012; Thompson, Barbara/C-9429-2012 NR 33 TC 57 Z9 58 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD NOV PY 2000 VL 62 IS 16 BP 1457 EP 1469 DI 10.1016/S1364-6826(00)00079-1 PG 13 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 377PK UT WOS:000165521900006 ER PT J AU Delannee, C AF Delannee, C TI Magnetic flux rope ejection: observation at 304 angstrom and comparison with recent models SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT IUGG/IAGA General Assembly CY JUL, 1999 CL UNIV BIRMINGHAM, BIRMINGHAM, ENGLAND SP IUGG, IAGA, Sci Comm Solar Terrestrial Phys HO UNIV BIRMINGHAM DE solar activity ID X-RAY; EIT; PROMINENCES; LASCO AB With one example of a coronal mass ejection observed with SOHO/EIT and LASCO we demonstrate the main characteristic of this kind of event: its flux rope nature. These events are commonly responsible for magnetic clouds approaching the Earth. Near the solar surface, the different structures es expected during the ejection of a flux rope are observed: post flare loops located under the flux rope, a prominence lying at its lower part, a coronal void located at its upper part. Two additional structures are observed in coronal emission: a bright loop possibly located at the leading edge of the flux rope and a bright front located near the equator and moving along the solar limb. These structures may correspond to the compression of material while the fur rope expands. Finally, the deviation of these structures toward the equator is observed, providing the possible explanation of the discrepancy of the location of the activity in the low corona and in the high corona during the minimum of solar cycle activity. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, SOHO EAF, Greenbelt, MD 20771 USA. RP Delannee, C (reprint author), NASA, Goddard Space Flight Ctr, SOHO EAF, Mail Code 682-3,Bldg 26,Room G-1, Greenbelt, MD 20771 USA. NR 21 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD NOV PY 2000 VL 62 IS 16 BP 1471 EP 1478 DI 10.1016/S1364-6826(00)00076-6 PG 8 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 377PK UT WOS:000165521900007 ER PT J AU Breen, AR Thompson, BJ Kojima, M Biesecker, DA Canals, A Fallows, RA Linker, JA Lazarus, AJ Lecinski, A Mikic, Z Moran, PJ Williams, PJS AF Breen, AR Thompson, BJ Kojima, M Biesecker, DA Canals, A Fallows, RA Linker, JA Lazarus, AJ Lecinski, A Mikic, Z Moran, PJ Williams, PJS TI Measurements of the solar wind over a wide range of heliocentric distances - a comparison of results from the first three, Whole Sun Months SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT IUGG/IAGA General Assembly CY JUL, 1999 CL UNIV BIRMINGHAM, BIRMINGHAM, ENGLAND SP IUGG, IAGA, Sci Comm Solar Terrestrial Phys HO UNIV BIRMINGHAM DE solar wind; solar cycle; interplanetary scintillation ID INTERPLANETARY SCINTILLATION OBSERVATIONS; CORONAL STRUCTURE; MONTH CAMPAIGN; VELOCITY; EISCAT; EVOLUTION; LATITUDE AB Go-ordinated observations of the Sun and inner heliosphere using a large number of space- and ground-based instruments were carried out in August-September 1996, August 1998 and August-September 1999 as the first, second and third Whole Sun Months. These observations provided unprecedented cover of the Sun and inner heliosphere at solar minimum (1996) and during the rising phase of the new solar cycle (1998, 1999). In this paper we review the observations made during the three Whole Sun Months and consider the changes in the large-scale structure of the heliosphere seen over the four years. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Wales, Solar Phys Grp, Aberystwyth SY23 3B2, Ceredigion, Wales. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Nagoya Univ, Solar Terr Environm Lab, Nagoya, Aichi, Japan. SM&A Corp E, Vienna, VA USA. Sci Applicat Int Corp, San Diego, CA 92121 USA. MIT, Cambridge, MA 02139 USA. UCAR, High Altitude Observ, Boulder, CO USA. RP Breen, AR (reprint author), Univ Wales, Solar Phys Grp, Aberystwyth SY23 3B2, Ceredigion, Wales. RI Thompson, Barbara/C-9429-2012 NR 36 TC 9 Z9 9 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1364-6826 J9 J ATMOS SOL-TERR PHY JI J. Atmos. Sol.-Terr. Phys. PD NOV PY 2000 VL 62 IS 16 BP 1527 EP 1543 DI 10.1016/S1364-6826(00)00090-0 PG 17 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 377PK UT WOS:000165521900013 ER PT J AU Ferguson, FT Heist, RH Nuth, JA AF Ferguson, FT Heist, RH Nuth, JA TI Vapor transport within the thermal diffusion cloud chamber SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID HOMOGENEOUS NUCLEATION; 2-DIMENSIONAL TRANSPORT; SUPERSATURATED VAPOR; BACKGROUND GASES; CONDENSATION; OPERATION; TUBE AB A review of two different, one-dimensional models of the vapor transport within the thermal diffusion cloud chamber (TDCC) is presented. In one case the assumption is made that there are no convective fluxes within the chamber and that heat and mass transport occur by diffusion only. Although in this model there are no restrictions on the transport of the two components within the chamber, the assumption of no velocities within the chamber results in an incorrect flux boundary condition for the background, carrier gas. The second model is based on the typical, stagnant background gas assumption and the equations of this model closely follow those of the classical Stefan tube problem in which there is transport of a volatile species through a noncondensible, carrier gas. Unfortunately, this model of the TDCC also suffers from the same inconsistencies as noted by several researchers for the Stefan tube. When the convective contributions to the flux are low in the stagnant background gas model, the two models give reasonably close results. For more convective situations, the supersaturation results can differ by more than 50%. One interesting feature of the zero velocity model is that it predicts a change in the supersaturation profile with pressure, whereas no pressure dependence is predicted with the stagnant background gas model. Unfortunately, the direction of this pressure change is opposite to that seen in experimental observations. (C) 2000 American Institute of Physics. [S0021-9606(00)50741-7]. C1 Catholic Univ Amer, Dept Chem, Washington, DC 20064 USA. Manhattan Coll, Dept Chem Engn, Riverdale, NY 10471 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ferguson, FT (reprint author), Catholic Univ Amer, Dept Chem, Washington, DC 20064 USA. RI Ferguson, Frank/C-9493-2012; Nuth, Joseph/E-7085-2012 NR 21 TC 4 Z9 4 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD NOV 1 PY 2000 VL 113 IS 17 BP 7398 EP 7405 DI 10.1063/1.1312381 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 368TD UT WOS:000090132900039 ER PT J AU Zhu, S Su, CH Lehoczky, SL Harris, MT Callahan, MJ McCarty, P George, MA AF Zhu, S Su, CH Lehoczky, SL Harris, MT Callahan, MJ McCarty, P George, MA TI Polarity effects of substrate surface in homoepitaxial ZnO film growth SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE ZnO crystal; epitaxial growth; structure; AFM ID SAPPHIRE AB Epitaxial ZnO films were grown on two polar surfaces (O-surface and Zn-surface) of (0001) ZnO single-crystal substrates using off-axis magnetron sputtering deposition. It was found that the two polar ZnO surfaces have different surface structure and morphology, which strongly influence epitaxial film growth. An interesting result shows that high-temperature annealing of ZnO single crystals will improve the surface structure on the O-terminated surface rather than the opposite surface. The morphology and structure of homoepitaxial films grown on the ZnO substrates were different from heteroepitaxial films grown on the Al2O3. The measurements of low-angle incident X-ray diffraction and atomic force microscopy of ZnO films indicate that the O-terminated surface is better for ZnO epitaxial film growth. (C) 2000 Published by Elsevier Science B.V. C1 NASA, George C Marshall Space Flight Ctr, Space Sci Lab, USRA SD47, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Sci Directorate, Huntsville, AL 35812 USA. SNHX, AFRL, Sensors Directorate, Hanscom AFB, MA 01731 USA. Univ Alabama, Dept Chem, Huntsville, AL 35899 USA. RP Zhu, S (reprint author), NASA, George C Marshall Space Flight Ctr, Space Sci Lab, USRA SD47, Huntsville, AL 35812 USA. NR 16 TC 16 Z9 17 U1 1 U2 8 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD NOV PY 2000 VL 219 IS 4 BP 361 EP 367 DI 10.1016/S0022-0248(00)00726-0 PG 7 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 369XD UT WOS:000165092300006 ER PT J AU Bishop, RL Earle, GD Herrero, FA Bateman, TT AF Bishop, RL Earle, GD Herrero, FA Bateman, TT TI Observations of an intermediate layer during the Coqui II campaign SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID NEUTRAL WIND; SPORADIC-E; ATMOSPHERE; LATITUDES; REGION AB NASA sounding rocket 21.114, launched March 7, 1998, during the Coqui II campaign, provided neutral wind and plasma density measurements of a weak intermediate layer. The layer was centered near 140 km and had an approximate peak plasma density of 2200 cm(-3). The measured winds were typically less than 40 m s(-1), in agreement with wind shear formation theory and coincident density observations. The data obtained during the flight allow us to explore the plasma density structure and wind field morphology of the intermediate layer. Coupled with simultaneous data from Arecibo Observatory, the upleg and downleg density profiles provide three spatially separated measurements that enable the first detailed investigation of the horizontal extent and variation of an intermediate layer. C1 Sci Applicat Int Corp, Mclean, VA 22102 USA. Univ Texas, William B Hanson Ctr Space Sci, Richardson, TX 75083 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Bishop, RL (reprint author), Sci Applicat Int Corp, Mclean, VA 22102 USA. NR 26 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2000 VL 105 IS A11 BP 24963 EP 24971 DI 10.1029/1999JA000453 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YX UT WOS:000165096300008 ER PT J AU Smets, R AF Smets, R TI Charged particle dynamics in a tangential discontinuity SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RECONNECTION FIELD GEOMETRY; MAGNETOPAUSE CURRENT LAYER; PITCH-ANGLE SCATTERING; MAGNETIC-FIELD; NONLINEAR DYNAMICS; ENERGETIC PROTONS; PLASMA SHEET; MAGNETOTAIL; ORBITS; DISTRIBUTIONS AB We investigate the regularity of particle motion in a magnetopause-like magnetic field topology for a southward interplanetary magnetic field case. For that issue, a rotation of 180 degrees of the magnetic field direction through the magnetopause is considered, while its total magnitude remains constant. Our main interest is to emphasize the different dynamical regimes for charged particles when their Larmor radii are of the order of the thickness of the magnetic field reversal layer. When the interface is a tangential discontinuity, it is shown that particle dynamics is regular, whereas the introduction of a small component of the magnetic field, normal to the interface, results ill weakly stochastic dynamics. A new parameter kappa (RL) is introduced to organize the charged particle dynamics. When kappa (RL) is greater than 1, particle motion is adiabatic, and when kappa (RL) is smaller than 1, particle motion is nonadiabatic, its magnetic moment being possibly either damped or unchanged when interacting with the discontinuity. Implications for the pitch angle distribution of a population interacting with such a tangential discontinuity will be discussed. C1 CNRS, Ctr Etud Environm Terr & Planetaires, F-78140 Velizy, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Smets, R (reprint author), CNRS, Ctr Etud Environm Terr & Planetaires, F-78140 Velizy, France. NR 34 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2000 VL 105 IS A11 BP 25009 EP 25020 DI 10.1029/1999JA000173 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YX UT WOS:000165096300011 ER PT J AU Ratkiewicz, R Barnes, A Spreiter, JR AF Ratkiewicz, R Barnes, A Spreiter, JR TI Local interstellar medium and modeling the heliosphere SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND INTERACTION; RADIAL IMF COMPONENT; MAGNETIC-FIELD; LATITUDINAL DEPENDENCE; TERMINATION SHOCK; FLOW DOWNSTREAM; HELIOPAUSE; SIMULATION; IMPRINT; PLASMA AB We use the best currently available estimates for interstellar parameters to update and expand the earlier study of Ratkiewicz et al. [1998]. We report (1) a more complete survey of the morphology of the heliosphere and the ways it may be modified by variation of external interstellar parameters, (2) a detailed classification of the several asymmetries and distortions associated with exterior field-flow obliquity, including cross sections of the three-dimensional structure in all three principal planes, (3) an analysis of the transition from supermagnetosonic to nearly transmagnetosonic flow, and (4) specific results for the heliosphere for the best current understanding of conditions in the local interstellar medium. C1 Ctr Space Res, PL-00716 Warsaw, Poland. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. Stanford Univ, Stanford, CA 94305 USA. RP Ratkiewicz, R (reprint author), Ctr Space Res, Bartycka 18A, PL-00716 Warsaw, Poland. EM roma@cbk.waw.pl; abarnes@mail.arc.nasa.gov NR 42 TC 30 Z9 30 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2000 VL 105 IS A11 BP 25021 EP 25031 DI 10.1029/1999JA005084 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YX UT WOS:000165096300012 ER PT J AU Suess, ST Poletto, G Romoli, M Neugebauer, N Goldstein, BE Simnett, G AF Suess, ST Poletto, G Romoli, M Neugebauer, N Goldstein, BE Simnett, G TI The May 1997 SOHO-Ulysses quadrature SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ULTRAVIOLET CORONAGRAPH SPECTROMETER; SOLAR-WIND; STRAY-LIGHT; UVCS/SOHO; STREAMER; REGIONS; MINIMUM; ORIGIN AB We present results from the May 1997 SOHO-Ulysses quadrature (SOHO-Sun-Ulysses angle=90 degrees), near sunspot minimum. Ulysses was at 5.1 AU, 10 degrees north of the solar equator, and off the east limb. It was also at the very northern edge of the streamer belt, Nevertheless, the Solar Wind Observations Over the Poles of the Sun instrument (SWOOPS) detected only slow, unusually smooth wind and there was no direct evidence of fast wind from the northern polar coronal hole or of mixing with fast wind. The Large-Angle and Spectrometric Coronagraph (LASCO) images show that the streamer belt at 10 degreesN was narrow and sharp at the beginning and end of the 2 week observation interval. but broadened in the middle. A related change in density, but not flow speed, occurred at Ulysses. Under these conditions it was possible to show that densities derived from the Ultraviolet Coronagraph Spectrometer (UVCS) in the lower corona are closely related to those in the solar wind, both over quiet intervals and in transient events on the limb. Density and velocity in one small transient observed by both LASCO and UVCS are analyzed in detail. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Florence, Dept Astron, I-50125 Florence, Italy. Osservatorio Astrofis Arcetri, I-50125 Florence, Italy. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Birmingham, Sch Phys & Astron, Dept Space Res, Birmingham B15 2TT, W Midlands, England. RP Suess, ST (reprint author), NASA, George C Marshall Space Flight Ctr, MS SD50, Huntsville, AL 35812 USA. RI Romoli, Marco/H-6859-2012 NR 30 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2000 VL 105 IS A11 BP 25033 EP 25051 DI 10.1029/2000JA000044 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YX UT WOS:000165096300013 ER PT J AU Russell, CT Wang, YL Raeder, J Tokar, RL Smith, CW Ogilvie, KW Lazarus, AJ Lepping, RP Szabo, A Kawano, H Mukai, T Savin, S Yermolaev, YI Zhou, XY Tsurutani, BT AF Russell, CT Wang, YL Raeder, J Tokar, RL Smith, CW Ogilvie, KW Lazarus, AJ Lepping, RP Szabo, A Kawano, H Mukai, T Savin, S Yermolaev, YI Zhou, XY Tsurutani, BT TI The interplanetary shock of September 24, 1998: Arrival at Earth SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID IONOSPHERIC MASS EJECTION; MAGNETIC-FIELD; SPACECRAFT; MAGNETOSPHERE; SATELLITE; WAVES AB At close to 2345 UT on September 24, 1998, the magnetosphere was suddenly compressed by the passage of an interplanetary shock. In order to properly interpret the magnetospheric events triggered by the arrival of this shock, we calculate the orientation of the shock, its velocity, and its estimated time of arrival at the nose of the magnetosphere. Our best fit shock normal has an orientation of (-0.981 -0.157 -0.112) in solar ecliptic coordinates, a speed of 769 km/s, and an arrival time of 2344:19 at the magnetopause at 10 R-E. Since measurements of the solar wind and interplanetary magnetic field are available from multiple spacecraft, we can compare several different techniques of shock-normal determination. Of the single spacecraft techniques the magnetic coplanarity solution is most accurate and the mixed mode solution is of lesser accuracy. Uncertainty in the timing and location of the IMP 8 spacecraft limits the accuracy of solutions using the time of arrival at the position of IMP 8. C1 Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ Delaware, Bartol Res Inst, Newark, DE 19716 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. MIT, Space Res Ctr, Cambridge, MA 02139 USA. Kyushu Univ 33, Dept Earth & Planetary Sci, Higashi Ku, Fukuoka 8128581, Japan. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. Russian Acad Sci, Space Res Inst, Moscow 117810, Russia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Chinese Acad Sci, Inst Geophys, Beijing, Peoples R China. RP Russell, CT (reprint author), Univ Calif Los Angeles, Inst Geophys & Planetary Phys, 3845 Slichter Hall,405 Hilgard Ave, Los Angeles, CA 90095 USA. NR 26 TC 37 Z9 38 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2000 VL 105 IS A11 BP 25143 EP 25154 DI 10.1029/2000JA900070 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YX UT WOS:000165096300020 ER PT J AU Sibeck, DG Kudela, K Lepping, RP Lin, R Nemecek, Z Nozdrachev, MN Phan, TD Prech, L Safrankova, J Singer, H Yermolaev, Y AF Sibeck, DG Kudela, K Lepping, RP Lin, R Nemecek, Z Nozdrachev, MN Phan, TD Prech, L Safrankova, J Singer, H Yermolaev, Y TI Magnetopause motion driven by interplanetary magnetic field variations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EARTHS BOW SHOCK; UPSTREAM PRESSURE VARIATIONS; SOLAR-WIND; MAGNETOSPHERIC RESPONSE; 3-DIMENSIONAL PLASMA; DIAMAGNETIC CAVITIES; FLUX; HOT; WAVES AB We use previously reported observations of hot flow anomalies (HFAs) and foreshock cavities to predict the characteristics of corresponding features in the dayside magnetosheath, at the magnetopause, and in the outer dayside magnetosphere. We compare these predictions with Interball 1, Magion 4, and GOES 8/GOES 9 observations of magnetopause motion on the dusk flank of the magnetosphere from 1800 UT on January 17 to 0200 UT on January 18, 1996. As the model predicts, strong (factor of 2 or more) density enhancements bound regions of depressed magnetosheath densities and/or outward magnetopause displacements. During the most prominent event, the geosynchronous spacecraft observe an interval of depressed magnetospheric magnetic field strength bounded by two enhancements. Simultaneous Wind observations indicate that the intervals of depressed magnetosheath densities and outward magnetopause displacements correspond to periods in which the east/west (By) component of the interplanetary magnetic field (IMF) decreases to values near zero rather than to variations in the solar wind dynamic pressure, the north/south component of the IMF, or the IMF cone angle. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Inst Expt Phys, Kosice 04353, Slovakia. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Charles Univ, Dept Elect & Vacuum Phys, CR-18000 Prague, Czech Republic. Moscow Space Res Inst, Moscow 117810, Russia. NOAA, Space Environm Lab, Boulder, CO 80303 USA. RP Sibeck, DG (reprint author), Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA. RI Sibeck, David/D-4424-2012 NR 32 TC 30 Z9 30 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2000 VL 105 IS A11 BP 25155 EP 25169 DI 10.1029/2000JA900109 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YX UT WOS:000165096300021 ER PT J AU Delcourt, DC Moore, TE Giles, BL Fok, MC AF Delcourt, DC Moore, TE Giles, BL Fok, MC TI Quantitative modeling of modulated ion injections observed by Polar-Thermal Ion Dynamics Experiment in the cusp region SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FLUX-TRANSFER EVENTS; PLASMA MANTLE; MAGNETOPAUSE RECONNECTION; IONOSPHERIC SIGNATURES; EARTHS MAGNETOPAUSE; PARTICLE MOTION; LOW-ALTITUDE; SHEET; MAGNETOSPHERE; PRECIPITATION AB On May 13, 1996, as the Polar spacecraft was traveling at high invariant latitudes (similar to 78 degrees -79 degrees) in the prenoon sector (similar to 1050 magnetic local time), the Thermal Ion Dynamics Experiment on board recorded successive injections of protons with clear energy-time dispersion. These dispersion structures spread over several minutes and extend from several hundreds of eV down to a few tens of eV. During this pass, simultaneous measurements from the Wind spacecraft revealed little variation of the solar wind dynamical pressure but a gradual turning of the interplanetary magnetic field (IMF) from an essentially dawn-to-dusk orientation (i.e,, predominant positive By component and slighly negative B-Z) to a north-to-south one (predominant negative B-Z). We show that the observed injections result from magnetosheath particle entry at higher and higher latitudes in the dawn sector. Using test particle calculations in a simple model of reconnected interplanetary and magnetospheric field, we show that the injection modulation likely follows fi-om changes in the dynamical regime experienced by the ions upon traversal of the magnetopause current sheet. That is, as the IMF gradually rotates, the time-varying B-Y and B-Z lead to changes in the adiabaticity parameter kappa in the region of entry and affect particle access to the Polar location. In the morning sector where magnetosheath plasma accelerates downtail, such an access to the inner magnetosphere requires magnetic moment damping and is thus favored during nonadiabatic episodes. The flux variations obtained numerically are in qualitative agreement with those observed, both in terms of characteristic energy and overall time evolution. This supports our interpretation of the modulated ion injections in terms of intermittent nonadiabatic entry from the magnetosheath followed by time of flight dispersion between the magnetopause and the spacecraft. C1 Ctr Etud Environm Terrestre & Planetaires, CNRS, F-94107 St Maur Des Fosses, France. NASA, Goddard Space Flight Ctr, Interplanetary Phys Branch, Greenbelt, MD 20771 USA. RP Delcourt, DC (reprint author), Ctr Etud Environm Terrestre & Planetaires, CNRS, 4 Ave Neptune, F-94107 St Maur Des Fosses, France. RI Moore, Thomas/D-4675-2012; Fok, Mei-Ching/D-1626-2012 OI Moore, Thomas/0000-0002-3150-1137; NR 36 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD NOV 1 PY 2000 VL 105 IS A11 BP 25191 EP 25203 DI 10.1029/2000JA000034 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YX UT WOS:000165096300024 ER PT J AU Machida, S Ieda, A Mukai, T Saito, Y Nishida, A AF Machida, S Ieda, A Mukai, T Saito, Y Nishida, A TI Statistical visualization of Earth's magnetotail during substorms by means of multidimensional superposed epoch analysis with Geotail data SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID LOW-ENERGY PARTICLE; DISTANT MAGNETOTAIL; EVOLUTION; ISEE-3; PLASMOIDS; VELOCITY; TAIL AB A multidimensional superposed epoch analysis of plasma and magnetic field data from the Geotail spacecraft; was used to visualize the time evolution of plasmoids in the Earth's magnetotail statistically. The substorm events were identified by Pi2 events at midlatitude ground stations when Geotail was in the downtail region from -30 R-E to -200 R-E. Plasma density, velocity, temperature, and magnetic field data were sorted and analyzed according to the Pi2 onset time. We selected 156 substorm events that were either a single onset or the first onset of multiple onsets. In the statistical visualization, we found that plasma acceleration does not take place in a small region around X similar to -30 R-E, but occurs in a more widely spread region extending from X similar to -30 R-E down to X similar to -90 R-E. The spatial structure of the plasmoid is characterized by a bilatitudinal structure where the fast plasma how in the plasma sheet boundary stretches from the equator and a relatively slow plasma sheet flow is encountered with preexisting plasma sheet populations. Finite B-y fields are created in the inner plasma sheet boundary, and the total pressure is enhanced inside the plasmoid. The evolution of the plasma and magnetic fields as well as the deduced parameters, such as the number flux of plasma or energy fluxes, agreed well with a magnetic reconnection model. C1 Kyoto Univ, Grad Sch Sci, Dept Geophys, Kyoto 6068502, Japan. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. RP Machida, S (reprint author), Kyoto Univ, Grad Sch Sci, Dept Geophys, Kyoto 6068502, Japan. NR 20 TC 18 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 NOV 1 PY 2000 VL 105 IS A11 BP 25291 EP 25303 DI 10.1029/2000JA900064 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 369YX UT WOS:000165096300030 ER PT J AU Shtessel, Y Hall, C Jackson, M AF Shtessel, Y Hall, C Jackson, M TI Reusable launch vehicle control in multiple-time-scale sliding modes SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID VARIABLE STRUCTURE CONTROL AB A reusable launch vehicle control problem during ascent is addressed via multiple-time-scale continuous sliding mode control. The proposed sliding mode controller utilizes a two-loop structure and provides robust, decoupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of bounded external disturbances and plant uncertainties. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, decoupled, homogeneous, and vector-valued differential equations with desired eigenvalues. Overall stability of a two-loop control system is addressed. An optimal control allocation algorithm is designed that allocates torque commands into end-effector deflection commands, which are executed by the actuators. The dual-time-scale sliding mode controller was designed for the X-33 technology demonstration suborbital launch vehicle in the launch mode. Simulation results show that the designed controller provides robust, accurate, decoupled tracking of the orientation angle command profiles in the presence of external disturbances and vehicle inertia uncertainties. The robust controller is designed to significantly reduce the time and cost associated with dying to new orbits, with new payloads, and with modified vehicles. C1 Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Space Transportat Directorate, Vehicle & Syst Dev Dept, Huntsville, AL 35812 USA. RP Shtessel, Y (reprint author), Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA. NR 12 TC 49 Z9 65 U1 0 U2 8 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 2000 VL 23 IS 6 BP 1013 EP 1020 DI 10.2514/2.4669 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 372HK UT WOS:000165228100006 ER PT J AU Markley, FL Reynolds, RG AF Markley, FL Reynolds, RG TI Analytic steady-state accuracy of a spacecraft attitude estimator SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article C1 NASA, Goddard Space Flight Ctr, Guidance Navigat & Control Ctr, Greenbelt, MD 20771 USA. RP Markley, FL (reprint author), NASA, Goddard Space Flight Ctr, Guidance Navigat & Control Ctr, Greenbelt, MD 20771 USA. NR 6 TC 10 Z9 11 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 2000 VL 23 IS 6 BP 1065 EP 1067 DI 10.2514/2.4648 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 372HK UT WOS:000165228100012 ER PT J AU Bartels, RE Schuster, DM AF Bartels, RE Schuster, DM TI Comparison of two Navier-Stokes methods with benchmark active control technology experiments SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Two commonly used three-dimensional compressible Navier-Stokes codes are applied to select test cases from an experimental data set on a model known as the Benchmark Active Control Technology (BACT) wing. The BACT test provides data for the validation of aerodynamic, aeroelastic, and active aeroelastic control simulation codes. An overview will be presented of the two Navier-stokes aeroelastic codes currently being used In an analysis of that data. A collection or results obtained by the two methods will be compared with the BACT experimental data for a wing with a statically deflected spoiler and statically and dynamically deflected aileron. Both methods employ structured computational fluid dynamics flow solvers and continuous surface modeling for the computation of complex moving control surface geometry. Motivation for this work is the development of an integrated computational aeroelasticity and active! control simulation capability for the transonic flight regime and validation of that capability using the BACT wing data. C1 NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23681 USA. RP Bartels, RE (reprint author), NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23681 USA. NR 9 TC 4 Z9 5 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 2000 VL 23 IS 6 BP 1094 EP 1099 DI 10.2514/2.4660 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 372HK UT WOS:000165228100022 ER PT J AU Scott, RC Pado, LE AF Scott, RC Pado, LE TI Active control of wind-tunnel model aeroelastic response using neural networks SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Under a joint research and development effort conducted by NASA and The Boeing Company (formerly McDonnell Douglas), three neural-network-based control systems were developed and tested. The control systems were experimentally evaluated using a transonic wind-tunnel model in the NASA Langley Research Center Transonic Dynamics Tunnel, One system used a neural network to schedule Butter suppression control laws, another employed a neural network in a predictive control scheme, and the third employed a neural network in an inverse model control scheme. All three of these control schemes successfully suppressed flutter to or near the limits of the testing apparatus and represent the first experimental applications of neural networks to Butter suppression. The findings of this project are summarized. C1 NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23665 USA. Boeing Co, Informat Syst Technol Smart Struct & Syst, St Louis, MO 63166 USA. RP Scott, RC (reprint author), NASA, Langley Res Ctr, Aeroelast Branch, Hampton, VA 23665 USA. NR 23 TC 39 Z9 40 U1 0 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD NOV-DEC PY 2000 VL 23 IS 6 BP 1100 EP 1108 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 372HK UT WOS:000165228100023 ER PT J AU Hwang, PA Wang, DW Walsh, EJ Krabill, WB Swift, RN AF Hwang, PA Wang, DW Walsh, EJ Krabill, WB Swift, RN TI Airborne measurements of the wavenumber spectra of ocean surface waves. Part I: Spectral slope and dimensionless spectral coefficient SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID GREENLAND ICE-SHEET; SHORT WATER-WAVES; DIRECTIONAL SPECTRUM; LASER ALTIMETRY; CLOVERLEAF BUOY; NUMBER SPECTRA; WIND-WAVES; FETCH; EVOLUTION; JONSWAP AB An airborne scanning lidar system acquires 3D spatial topography of ocean surface waves. From the spatial data, wavenumber spectra are computed directly. The spectral analyses of two distinctively different wave fields are presented. The first one is a quasi-steady wave field under active wind generation, and the second one is a decaying wave field following a slackening of the wind field. Subtle differences in different representations of the one-dimensional spectrum (omnidirectional, marginal, and traverse) are illustrated. The spectral properties in terms of the dimensionless spectral coefficient and spectral slope in the equilibrium range are investigated using the wavenumber spectra directly computed from the 3D topography of the ocean surface. The results are in excellent agreement with existing data. The rapid data acquisition afforded by an airborne system provides an enhanced capability for studying the spatial variation of a wave field with minimal temporal changes in the environmental forcing conditions. The data of the 3D surface topography are also ideal for the quantitative investigation of the directional properties of a random wave field. C1 USN, Res Lab, Div Oceanog, Stennis Space Ctr, MS 39529 USA. NASA, Goddard Space Flight Ctr, WFF, Wallops Island, VA 23337 USA. EG&G, WFF, Wallops Island, VA USA. NOAA, ETL, Boulder, CO USA. RP Hwang, PA (reprint author), USN, Res Lab, Div Oceanog, Stennis Space Ctr, MS 39529 USA. NR 37 TC 73 Z9 74 U1 0 U2 8 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 NOV PY 2000 VL 30 IS 11 BP 2753 EP 2767 DI 10.1175/1520-0485(2001)031<2753:AMOTWS>2.0.CO;2 PG 15 WC Oceanography SC Oceanography GA 378MQ UT WOS:000165588500008 ER PT J AU Hwang, PA Wang, DW Walsh, EJ Krabill, WB Swift, RN AF Hwang, PA Wang, DW Walsh, EJ Krabill, WB Swift, RN TI Airborne measurements of the wavenumber spectra of ocean surface waves. Part II: Directional distribution SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID GREENLAND ICE-SHEET; WIND-WAVES; LASER ALTIMETRY; FETCH; EVOLUTION AB An airborne scanning lidar system acquires three-dimensional (3D) spatial topography of ocean surface waves. From the spatial data, wavenumber spectra are computed directly. The spectral properties in terms bf the spectral slope and dimensionless spectral coefficient have been verified to be in very good agreement with existing data. One of the unique features of the 3D spatial data is its exceptional directional resolution. Directional properties such as the wavenumber dependence of the directional spreading function and the evolution of bimodal development are investigated with these high-resolution, phase-resolving spatial measurements. Equations for the spreading parameters, the lobe angle, and the lobe ratio are established from the airborne scanning lidar datasets. Fourier decomposition of the measured directional distribution is presented. The directional parameters can be represented by a small number (4) of the Fourier components. The measured directional distributions are compared with numerical experiments of nonlinear wave simulations to explore the functional form of the dissipation source term. C1 USN, Res Lab, Div Oceanog, Stennis Space Ctr, MS 39529 USA. NASA, Goddard Space Flight Ctr, WFF, Wallops Island, VA 23337 USA. EG&G, WFF, Wallops Island, VA USA. NOAA, ETL, Boulder, CO USA. RP Hwang, PA (reprint author), USN, Res Lab, Div Oceanog, Stennis Space Ctr, MS 39529 USA. NR 26 TC 49 Z9 50 U1 0 U2 4 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 NOV PY 2000 VL 30 IS 11 BP 2768 EP 2787 DI 10.1175/1520-0485(2001)031<2768:AMOTWS>2.0.CO;2 PG 20 WC Oceanography SC Oceanography GA 378MQ UT WOS:000165588500009 ER PT J AU Gostowski, RC Bailey, T Bonner, SD Emrich, EE Steelman, SL AF Gostowski, RC Bailey, T Bonner, SD Emrich, EE Steelman, SL TI Steric hindrance effects on bimolecular coupling rate constants of carbon-centered radicals SO JOURNAL OF PHYSICAL ORGANIC CHEMISTRY LA English DT Article DE radicals; bimolecular coupling; steric hindrance; anisiotropy; kinetics; voltammetry ID BOND-DISSOCIATION ENERGIES; DIMETHYL-SULFOXIDE SOLUTION; DIFFUSION-CONTROLLED REACTIONS; C-H BONDS; ELECTRON-TRANSFER; CYCLIC VOLTAMMETRY; GAS-PHASE; N-H; CARBANIONS; STRENGTHS AB Carbon-centered radicals have historically been classified as either persistent or reactive in solution. Little attention has been given to finding a relationship between this reactivity and the steric hindrance of radicals. The bimolecular coupling rate constants of some aryl-substituted fluorenyl and xanthenyl radicals were determined utilizing fast-scan cyclic voltammetry and digital simulations. This rate constant was found to be attenuated from the diffusion-limited value as the twist of the aryl substituent increased; the twist was described by an appropriate dihedral angle (Theta). However, Theta was found to be insufficient to represent the steric shielding provided by the aryl groups. Instead, thickness parameters (Z) obtained from MOPAC RHF-PM3 calculations correlated well (R-2 = 0.954) with the coupling rate constants of the radicals considered. This parameter was taken as the greatest extent of the van der Waals surface in the area of the p-orbital holding the unpaired electron. Copyright (C) 2000 John Wiley & Sons. C1 Austin Peay State Univ, Dept Chem, Clarksville, TN 37044 USA. RP Gostowski, RC (reprint author), NASA, George C Marshall Space Flight Ctr, MSFC, ED36, Huntsville, AL 35812 USA. NR 53 TC 2 Z9 2 U1 2 U2 2 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 0894-3230 J9 J PHYS ORG CHEM JI J. Phys. Org. Chem. PD NOV PY 2000 VL 13 IS 11 BP 735 EP 739 DI 10.1002/1099-1395(200011)13:11<735::AID-POC310>3.0.CO;2-Z PG 5 WC Chemistry, Organic; Chemistry, Physical SC Chemistry GA 371VA UT WOS:000165198900010 ER PT J AU Kroll, JT Sowa, WA Samuelsen, GS Holdeman, JD AF Kroll, JT Sowa, WA Samuelsen, GS Holdeman, JD TI Optimization of orifice geometry for crossflow mixing in a cylindrical duct SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID MULTIPLE JETS; FLOW AB Mixing of gaseous jets in a crossflow has significant applications in combustion science and engineering, one example of which is the mixing zone of a rich-burn/quick-mix/lean-burn gas turbine combustor. A major design question is the jet orifice shape and jet orifice number that optimizes the mixing performance. To delineate the optimal orifice features for a given axial distance and momentum-flux ratio, a statistical design of experiments test matrix was established around three variables: the number of orifices, the orifice aspect ratio, and the orifice angle (in circumferential plane). A jet-to-mainstream momentum-flux ratio of 40 and a mass-flow ratio of 2.5 were selected as representative of a practical design. To yield an interpolating equation that predicts the mixing performance of orifice geometry combinations within the range of the test matrix parameters, a regression analysis was conducted on the data. The results reveal that 1) mixture uniformity is a nonlinear function of the number of orifices, the orifice aspect ratio, and the orifice angle and that 2) optimum mixing occurs when the mean jet trajectories are in the range of 0.30 < IR < 0.5 (where = R - r) at x/R = 1. At the optimum number of orifices, the difference between shallow-angled slots with large aspect ratios and round holes Is minimal and either geometry produces optimal mixing performance. C1 Univ Calif Irvine, Combust Lab, Dept Mech Aerosp & Environm Engn, Irvine, CA 92697 USA. NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Kroll, JT (reprint author), Univ Calif Irvine, Combust Lab, Dept Mech Aerosp & Environm Engn, Irvine, CA 92697 USA. NR 22 TC 14 Z9 14 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 2000 VL 16 IS 6 BP 929 EP 938 DI 10.2514/2.5669 PG 10 WC Engineering, Aerospace SC Engineering GA 374KR UT WOS:000165344800001 ER PT J AU Steffen, CJ Smith, TD Yungster, S Keller, DJ AF Steffen, CJ Smith, TD Yungster, S Keller, DJ TI Computational analysis for rocket-based combined-cycle systems during rocket-only operation SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID TURBULENCE MODEL; FLOWS AB A series of Reynolds-averaged Navier-Stokes calculations were employed to study the performance of rocket-based combined-cycle systems operating in an all-rocket mode. This parametric series of calculations were executed within a statistical framework, commonly known as design of experiments, The parametric design space included four geometric and two flowfield variables set at three levels each, for a total of 729 possible combinations, A D-optimal design strategy was selected. It required that only 36 separate computational fluid dynamics (CFD) solutions be performed to develop a full response surface model, which quantified the linear, bilinear, and curvilinear effects of the six experimental variables. The axisymmetric, Reynolds-averaged Navier-Stokes simulations were executed with the NPARC v3.0 code. The response used in the statistical analysis was created from I-sp efficiency data integrated from the 36 CFD simulations. The influence of turbulence modeling was analyzed by using both one- and two-equation models. Careful attention was also given to quantify the influence of mesh dependence, iterative convergence, and artificial viscosity upon the resulting statistical model. Thirteen statistically significant effects were observed to have an influence on rocket-based combined-cycle nozzle performance. It was apparent that the free-expansion process, directly downstream of the rocket nozzle, can influence the I-sp efficiency. Numerical schlieren images and particle traces have been used to further understand the physical phenomena behind several of the statistically significant results. C1 NASA, John H Glenn Res Ctr, Turbomachinery & Propuls Syst Div, Cleveland, OH 44135 USA. Real World Qual Syst Inc, Inst Computat Mech Propuls, Rocky River, OH USA. RP Steffen, CJ (reprint author), NASA, John H Glenn Res Ctr, Turbomachinery & Propuls Syst Div, Cleveland, OH 44135 USA. NR 28 TC 4 Z9 4 U1 3 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 2000 VL 16 IS 6 BP 1030 EP 1039 DI 10.2514/2.5673 PG 10 WC Engineering, Aerospace SC Engineering GA 374KR UT WOS:000165344800013 ER PT J AU Momoh, JA Zhu, JZ Dolce, JL AF Momoh, JA Zhu, JZ Dolce, JL TI Optimal allocation with network limitation for autonomous space power system SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A new approach is presented to congestion analysis and optimal load shedding for aerospace power systems. Optimal power Row, an analytic hierarchical process, and the Everett optimization method (Everett, II., Operations Research, Vol. 11, 1963, pp. 399-417) are employed for implementing this approach. several system performance indices are developed to evaluate the degree of system congestion for different operation Lime stages. These performance indites include a circuit overload index and a system voltage problem index obtained through the optimal power Row calculation. The congested system is alleviated by the available control such as load shedding. Therefore, the mathematical model of load shedding, in which the objective is a payoff function, is devised. The solution method of the model is the Everett method, generalized Lagrange multipliers. Detailed results art! given in the paper. C1 Howard Univ, Dept Elect Engn, Ctr Energy Syst & Control, Washington, DC 20059 USA. NASA, John H Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. RP Momoh, JA (reprint author), Howard Univ, Dept Elect Engn, Ctr Energy Syst & Control, Washington, DC 20059 USA. NR 9 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 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD NOV-DEC PY 2000 VL 16 IS 6 BP 1112 EP 1117 DI 10.2514/2.5685 PG 6 WC Engineering, Aerospace SC Engineering GA 374KR UT WOS:000165344800024 ER PT J AU Goorvitch, D AF Goorvitch, D TI Calculation of instrument functions SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID BAND AB The calculation of an accurate instrument function can be facilitated by choosing an appropriate representation space. Were I show that for a Fourier transform spectrometer the physical space is the best space to use in calculating an accurate instrument function. Several examples are calculated including the instrument function for a Fourier interferometer illuminated with uncollimated radiation with misaligned mirrors whose interferogram is apodized. Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. RP Goorvitch, D (reprint author), NASA, Ames Res Ctr, Div Space Sci, Mail Stop N245-6, Moffett Field, CA 94035 USA. NR 8 TC 2 Z9 2 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD NOV 1 PY 2000 VL 67 IS 3 BP 253 EP 257 DI 10.1016/S0022-4073(99)00231-9 PG 5 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 338LE UT WOS:000088420500006 ER PT J AU Ibrahim, M Sokolov, P Kerslake, T Tolbert, C AF Ibrahim, M Sokolov, P Kerslake, T Tolbert, C TI Experimental and computational investigations of phase change thermal energy storage canisters SO JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID PACKED-BED AB Two sets of experimental data for cylindrical canisters with thermal energy storage applications were examined in this paper: 1) Ground Experiments and 2) Space Experiments. A 2-D computational model was developed for unsteady hear transfer (conduction and radiation) with phase-change. The radiation heat transfer employed a finite volume method. The following was found in this study: 1) Ground Experiments, the convection heat transfer is equally important to that of the radiation hear transfer: Radiation heat transfer in the liquid is found to be more significant than that in the void; Including the radiation heat transfer in the liquid resulted in lower temperatures labour 15 K) and increased the melting time (about 10 min.); Generally, most of the heat flow takes place in the radial direction. 2) Space Experiments. Radiation hear transfer in the void is found to be more significant than that in the liquid (exactly the opposite to the Ground Experiments); Accordingly, the location and size of the void affects the performance considerably; Including the radiation hear transfer in the void resulted in lower temperatures (about 40 K). [S0199-6231(00)00304-X]. C1 Cleveland State Univ, Cleveland, OH 44115 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Ibrahim, M (reprint author), Cleveland State Univ, Cleveland, OH 44115 USA. NR 17 TC 8 Z9 8 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0199-6231 J9 J SOL ENERG-T ASME JI J. Sol. Energy Eng. Trans.-ASME PD NOV PY 2000 VL 122 IS 4 BP 176 EP 182 DI 10.1115/1.1330726 PG 7 WC Energy & Fuels; Engineering, Mechanical SC Energy & Fuels; Engineering GA 404NC UT WOS:000167105800003 ER PT J AU Palmer, G Chen, YK Papadopoulos, P Tauber, M AF Palmer, G Chen, YK Papadopoulos, P Tauber, M TI Reassessment of effect of dust erosion on heatshield of Mars entry vehicle SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID STORMS AB A computation is performed to assess the surface erosion due to dust particle impact for the Mars 2001 Lander vehicle. A previous study on a Mars aerocapture vehicle indicated that a significant amount of dust erosion would take place. The present calculation uses a three-dimensional NavierStokes flow solver and a more sophisticated atmospheric dust model to provide inputs for the dust erosion algorithm. The new dust model predicts a lower mass mixing ratio and a smaller average dust particle size than previous models. The computed surface erosion on the Mars 2001 Lander vehicle is found to be negligible. C1 NASA, Ames Res Ctr, Reacting Flow Environm Branch, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Thermal Protect Branch, Moffett Field, CA 94035 USA. Eloret Corp, Reacting Flow Environm Branch, Sunnyvale, CA 94087 USA. RP Palmer, G (reprint author), NASA, Ames Res Ctr, Reacting Flow Environm Branch, Moffett Field, CA 94035 USA. NR 21 TC 4 Z9 4 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2000 VL 37 IS 6 BP 747 EP 752 DI 10.2514/2.3646 PG 6 WC Engineering, Aerospace SC Engineering GA 382PZ UT WOS:000165832600005 ER PT J AU Woodard, SE AF Woodard, SE TI Upper atmosphere research satellite in-flight dynamics study: Lessons learned SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SPACECRAFT AB The lessons learned from investigating the Upper Atmosphere Research Satellite (UARS) in-night dynamics are summarized. Key to the success of the study was the application of knowledge discovery in database techniques. The isolation of disturbances mas critical to identifying the effect of individual disturbances on the spacecraft. Numerous types of data sere examined for spatial and frequency correlation as a means of discovering hidden knowledge of the dynamic behavior of the spacecraft and its instruments, Two in-flight dynamics experiments were conducted on UARS to provide the investigation with cases of isolated and combined instrument and environmental disturbances that were not attainable during the normal operation of the spacecraft. Flight data from the experiments were augmented with data collected from the first 737 days after launch. This study identified many disturbances that greatly impacted the spacecraft line-of-sight pointing but were ignored from prelaunch analysis. The spacecraft attitude response was significantly influenced by the thermal elastic bending of the solar array the solar array gear drive, orientation of the solar array, and instrument motion. These disturbances can now be included in a knowledge base for future prelaunch analysis. C1 NASA, Langley Res Ctr, Struct Dynam Branch, Hampton, VA 23681 USA. RP Woodard, SE (reprint author), NASA, Langley Res Ctr, Struct Dynam Branch, Hampton, VA 23681 USA. NR 15 TC 2 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD NOV-DEC PY 2000 VL 37 IS 6 BP 794 EP 800 DI 10.2514/2.3637 PG 7 WC Engineering, Aerospace SC Engineering GA 382PZ UT WOS:000165832600012 ER PT J AU Holzer, M Hall, TM AF Holzer, M Hall, TM TI Transit-time and tracer-age distributions in geophysical flows SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID GENERAL-CIRCULATION MODEL; STRATOSPHERIC TRANSPORT; CARBON-DIOXIDE; TROPOSPHERE; VENTILATION; CLIMATE; RATES; CO2 AB Transport in the atmosphere and in the ocean is the result of the complex action of time-dependent and often highly turbulent flow. A useful diagnostic that summarizes the rate at which fluid elements are transported from some region to a point (or the reverse) via a multiplicity of pathways and mechanisms is the probability density function (pdf) of transit times. The first moment of this pdf, often referred to as "mean age," has become an important transport diagnostic commonly used by the observational community. This paper explores how to probe the flow with passive tracers to extract transit-time pdf's. As a foundation, the literal "tracer age" is defined as the elapsed time since tracer was injected into the flow, and the corresponding tracer-age distribution, Z, as the fractional tracer mass in a given interval of tracer age. The distribution, Z, has concrete physical interpretation for arbitrary sources, but is only equivalent to a tracer-independent transit-time pdf of the flow in special cases. The transit-time pdf is a propagator, G', of boundary conditions (the "age spectrum" of T. M. Hall and R. A. Plumb) applied over a control surface, Omega. The propagator G' is shown to be the flux into Omega resulting from a unit mass injected into the time-reversed how. Through explicit construction of the transit-time pdf using the concept of tracer age, the special cases for which Z and G' coincide are established. This allows a direct physical demonstration of S', and its adjoint G'dagger, as the pdf's of transit times since fluid at point r had last contact with Omega, and until fluid at r will have first contact with Omega, respectively. In the limit as Omega is shrunk to a point, point-to-point transit-time pdf's are well defined, but their mean transit time and higher-order moments become infinite. Several concrete geophysical examples are considered to illustrate under what conditions characteristics of tracer-age and transit-time pdf's can be inferred from observations in the atmosphere or the ocean. C1 Univ Victoria, Atmospher Environm Serv, Canadian Ctr Climate Modelling & Anal, Victoria, BC V8W 2Y2, Canada. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, New York, NY USA. RP Holzer, M (reprint author), Univ Victoria, Atmospher Environm Serv, Canadian Ctr Climate Modelling & Anal, Victoria, BC V8W 2Y2, Canada. NR 26 TC 115 Z9 115 U1 0 U2 6 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD NOV 1 PY 2000 VL 57 IS 21 BP 3539 EP 3558 DI 10.1175/1520-0469(2000)057<3539:TTATAD>2.0.CO;2 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 373PQ UT WOS:000165298200005 ER PT J AU Kortyna, A Darrach, MR Howe, PT Chutjian, A AF Kortyna, A Darrach, MR Howe, PT Chutjian, A TI High-resolution study of xenon autoionization using direct vacuum-ultraviolet laser excitation SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article ID IONIZING RYDBERG SERIES; QUANTUM-DEFECT THEORY; SPECTRAL-LINE SHAPES; PULSED FREE JETS; ALTERNATIVE PARAMETERS; CHANNEL INTERACTIONS; CROSS-SECTIONS; SPECTROSCOPY; GENERATION; RADIATION AB A new, direct vacuum-ultraviolet laser-excitation method is used to study the single-photon autoionization of xenon atoms in the 5p(6) --> 5p(5) ns'[1/2](1)(0) (14 less than or equal to n less than or equal to 52) and 5p(6) --> 5p(5) nd'[3/2](1)(0) (16 less than or equal to n less than or equal to 78) autoionizing Rydberg series. Fano profile parameters for both series are reported over the entire range of observed states. From analysis of the nd' series an ionization potential T-d = 108 370.82 +/- 0.05 cm(-1) is obtained. This agrees well with a previously reported limit of 108 370.8 +/- 0.2 cm(-1). (C) 2000 Optical Society of America [S0740-3224(00)00111-9]. C1 Colby Coll, Dept Phys & Astron, Waterville, ME 04901 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Colby Coll, Dept Phys & Astron, Waterville, ME 04901 USA. NR 43 TC 12 Z9 12 U1 0 U2 1 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 NOV PY 2000 VL 17 IS 11 BP 1934 EP 1942 DI 10.1364/JOSAB.17.001934 PG 9 WC Optics SC Optics GA 372KZ UT WOS:000165234000017 ER PT J AU Hash, DB Mihopoulos, T Govindan, TR Meyyappan, M AF Hash, DB Mihopoulos, T Govindan, TR Meyyappan, M TI Characterization of showerhead performance at low pressure SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article ID REACTOR; SILICON; SIMULATION; DEPOSITION AB The performance of showerheads used in semiconductor processing applications has been examined over a wide range of Knudsen number and Reynolds number. Both computational fluid dynamics and direct simulation Monte Carlo techniques have been used to characterize the showerhead flow with the intent of developing correlations between the upstream velocity and the pressure drop across the showerhead. Empirical correlations developed to account for entrance effects and rarefaction are also examined. Recommendations are made concerning boundary conditions and, when appropriate, correlations for given pressures and flow rates. (C) 2000 American Vacuum Society. [S0734-211X(00)14306-9]. C1 NASA, Ames Res Ctr, Eloret Corp, Moffett Field, CA 94035 USA. Motorola Inc, Austin, TX 78721 USA. RP Hash, DB (reprint author), NASA, Ames Res Ctr, Eloret Corp, Moffett Field, CA 94035 USA. NR 14 TC 3 Z9 5 U1 1 U2 5 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD NOV-DEC PY 2000 VL 18 IS 6 BP 2808 EP 2813 DI 10.1116/1.1322048 PG 6 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA 384HB UT WOS:000165935800038 ER PT J AU DellaCorte, C AF DellaCorte, C TI Volunteers the world over come to meet SO LUBRICATION ENGINEERING LA English DT Editorial Material C1 NASA, Glenn Res Ctr, Washington, DC 20546 USA. RP DellaCorte, C (reprint author), NASA, Glenn Res Ctr, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 840 BUSSE HIGHWAY, PARK RIDGE, IL 60068 USA SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD NOV PY 2000 VL 56 IS 11 BP 3 EP 3 PG 1 WC Engineering, Mechanical SC Engineering GA 373BA UT WOS:000165267500001 ER PT J AU Tumer, IY Wood, KL Busch-Vishniac, IJ AF Tumer, IY Wood, KL Busch-Vishniac, IJ TI Monitoring of signals from manufacturing processes using the Karhunen-Loeve transform SO MECHANICAL SYSTEMS AND SIGNAL PROCESSING LA English DT Article ID WIGNER-VILLE DISTRIBUTION; PATTERN-RECOGNITION; DECOMPOSITION; DIAGNOSIS AB Monitoring the condition of signals during manufacturing can provide valuable information about the status of the parts being produced, as well as that of the components of the manufacturing machine. To this end, we introduce a monitoring technique based on the Karhunen-Loeve transform, which decomposes measured manufacturing signals into decorrelated components in the form of fundamental eigenfunctions. The isolated eigenfunctions are monitored by means of the corresponding coefficient vectors, which indicate stationary and non-stationary changes in the deterministic and stochastic fundamental patterns. In this paper, the mathematical foundations of the technique are explored to form a good understanding of the mechanics of the transformation. This understanding is achieved with simple illustrative examples in the discrete and continuous domains, followed by an example of multicomponent signal decomposition by means of numerical simulations. The monitoring potential of the technique is illustrated with an example from a milling process, where the main modes are extracted by means of the eigenvectors and coefficient vectors. (C) 2000 Academic Press. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Texas, Austin, TX 78712 USA. Johns Hopkins Univ, Whiting Sch Engn, Baltimore, MD 21218 USA. RP Tumer, IY (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 43 TC 11 Z9 11 U1 0 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0888-3270 J9 MECH SYST SIGNAL PR JI Mech. Syst. Signal Proc. PD NOV PY 2000 VL 14 IS 6 BP 1011 EP 1026 DI 10.1006/mssp.1999.1278 PG 16 WC Engineering, Mechanical SC Engineering GA 384JL UT WOS:000165939000011 ER PT J AU Benedix, GK McCoy, TJ Keil, K Love, SG AF Benedix, GK McCoy, TJ Keil, K Love, SG TI A petrologic study of the IAB iron meteorites: Constraints on the formation of the IAB-Winonaite parent body SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID SILICATE-BEARING INCLUSIONS; ORDINARY CHONDRITES; ASTEROIDS; ORIGIN; IIICD; MINERALOGY; DIFFERENTIATION; CLASSIFICATION; FRAGMENTATION; METAMORPHISM AB We studied 26 IAB iron meteorites containing silicate-bearing inclusions to better constrain the many diverse hypotheses for the formation of this complex group. These meteorites contain inclusions that fall broadly into five types: (1) sulfide-rich, composed primarily of troilite and containing abundant embedded silicates; (2) nonchondritic, silicate-rich, comprised of basaltic, troctolitic, and peridotitic mineralogies; (3) angular, chondritic silicate-rich, the most common type, with approximately chondritic mineralogy and most closely resembling the winonaites in composition and texture; (4) rounded, often graphite-rich assemblages that sometimes contain silicates; and (5) phosphate-bearing inclusions with phosphates generally found in contact with the metallic host. Similarities in mineralogy and mineral and O-isotopic compositions suggest that IAB iron and winonaite meteorites are from the same parent body. We propose a hypothesis for the origin of IAB iron meteorites that combines some aspects of previous formation models for these meteorites. We suggest that the precursor parent body was chondritic, although unlike any known chondrite group. Metamorphism, partial melting,and incomplete differentiation (i.e., incomplete separation of melt from residue) produced metallic, sulfide-rich and silicate partial melts (portions of which may have crystallized prior to the mixing event), as well as metamorphosed chondritic materials and residues. Catastrophic impact breakup and reassembly of the debris while near the peak temperature mixed materials from various depths into the re-accreted parent body. Thus, molten metal from depth was mixed with near-surface silicate rock, resulting in the formation of silicate-rich IAB iron and winonaite meteorites. Results of smoothed particle hydrodynamic model calculations support the feasibility of such a mixing mechanism. Not all of the metal melt bodies were mixed with silicate materials during this impact and reaccretion event, and these are now represented by silicate-free IAB iron meteorites. Ages of silicate inclusions and winonaites of 4.40-4.54 Ga indicate this entire process occurred early in solar system history. C1 Arizona State Univ, Dept Geol, Tempe, AZ 85287 USA. Smithsonian Inst, Natl Museum Nat Hist, Dept Mineral Sci, Washington, DC 20560 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Hawaii Ctr Volcanol, Honolulu, HI USA. RP Benedix, GK (reprint author), Virginia Tech, Dept Geol Sci, Blacksburg, VA 24061 USA. OI Benedix, Gretchen/0000-0003-0990-8878 NR 66 TC 96 Z9 99 U1 0 U2 4 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD NOV PY 2000 VL 35 IS 6 BP 1127 EP 1141 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 385LF UT WOS:000166005400001 ER PT J AU Ferko, TE Schultz, L Franke, L Bogard, DD Garrison, DH Hutchison, R Lipschutz, ME AF Ferko, TE Schultz, L Franke, L Bogard, DD Garrison, DH Hutchison, R Lipschutz, ME TI Exposure history of the Mocs (L6) chondrite: A study of strewn field samples SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID ACCELERATOR-MASS-SPECTROMETRY; COSMOGENIC NUCLIDES; PRODUCTION-RATES; STONE METEORITES; JILIN CHONDRITE; NOBLE-GASES; AGES; NE-21; METEOROIDS; AL-26 AB We measured cosmogenic radionuclides ((10)Be, (26)Al, and (36)Cl) and noble gases (He, Ne, and Ar) in 10 specimens of the Mocs L6 chondrite to determine the exposure history and preatmospheric relationship among fragments from known locations in the strewn field. Cosmogenic noble gas contents alone are consistent with a simple irradiation exposure of 15.2 Ma. However, Mocs has very low (22)Ne/(21)Ne ratios indicative of deep burial in a large meteoroid, but radionuclide levels at saturation values typical for much smaller meteoroids: this paradox suggests a possible complex exposure. For the latter case, we propose a two-stage exposure history in which Mocs initially was deeply buried in a large object for 110 Ma, followed by exposure in a 65 cm object for 10.5 Ma. Relative shielding was inferred from the measured 22Ne/21Ne ratios assuming constant (22)Ne/(21)Ne production for all samples during the first stage. These shielding levels, which are supported by estimates based on (36)Cl production by neutron capture, indicate a possible relationship between depth of samples in the Mocs meteoroid and fall location in the strewn field. C1 Purdue Univ, Dept Chem, W Lafayette, IN 47907 USA. Max Planck Inst Chem, D-55020 Mainz, Germany. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Nat Hist Museum, Dept Mineral, London SW7 5BD, England. Lockheed Martin, Houston, TX 77058 USA. RP Lipschutz, ME (reprint author), Purdue Univ, Dept Chem, W Lafayette, IN 47907 USA. EM rnaapuml@purdue.edu NR 49 TC 10 Z9 10 U1 0 U2 1 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 NOV PY 2000 VL 35 IS 6 BP 1215 EP 1227 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 385LF UT WOS:000166005400009 ER PT J AU Krot, AN Meibom, A Petaev, MI Keil, K Zolensky, ME Saito, A Mukai, M Ohsumi, K AF Krot, AN Meibom, A Petaev, MI Keil, K Zolensky, ME Saito, A Mukai, M Ohsumi, K TI Ferrous silicate spherules with euhedral iron-nickel metal grains from CH carbonaceous chondrites: Evidence for supercooling and condensation under oxidizing conditions SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID PORPHYRITIC PYROXENE CHONDRULES; FEO-RICH; MODEL; PETROLOGY; ALH85085; CRYSTALLIZATION; SYSTEMS; POOR; CR AB The CH carbonaceous chondrites contain a population of ferrous (Fe/(Fe + Mg) approximate to 0.1-0.4) silicate spherules (chondrules), about 15-30 mum in apparent diameter, composed of cryptocrystalline olivine-pyroxene normative material, +/-SiO2-rich glass, and rounded-to-euhedral Fe,Ni metal grains. The silicate portions of the spherules are highly depleted in refractory lithophile elements (CaO, Al2O3, and TiO2 <0.04 wt%) and enriched in FeO, MnO, Cr2O3, and Na2O relative to the dominant, volatile-poor, magnesian chondrules from CH chondrites. The Fe/(Fe + Mg) ratio in the silicate portions of the spherules is positively correlated with Fe concentration in metal grains, which suggests that this correlation is not due to oxidation, reduction, or both of iron (FeOsil Fe-met) during melting of metal-silicate solid precursors. Rather, we suggest that this is a condensation signature of the precursors formed under oxidizing conditions. Each metal grain is compositionally uniform, but there are significant intergrain compositional variations: about 8-18 wt% Ni, <0.09 wt% Cr, and a sub-solar Co/Ni ratio. The precursor materials of these spherules were thus characterized by extreme elemental fractionations, which have not been observed in chondritic materials before. Particularly striking is the fractionation of Ni and Co in the rounded-to-euhedral metal grains, which has resulted in a Co/Ni ratio significantly below solar. The liquidus temperatures of the euhedral Fe,Ni metal grains are lower than those of the coexisting ferrous silicates, and we infer that the former crystallized in supercooled silicate melts. The metal grains are compositionally metastable; they are not decomposed into taenite and kamacite, which suggests fast postcrystallization cooling at temperatures below 970 K and lack of subsequent prolonged thermal metamorphism at temperatures above 400-500 K. C1 Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Inst Mat Struct Sci, Tsukuba, Ibaraki 305, Japan. RP Krot, AN (reprint author), Univ Hawaii Manoa, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. NR 21 TC 19 Z9 19 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD NOV PY 2000 VL 35 IS 6 BP 1249 EP 1258 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 385LF UT WOS:000166005400012 ER PT J AU Campbell, MD Brown, PG LeBlanc, AG Hawkes, RL Jones, J Worden, SP Correll, RR AF Campbell, MD Brown, PG LeBlanc, AG Hawkes, RL Jones, J Worden, SP Correll, RR TI Image-intensified video results from the 1998 Leonid shower: I. Atmospheric trajectories and physical structure SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID METEORS; ABLATION; ORBITS AB Two-station electro-optical observations of the 1998 Leonid shower are presented. Precise heights and light curves were obtained for 79 Leonid meteors that ranged in brightness (at maximum luminosity) from +0.3 to +6.1 astronomical magnitude. The mean photometric mass of the data sample was 1.4 x 10(-6) kg. The dependence of astronomical magnitude at peak luminosity on photometric mass and zenith angle was consistent with earlier studies of faint sporadic meteors. For example, a Leonid meteoroid with a photometric mass of similar to1.0 x 10(-7) kg corresponds to a peak meteor luminosity of about +4.5 astronomical magnitudes. The mean beginning height of the Leonid meteors in this sample was 112.6 km and the mean ending height was 95.3 km. The highest beginning height observed was 144.3 km. There is relatively little dependence of either the first or last heights on mass, which is indicative of meteoroids that have clustered into constituent grains prior to the onset of intensive grain ablation. The height distribution, combined with numerical modelling of the ablation of the meteoroids, suggests that silicate-like materials are not the principal component of Leonid meteoroids and hints at the presence of a more volatile component. Light curves of many Leonid meteors were examined for evidence of the physical structure of the associated meteoroids: similar to the 1997 Leonid meteors, the narrow, nearly symmetric curves imply that the meteoroids are not solid objects. The light curves are consistent with a dustball structure. C1 Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada. Mt Allison Univ, Dept Phys, Sackville, NB E4L 1E6, Canada. USAF Headquarters, Washington, DC 20330 USA. NASA Headquarters, Washington, DC 20546 USA. USAF Headquarters, Space Command, Washington, DC 20546 USA. RP Campbell, MD (reprint author), Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada. NR 40 TC 39 Z9 39 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD NOV PY 2000 VL 35 IS 6 BP 1259 EP 1267 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 385LF UT WOS:000166005400013 ER PT J AU Morbidelli, A Chambers, J Lunine, JI Petit, JM Robert, F Valsecchi, GB Cyr, KE AF Morbidelli, A Chambers, J Lunine, JI Petit, JM Robert, F Valsecchi, GB Cyr, KE TI Source regions and timescales for the delivery of water to the Earth SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID SHORT-PERIOD COMETS; ASTEROID BELT; SOLAR NEBULA; CARBONACEOUS CHONDRITES; ISOTOPIC COMPOSITIONS; DEUTERIUM ENRICHMENT; SUBMARINE BASALTS; PROTOSOLAR CLOUD; OCEANIC BASALTS; GIANT PLANETS AB In the primordial solar system, the most plausible sources of the water accreted by the Earth were in the outer asteroid belt, in the giant planet regions, and in the Kuiper Belt. We investigate the implications on the origin of Earth's water of dynamical models of primordial evolution of solar system bodies and check them with respect to chemical constraints. We find that it is plausible that the Earth accreted water all along its formation, from the early phases when the solar nebula was still present to the late stages of gas-free sweepup of scattered planetesimals. Asteroids and the comets from the Jupiter-Saturn region were the first water deliverers, when the Earth was less than half its present mass. The bulk of the water presently on Earth was carried by a few planetary embryos, originally formed in the outer asteroid belt and accreted by the Earth at the final stage of its formation. Finally, a late veneer, accounting for at most 10% of the present water mass, occurred due to comets from the Uranus-Neptune region and from the Kuiper Belt. The net result of accretion from these several reservoirs is that the water on Earth had essentially the D/H ratio typical of the water condensed in the outer asteroid belt. This is in agreement with the observation that the D/H ratio in the oceans is very close to the mean value of the D/H ratio of the water inclusions in carbonaceous chondrites. C1 Observ Cote Azur, F-06003 Nice, France. Armagh Observ, Armagh BT61 9DG, North Ireland. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Museum Hist Nat, Paris, France. Ist Astrofis Spaziale, Rome, Italy. NASA, Lyndon B Johnson Space Ctr, Planetary Sci Branch, Houston, TX 77058 USA. RP Morbidelli, A (reprint author), Observ Cote Azur, F-06003 Nice, France. OI Valsecchi, Giovanni/0000-0002-2915-1465 NR 74 TC 394 Z9 399 U1 7 U2 85 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD NOV PY 2000 VL 35 IS 6 BP 1309 EP 1320 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 385LF UT WOS:000166005400017 ER PT J AU Buchanan, PC Lindstrom, DJ Mittlefehldt, DW Koeberl, C Reimold, WU AF Buchanan, PC Lindstrom, DJ Mittlefehldt, DW Koeberl, C Reimold, WU TI The south African polymict eucrite Macibini SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID PARENT BODY; HOWARDITE; ABUNDANCES; METEORITES; MINERALOGY; PETROLOGY; PYROXENE; SAMPLES; BASALT AB The polymict eucrite Macibini is a fragmental breccia, predominantly composed of eucritic materials with minor proportions (maximum 2 vol%) of diogenitic material. Hence, it is intermediate between the Yamato-74159-type polymict eucrites, which contain negligible amounts of magnesian orthopyroxene, and the howardites. The present study provides mineralogical and bulk compositional data for the meteorite breccia and for six clasts. These clasts include both volcanic and igneous rocks and a variety of impact-generated rocks. A broad range of degrees of postcrystallization metamorphism affected these materials before the final aggregation of the breccia. Clast A is a fragment of unequilibrated eucrite with subophitic texture. The edges of the zoned pyroxenes in this clast are composed of a host of Fe-rich augite containing vermicules (blebs) and lamellae composed of a mixture of Fe-rich olivine and silica. Similar features occur as fragments in lunar breccias and are attributed by some workers to the breakdown of pyroxferroite, an Fe-rich pyroxenoid. However, textures and compositions of these augite-olivine-silica intergrowths in clast A suggest that, in this case, they are the result of decomposition in a series of steps of Fe-rich subcalcic augite. Among the fragments of impact-generated material in Macibini is clast 2, an earlier-formed elastic breccia that was lithified before being broken apart and included in the meteorite breccia. Clast 3 is an impact-melt breccia that is composed of rock and mineral fragments in a devitrified groundmass. Clast C is also an impact-melt breccia that has a coarser-grained, hornfelsic groundmass that resulted from extensive metamorphism after formation. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Univ Witwatersrand, Dept Geol, ZA-2050 Johannesburg, South Africa. Lockheed Martin ESS, Houston, TX 77058 USA. Univ Vienna, Inst Geochem, A-1090 Vienna, Austria. RP Buchanan, PC (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SN2, Houston, TX 77058 USA. NR 46 TC 22 Z9 22 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD NOV PY 2000 VL 35 IS 6 BP 1321 EP 1331 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 385LF UT WOS:000166005400018 ER PT J AU Krot, AN Brearley, AJ Petaev, MI Kallemeyn, GW Sears, DWG Benoit, PH Hutcheon, ID Zolensky, ME Keil, K AF Krot, AN Brearley, AJ Petaev, MI Kallemeyn, GW Sears, DWG Benoit, PH Hutcheon, ID Zolensky, ME Keil, K TI Evidence for low-temperature growth of fayalite and hedenbergite in MacAlpine Hills 88107, an ungrouped carbonaceous chondrite related to the CM-CO clan SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID EARLY SOLAR-SYSTEM; COMPOSITIONAL CLASSIFICATION; AQUEOUS ALTERATION; ASTEROIDAL ALTERATION; OXYGEN-ISOTOPE; CV3 CHONDRITES; BASALT GLASS; NEBULA; MOKOIA; CONDENSATION AB The carbonaceous chondrite MacAlpine Hills (MAC) 88107 has bulk composition and mineralogy that are intermediate between those of CO and CM chondrites. This meteorite experienced minor alteration and a low degree of thermal metamorphism (petrologic type 3.1) and escaped post-accretional brecciation. The alteration resulted in the formation of fayalite (Fa(90-100)), Al-free hedenbergite (similar to Fs(50)Wo(50)), phyllosilicates (saponite-serpentine intergrowths), magnetite, and Ni-bearing sulfides (pyrrhotite and pentlandite). Fayalite and hedenbergite typically occur as veins, which start at the opaque nodules in the chondrule peripheries, crosscut fine-grained rims and either terminate at the boundaries with the neighboring fine-grained rims or continue as layers between these rims. These observations suggest that fayalite and hedenbergite crystallized after accretion and compaction of the fine-grained rims. Fayalite also overgrows isolated forsteritic (Fa(1-5)) and fayalitic (Fa(20-40)) olivine grains without any evidence for Fe-Mg interdiffusion; it also replaces massive magnetite-sulfide grains. The initial Mn-53/Mn-55 ratio of (1.58 +/- 0.26) x 10(-6) in the MAC 88107 fayalite corresponds to an age difference between the formation of fayalite and refractory inclusions in Allende of either similar to9 or 18 Ma, depending upon the value of the solar system initial abundance of Mn-53 used in age calculations. Formation of secondary fayalite and hedenbergite requires mobilization and transport of Ca, Si, and Fe either through a high-temperature gaseous phase (Hua and Buseck, 1995) or low-temperature aqueous solution (Krot et al., 1998a,b). The high-temperature nebular model for the origin of fayalite (Hua and Buseck, 1995) fails to explain (a) formation of fayalite-hedenbergite assemblages after accretion of fine-grained rims that lack any evidence for high-temperature processing; (b) extreme fractionation of refractory lithophile elements of similar volatility, Ca and Al, in hedenbergite; and (c) absence of Fe-Mg interdiffusion along fayalite-forsterite boundaries. We conclude that fayalite and hedenbergite in MAC 88107 formed during late-stage, low-temperature (approximately 150-200 degreesC) aqueous alteration. The data for MAC 88107 extend the evidence for an early onset of aqueous activity on chondrite parent bodies and reinforce the conclusion that liquid water played an important role in the chemical and mineralogical evolution of the first chondritic planetesimals. C1 Univ Hawaii, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Univ New Mexico, Albuquerque, NM 87131 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Tokyo Metropolitan Univ, Dept Math, Grad Sch Sci, Tokyo 1920397, Japan. Univ Arkansas, Dept Chem & Biochem, Fayetteville, AR 72701 USA. Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94551 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Krot, AN (reprint author), Univ Hawaii, Sch Ocean & Earth Sci & Technol, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. NR 59 TC 27 Z9 27 U1 1 U2 5 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD NOV PY 2000 VL 35 IS 6 BP 1365 EP 1386 PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 385LF UT WOS:000166005400021 ER PT J AU Hof, M Bremerich, M Gobel, H Hams, T Menn, W Simon, M Barbier, LM Christian, ER Geier, S Gupta, SK Krizmanic, JF Mitchell, JW Ormes, JF Streitmatter, RE Davis, AJ de Nolfo, GA Mewaldt, RA Schindler, SM AF Hof, M Bremerich, M Gobel, H Hams, T Menn, W Simon, M Barbier, LM Christian, ER Geier, S Gupta, SK Krizmanic, JF Mitchell, JW Ormes, JF Streitmatter, RE Davis, AJ de Nolfo, GA Mewaldt, RA Schindler, SM TI ISOMAX: a balloon-borne instrument to measure cosmic ray isotopes SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 1st International Symposium on Applications of Particle Detectors in Medicine, Biology and Astrophysics (SAMBA 99) CY OCT 06-08, 1999 CL SIEGEN, GERMANY SP Univ Siegen, Res Inst Humanities & Social Sci DE cosmic rays; balloons; isotopes ID SPECTROMETER; PERFORMANCE AB The Isotope Magnet Experiment (ISOMAX) is a new balloon-borne instrument developed to measure the isotopic composition of the light elements in the cosmic radiation, in particular to obtain the ratio of the radioactive Be-10 to stable Be-9. ISOMAX was first flown in August 4-5, 1998, from Lynn Lake, Manitoba, Canada ISOMAX has a geometry factor of 450 cm(2) sr and was configured for this flight with a large, Helmholtz-like, superconducting magnet in combination with a drift-chamber tracking system, a state-of-the-art time-of-flight system and two aerogel Cherenkov detectors to measure light isotopes with a mass resolution of better than 0.25 amu. In the 1998 flight the obtained maximum detectable rigidity of the magnetic spectrometer was 970 GV/c for helium at 60% of the full magnetic field. ISOMAX took data for more than 16 h at float altitudes above 36 km. We here present the performance of the individual detectors and initial isotopic results of the instrument. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Univ Gesamthsch Siegen, Fachbereich Phys, D-57068 Siegen, Germany. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. CALTECH, Space Radiat Lab, Pasadena, CA 91125 USA. RP Hof, M (reprint author), Univ Gesamthsch Siegen, Fachbereich Phys, D-57068 Siegen, Germany. RI de Nolfo, Georgia/E-1500-2012; Christian, Eric/D-4974-2012 OI Christian, Eric/0000-0003-2134-3937 NR 13 TC 2 Z9 2 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD NOV 1 PY 2000 VL 454 IS 1 BP 180 EP 185 DI 10.1016/S0168-9002(00)00823-8 PG 6 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 377KZ UT WOS:000165513900020 ER PT J AU Biswas, R Hendrickson, B Karypis, G AF Biswas, R Hendrickson, B Karypis, G TI Graph partitioning and parallel computing SO PARALLEL COMPUTING LA English DT Editorial Material C1 NASA, Ames Res Ctr, MRJ Technol Solut, Moffett Field, CA 94035 USA. Sandia Natl Labs, Parallel Comp Sci Dept, Albuquerque, NM 87185 USA. Univ Minnesota, Dept Comp Sci, Minneapolis, MN 55455 USA. RP Biswas, R (reprint author), NASA, Ames Res Ctr, MRJ Technol Solut, MS T27A-1, Moffett Field, CA 94035 USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-8191 J9 PARALLEL COMPUT JI Parallel Comput. PD NOV PY 2000 VL 26 IS 12 BP 1515 EP 1517 DI 10.1016/S0167-8191(00)00042-9 PG 3 WC Computer Science, Theory & Methods SC Computer Science GA 362LL UT WOS:000089779400001 ER PT J AU Oliker, L Biswas, R Gabow, HN AF Oliker, L Biswas, R Gabow, HN TI Parallel tetrahedral mesh adaptation with dynamic load balancing SO PARALLEL COMPUTING LA English DT Article DE unstructured-meshes; graph repartitioning; data remapping; redistribution cost metrics; portability analysis ID ADAPTIVE UNSTRUCTURED MESHES; CONSERVATION-LAWS; ALGORITHMS; GRIDS; COMPUTATIONS; MODEL AB The ability to dynamically adapt an unstructured-grid is a powerful tool for efficiently solving computational problems with evolving physical features. In this paper, we report on our experience parallelizing an edge-based adaptation scheme, called 3D_TAG, using message passing. Results show excellent speedup when a realistic helicopter rotor mesh is randomly refined. However, performance deteriorates when the mesh is refined using a solution-based error indicator since mesh adaptation for practical problems occurs in a localized region, creating a severe load imbalance. To address this problem, we have developed PLUM, a global dynamic load balancing framework for adaptive numerical computations. Even though PLUM primarily balances processor workloads for the solution phase, it reduces the load imbalance problem within mesh adaptation by repartitioning the mesh after targeting edges for refinement but before the actual subdivision. This dramatically improves the performance of parallel 3D_TAG since refinement occurs in a more load balanced fashion. We also present optimal and heuristic algorithms that, when applied to the default mapping of a parallel repartitioner, significantly reduce the data redistribution overhead. Finally, portability is examined by comparing performance on three state-of-the-art parallel machines, (C) 2000 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, MRJ Technol Solut, Moffett Field, CA 94035 USA. Univ Colorado, Dept Comp Sci, Boulder, CO 80309 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, NERSC, Berkeley, CA 94720 USA. RP Biswas, R (reprint author), NASA, Ames Res Ctr, MRJ Technol Solut, MS T27 A-1, Moffett Field, CA 94035 USA. EM loliker@lbl.gov; rbiswas@nas.nasa.gov; hal@piper.cs.colorado.edu NR 31 TC 24 Z9 24 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-8191 J9 PARALLEL COMPUT JI Parallel Comput. PD NOV PY 2000 VL 26 IS 12 BP 1583 EP 1608 DI 10.1016/S0167-8191(00)00047-8 PG 26 WC Computer Science, Theory & Methods SC Computer Science GA 362LL UT WOS:000089779400005 ER PT J AU Davis, B Macauley, M AF Davis, B Macauley, M TI NASA's Affiliated Research Center Program: Bridging basic research and quality of life SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Editorial Material C1 NASA, Commercial Remote Sensing Program Off, Stennis Space Ctr, MS 39597 USA. RP Davis, B (reprint author), NASA, Commercial Remote Sensing Program Off, Bldg 1100, Stennis Space Ctr, MS 39597 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 USA SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD NOV PY 2000 VL 66 IS 11 BP 1289 EP + PG 4 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 368LW UT WOS:000090119300002 ER PT J AU Lakhina, GS Tsurutani, BT Arballo, JK Galvan, C AF Lakhina, GS Tsurutani, BT Arballo, JK Galvan, C TI Sun-Earth connection: Boundary layer waves and auroras SO PRAMANA-JOURNAL OF PHYSICS LA English DT Article; Proceedings Paper CT 14th Natioal Symposium on Plasma Science and technology (Plasma-99) CY DEC 21-24, 1999 CL GURU NANAK DEV UNIV, AMRITSAR, INDIA SP Plasma Sci Soc India, CSIR, DST, DAE, IIGM, MIT, AICTE, SINP HO GURU NANAK DEV UNIV DE wave-particle interactions; boundary layer waves; aurora ID BAND ELECTROSTATIC NOISE; PLASMA SHEET BOUNDARY; ELECTRIC-FIELD STRUCTURES; HYBRID DRIFT INSTABILITY; ION-BEAM INSTABILITIES; DAYSIDE MAGNETOPAUSE; MAGNETOSPHERIC BOUNDARY; 2-STREAM INSTABILITIES; PARTICLE INTERACTIONS; GENERATION MECHANISM AB Boundary layers are the sites where energy and momentum are exchanged between two distinct plasmas. Boundary layers occurring in space plasmas can support a wide spectrum of plasma waves spanning a frequency range of a few mHz to 100 kHz and beyond. The main characteristics of the broadband plasma waves (with frequencies > 1 Hz) observed in the magnetopause, polar cap, and plasma sheet boundary layers are described. The rapid pitch angle scattering of energetic particles via cyclotron resonant interactions with the waves can provide sufficient precipitated energy flux to the ionosphere to create the diffused auroral oval. The broadband plasma waves may also play an important role in the processes of local heating/acceleration of the boundary layer plasma. C1 Indian Inst Geomagnetism, Bombay 400005, Maharashtra, India. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Lakhina, GS (reprint author), Indian Inst Geomagnetism, Bombay 400005, Maharashtra, India. RI Lakhina, Gurbax /C-9295-2012; OI Lakhina, Gurbax /0000-0002-8956-486X NR 76 TC 2 Z9 2 U1 1 U2 2 PU INDIAN ACADEMY SCIENCES PI BANGALORE PA P B 8005 C V RAMAN AVENUE, BANGALORE 560 080, INDIA SN 0304-4289 J9 PRAMANA-J PHYS JI Pramana-J. Phys. PD NOV-DEC PY 2000 VL 55 IS 5-6 SI SI BP 665 EP 683 DI 10.1007/s12043-000-0032-2 PG 19 WC Physics, Multidisciplinary SC Physics GA 389FW UT WOS:000166228800004 ER PT J AU Gatski, TB Jongen, T AF Gatski, TB Jongen, T TI Nonlinear eddy viscosity and algebraic stress models for solving complex turbulent flows SO PROGRESS IN AEROSPACE SCIENCES LA English DT Review ID LOW-REYNOLDS-NUMBER; HOMOGENEOUS TURBULENCE; EQUILIBRIUM STATES; SIMULATION DATA; CHANNEL FLOW; NEAR-WALL; CLOSURE; EXPLICIT; PREDICTION; EQUATION AB Nonlinear eddy viscosity and algebraic stress models are currently providing an invaluable link between the more common linear eddy viscosity turbulence models and the full differential Reynolds stress forms. With the increased popularity has come an abundance of different formulations. The purpose of this review is to provide a cohesive framework for the variety of models proposed and to highlight the various similarities and differences among the models. Their link with differential Reynolds stress models and their improved predictive capability over linear eddy-viscosity models is also highlighted, (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Unilever Res Labs Vlaardingen, NL-3130 AC Vlaardingen, Netherlands. RP Gatski, TB (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 62 TC 65 Z9 69 U1 0 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0376-0421 J9 PROG AEROSP SCI JI Prog. Aeosp. Sci. PD NOV PY 2000 VL 36 IS 8 BP 655 EP 682 DI 10.1016/S0376-0421(00)00012-9 PG 28 WC Engineering, Aerospace SC Engineering GA 384NW UT WOS:000165952600003 ER PT J AU Appelbaum, J Croitoru, N Klibanov, L Scheinman, D AF Appelbaum, J Croitoru, N Klibanov, L Scheinman, D TI The effect of electron damage on silicon solar cells coated with diamond-like carbon films SO PROGRESS IN PHOTOVOLTAICS LA English DT Article AB The unique properties of the diamond-like carbon (a:DLC), such as high mechanical hardness and abrasive resistance, optical transparency in the visible and IR spectral regions and high thermal conductivity, provide this material with advantages over other types of protecting materials for solar cells. Furthermore, the a:DLC films are inert to corrosive gases and other corrosive agents. Resistance to radiation damage of the a:DLC films deposited on solar cells is very important for space application. In the study we investigate the effect of electron damage on silicon solar cells coated with a:DLC films. We measure the IV characteristic and the spectral response and calculate the values of the screen parameters of the double exponential solar cell model (usually not investigated) as a function of electron fluence irradiation. In addition we obtain also the usual external parameters I-SC, V-OC, I-m, V-m, FF, and efficiency) of the solar cells. we investigate solar cells with and without anti-reflecting coating with a:DLC films which were exposed to electron radiation. The main findings show that the solar cells with a:DLC films of thickness up to 500 nm degrade similarly to regular silicon cells exposed to electron irradiation. The degradation of the spectral response of the solar cell is mainly in the range of longer wavelengths and the irradiation affects the solar cell parameters (mainly the reverse saturation currents). Copyright (C) 2000 John Wiley & Sons, Ltd. C1 Tel Aviv Univ, Fac Engn, IL-69978 Tel Aviv, Israel. NASA, Glenn Res Ctr, Ohio Aerosp Inst, Cleveland, OH 44135 USA. RP Appelbaum, J (reprint author), Tel Aviv Univ, Fac Engn, IL-69978 Tel Aviv, Israel. NR 21 TC 0 Z9 0 U1 3 U2 5 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 1062-7995 J9 PROG PHOTOVOLTAICS JI Prog. Photovoltaics PD NOV-DEC PY 2000 VL 8 IS 6 BP 571 EP 578 DI 10.1002/1099-159X(200011/12)8:6<571::AID-PIP329>3.0.CO;2-7 PG 8 WC Energy & Fuels; Materials Science, Multidisciplinary; Physics, Applied SC Energy & Fuels; Materials Science; Physics GA 392XT UT WOS:000166438400002 ER PT J AU Leslie, FW Cha, SS Ramachandran, N AF Leslie, FW Cha, SS Ramachandran, N TI A simple approach for calibrating solid-state imaging systems SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB Imaging by solid-state array sensors has become an indispensable tool in various modern scientific and engineering applications. In such instrumentation, a linear response of the sensor output to the incident light intensity is often very much desirable. The system linearity can be affected by both the sensing element and electronics. The linearity also needs to be accurately determined in order to assess and correct measurement errors. Some imaging systems, especially those of upper grade with high resolution, allow precise control of exposure time. If so, it is easy to check the linearity in response to the incident energy with changes of exposure time under a constant intensity of illuminating light. For imaging systems without precise time control, especially those of intermediate- or lower-grade, it is highly desirable to have some means for assessing linearity and applying corrections to improve accuracy for photometric uses. Here, we present two simple approaches, one for quickly checking linearity and the other for correcting the response, for those imaging systems without exact exposure-time control. The former allows a quick assessment of the linearity while the latter permits an accurate calibration with minimal hardware preparation. In initial testing, the calibration method works well with an intermediate-grade sensor interfaced to a frame grabber. The nonlinearity of the imaging system tested can be reduced from about 5.1% to much less than 1% in standard deviation. (C) 2000 American Institute of Physics. [S0034-6748(00)00612-2]. C1 NASA, George C Marshall Space Flight Ctr, SD47, Huntsville, AL 35812 USA. Univ Illinois, Chicago, IL 60607 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. RP Leslie, FW (reprint author), NASA, George C Marshall Space Flight Ctr, SD47, Huntsville, AL 35812 USA. NR 8 TC 2 Z9 2 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD NOV PY 2000 VL 71 IS 11 BP 4149 EP 4154 DI 10.1063/1.1319983 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 369TY UT WOS:000165084100024 ER PT J AU Hansen, JE AF Hansen, JE TI The sun's role in long-term climate change SO SPACE SCIENCE REVIEWS LA English DT Review ID SOLAR-CYCLE VARIABILITY; ATMOSPHERIC METHANE; SULFATE AEROSOLS; IRRADIANCE; FORCINGS; CARBON; TRENDS; IMPACT; OZONE AB Evidence suggests that changes of solar irradiance in recent centuries have provided a significant climate forcing and that the sun has been one of the principal causes of long-term climate change. During the past two decades the solar forcing has been much smaller than the climate forcing caused by increasing greenhouse gases. But it is incorrect to assume that the sun necessarily will be an insignificant player in climate change of the 21st century. Indeed, I argue that moderate success in curtailing the growth of anthropogenic climate forcings could leave the sun playing a pivotal role in future climate change. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM jhansen@giss.nasa.gov NR 28 TC 12 Z9 12 U1 0 U2 5 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD NOV PY 2000 VL 94 IS 1-2 BP 349 EP 356 DI 10.1023/A:1026748129347 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 379FM UT WOS:000165631400031 ER PT J AU Asenov, A Kaya, S Davies, JH Saini, S AF Asenov, A Kaya, S Davies, JH Saini, S TI Oxide thickness variation induced threshold voltage fluctuations in decanano MOSFETs: a 3D density gradient simulation study SO SUPERLATTICES AND MICROSTRUCTURES LA English DT Article; Proceedings Paper CT 5th Silicon Nanoelectronics Workshop CY JUN 11-12, 2000 CL HONOLULU, HAWAII SP Inst Elect & Electr Engineers DE MOSFETs; scaling; interface; roughness; density gradient ID ATOMISTIC SIMULATION; SURFACE-ROUGHNESS; SI-SIO2 INTERFACE; INVERSION LAYER; GATE OXIDE; DOPANT; ELECTRON; MOBILITY AB We use the density gradient (DG) simulation approach to study, in 3D, the effect of local oxide thickness fluctuations on the threshold voltage of decanano MOSFETs in a statistical manner. A description of the reconstruction procedure for the random 2D surfaces representing the 'atomistic' Si-SiO2 interface variations is presented. The procedure is based on power spectrum synthesis in the Fourier domain acid can include either Gaussian or exponential spectra. The simulations show that threshold voltage variations induced by oxide thickness fluctuation become significant when the gate length of the devices become comparable to the correlation length of the fluctuations. The extent of quantum corrections in the simulations with respect to the classical case and the dependence of threshold variations on the oxide thickness are examined. (C) 2000 Academic Press. C1 Univ Glasgow, Dept Elect & Elect Engn, Device Modelling Grp, Glasgow G12 8LT, Lanark, Scotland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Asenov, A (reprint author), Univ Glasgow, Dept Elect & Elect Engn, Device Modelling Grp, Glasgow G12 8LT, Lanark, Scotland. NR 18 TC 12 Z9 12 U1 0 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0749-6036 J9 SUPERLATTICE MICROST JI Superlattices Microstruct. PD NOV-DEC PY 2000 VL 28 IS 5-6 BP 507 EP 515 DI 10.1006/spmi.2000.0955 PG 9 WC Physics, Condensed Matter SC Physics GA 384AT UT WOS:000165917400027 ER PT J AU Lee, KN AF Lee, KN TI Current status of environmental barrier coatings for Si-based ceramics SO SURFACE & COATINGS TECHNOLOGY LA English DT Article; Proceedings Paper CT 27th International Conference on Metallurgical Coatings and Thin Films CY APR 10-14, 2000 CL SAN DIEGO, CA SP Amer Vacuum Soc, Adv Surface Engn Div DE environmental barrier coatings; Si-based ceramics; mullite-based composite bond coat; BSAS ID MULLITE COATINGS; SILICON-CARBIDE; OXIDATION; TEMPERATURE AB Silicon-based ceramics are the leading candidates for high temperature structural components in next generation gas turbine engines. One key drawback of silicon-based ceramics for such an application is volatilization of the protective silica scale in water vapor and the resulting rapid ceramic recession. Therefore, the realization of Si-based ceramics components in advanced gas turbine engines depends on the development of protection schemes from water vapor attack. Currently, plasma-sprayed external environmental barrier coatings (EBCs) are the most promising approach. In the late 1980s and early 1990s a wide range of refractory oxide materials were tested as coatings on Si-based ceramics to provide protection from hot corrosion. After the discovery of silica volatilization in water vapor in the early 1990s, the focus of EBC development research has been shifted towards the protection from water vapor attack. Experience learned form the earlier coating developmental effort provided the foundation upon which more complex and advanced EBC coatings have been developed. This paper will discuss the brief history and the current status of EBC development for Si-based ceramics with the main focus on water vapor protection. (C) 2000 Elsevier Science B.V. All rights reserved. C1 Cleveland State Univ, Dept Chem Engn, Cleveland, OH 44115 USA. RP Lee, KN (reprint author), NASA, Glenn Res Ctr MS106 1, 21000 Brook Pk Rd, Cleveland, OH 44135 USA. EM kang.n.lee@grc.nasa.gov NR 18 TC 151 Z9 158 U1 7 U2 69 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0257-8972 J9 SURF COAT TECH JI Surf. Coat. Technol. PD NOV PY 2000 VL 133 BP 1 EP 7 DI 10.1016/S0257-8972(00)00889-6 PG 7 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA 383MX UT WOS:000165887500002 ER PT J AU Feiveson, AH Kulkarni, PM AF Feiveson, AH Kulkarni, PM TI Reliability of space-shuttle pressure vessels with random batch effects SO TECHNOMETRICS LA English DT Article DE accelerated testing; bootstrap; pivotal method; reliability; subsampling; Weibull ID MAXIMUM-LIKELIHOOD; STANDARD-DEVIATION; LINEAR-MODELS; WEIBULL; PARAMETER; BIAS AB In this article we revisit the problem of estimating the joint reliability against failure by stress rupture of a group of fiber-wrapped pressure vessels used on Space-Shuttle missions. The available test data were obtained from an experiment conducted at the U.S. Department of Energy Lawrence Livermore Laboratory (LLL) in which scaled-down vessels were subjected to life testing at four accelerated levels of pressure. We estimate the reliability assuming that both the Shuttle and LLL vessels were chosen at random in a two-stage process from an infinite population with spools of fiber as the primary sampling unit. Two main objectives of this work are (1) to obtain practical estimates of reliability taking into account random spool effects and (2) to obtain a realistic assessment of estimation accuracy under the random model. Here, reliability is calculated in terms of a "system" of 22 fiber-wrapped pressure vessels, taking into account typical pressures and exposure times experienced by Shuttle vessels. Comparisons are made with previous studies. The main conclusion of this study is that, although point estimates of reliability are still in the "comfort zone" it is advisable to plan for replacement of the pressure vessels well before the expected lifetime of 100 missions per Shuttle Orbiter. Under a random-spool model, there is simply not enough information in the LLL data to provide reasonable assurance that such replacement would not be necessary. C1 Lyndon B Johnson Space Ctr, Div Med Sci, Houston, TX 77058 USA. Univ S Alabama, Dept Math & Stat, Mobile, AL 36888 USA. RP Lyndon B Johnson Space Ctr, Div Med Sci, Houston, TX 77058 USA. EM alan.h.feiveson1@jsc.nasa.gov; kulkarni@mathstat.usouthal.edu NR 33 TC 10 Z9 10 U1 1 U2 1 PU AMER STATISTICAL ASSOC PI ALEXANDRIA PA 732 N WASHINGTON ST, ALEXANDRIA, VA 22314-1943 USA SN 0040-1706 EI 1537-2723 J9 TECHNOMETRICS JI Technometrics PD NOV PY 2000 VL 42 IS 4 BP 332 EP 344 DI 10.2307/1270943 PG 13 WC Statistics & Probability SC Mathematics GA 410KE UT WOS:000167438500002 ER PT J AU Hodis, HN Mack, WJ Lobo, RA Shoupe, D Sevanian, A Mahrer, PR Seizer, RH Liu, CR Liu, CH Azen, SP AF Hodis, HN Mack, WJ Lobo, RA Shoupe, D Sevanian, A Mahrer, PR Seizer, RH Liu, CR Liu, CH Azen, SP TI Estrogen in the Prevention of Atherosclerosis Trial SO CIRCULATION LA English DT Meeting Abstract C1 Univ So Calif, Los Angeles, CA 90089 USA. Columbia Univ Coll Phys & Surg, New York, NY 10032 USA. Kaiser Permanente Med Ctr, Los Angeles, CA 90034 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. NR 0 TC 10 Z9 10 U1 0 U2 0 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0009-7322 J9 CIRCULATION JI Circulation PD OCT 31 PY 2000 VL 102 IS 18 SU S MA 4021 BP 837 EP 837 PG 1 WC Cardiac & Cardiovascular Systems; Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA 367QE UT WOS:000090072304012 ER PT J AU Whittenberger, JD Grahle, P Behr, R Arzt, E Hebsur, MG AF Whittenberger, JD Grahle, P Behr, R Arzt, E Hebsur, MG TI Elevated temperature compressive strength properties of oxide dispersion strengthened NiAl after cryomilling and roasting in nitrogen SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article DE oxide dispersion strengthened NiAl; cryomilled NiAl; elevated temperature creep properties ID CREEP; INTERMETALLICS; MICROSTRUCTURE; ALN AB In an effort to superimpose two different elevated temperature strengthening mechanisms in NiAl, several lots of oxide dispersion strengthened (ODS) NiAl powder have been cryomilled in liquid nitrogen to introduce AIN particles at the grain boundaries. As an alternative to cryomilling, one lot of ODS NiAl was also roasted in nitrogen to produce AlN. Both techniques resulted in hot extruded AlN-strengthened ODS NiAl alloys which were stronger than the base ODS NiAl between 1200 and 1400 K. However neither the cryomilled nor the N-2-roasted ODS NiAl alloys were as strong as cryomilled binary NiAl containing like amounts of AIN. The reason(s) for the relative weakness of cryomilled ODS NiAl is not certain; however the lack of superior strength in N-2-roasted ODS NiAl is probably due to its relatively large AlN particles. (C) 2000 Elsevier Science S.A. All rights reserved. C1 NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. Max Planck Inst Met Res, Stuttgart, Germany. NASA, OAI, GRC Grp, Brookpark, OH 44142 USA. RP Whittenberger, JD (reprint author), NASA, Glenn Res Ctr Lewis Field, Cleveland, OH 44135 USA. EM john.d.whittenberger@grc.nasa.gov RI Arzt, Eduard/B-5282-2008 NR 21 TC 7 Z9 7 U1 2 U2 5 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD OCT 31 PY 2000 VL 291 IS 1-2 BP 173 EP 185 DI 10.1016/S0921-5093(00)00938-2 PG 13 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 352ZK UT WOS:000089249100022 ER PT J AU Elmustafa, AA Eastman, JA Rittner, MN Weertman, JR Stone, DS AF Elmustafa, AA Eastman, JA Rittner, MN Weertman, JR Stone, DS TI Indentation size effect: Large grained aluminum versus nanocrystalline aluminum-zirconium alloys SO SCRIPTA MATERIALIA LA English DT Article DE indentation size effect; hardness; nanoindention; aluminum; nanocrystalline aluminum-zirconium; contact stiffness ID STRAIN GRADIENT PLASTICITY; SINGLE-CRYSTALS; HARDNESS C1 Univ Wisconsin, Madison, WI USA. Argonne Natl Lab, Div Sci Mat, Argonne, IL 60439 USA. Northwestern Univ, Evanston, IL USA. RP Elmustafa, AA (reprint author), NASA, Langley Res Ctr, Ctr Adv Computat Technol, UVA, Mail Stop 201, Hampton, VA 23681 USA. RI Weertman, Julia/B-7540-2009; Eastman, Jeffrey/E-4380-2011; Stone, Donald/A-7496-2016; OI Eastman, Jeff/0000-0002-0847-4265 NR 18 TC 32 Z9 33 U1 1 U2 15 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 1359-6462 J9 SCRIPTA MATER JI Scr. Mater. PD OCT 30 PY 2000 VL 43 IS 10 BP 951 EP 955 DI 10.1016/S1359-6462(00)00520-0 PG 5 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA 373AK UT WOS:000165266100014 ER EF