FN Thomson Reuters Web of Science™ VR 1.0 PT J AU Lau, AS Ramirez, J Pruitt, S Zirkle-Yoshida, M Girten, B AF Lau, AS Ramirez, J Pruitt, S Zirkle-Yoshida, M Girten, B TI Effects of cage type and NASA rodent food bar in male Sprague-Dawley rats SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Lockheed Martin, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Foothill DeAnza Internship Program, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Ohio State Univ, Columbus, OH 43210 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A1113 EP A1113 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202308 ER PT J AU Liang, MTC Cleek, T Vu, V Navidi, M Whalen, R Arnaud, SB AF Liang, MTC Cleek, T Vu, V Navidi, M Whalen, R Arnaud, SB TI Torsional bone strength of young growing & mature rats SO FASEB JOURNAL LA English DT Meeting Abstract C1 Calif State Polytech Univ Pomona, Pomona, CA 91768 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A1112 EP A1112 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202302 ER PT J AU Meck, JV Waters, WW D'Aunno, DS Lodato, RF Perez, SA Ziegler, MG Huang, PL deBlock, HF AF Meck, JV Waters, WW D'Aunno, DS Lodato, RF Perez, SA Ziegler, MG Huang, PL deBlock, HF TI Hemodynamic responses to IV tyramine before and after spaceflight. SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Baylor Coll Med, Houston, TX 77030 USA. Univ Texas, Houston, TX USA. Wyle Labs, Houston, TX USA. Univ Calif San Diego, San Diego, CA 92103 USA. Harvard Univ, Sch Med, Boston, MA USA. Albany Med Coll, Albany, NY 12208 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A777 EP A777 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200367 ER PT J AU Mills, NA Baer, LA Ronca, AE AF Mills, NA Baer, LA Ronca, AE TI Effects of 2.0-g, 1.75-g and 1.5-g hypergravity on pregnancy outcome in rats SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Calif Davis, Davis, CA 95616 USA. Lockeed Martin, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A795 EP A795 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200476 ER PT J AU Ronca, AE Baer, LA Plaut, K Wade, CE AF Ronca, AE Baer, LA Plaut, K Wade, CE TI Body weight gain during a discrete nursing episode in suckling rats reared at 1.75-g or 1.5-g exceeds that of 1.0-g controls and is independent of maternal hypergravity exposure SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Lockheed Martin, Moffett Field, CA 94035 USA. Univ Vermont, Burlington, VT 05405 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A796 EP A796 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200477 ER PT J AU Rossum, AC Meck, JV AF Rossum, AC Meck, JV TI Comparison of pre- and post-spaceflight responses to standing in an elderly and younger astronauts. SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Kelsey Sebold, 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 FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A777 EP A777 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200366 ER PT J AU Schneider, S Lee, SMC Boda, W Langemack, A Watenpaugh, D Hargens, A AF Schneider, S Lee, SMC Boda, W Langemack, A Watenpaugh, D Hargens, A TI Treadmill exercise against LBNP during a 30-d bed rest maintains leg strength and endurance SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, SD3, Houston, TX 77058 USA. Wyle Labs, Houston, TX 77058 USA. Sonoma State Univ, Sonoma, CA USA. Univ Calif San Diego, San Diego, CA 92103 USA. Univ N Texas, Dallas, TX USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A1111 EP A1111 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202293 ER PT J AU Smith, SM Fesperman, JV DeKerlegand, DE Davis-Street, JE Hargens, A AF Smith, SM Fesperman, JV DeKerlegand, DE Davis-Street, JE Hargens, A TI Countering weightlessness-induced bone loss: treadmill exercise within lower body negative pressure (LBNP) alters markers of bone and calcium metabolism. SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Enterprise Advisory Serv Inc, Houston, TX 77058 USA. Univ Calif San Diego, La Jolla, CA 92093 USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A1111 EP A1111 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202296 ER PT J AU Smith, SM Nillen, JL Davis-Street, JB DeKerlegand, DE LeBlanc, A Shackelford, LC AF Smith, SM Nillen, JL Davis-Street, JB DeKerlegand, DE LeBlanc, A Shackelford, LC TI Alendronate and resistive exercise countermeasures against bed rest induced bone loss: Biochemical markers of bone and calcium metabolism. SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Enterprise Advisory Serv Inc, Houston, TX 77058 USA. Baylor Coll Med, Houston, TX 77030 USA. NR 0 TC 3 Z9 3 U1 1 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A1096 EP A1096 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202214 ER PT J AU Smith, SM Morukov, B Nillen, JL Davis-Street, JE DeKerlegand, DE Larina, I Oganov, V Shackelford, LC AF Smith, SM Morukov, B Nillen, JL Davis-Street, JE DeKerlegand, DE Larina, I Oganov, V Shackelford, LC TI Bone resorption after extended-duration spaceflight: Results of studies from the Mir Space Station. SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Inst Biomed Problems, Moscow, Russia. Enterprise Advisory Serv Inc, Houston, TX USA. NR 0 TC 3 Z9 3 U1 1 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A1096 EP A1096 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202211 ER PT J AU Stein, TP Schluter, MD Moran, MM Wang, TJ Grindeland, RE Wade, CE AF Stein, TP Schluter, MD Moran, MM Wang, TJ Grindeland, RE Wade, CE TI Impact of hind limb unloading on gene expression by skeletal muscle SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Med & Dent New Jersey, Sch Osteopath Med, Stratford, NJ 08084 USA. NASA, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A1112 EP A1112 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202303 ER PT J AU Wade, CE Moran, MM Wang, TJ Baer, LA Yuan, F Fung, CK Stein, TP AF Wade, CE Moran, MM Wang, TJ Baer, LA Yuan, F Fung, CK Stein, TP TI Body mass changes associated with hyper-gravity are independent of adrenal derived hormones SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Lockheed Martin, Moffett Field, CA 94035 USA. Univ Med & Dent New Jersey, Sch Osteopath Med, Dept Surg, Stratford, NJ 08084 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A796 EP A796 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200481 ER PT J AU Watenpaugh, DE O'Leary, DD Lee, SMC Hughson, RL Shoemaker, JK Langemack, A Steinbach, G Kawai, Y Schneider, SM Hargens, AR AF Watenpaugh, DE O'Leary, DD Lee, SMC Hughson, RL Shoemaker, JK Langemack, A Steinbach, G Kawai, Y Schneider, SM Hargens, AR TI Brief daily post-exercise resting LBNP protects orthostatic tolerance during bed rest SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ N Texas, Hlth Sci Ctr, Ft Worth, TX 76107 USA. Univ Waterloo, Waterloo, ON N2L 3G1, Canada. NASA, JSC, Houston, TX 77058 USA. Univ Western Ontario, London, ON, Canada. Univ Calif San Diego, La Jolla, CA 92093 USA. Tottori Univ, Tottori 680, Japan. NR 0 TC 1 Z9 1 U1 0 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A1110 EP A1110 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454202291 ER PT J AU Waters, WW Meck, JV AF Waters, WW Meck, JV TI Low total peripheral resistance, not stroke volume or plasma volume, separate presyncopal and non-presyncopal astronauts following spaceflight SO FASEB JOURNAL LA English DT Meeting Abstract C1 Baylor Coll Med, Natl Space Biomed Res Inst, Houston, TX 77030 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A777 EP A777 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454200369 ER PT J AU Yamauchi, K Kulkarni, AD Ramesh, V Hales, N Pellis, NR AF Yamauchi, K Kulkarni, AD Ramesh, V Hales, N Pellis, NR TI Lack of inflammatory cell mediated responses in anti-orthostatic suspension (AOS) induced simulated microgravity. SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Texas, Hlth Sci Ctr, Houston, TX 77030 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A1035 EP A1035 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454201858 ER PT J AU Yu, DS Dalton, BP Barrett, JE AF Yu, DS Dalton, BP Barrett, JE TI Long-term rat nutrition studies: NASA Food Bar versus Purina Lab Chow SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Lockheed Martin, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 8 PY 2001 VL 15 IS 5 BP A960 EP A960 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410TA UT WOS:000167454201423 ER PT J AU Kane, SM Leu, MT AF Kane, SM Leu, MT TI Uptake of methanol vapor in sulfuric acid solutions SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID UPPER TROPOSPHERE; DIMETHYL SULFATE; STRATOSPHERE AB The uptake of gas-phase methanol by liquid sulfuric acid has been investigated over the composition range of 40-85 wt % H2SO4 and the temperature range of 210-235 K. Laboratory studies were performed with a flow-tube reactor coupled to an electron-impact ionization mass spectrometer to detect trace gases. While reversible uptake was the primary mechanism at low acid concentrations, an irreversible reaction between methanol and sulfuric acid at low temperatures, forming methyl hydrogen sulfate and dimethyl sulfate, was observed at all concentrations. At compositions >65 wt % H2SO4, more than 90% of uptake was found to be reactive. On the basis of the uptake data and the calculated liquid-phase diffusion coefficients, the product of the effective Henry's law constant (H*) and the square root of the overall liquid-phase reaction rate (k(1)) was calculated as a function of acid concentration and temperature. The results suggest that the reaction with sulfuric acid forming methyl hydrogen sulfate and dimethyl sulfate is the dominant loss mechanism of methanol and that the oxidation of methanol is only a minor source of hydroxyl radicals in the upper troposphere. C1 CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. RP Leu, MT (reprint author), CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. NR 30 TC 26 Z9 26 U1 0 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 MAR 8 PY 2001 VL 105 IS 9 BP 1411 EP 1415 DI 10.1021/jp001707a PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 407JN UT WOS:000167268600002 ER PT J AU Perkins, KK Hanisco, TF Cohen, RC Koch, LC Stimpfle, RM Voss, PB Bonne, GP Lanzendorf, EJ Anderson, JG Wennberg, PO Gao, RS Del Negro, LA Salawitch, RJ McElroy, CT Hintsa, EJ Loewenstein, M Bui, TP AF Perkins, KK Hanisco, TF Cohen, RC Koch, LC Stimpfle, RM Voss, PB Bonne, GP Lanzendorf, EJ Anderson, JG Wennberg, PO Gao, RS Del Negro, LA Salawitch, RJ McElroy, CT Hintsa, EJ Loewenstein, M Bui, TP TI The NOx-HNO3 system in the lower stratosphere: Insights from in situ measurements and implications of the J(HNO3)-[OH] relationship SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID SUMMER POLARIS MISSION; NASA ER-2 AIRCRAFT; REACTIVE NITROGEN; ARCTIC STRATOSPHERE; SOUTHERN-HEMISPHERE; MIDDLE STRATOSPHERE; OZONE LOSS; NO2; CLO; PHOTOCHEMISTRY AB During the 1997 Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission, simultaneous in situ observations of NOchi and HOchi radicals, their precursors, and the radiation field were obtained in the lower stratosphere. We use these observations to evaluate the primary mechanisms that control NOchi- HNO3 exchange and to understand their control over the partitioning between NO2 and HNO3 in regions of continuous sunlight. We calculate NOchi production (P-NO chi) and loss (L-NO chi) in a manner directly constrained by the in situ measurements and current rate constant recommendations, using approaches for representing albedo, overhead O-3 and [OH] that reduce model uncertainty. We find a consistent discrepancy of 18% between modeled rates of NOchi production and loss (L-NO chi = 1.18P(NO chi)) which is within the measurement uncertainty of 127%. The partitioning between NOchi production processes is [HNO3 + OH (41 +/- 2)%; HNO3 + hv (59 +/- 2)%] and between NOchi loss processes is [NO2 + OH, 90% to > 97%; BrONO2 + H2O, 10% to <3%]. The steady-state description of NOchi-HNO3 exchange reveals the significant influence of the tight correlation between the photolysis rate of HNO3 and [OH] established by in situ measurements throughout the lower stratosphere. Parametrizing this relationship, we find (I)the steady-state value of [NO2](24h-avg)/[HNO3] in the continuously sunlit, lower stratosphere is a function only of temperature acid number density, and (2) the partitioning of NO, production between HNO3 + OH and HNO3 + hv is nearly constant throughout most of the lower stratosphere. We describe a methodology (functions of latitude, day, temperature, and pressure) for accurately predicting the steady-state value of [NO2](24h-avg)/[HNO3] and the partitioning of NOchi production within these regions. The results establish a metric to compare observations of [NO2](24h-avg)/[HNO3] within the continuously sunlit region and provide a simple diagnostic for evaluating the accuracy of models that attempt to describe the coupled NOchi-HOchi photochemistry in the lower stratosphere. C1 Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02138 USA. Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA. Univ Calif Berkeley, Dept Geol & Geophys, Berkeley, CA 94720 USA. CALTECH, Div Engn, Pasadena, CA 91125 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. NOAA, Aeron Lab, Boulder, CO 80303 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Environm Canada, Meteorol Serv Canada, Downsview, ON, Canada. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Perkins, KK (reprint author), Harvard Univ, Dept Chem & Biol Chem, 12 Oxford St, Cambridge, MA 02138 USA. RI Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Wennberg, Paul/A-5460-2012; Gao, Ru-Shan/H-7455-2013; Bonne, Gisele/G-3121-2013 OI Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; NR 56 TC 20 Z9 20 U1 0 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 MAR 8 PY 2001 VL 105 IS 9 BP 1521 EP 1534 DI 10.1021/jp002519n PG 14 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 407JN UT WOS:000167268600016 ER PT J AU Lanzendorf, EJ Hanisco, TF Wennberg, PO Cohen, RC Stimpfle, RM Anderson, JG Gao, RS Margitan, JJ Bui, TP AF Lanzendorf, EJ Hanisco, TF Wennberg, PO Cohen, RC Stimpfle, RM Anderson, JG Gao, RS Margitan, JJ Bui, TP TI Establishing the dependence of [HO2]/[OH]] on temperature, halogen loading, O-3, and NOx based on in situ measurements from the NASA ER-2 SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID LOWER STRATOSPHERE; INSITU MEASUREMENTS; UPPER TROPOSPHERE; 72-DEGREES-S LATITUDE; REACTIVE NITROGEN; OH; AIRCRAFT; HO2; CHEMISTRY; PHOTOCHEMISTRY AB In situ observations of OH and HO2 from the Airborne Southern Hemisphere Ozone Experiment/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA), Stratospheric TRacers of Atmospheric Transport (STRAT), and Polar Ozone Loss in the Arctic Region in Summer (POLARIS) NASA ER-2 field campaigns are used to examine the partitioning of HOchi in the lower stratosphere (tropopause to similar to 21 km) and upper troposphere (similar to 10 km to tropopause). These measurements span a latitude range from 70 degreesS to 90 degreesN and a variety of atmospheric conditions as a result of seasonal changes and altitude. The response of the observed [HO2]/[OH] to changes in temperature, [O-3], [CO], [NO], [CIO], and [BrO] is investigated. The measured ratio is accurately described (similar to+/-10%) by a steady-state model constrained by the measured mixing ratios of O-3, CO, NO, CIO, and BrO, where the model is valid for conditions of HOchi, cycling much faster than HOchi production and loss. The concentration of HO2 depends on [OH], which, to first order, has been observed to be a simple function of the solar zenith angle in the lower stratosphere.(1) The partitioning between OH and HO2 is controlled by the local chemistry between the HOchi radicals and O-3, CO, NO, CIO, and BrO. The response of [HOchi] to changes in [NOchi] and [O-3] is demonstrated. Further observations are necessary to illustrate the response of HOchi to changes in halogen concentrations. A quantitative understanding of [HO2]/ [OH] is important, since many of the reactions that control this ratio are directly involved in catalytic removal of O-3 in the lower stratosphere and production of O-3 in the upper troposphere. C1 Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02138 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Div Engn, Pasadena, CA 91125 USA. Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA. NOAA, Aeron Lab, Boulder, CO 80303 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Lanzendorf, EJ (reprint author), Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02138 USA. RI Cohen, Ronald/A-8842-2011; Wennberg, Paul/A-5460-2012; Gao, Ru-Shan/H-7455-2013 OI Cohen, Ronald/0000-0001-6617-7691; NR 29 TC 12 Z9 12 U1 0 U2 8 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 MAR 8 PY 2001 VL 105 IS 9 BP 1535 EP 1542 DI 10.1021/jp0023841 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 407JN UT WOS:000167268600017 ER PT J AU Hanisco, TF Lanzendorf, EJ Wennberg, PO Perkins, KK Stimpfle, RM Voss, PB Anderson, JG Cohen, RC Fahey, DW Gao, RS Hintsa, EJ Salawitch, RJ Margitan, JJ McElroy, CT Midwinter, C AF Hanisco, TF Lanzendorf, EJ Wennberg, PO Perkins, KK Stimpfle, RM Voss, PB Anderson, JG Cohen, RC Fahey, DW Gao, RS Hintsa, EJ Salawitch, RJ Margitan, JJ McElroy, CT Midwinter, C TI Sources, sinks, and the distribution of OH in the lower stratosphere SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID IN-SITU OBSERVATIONS; SOUTHERN-HEMISPHERE; ARCTIC REGION; OZONE LOSS; PHOTOCHEMISTRY; AIRCRAFT; SUMMER; NO2; CHLORINE; RADICALS AB Extensive measurement campaigns by the NASA ER-2 research aircraft have obtained a nearly pole-to-pole database of the species that control HOchi (OH + HO2) chemistry. The wide dynamic range of these in situ measurements provides an opportunity to demonstrate empirically the mechanisms that control the HOchi system. Measurements in the lower stratosphere show a remarkably tight correlation of OH concentration with the solar zenith angle (SZA). This correlation is nearly invariant over latitudes ranging from 70 degrees S to 90 degrees N and all seasons. An analysis of the production and loss of HOchi in terms of the rate determining steps of reaction sequences developed by Johnston and Podolske and Johnston and Kinnison is used to clarify the behavior of the system and to directly test our understanding of the system with observations. Calculations using in situ measurements show that the production rate of HOchi is proportional to O-3 and ultraviolet radiation flux. The loss rate is proportional to the concentration and the partitioning of NO, (reactive nitrogen) and the concentration of HO2. In the absence of heterogeneous reactions, the partitioning of NOgamma is controlled by O-3 and HOchi and the concentration of HO2 is controlled by NOgamma and O-3, so that the removal rate of OH is buffered against changes in the correlation of O-3 and NOgamma. The heterogeneous conversion of NO2 to HNO3 is not an important net source of HOchi because production and removal sequences are nearly balanced. Changes in NOgamma partitioning resulting from heterogeneous chemistry have a large effect on the loss rates of HOchi, but little or no impact on the measured abundance of OH. The enhanced loss rates at high NO2/HNO3 are offset in the data set examined here by enhanced production rates resulting from increased photolysis rates resulting from the decreased O-3 column above the ER-2. C1 Harvard Univ, Dept Chem, Cambridge, MA 02138 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Calif Berkeley, Berkeley, CA 94720 USA. NOAA, Aeron Lab, Boulder, CO 80303 USA. NOAA, Boulder, CO USA. Woods Hole Oceanog Inst, Woods Hole, MA 02543 USA. Atmospher Environm, Downsview, ON, Canada. RP Hanisco, TF (reprint author), Harvard Univ, Dept Chem, 12 Oxford St, Cambridge, MA 02138 USA. RI Fahey, David/G-4499-2013; Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Wennberg, Paul/A-5460-2012; Gao, Ru-Shan/H-7455-2013 OI Fahey, David/0000-0003-1720-0634; Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; NR 25 TC 21 Z9 21 U1 0 U2 17 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 MAR 8 PY 2001 VL 105 IS 9 BP 1543 EP 1553 DI 10.1021/jp002334g PG 11 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 407JN UT WOS:000167268600018 ER PT J AU Roehl, CM Mazely, TL Friedl, RR Li, YM Francisco, JS Sander, SP AF Roehl, CM Mazely, TL Friedl, RR Li, YM Francisco, JS Sander, SP TI NO2 quantum yield from the 248 nm photodissociation of peroxynitric acid (HO2NO2) SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID PERNITRIC ACID; PEROXYACETYL NITRATE; AB-INITIO; INTENSITIES; ABSORPTION; PHOTOLYSIS; OVERTONES; SPECTRA; BAND; 2ND AB Peroxynitric acid (PNA) was photolyzed at 248 nm, and the NO2 photoproduct was detected by laser-induced fluorescence (LIF). The quantum yield for the production of NO2 was determined by comparison with HNO3 photolysis data taken under identical experimental conditions. Measurements made over a range of pressures, flows, and precursor concentrations resulted in an NO2 quantum yield of 0.56 +/- 0.17, where the statistical uncertainty is 2 standard deviations. Calculations of potential energy curves for several low-lying singlet and triplet states of PNA are presented. The calculations show that while the singlet excitations occur via an n-pi* transition on the NO2 moiety, the dissociative channels forming OH + NO3 and HO2 + NO2 likely occur via predissocation on different surfaces, Excitation energies at the MRCI and CCSD(T) level of theory show that excited states of PNA are not accessible at wavelengths longer than 407 nm (similar to3.0 eV). C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Dept Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. RP Sander, SP (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 183-901, Pasadena, CA 91109 USA. NR 32 TC 15 Z9 15 U1 0 U2 4 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 MAR 8 PY 2001 VL 105 IS 9 BP 1592 EP 1598 DI 10.1021/jp001982x PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 407JN UT WOS:000167268600024 ER PT J AU Klemm, RB Thorn, RP Stief, LJ Buckley, TJ Johnson, RD AF Klemm, RB Thorn, RP Stief, LJ Buckley, TJ Johnson, RD TI Heat of formation of OBrO: Experimental photoionization study SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID JANAF THERMOCHEMICAL TABLES; IONIZATION-ENERGY; EFFICIENCY SPECTRUM; OZONE DEPLETION; BROMINE DIOXIDE; AB-INITIO; 298 K; RADICALS; OXIDES; IODINE AB The appearance energy of BrO+ from the dissociative ionization of OBrO was determined from the photoionization efficiency spectrum of BrO+ over the wavelength range lambda = 90-122 nm by using a discharge flow-photoionization mass spectrometer apparatus coupled to a vacuum- ultraviolet synchrotron radiation source. Bromine dioxide was generated in a flow tube reactor by first forming BrO via the reaction O(P-3) + Br-2 and then allowing the BrO to react on the cold flow tube wall. Species present in addition to OBrO were BrO, HOBr, Br2O, and residual BT2. The results are perturbed by a signal from BrO+ formed by direct photoionization of BrO and by the dissociative ionization of Br2O. It was possible to correct for these perturbations to obtain a clean appearance energy plot that yielded a threshold at lambda = 98.65 +/- 0.23 nm. This gives AE(298)(BrO+,OBrO) = 12.56(8) +/- 0.02(9) eV. Taking known thermodynamic quantities, this result yields Delta H-f(0)o(OBrO) = 173.4 +/- 4.3 kJ mol(-1) (and Delta H-f(298)o(OBrO) = 163.9 +/- 4.4 kJ mol(-1)). This is the first experimental determination of the heat of formation of OBrO, and the present result is compared with those of previous estimates and recent calculations. In addition, computations (based on results from ab initio calculations) were performed to obtain Delta H-f(0)o(OBrO) = 164 +/- 8 kJ mol(-1), which is in very good agreement with our experimental result. Also, a value for Delta H-f(0)o(OIO) of 174 +/- 25 kJ mol(-1) was estimated from a trend analysis that employed Chase's method (i.e., Delta H-at(0)o(OXO)/D-0(o)(XO)). Additionally, a comparison is made of recent photoelectron spectroscopic and photoionization mass spectrometric determinations of the ionization energies of BrO and OBrO. C1 Brookhaven Natl Lab, Upton, NY 11973 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Natl Inst Stand & Technol, Phys & Chem Properties Div, Gaithersburg, MD 20899 USA. RP Klemm, RB (reprint author), Brookhaven Natl Lab, Bldg 815,POB 5000, Upton, NY 11973 USA. NR 44 TC 13 Z9 13 U1 1 U2 3 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 MAR 8 PY 2001 VL 105 IS 9 BP 1638 EP 1642 DI 10.1021/jp002397z PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 407JN UT WOS:000167268600030 ER PT J AU Xiea, W Pan, WP Chuang, KC AF Xiea, W Pan, WP Chuang, KC TI Thermal characterization of PMR polyimides SO THERMOCHIMICA ACTA LA English DT Article; Proceedings Paper CT 27th North-American-Thermal-Analysis-Society Conference CY SEP 20-22, 1999 CL SAVANNAH, GEORGIA SP N Amer Thermal Anal Soc DE polyimide; TGA/FTIR/MS; degradation mechanism AB Polyimides are attractive for high temperature applications as the matrix resins, due to their excellent thermo-oxidative stability and mechanical properties. As composite materials for aerospace applications, they possess certain unique characteristics such as toughness, resistance to temperature and solvents as well as high tensile strength and modulus. A series of novel PMR polyimides based on substituted benzidines are examined and compared to the state-of-the-art PMR-15. The assigned glass transition temperatures and the mechanism for the thermal decomposition of four specific PMR polyimides are obtained, using thermal mechanical analysis and TGA/FTIR/MS techniques, Their thermal decomposition steps are proposed, identified and also compared to each other. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Western Kentucky Univ, Dept Chem, Thermal Anal Lab, Bowling Green, KY 42101 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Xiea, W (reprint author), Western Kentucky Univ, Dept Chem, Thermal Anal Lab, Bowling Green, KY 42101 USA. NR 9 TC 1 Z9 1 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-6031 J9 THERMOCHIM ACTA JI Thermochim. Acta PD MAR 8 PY 2001 VL 367 BP 143 EP 153 PG 11 WC Thermodynamics; Chemistry, Analytical; Chemistry, Physical SC Thermodynamics; Chemistry GA 414FU UT WOS:000167656100020 ER PT J AU Kulkarni, AD Yamauchi, K Ramesh, V Ramesh, GT Bhuiyan, MBA Mailman, D Pellis, NR AF Kulkarni, AD Yamauchi, K Ramesh, V Ramesh, GT Bhuiyan, MBA Mailman, D Pellis, NR TI Nitric oxide (NO) & inducible nitric oxide synthase (iNOS) and their correlation to immune function in simulated microgravity. SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Texas, Hlth Sci Ctr, Houston, TX USA. Texas So Univ, Houston, TX 77004 USA. Univ Houston, Houston, TX USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 7 PY 2001 VL 15 IS 4 BP A338 EP A338 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410KA UT WOS:000167438101935 ER PT J AU Maple, R Ronca, A Baer, L Wade, C Plaut, K AF Maple, R Ronca, A Baer, L Wade, C Plaut, K TI Effects of hypergravity on mammary metabolism in pregnant rats SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Vermont, Burlington, VT 05405 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 1 Z9 1 U1 0 U2 2 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 7 PY 2001 VL 15 IS 4 BP A69 EP A69 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410KA UT WOS:000167438100388 ER PT J AU Ortiz, RM Wade, CE Ortiz, CL AF Ortiz, RM Wade, CE Ortiz, CL TI Renal function in naturally fasting northern elephant seal pups SO FASEB JOURNAL LA English DT Meeting Abstract C1 Univ Calif Santa Cruz, Santa Cruz, CA 95064 USA. NASA, Ames Res Ctr, Div Life Sci, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 1 U2 3 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 7 PY 2001 VL 15 IS 4 BP A411 EP A411 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410KA UT WOS:000167438102347 ER PT J AU Ramirez, JL Zirkle-Yoshida, MM Piert, S Barrett, J Yu, D Dalton, B Girten, B AF Ramirez, JL Zirkle-Yoshida, MM Piert, S Barrett, J Yu, D Dalton, B Girten, B TI The effects of long-term feeding of rodent food bars on lipid peroxidation and antioxidant enzyme levels in Fisher rats SO FASEB JOURNAL LA English DT Meeting Abstract C1 Lockheed Martin, Ames Res Ctr, Moffett Field, CA 94035 USA. Adecco, Moffett Field, CA USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 7 PY 2001 VL 15 IS 4 BP A84 EP A84 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA 410KA UT WOS:000167438100474 ER PT J AU Joy, M Carlstrom, JE AF Joy, M Carlstrom, JE TI Cosmology - Probing the early universe with the SZ effect SO SCIENCE LA English DT Editorial Material ID SPECTRUM C1 NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Joy, M (reprint author), NASA, George C Marshall Space Flight Ctr, Dept Space Sci, SD50, Huntsville, AL 35812 USA. NR 17 TC 2 Z9 3 U1 0 U2 0 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 MAR 2 PY 2001 VL 291 IS 5509 BP 1715 EP + DI 10.1126/science.291.5509.1715 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 408HK UT WOS:000167320600035 PM 11253197 ER PT J AU Fox, JJ Gormley, TJ AF Fox, JJ Gormley, TJ TI Informed maintenance for next generation reusable launch systems SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL AB Perhaps the most substantial single obstacle to progress of space exploration and utilization of space for human benefit is the safety & reliability and the inherent cost of launching to, and returning from, space. The primary influence in the high costs of current launch systems (the same is true for commercial and military aircraft and most other reusable systems) is the operations, maintenance and infrastructure portion of the program's total life cycle costs. Reusable Launch Vehicle (RLV) maintenance and design have traditionally been two separate engineering disciplines with often conflicting objectives - maximizing ease of maintenance versus optimizing performance, size and cost. Testability analysis, an element of Informed Maintenance (IM), has been an ad hoc, manual effort, in which maintenance engineers attempt to identify an efficient method of troubleshooting for the given product, with little or no control over product design. Therefore, testability deficiencies in the design cannot be rectified. It is now widely recognized that IM must be engineered into the product at the design stage itself, so that an optimal compromise is achieved between system maintainability and performance. The elements of IM include testability analysis, diagnostics/prognostics, automated maintenance scheduling, automated logistics coordination, paperless documentation and data mining. IM derives its heritage from complimentary NASA science, space and aeronautic enterprises such as the on-board autonomous Remote Agent Architecture recently flown on NASA's Deep Space 1 Probe as well as commercial industries that employ quick turnaround operations. Commercial technologies and processes supporting NASA's IM initiatives include condition based maintenance technologies from Boeing's Commercial 777 Aircraft and Lockheed-Martin's F-22 Fighter, automotive computer diagnostics and autonomous controllers that enable 100,000 mile maintenance free operations, and locomotive monitoring system software. This paper will summarize NASA's long-term strategy, development, and implementation plans for Informed Maintenance for next generation RLVs. This will be done through a convergence into a single IM vision the work being performed throughout NASA, industry and academia. Additionally, a current status of IM development throughout NASA programs such as the Space Shuttle, X-33, X-34 and X-37 will be provided and will conclude with an overview of near-term work that is being initiated in FY00 to support NASA's 2(nd) Generation Reusable Launch Vehicle Program. (C) 2001 AIAA. Published by Elsevier Science Ltd. C1 NASA, Kennedy Space Ctr, Kennedy Space Ctr, FL 32899 USA. RP Fox, JJ (reprint author), NASA, Kennedy Space Ctr, Kennedy Space Ctr, FL 32899 USA. NR 12 TC 1 Z9 2 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 439 EP 449 DI 10.1016/S0094-5765(01)00064-9 PG 11 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000019 ER PT J AU Newman, JS AF Newman, JS TI Failure-space - A systems engineering look at 50 space system failures SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL AB Multiple perspectives are presented on failure-event-chain analysis and failure cause categorization followed by description of a systems engineering framework for failure evaluation. The framework consists of engineering and organizational elements typically within the program manager span of control. The systems engineering lens is then used to evaluate 50 space system failures. The high level mapping of failure attributes (causal root structure) indicates the need for across the board systems engineering rigor. That is, failure can propagate from virtually every critical activity in a space system life cycle. Analysis results show strong implication of design, design verification & test, manufacturing/production, and manufacturing/production verification & test as recurrent causal factors in space system failures. The Failure Space perspective reminds one of the need for thorough and complete risk management and assurance process implementation over the life of a project as well as, increased emphasis on lessons learned and recurrent monitoring of critical process fidelity. (C) 2001 AIAA. Published by Elsevier Science Ltd. C1 NASA, Washington, DC 20546 USA. RP Newman, JS (reprint author), NASA, Washington, DC 20546 USA. NR 17 TC 10 Z9 10 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 517 EP 527 DI 10.1016/S0094-5765(01)00071-6 PG 11 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000027 ER PT J AU van Zyl, JJ AF van Zyl, JJ TI The Shuttle Radar Topography Mission (SRTM): A breakthrough in remote sensing of topography SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL ID INTERFEROMETER AB The Shuttle Radar Topography Mission (SRTM), flown on the Space Shuttle Endeavour on Flight STS-99 and launched on Il February 2000, will produce digital elevation data of the Earth's land mass between 60 degrees north latitude and 54 degrees south latitude. This data will be at least one order of magnitude more precise in the elevation resolution, and will have postings of 30 m, representing an order of magnitude increase in the density of the postings over currently available data. (C) 2001 AIAA. Published by Elsevier Science Ltd. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP van Zyl, JJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Namikawa, Laercio/C-5559-2013 OI Namikawa, Laercio/0000-0001-7847-1804 NR 8 TC 75 Z9 78 U1 2 U2 12 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 559 EP 565 DI 10.1016/S0094-5765(01)00020-0 PG 7 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000031 ER PT J AU Lee, MC Israelsson, UE AF Lee, MC Israelsson, UE TI New microgravity fundamental physics research areas in the ISS era SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL AB NASA's microgravity fundamental physics program has used the Space Shuttle to perform high resolutions experiments in space. As we come to the end of the Shuttle era, we will begin to perform research aboard the ISS. A large stable of ground based experiments have been selected from NASA Research Announcements in a variety of disciplines. These investigations will form the backbone from which to select future night candidates. Research in Laser Cooling and Atomic Physics will enable us to operate highly precise docks in space. Low temperature physics experiments will use a liquid helium facility with a six-month lifetime. This facility can also support experiments in gravitational physics. Researchers in biological physics will be offered an opportunity to develop future experiments that can benefit from space experimentation. An overview of the future research directions and the benefits to the community of performing research aboard the ISS will be presented. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Headquarters, Washington, DC 20546 USA. RP Lee, MC (reprint author), NASA, Headquarters, 300 E St SW, Washington, DC 20546 USA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 597 EP 602 DI 10.1016/S0094-5765(01)00029-7 PG 6 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000035 ER PT J AU Edwards, CD Adams, JT Bell, DJ Cesarone, R DePaula, R Durning, JF Ely, TA Leung, RY McGraw, CA Rosell, SN AF Edwards, CD Adams, JT Bell, DJ Cesarone, R DePaula, R Durning, JF Ely, TA Leung, RY McGraw, CA Rosell, SN TI Strategies for telecommunications and navigation in support of Mars exploration SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL AB The planned exploration of Mars will pose new and unique telecommunciations and navigation challenges. The full range of orbital, atmospheric, and surface exploration will drive requirements on data return, energy-efficient communications, connectivity, and positioning. In this paper we will summarize the needs of the currently planned Mars exploration mission set, outline design trades and options for meeting these needs, and quantify the specific telecommunications and navigation capabilities of an evolving infrastructure. (C) 2001 AIAA. Published by Elsevier Science Ltd. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Edwards, CD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 9 TC 6 Z9 6 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 661 EP 668 DI 10.1016/S0094-5765(01)00042-X PG 8 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000042 ER PT J AU Rayman, MD Varghese, P AF Rayman, MD Varghese, P TI The Deep Space 1 extended mission SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL ID TECHNOLOGY VALIDATION MISSION AB The primary mission of Deep Space 1 (DS1), the first flight of the New Millennium program, completed successfully in September 1999, having exceeded its objectives of resting new, high-risk technologies important for future space and Earth science missions. DS1 is now in its extended mission, with plans to take advantage of the advanced technologies, including solar electric propulsion, to conduct an encounter with comet 19P/Borrelly in September 2001. During the extended mission, the spacecraft's commercial star tracker failed; this critical loss prevented the spacecraft from achieving three-axis attitude control or knowledge. A two-phase approach to recovering the mission was undertaken. The first involved devising a new method of pointing the high-gain antenna to Earth using the radio signal received at the Deep Space Network as an indicator of spacecraft attitude. The second was the development of new flight software that allowed the spacecraft to return to three-axis operation without substantial ground assistance. The principal new feature of this software is the use of the science camera as an attitude sensor. The differences between the science camera and the star tracker have important implications not only for the design of the new software but also for the methods of operating the spacecraft and conducting the mission. The ambitious rescue was fully successful, and the extended mission is back on track. (C) 2001 AIAA. Published by Elsevier Science Ltd. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Rayman, MD (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 20 Z9 21 U1 1 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 693 EP 705 DI 10.1016/S0094-5765(01)00044-3 PG 13 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000045 ER PT J AU Uri, JJ Lebedev, ON AF Uri, JJ Lebedev, ON TI Phase 1 research program overview SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL AB The Phase 1 research program was unprecedented in its scope and ambitious in its objectives. The National Aeronautics and Space Administration committed to conducting a multidisciplinary long-duration research program on a platform whose capabilities were not well known, not to mention belonging to another country. For the United States, it provided the first opportunity to conduct research in a long-duration space flight environment since the Skylab program in the 1970's. Multiple technical as well as cultural challenges were successfully overcome through the dedicated efforts of a relatively small cadre of individuals. The program developed processes to successfully plan, train for and execute research in a long-duration environment, with significant differences identified from short-duration space flight science operations. Between August 1994 and June 1998, thousands of kilograms of research hardware was prepared and launched to Mir, and thousands of kilograms of hardware and data products were returned to Earth. More than 150 Principal Investigators from eight countries were involved in the program in seven major research disciplines: Advanced Technology; Earth Sciences; Fundamental Biology; Human Life Sciences; International Space Station Risk Mitigation; Microgravity; and Space Sciences. Approximately 75 long-duration investigations were completed on Mir, with additional investigations performed on the Shuttle flights that docked with Mir. The flight phase included the participation of seven US astronauts and 20 Russian cosmonauts. The successful completion of the Phase 1 research program not only resulted in high quality science return but also in numerous lessons learned to make the ISS experience more productive. The cooperation developed during the program was instrumental in its success. (C) 2001 AIAA. Published by Elsevier Science Ltd. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Uri, JJ (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. NR 0 TC 0 Z9 0 U1 2 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 845 EP 851 DI 10.1016/S0094-5765(01)00055-8 PG 7 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000059 PM 11858276 ER PT J AU Watzin, J AF Watzin, J TI Observations from over a decade of experience in developing faster, better, cheaper missions for the NASA Small Explorer Program SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL AB The Small Explorer (SMEX) Project at NASA Goddard Space Flight Center (GSFC) has accumulated nearly a decade of experience building missions with the underlying philosophy of "Faster, Better, Cheaper"(FBC). Five satellites are now successfully operating on-orbit with only one serious instrument anomaly. Together this Project has accumulated 14.6 years of on-orbit experience without a spacecraft bus failure. Additionally, this project, under the Explorer Technology Infusion effort, has developed a protoflight version of a 21(st) Century FBC spacecraft bus that has just completed environmental qualification and has been selected as the base spacecraft for NASA's Triana mission. Design and production of these six high performance spacecraft, in just ten years time, has provided a unique base of experience From which to draw lessons learned. This paper will discuss the fundamental practices that have been used by the SMEX Project in achieving this record of success. (C) 2001 AIAA. Published by Elsevier Science Ltd. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Watzin, J (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 2 TC 1 Z9 1 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 853 EP 858 DI 10.1016/S0094-5765(01)00060-1 PG 6 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000060 ER PT J AU Cook, S Dumbacher, D AF Cook, S Dumbacher, D TI NASA's integrated space transportation plan SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL AB Improvements in the safety, reliability and affordability of current and future space transportation systems must be achieved if NASA is to perform its mission and if the U.S. space industry is to reach its full potential. m response to Presidential Policy in 1994, NASA, working with our industrial partners, initiated several efforts including the X-33, X-34, X37 and Advanced Space Transportation programs with the goal of demonstrating the technologies that could enable these goals. We have learned that emerging technologies will enable the needed advancements but that more development along multiple, competing paths is needed. We have learned that developing requirements diligently and in partnership with industry will allow us to better converge with commercial capabilities. We have learned that commercial markets are not growing as fast as projected earlier, but there are still possibilities in the near-term to pursue alternate paths that can make access to space mole robust. The goal of transitioning NASA's space transportation needs to commercial launch vehicles remains the key aim of our efforts and will require additional investment to reduce business and technical risks to acceptable levels. In response, NASA, in 1999, developed a comprehensive, integrated strategy for achieving these goals. The objective of the Integrated Space Transportation Plan (ISTP) was to integrate NASA's diverse space transportation activities into a single, comprehensive and integrated investment plan. The ISTP is based on the following five tenets: Focus on safety, reliability, cost and NASA mission definition trades to meet NASA's space transportation needs and to maximize use of U.S, aerospace industry capabilities and commercial market convergence. Enable a competition at an acceptable level of risk for development of a 2nd generation Reusable Launch Vehicle (RLV) no later than 2005. Develop an integrated architecture that includes, where applicable, related system concepts to meet NASA-unique space transportation needs on a commercial RLV and potentially provide NASA assured access to space on more than one launch vehicle. Secure safe, reliable, and cost-effective access to space in the far-term through investments in 3rd generation RLV technologies for earth-to-orbit and in-space applications. Ensure continued safe access to space through Space Shuttle safety upgrades until a replacement alternative has been demonstrated The ISTP contains investment plans for Space Shuttle safety upgrades, Crew Return Vehicle for the International Space Station, Space Station Alternate Access, 2(nd) Generation RLV Risk Mitigation and, Aerospace Base Research and Technology. (C) 2001 International Astronautical Federation. Published by Elsevier Science Ltd. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Cook, S (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 0 TC 1 Z9 1 U1 1 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 869 EP 883 DI 10.1016/S0094-5765(01)00063-7 PG 15 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000062 ER PT J AU Garver, LB Crouch, MM AF Garver, LB Crouch, MM TI NASA strategic planning for 2000 and beyond SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 51st International Astronautical Federation Congress CY OCT 02-06, 2000 CL RIO JANEIRO, BRAZIL AB This short paper outlines the United States National Aeronautics and Space Administration's development of its 2000 Strategic Plan Published by Elsevier Science Ltd. C1 NASA, Washington, DC 20546 USA. RP Garver, LB (reprint author), NASA, Washington, DC 20546 USA. NR 0 TC 0 Z9 0 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR-JUN PY 2001 VL 48 IS 5-12 SI SI BP 895 EP 903 DI 10.1016/S0094-5765(01)00069-8 PG 9 WC Engineering, Aerospace SC Engineering GA 446TV UT WOS:000169531000064 PM 11858277 ER PT J AU Ciszak, E Korotchkina, LG Hong, YS Joachimiak, A Patel, MS AF Ciszak, E Korotchkina, LG Hong, YS Joachimiak, A Patel, MS TI Crystallization and initial X-ray diffraction analysis of human pyruvate dehydrogenase SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Article ID MULTIENZYME COMPLEX; PYROPHOSPHATE; BINDING AB Human pyruvate dehydrogenase (E1) is a component enzyme of the pyruvate dehydrogenase complex. The enzyme catalyzes the irreversible decarboxylation of pyruvic acid and the rate-limiting reductive acetylation of the lipoyl moiety linked to the dihydrolipoamide acetyltransferase component of the pyruvate dehydrogenase complex. E1 is an alpha (2)beta (2) tetramer (similar to 154 kDa). Crystals of this recombinant enzyme have been grown in polyethylene glycol 3350 using a vapor-diffusion method at 295 K. The crystals are characterized as orthorhombic, space group P2(1)2(1)2(1), with unit-cell parameters a = 64.2, b = 126.9, c = 190.2 Angstrom. Crystals diffracted to a minimum d spacing of 2.5 Angstrom. The asymmetric unit contains one alpha (2)beta (2) tetrameric E1 assembly; self-rotation function analysis showed a pseudo-twofold symmetry relating the two alpha beta dimers. C1 Univ Space Res Assoc, Huntsville, AL 35803 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. SUNY Buffalo, Dept Biochem, Sch Med & Biomed Sci, Buffalo, NY 14214 USA. Argonne Natl Lab, Struct Biol Ctr, Argonne, IL 60439 USA. RP Ciszak, E (reprint author), Univ Space Res Assoc, 4950 Corp Dr, Huntsville, AL 35803 USA. FU NIDDK NIH HHS [DK20478] NR 20 TC 2 Z9 5 U1 0 U2 2 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 MAR PY 2001 VL 57 BP 465 EP 468 DI 10.1107/S0907444901000427 PN 3 PG 4 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA 406TP UT WOS:000167231500024 PM 11223534 ER PT J AU Dyson, RW Goodrich, JW AF Dyson, RW Goodrich, JW TI Automated approach to very high-order aeroacoustic computations SO AIAA JOURNAL LA English DT Article ID SCHEMES; SIMULATION; ALGORITHMS AB Computational aeroacoustics requires efficient, high-resolution simulation tools. For smooth problems, this is best accomplished with very high-order in space and time methods on small stencils. However, the complexity of highly accurate numerical methods can inhibit their practical application, especially in irregular geometries, This complexity is reduced by using a special form of Hermite divided-difference spatial interpolation on Cartesian grids, and a Cauchy-Kowalewski recursion procedure for time advancement. In addition, ii stencil constraint tree reduces the complexity of interpolating grid points that are located near wall boundaries. These procedures are used to develop automatically and to implement very high-order methods (> 15) for solving the linearized Euler equations that can achieve less than one grid point per wavelength resolution away from boundaries by including spatial derivatives of the primitive variables at each grid point. The accuracy of stable surface treatments is currently limited to 11th order for grid aligned boundaries and to 2nd order for irregular boundaries. C1 NASA, Lewis Res Ctr, Acoust Branch, Struct & Acoust Div,Res & Technol Directorate, Cleveland, OH 44135 USA. RP Dyson, RW (reprint author), NASA, Lewis Res Ctr, Acoust Branch, Struct & Acoust Div,Res & Technol Directorate, Cleveland, OH 44135 USA. NR 42 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 2001 VL 39 IS 3 BP 396 EP 406 DI 10.2514/2.1349 PG 11 WC Engineering, Aerospace SC Engineering GA 409JQ UT WOS:000167380900005 ER PT J AU Akgun, MA Haftka, RT Wu, KC Walsh, JL Garcelon, JH AF Akgun, MA Haftka, RT Wu, KC Walsh, JL Garcelon, JH TI Efficient structural optimization for multiple load cases using adjoint sensitivities SO AIAA JOURNAL LA English DT Article AB Adjoint sensitivity calculation of stress, buckling, and displacement constraints may be much less expensive than direct sensitivity calculation when the number of load cases is large. In general, it is more difficult to implement the adjoint method than the direct method, but it is shown that the use of the continuum adjoint method, along with homogeneity conditions, can alleviate the problem. Expressions for von Mises stress and local buckling sensitivities For isotropic plate elements are derived. Computational efficiency of the adjoint method is sensitive to the number of constraints, and, therefore, the adjoint method benefits from constraint lumping. A continuum version of the Kreisselmeier-Steinhauser Functional is chosen to lump constraints. The adjoint and direct methods are compared for three examples: a truss structure, a small high-speed civil transport (HSCT) model, and a large HSCT model. These sensitivity derivatives are then used in optimization. C1 Middle E Tech Univ, Dept Aeronaut Engn, TR-06531 Ankara, Turkey. Univ Florida, Dept Aerosp Engn, Gainesville, FL 32611 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Vanderplaats Res & Dev Inc, Colorado Springs, CO 80906 USA. RP Akgun, MA (reprint author), Middle E Tech Univ, Dept Aeronaut Engn, TR-06531 Ankara, Turkey. NR 13 TC 17 Z9 17 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 2001 VL 39 IS 3 BP 511 EP 516 DI 10.2514/2.1336 PG 6 WC Engineering, Aerospace SC Engineering GA 409JQ UT WOS:000167380900021 ER PT J AU Ortiz, RM Wade, CE Ortiz, CL AF Ortiz, RM Wade, CE Ortiz, CL TI Effects of prolonged fasting on plasma cortisol and TH in postweaned northern elephant seal pups SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE fat metabolism; food deprivation; leptin; marine mammals ID SPERMOPHILUS-RICHARDSONI; GROUND-SQUIRRELS; BODY-WEIGHT; METABOLISM; THYROXINE; PROTEIN; BINDING; SERUM; GLUCOCORTICOIDS; LIPOLYSIS AB Northern elephant seal (Mirounga angustirostris) pups rely on the oxidation of fat stores as their primary source of energy during their 8- to 12-wk postweaning fast; however, potential endocrine mechanisms involved with this increased fat metabolism have yet to be examined. Therefore, 15 pups were serially blood sampled in the field during the first 7 wk of their postweaning fast to examine the changes in plasma concentrations of cortisol and thyroid hormones (TH), which are involved in fat metabolism in other mammals. Cortisol increased, indicating that it contributed to an increase in lipolysis. Increased total triiodothyronine ((TH) and thyroxine (tT(4)) may not reflect increased thyroid gland activity, but rather alterations in hormone metabolism. tT(3)-to-tT(4) ratio decreased, suggesting a decrease in thyroxine (T-4) deiodination, whereas the negative correlation between total proteins and free T-4 suggests that the increase in free hormone is attributed to a decrease in binding globulins. Changes in TH are most similar to those observed during hibernation than starvation in mammals, suggesting that the metabolic adaptations to natural fasting are more similar to hibernation despite the fact these animals remain active throughout the fasting period. C1 Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. NASA, Ames Res Ctr, Div Life Sci, Neuroendocrinol Lab, Moffett Field, CA 94035 USA. RP Ortiz, RM (reprint author), Univ Calif Santa Cruz, Dept Biol, Santa Cruz, CA 95064 USA. FU NIGMS NIH HHS [GM 58903-01] NR 34 TC 84 Z9 85 U1 1 U2 16 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 MAR PY 2001 VL 280 IS 3 BP R790 EP R795 PG 6 WC Physiology SC Physiology GA 401FQ UT WOS:000166917900024 PM 11171659 ER PT J AU Xirouchakis, D Lindsley, DH Andersen, DJ AF Xirouchakis, D Lindsley, DH Andersen, DJ TI Assemblages with titanite (CaTiOSiO4), Ca-Mg-Fe olivine and pyroxenes, Fe-Mg-Ti oxides, and quartz: Part I. Theory SO AMERICAN MINERALOGIST LA English DT Article ID CONSISTENT THERMODYNAMIC DATA; PRESSURE PHASE-TRANSITION; HIGH-TEMPERATURE; EQUILIBRIA; UNCERTAINTIES; MINERALS; ILMENITE; CATISIO5 AB Critical evaluation of the thermodynamic data for titanite, in conjunction with a heat capacity equation that takes into account the P2(1)/a <->A2/a transition and a more complete P-V-T data set for titanite, indicates that: (1) enthalpy of formation values greater than -2600 kJ/mol are not supported by calorimetry; (2) calculated internally consistent feasible solutions converge to enthalpy of formation from the elements values between -2608 and -2600 kJ/mol and 113 to 121 J/mol.K for the entropy; (3) the practice of adjusting the enthalpy of formation to fit phase equilibrium experiments may be erroneous, in contrast, it is the currently accepted entropy of 129.20 +/- 0.84 J/mol.K that may need revision to a smaller value. Consequently, we optimize standard-state properties for end-mem ber titanite (P2(1)/a structure) consistent with the thermodynamic data in the program QUILF. In addition, we use a modified version of the program to calibrate equilibria among titanite (CaTiOSiO4), Fe-Mg-Ti ilmenite and spinel, Ca-Mg-Fe pyroxenes and olivine, and quartz. Calculations at 1 and 3 kbar, and 650, 850, and 1100 degreesC, in the system CaO-MgO-FeO-Fe2O3-TiO2-SiO2, suggest that the reactions: augite + ilmenite = titanite + spinel phase + quartz and augite + ilmenite + quartz = titanite + orthopyroxene impose well defined fo(2), a(SiO2), and X-Fe(Opx) restrictions to the assemblages (1) titanite + spinel phase + quartz, (2) titanite + orthopyroxene, (3) augite + ilmenite, and consequently titanite stability. The absence of quartz (a(SiO2)< 1 with respect to Qz) favors the sub-assemblage Fe-Mg-Ti spinel + titanite over augite + ilmenite, and the latter over titanite + orthopyroxene. Nonetheless, in the absence of quartz, no titanite-bearing assemblage is stable relative to olivine + orthopyroxene + augite + ilmenite + Fe-Mg-Ti spinel. From the phase relations, we can also infer that in quartz-saturated rocks: (1) titanite can coexist with orthopyroxene only at low X-Fe(Opx) values, regardless of fo(2) conditions, whereas the assemblage titanite + orthopyroxene + spinel phase requires high fo(2), relative Mg-en richment (from high to moderate X-Fe(Opx)), and temperatures less than or equal to 650 degreesC. (2) The association of titanite with a spinel phase is generally indicative of relatively oxidizing conditions. (3) The assemblage titanite + olivine requires fo(2) condition close to FMQ and relative Fe-enrichment (from moderate to high X-Fe(Opx)), and temperatures less than or equal to 650 degreesC. C1 NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. SUNY Stony Brook, Dept Geosci, Stony Brook, NY 11794 USA. SUNY Stony Brook, Ctr High Pressure Res, Stony Brook, NY 11794 USA. ConnectSouth Inc, Austin, TX 78759 USA. RP Xirouchakis, D (reprint author), NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Mail Code SN2, Houston, TX 77058 USA. NR 34 TC 23 Z9 24 U1 0 U2 6 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 MAR PY 2001 VL 86 IS 3 BP 247 EP 253 PG 7 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 408TN UT WOS:000167343900006 ER PT J AU Xirouchakis, D Lindsley, DH Frost, BR AF Xirouchakis, D Lindsley, DH Frost, BR TI Assemblages with titanite (CaTiOSiO4), Ca-Mg-Fe olivine and pyroxenes, Fe-Mg-Ti oxides, and quartz: Part II. Application SO AMERICAN MINERALOGIST LA English DT Article ID FISH-CANYON TUFF; CRYSTAL-CHEMISTRY; MAGMATIC CONDITIONS; ALUMINOUS TITANITE; UNGAVA OROGEN; EQUILIBRIA; COLORADO; CONSTRAINTS; STABILITY; MAGNETITE AB In the system CaO-MgO-FeO-Fe2O3-TiO2-SiO2, equilibria among titanite, pyroxene(s), olivine, spinel phase, ilmenite, and quartz constrain fo(2), T, a(SiO2), a(TiO2), a(Fe), and the compositional variables. mu TiFe2+Fe-23+, mu Ca(Mg,Fe)(-1), and consequently mu Mg,Fe-1 among the silicate and oxide phases. These equilibria can provide the framework for a better understanding of relevant titanite-bearing natural assemblages. In addition, such equilibria can constrain the variables that operate during crystallization of igneous and metamorphic rocks. Titanite-bearing assemblages with pyroxene(s), Fe-Mg-Ti ilmenite and spinel, olivine, and quartz are rare in metamorphic rocks but are common in igneous rocks where they are more commonly reported in plutonic than in volcanic rocks. Probably because, at high temperatures, titanite cannot coexist with the relative common in volcanic rocks sub-assemblage augite + orthopyroxene + olivine + spinel phase + ilmenite. Moreover, decreasing pressure and temperature conditions appear to favor titanite. Thus, it is not surprising that titanite is commonly observed in slowly cooled rocks, albeit, most typically in association with amphibole. We argue that the titanite + amphibole association is favored by high a(H2O) and, because a(H2O) typically increases during crystallization of a pluton, titanite + amphibole (and consequently titanite) is more common in plutonic than in volcanic rocks. We have used a modified version of the program QUILF that includes our thermodynamic data for titanite and appropriate titanite-bearing assemblages to estimate the equilibrium crystallization conditions of samples from: (1) a tonalite from the Myoken-Zan granitic complex in Japan; (2) the Sandwich Horizon in the Skaergaard intrusion in Greenland; (3) rhyodacites, dacites, and andesites from the Sajama, Porquesa, and Parinacota volcanoes in the Andes; (4) the Fish Canyon Tuff in Colorado; and (5) a quartz-rich, calc-silicate gneiss adjacent to the Horse Creek Anorthosite Complex in Wyoming. The calculations suggest that: (1) these titanite-bearing assemblages crystallized at values of fo(2), that ranged from slightly below FMQ to more than 3 logfo(2) units above FMQ at 500-800 degreesC; and (2) the stability of titanite is controlled by T, fo(2), a(SiO2), and the compositions of the coexisting oxides and silicates. C1 NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. SUNY Stony Brook, Dept Geosci, Stony Brook, NY 11794 USA. SUNY Stony Brook, Ctr High Pressure Res, Stony Brook, NY 11794 USA. Univ Wyoming, Dept Geol & Geophys, Laramie, WY 82071 USA. RP Xirouchakis, D (reprint author), NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Mail Code SN2, Houston, TX 77058 USA. EM dxirouch@ems.jsc.nasa.gov NR 42 TC 29 Z9 30 U1 4 U2 10 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 MAR PY 2001 VL 86 IS 3 BP 254 EP 264 PG 11 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 408TN UT WOS:000167343900007 ER PT J AU Golden, DC Ming, DW Schwandt, CS Lauer, HV Socki, RA Morris, RV Lofgren, GE McKay, GA AF Golden, DC Ming, DW Schwandt, CS Lauer, HV Socki, RA Morris, RV Lofgren, GE McKay, GA TI A simple inorganic process for formation of carbonates, magnetite, and sulfides in Martian meteorite ALH84001 SO AMERICAN MINERALOGIST LA English DT Article ID LOW-TEMPERATURE; PETROLOGIC EVIDENCE; ORIGIN; ALLAN-HILLS-84001; HISTORY; MARS; AGE AB We show experimental evidence that the zoned Mg-Fe-Ca carbonates, magnetite, and Fe sulfides in Martian meteorite ALH84001 may have formed by simple, inorganic processes. Chemically zoned carbonate globules and Fe sulfides were rapidly precipitated under low-temperature (150 degreesC), hydrothermal, and non-equilibrium conditions from multiple fluxes of Ca-Mg-Fe-CO2-S-H2O solutions that have different compositions. Chemically pure, single-domain, defect-free magnetite crystals were formed by subsequent decomposition of previously precipitated Fe-rich carbonates by brief heating to 470 degreesC. The sequence of hydrothermal precipitation of carbonates from flowing CO2-rich waters followed by a transient thermal event provides an inorganic explanation for the formation of the carbonate globules, magnetite, and Fe sulfides in ALH84001. In separate experiments, kinetically controlled C-13 enrichment was observed in synthetic carbonates that is similar in magnitude to the C-13 enrichment in ALH84001 carbonates. C1 NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. Hernandez Engn Inc, Houston, TX 77062 USA. Lockheed Martin, Houston, TX 77258 USA. RP Golden, DC (reprint author), NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Mail Code SN2, Houston, TX 77058 USA. NR 29 TC 87 Z9 91 U1 1 U2 13 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 MAR PY 2001 VL 86 IS 3 BP 370 EP 375 PG 6 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA 408TN UT WOS:000167343900021 ER PT J AU Sargsyan, AE Hamilton, DR Nicolaou, S Kirkpatrick, AW Campbell, MR Billica, RD Dawson, D Williams, DR Melton, SL Beck, G Forkheim, K Dulchavsky, SA AF Sargsyan, AE Hamilton, DR Nicolaou, S Kirkpatrick, AW Campbell, MR Billica, RD Dawson, D Williams, DR Melton, SL Beck, G Forkheim, K Dulchavsky, SA TI Ultrasound evaluation of the magnitude of pneumothorax: A new concept SO AMERICAN SURGEON LA English DT Article; Proceedings Paper CT 43rd Annual Meeting of the Midwest-Surgical-Association CY AUG 13-16, 2000 CL MACKINAC ISL, MICHIGAN SP Midwest Surg Assoc ID DIAGNOSIS AB Pneumothorax is commonly seen in trauma patients; the diagnosis is confirmed by radiography. The use of ultrasound where radiographic capabilities are absent, is being investigated by the National Aeronautics and Space Administration. We investigated the ability of ultrasound to assess the magnitude of pneumothorax in a porcine model. Sonography was performed on anesthetized pigs in both ground-based laboratory (n = 5) and microgravity conditions (0 x g) aboard the KC-135 aircraft during parabolic flight (n = 4). Aliquots of air (50-100 cm(3)) were introduced into the chest to simulate pneumothorax. Results were videorecorded and digitized for later interpretation. Several distinct sonographic patterns of partial lung sliding were noted including the combination of a sliding zone with a still zone and a "segmented" sliding zone. These "partial lung sliding" patterns exclude massive pneumothorax manifested by a complete separation of the lung from the parietal pleura. In 0 x g, the sonographic picture is more diverse; one x g differences between posterior and anterior aspects are diminished. Modest pneumothorax can be inferred by the ultrasound sign of "partial lung sliding." This finding, which increases the negative predictive value of thoracic ultrasound, may be attributed to intermittent pleural contact, small air spaces, or alterations in pleural lubricant. Further studies of these phenomena are warranted. C1 Wyle Labs, Houston, TX USA. Vancouver Gen Hosp, Vancouver, BC, Canada. NASA, Space & Life Sci Directorate, Lyndon B Johnson Space Ctr, Houston, TX USA. Wayne State Univ, Sch Med, Detroit, MI USA. RP Dulchavsky, SA (reprint author), Detroit Receiving Hosp, Dept Surg, 4201 St Antoine, Detroit, MI 48201 USA. NR 9 TC 39 Z9 41 U1 0 U2 0 PU SOUTHEASTERN SURGICAL CONGRESS PI ATLANTA PA 141 WEST WIEUCA RD, STE B100, ATLANTA, GA 30342 USA SN 0003-1348 J9 AM SURGEON JI Am. Surg. PD MAR PY 2001 VL 67 IS 3 BP 232 EP 235 PG 4 WC Surgery SC Surgery GA 409UE UT WOS:000167403400010 PM 11270880 ER PT J AU Larruquert, JI Keski-Kuha, RAM AF Larruquert, JI Keski-Kuha, RAM TI Multilayer coatings for narrow-band imaging in the extreme ultraviolet SO APPLIED OPTICS LA English DT Article ID OPTICAL-CONSTANTS; REFLECTANCE MEASUREMENTS; THIN-FILMS AB Multilayer coatings for the extreme ultraviolet with high reflectance at a spectral band of interest and zero reflectance at another band to be suppressed have been designed and prepared. Multilayer coatings were designed to maximize normal-incidence reflectance at the O+ 83.4-nm spectral line and to suppress at the same time radiation at the 121.6-nm hydrogen Lyman alpha line. Fresh Al/MgF2/Mo multilayer coatings resulted in high reflection/suppression ratios at the above wavelengths. The coatings also exhibited a dip in reflectance at 102.6-nm Lyman beta. The coatings showed some slow but steady degradation over time that could be partially eliminated by sample cleaning. Al/MgF2/Mo multilayer coatings protected with a thin ion-beam-deposited C film were found to give a high reflection/suppression ratio with lower degradation over time. (C) 2001 Optical Society of America C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM larruquert@io.csic.es OI Larruquert, Juan/0000-0001-6356-9702 NR 10 TC 10 Z9 10 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAR 1 PY 2001 VL 40 IS 7 BP 1126 EP 1131 DI 10.1364/AO.40.001126 PG 6 WC Optics SC Optics GA 404QV UT WOS:000167112900014 PM 18357097 ER PT J AU Nguyen, QV Paul, PH AF Nguyen, QV Paul, PH TI Photochemical effects of KrF excimer excitation in laser-induced fluorescence measurements of OH in combustion environments SO APPLIED PHYSICS B-LASERS AND OPTICS LA English DT Article ID ROTATIONAL ENERGY-TRANSFER; ATMOSPHERIC-PRESSURE FLAMES; INDUCED PREDISSOCIATIVE FLUORESCENCE; TEMPERATURE-MEASUREMENTS; MULTIPHOTON IONIZATION; DIAGNOSTICS; DYNAMICS; MODEL; H2O; D2O AB This paper presents experimental evidence that using the KrF excimer laser fur quantitative laser-induced fluorescence (LIF) studies of the OH A-X (3,0) system is highly problematic if the effects of both photobleaching and photochemistry are not included for laser spectral irradiances greater than 20 MW/cm(2)cm(-1). Pump-probe and time-resolved measurements of the OH LTF signal in an atmospheric pressure, premixed CH4-air flame at low- and high-laser-spectral-irradiance conditions show that a. significant amount of OH is produced from photofragments resulting from the simultaneous 2-photon predissociation of H2O molecules in the (C) over tilde-(X) over tilde system. A 5+2-level rate-equation model that includes the effects of both photobleaching and photochemical OH production is shown to satisfactorily pre diet the data using a single adjustable parameter given by the effective, spectrally integrated 2-photon cross-section of H2O near 248 nm. The time-integrated OH LIF signal was found to depend on both the laser spectral irradiance and the local concentration of H2O. Additionally, use of the KrF excimer laser for 2-line rotational thermometry can produce temperature errors as great as +550 K at high laser-pulse energies. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Eksigent Technol, LLC, Livermore, CA 94550 USA. RP Nguyen, QV (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 31 TC 1 Z9 1 U1 0 U2 2 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0946-2171 J9 APPL PHYS B-LASERS O JI Appl. Phys. B-Lasers Opt. PD MAR PY 2001 VL 72 IS 4 BP 497 EP 505 PG 9 WC Optics; Physics, Applied SC Optics; Physics GA 416RZ UT WOS:000167795100016 ER PT J AU Morrison, D AF Morrison, David TI The NASA Astrobiology Program SO ASTROBIOLOGY LA English DT Article DE Astrobiology; NASA; Roadmap; Policy; Research program AB The new discipline of astrobiology addresses fundamental questions about life in the universe: "Where did we come from?" "Are we alone in the universe?" "What is our future beyond the Earth?" Developing capabilities in biotechnology, informatics, and space exploration provide new tools to address these old questions. The U.S. National Aeronautics and Space Administration (NASA) has encouraged this new discipline by organizing workshops and technical meetings, establishing a NASA Astrobiology Institute, providing research funds to individual investigators, ensuring that astrobiology goals are incorporated in NASA flight missions, and initiating a program of public outreach and education. Much of the initial effort by NASA and the research community was focused on determining the technical content of astrobiology. This paper discusses the initial answer to the question "What is astrobiology?" as described in the NASA Astrobiology Roadmap. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Morrison, D (reprint author), NASA, Ames Res Ctr, MS 200-7, Moffett Field, CA 94035 USA. EM dmorrison@arc.nasa.gov NR 22 TC 29 Z9 30 U1 0 U2 7 PU MARY ANN LIEBERT, INC PI NEW ROCHELLE PA 140 HUGUENOT STREET, 3RD FL, NEW ROCHELLE, NY 10801 USA SN 1531-1074 EI 1557-8070 J9 ASTROBIOLOGY JI Astrobiology PD MAR PY 2001 VL 1 IS 1 BP 3 EP 13 DI 10.1089/153110701750137378 PG 11 WC Astronomy & Astrophysics; Biology; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Life Sciences & Biomedicine - Other Topics; Geology GA V38SK UT WOS:000209362900002 PM 12448992 ER PT J AU Conrad, PG Nealson, KH AF Conrad, Pamela G. Nealson, Kenneth H. TI A Non-Earthcentric Approach to Life Detection SO ASTROBIOLOGY LA English DT Article DE Life detection; Biosignatures; Chemical fossils; Astrobiology AB The ultimate goal of a comprehensive life detection strategy is never to miss life when we encounter it. To accomplish this goal, we must define life in universal, that is, non-Earth-centric, measurable terms. Next, we must understand the nature of biosignatures observed from the measured parameters of life. And finally, we must have a clear idea of the end-member states for the search-what does life, past life, or no life look like (in terms of the measured parameters) at multiple spatial and temporal scales? If we can approach these problems both in the laboratory and in the field on Earth, then we have a chance of being able to detect life elsewhere in our solar system. What are the required limits of detection at each of those scales? What spatial, spectral, and temporal resolutions are necessary to detect life? These questions are actively being investigated in our group, and in this report, we present our strategy and approach to non-Earthcentric life detection. C1 [Conrad, Pamela G.; Nealson, Kenneth H.] CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Conrad, PG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 183-301, Pasadena, CA 91109 USA. EM conrad@jpl.nasa.gov FU National Aeronautics and Space Administration; National Astrobiology Institute, NASA; U.S. Department of Energy (NABIR) FX The work described was performed at the Jet Propulsion Laboratory, California Institute of Technology under contract with the National Aeronautics and Space Administration. This work was supported, in part, by the National Astrobiology Institute, NASA, and the U.S. Department of Energy (NABIR). NR 29 TC 35 Z9 35 U1 1 U2 6 PU MARY ANN LIEBERT, INC PI NEW ROCHELLE PA 140 HUGUENOT STREET, 3RD FL, NEW ROCHELLE, NY 10801 USA SN 1531-1074 EI 1557-8070 J9 ASTROBIOLOGY JI Astrobiology PD MAR PY 2001 VL 1 IS 1 BP 15 EP 24 DI 10.1089/153110701750137396 PG 10 WC Astronomy & Astrophysics; Biology; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Life Sciences & Biomedicine - Other Topics; Geology GA V38SK UT WOS:000209362900003 PM 12448993 ER PT J AU McKay, CP Marinova, MM AF McKay, Christopher P. Marinova, Margarita M. TI The Physics, Biology, and Environmental Ethics of Making Mars Habitable SO ASTROBIOLOGY LA English DT Article DE Mars; Terraforming; Planetary ecosynthesis; Greenhouse warming; Environmental ethics AB The considerable evidence that Mars once had a wetter, more clement, environment motivates the search for past or present life on that planet. This evidence also suggests the possibility of restoring habitable conditions on Mars. While the total amounts of the key molecules-carbon dioxide, water, and nitrogen-needed for creating a biosphere on Mars are unknown, estimates suggest that there may be enough in the subsurface. Super greenhouse gases, in particular, perfluorocarbons, are currently the most effective and practical way to warm Mars and thicken its atmosphere so that liquid water is stable on the surface. This process could take similar to 100 years. If enough carbon dioxide is frozen in the South Polar Cap and absorbed in the regolith, the resulting thick and warm carbon dioxide atmosphere could support many types of microorganisms, plants, and invertebrates. If a planet-wide martian biosphere converted carbon dioxide into oxygen with an average efficiency equal to that for Earth's biosphere, it would take >100,000 years to create Earth-like oxygen levels. Ethical issues associated with bringing life to Mars center on the possibility of indigenous martian life and the relative value of a planet with or without a global biosphere. C1 [McKay, Christopher P.; Marinova, Margarita M.] NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. [Marinova, Margarita M.] MIT, Cambridge, MA 02139 USA. RP McKay, CP (reprint author), NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. EM cmckay@arc.nasa.gov NR 109 TC 17 Z9 19 U1 12 U2 52 PU MARY ANN LIEBERT, INC PI NEW ROCHELLE PA 140 HUGUENOT STREET, 3RD FL, NEW ROCHELLE, NY 10801 USA SN 1531-1074 EI 1557-8070 J9 ASTROBIOLOGY JI Astrobiology PD MAR PY 2001 VL 1 IS 1 BP 89 EP 109 DI 10.1089/153110701750137477 PG 21 WC Astronomy & Astrophysics; Biology; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Life Sciences & Biomedicine - Other Topics; Geology GA V38SK UT WOS:000209362900007 PM 12448997 ER PT J AU Allen, CC Westall, F Schelble, RT AF Allen, Carlton C. Westall, Frances Schelble, Rachel T. TI Importance of a Martian Hematite Site for Astrobiology SO ASTROBIOLOGY LA English DT Article DE Mars; Hematite; Microfossils; Banded iron formation; Astrobiology AB Defining locations where conditions may have been favorable for life is a key objective for the exploration of Mars. Of prime importance are sites where conditions may have been favorable for the preservation of evidence of prebiotic or biotic processes. Areas displaying significant concentrations of the mineral hematite (alpha-Fe2O3), recently identified by thermal emission spectrometry, may have significance in the search for evidence of extraterrestrial life. Since iron oxides can form as aqueous mineral precipitates, the potential exists to preserve microscopic evidence of life in iron oxide-depositing ecosystems. Terrestrial hematite deposits proposed as possible analogs for hematite deposits on Mars include massive (banded) iron formations, iron oxide hydrothermal deposits, iron-rich laterites and ferricrete soils, and rock varnish. We report the potential for long-term preservation of microfossils by iron oxide mineralization in specimens of the similar to 2,100-Ma banded iron deposit of the Gunflint Formation, Canada. Scanning and analytical electron microscopy reveals micrometer-scale rods, spheres, and filaments consisting predominantly of iron and oxygen with minor carbon. We interpret these objects as microbial cells permineralized by an iron oxide, presumably hematite. The confirmation of ancient martian microbial life in hematite deposits will require the return of samples to terrestrial laboratories. A hematite-rich deposit composed of aqueous iron oxide precipitates may thus prove to be a prime site for future sample return. C1 [Allen, Carlton C.] NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. [Westall, Frances] Lunar & Planetary Inst, Houston, TX 77058 USA. [Schelble, Rachel T.] Univ New Mexico, Dept Earth & Planetary Sci, Albuquerque, NM 87131 USA. RP Allen, CC (reprint author), NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. EM carlton.c.allen1@jsc.nasa.gov FU NASA Astrobiology Institute; Lunar and Planetary Institute Summer Intern Program FX The authors acknowledge support from the NASA Astrobiology Institute and the Lunar and Planetary Institute Summer Intern Program. Everett Gibson generously provided samples from the Gunflint Formation for analysis, and Craig Schwandt and Susan Wentworth gave invaluable support on the SEM. Discussions with Jaclyn Allen, Henry Chafetz, Jack Farmer, Douglas Ming, and Richard Morris, as well as thoughtful reviews by Sherry Cady, Beda Hofmann, and Alex Ruzicka, substantially improved the manuscript. NR 75 TC 23 Z9 23 U1 0 U2 4 PU MARY ANN LIEBERT, INC PI NEW ROCHELLE PA 140 HUGUENOT STREET, 3RD FL, NEW ROCHELLE, NY 10801 USA SN 1531-1074 EI 1557-8070 J9 ASTROBIOLOGY JI Astrobiology PD MAR PY 2001 VL 1 IS 1 BP 111 EP 123 DI 10.1089/153110701750137495 PG 13 WC Astronomy & Astrophysics; Biology; Geosciences, Multidisciplinary SC Astronomy & Astrophysics; Life Sciences & Biomedicine - Other Topics; Geology GA V38SK UT WOS:000209362900008 PM 12448998 ER PT J AU Waller, WH Fanelli, MN Keel, WC Bohlin, R Collins, NR Madore, BF Marcum, PM Neff, SG O'Connell, RW Offenberg, JD Roberts, MS Smith, AM Stecher, TP AF Waller, WH Fanelli, MN Keel, WC Bohlin, R Collins, NR Madore, BF Marcum, PM Neff, SG O'Connell, RW Offenberg, JD Roberts, MS Smith, AM Stecher, TP TI Ultraviolet signposts of resonant dynamics in the starburst-ringed Sab galaxy M94 (NGC 4736) SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : evolution; galaxies : individual (M94, NGC 4736); galaxies : kinematics and dynamics; galaxies : photometry; galaxies : spiral; ultraviolet emission ID H-II REGIONS; NGC 4736; IMAGING TELESCOPE; STAR-FORMATION; SPIRAL GALAXIES; NUCLEAR REGIONS; NEARBY GALAXIES; GALACTIC NUCLEI; EXPANDING RING; VELOCITY-FIELD AB The dynamic orchestration of star-birth activity in the starburst-ringed galaxy M94 (NGC 4736) is investigated using images from the Ultraviolet Imaging Telescope (UIT; far-ultraviolet [FUV] band), Hubble Space Telescope (HST; near-ultraviolet [NUV] band), Kitt Peak 0.9 m telescope (H alpha, R, and I bands), and Palomar 5 m telescope (B band), along with spectra from the International Ultraviolet Explorer (IUE) and the Lick 1 m telescope. The wide-field UIT image shows FUV emission from (1) an elongated nucleus, (2) a diffuse inner disk, where H alpha is observed in absorption, (3) a bright inner ring of H II regions at the perimeter of the inner disk (R = 48 " = 1.1 kpc), and (4) two 500 pc size knots of hot stars exterior to the ring on diametrically opposite sides of the nucleus (R = 130 " = 2.9 kpc). The HST Faint Object Camera image resolves the NUV emission from the nuclear region into a bright core and a faint 20 " long "minibar" at a position angle of 30 degrees. Optical and IUE spectroscopy of the nucleus and diffuse inner disk indicates a similar to 10(7)-10(8) yr old stellar population from low-level star-birth activity blended with some LINER activity. Analysis of the H alpha-, FUV-, NUV-, B-, R-, and I-band emissions, along with other observed tracers of stars and gas in M94, indicates that most of the star formation is being orchestrated via ring-bar dynamics, involving the nuclear minibar, inner ring, oval disk, and outer ring. The inner starburst ring and bisymmetric knots at intermediate radius, in particular, argue for bar-mediated resonances as the primary drivers of evolution in M94 at the present epoch. Similar processes may be governing the evolution of the "core-dominated" galaxies that have been observed at high red-shift. The gravitationally lensed "Pretzel Galaxy" (0024+1654) at a redshift of similar to1.5 provides an important precedent in this regard. C1 Tufts Univ, Dept Phys & Astron, Medford, MA 02155 USA. NASA, Goddard Space Flight Ctr, ITSS Corp, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Univ N Texas, Dept Phys, Denton, TX 76203 USA. Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Texas Christian Univ, Dept Phys, Ft Worth, TX 76129 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. RP Waller, WH (reprint author), Tufts Univ, Dept Phys & Astron, Medford, MA 02155 USA. NR 80 TC 14 Z9 14 U1 1 U2 2 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 MAR PY 2001 VL 121 IS 3 BP 1395 EP 1412 DI 10.1086/319384 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 412YL UT WOS:000167582800014 ER PT J AU Keel, WC White, RE AF Keel, WC White, RE TI Seeing galaxies through thick and thin. III. Hubble Space Telescope imaging of the dust in backlit spiral galaxies SO ASTRONOMICAL JOURNAL LA English DT Article DE dust, extinction; galaxies : ISM; galaxies : spiral ID H-I; NGC-1275; CLUSTER AB We present analysis of Wide Field Planetary Camera 2 imaging of two spiral galaxies partially backlit by elliptical or S0 systems in the pairs AM 1316-241 and AM 0500-620, as well as the (probably spiral) foreground system in NGC 1275. Images in B and I are used to determine the reddening curve of dust in these systems. The foreground spiral component of AM 1316-241 shows dust strongly concentrated in discrete arms, with a reddening law very close to the Milky Way mean [R = A(V)/E(B - V) = 3.4 +/- 0.2]. The dust distribution is scale-free between about 100 pc and the arm dimension, about 8 kpc. The foreground spiral in AM 0500-620 shows dust concentrated in arms and interarm spurs, with measurable interarm extinction as well. In this case, although the dust properties are less well-determined than in AM 1316-241, we find evidence for a steeper extinction law than the Milky Way mean (formally, R approximate to 2.5 +/- 0.4, with substantial variation depending on data quality in each region). The shape of the reddening law suggests that at least in AM 1316-241 we have resolved most of the dust structure. In AM 0500-620 it is less clear that we have resolved most of the dust structure, since the errors are larger. In AM 0500-620, the slope of the perimeter-scale relation (associated with fractal analysis) steepens systematically when going from regions of low to high extinction. A perimeter-smoothing length test for scale-free (fractal) behavior in AM 1316-241 shows a logarithmic slope typically -0.4 on 100-1000 pc scales. However, we cannot determine a unique fractal dimension from the defining area-perimeter relation, so the projected dust distribution is best defined as fractal-like. For scales above 2-4 pixels (120-250 pc), the box-counting estimate yields a fractal dimension close to 1.4, but the perimeter-area relation yields a dimension of 0.7 on large scales and inconsistent results for small scales, so that the distribution shows only some aspects of a fractal nature. In neither galaxy do we see significant regions, even on single-pixel scales in spiral arms, with The measurements in NGC 1275 are A(B) > 2.5. compromised by our lack of independent knowledge of the foreground system's light distribution, but masked sampling of the absorption suggests an effective reddening curve much flatter than the Milky Way mean (but this may indicate that the foreground system has been affected by immersion in the hot intracluster gas or is inside the stellar distribution of NGC 1275). The bright blue star clusters trace the absorption in this system quite closely, indicating that these clusters belong to the foreground system and not to NGC 1275 itself. C1 Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Keel, WC (reprint author), Univ Alabama, Dept Phys & Astron, Tuscaloosa, AL 35487 USA. NR 28 TC 42 Z9 42 U1 0 U2 1 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 MAR PY 2001 VL 121 IS 3 BP 1442 EP 1455 DI 10.1086/319386 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 412YL UT WOS:000167582800017 ER PT J AU Boker, T van der Marel, RP Mazzuca, L Rix, HW Rudnick, G Ho, LC Shields, JC AF Boker, T van der Marel, RP Mazzuca, L Rix, HW Rudnick, G Ho, LC Shields, JC TI A young stellar cluster in the nucleus of NGC 4449 SO ASTRONOMICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 4449); galaxies : nuclei; galaxies : starburst ID IRREGULAR GALAXY NGC-4449; STAR-FORMATION; SYNTHESIS MODELS; NEARBY GALAXIES; SPIRAL GALAXIES; DISK GALAXIES; LINE SPECTRA; EMISSION; EVOLUTION; REGIONS AB We have obtained 1-2 Angstrom resolution optical echellette spectra of the nuclear star cluster in the nearby starburst galaxy NGC 4449. The light is clearly dominated by a very young (6-10 Myr) population of stars. For our age dating, we have used recent population synthesis models to interpret the observed equivalent width of stellar absorption features such as the H I Balmer series and the Ca II triplet around 8500 Angstrom. We also compare the observed spectrum of the nuclear cluster with synthesized spectra for stellar populations of varying ages. All these approaches yield a consistent cluster age. Metallicity estimates based on the relative intensities of various ionization lines yield no evidence for significant enrichment in the center of this low-mass galaxy: the metallicity of the nuclear cluster is about one-fourth of the solar value, in agreement with independent estimates for the disk material of NGC 4449. C1 European Space Agcy, Div Astrophys, Space Telescope Sci Inst, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Max Planck Inst Astron, D-69117 Heidelberg, Germany. Observ Carnegie Inst Washington, Pasadena, CA 91101 USA. Ohio Univ, Dept Phys & Astron, Clippinger Res Labs, Athens, OH 45701 USA. RP Boker, T (reprint author), European Space Agcy, Div Astrophys, Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. NR 49 TC 39 Z9 39 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAR PY 2001 VL 121 IS 3 BP 1473 EP 1481 DI 10.1086/319415 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 412YL UT WOS:000167582800020 ER PT J AU Davidson, K Smith, N Gull, TR Ishibashi, K Hillier, DJ AF Davidson, K Smith, N Gull, TR Ishibashi, K Hillier, DJ TI The shape and orientation of the Homunculus Nebula based on spectroscopic velocities SO ASTRONOMICAL JOURNAL LA English DT Article DE circumstellar matter; ISM : individual (Homunculus Nebula); ISM : jets and outflows; stars : individual (eta Carinae); stars : mass loss; stars : winds, outflows ID ETA-CARINAE; MU-M; EJECTA; OUTBURSTS; VARIABLES; MOTION AB Doppler velocities give information about the three-dimensional shape and orientation of the bipolar ejecta of eta Car. We report slit spectroscopy obtained using the Space Telescope Imaging Spectrograph (HST/STIS), with spatial resolution adequate for good models. These data allow an independent estimate of the distance to this object. Equatorial velocities, not clearly recognized in earlier work, provide the first definite measure of the bipolar inclination angle relative to our line of sight. Equatorial structure is arguably the most significant new spectroscopic result reported here, and some of the equatorial gas has higher and lower velocities which probably represent later and earlier ejection events. A range of bipolar lobe shapes fit the data reasonably well; the worst ambiguities result from the nature of the object more than from instrumental limitations. C1 Univ Minnesota, Dept Astron, Minneapolis, MN 55455 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Pittsburgh, Dept Phys & Astron, Pittsburgh, PA 15260 USA. RP Davidson, K (reprint author), Univ Minnesota, Dept Astron, 116 Church St SE, Minneapolis, MN 55455 USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 26 TC 97 Z9 97 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAR PY 2001 VL 121 IS 3 BP 1569 EP 1577 DI 10.1086/319419 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 412YL UT WOS:000167582800029 ER PT J AU Hummel, CA Carquillat, JM Ginestet, N Griffin, RF Boden, AF Hajian, AR Mozurkewich, D Nordgren, TE AF Hummel, CA Carquillat, JM Ginestet, N Griffin, RF Boden, AF Hajian, AR Mozurkewich, D Nordgren, TE TI Orbital and stellar parameters of Omicron Leonis from spectroscopy and interferometry SO ASTRONOMICAL JOURNAL LA English DT Article DE binaries : spectroscopic; binaries : visual; stars : fundamental parameters; stars : individual (o Leonis); techniques : interferometric ID PROTOTYPE OPTICAL INTERFEROMETER; RADIAL-VELOCITY SPECTROMETER; EFFECTIVE TEMPERATURES; BOLOMETRIC CORRECTIONS; COMPOSITE SPECTRA; VISUAL ORBIT; BINARY STARS; TRANSFORMATIONS; ADJUSTMENT; DIAGRAMS AB We present a three-dimensional solution for the orbit of the double star Omicron Leonis, based on new photoelectric radial velocity data mainly from the Observatoire de Haute-Provence and on interferometric data obtained with the Navy Prototype Optical Interferometer, the Mark III Stellar Interferometer, and the Palomar Testbed Interferometer. Omicron Leo's primary is a giant of type F9 and the secondary is an A5m dwarf, for which we derive masses of 2.12 +/- 0.01 M. and 1.87 +/- 0.01 M ., respectively. The distance to the binary is determined to be 41.4 +/- 0.1 pc. Combining the distance with the measured apparent magnitudes and color differences between the components yields luminosities of 39.4 +/- 2.4 L. and 15.4 +/- 1.0 L. for primary and secondary, respectively. Data from the Palomar Testbed Interferometer taken at 2.2 mum are used to constrain the photometry in the infrared. C1 USN Observ, Astrometry Dept, Washington, DC 20392 USA. Observ Midi Pyrenees, Astrophys Lab, F-31400 Toulouse, France. Univ Cambridge, The Observatories, Cambridge CB3 0HA, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. USN, Remote Sensing Div, Res Lab, Washington, DC 20375 USA. USN Observ, NPOI, Flagstaff, AZ 86002 USA. RP Hummel, CA (reprint author), USN Observ, Astrometry Dept, 3450 Massachusetts Ave NW, Washington, DC 20392 USA. NR 59 TC 44 Z9 44 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAR PY 2001 VL 121 IS 3 BP 1623 EP 1635 DI 10.1086/319391 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 412YL UT WOS:000167582800035 ER PT J AU Rebull, LM AF Rebull, LM TI Rotation of young low-mass stars in the Orion Nebula cluster flanking fields SO ASTRONOMICAL JOURNAL LA English DT Article DE stars : pre-main-sequence; stars : rotation ID ALPHA-PERSEI CLUSTER; T-TAURI STARS; PROPER MOTIONS; TIME-SERIES; K-DWARFS; PERIODS; VARIABILITY; ACCRETION; PLEIADES; MEMBERS AB We have photometrically monitored similar to 3600 young, low-mass stars in four 45'x45' fields in the outer Orion Nebula cluster, surrounding but not including the Trapezium region. The 281 periodic variables we find do not produce the expected bimodal distribution of rotation periods. There is no unambiguous correlation of period with I-C - I-S, H - K-S, and U-V color excesses or more indirect disk indicators; the slowest rotators are not necessarily the disk candidates, and the disk candidates are not necessarily the slow rotators, regardless of how one defines a disk candidate. To the extent that the small numbers allow, the disk candidates represent a constant fraction of the total sample to P = 15 days, beyond which there are no disk candidates, inconsistent with the hypothesis that the more slowly rotating stars are more likely to have disks. We find an intriguing relationship between specific angular momentum (j) and some excesses, namely, H - K-s excesses and the strongest U-V excesses; whereas stars are found with j values ranging over similar to 10(6)-10(8) km(2) s(-1), disk candidates with these excesses are restricted to 10(6.5) km(2) s(-1) 2.3.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 406RG UT WOS:000167228500002 ER PT J AU Atlas, D AF Atlas, D TI Fallstreaks and their parent generators SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Editorial Material ID CIRRIFORM CLOUDS; ICE PHASE; EVOLUTION; CELLS; GROWTH AB We present a comparatively rare photograph of cirrus uncinus (mare's tail cirrus) fallstreaks with supercooled cumuliform generating heads. The image demonstrates regeneration of the clouds to account for the extended lifetime of both the generating cells and the ice crystal trails. The observations provide further support for prior hypotheses. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Atlas, D (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD MAR PY 2001 VL 82 IS 3 BP 477 EP 480 DI 10.1175/1520-0477(2001)082<0477:CAAFAT>2.3.CO;2 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 406RG UT WOS:000167228500005 ER PT J AU Harstad, K Bellan, J AF Harstad, K Bellan, J TI The D-2 variation for isolated LOX drops and polydisperse clusters in hydrogen at high temperature and pressures SO COMBUSTION AND FLAME LA English DT Article ID ROCKET CHAMBER PRESSURES; FLUID HYDROGEN; VAPORIZATION; ENVIRONMENTS; BEHAVIOR; COMBUSTION; DROPLETS AB A study of the d(2) variation for isolated fluid drops and for fluid drops belonging to polydisperse clusters has been conducted at a high temperature and elevated pressures. The mathematical formulation is based on a previously validated model of subcritical/supercritical isolated fluid drop behavior. Coupled with the isolated drop equations, a set of conservation equations has been developed to describe the global cluster behavior. All these equations are based on the general transport matrix including Sorer and Dufour terms and they are consistent with nonequilibrium thermodynamics and at low pressure with kinetic theory. Moreover, the model also accounts for real gas effects through accurate equations of state and for correct values of the transport properties in the high pressure, high temperature regime. The model has been first exercised for isolated LOX drops in H-2 at pressures ranging from 1.5 MPa (subcritical pressure for O-2) to 20 MPa (supercritical pressure for O-2). The results show that while at subcritical pressures the d(2) variation is nearly linear, with increasing pressure it departs considerably from the linear behavior; the largest departure occurs in the vicinity of the oxygen critical point. The slope of d(2)(t) was fitted using both a constant and a linear fit, and it was shown that the linear fit provides a better alternative for correlation purposes. Simulations were also conducted for clusters of LOX drops in H-2 in the range 6 to 40 MPa (reduced pressures of 1.2-8 with respect to pure O-2). Parametric studies of the effect of the thermal diffusion factor value reveal that it is minor at 10 MPa and moderate at 40 MPa, and that although the Soret term is dominated by the Fick, Dufour, and Fourier terms, it is not negligible. The influence of a cluster Nusselt number is also shown to be relatively small in the range 10(3) to 10(4), consistent with the supercritical behavior being essentially a diffusive one. All of the results show a nonlinear d(2) variation with curves having a positive curvature independent of the values of the thermal diffusion factor, the Nusselt number or the LOX/H-2 mass ratio. The approximation of a binary size cluster containing relatively a much larger number of small drops by a monodisperse cluster with a drop size based upon the surface average of the drops in the polydisperse cluster yields a good evaluation of the thermodynamic quantities in the interstitial drop region but an underestimate of the lifetime of the drops in the cluster. (C) 2001 by The Combustion Institute. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bellan, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 125-109, Pasadena, CA 91109 USA. NR 42 TC 10 Z9 10 U1 1 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD MAR PY 2001 VL 124 IS 4 BP 535 EP 550 DI 10.1016/S0010-2180(00)00217-0 PG 16 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 406MT UT WOS:000167220300001 ER PT J AU Yuan, ZG Hegde, U Faeth, GM AF Yuan, ZG Hegde, U Faeth, GM TI Effects of electric fields on non-buoyant spherical diffusion flames SO COMBUSTION AND FLAME LA English DT Article ID SOOT C1 NASA, Natl Ctr Micrograv Res, Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Michigan, Ann Arbor, MI 48109 USA. RP Yuan, ZG (reprint author), NASA, Natl Ctr Micrograv Res, Glenn Res Ctr, Cleveland, OH 44135 USA. OI Ismail, Mostafa/0000-0001-7530-9764 NR 21 TC 4 Z9 5 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD MAR PY 2001 VL 124 IS 4 BP 712 EP 716 DI 10.1016/S0010-2180(00)00215-7 PG 5 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA 406MT UT WOS:000167220300013 ER PT J AU Roberts, TW Sidilkover, D Tsynkov, SV AF Roberts, TW Sidilkover, D Tsynkov, SV TI On the combined performance of nonlocal artificial boundary conditions with the new generation of advanced multigrid flow solvers SO COMPUTERS & FLUIDS LA English DT Article DE factorizable scheme; pressure-Poisson formulation; multigrid methods; compressible flow; incompressible flow; conformal mapping; Fourier transform; mode selection; conservation on the grid; optimal convergence rate; exact solution; error profiles ID NUMERICAL-SOLUTION; CONSERVATION-LAWS; EULER EQUATIONS; EXTERNAL FLOWS; COMPUTATIONS AB We develop theoretically and implement numerically a unified flow solution methodology that combines the advantages relevant to two independent groups of methods in computational fluid dynamics that have recently proven successful: The new factorizable schemes for the equations of hydrodynamics that facilitate the construction of optimally convergent multigrid algorithms, and highly accurate global far-field artificial boundary conditions (ABCs). The primary result that we have obtained is the following. Global ABCs do not hamper the optimal (i.e., unimprovable) multigrid convergence rate pertinent to the solver. At the same time, contrary to the standard local ABCs, the solution accuracy provided by the global ABCs deteriorates very slightly or does not deteriorate at all when the computational domain shrinks, which clearly translates into substantial savings of computer resources. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Tel Aviv Univ, Sch Math Sci, IL-69978 Tel Aviv, Israel. NASA, Langley Res Ctr, Computat Modeling & Simulat Branch, Hampton, VA 23681 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Tsynkov, SV (reprint author), N Carolina State Univ, Dept Math, Box 8205, Raleigh, NC 27695 USA. NR 41 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 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD MAR PY 2001 VL 31 IS 3 BP 269 EP 308 PG 40 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 493MU UT WOS:000172227900001 ER PT J AU Williams, CP AF Williams, CP TI Quantum search algorithms in science and engineering SO COMPUTING IN SCIENCE & ENGINEERING LA English DT Article ID COMPUTATION AB The kinds of search algorithms that can run on quantum computers are qualitatively different from those that run on classical computers. As this article shows, quantum searches are thus vastly more efficient on certain kinds of problems. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM colin.p.williams@jpl.nasa.gov NR 16 TC 10 Z9 10 U1 1 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 1521-9615 EI 1558-366X J9 COMPUT SCI ENG JI Comput. Sci. Eng. PD MAR-APR PY 2001 VL 3 IS 2 BP 44 EP 51 DI 10.1109/5992.909001 PG 8 WC Computer Science, Interdisciplinary Applications SC Computer Science GA 405BA UT WOS:000167136300010 ER PT J AU Snell, EH Judge, RA Crawford, L Forsythe, EL Pusey, ML Sportiello, M Todd, P Bellamy, H Lovelace, J Cassanto, JM Borgstahl, GEO AF Snell, EH Judge, RA Crawford, L Forsythe, EL Pusey, ML Sportiello, M Todd, P Bellamy, H Lovelace, J Cassanto, JM Borgstahl, GEO TI Investigating the effect of impurities on macromolecule crystal growth in microgravity SO CRYSTAL GROWTH & DESIGN LA English DT Article ID EGG-WHITE LYSOZYME; PROTEIN CRYSTAL; THAUMATIN CRYSTALS; CRYSTALLIZATION; TEMPERATURE; PURIFICATION; SPACEHAB-01; RESOLUTION; PERFECTION; APPARATUS AB Chicken egg-white lysozyme (CEWL) crystals were grown in microgravity and on the ground in the presence of various amounts of a naturally occurring lysozyme dimer impurity. No significant favorable differences in impurity incorporation between microgravity and ground crystal samples were observed. At low impurity concentration the microgravity crystals preferentially incorporated the dimer. The presence of the dimer in the crystallization solutions in microgravity reduced crystal size, increased mosaicity, and reduced the signal-to-noise ratio of the X-ray data. Microgravity samples proved more sensitive to impurity. Accurate indexing of the reflections proved critical to the X-ray analysis. The largest crystals with the best X-ray diffraction properties were grown from pure solution in microgravity. C1 NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Colorado, Dept Chem Engn, Boulder, CO 80309 USA. Stanford Synchrotron Radiat Lab, Menlo Pk, CA 94025 USA. Univ Toledo, Dept Chem, Toledo, OH 43606 USA. Instrumentat Technol Associates, Exton, PA 19341 USA. RP Snell, EH (reprint author), NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 44 TC 28 Z9 28 U1 2 U2 6 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 1528-7483 J9 CRYST GROWTH DES JI Cryst. Growth Des. PD MAR-APR PY 2001 VL 1 IS 2 BP 151 EP 158 DI 10.1021/cg0055474 PG 8 WC Chemistry, Multidisciplinary; Crystallography; Materials Science, Multidisciplinary SC Chemistry; Crystallography; Materials Science GA 519CJ UT WOS:000173707100008 ER PT J AU Zhu, S Su, CH Cochrane, JC Lehoczky, S Muntele, I Ila, D AF Zhu, S Su, CH Cochrane, JC Lehoczky, S Muntele, I Ila, D TI Growth of carbon nanostructure materials using laser vaporization SO DIAMOND AND RELATED MATERIALS LA English DT Article; Proceedings Paper CT 11th European Conference on Diamond, Diamond-like Materials, Carbon Nanotubes, Nitrides and Silicon Carbide (Diamond 2000) CY SEP 03-08, 2000 CL OPORTO, PORTUGAL SP De Beers Ind Diamonds (UK) Ltd, GFD Gesell Diamantprod mbH, Philips Res Labs, Elsevier Sci DE carbon; structure; X-ray diffraction; Raman spectroscopy ID NANOTUBES; TEMPERATURE; ABLATION AB Carbon nanoparticles and nanotubes have been synthesized on Si substrates using pulsed laser vaporization. Two kinds of targets were used to grow the nanostructural materials. One was a pure carbon target and the other was carbon target containing Ni and Co catalysts, The growth temperatures were 600-1000 degreesC and the argon pressure was 500 torr. Samples were characterized by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Materials containing carbon nanocrystal particles could be observed using a pure carbon target when a thin Ni film was deposited on (100) Si substrates prior to growing carbon materials. The carbon nanotubes (CNT) were obtained in carbon soot when the target contained catalysts. By comparing the Raman radial breathing modes of the CNT grown at various temperatures, it was found that the density of the CNT was lower and the strongest Raman peak was slightly blue-shifted in samples grown at lower temperatures. (C) 2001 Elsevier Science B,V, Ah rights reserved. C1 NASA, George C Marshall Space Flight Ctr, USRA, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Sci Directorate, Micrograv Sci & Applicat Dept, Huntsville, AL 35812 USA. Alabama A&M Univ, Ctr Irradiat Mat, Normal, AL 35762 USA. RP Zhu, S (reprint author), NASA, George C Marshall Space Flight Ctr, USRA, Huntsville, AL 35812 USA. NR 10 TC 9 Z9 9 U1 1 U2 4 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 MAR-JUL PY 2001 VL 10 IS 3-7 SI SI BP 1190 EP 1194 DI 10.1016/S0925-9635(00)00486-6 PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA 432ZJ UT WOS:000168730600170 ER PT J AU Park, HG Dabiri, D Gharib, M AF Park, HG Dabiri, D Gharib, M TI Digital particle image velocimetry/thermometry and application to the wake of a heated circular cylinder SO EXPERIMENTS IN FLUIDS LA English DT Article ID THERMOCHROMIC LIQUID-CRYSTALS; CALIBRATION AB Digital particle image velocimetry/thermometry (DPIV/T) is a technique whereby the velocity and temperature fields are obtained using thermochromic liquid crystal (TLC) seeding particles in water. In this paper, the uncertainty levels associated with temperature and velocity measurements using DPIV/T are studied. The study shows that large uncertainties are encountered when the temperature is measured from individual TLC particles. Therefore, an averaging procedure is presented which can reduce the temperature uncertainties. The uncertainty is reduced by computing the average temperature of the particles within the common specified sampling window used for standard DPIV. Using this procedure, the velocity and temperature distributions of an unsteady wake behind a heated circular cylinder are measured experimentally at Re = 610. The instantaneous DPIV/T measurements are shown to be useful for computing statistical flow quantities, such as mean and velocity-temperature correlations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Grad Aeronaut Labs, Pasadena, CA 91125 USA. RP Park, HG (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 39 Z9 39 U1 0 U2 7 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD MAR PY 2001 VL 30 IS 3 BP 327 EP 338 DI 10.1007/s003480000199 PG 12 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA 411ZB UT WOS:000167528600012 ER PT J AU Livesey, NJ Waters, JW Khosravi, R Brasseur, GP Tyndall, GS Read, WG AF Livesey, NJ Waters, JW Khosravi, R Brasseur, GP Tyndall, GS Read, WG TI Stratospheric CH3CN from the UARS microwave limb sounder SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HYDROGEN-CYANIDE; ACETONITRILE; TROPOSPHERE; ACETONE; HCN AB CH3CN in the stratosphere has been measured by the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS), providing the first global CH3CN dataset. The MLS observations are in broad agreement with past high and midlatitude observations of CH3CN, although concentrations are a little larger than previously observed. In the tropics, where CH3CN has not up to now been measured, a persistent 'peak' in the profiles is seen around 22hPa, which may be evidence of a tropical stratospheric CH3CN source. Comparisons are made with the NCAR SOCRATES model, including runs having an artificial tropical stratospheric CH3CN source. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Ctr Atmospher Res, Div Atmospher Chem, Boulder, CO USA. Max Planck Inst Meteorol, Hamburg, Germany. RP Livesey, NJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 22 TC 18 Z9 18 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 MAR 1 PY 2001 VL 28 IS 5 BP 779 EP 782 DI 10.1029/2000GL012144 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 406RV UT WOS:000167229700009 ER PT J AU Cavalieri, DJ Hakkinen, S AF Cavalieri, DJ Hakkinen, S TI Arctic climate and atmospheric planetary waves SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SEA-ICE; NORTH-ATLANTIC; CIRCULATION; OCEAN; VARIABILITY; PACIFIC AB Analysis of a fifty-year record (1946-1995) of monthly-averaged sea level pressure data provides a link between the phases of planetary-scale sea level pressure waves and Arctic Ocean and ice variability. Results of this analysis show: (1) a breakdown of the dominant wave 1 pattern in the late 1960's, (2) shifts in the mean phase of waves 1 and 2 since this breakdown, (3) an eastward shift in the phases of both waves 1 and 2 during the years of simulated cyclonic Arctic Ocean circulation relative to their phases during the years of anticyclonic circulation, (4) a strong decadal variability of wave phase associated with simulated Arctic Ocean circulation changes. Finally, the Arctic atmospheric circulation patterns that emerge when waves 1 and 2 are in their extreme eastern and western positions suggest an alternative approach for determining significant forcing patterns of sea ice and high-latitude variability. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Cavalieri, DJ (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Code 971, Greenbelt, MD 20771 USA. RI Hakkinen, Sirpa/E-1461-2012 NR 10 TC 16 Z9 17 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 MAR 1 PY 2001 VL 28 IS 5 BP 791 EP 794 DI 10.1029/2000GL011855 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 406RV UT WOS:000167229700012 ER PT J AU Yang, JY Comiso, J Krishfield, R Honjo, S AF Yang, JY Comiso, J Krishfield, R Honjo, S TI Synoptic storms and the development of the 1997 warming and freshening event in the Beaufort Sea SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ARCTIC-OCEAN; ICE; LAYER; HALOCLINE; MODEL AB The climatic state in the Beaufort Sea in 1997 was characterized by warmer atmosphere, smaller areal coverage of sea ice in summer than average, and an oceanic mixed layer with a relatively low salinity that persisted into fall and and early winter. The most remarkable change occurred near the end of 1997 when both salinity and temperature in the upper layer varied dramatically in a short-time period. The evolution of the air-sea-ice condition was observed by an autonomous buoy. The buoy observation revealed that deep mixing that penetrated through the Arctic halocline occurred in response to enhanced wind-stress forcing associated with an intense storm and was mainly responsible for the abrupt change of temperature and salinity in the mixed layer near the end of 1997. Similar events were inferred from storms in the Eurasian basin in 1994. We postulate that synoptic storms plays a very important role in the variations of the heat and salt budgets in the upper Arctic Ocean. C1 Woods Hole Oceanog Inst, Dept Phys Oceanog, Woods Hole, MA 02543 USA. NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. Woods Hole Oceanog Inst, Dept Marine Geol & Geophys, Woods Hole, MA 02543 USA. RP Yang, JY (reprint author), Woods Hole Oceanog Inst, Dept Phys Oceanog, Woods Hole, MA 02543 USA. NR 10 TC 14 Z9 14 U1 1 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 MAR 1 PY 2001 VL 28 IS 5 BP 799 EP 802 DI 10.1029/2000GL011896 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 406RV UT WOS:000167229700014 ER PT J AU Oieroset, M Mitchell, DL Phan, TD Lin, RP Acuna, MH AF Oieroset, M Mitchell, DL Phan, TD Lin, RP Acuna, MH TI Hot diamagnetic cavities upstream of the Martian bow shock SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID PHOBOS OBSERVATIONS; WAVE OBSERVATIONS; SOLAR-WIND; MARS; PLASMA; DEIMOS AB We present Mars Global Surveyor (MGS) observations of hot diamagnetic cavities upstream of the Martian bow shock. The events are characterized by a region of turbulent magnetic field, high electron temperature, and densities at or below the ambient solar wind density. The region of high temperature is flanked by layers of high magnetic field and electron density and is accompanied by a rotation in the interplanetary magnetic field (IMF). We suggest that the events are generated by interplanetary discontinuities interacting with the Martian bow shock, i.e., the events are the Martian counterpart to the hot flow anomalies observed upstream of the Earth's bow shock. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Oieroset, M (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NR 22 TC 29 Z9 29 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 MAR 1 PY 2001 VL 28 IS 5 BP 887 EP 890 DI 10.1029/2000GL012289 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 406RV UT WOS:000167229700036 ER PT J AU Levin, SM Bolton, SJ Gulkis, SL Klein, MJ Bhattacharya, B Thorne, RM AF Levin, SM Bolton, SJ Gulkis, SL Klein, MJ Bhattacharya, B Thorne, RM TI Modeling Jupiter's synchrotron radiation SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETIC-FIELD; MAGNETOSPHERE AB We have constructed a computer model to simulate synchrotron emission from relativistic electrons trapped in Jupiter's magnetic field. The computer program generates the four Stokes parameters of the synchrotron emission for assumed electron distributions and magnetic field models. The resulting two dimensional Stokes parameter maps can be compared directly with ground based observations. We use magnetic field models derived from spacecraft measurements, and tailor the electron distributions to fit synchrotron observations. The gross features of data from both VLA and single-dish observations are fit by a longitudinally symmetric particle distribution. We suggest that higher order terms in the magnetic field, coupled with relativistic beaming effects of synchrotron radiation, are primarily responsible for the observed rotational asymmetry. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90024 USA. RP Levin, SM (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-506, Pasadena, CA 91109 USA. NR 13 TC 10 Z9 10 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 MAR 1 PY 2001 VL 28 IS 5 BP 903 EP 906 DI 10.1029/2000GL012087 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 406RV UT WOS:000167229700040 ER PT J AU Bolton, SJ Levin, SM Gulkis, SL Klein, MJ Sault, RJ Bhattacharya, B Thorne, RM Dulk, GA Leblanc, Y AF Bolton, SJ Levin, SM Gulkis, SL Klein, MJ Sault, RJ Bhattacharya, B Thorne, RM Dulk, GA Leblanc, Y TI Divine-Garrett model and Jovian synchrotron emission SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RADIAL DIFFUSION-MODELS; ENERGETIC ELECTRONS; JUPITER; STATE AB Simulations of synchrotron emission from relativistic electrons trapped in Jupiter's magnetic field are used to evaluate the energetic electron distribution of the Divine-Garrett Jupiter radiation belt model at radial distances less than 4 Jovian radii. The fundamental characteristic of synchrotron emission, narrow beaming from gyrating electrons, provides the basis for constraints on both the magnetic field and the distribution of particles in the inner magnetosphere. A comparison between model results and observations is presented. The results suggest the Divine Garrett model significantly underestimates the number of relativistic electrons (> 1 MeV) present in Jupiter's inner magnetosphere. The results also indicate that the pitch angle distribution of relativistic electrons in the Jovian radiation belts is different than assumed in the Divine-Garrett model. These results have important implications for the development of self-consistent models of Jupiter's magnetosphere and the planning of future missions requiring close flybys of Jupiter. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CSIRO, Epping, NSW, Australia. Univ Calif Los Angeles, Dept Atmospher Sci, Los Angeles, CA 90024 USA. Observ Paris, Meudon, France. RP Bolton, SJ (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,MS 169-506, Pasadena, CA 91109 USA. NR 17 TC 6 Z9 6 U1 1 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 MAR 1 PY 2001 VL 28 IS 5 BP 907 EP 910 DI 10.1029/2000GL012071 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 406RV UT WOS:000167229700041 ER PT J AU Zhou, XW Russell, CT Le, G Fuselier, SA Scudder, JD AF Zhou, XW Russell, CT Le, G Fuselier, SA Scudder, JD TI Factors controlling the diamagnetic pressure in the polar cusp SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HIGH-LATITUDE; HIGH-ALTITUDE; MAGNETOPAUSE; MISSION; ANGLE; SHAPE AB The solar wind has direct access to the polar cusps although the plasma may be processed first by reconnection. The energy density of the polar cusp plasma is expected to be controlled by the component of the unshocked solar wind dynamic pressure along the normal to the cusp/magnetosheath interface. The factors controlling this angle are the local time of the observation and the dipole tilt angle. We use Polar observations of the magnetic field and plasma to identify the polar cusp, and the change in magnetic pressure in the cusp to calculate the peak diamagnetic pressure of the plasma. As expected this pressure is directly proportional to the solar wind dynamic pressure in quantitative agreement with expectations. When the dipole tilts more toward the Sun, the angle between the solar wind flow and the magnetopause normal is smaller, and the pressure is higher, and when it tilts away from the Sun, the pressure is less. For large tilts away from the Sun, for local times far away from noon and for low solar wind dynamic pressure the diamagnetic depression marking the polar cusp is too weak to be resolved by the magnetometer. C1 Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. Lockheed Martin, Ctr Adv Technol, Palo Alto, CA 94304 USA. NASA, Goddard Space Flight Ctr, Electrodynam Branch, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA. Univ Iowa, Dept Phys, Iowa City, IA 52241 USA. RP Zhou, XW (reprint author), Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. RI Le, Guan/C-9524-2012; Scudder, Jack/D-8417-2013; OI Le, Guan/0000-0002-9504-5214; Scudder, Jack/0000-0001-7975-5630; Russell, Christopher/0000-0003-1639-8298 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 MAR 1 PY 2001 VL 28 IS 5 BP 915 EP 918 DI 10.1029/2000GL012306 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 406RV UT WOS:000167229700043 ER PT J AU Connell, JW Watson, KA AF Connell, JW Watson, KA TI Space environmentally stable polyimides and copolyimides derived from bis(3-aminophenyl)-3,5-di(trifluoromethyl)phenylphosphine oxide SO HIGH PERFORMANCE POLYMERS LA English DT Article ID POLY(ARYLENE ETHER HETEROCYCLE)S; ATOMIC OXYGEN EXPOSURE; PLASMA; POLYMERS; FILMS AB Polyimides with a unique combination of properties including low colour in thin films, atomic oxygen (AO) resistance, ultra-violet (UV) radiation resistance, solubility in organic solvents in the imide form, high glass transition (T-g) temperatures, and high thermal stability have been prepared and characterized. Polyimides were prepared by reacting a novel aromatic diamine, bis(3-aminophenyl)-3,5-di(trifluoromethyl)phenylphosphine oxide, with various aromatic dianhydrides in a polar aprotic solvent. Copolymers were prepared by the addition of a second diamine. The solubility of the polymers in the imide form as well as the colour density of thin films was dependent upon the chemical structure of the dianhydride and the additional diamine. Thin films (25-50 mum thick) prepared by solution casting of amide acid or imide solutions exhibited very low colour and high optical transparency as determined by UV/visible spectroscopy. The polymers exhibited T-g values greater than 200 degreesC depending upon the structure of the dianhydride and temperatures of 5% weight loss similar to 500 degreesC in air as determined by dynamic thermogravimetric analysis (TGA). Thin films coated with silver/inconel were exposed to a high fluence of AO and 1000 equivalent solar hours of UV radiation. The effects of these exposures on optical properties were minor. These space environmentally durable polymers are potentially useful in a variety of applications on spacecraft such as thin film membranes on antennae, second surface mirrors, thermal/optical coatings and multi-layer thermal insulation (MLI) blanket materials. The chemistry, physical and mechanical properties of the polymers as well as their responses to AO and UV exposure will be discussed. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Connell, JW (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 17 TC 23 Z9 25 U1 1 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD MAR PY 2001 VL 13 IS 1 BP 23 EP 34 DI 10.1088/0954-0083/13/1/303 PG 12 WC Polymer Science SC Polymer Science GA 420GY UT WOS:000167998300003 ER PT J AU Alexander, MA Hill, DJT Connell, JW Watson, KA AF Alexander, MA Hill, DJT Connell, JW Watson, KA TI A study of the oxidation of two aromatic polyimide fluoropolymers containing phenylphosphine oxide by a water plasma and gamma-radiolysis in air SO HIGH PERFORMANCE POLYMERS LA English DT Article ID DEGRADATION; RADIATION AB The oxidation of two fluorinated polyimides containing phenylphosphine oxide units, TOR-RC and TOR-RC ODPA, have been studied at 300 K for treatment by a water plasma and gamma -radiolysis in air. The changes in the O 1s/C 1s ratios obtained from x-ray photoelectron spectroscopy (XPS) analysis showed that for exposure to the water plasma the ratio increases at short exposure times and then levels to a constant value. Evidence for the formation of phosphate species was also obtained from the XPS analyses. Similar observations were made for gamma -radiolysis of the polymers in air. The polymers containing phenylphosphine oxide were found to be more resistant to oxidation in the water plasma than Kapton(R). Radiolysis of the polymers in air to high doses were also accompanied by a red shift in the visible absorption spectra. C1 Univ Queensland, Dept Chem, Polymer Mat & Radiat Grp, Brisbane, Qld 4072, Australia. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hill, DJT (reprint author), Univ Queensland, Dept Chem, Polymer Mat & Radiat Grp, Brisbane, Qld 4072, Australia. NR 22 TC 4 Z9 4 U1 3 U2 5 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-0083 J9 HIGH PERFORM POLYM JI High Perform. Polym. PD MAR PY 2001 VL 13 IS 1 BP 55 EP 65 DI 10.1088/0954-0083/13/1/306 PG 11 WC Polymer Science SC Polymer Science GA 420GY UT WOS:000167998300006 ER PT J AU Konopliv, AS Asmar, SW Carranza, E Sjogren, WL Yuan, DN AF Konopliv, AS Asmar, SW Carranza, E Sjogren, WL Yuan, DN TI Recent gravity models as a result of the lunar prospector mission SO ICARUS LA English DT Article DE lunar, gravity; spherical harmonics; Doppler ID VENUS GRAVITY; TRACKING DATA; 180TH DEGREE; ORDER MODEL; CLEMENTINE; FIELD; MOON; MAGELLAN AB The lunar gravity field is determined from the tracking data of previous missions to the Moon with the 1998-1999 Lunar Prospector (LP) mission being the major contributor. LP provided the first measurement of the gravity field in a low polar circular orbit giving complete coverage at high resolution for the entire lunar nearside. However, since there is no direct measurement of the lunar farside from LP or any other mission, gravity details for the farside gravity are greatly limited. Even so, it has become apparent that there are mascons on the farside of the Moon together with the newly identified mascons in the LP data for the lunar nearside. The extended mission low-altitude data (at times less than 10 km above the surface) has gravity information for the nearside to nearly degree and order 180, The 100th-degree lunar gravity models (LP100J and LP100K) extract most of the information from the nominal 100-km altitude. A 165th degree model LP165P attempts to model the extended mission data with some but limited success. This model provides a smooth solution without aliasing when evaluated up to degree 110 allowing for resolution of numerous craters. In addition, a preliminary solution for the lunar Love number is k(2) = 0.026 +/- 0.003. (C) 2001 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Konopliv, AS (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 42 TC 206 Z9 250 U1 4 U2 10 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 MAR PY 2001 VL 150 IS 1 BP 1 EP 18 DI 10.1006/icar.2000.6573 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 421NY UT WOS:000168071500001 ER PT J AU Nixon, CA Irwin, PGJ Calcutt, SB Taylor, FW Carlson, RW AF Nixon, CA Irwin, PGJ Calcutt, SB Taylor, FW Carlson, RW TI Atmospheric composition and cloud structure in Jovian 5-mu m hotspots from analysis of Galileo NIMS measurements SO ICARUS LA English DT Article DE Jupiter, atmosphere; abundances, atmospheres; atmospheres, composition; infrared observations; spectroscopy ID TROPOSPHERIC GAS-COMPOSITION; NORTH EQUATORIAL BELT; VOYAGER IRIS DATA; JUPITERS ATMOSPHERE; THERMAL-RADIATION; ABUNDANCE; SPECTROMETER; WATER; NH3; SPECTROSCOPY AB NIMS is the Near-Infrared Mapping Spectrometer on board the Galileo spacecraft in jovian orbit. We have selected four maps of warm-to-hot regions of the North Equatorial Belt (NEB) for study, analyzing the spectra emerging in the low-opacity 5-mum window Two methods for calculating the spectrum have been used. The first is a full-scattering radiative transfer forward model that is slow but accurate. The second method calculates spectra by interpolating on a grid of spectra precalculated using the first method for a range of model atmospheres. This method of forward calculation is more suited to analysis of large data sets where application of the full radiative transfer in every instance would be computationally prohibitive. The faster method is verified against the first before being used alone. A retrieval (inversion) algorithm is then used to match model spectra to data and obtain values for cloud opacities and gas mixing ratios. We first sum spectra with similar peak radiances to produce mean spectra representative of brighter and darker (at 5 mum) regions of the maps. These coadded spectra are then analyzed with the fast retrieval code to obtain the average variations in atmospheric parameters from the center to the edges of the hotspots. These analyses confirm that 5-mum hotspots are relatively cloud free, and that a medium level(1.5-bar) cloud layer of large NH4SH particles is the main absorber at these wavelengths. Variations in water vapor relative humidity and high (0.5-bar) ammonia cloud opacity are also derived. We then analyze single spectra over wide areas to produce spatial maps of parameter variations. We find that models that do not include a deep water cloud (similar to4 bar) do not match all the spectra to within the noise level. A deep water cloud therefore seems to be present in localized areas, toward the edges of the hotspot regions. We examine these findings in the light of results from other Galileo instruments, concluding that the deep cloud observed by the SSI instrument at several locations is likely to be the deep water cloud required by the NIMS data. e zool Academic Press. C1 Univ Oxford, Oxford, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Nixon, CA (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Nixon, Conor/A-8531-2009; OI Nixon, Conor/0000-0001-9540-9121; Calcutt, Simon/0000-0002-0102-3170 NR 38 TC 17 Z9 17 U1 0 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 MAR PY 2001 VL 150 IS 1 BP 48 EP 68 DI 10.1006/icar.2000.6561 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 421NY UT WOS:000168071500004 ER PT J AU Adams, FC Laughlin, G AF Adams, FC Laughlin, G TI Constraints on the birth aggregate of the solar system SO ICARUS LA English DT Article DE open clusters and associations, general; stars, formation; Solar System, formation ID MOLECULAR CLOUDS; STAR-FORMATION; CLUSTERS; PHOTOEVAPORATION; ENCOUNTERS; PLANETS; MODELS; NEBULA; ORION; DISKS AB Using the observed properties of our Solar System, in particular the isotopic compositions of meteorites and the regularity of the planetary orbits, we constrain the star formation environment of the Sun within the scenario of (external) radioactive enrichment by a massive star. This calculation yields a probability distribution for the number of stars in the solar birth aggregate. The Sun is most likely to have formed within a stellar group containing N = (N) approximate to 2000 +/- 1100 members. The a Priori probability of a star forming in this type of environment is p approximate to 0.0085; i.e., only about 1 out of 120 solar systems are expected to form under similar conditions. We discuss additional implications of this scenario, including possible effects from the radiation fields provided by the putative cluster environment and dynamical disruption of the Kuiper Belt. The constraints of this paper place tight restrictions on the properties of the solar birth aggregate for the scenario of external enrichment by a massive star; alternately, these tight constraints slightly favor a self-enrichment scenario for the short-lived radioactive species. (C) 2001 Academic Press. C1 Univ Michigan, Dept Phys, Michigan Ctr Theoret Phys, Ann Arbor, MI 48109 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Adams, FC (reprint author), Univ Michigan, Dept Phys, Michigan Ctr Theoret Phys, Ann Arbor, MI 48109 USA. NR 44 TC 91 Z9 90 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 MAR PY 2001 VL 150 IS 1 BP 151 EP 162 DI 10.1006/icar.2000.6567 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 421NY UT WOS:000168071500011 ER PT J AU Rappaport, NJ Giampieri, G Anderson, JD AF Rappaport, NJ Giampieri, G Anderson, JD TI Perturbations of a spacecraft orbit during a hyperbolic flyby SO ICARUS LA English DT Article ID INTERNAL STRUCTURE AB A first-order perturbation theory exists for the flyby problem with the Born approximation as the reference orbit (J. D. Anderson and G. Giampieri 1999, Icarus 138, 309-318, AG thereafter). This theory is applicable when the deflection parameter mu /bv(2) (where mu is the product of the gravitational constant by the body's mass, b the impact parameter, and v the velocity of the flyby) is small. Here rye present an analytical theory for the motion of a spacecraft with the hyperbola as the reference orbit. The perturbations consist of the next term after the monopole in the central body's gravitational exterior potential function, represented by the quadrupole harmonic coefficients C-20 and C-22. The perturbations of the hyperbolic elements are expressed in closed form, without involving infinite series, as functions of the unperturbed orbital elements. We compare results of the new theory with AG's theory. We find that AG's theory can be improved by a simple modification, and by correcting a sign error in the C-22 term in the potential function. The effects of the body's rotation on the perturbations are discussed, and new results pertaining to AG's approach are given. (C) 2001 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ London Imperial Coll Sci Technol & Med, Blackett Lab, Space & Atmospher Phys Grp, London SW7 2BW, England. RP Rappaport, NJ (reprint author), CALTECH, Jet Prop Lab, Mail Stop 301-150, Pasadena, CA 91109 USA. NR 12 TC 3 Z9 3 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 MAR PY 2001 VL 150 IS 1 BP 168 EP 180 DI 10.1006/icar.2000.6559 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 421NY UT WOS:000168071500013 ER PT J AU Yanamandra-Fisher, PA Orton, GS Fisher, BM Sanchez-Lavega, A AF Yanamandra-Fisher, PA Orton, GS Fisher, BM Sanchez-Lavega, A TI Saturn's 5.2-mu m cold spots: Unexpected cloud variability SO ICARUS LA English DT Article DE Saturn, atmosphere; jovian planets; radiative transfer; spectrophotometry AB New 5.2-mum thermal images of Saturn's clouds reveal a strong axisymmctric banded structure centered at 45 degreesS with discrete cold spots about 30,000-50,000 km long that: (i) lower the similar to 180-K brightness temperature by 8-10 K; (ii) rotate at a rate that is consistent with cloud-tracked zonal winds; and (iii) exhibit no correlation with structures seen in reflected sunlight. They are explained by variations of optical thickness of clouds just below the 1-bar level. (C) 2001 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Basque Country, Dept Fis Aplicada LETS Ingn, Bilbao 48013, Spain. RP Yanamandra-Fisher, PA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM padma@durga.jpl.nasa.gov NR 7 TC 15 Z9 15 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD MAR PY 2001 VL 150 IS 1 BP 189 EP 193 DI 10.1006/icar.2000.6580 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 421NY UT WOS:000168071500015 ER PT J AU Shenai, K Neudeck, PG Neudeck, PG AF Shenai, K Neudeck, PG Neudeck, PG TI Design and technology of compact high-power converters SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB New material technologies such as Silicon Carbide (SiC) are promising in the development of compact high-power converters for next-generation power electronics applications, This paper presents an optimized converter design approach that takes into consideration non-linear interactions among various converter components, source and load. It is shown that with the development of high-temperature, high-power SiC power module technology, magnetic components and capacitors become important technology challenges, and cannot be ignored. A 50% improvement in power density is calculated for a 100V-2kV, 7kW SiC DC-DC power converter operating at 150 degreesC compared to a silicon power converter. The SiC power converter can be operated at junction temperatures in excess of 300 degreesC (as compared to 150 degreesC for a silicon power converter) with reasonable efficiency that potentially leads to a significant reduction in thermal management. C1 Univ Illinois, Dept Elect Engn & Comp Sci, Chicago, IL 60607 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Univ Illinois, Dept Elect Engn & Comp Sci, 1120 SEO M-C 154,851 Morgan St, Chicago, IL 60607 USA. NR 19 TC 10 Z9 10 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0885-8985 EI 1557-959X J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD MAR PY 2001 VL 16 IS 3 BP 27 EP 31 DI 10.1109/62.911318 PG 5 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA 414GD UT WOS:000167657100007 ER PT J AU Noginov, MA Loutts, GB Lucas, BD Fider, D Higgins, PT Truong, A Noginova, N Barnes, NP Kuck, S AF Noginov, MA Loutts, GB Lucas, BD Fider, D Higgins, PT Truong, A Noginova, N Barnes, NP Kuck, S TI Development of Nd-doped solid-state laser materials for 944-nm operation SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article DE apatite crystals; laser crystals; Nd3+ ions; solid-state lasers ID STIMULATED-EMISSION; ABSORPTION; PERFORMANCE; CRYSTALS; SPECTRA AB We have grown neodymium-doped mixed apatite crystals [(Sr1-xBax)(5)(PO4)(3)F, Sr-5(P1-xVxO4)(3)F, and Ba-5(P1-xVxO4)(3)F] and spectroscopically studied them as potential gain media for a laser source for atmospheric water sensing operating at 944.11 nm. We conclude that an appropriate apatite host material for a 914.11-nm laser should be a mixture of Sr-5(PO4)(3)F With a small fraction of Ba-5(PO4)(3)F. Precise wavelength tuning around 944.11 nm can be accomplished by varying the host composition, temperature, and threshold population inversion. In apatite crystals of mixed composition, the amplified spontaneous emission (ASE) loss at 1.06 mum is predicted to be significantly smaller than that in the end members. C1 Norfolk State Univ, Ctr Mat Res, Norfolk, VA 23504 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. Inst Laser Phys, D-20355 Hamburg, Germany. RP Noginov, MA (reprint author), Norfolk State Univ, Ctr Mat Res, Norfolk, VA 23504 USA. NR 19 TC 5 Z9 5 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD MAR PY 2001 VL 37 IS 3 BP 469 EP 481 DI 10.1109/3.910459 PG 13 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA 409DV UT WOS:000167370000021 ER PT J AU Prassler, E Scholz, J Fiorini, P AF Prassler, E Scholz, J Fiorini, P TI A robotic wheelchair for crowded public environments SO IEEE ROBOTICS & AUTOMATION MAGAZINE LA English DT Article DE robotics wheelchair; assistive robots; navigation in time-varying environments; real-time motion detection; tracking; prediction AB MAid combines narrow- and wide-area navigation behaviors for traversing varying environments while retaining user independence and preventing fatigue. C1 Res Inst Appl Knowledge Proc, Dept Autonomous Syst, D-89081 Ulm, Germany. CALTECH, NASA, Jet Prop Lab, Pasadena, CA 91125 USA. RP Prassler, E (reprint author), Res Inst Appl Knowledge Proc, Dept Autonomous Syst, Helmholtzstr 16, D-89081 Ulm, Germany. RI Fiorini, Paolo/A-2603-2012 NR 16 TC 51 Z9 54 U1 0 U2 11 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 MAR PY 2001 VL 8 IS 1 BP 38 EP 45 DI 10.1109/100.924358 PG 8 WC Automation & Control Systems; Robotics SC Automation & Control Systems; Robotics GA 428CJ UT WOS:000168443300006 ER PT J AU Pogorzelski, RJ AF Pogorzelski, RJ TI On a simple method of obtaining sidelobe reduction over a wide angular range in one and two dimensions SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article DE injection locking; phased arrays; sidelobe control; voltage-controlled oscillators ID ARRAYS AB A patented technique for suppressing the sidelobes of an array antenna is considered. This technique involves the addition of two elements, one at each end of the array, which together produce an interferometer pattern used for cancellation of side-lobes, It is shown here that the technique is most effective for uniform illumination and that there then exists an optimum fixed position for the added elements, The amplitude of the excitation of the auxiliary elements determines the angular location of the region of sidelobe reduction while the phase of the excitation tracks the beamsteering phase of the array. Thus, this technique is seen to be easily implemented in an array controlled by coupled oscillators, The technique generalizes in a straightforward manner to two-dimensional (2-D) arrays in which case a set of auxiliary elements on the perimeter of the array is required. A 2-D oscillator controlled array of this type is described here with which one can produce a main beam and a sidelobe suppression region that can be independently positioned anywhere in a hemisphere provided they do not coincide. 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 5 TC 7 Z9 7 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD MAR PY 2001 VL 49 IS 3 BP 475 EP 482 DI 10.1109/8.918624 PG 8 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 426PT UT WOS:000168358100021 ER PT J AU Bumble, B LeDuc, HG Stern, JA Megerian, KG AF Bumble, B LeDuc, HG Stern, JA Megerian, KG TI Fabrication of Nb/Al-N-x/NbTiN junctions for SIS mixer applications SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE AlN; niobium; NbTiN; superconductor device; SIS mixers; THz detector ID 1 THZ; NOISE AB We discuss fabrication and characteristics of superconductor-insulator-superconductor (SIS) junctions which typically exhibit a 3.5 mV sum-gap voltage. Junctions have a sub-gap to normal state resistance ratio of R-SG / R-N = 27 for resistance - area products down to R(N)A = 8 Omega mum(2) and high quality junctions have been produced with R(N)A products as low as 4 Omega mum(2), The device structure incorporates a Nb base electrode, a tunnel barrier formed by plasma nitridation of a thin Al proximity layer, and a NbTiN counter-electrode, Results for all Nb junctions with high current density aluminum-nitride barriers are also shown. Nitridation of the aluminum layer is investigated by control of the de floating potential on a separate rf driven electrode in the vacuum process chamber. Devices are integrated to a mixer antenna structure incorporating NbTiN as a ground plane. The wire circuit layer can be either normal metal or NbTiN, Annealing results show improved I-V characteristics with increased R(N)A products. Recent receiver measurements employing these junctions exhibit low noise performance up to 900 GHz. C1 CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, Pasadena, CA 91109 USA. RP Bumble, B (reprint author), CALTECH, Jet Prop Lab, Ctr Space Microelect Technol, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 11 TC 31 Z9 31 U1 1 U2 14 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 76 EP 79 DI 10.1109/77.919288 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400007 ER PT J AU Fleet, E Gilbertson, A Chatraphorn, S Tralshawala, N Weinstock, H Wellstood, FC AF Fleet, E Gilbertson, A Chatraphorn, S Tralshawala, N Weinstock, H Wellstood, FC TI Imaging defects in Cu-clad NbTi wire using a high-T-c scanning SQUID microscope SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE non-destructive evaluation; SQUID; superconducting; wires ID QUANTUM INTERFERENCE DEVICE AB We have used a sensitive magnetic microscope based on the de Superconducting Quantum Interference Device (SQUID) to examine room-temperature samples of Cu-cladNbTi wire, Our SQUID microscope allows the wire (in air at room temperature) to be brought to within about 0.05 mm of the SQUID, although typically the separation is 0.3-0.4 mm, The wires have round or rectangular cross-sections and are about 2 mm across, With the wire aligned parallel to the x-direction in the x-y scanning plane we apply currents of a few mA through the wire at a frequency of a few hundred Hz, and image the x-component of the magnetic field. Defects cause a redistribution of current and corresponding features in the magnetic field image. We show images of wires, and discuss the advantages of using the parallel component of the field. C1 Univ Maryland, Ctr Superconduct Res, Dept Phys, College Pk, MD 20742 USA. Raytheon ITSS, Lanham, MD USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USAF, Off Sci Res, Arlington, VA 22203 USA. RP Fleet, E (reprint author), Univ Maryland, Ctr Superconduct Res, Dept Phys, College Pk, MD 20742 USA. RI Joint Quantum Institute, NIST/UMD/H-4494-2011 NR 9 TC 3 Z9 4 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 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 215 EP 218 DI 10.1109/77.919322 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400041 ER PT J AU Saenz, EM Subramanyam, G Van Keuls, FW Chen, CL Miranda, FA AF Saenz, EM Subramanyam, G Van Keuls, FW Chen, CL Miranda, FA TI Fixed-frequency and frequency-agile (Au, HTS) microstrip bandstop filters for L-band applications SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE L-band Bandstop Filter; High Temperature Superconducting (HTS) thin films; LaAlO3 substrates; ferroelectric thin films; tunable filters ID THIN-FILMS AB In this work, we report on the performance of a highly selective, compact 1.83x2.08 cm(2) (similar to0.72x0.82 in.(2)) microstrip line bandstop filter of YBa2Cu3O7-delta (YBCO) on LaAlO3 (LAO) substrate, The filter is designed for a center frequency of 1.623 GHz for a bandwidth at 3 dB from reference baseline of less than 5.15 MHz, and a bandstop rejection of 30 dB or better. The design and optimization of the filter was performed using Zeland's IE3D circuit simulator. The optimized design was used to fabricate gold (Au) and High-Temperature Superconductor (HTS) versions of the fitter. We have also studied an electronically tunable version of the same filter. Tunability of the bandstop characteristics is achieved by the integration of a thin film conductor (Au or HTS) and the non-linear dielectric ferroelectric SrTiO3 in a conductor/ferroelectric/dielectric modified microstrip configuration, The performance of these filters and comparison with the simulated data will be presented. C1 Ohio Univ, Athens, OH 45701 USA. Univ Dayton, Dept Elect & Comp Engn, Dayton, OH 45469 USA. NASA, Glenn Res Ctr, Ohio Aerosp Inst Senior Res, Cleveland, OH 44135 USA. Univ Houston, Texas Ctr Superconduct, Houston, TX 77204 USA. RP Saenz, EM (reprint author), Ohio Univ, Athens, OH 45701 USA. NR 10 TC 3 Z9 3 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 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 395 EP 398 DI 10.1109/77.919366 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400085 ER PT J AU Chervenak, JA Grossman, EN Reintsema, CD Irwin, KD Moseley, SH Allen, CA AF Chervenak, JA Grossman, EN Reintsema, CD Irwin, KD Moseley, SH Allen, CA TI Sub-picowatt precision radiometry using superconducting transition edge sensor bolometers SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE blackbody; bolometer; radiometer; sub-millimeter ID ELECTROTHERMAL FEEDBACK AB We describe a cryogenic radiometric calibration system suitable for high sensitivity, low background power bolometers, The system uses a variable temperature blackbody source capable of temperatures of 4 to 20 K, whose output covers the sub-millimeter wavelength regime. The detector is an eight-channel, filled-focal-plane array of superconducting transition edge sensor (TES) bolometers, The system is designed to test components of the optical system such as polarizers, filters and stray light suppressors as well as the performance of the detector array elements, The bolometer response to incident submillimeter radiation is measured and compared to the calculated output of the source seen by the bolometer. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Inst Stand & Technol, Boulder, CO 80303 USA. RP Chervenak, JA (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. NR 5 TC 3 Z9 3 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 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 593 EP 596 DI 10.1109/77.919415 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400134 ER PT J AU Skalare, A McGrath, WR Echternach, PM LeDuc, HG Siddiqi, I Verevkin, A Prober, DE AF Skalare, A McGrath, WR Echternach, PM LeDuc, HG Siddiqi, I Verevkin, A Prober, DE TI Aluminum hot-electron bolometer mixers at submillimeter wavelengths SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE bolometer; mixer; superconductor; submillimeter; aluminum AB Diffusion-cooled aluminum hot-electron bolometer (HEB) mixers are of interest for low-noise high resolution THz-frequency spectroscopy within astrophysics, Al HEB mixers offer operation with an order of magnitude less local oscillator power, higher intermediate frequency bandwidth and potentially lower noise than competing devices made from other materials, We report on mixer experiments at 618 GHz with devices fabricated from films with sheet resistances in the range from about 55 Omega down to about 9 Omega per square. Intermediate frequency bandwidths of up to 3 GHz were measured (1 mum long device), with absorbed local oscillator power levels of 0.5 to 6 nW and mixer conversion up to -21.5 dB, High input coupling efficiency implies that the electrons in the device are able to thermalize before escaping from the device. It was found that the long coherence length complicates mixer operations due to the proximity of the contact pads, Also, saturation at the IF frequency may be a concern for this type of device, and warrants further studies. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. RI Siddiqi, Irfan/E-5548-2015 NR 12 TC 13 Z9 13 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 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 641 EP 644 DI 10.1109/77.919426 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400145 ER PT J AU Wilson, CM Frunzio, L Segall, K Li, L Prober, DE Schiminovich, D Mazin, B Martin, C Vasquez, R AF Wilson, CM Frunzio, L Segall, K Li, L Prober, DE Schiminovich, D Mazin, B Martin, C Vasquez, R TI A new noise source in superconducting tunnel junction photon detectors SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE detectors; imaging; noise; spectroscopy; superconducting devices ID X-RAY SPECTROMETERS AB We report on the development of an "all-in-one" detector that provides spectroscopy, imaging, photon timing, and high quantum efficiency with single photon sensitivity: the optical/UV single-photon imaging spectrometer using superconducting tunnel junctions. Our devices utilize a lateral trapping geometry. Photons are absorbed in a Ta thin film, creating excess quasiparticles. Quasiparticles diffuse and are trapped by Al/AlOx/Al tunnel junctions located on the sides of the absorber. Imaging devices have tunnel junctions on two opposite sides of the absorber. Position information is obtained from the fraction of the total charge collected by each junction. We have measured the single photon response of our devices. For photon energies between 2 eV and 5 eV we measure an energy resolution between 0.47 eV and 0.40 eV respectively on a selected region of the absorber. We see evidence that thermodynamic fluctuations of the number of thermal quasiparticles in the junction electrodes leads to current noise that far exceeds the expected shot noise of the de bias current, We believe that this may limit the resolution of our present generation of detectors at the operating temperature of 0.22 K. C1 Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. CALTECH, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wilson, CM (reprint author), Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. RI Wilson, Christopher/A-9676-2008; Mazin, Ben/B-8704-2011; OI Mazin, Ben/0000-0003-0526-1114; Frunzio, Luigi/0000-0002-0272-5481 NR 14 TC 11 Z9 11 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 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 645 EP 648 DI 10.1109/77.919427 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400146 ER PT J AU Li, L Frunzio, L Wilson, C Segall, K Prober, DE Szymkowiak, AE Moseley, SH AF Li, L Frunzio, L Wilson, C Segall, K Prober, DE Szymkowiak, AE Moseley, SH TI X-ray single photon 1-D imaging spectrometers SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE imaging; single photon; spectrometer; superconducting tunnel junction; x-ray detector ID TUNNEL-JUNCTION DETECTORS; RESOLUTION; ENERGY; NOISE AB We have developed superconducting single-photon 1-D imaging x-ray detectors with an energy resolution of 13 eV FWHM at 6 keV and 1-D spatial resolution of 0.25 mum over a length of 20 mum in an effective area of 20 x 100 mum(2). The energy resolution along the 200 mum long absorber is 36 eV. The energy resolution of 13 eV is among the best reported for this kind of detectors and is within factor of 2 of its theoretical limit. The signals are read out by low-noise current amplifier with ii de voltage bias. The electronic noise measured by injecting pulses is 8 eV FWHM at 6 keV. By cooling the feedback resistor the current noise is reduced from 160 fA/Hz(1/2) to 90 fA/Hz(1/2). C1 Yale Univ, Dept Phys & Appl Phys, New Haven, CT 06520 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Li, L (reprint author), Yale Univ, Dept Phys & Appl Phys, New Haven, CT 06520 USA. OI Frunzio, Luigi/0000-0002-0272-5481 NR 12 TC 10 Z9 10 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 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 685 EP 687 DI 10.1109/77.919437 PN 1 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400156 ER PT J AU Stevenson, TR Aassime, A Delsing, P Schoelkopf, R Segall, K Stahle, CM AF Stevenson, TR Aassime, A Delsing, P Schoelkopf, R Segall, K Stahle, CM TI RF single electron transistor readout amplifiers for superconducting astronomical detectors of X-ray to sub-mm wavelengths SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE amplifiers; feedback; multiplexing; photodetectors; tunneling ID TUNNEL-JUNCTIONS; JOSEPHSON; SQUIDS AB We have made Radio-Frequency Single-Electron Transistors (RF-SETs) with large input gates, and tested performance and modes of operation with the goal of using such devices as on-chip amplifiers for a variety of high impedance cryogenic photodetectors. We achieved approximate to 100 kHz of closed-loop bandwidth for charge-locked-loop and transimpedance amplifier feedback configurations, and have combined amplifier outputs using a form of wavelength division multiplexing. With our choice of SET junction resistance, a 0.5 fF input gate capacitance gave a cotunneling-degraded charge noise of 1x10(-4) e/root Hz, but a fairly low input voltage noise of 30 nV/root Hz. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Orbital Sci Corp, Dulles, VA 20166 USA. Chalmers Univ Technol, Gothenburg, Sweden. Dept Microelect & Nanosci, S-41296 Gothenburg, Sweden. Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. RP Stevenson, TR (reprint author), NASA, Goddard Space Flight Ctr, Code 553, Greenbelt, MD 20771 USA. RI Delsing, Per/F-7288-2010; Schoelkopf, Robert/J-8178-2012 OI Delsing, Per/0000-0002-1222-3506; NR 16 TC 10 Z9 10 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 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 692 EP 695 DI 10.1109/77.919439 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400158 ER PT J AU Tralshawala, N Brekosky, RP Li, MJ Figueroa-Feliciano, E Finkbeiner, FM Lindeman, MA Stahle, CM Stahle, CK AF Tralshawala, N Brekosky, RP Li, MJ Figueroa-Feliciano, E Finkbeiner, FM Lindeman, MA Stahle, CM Stahle, CK TI Fabrication of Mo/Au transition-edge sensors for x-ray spectrometry SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE superconducting transition edge sensors; microcalorimeter; proximity effect ID RESOLUTION AB We present fabrication details of our Mo/Au x-ray microcalorimeters, which are being developed as one of the candidate high resolution spectrometers for the Constellation-X mission. We have reproducibly fabricated Mo/Au transition-edge sensors with Tc's of similar to 100 mK on etched silicon nitride membranes and connected via superconducting Nb leads. Our single pixel devices have, so far, attained resolution of 3.7 eV at 3.3 keV, We also discuss our plans for fabrication and testing of fully functional multi-pixel array of x-ray microealorimeters. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Raytheon ITSS Corp, Lanham, MD USA. Swales Aerosp Corp, Beltsville, MD USA. Stanford Univ, Dept Phys, Stanford, CA 94305 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Tralshawala, N (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 11 TC 14 Z9 15 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 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 755 EP 758 DI 10.1109/77.919455 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400174 ER PT J AU Mansour, RR Romano, T Ye, S Peik, S Nast, T Enlow, D Wilker, C Warner, J AF Mansour, RR Romano, T Ye, S Peik, S Nast, T Enlow, D Wilker, C Warner, J TI Development of space qualifiable HTS communication subsystems SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE superconductive filters; cryogenic receivers communication systems ID MULTIPLEXERS AB The paper presents the measured results of a C-band 60-channel superconductive input multiplexer integrated with pulse tube space-qualified cryocoolers. The multiplexer is developed to duplicate the requirements of the INTELSAT 8 program. The channel filters are self-equalized Ill-pole HTS planar structures designed with drop-in cryogenic ferrite circulators and isolators. The paper presents details on RF design, packaging and cryocooler integration. It demonstrates that at least 50 % reduction in mass and 50 % reduction in size can be achieved by replacing the INTELSAT 8 C-band dielectric resonator input multiplexer with a superconductive multiplexer. C1 Lockheed Martin, Bethesda, MD 20817 USA. Dupont, Wilmington, DE USA. NASA, Glenn Res Ctr, Washington, DC 20546 USA. NR 6 TC 3 Z9 5 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 806 EP 811 DI 10.1109/77.919467 PN 1 PG 6 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400186 ER PT J AU Kawamura, J Tong, CYE Blundell, R Papa, DC Hunter, TR Patt, F Gol'tsman, G Gershenzon, E AF Kawamura, J Tong, CYE Blundell, R Papa, DC Hunter, TR Patt, F Gol'tsman, G Gershenzon, E TI Terahertz-frequency waveguide NbN hot-electron bolometer mixer SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE superconducting receiver; hot-electron bolometer mixer; terahertz techniques ID RECEIVER; OPERATION; THZ AB We have developed a low-noise waveguide heterodyne receiver for operation near 1 THz using phonon-cooled NbN hot-electron boiometers, The mixer elements are submicron-sized microbridges of 4 nm-thick NbN film fabricated on a quartz substrate. Operating at a bath temperature of 4.2 K, the double-sideband receiver noise temperature is 760 K at 1.02 THz and 1100 K at 1.26 THz, The local oscillator is provided by solid-state sources, and power measured at the source is less than 1 muW The intermediate frequency bandwidth exceeds 2 GHz, The receiver was used to make the first ground-based heterodyne detection of a celestial spectroscopic line above 1 THz. C1 CALTECH, Pasadena, CA 91125 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Submillimeter Telescope Observ, Tucson, AZ 85721 USA. Moscow State Pedag Univ, Moscow 119435, Russia. RP Kawamura, J (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. OI Tong, Edward/0000-0002-7736-4203; Hunter, Todd/0000-0001-6492-0090 NR 10 TC 16 Z9 17 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 952 EP 954 DI 10.1109/77.919505 PN 1 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400222 ER PT J AU Siddiqi, I Verevkin, A Prober, DE Skalare, A Karasik, BS McGrath, WR Echternach, P LeDuc, HG AF Siddiqi, I Verevkin, A Prober, DE Skalare, A Karasik, BS McGrath, WR Echternach, P LeDuc, HG TI Noise and conversion efficiency of aluminum superconducting hot-electron bolometer mixer SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE hot-electron bolometer; mixer; terahertz spectroscopy ID IN-DIFFUSION AB We report on microwave measurements of superconducting aluminum hot-electron bolometers (Al HEBs), Diffusion-cooled Al HEB mixers are good candidates for space-borne applications in the Terahertz frequency range since they are predicted to have small local oscillator (LO) power requirements, intermediate frequency (IF) bandwidths greater than or similar to 10 GHz, and a noise temperature lower than that of Nb and NbN HEB mixers. Mixer measurements were made at an LO frequency similar to 30 GHz, with an IF in the range 0.1 to 7.3 GHz, For T < 0.8 K, a magnetic field H=0.1-0.3T was applied to suppress the superconductivity in the contact pads, and partly in the bridge. For a 0.6 mum long device, we measure an IF bandwidth of 4 GHz, a conversion efficiency eta = -8dB, and a mixer noise temperature T-M greater than or similar to 4K, DSB (T-mixer=T-output noise/2 eta). These results are shown to be in quantitative agreement with simple theoretical predictions. C1 Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. NASA, Jet Prop Lab, Pasadena, CA 91109 USA. RP Siddiqi, I (reprint author), Yale Univ, Dept Appl Phys, New Haven, CT 06520 USA. RI Siddiqi, Irfan/E-5548-2015 NR 14 TC 7 Z9 7 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 958 EP 961 DI 10.1109/77.919507 PN 1 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400224 ER PT J AU Kleinsasser, AW AF Kleinsasser, AW TI High performance Nb Josephson devices for petaflops computing SO IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY LA English DT Article; Proceedings Paper CT 2000 Applied Superconductivity Conference CY SEP 17-22, 2000 CL VIRGINIA BEACH, VIRGINIA DE superconducting devices; Josephson junctions; cryogenic electronics ID INTEGRATED-CIRCUITS; TUNNEL-JUNCTIONS; TEMPERATURE AB The Hybrid Technology Multi-Threaded (HTMT) approach to petaflops computing includes large numbers of ultra-high performance Nb Rapid Single Flux Quantum IRSFQ) processor and memory chips, making it by far the largest active superconducting electronics project in the United States. In order to achieve petaflops, RSFQ circuits with 10(5) to 10(6) junctions per chip will be required to operate at clock speeds of 50 to 100 GHz, far beyond the current state of the art. In this paper, we review the state of the art of Nh circuit fabrication and discuss the requirements for significantly improving circuit density and speed. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kleinsasser, AW (reprint author), CALTECH, Jet Prop Lab, M-S 302-231, Pasadena, CA 91109 USA. NR 22 TC 16 Z9 17 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 1051-8223 J9 IEEE T APPL SUPERCON JI IEEE Trans. Appl. Supercond. PD MAR PY 2001 VL 11 IS 1 BP 1043 EP 1049 DI 10.1109/77.919527 PN 1 PG 7 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA 425HP UT WOS:000168285400244 ER PT J AU Wang, JR Racette, PE Triesky, ME AF Wang, JR Racette, PE Triesky, ME TI Retrieval of precipitable water vapor by the millimeter-wave imaging radiometer in the arctic region during FIRE-ACE SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID CLOUD; MODEL AB Millimeter-wave radiometric measurements obtained from the NASA ER-2 aircraft over the arctic region on May 20, 1998, were used to estimate precipitable water (PW) in the range less than or equal to 0.60 g/cm(2). The approach is a modified version of the recent work by Miao [1], which utilized the radiometric measurements at 150, 183.3 +/- 3, and 183.3 +/- 7 GHz of the SSM/T-2 sensor to retrieve PW over the antarctic region. However, Miao has implicitly assumed a surface emissivity that is frequency independent over the 150-183 GHz range, This assumption turns out not to be a good one based on the airborne measurements described below and the errors introduced in the PW estimation were substantial in many cases. It is shown below that four-frequency radiometric measurements in the frequency range of 150-220 GHz provided a robust retrieval of PW, while allowing for a surface emissivity that varied linearly with frequency, The retrieved PW compared favorably with that calculated from rawinsonde data at two widely separated locations, The differences between the retrieved and calculated values are not more than +/-0.02 g/cm(2), which is smaller than errors associated with measurement uncertainty. It is found necessary to account for the double side-band nature of the 183.3 GHz measurements in the raditive transfer calculations for development of the retrieval algorithm, The PW values estimated from the algorithm developed from single side band, 183.3 GHz radiative transfer calculations could be in error by as much as +/-0.10 g/cm(2). Finally, the effect of surface temperature variations is shown to introduce only a small error in the estimation of PW. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Wang, JR (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. NR 14 TC 17 Z9 17 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 2001 VL 39 IS 3 BP 595 EP 605 DI 10.1109/36.911117 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 413TM UT WOS:000167628100012 ER PT J AU Piepmeier, JR Gasiewski, AJ AF Piepmeier, JR Gasiewski, AJ TI High-resolution passive polarimetric microwave mapping of ocean surface wind vector fields SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID AIRCRAFT K-BAND; BRIGHTNESS TEMPERATURES; SCATTEROMETER DATA; MODEL; RADIOMETERS; WATER; SPEED; SSM/I AB The retrieval of ocean surface wind fields in both one and two dimensions is demonstrated using passive polarimetric microwave imagery obtained from a conical-scanning airborne polarimeter. The retrieval method is based on an empirical geophysical model function (GMF) for ocean surface thermal emission and an adaptive maximum likelihood (ML) wind vector estimator, Data for the GMF were obtained using the polarimetric scanning radiometer/digital (PSR/D) on the NASA P-3 aircraft during the Labrador Sea Deep Convection Experiment in 1997, To develop the GMF, a number of buoy overflights and GPS dropsondes were used, out of which a GMF of 10.7, 18.7, and 37.0 GHz azimuthal harmonics for the first three Stokes parameters was constructed for the SSM/I incident angle of 53.1 degrees. The data show repeatable azimuthal harmonic coefficient amplitudes of similar to2-3 K peak-to-peak, with a 100% increase in harmonic amplitudes as the frequency is increased from 10.7 to 37 GHz. The GMF is consistent with and extends the results of two independent studies of SSM/I data and also provides a model for the third Stokes parameter over wind speeds up to 20 m/s, The aircraft data show that the polarimetric channels are much less susceptible to geophysical noise associated with maritime convection than the first two Stokes parameters. The polarimetric measurement technique used in the PSR/D also demonstrates the viability of digital correlation radiometry for aircraft or satellite measurements of the full Stokes vector. The ML retrieval algorithm incorporates the additional information on wind direction available from multiple looks and polarimetric channels in a straightforward manner and accommodates the reduced SNRs of the first two Stokes parameters in the presence of convection by weighting these channels by their inverse SNR. The Cramer-Rao bound for the retrieval operator is computed using the SNR estimates. Here, the measurement noise is a root-sum-squared combination of both instrument (radiometric) noise and geophysical (cloud and convection) noise. The retrieved wind directions are within 9 degrees of GPS-dropsonde wind-direction measurements, and the standard deviations are similar to2 times the Cramer-Rao bound. The retrieval method illustrates the capability of mapping ocean surface wind fields from either airborne or spaceborne platforms using a two-look technique. C1 Georgia Inst Technol, Sch Elect & Comp Engn, Atlanta, GA 30332 USA. NOAA, Environm Technol Lab, Boulder, CO 80303 USA. RP Piepmeier, JR (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 36 TC 80 Z9 93 U1 1 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 2001 VL 39 IS 3 BP 606 EP 622 DI 10.1109/36.911118 PG 17 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 413TM UT WOS:000167628100013 ER PT J AU Stough, TM Brodley, CE AF Stough, TM Brodley, CE TI Focusing attention on objects of interest using multiple matched filters SO IEEE TRANSACTIONS ON IMAGE PROCESSING LA English DT Article DE feature selection; focus of attention; image database search; k-means; multiple matched filters AB In order to be of use to scientists, large image databases need to be analyzed to create a catalog of the objects of interest. One approach is to apply a multiple tiered search algorithm that uses reduction techniques of increasing computational complexity to select the desired objects from the database. The first tier of this type of algorithm, often called a focus of attention (FOA) algorithm, selects candidate regions from the image data and passes them to the next tier of the algorithm, In this paper we present a new approach to FOA that employs multiple matched filters (MMF), one for each object prototype, to detect the regions of interest. The MMFs are formed using K-means clustering on a set of image patches identified by domain experts as positive examples of objects of interest. An innovation of the approach is to radically reduce the dimensionality of the feature space, used by the k-means algorithm, by taking block averages (spoiling) the sample image patches. The process of spoiling is analyzed and its applicability to other domains is discussed. Combination of the output of the MMFs is achieved through the projection of the detections back into an empty image and then thresholding, This research was motivated by the need to detect small volcanos in the Magellan probe data from Venus. An empirical evaluation of the approach illustrates that a combination of the MMF plus the average filter results in a higher likelihood of 100% detection of the objects of interest at a lower false positive rate than a single matched filter alone. C1 Purdue Univ, Sch Elect & Comp Engn, W Lafayette, IN 47906 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Stough, TM (reprint author), Purdue Univ, Sch Elect & Comp Engn, W Lafayette, IN 47906 USA. NR 11 TC 9 Z9 9 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 1057-7149 J9 IEEE T IMAGE PROCESS JI IEEE Trans. Image Process. PD MAR PY 2001 VL 10 IS 3 BP 419 EP 426 DI 10.1109/83.908516 PG 8 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 409QK UT WOS:000167394200007 PM 18249631 ER PT J AU Rubaai, A Ricketts, D Kankam, MD AF Rubaai, A Ricketts, D Kankam, MD TI Experimental verification of a hybrid fuzzy control strategy for a high-performance brushless DC drive system SO IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS LA English DT Article; Proceedings Paper CT Annual Meeting of the Industry-Applications-Society CY OCT 03-07, 1999 CL PHOENIX, ARIZONA SP Ind Applicat Soc DE brushless drives; hybrid fuzzy control; proportional-integral controller; switching strategy; unknown environment ID LOGIC CONTROLLER; MOTOR DRIVE; DESIGN; SPEED AB This paper describes the design and experimental verification of a hybrid fuzzy control system for a high-performance brushless de motor drive. Both the design of the fuzzy controller and its integration with the proportional-integral (PI) in a global control system are discussed. The principle of the proposed control system is to use a PI controller, which performs satisfactorily in most cases, while keeping in the background, a fuzzy controller, which is ready to take over the PI controller when severe perturbations occur. Strategies of the switching control for the hybrid controller is such that the fuzzy controller is activated whenever the resident system exhibits an oscillatory and/or overshoot behavior. Thus, the PI and fuzzy controllers can be managed to take advantage of their positive attributes. Performance of the hybrid fuzzy-PI controller is evaluated through a laboratory implementation. The laboratory implementation is based on a linguistic fuzzy controller whose design is derived from the expert knowledge gained during disturbances. Experimental results have shown excellent tracking performance of the proposed control system, and have convincingly demonstrated the usefulness of the hybrid fuzzy controller in high-performance drives with uncertainties. C1 Howard Univ, Dept Elect Engn, Washington, DC 20059 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Rubaai, A (reprint author), Howard Univ, Dept Elect Engn, Washington, DC 20059 USA. NR 19 TC 34 Z9 37 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 0093-9994 J9 IEEE T IND APPL JI IEEE Trans. Ind. Appl. PD MAR-APR PY 2001 VL 37 IS 2 BP 503 EP 512 DI 10.1109/28.913715 PG 10 WC Engineering, Multidisciplinary; Engineering, Electrical & Electronic SC Engineering GA 417EP UT WOS:000167822700015 ER PT J AU Simon, MK Alouini, MS AF Simon, MK Alouini, MS TI Simplified noisy reference loss evaluation for digital communication in the presence of slow fading and carrier phase error SO IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY LA English DT Article DE carrier synchronization; digital communicating; fading channels; noisy reference loss ID PERFORMANCE AB Using a Maclaurin series expansion of the conditional ton the carrier phase error) bit error probability of binary and quaternary phase-shift keying (BPSK and QPSK, respectively) and then averaging this result over both the statistics of the carrier phase error and the channel fading, closed-form expressions for the average bit error probability are derived in a form that lend themselves toward obtaining simple formulas for the associated noisy reference loss. Numerical evaluation of this loss based on the use of these formulas is shown to provide excellent accuracy when compared with the exact evaluation, which requires two-fold numerical integration. Although the method is specifically applied to BPSK and QPSK, it is easily extended to other forms of modulation whose conditional bit error probability is known in closed form. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Minnesota, Minneapolis, MN 55455 USA. RP Simon, MK (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 15 Z9 16 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9545 J9 IEEE T VEH TECHNOL JI IEEE Trans. Veh. Technol. PD MAR PY 2001 VL 50 IS 2 BP 480 EP 486 DI 10.1109/25.923059 PG 7 WC Engineering, Electrical & Electronic; Telecommunications; Transportation Science & Technology SC Engineering; Telecommunications; Transportation GA 433ZQ UT WOS:000168791000013 ER PT J AU Jessup, JM Pellis, NR AF Jessup, JM Pellis, NR TI NASA biotechnology: Cell science in microgravity SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Editorial Material ID SIMULATED MICROGRAVITY; DIFFERENTIATION; CULTURE C1 Univ Texas, Hlth Sci Ctr, San Antonio, TX 78284 USA. NASA, Lyndon B Johnson Space Ctr, Cellular Biotechnol Program, Houston, TX 77058 USA. RP Jessup, JM (reprint author), Univ Texas, Hlth Sci Ctr, 7703 Floyd Curl Dr, San Antonio, TX 78284 USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU SOC IN VITRO BIOLOGY PI LARGO PA 9315 LARGO DR WEST, STE 25, LARGO, MD 20774 USA SN 1071-2690 J9 IN VITRO CELL DEV-AN JI In Vitro Cell. Dev. Biol.-Anim. PD MAR PY 2001 VL 37 IS 3 BP U2 EP U3 PG 2 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 432KN UT WOS:000168690900001 ER PT J AU Killingsworth, BL Hayden, MB Crawford, D Schellenberger, R AF Killingsworth, BL Hayden, MB Crawford, D Schellenberger, R TI A model for motivating and measuring quality performance in information systems staff SO INFORMATION SYSTEMS MANAGEMENT LA English DT Article ID MANAGEMENT AB This article presents a model developed to motivate and measure quality performance in information systems staff. This approach, referred to as team-based assessment (TBA), is founded on organizational effectiveness and quality principles. The team-based assessment approach emphasizes two main goals - to maintain a customer orientation and to promote an atmosphere for employee development and growth - while ensuring individual and team accountability. To assess the achievement of these goals, a formal system of measurements has been developed. The approach encompasses five critical areas: product quality, staff development, customer outreach, administrative efficiency, and fiscal responsibility. This model is currently in use at several large government contract-based organizations. C1 E Carolina Univ, Greenville, NC 27858 USA. Rhode Isl Coll, Providence, RI 02908 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Killingsworth, BL (reprint author), E Carolina Univ, Greenville, NC 27858 USA. NR 9 TC 4 Z9 4 U1 0 U2 3 PU AUERBACH PUBLICATIONS PI BOCA RATON PA C/O CRC PRESS L L C, 2000 CORPORATE BLVD NW, BOCA RATON, FL 33431 USA SN 1058-0530 J9 INFORM SYST MANAGE JI Inf. Syst. Manage. PD SPR PY 2001 VL 18 IS 2 BP 8 EP 14 PG 7 WC Computer Science, Information Systems SC Computer Science GA 407WG UT WOS:000167293300001 ER PT J AU Raj, SV Locci, IE AF Raj, SV Locci, IE TI Microstructural characterization of a directionally-solidified Ni-33 (at.%) Al-31Cr-3Mo eutectic alloy as a function of withdrawal rate SO INTERMETALLICS LA English DT Article DE nickel aluminides, based on NiAl; crystal growth; microstructure; microscopy, various; aero-engine components ID ROD-PLATE TRANSITION; NIAL-CR; CREEP-BEHAVIOR; COMPOSITES; LAMELLAR; GROWTH AB The Ni-33 (at.%)Al-31Cr-3Mo eutectic alloy was directionally-solidified (DS) at different rates, V-1, varying between 2.5 to 508 mm h(-1). Detailed qualitative and quantitative metallographic and chemical analyses were conducted on the directionally-solidified rods. The microstructures consisted of eutectic colonies with parallel lamellar NiAl/(Cr.Mo) plates for solidification rates at and below 12.7 mm h(-1). Cellular eutectic microstructures were observed at higher solidification rates, where the plates exhibited a radial pattern. The microstructures were demonstrated to be fairly uniform throughout a 100 mm length of the DS zone by quantitative metallography. The average cell size, d, decreased with increasing growth rate to a value of 125 mum ar 508 mm h(-1) according to the relation d (mum) approximate to 465 V-1(-0.22). where V-1 is in mm h(-1). Both the average NiAl plate thickness. <()over bar>(NiAl), and the interlamellar spacing, <()over bar>. were observed to be constant for V-1 less than or equal to 50.8 mm h(-1) but decreased with increasing growth rate above this value as <()over bar>(NiAl) (m)= 61.2 V-1(-0.93) and <()over bar> (mum) == 47.7 V-1(-0.64), respectively. The present results are detailed on a microstructural map. Published by Elsevier Science Ltd. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Raj, SV (reprint author), NASA, Glenn Res Ctr, MS 24-1,21000 Brookpk Rd, Cleveland, OH 44135 USA. EM sai.v.raj@grc.nasa.gov NR 21 TC 37 Z9 40 U1 2 U2 5 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0966-9795 EI 1879-0216 J9 INTERMETALLICS JI Intermetallics PD MAR PY 2001 VL 9 IS 3 BP 217 EP 227 DI 10.1016/S0966-9795(00)00128-X PG 11 WC Chemistry, Physical; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Chemistry; Materials Science; Metallurgy & Metallurgical Engineering GA 413QF UT WOS:000167622700005 ER PT J AU Joshi, SM Kelkar, AG AF Joshi, SM Kelkar, AG TI Passivity-based robust control of systems with redundant sensors and actuators SO INTERNATIONAL JOURNAL OF CONTROL LA English DT Article AB This paper considers passivity-based control of a class of uncertain linear, time-invariant systems having redundant sensors and actuators. The approach consists of robustly 'passifying' (i.e. rendering passive) the system, which is assumed to have affine parametric uncertainties in the system matrix as well as the input and output matrices. The passification is accomplished by finding constant matrices to be placed at the input and out put of the system which will appropriately combine the sensor signals and distribute the control signals to the actuators. Sufficient conditions are first obtained for the system to remain passive for all parameter values that lie in a hyper-rectangular region in the parameter space. The conditions take the form of a set of linear matrix inequalities (LMIs). Next, the problem of finding an optimal sensor blending matrix is considered, which will maximize the region in the parameter space in which the system remains robustly passive. The dual problem of optimal control allocation is also considered, and a method is given for combined sensor blending and control allocation for robust passification. A method for reduction of the number of LMIs is investigated, and a numerical example is given for demonstrating the approach. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Kansas State Univ, Dept Mech Engn, Manhattan, KS 66506 USA. RP Joshi, SM (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 10 TC 6 Z9 6 U1 1 U2 4 PU TAYLOR & FRANCIS LTD PI LONDON PA 11 NEW FETTER LANE, LONDON EC4P 4EE, ENGLAND SN 0020-7179 J9 INT J CONTROL JI Int. J. Control PD MAR PY 2001 VL 74 IS 5 BP 474 EP 481 DI 10.1080/00207170010010588 PG 8 WC Automation & Control Systems SC Automation & Control Systems GA 408GJ UT WOS:000167317900006 ER PT J AU Rashidnia, N Balasubramaniam, R Kuang, J Petitjeans, P Maxworthy, T AF Rashidnia, N Balasubramaniam, R Kuang, J Petitjeans, P Maxworthy, T TI Measurement of the diffusion coefficient of miscible fluids using both interferometry and Wiener's method SO INTERNATIONAL JOURNAL OF THERMOPHYSICS LA English DT Article; Proceedings Paper CT 14th Symposium on Thermophysical Properties CY JUN 25-30, 2000 CL UNIV COLORADO, BOULDER, COLORADO SP Natl Inst Stand & Technol, Amer Soc Mech Engineers, Comm Thermophys Properties Heat Transfer Div, Phys & Chem Properties Div, Chem Sci & Technol Lab HO UNIV COLORADO DE diffusion coefficient; interferometry; miscible interfaces; Wiener's method AB Measurements of the diffusion coefficient of two miscible liquids are reported. The liquids at e various combinations of pure silicone oils and those to which small amounts of solvents are added to control the difference in density between the fluids. The liquids were placed in a quartz cell such that the interface is initially horizontal. As the fluids diffuse, the profile of the index of refraction near the interface is time dependent and is related to the local concentration of the diffusing fluids. The concentration gradient profile was measured by a shearing interferometer incorporating a Wollaston prism, as well as Wiener`s method. In the latter technique, a 45 degrees light sheet was passed through the test cell. and the local deflection of the light beam was measured. The average diffusion coefficient was obtained by analysis of the measured concentration gradient profile, assuming that the diffusion process is one-dimensional and is characterized by a constant value of the diffusion coefficient. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. Univ So Calif, Dept Aerosp & Mech Engn, Los Angeles, CA 90089 USA. ESPCI, PMMH, F-90075 Paris, France. RP Balasubramaniam, R (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, 21000 Brookpk Rd,Mail Stop 110-3, Cleveland, OH 44135 USA. NR 8 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 0195-928X J9 INT J THERMOPHYS JI Int. J. Thermophys. PD MAR PY 2001 VL 22 IS 2 BP 547 EP 555 DI 10.1023/A:1010735117408 PG 9 WC Thermodynamics; Chemistry, Physical; Mechanics; Physics, Applied SC Thermodynamics; Chemistry; Mechanics; Physics GA 435EN UT WOS:000168864600017 ER PT J AU Tin, P Frate, D de Groh, HC AF Tin, P Frate, D de Groh, HC TI Determination of surface tension of succinonitrile using a surface light scattering spectrometer SO INTERNATIONAL JOURNAL OF THERMOPHYSICS LA English DT Article; Proceedings Paper CT 14th Symposium on Thermophysical Properties CY JUN 25-30, 2000 CL UNIV COLORADO, BOULDER, COLORADO SP Natl Inst Stand & Technol, Amer Soc Mech Engineers, Comm Thermophys Properties Heat Transfer Div, Phys & Chem Properties Div, Chem Sci & Technol Lab HO UNIV COLORADO DE succinonitrile; surface light scattering spectroscopy; surface tension ID SPECTROSCOPY AB Liquid/vapor interfacial surface tensions of succinonitrile, NC(CH2)(2)CN, were measured using noninvasive surface light scattering (SLS) spectroscopy. Succinonitrile (SCN) has been and is being used extensively in materials science and fluid physics research, for example. in several theoretical and numerical studies of dendritic growth. It is an established model material with several essential physical properties accurately known with the exception of the liquid/vapor surface tension, y(1v), at various temperatures. Using the SLS spectrometer, we have experimentally determined the liquid/vapor surface tension of SCN in the temperature range from just above its melting point (58.1 degreesC) to 118 degreesC using this noninvasive method. Previous measurements of SCN surface tension are extremely limited. To the best of our knowledge, this work is the first to measure the surface tension of succinonitrile noninvasively at melt and elevated temperatures. The SLS spectroscopy is relatively new and unique. This technique has several advantages over classical methods: it is noninvasive, has a good accuracy, and can be used to measure the surface tension and viscosity simultaneously, although the viscosity results are not discussed here. The accuracy of values obtained from this technique on some standard liquids is better than 2% for the surface tension and about 10 to 15% for viscosity. Our measurements gave y(1v) = 42.28 - 0.0629T +/- 0.2 (mN (.) m(-1)), with T in degreesC, and the viscosity at 60 degreesC is 2.68 +/- 0.3 cp for pure SCN. C1 NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. NASA, Glenn Res Ctr, Micrograv Sci Div, Cleveland, OH 44135 USA. NASA, Glenn Res Ctr, Div Mat, Cleveland, OH 44135 USA. RP Tin, P (reprint author), NASA, Glenn Res Ctr, Natl Ctr Micrograv Res Fluids & Combust, Cleveland, OH 44135 USA. NR 21 TC 4 Z9 4 U1 1 U2 2 PU KLUWER ACADEMIC/PLENUM PUBL PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0195-928X J9 INT J THERMOPHYS JI Int. J. Thermophys. PD MAR PY 2001 VL 22 IS 2 BP 557 EP 568 DI 10.1023/A:1010787201479 PG 12 WC Thermodynamics; Chemistry, Physical; Mechanics; Physics, Applied SC Thermodynamics; Chemistry; Mechanics; Physics GA 435EN UT WOS:000168864600018 ER PT J AU Deshmukh, A Middelkoop, T Krothapalli, A Shields, W Chandra, N Smith, CA AF Deshmukh, A Middelkoop, T Krothapalli, A Shields, W Chandra, N Smith, CA TI Multiagent design architecture for intelligent synthesis environment SO JOURNAL OF AIRCRAFT LA English DT Article AB The intelligent synthesis environment (ISE) represents the integration of a broad range of high-fidelity knowledge at the design stage to facilitate the product realization process. ISE has the potential of reducing the product realization time by several orders of magnitude. The key characteristics of ISE are integrated evaluation of product life-cycle stages in a virtual environment, coordination of asynchronous design activities, design configuration selection based on multiple design criteria, and interoperability among heterogeneous software and hardware environments to accomplish an effective collaborative computational system. Multiagent design architecture (MADA) is designed to provide a flexible integration framework for ISE. This architecture provides seamless integration of product realization activities across heterogeneous machines, computing platforms, programming languages, data, and process representations using distributed intelligent agents. An agent in the context of MADA is an autonomous computational entity that is capable of migrating across computing environments asynchronously. These agents have intelligence in the form of individual goals, beliefs, learning mechanisms and interact cooperatively to accomplish overall product design objectives. An application of the MADA information framework for the design of aerospace components is presented. Specifically, the use of integrated design and analysis tools for creating a high-speed civil transport exhaust nozzle is demonstrated. C1 Univ Massachusetts, Dept Mech & Ind Engn, Amherst, MA 01003 USA. Florida State Univ, Tallahassee, FL 32310 USA. NASA, George C Marshall Space Flight Ctr, Generat Reusable Launch Vehicle Program 2, Huntsville, AL 35812 USA. RP Deshmukh, A (reprint author), Univ Massachusetts, Dept Mech & Ind Engn, Amherst, MA 01003 USA. NR 17 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAR-APR PY 2001 VL 38 IS 2 BP 215 EP 223 DI 10.2514/2.2778 PG 9 WC Engineering, Aerospace SC Engineering GA 420KR UT WOS:000168004600003 ER PT J AU Palumbo, D Cabell, R Sullivan, B Cline, J AF Palumbo, D Cabell, R Sullivan, B Cline, J TI Flight test of active structural acoustic noise control system SO JOURNAL OF AIRCRAFT LA English DT Article ID VIBRATION; REDUCTION; CABIN; SOUND AB A flight test is described in which an active structural/acoustic control system reduces turboprop induced interior noise on a Raytheon Aircraft Company 1900D airliner. Control inputs to 21 inertial force actuators were computed adaptively using a principal component domain version of the multichannel filtered-x least mean square algorithm to minimize the mean square response of 32 microphones. A tabu search algorithm was employed to optimize placement of the force actuators on the aircraft frame. Both single-frequency and multifrequency control results are presented. Noise reductions of up to 15 dB were obtained at the blade passage frequency (BPF) during single-frequency control tests. Simultaneous noise reductions of 10 dB, 2.5 dB, and 3.0 dB, at the BPF and next 2 harmonics, were obtained in a multifrequency test. C1 NASA, Langley Res Ctr, Struct Acoust Branch, Hampton, VA 23681 USA. USA, Res Lab, Struct Mech Div, Hampton, VA 23681 USA. RP Palumbo, D (reprint author), NASA, Langley Res Ctr, Struct Acoust Branch, Hampton, VA 23681 USA. NR 15 TC 4 Z9 5 U1 1 U2 7 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 MAR-APR PY 2001 VL 38 IS 2 BP 277 EP 284 DI 10.2514/2.2760 PG 8 WC Engineering, Aerospace SC Engineering GA 420KR UT WOS:000168004600011 ER PT J AU Carr, LW Chandrasekhara, MS Wilder, MC Noonan, KW AF Carr, LW Chandrasekhara, MS Wilder, MC Noonan, KW TI Effect of compressibility on suppression of dynamic stall using a slotted airfoil SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT 36th AIAA Aerospace Sciences Meeting and Exhibit CY JAN 12-15, 1998 CL RENO, NEVADA AB A multielement airfoil designed for helicopter application has been tested for compressible dynamic stall behavior and has been proven to he a robust dynamic stall-free concept. This slotted airfoil has operated into poststall areas without the dynamic stall vortex that is normally present whenever airfoils are tested beyond their static stall boundary. Point diffraction interferogram images of the dynamic flow over the airfoil are presented, showing details of the flow development during the oscillation cycle, and instantaneous pressure distributions on the airfoil and slat during dynamic airfoil motion are included. C1 NASA, Ames Res Ctr, Aeroflightdynam Directorate, USA Aviat & Missile Command, Moffett Field, CA 94035 USA. USN, Postgrad Sch, NASA, Joint Inst Aeronaut,Dept Aeronaut & Astronaut, Monterey, CA 93943 USA. Eloret, Sunnyvale, CA USA. NASA, Langley Res Ctr, Aeroflightdynam Directorate, USA Aviat & Missile Command, Hampton, VA 23681 USA. RP Carr, LW (reprint author), NASA, Ames Res Ctr, Aeroflightdynam Directorate, USA Aviat & Missile Command, Moffett Field, CA 94035 USA. NR 12 TC 8 Z9 8 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 MAR-APR PY 2001 VL 38 IS 2 BP 296 EP 309 DI 10.2514/2.2762 PG 14 WC Engineering, Aerospace SC Engineering GA 420KR UT WOS:000168004600013 ER PT J AU Park, O Haftka, RT Sankar, VB Starnes, JH Nagendra, S AF Park, O Haftka, RT Sankar, VB Starnes, JH Nagendra, S TI Analytical-experimental correlation for a stiffened composite panel loaded in axial compression SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT 39th AIAA/ASME/ASCE/AHS/ASC Conference on Structures Strucural Dynamics and Materials CY APR 20-23, 1998 CL LONG BEACH, CALIFORNIA ID MINIMUM-WEIGHT DESIGN; PANDA2; HOLE AB A combined analytical and experimental study of a blade-stiffened composite panel subjected to axial compression was conducted. The study first examined the effects of the differences between a simple model used to design the panel and the actual experimental conditions. It was found that the large imperfection used in the design process compensated for the simplifying assumptions of the design model, and the experimental failure load was only 10% higher than the design load. Next, finite element analyses were performed in order to correlate analytical and experimental results. The buckling loads from finite element analyses agreed well with the experimental failure loads. However, substantial differences were found in the out-of-plane displacements of the panel. Finite element simulations of nonuniform load introduction with general contact definitions improved correlation between the measured and predicted out-of-plane deformations. C1 Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. Gen Elect Corp Res & Dev Ctr, Mech Engn Lab, Schenectady, NY 12309 USA. RP Park, O (reprint author), Lexel Engn, Flint, MI USA. OI Sankar, Bhavani/0000-0002-4556-1982 NR 13 TC 8 Z9 8 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 MAR-APR PY 2001 VL 38 IS 2 BP 379 EP 387 DI 10.2514/2.2772 PG 9 WC Engineering, Aerospace SC Engineering GA 420KR UT WOS:000168004600022 ER PT J AU Joslin, RD Viken, SA AF Joslin, RD Viken, SA TI Baseline validation of unstructured grid Reynolds-averaged Navier-Stokes toward flow control SO JOURNAL OF AIRCRAFT LA English DT Article ID TURBULENT FLOWS C1 Penn State Univ, Appl Res Lab, Computat Modeling & Control Dept, State Coll, PA 16804 USA. NASA, Langley Res Ctr, Flow Phys & Modeling Dept, Hampton, VA 23681 USA. RP Joslin, RD (reprint author), Penn State Univ, Appl Res Lab, Computat Modeling & Control Dept, POB 30, State Coll, PA 16804 USA. NR 17 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 MAR-APR PY 2001 VL 38 IS 2 BP 389 EP 393 DI 10.2514/2.2774 PG 5 WC Engineering, Aerospace SC Engineering GA 420KR UT WOS:000168004600024 ER PT J AU Layne, CS Mulavara, AP McDonald, PV Pruett, CJ Kozlovskaya, IB Bloomberg, JJ AF Layne, CS Mulavara, AP McDonald, PV Pruett, CJ Kozlovskaya, IB Bloomberg, JJ TI Effect of long-duration spaceflight on postural control during self-generated perturbations SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE neuromuscular activation; electromyogram; proprioception ID SPACE-FLIGHT; QUANTITATIVE POSTUROGRAPHY; TREADMILL WALKING; LOWER-LIMB; ADJUSTMENTS; BALANCE; MOVEMENT; SWAY; MICROGRAVITY; INSTABILITY AB This report is the first systematic evaluation of the effects of prolonged weightlessness on the bipedal postural control processes during self-generated perturbations produced by voluntary upper limb movements. Spaceflight impacts humans in a variety of ways, one of which is compromised postflight postural control. We examined the neuromuscular activation characteristics and center of pressure (COP) motion associated with arm movement of eight subjects who experienced long-duration spaceflight (3-6 mo) aboard the Mir space station. Surface electromyography, arm acceleration, and COP motion were collected while astronauts performed rapid unilateral shoulder flexions before and after spaceflight. Subjects generally displayed compromised postural control after flight, as evidenced by modified COP peak-to-peak anterior-posterior and mediolateral excursion, and pathlength relative to preflight values. These changes were associated with disrupted neuromuscular activation characteristics, particularly after the completion of arm acceleration (i.e., when subjects were attempting to maintain upright posture in response to self-generated perturbations). These findings suggest that, although the subjects were able to assemble coordination modes that enabled them to generate rapid arm movements, the subtle control necessary to maintain bipedal equilibrium evident in their preflight performance is compromised after long-duration spaceflight. C1 Univ Houston, Dept Hlth & Human Performance, Houston, TX 77204 USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. Inst Biomed Problems, Moscow 123007, Russia. Tecmath, Troy, MI 48098 USA. RP Layne, CS (reprint author), Univ Houston, Dept Hlth & Human Performance, 104 Garrison, Houston, TX 77204 USA. EM clayne2@bayou.uh.edu RI Kozlovskaya, Inesa/R-9729-2016 NR 38 TC 28 Z9 29 U1 0 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 MAR PY 2001 VL 90 IS 3 BP 997 EP 1006 PG 10 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA 403PJ UT WOS:000167051400032 PM 11181611 ER PT J AU de Gonzalez, ALC Silbergleit, VM Gonzalez, WD Tsurutani, BT AF de Gonzalez, ALC Silbergleit, VM Gonzalez, WD Tsurutani, BT TI Annual variation of geomagnetic activity SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article DE geomagnetic activity; geomagnetic indices; seasonal variation ID SEMIANNUAL VARIATION; STORMS AB The annual variation of geomagnetic activity is studied through the geomagnetic indices aa, Dst and AE, according to different levels of intensity for each of the indices. For thresholds that correspond from moderate to fairly intense storms (i.e., peak aa greater than or equal to 90), the distribution follows the well-known pattern of a seasonal variation, with maxima around the equinoxes and minima near the solstices. Deviations from this behavior are observed when the distribution refers to levels associated with the occurrence of more intense storms. In particular, the annual distribution of days with a geomagnetic index an greater than about 90, shows the occurrence of a peak in July. The contribution of very intense storms (aa greater than or equal to 210) to the July peak, seems to be evenly distributed along the 12 solar cycles covered by this index. Furthermore, the indices Dst and AE, although restricted to a much shorter interval of time (they have been recorded only since 1957), seem as well to show the existence of a peak of occurrence for July. The study done for the indices Dst and AE gives some indication for the existence of another peak in November, also for thresholds associated with intense storms. However, due to the lack of longer records for these indices, the real existence of this peak in the geomagnetic activity is questionable. A statistical analysis of the distribution of events according to the levels of intensity of the aa and Dst is also presented. From this analysis it is seen that the number of occurrences of storms above a given level of intensity of those geomagnetic indices, can be approximated by an exponential law. Furthermore, an estimation of the occurrence of storms during a solar cycle as a function of the peak aa (or aa*) has been also done. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Inst Nacl Pesquisas Espaciais, Sao Paulo, Brazil. Univ Buenos Aires, Fac Ingn, RA-1053 Buenos Aires, DF, Argentina. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP de Gonzalez, ALC (reprint author), Inst Nacl Pesquisas Espaciais, CP 515, Sao Paulo, Brazil. NR 15 TC 17 Z9 17 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 MAR PY 2001 VL 63 IS 4 BP 367 EP 374 PG 8 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 405KE UT WOS:000167157900007 ER PT J AU Tsurutani, BT Papitashvili, VO Lastovicka, J Feldstein, YI AF Tsurutani, BT Papitashvili, VO Lastovicka, J Feldstein, YI TI Interplanetary medium and geophysical phenomena during geomagnetic storms SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Editorial Material C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tsurutani, BT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Lastovicka, Jan/H-6804-2014 OI Lastovicka, Jan/0000-0002-1454-3183 NR 0 TC 0 Z9 0 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 MAR PY 2001 VL 63 IS 5 BP 387 EP 387 DI 10.1016/S1364-6826(00)00159-0 PG 1 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 422HV UT WOS:000168113200001 ER PT J AU Plunkett, SP Thompson, BJ St Cyr, OC Howard, RA AF Plunkett, SP Thompson, BJ St Cyr, OC Howard, RA TI Solar source regions of coronal mass ejections and their geomagnetic effects SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT Meeting of the International-Union-of-Geodesy-and-Geophysics (IUGG) CY JUL 27-28, 1999 CL UNIV BIRMINGHAM, BIRMINGHAM, ENGLAND SP Int Union Geodesy & Geophys HO UNIV BIRMINGHAM DE coronal mass ejections; solar activity; geomagnetic activity ID MAGNETIC STORMS 1978-1979; FLARE MYTH; LASCO OBSERVATIONS; EIT OBSERVATIONS; SMM OBSERVATIONS; SOHO; MISSION; SPEEDS; EVENTS; EARTH AB It is generally accepted that the fast interplanetary manifestations of coronal mass ejections (ICMEs) are the major solar drivers of many space weather phenomena, including large, non-recurrent geomagnetic storms and solar energetic particle events. High-quality synoptic observations of the solar corona, as carried out by the EIT and LASCO experiments on SOHO, provide near real-time imaging of CMEs from the base of the corona out to a projected distance of 30R(circle dot) (R-circle dot is the solar radius). The average characteristics of CMEs observed by LASCO are similar to those from earlier coronagraphs. Most CMEs travel with approximately constant speed through the LASCO field of view. However, a significant number accelerate as they move outward, and some fast events have been observed to decelerate. LASCO has observed a great deal of internal structure in many CMEs. Concave-outward structures that are interpreted as magnetic flux ropes are observed in approximately one third of all events. Complex structures are often observed in the trailing portions of CMEs. Halo CMEs, many of which are very faint, can be routinely observed with LASCO. Extreme-ultraviolet (EW) images of the low corona and solar disk, as recorded by EIT, reveal a complex web of CME signatures. These include large-scale waves in the inner corona associated with CMEs, extended regions of depleted EW intensity, and bright arcades that form following the occurrence of a CME. The combination of LASCO and EIT imagery allows the source regions of halo CMEs to be identified, and can be used to help predict the occurrence of geomagnetic disturbances several days in advance. The most important parameters in determining the geoeffectiveness of an ICME are the magnetic field strength and direction, and the speed of the disturbance. The most intense geomagnetic storms are associated with strong and persistent southward fields, either within the ICME itself or in the compressed sheath of solar wind plasma ahead of it. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. USN, Res Lab, Univ Space Res Assoc, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Computat Phys Inc, Greenbelt, MD 20771 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. RP Plunkett, SP (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Bldg 26,Room G-1,Mail Code 682-3, Greenbelt, MD 20771 USA. RI Thompson, Barbara/C-9429-2012 NR 63 TC 40 Z9 43 U1 0 U2 1 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 MAR PY 2001 VL 63 IS 5 BP 389 EP 402 DI 10.1016/S1364-6826(00)00166-8 PG 14 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 422HV UT WOS:000168113200002 ER PT J AU Tsurutani, BT Zhou, XY Arballo, JK Gonzalez, WD Lakhina, GS Vasyliunas, V Pickett, JS Araki, T Yang, H Rostoker, G Hughes, TJ Lepping, RP Berdichevsky, D AF Tsurutani, BT Zhou, XY Arballo, JK Gonzalez, WD Lakhina, GS Vasyliunas, V Pickett, JS Araki, T Yang, H Rostoker, G Hughes, TJ Lepping, RP Berdichevsky, D TI Auroral zone dayside precipitation during magnetic storm initial phases SO JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT Meeting of the International-Union-of-Geodesy-and-Geophysics (IUGG) CY JUL 27-28, 1999 CL UNIV BIRMINGHAM, BIRMINGHAM, ENGLAND SP Int Union Geodesy & Geophys HO UNIV BIRMINGHAM DE aurora; magnetic storms; magnetosphere ID JANUARY 10; ULTRAVIOLET IMAGER; PRESSURE PULSES; SOLAR-WIND; POLAR; SUBSTORM; WAVES; MAGNETOSPHERE; EMISSIONS; CLOUDS AB Significant charged-particle precipitation occurs in the dayside auroral zone during and after interplanetary shock impingements on the Earth's magnetosphere. The precipitation intensities and spatial and temporal evolution are discussed. Although the post-shock energy flux (1020 erg cm(-2) s(-1)) is lower than that of substorms, the total energy deposition rate may be considerably greater (similar to an order of magnitude) than nightside energy rates due to the greater area of the dayside portion of the auroral oval (defined as extending from 03 MLT through noon to 21 MLT). This dayside precipitation represents direct solar wind energy input into the magnetosphere, ionosphere system. The exact mechanisms for particle energization and precipitation into the ionosphere are not known at this time. Different mechanisms are probably occurring during different portions of the storm initial phase. immediately after shock compression of the magnetosphere. possible precipitation-related mechanisms are: (1) betatron compression of preexisting outer zone magnetospheric particles. The anisotropic plasma is unstable to loss-cone instabilities, leading to plasma wave growth, resonant particle pitch-angle scattering and electron and proton losses into the upper ionosphere. (2) The compression of the magnetosphere can also lead to enhanced field-aligned currents and the formation of dayside double-layers. Finally (3) in the latter stages of the storm initial phase. there is evidence for a long-lasting viscous-like interaction occurring on the Ranks of the magnetopause. Ground-based observations identifying the types of dayside auroral forms would be extremely useful in identifying the specific solar wind energy transfer mechanisms. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. INPE, BR-12200 Sao Paulo, Brazil. Indian Inst Geomagnetism, Mumbai 400005, India. Max Planck Inst Aeron, D-3411 Katlenburg Duhm, Germany. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Kyoto Univ, Dept Geophys, Kyoto 606, Japan. Natl Inst Polar Res, Itabashi Ku, Tokyo 173, Japan. Tech Commun & Serv, Ottawa, ON K2A 2V1, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Tsurutani, BT (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Lakhina, Gurbax /C-9295-2012; OI Lakhina, Gurbax /0000-0002-8956-486X NR 45 TC 38 Z9 40 U1 0 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 MAR PY 2001 VL 63 IS 5 BP 513 EP 522 DI 10.1016/S1364-6826(00)00161-9 PG 10 WC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences SC Geochemistry & Geophysics; Meteorology & Atmospheric Sciences GA 422HV UT WOS:000168113200015 ER PT J AU Chen, G Davis, D Crawford, J Heikes, B O'Sullivan, D Lee, M Eisele, F Mauldin, L Tanner, D Collins, J Barrick, J Anderson, B Blake, D Bradshaw, J Sandholm, S Carroll, M Albercook, G Clarke, A AF Chen, G Davis, D Crawford, J Heikes, B O'Sullivan, D Lee, M Eisele, F Mauldin, L Tanner, D Collins, J Barrick, J Anderson, B Blake, D Bradshaw, J Sandholm, S Carroll, M Albercook, G Clarke, A TI An assessment of HOx chemistry in the tropical Pacific boundary layer: Comparison of model simulations with observations recorded during PEM tropics A SO JOURNAL OF ATMOSPHERIC CHEMISTRY LA English DT Article DE hydroxyl radical; marine boundary layer; peroxides; photochemistry; tropical Pacific ID EQUATORIAL PACIFIC; TROPOSPHERIC NOX; NORTH PACIFIC; PHOTOCHEMISTRY EXPERIMENT; AIRBORNE OBSERVATIONS; HYDROGEN-PEROXIDE; MARINE AIR; OZONE; OH; CLOUD AB Reported are the results from a comparison of OH, H2O2CH3OOH, and O-3 observations with model predictions based on current HOx-CH4 reaction mechanisms. The field observations are those recorded during the NASA GTE field program, PEM-Tropics A. The major focus of this paper is on those data generated on the NASA P-3B aircraft during a mission flown in the marine boundary layer (MBL) near Christmas Island, a site located in the central equatorial Pacific (i.e., 2 degrees N, 157 degrees W). Taking advantage of the stability of the southeastern trade-winds, an air parcel was sampled in a Lagrangian mode over a significant fraction of a solar day. Analyses of these data revealed excellent agreement between model simulated and observed OH. In addition, the model simulations reproduced the major features in the observed diurnal profiles of H2O2 and CH3OOH. In the case of O-3, the model captured the key observational feature which involved an early morning maximum. An examination of the MBL HOx budget indicated that the O(D-1) + H2O reaction is the major source of HOx while the major sinks involve both physical and chemical processes involving the peroxide species, H2O2 and CH3OOH. Overall, the generally good agreement between model and observations suggests that our current understanding of HOx-CH4 chemistry in the tropical MBL is quite good; however, there remains a need to critically examine this chemistry when both CH2O and HO2 are added to the species measured. C1 Georgia Inst Technol, Atlanta, GA 30332 USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. Univ Rhode Isl, Narragansett, RI USA. USN Acad, Annapolis, MD 21402 USA. Korea Ocean Res & Dev Inst, Seoul, South Korea. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Univ Calif Irvine, Irvine, CA USA. Univ Michigan, Ann Arbor, MI 48109 USA. Univ Hawaii, Honolulu, HI 96822 USA. RP Chen, G (reprint author), Georgia Inst Technol, Atlanta, GA 30332 USA. RI Crawford, James/L-6632-2013; Mason, Robert/A-6829-2011; OI Crawford, James/0000-0002-6982-0934; O'Sullivan, Daniel/0000-0001-9104-5703 NR 50 TC 19 Z9 19 U1 2 U2 10 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-7764 J9 J ATMOS CHEM JI J. Atmos. Chem. PD MAR PY 2001 VL 38 IS 3 BP 317 EP 344 DI 10.1023/A:1006402626288 PG 28 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA 410JA UT WOS:000167435800004 ER PT J AU Perusek, GP Davis, BL Sferra, JJ Courtney, AC D'Andrea, SE AF Perusek, GP Davis, BL Sferra, JJ Courtney, AC D'Andrea, SE TI An extensometer for global measurement of bone strain suitable for use in vivo in humans SO JOURNAL OF BIOMECHANICS LA English DT Article DE bone strain; extensometer; capacitive sensor; strain gage; adaptive remodeling ID FORCES; MASS AB An axial extensometer able to measure global bone strain magnitudes and rates encountered during physiological activity, and suitable for use in vivo in human subjects, is described. The extensometer uses paired capacitive sensors mounted to intraosseus pins and allows measurement of strain due to bending in the plane of the extensometer as well as uniaxial compression or tension. Data are presented for validation of the device against a surface-mounted strain gage in an acrylic specimen under dynamic four-point bending, with square wave and sinusoidal loading inputs up to 1500 mu epsilon and 20 Hz, representative of physiological strain magnitudes and frequencies. Pearson's correlation coefficient (r) between extensometer and strain gage ranged from 0.960 to 0.999. Mean differences between extensometer and strain gage ranged up to 15.3 mu epsilon Errors in the extensometer output were directly proportional to the degree of bending that occurs in the specimen, however, these errors were predictable and less than 1 mu epsilon for the loading regime studied. The device is capable of tracking strain rates in excess of 90,000 mu epsilon /s. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, John H Glen Res Ctr Lewis Field, Cleveland, OH 44135 USA. Case Western Reserve Univ, Cleveland, OH 44195 USA. Cleveland Clin Fdn, Cleveland, OH 44195 USA. Barry Univ, Grad Sch Med Sci, Miami Shores, FL 33161 USA. RP Perusek, GP (reprint author), NASA, John H Glen Res Ctr Lewis Field, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 11 TC 6 Z9 7 U1 1 U2 4 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0021-9290 J9 J BIOMECH JI J. Biomech. PD MAR PY 2001 VL 34 IS 3 BP 385 EP 391 DI 10.1016/S0021-9290(00)00197-4 PG 7 WC Biophysics; Engineering, Biomedical SC Biophysics; Engineering GA 411DH UT WOS:000167482500013 PM 11182131 ER PT J AU De Stasio, G Gilbert, B Frazer, BH Nealson, KH Conrad, PG Livi, V Labrenz, M Banfield, JF AF De Stasio, G Gilbert, B Frazer, BH Nealson, KH Conrad, PG Livi, V Labrenz, M Banfield, JF TI The multidisciplinarity of spectromicroscopy: from geomicrobiology to archaeology SO JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA LA English DT Article; Proceedings Paper CT 8th International Conference on Electronic Spectroscopy and Structure CY AUG 08-12, 2000 CL UNIV CALIF, CLARK KERR CAMPUS, BERKELEY, CALIFORNIA HO UNIV CALIF, CLARK KERR CAMPUS DE X-PEEM; spectromicroscopy; ZnS precipitating bacteria; banded iron formation; Roman silver coin ID X-RAY; PHOTOEMISSION; MICROSCOPE; RESOLUTION; MEPHISTO; FILMS; TESTS; BORON AB Synchrotron X-ray PhotoElectron Emission Microscopy (X-PEEM) is a useful tool to investigate the microchemical composition of a variety of different samples, including cells in culture, tissue sections, magnetic material, bacteria, rocks, materials science, tribology and archaeology specimens. The MEPHISTO X-PEEM, installed at the Wisconsin Synchrotron Radiation Center, reached a peak resolution of 20 nm, has been extensively used for the last 4 years to explore all of the above systems. The experiments reported here are some of the most unusual ones for this technique: ZnS precipitating bacteria, Mn and Fe oxide rocks and archaeological coins. The microchemistry of each one of these samples delivered new results. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. Ecole Polytech Fed Lausanne, CH-1015 Lausanne, Switzerland. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Penn, Dept Archaeol, Philadelphia, PA 19104 USA. Univ Wisconsin, Dept Geol & Geophys, Madison, WI 53706 USA. RP De Stasio, G (reprint author), Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. RI Gilbert, Benjamin/E-3182-2010; Gilbert, Pupa/A-6299-2010 OI Gilbert, Pupa/0000-0002-0139-2099 NR 21 TC 17 Z9 17 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0368-2048 J9 J ELECTRON SPECTROSC JI J. Electron Spectrosc. Relat. Phenom. PD MAR PY 2001 VL 114 BP 997 EP 1003 DI 10.1016/S0368-2048(00)00369-8 PG 7 WC Spectroscopy SC Spectroscopy GA 417JW UT WOS:000167832700154 ER PT J AU Gilbert, B Margaritondo, G Douglas, S Nealson, KH Egerton, RF Rempfer, GF De Stasio, G AF Gilbert, B Margaritondo, G Douglas, S Nealson, KH Egerton, RF Rempfer, GF De Stasio, G TI XANES microspectroscopy of biominerals with photoconductive charge compensation SO JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA LA English DT Article; Proceedings Paper CT 8th International Conference on Electronic Spectroscopy and Structure CY AUG 08-12, 2000 CL UNIV CALIF, CLARK KERR CAMPUS, BERKELEY, CALIFORNIA HO UNIV CALIF, CLARK KERR CAMPUS DE microchemical analysis; photoconductivity; charging; mineralization; X-ray absorption; spectromicroscopy ID SPECTROSCOPY; SILICON AB Specimen charging under X-ray illumination is a well known phenomenon that can seriously obstruct the analysis of insulating samples. Synchrotron X-PEEM spectromicroscopy can reach a lateral resolution of 20 nm, 1-2 orders of magnitude larger than electron microscopies, but has the added capacity to probe oxidation state through total yield X-ray absorption near edge structure (XANES) spectroscopy. This capability may be compromised, however, if specimen charging restricts electron emission, as was encountered in the study of silicified bacteria from an Icelandic hot spring microbial mat. Bacteria living in an environment containing a high concentration of dissolved silica provide nucleation sites for amorphous silicate precipitation, a process which may lead to the preservation of the cellular structure, i.e. fossilization. TEM studies of bacteria in progressive stages of mineralization showed that mineral formation was initiated in the extracellular sheath, reaching the cell interior after death. Spectromicroscopy at the Si L-edge of sectioned mineralized bacteria encountered major charging difficulties, which were relieved by simultaneously illuminating the specimen with 325 nm HeCd laser light during the analysis. The low energy light excites mobile free electrons below the work function threshold, which can offset surface positive charge. This approach allowed spectroscopy to be performed from microscopic areas, and may be applicable to a wider range of insulating samples. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Ecole Polytech Fed Lausanne, CH-1015 Lausanne, Switzerland. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. Univ Alberta, Dept Phys, Edmonton, AB T6G 2J1, Canada. Portland State Univ, Dept Phys, Portland, OR USA. Univ Wisconsin, Dept Geol, Madison, WI USA. RP Gilbert, B (reprint author), Ecole Polytech Fed Lausanne, CH-1015 Lausanne, Switzerland. RI Margaritondo, Giorgio/B-1367-2008; Gilbert, Benjamin/E-3182-2010; Gilbert, Pupa/A-6299-2010 OI Gilbert, Pupa/0000-0002-0139-2099 NR 14 TC 6 Z9 6 U1 0 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0368-2048 J9 J ELECTRON SPECTROSC JI J. Electron Spectrosc. Relat. Phenom. PD MAR PY 2001 VL 114 BP 1005 EP 1011 DI 10.1016/S0368-2048(00)00342-X PG 7 WC Spectroscopy SC Spectroscopy GA 417JW UT WOS:000167832700155 ER PT J AU Johansen, ES Rediniotis, OK Jones, G AF Johansen, ES Rediniotis, OK Jones, G TI The compressible calibration of miniature multi-hole probes SO JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID FLOW MEASUREMENTS AB This work presents the development of a data reduction algorithm for non-nulling, multihole pressure probes in compressible, subsonic flowfields. The algorithm is able to reduce data from any 5- or 7-hole probe and generate very accurate predictions of the velocity magnitude and direction, total and static pressures, Mach and Reynolds number and fluid properties like the density and viscosity. The algorithm utilizes a database of four novel miniature 7-hole probes that have been calibrated at NASA Langley Flow Modeling and Control Branch for the entire subsonic regime. Each of the probes had a conical tip with dimeter of 1.65 mm. Excellent prediction capabilities are demonstrated with maximum errors in angle prediction less than 0.6 degrees and maximum errors in velocity prediction less than 1 percent, both with 99 percent confidence. C1 Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. Texas A&M Univ, Dept Aerosp Engn, College Stn, TX 77843 USA. NASA, Langley Res Ctr, Flow Modeling & Control Branch, Hampton, VA 23681 USA. RP Johansen, ES (reprint author), Texas A&M Univ, Dept Mech Engn, College Stn, TX 77843 USA. NR 14 TC 18 Z9 19 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0098-2202 J9 J FLUID ENG-T ASME JI J. Fluids Eng.-Trans. ASME PD MAR PY 2001 VL 123 IS 1 BP 128 EP 138 DI 10.1115/1.1334377 PG 11 WC Engineering, Mechanical SC Engineering GA 412CM UT WOS:000167536500018 ER PT J AU Osherovich, V AF Osherovich, V TI Comment on "On the determination of electron polytrope indices within coronal mass ejections in the solar wind" by J. T. Gosling SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Editorial Material ID INTERPLANETARY MAGNETIC CLOUDS; HELIOGRAPHIC LATITUDES; TEMPERATURE; DISTRIBUTIONS; GENERATION; DRIVEN C1 Raytheon Informat Technol & Sci Serv, Lanham, MD USA. RP Osherovich, V (reprint author), NASA, Goddard Space Flight Ctr, Code 6900-2,Bldg 1,Rm 253, Greenbelt, MD 20771 USA. NR 23 TC 3 Z9 3 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 MAR 1 PY 2001 VL 106 IS A3 BP 3703 EP 3707 DI 10.1029/2000JA000303 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407GN UT WOS:000167264000009 ER PT J AU Birn, J Drake, JF Shay, MA Rogers, BN Denton, RE Hesse, M Kuznetsova, M Ma, ZW Bhattacharjee, A Otto, A Pritchett, PL AF Birn, J Drake, JF Shay, MA Rogers, BN Denton, RE Hesse, M Kuznetsova, M Ma, ZW Bhattacharjee, A Otto, A Pritchett, PL TI Geospace Environmental Modeling (GEM) Magnetic Reconnection Challenge SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID X-LINE AB The Geospace Environmental Modeling (GEM) Reconnection Challenge project is presented and the important results, which are presented in a series of companion papers, are summarized. Magnetic reconnection is studied in a simple Harris sheet configuration with a specified set of initial conditions, including a finite amplitude, magnetic island perturbation to trigger the dynamics. The evolution of the system is explored with a broad variety of codes, ranging from fully electromagnetic particle in cell (PIC) codes to conventional resistive magnetohydrodynamic (MHD) codes, and the results are compared. The goal is to identify the essential physics which is required to model collisionless magnetic reconnection. All models that include the Hall effect in the generalized Ohm's law produce essentially indistinguishable rates of reconnection, corresponding to nearly Alfvenic inflow velocities. Thus the rate of reconnection is insensitive to the specific mechanism which breaks the frozen-in condition, whether resistivity, electron inertia, or electron thermal motion. The reconnection rate in the conventional resistive MHD model, in contrast, is dramatically smaller unless a large localized or current dependent resistivity is used. The Hall term brings the dynamics of whistler waves into the system. The quadratic dispersion property of whistlers (higher phase speed at smaller spatial scales) is the key to understanding these results. The implications of these results fbr trying to model the global dynamics of the magnetosphere are discussed. C1 Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. Univ Maryland, Inst Plasma Res, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Electrodynam Branch, Greenbelt, MD 20771 USA. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Univ Alaska, Inst Geophys, Fairbanks, AK 99775 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. RP Birn, J (reprint author), Univ Calif Los Alamos Natl Lab, POB 1663, Los Alamos, NM 87545 USA. RI Hesse, Michael/D-2031-2012; Kuznetsova, Maria/F-6840-2012; Ma, Zhiwei/F-6986-2013; Shay, Michael/G-5476-2013 NR 16 TC 718 Z9 730 U1 7 U2 56 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 MAR 1 PY 2001 VL 106 IS A3 BP 3715 EP 3719 DI 10.1029/1999JA900449 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407GN UT WOS:000167264000011 ER PT J AU Hesse, M Birn, J Kuznetsova, M AF Hesse, M Birn, J Kuznetsova, M TI Collisionless magnetic reconnection: Electron processes and transport modeling SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID HYBRID SIMULATIONS; PARTICLE SIMULATION; MAGNETOTAIL RECONNECTION; EARTHS MAGNETOPAUSE; FIELD; DISSIPATION; DYNAMICS; PLASMAS; REGION; LAW AB Particle-in-cell simulations are used to investigate collisionless magnetic reconnection in thin current sheets, based on the configuration chosen for the Geospace Environment Modeling (GEM) magnetic reconnection challenge [Birn et al., this issue]. The emphasis is on the overall evolution, as well as details of the particle dynamics in the diffusion region. Here electron distributions show clear signatures of nongyrotropy, whereas ion distributions are simpler in structure. The investigations are extended to current sheets of different widths. Here we derive a scaling law for the evolution dependence on current sheet width. Finally, we perform a detailed comparison between a kinetic and Hall-magnetohydrodynamic model of the same system. The comparison shows that although electric fields appear to be quite similar, details of the evolution appear to be considerably different, indicative of the role of further anisotropies in the ion pressures. C1 NASA, Goddard Space Flight Ctr, Electrodynam Branch, Greenbelt, MD 20771 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Raytheo STX, Greenbelt, MD 20771 USA. RP Hesse, M (reprint author), NASA, Goddard Space Flight Ctr, Electrodynam Branch, Code 696, Greenbelt, MD 20771 USA. RI Hesse, Michael/D-2031-2012; Kuznetsova, Maria/F-6840-2012 NR 33 TC 129 Z9 133 U1 3 U2 8 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 MAR 1 PY 2001 VL 106 IS A3 BP 3721 EP 3735 DI 10.1029/1999JA001002 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407GN UT WOS:000167264000012 ER PT J AU Birn, J Hesse, M AF Birn, J Hesse, M TI Geospace Environment Modeling (GEM) magnetic reconnection challenge: Resistive tearing, anisotropic pressure and Hall effects SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID TEMPERATURE ANISOTROPY; MAGNETOTAIL DYNAMICS; ENERGY RELEASE; SIMULATIONS; FLUID AB The nonlinear evolution of resistive tearing is studied ire various regimes, including one-fluid isotropic MHD, anisotropic (gyrotropic) MI-ID with terms approximating the effects of anisotropy driven instabilities, and Hall-MI-ID. Both uniform resistivity and spatially localized resistivity are investigated. The initial state is a plane one-dimensional current sheet with an initial perturbation representing a periodic structure with magnetic islands and x type neutral points, chosen for the "GEM magnetic reconnection challenge" [Birn et nl., this issue]. In the absence of dissipation, within ideal MHD, the initially imposed x type configuration collapses into a thin current sheet of finite length, while the magnetic islands contract, conserving their magnetic flux. The current density in the thin sheet becomes significantly enhanced, so that microscopic dissipation mechanisms can be expected to be ignited, even if they were absent in the initial state. Finite resistivity enables reconnection, and the growth of magnetic islands as in particle simulations. A comparison of reconnection rates shows that for the chosen initial current sheet thickness, a localized resistivity, corresponding to a Lundquist number (magnetic Reynolds number) of order unity, is necessary to approximate the growth and the reconnection electric field in the particle simulations. Pressure anisotropy, governed by double adiabatic conservation laws (modified by Ohmic heating), lends to reduced growth rates. This reduction is drastic for uniform resistivity. Isotropizing terms, modeling the effects of anisotropy driven microinstabilities again destabilize. Hall-MHD simulations can reproduce the fast growth of the particle simulations. The various models show both similarities and dissimilarities in their spatial structure. For similar amounts of reconnected flux, the variation of the normal magnetic field and of the (ion) how speed along the current sheet are similar, but electric field and current density show significant differences. C1 NASA, Goddard Space Flight Ctr, Electrodynam Branch, Greenbelt, MD 20771 USA. Univ Calif Los Alamos Natl Lab, Space & Atmospher Sci Grp, Los Alamos, NM 87545 USA. RP Birn, J (reprint author), NASA, Goddard Space Flight Ctr, Electrodynam Branch, Code 696, Greenbelt, MD 20771 USA. RI Hesse, Michael/D-2031-2012 NR 17 TC 85 Z9 87 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 MAR 1 PY 2001 VL 106 IS A3 BP 3737 EP 3750 DI 10.1029/1999JA001001 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407GN UT WOS:000167264000013 ER PT J AU Kuznetsova, MM Hesse, M Winske, D AF Kuznetsova, MM Hesse, M Winske, D TI Collisionless reconnection supported by nongyrotropic pressure effects in hybrid and particle simulations SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC RECONNECTION; CURRENT SHEETS; TEARING MODE; X-LINE; FIELD; INSTABILITIES; DISSIPATION; TRANSPORT; REGION; PLASMA AB This paper presents the detailed comparative analysis of full particle and hybrid simulations of collisionless magnetic reconnection. The comprehensive hybrid simulation code employed in this study incorporates essential electron kinetics in terms of the evolution of the full electron pressure tensor in addition to the full ion kinetics and electron bulk flow inertia effects. As was demonstrated in our previous publications, the electron nongyrotropic pressure effects play the dominant role in supporting the reconnection electric field in the immediate vicinity of the neutral X point. The simulation parameters are chosen to match those of the Geospace Environmental Modeling (GEM) "Reconnection Challenge." It is that these comprehensive hybrid simulations perfectly reproduce the results of full particle simulations in many details. Specifically, the time evolutions of the reconnected magnetic flux and the reconnection electric field,, as well as spatial distributions of current density and magnetic field at all stages of the reconnection process, are found to be nearly identical for both simulations. Comparisons of variations of characteristic quantities along the x and z axes centered around the dominating X points also revealed a remarkable agreement. Noticeable differences are found only in electron temperature profiles, i.e., in the diagonal electron pressure tensor components. The deviation in the electron heating pattern in hybrid simulations from that observed in particle simulations, However, does not affect parameters essential for the reconnection process. In particular, the profiles of the off-diagonal components of the electron pressure tensor are found to be very similar for both runs and appear unaffected by heat flux effects. Both simulations also demonstrate that the E-y component of the electric field is nearly constant inside the diffusion region where ions are nonmagnetized. Wt: demonstrate that the simple analytical estimate for the reconnection electric field as a convection electric field at the edge of the diffusion region very well reproduces the reconnection electric field observed in the simulations. C1 Univ Calif Los Alamos Natl Lab, Div Appl Theoret Phys, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Electrodynam Branch, Greenbelt, MD 20771 USA. RP Kuznetsova, MM (reprint author), Raytheon ITSS Corp, Lanham, MD USA. RI Hesse, Michael/D-2031-2012; Kuznetsova, Maria/F-6840-2012 NR 32 TC 70 Z9 72 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 MAR 1 PY 2001 VL 106 IS A3 BP 3799 EP 3810 DI 10.1029/1999JA001003 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407GN UT WOS:000167264000018 ER PT J AU Ieda, A Fairfield, DH Mukai, T Saito, Y Kokubun, S Liou, K Meng, CI Parks, GK Brittnacher, MJ AF Ieda, A Fairfield, DH Mukai, T Saito, Y Kokubun, S Liou, K Meng, CI Parks, GK Brittnacher, MJ TI Plasmoid ejection and auroral brightenings SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GEOTAIL OBSERVATIONS; SUBSTORM ONSETS; INNER MAGNETOTAIL; FIELD VARIATIONS; FLOW; TAIL; INTENSIFICATIONS; SIGNATURES; EVOLUTION; DYNAMICS AB Geotail plasma and magnetic field observations of 24 plasmoids between 21 and 29 R-E have been compared with Polar ultraviolet observations of auroral brightenings. Both single and multiple plasmoids almost always corresponded to brightenings, but the brightenings were sometimes weak and spatially limited and did not always grow to a global substorm. Even a case where a plasmoid event occurred with fast postplasmoid flow corresponded to a weak brightening but no substorm. Some brightenings did not correspond to plasmoids, but these brightenings were observed away from the longitude of Geotail, indicating that plasmoids have a small longitudinal extent in the near tail. The plasmoids were occasionally observed before the brightenings but more frequently were observed 0-2 min after the brightenings with the delays probably due to the transit time to the observation point. It seems likely that; formation of a near-Earth neutral line causes each brightening in the polar ionosphere. but these formations do not always lead to a full-fledged substorm. What additional circumstance causes development of a full, large-scale substorm remains an open question. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Inst Space & Astronaut Sci, Sagamihara, Kanagawa 229, Japan. Nagasaki Univ, Solar Terr Environm Lab, Aichi 442, Japan. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. Univ Washington, Geophys Program, Seattle, WA 98195 USA. RP Ieda, A (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RI Liou, Kan/C-2089-2016 OI Liou, Kan/0000-0001-5277-7688 NR 29 TC 68 Z9 69 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 MAR 1 PY 2001 VL 106 IS A3 BP 3845 EP 3857 DI 10.1029/1999JA000451 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407GN UT WOS:000167264000021 ER PT J AU Fok, MC Moore, TE Spjeldvik, WN AF Fok, MC Moore, TE Spjeldvik, WN TI Rapid enhancement of radiation belt electron fluxes due to substorm dipolarization of the geomagnetic field SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLASMA SHEET ION; RING CURRENT; ENERGIZATION; INJECTIONS; SIMULATION; DIFFUSION; DYNAMICS; PHASE; STORM; MODEL AB The classical pure radial diffusion mechanism appears not to fully explain the frequently observed rapid enhancement in the timescales of minutes to hours in the radiation belt electron fluxes in the Earth's magnetosphere. We here consider other physical mechanisms, such as energization mechanisms associated with substorm processes, to account for these sudden increases. A three-dimensional electron kinetic model is used to simulate the dynamics of the geomagnetically trapped population of radiation belt electrons during a substorm injection event. In the past this model has been extensively used to study dynamics of energetic ions in the ring current. This work, for the first time, constitutes the development of a combined convection and diffusion model to radiation belt electrons in the 0.04-4 MeV kinetic energy range. The Tsyganenko 89 geomagnetic field model is used to simulate the time-varying terrestrial magnetosphere during the growth phase elongation and the expansion phase contraction. We find that inductive electric field associated with the magnetic reconfiguration process is needed in order to transport substorm electrons into the trapped particle region of the magnetosphere. The maximum enhancement in energetic electron fluxes is found to be located around the geosynchronous orbit location (L = 6.6), with up to 2 orders of magnitude enhancement in the total fluxes (0.04-4 MeV). Although this enhancement in the inner magnetosphere is very sensitive to the temperature and, to a less extent, density of the source population in the plasma sheet, we suggest that the substorm-associated energization in the magnetotail and the subsequent adiabatic acceleration in the earthward region account for the enhanced MeV electrons (killer electrons) seen at the geosynchronous orbit during storms and substorms. C1 NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Weber State Univ, Dept Phys, Ogden, UT 84408 USA. RP Fok, MC (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Code 692, Greenbelt, MD 20771 USA. RI Moore, Thomas/D-4675-2012; Fok, Mei-Ching/D-1626-2012 OI Moore, Thomas/0000-0002-3150-1137; NR 25 TC 46 Z9 47 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 MAR 1 PY 2001 VL 106 IS A3 BP 3873 EP 3881 DI 10.1029/2000JA000150 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407GN UT WOS:000167264000023 ER PT J AU Wang, PKC Yee, J Hadaegh, FY AF Wang, PKC Yee, J Hadaegh, FY TI Synchronized rotation of multiple autonomous spacecraft with rule-based controls: Experimental study SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB An experimental study is made on the synchronized continuous-rotation of multiple air-levitated autonomous model spacecraft about a fixed axis by means of simple rule-based controls. These controls differ from the conventional ones, which require processing of numerical sensor data. The controls depend solely on the occurrence and timing of certain discrete event sequences. Thus, the controlled model spacecraft is a hybrid continuous-time and discrete-event system. Experimental results show that the proposed rule-based controls are effective in achieving rotational motion with synchronized angular velocity and phase. A description of the experimental setup and a brief discussion of the design of the air-levitated model spacecraft is given. Then, the details on the development of rule-based controls and the derivation of a dynamic model for the resulting hybrid system are presented followed by the presentation and interpretation of the experimental results. C1 Univ Calif Los Angeles, Dept Elect Engn, Los Angeles, CA 90095 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Wang, PKC (reprint author), Univ Calif Los Angeles, Dept Elect Engn, Los Angeles, CA 90095 USA. NR 10 TC 19 Z9 20 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 2001 VL 24 IS 2 BP 352 EP 359 DI 10.2514/2.4719 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 410WA UT WOS:000167463000020 ER PT J AU Mesbahi, M Hadaegh, FY AF Mesbahi, M Hadaegh, FY TI Formation flying control of multiple spacecraft via graphs, matrix inequalities, and switching SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Formation flying has been identified as an enabling technology for many of the future NASA deep space and earth science missions. Various methodologies have been considered for formation control of multiple spacecraft, each offering different degrees of generality and flexibility. One popular framework is known as leader following (LF). Several results in the LF framework for the formation flying control are presented. In this direction, ideas from elementary graph theory and linear matrix inequalities are combined with logic-based switching to shed light on the class of control designs that are feasible through LF for a representative set of formation flying scenarios. C1 Univ Minnesota, Dept Aerosp Engn & Mech, Minneapolis, MN 55455 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mesbahi, M (reprint author), Univ Minnesota, Dept Aerosp Engn & Mech, Minneapolis, MN 55455 USA. EM mesbahi@aem.umn.edu; fred.y.hadaegh@jpl.nasa.gov NR 14 TC 92 Z9 95 U1 1 U2 9 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 2001 VL 24 IS 2 BP 369 EP 377 DI 10.2514/2.4721 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 410WA UT WOS:000167463000022 ER PT J AU Horner, G Taleghani, B AF Horner, G Taleghani, B TI Single axis piezoceramic gimbal SO JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES LA English DT Article AB This paper describes the fabrication, testing, and analysis of a single axis piezoceramic gimbal. The fabrication process consists of pre-stressing a piezoceramic wafer using a high-temperature thermoplastic polyimide and a metal foil. The differential thermal expansion between the ceramic and metal induces a curvature. The piezoceramic is mounted on a support mechanism and a mirror is attached to the piezoceramic. A finite element analysis of the gimbal is described and the predicted gimbal angle versus applied voltage is compared to experimental results. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. USA, Vehicle Technol Ctr, Hampton, VA USA. RP Horner, G (reprint author), NASA, Langley Res Ctr, MS 230, Hampton, VA 23681 USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU SAGE PUBLICATIONS LTD PI LONDON PA 6 BONHILL STREET, LONDON EC2A 4PU, ENGLAND SN 1045-389X J9 J INTEL MAT SYST STR JI J. Intell. Mater. Syst. Struct. PD MAR PY 2001 VL 12 IS 3 BP 157 EP 160 DI 10.1106/LA9C-7PHA-28H7-MEQP PG 4 WC Materials Science, Multidisciplinary SC Materials Science GA 534PL UT WOS:000174594800002 ER PT J AU Boyan, JA Moore, AW AF Boyan, JA Moore, AW TI Learning evaluation functions to improve optimization by local search SO JOURNAL OF MACHINE LEARNING RESEARCH LA English DT Article ID ALGORITHMS AB This paper describes algorithms that learn to improve search performance on large-scale optimization tasks. The main algorithm, STAG, works by learning an evaluation function that predicts the outcome of a local search algorithm, such as hillclimbing or WALKSAT, from features of states visited during search. The learned evaluation function is then used to bias future search trajectories toward better optima on the same problem. Another algorithm, X-STAGE, transfers previously learned evaluation functions to new, similar optimization problems. Empirical results are provided on seven large-scale optimization domains: bin-packing, channel routing, Bayesian network structure-finding, radiotherapy treatment planning, cartogram design, Boolean satisfiability, and Boggle board setup. C1 NASA, Ames Res Ctr, Computat Sci Div, Moffett Field, CA 94035 USA. Carnegie Mellon Univ, Dept Comp Sci, Pittsburgh, PA 15213 USA. RP ITA Software, Cambridge, MA USA. EM JUSTIN@BOYAN.COM; AWM@CS.CMU.EDU NR 52 TC 6 Z9 7 U1 0 U2 1 PU MICROTOME PUBL PI BROOKLINE PA 31 GIBBS ST, BROOKLINE, MA 02446 USA SN 1532-4435 J9 J MACH LEARN RES JI J. Mach. Learn. Res. PD SPR PY 2001 VL 1 IS 2 BP 77 EP 112 DI 10.1162/15324430152733124 PG 36 WC Automation & Control Systems; Computer Science, Artificial Intelligence SC Automation & Control Systems; Computer Science GA 512RF UT WOS:000173336800001 ER PT J AU Rathz, TJ Robinson, MB Li, D Workman, GL Williams, G AF Rathz, TJ Robinson, MB Li, D Workman, GL Williams, G TI Study of the containerless undercooling of Ti-Ce immiscible alloys SO JOURNAL OF MATERIALS SCIENCE LA English DT Article AB Ti-Ce immiscible alloys of compositions across the miscibility gap were containerlessly processed in both a low-gravity and a unit-gravity environment. Although undercooling of the single-phase liquid into the miscibility gap could not be observed, undercooling did occur across the miscibility gap for the separated liquid Ti-rich phase. The low gravity, quiescent environment favored higher undercooling over the unit-gravity samples. Every undercooled sample had massive separation of the liquid phases. Metallurgical analysis of samples undercooled in unit-gravity showed signs of vigorous convective stirring and shearing of the L-1 Ti-liquid by the applied levitation electromagnetic field. In low-gravity processed samples, the L-1 liquid formed a near-concentric sphere within a Ce shell with some residual smaller spherical particles dispersed throughout the Ce. This configuration is predicted from wetting theory and from Marangoni separation. Plots of both the melting and solidification temperatures indicate that the monotectic temperature is 1831 +/- 12 degreesK rather than the 1723 degreesK as reported in the literature. From chemical and diffraction analysis, the solubility of Ce in the Ti-rich phase was found to be extended; also, some cerium oxide precipitates formed but no perceptible dissolved oxygen within the Ce or Ti phases was found which indicates that the higher monotectic temperature reported here is probably not an oxygen effect. (C) 2001 Kluwer Academic Publishers. C1 Univ Alabama, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Queens Univ, Kingston, ON, Canada. RP Rathz, TJ (reprint author), Univ Alabama, Huntsville, AL 35899 USA. NR 26 TC 9 Z9 13 U1 2 U2 6 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 MAR PY 2001 VL 36 IS 5 BP 1183 EP 1188 DI 10.1023/A:1004885926618 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA 412VE UT WOS:000167574400016 ER PT J AU Gan, YX Chu, F Aglan, H Faughnan, P Bryan, C AF Gan, YX Chu, F Aglan, H Faughnan, P Bryan, C TI Overloading failure analysis of particulate and short fiber filled PTFE composites SO JOURNAL OF MATERIALS SCIENCE LETTERS LA English DT Article ID POLYSTYRENE; MORPHOLOGY; BLENDS C1 Tuskegee Univ, Dept Mech Engn, Tuskegee, AL 36088 USA. NASA, Kennedy Space Ctr, Kennedy Space Ctr, FL USA. RP Aglan, H (reprint author), Tuskegee Univ, Dept Mech Engn, Tuskegee, AL 36088 USA. NR 24 TC 2 Z9 3 U1 0 U2 3 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 MAR PY 2001 VL 20 IS 6 BP 581 EP 584 DI 10.1023/A:1010953205936 PG 4 WC Materials Science, Multidisciplinary SC Materials Science GA 426CZ UT WOS:000168333300028 ER PT J AU Walker, JS Volz, MP Szofran, FR Motakef, S AF Walker, JS Volz, MP Szofran, FR Motakef, S TI Effects of a rotating magnetic field on gas transport during detached crystal growth in space SO JOURNAL OF MATERIALS SYNTHESIS AND PROCESSING LA English DT Article DE numerical modeling; Bridgman crystal growth; rotating magnetic field; gas transport; microgravity ID SOLIDIFICATION; FLOW; DRIVEN AB During the detached Bridgman growth of semiconductor crystals, the melt has a short free surface, which is detached from the ampul wall near the crystal-melt interface, thus eliminating the crystal defects caused by contact with the ampul wall. Recent modeling has indicated that initiation and continuation of detached growth depends on the rate of transport of dissolved gas from the crystal-melt interface, where gas is rejected into the melt, to the detached free surface, where evaporating gas maintains the pressure on the free surface. Here we use numerical modeling to investigate whether the application of a rotating magnetic field increases or decreases the transport of rejected gas to the detached free surface. Unfortunately, the results show that a rotating magnetic field almost always decreases the evaporation rate at the detached free surface. The exception is an insignificant increase for a short period at the beginning of crystal growth for a few circumstances. The evaporation rate decreases as the strength of the rotating magnetic field is increased. C1 Univ Illinois, Urbana, IL 61801 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Cape Simulat, Newton, MA 02158 USA. RP Walker, JS (reprint author), Univ Illinois, Urbana, IL 61801 USA. NR 15 TC 1 Z9 2 U1 1 U2 1 PU CONSULTANTS BUREAU PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1064-7562 J9 J MATER SYNTH PROCES JI J. Mater. Synth. Process PD MAR PY 2001 VL 9 IS 2 BP 73 EP 81 DI 10.1023/A:1011308424767 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA 465EX UT WOS:000170577600003 ER PT J AU Lewicki, DG Handschuh, RF Spievak, LE Wawrzynek, PA Ingraffea, AR AF Lewicki, DG Handschuh, RF Spievak, LE Wawrzynek, PA Ingraffea, AR TI Consideration of moving tooth load in gear crook propagation predictions SO JOURNAL OF MECHANICAL DESIGN LA English DT Article ID STRESS INTENSITY FACTORS; FATIGUE-CRACK GROWTH; NUMERICAL-METHODS; TEETH AB Robust gear designs consider not only crack initiation, but crack propagation trajectories for a fail-safe design. In actual gear operation, the magnitude as well as the position of the force changes as the gear rotates through the mesh. A study to determine the effect of moving gear tooth load on crack propagation predictions was performed. Two-dimensional analysis of an involute spur gear and three-dimensional analysis of a spiral-bevel pinion gear using the finite element method and boundary element method were studied and compared to experiments. A modified theory for predicting gear crack propagation paths bused on the criteria of Erdogam and Sih [18] was investigated. Crack simulation based on calculated stress intensity factors and mixed mode crack angle prediction techniques rising a simple static analysis in which the tooth load was located at the highest point of single tooth contact was validated. For three-dimensional analysis, however, the analysis was valid only as long as the crack did not approach the contact region on the tooth. C1 USA, Res Lab, NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Lewicki, DG (reprint author), USA, Res Lab, NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 24 TC 10 Z9 12 U1 0 U2 4 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 1050-0472 J9 J MECH DESIGN JI J. Mech. Des. PD MAR PY 2001 VL 123 IS 1 BP 118 EP 124 DI 10.1115/1.1338118 PG 7 WC Engineering, Mechanical SC Engineering GA 417LJ UT WOS:000167836200018 ER PT J AU Park, S Srivastava, D Cho, K AF Park, S Srivastava, D Cho, K TI endo-fullerene and doped diamond nanocrystallite-based models of qubits for solid-state quantum computers SO JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY LA English DT Article DE endo-fullerene; doped diamond nanocrystallite; solid-state quantum computers; quantum bits ID COMPUTATION; RESONANCE; SILICON; C-36; C-60 AB Models of encapsulated nuclear spin 1/2 H-1 and P-31 atoms in fullerene and diamond nanocrystal-lite, respectively, are proposed and examined with an ab initio local density functional method for possible applications as single quantum bits (qubits) in solid-state quantum computers. A H-1 atom encapsulated in a fully deuterated fullerene, C20D20, forms the first model system and ab initio calculation shows that the H-1 atom is stable in its atomic state at the center of the fullerene with a barrier of about 1 eV to escape. A P-31 atom positioned at the center of a diamond nanocrystallite is the second model system, and P-31 atom is found to be stable at the substitutional site relative to interstitial sites by 15 eV. Vacancy formation energy is 6 eV in diamond, so the substitutional P-31 atom will be stable against diffusion during the formation mechanisms within the nanocrystallite. The coupling between the nuclear spin and the weakly bound (valance) donor electron in both systems is found to be suitable for single qubit applications, whereas the spatial distributions of (valance) donor electron wave functions are found to be preferentially spread along certain lattice directions, facilitating two or more qubit applications. The feasibility of the fabrication pathways for both model solid-state qubit systems within practical quantum computers is discussed within the context of our proposed solid-state qubits. C1 Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. Stanford Univ, Dept Chem Engn, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Computat Nanotechnol CSC NAS, Moffett Field, CA 94035 USA. RP Srivastava, D (reprint author), Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. NR 23 TC 36 Z9 37 U1 2 U2 7 PU AMER SCIENTIFIC PUBLISHERS PI STEVENSON RANCH PA 25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USA SN 1533-4880 J9 J NANOSCI NANOTECHNO JI J. Nanosci. Nanotechnol. PD MAR PY 2001 VL 1 IS 1 BP 75 EP 81 DI 10.1166/jnn.2001.015 PG 7 WC Chemistry, Multidisciplinary; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Chemistry; Science & Technology - Other Topics; Materials Science; Physics GA 529GH UT WOS:000174291300012 PM 12914035 ER PT J AU Caines, H AF Caines, H CA E896 Collaboration TI An update on the strangeness production measurements and H-0 di-baryon search as performed by the AGS experiment 896 SO JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS LA English DT Article; Proceedings Paper CT 5th International Conference on Strangeness in Quark Matter CY JUL 20-25, 2000 CL UNIV CALIF BERKEKEY, CLARK KERR CAMPUS, BERKELEY, CALIFORNIA HO UNIV CALIF BERKEKEY, CLARK KERR CAMPUS ID H-DIBARYON; COLLISIONS AB E896 was designed to search for the predicted short-lived six-quark Ho dibaryon. The goal is to enhance the existing knowledge by extending the search into regions of shorter lifetimes (approximately half that of the lambda) and via exploring a new creation channel, that of the coalescence of two lambdas. Two main tracking chambers are used, a distributed drift chamber positioned to measure low-p, and high-rapidity neutral particle decay products and a silicon drift detector array which measures particle production at mid-rapidity. Both detectors are also investigating lambda polarization, over their respective coverages, for Au-Au collisions at 11.3 GeV/nucleon. The current status of the Ho di-baryon search and preliminary results of the strange particle production and polarization measurements will be presented. C1 Ohio State Univ, Columbus, OH 43210 USA. Univ Catania, I-95129 Catania, Italy. Wayne State Univ, Detroit, MI 48201 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Space Sci Lab, Berkeley, CA 94720 USA. Rice Univ, Houston, TX 77251 USA. Brookhaven Natl Lab, Upton, NY 11973 USA. Univ Texas, Austin, TX 78712 USA. Univ Calif Los Angeles, Los Angeles, CA 90095 USA. Carnegie Mellon Univ, Pittsburgh, PA 15213 USA. Yale Univ, New Haven, CT USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. Johns Hopkins Univ, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Caines, H (reprint author), Ohio State Univ, Columbus, OH 43210 USA. OI Tricomi, Alessia Rita/0000-0002-5071-5501; TUVE', Cristina/0000-0003-0739-3153 NR 17 TC 8 Z9 8 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0954-3899 J9 J PHYS G NUCL PARTIC JI J. Phys. G-Nucl. Part. Phys. PD MAR PY 2001 VL 27 IS 3 BP 311 EP 318 PG 8 WC Physics, Nuclear; Physics, Particles & Fields SC Physics GA 413XQ UT WOS:000167637200009 ER PT J AU Parusel, ABJ Grimme, S AF Parusel, ABJ Grimme, S TI DFT/MRCI calculations on the excited states of porphyrin, hydroporphyrins, tetrazaporphyrins and metalloporphyrins SO JOURNAL OF PORPHYRINS AND PHTHALOCYANINES LA English DT Article DE quantum mechanical computations; excited states; DFT/MRCI; porphyrin-type systems ID FREE-BASE PORPHIN; DENSITY-FUNCTIONAL THEORY; ELECTRONIC ABSORPTION-SPECTRUM; SAC/SAC-CI METHOD; CONFIGURATION-INTERACTION; SAC-CI; COUPLED-CLUSTER; REDOX REACTIONS; IONIZED STATES; CHLOROPHYLL-A AB A combination of density functional theory and multi-reference configuration interaction methods (DFT/MRCI) has been applied to the calculation of electronic absorption spectra in a series of porphyrin-type molecules. The calculated excitation energies and oscillator strengths for free-base porphyrin (PH2) are in excellent agreement with experiment for both lower and higher excited states which are characterized by a significant contribution of double excitations (>20%). The 4(1)B(2u), 4(1)B(3u), and 5(1)B(2u), states are assigned to the L-band and the 7(1)B(3u) State to the M-band. The results for the hydroporphyrins chlorin (CH2) and bacteriochlorin (BH2) are in agreement with the experimentally observed increase in intensity for the Q-bands relative to PH2. For BH2 we predict a red shift of the Q(x)-band (0.2 eV) and a blue shift of the B-band (0.5-0.7 eV) in comparison to both PH2 and CH2. For porphyrazine (PzH(2)) and the commercial pigment phthalocyanine (PcH2) the calculated oscillator strengths of the Q-and B-bands are of comparable size explaining the intense color of PcH2. For the metalloporphyrins with magnesium (PMg) and zinc (PZn), the x- and y-polarized components of the Q- and B-bands collapse, due to the higher D-4h symmetry of the molecules. The calculations reproduce the slight, experimentally observed increase in the oscillator strength of the Q-band and the decrease for the B-band. These effects are ascribed to the electropositive nature of the metals relative to hydrogen. Except for the Q-bands, which are adequately described by the 'four-orbital model,' it is essential to account for excitations outside the four frontier orbitals as well as double and triple excitations for accurate reproduction of experimental data. We compare our results both with experiment and, where available, recent first-principle SAC-CI, MRMP, and TDDFT calculations. Copyright (C) 2001 John Wiley & Sons, Ltd. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Munster, Inst Organ Chem, D-48149 Munster, Germany. RP Parusel, ABJ (reprint author), Univ Vienna, Inst Theoret Chem & Struct Biol, Althanstr 14, A-1090 Vienna, Austria. RI Grimme, Stefan/B-2873-2010 NR 41 TC 79 Z9 79 U1 3 U2 43 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX PO19 1UD, ENGLAND SN 1088-4246 J9 J PORPHYR PHTHALOCYA JI J. Porphyr. Phthalocyanines PD MAR PY 2001 VL 5 IS 3 BP 225 EP 232 DI 10.1002/jpp.310 PG 8 WC Chemistry, Multidisciplinary SC Chemistry GA 411EB UT WOS:000167484200004 ER PT J AU Plichta, EJ Hendrickson, M Thompson, R Au, G Behl, WK Smart, MC Ratnakumar, BV Surampudi, S AF Plichta, EJ Hendrickson, M Thompson, R Au, G Behl, WK Smart, MC Ratnakumar, BV Surampudi, S TI Development of low temperature Li-ion electrolytes for NASA and DoD applications SO JOURNAL OF POWER SOURCES LA English DT Article; Proceedings Paper CT International Conference on Interfacial Phenomena in Batteries CY DEC 12-15, 1999 CL ROME, ITALY DE lithium-ion batteries; energy storage devices; low temperature electrolytes ID CARBONATES AB Both NASA and the US Army have interest in developing secondary energy storage devices with improved low temperature performance to meet the demanding requirements of space missions and man-portable applications. Lithium-ion systems have been identified as having the most promise due to their high specific energy density and wide operational temperature ranges from the use of organic solvent-based electrolytes, rather than aqueous-based systems, initially, the SOA Lithium-ion technology was limited to operation above -10 degreesC, due primarilly to the fact that the electrolytes employed had high melting points and were highly viscous at low temperatures, resulting in low ionic conductivity. However, due to recent developments in electrolyte formulations at the Army and at JPL, improved low temperature performance of lithium-ion cells have been demonstrated, with efficient cell operation to temperatures as low as -30 degreesC. This was achieved by developing multi-component solvent systems, based on mixtures of cyclic and aliphatic alkyl carbonates. In the course of investigating the viability of a number of advanced electrolyte systems, it was identified that the protective surface films which form on the carbonoceous-based anodes can strongly influence the low temperature capabilities of lithium-ion cells, in addtion to the ionic conductivity of the electrolyte. Thus, in order to optimize an electrolyte for low temperature applications, it is necessary to balance the inherent physical properties of the formulations (i.e. freezing point, viscosity, and ionic conductivity) with the observed compatibility with the chosen cell chemistry (i.e. the nature of the passivating films formed on the electrodes). Published by Elsevier Science B.V. C1 USA, CECOM, RDEC, ARL,AMSEL,RD,C2,AP,BA, Ft Monmouth, NJ 07703 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Plichta, EJ (reprint author), USA, CECOM, RDEC, ARL,AMSEL,RD,C2,AP,BA, Ft Monmouth, NJ 07703 USA. NR 4 TC 48 Z9 56 U1 3 U2 32 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0378-7753 J9 J POWER SOURCES JI J. Power Sources PD MAR 1 PY 2001 VL 94 IS 2 BP 160 EP 162 DI 10.1016/S0378-7753(00)00578-4 PG 3 WC Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary SC Chemistry; Electrochemistry; Energy & Fuels; Materials Science GA 410YY UT WOS:000167469700002 ER PT J AU Melcher, KJ Ibrahim, MB AF Melcher, KJ Ibrahim, MB TI Analysis of a device for generating perturbations in supersonic wind tunnels SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The analytical study of a del;ice called the dual plate disturbance generator is described. This del icr has been proposed as a mechanism for generating gustlike perturbations in supersonic wind tunnels, The device is envisioned as a means to experimentally validate dynamic models and control systems designed for high-speed inlets. The dual plate disturbance generator is composed of two flat trapezoidal plates that modify the properties of the flow ingested by a supersonic inlet. One plate may be oscillated to generate small perturbations in the flow. The other plate is held stationary to maintain a constant angle of attack. Four modes of operation exist; each mode is distinguished by the relative position of the plates and the structure of the resulting flowfield. Design equations and performance maps were developed for one of the four modes of operation using an idealized approach and the compressible flow relations. The maps and equations were then used to design and evaluate a disturbance generator for a 3.05 x 3.05 m (10 x 10 ft) supersonic wind tunnel. Results suggest that, under certain conditions, the proposed device can meet and exceed established gust generator requirements. However, further study is required to identify the optimal mode of operation and establish feasibility. C1 NASA, John H Glenn Res Ctr Lewis Field, Controls & Dynam Technol Branch, Instrumentat & Control Technol Div, Cleveland, OH 44135 USA. Cleveland State Univ, Dept Mech Engn, Cleveland, OH 44115 USA. RP Melcher, KJ (reprint author), NASA, John H Glenn Res Ctr Lewis Field, Controls & Dynam Technol Branch, Instrumentat & Control Technol Div, M-S 77-1,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2001 VL 17 IS 2 BP 270 EP 275 DI 10.2514/2.5773 PG 6 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500007 ER PT J AU Smart, MK AF Smart, MK TI Experimental testing of a hypersonic inlet with rectangular-to-elliptical shape transition SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Wind-tunnel testing of a hypersonic inlet with rectangular-to-elliptical shape transition has been conducted at Mach 6.2. These tests were performed to validate the use of a recently developed design methodology for fixed-geometry hypersonic inlets suitable for airframe integrated scramjets. Results indicated that flow features within the inlet were similar to design and that the inlet typically captured 96% of the available airflow. Typical mass-flow-weighted total pressure recoveries of 55% were obtained for compression ratios of 14.8 throughout the test program. Assessment of the inlet starting characteristics indicated that the inlet self-started at Mach 6.2 despite the fact that it had an internal contraction ratio well above the Kantrowitz limit (Kantrowitz, A,, and Donaldson, C., "Preliminary Investigation of Supersonic Diffusers," NACA WR L-713, 1945). These results demonstrate that high-performance, fixed-geometry inlets can be designed to combine a nearly rectangular capture with a smooth transition to an elliptical throat. C1 NASA, Langley Res Ctr, Lockhead Martin Engn & Sci, Hampton, VA 23681 USA. RP Smart, MK (reprint author), NASA, Langley Res Ctr, Lockhead Martin Engn & Sci, MS 168, Hampton, VA 23681 USA. RI Smart, Michael/C-8823-2013 NR 12 TC 28 Z9 37 U1 2 U2 10 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 MAR-APR PY 2001 VL 17 IS 2 BP 276 EP 283 DI 10.2514/2.5774 PG 8 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500008 ER PT J AU Majdalani, J Roh, TS AF Majdalani, J Roh, TS TI Vorticity dynamics in isobarically closed porous channels part II: Space-reductive perturbations SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/ASME/SAE/ASEE 35th Joint Propulsion Conference and Exhibit CY JUN 20-24, 1999 CL LOS ANGELES, CALIFORNIA SP Amer Inst Aeronaut & Astronaut, ASME, SAE, ASEE ID ACOUSTIC BOUNDARY-LAYER; SOLID-PROPELLANT ROCKET; MOTORS; OSCILLATIONS; COMBUSTION; STABILITY; INJECTION; SCALES; FLOW AB In extending previous work this paper continues to address the acoustico-vortical coupling inside a porous channel of the closed-open type. The companion paper (Majdalani, J,. "Vorticity Dynamics in Isobarically Closed Porous Channels part I: Standard Perturbations:" Journal of Propulsion and Power, Vol, 17, No. 2) applies conventional perturbation principles to derive the temporal vorticity from the linearized vorticity transport equation. Two alternative efforts will be invested here to obtain the temporal velocity from the linearized momentum equation, These efforts rest on applying Wentzel, Kramers, and Brillouin (WKB) and multiple-scale expansions, The multiple-scale approach includes the innovative idea of introducing a virtually arbitrary scale that can be left unspecified during the derivation process. At the conclusion of the asymptotic analysis, this unknown variable is determined. The algebraic complexity of the resulting variable justifies the reverse engineering methodology adopted in its derivation. Its complexity stems from its intrinsic function of singly representing a triple-deck structure of inner, intermediate, and outer length scales. This spatial scale reduction allows a conventional two-variable multiple-scale expansion to be successful, The emerging one-term formulation is conveniently short and accurate. Its simplicity enables us to obtain closed-form expressions for the velocity modulus and depth of penetration. Numerical verifications reveal that the error associated with this space-reductive perturbation solution is smaller than its precursors, namely, the standard perturbation solution of Paper I and the WKB solution furnished here. Most particularly, the asymptotic equations are found to agree very well with independently acquired computational data. The latter are obtained from a two-dimensional Navier-Stokes solver that handles the nonlinear conservation equations. C1 Marquette Univ, Dept Mech & Ind Engn, Milwaukee, WI 53233 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Majdalani, J (reprint author), Marquette Univ, Dept Mech & Ind Engn, Milwaukee, WI 53233 USA. NR 33 TC 9 Z9 9 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2001 VL 17 IS 2 BP 363 EP 370 DI 10.2514/2.5750 PG 8 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500019 ER PT J AU Majumdar, A Steadman, T AF Majumdar, A Steadman, T TI Numerical modeling of pressurization of a propellant tank SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA 37th Aerospace Sciences Meeting and Exhibit CY JAN 11-14, 1999 CL RENO, NEVADA SP Amer Inst Aeronaut & Astronaut AB An unsteady finite volume procedure has been developed to predict the history of pressure, temperature, and mass Row rate of the pressurant and propellant during the expulsion of the propellant from a tank. The time-dependent mass, momentum, entropy, and fluid specie conservation equations are sol,ed at the ullage space. The model accounts fur the change in the ullage volume due to expulsion of the propellant. It also accounts for the heat transfer from the ullage gas to the tank wall and propellant and the mass transfer from the propellant to the ullage pas. The predicted pressure and temperature of the ullage, the temperature of the tank wall, and the pressurant Row rates into the tank during pressurization have been presented for a simple test case. The results of several test cases were compared with a published correlation of pressurant requirements for a given displacement of propellant, The agreement between the predictions and the correlation was found to be satisfactory, Inclusion of mass transfer, in general, improved the comparison between the numerical prediction and the published correlation. C1 Sverdrup Technol Inc, Space Transportat Directorate, Huntsville, AL 35806 USA. RP Majumdar, A (reprint author), NASA, George C Marshall Space Flight Ctr, Thermodynam & Heat Transfer Grp, ED25, Huntsville, AL 35812 USA. NR 6 TC 13 Z9 14 U1 0 U2 6 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 MAR-APR PY 2001 VL 17 IS 2 BP 385 EP 390 DI 10.2514/2.5754 PG 6 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500022 ER PT J AU Shyy, W Tucker, PK Vaidyanathan, R AF Shyy, W Tucker, PK Vaidyanathan, R TI Response surface and neural network techniques for rocket engine injector optimization SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The response surface methodology for rocket engine injector design optimization for which only modest amounts of data may exist is examined. Two main aspects are emphasized: relative performance of quadratic and cubic polynomial response surfaces and enhancement of the fidelity of the response surface via neural networks. A data set of 45 design points from a semi-empirical model for a shear coaxial injector element using gaseous oxygen and gaseous hydrogen propellants is used to formulate response surfaces using quadratic and cubic polynomials. This original data set is also employed to train a two-layered radial basis neural network (RBNN). The trained network is then used to generate additional data to augment the original information available to characterize the design space. Quadratic and cubic polynomials are again used to generate response surfaces for this RBNN-enhanced data set, The response surfaces resulting from both the original and RBNN-enhanced data sets are compared for accuracy. Whereas the cubic fit is superior to the quadratic fit for each data set, the RBNN-enhanced data set is capable of improving the accuracy of the response surface if noticeable errors from polynomial curve fits are encountered. Furthermore, the RBNN-enhanced data set yields more consistent selections of optimal designs between cubic and quadratic polynomials. The techniques de, eloped can be directly applied to injector design and optimization for rocket propulsion. C1 Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. NASA, George C Marshall Space Flight Ctr, Space Transportat Directorate, Huntsville, AL 35812 USA. Univ Florida, Dept Aerosp Engn, Gainesville, FL 32611 USA. RP Shyy, W (reprint author), Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. OI Shyy, Wei/0000-0001-6670-5394 NR 15 TC 9 Z9 14 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2001 VL 17 IS 2 BP 391 EP 401 DI 10.2514/2.5755 PG 11 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500023 ER PT J AU Strakey, PA Talley, DG Hutt, JJ AF Strakey, PA Talley, DG Hutt, JJ TI Mixing characteristics of coaxial injectors at high gas/liquid momentum ratios SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB A study of the spray of a swirl coaxial gas-liquid injector operating at high gas/liquid momentum ratios is reported, Mixing and droplet size characteristics of the swirl injector are also compared to a shear coaxial injector, currently being used in the space shuttle main engine fuel preburner, The injectors were tested at elevated chamber pressures using water as a liquid oxygen simulant and nitrogen and helium as gaseous hydrogen simulants. The elevated chamber pressure allowed for matching of several of the preburner injector conditions including gas/liquid momentum ratio, density ratio, and Mach number. Diagnostic techniques used to characterize the spray included strobe backlight imaging, laser-sheet spray imaging, mechanical patternation, and phase Doppler interferometry. The results indicate that thr radial spreading of the swirl coaxial spray is much less than was reported in previous studies of swirl injectors operating at atmospheric backpressure, The swirl coaxial spray did, however, exhibit a smaller overall droplet size. C1 USAF, Res Lab, Space & Missile Propuls Div, Aerophys Branch PRSA, Edwards AFB, CA 93524 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Strakey, PA (reprint author), USAF, Res Lab, Space & Missile Propuls Div, Aerophys Branch PRSA, 10 E Saturn Blvd, Edwards AFB, CA 93524 USA. NR 22 TC 12 Z9 13 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2001 VL 17 IS 2 BP 402 EP 410 DI 10.2514/2.5756 PG 9 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500024 ER PT J AU Foster, JE Patterson, MJ AF Foster, JE Patterson, MJ TI Internal plasma properties and enhanced performance of 8-centimeter ion thruster discharge SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB There is a need for a lightweight, low-pow er ion thruster for space science missions. Such an ion thruster is under development. In an effort to better understand the discharge performance of this thruster, a version of this thruster with an anode containing electrically isolated electrodes at the cusps was fabricated and tested. Discharge characteristics of this ring cusp ion thruster were measured without ion beam extraction, Discharge current was measured at collection electrodes located at the cusps and at the anode body itself. Discharge performance and plasma properties were measured as a function of discharge power, which was varied between 20 and 50 W, It was found that ion production costs decreased by as much as 20% when the two most-downstream cusp electrodes were allowed to Boat. Floating the electrodes did not give rise to a significant increase in discharge power even though the plasma density increased markedly. The improved performance is attributed to enhanced electron containment. C1 NASA, John H Glenn Res Ctr Lewis Field, Onboard Propuls & Power, Cleveland, OH 44135 USA. RP Foster, JE (reprint author), NASA, John H Glenn Res Ctr Lewis Field, Onboard Propuls & Power, MS 301-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 17 TC 2 Z9 2 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2001 VL 17 IS 2 BP 428 EP 432 DI 10.2514/2.5759 PG 5 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500027 ER PT J AU Stallard, BW Hooper, EB Power, JL AF Stallard, BW Hooper, EB Power, JL TI Plasma confinement in the whistler wave plasma thruster SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID ELECTRIC PROPULSION; RESONANCE AB Plasma thruster experiments using whistler wave plasma heating of electrons have shown large increases in the operating density and the plasma potential providing for ion acceleration when the edge potential was controlled through use of electrically floating electrodes at the plasma edge. Analysis of these results show that E x B (vector cross product) drifts within the radial electric field in the small diameter plasma column dominated the ion confinement and power balance. Measurements of a density increase at higher magnetic field are consistent with the predictions of ion orbit analysis. Device modifications to improve thruster performance are discussed. C1 Lawrence Livermore Natl Lab, Laser Directorate, Livermore, CA 94551 USA. NASA, John H Glenn Res Ctr Lewis Field, Board Propuls Branch, Cleveland, OH 44135 USA. RP Stallard, BW (reprint author), Lawrence Livermore Natl Lab, Laser Directorate, Box 808,L-637, Livermore, CA 94551 USA. NR 17 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2001 VL 17 IS 2 BP 433 EP 440 DI 10.2514/2.5760 PG 8 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500028 ER PT J AU Koch, PJ Probasco, DP Wolff, JM Copenhaver, WW AF Koch, PJ Probasco, DP Wolff, JM Copenhaver, WW TI Transonic compressor influences on upstream surface pressures with axial spacing SO JOURNAL OF PROPULSION AND POWER LA English DT Article C1 Wright State Univ, Dept Mech & Mat Engn, Dayton, OH 45435 USA. USAF, Res Lab, Propuls Directorate, Turbine Engine Div, Wright Patterson AFB, OH 45433 USA. NASA, Lewis Res Ctr, Res & Technol Directorate, Turbomachinery & Propuls Syst Div, Cleveland, OH 44135 USA. RP Koch, PJ (reprint author), Wright State Univ, Dept Mech & Mat Engn, Dayton, OH 45435 USA. NR 1 TC 2 Z9 2 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2001 VL 17 IS 2 BP 474 EP 476 DI 10.2514/2.5768 PG 3 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500035 ER PT J AU Litchford, RJ Cole, JW Bityurin, VA Lineberry, JT AF Litchford, RJ Cole, JW Bityurin, VA Lineberry, JT TI Thermodynamic cycle analysis of magnetohydrodynamic-bypass hypersonic airbreathing engines SO JOURNAL OF PROPULSION AND POWER LA English DT Article C1 NASA, George C Marshall Space Flight Ctr, Adv Space Transportat Program, Huntsville, AL 35812 USA. Russian Acad Sci, Inst High Temp, IVTAN, Magnetohydrodynam Div,Int Magnetohydrodynam Progr, Moscow, Russia. LyTec LLC, Tullahoma, TN 37388 USA. RP Litchford, RJ (reprint author), NASA, George C Marshall Space Flight Ctr, Adv Space Transportat Program, TD 15, Huntsville, AL 35812 USA. NR 14 TC 6 Z9 13 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 2001 VL 17 IS 2 BP 477 EP 480 DI 10.2514/2.5769 PG 4 WC Engineering, Aerospace SC Engineering GA 411TZ UT WOS:000167516500036 ER PT J AU Parmenter, KE Shuman, K Milstein, F Szalai, CE Tran, HK Rasky, DJ AF Parmenter, KE Shuman, K Milstein, F Szalai, CE Tran, HK Rasky, DJ TI Compressive response of lightweight ceramic ablators: Phenolic impregnated carbon ablator SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID GAS-PERMEABILITY AB Lightweight ceramic ablators are porous fibrous ceramic substrates impregnated with organic resins, The materials were developed for use as heat shields for planetary entry. The compressive response and hardness of a phenolic impregnated carbon ablator and its fibrous substrates are reported. Results are also given for charred specimens of the ablator, Fibers in the substrate tend to be randomly and uniformly aligned parallel to a preferred plane. Two characteristic compressive responses were observed, depending on the orientation of the load with respect to the preferred fiber-alignment plane. When the load was parallel to this plane, the stress increased approximately linearly with increasing strain to strains of about 2%, The stress then followed an erratic "horizontal" path with increasing strain as the materials apparently failed by an internal separation and buckling mechanism, In contrast, during compression transverse to the fiber-alignment plane, the materials underwent significant, nonlinear, plastic deformation, wherein the stress increased with increasing strain to strains of over 50% without indications of fracture. Considerable energy was absorbed during compression, particularly for materials subjected to the transverse loading condition. Resin impregnation substantially strengthens the ablator material; this effect was prominent for specimens loaded transverse to the fiber-alignment plane. C1 Univ Calif Santa Barbara, Dept Mech Engn & Mat, Santa Barbara, CA 93106 USA. NASA, Ames Res Ctr, Thermal Protect Mat & Syst Branch, Moffett Field, CA 94035 USA. RP Parmenter, KE (reprint author), Univ Calif Santa Barbara, Dept Mech Engn & Mat, Santa Barbara, CA 93106 USA. NR 11 TC 9 Z9 9 U1 2 U2 13 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 MAR-APR PY 2001 VL 38 IS 2 BP 231 EP 236 DI 10.2514/2.3675 PG 6 WC Engineering, Aerospace SC Engineering GA 421VA UT WOS:000168083200015 ER PT J AU Alexander, RA Coleman, HW AF Alexander, RA Coleman, HW TI Thermal characterization of a direct gain solar thermal engine SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article C1 NASA, Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Univ Alabama, Prop Res Ctr, Dept Mech & Aerosp Engn, Huntsville, AL 35899 USA. RP Alexander, RA (reprint author), NASA, Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NR 4 TC 0 Z9 0 U1 1 U2 1 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 MAR-APR PY 2001 VL 38 IS 2 BP 287 EP 289 DI 10.2514/2.3683 PG 3 WC Engineering, Aerospace SC Engineering GA 421VA UT WOS:000168083200022 ER PT J AU Rasky, DJ Milos, FS Squire, TH AF Rasky, DJ Milos, FS Squire, TH TI Thermal protection system materials and costs for future reusable launch vehicles SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, Thermal Protect Mat & Syst Branch, Moffett Field, CA 94035 USA. RP Rasky, DJ (reprint author), NASA, Ames Res Ctr, Space Technol Div, MS 229-3, Moffett Field, CA 94035 USA. NR 15 TC 7 Z9 10 U1 0 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 2001 VL 38 IS 2 BP 294 EP 296 DI 10.2514/2.3686 PG 3 WC Engineering, Aerospace SC Engineering GA 421VA UT WOS:000168083200025 ER PT J AU Bergmann, U Glatzel, P Robblee, JH Messinger, J Fernandez, C Cinco, R Visser, H McFarlane, K Bellacchio, E Pizarro, S Sauer, K Yachandra, VK Klein, MP Cox, BL Nealson, KH Cramer, SP AF Bergmann, U Glatzel, P Robblee, JH Messinger, J Fernandez, C Cinco, R Visser, H McFarlane, K Bellacchio, E Pizarro, S Sauer, K Yachandra, VK Klein, MP Cox, BL Nealson, KH Cramer, SP TI High-resolution X-ray spectroscopy of rare events: a different look at local structure and chemistry SO JOURNAL OF SYNCHROTRON RADIATION LA English DT Article; Proceedings Paper CT 11th International Conference on X-ray Absorption Fine Structure (XAFS XI) CY JUL 26-31, 2000 CL AKO, JAPAN DE X-ray fluorescence spectroscopy; X-ray Raman scattering; inelastic scattering; high resolution; metalloproteins ID OXYGEN-EVOLVING COMPLEX; MANGANESE CLUSTER; FLUORESCENCE SPECTROSCOPY; RAMAN-SPECTROSCOPY; OXIDATION-STATES; PHOTOSYSTEM-II; SENSITIVITY; WATER; TRANSITIONS; DEPENDENCE AB The combination of large-acceptance high-resolution X-ray optics with bright synchrotron sources permits quantitative analysis of rare events such as X-ray fluorescence from very dilute systems, weak fluorescence transitions or X-ray Raman scattering. Transition-metal K beta fluorescence contains information about spin and oxidation state; examples of the characterization of the Mn oxidation states in the oxygen-evolving complex of photosystem II and Mn-consuming spores from the marine bacillus SG-1 are presented. Weaker features of the K beta spectrum resulting from valence-level and 'interatomic' ligand to metal transitions contain detailed information on the ligand-atom type, distance and orientation. Applications of this spectral region to characterize the local structure of model compounds are presented. X-ray Raman scattering (XRS) is an extremely rare event, but also represents a unique technique to obtain bulk-sensitive low-energy (<600 eV) X-ray absorption fine structure (XAFS) spectra using hard ( 10 keV) X-rays. A photon is inelastically scattered, losing part of its energy to promote an electron into an unoccupied level. In many cases, the cross section is proportional to that of the corresponding absorption process yielding the same X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) features. XRS finds application for systems that defy XAFS analysis at low energies, e.g. liquids or highly concentrated complex systems, reactive compounds and samples under extreme conditions (pressure, temperature). Recent results are discussed. C1 Univ Calif Berkeley, Lawrence Berkeley Lab, Phys Biosci Div, Berkeley, CA 94720 USA. Univ Calif Davis, Dept Appl Sci, Davis, CA 95616 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Bergmann, U (reprint author), Univ Calif Berkeley, Lawrence Berkeley Lab, Phys Biosci Div, Berkeley, CA 94720 USA. RI Fernandez, Carmen/C-9546-2012; Glatzel, Pieter/E-9958-2010; Institute of Chemistry - USP, Dept. of Chemistry/B-8988-2012 OI Fernandez, Carmen/0000-0003-2201-6241; Glatzel, Pieter/0000-0001-6532-8144; FU NIGMS NIH HHS [GM 55302, GM-48145, R01 GM055302, R56 GM055302] NR 39 TC 27 Z9 28 U1 1 U2 21 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0909-0495 J9 J SYNCHROTRON RADIAT JI J. Synchrot. Radiat. PD MAR PY 2001 VL 8 BP 199 EP 203 DI 10.1107/S0909049500016484 PN 2 PG 5 WC Instruments & Instrumentation; Optics; Physics, Applied SC Instruments & Instrumentation; Optics; Physics GA 407YC UT WOS:000167298100033 PM 11512725 ER PT J AU Kemner, KM Kelly, SD Orlandini, KA Tsapin, AI Goldfeld, MG Perfiliev, YD Nealson, KH AF Kemner, KM Kelly, SD Orlandini, KA Tsapin, AI Goldfeld, MG Perfiliev, YD Nealson, KH TI XAS investigations of Fe(VI) SO JOURNAL OF SYNCHROTRON RADIATION LA English DT Article; Proceedings Paper CT 11th International Conference on X-ray Absorption Fine Structure (XAFS XI) CY JUL 26-31, 2000 CL AKO, JAPAN DE astrobiology; biosignature; biogeochemistry; environmental science; XAFS ID ABSORPTION FINE-STRUCTURE; SPECTRA AB Recent attention has been given to a reexamination of results from the early Viking missions to Mars that suggested the presence of one or more strong oxidants in Martian soil. Since Fe is one of the main constituents of the Martian surface and Fe( VI) is known to be a highly reactive, strong oxidant, we have made XANES and EXAFS measurements of Fe( II), Fe( III), Fe( IV), and Fe( VI) in solid and solution forms. Results from these studies indicate a preedge XANES feature from Fe( VI) samples similar to that commonly seen from Cr( VI) samples. Results of first shell analysis indicate a linear relationship between the Fe-O bondlength and Fe valence state. C1 Argonne Natl Lab, Argonne, IL 60439 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Moscow MV Lomonosov State Univ, Sch Chem, Moscow, Russia. RP Kemner, KM (reprint author), Argonne Natl Lab, 9700 S Cass Ave, Argonne, IL 60439 USA. EM kemner@anl.gov RI ID, MRCAT/G-7586-2011 NR 16 TC 10 Z9 10 U1 1 U2 5 PU INT UNION CRYSTALLOGRAPHY PI CHESTER PA 2 ABBEY SQ, CHESTER, CH1 2HU, ENGLAND SN 1600-5775 J9 J SYNCHROTRON RADIAT JI J. Synchrot. Radiat. PD MAR PY 2001 VL 8 BP 949 EP 951 DI 10.1107/S0909049500021026 PN 2 PG 3 WC Instruments & Instrumentation; Optics; Physics, Applied SC Instruments & Instrumentation; Optics; Physics GA 407YC UT WOS:000167298100287 PM 11512989 ER PT J AU Zhu, S Su, CH Lehozeky, SL AF Zhu, S Su, CH Lehozeky, SL TI Gravity-related transport in reactive off-axis sputtering deposition? SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article ID THIN-FILMS; GROWTH AB An experiment was performed to investigate the transport characterization of reactive off-axis sputtering deposition. Due to the collision and/or thermalization process between the sputtered species and background gases, three transport regions were observed when the growth pressures were varied from 5 to 150 mTorr. A gravity-related phenomenon was revealed in film growth at relatively high growth pressures by measuring film growth rate at two depositing orientations, which was either parallel or perpendicular to the gravity vector. In this study, possible design for the substrate holder orientation in the off-axis sputtering system was also suggested. (C) 2001 American Vacuum Society. C1 NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Sci Directorate, Huntsville, AL 35812 USA. RP Zhu, S (reprint author), NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, SD47, Huntsville, AL 35812 USA. NR 7 TC 0 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD MAR-APR PY 2001 VL 19 IS 2 BP 697 EP 699 DI 10.1116/1.1347052 PG 3 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA 413CD UT WOS:000167591600048 ER PT J AU Shen, YX Homaifar, A AF Shen, YX Homaifar, A TI Vibration control of flexible structures with PZT sensors and actuators SO JOURNAL OF VIBRATION AND CONTROL LA English DT Article DE modeling; active vibration control; fuzzy logic; genetic algorithms; optimal control; robust control AB In this paper, a two-degree-of-freedom model has been constructed for a structural dynamic system consisting of a linear elastic plate bonded with piezoelectric sensors and actuators. A multivariable feedback controller is designed. Four control procedures based on the minimization of performance output error and the quadratic performance index have been developed that use rate-feedback control, hybrid fuzzy-PID control, genetic algorithms-designed PID control, and linear quadratic Gaussian/loop transfer recovery control methods. Here, the genetic algorithm fitness function is approximately proportional to the inverse of the output error. To test these control techniques in an efficient and systematic way, we built a digital control system that consists of MATLAB/SIMULINK (modeling software and a dSPACE DS 2100 controller in a personal computer. The real-time experiment and off-line simulation results confirm that these four kinds of control methods are reliable and efficient in suppression of the steady-state resonance vibrations. C1 N Carolina Agr & Tech State Univ, Dept Elect Engn, NASA, Ctr Aerosp Res, Greensboro, NC 27411 USA. RP Shen, YX (reprint author), N Carolina Agr & Tech State Univ, Dept Elect Engn, NASA, Ctr Aerosp Res, Greensboro, NC 27411 USA. NR 16 TC 30 Z9 30 U1 0 U2 11 PU SAGE PUBLICATIONS LTD PI LONDON PA 1 OLIVERS YARD, 55 CITY ROAD, LONDON EC1Y 1SP, ENGLAND SN 1077-5463 J9 J VIB CONTROL JI J. Vib. Control PD MAR PY 2001 VL 7 IS 3 BP 417 EP 451 DI 10.1177/107754630100700306 PG 35 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 416MX UT WOS:000167785700006 ER PT J AU McGill, M Rallison, R AF McGill, M Rallison, R TI Holographic optics convert rings to points for detection SO LASER FOCUS WORLD LA English DT Article AB A novel holographic optical element designed by NASA allows use of a linear array detector to record the fringe pattern of a Fabry-Perot. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ralcon Dev Lab, Paradise, UT 84328 USA. RP McGill, M (reprint author), NASA, Goddard Space Flight Ctr, Code 912, Greenbelt, MD 20771 USA. RI McGill, Matthew/D-8176-2012 NR 2 TC 2 Z9 2 U1 0 U2 0 PU PENNWELL PUBL CO PI NASHUA PA 98 SPIT BROOK RD, NASHUA, NH 03062-2801 USA SN 0740-2511 J9 LASER FOCUS WORLD JI Laser Focus World PD MAR PY 2001 VL 37 IS 3 BP 131 EP + PG 4 WC Optics SC Optics GA 414FW UT WOS:000167656300033 ER PT J AU Carls, MG Babcock, MM Harris, PM Irvine, GV Cusick, JA Rice, SD AF Carls, MG Babcock, MM Harris, PM Irvine, GV Cusick, JA Rice, SD TI Persistence of oiling in mussel beds after the Exxon Valdez oil spill SO MARINE ENVIRONMENTAL RESEARCH LA English DT Article DE mussels; Mytilus trossulus; Prince William Sound; Gulf of Alaska; Exxon Valdez; petroleum hydrocarbons; oil spills; monitoring ID PRINCE-WILLIAM-SOUND; WEATHERED CRUDE-OIL; AROMATIC-COMPOUNDS; FISH EMBRYOS; SEDIMENTS; HYDROCARBONS; EXPOSURE; SENSITIVITY; MORTALITY; MAMMALS AB Persistence and weathering of Exxon Valdez oil in intertidal mussel (Mytilus trossulus) beds in Prince William Sound (PWS) and along the Gulf of Alaska was monitored from 1992 to 1995. Beds with significant contamination included most previously oiled areas in PWS, particularly within the Knight Island group and the Kenai Peninsula. In sediments, yearly mean concentrations of total petroleum hydrocarbons ranged from < 60 g/g in reference beds to 62,258 mug/g wet wt., or approximately 0 to 523 mug/g dry wt. total polynuclear aromatic hydrocarbons (TPAHs). In mussels, mean TPAH concentrations ranged up to 8.1 mug/g dry wt. Hydrocarbon concentrations declined significantly with time in some, but not all mussels and sediments, and should reach background levels within three decades of the spill in most beds. In 1995, mean hydrocarbon concentration was greater than twice background concentration in sediments from 27 of 34 sites, and in mussels from 18 of 31 sites. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Natl Marine Fisheries Serv, Auke Bay Lab, Juneau, AK 99801 USA. Natl Biol Serv, Alaska Sci Ctr, Anchorage, AK 99503 USA. Natl Pk Serv, Anchorage, AK 99503 USA. RP Carls, MG (reprint author), Natl Marine Fisheries Serv, Auke Bay Lab, 11305 Glacier Highway, Juneau, AK 99801 USA. NR 32 TC 65 Z9 68 U1 1 U2 17 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0141-1136 J9 MAR ENVIRON RES JI Mar. Environ. Res. PD MAR PY 2001 VL 51 IS 2 BP 167 EP 190 DI 10.1016/S0141-1136(00)00103-3 PG 24 WC Environmental Sciences; Marine & Freshwater Biology; Toxicology SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Toxicology GA 389LX UT WOS:000166240300005 PM 11468815 ER PT J AU Miyoshi, K Wu, RLC AF Miyoshi, K Wu, RLC TI Measurements and diagnostics of diamond films and coatings SO MEASUREMENT LA English DT Article DE measurement; diagnostic methodology; chemical-vapor-deposited (CVD) diamond; films and coatings ID FRICTION; WEAR AB The commercial potential of chemical-vapor-deposited (CVD) diamond films has been established and a number of applications have been identified through university, industry, and government research studies. This paper discusses the methodologies used for property measurement and diagnostic of CVD diamond films and coatings. Measurement and diagnostic techniques studied include scanning electron microscopy, transmission electron microscopy, atomic force microscopy, stylus profilometry, X-ray diffraction, electron diffraction, Raman spectroscopy, Rutherford backscattering, elastic recoil spectroscopy, and friction examination. Each measurement and diagnostic technique provides unique information. A combination of techniques can provide the technical information required to understand the quality and properties of CVD diamond films, which are important to their application in specific component systems and environments. In this study the combination of measurement and diagnostic techniques was successfully applied to correlate deposition parameters and resultant diamond film composition, crystallinity, grain size, surface roughness, and coefficient of friction. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. K Syst Corp, Beavercreek, OH 45432 USA. RP NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. EM miyoshi@grc.nasa.gov NR 27 TC 7 Z9 7 U1 0 U2 2 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0263-2241 EI 1873-412X J9 MEASUREMENT JI Measurement PD MAR PY 2001 VL 29 IS 2 BP 113 EP 126 DI 10.1016/S0263-2241(00)00032-4 PG 14 WC Engineering, Multidisciplinary; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 423RL UT WOS:000168190600004 ER PT J AU Lind, R Snyder, K Brenner, M AF Lind, R Snyder, K Brenner, M TI Wavelet analysis to characterise non-linearities and predict limit cycles of an aeroelastic system SO MECHANICAL SYSTEMS AND SIGNAL PROCESSING LA English DT Article ID NONLINEAR-SYSTEMS AB Non-linear dynamics in aeroelastic systems are difficult to analyse and can induce unpredicted limit cycle oscillations in flight. This paper introduces wavelet analysis for processing flight data to extract information about structural non-linearities. Features and trends from wavelet transform maps of transient responses are used to detect and characterise polynomial non-linearities in stiffness. These Features are also used to formulate functions that use transient responses at stable flight conditions to predict the onset of limit-cycle oscillations. (C) 2001 Academic Press. C1 NASA, Dryden Flight Res Ctr, Edwards, CA 93523 USA. RP Lind, R (reprint author), NASA, Dryden Flight Res Ctr, MS 4840, Edwards, CA 93523 USA. NR 25 TC 14 Z9 15 U1 0 U2 0 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 MAR PY 2001 VL 15 IS 2 BP 337 EP 356 DI 10.1006/mssp.2000.1346 PG 20 WC Engineering, Mechanical SC Engineering GA 428UM UT WOS:000168479800008 ER PT J AU Bernstein, MP Dworkin, JP Sandford, SA Allamandola, LJ AF Bernstein, MP Dworkin, JP Sandford, SA Allamandola, LJ TI Ultraviolet irradiation of naphthalene in H(2)O ice: Implications for meteorites and biogenesis SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID POLYCYCLIC AROMATIC-HYDROCARBONS; INTERPLANETARY DUST PARTICLES; LASER MASS-SPECTROMETRY; EARLY SOLAR-SYSTEM; ORGANIC-COMPOUNDS; ASTROPHYSICAL IMPLICATIONS; CARBONACEOUS CHONDRITES; MURCHISON METEORITE; INFRARED-EMISSION; UV-RADIATION AB The polycyclic aromatic hydrocarbon (PAH) naphthalene was exposed to ultraviolet radiation in H(2)O ice under astrophysical conditions, and the products were analyzed using infrared spectroscopy and high-performance liquid chromatography. As we found in our earlier studies on the photoprocessing of coronene in H(2)O ice, aromatic alcohols and ketones (quinones) were formed. The regiochemistry of the reactions is described and leads to specific predictions of the relative abundances of various oxidized naphthalenes that should exist in meteorites if interstellar ice photochemistry influenced their aromatic inventory. Since oxidized PAHs are present in carbon-rich meteorites and interplanetary dust particles (IDPs), and ubiquitous in and fundamental to biochemistry, the delivery of such extraterrestrial molecules to the early Earth may have played a role in the origin and evolution of life. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mountain View, CA 94043 USA. RP Sandford, SA (reprint author), NASA, Ames Res Ctr, Mail Stop 245-6, Moffett Field, CA 94035 USA. EM ssandford@mail.arc.nasa.gov RI Dworkin, Jason/C-9417-2012 OI Dworkin, Jason/0000-0002-3961-8997 NR 47 TC 52 Z9 54 U1 0 U2 8 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 MAR PY 2001 VL 36 IS 3 BP 351 EP 358 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 417JQ UT WOS:000167832200004 ER PT J AU Morbidelli, A Petit, JM Gladman, B Chambers, J AF Morbidelli, A Petit, JM Gladman, B Chambers, J TI A plausible cause of the late heavy bombardment SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID MAIN-BELT; TERRESTRIAL PLANETS; DYNAMICAL LIFETIMES; CLOSE ENCOUNTERS; RUNAWAY GROWTH; ASTEROID BELT; SOLAR-SYSTEM; PLANETESIMALS; EVOLUTION; COMETS AB We show that at the end of the main accretional period of the terrestrial planets, a few percent of the initial planetesimal population in the 1-2 AU zone is left on highly-inclined orbits in the inner solar system. The final depletion of this leftover population would cause an extended bombardment of all of the terrestrial planets, slowly decaying with a timescale on the order of 60 Ma. Because of the large impact velocities dictated by the high inclinations, these projectiles would produce craters much larger than those formed by asteroids of equal size on typical current near-Earth asteroid orbits: on the Moon, basins could have been formed by bodies as small as 20 km in diameter, and 10 km craters could be produced by 400 m impacters. To account for the observed lunar crater record, the initial population of highly-inclined leftovers would need to be a few times that presently in the main asteroid belt, at all sizes, in agreement with the simulations of the primordial sculpting of both these populations. Ifa terminal lunar cataclysm (a spike in the crater record similar to3.9 Ga ago) really occurred on the Moon, it was not caused by the highly-inclined leftover population, because of the monotonic decay of the latter. C1 Observ Cote Azur, F-06304 Nice, France. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Morbidelli, A (reprint author), Observ Cote Azur, BP 4229, F-06304 Nice, France. NR 58 TC 49 Z9 49 U1 0 U2 10 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD MAR PY 2001 VL 36 IS 3 BP 371 EP 380 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 417JQ UT WOS:000167832200006 ER PT J AU Chambers, JE Wetherill, GW AF Chambers, JE Wetherill, GW TI Planets in the asteroid belt SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID SOLAR NEBULA; ORBITAL EVOLUTION; GIANT PLANETS; ACCRETION; PLANETESIMALS; DISK; RESONANCES; EMBRYOS; SYSTEM; GAS AB The main asteroid belt has lost >99.9% of its solid mass since the time at which the planets were forming, according to models for the protoplanetary nebula. Here we show that the primordial asteroid belt could have been cleared efficiently if much of the original mass accreted to form planet-sized bodies, which were capable of perturbing one another into unstable orbits. We provide results from 25 N-body integrations of up to 200 planets in the asteroid belt, with individual masses in the range 0.017-0.33 Earth masses. In the simulations, these bodies undergo repeated close encounters which scatter one another into unstable resonances with the giant planets, leading to collision with the Sun or ejection from the solar system. In response, the giant planets' orbits migrate radially and become more circular. This reduces the size of the main-belt resonances and the clearing rate, although clearing continues. If similar to3 Earth masses of material was removed from the belt this way, Jupiter and Saturn would initially have had orbital eccentricities almost twice their current values. Such orbits would have made Jupiter and Saturn 10-100x more effective at clearing material from the belt than they are on their current orbits. The time required to remove 90% of the initial mass from the belt depends sensitively on the giant planets' orbits, and weakly on the masses of the asteroidal planets. 18 of the 25 simulations end with no planets left in the belt, and the clearing takes up to several hundred million years. Typically, the last one or two asteroidal planets are removed by interactions with planets in the terrestrial region. C1 Armagh Observ, Armagh BT61 9DG, North Ireland. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. RP Chambers, JE (reprint author), Armagh Observ, Armagh BT61 9DG, North Ireland. NR 23 TC 87 Z9 87 U1 0 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 MAR PY 2001 VL 36 IS 3 BP 381 EP 399 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 417JQ UT WOS:000167832200007 ER PT J AU Mittlefehldt, DW Lindstrom, MM AF Mittlefehldt, DW Lindstrom, MM TI Petrology and geochemistry of Patuxent Range 91501, a clast-poor impact melt from the L-chondrite parent body and Lewis Cliff 88663, an L7 chondrite SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID COLLECTION; BODIES; ORIGIN; CHICO; CITY; AGE AB We have performed petrologic and geochemical studies of Patuxent Range (PAT) 91501 and Lewis Cliff (LEW) 88663. PAT 91501, originally classified as an L7 chondrite, is rather a unique, near total impact melt from the L-chondrite parent body. Lewis Cliff 88663 was originally classified as an "achondrite (?)", but we find that it is a very weakly shocked L7 chondrite. PAT 91501 is an unshocked, homogeneous, igneous-textured ultramafic rock composed of euhedral to subhedral olivine, low-Ca pyroxene, augite and chrome-rich spinels with interstitial albitic plagioclase and minor silica-alumina-alkali-rich glass. Only similar to 10% relic chondritic material is present. Olivine grains are homogeneous (Fa(25.2-26.8)) Low-Ca pyroxene (Wo(1.9-7.2)En(71.9-78.2)Fs(19.9-20.9)) and augite (Wo(29.8-39.0)En(49.2-55.3)FS(11.8-14.9)) display a strong linear TiO2-Al2O3 correlation resulting from igneous fractionation. Plagioclase is variable in composition; Or(3.0-7.7)Ab(79.8-84.1)An(8.2-17.2) Chrome-rich spinels are variable in composition and zoned from Cr-rich cores to Ti-Al-rich rims. Some have evolved compositions with up to 7.9 wt% TiO2 PAT 91501 bulk silicate has an L-chondrite lithophile element composition except for depletions in Zn and Br. Siderophile and chalcophile elements are highly depleted due to sequestration in centimeter-size metal-troilite nodules. The minerals in LEW 88663 are more uniform in composition than those in PAT 91501. Olivine grains have low CaO and Cr2O3 contents similar to those in L5-6 chondrites. Pyroxenes have high TiO2 contents with only a diffuse TiO2-Al2O3 correlation. Low-Ca pyroxenes are less calcic (Wo(1.6-3.1)En(76.5-77.0)FS(20.4-21.4)), while augites (Wo(39.5-45.6)En(46.8-51.1)Fs(7.6-9.4)) and plagioclases (Or(2.6-5.7)Ab(74.1-83.1)An(11.2-23.3)) are more calcic. Spinels are homogeneous and compositionally similar to those in L6 chondrites. LEW 88663 has an L-chondrite bulk composition for lithophile elements, and only slight depletions in siderophile and chalcophile elements that are plausibly due to weathering and/or sample heterogeneity. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin SO, Houston, TX 77058 USA. RP Mittlefehldt, DW (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code SN2, Houston, TX 77058 USA. NR 40 TC 37 Z9 39 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 MAR PY 2001 VL 36 IS 3 BP 439 EP 457 PG 19 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 417JQ UT WOS:000167832200011 ER PT J AU Giauque, PH Cherry, HB Nicolet, MA AF Giauque, PH Cherry, HB Nicolet, MA TI Thermal stability of amorphous Ti3Si1O8 thin films SO MICROELECTRONIC ENGINEERING LA English DT Article; Proceedings Paper CT 4th European Workshop on Materials for Advanced Metallization CY FEB 28-MAR 01, 2000 CL STRESA, ITALY DE thin films; amorphous; sputtering; optical coatings; ternary oxides ID TIO2-SIO2 MIXED FILMS; DIFFUSION-BARRIERS; METALLIZATIONS; SILICON; TA AB Films (220 nm-thick) deposited by reactive rf sputtering from a Ti3Si target with an argon/oxygen gas mixture were annealed for 30 min in vacuum at temperatures between 400 and 900 degreesC. The films were characterized by 2 MeV He2+. backscattering spectrometry and X-ray diffraction to monitor thermally induced changes. As-deposited, the films are X-ray-amorphous. First signs of crystallization appear at 600 degreesC. Their composition remains constant and uniform throughout that temperature range, except for the loss of argon that is initially present in the film at a concentration of about 1 at.% and that fully escapes within 5 min at 650 degreesC. Films without silicon obtained from a pure titanium target by reactive rf sputtering with oxygen and of a composition of Ti1O2 are also X-ray-amorphous but crystallize much more readily. The significance of these results is discussed relative to other ternary films of analogous compositions that also tend to form highly stable amorphous or near-amorphous phases ('mictamict' alloys). (C) 2001 Elsevier Science B.V. All rights reserved. C1 CALTECH, Pasadena, CA 91125 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Giauque, PH (reprint author), CALTECH, Pasadena, CA 91125 USA. NR 13 TC 9 Z9 9 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-9317 J9 MICROELECTRON ENG JI Microelectron. Eng. PD MAR PY 2001 VL 55 IS 1-4 BP 183 EP 188 DI 10.1016/S0167-9317(00)00446-9 PG 6 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Optics; Physics, Applied SC Engineering; Science & Technology - Other Topics; Optics; Physics GA 417BP UT WOS:000167815800026 ER PT J AU Cherry, HB Giauque, PH Nicolet, MA AF Cherry, HB Giauque, PH Nicolet, MA TI Stability of conducting amorphous Ru-Si-O thin films under oxygen annealing SO MICROELECTRONIC ENGINEERING LA English DT Article; Proceedings Paper CT 4th European Workshop on Materials for Advanced Metallization CY FEB 28-MAR 01, 2000 CL STRESA, ITALY DE thin film; amorphous; ternary oxide; crystallization; oxygen influence AB Ru1Si1O4 thin films were deposited on Si and oxidized Si substrates by reactive rf magnetron sputtering of an Ru1Si1 target in an argon/oxygen gas mixture. Two MeV He2+ backscattering spectrometry, four-point probe measurements and X-ray diffraction techniques were applied to study the films annealed at 700 degreesC in 100% dry oxygen at pressures from 0.2 to 760 Torr. The as-deposited films are 180 nm thick, X-ray amorphous and have a thickness normalized sheet resistance similar to3 m Omega cm. After 5 min of annealing at 700 degreesC all films show some crystallization of RuO2. Above an annealing pressure of 8 Torr RuO2 crystals an clearly visible by optical microscopy. The temporal evolution investigated below 0.4 Torr shows that the film resistivity drops by one half within the first 5 min. Beyond that both the normalized sheet resistance and the fine-grain structure change little, if at all, for durations up to 4 h. No changes in film composition were detectable by backscattering spectrometry. Films grown on Si (111) vs, oxidized Si (100) substrates evolve identically, but an interfacial layer develops between the Ru1Si1O4 film and the Si (111) substrate within the first 5 min of annealing which electrically decouples the film from the substrate. (C) 2001 Published by Elsevier Science B.V. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH, Pasadena, CA 91125 USA. RP Cherry, HB (reprint author), CALTECH, Jet Prop Lab, MS 303-308,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 3 Z9 3 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-9317 J9 MICROELECTRON ENG JI Microelectron. Eng. PD MAR PY 2001 VL 55 IS 1-4 BP 403 EP 408 DI 10.1016/S0167-9317(00)00474-3 PG 6 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Optics; Physics, Applied SC Engineering; Science & Technology - Other Topics; Optics; Physics GA 417BP UT WOS:000167815800054 ER PT J AU Hartman, PS Hlavacek, A Wilde, H Lewicki, D Schubert, W Kern, RG Kazarians, GA Benton, EV Benton, ER Nelson, GA AF Hartman, PS Hlavacek, A Wilde, H Lewicki, D Schubert, W Kern, RG Kazarians, GA Benton, EV Benton, ER Nelson, GA TI A comparison of mutations induced by accelerated iron particles versus those induced by low earth orbit space radiation in the FEM-3 gene of Caenorhabditis elegans SO MUTATION RESEARCH-FUNDAMENTAL AND MOLECULAR MECHANISMS OF MUTAGENESIS LA English DT Article DE C. elegans; accelerated particles; space radiation; heavy ion mutagenesis ID CHROMOSOMAL INSTABILITY; CELLS; APOPTOSIS AB The fem-3 gene of Caenorhabditis elegans was employed to determine the mutation frequency as well as the nature of mutations induced by low earth orbit space radiation ambient to Space Shuttle flight STS-76. Recovered mutations were compared to those induced by accelerated iron ions generated by the AGS synchrotron accelerator at Brookhaven National Laboratory. For logistical reasons, dauer larvae were prepared at TCU, transported to either Kennedy Space Center or Brookhaven National Laboratory, flown in space or irradiated, returned to TCU and screened for mutants. A total of 25 fem-3 mutants were recovered after the shuttle flight and yielded a mutation frequency of 2.1 x 10(-5). roughly 3.3-fold higher than the spontaneous rate of 6.3 x 10(-6). Four of the mutations were homozygous inviable, suggesting that they were large deletions encompassing fem-3 as well as neighboring, essential genes. Southern blot analyses revealed that one of the 25 contained a polymorphism in fem-3, further evidence that space radiation can induce deletions. While no polymorphisms were detected among the iron ion-induced mutations, three of the 15 mutants were homozygous inviable. which is in keeping with previous observations that high LET iron particles generate deficiencies. These data provide evidence, albeit indirect, that an important mutagenic component of ambient space radiation is high LET charged particles such as iron ions. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Texas Christian Univ, Dept Biol, Ft Worth, TX 76129 USA. CALTECH, Jet Prop Lab, Planetary Protect Technol Grp, Pasadena, CA 91109 USA. Univ San Francisco, Dept Phys, San Francisco, CA 94117 USA. Loma Linda Univ, Radiobiol Program, Loma Linda, CA 92354 USA. RP Hartman, PS (reprint author), Texas Christian Univ, Dept Biol, Ft Worth, TX 76129 USA. OI Hlavacek, Anthony/0000-0002-8281-1522 NR 26 TC 20 Z9 25 U1 0 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0027-5107 J9 MUTAT RES-FUND MOL M JI Mutat. Res.-Fundam. Mol. Mech. Mutagen. PD MAR 1 PY 2001 VL 474 IS 1-2 BP 47 EP 55 DI 10.1016/S0027-5107(00)00154-8 PG 9 WC Biotechnology & Applied Microbiology; Genetics & Heredity; Toxicology SC Biotechnology & Applied Microbiology; Genetics & Heredity; Toxicology GA 411HM UT WOS:000167492500005 PM 11239962 ER PT J AU Osman, MA Srivastava, D AF Osman, MA Srivastava, D TI Temperature dependence of the thermal conductivity of single-wall carbon nanotubes SO NANOTECHNOLOGY LA English DT Article ID DYNAMICS AB The thermal conductivity of several single-wall carbon nanotubes has been calculated over a temperature range of 100-500 K using molecular dynamics simulations with the Tersoff-Brenner potential for C-C interactions. In all cases, starting from similar values at 100 K, the thermal conductivities show a peaking behaviour before falling off at higher temperatures. The peak position shifts to higher temperatures for nanotubes with larger diameters and no significant dependence on the tube chirality is observed. It is shown that this phenomenon is due to the onset of Umklapp scattering, which shifts to higher temperatures for nanotubes with larger diameters. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Washington State Univ, Sch Elect Engn & Comp Sci, Pullman, WA 99164 USA. RP Osman, MA (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 18 TC 273 Z9 285 U1 5 U2 62 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0957-4484 EI 1361-6528 J9 NANOTECHNOLOGY JI Nanotechnology PD MAR PY 2001 VL 12 IS 1 BP 21 EP 24 DI 10.1088/0957-4484/12/1/305 PG 4 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied SC Science & Technology - Other Topics; Materials Science; Physics GA 420BB UT WOS:000167983100006 ER PT J AU Schenk, PM McKinnon, WB Gwynn, D Moore, JM AF Schenk, PM McKinnon, WB Gwynn, D Moore, JM TI Flooding of Ganymede's bright terrains by low-viscosity water-ice lavas SO NATURE LA English DT Article ID GALILEAN SATELLITES; GROOVED TERRAIN; THERMAL EVOLUTION; STEREO IMAGES; STRATIGRAPHY; TOPOGRAPHY; VOLCANISM AB Large regions of the jovian moon Ganymede have been resurfaced, but the means has been unclear(1,2). Suggestions have ranged from volcanic eruptions of liquid water(3-5) or solid ice(6) to tectonic deformation(7-9), but definitive high-resolution morphological evidence has been lacking. Here we report digital elevation models of parts of the surface of Ganymede, derived from stereo pairs combining data from the Voyager and Galileo spacecraft, which reveal bright, smooth terrains that lie at roughly constant elevations 100 to 1,000 metres below the surrounding rougher terrains. These topographic data, together with new images that show fine-scale embayment and burial of older features(10), indicate that the smooth terrains were formed by flooding of shallow structural troughs by low-viscosity water-ice lavas. The oldest and most deformed areas (the 'reticulate' terrains) in general have the highest relative elevations, whereas units of the most common resurfaced type-the grooved terrain-lie at elevations between those of the smooth and reticulate terrains. Bright terrain, which accounts for some two-thirds of the surface, probably results from a continuum of processes, including crustal rifting, shallow flooding and groove formation. Volcanism plays an integral role in these processes, and is consistent with partial melting of Ganymede's interior(11,12). C1 Lunar & Planetary Inst, Houston, TX 77058 USA. Washington Univ, Dept Earth & Planetary Sci, St Louis, MO 63130 USA. Washington Univ, McDonnell Ctr Space Sci, St Louis, MO 63130 USA. Univ Calif Los Angeles, Dept Geog, Los Angeles, CA 90095 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Schenk, PM (reprint author), Lunar & Planetary Inst, 3303 NASA Rd 1, Houston, TX 77058 USA. NR 23 TC 44 Z9 45 U1 0 U2 5 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD MAR 1 PY 2001 VL 410 IS 6824 BP 57 EP 60 DI 10.1038/35065027 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 406BD UT WOS:000167194300038 PM 11242037 ER PT J AU Le Roux, PD Das, H Esquenazi, S Kelly, PJ AF Le Roux, PD Das, H Esquenazi, S Kelly, PJ TI Robot-assisted microsurgery: A feasibility study in the rat SO NEUROSURGERY LA English DT Article DE dexterity enhancement; microsurgery; telerobotics ID SURGERY AB OBJECTIVE: Telerobotic surgery is a novel technology that can improve a surgeon's manual dexterity as well as the results achieved with microsurgical procedures. METHODS: A prototype Robot-Assisted MicroSurgery (RAMS) microdexterity enhancement system developed by the Jet Propulsion Laboratory and MicroDexterity Systems, Inc., was tested in 10 rats. Carotid arteriotomies were created and closed using either the RAMS system or conventional microsurgical techniques. The time required, the technical quality (vessel patency and suture line integrity), the error rate, and subjective difficulty were compared. RESULTS: All procedures were successfully completed using the RAMS system to manipulate the vessel but not to hold the needle or place the sutures. The precision, technical quality, and error rate of telerobotic surgery were similar to those of conventional techniques. However, the use of the RAMS system was associated with a twofold increase in the length of the procedure. CONCLUSION: Surgery using a microdexterity enhancement system, or RAMS prototype, is feasible. With further development, such as a stereotelevisualization and haptic feedback system, this system could be used for telerobotic surgery in neurosurgical practice. C1 NYU Med Ctr, Dept Neurosurg, New York, NY 10016 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. RP Univ Penn, Dept Neurosurg, 330 S 9th St,4th Floor, Philadelphia, PA 19107 USA. EM LEROUX@UPHS.upenn.edu NR 21 TC 50 Z9 50 U1 0 U2 5 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA TWO COMMERCE SQ, 2001 MARKET ST, PHILADELPHIA, PA 19103 USA SN 0148-396X J9 NEUROSURGERY JI Neurosurgery PD MAR PY 2001 VL 48 IS 3 BP 584 EP 589 DI 10.1097/00006123-200103000-00026 PG 6 WC Clinical Neurology; Surgery SC Neurosciences & Neurology; Surgery GA 408AH UT WOS:000167304000066 PM 11270549 ER PT J AU Davis, AB Marshak, A AF Davis, AB Marshak, A TI Multiple scattering in clouds: Insights from three-dimensional difusion/P-1 theory SO NUCLEAR SCIENCE AND ENGINEERING LA English DT Article ID STOCHASTIC RADIATIVE-TRANSFER; AVERAGED SOLAR FLUXES; DIFFUSION-COEFFICIENT; STRATOCUMULUS CLOUDS; INDEPENDENT PIXEL; ABSORPTION; APPROXIMATION; PARAMETERIZATION; SPECTROSCOPY; SKYLIGHT AB In the atmosphere, multiple scattering matters nowhere more than in clouds, and being a product of its turbulence, clouds are highly variable environments. This challenges three-dimensional (3D) radiative transfer theory in a way that easily swamps any available computational resources. Fortunately, the far simpler diffusion (or P-1) theory becomes more accurate as the scattering intensifies, and allows for some analytical progress as well as computational efficiency. After surveying current approaches to 3D solar cloud-radiation problems from the diffusion standpoint, a general 3D result in steady-state diffusive transport is derived relating the variability-induced change in domain-average flux (i.e., diffuse transmittance) to the one-point covariance of internal fluctuations in particle density and in radiative flux. These flux variations follow specific spatial patterns in deliberately hydrodynamical language: radiative channeling. The P-1 theory proves even more powerful when the photon diffusion process unfolds in time as well as space. For slab geometry, characteristic times and lengths that describe normal and transverse transport phenomena are derived. This phenomenology is used to (a) explain persistent features in satellite images of dense stratocumulus as radiative channeling, (b) set limits on current cloud remote-sensing techniques, and (c) propose new ones both active and passive. C1 Los Alamos Natl Lab, Space & Remote Sensing Sci Grp, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Climate & Radiat Branch, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Baltimore, MD USA. RP Los Alamos Natl Lab, Space & Remote Sensing Sci Grp, NIS-2, Los Alamos, NM 87545 USA. EM adavis@lanl.gov RI Marshak, Alexander/D-5671-2012 NR 83 TC 28 Z9 29 U1 0 U2 3 PU AMER NUCLEAR SOC PI LA GRANGE PK PA 555 N KENSINGTON AVE, LA GRANGE PK, IL 60526 USA SN 0029-5639 EI 1943-748X J9 NUCL SCI ENG JI Nucl. Sci. Eng. PD MAR PY 2001 VL 137 IS 3 BP 251 EP 280 PG 30 WC Nuclear Science & Technology SC Nuclear Science & Technology GA 405GX UT WOS:000167152600004 ER PT J AU Wilson, RV Demuren, AO Carpenter, M AF Wilson, RV Demuren, AO Carpenter, M TI Higher-order compact schemes for numerical simulation of incompressible flows, part II: Applications SO NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS LA English DT Article AB A higher-order-accurate numerical procedure, developed Sos solving incompressible Navier-Stokes equations for 2-D or 3-D fluid flow problems and presented in Part I, is validated. The procedure, which is based on low-storage Runge-Kutta schemes for temporal discretization and fourth- and sixth-order compact finite-difference schemes Sol spatial discretization, is shown to eliminate the odd-even decoupling problem on regular grids, provided that compact schemes me used to approximate the Laplacian of the pressure equation. Spatial and temporal accuracy ale confirmed formally through application to several pertinent benchmark problems. Stability in long-time integration is demonstrated by application to the Stuart's mixing-layer problem. C1 Old Dominion Univ, Dept Engn Mech, Norfolk, VA 23529 USA. NASA, Langley Res Ctr, Acoust & Flow Methods Branch, Hampton, VA 23665 USA. RP Demuren, AO (reprint author), Old Dominion Univ, Dept Engn Mech, Norfolk, VA 23529 USA. NR 13 TC 11 Z9 11 U1 0 U2 2 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 USA SN 1040-7790 J9 NUMER HEAT TR B-FUND JI Numer Heat Tranf. B-Fundam. PD MAR PY 2001 VL 39 IS 3 BP 231 EP 255 PG 25 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA 416XD UT WOS:000167804900002 ER PT J AU Ilchenko, VS Gorodetsky, ML Yao, XS Maleki, L AF Ilchenko, VS Gorodetsky, ML Yao, XS Maleki, L TI Microtorus: a high-finesse microcavity with whispering-gallery modes SO OPTICS LETTERS LA English DT Article ID Q MICROSPHERE CAVITY; RESONATOR; LASER AB We demonstrate a 165-mum oblate spheroidal microcavity with a free spectral range of 383.7 GHz (3.06 nm), a resonance bandwidth of 23 MHz (quality factor Q approximate to 10(7)) at 1550 nm,and finesse F greater than or equal to 10(4). The highly oblate spheroidal dielectric microcavity combines a very high Q factor, typical of microspheres, with a vastly reduced number of excited whispering-gallery modes (by 2 orders of magnitude). The very large free spectral range in this novel microcavity-a few hundred gigahertz instead of a few gigahertz as in typical microspheres-is desirable for applications in spectral analysis, narrow-linewidth optical and rf oscillators, and cavity QED. (C) 2001 Optical Society of America. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Moscow MV Lomonosov State Univ, Dept Phys, Moscow 119899, Russia. RP Ilchenko, VS (reprint author), CALTECH, Jet Prop Lab, MS 298-100,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Gorodetsky, Michael/C-5938-2008 OI Gorodetsky, Michael/0000-0002-5159-2742 NR 14 TC 72 Z9 72 U1 2 U2 21 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD MAR 1 PY 2001 VL 26 IS 5 BP 256 EP 258 DI 10.1364/OL.26.000256 PG 3 WC Optics SC Optics GA 405WK UT WOS:000167183400002 PM 18040293 ER PT J AU Mehrotra, P Zima, H AF Mehrotra, P Zima, H TI High performance Fortran for aerospace applications SO PARALLEL COMPUTING LA English DT Article DE distributed memory multiprocessing; high-level language; distribution directives ID EXECUTION; LOOPS AB This paper focuses on the use of high-performance Fortran (HPF) for important classes of algorithms employed in aerospace applications. HPF is a set of Fortran extensions designed to provide users with a high-level interface for programming data parallel scientific applications, while delegating to the compiler/runtime system the task of generating explicitly parallel message-passing programs. We begin by providing a short overview of the HPF language. This is followed by a detailed discussion of the efficient use of HPF for applications involving multiple structured grids such as multiblock and adaptive mesh refinement (AMR) codes as well as unstructured grid codes. We focus on the data structures and computational structures used in these codes and on the high-level strategies that can be expressed in HPF to optimally exploit the parallelism in these algorithms. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. Univ Vienna, Inst Software Sci, A-1090 Vienna, Austria. RP Mehrotra, P (reprint author), NASA, Langley Res Ctr, ICASE, MS 132C, Hampton, VA 23681 USA. EM pm@icase.edu; zima@par.univie.ac.at NR 23 TC 1 Z9 1 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 MAR PY 2001 VL 27 IS 4 BP 477 EP 501 DI 10.1016/S0167-8191(00)00073-9 PG 25 WC Computer Science, Theory & Methods SC Computer Science GA 418EP UT WOS:000167878200008 ER PT J AU Taft, JR AF Taft, JR TI Achieving 60 GFLOP/s on the production CFD code OVERFLOW-MLP SO PARALLEL COMPUTING LA English DT Article DE overflow; overflow-MLP; MLP; multi-level parallelism AB NASA Ames has developed a new methodology for achieving very high levels of parallel efficiency on the new NUMA based shared memory symmetric Multi-Processing (SMP) computing systems available today. This methodology is simple, general, and widely applicable to production CFD codes in use at NASA and elsewhere. The new methodology is formally called shared memory Multi-Level Parallelism (MLP), and is based on shared memory access to global data while invoking two levels of parallelism for scaling efficiency. During the past year, this technique has been refined and improved and inserted into the OVERFLOW production CFD code. Executions of the new code on an SGI Origin R12K system with 512 CPUs have demonstrated over 60 GFLOP/s of sustained performance for customer driven real problems. A detailed discussion of the MLP technique, OVERFLOW-MLP code optimizations, and performance results are presented. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Taft, JR (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 4 TC 11 Z9 11 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 MAR PY 2001 VL 27 IS 4 BP 521 EP 536 DI 10.1016/S0167-8191(00)00072-7 PG 16 WC Computer Science, Theory & Methods SC Computer Science GA 418EP UT WOS:000167878200010 ER PT J AU Strekalov, VN Strekalov, DV AF Strekalov, VN Strekalov, DV TI Photodesorption of charge impurities from a transparent crystal surface SO PHYSICAL REVIEW A LA English DT Article ID DESORPTION; MODEL AB Photodesorption of impurity ions is studied iri the framework of a truncated harmonic oscillator model and is considered as a direct photon absorption process without substrate heating. The desorption rate is found by methods of quantum statistics, using the System's evolution operator. The desorption rates estimates appear realistic. Our results predict a series of new physical effects in desorption processes. C1 Moscow State Univ Technol STANKIN, Dept Phys, Moscow 101472, Russia. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Strekalov, VN (reprint author), Moscow State Univ Technol STANKIN, Dept Phys, 3A Vadkovsky, Moscow 101472, Russia. EM stvn@sec.ru NR 14 TC 1 Z9 1 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 MAR PY 2001 VL 63 IS 3 AR 032901 PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA 408HP UT WOS:000167321000076 ER PT J AU Gross, RS AF Gross, RS TI A combined length-of-day series spanning 1832-1997: LUNAR97 SO PHYSICS OF THE EARTH AND PLANETARY INTERIORS LA English DT Article DE Earth rotation; universal time; length-of-day; lunar occultation ID EARTH ORIENTATION PARAMETERS; HIPPARCOS REFERENCE FRAME; UNIVERSAL TIME; ROTATION; FLUCTUATIONS; MOMENTUM AB Universal time (UT) measurements taken by the techniques of lunar occultation, optical astrometry, lunar laser ranging, and very long baseline interferometry have been combined using a Kalman filter to produce a smoothed length-of-day (LOD) series, LUNAR97, spanning 1832.5-1997.5 at yearly intervals. Decadal LOD variations having amplitudes as large as a few milliseconds (ms) are clearly evident in this newly determined series as they have been in previously determined series. Comparing the LUNAR97 LOD series with other available series shows differences that are generally less than the uncertainty in the determination of the LUNAR97 LOD values, which is about 0.6 ms during the early 19th century, improving by more than an order of magnitude to about 0.03 ms during the late 20th century. Decadal LOD variations are, therefore, a robust feature of the lunar occultation, optical astrometric, and space-geodetic measurements of the Earth's rotation that have been taken since 1832. C1 CALTECH, Jet Prop Lab, Space Geodet Sci & Applicat Grp, Pasadena, CA 91109 USA. RP Gross, RS (reprint author), CALTECH, Jet Prop Lab, Space Geodet Sci & Applicat Grp, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 30 TC 20 Z9 21 U1 1 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0031-9201 J9 PHYS EARTH PLANET IN JI Phys. Earth Planet. Inter. PD MAR PY 2001 VL 123 IS 1 BP 65 EP 76 DI 10.1016/S0031-9201(00)00217-X PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 411BR UT WOS:000167478700005 ER PT J AU Roth, I Ramaty, R AF Roth, I Ramaty, R TI High-latitude radiation and resonant enhancements of the Jovian synchrotron emissions SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Annual Conference on Magnetospheres of Outer Planets (MOP) CY AUG 09-14, 1999 CL PARIS, FRANCE ID ENERGETIC ELECTRONS; DIFFUSION-MODELS; WHISTLERS; JUPITER; DISPERSION; VOYAGER-1; DENSITY; TORUS; RAY AB A model describing (1) short time scale increases in Jovian synchrotron radiation and (2) emissions from high Jovian latitudes is presented. In the present model resonant interaction between oblique whistler waves and relativistic electrons diffuses the energy and the pitch angle of electrons which bounce along the Jovian magnetic field. The resonant interaction violates the first two adiabatic invariants and the energy diffusion results in hardening of the electron spectrum and in intensification of the synchrotron radiation. This model complements the radial diffusion process which (a) Violates the third adiabatic invariant of a seed population via interaction with low-frequency magnetospheric oscillations and (b) increases the flux of energetic electrons at low L-shells over long time scales by conserving the first adiabatic invariant. The high-latitude emissions indicate also acceleration of bouncing electrons and radiation in the region of the strongest magnetic field. The seed particles and whistler waves determine the form of the electron distribution tail. This tail enhances the high-latitude synchrotron radiation observed at Earth. The resulting emissivities of the nonthermal radio waves in the ordinary/extraordinary modes of propagation, the polarization and the intensity spectrum observed at Earth due to these high-energy populations are calculated (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Roth, I (reprint author), Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. NR 27 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAR-APR PY 2001 VL 49 IS 3-4 SI SI BP 313 EP 318 DI 10.1016/S0032-0633(00)00152-5 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 415GL UT WOS:000167712600009 ER PT J AU Kurth, WS Gurnett, DA Persoon, AM Roux, A Bolton, SJ Alexander, CJ AF Kurth, WS Gurnett, DA Persoon, AM Roux, A Bolton, SJ Alexander, CJ TI The plasma wave environment of Europa SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Annual Conference on Magnetospheres of Outer Planets (MOP) CY AUG 09-14, 1999 CL PARIS, FRANCE ID SOLITARY WAVES; ELECTROSTATIC-WAVES; DOUBLE-LAYERS; MAGNETOSPHERE; MAGNETOTAIL; REGION; ION AB The Galileo spacecraft has executed nine close flybys of Jupiter's moon Europa for which plasma wave observations were obtained. This paper presents an analysis of the observations from these flybys laking into consideration the Variable geometry of the trajectories in an attempt to characterize the general plasma-wave environment associated with the interaction of the Jovian magnetosphere with the moon. A wide variety of plasma-wave phenomena are found to be associated with this interaction. While there are apparently temporal variations which complicate the analysis, a crude model of the distribution of these phenomena around Europa is derived. Primarily on the upstream side of Europa, and working inward to the moon, electron-cyclotron harmonics are first observed, followed by a region within about two Europa radii of the moon with whistler-mode hiss or chorus, and culminating in a region closest to the moon where a band at the upper hybrid resonance frequency is sometimes enhanced over its ambient intensity. The wake region is approximately two Europa radii across and comprises a broadband, highly variable, and bursty electrostatic phenomenon. Upon closer inspection, these bursty emissions appear as solitary structures similar to those in Earth s auoral zone and plasma sheet boundary layer. In addition to the survey of wave phenomena in the vicinity of Europa, we provide density profiles derived primarily from the upper hybrid resonance frequency which is readily apparent throughout most of each of the flybys. Finally, we suggest that the whistler mode, electron cyclotron harmonic, and upper hybrid resonance emissions are driven by some combination of factors including variations in the magnetic field near Europa and the loss and production of plasma at Europa as a result of the interaction of the Jovian magnetosphere with the moon. By analogy with studies of the ion and electron heres and broadband electrostatic noise at Earth and Jupiter, we argue that the electrostatic solitary structures in the wake are associated with currents and beams coupling Europa to Jupiter's ionosphere. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. UVSQ, CETP, Velizy, France. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kurth, WS (reprint author), Univ Iowa, Dept Phys & Astron, 613 Van Allen Hall, Iowa City, IA 52242 USA. OI Kurth, William/0000-0002-5471-6202 NR 29 TC 24 Z9 24 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAR-APR PY 2001 VL 49 IS 3-4 SI SI BP 345 EP 363 DI 10.1016/S0032-0633(00)00156-2 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 415GL UT WOS:000167712600013 ER PT J AU Barrow, CH Lecacheux, A MacDowall, RJ Kaiser, ML AF Barrow, CH Lecacheux, A MacDowall, RJ Kaiser, ML TI The Jovian HOM and bKOM radio emissions observed by Wind/WAVES and by Ulysses/URAP SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Annual Conference on Magnetospheres of Outer Planets (MOP) CY AUG 09-14, 1999 CL PARIS, FRANCE ID JUPITER; POLARIZATION; ENCOUNTER; VOYAGER; PLANETS AB During 1995 and into 1996, both the Jovian hectometric radio emission (HOM) and the Jovian broadband radio emission (bKOM) were received occasionally by the Radio and Plasma Wave Investigation (WAVES) on board the Wind spacecraft and by the Unified Radio and Plasma Experiment (URAP) on board the Ulysses spacecraft. Ulysses was then at distances of 5 AU or more from Jupiter and travelling from south to north of the ecliptic plane. At this distance from the planet, the events are generally weak and much care is needed to distinguish the HOM from weak solar type III emission and, in the Wind/WAVES observations, the bKOM from terrestrial auroral kilometric radiation (AKR). Characteristics of the emission, duration, frequency extent, structure and polarization give new information on the beaming and source location of the HOM and the bKOM. For the period studied, it was found that the bKOM events were observed by Ulysses when the spacecraft was at higher jovicentric latitudes, (D-Uly, greater than or equal to 15 degrees) while HOM events were recorded when the spacecraft was at lower jovicentric latitudes, -12 degrees less than or equal toD(Uly) less than or equal to 14 degrees. Polarization measurements suggest that, due to beaming, LH polarized radiation from the southern Jovian hemisphere HOM source is beamed towards Ulysses at jovicentric latitudes to the north of some value between -11.7 and -5.3 degrees. Conversely, RH polarized radiation from the northern hemisphere HOM source is beamed away from Ulysses at jovicentric latitudes to the north of some value between -11.7 and -5.3 degrees. For the events studied, if a two-dimensional tilted dipole model is assumed, the emission cone half-angle appears to be about 44 degrees for 940 kHz HOM emission from a source on L-shell about 10. There is no unique value for beta that does not involve assumed values of L and f(c) (Barrow and Lecacheux, Astron. Astrophys. 301 (1995) 903.) (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Max Planck Inst Aeron, D-37191 Katlenburg Lindau, Germany. Observ Paris, ARPEGES, F-92195 Meudon, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Barrow, CH (reprint author), Max Planck Inst Aeron, Max Planck Str 2, D-37191 Katlenburg Lindau, Germany. RI MacDowall, Robert/D-2773-2012 NR 23 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAR-APR PY 2001 VL 49 IS 3-4 SI SI BP 377 EP 384 DI 10.1016/S0032-0633(00)00158-6 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 415GL UT WOS:000167712600015 ER PT J AU Prange, R Chagnon, G Kivelson, MG Livengood, TA Kurth, W AF Prange, R Chagnon, G Kivelson, MG Livengood, TA Kurth, W TI Temporal monitoring of Jupiter's auroral activity with IUE during the Galileo mission. Implications for magnetospheric processes SO PLANETARY AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Annual Conference on Magnetospheres of Outer Planets (MOP) CY AUG 09-14, 1999 CL PARIS, FRANCE ID SOLAR-WIND CONTROL; JOVIAN MAGNETOTAIL; ULTRAVIOLET AURORA; RADIO-EMISSION; GIANT PLANETS; LYMAN-ALPHA; PRECIPITATION; SECTOR; FIELD; BANDS AB In this study, we analyze FUV auroral spectra of Jupiter acquired on a quasi-continuous basis between August 17 and September 25, 1996 as part of the last IUE Key Project. This campaign was coordinated with Galileo measurements. We show that it is possible to define an "auroral activity index" which quantifies the variability of the flux radiated in the H-2 bands (1560-1620 a). The activity indices in both hemispheres are generally similar and indicate a strong interhemispheric conjugacy, suggestive of particle precipitation on closed field lines. We identify variability on three different scales: small Variations of 10-20% are observed on short time scales (Na few hours), Variations by a factor of 2-4 occur on scales of 5-10 days, and a long-term trend is observed on a scale which exceeds the 6 weeks of observations. The energy output in this spectral range is a direct measurement of the energy losses of the magnetosphere along auroral magnetic field lines. We establish here that its intermediate time-scale variations, the best documented ones in this study, are amazingly well correlated with the state (quiet or disturbed) of the magnetic field measured by the magnetometer on board Galileo, although distances from similar to 15 to similar to 115R(J) and all local times were sampled during that time. This indicates temporal, rather than spatial, variations of the magnetic field, and suggests that some dynamical process, yet to be identified, affects the magnetosphere as a whole and triggers recurrent energy releases along auroral field lines. The recurrence time derived from this study is larger than the 3-day periodicity previously assigned to variabilities in the magnetotail on the basis of Galileo measurements during other time periods. A crude preliminary comparison also indicates correlations with the intensity of the auroral kilometer radio waves and anticorrelations with the local plasma density, both derived from the Galileo PWS experiment. Comparison with other particle and field instruments is underway. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Paris 11, Inst Astrophys Spatiale, CNRS, F-91405 Orsay, France. Inst Astrophys, F-75014 Paris, France. Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90095 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Univ Maryland, Dept Astron, College Pk, MD 21042 USA. RP Prange, R (reprint author), Univ Paris 11, Inst Astrophys Spatiale, CNRS, Batiment 121, F-91405 Orsay, France. RI Livengood, Timothy/C-8512-2012; Kivelson, Margaret/I-9019-2012; OI Kivelson, Margaret/0000-0003-3859-8581; Kurth, William/0000-0002-5471-6202 NR 31 TC 18 Z9 18 U1 2 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAR-APR PY 2001 VL 49 IS 3-4 SI SI BP 405 EP 415 DI 10.1016/S0032-0633(00)00161-6 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 415GL UT WOS:000167712600018 ER PT J AU Condie, KC Marais, DJD Abbott, D AF Condie, KC Marais, DJD Abbott, D TI Precambrian superplumes and supercontinents: a record in black shales, carbon isotopes, and paleoclimates? SO PRECAMBRIAN RESEARCH LA English DT Review DE superplume; black shale; carbon isotopes; paleoclimates; carbon cycle ID PROTEROZOIC SEDIMENTARY-ROCKS; BANDED IRON-FORMATION; CENTRAL IBERIAN ZONE; SOUTH-AFRICA; WESTERN-AUSTRALIA; NORTHERN AUSTRALIA; ARCHEAN SHALES; DEPOSITIONAL ENVIRONMENT; VELKERRI FORMATION; CONTINENTAL-CRUST AB Prominent maxima in black shale abundance and in black shale/total shale ratio occur at 2.0-1.7 Ga, with less prominent peaks in the Late Neoproterozoic (800-600 Ma) and in the Late Archean (2.7-2.5 Ga). Peaks in chemical index of alteration (CIA) of shales at the same times suggest corresponding warm paleoclimates. The peaks in CIA and black shale abundance are correlated in time at a 94% confidence level. The black shale and CIA peaks may reflect the combined effects of mantle superplume events and supercontinent formation at 2.7 and 1.9 Ga. Mantle superplume events may have introduced large amounts of CO2 into the atmosphere-ocean system, increasing depositional rates of carbon and increasing global warming. Increased black shale deposition may reflect some combination of: (1) increased oceanic hydrothermal fluxes (introducing nutrients); (2) anoxia on continental shelves; and (3) disrupted ocean currents. The apparent absence of carbon isotope anomalies at these times reflects an increase in the deposition and burial rate of both reduced and oxidized carbon. Peaks in black shale abundance at similar to 2.1 Ga and 800-600 Ma correlate with peaks in delta C-13 in marine carbonates, increases in atmospheric oxygen, and with high CIA values in shales. These are all consistent with higher rates of organic carbon burial in black shales at these times. These peaks may record the breakup of supercontinents at 2.2-2.0 Ga and again at 800-600 Ma, which resulted in increased numbers of partially closed marine basins, disruption of ocean currents, and increased hydrothermal vents at ocean ridges, all of which led to widespread anoxia. (C) 2001 Elsevier Science B.V. All rights reserved. C1 New Mexico Inst Min & Technol, Dept Earth & Environm Sci, Socorro, NM 87801 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Lamont Doherty Earth Observ, Palisades, NY 10964 USA. RP New Mexico Inst Min & Technol, Dept Earth & Environm Sci, Socorro, NM 87801 USA. EM kcondie@nmt.edu NR 102 TC 127 Z9 144 U1 2 U2 33 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-9268 EI 1872-7433 J9 PRECAMBRIAN RES JI Precambrian Res. PD MAR 1 PY 2001 VL 106 IS 3-4 BP 239 EP 260 DI 10.1016/S0301-9268(00)00097-8 PG 22 WC Geosciences, Multidisciplinary SC Geology GA 408EW UT WOS:000167314400003 ER PT J AU Southward, RE Stoakley, DM AF Southward, RE Stoakley, DM TI Reflective and electrically conductive surface silvered polyimide films and coatings prepared via unusual single-stage self-metallization techniques SO PROGRESS IN ORGANIC COATINGS LA English DT Review DE chemical vapor deposition; electrically conductive surface; polyimide films; self-metallization; silver(I) precursors ID CHEMICAL-VAPOR-DEPOSITION; IN-SITU REDUCTION; PHOTOEMISSION; CHEMISTRY; ADHESION; PRECURSORS; PALLADIUM; COMPLEXES; COPPER; OPTICS AB Highly reflective and/or surface conductive flexible polyimide films can be prepared by the incorporation of positive valent silver compounds into solutions of poly(amic acid)s formed from a variety of dianhydrides and diamines. Thermal curing of selected silver(I)-containing poly(amic acid)s leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction and surface aggregation of the metal yielding a reflective and/or conductive silver surface similar to that of the native metal. However, not all silver(I) precursors are effective surface metallization agents and not all poly(amic acid)s metallize with equal facility. Ligand/anion and polyimide structural effects on film metallization efficacy and on physical properties on metallized films are reviewed. Published by Elsevier Science B.V. C1 NASA, Langley Res Ctr, Hampton, VA 23581 USA. RP Southward, RE (reprint author), NASA, Langley Res Ctr, Hampton, VA 23581 USA. NR 72 TC 41 Z9 45 U1 6 U2 30 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0300-9440 J9 PROG ORG COAT JI Prog. Org. Coat. PD MAR PY 2001 VL 41 IS 1-3 BP 99 EP 119 DI 10.1016/S0300-9440(00)00156-9 PG 21 WC Chemistry, Applied; Materials Science, Coatings & Films SC Chemistry; Materials Science GA 427HV UT WOS:000168399500004 ER PT J AU Ruthruff, E Pashler, HE Klaassen, A AF Ruthruff, E Pashler, HE Klaassen, A TI Processing bottlenecks in dual-task performance: Structural limitation or strategic postponement? SO PSYCHONOMIC BULLETIN & REVIEW LA English DT Article ID OVERLAPPING TASKS; INTERFERENCE; ATTENTION AB Recent evidence indicates that a central bottleneck causes much of the slowing that occurs when two tasks are performed at the same time. This bottleneck might reflect a structural limitation inherent in the cognitive architecture. Alternatively, the bottleneck might reflect strategic (i.e., voluntary) postponement, induced by instructions to emphasize one task over the other. To distinguish structural limitations from strategic postponement, we examine a new paradigm in which subjects are told to place equal emphasis on both tasks and to emit both responses at about the same time. An experiment using this paradigm demonstrated patterns of interference that cannot easily be attributed to strategic postponement, preparation effects, or conflicts in response production. The data conform closely to the predictions of structural central bottleneck models. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif San Diego, San Diego, CA 92103 USA. RP Ruthruff, E (reprint author), NASA, Ames Res Ctr, MS 262-4, Moffett Field, CA 94035 USA. FU NIMH NIH HHS [1F31-MH10922, 1-R29-MH45584] NR 26 TC 94 Z9 95 U1 0 U2 4 PU PSYCHONOMIC SOC INC PI AUSTIN PA 1710 FORTVIEW RD, AUSTIN, TX 78704 USA SN 1069-9384 J9 PSYCHON B REV JI Psychon. Bull. Rev. PD MAR PY 2001 VL 8 IS 1 BP 73 EP 80 DI 10.3758/BF03196141 PG 8 WC Psychology, Mathematical; Psychology, Experimental SC Psychology GA 426LZ UT WOS:000168351800006 PM 11340869 ER PT J AU Guffey, CJ Helms, MM AF Guffey, CJ Helms, MM TI Effective employee discipline: A case of the internal revenue service SO PUBLIC PERSONNEL MANAGEMENT LA English DT Article AB The role of employee discipline from a management, employee, and union perspective is examined using the Internal Revenue Service as a case study example. The concept of discipline is defined and contrasted with punishment. Also, two discipline models - progressive discipline and positive discipline - are compared and contrasted. A hybrid discipline model used at the internal Revenue Service is discussed; the roles and responsibilities of management, the union, and the employee in the discipline process are included also. In particular, the roles of IRS managers and the National Treasury Employees Union (NTEU) are outlined. Results from the recently released IRS/NTEU National Equal Employment Opportunity Task Force Report are highlighted. Several discipline pitfalls are outlined including: cultural diversity issues, tolerance of poor performers, and lack of managerial training. To make the disciplinary process fairer and less stressful for managers end all employees, recommendations from the IRS/NTEU report are presented. C1 George C Marshall Space Flight Ctr, Madison, AL 35758 USA. Dalton State Coll, Dalton, GA 30720 USA. RP Guffey, CJ (reprint author), George C Marshall Space Flight Ctr, 3501 Royal Dr,Suite 3501, Madison, AL 35758 USA. NR 20 TC 3 Z9 3 U1 2 U2 4 PU INT PERSONNEL MANAGEMENT ASSN PI ALEXANDRIA PA 1617 DUKE ST, ALEXANDRIA, VA 22314 USA SN 0091-0260 J9 PUBLIC PERS MANAGE JI Public Personnel Manage. PD SPR PY 2001 VL 30 IS 1 BP 111 EP 127 PG 17 WC Industrial Relations & Labor; Public Administration SC Business & Economics; Public Administration GA 426MX UT WOS:000168353900010 ER PT J AU Shi, F AF Shi, F TI Sodium laser guide star experiment with a sum-frequency laser for adaptive optics SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID MESOSPHERIC SODIUM; TELESCOPE; SYSTEMS; PERFORMANCE; EXCITATION; BEACONS; CHAOS AB A sodium laser guide star (LGS) experiment for astronomical adaptive optics (AO) using a diode-laser pumped sum-frequency laser is described. Results of the LGS experiment from 1997 October to 1998 February are presented and discussed. An LGS as bright as 9.5 mag and as small as a natural star has been formed with about 1.1 W of laser power incident at the mesosphere. The experimental data indicate that the optical pumping effects have enhanced the LGS brightness by about 40%-50%. The laser has been shown to be efficient and robust and can already be used as a facility instrument on the astronomical AO system. The predicted wave-front sensor measurement errors for typical AO systems have been calculated from the observed LGS flux and spot profile. Wave-front errors of 83 nm with the current Chicago Adaptive Optics System (ChAOS) at the winter (maximum) sodium abundance level and 96 nm with the improved ChAOS and laser system at the summer (minimum) sodium abundance level are predicted. C1 Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Shi, F (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 306-438, Pasadena, CA 91109 USA. EM Fang.Shi@jpl.nasa.gov NR 24 TC 6 Z9 7 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD MAR PY 2001 VL 113 IS 781 BP 366 EP 378 DI 10.1086/319327 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 409XC UT WOS:000167410100010 ER PT J AU Bilitza, D AF Bilitza, D TI International Reference Ionosphere 2000 SO RADIO SCIENCE LA English DT Article; Proceedings Paper CT Ionospheric Effect Symposium (IES 99) CY MAY 04-06, 1999 CL ALEXANDRIA, VIRGINIA SP Air Force Off Sci Res, Fed Aviat Adm, Off Naval Res, Air Force Res Lab, Air Force Space & Missile Syst Ctr, Fed Communicat Commiss, Natl Ocean & Atmospher Adm, Naval Res Lab, Univ Massachusetts Lowell, NW Res Associates, USA, Communicat Electr Command, Innovat Solut Int Inc ID ELECTRON-DENSITY PROFILES; INTENSE SOLAR-CYCLE; ION COMPOSITION; CRITICAL FREQUENCY; EMPIRICAL-MODEL; LOW LATITUDES; IRI; REGION; LAYER; PREDICTIONS AB The International Reference Ionosphere (IRI) is the international standard for the specification of ionospheric densities and temperatures. It was developed and is being improved-updated by a joint working group of the International Union of Radio Science (URSI) and the Committee on Space Research (COSPAR). A new version of IRI is scheduled for release in the year 2000. This paper describes the most important changes compared to the current version of IRI: (1) an improved representation of the electron density in the region from the F peak down to the E peak including a better description of the F, layer occurrence statistics and a more realistic description of the low-latitude bottomside thickness, (2) inclusion of a model for storm-time conditions, (3) inclusion of an ion drift model, (4) two new options for the electron density in the D region, and (5) an improved model for the topside electron temperatures. The outcome of the most recent IRI Workshops (Kuhlungsborn, 1997, and Nagoya, 1998) will be reviewed, and the status of several ongoing task force activities (e.g., efforts to improve the representation of electron and ion densities in the topside ionosphere and the inclusion of a plasmaspheric extension) will be discussed. A few typical IRI applications will be highlighted in section 6. C1 Raytheon Tech Serv Co, Informat Technol Serv, Lanham, MD USA. Raytheon Tech Serv Co, Sci Serv, Lanham, MD USA. RP Bilitza, D (reprint author), NASA, Goddard Space Flight Ctr, Code 632, Greenbelt, MD 20771 USA. NR 109 TC 808 Z9 848 U1 5 U2 33 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD MAR-APR PY 2001 VL 36 IS 2 BP 261 EP 275 DI 10.1029/2000RS002432 PG 15 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 415VR UT WOS:000167744700009 ER PT J AU Benson, RF Grebowsky, JM AF Benson, RF Grebowsky, JM TI Extremely low ionospheric peak altitudes in the polar hole region SO RADIO SCIENCE LA English DT Article; Proceedings Paper CT Ionospheric Effect Symposium (IES 99) CY MAY 04-06, 1999 CL ALEXANDRIA, VIRGINIA SP Air Force Off Sci Res, Fed Aviat Adm, Off Naval Res, Air Force Res Lab, Air Force Space & Missile Syst Ctr, Fed Communicat Commiss, Natl Ocean & Atmospher Adm, Naval Res Lab, Univ Massachusetts Lowell, NW Res Associates, USA, Communicat Electr Command, Innovat Solut Int Inc ID WINTER F-REGION; LOW MAGNETIC ACTIVITY; SOLAR MINIMUM; DENSITY AB Vertical electron density N-e profiles, deduced from newly available ISIS 2 digital ionospheric topside sounder data, are used to investigate the altitude structure of localized ionization depletions within the winter, nighttime polar cap ionosphere during solar minimum. The region investigated, called the polar hole-auroral cavity region, is located just after midnight magnetic local time near the poleward side of the auroral oval. Earlier investigations had at times found very low N-e values in this region (down to 200 cm(-3) near 300 km). In the present study, latitudinal N-e depletions were found, but such low N-e values (approximate to 100 cm(-3)) were only found near the ISIS 2 altitude of 1400 km. The peak ionospheric concentration below ISIS 2 remained fairly constant (similar to 10(5) cm(-3)) across the N-e-depleted region, but the altitude of the peak dropped dramatically to the vicinity of 100 km. The observations, in combination with other data, indicate that the absence of an F layer peak may be a frequent occurrence at high latitudes and stress the importance of a knowledge of the vertical N-e distribution in high-latitude investigations of horizontal N-e structures. C1 NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Benson, RF (reprint author), NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Mail Code 692, Greenbelt, MD 20771 USA. RI Grebowsky, Joseph/I-7185-2013 NR 17 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD MAR-APR PY 2001 VL 36 IS 2 BP 277 EP 285 DI 10.1029/1999RS002401 PG 9 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 415VR UT WOS:000167744700010 ER PT J AU Harris, IL Mannucci, AJ Iijima, BA Lindqwister, UJ Muna, D Pi, X Wilson, BD AF Harris, IL Mannucci, AJ Iijima, BA Lindqwister, UJ Muna, D Pi, X Wilson, BD TI Ionospheric specification algorithms for precise GPS-based aircraft navigation SO RADIO SCIENCE LA English DT Article; Proceedings Paper CT Ionospheric Effect Symposium (IES 99) CY MAY 04-06, 1999 CL ALEXANDRIA, VIRGINIA SP Air Force Off Sci Res, Fed Aviat Adm, Off Naval Res, Air Force Res Lab, Air Force Space & Missile Syst Ctr, Fed Communicat Commiss, Natl Ocean & Atmospher Adm, Naval Res Lab, Univ Massachusetts Lowell, NW Res Associates, USA, Communicat Electr Command, Innovat Solut Int Inc AB The Federal Aviation Administration (FAA) is implementing an aircraft navigation scheme for the United States using the Global Positioning System (GPS) L-1 signal (1575.42 MHz). To achieve position accuracies of a few meters, sufficient to allow precision airfield approaches, it will be necessary to broadcast corrections to the direct GPS signal. A significant component of these corrections is the delay in the GPS signal introduced by its propagation through the ionosphere. Ionospheric delay corrections will be derived using a ground network of at least 24 dual-frequency GPS receivers distributed across the continental United States. This network is part of the FAA's wide area augmentation system (WAAS) and will provide real-time total electron content (TEC) measurements. We present a technique for converting these TECs into gridded vertical delay corrections at the GPS L-1 frequency, which will be broadcast to users every 5 min via geosynchronous satellite. Users will convert these delays to slant corrections for their own particular lines of sight to GPS satellites. To preserve user safety, estimates of the error in the user delay corrections will also be broadcast. However, the error algorithm must not resort to excessive safety margins as this reduces the expected accuracy, and thus utility, of the navigation system. Here we describe an error algorithm and its dependence on various factors, such as user location with respect to the WAAS ground network and ionospheric conditions. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Harris, IL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,M-S 138-212, Pasadena, CA 91109 USA. RI Mannucci, Anthony/A-1349-2007 OI Mannucci, Anthony/0000-0003-2391-8490 NR 15 TC 4 Z9 4 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD MAR-APR PY 2001 VL 36 IS 2 BP 287 EP 298 DI 10.1029/1999RS002428 PG 12 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 415VR UT WOS:000167744700011 ER PT J AU Makela, JJ Kelley, MC Sojka, JJ Pi, XQ Mannucci, AJ AF Makela, JJ Kelley, MC Sojka, JJ Pi, XQ Mannucci, AJ TI GPS normalization and preliminary modeling results of total electron content during a midlatitude space weather event SO RADIO SCIENCE LA English DT Article; Proceedings Paper CT Ionospheric Effect Symposium (IES 99) CY MAY 04-06, 1999 CL ALEXANDRIA, VIRGINIA SP Air Force Off Sci Res, Fed Aviat Adm, Off Naval Res, Air Force Res Lab, Air Force Space & Missile Syst Ctr, Fed Communicat Commiss, Natl Ocean & Atmospher Adm, Naval Res Lab, Univ Massachusetts Lowell, NW Res Associates, USA, Communicat Electr Command, Innovat Solut Int Inc ID IONOSPHERIC MAPS; SATELLITE; NETWORK; BIASES; TOPEX; RADAR AB On November 22-23, 1997, a geomagnetic storm occurred during a period of excellent viewing conditions over the Arecibo Observatory in Puerto Rico. Here we explore the total electron content (TEC) registered by Global Positioning System (GPS) receivers located close to the Cornell All-Sky Imager (CASI) at the Arecibo Observatory. The storm began with the equatorward surge of a very high (100% increase) TEC enhancement stretching for many hours of local time on the dayside. At dusk the TEC over the Caribbean remained elevated with levels equal to the noontime monthly averages. During the event the TEC was highly structured and clearly correlated with high and low airglow emission levels. In one fortuitous instance a common ionospheric penetration point (15 km apart), shared by two GPS satellites viewed from two receiving stations, registered an 8 TEC unit difference during the active period. We show that a GPS station can be calibrated using the pseudorange method and a reliable data-driven technique during quiet conditions and still have absolute TEC capability within 2 TEC units (RMS) 5 days later. We compare the observations to a climatological model which, although reasonable for quiet times, is very poor during the storm period. We also present an independent evaluation of the GPS TEC. This study is an initial step toward quality control of this database, needed before it is used in an assimilation model. C1 Cornell Univ, Sch Elect & Comp Engn, Ithaca, NY 14853 USA. Space Environm Corp, Logan, UT 84321 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Makela, JJ (reprint author), Cornell Univ, Sch Elect & Comp Engn, 318 Rhodes Hall, Ithaca, NY 14853 USA. RI Mannucci, Anthony/A-1349-2007 OI Mannucci, Anthony/0000-0003-2391-8490 NR 16 TC 17 Z9 17 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD MAR-APR PY 2001 VL 36 IS 2 BP 351 EP 361 DI 10.1029/1999RS002427 PG 11 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA 415VR UT WOS:000167744700017 ER PT J AU Bell, D Menges, C Ahmad, W van Zyl, JJ AF Bell, D Menges, C Ahmad, W van Zyl, JJ TI The application of dielectric retrieval algorithms for mapping soil salinity in a tropical coastal environment using airborne polarimetric SAR SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID MOISTURE ESTIMATION; SURFACE-ROUGHNESS; BARE SOIL; MICROWAVE; BACKSCATTER; MODEL AB The Alligator River Region of the Northern Territory, Australia, is identified as a region particularly susceptible to saltwater intrusion into systems dominated by freshwater processes. Attempts have been made by the Parks and Wildlife Commission of the NT to restrict the intrusion by creating physical earth barrages. In this study the use of Airborne Polarimetric Synthetic Aperture Radar for mapping soil salinity is examined. Three dielectric retrieval algorithms, the Small Perturbation, Physical Optics, and Dubois models have been implemented, and the results of these were combined to retrieve an improved estimate of the magnitude of the imaginary part of the complex dielectric constant for soil salinity discrimination. An efficient data selection process was employed to allow application of these models in this natural environment. Vegetation correction to the small perturbation and physical optics models before combination with the Dubois model improved classification accuracy in the semivegetated areas. (C) 2001 Elsevier Science Inc. All rights reserved. C1 No Terr Univ, Sch Biol Environm & Chem Sci, Darwin, NT, Australia. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Bell, D (reprint author), No Terr Univ, Sch Biol Environm & Chem Sci, Darwin, NT, Australia. NR 25 TC 19 Z9 20 U1 3 U2 8 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 USA SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD MAR PY 2001 VL 75 IS 3 BP 375 EP 384 DI 10.1016/S0034-4257(00)00180-2 PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 475VU UT WOS:000171190900006 ER PT J AU Huemmrich, KF AF Huemmrich, KF TI The GeoSail model: a simple addition to the SAIL model to describe discontinuous canopy reflectance SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID RED-INFRARED SCATTERGRAMS; RADIATIVE-TRANSFER; PACIFIC NORTHWEST; PAR ABSORPTANCE; FOREST CANOPY; VEGETATION; OREGON AB The scattering from arbitrarily inclined leaves (SAIL) model was combined with the Jasinski geometric model to simulate canopy spectral reflectance and fraction of absorbed photosynthetically active radiation (f(APAR),) for discontinuous canopies. This model is called the GeoSail model. Tree shapes are described by cylinders or cones distributed over a plane. Spectral reflectance and transmittance of trees are calculated from the SAIL model to determine the reflectance of the three components of the geometric model: illuminated canopy, illuminated background, and shadowed background. Although the GeoSail model is relatively simple, calculations of canopy reflectance and fraction of intercepted photosynthetically active radiation (F-IPAR) compared well with measurements collected in field experiments in forests in Minnesota and Oregon. (C) 2001 Elsevier Science Inc. All rights reserved. C1 Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, Catonsville, MD USA. RP Huemmrich, KF (reprint author), NASA, Goddard Space Flight Ctr, Code 923-4, Greenbelt, MD 20771 USA. NR 27 TC 88 Z9 97 U1 2 U2 18 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 MAR PY 2001 VL 75 IS 3 BP 423 EP 431 DI 10.1016/S0034-4257(00)00184-X PG 9 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 475VU UT WOS:000171190900010 ER PT J AU Peele, AG Irving, THK Nugent, KA Mancini, DC Christenson, TR Petre, R Brumby, SP Priedhorsky, WC AF Peele, AG Irving, THK Nugent, KA Mancini, DC Christenson, TR Petre, R Brumby, SP Priedhorsky, WC TI LIGA for lobster: First observation of lobster-eye focusing from lithographically produced optics SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID X-RAY OPTICS; CHANNEL-CAPILLARY ARRAYS AB The prospect of making a lobster-eye telescope is drawing closer with recent developments in the manufacture of microchannel-plate optics. This would lead to an x-ray all-sky monitor with vastly improved sensitivity and resolution over existing and other planned instruments. We consider a new approach, using deep etch x-ray lithography, to making a lobster-eye lens that offers certain advantages even over microchannel-plate technology. (C) 2001 American Institute of Physics. C1 Univ Melbourne, Sch Phys, Parkville, Vic 3010, Australia. Argonne Natl Lab, Argonne, IL 60439 USA. Sandia Natl Labs, Photon & Microfabricat Dept, Albuquerque, NM 87185 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Los Alamos Natl Lab, Nonproliferat & Int Secur Div, Los Alamos, NM 87545 USA. RP Peele, AG (reprint author), Univ Melbourne, Sch Phys, Parkville, Vic 3010, Australia. RI Nugent, Keith/J-2699-2012; Nugent, Keith/I-4154-2016; OI Nugent, Keith/0000-0003-1522-8991; Nugent, Keith/0000-0002-4281-3478; Priedhorsky, William/0000-0003-0295-9138 NR 17 TC 10 Z9 10 U1 0 U2 2 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 MAR PY 2001 VL 72 IS 3 BP 1843 EP 1849 DI 10.1063/1.1347377 PG 7 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 406BK UT WOS:000167194900038 ER PT J AU Martinez-Fernandez, J Valera-Feria, FM Dominguez-Rodriguez, A Singh, M AF Martinez-Fernandez, J Valera-Feria, FM Dominguez-Rodriguez, A Singh, M TI Microstructure and high temperature compressive mechanical behavior of biomophic silicon carbide-based ceramics SO REVISTA DE METALURGIA LA Spanish DT Article; Proceedings Paper CT 7th National Congress on the Mechanical Properties of Solids CY JUN 27-30, 2000 CL SEGOVIA, SPAIN DE silicon carbide; bomorphic; high temperature; microstructure ID REACTIVE MELT INFILTRATION; RFSC CERAMICS; ALLOYS; WOOD AB Environment conscious ceramics (ecoceramics) are a new class of ceramic materials fabricated from natural wood (a renewable source). The affordable, net shape ceramics are fabricated by pyrolysis and molten silicon infiltration of wood preforms. The resulting materials have complex microstructure and multifunctional properties. The microstructure before and after high temperature plastic deformation was studied by Scanning electron microscopy. These ceramics present regions of silicon and silicon carbide that follow the fibrous microstructure of the wood selected, resulting in a structure that resembles a continuos fiber composite. This structure results in very good mechanical properties as the evolutionary process has perfected it. C1 Univ Sevilla, Dept Fis Mat Condensada, E-41080 Seville, Spain. NASA, Glenn Res Ctr, Ceram Branch, Cleveland, OH 44135 USA. RP Martinez-Fernandez, J (reprint author), Univ Sevilla, Dept Fis Mat Condensada, Apdo 1065, E-41080 Seville, Spain. NR 10 TC 0 Z9 1 U1 0 U2 0 PU CENIM PI MADRID PA AVDA. GREGORIO DEL AMO, 8, 28040 MADRID, SPAIN SN 0034-8570 J9 REV METAL MADRID JI Rev. Metal. PD MAR-APR PY 2001 VL 37 IS 2 BP 295 EP 298 PG 4 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA 487XE UT WOS:000171903700042 ER PT J AU Gottlieb, S Shu, CW Tadmor, E AF Gottlieb, S Shu, CW Tadmor, E TI Strong stability-preserving high-order time discretization methods SO SIAM REVIEW LA English DT Article DE strong stability preserving; Runge-Kutta methods; multistep methods; high-order accuracy; time discretization ID HYPERBOLIC CONSERVATION-LAWS; HIGH-RESOLUTION SCHEMES; FINITE-ELEMENT METHOD; RUNGE-KUTTA SCHEMES; APPROXIMATIONS AB In this paper we review and further develop a class of strong stability-preserving (SSP) high-order time discretizations for semidiscrete method of lines approximations of partial differential equations. Previously termed TVD (total variation diminishing) time discretizations, these high-order time discretization methods preserve the strong stability properties of first-order Euler time stepping and have proved very useful, especially in solving hyperbolic partial differential equations. The new developments in this paper include the construction of optimal explicit SSP linear Runge-Kutta methods, their application to the strong stability of coercive approximations, a systematic study of explicit SSP multistep methods for nonlinear problems, and the study of the SSP property of implicit Runge-Kutta and multistep methods. C1 Univ Massachusetts, Dept Math, Dartmouth, MA 02747 USA. Brown Univ, Div Appl Math, Providence, RI 02912 USA. Univ Calif Los Angeles, Dept Math, Los Angeles, CA 90095 USA. NASA, Langley Res Ctr, ICASE, Hampton, VA 23681 USA. RP Univ Massachusetts, Dept Math, Dartmouth, MA 02747 USA. EM sgottliebe@umassd.edu; shu@cfm.brown.edu; tadmor@math.ucla.edu RI Shu, Chi-Wang/A-3216-2013; OI Shu, Chi-Wang/0000-0001-7720-9564; Tadmor, Eitan/0000-0001-7424-6327 NR 23 TC 702 Z9 727 U1 6 U2 31 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 USA SN 0036-1445 EI 1095-7200 J9 SIAM REV JI SIAM Rev. PD MAR PY 2001 VL 43 IS 1 BP 89 EP 112 DI 10.1137/S003614450036757X PG 24 WC Mathematics, Applied SC Mathematics GA 409CC UT WOS:000167366100005 ER PT J AU Nizeyimana, EL Petersen, GW Imhoff, ML Sinclair, HR Waltman, SW Reed-Margetan, DS Levine, ER Russo, JM AF Nizeyimana, EL Petersen, GW Imhoff, ML Sinclair, HR Waltman, SW Reed-Margetan, DS Levine, ER Russo, JM TI Assessing the impact of land conversion to urban use on soils with different productivity levels in the USA SO SOIL SCIENCE SOCIETY OF AMERICA JOURNAL LA English DT Article ID CITY LIGHTS; AGRICULTURAL LAND; UNITED-STATES; URBANIZATION; RESOURCES; FARMLAND AB There has been increased public concern in the USA over the longterm impact of urbanization on the available land used to produce food, feed, and fiber, Concern that urban use of highly productive soils may threaten our food security and sustainability has been debated for nearly three decades. This study was primarily initiated to compare different soil productivity classes in terms of areas and proportion of land converted to urban uses in the USA. The methodology consisted of analyzing data resulting from a geographic information system (GIS) overlay of urban land use maps derived from the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) nighttime imagery and layers of potential soil productivity. Soil productivity distributions were obtained using the Soil Rating for Plant Growth (SRPG) model based primarily on soil and landscape parameters contained in the State Soil Geographic (STAT-SGO) database, Currently, the urban land use covers approximate to3% of the conterminous USA and is primarily on areas that were originally of low and moderate soil productivity. Only 6% of the total land under urbanization had consisted of highly productive soils. However, land with highly productive soils, roughly 3% of the total U,S, area, has a higher level of urbanization (5%) than that of any other soil productivity category. States differ in the areas and proportion of land converted to urban uses in each soil productivity class. These results are a first step in determining the current status of soil resources in relation to urbanization and should be interpreted according to the scale and resolution of data sources and assumptions made in the soil productivity modeling. C1 Penn State Univ, Coll Agr, Dept Agron, University Pk, PA 16802 USA. Penn State Univ, Environm Resources Res Inst, University Pk, PA 16802 USA. NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20772 USA. USDA, Natl Soil Survey Ctr, NRCS, Lincoln, NE 68508 USA. Iowa State Univ Sci & Technol, Stat Lab, Ames, IA 50011 USA. ZedX Inc, Bellafonte, PA 16823 USA. RP Nizeyimana, EL (reprint author), Penn State Univ, Coll Agr, Dept Agron, 101 Land & Water Res Bldg, University Pk, PA 16802 USA. NR 42 TC 38 Z9 50 U1 1 U2 26 PU SOIL SCI SOC AMER PI MADISON PA 677 SOUTH SEGOE ROAD, MADISON, WI 53711 USA SN 0361-5995 J9 SOIL SCI SOC AM J JI Soil Sci. Soc. Am. J. PD MAR-APR PY 2001 VL 65 IS 2 BP 391 EP 402 PG 12 WC Soil Science SC Agriculture GA 445NQ UT WOS:000169464300017 ER PT J AU Chang, KY AF Chang, KY TI Deep space 1 spacecraft vibration qualification testing SO SOUND AND VIBRATION LA English DT Article AB The environmental qualification program for the Deep Space 1 spacecraft included a force-limited random vibration test in two axes. A semi-empirical force limit procedure was used to derive force limits for the test. The results of the test show that the acceleration inputs measured near the feet of a number of spacecraft mounted instruments reached their assembly random vibration test specifications, Also, several major structural elements of the spacecraft reached their flight limit loads during the spacecraft vibration test. Test results, as well as lessons learned, from those tests will be discussed in this article. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chang, KY (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 2 TC 0 Z9 0 U1 1 U2 3 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 MAR PY 2001 VL 35 IS 3 BP 14 EP 17 PG 4 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 420ZY UT WOS:000168037600004 ER PT J AU Laubscher, SAB Ashwal, LD Tredoux, M Zolensky, ME Loock, JC Praekelt, HE AF Laubscher, SAB Ashwal, LD Tredoux, M Zolensky, ME Loock, JC Praekelt, HE TI Merweville: A new South African chondritic meteorite SO SOUTH AFRICAN JOURNAL OF GEOLOGY LA English DT Article AB We report petrologic, petrographic and chemical data for a newly discovered meteorite specimen from South Africa. The 7.04 kg specimen was found in ca. 1977 on the farm Waterval 64, about 30 km from the town of Merweville (similar to375 km northeast of Cape Town). Our research group confirmed the identity of the stone as a meteorite in 1997, and obtained a similar to1.5 kg portion for study and classification. Externally, the specimen shows a few reginaglypts and a reddish-brown, weathered fusion crust. The sawn internal surfaces show that terrestrial weathering effects, which tender a dark brownish colour to the specimen, have penetrated up to 4 to 5 cm into the meteorite. The relatively unweathered interior is light orange-brown in colour. Petrographically, the specimen shows,I dominantly recrystallised texture, with a few recognisable chondrules or chondrule fragments. Shock stage is estimated at S2, and weathering grade is W2. Microprobe analyses yield: olivine (Fa(23.32 +/- 0.612), PMD = 0.52, n = 13), orthopyroxene (Fs(20.59 +/- 0.54), n = 15), kamacite (Ni = 6.48 +/- 0.24 wt.%, Co = 0.94 +/- 0.14 wt.% n = 15), taenite (Ni = 28.9 +/- 2.3 wt.%, Co = 0.29 +/- 0.08 wt.%, n = 3), troilite (Ni = 0.10 +/- 0.11 wt.%, n = 17) and chromite (Cr/(Cr+Al) = 0.860 +/- 0.003, n = 4). No recognisable feldspar or glass is present in our thin sections of Merweville. The dominantly recrystallised but partial preservation of chondrules, apparent absence of glass, and the relative uniformity of olivine and pyroxene compositions are all consistent with classification of Merweville as petrologic type 5. Chemical and mineralogical data for the "unweathered" portion of the meteorite fall best within the L group. We conclude that Merweville is an L5 chondrite. This new specimen increases the inventory of known South African meteorites to a total of 48. C1 Rand Afrikaans Univ, Dept Geol, ZA-2006 Auckland Pk, South Africa. Univ Cape Town, Dept Geol Sci, ZA-7700 Rondebosch, South Africa. NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. Univ Orange Free State, Dept Geol, ZA-9300 Bloemfontein, South Africa. RP Laubscher, SAB (reprint author), Council Geosci, Private Bag X112, ZA-0001 Pretoria, South Africa. NR 18 TC 0 Z9 0 U1 0 U2 0 PU GEOLOGICAL SOC SOUTH AFRICA PI MARSHALLTOWN PA PO BOX 61809, MARSHALLTOWN 2107, SOUTH AFRICA SN 0371-7208 J9 S AFR J GEOL JI S. Afr. J. Geol. PD MAR PY 2001 VL 104 IS 1 BP 69 EP 76 DI 10.2113/104.1.69 PG 8 WC Geology SC Geology GA 580TW UT WOS:000177252500006 ER PT J AU Sobieszczanski-Sobieski, J Kodiyalam, S AF Sobieszczanski-Sobieski, J Kodiyalam, S TI BLISS/S: a new method for two-level structural optimization SO STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION LA English DT Article DE structures; optimization; bi-level; two-level; multilevel; nonlinear programming AB The paper describes a two-level method for structural optimization for a minimum weight under the local strength and displacement constraints. The method divides the optimization task into separate optimizations of the individual substructures (in the extreme, the individual components) coordinated by the assembled structure optimization. The substructure optimizations use local cross-sections as design variables and satisfy the highly nonlinear local constraints of strength and buckling. The design variables in the assembled structure optimization govern the structure overall shape and handle the displacement constraints. The assembled structure objective function is the objective in each of the above optimizations. The substructure optimizations are linked to the assembled structure optimization by the sensitivity derivatives. The method was derived from a previously reported two-level optimization method for engineering systems, e.g. aerospace vehicles, that comprise interacting modules to be optimized independently, coordination provided by a system-level optimization. This scheme was adapted to structural optimization by treating each substructure as a module in a system, and using the standard finite element analysis as the system analysis. A numerical example, a hub structure framework, is provided to show the new method agreement with a standard, no-decomposition optimization. The new method advantage lies primarily in the autonomy of the individual substructure optimization that enables concurrency of execution to compress the overall task elapsed time. The advantage increases with the magnitude of that task. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Lockheed Martin Space Syst Co, Adv Technol Ctr, Sunnyvale, CA 94089 USA. RP Sobieszczanski-Sobieski, J (reprint author), NASA, Langley Res Ctr, MS 139, Hampton, VA 23681 USA. NR 13 TC 17 Z9 18 U1 1 U2 11 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1615-147X J9 STRUCT MULTIDISCIP O JI Struct. Multidiscip. Optim. PD MAR PY 2001 VL 21 IS 1 BP 1 EP 13 PG 13 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary; Mechanics SC Computer Science; Engineering; Mechanics GA 414JA UT WOS:000167662100001 ER PT J AU Klimeck, G Bowen, RC Boykin, TB AF Klimeck, G Bowen, RC Boykin, TB TI Strong wavevector dependence of hole transport in heterostructures SO SUPERLATTICES AND MICROSTRUCTURES LA English DT Article DE resonant tunneling; holes; anisotropy; transport ID RESONANT-TUNNELING-DIODE; CURRENT-VOLTAGE CALCULATIONS; TIGHT-BINDING PARAMETERS; INTERFACE ROUGHNESS; SEMICONDUCTOR STRUCTURES; QUANTUM-WELLS; SPIN-ORBIT; BAND; APPROXIMATION; SIMULATIONS AB Heterostructures such as resonant tunneling diodes, quantum well photodetectors and lasers, and cascade lasers break the symmetry of the crystalline lattice. Such break in lattice symmetry causes a strong interaction of heavy-, light- and split-off hole bands. A resonant tunneling diode is used as a vehicle to study hole transport in heterostructures including the subband dispersion transverse to the main transport direction. Four key findings are demonstrated: (I)the heavy and light hole interaction is shown to be strong enough to result in dominant current flow off the Gamma zone center (more holes flow through the structure at an angle than straight through), (2) explicit inclusion of the transverse momentum in the current integration is needed, (3) most of the current flow is due to injection from heavy holes in the emitter, and (4) the dependence on the angle phi of the transverse momentum k is weak. Two bandstructure models are utilized to demonstrate the underlying physics: (1) independent/uncoupled heavy-, light- and split-off bands, and (2) second-nearest neigh bor sp3s* tight-binding model. Current-voltage (I-V) simulations including explicit integration of the total energy E, transverse momentum /k/ and transverse momentum angle phi are analyzed. An analytic formula for the current density J(k) as a function of transverse momentum k is derived and utilized to explain the three independent mechanisms that generate off-zone-center current flow: (1) nonmonotonic (electron-like) hole dispersion, (2) different quantum well and emitter effective masses, and (3) momentum-dependent quantum well coupling strength. The analytic expression is also used to generate a complete I-V characteristic that compares well to the full numerical solution. The Fermi level and temperature dependence on the I-V is examined. Finally a simulation is compared to experimental data. (C) 2001 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Alabama, Dept Elect & Comp Engn, Huntsville, AL 35899 USA. Univ Alabama, LICOS, Huntsville, AL 35899 USA. RP Klimeck, G (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Klimeck, Gerhard/A-1414-2012 OI Klimeck, Gerhard/0000-0001-7128-773X NR 44 TC 16 Z9 16 U1 0 U2 0 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 MAR PY 2001 VL 29 IS 3 BP 187 EP 216 DI 10.1006/spmi.2000.0973 PG 30 WC Physics, Condensed Matter SC Physics GA 416HU UT WOS:000167774900001 ER PT J AU Nicogossian, AE Pober, DF Roy, SA AF Nicogossian, AE Pober, DF Roy, SA TI Evolution of telemedicine in the space program and earth applications SO TELEMEDICINE JOURNAL AND E-HEALTH LA English DT Article AB Remote monitoring of crew spacecraft, and environmental health has always been an integral part of the National Aeronautics and Space Administration's (NASA's) operations. Crew safety and mission success face a number of challenges in outerspace, including physiological adaptations to microgravity, radiation exposure, extreme temperatures and vacuum, and psychosocial reactions to space flight. The NASA effort to monitor and maintain crew health, system performance, and environmental integrity in space flight is a sophisticated and coordinated program of telemedicine combining cutting-edge engineering with medical expertise. As missions have increased in complexity, NASA telemedicine capabilities have grown apace, underlying its role in the field. At the same time, the terrestrial validation of telemedicine technologies to bring healthcare to remote locations provides feedback, improvement, and enhancement of the space program. As NASA progresses in its space exploration program, astronauts will join missions lasting months, even years, that take them millions of miles from home. These long-duration missions necessitate further technological breakthroughs in tele-operations and autonomous technology. Earth-based monitoring will no longer be realtime, requiring telemedicine capabilities to advance with future explorers as they travel deeper into space. The International Space Station will serve as a testbed for the telemedicine technologies to enable future missions as well as improve the quality of healthcare delivery on Earth. C1 NASA HQ, Off Chief Hlth & Med Officier, Washington, DC 20024 USA. Futron Corp, Bethesda, MD USA. RP Nicogossian, AE (reprint author), NASA HQ, Off Chief Hlth & Med Officier, Code AM,300 E St SW, Washington, DC 20024 USA. NR 25 TC 22 Z9 24 U1 0 U2 8 PU MARY ANN LIEBERT INC PUBL PI LARCHMONT PA 2 MADISON AVENUE, LARCHMONT, NY 10538 USA SN 1530-5627 J9 TELEMED J E-HEALTH JI Telemed. J. e-Health PD SPR PY 2001 VL 7 IS 1 BP 1 EP 15 DI 10.1089/153056201300093813 PG 15 WC Health Care Sciences & Services SC Health Care Sciences & Services GA 423YF UT WOS:000168204800001 PM 11321704 ER PT J AU Chen, JP Lin, RF AF Chen, JP Lin, RF TI Numerical simulation of contrail microphysical and radiative properties SO TERRESTRIAL ATMOSPHERIC AND OCEANIC SCIENCES LA English DT Article DE contrail; microphysics; radiative forcing ID CIRRUS CLOUDS; TROPICAL CIRRUS; HEATING RATES; MODEL; PARAMETERIZATION; ANVILS; GROWTH AB The late-dispersion phase of contrails is simulated with a high-resolution cloud model in which the size distributions of ice crystals are explicitly computed. The cloud optical properties derived from this model are then used to compute the cloud reflectivity using the Monte Carlo method for the shortwave radiation, as well as the outgoing longwave radiative fluxes at the top of atmosphere using the absorption approximation method. Simulations for both the dissipating and persistent contrail scenarios in typical ambient conditions over Taiwan showed that the evolution of contrail morphology is critically controlled by the ambient humidity. Also, contrails may effectively alter the local radiative budget, more so for the persistent contrails than the dissipating contrails. C1 Natl Taiwan Univ, Dept Atmospher Sci, Taipei 10764, Taiwan. RP Lin, RF (reprint author), Univ Maryland, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21201 USA. RI Chen, Jen-Ping/F-2947-2010 OI Chen, Jen-Ping/0000-0003-4188-6189 NR 42 TC 2 Z9 2 U1 0 U2 0 PU CHINESE GEOSCIENCE UNION PI TAIPEI PA PO BOX 23-59, TAIPEI 10764, TAIWAN SN 1017-0839 J9 TERR ATMOS OCEAN SCI JI Terr. Atmos. Ocean. Sci. PD MAR PY 2001 VL 12 IS 1 BP 137 EP 154 PG 18 WC Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences; Oceanography SC Geology; Meteorology & Atmospheric Sciences; Oceanography GA 423MP UT WOS:000168180300008 ER PT J AU MacDougall, PJ Henze, CE AF MacDougall, PJ Henze, CE TI Identification of molecular reactive sites with an interactive volume rendering tool SO THEORETICAL CHEMISTRY ACCOUNTS LA English DT Article; Proceedings Paper CT Symposium on Chemical Bonding - State of the Art in Conceptual Quantum Chemistry CY JUN 01-04, 2000 CL LA COLLESUR LOUP, FRANCE DE laplacian; hydrogen bonding; volume rendering ID CHARGE-DENSITY; HYDROGEN-BOND; ELECTRON-DENSITY; LAPLACIAN; CRYSTALS; PREDICTION; COMPLEXES; ATOMS; IONS AB A new molecular visualization tool is presented, EVolVis tan abbreviation of electronic volume visualizer). This software enables the user to interactively explore a molecule's electronic charge density for topological features. Using novel volume rendering techniques, the entire molecule can be probed without obstruction by opaque surfaces or preselection of specific orbitals or contours. Menus with sliding scales permit various ranges of the function of interest to be examined interactively. We have investigated the Laplacian of the electronic charge density calculated for several biomolecules that contain a variety of reactive sites: cisplatin, penamecillin and isomers of nitrogen bases from DNA, EVolVis is useful in identifying inner-shell features (cisplatin)l polar, nonpolar and aromatic regions (penamecillin), hydrogen-bonding sites of varying strength (nitrogen bases and penamecillin:) and other reactive sites (strained heterocycle in penamecillin). C1 Middle Tennessee State Univ, Dept Chem, Murfreesboro, TN 37132 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP MacDougall, PJ (reprint author), Middle Tennessee State Univ, Dept Chem, Murfreesboro, TN 37132 USA. RI MacDougall, Preston/N-2515-2016 OI MacDougall, Preston/0000-0002-0403-000X NR 39 TC 14 Z9 14 U1 0 U2 1 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 1432-881X J9 THEOR CHEM ACC JI Theor. Chem. Acc. PD MAR PY 2001 VL 105 IS 4-5 BP 345 EP 353 DI 10.1007/s002140000225 PG 9 WC Chemistry, Physical SC Chemistry GA 427KR UT WOS:000168403800011 ER PT J AU Spina, AP AF Spina, AP TI Incubation discharge and aspects of brown trout population dynamics SO TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY LA English DT Article ID SALMON SALMO-SALAR; DOWNSTREAM DISPLACEMENT; FISH ASSEMBLAGE; TRUTTA-L; STREAM; DENSITY; DEPTHS; FLOODS; SCOUR; RIVER AB Data from an 11-year study of a population of brown trout Salmo trutta showed that peak discharge at the time of incubation was inversely related to year-class strength (density of young of the year estimated in fall), which suggests that scouring of nests is a source of temporal variation in the density of young of the year. Relationships between cohort (individuals spawned the same year) age-groups provide a clue that discharge related year-class strength might influence the population dynamics of a year-class over time. C1 Entrix Inc, Walnut Creek, CA 94594 USA. RP Spina, AP (reprint author), Natl Marine Fisheries Serv, 501 W Ocean Blvd,Suite 4200, Long Beach, CA 90802 USA. EM anthony.spina@noaa.gov NR 43 TC 30 Z9 30 U1 1 U2 2 PU TAYLOR & FRANCIS INC PI PHILADELPHIA PA 530 WALNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA SN 0002-8487 EI 1548-8659 J9 T AM FISH SOC JI Trans. Am. Fish. Soc. PD MAR PY 2001 VL 130 IS 2 BP 322 EP 327 DI 10.1577/1548-8659(2001)130<0322:IDAAOB>2.0.CO;2 PG 6 WC Fisheries SC Fisheries GA 437GW UT WOS:000168984800011 ER PT J AU Casasent, D Talukder, A Keagy, P Schatzki, T AF Casasent, D Talukder, A Keagy, P Schatzki, T TI Detection and segmentation of items in X-ray imagery SO TRANSACTIONS OF THE ASAE LA English DT Article DE blob coloring; image processing; morphological processing; watershed transform; segmentation; detection; x-ray sensors ID WATERSHED ALGORITHMS; MACHINE RECOGNITION; DAMAGE; APPLES; NUTS AB Processing of real-time X-ray images of randomly oriented and touching pistachio nuts for product inspection is considered. Processing to isolate individual nuts (segmentation) is emphasized. The processing consisted of a blob coloring algorithm, filters, and watershed transforms to segment touching nuts, and morphological processing to produce an image of only the nutmeat. Each operation is detailed and quantitative data for each are presented. These techniques are useful for many different product inspection problems in agriculture and other areas. C1 Carnegie Mellon Univ, Dept Elect & Comp Engn, Pittsburgh, PA 15213 USA. CALTECH, Jet Prop Lab, Pasadena, CA USA. Agr Res Serv, Albany, CA USA. RP Casasent, D (reprint author), Carnegie Mellon Univ, Dept Elect & Comp Engn, Pittsburgh, PA 15213 USA. NR 21 TC 14 Z9 14 U1 1 U2 3 PU AMER SOC AGRICULTURAL ENGINEERS PI ST JOSEPH PA 2950 NILES RD, ST JOSEPH, MI 49085-9659 USA SN 0001-2351 J9 T ASAE JI Trans. ASAE PD MAR-APR PY 2001 VL 44 IS 2 BP 337 EP 345 PG 9 WC Agricultural Engineering SC Agriculture GA 467UX UT WOS:000170723100018 ER PT J AU De, SR Heaney, PJ Vicenzi, EP Wang, JH AF De, SR Heaney, PJ Vicenzi, EP Wang, JH TI Chemical heterogeneity in carbonado, an enigmatic polycrystalline diamond SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article DE carbonado; C-13/C-12; secondary ion mass spectroscopy; cathodoluminescence; nitrogen ID CHICXULUB CRATER; SILICON-CARBIDE; IMPACT CRATER; MELT ROCK; ORIGIN; CATHODOLUMINESCENCE; AGGREGATION; DIFFUSION; DEFECTS; GROWTH AB Carbonade, a polycrystalline variety of diamond, is characterized by unusual carbon isotope compositions with bulk delta C-13 values clustered tightly between -23 and -30 parts per thousand (relative to PDB). These values are significantly lighter than harzburgitic diamond (with a range in delta C-13 from -1 to -10 parts per thousand) and fall near the lower extreme for eclogitic diamond (ranging from +3 to -34 parts per thousand). In combination with textural and inclusion data, these isotopic compositions have led scientists to question whether carbonade originated in the mantle or in the crust. Previous studies of carbonade have revealed a bimodal grain size distribution that correlates with cathodoluminescence (CL) emissions. We believe that these textures result from a two-step growth process, and we have obtained additional chemical evidence that supports the identification of two distinct crystal populations. Ion microprobe analyses of a Central African carbonade reveal a bimodal distribution of delta C-13 values of -24 and -26 parts per thousand (with an instrumental precision of +/- 0.29 parts per thousand). Secondary ion mass spectrometry analyses also demonstrate that this delta C-13 distribution coincides with variations in nitrogen abundance, and both of these chemical zonations correlate with CL emission signatures. A one-dimensional analysis of self-diffusion of carbon in diamond suggests that isotopic homogenization occurs extremely slowly, even under upper mantle conditions. Whereas the microscale distribution of carbon isotopes in carbonade does not constrain the temperature, pressure or time of carbonade formation, it does provide a geochemical signature that recorded the dynamics of the growth process. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Carnegie Inst Washington, Dept Terr Magnetism, Washington, DC 20015 USA. Smithsonian Inst, Natl Museum Amer Hist, Dept Mineral Sci, Washington, DC 20560 USA. Penn State Univ, Dept Geosci, University Pk, PA 16802 USA. Princeton Univ, Dept Geosci, Princeton, NJ 08544 USA. RP De, SR (reprint author), NASA, Ames Res Ctr, Exobiol Branch, MS-239-4, Moffett Field, CA 94035 USA. RI Wang, Jianhua/D-6500-2011 OI Wang, Jianhua/0000-0002-7671-2413 NR 67 TC 24 Z9 25 U1 2 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD FEB 28 PY 2001 VL 185 IS 3-4 BP 315 EP 330 DI 10.1016/S0012-821X(00)00369-1 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 405WC UT WOS:000167182700006 ER PT J AU Oglesby, RJ Marshall, S Roads, JO Robertson, FR AF Oglesby, RJ Marshall, S Roads, JO Robertson, FR TI Diagnosing warm season precipitation over the GCIP region from a GCM and reanalysis SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MISSISSIPPI-RIVER BASIN; INTERNATIONAL PROJECT GCIP; COMMUNITY-CLIMATE-MODEL; ENERGY BUDGETS; SUMMER FLOODS; UNITED-STATES; SURFACE-WATER; 1988 DROUGHT; NCAR; TEMPERATURE AB A 45-year simulation using a global general circulation model (GCM), the National Center for Atmospheric Research (NCAR) Community Climate Model version 3 (CCM3), forced with observed sea surface temperatures (SST), and 39 years of global National Centers for Environmental Prediction (NCEP) reanalyses were analyzed to determine Mississippi River basin warm season (May, June, July or MJJ) wet and dry year composites in the water and energy budgets. Years that have increased MJJ soil moisture over the Global Energy and Water Cycle Experiment (GEWEX) Continental-Scale International Project (GCIP) region also have high precipitation, lower surface temperature, decreased Bowen ratio, and reduced 500-hPa geopotential height (essentially reduced MJJ ridging). The reverse is true for years that have reduced MJJ soil moisture. Wet years are also accompanied by a general increase in moisture transport from the Gulf of Mexico into the central United States. There is some indication (though weaker) that soil moisture may then affect precipitation and other quantities and be affected in turn by 500-hPa geopotential heights. The correlations are somewhat low, however, demonstrating the difficulty in providing definitive physical links between the remote and local effects. Analysis of two individual years with an extreme wet event (1993) and an extreme dry event (1988) yields the same general relationships as with the wet and dry composites. The composites from this study are currently serving as the basis for a series of experiments aimed at determining the predictability of the land surface and remote SST on the Mississippi River basin and other large-scale river basins. C1 George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35805 USA. Univ N Carolina, Dept Geog & Earth Sci, Charlotte, NC 28223 USA. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. Purdue Univ, Dept Earth & Atmospher Sci, W Lafayette, IN 47907 USA. RP Oglesby, RJ (reprint author), George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, 320 Sparkman Dr, Huntsville, AL 35805 USA. NR 37 TC 7 Z9 7 U1 1 U2 4 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 FEB 27 PY 2001 VL 106 IS D4 BP 3357 EP 3369 DI 10.1029/2000JD900538 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 405JE UT WOS:000167155600004 ER PT J AU Mickley, LJ Jacob, DJ Rind, D AF Mickley, LJ Jacob, DJ Rind, D TI Uncertainty in preindustrial abundance of tropospheric ozone: Implications for radiative forcing calculations SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; GLOBAL LIGHTNING DISTRIBUTIONS; CHEMICAL-TRANSPORT MODEL; STRATOSPHERIC OZONE; SURFACE OZONE; CHEMISTRY; CLIMATE; SIMULATION; EMISSIONS; NOX AB Recent model calculations of the global mean radiative forcing from tropospheric ozone since preindustrial times fall in a relatively narrow range, from 0.3 to 0.5 W m(-2) These calculations use preindustrial ozone fields that overestimate observations available from the turn of the nineteenth century. Although there may be calibration problems with the observations, uncertainties in model estimates of preindustrial natural emissions must also be considered. We show that a global three-dimensional model of tropospheric chemistry with reduced NO(x) emissions from lightning (1-2 Tg N yr(-1)) and soils (2 Tg N yr(-1)) and increased emissions of biogenic hydrocarbons can better reproduce the nineteenth century observations. The resulting global mean radiative forcing from tropospheric ozone since preindustrial times is 0.72-0.80 W m(-2), amounting to about half of the estimated CO(2) forcing. Reduction in the preindustrial lightning source accounts for two thirds of the increase in the ozone forcing. Because there is near-total titration of OH by isoprene in the continental boundary layer of the preindustrial atmosphere, isoprene and other biogenic hydrocarbons represent significant ozone sinks. The weak dr absent spring maximum in the nineteenth century observations of ozone is difficult to explain within our understanding of the natural ozone budget. Our results indicate that the uncertainty in computing radiative forcing from tropospheric ozone since preindustrial times is larger than is usually acknowledged. C1 Harvard Univ, Div Engn & Appl Sci, Cambridge, MA 02138 USA. Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA. Goddard Inst Space Studies, New York, NY 10025 USA. RP Mickley, LJ (reprint author), Harvard Univ, Div Engn & Appl Sci, 29 Oxford St, Cambridge, MA 02138 USA. EM ljm@io.harvard.edu RI Mickley, Loretta/D-2021-2012 OI Mickley, Loretta/0000-0002-7859-3470 NR 49 TC 67 Z9 68 U1 0 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 27 PY 2001 VL 106 IS D4 BP 3389 EP 3399 DI 10.1029/2000JD900594 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 405JE UT WOS:000167155600007 ER PT J AU Eck, TF Holben, BN Ward, DE Dubovik, O Reid, JS Smirnov, A Mukelabai, MM Hsu, NC O'Neill, NT Slutsker, I AF Eck, TF Holben, BN Ward, DE Dubovik, O Reid, JS Smirnov, A Mukelabai, MM Hsu, NC O'Neill, NT Slutsker, I TI Characterization of the optical properties of biomass burning aerosols in Zambia during the 1997 ZIBBEE field campaign SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID VEGETATION FIRES; SOUTHERN AFRICA; SMOKE PARTICLES; WATER-VAPOR; BRAZIL; IRRADIANCE; NETWORK; AERONET; MODEL; ABSORPTION AB The physical and optical properties of biomass burning aerosols in a savanna region in south central Africa (Zambia) were analyzed from measurements made during the Zambian International Biomass Burning Emissions Experiment (ZIBBEE) during August-September 1997. Due to the large spatial extent of African savannas and the high frequency of occurrence of burning in the annual dry seasons, characterization of the optical properties of the resultant biomass burning aerosols is important for the study of atmospheric radiative processes and for remote sensing of both surface and atmospheric properties in these regions. Aerosol Robotic Network Sun-sky radiometer spectral measurements of direct Sun observations and directional sky radiances were utilized to infer spectral aerosol optical depths (tau (a)), aerosol size distributions, and single-scattering albedos, During the primary ZIBBEE study period, which coincided with the peak period of biomass burning in the region, there was a high correlation between the measured tau (a) and the total column water vapor or precipitable water vapor (PWV), suggesting transport of smoke aerosol from regions with higher PWV. Size distribution retrievals of the biomass burning smoke show that the accumulation mode dominated and a comparison with smoke from Amazonia (Bolivia) shows a shift toward smaller particles for African savanna smoke. This may be the result of differences in mode of combustion (flaming versus smoldering), fuel type and moisture content, and the aging processes of the aerosol. The single-scattering albedo to,) of the aerosols were retrieved using several approaches, yielding average values of omega (o) at similar to 550 nm during ZIBBEE varying from similar to0.82 to similar to0.85, thus showing good agreement within the retrieval uncertainty of similar to0.03 of these methods. In general, omega (o) was relatively constant as a function of aerosol loading, with very little change occurring for tau (a) at 440 nm ranging from 0.7 to 1.7. African savanna smoke exhibits significantly higher absorption than smoke from Amazonian forested regions and also a greater rate of decrease of omega (o) with increasing wavelength. Variations in the spectral change of the Augstrom wavelength exponent were also investigated with respect to the degree of aerosol absorption and changes in the accumulation mode size distributions. C1 NASA, Goddard Space Flight Ctr, GEST Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA. Zambian Meteorol Dept, Mongu, Zambia. Univ Sherbrooke, CARTEL, Sherbrooke, PQ J1K 2R1, Canada. USDA, Forest Serv, Intermt Res Stn, Missoula, MT USA. Space & Naval Warfare Syst Ctr, Atmospher Propagat Branch, San Diego, CA USA. RP Eck, TF (reprint author), NASA, Goddard Space Flight Ctr, GEST Ctr, Biospher Sci Branch, Code 923, Greenbelt, MD 20771 USA. RI Dubovik, Oleg/A-8235-2009; Smirnov, Alexander/C-2121-2009; ECK, THOMAS/D-7407-2012; Hsu, N. Christina/H-3420-2013; Reid, Jeffrey/B-7633-2014 OI Dubovik, Oleg/0000-0003-3482-6460; Smirnov, Alexander/0000-0002-8208-1304; Reid, Jeffrey/0000-0002-5147-7955 NR 49 TC 134 Z9 136 U1 2 U2 13 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 FEB 27 PY 2001 VL 106 IS D4 BP 3425 EP 3448 DI 10.1029/2000JD900555 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 405JE UT WOS:000167155600010 ER PT J AU Rummel, JD AF Rummel, JD TI Planetary exploration in the time of astrobiology: Protecting against biological contamination SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID SUBSURFACE OCEAN; EUROPA; MARS; LIFE AB These are intriguing times in the exploration of other solar-system bodies. Continuing discoveries about life on Earth and the return of data suggesting the presence of liquid water environments on or under the surfaces of other planets and moons have combined to suggest the significant possibility that extraterrestrial life may exist in this solar system. Similarly, not since the Viking missions of the mid-1970s has there been as great an appreciation for the potential for Earth life to contaminate other worlds. Current plans for the exploration of the solar system include constraints intended to prevent biological contamination from being spread by solar-system exploration missions. C1 NASA, Washington, DC 20546 USA. RP Rummel, JD (reprint author), NASA, Washington, DC 20546 USA. NR 31 TC 52 Z9 52 U1 0 U2 3 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 FEB 27 PY 2001 VL 98 IS 5 BP 2128 EP 2131 DI 10.1073/pnas.061021398 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 407EH UT WOS:000167258900007 PM 11226203 ER PT J AU Lobitz, B Wood, BL Averner, MM McKay, CP AF Lobitz, B Wood, BL Averner, MM McKay, CP TI Use of spacecraft data to derive regions on Mars where liquid water would be stable SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID ATMOSPHERIC-PRESSURE; SURFACE; EVOLUTION AB Combining Viking pressure and temperature data with Mars Orbital Laser Altimeter topography data, we have computed the fraction of the martian year during which pressure and temperature allow for liquid water to be stable on the martian surface. We find that liquid water would be stable within the Hellas and Argyre basin and over the northern lowlands equatorward of about 40 degrees, The location with the maximum period of stable conditions for liquid water is in the southeastern portion of Utopia Planitia, where 34% of the year liquid water would be stable if it were present. Locations of stability appear to correlate with the distribution of valley networks. C1 NASA, Div Space Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Johnson Controls World Serv, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Div Earth Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. NASA, Fundamental Biol Off, Ames Res Ctr, Moffett Field, CA 94035 USA. RP McKay, CP (reprint author), NASA, Div Space Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 15 TC 28 Z9 30 U1 0 U2 1 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 FEB 27 PY 2001 VL 98 IS 5 BP 2132 EP 2137 DI 10.1073/pnas.031581098 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 407EH UT WOS:000167258900008 PM 11226204 ER PT J AU Ehrenfreund, P Glavin, DP Botta, O Cooper, G Bada, JL AF Ehrenfreund, P Glavin, DP Botta, O Cooper, G Bada, JL TI Extraterrestrial amino acids in Orgueil and Ivuna: Tracing the parent body of Cl type carbonaceous chondrites SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID MURCHISON METEORITE; ORGANIC-MOLECULES; SOLAR-SYSTEM; COMETARY; LINK AB Amino acid analyses using HPLC of pristine interior pieces of the Cl carbonaceous chondrites Orgueil and Ivuna have found that beta -alanine, glycine, and gamma -amino-n-butyric acid (ABA) are the most abundant amino acids in these two meteorites, with concentrations ranging from approximate to 600 to 2,000 parts per billion (ppb). Other alpha -amino acids such as alanine, alpha -ABA, alpha -aminoisobutyric acid (AIB), and isovaline are present only in trace amounts (<200 ppb). Carbon isotopic measurements of -alanine and glycine and the presence of racemic (D/L approximate to 1) alanine and beta -ABA in Orgueil suggest that these amino acids are extraterrestrial in origin. In comparison to the CM carbonaceous chondrites Murchison and Murray, the amino acid composition of the Cls is strikingly distinct, suggesting that these meteorites came from a different type of parent body, possibly an extinct comet, than did the CM carbonaceous chondrites. C1 Leiden Observ, Raymond & Beverly Sackler Lab Astrophys, NL-2300 RA Leiden, Netherlands. Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA. NASA, Ames Res Ctr, Exobiol Branch, Moffett Field, CA 94035 USA. RP Ehrenfreund, P (reprint author), Leiden Observ, Raymond & Beverly Sackler Lab Astrophys, POB 9513, NL-2300 RA Leiden, Netherlands. EM pascale@strw.leidenuniv.nl; jbada@ucsd.edu RI Glavin, Daniel/D-6194-2012 OI Glavin, Daniel/0000-0001-7779-7765 NR 36 TC 188 Z9 194 U1 1 U2 20 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 FEB 27 PY 2001 VL 98 IS 5 BP 2138 EP 2141 DI 10.1073/pnas.051502898 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 407EH UT WOS:000167258900009 PM 11226205 ER PT J AU Freund, F Staple, A Scoville, J AF Freund, F Staple, A Scoville, J TI Organic protomolecule assembly in igneous minerals SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID OXIDE SINGLE-CRYSTALS; NOMINALLY ANHYDROUS MINERALS; ION MASS-SPECTROMETRY; MAGNESIUM-OXIDE; HYDROTHERMAL CONDITIONS; THERMAL-DECOMPOSITION; CARBON SEGREGATION; GRAIN-BOUNDARY; SOLUTE CARBON; OLIVINE AB C-H stretching bands, nu (CH), in the infrared spectrum of single crystals of nominally high purity, of laboratory-grown MgO, and of natural upper mantle olivine, provide an "organic" signature that closely resembles the symmetrical and asymmetrical C-H stretching modes of aliphatic -CH(2) units. The nu (CH) bands indicate that H(2)O and CO(2), dissolved in the matrix of these minerals, converted to form H(2) and chemically reduced C, which in turn formed C-H entities, probably through segregation into defects such as dislocations. Heating causes the C-H bonds to pyrolyze and the nu (CH) hands to disappear, but annealing at 70 degreesC causes them to reappear within a few days or weeks. Modeling dislocations in MgO suggests that the segregation of C can lead to C(x) chains, x = 4, with the terminal C atoms anchored to the MgO matrix by bonding to two O(-). Allowing H(2) to react with such C(x) chains leads to [O(2)C(CH(2))(2)CO(2)] or similar precipitates. It is suggested that such C(x)-H(y)-O(z) entities represent protomolecules from which derive the short-chain carboxylic and dicarboxylic and the medium-chain fatty acids that have been solvent-extracted from crushed MgO and olivine single crystals, respectively. Thus, it appears that the hard, dense matrix of igneous minerals represents a medium in which protomolecular units can be assembled. During weathering of rocks, the protomolecular units turn into complex organic molecules. These processes may have provided stereochemically constrained organics to the early Earth that were crucial to the emergence of life. C1 NASA, Search Extraterr Intelligence Inst, Ames Res Ctr, Moffett Field, CA 94035 USA. Stanford Univ, Stanford, CA 94305 USA. Univ Kentucky, Lexington, KY 40506 USA. RP Freund, F (reprint author), NASA, Search Extraterr Intelligence Inst, Ames Res Ctr, MS 239-15, Moffett Field, CA 94035 USA. EM ffreund@mail.arc.nasa.gov NR 40 TC 9 Z9 10 U1 1 U2 3 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 FEB 27 PY 2001 VL 98 IS 5 BP 2142 EP 2147 DI 10.1073/pnas.061513298 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 407EH UT WOS:000167258900010 PM 11226206 ER PT J AU Thomas-Keprta, KL Clemett, SJ Bazylinski, DA Kirschvink, JL McKay, DS Wentworth, SJ Vali, H Gibson, EK McKay, MF Romanek, CS AF Thomas-Keprta, KL Clemett, SJ Bazylinski, DA Kirschvink, JL McKay, DS Wentworth, SJ Vali, H Gibson, EK McKay, MF Romanek, CS TI Truncated hexa-octahedral magnetite crystals in ALH84001: Presumptive biosignatures SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID MAGNETOTACTIC BACTERIA; IRON TRANSPORT; METEORITE; MARS; MAGNETOFOSSILS AB McKay et al. [(1996) Science 273, 924-930] suggested that carbonate globules in the meteorite ALH84001 contained the fossil remains of Martian microbes. We have characterized a subpopulation of magnetite (Fe3O4) crystals present in abundance within the Fe-rich rims of these carbonate globules. We find these Martian magnetites to be both chemically and physically identical to terrestrial, biogenically precipitated, intracellular magnetites produced by magnetotactic bacteria strain MV-1. Specifically, both magnetite populations are single-domain and chemically pure, and exhibit a unique crystal habit we describe as truncated hexaoctahedral. There are no known reports of inorganic processes to explain the observation of truncated hexa-octahedral magnetites in a terrestrial sample. In bacteria strain MV-1 their presence is therefore likely a product of Natural Selection. Unless there is an unknown and unexplained inorganic process on Mars that is conspicuously absent on the Earth and forms truncated hexaoctahedral magnetites, we suggest that these magnetite crystals in the Martian meteorite ALH84001 were likely produced by a biogenic process. As such, these crystals are interpreted as Martian magnetofossils and constitute evidence of the oldest life yet found. C1 Lockheed Martin, Houston, TX 77058 USA. Iowa State Univ, 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 Thomas-Keprta, KL (reprint author), Lockheed Martin, 2400 NASA Rd 1,Mail Code C23, Houston, TX 77058 USA. RI Vali, Hojatollah/F-3511-2012 OI Vali, Hojatollah/0000-0003-3464-9943 NR 27 TC 106 Z9 113 U1 4 U2 28 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 FEB 27 PY 2001 VL 98 IS 5 BP 2164 EP 2169 DI 10.1073/pnas.051500898 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 407EH UT WOS:000167258900014 PM 11226210 ER PT J AU Friedmann, EI Wierzchos, J Ascaso, C Winklhofer, M AF Friedmann, EI Wierzchos, J Ascaso, C Winklhofer, M TI Chains of magnetite crystals in the meteorite ALH84001: Evidence of biological origin SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article ID MAGNETOTACTIC BACTERIA; BIOMINERALIZATION; MAGNETOFOSSILS; MAGNETOSOMES; MINERALS; MARS AB The presence of magnetite crystal chains, considered missing evidence for the biological origin of magnetite in ALH84001 [Thomas-Keprta, K. L., Bazylinski, D. A., Kirschvink, J. L., Clemett, S. J., McKay, D. S., Wentworth, S. J., Vali, H., Gibson, E. K., Jr., & Romanek, C. S. (2000) Geochim. Cosmochim. Acta 64, 4049-4081], is demonstrated by high-power stereo backscattered scanning electron microscopy. Five characteristics of such chains (uniform crystal size and shape within chains, gaps between crystals, orientation of elongated crystals along the chain axis, flexibility of chains, and a halo that is a possible remnant of a membrane around chains), observed or inferred to be present in magnetotactic bacteria but incompatible with a nonbiological origin, are shown to be present. Although it is unlikely that magnetotactic bacteria were ever alive in ALH84001, decomposed remains of such organisms could have been deposited in cracks in the rock while it was still on the surface on Mars. C1 Florida State Univ, Dept Biol Sci, Tallahassee, FL 32306 USA. Univ Lleida, Serv Microscopia Elect, Lleida 25196, Spain. CSIC, Ctr Ciencias Medioambientales, E-28006 Madrid, Spain. Univ Munich, Inst Geophys, D-80333 Munich, Germany. RP Friedmann, EI (reprint author), NASA, Space Sci Div 245 3, Ames Res Ctr, Moffett Field, CA 94035 USA. RI Winklhofer, Michael/B-7349-2009; Ascaso, Carmen/F-5369-2011; Wierzchos, Jacek/F-7036-2011 OI Winklhofer, Michael/0000-0003-1352-9723; Ascaso, Carmen/0000-0001-9665-193X; Wierzchos, Jacek/0000-0003-3084-3837 NR 24 TC 78 Z9 85 U1 3 U2 19 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 FEB 27 PY 2001 VL 98 IS 5 BP 2176 EP 2181 DI 10.1073/pnas.051514698 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 407EH UT WOS:000167258900016 PM 11226212 ER PT J AU Hill, HGM Grady, CA Nuth, JA Hallenbeck, SL Sitko, ML AF Hill, HGM Grady, CA Nuth, JA Hallenbeck, SL Sitko, ML TI Constraints on nebular dynamics and chemistry based on observations of annealed magnesium silicate grains in comets and in disks surrounding Herbig Ae/Be stars SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Review ID PICTORIS CIRCUMSTELLAR DISK; INTERMEDIATE-MASS STARS; MAIN-SEQUENCE STARS; BETA-PICTORIS; SOLAR NEBULA; AE SYSTEMS; HD 163296; INTERPLANETARY DUST; ISO SPECTROSCOPY; SWS OBSERVATIONS AB Understanding dynamic conditions in the Solar Nebula is the key to prediction of the material to be found in comets. We suggest that a dynamic, large-scale circulation pattern brings processed dust and gas from the inner nebula back out into the region of cometesimal formation-extending possibly hundreds of astronomical units (AU) from the sun-and that the composition of comets is determined by a chemical reaction network closely coupled to the dynamic transport of dust and gas in the system. This scenario is supported by laboratory studies of Mg silicates and the astronomical data for comets and for protoplanetary disks associated with young stars, which demonstrate that annealing of nebular silicates must occur in conjunction with a large-scale circulation. Mass recycling of dust should have a significant eff ect on the chemical kinetics of the outer nebula by introducing reduced, gas-phase species produced in the higher temperature and pressure environment of the inner nebula, along with freshly processed grains with "clean" catalytic surfaces to the region of cometesimal formation. Because comets probably form throughout the lifetime of the Solar Nebula and processed (crystalline) grains are not immediately available for incorporation into the first generation of comets, an increasing fraction of dust incorporated into a growing comet should be crystalline olivine and this fraction can serve as a crude chronometer of the relative ages of comets. The formation and evolution of key organic and biogenic molecules in comets are potentially of great consequence to astrobiology. C1 NASA, Natl Opt Astron Observ, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. DuPont Co Inc, Cent Res & Dev, Wilmington, DE 19880 USA. Univ Cincinnati, Dept Phys, Cincinnati, OH 45221 USA. RP Hill, HGM (reprint author), NASA, Natl Opt Astron Observ, Goddard Space Flight Ctr, Code 691, Greenbelt, MD 20771 USA. EM hill@lepvax.gsfc.nasa.gov RI Nuth, Joseph/E-7085-2012 NR 84 TC 39 Z9 39 U1 1 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 FEB 27 PY 2001 VL 98 IS 5 BP 2182 EP 2187 DI 10.1073/pnas.051530998 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 407EH UT WOS:000167258900017 PM 11226213 ER PT J AU Choudhury, BJ AF Choudhury, BJ TI Modeling radiation- and carbon-use efficiencies of maize, sorghum, and rice SO AGRICULTURAL AND FOREST METEOROLOGY LA English DT Article DE photosynthesis; respiration; radiation-use efficiency; carbon-use efficiency; maize; sorghum; rice ID DRY-MATTER PRODUCTION; GRAIN-SORGHUM; LEAF PHOTOSYNTHESIS; NITROGEN; YIELD; RESPIRATION; AREA; CORN AB A previously developed model for radiation-use efficiency (RUE) for gross photosynthesis and net carbon accumulation by wheat before anthesis [Agric. Forest Meteorol. 101 (2000) 217], with some improvement. has been applied to maize, sorghum, and rice during their vegetative period under unstressed conditions. The objective of the present study is to assess the extent to which the model can provide RUE for net carbon accumulation and carbon-use efficiency (CUE; the ratio of daily net carbon accumulation and gross photosynthesis) for a range of incident irradiance and leaf area indices of maize, sorghum and rice, recognizing that (a) these crops are grown in substantially different environmental conditions than those for wheat, and (b) while rice is a C-3 crop like wheat, maize and sorghum are C-4 crops. The calculated RUE values for net carbon accumulation differed from observations (five for maize, two for sorghum and three for rice) by -24% to +19%, with an average (n = 10) of -4% (underestimation), while the calculated CUE values are found to be within the range of observations. The model parameters have not been calibrated or adjusted for these comparisons. Calculations suggest that there is much room to increase the RUE of sorghum over the currently available measurements, although it might not attain the potential maximum value for maize. The effects of variations in the maximum rate of leaf photosynthesis among cultivars, changes in the relationship between maximum rate of photosynthesis by leaves and its nitrogen content, and uncertainties in the input canopy parameters on RUE and CUE are assessed by sensitivity analysis. Published by Elsevier Science B.V. C1 NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. RP Choudhury, BJ (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. NR 28 TC 35 Z9 47 U1 0 U2 17 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 FEB 26 PY 2001 VL 106 IS 4 BP 317 EP 330 DI 10.1016/S0168-1923(00)00217-3 PG 14 WC Agronomy; Forestry; Meteorology & Atmospheric Sciences SC Agriculture; Forestry; Meteorology & Atmospheric Sciences GA 396FL UT WOS:000166625600005 ER PT J AU Anbar, AD Zahnle, KJ Arnold, GL Mojzsis, SJ AF Anbar, AD Zahnle, KJ Arnold, GL Mojzsis, SJ TI Extraterrestrial iridium, sediment accumulation and the habitability of the early Earth's surface SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ARCHEAN CRUSTAL EVOLUTION; CRETACEOUS-TERTIARY BOUNDARY; SOUTHERN WEST GREENLAND; BANDED IRON-FORMATION; IMPACT-MELT BRECCIAS; ITSAQ GNEISS COMPLEX; ACCRETION RATE; NATURAL-WATERS; INITIAL PB; ISOTOPE SYSTEMATICS AB We have measured the concentrations of iridium and platinum in ancient metasediments from Akilia Island, southern West Greenland, to obtain the first direct constraints on the extraterrestrial mass flux at the Earth's surface before 3.8 Gyr. The lunar impact record indicates this was a time of heavy bombardment; the average lunar cratering rate between 4.15 and 3.8 Gyr was elevated similar to 150 times the modern value. Hence, heightened Ir and Pt abundances are possible in sediments from this time. However, the observed concentrations of Ir and Pt in the Akilia metasediments are extremely low. In most samples, Ir <3 ppt and Pt <20 ppt. In contrast, the average modern crustal abundances of Ir and Pt are similar to 50 ppt and similar to2 ppb, respectively. The very low concentrations observed in the Akilia metasediments (cherts and banded iron formations) can be reconciled with the lunar record by quantifying the effects of sedimentation rate on the efficiency with which the extraterrestrial mass flux is sampled. The observations are explained if rapidly accumulating sediments sampled stochastic bombardment by an impactor population governed by a power law mass distribution, such that exogenous Ir and Pt are concentrated in rare horizons. The required sedimentation rates are geologically plausible. This explanation has two consequences. First, evidence of massive impact events may be rare in sediments older than 3.8 Gyr despite heavy bombardment. Second, conditions at the Earth's surface may have been conducive for extensive accumulation of sedimentary sequences and for microbial life during most of the period 4.15-3.8 Gyr. It is possible that the Earth's surface hosted microbial habitats during most of this time if microbes living in deep-sea or deep-crustal environments survived photic zone vaporizing impacts that would have occurred every similar to 30 Myr, Hence, evidence of life is expected even in the earliest sedimentary sequences. C1 Univ Rochester, Dept Earth & Environm Sci, Rochester, NY 14627 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Univ Calif Los Angeles, IGPP Ctr Astrobiol, Dept Earth & Space Sci, Los Angeles, CA USA. RP Univ Rochester, Dept Earth & Environm Sci, 601 Elmwood Ave, Rochester, NY 14627 USA. RI Arnold, Gail/A-5572-2010 NR 79 TC 33 Z9 33 U1 1 U2 4 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 FEB 25 PY 2001 VL 106 IS E2 BP 3219 EP 3236 DI 10.1029/2000JE001272 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 404TE UT WOS:000167116200001 ER PT J AU Shu, Y Li, BQ de Groh, HC AF Shu, Y Li, BQ de Groh, HC TI Numerical study of g-jitter induced double-diffusive convection SO NUMERICAL HEAT TRANSFER PART A-APPLICATIONS LA English DT Article ID STOCKBARGER CRYSTAL-GROWTH; LOW GRAVITY TOLERANCE; G-SENSITIVITY; ACCELERATIONS; SIMULATION AB A finite element study is presented of double-diffusive convection driven by g-jitter in a microgravity environment. Mathematical formulations are presented and extensive simulations are carried out for g-jitter induced fluid flow, temperature distribution, and solutal transport in an alloy system under consideration for space flights. Computations include the use of idealized single-frequency and multifrequency g-jitter as well as the real g-jitter data taken during an actual Space Shuttle flight. Little correlation is seen between these velocity components for the g-jitter components studied. The temperature field is basically undisturbed by convection because of a small Pr nnumber for the fluid. The disturbance of the concentration field, however, is pronounced, and the local variation of the concentration follows the velocity oscillation in time. It is found that although the concentration field varies in both position and time, the local concentration gradient remains approximately constant in time. Numerical study further indicates that with an increase in g-jitter force (or amplitude), the nonlinear convective effects become much more obvious, which in turn drastically change the concentration fields. The simulated, results computed using the g-jitter data taken during space flights show that both the velocity and concentration become random, following approximately the same pattern as the g-jitter perturbations. C1 Washington State Univ, Sch Mech & Mat Engn, Dept Mech Engn, Pullman, WA 99164 USA. NASA, Lewis Res Ctr, Cleveland, OH 44135 USA. RP Li, BQ (reprint author), Washington State Univ, Sch Mech & Mat Engn, Dept Mech Engn, POB 642920, Pullman, WA 99164 USA. EM li@mme.wsu.edu NR 16 TC 21 Z9 21 U1 0 U2 0 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 USA SN 1040-7782 J9 NUMER HEAT TR A-APPL JI Numer. Heat Tranf. A-Appl. PD FEB 23 PY 2001 VL 39 IS 3 BP 245 EP 265 PG 21 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA 406TK UT WOS:000167231100003 ER PT J AU Becker, L Poreda, RJ Hunt, AG Bunch, TE Rampino, M AF Becker, L Poreda, RJ Hunt, AG Bunch, TE Rampino, M TI Impact event at the Permian-Triassic boundary: Evidence from extraterrestrial noble gases in fullerenes SO SCIENCE LA English DT Article ID MASS EXTINCTION; CRETACEOUS-TERTIARY; SOUTHWEST JAPAN; BEDDED CHERT; SEDIMENT; HISTORY; HELIUM; SEARCH; HE-3 AB The Permian-Triassic boundary (PTB) event, which occurred about 251.4 million years ago, is marked by the most severe mass extinction in the geologic record. Recent studies of some PTB sites indicate that the extinctions occurred very abruptly, consistent with a catastrophic, possibly extraterrestrial, cause. Fullerenes (C-60 to C-200) from sediments at the PTB contain trapped helium and argon with isotope ratios similar to the planetary component of carbonaceous chondrites. These data imply that an impact event (asteroidal or cometary) accompanied the extinction, as was the case for the Cretaceous-Tertiary extinction event about 65 million years ago. C1 Univ Washington, Dept Earth & Space Sci, Seattle, WA 98195 USA. Univ Rochester, Dept Earth & Environm Sci, Rochester, NY 14627 USA. NASA, Ames Res Ctr, Div Space Sci, Moffett Field, CA 94035 USA. NYU, New York, NY 10003 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. RP Becker, L (reprint author), Univ Washington, Dept Earth & Space Sci, Box 351310, Seattle, WA 98195 USA. NR 38 TC 266 Z9 311 U1 10 U2 73 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 FEB 23 PY 2001 VL 291 IS 5508 BP 1530 EP 1533 DI 10.1126/science.1057243 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 405HF UT WOS:000167153400040 PM 11222855 ER PT J AU Tuthill, PG Monnier, JD Danchi, WC AF Tuthill, PG Monnier, JD Danchi, WC TI A dusty torus around the luminous young star LkH alpha 101 SO NATURE LA English DT Article ID HERBIG AE/BE STARS; INTERMEDIATE-MASS STARS; PROTOSTELLAR DISKS; INFRARED-EMISSION; STELLAR OBJECTS; PHOTOEVAPORATION AB A star forms when a cloud of dust and gas collapses. It is generally believed that this collapse first produces a flattened rotating disk(1,2), through which matter is fed onto the embryonic star at the centre of the disk. When the temperature and density at the centre of the star pass a critical threshold, thermonuclear fusion begins. The remaining disk, which can still contain up to 0.3 times the mass of the star(3-5), is then sculpted and eventually dissipated by the radiation and wind from the newborn star. But this picture of the structure and evolution of the disk remains speculative because of the lack of morphological data of sufficient resolution and uncertainties regarding the underlying physical processes. Here we present images of a young star, LkH alpha 101, in which the structure of the inner accretion disk is resolved. We rnd that the disk is almost face-on, with a central gap (or cavity) and a hot inner edge. The cavity is bigger than previous theoretical predictions(6), and we infer that the position of the inner edge is probably determined by sublimation of dust grains by direct stellar radiation, rather than by disk-reprocessing or viscous-heating processes as usually assumed(29). C1 Univ Sydney, Sch Phys, Dept Astron, Sydney, NSW 2006, Australia. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Tuthill, PG (reprint author), Univ Sydney, Sch Phys, Dept Astron, Sydney, NSW 2006, Australia. NR 29 TC 91 Z9 93 U1 0 U2 0 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 22 PY 2001 VL 409 IS 6823 BP 1012 EP 1014 DI 10.1038/35059014 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 405FT UT WOS:000167148800036 PM 11234003 ER PT J AU Rothschild, LJ Mancinelli, RL AF Rothschild, LJ Mancinelli, RL TI Life in extreme environments SO NATURE LA English DT Review ID LITORALIS DNA-POLYMERASE; DEEP-SEA MICROORGANISMS; COLI PLASMID PUC19; DEINOCOCCUS-RADIODURANS; DESICCATION TOLERANCE; MICROBIAL DIVERSITY; UVC RADIATION; VACUUM UV; BACTERIA; PRESSURE AB Each recent report of liquid water existing elsewhere in the Solar System has reverberated through the international press and excited the imagination of humankind. Why? Because in the past few decades we have come to realize that where there is liquid water on Earth, virtually no matter what the physical conditions, there is life. What we previously thought of as insurmountable physical and chemical barriers to life, we now see as yet another niche harbouring 'extremophiles'. This realization, coupled with new data on the survival of microbes in the space environment and modelling of the potential for transfer of life between celestial bodies, suggests that life could be more common than previously thought. Here we examine critically what it means to be an extremophile, and the implications of this for evolution, biotechnology and especially the search for life in the Universe. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Rothschild, LJ (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI Mancinelli, Rocco/L-8971-2016 NR 126 TC 660 Z9 723 U1 57 U2 474 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 22 PY 2001 VL 409 IS 6823 BP 1092 EP 1101 DI 10.1038/35059215 PG 10 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 405FT UT WOS:000167148800057 PM 11234023 ER PT J AU White, RJ Averner, M AF White, RJ Averner, M TI Humans in space SO NATURE LA English DT Article ID ORTHOSTATIC INTOLERANCE; SPACEFLIGHT AB Many successful space missions over the past 40 years have highlighted the advantages and necessity of humans in the exploration of space. But as space travel becomes ever more feasible in the twenty-first century, the health and safety of future space explorers will be paramount. In particular, understanding the risks posed by exposure to radiation and extended weightlessness will be crucial if humans are to travel far from Earth. C1 Natl Space Biomed Res Inst, Houston, TX 77030 USA. Baylor Coll Med, Houston, TX 77030 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP White, RJ (reprint author), Natl Space Biomed Res Inst, 1 Baylor Plaza,NA-425, Houston, TX 77030 USA. NR 36 TC 111 Z9 131 U1 9 U2 18 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 22 PY 2001 VL 409 IS 6823 BP 1115 EP 1118 DI 10.1038/35059243 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 405FT UT WOS:000167148800060 PM 11234026 ER PT J AU Hart, RC Balla, RJ Herring, GC AF Hart, RC Balla, RJ Herring, GC TI Simultaneous velocimetry and thermometry of air by use of nonresonant heterodyned laser-induced thermal acoustics SO APPLIED OPTICS LA English DT Article ID PRESSURE; GRATINGS; SPEED; SOUND AB Nonresonant laser-induced thermal acoustics is used with heterodyne detection to measure temperature (285-295 K) and a single component of velocity (20-150 m/s) in an atmospheric pressure, subsonic, unseeded air jet. Good agreement is found with Pitot-tube measurements of velocity (0.2% at 150 m/s and 2% at 20 m/s) and the isentropic expansion model for temperature (0.3%). OCIS codes: 120.7250, 280.7250. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hart, RC (reprint author), NASA, Langley Res Ctr, Mail Stop 493, Hampton, VA 23681 USA. EM g.c.herring@larc.nasa.gov NR 11 TC 13 Z9 13 U1 0 U2 3 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 FEB 20 PY 2001 VL 40 IS 6 BP 965 EP 968 DI 10.1364/AO.40.000965 PG 4 WC Optics SC Optics GA 400ZA UT WOS:000166901500030 PM 18357080 ER PT J AU Phillips, NG Kogut, A AF Phillips, NG Kogut, A TI Statistical power, the bispectrum, and the search for non-Gaussianity in the cosmic microwave background anisotropy SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations; methods : statistical ID COBE-DMR; SKY MAPS; INFLATIONARY UNIVERSE; GLOBAL TEXTURE; FLUCTUATIONS; TOPOLOGY; DENSITY; PERTURBATIONS AB We use simulated maps of the cosmic microwave background (CMB) anisotropy to quantify the ability of different statistical tests to discriminate between Gaussian and non-Gaussian models. Despite the central limit theorem on large angular scales, both the genus and extrema correlations are able to discriminate between Gaussian models and a semianalytic texture model selected as a physically motivated non-Gaussian model. When run on the COBE 4 year CMB maps, both tests prefer the Gaussian model. Although the bispectrum has comparable statistical power when computed on the full sky, once a Galactic cut is imposed on the data, the bispectrum loses the ability to discriminate between models. Off-diagonal elements of the bispectrum are comparable to the diagonal elements for the non-Gaussian texture model and must be included to obtain maximum statistical power. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Raytheon ITSS, Greenbelt, MD 20771 USA. RP Phillips, NG (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Raytheon ITSS, Code 685, Greenbelt, MD 20771 USA. NR 36 TC 29 Z9 29 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 FEB 20 PY 2001 VL 548 IS 2 BP 540 EP 549 DI 10.1086/319026 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 406FU UT WOS:000167204900004 ER PT J AU Sandford, SA Bernstein, MP Allamandola, LJ Goorvitch, D Teixeira, TCVS AF Sandford, SA Bernstein, MP Allamandola, LJ Goorvitch, D Teixeira, TCVS TI The abundances of solid N(2) and gaseous CO(2) in interstellar dense molecular clouds SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM : lines and bands; ISM : abundances; ISM : molecules; methods : laboratory; molecular data; techniques : spectroscopic ID INFRARED SPECTRAL PROPERTIES; TAURUS DARK CLOUD; GRAIN MANTLES; ICE ANALOGS; ISOTOPIC-SUBSTITUTION; MICRON ABSORPTION; GAS; SPECTROSCOPY; SURFACE; TRITON AB We present 2338-2322 cm(-1) (4.277-4.307 mum) infrared spectra of a number of mixed N(2)-containing molecular ices and demonstrate that the strength of the infrared "forbidden" band due to the N=N stretch near 2328 cm(-1) (4.295 mum) is extremely sensitive to the composition of the ice. The strength of the 2328 cm(-1) N(2) fundamental is significantly enhanced relative to that of pure N(2) ice when NH(3), H(2)O, or CO(2) are present, but it is largely unaffected by the presence of CO, CH(4), or O(2). We use the laboratory data in conjunction with Infrared Space Observatory (ISO) data that probe several lines of sight through dense molecular clouds to place limits on the abundance of interstellar solid phase N(2) and the composition of the ices. Deriving upper limits is complicated by the presence of overlapping absorptions due to CO(2) gas in the clouds and, in some cases, to photospheric CO in the background star. These upper limits are just beginning to be low enough to constrain interstellar grain models and the composition of possible N(2)-bearing interstellar ices. We outline the search criteria that will need to be met if solid interstellar N(2) is to be detected in the future. We also discuss some of the implications of the presence of warm CO(2) gas along the lines of sight to embedded protostars and demonstrate that its presence may help resolve certain puzzles associated with the previously derived gas/solid CO(2) ratios and the relative abundances of polar and nonpolar ices toward these objects. Finally, we briefly comment on the possible implications of these results for the interpretation of N(2) detections on outer solar system bodies. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. SETI Inst, Mountain View, CA 94043 USA. Univ Aarhus, Inst Phys & Astron, DK-8000 Aarhus C, Denmark. RP Sandford, SA (reprint author), NASA, Ames Res Ctr, Mail Stop 245-6, Moffett Field, CA 94035 USA. NR 48 TC 33 Z9 33 U1 0 U2 6 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 FEB 20 PY 2001 VL 548 IS 2 BP 836 EP 851 DI 10.1086/319023 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 406FU UT WOS:000167204900026 ER PT J AU Marsh, KA Bloemhof, EE Koerner, DW Ressler, ME AF Marsh, KA Bloemhof, EE Koerner, DW Ressler, ME TI Mid-infrared images of the circumstellar dust around alpha Scorpii SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; infrared : stars; stars : individual (alpha Scorpii); stars : late-type ID STARS; SUPERGIANT; VARIABLES; PERIODS; SHELLS AB We present the first two-dimensional mid-infrared images of the circumstellar dust distribution around the supergiant star alpha Scorpii. Our observations were made at wavelengths of 12.5 and 20.8 mum using the MIRLIN focal-plane array camera on the Keck II 10 m telescope, with spatial resolution (lambda /D) of 0."29 and 0."48 at the two wavelengths, respectively. Our deconvolved images, which provide a resolution enhancement of approximately a factor of 2, show that the dust shell previously detected in one-dimensional scans is actually highly nonuniform. Specifically, the shell is now seen to be concentrated largely into three discrete clumps, and there is evidence of a more recent ejection which has left a central concentration of dust within about 0."3 from the star. C1 CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Univ Penn, Philadelphia, PA 19103 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Marsh, KA (reprint author), CALTECH, Ctr Infrared Proc & Anal, 100-22, Pasadena, CA 91125 USA. NR 16 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 FEB 20 PY 2001 VL 548 IS 2 BP 861 EP 867 DI 10.1086/319035 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 406FU UT WOS:000167204900028 ER PT J AU Penny, LR Seyle, D Gies, DR Harvin, JA Bagnuolo, WG Thaller, ML Fullerton, AW Kaper, L AF Penny, LR Seyle, D Gies, DR Harvin, JA Bagnuolo, WG Thaller, ML Fullerton, AW Kaper, L TI Tomographic separation of composite spectra. VII. The physical properties of the massive triple system HD 135240 (delta Circini) SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : eclipsing; binaries : spectroscopic; stars : early-type; stars : fundamental parameters; stars : individual (HD 135240); ultraviolet : stars ID O-TYPE STARS; ULTRAVIOLET RADIAL-VELOCITIES; SPECTROSCOPIC BINARY ORBITS; ROTATIONAL VELOCITIES; STELLAR WINDS; DH CEPHEI; COMPONENTS; TEMPERATURES; PARAMETERS; MAJORIS AB We present the results of a radial velocity study of the massive, double-lined, O binary HD 135240 based primarily on UV spectroscopy from the International Ultraviolet Explorer. Cross-correlation methods indicate the presence of a third stationary spectral line component which indicates that the system is a triple consisting of a central 3.9 day close binary with a distant companion. We measured radial velocities from the cross-correlation functions after removal of the third component, and we combined these with velocities obtained from H alpha spectroscopy to reassess the orbital elements. We applied a Doppler tomography algorithm to reconstruct the individual UV spectra of all three stars, and we determine spectral classifications of O7 III-V, O9.5 V, and B0.5 V for the primary, secondary, and tertiary, respectively, using UV criteria defined by Penny, Gies, & Bagnuolo. We compare these reconstructed spectra to standard single-star spectra to find the UV flux ratios of the components (F-2/F-1 = 0.239 +/- 0.022, and F-3/F-1 = 0.179 +/- 0.021). Hipparcos photometry reveals that the central pair is an eclipsing binary, and we present the first model Dt of the light curve from which we derive an orbital inclination, i = 74 degrees +/- 3 degrees. This analysis indicates that neither star is currently experiencing Roche lobe overflow. We place the individual components in the theoretical H-R diagram, and we show that the masses derived from the combined spectroscopic and photometric analysis and (M-p/M. = 21.6 +/- 2.0 M-s/M. = 12.4 +/- 1.0) are significantly lower than those computed from evolutionary tracks for single stars. C1 Coll Charleston, Dept Phys & Astron, Charleston, SC 29424 USA. Georgia State Univ, Ctr High Angular Resolut Astron, Atlanta, GA 30303 USA. Georgia State Univ, Dept Phys & Astron, Atlanta, GA 30303 USA. CALTECH, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Jet Propuls Lab, Pasadena, CA 91125 USA. Univ Victoria, Dept Phys & Astron, Victoria, BC V8W 3P6, Canada. Univ Amsterdam, Sterrenkundig Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. RP Penny, LR (reprint author), Coll Charleston, Dept Phys & Astron, 66 George St, Charleston, SC 29424 USA. NR 42 TC 18 Z9 18 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 FEB 20 PY 2001 VL 548 IS 2 BP 889 EP 899 DI 10.1086/319031 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 406FU UT WOS:000167204900032 ER PT J AU Ueta, T Meixner, M Dayal, A Deutsch, LK Fazio, GG Hora, JL Hoffmann, WF AF Ueta, T Meixner, M Dayal, A Deutsch, LK Fazio, GG Hora, JL Hoffmann, WF TI Discovery of an extended dust emission around IRAS 18576+0341 (AFGL 2298) at 10.3 and 18.0 microns: A new luminous blue variable candidate? SO ASTROPHYSICAL JOURNAL LA English DT Article DE circumstellar matter; dust, extinction; infrared : stars; stars : individual (IRAS 18576+0341, AFGL 2298); stars : mass loss ID PROTOPLANETARY NEBULA CANDIDATES; ETA-CARINAE; PLANETARY-NEBULAE; CIRCUMSTELLAR ENVELOPES; MASER EMISSION; STARS; SPECTRA; SPECTROMETER; PHOTOMETRY; MORPHOLOGY AB We report the detection of extended mid-infrared emission from IRAS 18576+0341 (AFGL 2298). The object shows a dusty circumstellar shell that has diameter of greater than or similar to 7" at 10.3 and 18.0 mum. The dust nebula shows two emission peaks concentrically elongated and symmetrically oriented on the opposite sides of the third, central peak, which appears to be the central star of the system. The observed mid-infrared morphology indicates that the circumstellar dust shell has an equatorially enhanced material distribution, which is a common signature of stellar objects that have experienced mass loss. Radiative transfer model calculations suggest that the central star is an extremely bright star at a distance (L-* = 10(6.4) L .) of about 10 kpc: this object is best described as a new luminous blue variable candidate. The circumstellar dust shell seems to have been generated by an equatorially-enhanced mass loss process with (M) over dot greater than or equal to 6.8 x 10(-6) M. yr(-1) and (M) over dot (pole)/(M) over dot (eq) similar to 0.5. C1 Univ Illinois, Dept Astron, Urbana, IL 61801 USA. CALTECH, Jet Prop Lab, IPAC, Pasadena, CA 91125 USA. Boston Univ, Dept Astron, Boston, MA 02215 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. RP Ueta, T (reprint author), Univ Illinois, Dept Astron, MC-221, Urbana, IL 61801 USA. OI Hora, Joseph/0000-0002-5599-4650 NR 56 TC 23 Z9 23 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 FEB 20 PY 2001 VL 548 IS 2 BP 1020 EP 1028 DI 10.1086/319004 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 406FU UT WOS:000167204900042 ER PT J AU Ferrin, I Rabinowitz, D Schaefer, B Snyder, J Ellman, N Vicente, B Rengstorf, A Depoy, D Salim, S Andrews, P Bailyn, C Baltay, C Briceno, C Coppi, P Deng, M Emmet, W Oemler, A Sabbey, C Shin, J Sofia, S van Altena, W Vivas, K Abad, C Bongiovanni, A Bruzual, G Della Prugna, F Herrera, D Magris, G Mateu, J Pacheco, R Sanchez, G Sanchez, G Schenner, H Stock, J Vieira, K Fuenmayor, F Hernandez, J Naranjo, O Rosenzweig, P Secco, C Spavieri, G Gebhard, M Honeycutt, K Mufson, S Musser, J Pravdo, S Helin, E Lawrence, K AF Ferrin, I Rabinowitz, D Schaefer, B Snyder, J Ellman, N Vicente, B Rengstorf, A Depoy, D Salim, S Andrews, P Bailyn, C Baltay, C Briceno, C Coppi, P Deng, M Emmet, W Oemler, A Sabbey, C Shin, J Sofia, S van Altena, W Vivas, K Abad, C Bongiovanni, A Bruzual, G Della Prugna, F Herrera, D Magris, G Mateu, J Pacheco, R Sanchez, G Sanchez, G Schenner, H Stock, J Vieira, K Fuenmayor, F Hernandez, J Naranjo, O Rosenzweig, P Secco, C Spavieri, G Gebhard, M Honeycutt, K Mufson, S Musser, J Pravdo, S Helin, E Lawrence, K TI Discovery of the bright trans-Neptunian object 2000 EB(173) SO ASTROPHYSICAL JOURNAL LA English DT Article DE Kuiper Belt; minor planets, asteroids : individual (2000 EB(173)); surveys ID KUIPER-BELT OBJECTS; SLOW-MOVING OBJECTS; SOLAR-SYSTEM; CCD SURVEY; SEARCH; DIVERSITY; TELESCOPE; CENTAURS AB We describe the discovery circumstances and photometric properties of 2000 EB(173), now one of the brightest trans-Neptunian objects (TNOs) with opposition magnitude m(R) = 18.9 and also one of the largest Plutinos, found with the drift-scanning camera of the Quasar Equatorial Survey Team, attached to the 1 m Schmidt telescope of the National Observatory of Venezuela. We measure B-V = 0.99 +/- 0.14 and V-R = 0.57 +/- 0.05, a red color observed for many fainter TNOs. At our magnitude limit m(R) = 20.1 +/- 0.20, our single detection reveals a sky density of 0.915(-0.012)(+0.034) TNOs per square degree (the error bars are 68% confidence limits), consistent with fainter surveys showing a cumulative number proportional to 10(0.5mR). Assuming an inclination distribution of TNOs with FWHM exceeding 30 degrees, it is likely that 100 to several hundred objects brighter than m(R) = 20.1 remain to be discovered. C1 Univ Los Andes, Dept Fis, Merida 5101, Venezuela. Yale Univ, Dept Phys, New Haven, CT 06520 USA. Yale Univ, Dept Astron, New Haven, CT 06520 USA. Ctr Invest Astron, Merida 5101A, Venezuela. Univ Zaragoza, Grp Mecan Espacial, E-50009 Zaragoza, Spain. Indiana Univ, Dept Astron, Bloomington, IN 47405 USA. Ohio State Univ, Dept Astron, Columbus, OH 43210 USA. Carnegie Observ, Pasadena, CA 91101 USA. Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Ferrin, I (reprint author), Univ Los Andes, Dept Fis, Merida 5101, Venezuela. EM ferrin@ciens.ula.ve RI Bongiovanni, Angel/J-6176-2012 NR 31 TC 14 Z9 15 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 FEB 20 PY 2001 VL 548 IS 2 BP L243 EP L247 DI 10.1086/319109 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 406HD UT WOS:000167208100030 ER PT J AU Kuntz, KD Snowden, SL Mushotzky, RF AF Kuntz, KD Snowden, SL Mushotzky, RF TI X-ray constraints on the warm-hot intergalactic medium SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; diffuse radiation; X rays : ISM ID BACKGROUND SPECTRUM AB Three observational constraints can be placed on a warm-hot intergalactic medium (WHIM) using ROSAT Position Sensitive Proportional Counter pointed observations and survey data: the emission strength, the energy spectrum, and the fluctuation spectrum. The upper limit to the emission strength of the WHIM is keV 7.5 +/- 1.0 s(-1) cm(-2) sr(-1) keV(-1) in the 3/4 keV band, an unknown portion of which value may be due to our own Galactic halo. The spectral shape of the WHIM emission can be described as thermal emission with, although log T = 6.42 the true spectrum is more likely to come from a range of temperatures. The values of the emission strength and spectral shape are in reasonable agreement with hydrodynamical cosmological models. The autocorrelation function in the 0.44 keV < E < 1.21 keV band range, w(theta) for the extragalactic soft X-ray background (SXRB), which includes both the WHIM and the contributions due to point sources, is less than or similar to0.002 for in the 10' < < 20' in the 3/4 keV band. This value is lower than the Croft et al. cosmological model by a factor of 5 but is still not inconsistent with cosmological models. It is also found that the normalization of the extragalactic power-law component of the SXRB spectrum must be 9.5 +/- 0.0 keV s(-1) cm(-2) sr(-1) keV(-1) to be consistent with the ROSAT All-Sky Survey. 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. RI Snowden, Steven/D-5292-2012 NR 25 TC 33 Z9 33 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 FEB 20 PY 2001 VL 548 IS 2 BP L119 EP L122 DI 10.1086/319117 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 406HD UT WOS:000167208100003 ER PT J AU Reames, DV Ng, CK Tylka, AJ AF Reames, DV Ng, CK Tylka, AJ TI Heavy ion abundances and spectra and the large gradual solar energetic particle event of 2000 July 14 SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; shock waves; Sun : abundances; Sun : corona; Sun : particle emission ID TEMPORAL EVOLUTION; ACCELERATION; TRANSPORT; SHOCKS; WAVES AB We compare the spectra and abundances of heavy elements of atomic number Z in the range with 34 less than or equal to Z less than or equal to 40 those of He, C, O, Ne, Si, and Fe, as observed on the Wind spacecraft, in the large solar energetic particle (SEP) events of 1998 April 20 and 2000 July 14. This is the first time that spectra of the rare, trans-Fe, 34 less than or equal to Z less than or equal to 40 ions have been measured in SEP events. We use the systematic dependence of the spectral e-folding energies on the charge-to-mass ratio (Q/A) of the species to estimate ionization states of each species. Ionization states of Q similar to 11 for ions with 34 less than or equal to Z less than or equal to 40 are comparable to those for Si and Fe. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Reames, DV (reprint author), NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. RI Tylka, Allan/G-9592-2014 NR 19 TC 26 Z9 27 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 FEB 20 PY 2001 VL 548 IS 2 BP L233 EP L236 DI 10.1086/319100 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 406HD UT WOS:000167208100028 ER PT J AU Sulkanen, ME Bregman, JN AF Sulkanen, ME Bregman, JN TI Are there advection-dominated accretion flows in nearby giant elliptical galaxies? SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : elliptical and lenticular, cD; X rays : galaxies ID X-RAY-EMISSION; COOLING FLOWS; CONSTRAINTS; CORES AB Recently, it has been suggested that the hard X-ray power-law tails exhibited in the ASCA spectra of several nearby giant elliptical galaxies are caused by low radiative efficiency accretion flows (advection-dominated accretion flows [ADAFs]) onto a massive black hole in the centers of the galaxies. The estimated fluxes from these central ADAFs as derived from the ASCA X-ray spectral analyses indicate that they may be visible as X-ray point sources. We analyze archival ROSAT HRI images of three such galaxies, NGC 1399, 4636, and 4696, to determine whether X-ray point sources consistent with ASCA-derived fluxes are present in the centers of the galaxies. We find that the upper limit for the flux of a central X-ray point source in each of these galaxies, as determined by the ROSAT HRI data, is only marginally consistent with the predicted flux inferred from the ASCA spectra. We suggest that although a central point source, such as an ADAF associated with a massive black hole, cannot be completely ruled out, they can only account for a fraction of the flux of the observed hard X-ray power-law components. C1 Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Xray Astron Grp, Huntsville, AL 35812 USA. RP Sulkanen, ME (reprint author), Univ Michigan, Dept Astron, 830 Dennison,501 E Univ Ave, Ann Arbor, MI 48109 USA. NR 21 TC 6 Z9 6 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 2001 VL 548 IS 2 BP L131 EP L134 DI 10.1086/319089 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 406HD UT WOS:000167208100006 ER PT J AU Shaheen, PA Stehlik, LL Meise, CJ Stoner, AW Manderson, JP Adams, DL AF Shaheen, PA Stehlik, LL Meise, CJ Stoner, AW Manderson, JP Adams, DL TI Feeding behavior of newly settled winter flounder (Pseudopleuronectes americanus) on calanoid copepods SO JOURNAL OF EXPERIMENTAL MARINE BIOLOGY AND ECOLOGY LA English DT Article DE Acartia hudsonica; Eurytemora affinis; Pseudopleuronectes americanus; selective predation ID EURYTEMORA-AFFINIS; VERTICAL MIGRATION; PLANKTONIC COPEPOD; PREY SELECTION; COASTAL AREA; LARVAL FISH; BALTIC SEA; ZOOPLANKTON; ESTUARY; PREDATION AB Field and laboratory investigations were conducted to examine feeding by newly settled winter flounder (Pseudopleuronectes americanus) on two co-occurring calanoid copepods, Eurytemora affinis and Acartia hudsonica. During the spring, these prey are present when winter flounder initiate their demersal lifestyle in estuaries of the northeastern United States. Epibenthic zooplankton were collected concurrently with winter flounder in the Navesink River estuary, NJ, in May 1998 and 1999. Although both calanoid species were in the estuary during the 2-year survey, E. affinis was consumed nearly to the exclusion of A. hudsonica by newly settled winter flounder. Annually, E. affinis and A. hudsonica had similar size distributions in field collections, indicating that species choice was not size selective. However, when preying on E. affinis, winter flounder preferred the larger sized organisms. In single species laboratory experiments, E. affinis and A. hudsonica were consumed equally by newly settled winter flounder (19-23 mm TL), but there were more strikes made toward E. affinis. Despite the lower catch efficiency, E. affinis was selected over A. hudsonica when the prey species were offered together in equal numbers. The selection for E. affinis over A. hudsonica by newly settled winter flounder may be the result of behavioral and/or morphological differences in the prey species. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Rutgers State Univ, Inst Marine & Coastal Sci, New Brunswick, NJ 08903 USA. Natl Marine Fisheries Serv, US Dept Commerce, NOAA,NE Fisheries Sci Ctr, James J Howard Marine Sci Lab, Highlands, NJ 07732 USA. Natl Marine Fisheries Serv, Fisheries Behav Ecol Program, Alaska Fisheries Sci Ctr, Newport, OR 97365 USA. RP Shaheen, PA (reprint author), Rutgers State Univ, Inst Marine & Coastal Sci, New Brunswick, NJ 08903 USA. NR 48 TC 10 Z9 10 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0981 J9 J EXP MAR BIOL ECOL JI J. Exp. Mar. Biol. Ecol. PD FEB 20 PY 2001 VL 257 IS 1 BP 37 EP 51 DI 10.1016/S0022-0981(00)00335-X PG 15 WC Ecology; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA 402XP UT WOS:000167013700003 ER PT J AU Feldman, HA Frieman, JA Fry, JN Scoccimarro, R AF Feldman, HA Frieman, JA Fry, JN Scoccimarro, R TI Constraints on galaxy bias, matter density, and primordial non-Gaussianity from the PSCz galaxy redshift survey SO PHYSICAL REVIEW LETTERS LA English DT Article ID LARGE-SCALE BIAS; POWER-SPECTRUM; BISPECTRUM; DISTORTIONS; SPACE; EVOLUTION; UNIVERSE; CATALOG; OMEGA AB We compute the bispectrum fur the IRAS PSCz catalog and find that the galaxy distribution displays the characteristic signature of gravity. Assuming Gaussian initial conditions, we obtain galaxy biasing parameters 1/b(1) = 1.20(-0.19)(+0.18) and b(2)/b(1)(2) = -0.42 +/- 0.19, with no sign of scale-dependent bias for k less than or equal to 0.3h Mpc(-1). These results impose stringent constraints on non-Gaussian initial conditions. For dimensional scaling models with chi (2)(N) statistics, we find N > 49, which implies a constraint on primordial skewness B-3 < 0.35. C1 Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA. NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. Univ Florida, Dept Phys, Gainesville, FL 32611 USA. Inst Adv Study, Sch Nat Sci, Princeton, NJ 08540 USA. RP Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA. EM feldman@ukans.edu; frieman@fnal.gov; fry@phys.ufl.edu; scoccima@ias.edu NR 33 TC 76 Z9 76 U1 0 U2 1 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 FEB 19 PY 2001 VL 86 IS 8 BP 1434 EP 1437 DI 10.1103/PhysRevLett.86.1434 PG 4 WC Physics, Multidisciplinary SC Physics GA 402VZ UT WOS:000167010000010 PM 11290161 ER PT J AU Goodwin, TJ AF Goodwin, TJ TI The Scientist connection SO SCIENTIST LA English DT Letter C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Goodwin, TJ (reprint author), NASA, Lyndon B Johnson Space Ctr, 2101 NASA Rd 1, Houston, TX 77058 USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU SCIENTIST INC PI PHILADELPHIA PA 3600 MARKET ST SUITE 450, PHILADELPHIA, PA 19104 USA SN 0890-3670 J9 SCIENTIST JI Scientist PD FEB 19 PY 2001 VL 15 IS 4 BP 6 EP 6 PG 1 WC Information Science & Library Science; Multidisciplinary Sciences SC Information Science & Library Science; Science & Technology - Other Topics GA 424RV UT WOS:000168246000005 ER PT J AU Beyerle, G Deckelmann, H Neuber, R Rosen, JM Reimer, E Scheoberl, MR AF Beyerle, G Deckelmann, H Neuber, R Rosen, JM Reimer, E Scheoberl, MR TI Occurrence of solid particles in the winter polar stratosphere above the nitric acid trihydrate coexistence temperature inferred from ground-based polarization lidar observations at Ny-Alesund, Spitsbergen SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID T-MATRIX COMPUTATIONS; ARCTIC STRATOSPHERE; LIGHT-SCATTERING; OZONE LOSS; CLOUDS; AEROSOLS; DENITRIFICATION; CHEMISTRY; DROPLETS; VORTEX AB Depolarization data of stratospheric aerosols obtained by ground-based polarization lidar are analyzed. The measurements were performed at Koldewey station, Ny-Angstrom lesund, Spitsbergen (78.9 degreesN, 11.9 degreesE), during the five winters of 1994-1995 to 1998-1999. The study is focused on stratospheric sulfuric acid aerosols; interference by nitric acid trihydrate containing particles is excluded by imposing a temperature threshold condition of 2 K above the nitric acid trihydrate coexistence temperature. Under the assumption that large sulfuric acid particles freeze first, T-matrix scattering calculations show that volume depolarizations start to increase significantly if similar to1% Of the aerosols are frozen. Observations in January 1999 and February 1998 indicate the presence of nonspherical particles. We interpret these observations as signatures for the occurrence of sulfuric acid tetrahydrate particles. Temperature histories obtained from back trajectory model calculations and the corresponding polarization lidar measurements are consistent with current knowledge of sulfuric acid tetrahydrate formation. C1 Alfred Wegener Inst Polar & Marine Res, Res Dept Potsdam, D-14473 Potsdam, Germany. Free Univ Berlin, Inst Meteorol, D-12165 Berlin, Germany. Univ Wyoming, Dept Phys & Astron, Laramie, WY 82071 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Beyerle, G (reprint author), Geoforschungszentrum Potsdam, Div Kinemat & Dynam Earth, D-14473 Potsdam, Germany. RI Neuber, Roland/B-4923-2014; OI Neuber, Roland/0000-0001-7382-7832; Beyerle, Georg/0000-0003-1215-2418 NR 46 TC 7 Z9 7 U1 0 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 FEB 16 PY 2001 VL 106 IS D3 BP 2979 EP 2992 DI 10.1029/2000JD900569 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 401TW UT WOS:000166945200008 ER PT J AU Stothers, RB AF Stothers, RB TI Major optical depth perturbations to the stratosphere from volcanic eruptions: Stellar extinction period, 1961-1978 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Review ID ATMOSPHERIC TRANSMISSION; ICE-SHEET; AEROSOL; SULFUR; SATELLITE; TURBIDITY; CLOUDS; LIDAR; BALI AB A revised chronology of stratospheric aerosol extinction due to volcanic eruptions has been assembled for the period 1961-1978, which immediately precedes the era of dedicated satellite measurements. On the whole, the most accurate data consist of published observations of stellar extinction, supplemented in part by other kinds of observational data. The period covered encompasses the important eruptions of Agung (1963) and Fuego (1974), whose dust veils are discussed with respect to their transport, decay, and total mass. The effective (area-weighted mean) radii of the aerosols for both eruptions are found to be 0.3-0.4 mum. It is confirmed that, among known tropical eruptions, Agung's dust was unique for a low-latitude eruption in remaining almost entirely confined to the hemisphere of its production. A new table of homogeneous visual optical depth perturbations, listed by year and by hemisphere, is provided for the whole period 1881-1978, including the pyrheliometric period before 1961 that was investigated previously. C1 NASA, Goddard Space Flight Ctr, Inst Space Studies, New York, NY 10025 USA. RP NASA, Goddard Space Flight Ctr, Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM rstothers@giss.nasa.gov NR 132 TC 21 Z9 22 U1 1 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 16 PY 2001 VL 106 IS D3 BP 2993 EP 3003 DI 10.1029/2000JD900652 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 401TW UT WOS:000166945200009 ER PT J AU Wu, J Dessler, AE AF Wu, J Dessler, AE TI Comparisons between measurements and models of Antarctic ozone loss SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID IN-SITU MEASUREMENTS; ARCTIC POLAR VORTEX; CHEMICAL LOSS; WINTER; DEPLETION; STRATOSPHERE; CLO; BRO; CHEMISTRY; RATES AB We present estimates of the chemical loss of lower stratospheric polar ozone during the Antarctic late winter directly from UARS Microwave Limb Sounder (MILS) ozone measurements in 1992, 1993, and 1994. These agree to within a few percent with estimates of the chemical loss inferred from UARS MLS ClO measurements. Thus, our results support the current theories of polar O-3-depleting chemistry, and we find no evidence far significant unknown chemistry during this period. C1 Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wu, J (reprint author), Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, 2207 Comp & Space Sci Bldg, College Pk, MD 20742 USA. RI Dessler, Andrew/G-8852-2012 OI Dessler, Andrew/0000-0003-3939-4820 NR 36 TC 13 Z9 13 U1 0 U2 2 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 FEB 16 PY 2001 VL 106 IS D3 BP 3195 EP 3201 DI 10.1029/2000JD900606 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 401TW UT WOS:000166945200025 ER PT J AU Nordeen, ML Minnis, P Doelling, DR Pethick, D Nguyen, L AF Nordeen, ML Minnis, P Doelling, DR Pethick, D Nguyen, L TI Satellite observations of cloud plumes generated by Nauru SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB A cloud plume is generated by the interaction of low-level easterly flow and diurnal surface heating on the island of Nauru in the tropical Pacific. Diurnal and seasonal cycles of cloud plume length, frequency, and heading were obtained by inspection of a year of hourly daytime GMS images. The cloud plume extends downwind and typically grows during the day to a mean length of 125 km by late afternoon with a maximum observed length of 425 km. The longest average plumes occur during March and April. The afternoon plume frequency was 63% compared to 50% for all observations. Further evaluation of the plume effects is needed to fully assess their impact on the development of long-term statistics of cloud and radiation parameters derived from surface instruments on the island's leeward side. C1 Analyt Serv & Mat Inc, Hampton, VA USA. NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Nordeen, ML (reprint author), Analyt Serv & Mat Inc, Hampton, VA USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 1 TC 15 Z9 15 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 FEB 15 PY 2001 VL 28 IS 4 BP 631 EP 634 DI 10.1029/2000GL012409 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 401MX UT WOS:000166916500019 ER PT J AU Paranicas, C Carlson, RW Johnson, RE AF Paranicas, C Carlson, RW Johnson, RE TI Electron bombardment of Europa SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INFRARED MAPPING SPECTROMETER; MAGNETOSPHERE; SURFACE; DISTRIBUTIONS; SATELLITES; GALILEO; IO AB Energetic electrons trapped in Jupiter's magnetic field are a principal source of energy for driving chemistry on the surface of Europa. Here we show that energetic (10 keV-10 MeV) electrons precipitate primarily on the trailing hemisphere, and we give the spatial distribution of the dose-rate deposited in Europa's surface. Based on this we propose that energetic electrons are a primary agent in determining the hemispherical differences in Europa's albedo, which have been attributed to differences in the incident ion flux. We compare the spatial distribution in the dose-rate deposited by the energetic electrons to the spatial distribution in the hydrate (likely frozen, hydrated sulfuric acid) determined by Galileo's near-infrared mapping spectrometer. This comparison supports the idea that radiolysis by the energetic electrons contributes significantly to producing the hydrate. C1 Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Virginia, Charlottesville, VA 22903 USA. RP Paranicas, C (reprint author), Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA. RI Paranicas, Christopher/B-1470-2016 OI Paranicas, Christopher/0000-0002-4391-8255 NR 19 TC 55 Z9 55 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 FEB 15 PY 2001 VL 28 IS 4 BP 673 EP 676 DI 10.1029/2000GL012320 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 401MX UT WOS:000166916500030 ER PT J AU Jones, NB Rinsland, CP Liley, JB Rosen, J AF Jones, NB Rinsland, CP Liley, JB Rosen, J TI Correlation of aerosol and carbon monoxide at 45 degrees S: Evidence of biomass burning emissions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Altitude profiles of Carbon Monoxide (CO) and aerosols have been compared from the Network for Stratospheric Change (NDSC) mid-latitude southern hemisphere site at Lauder, New Zealand. The CO mixing ratio profile was derived from infrared spectra recorded with a very high resolution Fourier Transform interferometer using three lines of the (1-0) band between 2057 and 2160 cm(-1). The aerosol surface area was derived from balloon-borne backscatter radiation at 940 nm. Both datasets show significant enhancements occurring over the observation site in the austral spring;. When displayed together their combined effect illustrates the close correlation between CO and aerosols. Peak concentrations are consistently recorded between September and October over a five year time frame (1994-1999), with the enhancements typically occurring at heights of between 3 to 8 km. The temporal and spatial correlation between the aerosol plumes and enhanced CO concentrations are interpreted in terms of the effect of long range transport of biomass burning: plumes in combination with the: Fl Nine-Southern Oscillation (ENSO) cycles influence on southern hemisphere climate dynamics. C1 Natl Inst Water & Autmospher Res, NIWA Lauder, Omakau, Central Otago, New Zealand. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23665 USA. Univ Wyoming, Dept Phys, Laramie, WY 82071 USA. RP Jones, NB (reprint author), Natl Inst Water & Autmospher Res, NIWA Lauder, Omakau, Central Otago, New Zealand. RI Jones, Nicholas/G-5575-2011 OI Jones, Nicholas/0000-0002-0111-2368 NR 15 TC 19 Z9 19 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 2001 VL 28 IS 4 BP 709 EP 712 DI 10.1029/2000GL012203 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 401MX UT WOS:000166916500039 ER PT J AU Aquino, AJA Taylor, PR Walch, SP AF Aquino, AJA Taylor, PR Walch, SP TI Structure, properties, and photodissociation of O-4(-) SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID DISSOCIATIVE PHOTODETACHMENT; BASIS-SETS; SPECTRUM; ATOMS; COINCIDENCE; MATRIX; ENERGY; ARGON AB We present the results of an ab initio quantum-chemical investigation of the structure of the anion O-4(-) and potential energy surfaces for several electronic states. In addition to ground-state vibrational frequencies, which are in good agreement with other calculations and with matrix isolation experiments, we have investigated both photodissociation of O-4(-) into various states of O-2 and O-2(-) and dissociative photodetachment leading to a free electron and various states of two O-2 molecules. Our surfaces lead to predictions for both photodissociation and photodetachment processes that are in excellent agreement with experiment. (C) 2001 American Institute of Physics. C1 Univ Calif San Diego, San Diego Supercomp Ctr, La Jolla, CA 92093 USA. Univ Calif San Diego, Dept Chem & Biochem, La Jolla, CA 92093 USA. NASA, Ames Res Ctr, Thermosci Inst, Moffett Field, CA 94035 USA. RP Aquino, AJA (reprint author), Univ Calif San Diego, San Diego Supercomp Ctr, MC 0505, La Jolla, CA 92093 USA. RI Aquino, Adelia/F-3226-2016 NR 15 TC 21 Z9 21 U1 0 U2 1 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD FEB 15 PY 2001 VL 114 IS 7 BP 3010 EP 3017 DI 10.1063/1.1288379 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 397TH UT WOS:000166713100022 ER PT J AU Gregg, WW Conkright, ME AF Gregg, WW Conkright, ME TI Global seasonal climatologies of ocean chlorophyll: Blending in situ and satellite data for the Coastal Zone Color Scanner era SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SOUTHERN-OCEAN; ATLANTIC-OCEAN; SEA; PHYTOPLANKTON; RADIANCE; BLOOMS; SHIP; COCCOLITHOPHORES; CALIBRATION; ALGORITHMS AB The historical archives of in situ (National Oceanographic Data Center) and satellite (Coastal Zone Color Scanner (CZCS)) chlorophyll data were combined using the blended analysis method of Reynolds [1988] in an attempt to construct an improved climatological seasonal representation of global chlorophyll distributions. The results of the blended analysis differed dramatically from the CZCS representation: Global chlorophyll estimates increased 8-35% in the blended analysis depending upon season. Regional differences were even larger, up to 140% in the equatorial Indian Ocean in summer (during the southwest monsoon). Tropical Pacific chlorophyll values increased 25-41%. The results suggested that the CZCS generally underestimates chlorophyll. Regional and seasonal differences in the blended analysis were sufficiently large as to produce a different representation of global chlorophyll distributions than otherwise inferred from CZCS data alone. Analyses of primary production and biogeochemical cycles may be substantially impacted by these results. C1 NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. NOAA, Natl Oceanog Data Ctr, Ocean Climate Lab, Silver Spring, MD 20910 USA. RP Gregg, WW (reprint author), NASA, Goddard Space Flight Ctr, Lab Hydrospher Proc, Greenbelt, MD 20771 USA. NR 39 TC 47 Z9 49 U1 1 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD FEB 15 PY 2001 VL 106 IS C2 BP 2499 EP 2515 DI 10.1029/1999JC000028 PG 17 WC Oceanography SC Oceanography GA 401AN UT WOS:000166904900011 ER PT J AU Blass, WE Jennings, L Ewing, AC Daunt, SJ Weber, MC Senesac, L Hager, S Hillman, JJ Reuter, DC Sirota, JM AF Blass, WE Jennings, L Ewing, AC Daunt, SJ Weber, MC Senesac, L Hager, S Hillman, JJ Reuter, DC Sirota, JM TI Absolute intensities in the nu(7) band of ethylene: tunable measurements used to calibrate FTS broadband spectra SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID LINES AB Three independent measurements of v(7) ethylene transitions at two different laboratories yield direct determinations of absolute intensity for 13 transitions. The 13 intensities are used to calibrate the intensities of a broadband high-resolution 10 mum spectrum of ethylene taken at the McMath Solar Telescope FTS facility. The least-squares fitting of the FTS intensity observations to the precisely determined TDL intensities results in validation of the broadband data for which sample pressure and temperature were marginally known. This "calibration" of the FTS spectrum makes it possible to determine intensities of transitions in several bands in the 800-1100 cm(-1) broadband FTS spectrum. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Univ Tennessee, Dept Phys & Astron, Mol Syst Lab, Knoxville, TN 37996 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. RP Blass, WE (reprint author), Univ Tennessee, Dept Phys & Astron, Mol Syst Lab, Knoxville, TN 37996 USA. RI Blass, William/A-2792-2008 NR 21 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 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD FEB 15 PY 2001 VL 68 IS 4 BP 467 EP 472 DI 10.1016/S0022-4073(00)00050-9 PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 390ED UT WOS:000166282000008 ER PT J AU Lange, AE Ade, PAR Bock, JJ Bond, JR Borrill, J Boscaleri, A Coble, K Crill, BP de Bernardis, P Farese, P Ferreira, P Ganga, K Giacometti, M Hivon, E Hristov, VV Iacoangeli, A Jaffe, AH Martinis, L Masi, S Mauskopf, PD Melchiorri, A Montroy, T Netterfield, CB Pascale, E Piacentini, F Pogosyan, D Prunet, S Rao, S Romeo, G Ruhl, JE Scaramuzzi, F Sforna, D AF Lange, AE Ade, PAR Bock, JJ Bond, JR Borrill, J Boscaleri, A Coble, K Crill, BP de Bernardis, P Farese, P Ferreira, P Ganga, K Giacometti, M Hivon, E Hristov, VV Iacoangeli, A Jaffe, AH Martinis, L Masi, S Mauskopf, PD Melchiorri, A Montroy, T Netterfield, CB Pascale, E Piacentini, F Pogosyan, D Prunet, S Rao, S Romeo, G Ruhl, JE Scaramuzzi, F Sforna, D TI Cosmological parameters from the first results of boomerang SO PHYSICAL REVIEW D LA English DT Article ID ANGULAR POWER SPECTRUM; MICROWAVE BACKGROUND ANISOTROPIES; AMERICAN TEST FLIGHT; DARK-MATTER; HUBBLE CONSTANT; RADIATION; UNIVERSE; CONSTRAINTS; SUPERNOVAE; DEFECTS AB The anisotropy of the cosmic microwave background radiation contains information about the contents and history of the universe. We report new limits on cosmological parameters derived from the angular power spectrum measured in the first Antarctic flight of the Boomerang experiment. Within the framework of models with adiabatic perturbations, and using only weakly restrictive prior probabilities on the age of the universe and the nubble expansion parameter h, we find that the curvature is consistent with Rat and that the primordial fluctuation spectrum is consistent with scale invariant, in agreement with the basic inflation paradigm. We find that the data prefer a baryon density Omega (b)h(2) above, though similar to, the estimates from light element abundances and big bang nucleosynthesis. When combined with large scale structure observations, the Boomerang data provide clear detections of both dark matter and dark energy contributions to the total energy density Omega (tot), independent of data from high-redshift supernovae. C1 CALTECH, Pasadena, CA 91125 USA. Queen Mary Univ London, London E1 4NS, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Toronto, Canadian Inst Theoret Astrophys, Toronto, ON, Canada. Univ Calif Berkeley, Lawrence Berkeley Lab, Natl Energy Res Sci Comp Ctr, Berkeley, CA 94720 USA. CNR, Ist Ric Onde Elettromagnet, I-50127 Florence, Italy. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy. Univ Oxford, Nucl & Astrophys Lab, Oxford OX2 6HT, England. Univ Geneva, Dept Phys Theor, CH-1211 Geneva 4, Switzerland. Coll France, F-75231 Paris 05, France. Univ Calif Berkeley, Ctr Particle Astrophys, Berkeley, CA 94720 USA. Ctr Ric Franscati, Comitato Nazl Ric & Sviluppo Energia Nucl & Energ, I-00044 Frascati, Italy. Univ Massachusetts, Dept Phys & Astron, Amherst, MA 01003 USA. Univ Toronto, Dept Phys, Toronto, ON, Canada. Univ Toronto, Dept Astron, Toronto, ON, Canada. Ist Nazl Geofis, I-00161 Rome, Italy. RP CALTECH, Pasadena, CA 91125 USA. RI Jaffe, Andrew/D-3526-2009; Piacentini, Francesco/E-7234-2010 OI Piacentini, Francesco/0000-0002-5444-9327 NR 30 TC 276 Z9 277 U1 1 U2 4 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2470-0010 EI 2470-0029 J9 PHYS REV D JI Phys. Rev. D PD FEB 15 PY 2001 VL 63 IS 4 AR 042001 DI 10.1103/PhysRevD.63.042001 PG 8 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 402PG UT WOS:000166996900005 ER PT J AU Teplitz, HI Hill, RS Malumuth, EM Collins, NR Gardner, JP Palunas, P Woodgate, BE AF Teplitz, HI Hill, RS Malumuth, EM Collins, NR Gardner, JP Palunas, P Woodgate, BE TI Wide-field imaging of the Hubble Deep Field-South region. II. The evolution of galaxy clustering at z < 1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : clusters : general; galaxies : evolution ID HIGH-REDSHIFT GALAXIES; STAR-FORMING GALAXIES; ANGULAR-CORRELATION FUNCTION; 2-POINT CORRELATION-FUNCTION; MORPHOLOGICAL SEGREGATION; PHOTOMETRIC REDSHIFTS; POWER SPECTRUM; SELECTION; STATISTICS; CATALOGS AB We present the galaxy-galaxy angular correlations as a function of photometric redshift in a deep, wide galaxy survey centered on the Hubble Deep Field-South (HDF-S). Images were obtained with the Big Throughput Camera on the Blanco 4 m telescope at CTIO, of 1/2 square degree in broadband uBV RI, reaching similar to 24 mag. Approximately 40,000 galaxies are detected in the survey. We determine photometric redshifts using galaxy template fitting to the photometry. Monte Carlo simulations show that redshifts from these data should be reliable out to z similar to 1, where the 4000 Angstrom shifts into the I band. The inferred redshift distribution, n(z), shows good agreement with the distribution of galaxies measured in the Hubble Deep Field-North (HDF-N) and the Canada-France Redshift Survey. After assigning galaxies to redshift bins with width Deltaz = 0.33, we determine the two-point angular correlation function in each bin. We find that the amplitude of the correlation A(w), drops across the three bins to redshift z similar to 1. Simple epsilon models of clustering evolution fit this result, with the best agreement for epsilon = 0. Hierarchical cold dark matter models best fit in a low-density, Lambda -dominated universe. C1 NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. EM hit@binary.gsfc.nasa.gov RI Woodgate, Bruce/D-2970-2012 NR 73 TC 19 Z9 19 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 FEB 10 PY 2001 VL 548 IS 1 BP 127 EP 140 DI 10.1086/318664 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QN UT WOS:000166939900011 ER PT J AU Dupke, RA Arnaud, KA AF Dupke, RA Arnaud, KA TI Central elemental abundance ratios in the Perseus Cluster: Resonant scattering or SN Ia enrichment? SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : abundances; galaxies : clusters : individual (Perseus); supernovae : general; X-rays : galaxies ID X-RAY OBSERVATIONS; INTRACLUSTER MEDIUM ENRICHMENT; IRON ABUNDANCES; METAL ABUNDANCE; GALAXIES AWM-7; II SUPERNOVAE; EMITTING GAS; ASCA; SPECTRA; TEMPERATURE AB We have determined abundance ratios in the core of the Perseus Cluster for several elements. These ratios indicate a central dominance of Type 1a supernova (SN Ia) ejecta similar to that found for A496, A2199, and A3571. Simultaneous analysis of ASCA spectra from SIS1, GIS2, and GIS3 shows that the ratio of Ni to Fe abundances is similar to3.4 +/- 1.1 times solar within the central 4'. This ratio is consistent with (and more precise than) that observed in other clusters whose central regions are dominated by SN Ia ejecta. Such a large Ni overabundance is predicted by "convective deflagration" explosion models for SNe Ia such as W7 but is inconsistent with delayed detonation models. We note that with current instrumentation the Ni K alpha line is confused with Fe K beta and that the Ni overabundance we observe has been interpreted by others as an anomalously large ratio of Fe K beta to Fe K alpha caused by resonant scattering in the Fe K alpha line. We argue that a central enhancement of SN Ia ejecta and hence a high ratio of Ni to Fe abundances are naturally explained by scenarios that include the generation of chemical gradients by suppressed SN Ia winds or ram pressure stripping of cluster galaxies. It is not necessary to suppose that the intracluster gas is optically thick to resonant scattering of the Fe K alpha line. C1 Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. NR 68 TC 27 Z9 27 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 FEB 10 PY 2001 VL 548 IS 1 BP 141 EP 149 DI 10.1086/318694 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QN UT WOS:000166939900012 ER PT J AU Gao, Y Lo, KY Lee, SW Lee, TH AF Gao, Y Lo, KY Lee, SW Lee, TH TI Molecular gas and the modest star formation efficiency in the "Antennae" galaxies: Arp 244=NGC 4038/9 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 4038/9); galaxies : interactions; galaxies : starburst; infrared : galaxies; ISM : molecules; stars : formation ID ULTRALUMINOUS INFRARED GALAXIES; MERGING DISK GALAXIES; TO-RADIO RATIO; COLLIDING GALAXIES; SPIRAL GALAXIES; LUMINOUS GALAXIES; IRAS OBSERVATIONS; LINE-INTENSITIES; DENSE GAS; CO AB We report here a factor of 5.7 higher total CO flux in Arp 244 (the "Antennae" galaxies) than that previously accepted in the literature (thus a total molecular gas mass of 1.5 x 10(10) M.), based on our fully sampled CO(1-0) observations at the NRAO 12 m telescope. Currently, much of the understanding and modeling of the star formation in Arp 244 has been derived using a much lower molecular gas mass. It is imperative to reconsider everything, as the high molecular gas mass might provide sufficient fuel for ultraluminous extreme starburst in Arp 244 once the merging advances to late stage. Our observations show that the molecular gas peaks predominately in the disk-disk overlap region between the nuclei, similar to the far-infrared (FIR) and mid-infrared (MIR) emission. The bulk of the molecular gas is forming into stars with a normal star formation efficiency (SFE) L-IR/M(H-2) approximate to 4.2 L./M., the same as that of giant molecular clouds in the Galactic disk. Additional supportive evidence is the extremely low fraction of the dense molecular gas in Arp 244, revealed by our detections of the HCN(1-0) emission, which traces the active star-forming gas at density greater than or similar to 10(4) cm(-3). Using the high-resolution BIMA + NRAO 12 m telescope, full-synthesis CO(1-0) images and our VLA continuum maps at 20 cm, we estimate the local SFE indicated by the ratio map of the radio continuum to CO(1-0) emission, down to kiloparsec scale. Remarkably, the local SFE stays roughly the same over the bulk of the molecular gas distribution. Only some localized regions show the highest radio-to-CO ratios that we have identified as the sites of the most intense starbursts with SFE greater than or similar to 20 L./M. Here we have assumed that the 20 cm emission is a fairly good indicator of star formation down to kiloparsec scale in Arp 244 because of the well-known correlation between the FIR and the radio continuum emission. These starburst regions are confined exclusively to the dusty patches seen in the Hubble Space Telescope optical images near the CO and FIR peaks where the violent starbursts are presumably heavily obscured. Nevertheless, recent large-scale star formation is going on throughout the system (e.g., concentrations of numerous super-star clusters and MIR "hotspots"), yet the measured level is more suggestive of a moderate starburst (SFE greater than or similar to 10 L./M.) or a weak to normal star formation (SFE similar to4 L./M.), not necessarily occurring at the high concentrations of the molecular gas reservoir. The overall starburst from the bulk of the molecular gas is yet to be initiated as most of the gas further condenses into a kiloparsec scale in the final coalescence. C1 CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, Pasadena, CA 91125 USA. Univ Toronto, Dept Astron, Toronto, ON M5S 3H8, Canada. Univ Illinois, Dept Astron, Lab Astron Imaging, Urbana, IL 61801 USA. Acad Sinica, Inst Astron & Astrophys, Taipei 115, Taiwan. Univ Calgary, Dept Phys & Astron, Calgary, AB T2N 1N4, Canada. RP CALTECH, Jet Prop Lab, Ctr Infrared Proc & Anal, 100-22,770 S Wilson Ave, Pasadena, CA 91125 USA. EM gao@ipac.caltech.edu; kyl@asiaa.sinica.edu.tw; swlee@fft.astro.utoronto.ca; thlee@iras.ucalgary.ca RI Lee, Typhoon/N-8347-2013 NR 93 TC 51 Z9 51 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 FEB 10 PY 2001 VL 548 IS 1 BP 172 EP 189 DI 10.1086/318682 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QN UT WOS:000166939900014 ER PT J AU Corbet, RHD Marshall, FE Coe, MJ Laycock, S Handler, G AF Corbet, RHD Marshall, FE Coe, MJ Laycock, S Handler, G TI The discovery of an outburst and pulsed X-ray flux from SMC X-2 using the Rossi X-ray Timing Explorer SO ASTROPHYSICAL JOURNAL LA English DT Article DE stars : individual (SMC X-2); stars : neutron; X-rays : stars ID SMALL MAGELLANIC CLOUD; IN-ORBIT PERFORMANCE; BINARY-SYSTEMS; ACCRETION; MONITOR AB Rossi X-Ray Timing Explorer (RXTE) All-Sky Monitor observations of SMC X-2 show that the source experienced an outburst in 2000 January-April reaching a peak luminosity of greater than similar to 10(38) ergs s(-1). RXTE Proportional Counter Array observations during this outburst reveal the presence of pulsations with a 2.37 s period. However, optical photometry of the optical counterpart shows that the source was still significantly fainter than it was more than a half a year after the outburst in the 1970s when SMC X-2 was discovered. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Washington, DC USA. Univ Southampton, Dept Phys & Astron, Southampton SO17 1BJ, Hants, England. S African Astron Observ, ZA-7935 Cape Town, South Africa. RP Corbet, RHD (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 23 TC 22 Z9 22 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 2001 VL 548 IS 1 BP L41 EP L44 DI 10.1086/318929 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QV UT WOS:000166940500010 ER PT J AU Ebeling, H Jones, LR Fairley, BW Perlman, E Scharf, C Horner, D AF Ebeling, H Jones, LR Fairley, BW Perlman, E Scharf, C Horner, D TI Discovery of a very X-ray luminous galaxy cluster at z=0.89 in the wide angle ROSAT pointed survey SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : clusters : general galaxies : clusters : individual (Cl J1226.9+3332, Cl J0152.7-1357); X-rays : general ID EVOLUTION AB We report the discovery of the galaxy cluster Cl J1226.9+3332 in the Wide Angle ROSAT Pointed Survey (WARPS). At and z = 0.888 and L-x = 1.1 x 10(45) h(50)(-2) ergs s(-1) (0.5-2.0 keV), Cl J1226.9+3332 is the most distant X-ray luminous cluster currently known. The mere existence of this system represents a huge problem for world models Omega (o) = 1 world models At the modest (off-axis) resolution of the ROSAT Position Sensitive Proportional Counter observation in which the system was detected, Cl J1226.9+3332 appears relaxed; an off-axis High Resolution Imager observation confirms this impression and rules out significant contamination from point sources. However, in moderately deep optical images (R and I band), the cluster exhibits signs of substructure in its apparent galaxy distribution. A first crude estimate of the velocity dispersion of the cluster galaxies based on six redshifts yields a high value of 1650 km s(-1), indicative of a very massive cluster and/or the presence of substructure along the line of sight. While a more accurate assessment of the dynamical state of this system requires much better data at both optical and X-ray wavelengths, the high mass of the cluster has already been unambiguously confirmed by a very strong detection of the Sunyaev-Zeldovich effect in its direction. Using Cl J1226.9+3332 and Cl J0152.7-1357 (z = 0.835), the second most distant X-ray luminous cluster currently known and also a WARPS discovery, we obtain a first estimate of the cluster X-ray luminosity function at and 0.8 < z < 1.4 and L-x > 5 x 10(44) h(50)(-2) ergs s(-1) (0.5- 2.0 keV). Using the best currently available data, we find the comoving space density of very distant, massive clusters to be in excellent agreement with the value measured locally (z < 0.3) and conclude that negative evolution is not required at these luminosities out to z 1. Our findings are in conflict with earlier claims of highly significant (>3 sigma) negative evolution already at 0.3 < z < based on the cluster samples of the Einstein Extended Medium-Sensitivity Survey (EMSS) and the Center for Astrophysics 160 degrees survey. Our results agree, however, with the lack of significant evolution of very X-ray luminous clusters out to z similar to 0.4 reported by the MAssive Cluster Survey team. Our findings are also consistent with the abundance of very X-ray luminous clusters at z similar to 0.8 inferred from the EMSS cluster sample, provided Cl J0152.7-1357 (which was missed by the EMSS) is added in. C1 Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Univ Birmingham, Sch Phys & Astron, Birmingham B15 2TT, W Midlands, England. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Ebeling, H (reprint author), Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA. NR 29 TC 49 Z9 49 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 FEB 10 PY 2001 VL 548 IS 1 BP L23 EP L27 DI 10.1086/318915 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QV UT WOS:000166940500006 ER PT J AU Gopalswamy, N Yashiro, S Kaiser, ML Howard, RA Bougeret, JL AF Gopalswamy, N Yashiro, S Kaiser, ML Howard, RA Bougeret, JL TI Radio signatures of coronal mass ejection interaction: Coronal mass ejection cannibalism? SO ASTROPHYSICAL JOURNAL LA English DT Article DE solar-terrestrial relations; Sun : corona; Sun : coronal mass ejections (CMEs) Sun : flares; Sun : prominences; Sun : radio radiation ID EMISSIONS; WIND AB We report the first detection at long radio wavelengths of interaction between coronal mass ejections (CMEs) in the interplanetary medium. The radio signature is in the form of intense continuum-like radio emission following an interplanetary type II burst. At the time of the radio enhancement, coronagraphic images show a fast CME overtaking a slow CME. We interpret the radio enhancement as a consequence of shock strengthening when the shock ahead of the fast CME plows through the core of the preceding slow CME. The duration of the radio enhancement is consistent with the transit time of the CME-driven shock through the core of the slow CME. As a consequence of the interaction, the core of the slow CME changed its trajectory significantly. Based on the emission characteristics of the radio enhancement, we estimate the density of the core of the slow CME to be similar to4 x 10(4) cm(-3). The CME interaction has important implications for space weather prediction based on halo CMEs: some of the false alarms could be accounted for by CME interactions. The observed CME interaction could also explain some of the complex ejecta at 1 AU, which have unusual composition. C1 Catholic Univ Amer, Ctr Solar Phys & Space Weather, Washington, DC 20064 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. USN, Res Lab, Washington, DC 20375 USA. Observ Paris, Meudon, France. RP Gopalswamy, N (reprint author), Catholic Univ Amer, Ctr Solar Phys & Space Weather, 620 Michigan Ave, Washington, DC 20064 USA. RI Gopalswamy, Nat/D-3659-2012 NR 10 TC 180 Z9 185 U1 3 U2 8 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 FEB 10 PY 2001 VL 548 IS 1 BP L91 EP L94 DI 10.1086/318939 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QV UT WOS:000166940500022 ER PT J AU Harding, AK Zhang, B AF Harding, AK Zhang, B TI Off-beam gamma-ray pulsars and unidentified EGRET sources in the Gould Belt SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : observations; gamma rays : theory; open clusters and associations : individual (Gould Belt); pulsars : general; radiation mechanisms : nonthermal ID EMISSION; STATISTICS AB We investigate whether gamma-ray pulsars viewed at a large angle to the neutron star magnetic pole could contribute to the new population of Galactic unidentified EGRET sources associated with the Gould Belt. The faint, soft nature of these sources is distinctly different from both the properties of unidentified EGRET sources along the Galactic plane and the properties of the known gamma-ray pulsars. We explore the possibility, within the polar cap model, that some of these sources are emission from pulsars seen at lines of sight that miss both the bright gamma-ray cone beams and the radio beam. The off-beam gamma rays come from high-altitude curvature emission of primary particles, are radiated over a large solid angle and have a much softer spectrum than that of the main beams. We estimate that the relative detectability of such off-beam emission is about a factor of 4-5 higher than that of the on-beam emission. At least some of the radio-quiet Gould Belt sources detected by EGRET could therefore be such off-beam gamma-ray pulsars. The Gamma-ray Large Area Space Telescope should be able to detect pulsations in most of these sources. 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 Harding, Alice/D-3160-2012 NR 13 TC 34 Z9 34 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 FEB 10 PY 2001 VL 548 IS 1 BP L37 EP L40 DI 10.1086/318931 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QV UT WOS:000166940500009 ER PT J AU Helou, G Malhotra, S Hollenbach, DJ Dale, DA Contursi, A AF Helou, G Malhotra, S Hollenbach, DJ Dale, DA Contursi, A TI Evidence for the heating of atomic interstellar gas by polycyclic aromatic hydrocarbons SO ASTROPHYSICAL JOURNAL LA English DT Article DE dust, extinction; galaxies : ISM; ISM : atoms; ISM : lines and bands ID SMALL GRAINS; EMISSION FEATURES; GALAXIES; MOLECULES; CLOUDS; COLORS; DUST AB We report a strong correlation between the [C II] 158 mum cooling line and the mid-infrared flux in the 5-10 mum range in a wide variety of star-forming galaxies. The mid-infrared flux is dominated by the aromatic features in emission (AFEs), which are thought to arise from large polycyclic aromatic hydrocarbons (PAHs) and are generally associated with the smallest interstellar grains. The [C II] line is the dominant gas coolant in most regions of atomic interstellar gas and therefore reflects the heating input to the gas. The ratio of these two quantities, [C II]/AFE, remains nearly constant around 1.5% against variations in the ratio of the IRAS 60 mum band flux to the 100 mum band flux, R(60/100). This is in contrast to the drop in the [C II]/far-infrared (FIR) ratio with increasing R(60/100), which signals higher dust temperatures and more intense radiation fields. We interpret the stable [C II]/AFE ratio as evidence that gas heating is dominated by the PAHs or small grains, which are also AFE carriers, over a wide range of conditions. The trend of decreasing [C II]/FIR and AFE/FIR with increasing radiation field suggests a decrease in the importance of PAHs or small grains relative to large grains both in gas heating and in dust cooling. We summarize the observed trends and suggest two plausible scenarios. C1 CALTECH, IPAC, Pasadena, CA 91125 USA. Johns Hopkins Univ, Bloomberg Ctr, Baltimore, MD 21210 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Helou, G (reprint author), CALTECH, IPAC, MS 100-22,770 S Wilson Ave, Pasadena, CA 91125 USA. NR 34 TC 53 Z9 53 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 FEB 10 PY 2001 VL 548 IS 1 BP L73 EP L76 DI 10.1086/318916 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QV UT WOS:000166940500018 ER PT J AU Meier, DL AF Meier, DL TI The association of jet production with geometrically thick accretion flows and black hole rotation SO ASTROPHYSICAL JOURNAL LA English DT Article DE black hole physics; galaxies : jets; galaxies : nuclei; hydrodynamics; MHD; quasars : general; radio continuum : galaxies; relativity ID BLANDFORD-ZNAJEK MECHANISM; X-RAY; RADIO GALAXIES; SURFACE PHOTOMETRY; GALACTIC NUCLEI; GRO J1655-40; VARIABILITY; LUMINOSITY; FANAROFF; BEHAVIOR AB A model is presented in which the strongest radio-emitting jet outflows are produced in black hole systems when the accretion is a geometrically thick (H/R similar to 1) inflow (e. g., an advection-dominated or a convection-dominated accretion flow) and if the black hole is rotating. For galactic black hole candidates, the model naturally accounts for the observed correlation of jet outflow with the black hole hard emission state and predicts an association of strong jets with rapid black hole rotation. When extended to the supermassive case, the model accounts for the highest radio galaxy and quasar jet powers and provides additional theoretical support for the "spin paradigm," which asserts that radio-loud quasars are produced by Kerr holes and radio-quiet ones by Schwarzschild holes. In some cases, the angular momentum and energy outflow in the jet may be large enough to alter significantly the structure of the accretion flow from that predicted by current models. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Meier, DL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 35 TC 201 Z9 201 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 FEB 10 PY 2001 VL 548 IS 1 BP L9 EP L12 DI 10.1086/318921 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QV UT WOS:000166940500003 ER PT J AU Romeo, G Ali, S Femenia, B Limon, M Piccirillo, L Rebolo, R Schaefer, R AF Romeo, G Ali, S Femenia, B Limon, M Piccirillo, L Rebolo, R Schaefer, R TI Millimetric ground-based observation of cosmic microwave background radiation anisotropy at delta = +28 degrees SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic microwave background; cosmology : observations AB Results from the third campaign of a ground-based multiband observation of the millimeter emission of the sky from Tenerife (Canary Islands) are presented. The instrument consists of a 0.45 m diameter off-axis telescope equipped with a four-band multimode He-3 cooled photometer working at 1.1, 1.3, 2.1, and 3.1 mm wavelengths. The beam is well approximated by a Gaussian with 1.degrees 35 FWHM at all wavelengths. The wide wavelength coverage of our instrument allows us to characterize and reduce both the atmospheric and Galactic contamination in our data. The cosmic microwave background radiation data is analyzed in six multipole bands whose centers span the range l = 39 to l = 134 at the two longest wavelengths (2.1 and 3.1 mm). A likelihood analysis indicates that we have detected fluctuations in all bands at the two wavelengths. We have evidence of a rise in the angular power spectrum from low to high. Our measured spectrum is consistent with current popular theories of large- scale structure formation, COBE, and other recent balloon-borne experiments with similar wavelength coverage. C1 Univ Delaware, Bartol Res Inst, Sharp Lab 217, Newark, DE 19716 USA. Inst Astrofis Canarias, E-38200 La Laguna, Tenerife, Spain. Princeton Univ, Dept Phys, Princeton, NJ 08544 USA. Univ Wisconsin, Dept Phys, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Imergent ITI, Greenbelt, MD 20771 USA. RP Romeo, G (reprint author), Univ Delaware, Bartol Res Inst, Sharp Lab 217, Newark, DE 19716 USA. RI Schaefer, Robert/C-2119-2016; OI Schaefer, Robert/0000-0003-3692-0223; ROMEO, Giovanni/0000-0002-5535-7803 NR 21 TC 12 Z9 12 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 FEB 10 PY 2001 VL 548 IS 1 BP L1 EP L4 DI 10.1086/318940 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QV UT WOS:000166940500001 ER PT J AU Turner, TJ George, IM Yaqoob, T Kriss, G Crenshaw, DM Kraemer, S Zheng, W Wang, J Nandra, K AF Turner, TJ George, IM Yaqoob, T Kriss, G Crenshaw, DM Kraemer, S Zheng, W Wang, J Nandra, K TI Chandra grating spectroscopy of the Seyfert galaxy Ton S180 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (Ton S180); X-rays : galaxies ID X-RAY PROPERTIES; OPTICALLY SELECTED QUASARS; COMPLETE SAMPLE; SPECTRA AB We present preliminary results from spectral observations of Ton S180 using Chandra and ASCA. The data confirm the presence of the soft excess, but the Chandra Low-Energy Transmission Grating spectrum reveals it to be broad and smooth rather than resolved into individual emission lines. This excess may represent either a primary or reprocessed continuum component or a blend of broad lines from an ionized accretion disk. The occurrence of a similar feature in five other narrow-line Seyfert 1 galaxies leads us to conclude that this soft X-ray component may be a characteristic of sources accreting at a high rate. The X-ray spectrum shows no evidence for absorption lines, indicating that if gas exists in the line of sight then it is in a very high ionization state or has an extreme velocity distribution. The new ASCA data confirm that the narrow component of the Fe K alpha line peaks close to a rest energy of 7 keV, indicating the presence of a significant amount of highly ionized material in the nuclear environs. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Johns Hopkins Univ, Dept Phys & Astron, Ctr Astrophys Sci, Baltimore, MD 21218 USA. Univ Maryland, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Catholic Univ Amer, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Space Res Assoc, Seabrook, MD 20706 USA. RP Turner, TJ (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 660, Greenbelt, MD 20771 USA. NR 30 TC 39 Z9 39 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 FEB 10 PY 2001 VL 548 IS 1 BP L13 EP L16 DI 10.1086/318938 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QV UT WOS:000166940500004 ER PT J AU Walther, JH Koumoutsakos, P AF Walther, JH Koumoutsakos, P TI Three-dimensional Vortex methods for particle-laden flows with two-way coupling SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article DE vortex methods; particle-laden flows; Lagrangian method ID RAYLEIGH-TAYLOR INSTABILITY; 3 DIMENSIONS; SIMULATION; DISPERSION; VISCOSITY; CONVECTION; TURBULENCE; SUSPENSION; ALGORITHM; EQUATIONS AB This paper presents a three-dimensional viscous vortex method for the simulation of particulate flows with two-way coupling, The flow is computed using Lagrangian vortex elements advected with the local velocity, while their strength is modified to account for viscous diffusion, vortex stretching, and generating vorticity induced by the particles. The solid particles move according to viscous drag and gravity, creating vorticity, which is discretised using vortex elements. This method adaptively tracks the evolution of the vorticity field and the generation of new computational elements to account for the vorticity source term. A key aspect of the present scheme is the remeshing of the computational elements to adaptively accommodate the production of vorticity induced by the solid particles, and to ensure sufficient support for the proper resolution of the diffusion equation. High-order moment-conserving formulas are implemented to maintain the adaptive character of the method while they remain local to minimize the computational cost. These formulas are also implemented in the particle-mesh interpolation of the field and particle quantities in the context of a Vortex-in-Cell algorithm, The method is validated against the results of a related finite-difference study for an axisymmetric swirling flow with particles, The method is then applied to the study of a three-dimensional particle blob falling under the effect of gravity, It is shown that drastically different behaviours are found depending on the presence of an initial vorticity field. (C) 2001 Academic Press. C1 ETH Zurich, Inst Computat Sci, CH-8092 Zurich, Switzerland. NASA, Ames 202A1, CTR, Moffett Field, CA 94035 USA. RP Walther, JH (reprint author), ETH Zurich, Inst Computat Sci, CH-8092 Zurich, Switzerland. RI Koumoutsakos, Petros/A-2846-2008; Walther, Jens/D-9549-2015 OI Koumoutsakos, Petros/0000-0001-8337-2122; Walther, Jens/0000-0001-8100-9178 NR 52 TC 21 Z9 21 U1 0 U2 3 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 FEB 10 PY 2001 VL 167 IS 1 BP 39 EP 71 DI 10.1006/jcph.2000.6656 PG 33 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 405YF UT WOS:000167187600003 ER PT J AU Kassinos, SC Reynolds, WC Rogers, MM AF Kassinos, SC Reynolds, WC Rogers, MM TI One-point turbulence structure tensors SO JOURNAL OF FLUID MECHANICS LA English DT Article ID HOMOGENEOUS TURBULENCE; FLOWS; ISOTROPY; SCALES; LAYER AB The dynamics of the evolution of turbulence statistics depend on the structure of the turbulence. For example, wavenumber anisotropy in homogeneous turbulence is known to affect both the interaction between large and small scales (Kida & Hunt 1989), and the non-local effects of the pressure-strain-rate correlation in the one-point Reynolds stress equations (Reynolds 1989: Cambon ct nl. 1992). Good quantitative measures of turbulence structure are easy to construct using two-point or spectral data, but one-point measures are needed for the Reynolds-averaged modelling of engineering flows. Here we introduce a systematic framework for exploring the role of turbulence structure in the evolution of one-point turbulence statistics. Five one-point statistical measures of the energy-containing turbulence structure are introduced and used with direct numerical simulations to analyse the role of turbulence structure in several cases of homogeneous and inhomogeneous turbulence undergoing diverse modes of mean deformation. The one-point structure tensors are found to be useful descriptors of turbulence structure, and lead to a deeper understanding of some rather surprising observations from DNS and experiments. C1 Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Kassinos, SC (reprint author), Stanford Univ, Dept Mech Engn, Stanford, CA 94305 USA. RI Kassinos, Stavros/B-6404-2016 OI Kassinos, Stavros/0000-0002-3501-3851 NR 29 TC 87 Z9 87 U1 0 U2 6 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD FEB 10 PY 2001 VL 428 BP 213 EP 248 DI 10.1017/S0022112000002615 PG 36 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 402XE UT WOS:000167012800010 ER PT J AU Fahey, DW Gao, RS Carslaw, KS Kettleborough, J Popp, PJ Northway, MJ Holecek, JC Ciciora, SC McLaughlin, RJ Thompson, TL Winkler, RH Baumgardner, DG Gandrud, B Wennberg, PO Dhaniyala, S McKinney, K Peter, T Salawitch, RJ Bui, TP Elkins, JW Webster, CR Atlas, EL Jost, H Wilson, JC Herman, RL Kleinbohl, A von Konig, M AF Fahey, DW Gao, RS Carslaw, KS Kettleborough, J Popp, PJ Northway, MJ Holecek, JC Ciciora, SC McLaughlin, RJ Thompson, TL Winkler, RH Baumgardner, DG Gandrud, B Wennberg, PO Dhaniyala, S McKinney, K Peter, T Salawitch, RJ Bui, TP Elkins, JW Webster, CR Atlas, EL Jost, H Wilson, JC Herman, RL Kleinbohl, A von Konig, M TI The detection of large HNO3-containing particles in the winter arctic stratosphere SO SCIENCE LA English DT Article ID POLAR STRATOSPHERES; OZONE DEPLETION; NITRIC-ACID; WATER-VAPOR; DENITRIFICATION; CLOUD; AEROSOL; HNO3; CONDENSATION; NUCLEI AB Large particles containing nitric acid (HNO3) were observed in the 1999/2000 Arctic winter stratosphere. These in situ observations were made over a Large altitude range (16 to 21 kilometers) and horizontal extent (1800 kilometers) on several airborne sampling flights during a period of several weeks. With diameters of 10 to 20 micrometers, these sedimenting particles have significant potential to denitrify the Lower stratosphere. A microphysical model of nitric acid trihydrate particles is able to simulate the growth and sedimentation of these Large sites in the Lower stratosphere, but the nucleation process is not yet known. Accurate modeling of the formation of these Large particles is essential for understanding Arctic denitrification and predicting future Arctic ozone abundances. C1 NOAA, Aeron Lab, Boulder, CO 80305 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80305 USA. Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA. Univ Leeds, Sch Environm, Leeds LS2 9JT, W Yorkshire, England. Rutherford Appleton Lab, Didcot OX11 0QX, Oxon, England. Univ Nacl Autonoma Mexico, Ctr Ciencias Atmosfera, Mexico City 04510, DF, Mexico. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. CALTECH, Div Engn & Appl Sci, Pasadena, CA 91125 USA. ETH Zurich, Lab Atmospharenphys, CH-8093 Zurich, Switzerland. NASA, Jet Prop Lab, Pasadena, CA 91109 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Bay Area Environm Res Inst, San Francisco, CA 94122 USA. Univ Denver, Dept Engn, Denver, CO 80208 USA. Univ Bremen, Inst Environm Phys, D-28334 Bremen, Germany. RP Fahey, DW (reprint author), NOAA, Aeron Lab, Boulder, CO 80305 USA. RI Salawitch, Ross/B-4605-2009; Wennberg, Paul/A-5460-2012; Herman, Robert/H-9389-2012; Sinnhuber, Miriam/A-7252-2013; Carslaw, Ken/C-8514-2009; Gao, Ru-Shan/H-7455-2013; McLaughlin, Richard/I-4386-2013; Ciciora, Steven/I-4916-2013; Atlas, Elliot/J-8171-2015; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Herman, Robert/0000-0001-7063-6424; Carslaw, Ken/0000-0002-6800-154X; Fahey, David/0000-0003-1720-0634 NR 36 TC 209 Z9 211 U1 5 U2 27 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 FEB 9 PY 2001 VL 291 IS 5506 BP 1026 EP 1031 DI 10.1126/science.1057265 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 400EW UT WOS:000166860100041 PM 11161213 ER PT J AU Cardelino, BH Moore, CE Cardelino, CA Frazier, DO Bachmann, KJ AF Cardelino, BH Moore, CE Cardelino, CA Frazier, DO Bachmann, KJ TI Theoretical study of indium compounds of interest for organometallic chemical vapor deposition SO JOURNAL OF PHYSICAL CHEMISTRY A LA English DT Article ID MOLECULAR-ORBITAL THEORY; EXTENDED BASIS-SETS; POTENTIAL-ENERGY SURFACES; DENSITY-FUNCTIONAL THEORY; IR MATRIX-ISOLATION; SPECTROSCOPIC CONSTANTS; DISSOCIATION-ENERGIES; ELECTRONIC STATES; PHASE EPITAXY; PSEUDOPOTENTIAL APPROXIMATION AB The structural, electronic, and thermochemical properties of indium compounds which are of interest in halide transport and organometallic chemical vapor deposition processes have been studied by ab initio and statistical thermodynamic methods. The compounds reported include: indium halides and hydrides (InF, InCl, InCl(3), InH, InH(2), InH(3)); indium clusters (In(2), In(3)); methylindium, dimethylindium, and their hydrogen derivatives [In(CH(3)), In(CH(3))H, In(CH(3))H(2), In(CH(3))(2), In(CH(3))(2)H]; dimethylindium dimer [In(2)(CH(3))(4)] and trimethylindium [In(CH(3))(3)]; dehydrogenated methyl-, dimethyl-, and trimethylindium [In(CH(3))(2)CH(2), In(CH(3))CH(2). In(CH(2))]; trimethylindium adducts with ammonia, trimethylamine and hydrazine [(CH(3))(3)In:NH(3), (CH(3))(3)In:N(CH(3))(3), (CH(3))(3)In:N(H(2))N(H(2))]; dimethylamino-indium and methylimino-indium [In(CH(3))(2)(NH(2)). In(CH(3))(NH)]; indium nitride and indium nitride dimer (InN, In(2)N(2)); indium phosphide, -arsenide, and -antimonide (InP, InAs, InSb). The predicted electronic properties are based on density functional theory calculations; the calculated thermodynamic properties are reported following the format of the JANAF (Joint Army, Navy, NASA, Air Force) Tables. Equilibrium compositions at two temperatures (298 and 1000K) have been analyzed for groups of competing simultaneous reactions. C1 Spelman Coll, Dept Chem, Atlanta, GA 30314 USA. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. N Carolina State Univ, Dept Mat Sci & Engn, Raleigh, NC 27695 USA. RP Cardelino, BH (reprint author), Spelman Coll, Dept Chem, Box 238, Atlanta, GA 30314 USA. EM cardelino@spelman.edu NR 88 TC 23 Z9 23 U1 0 U2 9 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 FEB 8 PY 2001 VL 105 IS 5 BP 849 EP 868 DI 10.1021/jp0013558 PG 20 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 400AF UT WOS:000166845900008 ER PT J AU Lewis, DK Glenar, DA Hughes, S Kalra, BL Schlier, J Shukla, R Baldwin, JE AF Lewis, DK Glenar, DA Hughes, S Kalra, BL Schlier, J Shukla, R Baldwin, JE TI Stereochemistry of the thermal retro-Diels-Alder reactions of cis,exo-5,6-d(2)-bicyclo[2.2.1]hept-2-ene, cis-4,5-d(2)-cyclohexene, and cis,exo-5,6-d(2)-bicyclo[2.2.2]oct-2-ene SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID IDEAL-GAS ENTHALPIES; THERMODYNAMIC PROPERTIES; ENERGY; BICYCLO<2.2.1>HEPT-2-ENE; ISOMERIZATION; BICYCLO<3.2.0>HEPT-2-ENE; CONVERSIONS; NORBORNENE; KINETICS; DYNAMICS C1 Connecticut Coll, Dept Chem, New London, CT 06320 USA. Syracuse Univ, Dept Chem, Syracuse, NY 13244 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Hollins Univ, Dept Chem, Hollins, VA 24020 USA. RP Lewis, DK (reprint author), Connecticut Coll, Dept Chem, New London, CT 06320 USA. NR 30 TC 12 Z9 12 U1 1 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD FEB 7 PY 2001 VL 123 IS 5 BP 996 EP 997 DI 10.1021/ja003805f PG 2 WC Chemistry, Multidisciplinary SC Chemistry GA 399ZJ UT WOS:000166843900033 PM 11456643 ER PT J AU Rivas, C Lake, R Klimeck, G Frensley, WR Fischetti, MV Thompson, PE Rommel, SL Berger, PR AF Rivas, C Lake, R Klimeck, G Frensley, WR Fischetti, MV Thompson, PE Rommel, SL Berger, PR TI Full-band simulation of indirect phonon assisted tunneling in a silicon tunnel diode with delta-doped contacts SO APPLIED PHYSICS LETTERS LA English DT Article ID SI AB Full-band simulations of indirect, phonon assisted, interband tunneling are used to calculate the current-voltage response of a low-temperature molecular-beam-epitaxy-grown silicon tunnel diode with delta-doped contacts. Electron confinement in the contacts results in weak structure in the current-voltage characteristic. The structure is lost when finite lifetime effects are included. The approach uses the nonequilibrium Green function formalism in a second-neighbor sp3s* planar orbital basis. (C) 2001 American Institute of Physics. C1 Univ Texas, Erik Jonsson Sch Engn, Richardson, TX 75083 USA. Raytheon Syst, Dallas, TX 75266 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. IBM Corp, Div Res, Thomas J Watson Res Ctr, Yorktown Heights, NY 10598 USA. USN, Res Lab, Washington, DC 20375 USA. Univ Delaware, Dept Elect & Comp Engn, Newark, DE 19716 USA. RP Rivas, C (reprint author), Univ Texas, Erik Jonsson Sch Engn, Richardson, TX 75083 USA. RI Rommel, Sean/F-9654-2013; Berger, Paul/I-4063-2014; Klimeck, Gerhard/A-1414-2012; Fischetti, Massimo/A-4508-2012 OI Rommel, Sean/0000-0001-5996-0813; Berger, Paul/0000-0002-2656-2349; Klimeck, Gerhard/0000-0001-7128-773X; Fischetti, Massimo/0000-0001-5926-0200 NR 18 TC 46 Z9 46 U1 0 U2 4 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD FEB 5 PY 2001 VL 78 IS 6 BP 814 EP 816 DI 10.1063/1.1343500 PG 3 WC Physics, Applied SC Physics GA 398CF UT WOS:000166737800044 ER PT J AU Rink, C AF Rink, C TI Untitled SO AEROSPACE AMERICA LA English DT Letter C1 NASA, Langley Res Ctr, Hampton, VA 23665 USA. RP Rink, C (reprint author), NASA, Langley Res Ctr, Hampton, VA 23665 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 USA SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD FEB PY 2001 VL 39 IS 2 BP 6 EP 6 PG 1 WC Engineering, Aerospace SC Engineering GA 401KM UT WOS:000166926800005 ER PT J AU Venkataraman, S Haftka, RT Johnson, TF AF Venkataraman, S Haftka, RT Johnson, TF TI Maximal errors due to use of equivalent properties for sublaminates SO AIAA JOURNAL LA English DT Article ID COMPOSITE; DESIGN AB Sublaminates are often used in design optimization to reduce the complexity of the design task, to simplify modeling, to reduce data input to analytical models, and to provide confidence in failure prediction. Sublaminates selected for design often use fixed ratios of ply orientations that have been previously tested and are well characterized. Because ratios of the ply orientations are fixed, designers approximate the properties of sublaminates using equivalent orthotropic properties. The maximal errors in bending stiffness and buckling loads due to use of equivalent properties are investigated. It is found that repeating half of the sublaminate on either side of the symmetry plane results in larger errors than repeating the entire sublaminate. For the former ease, errors of up to about 20% are found even with four sublaminate repetitions, whereas for the latter case, errors were under 6%, Predicted buckling loads exhibit the largest errors when equivalent properties are used for plates with large aspect and load ratios. C1 Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. NASA, Langley Res Ctr, Met & Thermal Struct Branch, Hampton, VA 23681 USA. RP Venkataraman, S (reprint author), Univ Florida, Dept Aerosp Engn Mech & Engn Sci, Gainesville, FL 32611 USA. NR 7 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 0001-1452 J9 AIAA J JI AIAA J. PD FEB PY 2001 VL 39 IS 2 BP 296 EP 302 PG 7 WC Engineering, Aerospace SC Engineering GA 399ZQ UT WOS:000166844500012 ER PT J AU Chien, S Estlin, T Fisher, F Rabideau, G AF Chien, S Estlin, T Fisher, F Rabideau, G TI Lessons learned deploying space planning systems SO APPLIED ARTIFICIAL INTELLIGENCE LA English DT Article ID ACQUISITION; VALIDATION AB This article describes a number of lessons learned in deploying automated planning and scheduling systems for space applications at the Jet Propulsion Laboratory. Specifically, we describe issues relating to how plan representation can affect plan quality; how to acquire, validate and maintain planning knowledge bases; and how planning and execution can be integrated. These issues are described in the context of several fielded systems in the areas of science data analysis, ground station automation, and spacecraft autonomy. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Chien, S (reprint author), CALTECH, Jet Prop Lab, MS 126-347, Pasadena, CA 91109 USA. NR 29 TC 0 Z9 0 U1 0 U2 1 PU TAYLOR & FRANCIS INC PI PHILADELPHIA PA 325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA SN 0883-9514 J9 APPL ARTIF INTELL JI Appl. Artif. Intell. PD FEB PY 2001 VL 15 IS 2 BP 161 EP 187 DI 10.1080/088395101750065750 PG 27 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 402LY UT WOS:000166989900004 ER PT J AU Haeffelin, M Kato, S Smith, AM Rutledge, CK Charlock, TP Mahan, JR AF Haeffelin, M Kato, S Smith, AM Rutledge, CK Charlock, TP Mahan, JR TI Determination of the thermal offset of the Eppley precision spectral pyranometer SO APPLIED OPTICS LA English DT Article ID SURFACE SHORTWAVE IRRADIANCE; RADIATION; ATMOSPHERES; SCATTERING AB Eppley's precision spectral pyranometer (PSP) is used in networks around the world to measure down-welling diffuse and global solar irradiance at the surface of the Earth. In recent years several studies have shown significant discrepancy between irradiances measured by pyranometers and those computed by atmospheric radiative transfer models. Pyranometer measurements have been questioned because observed diffuse irradiances sometimes are below theoretical minimum values for a pure molecular atmosphere, and at night the instruments of ten produce nonzero signals ranging between +5 and -10 W m(-2). We install thermistor sondes in the body of a PSP as well as on its inner dome to monitor the temperature gradients within the instrument, and we operate a pyrgeometer (PIR) instrument side by side with the PSP. We derive a relationship between the PSP output and thermal radiative exchange by the dome and the detector and a relationship between the PSP output and the PIR thermopile output (net-IR). We determine the true PSP offset by quickly capping the instrument at set time intervals. For a ventilated and shaded PSP, the thermal offset can reach -15 W m(-2) under clear skies, whereas it remains close to zero for low overcast clouds. We estimate the PSP thermal offset by two methods: (1) using the PSP temperatures and (2) using the PIR net-IR signal. The offset computed from the PSP temperatures yields a reliable estimate of the true offset (+/-1 W m(-2)). The offset computed from net-IR is consistent with the true offset at night and under overcast skies but predicts only part of the true range under clear skies. (C) 2001 Optical Society of America. C1 Virginia Polytech Inst & State Univ, Blacksburg, VA 24061 USA. Hampton Univ, Hampton, VA 23668 USA. Analyt Sci & Mat, Hampton, VA 23666 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Haeffelin, M (reprint author), Virginia Polytech Inst & State Univ, Blacksburg, VA 24061 USA. EM m.p.haeffelin@larc.nasa.gov NR 28 TC 39 Z9 40 U1 1 U2 4 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 FEB 1 PY 2001 VL 40 IS 4 BP 472 EP 484 DI 10.1364/AO.40.000472 PG 13 WC Optics SC Optics GA 396QF UT WOS:000166647500007 PM 18357021 ER PT J AU Kunieda, H Ishida, M Endo, T Hidaka, Y Honda, H Imamura, K Ishida, J Maeda, M Misaki, K Shibata, R Furuzawa, A Haga, K Ogasaka, Y Okajima, T Tawara, Y Terashima, Y Watanabe, M Yamashita, K Yoshioka, T Serlemitsos, PJ Soong, Y Chan, KW AF Kunieda, H Ishida, M Endo, T Hidaka, Y Honda, H Imamura, K Ishida, J Maeda, M Misaki, K Shibata, R Furuzawa, A Haga, K Ogasaka, Y Okajima, T Tawara, Y Terashima, Y Watanabe, M Yamashita, K Yoshioka, T Serlemitsos, PJ Soong, Y Chan, KW TI X-ray telescope onboard Astro-E: optical design and fabrication of thin foil mirrors SO APPLIED OPTICS LA English DT Article ID CALIBRATION AB X-ray telescopes (XRT 's) of nested thin foil mirrors are developed for Astro-E, the fifth Japanese x-ray astronomy satellite. Although the launch was not successful, the design concept, fabrication, and alignment procedure are summarized. The main Purpose of the Astro-E XRT is to collect hard x rays up to 10 keV with high efficiency and to provide medium spatial resolution in limited weight and volume. Compared with the previous mission, Advanced Satellite for Cosmology and Astrophysics (ASCA), a slightly longer focal length of 4.5-4.75 m and a larger diameter of 40 cm yields an effective area of 1750 cm(2) at 8 keV with five telescopes. The image quality is also improved to 2-arc min half-power diameter by introduction of a replication process. Platinum is used instead of gold for the reflectors of one of the five telescopes to enhance the high-energy response. The fabrication and alignment procedure is also summarized. Several methods for improvement are suggested for the reflight Astro-E II mission and for other future missions. Preflight calibration results will be described in a forthcoming second paper, and a detailed study of images will be presented in a third paper. (C) 2001 Optical Society of America. C1 Inst Space & Astronaut Sci, Kanagawa 2298510, Japan. Nagoya Univ, Dept Phys, Nagoya, Aichi 4648602, Japan. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Kunieda, H (reprint author), Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Kanagawa 2298510, Japan. EM kunieda@astro.isas.ac.jp NR 15 TC 47 Z9 49 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD FEB 1 PY 2001 VL 40 IS 4 BP 553 EP 564 DI 10.1364/AO.40.000553 PG 12 WC Optics SC Optics GA 396QF UT WOS:000166647500017 PM 18357031 ER PT J AU Andreev, AA Peteet, DM Tarasov, PE Romanenko, FA Filimonova, LV Sulerzhitsky, LD AF Andreev, AA Peteet, DM Tarasov, PE Romanenko, FA Filimonova, LV Sulerzhitsky, LD TI Late Pleistocene interstadial environment on Faddeyevskiy Island, East-Siberian sea, Russia SO ARCTIC ANTARCTIC AND ALPINE RESEARCH LA English DT Article ID VEGETATION AB Pollen, plant macrofossil, loss-on-ignition and radiocarbon analyses of a 1.4-m section in thermokarst topography from Faddeyevskiy Island (75 degrees 20'N, 143 degrees 50'E, 30 m elevation) provides new information on Late Pleistocene interstadial environmental history of this high Arctic region. Conventional radiocarbon dates (25,700 +/- 1000, 32,780 +/- 500, 35,200 +/- 650 yr BP) and two AMS dates (29,950 +/- 660 and 42,990 +/- 1280 yr BP) indicate that the deposits accumulated during the Kargian (Boutellier) interval. Numerous mammoth (Mammuthus primigenius) remains that have been collected in vicinity of the site in this study were radiocarbon dated to 36,700-18,500 yr BP. Rare bison (Bison priscus) bones were dated to 32,200 +/- 600 and 33,100 +/- 320 yr BP. Poaceae, Cyperaceae, and Artemisia pollen dominate the spectra with some Ranunculaceae, Caryophyllaceae, Rosaceae, and Asteraceae. The pollen spectra reflect steppe-like (tundra-steppe) vegetation, which was dominant on the exposed shelf of the Arctic Ocean. Numerous Carex macrofossils suggest that the summer climate was at least 2 degreesC warmer than today. The productivity of the local vegetation during the Kargian interstadial was high enough to feed the population of grazing mammals. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Russian Acad Sci, Inst Geog, Moscow 109017, Russia. Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA. Moscow MV Lomonosov State Univ, Dept Geog, Moscow 119899, Russia. Russian Acad Sci, Inst Biol, Petrozavodsk 185610, Russia. Russian Acad Sci, Inst Geol, Moscow 109017, Russia. RP Andreev, AA (reprint author), Alfred Wegener Inst Polar & Meeresforsch, Forsch Stelle Potsdam, Telegrafenberg A43, D-14473 Potsdam, Germany. RI Andreev, Andrei/J-2701-2015 NR 48 TC 7 Z9 7 U1 0 U2 6 PU INST ARCTIC ALPINE RES PI BOULDER PA UNIV COLORADO, BOULDER, CO 80309 USA SN 1523-0430 J9 ARCT ANTARCT ALP RES JI Arct. Antarct. Alp. Res. PD FEB PY 2001 VL 33 IS 1 BP 28 EP 35 DI 10.2307/1552274 PG 8 WC Environmental Sciences; Geography, Physical SC Environmental Sciences & Ecology; Physical Geography GA 409JX UT WOS:000167381500004 ER PT J AU Barger, AJ Cowie, LL Mushotzky, RF Richards, EA AF Barger, AJ Cowie, LL Mushotzky, RF Richards, EA TI The nature of the hard X-ray background sources: Optical, near-infrared, submillimeter, and radio properties SO ASTRONOMICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : active; galaxies : distances and redshifts; galaxies : evolution; galaxies : formation; quasars : general ID SPECTRAL ENERGY-DISTRIBUTIONS; ACTIVE GALACTIC NUCLEI; HUBBLE DEEP FIELD; HIGH-REDSHIFT; GALAXY FORMATION; STAR-FORMATION; LOCKMAN FIELD; ROSAT; ASCA; QUASARS AB With recent Chandra observations, at least 60% of the X-ray background in the 2-10 keV energy range is now resolved into discrete sources. Here we present deep optical, near-infrared, submillimeter, and 20 cm (radio) images, as well as high-quality optical spectra, of a complete sample of 20 sources selected to lie above a 2-10 keV flux of 3.8 x 10(-15) ergs cm(-2) s(-1) in a deep Chandra observation of the Hawaii Deep Survey Field SSA13. The 13 galaxies with I < 23.5 have redshifts in the range 0.1 to 2.6. Two are quasars, five show active galactic nucleus (AGN) signatures, and six are z < 1.5 luminous bulge-dominated galaxies whose spectra show no obvious optical AGN signatures. The seven spectroscopically unidentified I > 23.5 sources have colors that are consistent with evolved early galaxies at z = 1.5-3. Only one hard X-ray source is significantly detected in an ultradeep submillimeter map; from the submillimeter to radio flux ratio we estimate a millimetric redshift in the range 1.2-2.4. None of the remaining 19 hard X-ray sources is individually detected in the submillimeter. These results probably reflect the fact that the 850 km flux limits obtainable with SCUBA are quite close to the expected fluxes from obscured AGNs. The ensemble of hard X-ray sources contribute about 10% of the extragalactic background light at submillimeter wavelengths. From the submillimeter and radio data we obtain bolometric far-infrared luminosities. The hard X-ray sources have an average ratio of bolometric far-infrared to 2-10 keV luminosity of about 60, similar to that of local obscured AGNs. The same ratio for a sample of submillimeter-selected sources is in excess of 1100; this suggests that their far-infrared light is primarily produced by star formation. Our data show that luminous hard X-ray sources are common in bulge-dominated optically luminous galaxies, with about 10% of the population showing activity at any given time. We use our measured bolometric corrections with the 2-10 keV extragalactic background light to infer the growth of supermassive black holes. Even with a high radiative efficiency of accretion (epsilon = 0.1), the black hole mass density required to account for the observed light is comparable to the local black hole mass density. C1 Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Arizona State Univ, Tempe, AZ 85287 USA. RP Barger, AJ (reprint author), Univ Hawaii, Inst Astron, 2680 Woodlawn Dr, Honolulu, HI 96822 USA. NR 94 TC 192 Z9 192 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2001 VL 121 IS 2 BP 662 EP 682 DI 10.1086/318742 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QL UT WOS:000166939700007 ER PT J AU Parker, JW Zaritsky, D Stecher, TP Harris, J Massey, P AF Parker, JW Zaritsky, D Stecher, TP Harris, J Massey, P TI Ultraviolet and optical observations of OB associations and field stars in the southwest region of the large Magellanic Cloud SO ASTRONOMICAL JOURNAL LA English DT Article DE Magellanic Clouds; open clusters and associations; stars : early type; stars : mass function; ultraviolet : stars; catalogs ID INITIAL MASS FUNCTION; IMAGING TELESCOPE OBSERVATIONS; STELLAR CONTENT; SPECTRAL CLASSIFICATION; EXTINCTION CURVES; PHOTOMETRY; LMC; 30-DORADUS; EVOLUTION; N-11 AB Using ultraviolet photometry from the Ultraviolet Imaging Telescope (UIT) combined with photometry and spectroscopy from three ground-based optical data sets we have analyzed the stellar content of OB associations and field areas in and around the regions N79, N81, N83, and N94 in the Large Magellanic Cloud. In particular, we compare data for the OB association Lucke-Hodge 2 (LH 2) to determine how strongly the initial mass function (IMF) may depend on different photometric reductions and calibrations. Although the data sets exhibit median photometric differences of up to 30%, the resulting uncorrected IMFs are reasonably similar, typically Gamma similar to -1.6 in the 5-60 M. mass range. M _ However, when we correct for the background contribution of field stars, the calculated IMF flattens to Gamma = 1.3 +/- 0.2 (similar to the Salpeter IMF slope). This change underlines the importance of correcting for field star contamination in determinations of the IMF of star formation regions. It is possible that even in the case of an universal IMF, the variability of the density of background stars could be the dominant factor creating the differences between calculated IMFs for OB associations. We have also combined the UIT data with the most extensive of these ground-based optical data sets-the Magellanic Cloud Photometric Survey-to study the distribution of the candidate O-type stars in the field. We find a significant fraction, roughly half, of the candidate O-type stars are found in field regions, far from any obvious OB associations (in accord with the 1982 suggestions of Garmany, Conti, & Chiosi for O-type stars in the solar neighborhood). These stars are greater than 2' (30 pc) from the boundaries of existing OB associations in the region, which is a distance greater than most O-type stars with typical dispersion velocities will travel in their lifetimes. The origin of these massive field stars (either as runaways, members of low-density star-forming regions, or examples of isolated massive star formation) will have to be determined by further observations and analysis. C1 SW Res Inst, Boulder, CO 80302 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Santa Cruz, Univ Calif Observ, Lick Observ, Santa Cruz, CA 95064 USA. Univ Calif Santa Cruz, Board Astron & Astrophys, Santa Cruz, CA 95064 USA. Lowell Observ, Flagstaff, AZ 86001 USA. RP Parker, JW (reprint author), SW Res Inst, Suite 426,1050 Walnut St, Boulder, CO 80302 USA. EM joel@boulder.swri.edu; dzaritsky@as.arizona.edu; stecher@uit.gsfc.nasa.gov; jharris@ucolick.org; massey@lowell.edu OI Massey, Philip/0000-0001-6563-7828 NR 54 TC 28 Z9 28 U1 0 U2 1 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 FEB PY 2001 VL 121 IS 2 BP 891 EP 904 DI 10.1086/318765 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QL UT WOS:000166939700022 ER PT J AU Smith, N Jones, TJ Gehrz, RD Klebe, D Creech-Eakman, MJ AF Smith, N Jones, TJ Gehrz, RD Klebe, D Creech-Eakman, MJ TI Thermal infrared imaging of the bipolar HII region S106 SO ASTRONOMICAL JOURNAL LA English DT Article DE HII regions; ISM : individual (S106); stars : formation ID H-II REGION; NEBULA; IMAGES; RADIO; S-106 AB The extended infrared emission from Sharpless 106 shows complex structure in ground-based images obtained at wavelengths from 3 to 20 mum. The structure of the ionization fronts and photodissociation regions are resolved in Bra emission at 4.05 mum and emission from polycyclic aromatic hydrocarbons at 3.29 mum, with the H I emission residing interior to the hydrocarbon emission. The mid-infrared observations at 10 to 20 mum reveal the distribution of continuum emission from warm dust in the nebula. These images have a higher spatial resolution than previous mid-infrared maps, but they support earlier findings of a relatively constant dust color temperature of similar to 135 K in the extended dust, excluding the dust near the self-luminous sources IRS 2 and 4. All infrared images presented here show a dark lane bisecting the nebula, which probably results from shadowing of light from the central engine rather than line-of-sight extinction. If this shadow is caused by a compact disk around IRS 4, its ionized inner edge would be within the radio photosphere of the stellar wind at wavelengths longer than about 1.5 cm. There appears to be a faint point source seen at near-infrared wavelengths that is coincident with the position of a bright far-infrared source. This source is adjacent to some bright near-infrared nebulosity but is not clearly detected in thermal infrared dust emission. C1 Univ Minnesota, Dept Astron, Minneapolis, MN 55455 USA. Univ Denver, Dept Phys & Astron, Denver, CO 80208 USA. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. RP Smith, N (reprint author), Univ Minnesota, Dept Astron, 116 Church St SE, Minneapolis, MN 55455 USA. NR 17 TC 14 Z9 14 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2001 VL 121 IS 2 BP 984 EP 991 DI 10.1086/318761 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QL UT WOS:000166939700028 ER PT J AU Ressler, ME Barsony, M AF Ressler, ME Barsony, M TI A luminous infrared companion in the young triple system WL 20 SO ASTRONOMICAL JOURNAL LA English DT Article DE binaries : close; stars : formation; stars : individual (WL 20); stars : pre-main-sequence ID RHO-OPHIUCHI CLOUD; SPECTRAL ENERGY-DISTRIBUTIONS; INITIAL MASS FUNCTION; STELLAR OBJECTS; STAR-FORMATION; DARK CLOUD; T-TAURI; EVOLUTIONARY STATUS; SCORPIO-CENTAURUS; IRAS OBSERVATIONS AB We present spatially resolved near- and mid-infrared (1-25 mum) imaging of the WL 20 triple system in the nearby (d = 125 pc) rho Ophiuchi star-forming cloud core. We find WL 20 to be a new addition to the rare class of "infrared companion systems," with WL 20 E and WL 20 W displaying Class II (T Tauri star) spectral energy distributions (SEDs) and total luminosities of 0.61 and 0.39 L., respectively, and WL 20 S, the infrared companion, having a Class I (embedded protostellar) SED and a luminosity of 1.0-1.8 L.. WL 20 S is found to be highly variable over timescales of years, to be extended (40 AU diameter) at mid-IR wavelengths, and to be the source of the centimeter emission in the system. The photospheric luminosities of 0.53 L. for WL 20 E and 0.35 L. for WL 20 W estimated from our data, combined with existing, spatially resolved near-IR spectroscopy, allow us to compare and test current pre-main-sequence evolutionary tracks. The most plausible, nonaccreting tracks describing this system are those of D'Antona & Mazzitelli published in 1998. These tracks give an age of (2-2.5) x 10(6) yr and masses of 0.62-0.68 M. for WL 20 E and 0.51-0.55 for WL 20 W. The age and mass of WL 20 S cannot be well determined from the currently available data. WL 20 E and W fall into the region of the H-R diagram in which sources may appear up to twice as old as they actually are using nonaccreting tracks, a fact that may reconcile the coexistence of two T Tauri stars with an embedded protostar in a triple system. The derived masses and observed projected separations of the components of the WL 20 triple system indicate that it is in an unstable dynamical configuration, and it may therefore provide an example of dynamical evolution during the pre-main-sequence phase. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Space Sci Inst, Boulder, CO 80303 USA. RP Ressler, ME (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 41 TC 21 Z9 21 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2001 VL 121 IS 2 BP 1098 EP 1110 DI 10.1086/318753 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QL UT WOS:000166939700040 ER PT J AU Povich, MS Giampapa, MS Valenti, JA Tilleman, T Barden, S Deming, D Livingston, WC Pilachowski, C AF Povich, MS Giampapa, MS Valenti, JA Tilleman, T Barden, S Deming, D Livingston, WC Pilachowski, C TI Limits on line bisector variability for stars with extrasolar planets SO ASTRONOMICAL JOURNAL LA English DT Article DE line : profiles; planetary systems; stars : late-type ID RADIAL-VELOCITY; 51-PEGASI; ANDROMEDAE; PULSATIONS; COMPANION; ABSENCE; SPECTRA AB We present an analysis of high-resolution synoptic spectra of ten F- and G-type stars, seven of which exhibit periodic radial velocity variations due to the presence of one or more substellar companions. We searched for subtle periodic variations in photospheric line asymmetry, as characterized by line bisectors. In principle, periodic variations in line asymmetry observed at lower spectral resolution could mimic the radial velocity signature of a companion, but we find no significant evidence of such behavior in our data. Observations were obtained from 1998 March to 1999 February using the National Solar Observatory (NSO) 1.52 m McMath-Pierce Solar Telescope Facility on Kitt Peak in conjunction with the solar-stellar spectrograph, achieving a resolving power of 1.2 x 10(5). To characterize line asymmetry, we first measured line bisectors for the unblended Fe I photospheric line at 625.26 nm. To improve sensitivity to small fluctuations, we then combined points in each bisector to form a velocity displacement with respect to the line core. We searched for periodic variations in this displacement, finding no substantial difference between stars with substellar companions and those without reported companions. We find no correlation between bisector velocity displacement and the known orbital phase of substellar companions around our target stars. Simulations of a periodic signal with noise levels that mimic our measurement errors suggest that we can exclude bisector variations with amplitudes greater than about 20 m s(-1). These results support the conclusion that extrasolar planets best explain the observed periodic variations in radial velocity. C1 Natl Opt Astron Observ, Natl Solar Observ, Tucson, AZ 85726 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Povich, MS (reprint author), Natl Opt Astron Observ, Natl Solar Observ, POB 26732, Tucson, AZ 85726 USA. NR 17 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 2001 VL 121 IS 2 BP 1136 EP 1146 DI 10.1086/318745 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QL UT WOS:000166939700043 ER PT J AU Dumas, C Terrile, RJ Brown, RH Schneider, G Smith, BA AF Dumas, C Terrile, RJ Brown, RH Schneider, G Smith, BA TI Hubble Space Telescope NICMOS spectroscopy of Charon's leading and trailing hemispheres SO ASTRONOMICAL JOURNAL LA English DT Article DE planets and satellites : individual (Charon); techniques : spectroscopic ID WATER ICE; SURFACE-COMPOSITION; CRYSTALLINE WATER; SATELLITE CHARON; ALBEDO MAPS; H2O ICE; PLUTO; METHANE; TEMPERATURE; SYSTEM AB We used the near-infrared camera and multiobject spectrometer NICMOS on the Hubble Space Telescope to obtain 1.1-2.4 km, low-resolution (R similar to 200) slitless grism spectrophotometry of the individual members of the Pluto-Charon system. Water ice is present in its crystalline state on both the leading and trailing hemispheres of Charon. A 2.21 km absorption band, possibly due to the presence of ammonia hydrate in surface, is detected in the reflectance spectrum of its leading side only. Geological activity on Charon or implantation of ions escaped from Pluto's atmosphere could account for the formation of species such as NH(3).H(2)O locally on the satellite. We also measured a slightly higher geometric albedo for Charon than reported from the mid-1980s observations of the mutual events. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Univ Arizona, Steward Observ, Tucson, AZ 85721 USA. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. RP Dumas, C (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 183-501, Pasadena, CA 91109 USA. NR 45 TC 46 Z9 46 U1 0 U2 1 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 FEB PY 2001 VL 121 IS 2 BP 1163 EP 1170 DI 10.1086/318747 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 401QL UT WOS:000166939700046 ER PT J AU Bocchino, F Parmar, AN Mereghetti, S Orlandini, M Santangelo, A Angelini, L AF Bocchino, F Parmar, AN Mereghetti, S Orlandini, M Santangelo, A Angelini, L TI X-ray emission in the direction of the SNR G318.2+0.1 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE supernovae : general; ISM : individual object : G318.2+0.1; ISM : supernova remnants; X-rays : ISM ID ASTRONOMY SATELLITE; ON-BOARD; CATALOG; REGION AB We report the discovery of three X-ray sources within the radio shell G318.2+0.1, one of which may be extended. Two of the sources were detected during the BeppoSAX Galactic Plane Survey and one was found in archival ROSAT data. The fainter BeppoSAX source is coincident with an ultra-compact galactic H II region, and we discuss the possibility that it can he a flaring young stellar object, while the other BeppoSAX source has no obvious counterpart. The PSPC source is consistent with emission from a foreground star. The hard spectrum of the brighter BeppoSAX source is consistent with a non-thermal origin, although a thermal nature cannot be formally excluded. If this source is associated with G318.2+0.1, then its hard spectrum suggests that it may be site of noil-thermal electron acceleration. C1 European Space Agcy, Estec, Dept Space Sci, Div Astrophys, NL-2200 AG Noordwijk, Netherlands. Osservatorio Astron Palermo, I-90134 Palermo, Italy. CNR, Ist Fis Cosm & Tecnol Relat, I-20133 Milan, Italy. CNR, Ist Tecnol & Studio Radiazioni Extraterrestri, I-40129 Bologna, Italy. CNR, Ist Fis Cosm & Applicazioni Informat, I-90146 Palermo, Italy. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Bocchino, F (reprint author), European Space Agcy, Estec, Dept Space Sci, Div Astrophys, Post Bus 299, NL-2200 AG Noordwijk, Netherlands. EM fbocchin@estec.esa.nl RI Orlandini, Mauro/H-3114-2014; OI Orlandini, Mauro/0000-0003-0946-3151; Bocchino, Fabrizio/0000-0002-2321-5616 NR 28 TC 5 Z9 5 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 FEB PY 2001 VL 367 IS 2 BP 629 EP 634 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 408UD UT WOS:000167345300028 ER PT J AU Loewenstein, M Valinia, A Mushotzky, RF AF Loewenstein, M Valinia, A Mushotzky, RF TI RXTE investigation into extended hard X-ray emission from elliptical galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : clusters : individual (Virgo); galaxies : halos; galaxies : individual (NGC 4472, NGC 4649); intergalactic medium; X-rays : galaxies ID VIRGO CLUSTER; ASCA; ROSAT; NGC-4472; METALLICITY; MECHANISMS; ABUNDANCE; NGC-4636; NGC-1399; SAMPLE AB We present results of the first RXTE investigation of hard X-ray emission from normal elliptical galaxies. Joint spectral analysis of RXTE Proportional Counter Array and ASCA Gas Imaging Spectrometer data for NGC 4472 and NGC 4649 reveals the presence of similar to5 x 10(-12) ergs cm(-2) s(-1) of 2-10 keV emission emanating from a region outside of the optical galaxy and of a spectral hardness intermediate between the galactic hot interstellar gas and X-ray binary components. A large fraction of this emission originates in the Virgo intracluster medium (ICM), and we present constraints on the ICM temperature and metallicity in the vicinity of these two galaxies. However, the diffuse flux is significantly greater than expected based on the soft X-ray intensity measured with ROSAT, allowing for the possible presence of an additional diffuse nonthermal component. We also derive new constraints on the integrated X-ray binary emission from these two galaxies and on the presence of a nuclear flat-spectrum point source. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Dept Astron, College Pk, MD 20742 USA. RP Loewenstein, M (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 29 TC 2 Z9 2 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 FEB 1 PY 2001 VL 547 IS 2 BP 722 EP 730 DI 10.1086/318419 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397ZF UT WOS:000166728300018 ER PT J AU Park, S Ebisawa, K AF Park, S Ebisawa, K TI ASCA observation of an "X-ray shadow" in the Galactic plane SO ASTROPHYSICAL JOURNAL LA English DT Article DE diffuse radiation; Galaxy : structure; ISM : structure; X-rays : ISM ID IRON LINE; RIDGE; EMISSION; BULGE; GAS AB The diffuse X-ray background (DXB) emission near the Galactic plane has been (l, b similar to 25 degrees .6,0 degrees .78) observed with ASCA. The observed region is toward a Galactic molecular cloud that was recently reported to cast a deep X-ray shadow in the 0.5-2.0 keV band DXB. The selection of this particular region is intended to provide a constraint on the spatial distribution of the DXB emission along the line of sight : i.e., the molecular cloud is optically thick at less than 2 keV, so the bulk of the observed soft X-rays must originate in the foreground of the cloud, which is at similar to3 kpc from the Sun. In the 0.8-9.0 keV band, the observed spectrum is primarily from multiple components of thermal plasmas. We report here a detection of soft X-ray (0.5-2 keV) emission from an similar to 10(7) K thermal plasma. Comparisons with the ROSAT data suggest that this soft X-ray emission is absorbed by N-H = 1-3 x 10(21) cm(-2), which implies a path-length through the soft X-ray-emitting regions of less than or similar to1 kpc from the Sun. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Park, S (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 662, Greenbelt, MD 20771 USA. NR 32 TC 2 Z9 2 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 FEB 1 PY 2001 VL 547 IS 2 BP 777 EP 785 DI 10.1086/318387 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397ZF UT WOS:000166728300023 ER PT J AU Baring, MG Harding, AK AF Baring, MG Harding, AK TI Photon splitting and pair creation in highly magnetized pulsars SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : theory; magnetic fields; pulsars : general; radiation mechanisms : general; stars : neutron ID X-RAY PULSAR; NEUTRON-STARS; POLAR CAPS; COMPTON-SCATTERING; FIELDS; EMISSION; GAPS; RADIATION; CASCADES; BURSTS AB The absence of radio pulsars with long periods has lead to the popular notion of a high-P "death line." In the standard picture, beyond this boundary, pulsars with low spin rates cannot accelerate particles above the stellar surface to high enough energies to initiate pair cascades, and the pair creation needed for radio emission is strongly suppressed. In this paper we explore the possibility of another pulsar "death line" in the context of polar cap models, corresponding to high magnetic fields B in the upper portion of the period-period derivative diagram, a domain where few radio pulsars are observed. The origin of this high-B boundary, which may occur when B becomes comparable to or exceeds B-cr = 4.4 x 10(13) G, is also due to the suppression of magnetic pair creation, but primarily because of ineffective competition with magnetic photon splitting. Threshold pair creation also plays a prominent role in the suppression of cascades. We present Monte Carlo calculations of the pair yields in photon splitting/ pair cascades that show that, in the absence of scattering effects, pair production is effectively suppressed, but only if all three modes of photon splitting allowed by QED are operating in high fields. This paper describes the probable shape and position of the new "death line," above which pulsars are expected to be radio-quiet, but perhaps still X-ray- and gamma-ray-bright. The hypothesized existence of radio-quiet sources finds dramatic support in the recent discovery of ultrastrong fields in soft gamma-ray repeaters and anomalous X-ray pulsars. Guidelines for moderate- to high-B pulsar searches at radio wavelengths and also in the soft and hard gamma-ray bands are presented. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. RP Baring, MG (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 99 TC 94 Z9 96 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 FEB 1 PY 2001 VL 547 IS 2 BP 929 EP 948 DI 10.1086/318390 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397ZF UT WOS:000166728300035 ER PT J AU Ragot, BR AF Ragot, BR TI Magnetic field line wandering and shock-front acceleration: Application to the radio emission of SN 1987A SO ASTROPHYSICAL JOURNAL LA English DT Article DE acceleration of particles; chaos; diffusion; magnetic fields; shock waves; turbulence ID QUASI-PERPENDICULAR SHOCKS; COSMIC-RAY ELECTRONS; PARTICLE-ACCELERATION; ANOMALOUS TRANSPORT; SUPERNOVA REMNANT; PLASMAS; WAVES AB The superposition of random fluctuations deltaB on a main, regular magnetic field B-0 has been shown by Ragot to produce, on the scales of interest, a nondiffusive random walk of the magnetic field lines in the quasi-linear regime of turbulence. The spreading [Deltax(2)] of the field lines across the direction of B-0 increases as z(beta), z being the distance along B-0 with a transport exponent beta that is not necessarily equal to 1. This puts into question the diffusivity of magnetic field lines in a non-quasi-linear regime as well and could imply an anomalous transport of the cosmic rays accelerated at a shock front if their decorrelation time from the field lines is longer than their acceleration time. Under the assumption of such a long decorrelation time, the acceleration time of cosmic rays scattered along the wandering field lines is derived here as a function of the obliquity and speed of the shock for a general transport exponent of the field lines. It is shown that for high-speed shocks, the importance of magnetic field line wandering (MFLW) is not limited to quasi-perpendicular shocks as usually believed. Moreover, the turbulence ahead of the shock is in a non-quasi-linear regime on the length scale traveled by accelerated particles whenever MFLW is important. The inclusion of MFLW can make the acceleration time depart by orders of magnitude from its value estimated in the approximation of simple scattering. This discrepancy is actually most welcome to explain the acceleration time of GeV electrons at the reappearance of SN 1987A in the radio waveband, since the inferred diffusion coefficient along the shock normal is about 5 orders of magnitude greater than the limiting Bohm value of a cross-field scattering coefficient. From the requirement of a "realistic" turbulence spectrum and in the approximation of quasi-linear transport coefficients, it is found that the magnetic field lines ahead of the SN 1987A shock strongly supradiffuse (beta approximate to 1.8) and that the compression ratio of the shock is larger than 3. Finally, this paper argues in favor of a radio silence of SN 1987A prior to 1990 due to a lack of scattering of the GeV electrons when the shock speed exceeds about one-tenth of the speed of light. C1 NASA, Goddard Space Flight Ctr, High Energy Phys Lab, Greenbelt, MD 20771 USA. RP Ragot, BR (reprint author), Univ Texas, Dept Astron, RLM 15308, Austin, TX 78712 USA. NR 33 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 FEB 1 PY 2001 VL 547 IS 2 BP 1010 EP 1023 DI 10.1086/318404 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397ZF UT WOS:000166728300042 ER PT J AU Corcoran, MF Ishibashi, K Swank, JH Petre, R AF Corcoran, MF Ishibashi, K Swank, JH Petre, R TI The X-ray light curve of eta Carinae: Refinement of the orbit and evidence for phase-dependent mass loss SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; stars : individual (eta Carinae); stars : variables : other; X-rays : stars ID LONG-PERIOD BINARY; MILLIMETER EMISSION; VARIABILITY AB We solve the Rossi X-Ray Timing Explorer X-ray light curve of the extremely luminous and massive star eta Carinae with a colliding-wind emission model to refine the ground-based orbital elements. The sharp decline to X-ray minimum at the end of 1997 fixes the date of the last periastron passage at 1997.95 +/- 0.05, not 1998.13 as derived from ground-based radial velocities. This helps resolve a discrepancy between the ground-based radial velocities and spatially resolved velocity measures obtained by Space Telescope Imaging Spectograph (STIS). The X-ray data are consistent with a mass function f (M) approximate to 1.5, lower than the value f (M) approximate to 7.5 previously reported, so that the masses of eta Carinae and the companion are M-eta greater than or equal to 80 M. and M-c similar to 30 M-., respectively. In addition, the X-ray data suggest that the mass-loss rate from eta Carinae is generally less than 3 x 10(-4) M-. yr(-1), about a factor of 5 lower than that derived from some observations in other wave bands. We could not match the duration of the X-ray minimum with any standard colliding-wind model in which the wind is spherically symmetric and the mass-loss rate is constant. However, we show that we can match the variations around X-ray minimum if we include an increase of a factor of similar to 20 in the mass-loss rate from eta Carinae for approximately 80 days following periastron. If real, this excess in (M) over dot would be the first evidence of enhanced mass flow off the primary when the two stars are close (presumably driven by tidal interactions). Our interpretation of the X-ray data suggests that the ASCA and RXTE X-ray spectra near the X-ray minimum are significantly contaminated by unresolved hard emission (E greater than or equal to 2 keV) from some other nearby source, probably associated with scattering of the colliding-wind emission by circumstellar dust. Based on the X-ray fluxes, the distance to eta Carinae is 2300 pc with formal uncertainties of only similar to 10%. C1 Univ Space Res Assoc, Seabrook, MD 20706 USA. NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Lab Astron & Space Phys, Natl Res Council, 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 28 TC 103 Z9 103 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 FEB 1 PY 2001 VL 547 IS 2 BP 1034 EP 1039 DI 10.1086/318416 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397ZF UT WOS:000166728300044 ER PT J AU Boden, AF Lane, BF AF Boden, AF Lane, BF TI A preliminary visual orbit of BY Draconis SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : spectroscopic; binaries : visual; stars : flare; stars : individual (BY Draconis); techniques : interferometric ID PALOMAR TESTBED INTERFEROMETER; ROTATIONAL AXES; BINARY-SYSTEMS; MAIN-SEQUENCE; STARS AB We report on the preliminary determination of the visual orbit of the double-lined spectroscopic binary system BY Draconis with data obtained by the Palomar Testbed Interferometer in 1999. BY Dra is a nearly equal-mass double-lined binary system whose spectroscopic orbit is well known. We have estimated the visual orbit of BY Dra from our interferometric visibility data fit both separately and in conjunction with archival radial velocity data. Our BY Dra orbit is in good agreement with the spectroscopic results. Due to the orbit's face-on orientation, the physical parameters implied by a combined fit to our visibility data and radial velocity data do not yet result in precise component masses and a system distance, but with continued interferometric monitoring we hope to improve the mass estimates to better than 10% determinations. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. RP Boden, AF (reprint author), CALTECH, Ctr Infrared Proc & Anal, 770 S Wilson Ave, Pasadena, CA 91125 USA. NR 19 TC 16 Z9 16 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 FEB 1 PY 2001 VL 547 IS 2 BP 1071 EP 1076 DI 10.1086/318394 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397ZF UT WOS:000166728300047 ER PT J AU Chiang, EI Joung, MK Creech-Eakman, MJ Qi, C Kessler, JE Blake, GA van Dishoeck, EF AF Chiang, EI Joung, MK Creech-Eakman, MJ Qi, C Kessler, JE Blake, GA van Dishoeck, EF TI Spectral energy distributions of passive T Tauri and Herbig Ae disks: Grain mineralogy, parameter dependences, and comparison with Infrared Space Observatory LWS observations SO ASTROPHYSICAL JOURNAL LA English DT Article DE accretion, accretion disks; circumstellar matter; radiative transfer; stars : individual (MWC 480, HD 36112, CQ Tauri, LkCa 15, AA Tauri); stars : pre-main-sequence ID INTERSTELLAR SILICATE MINERALOGY; ACCRETION DISKS; CIRCUMSTELLAR DISKS; YOUNG OBJECTS; VERTICAL STRUCTURE; OPTICAL-CONSTANTS; STARS; DUST; IRRADIATION; CONTINUUM AB We improve upon the radiative, hydrostatic equilibrium models of passive circumstellar disks constructed by Chiang & Goldreich. New features include (1) an account for a range of particle sizes, (2) employment of laboratory-based optical constants of representative grain materials, and (3) numerical solution of the equations of radiative and hydrostatic equilibrium within the original two-layer (disk surface plus disk interior) approximation. We systematically explore how the spectral energy distribution (SED) of a face-on disk depends on grain size distributions, disk geometries and surface densities, and stellar photospheric temperatures. Observed SEDs of three Herbig Ae and two T Tauri stars, including spectra from the Long Wavelength Spectrometer (LWS) aboard the Infrared Space Observatory (ISO), are fitted with our models. Silicate emission bands from optically thin, superheated disk surface layers appear in nearly all systems. Water ice emission bands appear in LWS spectra of two of the coolest stars. Infrared excesses in several sources are consistent with significant vertical settling of photospheric grains. While this work furnishes further evidence that passive reprocessing of starlight by flared disks adequately explains the origin of infrared-to-millimeter wavelength excesses of young stars, we emphasize by explicit calculations how the SED alone does not provide sufficient information to constrain particle sizes and disk masses uniquely. C1 Inst Adv Study, Sch Nat Sci, Princeton, NJ 08540 USA. CALTECH 130 33, Pasadena, CA 91125 USA. Columbia Univ, Dept Astron, New York, NY 10027 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. CALTECH 150 21, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Div Chem & Chem Engn, Pasadena, CA 91125 USA. Sterrewacht Leiden, NL-2300 RA Leiden, Netherlands. RP Chiang, EI (reprint author), Inst Adv Study, Sch Nat Sci, Einstein Dr, Princeton, NJ 08540 USA. NR 38 TC 216 Z9 217 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 FEB 1 PY 2001 VL 547 IS 2 BP 1077 EP 1089 DI 10.1086/318427 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397ZF UT WOS:000166728300048 ER PT J AU Falconer, DA Davila, JM AF Falconer, DA Davila, JM TI Huge coronal structure and heating constraints determined from SERTS observations SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : UV radiation ID ELEMENTAL ABUNDANCES; ACTIVE-REGION; SOLAR CORONA; TEMPERATURE; EMISSION; DENSITY; LOOPS; EIT AB Intensities of the extreme-ultraviolet (EUV) spectral lines were measured as a function of radius off the solar limb by two flights of the Goddard's Solar Extreme-Ultraviolet Rocket Telescope and Spectrograph (SERTS) for three quiet-Sun regions. Density scale heights were determined for the different spectral lines. Limits on the filling factor were determined. In the one case where an upper limit was determined it was much less than unity. Coronal heating above 1.15 solar radii is required for all three regions studied. For reasonable filling factors, local heating is needed. C1 Univ Alabama, Huntsville, AL 35899 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. RP Falconer, DA (reprint author), NASA, George C Marshall Space Flight Ctr, SD 50, Huntsville, AL 35812 USA. NR 21 TC 3 Z9 3 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 FEB 1 PY 2001 VL 547 IS 2 BP 1109 EP 1115 DI 10.1086/318385 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397ZF UT WOS:000166728300051 ER PT J AU Lanza, AF Spadaro, D Lanzafame, AC Antiochos, SK MacNeice, PJ Spicer, DS O'Mullane, MG AF Lanza, AF Spadaro, D Lanzafame, AC Antiochos, SK MacNeice, PJ Spicer, DS O'Mullane, MG TI Extreme-ultraviolet transition-region line emission during the dynamic formation of prominence condensations SO ASTROPHYSICAL JOURNAL LA English DT Article DE Sun : corona; Sun : prominences; Sun : UV radiation ID NONEQUILIBRIUM IONIZATION; SOLAR PROMINENCES; CORONAL LOOPS; QUIESCENT PROMINENCES; FINE-STRUCTURE; MODEL AB We calculated the emission expected in EUV transition-region lines during the process of dynamic formation of prominence condensations in coronal loops, as predicted by the thermal nonequilibrium model of Antiochos et al. We selected some lines emitted by ions of carbon and oxygen because they are among the most intense and representative in the temperature range corresponding to the solar transition region. We present and discuss the principal characteristics of the line intensities and profiles synthesized from the hydrodynamic model at different times during the loop evolution. The ionization balance is computed in detail and the deviations from the ionization equilibrium caused by plasma flows and variations of temperature and density are accounted for. The atomic physics is treated using the latest atomic coefficients and the collisional-radiative theory approach. The synthesized carbon and oxygen lines exhibit a behavior significantly dependent on the variations of the plasma parameters inside the magnetic flux tube and therefore are suitable observational signatures of the processes giving rise to prominence condensations. In particular, a sizeable increase of line intensity as well as small blueshifts are expected from the loop footpoints during the first part of the evaporation phase that fills the loop with the material which subsequently condenses into the prominence. Once the condensation appears, line intensities decrease in the footpoints and simultaneously increase at the transition regions between the cool plasma of the condensation and the coronal portion of the loop. Line shifts are quite small in our symmetric model, and during most of the condensation's lifetime, the nonthermal widths are relatively small. These results can be compared with detailed ultraviolet observations of filament/prominence regions obtained by recent space missions in order to test the model proposed for the formation of solar prominences. C1 Osserv Astrofis Catania, I-95125 Catania, Italy. Univ Catania, Dipartimento Fis & Astron, I-95125 Catania, Italy. USN, Res Lab, EO Hulburt Ctr Space Res, Washington, DC 20375 USA. NASA, Goddard Space Flight Ctr, Ctr Computat Sci, Greenbelt, MD 20771 USA. Univ Strathclyde, Glasgow G4 0NG, Lanark, Scotland. RP Osserv Astrofis Catania, Via Santa Sofia 78, I-95125 Catania, Italy. EM nla@sunct.ct.astro.it; dsp@sunct.ct.astro.it; acl@sunct.ct.astro.it; antiochos@nrl.navy.mil; martin.omullane@jet.uk RI MacNeice, Peter/F-5587-2012; Antiochos, Spiro/D-4668-2012; Lanzafame, Alessandro/A-1129-2012 OI Antiochos, Spiro/0000-0003-0176-4312; Lanzafame, Alessandro/0000-0002-2697-3607 NR 47 TC 12 Z9 12 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 FEB 1 PY 2001 VL 547 IS 2 BP 1116 EP 1129 DI 10.1086/318410 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397ZF UT WOS:000166728300052 ER PT J AU Ofman, L Vinas, A Gary, SP AF Ofman, L Vinas, A Gary, SP TI Constraints on the O+5 anisotropy in the solar corona SO ASTROPHYSICAL JOURNAL LA English DT Article DE solar wind; Sun : corona; Sun : magnetic fields; waves ID WIND; TEMPERATURE; INSTABILITY; SIMULATION; VELOCITY; MODELS; WAVES AB Velocity distributions of O+5 ions derived from Ultraviolet Coronagraph Spectrometer (UVCS) observations in coronal holes indicate that the O+5 ions are highly anisotropic (T-perpendicular toi/T-parallel toi approximate to 30-300 at 3.5 R-.). The observations provide empirical values for the electron density and the ion temperatures. It is well known that the electromagnetic ion cyclotron instability is driven by temperature anisotropy. The instability leads to the rapid decrease of anisotropy and transfer of part of the kinetic energy of the particles into the magnetic field fluctuations. Here we use linear theory and hybrid simulations combined with the empirical values of the densities and the temperatures to investigate the ion cyclotron instability of the anisotropic minor ions in the coronal hole plasma. We find that an initial O+5 anisotropy of 50 decreases by an order of magnitude within similar to 300-900 proton cyclotron periods. Thus, the ion cyclotron instability constrains the anisotropy of O+5 ions that can be sustained in the solar corona without continuous perpendicular heating. C1 NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Raytheon ITSS, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Extraterr Phys Lab, Greenbelt, MD 20771 USA. Univ Calif Los Alamos Natl Lab, Los Alamos, NM 87545 USA. RP Ofman, L (reprint author), NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Raytheon ITSS, Mail Code 682, Greenbelt, MD 20771 USA. NR 21 TC 38 Z9 38 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 FEB 1 PY 2001 VL 547 IS 2 BP L175 EP L178 DI 10.1086/318900 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 398BA UT WOS:000166732800020 ER PT J AU Shuping, RY Chiar, JE Snow, TP Kerr, T AF Shuping, RY Chiar, JE Snow, TP Kerr, T TI Direct measurement of the CO depletion in the Elias 18 circumstellar disk SO ASTROPHYSICAL JOURNAL LA English DT Article DE infrared : ISM : lines and bands; ISM : abundances; ISM : clouds; ISM : molecules ID PROTOPLANETARY ACCRETION DISKS; TAURUS DARK CLOUD; YOUNG STARS; CHEMICAL-REACTIONS; HIGH-RESOLUTION; ROTATING-RING; GG TAURI; EVOLUTION; EMISSION; DUST AB In this Letter we present low-resolution 2.3 mum and high-resolution 4.6 mum spectra of Elias 18 (IRAS 04369+2539), a low-mass young stellar object (YSO) in the Taurus molecular cloud. The 2.3 mm spectrum shows CO band head emission (v = 2-0) indicating a circumstellar disk. The 4.6 mum spectrum shows very weak CO absorption in the lowest J levels. Comparing preexisting CO ice observations to our data indicates that there is at least 30 times less gas-phase CO than solid-state CO in the outer, cold (T < 20 K) regions of the disk. High depletions of CO in YSO disks have been inferred from millimeter-wave CO emission and detailed disk models, but Elias 18 is the first case for which both gas- and ice-phase data have been directly compared. C1 Univ Colorado, Ctr Astrophys & Space Astron, Boulder, CO 80309 USA. Univ Calif Los Angeles, Div Astron & Astrophys, Los Angeles, CA 90095 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Joint Astron Ctr, Hilo, HI 96720 USA. RP Shuping, RY (reprint author), Univ Colorado, Ctr Astrophys & Space Astron, Campus Box 391, Boulder, CO 80309 USA. EM shuping@astro.ucla.edu NR 30 TC 16 Z9 16 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 FEB 1 PY 2001 VL 547 IS 2 BP L161 EP L164 DI 10.1086/318899 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 398BA UT WOS:000166732800017 ER PT J AU Marcum, PM O'Connell, RW Fanelli, MN Cornett, RH Waller, WH Bohlin, RC Neff, SG Roberts, MS Smith, AM Cheng, KP Collins, NR Hennessy, GS Hill, JK Hill, RS Hintzen, P Landsman, WB Ohl, RG Parise, RA Smith, EP Freedman, WL Kuchinski, LE Madore, B Angione, R Palma, C Talbert, F Stecher, TP AF Marcum, PM O'Connell, RW Fanelli, MN Cornett, RH Waller, WH Bohlin, RC Neff, SG Roberts, MS Smith, AM Cheng, KP Collins, NR Hennessy, GS Hill, JK Hill, RS Hintzen, P Landsman, WB Ohl, RG Parise, RA Smith, EP Freedman, WL Kuchinski, LE Madore, B Angione, R Palma, C Talbert, F Stecher, TP TI An ultraviolet/optical atlas of bright galaxies SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Review DE galaxies : evolution; galaxies : fundamental parameters; galaxies : photometry; galaxies : structure; ultraviolet : galaxies ID HUBBLE-SPACE-TELESCOPE; H-II REGIONS; CCD SURFACE PHOTOMETRY; LARGE-MAGELLANIC-CLOUD; STAR-FORMATION RATE; HIGH-REDSHIFT GALAXIES; LARGE-SCALE STRUCTURE; IMAGING TELESCOPE; FAR-ULTRAVIOLET; SPIRAL GALAXIES AB We present wide-field imagery and photometry of 43 selected nearby galaxies of all morphological types at ultraviolet and optical wavelengths. The ultraviolet (UV) images, in two broad bands at 1500 and 2500 Angstrom, were obtained using the Ultraviolet Imaging Telescope (UIT) during the Astro-1 Spacelab mission. The UV images have similar to3 " resolution, and the comparison sets of ground-based CCD images (in one or more of B, V, R, and H alpha) have pixel scales and fields of view closely matching the UV frames. The atlas consists of multiband images and plots of UV/optical surface brightness and color profiles. Other associated parameters, such as integrated photometry and half-light radii, are tabulated. In an appendix, we discuss the sensitivity of different wavebands to a galaxy's star formation history in the form of " history weighting functions II and emphasize the importance of UV observations as probes of evolution during the past 10-1000 Myr. We find that UV galaxy morphologies are usually significantly different from visible band morphologies as a consequence of spatially inhomogeneous stellar populations. Differences are quite pronounced for systems in the middle range of Hubble types, Sa through Sc, but less so for ellipticals or late-type disks. Normal ellipticals and large spiral bulges are fainter and more compact in the UV. However, they typically exhibit smooth UV profiles with far-UV/optical color gradients which are larger than any at optical/IR wavelengths. The far-UV light in these cases is probably produced by extreme horizontal branch stars and their descendants in the dominant, low-mass, metal-rich population. The cool stars in the large bulges of Sa and Sb spirals fade in the UV while hot OB stars in their disks brighten, such that their Hubble classifications become significantly later. In the far-UV, early-type spirals often appear as peculiar, ringlike systems. In some spiral disks, UV-bright structures closely outline the spiral pattern; in others, the disks can be much more fragmented and chaotic than at optical wavelengths. Contributions by bright active galactic nuclei (AGNs) to the integrated UV light in our sample range from less than 10% to nearly 100%. A number of systems have unusual UV-bright structures in their inner disks, including rings, compact knots, and starburst nuclei, which could easily dominate the UV light in high-redshift analogs. A significant but variable fraction of the far-UV light in spiral disks is diffuse rather than closely concentrated to star-forming regions. Dust in normal spiral disks does not control UV morphologies, even in some highly inclined disk systems. The heaviest extinction is apparently confined to thin layers and the immediate vicinity of young H II complexes; the UV light emerges from thicker star distributions, regions evacuated of dust by photodestruction or winds, or by virtue of strong dust clumpiness. Only in cases where the dust layers are disturbed does dust appear to be a major factor in UV morphology. The UV-bright plume of M82 indicates that dust scattering of UV photons can be important in some cases. In a companion paper, we discuss far-UV data from the Astro-2 mission and optical comparisons for another 35 galaxies, emphasizing face-on spirals. C1 Texas Christian Univ, Dept Phys & Astron, Ft Worth, TX 76129 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. Univ N Texas, Dept Phys, Denton, TX 76203 USA. NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA. Tufts Univ, Dept Phys & Astron, Medford, MA 02155 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92634 USA. USN Observ, Washington, DC 20392 USA. Calif State Univ Long Beach, Dept Phys & Astron, Long Beach, CA 90840 USA. NASA, Goddard Space Flight Ctr, Comp Sci Corp, Greenbelt, MD 20771 USA. Carnegie Inst Washington Observ, Pasadena, CA 91101 USA. CALTECH, IPAC, Pasadena, CA 91125 USA. San Diego State Univ, Dept Astron, San Diego, CA 92182 USA. RP Texas Christian Univ, Dept Phys & Astron, Box 298840, Ft Worth, TX 76129 USA. EM p.marcum@tcu.edu; rwo@virginia.edu; fanelli@unt.edu NR 187 TC 66 Z9 66 U1 0 U2 3 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 FEB PY 2001 VL 132 IS 2 BP 129 EP 198 DI 10.1086/318953 PN 1 PG 70 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 402KP UT WOS:000166986400001 ER PT J AU Schmitt, HR Ulvestad, JS Antonucci, RRJ Kinney, AL AF Schmitt, HR Ulvestad, JS Antonucci, RRJ Kinney, AL TI Jet directions in Seyfert galaxies: Radio continuum imaging data SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE galaxies : active; galaxies : jets; galaxies : nuclei; galaxies : Seyfert; galaxies : structure; radio continuum : galaxies ID POINT-SOURCE CATALOG; WARM IRAS SOURCES; NARROW-LINE REGION; LIMITED SAMPLE; 2 GALAXIES; EMISSION; ACCRETION; DISKS; SPECTROSCOPY; MCG-8-11-11 AB We present the results of VLA A-array 8.46 GHz continuum imaging of 55 Seyfert galaxies (19 Seyfert 1's and 36 Seyfert 2's). These galaxies are part of a larger sample of 88 Seyfert galaxies, selected from mostly isotropic properties, the flux at 60 mum, and warm infrared 25-60 mum colors. These images are used to study the structure of the radio continuum emission of these galaxies and their position angles, in the case of extended sources. These data, combined with information from broadband B and I observations, have been used to study the orientation of radio jets relative to the plane of their host galaxies (Kinney et al.). C1 Space Telescope Sci Inst, Baltimore, MD 21218 USA. Natl Radio Astron Observ, Socorro, NM 87801 USA. Univ Calif Santa Barbara, Dept Phys, Santa Barbara, CA 93106 USA. NASA Headquarters, Washington, DC 20546 USA. RP Schmitt, HR (reprint author), Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA. NR 46 TC 49 Z9 49 U1 0 U2 1 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 FEB PY 2001 VL 132 IS 2 BP 199 EP 209 DI 10.1086/318957 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 402KP UT WOS:000166986400002 ER PT J AU Lee, SMC Bishop, PA Schneider, SM Greenisen, MC AF Lee, SMC Bishop, PA Schneider, SM Greenisen, MC TI Simulated shuttle egress: Comparison of two space shuttle protective garments SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article DE Launch and Entry Suit; advanced crew escape suit; carbon dioxide; spaceflight; human performance; anti-gravity suits; G-suits ID PERFORMANCE AB Background: In a previous study from our laboratory, we observed carbon dioxide (CO,) accumulation in the helmet of the NASA Launch and Entry Suit (LES) during a simulated emergency egress from the Space Shuttle. Of 12 subjects, 8 were unable to complete the egress simulation with a G-suit inflation pressure of 1.5 psi. The purpose of this report was to compare CO, accumulation and egress walking time in the new Advanced Crew Escape Suit (ACES) with that in the LES. Methods: Four male subjects who previously were unable to complete the egress in the LES performed a simulated egress while wearing the AGES with the C-suit inflated to 1.5 psi. The egress simulation consisted of 6 min of seated rest, 2 min of standing, and 5 min of walking on a treadmill at 1.56 m . s(-1) (3.5 mph) and 0% grade. The helmet visor was closed with the subjects receiving 100% oxygen throughout the simulation. Inspired CO, and walking time were measured. Results: The rate of CO, accumulation was significantly less (ACES: 0.53 +/- 0.03, LES: 1.07 +/- 0.15 %CO2 . min(-1); p = 0.05) and walk time was greater in the AGES (ACES: 5.0 +/- 0.0, LES: 2.7 +/- 0.2 min; p = 0.002). Conclusions: Changes in the design of the AGES from the LES resulted in a decreased rate of CO, accumulation and an improved egress walking time compared with the LES. C1 NASA, Lyndon B Johnson Space Ctr, Exercise Physiol Lab, Houston, TX 77058 USA. Wyle Labs, Life Sci Syst & Serv Div, Houston, TX USA. Univ Alabama, Human Performance Lab, Tuscaloosa, AL USA. RP Greenisen, MC (reprint author), NASA, Lyndon B Johnson Space Ctr, Exercise Physiol Lab, Mail Code SD3, Houston, TX 77058 USA. NR 13 TC 4 Z9 4 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 FEB PY 2001 VL 72 IS 2 BP 110 EP 114 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA 398EJ UT WOS:000166743600003 PM 11211038 ER PT J AU DeFelice, T Cahalan, R AF DeFelice, T Cahalan, R TI Comments on "Landsat-7 reveals more than just surface features in remote areas of the globe" - Reply SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Editorial Material C1 Raytheon EROS Data Ctr, Sioux Falls, SD USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP DeFelice, T (reprint author), Raytheon EROS Data Ctr, Sioux Falls, SD USA. RI Cahalan, Robert/E-3462-2012 OI Cahalan, Robert/0000-0001-9724-1270 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 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD FEB PY 2001 VL 82 IS 2 BP 314 EP 314 DI 10.1175/1520-0477(2001)082<0314:REPLY>2.3.CO;2 PG 1 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 398EC UT WOS:000166742900007 ER PT J AU Fabrizio, MC Dorazio, RM Schram, ST AF Fabrizio, MC Dorazio, RM Schram, ST TI Dynamics of individual growth in a recovering population of lake trout (Salvelinus namaycush) SO CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES LA English DT Article ID NONLINEAR MODELS; RECAPTURE DATA; VARIABILITY; PARAMETERS; SUPERIOR AB In 1976, the Wisconsin Department of Natural Resources established a refuge for a nearly depleted population of lake trout (Salvelinus namaycush) at Gull Island Shoal, Lake Superior. The refuge was intended to reduce fishing mortality by protecting adult lake trout. We examined the growth dynamics of these lake trout during the period of recovery by comparing estimates of individual growth before and after the refuge was established. Our estimates are based on an annual mark-recapture survey conducted at the spawning area since 1969. We developed a model that allowed mean growth rates to differ among individuals of different sizes and that accommodated variation in growth rates of individuals of the same size. Likelihood ratio tests were used to determine if the mean growth increments of lake trout changed after the refuge was established. Our results suggest that growth of mature lake trout (particularly wild fish) decreased significantly in the postrefuge period. This decreased growth may have been associated with a reduction in food availability. We also observed reductions in growth as wild fish grew older and larger, which suggests that the growth of these fish may be adequately approximated by a von Bertalanffy growth model if it becomes possible to obtain accurate ages. C1 US Geol Survey, Great Lakes Sci Ctr, Ann Arbor, MI 48105 USA. US Geol Survey, Florida Caribbean Sci Ctr, Gainesville, FL 32601 USA. Wisconsin Dept Nat Resources, Bayfield, WI 54814 USA. RP Fabrizio, MC (reprint author), Natl Marine Fisheries Serv, James J Howard Marine Sci Lab, Highlands, NJ 07732 USA. OI Fabrizio, Mary/0000-0002-6115-5490 NR 40 TC 10 Z9 11 U1 0 U2 8 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA, ONTARIO K1A 0R6, CANADA SN 0706-652X J9 CAN J FISH AQUAT SCI JI Can. J. Fish. Aquat. Sci. PD FEB PY 2001 VL 58 IS 2 BP 262 EP 272 DI 10.1139/cjfas-58-2-262 PG 11 WC Fisheries; Marine & Freshwater Biology SC Fisheries; Marine & Freshwater Biology GA 399WR UT WOS:000166837700004 ER PT J AU Potter, C Bubier, J Crill, P Lafleur, P AF Potter, C Bubier, J Crill, P Lafleur, P TI Ecosystem modeling of methane and carbon dioxide fluxes for boreal forest sites SO CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE LA English DT Article ID NET PRIMARY PRODUCTION; ATMOSPHERE INTERACTIONS; TEMPORAL VARIABILITY; PEATLAND COMPLEX; SOLAR-RADIATION; CO2 EXCHANGE; EMISSIONS; SURFACE; TEMPERATURE; WETLANDS AB Predicted daily fluxes from an ecosystem model for water, carbon dioxide, and methane were compared with 1994 and 1996 Boreal Ecosystem-Atmosphere Study (BOREAS) field measurements at sites dominated by old black spruce (Picea mariana (Mill.) BSP) (OBS) and boreal fen vegetation near Thompson, Man. Model settings for simulating daily changes in water table depth (WTD) for both sites were designed to match observed water levels, including predictions for two microtopographic positions (hollow and hummock) within the fen study area. Water run-on to the soil profile from neighboring microtopographic units was calibrated on the basis of daily snowmelt and rainfall inputs to reproduce BOREAS site measurements for timing and magnitude of maximum daily WTD for the growing season. Model predictions for daily evapotranspiration rates closely track measured fluxes for stand water loss in patterns consistent with strong controls over latent heat fluxes by soil temperature during nongrowing season months and by variability in relative humidity and air temperature during the growing season. Predicted annual net primary production (NPP) for the OBS site was 158 g C.m(-2) during 1994 and 135 g C.m(-2) during 1996, with contributions of 75% from overstory canopy production and 25% from ground cover production. Annual NPP for the wetter fen site was 250 g C.m(-2) during 1994 and 270 g C.m(-2) during 1996. Predicted seasonal patterns for soil CO2 fluxes and net ecosystem production of carbon both match daily average estimates at the two sites. Model results for methane flux, which also closely match average measured flux levels of -0.5 mg CH4.m(-2). day(-1) for OBS and 2.8 mg CH4.m(-2). day(-1) for fen sites, suggest that spruce areas are net annual sinks of about -0.12 g CH4.m(-2), whereas fen areas generate net annual emissions on the order of 0.3-0.85 g CH4.m(-2), depending mainly on seasonal WTD and microtopographic position. Fen hollow areas are predicted to emit almost three times more methane during a given year than fen hummock areas. The validated model is structured for extrapolation to regional simulations of interannual trace gas fluxes over the entire North America boreal forest, with integration of satellite data to characterize properties of the land surface. C1 NASA, Ames Res Ctr, Ecosyst Sci & Technol Branch, Moffett Field, CA 94035 USA. Mt Holyoke Coll, S Hadley, MA 01075 USA. Univ New Hampshire, Durham, NH 03824 USA. Trent Univ, Peterborough, ON K9J 7B8, Canada. RP Potter, C (reprint author), NASA, Ames Res Ctr, Ecosyst Sci & Technol Branch, Moffett Field, CA 94035 USA. OI Crill, Patrick/0000-0003-1110-3059 NR 73 TC 37 Z9 38 U1 1 U2 14 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA, ONTARIO K1A 0R6, CANADA SN 0045-5067 J9 CAN J FOREST RES JI Can. J. For. Res.-Rev. Can. Rech. For. PD FEB PY 2001 VL 31 IS 2 BP 208 EP 223 DI 10.1139/cjfr-31-2-208 PG 16 WC Forestry SC Forestry GA 402KT UT WOS:000166986700003 ER PT J AU Noor, AK Birman, V AF Noor, AK Birman, V TI Special issue - Selected Papers from the Special Symposium Honouring the 70th birthdays of Professors Charlie Bert and Jack Vinson SO COMPOSITE STRUCTURES LA English DT Editorial Material C1 Univ Virginia, NASA, Langley Res Ctr, Ctr Adv Computat Tech, Hampton, VA 23681 USA. Univ Missouri, Engn Educ Ctr, St Louis, MO 63121 USA. RP Noor, AK (reprint author), Univ Virginia, NASA, Langley Res Ctr, Ctr Adv Computat Tech, Mail Stop 201, Hampton, VA 23681 USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0263-8223 J9 COMPOS STRUCT JI Compos. Struct. PD FEB PY 2001 VL 51 IS 2 BP 127 EP 128 DI 10.1016/S0263-8223(00)00154-9 PG 2 WC Materials Science, Composites SC Materials Science GA 402WL UT WOS:000167011100001 ER PT J AU Noor, AK Starnes, JH Peters, JM AF Noor, AK Starnes, JH Peters, JM TI Uncertainty analysis of stiffened composite panels SO COMPOSITE STRUCTURES LA English DT Article DE composite panels; cylindrical panels; fuzzy sets; stiffeners; nonlinear analysis; uncertainities ID REDUCED BASIS TECHNIQUE AB A study is made of the variability in the nonlinear response of three stiffened composite panels associated with variations in their geometric and material parameters. The three panels have a cylindrical skin with either four or five T-shaped stiffeners. Two of the panels have a notch and the third panel has a circular cutout. Hierarchical sensitivity analysis is used to identify the major parameters at the micro-mechanical, layer, laminate and sub-component levels. The major parameters are then taken to be fuzzy parameters, and a fuzzy set analysis is used to determine the range of variation of the response associated with pre-selected variations in the major parameters. Published by Elsevier Science Ltd. C1 Univ Virginia, NASA, Langley Res Ctr, Ctr Adv Computat Technol, Hampton, VA 23681 USA. RP Noor, AK (reprint author), Univ Virginia, NASA, Langley Res Ctr, Ctr Adv Computat Technol, MS-201, Hampton, VA 23681 USA. NR 23 TC 13 Z9 13 U1 0 U2 3 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0263-8223 J9 COMPOS STRUCT JI Compos. Struct. PD FEB PY 2001 VL 51 IS 2 BP 139 EP 158 DI 10.1016/S0263-8223(00)00143-4 PG 20 WC Materials Science, Composites SC Materials Science GA 402WL UT WOS:000167011100003 ER PT J AU Chamis, CC Minnetyan, L AF Chamis, CC Minnetyan, L TI Defect/damage tolerance of pressurized fiber composite shells SO COMPOSITE STRUCTURES LA English DT Article DE composites; composite structures; computational simulation; damage; degradation; durability; fracture; laminates; pressure vessels; shells; structural degradation ID PROGRESSIVE FRACTURE AB Defect/damage tolerance and fracture of pressurized graphite/epoxy thin composite shells are evaluated via computational simulation. An integrated computer code that scales up constituent micromechanics level material properties to the structure level and accounts for all possible failure modes is used for the simulation of composite degradation under loading. Damage initiation, growth, accumulation, and propagation to fracture are included in the simulation. Design implications with regard to defect and damage tolerance of thin-walled composite cylindrical shells are examined. A procedure is outlined regarding the use of this type of information for setting quality acceptance criteria, design allowables, damage tolerance, and retirement-for-cause criteria. Illustrative examples are presented for cylindrical and hemispherical shells. Results show that defects have a significant effect on the burst pressure. Published by Elsevier Science Ltd. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Clarkson Univ, Potsdam, NY 13699 USA. RP Chamis, CC (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 17 TC 4 Z9 4 U1 0 U2 5 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0263-8223 J9 COMPOS STRUCT JI Compos. Struct. PD FEB PY 2001 VL 51 IS 2 BP 159 EP 168 DI 10.1016/S0263-8223(00)00141-0 PG 10 WC Materials Science, Composites SC Materials Science GA 402WL UT WOS:000167011100004 ER PT J AU Carlson, JR Duquesne, N Rumsey, CL Gatski, TB AF Carlson, JR Duquesne, N Rumsey, CL Gatski, TB TI Computation of turbulent wake flows in variable pressure gradient SO COMPUTERS & FLUIDS LA English DT Article ID HIGH-LIFT FLOWS; MODELS AB Transport aircraft performance is strongly influenced by the effectiveness of high-lift systems. Developing wakes generated by the airfoil elements are subjected to strong pressure gradients and can thicken very rapidly, limiting maximum lift. This paper focuses on the effects of various pressure gradients on developing symmetric wakes and on the ability of a linear eddy viscosity model and a nonlinear explicit algebraic stress model to accurately predict their downstream evolution. To reduce the uncertainties arising from numerical issues when assessing the performance of turbulence models, three different numerical codes with the same turbulence models are used. Results are compared to available experimental data to assess the accuracy of the computational results. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 NASA, Subson Aerodynam Branch, Langley Res Ctr, Hampton, VA 23681 USA. Royal Inst Technol, KTH, Dept Aeronaut, SE-10044 Stockholm, Sweden. NASA, Computat Modeling & Simulat Branch, Langley Res Ctr, Hampton, VA 23681 USA. RP Carlson, JR (reprint author), NASA, Subson Aerodynam Branch, Langley Res Ctr, Mail Stop 286, Hampton, VA 23681 USA. NR 23 TC 10 Z9 11 U1 0 U2 0 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 FEB PY 2001 VL 30 IS 2 BP 161 EP 187 DI 10.1016/S0045-7930(00)00007-4 PG 27 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA 393KR UT WOS:000166468200002 ER PT J AU Brodeur, RD AF Brodeur, RD TI Habitat-specific distribution of Pacific ocean perch (Sebastes alutus) in Pribilof Canyon, Bering Sea SO CONTINENTAL SHELF RESEARCH LA English DT Article DE habitat; acoustics; demersal fishes; zooplankton; Bering Sea; Pribilof Canyon ID SUBMARINE CANYONS; DEEP-SEA; CONTINENTAL-SHELF; ROCKFISH SEBASTES; VANCOUVER-ISLAND; NEW-ENGLAND; SLOPE; ZOOPLANKTON; EUPHAUSIIDS; ALASKA AB Shelf edge canyons are well-known sites of enhanced biomass due to on-shore transport and concentration of zooplankton along their axes, both of which contribute to the high densities of nekton frequently found in these canyons, Using a combination of acoustics, trawling, and in situ observations with a remotely operated vehicle (ROV), the distribution of pelagic and demersal biota within Pribilof Canyon in the Bering Sea was examined in September of 1995 and 1997. Near-bottom acoustic scattering patterns in the 38 kHz data showed high concentrations of biomass beginning around the 180 m bottom depth contour and continuing to about 320 m, which were presumed to be adult fish based on their target strength distributions. The 120 kHz data also showed very strong scattering in the water column between 150 and 175 m, which was absent from the 38 kHz data, and therefore attributed mainly to zooplankton. The dominant taxa collected in bottom trawls and mid-water plankton tows were adult rockfishes (Pacific ocean perch, Sebastes alutus) and euphausiids (Thysanoessa spp.), respectively. In situ videos revealed dense aggregations of these rockfishes inhabiting a "forest" of attached sea whips, Halipteris willemoesi, during night deployments of the ROV, while areas with damaged sea whips had far fewer rockfish, and areas without this biotic habitat structure had no rockfish, During the day, the rockfishes were seen above the "forest", where they were apparently feeding on dense swarms of euphausiids. it appears that these rockfish utilize this predictable and abundant food resource in the canyon during the day and are associated with the sea whip habitat at night during periods of inactivity. More research is needed on these slow-growing biotic habitats and how fishing activities in the Bering Sea and elsewhere may impact these habitats. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Natl Marine Fisheries Serv, Alaska Fisheries Sci Ctr, Seattle, WA 98115 USA. RP Brodeur, RD (reprint author), Natl Marine Fisheries Serv, NW Fisheries Sci Ctr, Hatfield Marine Sci Ctr, Newport, OR 97365 USA. NR 56 TC 66 Z9 66 U1 0 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0278-4343 J9 CONT SHELF RES JI Cont. Shelf Res. PD FEB PY 2001 VL 21 IS 3 BP 207 EP 224 DI 10.1016/S0278-4343(00)00083-2 PG 18 WC Oceanography SC Oceanography GA 400NX UT WOS:000166879200001 ER PT J AU Ott, CM Day, DF Koenig, DW Pierson, DL AF Ott, CM Day, DF Koenig, DW Pierson, DL TI The release of alginate lyase from growing Pseudomonas syringae pathovar phaseolicola SO CURRENT MICROBIOLOGY LA English DT Article ID EXOPOLYSACCHARIDE ALGINATE; SYRINGOMYCIN PRODUCTION; PV SYRINGAE; AERUGINOSA; GENE; POLYSACCHARIDE; SPECIFICITY; PLANT AB Pseudomonas syringae pathovar phaseolicola, which produces alginate during stationary growth phase. displayed elevated extracellular alginate lyase activity during both mid-exponential and late-stationary growth phases of batch growth. Intracellular activity remained below 22% of the total activity during exponential growth, suggesting that alginate lyase has an extracellular function for this organism. Extracellular enzyme activity in continuous cultures, grown in either nutrient broth or glucose-simple salts medium, peaked at 60% of the washout rate, although nutrient broth-grown cultures displayed more than twice the activity per gram of cell mass. These results imply that growth rate, nutritional composition, or both initiate a release of alginate lyase from viable P. syringae pv. phaseolicola, which could modify its entrapping biofilm. C1 Louisiana State Univ, Louisiana Agr Expt Stn, Audubon Suger Inst, Baton Rouge, LA 70803 USA. Krug Life Sci, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Ott, CM (reprint author), EASI Wyle Labs, 1290 Hercules Dr,Suite 120, Houston, TX 77058 USA. NR 20 TC 13 Z9 14 U1 1 U2 3 PU SPRINGER-VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 USA SN 0343-8651 J9 CURR MICROBIOL JI Curr. Microbiol. PD FEB PY 2001 VL 42 IS 2 BP 78 EP 81 DI 10.1007/s002840010182 PG 4 WC Microbiology SC Microbiology GA 392PD UT WOS:000166419100002 PM 11136126 ER PT J AU Burgman, MA Breininger, DR Duncan, BW Ferson, S AF Burgman, MA Breininger, DR Duncan, BW Ferson, S TI Setting reliability bounds on habitat suitability indices SO ECOLOGICAL APPLICATIONS LA English DT Article DE Florida Scrub-Jay; fuzzy numbers; habitat suitability; HSI; uncertainty ID FLORIDA SCRUB-JAY; DEMOGRAPHIC SUCCESS; DISTRIBUTIONS; SELECTION; EXAMPLE; QUALITY AB We expressed quantitative and qualitative uncertainties in suitability index functions as triangular distributions and used the mechanics of fuzzy numbers to solve for the distribution of uncertainty around the habitat suitability indices derived from them. We applied this approach to a habitat model for the Florida Scrub-Jay. The results demonstrate that priorities and decisions associated with management and assessment of ecological systems may be influenced by an explicit consideration of the reliability of the indices. C1 Univ Melbourne, Sch Bot, Parkville, Vic 3052, Australia. NASA, Dynamac Corp, Biomed Operat Off, Kennedy Space Ctr, FL 32899 USA. Appl Biomath, Setauket, NY 11733 USA. RP Burgman, MA (reprint author), Univ Melbourne, Sch Bot, Parkville, Vic 3052, Australia. NR 42 TC 62 Z9 67 U1 2 U2 16 PU ECOLOGICAL SOC AMER PI WASHINGTON PA 1707 H ST NW, STE 400, WASHINGTON, DC 20006-3915 USA SN 1051-0761 J9 ECOL APPL JI Ecol. Appl. PD FEB PY 2001 VL 11 IS 1 BP 70 EP 78 DI 10.2307/3061056 PG 9 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA 398GT UT WOS:000166749100006 ER PT J AU Ray, RD Eanes, RJ Lemoine, FG AF Ray, RD Eanes, RJ Lemoine, FG TI Constraints on energy dissipation in the Earth's body tide from satellite tracking and altimetry SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE Earth tides; Love number; ocean tides; Q; tides ID GLOBAL OCEAN TIDES; GRAVITY-FIELD; ROTATION RATE; SOLID EARTH; TOPEX/POSEIDON; MODEL; STARLETTE; MANTLE; DEFORMATION; GEODYNAMICS AB The phase lag by which the Earth's body tide follows the tidal potential is estimated for the principal lunar semi-diurnal tide M-2. The estimate results from combining recent tidal solutions from satellite tracking data and from Topex/Poseidon satellite altimeter data. Each data type is sensitive to the body tide lag: gravitationally for the tracking solutions, geometrically for the altimetry. Allowance is made for the lunar atmospheric tide. For the tidal potential Love number k(2), we obtain a lag epsilon of 0.20 degrees +/- 0.05 degrees, implying an effective body tide Q of 280 and body tide energy dissipation of 110+/-25 GW. C1 NASA, Goddard Space Flight Ctr, Space Geodesy Branch, Greenbelt, MD 20771 USA. Univ Texas, Ctr Space Res, Austin, TX 78712 USA. RP NASA, Goddard Space Flight Ctr, Space Geodesy Branch, Greenbelt, MD 20771 USA. EM richard.ray@gsfc.nasa.gov RI Ray, Richard/D-1034-2012; Lemoine, Frank/D-1215-2013 NR 67 TC 45 Z9 46 U1 1 U2 9 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 FEB PY 2001 VL 144 IS 2 BP 471 EP 480 DI 10.1046/j.1365-246x.2001.00356.x PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 410HB UT WOS:000167433600020 ER PT J AU Lorenz, RD Lunine, JI Withers, PG McKay, CP AF Lorenz, RD Lunine, JI Withers, PG McKay, CP TI Titan, Mars and Earth: Entropy production by latitudinal heat transport SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BALANCE CLIMATE MODEL; CYCLE AB Temperature contrasts between warm tropics and cool high latitudes depends on how efficiently heat is transported by the atmosphere (and oceans) from the tropics. This heat transport is generally assumed to be proportional to atmospheric pressure, but we show with a simple model that this prediction fails by orders of magnitude for Mars and Titan. However, a basic principle, previously postulated for the Earth, does successfully predict the heat hows and zonal temperatures of Mars and Titan. The circulation predicted by this Maximum Entropy Production (MEP) principle is consistent with Titan's observed zonal structure and the winds and CO2 frost cycle on Mars. The principle makes powerful predictions where detailed information is lacking, such as on the early Earth and on possibly habitable extrasolar planets. C1 Univ Arizona, Dept Planetary Sci, Lunar & Planetary Lab, Tucson, AZ 85721 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Lorenz, RD (reprint author), Univ Arizona, Dept Planetary Sci, Lunar & Planetary Lab, Tucson, AZ 85721 USA. RI Withers, Paul/H-2241-2014; Lorenz, Ralph/B-8759-2016 OI Lorenz, Ralph/0000-0001-8528-4644 NR 18 TC 119 Z9 119 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 FEB 1 PY 2001 VL 28 IS 3 BP 415 EP 418 DI 10.1029/2000GL012336 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 395LK UT WOS:000166581700004 ER PT J AU Mayr, HG Wolff, CL Hartle, RE AF Mayr, HG Wolff, CL Hartle, RE TI Wave driven non-linear flow oscillator for the 22-year solar cycle SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DOPPLER-SPREAD PARAMETERIZATION; QUASI-BIENNIAL OSCILLATION; EQUATORIAL OSCILLATIONS; MIDDLE ATMOSPHERE; GRAVITY-WAVES; G-MODES; MOMENTUM DEPOSITION; SUN AB In the Earth's atmosphere, a zonal flow oscillation is observed with periods between 20 and 32 months, the Quasi Biennial Oscillation. This oscillation does not require an external time dependent source but is maintained by nonlinear wave momentum forcing. We propose that such a mechanism also drives long-period oscillations in planetary and stellar interiors, and we apply it here to generate a flow oscillation for the 22-year solar cycle. The oscillation would occur just below the convective envelope - in a region where gravity waves can propagate. We present results from a simplified analytical modal that incorporates Hines' gravity wave parameterization. Wave amplitudes <10 m/s can produce reversing zonal flows of 20 m/s that should be sufficient to generate a corresponding oscillation in the poloidal magnetic field. The low buoyancy frequency and associated increase in turbulence help produce the desired oscillation period of the flow and should help generate the currents for the reversing magnetic field. C1 Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Mayr, HG (reprint author), Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 21 TC 0 Z9 0 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 FEB 1 PY 2001 VL 28 IS 3 BP 463 EP 466 DI 10.1029/2000GL012223 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 395LK UT WOS:000166581700016 ER PT J AU Dlugokencky, EJ Walter, BP Masarie, KA Lang, PM Kasischke, ES AF Dlugokencky, EJ Walter, BP Masarie, KA Lang, PM Kasischke, ES TI Measurements of an anomalous global methane increase during 1998 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERIC METHANE; GROWTH-RATE; NORTHERN-HEMISPHERE; DRAMATIC DECREASE; CH4; EMISSIONS; PINATUBO; GAS AB Measurements of atmospheric methane from a globally distributed network of air sampling sites indicate that the globally averaged CH4 growth rate increased from an average of 3.9 ppb yr(-1) during 1995-1997 to 12.7 +/- 0.6 ppb in 1998. The global growth rate then decreased to 2.6 +/- 0.6 ppb during 1999, indicating that the large increase in 1998 was not a return to the larger growth rates observed during the late-1970s and early-1980s. The increased growth rate during 1998 corresponds to an increase in the imbalance between CH4 sources and sinks equal to similar to 24 Tg CH4, the largest perturbation observed in 16 years of measurements. We suggest that wetland and boreal biomass burning sources may have contributed to the anomaly. An adaptation of a global process-based model, which included soil-temperature and precipitation anomalies, was used to calculate emission anomalies of 11.6 Tg CH4 from wetlands north of 30 degreesN and 13 Tg CH4 for tropical wetlands during 1998 compared to average emissions calculated for 1982-1993. For 1999, calculated wetland emission anomalies were negative for high northern latitudes and the tropics, contributing to the low growth rate observed in 1999. Also 1998 was a severe fire year in boreal regions where similar to1.3 x 10(5) km(2) of forest and peat land burned releasing an estimated 5.7 Tg CH4. C1 NOAA, CMDL, Boulder, CO 80305 USA. Columbia Univ, NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Univ Maryland, Dept Geog, College Pk, MD 20742 USA. RP Dlugokencky, EJ (reprint author), NOAA, CMDL, 325 Broadway, Boulder, CO 80305 USA. NR 24 TC 123 Z9 126 U1 0 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 1 PY 2001 VL 28 IS 3 BP 499 EP 502 DI 10.1029/2000GL012119 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 395LK UT WOS:000166581700025 ER PT J AU Jiang, JH Wu, DL AF Jiang, JH Wu, DL TI UARS MLS observations of gravity waves associated with the Arctic winter stratospheric vortex SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VARIANCE AB Passive satellite microwave limb radiances were used to study interactions between gravity waves and stratospheric winds in mid- to high latitude winter. We found that the radiance variances depend significantly on the instrument line-of-sight (LOS) and the background wind. The radiance variances are outstanding at two viewing angles where the LOS is about 30 degrees or 90 degrees from the wind vector. Waves propagating in preferred directions likely cause the two optimal angles observed. The variances at the 90 degrees angle, located inside the polar vortex, seem produced by the gravity waves propagating nearly parallel to the wind direction. The variances at the 30 degrees angle, located near the edge of the vortex, are likely associated with perturbations propagating almost perpendicularly to the wind direction. The variance of both modes increases with the background wind speed, but saturation is observed for the waves inside the vortex as wind speed exceeds about 60m/s. Interestingly, we also found that the temperature co-located with the variance inside the vortex is warmer by 20K at background wind speeds >60m/s, which might be correlated with the wave breaking in the vortex. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Jiang, JH (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr,Mail Stop 183-701, Pasadena, CA 91109 USA. RI Wu, Dong/D-5375-2012 NR 11 TC 17 Z9 17 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 FEB 1 PY 2001 VL 28 IS 3 BP 527 EP 530 DI 10.1029/2000GL011800 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 395LK UT WOS:000166581700032 ER PT J AU Cabrol, NA Grin, EA AF Cabrol, NA Grin, EA TI The evolution of lacustrine environments on Mars: Is Mars only hydrologically dormant? SO ICARUS LA English DT Review DE Mars; surface; exobiology; climate ID PATHFINDER LANDING SITE; ORBITER LASER ALTIMETER; IMPACT CRATER LAKES; GROUND ICE; SEDIMENTARY DEPOSITS; CHAOTIC OBLIQUITY; OUTFLOW CHANNELS; CLIMATIC CHANGE; LIQUID WATER; STABILITY AB This study surveys the evolution of martian impact crater paleolakes through time by establishing their age, comparing their locations, and describing the formation of lacustrine sedimentary structures and features over time. We explore their meaning in terms of global climate changes, but also on local and regional scales. We observe a co-location between recent impact crater paleolakes and regions where GCM modeling shows that Mars is currently experiencing days above triple point and below boiling point of water. Some source areas show morphologies that could be consistent with ancient glacier features in the Argyre Basin/Darwin Crater region, in locations that are also consistent with GCM models of past snow precipitation on Mars. We propose that, at least for some paleolakes, our results are best explained by recent, and abundant, aqueous activity on Mars, with some meteorological contribution. These results are supported by other recent findings on martian meteorite ages, by the analysis of new MGS data showing recent volcanic and fluvial activity, and by climate modeling. They point toward the possibility that Mars currently is only hydrologically dormant and that there is a potential for hydrological activity to be generated again in the future following changes in the planet's orbital parameters. (C) 2001 Academic Press. C1 NASA, Ames Res Ctr, SETI Inst, Div Space Sci, Moffett Field, CA 94035 USA. RP Cabrol, NA (reprint author), NASA, Ames Res Ctr, SETI Inst, Div Space Sci, MS 245-3, Moffett Field, CA 94035 USA. EM ncabrol@mail.arc.nasa.gov NR 169 TC 102 Z9 104 U1 0 U2 7 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 FEB PY 2001 VL 149 IS 2 BP 291 EP 328 DI 10.1006/icar.2000.6530 PG 38 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407CA UT WOS:000167252800001 ER PT J AU Irwin, PGJ Weir, AL Taylor, FW Calcutt, SB Carlson, RW AF Irwin, PGJ Weir, AL Taylor, FW Calcutt, SB Carlson, RW TI The origin of belt/zone contrasts in the atmosphere of Jupiter and their correlation with 5-mu m opacity SO ICARUS LA English DT Article DE Jupiter; atmosphere; clouds ID LARGE PHASE ANGLES; CLOUD STRUCTURE; OPTICAL-CONSTANTS; JOVIAN ATMOSPHERE; VOYAGER IRIS; IMAGING DATA; GALILEO; SPECTRA; ICE; REGION AB The commonly held interpretation of the observed banded structure of the jovian atmosphere is that "zones" are regions of dense clouds and thus high reflectivity and low thermal emission, while "belts" are relatively cloud-free regions of low reflectivity but high thermal emission. However, it has not been possible with existing data to identify unambiguously which of a number of possible jovian cloud layers (J. S. Lewis 1969, Icarus 10, 365-378) is mainly responsible for these variations. New data from the Near Infrared Mapping Spectrometer (NIMS) aboard the Galileo spacecraft have been analyzed which have good spectral coverage at both near-IR and 5-mum wavelengths over wide areas. These new data provide compelling evidence that the main source of the near-IR reflectivity variability, observed to be anticorrelated with 5-mum brightness, is due to opacity changes of cloud layers lying at pressures between I and 2 bar, and not to variability of the higher altitude ammonia cloud, the other main likely candidate. However, whether this main variable cloud layer is composed of ammonium hydrosulfide, the upper levels of a deeper water ice cloud, or something else is unknown. We also find that most of the particles in the upper troposphere must be rather small, in order that their reflectivity drops rapidly with wavelength, but we deduce that there must also be a component of larger sized particles, probably composed of ammonia ice, to account for the correlation between the 5- and 45-mum emission observed by Voyager. However, although a significant opacity of large ammonia particles does provide a good fit to the observed cloud absorption feature near 3-mum, these particles introduce a number of unobserved features at other wavelengths; thus we conclude that their opacity must be small. (C) 2001 Academic Press. C1 Univ Oxford, Clarendon Lab, Oxford OX1 3PU, England. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Irwin, PGJ (reprint author), Univ Oxford, Clarendon Lab, Parks Rd, Oxford OX1 3PU, England. OI Calcutt, Simon/0000-0002-0102-3170; Irwin, Patrick/0000-0002-6772-384X NR 40 TC 36 Z9 36 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 FEB PY 2001 VL 149 IS 2 BP 397 EP 415 DI 10.1006/icar.2000.6542 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407CA UT WOS:000167252800008 ER PT J AU Sromovsky, LA Fry, PM Baines, KH Limaye, SS Orton, GS Dowling, TE AF Sromovsky, LA Fry, PM Baines, KH Limaye, SS Orton, GS Dowling, TE TI Coordinated 1996 HST and IRTF imaging of Neptune and Triton I. Observations, navigation, and differential deconvolution SO ICARUS LA English DT Article DE Neptune; Neptune; atmosphere; Triton; infrared observations; data reduction techniques ID ATMOSPHERIC STRUCTURE; URANUS; TITAN; SPECTROPHOTOMETRY; RESTORATION; IMAGES AB On 13-14 August 1996, we carried out the first coordinated contemporaneous imaging of Neptune, using the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 and the NASA Infrared Telescope Facility(IRTF) NSFCAM InSb camera to obtain high spatial resolution absolutely calibrated imagery at wavelengths from 0.2 to 2.5 mum. We used nine HST orbits to provide unique dynamical coverage of a single rotation of Neptune. During three orbits we obtained virtually simultaneous groundbased images. These data provide an extended range of wavelengths that sample the Rayleigh scattering regime, both strong and weak methane bands, and strong near-infrared hydrogen collision-induced opacity bands, from which strong constraints can be obtained on the properties of Neptune's cloud features. We developed very precise navigation techniques, which were required to achieve colocation of the observations from these different observatories. Technique advances include compensating for limb profile distortions by bright cloud features in HST images and dealing with a nearly invisible limb in the near-IR groundbased images. We achieved RMS center-finding accuracy of 0.003"-0.006" (0.05-0.1 pixels) for HST navigations. To obtain the subpixel navigation accuracy of the groundbased images, we determined NSFCAM pixel scale versus wavelength and as a function of location on the detector, establishing a distortion correction equation for NSFCAM imaging. This permitted use of a navigation method based on offsetting from Triton, with which we achieved IRTF center-finding accuracy of 0.02" (0.1 pixel) RMS, and 0.2-0.3 pixels absolute, We developed a novel differential deconvolution method for significantly reducing deconvolution artifacts within the planetary disk and improving convergence properties for planetary cloud features, resulting in by far the most detailed groundbased images of Neptune yet obtained without speckle imaging or adaptive optics. (C) 2001 Academic Press. C1 Univ Wisconsin, Ctr Space Sci & Engn, Madison, WI 53706 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Louisville, Comparat Planetol Lab, Louisville, KY 40292 USA. RP Sromovsky, LA (reprint author), Univ Wisconsin, Ctr Space Sci & Engn, 1225 W Dayton St, Madison, WI 53706 USA. RI Dowling, Timothy/J-4537-2013 OI Dowling, Timothy/0000-0002-7400-2274 NR 34 TC 15 Z9 15 U1 2 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 FEB PY 2001 VL 149 IS 2 BP 416 EP 434 DI 10.1006/icar.2000.6562 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407CA UT WOS:000167252800009 ER PT J AU Sromovsky, LA Fry, PM Baines, KH Dowling, TE AF Sromovsky, LA Fry, PM Baines, KH Dowling, TE TI Coordinated 1996 HST and IRTF imaging of Neptune and Triton II. Implications of disk-integrated photometry SO ICARUS LA English DT Article DE Neptune; Neptune; atmosphere; Triton; photometry ID SPECTRAL IRRADIANCE; INFRARED-SPECTRA; SOLAR-RADIATION; CLOUD STRUCTURE; JOVIAN PLANETS; SPECTROPHOTOMETRY; CALIBRATION; METHANE; TITAN; TEMPERATURE AB Near-IR groundbased observations coordinated with Wide Field Planetary Camera 2 (WFPC2) HST observations (Sromovsky et al. Icarus 149, 416-434, 459-488) provide new insights into the variations of Neptune and Triton over a variety of time scales. From 1996 WFPC2 imaging we find that a broad circumpolar nonaxisymmetric dark band dominates Neptune's lightcurve at 0.467 mum, while three discrete bright features dominate the lightcurve at longer wavelengths, with amplitudes of 0.5% at 0.467 mum and 22% at 0.89 mum, but of opposite phases. The 0.89-mum modulation in 1994, estimated at 39%, is close to the 50% modulation observed during the 1986 "outburst" documented by Hammel et al. (1992, Icarus 99, 363-367), suggesting that the unusual 1994 cloud morphology might also have been present in 1986. Lightcurve amplitudes in J-K bands, from August 1996 IRTF observations, are comparable to those observed in 1977 (D. P. Cruikshank 1978, Astrophys. J. Lett. 220, 57-59) but significantly larger than the 1981 amplitudes of M. J. S. Belton et al. (1981, Icarus 45, 263-273). The 1996 disk-integrated albedos of Neptune at H-K wavelengths are 2-7 times smaller than the 1977 values of U. Fink and S. Larson (1979, Astrophys. J. 233, 1021-1040), which can be explained with about 1/2-1/4 of the upper level cloud opacity being present in 1996. A simplified three-layer model of cloud structure applied to CCD wavelengths implies similar to7% reflectivity at 1.3 bars (at lambda = 0.55 mum, decreasing as lambda (-0.94)) and similar to1% at 100-150 mbars. To fit the WFPC2 observations and those of E. Karkoschka (1994, Icarus 111, 174-192), the putative H(2)S cloud between 3.8 and 7-9 bars must have a strong decrease in reflectivity between 0.5 and 0.7 mum, as previously determined by K. H. Baines and W. H. Smith (1990, Icarus 85, 65-108). To match our 1996 IRTF results, this cloud must have another substantial drop in reflectivity at near-IR wavelengths, to a level of 0-5%, corresponding to single-scattering albedos of similar to0-0.3. The model that fits our near-IR observations on 13 August 1996 can reproduce the magnitudes of the dramatic 1976 "outburst" (R. R. Joyce et al. 1977, Astrophys. J. 214, 657-662) by increasing the upper cloud fraction to 6% (from similar to1%) and lowering its effective pressure to similar to 90 mbars (from 151 mbars). Triton's disk-integrated albedo from HST imagery at 11 wavelengths from 0.25 to 0.9 mum are consistent with previous groundbased and Voyager measurements, thus providing no evidence for the albedo decrease suggested by Triton's recent warming (J. L. Elliot et al. 1998 Nature 393, 765-767). Triton's lightcurve inferred from 1994-1996 WFPC2 observations has about twice the amplitude inferred from 1989 Voyager models for the UV to long visible range (J. Hillier et al. 1991, J. Geophys. Res. 96, 19,211-19,215). (C) 2001 Academic Press. C1 Univ Wisconsin, Ctr Space Sci & Engn, Madison, WI 53706 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Univ Louisville, Comparat Planetol Lab, Louisville, KY 40292 USA. RP Sromovsky, LA (reprint author), Univ Wisconsin, Ctr Space Sci & Engn, 1225 W Dayton St, Madison, WI 53706 USA. EM larry.sromovsky@ssec.wisc.edu RI Dowling, Timothy/J-4537-2013 OI Dowling, Timothy/0000-0002-7400-2274 NR 64 TC 24 Z9 24 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2001 VL 149 IS 2 BP 435 EP 458 DI 10.1006/icar.2000.6563 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407CA UT WOS:000167252800010 ER PT J AU Sromovsky, LA Fry, PM Dowling, TE Baines, KH Limaye, SS AF Sromovsky, LA Fry, PM Dowling, TE Baines, KH Limaye, SS TI Coordinated 1996 HST and IRTF imaging of Neptune and Triton III. Neptune's atmospheric circulation and cloud structure SO ICARUS LA English DT Article DE Neptune; Neptune; atmosphere; atmospheres; dynamics ID INFRARED-ABSORPTION SPECTRA; DISK-INTEGRATED PHOTOMETRY; VOYAGER MEASUREMENTS; MOIST CONVECTION; METHANE-BAND; TEMPERATURES; WAVELENGTHS; PAIRS; ABUNDANCE; DYNAMICS AB The first coordinated multispectral imaging of Neptune and Triton, using both the Hubble Space Telescope and the NASA Infrared Telescope Facility in August 1996 (L. A. Sromovsky et al., 149, 416-434, 435-458), provides new insights into Neptune's atmospheric circulation and cloud structure. From our 1996 data we derived cloud-tracked winds for 18 features spanning latitudes from 61 degreesS to 38 degreesN, finding generally close agreement with the smoothed 1989 Voyager wind profile (Sromovsky et al. 1993, Icarus 105, 110-141), except for features associated with a northern Great Dark Spot (GDS), which moved with the spot rather than with the local mass how providing another example of GDS traveling companions. In addition to finding a GDS at similar to 32 degreesN, thought to be the same one first seen in 1994 near the same latitude (Hammel et al. 1995, Science 268, 1740-1742), we also found a new kind of GDS at similar to 15 degreesN, which is unusual because of its low latitude and lack of a bright companion. From blue images we determined that the dark cloud band near 60 degreesS latitude is significantly nonaxisymmetric, as was a similar band in 1989 Voyager images, both with a wavenumber-one zonal structure and a similar to5 degrees latitudinal variation. We also identified a persistent pattern of clouds at 45 degreesS, which exhibit strong variations in brightness on yearly time scales. Using HST archived observations, we determined cloud-tracked winds for June and November 1994 and September 1995, confirming and extending the 1995 result of Hammel and Lockwood (1997, Icarus 129, 466-481) that most winds agreed with the Voyager profile. A significant exception we found in November 1994 is the similar to 100 mis meridional motion within the transient structure identified as the "bright complex" by H. B. Hammel and G. W. Lockwood (1997, Icarus 129, 466-481). The integrated brightness of this group of GDS traveling companions is sufficient to produce a hemispheric brightness asymmetry of 0.36 mag (Sromovsky et al., 149, 435-458), comparable to the 0.44 mag associated with the 1987 "outburst" maximum (Hammel et al. 1992, Icarus 99, 363-367). We determined spectral differences in cloud bands using complete global mosaics of 1996 imagery. Colocation of features in HST and groundbased near-IR images enabled us to characterize spectral variations in discrete features from the visible to 2.4 mum, from which we estimated cloud heights for discrete bright features ranging from 60 to 230 mbars. We found the equatorial atmosphere that is free of bright clouds to be very dark beyond 0.7 mum, from which we derived new upper bounds of similar to0.2 and similar to0.1 at 1.27 and 1.6 mum, respectively, on the single-scattering albedo of the putative 3.8-bar H(2)S cloud. (C) 2001 Academic Press. C1 Univ Wisconsin, Ctr Space Sci & Engn, Madison, WI 53706 USA. Univ Louisville, Comparat Planetol Lab, Louisville, KY 40292 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Sromovsky, LA (reprint author), Univ Wisconsin, Ctr Space Sci & Engn, 1225 W Dayton St, Madison, WI 53706 USA. EM larry.sromovsky@ssec.wisc.edu RI Dowling, Timothy/J-4537-2013 OI Dowling, Timothy/0000-0002-7400-2274 NR 48 TC 41 Z9 41 U1 0 U2 2 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 J9 ICARUS JI Icarus PD FEB PY 2001 VL 149 IS 2 BP 459 EP 488 DI 10.1006/icar.2000.6564 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407CA UT WOS:000167252800011 ER PT J AU Sanchez-Lavega, A Orton, GS Morales, R Lecacheux, J Colas, F Fisher, B Fukumura-Sawada, P Golisch, W Griep, D Kaminski, C Baines, K Rages, K West, R AF Sanchez-Lavega, A Orton, GS Morales, R Lecacheux, J Colas, F Fisher, B Fukumura-Sawada, P Golisch, W Griep, D Kaminski, C Baines, K Rages, K West, R TI The merger of two giant anticyclones in the atmosphere of Jupiter SO ICARUS LA English DT Article DE Jupiter; atmosphere; atmospheric dynamics ID GREAT RED SPOT; CLOUD FEATURES; WHITE OVALS; VORTICES; DYNAMICS; SIMULATION; STABILITY; GENESIS; VORTEX; SYSTEM AB Two giant ovals in Jupiter's southern atmosphere, vortices of counterclockwise-rotating winds, merged in a 3-week period, starting in March 2000. One of the ovals called FA was more than 60 years old; the other called BE was the product of two 60-year-old ovals (BC and DE) that merged in 1998 (A, Sanchez-Lavega ef al. 1999, Icarus 142, 116-124). The merger took place when the ovals were southeast of the Great Red Spot and after the disappearance of a smaller clockwise-rotating oval midway between them. The interaction began when the high-altitude oval clouds showed counterclockwise rotation about each other, followed by coalescence and shrinking. The interaction in deeper clouds did not include mutual rotation, but there was evidence of complex cloud structure during the merger. (C) 2001 academic Press. C1 Univ Basque Country, ETS Ingenieros, Dept Fis Aplicada 1, Bilbao 48013, Spain. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Observ Paris, DESPA, F-92195 Meudon, France. Inst Mecan Celeste, F-75014 Paris, France. Univ Hawaii, Inst Astron, Honolulu, HI 96822 USA. Space Phys Res Inst, Sunnyvale, CA 94087 USA. RP Sanchez-Lavega, A (reprint author), Univ Basque Country, ETS Ingenieros, Dept Fis Aplicada 1, Alameda Urquijo S-N, Bilbao 48013, Spain. EM wupsalaa@bi.ehu.es OI Sanchez-Lavega, Agustin/0000-0001-7355-1522 NR 27 TC 31 Z9 31 U1 1 U2 3 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0019-1035 EI 1090-2643 J9 ICARUS JI Icarus PD FEB PY 2001 VL 149 IS 2 BP 491 EP 495 DI 10.1006/icar.2000.6548 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 407CA UT WOS:000167252800013 ER PT J AU Kerslake, TW Haraburda, FM Riehl, JP AF Kerslake, TW Haraburda, FM Riehl, JP TI Solar power system options for the radiation and technology demonstration spacecraft SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB The Radiation and Technology Demonstration (RTD) Mission has the primary objective of demonstrating high-power (10 kilowatts) electric thruster technologies in Earth orbit. This paper discusses the conceptual design of the RTD spacecraft photovoltaic (PV) power system and mission performance analyses. These power system studies assessed multiple options for PV arrays, battery technologies and bus voltage levels. To quantify performance attributes of these power system options, a dedicated Fortran code was developed to predict power system performance and estimate system mass. The low-thrust mission trajectory was analyzed and important Earth orbital environments were modeled. Baseline power system design options are recommended on the basis of performance, mass and risk/complexity. Important findings from parametric studies are discussed and the resulting impacts to the spacecraft design and cost. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Kerslake, TW (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 34 TC 1 Z9 1 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 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD FEB PY 2001 VL 16 IS 2 BP 9 EP 19 DI 10.1109/62.904239 PG 11 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA 403YT UT WOS:000167067200003 ER PT J AU Gawronski, W AF Gawronski, W TI Antenna control systems: From PI to H-infinity SO IEEE ANTENNAS AND PROPAGATION MAGAZINE LA English DT Article DE control systems; control engineering; antennas; pointing systems; reflector antennas; reflector antenna; mechanical factors; linear-quadratic-Gaussian control; H-infinity control AB This paper discusses the compensation of antenna-pointing errors following the recent analysis and retrofit of the NASA Deep Space Network antenna-control systems. The desired high-frequency communications with spacecraft (at Ka-band) require improved pointing precision over lower-frequency communications (at X-band). The quality of the antenna drives (hardware), the control algorithm (software), and the physical structure of the antenna (in terms of thermal deformations, gravity distortions, encoder mounting, and wind gusts) all influence pointing precision, and create the challenging task of remaining within the required pointing-error budget. Three control algorithms - PI (proportional-and-integral), LQG (linear-quadratic-Gaussian), and H-infinity - are discussed, and their basic properties, tracking precision, and limitations as applied to antenna tracking are addressed. The paper shows that the PI algorithm is simple and reliable, but its performance is limited. It also explains how significant improvements in tracking precision are achieved when implementing the LQG control algorithm or the H-infinity control algorithm. Still, pointing precision attributable to software modification is limited. It is pointed out that an additional increase of tracking precision requires concurrent improvements in the antenna drives. C1 CALTECH, Jet Prop Lab, Commun Ground Syst Sect, Pasadena, CA 91109 USA. RP Gawronski, W (reprint author), CALTECH, Jet Prop Lab, Commun Ground Syst Sect, 4800 Oak Grove Dr,MS 238-528, Pasadena, CA 91109 USA. EM wodek.k.gawronski@jpl.nasa.gov NR 8 TC 14 Z9 21 U1 0 U2 2 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 FEB PY 2001 VL 43 IS 1 BP 52 EP 60 DI 10.1109/74.920018 PG 9 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 417YG UT WOS:000167862600007 ER PT J AU Ponchak, GE Chun, D Yook, JG Katehi, LPB AF Ponchak, GE Chun, D Yook, JG Katehi, LPB TI Experimental verification of the use of metal filled via hole fences for crosstalk control of microstrip lines in LTCC packages SO IEEE TRANSACTIONS ON ADVANCED PACKAGING LA English DT Article DE coupling; crosstalk; microstrip; microwave transmission lines ID TECHNOLOGY AB Coupling between microstrip lines in dense RF packages is a common problem that degrades circuit performance. Prior three-dimensional-finite element method (S-D-FEM) electromagnetic simulations have shown that metal filled via hole fences between two adjacent microstrip lines actually increases coupling between the lines; however, if the top of the via posts are connected by a metal strip, coupling is reduced, In this paper, experimental verification of the 3-D-FEM simulations is demonstrated for commercially fabricated low temperature cofired ceramic (LTCC) packages. In addition, measured attenuation of microstrip lines surrounded by the shielding structures is presented and shows that shielding structures do not change the attenuation characteristics of the line. C1 NASA, Glenn Res Ctr, Elect Devices Technol Branch, Cleveland, OH 44135 USA. Univ Michigan, Dept Elect Engn & Comp Sci, Ann Arbor, MI 48109 USA. Kwang Ju Inst Sci & Technol, Dept Informat & Commun, Kwangju 500712, South Korea. RP Ponchak, GE (reprint author), NASA, Glenn Res Ctr, Elect Devices Technol Branch, Cleveland, OH 44135 USA. NR 20 TC 16 Z9 20 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1521-3323 J9 IEEE TRANS ADV PACK JI IEEE Trans. Adv. Packag. PD FEB PY 2001 VL 24 IS 1 BP 76 EP 80 DI 10.1109/6040.909628 PG 5 WC Engineering, Manufacturing; Engineering, Electrical & Electronic; Materials Science, Multidisciplinary SC Engineering; Materials Science GA 409DX UT WOS:000167370200011 ER PT J AU Pogorzelski, RJ AF Pogorzelski, RJ TI On the dynamics of two-dimensional array beam scanning via perimeter detuning of coupled oscillator arrays SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article DE beamsteering; coupling circuits; phased arrays; voltage-controlled oscillators AB Arrays of voltage-controlled oscillators coupled to nearest neighbors have been proposed as a means of controlling the aperture phase of one-dimensional (1-D) and two-dimensional (2-D) array antennas. It has been demonstrated, both theoretically and experimentally, that one may achieve linear distributions of phase across a linear array aperture by tuning the end oscillators of the array away from the ensemble frequency of a mutually injection-locked array of oscillators. These linear distributions result in steering of the radiated beam. It is demonstrated theoretically that one may achieve similar beamsteering in two dimensions by appropriately tuning the perimeter oscillators of a 2-D array. The analysis is based on a continuum representation of the phase in which a continuous function satisfying a partial differential equation of diffusion type passes through the phase of each oscillator as its independent variables pass through integer values indexing the oscillators. Solutions of the partial differential equation for the phase function exhibit the dynamic behavior of the array during the beamsteering transient. 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 6 TC 23 Z9 26 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 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD FEB PY 2001 VL 49 IS 2 BP 234 EP 242 DI 10.1109/8.914289 PG 9 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 417EN UT WOS:000167822600011 ER PT J AU Pogorzelski, RJ AF Pogorzelski, RJ TI Two-dimensional array beam scanning via externally and mutually injection-locked coupled oscillators SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Article DE beamsteering; coupling circuits; injection-locking phased arrays; voltage-controlled oscillators ID PHASED-ARRAYS; DYNAMICS AB The use of arrays of injection-locked voltage-controlled oscillators coupled to nearest neighbors has been proposed as a means of controlling the aperture phase of one and two-dimensional (2-D) phased-array antennas, It has been demonstrated both theoretically and experimentally that one may achieve linear distributions of phase across a linear array aperture by injection locking to an external oscillator the end oscillators of an arl ag of a mutually injection-locked oscillators, These linear distributions cause steering of the radiated beam, It is demonstrated theoretically here that one may achieve beamsteering in a similar manner in two dimensions by injecting appropriately phased signals into the perimeter oscillators of a 2-D array, The analysis is based on a continuum representation of the phase previously developed in the context of beamsteering via tuning of the perimeter oscillators. 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 11 TC 7 Z9 7 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD FEB PY 2001 VL 49 IS 2 BP 243 EP 249 DI 10.1109/8.914291 PG 7 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA 417EN UT WOS:000167822600012 ER PT J AU Lyapustin, AI AF Lyapustin, AI TI Three-dimensional effects in the remote sensing of surface albedo SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE atmospheric correction; surface albedo; three-dimensional (3-D) radiative transfer ID ATMOSPHERIC CORRECTION; SIMULATION; RADIATION; LAND AB Most of contemporary analysis of satellite data is based on the classical Chandrasekhar's formula for the mean radiance, which is valid only when the surface is infinite and uniform. Over an inhomogeneous surface, the measured radiance will also contain two variational terms describing the direct and diffuse atmospheric transmission of the solar radiation reflected from spatial variations of surface reflectance. Calculation of the diffuse transmission requires knowledge of the atmospheric point-spread function (PSF) or its Fourier transform (FT) optical transfer function (OTF), which is a solution of the three-dimensional (3-D) radiative transfer problem, Using a method of spherical harmonics, we have recently obtained a rigorous solution for a two-dimensional (2-D) problem, where surface albedo varies only in one of the coordinate axes. It allows us to precisely model radiance fields over arbitrarily nonhomogeneous Lambertian "striped" surfaces. The simplest surface of this type consists of a dark and a bright homogeneous half-planes, The radiance distribution for this surface model was well studied in the past at high sensor resolution in the nadir direction, In reality, land surface exhibits a broad range of spatial variations, and data available to the land remote sensing community have resolution from tens of meters to several kilometers, often at varying zenith view angles. A study of the 3-D effects in these realistic conditions and assessments of the accuracy of atmospheric corrections based on a one-dimensional (1-D) radiative transfer theory are the main objectives of this work, The conclusions of this study can be summarized as follows. 3-D effects are the major source of albedo errors at high spatial resolution. The errors incurred may be as high as 0.04-0.06 in the near-IR and 0.01-0.04 in the visible range of the spectrum. At a medium resolution of I km, these errors are relatively small (0.005-0.02) and are comparable to other sources of errors, such as uncertainties in knowledge of aerosol scattering properties and of bidirectional reflectance in each pixel. However, most of the other errors have a random nature, while 3-D effects are systematic. They always increase the apparent reflectance of the dark targets and decrease the signal from the bright targets. As such, 3-D effects become important even at medium resolution, especially for off-nadir observations. Although our analysis was limited to I-D Lambertian surfaces, the results presented here are general enough to make quantitative conclusions in this still poorly studied but very important area. C1 Univ Baltimore, Goddard Space Flight Ctr, Joint Ctr Earth Syst, NASA, Greenbelt, MD 20771 USA. RP Lyapustin, AI (reprint author), Univ Baltimore, Goddard Space Flight Ctr, Joint Ctr Earth Syst, NASA, Greenbelt, MD 20771 USA. RI Lyapustin, Alexei/H-9924-2014 OI Lyapustin, Alexei/0000-0003-1105-5739 NR 24 TC 14 Z9 14 U1 0 U2 4 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 FEB PY 2001 VL 39 IS 2 BP 254 EP 263 DI 10.1109/36.905233 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 407AT UT WOS:000167249800004 ER PT J AU Remer, LA Wald, AE Kaufman, YJ AF Remer, LA Wald, AE Kaufman, YJ TI Angular and seasonal variation of spectral surface reflectance ratios: Implications for the remote sensing of aerosol over land SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB seasonal variability of surface reflectance using a hand-held spectrometer from a light aircraft, The data is used to test a procedure that allows us to estimate visible surface reflectance from the longer wavelength 2.1 mum channel (mid-IR), Estimating or avoiding surface reflectance in the visible is a vital first step in most algorithms that retrieve aerosol optical thickness over land targets. The data indicate that specular reflection found when viewing targets from the forward direction can severely corrupt the relationships between the visible and 2.1 mum reflectance that were derived from nadir data. There is a month by month variation in the ratios between the visible and the mid-IR, weakly correlated to the Normalized Difference Vegetation Index (NDVI), If specular reflection is not avoided, the errors resulting from estimating surface reflectance from the mid-IR exceed the acceptable limit of Delta rho similar to 0.01 in roughly 40% of the cases, using the current algorithm. This is reduced to 25% of the cases if specular reflection is avoided. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Sci Applicat Int Corp, Chantilly, VA 20151 USA. RP Remer, LA (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. NR 16 TC 48 Z9 54 U1 1 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD FEB PY 2001 VL 39 IS 2 BP 275 EP 283 DI 10.1109/36.905235 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA 407AT UT WOS:000167249800006 ER PT J AU Hall, DK Foster, JL Salomonson, VV Klein, AG Chien, JYL AF Hall, DK Foster, JL Salomonson, VV Klein, AG Chien, JYL TI Development of a technique to assess snow-cover mapping errors from space SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article DE moderate resolution imaging spectroradiometer; (MODIS); satellites; snow cover; snow mapping ID IMAGING SPECTRORADIOMETER MODIS; SURFACE ALBEDO; ACCURACY; SYSTEM; MODEL AB Following the December 18, 1999, launch of the Earth Observing System (EOS) Terra satellite, daily snow-cover mapping is performed automatically at a spatial resolution of 500 m, cloud-cover permitting, using moderate resolution imaging spectroradiometer (MODIS) data. This paper describes a technique for calculating global-scale snow mapping errors and provides estimates of Northern Hemisphere snow mapping errors based on prototype MODIS snow mapping algorithms. Field studies demonstrate that under cloud-free conditions, when snow cover is complete, snow mapping errors are small (< 1%) in all land covers studied except forests, where errors are often greater and more variable. Thus, the accuracy of Northern Hemisphere snow-cover maps is largely determined by percent of forest cover north of the snowline, From the 17-class International Geosphere-Biosphere Program (IGBP) land-cover maps of North America and Eurasia, we classify the Northern Hemisphere into seven land-cover classes and water. Estimated snow mapping errors in each of the land-cover classes are extrapolated to the entire Northern Hemisphere for areas north of the average continental snowline for each month. The resulting average monthly errors are expected to vary, ranging from about 5-10%, with the larger errors occurring during the months when snow covers the boreal forest in the Northern Hemisphere. As determined using prototype MODIS data, the annual average estimated error of the future Northern Hemisphere snow-cover maps is approximately 8% in the absence of cloud cover, assuming complete snow cover. Preliminary error estimates will be refined after MODIS data have been available for about one year. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Texas A&M Univ, Dept Geog, College Stn, TX 77843 USA. Gen Sci Corp, Laurel, MD 20707 USA. RP NASA, Goddard Space Flight Ctr, Code 661, Greenbelt, MD 20771 USA. EM dhall@glacier.gsfc.nasa.gov RI Hall, Dorothy/D-5562-2012 NR 33 TC 59 Z9 65 U1 3 U2 12 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 EI 1558-0644 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD FEB PY 2001 VL 39 IS 2 BP 432 EP 438 DI 10.1109/36.905251 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 407AT UT WOS:000167249800022 ER PT J AU McWatters, DA Lutes, G Caro, ER Tu, MR AF McWatters, DA Lutes, G Caro, ER Tu, MR TI Optical calibration phase locked loop for the shuttle radar topography mission SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Article DE interferometric phase calibration; optical phase locked loop; optical phase shifter AB The Shuttle Radar Topography Mission (SRTM) is an interferometric synthetic aperture radar system that flew on the space shuttle in February 2000, SRTM has an inboard antenna in the shuttle cargo bay and an outboard antenna at the end of a 60-m mast, extending from the cargo bay. In order to meet the elevation mapping accuracy requirement, the relative phase delay between the radar signals received via the outboard channel, compared with the inboard channel has to be known to within 8 degrees at 5.3 GHz. This paper describes the design solutions and constraints, the devices, the analysis, and validation used to implement an optical calibration loop for SRTM, The calibration method involves injecting a tone into one panel of the inboard antenna, and sending an optical copy of the tone via a fiber-optic cable to be injected into the outboard antenna. A portion of the optical signal is reflected off an outboard partial mirror and travels back via the fiber to the inboard calibration system. There, it is converted hack into a radio frequency tone and its phase is compared,vith the phase of the original tone. As the temperature of the mast fiber changes, a phase error is detected in the phase comparator. This error is used to control a custom designed optical phase shifter connected in series with the mast fiber, This phase-locked-loop guarantees that the phase of the calibration tone at the outboard stays within 1 degrees relative to the phase of the calibration tone at the inboard antenna. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP McWatters, DA (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 3 TC 2 Z9 2 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 0018-9456 J9 IEEE T INSTRUM MEAS JI IEEE Trans. Instrum. Meas. PD FEB PY 2001 VL 50 IS 1 BP 40 EP 46 DI 10.1109/19.903876 PG 7 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA 403UV UT WOS:000167061600006 ER PT J AU Jun, I AF Jun, I TI Effects of secondary particles on the total dose and the displacement damage in space proton environments SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article DE displacement damage; nonionizing energy loss; secondary effects by protons; spallation reactions; total dose ID SILICON AB MCNPX, a powerful Monte Carlo charged particle transport code, is introduced in this paper for space-radiation effect applications. By using MCNPX version 2.1.5, the enhancement of the total dose and the displacement damage due to secondary particles generated by the protons in the typical space radiation environments was assessed, then the results were compared to those obtained by the continuous slowing down approximation (CSDA) method. The comparison showed that the effects of the secondary particles were up to +7% for the total dose and up to +25% for the displacement damage when compared to the respective CSDA results in heavy shielding applications where trapped and solar protons dominate. Also presented in this paper is a method to compute the neutron/proton displacement cross sections by using MCNPX. The cross sections obtained show an excellent agreement with previously published values. C1 Boeing Satellite Syst, El Segundo, CA 90245 USA. RP Jun, I (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 21 TC 39 Z9 41 U1 1 U2 4 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 FEB PY 2001 VL 48 IS 1 BP 162 EP 175 DI 10.1109/23.907581 PN 2 PG 14 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA 409QJ UT WOS:000167394100004 ER PT J AU Stoica, A Zebulum, R Keymeulen, D Tawel, R Daud, T Thakoor, A AF Stoica, A Zebulum, R Keymeulen, D Tawel, R Daud, T Thakoor, A TI Reconfigurable VLSI architectures for evolvable hardware: From experimental field programmable transistor arrays to evolution-oriented chips SO IEEE TRANSACTIONS ON VERY LARGE SCALE INTEGRATION (VLSI) SYSTEMS LA English DT Article DE adaptive computing; evolvable hardware; field-programmable transistor arrays (FPTAs); genetic algorithms; reconfigurable VLSI architectures ID ANALOG AB Evolvable hardware (EHW) addresses on-chip adaptation and self-configuration through evolutionary algorithms. Current programmable devices, in particular the analog ones, lack evolution-oriented characteristics. This paper proposes an evolution-oriented field programmable transistor array (FPTA), reconfigurable at transistor level. The FPTA allows evolutionary experiments with reconfiguration at various levels of granularity. Experiments in SPICE simulations and directly on a reconfigurable FPTA chip demonstrate how the evolutionary approach can be used to automatically synthesize a variety of analog and digital 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 18 TC 56 Z9 59 U1 0 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 USA SN 1063-8210 J9 IEEE T VLSI SYST JI IEEE Trans. Very Large Scale Integr. (VLSI) Syst. PD FEB PY 2001 VL 9 IS 1 BP 227 EP 232 DI 10.1109/92.920839 PG 6 WC Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic SC Computer Science; Engineering GA 431FX UT WOS:000168622100027 ER PT J AU Cooper, D Pride, MW Brown, EL Risin, D Pellis, NR AF Cooper, D Pride, MW Brown, EL Risin, D Pellis, NR TI Suppression of antigen-specific lymphocyte activation in modeled microgravity SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Article DE space flight; space immunology; gravitational biology; immune suppression ID SPACEFLIGHT; LOCOMOTION; COLLAGEN; IMMUNITY; ASSAY AB Various parameters of immune suppression are observed in lymphocytes from astronauts during and after a space flight. it is difficult to ascribe this suppression to microgravity effects on immune cells in crew specimens, due to the complex physiological response to space flight and the resultant effect on in vitro immune performance. Use of isolated immune cells in true and modeled microgravity in immune performance tests, suggests a direct effect of microgravity on in vitro cellular function. Specifically, polyclonal activation of T-cells is severely suppressed in true and modeled microgravity. These recent findings suggest a potential suppression of oligoclonal antigen-specific lymphocyte activation in microgravity. We utilized rotating wall vessel (RWV) bioreactors as an analog of microgravity for cell cultures to analyze three models of antigen-specific activation. A mixed-lymphocyte reaction, as a model for a primary immune response, a tetanus toroid response and a Borrelia burgdorferi response, as models of a secondary immune response, were all suppressed in the RWV bioreactor. Our findings confirm that the suppression of activation observed with polyclonal models also encompasses oligoclonal antigen-specific activation. C1 NASA, Cellular Biotechnol Program, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. La Jolla Inst Allergy & Immunol, Div Immunochem, San Diego, CA 92121 USA. Wyeth Lederle Vaccines & Pediat, Dept Viral Immunol, Pearl River, NY 10965 USA. Texas A&M Univ, Inst Biosci & Technol, Dept Extracellular Matrix Biol, Houston, TX 77030 USA. Wyle Labs Life Sci Syst & Serv, Houston, TX 77058 USA. RP Pellis, NR (reprint author), NASA, Cellular Biotechnol Program, Lyndon B Johnson Space Ctr, 2101 NASA Rd 1,Mail Code SD12, Houston, TX 77058 USA. NR 13 TC 25 Z9 28 U1 2 U2 8 PU SOC IN VITRO BIOLOGY PI LARGO PA 9315 LARGO DR WEST, STE 25, LARGO, MD 20774 USA SN 1071-2690 J9 IN VITRO CELL DEV-AN JI In Vitro Cell. Dev. Biol.-Anim. PD FEB PY 2001 VL 37 IS 2 BP 63 EP 65 PG 3 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 422WA UT WOS:000168141200001 PM 11332738 ER PT J AU Risin, D Pellis, NR AF Risin, D Pellis, NR TI Modeled microgravity inhibits apoptosis in peripheral blood lymphocytes SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Article; Proceedings Paper CT Meeting and General Assembly of the European-Low-Gravity-Research-Association CY FEB 28-MAR 03, 1999 CL ROME, ITALY DE microgravity; apoptosis; immunity ID PROGRAMMED CELL-DEATH; T-LYMPHOCYTES; SIMULATED MICROGRAVITY; BCL-2 FAMILY; ACTIVATION; FAS; SPACEFLIGHT; LIGAND; BAX; HYPOGRAVITY AB Microgravity interferes with numerous lymphocyte functions (expression of cell surface molecules, locomotion, polyclonal and antigen-specific activation, and the protein kinase C activity in signal transduction). The latter suggests that gravity may also affect programmed cell death (PCD) in lymphocyte populations. To test this hypothesis, we investigated spontaneous, activation- and radiation-induced PCD in peripheral blood mononuclear cells exposed to modeled microgravity (MMG) using a rotating cell culture system. The results showed significant inhibition of radiation- and activation-induced apoptosis in MMG and provide insights into the potential mechanisms of this phenomenon. C1 NASA, Cellular Biotechnol Program, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Wyle Labs Life Sci Syst & Serv, Biotechnol Program, Houston, TX 77058 USA. RP Risin, D (reprint author), NASA, Cellular Biotechnol Program, Lyndon B Johnson Space Ctr, 2101 NASA Rd 1, Houston, TX 77058 USA. NR 42 TC 19 Z9 20 U1 0 U2 1 PU SOC IN VITRO BIOLOGY PI LARGO PA 9315 LARGO DR WEST, STE 25, LARGO, MD 20774 USA SN 1071-2690 J9 IN VITRO CELL DEV-AN JI In Vitro Cell. Dev. Biol.-Anim. PD FEB PY 2001 VL 37 IS 2 BP 66 EP 72 PG 7 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 422WA UT WOS:000168141200002 PM 11332739 ER PT J AU Khaoustov, VI Risin, D Pellis, NR Yoffe, B AF Khaoustov, VI Risin, D Pellis, NR Yoffe, B TI Microarray analysis of genes differentially expressed in HEPG2 cells cultured in simulated microgravity: Preliminary report SO IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-ANIMAL LA English DT Article DE DNA microarray; microgravity; gene expression; cell cultures ID HUMAN LIVER-CELLS; DNA MICROARRAYS; HYBRIDIZATION; SPACE AB Developed at NASA, the rotary cell culture system (RCCS) allows the creation of unique microgravity environment of low shear force, high-mass transfer, and enables three-dimensional (3D) cell culture of dissimilar cell types. Recently we demonstrated that a simulated microgravity is conducive for maintaining long-term cultures of functional hepatocytes and promote 3D cell assembly. Using deoxyribonucleic acid (DNA) microarray technology, it is now possible to measure the levels of thousands of different messenger ribonucleic acids (mRNAs) in a single hybridization step. This technique is particularly powerful for comparing gene expression in the same tissue under different environmental conditions. The aim of this research was to analyze gene expression of hepatoblastoma cell line (HepG2) during early stage of 3D-cell assembly in simulated microgravity. For this, mRNA from HepG2 cultured in the RCCS was analyzed by deoxyribonucleic acid microarray. Analyses of HepG2 mRNA by using 6K glass DNA microarray revealed changes in expression of 95 genes (overexpression of 85 genes and downregulation of 10 genes). Our preliminary results indicated that simulated microgravity modifies the expression of several genes and that microarray technology may provide new understanding of the fundamental biological questions of how gravity affects the development and function of individual cells. C1 Baylor Coll Med, Vet Affairs Med Ctr, Dept Med, Houston, TX 77030 USA. Wyle Labs, Dept Med, Houston, TX 77058 USA. NASA, Dept Med, Biotechnol Program, Houston, TX 77058 USA. RP Yoffe, B (reprint author), Baylor Coll Med, Vet Affairs Med Ctr, Dept Med, 151B,2002 Holcombe Blvd, Houston, TX 77030 USA. NR 18 TC 20 Z9 22 U1 2 U2 6 PU SOC IN VITRO BIOLOGY PI LARGO PA 9315 LARGO DR WEST, STE 25, LARGO, MD 20774 USA SN 1071-2690 J9 IN VITRO CELL DEV-AN JI In Vitro Cell. Dev. Biol.-Anim. PD FEB PY 2001 VL 37 IS 2 BP 84 EP 88 PG 5 WC Cell Biology; Developmental Biology SC Cell Biology; Developmental Biology GA 422WA UT WOS:000168141200005 PM 11332742 ER PT J AU Kawata, T Durante, M Furusawa, Y George, K Takai, N Wu, H Cucinotta, FA AF Kawata, T Durante, M Furusawa, Y George, K Takai, N Wu, H Cucinotta, FA TI Dose-response of initial G2-chromatid breaks induced in normal human fibroblasts by heavy ions SO INTERNATIONAL JOURNAL OF RADIATION BIOLOGY LA English DT Article ID PREMATURE CHROMOSOME CONDENSATION; HUMAN INTERPHASE CHROMOSOMES; ALPHA-PARTICLES; MAMMALIAN-CELLS; MUTATION-INDUCTION; CHARGED-PARTICLES; INACTIVATION; DAMAGE; BEAMS; ACCUMULATION AB Purpose: To investigate initial chromatid breaks in prematurely condensed G2 chromosomes following exposure to heavy ions of different LET. Material and methods: Exponentially growing human fibroblast cells AG1522 were irradiated with gamma -rays, energetic carbon (13 keV/mum, 80 keV/mum) ions. Chromosomes were prematurely condensed using calyculin-A. Initial chromatid-type and isochromatid breaks in G2 cells were scored. Results: The dose-response curves for total chromatid breaks were linear regardless of radiation type. The relative biological effectiveness (RBE) showed a LET-dependent increase, peaking around 2.7 at 55 80 keV/mum and decreasing at higher LET. The dose-response curves for isochromatid-type breaks were linear for high-LET radiations, but linear-quadratic for gamma -rays and 13 keV/mum carbon ions. The RBE for the induction of isochromatid breaks obtained from linear components increased rapidly between 13 keV/mum (about 7) and 80 keV/mum carbon (about 71), and decreased gradually until 440 keV/mum iron ions (about 66). Conclusions: High-LET radiations are more effective at inducing isochromatid breaks, while low-LET radiations are more effective at including chromatid-type breaks. The densely ionizing track structures of heavy ions and the proximity of sister chromatids in G2 cells result in an increase in isochromatid breaks. C1 NASA, Lyndon B Johnson Space Ctr, Radiat Biophys Lab, Houston, TX 77058 USA. Univ Naples Federico II, Dept Phys, Naples, Italy. Natl Inst Radiol Sci, Int Space Radiat Lab, Chiba 260, Japan. Wyle Labs, Houston, TX 77058 USA. Kelsey Seybold Clin, Johnson Space Ctr, Houston, TX 77058 USA. RP Kawata, T (reprint author), NASA, Lyndon B Johnson Space Ctr, Radiat Biophys Lab, Mail Code SN, Houston, TX 77058 USA. RI Durante, Marco/K-1315-2014; OI Durante, Marco/0000-0002-4615-553X NR 38 TC 28 Z9 42 U1 0 U2 2 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 FEB PY 2001 VL 77 IS 2 BP 165 EP 174 PG 10 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 403RC UT WOS:000167055400003 PM 11236923 ER PT J AU George, K Wu, H Willingham, V Furusawa, Y Kawata, T Cucinotta, FA AF George, K Wu, H Willingham, V Furusawa, Y Kawata, T Cucinotta, FA TI High- and low-LET induced chromosome damage in human lymphocytes: a time-course of aberrations in metaphase and interphase SO INTERNATIONAL JOURNAL OF RADIATION BIOLOGY LA English DT Article ID IN-SITU HYBRIDIZATION; BLOOD-LYMPHOCYTES; CHARGED-PARTICLES; ALPHA-PARTICLES; V79 CELLS; X-RAYS; RADIATION; EXCHANGE; BIODOSIMETRY; FREQUENCIES AB Purpose: To investigate how cell-cycle delays in human peripheral lymphocytes affect the expression of complex chromosome damage in metaphase following high- and low-LET radiation exposure. Materials and methods: Whole blood was irradiated in vitro with a low and a high dose of 1 GeV u(-1) iron particles, 400 MeV u-1 neon particles or gamma -rays. Lymphocytes were cultured and metaphase cells were collected at different time points after 48 84 h in culture. Interphase chromosomes were prematurely condensed using calyculin-A, either 18 or 72 h after exposure to iron particles or gamma -rays. Cells in first division were analysed using a combination of FISH whole-chromosome painting and DAPI/Hoechst 33258 harlequin staining. Results: There was a delay in expression of chromosome damage in metaphase that was LET- and dose-dependent. This delay was mostly related to the late emergence of complex-type damage into metaphase. Yields of damage in PCC collected 48 h after irradiation with iron particles were similar to values obtained from cells undergoing mitosis after prolonged incubation. Conclusion: The yield of high-LET radiation-induced complex chromosome damage could be underestimated when analysing metaphase cells collected at one time point after irradiation. Chemically induced PCC is a more accurate technique since problems with complicated cell-cycle delays are avoided. C1 Wyle Labs, Houston, TX 77058 USA. Kelsey Seybold Clin, Houston, TX 77058 USA. NASA, Lyndon B Johnson Space Ctr, Radiat Biophys Lab, Houston, TX 77058 USA. Natl Inst Radiol Sci, Int Space Radiat Lab, Chiba 260, Japan. RP George, K (reprint author), Wyle Labs, 1290 Hercules Dr, Houston, TX 77058 USA. NR 27 TC 72 Z9 76 U1 0 U2 4 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 FEB PY 2001 VL 77 IS 2 BP 175 EP 183 PG 9 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 403RC UT WOS:000167055400004 PM 11236924 ER PT J AU Hilburger, MW Britt, VO Nemeth, MP AF Hilburger, MW Britt, VO Nemeth, MP TI Buckling behavior of compression-loaded quasi-isotropic curved panels with a circular cutout SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article DE buckling; curved panels; cutouts; compression loads ID THIN AB Results from a numerical and experimental study of the response of compression-loaded quasi-isotropic curved panels with a centrally located circular cutout are presented. The numerical results were obtained by using a geometrically nonlinear finite element analysis code. The effects of cutout size, panel curvature and initial geometric imperfections on the overall response of compression-loaded panels are described. In addition, results are presented from a numerical parametric study that indicate the effects of elastic circumferential edge restraints on the prebuckling and buckling response of a selected panel and these numerical results are compared to experimentally measured results. These restraints are used to identify the effects of circumferential edge restraints that are introduced by the test fixture that was used in the present study. It is shown that circumferential edge restraints can introduce substantial nonlinear prebuckling deformations into shallow compression-loaded curved panels that can result in a significant increase in buckling load. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Natl Res Council, Washington, DC 20418 USA. Gulf Stream Aerosp Corp, Savannah, GA 31402 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Hilburger, MW (reprint author), Natl Res Council, Washington, DC 20418 USA. NR 17 TC 20 Z9 20 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0020-7683 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD FEB PY 2001 VL 38 IS 9 BP 1495 EP 1522 DI 10.1016/S0020-7683(00)00114-1 PG 28 WC Mechanics SC Mechanics GA 399JZ UT WOS:000166809000003 ER PT J AU Nyberg, KL Diller, KR Wissler, EH AF Nyberg, KL Diller, KR Wissler, EH TI Model of human/liquid cooling garment interaction for space suit automatic thermal control SO JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID HEAT-STORAGE; BODY AB The Wissler human thermoregulation model was augmented to incorporate simulation of a space suit thermal control system that includes interaction with a liquid cooled garment (LCG) and ventilation gas flow through the suit. The model was utilized in the design process of an automatic controller intended to maintain thermal neutrality of an exercising subject wearing a liquid cooling garment. An experimental apparatus was designed and built to test the efficacy of specific physiological state measurements to provide feedback data for input to the automatic control algorithm. Control of the coolant inlet temperature to the LCG was based on evaluation of transient physiological parameters that describe the thermal state of the subject, including metabolic rate, skin temperatures, and core temperature. Experimental evaluation of the control algorithm function was accomplished in an environmental chamber under conditions that simulated the thermal environment of a space suit and transient metabolic work lends typical of astronaut extravehicular activity (EVA). The model was also applied to analyze experiments to evaluate performance of the automatic control system in maintaining thermal comfort during extensive transient metabolic profiles for a range of environmental temperatures. Finally, the model was used to predict the efficacy of the LCG thermal controller for providing thermal comfort for a variety of regimens that may be encountered in future space missions. Simulations with the Wissler model accurately predicted the thermal interaction between the subject and LCG for a wide range of metabolic profiles and environmental conditions and matched the function of the automatic temperature controller for inlet cooling water to the LCG. C1 Univ Texas, Dept Mech Engn, Biomed Engn Program, Austin, TX 78712 USA. Univ Texas, Dept Chem Engn, Biomed Engn Program, Austin, TX 78712 USA. RP Nyberg, KL (reprint author), NASA, Lyndon B Johnson Space Ctr, Mail Code EC2, Houston, TX 77085 USA. NR 10 TC 15 Z9 15 U1 2 U2 6 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 FEB PY 2001 VL 123 IS 1 BP 114 EP 120 DI 10.1115/1.1336147 PG 7 WC Biophysics; Engineering, Biomedical SC Biophysics; Engineering GA 407CT UT WOS:000167254400016 PM 11277296 ER PT J AU Vanapalli, SR Kambhampati, SP Putcha, L Bourne, DWA AF Vanapalli, SR Kambhampati, SP Putcha, L Bourne, DWA TI A liquid chromatographic method for the simultaneous determination of promethazine and three of its metabolites in plasma using electrochemical and UV detectors SO JOURNAL OF CHROMATOGRAPHIC SCIENCE LA English DT Article C1 Univ Oklahoma, Hlth Sci Ctr, Coll Pharm, Oklahoma City, OK 73117 USA. NASA, Lyndon B Johnson Space Ctr, Life Sci Res Labs, Houston, TX 77058 USA. RP Bourne, DWA (reprint author), Univ Oklahoma, Hlth Sci Ctr, Coll Pharm, Oklahoma City, OK 73117 USA. NR 4 TC 14 Z9 15 U1 0 U2 1 PU PRESTON PUBLICATIONS INC PI NILES PA 7800 MERRIMAC AVE PO BOX 48312, NILES, IL 60648 USA SN 0021-9665 J9 J CHROMATOGR SCI JI J. Chromatogr. Sci. PD FEB PY 2001 VL 39 IS 2 BP 70 EP 72 PG 3 WC Biochemical Research Methods; Chemistry, Analytical SC Biochemistry & Molecular Biology; Chemistry GA 400LX UT WOS:000166874000006 PM 11245229 ER PT J AU Sommer, AP Pinheiro, ALB Mester, AR Franke, RP Whelan, HT AF Sommer, AP Pinheiro, ALB Mester, AR Franke, RP Whelan, HT TI Biostimulatory windows in low-intensity laser activation: Lasers, scanners, and NASA's light-emitting diode array system SO JOURNAL OF CLINICAL LASER MEDICINE & SURGERY LA English DT Article ID LOW-POWER LASER; MEDICAL APPLICATIONS; ENERGY DENSITY; CELLS; IRRADIATION; PARAMETERS; LILAB AB Objective: The purpose of this study was to assess and to formulate physically an irreducible set of irradiation parameters that could be relevant in the achieving reproducible light-induced effects in biological systems, both in vitro and in vivo. Background Data: Light-tissue interaction studies focusing on the evaluation of irradiation thresholds are basic for the extensively growing applications for medical lasers and related light-emitting systems. These thresholds are of central interest in the rejuvenation of collagens, photorefractive keratectomy, and wound healing. Methods: There is ample evidence that the action of light in biological systems depends at least on two threshold parameters: the energy density and the intensity. Depending on the particular light delivery system coupled to an irradiation source, the mean energy density and the local intensity have to be determined separately using adequate experimental methods. Results: From the observations of different research groups and our own observations, we conclude that the threshold parameters energy density and intensity are biologically independent from each other. Conclusions: This independence is of practical importance, at least for the medical application of photobiological effects achieved at low-energy density levels, accounting for the success and the failure in most of the cold laser uses since Mester's pioneering work. C1 Univ Fed Bahia, Dept Diagnost & Therapeut, Sch Dent, BR-40110150 Salvador, BA, Brazil. Univ Ulm, ENSOMA Lab, Dept Biomat, Cent Inst Biomed Engn, D-89081 Ulm, Germany. Semmelweis Univ, Dept Radiol & Oncotherapy, H-1082 Budapest, Hungary. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Pinheiro, ALB (reprint author), Univ Fed Bahia, Dept Diagnost & Therapeut, Sch Dent, Av Araujo Pinha,62 Canela, BR-40110150 Salvador, BA, Brazil. RI Pinheiro, Antonio Luiz/A-1962-2008 OI Pinheiro, Antonio Luiz/0000-0002-5805-0321 NR 36 TC 153 Z9 157 U1 1 U2 15 PU MARY ANN LIEBERT INC PI NEW ROCHELLE PA 140 HUGUENOT STREET, 3RD FL, NEW ROCHELLE, NY 10801 USA SN 1044-5471 J9 J CLIN LASER MED SUR JI J. Clin. Laser Med. Sur. PD FEB PY 2001 VL 19 IS 1 BP 29 EP 33 DI 10.1089/104454701750066910 PG 5 WC Engineering, Biomedical; Surgery SC Engineering; Surgery GA 406CZ UT WOS:000167198500006 PM 11547815 ER PT J AU Walker, JS Croll, A Szofran, FR AF Walker, JS Croll, A Szofran, FR TI Thermoelectromagnetic convection in floating zone silicon growth with a nonaxisymmetric temperature and a strong axial magnetic field SO JOURNAL OF CRYSTAL GROWTH LA English DT Article DE convection; magnetic fields; floating zone technique; semiconducting silicon ID CRYSTAL-GROWTH AB Thermoelectromagnetic convection (TEMC) is the melt motion driven by the interaction of an externally applied magnetic field and the thermoelectric current due to variations of the absolute thermoelectric power and of the temperature. This paper presents numerical solutions for the three-dimensional TEMC in a simplified model of the floating zone process with a nonaxisymmetric temperature variation over the crystal-melt interface. The axial magnetic field is sufficiently strong that inertial effects are negligible, so that each azimuthal Fourier component of the TEMC can be treated independently. Results are presented for the cos theta and cos(2 theta) components of the TEMC. The results show that a very small deviation from axisymmetry in the temperature produces a very large deviation from axisymmetry in the radial and axial components of the TEMC velocity. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Univ Illinois, Dept Mech & Ind Engn, Urbana, IL 61801 USA. TU Bergakad Freiberg, Inst NE Met & Reinststoffe, D-09599 Freiberg, Germany. NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA. RP Walker, JS (reprint author), Univ Illinois, Dept Mech & Ind Engn, 1206 W Green St, Urbana, IL 61801 USA. RI Croell, Arne/A-2480-2013 OI Croell, Arne/0000-0002-8673-9994 NR 12 TC 4 Z9 5 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD FEB PY 2001 VL 223 IS 1-2 BP 73 EP 82 DI 10.1016/S0022-0248(00)01015-0 PG 10 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA 408BL UT WOS:000167306600011 ER PT J AU Ruthruff, E Johnston, JC Van Selst, M AF Ruthruff, E Johnston, JC Van Selst, M TI Why practice reduces dual-task interference SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Article ID OVERLAPPING TASKS; 2 THINGS; AUTOMATICITY; PERFORMANCE; ELIMINATION; MECHANISMS; BOTTLENECK; ATTENTION; LOCUS AB M. A. Van Selst, E. Ruthruff, and J. C. Johnston (1999) found that practice dramatically reduced dual-task interference in a Psychological Refractory Period (PRP) paradigm with 1 vocal response and I manual response. Results from 3 further experiments using the highly trained participants of M. A. Van Selst ct al. (1999) support 4 main conclusions: (a) A processing bottleneck exists even after extensive practice; (b) the principal cause of the reduction in PRP interference with practice is shortening of Task 1 bottleneck stages; (c) a secondary cause is that 1 or more, but not all, of the Task 2 substages that are postponed before practice are not postponed after practice (i.e., become automatized); and (d) the extent of PRP reduction with practice depends on the modalities of the 2 responses. A control experiment with 2 manual response tasks showed less PRP reduction with practice than that found by Van Selst et al. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. San Jose State Univ, Dept Psychol, San Jose, CA 95192 USA. RP Ruthruff, E (reprint author), NASA, Ames Res Ctr, MS 262-4, Moffett Field, CA 94035 USA. NR 45 TC 94 Z9 95 U1 3 U2 13 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 USA SN 0096-1523 J9 J EXP PSYCHOL HUMAN JI J. Exp. Psychol.-Hum. Percept. Perform. PD FEB PY 2001 VL 27 IS 1 BP 3 EP 21 DI 10.1037//0096-1523.27.1.3 PG 19 WC Psychology; Psychology, Experimental SC Psychology GA 399NL UT WOS:000166819200001 PM 11248938 ER PT J AU Park, HG Gharib, M AF Park, HG Gharib, M TI Experimental study of heat convection from stationary and oscillating circular cylinder in cross flow SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Article DE convection; cooling; cylinder; enhancement; entrainment; experimental; fluids; forced convection; heat transfer; heat exchangers; image processing; nonintrusive diagnostics; recirculating; separated; surface; temperature; thermal; unsteady; vibrating; vortex; wakes ID WAKE; TRANSPORT; TURBULENT AB An experimental study is made on the processes of heat transfer from the surface of a forced oscillating cylinder in a crossflow. A range of oscillation amplitude (A/D =0.1,0.2), forced oscillation frequency (02.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 407BD UT WOS:000167250800003 ER PT J AU Bosilovich, MG Schubert, SD AF Bosilovich, MG Schubert, SD TI Precipitation recycling over the central United States diagnosed from the GEOS-1 Data Assimilation System SO JOURNAL OF HYDROMETEOROLOGY LA English DT Article ID NORTH-AMERICAN DROUGHT; 1993 MIDWESTERN FLOOD; SOIL-MOISTURE; NUMERICAL-SIMULATION; PHYSICAL PROCESSES; GLOBAL CLIMATE; MODEL; LAND; TRANSPORT; WATER AB Precipitation recycling has been computed for 15 yr of reanalysis data from the National Aeronautics and Space Administration Goddard Earth Observing System (GEOS-1) Data Assimilation System using monthly mean hydrological data and a bulk diagnostic recycling model. This study focuses on the central United States and the extreme summers of 1988 (drought) and 1993 (flood). It is found that the 1988 summer recycling ratio is larger than that of 1993, and that the 1988 recycling ratio is much larger than average. The 1993 recycling ratio was less than average during the summer, but it was larger than average during the springtime, when the soil was being primed for flooding. In addition, the magnitude of summertime recycled precipitation was smaller than average in both 1988 and 1993. During the summer of 1993, the extremely large moisture transport dominates evaporation as the source of water for the extreme summer precipitation. The diagnosed recycling data show that the recycled precipitation is large when moisture transport is weak and convergence and evaporation are large. The analysis identifies the summer of 1989 as having the largest magnitude of recycled precipitation, resulting from a combination of low moisture transport and high moisture convergence. C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Bosilovich, MG (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 USA. RI Bosilovich, Michael/F-8175-2012 NR 36 TC 48 Z9 49 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 1525-755X J9 J HYDROMETEOROL JI J. Hydrometeorol. PD FEB PY 2001 VL 2 IS 1 BP 26 EP 35 DI 10.1175/1525-7541(2001)002<0026:PROTCU>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 407BD UT WOS:000167250800004 ER PT J AU Huffman, GJ Adler, RF Morrissey, MM Bolvin, DT Curtis, S Joyce, R McGavock, B Susskind, J AF Huffman, GJ Adler, RF Morrissey, MM Bolvin, DT Curtis, S Joyce, R McGavock, B Susskind, J TI Global precipitation at one-degree daily resolution from multisatellite observations SO JOURNAL OF HYDROMETEOROLOGY LA English DT Article ID PASSIVE MICROWAVE; RAINFALL; PROJECT; DATASET; ERROR; INDEX AB The One-Degree Daily (1DD) technique is described Tor producing globally complete daily estimates of precipitation on a 1 degrees x 1 degrees lat/long grid from currently available observational data. Where possible (40 degrees N40 degreesS), the Threshold-Matched Precipitation Index (TMPI) provides precipitation estimates in which the 3-hourly infrared brightness temperatures (IR T-b) are compared with a threshold and all "cold" pixels are given a single precipitation rate. This approach is an adaptation of the Geoatationary Operational Environmental Satellite Precipitation Index, but for the TMPI the IR T-b threshold and conditional min rate are set locally by month from Special Sensor Microwave Imager-based precipitation frequency and the Global Precipitation Climatology Project (GPCP) satellite-gauge (SG) combined monthly precipitation estimate, respectively. At higher latitudes the 1DD features a rescaled daily Television and Infrared Observation Satellite Operational Vertical Sounder (TOVS) precipitation. The frequency of rain days in the TOVS is scaled down to match that in the TMPI at the data boundaries, and the resulting nonzero TOVS values are scaled locally to sum to the SC; (which is a globally complete monthly product). The GPCP has approved the IDD as an official product, and data have been produced for 1997 through 1999, with production continuing a few months behind real time (to allow access to monthly input data). The time series of the daily IDD global images shows good continuity in time and across the data boundaries. Various examples are shown to illustrate uses. Validation for individual gridbox values shows a very high mean absolute error, but it improves quickly when users perform time/space averaging according to their own requirements. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Sci Syst & Applicat Inc, Lanham, MD USA. Environm Verificat & Anal Ctr, Norman, OK USA. Univ Maryland, Joint Ctr Earth Syst Technol, Baltimore, MD 21201 USA. NOAA, NWS, NCEP, Climate Predict Ctr, Washington, DC USA. Res & Data Syst Corp, Greenbelt, MD USA. RP Huffman, GJ (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Code 912, Greenbelt, MD 20771 USA. 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 853 Z9 894 U1 3 U2 40 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 1525-755X J9 J HYDROMETEOROL JI J. Hydrometeorol. PD FEB PY 2001 VL 2 IS 1 BP 36 EP 50 DI 10.1175/1525-7541(2001)002<0036:GPAODD>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 407BD UT WOS:000167250800005 ER PT J AU Ray, RD AF Ray, RD TI Inversion of oceanic tidal currents from measured elevations SO JOURNAL OF MARINE SYSTEMS LA English DT Article DE tides; tidal currents; tidal charts; volume transports ID ACOUSTIC TRANSMISSIONS; TOPEX/POSEIDON ALTIMETRY; ASSIMILATING DATA; PACIFIC-OCEAN; LEAST-SQUARES; DEEP-OCEAN; TIDES; MODELS; ENERGY AB The problem of deducing tidal current velocities from measured tidal elevations is considered. Emphasis is given to global scales for which accurate cotidal charts based on satellite altimetry are readily available. Barotropic tidal currents are deduced from a recent altimetric tide solution by solving the two-dimensional momentum equations and the continuity equation in a least squares fashion. This approach represents a middle ground between commonly used data assimilation schemes and simple local solutions of the momentum equations. The estimated velocities are compared with those of other available global models, with acoustic velocity measurements, and with current meter measurements. Agreement with acoustic measurements is especially good; RMS discrepancies are consistently less than 2 mm s(-1). The method appears to be a useful tool for investigating various aspects of tidal dynamics. Published by Elsevier Science B.V. C1 NASA, Terr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Ray, RD (reprint author), NASA, Terr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RI Ray, Richard/D-1034-2012 NR 41 TC 21 Z9 22 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0924-7963 J9 J MARINE SYST JI J. Mar. Syst. PD FEB PY 2001 VL 28 IS 1-2 BP 1 EP 18 DI 10.1016/S0924-7963(00)00081-6 PG 18 WC Geosciences, Multidisciplinary; Marine & Freshwater Biology; Oceanography SC Geology; Marine & Freshwater Biology; Oceanography GA 419BE UT WOS:000167928800001 ER PT J AU Goldsby, JC Halbig, MC AF Goldsby, JC Halbig, MC TI Induction of through-thickness temperature gradients in thin shell ceramic composite cylinders by thermal radiation SO JOURNAL OF MATERIALS SCIENCE LETTERS LA English DT Article C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Goldsby, JC (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 10 TC 0 Z9 0 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 FEB PY 2001 VL 20 IS 4 BP 337 EP 339 DI 10.1023/A:1006725402375 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA 417WZ UT WOS:000167859600014 ER PT J AU Miller, CE Drouin, BJ AF Miller, CE Drouin, BJ TI The X-1(2)Pi(3/2) and X-2(2)Pi(1/2) potential energy surfaces of FO SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID SPIN-ORBIT; DIATOMIC-MOLECULES; ELECTRONIC STATES; HIGH-RESOLUTION; HALOGEN OXIDES; DIPOLE-MOMENT; AB-INITIO; SPECTROSCOPY; ABINITIO; SPECTRUM AB The X(1)(2)Pi (3/2) and X(2)(2)Pi (1/2) potential energy curves of the FO free radical have been determined from a fit to the available high-resolution spectroscopic data. The data set spans the vibrational states v = 0-7 and includes X(2)(2)Pi (1/2) <-- X(1)(2)Pi (3/2) fine-structure transitions. The determinable spectroscopic constants provide an excellent description of the equilibrium properties of both the X-1 and X-2 states in addition to the vibrational dependence of the spin-orbit coupling constant. The experimental properties of FO are used to evaluate the performance of different ab initio methods for describing the F-O bond. (C) 2001 Academic Press. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Haverford Coll, Dept Chem, Haverford, PA 19041 USA. RP Miller, CE (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 33 TC 19 Z9 19 U1 0 U2 7 PU ACADEMIC PRESS INC PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD FEB PY 2001 VL 205 IS 2 BP 312 EP 318 DI 10.1006/jmsp.2000.8257 PG 7 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA 404XX UT WOS:000167128600014 ER PT J AU Fijany, A Toomarian, BN AF Fijany, A Toomarian, BN TI New design for quantum dots cellular automata to obtain fault tolerant logic gates SO JOURNAL OF NANOPARTICLE RESEARCH LA English DT Article DE Quantum dots based computing; Quantum dots Cellular Automata; quantum dots logic gates; fault tolerant logic gates; Majority Gate ID DEVICES AB In this paper, we analyze fault tolerance properties of the Majority Gate, as the main logic gate for implementation with Quantum dots Cellular Automata (QCA), in terms of fabrication defect. Our results demonstrate the poor fault tolerance properties of the conventional design of Majority Gate and thus the difficulty in its practical application. We propose a new approach to the design of QCA-based Majority Gate by considering two-dimensional arrays of QCA cells rather than a single cell for the design of such a gate. We analyze fault tolerance properties of such Block Majority Gates in terms of inputs misalignment and irregularity and defect (missing cells) in assembly of the array. We present simulation results based on semiconductor implementation of QCA with an intermediate dimensional dot of about 5 nm in size as opposed to magnetic dots of greater than 100 nm or molecular dots of 2-5Angstrom. Our results clearly demonstrate the superior fault tolerance properties of the Block Majority Gate and its greater potential for a practical realization. We also show the possibility of designing fault tolerant QCA circuits by using Block Majority Gates. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Fijany, A (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 47 Z9 47 U1 0 U2 4 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 1388-0764 J9 J NANOPART RES JI J. Nanopart. Res. PD FEB PY 2001 VL 3 IS 1 BP 27 EP 37 DI 10.1023/A:1011415529354 PG 11 WC Chemistry, Multidisciplinary; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary SC Chemistry; Science & Technology - Other Topics; Materials Science GA 519MC UT WOS:000173729200005 ER PT J AU Vaidyanathan, H Kelly, WH Rao, G AF Vaidyanathan, H Kelly, WH Rao, G TI Heat dissipation in a lithium ion cell SO JOURNAL OF POWER SOURCES LA English DT Article DE heat dissipation; lithium ion cell; radiative calorimeter ID BATTERIES; ENERGY AB A comparative study of the heat dissipated by a 3.3 A h LixC/LiNiO2 cell and a 1.25 A h LixC/75% LiCoO2, 25% LiNiO2 cell was conducted through experimental heat rate measurements using a radiative calorimeter. The specific heat of the cell was determined experimentally to be 0.969 J/degreesC g for the LiNiO2 cell and 0.946 J/degreesC g for the LixC/75% LiCoO2, 25% LiNiO2 cell. The LixC/LiNiO2 cell had a higher self-discharge rate than the LixC/75% LiCoO2, 25% LiNiO2 cell. The heat dissipated during discharge increased with the rate of discharge. During charge, initial endothermic cooling and subsequent exothermic heating beyond 55% state-of-charge were observed. At the C/2 rate of discharge (medium rate), the heat dissipated was 17 mW/cm(3) for the LixC/LiNiO2 cell and 11.2 mW/cm(3) for the LixC/75% LiCoO2, 25% LiNiO2 cell. The experimental values obtained for the heat dissipation at various charge and discharge rates were used to calculate thermoneutral potentials of 3.698 and 3.836 V for the LixC/LiNiO2 and LixC/75% LiCoO2, 25% LiNiO2 cells, respectively. The proposed values for thermoneutral potential may explain the endothermic cooling during charge and the negative temperature coefficient for cell voltage. (C) 2001 Elsevier Science B.V. All rights reserved. C1 COMSAT Labs, Clarksburg, MD USA. William H Kelly & Associates, Gaithersburg, MD USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Vaidyanathan, H (reprint author), COMSAT Labs, Clarksburg, MD USA. NR 10 TC 10 Z9 10 U1 0 U2 8 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0378-7753 J9 J POWER SOURCES JI J. Power Sources PD FEB 1 PY 2001 VL 93 IS 1-2 BP 112 EP 122 DI 10.1016/S0378-7753(00)00550-4 PG 11 WC Chemistry, Physical; Electrochemistry; Energy & Fuels; Materials Science, Multidisciplinary SC Chemistry; Electrochemistry; Energy & Fuels; Materials Science GA 399WH UT WOS:000166836900016 ER PT J AU Lissenden, CJ Arnold, SM Saleeb, AF AF Lissenden, CJ Arnold, SM Saleeb, AF TI Plastic coupling and stress relaxation during nonproportional axial-shear strain-controlled loading SO JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT Pressure Vessels and Piping Conference of the American-Society-of-Mechanical-Engineers CY JUL 23-27, 2000 CL SEATTLE, WASHINGTON SP Amer Soc Mech Engineers AB A nonproportional strain-controlled load path consisting of two segments was applied to the cobalt-based alloy Haynes 188 at 650 degreesC. The first segment was purely axial; the axial strain was then held constant while the shear strain was increased during the second segment. The alloy exhibited about a 95-percent reduction in axial stress (298 to 15 MPa) during shear straining. This reduction was due primarily to plastic coupling, but time-dependent stress relaxation also occurred. A rate-independent plasticity model approximated the stress reduction due to plastic coupling reasonably well, but as expected was unable to account for time-dependent stress relaxation. A viscoplasticity model capable of predicting the interaction between stress relaxation and plastic coupling also predicted the plastic coupling reasonably well. The accuracy of the viscoplastic model is shown to depend greatly upon the set of nonunique nonunique material parameters, which must be characterized from a sufficiently large range of load histories. C1 Penn State Univ, Dept Engn Sci & Mech, University Pk, PA 16802 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. Univ Akron, Dept Civil Engn, Akron, OH 44325 USA. RP Lissenden, CJ (reprint author), Penn State Univ, Dept Engn Sci & Mech, University Pk, PA 16802 USA. NR 6 TC 1 Z9 1 U1 1 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA THREE PARK AVE, NEW YORK, NY 10016-5990 USA SN 0094-9930 J9 J PRESS VESS-T ASME JI J. Press. Vessel Technol.-Trans. ASME PD FEB PY 2001 VL 123 IS 1 BP 81 EP 87 DI 10.1115/1.1344883 PG 7 WC Engineering, Mechanical SC Engineering GA 412QX UT WOS:000167566800012 ER PT J AU Vickers, ZM Rice, BL Rose, MS Lane, HW AF Vickers, ZM Rice, BL Rose, MS Lane, HW TI Simulated microgravity [bed rest] has little influence on taste, odor or trigeminal sensitivity SO JOURNAL OF SENSORY STUDIES LA English DT Article AB Anecdotal evidence suggests that astronauts' perceptions of foods in space flight may differ from their perceptions of the same foods on Earth. Fluid shifts toward the head experienced in space may alter the astronauts' sensitivity to odors and tastes, producing altered perceptions. Our objective was to determine whether head-down bed rest, which produces similar fluid shifts, would produce changes in sensitivity to taste, odor or trigeminal sensations. Six subjects were rested three times prior to bed rest, three times during bed rest and two times after bed rest to determine their threshold sensitivity to the odors isoamylbutyrate and menthone, the tastants sucrose, sodium chloride, citric acid, quinine and monosodium glutamate, and to capsaicin. Thresholds were measured using a modified staircase procedure. Self-reported congestion was also recorded at each test time. Thresholds for monosodium glutamate where slightly higher during bed rest. None of the other thresholds were altered by bed rest. C1 Univ Minnesota, Dept Food Sci & Nutr, St Paul, MN 55108 USA. KRUG Life Sci, Houston, TX USA. S Dakota State Univ, Dept Nutr & Food Sci, Brookings, SD 57007 USA. NASA, Lyndon B Johnson Space Ctr, Nutr Biochem Lab, Houston, TX USA. RP Vickers, ZM (reprint author), Univ Minnesota, Dept Food Sci & Nutr, 1334 Eckles Ave, St Paul, MN 55108 USA. NR 10 TC 5 Z9 5 U1 0 U2 3 PU FOOD NUTRITION PRESS INC PI TRUMBULL PA 6527 MAIN ST, P O BOX 374, TRUMBULL, CT 06611 USA SN 0887-8250 J9 J SENS STUD JI J. Sens. Stud. PD FEB PY 2001 VL 16 IS 1 BP 23 EP 32 DI 10.1111/j.1745-459X.2001.tb00288.x PG 10 WC Food Science & Technology SC Food Science & Technology GA 404RB UT WOS:000167113500003 PM 12238516 ER PT J AU Dulchavsky, SA Schwarz, KL Kirkpatrick, AW Billica, RD Williams, DR Diebel, LN Campbell, MR Sargysan, AE Hamilton, DR AF Dulchavsky, SA Schwarz, KL Kirkpatrick, AW Billica, RD Williams, DR Diebel, LN Campbell, MR Sargysan, AE Hamilton, DR TI Prospective evaluation of thoracic ultrasound in the detection of pneumothorax SO JOURNAL OF TRAUMA-INJURY INFECTION AND CRITICAL CARE LA English DT Article; Proceedings Paper CT 60th Annual Meeting of the American-Association-for-the-Surgery-of Trauma CY OCT 11-15, 2000 CL SAN ANTONIO, TEXAS SP Amer Assoc Surg Trauma DE pneumothorax; ultrasound; space medicine ID DIAGNOSIS AB Background: Thoracic ultrasound may rapidly diagnose pneumothorax when radiographs are unobtainable; the accuracy is not known. Methods: We prospectively evaluated thoracic ultrasound detection of pneumothorax in patients at high suspicion of pneumothorax. The presence of "lung sliding" or "comet tail" artifacts were determined in patients by ultrasound before radiologic verification of pneumo-thorax by residents instructed in thoracic ultrasound. Results were compared with standard radiography, Results: There were 382 patients enrolled; the cause of injury was blunt (281 of 382), gunshot wound (22 of 382), stab wound (61 of 382), and spontaneous (18 of 382), Pneumothorax was demonstrated on chest radiograph in 39 patients and confirmed by ultrasound in 37 of 39 patients (95% sensitivity); two pneumothoraces could not be diagnosed because of subcutaneous air; the true-negative rate was 100%. Conclusion: Thoracic ultrasound reliably diagnoses pneumothorax. Expansion of the focused abdominal sonography for trauma (FAST) examination to include the thorax should he investigated for terrestrial and space medical applications. C1 Wayne State Univ, Sch Med, Dept Surg, Detroit, MI 48201 USA. Vancouver Gen Hosp, Vancouver, BC, Canada. NASA, Lyndon B Johnson Space Ctr, Space & Life Sci Directorate, Houston, TX 77058 USA. Wyle Labs, Houston, TX USA. RP Dulchavsky, SA (reprint author), Detroit Receiving Hosp, Dept Surg, 4201 St Antoine, Detroit, MI 48201 USA. NR 13 TC 131 Z9 136 U1 0 U2 6 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0022-5282 J9 J TRAUMA JI J. Trauma-Injury Infect. Crit. Care PD FEB PY 2001 VL 50 IS 2 BP 201 EP 204 DI 10.1097/00005373-200102000-00003 PG 4 WC Critical Care Medicine; Surgery SC General & Internal Medicine; Surgery GA 404WL UT WOS:000167125000004 PM 11242282 ER PT J AU DellaCorte, C AF DellaCorte, C TI February, a time to ... 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 FEB PY 2001 VL 57 IS 2 BP 3 EP 3 PG 1 WC Engineering, Mechanical SC Engineering GA 402EM UT WOS:000166973100001 ER PT J AU Cruikshank, DP AF Cruikshank, DP TI Linking meteorites with their parent bodies SO METEORITICS & PLANETARY SCIENCE LA English DT Editorial Material C1 NASA, Ames Res Ctr, Astrophys Branch, Moffett Field, CA 94035 USA. RP Cruikshank, DP (reprint author), NASA, Ames Res Ctr, Astrophys Branch, Moffett Field, CA 94035 USA. NR 3 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 USA SN 0026-1114 J9 METEORIT PLANET SCI JI Meteorit. Planet. Sci. PD FEB PY 2001 VL 36 IS 2 BP 192 EP 193 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 414EK UT WOS:000167652800002 ER PT J AU Taylor, LA Pieters, C Keller, LP Morris, RV McKay, DS Patchen, A Wentworth, S AF Taylor, LA Pieters, C Keller, LP Morris, RV McKay, DS Patchen, A Wentworth, S TI The effects of space weathering on Apollo 17 mare soils: Petrographic and chemical characterization SO METEORITICS & PLANETARY SCIENCE LA English DT Article ID DIGITAL-IMAGING PETROGRAPHY; LUNAR; MOON AB The lunar soil characterization consortium, a group of lunar-sample and remote-sensing scientists, has undertaken the extensive task of characterization of the finest fractions of lunar soils, with respect to their mineralogical and chemical makeup. These compositional data form the basis for integration and modeling with the reflectance spectra of these same soil fractions. This endeavor is aimed at deciphering the effects of space weathering of soils on airless bodies with quantification of the links between remotely sensed reflectance spectra and composition. A beneficial byproduct is an understanding of the complexities involved in the formation of lunar soil. Several significant findings have been documented in the study of the <45 m size fractions of selected Apollo 17 mare soils. As grain size decreases, the abundance of agglutinitic glass increases, as does the plagioclase, whereas the other minerals decrease. The composition of the agglutinitic glass is relatively constant for all size fractions, being more feldspathic than any of the bulk compositions; notably, TiO2 is substantially depleted in the agglutinitic glass. However, as grain size decreases, the bulk composition of each size fraction continuously changes, becoming more Al-rich and Fe-poor, and approaches the composition of the agglutinitic glasses. Between the smallest grain sizes ( 10-20 and <10 m), the I-S/FeO values (amount of total iron present as nanophase Fe-0) increase by greater than 100% (>2x), whereas the abundance of agglutinitic glass increases by only 10-15%. This is evidence for a large contribution from surface-correlated nanophase Fe-0 to the I-S/FeO values, particularly in the <10 m size fraction. The surface nanophase Fe-0 is present largely as vapor-deposited patinas on the surfaces of almost every particle of the mature soils, and to a lesser degree for the immature soils (Keller ef nl., 1999a). It is reasoned that the vapor-deposited patinas may have far greater effects upon reflectance spectra of mare soils than the agglutinitic Fe-0. C1 Univ Tennessee, Planetary Geosci Inst, Knoxville, TN 37996 USA. Brown Univ, Providence, RI 02912 USA. NASA, Lyndon B Johnson Space Ctr, Earth Sci & Solar Syst Explorat Div, Houston, TX 77058 USA. Lockheed Martin Space Operat Co, Houston, TX 77058 USA. RP Taylor, LA (reprint author), Univ Tennessee, Planetary Geosci Inst, Knoxville, TN 37996 USA. NR 47 TC 39 Z9 44 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 FEB PY 2001 VL 36 IS 2 BP 285 EP 299 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 414EK UT WOS:000167652800010 ER PT J AU Fabian, AC Mushotzky, RF Nulsen, PEJ Peterson, JR AF Fabian, AC Mushotzky, RF Nulsen, PEJ Peterson, JR TI On the soft X-ray spectrum of cooling flows SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE galaxies : clusters : general; cooling flows; X-rays : galaxies ID THERMAL CONDUCTION; GALAXY FORMATION; HEAT-CONDUCTION; CLUSTERS; M87; HALOS; CORE AB Strong evidence for cooling flows has been found in low-resolution X-ray imaging and spectra of many clusters of galaxies. However, high-resolution X-ray spectra of several clusters from the Reflection Grating Spectrometer on XMM-Newton now show a soft X-ray spectrum inconsistent with a simple cooling flow. The main problem is a lack of the emission lines expected from gas cooling below 1-2 keV. Lines from gas at about 2-3 keV are observed, even in a high-temperature cluster such as A1835, indicating that gas is cooling down to about 2-3 keV, but is not found at lower temperatures. Here we discuss several solutions to the problem: heating, mixing, differential absorption and inhomogeneous metallicity. Continuous or sporadic heating creates further problems, including the targeting of the heat at the cooler gas and also the high total energy required. So far there is no clear observational evidence for widespread heating, or shocks, in cluster cores, except in radio lobes which occupy only part of the volume. Alternatively, if the metals in the intracluster medium are not uniformly spread but are clumped, then little line emission is expected from the gas cooling below 1 keV. The low-metallicity part cools without line emission, whereas the strengths of the soft X-ray lines from the metal-rich gas depend on the mass fraction of that gas and not on the abundance, since soft X-ray line emission dominates the cooling function below 2 keV. C1 Univ Cambridge, Inst Astron, Cambridge CB3 0HA, England. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Wollongong, Wollongong, NSW 2522, Australia. Columbia Univ, Astrophys Lab, New York, NY 10027 USA. RP Fabian, AC (reprint author), Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England. NR 47 TC 87 Z9 87 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 FEB PY 2001 VL 321 IS 1 BP L20 EP L24 DI 10.1046/j.1365-8711.2001.04285.x PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 405HD UT WOS:000167153200004 ER PT J AU Rodgers, SD Charnley, SB AF Rodgers, SD Charnley, SB TI Organic synthesis in the coma of Comet Hale-Bopp? SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE comets : general; comets : individual : Hale-Bopp ID ORION COMPACT RIDGE; ABSORPTION FEATURES; INTERSTELLAR ICES; CARBON-MONOXIDE; MU-M; MOLECULES; WATER; CHEMISTRY; HYAKUTAKE; METHANOL AB Several organic molecules have now been detected in the coma of Hale-Bopp. These species may either emanate from the nucleus, or, as has been suggested by Bockelee-Morvan et al., could be synthesized in the coma. We have modelled the gas phase chemistry which occurred in the coma of Hale-Bopp, concentrating on the observed organic molecules HCOOH, HCOOCH3, HC3N and CH3CN. We find that gas phase chemical reactions are unable to synthesize the observed abundances of these molecules, so all these species are most probably present in the nuclear ice. We briefly discuss the implications of this result for the connection between cometary and interstellar ices. C1 NASA, Div Space Sci, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Rodgers, SD (reprint author), NASA, Div Space Sci, Ames Res Ctr, MS 245-3, Moffett Field, CA 94035 USA. RI Charnley, Steven/C-9538-2012 NR 40 TC 44 Z9 44 U1 0 U2 4 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 FEB 1 PY 2001 VL 320 IS 4 BP L61 EP L64 DI 10.1046/j.1365-8711.2001.04208.x PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 405QX UT WOS:000167171500003 ER PT J AU Shepherd, JM Ferrier, BS Ray, PS AF Shepherd, JM Ferrier, BS Ray, PS TI Rainfall morphology in Florida convergence zones: A numerical study SO MONTHLY WEATHER REVIEW LA English DT Article ID MACROSCOPIC ENTRAINMENT PROCESSES; SIMULATED CUMULUS ENSEMBLE; SOUTH FLORIDA; DEEP CONVECTION; THUNDERSTORM INITIATION; RADAR OBSERVATIONS; SQUALL-LINE; SEA BREEZES; GUST FRONT; LIFE-CYCLE AB Central Florida is the ideal test laboratory for studying convergence zone-induced convection. The region regularly experiences sea-breeze fronts and rainfall-induced outflow boundaries. The focus of this study is convection associated with the commonly occurring convergence zone established by the interaction of the sea-breeze front and an outflow boundary. Previous studies have investigated mechanisms primarily affecting storm initiation by such convergence zones. Pew have focused on rainfall morphology. yet these storms contribute a significant amount of precipitation to the annual rainfall budget. Low-level convergence and midtropospheric moisture have been shown to be correlated with rainfall amounts in Florida. Using 2D and 3D numerical simulations, the roles of low-level convergence and midtropospheric moisture in rainfall evolution are examined. The results indicate that area- and time-averaged, vertical moisture flux (VMF) at the sea-breeze front-outflow convergence zone is directly and linearly proportional to initial condensation rates. A similar relationship exists between VMF and initial rainfall. The VME which encompasses depth and magnitude of convergence. is better correlated to initial rainfall production than surface moisture convergence. This extends early observational studies that linked rainfall in Florida to surface moisture convergence. The amount and distribution of midtropospheric moisture affects how much rainfall associated with secondary cells develop. Rainfall amount and efficiency varied significantly over an observable range of relative humidities in the 850-500-mb layer even though rainfall evolution was similar during the initial or "first cell" period. Rainfall variability was attributed to drier midtropospheric environments inhibiting secondary cell development through entrainment effects. Observationally. a 850-500-mb moisture structure exhibits wider variability than lower-level moisture, which is virtually always present in Florida. A likely consequence of the variability in 850-500-mb moisture is a stronger statistical correlation to rainfall as noted in previous observational studies. The VMF at convergence zones is critical in determining rainfall in the initial stage of development but plays a decreasing role in rainfall evolution as the system matures. The midtropospheric moisture (e.g., environment) plays an increasing role in rainfall evolution as the system matures. This suggests the need to improve measurements of depth and magnitude of convergence and midtropospheric moisture distribution. It also highlights that the influence of the environment needs to be better represented in convertive parameterizations of larger-scale models to account for entrainment effects. C1 NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. Natl Ctr Environm Predict, Environm Modeling Ctr, Washington, DC USA. Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. RP Shepherd, JM (reprint author), NASA, Goddard Space Flight Ctr, Atmospheres Lab, Greenbelt, MD 20771 USA. NR 59 TC 19 Z9 19 U1 3 U2 12 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD FEB PY 2001 VL 129 IS 2 BP 177 EP 197 DI 10.1175/1520-0493(2001)129<0177:RMIFCZ>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 403RV UT WOS:000167057000001 ER PT J AU Stern, SA Weissman, PR AF Stern, SA Weissman, PR TI Rapid collisional evolution of comets during the formation of the Oort cloud SO NATURE LA English DT Article ID OUTER SOLAR-SYSTEM; DYNAMICAL EVOLUTION; KUIPER-BELT; PLANETESIMALS; ACCRETION; ASTEROIDS AB The Oort cloud(1) of comets was formed by the ejection of icy planetesimals from the region of giant planets-Jupiter, Saturn, Uranus and Neptune-during their formation(2). Dynamical simulations(3,4) have previously shown that comets reach the Oort cloud only after being perturbed into eccentric orbits that result in close encounters with the giant planets, which then eject them to distant orbits about 10(4) to 10(5) AU from the Sun (1 AU is the average Earth-Sun distance). All of the Oort cloud models constructed until now simulate its formation using only gravitational effects; these include the influence of the Sun, the planets and external perturbers such as passing stars and Galactic tides. Here we show that physical collisions between comets and small debris play a fundamental and hitherto unexplored role throughout most of the ejection process. For standard models of the protosolar nebula (starting with a minimum-mass nebula) we rnd that collisional evolution of comets is so severe that their erosional lifetimes are much shorter than the timescale for dynamical ejection. It therefore appears that collisions will prevent most comets escaping from most locations in the region of the giant planets until the disk mass there declines sufficiently that the dynamical ejection timescale is shorter than the collisional lifetime. One consequence is that the total mass of comets in the Oort cloud may be less than currently believed. C1 SW Res Inst, Dept Space Studies, Boulder, CO 80302 USA. CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. RP Stern, SA (reprint author), SW Res Inst, Dept Space Studies, Boulder, CO 80302 USA. EM astern@swri.edu NR 27 TC 52 Z9 53 U1 0 U2 0 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD FEB 1 PY 2001 VL 409 IS 6820 BP 589 EP 591 DI 10.1038/35054508 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 397JJ UT WOS:000166692300035 PM 11214311 ER PT J AU Pepper, PN Girard, TL Stapanian, MA AF Pepper, PN Girard, TL Stapanian, MA TI An apparatus for preparing benthic samples aboard ship SO NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT LA English DT Editorial Material AB We describe a safe and effective apparatus for washing and reducing the volume of benthic samples collected by grab samplers aboard ship. The sample is transferred directly from the dredge to the apparatus and then washed with water pumped through pipes in the apparatus and from onboard hoses. Wastewater and materials smaller than 0.541 mm in diameter are washed overboard. Larger materials, including benthic organisms, collect on an upper 0.64-cm screen and on a lower 30-mm-mesh stainless steel bolt cloth. A collection jar is screwed into the bottom of the apparatus. Therefore, transfer of sample material from the apparatus to the jar is quick and easy. This apparatus has several advantages for use aboard ship over others described in the literature, especially in rough seas, in cold weather, and at night. The apparatus provides a safe and convenient platform for washing and reducing samples, and samples can be prepared while the vessel is traveling at full speed. C1 US Geol Survey, Lake Erie Biol Stn, NASA, Plumb Brook Res Ctr, Sandusky, OH 44870 USA. US Geol Survey, Cheboygan, MI 49720 USA. RP Stapanian, MA (reprint author), US Geol Survey, Lake Erie Biol Stn, NASA, Plumb Brook Res Ctr, 6100 Columbus Ave, Sandusky, OH 44870 USA. OI Stapanian, Martin/0000-0001-8173-4273 NR 8 TC 0 Z9 0 U1 0 U2 1 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 USA SN 0275-5947 J9 N AM J FISH MANAGE JI North Am. J. Fish Manage. PD FEB PY 2001 VL 21 IS 1 BP 249 EP 252 DI 10.1577/1548-8675(2001)021<0249:AAFPBS>2.0.CO;2 PG 4 WC Fisheries SC Fisheries GA 529FH UT WOS:000174289000026 ER PT J AU Berejikian, BA Tezak, EP Schroder, SL AF Berejikian, BA Tezak, EP Schroder, SL TI Reproductive behavior and breeding success of captively reared chinook salmon SO NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT LA English DT Editorial Material ID ONCORHYNCHUS-KISUTCH; SOCKEYE-SALMON; ATLANTIC SALMON; MALE-DOMINANCE; COMPETITION; WILD; COHO; NERKA; SELECTION; HATCHERY AB Release of captively reared adults is one of several strategies currently being used to maintain imperiled populations of chinook salmon Oncorhynchus tshawytscha in the Pacific Northwest. This study evaluated the breeding behavior and success of captively reared chinook salmon released at maturity into a controlled-flow stream channel. Female egg deposition was 49.5%, which is much lower than that reported for wild populations, but egg-to-fry survival was 62.5%. Females abandoned 409,, of the nests they constructed, and males were often absent during the female's nest construction, The underlying causes of these presumed behavioral deficiencies might have limited the breeding success of the population. The efficacy of adult release strategies should be assessed within the context of other potential release options, keeping in mind the objectives of the individual program. Under current culture practices, the reproductive success of captively reared chinook salmon that are released as adults may be less than that of wild salmon. C1 Natl Marine Fisheries Serv, Resource Enhancement & Utilizat Technol Div, NW Fisheries Sci Ctr, Manchester Res Stn, Manchester, WA 98353 USA. Washington Dept Fish & Wildlife, Olympia, WA 98501 USA. RP Berejikian, BA (reprint author), Natl Marine Fisheries Serv, Resource Enhancement & Utilizat Technol Div, NW Fisheries Sci Ctr, Manchester Res Stn, POB 130, Manchester, WA 98353 USA. NR 30 TC 24 Z9 24 U1 2 U2 9 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 USA SN 0275-5947 J9 N AM J FISH MANAGE JI North Am. J. Fish Manage. PD FEB PY 2001 VL 21 IS 1 BP 255 EP 260 DI 10.1577/1548-8675(2001)021<0255:RBABSO>2.0.CO;2 PG 6 WC Fisheries SC Fisheries GA 529FH UT WOS:000174289000028 ER PT J AU Ramsey, B Sharma, DP Austin, R Gostilo, V Ivanov, V Loupilov, A Sokolov, A Sipila, H AF Ramsey, B Sharma, DP Austin, R Gostilo, V Ivanov, V Loupilov, A Sokolov, A Sipila, H TI Preliminary performance of CdZnTe imaging detector prototypes SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 11th International Workshop on Room-Temperature Semiconductor X- and Gamma-Ray Detectors and Associated Electronics CY OCT 11-15, 1999 CL INT ATOM ENERGY AGCY HEADQUARTERS, VIENNA, AUSTRIA HO INT ATOM ENERGY AGCY HEADQUARTERS DE imaging arrays; pixel detectors AB The promise of good energy and spatial resolution coupled with high efficiency and near-room-temperature operation has fuelled a large international effort to develop cadmium-zinc-telluride (CdZnTe) for the hard-X-ray region. We present, here, preliminary results from our development of small-pixel imaging arrays fabricated on 5 x 5 x l-mm and 5 x 5 x 2-mm spectroscopy and discriminator-grade material. Each array has 16 (4 x 4) 0.65-mm gold readout pads on a 0.75-mm pitch, with each pad connected to a discrete preamplifier via a pulse-welded gold wire. Each array is mounted on a three-stage Peltier cooler and housed in an ion-pump-evacuated housing which also contains a hybrid micro-assembly for the 16 channels of electronics. We have investigated the energy resolution and approximate photopeak efficiency for each pixel at several energies and have used an ultra-fine beam X-ray generator to probe the performance at the pixel boundaries. Both arrays gave similar results and at an optimum temperature of - 20 degreesC we achieved between 2% and 3% full-width at half-maximum energy resolution at 60 keV and around 15% at 5.9 keV. We found that all the charge was contained within one pixel except very close to the pixels edge, where it would start to be shared with its neighbor. Even between pixels, all the charge would be appropriately shared with no apparently loss of efficiency or resolution. Full details of these measurements will be presented, together with their implications for future imaging-spectroscopy applications. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Balt Sci Instruments, LV-1005 Riga, Latvia. NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. Metorex Int Oy, FIN-02631 Espoo, Finland. RP Gostilo, V (reprint author), Balt Sci Instruments, Ganibu Dambis 26,POB 33, LV-1005 Riga, Latvia. NR 6 TC 3 Z9 3 U1 1 U2 4 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 FEB 1 PY 2001 VL 458 IS 1-2 BP 55 EP 61 DI 10.1016/S0168-9002(00)00851-2 PG 7 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 401UJ UT WOS:000166946400009 ER PT J AU Parnham, K Szeles, C Prettyman, TH Smith, M Stahle, C Parker, BH Wang, WL AF Parnham, K Szeles, C Prettyman, TH Smith, M Stahle, C Parker, BH Wang, WL TI Further studies on the modified two-terminal geometry for CdZnTe detectors SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 11th International Workshop on Room-Temperature Semiconductor X- and Gamma-Ray Detectors and Associated Electronics CY OCT 11-15, 1999 CL INT ATOM ENERGY AGCY HEADQUARTERS, VIENNA, AUSTRIA HO INT ATOM ENERGY AGCY HEADQUARTERS DE CdZnTe; gamma ray detector; CAPture (TM) technology; charge transport; modified electric field ID SEMICONDUCTOR RADIATION DETECTORS; CD0.8ZN0.2TE AB This paper will report on additional studies undertaken on a novel electrode geometry, referred to as CAPture(TM) technology, wherein the cathode is extended up the sides of a planar CdZnTe detector. The initial presentation of this development focused on a single geometry, and a simple mechanism was proposed to explain the improved performance. In this presentation, we will describe the results of further electric field and charge transport modeling as applied to this detector configuration, and also compare the calculated performance with experimental results. (C) 2001 Elsevier Science B.V. All rights reserved. C1 eV PROD, Saxonburg, PA 16056 USA. Univ Calif Los Alamos Natl Lab, Safeguards Sci & Technol Grp, Los Alamos, NM 87545 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Unisys Corp, Blue Bell, PA 19424 USA. RP Parnham, K (reprint author), eV PROD, 373 Saxonburg Blvd, Saxonburg, PA 16056 USA. OI Prettyman, Thomas/0000-0003-0072-2831 NR 7 TC 4 Z9 5 U1 1 U2 4 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 FEB 1 PY 2001 VL 458 IS 1-2 BP 334 EP 338 DI 10.1016/S0168-9002(00)00878-0 PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 401UJ UT WOS:000166946400047 ER PT J AU Tripathi, RK Wilson, JW Cucinotta, FA AF Tripathi, RK Wilson, JW Cucinotta, FA TI Medium modified two-body scattering amplitude from proton-nucleus total cross-sections SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS LA English DT Article AB Recently (R.K. Tripathi, J.W. Wilson. F.A. Cucinotta, Nucl. Instr. and Meth. B 145 (1998) 277: R.K. Tripathi, F.A. Cucinotta, J.W. Wilson, NASA-TP-1998-208438), we have extracted nucleon-nucleon (N-N) cross-sections in the medium directly from experiment. The in-medium N-N cross-sections form the basic ingredients of several heavy-ion scattering approaches including the coupled-channel approach developed at the NASA Langley Research Canter. Here, we investigate the ratio of real to imaginary part of the two-body scattering amplitude in the medium. These ratios are used in combination with the in-medium N-N cross-sections to calculate total proton-nucleus cross-sections. The agreement is excellent with the available experimental data, These cross-sections are needed for the radiation risk assessment of space missions. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Langley Res Ctr, Hampton, VA 23680 USA. NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Tripathi, RK (reprint author), NASA, Langley Res Ctr, Mail Stop 188B,8 W Taylor St, Hampton, VA 23680 USA. NR 16 TC 8 Z9 9 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-583X J9 NUCL INSTRUM METH B JI Nucl. Instrum. Methods Phys. Res. Sect. B-Beam Interact. Mater. Atoms PD FEB PY 2001 VL 173 IS 4 BP 391 EP 396 DI 10.1016/S0168-583X(00)00414-6 PG 6 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA 397WU UT WOS:000166721500001 PM 11878351 ER PT J AU Griffin, DW AF Griffin, DW TI Phase-shifting shearing interferometer SO OPTICS LETTERS LA English DT Article ID INTERFEROGRAMS AB A single-element phase-shifting interferometer has been developed based on the lateral shearing interferometer. This new interferometer requires no precise alignment, and the phase is continuously varied by changes in the voltage across a commercially available liquid-crystal phase retarder. (C) 2001 Optical Society of America. C1 NASA, Micrograv Fluid Phys Branch, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Griffin, DW (reprint author), NASA, Micrograv Fluid Phys Branch, Glenn Res Ctr, M-S 110-3,21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 7 TC 48 Z9 48 U1 0 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD FEB 1 PY 2001 VL 26 IS 3 BP 140 EP 141 DI 10.1364/OL.26.000140 PG 2 WC Optics SC Optics GA 398KH UT WOS:000166755300008 PM 18033529 ER PT J AU Weber, AL AF Weber, AL TI The sugar model: Catalysis by amines and amino acid products SO ORIGINS OF LIFE AND EVOLUTION OF THE BIOSPHERE LA English DT Article DE amine catalysis; amino acid catalysis; autocatalysis; formose reaction; molecular evolution; prebiotic synthesis; sugar chemistry ID EARLY EARTH; LIQUID-CHROMATOGRAPHY; PREBIOTIC SYNTHESIS; AQUEOUS-SOLUTION; ENERGY; GLYCERALDEHYDE; ATMOSPHERE; EVOLUTION; PHOTOCHEMISTRY; FORMALDEHYDE AB Ammonia and amines (including amino acids) were shown to catalyze the formation of sugars from formaldehyde and glycolaldehyde, and the subsequent conversion of sugars to carbonyl-containing products under the conditions studied (pH 5.5 and 50 degreesC). Sterically unhindered primary amines were better catalysts than ammonia, secondary amines, and sterically hindered primary amines (i.e. alpha -aminoisobutyric acid). Reactions catalyzed by primary amines initially consumed formaldehyde and glycolaldehyde about 15-20 times faster than an uncatalyzed control reaction. The amine-catalyzed reactions yielded aldotriose (glyceraldehyde), ketotriose (dihydroxyacetone), aldotetroses (erythrose and threose), ketotetrose (erythrulose), pyruvaldehyde, acetaldehyde, glyoxal, pyruvate, glyoxylate, and several unindentified carbonyl products. The concentrations of the carbonyl products, except pyruvate and ketotetrose, initially increased and then declined during the reaction, indicating their ultimate conversion to other products (like larger sugars or pyruvate). The uncatalyzed control reaction yielded no pyruvate or glyoxylate, and only trace amounts of pyruvaldehyde, acetaldehyde and glyoxal. In the presence of 15 mM catalytic primary amine, such as alanine, the rates of triose and pyruvaldehyde of synthesis were about 15-times and 1200-times faster, respectively, than the uncatalyzed reaction. Since previous studies established that alanine is synthesized from glycolaldehyde and formaldehyde via pyruvaldehyde as its direct precursor, the demonstration that the alanine catalyzes the conversion of glycolaldehyde and formaldehyde to pyruvaldehyde indicates that this synthetic pathway is capable of autocatalysis. The relevance of this synthetic process, named the Sugar Model, to the origin of life is discussed. C1 NASA, Ames Res Ctr, SETI Inst, Moffett Field, CA 94035 USA. RP Weber, AL (reprint author), NASA, Ames Res Ctr, SETI Inst, Mail Stop 239-4, Moffett Field, CA 94035 USA. NR 49 TC 60 Z9 63 U1 2 U2 43 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0169-6149 J9 ORIGINS LIFE EVOL B JI Orig. Life Evol. Biosph. PD FEB-APR PY 2001 VL 31 IS 1-2 BP 71 EP 86 DI 10.1023/A:1006750423942 PG 16 WC Biology SC Life Sciences & Biomedicine - Other Topics GA 415TC UT WOS:000167737900005 PM 11296525 ER PT J AU Smialek, JL AF Smialek, JL TI The effect of hydrogen annealing on the impurity content of alumina-forming alloys SO OXIDATION OF METALS LA English DT Article DE impurities; sulfur; segregation; hydrogen annealing; Al(2)O(3) scale adhesion ID FE-CR-AL; GRAIN-BOUNDARY SEGREGATION; OXIDE SCALE ADHERENCE; SULFUR REMOVAL; OXIDATION BEHAVIOR; ELEMENT ADDITIONS; GROWTH MECHANISMS; Y ALLOYS; MORPHOLOGY; DIFFUSION AB Previously, the effect of hydrogen annealing on increasing the adhesion of Al(2)O(3) scales had been related to the effective desulfurization that occurred during this process. The simultaneous reduction of other impurities has now been reexamined for up to 20 impurity elements, in the case of five different alloys (NiCrAl, FeCrAl, PWA 1480, Rene 142, and Rend N5). Hydrogen annealing produced measurable reductions in elemental concentration for B, C, Na, Mg, Si, P, K, Sr, or Sn in varying degrees for at least one and up to three of these alloys. However, no single element was I educed by hydrogen annealing for all the alloys except sulfur. In many cases spalling occurred at low levels of these other impurity, while in other cases the scales were adherent at high levels of the impurities. No impurity besides sulfur was strongly correlated with adhesion. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Smialek, JL (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 28 TC 17 Z9 17 U1 1 U2 9 PU SPRINGER/PLENUM PUBLISHERS PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0030-770X J9 OXID MET JI Oxid. Met. PD FEB PY 2001 VL 55 IS 1-2 BP 75 EP 86 DI 10.1023/A:1010325209121 PG 12 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA 425HL UT WOS:000168285100005 ER PT J AU Remington, RW Folk, CL McLean, JP AF Remington, RW Folk, CL McLean, JP TI Contingent attentional capture or delayed allocation of attention? SO PERCEPTION & PSYCHOPHYSICS LA English DT Article ID ABRUPT VISUAL ONSETS; SELECTIVE ATTENTION; FOCUSED ATTENTION; PERCEPTUAL LOAD; SEARCH; SINGLETONS; VOLUNTARY; OBJECTS; COLOR; LOCUS AB Under certain circumstances, external stimuli will elicit an involuntary shift of spatial attention, referred to as attentional capture. According to the contingent involuntary orienting account (Folk, Remington, & Johnston, 1992), capture is conditioned by top-down factors that set attention to respond involuntarily to stimulus properties relevant to one's behavioral goals. Evidence for this comes from spatial cuing studies showing that a spatial cuing effect is observed only when cues have goal-relevant properties. Here, we examine alternative, decision-level explanations of the spatial cuing effect that attribute evidence of capture to postpresentation delays in the voluntary allocation of attention, rather than to on-line involuntary shifts in direct response to the cue. In three spatial cuing experiments, delayed-allocation accounts were tested by examining whether items at the cued location were preferentially processed. The experiments provide evidence that costs and benefits in spatial cuing experiments do reflect the on-line capture of attention. The implications of these results for models of attentional control are discussed. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Villanova Univ, Villanova, PA 19085 USA. Univ Queensland, St Lucia, Qld 4067, Australia. RP Remington, RW (reprint author), NASA, Ames Res Ctr, MS262-4, Moffett Field, CA 94035 USA. RI Martin Arevalo, Elisa/L-4472-2014 OI Martin Arevalo, Elisa/0000-0002-4546-6440 NR 26 TC 54 Z9 57 U1 2 U2 5 PU PSYCHONOMIC SOC INC PI AUSTIN PA 1710 FORTVIEW RD, AUSTIN, TX 78704 USA SN 0031-5117 J9 PERCEPT PSYCHOPHYS JI Percept. Psychophys. PD FEB PY 2001 VL 63 IS 2 BP 298 EP 307 DI 10.3758/BF03194470 PG 10 WC Psychology; Psychology, Experimental SC Psychology GA 413TL UT WOS:000167628000010 PM 11281104 ER PT J AU Bailey, K Beck, R Frohn, R Pleva, D Plumer, D Price, M Krute, R Ramos, C South, R AF Bailey, K Beck, R Frohn, R Pleva, D Plumer, D Price, M Krute, R Ramos, C South, R TI Native American Remote Sensing Distance Education Prototype (NARSDEP) SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article AB The purpose of the Native American Remote Sensing Distance Education Prototype (NARSDEP) is to provide remote sensing classes to students of the Leech Lake Tribal College (LLTC) and tribal government representatives in cooperation with the University of Cincinnati (UC). The Leech Lake Indian Reservation is located in a rural part of northern Minnesota. High-speed Internet access is very limited in this community. The distance-learning program to be conducted by LLTC and the uc is the central component of the Gateway2Earth: OhioView Pilot in cooperation with the NASA Glenn Research Center and the USGS EROS Data Center. Gateway2Earth is a national consortium of universities, colleges, schools, federal, tribal, state, and local governments and industry designed to promote the development of the satellite remote sensing industry in the United States through improved access to geospatial data and technology for education and research. NARSDEP represents the beginning of the Native American educational and research component of Gateway2Earth. C1 NARSINC, Cincinnati, OH 45239 USA. Univ Cincinnati, Dept Geog, Cincinnati, OH 45221 USA. Univ Illinois, Grad Sch Lib & Informat Sci, Champaign, IL 61820 USA. NASA, Glenn Res Ctr, Networking & Telecommun Branch, Cleveland, OH 44135 USA. NASA, Glenn Res Ctr, Cent Proc Syst Operat Branch, Cleveland, OH 44135 USA. Leech Lake Tribal Coll, Dept Sci, Cass Lake, MN 56633 USA. NASA, Glenn Res Ctr, Satellite Networks & Commun Branch, Cleveland, OH 44135 USA. RP Bailey, K (reprint author), NARSINC, 3355 Blue Rock Rd, Cincinnati, OH 45239 USA. NR 9 TC 0 Z9 0 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 FEB PY 2001 VL 67 IS 2 BP 193 EP 197 PG 5 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA 399YZ UT WOS:000166843000008 ER PT J AU Hughes, TJR Mazzei, L Oberai, AA Wray, AA AF Hughes, TJR Mazzei, L Oberai, AA Wray, AA TI The multiscale formulation of large eddy simulation: Decay of homogeneous isotropic turbulence SO PHYSICS OF FLUIDS LA English DT Article ID NUMERICAL-SIMULATION; MODEL AB The variational multiscale method is applied to the large eddy simulation (LES) of homogeneous, isotropic flows and compared with the classical Smagorinsky model, the dynamic Smagorinsky model, and direct numerical simulation (DNS) data. Overall, the multiscale method is in better agreement with the DNS data than both the Smagorinsky model and the dynamic Smagorinsky model. The results are somewhat remarkable when one realizes that the multiscale method is almost identical to the Smagorinsky model (the least accurate model!) except for removal of the eddy viscosity from a very small percentage of the lowest modes. (C) 2001 American Institute of Physics. C1 Stanford Univ, Div Mech & Computat, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Stanford Univ, Div Mech & Computat, WF Durand Bldg, Stanford, CA 94305 USA. EM hughes@am-sum2.stanford.edu NR 22 TC 218 Z9 221 U1 1 U2 11 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 1070-6631 EI 1089-7666 J9 PHYS FLUIDS JI Phys. Fluids PD FEB PY 2001 VL 13 IS 2 BP 505 EP 512 DI 10.1063/1.1332391 PG 8 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 393PC UT WOS:000166478000014 ER PT J AU Gibson, EK McKay, DS Thomas-Keprta, KL Wentworth, SJ Westall, F Steele, A Romanek, CS Bell, MS Toporski, J AF Gibson, EK McKay, DS Thomas-Keprta, KL Wentworth, SJ Westall, F Steele, A Romanek, CS Bell, MS Toporski, J TI Life on Mars: evaluation of the evidence within Martian meteorites ALH84001, Nakhla, and Shergotty SO PRECAMBRIAN RESEARCH LA English DT Review ID POLYCYCLIC AROMATIC-HYDROCARBONS; AUTOPOIETIC SELF-REPRODUCTION; ENDOGENOUS AMINO-ACIDS; ISOTOPIC COMPOSITIONS; LOW-TEMPERATURE; PAST LIFE; PETROLOGIC EVIDENCE; LIQUID WATER; ALLAN-HILLS-84001; ORIGIN AB Analyses both support and are in opposition to the hypothesis that the Martian meteorite ALH84001 contains evidence for possible biogenic activity on Mars. New observations in two additional Martian meteorites, Nakhla (1.3 Ga old) and Shergotty (300-165 Ma old) indicate possible biogenic features. Features in the three Martian meteorites compare favorably with the accepted criteria for terrestrial microfossils and evidence for early life on the Earth. There is strong evidence for the presence of indigenous reduced carbon, biogenic magnetite, and the low-temperature formation of carbonate globules. The morphological similarities between terrestrial microfossils, biofilms, and the features found in the three Martian meteorites are intriguing but have not been conclusively proven. Every investigation must recognize the possibility of terrestrial contamination of the meteorites, whether or not the meteorites are Martian. The search for evidence of ancient life in Martian meteorites has emphasized the difficulties confronting the scientific community with the respect to the positive identification of evidence of past biogenic activity. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. Lockheed Martin Corp, Houston, TX 77058 USA. Univ Portsmouth, Portsmouth, Hants, England. Univ Georgia, Savannah River Ecol Lab, Aiken, SC 29802 USA. RP Gibson, EK (reprint author), NASA, Lyndon B Johnson Space Ctr, SN2, Houston, TX 77058 USA. NR 112 TC 48 Z9 50 U1 7 U2 35 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-9268 J9 PRECAMBRIAN RES JI Precambrian Res. PD FEB 1 PY 2001 VL 106 IS 1-2 BP 15 EP 34 DI 10.1016/S0301-9268(00)00122-4 PG 20 WC Geosciences, Multidisciplinary SC Geology GA 402TQ UT WOS:000167004600003 ER PT J AU Offenberg, JD Fixsen, DJ Rauscher, BJ Forrest, WJ Hanisch, RJ Mather, JC McKelvey, ME McMurray, RE Nieto-Santisteban, MA Pipher, JL Sengupta, R Stockman, HS AF Offenberg, JD Fixsen, DJ Rauscher, BJ Forrest, WJ Hanisch, RJ Mather, JC McKelvey, ME McMurray, RE Nieto-Santisteban, MA Pipher, JL Sengupta, R Stockman, HS TI Validation of up-the-ramp sampling with cosmic-ray rejection on infrared detectors SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article AB We examine cosmic-ray rejection methodology on data collected from InSb and Si: As detectors. The application of an up-the-ramp sampling technique with cosmic-ray identification and mitigation is the focus of this study. This technique is valuable for space-based observatories which are exposed to high-radiation environments. We validate the up-the-ramp approach on radiation-test data sets with InSb and Si: As detectors which were generated for SIRTF. The up-the-ramp sampling method studied in this paper is over 99.9% effective at removing cosmic rays and preserves the structure and photometric quality of the image to well within the measurement error. C1 Raytheon ITSS, Lanham, MD 20706 USA. NASA, Goddard Space Flight Ctr, Astron & Solar Phys Lab, Greenbelt, MD 20771 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Rochester, Dept Phys & Astron, Rochester, NY 14627 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Offenberg, JD (reprint author), Raytheon ITSS, 4500 Forbes Blvd, Lanham, MD 20706 USA. NR 9 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 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD FEB PY 2001 VL 113 IS 780 BP 240 EP 254 DI 10.1086/318615 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 397TK UT WOS:000166713300013 ER PT J AU Ranson, KJ Sun, G Kharuk, VI Kovacs, K AF Ranson, KJ Sun, G Kharuk, VI Kovacs, K TI Characterization of forests in Western Sayani Mountains, Siberia from SIR-C SAR data SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SYNTHETIC-APERTURE RADAR; C/X-SAR; VEGETATION CHARACTERIZATION; TOPOGRAPHIC CORRECTION; CLASSIFICATION; IMAGERY; TERRAIN; MODEL AB This paper examines the use of spaceborne radar data 50 map forest types and logging in the mountainous Western Sayani area in central Siberia. L- and C- band HH-, HV-, and VV-polarized images from the Shuttle Imaging Radar-C instrument were used in the study. Techniques to reduce topographic effects in the radar images were investigated. These included radiometric correction using illumination angle inferred from a digital elevation model and reducing apparent effects of topography through band ratios. For-est classification was performed after terrain correction utilizing typical supervised techniques and principal component analyses. An ancillary data set of local elevations was also used to improve the forest classification. Map accuracy for each technique was estimated for training sites based on Russian forestry maps, satellite imagery, and field measurements. The results indicate that it is necessary to correct for topography when attempting to classify forests in mountainous terrain. Radiometric correction based on a digital elevation model improved classification results brit required reducing the synthetic aperture radar resolution, to match the digital elevation model. Using ratios of synthetic aperture radar channels that include cross-polarization improved classification and had the advantages of eliminating the need for a digital elevation model and preserving the full resolution of the synthetic aperture radar data. (C) Elsevier Science Inc., 2001. All Rights Reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Geog, College Pk, MD 20742 USA. Academgorodok, VN Sukachev Inst Forest, Krasnoyarsk, Russia. Sci Syst & Applicat Inc, Lanham, MD USA. RP Ranson, KJ (reprint author), NASA, Goddard Space Flight Ctr, Code 923, Greenbelt, MD 20771 USA. RI Ranson, Kenneth/G-2446-2012 OI Ranson, Kenneth/0000-0003-3806-7270 NR 27 TC 19 Z9 20 U1 0 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 FEB PY 2001 VL 75 IS 2 BP 188 EP 200 DI 10.1016/S0034-4257(00)00166-8 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 396LC UT WOS:000166637000004 ER PT J AU Ranson, KJ Sun, G Knox, RG Levine, ER Weishampel, JF Fifer, ST AF Ranson, KJ Sun, G Knox, RG Levine, ER Weishampel, JF Fifer, ST TI Northern forest ecosystem dynamics using coupled models and remote sensing SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID RADAR BACKSCATTER; BOREAL FORESTS; SAR IMAGES; BIOMASS; CLASSIFICATION; MULTIFREQUENCY; TEMPERATURE; SIMULATION; ALASKA; MAINE AB Forest ecosystem dynamics modeling, remote sensing data analysis, ann a geographical information system (GIS) were used together to determine the possible growth and development of a northern forest in Maine, USA. Field measurements and airborne synthetic aperture radar (SAR) data were used to produce maps of forest cover type and above ground biomass. These forest attribute maps derived with remote sensing data, along with a conventional soils map, were used to identify the initial conditions for forest ecosystem model simulations. Using this information along with ecosystem model results enabled the development of predictive maps of forest development The results obtained were consistent with observed forest conditions and expected successional trajectories. The study demonstrated that ecosystem models might be used in a spatial context when parametrized and used with georeferenced data sets. (C) Elsevier Science Inc., 2001. All Rights Reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland, Dept Geog, College Pk, MD 20742 USA. Univ Cent Florida, Dept Biol, Orlando, FL 32816 USA. Raytheon ITSS, Lanham, MD USA. RP Ranson, KJ (reprint author), NASA, Goddard Space Flight Ctr, Code 923, Greenbelt, MD 20771 USA. RI Knox, Robert/E-9657-2011; Ranson, Kenneth/G-2446-2012 OI Ranson, Kenneth/0000-0003-3806-7270 NR 34 TC 11 Z9 11 U1 2 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 FEB PY 2001 VL 75 IS 2 BP 291 EP 302 DI 10.1016/S0034-4257(00)00174-7 PG 12 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA 396LC UT WOS:000166637000012 ER PT J AU Ng, D Fralick, G AF Ng, D Fralick, G TI Use of a multiwavelength pyrometer in several elevated temperature aerospace applications SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB A multiwavelength pyrometer was developed for applications unique to aerospace environments. It was shown to be a useful and versatile technique for measuring temperature, even when the emissivity is unknown. It has also been used to measure the surface temperatures of ceramic zircornia thermal barrier coatings and alumina. The close agreement between pyrometer and thin film thermocouple temperatures provided an independent check. Other applications of the multiwavelength pyrometer are simultaneous surface and bulk temperature measurements of a transparent material, and combustion gas temperature measurement using a special probe interfaced to the multiwavelength pyrometer via an optical fiber. The multiwavelength pyrometer determined temperature by transforming the radiation spectrum in a broad wavelength region to produce a straight line (in a certain spectral region), whose intercept in the vertical axis gives the temperature. Implicit in a two-color pyrometer is the assumption of wavelength independent emissivity. Though the two data points of a two-color pyrometer similarly processed would result immediately in a similar straight line to give the unknown temperature, the two-color pyrometer lacks the greater data redundancy of the multiwavelength pyrometer, which enables it to do so with improved accuracy. It also confirms that emissivity is indeed wavelength independent, as evidenced by a multitude of the data lying on a simple straight line. The multiwavelength pyrometer was also used to study the optical transmission properties of a nanostructured material from which a quadratic exponential functional frequency dependence of its spectral transmission was determined. Finally, by operating the multiwavelength pyrometer in a very wide field of view mode, the surface temperature distribution of a large hot surface was obtained through measurement of just a single radiation spectrum. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Ng, D (reprint author), NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. NR 15 TC 42 Z9 46 U1 2 U2 19 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 FEB PY 2001 VL 72 IS 2 BP 1522 EP 1530 DI 10.1063/1.1340558 PG 9 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA 397JA UT WOS:000166688500047 ER PT J AU Ramaswamy, V Chanin, ML Angell, J Barnett, J Gaffen, D Gelman, M Keckhut, P Koshelkov, Y Labitzke, K Lin, JJR O'Neill, A Nash, J Randel, W Rood, R Shine, K Shiotani, M Swinbank, R AF Ramaswamy, V Chanin, ML Angell, J Barnett, J Gaffen, D Gelman, M Keckhut, P Koshelkov, Y Labitzke, K Lin, JJR O'Neill, A Nash, J Randel, W Rood, R Shine, K Shiotani, M Swinbank, R TI Stratospheric temperature trends: Observations and model simulations SO REVIEWS OF GEOPHYSICS LA English DT Review ID QUASI-BIENNIAL OSCILLATION; ANTARCTIC OZONE HOLE; 11-YEAR SOLAR-CYCLE; GENERAL-CIRCULATION MODEL; NORTHERN-HEMISPHERE WINTER; SEA-SURFACE TEMPERATURE; DOUBLED CO2 CLIMATE; MIDDLE ATMOSPHERE; LONG-TERM; WATER-VAPOR AB Trends and variations in global stratospheric temperatures are an integral part of the changes occurring in the Earth's climate system. Data sets for analyzing long-term (a decade and more) changes in the stratospheric temperatures consist of radiosonde, satellite, lidar, and rocketsonde measurements; meteorological analyses based on radiosonde and/or satellite data; and products based on assimilating observations using a general circulation model. Each of these contain varying degrees of uncertainties that influence the interpretation and significance of trends, We review the long-term trends from approximately the mid-1960s to the mid-1990s period. The stratosphere: has, in general, undergone considerable cooling over the past 3 decades. At northern midlatitudes the lower stratosphere (similar to 16-21 km) cooling over the 1979-1994 period is strikingly coherent among the various data sets with regard to magnitude and statistical significance. A substantial cooling occurs in the polar lower stratosphere during winter-spring; however, there is a large dynamical variability in the northern polar region. The vertical profile of the annual-mean stratospheric temperature change in the northern midlatitudes over the 1979-1994 period is robust among the different data sets, with similar to0.75 K/decade cooling in the similar to 20- to 35-km region and increasing cooling above (e.g., similar to2.5 K/decade at 50 km). Model investigations into the cause or causes of the observed temperature trends are also reviewed, Simulations based on the known changes in species' concentrations indicate that the depiction of lower stratospheric ozone is the major radiative factor in accounting for the 1979-1990 cooling trend in the global, annual-mean lower stratosphere (similar to0.5 to 0.6 K/decade), with a substantially lesser contribution by the well-mixed greenhouse gases. Ozone loss is also an important causal factor in the latitude-month pattern of the lower stratospheric cooling trend. Uncertainties arise due to incomplete knowledge of the vertical profile of ozone loss near the tropopause. In the middle and upper stratosphere, both well-mixed greenhouse gases and ozone changes contribute in an important manner to the cooling, but model simulations underestimate the observed decadal-scale trend. While there is a lack of reliable information on water vapor changes over the 1980s decade, satellite measurements in the early to middle 1990s indicate increases in water vapor that could be a significant contributor to the cooling of the global lower stratosphere. C1 Princeton Univ, NOAA, Geophys Fluid Dynam Lab, Princeton, NJ 08452 USA. CNRS, Serv Aeron, F-91371 Verrieres Le Buisson, France. NOAA, Air Resources Lab, Silver Spring, MD 20910 USA. Univ Oxford, Dept Atmospher Phys, Oxford OX1 3PU, England. Natl Ctr Environm Predict, Climate Predict Ctr, Washington, DC 20233 USA. Cent Aerol Observ, Moscow, Russia. Free Univ Berlin, Inst Meteorol, D-1000 Berlin 41, Germany. Univ Reading, Dept Meteorol, Reading RG6 6BB, Berks, England. UK Meteorol Off, Bracknell RG12 2SZ, Berks, England. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. Hokkaido Univ, Div Ocean & Atmospher Sci, Sapporo, Hokkaido 060, Japan. RP Ramaswamy, V (reprint author), Princeton Univ, NOAA, Geophys Fluid Dynam Lab, POB 308, Princeton, NJ 08452 USA. RI Shine, Keith/D-9093-2012; Rood, Richard/C-5611-2008; Randel, William/K-3267-2016 OI Shine, Keith/0000-0003-2672-9978; Rood, Richard/0000-0002-2310-4262; Randel, William/0000-0002-5999-7162 NR 202 TC 254 Z9 277 U1 8 U2 52 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 8755-1209 J9 REV GEOPHYS JI Rev. Geophys. PD FEB PY 2001 VL 39 IS 1 BP 71 EP 122 DI 10.1029/1999RG000065 PG 52 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 403EL UT WOS:000167029600003 ER PT J AU Wang, GL Ye, SH Qian, ZH Li, JL Ma, CP Ryan, J Gordon, D Baver, K Zhang, J Liu, X Aoki, K Ishihara, M Rich, S Clyde, C AF Wang, GL Ye, SH Qian, ZH Li, JL Ma, CP Ryan, J Gordon, D Baver, K Zhang, J Liu, X Aoki, K Ishihara, M Rich, S Clyde, C TI Measurements of the VLBI experiments during the first campaign of the Asian-Pacific space geodynamics (APSG) program SO SCIENCE IN CHINA SERIES A-MATHEMATICS PHYSICS ASTRONOMY LA English DT Article DE APSG; VLBI; crustal motion measurements AB During the first campaign of the Asian-Pacific space geodynamics (APSG) program in October 1997, two VLBI experiments were successfully organized and coordinated by the Astrometry and Geodesy VLBI Group of Shanghai Astronomical Observatory, the Chinese Academy of Sciences, cooperated with geodetic VLBI group, GSFC, NASA, USA. Six VLBI stations participated in the experiments, including Seshan and Urumqi station of China, Gilcreek station in Alaska and Kokee station in Hawaii of USA, Kashima station of Japan and Hobart station at Tasmania of Australia. Baseline lengths are from 1 900 to 11 000 km and the mean relative uncertainty of the baseline length measurements is 1.0 x 10(-9). In addition, the rates of the baseline lengths among the six stations and their three-dimensional velocities are solved out via global analysis of the two APSG sessions and the historical observations of the six stations as well as other VLBI observations from the global observation network. These results are appreciable to the studies of the modern crustal movement in the Asian-Pacific region. Especially, an 8 mm/a eastward motion and a 14 mm/a north by northeast motion are detected respectively for Seshan and Urumqi stations relative to the stable part of the Eurasian plate. The motions directly illustrate the effect of the northward movement of Indian plate on the modern crustal motions of the northwestern and the eastern part of China, which is of important significance to the study of the modern crustal motion of China. C1 Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China. Goddard Space Flight Ctr, College Pk, MD 20740 USA. Chinese Acad Sci, Urumqi Astron Observ, Urumqi 830011, Peoples R China. Geog Survey Inst, Tsukuba, Ibaraki, Japan. RP Wang, GL (reprint author), Chinese Acad Sci, Shanghai Astron Observ, Shanghai 200030, Peoples R China. RI Lin, Aoxiang/C-9978-2009; Ma, Chopo/D-4751-2012 NR 5 TC 1 Z9 2 U1 1 U2 2 PU SCIENCE PRESS PI BEIJING PA 16 DONGHUANGCHENGGEN NORTH ST, BEIJING 100717, PEOPLES R CHINA SN 1006-9283 J9 SCI CHINA SER A JI Sci. China Ser. A-Math. Phys. Astron. PD FEB PY 2001 VL 44 IS 2 BP 259 EP 264 DI 10.1007/BF02874429 PG 6 WC Mathematics, Applied; Mathematics SC Mathematics GA 406BV UT WOS:000167195800014 ER PT J AU Cesnik, CES Shin, SJ Wilbur, ML AF Cesnik, CES Shin, SJ Wilbur, ML TI Dynamic response of active twist rotor blades SO SMART MATERIALS & STRUCTURES LA English DT Article ID BEAMS; ACTUATION AB Dynamic characteristics of active twist rotor (ATR) blades are investigated analytically and experimentally in this paper. The ATR system is intended for vibration and potentially for noise reductions in helicopters through individual blade control. An aeroelastic model is developed to identify frequency response characteristics of the ATR blade with integral, generally anisotropic, strain actuators embedded in its composite construction. An ATR prototype blade was designed and manufactured to experimentally study the vibration reduction capabilities of such systems. Several bench and hover tests were conducted and those results are presented and discussed here. Selected results on sensitivity of the ATR system to collective setting (i.e. blade loading), blade rpm (i.e. centrifugal force and blade station velocity), and media density (i.e, altitude) are presented. They indicated that the twist actuation authority of the ATR blade is independent of the collective setting up to approximately 10P, and dependent on rotational speed and altitude near the torsional resonance frequency due to its dependency on the aerodynamic damping. The proposed model captures very well the physics and sensitivities to selected test parameters of the ATR system. The numerical result of the blade torsional loads show an average error of 20% in magnitude and virtually no difference in phase for the blade frequency response. Overall, the active blade model is in very good agreement with the experiments and can be used to analyze and design future active helicopter blade systems. C1 MIT, Dept Aeronaut & Astronaut, Cambridge, MA 02139 USA. NASA, Langley Res Ctr, USA, Res Labs,Vehicle Technol Directorate, Hampton, VA USA. NR 40 TC 32 Z9 33 U1 0 U2 9 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0964-1726 J9 SMART MATER STRUCT JI Smart Mater. Struct. PD FEB PY 2001 VL 10 IS 1 BP 62 EP 76 DI 10.1088/0964-1726/10/1/306 PG 15 WC Instruments & Instrumentation; Materials Science, Multidisciplinary SC Instruments & Instrumentation; Materials Science GA 408YV UT WOS:000167355500007 ER PT J AU Mendell, WW AF Mendell, WW TI A gateway for human exploration of space? The weak stability boundary SO SPACE POLICY LA English DT Editorial Material AB NASA's plans for future human exploration of the Solar System describe only missions to Mars. Before such mission can be initiated, much study remains to be done in technology development, mission operations and human performance. While, for example, technology validation and operational experience could be gained in the context of lunar exploration missions, a NASA lunar program is seen as a competitor to a Mars mission rather than a step towards it. The recently characterized weak stability boundary in the Earth-Moon gravitational field may provide an operational approach to all types of planetary exploration. and infrastructure developed for a gateway to the Solar System may be a programmatic solution for exploration that avoids the fractious bickering between Mars and Moon advocates. This viewpoint proposes utilizing the concept of Greater Earth to educate policy makers, opinion makers and the public about these subtle attributes of our space neighborhood. (C) 2001 Published by Elsevier Science Ltd. C1 NASA, Lyndon B Johnson Space Ctr, Houston, TX 77058 USA. RP Mendell, WW (reprint author), NASA, Lyndon B Johnson Space Ctr, 2101 NASA Rd 1, Houston, TX 77058 USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 0265-9646 J9 SPACE POLICY JI Space Policy PD FEB PY 2001 VL 17 IS 1 BP 13 EP 17 DI 10.1016/S0265-9646(00)00058-8 PG 5 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA 407QJ UT WOS:000167282000004 ER PT J AU Hay, SI Rogers, DJ Shanks, GD Myers, MF Snow, RW AF Hay, SI Rogers, DJ Shanks, GD Myers, MF Snow, RW TI Malaria early warning in Kenya SO TRENDS IN PARASITOLOGY LA English DT Review ID SUB-SAHARAN AFRICA; PLASMODIUM-FALCIPARUM; BORNE DISEASE; HIGHLANDS; EPIDEMIC; SYSTEMS; TRANSMISSION; CLIMATE; VECTORS; IMPACT AB Kenya displays large spatiotemporal diversity in its climate and ecology. It follows that malaria transmission will reflect this environmental heterogeneity in both space and time. In this article, we discuss how such heterogeneity, and its epidemiological consequences, should be considered in the development of early warning systems for malaria epidemics. C1 Univ Oxford, Dept Zool, TALA Res Grp, Oxford OX1 3PS, England. Armed Forces Res Inst Med Sci, USAMC, Bangkok 10400, Thailand. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Kenya Med Res Inst, Wellcome Trust Collaborat Programme, Nairobi, Kenya. Univ Oxford, John Radcliffe Hosp, Nuffield Dept Clin Med, Ctr Trop Med, Oxford OX3 9DS, England. RP Hay, SI (reprint author), Univ Oxford, Dept Zool, TALA Res Grp, S Parks Rd, Oxford OX1 3PS, England. RI Hay, Simon/F-8967-2015 OI Hay, Simon/0000-0002-0611-7272 FU Wellcome Trust [056642] NR 35 TC 43 Z9 44 U1 1 U2 7 PU ELSEVIER SCI LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND SN 1471-4922 J9 TRENDS PARASITOL JI Trends Parasitol. PD FEB PY 2001 VL 17 IS 2 BP 95 EP 99 DI 10.1016/S1471-4922(00)01763-3 PG 5 WC Parasitology SC Parasitology GA 453TV UT WOS:000169933300011 PM 11228016 ER PT J AU Smith, S Wenderoth, P van der Zwan, R AF Smith, S Wenderoth, P van der Zwan, R TI Orientation processing mechanisms revealed by the plaid tilt illusion SO VISION RESEARCH LA English DT Article DE plaid tilt illusion; orientation coding; first-order; second-order ID NON-FOURIER MOTION; 2ND-ORDER MOTION; VISUAL-SYSTEM; HUMAN VISION; CONTOURS; STIMULI; DISCRIMINATION; SELECTIVITY; INHIBITION; PERCEPTION AB The tilt after-effect (TAE) and tilt illusion (TI) have revealed a great deal about the nature of orientation coding of 1-dimensional (1D) lines and gratings. Comparatively little research however has addressed the mechanisms responsible for encoding the orientation of 2-dimensional (2D) plaid stimuli. A multi-stage model of edge detection has recently been proposed [Georgeson, M. A. (1998) Image & Vision Computing, 16(6-7). 389-405] to account for the perceived structure of a plaid stimulus that incorporates extraction of the zero-crossings (ZCs) of the plaid. Data is presented showing that the ZCs of a plaid inducing stimulus can interact with vertical grating test stimulus to induce a standard tilt illusion. However, by considering the second-order structure of a plaid rather than ZCs, it was shown that the perceived orientation of the vertical test grating results from the combination of orientation illusions due to the first- and second-order components of an inducing plaid. The data suggest that the mechanisms encoding the orientation of second-order contours are similar to, and interact directly with, those that encode first-order contours. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 NASA, Ames Res Ctr, Flight Management & Human Factors Div, Moffett Field, CA 94035 USA. Macquarie Univ, Dept Psychol, Sydney, NSW 2109, Australia. Univ Sydney, Dept Psychol, Sydney, NSW 2006, Australia. RP Smith, S (reprint author), NASA, Ames Res Ctr, Flight Management & Human Factors Div, MS 262-2, Moffett Field, CA 94035 USA. RI Smith, Stuart/A-9037-2013; Smith, Stuart/B-8144-2011 OI Smith, Stuart/0000-0002-4735-6026; Smith, Stuart/0000-0002-4735-6026 NR 51 TC 3 Z9 3 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0042-6989 J9 VISION RES JI Vision Res. PD FEB PY 2001 VL 41 IS 4 BP 483 EP 494 DI 10.1016/S0042-6989(00)00268-6 PG 12 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA 400WP UT WOS:000166894900007 PM 11166051 ER PT J AU Reale, O Atlas, R AF Reale, O Atlas, R TI Tropical cyclone-like vortices in the extratropics: Observational evidence and synoptic analysis SO WEATHER AND FORECASTING LA English DT Article ID SEA INTERACTION THEORY; DEEP CYCLOGENESIS; LEE CYCLOGENESIS; ALPS; STORM; MODEL AB In this article two subsynoptic-scale cyclones that developed between 3 and 10 October 1996 over the western-central Mediterranean, causing floods. strong winds, and severe damage, are analyzed. Surface observations reveal that the accumulated rainfall at Santuario di Polsi (southern Calabria, Italy) is more than 480 mm for the first event (cyclone 9610A). The second cyclone (9610B) was characterized by a storm track predominantly over the sea, thus causing less recorded precipitation, but stronger wind. Satellite imagery shows two intensely convective vortices with a scale of 200-400 km and a spiral structure, with the cyclone 9610B displaying a well-defined eyelike feature. The corresponding National Centers for Environmental Prediction analyses. although limited by 1 degrees resolution, confirm the cyclones' positions and intensities. as they can be inferred from satellite imagery, SSM/I data, and observations, but display also the "signature" of two tropical cyclone-like vortices, including a perfect alignment between the cutoffs at all levels with the surface center, and a warm core. The wind speed cross sections in the meridional and zonal directions through the eyelike feature reveal a virtually motionless column of air. A comparison with the cross sections taken in the same analyses across a named tropical storm in the Atlantic show a strong analogy between the gridded representation of these events. Other remarkable features include very strong horizontal shear in the midtroposphere. and simultaneous lack of vertical shear; increasing low-level vorticity at the expenses of upper-level vorticity; creation of a low-level vorticity maximum; and finally strong low-level convergence and upper-level divergence during the onset and development of each cyclone. C1 Ctr Ocean Land Atmosphere Studies, Calverton, MD 20705 USA. NASA, Goddard Space Flight Ctr, Atmospheres Lab, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Ctr Ocean Land Atmosphere Studies, 4041 Powder Mill Rd,Suite 302, Calverton, MD 20705 USA. EM reale@cola.iges.org RI Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 44 TC 54 Z9 54 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0882-8156 EI 1520-0434 J9 WEATHER FORECAST JI Weather Forecast. PD FEB PY 2001 VL 16 IS 1 BP 7 EP 34 DI 10.1175/1520-0434(2001)016<0007:TCLVIT>2.0.CO;2 PG 28 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 410HX UT WOS:000167435500003 ER PT J AU Dworkin, JP Deamer, DW Sandford, SA Allamandola, LJ AF Dworkin, JP Deamer, DW Sandford, SA Allamandola, LJ TI Self-assembling amphiphilic molecules: Synthesis in simulated interstellar/precometary ices SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article DE vesicle; amphiphile; origin of life; interstellar ice; cometary delivery ID METHANOL; MACROMOLECULES; ENCAPSULATION; EVOLUTION; ANALOGS AB Interstellar gas and dust constitute the primary material from which the solar system formed. Near the end of the hot early phase of star and planet formation, volatile, less refractory materials were transported into the inner solar system as comets and interplanetary dust particles. Once the inner planets had sufficiently cooled, late accretionary infall seeded them with complex organic compounds [Oro, J. (1961) Nature (London) 190, 389-390; Delsemme, A. H. (1984) Origins Life 14, 51-60; Anders, E. (1989) Nature (London) 342, 255-257; Chyba, C. F. & Sagan, C. (1992) Nature (London) 355, 125-131]. Delivery of such extraterrestrial compounds may have contributed to the organic inventory necessary for the origin of life. Interstellar ices, the building blocks of comets, tie up a large fraction of the biogenic elements available in molecular clouds. In our efforts to understand their synthesis, chemical composition, and physical properties, we report here that a complex mixture of molecules is produced by UV photolysis of realistic, interstellar ice analogs, and that some of the components have properties relevant to the origin of life, including the ability to self-assemble into vesicular structures. C1 NASA, Ames Res Ctr, Astrochem Lab, Moffett Field, CA 94035 USA. Search Extraterr Intelligence Inst, Mountain View, CA 94043 USA. Univ Calif Santa Cruz, Dept Chem & Biochem, Santa Cruz, CA 95064 USA. RP Sandford, SA (reprint author), NASA, Ames Res Ctr, Astrochem Lab, Mail Stop 245-6, Moffett Field, CA 94035 USA. EM ssandford@mail.arc.nasa.gov RI Dworkin, Jason/C-9417-2012 OI Dworkin, Jason/0000-0002-3961-8997 NR 17 TC 120 Z9 122 U1 4 U2 32 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 JAN 30 PY 2001 VL 98 IS 3 BP 815 EP 819 DI 10.1073/pnas.98.3.815 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 399JF UT WOS:000166807300012 PM 11158552 ER PT J AU Chen, CL Shen, J Chen, SY Luo, GP Chu, CW Miranda, FA Van Keuls, FW Jiang, JC Meletis, EI Chang, HY AF Chen, CL Shen, J Chen, SY Luo, GP Chu, CW Miranda, FA Van Keuls, FW Jiang, JC Meletis, EI Chang, HY TI Epitaxial growth of dielectric Ba0.6Sr0.4TiO3 thin film on MgO for room temperature microwave phase shifters SO APPLIED PHYSICS LETTERS LA English DT Article ID TITANATE AB Dielectric Ba0.6Sr0.4TiO3 thin films were epitaxially grown on (001) MgO by using pulsed laser ablation. Microstructure studies from x-ray diffraction and electron microscopy suggest that the as-grown films are c-axis oriented with an interface relationship of < 100 > BSTO//< 100 > MgO. A room temperature coupled microwave phase shifter has been developed with a phase shift near 250 degrees at 23.675 GHz under an electrical field of 40 V/mum and a figure of merit of similar to 53 degrees /dB. The performance of the microwave phase shifter based on the epitaxial Ba0.6Sr0.4TiO3 thin films on (001) MgO is close to that needed for practical applications in wireless communications. (C) 2001 American Institute of Physics. C1 Univ Houston, Texas Ctr Superconduct, Houston, TX 77204 USA. Glenn Res Ctr, Commun Technol Div, Cleveland, OH 44135 USA. Louisiana State Univ, Dept Mech Engn, Baton Rouge, LA 70803 USA. Univ Calif Berkeley, Lawrence Berkeley Lab, Berkeley, CA 94720 USA. RP Chen, CL (reprint author), Univ Houston, Texas Ctr Superconduct, Houston, TX 77204 USA. NR 17 TC 138 Z9 153 U1 1 U2 13 PU AMER INST PHYSICS PI MELVILLE PA 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JAN 29 PY 2001 VL 78 IS 5 BP 652 EP 654 DI 10.1063/1.1343499 PG 3 WC Physics, Applied SC Physics GA 398CC UT WOS:000166737500031 ER PT J AU Santos, J Mintz, EA Zehnder, O Bosshard, C Bu, XR Gunter, P AF Santos, J Mintz, EA Zehnder, O Bosshard, C Bu, XR Gunter, P TI New class of imidazoles incorporated with thiophenevinyl conjugation pathway for robust nonlinear optical chromophores SO TETRAHEDRON LETTERS LA English DT Article ID DERIVATIVES; POLYMERS AB A new series of thermally stable heterocyclic imidazole-based nonlinear optical chromophores has been developed. These chromophores possess a thiophene based stilbene conjugation pathway with a nitro acceptor group attached to the phenyl end. This feature leads to robust chromophores with high thermal stability and enhanced molecular nonlinearity. (C) 2001 Elsevier Science Ltd. All rights reserved. C1 Clark Atlanta Univ, Dept Chem, Atlanta, GA 30314 USA. Clark Atlanta Univ, NASA, Ctr High Performance Polymers & Composites, Atlanta, GA 30314 USA. ETH Zurich, Swiss Fed Inst Technol, Nonlinear Opt Lab, Inst Quantum Elect, CH-8093 Zurich, Switzerland. RP Bu, XR (reprint author), Clark Atlanta Univ, Dept Chem, Atlanta, GA 30314 USA. RI gunter, peter/H-3171-2011 NR 8 TC 69 Z9 71 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0040-4039 J9 TETRAHEDRON LETT JI Tetrahedron Lett. PD JAN 29 PY 2001 VL 42 IS 5 BP 805 EP 808 DI 10.1016/S0040-4039(00)02143-2 PG 4 WC Chemistry, Organic SC Chemistry GA 398AA UT WOS:000166730500010 ER PT J AU Remsberg, EE Bhatt, PP Deaver, LE AF Remsberg, EE Bhatt, PP Deaver, LE TI Ozone changes in the lower stratosphere from the Halogen Occultation Experiment for 1991 through 1999 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SAGE II; SEASONAL-VARIATIONS; WATER-VAPOR; TRENDS; VARIABILITY; PROFILES; CIRCULATION; TROPOPAUSE; ATMOSPHERE; PINATUBO AB The Upper Atmospheric Research Satellite (UARS) Halogen Occultation Experiment (HALOE) Version 19 ozone profile data set was analyzed for both periodic and nonseasonal polynomial changes in lower stratospheric ozone fur 1991-1999. The profile data were screened for cloud contamination at the lowest levels and were then integrated within six half-Umkehr teach similar to2.5 km thick) layers from 32 to 253 hPa. The column values were then binned and averaged into 10 degrees -wide latitude regions but separated into sunrise and sunset measurements, yielding an effective time series of zonal-averaged ozone that spans 8 years. The results extend to near tropopause levels, 253 hPa in the extratropics and 127 hPa in the tropics. Multiple linear regression techniques were applied to the data of each latitude zone and half-Umkehr layer. We developed models that included annual, semiannual, and interannual periodic terms plus polynomial terms at 50 degreesN, 30 degreesN, equator, 30 degreesS, and 50 degreesS. The amplitudes of the three periodic terms vary with latitude and pressure altitude and do not maintain their same order of importance in all cases, emphasizing the changes and hemispheric asymmetry of the transport mechanisms in the lower stratosphere. We find no clear evidence for long-term change at most latitudes and layers. Steady declines in ozone of 0.5% yr(-1) were found in the 32-45 hPa layer at 50 degreesS, most likely due to transport of ozone-depleted air from higher latitudes. Our lowest tropical layer (90-127 hPa) shows an ozone decline in the early 1990s but an increase in the last half of the decade. Steady increases of ozone of 3-4% yr(-1) were found at 50 degreesN from 127 to 253 hPa and at 30 degreesN from 179 to 253 hPa, probably in response to a changing net circulation for the Northern Hemisphere lower stratosphere. However, there is no highly significant trend at 50 degreesN for the column Ozone over the deeper layer from 8 to 253 hPa. For Northern Hemisphere middle latitudes it is concluded that the previously reported declines of zonal-average ozone in the lower stratosphere for the 1980s and early 1990s have not continued over the decade of the 1990s. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. Sci Applicat Int Corp, Hampton, VA 23666 USA. RP Remsberg, EE (reprint author), NASA, Langley Res Ctr, MS 401B,21 Langley Blvd, Hampton, VA 23681 USA. EM e.e.remsberg@larc.nasa.gov; p.p.bhatt@larc.nasa.gov; l.e.deaver@larc.nasa.gov NR 36 TC 14 Z9 14 U1 0 U2 2 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 JAN 27 PY 2001 VL 106 IS D2 BP 1639 EP 1653 DI 10.1029/2000JD900596 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 395TB UT WOS:000166596400014 ER PT J AU Huang, FT Reber, CA AF Huang, FT Reber, CA TI "Synoptic" estimates of chemically active species and other diurnally varying parameters in the stratosphere, derived from measurements from the Upper Atmosphere Research Satellite (UARS) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RESOLUTION DOPPLER IMAGER; MICROWAVE LIMB SOUNDER; MIDDLE ATMOSPHERE; MODEL; WINDS; TIDES AB Over the past two decades there have been numerous articles in the literature discussing methods of obtaining global-scale "synoptic" mathematical representations from asynoptic satellite observations. These studies cover a wide range of viewpoints, ranging from claims of presenting synoptic maps to opinions stating that synoptic representations cannot be obtained from asynoptic data alone, and that physical models are needed to augment the measurements. We review and comment on many of these previous studies. We do not believe that previous published representations generated from Upper Atmosphere Research Satellite data alone for variables that exhibit significant diurnal variations, are indeed synoptic. However, we show that UARS data can be used to estimate useful synoptic approximations without the need for physical models. Using a two-dimensional Fourier least squares algorithm, we calculate mathematical approximations to "synoptic maps." We provide examples for ClO, ClONO2, NO2, O-3, CH4, temperature, and winds and discuss how they can provide new information on both the chemistry and dynamics of the atmosphere. C1 Sci Syst & Appl Inc, Lanham, MD 20706 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Huang, FT (reprint author), Sci Syst & Appl Inc, 5900 Princess Garden Pkwy,Suite 300, Lanham, MD 20706 USA. NR 33 TC 7 Z9 7 U1 0 U2 0 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 JAN 27 PY 2001 VL 106 IS D2 BP 1655 EP 1667 DI 10.1029/2000JD900515 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 395TB UT WOS:000166596400015 ER PT J AU Rotman, DA Tannahill, JR Kinnison, DE Connell, PS Bergmann, D Proctor, D Rodriguez, JM Lin, SJ Rood, RB Prather, MJ Rasch, PJ Considine, DB Ramaroson, R Kawa, SR AF Rotman, DA Tannahill, JR Kinnison, DE Connell, PS Bergmann, D Proctor, D Rodriguez, JM Lin, SJ Rood, RB Prather, MJ Rasch, PJ Considine, DB Ramaroson, R Kawa, SR TI Global Modeling Initiative assessment model: Model description, integration, and testing of the transport shell SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; 3-DIMENSIONAL MODEL; MIDDLE ATMOSPHERE; TRACER TRANSPORT; STRATOSPHERE; AIRCRAFT; TROPOSPHERE; SIMULATION; CHEMISTRY; OZONE AB We describe the three-dimensional global stratospheric chemistry model developed under the NASA Global Modeling Initiative (GMI) to assess the possible environmental consequences from the emissions of a fleet of proposed high-speed civil transport aircraft. This model was developed through a unique collaboration of the members of the CMI team. Team members provided computational modules representing various physical and chemical processes, and analysis of simulation results through extensive comparison to observation. The team members' modules were integrated within a computational framework that allowed transportability and simulations on massively parallel computers. A unique aspect of this model framework is the ability to interchange and intercompare different submodules to assess the sensitivity of numerical algorithms and model assumptions to simulation results. In this paper, we discuss the important attributes of the GMI effort and describe the CMI model computational framework and the numerical modules representing physical and chemical processes. As an application of the concept, we illustrate an analysis of the impact of advection algorithms on the dispersion of a NOy-like source in the stratosphere which mimics that of a fleet of commercial supersonic transports thigh-speed civil transport (HSCT)) flying between 17 and 20 km. C1 Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Univ Calif Irvine, Dept Earth Syst Sci, Irvine, CA 92697 USA. Off Natl Etud & Rech Aerosp, F-92322 Chatillon, France. Univ Miami, Dept Marine & Atmospher Chem, Miami, FL 33149 USA. RP Rotman, DA (reprint author), Univ Calif Lawrence Livermore Natl Lab, Mail Stop Li-103, Livermore, CA 94550 USA. RI Bergmann, Daniel/F-9801-2011; Kawa, Stephan/E-9040-2012; Rodriguez, Jose/G-3751-2013; Rood, Richard/C-5611-2008 OI Bergmann, Daniel/0000-0003-4357-6301; Rodriguez, Jose/0000-0002-1902-4649; Rood, Richard/0000-0002-2310-4262 NR 61 TC 44 Z9 44 U1 2 U2 9 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 JAN 27 PY 2001 VL 106 IS D2 BP 1669 EP 1691 DI 10.1029/2000JD900463 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 395TB UT WOS:000166596400016 ER PT J AU Kinnison, DE Connell, PS Rodriguez, JM Rotman, DA Considine, DB Tannahill, J Ramaroson, R Rasch, PJ Douglass, AR Baughcum, SL Coy, L Waugh, DW Kawa, SR Prather, MJ AF Kinnison, DE Connell, PS Rodriguez, JM Rotman, DA Considine, DB Tannahill, J Ramaroson, R Rasch, PJ Douglass, AR Baughcum, SL Coy, L Waugh, DW Kawa, SR Prather, MJ TI The Global Modeling Initiative assessment model: Application to high-speed civil transport perturbation SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; MIDDLE ATMOSPHERE; LOWER STRATOSPHERE; AIRCRAFT; NITROGEN; CHEMISTRY; CONTRAST; RADICALS; DIOXIDE; OXIDE AB The NASA Atmospheric Effects of Aviation Project (AEAP) Global Modeling Initiative (GMI) three-dimensional (3-D) chemical transport model (CTM) was applied to assess the impact of a fleet of high-speed civil transports (HSCTs) on abundances of stratospheric ozone, total inorganic nitrogen (NOy), and H2O. This model is specifically designed to incorporate a diversity of approaches to chemical and physical processes related to the stratosphere in a single computing framework, facilitating the analysis of model component differences, modeling intercomparison and comparison with data. A proposed HSCT fleet scenario was adopted, in which the aircraft cruise in the lower stratosphere, emitting nitrogen oxides (NOx) and water (H2O). The model calculated an HSCT-induced change in Northern and Southern Hemisphere total column ozone of +0.2% and +0.05%, respectively. This change is the result of a balance between an increase in local ozone below approximately 25 km and a decrease above this altitude. When compared to available NOy observations, we find that the model consistently underestimates lower stratospheric NOy. This discrepancy is consistent with the model bias toward less negative ozone impact, when compared to results from other models. Additional analysis also indicates that for an HSCT assessment it is equally important for a model to accurately represent the lower stratospheric concentrations of ozone and H2O. The GMI model yields good agreement In comparisons to ozone data For present-day conditions, while H2O is constrained by climatology as much as possible; thus no further biases would be expected from these comparisons. Uncertainties due to discrepancies in the calculated age of ail compared to that derived from measurements, and of the impact of emissions on heterogeneous and polar chemistry, are difficult to evaluate at this point. C1 Natl Ctr Atmospher Res, Boulder, CO 80307 USA. Boeing Co, Seattle, WA 98124 USA. Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Irvine, Dept Earth Syst Sci, Irvine, CA 92697 USA. Off Natl Etud & Rech Aerosp, F-92322 Chatillon, France. Univ Miami, Dept Marine & Atmospher Chem, Miami, FL 33149 USA. Johns Hopkins Univ, Dept Earth & Planetary Sci, Baltimore, MD USA. Univ Maryland, Dept Meteorol, College Pk, MD 20742 USA. RP Kinnison, DE (reprint author), Natl Ctr Atmospher Res, POB 3000, Boulder, CO 80307 USA. RI Douglass, Anne/D-4655-2012; Kawa, Stephan/E-9040-2012; Rodriguez, Jose/G-3751-2013; Waugh, Darryn/K-3688-2016 OI Rodriguez, Jose/0000-0002-1902-4649; Waugh, Darryn/0000-0001-7692-2798 NR 60 TC 17 Z9 17 U1 0 U2 2 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 JAN 27 PY 2001 VL 106 IS D2 BP 1693 EP 1711 DI 10.1029/2000JD900406 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 395TB UT WOS:000166596400017 ER PT J AU Voss, PB Stimpfle, RM Cohen, RC Hanisco, TF Bonne, GP Perkins, KK Lanzendorf, EJ Anderson, JG Salawitch, RJ Webster, CR Scott, DC May, RD Wennberg, PO Newman, PA Lait, LR Elkins, JW Bui, TP AF Voss, PB Stimpfle, RM Cohen, RC Hanisco, TF Bonne, GP Perkins, KK Lanzendorf, EJ Anderson, JG Salawitch, RJ Webster, CR Scott, DC May, RD Wennberg, PO Newman, PA Lait, LR Elkins, JW Bui, TP TI Inorganic chlorine partitioning in the summer lower stratosphere: Modeled and measured [ClONO2]/[HCl] during POLARIS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID IN-SITU MEASUREMENTS; NASA ER-2 AIRCRAFT; RATE COEFFICIENTS; UPPER TROPOSPHERE; HCL; NITROGEN; RADICALS; CLO; NO2; O-3 AB We examine inorganic chlorine (Cl-y) partitioning in the summer lower stratosphere using in situ ER-2 aircraft observations made during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) campaign. New steady state and numerical models estimate [ClONO2]/[HCl] using currently accepted photochemistry. These models are tightly constrained by observations with OH (parameterized as a function of solar zenith angle) substituting for modeled HO2 chemistry. We find that inorganic chlorine photochemistry alone overestimates observed [ClONO2]/[HCl] by approximately 55-60% at mid and high latitudes. On the basis of POLARIS studies of the inorganic chlorine budget, [ClO]/[ClONO2], and an intercomparison with balloon observations, the most direct explanation for the model-measurement discrepancy in Cl-y partitioning is an error in the reactions, rate constants, and measured species concentrations linking HCl and ClO (simulated [ClO]/[HCl] too high) in combination with a possible systematic error in the ER-2 ClONO2 measurement (too low). The high precision of our simulation (+/-15% 1 sigma for [ClONO2]/[HCl], which is compared with observations) increases confidence in the observations, photolysis calculations, and laboratory rate constants. These results, along with other findings, should lead to improvements in both the accuracy and precision of stratospheric photochemical models. C1 Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02144 USA. CALTECH, Div Geol & Planetary Sci, Pasadena, CA 91125 USA. CALTECH, Jet Prop Lab, Pasadena, CA 91125 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NOAA, Climate Monitoring & Diagnost Lab, Boulder, CO 80303 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Voss, PB (reprint author), Harvard Univ, Dept Chem & Biol Chem, Cambridge, MA 02144 USA. RI Salawitch, Ross/B-4605-2009; Cohen, Ronald/A-8842-2011; Wennberg, Paul/A-5460-2012; Newman, Paul/D-6208-2012; Bonne, Gisele/G-3121-2013 OI Salawitch, Ross/0000-0001-8597-5832; Cohen, Ronald/0000-0001-6617-7691; Newman, Paul/0000-0003-1139-2508; NR 51 TC 6 Z9 6 U1 2 U2 4 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 JAN 27 PY 2001 VL 106 IS D2 BP 1713 EP 1732 DI 10.1029/2000JD900494 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 395TB UT WOS:000166596400018 ER PT J AU Burch, JL Mende, SB Mitchell, DG Moore, TE Pollock, CJ Reinisch, BW Sandel, BR Fuselier, SA Gallagher, DL Green, JL Perez, JD Reiff, PH AF Burch, JL Mende, SB Mitchell, DG Moore, TE Pollock, CJ Reinisch, BW Sandel, BR Fuselier, SA Gallagher, DL Green, JL Perez, JD Reiff, PH TI Views of Earth's magnetosphere with the IMAGE satellite SO SCIENCE LA English DT Article ID RING CURRENT; MODEL AB The IMAGE spacecraft uses photon and neutral atom imaging and radio sounding techniques to provide global images of Earth's inner magnetosphere and upper atmosphere. Auroral imaging at ultraviolet wavelengths shows that the proton aurora is displaced equatorward with respect to the electron aurora and that discrete auroral forms at higher Latitudes are caused almost completely by electrons. Energetic neutral atom imaging of ions injected into the inner magnetosphere during magnetospheric disturbances shows a strong energy-dependent drift that Leads to the formation of the ring current by ions in the several tens of kiloelectron volts energy range. Ultraviolet imaging of the plasmasphere has revealed two unexpected features-a premidnight trough region and a dayside shoulder region-and has confirmed the 30-year-old theory of the formation of a plasma tail extending from the duskside plasmasphere toward the magnetopause. C1 SW Res Inst, San Antonio, TX 78228 USA. Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Massachusetts, Ctr Atmospher Res, Lowell, MA 01854 USA. Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA. Lockheed Martin Adv Technol Ctr, Palo Alto, CA 94304 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Auburn Univ, Dept Phys, Auburn, AL 36849 USA. Rice Univ, Dept Phys & Astron, Houston, TX 77005 USA. RP Burch, JL (reprint author), SW Res Inst, PO Drawer 28510, San Antonio, TX 78228 USA. RI Moore, Thomas/D-4675-2012; Reiff, Patricia/D-2564-2014 OI Moore, Thomas/0000-0002-3150-1137; Reiff, Patricia/0000-0002-8043-5682 NR 32 TC 106 Z9 107 U1 1 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD JAN 26 PY 2001 VL 291 IS 5504 BP 619 EP 624 DI 10.1126/science.291.5504.619 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 396BG UT WOS:000166616000034 PM 11158668 ER PT J AU Sleep, NH Zahnle, K AF Sleep, NH Zahnle, K TI Carbon dioxide cycling and implications for climate on ancient Earth SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Review ID ATMOSPHERIC CO2; OCEANIC-CRUST; HYDROTHERMAL CIRCULATION; SURFACE TEMPERATURES; DEGASSING HISTORY; PHANEROZOIC TIME; THERMAL HISTORY; MOUNT-ETNA; LAYER 2A; EVOLUTION AB The crustal Urey cycle of CO2 involving silicate weathering and metamorphism acts as a dynamic climate buffer. In this cycle, warmer temperatures speed silicate weathering and carbonate formation, reducing atmospheric CO2 and thereby inducing global cooling. Over long periods of time, cycling of CO2 into and out of the mantle also dynamically buffers CO2. In the mantle cycle, CO2 is outgassed at ridge axes and island arcs, while subduction of carbonatized oceanic basalt and pelagic sediments returns CO2 to the mantle. Negative feedback is provided because the amount of basalt carbonatization depends on CO2 in seawater and therefore on CO2 in the air. On the early Earth, processes involving tectonics were more vigorous than at present, and the dynamic mantle buffer dominated over the crustal one. The mantle cycle would have maintained atmospheric and oceanic CO2 reservoirs at levels where the climate was cold in the Archean unless another greenhouse gas was important. Reaction of CO2 with impact ejecta and its eventual subduction produce even lower levels of atmospheric CO2 and small crustal carbonate reservoirs in the Hadean. Despite its name, the Hadean climate would have been freezing unless tempered by other greenhouse gases. C1 Stanford Univ, Dept Geophys, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Sleep, NH (reprint author), Stanford Univ, Dept Geophys, Mitchell Bldg,Room 360,397 Panama Mall, Stanford, CA 94305 USA. NR 101 TC 198 Z9 205 U1 8 U2 72 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 JAN 25 PY 2001 VL 106 IS E1 BP 1373 EP 1399 DI 10.1029/2000JE001247 PG 27 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 395TJ UT WOS:000166597100001 ER PT J AU Duxbury, NS Zotikov, IA Nealson, KH Romanovsky, VE Carsey, FD AF Duxbury, NS Zotikov, IA Nealson, KH Romanovsky, VE Carsey, FD TI A numerical model for an alternative origin of Lake Vostok and its exobiological implications for Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID EAST ANTARCTICA; ICE; WATER; TRITON; HEAT AB In connection with recent Galileo images of the Jovian satellite Europa, there has been a significantly increased interest in the subglacial Lake Vostok in central East Antarctica. Since the theoretical prediction by Zotikov [1961] of the existence of lakes (one of which later was named Vostok) under similar to4 km of ice in Antarctica and its confirmation by radar measurements from aircraft in 1974 [Robin et al., 1977] and from the ERS-1 satellite in 1993, it was tacitly assumed that the lake originated from the basal melting of ice [e.g., Zotikov, 1961, 1977, 1986; Kapitsa et al., 1996]. Recently, Zotikov and Duxbury [2000] proposed an alternative hypothesis that Lake Vostok had existed on the surface before the Antarctic perennial glaciation began 5-30 Myr ago, then it was buried under the thermally protecting ice and never froze all the way to the bottom. In this study we support our hypothesis by comprehensive numerical modeling and evaluate its interesting implications for Mars and exobiology. Our numerical experiments on the sensitivity of the freezing depth to different upper boundary temperatures and different internal heat flows and the recent Mars Global Surveyor Mars Orbiter Laser Altimeter (MOLA) data support our model of the origin of possible subpolar water on Mars versus the old basal melting hypothesis. We also propose here experimental tests for our hypothesis. As a result of our computations, we conclude that Lake Vostok has survived the Antarctic glaciation without freezing completely, if it were initially an open lake with a surprisingly small water depth (greater than similar to 53 m). The current water depth at a single point is as much as 500 m [Verkulich et al., 1996]. This maximum freezing depth of similar to 53 m was reached in only 3300 years when the total upper ice cover was only similar to 600 m. The computed critical water depth is applicable to other Antarctic lakes under a thick ice cover. For the Martian internal heat flow we have computed the critical water depth to be similar to 63 m. The existence of the lake before the accumulation of ice in Antarctica implies that possible microorganisms and their remnants in the lake can be older than the Antarctic ice sheet, i.e., older than 5-30 Myr. If future observations find water under the Martian polar caps, this subpolar water, according to our model, has originated from lakes that were on the Martian surface before the formation of Mars' polar caps and have not completely frozen. Such environments would be ideal candidates for extant or extinct life on the red planet. This argues for a drilling mission at the Martian polar caps. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Russian Acad Sci, Inst Geog, Moscow 109017, Russia. Univ Alaska, Inst Geophys, Fairbanks, AK 99701 USA. RP Duxbury, NS (reprint author), CALTECH, Jet Prop Lab, Mail Stop 183-501,4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 38 TC 23 Z9 23 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2001 VL 106 IS E1 BP 1453 EP 1462 DI 10.1029/2000JE001254 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 395TJ UT WOS:000166597100005 ER PT J AU Hinson, DP Tyler, GL Hollingsworth, JL Wilson, RJ AF Hinson, DP Tyler, GL Hollingsworth, JL Wilson, RJ TI Radio occultation measurements of forced atmospheric waves on Mars SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GENERAL-CIRCULATION MODEL; MARTIAN ATMOSPHERE; THERMAL TIDES; GLOBAL SURVEYOR; DUST STORMS; SIMULATIONS; SURFACE; VARIABILITY; TOPOGRAPHY; DYNAMICS AB Mars Global Surveyor performed a series of radio occultation experiments in December 1998, resulting in 36 profiles of the neutral atmosphere in late northern spring (L-s = 74.1 degrees -77.3 degrees), The measurements are confined in latitude (64.6 degrees -67.2 degreesN) and local time (0321-0418), but their distribution in longitude is fairly uniform. We used least squares spectral analysis to characterize the zonal structure of the atmosphere and constructed longitude-height cross sections of both temperature and geopotential. Zonal variations of temperature exceed 12 K near the surface but are much smaller (2-3 K) at higher altitudes. Zonal variations of geopotential are similar to 200 m throughout the vertical range of the measurements. These patterns of temperature and geopotential appear to be stationary relative to the surface with little day-to-day variation within the 7-sol span of the measurements. We relied heavily on Mars general circulation models (GCMs) for guidance in understanding these data. Stationary planetary waves are responsible for some aspects of the temperature and geopotential fields, particularly at pressures exceeding 100-200 Pa. On the basis of strong similarities between a GCM simulation and the observations, we conclude that the disturbance takes the form of a planetary wave train excited by Alba Patera. The data also include the signature of non-Sun-synchronous thermal tides, which produce a pattern that appears to be stationary when sampled at fixed local time. Comparison between a GCM simulation and the measured geopotential field provides evidence for the presence of the resonantly enhanced, diurnal, wave-1 Kelvin mode. C1 Stanford Univ, Dept Elect Engn, Stanford, CA 94305 USA. NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NOAA, Geophys Fluid Dynam Lab, Princeton, NJ USA. RP Hinson, DP (reprint author), Stanford Univ, Dept Elect Engn, 350 Serra Mall, Stanford, CA 94305 USA. NR 56 TC 47 Z9 48 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JAN 25 PY 2001 VL 106 IS E1 BP 1463 EP 1480 DI 10.1029/2000JE001291 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA 395TJ UT WOS:000166597100006 ER PT J AU Farassat, F AF Farassat, F TI Acoustic radiation from rotating blades - The Kirchhoff method in aeroacoustics SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID QUADRUPOLE NOISE; FORMULATION; PREDICTION AB This paper reviews the current status of discrete frequency noise prediction for rotating blade machinery in the time domain. There are two major approaches both of which can be classified as the Kirchhoff method. These methods depend on the solution of two linear wave equations called the K and FW-H equations. The solutions of these equations for subsonic and supersonic surfaces are discussed and some important results of the research in the past years are presented. This paper is analytical in nature and emphasizes the work of the author and co-workers at NASA Langley Research Center. (C) 2001 Academic Press. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Farassat, F (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 41 TC 12 Z9 17 U1 1 U2 8 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD JAN 25 PY 2001 VL 239 IS 4 BP 785 EP 800 DI 10.1006/jsvi.2000.3221 PG 16 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 398UB UT WOS:000166773900012 ER PT J AU Maestrello, L AF Maestrello, L TI The influence of initial forcing on non-linear control SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID NONLINEAR DYNAMICS; SUPERSONIC JETS; BOUNDARY-LAYER; CHAOS; SYSTEM; SOUND AB The property of sensitive dependence on initial forcing may be used as an effective trigger of changes in a system response and, thus, used to redistribute energy favorably and efficiently. One unstable periodic orbit was selected from each experiment to demonstrate the role of the initial forcing in an active control strategy to yield improved performance. (C) 2001 Academic Press. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Maestrello, L (reprint author), NASA, Langley Res Ctr, Hampton, VA 23681 USA. NR 30 TC 3 Z9 3 U1 0 U2 1 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD JAN 25 PY 2001 VL 239 IS 4 BP 873 EP 883 DI 10.1006/jsvi.2000.3222 PG 11 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA 398UB UT WOS:000166773900017 ER PT J AU Burl, MC Doleman, BJ Schaffer, A Lewis, NS AF Burl, MC Doleman, BJ Schaffer, A Lewis, NS TI Assessing the ability to predict human percepts of odor quality from the detector responses of a conducting polymer composite-based electronic nose SO SENSORS AND ACTUATORS B-CHEMICAL LA English DT Article DE electronic nose; conducting polymer composites; odor quality; human perception; olfaction; regression models; feature selection ID INTENSITY; OLFACTION; MIXTURES; ARRAYS AB The responses of a conducting polymer composite "electronic nose" detector array were used to predict human perceptual descriptors of odor quality for a selected test set of analytes. The single-component odorants investigated in this work included molecules that are chemically quite distinct from each other, as well as molecules that are chemically similar to each other but which are perceived as having distinct odor qualities by humans. Each analyte produced a different, characteristic response pattern on the electronic nose array, with the signal strength on each detector reflecting the relative binding of the odorant into the various conducting polymer composites of the detector array. A "human perceptual space" was defined by reference to English language descriptors that are frequently used to describe odors. Data analysis techniques, including standard regression, nearest-neighbor prediction, principal components regression, partial least squares regression, and feature subset selection, were then used to determine mappings from electronic nose measurements to this human perceptual space. The effectiveness of the derived mappings was evaluated by comparison with average human perceptual data published by Dravnieks. For specific descriptors, some models provided cross-validated predictions that correlated well with the human data (above the 0.60 level), but none of the models could accurately predict the human values for more than a few descriptors. (C) 2001 Elsevier Science B.V. All rights reserved. C1 CALTECH, Div Chem & Chem Engn, Noyes Lab 127 72, Pasadena, CA 91125 USA. Jet Prop Lab, Pasadena, CA 91109 USA. RP Lewis, NS (reprint author), CALTECH, Div Chem & Chem Engn, Noyes Lab 127 72, Pasadena, CA 91125 USA. EM nslewis@caltech.edu NR 23 TC 38 Z9 38 U1 0 U2 6 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0925-4005 J9 SENSOR ACTUAT B-CHEM JI Sens. Actuator B-Chem. PD JAN 25 PY 2001 VL 72 IS 2 BP 149 EP 159 DI 10.1016/S0925-4005(00)00645-6 PG 11 WC Chemistry, Analytical; Electrochemistry; Instruments & Instrumentation SC Chemistry; Electrochemistry; Instruments & Instrumentation GA 397HW UT WOS:000166688100008 ER PT J AU Cassell, AM Verma, S Delzeit, L Meyyappan, M Han, J AF Cassell, AM Verma, S Delzeit, L Meyyappan, M Han, J TI Combinatorial optimization of heterogeneous catalysts used in the growth of carbon nanotubes SO LANGMUIR LA English DT Letter AB Libraries of liquid-phase catalyst precursor solutions were printed onto iridium-coated silicon substrates and evaluated for their effectiveness in catalyzing the growth of multiwalled carbon nanotubes (MWNTs) by chemical vapor deposition (CVD). The catalyst precursor solutions were composed of inorganic salts and a removable triblock copolymer (EO)(20)(PO)(70)(EO)(20) (EO = ethylene oxide, PO = propylene oxide) structure-directing agent (SDA), dissolved in ethanol/methanol mixtures. Sample libraries were quickly assayed using scanning electron microscopy after CVD growth to identify active catalysts and CVD conditions. Composition libraries and focus libraries were then constructed around the active spots identified in the discovery libraries to understand how catalyst precursor composition affects the yield, density, and quality of the nanotubes. Successful implementation of combinatorial optimization methods in the development of highly active, carbon nanotube catalysts is demonstrated, as well as the identification of catalyst formulations that lead to varying densities and shapes of aligned nanotube towers. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Cassell, AM (reprint author), Eloret Corp, Sunnyvale, CA 94087 USA. NR 15 TC 83 Z9 83 U1 1 U2 34 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0743-7463 J9 LANGMUIR JI Langmuir PD JAN 23 PY 2001 VL 17 IS 2 BP 260 EP 264 DI 10.1021/la001273a PG 5 WC Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA 394HZ UT WOS:000166519100002 ER PT J AU Schwenke, DW AF Schwenke, DW TI A first principle effective Hamiltonian for including nonadiabatic effects for H-2(+) and HD+ SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID HYDROGEN MOLECULAR CATION; VIBRATION-ROTATION LEVELS; POTENTIAL-ENERGY SURFACE; BASIS-SETS; STATE; H2; D2 AB We compute nonadiabatic corrections for all bound and long-lived quasi-bound vibrational levels of H-2(+) and HD+ for selected rotational levels. This is done using the Bunker and Moss formalism with the correction factors computed from ab initio wave functions. The electronic wavefunctions are expanded in terms of nuclear centered Gaussian basis functions. The agreement with accurate calculations is very good: for H-2(+), the root-mean-square error in the computed dissociation energies is 0.0005 cm(-1), and, furthermore, most transition frequencies are predicted to within about 0.0001 cm(-1). For HD+, the results are not quite as good due to the uncertainties in the adiabatic correction. cm This paves the way for using these techniques to accurately predict the nonadiabatic effects for more complicated molecules. (C) 2001 American Institute of Physics. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Schwenke, DW (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RI schwenke, david/I-3564-2013 NR 18 TC 18 Z9 19 U1 0 U2 6 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 JAN 22 PY 2001 VL 114 IS 4 BP 1693 EP 1699 DI 10.1063/1.1334897 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 396QD UT WOS:000166647300028 ER PT J AU Nemiroff, RJ Marani, GF Norris, JP Bonnell, JT AF Nemiroff, RJ Marani, GF Norris, JP Bonnell, JT TI Limits on the cosmological abundance of supermassive compact objects from a millinensing search in gamma-ray burst data SO PHYSICAL REVIEW LETTERS LA English DT Article ID DARK-MATTER; GRB-990510; TELESCOPE; AFTERGLOW AB A new search for the gravitational lens effects of a significant cosmological density of supermassive compact objects (SCOs) on gamma-ray bursts (GRBs) has yielded a null result. We inspected the timing data of 774 BATSE-triggered GRBs for evidence of millilensing: repeated peaks similar in light-curve shape and spectra. Our null detection leads us to conclude that, in all candidate universes simulated, Omega (SCO) < 0.1 is favored for SCO masses in the range 10(5) < M-SCO/M. < 10(9), while in some universes and mass ranges the density limits are as much as 10 times lower. Therefore, a cosmologically significant population of SCOs near globular cluster mass did not come out of the primordial universe or condense at recombination. C1 Michigan Technol Univ, Dept Phys, Houghton, MI 49931 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Nemiroff, RJ (reprint author), Michigan Technol Univ, Dept Phys, 1400 Townsend Dr, Houghton, MI 49931 USA. NR 24 TC 17 Z9 17 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD JAN 22 PY 2001 VL 86 IS 4 BP 580 EP 583 DI 10.1103/PhysRevLett.86.580 PG 4 WC Physics, Multidisciplinary SC Physics GA 394TT UT WOS:000166539900006 PM 11177886 ER PT J AU Webster, CR Flesch, GJ Scott, DC Swanson, JE May, RD Woodward, WS Gmachl, C Capasso, F Sivco, DL Baillargeon, JN Hutchinson, AL Cho, AY AF Webster, CR Flesch, GJ Scott, DC Swanson, JE May, RD Woodward, WS Gmachl, C Capasso, F Sivco, DL Baillargeon, JN Hutchinson, AL Cho, AY TI Quantum-cascade laser measurements of stratospheric methane and nitrous oxide SO APPLIED OPTICS LA English DT Article ID ABSORPTION SPECTROMETER ALIAS; N2O; NO2; SPECTROSCOPY; OPERATION; CH4; BALLOON; HNO3; WAVE; HCL AB A tunable quantum-cascade (QC) laser has been flown on NASA's ER-2 high-altitude aircraft to produce the first atmospheric gas measurements with this newly invented device, an important milestone in the QC laser's future planetary, industrial, and commercial applications. Using a cryogenically cooled QC laser during a series of 20 aircraft flights beginning in September 1999 and extending through March 2000, we took measurements of methane (CH4) and nitrous oxide (N2O) gas up to similar to 20 km in the stratosphere over North America, Scandinavia, and Russia. The QC laser operating near an 8-mum wavelength was produced by the groups of Capasso and Cho of Bell Laboratories, Lucent Technologies, where QC lasers were invented in 1994. Compared with its companion lead salt diode lasers that were also flown on these flights, the single-made QC laser cooled to 82 K and produced higher output power (10 mW), narrower laser linewidth (17 MHz), increased measurement precision (a factor of 3), and better spectral stability (similar to0.1 cm(-1) K). The sensitivity of the QC laser channel was estimated to correspond to a minimum-detectable mixing ratio for methane of approximately 2 parts per billion by volume. (C) 2001 Optical Society of America OCIS codes: 010.0010, 120.0120, 140.0140, 300.0300. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Bell Labs, Lucent Technol, Murray Hill, NJ 07974 USA. RP Webster, CR (reprint author), CALTECH, Jet Prop Lab, MS 183 401,4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM Chris.R.Webster@jpl.nasa.gov NR 19 TC 80 Z9 80 U1 0 U2 14 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 JAN 20 PY 2001 VL 40 IS 3 BP 321 EP 326 DI 10.1364/AO.40.000321 PG 6 WC Optics SC Optics GA 392UB UT WOS:000166430000001 PM 18357003 ER PT J AU Wright, CW Hoge, FE Swift, RN Yungel, JK Schirtzinger, CR AF Wright, CW Hoge, FE Swift, RN Yungel, JK Schirtzinger, CR TI Next-generation NASA airborne oceanographic lidar system SO APPLIED OPTICS LA English DT Article ID INHERENT OPTICAL-PROPERTIES; PASSIVE CORRELATION SPECTROSCOPY; DISSOLVED ORGANIC-MATTER; EQUATORIAL PACIFIC-OCEAN; SATELLITE RETRIEVAL; ABSORPTION-COEFFICIENT; COLOR MEASUREMENT; RADIANCE MODEL; FLUORESCENCE; BACKSCATTER AB The complete design and flight test of the next-generation Airborne Oceanographic Lidar (AOL-3) is detailed. The application of new technology has allowed major reductions in weight, volume, and power requirements compared with the earlier AOL sensor. Subsystem designs for the new AOL sensor include new technology in fiber optics, spectrometer detector optical train, miniature photomultiplier modules, dual-laser wavelength excitation from a single small laser source, and new receiver optical configuration. The new design reduced telescope size and maintained the same principal fluorescence and water Raman bands but essentially retained a comparable measurement accuracy. A major advancement is the implementation of single-laser simultaneous excitation of two physically separate oceanic target areas: one stimulated by 532 nm and the other by 355 nm. Backscattered fluorescence and Raman signals from both targets are acquired simultaneously by use of the same telescope and spectrometer-detector system. Two digital oscilloscopes provide temporal- and depth-resolved data from each of seven spectral emission bands. (C) 2001 Optical Society of America OCIS codes: 280.0280, 010.3640, 010.4450. C1 Wallops Flight Facil, Wallops Isl, VA 23337 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EG&G Inc, Wellesley, MA 02481 USA. RP Wright, CW (reprint author), Wallops Flight Facil, Wallops Isl, VA 23337 USA. EM wright@osb1.wff.nasa.gov NR 18 TC 23 Z9 27 U1 0 U2 4 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 JAN 20 PY 2001 VL 40 IS 3 BP 336 EP 342 DI 10.1364/AO.40.000336 PG 7 WC Optics SC Optics GA 392UB UT WOS:000166430000004 PM 18357006 ER PT J AU Wang, MH Franz, BA Barnes, RA McClain, CR AF Wang, MH Franz, BA Barnes, RA McClain, CR TI Effects of spectral bandpass on SeaWiFS-retrieved near-surface optical properties of the ocean SO APPLIED OPTICS LA English DT Article ID WATER-LEAVING RADIANCE; ATMOSPHERIC CORRECTION; COLOR; REFLECTANCE; WHITECAPS; ALGORITHM; IMAGERY AB A simple correction method to remove the spectral bandpass effects of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) on the derived normalized water-leaving radiances and ocean-near-surface chlorophyll concentration is developed and implemented in the SeaWiFS data-processing system. SeaWiFS has not only in-band response structures but also significant sensor out-of-band contributions. The effects of the SeaWiFS out-of-band contribution at the green bands is particularly significant for the derived normalized water-leaving radiances and therefore for the retrieved ocean-near-surface chlorophyll concentration. With the sensor spectral bandpass corrections, the low chlorophyll concentration is even lower in the clear ocean regions, whereas there are almost no changes for the oceans with a chlorophyll concentration of >0.2 mg/m(3). (C) 2001 Optical Society of America OCIS codes: 010.4450, 010.1310, 280.0280. C1 Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Gen Sci Corp, Beltsville, MD 20705 USA. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Wang, MH (reprint author), Univ Maryland Baltimore Cty, NASA, Goddard Space Flight Ctr, Code 970-2, Greenbelt, MD 20771 USA. EM wang@simbios.gsfc.nasa.gov RI Wang, Menghua/F-5631-2010; Franz, Bryan/D-6284-2012 OI Wang, Menghua/0000-0001-7019-3125; Franz, Bryan/0000-0003-0293-2082 NR 14 TC 30 Z9 33 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 JAN 20 PY 2001 VL 40 IS 3 BP 343 EP 348 DI 10.1364/AO.40.000343 PG 6 WC Optics SC Optics GA 392UB UT WOS:000166430000005 PM 18357007 ER PT J AU Sarkisov, SS Diggs, DE Adamovsky, G Curley, MJ AF Sarkisov, SS Diggs, DE Adamovsky, G Curley, MJ TI Single-arm double-mode double-order planar waveguide interferometric sensor SO APPLIED OPTICS LA English DT Article ID PROBE; FILMS; FIBER AB A sensor is described for which interference measurements of the phase delay between two propagating modes of different orders in a slab thin-film waveguide are used as the sensing technique. The basic building block of the sensor is a polymer film doped with an indicator dye such as Bromocresol Purple. The modes of two orders such as TM, and TM, are simultaneously excited in the Light-guiding film with a focusing optics and a prism coupler. The modes are decoupled from the film and recombined to produce an interference pattern in the face of an output optical fiber. The sensitivity of the sensor to the ambient temperature change is 1.5 degreesC, and the sensitivity to NH3 is 200 parts in 10(6) for one full oscillation of the signal. (C) 2001 Optical Society of America OCIS codes: 130.6010, 130.2790, 130.3120, 120.3180. C1 Alabama A&M Univ, Dept Phys, Normal, AL 35762 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Sarkisov, SS (reprint author), Alabama A&M Univ, Dept Phys, POB 1268, Normal, AL 35762 USA. EM sergei@caos.aamu.edu; grigory.adamovsky@lerc.nasa.gov; mcurley@aamu.edu NR 22 TC 17 Z9 17 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 JAN 20 PY 2001 VL 40 IS 3 BP 349 EP 359 DI 10.1364/AO.40.000349 PG 11 WC Optics SC Optics GA 392UB UT WOS:000166430000006 PM 18357008 ER PT J AU Whiteman, DN Schwemmer, G Berkoff, T Plotkin, H Ramos-Izquierdo, L Pappalardo, G AF Whiteman, DN Schwemmer, G Berkoff, T Plotkin, H Ramos-Izquierdo, L Pappalardo, G TI Performance modeling of an airborne Raman water-vapor lidar SO APPLIED OPTICS LA English DT Article ID TEMPERATURE-MEASUREMENTS; CROSS-SECTIONS; BACKSCATTER; AEROSOLS; CLOUD AB We have developed a sophisticated Raman lidar numerical model to simulate the performance of two ground-based Raman water-vapor lidar systems. After verifying the model using these ground-based measurements, we then used the model to simulate the water-vapor measurement capability of an airborne Raman lidar under both daytime and nighttime conditions for a wide range of water-vapor conditions. The results indicate that, under many circumstances, the daytime measurements possess comparable quality to an existing airborne differential absorption water-vapor lidar whereas the nighttime measurements have improved spatial and temporal resolution. In addition, an airborne Raman lidar can offer measurements that are difficult or impossible with the differential absorption lidar technique. OCIS codes: 280.3640, 010.3920, 120.4820, 280.1810, 290.5860. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Joint Ctr Earth Sensing Technol, Baltimore, MD 21250 USA. Univ Maryland Baltimore Cty, Goddard Earth Sci & Technol Ctr, Baltimore, MD 21250 USA. Sci Syst & Applicat Inc, Lanham, MD 20706 USA. Natl Res Council Italy, I-85100 Potenza, Italy. RP Whiteman, DN (reprint author), NASA, Goddard Space Flight Ctr, Bldg 33, Greenbelt, MD 20771 USA. EM david.whiteman@gsfc.nasa.gov NR 24 TC 18 Z9 20 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 JAN 20 PY 2001 VL 40 IS 3 BP 375 EP 390 DI 10.1364/AO.40.000375 PG 16 WC Optics SC Optics GA 392UB UT WOS:000166430000009 PM 18357011 ER PT J AU Brown, BA Bregman, JN AF Brown, BA Bregman, JN TI Emission mechanisms in X-raye-faint galaxies SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : elliptical and lenticular, cD galaxies : ISM; galaxies : stellar content; X-rays : galaxies; X-rays : ISM ID ROSAT PSPC OBSERVATIONS; ELLIPTIC GALAXIES; SPECTRAL PROPERTIES; INTERSTELLAR-MEDIUM; COMPLETE SAMPLE; GAS; ASCA; PHOTOMETRY; HALO AB Hot gas dominates the emission in X-ray-luminous early-type galaxies, but in relatively X-ray-faint systems, integrated X-ray emission from discrete stellar-like sources is thought to be considerable, although the amount of the contribution is controversial. To help resolve this issue, we examine the radial X-ray surface brightness distribution of 17 X-ray-faint galaxies observed with the ROSAT HRI and PSPC. We assume that the stellar contribution follows a de Vaucouleurs law while the hot gas component follows a King beta model. For some galaxies, both models Dt equally well, but for a number of systems, a dual component model yields the best Dt, from which upper bounds are placed on the stellar contribution. Best-Dt values for the stellar contribution are inconsistent with (lower than) that suggested by Fabbiano, Gioia, & Trinchieri and estimated from the bulge of M31 but are consistent with the Forman, Jones, & Tucker estimate of the stellar fraction in X-ray-faint elliptical and S0 galaxies. Our results indicate an upper limit to discrete sources of L(X)/L(B) = 1.6 x 10(29) ergs s(-1) L(.)(-1). C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA. RP Brown, BA (reprint author), NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. EM Beth.Brown@gsfc.nasa.gov; jbregman@umich.edu NR 33 TC 14 Z9 14 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 JAN 20 PY 2001 VL 547 IS 1 BP 154 EP 161 DI 10.1086/318353 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 395RN UT WOS:000166595200017 ER PT J AU Jones, FC Lukasiak, A Ptuskin, V Webber, W AF Jones, FC Lukasiak, A Ptuskin, V Webber, W TI The modified weighted slab technique: Models and results SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmic rays; diffusion; magnetic fields; shock waves ID LIQUID-HYDROGEN TARGET; PRODUCTION CROSS-SECTIONS; COSMIC-RAY ANISOTROPY; SUPERNOVA-REMNANTS; RELATIVISTIC NUCLEI; INTERSTELLAR-MEDIUM; SHOCK ACCELERATION; TRANSPORT; GALAXY; NE-22 AB In an attempt to understand the source and propagation of Galactic cosmic rays, we have employed the modified weighted slab technique along with recent values of the relevant cross sections to compute primary to secondary ratios including B/C and sub-Fe/Fe for different Galactic propagation models. The models that we have considered are the disk-halo diffusion model, the dynamical halo wind model, the turbulent diffusion model, and a model with minimal reacceleration. The modified weighted slab technique will be briefly discussed and a more detailed description of the models will be given. We will also discuss the impact that the various models have on the problem of anisotropy at high energy and discuss what properties of a particular model bear on this issue. C1 NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Greenbelt, MD 20771 USA. Univ Maryland, Inst Phys Sci & Technol, College Pk, MD 20742 USA. Russian Acad Sci, Inst Terr Magnetism Ionosphere & Radio Wave P, IZMIRAN, Troitsk 142092, Moscow Region, Russia. New Mexico State Univ, Las Cruces, NM 88003 USA. RP Jones, FC (reprint author), NASA, Goddard Space Flight Ctr, High Energy Astrophys Lab, Code 661, Greenbelt, MD 20771 USA. NR 35 TC 97 Z9 98 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 JAN 20 PY 2001 VL 547 IS 1 BP 264 EP 271 DI 10.1086/318358 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 395RN UT WOS:000166595200027 ER PT J AU Mitrofanov, IG Litvak, ML Anfimov, DS Sanin, AB Briggs, MS Paciesas, WS Pendleton, GN Preece, RD Meegan, CA AF Mitrofanov, IG Litvak, ML Anfimov, DS Sanin, AB Briggs, MS Paciesas, WS Pendleton, GN Preece, RD Meegan, CA TI Generic difference between early and late stages of BATSE gamma-ray bursts SO ASTROPHYSICAL JOURNAL LA English DT Article DE gamma rays : bursts ID TIME AB The early and late stages of gamma-ray bursts are studied in a statistical analysis of the large sample of long BATSE events. The primary peak is used as the boundary between the early and late stages of emission. Significant differences are found between the stages : the early stage is shorter, it has harder emission, and it becomes a smaller fraction of the total burst duration for burst groups of decreasing intensity. C1 Moscow Space Res Inst, Moscow 117810, Russia. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Mitrofanov, IG (reprint author), Moscow Space Res Inst, Profsojuznaya Str 84-32, Moscow 117810, Russia. OI Preece, Robert/0000-0003-1626-7335 NR 13 TC 0 Z9 0 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 JAN 20 PY 2001 VL 547 IS 1 BP 334 EP 337 DI 10.1086/318347 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 395RN UT WOS:000166595200035 ER PT J AU Lentz, EJ Baron, E Lundqvist, P Branch, D Hauschildt, PH Fransson, C Garnavich, P Bastian, N Filippenko, AV Kirshner, RP Challis, PM Jha, S Leibundgut, B McCray, R Michael, E Panagia, N Phillips, MM Pun, CSJ Schmidt, B Sonneborn, G Suntzeff, NB Wang, L Wheeler, JC AF Lentz, EJ Baron, E Lundqvist, P Branch, D Hauschildt, PH Fransson, C Garnavich, P Bastian, N Filippenko, AV Kirshner, RP Challis, PM Jha, S Leibundgut, B McCray, R Michael, E Panagia, N Phillips, MM Pun, CSJ Schmidt, B Sonneborn, G Suntzeff, NB Wang, L Wheeler, JC TI Analysis of type IInSN1998S: Effects of circumstellar interaction on observed spectra SO ASTROPHYSICAL JOURNAL LA English DT Article DE radiative transfer; supernovae : individual (SN 1998S) ID SUPERNOVAE AB We present spectral analysis of early observations of the Type IIn supernova 1998S using the general non-local thermodynamic equilibrium atmosphere code PHOENIX. We model both the underlying supernova spectrum and the overlying circumstellar interaction region and produce spectra in good agreement with observations. The early spectra are well fitted by lines produced primarily in the circumstellar region itself, and later spectra are due primarily to the supernova ejecta. Intermediate spectra are affected by both regions. A mass-loss rate of order (M) over dot similar to 0.0001-0.001 M. yr(-1) is inferred for a wind speed of 100-1000 km s(-1). We discuss how future self-consistent models will better clarify the underlying progenitor structure. C1 Univ Oklahoma, Dept Phys & Astron, Norman, OK 73019 USA. Stockholm Observ, SE-13336 Saltsjobaden, Sweden. Univ Georgia, Dept Phys & Astron, Athens, GA 30602 USA. Univ Georgia, Ctr Simulat Phys, Athens, GA 30602 USA. Univ Notre Dame, Dept Phys, Notre Dame, IN USA. Univ Wisconsin, Dept Astron, Madison, WI 53706 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 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 Creek PO, ACT 2611, Australia. Cerro Tololo Interamer Observ, Natl Opt Astron Observ, La Serena, Chile. Univ Texas, Dept Astron, Austin, TX 78712 USA. RP Lentz, EJ (reprint author), Univ Oklahoma, Dept Phys & Astron, Norman, OK 73019 USA. RI Baron, Edward/A-9041-2009; Sonneborn, George/D-5255-2012; Lentz, Eric/M-7173-2015; OI Baron, Edward/0000-0001-5393-1608; Lentz, Eric/0000-0002-5231-0532; Schmidt, Brian/0000-0001-6589-1287 NR 20 TC 26 Z9 26 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 JAN 20 PY 2001 VL 547 IS 1 BP 406 EP 411 DI 10.1086/318363 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 395RN UT WOS:000166595200042 ER PT J AU Marsden, D Lingenfelter, RE Rothschild, RE AF Marsden, D Lingenfelter, RE Rothschild, RE TI Does pulsar B1757-24 have a fallback disk? SO ASTROPHYSICAL JOURNAL LA English DT Article DE pulsars : individual (PSR B1757-24); stars : neutron; supernova remnants ID X-RAY PULSARS; SUPERNOVA-REMNANTS; BLACK-HOLE; STAR; ACCRETION; G5.4-1.2 AB Radio pulsars are thought to spin down primarily as a result of torque from magnetic dipole radiation (MDR) emitted by the time-varying stellar magnetic field as the star rotates. This assumption yields a "characteristic age" for a pulsar, which has generally been assumed to be comparable to the actual age. Recent observational limits on the proper motion of pulsar B1757-24, however, revealed that the actual age (>39 kyr) of this pulsar is much greater than its MDR characteristic age (16 kyr), calling into question the assumption of pure MDR spin-down for this and other pulsars. To explore the possible cause of this discrepancy, we consider a scenario in which the pulsar acquired an accretion disk from supernova ejecta and the subsequent spin-down occurred under the combined action of MDR and accretion torques. A simplified model of the accretion torque involving a constant mass inflow rate at the pulsar magnetosphere can explain the age and period derivative of the pulsar for reasonable values of the pulsar magnetic field and inflow rate. We discuss testable predictions of this model. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif San Diego, Ctr Astrophys & Space Sci, La Jolla, CA 92093 USA. RP Marsden, D (reprint author), NASA, Goddard Space Flight Ctr, Code 662, Greenbelt, MD 20771 USA. NR 34 TC 28 Z9 30 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 JAN 20 PY 2001 VL 547 IS 1 BP L45 EP L48 DI 10.1086/318881 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 395RT UT WOS:000166595600011 ER PT J AU Steglich, C Behrenfeld, M Koblizek, M Claustre, H Penno, S Prasil, O Partensky, F Hess, WR AF Steglich, C Behrenfeld, M Koblizek, M Claustre, H Penno, S Prasil, O Partensky, F Hess, WR TI Nitrogen deprivation strongly affects Photosystem II but not phycoerythrin level in the divinyl-chlorophyll b-containing cyanobacterium Prochlorococcus marinus SO BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS LA English DT Article DE cyanobacteria; phycoerythrin; photosynthesis; light-harvesting complex; variable fluorescence; nitrogen deprivation ID SYNECHOCOCCUS; FLUORESCENCE; LIGHT; PHYTOPLANKTON; CAROTENOIDS; PROKARYOTE; PHYSIOLOGY; CHLOROSIS; PCC-7942; ANTENNA AB Effects of nitrogen limitation on Photosystem II (PSII) activities and on phycoerythrin were studied in batch cultures of the marine oxyphotobacterium Prochlorococcus marinus. Dramatic decreases in photochemical quantum yields (F-V/F-M), the amplitude of thermoluminescence (TL) B-band, and the rate of QA reoxidation were observed within 12 h of growth in nitrogen-limited conditions. The decline in F-V/F-M paralleled changes in the TL B-band amplitude, indicative of losses in PSII activities and formation of non-functional PSII centers. These changes were accompanied by a continuous reduction in D1 protein content. In contrast, nitrogen deprivation did not cause any significant reduction in phycoerythrin content. Our results refute phycoerythrin as a nitrogen storage complex in Prochlorococcus. Regulation of phycoerythrin gene expression in Prochlorococcus is different from that in typical phycobilisome-containing cyanobacteria and eukaryotic algae investigated so far. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Humboldt Univ, Dept Biol, D-10115 Berlin, Germany. US NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Ctr Photosynth, Inst Microbiol, Trebon 37981, Czech Republic. Univ Paris 06, F-06238 Villefranche Sur Mer, France. INSU, CNRS, Phys & Chim Marines Lab, F-06238 Villefranche Sur Mer, France. Interuniv Inst Marine Sci, H Steinitz Marine Biol Lab, IL-88103 Eilat, Israel. INSU, CNRS, Biol Stn, F-29682 Roscoff, France. Univ Paris 06, F-29682 Roscoff, France. RP Hess, WR (reprint author), Humboldt Univ, Dept Biol, Chausseestr 117, D-10115 Berlin, Germany. RI Prasil, Ondrej/H-2454-2014; Koblizek, Michal/H-2851-2014; CLAUSTRE, Herve/E-6877-2011; OI Prasil, Ondrej/0000-0002-0012-4359; CLAUSTRE, Herve/0000-0001-6243-0258; Partensky, Frederic/0000-0003-1274-4050 NR 34 TC 26 Z9 29 U1 2 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0005-2728 J9 BBA-BIOENERGETICS JI Biochim. Biophys. Acta-Bioenerg. PD JAN 19 PY 2001 VL 1503 IS 3 BP 341 EP 349 DI 10.1016/S0005-2728(00)00211-5 PG 9 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA 389HT UT WOS:000166233100008 PM 11115645 ER PT J AU Des Marais, DJ AF Des Marais, DJ TI On the origins of photosynthesis - Response SO SCIENCE LA English DT Letter ID EVOLUTION; OXYGEN C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Des Marais, DJ (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 11 TC 0 Z9 0 U1 2 U2 7 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 JAN 19 PY 2001 VL 291 IS 5503 BP 437 EP 437 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 393UF UT WOS:000166487500021 ER PT J AU Crisp, D AF Crisp, D TI Planetary science - The nightside of Venus SO SCIENCE LA English DT Editorial Material ID AIRGLOW; EMISSION; OXYGEN C1 NASA, New Millennium Program, Jet Prop Lab, Pasadena, CA 91109 USA. RP Crisp, D (reprint author), NASA, New Millennium Program, Jet Prop Lab, Pasadena, CA 91109 USA. NR 9 TC 1 Z9 1 U1 0 U2 0 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 JAN 19 PY 2001 VL 291 IS 5503 BP 444 EP 445 DI 10.1126/science.1057630 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 393UF UT WOS:000166487500028 PM 11228142 ER PT J AU Gurnett, DA Zarka, P Manning, R Kurth, WS Hospodarsky, GB Averkamp, TF Kaiser, ML Farrell, WM AF Gurnett, DA Zarka, P Manning, R Kurth, WS Hospodarsky, GB Averkamp, TF Kaiser, ML Farrell, WM TI Non-detection at Venus of high-frequency radio signals characteristic of terrestrial lightning SO NATURE LA English DT Article ID SPRITES94 AIRCRAFT CAMPAIGN AB The detection(1,2) of impulsive low-frequency (10 to 80 kHz) radio signals, and separate very-low-frequency (similar to 100 Hz) radio 'whistler' signals(3-5) provided the first evidence for lightning in the atmosphere of Venus. Later, a small number of impulsive high-frequency (100 kHz to 5.6 MHz) radio signals, possibly due to lightning, were also detected(6). The existence of lightning at Venus has, however, remained controversial(7-13). Here we report the results of a search for high-frequency (0.125 to 16 MHz) radio signals during two close fly-bys of Venus by the Cassini spacecraft. Such signals are characteristic of terrestrial lightning, and are commonly heard on AM (amplitude-modulated) radios during thunderstorms. Although the instrument easily detected signals from terrestrial lightning during a later fly-by of Earth (at a global flash rate estimated to be 70 s(-1), which is consistent with the rate expected for terrestrial lightning), no similar signals were detected from Venus. If lightning exists in the venusian atmosphere, it is either extremely rare, or very different from terrestrial lightning. C1 Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. Observ Paris, Space Res Dept, CNRS, UMR 8632, Meudon, France. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Gurnett, DA (reprint author), Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA. RI Farrell, William/I-4865-2013; OI Hospodarsky, George/0000-0001-9200-9878; Kurth, William/0000-0002-5471-6202 NR 20 TC 47 Z9 48 U1 0 U2 3 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JAN 18 PY 2001 VL 409 IS 6818 BP 313 EP 315 DI 10.1038/35053009 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 392VY UT WOS:000166434300038 PM 11201733 ER PT J AU Adams, PJ Seinfeld, JH Koch, D Mickley, L Jacob, D AF Adams, PJ Seinfeld, JH Koch, D Mickley, L Jacob, D TI General circulation model assessment of direct radiative forcing by the sulfate-nitrate-ammonium-water inorganic aerosol system SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTHROPOGENIC SULFATE; ATMOSPHERIC AEROSOLS; TROPOSPHERIC OZONE; GLOBAL SIMULATION; LIGHT-SCATTERING; 3-DIMENSIONAL MODEL; RELATIVE-HUMIDITY; GREENHOUSE GASES; CLIMATE MODEL; SULFUR CYCLE AB An on-line simulation of aerosol sulfate, nitrate, ammonium, and water in the Goddard Institute for Space Studies general circulation model (GCM II-prime) has been used to estimate direct aerosol radiative forcing for the years 1800, 2000, and 2100. This is the first direct forcing estimate based on the equilibrium water content of a changing SO(4)(2-)NO(3)(-)-NH(4)(+) mixture and the first estimate of nitrate forcing based on a global model of nitrate aerosol, Present-day global and annual average anthropogenic direct forcing is estimated to be -0.95 and -0.19 W/m(2) for sulfate and nitrate, respectively. Simulations with a future emissions scenario indicate that nitrate forcing could increase to -1.28 W/m(2) by 2100, while sulfate forcing declines to -0.85 W/m(2). This result shows that future estimates of aerosol forcing based solely on predicted sulfate concentrations may be misleading and that the potential for significant concentrations of ammonium nitrate needs to be considered in estimates of future climate change. Calculated direct aerosol forcing is highly sensitive to the model treatment of water uptake. By calculating the equilibrium water content of a SO(4)(2-)-NH(4)(+) aerosol mixture and the optical properties of the wet aerosol, we estimate a forcing that is almost 35% greater than that derived from correcting a low relative humidity scattering coefficient with an empirical f(RH) factor. The discrepancy stems from the failure of the empirical parameterization to adequately account for water uptake above about 90% relative humidity. These results suggest that water uptake above 90% RH may make a substantial contribution to average direct forcing, although subgrid-scale variability makes it difficult to represent humid areas in a GCM. C1 CALTECH, Dept Chem, Pasadena, CA 91125 USA. NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Harvard Univ, Div Engn & Appl Sci, Cambridge, MA 02138 USA. RP Adams, PJ (reprint author), CALTECH, Dept Chem, 104-44, Pasadena, CA 91125 USA. EM petera@its.caltech.edu; seinfeld@caltech.edu RI Mickley, Loretta/D-2021-2012; Adams, Peter/D-7134-2013 OI Mickley, Loretta/0000-0002-7859-3470; Adams, Peter/0000-0003-0041-058X NR 53 TC 142 Z9 146 U1 2 U2 27 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 JAN 16 PY 2001 VL 106 IS D1 BP 1097 EP 1111 DI 10.1029/2000JD900512 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 393FL UT WOS:000166458500001 ER PT J AU Kursinski, ER Hajj, GA AF Kursinski, ER Hajj, GA TI A comparison of water vapor derived from GPS occultations and global weather analyses SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID RADIO OCCULTATION; POSITIONING SYSTEM; EARTHS ATMOSPHERE; VARIATIONAL ANALYSIS; CLIMATOLOGY; INFORMATION; TROPOSPHERE; RADIANCES; HUMIDITY AB Despite its fundamental importance in radiative transfer, atmospheric dynamics, and the hydrological cycle, atmospheric water is inadequately characterized particularly at a global scale. Occultation measurements from the Global Positioning System (GPS) should improve upon this situation. Individual occultations yield profiles of specific humidity accurate to 0.2 to 0.5 g/kg providing sensitive measurements of lower and middle tropospheric water vapor with global coverage in a unique, all-weather, limb-viewing geometry with several hundred meters to a kilometer vertical resolution. We have derived water vapor profiles from June 21 to July 4, 1995, using GPS occultation data combined with global temperature analyses from the European Center for Medium-Range Weather Forecasts (ECMWF) and reanalyses from the National Centers for Environmental Prediction (NCEP). The zonal mean structure of the profiles exhibits basic climatological features of tropospheric moisture. Specific humidity biases between the GPS results and the ECMWF global humidity analyses in the middle to upper troposphere are similar to0.1 g/kg or less. Occultation results below 6 km altitude are generally drier than those of ECMWF with the bias generally increasing toward warmer temperatures. Near the height of the trade wind inversion, the ECMWF analyses are significantly moister than the occultation results due to vertical smoothing and overextension of the boundary layer top in the analyses. Overall, the occultation results are drier than the NCEP reanalyses with a marked exception near the Intertropical Convergence Zone (ITCZ) where occultation results are wetter by more than 10%. The occultation results are significantly wetter near the ITCZ and drier in the subtropics than the classical moisture climatology of Peixoto and Oort. Similarities between the NCEP and the Peixoto and Oort near-ITCZ differences suggest that a common analysis/model problem may be responsible. The generally wetter Peixoto and Oort results in the subtropics are due in part to moist radiosonde biases. Discrepancies between these data sets are significant and limit our ability to resolve uncertainties in moisture control and feedbacks in a changing climate. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kursinski, ER (reprint author), CALTECH, Jet Prop Lab, MS 238-600, Pasadena, CA 91109 USA. NR 32 TC 58 Z9 61 U1 0 U2 2 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 JAN 16 PY 2001 VL 106 IS D1 BP 1113 EP 1138 DI 10.1029/2000JD900421 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA 393FL UT WOS:000166458500002 ER PT J AU Martin, JML Bauschlicher, CW Ricca, A AF Martin, JML Bauschlicher, CW Ricca, A TI On the integration accuracy in molecular density functional theory calculations using Gaussian basis sets SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article ID INHOMOGENEOUS ELECTRON-GAS; NUMERICAL-INTEGRATION; CORRELATION-ENERGY; 2ND DERIVATIVES; EXCHANGE; APPROXIMATION; POTENTIALS AB The sensitivity of computed DFT (Density Functional Theory) molecular properties (including energetics, geometries, vibrational frequencies, and infrared intensities) to the radial and angular numerical integration grid meshes, as well as to the partitioning scheme, is discussed for a number of molecules using the Gaussian 98 program system. Problems with typical production grid sizes are particularly acute for third-row transition metal systems, but may still result in qualitatively incorrect results for a molecule as simple as CCH. Practical recommendations are made with respect to grid choices for the energy (+ gradient) steps, as well as for the solution of the CPKS (Coupled Perturbed Kohn-Sham) equations. (C) 2001 Elsevier Science B.V. All rights reserved. C1 Weizmann Inst Sci, Dept Organ Chem, IL-76100 Rehovot, Israel. NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, ELORET, Moffett Field, CA 94035 USA. RP Martin, JML (reprint author), Weizmann Inst Sci, Dept Organ Chem, Kimmelman Bldg,Room 262, IL-76100 Rehovot, Israel. EM comartin@wicc.weizmann.ac.il RI Martin, Jan/A-7457-2008 OI Martin, Jan/0000-0002-0005-5074 NR 31 TC 103 Z9 104 U1 1 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 EI 1879-2944 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD JAN 15 PY 2001 VL 133 IS 2-3 BP 189 EP 201 DI 10.1016/S0010-4655(00)00174-0 PG 13 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA 391AZ UT WOS:000166333100005 ER PT J AU Davis, DD Grodzinsky, G Kasibhatla, P Crawford, J Chen, G Liu, S Bandy, A Thornton, D Guan, H Sandholm, S AF Davis, DD Grodzinsky, G Kasibhatla, P Crawford, J Chen, G Liu, S Bandy, A Thornton, D Guan, H Sandholm, S TI Impact of ship emissions on marine boundary layer NOx and SO2 distributions over the Pacific basin SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID AIRBORNE MEASUREMENTS; SULFUR-DIOXIDE; CLIMATE AB The impact of ship emissions on marine boundary layer (MBL) NOx and SO2 levels over the Pacific Ocean has been explored by comparing predictions (with and without ships) from a global chemical transport model (GCTM) against compiled airborne observations of MBL NOx and SO2. For latitudes >15 degreesN, which define that part of the Pacific having the heaviest shipping, this analysis revealed significant model over prediction for NOx and a modest under prediction for SO2 when ship emissions were considered. Possible reasons for the difference in NOx and SO2 were explored using a full-chemistry box model. These results revealed that for an actual plume setting the NO2 lifetime could be greatly shortened by chemical processes promoted by ship plume emissions themselves. Similar chemical behavior was not found for SO2. C1 Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. Duke Univ, Nicholas Sch Environm, Durham, NC USA. NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23665 USA. Drexel Univ, Dept Chem, Philadelphia, PA 19104 USA. RP Davis, DD (reprint author), Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA. RI Kasibhatla, Prasad/A-2574-2010; Crawford, James/L-6632-2013 OI Crawford, James/0000-0002-6982-0934 NR 16 TC 41 Z9 43 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 JAN 15 PY 2001 VL 28 IS 2 BP 235 EP 238 DI 10.1029/2000GL012013 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 392MN UT WOS:000166415400010 ER PT J AU Chowdhary, J Cairns, B Mishchenko, M Travis, L AF Chowdhary, J Cairns, B Mishchenko, M Travis, L TI Retrieval of aerosol properties over the ocean using multispectral and multiangle photopolarimetric measurements from the Research Scanning Polarimeter SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SPECTRAL RADIANCES; REFLECTED SUNLIGHT; ALGORITHM; INFORMATION; SENSITIVITY; VALIDATION; SCATTERING; SATELLITE; LIGHT; AVHRR AB The evaluation of the direct and indirect aerosol forcings of climate requires precise knowledge of the aerosol optical thickness, size distribution, chemical composition, and number density. Global monitoring of these parameters from satellites requires instruments that make full use of the information content of the scattered solar radiation. In this paper we analyze multispectral and multiangle photopolarimetric observations performed with an airborne version of the Earth Observing Scanning Polarimeter over the ocean and demonstrate their exceptional retrieval potential. Using the 0.865- and 2.250-mum channels, we are able to determine the parameters of a bimodal size distribution, identify the presence of water-soluble and sea salt particles, and retrieve the optical thickness and column number density of aerosols. We also demonstrate that less comprehensive measurements by existing instruments would fail to provide retrievals of comparable completeness and accuracy. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Columbia Univ, Dept Appl Phys & Appl Math, New York, NY USA. RP NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. EM jchowdhary@giss.nasa.gov; bcairns@giss.nasa.gov; mmishchenko@giss.nasa.gov; ltravis@giss.nasa.gov RI Mishchenko, Michael/D-4426-2012 NR 28 TC 87 Z9 88 U1 2 U2 13 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 JAN 15 PY 2001 VL 28 IS 2 BP 243 EP 246 DI 10.1029/2000GL011783 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 392MN UT WOS:000166415400012 ER PT J AU Robertson, FR Spencer, RW Fitzjarrald, DE AF Robertson, FR Spencer, RW Fitzjarrald, DE TI A new satellite deep convective ice index for tropical climate monitoring: Possible implications for existing oceanic precipitation data sets SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SNOW COVER; RAINFALL; MODEL; CLIMATOLOGIES; RETRIEVAL AB The tropical atmosphere is continually overturning, with deep moist convective cloud systems exporting energy from the subcloud layer and depositing it in the upper troposphere. A new satellite index of this deep convective activity is based upon measurements of large ice particles in the upper portions of tropical convective complexes. This 20-year record reveals a strong signal of the El Nino Southern Oscillation (ENSO), with 10 to 15 % upward (downward) swings in the deep convective index during El Nino (La Nina). Warming of tropical sea surface temperatures (SST), whether from anthropogenically-produced greenhouse gases or natural climate variability, is expected to be associated with more convective overturning of the atmosphere. While other tropical precipitation climatologies vary dramatically in their support of this relationship, the present deep convective ice (DCI) index shows a strong correlation between interannual variations of tropical convection and SST. C1 NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, Huntsville, AL 35806 USA. RP Robertson, FR (reprint author), NASA, George C Marshall Space Flight Ctr, Global Hydrol & Climate Ctr, 977 Explorer Blvd, Huntsville, AL 35806 USA. NR 19 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 JAN 15 PY 2001 VL 28 IS 2 BP 251 EP 254 DI 10.1029/2000GL011892 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 392MN UT WOS:000166415400014 ER PT J AU Czekala, H Crewell, S Simmer, C Thiele, A AF Czekala, H Crewell, S Simmer, C Thiele, A TI Discrimination of cloud and rain liquid water path by groundbased polarized microwave radiometry SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VAPOR AB We propose a new approach for groundbased remote sensing of liquid water path (LWP) in the presence of precipitating clouds. Dual polarized groundbased microwave radiometers are capable of detecting the unique scattering signature of nonspherical precipitation sized particles. This polarization signal is only produced by the precipitation particles for which the brightness temperature emission has a different sensitivity to LWP than the smaller cloud drops. By using the information that is contained in the polarization difference of the downwelling brightness temperature the cloud and rain liquid water fractions can be estimated independently. Future retrieval algorithms based on our proposed approach will enable the detection of small precipitation fractions in thick clouds and also allow for estimates of cloud and rain LWP in raining conditions. C1 Columbia Univ, NASA, Goddard Inst Space Studies, Dept Appl Phys, New York, NY 10025 USA. Univ Bonn, Inst Meteorol, D-53121 Bonn, Germany. RP Czekala, H (reprint author), Columbia Univ, NASA, Goddard Inst Space Studies, Dept Appl Phys, 2880 Broadway, New York, NY 10025 USA. RI Simmer, Clemens/M-4949-2013; Crewell, Susanne/O-1640-2013 OI Simmer, Clemens/0000-0003-3001-8642; Crewell, Susanne/0000-0003-1251-5805 NR 9 TC 19 Z9 19 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 JAN 15 PY 2001 VL 28 IS 2 BP 267 EP 270 DI 10.1029/2000GL012247 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 392MN UT WOS:000166415400018 ER PT J AU Perlwitz, J Graf, HF AF Perlwitz, J Graf, HF TI Troposphere-stratosphere dynamic coupling under strong and weak polar vortex conditions SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NORTHERN-HEMISPHERE; PLANETARY-WAVES; CIRCULATION; WINTER AB The relationship between Northern Hemisphere (NH) tropospheric and stratospheric wave-like anomalies of spherical zonal wave number (ZWN) 1 is studied by applying Canonical Correlation Analysis (CCA). A lag-correlation technique is used with 10-day lowpass altered daily time series of 50- and 500-hPa geopotential heights. Generally stratospheric circulation is determined by ultralong tropospheric planetary waves. During winter seasons characterized either by an anomalously strong or weak polar winter vortex different propagation characteristics for waves of ZWN 1 are observed. The non-linear perspective of the results have implications for medium range weather forecast and climate sensitivity experiments. C1 NASA, Goddard Inst Space Studies, New York, NY 10025 USA. Max Planck Inst Meteorol, D-20146 Hamburg, Germany. Columbia Univ, Ctr Climate Syst Res, New York, NY USA. RP Perlwitz, J (reprint author), NASA, Goddard Inst Space Studies, 2880 Broadway, New York, NY 10025 USA. RI Perlwitz, Judith/B-7201-2008 OI Perlwitz, Judith/0000-0003-4061-2442 NR 16 TC 48 Z9 58 U1 1 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 JAN 15 PY 2001 VL 28 IS 2 BP 271 EP 274 DI 10.1029/2000GL012405 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 392MN UT WOS:000166415400019 ER PT J AU Kim, KM Lau, KM AF Kim, KM Lau, KM TI Dynamics of monsoon-induced biennial variability in ENSO SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NINO SOUTHERN-OSCILLATION; ASIAN SUMMER MONSOON; EL-NINO; INTERANNUAL VARIABILITY; CLIMATE SYSTEM; OCEAN; MODEL; PACIFIC; IMPACT; TIME AB The mechanism of the quasi-biennial tendency in ENSO-monsoon coupled system is investigated using an intermediate coupled model. The monsoon wind forcing is prescribed as a function of SST anomalies based on the relationship between zonal wind anomalies over the western Pacific to sea level change in the equatorial eastern Pacific. The key mechanism of quasi-biennial tendency in El Nino evolution is found to be in the strong coupling of ENSO to monsoon wind forcing over the western Pacific. Strong boreal summer monsoon wind forcing, which lags the maximum SST anomaly in the equatorial eastern Pacific approximately 6 months, tends to generate Kelvin waves of the opposite sign to anomalies in the eastern Pacific and initiates the turnabout in the eastern Pacific. Boreal winter monsoon forcing, which has zero lag with maximum SST in the equatorial eastern Pacific, tends to damp the ENSO oscillations. C1 NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Greenbelt, MD 20771 USA. RP Kim, KM (reprint author), NASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Code 913, Greenbelt, MD 20771 USA. RI Kim, Kyu-Myong/G-5398-2014 NR 29 TC 52 Z9 57 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 JAN 15 PY 2001 VL 28 IS 2 BP 315 EP 318 DI 10.1029/2000GL012465 PG 4 WC Geosciences, Multidisciplinary SC Geology GA 392MN UT WOS:000166415400030 ER PT J AU Thomas, AC Blanco, JL Carr, ME Strub, PT Osses, J AF Thomas, AC Blanco, JL Carr, ME Strub, PT Osses, J TI Satellite-measured chlorophyll and temperature variability off northern Chile during the 1996-1998 La Nina and El Nino SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID CALIFORNIA CURRENT; INTERANNUAL VARIABILITY; PIGMENT CONCENTRATIONS; PHYTOPLANKTON; PERU; CIRCULATION; COAST; ZONE AB Time series of satellite measurements are used to describe patterns of surface temperature and chlorophyll associated with the 1996 cold La Nina phase and the 1997-1998 warm El Nino phase of the El Nino - Southern Oscillation cycle in the upwelling region off northern Chile. Surface temperature data are available through the entire study period. Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data first became available in September 1997 during a relaxation in El Nino conditions identified by in situ hydrographic data. Over the time period of coincident satellite data, chlorophyll patterns closely track surface temperature patterns. Increases both in nearshore chlorophyll concentration and in cross-shelf extension of elevated concentrations are associated with decreased coastal temperatures during both the relaxation in El Nino conditions in September-November 1997 and the recovery from EI Nino conditions after March 1998. Between these two periods during austral summer (December 1997 to March 1998) and maximum El Nino temperature anomalies, temperature patterns normally associated with upwelling were absent and chlorophyll concentrations were minimal. Cross-shelf chlorophyll distributions appear to be modulated by surface temperature frontal zones and are positively correlated with a satellite-derived upwelling index. Frontal zone patterns and the upwelling index in 1996 imply an austral summer nearshore chlorophyll maximum, consistent with SeaWiFS data from I 1998-1999, after the El Nino. SeaWiFS retrievals in the data set used here are higher than in situ measurements by a factor of 2-4; however, consistency in the offset suggests relative patterns are valid. C1 Univ Maine, Sch Marine Sci, Orono, ME 04469 USA. Inst Formento Pesquero, Valparaiso, Chile. CALTECH, Jet Propuls Lab, Pasadena, CA 91009 USA. Oregon State Univ, Coll Ocean & Atmospher Sci, Corvallis, OR 97331 USA. RP Thomas, AC (reprint author), Univ Maine, Sch Marine Sci, Orono, ME 04469 USA. NR 31 TC 60 Z9 62 U1 1 U2 8 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 JAN 15 PY 2001 VL 106 IS C1 BP 899 EP 915 DI 10.1029/1999JC000052 PG 17 WC Oceanography SC Oceanography GA 393UM UT WOS:000166488100004 ER PT J AU Korotaev, GK Saenko, OA Koblinsky, CJ AF Korotaev, GK Saenko, OA Koblinsky, CJ TI Satellite altimetry observations of the Black Sea level SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID VARIABILITY; OCEAN; WIND AB The paper is devoted to the application of satellite altimetry from the TOPEX/ Poseidon and ERS-1 missions to the Black Sea. We use the NASA Ocean Altimeter Pathfinder Project colinear data set and monthly climatic hydrography to restore the dynamical sea level, that which connected with the Black Sea circulation. Two realizations are created from collinear and grid data sets. The Black Sea hydrographic survey data collected by the Cooperative Marine Science Programme for the Black Sea are used for validation of both products. The estimated rms accuracy of the Black Sea dynamical level is about 3 cm. The grid data product is used for the analysis of seasonal and mesoscale variability of the Black Sea level. The observations show that the Black Sea circulation has strong seasonal variation. It attenuates in summer to autumn and intensifies in winter to spring. This variability is accompanied by a western-phase propagation of the sea level. A simple two-layer model of the wind-induced circulation in the rectangular basin provides an interpretation of these results. It is shown that the seasonal variability of the geostrophic circulation is most likely produced by the annual changes of the wind stress curl. The western phase propagation is treated as the radiation of Rossby waves from the eastern coast of the basin. Typical periods of the mesoscale oscillations of the dynamical sea level are estimated from the TOPEX/Poseidon altimeter time series in different parts of the Black Sea by means of a spectral analysis. The strongest mesoscale oscillations have periods of about 120 days and are located in the southeastern part of the basin, where the Rim Current bifurcates, and off the Crimean peninsula, where the Rim Current meanders as a result of the local orography. C1 Ukrainian Acad Sci, Inst Marine Hydrophys, UA-335000 Sevastopol, Crimea, Ukraine. Univ Victoria, Sch Earth & Ocean Sci, Victoria, BC V8W 2YZ, Canada. NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Korotaev, GK (reprint author), Ukrainian Acad Sci, Inst Marine Hydrophys, UA-335000 Sevastopol, Crimea, Ukraine. NR 25 TC 33 Z9 35 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JAN 15 PY 2001 VL 106 IS C1 BP 917 EP 933 DI 10.1029/2000JC900120 PG 17 WC Oceanography SC Oceanography GA 393UM UT WOS:000166488100005 ER PT J AU Holt, B Martin, S AF Holt, B Martin, S TI The effect of a storm on the 1992 summer sea ice cover of the Beaufort, Chukchi, and East Siberian Seas SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SYNTHETIC-APERTURE-RADAR; IMAGERY; MELT AB For the summer Beaufort, Chukchi, and East Siberian Seas a variety of active and passive microwave satellite data are used to determine the response of the ice edge and interior to a storm. Specifically, the study concentrates on a low-pressure system that passed over the region between August 14 and 20, 1992, with peak geostrophic winds of about 18 m s(-1). Through the use of the ERS-1 imaging radar and the Special Sensor Microwave/Imager the ice response is examined at two locations: at the ice edge for a nearly stationary location in the Chukchi Sea and in the ice interior along three swaths in the Beaufort, Chukchi, and East Siberian Seas. The ice edge observations show that the storm fractures the large flees into small flees, some of which are advected into the adjacent warm water. The ice interior observations show that the storm caused an increase in the open water amount and a shift in the flee size distribution toward smaller floes. In the ice interior, application of the cumulative number distribution N(d), where N is the number of flees per unit area that are no smaller than some flee diameter d, shows that for d > 1 km, N behaves like d(-alpha), where cr lies in the range 1.8-2.9. Our analysis also shows that this slope is not affected by the storm and is slightly larger near the ice edge. C1 CALTECH, Jet Propuls Lab, Pasadena, CA 91109 USA. Univ Washington, Sch Oceanog, Seattle, WA 98195 USA. RP Holt, B (reprint author), CALTECH, Jet Propuls Lab, 4800 Oak Grove Dr,Mail Stop 300-323, Pasadena, CA 91109 USA. NR 22 TC 22 Z9 23 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JAN 15 PY 2001 VL 106 IS C1 BP 1017 EP 1032 DI 10.1029/1999JC000110 PG 16 WC Oceanography SC Oceanography GA 393UM UT WOS:000166488100012 ER PT J AU Devi, VM Benner, DC Smith, MAH Rinsland, CP AF Devi, VM Benner, DC Smith, MAH Rinsland, CP TI Measurements of air broadened width and air induced shift coefficients and line mixing in the nu(5) band of (CH3D)-C-12 SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE methane; monodeuterated methane; infrared spectra; Fourier transform infrared (FTIR) spectroscopy; spectral lineshape ID INFRARED SOLAR SPECTRA; 6-10 MU-M; FITTING TECHNIQUE; CH3D; ABSORPTION; CM(-1); REGION; INTENSITIES; (H2O)-O-16; DATABASE AB In this study we report the first experimental measurements of air-broadening and air-induced pressure-shift coefficients for approximately 400 transitions in the nu(5)(E) perpendicular band of (CH3D)-C-12 in the spectral region 1276-1600 cm(-1). These results were obtained from analysis of 11 room temperature laboratory absorption spectra recorded at 0.005 cm(-1) resolution with the McMath-Pierce Fourier transform spectrometer located on Kitt Peak National Solar Observatory. A multispectrum non-linear least-squares fitting algorithm was used in retrieving the results. The measured broadening coefficients vary from to 0.0265 to 0.0735 cm(-1) atm(-1) at 296 K for transitions up to J" = 17 and K" = 12, including 12 forbidden lines with Delta K = +/- 2 (5 (O)Q and 7 (S)Q). The corresponding pressure-induced shift coefficients range from + 0.0003 and - 0.0088 cm(-1) atm(-1) and the majority of these are negative. Subsets of air-broadened width coefficients vary somewhat smoothly as a function of the rotational quanta, and this behavior has been modeled to +/- 5% using empirical expressions. The off-diagonal relaxation matrix coefficients, W-ij, in cm(-1) atm(-1) at 296 K which are associated with line mixing were determined for a few transitions with K" = 3 (A(+)A(-) splitting) in the PP and PQ sub-bands. The broadening and pressure-shift coefficients obtained from the analysis are compared with values previously determined by us for similar transitions in the nu(6)(E) perpendicular band of (CH3D)-C-12 and with other values reported in the literature. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Coll William & Mary, Dept Phys, Williamsburg, VA 23187 USA. NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Devi, VM (reprint author), Coll William & Mary, Dept Phys, Box 8795, Williamsburg, VA 23187 USA. NR 22 TC 16 Z9 16 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 JAN 15 PY 2001 VL 68 IS 2 BP 135 EP 161 DI 10.1016/S0022-4073(00)00018-2 PG 27 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 364ZF UT WOS:000089923400002 ER PT J AU Ustinov, EA AF Ustinov, EA TI Adjoint sensitivity analysis of radiative transfer equation: temperature and gas mixing ratio weighting functions for remote sensing of scattering atmospheres in thermal IR SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article DE adjoint sensitivity analysis; radiative transfer; remote sensing ID PHASE FUNCTION; EXITING RADIANCES; RETRIEVAL AB Sensitivity analysis based on of the adjoint equation of radiative transfer is applied to the case of atmospheric remote sensing in the thermal spectral region with non-negligible atmospheric scattering. Analytic expressions for the weighting functions for retrievals of temperature and gas mixing ratio are derived. It is demonstrated that these expressions include the case of pure absorption as a particular case when single scattering albedo of atmospheric scattering can be neglected. (C) 2000 Published by Elsevier Science Ltd. C1 CALTECH, Jet Prop Lab, Div Earth & Space Sci, Pasadena, CA 91109 USA. RP Ustinov, EA (reprint author), CALTECH, Jet Prop Lab, Div Earth & Space Sci, Mail Stop 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA. RI Ustinov, Eugene/D-1350-2015 OI Ustinov, Eugene/0000-0003-0227-4286 NR 14 TC 23 Z9 23 U1 0 U2 3 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 JAN 15 PY 2001 VL 68 IS 2 BP 195 EP 211 DI 10.1016/S0022-4073(00)00022-4 PG 17 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 364ZF UT WOS:000089923400005 ER PT J AU Gillis, JR Goldman, A Stark, G Rinsland, CP AF Gillis, JR Goldman, A Stark, G Rinsland, CP TI Line parameters for the A(2)Sigma(+)-X-2 Pi bands of OH SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID ABSORPTION CROSS-SECTIONS; EMISSION RATE FACTORS; LONG-PATH ABSORPTION; TRANSITION-PROBABILITIES; ROTATIONAL LINES; MOLECULAR-CONSTANTS; TROPOSPHERIC OH; TERM VALUES; SPECTRA; STATES AB Updated line parameters, including line positions and intensities, have been generated for the six strongest A(2)Sigma(+)(v') - X(2)Pi(i)(v") bands of OH, i.e., v' - v" = 0, + 1, v" = 0, 1, 2, applicable to atmospheric and high temperatures. Results from recent laboratory measurements and theoretical studies have been incorporated into the calculations. Tables of line parameters are available for 296 and 4600 K. (C) 2000 Elsevier Science Ltd. All rights reserved. C1 Univ Denver, Dept Phys & Astron, Denver, CO 80208 USA. Boeing Space & Commun Grp, Seattle, WA 98124 USA. Wellesley Coll, Dept Phys, Wellesley, MA 02481 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 40 TC 28 Z9 28 U1 1 U2 15 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 JAN 15 PY 2001 VL 68 IS 2 BP 225 EP 230 DI 10.1016/S0022-4073(00)00011-X PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA 364ZF UT WOS:000089923400007 ER PT J AU Kouatchou, J AF Kouatchou, J TI Parallel implementation of a high-order implicit collocation method for the heat equation SO MATHEMATICS AND COMPUTERS IN SIMULATION LA English DT Article DE implicit collocation methods; high-order compact scheme; matrix inverse; iterative methods; parallel computers AB We combine a high-order compact finite difference approximation and collocation techniques to numerically solve the two-dimensional heat equation. The resulting method is implicit and can be parallelized with a strategy that allows parallelization across both time and space. We compare the parallel implementation of the new method with a classical implicit method, namely the Crank-Nicolson method, where the parallelization is done across space only. We find the set of conditions for which each method is more advantageous than the other. Numerical experiments are carried out on the SGI Origin 2000. (C) 2001 IMACS. Published by Elsevier Science B.V. All rights reserved. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Morgan State Univ, Baltimore, MD 21239 USA. RP Kouatchou, J (reprint author), NASA, Goddard Space Flight Ctr, Code 931, Greenbelt, MD 20771 USA. RI Koutachou, Jules/D-4773-2016 OI Koutachou, Jules/0000-0002-5525-9875 NR 9 TC 8 Z9 8 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 JAN 15 PY 2001 VL 54 IS 6 BP 509 EP 519 DI 10.1016/S0378-4754(00)00280-9 PG 11 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA 395GC UT WOS:000166571300006 ER PT J AU Tinto, M Armstrong, JW Estabrook, FB AF Tinto, M Armstrong, JW Estabrook, FB TI Discriminating a gravitational wave background from instrumental noise in the LISA detector SO PHYSICAL REVIEW D LA English DT Article ID RADIATION AB The multiple Doppler readouts available with the Laser Interferometer Space Antenna (LISA) permit simultaneous formation of several observables. All are independent of laser phase fluctuations, but have different couplings to gravitational waves and the various LISA instrumental noises. Comparison, for example, of the Michelson interferometer observable with the fully symmetric Sagnac data-type allows discrimination between a confusion-limited gravitational wave background and instrumental noise. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Tinto, M (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM massimo.tinto@jpl.nasa.gov; john.w.armstrong@jpl.nasa.gov; frank.b.estabrook@jpl.nasa.gov NR 8 TC 45 Z9 45 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD JAN 15 PY 2001 VL 63 IS 2 AR 021101 PG 3 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA 394JK UT WOS:000166520100001 ER PT J AU Kaplinghat, M Turner, MS AF Kaplinghat, M Turner, MS TI Precision cosmology and the density of baryons in the universe SO PHYSICAL REVIEW LETTERS LA English DT Article ID BIG-BANG NUCLEOSYNTHESIS AB Big-bang nucleosynthesis (BBN) and cosmic microwave background (CMB) anisotropy measurements give independent, accurate measurements of the baryon density and can test the framework of the standard cosmology. Early CMB data are consistent with the long-standing conclusion from BBN that baryons constitute a small fraction of matter in the Universe, but may indicate a slightly higher value for the baryon density. We clarify precisely what the two methods determine and point out that differing values for the baryon density can indicate either an inconsistency or physics beyond the standard models of cosmology and particle physics. We discuss other signatures of the new physics in CMB anisotropy. C1 Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Univ Chicago, Dept Phys, Enrico Fermi Inst, Chicago, IL 60637 USA. RP Kaplinghat, M (reprint author), Univ Chicago, Dept Astron & Astrophys, 5640 S Ellis Ave, Chicago, IL 60637 USA. NR 29 TC 29 Z9 29 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 JAN 15 PY 2001 VL 86 IS 3 BP 385 EP 388 DI 10.1103/PhysRevLett.86.385 PG 4 WC Physics, Multidisciplinary SC Physics GA 392GB UT WOS:000166402400005 PM 11177837 ER PT J AU Roth, M Cowan, TE Key, MH Hatchett, SP Brown, C Fountain, W Johnson, J Pennington, DM Snavely, RA Wilks, SC Yasuike, K Ruhl, H Pegoraro, F Bulanov, SV Campbell, EM Perry, MD Powell, H AF Roth, M Cowan, TE Key, MH Hatchett, SP Brown, C Fountain, W Johnson, J Pennington, DM Snavely, RA Wilks, SC Yasuike, K Ruhl, H Pegoraro, F Bulanov, SV Campbell, EM Perry, MD Powell, H TI Fast ignition by intense laser-accelerated proton beams SO PHYSICAL REVIEW LETTERS LA English DT Article ID FUSION; FUEL AB The concept of fast ignition with inertial confinement fusion (ICF) is a way to reduce the energy required for ignition and burn and to maximize the gain produced by a single implosion. Based on recent experimental findings at the PETAWATT laser at Lawrence Livermore National Laboratory, an intense proton beam to achieve fast ignition is proposed. It is produced by direct laser acceleration and focused onto the pellet from the rear side of an irradiated target and can be integrated into a hohlraum for indirect drive ICF. C1 Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. Gesellsch Schwerionenforsch, Darmstadt, Germany. Gen Atom Co, San Diego, CA 92186 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. Osaka Univ, ILE, Suita, Osaka 565, Japan. Max Born Inst, Berlin, Germany. Ist Nazl Fis Mat, Sez A, Pisa, Italy. RAS, Inst Gen Phys, Moscow 117901, Russia. RP Roth, M (reprint author), Univ Calif Lawrence Livermore Natl Lab, Livermore, CA 94550 USA. RI Bulanov, Sergei/A-1721-2013; Cowan, Thomas/A-8713-2011; OI Cowan, Thomas/0000-0002-5845-000X; Pegoraro, Francesco/0000-0002-7216-5491 NR 16 TC 785 Z9 821 U1 14 U2 75 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 JAN 15 PY 2001 VL 86 IS 3 BP 436 EP 439 DI 10.1103/PhysRevLett.86.436 PG 4 WC Physics, Multidisciplinary SC Physics GA 392GB UT WOS:000166402400017 PM 11177849 ER PT J AU Slysh, VI Voronkov, MA Migenes, V Shibata, KM Umemoto, T Altunin, VI Val'tts, IE Kanevsky, BZ Popov, MV Kovalenko, AV Fomalont, EB Poperechenko, BA Gorshenkov, YN Carlson, BR Dougherty, SM Reynolds, JE Jiang, DR Smirnov, AI Grachev, VG AF Slysh, VI Voronkov, MA Migenes, V Shibata, KM Umemoto, T Altunin, VI Val'tts, IE Kanevsky, BZ Popov, MV Kovalenko, AV Fomalont, EB Poperechenko, BA Gorshenkov, YN Carlson, BR Dougherty, SM Reynolds, JE Jiang, DR Smirnov, AI Grachev, VG TI Space-VLBI observations of the OH maser OH 34.26+0.15: low interstellar scattering SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE masers; scattering; stars : formation; HII regions; ISM : molecules ID H-II-REGION; VLA AB We report on the first space-VLBI observations of the OH 34.26+0.15 maser in two main-line OH transitions at 1665 and 1667 MHz. The observations involved the space radio telescope on board the Japanese satellite HALCA and an array of ground radio telescopes. The map of the maser region and images of individual maser spots were produced with an angular resolution of 1 mas, which is several times higher than the angular resolution available on the ground. The maser spots were only partly resolved and a lower limit to the brightness temperature 6 x 10(12) K was obtained. The maser seems to be located in the direction of low interstellar scattering, an order of magnitude lower than the scattering of a nearby extragalactic source and pulsar. C1 PN Lebedev Phys Inst, Ctr Astro Space, Moscow 117810, Russia. Univ Guanajuato, Dept Astron, Guanajuato 36000, Mexico. Natl Astron Observ, Tokyo 181, Japan. CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. Moscow Power Engn Inst, Special Res Bur, Moscow 111250, Russia. Natl Res Council Canada, Herzberg Inst Astrophys, Domin Radio Astrophys Observ, Penticton, BC V2A 6K3, Canada. Australia Telescope Natl Facil, Epping, NSW 2121, Australia. Shanghai Astron Observ, Shanghai 200080, Peoples R China. Inst Appl Astron, St Petersburg 197042, Russia. RP Slysh, VI (reprint author), PN Lebedev Phys Inst, Ctr Astro Space, Profsoyuznaya 84-32, Moscow 117810, Russia. RI Migenes, Victor/F-3157-2015; Popov, Mikhail/M-6118-2015; Valtts, Irina/M-6869-2015; Kovalenko, Anatoly/N-1591-2015; Kanevsky, Boris/M-4137-2015 OI Migenes, Victor/0000-0002-7990-2191; Valtts, Irina/0000-0003-4032-5590; Kanevsky, Boris/0000-0002-1697-7508 NR 19 TC 16 Z9 16 U1 1 U2 1 PU BLACKWELL SCIENCE LTD PI OXFORD PA P O BOX 88, OSNEY MEAD, OXFORD OX2 0NE, OXON, ENGLAND SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JAN 11 PY 2001 VL 320 IS 2 BP 217 EP 223 DI 10.1046/j.1365-8711.2001.03959.x PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 395HJ UT WOS:000166574700003 ER PT J AU Buckley, DAH Coe, MJ Stevens, JB van der Heyden, K Angelini, L White, N Giommi, P AF Buckley, DAH Coe, MJ Stevens, JB van der Heyden, K Angelini, L White, N Giommi, P TI Multiwaveband studies of the hard ROSAT SMC transient 1WGA J0053.8-7226: a new X-ray pulsar SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE binaries : general; stars : emission-line, Be; pulsars : general; infrared : stars; X-rays : stars ID SMALL-MAGELLANIC-CLOUD; OPTICAL COUNTERPARTS AB We report on two optical candidates for the counterpart to an X-ray source in the Small Magellanic Cloud, 1WGA J0053.8-7226, identified as a serendipitous X-ray source from the ROSAT Position Sensitive Proportional Counter (PSPC) archive, and also observed by the Einstein Imaging Proportional Counter. Its X-ray properties, namely the hard X-ray spectrum, flux variability and column density, indicate a hard, transient source, with a luminosity of similar to3.8 x 10(35) erg s(-1). XTE and ASCA observations have confirmed the source to be an X-ray pulsar, with a 46-s spin period. Our optical observations reveal two possible candidates within the error circle. Both exhibit strong H alpha and weaker H beta emission. The optical colours indicate that both objects are Be-type stars. The Be nature of the stars implies that the counterpart is most likely a Be/X-ray binary system. Subsequent infrared (IR) photometry (JHK) of one of the objects shows that the source varies by at least 0.5 mag, while the (J - K) measured nearly simultaneously with the UBVRI and spectroscopic observations indicate an IR excess of similar to0.3 mag. C1 S African Astron Observ, ZA-7935 Cape Town, South Africa. Univ Southampton, Dept Phys & Astron, Southampton SO17 3BJ, Hants, England. NASA, HEASARC, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Buckley, DAH (reprint author), S African Astron Observ, POB 9, ZA-7935 Cape Town, South Africa. RI White, Nicholas/B-6428-2012; OI White, Nicholas/0000-0003-3853-3462; giommi, paolo/0000-0002-2265-5003 NR 26 TC 14 Z9 14 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 JAN 11 PY 2001 VL 320 IS 2 BP 281 EP 288 DI 10.1046/j.1365-8711.2001.03982.x PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 395HJ UT WOS:000166574700009 ER PT J AU Scoccimarro, RN Feldman, HA Fry, JN Frieman, JA AF Scoccimarro, RN Feldman, HA Fry, JN Frieman, JA TI The bispectrum of IRAS redshift catalogs SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; large-scale structure of universe; methods : statistical ID 3-POINT CORRELATION-FUNCTION; POWER-SPECTRUM ANALYSIS; DARK-MATTER COSMOGONY; LARGE-SCALE STRUCTURE; GRAVITATIONAL-INSTABILITY; LAGRANGIAN APPROACH; SKEWNESS; SPACE; BIAS; DISTORTIONS AB We compute the bispectrum for the galaxy distribution in the IRAS QDOT, 2 Jy, and 1.2 Jy redshift catalogs for wavenumbers 0.05 less than or equal to k less than or equal to 0.2 h Mpc(-1) and compare the results with predictions from gravitational instability in perturbation theory. Taking into account redshift-space distortions, nonlinear evolution, the survey selection function, and discreteness and finite-volume effects, all three catalogs show evidence for the dependence of the bispectrum on the configuration shape predicted by gravitational instability. Assuming Gaussian initial conditions and local biasing parameterized by linear and nonlinear bias parameters b(1) and b(2), a likelihood analysis yields 1/b(1) = 1.32(-0.58)(+0.36), 1.15(-0.39)(+0.39) and b(2)/b(1)(2) = -0.57-(+0.45)(0.30), -0.50(-0.51)(+0.31) for the 2 and 1.2 Jy samples, respectively. This implies that IRAS galaxies trace dark matter increasingly weakly as the density contrast increases, consistent with their being under-represented in clusters. In a model with chi (2) non-Gausian initial conditions, the bispectrum displays an amplitude and scale dependence different from that found in the Gaussian case; if IRAS galaxies do not have bias b(1) >1 at large scales, chi (2) non-Gaussian initial conditions are ruled out at the 95% confidence level. The IRAS data do not distinguish between Lagrangian and Eulerian local bias. C1 CITA, McLennan Phys Labs, Toronto, ON M5S 3H8, Canada. Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA. Univ Florida, Dept Phys, Gainesville, FL 32611 USA. NASA, Fermilab Astrophys Ctr, Fermi Natl Accelerator Lab, Batavia, IL 60510 USA. Univ Chicago, Dept Astron & Astrophys, Chicago, IL 60637 USA. RP Inst Adv Study, Sch Nat Sci, Einstein Dr, Princeton, NJ 08540 USA. EM scoccima@ias.edu; feldman@ukans.edu; fry@ufl.edu; frieman@fnal.gov NR 44 TC 85 Z9 87 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 JAN 10 PY 2001 VL 546 IS 2 BP 652 EP 664 DI 10.1086/318284 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393GH UT WOS:000166460500004 ER PT J AU Vreeswijk, PM Fruchter, A Kaper, L Rol, E Galama, TJ van Paradijs, J Kouveliotou, C Wijers, RAMJ Pian, E Palazzi, E Masetti, N Frontera, F Savaglio, S Reinsch, K Hessman, FV Beuermann, K Nicklas, H van den Heuvel, EPJ AF Vreeswijk, PM Fruchter, A Kaper, L Rol, E Galama, TJ van Paradijs, J Kouveliotou, C Wijers, RAMJ Pian, E Palazzi, E Masetti, N Frontera, F Savaglio, S Reinsch, K Hessman, FV Beuermann, K Nicklas, H van den Heuvel, EPJ TI VLT spectroscopy of GRB 990510 and GRB 990712: Probing the faint and bright ends of the gamma-ray burst host galaxy population SO ASTROPHYSICAL JOURNAL LA English DT Article DE cosmology : observations; galaxies : distances and redshifts; galaxies : starburst; gamma rays : bursts ID EMISSION-LINE SPECTRA; STAR-FORMATION RATE; 28 FEBRUARY 1997; FIELD GALAXIES; ERROR BOX; GRB-990510; ABUNDANCES; AFTERGLOW; REDSHIFT; ENVIRONMENT AB We present time-resolved optical spectroscopy of the afterglows of the gamma-ray bursts GRB 990510 and GRB 990712. Through the identification of several absorption lines in the first-epoch GRB 990510 spectrum, we determine the redshift for this burst at z greater than or equal to 1.619. No clear emission lines are detected. The strength of the Mg I feature is indicative of a dense environment, most likely the host galaxy of GRB 990510. Although the host is extremely faint the GRB afterglow allows us to probe its inter-stellar medium and-in principle-to measure its metallicity. The optical spectrum of GRB 990712 (whose host galaxy is the brightest of the known GRB hosts at cosmological redshifts) shows clear features both in emission and absorption, at a redshift of z = 0.4331 +/- 0.0004. On the basis of several line emission diagnostic diagrams, we conclude that the host galaxy of GRB 990712 is most likely an H II galaxy. We derive an unreddened [O II] star formation rate of 2.7 +/- 0.8 M-. yr(-1). Correcting for the measured extinction intrinsic to the host galaxy (A(v) = 3.4(-1.7)(+2.4)), this value increases to 35(-25)(+178) M-. yr(-1). The [O II] equivalent width, compared to that of field galaxies at z less than or equal to1, also suggests that the host of GRB 990712 is vigorously forming stars. We employ the oxygen and H beta emission-line intensities to estimate the global oxygen abundance for the host of GRB 990712: log (O/H) = 3.7 +/- 0.4, which is slightly below the lowest metallicity one finds in nearby spiral galaxies. For both GRBs we study the time evolution of the adsorption lines, whose equivalent width might be expected to change with time if the burst resides in a dense compact medium. We find no evidence for a significant change in the Mg II width. C1 Univ Amsterdam, Astron Inst Anton Pannekoek, NL-1098 SJ Amsterdam, Netherlands. Natl Inst Nucl & High Energy Phys, Ctr High Energy Astrophys, NL-1098 SJ Amsterdam, Netherlands. Space Telescope Sci Inst, Baltimore, MD 21218 USA. CALTECH, Pasadena, CA 91125 USA. Univ Alabama, Dept Phys, Huntsville, AL 35899 USA. Univ Space Res Assoc, Columbia, MD 21044 USA. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA. CNR, ITESRE, I-40129 Bologna, Italy. Univ Ferrara, Dept Phys, I-44100 Ferrara, Italy. Univ Sternwarte, D-37083 Gottingen, Germany. RP Vreeswijk, PM (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 58 TC 102 Z9 102 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 JAN 10 PY 2001 VL 546 IS 2 BP 672 EP 680 DI 10.1086/318308 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393GH UT WOS:000166460500006 ER PT J AU Yaqoob, T George, IM Nandra, K Turner, TJ Serlemitsos, PJ Mushotzky, RF AF Yaqoob, T George, IM Nandra, K Turner, TJ Serlemitsos, PJ Mushotzky, RF TI Physical diagnostics from a narrow FeK alpha emission line detected by Chandra in the Seyfert 1 galaxy NGC 5548 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 5548); galaxies : Seyfert; quasars : emission lines; X-rays : galaxies ID ACTIVE GALACTIC NUCLEI; X-RAY-FLUORESCENCE; IRON K-LINE; MCG-6-30-15; VARIABILITY; NGC-5548; REGION AB We report the detection of a narrow Fe K alpha emission line in the Seyfert 1 galaxy NGC 5548 with the Chandra High-Energy Transmission Grating. In the galaxy frame we measure a center energy of 6.402(-0.025)(+0.027) keV, a FWHM of 4515(-2645)(+3525) km s(-1), an intensity of 3.6(-1.5)(+1.7) x 10(-5) photons cm(-2) s(-1), with an equivalent width of 133(-54)(+62) eV (errors are 90% confidence for one parameter). The line is only marginal resolved at the 90% confidence level. The line energy is consistent with an origin in cold, neutral matter, but ionization states up to similar to Fe XVIII are not ruled out. We cannot constrain the detailed dynamics but, assuming Keplerian motion, the velocity width is consistent with the line being produced in the outer optical/UV broad-line region (BLR) at about a light month from the central X-ray source. We cannot rule out some contribution to the narrow Fe K alpha line from a putative, parsec-scale, obscuring torus that is postulated to be a key component of active galactic nuclei (AGNs) unification models. The continuum intensity during the Chandra observation was a factor similar to2 less than typical historical levels. If the X-ray continuum was at least a factor of 2 higher in the recent past before the Chandra observation and the narrow Fe K alpha intensity had not yet responded to such a change, then the predicted line intensity and equivalent width for an origin in the BLR is within the 90% measurement errors. Anisotropic X-ray continuum illumination of the BLR and/or additional line emission from a torus structure would improve the agreement with observation. Two out of three archival ASCA data sets are consistent with the narrow line being present with the same intensity as in the Chandra observation. However, there is strong evidence that the narrow-line intensity varied and was unusually low during one of the ASCA campaigns. In general, inclusion of the narrow line to model the overall broad Fe K alpha line profile in terms of a rotating disk plus black-hole model can have a non-negligible effect on the disk line intensity and variability properties. Variability of the broad disk line in NGC 5548 is difficult to reconcile with the expectations of the simple disk model, even when the narrow-line component is accounted for. It will be critical to ascertain the importance of a similar nondisk Fe K alpha line in other Seyfert 1 galaxies. Future monitoring of the narrow Fe K alpha component with large collecting area and high spectral resolution will enable reverberation mapping the BLR region, complementary to similar studies using the optical/UV lines, and therefore provide independent constraints on the black-hole mass. C1 NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Maryland Baltimore Cty, Dept Phys, Joint Ctr Astrophys, Baltimore, MD 21250 USA. Univ Space Res Assoc, Columbia, MD USA. RP Yaqoob, T (reprint author), NASA, High Energy Astrophys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NR 43 TC 132 Z9 133 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 JAN 10 PY 2001 VL 546 IS 2 BP 759 EP 768 DI 10.1086/318315 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393GH UT WOS:000166460500012 ER PT J AU Smith, AM Collins, NR Waller, WH Roberts, MS Smith, DA Bohlin, RC Cheng, KP Fanelli, MN Neff, SG O'Connell, RW Parise, RA Smith, EP Stecher, TP AF Smith, AM Collins, NR Waller, WH Roberts, MS Smith, DA Bohlin, RC Cheng, KP Fanelli, MN Neff, SG O'Connell, RW Parise, RA Smith, EP Stecher, TP TI Far-ultraviolet imagery of the edge-on spiral galaxy NGC 4631 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : individual (NGC 4631); galaxies : ISM; galaxies : kinematics and dynamics; galaxies : starburst; galaxies : star clusters; ultraviolet : galaxies ID STAR-FORMATION; ENERGY-DISTRIBUTIONS; IMAGING TELESCOPE; H-I; NGC-4631; STARBURST; CATALOG; SUPERSHELLS; EXTINCTION; PHOTOMETRY AB Far-ultraviolet (FUV) imagery of the edge-on, Sc/SBd galaxy NGC 4631 reveals very strong FUV emission, resulting from active star formation, uniformly distributed along the galactic midplane. Multiband imagery, H I and H II position-velocity curves, and extinction considerations all imply that the emission is from the outer edges of the visible galaxy. The overall FUV morphology of this edge-on disk system is remarkably similar to those of the "chain galaxies" evident at high redshift, thus suggesting a similar interpretation for at least some of those distant objects. FUV, U, B, and V magnitudes, measured for 48 star-forming regions, along with corresponding H alpha and H beta measurements are used to construct diagnostic color-color diagrams. Although there are significant exceptions, most of the star-forming regions are less massive and older than 30 Doradus. Comparison with the expectations from two star formation models yields ages of 2.7 to 10 Myr for the instantaneous burst (IB) model and star formation cutoff ages of 0 to 9 Myr for the continuous star formation (CSF) model. Interpreted in terms of the IB model the photometry implies a total created mass in the 48 star-forming regions of 2.5 x 10(7) M-.. When viewed as resulting from constant star formation the photometry implies a star formation rate of 0.33 M-. yr(-1). These results are compared to those derived from FIR and radio observations. Corrections for FUV emission reprocessed by interstellar grains are estimated. A large ring, similar to3 kpc in diameter, of 14 star-forming regions is concentrically located with an expanding H I shell toward the eastern end of the galaxy. Our observations imply that the shell may have been generated primarily by supernovae arising from 5.3]10(4) OB stars in a massive star-forming region beginning about 20 Myr ago, and that the presently observed FUV bright emission is due to second generation stars. C1 NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Raytheon STX Corp, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Tufts Univ, Medford, MA 02155 USA. Natl Radio Astron Observ, Charlottesville, VA 22903 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Calif State Univ Fullerton, Dept Phys, Fullerton, CA 92634 USA. Univ N Texas, Dept Phys, Denton, TX 76203 USA. Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA. NASA, Comp Sci Corp, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Smith, AM (reprint author), NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Code 681, Greenbelt, MD 20771 USA. NR 53 TC 12 Z9 12 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 JAN 10 PY 2001 VL 546 IS 2 BP 829 EP 844 DI 10.1086/318273 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393GH UT WOS:000166460500020 ER PT J AU Bruhweiler, FC Miskey, CL Smith, AM Landsman, W Malumuth, E AF Bruhweiler, FC Miskey, CL Smith, AM Landsman, W Malumuth, E TI Ionization, extinction, and spiral structure in the inner disk of NGC 1068 SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : individual (NGC 1068); galaxies : Seyfert ID NARROW-LINE REGION; IUE OBSERVATIONS; NGC-1068; GAS; NUCLEUS; BAR; EMISSION; LOCATION; DUST C1 Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. NASA, Raytheon ITSS, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Bruhweiler, FC (reprint author), Catholic Univ Amer, Dept Phys, Inst Astrophys & Computat Sci, Washington, DC 20064 USA. NR 28 TC 15 Z9 15 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JAN 10 PY 2001 VL 546 IS 2 BP 866 EP 876 DI 10.1086/318302 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393GH UT WOS:000166460500022 ER PT J AU Miller, JM Fox, DW Di Matteo, T Wijnands, R Belloni, T Pooley, D Kouveliotou, C Lewin, WHG AF Miller, JM Fox, DW Di Matteo, T Wijnands, R Belloni, T Pooley, D Kouveliotou, C Lewin, WHG TI Relativistic iron emission and disk reflection in galactic microquasar XTE J1748-288 SO ASTROPHYSICAL JOURNAL LA English DT Article DE black hole physics; line : profiles; relativity; X-rays : bursts; X-rays : stars ID RAY TIMING EXPLORER; BLACK-HOLE; SPECTRAL EVOLUTION; CYGNUS X-1; QUIESCENCE; LINE; MCG-6-30-15; OUTBURST; GALAXY; STATE AB We report evidence for an Fe K alpha fluorescence line feature and disk reflection in the very high, high-, and low-state X-ray spectra of the Galactic microquasar XTE J1748-288 during its 1998 June outburst. Spectral analyses are made on data gathered throughout the outburst by the Rossi X-Ray Timing Explorer Proportional Counter Array. Gaussian line, relativistic disk emission line, and ionized disk reflection models are fitted to the data. In the very high state the line profile appears strongly redshifted, consistent with disk emission from the innermost stable orbits around a maximally rotating Kerr black hole. In the high state the line profile is less redshifted and increasingly prominent. The low-state line profile is very strong (similar to0.5 keV equivalent width) and centered at 6.7 +/- 0.10 keV; disk line emission model fits indicate that the inner edge of the disk fluctuates between similar to 20Rg and similar to 100Rg in this state. The disk reflection fraction is traced through the outburst; reflection from an ionized disk is preferred in the very high and high states, and reflection from a relatively neutral disk is preferred in the low state. We discuss the implications of our findings for the binary system dynamics and accretion flow geometry in XTE J1748-288. C1 MIT, Dept Phys, Space Res Ctr, Cambridge, MA 02139 USA. Harvard Univ, Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA. Osservatorio Astron Brera, I-20121 Milan, Italy. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. RP Miller, JM (reprint author), MIT, Dept Phys, Space Res Ctr, Cambridge, MA 02139 USA. NR 53 TC 35 Z9 35 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 JAN 10 PY 2001 VL 546 IS 2 BP 1055 EP 1067 DI 10.1086/318291 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393GH UT WOS:000166460500037 ER PT J AU Wiedemann, G Deming, D Bjoraker, G AF Wiedemann, G Deming, D Bjoraker, G TI A sensitive search for methane in the infrared spectrum of tau Bootis SO ASTROPHYSICAL JOURNAL LA English DT Article DE binaries : general; infrared : stars; planetary systems; stars : individual (HR 5185) ID ECHELLE SPECTROGRAPH; BINARY-SYSTEMS; GIANT PLANETS; GLIESE 229B; CHEMISTRY; STARS AB We have searched for a methane signature in the infrared spectrum of tau Bootis, produced by the planetary companion. The observations comprise 598 low-noise (signal-to-noise ratio similar to 100), high-resolution (lambda/delta lambda = 4 x 10(4)) spectra near 3044 cm(-1), which we analyze by cross-correlating with a modeled planetary spectrum based on the work of Burrows & Sharp and Sudarsky, Burrows, & Pinto. The 3 sigma random noise level of our analysis is similar to 5 x 10(-5) stellar continuum flux units, and the confusion noise limit-measuring the resemblance of a cross-correlation feature to the spectrum of methane-is similar to 2.5 x 10(-4). We find a significant cross-correlation amplitude of similar to 3.3 x 10(-4) continuum units at a velocity near that of the star. This is likely due to methane from a low-mass companion in a long-period orbit. Fischer, Butler, & Marcy report a long-term velocity drift indicative of such a companion. But the system is known to be a visual binary with an eccentric orbit and is rapidly approaching periastron. Whether the visual companion can account for our observations and the Fischer et al. velocity drift depends on knowing the orbit more precisely. The stability of planetary orbits in this system also depends crucially on the properties of the binary orbit. A second cross-correlation feature, weaker and much more diffuse, has intensity amplitude similar to 2 x 10(-4) continuum units and occurs at a velocity amplitude of 71(+/-10) km s(-1), in agreement with the orbit claimed for the planet by Cameron et al. Like the first feature, it has passed several tests designed to reject systematic errors. We discuss the possibility that this second feature is due to the planet. C1 European So Observ, Munich, Germany. NASA, Goddard Space Flight Ctr, Planetary Syst Branch, Greenbelt, MD 20771 USA. RP European So Observ, Karl Schwarzschild Str 2, Munich, Germany. RI Bjoraker, Gordon/D-5032-2012 NR 32 TC 32 Z9 32 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 JAN 10 PY 2001 VL 546 IS 2 BP 1068 EP 1074 DI 10.1086/318316 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393GH UT WOS:000166460500038 ER PT J AU Mumma, MJ McLean, IS DiSanti, MA Larkin, JE Dello Russo, N Magee-Sauer, K Becklin, EE Bida, T Chaffee, F Conrad, AR Figer, DF Gilbert, AM Graham, JR Levenson, NA Novak, RE Reuter, DC Teplitz, HI Wilcox, MK Xu, LH AF Mumma, MJ McLean, IS DiSanti, MA Larkin, JE Dello Russo, N Magee-Sauer, K Becklin, EE Bida, T Chaffee, F Conrad, AR Figer, DF Gilbert, AM Graham, JR Levenson, NA Novak, RE Reuter, DC Teplitz, HI Wilcox, MK Xu, LH TI A survey of organic volatile species in comet C/1999 H1 (Lee) using NIRSPEC at the Keck Observatory SO ASTROPHYSICAL JOURNAL LA English DT Article DE comets : general; comets : individual (Lee (C/1999 H1)); infrared : solar system; solar system : formation ID DENSE INTERSTELLAR CLOUDS; EMISSION FEATURE; HYDROGEN-SULFIDE; CARBON-MONOXIDE; CHEMICAL-MODELS; P/SWIFT-TUTTLE; B2 HYAKUTAKE; HALE-BOPP; MU-M; METHANOL AB The organic volatile composition of the long-period comet C/1999 H1 (Lee) was investigated using the first of a new generation of cross-dispersed cryogenic infrared spectrometers (NIRSPEC, at the Keck Observatory atop Mauna Kea, HI). On 1999 August 19-21 the organics spectral region (2.9-3.7 mum) was completely sampled at both moderate and high dispersion, along with the CO fundamental region (near 4.67 mum), revealing emission from water, carbon monoxide, methanol, methane, ethane, acetylene, and hydrogen cyanide. Many new multiplets from OH in the 1-0 band were seen in prompt emission, and numerous new spectral lines were detected. Several spectral extracts are shown, and global production rates are presented for seven parent volatiles. Carbon monoxide is strongly depleted in comet Lee relative to comets Hyakutake and Hale-Bopp, demonstrating that chemical diversity occurred in the giant-planets' nebular region. C1 NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ Calif Los Angeles, Dept Phys & Astron, Los Angeles, CA 90095 USA. Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA. Rowan Univ, Dept Chem & Phys, Glassboro, NJ 08028 USA. Calif Assoc Res Astron, WM Keck Observ, Kamuela, HI 96743 USA. Space Telescope Sci Inst, Baltimore, MD 21218 USA. Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA. Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA. Iona Coll, Dept Phys, New Rochelle, NY 10801 USA. NASA, Astron & Solar Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. Univ New Brunswick, Dept Phys Sci, St John, NB E2L 4L5, Canada. RP Mumma, MJ (reprint author), NASA, Extraterr Phys Lab, Goddard Space Flight Ctr, Code 690, Greenbelt, MD 20771 USA. RI mumma, michael/I-2764-2013; Xu, Li-Hong/J-5095-2015; Magee-Sauer, Karen/K-6061-2015; Dello Russo, Neil/G-2727-2015 OI Magee-Sauer, Karen/0000-0002-4979-9875; Dello Russo, Neil/0000-0002-8379-7304 NR 60 TC 84 Z9 84 U1 0 U2 6 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 JAN 10 PY 2001 VL 546 IS 2 BP 1183 EP 1193 DI 10.1086/318314 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393GH UT WOS:000166460500051 ER PT J AU Kim, C Boller, T Ghosh, KK Swartz, DA Ramsey, BD AF Kim, C Boller, T Ghosh, KK Swartz, DA Ramsey, BD TI Detection of X-ray emission from galaxies inside the Bootes void SO ASTROPHYSICAL JOURNAL LA English DT Article DE galaxies : active; galaxies : Seyfert; galaxies : statistics; galaxies : structure; X-rays : galaxies ID NORTHERN SKY SURVEY; IRAS GALAXIES; ACTIVE GALAXIES; LINE GALAXIES; DIRECTION; REGION; VARIABILITY; CONNECTION; MORPHOLOGY; EVOLUTION AB We report the X-ray properties of Bootes void galaxies detected by the ROSAT All-Sky Survey (RASS). By searching the fields of 26 radio and 27 emission-line-selected void galaxies, we have detected nine X-ray-emitting void galaxies at greater than 2.7 sigma confidence level. Five of these nine galaxies are in the IRAS subsample. Two of the IRAS galaxies were previously identified in positional cross-correlation studies of the RASS and IRAS Point Source Catalogue sources. Three of the X-ray-emitting galaxies are active galactic nuclei (AGNs; IRAS 14288+5255, Mrk 845, and IRAS 15195+5050), three are emission-line galaxies (PC 1357+4641, CG 547, and CG 922), and the remaining three are of unknown spectral type (IRAS 14500+4804, CG 637, and IRAS 15092+3940). The far-infrared flux levels of the AGN sources imply that most of the observed X-ray emissivity is from starburst activity. We have carried out timing and spectral analysis for the Seyfert 1 galaxy Mrk 845. Poor statistics prevents detailed analysis of the remaining sources. Only two galaxies in our sample, BHI 1514+3819 and FSS 1515+3823, were observed during ROSAT pointed observations resulting in a nondetection at the 1 sigma level. C1 Chonbuk Natl Univ, Dept Earth Sci Educ, Chonju 561756, South Korea. Max Planck Inst Extraterr Phys, D-85748 Garching, Germany. NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Univ Space Res Assoc, Huntsville, AL 35812 USA. NASA, George C Marshall Space Flight Ctr, Dept Space Sci, Huntsville, AL 35812 USA. RP Kim, C (reprint author), Chonbuk Natl Univ, Dept Earth Sci Educ, Chonju 561756, South Korea. NR 38 TC 1 Z9 1 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 JAN 10 PY 2001 VL 546 IS 2 BP L91 EP L95 DI 10.1086/318868 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA 393GP UT WOS:000166461100004 ER PT J AU Wundrow, DW Goldstein, ME AF Wundrow, DW Goldstein, ME TI Effect on a laminar boundary layer of small-amplitude streamwise vorticity in the upstream flow SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TRANSITION; DISTURBANCES; TURBULENCE; INSTABILITY; EVOLUTION; WAVES AB This paper is a generalization of a previous analysis of the effects of a small-amplitude, steady, streamwise vorticity field on the flow over an infinitely thin flat plate in an otherwise uniform stream. That analysis, which is given in Goldstein & Leib (1993), required that the disturbance Reynolds number (i.e. the Reynolds number based on the disturbance velocity and length scale) be infinite while the present paper considers the more general case where this quantity can be finite. The results show how an initially linear perturbation of the upstream flow ultimately leads to a small-amplitude but nonlinear cross-flow far downstream from the leading edge. This flow can, under certain conditions, cause the streamwise velocity profiles to develop distinct shear layers in certain localized spanwise regions. These shear layers, which are remarkably similar to the ones that develop in Tollmien-Schlichting-wave transition (Kovasznay, Komoda & Vasudeva 1962), are highly inflectional and can therefore support the rapidly growing inviscid instabilities that are believed to break down into turbulent spots (Greenspan & Benney 1963, and, subsequently, many others). Numerical computations are carried out for input parameters which approximate the flow conditions of some recent experimental studies of the so-called Klebanoff-mode phenomenon. The results are used to explain some of the experimental observations, and, more importantly, to explain why the averaged quantities usually reported in these experiments do not correlate well with the turbulent-spot formation and therefore with the overall transition process. C1 Nyma Inc, Glenn Res Ctr Grp, Cleveland, OH 44135 USA. NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Wundrow, DW (reprint author), Ohio Aerosp Inst, 22800 Cedar Point Rd, Cleveland, OH 44142 USA. NR 49 TC 50 Z9 51 U1 1 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 USA SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JAN 10 PY 2001 VL 426 BP 229 EP 262 DI 10.1017/S0022112000002354 PG 34 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA 400YF UT WOS:000166899700009 ER PT J AU Bauschlicher, CW So, CR AF Bauschlicher, CW So, CR TI Using hydrogen and chlorine on Si(111) to store data SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GEOMETRY OPTIMIZATION AB The interaction of a pyridine molecule with H and Cl atoms on an Si(1 1 1) surface is studied using a cluster model in conjunction with the B3LYP/6-31G level of theory. Regardless of the type of the neighboring atoms, the interaction of the pyridine with a hydrogen atom is very different from its interaction with a chlorine atom. This system is discussed in terms of our atomic data storage proposal. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. Palo Alto High Sch, Palo Alto, CA 94301 USA. RP Bauschlicher, CW (reprint author), NASA, Ames Res Ctr, Mail Stop 230-3, Moffett Field, CA 94035 USA. OI So, Christopher/0000-0001-7572-778X NR 12 TC 4 Z9 4 U1 0 U2 0 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 JAN 5 PY 2001 VL 333 IS 1-2 BP 1 EP 5 DI 10.1016/S0009-2614(00)01340-3 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 394DD UT WOS:000166508000001 ER PT J AU Walch, SP Bauschlicher, CW Ricca, A Bakes, ELO AF Walch, SP Bauschlicher, CW Ricca, A Bakes, ELO TI On the reaction CH2O+NH3 -> CH2NH+H2O SO CHEMICAL PHYSICS LETTERS LA English DT Article ID COUPLED-CLUSTER THEORY; ELECTRON CORRELATION; INTERSTELLAR; MOLECULES; HYAKUTAKE; ICES; B2 AB We study the energetics of CH2O + NH3 -> CH2NH H2O in the gas phase at the B3LYP and CCSD(T) levels. This reaction is shown to have a sizeable barrier. Ionization of NH? reduces the barrier to about 5 kcal/mol. We also show that in water, a proton-catalyzed mechanism yields no barriers in excess of the reaction endothermicity. Since this reaction has been proposed as one of the steps in interstellar synthesis of glycine, the simplest amino acid, this work suggests that the formation of amino acids is occurring in and/or on interstellar water ice grains, and not in the gas phase. (C) 2001 Elsevier Science B.V. All rights reserved. C1 NASA, Ames Res Ctr, Space Technol Div, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, ELORET, Moffett Field, CA 94035 USA. NASA, Ames Res Ctr, SETI Inst, 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 25 TC 11 Z9 11 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 JAN 5 PY 2001 VL 333 IS 1-2 BP 6 EP 11 DI 10.1016/S0009-2614(00)01341-5 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA 394DD UT WOS:000166508000002 ER PT J AU Meier, DL Koide, S Uchida, Y AF Meier, DL Koide, S Uchida, Y TI Magnetohydrodynamic production of relativistic jets SO SCIENCE LA English DT Review ID DOUBLE RADIO-SOURCES; ACCRETION DISKS; BLACK-HOLE; ASTROPHYSICAL JETS; ACTIVE GALAXIES; GRS 1915+105; SIMULATIONS; STAR; SUPERNOVAE; MECHANISM AB A number of astronomical systems have been discovered that generate collimated flows of plasma with velocities close to the speed of light. In all cases, the central object is probably a neutron star or black hole and is either accreting material from other stars or is in the initial violent stages of formation. Supercomputer simulations of the production of relativistic jets have been based on a magnetohydrodynamic model, in which differential rotation in the system creates a magnetic coil that simultaneously expels and pinches some of the infalling material. The model may explain the basic features of observed jets, including their speed and amount of collimation, and some of the details in the behavior and statistics of different jet-producing sources. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. Toyama Univ, Fac Engn, Toyama 9308555, Japan. Tokyo Univ Sci, Dept Phys, Shinjuku Ku, Tokyo 162, Japan. RP Meier, DL (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. EM David.L.Meier@jpl.nasa.gov NR 53 TC 256 Z9 258 U1 2 U2 9 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 JAN 5 PY 2001 VL 291 IS 5501 BP 84 EP 92 DI 10.1126/science.291.5501.84 PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 389VJ UT WOS:000166259100038 PM 11141552 ER PT J AU Lissauer, JJ AF Lissauer, JJ TI Time for gas planets to grow SO NATURE LA English DT Editorial Material ID COMPANION C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Lissauer, JJ (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 9 TC 16 Z9 16 U1 0 U2 0 PU MACMILLAN PUBLISHERS LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD JAN 4 PY 2001 VL 409 IS 6816 BP 23 EP 24 DI 10.1038/35051182 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA 388HT UT WOS:000166175600018 PM 11343091 ER PT B AU Kimiaghalam, B Homaifar, A Suttikulvet, B Sayyarrodsari, B AF Kimiaghalam, B Homaifar, A Suttikulvet, B Sayyarrodsari, B GP IEEE IEEE IEEE TI A multi layered multi fuzzy inference systems for autonomous robot navigation and obstacle avoidance SO 10TH IEEE INTERNATIONAL CONFERENCE ON FUZZY SYSTEMS, VOLS 1-3: MEETING THE GRAND CHALLENGE: MACHINES THAT SERVE PEOPLE LA English DT Proceedings Paper CT 10th IEEE International Conference on Fuzzy Systems CY DEC 02-05, 2001 CL UNIV MELBOURNE, MELBOURNE, AUSTRALIA SP IEEE HO UNIV MELBOURNE DE mobile robot; collision avoidance; fuzzy systems ID LOGIC AB A multi-layered multi fuzzy logic controllers (MLMFLC) scheme is introduced to navigate the Khepera miniature mobile robot through obstacles and narrow opening hallways. Robots eight infrared proximity sensors are divided into three groups (left, right, and back sensors) and are fed to three fuzzy inference systems (FIS) in the first layer. The output of the first FIS group in the first layer is a representation of the robot's immediate surrounding obstacles. Three outputs of the three FIS in the first layer are the inputs of the second layer's FIS. Eventually, the output of the second layer FIS operates two step-motors according to position of the obstacles surrounding the robot. A total of nineteen rules have been employed for all FIS blocks. A real environment with obstacles and a dead-end trap has been used and experimental results on a real mobile robot have been demonstrated. By applying the controller, the robot moves smoothly in the experimental environment without any collision. Since the robot adjusts its speed in response to the environment, the overall speed is desirable. The design process and experimental set up is explained in detail. C1 NC A&T State Univ, Autonomous Control Engn Ctr, Dept Elect Engn, NASA, Greensboro, NC 27411 USA. RP Kimiaghalam, B (reprint author), NC A&T State Univ, Autonomous Control Engn Ctr, Dept Elect Engn, NASA, Greensboro, NC 27411 USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-7293-X PY 2001 BP 340 EP 343 PG 4 WC Automation & Control Systems; Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic; Imaging Science & Photographic Technology SC Automation & Control Systems; Computer Science; Engineering; Imaging Science & Photographic Technology GA BV21J UT WOS:000178178300085 ER PT B AU Berenji, HR Vengerov, D AF Berenji, HR Vengerov, D GP IEEE IEEE IEEE TI On convergence of fuzzy reinforcement learning SO 10TH IEEE INTERNATIONAL CONFERENCE ON FUZZY SYSTEMS, VOLS 1-3: MEETING THE GRAND CHALLENGE: MACHINES THAT SERVE PEOPLE LA English DT Proceedings Paper CT 10th IEEE International Conference on Fuzzy Systems CY DEC 02-05, 2001 CL UNIV MELBOURNE, MELBOURNE, AUSTRALIA SP IEEE HO UNIV MELBOURNE DE fuzzy reinforcement learning; convergence; actor-critic AB This paper provides the first convergence proof for Fuzzy Reinforcement Learning (FRL). We extend the work of Konda and Tsitsiklis (2000), who presented a convergent actor-critic (AC) algorithm for a general parameterized actor. In our work we prove that a fuzzy rulebase actor satisfies the necessary conditions that guarantee the convergence of its parameters to a local optimum. Our fuzzy rulebase uses TSK rules, Gaussian membership functions and product inference. C1 NASA, Ames Res Ctr, Intelligent Inference Syst Corp, Computat Sci Div, Mt View, CA 94035 USA. RP Berenji, HR (reprint author), NASA, Ames Res Ctr, Intelligent Inference Syst Corp, Computat Sci Div, MS 269-2, Mt View, CA 94035 USA. NR 15 TC 0 Z9 1 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-7293-X PY 2001 BP 618 EP 621 PG 4 WC Automation & Control Systems; Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic; Imaging Science & Photographic Technology SC Automation & Control Systems; Computer Science; Engineering; Imaging Science & Photographic Technology GA BV21J UT WOS:000178178300154 ER PT B AU Seraji, H AF Seraji, H GP IEEE IEEE IEEE TI Terrain-based robot navigation using multi-scale traversability indices SO 10TH IEEE INTERNATIONAL CONFERENCE ON FUZZY SYSTEMS, VOLS 1-3: MEETING THE GRAND CHALLENGE: MACHINES THAT SERVE PEOPLE LA English DT Proceedings Paper CT 10th IEEE International Conference on Fuzzy Systems CY DEC 02-05, 2001 CL UNIV MELBOURNE, MELBOURNE, AUSTRALIA SP IEEE HO UNIV MELBOURNE AB The concepts of Local, Regional, and Global Traversability Indices have been introduced recently [1, 8-9]. These indices represent the suitability of a terrain for traversal by a mobile robot at different scales of resolution. This paper utilizes these indices to develop a navigation strategy for a mobile robot traversing a challenging terrain. The traversability indices form the basis of three navigational behaviors; namely, Traverse-Local, Traverse-Regional, and Traverse-Global behaviors. These behaviors are blended with the Seek-Goal behavior to ensure that the mobile robot reaches the goal safety while avoiding obstacles and impassable terrain segments. The paper is concluded by an illustrative graphical simulation study(1). C1 CALTECH, Jet Prop Lab, NASA, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, NASA, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-7293-X PY 2001 BP 1309 EP 1314 PG 6 WC Automation & Control Systems; Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic; Imaging Science & Photographic Technology SC Automation & Control Systems; Computer Science; Engineering; Imaging Science & Photographic Technology GA BV21J UT WOS:000178178300325 ER PT B AU Hadaegh, FY Kang, BH Scharf, DP AF Hadaegh, FY Kang, BH Scharf, DP GP IEEE IEEE IEEE TI Rule-based formation estimation of distributed spacecraft SO 10TH IEEE INTERNATIONAL CONFERENCE ON FUZZY SYSTEMS, VOLS 1-3: MEETING THE GRAND CHALLENGE: MACHINES THAT SERVE PEOPLE LA English DT Proceedings Paper CT 10th IEEE International Conference on Fuzzy Systems CY DEC 02-05, 2001 CL UNIV MELBOURNE, MELBOURNE, AUSTRALIA SP IEEE HO UNIV MELBOURNE ID MULTIPLE SPACECRAFT AB This paper addresses an estimation problem specific to formation flying of spacecraft that can be approached with rule or logic based methodologies. A decentralized and self-centered framework of the estimator is formulated and shown to be a feasible estimation architecture under formation reconfiguration or formation member failures. A rule-based strategy is applied to the problem that switches the gain of the linear observer of the formation. Each gain set is derived from a constant gain linear observer optimized for either formation member acquisition or steady state operation. The formation member acquisition time can be critical when considering a dynamic formation reconfiguration followed by precision pointing required by scientific mission. This particular strategy has the advantages of onboard computational efficiency and fast filter convergence during formation initialization or formation member acquisition. A two-spacecraft simulation analysis was performed to demonstrate and validate the efficacy of the algorithm. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Hadaegh, FY (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 14 TC 0 Z9 0 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-7293-X PY 2001 BP 1331 EP 1336 PG 6 WC Automation & Control Systems; Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic; Imaging Science & Photographic Technology SC Automation & Control Systems; Computer Science; Engineering; Imaging Science & Photographic Technology GA BV21J UT WOS:000178178300330 ER PT B AU Mobasser, S Liebe, CC Howard, A AF Mobasser, S Liebe, CC Howard, A GP IEEE IEEE IEEE TI Fuzzy image processing in sun sensor SO 10TH IEEE INTERNATIONAL CONFERENCE ON FUZZY SYSTEMS, VOLS 1-3: MEETING THE GRAND CHALLENGE: MACHINES THAT SERVE PEOPLE LA English DT Proceedings Paper CT 10th IEEE International Conference on Fuzzy Systems CY DEC 02-05, 2001 CL UNIV MELBOURNE, MELBOURNE, AUSTRALIA SP IEEE HO UNIV MELBOURNE AB Sun sensors are widely used in spacecraft attitude determination subsystems to provide a measurement of the sun vector in spacecraft coordinates. At the Jet Propulsion Laboratory, California Institute of Technology, there is an ongoing research activity to utilize Micro Electro Mechanical Systems (MEMS) processes to develop a smaller and lighter sun sensor for space applications. A prototype sun sensor has been designed and constructed. It consists of a piece of silicon coated with a thin layer of chrome, and a layer of gold with hundreds of small pinholes, placed on top of an image detector at a distance of less than a millimeter. Images of the sun are formed on the detector when the sun illuminates the assembly. Software algorithms must be able to identify the individual pinholes on the image detector and calculate the angle to the sun. Fuzzy image processing is utilized in this process. This paper will describe how the fuzzy image processing is implemented in the instrument. Also a camera pin hole model is constructed and used to evaluate the accuracy of the sun sensor. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Mobasser, S (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 6 TC 2 Z9 2 U1 0 U2 0 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA BN 0-7803-7293-X PY 2001 BP 1337 EP 1342 PG 6 WC Automation & Control Systems; Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic; Imaging Science & Photographic Technology SC Automation & Control Systems; Computer Science; Engineering; Imaging Science & Photographic Technology GA BV21J UT WOS:000178178300331 ER PT B AU Follen, G Kim, C Lopez, I Sang, J Townsend, S AF Follen, G Kim, C Lopez, I Sang, J Townsend, S GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI A CORBA-based development environment for wrapping and coupling legacy scientific codes SO 10TH IEEE INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE DISTRIBUTED COMPUTING, PROCEEDINGS LA English DT Proceedings Paper CT 10th Annual IEEE International Symposium on High Performance Distributed Computing CY AUG 07-09, 2001 CL SAN FRANCISCO, CA SP IEEE Comp Soc, Tech Comm Distributed Processing, Univ Arizona, Microsoft, NASA Ames Res Ctr, IBM, Argonne Natl Lab, Lawrence Berkeley Natl Lab AB Within NASA's High Performance Computing and Communication (HPCC) program, the NASA Glenn Research Center(GRC) is developing a large scale, detailed simulation environment for the analysis and design of aircraft engines called the Numerical Propulsion System Siniulation (NPSS). The three major aspects of modeling capabilities focused in NPSS, including integration of different engine components, coupling of multiple disciplines, and engine component zooming at appropriate level of fidelity, require relatively tight coupling of different analysis codes. Most of these codes in aerodynamics and solid mechanics are written in Fortran, Refitting these legacy Fortran codes with distributed objects can increase these codes reusability. In this paper we describe our experiences in building a CORBA-based development environment for programmers to easily wrap and couple legacy Fortran codes. This environment consists of a C++ wrapper library to hide the details of CORBA and an efficient remote variable scheme to facilitate data exchange between the client and the server. We also report empirical performance evaluation results and describe current applications. C1 NASA, Glenn Res Ctr, Cleveland, OH 44135 USA. RP Follen, G (reprint author), NASA, Glenn Res Ctr, 21000 Brookpk Rd, Cleveland, OH 44135 USA. NR 24 TC 1 Z9 1 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 USA BN 0-7695-1296-8 PY 2001 BP 22 EP 31 PG 4 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BT53X UT WOS:000173292600003 ER PT B AU Frumkin, M Van der Wijngaart, RF AF Frumkin, M Van der Wijngaart, RF GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI NAS Grid Benchmarks: A tool for Grid space exploration SO 10TH IEEE INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE DISTRIBUTED COMPUTING, PROCEEDINGS LA English DT Proceedings Paper CT 10th Annual IEEE International Symposium on High Performance Distributed Computing CY AUG 07-09, 2001 CL SAN FRANCISCO, CA SP IEEE Comp Soc, Tech Comm Distributed Processing, Univ Arizona, Microsoft, NASA Ames Res Ctr, IBM, Argonne Natl Lab, Lawrence Berkeley Natl Lab AB We present a benchmark suite for computational Grids. It is based on the NAS Parallel Benchmarks (NPB) and is called NAS Grid Benchmark (NGB) in this paper We present NGB as a data flow graph encapsulating an instance of an NPB code in each graph node, which communicates with other nodes by sending/receiving initialization data. These nodes may be mapped to the same or different Grid machines. Like NPB, NGB specifies several different classes (problem sizes). NGB also specifies the generic Grid services sufficient for running the suite. The implementor has the freedom to choose any Grid environment. We describe a reference implementation in Java, and present some scenarios for using NGB. C1 NASA, Ames Res Ctr, Adv Supercomp Div, Moffett Field, CA 94035 USA. RP Frumkin, M (reprint author), NASA, Ames Res Ctr, Adv Supercomp Div, MS T27A-2, Moffett Field, CA 94035 USA. NR 16 TC 2 Z9 3 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 0-7695-1296-8 PY 2001 BP 315 EP 322 DI 10.1109/HPDC.2001.945199 PG 4 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BT53X UT WOS:000173292600029 ER PT B AU Manduchi, R Matthies, L Pollara, F AF Manduchi, R Matthies, L Pollara, F BE Ardizzone, E DiGesu, V TI From cross-country autonomous navigation to intelligent deep space communications: Visual sensor processing at JPL SO 11TH INTERNATIONAL CONFERENCE ON IMAGE ANALYSIS AND PROCESSING, PROCEEDINGS LA English DT Proceedings Paper CT 11th International Conference on Image Analysis and Processing CY SEP 26-28, 2001 CL PALERMO, ITALY SP Int Assoc Pattern Recognit, Univ Palermo, Italian Council Res AB We describe ongoing work at JPL in two fields: autonomous navigation for terrestrial vehicles, and prioritized progressive transmission for deep space communications. While such applications may seem rather disparate, the), have in common the need for autonomous reasoning about visual information. We first review a number of techniques currently, under development that make use of data from color and infrared cameras, multispectral sensors, and laser rangefinder for estimating properties of the terrain cover in outdoor vegetated terrain. We then discuss how onboard visual analysis mechanisms for Mars rovers can be used for prioritizing the data to be transmitted to Earth, in order to maximize the science return of a mission. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 15 TC 1 Z9 1 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 0-7695-1183-X; 0-7695-1184-8 PY 2001 BP 472 EP 477 PG 6 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BT38P UT WOS:000172833500076 ER PT B AU Schmidlin, FJ AF Schmidlin, FJ GP AMS AMS TI Improved humidity sensing with the chilled mirror: Really? SO 11TH SYMPOSIUM ON METEOROLOGICAL OBSERVATIONS AND INSTRUMENTATION LA English DT Proceedings Paper CT 11th Symposium on Meteorological Observations and Instrumentation CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Wallops Isl, Wallops Isl, VA 23337 USA. RP Schmidlin, FJ (reprint author), Wallops Flight Facil, Observ Sci Branch, Wallops Isl, VA 23337 USA. NR 5 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 15 EP 18 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences GA BV01N UT WOS:000177602400005 ER PT B AU Bourras, D Eymard, L Liu, WT AF Bourras, D Eymard, L Liu, WT GP AMS AMS TI A neural network to retrieve the mesoscale instantaneous latent heat flux over oceans from SSM/I observations. SO 11TH SYMPOSIUM ON METEOROLOGICAL OBSERVATIONS AND INSTRUMENTATION LA English DT Proceedings Paper CT 11th Symposium on Meteorological Observations and Instrumentation CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc ID SURFACE FLUXES; TOGA COARE; WIND-SPEED; WATER; ATMOSPHERE C1 NASA, JPL, Pasadena, CA USA. RP Bourras, D (reprint author), NASA, JPL, Pasadena, CA USA. NR 16 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 55 EP 59 PG 5 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences GA BV01N UT WOS:000177602400013 ER PT B AU Schmidlin, FJ AF Schmidlin, FJ GP AMS AMS TI ECC ozonesonde calibration and observations: Satellite validation SO 11TH SYMPOSIUM ON METEOROLOGICAL OBSERVATIONS AND INSTRUMENTATION LA English DT Proceedings Paper CT 11th Symposium on Meteorological Observations and Instrumentation CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Wallops Isl, Wallops Isl, VA 23337 USA. RP Schmidlin, FJ (reprint author), Wallops Flight Facil, Oberv Sci Branch, Wallops Isl, VA 23337 USA. NR 0 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 110 EP 113 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences GA BV01N UT WOS:000177602400024 ER PT B AU Wright, CW French, JR AF Wright, CW French, JR GP AMS AMS TI Comparison of aircraft attitude determination by GPS, INS, and airborne laser: preliminary results SO 11TH SYMPOSIUM ON METEOROLOGICAL OBSERVATIONS AND INSTRUMENTATION LA English DT Proceedings Paper CT 11th Symposium on Meteorological Observations and Instrumentation CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Wallops Isl, VA 23337 USA. RP Wright, CW (reprint author), NASA, Goddard Space Flight Ctr, Bldg N-159,Rm E117,Code 972, Wallops Isl, VA 23337 USA. NR 2 TC 0 Z9 0 U1 1 U2 1 PU AMER METEOROLOGICAL SOCIETY PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108 USA PY 2001 BP 134 EP 138 PG 5 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences GA BV01N UT WOS:000177602400029 ER PT B AU Lin, B Minnis, P Fang, A Young, D AF Lin, B Minnis, P Fang, A Young, D GP AMS AMS TI Estimation of column water amounts over arctic regions using ground-based thermal microwave and infrared measurements SO 11TH SYMPOSIUM ON METEOROLOGICAL OBSERVATIONS AND INSTRUMENTATION LA English DT Proceedings Paper CT 11th Symposium on Meteorological Observations and Instrumentation CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc ID CLOUD C1 NASA Langley Res Ctr, Atmospher Sci Res, Hampton, VA 23681 USA. RP Lin, B (reprint author), NASA Langley Res Ctr, Atmospher Sci Res, MS420, Hampton, VA 23681 USA. NR 8 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 168 EP 170 PG 3 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences GA BV01N UT WOS:000177602400036 ER PT B AU Chiou, EW Chu, WP Thomason, LW AF Chiou, EW Chu, WP Thomason, LW GP AMS AMS TI Improved water vapor retrieval algorithm for the sage III experiment SO 11TH SYMPOSIUM ON METEOROLOGICAL OBSERVATIONS AND INSTRUMENTATION LA English DT Proceedings Paper CT 11th Symposium on Meteorological Observations and Instrumentation CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Chiou, EW (reprint author), NASA, Langley Res Ctr, Mail Stop 475, Hampton, VA 23681 USA. NR 4 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 301 EP 306 PG 6 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences GA BV01N UT WOS:000177602400069 ER PT B AU Suggs, RJ Lapenta, WM Jedlovec, GJ Haines, SL AF Suggs, RJ Lapenta, WM Jedlovec, GJ Haines, SL GP AMS AMS TI Intercomparison of GOES-8 imager and sounder land surface temperature retrievals SO 11TH SYMPOSIUM ON METEOROLOGICAL OBSERVATIONS AND INSTRUMENTATION LA English DT Proceedings Paper CT 11th Symposium on Meteorological Observations and Instrumentation CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, MSFC, Global Hydrol & Climate Ctr, NSSTC, Huntsville, AL 35805 USA. RP Suggs, RJ (reprint author), NASA, MSFC, Global Hydrol & Climate Ctr, NSSTC, 320 Sparkman Dr, Huntsville, AL 35805 USA. NR 4 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 362 EP 365 PG 4 WC Instruments & Instrumentation; Meteorology & Atmospheric Sciences SC Instruments & Instrumentation; Meteorology & Atmospheric Sciences GA BV01N UT WOS:000177602400082 ER PT B AU Entin, JK Houser, P Toll, D Radakovich, J Cosgrove, B AF Entin, JK Houser, P Toll, D Radakovich, J Cosgrove, B GP AMS AMS TI Resolution and spatial compatibility issues in land surface modeling SO 12TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 12th Symposium on Global Change and Climate Variations CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Greenbelt, MD 20771 USA. RP Entin, JK (reprint author), NASA, Goddard Space Flight Ctr, Hydrol Sci Branch, Mail Code 974, Greenbelt, MD 20771 USA. RI Houser, Paul/J-9515-2013 OI Houser, Paul/0000-0002-2991-0441 NR 0 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 88 EP 89 PG 2 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV01M UT WOS:000177601900027 ER PT B AU Bosilovich, MG Schubert, SD AF Bosilovich, MG Schubert, SD GP AMS AMS TI Water vapor tracers as diagnostics for the regional hydrologic cycle SO 12TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 12th Symposium on Global Change and Climate Variations CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc ID PRECIPITATION C1 NASA, Goddard Space Flight Ctr, Data Assimilat Off, Greenbelt, MD 20771 USA. RP Bosilovich, MG (reprint author), NASA, Goddard Space Flight Ctr, Data Assimilat Off, Code 910-3, Greenbelt, MD 20771 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 90 EP 93 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV01M UT WOS:000177601900028 ER PT B AU Wong, T Wielicki, BA Young, DF AF Wong, T Wielicki, BA Young, DF GP AMS AMS TI Decadal variability in tropical broadband radiation budget SO 12TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 12th Symposium on Global Change and Climate Variations CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc ID EARTH C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Wong, T (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. NR 4 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 210 EP 213 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV01M UT WOS:000177601900066 ER PT B AU Minnis, P Ayers, JK Palikondra, R Doelling, DR Schumann, U Gierens, K AF Minnis, P Ayers, JK Palikondra, R Doelling, DR Schumann, U Gierens, K GP AMS AMS TI Changes in cirrus cloudiness and their relationship to contrails SO 12TH SYMPOSIUM ON GLOBAL CHANGE AND CLIMATE VARIATIONS LA English DT Proceedings Paper CT 12th Symposium on Global Change and Climate Variations CY JAN 14-18, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc ID GLOBAL DISTRIBUTION C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Minnis, P (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. NR 11 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 239 EP 242 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA BV01M UT WOS:000177601900075 ER PT S AU Yang, EH Wiberg, DV AF Yang, EH Wiberg, DV GP IEEE IEEE IEEE TI A new wafer-level membrane transfer technique for MEMS deformable mirrors SO 14TH IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, TECHNICAL DIGEST SE PROCEEDINGS: IEEE MICRO ELECTRO MECHANICAL SYSTEMS WORKSHOP LA English DT Proceedings Paper CT 14th IEEE International Conference on Micro Electro Mechanical Systems (MEMS 2001) CY JAN 21-25, 2001 CL INTERLAKEN, SWITZERLAND SP IEEE, Robot & Automat Soc, ACREO AB, AMMT GmbH Adv Micromachining Tools, Austria Mikro Syst Int AG, Alcatel Vacuum Technol, Cronos Integrated Microsyst, CSEM (Colibrys), Elsevier Sci Sensors & Actuators, ESEC SA, ETH Zurich, ETH Zurich, Phys Electr Lab, EV Grp, IBM, Zurich Res Lab, Infineon Technologies AG, IntelliSense Corp, IVAM NRW ev, Karl Suss KG GmbH & Co, Kluwer Acad Publishers, MEMS Ind Grp, MEMSCAP SA, MEMSleadership.com, Micro Chem Corp, Microcosm Technologies Inc, Micro Resist Technol GmbH, Oxford Instruments GmbH Plasma Technol, R&D Magazine Micromachine Devices, SC Fluids Inc, Sensile Technologies SA, Sensirion AG, Stand MEMS Inc, Surface Technol Syst Ltd, Technol Manaagement Gruppe, USAF, European Off Aerosp Res & Dev, Univ Neuchatel, Sensors, Actuators & Microsyst Lab, IMT, Visteon, Wiley VCH, XACTIX Inc, Zuhlke Engn AG AB This paper describes a new technique for transferring an entire wafer-level silicon membrane from one substrate to another. A I mum thick silicon membrane, 100 mm in diameter, has been successfully transferred without using adhesives or polymers (i.e. wax, epoxy, or photoresist). Smaller or larger diameter membranes can also be transferred using this technique. The fabricated actuator membrane with an electrode gap of 1.50 mum shows a vertical deflection of 0.37 mum at 55 V. The proposed technique has the following benefits over those previously reported: 1) No post-assembly release process (e.g. using HF) is required, and no wax, photoresist, or epoxy is used for the transfer purpose 2) The bonded interface is completely isolated from any acid, etchant, or solvent, which ensures a clean and flat membrane surface. 3) It offers the capability of transferring wafer-level membranes over deformable actuators. C1 Jet Prop Lab, Device Res & Applicat Sect, Pasadena, CA 91109 USA. RP Yang, EH (reprint author), Jet Prop Lab, Device Res & Applicat Sect, 4800 Oak Grove De, Pasadena, CA 91109 USA. OI Yang, Eui-Hyeok/0000-0003-4893-1691 NR 13 TC 3 Z9 3 U1 0 U2 1 PU IEEE PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 USA SN 1084-6999 BN 0-7803-5999-2 J9 PROC IEEE MICR ELECT PY 2001 BP 80 EP 83 DI 10.1109/MEMSYS.2001.906483 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA BR57C UT WOS:000166833600020 ER PT S AU Schauer, AG Schmidlin, FJ AF Schauer, AG Schmidlin, FJ BE Warmbein, B TI Data comparison of HRDI wind and temperature data with rocket-borne falling spheres SO 15TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 15th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 28-31, 2001 CL BIARRITZ, FRANCE SP European Space Agcy AB Correlative measurements for the High Resolution Doppler Imager (HRDI) on board the Upper Atmospheric Research Satellite (UARS) have been obtained from several sites. NASA Wallops Flight Facility, (WFF), has the lengthiest series of measurements; the other sites have data from short campaigns. Failing spheres launched during overpasses of HRDI are compared to temperature and wind data from HRDI. There are several dozen successful correlative measurements spanning from early in the UARS data series through 1996. The results of the inflatable failing sphere measurements are examined against the HRDI data to see how comparable the wind and temperature measurements are over the overlapping altitude ranges (roughly 60-90 km). While individual comparisons show varying degrees of agreement, averages for each location or by year compare well, generally within the stated goal of accuracy for HRDI. C1 Sci & Engn Serv Inc, Wallops Flight Facil, Wallops Isl, VA 23337 USA. RP Schauer, AG (reprint author), Sci & Engn Serv Inc, Wallops Flight Facil, Wallops Isl, VA 23337 USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU ESA PUBLICATIONS DIVISION C/O ESTEC PI 2200 AG NOORDWIJK PA PO BOX 299, 2200 AG NOORDWIJK, NETHERLANDS SN 0379-6566 BN 92-9092-725-9 J9 ESA SP PUBL PY 2001 VL 471 BP 85 EP 89 PG 5 WC Engineering, Aerospace; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA BT34U UT WOS:000172696400012 ER PT S AU Schmidlin, FJ Remsberg, E Beebe, A Lingenfelser, G AF Schmidlin, FJ Remsberg, E Beebe, A Lingenfelser, G BE Warmbein, B TI HALOE temperature data comparison with rocket-borne falling sphere temperatures SO 15TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 15th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 28-31, 2001 CL BIARRITZ, FRANCE SP European Space Agcy AB Recent comparison of upper stratospheric and mesospheric temperatures measured with the HALOE instrument on UARS and the rocket-borne Passive Inflatable Failing Sphere (PIFS) launched from NASA's Wallops Island revealed comparability. Temperature bias of up to 10 K between 68 and 72 kin was noted but reprocessing of the sphere's radar measurements has reduced the magnitude of the bias. HALOE temperature profiles are verified as being similar to those of the PIFS, agreeing within 5-7 K over the range of 30-87 km. HALOE sunrise-sunset mean temperatures are discussed for mid- and high-latitude observation sets. HALOE mid-latitude profiles illustrate a wavelength in the upper stratosphere of about 30 kin, similar to what would be expected from a diurnal wavelength. High-latitude profiles reveal small sunrise-sunset differences below 70 km and about I I K above. The analysis used to prepare this report verifies that HALOE's measurements are similar to those of meteorological rocket launched close in space and time to the satellite's ephemeris and should be used to extend specific databases especially at those locations no longer launching meteorological rockets. C1 NASA, Goddard Space Flight Ctr, Obsservat Sci Branch, Wallops Isl, VA 23337 USA. RP Schmidlin, FJ (reprint author), NASA, Goddard Space Flight Ctr, Obsservat Sci Branch, Wallops Isl, VA 23337 USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU ESA PUBLICATIONS DIVISION C/O ESTEC PI 2200 AG NOORDWIJK PA PO BOX 299, 2200 AG NOORDWIJK, NETHERLANDS SN 0379-6566 BN 92-9092-725-9 J9 ESA SP PUBL PY 2001 VL 471 BP 91 EP 96 PG 6 WC Engineering, Aerospace; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA BT34U UT WOS:000172696400013 ER PT S AU Goldberg, RA Pfaff, RF Holzworth, RH Schmidlin, FJ Voss, HD Tuzzolino, AJ Croskey, CL Mitchell, JD Friedrich, M Murtagh, D Witt, G Gumbel, J von Zahn, U Singer, W Hoppe, UP AF Goldberg, RA Pfaff, RF Holzworth, RH Schmidlin, FJ Voss, HD Tuzzolino, AJ Croskey, CL Mitchell, JD Friedrich, M Murtagh, D Witt, G Gumbel, J von Zahn, U Singer, W Hoppe, UP BE Warmbein, B TI The DROPPS mission: A study of the Polar Summer Mesosphere with rocket, radar and lidar SO 15TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 15th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 28-31, 2001 CL BIARRITZ, FRANCE SP European Space Agcy ID NOCTILUCENT CLOUDS; CHARGED DUST; MESOPAUSE; ECHOES; PERFORMANCE AB DROPPS (The Distribution and Role of Particles in the Polar Summer Mesosphere), a highly coordinated international study conducted in July, 1999. involved two sequences of rockets launched from the Norwegian rocket range in Andoya, Norway. These studies were designed to investigate the properties of the polar summer mesosphere, particularly relating to polar mesospheric summer echoes (PMSE) and their possible relationship to particles (aerosol and dust layers) and to noctilucent clouds (NLC). Each of the two sequences included a DROPPS NASA-Black Brant payload, consisting of an array of instruments to measure the electrodynamic and optical structure of the mesosphere and lower thermosphere. These were provided by participants from several US and European scientific laboratories. The DROPPS payloads were each accompanied by a sequence of several European payloads (MIDAS, Mini-MIDAS, and Mini-DUSTY) designed to study electrodynamic structure of the same region, and by several meteorological rockets to provide wind and temperature data in the critical region of study. ALOMAR Lidars, and MF and MST Radars (all located adjacent to the Andoya launch site) were used to continuously monitor the mesosphere for NLCs and PMSEs, respectively. EISCAT VHF radar (Tromso, Norway) provided similar information about PMSEs, about 130 km downstream from Andoya. Sequence was launched during the night of 5-6 July into a strong PMSE display with a weak NLC at the base of the PMSE. Sequence 2 was launched on the early morning of 14 July into a strong NLC, but surprisingly with no PMSE evident. Of note is the observed presence of negatively charged particles within the PMSE region but absent from the NLC. The PMSE layer also contained electrodynamic turbulence, which was absent within the NLC observed during Sequence 2. As noted above, DROPPS was designed to investigate the origin of PMSEs and how they might relate to NLCs. By comparison of data acquired on a night exhibiting a strong PMSE and weak NLC with one showing a strong NLC with no PMSE, the observations show consistencies with theories dependent on the existence of charged aerosols. This necessary but insufficient condition was established with the PID and blunt probes aboard each DROPPS payload. Probe data demonstrated the scavenging of free electrons to produce the charged aerosols. The measurement of plasma irregularities for DROPPS I but not DROPPS 2 was observed by the AC electric field experiment. The meteorological data also indicated a possible origin for uplifting during the DROPPS I period, but absent during DROPPS 2. Finally, Ne in the region of interest was significantly higher during DROPPS 1, caused by energetic electron precipitation during a geomagnetically active period. All of these conditions are necessary, but each insufficient for PMSEs to occur; most were absent during DROPPS 2. This paper provides an overview of the program and discusses the above findings. C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Goldberg, RA (reprint author), NASA, Goddard Space Flight Ctr, Code 690, Greenbelt, MD 20771 USA. RI Goldberg, Richard /E-1881-2012; Pfaff, Robert/F-5703-2012; OI Pfaff, Robert/0000-0002-4881-9715; /0000-0003-1539-3559 NR 27 TC 0 Z9 0 U1 0 U2 0 PU ESA PUBLICATIONS DIVISION C/O ESTEC PI 2200 AG NOORDWIJK PA PO BOX 299, 2200 AG NOORDWIJK, NETHERLANDS SN 0379-6566 BN 92-9092-725-9 J9 ESA SP PUBL PY 2001 VL 471 BP 157 EP 164 PG 8 WC Engineering, Aerospace; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA BT34U UT WOS:000172696400024 ER PT S AU Cathey, HM AF Cathey, HM BE Warmbein, B TI NASA super-pressure balloons - Designing to meet the future SO 15TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 15th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 28-31, 2001 CL BIARRITZ, FRANCE SP European Space Agcy AB The NASA Ultra Long Duration Balloon project presents a new challenge in balloon design by extending flight duration for large heavy payloads. The pumpkin balloon design is innovative and presents many new challenges. This paper encapsulates the NASA Ultra Long Duration Balloon Vehicle developments, presents them to the Science Community, and shows points of interaction with the users. The capabilities and limitations are presented to allow potential users to make informed choices in the development of balloon class payloads. Brief summaries of test flights and the cause and effect relationship between suspended load and float altitude are presented. A focus on innovation and the future using the Ultra Long Duration Balloon super-pressure balloon technology is also presented. C1 New Mexico State Univ, Phys Sci Lab, NASA, GSFC,Wallops Flight Facil,NASA Balloon Program Of, Wallops Isl, VA 23337 USA. RP Cathey, HM (reprint author), New Mexico State Univ, Phys Sci Lab, NASA, GSFC,Wallops Flight Facil,NASA Balloon Program Of, Wallops Isl, VA 23337 USA. NR 3 TC 1 Z9 1 U1 0 U2 0 PU ESA PUBLICATIONS DIVISION C/O ESTEC PI 2200 AG NOORDWIJK PA PO BOX 299, 2200 AG NOORDWIJK, NETHERLANDS SN 0379-6566 BN 92-9092-725-9 J9 ESA SP PUBL PY 2001 VL 471 BP 583 EP 590 PG 8 WC Engineering, Aerospace; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA BT34U UT WOS:000172696400098 ER PT S AU Kerzhanovich, VV Cutts, JA AF Kerzhanovich, VV Cutts, JA BE Warmbein, B TI Recent progress in planetary balloons SO 15TH ESA SYMPOSIUM ON EUROPEAN ROCKET AND BALLOON PROGRAMMES AND RELATED RESEARCH, PROCEEDINGS SE ESA SPECIAL PUBLICATIONS LA English DT Proceedings Paper CT 15th ESA Symposium on European Rocket and Balloon Programmes and Related Research CY MAY 28-31, 2001 CL BIARRITZ, FRANCE SP European Space Agcy AB In the last 15 years several balloon mission concepts have been proposed for Mars and Venus, one of them - Russian-French Mars Aerostat - was extensively developed in 1988-1995 but was terminated before completion. It became clear that a number of critical technologies still needed to be developed prior to committing a costly space mission, In recent years significant progress has been made in two critical fields: aerial deployment and inflation of thin-film balloons for specific planetary applications, and in the development of envelope design for stratospheric applications. This paper describes requirements, proposed concepts, critical elements and trade-offs in planetary balloon missions as well as current results of some of JPL balloon programs. C1 CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA. RP Kerzhanovich, VV (reprint author), CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA. NR 18 TC 0 Z9 0 U1 0 U2 0 PU ESA PUBLICATIONS DIVISION C/O ESTEC PI 2200 AG NOORDWIJK PA PO BOX 299, 2200 AG NOORDWIJK, NETHERLANDS SN 0379-6566 BN 92-9092-725-9 J9 ESA SP PUBL PY 2001 VL 471 BP 647 EP 652 PG 6 WC Engineering, Aerospace; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA BT34U UT WOS:000172696400109 ER PT B AU Lowry, M Pressburger, T Rosu, G AF Lowry, M Pressburger, T Rosu, G GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Certifying domain-specific policies SO 16TH ANNUAL INTERNATIONAL CONFERENCE ON AUTOMATED SOFTWARE ENGINEERING (ASE 2001), PROCEEDINGS LA English DT Proceedings Paper CT 16th IEEE Annual International Conference on Automated Software Engineering (ASE 2001) CY NOV 26-29, 2001 CL CORONADO ISL, CA SP IEEE Comp Soc Tech Comm Software Engn, ACM SIGSoft, ACM SIGArt ID EQUATIONAL LOGIC; ALGEBRA AB Proof-checking code for compliance to safety policies potentially enables a product-oriented approach to certain aspects of software certification. To date, previous research has focused on generic, low-level programming-language properties such as memory type safety. In this paper we consider proof-checking higher-level domain-specific properties for compliance to safety policies. The paper first describes a framework related to abstract interpretation in which compliance to a class of certification policies can be efficiently calculated. Membership equational logic is shown to provide a rich logic for carrying out such calculations, including partiality, for certification. The architecture for a domain-specific certifier is described, followed by an implemented case study. The case study considers consistency of abstract variable attributes in code that performs geometric calculations in Aerospace systems. C1 NASA, Ames Res Ctr, Automated Software Engn Grp, Moffett Field, CA 94035 USA. RP Lowry, M (reprint author), NASA, Ames Res Ctr, Automated Software Engn Grp, Moffett Field, CA 94035 USA. NR 14 TC 6 Z9 6 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 0-7695-1427-8 PY 2001 BP 81 EP 90 DI 10.1109/ASE.2001.989793 PG 10 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BT44D UT WOS:000173027200009 ER PT B AU Havelund, K Rosu, G AF Havelund, K Rosu, G GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Monitoring programs using rewriting SO 16TH ANNUAL INTERNATIONAL CONFERENCE ON AUTOMATED SOFTWARE ENGINEERING (ASE 2001), PROCEEDINGS LA English DT Proceedings Paper CT 16th IEEE Annual International Conference on Automated Software Engineering (ASE 2001) CY NOV 26-29, 2001 CL CORONADO ISL, CA SP IEEE Comp Soc Tech Comm Software Engn, ACM SIGSoft, ACM SIGArt AB We present a rewriting algorithm for efficiently testing future time Linear Temporal Logic (LTL)formulae on finite execution traces. The standard models of LTL are infinite traces, reflecting the behavior of reactive and concurrent systems which conceptually may be continuously alive. In most past applications of LTL, theorem provers and model checkers have been used to formally prove that down-scaled models satisfy such LTL specifications. Our goal is instead to use LTL for up-scaled testing of real software applications, corresponding to analyzing the conformance of finite traces against LTL formulae. We first describe what it means for a finite trace to satisfy an LTL formula and then suggest an optimized algorithm based on transforming LTL formulae. We use the Maude rewriting logic, which turns out to be a good notation and being supported by an efficient rewriting engine for performing these experiments. The work constitutes part of the Java PathExplorer (JPAX) project, the purpose of which is to develop a flexible tool for monitoring Java program executions. C1 NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Havelund, K (reprint author), NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 28 TC 44 Z9 48 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 0-7695-1427-8 PY 2001 BP 135 EP 143 DI 10.1109/ASE.2001.989799 PG 9 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BT44D UT WOS:000173027200015 ER PT B AU Brat, G Visser, W AF Brat, G Visser, W GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Combining static analysis and model checking for software analysis SO 16TH ANNUAL INTERNATIONAL CONFERENCE ON AUTOMATED SOFTWARE ENGINEERING (ASE 2001), PROCEEDINGS LA English DT Proceedings Paper CT 16th IEEE Annual International Conference on Automated Software Engineering (ASE 2001) CY NOV 26-29, 2001 CL CORONADO ISL, CA SP IEEE Comp Soc Tech Comm Software Engn, ACM SIGSoft, ACM SIGArt AB We present an iterative technique in which model checking and static analysis are combined to verify large software systems. The rote of the static analysis is to compute partial order information which the model checker uses to reduce the state space. During exploration, the model checker also computes aliasing information that it gives to the static analyzer which can then refine its, analysis. The result of this refined analysis is then fed back to the model checker which updates its partial order reduction. At each step of this iterative process, the static analysis computes optimistic information which results in an unsafe reduction of the state space. However we show that the process converges to a fixed point at which time the partial order information is safe. and the whole state space is explored. C1 Kestrel NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Brat, G (reprint author), Kestrel NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. NR 13 TC 7 Z9 8 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 0-7695-1427-8 PY 2001 BP 262 EP 269 DI 10.1109/ASE.2001.989812 PG 8 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BT44D UT WOS:000173027200028 ER PT B AU Whittle, J Van Baalen, JR Schumann, J Robinson, P Pressburger, T Penix, J Oh, P Lowry, M Brat, G AF Whittle, J Van Baalen, JR Schumann, J Robinson, P Pressburger, T Penix, J Oh, P Lowry, M Brat, G GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Amphion/NAV: Deductive synthesis of state estimation software SO 16TH ANNUAL INTERNATIONAL CONFERENCE ON AUTOMATED SOFTWARE ENGINEERING (ASE 2001), PROCEEDINGS LA English DT Proceedings Paper CT 16th IEEE Annual International Conference on Automated Software Engineering (ASE 2001) CY NOV 26-29, 2001 CL CORONADO ISL, CA SP IEEE Comp Soc Tech Comm Software Engn, ACM SIGSoft, ACM SIGArt C1 Univ Wyoming, Kestrel Tech, QSS, NASA,RIACS,ASE Grp, Laramie, WY 82071 USA. RP Univ Wyoming, Kestrel Tech, QSS, NASA,RIACS,ASE Grp, Laramie, WY 82071 USA. NR 9 TC 5 Z9 5 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 0-7695-1426-X; 0-7695-1427-8 PY 2001 BP 395 EP 399 DI 10.1109/ASE.2001.989837 PG 5 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BT44D UT WOS:000173027200053 ER PT B AU Giannakopoulou, D Havelund, M AF Giannakopoulou, D Havelund, M GP IEEE COMPUTER SOCIETY IEEE COMPUTER SOCIETY TI Automata-based verification of temporal properties on running programs SO 16TH ANNUAL INTERNATIONAL CONFERENCE ON AUTOMATED SOFTWARE ENGINEERING (ASE 2001), PROCEEDINGS LA English DT Proceedings Paper CT 16th IEEE Annual International Conference on Automated Software Engineering (ASE 2001) CY NOV 26-29, 2001 CL CORONADO ISL, CA SP IEEE Comp Soc Tech Comm Software Engn, ACM SIGSoft, ACM SIGArt AB This paper presents an approach to checking a running program against Linear Temporal Logic (LTL) specifications. LTL is a widely used logic for expressing properties of programs viewed as sets of executions. Our approach consists of translating LTL formulae to finite-state automata, which are used as observers of the program behavior. The translation algorithm we propose modifies standard LTL to Biichi automata conversion techniques to generate automata that check finite program traces. The algorithm has been implemented in a tool, which has been integrated with the generic JPaX framework for runtime analysis of Java programs. C1 NASA, Ames Res Ctr, Automated Software Engn Grp, Moffett Field, CA 94035 USA. RP NASA, Ames Res Ctr, Automated Software Engn Grp, Moffett Field, CA 94035 USA. EM dimitra@email.arc-nasa.orov; havelund@email.arc-nasa.orov NR 13 TC 31 Z9 32 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 0-7695-1426-X; 0-7695-1427-8 PY 2001 BP 412 EP 416 PG 5 WC Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA BT44D UT WOS:000173027200057 ER PT B AU Pfister, R AF Pfister, R GP AMS AMS TI The information management system of NASA's EOS data and information system SO 17TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 17th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 14-19, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Pfister, R (reprint author), NASA, Goddard Space Flight Ctr, Code 423, Greenbelt, MD 20771 USA. NR 0 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 161 EP 163 PG 3 WC Meteorology & Atmospheric Sciences; Oceanography; Water Resources SC Meteorology & Atmospheric Sciences; Oceanography; Water Resources GA BV02Z UT WOS:000177651500043 ER PT B AU McDonald, KR Suresh, R Di, LP AF McDonald, KR Suresh, R Di, LP GP AMS AMS TI The Data and Information Access Link (DIAL) SO 17TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 17th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 14-19, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP McDonald, KR (reprint author), NASA, Goddard Space Flight Ctr, Code 423, Greenbelt, MD 20771 USA. NR 5 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 164 EP 166 PG 3 WC Meteorology & Atmospheric Sciences; Oceanography; Water Resources SC Meteorology & Atmospheric Sciences; Oceanography; Water Resources GA BV02Z UT WOS:000177651500044 ER PT B AU Bess, TD Wong, T Smith, GL Bush, KA AF Bess, TD Wong, T Smith, GL Bush, KA GP AMS AMS TI A fifteen year time series of longwave and shortwave radiation measurements for environmental and climate change studies SO 17TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 17th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 14-19, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc ID BUDGET EXPERIMENT; INSTRUMENT AB Fifteen years of monthly averaged wide field-of-view (WFOV) outgoing longwave radiation (OLR) and reflected shortwave radiation (RSW) numerical filter, 5 degree regional measurements from the Earth Radiation Budget Experiment (ERBE) are made available on the Internet/Web for use by the scientific community. This 15-year data set is from WFOV measurements taken by the dedicated Earth Radiation Budget Satellite (ERBS) which is in an orbit of 57 degree inclination and precesses through all local times in 72 days. The data set has been reprocessed to remove measurements in regions with poor temporal sampling. The data set spans the period from November 1984 through September 1999 and can be viewed and accessed using a web browser located on a server at NASA, Langley Research Center. The browser uses a live access server (LAS) developed by the Thermal Modeling and Analysis Project at NOAA's Pacific Marine Environmental Laboratory. LAS allows scientists to interact directly with the data to view, select, and subset the data in terms of month, year, latitude, and longitude. In addition to OLR and RSW measurements, statistics that result from calculating regional averages will be discussed. These statistics include shortwave and longwave standard deviation, and the number of measurements that go into each average. The problem of regions with no data will also be discussed. C1 NASA, Langley Res Ctr, Hampton, VA 23681 USA. RP Bess, TD (reprint author), NASA, Langley Res Ctr, MS 420, Hampton, VA 23681 USA. NR 9 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 275 EP 278 PG 4 WC Meteorology & Atmospheric Sciences; Oceanography; Water Resources SC Meteorology & Atmospheric Sciences; Oceanography; Water Resources GA BV02Z UT WOS:000177651500072 ER PT B AU Liu, Z Chiu, L Teng, W Serafino, G Yang, R Rui, H AF Liu, Z Chiu, L Teng, W Serafino, G Yang, R Rui, H GP AMS AMS TI An interactive hazard mapping system SO 17TH INTERNATIONAL CONFERENCE ON INTERACTIVE INFORMATION AND PROCESSING SYSTEMS (IIPS) FOR METEOROLOGY, OCEANOGRAPHY, AND HYDROLOGY LA English DT Proceedings Paper CT 17th International Conference on Interactive Information and Processing Systems (IIPS) for Meteorology, Oceanography and Hydrology CY JAN 14-19, 2001 CL ALBUQUERQUE, NM SP Amer Meteorol Soc C1 NASA, GSFC, GMU, DAAC, Greenbelt, MD 20771 USA. RP Liu, Z (reprint author), NASA, GSFC, GMU, DAAC, Code 902, Greenbelt, MD 20771 USA. NR 2 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 465 EP 467 PG 3 WC Meteorology & Atmospheric Sciences; Oceanography; Water Resources SC Meteorology & Atmospheric Sciences; Oceanography; Water Resources GA BV02Z UT WOS:000177651500125 ER PT S AU Meador, MA Meador, MAB Petkovsek, J Oliver, T Scheiman, DA Gariepy, C Nguyen, BC Eby, RK AF Meador, MA Meador, MAB Petkovsek, J Oliver, T Scheiman, DA Gariepy, C Nguyen, BC Eby, RK BE Repecka, L Saremi, FF TI PMR polyimides with enhanced melt flow for high temperature applications SO 2001: A MATERIALS AND PROCESSES ODYSSEY, BOOKS 1 AND 2 SE INTERNATIONAL SAMPE TECHNICAL CONFERENCE SERIES LA English DT Proceedings Paper CT 46th International SAMPE Symposium and Exhibition CY MAY 06-10, 2001 CL LONG BEACH, CA SP Soc Advancement Mat & Process Engn AB The development of RTM and RFI processable high temperature polymers has been the subject of intense research activity. Two approaches that we have been pursuing involve modification of the polyimide backbone through the introduction of (1) twisted biaryl moieties and (2) branching. In this paper, we review our findings in impoving manufacturing of these materials utilizing two approaches, present mechanical properties of carbon fiber reinforced composites prepared from resins utilizing each approach, and discuss more recent results that combine both approaches to give polyimides with superior melt flow and good high temperature performance. C1 NASA, Glenn Res Ctr, Div Mat, Cleveland, OH 44135 USA. RP Meador, MA (reprint author), NASA, Glenn Res Ctr, Div Mat, Cleveland, OH 44135 USA. OI Meador, Mary Ann/0000-0003-2513-7372 NR 11 TC 0 Z9 0 U1 1 U2 2 PU SOC ADVANCEMENT MATERIAL & PROCESS ENGINEERING PI COVINA PA 1161 PARKVIEW DR,, COVINA, CA 91724-3748 USA SN 0892-2624 BN 0-938994-90-5 J9 INT SAMPE TECH CONF PY 2001 VL 46 BP 497 EP 509 PG 3 WC Engineering, Chemical; Materials Science, Characterization & Testing; Materials Science, Composites SC Engineering; Materials Science GA BS96V UT WOS:000171526800045 ER EF