FN Thomson Reuters Web of Science™ VR 1.0 PT J AU NACHTIGAL, NM REICHEL, L TREFETHEN, LN AF NACHTIGAL, NM REICHEL, L TREFETHEN, LN TI A HYBRID GMRES ALGORITHM FOR NONSYMMETRIC LINEAR-SYSTEMS SO SIAM JOURNAL ON MATRIX ANALYSIS AND APPLICATIONS LA English DT Article DE ITERATIVE METHOD; KRYLOV SUBSPACE; CGNR; GMRES; CGS; HYBRID; PSEUDOSPECTRUM ID RICHARDSON ITERATION METHOD; SPECTRAL METHODS; POLYNOMIALS; EQUATIONS AB A new hybrid iterative algorithm is proposed for solving large nonsymmetric systems of linear equations. Unlike other hybrid algorithms, which first estimate eigenvalues and then apply this knowledge in further iterations, this algorithm avoids eigenvalue estimates. Instead, it runs GMRES until the residual norm drops by a certain factor, then re-applies the polynomial implicitly constructed by GMRES via a Richardson iteration with Leja ordering. Preliminary experiments suggest that the new algorithm frequently outperforms the restarted GMRES algorithm. C1 KENT STATE UNIV,DEPT MATH & COMP SCI,KENT,OH 44242. CORNELL UNIV,DEPT COMP SCI,ITHACA,NY 14853. RP NACHTIGAL, NM (reprint author), NASA,AMES RES CTR,ADV COMP SCI RES INST,MAIL STOP T041-5,MOFFETT FIELD,CA 94035, USA. NR 43 TC 79 Z9 81 U1 0 U2 3 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 0895-4798 J9 SIAM J MATRIX ANAL A JI SIAM J. Matrix Anal. Appl. PD JUL PY 1992 VL 13 IS 3 BP 796 EP 825 DI 10.1137/0613050 PG 30 WC Mathematics, Applied SC Mathematics GA HZ289 UT WOS:A1992HZ28900009 ER PT J AU WILSON, RM AF WILSON, RM TI AN EARLY ESTIMATE FOR THE SIZE OF CYCLE-23 SO SOLAR PHYSICS LA English DT Article ID SOLAR-ACTIVITY CYCLE; SUNSPOT NUMBER; PARTICLES; GROWTH AB Two features are found in the modern era sunspot record (cycles 10-22: ca. 1850-present) that may prove useful for gauging the size of cycle 23, the next sunspot cycle, several years ahead of its actual onset. These features include an inferred tong-term increase against time of maximum amplitude (RM, the maximum value of smoothed sunspot number for a cycle) and the apparently inherent differing natures of even- and odd-numbered sunspot cycles, especially when grouped consecutively as 'even-odd' cycle pairs. Concerning the first feature, one finds that 6 out of the last 6 sunspot cycles have had RM greater-than-or-equal-to 110.6 (the median value for the modern era record) and that 4 out of 6 have had RM > 150. Presuming this trend to continue, one anticipates that cycle 23 will likewise have RM greater-than-or-equal-to 110.6 and, perhaps, RM > 150. Concerning the second feature. one finds that, when one groups sunspot cycles into consecutively paired even-odd cycles. the odd-following cycle has always been the larger cycle, 6 out of 6 times. Because cycle 22 had RM = 158.5, one anticipates that cycle 23 will have RM > 158.5. Additionally, because he average 'difference' between RM(odd) and RM(even) for consecutively paired even-odd cycles is 40.3 units (sd = 14.2), one expects cycle 23 to have RM greater-than-or-equal-to 162.3 (RM = 198.8 + 36.5 at the 95% level of confidence). Further, because of the rather strong linear correlation (r = 0.959, se = 13.5) found between RM(odd) and RM(even) for consecutively paired even-odd cycles, one infers that cycle 23 should have RM greater-than-or-equal-to 176.4 (RM = 213.9 +/- 37.5 at the 95% level of confidence). Since large values of RM tend to be associated with fast rising cycles of short ascent duration and high levels of 10.7-cm solar radio flux, cycle 23 is envisioned to be potentially one of the greatest cycles of the modern era, if not the greatest. RP WILSON, RM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES52,HUNTSVILLE,AL 35812, USA. NR 34 TC 56 Z9 57 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD JUL PY 1992 VL 140 IS 1 BP 181 EP 193 DI 10.1007/BF00148438 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JD637 UT WOS:A1992JD63700014 ER PT J AU KIM, Q SCHWARTZ, HR EDMONDS, LD ZOUTENDYK, JA AF KIM, Q SCHWARTZ, HR EDMONDS, LD ZOUTENDYK, JA TI DIAGNOSIS OF NMOS DRAM FUNCTIONAL PERFORMANCE AS AFFECTED BY A PICOSECOND DYE-LASER SO SOLID-STATE ELECTRONICS LA English DT Article ID SINGLE EVENT UPSETS; ION TRACKS; INTEGRATED-CIRCUITS AB A picosecond pulsed dye laser beam was at selected wavelengths successfully used to simulate heavy-ion single-event effects (SEEs) in negative channel metal-oxide semiconductor dynamic random access memories (NMOS DRAMs). A DRAM was used to develop the test technique because bit-mapping capability and previous heavy-ion upset data were available. Other investigators have used Nd:Yag lasers to correlate laser and heavy-ion data for devices characterized by prompt charge collection, which is controlled by charge carrier density in the immediate vicinity of a depletion region. However, the present analysis is the first to establish such a correlation for devices, such as the NMOS DRAM, where charge collection is dominated by long-range diffusion, which is controlled by carrier density at remote distances from a depletion region. In the latter case, penetration depth is an important parameter and is included in the present analysis. A single-pulse picosecond dye laser beam (1.5-mu-m dia.) focused onto a single cell component can upset a single memory cell. In addition, clusters of memory cell upsets (multiple errors) were observed when the laser energy was increased above the threshold energy. The multiple errors were analyzed as a function of the bias voltage and total energy of a single pulse. A diffusion model to distinguish the multiple upsets from the laser-induced charge agreed well with previously reported heavy ion data. This correlation is one more step toward the goal of using a picosecond dye laser for SEE investigations. RP KIM, Q (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 11 TC 2 Z9 2 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0038-1101 J9 SOLID STATE ELECTRON JI Solid-State Electron. PD JUL PY 1992 VL 35 IS 7 BP 905 EP 912 DI 10.1016/0038-1101(92)90317-6 PG 8 WC Engineering, Electrical & Electronic; Physics, Applied; Physics, Condensed Matter SC Engineering; Physics GA JB924 UT WOS:A1992JB92400004 ER PT J AU WILLIAMS, RM JEFFRIESNAKAMURA, B UNDERWOOD, ML RYAN, MA OCONNOR, D KIKKERT, S AF WILLIAMS, RM JEFFRIESNAKAMURA, B UNDERWOOD, ML RYAN, MA OCONNOR, D KIKKERT, S TI HIGH-TEMPERATURE CONDUCTIVITY OF POTASSIUM-BETA''-ALUMINA SO SOLID STATE IONICS LA English DT Article ID INTERFACIAL IMPEDANCE; IONIC-CONDUCTIVITY; AMTEC ELECTRODES; BETA''-ALUMINA; TRANSPORT; KINETICS; ALUMINA; BETA; NA+; K+ AB Potassium beta"-alumina single crystals have been reported by several groups to have higher ionic conductivity than sodium beta"-alumina crystals at room temperature, and similar conductivities are obtained at temperatures up to 600-700 K. Potassium beta"-alumina ceramics have been reported to have significantly poorer conductivities than those of sodium beta"-alumina ceramics, but conductivity measurements at temperatures above 625 K have not been reported. In this study, K+-beta"-alumina ceramics were prepared from Na+-beta"-alumina ceramic using a modified version of the exchange reaction with KCl vapor reported by Crosbie and Tennenhouse, and the conductivity has been measured in K vapor at temperatures up to 1223 K, using the method of Cole, Weber and Hunt. The results indicate reasonable agreement with earlier data on K+-beta"-alumina ceramic measured in a liquid K cell, but show that the K+-beta"-alumina ceramic's conductivity approaches that of Na+-beta"-alumina ceramic at higher temperatures, being within a factor of four at 700 K and 60% of the conductivity of Na+-beta"-alumina at T > 1000 K. Both four-probe dc conductivity and four probe ac impedance measurements were used to characterize the conductivity. A rather abrupt change in the grain boundary resistance suggesting a possible phase change in the intergranular material, potassium aluminate, is seen in the ac impedance behavior. RP WILLIAMS, RM (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 15 TC 6 Z9 6 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-2738 J9 SOLID STATE IONICS JI Solid State Ion. PD JUL-AUG PY 1992 VL 53 BP 806 EP 810 DI 10.1016/0167-2738(92)90258-Q PN 2 PG 5 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA JP972 UT WOS:A1992JP97200015 ER PT J AU ERIKSON, EF AF ERIKSON, EF TI SOFIA - STRATOSPHERIC OBSERVATORY FOR INFRARED ASTRONOMY SO SPACE SCIENCE REVIEWS LA English DT Review RP ERIKSON, EF (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 2 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD JUL PY 1992 VL 61 IS 1-2 BP 61 EP 68 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JT304 UT WOS:A1992JT30400008 ER PT J AU ERICKSON, EF WERNER, MW AF ERICKSON, EF WERNER, MW TI SIRTF - SPACE INFRARED TELESCOPE FACILITY SO SPACE SCIENCE REVIEWS LA English DT Review RP ERICKSON, EF (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 1 TC 5 Z9 5 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD JUL PY 1992 VL 61 IS 1-2 BP 95 EP 98 DI 10.1007/BF00212477 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JT304 UT WOS:A1992JT30400010 ER PT J AU KAPLAN, M AF KAPLAN, M TI NASA FUTURE-PLANS FOR SPACE ASTRONOMY AND ASTROPHYSICS SO SPACE SCIENCE REVIEWS LA English DT Review RP KAPLAN, M (reprint author), NASA,DIV ASTROPHYS,ADV PROGRAMS BRANCH,OFF SPACE SCI & APPLICAT,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD JUL PY 1992 VL 61 IS 1-2 BP 103 EP 112 DI 10.1007/BF00212479 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JT304 UT WOS:A1992JT30400012 ER PT J AU HAWARDEN, TG CUMMINGS, RO TELESCO, CM THRONSON, HA AF HAWARDEN, TG CUMMINGS, RO TELESCO, CM THRONSON, HA TI OPTIMIZED RADIATIVE COOLING OF INFRARED SPACE TELESCOPES AND APPLICATIONS TO POSSIBLE MISSIONS SO SPACE SCIENCE REVIEWS LA English DT Review AB General principles are outlined for the design of space infrared telescopes intended to cool by radiation to the lowest temperatures attainable without the use of on-board cryogens, and assuming on-orbit cooling after a warm launch. Maximum protection from solar and earth heating, maximum radiating area and efficiency and minimum absorbing area and absorptivity are the obvious basic criteria. The optimised design is a short, fat telescope surrounded by a series of radiation shields, each cooled by its own radiator. Maximising the longitudinal conductivity of the radiation shields and of the telescope tube itself is important both to the on-orbit cooling time and the final achieveable temperature. Realistic designs take between 80 and 200 days to cool to within a few degrees of equilibrium temperatures, depending on the materials used. Great advantages accrue from the use of an orbit distant from earth. Both simple models and detailed simulations suggest that temperatures of 30 to 40 K are attainable in high earth orbits. Placing a radiatively cooled telescope in a halo orbit around the Lagrangian point L2 is a particularly attractive option and significantly lower temperatures can be achieved there than in Earth orbit. Optimised radiative cooling is an important element of the small Japanese mission SMIRT. We suggest that a combination of an ESA Medium-sized Mission with a NASA Explorer to send a 2m+ telescope to an L2 halo orbit would provide a cost-effective and powerful long-duration facility for the early 21st century. C1 ROYAL OBSERV,EDINBURGH EH9 3HJ,MIDLOTHIAN,SCOTLAND. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV WYOMING,WYOMING INFRARED OBSERV,LARAMIE,WY 82071. RP HAWARDEN, TG (reprint author), JOINT ASTRON CTR,665 KOMOHANA ST,HILO,HI 96720, USA. RI Thronson, Harley/E-3382-2012 NR 16 TC 12 Z9 12 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD JUL PY 1992 VL 61 IS 1-2 BP 113 EP 144 DI 10.1007/BF00212480 PG 32 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JT304 UT WOS:A1992JT30400013 ER PT J AU DURRANI, SH PERKINS, DC CARLTON, PD AF DURRANI, SH PERKINS, DC CARLTON, PD TI EXPERT SYSTEMS AND ADVANCED AUTOMATION FOR SPACE MISSIONS OPERATIONS SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article; Proceedings Paper CT 41ST CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 06-12, 1990 CL DRESDEN, GERMANY SP INT ASTRONAUT FEDERAT AB Increased complexity of space missions during the 1980s led to the introduction of expert systems and advanced automation techniques in mission operations. This paper describes several technologies in operational use or under development at the National Aeronautics and Space Administration's Goddard Space Flight Center. Several expert systems are described that diagnose faults, analyze spacecraft operations and onboard subsystem performance (in conjunction with neural networks), and perform data quality and data accounting functions. The design of customized user interfaces is discussed. with examples of their application to pace missions. Displays, which allow mission operators to see the spacecraft position, orientation, and configuration under a variety of operating conditions, are described. Automated systems for scheduling are discussed, and a test bed that allows tests and demonstrations of the associated architectures, interface protocols, and operations concepts is described. Lessons learned are summarized. RP DURRANI, SH (reprint author), NASA,OFF SPACE OPERAT,CODE OP,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD JUL PY 1992 VL 12 IS 3 BP 293 EP 304 PG 12 WC Engineering, Aerospace SC Engineering GA JC990 UT WOS:A1992JC99000005 ER PT J AU FREEMAN, DC POWELL, RW BRAUN, RD AF FREEMAN, DC POWELL, RW BRAUN, RD TI MANNED MARS AEROBRAKE VEHICLE DESIGN ISSUES SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article; Proceedings Paper CT 41ST CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 06-12, 1990 CL DRESDEN, GERMANY SP INT ASTRONAUT FEDERAT AB In the design of a high-energy aerobraking vehicle to support a manned Mars mission, several significant vehicle-dependent issues must be addressed. This investigation focuses on the preliminary definition of the stagnation region acrothermodynamic environment (both convective and radiative), effect of trim angle-of-attack mispredictions, packaging issues, and the implications of wake flow for those vehicles without an aft aeroshell. This study assesses the implications of each of these factors for a Mars aerobrake configuration with a lift drag ratio (L/D) in the range of 0.3-0.5. The objective of this study is not to design an optimal, final vehicle, but rather to understand the implications and requirements of each issue on a typical class of aerobrake design concepts. These analyses show that packaging and wake flow requirements have a significant impact on the final design of a low L/D aerobrake. In particular, if an aerobrake with an L/D of 0.5 is required, a transportation system which includes more than one aerobrake is probably warranted. A trim angle of attack error of 5-degrees is also evaluated. This error, which could potentially cause a loss of the vehicle, must be accommodated in the design of the onboard guidance algorithm and the determination of an allowable payload packaging volume. Additionally, because the large proportion of carbonaceous species in the Martian atmosphere, radiative heating is shown to play a more dominant role in the stagnation region aerothermodynamics than for an equivalent Earth entry. The effects of radiation are amplified by the use of a large diameter Mars aerobrake in support of a manned mission; this radiation amplification is an additional reason to consider a multiple aerobrake system. RP FREEMAN, DC (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 3 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD JUL PY 1992 VL 12 IS 3 BP 313 EP 324 PG 12 WC Engineering, Aerospace SC Engineering GA JC990 UT WOS:A1992JC99000007 ER PT J AU TO, HY VALCO, GJ BHASIN, KB AF TO, HY VALCO, GJ BHASIN, KB TI 10 GHZ YBA2CU3O7-DELTA SUPERCONDUCTING RING RESONATORS ON NDGAO3 SUBSTRATES SO SUPERCONDUCTOR SCIENCE & TECHNOLOGY LA English DT Article ID THIN-FILMS; BA2YCU3O7-DELTA FILMS; LASER ABLATION; LAALO3 AB YBa2Cu3O7-delta thin films were formed on NdGaO3 substrates by laser ablation. Critical temperatures greater than 89 K and critical current densities exceeding 2 x 10(6) A cm-2 at 77 K were obtained. The microwave performance of films patterned into microstrip ring resonators with gold ground planes was measured. An unloaded quality factor six times larger than a that of a gold resonator of identical geometry was achieved. The unloaded quality factor decreased below 70 K for both the superconducting and gold resonators due to increasing dielectric losses in the substrate. The temperature dependence of the loss tangent of NdGaO3 Was extracted from the measurements. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP TO, HY (reprint author), OHIO STATE UNIV,DEPT ELECT ENGN,COLUMBUS,OH 43210, USA. NR 19 TC 8 Z9 8 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-2048 J9 SUPERCOND SCI TECH JI Supercond. Sci. Technol. PD JUL PY 1992 VL 5 IS 7 BP 421 EP 426 DI 10.1088/0953-2048/5/7/002 PG 6 WC Physics, Applied; Physics, Condensed Matter SC Physics GA JG352 UT WOS:A1992JG35200002 ER PT J AU MIRANDA, FA CHOREY, CM STAN, MA NORDGREN, CE KWOR, RY KALKUR, TS AF MIRANDA, FA CHOREY, CM STAN, MA NORDGREN, CE KWOR, RY KALKUR, TS TI MICROWAVE PROPERTIES AND CHARACTERIZATION OF COEVAPORATED BSCCO THIN-FILMS SO SUPERCONDUCTOR SCIENCE & TECHNOLOGY LA English DT Article ID WAVE COMPLEX-CONDUCTIVITY; CA-CU-O; EPITAXIAL YBA2CU3O7-SIGMA FILMS; MAGNETIC PENETRATION DEPTH; SURFACE-RESISTANCE; 40.0 GHZ; BI2SR2CACU2O8; GROWTH; RANGE AB An extensive characterization of Bi-Sr-Ca-Cu-O (BSCCO) thin films deposited by co-evaporation on LaAlO3 and SrTiO3 substrates has been performed. The films had a T(c)(R = 0) of approximately 78 K, and were predominantly c-axis oriented, with critical current densities (J(c)) at 4.5 K of 1.6 x 10(6) and 11 x 10(6) A cm-2, for the samples on SrTiO3 and LaAlO3 respectively The microwave properties of the films were examined by three techniques. The complex conductivity (sigma* = sigma-1 - j-sigma-2) and the magnetic penetration depth (lambda) were measured by power transmission at 30.6 GHz; the surface resistance (R(s)) was measured using a cavity resonator at 58.9 GHz, and the transmission line losses were determined by measuring the quality factor (0) of a linear microstrip resonator at 10.4 and 20.2 GHz. The complex conductivity for the film on LaAlO3 was determined to be (2.0 - j10) x 10(5) S m-1 at 77 K. It was observed that in the superconducting state sigma-1 deviates from both the Bardeen-Cooper-Schrieffer (BCS) theory and the two-fluid model. ValueS Of lambda were found to be approximately 2.0 and 1.1-mu-m at 77 K and 20 K respectively, and were obtained for the film on LaAlO3. The value of lambda at 20 K was approximately three times larger than that ot BSCCO single crystals. R(s) values of 865 and 1391 m-OMEGA were obtained for the films on SrTiO3 and LaAlO3, respectively, at 77 K and 58.9 GHz Unloaded Q factors at 20 K of approximately 1100 and 800 at 10 4 and 20.2 GHz respectively, were measured for the BSCCO resonator. Unloaded Q values of 290 and 405 at 20 K were obtained at 10.4 GHz and 20.2 GHz respectively for an all gold (Au) resonator. C1 SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,BROOK PK,OH 44142. KENT STATE UNIV,DEPT PHYS,KENT,OH 44242. CASE WESTERN RESERVE UNIV,DEPT PHYS,CLEVELAND,OH 44106. UNIV COLORADO,DEPT ELECT & COMP ENGN,COLORADO SPRINGS,CO 80933. RP MIRANDA, FA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 34 TC 2 Z9 2 U1 1 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-2048 J9 SUPERCOND SCI TECH JI Supercond. Sci. Technol. PD JUL PY 1992 VL 5 IS 7 BP 453 EP 460 DI 10.1088/0953-2048/5/7/009 PG 8 WC Physics, Applied; Physics, Condensed Matter SC Physics GA JG352 UT WOS:A1992JG35200009 ER PT J AU LEE, TJ RENDELL, AP TAYLOR, PR AF LEE, TJ RENDELL, AP TAYLOR, PR TI THE STRUCTURES, BINDING-ENERGIES AND VIBRATIONAL FREQUENCIES OF CA3 AND CA4 - AN APPLICATION OF THE CCSD(T) METHOD SO THEORETICA CHIMICA ACTA LA English DT Article; Proceedings Paper CT INTERNATIONAL SYMP ON AB INITIO METHODS IN QUANTUM CHEMISTRY CY MAY 10, 1991 CL AMES, IA DE CA3/CA4 METALLIC CLUSTERS; CCSD(T) METHOD; VIBRATIONAL FREQUENCIES ID CONFIGURATION-INTERACTION; METAL-CLUSTERS; BASIS-SETS; SPECTROSCOPY; MOLECULES; SPECTRA; 1ST-ROW; TRIPLE; BEAMS; ATOMS AB The Ca3 and Ca4 metallic clusters have been investigated using state-of-the-art ah initio quantum mechanical methods. Large atomic natural orbital basis sets have been used in conjunction with the singles and doubles coupled-cluster (CCSD) method, a coupled-cluster method that includes a perturbational estimate of connected triple excitations, denoted CCSD(T), and the multireference configuration interaction (MRCI) method. The equilibrium geometries, binding energies and harmonic vibrational frequencies have been determined with each of the methods so that the accuracy of the coupled-cluster methods may be assessed. Since the CCSD(T) method reproduces the MRCI results very well, cubic and quartic force fields of Ca3 and Ca4 have been determined using this approach and used to evaluate the fundamental vibrational frequencies. The infrared intensities of both the e' mode of Ca3 and the t2 mode of Ca4 are found to be small. The results obtained in this study are compared and contrasted with those from our earlier studies on small Be and Mg clusters. C1 ELORET INST,PALO ALTO,CA 94303. RP LEE, TJ (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Rendell, Alistair/A-4883-2008; Lee, Timothy/K-2838-2012 OI Rendell, Alistair/0000-0002-9445-0146; NR 29 TC 16 Z9 16 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0040-5744 J9 THEOR CHIM ACTA JI Theor. Chim. Acta PD JUL PY 1992 VL 83 IS 1-2 BP 165 EP 175 DI 10.1007/BF01113249 PG 11 WC Chemistry, Physical SC Chemistry GA JF164 UT WOS:A1992JF16400012 ER PT J AU OLLA, BL DAVIS, MW SCHRECK, CB AF OLLA, BL DAVIS, MW SCHRECK, CB TI COMPARISON OF PREDATOR AVOIDANCE CAPABILITIES WITH CORTICOSTEROID LEVELS INDUCED BY STRESS IN JUVENILE COHO SALMON SO TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY LA English DT Note ID ONCORHYNCHUS-KISUTCH SMOLTS; FUNDULUS-HETEROCLITUS; CHINOOK SALMON; CORTISOL; TRANSPORTATION; RESPONSES; SEAWATER; PLASMA AB The relationship between predator avoidance deficits induced by a simple handling stress and the level of plasma corticosteroids was determined for juvenile coho salmon Oncorhynchus kisutch. Groups of fish were held out of water for 1 min, then allowed to recover from this stress for 1, 90, or 240 min. After each recovery period, some unstressed and stressed fish were sampled for plasma cortisol, and others were subjected to predation by lingcod Ophiodon elongatus. Levels of corticosteroids in stressed fish remained high throughout the 240-min period of recovery, but predator avoidance returned to control levels in less than 90 min. Results suggest that juvenile coho salmon quickly recover basic survival skills of predator avoidance after mild stress, even though cortisol levels continue to indicate a stressed condition. C1 OREGON STATE UNIV,OREGON COOPERAT FISHERY RES UNIT,US FISH & WILDLIFE SERV,CORVALLIS,OR 97331. RP OLLA, BL (reprint author), HATFIELD MARINE SCI CTR,NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,NEWPORT,OR 97365, USA. NR 19 TC 59 Z9 59 U1 1 U2 14 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 SN 0002-8487 J9 T AM FISH SOC JI Trans. Am. Fish. Soc. PD JUL PY 1992 VL 121 IS 4 BP 544 EP 547 DI 10.1577/1548-8659(1992)121<0544:NCOPAC>2.3.CO;2 PG 4 WC Fisheries SC Fisheries GA JZ974 UT WOS:A1992JZ97400012 ER PT J AU MEHTA, NP RATTAN, SS VERMA, A DIMOFTE, F AF MEHTA, NP RATTAN, SS VERMA, A DIMOFTE, F TI COMBINED EFFECT OF TURBULENCE, LOAD ORIENTATION AND ROTOR FLEXIBILITY ON THE PERFORMANCE OF 3-LOBE BEARINGS SO TRIBOLOGY TRANSACTIONS LA English DT Article AB A three-lobe journal bearing is analytically investigated to determine its dynamic performance when three main parameters, i.e. turbulence, load orientation, and rotor flexibility are varied. Reynolds numbers up to 12000, rotor dimensionless flexibilities up to 4, and load orientations up to 30 degrees on either side of the vertical load line are considered. Thus, almost all cases of practical interest are studied. The stability of a three-lobe bearing improves due to turbulence at high Sommerfeld numbers (more than 0.6)for a rigid rotor, while it is virtually the same for flexible rotors. Conversely, the load orientation has a pronounced effect on stability for both rigid and flexible rotors. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44125. RP MEHTA, NP (reprint author), REG ENGN COLL,DEPT MECH ENGN,KURUKSHETRA 132119,HARYANA,INDIA. NR 19 TC 2 Z9 2 U1 1 U2 2 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0569-8197 J9 TRIBOL T JI Tribol. Trans. PD JUL PY 1992 VL 35 IS 3 BP 530 EP 536 DI 10.1080/10402009208982152 PG 7 WC Engineering, Mechanical SC Engineering GA JC073 UT WOS:A1992JC07300020 ER PT J AU BOZZOLO, G FERRANTE, J AF BOZZOLO, G FERRANTE, J TI THEORETICAL MODELING OF AFM FOR BIMETALLIC TIP SUBSTRATE INTERACTIONS SO ULTRAMICROSCOPY LA English DT Article; Proceedings Paper CT 6TH INTERNATIONAL CONF ON SCANNING TUNNELING MICROSCOPY ( STM 91 ) CY AUG 12-16, 1991 CL INTERLAKEN, SWITZERLAND SP BOARD SWISS FED INST TECHNOL, DAIMLER BENZ FONDS, IBM RES DIV, ZURICH RES LAB, IBM SWITZERLAND, SWISS NATL SCI FDN, CIBA GEIGY, HOFFMANN LA ROCHE, LONZA, SANDOZ, FDN ERNST & LUCIE SCHMIDHEINY ID ATOMIC-FORCE-MICROSCOPE; EQUIVALENT-CRYSTAL THEORY; ADHESION; SURFACES; IMAGES; DEFECTS; METAL AB Recently, a new technique for calculating the defect energetics of alloys based on equivalent crystal theory has been developed. This new technique successfully predicts the bulk properties for binary alloys as well as segregation energies in the dilute limit. We apply this method for the calculation of energy and force as a function of separation of an AFM tip and substrate. This study was done for different combinations of tip and sample materials. The validity of the universality discovered for same metal interfaces is examined for the case of different metal interactions. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BOZZOLO, G (reprint author), ANALEX CORP,3001 AEROSP PKWY,BROOK PK,OH 44142, USA. NR 16 TC 15 Z9 15 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0304-3991 J9 ULTRAMICROSCOPY JI Ultramicroscopy PD JUL PY 1992 VL 42 BP 55 EP 58 DI 10.1016/0304-3991(92)90245-F PN A PG 4 WC Microscopy SC Microscopy GA JL737 UT WOS:A1992JL73700009 ER PT J AU HITCHCOCK, HD AF HITCHCOCK, HD TI 1ST PACIFIC INTERNATIONAL-CONGRESS ON X-RAY ANALYTICAL METHODS (PICXAM) SO X-RAY SPECTROMETRY LA English DT Editorial Material RP HITCHCOCK, HD (reprint author), NASA,KENNEDY SPACE CTR,FL 32815, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0049-8246 J9 X-RAY SPECTROM JI X-Ray Spectrom. PD JUL-AUG PY 1992 VL 21 IS 4 BP 204 EP 204 DI 10.1002/xrs.1300210413 PG 1 WC Spectroscopy SC Spectroscopy GA JJ776 UT WOS:A1992JJ77600010 ER PT J AU THAKOOR, S AF THAKOOR, S TI HIGH-SPEED, NONDESTRUCTIVE READOUT FROM THIN-FILM FERROELECTRIC MEMORY SO APPLIED PHYSICS LETTERS LA English DT Article AB High speed, polarization direction dependent photoresponse from ferroelectric lead zirconate titanate (PbZr0.53Ti0.47O3) thin films, sandwiched between conducting electrodes to form a memory capacitor, is reported. Laser pulses with a full width at half maximum of approximately 10 ns at 532 nm wavelength are utilized to readout the photoresponse signal from individual polarized elements. Such readout is repeated over a million times, with no detectable degradation in the photoresponse or the remanent polarization, suggesting its potential as a nondestructive readout (NDRO) of nonvolatile polarization state in thin-film ferroelectric memories. In principle, both electronic as well as thermal mechanisms could be triggered by such photon exposure of ferroelectric thin films. A comparison of the photoresponse from capacitors with semitransparent and opaque top electrodes suggests that the observed NDRO signal is primarily due to thermally triggered mechanisms. RP THAKOOR, S (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 15 TC 31 Z9 31 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUN 29 PY 1992 VL 60 IS 26 BP 3319 EP 3321 DI 10.1063/1.106679 PG 3 WC Physics, Applied SC Physics GA JA806 UT WOS:A1992JA80600040 ER PT J AU ZAHNLE, KJ AF ZAHNLE, KJ TI AIRBURST ORIGIN OF DARK SHADOWS ON VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID IMPACT CRATERS; TUNGUSKA EVENT; VENERA-15; DYNAMICS AB A simple analytic model for the catastrophic disruption and deceleration of impactors in a thick atmosphere is used to (1) reproduce observed Venusian cratering statistics and (2) generate radar-dark disks by the impact of atmospheric shock waves with the surface. When used as input to Monte Carlo simulations of Venusian cratering, the model nicely reproduces the observed low diameter cutoff. Venusian craters are found to be more consistent with an asteroidal rather than a cometary source. The radar-dark ''shadows'' of the title are surface features, usually circular, that have been attributed to airbursting impactors. A typical craterless airburst is the equivalent of a approximately 10(6) megaton explosion. The airburst is treated as a massive, extended explosion using a thin-shell, isobaric cavity approximation. The strong atmospheric shock waves excited by the airburst are then coupled to surface rock using the usual impedance matching conditions. Peak shock pressures experienced by surface rock typically exceed 0.2 GPa for distances 15-30 km from ground zero (the place on the surface immediately beneath the site of the airburst), and 1 GPa for 10-20 km. These high shock pressures are felt to considerable depth, often more than a kilometer. Beneath the airburst the shock could reduce surface rocks to fine rubble, while at greater distance the weaker shock would leave fields of broken blocks, perhaps in part accounting for radar-bright halos that often surround the dark shadows. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 33 TC 76 Z9 76 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUN 25 PY 1992 VL 97 IS E6 BP 10243 EP 10255 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU050 UT WOS:A1992KU05000004 PM 11538404 ER PT J AU MORRIS, RV SCHULZE, DG LAUER, HV AGRESTI, DG SHELFER, TD AF MORRIS, RV SCHULZE, DG LAUER, HV AGRESTI, DG SHELFER, TD TI REFLECTIVITY (VISIBLE AND NEAR IR), MOSSBAUER, STATIC MAGNETIC, AND X-RAY-DIFFRACTION PROPERTIES OF ALUMINUM-SUBSTITUTED HEMATITES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID A1-SUBSTITUTED HEMATITES; MORIN TRANSITION; A1 SUBSTITUTION; OXIDES; SPECTROSCOPY; GOETHITES; MARS; AL; DIMENSIONS; MIXTURES AB Because aluminum substitution for iron occurs in polymorphs of Fe2O3 and FeOOH in terrestrial (and by inference Martian) environments, it is important for the mineralogical remote sensing of both planets at visible and near-IR wavelengths to know the effects of Al substitution on their reflectivity spectra. Diffuse reflectivity (350-2200 mn), Mossbauer, static magnetic, and X ray diffraction data are reported for a series of aluminum-substituted hematites alpha-(Fe,Al)2O3 for compositions having values of Al(s) (mole ratio Al/(Al+Fe)) up to 0.61. Samples were prepared by oxidation of magnetite, dehydroxylation of goethite, and direct precipitation. Unit cell dimensions decrease with Al(s) but at a rate less than that predicted by the Vegard rule. At 293 K, Mossbauer spectra am sextets (negative quadrupole splitting, QS) for Al(s) up to approximately 0.5 and doublets for larger Al(s). At 21 K, all compositions are sextets; however, there is a discontinuity of approximately 0.5 T in the magnetic hyperfine field (B(hf)) and QS changes sign at Al(s) = 0.06(2) (Morin transition). Al-poor compositions have positive QS and higher B(hf). Negative and positive quadrupole splittings are indicative of the weakly ferromagnetic and antiferromagnetic states of hematites, respectively. The position of the least energetic crystal-field transition (6A1 --> 4T1g) of ferric iron shifts to longer wavelengths with increasing Al(s). The magnitude of the shift is a linear function of (1/a)5, where a is the hexagonal unit cell dimension. For geologically reasonable amounts of Al substitution (Al(s) < 0.33), the magnitude of the shift is small (approximately 20 mn), so that it is problematical (based on reflectivity data alone) to uniquely ascribe shifts in 4T1g band positions to different degrees of Al substitution. On the basis of Martian spectral data, the range in Al(s) for Martian hematites is 0 < Al(s) < 0.19. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. PURDUE UNIV,DEPT AGRON,W LAFAYETTE,IN 47907. UNIV ALABAMA,DEPT PHYS,BIRMINGHAM,AL 35294. NR 44 TC 16 Z9 16 U1 3 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUN 25 PY 1992 VL 97 IS E6 BP 10257 EP 10266 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU050 UT WOS:A1992KU05000005 ER PT J AU PARTRIDGE, H BAUSCHLICHER, CW LANGHOFF, SR AF PARTRIDGE, H BAUSCHLICHER, CW LANGHOFF, SR TI THEORETICAL-STUDY OF METAL-IONS BOUND TO HE, NE, AND AR SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID CORE VALENCE CORRELATION; GTO BASIS-SETS; 2ND-ROW ATOMS; RARE-GAS; 1ST-ROW; ENERGY AB The spectroscopic constants for the ground and selected low-lying electronic states of the transition metal-noble gas ions have been determined at the modified coupled-pair functional level of electron correlation treatment. There is a strong correlation between the binding energy and bond length, since the bonding is predominantly electrostatic (charge-induced dipole). In general, our calculated binding energies are about 20% less than the experimental values due to limitations in the level of theory used. The ions with an occupied s orbital (Mg+, Sc+, Ti+, Mn+, and Fe+) have much smaller binding energies than those that have a 3d(n+1) occupation. Those ions with an occupied metal valence s orbital are more weakly bound, because the small noble-gas polarizabilities do not lead to a sufficiently strong interaction to significantly polarize the metal s orbital. This leads to binding energies and bond lengths that follow the trends Ar > Ne > He and He > Ne > Ar, respectively. For the metal ions without an occupied valence s orbital, the binding energies involving Ar are largest, but whether MHe+ or MNe+ is more strongly bound depends on the details of the interaction. RP PARTRIDGE, H (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 32 TC 127 Z9 127 U1 3 U2 11 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUN 25 PY 1992 VL 96 IS 13 BP 5350 EP 5355 DI 10.1021/j100192a032 PG 6 WC Chemistry, Physical SC Chemistry GA JB264 UT WOS:A1992JB26400032 ER PT J AU HEIRTZLER, JR AF HEIRTZLER, JR TI FRONTIERS IN GEOMAGNETISM SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article ID MAGNETIC-FIELDS RP HEIRTZLER, JR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD JUN 23 PY 1992 VL 655 BP 77 EP 85 DI 10.1111/j.1749-6632.1992.tb17066.x PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JQ045 UT WOS:A1992JQ04500015 ER PT J AU HOLT, SS AF HOLT, SS TI NEW FRONTIERS IN X-RAY ASTRONOMICAL SPECTROSCOPY SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article RP HOLT, SS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE SCI,GREENBELT,MD 20771, USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD JUN 23 PY 1992 VL 655 BP 263 EP 277 DI 10.1111/j.1749-6632.1992.tb17076.x PG 15 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JQ045 UT WOS:A1992JQ04500025 ER PT J AU FISHMAN, GJ AF FISHMAN, GJ TI GAMMA-RAY OBSERVATIONS OF THE CRAB PULSAR - PAST, PRESENT, FUTURE SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Editorial Material RP FISHMAN, GJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 17 TC 1 Z9 1 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD JUN 23 PY 1992 VL 655 BP 309 EP 318 DI 10.1111/j.1749-6632.1992.tb17079.x PG 10 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JQ045 UT WOS:A1992JQ04500028 ER PT J AU RAMATY, R LINGENFELTER, RE AF RAMATY, R LINGENFELTER, RE TI GALACTIC POSITRON-ANNIHILATION RADIATION SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article ID GAMMA-RAY LINES; CENTER DIRECTION; CENTER REGION; MOLECULAR CLOUD; 1E1740.7-2942; CONTINUUM; EMISSION; AL-26 AB In what follows, we shall discuss recent developments in the study of galactic positron production and annihilation. The relevant observations are a series of measurements made with balloon and satellite-borne detectors and spanning over two decades in time. These data have provided evidence for a variable source of narrow 511 keV line emission at or near the Galactic Center. Of equal significance are recent observations carried out with the aid of an imaging gamma ray spectrometer that has detected localized sources of annihilation radiation. We shall consider the relationship between one of these sources, probably a black hole near the Galactic Center, and the narrow 511 keV line source. We shall also direct our attention to the diffuse component of the galactic 511 keV line emission. This component is probably due to positrons that result from the decay of radionuclei produced in various processes of galactic nucleosynthesis. C1 UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. RP RAMATY, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 40 TC 0 Z9 0 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD JUN 23 PY 1992 VL 655 BP 319 EP 325 DI 10.1111/j.1749-6632.1992.tb17080.x PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JQ045 UT WOS:A1992JQ04500029 ER PT J AU HAYMES, RC OPP, AG STACHNIK, RV AF HAYMES, RC OPP, AG STACHNIK, RV TI ASTROPHYSICS FROM THE LUNAR OUTPOST SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article AB In 1989, a study was conducted of the enhancement to the NASA astronomical program that would ensue if observations were conducted from a Lunar Outpost. This paper describes the strategy of the program, and summarizes the Lunar Outpost astronomical facilities and their scientific rationale. The strategy underlying the astronomical program calls for contemporaneous observations across the entire electromagnetic spectrum. To conduct them, suborbital programs, Explorers, Spacelab, and the Great Observatories are used, together with the unique, moon-based astronomical facilities. The moon offers a stable base for large systems, passive cooling, freedom from light pollution, and long baselines for interferometry. Large, filled-aperture radiation collectors have great sensitivity; long baseline interferometers have high angular resolution. The study concluded that addition of the evolutionary facilities studied for the Lunar Outpost would increase the sensitivity and angular resolution of the astronomical program by orders of magnitude. C1 BDM INT INC,WASHINGTON,DC 20024. NASA,DIV ASTROPHYS,WASHINGTON,DC 20546. RP HAYMES, RC (reprint author), RICE UNIV,DEPT SPACE PHYS & ASTRON,HOUSTON,TX 77251, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD JUN 23 PY 1992 VL 655 BP 326 EP 339 DI 10.1111/j.1749-6632.1992.tb17081.x PG 14 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JQ045 UT WOS:A1992JQ04500030 ER PT J AU SHEN, JY HUANG, JK TAYLOR, LW AF SHEN, JY HUANG, JK TAYLOR, LW TI LIKELIHOOD ESTIMATION FOR DISTRIBUTED PARAMETER MODELS OF LARGE BEAM-LIKE STRUCTURES SO JOURNAL OF SOUND AND VIBRATION LA English DT Article C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP SHEN, JY (reprint author), OLD DOMINION UNIV,NORFOLK,VA 23529, USA. NR 12 TC 3 Z9 3 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD JUN 22 PY 1992 VL 155 IS 3 BP 467 EP 480 DI 10.1016/0022-460X(92)90712-7 PG 14 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA JB339 UT WOS:A1992JB33900005 ER PT J AU PETERSON, BM ALLOIN, D AXON, D BALONEK, TJ BERTRAM, R BOROSON, TA CHRISTENSEN, JA CLEMENTS, SD DIETRICH, M ELVIS, M FILIPPENKO, AV GASKELL, CM HASWELL, CA HUCHRA, JP JACKSON, N KOLLATSCHNY, W KORISTA, KT LAME, NJ LEACOCK, RJ LIN, SN MALKAN, MA MONK, AS PENSTON, MV POGGE, RW ROBINSON, A ROSENBLATT, EI SHIELDS, JC SMITH, AG STIRPE, GM SUN, WH TURNER, TJ WAGNER, RM WILKES, BJ WILLS, BJ AF PETERSON, BM ALLOIN, D AXON, D BALONEK, TJ BERTRAM, R BOROSON, TA CHRISTENSEN, JA CLEMENTS, SD DIETRICH, M ELVIS, M FILIPPENKO, AV GASKELL, CM HASWELL, CA HUCHRA, JP JACKSON, N KOLLATSCHNY, W KORISTA, KT LAME, NJ LEACOCK, RJ LIN, SN MALKAN, MA MONK, AS PENSTON, MV POGGE, RW ROBINSON, A ROSENBLATT, EI SHIELDS, JC SMITH, AG STIRPE, GM SUN, WH TURNER, TJ WAGNER, RM WILKES, BJ WILLS, BJ TI STEPS TOWARD DETERMINATION OF THE SIZE AND STRUCTURE OF THE BROAD-LINE REGION IN ACTIVE GALACTIC NUCLEI .3. FURTHER OBSERVATIONS OF NGC-5548 AT OPTICAL WAVELENGTHS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-5548); GALAXIES, SEYFERT; QUASARS, EMISSION LINES ID SEYFERT-GALAXIES; QUASARS AB We report on thc results of the second year of an intensive ground-based spectroscopic and photometric study of variability in the bright Seyfert 1 galaxy NGC 5548, which has been undertaken in order to study the relationship between continuum and emission-line variability. Relative to the first year of the monitoring program, the nucleus of NGC 5548 was considerably fainter and the continuum variations slower during the second year, but the continuum-H-beta cross-correlation results for the two years are nearly identical. The variations in the broad H-beta emission line lag behind those in the continuum by somewhat less than 20 days, as concluded from the first year's data. C1 OBSERV PARIS,CNRS,URA 173,F-92195 MEUDON,FRANCE. COLGATE UNIV,DEPT PHYS & ASTRON,HAMILTON,NY 13346. KITT PEAK NATL OBSERV,NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. UNIV FLORIDA,DEPT ASTRON,GAINESVILLE,FL 32611. UNIV STERNWARTE GOTTINGEN,W-3400 GOTTINGEN,GERMANY. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. NATL CENT UNIV,INST PHYS & ASTRON,32054 CHUNGLI,TAIWAN. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. ROYAL GREENWICH OBSERV,CAMBRIDGE CB3 0EZ,ENGLAND. UNIV CAMBRIDGE,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. OSSERV ASTRON BOLOGNA,I-40126 BOLOGNA,ITALY. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP PETERSON, BM (reprint author), OHIO STATE UNIV,DEPT ASTRON,174 W 18TH AVE,COLUMBUS,OH 43210, USA. RI Stirpe, Giovanna/O-9393-2015 OI Stirpe, Giovanna/0000-0002-3702-8731 NR 13 TC 72 Z9 72 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP 470 EP 484 DI 10.1086/171447 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY145 UT WOS:A1992HY14500011 ER PT J AU KRISS, GA DAVIDSEN, AF BLAIR, WP BOWERS, CW DIXON, WV DURRANCE, ST FELDMAN, PD FERGUSON, HC HENRY, RC KIMBLE, RA KRUK, JW LONG, KS MOOS, HW VANCURA, O AF KRISS, GA DAVIDSEN, AF BLAIR, WP BOWERS, CW DIXON, WV DURRANCE, ST FELDMAN, PD FERGUSON, HC HENRY, RC KIMBLE, RA KRUK, JW LONG, KS MOOS, HW VANCURA, O TI HOPKINS ULTRAVIOLET TELESCOPE OBSERVATIONS OF THE FAR-ULTRAVIOLET SPECTRUM OF NGC-4151 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (GC-4151); GALAXIES, NUCLEI; GALAXIES, SEYFERT; ULTRAVIOLET, GALAXIES ID EMISSION-LINES; DETAILED OBSERVATIONS; SEYFERT-GALAXIES; QUASARS; IUE; VARIABILITY; EXTINCTION; NUCLEI AB We observed the far-ultraviolet spectrum of the Seyfert galaxy NGC 4151 from 912 to 1860 angstrom with the Hopkins Ultraviolet Telescope during the flight of Astro-1 aboard the space shuttle Columbia in 1990 December. Broad emission lines with full-width at half-maximum of approximately 8500 km s-1 dominate the spectrum. Numerous absorption features modify the continuum shape, particularly at wavelengths shortward of Ly-alpha. The continuum turns over sharply below 1000 angstrom and disappears by 924 angstrom, well above the redshifted Lyman edge of NGC 4151 at 915 angstrom. The continuum flux and the intensity of broad C IV lambda-1549 are slightly above the historical mean values observed with the International Ultraviolet Explorer. Many of the spectral features in the 912-1150 angstrom range have never before been seen in a low-redshift activity galaxy, including emission from O VI lambda-lambda-1032, 1037 and He II lambda-1085, and absorption by C III lambda-977, N III lambda-991, 0 VI lambda-lambda-1032, 1037, and the hydrogen Lyman series. The broad emission lines all have similar profiles, and their relative intensities are consistent with previously calculated photoionization models. The absorption lines have intrinsic widths of approximately 1000 km s-1 and are blueshifted relative to the systemic velocity of NGC 4151 by 200-1300 km s-1. The observed equivalent widths of the C III absorption lines lambda-977 and lambda-1176 require absorbing material with a density in excess of 10(9.5) cm-3. The equivalent widths of these same lines, the Si IV doublet lambda-lambda-1393, 1402, and the hydrogen Lyman lines all favor a Doppler parameter b congruent-to 200 km s-1 for the absorbing material. Absorption of the continuum by the converging higher order Lyrman lines explains the sharp turnover of the continuum below 1000 angstrom. The blueshifts of the absorption lines, their large intrinsic widths, and the. inferred high densities are all consistent with outflowing material originating in the broad-line region. C1 CAMBRIDGE UNIV OBSERV,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP KRISS, GA (reprint author), JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,CTR ASTROPHYS SCI,BALTIMORE,MD 21218, USA. RI Kimble, Randy/D-5317-2012; Kruk, Jeffrey/G-4047-2012 NR 28 TC 81 Z9 82 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP 485 EP 491 DI 10.1086/171448 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY145 UT WOS:A1992HY14500012 ER PT J AU KUSUNOSE, M MINESHIGE, S AF KUSUNOSE, M MINESHIGE, S TI GEOMETRICALLY THIN, HOT ACCRETION DISKS - TOPOLOGY OF THE THERMAL-EQUILIBRIUM CURVES SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; BLACK HOLE PHYSICS; RADIATION MECHANISMS, THERMAL ID BLACK-HOLES; PAIR PRODUCTION; BINARY-SYSTEMS; CYGNUS X-1; INSTABILITY; PLASMAS AB We present all the possible thermal equilibrium states of geometrically thin alpha-disks around stellar-mass black holes. We employ a (vertically) one-zone disk model and assume that a main energy source is viscous heating of protons and that cooling is due to bremsstrahlung and Compton scattering. Results can be summarized in the (SIGMA = surface density, M = accretion rate) plane. There exist various branches of the thermal equilibrium solution, depending on whether disks are effectively optically thick or thin, radiation pressure-dominated or gas pressure-dominated, composed of one-temperature plasmas or of two-temperature plasmas, and with high concentration of e+e- pairs or without pairs. The thermal equilibrium curves at high temperatures (T greater than or similar to 10(8) K) are substantially modified by the presence of e+e- pairs. The behavior of the pair-thermal equilibrium lines of the pair-dominated plasmas is well understood in the three-dimensional (SIGMA, M, z) space, where z is the ratio of positron density to proton density. We then examine the thermal stability of these branches. There are no thermally stable branches at high temperatures, T greater than or similar to 10(7) K, if the standard alpha-model is adopted and pair balance is assumed. A hard X-ray-emitting disk cannot therefore stay on any branches on time scales longer than the thermal time scales (of order 10 ms). It may be possible, however, that due to the limit cycle behavior, a disk stays around the high-temperature, pair-dominated solution in a quasi-steady manner. C1 IBARAKI UNIV,DEPT PHYS,BUNKYO KU,MITO,IBARAKI 310,JAPAN. UNIV CAMBRIDGE,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. RP KUSUNOSE, M (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES65,HUNTSVILLE,AL 35812, USA. NR 27 TC 15 Z9 15 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP 653 EP 661 DI 10.1086/171466 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY145 UT WOS:A1992HY14500030 ER PT J AU STOTHERS, RB AF STOTHERS, RB TI UPPER LIMIT TO THE MASS OF PULSATIONALLY STABLE STARS WITH UNIFORM CHEMICAL-COMPOSITION SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, EARLY-TYPE; STARS, FUNDAMENTAL PARAMETERS; STARS, INTERIORS; STARS, OSCILLATIONS; STARS, WOLF-RAYET ID MAIN-SEQUENCE STARS; WOLF-RAYET STARS; ETA-CARINAE; SPECKLE INTERFEROMETRY; MAGELLANIC CLOUDS; OPACITY TABLES; STABILITY; EVOLUTION; GALAXY; ULTRAVIOLET AB Nuclear-energized pulsational instability is a well-known feature of models of chemically homogeneous stars above a critical mass. With the new Rogers-Iglesias opacities, the instability occurs above 120-150 M. for normal Galactic Population I chemical compositions, and above approximately 90 M. for stars in metal-poor environments like the outer Galaxy and the Small Magellanic Cloud. Models of homogeneous helium-burning stars are unstable above masses of 19 and 14 M., respectively. These significant increases of the critical masses, in the normal metallicity cases, over the values derived previously with the Los Alamos opacities can explain the stability of the brightest observed O-type stars, but they do not exclude the possibility that the most luminous hydrogen-deficient Wolf-Rayet stars are experiencing this type of instability. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,GREENBELT,MD 20771, USA. NR 68 TC 24 Z9 24 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP 706 EP 709 DI 10.1086/171472 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY145 UT WOS:A1992HY14500036 ER PT J AU GARY, GA MUSIELAK, ZE AF GARY, GA MUSIELAK, ZE TI A REGULARIZATION METHOD FOR EXTRAPOLATION OF SOLAR POTENTIAL MAGNETIC-FIELDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; SUN, CORONA; SUN, MAGNETIC FIELDS ID FORCE-FREE FIELDS; CONSTANT-ALPHA; COMPUTATION; REGIONS AB This paper discusses the mathematical basis of a Tikhonov regularization method for extrapolating the chromospheric-coronal magnetic field using photospheric vector magnetograms. The basic techniques show that the Cauchy initial value problem can be formulated for potential magnetic fields. The potential field analysis considers a set of linear, elliptic partial differential equations. This analysis is the first step in the mathematical rigor needed for the direct numerical integration techniques for the general force-free magnetic field Cauchy problem. In this paper we present the results of this work by describing the mathematical formalism that has been developed following the work of V. K. Ivanov, extending his method to three dimensions, and developing the stability criteria and the accuracy level of extrapolated solutions as a function of the extrapolation height. The basic result of the paper is that, by introducing an appropriate smoothing of the initial data of the Cauchy potential problem, an approximate Fourier integral solution is found and an upper bound to the error in the solution is derived. The noise in the data would otherwise cause the solutions to diverge, but the smoothing decreases exponentially the contributions of the high spatial frequencies. As a result the solutions are approximations, but an upper bound on the difference between these quasi-solutions and the unique solution is explicitly derived as a function of height. This specific regularization technique, which is a function of magnetograph measurement sensitivities, provides a method to extrapolate the potential magnetic field above an active region into the chromosphere and low corona. For current measurement noise, the technique requires extensive smoothing and would give only large-scale magnetic structures above active regions. However, this initial study provides a solution, encouragement, and direction for mathematical research into linear and nonlinear regularization schemes for the ill-posed magnetostatic Cauchy problem. C1 UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899. UNIV ALABAMA,DEPT MECH ENGN,HUNTSVILLE,AL 35899. RP GARY, GA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB ES52,HUNTSVILLE,AL 35812, USA. NR 52 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP 722 EP 735 DI 10.1086/171475 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY145 UT WOS:A1992HY14500039 ER PT J AU JUSTTANONT, K BARLOW, MJ SKINNER, CJ TIELENS, AGGM AF JUSTTANONT, K BARLOW, MJ SKINNER, CJ TIELENS, AGGM TI THE NATURE OF DUST AROUND THE POST ASYMPTOTIC GIANT BRANCH OBJECTS HD-161796 AND HD-179821 SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; DUST, EXTINCTION; INFRARED, STARS; STARS, SUPERGIANTS ID PROTO-PLANETARY NEBULAE; NGC-6302; STARS; SUPERGIANTS; SPECTRA; GRAINS AB Ground-based 7.4-24-mu-m spectra of two post-AGB objects, HD 161796 and HD 179821, show emission features at 10-12-mu-m and at 19-mu-m. These features also appear to be present in the IRAS LRS spectrum of another post-AGB object, Roberts 22. HD 161796 and HD 179821 also exhibit a very rapid increase in flux between 13 and 15.5-mu-m. In view of the O-rich photosphere of HD 161796 and the presence of OH maser emission around all three objects, we ascribe these features to various oxides. However, the observed spectral features are quite different from the canonical silicate features observed in most O-rich giants. The 10-12 and 19-mu-m bands may be due to olivines and the rapid rise in flux between 13 and 15.5-mu-m may be due to iron oxides. We argue that HD 161796 and the bipolar nebulae Roberts 22 and NGC 6302 have all undergone the third dredge-up, with most of the dredged-up carbon having been converted to nitrogen by envelope-burning. Carbon-rich grain material, produced during the interval between the end of the third dredge-up and the moment when envelope burning finally reduced the C/O ratio below unity again, could be responsible for the UIR bands now being excited in Roberts 22 and NGC 6302. C1 NUFFIELD RADIO ASTRON LAB,LAWRENCE LIVERMORE NATL LAB,EXPTL ASTROPHYS LAB,JODRELL BANK,CA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. LAWRENCE LIVERMORE NATL LAB,INST GEOPHYS & PLANETARY PHYS,LIVERMORE,CA 94550. RP JUSTTANONT, K (reprint author), UNIV LONDON UNIV COLL,DEPT PHYS & ASTRON,GOWER ST,LONDON WC1E 6BT,ENGLAND. RI Barlow, Michael/A-5638-2009 OI Barlow, Michael/0000-0002-3875-1171 NR 32 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP L75 EP L78 DI 10.1086/186429 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY146 UT WOS:A1992HY14600008 ER PT J AU NEUPERT, WM BROSIUS, JW THOMAS, RJ THOMPSON, WT AF NEUPERT, WM BROSIUS, JW THOMAS, RJ THOMPSON, WT TI EVIDENCE FOR MASS OUTFLOW IN THE LOW SOLAR CORONA OVER A LARGE SUNSPOT SO ASTROPHYSICAL JOURNAL LA English DT Article DE SOLAR WIND; SUN, CORONA; SUN, UV RADIATION; SUNSPOTS ID EXTREME-ULTRAVIOLET OBSERVATIONS; MAGNETIC-FIELDS; TRANSITION ZONE; CHROMOSPHERE; TELESCOPE; EMISSION; HOLES; WIND AB Spatially resolved extreme ultraviolet (EUV) coronal emission-line profiles have been obtained in a solar active region, including a large sunspot, using an EUV imaging spectrograph. Relative Doppler velocities were measured in the lines of Mg IX, Fe xv, and Fe XVI with a sensitivity of 2-3 km s-1 at 350 angstrom. The only significant Doppler shift occurred over the umbra of the large sunspot, in the emission line of Mg ix (at T(e) almost-equal-to 1.1 x 10(6) K). The maximum shift corresponded to a peak velocity toward the observer of 14 +/- 3 km s-1 relative to the mean of measurements in this emission line made elsewhere over the active region. The magnetic field in the low corona was aligned to within 10-degrees of the line of sight at the location of maximum Doppler shift. Depending on the closure of the field, such a mass flow could either contribute to the solar wind or reappear as a downflow of material in distant regions on the solar surface. The site of the source, near a major photospheric field boundary, was consistent with origins of low-speed solar wind typically inferred from interplanetary plasma observations. RP NEUPERT, WM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Thompson, William/D-7376-2012 NR 30 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP L95 EP L98 DI 10.1086/186434 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY146 UT WOS:A1992HY14600013 ER PT J AU RAMATY, R LEVENTHAL, M CHAN, KW LINGENFELTER, RE AF RAMATY, R LEVENTHAL, M CHAN, KW LINGENFELTER, RE TI ON THE ORIGIN OF VARIABLE 511 KEV LINE EMISSION FROM THE GALACTIC-CENTER REGION SO ASTROPHYSICAL JOURNAL LA English DT Article DE BLACK HOLE PHYSICS; GALAXY, CENTER; GAMMA-RAYS, OBSERVATIONS; GAMMA-RAYS, THEORY ID POSITRON-ANNIHILATION RADIATION; CENTER DIRECTION; CONTINUUM; PLASMA AB Variable narrow-line emission at 511 keV, due to positron annihilation, has been observed from the region of the Galactic center for over a decade with high-resolution Ge spectrometers. The variable nature of this emission suggests that a significant fraction of the observed radiation is produced by a single source in the central region of the Galaxy. Recent observations with an imaging gamma-ray spectrometer of low energy resolution have revealed a daylong burst of annihilation radiation from the X-ray source 1E 1740.7-2942 located at an angular distance of 0.9-degrees from the Galactic center and aligned with a dense molecular cloud. We propose that the variable narrow 511 keV line emission is due to positrons released impulsively (time scale approximately 1 day) from 1E 1740.7 - 2942 into the molecular cloud where they slow down and annihilate on a longer time scale of up to a year. C1 UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. RP RAMATY, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 36 TC 66 Z9 66 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP L63 EP L66 DI 10.1086/186426 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY146 UT WOS:A1992HY14600005 ER PT J AU ROSENQVIST, J LELLOUCH, E ROMANI, PN PAUBERT, G ENCRENAZ, T AF ROSENQVIST, J LELLOUCH, E ROMANI, PN PAUBERT, G ENCRENAZ, T TI MILLIMETER-WAVE OBSERVATIONS OF SATURN, URANUS, AND NEPTUNE - CO AND HCN ON NEPTUNE SO ASTROPHYSICAL JOURNAL LA English DT Article DE PLANETS AND SATELLITES, INDIVIDUAL (NEPTUNE, SATURN, URANUS) ID CARBON-MONOXIDE; ATMOSPHERE; JUPITER; PHOTOCHEMISTRY; IONOSPHERE; TRITON; MODEL; RINGS; TITAN; PH3 AB Saturn, Uranus, and Neptune were observed at millimeter wavelengths with the IRAM 30 m telescope. T major result is the detection of CO and HCN in Neptune's stratosphere, with respective mixing ratios of (6.5 +/- 3.5) x 10(-7) and (3 +/- 1.5) x 10(-10). CO seems to be present in Neptune's troposphere as well and to slowly decrease with altitude (scale height approximately 200 km). HCN is probably formed from reactions between CH3 and N, which can be supplied in sufficient amounts by escape from Triton's atmosphere. The origin of CO, however, is more problematic, because (i) thermochemical models fail to reproduce the observed abundance by a factor approximately 1000 and (ii) an external source would require a very large flux of oxygen. CO appears to be at least 15 times less abundant on Uranus than on Neptune. Finally, an upper limit of 10(-7) for CO in Saturn's stratosphere suggests an internal origin for Saturnian CO. C1 INST RADIOASTRON MILLIMETR,GRANADA,SPAIN. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP ROSENQVIST, J (reprint author), OBSERV PARIS,DEPT SPATIAL,F-92195 MEUDON,FRANCE. RI Romani, Paul/D-2729-2012 NR 31 TC 53 Z9 53 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP L99 EP L102 DI 10.1086/186435 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY146 UT WOS:A1992HY14600014 ER PT J AU SHORE, SN BRAINE, J AF SHORE, SN BRAINE, J TI UPPER LIMITS FOR CO IN THE OLD GALACTIC NOVAE NQ VULPECULAE, QU VULPECULAE, AND NOVA VULPECULAE 1987 FROM IRAM OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE NOVAE, CATACLYSMIC VARIABLES; RADIO LINES, MOLECULAR, CIRCUMSTELLAR ID CLASSICAL NOVAE AB We have observed three Galactic novae with the IRAM 30 m telescope at (CO)-C-12 J = 1 --> 0 and J = 2 --> 1. We find no evidence for the previously reported emission in NQ Vul and derive strong upper limits for possible CO emission in QU Vul and Nova Vul 1987. There is no evidence for extensive cold molecular material surrounding old novae. C1 OBSERV MEUDON,DEMIRM,F-92195 MEUDON,FRANCE. RP SHORE, SN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON PROGRAMS,GHRS SCI TEAM,CODE 681,GREENBELT,MD 20771, USA. NR 17 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1992 VL 392 IS 2 BP L59 EP L61 DI 10.1086/186425 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY146 UT WOS:A1992HY14600004 ER PT J AU HUBLER, G FAHEY, DW RIDLEY, BA GREGORY, GL FEHSENFELD, FC AF HUBLER, G FAHEY, DW RIDLEY, BA GREGORY, GL FEHSENFELD, FC TI AIRBORNE MEASUREMENTS OF TOTAL REACTIVE ODD NITROGEN (NOY) SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID PEROXYACETYL NITRATE PAN; FREE TROPOSPHERE; PARTICULATE NITRATE; OZONE PRODUCTION; EASTERN PACIFIC; BOUNDARY-LAYER; UNITED-STATES; NITRIC-OXIDE; DISTRIBUTIONS; STRATOSPHERE AB Airborne total reactive odd nitrogen measurements were made during August and September 1986 over the continental United States and off the west coast over the Pacific Ocean during NASAs Global Tropospheric Experiment/Chemical Instrumentation Test and Evaluation 2 program. The NOy instrument combined a catalytic surface converter which reduced NOy component species to NO on a heated Au surface with a NO/O3 chemiluminescence detector. Measurements were made in the marine and continental boundary layer and the free troposphere up to 6.1 km altitude. NOy mixing ratios between 24 pptv and more than 1 ppbv were found, with median values of 101 pptv in the marine boundary layer, 298 pptv in the marine free troposphere, and 288 pptv in the continental free troposphere, respectively. The marine troposphere exhibited layered structure which was also seen in die simultaneously measured ozone mixing ratio and dew point temperature. The averaged vertical NOy profile over the ocean does not show a distinct gradient. The NOy mixing ratio over the continent decreases with increasing altitude. The latter is consistent with our understanding that the continents are the major source region for these gases. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NATL CTR ATMOSPHER RES, DIV ATMOSPHER CHEM, BOULDER, CO 80307 USA. RP HUBLER, G (reprint author), NOAA, AERON LAB, BOULDER, CO 80303 USA. RI Hubler, Gerhard/E-9780-2010; Fehsenfeld, Frederick/I-4876-2013; Fahey, David/G-4499-2013 OI Fahey, David/0000-0003-1720-0634 NR 45 TC 37 Z9 37 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 20 PY 1992 VL 97 IS D9 BP 9833 EP 9850 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JA769 UT WOS:A1992JA76900006 ER PT J AU PRICE, C RIND, D AF PRICE, C RIND, D TI A SIMPLE LIGHTNING PARAMETERIZATION FOR CALCULATING GLOBAL LIGHTNING DISTRIBUTIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MOBILE SOUNDING OBSERVATIONS; NINO-SOUTHERN OSCILLATION; VERTICAL VELOCITY EVENTS; MESOSCALE SYSTEMS; CONVECTIVE CELLS; DOPPLER RADAR; TEXAS STORM; THUNDERSTORM; HURRICANES; GATE AB A simple parameterization has been developed to simulate global lightning distributions. Convective cloud top height is used as the variable in the parameterization, with different formulations for continental and marine thunderstorms. The parameterization has been validated using two lightning data sets: one global and one regional. In both cases the simulated lightning distributions and frequencies are in very good agreement with the observed lightning data. This parameterization could be used for global studies of lightning climatology; the Earth's electric circuit; in general circulation models for modeling global lightning activity, atmospheric NOx concentrations, and perhaps forest fire distributions for both the present and future climate; and, possibly, even as a short-term forecasting aid. RP PRICE, C (reprint author), NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. NR 65 TC 357 Z9 364 U1 2 U2 33 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 20 PY 1992 VL 97 IS D9 BP 9919 EP 9933 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JA769 UT WOS:A1992JA76900014 ER PT J AU WU, MLC CHANG, LP AF WU, MLC CHANG, LP TI LONGWAVE RADIATION BUDGET PARAMETERS COMPUTED FROM ISCCP AND HIRS2 MSU PRODUCTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DIURNAL VARIABILITY; EXPERIMENT ERBE; REGIONAL CLOUD; TIROS-N; SATELLITE; CLIMATE; FLUX; SOUNDINGS; NIMBUS-7 AB Despite the large discrepancies between the International Satellite Cloud Climatology Project (ISCCP) retrieved cloud fields and the high-resolution infrared radiation sounder 2 (HIRS2) retrieved cloud fields, the outgoing longwave radiation (OLR) computed based on these two cloud fields are quite similar due to the cancelation effect of cloud top altitudes and cloud amount on OLR. The accuracy of temperatures and humidities on the computation of OLR is as important as the clouds. For example, the large regional discrepancies of the order of 30 W m-2 found over northern Africa are largely due to surface temperature differences. Most extensive discrepancies over the ocean are due to humidity differences. Harmonic analysis has been applied to OLR, clear sky OLR, and cloud radiative forcing at the top of the atmosphere for July 1983 using the ISCCP products. The results show that the diurnal variations of these parameters from 60-degrees-S to 60-degrees-N are larger over land than over the ocean. The clear sky OLR peaks around 1500 LST, usually over land areas, and is associated with the surface/air temperature maximum. The OLR over cloudy regions shows a similar diurnal phase as the cloud top pressure. The cloud radiative forcing at the top of the atmosphere has maximum value near 2100 LST over the U.S. Rocky Mountain areas and near 0000 and 0300 LST over equatorial Africa and southern portions of North Africa. The ISCCP-computed longwave cloud radiative forcing has smaller diurnal variations over the ocean than the HIRS2-computed longwave cloud radiative forcing. The difference between the twice-a-day monthly mean and the 8-times-a-day monthly mean is small when using the ISCCP cloud products. The global mean bias of OLR from 60-degrees-S to 60-degrees-N is around 0.74 W m-2 with a standard deviation of 1.57 W m-2. Locally, the bias can be as large as 5 to 10 W m-2. This appears to indicate that the twice-a-day measurements of the HIRS2/MSU (around 0315 and 1515 LST, which are the equatorial cross times at nadir track) can be used to derive monthly mean OLR without significant bias. RP WU, MLC (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, MAIL CODE 911, GREENBELT, MD 20771 USA. NR 23 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 20 PY 1992 VL 97 IS D9 BP 10083 EP 10101 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JA769 UT WOS:A1992JA76900025 ER PT J AU RENDELL, AP LEE, TJ LINDH, R AF RENDELL, AP LEE, TJ LINDH, R TI QUANTUM-CHEMISTRY ON PARALLEL COMPUTER ARCHITECTURES - COUPLED-CLUSTER THEORY APPLIED TO THE BENDING POTENTIAL OF FULMINIC ACID SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; ROW ATOMS; CONTRACTION; CONVERGENCE AB We present a formulation of the singles and doubles coupled-cluster (CCSD) method suitable for distributed memory parallel computer architectures. Results from test calculations using up to 128 nodes of the Intel i860 hypercube are presented. Although the new algorithm is highly parallel, the asymptotic speed is quickly reached due to the input/output (IO) demands on the concurrent file system. To alleviate these IO problems, as well as disk storage requirements, we propose a "semi-direct" CCSD method whereby the atomic orbital integrals are evaluated in each iteration of the procedure in order to determine the contribution from certain terms. Using CCSD(T)/TZ2P optimized geometries, the calculations show that the Born-Oppenheimer ground-state potential energy surface yields a linear structure for fulminic acid. HCNO, in agreement with the semirigid bender analysis by Bunker, Landsberg and Winnewisser. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV LUND, DEPT THEORET CHEM, S-22000 LUND, SWEDEN. RP RENDELL, AP (reprint author), SERC, DARESBURY LAB, WARRINGTON WA4 4AD, CHESHIRE, ENGLAND. RI Rendell, Alistair/A-4883-2008; Lindh, Roland/F-3471-2012; Lee, Timothy/K-2838-2012 OI Rendell, Alistair/0000-0002-9445-0146; Lindh, Roland/0000-0001-7567-8295; NR 33 TC 60 Z9 60 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUN 19 PY 1992 VL 194 IS 1-2 BP 84 EP 94 DI 10.1016/0009-2614(92)85747-X PG 11 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA JA660 UT WOS:A1992JA66000015 ER PT J AU KRUEGER, A SCHOEBERL, M NEWMAN, P STOLARSKI, R AF KRUEGER, A SCHOEBERL, M NEWMAN, P STOLARSKI, R TI THE 1991 ANTARCTIC OZONE HOLE - TOMS OBSERVATIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID QUASI-BIENNIAL OSCILLATION AB The 1991 Antarctic springtime ozone decline, as measured by the Total Ozone Mapping Spectrometer (TOMS), was similar to those of earlier deep ozone hole years, 1987, 1989, and 1990. The minimum total ozone value was recorded on October 5, 1991 at 108 Dobson units near the South Pole. This was 8 DU lower than in any of the earlier years. Four of the last five years have exhibited an extensive, deep ozone hole. The area of the hole was about the same as in 1987, 1989, and 1990. The recovery of the low total ozone values occurred in mid-November as the polar vortex broke up. RP KRUEGER, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 916,GREENBELT,MD 20771, USA. RI Newman, Paul/D-6208-2012; Stolarski, Richard/B-8499-2013 OI Newman, Paul/0000-0003-1139-2508; Stolarski, Richard/0000-0001-8722-4012 NR 27 TC 10 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1215 EP 1218 DI 10.1029/92GL01113 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400010 ER PT J AU VIERECK, RA MENDE, SB MURAD, E SWENSON, GR PIKE, CP CULBERTSON, FL SPRINGER, RC AF VIERECK, RA MENDE, SB MURAD, E SWENSON, GR PIKE, CP CULBERTSON, FL SPRINGER, RC TI SPECTRAL CHARACTERISTICS OF SHUTTLE GLOW SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SURFACE; MODEL AB The glowing cloud near the ram surfaces of the Space Shuttle was observed with a hand-held, intensified spectrograph operated by the astronauts from the aft-flightdeck of the space shuttle. The spectral measurements were made between 400 and 800 nm with a resolution of 3 nm. Analysis of the spectral response of the instrument and the transmission of the shuttle window was performed on orbit using earth-airglow OH Meinel bands. This analysis resulted in a correction of the shuttle glow intensity in the spectral region between 700 and 800 nm. The data presented in this report is in better agreement with laboratory measurements of the NO2 continuum. C1 LOCKHEED PALO ALTO RES LABS,RES & DEV,PALO ALTO,CA 94304. NASA,LYNDON B JOHNSON SPACE CTR,ASTRONAUT OFF,HOUSTON,TX 77058. RP VIERECK, RA (reprint author), PHILLIPS LAB,SPACECRAFT INTERACT BRANCH,HANSCOM AFB,BEDFORD,MA 01731, USA. NR 23 TC 16 Z9 16 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1219 EP 1222 DI 10.1029/92GL01111 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400011 ER PT J AU WENZEL, KP SMITH, EJ AF WENZEL, KP SMITH, EJ TI THE ULYSSES MISSION - IN-ECLIPTIC PHASE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article C1 EUROPEAN SPACE AGCY,DEPT SPACE SCI,2200 AG NOORDWIJK,NETHERLANDS. RP WENZEL, KP (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 2 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1235 EP 1237 DI 10.1029/92GL01024 PG 3 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400015 ER PT J AU PHILLIPS, JL BAME, SJ GOSLING, JT MCCOMAS, DJ GOLDSTEIN, BE SMITH, EJ BALOGH, A FORSYTH, RJ AF PHILLIPS, JL BAME, SJ GOSLING, JT MCCOMAS, DJ GOLDSTEIN, BE SMITH, EJ BALOGH, A FORSYTH, RJ TI ULYSSES PLASMA OBSERVATIONS OF CORONAL MASS EJECTIONS NEAR 2.5 AU SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The Ulysses solar wind plasma experiment observed a series of interplanetary shocks and coronal mass ejections (CMEs), the latter evidenced by counterstreaming electrons and a variety of ion signatures, during March and April 1991. A striking sequence was observed near 2.5 AU from March 23 through April 2, with the second of two counterstreaming events lasting 6.4 days. We summarize the plasma observations for these features, suggesting that the second counterstreaming period may be two juxtaposed CMEs. The relationship between the events observed at Ulysses, approximately 60-degrees east of Earth in ecliptic longitude, and those causing a geomagnetic storm on March 24, is unclear. C1 JET PROP LAB,PASADENA,CA 91109. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. RP PHILLIPS, JL (reprint author), LOS ALAMOS NATL LAB,MS-D438,LOS ALAMOS,NM 87545, USA. NR 9 TC 27 Z9 27 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1239 EP 1242 DI 10.1029/92GL00529 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400016 ER PT J AU TSURUTANI, BT SOUTHWOOD, DJ SMITH, EJ BALOGH, A AF TSURUTANI, BT SOUTHWOOD, DJ SMITH, EJ BALOGH, A TI NONLINEAR MAGNETOSONIC WAVES AND MIRROR MODE STRUCTURES IN THE MARCH 1991 ULYSSES INTERPLANETARY EVENT SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CORONA; COMETS; MAGNETOSHEATH; UPSTREAM; PACKETS AB In examining the March 23-25, 1991 Ulysses (2.2 AU) high speed solar wind events, we find two distinct plasma wave modes: steepened magnetosonic waves with whistler precursors and mirror mode structures. These two modes are locally generated by plasma instabilities, presumably associated with anisotropies existing in the energetic shock particles and solar wind plasma, respectively. The magnetosonic waves are generated by a righthand resonant instability associated with a approximately 40 keV ion beam. By an extrapolation of the results presented here, assuming microflares and nanoflares at the Sun generate shocks in the lower corona and these shocks accelerate energetic ions, we suggest that the ions, via the right-hand resonant instability, generate magnetosonic waves which steepened to form "microshocks" (such as shown here). These shocks could, in tum, accelerate more energetic ions, leading to a shock/energetic ion/magnetosonic wave cascade. These newly formed magnetosonic waves and shocks presumably could propagate in a broad range of directions, leading to energy dissipation over a large region of the outer corona. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,LONDON SW7 2AZ,ENGLAND. RP TSURUTANI, BT (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 24 TC 66 Z9 66 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1267 EP 1270 DI 10.1029/92GL00782 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400023 ER PT J AU REINER, MJ STONE, RG FAINBERG, J AF REINER, MJ STONE, RG FAINBERG, J TI UNUSUAL RADIO AND PLASMA-WAVE PHENOMENA OBSERVED IN MARCH 1991 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR AB During the intense solar flare activity in March 1991 a number of unusual radio emission and Langmuir wave phenomena were observed by the radio and plasma wave (URAP) experiment on the Ulysses spacecraft. These phenomena were associated with unusual conditions in the interplanetary medium (IPM) presumably resulting from intense solar activity. Some of these URAP observations cannot be explained by mechanisms usually attributed to interplanetary (IP) radio emissions and Langmuir wave activity and require other interpretations. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP REINER, MJ (reprint author), HUGHES STX,LANHAM,MD, USA. NR 13 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1271 EP 1274 DI 10.1029/92GL00389 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400024 ER PT J AU REINER, MJ STONE, RG FAINBERG, J AF REINER, MJ STONE, RG FAINBERG, J TI OBSERVATION OF NONDRIFTING RADIO EMISSIONS ASSOCIATED WITH THE INTENSE SOLAR-ACTIVITY IN MARCH 1991 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BURSTS AB Three very unusual radio bursts, separated in time by 4 hours and 35 minute-intervals were observed on March 28, 1991 by the radio and plasma wave (URAP) experiment on the Ulysses spacecraft. Although they are preceded by drifting type III bursts at high frequencies, they show no frequency drift at frequencies from 52 kHz down to 16 kHz. In addition, they have extraordinary sawtooth-like profiles; they have a very rapid exponential rise of about 20 minutes independent of frequency and a much longer nonexponential decay which increases with decreasing frequency. The bursts are interpreted as due to synchrotron emission, which seems to fit many of their characteristics. This radio emission appears to be associated with an expanding source region. However, the observed intensity may be somewhat higher than expected and the possible role of the precursor type III radio bursts in triggering the low frequency non-drifting emission remains unanswered. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP REINER, MJ (reprint author), HUGHES STX,LANHAM,MD, USA. NR 16 TC 4 Z9 4 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1275 EP 1278 DI 10.1029/92GL00338 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400025 ER PT J AU BURTON, ME SMITH, EJ GOLDSTEIN, BE BALOGH, A FORSYTH, RJ BAME, SJ AF BURTON, ME SMITH, EJ GOLDSTEIN, BE BALOGH, A FORSYTH, RJ BAME, SJ TI ULYSSES - INTERPLANETARY SHOCKS BETWEEN 1-AU AND 4-AU SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND AB The complex solar events of March 1991 are evident as a large increase in the rate of occurrence of interplanetary shocks. Using Ulysses magnetic field and plasma measurements, 32 forward shocks and 7 reverse shocks have been identified in the 280 day interval from October 26, 1990 to August 1, 1991. The March events alone have produced 9 shocks, several in association with coronal mass ejections. The shocks have been identified and analyzed to find theta(BN), the speeds in the upstream solar wind, the Mach number and the inertial speeds along the radial and magnetic field directions. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP BURTON, ME (reprint author), JET PROP LAB,MS 169-506,PASADENA,CA 91109, USA. NR 15 TC 30 Z9 30 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1287 EP 1289 DI 10.1029/92GL01284 PG 3 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400028 ER PT J AU HOANG, S MEYERVERNET, N BOUGERET, JL HARVEY, CC LACOMBE, C MANGENEY, A MONCUQUET, M PERCHE, C STEINBERG, JL MACDOWALL, RJ STONE, RG AF HOANG, S MEYERVERNET, N BOUGERET, JL HARVEY, CC LACOMBE, C MANGENEY, A MONCUQUET, M PERCHE, C STEINBERG, JL MACDOWALL, RJ STONE, RG TI SOLAR-WIND THERMAL ELECTRONS IN THE ECLIPTIC-PLANE BETWEEN 1-AU AND 4-AU - PRELIMINARY-RESULTS FROM THE ULYSSES RADIO RECEIVER SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID NOISE; PLASMA; ISEE-3 AB The radio receiver of the Unified Radio and Plasma (URAP) experiment aboard the Ulysses spacecraft records spectra of the quasi-thermal plasma noise. The interpretation of these spectra allows the determination of the total electron density Ne and of the cold (core) electron temperature Tc in the solar wind. A single power law does not fit the variations of Ne which result from the contribution from different solar wind structures. The distribution of the values of Tc suggests that, on the average, the solar wind is nearly isothermal. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP HOANG, S (reprint author), OBSERV PARIS,DEPT RECH SPATIALE,CNRS,URA 264,F-92195 MEUDON,FRANCE. RI MacDowall, Robert/D-2773-2012 NR 11 TC 18 Z9 18 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1295 EP 1298 DI 10.1029/92GL00784 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400030 ER PT J AU LECACHEUX, A PEDERSEN, BM ZARKA, P AUBIER, MG DESCH, MD FARRELL, WM KAISER, ML MACDOWALL, RJ STONE, RG AF LECACHEUX, A PEDERSEN, BM ZARKA, P AUBIER, MG DESCH, MD FARRELL, WM KAISER, ML MACDOWALL, RJ STONE, RG TI IN ECLIPTIC OBSERVATIONS OF JOVIAN RADIO EMISSIONS BY ULYSSES COMPARISON WITH VOYAGER RESULTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID KILOMETRIC RADIATION; POLARIZATION; JUPITER AB During the Ulysses inbound cruise to Jupiter the Unified Radio and Plasma Wave (URAP) experiment observed a variety of the planet's radio components in the frequency range below 1 MHz. Most of these emissions were already detected by the Voyager Radio Astronomy (PRA) and Plasma Wave (PWS) experiments, however with much less sensitivity and different spectral coverage. We identify these different radio components within the URAP dynamic spectra and compare their appearance with the previous Voyager observations. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP LECACHEUX, A (reprint author), OBSERV PARIS,CNRS,URA 324,F-92190 MEUDON,FRANCE. RI MacDowall, Robert/D-2773-2012; Farrell, William/I-4865-2013 NR 19 TC 20 Z9 20 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1307 EP 1310 DI 10.1029/92GL01037 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400033 ER PT J AU GRUN, E BAGUHL, M FECHTIG, H HANNER, MS KISSEL, J LINDBLAD, BA LINKERT, D LINKERT, G MANN, I MCDONNELL, JAM MORFILL, GE POLANSKEY, C RIEMANN, R SCHWEHM, G SIDDIQUE, N ZOOK, HA AF GRUN, E BAGUHL, M FECHTIG, H HANNER, MS KISSEL, J LINDBLAD, BA LINKERT, D LINKERT, G MANN, I MCDONNELL, JAM MORFILL, GE POLANSKEY, C RIEMANN, R SCHWEHM, G SIDDIQUE, N ZOOK, HA TI GALILEO AND ULYSSES DUST MEASUREMENTS - FROM VENUS TO JUPITER SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The Galileo and Ulysses spaceprobes carry two similar dust detectors through interplanetary space from Venus to Jupiter. We report here on impacts which correspond to dust particles above a mass threshold of about 10(-13)g for which we have complete records. Between December 1989 and January 1992 Galileo repeatedly traversed interplanetary space between 0.7 and 2.26 AU and recorded 374 impacts. The observed impact rates ranged from 0.1 to about 3 impacts per day strongly dependent on whether the spacecraft moved towards or away from the Sun. From October 1990 to January 1992 the Ulysses spacecraft had reached a distance of 5.17 AU from the Sun and had recorded 72 impacts at rates between 0.1 and 0.5 per day. Inside about 2 AU the observed fluxes are compatible with a population of interplanetary dust particles moving on low to moderately eccentric (e = 0.1 to 0.5) and low inclination (i = 0 deg. to 30 deg.) orbits. Outside this distance a dust particle population on different orbits is required in order to explain the Ulysses data. C1 MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. MAX PLANCK INST EXTRATERRESTR PHYS,W-8046 GARCHING,GERMANY. JET PROP LAB,PASADENA,CA 91109. LUND OBSERV,S-221 LUND,SWEDEN. UNIV KENT,CANTERBURY CT 7NR,KENT,ENGLAND. EUROPEAN SPACE AGCY,EUROPEAN SPACE RES & TECHNOL CTR,2200 AG NOORDWIJK,NETHERLANDS. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP GRUN, E (reprint author), MAX PLANCK INST NUCL PHYS,W-6900 HEIDELBERG 1,GERMANY. NR 14 TC 25 Z9 25 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 19 PY 1992 VL 19 IS 12 BP 1311 EP 1314 DI 10.1029/92GL00629 PG 4 WC Geosciences, Multidisciplinary SC Geology GA JA744 UT WOS:A1992JA74400034 ER PT J AU TONG, LU MEHREGANY, M AF TONG, LU MEHREGANY, M TI MECHANICAL-PROPERTIES OF 3C-SILICON CARBIDE SO APPLIED PHYSICS LETTERS LA English DT Article ID THIN-FILMS AB The residual stress and Young's modulus of 3C silicon carbide (SiC) epitaxial films deposited on silicon substrates were measured by load-deflection measurements using suspended SiC diaphragms fabricated with silicon micromachining techniques. The film's residual stress was tensile and averaged 274 MPa while the in-plane Young's modulus averaged 394 GPa. In addition, the bending moment due to the residual stress variation through the thickness of the film was determined by measuring the deflection of free-standing 3C-SiC cantilever beams. The bending moment was in the range of 2.6X10(-8)-4.2X10(-8) N m. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP TONG, LU (reprint author), CASE WESTERN RESERVE UNIV,DEPT ELECT ENGN & APPL PHYS,CTR ELECTR DESIGN,CLEVELAND,OH 44106, USA. NR 12 TC 87 Z9 93 U1 1 U2 11 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUN 15 PY 1992 VL 60 IS 24 BP 2992 EP 2994 DI 10.1063/1.106786 PG 3 WC Physics, Applied SC Physics GA HY988 UT WOS:A1992HY98800015 ER PT J AU JAHNKE, LL AF JAHNKE, LL TI THE EFFECTS OF GROWTH TEMPERATURE ON THE METHYL STEROL AND PHOSPHOLIPID FATTY-ACID COMPOSITION OF METHYLOCOCCUS-CAPSULATUS (BATH) SO FEMS MICROBIOLOGY LETTERS LA English DT Article DE METHYLOCOCCUS-CAPSULATUS; UNSATURATED FATTY ACID; METHYL STEROL; TEMPERATURE EFFECT ID POSITIONAL ISOMERS; MEMBRANE-LIPIDS; CHOLESTEROL; METHANE; ORDER AB Growth of Methylococcus capsulatus (Bath) at temperatures ranging from 30 to 50-degrees-C resulted in changes to the whole cell lipid constituents. As temperature was lowered, the overall proportion of hexadecenoic acid (C16:1) increased, and the relative proportions of the DELTA-9, DELTA-10 and DELTA-11 C16:1 double bond positional isomers changed. Methyl sterol content also increased as the growth temperature was lowered. The highest amounts of methyl sterol were found in 30-degrees-C cells and the lowest in 50-degrees-C cells (sterol-phospholipid ratios of 0.077 and 0.013, respectively). The data are consistent with a membrane modulating role for the sterol produced by this prokaryotic organism. RP JAHNKE, LL (reprint author), NASA,AMES RES CTR,M-S 239-4,MOFFETT FIELD,CA 94035, USA. NR 22 TC 23 Z9 23 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0378-1097 J9 FEMS MICROBIOL LETT JI FEMS Microbiol. Lett. PD JUN 15 PY 1992 VL 93 IS 3 BP 209 EP 212 DI 10.1111/j.1574-6968.1992.tb05099.x PG 4 WC Microbiology SC Microbiology GA HZ441 UT WOS:A1992HZ44100002 ER PT J AU GUPTA, KK LAWSON, CL AHMADI, AR AF GUPTA, KK LAWSON, CL AHMADI, AR TI ON DEVELOPMENT OF A FINITE DYNAMIC ELEMENT AND SOLUTION OF ASSOCIATED EIGENPROBLEM BY A BLOCK LANCZOS PROCEDURE SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article ID FREE-VIBRATION ANALYSIS; ALGORITHM AB The paper first presents the details of the development of a new six-noded plane triangular finite dynamic element. A block Lanczos algorithm is developed next for the accurate and efficient solution of the quadratic matrix eigenvalue problem associated with the finite dynamic element formulation. The resulting computer program fully exploits matrix sparsity inherent in such a discretization and proves to be most efficient for the extraction of the usually required first few roots and vectors, including repeated ones. Most importantly, the present eigenproblem solution effort is shown to be comparable to that of the corresponding finite element analysis, thereby rendering the associated dynamic element method rather attractive owing to superior convergence characteristics of such elements, presented herein. C1 ELORET INST, CLAREMONT, CA USA. RP NASA, AMES RES CTR, DRYDEN FLIGHT RES FACIL, EDWARDS, CA 93523 USA. NR 9 TC 8 Z9 8 U1 0 U2 1 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0029-5981 EI 1097-0207 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD JUN 15 PY 1992 VL 33 IS 8 BP 1611 EP 1623 DI 10.1002/nme.1620330805 PG 13 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA HU504 UT WOS:A1992HU50400004 ER PT J AU SHING, YH RICH, DH POOL, FS AF SHING, YH RICH, DH POOL, FS TI DEPENDENCE OF THE CATHODOLUMINESCENCE OF DIAMOND FILMS ON DEPOSITION TEMPERATURE SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID CHEMICAL-VAPOR-DEPOSITION; GAS-PHASE; PLASMA AB The deposition temperature dependence of the cathodoluminescence (CL) of diamond thin films grown by microwave plasma-assisted chemical vapor deposition has been investigated. Depositions were made in the temperature range of 400 to 750-degrees-C at a pressure of 10 Torr, with a gas mixture of 5% CH4 and 5% 02 in hydrogen. The intensity of the luminescent peak at 430 nm was used as a measure of diamond quality for the film. This peak was found to be a maximum above 600-degrees-C. Examination of the intensities of CL emissions associated with nitrogen and silicon impurities at 530, 560, and 740 nm indicate incorporation of these impurities is more efficient at temperatures above 600-degrees-C. Film quality was thus found to be an optimization of competing mechanisms, i.e., improvement of diamond quality as evidenced by the intensity of the 430 nm peak, with the apparent activation of impurities and vacancy defects at elevated temperatures. RP SHING, YH (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 11 TC 3 Z9 3 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUN 15 PY 1992 VL 71 IS 12 BP 6036 EP 6038 DI 10.1063/1.350460 PG 3 WC Physics, Applied SC Physics GA HZ316 UT WOS:A1992HZ31600045 ER PT J AU MA, Q TIPPING, RH AF MA, Q TIPPING, RH TI A FAR WING LINE-SHAPE THEORY AND ITS APPLICATION TO THE WATER VIBRATIONAL BANDS (II) SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CONTINUUM ABSORPTION; STATISTICAL-THEORY; ROTATIONAL BANDS; VAPOR CONTINUUM; SPECTRAL REGION; WINDOW AB A far wing line shape theory based on the binary collision and quasistatic approximations that is applicable for both the low and high frequency wings of vibration-rotational bands is presented. This theory is applied in order to calculate the frequency and temperature dependence of the continuous absorption coefficient for frequencies up to 10 000 cm-1 for pure water vapor. The calculations are made assuming an interaction potential consisting of an isotropic Lennard-Jones part with two parameters that are consistent with values obtained from virial data and the anisotropic dipole-dipole part, together with measured line strengths and positions of allowed transitions. The results are compared with existing laboratory data in the 2400-2700 cm-1 window and in the 3000-4300 cm-1 band center region, with field measurements in the 2000-2225 cm-1 region and with a recent experimental measurement near 9466 cm-1. The overall good agreement, together with even better agreement with the more accurate laboratory data in the 300-1100 cm-1 window presented previously, allows us to conclude that both the magnitude and temperature dependence of the water vapor continuum can be accounted for by our comprehensive far wing line shape theory without the introduction of any adjustable parameters. Refinements of the present theory and extension to foreign-broadened absorption are also discussed briefly. C1 GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. HARVARD SMITHSONIAN CTR ASTROPHYS,INST THEORET ATOM & MOLEC PHYS,CAMBRIDGE,MA 02138. UNIV ALABAMA,DEPT PHYS & ASTRON,TUSCALOOSA,AL 35487. RP MA, Q (reprint author), COLUMBIA UNIV,CTR STUDY GLOBAL HABITABIL,NEW YORK,NY 10025, USA. NR 32 TC 36 Z9 39 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUN 15 PY 1992 VL 96 IS 12 BP 8655 EP 8663 DI 10.1063/1.462272 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA HZ098 UT WOS:A1992HZ09800001 ER PT J AU LEE, TJ KOBAYASHI, R HANDY, NC AMOS, RD AF LEE, TJ KOBAYASHI, R HANDY, NC AMOS, RD TI COMPARISON OF THE BRUECKNER AND COUPLED-CLUSTER APPROACHES TO ELECTRON CORRELATION SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID QUADRATIC CONFIGURATION-INTERACTION; GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FULL CCSDT MODEL; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; TRIPLE EXCITATIONS; VIBRATIONAL FREQUENCIES; PERTURBATION-THEORY; 5TH-ORDER AB The equilibrium structures, dipole moments, harmonic vibrational frequencies, and infrared intensities of NH3, FON, Be3, BeC2, and BeO2 have been determined using the coupled-cluster and Brueckner electron correlation methods. The singles and doubles coupled-cluster (CCSD) and the Brueckner doubles (BD) methods have been employed and the corresponding methods that include a perturbational estimate of connected triple excitations [i.e., CCSD(T) and BD(T)] have also been investigated. The T1 diagnostic [Int. J. Quantum Chem. Symp. 23, 199 (1989)] is found to provide a good indication of the magnitude of the difference between the results obtained with the coupled-cluster and Brueckner methods. For NH3, the T1 diagnostic is small and so the differences between results obtained from coupled-cluster and Brueckner theories are quite small. For the other four molecules the T1 diagnostic is larger, and so the differences between the coupled-cluster and Brueckner methods become larger. However, it is found for all of the molecules considered in this study that inclusion of the contribution from connected triple excitations is more important than the differences between the Brueckner and coupled-cluster correlation methods. C1 UNIV CAMBRIDGE, CHEM LAB, CAMBRIDGE CB2 1EW, ENGLAND. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Lee, Timothy/K-2838-2012 NR 45 TC 43 Z9 43 U1 0 U2 9 PU AMER INST PHYSICS PI MELVILLE PA CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUN 15 PY 1992 VL 96 IS 12 BP 8931 EP 8937 DI 10.1063/1.462251 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA HZ098 UT WOS:A1992HZ09800030 ER PT J AU BROCK, JC MCCLAIN, CR HAY, WW AF BROCK, JC MCCLAIN, CR HAY, WW TI A SOUTHWEST MONSOON HYDROGRAPHIC CLIMATOLOGY FOR THE NORTHWESTERN ARABIAN SEA SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID OCEANOGRAPHY AB This paper provides a detailed hydrographic climatology for the shallow northwestern Arabian Sea prior to and during the southwest monsoon, presented as multiple-year composite vertical hydrographic sections based on National Oceanographic Data Center historical ocean station data. Temperature and salinity measurements are used to infer the water masses present in the upper 500 m. The hydrographic evolution depicted on bimonthly sections is inferred to result from wind-driven physical processes. In the northwestern Arabian Sea the water mass in the upper 50 m is the Arabian Sea Surface Water. Waters from 50 to 500 m are formed by mixing of Arabian Sea Surface Water with Antarctic and Indonesian intermediate waters. The inflow of Persian Gulf Water does not significantly influence the hydrography of the northwestern Arabian Sea along the Omani coast. Nitrate has a high inverse correlation with temperature and oxygen in the premonsoon thermocline in the depth interval 50-150 m. During the southwest monsoon, coastal upwelling off Oman and adjacent offshore upward Ekman pumping alter the shallow hydrography. C1 UNIV COLORADO,NOAA,COOPERAT INST RES ENVIRONM SCI,BOULDER,CO 80309. NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD 20771. NR 40 TC 35 Z9 35 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUN 15 PY 1992 VL 97 IS C6 BP 9455 EP 9465 DI 10.1029/92JC00813 PG 11 WC Oceanography SC Oceanography GA JA086 UT WOS:A1992JA08600007 ER PT J AU SCHACHAM, SE HAUGLAND, EJ ALTEROVITZ, SA AF SCHACHAM, SE HAUGLAND, EJ ALTEROVITZ, SA TI INTERMODULATION IN THE OSCILLATORY MAGNETORESISTANCE OF A 2-DIMENSIONAL ELECTRON-GAS SO PHYSICAL REVIEW B LA English DT Article ID QUANTUM WELLS; SCATTERING; HETEROSTRUCTURES; TRANSPORT; SYMMETRY AB The oscillatory magnetoresistance wave form of a two-dimensional electron gas shows multiple structures when two subbands are populated. In addition to high-field oscillations at a frequency equal to the sum of the two frequencies corresponding to the concentrations of the subbands, and to a superposition at intermediate fields, we observed oscillations at the difference frequency at low fields and higher temperatures. The field range at which the frequency difference is observed increases with increasing temperature. The crossover from superposition to frequency difference is accompanied by a beat. Similar beats, whose field location shows identical temperature dependence, can be observed in data obtained by other groups on different structures. The various components of the wave form can be attributed to different phase relations between the diagonal and off-diagonal elements of the conductivity tensor. It is shown how the intermodulation term, when inserted into the extended oscillatory equation, can give rise to all three structures. RP SCHACHAM, SE (reprint author), NASA,LEWIS RES CTR,M-S 54-5,CLEVELAND,OH 44135, USA. NR 11 TC 9 Z9 9 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD JUN 15 PY 1992 VL 45 IS 23 BP 13417 EP 13422 DI 10.1103/PhysRevB.45.13417 PG 6 WC Physics, Condensed Matter SC Physics GA HZ245 UT WOS:A1992HZ24500029 ER PT J AU SOZUER, HS HAUS, JW INGUVA, R AF SOZUER, HS HAUS, JW INGUVA, R TI PHOTONIC BANDS - CONVERGENCE PROBLEMS WITH THE PLANE-WAVE METHOD SO PHYSICAL REVIEW B LA English DT Article ID PERIODIC DIELECTRIC STRUCTURES; PROPAGATION; LOCALIZATION; MEDIA; GAP AB The problems associated with the poor convergence of the Fourier transform of the hard-sphere dielectric function are discussed. A significant band gap between the eighth and ninth levels has been found for air spheres in fcc. We also consider a periodic array of Gaussian spheres, which converges well and allows a consistent and reliable determination of the general features of photonic bands. It is found that when epsilon(r) is sharply peaked, photonic levels become almost degenerate throughout the Brillouin zone, corresponding to standing waves. C1 RENSSELAER POLYTECH INST,DEPT PHYS,TROY,NY 12180. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,OPT SYST BRANCH,HUNTSVILLE,AL 35812. RI Sozuer, Huseyin Sami/H-9552-2012 NR 22 TC 364 Z9 377 U1 3 U2 17 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD JUN 15 PY 1992 VL 45 IS 24 BP 13962 EP 13972 DI 10.1103/PhysRevB.45.13962 PG 11 WC Physics, Condensed Matter SC Physics GA JA212 UT WOS:A1992JA21200010 ER PT J AU KOLB, EW WANG, Y AF KOLB, EW WANG, Y TI DOMAIN-WALL FORMATION IN LATE-TIME PHASE-TRANSITIONS SO PHYSICAL REVIEW D LA English DT Article ID PSEUDO-GOLDSTONE BOSONS AB We investigate domain-wall formation in late-time phase transitions. We find that, as in the invisible-axion-domain-wall phenomenon, thermal effects alone are insufficient to drive different regions of the Universe to different parts of the disconnected vacuum manifold. This suggests that domain walls do not form unless either there is some supplemental (but perhaps not unreasonable) dynamics to localize the scalar field responsible for the phase transition to the low-temperature maximum (to an extraordinary precision) before the onset of the phase transition, or there is some nonthermal mechanism to produce large fluctuations in the scalar field. The fact that domain-wall production is not a robust prediction of late-time transitions may suggest future directions in model building. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV FLORIDA,DEPT PHYS,GAINESVILLE,FL 32611. RP KOLB, EW (reprint author), UNIV CALIF SANTA BARBARA,INST THEORET PHYS,SANTA BARBARA,CA 93106, USA. RI Wang, Yun/B-5724-2011 OI Wang, Yun/0000-0002-4749-2984 NR 10 TC 13 Z9 13 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD JUN 15 PY 1992 VL 45 IS 12 BP 4421 EP 4427 DI 10.1103/PhysRevD.45.4421 PG 7 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA HZ562 UT WOS:A1992HZ56200010 ER PT J AU KOSOWSKY, A TURNER, MS WATKINS, R AF KOSOWSKY, A TURNER, MS WATKINS, R TI GRAVITATIONAL-RADIATION FROM COLLIDING VACUUM BUBBLES SO PHYSICAL REVIEW D LA English DT Article ID EXTENDED INFLATION; FALSE VACUUM; UNIVERSE; STRINGS; FATE AB In the linearized-gravity approximation we numerically compute the amount of gravitational radiation produced by the collision of two true-vacuum bubbles in Minkowski space. The bubbles are separated by distance d and we calculate the amount of gravitational radiation that is produced in a time tau approximately d (in a cosmological phase transition tau-corresponds to the duration of the transition, which is expected to be of the order of the mean bubble separation d). Our approximations are generally valid for tau less-than-or-similar-to H-1. We find that the amount of gravitational radiation produced depends only upon the grosset features of the collision: the time tau and the energy density associated with the false-vacuum state, rho(vac). In particular, the spectrum dE(GW)/d-omega is-proportional-to rho(vac)2-tau(6) and peaks at a characteristic frequency omega(max) congruent-to 3.8/tau, and the fraction of the vacuum energy released into gravitational waves is about 1.3 x 10(-3) (tau/H-1)2, where H-2 = 8-pi-G-rho(vac)/3 (tau/H-1 is expected to be of the order of a few percent). We address in some detail the important symmetry issues in the problem, and how the familiar "quadrupole approximation" breaks down in a most unusual way: it overestimates the amount of gravitational radiation produced in this highly relativistic situation by more than a factor of 50. Most of our results are for collisions of bubbles of equal size, though we briefly consider the collision of vacuum bubbles of unequal size. Our work implies that the vacuum-bubble collisions associated with a strongly first-order phase transition are a very potent cosmological source of gravitational radiation. C1 UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP KOSOWSKY, A (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510, USA. NR 31 TC 133 Z9 133 U1 1 U2 2 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 JUN 15 PY 1992 VL 45 IS 12 BP 4514 EP 4535 DI 10.1103/PhysRevD.45.4514 PG 22 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA HZ562 UT WOS:A1992HZ56200018 ER PT J AU WHITTENBERGER, JD ARZT, E LUTON, MJ AF WHITTENBERGER, JD ARZT, E LUTON, MJ TI 1400-K AND 1500-K COMPRESSIVE CREEP-PROPERTIES OF AN NIAL-ALN COMPOSITE SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 MAX PLANCK INST MET RES,W-7000 STUTTGART 80,GERMANY. EXXON RES & ENGN CO,RES & ENGN,ANNANDALE,NJ 08801. RP WHITTENBERGER, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Arzt, Eduard/B-5282-2008 NR 7 TC 10 Z9 10 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD JUN 15 PY 1992 VL 26 IS 12 BP 1925 EP 1930 DI 10.1016/0956-716X(92)90060-R PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA HW367 UT WOS:A1992HW36700025 ER PT J AU DICKEY, JO MARCUS, SL HIDE, R AF DICKEY, JO MARCUS, SL HIDE, R TI GLOBAL PROPAGATION OF INTERANNUAL FLUCTUATIONS IN ATMOSPHERIC ANGULAR-MOMENTUM SO NATURE LA English DT Article AB THE El Nino Southern Oscillation (ENSO), a climate fluctuation that recurs on a 2-7-yr timescale, is associated with persistent large-scale fluctuations in the dynamical behaviour of the global atmosphere-ocean system 1. Here we present a study of the latitudinal redistribution of angular momentum within the atmosphere from 1976 to 1991. We observe slow, global-scale coherent poleward propagation of atmospheric angular-momentum fluctuations on interannual timescales. These originate in equatorial regions, where they lead the main atmospheric anomalies of the ENSO cycle by nearly two years; they penetrate to latitudes higher than 60-degrees in both hemispheres, where they lag behind the ENSO cycle by about four years. We can also distinguish the bimodality of the ENSO phenomenon, with a low-frequency component centred at a period close to 4.2 years and a high-frequency component centred near 2.4 years. Each of the two components has a distinct latitudinal propagation pattern. In the period studied, strong El Nino and related La Nina climatic events occur when these components add constructively. C1 CLARENDON LAB OBSERV,ROBERT HOOKE INST,METEOROL OFF UNIT,OXFORD OX1 3PU,ENGLAND. RP DICKEY, JO (reprint author), JET PROP LAB,SPACE GEODET SCI & APPLICAT GRP,4800 OAK GROVE DR,PASADENA,CA 91109, USA. OI Marcus, Steven/0000-0002-5763-6961 NR 18 TC 72 Z9 77 U1 0 U2 2 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUN 11 PY 1992 VL 357 IS 6378 BP 484 EP 488 DI 10.1038/357484a0 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HY052 UT WOS:A1992HY05200058 ER PT J AU KOUVELIOTOU, C NORRIS, JP WOOD, KS CLINE, TL DENNIS, BR DESAI, UD ORWIG, LE AF KOUVELIOTOU, C NORRIS, JP WOOD, KS CLINE, TL DENNIS, BR DESAI, UD ORWIG, LE TI SEARCH FOR SOFT GAMMA-REPEATERS IN THE SMM HXRBS DATA SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, BURSTS; GAMMA RAYS, OBSERVATIONS ID HIGH-ENERGY TRANSIENT; RAY BURST AB Bursts from the soft gamma-ray repeaters (SGRs) appear to constitute a class of high-energy transients separate from typical gamma-ray bursts. Their distinct characteristics include stochastic burst repetition, short (approximately 0.1 s) durations, simple time histories, rise times as fast as 5 ms, spectra with characteristic energies of approximately 30 keV, and no indication of spectral evolution on time scales as short as approximately 0.1 s. Presently, only three repeaters are known. Thus, fundamental questions regarding their typical active lifetimes, celestial distribution, and luminosity function remain unresolved. We describe the results of a search for short transients resembling SGR bursts using the triggered fast memory of the hard X-ray burst spectrometer (HXRBS) on board the Solar Maximum Mission (SMM). This instrument operated for almost 10 years, from its launch in 1980 February until its demise in 1989 December. Each year its 40-degrees FWHM field of view scanned approximately one-quarter of the sky in the form of a band about 80-degrees wide centered on the ecliptic. HXRBS had a unique triggering capability with very short integration times of 4, 32, and 256 ms that made it ideal for detecting short, intense events. The effective HXRBS sensitivity for detecting SGR-like bursts longer than approximately 20 ms was routinely approximately 4 x 10(-7) ergs cm-2, and occasionally 8 x 10(-8) ergs cm-2. This search adds to the coverage by the International Cometary Explorer (ICE) of the most active repeater, SGR 1806-20, and indicates that the highly active phase of this source has not continued beyond 1984. We have found no other SGR-like source, but we identify some candidate events. Our results, combined with results from ICE and Konus observations and the assumption of a neutron star origin, enable us to make estimates of the burst-active time of an SGR source. In addition, we calculate the noise environment of the HXRBS CsI(Na) crystal on board SMM, a spacecraft in a low-inclination/low-altitude orbit, to be 1.5 x 10(-4) events s-1. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. USN,RES LAB,WASHINGTON,DC 20375. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV ATHENS,DEPT PHYS,ATHENS,GREECE. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RI Dennis, Brian/C-9511-2012 NR 20 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1992 VL 392 IS 1 BP 179 EP 186 DI 10.1086/171416 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY143 UT WOS:A1992HY14300019 ER PT J AU CANUTO, VM AF CANUTO, VM TI TURBULENT CONVECTION WITH OVERSHOOTING - REYNOLDS STRESS APPROACH SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; CONVECTION; STARS, INTERIORS; TURBULENCE ID PLANETARY BOUNDARY-LAYER; NUMERICAL-SIMULATION; SHEAR FLOWS; HEAT-FLUX; MODEL; CLOSURE; TRANSPORT; EQUATIONS; INVERSION; PROGRESS AB Turbulent convection is a phenomenon relevant to both stellar structure and accretion disks. In the latter, a basic parameter such as the turbulent viscosity nu(t) is still treated phenomenologically; in the case of stellar structure, most of the work still relies on the mixing-length theory (MLT) which assumes homogeneity and thus lacks diffusion terms (divergence of third-order moments like w2-thetaBAR, w-theta-2BAR, q 2wBAR). To include them, one needs a new formalism. We review and discuss the Reynolds stress approach (proven successful in other fields) which provides a set of coupled differential equations that yield all the turbulent quantities of interest. Although the system can only be solved numerically, some features can be listed: 1. The convective flux F(c) = c(p)rho-w-thetaBAR is not given simply by (kappa(t) is the turbulent conductivity) F(c) = F(c)MLT almost-equal-to kappa(t)(del - del(ad)). 2. Inclusion of the diffusion terms related to w2-thetaBAR and w-theta-2BAR contributes a countergradient term GAMMA(c), which may carry heat from cold to hot regions, F(c) almost-equal-to kappa(t)(del - del(ad) + GAMMA(c)). The term GAMMA(c) was first discussed by Deardorff in the context of atmospheric turbulence. 3. Inclusion of the diffusion term related to 1/2q2wBAR (turbulent kinetic energy flux) contributes an additional term (first discussed in atmospheric turbulence by Tennekes) F(c) almost-equal-to kappa(t)(del - del(ad) + GAMMA(c)) + F(c)diff, which is responsible for overshooting. In addition to the convective flux, we also derive a model expression for nu(t) as a function of both shear and buoyency: it is needed in the numerical simulation of stellar convection and in accretion disks to replace the phenomenological expressions used thus far. RP CANUTO, VM (reprint author), NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. NR 69 TC 88 Z9 89 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 JUN 10 PY 1992 VL 392 IS 1 BP 218 EP 232 DI 10.1086/171420 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY143 UT WOS:A1992HY14300023 ER PT J AU DAVIDSEN, AF LONG, KS DURRANCE, ST BLAIR, WP BOWERS, CW CONARD, SJ FELDMAN, PD FERGUSON, HC FOUNTAIN, GH KIMBLE, RA KRISS, GA MOOS, HW POTOCKI, KA AF DAVIDSEN, AF LONG, KS DURRANCE, ST BLAIR, WP BOWERS, CW CONARD, SJ FELDMAN, PD FERGUSON, HC FOUNTAIN, GH KIMBLE, RA KRISS, GA MOOS, HW POTOCKI, KA TI THE HOPKINS ULTRAVIOLET TELESCOPE - PERFORMANCE AND CALIBRATION DURING THE ASTRO-1 MISSION SO ASTROPHYSICAL JOURNAL LA English DT Article DE ARTIFICIAL SATELLITES, SPACE PROBES; INSTRUMENTATION, SPECTROGRAPHS; STARS, INDIVIDUAL (G191-B2B); ULTRAVIOLET, GENERAL; WHITE DWARFS ID HOT STARS; SPECTROPHOTOMETRY; INSTRUMENTATION; FLUX AB The Hopkins Ultraviolet Telescope (HUT) was flown aboard the Space Shuttle Columbia on the Astro-1 mission 1990 December 2-11. Spectrophotometric observations of 77 astronomical sources were made throughout the far-ultraviolet (912-1850 angstrom) at a resolution of approximately 3 angstrom, and, for a small number of sources, in the extreme ultraviolet (415-912 angstrom) beyond the Lyman limit at a resolution of approximately 1.5 angstrom. The objects observed include quasars, galaxy clusters, active and normal galaxies, cataclysmic variables, globular clusters, supernova remnants, planetary nebulae, white dwarfs, Wolf-Rayet stars, Be stars, cool stars with active coronae, comet Levy (1990c), Jupiter, and Io. HUT has provided the first spectrophotometry in the sub-Lyman-alpha region for most of these sources. In this paper we describe the HUT instrument and its performance in orbit. We also present a HUT observation of the DA white dwarf G191-B2B and derive the photometric calibration curve for the instrument from a comparison of the observation with a model stellar atmosphere. The sensitivity reaches a maximum at 1050 angstrom, where 1 photon cm-2 s-1 angstrom-1 yields 9.5 counts s-1 angstrom-1, and remains within a factor 2 of this value from 912 to 1600 angstrom. The instrumental dark count measured on orbit was less than 10(-3) counts s-1 angstrom-1. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV CAMBRIDGE OBSERV,INST ASTRON,CAMBRIDGE CB3 0HA,ENGLAND. JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20723. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP DAVIDSEN, AF (reprint author), JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,CHARLES & 34TH ST,BALTIMORE,MD 21218, USA. NR 27 TC 111 Z9 111 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1992 VL 392 IS 1 BP 264 EP 271 DI 10.1086/171424 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY143 UT WOS:A1992HY14300027 ER PT J AU POTGIETER, MS LEROUX, JA AF POTGIETER, MS LEROUX, JA TI THE SIMULATED FEATURES OF HELIOSPHERIC COSMIC-RAY MODULATION WITH A TIME-DEPENDENT DRIFT MODEL .3. GENERAL ENERGY-DEPENDENCE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCELERATION OF PARTICLES; COSMIC RAYS; INTERPLANETARY MEDIUM; SUN, ACTIVITY ID NEUTRAL SHEET DRIFT; SOLAR MODULATION; MAGNETIC-FIELD; TRANSPORT; DIFFUSION AB The time-dependent cosmic-ray transport equation is solved numerically in an axially symmetric heliosphere. Gradient and curvature drifts are incorporated, together with an emulated wavy neutral sheet. This model is used to simulate heliospheric cosmic-ray modulation for the period 1985-1989 during which drifts are considered to be important. The general energy dependence of the modulation of Galactic protons is studied as predicted by the model for the energy range 1 MeV to 10 GeV. The corresponding instantaneous radial and latitudinal gradients are calculated, and it is found that whereas the latitudinal gradients follow the trends in the waviness of the neutral sheet to a large extent for all energies, the radial gradients below approximately 200 MeV deviate from this general pattern. In particular, these gradients increase when the waviness decreases for the simulated period 1985-1987.3, after which they again follow the neutral sheet by increasing rapidly. These results illustrate the full consequences of time-dependent modulation where all four major modulation mechanisms, convection, diffusion, drifts and adiabatic energy losses, are considered. C1 UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. NR 43 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1992 VL 392 IS 1 BP 300 EP 309 DI 10.1086/171429 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY143 UT WOS:A1992HY14300032 ER PT J AU FINESCHI, S DEGL'INNOCENTI, EL AF FINESCHI, S DEGL'INNOCENTI, EL TI ELECTRON-IMPACT POLARIZATION OF ATOMIC SPECTRAL-LINES .1. A GENERAL THEORETICAL SCHEME SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; LINE, FORMATION; POLARIZATION ID SOLAR-FLARES; HYDROGEN AB A suitable theoretical scheme able to describe, in a wide variety of astrophysical situations, the phenomenon of atomic line polarization by electron impact is developed. Starting from the general principles of quantum mechanics and assuming the Born approximation, the rate equations for the density matrix elements of a multilevel atomic system, interacting with a nonrelativistic electron beam having any kind of angular distribution, are derived in full generality. The resulting theory generalizes the previous ones by accounting for the collisional rates and the cross sections concerning both inelastic and superelastic collisions (in any geometrical situation), and-moreover-by taking into account the coherences among Zeeman sublevels split by a magnetic field. The final equations for the collisional rates are made quite compact by the introduction of suitable spherical tensors connected with the components of the electric multipole moments of the atomic transitions. As an example of particular relevance, the general formulae derived in the first sections of the paper are subsequently particularized to the case of the electric di ole interaction. C1 NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. UNIV FLORENCE, DIPARTIMENTO ASTRON & SCI SPAZIO, I-50125 FLORENCE, ITALY. NR 33 TC 7 Z9 7 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1992 VL 392 IS 1 BP 337 EP 352 DI 10.1086/171433 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY143 UT WOS:A1992HY14300036 ER PT J AU WILKINSON, LK EMSLIE, AG GARY, GA AF WILKINSON, LK EMSLIE, AG GARY, GA TI ON NEUTRALIZED CURRENTS IN THE SOLAR CORONA SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; SUN, CORONA; SUN, MAGNETIC FIELDS; SUNSPOTS ID MAGNETIC-FIELDS AB Using Ampere's integral law applied to vector magnetograph transverse field data, we have analyzed the current pattern in an active region associated with flaring activity. The greater sensitivity of this integral (rather than differential) formalism of Ampere's law may allow one to identify regions of weak return current around the actual positive current region. The effects of Faraday rotation on the inferred magnetic field measurements, and hence on the deduced current pattern, are discussed. It is concluded that the current patterns in the region consist either of a neutralized (return) current system, well modeled by a coaxial cable, or of a potential (current-free) field, with the apparent currents in the core an artifact induced by magneto-optical effects. In either case, the data do not convincingly show an unneutralized current system. C1 UNIV ALABAMA,HUNTSVILLE,AL 35899. RP WILKINSON, LK (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 13 TC 15 Z9 15 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1992 VL 392 IS 1 BP L39 EP L42 DI 10.1086/186420 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY144 UT WOS:A1992HY14400010 ER PT J AU ARCHER, FA STREET, KW AF ARCHER, FA STREET, KW TI SPECTROPHOTOMETRIC DETERMINATION OF SILICON IN BISMUTH BOROSILICATE GLASS BY FLOW-INJECTION SO ANALYTICA CHIMICA ACTA LA English DT Article DE FLOW SYSTEM; SPECTROPHOTOMETRY; BISMUTH; BOROSILICATE GLASS; SILICON ID COLUMN; SYSTEM; ACID AB A spectrophotometric flow-injection method for the determination of silicate based on heteropoly blue formation is presented. The proposed reagent gives a wider dynamic range than previously reported flow-injection procedures. The bismuth interference reported for the spectrophotometric method is eliminated in sample preparation and the method is applied to the determination of silicon in bismuth borosilicate glass. Results are compared to spectrophotometric and inductively coupled argon plasma emission spectrometric determinations. C1 CLEVELAND STATE UNIV,DEPT CHEM,CLEVELAND,OH 44115. RP ARCHER, FA (reprint author), NASA,LEWIS RES CTR,MAIL STOP 105-1,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 32 TC 3 Z9 3 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0003-2670 J9 ANAL CHIM ACTA JI Anal. Chim. Acta PD JUN 5 PY 1992 VL 262 IS 2 BP 243 EP 251 DI 10.1016/0003-2670(92)80061-B PG 9 WC Chemistry, Analytical SC Chemistry GA HZ519 UT WOS:A1992HZ51900006 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR AF BAUSCHLICHER, CW LANGHOFF, SR TI THEORETICAL-STUDY OF THE BOND-DISSOCIATION ENERGIES OF PROPYNE (C3H4) SO CHEMICAL PHYSICS LETTERS LA English DT Article ID ELECTRON CORRELATION; BASIS SETS; ISOMERIZATION; ABINITIO; CONTRACTION; ACETYLENE; ALLENE; CI(SD); ATOMS AB The C-C and C-H bond dissociation energies (BDEs) of propyne have been computed using the modified coupled-pair functional method. Due to hyperconjugation, the C-C and methyl C-H single bonds are stronger and weaker, respectively, than those in ethane. The acetylenic C-H and C=C BDEs are larger and smaller, respectively, than in acetylene, also as a result of the hyperconjugation. Our best estimate of 92.5 +/- 2 kcal/mol for the methyl C-H BDE in propyne in slightly larger than the experimental value. For the acetylenic C-H BDE in propyne we predict 135.9 +/- 2 kcal/mol. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 33 TC 29 Z9 29 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUN 5 PY 1992 VL 193 IS 5 BP 380 EP 385 DI 10.1016/0009-2614(92)85646-R PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA HY492 UT WOS:A1992HY49200012 ER PT J AU LIU, J KIM, J KWATRA, SC STEVENS, GH AF LIU, J KIM, J KWATRA, SC STEVENS, GH TI ROTATIVE QUADRATURE PHASE-SHIFT KEYING SO ELECTRONICS LETTERS LA English DT Article DE MODULATION; QUADRATURE PHASE-SHIFT KEYING AB A rotative quadrature phase-shift keying (RQPSK) modulation scheme is proposed. By rotating the QPSK signal constellation by pi/2 either clockwise or anticlockwise during a symbol duration, the conventional QPSK scheme can be modified to transmit 3 bits per symbol to achieve both power and bandwidth efficiency. C1 UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 1 TC 4 Z9 4 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD JUN 4 PY 1992 VL 28 IS 12 BP 1095 EP 1097 DI 10.1049/el:19920692 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA HY581 UT WOS:A1992HY58100012 ER PT J AU SIMONS, RN TAUB, SR AF SIMONS, RN TAUB, SR TI NEW COPLANAR WAVE-GUIDE TO RECTANGULAR WAVE-GUIDE END LAUNCHER SO ELECTRONICS LETTERS LA English DT Article DE WAVE-GUIDE COUPLERS AB A new coplanar waveguide to rectangular waveguide end launcher is experimentally demonstrated. The end launcher operates over the K(a)-band frequencies that are designated for the NASA Advanced Communication Technology Satellite (ACTS) uplink. The measured insertion loss and return loss are better than 0.5 and -10 dB, respectively. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,MAIL STOP 54-5,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 3 TC 5 Z9 5 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD JUN 4 PY 1992 VL 28 IS 12 BP 1138 EP 1139 DI 10.1049/el:19920717 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA HY581 UT WOS:A1992HY58100037 ER PT J AU HARDING, AK LEVENTHAL, M AF HARDING, AK LEVENTHAL, M TI CAN ACCRETION ONTO ISOLATED NEUTRON-STARS PRODUCE GAMMA-RAY BURSTS SO NATURE LA English DT Article ID BINARY-SYSTEMS; ORIGIN AB THE isotropy and flat count spectrum of gamma-ray bursts revealed by the BATSE detector on the Compton Gamma-Ray Observatory 1 have led to suggestions that the burst sources are an extended galactic halo of high-velocity neutron stars 2,3. We show here that if slow accretion onto these neutron stars from the interstellar medium is to be the origin of gamma-ray bursts, the accretion physics is very different from what applies for local, low-velocity neutron stars 4,5. For halo neutron stars with high magnetic fields and velocities (upsilon > 190 km s-1), electromagnetic dipole radiation pressure prevents accretion unless the period is longer than tens of seconds; the centrifugal barrier will then prevent accretion until the period reaches several thousand seconds. For periods as long as this, accretion may proceed through Kelvin-Helmholtz instability at the magnetopause boundary. At interstellar densities and neutron-star magnetic fields of approximately 10(12) G, the accretion rate by this process can be much larger than the Bondi-Hoyle (hydrodynamic) accretion rate, but is still well below what is needed for slow-accretion burst models. We conclude that slow accretion onto high-velocity neutron stars in the halo cannot be the origin of gamma-ray bursts. 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 23 TC 20 Z9 20 U1 0 U2 1 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUN 4 PY 1992 VL 357 IS 6377 BP 388 EP 389 DI 10.1038/357388a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HX172 UT WOS:A1992HX17200055 ER PT J AU NOOR, AK ANDERSEN, CM AF NOOR, AK ANDERSEN, CM TI HYBRID ANALYTICAL TECHNIQUE FOR THE NONLINEAR-ANALYSIS OF CURVED BEAMS SO COMPUTERS & STRUCTURES LA English DT Article ID GALERKIN TECHNIQUE; THERMAL-ANALYSIS; EXPANSIONS; SERIES AB The application of a two-step hybrid technique to the geometrically nonlinear analysis of curved beams is used to demonstrate the potential of hybrid analytical techniques in nonlinear structural mechanics. The hybrid technique is based on successive use of the perturbation method and a classical direct variational procedure. The functions associated with the various-order terms in the perturbation expansion of the fundamental unknowns, and their sensitivity derivatives with respect to material and geometric parameters of the beam, are first obtained by using the perturbation method. These functions are selected as coordinate functions (or modes) and the classical direct variational technique is then used to compute their amplitudes. The potential of the proposed hybrid technique for nonlinear analysis of structures is discussed. The effectiveness of the hybrid technique is demonstrated by means of numerical examples. The symbolic computation system Mathematica is used in the present study. The tasks performed on Mathematica include: (1) generation of algebraic expressions for the perturbation functions of the different response quantities and their sensitivity derivatives; and (2) determination of the radius of convergence of the perturbation series. C1 COLL WILLIAM & MARY,WILLIAMSBURG,VA 23185. RP NOOR, AK (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR COMPUTAT STRUCT TECHNOL,HAMPTON,VA 23665, USA. NR 15 TC 2 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD JUN 3 PY 1992 VL 43 IS 5 BP 823 EP 830 DI 10.1016/0045-7949(92)90296-C PG 8 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA JD014 UT WOS:A1992JD01400002 ER PT J AU BACMEISTER, JT SCHOEBERL, MR LOEWENSTEIN, M PODOLSKE, JR STRAHAN, SE CHAN, KR AF BACMEISTER, JT SCHOEBERL, MR LOEWENSTEIN, M PODOLSKE, JR STRAHAN, SE CHAN, KR TI AN ESTIMATE OF THE RELATIVE MAGNITUDE OF SMALL-SCALE TRACER FLUXES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERE; TRANSPORT; OZONE AB The wind and constituent measurements from the polar aircraft data are used to compute the flux spectra. Although there is variation from flight to flight, the flux spectra generally fit a -2 to -1.5 power law as expected theoretically. This result suggests that tracer fluxes from small scale features do not substantially contribute to the overall tracer budget relative to the fluxes from the larger scales. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BACMEISTER, JT (reprint author), USN,RES LAB,CODE 4141,WASHINGTON,DC 20375, USA. RI Strahan, Susan/H-1965-2012 NR 13 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 2 PY 1992 VL 19 IS 11 BP 1101 EP 1104 DI 10.1029/92GL01039 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HX652 UT WOS:A1992HX65200009 ER PT J AU GRANT, WB FISHMAN, J BROWELL, EV BRACKETT, VG NGANGA, D MINGA, A CROS, B VEIGA, RE BUTLER, CF FENN, MA NOWICKI, GD AF GRANT, WB FISHMAN, J BROWELL, EV BRACKETT, VG NGANGA, D MINGA, A CROS, B VEIGA, RE BUTLER, CF FENN, MA NOWICKI, GD TI OBSERVATIONS OF REDUCED OZONE CONCENTRATIONS IN THE TROPICAL STRATOSPHERE AFTER THE ERUPTION OF MT PINATUBO SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HETEROGENEOUS CHEMISTRY; EL-CHICHON AB The eruption of Mt. Pinatubo (15-degrees-N, 122-degrees-E) on June 15 and 16, 1991, placed a large amount of SO2 and crustal material in the stratosphere. Based on measurements of decreases of stratospheric ozone after previous volcanic eruptions, it was expected that the aerosols deposited into the stratosphere (both directly and as a result of SO2 conversion into particulate sulfate) by this eruption would give rise to significant ozone depletions. To check for such an effect, ozone profiles obtained from ECC sondes before and after the eruption at Brazzaville, Congo (4-degrees-S, 15-degrees-E), and Ascension Island (8-degrees-S, 14-degrees-W), are examined. Aerosol profiles determined from a lidar system in the western Pacific (4-degrees-6-degrees-N, 125-degrees-E) show that most of the material injected into the stratosphere is located between 18 and 28 km with highest amounts at 24-25 km. For the period 3-6 months after the eruption, decreases in ozone are found at 16 to 29 km, with peak decreases as large as 20% found at 24 km. Integrated between 16 and 28 km, a decrease of 13-20 Dobson units is observed when the ozonesonde data after the Pinatubo eruption are compared with those prior to the eruption. The altitude at which the most pronounced ozone decrease is found strongly correlates with peak aerosol loading determined by the lidar. In addition, a small increase in ozone density is found above about 28 km. Mechanisms that might explain the results such as heterogeneous chemistry, radiative effects, and dynamics are discussed. C1 UNIV MAIEN NGOUABI,BRAZZAVILLE,CONGO PEOPL REP. SCI APPLICAT INT CORP,HAMPTON,VA 23666. RP GRANT, WB (reprint author), NASA,LANGLEY RES CTR,MS 401A,HAMPTON,VA 23665, USA. RI Grant, William/B-8311-2009 OI Grant, William/0000-0002-1439-3285 NR 27 TC 61 Z9 61 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 2 PY 1992 VL 19 IS 11 BP 1109 EP 1112 DI 10.1029/92GL01153 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HX652 UT WOS:A1992HX65200011 ER PT J AU HANSON, RJ KROGH, FT AF HANSON, RJ KROGH, FT TI A QUADRATIC-TENSOR MODEL ALGORITHM FOR NONLINEAR LEAST-SQUARES PROBLEMS WITH LINEAR CONSTRAINTS SO ACM TRANSACTIONS ON MATHEMATICAL SOFTWARE LA English DT Article DE ALGORITHMS; CONSTRAINED LEAST SQUARES; NONLINEAR LEAST-SQUARES ID OPTIMIZATION; EQUATIONS AB A new algorithm is presented for solving nonlinear least-squares and nonlinear equation problems. The algorithm is based on approximating the nonlinear functions using the quadratic-tensor model proposed by Schnabel and Frank. The problem statement may include simple bounds or more general linear constraints on the unknowns. The algorithm uses a trust-region defined by a box containing the current values of the unknowns. The objective function (Euclidean length of the functions) is allowed to increase at intermediate steps. These increases are allowed as long as our predictor indicates that a new set of best values exists in the trust-region. There is logic provided to retreat to the current best values, should that be required. The computations for the model-problem require a constrained nonlinear least-squares solver. This is done using a simpler version of the algorithm. In its present form the algorithm is effective for problems with linear constraints and dense Jacobian matrices. Results on standard test problems are presented in the Appendix. The new algorithm appears to be efficient in terms of function and Jacobian evaluations. C1 JET PROP LAB,PASADENA,CA 91109. RP HANSON, RJ (reprint author), IMSL INC,14141 SW FREEWAY,SUGAR LAND,TX 77478, USA. NR 24 TC 10 Z9 10 U1 1 U2 3 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0098-3500 J9 ACM T MATH SOFTWARE JI ACM Trans. Math. Softw. PD JUN PY 1992 VL 18 IS 2 BP 115 EP 133 DI 10.1145/146847.146857 PG 19 WC Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA LQ591 UT WOS:A1992LQ59100001 ER PT J AU NICOGOSSIAN, AE GAISER, KK AF NICOGOSSIAN, AE GAISER, KK TI THE SPACE LIFE SCIENCES STRATEGY FOR THE 21ST-CENTURY SO ACTA ASTRONAUTICA LA English DT Note AB In the past, space life sciences has focused on gaining an understanding of physiological tolerance to spaceflight, but, for the last 10 years, the focus has evolved to include issues relevant to extended duration missions. In the 21st century, NASA's long-term strategy for the exploration of the solar system will combine the assurance of human health and performance for long periods in space with investigations aimed at searching for traces of life on other planets and acquiring fundamental scientific knowledge of life processes. Implementation of this strategy will involve a variety of disciplines including radiation health, life support, human factors, space physiology and countermeasures, medical care, environmental health, and exobiology. It will use both ground-based and flight research opportunities such as those found in current on-going programs, on Spacelab and unmanned biosatellite flights, and during Space Station Freedom missions. RP NICOGOSSIAN, AE (reprint author), NASA HEADQUARTERS,DIV LIFE SCI,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUN PY 1992 VL 26 IS 6 BP 459 EP 465 DI 10.1016/0094-5765(92)90074-S PG 7 WC Engineering, Aerospace SC Engineering GA JJ943 UT WOS:A1992JJ94300007 PM 11537564 ER PT J AU HORSTMAN, CC AF HORSTMAN, CC TI HYPERSONIC SHOCK-WAVE TURBULENT-BOUNDARY-LAYER INTERACTION FLOWS SO AIAA JOURNAL LA English DT Article AB THIS paper uses a two-dimensional/axisymmetric Navier-Stokes code to study the accuracy of the two-equation k-epsilon-turbulence model 1 when compared with the hypersonic shock-wave/boundary-layer interaction data base. 2 Two modifications of the standard k-epsilon-model are also investigated. The first is the new two-layer k-epsilon-model developed by Rodi 3 that has had good success for separated flows at low speeds. The second is a modification developed to account for compressibility effects following the work of Rubesin 4 and Vuong and Coakley. 5 These three models are evaluated by comparison with the data. The relative merits of the modifications are discussed. RP HORSTMAN, CC (reprint author), NASA,AMES RES CTR,DIV FLUID DYNAM,MAIL STOP 229-1,MOFFETT FIELD,CA 94035, USA. NR 5 TC 3 Z9 3 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1992 VL 30 IS 6 BP 1480 EP 1481 DI 10.2514/3.11089 PG 2 WC Engineering, Aerospace SC Engineering GA HX732 UT WOS:A1992HX73200004 ER PT J AU FAROKHI, S TAGHAVI, R RICE, EJ AF FAROKHI, S TAGHAVI, R RICE, EJ TI MODERN DEVELOPMENTS IN SHEAR-FLOW CONTROL WITH SWIRL SO AIAA JOURNAL LA English DT Article AB EXCITABILITY of a turbulent swirling round jet is explored both qualitatively and quantitatively in the subsonic regime. Plane-wave acoustic excitation as the forcing mechanism caused periodic coherent vortical structures to appear in the shear layer, very close to the nozzle lip. Spectra of the hot-wire measurements along the jet axis reveal the growth of the fundamental wave and no amplification of a subharmonic. Vortex pairing as a mechanism for jet spread in the near field is hence ruled out for turbulent swirling jets. At large forcing amplitudes, a 10% reduction of the mean center-line velocity at nine nozzle diameters, and a corresponding increase in the shear-layer momentum thickness, are measured. It is remarkable to achieve this level of mixing enhancement in a rotating jet by an axisymmetric excitation, while the jet's "preferred" mode is of helical nature corresponding to Taylor-Gortler instability waves. C1 NASA,LEWIS RES CTR,INLETS & NOZZLES FLOW PHYS BRANCH,CLEVELAND,OH 44135. RP FAROKHI, S (reprint author), UNIV KANSAS,DEPT AEROSP ENGN,FLIGHT RES LAB,LAWRENCE,KS 66045, USA. NR 4 TC 7 Z9 7 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1992 VL 30 IS 6 BP 1482 EP 1483 DI 10.2514/3.11090 PG 2 WC Engineering, Aerospace SC Engineering GA HX732 UT WOS:A1992HX73200005 ER PT J AU ZAMAN, KBMQ AF ZAMAN, KBMQ TI EFFECT OF ACOUSTIC EXCITATION ON STALLED FLOWS OVER AN AIRFOIL SO AIAA JOURNAL LA English DT Article ID SEPARATION AB The effect of acoustic excitation on poststalled flows over an airfoil, i.e., flows that are fully separated from near the leading edge, is investigated. The excitation results in a tendency toward reattachment, which is accompanied by an increased lift and reduced drag, although the flow may still remain fully separated. It is found that, with increasing excitation amplitude, the effect becomes more pronounced but shifts to a Strouhal number that is much lower than that expected from linear, inviscid instability of the separated shear layer. RP ZAMAN, KBMQ (reprint author), NASA,LEWIS RES CTR,MAIL STOP 5-11,CLEVELAND,OH 44135, USA. NR 18 TC 35 Z9 40 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1992 VL 30 IS 6 BP 1492 EP 1499 DI 10.2514/3.11092 PG 8 WC Engineering, Aerospace SC Engineering GA HX732 UT WOS:A1992HX73200007 ER PT J AU SHIH, TH CHEN, JY LUMLEY, JL AF SHIH, TH CHEN, JY LUMLEY, JL TI 2ND-ORDER MODELING OF BOUNDARY-FREE TURBULENT SHEAR FLOWS SO AIAA JOURNAL LA English DT Article AB This paper presents a set of realizable second-order models for boundary-free turbulent flows. The constraints on second-order models based on the realizability principle are re-examined. The rapid terms in the pressure correlations for both the Reynolds stress and the passive scalar flux equations are constructed to exactly satisfy the joint realizability. All other model terms (return to isotropy, third moments, and terms in the dissipation equations) already satisfy realizability. To correct the spreading rate of the axisymmetric jet, an extra term is added to the dissipation equation, which accounts for the effect of mean vortex stretching on dissipation. The test flows used in this study are the mixing shear layer, plane jet, axisymmetric jet, and plane wake. The numerical solutions show that the new unified model equations (with unchanged model constants) predict all of these flows reasonably as the results compare well with the measurements. We expect that these model equations would be suitable for more complex and critical flows. C1 UNIV CALIF BERKELEY,DEPT MECH ENGN,BERKELEY,CA 94720. CORNELL UNIV,SIBLEY SCH MECH & AEROSP ENGN,ITHACA,NY 14853. RP SHIH, TH (reprint author), NASA,LEWIS RES CTR,CTR MODELING TURBULENCE & TRANSIT,CLEVELAND,OH 44135, USA. NR 27 TC 7 Z9 7 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1992 VL 30 IS 6 BP 1553 EP 1560 DI 10.2514/3.11100 PG 8 WC Engineering, Aerospace SC Engineering GA HX732 UT WOS:A1992HX73200015 ER PT J AU HUNG, CM SUNG, CH CHEN, CL AF HUNG, CM SUNG, CH CHEN, CL TI COMPUTATION OF SADDLE-POINT OF ATTACHMENT SO AIAA JOURNAL LA English DT Article ID BOUNDARY-LAYER INTERACTION; INDUCED SHOCK-WAVE; TURBULENT AB Because of its reputed benign nature, the saddle point of attachment has not received critical attention to nearly the same extent as has the saddle point of separation. Recently, Visbal calculated low-speed flows around a cylinder mounted on a flat plate. Here, it was fully to be expected that the outermost critical point in the surface flow pattern ahead of the obstacle would be a saddle point of separation. The results indicated that the critical point was actually a saddle point of attachment, not separation. These results have brought to light a number of issues requiring additional study. In the present study, two numerical codes are used for a wide range of Mach numbers, Reynolds numbers, grid sizes, and numbers of grid points to confirm the existence of the saddle point of attachment in the flow before an obstacle. The computational results near the critical point are theoretically analyzed. The impact and significance of the saddle point of attachment to the interpretation of experimental surface flow patterns and the definitions of lines of separation and attachment are discussed. A line of oil accumulating from both sides can be either a line of separation or a line of attachment, depending on the characteristics of the saddle point. C1 DAVID TAYLOR RES CTR,BETHESDA,MD 20084. ROCKWELL INT CORP,CTR SCI,THOUSAND OAKS,CA 91360. RP HUNG, CM (reprint author), NASA,MOFFETT FIELD,CA 94035, USA. NR 20 TC 15 Z9 16 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1992 VL 30 IS 6 BP 1561 EP 1569 DI 10.2514/3.11101 PG 9 WC Engineering, Aerospace SC Engineering GA HX732 UT WOS:A1992HX73200016 ER PT J AU MELCHIOR, FM SRINIVASAN, RS CHARLES, JB AF MELCHIOR, FM SRINIVASAN, RS CHARLES, JB TI MATHEMATICAL-MODELING OF HUMAN CARDIOVASCULAR-SYSTEM FOR SIMULATION OF ORTHOSTATIC RESPONSE SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Review DE MATHEMATICAL MODELS; COMPUTER SIMULATION; SHORT-TERM RESPONSE; ORTHOSTATIC STRESSES ID PRESSURE-VOLUME RELATIONSHIPS; HUMAN ARTERIAL SYSTEM; CANINE LEFT-VENTRICLE; BLOOD-FLOW; INSTANTANEOUS PRESSURE; VASCULAR-RESISTANCE; ELASTIC PROPERTIES; CARDIAC-OUTPUT; CIRCULATION; CARDIOPULMONARY AB This paper deals with the short-term response of the human cardiovascular system to orthostatic stresses in the context of developing a mathematical model of the overall system. It discusses the physiological issues involved and how these issues have been handled in published cardiovascular models for simulation of orthostatic response. Most of the models are stimulus specific with no demonstrated capability for simulating the responses to orthostatic stimuli of different types. A comprehensive model incorporating all known phenomena related to cardiovascular regulation would greatly help to interpret the various orthostatic responses of the system in a consistent manner and to understand the interactions among its elements. This paper provides a framework for future efforts in mathematical modeling of the entire cardiovascular system. C1 KRUG LIFE SCI, 1290 HERCULES DR, SUITE 120, HOUSTON, TX 77058 USA. CTR ESSAIS VOL, MED AEROSP LAB, F-91228 BRETIGNY SUR ORGE, FRANCE. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. NR 105 TC 36 Z9 37 U1 3 U2 9 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD JUN PY 1992 VL 262 IS 6 BP H1920 EP H1933 PN 2 PG 14 WC Physiology SC Physiology GA JC377 UT WOS:A1992JC37700041 PM 1621848 ER PT J AU KLINGLER, JM STOWE, RP OBENHUBER, DC GROVES, TO MISHRA, SK PIERSON, DL AF KLINGLER, JM STOWE, RP OBENHUBER, DC GROVES, TO MISHRA, SK PIERSON, DL TI EVALUATION OF THE BIOLOG AUTOMATED MICROBIAL IDENTIFICATION SYSTEM SO APPLIED AND ENVIRONMENTAL MICROBIOLOGY LA English DT Note ID METHYLOBACTERIUM-MESOPHILICUM AUSTIN; PIGMENTED FACULTATIVE METHYLOTROPHS; COMB-NOV-CORRIG; RADIOTOLERANS ITO; WATER-TREATMENT; POTABLE WATER; HANSON 1976; BACTERIA; HYBRIDIZATION; EMENDATION AB Biolog's identification system was used to identify 39 American Type Culture Collection reference taxa and 45 gram-negative isolates from water samples. Of the reference strains, 98% were identified to genus level and 76% to species level within 4 to 24 h. Identification of some authentic strains of Enterobacter, Klebsiella, and Serratia was unreliable. A total of 93% of the water isolates were identified. C1 KRUG LIFE SCI INC,HOUSTON,TX 77058. RP KLINGLER, JM (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,1290 HERCULES DR,SUITE 120,HOUSTON,TX 77058, USA. NR 32 TC 85 Z9 89 U1 1 U2 6 PU AMER SOC MICROBIOLOGY PI WASHINGTON PA 1325 MASSACHUSETTS AVENUE, NW, WASHINGTON, DC 20005-4171 SN 0099-2240 J9 APPL ENVIRON MICROB JI Appl. Environ. Microbiol. PD JUN PY 1992 VL 58 IS 6 BP 2089 EP 2092 PG 4 WC Biotechnology & Applied Microbiology; Microbiology SC Biotechnology & Applied Microbiology; Microbiology GA HX945 UT WOS:A1992HX94500046 PM 11536500 ER PT J AU WHITEMAN, DN MELFI, SH FERRARE, RA AF WHITEMAN, DN MELFI, SH FERRARE, RA TI RAMAN LIDAR SYSTEM FOR THE MEASUREMENT OF WATER-VAPOR AND AEROSOLS IN THE EARTHS ATMOSPHERE SO APPLIED OPTICS LA English DT Article DE RAMAN; LIDAR; WATER VAPOR; AEROSOLS ID MARINE STRATOCUMULUS AB A nighttime operating Raman lidar system that is designed for the measurement of high vertical and temporal resolution profiles of the water vapor mixing ratio and the aerosol backscattering ratio is described. The theory of the measurements is presented. Particular attention is given to operational problems that have been solved during the development of the system. Data are presented from Sept. 1987 and described in their meteorological context. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHER LAB,GREENBELT,MD 20771. UNIV SPACE RES ASSOC,WASHINGTON,DC. RP WHITEMAN, DN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERRESTRIAL PHYS LAB,CODE 924,GREENBELT,MD 20771, USA. NR 24 TC 237 Z9 249 U1 3 U2 20 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUN 1 PY 1992 VL 31 IS 16 BP 3068 EP 3082 PG 15 WC Optics SC Optics GA HV954 UT WOS:A1992HV95400024 PM 20725252 ER PT J AU BURRIS, J MCGEE, TJ HEAPS, W AF BURRIS, J MCGEE, TJ HEAPS, W TI UV RAMAN CROSS-SECTIONS IN NITROGEN SO APPLIED SPECTROSCOPY LA English DT Note DE RAMAN SPECTROSCOPY C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 917,GREENBELT,MD 20771. RI McGee, Thomas/G-4951-2013 NR 3 TC 8 Z9 8 U1 0 U2 4 PU SOC APPLIED SPECTROSCOPY PI FREDERICK PA 201B BROADWAY ST, FREDERICK, MD 21701 SN 0003-7028 J9 APPL SPECTROSC JI Appl. Spectrosc. PD JUN PY 1992 VL 46 IS 6 BP 1076 EP 1076 DI 10.1366/0003702924124448 PG 1 WC Instruments & Instrumentation; Spectroscopy SC Instruments & Instrumentation; Spectroscopy GA HZ915 UT WOS:A1992HZ91500030 ER PT J AU NEFF, SG HUTCHINGS, JB AF NEFF, SG HUTCHINGS, JB TI EVOLUTION OF LUMINOUS IRAS SOURCES - RADIO IMAGING SO ASTRONOMICAL JOURNAL LA English DT Article ID SPIRAL GALAXIES; SEYFERT-GALAXIES; NUCLEAR REGION; QUASARS; EMISSION; MORPHOLOGY; MERGER; INNER AB We present and discuss observations of the compact radio morphology of 111 luminous IRAS-selected active galaxies covering a wide range of IR and optical properties. Of these sources, 72 are observed for the first time with the VLA 1 A configuration. The circumnuclear radio sources are generally small and weak, with 15 nondetections to a limit of approximately 0.4 mJy. Comparison with the IR and optical properties of the objects indicates that the radio sources tum on within 10(8) yr of the tidal encounter that is presumed to generate the IR activity. However, the radio sources do not all appear at the same time. The radio observations are consistent with the evolution scenario for luminous IRAS galaxies suggested by Hutchings & Neff [AJ, 101, 434(1991)]. C1 NATL RES COUNCIL CANADA,DOMIN ASTROPHYS OBSERV,VICTORIA V8X 4M6,BC,CANADA. RP NEFF, SG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 45 TC 50 Z9 50 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1992 VL 103 IS 6 BP 1746 EP 1760 DI 10.1086/116192 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV913 UT WOS:A1992HV91300004 ER PT J AU JACOBSON, RA CAMPBELL, JK TAYLOR, AH SYNNOTT, SP AF JACOBSON, RA CAMPBELL, JK TAYLOR, AH SYNNOTT, SP TI THE MASSES OF URANUS AND ITS MAJOR SATELLITES FROM VOYAGER TRACKING DATA AND EARTH-BASED URANIAN SATELLITE DATA SO ASTRONOMICAL JOURNAL LA English DT Article ID RADIO SCIENCE; GRAVITY-FIELD; RING ORBITS; SYSTEM; PIONEER AB Analysis of the Doppler-tracking data and star-satellite imaging from the Voyager 2 spacecraft combined with Earth-based astrometric satellite observations has yielded improved values for the masses of the Uranian system and the satellites Ariel, Umbriel, Titania, Oberon, and Miranda. The present results are consistent with those previously published-Tyler et al. [Science, 233, 79 (1986)], Anderson et al. [J. Geophys. Res., 92, 14877 (1987)], Laskar & Jacobson [A&A, 188, 212 (1987)], Brown et al. [Uranus, p. 513 (1991)]. Masses are expressed as the product GM, the universal gravitational constant G times the mass M of the body, in units of (km3 s-2). The satellite masses are (4.4 +/- 0.5) for Miranda, (90.3 +/- 8.0) for Ariel, (78.2 +/- 9.0) for Umbriel, (235.3 +/- 6.0) for Titania, and (201.1 +/- 5.0) for Oberon. The mass of the Uranian system is (5 794 548.6 +/- 7.0) and the ratio of the mass of the Sun to the mass of the Uranian system is (22 902.982 +/- 0.028). Quoted errors are standard errors and are our assessment of the true rather than the formal errors. The Uranus rotational pole orientation angles and gravity harmonic coefficients were fixed at the values determined by French et al. [Icarus, 73, 349 (1988)] from stellar occultations of the Uranian rings observed from both the Earth and Voyager 2 and from the occultation of the spacecraft radio signal. RP JACOBSON, RA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 30 TC 39 Z9 41 U1 0 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1992 VL 103 IS 6 BP 2068 EP 2078 DI 10.1086/116211 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV913 UT WOS:A1992HV91300023 ER PT J AU RUSSELL, JL JAUNCEY, DL HARVEY, BR WHITE, GL REYNOLDS, JE MA, C JOHNSTON, KJ NOTHNAGEL, A NICOLSON, G KINGHAM, K HINDSLEY, R DEVEGT, C ZACHARIAS, N MALIN, DF AF RUSSELL, JL JAUNCEY, DL HARVEY, BR WHITE, GL REYNOLDS, JE MA, C JOHNSTON, KJ NOTHNAGEL, A NICOLSON, G KINGHAM, K HINDSLEY, R DEVEGT, C ZACHARIAS, N MALIN, DF TI A RADIO OPTICAL REFERENCE FRAME .3. ADDITIONAL RADIO AND OPTICAL POSITIONS IN THE SOUTHERN-HEMISPHERE SO ASTRONOMICAL JOURNAL LA English DT Article ID VLBI; INTERFEROMETRY; CATALOG AB Radio and optical positions are presented for southern hemisphere extragalactic sources from the Parkes 2.7 GHz survey. Sixty-one sources were observed with Mark III VLBI at 8.4 GHz (X band) between Tidbinbilla, Australia and Hartebeesthoek, South Africa. The results presented are part of the effort to establish a global reference frame of 400 extragalactic radio sources. Radio positions with approximately 10 milliarcsec errors have been estimated for 39 sources not previously in our radio reference frame catalog, and provisional positions were obtained for two additional sources, bringing the total number of catalog sources to 276. The principal source of error is the uncalibrated ionosphere. Of the remaining sources five were completely undetected, six were either too faint or too resolved, and nine had previous catalog positions. Optical positions on the FK5 system have also been measured for four southern sources using prime focus plates from the Anglo-Australian 4 m telescope with an accuracy 0.06". This raises to 40 the number of radio sources with accurately measured positions for their optical counterparts. C1 APPL RES CORP,LANDOVER,MD 20785. CSIRO,AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,CANBERRA,ACT 2601,AUSTRALIA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV BONN,INST GEODET,W-5300 BONN,GERMANY. HARTEBEESTHOEK RADIO ASTRON OBSERV,KRUGERSDORP,SOUTH AFRICA. USN OBSERV,WASHINGTON,DC 20390. USNO,BLACK BIRCH ASTROMET OBSERV,BLENHEIM,NEW ZEALAND. UNIV HAMBURG,HAMBURGER STERNWARTE,W-2000 HAMBURG 13,GERMANY. ANGLO AUSTRALIAN OBSERV,EPPING,NSW 2121,AUSTRALIA. RP RUSSELL, JL (reprint author), USN,RES LAB,CODE 4210,WASHINGTON,DC 20375, USA. RI Ma, Chopo/D-4751-2012 NR 17 TC 28 Z9 28 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1992 VL 103 IS 6 BP 2090 EP 2098 DI 10.1086/116213 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV913 UT WOS:A1992HV91300025 ER PT J AU PRUSTI, T CLARK, FO LAUREIJS, RJ WAKKER, BP WESSELIUS, PR AF PRUSTI, T CLARK, FO LAUREIJS, RJ WAKKER, BP WESSELIUS, PR TI AN IRAS STUDY OF PRE-MAIN SEQUENCE STARS IN B209 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, PRE-MAIN-SEQUENCE; INTERSTELLAR MEDIUM, CLOUDS, B209; INFRARED RADIATION ID T-TAURI STARS; MOLECULAR CLOUD; DENSE CORES; DARK CLOUD; MASS STARS; AURIGA; PHOTOMETRY; COMPLEX AB We have constructed high resolution IRAS maps of the B209 star forming region in the Taurus complex. By combining survey scans with pointed observations using advanced techniques specially developed to handle IRAS data in crowded fields, we have constructed images that reveal two new pre-main sequence (PMS) objects. One of these, IRAS 04114+2757G, has far infrared colours close to those of typical T Tauri stars and is probably associated with a faint stellar object visible on the POSS prints. The other new PMS source, IRAS 04111+2800G, is a deeply embedded object not detected at 12-mu-m and not optically visible. The object is projected close to the centre of an ammonia core. Our detection of compact blue and red shifted (CO)-C-12 emission peaks around the position of IRAS 04111+2800G confirms the PMS nature and youth of this object. We have examined the reasons causing the exclusion of IRAS 04111+2800G and IRAS 04114+2757G from the IRAS Point Source Catalog and estimated the incompleteness of the currently known sample of embedded PMS stars in Taurus. The implications for the determination of evolutionary time scales in low mass star formation are discussed. C1 KAPTEYN ASTRON INST, 9700 AV GRONINGEN, NETHERLANDS. PHILLIPS LAB, GEOPHYS DIRECTORATE, BACKGROUNDS BRANCH, BEDFORD, MA 01731 USA. JET PROP LAB, CTR INFRARED PROC & ANAL, PASADENA, CA 91109 USA. UNIV ILLINOIS, DEPT ASTRON, URBANA, IL 61801 USA. LAB SPACE RES, 9700 AV GRONINGEN, NETHERLANDS. NR 35 TC 12 Z9 12 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 JUN PY 1992 VL 259 IS 2 BP 537 EP 542 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JB318 UT WOS:A1992JB31800027 ER PT J AU QUIRRENBACH, A MOZURKEWICH, D ARMSTRONG, JT JOHNSTON, KJ COLAVITA, MM SHAO, M AF QUIRRENBACH, A MOZURKEWICH, D ARMSTRONG, JT JOHNSTON, KJ COLAVITA, MM SHAO, M TI INTERFEROMETRIC OBSERVATIONS OF MIRA (O-CETI) SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE INTERFEROMETRY; STARS, ATMOSPHERES OF; STARS, DIAMETERS OF; STARS, LONG-PERIOD VARIABLES; STARS, VARIABLE AB The long-period variable Mira (omicron-Ceti) has been observed at 800 nm wavelength with the MkIII Optical Interferometer at photometric phases phi = 0.96, 0.05, and 0.14 in 1990; some additional data were taken in 1989. The star is not spherically symmetric, and temporal variations of the size and the position angle of the asymmetry are detected. The visibility data can be represented by two uniform elliptical disks, which could correspond to different layers in Mira's atmosphere. If the size variations are interpreted in terms of physical motion of the emitting material, an infall velocity of approximately 15 km s-1 around phi = 0 is derived. C1 USN, RES LAB, CTR ADV SPACE SENSING, WASHINGTON, DC 20375 USA. JET PROP LAB, PASADENA, CA 91109 USA. UNIV SPACE RES ASSOC, WASHINGTON, DC USA. RP QUIRRENBACH, A (reprint author), USN OBSERV, NRL USNO OPT INTERFEROMETER PROJECT, AD5, 34TH ST & MASS AVE NW, WASHINGTON, DC 20392 USA. NR 12 TC 46 Z9 46 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUN PY 1992 VL 259 IS 1 BP L19 EP L22 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX468 UT WOS:A1992HX46800006 ER PT J AU BENNETT, CL SMOOT, GF JANSSEN, M GULKIS, S KOGUT, A HINSHAW, G BACKUS, C HAUSER, MG MATHER, JC ROKKE, L TENORIO, L WEISS, R WILKINSON, DT WRIGHT, EL DEAMICI, G BOGGESS, NW CHENG, ES JACKSON, PD KEEGSTRA, P KELSALL, T KUMMERER, R LINEWEAVER, C MOSELEY, SH MURDOCK, TL SANTANA, J SHAFER, RA SILVERBERG, RF AF BENNETT, CL SMOOT, GF JANSSEN, M GULKIS, S KOGUT, A HINSHAW, G BACKUS, C HAUSER, MG MATHER, JC ROKKE, L TENORIO, L WEISS, R WILKINSON, DT WRIGHT, EL DEAMICI, G BOGGESS, NW CHENG, ES JACKSON, PD KEEGSTRA, P KELSALL, T KUMMERER, R LINEWEAVER, C MOSELEY, SH MURDOCK, TL SANTANA, J SHAFER, RA SILVERBERG, RF TI COBE DIFFERENTIAL MICROWAVE RADIOMETERS - CALIBRATION TECHNIQUES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; INSTRUMENTATION, DETECTORS ID COSMIC-BACKGROUND-EXPLORER AB The COBE spacecraft was launched 1989 November 18 UT carrying three scientific instruments into Earth orbit for studies of cosmology. One of these instruments, the Differential Microwave Radiometer (DMR), is designed to measure the large-angular-scale temperature anisotropy of the cosmic microwave background radiation at three frequencies (31.5, 53, and 90 GHz). In this paper we present three methods used to calibrate the DMR. First, the signal difference between beam-filling hot and cold targets observed on the ground provides a primary calibration that is transferred to space by noise sources internal to the instrument. Second, the Moon is used in flight as an external calibration source. Third, the signal arising from the Doppler effect due to the Earth's motion around the barycenter of the solar system is used as an external calibration source. Preliminary analysis of the external source calibration techniques confirms the accuracy of the currently more precise ground-based calibration. Assuming the noise source behavior did not change from the ground-based calibration to flight we derive a 0.1%-0.4% relative and 0.7%-2.5% absolute calibration uncertainty, depending on radiometer channel. C1 LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. HUGHES STX CORP,LANHAM,MD 20706. GEN RES CORP,DANVERS,MA 01923. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. JET PROP LAB,PASADENA,CA 91109. MIT,DEPT PHYS,CAMBRIDGE,MA 02139. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. RP BENNETT, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 685,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012; Kogut, Alan/D-6293-2012; Rokke, Laurie/I-5642-2015 OI Rokke, Laurie/0000-0002-5696-7240 NR 14 TC 41 Z9 41 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP 466 EP 482 DI 10.1086/171363 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV512 UT WOS:A1992HV51200007 ER PT J AU LONSDALE, CJ LONSDALE, CJ SMITH, HE AF LONSDALE, CJ LONSDALE, CJ SMITH, HE TI A VLBI SEARCH FOR AGN RADIO CORES IN STARBURST GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; GALAXIES, STELLAR CONTENT; RADIO CONTINUUM, GALAXIES; TECHNIQUES, INTERFEROMETRIC ID ACTIVE GALACTIC NUCLEI; FAR-INFRARED GALAXIES; LONG BASELINE INTERFEROMETRY; SEYFERT-GALAXIES; SPIRAL GALAXIES; IRAS OBSERVATIONS; VLA OBSERVATIONS; CONTINUUM OBSERVATIONS; INTERACTING GALAXIES; LUMINOSITY FUNCTION AB We have searched for compact, high brightness temperature, milliarcsecond synchrotron cores in four star-burst galaxies which have compact VLA radio sources and high far-infrared luminosities but no optical spectroscopic evidence for a classical active nucleus. The search, using a sensitive Mk III VLBI array at lambda = 18 cm, has resulted in the detection of compact radio sources in two of the four galaxies: Mrk 297 (NGC 6052) and Mrk 171 (NGC 3690/IC 694). In Mrk 297 the source lies in an obscure clump near the edge of the galaxy. This is either the first known case of a detached nucleus (presumably as a result of disruption during a merger) or a radio supernova of unprecedented luminosity. No VLBI-scale emission was detected in the nucleus of the starburst galaxy Mrk 201 (NGC 4194), or in Mrk 928a, although the Seyfert 2 nucleus Mrk 928b was detected. We have also observed two other galaxies with compact VLA radio sources: the Seyfert 2 nucleus Mrk 620 and the previously unclassified galaxy Mrk 520. Mrk 620 was found to have a milliarcsecond core, but Mrk 520 was not detected. We have obtained optical spectroscopy for five of these galaxies, including Mrk 520, which is shown to be a Seyfert 1.9 galaxy. One VLBI detection rate of starburst galaxies with compact VLA radio cores is therefore 50% (2/4), and of Seyfert 2 galaxies 66% (2/3). If the VLBI sources in Mrk 297 and Mrk 171 are indeed of active galactic nucleus origin, these results demonstrate that, in luminous starburst galaxies, an active nucleus can effectively be completely hidden from view in the optical by dust. They also support a physical or causal connection between classical nuclear activity and the starburst phenomenon. Luminous radio supernovae, associated with the massive starbursts in Mrk 297 and Mrk 171, remain a plausible alternative interpretation. C1 CALTECH, CTR INFRARED PROC & ANAL, PASADENA, CA 91125 USA. JET PROP LAB, PASADENA, CA 91109 USA. CALTECH, DIV PHYS MATH & ASTRON, PASADENA, CA 91125 USA. RP MIT, HAYSTACK OBSERV, WESTFORD, MA 01886 USA. NR 81 TC 41 Z9 41 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP 629 EP 650 DI 10.1086/171377 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV512 UT WOS:A1992HV51200021 ER PT J AU BAILES, M KNIFFEN, DA AF BAILES, M KNIFFEN, DA TI GALACTIC GAMMA-RAY EMISSION FROM RADIO PULSARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY; STELLAR CONTENT; GAMMA-RAYS; OBSERVATIONS; PULSARS; GENERAL ID RAPIDLY SPINNING PULSARS; ENERGETIC RADIATION; PERIOD AB Using both the polar cap and outer gap models of pulsar gamma-ray emission, the pulsars' contribution to the Galactic gamma-ray emission is derived. A Monte Carlo technique is used to model the Galactic pulsar population, and their contribution to the Galactic gamma-ray emission is found to depend strongly upon their birth properties, which remain controversial. The "standard model" of radio pulsar evolution suggests that the majority of the observed gamma-ray emission originates from radio pulsars. However, other models of the Galactic pulsar population, which have pulsars being born with periods near 0s.5, suggest that the contribution is much smaller. For any model, the majority of this emission arises from pulsars currently unknown as radio pulsars. This result holds for both the polar cap, and outer gap models, and suggests that the pulsar contribution to the Galactic gamma-ray emission might be much higher than previous calculations have suggested. The result can be inverted to place limits upon the Galactic distribution of radio pulsars and their birth properties. If pulsars are the predominant source of Galactic gamma-rays, then their mean initial field strengths and periods must be less-than-or-similar-to 10(12) G and less-than-or-similar-to 20 ms, respectively. Although the number of known pulsars detectable by the Compton Gamma Ray Observatory (Compton) is only expected to be less-than-or-similar-to 10, there may be many more observable as point sources either undetectable as radio pulsars due to beaming effects, or simply below the detection threshold of previous radio pulsar surveys. Deep radio observations of all Compton point sources is therefore recommended. It is found that the millisecond pulsars may also contribute significantly to Galactic gamma-ray emission, although population estimates, and the validity of gamma-ray emission models at millisecond pulsar periods and field strengths require confirmation. C1 UNIV SPACE RES CORP,COLUMBIA,MD. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 37 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP 659 EP 666 DI 10.1086/171379 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV512 UT WOS:A1992HV51200023 ER PT J AU TAMURA, M YAMASHITA, T AF TAMURA, M YAMASHITA, T TI INFRARED MORPHOLOGY OF MASS OUTFLOW FROM GL-2591 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (GL-2591); ISM, JETS AND OUTFLOWS; ISM, MOLECULES; SHOCK WAVES ID MOLECULAR-HYDROGEN EMISSION; YOUNG STELLAR OBJECTS; REFLECTION NEBULA; STAR-FORMATION; BIPOLAR FLOW; AFGL 2591; AFGL-2591; CLOUDS; ORION; POLARIZATION AB Near-infrared long-slit spectrophotometry of GL 2591 has been conducted in order to seek for possible diagnostic tracers of mass outflows and to reveal the morphology of mass outflow from a young stellar object. Extensive molecular hydrogen and relatively compact Br-gamma emission have been discovered and mapped in this source for the first time. The upsilon = 1-0 S(1) H-2 emission reveals a bipolar structure centered on the strong IR continuum source, GL 2591 IRS, extending over 90" (0.9 pc) in the east-west direction and composed of several knots. To the west of the IR source, these knots are interconnected by weaker H-2 emission, while to the east, there is only a strong isolated peak. The line ratios of molecular hydrogen show a systematic change among these knots; the outermost two knots at the terminals of the bipolar H-2 lobes are generally consistent with shock excitation, while the two knots nearer to the central infrared source have a higher vibration temperature, indicative of a significant contribution of fluorescent excitation. The Br-gamma emission delineates a monopolar jetlike structure emanating 20" from the IR source to the southwest. The morphology and flux of the Br-gamma can be explained by a fast shock model. The 2-mu-m continuum shows a conical structure with its apex centered at the IR source, as has been indicated by previous broad-band imaging. The extension of H-2 and Br-gamma is consistent with this monopolar 2-mu-m nebula, suggesting the presence of an inclined, obscuring disk whose plane is roughly perpendicular to the extended IR emission. We interpret the H-2, Br-gamma, and 2-mu-m continuum as the distributions of shocked molecular gas, ionized gas, and dust grains associated with a bipolar outflow from GL 2591 IRS, and discuss the interrelationship of these phenomena. C1 NATL ASTRON OBSERV,MITAKA KU,TOKYO 181,JAPAN. ASSOC UNIV RES ASTRON INC,NATL OPT ASTRON OBSERV,TUCSON,AZ. RP TAMURA, M (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 62 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP 710 EP 718 DI 10.1086/171382 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV512 UT WOS:A1992HV51200026 ER PT J AU CLEMENS, JC NATHER, RE WINGET, DE ROBINSON, EL WOOD, MA CLAVER, CF PROVENCAL, J KLEINMAN, SJ BRADLEY, PA FRUEH, ML GRAUER, AD HINE, BP FONTAINE, G ACHILLEOS, N WICKRAMASINGHE, DT MARAR, TMK SEETHA, S ASHOKA, BN ODONOGHUE, D WARNER, B KURTZ, DW MARTINEZ, P VAUCLAIR, G CHEVRETON, M BARSTOW, MA KANAAN, A KEPLER, SO AUGUSTEIJN, T VANPARADIJS, J HANSEN, CJ AF CLEMENS, JC NATHER, RE WINGET, DE ROBINSON, EL WOOD, MA CLAVER, CF PROVENCAL, J KLEINMAN, SJ BRADLEY, PA FRUEH, ML GRAUER, AD HINE, BP FONTAINE, G ACHILLEOS, N WICKRAMASINGHE, DT MARAR, TMK SEETHA, S ASHOKA, BN ODONOGHUE, D WARNER, B KURTZ, DW MARTINEZ, P VAUCLAIR, G CHEVRETON, M BARSTOW, MA KANAAN, A KEPLER, SO AUGUSTEIJN, T VANPARADIJS, J HANSEN, CJ TI WHOLE EARTH TELESCOPE OBSERVATIONS OF V471 TAURI - THE NATURE OF THE WHITE-DWARF VARIATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS; INDIVIDUAL (V471 TAURI); STARS, OSCILLATIONS; WHITE DWARFS ID X-RAY; PULSATION; STARS AB We have conducted time-series photometric observations of the binary star V471 Tauri using the Whole Earth Telescope observing network. Our purpose was to determine the mechanism responsible for causing the 555 and 277 s periodic luminosity variations exhibited by the white dwarf in this binary. Previous observers have proposed that either g-mode pulsations or rotation of an accreting magnetic white dwarf could cause the variations, but were unable to decide which was the correct model. Our observations have answered this question. Learning the cause of the white dwarf variations has been possible because of our discovery of a periodic signal at 562 s in the Johnson U-band flux of the binary. By identifying this signal as reprocessed radiation and using its phase to infer the phase of the shorter wavelength radiation which produces it, we have been able to compare the phase of the 555 s U-band variations to the phase of the X-ray variations. We have found that U-band maximum coincides with X-ray minimum. From this result we have concluded that the magnetic rotator model accurately describes the variations we observe, but that models involving g-mode pulsations do not. C1 INDIAN SPACE RES ORG,SATELLITE CTR,DIV TECH PHYS,BANGALORE 560017,INDIA. OBSERV MIDI PYRENEES,F-31400 TOULOUSE,FRANCE. OBSERV PARIS,F-92195 MEUDON,FRANCE. UNIV FED RIO GRANDE SUL,INST FIS,BR-91500 PORTO ALEGRE,RS,BRAZIL. EUROPEAN SO OBSERV,LA SILLA,CHILE. UNIV AMSTERDAM,FAC WISKUNDE,1018 WB AMSTERDAM,NETHERLANDS. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. UNIV LEICESTER,DEPT PHYS & ASTRON,LEICESTER LE1 7RH,ENGLAND. AUSTRALIAN NATL UNIV,DEPT MATH,CANBERRA,ACT 2600,AUSTRALIA. UNIV MONTREAL,DEPT PHYS,MONTREAL H3C 3J7,QUEBEC,CANADA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV HAWAII,INST ASTRON,MAUNA KEA OBSERV,HONOLULU,HI 96822. UNIV ARKANSAS,DEPT PHYS & ASTRON,LITTLE ROCK,AR 72204. UNIV HAWAII,CNRS,NATL RES COUNCIL CANADA,CANADA FRANCE HAWAII TELESCOPE,HONOLULU,HI 96822. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. UNIV CAPE TOWN,DEPT ASTRON,RONDEBOSCH 7700,SOUTH AFRICA. RP CLEMENS, JC (reprint author), UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712, USA. RI Achilleos, Nicholas/C-1647-2008; Kepler, S. O. /H-5901-2012; OI Kepler, S. O. /0000-0002-7470-5703; Achilleos, Nicholas/0000-0002-5886-3509 NR 16 TC 33 Z9 33 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP 773 EP 783 DI 10.1086/171387 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV512 UT WOS:A1992HV51200031 ER PT J AU NATTA, A PALLA, F BUTNER, HM EVANS, NJ HARVEY, PM AF NATTA, A PALLA, F BUTNER, HM EVANS, NJ HARVEY, PM TI INFRARED STUDIES OF PRE-MAIN-SEQUENCE INTERMEDIATE-MASS STARS - LKH-ALPHA-198 SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; INFRARED, STARS; STARS, INDIVIDUAL (LKH-ALPHA-198); STARS, PRE-MAIN-SEQUENCE ID T-TAURI STARS; YOUNG STELLAR OBJECTS; LKH-ALPHA 198; MOLECULAR CLOUDS; INTERSTELLAR MATTER; IRAS OBSERVATIONS; HERBIG AE; DUST; EMISSION; SPECTRA AB Far-infrared scans of LkH-alpha 198 at 50 and 100-mu-m along several directions reveal an extended, roughly spherical source with an average FWHM of 33" or 2 x 10(4) AU at 100-mu-m and up to 18" or 1.5 x 10(4) AU at 50-mu-m. By comparing the observed properties at optical, infrared, and millimeter wavelengths with the predictions of radiation transfer models, we estimate a luminosity of 250 L. at a distance of 600 pc. The optical depth at 100-mu-m is 0.004-0.006, implying a mass of approximately 2 M. within a radius of 10(4) AU. The dust configuration is characterized by a power-law distribution n(r) approximately r-alpha, with alpha-approximately 0.5, in most of the directions around the star and over large distances. The inner radius of the dusty envelope is probably rather small, r(i) less-than-or-similar-to 300 AU (0".5), and it may be as small as the dust destruction front: in LkH-alpha 198 there is no evidence of a large region devoid of grains. The fit to the observed spectral energy distribution (SED) from optical to millimeter wavelengths favors a model that includes a disk and a spherical envelope. The former is required in order to provide a good match to the SED at near-infrared wavelengths. The disk mass is 0.27 M., i.e., approximately 7% of the stellar mass. Alternatively, the SED can be fitted by a spherical dust envelope only, if there is a component of very small grains and polycyclic aromatic hydrocarbons. Within the current scenario of star formation, mostly developed for solar-mass stars, it is not easy to account for the flat density profile of the dusty envelope we observe around LkH-alpha 198. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV TEXAS,AUSTIN,TX 78712. RP NATTA, A (reprint author), OSSERV ASTROFIS ARCETRI,LARGO E FERMI 5,I-50125 FLORENCE,ITALY. OI palla, francesco/0000-0002-3321-0456 NR 74 TC 40 Z9 40 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP 805 EP 816 DI 10.1086/171389 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV512 UT WOS:A1992HV51200033 ER PT J AU BENKA, SG HOLMAN, GD AF BENKA, SG HOLMAN, GD TI A THERMAL NONTHERMAL MODEL FOR SOLAR MICROWAVE-BURSTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE RADIATION MECHANISMS; CYCLOTRON AND SYNCHROTRON; SUN, FLARES; SUN, RADIO RADIATION ID TO-LIMB VARIATION; RUNAWAY ELECTRONS; X-RAY; RADIATION; FLARES; ACCELERATION; EMISSION; CORONA; PLASMA; SIGNATURES AB High-resolution spectra of microwave bursts from Owens Valley Radio Observatory show numerous departures from expectations based on simple thermal or nonthermal models. In particular, (1) approximately 80% of the events show more than one spectral peak; (2) many burst have a low-side spectral index steeper than the maximum expected slope; and (3) the peak frequency stays relatively constant, and changes intensity in concert with the secondary peaks throughout a given event's evolution. We develop a theoretical formalism allowing both thermal and nonthermal particles to coexist in the flaring plasma. Within this formalism, we show that the observed spectral features can be accounted for through gyrosynchrotron radiation. Specifically: 1. The "secondary" components seen on the low-frequency side of many spectra are nonthermal enhancements superposed upon thermal radiation, occurring between the thermal harmonics. 2. A steep optically thick slope is accounted for by the thermal absorption of nonthermal radiation. 3. If the coexistence of thermal and nonthermal particles is interpreted in terms of electron heating and acceleration in current sheets, a changing electric field strength can account for the gross evolution of the microwave spectra. We present our model distribution function, use it to calculate gyrosynchrotron spectra, and systematically analyze these spectra. We demonstrate the applicability of this approach by fitting an observed Owens Valley spectrum. Last, we offer our physical interpretation of the thermal/nonthermal distribution function as it relates to solar flares. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP BENKA, SG (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,CODE 4171B,WASHINGTON,DC 20375, USA. RI Holman, Gordon/C-9548-2012 NR 37 TC 47 Z9 48 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP 854 EP 864 DI 10.1086/171394 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV512 UT WOS:A1992HV51200038 ER PT J AU ZARRO, DM DENNIS, BR SLATER, GL AF ZARRO, DM DENNIS, BR SLATER, GL TI IMPULSIVE PHASE FE K-ALPHA EMISSION IN A FLARE OF 1989 MARCH SO ASTROPHYSICAL JOURNAL LA English DT Article DE RADIATION MECHANISMS; THERMAL; SUN, FLARES; SUN, X-RAYS, GAMMA-RAYS ID SOLAR MAXIMUM MISSION; X-RAY BURST; PHOTOSPHERIC IRON; SMM OBSERVATIONS; FLUORESCENCE; SPECTROMETER; SATELLITE; SPECTRA AB Observations of the Fe K-alpha soft X-ray line made with the Solar Maximum Mission bent crystal spectrometer on 0557 UT 1989 March 7 show evidence for enhanced Fe K-alpha line emission that is coincident (to within 15 s) with an intense hard X-ray (> 50 keV) burst. We investigate three different models for explaining the K-alpha enhancement: (i) photoexcitation by soft X-ray thermal bremsstrahlung radiation from an isothermal source; (ii) collisional excitation by nonthermal thick-target electrons; (iii) photoexcitation by a nonthermal hard X-ray flux distribution which extends with a power-law spectrum down to the Fe K-alpha ionization threshold at 7.1 keV. We find that, to within the limits of isothermal temperature and emission measure set by soft X-ray observations, the thermal photoexcitation model cannot reproduce satisfactorily the intensity of enhanced K-alpha emission during the hard X-ray impulsive phase. In particular, the impulsive phase K-alpha flux exceeds that predicted by the thermal photoexcitation model by approximately 3-sigma. On the other hand, we find that the electron-collisional model and the nonthermal power-law model are both equally capable of explaining the excess K-alpha flux (above that produced by thermal photoexcitation). We discuss the implications of our results for the nonthermal interpretation of impulsive hard X-ray bursts in solar flares. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94304 USA. RP APPL RES CORP, LANDOVER, MD 20785 USA. RI Dennis, Brian/C-9511-2012 NR 25 TC 14 Z9 14 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP 865 EP 871 DI 10.1086/171395 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV512 UT WOS:A1992HV51200039 ER PT J AU KELLER, JW COPLAN, MA GORUGANTHU, R AF KELLER, JW COPLAN, MA GORUGANTHU, R TI ELECTRON-ENERGY LOSS SPECTRA OF POLYCYCLIC AROMATIC-HYDROCARBONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; MOLECULAR PROCESSES ID DIFFUSE INTERSTELLAR BANDS; EMISSION; PARTICLES AB Polycyclic aromatic hydrocarbons (PAHs) have been tentatively identified as the source of infrared emission bands seen in reflection nebulae and other astronomical objects. PAHs may also play a role in other astronomical phenomena, but concrete identification of these systems await further understanding of the properties of PAHs as a class of molecules. We report on a survey of the electron energy loss spectroscopy of gas phase PAH molecules consisting of up to seven rings where we have limited the study to the more thermodynamically stable pericondensed systems. The aim of this work is to obtain absorption profiles (proportional to the oscillator strengths) from the visible to the soft X-ray region near 30 eV. C1 UNIV MARYLAND,INST PHYS & TECHNOL,COLLEGE PK,MD 20742. RP KELLER, JW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. RI Keller, John/I-5097-2013 NR 36 TC 12 Z9 12 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP 872 EP 875 DI 10.1086/171396 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV512 UT WOS:A1992HV51200040 ER PT J AU BOUGHN, SP CHENG, ES COTTINGHAM, DA FIXSEN, DJ AF BOUGHN, SP CHENG, ES COTTINGHAM, DA FIXSEN, DJ TI LIMITS ON GAUSSIAN FLUCTUATIONS IN THE COSMIC MICROWAVE BACKGROUND AT 19.2-GHZ SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND ID RADIATION; ANISOTROPY; RADIOMETER; SCALES AB The northern hemisphere data from the 19.2 GHz full sky survey are analyzed to place limits on the magnitude of Gaussian fluctuations in the cosmic microwave background implied by a variety of correlation functions. Included among the models tested are the monochromatic and Gaussian-shaped families, and those with power-law spectra for -2 less-than-or-equal-to n less-than-or-equal-to 1. We place an upper bound on the quadrupole anisotropy of DELTA-T/T < 3.2 x 10(-5) rms, and an upper bound on scale-invariant (n = 1) fluctuations of a2 < 4.5 x 10(-5) (95% confidence level). There is significant contamination of these data from Galactic emission, and improvement of our modeling of the Galaxy could yield a significant reduction of these upper bounds. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. RP BOUGHN, SP (reprint author), HAVERFORD COLL,STRAWBRIDGE OBSERV,HAVERFORD,PA 19041, USA. NR 10 TC 29 Z9 29 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP L49 EP L52 DI 10.1086/186396 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV513 UT WOS:A1992HV51300001 ER PT J AU BRAUN, DC DUVALL, TL LABONTE, BJ JEFFERIES, SM HARVEY, JW POMERANTZ, MA AF BRAUN, DC DUVALL, TL LABONTE, BJ JEFFERIES, SM HARVEY, JW POMERANTZ, MA TI SCATTERING OF P-MODES BY A SUNSPOT SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, OSCILLATIONS; SUNSPOTS AB The acoustic scattering properties of a large sunspot are determined from a Fourier-Hankel decomposition of p-mode amplitudes as measured from a 68 hr subset of a larger set of observation made at the south pole in 1988. We show that significant improvement in the measurement of p-mode scattering amplitudes results from the increased temporal frequency resolution provided by this data. Scattering phase shifts are unambiguously determined for the first time, and the dependence of the p-mode phase shift and absorption with wavenumber and frequency is presented. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP BRAUN, DC (reprint author), UNIV HAWAII,INST ASTRON,2680 WOODLAWN DR,HONOLULU,HI 96822, USA. RI Duvall, Thomas/C-9998-2012 NR 11 TC 76 Z9 76 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP L113 EP L116 DI 10.1086/186410 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV513 UT WOS:A1992HV51300015 ER PT J AU SMITH, AM HILL, RS VRBA, FJ TIMOTHY, JG AF SMITH, AM HILL, RS VRBA, FJ TIMOTHY, JG TI FAR-ULTRAVIOLET MAMA DETECTOR IMAGERY AND EMISSION-LINE CCD IMAGERY OF NGC-6240 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INTERACTIONS; GALAXIES, PECULIAR; GALAXIES, PHOTOMETRY; STARS, FORMATION ID ROCKET ULTRAVIOLET; INTERACTING GALAXY; STAR FORMATION; REGIONS AB We have obtained an image of the luminous infrared galaxy NGC 6240 at 1480 angstrom using a multianode microchannel array (MAMA) detector with a rocket-borne telescope. At distances greater than 12" from the nucleus the measured ultraviolet luminosity implies intensive star formation activity equal to 2-3 times that of a spiral galaxy such as M83. Optical images in the H-beta and [O III] lambda-5007 emission lines reveal a region of high excitation east of the nucleus between the centers of disks 1 and 2 as described by Bland-Hawthorn et al. C1 HUGHES STX CORP,LANHAM,MD 20706. USN OBSERV,FLAGSTAFF STN,FLAGSTAFF,AZ 86002. STANFORD UNIV,CTR SPACE SCI,STANFORD,CA 94305. RP SMITH, AM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 681,GREENBELT,MD 20771, USA. NR 18 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP L81 EP L84 DI 10.1086/186403 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV513 UT WOS:A1992HV51300008 ER PT J AU STARRFIELD, S SHORE, SN SPARKS, WM SONNEBORN, G TRURAN, JW POLITANO, M AF STARRFIELD, S SHORE, SN SPARKS, WM SONNEBORN, G TRURAN, JW POLITANO, M TI A PREDICTION OF THE GAMMA-RAY FLUX FROM NOVA HERCULIS 1991 SO ASTROPHYSICAL JOURNAL LA English DT Article DE NOVAE, CATACLYSMIC VARIABLES; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES ID OUTBURST AB Hydrodynamic simulations of thermonuclear runaways in the accreted hydrogen-rich envelopes on 1.0 M., 1.25 M., and 1.35 M. white dwarfs predict Na-22 and Al-26 gamma-ray emission from ONeMg novae in outburst. We present and discuss the ultraviolet observations made with the International Ultraviolet Explorer satellite of Nova Her 1991, the most recent bright ONeMg nova. A distance of 3.4 kpc and reddening of E(B-V) = 0.6 to Nova Her 1991 are determined by comparing its UV and optical outburst behavior with those of the extragalactic ONeMg nova LMC 1990 No. 1. Her 1991 was also detected by ROSAT five days into its outburst and we argue that a small fraction of the X-rays may be the product of Comptonized 1.2 and 0.5 MeV emission from the decay of Na-22. If the mass of the ejected shell is indeed as high as has been estimated by Woodward et al., approximately 10(-4) M., then our results predict that Na-22 gamma-ray emission from the ejecta of Nova Her 1991 should still be detectable by GRO in the spring of 1992. The detection level is expected to be approximately 5-sigma in a 2 week observation. Such a detection would strongly guide and constrain the hydrodynamic and nucleosynthesis simulations of nova outbursts on massive white dwarfs. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GHRS SCI TEAM,GREENBELT,MD 20771. LOS ALAMOS NATL LAB,DIV APPL THEORET PHYS,LOS ALAMOS,NM 87545. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS GRP,GREENBELT,MD 20771. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. RP STARRFIELD, S (reprint author), ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287, USA. NR 23 TC 48 Z9 48 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1992 VL 391 IS 2 BP L71 EP L74 DI 10.1086/186401 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV513 UT WOS:A1992HV51300006 ER PT J AU OWEN, FN WHITE, RA BURNS, JO AF OWEN, FN WHITE, RA BURNS, JO TI A 20 CENTIMETER VLA SURVEY OF ABELL CLUSTERS OF GALAXIES .2. IMAGES AND OPTICAL IDENTIFICATIONS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE GALAXIES, ACTIVE; GALAXIES, CLUSTERING; GALAXIES, JETS; RADIO CONTINUUM, GALAXIES; SURVEYS ID RADIO GALAXY AB We present radio contour maps, models, and optical identifications for 130 radio galaxies in Abell clusters of galaxies. C1 NASA,GODDARD SPACE FLIGHT CTR,SPACE & EARTH SCI DIRECTORATE,GREENBELT,MD 20771. NEW MEXICO STATE UNIV,LAS CRUCES,NM 88003. RP OWEN, FN (reprint author), NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801, USA. NR 14 TC 51 Z9 51 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUN PY 1992 VL 80 IS 2 BP 501 EP & DI 10.1086/191674 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV354 UT WOS:A1992HV35400002 ER PT J AU LIU, AK VACHON, PW PENG, CY BHOGAL, AS AF LIU, AK VACHON, PW PENG, CY BHOGAL, AS TI WAVE ATTENUATION IN THE MARGINAL ICE-ZONE DURING LIMEX SO ATMOSPHERE-OCEAN LA English DT Article ID SYNTHETIC APERTURE RADAR; SAR IMAGERY; SWELL; EDGE AB During the Labrador Ice Margin Experiments, LIMEX '87 in March 1987 and LIMEX '89 in March and April 1989, the Canada Centre for Remote Sensing (CCRS) CV-580 aircraft collected synthetic aperture radar (SAR) image data over the marginal ice zone off the east coast of Newfoundland, Canada. One aspect of these experimental programs was the observation of ocean waves penetrating into the marginal ice zone (MIZ). Based upon directional wavenumber spectra derived from SAR image data, the wave attenuation rate is estimated using SAR image spectra and compared with predictions from a model developed by Liu and Mollo-Christensen (1988). The wave and ice conditions were considerably different in LIMEX '87 and LIMEX '89. However, the model-data comparisons are very good for all ice conditions observed. Both the model and the SAR-derived wave attenuation rates show a characteristic roll-over at high wavenumbers. A model for the eddy viscosity is proposed, using dimensional analysis, as a simple function of ice roughness and wave-induced velocity. Eddy viscosities derived from SAR and wave buoy data for the wave attenuation rate show a trend that is consistent with the proposed model. C1 NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD 20771. CANADA CTR REMOTE SENSING,OTTAWA K1A 0Y7,ON,CANADA. SCI SYST & APPLICAT INC,LANHAM,MD 20706. INTERA KENTING,NEPEAN K2E 1E2,ON,CANADA. NR 19 TC 15 Z9 15 U1 0 U2 1 PU CANADIAN METEOROLOGICAL OCEANOGRAPHIC SOC PI OTTAWA PA 150 LOUIS PASTEUR PVT., STE 112, MCDONALD BUILDING, OTTAWA ON K1N 6N5, CANADA SN 0705-5900 J9 ATMOS OCEAN JI Atmos.-Ocean PD JUN PY 1992 VL 30 IS 2 BP 192 EP 206 PG 15 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA MG396 UT WOS:A1992MG39600003 ER PT J AU POLESE, A SANDLER, H MONTGOMERY, LD AF POLESE, A SANDLER, H MONTGOMERY, LD TI HEMODYNAMIC-RESPONSES TO SEATED AND SUPINE LOWER-BODY NEGATIVE-PRESSURE - COMPARISON WITH +GZ ACCELERATION SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID BLOCKADE AB Hemodynamic changes between upright and supine lower body negative pressure (LBNP) to levels of -70 mm Hg were compared in 8 subjects (5 males, 3 females) and correlated with their findings during simulated Shuttle reentry acceleration with a slow onset rate of 0.002 G/s (1,020 s to peak +2 Gz) and during gradual onset exposures (0.03 G/s) to +3 Gz and +4 Gz. Six of the 8 subjects were able to tolerate 2 min at peak +2 G., 2-5 min at +3 Gx, and 1-2 min at +4 G.. Heart rate (HR) at any given level of upright LBNP regularly exceeded supine levels. HR change at -50 mm Hg in upright subjects (+47.7 bpm from 74.1 +/- 1.9 (M +/- S.E.) bpm, control) was 2.6 times greater than in supine subjects (+18.3 bpm from 64.8 +/- 2.8 bpm, control). HR values at -40 mm Hg supine (73.7 +/- 2.6) matched seated upright pre-LBNP control levels (74.1 +/- 1.9 bpm), while values at -70 mm Hg supine (102.5 +/- 4.4 bpm) were not significantly different from those at - 40 mm Hg upright (103. 1 +/- 4.0 bpm). Peak HR during +3 Gz (145.8 +/- 7.7 bpm) and +4 Gz (1 52.3 +/- 6.5 bpm) significantly exceeded recorded supine and upright LBNP levels, whereas values at +2 G. (104.8 +/- 5.5 bpm) closely matched those at -40 mm Hg upright (103.1 +/- 4.0 bpm) and -70 mm Hg supine (102.5 +/- 4.4 bpm). Supine LBNP HR changes in this relatively small group of subjects closely matched those previously reported in the literature. Overall LBNP HR changes could be closely related by second-order polynomial equations. Diastolic (DBP) and mean arterial (MAP) blood pressures showed a nonsignificant tendency to decline during progressive LBNP exposure, while acceleration induced significant elevations. However, MAP (90.6 +/- 2.6 mm Hg) and DBP (75.8 +/- 2.0 mm Hg) at -40 mm Hg upright were similar to those at peak +2 Gz (93.2 +/- 4.5 mm Hg and 80.7 +/- 5.5 mm Hg, respectively). The magnitude of seated LBNP-induced leg pooling, measured by impedance plethysmography, was 65% of that found with +3 Gz (3.6 +/- 0.2 % DELTA-DVE) and +4 G. (3.6 +/- 0.1 % DELTA-DVE) and 64% of that with +2 Gz (3.7 +/- 0.3 % DELTA-DVE). Pooling during seated LBNP (-70 mm Hg, 2.38 +/- 0.4 % DELTA-DVE) was a significant 22% greater than supine LBNP (1.85 +/- 0.1 % DELTA-DVE). Results provide evidence that seated LBNP at a level of -40 mm Hg can serve as a static simulator for heart rate and mean blood pressure changes induced by the gradual onset acceleration stress occurring during Shuttle reentry. Findings also provide a rationale for use of LBNP during weightlessness as a means of imposing G-loading on the circulation prior to reentry. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 37 TC 13 Z9 17 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD JUN PY 1992 VL 63 IS 6 BP 467 EP 475 PG 9 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA HX203 UT WOS:A1992HX20300001 PM 1520215 ER PT J AU CAMPBELL, MR BILLICA, RD AF CAMPBELL, MR BILLICA, RD TI A REVIEW OF MICROGRAVITY SURGICAL INVESTIGATIONS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Review ID CHAMBER AB The likelihood of performing a surgical procedure in space will increase as the Soviet Mir space station is expanded and the Space Station Freedom becomes operational. A review of previous research and hardware development, performed mostly in parabolic flight both in the Soviet Union and the U.S., reveals an interest in surgical chambers to prevent cabin atmosphere contamination. Surgical techniques appear to be no more difficult than in a 1-G environment if a restraint system is used. Minimizing the chances of wound infection from the high particle count spacecraft atmosphere is an additional concern. Additional research is necessary to delineate the clinical significance of these problems and to further develop surgical techniques in microgravity. C1 NASA,LYNDON B JOHNSON SPACE CTR,MED OPERAT,HOUSTON,TX 77058. RP CAMPBELL, MR (reprint author), CLIFTON MED SURG CLIN ASSOC,201 S AVE T,CLIFTON,TX 76634, USA. NR 28 TC 29 Z9 29 U1 0 U2 0 PU AEROSPACE MEDICAL ASSOC PI ALEXANDRIA PA 320 S HENRY ST, ALEXANDRIA, VA 22314-3579 SN 0095-6562 J9 AVIAT SPACE ENVIR MD JI Aviat. Space Environ. Med. PD JUN PY 1992 VL 63 IS 6 BP 524 EP 528 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA HX203 UT WOS:A1992HX20300010 PM 1520223 ER PT J AU BLACKWELL, AL AF BLACKWELL, AL TI SIMULATION SOLUTION SO BIOSCIENCE LA English DT Letter RP BLACKWELL, AL (reprint author), NASA,AMES RES CTR,DIV SPACE PROJECTS,SYST DEV BRANCH,MOFFETT FIELD,CA 94035, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST BIOLOGICAL SCI PI WASHINGTON PA 1444 EYE ST, NW, STE 200, WASHINGTON, DC 20005 SN 0006-3568 J9 BIOSCIENCE JI Bioscience PD JUN PY 1992 VL 42 IS 6 BP 396 EP 396 DI 10.2307/1311854 PG 1 WC Biology SC Life Sciences & Biomedicine - Other Topics GA HW245 UT WOS:A1992HW24500002 ER PT J AU VITOUSEK, PM MATSON, PA AF VITOUSEK, PM MATSON, PA TI TROPICAL FORESTS AND TRACE GASES - POTENTIAL INTERACTIONS BETWEEN TROPICAL BIOLOGY AND THE ATMOSPHERIC SCIENCES SO BIOTROPICA LA English DT Article DE ATMOSPHERE; ECOSYSTEM; FOREST; GAS; NITROUS OXIDE; NUTRIENTS; OZONE; SOIL FERTILITY; TROPOSPHERE; TROPICS ID AMAZON BOUNDARY-LAYER; NITROUS-OXIDE; NUTRIENT DYNAMICS; EMISSIONS; METHANE; OZONE; FLOODPLAIN; ECOSYSTEMS; BASIN; FLUX AB Tropical forests are major contributors to the composition of the atmosphere, and anthropogenic changes to tropical ecosystems have driven changes in the atmosphere. Tropical biologists can make and have made significant contributions to understanding these effects, but we can also learn a great deal from the atmospheric sciences. In this paper, we show how knowledge about the functioning of tropical ecosystems can contribute to building a global source budget for a greenhouse gas (nitrous oxide), and how accumulating information from atmospheric measurements suggests that increased concentrations of a reactive gas (tropospheric ozone) represent a significant perturbation to tropical ecosystems-even in remote areas. C1 NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035. RP VITOUSEK, PM (reprint author), STANFORD UNIV,DEPT BIOL SCI,STANFORD,CA 94305, USA. NR 49 TC 13 Z9 13 U1 0 U2 6 PU ASSN TROP BIOL PI ST LOUIS PA MISSOURI BOTANICAL GARDEN 2345 TOWER GROVE AVE, ST LOUIS, MO 63110 SN 0006-3606 J9 BIOTROPICA JI Biotropica PD JUN PY 1992 VL 24 IS 2 BP 233 EP 239 DI 10.2307/2388517 PN B PG 7 WC Ecology SC Environmental Sciences & Ecology GA JB550 UT WOS:A1992JB55000003 ER PT J AU KLAES, KD DENTREMONT, RP THOMASON, LW AF KLAES, KD DENTREMONT, RP THOMASON, LW TI APPLYING AN 8-BIT MULTISPECTRAL COLOR-COMPOSITE IMAGE SIMULATION TECHNIQUE TO OPERATIONAL REAL-TIME AVHRR DATA SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article AB The Geophysics Directorate's 8-bit multispectral color-composite image display technique has been installed on the Satellite Data Processing System at the German Military Geophysical Off ice in Traben-Trarbach, Germany. The technique simulates 24-bit full-color composites on 8-bit color workstations, combining image data from the NOAA multispectral Advanced Very High Resolution Radiometer. The real-time application of this technique to operational satellite data is discussed. C1 GERMAN MIL GEOPHYS OFF,W-5580 TRABEN TRARBACH,GERMANY. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. RP KLAES, KD (reprint author), PHILLIPS LAB,GEOPHYS DIRECTORATE,DIV ATMOSPHER SCI,SATELLITE METEOROL BRANCH,BEDFORD,MA 01731, USA. OI Thomason, Larry/0000-0002-1902-0840 NR 9 TC 0 Z9 1 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD JUN PY 1992 VL 73 IS 6 BP 766 EP 772 DI 10.1175/1520-0477(1992)073<0766:AABMCC>2.0.CO;2 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HZ588 UT WOS:A1992HZ58800002 ER PT J AU TIBBITS, GF KASHIHARA, H BRILL, RW AF TIBBITS, GF KASHIHARA, H BRILL, RW TI MYOCARDIAL SARCOLEMMA ISOLATED FROM SKIPJACK TUNA, KATSUWONUS-PELAMIS SO CANADIAN JOURNAL OF ZOOLOGY LA English DT Article ID SARCOPLASMIC-RETICULUM; CARDIAC-MUSCLE; CALCIUM-CHANNEL; CA-2+ TRANSPORT; RELEASE; CONTRACTILITY; ACTIVATION; INHIBITION; MODULATION; VESICLES AB The high cardiac outputs observed in tuna compared with other teleosts may imply differences in the regulation of myocardial contractility. Sarcolemma is a critical organelle in the teleost heart in the regulation of intracellular calcium concentration and hence contractility. A procedure is described for the isolation of large quantities of highly purified sarcolemma from the skipjack tuna heart by differential and sucrose-gradient centrifugation in the presence of multiple protease inhibitors. The preparation was characterized using the sarcolemma marker K+-stimulated p-nitrophenylphosphatase (K+pNPPase). From a starting ventricular wet weight of about 60 g, a yield of >20 mg sarcolemmal protein and a >43-fold purification over the crude homogenate were achieved. The percentage recovery of the total K+pNPPase in the sarcolemma fraction was greater than 14%. Both the purification index and recovery were substantially greater than those achieved with a much smaller scale sarcolemma preparation recently described for the trout heart. The equilibrium binding of the dihydropyridine PN200-110 and ryanodine were determined in these preparations. In purified sarcolemma, the dihydropyridine receptor binding density (B(max)) and dissociation constant (K(d)) were found to be 0.48 +/- 0.07 pmol . mg protein-1 and 0.09 nM respectively, similar to that found in mammals. In crude homogenates, the ryanodine receptor B(max) was approximately 0. 12 +/- 0.04 pmol . mg protein-1 and thus was a little more than half the value observed for the dihydropyridine receptor. The large-scale sarcolemma isolation procedure described in this paper for tuna may be useful for developing a better understanding of the role of the sarcolemma in the regulation of ventricular function in teleosts. C1 NOAA, NATL MARINE FISHERIES SERV, SW FISHERIES SCI CTR, HONOLULU LAB, HONOLULU, HI 96822 USA. RP SIMON FRASER UNIV, SCH KINESIOL, CARDIAC MEMBRANE RES LAB, BURNABY V5A 1S6, BC, CANADA. NR 29 TC 9 Z9 9 U1 0 U2 0 PU CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS PI OTTAWA PA 65 AURIGA DR, SUITE 203, OTTAWA, ON K2E 7W6, CANADA SN 0008-4301 EI 1480-3283 J9 CAN J ZOOL JI Can. J. Zool. PD JUN PY 1992 VL 70 IS 6 BP 1240 EP 1245 DI 10.1139/z92-171 PG 6 WC Zoology SC Zoology GA JG563 UT WOS:A1992JG56300022 ER PT J AU KEEN, JE FARRELL, AP TIBBITS, GF BRILL, RW AF KEEN, JE FARRELL, AP TIBBITS, GF BRILL, RW TI CARDIAC PHYSIOLOGY IN TUNAS .2. EFFECT OF RYANODINE, CALCIUM, AND ADRENALINE ON FORCE FREQUENCY RELATIONSHIPS IN ATRIAL STRIPS FROM SKIPJACK TUNA, KATSUWONUS-PELAMIS SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID SARCOPLASMIC-RETICULUM; RAINBOW-TROUT; MYOCARDIAL SARCOLEMMA; HEART VENTRICLE; TELEOST HEARTS; FROG-HEART; MUSCLE; FISH; CONTRACTION; RESPONSES AB Force - frequency relationships and the dependence upon extracellular calcium as a source of activator calcium were investigated using atrial strips from the skipjack tuna (Katsuwonus pelamis). At 25-degrees-C, active force generation increased over a stimulation range of 0.2 - 1.6 Hz and declined at higher stimulation frequencies. Ryanodine, a blocker of calcium release from the sarcoplasmic reticulum, decreased active force by approximately 30 % but did not alter the shape of the force - frequency curve. Uniform contractions were maintained up to stimulation rates of 3.0 Hz following ryanodine application, compared with 3.4 Hz under control conditions. Active force increased with increasing extracellular calcium concentration in a concentration-dependent manner with greatest sensitivity over the range of 1.0 - 5.0 mM calcium. Activation duration decreased with increasing extracellular calcium concentrations up to 5.0 mM and with increasing contraction frequency up to 1.0 Hz. Relaxation duration also was reduced with increasing extracellular calcium over a range of 0.5 - 4.0 mM, and over a stimulation range of 0.2 - 0.6 Hz. Adrenaline increased active force threefold over the range of 10(-8) to 10(-5) M, with an EC50 value of 4.90 +/- 0.57 x 10(-7) M. The EC50 value was not dependent upon stimulation frequency. These results indicate that contraction in the skipjack tuna atrium is partially dependent upon intracellular calcium release from the sarcoplasmic reticulum. In this manner, the tuna heart more closely resembles the mammalian model of excitation-contraction coupling than that suggested for other fishes in which activator calcium is almost exclusively derived from extracellular influx. C1 SIMON FRASER UNIV,CARDIAC MEMBRANE RES LAB,BURNABY V5A 1S6,BC,CANADA. NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. RP KEEN, JE (reprint author), SIMON FRASER UNIV,DEPT BIOL SCI,BURNABY V5A 1S6,BC,CANADA. NR 44 TC 55 Z9 55 U1 0 U2 6 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD JUN PY 1992 VL 70 IS 6 BP 1211 EP 1217 DI 10.1139/z92-168 PG 7 WC Zoology SC Zoology GA JG563 UT WOS:A1992JG56300019 ER PT J AU MATHIEUCOSTELLO, O AGEY, PJ LOGEMANN, RB BRILL, RW HOCHACHKA, PW AF MATHIEUCOSTELLO, O AGEY, PJ LOGEMANN, RB BRILL, RW HOCHACHKA, PW TI CAPILLARY FIBER GEOMETRICAL RELATIONSHIPS IN TUNA RED MUSCLE SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID SKELETAL-MUSCLE; FINE-STRUCTURE; TELEOST FISH; VASCULARIZATION; ULTRASTRUCTURE; ANISOTROPY; PECTORALIS; VERTEBRATE; LENGTH; PIGEON AB The aim of this study was to examine the size and geometry of the capillary network in tuna red muscle, one of the most aerobic muscles in fish. Deep red muscle of 1.5- to 2-kg skipjack tuna, Katsuwonus pelamis, was perfusion fixed in situ, processed for electron microscopy, and analyzed by morphometry. Fiber cross-sectional area was 560 +/- 30 (SE)-mu-m2 in the samples. Capillary length per fiber volume was 4143 +/- 242 (SE) mm-2 and mitochondrial volume density 28.5 +/- 1.0 (SE) %. Indexes of capillarity such as average number of capillaries around a fiber, capillary length and surface per fiber volume, and capillary surface per fiber surface were high for a fish muscle. In fact, the size of the capillary - fiber interface (i.e., capillary to fiber surface) at a given mitochondrial volume per fiber was not significantly different in tuna red muscle compared with rat soleus muscle. However, calculation of mitochondrial respiratory rates in tuna red muscle yielded a substantially lower value (approximately 1/20th) compared with muscles of mammals. Besides the possible effect of differences in operating temperatures and (or) mitochondrial function(s) in fish compared with mammals, this suggests that the large capillary - fiber interface in tuna may be related to functions other than oxygen delivery per se, such as substrate and (or) heat transfer between capillaries and muscle fiber. C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. UNIV BRITISH COLUMBIA,DEPT ZOOL,VANCOUVER V6T 2A9,BC,CANADA. RP MATHIEUCOSTELLO, O (reprint author), UNIV CALIF SAN DIEGO,DEPT MED,LA JOLLA,CA 92093, USA. NR 50 TC 23 Z9 23 U1 1 U2 5 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD JUN PY 1992 VL 70 IS 6 BP 1218 EP 1229 DI 10.1139/z92-169 PG 12 WC Zoology SC Zoology GA JG563 UT WOS:A1992JG56300020 ER PT J AU ARTHUR, PG WEST, TG BRILL, RW SCHULTE, PM HOCHACHKA, PW AF ARTHUR, PG WEST, TG BRILL, RW SCHULTE, PM HOCHACHKA, PW TI RECOVERY METABOLISM OF SKIPJACK TUNA (KATSUWONUS-PELAMIS) WHITE MUSCLE - RAPID AND PARALLEL CHANGES IN LACTATE AND PHOSPHOCREATINE AFTER EXERCISE SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID INTRACELLULAR ACID-BASE; EXHAUSTIVE EXERCISE; SKELETAL-MUSCLE; RAINBOW-TROUT; GLYCOGEN-SYNTHESIS; PH; GLUCONEOGENESIS; SUBSTRATE; TRANSPORT; CAPACITY AB Lactate, glycogen, and high-energy phosphate levels were measured in serial biopsies from tuna white muscle during recovery from 15 min of enforced swimming. Exercise caused glycogen and phosphocreatine levels to decrease sharply and lactate concentration to increase markedly (up to 150-mu-mol . g-1). Lactate was cleared from white muscle in less than 90 min, at rates comparable to those seen in mammals (about 1.3-mu-mol . g-1 . min-1), and this was accompanied by nearly stoichiometric increases in white muscle glycogen (2 lactate : 1 glucosyl unit). The plasma lactate concentration remained elevated (35 - 40 mM) until lactate clearance from white muscle was completed, whereas the level of plasma glucose was constant (12 - 16 mM) for the entire 3-h recovery period. The exercise routine caused minimal changes in white muscle purine nucleotides apart from a slight, but significant, increase in IMP content. Transient changes in ATP appear to have resulted from short-term intense swimming activity noted during anesthetization. Unlike other teleosts, lactate clearance in tuna paralleled creatine rephosphorylation during recovery from exercise. We suggest that the postexercise adjustment of intracellular pH is responsible for this relationship. Lactate was seemingly metabolized within the white muscle mass, as indicated by in situ conservation of lactate carbon apparent from stiochiometric increases in white muscle glycogen levels. This prospect is discussed in view of low estimates of lactate utilization rates by other tissues and contrasted with expected high rates of whole-body lactate turnover during recovery. C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. STANFORD UNIV,DEPT BIOL SCI,STANFORD,CA 94305. RP ARTHUR, PG (reprint author), UNIV BRITISH COLUMBIA,DEPT ZOOL,VANCOUVER V6T 2A9,BC,CANADA. OI Arthur, Peter/0000-0002-1257-8200; Schulte, Patricia/0000-0002-5237-8836 NR 45 TC 56 Z9 57 U1 0 U2 7 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD JUN PY 1992 VL 70 IS 6 BP 1230 EP 1239 DI 10.1139/z92-170 PG 10 WC Zoology SC Zoology GA JG563 UT WOS:A1992JG56300021 ER PT J AU MOYES, CD MATHIEUCOSTELLO, OA BRILL, RW HOCHACHKA, PW AF MOYES, CD MATHIEUCOSTELLO, OA BRILL, RW HOCHACHKA, PW TI MITOCHONDRIAL METABOLISM OF CARDIAC AND SKELETAL-MUSCLES FROM A FAST (KATSUWONUS-PELAMIS) AND A SLOW (CYPRINUS-CARPIO) FISH SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID WHITE MUSCLE; ENERGY-METABOLISM; ENDURANCE EXERCISE; RESPIRATORY SYSTEM; LACTATE KINETICS; TUNA MUSCLES; RED; DESIGN; POWER; CAPACITY AB Tuna cardiac (atrium, compact and spongy ventricle) and skeletal muscle (red and white) were compared with carp tissues to determine the importance of mitochondrial differences in supporting the high aerobic capacities in tuna. Mitochondria isolated from red muscle of both species oxidized each of the physiological fuels at similar rates per milligram of mitochondrial protein, when differences in assay temperature are considered. The highest rate of oxygen consumption by ventricle mitochondria was 2 times greater in tuna than carp. The maximal oxidation rates were 3-4 times higher in ventricle than red muscle in both species. Tuna tissues had as much as 30 - 80 % more mitochondrial protein per gram of tissue than carp. Morphometrically this was manifested as extremely densely packed mitochondrial cristae, rather than increased mitochondrial volume densities. In general, higher aerobic capacities of tuna ventricle and red muscle are primarily attributable to greater tissue mass and, to a lesser extent, differences in the nature or quantity of mitochondria per gram of tissue. Unlike ventricle and red muscle, tissues with relatively low mitochondrial contents in carp (white muscle, atrium) demonstrated several-fold higher mitochondrial contents in tuna. Enzyme analyses of tissue and isolated mitochondria suggest a greater dependence of tuna tissues on fatty acids as fuels. Activities of carnitine palmitoyl transferase (CPT) per milligram of protein were 2 - 2.5 times higher in tuna red muscle and ventricle mitochondria than in carp mitochondria from the same tissues. Whole tissue activity ratios of hexokinase/CPT, which indicate the relative importance of glucose and fatty acid metabolism, were 5 times higher in carp spongy ventricle and 12 times higher in carp compact ventricle. These data suggest that muscle aerobic capacity can be increased at several levels: tissue mass, mitochondrial -volume density, cristae surface density, and mitochondrial specific activity. Large differences observed between carp and tuna muscles are due to cumulative effects of several of these factors. C1 UNIV BRITISH COLUMBIA,DEPT ZOOL,VANCOUVER V6T 2A9,BC,CANADA. UNIV CALIF SAN DIEGO,DEPT MED,LA JOLLA,CA 92093. NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. NR 44 TC 75 Z9 75 U1 1 U2 20 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD JUN PY 1992 VL 70 IS 6 BP 1246 EP 1253 DI 10.1139/z92-172 PG 8 WC Zoology SC Zoology GA JG563 UT WOS:A1992JG56300023 ER PT J AU BUCK, LT BRILL, RW HOCHACHKA, PW AF BUCK, LT BRILL, RW HOCHACHKA, PW TI GLUCONEOGENESIS IN HEPATOCYTES ISOLATED FROM THE SKIPJACK TUNA (KATSUWONUS-PELAMIS) SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID FISHES AB Skipjack tuna (Katsuwonus pelamis) hepatocytes were isolated and determined to be viable based on trypan blue exclusion, energy charge, and lactate dehydrogenase leakage. Trypan blue staining and red blood cell contamination were always less than 0.1 %, and lactate dehydrogenase leakage remained less than 1 % at 25-degrees-C for 10 h. The energy charge for freshly isolated cells ranged from 0.65 to 0.74. Alanine (10 mM) gave higher rates of gluconeogenesis and oxidation than lactate: alanine rates were 3.17 0.65-mu-mol glucose/(g packed cells . h) and 9.1 +/- 1.19-mu-mol CO2/(g . h), whereas lactate rates were 0.47 +/- 0.08 and 1.8 +/- 0.27, respectively. Phosphoenolpyruvate carboxykinase was 30 % cytosolic and 70 % mitochondrial, a finding that is in agreement with the liver's ability to use both lactate and alanine as gluconeogenic substrates. If hepatic gluconeogenesis is the major route of lactate removal postexercise, it is estimated that recovery would require 3800 h! Therefore, tuna liver is not the major site of glucose resynthesis and lactate clearance following burst exercise. C1 NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,HONOLULU,HI 96822. RP BUCK, LT (reprint author), UNIV BRITISH COLUMBIA,DEPT ZOOL,VANCOUVER V6T 2A9,BC,CANADA. NR 15 TC 7 Z9 7 U1 0 U2 1 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4301 J9 CAN J ZOOL JI Can. J. Zool.-Rev. Can. Zool. PD JUN PY 1992 VL 70 IS 6 BP 1254 EP 1257 DI 10.1139/z92-173 PG 4 WC Zoology SC Zoology GA JG563 UT WOS:A1992JG56300024 ER PT J AU KOSTER, RD JOUZEL, J SUOZZO, RJ RUSSELL, GL AF KOSTER, RD JOUZEL, J SUOZZO, RJ RUSSELL, GL TI ORIGIN OF JULY ANTARCTIC PRECIPITATION AND ITS INFLUENCE ON DEUTERIUM CONTENT - A GCM ANALYSIS SO CLIMATE DYNAMICS LA English DT Article ID GENERAL-CIRCULATION MODEL; ICE CORE; CLIMATE; CYCLE AB The NASA/GISS GCM is used to estimate the evaporative contributions of several oceanic regions (defined by temperature) to Antarctica's July precipitation. Tracer diagnostics in the GCM suggest that the weighted average evaporative source temperature for Antarctic precipitation as a whole is about 12-degrees-C. The average source temperature for local precipitation there varies from 9-degrees-C to 14-degrees-C. To examine the effect of evaporative source on water isotope concentration, the GCM also follows a global deuterium (HDO) tracer and deuterium tracers evaporating from each oceanic region. The results suggest that although evaporative source temperature does affect the concentrations of the individual HDO tracers, differences in evaporative source do not explain the scatter in the roughly linear relationship between condensation temperature and isotope concentration. C1 CEA DSM DPHG,GEOCHIM ISOTOP LAB,F-91191 GIF SUR YVETTE,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP KOSTER, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. RI Koster, Randal/F-5881-2012 OI Koster, Randal/0000-0001-6418-6383 NR 27 TC 41 Z9 41 U1 0 U2 6 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0930-7575 J9 CLIM DYNAM JI Clim. Dyn. PD JUN PY 1992 VL 7 IS 4 BP 195 EP 203 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JC118 UT WOS:A1992JC11800004 ER PT J AU SHUEN, JS YANG, V HSIAO, CC AF SHUEN, JS YANG, V HSIAO, CC TI COMBUSTION OF LIQUID-FUEL DROPLETS IN SUPERCRITICAL CONDITIONS SO COMBUSTION AND FLAME LA English DT Article ID PHASE-EQUILIBRIUM CALCULATIONS; MODIFIED SOAVE EQUATION; MIXTURES; DENSITIES; SYSTEMS; STATE AB A comprehensive analysis of liquid-fuel droplet combustion in both subcritical and supercritical environments has been conducted. The formulation is based on the complete conservation equations for both gas and liquid phases, and accommodates variable thermophysicai properties, finite-rate chemical kinetics, and a full treatment of liquid-vapor phase equilibrium at the droplet surface. The governing equations and associated interfacial boundary conditions are solved numerically using a fully coupled, implicit scheme with the dual time-stepping integration technique. The model is capable of treating the entire droplet history, including the transition from the subcritical to supercritical state. As a specific example, the combustion of n-pentane fuel droplets in air is studied for pressures in the range of 5- 140 atm. Results indicate that the ambient gas pressure exerts significant control of droplet gasification and burning processes through its influence on fluid transport, gas-liquid interfacial thermodynamics, and chemical reactions. The droplet gasification rate increases progressively with pressure. However, the data for the overall burnout time exhibit a considerable change in the combustion mechanism at the critical pressure, mainly as a result of reduced mass diffusivity and latent heat of vaporization with increased pressure. The influence of droplet size on the burning characteristics is also noted. C1 PENN STATE UNIV,DEPT MECH ENGN,UNIV PK,PA 16802. SVERDRUP TECHNOL INC,NASA,LEWIS RES CTR,CLEVELAND,OH 44142. NR 30 TC 58 Z9 60 U1 1 U2 13 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD JUN PY 1992 VL 89 IS 3-4 BP 299 EP 319 DI 10.1016/0010-2180(92)90017-J PG 21 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA HY306 UT WOS:A1992HY30600005 ER PT J AU CAPPELLA, JN PALMER, MT AF CAPPELLA, JN PALMER, MT TI THE EFFECT OF PARTNERS CONVERSATION ON THE ASSOCIATION BETWEEN ATTITUDE SIMILARITY AND ATTRACTION SO COMMUNICATION MONOGRAPHS LA English DT Article ID INTERPERSONAL-ATTRACTION; BEHAVIORS C1 NASA,AMES,CA. NORTHWESTERN UNIV,EVANSTON,IL 60201. RP CAPPELLA, JN (reprint author), UNIV PENN,ANNENBERG SCH COMMUNICAT,PHILADELPHIA,PA 19104, USA. NR 22 TC 9 Z9 9 U1 0 U2 3 PU SPEECH COMMUNICATION ASSN PI ANNANDALE PA 5105 BACKLICK RD, ANNANDALE, VA 22003 SN 0363-7751 J9 COMMUN MONOGR JI Commun. Monogr. PD JUN PY 1992 VL 59 IS 2 BP 180 EP 189 PG 10 WC Communication SC Communication GA HV218 UT WOS:A1992HV21800005 ER PT J AU RAY, RD HANSEN, RO AF RAY, RD HANSEN, RO TI A COMPUTER-PROGRAM TO PERFORM THE UPWARD CONTINUATION OF POTENTIAL-FIELD DATA BETWEEN ARBITRARY SURFACES - COMMENT SO COMPUTERS & GEOSCIENCES LA English DT Letter C1 COLORADO SCH MINES,DEPT GEOPHYS,GOLDEN,CO 80401. RP RAY, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,STX,CODE 926,GREENBELT,MD 20771, USA. RI Ray, Richard/D-1034-2012 NR 5 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0098-3004 J9 COMPUT GEOSCI JI Comput. Geosci. PD JUN PY 1992 VL 18 IS 5 BP 619 EP 622 DI 10.1016/0098-3004(92)90099-D PG 4 WC Computer Science, Interdisciplinary Applications; Geosciences, Multidisciplinary SC Computer Science; Geology GA JG197 UT WOS:A1992JG19700010 ER PT J AU SJOGREN, JA AF SJOGREN, JA TI CLOSED-FORM SOLUTION OF DECOMPOSABLE STOCHASTIC-MODELS SO COMPUTERS & MATHEMATICS WITH APPLICATIONS LA English DT Article AB Markov and semi-Markov processes are increasingly being used in the modeling of complex reconfigurable systems (fault-tolerant computers). The estimation of the reliability (or some measure of performance) of the system reduces to solving the process for its state probabilities. Such a model may exhibit numerous states and complicated transition distributions, contributing to an expensive and numerically delicate solution procedure. Thus, when a system exhibits a decomposition property, either structurally (autonomous subsystems), or behaviorally (component failure versus reconfiguration), it is desirable to exploit this decomposition in the reliability calculation. In interesting cases there can be failure states which arise from non-failure states of the subsystems. We present equations which allow the computation of failure probabilities of the total (combined) model without requiring a complete solution of the combined model. This material is presented within the context of closed-form functional representation of probabilities as utilized in the Symbolic Hierarchical Automated Reliability and Performance Evaluator (SHARPE) tool. The techniques adopted enable one to compute such probability function for a much wider class of systems at a reduced computational cost. Several examples show how the method is used, especially in enhancing the versatility of the SHARPE tool. RP SJOGREN, JA (reprint author), USA,LANGLEY RES CTR,ARMY AVION RES & DEV ACTIV,HAMPTON,VA 23665, USA. NR 26 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0898-1221 J9 COMPUT MATH APPL JI Comput. Math. Appl. PD JUN PY 1992 VL 23 IS 12 BP 43 EP 67 DI 10.1016/0898-1221(92)90091-U PG 25 WC Computer Science, Interdisciplinary Applications; Mathematics, Applied SC Computer Science; Mathematics GA HR288 UT WOS:A1992HR28800004 ER PT J AU WANG, YJ SHIEH, LS SUNKEL, JW AF WANG, YJ SHIEH, LS SUNKEL, JW TI ROBUST STABILIZATION, ROBUST PERFORMANCE, AND DISTURBANCE ATTENUATION FOR UNCERTAIN LINEAR-SYSTEMS SO COMPUTERS & MATHEMATICS WITH APPLICATIONS LA English DT Article ID RICCATI EQUATION APPROACH; DESIGN METHODOLOGY; CONTROLLERS AB This paper present a linear quadratic regulator approach to the robust stabilization, robust performance, and disturbance attenuation of uncertain linear systems. The state-feedback designed systems provide both robust stability with optimal performance and disturbance attenuation with H infinity-norm bounds. The proposed approach can be applied to matched and/or mismatched uncertain linear systems. For a matched uncertain linear system, it is shown that the disturbance-attenuation robust-stabilizing controllers with or without optimal performance always exist and can be easily determined without searching; whereas, for a mismatched uncertain linear system, the introduced tuning parameters greatly enhance the flexibility of finding the disturbance-attenuation robust-stabilizing controllers. C1 UNIV HOUSTON,DEPT ELECT ENGN,UNIV PK,HOUSTON,TX 77204. NASA,LYNDON B JOHNSON SPACE CTR,DIV AVION SYST,HOUSTON,TX 77058. NR 15 TC 7 Z9 7 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0898-1221 J9 COMPUT MATH APPL JI Comput. Math. Appl. PD JUN PY 1992 VL 23 IS 11 BP 67 EP 80 DI 10.1016/0898-1221(92)90070-X PG 14 WC Mathematics, Applied SC Mathematics GA HN402 UT WOS:A1992HN40200008 ER PT J AU VACCA, JR AF VACCA, JR TI METAVIEWS COOPERATIVE PROCESSING IN THE MEDICAL AND PHARMACEUTICAL INDUSTRIES SO DOCUMENT & IMAGE AUTOMATION LA English DT Article AB This article offers a look at how medical and pharmaceutical firms are using the Metaview cooperative processing system from Metafile Information Systems (Rochester, MN). End-users report improved productivity, reduced system costs, recovery of valuable physical storage space and a significant reduction in the number of manual files to maintain. The author offers his thoughts about several critical challenges to the implementation of document imaging systems: performance, human factors, availability, and advanced functions and features. C1 NASA,SPACE STN FREEDOM PROGRAM OFF,RESTON,VA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PHILIPS BUSINESS INFOR PI POTOMAC PA 1201 SEVEN LOCKS RD, POTOMAC, MD 20854 SN 1071-6130 J9 DOC IMAGE AUTOM PD SUM PY 1992 VL 12 IS 2 BP 8 EP 15 PG 8 WC Computer Science, Information Systems; Imaging Science & Photographic Technology SC Computer Science; Imaging Science & Photographic Technology GA JD843 UT WOS:A1992JD84300002 ER PT J AU MATSON, PA HUNTER, MD AF MATSON, PA HUNTER, MD TI THE RELATIVE CONTRIBUTIONS OF TOP-DOWN AND BOTTOM-UP FORCES IN POPULATION AND COMMUNITY ECOLOGY SO ECOLOGY LA English DT Editorial Material DE BOTTOM-UP FORCES; COMMUNITY STRUCTURE; DONOR-CONTROL; FOOD WEBS; HETEROGENEITY; KEYSTONE SPECIES; TOP-DOWN FORCES; TROPHIC CASCADE C1 PENN STATE UNIV,DEPT ENTOMOL,UNIV PK,PA 16802. RP MATSON, PA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 100 Z9 103 U1 3 U2 38 PU ECOLOGICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE, NW, STE 400, WASHINGTON, DC 20036 SN 0012-9658 J9 ECOLOGY JI Ecology PD JUN PY 1992 VL 73 IS 3 BP 723 EP 723 DI 10.2307/1940151 PG 1 WC Ecology SC Environmental Sciences & Ecology GA HU767 UT WOS:A1992HU76700001 ER PT J AU LOWMAN, PD AF LOWMAN, PD TI GEOPHYSICS FROM ORBIT - THE UNEXPECTED SURPRISE SO ENDEAVOUR LA English DT Article ID CRUST AB The achievements of space exploration in gaining new knowledge of the outer Universe have been well publicized. Rather less well known is the light that space flight has thrown on the nature, in geophysical terms, of the solid Earth. This article reviews what has been learnt since the late 1950s, both what is firmly based and what is still controversial. RP NASA, GODDARD SPACE FLIGHT CTR, GEODYNAM BRANCH, GREENBELT, MD 20771 USA. NR 23 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0160-9327 EI 1873-1929 J9 ENDEAVOUR JI Endeavour PD JUN PY 1992 VL 16 IS 2 BP 50 EP 58 DI 10.1016/0160-9327(92)90002-7 PG 9 WC History & Philosophy Of Science; Multidisciplinary Sciences SC History & Philosophy of Science; Science & Technology - Other Topics GA JC972 UT WOS:A1992JC97200002 ER PT J AU BRAUN, MJ CANACCI, VA RUSSELL, LM AF BRAUN, MJ CANACCI, VA RUSSELL, LM TI FULL FIELD FLOW VISUALIZATION AND COMPUTER-AIDED VELOCITY-MEASUREMENTS IN A BANK OF CYLINDERS IN A WIND-TUNNEL SO EXPERIMENTS IN FLUIDS LA English DT Article ID ARRAY AB The full field flow tracking (FFFT) method that is presented in this paper uses a laser-generated, mechanically strobed planar sheet of light, a low luminosity TV camera coupled with a long distance microscope, and a computer-controlled videorecorder to study non-intrusively and qualitatively the flow structures in a bank of cylinders that are placed in a wind tunnel. This setup simulates an upscale version of the geometry of internal cooling passageways characteristic of small air-cooled radial turbines. The qualitative images supplied by the FFFT system are processed by means of a computer-integrated image quantification (CIIQ) method into quantitative information, trajectories and velocities, that describes the flow upstream of and within the bank of cylinders. The tracking method is lagrangian in concept, and permits identification and tracking of the same particle, thus facilitating construction of time dependent trajectories and the calculation of true velocities and accelerations. The error analysis evaluates the accuracy with which the seed particles follow the flow and the errors incurred during the quantitative processing of the raw data derived from the FFFT/CIIQ method. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BRAUN, MJ (reprint author), UNIV AKRON,DEPT MECH ENGN,AKRON,OH 44325, USA. NR 36 TC 6 Z9 6 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD JUN PY 1992 VL 13 IS 2-3 BP 117 EP 127 DI 10.1007/BF00218157 PG 11 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA JB085 UT WOS:A1992JB08500006 ER PT J AU REYNOLDS, AP AF REYNOLDS, AP TI CONSTANT AMPLITUDE AND POST-OVERLOAD FATIGUE CRACK-GROWTH BEHAVIOR IN PM ALUMINUM-ALLOY AA-8009 SO FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES LA English DT Article ID PROPAGATION; MORPHOLOGY; CLOSURE AB The fatigue crack growth behavior of a recently developed, rapidly solidified, powder metallurgy, dispersion strengthened aluminum alloy, AA 8009, was studied at room temperature in laboratory air. Constant amplitude/constant DELTA-K and single spike overload conditions were examined. Alloy 8009 exhibited high fatigue crack growth rates and low closure levels in comparison to typical ingot processed aluminum alloys. It was proposed that minimal crack roughness and crack path deflection, along with limited slip reversibility, resulting from the ultra-fine microstructure were responsible for the relatively poor (versus ingot processed aluminum alloys) da/dN versus DELTA-K performance of AA 8009. RP REYNOLDS, AP (reprint author), NASA,LANGLEY RES CTR,MS 188A,HAMPTON,VA 23665, USA. RI Reynolds, Anthony/F-2585-2010 NR 21 TC 10 Z9 10 U1 0 U2 4 PU FATIGUE & FRACTURE ENGINEERINGMATERIALS STRUCTURES LIMITED PI SHEFFIELD PA C/O SIRIUS UNIV OF SHEFFIELD/FAC OF ENG MAPPIN STREET, SHEFFIELD, S YORKSHIRE, ENGLAND S1 3JD SN 8756-758X J9 FATIGUE FRACT ENG M JI Fatigue Fract. Eng. Mater. Struct. PD JUN PY 1992 VL 15 IS 6 BP 551 EP 562 DI 10.1111/j.1460-2695.1992.tb01294.x PG 12 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA JB919 UT WOS:A1992JB91900003 ER PT J AU NYQUIST, LE SHIH, CY AF NYQUIST, LE SHIH, CY TI THE ISOTOPIC RECORD OF LUNAR VOLCANISM SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID MARE BASALTS; MELT ROCKS; PETROGENESIS; AGES; GEOCHRONOLOGY; EVOLUTION; ORIGIN; CLASTS; KREEP; CRUST AB The timing and extent of lunar volcanism was determined primarily by the internal thermal evolution of the moon. A late, heavy bombardment produced most of the observable lunar basins, easily recognized stratigraphic markers, and also may have influenced lunar volcanism. Most of the nearside basins seem to have been produced 3.8-4.0 Ga ago, during a period often referred to as the lunar cataclysm. The pre-cataclysm period was characterized by formation of the lunar crust, plutonic rocks within the crust, and pre-mare volcanism. Isotopic analysis of breccia clasts pre-dating the cataclysm has yielded an outline of this period. The isotopic record of post-cataclysm mare volcanism is clear but incomplete because samples from the youngest mare areas are lacking. Specifically, the isotopic data show that some lunar anorthosites formed approximately 4.45 Ga ago, consistent with early formation of an anorthositic lunar crust. Some "Mg-suite" norites, troctolites, and dunites also formed approximately contemporaneously with the oldest anorthosites, but others are up to 200-300 Ma younger. More evolved rocks (granites and quartz-monzodiorites) also formed between approximately 4.4 and approximately 4.0 Ga ago. The earliest known pre-mare volcanism at approximately 4.25 Ga ago included aluminous, mare-like basalts and an olivine gabbronorite similar to Apollo 12 basalts. KREEP basalt volcanism began at least approximately 4.1 Ga ago, approximately contemporaneously with that of the ancient, mare-like basalts, and continued during the cataclysm. Recorded instances of high-Ti mare basalt volcanism began during or immediately after the cataclysm. Low-Ti mare basalt volcanism is the most recent for which samples are available. The isotopic data record an early primary lunar differentiation during which mare basalt sources formed, probably by crystallization of cumulus minerals from a lunar magma ocean. The isotopic record of post-cataclysm basalts indicates a heterogeneous lunar mantle and can be explained by partial melting of cumulate sources, but more complex petrogenesis also has been suggested. More complex petrogenetic processes including assimilation and Assimilation-Fractional-Crystallization (AFC) seem to be required for pre-mare volcanics. The isotopic data contain a hint that petrogenesis of the oldest pre-mare volcanics may be linked to formation of the so-called "Procellarum Basin," possibly the oldest and largest lunar basin. Such a basin would provide a geologic context for the pre-mare volcanics, and its formation may have been a defining moment in lunar history. C1 LOCKHEED ENGN & SCI CO, HOUSTON, TX 77258 USA. RP NASA, LYNDON B JOHNSON SPACE CTR, SN4, HOUSTON, TX 77058 USA. NR 169 TC 179 Z9 183 U1 3 U2 19 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0016-7037 EI 1872-9533 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD JUN PY 1992 VL 56 IS 6 BP 2213 EP 2234 DI 10.1016/0016-7037(92)90185-L PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA HZ452 UT WOS:A1992HZ45200004 ER PT J AU DOZIER, J MOORE, B AF DOZIER, J MOORE, B TI EOS - SCIENCE AND POLICY PRIORITIES ARE SET FOR REMOTE-SENSING TECHNOLOGY SO GEOTIMES LA English DT Article RP DOZIER, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Dozier, Jeff/B-7364-2009 OI Dozier, Jeff/0000-0001-8542-431X NR 0 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOLOGICAL INST PI ALEXANDRIA PA 4220 KING ST, ALEXANDRIA, VA 22302-1507 SN 0016-8556 J9 GEOTIMES JI Geotimes PD JUN PY 1992 VL 37 IS 6 BP 12 EP 15 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HX329 UT WOS:A1992HX32900006 ER PT J AU YAMAMOTO, A KEIL, LC REID, IA AF YAMAMOTO, A KEIL, LC REID, IA TI EFFECT OF INTRARENAL BRADYKININ INFUSION ON VASOPRESSIN RELEASE IN RABBITS SO HYPERTENSION LA English DT Article; Proceedings Paper CT 45TH ANNUAL FALL CONF AND SCIENTIFIC SESSION OF THE COUNCIL FOR HIGH BLOOD PRESSURE RESEARCH CY SEP 24-27, 1991 CL CHICAGO, IL SP COUNCIL HIGH BLOOD PRESSURE RES DE RENAL NERVES; VASOPRESSIN; CHEMORECEPTORS; BRADYKININ; RABBIT STUDIES ID AFFERENT RENAL NERVES; ARTERIAL MECHANORECEPTORS; RAT; DISCHARGES; PLASMA; KIDNEY; CHEMORECEPTORS; STIMULATION; RECEPTORS; NEURONS AB Electrical stimulation of afferent renal nerves and activation of renal mechanoreceptors increase plasma vasopressin concentration. In the present study, the effect of renal chemoreceptor activation on plasma vasopressin concentration was investigated in anesthetized rabbits. Renal chemoreceptors were activated with intrarenal infusions of bradykinin. With intrarenal infusion of bradykinin at 136 ng/min, plasma vasopressin concentration increased from 4.5+/-1.5 to 26.8+/-14.2 pg/ml at 5 minutes (p<0.01), whereas with infusion at 1,360 ng/min, plasma vasopressin increased from 5.9+/-2.0 to 54.4+/-16.4 pg/ml at 5 minutes (p<0.01). There was no significant change in plasma vasopressin during intravenous infusion of bradykinin at 136 ng/min. Infusion at 1,360 ng/min increased plasma vasopressin from 2.7+/-0.5 to 14.8+/-6.4 pg/ml (p<0.01), but this increase was significantly less than that produced by intrarenal infusion of the same dose of bradykinin. Similar effects on plasma vasopressin were observed during paired intrarenal and intravenous infusions of bradykinin at 136 ng/min. Renal denervation markedly reduced the vasopressin responses to intrarenal infusion of bradykinin at 136 ng/min (2.8+/-0.5 to 4.0+/-0.7 pg/ml, p<0.01) and 1,360 ng/min (3.2+/-0.7 to 7.8+/-1.8 pg/ml, p<0.05). These results indicate that bradykinin stimulates vasopressin release by an intrarenal action and suggest that this action is mediated by afferent renal nerves. C1 UNIV CALIF SAN FRANCISCO,DEPT PHYSIOL,BOX 0444,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. FU NHLBI NIH HHS [HL-29714] NR 34 TC 11 Z9 11 U1 0 U2 1 PU AMER HEART ASSOC PI DALLAS PA 7272 GREENVILLE AVENUE, DALLAS, TX 75231-4596 SN 0194-911X J9 HYPERTENSION JI Hypertension PD JUN PY 1992 VL 19 IS 6 BP 799 EP 803 PN 2 PG 5 WC Peripheral Vascular Disease SC Cardiovascular System & Cardiology GA HX023 UT WOS:A1992HX02300041 PM 1592484 ER PT J AU LYNCH, DK HANNER, MS RUSSELL, RW AF LYNCH, DK HANNER, MS RUSSELL, RW TI 8-13 MU-M SPECTROSCOPY AND IR PHOTOMETRY OF COMET P/BRORSEN-METCALF (1989O) NEAR PERIHELION SO ICARUS LA English DT Article ID DUST COMA; HALLEY; AIRBORNE; EMISSION C1 JET PROP LAB,PASADENA,CA 91109. RP LYNCH, DK (reprint author), AEROSPACE CORP,CTR SPACE & ENVIRONM TECHNOL,POB 92957,MAIL STOP M2-266,LOS ANGELES,CA 90009, USA. NR 33 TC 14 Z9 14 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUN PY 1992 VL 97 IS 2 BP 269 EP 275 DI 10.1016/0019-1035(92)90133-R PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JD226 UT WOS:A1992JD22600009 ER PT J AU JIN, JM VOLAKIS, JL YU, CL WOO, AC AF JIN, JM VOLAKIS, JL YU, CL WOO, AC TI MODELING OF RESISTIVE SHEETS IN FINITE-ELEMENT SOLUTIONS SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note ID SCATTERING; STRIPS AB A formulation is presented for modeling a resistive card in the context of the finite element method (FEM). The appropriate variational expression is proposed, and for validation purposes results are presented for the scattering by a metal-backed cavity loaded with a resistive card. C1 PACIFIC MISSILE TEST CTR,POINT MUGU,CA 93042. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP JIN, JM (reprint author), UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109, USA. NR 9 TC 14 Z9 14 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD JUN PY 1992 VL 40 IS 6 BP 727 EP 731 DI 10.1109/8.144609 PG 5 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA JB672 UT WOS:A1992JB67200019 ER PT J AU BAYARD, DS AF BAYARD, DS TI TRANSIENT ANALYSIS OF AN ADAPTIVE SYSTEM FOR OPTIMIZATION OF DESIGN PARAMETERS SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note AB In this note, averaging methods are applied to analyzing and optimizing the transient response associated with the direct adaptive control of an oscillatory second-order minimum-phase system. RP BAYARD, DS (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 22 TC 0 Z9 0 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD JUN PY 1992 VL 37 IS 6 BP 842 EP 848 DI 10.1109/9.256361 PG 7 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA HW459 UT WOS:A1992HW45900022 ER PT J AU DEMERDASH, NA WANG, R SECUNDE, R LISE LEHMANN SHAH, MR NEHL, TW HOOLE, SRH BRAUER, JR AF DEMERDASH, NA WANG, R SECUNDE, R LISE LEHMANN SHAH, MR NEHL, TW HOOLE, SRH BRAUER, JR TI 3-DIMENSIONAL MAGNETIC-FIELDS IN EXTRA HIGH-SPEED MODIFIED LUNDELL ALTERNATORS COMPUTED BY A COMBINED VECTOR-SCALAR MAGNETIC POTENTIAL FINITE-ELEMENT METHOD SO IEEE TRANSACTIONS ON ENERGY CONVERSION LA English DT Article DE 3-DIMENSIONAL FINITE ELEMENTS; 3-DIMENSIONAL MAGNETIC FIELDS; MODIFIED LUNDELL ALTERNATORS; MAGNETIC VECTOR AND SCALAR POTENTIALS ID COMPUTATIONS; MACHINERY AB A three dimensional (3D) finite element (FE) approach was developed and implemented for computation of global magnetic fields in a 14.3 kVA modified Lundell alternator. The essence of the new method is the combined use of magnetic vector and scalar potential formulations in 3D finite elements. This approach makes it practical, using state of the art super-computer resources, to globally analyze magnetic fields and operating performances of rotating machines which have truly 3D magnetic flux patterns. The 3D-FE computed fields and machine inductances as well as various machine performance simulations of the 14.3 kVA machine are presented in this paper and its two companion papers. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. SIEMENS AG, DIV TURBINE GEN, BERLIN, GERMANY. GE, SCHENECTADY, NY 12345 USA. GM CORP, RES LABS, WARREN, MI 48090 USA. MACNEAL SCHWENDLER CORP, MILWAUKEE, WI USA. HARVEY MUDD COLL, CLAREMONT, CA 91711 USA. RP CLARKSON UNIV, DEPT ELECT & COMP ENGN, POTSDAM, NY 13676 USA. NR 28 TC 13 Z9 18 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0885-8969 EI 1558-0059 J9 IEEE T ENERGY CONVER JI IEEE Trans. Energy Convers. PD JUN PY 1992 VL 7 IS 2 BP 353 EP 366 DI 10.1109/60.136231 PG 14 WC Energy & Fuels; Engineering, Electrical & Electronic SC Energy & Fuels; Engineering GA HV168 UT WOS:A1992HV16800014 ER PT J AU FREILEY, AJ CONROY, BL HOPPE, DJ BHANJI, AM AF FREILEY, AJ CONROY, BL HOPPE, DJ BHANJI, AM TI DESIGN CONCEPTS OF A 1-MW CW X-BAND TRANSMIT-RECEIVE SYSTEM FOR PLANETARY RADAR SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB The conceptual design of the 1-MW X-Band Transmit System for the Goldstone Solar System Radar represents the next step in the quest to expand planetary radar explorations. The radar transmitter requirements are summarized. The characteristics and expected performance of the major elements are discussed, including the klystrons, power amplifiers, microwave transmission lines, feed systems, beam power supply, heat exchanger, phase stable exciter, and the monitor/control system. An assessment of the technology development needed to meet the system requirements is given, and possible areas of difficulty are outlined. RP FREILEY, AJ (reprint author), JET PROP LAB,TECH STAFF,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 1 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1047 EP 1055 DI 10.1109/22.141334 PG 9 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200002 ER PT J AU CORMIER, RA MIZUHARA, A AF CORMIER, RA MIZUHARA, A TI 250-KW CW KLYSTRON AMPLIFIER FOR PLANETARY RADAR SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Jet Propulsion Laboratory contracted with Varian Associates to design, build, and deliver replacements for VA-949J klystrons in the X-band planetary radar transmitter on the Goldstone, CA, 70-meter antenna. Output power was to be increased from 200 kW to 250 kW CW per klystron, and full dc beam power was to be dissipated in the collector (it is not possible to operate the VA-9496J without RF drive because of limited collector dissipation capability). Replacements were to be made with a minimum of transmitter modifications. Two model VKX-7864A klystrons were subsequently built and delivered. This report describes the design of these klystrons and the results of their performance testing. The planetary radar transmitter is now operating with these two klystrons. C1 VARIAN ASSOCIATES INC,MICROWAVE POWER TUBE PROD,PALO ALTO,CA 94303. RP CORMIER, RA (reprint author), JET PROP LAB,TECH STAFF,4800 GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 5 Z9 5 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1056 EP 1062 DI 10.1109/22.141335 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200003 ER PT J AU GOLDSTEIN, RM RANDOLPH, LW AF GOLDSTEIN, RM RANDOLPH, LW TI RINGS OF EARTH SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB We have used the planetary radar at the Jet Propulsion Laboratory's Goldstone Tracking Station to monitor small particles of orbital debris. This radar can detect metallic objects as small as 1.8 mm in diameter at an altitude of 600 km. The results of our first set of observations show a flux (at 600 km) of 6.4 objects per sq km per day, of equivalent size of 1.8 mm or larger. Forty percent of the observed particles appear to be concentrated into one or two orbits. An orbital ring with the same inclination as the radar (35.1-degrees) is suggested. However, an orbital band with the much higher inclination of 66-degrees is also a possibility. Neither explanation is without difficulty. RP GOLDSTEIN, RM (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 1 TC 4 Z9 4 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1077 EP 1080 DI 10.1109/22.141338 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200006 ER PT J AU CHAKRABORTY, D AF CHAKRABORTY, D TI A SPACE-BASED MICROWAVE RADAR CONCEPT SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB A Space-Based Microwave Radar (SBR) Concept is defined using a tether trans/receive antenna supported between two gravity gradient low earth-orbiting satellites. A cluster of four tether antennas each of 6 km maximum length and 1.5 km separation between tethers constitutes a radar. A system of 8 to 11 such clusters constitutes the overall radar scheme which will cover approximately one third of the earth surface for detecting sea-based targets. Issues identified are the array structure, coherence of tethered arrays, grating lobe energy clamping, clutter effects, communications, system requirements and the overall radar system concept including stability considerations. This paper presents the base-line definition of an alternate space-based radar scheme. A significant amount of R&D efforts will be required to derive practical solutions of the proposed scheme. RP CHAKRABORTY, D (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 0 Z9 0 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1081 EP 1089 DI 10.1109/22.141339 PG 9 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200007 ER PT J AU JOINER, J STEFFES, PG NOLL, KS AF JOINER, J STEFFES, PG NOLL, KS TI SEARCH FOR SULFUR (H2S) ON JUPITER AT MILLIMETER WAVELENGTHS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID GIANT PLANETS; ATMOSPHERE AB We have observed Jupiter at two wavelengths near 1.4 mm in an attempt to detect gaseous hydrogen sulfide (H2S) or place new upper limits on its abundance in Jupiter's atmosphere. Although we were not successful in detecting H2S, we report the first brightness temperature observations of Jupiter at 1.4 mm with a spectral resolution of approximately 1 GHz using Mars as the calibration standard. We also discuss the methodology and results of a laboratory experiment in which we measured H2S absorption at 1.4 mm in a simulated Jovian atmosphere (predominantly H-2 and He). We apply the results of our laboratory measurements to a radiative transfer model which we use to interpret our observations of Jupiter. C1 GEORGIA INST TECHNOL,DEPT ELECT ENGN,ATLANTA,GA 30332. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RI Joiner, Joanna/D-6264-2012 NR 27 TC 9 Z9 9 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1101 EP 1109 DI 10.1109/22.141341 PG 9 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200009 ER PT J AU ANTSOS, D CHEW, W RILEY, AL HUNT, BD FOOTE, MC BAJUK, LJ RASCOE, DL COOLEY, TW AF ANTSOS, D CHEW, W RILEY, AL HUNT, BD FOOTE, MC BAJUK, LJ RASCOE, DL COOLEY, TW TI MODELING OF PLANAR QUASI-TEM SUPERCONDUCTING TRANSMISSION-LINES SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Design oriented modeling of high-temperature superconducting thin-film microwave circuits is difficult when film thickness is of the order of the penetration depth of the fields. Involved formulas for loss, phase velocity and characteristic impedance [1] can be derived from the Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity. The parameters required by these formulas do not correspond to "readily measurable" observables that depend on the manufacturing process of the superconductor. In this paper an application of the phenomenological loss equivalence method [2] in modeling the microwave behavior of planar quasi-TEM superconducting transmission lines is presented. Measured and modeled S-parameters of an existing superconducting coplanar waveguide lowpass filter agree to within 0.3 dB in magnitude and 0.5 radians in phase. Extracted values for penetration depth and real part of the conductivity of the superconducting film are within 10% of the findings of other researchers. RP ANTSOS, D (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 12 TC 3 Z9 3 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1128 EP 1132 DI 10.1109/22.141344 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200012 ER PT J AU REGIER, FA AF REGIER, FA TI THE ACTS MULTIBEAM ANTENNA SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB The Advanced Communications Technology Satellite (ACTS) to be launched in 1993 introduces several new technologies including a multibeam antenna (MBA) operating at Ka-band. The satellite is introduced briefly, and then the MBA, consisting of electrically similar 30 GHz receive and 20 GHz transmit offset Cassegrain systems-both utilizing orthogonal linear polarizations, is described. Dual polarization is achieved by using one feed assembly for each polarization in conjunction with nested front and back subreflectors, the gridded front subreflector acting as a window for one polarization and a reflector for the other. The antennas produce spot beams with approximately 0.3 degree beamwidth and gains of approximately 50 dbi. High surface accuracy and high edge taper produce low sidelobe levels and high cross-polarization isolation. A brief description is given of several Ka-band components fabricated for ACTS. These include multiflare antenna feedhorns, beam-forming networks utilizing latching ferrite waveguide switches, a 30 GHz HEMT low-noise amplifier and a 20 GHz TWT power amplifier. RP REGIER, FA (reprint author), NASA,LEWIS RES CTR,ACTS PROJECT OFF,MS 54-6,CLEVELAND,OH 44135, USA. NR 4 TC 6 Z9 6 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1159 EP 1164 DI 10.1109/22.141347 PG 6 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200015 ER PT J AU HALL, JR HASTRUP, RC BELL, DJ AF HALL, JR HASTRUP, RC BELL, DJ TI MICROWAVE SYSTEMS APPLICATIONS IN DEEP SPACE TELECOMMUNICATIONS AND NAVIGATION - SPACE EXPLORATION INITIATIVE ARCHITECTURES SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB The United States Space Exploration Initiative (SEI) calls for the charting of a new and evolving manned course to the Moon, Mars, and beyond. The fundamental SEI support objectives are to provide the mission with means to monitor and control mission elements, acquire engineering, science, and navigation data, compute state vectors and navigate, and move these data efficiently and automatically between mission nodes for timely analysis and decision-making. Microwave links provide the means to communicate between system nodes, and the essential radio metrics to navigate; later, these likely will be augmented with optical links. Although these objectives do not depart, fundamentally, from those evolved over the past 30 years in supporting deep space robotic exploration, there are several new challenges. This paper first familiarizes the reader with the general mission telecommunications and navigation support requirements and resulting architectures for SEI mission support, and then discusses the implications of these on the role of microwave technology in these architectures, particularly for Mars exploration support. Effective use of microwave technology is enabling, and obviously the sine qua non of the mission support architecture. RP HALL, JR (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 TC 2 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1171 EP 1178 DI 10.1109/22.141349 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200017 ER PT J AU POWER, JL AF POWER, JL TI MICROWAVE ELECTROTHERMAL PROPULSION FOR SPACE SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID THRUSTER; PERFORMANCE; GAS AB The microwave electrothermal thruster (MET) is an attractive concept for medium or high power spacecraft propulsion. The heart of the concept lies in heating a propellant gas by passing it through a microwave plasma discharge. As described in the paper, the plasma is created in a resonant cavity by tuning either the TM(011) or the TM(012) mode for impedance-matched operation, using two internal tuning mechanisms. The MET concept is electrodeless, synergistically combines high pressure and high power capability, provides external control over the energy-conversion discharge, and operates on hydrogen propellant. Upwards of 95% efficiency has been reported in absorbing the applied microwave power in the plasma discharge. By employing a magnetic nozzle with the MET, substantial performance and life gains are expected due to reduced wall heating and losses, improved recovery of propellant internal energy, and discharge stabilization. Calculations of potential MET performance predict that 2000 sec. specific impulse at 6000 K average discharge chamber temperature and 1.0 MPa (10 atm.) pressure are reasonable goals with hydrogen propellant. Apparatus is described for testing the resonant-cavity MET to power levels of 30 kW at 915 MHz on nitrogen, helium, and hydrogen. It includes a superconducting magnet, providing field strengths to 5.7 T, to implement a magnetic nozzle. The low-ripple operation of the microwave generator has been verified, as has a procedure for starting the microwave discharge and raising the power applied to the cavity via a phase shifter-tuner. Impedance-matched resonant operation of the microwave cavity has been achieved. RP POWER, JL (reprint author), NASA,LEWIS RES CTR,DIV SPACE PROPULS TECHNOL,21000 BROOKPK RD,MS SPTD-1,CLEVELAND,OH 44135, USA. NR 17 TC 16 Z9 18 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1179 EP 1191 DI 10.1109/22.141350 PG 13 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200018 ER PT J AU MYSOOR, NR PERRET, JD KERMODE, AW AF MYSOOR, NR PERRET, JD KERMODE, AW TI AN X-BAND SPACECRAFT TRANSPONDER FOR DEEP SPACE APPLICATIONS - DESIGN CONCEPTS AND BREADBOARD PERFORMANCE SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB This article summarizes the design concepts and measured performance characteristics of an X-band bread-board deep-space transponder (DST) for future spacecraft applications, with the first use scheduled for the Cassini missions in 1997 and 1996, respectively. The DST consists of a double-conversion, superheterodyne, automatic phase tracking receiver, and an X-band exciter to drive redundant downlink power amplifiers. The receiver acquires and coherently phase tracks the modulated or unmodulated X-band uplink carrier signal. The exciter phase modulates the X-band downlink signal with composite telemetry and ranging signals. The measured tracking threshold, automatic gain control (AGC), static phase error, and phase jitter characteristics of the breadboard DST are in good agreement with the expected performance. The measured results show a receiver tracking threshold of - 158 dBm and a dynamic signal range of 88 dB. RP MYSOOR, NR (reprint author), JET PROP LAB,4800 OAK GR DR,PASADENA,CA 91109, USA. NR 10 TC 4 Z9 5 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1192 EP 1198 DI 10.1109/22.141351 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200019 ER PT J AU KINMAN, PW AF KINMAN, PW TI DOPPLER TRACKING OF PLANETARY SPACECRAFT SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB This article concerns the measurement of Doppler shift on microwave links that connect planetary spacecraft with the Deep Space Network. Such measurements are made by tracking the Doppler effect with phase-locked loop receivers. A description of equipment and techniques as well as a summary of the appropriate mathematical models are given. The two-way Doppler shift is measured by transmitting a highly-stable microwave (uplink) carrier from a ground station, having the spacecraft coherently transpond this carrier, and using a phase-locked loop receiver at the ground station to track the returned (downlink) carrier. The largest sources of measurement error are usually plasma noise and thermal noise. The plasma noise, which may originate in the ionosphere or the solar corona, is discussed; and a technique to partially calibrate its effect, involving the use of two simultaneous downlink carriers that are coherently related, is described. Range measurements employing Doppler rate-aiding are also described. RP KINMAN, PW (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 11 Z9 11 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1199 EP 1204 DI 10.1109/22.141352 PG 6 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200020 ER PT J AU BATHKER, DA VERUTTIPONG, W OTOSHI, TY CRAMER, PW AF BATHKER, DA VERUTTIPONG, W OTOSHI, TY CRAMER, PW TI BEAM-WAVE-GUIDE ANTENNA PERFORMANCE PREDICTIONS WITH COMPARISONS TO EXPERIMENTAL RESULTS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB This article presents an overview of a NASA/JPL antenna project, with specific focus on the methodology used to predict the microwave performance of a new 34-m-diameter beam-waveguide (BWG) reflector antenna, designated DSS 13. Deep Space Station 13 is the research and development facility serving the NASA/JPL Deep Space Network. Three companion articles in this issue detail the microwave test packages, test results, and microwave holography-based evaluations and alignment. This article provides microwave performance predictions as well as a summary of test results for the antenna, which has Cassegrain and centerline BWG operating modes at X-band (8.450-GHz) and Ka-band (32-GHz) frequencies. Predictions were used to identify critical and poorly understood areas needing further study and diagnostic testing, and assisted in planning, scheduling, and evaluating the final results of a detailed test program. Predictions were assembled for all known losses that contribute to antenna performance degradations, including antenna area efficiencies, corresponding beampeak gains, and noise temperatures. It was found that predictions and experimental results agreed reasonably well for beampeak gain and corresponding efficiency, and for several (but not all) noise temperatures. It is believed that the performance predictions and measurements described herein may be the most detailed and accurate available for a large reflector antenna with two significant operating modes and two frequencies. RP BATHKER, DA (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 13 TC 9 Z9 10 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1274 EP 1285 DI 10.1109/22.141361 PG 12 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200029 ER PT J AU OTOSHI, TY STEWART, SR FRANCO, MM AF OTOSHI, TY STEWART, SR FRANCO, MM TI PORTABLE MICROWAVE TEST PACKAGES FOR BEAM-WAVE-GUIDE ANTENNA PERFORMANCE EVALUATIONS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Portable microwave test packages used to evaluate a new 34-m-diameter beam-waveguide (BWG) antenna are described. The experimental methodology involved transporting test packages to different focal points of the BWG system and making noise temperature, antenna efficiency, and holography measurements. Comparisons of data measured at the different focal points enabled determinations of performance degradations caused by various mirrors in the BWG system. It is shown that, due to remarkable stabilities and accuracies of radiometric data obtained through the use of the microwave test packages, degradations caused by the BWG system were successfully determined. C1 PRC INC,ENGN TECHNOL GRP,PASADENA,CA 91107. RP OTOSHI, TY (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1286 EP 1293 DI 10.1109/22.141362 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200030 ER PT J AU ROCHBLATT, DJ SEIDEL, BL AF ROCHBLATT, DJ SEIDEL, BL TI MICROWAVE ANTENNA HOLOGRAPHY SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Microwave holography, as applied to reflector antennas, is a technique with utilizes the Fourier Transform relation between the complex far-field radiation pattern of an antenna and the complex aperture distribution. Resulting aperture phase and amplitude distribution data are used to precisely characterize various crucial performance parameters, including panel alignment, subreflector position, antenna aperture illumination, directivity at various frequencies, and gravity deformation effects. The holography technique provides a methodology for analysis, evaluation, and RF performance improvement of large reflector and beam waveguide antennas. Strong CW signals obtained from geostationary sources were used as far-field sources. This article describes the application of the holography technique to the newly constructed NASA/JPL Deep Space Network (DSN) 34-m beam-waveguide antenna, resulting in 4.1-dB performance improvement at 32 GHz by reducing the main reflector rms surface error to 0.43 mm. The improved antenna performance was verified by additional holographic measurements and efficiency measurements at X-band (8.45 GHz). Microwave holography has been demonstrated to be a required tool for achieving antenna aperture efficiency of 52% at Ka-band (32 GHz), and is likely required for maintaining an operational DSN Ka-band ground antenna capability. RP ROCHBLATT, DJ (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 8 TC 14 Z9 14 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1294 EP 1300 DI 10.1109/22.141363 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200031 ER PT J AU SLOBIN, SD OTOSHI, TY BRITCLIFFE, MJ ALVAREZ, LS STEWART, SR FRANCO, MM AF SLOBIN, SD OTOSHI, TY BRITCLIFFE, MJ ALVAREZ, LS STEWART, SR FRANCO, MM TI EFFICIENCY MEASUREMENT TECHNIQUES FOR CALIBRATION OF A PROTOTYPE 34-METER-DIAMETER BEAM-WAVE-GUIDE ANTENNA AT 8.45 AND 32 GHZ SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Efficiency measurements at 8.45 and 32 GHz (X- and Ka-bands) have been carried out-on a new 34-meter-diameter beam-waveguide antenna now in use at the NASA/JPL Goldstone Deep Space Communications Complex. The use of portable test packages enabled measurements at both the Cassegrain and beam-waveguide focal points. Radio sources (quasars and Venus) were used as calibrators, and updated determinations of flux and source size correction were made during the period of the measurements. Gain and efficiency determinations as a function of elevation angle are presented, and the effects of the beam-waveguide system and antenna structure are clearly seen. At the beam-waveguide focus, an 8.45-GHz peak efficiency of 72.38 percent was measured; at 32 GHz, 44.89 percent was measured. RP SLOBIN, SD (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 11 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD JUN PY 1992 VL 40 IS 6 BP 1301 EP 1309 DI 10.1109/22.141364 PG 9 WC Engineering, Electrical & Electronic SC Engineering GA HZ012 UT WOS:A1992HZ01200032 ER PT J AU BARNES, CE FLEETWOOD, DM SHAW, DC WINOKUR, PS AF BARNES, CE FLEETWOOD, DM SHAW, DC WINOKUR, PS TI POST IRRADIATION EFFECTS (PIE) IN INTEGRATED-CIRCUITS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1ST EUROPEAN CONF ON RADIATION AND ITS EFFECTS ON DEVICES AND SYSTEMS ( RADECS 91 ) CY SEP 09-12, 1991 CL LA GRANDE MOTTE, FRANCE ID SPACE ENVIRONMENTS; HARDNESS ASSURANCE; MOS DEVICES; RADIATION HARDNESS; DOSE-RATE; X-RAY; CMOS; TRANSISTORS; ELECTRONICS; MECHANISMS AB Post Irradiation Effects (PIE) ranging from normal recovery to catastrophic failure have been observed in integrated circuits during the PIE period. These variations indicate that a rebound or PIE "recipe" used for radiation hardness assurance must be chosen with care. In this paper, we provide examples of PIE in a variety of integrated circuits of importance to spacecraft electronics. C1 SANDIA NATL LABS,ALBUQUERQUE,NM 87185. RP BARNES, CE (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 32 TC 8 Z9 8 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1992 VL 39 IS 3 BP 328 EP 341 DI 10.1109/23.277513 PN 1 PG 14 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA JA320 UT WOS:A1992JA32000002 ER PT J AU STASSINOPOULOS, EG BOROWICK, J AF STASSINOPOULOS, EG BOROWICK, J TI CORRELATION OF PROTON AND HEAVY-ION TEST-RESULTS ON CMOS BULK MEMORIES USED FOR SPACE APPLICATIONS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT 1ST EUROPEAN CONF ON RADIATION AND ITS EFFECTS ON DEVICES AND SYSTEMS ( RADECS 91 ) CY SEP 09-12, 1991 CL LA GRANDE MOTTE, FRANCE AB Experiments were performed to determine the heavy-ion and proton sensitivity of CMOS Bulk 2Kx8 RH Space-Qualified SRAMs. The tests were conducted at room temperature and worst-case supply voltage on devices with several different cross-coupled memory cell resistor values. The results indicated correlation between heavy-ion LET threshold versus proton apparent threshold. The heavy-ion data indicate a correlation between the upset cross-sections and resistor values as well. Several proton energies were used to determine energy dependence of proton sensitivity. A special assessment/evaluation of the measured, calculated, and inferred parameter values was performed. The results were used to predict upset rates for a mission-specific space environment. C1 HONEYWELL INC,CTR SOLID STATE ELECTR,PLYMOUTH,MN. RP STASSINOPOULOS, EG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 1 TC 1 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD JUN PY 1992 VL 39 IS 3 BP 450 EP 454 DI 10.1109/23.277536 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA JA320 UT WOS:A1992JA32000025 ER PT J AU BUTLER, RW AF BUTLER, RW TI THE SURE APPROACH TO RELIABILITY-ANALYSIS SO IEEE TRANSACTIONS ON RELIABILITY LA English DT Article DE MARKOV ANALYSIS; FAULT-TOLERANT SYSTEM; MODELING; SEMI-MARKOV ID TOLERANT COMPUTER-SYSTEMS; PREDICTION AB The SURE computer program is a reliability-analysis tool for ultrareliable computer-system architectures. SURE is based on computational methods developed at the NASA Langley Research Center. These methods provide an efficient means for computing reasonably accurate upper and lower bounds for the death state probabilities of a large class of semi-Markov models. Once a semi-Markov model is described using a simple input language, SURE automatically computes the upper and lower bounds on the probability of system failure. A parameter of the model can be specified as a variable over a range of values, thus directing SURE to perform a sensitivity analysis automatically. This feature, along with the speed of the program, makes it an especially useful design tool. SURE is a flexible, user-friendly reliability-analysis tool. The program provides a rapid computational capability for semi-Markov models useful for describing the fault-handling behavior of fault-tolerant computer systems. The only modeling restriction imposed by the program is that the non-exponential recovery transitions must be fast in comparison to the mission time - a desirable attribute of all fault-tolerant systems. The SURE reliability-analysis method uses a fast bounding theorem based on means and variances; the method yields upper and lower bounds on the probability of system failure. The upper and lower bounds are typically within 5 percent of each other. Techniques have been developed to enable SURE to solve models with loops and calculate the operational-state probabilities. The computation is extremely fast, and large state-spaces can be directly solved; a pruning technique enables SURE to process extremely large models. RP BUTLER, RW (reprint author), NASA,LANGLEY RES CTR,MS 130,HAMPTON,VA 23665, USA. NR 23 TC 14 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 SN 0018-9529 J9 IEEE T RELIAB JI IEEE Trans. Reliab. PD JUN PY 1992 VL 41 IS 2 BP 210 EP 218 DI 10.1109/24.257783 PG 9 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA HY359 UT WOS:A1992HY35900013 ER PT J AU WALKER, CK KOOI, JW CHANT, M LEDUC, HG SCHAFFER, PL CARLSTROM, JE PHILLIPS, TG AF WALKER, CK KOOI, JW CHANT, M LEDUC, HG SCHAFFER, PL CARLSTROM, JE PHILLIPS, TG TI A LOW-NOISE 492 GHZ SIS WAVE-GUIDE RECEIVER SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article AB In this paper we discuss the design and performance of an SIS waveguide receiver which provides low noise performance from 375 to 510 GHz. At its design frequency of 492 GHz the receiver has a double sideband noise temperature of approximately 172 K. By using embedded magnetic field concentrators, we are able to effectively suppress Josephson pair tunneling. Techniques for improving receiver performance are discussed. C1 CALTECH,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. NR 11 TC 63 Z9 63 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0195-9271 J9 INT J INFRARED MILLI JI Int. J. Infrared Millimeter Waves PD JUN PY 1992 VL 13 IS 6 BP 785 EP 798 DI 10.1007/BF01011595 PG 14 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA HV819 UT WOS:A1992HV81900001 ER PT J AU BORIC, O TOLMUNEN, TJ KOLLBERG, E FRERKING, MA AF BORIC, O TOLMUNEN, TJ KOLLBERG, E FRERKING, MA TI ANOMALOUS CAPACITANCE OF QUANTUM-WELL DOUBLE BARRIER DIODES SO INTERNATIONAL JOURNAL OF INFRARED AND MILLIMETER WAVES LA English DT Article DE QUANTUM WELL DOUBLE BARRIER DIODES; SCHOTTKY DIODES; S-PARAMETER; IMPEDANCE; CAPACITANCE AB The S-parameters of several different quantum well double barrier diodes have been measured. A technique has been developed for measuring whisker contacted diodes with an HP 8510B automatic network analyzer. Special coaxial mounts using K-connectors were designed to enable measurements up to 20 GHz. The voltage-dependent conductance and capacitance were derived from the measured reflection coefficient of each device. The C/V characteristics were observed to exhibit an anomalous increase at voltages corresponding the the negative differential resistance region (NDR). These are the first reported S-parameter measurements in the negative differential resistance region of quantum well double barrier diodes. A theory is presented that explains, in part, the observed results. C1 CALTECH,DIV ENGN & APPL SCI,PASADENA,CA 91125. JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. CHALMERS UNIV TECHNOL,S-41296 GOTHENBURG,SWEDEN. NR 7 TC 11 Z9 11 U1 0 U2 1 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0195-9271 J9 INT J INFRARED MILLI JI Int. J. Infrared Millimeter Waves PD JUN PY 1992 VL 13 IS 6 BP 799 EP 814 DI 10.1007/BF01011596 PG 16 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA HV819 UT WOS:A1992HV81900002 ER PT J AU DOYCHAK, J AF DOYCHAK, J TI METAL-MATRIX AND INTERMETALLIC-MATRIX COMPOSITES FOR AEROSPACE PROPULSION AND POWER-SYSTEMS SO JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY LA English DT Article ID 1300-K COMPRESSIVE PROPERTIES; HIGH-TEMPERATURE STRENGTH AB Successful development and deployment of metal-matrix composites and intermetallic-matrix composites are critical to reaching the goals of many advanced aerospace propulsion and power development programs. The material requirements are based on the aerospace propulsion and power system requirements, economics, and other factors. Advanced military and civilian aircraft engines will require higher specific strength materials that operate at higher temperatures, and the civilian engines will also require long lifetimes. The specific space propulsion and power applications require high-temperature, high-thermal-conductivity,and high-strength materials. Metal-matrix composites and intermetallic-matrix composites either fulfill or have the potential of fulfilling these requirements. RP DOYCHAK, J (reprint author), NASA,LEWIS RES CTR,DIV MAT,ENABLING PROPULS MAT PROJECT OFF,CLEVELAND,OH 44135, USA. NR 62 TC 42 Z9 42 U1 0 U2 4 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1047-4838 J9 JOM-J MIN MET MAT S JI JOM-J. Miner. Met. Mater. Soc. PD JUN PY 1992 VL 44 IS 6 BP 46 EP 51 PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing SC Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing GA HY415 UT WOS:A1992HY41500013 ER PT J AU KITAMURA, T GHOSN, LJ OHTANI, R AF KITAMURA, T GHOSN, LJ OHTANI, R TI STOCHASTIC MODELING OF CRACK INITIATION AND SHORT-CRACK GROWTH UNDER CREEP AND CREEP-FATIGUE CONDITIONS SO JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME LA English DT Article AB A simplified stochastic model is proposed for crack initiation and short-crack growth under creep and creep-fatigue conditions. Material inhomogeneity provides the random nature of crack initiation and early growth. In the model, the influence of microstructure is introduced by the variability of (1) damage accumulation along grain boundaries, (2) critical damage required for crack initiation or growth, and (3) the grain-boundary length. The probabilities of crack initiation and growth are derived by using convolution integrals. The model is calibrated and used to predict the crack density and crack-growth rate of short cracks of 304 stainless steel under creep and creep-fatigue conditions. The mean crack initiation lives are predicted to be within an average deviation of about ten percent from the experimental results. The predicted cumulative distributions of crack-growth rate follow the experimental data closely. The applicability of the simplified stochastic model is discussed and the future research direction is outlined. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,BROOK PK,OH 44142. RP KITAMURA, T (reprint author), KYOTO UNIV,DEPT ENGN SCI,KYOTO 606,JAPAN. NR 18 TC 0 Z9 0 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0021-8936 J9 J APPL MECH-T ASME JI J. Appl. Mech.-Trans. ASME PD JUN PY 1992 VL 59 IS 2 BP S35 EP S42 DI 10.1115/1.2899505 PN 2 PG 8 WC Mechanics SC Mechanics GA JA699 UT WOS:A1992JA69900006 ER PT J AU RICHMAN, MW OYEDIRAN, AA AF RICHMAN, MW OYEDIRAN, AA TI GRAIN-SIZE REDUCTION IN GRANULAR FLOWS OF SPHERES - THE EFFECTS OF CRITICAL IMPACT ENERGY SO JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME LA English DT Article AB We extend methods employed to derive recent kinetic theories for rapid noncomminuting granular flows, to homogeneous flows in which a fraction of the repeated collisions produce tiny fractures on the particles' peripheries and gradually reduce their effective diameters. The theory consists of balance equations for mass, momentum, and energy, as well as constitutive relations for the pressure tensor and collisional rates of mass and energy lost. We improve upon the work of Richman and Chou (1989) by incorporating into the constitutive theory the critical impact energy below which no mass loss occurs in a binary collision. The theory is applied to granular shear flows and, for fixed shear raf es, predicts the time variations of the solid fraction, granular temperature, and induced stresses, as well as their extreme sensitivities to small changes in the critical impact energy. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,NATL RES COUNCIL,SPACE SCI LAB,FLUID DYNAM BRANCH,HUNTSVILLE,AL 35812. RP RICHMAN, MW (reprint author), WORCESTER POLYTECH INST,HIGGINS LABS,DEPT MECH ENGN,WORCESTER,MA 01609, USA. NR 9 TC 1 Z9 1 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0021-8936 J9 J APPL MECH-T ASME JI J. Appl. Mech.-Trans. ASME PD JUN PY 1992 VL 59 IS 2 BP S17 EP S22 DI 10.1115/1.2899485 PN 2 PG 6 WC Mechanics SC Mechanics GA JA699 UT WOS:A1992JA69900003 ER PT J AU PRABHAKARA, C DALU, G LIBERTI, GL NUCCIARONE, JJ SUHASINI, R AF PRABHAKARA, C DALU, G LIBERTI, GL NUCCIARONE, JJ SUHASINI, R TI RAINFALL ESTIMATION OVER OCEANS FROM SMMR AND SSM/I MICROWAVE DATA SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID ATMOSPHERIC WATER-VAPOR; PRECIPITATING CLOUD; NIMBUS-7 SMMR; CONVECTIVE RAINFALL; RADIATIVE-TRANSFER; LIQUID WATER; WIND-SPEED; EL NINO; SATELLITE; SPACE AB Passive microwave measurements made by the Scanning Multichannel Microwave Radiometer (SMMR) and the Special Sensor Microwave/Imager (SSM/I) reveal information about rain and precipitation-sized ice in the field of view (FOV) of the instruments. The brightness temperature T(b) measured at 37 GHz, having an FOV of about 30 km, shows relatively strong emission from rain and only marginal effects caused by scattering by ice above the rain clouds. At frequencies below 37 GHz, where the FOV is larger and the volume extinction coefficient is weaker, it is found that the observations made by these radiometers do not yield appreciable additional information about rain. At 85 GHz (FOV almost-equal-to 15 km), where the volume extinction coefficient is considerably larger, direct information about rain below the clouds is generally masked. Based on the above considerations, 37-GHz observations with a 30-km FOV from SMMR and SSM/I are selected for the purpose of rain-rate retrieval over oceans. An empirical method is developed to estimate the rain rate in which it is assumed that over an oceanic area the statistics of the observed T(b)'s at 37 GHz in a rain storm are related to the rain-rate statistics in that storm. Also, in this method, the underestimation of rain rate, arising from the inability of the radiometer to respond sensitively to rain rate above a given threshold, is rectified with the aid of two parameters that depend on the total water vapor content in the atmosphere. The rain rates retrieved by this method compare favorably with radar observations. Monthly mean global maps of rain derived from this technique over the oceans are consistent with climatology. C1 CNR,IST FIS ATMOSFERA,ROME,ITALY. ST SYST CORP STX,LANHAM,MD. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP PRABHAKARA, C (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 913,GREENBELT,MD 20771, USA. RI Liberti, Gian Luigi/C-3331-2013; OI Liberti, Gian Luigi/0000-0002-1906-5248; LIBERTI, GIANLUIGI/0000-0003-0091-8607 NR 44 TC 31 Z9 31 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD JUN PY 1992 VL 31 IS 6 BP 532 EP 552 DI 10.1175/1520-0450(1992)031<0532:REOOFS>2.0.CO;2 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HV480 UT WOS:A1992HV48000003 ER PT J AU GAINES, SE BOWEN, SW HIPSKIND, RS BUI, TP CHAN, KR AF GAINES, SE BOWEN, SW HIPSKIND, RS BUI, TP CHAN, KR TI COMPARISONS OF THE NASA ER-2 METEOROLOGICAL MEASUREMENT SYSTEM WITH RADAR TRACKING AND RADIOSONDE DATA SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article AB Measurements of aircraft longitude. latitude, and velocity, and measurements of atmospheric pressure, temperature, and horizontal wind from the meteorological measurement system (MMS) on board the NASA ER-2 aircraft were compared with independent measurements of these quantities from radiosondes and radar tracking of both the ER-2 and radiosonde balloons. In general, the comparisons were good and within the expected measurement accuracy and natural variability of the meteorological parameters. Radar tracking of the ER-2 resolved the velocity and position drift of the inertial navigation system (INS). The rms errors in the horizontal velocity components of the ER-2, due to INS errors, were found to be 0.5 m s-1. The magnitude of the drift in longitude and latitude depends on the sign and magnitude of the corresponding component velocity drift and can be a few hundredths of a degree. The radar altitudes of the ER-2 and radiosondes were used as the basis for comparing measurements of atmospheric pressure, temperature, and horizontal wind from these two platforms. The uncertainty in the MMS horizontal wind measurement is estimated to be +/- 2.5 m s-1. The accuracy of the MMS pressure and temperature measurements were inferred to be +/- 0.3 hPa and +/- 0.3 K. RP GAINES, SE (reprint author), NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 0 TC 8 Z9 8 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD JUN PY 1992 VL 9 IS 3 BP 210 EP 225 DI 10.1175/1520-0426(1992)009<0210:COTNEM>2.0.CO;2 PG 16 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA HU232 UT WOS:A1992HU23200002 ER PT J AU SCHLEGEL, K PFAFF, RF AF SCHLEGEL, K PFAFF, RF TI E-REGION IRREGULARITIES - A SELECTION OF PAPERS PRESENTED AT THE XXIII URSI GENERAL-ASSEMBLY HELD IN PRAGUE, CZECHOSLOVAKIA, AUGUST 1990 SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Editorial Material C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP SCHLEGEL, K (reprint author), MAX PLANCK INST AERON,LINDAU,GERMANY. RI Pfaff, Robert/F-5703-2012 OI Pfaff, Robert/0000-0002-4881-9715 NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD JUN PY 1992 VL 54 IS 6 BP 655 EP 655 DI 10.1016/0021-9169(92)90103-R PG 1 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JA460 UT WOS:A1992JA46000001 ER PT J AU PFAFF, RF SAHR, J PROVIDAKES, JF SWARTZ, WE FARLEY, DT KINTNER, PM HAGGSTROM, I HEDBERG, A OPGENOORTH, H HOLMGREN, G MCNAMARA, A WALLIS, D WHALEN, B YAU, A WATANABE, S CREUTZBERG, F WILLIAMS, P NIELSEN, E SCHLEGEL, K ROBINSON, TR AF PFAFF, RF SAHR, J PROVIDAKES, JF SWARTZ, WE FARLEY, DT KINTNER, PM HAGGSTROM, I HEDBERG, A OPGENOORTH, H HOLMGREN, G MCNAMARA, A WALLIS, D WHALEN, B YAU, A WATANABE, S CREUTZBERG, F WILLIAMS, P NIELSEN, E SCHLEGEL, K ROBINSON, TR TI THE E-REGION ROCKET RADAR INSTABILITY STUDY (ERRRIS) - SCIENTIFIC OBJECTIVES AND CAMPAIGN OVERVIEW SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT WORKSHOP ON COMBINED ROCKET AND RADAR STUDIES OF E-REGION PLASMA INSTABILITIES, AT THE 23RD URSI GENERAL ASSEMBLY CY AUG, 1990 CL PRAGUE, CZECHOSLOVAKIA ID AURORAL E-REGION; ION-CYCLOTRON WAVES; NON-LINEAR THEORY; PLASMA-WAVES; INTERFEROMETER OBSERVATIONS; EQUATORIAL ELECTROJET; 2-STREAM INSTABILITY; IRREGULARITIES; ARC; VELOCITY AB The E-region Rocket/Radar Instability Study (Project ERRRIS) investigated in detail the plasma instabilities in the low altitude (E-region) auroral ionosphere and the sources of free energy that drive these waves. Three independent sets of experiments were launched on NASA sounding rockets from Esrange, Sweden, in 1988 and 1989, attaining apogees of 124, 129 and 176 km. The lower apogee rockets were flown into the unstable auroral electrojet and encountered intense two-stream waves driven by d.c. electric fields that ranged from 35 to 115 mV/m. The higher apogee rocket returned fields and particle data from an active auroral arc, yet observed a remarkably quiescent electrojet region as the weak d.c. electric fields (approximately 10-15 mV/m) there were below the threshold required to excite two-stream waves. The rocket instrumentation included electric field instruments (d.c. and wave), plasma density fluctuation (delta-n/n) receivers, d.c. fluxgate magnetometers, energetic particle detectors (ions and electrons), ion drift meters, and swept Langmuir probes to determine absolute plasma density and temperature. The wave experiments included spatially separated sensors to provide wave vector and phase velocity information. All three rockets were flown in conjunction with radar backscatter measurements taken by the 50 MHz CUPRI system, which was the primary tool used to determine the launch conditions. Two of the rockets were flown in conjunction with plasma drift, density, and temperature measurements taken by the EISCAT incoherent scattar radar. The STARE radar also made measurements during this campaign. This paper describes the scientific objectives of these rocket/radar experiments, provides a summary of the geophysical conditions during each launch, and gives an overview of the principal rocket and radar observations. C1 CORNELL UNIV,ITHACA,NY 14853. SWEDISH INST SPACE PHYS,KIRUNA,SWEDEN. HERZBERG INST ASTROPHYS,OTTAWA,ONTARIO,CANADA. UNIV ABERYSTWYTH,ABERYSTWYTH,WALES. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. UNIV LEICESTER,LEICESTER LE1 7RH,ENGLAND. RP PFAFF, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20071, USA. RI Watanabe, Shigeto/A-4305-2012; Pfaff, Robert/F-5703-2012; Yau, Andrew/E-7007-2013; OI Pfaff, Robert/0000-0002-4881-9715; Yau, Andrew/0000-0002-8210-0392; Haggstrom, Ingemar/0000-0003-1070-6915 NR 35 TC 21 Z9 21 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD JUN PY 1992 VL 54 IS 6 BP 779 EP 808 DI 10.1016/0021-9169(92)90116-3 PG 30 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JA460 UT WOS:A1992JA46000014 ER PT J AU SAHR, JD FARLEY, DT SWARTZ, WE PROVIDAKES, JF PFAFF, RF AF SAHR, JD FARLEY, DT SWARTZ, WE PROVIDAKES, JF PFAFF, RF TI OBSERVATIONS OF 3-M AURORAL IRREGULARITIES DURING THE ERRRIS CAMPAIGNS SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT WORKSHOP ON COMBINED ROCKET AND RADAR STUDIES OF E-REGION PLASMA INSTABILITIES, AT THE 23RD URSI GENERAL ASSEMBLY CY AUG, 1990 CL PRAGUE, CZECHOSLOVAKIA ID RADAR INTERFEROMETER OBSERVATIONS; EQUATORIAL ELECTROJET; E-REGION AB In the late winter of 1988 and 1989, three NASA sounding rockets were flown through the auroral electrojet from ESRANGE (Sweden) as part of the E-region Rocket--Radar Instability Study (ERRIS). Many ground-based instruments supported these flights. including the EISCAT, STARE, and CUPRI radars, as well as all-sky cameras, riometers, and magnetometers. In this paper we summarize the observations of the Cornell University Portable Radar Interferometer (CUPRI), which detected coherent backscatter from 3-m irregularities in the auroral E-region. Twenty hours of power spectra and interferometry data are available, and, during the 1989 campaign, three weeks of nearly continuous Range-Time-Intensity (RTI) and first moment data were recorded. C1 MITRE CORP,BEDFORD,MA 01730. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP SAHR, JD (reprint author), CORNELL UNIV,SCH ELECT ENGN,ITHACA,NY 14853, USA. RI Pfaff, Robert/F-5703-2012 OI Pfaff, Robert/0000-0002-4881-9715 NR 13 TC 6 Z9 6 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD JUN PY 1992 VL 54 IS 6 BP 809 EP 818 DI 10.1016/0021-9169(92)90117-4 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA JA460 UT WOS:A1992JA46000015 ER PT J AU MALUENDES, S MCLEAN, AD GREEN, S AF MALUENDES, S MCLEAN, AD GREEN, S TI COMMENT ON BROADENING OF WATER MICROWAVE LINES BY COLLISIONS WITH HELIUM-ATOMS SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID EXCITATION; SCATTERING; TRANSITION; MOLECULES; H2O AB Earlier theoretical descriptions of interaction forces and collision dynamics in the H2O-He system [A. Palma et al., J. Chem. Phys. 89, 1401 (1988); S. Green et al., ibid. 94, 1346 (1991)] are improved by calculating the interaction at additional orientations and by including diffuse functions in the molecular orbital expansion basis set. The improvements make substantial changes to the potential energy surface, but make only small changes in predicted microwave pressure broadening coefficients. The qualitative temperature dependence and relative widths of different lines appear to be converged with respect to successive improvements to the theoretical description of this system. Remaining discrepancies with available data must reflect problems with the experimental values. C1 IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP MALUENDES, S (reprint author), MOLEC RES INST,PALO ALTO,CA 94304, USA. NR 17 TC 24 Z9 24 U1 0 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUN 1 PY 1992 VL 96 IS 11 BP 8150 EP 8156 DI 10.1063/1.462318 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA HW836 UT WOS:A1992HW83600030 ER PT J AU SHEN, TC AF SHEN, TC TI INSITU POLYMERIZATION PLOT COLUMNS .1. DIVINYLBENZENE SO JOURNAL OF CHROMATOGRAPHIC SCIENCE LA English DT Article RP SHEN, TC (reprint author), SETI INST,AMES RES CTR,MS-239-12,MOFFETT FIELD,CA 94035, USA. NR 13 TC 14 Z9 14 U1 3 U2 5 PU PRESTON PUBLICATIONS INC PI NILES PA 7800 MERRIMAC AVE PO BOX 48312, NILES, IL 60648 SN 0021-9665 J9 J CHROMATOGR SCI JI J. Chromatogr. Sci. PD JUN PY 1992 VL 30 IS 6 BP 239 EP 240 PG 2 WC Biochemical Research Methods; Chemistry, Analytical SC Biochemistry & Molecular Biology; Chemistry GA HY004 UT WOS:A1992HY00400006 PM 11540239 ER PT J AU NAIK, RA CREWS, JH AF NAIK, RA CREWS, JH TI FRACTURE-MECHANICS ANALYSIS FOR VARIOUS FIBER/MATRIX INTERFACE LOADINGS SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE COMPOSITES; INTERFACE; STRESS INTENSITY FACTORS; FRACTURE; FINITE ELEMENT ANALYSIS ID STRESS INTENSITY FACTORS; CRACK AB Fiber/matrix (F/M) cracking was analyzed to provide better understanding and guidance in developing F/M interface fracture toughness tests. Two configurations, corresponding to F/M cracking at a broken fiber and at the free edge, were investigated. The effects of mechanical loading, thermal cooldown, and friction were investigated. Each configuration was analyzed for two loadings: longitudinal and normal to the fiber. A nonlinear finite element analysis was performed to model friction and slip at the F/M interface. A procedure for fitting a square-root singularity to calculated stresses was used to determine stress intensity factors (K(I) and K(II)) for a bimaterial interface crack. For the case of F/M cracking at a broken fiber with longitudinal loading, crack tip conditions were strongly influenced by interface friction. As a result, a F/M interface toughness test based on this case was not recommended because nonlinear data analysis methods would be required to calculate frictional energy. For the free edge crack configuration, both mechanical and thermal loading caused crack opening, thereby avoiding frictional effects. A F/M interface toughness test based on this configuration would provide data for K(I)/K(II) ratios of about 0.7 and 1.6 for fiber and radial normal loading, respectively. However, thermal effects must be accounted for in the data analysis. C1 NASA,LANGLEY RES CTR,ANALYT SERV & MAT INC,HAMPTON,VA 23665. NR 15 TC 0 Z9 0 U1 1 U2 1 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD SUM PY 1992 VL 14 IS 2 BP 80 EP 85 PG 6 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA JY516 UT WOS:A1992JY51600003 ER PT J AU OBRIEN, TK AF OBRIEN, TK TI RESIDUAL THERMAL AND MOISTURE INFLUENCES ON THE ANALYSIS OF LOCAL DELAMINATIONS SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE RESIDUAL THERMAL STRESS; HYGROSCOPIC STRESS; MOISTURE; STRAIN ENERGY RELEASE RATE; DELAMINATION; MATRIX CRACK AB An analysis using laminated plate theory is developed to calculate the strain energy release rate associated with local delaminations originating at off-axis, angle-ply, matrix cracks in laminates subjected to uniaxial loads. The analysis includes the contribution of residual thermal and moisture stresses to the strain energy released. Examples are calculated for the strain energy release rate associated with local delaminations originating at 90-degrees and angle-ply (non 90-degrees) matrix-ply cracks in glass-epoxy and graphite-epoxy laminates. The solution developed may be used to assess the relative contribution of mechanical, residual thermal, and moisture stresses on the strain energy release rate for local delamination for a variety of layups and materials. C1 USA,NASA,LANGLEY RES CTR,AEROSTRUCT DIRECTORATE,HAMPTON,VA 23665. NR 11 TC 3 Z9 3 U1 0 U2 0 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD SUM PY 1992 VL 14 IS 2 BP 86 EP 94 PG 9 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA JY516 UT WOS:A1992JY51600004 ER PT J AU SHU, CW AF SHU, CW TI A NUMERICAL-METHOD FOR SYSTEMS OF CONSERVATION-LAWS OF MIXED TYPE ADMITTING HYPERBOLIC FLUX SPLITTING SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Note ID SHOCK-CAPTURING SCHEMES; EFFICIENT IMPLEMENTATION; PHASE BOUNDARIES; RIEMANN PROBLEM; 3-PHASE FLOW C1 NASA, LANGLEY RES CTR, ICASE, HAMPTON, VA 23665 USA. RP BROWN UNIV, DIV APPL MATH, PROVIDENCE, RI 02912 USA. RI Shu, Chi-Wang/A-3216-2013 OI Shu, Chi-Wang/0000-0001-7720-9564 NR 23 TC 18 Z9 19 U1 0 U2 1 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 EI 1090-2716 J9 J COMPUT PHYS JI J. Comput. Phys. PD JUN PY 1992 VL 100 IS 2 BP 424 EP 429 DI 10.1016/0021-9991(92)90249-X PG 6 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JB297 UT WOS:A1992JB29700021 ER PT J AU DEISSLER, RG MOLLS, FB AF DEISSLER, RG MOLLS, FB TI EFFECT OF SPATIAL-RESOLUTION ON APPARENT SENSITIVITY TO INITIAL CONDITIONS OF A DECAYING FLOW AS IT BECOMES TURBULENT SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Note RP DEISSLER, RG (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD JUN PY 1992 VL 100 IS 2 BP 430 EP 432 DI 10.1016/0021-9991(92)90250-3 PG 3 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA JB297 UT WOS:A1992JB29700022 ER PT J AU STONER, BR GLASS, JT BERGMAN, L NEMANICH, RJ ZOLTAL, LD VANDERSANDE, JW AF STONER, BR GLASS, JT BERGMAN, L NEMANICH, RJ ZOLTAL, LD VANDERSANDE, JW TI ELECTRICAL-CONDUCTIVITY AND PHOTOLUMINESCENCE OF DIAMOND FILMS GROWN BY DOWNSTREAM MICROWAVE PLASMA CVD SO JOURNAL OF ELECTRONIC MATERIALS LA English DT Article DE DIAMOND; ELECTRICAL CONDUCTIVITY; PHOTOLUMINESCENCE ID HYDROGEN AB Electrical conductivity measurements and photoluminescence (PL) were used to study the effects that sample distance from the plasma during growth has on the carrier transport properties of undoped CVD diamond. The films were grown by downstream microwave plasma chemical vapor deposition at distances from 0.5 to 2.0 cm from the edge of plasma glow. Electrical conductivity measurements were performed between room temperature and 1000-degrees-C and then complimented with Raman spectroscopy and PL studies in an attempt to gain a better understanding of the CVD growth process and the resulting electrical and optical properties of the diamond films. Room temperature electrical conductivity was found to vary by over 5 orders of magnitude with increasing growth distance from the plasma, while only moderate changes were observed in the luminescence spectra. C1 N CAROLINA STATE UNIV,DEPT PHYS,RALEIGH,NC 27695. JET PROP LAB,PASADENA,CA 91109. RP STONER, BR (reprint author), N CAROLINA STATE UNIV,DEPT MAT SCI & ENGN,RALEIGH,NC 27695, USA. RI Stoner, Brian/D-9747-2011; Glass, Jeffrey/A-2266-2010 OI Glass, Jeffrey/0000-0002-9554-4398 NR 15 TC 13 Z9 13 U1 0 U2 1 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0361-5235 J9 J ELECTRON MATER JI J. Electron. Mater. PD JUN PY 1992 VL 21 IS 6 BP 629 EP 634 DI 10.1007/BF02655431 PG 6 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA HZ504 UT WOS:A1992HZ50400011 ER PT J AU OTTO, SR AF OTTO, SR TI ON STABILITY OF THE FLOW AROUND AN OSCILLATING SPHERE SO JOURNAL OF FLUID MECHANICS LA English DT Article ID BOUNDARY-LAYER; VORTICES; CYLINDER AB The stability of the flow resulting from the oscillations of a sphere in a viscous fluid is investigated. The calculation for the transverse oscillations of the sphere is performed in a linear regime and the result in the weakly nonlinear regime is described; the stability in the case of torsional oscillations is considered in the linear regime, where we take torsional oscillations to mean oscillations about a fixed axis through the centre of the sphere. In both cases we assume that the frequency of the oscillations is large, so that the unsteady boundary layer that results is thin. In the transverse case, the linear stability problem depends only on the radial variable and time. Employing Floquet theory we may reduce the system to a coupled infinite system of ordinary differential equations, with homogeneous boundary conditions, the eigenvalues of this system being found numerically. In the torsional case, the linear stability problem again depends only on the radial variable and time, although the angular variation is retained in a parametric form and is determined at higher order. A WKBJ perturbation solution is constructed and the evolution of the amplitude of the vortex is found. The solution is determined by finding a saddle point in the complex plane of the angular coordinate, and thus the critical Taylor number is derived. C1 UNIV EXETER,DEPT MATH,EXETER EX4 9QE,ENGLAND. RP OTTO, SR (reprint author), NASA,LANGLEY RES CTR,ICASE,MAILSTOP 132C,HAMPTON,VA 23665, USA. NR 17 TC 9 Z9 9 U1 1 U2 1 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUN PY 1992 VL 239 BP 47 EP 63 DI 10.1017/S0022112092004312 PG 17 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JB432 UT WOS:A1992JB43200003 ER PT J AU BELL, JH MEHTA, RD AF BELL, JH MEHTA, RD TI MEASUREMENTS OF THE STREAMWISE VORTICAL STRUCTURES IN A PLANE MIXING LAYER SO JOURNAL OF FLUID MECHANICS LA English DT Article ID FREE SHEAR-LAYER; TURBULENT-FLOW; DETERMINISTIC MODELS; BOUNDARY-LAYER; VORTEX; INSTABILITY; EVOLUTION; DYNAMICS; MOTION; ORIGIN AB An experimental study has been conducted to investigate the three-dimensional structure of a plane, two-stream mixing layer through direct measurements. A secondary streamwise vortex structure has been shown to ride among the primary spanwise vortices in past flow visualization investigations. The main objective of the present study was to establish quantitatively the presence and role of the streamwise vortex structure in the development of a plane turbulent mixing layer at relatively high Reynolds numbers (Re(delta) approximately 2.9 x 10(4)). A two-stream mixing layer with a velocity ratio, U2/U1 = 0.6 was generated with the initial boundary layers laminar and nominally two-dimensional. Mean flow and turbulence measurements were made on fine cross-plane grids across the mixing layer at several streamwise locations with a single rotatable cross-wire probe. The results indicate that the instability, leading to the formation of streamwise vortices, is initially amplified just downstream of the first spanwise roll-up. The streamwise vortices first appear in clusters containing vorticity of both signs. Further downstream, the vortices re-align to form counter-rotating pairs, although there is a relatively large variation in the scale and strengths of the individual vortices. The streamwise vortex spacing increases in a step-wise fashion, at least partially through the amalgamation of like-sign vortices. For the flow conditions investigated, the wavelength associated with the streamwise vortices scales with the mixing-layer vorticity thickness. while their mean strength decays as approximately 1/X1.5. In the near field, the streamwise vortices grossly distort the mean velocity and turbulence distributions within the mixing layer. In particular. the streamwise vorticity is found to be strongly correlated in position, strength and scale with the secondary shear stress (u'w'BAR). The secondary shear stress data suggest that the streamwise structures persist through to what would normally be considered the self-similar region, although they are very weak by this point and the mixing layer otherwise appears to be two-dimensional. C1 STANFORD UNIV, JIAA, DEPT AERONAUT & ASTRONAUT, STANFORD, CA 94305 USA. RP BELL, JH (reprint author), NASA, AMES RES CTR, FLUID MECH LAB, FLUID DYNAM RES BRANCH, MAIL STOP 260-1, MOFFETT FIELD, CA 94035 USA. NR 56 TC 57 Z9 57 U1 0 U2 5 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 EI 1469-7645 J9 J FLUID MECH JI J. Fluid Mech. PD JUN PY 1992 VL 239 BP 213 EP 248 DI 10.1017/S0022112092004385 PG 36 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JB432 UT WOS:A1992JB43200010 ER PT J AU LUNDGREN, TS YAO, J MANSOUR, NN AF LUNDGREN, TS YAO, J MANSOUR, NN TI MICROBURST MODELING AND SCALING SO JOURNAL OF FLUID MECHANICS LA English DT Article ID KELVIN-HELMHOLTZ INSTABILITY; VORTEX SHEET; DYNAMICS; SIMULATIONS; DOWNBURST; RINGS; WALL AB A microburst can be modelled by releasing a volume of fluid that is slightly heavier than the ambient fluid, allowing it to fall onto a horizontal surface. Vorticity develops on the sides of this parcel as it descends and causes it to roll up into a turbulent vortex ring which impinges on the ground. Such a model exhibits many of the features of naturally occurring microbursts which are a hazard to aviation. In this paper this model is achieved experimentally by releasing a volume of salt water into fresh water from a cylindrical dispenser. When care is taken with the release the spreading rate of the surface outflow is measurable and quite repeatable despite the fact that the flow is turbulent. An elementary numerical approximation to this model, based on inviscid vortex dynamics, has also been developed. A scaling law is proposed which allows experiments with different fluid densities to be compared with each other and with the numerical results. More importantly the scaling law allows us to compare the model results with real microbursts. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP LUNDGREN, TS (reprint author), UNIV MINNESOTA,DEPT AEROSP ENGN & MECH,MINNEAPOLIS,MN 55455, USA. NR 26 TC 55 Z9 57 U1 1 U2 9 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUN PY 1992 VL 239 BP 461 EP 488 DI 10.1017/S002211209200449X PG 28 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA JB432 UT WOS:A1992JB43200021 ER PT J AU PEDERSEN, BM AUBIER, MG DESCH, MD AF PEDERSEN, BM AUBIER, MG DESCH, MD TI SCINTILLATIONS OF THE URANIAN KILOMETRIC RADIATION - IMPLICATIONS FOR THE DOWNSTREAM MAGNETOPAUSE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RADIO-EMISSION; SURFACE-WAVES; URANUS; POLARIZATION AB From January 27 to 30, 1986, while Vovager 2 was outbound from Uranus, the planetary radio astronomy experiment recorded strong (approximately 3-6 dB) modulations of the broadband smooth Uranian radio emission (Warwick et al., 1987 a) at frequencies below 500 kHz. These fluctuations exhibited simultaneously two different time scales (approximately 100 s and approximately 10 s) and were exclusively observed outside the Uranian magnetopause during six planetary rotations. The modulations were only present during a part of the total duration of each broadband smooth episode. This phenomenon is interpreted as being due to propagation effects through the magnetopause. The long-period modulation is due to the influence of approximately 8000-km wavelength surface waves on Uranus' downstream magnetopause. Such waves have only been studied in detail for the inbound passage (Lepping et al., 1987). The short-period oscillation might be the signature of a second magnetopause ripple period, similar to that measured by Aubry et al. (1971) for the Earth's magnetopause. There is strong evidence that the surface wave fluctuations causing the scintillations are induced by the solar wind interaction with the magnetosphere. We discuss why these modulations are confined to certain periods of time and to a certain frequency range. C1 UNIV PARIS 06,PARIS,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP PEDERSEN, BM (reprint author), OBSERV PARIS,CNRS,URA 324,DASOP,PLACE JULES JANSSEN,F-92195 MEUDON,FRANCE. NR 23 TC 2 Z9 2 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1992 VL 97 IS A6 BP 8127 EP 8133 DI 10.1029/92JA00307 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX984 UT WOS:A1992HX98400001 ER PT J AU LEPPING, RP BURLAGA, LF LAZARUS, AJ VASYLIUNAS, VM SZABO, A STEINBERG, J NESS, NF KRIMIGIS, SM AF LEPPING, RP BURLAGA, LF LAZARUS, AJ VASYLIUNAS, VM SZABO, A STEINBERG, J NESS, NF KRIMIGIS, SM TI NEPTUNE POLAR CUSP REGION - OBSERVATIONS AND MAGNETIC-FIELD ANALYSIS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SURFACE-WAVES; MAGNETOPAUSE; PLASMA; MAGNETOMETER; VOYAGER-1 AB Upon entering Neptune's magnetosphere, Voyager 2 penetrated its distant polar cusp on August 24, 1989. At that time the planet's magnetic dipole axis was approximately parallel to the Sun-planet line. Broadly speaking, the spacecraft on the day before closest approach traversed four plasma regions. These (and the "boundaries" separating them) are (1) solar wind (bow shock at 1438 UT), (2) magnetosheath (inner boundary of the magnetosheath, the magnetopause (MP), at 1800 UT), (3) cusp region (outer boundary of magnetosphere at 1930 UT), and (4) the magnetosphere. The MP is identified primarily by a 45-degrees directional discontinuity in the magnetic field but also by a decrease in the flux of antisunward flowing plasma, and a change in flow direction toward the corotation direction: it is approximately where the global MP would be expected based on upstream conditions. It is shown that the MP boundary was a rotational discontinuity whose normal n(MP) was a severe almost-equal-to 77-degrees from the planet-Sun line. Its thickness was 5.1 X 10(4) km (i.e., 24 proton gyroradii, consistent with MPs of the other magnetic planets). The boundary was moving at U = 148 km/s, relative to the Sun-planet line, along n(MP), in a sense opposite to the approximate rigid motion of the outer magnetosphere and being dominated by the speed of an Alfven wave moving into the magnetosphere. Plasma-beta-drops from 1.21 to 0.73 across the MP, going from outside to inside. Total pressure balance was shown to exist across the boundary, and the normal momentum flux change was apparently balanced by forces related to the change in thermal anisotropy and the normal field according to MHD theory. Energetic (greater than or similar to 28 keV) ion intensities peaked at almost-equal-to 1800 UT and then decreased prior to a second onset at almost-equal-to 2000 UT, while the electrons (greater than or similar to 22 keV) showed only a marginal increase. The field in the cusp changed direction slowly and smoothly, approaching the magnetospheric field direction at its inner boundary. The plasma velocity and density changed very moderately as the spacecraft entered the cusp region. However, the quasi-steadiness of these quantities in the sheath (on average) disappears as the cusp is entered, just as was true of the magnetic field. Similar magnetic field and plasma profiles in the vicinity of the Earth's distant polar cusp have been observed by Earth orbiting spacecraft. C1 MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20707. UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. RP LEPPING, RP (reprint author), NASA GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20723, USA. NR 22 TC 9 Z9 9 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1992 VL 97 IS A6 BP 8135 EP 8144 DI 10.1029/92JA00314 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX984 UT WOS:A1992HX98400002 ER PT J AU FLAMMER, K BIRMINGHAM, TE MENDIS, DA NORTHROP, TG AF FLAMMER, K BIRMINGHAM, TE MENDIS, DA NORTHROP, TG TI A SELF-CONSISTENT MODEL FOR THE PARTICLES AND FIELDS UPSTREAM OF AN OUTGASSING COMET .2. A TIME-DEPENDENT DESCRIPTION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; IONS; DISTRIBUTIONS; TURBULENCE; PICKUP AB In a previous paper [Flammer et al., 1991], we determined the global variation of the magnetic field and solar wind flow parameters in the unshocked region upstream of an outgassing comet using a kinetic treatment for the cometary ions. Two different assumptions were made concerning the cometary ion distribution function: the pickup cometary ions formed either a velocity space gyrotropic ring distribution or a velocity space isotropic shell distribution in the solar wind frame of reference. In the present paper we consider the general case wherein the newly picked up ions are elastically pitch angle scattered from the initial ring distribution to a shell with some characteristic time scale-tau. Using theoretically determined parameters which reflect the conditions expected at comet Kopff (a typical short-period comet and a possible target for the CRAF/Cassini mission) for various heliocentric distances, we determine how the pitch angle scattering rate affects the global morphology. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,GREENBELT,MD 20771. RP FLAMMER, K (reprint author), UNIV CALIF SAN DIEGO,DEPT ELECT & COMP ENGN,LA JOLLA,CA 92093, USA. NR 18 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1992 VL 97 IS A6 BP 8173 EP 8181 DI 10.1029/92JA00145 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX984 UT WOS:A1992HX98400006 ER PT J AU HORWITZ, JL POLLOCK, CJ MOORE, TE PETERSON, WK BURCH, JL WINNINGHAM, JD CRAVEN, JD FRANK, LA PERSOON, A AF HORWITZ, JL POLLOCK, CJ MOORE, TE PETERSON, WK BURCH, JL WINNINGHAM, JD CRAVEN, JD FRANK, LA PERSOON, A TI THE POLAR-CAP ENVIRONMENT OF OUTFLOWING O+ SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CLEFT ION FOUNTAIN; THETA-AURORA; MAGNETOSPHERE; PLASMA; SPECTROMETER; IONOSPHERE; DENSITIES AB lon composition measurements by Dynamics Explorer 1 often show upward O+ beams at polar latitudes, with streaming energies of 1-20 eV or more. Here we utilize measurements of core (0-50 eV) and "energetic" (approximately 0-1 keV) ion composition, plasma waves, and auroral images from DE 1 and plasma ions and electrons from DE 2 to examine some of their properties in the context of the polar cap environment. It is found that two distinct populations of O+ beams are observed: "high-speed" (10-30 eV or higher streaming energies) and "low-speed" (generally <10-eV streaming energies). The "high-speed" polar beams show an "auroral" connection; i.e., they are observed on or near field lines threading auroral arcs seen in DE 1 images. The "low-speed" streams are on or near field lines threading the dark polar cap and may be convected from the cleft ion fountain. The low-speed streams are generally much more stable in energy and flux, while the high-speed streams tend to be bursty. In general, the streams are convecting antisunward, with velocities of 5-14 km/s in the orbital plane. We sought to obtain plasma density estimates from plasma wave measurements, through analysis of features of auroral hiss as well as upper hybrid emissions. Densities in the range 1-5 el/cm3 were indicated for one segment of a DE 1 polar cap pass; however, the measurements generally indicate little auroral hiss or upper hybrid emissions in the polar cap for the other cases considered here. Estimates of electrostatic potential drops above thc DE 2 satellite have been made using energy-angle spectrograms of photoelectron data, under the assumption that the field lines of observation are "effectively" open. Potential drops often are in the 20- to 40-V range. At other times the potential falls below the approximately 5-V instrument threshold, or there are insufficient photoelectron fluxes for estimation. These limited data suggest that the largest potential drops are just poleward of the cleft or near its poleward edge and there is a decline of the drop in the antisunward direction. No obvious correlation between the potential estimates and "nearby" O+ streaming energies is seen. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. SW RES INST,SAN ANTONIO,TX 78284. RP HORWITZ, JL (reprint author), UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899, USA. RI Moore, Thomas/D-4675-2012; Peterson, WK/A-8706-2009 OI Moore, Thomas/0000-0002-3150-1137; Peterson, WK/0000-0002-1513-6096 NR 27 TC 21 Z9 21 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1992 VL 97 IS A6 BP 8361 EP 8379 DI 10.1029/92JA00147 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX984 UT WOS:A1992HX98400023 ER PT J AU HO, CW HORWITZ, JL SINGH, N WILSON, GR MOORE, TE AF HO, CW HORWITZ, JL SINGH, N WILSON, GR MOORE, TE TI EFFECTS OF MAGNETOSPHERIC ELECTRONS ON POLAR PLASMA OUTFLOW - A SEMIKINETIC MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ION-EXOSPHERE; KINETIC-MODEL; FIELD; WIND; IONOSPHERE; PARALLEL; FLOW AB A semikinetic model for the study of the effect of hot magnetospheric electrons on polar plasma outflow adiabatic, parallel-drifting gyro-centers injected as the upgoing portions of drifting bi-Maxwellian distributions at 1.6 R(E), while the electrons am treated as a massless neutralizing fluid. As a first approach to understanding the effects of hot magnetospheric electrons on the outflow, we consider electron temperature profiles which increase from low temperatures at the ionospheric levels to high temperatures at high altitudes. The electric field is determined by both the electron temperature and its gradient. The electric field produced by the electron temperature alone generally accelerates ions outward while that associated with the electron temperature gradient increases the potential barrier and inhibits the outflow. For typical polar wind stream conditions, electron temperature gradients exceeding 3 x 10(4) K/R(E) cause reflection of much of the ion stream back downward toward the ionosphere. Under these circumstances the H+ outflow forms two counterstreaming beams at altitudes below the reflecting potential barrier and a cooler and faster transmitted beam at high altitudes. Above the potential barrier, the O+ density decreases by 7 orders of magnitude for a very large electron temperature gradient. For the case of an electron temperature profile established by thermal conduction the results show inhibition of polar plasma outflow very near the lower boundary, but continuous acceleration of the escaping ions along most of the flux tube. H+ shows a continuous decrease in net outward flux from 3 x 10(7) ions cm-2 s-1 when the electron temperature is isothermal at 4400 K to 1.5 x 10(7) ions cm-2 s-1 when the upper boundary temperature is increased to 1 x 10(6) K. On the other hand, the flux of O+ exhibits a rise and fall with upper boundary electron temperature with a peak of 1.1 x 10(7) e ions cm-2 s-1 when the upper boundary electron temperature is approximately equal to 2 x 10(5) K. C1 UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP HO, CW (reprint author), UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 30 TC 31 Z9 31 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1992 VL 97 IS A6 BP 8425 EP 8437 DI 10.1029/91JA03158 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX984 UT WOS:A1992HX98400027 ER PT J AU FUNG, SF HOFFMAN, RA AF FUNG, SF HOFFMAN, RA TI FINITE GEOMETRY-EFFECTS OF FIELD-ALIGNED CURRENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID BIRKELAND CURRENTS; MAGNETOPAUSE; TRIAD; DE-1 AB Traditionally, field-aligned current densities calculated from gradients in the perturbation magnetic field measured from low-altitude spacecraft have been based on the assumption that the current regions are infinite in length. However, many measurements clearly indicate that this assumption is invalid. We have performed model calculations of the magnetic field produced by finite current regions that would be measured by a spacecraft-borne magnetometer. These calculations serve two purposes: (1) to assess the extent to which an infinite current sheet approximation is applicable in calculating field-aligned cur-rent densities by comparing the current density computed from the model perturbation magnetic field assuming an infinite length current region to the model current density; and (2) to assist in the interpretation of the magnetometer signals when the infinite sheet current approximation is clearly inapplicable. For current regions with various aspect (length to width) ratios, we find that the perturbation magnetic fields within the current region more than one current element width from an end produce a calculated current density with less than a 10% departure from the model current density. Certain nonlinear patterns (e.g., V-shaped signatures) in the correlation plots of the two horizontal components of the perturbation magnetic field can be explained in terms of the end field effects of field-aligned current regions. Such signatures can be used to determine the configuration of the satellite track through the current region. C1 ARC PROFESS SERV GRP INC,LANDOVER,MD. RP FUNG, SF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Fung, Shing/F-5647-2012 NR 26 TC 27 Z9 27 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1992 VL 97 IS A6 BP 8569 EP 8579 DI 10.1029/91JA03026 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX984 UT WOS:A1992HX98400037 ER PT J AU AGGSON, TL BURKE, WJ MAYNARD, NC HANSON, WB ANDERSON, PC SLAVIN, JA HOEGY, WR SABA, JL AF AGGSON, TL BURKE, WJ MAYNARD, NC HANSON, WB ANDERSON, PC SLAVIN, JA HOEGY, WR SABA, JL TI EQUATORIAL BUBBLES UPDRAFTING AT SUPERSONIC SPEEDS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID DEPLETED PLASMA REGIONS; SPREAD-F; ELECTRIC-FIELDS; IONOSPHERE; SATELLITE; IRREGULARITIES; MAGNETOSPHERE; CONDUCTIVITY; ALTITUDE; MOTION AB We present plasma and electric field observations from two satellite encounters with equatorial plasma bubbles updrafting at velocities of -2 km/s. These large, upward velocities are consistent with an adaptation of Chandrasekhar's model for the motion of plasma blobs supported against gravity by a magnetic field; that is, V(z) almost-equal-to -g. Vector magnetic field measurements, available during one of the bubble encounters show a perturbation of approximately 150 nT, directed radially outward from the Earth, near the western wall of deepest plasma depletion. This magnetic variation is too large to be caused by simple shunting of the g x B current along the bubble's edge. Rather, it is Alfvenic in nature, radiating from a generator located near the magnetic equator, in the plasma outside the bubble's leading edge. A heuristic model of a depleted flux tube with constant circular cross section moving upward through a background plasma predicts most of the measurements' qualitative features. C1 PHILLIPS LAB,GEOPHYS DIRECTORATE,BEDFORD,MA. UNIV TEXAS,CTR SPACE SCI,RICHARDSON,TX 75080. ST SYST CORP,LANHAM,MD. RP AGGSON, TL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 39 TC 51 Z9 51 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1992 VL 97 IS A6 BP 8581 EP 8590 DI 10.1029/92JA00644 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX984 UT WOS:A1992HX98400038 ER PT J AU CONNERNEY, JEP DESCH, MD AF CONNERNEY, JEP DESCH, MD TI EVIDENCE OF SATURNS MAGNETIC-FIELD ANOMALY FROM SATURNIAN KILOMETRIC RADIATION HIGH-FREQUENCY LIMIT - COMMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID AURORAL-ZONE; SOLAR-WIND; IONOSPHERE; ABSORPTION; VOYAGER-1; MODEL; RINGS RP CONNERNEY, JEP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 695,GREENBELT,MD 20771, USA. RI connerney, john/I-5127-2013; OI connerney, jack/0000-0001-7478-6462 NR 22 TC 11 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUN 1 PY 1992 VL 97 IS A6 BP 8713 EP 8717 DI 10.1029/92JA00139 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX984 UT WOS:A1992HX98400053 ER PT J AU SPALVINS, T AF SPALVINS, T TI LUBRICATION WITH SPUTTERED MOS2 FILMS - PRINCIPLES, OPERATION, AND LIMITATIONS SO JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE LA English DT Article ID MORPHOLOGICAL PROPERTIES; TRIBOLOGICAL PROPERTIES; ELECTRONIC-STRUCTURE; COATINGS AB This article reviews the present practices, limitations, and understanding of thin sputtered MoS2 films. Sputtered MoS2 films can exhibit remarkable tribological properties such as ultra-low friction coefficients (0.01) and enhanced wear lives (millions of cycles) when used in vacuum or dry air. To achieve these favorable tribological characteristics, the sputtering conditions during deposition must be optimized for adequate film adherence and appropriate structure (morphology) and composition. RP SPALVINS, T (reprint author), NATL AERONAUT & SPACE ADM,LEWIS RES CTR,CLEVELAND,OH, USA. NR 22 TC 21 Z9 22 U1 0 U2 4 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 SN 1059-9495 J9 J MATER ENG PERFORM JI J. Mater. Eng. Perform. PD JUN PY 1992 VL 1 IS 3 BP 347 EP 352 DI 10.1007/BF02652388 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA JZ416 UT WOS:A1992JZ41600005 ER PT J AU BANSAL, NP AF BANSAL, NP TI LOW-TEMPERATURE SYNTHESIS OF CAO-SIO2 GLASSES HAVING STABLE LIQUID LIQUID IMMISCIBILITY BY THE SOL-GEL PROCESS SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID SILICA GLASS; SYSTEM AB Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, have been synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol% calcium nitrate, resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water:TEOS mole ratio, calcium content and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(gel), was evaluated from the temperature dependence of the gel time. Neither the presence of Ca2+ ions nor the water:TEOS mole ratio had any appreciable effect on the value of E(gel). The presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, X-ray diffraction, surface-area and pore-size distribution measurements. RP NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 30 TC 11 Z9 11 U1 1 U2 5 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 0022-2461 EI 1573-4803 J9 J MATER SCI JI J. Mater. Sci. PD JUN 1 PY 1992 VL 27 IS 11 BP 2922 EP 2933 DI 10.1007/BF01154101 PG 12 WC Materials Science, Multidisciplinary SC Materials Science GA HY330 UT WOS:A1992HY33000012 ER PT J AU JANG, BZ PATER, RH SOUCEK, MD HINKLEY, JA AF JANG, BZ PATER, RH SOUCEK, MD HINKLEY, JA TI PLASTIC-DEFORMATION MECHANISMS IN POLYIMIDE RESINS AND THEIR SEMIINTERPENETRATING NETWORKS SO JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS LA English DT Article DE POLYIMIDE RESINS AND NETWORKS, PLASTIC DEFORMATION MECHANISMS IN; DEFORMATION MECHANISMS IN THERMOSET AND THERMOPLASTIC POLYIMIDE RESINS; NETWORKS, POLYIMIDE, DEFORMATION MECHANISMS IN ID RUBBER PARTICULATE COMPOSITES; TOUGHENED EPOXY-RESINS; SHEAR DEFORMATION; CROSSLINKED POLYSTYRENE; GLASSY-POLYMERS; PARTICLE-SIZE; FRACTURE; TEMPERATURE; BEHAVIOR; TOUGHNESS AB The plastic deformation mechanisms in both thermoplastic and thermoset polyimide resins and their semi-interpenetrating networks (semi-IPNs) were investigated. The fundamental tendency to undergo strain localization (crazing and shear banding) as opposed to a more diffuse (or homogeneous) deformation in these polymers was evaluated. In situ polarized light microscopic observation of crack-tip deformation mechanisms in solvent-cast films was conducted with a miniature testing device attached to the microscope stage. NASA LaRC TPI, a thermoplastic polyimide, was found to exhibit combined shear yielding and crazing under plane-stress loading conditions. Contrarily, NR-150B2 thermoplastic polyimide exhibited diffuse shear yielding; no shear banding or crazing was found near the crack tip. Adding a small amount of thermoplastic component, either NR-150B2 or LaRC TPI, was found to raise considerably the fracture toughness of PMR-15 thermoset PI. PMR-15 thermoset films also showed diffuse shear yielding, albeit with a much smaller deformation zone. This was consistent with its low toughness and could be understood on the basis of a limited extensibility of a highly crosslinked network. Numerical calculations were performed to confirm this low value of network chain draw ratio. The dimensions of the deformation zone ahead of the crack tip in a semi-IPN with a thermoset matrix were increased as a higher weight fraction of the thermoplastic component was added. The deformation zone size of a thermoplastic matrix was found to decrease with an increasing amount of thermoset PMR-15. Deformation also became more diffuse with a higher PMR-15 content in LaRC TPI. Fracture toughness variations can be correlated with deformation size changes in these semi-IPNs. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP JANG, BZ (reprint author), AUBURN UNIV,201 ROSS HALL,AUBURN,AL 36849, USA. NR 46 TC 11 Z9 11 U1 1 U2 13 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-6266 J9 J POLYM SCI POL PHYS JI J. Polym. Sci. Pt. B-Polym. Phys. PD JUN PY 1992 VL 30 IS 7 BP 643 EP 654 DI 10.1002/polb.1992.090300701 PG 12 WC Polymer Science SC Polymer Science GA HU280 UT WOS:A1992HU28000001 ER PT J AU GOORVITCH, D GALANT, DC AF GOORVITCH, D GALANT, DC TI THE SOLUTION OF COUPLED SCHRODINGER-EQUATIONS USING AN EXTRAPOLATION METHOD SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID OH; CONSTANTS; BANDS AB We apply extrapolation to the limit in a finite-difference method to solve a system of coupled Schrodinger equations. This combination results in a method that only requires knowledge of the potential energy functions for the system. This numerical procedure has several distinct advantages over the more conventional methods such as Numerov's method or the method of finite differences without extrapolation. These advantages are: (i) initial guesses for the term values are not needed; (ii) no assumptions need be made about the behaviour of the wavefunctions such as the slope or magnitude in the non-classical region; (iii) the algorithm is easy to implement, has a firm mathematical foundation and provides error estimates; (iv) the method is less sensitive to round-off error than other methods since a small number of mesh points is used; (v) it can be implemented on small computers. We solve the coupled Schrodinger equation for the X2-PI state of OH. Our algorithm results in term values that agree with experimentally-derived values within 6 parts in 10(4). The calculated wavefunctions are compared indirectly through experimentally-derived rotational constants and are found to be accurate to better than 3 parts in 10(3). A comparison of our method with another numerical method shows results agreeing within 1 part in 10(4). C1 NASA,AMES RES CTR,DIV INFORMAT SYST,MOFFETT FIELD,CA 94035. RP GOORVITCH, D (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 16 TC 8 Z9 8 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD JUN PY 1992 VL 47 IS 6 BP 505 EP 513 DI 10.1016/0022-4073(92)90109-H PG 9 WC Optics; Spectroscopy SC Optics; Spectroscopy GA JB785 UT WOS:A1992JB78500005 ER PT J AU FARLEY, GL DICKINSON, LC AF FARLEY, GL DICKINSON, LC TI REMOVAL OF SURFACE LOOP FROM STITCHED COMPOSITES CAN IMPROVE COMPRESSION AND COMPRESSION-AFTER-IMPACT STRENGTHS SO JOURNAL OF REINFORCED PLASTICS AND COMPOSITES LA English DT Article AB Stitching through-the-thickness (TTT) of composite materials produces a surface loop of yarn between successive penetrations. The surface loop is pressed into the surface layers of the composite material during the curing of the laminate, kinking the in-plane fibers near the surface of the material. The compression strength and compression-after-impact (CAI) strengths of carbon-epoxy specimens were measured with and without the surface loop. Removal of the surface loop had no influence on failure mode or failure mechanism, but did significantly increase the compression and CAI strengths. C1 LOCKHEED ENGN & SCI CO,LANGLEY RES CTR,HAMPTON,VA 23665. RP FARLEY, GL (reprint author), USA,AEROSTRUCT DIRECTORATE,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 8 TC 31 Z9 31 U1 1 U2 1 PU TECHNOMIC PUBL CO INC PI LANCASTER PA 851 NEW HOLLAND AVE, BOX 3535, LANCASTER, PA 17604 SN 0731-6844 J9 J REINF PLAST COMP JI J. Reinf. Plast. Compos. PD JUN PY 1992 VL 11 IS 6 BP 633 EP 642 DI 10.1177/073168449201100604 PG 10 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA HZ620 UT WOS:A1992HZ62000004 ER PT J AU CRANE, C CARNAHAN, T DUFFY, J AF CRANE, C CARNAHAN, T DUFFY, J TI A KINEMATIC ANALYSIS OF THE MODIFIED FLIGHT TELEROBOTIC SERVICER MANIPULATOR SYSTEM SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article AB A reverse analysis of a 6 degree of freedom (dof) subchain of a modified 7 dof flight telerobotic servicer (FTS) manipulator system is presented. The 6 dof subchain is designated as a TR-RT* chain. At the outset, it was considered that the reverse analysis would be similar to a TTT manipulator analyzed previously for which the third and fourth joints intersect at a finite point. This was not, however, the case and a sixteenth-degree tan-half-angle polynomial was derived for the TR-RT manipulator. The elimination procedure is interesting and much simpler than the procedures for the general case. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP CRANE, C (reprint author), UNIV FLORIDA,CTR INTELLIGENT MACHINES & ROBOT,DEPT MECH ENGN,GAINESVILLE,FL 32611, USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD JUN PY 1992 VL 9 IS 4 BP 461 EP 480 DI 10.1002/rob.4620090403 PG 20 WC Robotics SC Robotics GA HV638 UT WOS:A1992HV63800002 ER PT J AU TARN, TJ BEJCZY, AK GANGULY, S AF TARN, TJ BEJCZY, AK GANGULY, S TI FEEDBACK-CONTROL OF ROBOT ARM WITH DISCRETE NONLINEAR MODEL SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article ID TIME-SYSTEMS; LINEARIZATION; MANIPULATORS; INPUT AB This article looks at the problem of controlling a robot arm from a discrete time perspective. We develop the theories and obtain results that feedback linearizes the discrete nonlinear system representing a PUMA 560 robot arm. The effect of sampling on the performance of the arm has been studied and shown through experiments. The results presented here, where the nonlinear robot model has been linearized and controlled completely in discrete time, are new to the robotics literature. We shown certain restrictions necessary on the sampling time of the system. The results obtained have been experimentally verified at the Center for Robotics and Automation at Washington University. Because a number of researchers have addressed the problem of loss of feedback linearizability under sampling, it was important to develop theories and obtain results in discrete time that take into consideration the effects due to sampling. This problem has been addressed here. Analysis of the control law under the assumptions of bounded input is performed and a recursive sensitivity function is derived. The results we obtain in discrete time show the dependency of the performance of the arm on thc sampling time. It has been seen that with a higher sampling frequency the performance of the arm substantially improves and it is expected that close to 1000 Hz sampling rate, the peak performance of the PUMA 560 robot arm, will be reached. C1 JET PROP LAB,PASADENA,CA 91109. AT&T BELL LABS,COLUMBUS,OH 43232. RP TARN, TJ (reprint author), WASHINGTON UNIV,DEPT SYST SCI & MATH,ST LOUIS,MO 63130, USA. NR 32 TC 2 Z9 2 U1 0 U2 1 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD JUN PY 1992 VL 9 IS 4 BP 529 EP 559 DI 10.1002/rob.4620090406 PG 31 WC Robotics SC Robotics GA HV638 UT WOS:A1992HV63800005 ER PT J AU VENKATAKRISHNAN, V SIMON, HD BARTH, TJ AF VENKATAKRISHNAN, V SIMON, HD BARTH, TJ TI A MIMD IMPLEMENTATION OF A PARALLEL EULER SOLVER FOR UNSTRUCTURED GRIDS SO JOURNAL OF SUPERCOMPUTING LA English DT Article DE UNSTRUCTURED GRIDS; EULER EQUATIONS; MIMD COMPUTERS; PARTITIONING OF GRIDS AB A mesh-vertex finite volume scheme for solving the Euler equations on triangular unstructured meshes is implemented on a MIMD (multiple instruction/multiple data stream) parallel computer. Three partitioning strategies for distributing the work load onto the processors are discussed. Issues pertaining to the communication costs are also addressed. We find that the spectral bisection strategy yields the best performance. The performance of this unstructured computation on the Intel iPSC/860 compares very favorably with that on a one-processor CRAY Y-MP/1 and an earlier implementation on the Connection Machine. C1 NASA,AMES RES CTR,COMPUTAT FLUID DYNAM BRANCH,MOFFETT FIELD,CA 94035. RP VENKATAKRISHNAN, V (reprint author), NASA,AMES RES CTR,COMP SCI CORP,NAS APPL RES BRANCH,MS T045-1,MOFFETT FIELD,CA 94035, USA. NR 10 TC 28 Z9 28 U1 1 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0920-8542 J9 J SUPERCOMPUT JI J. Supercomput. PD JUN PY 1992 VL 6 IS 2 BP 117 EP 137 DI 10.1007/BF00129774 PG 21 WC Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA JX860 UT WOS:A1992JX86000002 ER PT J AU CHOI, SR SALEM, JA SANDERS, WA AF CHOI, SR SALEM, JA SANDERS, WA TI ESTIMATION OF CRACK CLOSURE STRESSES FOR INSITU TOUGHENED SILICON-NITRIDE WITH 8 WT-PERCENT SCANDIA SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article DE CRACKS; STRESS; TOUGHENING; SILICON NITRIDE; FRACTURE ID MEASURING FRACTURE-TOUGHNESS; INDENTATION TECHNIQUES; STRENGTH; ALUMINA AB An 8-wt%-scandia silicon nitride with an elongated grain structure was fabricated. The material exhibited high fracture toughness (almost-equal-to 7 MPa.m1/2) and a rising R-curve as measured by the indentation strength technique. The "toughening" exponent m was found to be m almost-equal-to 0.1. The high fracture toughness and R-curve behavior was attributed mainly to bridging of the crack faces by the elongated grains. The crack closure (bridging) stress distribution in the wake region of the crack tip was estimated as a function of crack size from the R-curve data, with an arbitrarily assumed distribution function. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. CLEVELAND STATE UNIV,CLEVELAND,OH 44115. ANALEX CORP,BROOK PK,OH 44142. NR 17 TC 25 Z9 25 U1 0 U2 0 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD JUN PY 1992 VL 75 IS 6 BP 1508 EP 1511 DI 10.1111/j.1151-2916.1992.tb04217.x PG 4 WC Materials Science, Ceramics SC Materials Science GA HZ219 UT WOS:A1992HZ21900031 ER PT J AU JACOBSON, NS LEE, KN FOX, DS AF JACOBSON, NS LEE, KN FOX, DS TI REACTIONS OF SILICON-CARBIDE AND SILICON(IV) OXIDE AT ELEVATED-TEMPERATURES SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article DE SILICON CARBIDE; SILICA; REACTIONS; HIGH TEMPERATURE; KNUDSEN STUDY ID FIBERS AB The reaction between SiC and SiO2 has been studied in the temperature range 1400-1600 K. A Knudsen cell in conjunction with a vacuum microbalance and a high-temperature mass spectrometer was used for this study. Two systems were studied-1:1 SiC (2 wt% excess carbon) and SiO2; and 1:1:1 SiC, carbon, and SiO2. In both cases the excess carbon forms additional SiC within the Knudsen cell and adjusts to the direct reaction of stoichiometric SiC and SiO2 to form SiO(g) and CO(g) in approximately a 3:1 ratio. These results are interpreted in terms of the Si-C-O stability diagram. RP JACOBSON, NS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Jacobson, Nathan/A-9411-2009 NR 20 TC 90 Z9 96 U1 0 U2 13 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD JUN PY 1992 VL 75 IS 6 BP 1603 EP 1611 DI 10.1111/j.1151-2916.1992.tb04232.x PG 9 WC Materials Science, Ceramics SC Materials Science GA HZ219 UT WOS:A1992HZ21900046 ER PT J AU RATNAKUMAR, BV NAGASUBRAMANIAN, G DISTEFANO, S BANKSTON, CP AF RATNAKUMAR, BV NAGASUBRAMANIAN, G DISTEFANO, S BANKSTON, CP TI KINETICS OF INTERCALATION OF LITHIUM INTO NBSE3 AND TIS2 CATHODES SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID NIOBIUM TRISELENIDE CATHODE; POSITIVE ELECTRODES; CELLS; BATTERIES AB Titanium disulfide and niobium triselenide are two well-studied candidate materials for positive electrodes in rechargeable lithium cells. A comparative study of the kinetics of intercalation of lithium in both the cathodes is made here based on various electrochemical techniques, i.e., linear polarization, potentiodynamic polarization, and ac impedance under different experimental conditions such as prismatic or disk configuration of fresh, partially discharged, or cycled electrode. Further, the diffusion coefficients of lithium ions in these cathodes are estimated under these conditions using conventional techniques, i.e., ac impedance, chronocoulometry, chronoamperometry, and current pulse relaxation. Based on the values of the diffusion coefficients, the applicability of these methods for the determination of diffusion coefficients is discussed. RP RATNAKUMAR, BV (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 20 TC 14 Z9 14 U1 0 U2 15 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 10 SOUTH MAIN STREET, PENNINGTON, NJ 08534 SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD JUN PY 1992 VL 139 IS 6 BP 1513 EP 1521 DI 10.1149/1.2069447 PG 9 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA HX978 UT WOS:A1992HX97800008 ER PT J AU SAWKA, MN GREENLEAF, JE AF SAWKA, MN GREENLEAF, JE TI CURRENT CONCEPTS CONCERNING THIRST, DEHYDRATION, AND FLUID REPLACEMENT - OVERVIEW SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Article DE DEHYDRATION; CARBOHYDRATE ELECTROLYTE SOLUTIONS; FLUID REPLACEMENT; FLUID IMBALANCE; REPLACEMENT FLUIDS; HEAT INJURY AB For healthy endurance athletes, two potentially life-threatening medical emergencies are dehydration-mediated heat injuries and hyponatremia. Likewise, dehydration reduces exercise performance via thermoregulatory and cardiovascular impairment as well as electrolyte imbalances. Authors of this symposium integrate new research findings with established concepts concerning the development of dehydration (body water deficit), the physiological and medical consequences of fluid imbalance, and fluid (volume and composition) replacement strategies that minimize the risk of medical emergencies and optimize exercise performance. The following papers provide the readers with an appreciation of the historical development of current concepts and offer an informed opinion concerning fluid replacement strategies for a variety of work performance athletic events. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SAWKA, MN (reprint author), USA,ENVIRONM MED RES INST,NATICK,MA 01760, USA. NR 8 TC 15 Z9 17 U1 0 U2 9 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD JUN PY 1992 VL 24 IS 6 BP 643 EP 644 PG 2 WC Sport Sciences SC Sport Sciences GA HX581 UT WOS:A1992HX58100004 PM 1602936 ER PT J AU GREENLEAF, JE AF GREENLEAF, JE TI PROBLEM - THIRST, DRINKING BEHAVIOR, AND INVOLUNTARY DEHYDRATION SO MEDICINE AND SCIENCE IN SPORTS AND EXERCISE LA English DT Article DE FLUID INTAKE; VASOPRESSIN; ANGIOTENSIN; SODIUM; OSMOLALITY ID VOLUNTARY DEHYDRATION; WATER TEMPERATURE; VASOPRESSIN RELEASE; PLASMA-VOLUME; HUMANS; EXERCISE; HYPOHYDRATION; OSMOLALITY; CONSUMPTION; REHYDRATION AB The phenomenon of involuntary dehydration, the delay in full restoration of a body water deficit by drinking, has been described extensively but relatively little is known about its physiological mechanism. It occurs primarily in humans when they are exposed to various stresses including exercise, environmental heat and cold, altitude, water immersion, dehydration, and perhaps microgravity, singly and in various combinations. The level of involuntary dehydration is approximately proportional to the degree of total stress imposed on the body. Involuntary dehydration appears to be controlled by more than one factor including social customs that influence what is consumed, the capacity and rate of fluid absorption from the gastrointestinal system, the level of cellular hydration involving the osmotic-vasopressin interaction with sensitive cells or structures in the central nervous system, and to a lesser extent, hypovolemic-angiotensin II stimuli. Since humans drink when there is no apparent physiological stimulus, the psychological component should always be considered when investigating the total mechanisms for drinking. RP GREENLEAF, JE (reprint author), NASA,AMES RES CTR,DIV LIFE SCI,HUMAN GRAVITAT PHYSIOL LAB,MOFFETT FIELD,CA 94035, USA. NR 74 TC 203 Z9 210 U1 2 U2 23 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0195-9131 J9 MED SCI SPORT EXER JI Med. Sci. Sports Exerc. PD JUN PY 1992 VL 24 IS 6 BP 645 EP 656 PG 12 WC Sport Sciences SC Sport Sciences GA HX581 UT WOS:A1992HX58100005 PM 1602937 ER PT J AU RAJ, SV AF RAJ, SV TI FRACTURE-BEHAVIOR OF A B2 NI-30AL-20FE-0.05ZR INTERMETALLIC ALLOY IN THE TEMPERATURE-RANGE 300-K TO 1300-K SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID NIAL SINGLE-CRYSTALS; CREEP FRACTURE; MECHANISM MAPS; AL-FE; CERAMICS; DEPENDENCE; ZIRCONIUM; SYSTEMS; GROWTH; METALS AB Tensile tests were conducted on a Ni-30 (at. pct) Al-20Fe-0.05Zr intermetallic alloy in the temperature range 300 to 1300 K under initial strain rates varying between 10(-6) and 10(-3) s-1. The alloy did not exhibit any room-temperature ductility and failed at an average stress of about 710 MPa. The brittle-to-ductile transition temperature (BDTT), which was higher than those for Ni-50Al and Ni-50Al-0.05Zr, was relatively insensitive to strain rate and varied between about 960 K at a nominal strain rate of 1.4 x 10(-5) s-1 to about 990 K at a strain rate of 1.4 x 10(-3) s-1. Detailed observations of the fracture surfaces revealed that cleavage failure had originated at a pre-existing defect in all instances, where the fracture stress, sigma(f), correlated extremely well with the square root of the average defect size, 2c, in accordance with linear elastic fracture mechanics. The average value of the critical stress intensity factor estimated from the sigma(f) - 2c data varied between 4 to 7 MPa m1/2 . A comparison of the fracture map for this intermetallic alloy with those for face-centered cubic (fcc) and refractory body-centered cubic (bcc) metals, alkali halides, refractory oxides, and covalent-bonded ceramics indicated that the low-temperature brittleness of the alloy is, in part, due to mixed atomic bonding. RP RAJ, SV (reprint author), NASA,LEWIS RES CTR,DIV MAT,MS 49-1,CLEVELAND,OH 44135, USA. NR 66 TC 5 Z9 5 U1 2 U2 3 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD JUN PY 1992 VL 23 IS 6 BP 1691 EP 1703 DI 10.1007/BF02804364 PG 13 WC Materials Science, Multidisciplinary SC Materials Science GA HW874 UT WOS:A1992HW87400010 ER PT J AU RAJ, SV LOCCI, IE NOEBE, RD AF RAJ, SV LOCCI, IE NOEBE, RD TI DEFORMATION-BEHAVIOR OF A NI-30AL-20FE-0.05ZR INTERMETALLIC ALLOY IN THE TEMPERATURE-RANGE 300-K TO 1300-K SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID NIAL SINGLE-CRYSTALS; SLOW PLASTIC-FLOW; SUBSTRUCTURE FORMATION; GRAIN-SIZE; CREEP; TRANSITION; DUCTILITY; ZIRCONIUM; SYSTEMS; METALS AB The deformation behavior of an extruded Ni-30 (at. pct) Al-20Fe-0.05Zr intermetallic alloy was studied in the temperature range of 300 to 1300 K under initial tensile strain rates varying between about 10(-6) and 2 x 10(-3) s-1 and in constant load compression creep between 1073 and 1300 K. The deformation microstructures of the fractured specimens were characterized by transmission electron microscopy (TEM). Three deformation regimes were observed: Region I consisted of an athermal regime of low tensile ductility (less than 0.3 pct) occurring between 400 and 673 K, where the substructure consisted of slip bands in a few grains. Exponential creep was dominant in region II between 673 and 1073 K, where the substructure changed from a mixture of dislocation tangles, loops, and dipoles at 673 K to a microstructure consisting of subgrains and dislocation tangles at 973 K. The tensile ductility was generally about 2.0 to 2.5 pct below 980 K in this region. A significant improvement in tensile ductility was observed in region III, which occurred between 1073 and 1300 K. An analysis of the data suggests that viscous glide creep with a stress exponent, n, of about 3 and high-temperature dislocation climb with n almost-equal-to 4.5 where the two dominant creep mechanisms in this region depending on stress and temperature. The average activation energy for deformation in this region was about 310 +/- 30 kJ mol-1 for both processes. In this case, a transition from viscous glide creep to dislocation climb occurred when sigma/E < 1.7 x 10(-4), where sigma is the applied stress and E is the Young's modulus. C1 CASE WESTERN RESERVE UNIV, CLEVELAND, OH 44106 USA. RP NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 62 TC 13 Z9 14 U1 0 U2 2 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 184 THORN HILL RD, WARRENDALE, PA 15086 USA SN 0360-2133 J9 METALL TRANS A PD JUN PY 1992 VL 23 IS 6 BP 1705 EP 1718 DI 10.1007/BF02804365 PG 14 WC Materials Science, Multidisciplinary SC Materials Science GA HW874 UT WOS:A1992HW87400011 ER PT J AU SCHNETZLER, CC AF SCHNETZLER, CC TI MECHANISM OF MUONG NONG-TYPE TEKTITE FORMATION AND SPECULATION ON THE SOURCE OF AUSTRALASIAN TEKTITES SO METEORITICS LA English DT Article ID STREWN FIELD; ELEMENT; ORIGIN AB The source crater of the youngest and largest of the tektite strewnfields, the Australasian strewnfield, has not been located. A number of lines of evidence indicate that the Muong Nong-type tektites, primarily found in Indochina, are more primitive than the much more abundant and widespread splash-form tektites, and are proximal to the source. In this study the spatial distribution of Muong Nong-type tektite sites and chemical character have been used to indicate the approximate location of the source. The variation of Muong Nong-type tektite chemical composition appears to be caused by mixing of two silicate rock end-members and a small amount of limestone, and not by vapor fractionation. The variation in composition is not random, and does not support in-situ melting or multiple impact theories. The distribution of both Muong Nong and splash-form tektite sites suggest the source is in a limited area near the southern part of the Thailand-Laos border. RP SCHNETZLER, CC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. NR 48 TC 54 Z9 54 U1 0 U2 3 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUN PY 1992 VL 27 IS 2 BP 154 EP 165 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JD034 UT WOS:A1992JD03400007 ER PT J AU JONES, KL ROBINSON, RD SLEE, OB STEWART, RT AF JONES, KL ROBINSON, RD SLEE, OB STEWART, RT TI SPECTROSCOPIC INVESTIGATION OF COOL GIANTS AND THE AUTHENTICITY OF THEIR REPORTED MICROWAVE EMISSION SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE STARS, ABUNDANCES; STARS, GIANT; STARS, ROTATION; RADIO CONTINUUM, STARS ID LATE-TYPE STARS; RADIO LUMINOSITY; ROTATION; SPECTRUM AB Anglo-Australian Telescope echelle spectroscopy data have been used to derive surface velocities and metal abundances for 19 red giant stars in the spectral range G5 to M3. These observations were a follow-up to a Parkes 8.4-GHz radio survey which reported that some cool giant stars produced sporadic radio emissions while others of similar spectral type and luminosity class did not. The investigation sought to determine whether the stars reported to emit radio bursts had different physical properties (rotation rate, macroturbulence and microturbulence, metal abundance) from those without the radio bursts, which might explain why they were radio emitters. The data analysis separated the macroturbulent and rotational contributions to the total velocities. The various velocities had values consistent with those previously found for other similar stars. There was an observed increase in both macroturbulent and, less definitely, microturbulent velocities with lateness of spectral type at K3 and later. A weak correlation between surface velocities and 8.4-GHz radio surface fluxes was found. No connection between iron abundances and radio surface fluxes was found. A positive correlation between lithium abundance and sporadic radio emission could suggest emission relatively early in the giant-star phase. However, the weakness of the positive correlations, together with the failure to detect radio emissions from any of the giant stars with the Australia Telescope and a re-examination of the Parkes data, can be combined to throw doubt on the validity of the original Parkes detections. It now appears that few, if any, of the cool giants are radio emitters. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GREENBELT,MD 20771. AUSTRALIA TELESCOPE NATL FACIL,NARRABRI,NSW 2121,AUSTRALIA. RP JONES, KL (reprint author), UNIV QUEENSLAND,DEPT PHYS,BRISBANE,QLD 4072,AUSTRALIA. NR 26 TC 8 Z9 8 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUN 1 PY 1992 VL 256 IS 3 BP 535 EP 544 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW266 UT WOS:A1992HW26600014 ER PT J AU MOORTHI, S SUAREZ, MJ AF MOORTHI, S SUAREZ, MJ TI RELAXED ARAKAWA-SCHUBERT - A PARAMETERIZATION OF MOIST CONVECTION FOR GENERAL-CIRCULATION MODELS SO MONTHLY WEATHER REVIEW LA English DT Article ID LARGE-SCALE ENVIRONMENT; CUMULUS CLOUD ENSEMBLE; SCHEME; WAVE AB A simple implementation of the Arakawa and Schubert (1974) cumulus parameterization is presented. The major simplification made is to "relax" the state toward equilibrium each time the parameterization is invoked, rather than requiring that the final state be balanced, as in the original Arakawa-Schubert implementation. This relaxed Arakawa-Schubert (RAS) scheme is evaluated in off-line tests using the Global Atmospheric Research Program (GARP) Atlantic Tropical Experiment (GATE) Phase III data. The results show that RAS is equivalent to the standard implementation of Arakawa-Schubert but is more economical and simpler to code. RAS also avoids the ill-posed problem that occurs in Arakawa-Schubert as a result of having to solve for a balanced state. RP MOORTHI, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,UNIV SPACE RES ASSOC,CODE 9103,GREENBELT,MD 20771, USA. NR 24 TC 646 Z9 653 U1 4 U2 20 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUN PY 1992 VL 120 IS 6 BP 978 EP 1002 DI 10.1175/1520-0493(1992)120<0978:RASAPO>2.0.CO;2 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HW270 UT WOS:A1992HW27000006 ER PT J AU SCHUBERT, S SUAREZ, M SCHEMM, JK EPSTEIN, E AF SCHUBERT, S SUAREZ, M SCHEMM, JK EPSTEIN, E TI DYNAMICALLY STRATIFIED MONTE-CARLO FORECASTING SO MONTHLY WEATHER REVIEW LA English DT Note ID AVERAGE AB A new method for performing Monte Carlo forecasts is introduced. The method, called dynamic stratification, selects initial perturbations based on a stratification of the error distribution. A simple implementation is presented in which the error distribution used for the stratification is estimated from a linear model derived from a large ensemble of 12-h forecasts with the full dynamical model. The stratification thus obtained is used to choose a small subsample of initial states with which to perform the dynamical Monte Carlo forecasts. Several test cases are studied using a simple two-level general circulation model (GCM) with uncertain initial conditions. It is found that the method provides substantial reductions in the sampling error of the forecast mean and variance when compared to the more traditional approach of choosing the initial perturbations at random. The degree of improvement, however, is sensitive to the nature of the initial error distribution and to the base state. In practice the method may be viable only if the computational burden involved in obtaining an adequate estimate of the error distribution is shared with the data-assimilation procedure. C1 NASA,GODDARD SPACE FLIGHT CTR,GEN SC CORP,GREENBELT,MD 20771. NOAA,NATL WEATHER SERV,CTR CLIMATE ANAL,CAMP SPRINGS,MD. RP SCHUBERT, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,DATA ASSIMILAT OFF,CODE 9103,GREENBELT,MD 20771, USA. NR 8 TC 9 Z9 9 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUN PY 1992 VL 120 IS 6 BP 1077 EP 1088 DI 10.1175/1520-0493(1992)120<1077:DSMCF>2.0.CO;2 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HW270 UT WOS:A1992HW27000011 ER PT J AU PELLIGRA, R NORTON, RD WILKINSON, R LEON, HA MATSON, WR AF PELLIGRA, R NORTON, RD WILKINSON, R LEON, HA MATSON, WR TI RETT SYNDROME - STIMULATION OF ENDOGENOUS BIOGENIC-AMINES SO NEUROPEDIATRICS LA English DT Article DE RETT SYNDROME; NEUROTRANSMITTERS; BIOGENIC AMINES; HYPOXIA; HYPOCAPNIA; CHEYNE-STOKES RESPIRATION ID METABOLITES; GIRLS AB Transient hypercapnic hyperoxemia was induced in two Rett syndrome children by the administration of a gaseous mixture of 80 % O2 and 20 % CO2. Time course studies of neurotransmitters and their metabolites showed an immediate and marked increase in central biogenic amine turnover following inhalation of the gas mixture. The increased turnover of biogenic amines was associated with improved clinical changes. This suggests a coupled relationship and provides further support for an etiological role of neurotransmitter dysfunction in Rett syndrome. In a complementary study, elevation of pulmonary CO2 by application of a simple rebreathing device resulted in improvement of abnormal blood gases and elimination of the Cheyne-Stokes-like respiratory pattern of the Rett syndrome. Near normalization of the EEG occurred when a normal respiratory pattern was imposed by means of a respirator. Taken together, these results lead to the preliminary conclusion that cerebral hypoxemia secondary to abnormal respiratory function may contribute to diminished production of biogenic amines in Rett syndrome. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. ESA LABS,BEDFORD,MA 01173. RP PELLIGRA, R (reprint author), INST ACHIEVEMENT HUMAN POTENTIAL,RESP PHYSIOL LAB,8801 STENTON AVE,PHILADELPHIA,PA 19118, USA. NR 25 TC 6 Z9 7 U1 0 U2 0 PU HIPPOKRATES VERLAG GMBH PI STITTGART PA PO BOX 30 05 04 RUDIGERSTRASSE 14, 70469 STITTGART, GERMANY SN 0174-304X J9 NEUROPEDIATRICS JI Neuropediatrics PD JUN PY 1992 VL 23 IS 3 BP 131 EP 137 DI 10.1055/s-2008-1071328 PG 7 WC Clinical Neurology; Pediatrics SC Neurosciences & Neurology; Pediatrics GA JF636 UT WOS:A1992JF63600004 PM 1353617 ER PT J AU EGALON, CO ROGOWSKI, RS TAI, AC AF EGALON, CO ROGOWSKI, RS TAI, AC TI EXCITATION EFFICIENCY OF AN OPTICAL FIBER CORE SOURCE SO OPTICAL ENGINEERING LA English DT Article DE CIRCULAR OPTICAL FIBER; OPTICAL FLUOROSENSOR; ELECTROMAGNETIC THEORY; STEP-INDEX PROFILE FIBER AB The exact field solution of a step-index profile fiber was used to determine the excitation efficiency of a distribution of sources in the core of an optical fiber. We have compared previous results of a thin-film cladding source distribution to its core source counterpart. The behavior of power efficiency P(eff) with the fiber parameters was examined and found to be similar to the behavior exhibited by cladding sources. It was also found that a core source fiber is two orders of magnitude more efficient than a fiber with a bulk distribution of cladding sources. This result agrees, qualitatively, with previous ones obtained experimentally. C1 COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185. RP EGALON, CO (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 231,HAMPTON,VA 23665, USA. NR 11 TC 3 Z9 3 U1 0 U2 1 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD JUN PY 1992 VL 31 IS 6 BP 1328 EP 1331 DI 10.1117/12.56177 PG 4 WC Optics SC Optics GA HY192 UT WOS:A1992HY19200022 ER PT J AU EGALON, CO ROGOWSKI, RS AF EGALON, CO ROGOWSKI, RS TI MODEL OF AN AXIALLY STRAINED WEAKLY GUIDING OPTICAL FIBER MODAL PATTERN SO OPTICAL ENGINEERING LA English DT Article DE CIRCULAR OPTICAL FIBER; ELECTROMAGNETIC THEORY; ACTIVE MODAL DOMAIN SENSING; STEP-INDEX PROFILE FIBER AB Axial strain can be determined by monitoring the modal pattern variation of an optical fiber. The results of a numerical model developed to calculate the modal pattern variation at the end of a weakly guiding optical fiber under axial strain is presented. Whenever an optical fiber is under stress, the optical path length, the index of refraction, and the propagation constants of each fiber mode change. In consequence, the modal phase term beta(In)z of the fields and the fiber output pattern are also modified. For multimode fibers, very complicated patterns result. The predicted patterns are presented and an expression for the phase variation with strain is derived. RP EGALON, CO (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 231,HAMPTON,VA 23665, USA. NR 22 TC 7 Z9 7 U1 0 U2 0 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD JUN PY 1992 VL 31 IS 6 BP 1332 EP 1339 DI 10.1117/12.56175 PG 8 WC Optics SC Optics GA HY192 UT WOS:A1992HY19200023 ER PT J AU MCFARLAND, M KAYE, J AF MCFARLAND, M KAYE, J TI CHLOROFLUOROCARBONS AND OZONE SO PHOTOCHEMISTRY AND PHOTOBIOLOGY LA English DT Review ID ANTARCTIC OZONE; STRATOSPHERIC OZONE; ULTRAVIOLET-RADIATION; EL-CHICHON; CHLORINE; DEPLETION; PHOTOCHEMISTRY; SPECTROSCOPY; DESTRUCTION; BROMINE C1 NASA,OFF SPACE SCI & APPLICAT EARTH SCI & APPLICAT,WASHINGTON,DC 20546. RP MCFARLAND, M (reprint author), DUPONT CO,CHEM FLUOROCHEM,1007 MARKET ST,WILMINGTON,DE 19898, USA. NR 73 TC 53 Z9 54 U1 1 U2 4 PU AMER SOC PHOTOBIOLOGY PI AUGUSTA PA BIOTECH PARK, 1021 15TH ST, SUITE 9, AUGUSTA, GA 30901-3158 SN 0031-8655 J9 PHOTOCHEM PHOTOBIOL JI Photochem. Photobiol. PD JUN PY 1992 VL 55 IS 6 BP 911 EP 929 DI 10.1111/j.1751-1097.1992.tb08540.x PG 19 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA HX883 UT WOS:A1992HX88300014 PM 1409893 ER PT J AU BHATIA, AK DRACHMAN, RJ AF BHATIA, AK DRACHMAN, RJ TI POLARIZABILITIES OF 2-ELECTRON POSITIVE-IONS AND RYDBERG LEVELS OF LITHIUM SO PHYSICAL REVIEW A LA English DT Article ID ELECTRON; STATES; HELIUM; VALUES; ATOMS AB We have carried out precision calculations of various second-order sums for the two-electron positive ions Li+, Be2+, and B3+. These have the form SIGMA(N)[0\V\N][N\V\0]/(E(N)-E0)k, where k = 1,2,3. The perturbation V is in each case a multipole-potential term, and for k = 1 the sum corresponds to the usual definition of multipole polarizability. The initial state 0 and the intermediate states N are constructed from two-particle Hylleraas basis sets of the appropriate symmetry and angular momentum. Although the set N does not contain any true continuum functions, the pseudostates represent the continuum very well, and excellent convergence is obtained. These two-body quantities are then used to evaluate the energy levels of three-electron systems in high Rydberg states by the asymptotic-optical-potential method previously used for two-electron systems, retaining all terms up to order x(-6). The results are good, but they can be still further improved by including higher-order terms, which will require multiple summation over intermediate states. RP NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. NR 25 TC 30 Z9 30 U1 0 U2 4 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9926 EI 2469-9934 J9 PHYS REV A JI Phys. Rev. A PD JUN 1 PY 1992 VL 45 IS 11 BP 7752 EP 7755 DI 10.1103/PhysRevA.45.7752 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA HX677 UT WOS:A1992HX67700014 ER PT J AU BOZZOLO, G FERRANTE, J AF BOZZOLO, G FERRANTE, J TI HEATS OF FORMATION OF BCC BINARY-ALLOYS SO PHYSICAL REVIEW B LA English DT Article ID ELECTRONIC THEORY; PHASE-STABILITY; DIAGRAMS; AU; AG AB We apply the method of Bozzolo, Ferrante, and Smith for the calculation of alloy energies for bcc elements. The heat of formation of several alloys is computed with the help of the Connolly-Williams method within the tetrahedron approximation. The dependence of the results on the choice of different sets of ordered structures is discussed. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BOZZOLO, G (reprint author), ANALEX CORP,3001 AEROSP PKWY,BROOK PK,OH 44142, USA. NR 10 TC 24 Z9 24 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD JUN 1 PY 1992 VL 45 IS 21 BP 12191 EP 12197 DI 10.1103/PhysRevB.45.12191 PG 7 WC Physics, Condensed Matter SC Physics GA HX378 UT WOS:A1992HX37800001 ER PT J AU WANG, J HASTINGS, DE AF WANG, J HASTINGS, DE TI IONOSPHERIC PLASMA-FLOW OVER LARGE HIGH-VOLTAGE SPACE PLATFORMS .2. THE FORMATION AND STRUCTURE OF PLASMA WAKE SO PHYSICS OF FLUIDS B-PLASMA PHYSICS LA English DT Article ID MESOSONIC CONDUCTING BODIES; SHUTTLE; OBJECT AB Theory and particle simulation results are presented for ionospheric plasma flow over large high-voltage space platforms at a large angle of attack. Both the transient formation of the space-charge wake and its steady-state structure are studied. The wake-side ion impact and current collection are obtained. It is found that the wake behind a high-voltage plate is characterized by two ion-rich sheaths embedded in a quasineutral background wake. The embedded sheath is formed by the ions passing through the sheath around the plate edge and serves as their trajectory path. Depending on the surface potential, the plate dimension, and the angle of attack, the embedded sheath may either extend downstream or curve back to form a "hook" structure. As a result, the plate's wake-side surface may receive a high, localized ion flux at the location the embedded sheath strikes. C1 MIT,CAMBRIDGE,MA 02139. RP WANG, J (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. RI Hastings, Daniel/J-3774-2015 OI Hastings, Daniel/0000-0003-4421-5110 NR 23 TC 17 Z9 17 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8221 J9 PHYS FLUIDS B-PLASMA PD JUN PY 1992 VL 4 IS 6 BP 1615 EP 1629 DI 10.1063/1.860070 PG 15 WC Physics, Fluids & Plasmas SC Physics GA HX374 UT WOS:A1992HX37400030 ER PT J AU BANDY, JA BUNTING, HE GARCIA, MH GREEN, MLH MARDER, SR THOMPSON, ME BLOOR, D KOLINSKY, PV JONES, RJ PERRY, JW AF BANDY, JA BUNTING, HE GARCIA, MH GREEN, MLH MARDER, SR THOMPSON, ME BLOOR, D KOLINSKY, PV JONES, RJ PERRY, JW TI 2ND-ORDER NONLINEAR OPTICAL-PROPERTIES OF DIIRONALKENYLIDYNE COMPLEXES - CRYSTAL-STRUCTURE OF ((ETA-C5H5)2FE2(CO)2(MU-CO)(MU-(E)-C-CH=CH-C6H4-(P)-NME2))+BF4- SO POLYHEDRON LA English DT Article ID MU-VINYLCARBYNE COMPLEXES AB The second-order non-linear optical properties of a series of diironalkenylidyne complexes have been examined by the Kurtz powder technique. One compound, {(eta-C5H5)2Fe2(CO)2(mu-CO)(mu-(E)-C-CH = C6H4-(p)-N(CH3)2)}+CF3SO3-, exhibited a powder efficiency for second harmonic generation 3.6 times that of a urea reference standard (omega = 1907 nm, 2-omega = 953.5 nm). The crystal structure of {(eta-C5H5)2Fe2(CO)2 (mu-CO)(mu-(E)-C-CH = CH-C6H4-(p)-N(CH3)2)}+BF4- has been determined. C1 UNIV OXFORD,S PARKS RD,OXFORD OX1 3QR,ENGLAND. QUEEN MARY COLL,DEPT PHYS,LONDON UE1 4NS,ENGLAND. GEC RES LABS,HIRST RES CTR,WEMBLEY HA9 7PP,MIDDX,ENGLAND. JET PROP LAB,PASADENA,CA 91109. RI Garcia, Maria Helena/H-2175-2013 OI Garcia, Maria Helena/0000-0002-4344-2218 NR 22 TC 37 Z9 37 U1 0 U2 7 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0277-5387 J9 POLYHEDRON JI Polyhedron PD JUN PY 1992 VL 11 IS 12 BP 1429 EP 1435 DI 10.1016/S0277-5387(00)83135-6 PG 7 WC Chemistry, Inorganic & Nuclear; Crystallography SC Chemistry; Crystallography GA JB953 UT WOS:A1992JB95300002 ER PT J AU STEPHENSON, FR AF STEPHENSON, FR TI A REINVESTIGATION OF THE DOUBLE DAWN EVENT RECORDED IN THE BAMBOO ANNALS SO QUARTERLY JOURNAL OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article AB An allusion to a 'double dawn' phenomenon in an ancient Chinese chronicle, which has been identified as caused by a sunrise eclipse occurring in 899 BC, is discussed. This event has been regarded as of considerable importance in the investigation of Earth's past rotation. It is shown that an eclipse interpretation is implausible, not least because the eclipse in question was only annular. C1 JET PROP LAB,PASADENA,CA 91109. NR 15 TC 8 Z9 10 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8738 J9 Q J ROY ASTRON SOC JI Q. J. R. Astron. Soc. PD JUN PY 1992 VL 33 IS 2 BP 91 EP 98 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HX150 UT WOS:A1992HX15000006 ER PT J AU POPE, KO SHEFFNER, EJ LINTHICUM, KJ BAILEY, CL LOGAN, TM KASISCHKE, ES BIRNEY, K NJOGU, AR ROBERTS, CR AF POPE, KO SHEFFNER, EJ LINTHICUM, KJ BAILEY, CL LOGAN, TM KASISCHKE, ES BIRNEY, K NJOGU, AR ROBERTS, CR TI IDENTIFICATION OF CENTRAL KENYAN RIFT-VALLEY FEVER VIRUS VECTOR HABITATS WITH LANDSAT TM AND EVALUATION OF THEIR FLOODING STATUS WITH AIRBORNE IMAGING RADAR SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID POLARIZATION SIGNATURE; FORESTED AREAS; EGYPT 1977-78; SCATTERING AB Rift Valley Fever (RVF) is a mosquito-borne virus that affects livestock and humans in Africa. Landsat Thematic Mapper (TM) data are shown to be effective in identifying dambos, intermittently flooded areas that are potential mosquito breeding sites, in an area north of Nairobi, Kenya. Positive results were obtained from a limited test of flood detection in dambos with airborne high resolution L, C, and X band multipolarization synthetic aperture radar (SAR) imagery. L and C bands were effective in detecting flooded dambos, but LHH was by far the best channel for discrimination (p < 0.01) between flooded and nonflooded sites in both sedge and short grass environments. This study demonstrates the feasibility of a combined passive and active remote sensing program for monitoring the location and condition of RVF vector habitats, thus making future control of the disease more promising. C1 NASA,AMES RES CTR,TGS TECHNOL INC,MS 2424,MOFFETT FIELD,CA 94035. GEO ECO ARC RES,LA CANADA,CA. USA,MED RES INST INFECT DIS,FREDERICK,MD 21701. ENVIRONM RES INST MICHIGAN,ANN ARBOR,MI 48107. USN,CTR AIR DEV,WARMINSTER,PA 18974. KENYA TRYPANOSOMIASIS RES INST,KIKUYU,KENYA. USA,MED RES UNIT,NAIROBI,KENYA. NR 26 TC 59 Z9 65 U1 0 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD JUN PY 1992 VL 40 IS 3 BP 185 EP 196 DI 10.1016/0034-4257(92)90002-2 PG 12 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA HW982 UT WOS:A1992HW98200002 ER PT J AU SMIALEK, JL HUMPHREY, DL AF SMIALEK, JL HUMPHREY, DL TI OXIDATION-KINETICS OF CAST TIAL3 SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID CYCLIC OXIDATION; AL3TI C1 SVERDRUP TECHNOL INC,NASA LEWIS GRP,CLEVELAND,OH. RP SMIALEK, JL (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 18 TC 49 Z9 49 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD JUN 1 PY 1992 VL 26 IS 11 BP 1763 EP 1768 DI 10.1016/0956-716X(92)90549-T PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA HT907 UT WOS:A1992HT90700020 ER PT J AU WAGNER, JA GANGLOFF, RP AF WAGNER, JA GANGLOFF, RP TI FRACTURE-TOUGHNESS OF AN AL-LI-CU-IN ALLOY SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID ALUMINUM-LITHIUM ALLOYS; FATIGUE CRACK-GROWTH; CRYOGENIC TEMPERATURES; BEHAVIOR C1 UNIV VIRGINIA,DEPT MAT SCI & ENGN,CHARLOTTESVILLE,VA 22903. RP WAGNER, JA (reprint author), NASA,LANGLEY RES CTR,METALL MAT BRANCH,HAMPTON,VA 23665, USA. NR 21 TC 6 Z9 6 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD JUN 1 PY 1992 VL 26 IS 11 BP 1779 EP 1784 DI 10.1016/0956-716X(92)90552-P PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA HT907 UT WOS:A1992HT90700023 ER PT J AU VOAS, J AF VOAS, J TI DYNAMIC TESTING COMPLEXITY METRIC SO SOFTWARE QUALITY JOURNAL LA English DT Article DE REVEALING ABILITY; RANDOM TESTING; INPUT DISTRIBUTION; PROGRAM; FAULT; FAILURE ID SOFTWARE AB This paper introduces a dynamic metric that is based on the estimated ability of a program to withstand the effects of injected 'semantic mutants' during execution. Semantic mutants include: (1) syntactic mutants injected into an executing program and (2) randomly selected values injected into an executing program's internal states. The metric is a function of a program, the method used for injecting these two types of mutants, and the program's input distribution; this metric is found through dynamic executions of the program. A program's ability to withstand the effects of injected semantic mutants by computing the same function when executed is then used as a tool for predicting the difficulty that will be incurred during random testing to reveal the existence of faults, i.e., the metric suggests the likelihood that a program will expose the existence of faults during random testing assuming faults were to exist. If the metric is applied to a module rather than to a program, the metric can be used to guide the allocation of testing resources among a program's modules. In this manner the metric acts as a white-box testing tool for determining where to concentrate testing resources. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 22 TC 2 Z9 3 U1 0 U2 0 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0963-9314 J9 SOFTWARE QUAL J JI Softw. Qual. J. PD JUN PY 1992 VL 1 IS 2 BP 101 EP 114 DI 10.1007/BF01845742 PG 14 WC Computer Science, Software Engineering SC Computer Science GA JL365 UT WOS:A1992JL36500003 ER PT J AU BERRY, WL GOLDSTEIN, G DRESCHEL, TW WHEELER, RM SAGER, JC KNOTT, WM AF BERRY, WL GOLDSTEIN, G DRESCHEL, TW WHEELER, RM SAGER, JC KNOTT, WM TI WATER RELATIONS, GAS-EXCHANGE, AND NUTRIENT RESPONSE TO A LONG-TERM CONSTANT WATER DEFICIT SO SOIL SCIENCE LA English DT Article ID PLANT-GROWTH; STRESS; SOIL; CONDUCTANCE; DROUGHT; ADJUSTMENT; SUGARCANE; LEAVES; WHEAT AB Wheat plants (Triticum aestivum) were grown for 43 days in a micro-porous tube nutrient delivery system. Roots were unable to penetrate the microporous tube, but grew on the surface and maintained capillary contact with the nutrient solution on the inside of the tube through the 5-mu-m pores of the porous tube. Water potential in the system was controlled at -0.4, -0.8, and -3.0 kPa by adjusting the applied pressure (hydrostatic head) to the nutrient solution flowing through the microporous tubes. A relatively small decrease in applied water potential from -0.4 to -3.0 kPa resulted in a 34% reduction of shoot growth but only a moderate reduction in the midday leaf water potential from -1.3 to -1.7 MPa. Carbon dioxide assimilation decreased and water use efficiency increased with the more negative applied water potentials, while intercellular CO2 concentration remained constant. This was associated with a decrease in stomatal conductance to water vapor from 1.90 to 0.98 mol m-2s-1 and a decrease in total apparent hydraulic conductance from 47 to 12-mu-mol s-1MPa-1. Although the applied water potentials were in the -0.4 to -3.0 kPa range, the actual water potential perceived by the plant roots appeared to be in the range of -0.26 to -0.38 MPa as estimated by the leaf water potential of bagged plants. The amount of K, Ca, Mg, Zn, Cu, and B accumulated with each unit of transpired water increased as the applied water potential became less negative. The increase in accumulation ranged from 1.4-fold for K to 2.2-fold for B. The physiological responses observed in this study in response to small constant differences in applied water potentials were much greater than expected from either the applied water potential or the observed plant water potential. Even though the micro-porous tube may not represented natural conditions and could possibly introduce morphological and physiological artifacts, it enables a high degree of control of water potential that facilitates the investigation of many aspects of water relations not practical with other experimental systems. C1 UNIV HAWAII,DEPT BOT,HONOLULU,HI 96822. BIONETICS CORP,KENNEDY SPACE CTR,FL 32899. NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899. RP BERRY, WL (reprint author), UNIV CALIF LOS ANGELES,BIOMED & ENVIRONM SCI LAB,LOS ANGELES,CA 90024, USA. OI Dreschel, Thomas/0000-0003-2211-5733 NR 37 TC 7 Z9 7 U1 1 U2 5 PU WILLIAMS & WILKINS PI BALTIMORE PA 351 WEST CAMDEN ST, BALTIMORE, MD 21201-2436 SN 0038-075X J9 SOIL SCI JI Soil Sci. PD JUN PY 1992 VL 153 IS 6 BP 442 EP 451 DI 10.1097/00010694-199206000-00003 PG 10 WC Soil Science SC Agriculture GA JB909 UT WOS:A1992JB90900003 PM 11538048 ER PT J AU JONES, HP DUVALL, TL HARVEY, JW MAHAFFEY, CT SCHWITTERS, JD SIMMONS, JE AF JONES, HP DUVALL, TL HARVEY, JW MAHAFFEY, CT SCHWITTERS, JD SIMMONS, JE TI THE NASA NSO SPECTROMAGNETOGRAPH SO SOLAR PHYSICS LA English DT Article ID MAGNETIC-FIELDS; SOLAR AB The NASA/NSO Spectromagnetograph is a new focal plane instrument for the National Solar Observatory/Kitt Peak Vacuum Telescope which features real-time digital analysis of long-slit spectra formed on a two-dimensional CCD detector. The instrument is placed at an exit port of a Littrow spectrograph and uses an existing modulator of circular polarization. The new instrument replaces the 512-channel Diode Array Magnetograph first used in 1973. Commercial video processing boards are used to digitize the spectral images at video rates and to separate, accumulate, and buffer the spectra in the two polarization states. An attached processor removes fixed-pattern bias and gain from the spectra in cadence with spatial scanning of the image across the entrance slit. The data control computer performs position and width analysis of the line profiles as they are acquired and records line-of-sight magnetic field, Doppler shift, and other computed parameters. The observer controls the instrument through windowed processes on a data control console using a keyboard and mouse. Early observations made with the spectro-magnetograph are presented and plans for future development are discussed. C1 NATL SOLAR OBSERV,TUCSON,AZ. NATL OPT ASTRON OBSERV,TUCSON,AZ. RP JONES, HP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Duvall, Thomas/C-9998-2012 NR 23 TC 107 Z9 107 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD JUN PY 1992 VL 139 IS 2 BP 211 EP 232 DI 10.1007/BF00159149 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA JD790 UT WOS:A1992JD79000001 ER PT J AU BERKE, L HAJELA, P AF BERKE, L HAJELA, P TI APPLICATIONS OF ARTIFICIAL NEURAL NETS IN STRUCTURAL MECHANICS SO STRUCTURAL OPTIMIZATION LA English DT Article AB First the fundamentals of neurologically motivated computing are briefly discussed. This is followed by presenting two of the many possible applications in structural mechanics. Both of these are oriented towards structural optimization. In the first mode a neural net model of the structural response is created and then attached to any conventional optimization algorithm. In the second mode a neural net model of an experienced designer is created knowledgeable within a narrow class of structural concepts. RP BERKE, L (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 30 Z9 30 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0934-4373 J9 STRUCT OPTIMIZATION JI Struct. Optim. PD JUN PY 1992 VL 4 IS 2 BP 90 EP 98 DI 10.1007/BF01759922 PG 9 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary; Mechanics SC Computer Science; Engineering; Mechanics GA KD158 UT WOS:A1992KD15800005 ER PT J AU HOFLUND, GB DAVIDSON, MR OUTLAW, RA AF HOFLUND, GB DAVIDSON, MR OUTLAW, RA TI DEVELOPMENT OF A HYPERTHERMAL OXYGEN-ATOM GENERATOR SO SURFACE AND INTERFACE ANALYSIS LA English DT Article; Proceedings Paper CT EUROPEAN CONF ON APPLICATIONS OF SURFACE AND INTERFACE ANALYSIS ( ECASIA 91 ) CY OCT 14-18, 1991 CL BUDAPEST, HUNGARY SP INT UNION VACUUM SCI TECH & APPL, FEDERAT EUROPEAN CHEM SOCIETIES, WORKING PARTY ANAL CHEM, ACAD SCI HUNGARY, DEPT MATH & PHYS SCI, AMER PHYS SOC, MINIST IND HUNGARY, NATL COMM TECHNOL DEV HUNGARY, SCIENTA INTSRUMENTS, FISONS INSTRUMENTS ID ELECTRON-STIMULATED DESORPTION; AG AB A source that is compact, durable and mounts on a standard ultrahigh vacuum (UHV) flange has been developed for the generation of hyperthermal oxygen atoms. In this source oxygen atoms permeate through an Ag membrane held at 500-degrees-C and are then emitted toward the target from the vacuum side of the membrane by electron-stimulated desorption. The current prototype model generates useable 0-atom fluxes of approximately 10(12) atoms cm-2 s-1, and future modifications should increase this flux by 1-3 orders of magnitude. Based on the O+ energy distribution, the average 0 neutral energy is approximately 5 eV with a fairly broad distribution (full width at half-maximum approximately 3.6 eV). The information required for the development of this source and the design of the source are presented. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP HOFLUND, GB (reprint author), UNIV FLORIDA,DEPT CHEM ENGN,GAINESVILLE,FL 32611, USA. RI Davidson, Mark/C-1135-2009 NR 15 TC 7 Z9 7 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0142-2421 J9 SURF INTERFACE ANAL JI Surf. Interface Anal. PD JUN PY 1992 VL 19 IS 1-12 BP 325 EP 330 DI 10.1002/sia.740190161 PG 6 WC Chemistry, Physical SC Chemistry GA JD452 UT WOS:A1992JD45200058 ER PT J AU DRAWDY, JE HOFLUND, GB DAVIDSON, MR UPCHURCH, BT SCHRYER, DR AF DRAWDY, JE HOFLUND, GB DAVIDSON, MR UPCHURCH, BT SCHRYER, DR TI CHARACTERIZATION STUDY OF POLYCRYSTALLINE TIN OXIDE SURFACES BEFORE AND AFTER REDUCTION IN CO SO SURFACE AND INTERFACE ANALYSIS LA English DT Article; Proceedings Paper CT EUROPEAN CONF ON APPLICATIONS OF SURFACE AND INTERFACE ANALYSIS ( ECASIA 91 ) CY OCT 14-18, 1991 CL BUDAPEST, HUNGARY SP INT UNION VACUUM SCI TECH & APPL, FEDERAT EUROPEAN CHEM SOCIETIES, WORKING PARTY ANAL CHEM, ACAD SCI HUNGARY, DEPT MATH & PHYS SCI, AMER PHYS SOC, MINIST IND HUNGARY, NATL COMM TECHNOL DEV HUNGARY, SCIENTA INTSRUMENTS, FISONS INSTRUMENTS ID RAY PHOTOELECTRON-SPECTROSCOPY; DEFECT ELECTRONIC STATES; METHANOL FUEL-CELLS; THIN-FILMS; SNO2(110)-1X1 SURFACE; OXYGEN-CHEMISORPTION; OXIDATION; CATALYSTS; PLATINUM; CONVERSION AB Polycrystalline tin oxide surfaces have been examined before and after reduction in 40 Torr of CO at 100 and 175-degrees-C using Auger electron spectroscopy (AES), electron spectroscopy for chemical analysis (ESCA), ion-scattering spectroscopy (ISS) and electron-stimulated desorption (ESD). The changes in the surface composition and chemical states of the surface species generally are subtle for the reductive conditions used. Some of the SnO2 is reduced to SnO and significant changes do occur with regard to the amounts and chemical forms of the hydrogen-containing species remaining after both the 100 and 175-degrees-C reductions. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP DRAWDY, JE (reprint author), UNIV FLORIDA,DEPT CHEM ENGN,GAINESVILLE,FL 32611, USA. RI Davidson, Mark/C-1135-2009 NR 52 TC 14 Z9 14 U1 2 U2 3 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0142-2421 J9 SURF INTERFACE ANAL JI Surf. Interface Anal. PD JUN PY 1992 VL 19 IS 1-12 BP 559 EP 564 DI 10.1002/sia.7401901104 PG 6 WC Chemistry, Physical SC Chemistry GA JD452 UT WOS:A1992JD45200101 ER PT J AU MORIKAWA, K MCBEATH, MK AF MORIKAWA, K MCBEATH, MK TI LATERAL MOTION BIAS ASSOCIATED WITH READING DIRECTION SO VISION RESEARCH LA English DT Article DE MOTION PERCEPTION; LATERAL MOTION; APPARENT MOTION; SACCADES; READING; HANDEDNESS; LATERALIZATION ID VISUAL EVOKED-POTENTIALS; APPARENT MOTION; EYE-MOVEMENTS; AESTHETIC PREFERENCE; HUMAN-VISION; PERCEPTION; ASYMMETRY; SYSTEMS; STIMULI AB We found that when Americans view ambiguous lateral long-range apparent motion, they exhibit a robust bias to experience leftward movement. In successive experiments, right-handers and left-handers, and left-side drivers from Japan equally manifested this leftward bias. However, bilingual viewers whose first language reads from right to left exhibited no lateral bias. Furthermore, the bilingual sample produced a significant correlation between exposure to English and extent of leftward motion bias. The findings provide strong evidence that reading habits can influence directionality in motion perception. C1 NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MOFFETT FIELD,CA 94035. RP MORIKAWA, K (reprint author), STANFORD UNIV,DEPT PSYCHOL,JORDAN HALL,BLDG 420,STANFORD,CA 94305, USA. NR 33 TC 42 Z9 42 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0042-6989 J9 VISION RES JI Vision Res. PD JUN PY 1992 VL 32 IS 6 BP 1137 EP 1141 DI 10.1016/0042-6989(92)90014-A PG 5 WC Neurosciences; Ophthalmology SC Neurosciences & Neurology; Ophthalmology GA HW376 UT WOS:A1992HW37600014 PM 1509704 ER PT J AU GOLUB, MA WYDEVEN, T AF GOLUB, MA WYDEVEN, T TI WASTE STREAMS IN A CREWED SPACE HABITAT-II SO WASTE MANAGEMENT & RESEARCH LA English DT Article DE WASTE STREAMS; CREWED SPACE HABITAT; ENVIRONMENTAL CONTROL DESIGN PARAMETERS; TRACE CONTAMINANTS; HUMAN BODY WASTES; LONG-DURATION SPACE MISSIONS; NASA RP GOLUB, MA (reprint author), NASA,AMES RES CTR,DIV ADV LIFE SUPPORT,MOFFETT FIELD,CA 94035, USA. NR 0 TC 1 Z9 1 U1 0 U2 7 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0734-242X J9 WASTE MANAGE RES JI Waste Manage. Res. PD JUN PY 1992 VL 10 IS 3 BP 269 EP 280 PG 12 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA JB289 UT WOS:A1992JB28900005 PM 11537495 ER PT J AU SCHMALZER, PA HINKLE, CR AF SCHMALZER, PA HINKLE, CR TI SOIL DYNAMICS FOLLOWING FIRE IN JUNCUS AND SPARTINA MARSHES SO WETLANDS LA English DT Article DE FIRE; JUNCUS-ROEMERIANUS; MARSHES; NUTRIENTS; SOIL; SPARTINA-BAKERI AB We examined soil changes in the 0-5 and 5-15 cm layers for one year after a fire in burned Juncus roemerianus and Spartina bakeri marshes and an unburned Juncus marsh. Each marsh was sampled (N = 25) preburn, immediately postburn, and 1, 3, 6, 9, and 12 months postburn. All marshes were flooded at the time of the fire; water levels declined below the surface by 6 months but reflooded at 12 months after the fire. Soil samples were analyzed for pH, conductivity, organic matter, exchangeable Ca, Mg, and K, available PO4-P, total Kjeldahl nitrogen (TKN), exchangeable NO3-N, NO2-N, and NH4-N. Changes due to burning were most pronounced in the surface (0-5 cm) layer. Soil pH increased 0.16-0.28 units immediately postburn but returned to preburn levels in 1 month. Organic matter increased by 1 month and remained elevated through 9 months after the fire. Calcium, Mg, K, and PO4-P all increased by 1 month after burning, and the increases persisted for 6 to 12 months. Conductivity increased in association with these cations. Burning released ions from organic matter as indicated by the increase in pH, conductivity, Ca, Mg, K, and PO4-P. NH4-N in burned marshes was elevated 6 months and NO3-N 12 months after burning. TKN showed seasonal variations but no clear fire-related changes. Nitrogen species were affected by the seasonally varying water levels as well as fire; these changes differed from those observed in many upland systems. RP SCHMALZER, PA (reprint author), BIONET CORP,NASA,BIOMED OPERAT & RES OFF,MAIL CODE BIO2,KENNEDY SPACE CTR,FL 32899, USA. OI Schmalzer, Paul/0000-0003-2214-0074 NR 0 TC 10 Z9 12 U1 0 U2 5 PU SOC WETLAND SCIENTISTS PI LAWRENCE PA 810 E TENTH ST, P O BOX 1897, LAWRENCE, KS 66044 SN 0277-5212 J9 WETLANDS JI Wetlands PD JUN PY 1992 VL 12 IS 1 BP 8 EP 21 PG 14 WC Ecology; Environmental Sciences SC Environmental Sciences & Ecology GA HU108 UT WOS:A1992HU10800002 ER PT J AU TSAY, SC STAMNES, K AF TSAY, SC STAMNES, K TI ULTRAVIOLET-RADIATION IN THE ARCTIC - THE IMPACT OF POTENTIAL OZONE DEPLETIONS AND CLOUD EFFECTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MULTIPLE-SCATTERING; SOLAR-RADIATION; PHOTODISSOCIATION RATES; DYNAMICAL RESPONSE; ANTARCTICA; MODEL; UV; PARAMETERIZATION; ATMOSPHERES; ABSORPTION AB An atmospheric radiation model is used to study the combined effects of ozone depletions/redistributions and particulate clouds on atmospheric heating/photolysis rates and ultraviolet radiation reaching the biosphere. Four types of particulate clouds prevalent in the summertime Arctic are considered: stratospheric aerosols, tropospheric aerosols (Arctic haze), cirrus clouds, and stratus clouds. The effects of ozone depletion and vertical redistributions of ozone are also examined. The main findings are as follows: (1) stratus clouds provide significant protection from ultraviolet radiation exposure, but while stratospheric aerosols imply increased UVB exposure, Arctic haze results in a decrease; (2) a redistribution of ozone from the stratosphere to the troposphere tends to decrease UV exposure, but for low solar elevations an increase may occur, (3) a 20% ozone depletion leads to about 0.4 K/d cooling in the lower stratosphere, while redistribution of ozone from the stratosphere to the troposphere implies a warming of about 0.015 K/d in the upper troposphere; (4) stratus clouds may cause a large warming in the middle and upper stratosphere (0.8 K/d); (5) clouds have little effect on ozone photolysis leading to O(1D) production at altitudes higher than 25 lan; (6) for ozone photolysis leading to O(3P) production photolysis rates may increase by 50% or more throughout the atmosphere due to multiple scattering by stratus clouds. C1 UNIV ALASKA, INST GEOPHYS, FAIRBANKS, AK 99775 USA. UNIV ALASKA, DEPT PHYS, FAIRBANKS, AK 99775 USA. RP TSAY, SC (reprint author), NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, CODE 913, GREENBELT, MD 20771 USA. RI Tsay, Si-Chee/J-1147-2014 NR 50 TC 59 Z9 59 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7829 EP 7840 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900003 ER PT J AU ROSENFIELD, JE AF ROSENFIELD, JE TI RADIATIVE EFFECTS OF POLAR STRATOSPHERIC CLOUDS DURING THE AIRBORNE ANTARCTIC OZONE EXPERIMENT AND THE AIRBORNE ARCTIC STRATOSPHERIC EXPEDITION SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TOTAL REACTIVE NITROGEN; HEATING RATES; NITRIC-ACID; DIABATIC CIRCULATION; SOLAR-RADIATION; WATER-VAPOR; HOLE; WINTER; ER-2; ABSORPTION AB Daily, three dimensional fields of both Type I nitric acid trihydrate (N AT) and Type 11 water ice polar stratospheric clouds (PSCs) have been generated in the polar regions during the period of the Airborne Antarctic Ozone Experiment (AAOE) and the Airborne Arctic Stratospheric Expedition (AASE) aircraft missions. Mission data on particulate composition and size, together with National Meteorological Center (NMC) analyzed temperatures, have been used. A comparison of computed 1-mu-m extinction coefficients with those observed by the Stratospheric Aerosol Measurement (SAM II) satellite served to constrain the water ice particle size and the nitric acid mixing ratio profiles. For AAOE, both Type I and Type II clouds were formed for the time period August 23 to September 17, after which only Type I clouds formed. During AASE, while Type I clouds were formed for each day between January 3 and February 10, Type Il clouds formed on only two days, January 24 and 31. Mie theory and a radiative transfer model were used to compute the radiative heating rates during the mission periods, for clear and cloudy lower sky cases. Only the Type II water ice clouds have a significant radiative effect, with the Type I NAT PSCs generating a net heating or cooling of 0.1 K/d or less. The major effect of PSCs during AAOE appears to be one of net heating, with maximum heating rates as large as 0.5 K/d for particular days. Heating rates of 0.3 K/d or greater were computed during the periods September 1-6 and September 11-14. This additional heating was generally found over the western part of Antarctica and near the coastal regions, while a small cooling was computed over the Antarctic Plateau. However, when the heating rates are averaged over the AAOE mission, a net heating on the order of only 0.1 K/d is generated by the PSCs over western Antarctica, with other regions exhibiting a very small additional cooling, less than 0.05 K/d. Tropospheric clouds turn this net heating to a small amount of net cooling, roughly 0.1 K/d. The average effect of PSCs to the radiative budget during AASE is extremely small. Therefore, on the whole, the radiative effects of PSCs appear to be too small to have an appreciable impact on vertical motions except over time scales of a few days during AAOE. This result makes it unlikely that the radiative-dynamical mechanisms proposed for the Antarctic ozone depletion play any significant role. RP ROSENFIELD, JE (reprint author), NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, ATMOSPHERES LAB, CODE 916, GREENBELT, MD 20771 USA. NR 52 TC 15 Z9 15 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7841 EP 7858 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900004 ER PT J AU SCHOEBERL, MR LAIT, LR NEWMAN, PA ROSENFIELD, JE AF SCHOEBERL, MR LAIT, LR NEWMAN, PA ROSENFIELD, JE TI THE STRUCTURE OF THE POLAR VORTEX SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE HOLE; ELIASSEN-PALM FLUX; TRANSPORT CHARACTERISTICS; AIRCRAFT MEASUREMENTS; STRATOSPHERIC CLOUDS; ARCTIC STRATOSPHERE; GENERAL-CIRCULATION; MIDDLE ATMOSPHERE; SEPTEMBER 1987; LATE WINTER AB Reconstruction of the Airborne Antarctic Ozone Experiment and Airborne Arctic Stratosphere Expedition aircraft constituent observations, radiative heating rate computations, and trajectory calculations are used to generate comparative pictures of the 1987 southern hemisphere (SH) late winter and 1989 northern hemisphere (NH) mid-winter, lower stratospheric, polar vortices. Overall, both polar vortices define a region of highly isolated air, where the exchange of trace gases occurs principally at the vortex edge through erosional wave activity. Aircraft measurement showed that (1) between 50 and 100 mbar, horizontally stratified long-lived tracers such as N2O are displaced downward 2-3 km on the cyclonic (poleward) side of the jet with the meridional tracer gradient sharpest at the jet core. (2) Eddy mixing rates, computed using parcel ensemble statistics, are an order of magnitude or more lower on the cyclonic side of the jet compared to those on the anticyclonic side. (3) Poleward zonal mean meridional flow on the anticyclonic side of the jet terminates in a descent zone at the jet core. Despite the similarities between the SH and NH winter vortices, there are important differences. During the aircraft campaign periods, the SH vortex jet core was located roughly 8-degrees - 10-degrees equatorward of its NH counterpart after pole centering. As a result of the larger size of the SH vortex, the dynamical heating associated with the jet core descent zone is displaced further from the pole. The SH polar vortex can therefore approach radiative equilibrium temperatures over a comparatively larger area than the NH vortex. The subsequent widespread formation of polar stratospheric clouds within the much colder SH vortex core gives rise to the interhemispheric differences in the reconstructed H2O, NOy, ClO, and O3, species which are affected by polar stratospheric clouds. RP SCHOEBERL, MR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, CODE 916, GREENBELT, MD 20771 USA. RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 69 TC 276 Z9 276 U1 2 U2 23 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7859 EP 7882 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900005 ER PT J AU TUCK, AF DAVIES, T HOVDE, SJ NOGUERALBA, M FAHEY, DW KAWA, SR KELLY, KK MURPHY, DM PROFFITT, MH MARGITAN, JJ LOEWENSTEIN, M PODOLSKE, JR STRAHAN, SE CHAN, KR AF TUCK, AF DAVIES, T HOVDE, SJ NOGUERALBA, M FAHEY, DW KAWA, SR KELLY, KK MURPHY, DM PROFFITT, MH MARGITAN, JJ LOEWENSTEIN, M PODOLSKE, JR STRAHAN, SE CHAN, KR TI POLAR STRATOSPHERIC CLOUD PROCESSED AIR AND POTENTIAL VORTICITY IN THE NORTHERN-HEMISPHERE LOWER STRATOSPHERE AT MIDLATITUDES DURING WINTER SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE EXPERIMENT; TOTAL REACTIVE NITROGEN; 1988/89 ARCTIC WINTER; ER-2 AIRCRAFT; INSITU OBSERVATIONS; VORTEX; TRACER; MODEL; DEHYDRATION; EXPEDITION AB Small-scale (<1000 km) features in ER-2 measurements of ClO, O3, H2O, N2O, and NOy outside the lower stratospheric Arctic vortex of 1988-1989 are compared with features on potential vorticity maps from the European Centre for Medium-range Weather Forecasts (ECMWF). The potential vorticity maps are obtained from T106 analyses and forecasts. Some of the plots have been truncated to lower resolution (T63 or T42) which smooths out the finer-scale structure. Comparison of these lower resolution plots shows how much detail is lost by excessive smoothing. It is also evident that the forecast plots lose fine-scale structure due to dissipation in the model resulting mainly from horizontal diffusion. We conclude that blobs of air on the maps at latitudes between the vortex edge and 25-degrees-N having potential vorticities characteristic of the vortex, did indeed originate from the vortex, but that the real atmosphere is more sharply differentiated (inhomogeneous) than the meteorological analyses, implying that the potential vorticity maps underestimate the amount of peeled-off material. Areal budgets of thc ex-vortex air are considered for ER-2 flight days, and are performed for 24-hour forecasts at T63, and analyses at T42, T63, and T106 resolution at theta = 475 K. Finally, it is concluded that the lower stratospheric Arctic vortex of 1988-1989 spread considerable amounts of air to mid-latitudes which had been processed by polar stratospheric clouds, and that this mechanism is a realistic explanation for the wintertime loss of ozone observed over northern mid-latitudes during the last decade. C1 UNIV COLORADO, NOAA, COOPERAT INST RES ENVIRONM SCI, COOPERAT INST ENVIRONM SCI, BOULDER, CO 80309 USA. NOAA, GEOPHYS FLUID DYNAM LAB, PRINCETON, NJ USA. JET PROP LAB, PASADENA, CA 91109 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. EUROPEAN CTR MEDIUM RANGE WEATHER FORECASTS, READING RG2 9AX, ENGLAND. RP TUCK, AF (reprint author), NOAA, AERON LAB, BOULDER, CO 80303 USA. RI Tuck, Adrian/F-6024-2011; Kawa, Stephan/E-9040-2012; Strahan, Susan/H-1965-2012; Murphy, Daniel/J-4357-2012; Fahey, David/G-4499-2013 OI Tuck, Adrian/0000-0002-2074-0538; Murphy, Daniel/0000-0002-8091-7235; Fahey, David/0000-0003-1720-0634 NR 44 TC 95 Z9 96 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7883 EP 7904 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900006 ER PT J AU KAWA, SR FAHEY, DW HEIDT, LE POLLOCK, WH SOLOMON, S ANDERSON, DE LOEWENSTEIN, M PROFFITT, MH MARGITAN, JJ CHAN, KR AF KAWA, SR FAHEY, DW HEIDT, LE POLLOCK, WH SOLOMON, S ANDERSON, DE LOEWENSTEIN, M PROFFITT, MH MARGITAN, JJ CHAN, KR TI PHOTOCHEMICAL PARTITIONING OF THE REACTIVE NITROGEN AND CHLORINE RESERVOIRS IN THE HIGH-LATITUDE STRATOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE HOLE; WINTER POLAR STRATOSPHERES; NITRIC-ACID TRIHYDRATE; 1988/89 ARCTIC WINTER; ER-2 AIRCRAFT; HETEROGENEOUS REACTIONS; HYDROGEN-CHLORIDE; CHEMICAL-COMPOSITION; INSITU OBSERVATIONS; SEPTEMBER 1987 AB Partitioning of the major components of the reactive nitrogen and inorganic chlorine reservoirs is derived from aircraft measurements in the lower stratosphere during the winter season in both hemispheres at latitudes of about 60-degrees to 80-degrees. The goal of this work is to exercise the power of the correlated set of measurements from polar missions of the NASA ER-2 to extend what can be learned from looking at the measurements individually. The results provide a consistent method for comparing distributions, and hence the controlling processes, between different areas of the near-polar regions. The analysis provides clear evidence of the effects of heterogeneous processes in the atmosphere. Values for NO2, ClONO2, N2O5, and Cl2O2 are derived in a simplified steady state model based on in situ NO, ClO, O3, temperature, and pressure measurements; laboratory-measured reaction rates; and modeled photodissociation rates. Values for the reservoir totals are independently derived from measurements of N2O, organic chlorine, and total reactive nitrogen. The relative abundances of the measured and derived species within the reservoirs are calculated, and the longer-lived species HCI and HNO3 are estimated as the residuals of their respective reservoirs. The resulting latitude distributions in the Arctic outside the vortex agree reasonably well with predictions of a two-dimensional photochemical model, indicating that partitioning in this region is largely controlled by standard homogeneous gas phase chemistry. Inside the Arctic vortex a large fraction of the HCl has been converted to reactive chlorine species CIO and Cl2O2, consistent with the extensive action of known heterogeneous reactions, presumably occurring on the surfaces of polar stratospheric clouds formed in the cold temperatures of the vortex. The partitioning in the Antarctic suggests that nearly the entire range of latitudes sampled by the ER-2 is affected by heterogeneous processes in situ, including that portion of the "collar" region equatorward of the nominal chemically perturbed region (CPR). Consideration of heterogeneous processing in the region outside the CPR is important in predicting the possible expansion of Antarctic ozone depletion and the transport of chemically perturbed air to lower latitudes. C1 COMPUTAT PHYS INC, ANNANDALE, VA USA. UNIV COLORADO, NOAA, COOPERAT INST RES ENVIRONM SCI, BOULDER, CO 80309 USA. NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. JET PROP LAB, PASADENA, CA 91109 USA. RP KAWA, SR (reprint author), NOAA, AERON LAB, 325 BROADWAY, BOULDER, CO 80303 USA. RI Kawa, Stephan/E-9040-2012; Fahey, David/G-4499-2013 OI Fahey, David/0000-0003-1720-0634 NR 79 TC 84 Z9 84 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7905 EP 7923 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900007 ER PT J AU KAWA, SR FAHEY, DW KELLY, KK DYE, JE BAUMGARDNER, D GANDRUD, BW LOEWENSTEIN, M FERRY, GV CHAN, KR AF KAWA, SR FAHEY, DW KELLY, KK DYE, JE BAUMGARDNER, D GANDRUD, BW LOEWENSTEIN, M FERRY, GV CHAN, KR TI THE ARCTIC POLAR STRATOSPHERIC CLOUD AEROSOL - AIRCRAFT MEASUREMENTS OF REACTIVE NITROGEN, TOTAL WATER, AND PARTICLES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE EXPERIMENT; NITRIC-ACID; CONDENSATION NUCLEI; LIDAR OBSERVATIONS; AIRBORNE LIDAR; JANUARY 24; WINTER; DEHYDRATION; EXPEDITION; DENITRIFICATION AB The reactive nitrogen (NOy), total water, and particle components of the polar stratospheric cloud (PSC) aerosol in the Arctic am studied using in situ aircraft measurements in the lower stratosphere. The results are compared to findings from the Antarctic derived using similar measurements and interpretive techniques. The Arctic data show that particle volume well above background values is present at temperatures above the frostpoint. confirming the result from the Antarctic that the observed PSC's are not water ice particles. NOy measurements inside a PSC are enhanced above ambient values consistent with anisokinetic sampling of particles containing NOy. Furthermore, relative changes in the measured particle volume along a flight track are well correlated with changes in the amount of NOy estimated to be in the particle phase. With the exception of data from one flight, assuming that the composition of the PSC particles is nitric acid trihydrate (NAT), the HNO3 content of the measured panicle volume is consistent with the amount of HNO3 Predicted to be available for condensation. To this extent, the Arctic observations are consistent with NAT as the composition of PSC panicles, in agreement With the Antarctic findings. In the Arctic data over long segments of several flights, calculations show saturation with respect to NAT without significant PSC particle growth above background. PSCs in the Arctic are not observed in situ until the apparent saturation ratio of HNO3 with respect to NAT is greater than 10, in marked contrast to the Antarctic, where PSCs are observed in conditions of apparent HNO3 saturation of 1 and above. This difference cannot be resolved by known measurement uncertainties. Also, a discrepancy is noted in the comparison of the amount of condensed HNO3 derived from the particle distribution measurements with that derived from the NO, measurements, assuming a NAT composition for the particles. Although thc relative variations in the derived quantities are similar, as in the Antarctic, the mean values consistently disagree by about a factor of 2. The differences suggest that there may be systematic errors in the data and/or physical assumptions used in the analysis. Several possibilities are discussed. C1 NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP KAWA, SR (reprint author), NOAA, AERON LAB, 325 BROADWAY, BOULDER, CO 80303 USA. RI Kawa, Stephan/E-9040-2012; Fahey, David/G-4499-2013 OI Fahey, David/0000-0003-1720-0634 NR 52 TC 65 Z9 65 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7925 EP 7938 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900008 ER PT J AU TOON, GC FARMER, CB SCHAPER, PW LOWES, LL NORTON, RH AF TOON, GC FARMER, CB SCHAPER, PW LOWES, LL NORTON, RH TI COMPOSITION MEASUREMENTS OF THE 1989 ARCTIC WINTER STRATOSPHERE BY AIRBORNE INFRARED SOLAR ABSORPTION-SPECTROSCOPY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID AIRCRAFT MEASUREMENTS; JUNGFRAUJOCH STATION; LIDAR OBSERVATIONS; ANTARCTICA; OZONE; COLUMN; HCL; CLOUDS; VORTEX; HF AB Simultaneous measurements of the stratospheric burdens of H2O, HDO, OCS, CO2, O3, N2O, CO, CH4, CF2Cl2, CFCl3, CHF2Cl, C2H6, HCN, NO, NO,, HNO3, ClNO3, HOCl, HCl, and HF were made by the Jet Propulsion Laboratory MkIV interferometer on board the NASA DC-8 aircraft during January and early February 1989 as part of the Airborne Arctic Stratosphere Experiment (AASE). Data were acquired on 11 flights at altitudes of up to 12 km over a geographic region covering the NE Atlantic Ocean, Iceland, and Greenland. Analyses of the chemically active gases reveal highly perturbed conditions within the vortex. The ClNO3 abundance was chemically enhanced near the edge of the vortex but was then depleted inside. HCI was chemically depleted near the vortex edge and became even more depleted inside. In fact, by late January deep inside the vortex, HCI was either completely removed up to 27-km altitude, or partially removed to an even greater altitude. NO2 was also severely depleted inside the vortex. In contrast to Antarctica, H2O and HNO3 were both more abundant inside the vortex than outside. While for H2O this is solely a consequence of descent (without accompanying dehydration), HNO3 additionally shows evidence for chemical enhancement inside the vortex. One exception to the high HNO3 abundances inside the vortex occurred on January 31 when stratospheric temperatures above the aircraft fell below 190 K. However, following this event, HNO3 burdens fully recovered, suggesting that if the loss on January 31 was due to temporary freeze-out of HNO3, the resulting particles reevaporated above 12 km. Taken together, these results suggest that although the Arctic vortex did not get cold enough to produce any dehydration, nor as vertically extensive denitrification as occurred in Antarctica, nevertheless, enough heterogeneous chemistry still occurred to convert over 90% of the inorganic chlorine to active forms in the 14- to 27-km altitude range by early February 1989. RP TOON, GC (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 35 TC 79 Z9 79 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7939 EP 7961 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900009 ER PT J AU TOON, GC FARMER, CB SCHAPER, PW LOWES, LL NORTON, RH SCHOEBERL, MR LAIT, LR NEWMAN, PA AF TOON, GC FARMER, CB SCHAPER, PW LOWES, LL NORTON, RH SCHOEBERL, MR LAIT, LR NEWMAN, PA TI EVIDENCE FOR SUBSIDENCE IN THE 1989 ARCTIC WINTER STRATOSPHERE FROM AIRBORNE INFRARED COMPOSITION MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MCMURDO-STATION; N2O; ANTARCTICA; CONSTITUENTS; TRACER; O-3 AB Simultaneous measurements of the stratospheric burdens of CO2, HCN, N2O, CH4, OCS, CF2Cl2, CFCl3, CHF2Cl and HF were made by the Jet Propulsion Laboratory MkIV interferometer on board the NASA DC-8 aircraft during January and early February 1989 as part of the Airborne Arctic Stratosphere Experiment. Data were acquired on 11 flights at altitudes of up to 12 km over a geographic region covering the NE Atlantic Ocean, Iceland and Greenland. The results obtained show large variations in the burdens of these tracers due to the effects of transport. The tropospheric source gas burdens were reduced inside the polar vortex, suggesting that the air had subsided with respect to the surrounding mid-latitude air. Increased HF burdens inside the vortex support this interpretation. The results obtained from the different tracers are highly consistent with each other and indicate that in the 15- to 20-km altitude range inside the vortex, surfaces of constant volume mixing ratio were located some 5-6 km lower in absolute altitude than outside the vortex. The results also indicate that the magnitude of this subsidence increases with altitude. These conclusions are consistent with other measurements. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP TOON, GC (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 17 TC 40 Z9 40 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7963 EP 7970 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900010 ER PT J AU ROOD, RB NIELSEN, JE STOLARSKI, RS DOUGLASS, AR KAYE, JA ALLEN, DJ AF ROOD, RB NIELSEN, JE STOLARSKI, RS DOUGLASS, AR KAYE, JA ALLEN, DJ TI EPISODIC TOTAL OZONE MINIMA AND ASSOCIATED EFFECTS ON HETEROGENEOUS CHEMISTRY AND LOWER STRATOSPHERIC TRANSPORT SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID WINTERTIME ARCTIC STRATOSPHERE; AIRBORNE LIDAR OBSERVATIONS; NUMERICAL ADVECTION; POLAR VORTEX; PROFILE DATA; CLOUD EVENT; JANUARY 24; CONSERVATION; MODEL AB A description of the January 31, 1989, ozone minihole over Stavanger, Norway, is given on the basis of three-dimensional model simulations. This minihole is typical (though of large magnitude) of many transient events in the lower stratosphere that arise because of cyclonic-scale disturbances in the troposphere. The ozone reduction is a short-lived reversible dynamical event. However, through heterogeneous chemical processes there can be a significant transfer of chlorine from reservoir molecules to active radicals. This chemically perturbed air is defined as processed air, and it is found that a single event can produce enough processed air to reduce the HCI in the entire polar vortex. Chemical processing on clouds associated with transient events is shown to be a major source of processed air in the polar vortex in December before background temperatures are cold enough for more uniform heterogeneous conversion. In the model, intense cyclonic scales propagating close to the vortex edge and large planetary wave events (especially stratospheric warmings) are the major mechanisms of extra-vortex transport. Only a small amount of processed air is found outside of the polar vortex. The processed air is a strong function of longitude, and it is virtually excluded from the Pacific Basin. C1 APPL RES CORP, LANDOVER, MD USA. RP ROOD, RB (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 916, GREENBELT, MD 20771 USA. RI Allen, Dale/F-7168-2010; Douglass, Anne/D-4655-2012; Stolarski, Richard/B-8499-2013; Rood, Richard/C-5611-2008 OI Allen, Dale/0000-0003-3305-9669; Stolarski, Richard/0000-0001-8722-4012; Rood, Richard/0000-0002-2310-4262 NR 38 TC 43 Z9 43 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7979 EP 7996 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900012 ER PT J AU WILSON, JC STOLZENBURG, MR CLARK, WE LOEWENSTEIN, M FERRY, GV CHAN, KR KELLY, KK AF WILSON, JC STOLZENBURG, MR CLARK, WE LOEWENSTEIN, M FERRY, GV CHAN, KR KELLY, KK TI STRATOSPHERIC SULFATE AEROSOL IN AND NEAR THE NORTHERN-HEMISPHERE POLAR VORTEX - THE MORPHOLOGY OF THE SULFATE LAYER, MULTIMODAL SIZE DISTRIBUTIONS, AND THE EFFECT OF DENITRIFICATION SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CONDENSATION NUCLEI; EL-CHICHON; ANTARCTIC STRATOSPHERE; PARTICLE FORMATION; ACID CONDENSATION; CLOUD FORMATION; NITRIC-ACID; OZONE; TEMPERATURE; EXPEDITION AB Measurements were made of stratospheric sulfate aerosols using a passive cavity aerosol spectrometer and a condensation nucleus counter on a NASA ER-2 aircraft in the Airborne Arctic Stratospheric Experiment of 1989. The problems of representative and accurate sampling and particle evaporation were explicitly addressed in the design of the inlets and reduction of the data. The measurements suggest that the sulfate aerosol is bimodal in the polar vortex above the mass mixing ratio maximum in the sulfate layer. It appears that a nuclei mode of small, newly formed particles exists in this region. A stronger case is made for a nuclei mode in the upper few kilometers of the troposphere and in the lower few kilometers of the stratosphere. This mode is probably a global phenomenon occurring in all seasons. Comparison of denitrified and nondenitrified air suggests that denitrification removes some of the larger sulfate particles. C1 AEROSOL DYNAM INC, BERKELEY, CA USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NOAA, AERON LAB, BOULDER, CO 80303 USA. CALIF POLYTECH STATE UNIV SAN LUIS OBISPO, DEPT MECH ENGN, SAN LUIS OBISPO, CA 93407 USA. RP WILSON, JC (reprint author), UNIV DENVER, DEPT ENGN, DENVER, CO 80202 USA. NR 49 TC 33 Z9 33 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 7997 EP 8013 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900013 ER PT J AU DYE, JE BAUMGARDNER, D GANDRUD, BW KAWA, SR KELLY, KK LOEWENSTEIN, M FERRY, GV CHAN, KR GARY, BL AF DYE, JE BAUMGARDNER, D GANDRUD, BW KAWA, SR KELLY, KK LOEWENSTEIN, M FERRY, GV CHAN, KR GARY, BL TI PARTICLE-SIZE DISTRIBUTIONS IN ARCTIC POLAR STRATOSPHERIC CLOUDS, GROWTH AND FREEZING OF SULFURIC-ACID DROPLETS, AND IMPLICATIONS FOR CLOUD FORMATION SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE EXPERIMENT; AIRBORNE LIDAR OBSERVATIONS; NITRIC-ACID; CONDENSATION NUCLEI; BALLOON OBSERVATIONS; AEROSOL FORMATION; JANUARY 24; VORTEX; WATER; EVENT AB Particle size and volume measurements obtained with the forward scattering spectrometer probe (FSSP), model 300 during January and February 1989 in the Airborne Arctic Stratospheric Experiment are presented and used to study processes important in the formation and growth of polar stratospheric cloud (PSC) particles. Comparisons of the observations with expected sulfuric acid droplet deliquescence suggest that in the Arctic a major fraction of the sulfuric acid droplets remain liquid until temperatures at least as low as 193 K. Arguments are presented to suggest that homogeneous freezing of the sulfuric acid droplets might occur near 190 K and might play a role in the formation of PSC's. The first suggestion of nitric acid trihydrate (NAT) particles appears near saturation ratios of HNO3 with respect to NAT of 1 (about 195 K) as an enhancement of the large particles on the tail of the sulfuric acid droplet size distribution. The major increases in number and volume indicative of the main body of the NAT cloud are not seen in these Arctic investigations until 191 to 192 K, which corresponds to an apparent saturation ratio of HNO3 with respect to NAT of about 10, unlike the Antarctic where clouds were encountered at saturation ratios near 1. A decrease in the number of particles was observed in regions in which the airmass was denitrified, i.e. NOy, the sum of all reactive nitrogen species, was reduced. This was especially true for the larger particles on the upper tail of the sulfate size distribution. The loss of these largest particles supports the idea that denitrification may be the result of the preferential nucleation and growth of NAT on only the largest sulfate particles, which then sediment out of the airmass. C1 JET PROP LAB, PASADENA, CA 91109 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP DYE, JE (reprint author), NATL CTR ATMOSPHER RES, POB 3000, BOULDER, CO 80307 USA. RI Kawa, Stephan/E-9040-2012 NR 59 TC 210 Z9 210 U1 3 U2 17 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 8015 EP 8034 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900014 ER PT J AU PUESCHEL, RF FERRY, GV SNETSINGER, KG GOODMAN, J DYE, JE BAUMGARDNER, D GANDRUD, BW AF PUESCHEL, RF FERRY, GV SNETSINGER, KG GOODMAN, J DYE, JE BAUMGARDNER, D GANDRUD, BW TI A CASE OF TYPE-I POLAR STRATOSPHERIC CLOUD FORMATION BY HETEROGENEOUS NUCLEATION SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TOTAL REACTIVE NITROGEN; ANTARCTIC OZONE HOLE; NITRIC-ACID; JANUARY 24; ICE; AEROSOL; DEPLETION; NITRATE; HCL; CONDENSATION AB The NASA ER-2 aircraft flew on January 24, 1989, from Stavanger to Spitsbergen, Norway, at the 430-440 K potential temperature surface (19.2-19.8 km pressure altitude). Aerosols were sampled continuously by an optical particle counter (PMS-FSSP300) for concentration and size analyses, and during five 10-min intervals by four wire and one replicator impactor for concentration, size, composition, and phase analyses. During sampling, the air saturation of H2O with respect to ice changed from 20% to 100%. and of HNO3 with to nitric acid trihydrate (NAT) from subaturation to supersaturation. Data from both instruments indicate a condensation of hydrochloric acid and, later, nitric acid on the background aerosol particles as the ambient temperature decreases along the flight track. This heterogeneous nucleation mechanism generates type I polar stratospheric cloud particles of 10-fold enhanced optical depth, which could play a role in stratospheric ozone depletion. C1 SAN JOSE STATE UNIV, SAN JOSE, CA 95192 USA. NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. RP PUESCHEL, RF (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 39 TC 21 Z9 21 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 30 PY 1992 VL 97 IS D8 BP 8105 EP 8114 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY079 UT WOS:A1992HY07900023 ER PT J AU NESBITT, JA VINARCIK, EJ BARRETT, CA DOYCHAK, J AF NESBITT, JA VINARCIK, EJ BARRETT, CA DOYCHAK, J TI DIFFUSIONAL TRANSPORT AND PREDICTING OXIDATIVE FAILURE DURING CYCLIC OXIDATION OF BETA-NIAL ALLOYS SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article ID AL; PHASE AB Nickel aluminides (NiAl) containing 40-50 at.% Al and up to 0.1 at.% Zr have been studied following cyclic oxidation at 1200, 1300, 1350 and 1400-degrees-C. The selective oxidation of aluminum resulted in the formation of protective Al2O3 scales on each alloy composition at each temperature. However, repeated cycling eventually resulted in the gradual formation of less protective NiAl2O4. The appearance of the NiAl2O4, signaling the end of the protective scale-forming capability of the alloy, was related to the presence of gamma'-(Ni3Al) which formed as a result of the loss of aluminum from the sample. A simple methodology is presented to predict the protective life of beta-NiAl alloys. This method predicts the oxidative lifetime due to aluminum depletion when the aluminum concentration decreases to a critical concentration. The time interval preceding NiAl2O4 formation (i.e. the lifetime based on protective Al2O3 formation) and predicted lifetimes are compared and discussed. Use of the method to predict the maximum use temperature for NiAl-Zr alloys is also discussed. RP NESBITT, JA (reprint author), NASA,LEWIS RES CTR,MS 106-1,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 8 TC 29 Z9 29 U1 0 U2 6 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD MAY 30 PY 1992 VL 153 IS 1-2 BP 561 EP 566 DI 10.1016/0921-5093(92)90251-U PG 6 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA JC007 UT WOS:A1992JC00700032 ER PT J AU RAMSAY, DA DRACHMAN, DB DRACHMAN, RJ STANLEY, EF AF RAMSAY, DA DRACHMAN, DB DRACHMAN, RJ STANLEY, EF TI STABILIZATION OF ACETYLCHOLINE-RECEPTORS AT THE NEUROMUSCULAR SYNAPSE - THE ROLE OF THE NERVE SO BRAIN RESEARCH LA English DT Article DE ACETYLCHOLINE RECEPTOR; NEUROMUSCULAR JUNCTION; RECEPTOR STABILIZATION; RECEPTOR TURNOVER; PLASTICITY; RECEPTOR KINETICS ID SKELETAL-MUSCLE; ALPHA-BUNGAROTOXIN; RAT DIAPHRAGM; MYASTHENIC IMMUNOGLOBULIN; BETA-SUBUNIT; DEGRADATION; JUNCTIONS; MEMBRANE; TURNOVER; STABILITY AB The majority of acetylcholine receptors (AChRs) at innervated neuromuscular junctions (NMJs) are stable, with half-lives averaging about 11 days in rodent muscles. In addition to the stable AChRs, approximately 18% of AChRs at these innervated junctions are rapidly turned over (RTOs), with half lives of less than 24 h. We have postulated that RTOs may be precursors of stable AChRs, and that the motor nerve may influence their stabilization. This hypothesis was tested by: (i) labeling AChRs in mouse sternomastoid (SM) muscles with I-125-alpha-BuTx; (ii) denervating one SM muscle in each mouse, and (iii) following the fate of the labeled AChRs through a 5-day period when RTOs were either stabilized or degraded. The hypothesis predicts that denervation should preclude stabilization of RTOs, resulting in a deficit of stable AChRs in denervated muscles. The results showed a highly significant (P < 0.002) deficit of stable AChRs in denervated as compared with innervated muscles. Control experiments excluded the possibility that this deficit could be attributed to independent accelerated degradation of either RTOs or pre-existing stable AChRs. The observed deficit was quantitatively consistent with the deficit predicted by a mathematical model based on interruption of stabilization following denervation. We conclude that: (i) the observed deficit after denervation of NMJs is due to failure of stabilization of pre-existing RTOs; (ii) RTOs at normally innervated NMJs are precursors of stable AChRs; (iii) stabilization occurs after the insertion of AChRs at NMJs, and (iv) motor nerves play a key role in stabilization of RTOs. The concept of receptor stabilization has important implications for understanding the biology of the neuromuscular junction and post-synaptic plasticity. C1 JOHNS HOPKINS UNIV,SCH MED,DEPT NEUROL,600 N WOLFE ST,BALTIMORE,MD 21205. VICTORIA HOSP,DEPT NEUROPATHOL,LONDON N6A 4G5,ONTARIO,CANADA. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NIH,BETHESDA,MD 20892. FU NINDS NIH HHS [1R01 NS23719] NR 53 TC 14 Z9 14 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0006-8993 J9 BRAIN RES JI Brain Res. PD MAY 29 PY 1992 VL 581 IS 2 BP 198 EP 207 DI 10.1016/0006-8993(92)90709-I PG 10 WC Neurosciences SC Neurosciences & Neurology GA JB033 UT WOS:A1992JB03300003 PM 1393528 ER PT J AU KANIK, I TRAJMAR, S NICKEL, JC AF KANIK, I TRAJMAR, S NICKEL, JC TI TOTAL CROSS-SECTION MEASUREMENTS FOR ELECTRON-SCATTERING ON CH4 FROM 4 TO 300 EV SO CHEMICAL PHYSICS LETTERS LA English DT Article ID LOW-ENERGY ELECTRONS; ELASTIC-SCATTERING; METHANE; COLLISIONS; POSITRONS AB Total cross sections have been measured for electron scattering on CH4 in the 4-300 eV energy range utilizing a linear attenuation technique. The present results are compared with existing experimental data of other groups in this energy range. Generally, a good agreement with other experimental data is found except with those of Barbarito, Basta and Caliechio and Sueoka and Mori. The total electron scattering cross sections below 10 eV are inconsistent with available integral elastic scattering cross sections. It is suggested that the elastic data are in error and should be remeasured. C1 JET PROP LAB,PASADENA,CA 91109. UNIV CALIF RIVERSIDE,DEPT PHYS,RIVERSIDE,CA 92521. NR 29 TC 18 Z9 18 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 MAY 29 PY 1992 VL 193 IS 4 BP 281 EP 286 DI 10.1016/0009-2614(92)85668-Z PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA HZ328 UT WOS:A1992HZ32800013 ER PT J AU COLUSSI, AJ SANDER, SP FRIEDL, RR AF COLUSSI, AJ SANDER, SP FRIEDL, RR TI TEMPERATURE-DEPENDENCE AND MECHANISM OF THE REACTION BETWEEN O(3P) AND CHLORINE DIOXIDE SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID RATE CONSTANTS; KINETICS; CIO; NM AB Second-order rate constants for the decay of O(3P) in excess chlorine dioxide, k(II), were measured by flash photolysis-atomic resonance fluorescence as a function of total pressure (20-600 Torr argon) and temperature (248-312 K). It was found that (1) k(II) is pressure dependent with a value, k(b), that is nonzero at zero pressure and (2) both the third-order rate constant (dk(II)/d[M])[M] = 0 = k(o), and k(b) have negative temperature dependences. These results are consistent with an association reaction leading to an intermediate having two decomposition channels: O + OClO <--> ClO3* (1, 2); ClO3* + M --> ClO3 + M (3); ClO3* --> ClO + O2* (4), with E(o2) > E(o4). The measured k(o) values were used in conjunction with Troe's expression for unimolecular decomposition rates in the low-pressure limit to derive a critical energy for ClO3 of 10 700 cm-1, which leads to DELTA-H(f)(ClO3) = 51.9 +/- 5 kcal/mol. This is approximately 4 kcal/mol smaller than the value derived in our previous room temperature study of this reaction. C1 JET PROP LAB,PASADENA,CA 91109. RI Colussi, Agustin/C-6520-2008 NR 17 TC 34 Z9 34 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD MAY 28 PY 1992 VL 96 IS 11 BP 4442 EP 4445 DI 10.1021/j100190a058 PG 4 WC Chemistry, Physical SC Chemistry GA HX268 UT WOS:A1992HX26800058 ER PT J AU NICKEL, JC KANIK, I TRAJMAR, S IMRE, K AF NICKEL, JC KANIK, I TRAJMAR, S IMRE, K TI TOTAL CROSS-SECTION MEASUREMENTS FOR ELECTRON-SCATTERING ON H-2 AND N-2 FROM 4 TO 300 EV SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID MOLECULAR-HYDROGEN; HE; POSITRONS; CO2; N2 AB Total cross sections have been measured for electron scattering on H-2 and N2 in the 4-300 eV energy range utilizing a linear attenuation technique. The present results are compared with existing experimental data of other groups in this energy range where good agreement with other experimental data is found. C1 JET PROP LAB,PASADENA,CA 91109. RP NICKEL, JC (reprint author), UNIV CALIF RIVERSIDE,DEPT PHYS,RIVERSIDE,CA 92521, USA. NR 25 TC 20 Z9 20 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD MAY 28 PY 1992 VL 25 IS 10 BP 2427 EP 2431 DI 10.1088/0953-4075/25/10/020 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA HX066 UT WOS:A1992HX06600020 ER PT J AU BERTSCH, DL BRAZIER, KTS FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA KWOK, PW LIN, YC MATTOX, JR MAYERHASSELWANDER, HA VONMONTIGNY, C MICHELSON, PF NOLAN, PL PINKAU, K ROTHERMEL, H SCHNEID, EJ SOMMER, M SREEKUMAR, P THOMPSON, DJ AF BERTSCH, DL BRAZIER, KTS FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA KWOK, PW LIN, YC MATTOX, JR MAYERHASSELWANDER, HA VONMONTIGNY, C MICHELSON, PF NOLAN, PL PINKAU, K ROTHERMEL, H SCHNEID, EJ SOMMER, M SREEKUMAR, P THOMPSON, DJ TI PULSED HIGH-ENERGY GAMMA-RADIATION FROM GEMINGA (1E0630+178) SO NATURE LA English DT Article ID 1E 0630+178; PULSARS; TELESCOPE AB HALPERN and Holt 1 have recently reported the detection of coherent pulsations with a period of 237 ms from the soft X-ray source 1E0630 + 178, which lies in the error box of the gamma-ray source known as Geminga (2GC195 + 04). This observation provides compelling evidence that Geminga, an object whose nature has hitherto been mysterious, is an X-ray pulsar. Prompted by this discovery, we have searched the data from EGRET, the Energetic Gamma Ray Experiment Telescope on the Compton Gamma Ray Observatory, for a comparable signal in the gamma-radiation from this part of the sky. We now report the detection of pulsed gamma-rays, with energy > 50 MeV, from 1E0630 + 178, confirming the identification of Geminga with this X-ray source. The period derivative, (11.4 +/- 1.7) x 10(15) ss-1, suggests that Geminga is a nearby, isolated, rotating neutron star with a magnetic field of 1.6 x 10(12) gauss, a characteristic age of 3 x 10(5) yr and a spin-down energy loss rate of 3.5 x 10(34) erg s-1. C1 MAX PLANCK INST PHYS & ASTROPHYS,INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. STANFORD UNIV,DEPT PHYS,STANFORD,CA 94305. STANFORD UNIV,WW HANSEN EXPTL PHYS LAB,STANFORD,CA 94305. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RP BERTSCH, DL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CSC,COMPTON OBSERV SCI SUPPORT CTR,GREENBELT,MD 20771, USA. RI Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; Nolan, Patrick/A-5582-2009 OI Thompson, David/0000-0001-5217-9135; NR 19 TC 199 Z9 199 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD MAY 28 PY 1992 VL 357 IS 6376 BP 306 EP 307 DI 10.1038/357306a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HW132 UT WOS:A1992HW13200038 ER PT J AU ALBEE, AL ARVIDSON, RE PALLUCONI, FD AF ALBEE, AL ARVIDSON, RE PALLUCONI, FD TI MARS-OBSERVER MISSION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article AB The Mars Observer mission will extend the exploration and characterization of Mars by providing new and systematic measurements of the atmosphere, surface, and interior of the planet. These measurements will be made from a low-altitude polar orbiter over a period of 1 Martian year, permitting repetitive observations of the surface and of the seasonal variations of the atmosphere. The mission will be conducted in a manner that will provide new and valuable scientific data using a distributed data system that minimizes operational complexity and cost. C1 CALTECH,PASADENA,CA 91125. WASHINGTON UNIV,MCDONNELL CTR SPACE SCI,ST LOUIS,MO 63130. JET PROP LAB,PASADENA,CA 91109. NR 14 TC 12 Z9 12 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAY 25 PY 1992 VL 97 IS E5 BP 7665 EP 7680 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU049 UT WOS:A1992KU04900002 ER PT J AU BOYNTON, WV TROMBKA, JI FELDMAN, WC ARNOLD, JR ENGLERT, PAJ METZGER, AE REEDY, RC SQUYRES, SW WANKE, H BAILEY, SH BRUCKNER, J CALLAS, JL DRAKE, DM DUKE, P EVANS, LG HAINES, EL MCCLOSKEY, FC MILLS, H SHINOHARA, C STARR, R AF BOYNTON, WV TROMBKA, JI FELDMAN, WC ARNOLD, JR ENGLERT, PAJ METZGER, AE REEDY, RC SQUYRES, SW WANKE, H BAILEY, SH BRUCKNER, J CALLAS, JL DRAKE, DM DUKE, P EVANS, LG HAINES, EL MCCLOSKEY, FC MILLS, H SHINOHARA, C STARR, R TI SCIENCE APPLICATIONS OF THE MARS-OBSERVER GAMMA-RAY SPECTROMETER SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GERMANIUM DETECTORS; PLANETARY SURFACES; RADIATION-DAMAGE; SPECTROSCOPY; LUNAR; SPECTRA; H2O; CO2 AB The Mars Observer gamma ray spectrometer will return data related to the elemental composition of Mars. The instrument has both a gamma ray spectrometer and several neutron detectors. The gamma ray spectrometer will return a spectrum nominally every 20 s from Mars permitting a map of the elemental abundances to be made. The gamma rays are emitted from nuclei involved in radioactive decay, from nuclei formed by capture of a thermal neutron, and from nuclei put in an excited state by a fast-neutron interaction. The gamma rays come from an average depth of the order of a few tens of centimeters. The spectrum will show sharp emission lines whose intensity determines the concentration of the element and whose energy identifies the element. The neutron detectors, using the fact that the orbital velocity of the Mars Observer spacecraft is similar to the velocity of thermal neutrons, determine both the thermal and epithermal neutron flux. These parameters are particularly sensitive to the concentration of hydrogen in the upper meter of the surface. By combining the results from both techniques it is possible to map the depth dependence of hydrogen in the upper meter as well. These data permit a variety of Martian geoscience problems to be addressed including the crust and mantle composition, weathering processes, volcanism, and the volatile reservoirs and processes. In addition, the instrument is also sensitive to gamma ray and particle fluxes from non-Martian sources and will be able to address problems of astrophysical interest including gamma ray bursts, the extragalactic background, and solar processes. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. UNIV CALIF SAN DIEGO,DEPT CHEM,LA JOLLA,CA 92093. SAN JOSE STATE UNIV,DEPT CHEM,SAN JOSE,CA 95192. JET PROP LAB,PASADENA,CA 91109. CORNELL UNIV,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853. MAX PLANCK INST CHEM,W-6500 MAINZ,GERMANY. SUNRISE RES INC,EUGENE,OR. NR 50 TC 38 Z9 38 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAY 25 PY 1992 VL 97 IS E5 BP 7681 EP 7698 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU049 UT WOS:A1992KU04900003 ER PT J AU CHRISTENSEN, PR ANDERSON, DL CHASE, SC CLARK, RN KIEFFER, HH MALIN, MC PEARL, JC CARPENTER, J BANDIERA, N BROWN, FG SILVERMAN, S AF CHRISTENSEN, PR ANDERSON, DL CHASE, SC CLARK, RN KIEFFER, HH MALIN, MC PEARL, JC CARPENTER, J BANDIERA, N BROWN, FG SILVERMAN, S TI THERMAL EMISSION SPECTROMETER EXPERIMENT - MARS-OBSERVER MISSION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID INFRARED MULTISPECTRAL SCANNER; RESIDUAL CO2 FROST; NORTH POLAR-CAP; MARTIAN ATMOSPHERE; COMPOSITIONAL IMPLICATIONS; PHYSICAL-PROPERTIES; IGNEOUS ROCKS; DEATH-VALLEY; SURFACE; DUST AB Thermal infrared spectral measurements will be made of the surface and atmosphere of Mars by the thermal emission spectrometer (TES) on board Mars Observer. By using these observations the composition of the surface rocks, minerals, and condensates will be determined and mapped. In addition, the composition and distribution of atmospheric dust and condensate clouds, together with temperature profiles of the CO2 atmosphere, will be determined. Broadband solar reflectance and thermal emittance measurements will also he made to determine the energy balance in the polar regions and to map the thermophysical properties of the surface. The specific science objectives of this investigation are to determine (1) the composition and distribution of surface materials, (2) the composition, particle size, and spatial and temporal distribution of suspended dust, (3) the location, temperature, height, and water abundance of H2O clouds. (4) the composition, seasonal behavior, total energy balance, and physical properties of the polar caps, and (5) the particle size distribution of rocks and fines on the surface. The instrument consists of three subsections: a Michelson interferometer, a solar reflectance sensor. and a broadband radiance sensor. The spectrometer covers the wavelength range from 6 to 50 mum (approximately 1600-200 cm-1) with nominal 5 and 10 cm-1 spectral resolution. The solar reflectance band extends from 0.3 to 2.7 mum: the broadband radiance channel extends from 5.5 to 100 mum. There are six 8.3-mrad fields of view for each sensor arranged in a 3 x 2 array, each with 3-km resolution at the nadir. Uncooled deuterated triglycine sulphate (DTGS) pyroelectic detectors provide a signal-to-noise ratio (SNR) of over 500 at 10 mum for daytime spectral observations at a surface temperature of 270 K. The SNR of the albedo and thermal bolometers will be approximately 2000 at the peak signal levels expected. The instrument is 23.6 x 35.5 x 40.0 cm, with a mass of 14.4 kg and an average power consumption of 14.5 W. The approach will be to measure the spectral properties of thermal energy emitted from the surface and atmosphere. Emission phase angle studies and day-night observations will be used to separate the spectral character of the surface and atmosphere. The distinctive thermal infrared spectral features present in minerals, rocks, and condensates will be used to determine the mineralogic and petrologic character of the surface and to identify and study aerosols and volatiles in the atmosphere. C1 ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. SANTA BARBARA RES CTR,GOLETA,CA. US GEOL SURVEY,GEOPHYS BRANCH,DENVER,CO 80225. US GEOL SURVEY,FLAGSTAFF,AZ 86001. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 102 TC 229 Z9 231 U1 5 U2 15 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAY 25 PY 1992 VL 97 IS E5 BP 7719 EP 7734 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU049 UT WOS:A1992KU04900005 ER PT J AU MCCLEESE, DJ HASKINS, RD SCHOFIELD, JT ZUREK, RW LEOVY, CB PAIGE, DA TAYLOR, FW AF MCCLEESE, DJ HASKINS, RD SCHOFIELD, JT ZUREK, RW LEOVY, CB PAIGE, DA TAYLOR, FW TI ATMOSPHERE AND CLIMATE STUDIES OF MARS USING THE MARS-OBSERVER PRESSURE MODULATOR INFRARED RADIOMETER SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GLOBAL DUST STORMS; RESIDUAL CO2 FROST; MARTIAN ATMOSPHERE; MIDDLE ATMOSPHERE; WATER-VAPOR; GENERAL-CIRCULATION; SEASONAL RESERVOIRS; MEAN CIRCULATION; THERMAL INERTIA; POLAR CAPS AB Studies of the climate and atmosphere of Mars are limited at present by a lack of meteorological data having systematic global coverage with good horizontal and vertical resolution. The Mars Observer spacecraft in a low, nearly circular, polar orbit will provide an excellent platform for acquiring the data needed to advance significantly our understanding of the Martian atmosphere and its remarkable variability. The Mars Observer pressure modulator infrared radiometer (PMIRR) is a nine-channel limb and nadir scanning atmospheric sounder which will observe the atmosphere of Mars globally from 0 to 80 km for a full Martian year. PMIRR employs narrow-band radiometric channels and two pressure modulation cells to measure atmospheric and surface emission in the thermal infrared: a visible channel (0.39-4.7 mum) is used to measure solar radiation reflected from the atmosphere and surface. Vertical profiles of atmospheric temperature, the infrared extinction of dust suspended in the atmosphere, atmospheric water vapor, and condensate hazes will be retrieved from infrared measurements having a vertical resolution of 5 km, which is half an atmospheric scale height. PMIRR infrared and visible measurements will be combined to determine the radiative balance of the polar regions, where a sizeable fraction of the global atmospheric mass annually condenses onto and sublimes from the surface. Derived meteorological fields, including diabatic heating and cooling and the vertical variation of horizontal winds, will be computed from the globally mapped fields retrieved from PMIRR data. Analyses of these observed and derived fields will address many key questions regarding the atmosphere and climate of Mars. C1 JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. UNIV CALIF LOS ANGELES,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. UNIV OXFORD,DEPT ATMOSPHER OCEAN & PLANETARY PHYS,OXFORD,ENGLAND. NR 118 TC 28 Z9 28 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAY 25 PY 1992 VL 97 IS E5 BP 7735 EP 7757 PG 23 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU049 UT WOS:A1992KU04900006 ER PT J AU TYLER, GL BALMINO, G HINSON, DP SJOGREN, WL SMITH, DE WOO, R ASMAR, SW CONNALLY, MJ HAMILTON, CL SIMPSON, RA AF TYLER, GL BALMINO, G HINSON, DP SJOGREN, WL SMITH, DE WOO, R ASMAR, SW CONNALLY, MJ HAMILTON, CL SIMPSON, RA TI RADIO SCIENCE INVESTIGATIONS WITH MARS-OBSERVER SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MARTIAN ATMOSPHERE; DUST STORMS; OCCULTATION MEASUREMENTS; VOYAGER MEASUREMENTS; HELIUM ABUNDANCE; TOPOGRAPHY; INERTIA; VENUS; IONOSPHERE; GRAVITY AB Mars Observer radio science investigations focus on two major areas of study: the gravity field and the atmosphere of Mars. Measurement accuracies expressed as an equivalent spacecraft velocity are expected to be of the order of 100 mum/s (for both types of investigations) from use of an improved radio transponder for two-way spacecraft tracking and a highly stable on-board oscillator for atmospheric occultation measurements, Planned gravity investigations include a combination of classical and modern elements. A spherical harmonic (or equivalent) field model of degree and order in the range 30-50 will be obtained, while interpretation will be in terms of internal stress and density models for the planet, using the topography to be obtained from the Mars Observer laser altimeter. Atmospheric investigations will emphasize precision measurement of the thermal structure and dynamics in the polar regions, which are regularly accessible as a result of the highly inclined orbit. Studies based on the measurements will include polar processes, cycling of the atmosphere between the poles, traveling baroclinic disturbances, small-scale waves and turbulence, the planetary boundary layer, and (possibly) the variability and altitude of the ionosphere. As the radio occultation is insensitive to dust in the atmosphere per se and measures only the resulting change in thermal structure, it is expected that the radio technique can contribute to understanding of dust storm phenomena. Mutual observations of the atmosphere by means of radio occultation and by the pressure modulator infrared radiometer and the thermal emission spectrometer are expected to strengthen the reliability and accuracy of all three investigations. C1 STANFORD UNIV,STANFORD,CA 94305. GRP RECH GEODESIE SPATIALES,TOULOUSE,FRANCE. JET PROP LAB,PASADENA,CA 91109. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 68 TC 51 Z9 53 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAY 25 PY 1992 VL 97 IS E5 BP 7759 EP 7779 DI 10.1029/92JE00513 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU049 UT WOS:A1992KU04900007 ER PT J AU ZUBER, MT SMITH, DE SOLOMON, SC MUHLEMAN, DO HEAD, JW GARVIN, JB ABSHIRE, JB BUFTON, JL AF ZUBER, MT SMITH, DE SOLOMON, SC MUHLEMAN, DO HEAD, JW GARVIN, JB ABSHIRE, JB BUFTON, JL TI THE MARS-OBSERVER LASER ALTIMETER INVESTIGATION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID RADIO OCCULTATION MEASUREMENTS; MARTIAN TOPOGRAPHY; GENERAL-CIRCULATION; TERRESTRIAL PLANETS; LITHOSPHERIC STRESS; VISCOUS RELAXATION; SURFACE PROPERTIES; MIDDLE ATMOSPHERE; THARSIS PROVINCE; IMPACT BASINS AB The primary objective of the Mars Observer laser altimeter (MOLA) investigation is to determine globally the topography of Mars at a level suitable for addressing problems in geology and geophysics. Secondary objectives are to characterize the 1064-nm wavelength surface reflectivity of Mars to contribute to analyses of global surface mineralogy and seasonal albedo changes, to assist in addressing problems in atmospheric circulation, and to provide geodetic control and topographic context for the assessment of possible future Mars landing sites. The principal components of MOLA are a diode-pumped, neodymium-doped yttrium aluminum garnet laser transmitter that emits 1064-nm wavelength laser pulses, a 0.5-m-diameter telescope, a silicon avalanche photodiode detector, and a time interval unit with 10-ns resolution. MOLA will provide measurements of the topography of Mars within approximately 160-m footprints and a center-to-center along-track footprint spacing of 300 m along the Mars Observer subspacecraft ground track. The elevation measurements will be quantized with 1.5 m vertical resolution before correction for orbit- and pointing-induced errors. MOLA profiles will be assembled into a global 0.2-degrees x 0.2-degrees grid that will be referenced to Mars' center of mass with an absolute accuracy of approximately 30 m. Other data products will include a global grid of topographic gradients, corrected individual profiles, and a global 0.2-degrees x 0.2-degrees grid of 1064-nm surface reflectivity. C1 JOHNS HOPKINS UNIV,DEPT EARTH & PLANETARY SCI,BALTIMORE,MD 21218. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. BROWN UNIV,DIV GEOL SCI,PROVIDENCE,RI 02912. NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. RI Abshire, James/I-2800-2013 NR 107 TC 286 Z9 287 U1 2 U2 12 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAY 25 PY 1992 VL 97 IS E5 BP 7781 EP 7797 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU049 UT WOS:A1992KU04900008 ER PT J AU ACUNA, MH CONNERNEY, JEP WASILEWSKI, P LIN, RP ANDERSON, KA CARLSON, CW MCFADDEN, J CURTIS, DW REME, H CROS, A MEDALE, JL SAUVAUD, JA DUSTON, C BAUER, SJ CLOUTIER, P MAYHEW, M NESS, NF AF ACUNA, MH CONNERNEY, JEP WASILEWSKI, P LIN, RP ANDERSON, KA CARLSON, CW MCFADDEN, J CURTIS, DW REME, H CROS, A MEDALE, JL SAUVAUD, JA DUSTON, C BAUER, SJ CLOUTIER, P MAYHEW, M NESS, NF TI MARS-OBSERVER MAGNETIC-FIELDS INVESTIGATION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MARTIAN MAGNETOSPHERE; MAGSAT; MODEL; ANOMALIES; ELECTRON; GRAVITY; EARTH AB The Mars Observer magnetic fields investigation will provide fast vector measurements of the Martian magnetic field over a wide dynamic range. The fundamental objectives of this investigation are (1) to establish the nature of the magnetic field of Mars, (2) to develop appropriate models for its representation, which take into account the internal sources of magnetism and the effects of the interaction with the solar wind, and (3) to map the Martian crustal remanent field to a resolution consistent with the Mars Observer orbit altitude and ground track separation. The basic instrumentation complement implemented for this mission is a synergistic combination of a dual, triaxial, flux gate magnetometer system and an electron reflectometer with sensors mounted on a spacecraft boom. The dual magnetometer system allows the real-time estimation and correction of spacecraft-generated fields, while the electron reflectometer provides remote magnetic field sensing capabilities. These instruments have an extensive spaceflight heritage, and similar versions of the same have been flown in numerous missions like Vovager, Magsat, International Solar Polar mission (ISPM), Giotto, Active Magnetospheric Particle Tracer Explorers, and Global Geospace Science (GGS). Depending on the telemetry rate supported, a minimum of 2-16 vector samples per second will be acquired. The instrument is microprocessor controlled, can be partially reprogrammed in flight, and supports the packet telemetry protocol implemented for Mars Observer. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. CTR ETUD SPATIALE RAYONNEMENTS,TOULOUSE,FRANCE. GRAZ UNIV,A-8010 GRAZ,AUSTRIA. AUSTRIAN ACAD SCI,SPACE RES INST,GRAZ,AUSTRIA. RICE UNIV,DEPT SPACE SCI,HOUSTON,TX 77251. NATL SCI FDN,WASHINGTON,DC 20550. UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716. RI connerney, john/I-5127-2013 NR 54 TC 84 Z9 86 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAY 25 PY 1992 VL 97 IS E5 BP 7799 EP 7814 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA KU049 UT WOS:A1992KU04900009 ER PT J AU ROSS, MD CHIMENTO, T DOSHAY, D CHENG, R AF ROSS, MD CHIMENTO, T DOSHAY, D CHENG, R TI COMPUTER-ASSISTED 3-DIMENSIONAL RECONSTRUCTION AND SIMULATIONS OF VESTIBULAR MACULAR NEURAL CONNECTIVITIES SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article ID GENERATED IMAGERY; 3-D COMPONENTS; HAIR-CELLS; ORGANIZATION; NETWORK; BUNDLES; CALCIUM; SPINES; RAT C1 STERLING SOFTWARE,PALO ALTO,CA 94303. RP ROSS, MD (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 39 TC 8 Z9 9 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD MAY 22 PY 1992 VL 656 BP 75 EP 91 DI 10.1111/j.1749-6632.1992.tb25201.x PG 17 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM221 UT WOS:A1992JM22100006 PM 1350896 ER PT J AU TOMKO, DL PAIGE, GD AF TOMKO, DL PAIGE, GD TI LINEAR VESTIBULOOCULAR REFLEX DURING MOTION ALONG AXES BETWEEN NASOOCCIPITAL AND INTERAURAL SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article ID EYE-MOVEMENT RESPONSES; SQUIRREL-MONKEY; HEAD MOTION C1 STANFORD MED CTR,DIV OTOLARYNGOL HEAD & NECK SURG,STANFORD,CA 94305. UNIV ROCHESTER,DEPT NEUROL,ROCHESTER,NY 14642. RP TOMKO, DL (reprint author), NASA,AMES RES CTR,DIV LIFE SCI,VESTIBULAR RES FACIL,MOFFETT FIELD,CA 94035, USA. NR 5 TC 23 Z9 23 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD MAY 22 PY 1992 VL 656 BP 233 EP 241 DI 10.1111/j.1749-6632.1992.tb25212.x PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM221 UT WOS:A1992JM22100017 PM 1599146 ER PT J AU COHEN, MM AF COHEN, MM TI PERCEPTION AND ACTION IN ALTERED GRAVITY SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article RP COHEN, MM (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 13 TC 5 Z9 5 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD MAY 22 PY 1992 VL 656 BP 354 EP 362 DI 10.1111/j.1749-6632.1992.tb25221.x PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM221 UT WOS:A1992JM22100026 PM 1599155 ER PT J AU BLOOMBERG, JJ RESCHKE, MF HUEBNER, WP PETERS, BT AF BLOOMBERG, JJ RESCHKE, MF HUEBNER, WP PETERS, BT TI THE EFFECTS OF TARGET DISTANCE ON EYE AND HEAD MOVEMENT DURING LOCOMOTION SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article ID SQUIRREL-MONKEY; LINEAR MOTION; RESPONSES; WEIGHTLESSNESS; REFLEX; HUMANS; TASKS C1 KRUG LIFE SCI, HOUSTON, TX 77058 USA. RP BLOOMBERG, JJ (reprint author), NASA, AMES RES CTR, SPACE BIOMED RES INST, MAIL CODE SD5, MOFFETT FIELD, CA 94035 USA. NR 19 TC 1 Z9 1 U1 0 U2 2 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 USA SN 0077-8923 J9 ANN NY ACAD SCI JI Ann.NY Acad.Sci. PD MAY 22 PY 1992 VL 656 BP 699 EP 707 PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM221 UT WOS:A1992JM22100052 ER PT J AU PALOSKI, WH RESCHKE, MF BLACK, FO DOXEY, DD HARM, DL AF PALOSKI, WH RESCHKE, MF BLACK, FO DOXEY, DD HARM, DL TI RECOVERY OF POSTURAL EQUILIBRIUM CONTROL FOLLOWING SPACEFLIGHT SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article ID WEIGHTLESSNESS C1 GOOD SAMARITAN HOSP,RS DOW NEUROL SCI INST,PORTLAND,OR 97210. NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. RP PALOSKI, WH (reprint author), KRUG LIFE SCI INC,NEUROSCI LAB,1290 HERCULES,SUITE 120,HOUSTON,TX 77058, USA. FU NIDCD NIH HHS [DC-00205] NR 13 TC 60 Z9 61 U1 1 U2 1 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD MAY 22 PY 1992 VL 656 BP 747 EP 754 DI 10.1111/j.1749-6632.1992.tb25253.x PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM221 UT WOS:A1992JM22100058 PM 1599180 ER PT J AU NEMIRE, K COHEN, MM AF NEMIRE, K COHEN, MM TI OPTICAL AND SOMATESTHETIC BIASES OF POSTURAL ORIENTATION IN THE PITCH DIMENSION SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article RP NEMIRE, K (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD MAY 22 PY 1992 VL 656 BP 871 EP 873 DI 10.1111/j.1749-6632.1992.tb25279.x PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM221 UT WOS:A1992JM22100084 PM 1599205 ER PT J AU DAUNTON, NG CHRISTENSEN, CA AF DAUNTON, NG CHRISTENSEN, CA TI ANTAGONISTIC OTOLITH-VISUAL UNITS IN CAT VESTIBULAR NUCLEI SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article ID OPTOKINETIC STIMULATION C1 VASSAR COLL,DEPT PSYCHOL,POUGHKEEPSIE,NY 12601. RP DAUNTON, NG (reprint author), NASA,DIV LIFE SCI,MAIL STOP 261-3,MOFFETT FIELD,CA 94035, USA. NR 3 TC 1 Z9 2 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD MAY 22 PY 1992 VL 656 BP 924 EP 926 DI 10.1111/j.1749-6632.1992.tb25296.x PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA JM221 UT WOS:A1992JM22100101 PM 1599223 ER PT J AU KELLER, JW COPLAN, MA AF KELLER, JW COPLAN, MA TI ELECTRON-ENERGY LOSS SPECTROSCOPY OF C-60 SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CARBON; C-60 AB The electron energy loss spectrum of C60 in the gas phase from 1 to 30 eV is presented. The spectrum is similar to spectra of the solid, with shifts in the mutually observed bands seen only for the previously identified plasmon features. These results confirm this identification as well as provide an indirect measurement of the relative absorption cross section over this region. Results from large angle scattering measurements provide the first evidence of multipole plasmons in C60. C1 UNIV MARYLAND,INST PHYS & TECHNOL,COLLEGE PK,MD 20742. RP KELLER, JW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. RI Keller, John/I-5097-2013 NR 24 TC 91 Z9 92 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 MAY 22 PY 1992 VL 193 IS 1-3 BP 89 EP 92 DI 10.1016/0009-2614(92)85687-6 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA HW683 UT WOS:A1992HW68300014 ER PT J AU AHMADJIAN, M JENNINGS, DE MUMMA, MJ ESPENAK, F RICE, CJ RUSSELL, RW GREEN, BD AF AHMADJIAN, M JENNINGS, DE MUMMA, MJ ESPENAK, F RICE, CJ RUSSELL, RW GREEN, BD TI INFRARED SPECTRAL MEASUREMENT OF SPACE-SHUTTLE GLOW SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID VEHICLE GLOW; SATELLITE AB The U.S. Air Force and NASA successfully conducted infrared spectral measurements of the space shuttle glow during STS-39. Preliminary analysis indicates that NO, NO+, OH, and CO produce infrared glow during quiescent orbiter conditions. During orbiter thruster firings the glow intensities in the infrared are enhanced by factors of 10X to 100X with significant changes in spectral distribution. These measurements were obtained with the Spacecraft Kinetic Infrared Test (SKIRT) payload which included a cryogenic infrared circular variable filter infrared spectrometer covering the 0.7 to 5.4-mu-m wavelength region. Approximately 14,000 spectra of shuttle glow, airglow, aurora, and the orbiter environment were obtained during the eight day mission. The STS-39 Space Shuttle Discovery was launched from the NASA Kennedy Space Center on 28 April 1991 into a 57 deg inclination circular orbit at an altitude of 260-km. C1 PHYS SCI INC,ANDOVER,MA 01810. AEROSPACE CORP,LOS ANGELES,CA 90009. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP AHMADJIAN, M (reprint author), PHILLIPS LAB,GEOPHYS DIRECTORATE,BEDFORD,MA 01731, USA. RI Jennings, Donald/D-7978-2012; mumma, michael/I-2764-2013 NR 13 TC 17 Z9 17 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 22 PY 1992 VL 19 IS 10 BP 989 EP 992 DI 10.1029/92GL00051 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HW344 UT WOS:A1992HW34400009 ER PT J AU BILLS, BG AF BILLS, BG TI VENUS - SATELLITE ORBITAL DECAY, EPHEMERAL RING FORMATION, AND SUBSEQUENT CRATER PRODUCTION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TIDAL EVOLUTION; PLANETARY RINGS; NEPTUNE; PLANETESIMALS; STABILITY; ROTATION; BREAKUP; FIELD AB The remarkable state of preservation of Venus impact craters may reflect their recent origin from a circumplanetary source, rather than a recent decline in resurfacing efficiency. Many of the craters observed on Venus may have been produced by impacts of particles on tidally decaying, high inclination orbits about the planet, rather than asteroidal or cometary debris on heliocentric orbits. A single satellite with radius of 100-200 km, and initial orbital distance of 15-20 times the radius of Venus could have been the original source for all of the impacting material. Over a fairly wide range of initial conditions and tidal evolution models, the transfer of angular momentum from the satellite orbit to the planetary spin leads to a situation in which the satellite passes inside the Roche limit at high inclination to the equator of Venus. After the satellite is tidally disrupted, the fragments quickly spread out over the orbital path, and differential precession forms a partial shell of material. Subsequent collisional damping of relative inclinations collapses the particles into a flat ring, with one of three possible stable orientations; prograde equatorial, retrograde equatorial, or perpendicular to the equatorial plane. Rapid radial inflow accompanies collapse into either equatorial ring. Initial inclinations greater than 30-degrees at the time of disruption will lead to impact onto the surface during ring formation. Fragmentation reaches a steady state when the largest remaining particles have radii of 10-20 km. Bilateral symmetry of ejecta patterns reflect grazing impacts. RP BILLS, BG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,CODE 921,GREENBELT,MD 20771, USA. RI Bills, Bruce/C-1156-2008 NR 43 TC 3 Z9 3 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 22 PY 1992 VL 19 IS 10 BP 1025 EP 1028 DI 10.1029/92GL01067 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HW344 UT WOS:A1992HW34400018 ER PT J AU THOMPSON, AM AF THOMPSON, AM TI THE OXIDIZING CAPACITY OF THE EARTHS ATMOSPHERE - PROBABLE PAST AND FUTURE CHANGES SO SCIENCE LA English DT Article ID ACID DEPOSITION MODEL; TROPOSPHERIC OZONE PRODUCTION; CLIMATE CHANGE; HYDROGEN-PEROXIDE; SULFUR-DIOXIDE; SURFACE OZONE; METHANE; CHEMISTRY; OXIDANTS; MECHANISMS AB The principal oxidants in the lower atmosphere are ozone (O3) and two by-products of O3 photodissociation, the hydroxyl radical (OH) and hydrogen peroxide (H2O2). A number of critical atmospheric chemical problems depend on the earth's "oxidizing capacity," which is essentially the global burden of these oxidants. There is limited direct evidence for changes in the earth's oxidizing capacity since recent preindustrial times when, because of industrial and population growth, increasing amounts of O3 precursor trace gases (carbon monoxide, nitrogen oxides, and hydrocarbons) have been released into the atmosphere. The concentrations of O3 and possibly H2O2 have increased over large regions. Models predict that tropospheric O3 will increase approximately 0.3 to 1% per year over the next 50 years with both positive and negative trends possible for OH and H2O2. Models and the observational network for oxidants are improving, but validation of global models is still at an early stage. RP THOMPSON, AM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RI Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 121 TC 496 Z9 519 U1 6 U2 104 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 MAY 22 PY 1992 VL 256 IS 5060 BP 1157 EP 1165 DI 10.1126/science.256.5060.1157 PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HV192 UT WOS:A1992HV19200024 PM 1317061 ER PT J AU SEARS, DWG LU, J BENOIT, PH DEHART, JM LOFGREN, GE AF SEARS, DWG LU, J BENOIT, PH DEHART, JM LOFGREN, GE TI A COMPOSITIONAL CLASSIFICATION SCHEME FOR METEORITIC CHONDRULES SO NATURE LA English DT Article ID UNEQUILIBRATED ORDINARY CHONDRITES; CONDENSATION; ABUNDANCES; PETROLOGY; ORIGIN AB A taxonomic scheme is proposed for the main component of the primitive chondrite meteorites-the chondrules. The scheme provides insight into the variety of chondrules originally produced in the primordial solar nebula, and the effects on them of secondary processes on meteorite parent bodies. It may also contribute to understanding the origin of compositional diversity in the chondrites. C1 NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP SEARS, DWG (reprint author), UNIV ARKANSAS, COSMOCHEM GRP, FAYETTEVILLE, AR 72701 USA. NR 35 TC 42 Z9 43 U1 0 U2 3 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 J9 NATURE JI Nature PD MAY 21 PY 1992 VL 357 IS 6375 BP 207 EP 210 DI 10.1038/357207a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HV195 UT WOS:A1992HV19500044 ER PT J AU HALPERN, JP HOLT, SS AF HALPERN, JP HOLT, SS TI DISCOVERY OF SOFT-X-RAY PULSATIONS FROM THE GAMMA-RAY SOURCE GEMINGA SO NATURE LA English DT Article ID 1E 0630+178; PERIOD; PULSAR AB THE nature of the gamma-ray source 'Geminga' (2CG195 + 04) is a problem of considerable importance in high-energy astrophysics. First discovered in 1972 by the SAS-2 satellite 1, Geminga emits virtually all its power at energies above 50 MeV, and at energies above 100 MeV is the second brightest source in the gamma-ray sky survey made by the Cos-B satellite 2. It eluded identification at all other wavelengths until the Einstein Observatory found an unusual soft X-ray source, 1E0630 + 178, in its error box 3. This source also has a claimed twenty-fifth magnitude optical counterpart 4-6. This distinctive set of properties is reminiscent of the Vela pulsar, except for the absence of radio emission 7 or a synchrotron nebula 3. We have made a more sensitive soft X-ray observation of the Geminga field using Rosat, and have detected coherent pulsations from 1E0630 + 178 at a period of 0.237 s. This result confirms suggestions 3-6,8,9 that Geminga is, like Vela, a gamma-ray pulsar. We speculate that Geminga is somewhat the older of the two. With this discovery we consider the mystery of Geminga largely solved. C1 NASA,GODDARD SPACE FLIGHT CTR,SPACE SCI,GREENBELT,MD 20771. RP HALPERN, JP (reprint author), COLUMBIA UNIV,COLUMBIA ASTROPHYS LAB,538 W 120TH ST,NEW YORK,NY 10027, USA. NR 20 TC 246 Z9 246 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD MAY 21 PY 1992 VL 357 IS 6375 BP 222 EP 224 DI 10.1038/357222a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HV195 UT WOS:A1992HV19500047 ER PT J AU CUCINOTTA, FA TOWNSEND, LW WILSON, JW AF CUCINOTTA, FA TOWNSEND, LW WILSON, JW TI PRODUCTION OF H-3 AT LARGE MOMENTUM IN ALPHA-C-12 COLLISIONS AT 2A GEV SO PHYSICS LETTERS B LA English DT Article ID DISTRIBUTIONS; FRAGMENTATION; ENERGIES; SCATTERING; NUCLEI AB Calculations of the longitudinal and transverse momentum distributions for H-3 production at large momentum in alpha-C-12 collisions near 2 A GeV are compared to experiment. Triton exchange and final-state interactions are shown to represent large corrections to the impulse approximation for proton knockout. A method for calculating interference effects for inelastic fragmentation is discussed. Good agreement with experiment is found using a phenomenological overlap function for H-3-p successful in describing H-3 production in pion-induced reactions. Comparisons to momentum distributions obtained through (p, 2p) and (e, ep) reactions on He-4 are made. RP CUCINOTTA, FA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 22 TC 7 Z9 7 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-2693 J9 PHYS LETT B JI Phys. Lett. B PD MAY 21 PY 1992 VL 282 IS 1-2 BP 1 EP 6 DI 10.1016/0370-2693(92)90469-K PG 6 WC Astronomy & Astrophysics; Physics, Nuclear; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA HX882 UT WOS:A1992HX88200001 PM 11537626 ER PT J AU WILLIAMS, MD AF WILLIAMS, MD TI LASER POWER BEAMS OBTAINED BY THE DYNAMIC SELECTION OF EMITTING ELEMENTS IN AN ARRAY SO APPLIED OPTICS LA English DT Article DE LASERS; LASER DIODES; COHERENCE; QUASICOHERENCE; ARRAYS; FAST FOURIER TRANSFORMS; BEAM STEERING; FAR FIELD; POWER TRANSMISSION; ADAPTIVE OPTICS AB A method for partially correcting the spatial coherence of an array of laser beams is described. The method trades far-field intensity for simplistic implementation and array lifetime extension, resulting in a quasicoherent array with features of adaptive optics. An algorithm for implementing the method is described and feasible options for improvement are presented. A computer experiment used the algorithm and fast Fourier transforms to calculate typical far-field intensity distributions of such arrays. The far-field distributions illustrate beam power concentration, beam steering, and (indirectly) extended lifetime of the array. RP WILLIAMS, MD (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23669, USA. NR 5 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAY 20 PY 1992 VL 31 IS 15 BP 2738 EP 2742 PG 5 WC Optics SC Optics GA HU712 UT WOS:A1992HU71200012 PM 20725202 ER PT J AU LOCK, JA SEASHOLTZ, RG JOHN, WT AF LOCK, JA SEASHOLTZ, RG JOHN, WT TI RAYLEIGH-BRILLOUIN SCATTERING TO DETERMINE ONE-DIMENSIONAL TEMPERATURE AND NUMBER DENSITY PROFILES OF A GAS-FLOW FIELD SO APPLIED OPTICS LA English DT Article ID SPECTRAL-RESOLUTION LIDAR; ATMOSPHERIC-TEMPERATURE; SYSTEM AB Rayleigh-Brillouin spectra for heated nitrogen gas were measured by imaging the output of a Fabry-Perot interferometer onto a CCD array The spectra were compared with the theoretical 6-moment model of Rayleigh-Brillouin scattering convolved with the Fabry-Perot instrument function. Estimates of the temperature and a dimensionless parameter proportional to the number density of the gas as functions of position in the laser beam were calculated by least-squares deviation fits between theory and experiment. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. CALSPAN CORP, NASA LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP CLEVELAND STATE UNIV, DEPT PHYS, CLEVELAND, OH 44115 USA. NR 36 TC 18 Z9 19 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 MAY 20 PY 1992 VL 31 IS 15 BP 2839 EP 2848 PG 10 WC Optics SC Optics GA HU712 UT WOS:A1992HU71200029 PM 20725219 ER PT J AU TURNER, TJ DONE, C MUSHOTZKY, R MADEJSKI, G KUNIEDA, H AF TURNER, TJ DONE, C MUSHOTZKY, R MADEJSKI, G KUNIEDA, H TI EVIDENCE FOR AN IONIZED REPROCESSOR IN NGC-6814 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; GALAXIES, INDIVIDUAL (NGC-6814); GALAXIES, SEYFERT; X-RAYS, GALAXIES ID X-RAY-FLUORESCENCE; SEYFERT-GALAXIES; COLD MATTER; IRON; VARIABILITY; ABSORPTION; REFLECTION; SPECTRA; NUCLEI; EXOSAT AB We report a detailed spectroscopic analysis of a Ginga observation of the Seyfert galaxy NGC 6814. We show that the X-ray data are consistent with a scenario in which the continuum radiation is reprocessed in a highly ionized medium, which can either be an accretion disk or a shell of absorbing material. Both of these can produce the strong observed iron K-alpha line, which must originate within 200 lt-sec of the continuum source. Significant iron K-beta and nickel K-alpha are predicted, based on the iron K-alpha line strength, and these lines partially conceal the iron edge in this source. The spectral variability below approximately 4 keV, where the apparent absorption increases as the continuum flux decreases, is probably caused by a warm absorber covering the reprocessing system. C1 NAGOYA UNIV,DEPT ASTROPHYS,NAGOYA,AICHI 464,JAPAN. RP TURNER, TJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 44 TC 33 Z9 33 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1992 VL 391 IS 1 BP 102 EP 110 DI 10.1086/171327 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HT591 UT WOS:A1992HT59100007 ER PT J AU PETUCHOWSKI, SJ BENNETT, CL AF PETUCHOWSKI, SJ BENNETT, CL TI SO IN STARBURST GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-253, M82); GALAXIES, ISM; ISM, ABUNDANCES; ISM, MOLECULES ID MOLECULAR GAS; CLOUDS; FORMALDEHYDE; CHEMISTRY AB We describe the use of SO and SO2 as probes of the dense interstellar medium in the nearby starburst galaxies NGC 253 and M82. Emission in the 99.3 GHz 3(2) --> 2(1) rotational transition of SO was detected in NGC 253 and possibly in M82, and upper limits are reported for emission in the 219.9 GHz 6(5) --> 5(4) transition of SO and two lines of SO2. The column density of SO relative to carbon sulfide, CS, is [N(SO)/N(CS)] > 8 x 10(-2) in NGC 253. a value not much lower than Galactic ratios and consistent with models of dense interstellar clouds (Prasad & Huntress) with a fractional abundance of atomic oxygen greater than or similar to 10(-7). The 218.8 GHz 3(21) --> 2(20) transition of para-formaldehyde, with an excitation temperature of 68 K, was also detected in NGC 253. RP PETUCHOWSKI, SJ (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, MC 685, GREENBELT, MD 20771 USA. NR 25 TC 13 Z9 13 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1992 VL 391 IS 1 BP 137 EP 140 DI 10.1086/171330 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HT591 UT WOS:A1992HT59100010 ER PT J AU SEN, AD ANICICH, VG FEDERMAN, SR AF SEN, AD ANICICH, VG FEDERMAN, SR TI FORMALDEHYDE REACTIONS IN DARK CLOUDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, MOLECULES; MOLECULAR PROCESSES ID INTER-STELLAR CLOUDS; GAS-PHASE CHEMISTRY; DISSOCIATIVE RECOMBINATION; ASSOCIATION REACTIONS; INTERSTELLAR CLOUDS; LOW-PRESSURE; HCO+; IONS; COEFFICIENTS; TEMPERATURE AB The low-pressure reactions of formaldehyde (H2CO) with D+, D2+, D3+, and He+ have been studied by the ion cyclotron resonance technique. These reactions are potential loss processes for formaldehyde in cores of dark interstellar clouds. The deuterated reactants, which are easier to study experimentally, represent direct analogs for protons. Rate coefficients and branching ratios of product channels have been measured. Charge transfer is observed to be the dominant reaction of H2CO with D+, D2+ and He+ ions. Only the D3+ reaction exhibits a proton transfer channel. All reactions proceed at rate coefficients near the collision limit. Proton-deuteron exchange reactions were found to be inefficient processes in the formaldehyde system. C1 UNIV TOLEDO,DEPT PHYS & ASTRON,TOLEDO,OH 43606. RP SEN, AD (reprint author), CALTECH,JET PROP LAB,MS 183-601,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 26 TC 5 Z9 5 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1992 VL 391 IS 1 BP 141 EP 143 DI 10.1086/171331 PN 1 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HT591 UT WOS:A1992HT59100011 ER PT J AU ASCHWANDEN, MJ BASTIAN, TS BENZ, AO BROSIUS, JW AF ASCHWANDEN, MJ BASTIAN, TS BENZ, AO BROSIUS, JW TI DECIMETRIC SOLAR TYPE-U BURSTS - VLA AND PHOENIX OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, CORONA; SUN, MAGNETIC FIELDS; SUN, RADIO RADIATION ID FLARING ARCHES; RADIO-BURSTS; FLARES; EMISSION; NOVEMBER; EVENTS AB We report on observations of type U bursts, simultaneously detected by the Very Large Array at 1.446 GHz and by the broad-band spectrometer PHOENIX (ETH Zurich) in the 1.1-1.7 GHz frequency band. The VLA was operated with a time resolution of 1.66 s, while PHOENIX used a time resolution of 40 ms. A sequence of approximately 6 inverted-U bursts with similar morphology occurred between 1355-1359 UT, on 1989 August 13, accompanied by a soft X-ray flare of GOES class C6.6. The peak flux was 7 SFU above background. The narrow bandwidth of almost-equal-to 10% and the weak polarization in the sense of the ordinary mode is consistent with harmonic plasma emission. The turnover frequency of 1.4 GHz at the top of the U bursts then corresponds to a plasma density of 6 x 10(9) cm-3, while the footpoints at more than 1.7 GHz are rooted in densities greater than approximately 10(10) cm-3. Extrapolations of the coronal magnetic field, assuming a potential configuration, indicate that the VLA 20 cm source demarcates an isodensity level. The source covers a wide angle of diverging magnetic field lines whose footpoints originate close to a magnetic intrusion of negative polarity into the main sunspot group of the active region (NOAA/USAF 5629) with dominant positive polarity. The centroid of the 20 cm U-burst emission, which corresponds to the turnover frequency of the type U bursts and remains stationary during all U bursts, coincides with the apex of extrapolated potential field lines at a height of almost-equal-to 130,000 km. We interpret the U bursts in terms of electron beams propagating in closed coronal loops. However, the viability of the electron beam model requires: (1) a high ambient temperature in the relevant coronal loops (T greater than or similar to 7 x 10(6) K); (2) magnetic field strengths higher than those implied by potential field extrapolations; i.e., the existence of nonpotential fields. The exciter speed of three type U bursts is estimated to be v = 42,000-64,000 km s-1. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. NATL RADIO ASTRON OBSERV, SOCORRO, NM 87801 USA. ETH ZURICH, INST ASTRON, CH-8029 ZURICH, SWITZERLAND. NR 38 TC 44 Z9 45 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1992 VL 391 IS 1 BP 380 EP 392 DI 10.1086/171353 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HT591 UT WOS:A1992HT59100033 ER PT J AU JUNG, YD GOULD, RJ AF JUNG, YD GOULD, RJ TI L-SHELL X-RAY OPACITY OF MANY-ELECTRON ATOMS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC DATA; X-RAYS, GENERAL AB A formulation is developed for obtaining the L-shell photoelectric cross section (sigma(L)) for many-electron atomic systems. A scaling law is suggested for the evaluation of the contribution to sigma(L) from 2s and 2p ejection from a general system in any ionization state. The formula is expressed in terms of the effective nuclear charge (Z2s and Z2p) seen by the corresponding bound electrons. with Z2s and Z2p obtained from improved screening constants derived in a recent investigation. A comparison is made of Hartree-Fock and hydrogenic expressions for sigma(L) with experimental results for atomic neon at X-ray photon energies, providing the basis for the scaling law and an approximate energy dependence for the cross sections. The special case of sigma(L) for atomic Fe is considered in more detail, since the L threshold is at soft X-ray energies around 0.8 keV. This L edge has structure because of the different thresholds for 2s and 2p photoejection; the latter has fine structure. For neutral Fe. accurate Hartree-Fock calculations are taken for the threshold energies; these should be more accurate than values currently being employed, which are experimental quantities for solid Fe. The corresponding threshold structure for atomic Fe+ is also evaluated in an approximate way. From the results in this work the X-ray opacity contribution from L-shell photoejection can be evaluated easily for any condition in the interstellar gas or in discrete X-ray sources. The work then compliments that performed for the K-shell contribution in a recent paper by the authors. C1 UNIV CALIF SAN DIEGO,DEPT PHYS,LA JOLLA,CA 92093. RP JUNG, YD (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 9 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 20 PY 1992 VL 391 IS 1 BP 403 EP 408 DI 10.1086/171355 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HT591 UT WOS:A1992HT59100035 ER PT J AU PALUCH, IR LENSCHOW, DH HUDSON, JG PEARSON, R AF PALUCH, IR LENSCHOW, DH HUDSON, JG PEARSON, R TI TRANSPORT AND MIXING PROCESSES IN THE LOWER TROPOSPHERE OVER THE OCEAN SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CARBON-MONOXIDE; OZONE; CHEMISTRY; DYNAMICS; TROPICS; CLOUDS AB Aircraft observations during the summer over the eastern Pacific Ocean, greater-than-or-equal-to 400 km offshore, show that the free troposphere has a distinctly nonuniform, layered structure. Analysis of plots of ozone versus total water mixing ratio indicates that the layers typically consist of a mixture of air from several sources: (1) moist, ozone-depleted boundary layer air, (2) very dry air with high ozone content, which probably originated in the middle or upper troposphere, and (3) air with relatively low ozone and moderate, varying moisture contents, which may represent residues of convective clouds that had formed over the ocean upstream of the research area. On two research days we also observed what we infer to be continental air. On one day in the usual research area we encountered air with elevated concentrations of aerosols whose trajectories, traced backward in time, indicated that it had passed over the Alaskan continent. On another day, when soundings were made about 100 km off the California coast, we observed a layer just above the marine inversion containing unusually high amounts of ozone, aerosols, and moisture. This layer probably represents a direct intrusion of polluted air from the coast, which could have been the result of baroclinic flow associated with boundary layer warming over land. Over the eastern Pacific Ocean in summer the subtropical high results in stably stratified, subsiding air, where discrete horizontal layers with differing flow velocities transport air over long distances with little vertical mixing. Here, localized large-scale flows (such as tropospheric folding, deep convection, or baroclinic flow from coastal areas) "inject" air of different properties at various levels in the lower troposphere. This air is then subject to buoyancy sorting and differential advection. Because the lower troposphere is very stably stratified, the mixing eddies are small compared to the air mass size, and small-scale turbulent diffusion is slow. Here, wind shear plays an important role through stretching and thinning the different air masses until small-scale diffusion completes the mixing process. C1 DESERT RES INST, RENO, NV 89506 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP NATL CTR ATMOSPHER RES, POB 3000, BOULDER, CO 80307 USA. OI LENSCHOW, DONALD/0000-0003-4353-0098 NR 28 TC 34 Z9 34 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 20 PY 1992 VL 97 IS D7 BP 7527 EP 7541 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HV487 UT WOS:A1992HV48700004 ER PT J AU CESS, RD HARRISON, EF MINNIS, P BARKSTROM, BR RAMANATHAN, V KWON, TY AF CESS, RD HARRISON, EF MINNIS, P BARKSTROM, BR RAMANATHAN, V KWON, TY TI INTERPRETATION OF SEASONAL CLOUD-CLIMATE INTERACTIONS USING EARTH RADIATION BUDGET EXPERIMENT DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODELS; FEEDBACK AB This investigation proposes an approach for using satellite radiation budget data to interpret and understand seasonal cloud-climate interactions in a manner that can serve as one means of testing and improving numerical climate models. By employing Earth Radiation Budget Experiment data it is demonstrated that, relative to the annual-mean climate, seasonal cloud variations produce radiative heating of the surface-atmosphere system in the summer hemisphere, together with cooling in the winter hemisphere. It is further illustrated that this is an integrated effect resulting from the combination of seasonal variations in cloud amount, cloud vertical distribution, and cloud optical depth. C1 NASA, LANGLEY RES CTR, ATMOSPHER SCI RES CTR, HAMPTON, VA 23665 USA. UNIV CALIF SAN DIEGO, SCRIPPS INST OCEANOG, LA JOLLA, CA 92093 USA. UNIV CALIF SAN DIEGO, CALIF SPACE INST, LA JOLLA, CA 92093 USA. RP CESS, RD (reprint author), SUNY STONY BROOK, INST TERR & PLANETARY ATMOSPHERES, STONY BROOK, NY 11794 USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 6 TC 26 Z9 26 U1 0 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAY 20 PY 1992 VL 97 IS D7 BP 7613 EP 7617 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HV487 UT WOS:A1992HV48700011 ER PT J AU SCHAEFER, WP SPOTTS, JM MARDER, SR AF SCHAEFER, WP SPOTTS, JM MARDER, SR TI AN ORGANOMETALLIC CYANINE - MU-1,3,5-HEPTATRIENE-1,7-DIYLIDENE-BIS[MU-2-CARBONYL-DICARBONYLBIS(ETA-5 -CYCLOPENTADIENYL)DIIRON] TETRAFLUOROBORATE SO ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS LA English DT Article ID X-RAY STRUCTURE; COMPLEXES; BINUCLEAR; CRYSTAL AB C33H25Fe4O6+.BF4-, M(r) = 827.75, monoclinic, C2/c, a = 32.289 (10), b = 8.984 (3), c = 28.024 (10) angstrom, beta = 126.84 (2)-degrees, V = 6506 (4) angstrom3, Z = 8, D(x) = 1.69 g cm-3, Mo K-alpha, lambda = 0.71073 angstrom, mu = 18.2 cm-1, F(000) = 3328, T = 297 K, R = 0.047 for 2619 reflections with F(o)2> 0. This compound has an intense low-energy visible absorption band (epsilon = 165 500 at 630 nm); the material is likely to be useful in non-linear optical devices. The Fe2-C7-Fe2 group is planar within +/- 0.14 angstrom and all the C-C bonds in the bridge are essentially the same length, 1.379 (11) angstrom. C1 CALTECH,CTR MOLEC MAT RESOURCE,BECKMAN INST,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91125. RP SCHAEFER, WP (reprint author), CALTECH,DIV CHEM & CHEM ENGN,PASADENA,CA 91125, USA. NR 15 TC 7 Z9 7 U1 0 U2 0 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0108-2701 J9 ACTA CRYSTALLOGR C JI Acta Crystallogr. Sect. C-Cryst. Struct. Commun. PD MAY 15 PY 1992 VL 48 BP 811 EP 814 DI 10.1107/S010827019101199X PN 5 PG 4 WC Chemistry, Multidisciplinary; Crystallography SC Chemistry; Crystallography GA HX601 UT WOS:A1992HX60100014 ER PT J AU HOCHSTEIN, LI STANLOTTER, H AF HOCHSTEIN, LI STANLOTTER, H TI PURIFICATION AND PROPERTIES OF AN ATPASE FROM SULFOLOBUS-SOLFATARICUS SO ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS LA English DT Article ID MEMBRANE-BOUND ATPASE; ARCHAEBACTERIUM HALOBACTERIUM-SACCHAROVORUM; CHEMIOSMOTIC ENERGY-CONVERSION; ACIDOTHERMOPHILIC ARCHAEBACTERIUM; ADENOSINE-TRIPHOSPHATASE; METHANOSARCINA-BARKERI; BETA-SUBUNIT; ACIDOCALDARIUS; VACUOLAR; PHOSPHATE C1 SETI INST,MT VIEW,CA 94043. RP HOCHSTEIN, LI (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 32 TC 23 Z9 23 U1 2 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0003-9861 J9 ARCH BIOCHEM BIOPHYS JI Arch. Biochem. Biophys. PD MAY 15 PY 1992 VL 295 IS 1 BP 153 EP 160 DI 10.1016/0003-9861(92)90501-M PG 8 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA HQ209 UT WOS:A1992HQ20900023 PM 1533499 ER PT J AU PARTRIDGE, H BAUSCHLICHER, CW SODUPE, M LANGHOFF, SR AF PARTRIDGE, H BAUSCHLICHER, CW SODUPE, M LANGHOFF, SR TI AN ABINITIO STUDY OF THE IONIZATION OF SODIUM SUPEROXIDE - COMMENT SO JOURNAL OF CHEMICAL PHYSICS LA English DT Letter ID 2ND-ROW ATOMS; BASIS-SETS RP PARTRIDGE, H (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Sodupe, Mariona/E-9352-2013 OI Sodupe, Mariona/0000-0003-0276-0524 NR 10 TC 9 Z9 9 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD MAY 15 PY 1992 VL 96 IS 10 BP 7871 EP 7871 DI 10.1063/1.462389 PG 1 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA HU557 UT WOS:A1992HU55700073 ER PT J AU BARNETT, TP DELGENIO, AD RUEDY, RA AF BARNETT, TP DELGENIO, AD RUEDY, RA TI UNFORCED DECADAL FLUCTUATIONS IN A COUPLED MODEL OF THE ATMOSPHERE AND OCEAN MIXED LAYER SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SEA-SURFACE TEMPERATURE; STOCHASTIC CLIMATE MODELS; AIR TEMPERATURES; VARIABILITY; CIRCULATION; FORECAST AB Global average temperature in a 100-year control run of a model used for greenhouse gas response simulations showed low-frequency natural variability comparable in magnitude to that observed over the last 100 years. The model variability was found to be barotropic in the atmosphere, and located in the tropical strip with largest values near the equator in the Pacific. The model variations were traced to complex, low-frequency interactions between the meridional sea surface temperature gradients in the eastern equatorial Pacific, clouds at both high and low levels, and features of the tropical atmospheric circulation. The variations in these and other model parameters appear to oscillate between two limiting climate states. The physical scenario accounting for the oscillations on decadal time scales is almost certainly not found in the real world on shorter time scales due to limited resolution and the omission of key physics (e.g., equatorial ocean dynamics) in the model. The real message is that models with dynamical limitations can still produce significant long-term variability. Only a thorough physical diagnosis of such simulations and comparisons with decadal-length data sets will allow one to decide if faith in the model results is, or is not, warranted. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP BARNETT, TP (reprint author), UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,DIV CLIMATE RES,LA JOLLA,CA 92093, USA. RI Del Genio, Anthony/D-4663-2012 OI Del Genio, Anthony/0000-0001-7450-1359 NR 26 TC 21 Z9 21 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD MAY 15 PY 1992 VL 97 IS C5 BP 7341 EP 7354 DI 10.1029/92JC00501 PG 14 WC Oceanography SC Oceanography GA HU911 UT WOS:A1992HU91100010 ER PT J AU BARNES, JR YOUNG, RE AF BARNES, JR YOUNG, RE TI NONLINEAR BAROCLINIC INSTABILITY ON THE SPHERE - MULTIPLE LIFE-CYCLES WITH SURFACE DRAG AND THERMAL DAMPING SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID SOUTHERN-HEMISPHERE SUMMER; SCALE WAVE DYNAMICS; SPECTRAL MODEL; TROPOSPHERE; FLOW; CIRCULATION; ENERGETICS; EVOLUTION; GROWTH; EDDIES AB A multilevel, global, primitive equation model is used to examine the nonlinear development of baroclinic waves (confined initially to a single zonal wavenumber) on a symmetric zonal flow. The focus is on the influence of highly simplified surface drag and thermal damping on the evolution of the flow beyond an initial eddy life cycle. Without surface drag and thermal damping and with relatively weak internal diffusion, it is found that multiple life cycles occur in the evolution to an essentially wave-free state. With stronger diffusion, only a single life cycle characterized by baroclinic growth and barotropic decay is obtained. The life cycles that follow the initial cycle with weak diffusion are strongly barotropic, entailing barotropic growth and decay. The episodes of barotropic growth are associated with wave radiation, wave breaking, and overreflection on the equatorward flanks of the jet near a critical surface. With strong diffusion, the potential vorticity mixing associated with the breaking is reduced considerably, and significant barotropic growth (and overreflection) does not occur. In all the simulations without drag and damping, the "barotropic governor" identified by James and Gray is primarily responsible for the stabilization of the mean flow in the final wave-free state. Repeated life cycles characterized largely by baroclinic growth and barotropic decay are obtained with the simplified surface drag and thermal damping. Significant barotropic growth occurs in the early stages of most of the life cycles, associated with wave breaking and overreflection on the equatorward side of the jet. Multiple life cycles of baroclinic growth and barotropic decay occur in the complete absence of thermal damping (though damping is certainly necessary for sustained life cycles), demonstrating the crucial role of surface drag in suppressing the barotropic governor. With thermal damping but without surface drag, the evolution is similar to that without both drag and damping in being highly barotropic. The simulations with surface drag and thermal damping are compared with observations of medium-scale baroclinic waves in Southern Hemisphere summer and are found to be very similar. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP BARNES, JR (reprint author), OREGON STATE UNIV,DEPT ATMOSPHER SCI,STRAND AGR HALL 326,CORVALLIS,OR 97331, USA. NR 38 TC 22 Z9 22 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD MAY 15 PY 1992 VL 49 IS 10 BP 861 EP 878 DI 10.1175/1520-0469(1992)049<0861:NBIOTS>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HU245 UT WOS:A1992HU24500004 ER PT J AU WU, KW WICKRAMASINGHE, DT AF WU, KW WICKRAMASINGHE, DT TI 3-DIMENSIONAL STRUCTURED SHOCKS IN AM HERCULIS-TYPE SYSTEMS .2. CYCLOTRON EMISSION FROM RIDGE-SHAPED EMISSION REGIONS SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE ACCRETION, ACCRETION DISKS; RADIATION MECHANISMS, CYCLOTRON AND SYNCHROTRON; STARS, MAGNETIC FIELDS; NOVAE, CATACLYSMIC VARIABLES ID INHOMOGENEOUS ACCRETION COLUMNS; POLARIZATION PROPERTIES; TEMPERATURE; ABSORPTION; E1405-451; RADIATION; BINARIES; FEATURES; SPECTRA; FIELD AB We study the properties of cyclotron emission from accretion shocks in AM Herculis binaries which result from non-uniform accretion on to linearly extended regions on the surface of the magnetic white dwarf. We show that the resulting ridge-shaped post-shock structures yield cyclotron spectra with prominent harmonic features over a wide range of viewing aspects, even for high total accretion rates, in contrast to what has been found previously for axisymmetric accretion shocks. C1 AUSTRALIAN NATL UNIV,DEPT MATH,CANBERRA,ACT 2601,AUSTRALIA. RP WU, KW (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES-65,HUNTSVILLE,AL 35812, USA. NR 41 TC 5 Z9 5 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD MAY 15 PY 1992 VL 256 IS 2 BP 329 EP 338 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HU177 UT WOS:A1992HU17700017 ER PT J AU NOEVER, DA AF NOEVER, DA TI OLIGOMERIC BAROEFFECT AND GAS AGGREGATION STATES SO PHYSICAL REVIEW A LA English DT Article ID VAPOR TRANSPORT AB The baroeffect is analyzed to include a gas that aggregates into higher-order polymers or oligomers. The resulting pressure change is found to vary independently of the molecular weight of the gas components and to depend only on the aggregation or oligomeric order of the gas. With increasing aggregation, diffusive slip velocities are found to increase. The calculations are extended to include general counterdiffusion of two distinct aggregation states (k-, j-mer) for the gas, and the pressure change is derived as a function that is independent of both molecular weight and the absolute aggregation. The only parameter that determines the baroeffect is the ratio of aggregated states, beta = k/j. For gases that reversibly aggregate, possible oscillatory behavior and complex dynamics for pressure are discussed. Gas aggregation may play a role for low-temperature crystal-growth conditions in which vapor concentrations of one (or more) species are high. RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES-76,HUNTSVILLE,AL 35812, USA. NR 34 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 MAY 15 PY 1992 VL 45 IS 10 BP 7302 EP 7308 DI 10.1103/PhysRevA.45.7302 PG 7 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA HV267 UT WOS:A1992HV26700047 ER PT J AU HAHNE, GE AF HAHNE, GE TI TRANSITION OPERATORS IN ELECTROMAGNETIC-WAVE DIFFRACTION THEORY - GENERAL-THEORY SO PHYSICAL REVIEW A LA English DT Article ID INVERSE AB The objective of this paper is the establishment of a formal theory of the scattering of time-harmonic electromagnetic waves from impenetrable, immobile obstacles, with given linear, homogeneous, and generally nonlocal, boundary conditions of Leontovich (i.e., impedance) type for the wave on the obstacle's surface partial derivative-OMEGA. As in an analogous treatment of acoustic-wave diffraction by the author [G.E. Hahne, Phys. Rev. A 43, 976 (1991); 43, 990 (1991)], the theory is modeled on the theory of the complete Green's function and the transition (T) operator in time-independent formal scattering theory of nonrelativistic quantum mechanics. For each nonzero free-space wave number k0, the electromagnetic field is described kinematically in terms of a six-component entity comprising the direct sum of the electric and the magnetic three-vector field at each point of position space; an electromagnetic source is described correspondingly as a six-component entity comprising the direct sum of the time-harmonic electric and magnetic current distributions. Accordingly, the Green's function and the T operator are 6 x 6 matrices of two-point, complex-valued, k0-dependent functions. A simplified expression is obtained for the T operator for a general case of nonlocal, homogeneous Leontovich boundary conditions for the electromagnetic wave on partial derivative-OMEGA. Analogous to the acoustic case, all the nonelementary operators that enter the expression for the T operator are formally simple, rational algebraic functions of a certain invertible, linear, k0-dependent operator Z(k)0+ which is called the radiation impedance operator; Z(k)0+ is an operator of the class that maps the linear space of complex tangent-vector fields on partial derivative-OMEGA onto itself. The nonlocal operator Z(k)0+ is defined only implicitly, in that, apart from a simple transformation made for technical reasons, it is the operator that maps the tangential magnetic field on partial derivative-OMEGA of an outgoing-wave solution to the source-free Maxwell equations into the uniquely corresponding tangential electric field. The paper concludes with a derivation of an expression for the differential scattering cross section for plane electromagnetic waves in terms of certain matrix elements of the T operator for the obstacle, and a proposal for a class of Leontovich boundary conditions that, if realized, would yield exactly zero scattering amplitude at a given k0. There are four appendixes: The first appendix recapitulates the theory of the free-space Green's function for the time-harmonic Maxwell field and the relationship of this Green's function to certain linear functional operators defined on the space of tangent-vector fields on the obstacle's boundary. The second appendix establishes mathematical conditions on the defining operators for the Leontovich boundary conditions, which conditions are sufficient to guarantee the uniqueness and existence of the complete Green's function, and reciprocity for the Green's functions of purely outgoing-wave type. The third appendix argues that any of a certain class of time-harmonic, linear electromagnetic scattering problems admits to a partial decoupling into a separate problem for the region interior and the region exterior to a dividing surface; a complete set of interior solutions determines exactly one equivalence class of Leontovich boundary conditions for the exterior electromagnetic field, so that the solution of a scattering problem then reduces to a problem in functional analysis in the space of tangent-vector fields on the dividing surface, as described in the main part of the paper. The fourth appendix describes a linear network analog to the formal scattering theory established herein. RP HAHNE, GE (reprint author), NASA,AMES RES CTR,COMPUTAT CHEM BRANCH,MOFFETT FIELD,CA 94035, USA. NR 57 TC 3 Z9 3 U1 1 U2 1 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 MAY 15 PY 1992 VL 45 IS 10 BP 7526 EP 7548 DI 10.1103/PhysRevA.45.7526 PG 23 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA HV267 UT WOS:A1992HV26700070 ER PT J AU SHING, YH POOL, FS RICH, DH AF SHING, YH POOL, FS RICH, DH TI LOW-PRESSURE MICROWAVE PLASMA NUCLEATION AND DEPOSITION OF DIAMOND FILMS SO THIN SOLID FILMS LA English DT Article; Proceedings Paper CT CONF ON APPLIED DIAMOND CY AUG 17-22, 1991 CL AUBURN UNIV, AUBURN, AL HO AUBURN UNIV ID CHEMICAL-VAPOR-DEPOSITION; RESONANT RAMAN-SCATTERING; AMORPHOUS-CARBON; GAS-PHASE; CATHODOLUMINESCENCE AB Low-pressure microwave plasma nucleation and deposition of diamond films were investigated in the pressure range 10 mTorr to 10 Torr, at low substrate temperatures of 400-750-degrees-C, using high methane concentration of 2%-15% and oxygen concentrations of 2%-10% in hydrogen plasmas. Diamond film deposition was performed in a microwave plasma system consisting of a microwave plasma chamber, a downstream deposition chamber and an r.f. induction heated sample stage. The deposition system can be operated in either localized microwave plasmas or extended electron cyclotron resonance (ECR) plasmas by varying the sample stage position. Initial nucleation for diamond growth was achieved by ECR plasmas under a low pressure of 13 mTorr and at 600-degrees-C. Diamond nucleation on BN and SiC interlayer materials was demonstrated by depositing well faceted diamond crystallites onto amorphous BN and cubic SiC coated silicon substrates. Low-pressure ECR microwave plasma deposition and the use of BN and SiC as interlayer materials for coating substrates are new practical methods for generating diamond nuclei to promote diamond film growth on non-diamond surfaces. Cathodoluminescence (CL) studies on diamond films deposited at 10 Torr pressure show that CL emissions at 430, 530, 560 and 740 nm can be employed to characterize the quality of diamond films. Scanning electron microscopy (SEM) of diamond films deposited at 600-degrees-C with 5% CH4 and 5% O2 in H2 plasmas has shown high-quality well faceted crystallites of 1/2-mu-m sizes. CL measurements on these diamond films show very few nitrogen impurities and no detectable silicon impurities. RP SHING, YH (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 10 Z9 10 U1 0 U2 1 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0040-6090 J9 THIN SOLID FILMS JI Thin Solid Films PD MAY 15 PY 1992 VL 212 IS 1-2 BP 150 EP 155 DI 10.1016/0040-6090(92)90513-B PG 6 WC Materials Science, Multidisciplinary; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA HW794 UT WOS:A1992HW79400023 ER PT J AU RAO, MVVS SRIVASTAVA, SK AF RAO, MVVS SRIVASTAVA, SK TI TOTAL AND PARTIAL IONIZATION CROSS-SECTIONS OF NH3 BY ELECTRON-IMPACT SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID DISSOCIATIVE IONIZATION; AMMONIA; GAS; THRESHOLD; H2O AB Values of cross sections for the production of positive ions resulting from electron collisions with NH3 at impact energies ranging from threshold to 1 keV have been measured using a crossed-beams apparatus. These cross sections have been normalized by using the relative flow technique and the previously determined cross sections of He and Ne. The measured values are compared with previous data available in the literature. The threshold energy for the production of each ion has been measured. Total ionization cross sections as a function of electron impact energies have been deduced from the measured partial ionization cross sections. RP RAO, MVVS (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 29 TC 28 Z9 28 U1 1 U2 7 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD MAY 14 PY 1992 VL 25 IS 9 BP 2175 EP 2187 DI 10.1088/0953-4075/25/9/021 PG 13 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA HV657 UT WOS:A1992HV65700021 ER PT J AU KANIK, I NICKEL, JC TRAJMAR, S AF KANIK, I NICKEL, JC TRAJMAR, S TI TOTAL ELECTRON-SCATTERING CROSS-SECTION MEASUREMENTS FOR KR, O-2 AND CO SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID ENERGY POSITRONS; XE; AR AB Total cross sections have been measured for electron scattering on Kr, O2 and CO in the 5-300 eV energy range utilizing a linear attenuation technique. The present results are found to be in good agreement with other experimental data for Kr and CO but deviate significantly from some of the previous measurements in the case of O2. C1 UNIV CALIF RIVERSIDE, DEPT PHYS, RIVERSIDE, CA 92521 USA. RP JET PROP LAB, PASADENA, CA 91109 USA. NR 27 TC 27 Z9 27 U1 0 U2 5 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0953-4075 EI 1361-6455 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD MAY 14 PY 1992 VL 25 IS 9 BP 2189 EP 2196 DI 10.1088/0953-4075/25/9/022 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA HV657 UT WOS:A1992HV65700022 ER PT J AU MCCONKEY, JW TRAJMAR, S MAN, KF RATLIFF, JM AF MCCONKEY, JW TRAJMAR, S MAN, KF RATLIFF, JM TI EXCITATION OF NAPHTHALENE BY ELECTRON-IMPACT SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID SINGLE VIBRONIC LEVELS; POLYCYCLIC AROMATIC-HYDROCARBONS; JET-COOLED NAPHTHALENE; VAPOR-PHASE; FLUORESCENCE-SPECTRA; EMISSION FEATURES; MOLECULES; STATES; SPECTROSCOPY; SCATTERING AB Absolute, apparent cross sections for 295-410 nm band emission from naphthalene have been measured over an electron-impact energy range from threshold to 300 eV. Numerous processes, including electron exchange, are observed to contribute to the excitation in the near threshold region. At higher energies direct excitation through optically allowed channels is preferred. The electron-impact-induced fluorescence was found to be. unpolarized (< 0.5%) in the near-threshold region but showed small negative polarizations of a few per cent at impact energies greater than 25 eV. The radiation decay occurs to excited vibrational levels of the ground electronic state which is expected to lead to strong IR emission. C1 UNIV WINDSOR,DEPT PHYS,WINDSOR N9B 3P4,ONTARIO,CANADA. RP MCCONKEY, JW (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 40 TC 10 Z9 10 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD MAY 14 PY 1992 VL 25 IS 9 BP 2197 EP 2204 DI 10.1088/0953-4075/25/9/023 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA HV657 UT WOS:A1992HV65700023 ER PT J AU MOLLERACH, S ROULET, E AF MOLLERACH, S ROULET, E TI LOW-TEMPERATURE BARYOGENESIS AND THE AXION SUPERMULTIPLET SO PHYSICS LETTERS B LA English DT Article ID ELECTRIC-DIPOLE MOMENT; BARYON-NUMBER; NEUTRINO MASSES; CP VIOLATION; UNIVERSE; SUPERGRAVITY; SEARCH; SCALE AB We consider the possibility that the baryon asymmetry is generated at low temperatures as a consequence of the decay of one of the supermultiplet axion companions: the axino or the saxino. We analyse models in which these particles are heavy and decay producing gluinos at temperatures T is similar-to 1 GeV. If CP and B violating couplings for the quark superfields are included, the subsequent decay of these out of equilibrium gluinos can act as seeds for baryogenesis. The most attractive features of this scenario are that the required amount of CP violation is small, well consistent with the bounds on the electric dipole moment of the neutron. and the mechanism works even for low reheating temperatures after inflation (T(RH) greater than of similar to 10(4) GeV). RP MOLLERACH, S (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,POB 500,BATAVIA,IL 60510, USA. NR 31 TC 22 Z9 22 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-2693 J9 PHYS LETT B JI Phys. Lett. B PD MAY 14 PY 1992 VL 281 IS 3-4 BP 303 EP 308 DI 10.1016/0370-2693(92)91145-Y PG 6 WC Astronomy & Astrophysics; Physics, Nuclear; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA JA781 UT WOS:A1992JA78100022 ER PT J AU MASIERO, A PAKVASA, S ROULET, E TATA, X AF MASIERO, A PAKVASA, S ROULET, E TATA, X TI AN UNMIXED 17-KEV NEUTRINO SO PHYSICS LETTERS B LA English DT Article ID LEFT-RIGHT-SYMMETRY; HEAVY-NEUTRINO; BETA-DECAY; SEARCH; SUPERNOVA; EMISSION; SN1987A; S-35 AB We argue that the observation of the kink in the electron energy spectrum in beta-decay does not necessarily imply mixing amongst the neutrinos. We have constructed a model in which the kink occurs because the neutron can also beta-decay into an isosinglet neutrino (with a Dirac mass of 17 keV) via a new interaction mediated by spin zero, Q = -1/3 leptoquarks with a mass of 100-1000 1000 GeV. Our model can be tested by modest improvements in the measurement of the longitudinal polarisation of electrons in beta-decay and in the branching fraction of the pion decay to electron. Astrophysical and cosmological implications of this new interaction of neutrinos are also discussed. C1 UNIV HAWAII,DEPT PHYS & ASTRON,HONOLULU,HI 96822. NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. RP MASIERO, A (reprint author), IST NAZL FIS NUCL,I-35131 PADUA,ITALY. NR 53 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0370-2693 J9 PHYS LETT B JI Phys. Lett. B PD MAY 14 PY 1992 VL 281 IS 3-4 BP 351 EP 356 DI 10.1016/0370-2693(92)91154-2 PG 6 WC Astronomy & Astrophysics; Physics, Nuclear; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA JA781 UT WOS:A1992JA78100031 ER PT J AU DEISSLER, RJ ORON, A AF DEISSLER, RJ ORON, A TI STABLE LOCALIZED PATTERNS IN THIN LIQUID-FILMS SO PHYSICAL REVIEW LETTERS LA English DT Article ID CONFINED STATES; PHASE DYNAMICS AB We study a two-dimensional nonlinear evolution equation which describes the three-dimensional spatiotemporal behavior of the air-liquid interface of a thin liquid film lying on the underside of a cooled horizontal plate. We show that the equation has a Liapunov functional and exploit this fact to demonstrate that the Marangoni effect can stabilize the destabilizing effect of gravity (the Rayleigh-Taylor instability) allowing for the existence of stable localized axisymmetric solutions for a wide range of parameter values. Various properties of these structures are discussed. C1 TECHNION ISRAEL INST TECHNOL,DEPT MECH ENGN,IL-32000 HAIFA,ISRAEL. RP DEISSLER, RJ (reprint author), NASA,LEWIS RES CTR,INST COMPUTAT MECH PROPULS,CLEVELAND,OH 44135, USA. NR 15 TC 40 Z9 40 U1 1 U2 7 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 MAY 11 PY 1992 VL 68 IS 19 BP 2948 EP 2951 DI 10.1103/PhysRevLett.68.2948 PG 4 WC Physics, Multidisciplinary SC Physics GA HT648 UT WOS:A1992HT64800024 ER PT J AU LIU, HK AF LIU, HK TI SELF-AMPLIFIED OPTICAL PATTERN-RECOGNITION TECHNIQUE SO APPLIED OPTICS LA English DT Article DE SELF-AMPLIFICATION; PHOTOREFRACTIVE CRYSTAL; OPTICAL PATTERN RECOGNITION; VANDERLUGT MATCHED FILTER; 2-WAVE MIXING ID 2-WAVE MIXING EXPERIMENTS; HOLOGRAPHIC STORAGE; ENERGY-TRANSFER; ELECTROOPTIC CRYSTALS; BI12SIO20 CRYSTALS; AMPLIFICATION AB A self-amplified optical pattern-recognition technique that utilizes a photorefractive crystal as a real-time volume holographic filter with recording accomplished by means of laser beams of proper polarization and geometric configuration is described. After the holographic filter is recorded, it can be addressed with extremely weak object beams and an even weaker reference beam to obtain a pattern-recognition signal. Because of beam-coupling energy transfer from the input object beam to the diffracted beam, the recognition signal is greatly amplified. Experimental results of this technique using BaTiO3 crystal show that 5 orders of magnitude of amplification of a recognition signal can be obtained. RP CALTECH, JET PROP LAB, CTR MICROELECTR TECHNOL, PASADENA, CA 91109 USA. NR 25 TC 3 Z9 3 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD MAY 10 PY 1992 VL 31 IS 14 BP 2568 EP 2575 PG 8 WC Optics SC Optics GA HT103 UT WOS:A1992HT10300026 PM 20725184 ER PT J AU MEIXNER, M HAAS, MR TIELENS, AGGM ERICKSON, EF WERNER, M AF MEIXNER, M HAAS, MR TIELENS, AGGM ERICKSON, EF WERNER, M TI FAR-INFRARED OBSERVATIONS OF M17SW - THE CLUMPY STRUCTURE OF THE PHOTODISSOCIATION REGION SO ASTROPHYSICAL JOURNAL LA English DT Article DE H-II REGIONS; INFRARED-INTERSTELLAR-CONTINUUM; INFRARED-INTERSTELLAR-LINES; ISM-INDIVIDUAL (M17); ISM-MOLECULES; ISM-STRUCTURE ID NEUTRAL ATOMIC CARBON; H-II REGIONS; MOLECULAR CLOUD; LINE; EMISSION; MODEL; RESOLUTION; ABUNDANCE; COMPLEX; MICRON AB We have mapped [O I] 63-mu-m and [Si II] 35-mu-m fine-structure line emission in M17SW using the cooled grating spectrometer aboard NASA's Kuiper Airborne Observatory. In addition, we have measured the intensities of the [O I] 63 and 146-mu-m, [Si II] 35-mu-m, and [C ii] 158-mu-m at four positions. We have also made a strip scan of the [O I] 63-mu-m line intensity across the ionization front. Finally, we present new 50 and 100-mu-m continuum maps of the M17SW cloud at comparable resolution (30"-40") to the far-infrared line observations. The [O I] 63-mu-m and [Si-II] emission defines a thin (approximately 80", 0.85 pc) ridge which separates the ionized gas surrounding the luminous 0 stars in the northeast from the dense molecular core to the southwest. These observations demonstrate that the [Si II] arises from the photodissociation region (PDR) rather than the H II region. The [O I] map shows two distinct peaks along the ridge, which both border warm molecular clumps. The [Si II] map shows only one peak, which falls between the two [O I] peaks. The [Si II]/[O I] ratio varies somewhat over the mapped area, but is of order unity, considerably larger than predicted by the standard models. We have analyzed these new data together with earlier observations of molecular and ionized gas in this region. Assuming a homogeneous density distribution, numerical modeling yields densities and temperatures of approximately 3 x 1O(4) cm-3 and 300 K for the atomic zone. However, the homogeneous models cannot reproduce the observed spatial distributions, absolute intensities, and line ratios. Hence, we present a three-component model for the M17SW PDR consisting of clumps of density 5 x 10(5) cm-3 embedded in an interclump medium of density 3 x 10(3) cm-3. This clumpy core is surrounded by a halo with density 300 cm-3. This latter model agrees well with most of the observed spatial distributions and peak intensities of the far-infrared and submillimeter emission lines. In particular, the observed high [Si II]/[O I] 63-mu-m ratio is probably a result of the larger column density of clumps in an edge-on geometry in combination with self-absorption in the [O I] 63-mu-m by the interclump medium. We find that the [O I], [Si II], and high-J CO emission emanates solely from the clumps, while the [C II], [C I], and low-J CO emission arises primarily in the interclump gas. The halo is necessary to produce the very extended [C II] and [C I]. In conclusion, we stress that the M17SW PDR encompasses a wide range of physical conditions and that the individual cooling lines emanate from the regions where their excitation conditions are best met. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP MEIXNER, M (reprint author), UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720, USA. NR 56 TC 97 Z9 97 U1 2 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1992 VL 390 IS 2 BP 499 EP 513 DI 10.1086/171301 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HR232 UT WOS:A1992HR23200021 ER PT J AU VERSCHUUR, GL RICKARD, LJ VERTER, F POUND, MW LEISAWITZ, D AF VERSCHUUR, GL RICKARD, LJ VERTER, F POUND, MW LEISAWITZ, D TI THE SEPARATION BETWEEN GAS AND DUST FILAMENTS AT THE EDGE OF THE EXPANDING SHELL IN ERIDANUS SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; ISM-INDIVIDUAL (ERIDANUS); RADIO LINES-ATOMIC ID HIGH GALACTIC LATITUDES; H-ALPHA FILAMENTS; INTERSTELLAR GRAINS; INFRARED-EMISSION; MOLECULAR CLOUDS; GALAXY; SCALE; ASSOCIATION; EXTINCTION; DIRECTIONS AB Adjacent filaments of ionized hydrogen, neutral hydrogen, and dust cross a 120 square degree region around l = 187-degrees, b = -50-degrees, at the boundary of a large expanding shell in Eridanus. The dust is visible on the IRAS Sky Flux Plates and looks like typical "interstellar cirrus." The morphology observed in H I emission is very similar, but with associated structures offset in position by amounts that vary across the region. The H I and IR filaments are approximately 1-degree wide and are offset by up to 0.8-degrees. All of the separation measurements have confidence levels of 95% or more. The H I and IR filaments are separated from parallel H-alpha filaments by 3-degrees-4-degrees. For the H I and IR emission in this region of the sky, a point-by-point comparison yields a very weak correlation between I(100) and N(HI); however, when I(100) at a dust feature is compared to N(H I) at the associated (offset) H I feature, a relationship close to that reported by other workers is revealed. Specifically, the nature of the separation between gas and dust is that the primary H I filament is deficient in dust by an order of magnitude, whereas the corresponding dust filament has sufficient gas to reproduce the dust/gas mass ratio approximately 1 x 10(-3) that is expected for cirrus. Observations of CO emission from this region show that the separation between the structures in the H I and IR emission is not due to a transition of the gas into molecular hydrogen at the location of the IR filaments. Indeed, the molecular hydrogen column density of these filaments is at least two orders of magnitude below what is typically seen in high-latitude molecular clouds. As the H I and dust in this region are associated with a large expanding shell (or superbubble), the action of shocks and radiation fields may be responsible for the separation of gas and dust. Such shells are believed to be common in the Galaxy, and therefore similar separations of gas and dust at other shell boundaries may be expected. Unless the gas and dust structures are resolved and lie in a favorable viewing geometry, the effect would tend to be hidden. Our results emphasize that it is not always evident, from observations with spatial resolutions coarser than a few arcminutes, how interstellar gas and dust are related. C1 USN,RES LAB,CTR ADV SPACE SENSING,WASHINGTON,DC 20375. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. AT&T BELL LABS,MURRAY HILL,NJ 07974. RI Pound, Marc/A-1600-2010 NR 51 TC 18 Z9 18 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1992 VL 390 IS 2 BP 514 EP & DI 10.1086/171302 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HR232 UT WOS:A1992HR23200022 ER PT J AU LEROUX, JA POTGIETER, MS AF LEROUX, JA POTGIETER, MS TI THE SIMULATED FEATURES OF HELIOSPHERIC COSMIC-RAY MODULATION WITH A TIME-DEPENDENT DRIFT MODEL .2. ON THE ENERGY-DEPENDENCE OF THE ONSET OF NEW MODULATION IN 1987 SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC RAYS; SUN-PARTICLE EMISSION ID NEUTRAL SHEET DRIFT; SOLAR MODULATION; MAGNETIC-FIELD; LATITUDE; CYCLE AB A time-dependent axially symmetric drift model with an emulated wavy heliospheric neutral sheet (HNS) is used to simulate time-dependent modulation for the period 1985-1989. In the first of this series of papers we showed very realistic intensity-time profiles for 1 GeV protons for this period. We illustrated that the observed time delays in the time of minimum modulation with increasing radial distances in 1987 could be simulated with our model. Radial and latitudinal gradients for these protons were found markedly compatible with observations. For this paper the same model is used to extend our calculations to other energies in order to study a possible energy-dependence of the onset of new modulation at various radial distances in 1987. It is found that the model, with the outward propagating changes of the HNS as the only time-dependent parameter, predicts essentially no energy-dependence in the time when new modulation started in the simulated 1987. However, when a more practical approach in defining " constant " modulation in 1987 is followed, our calculations can be interpreted to indicate that the end of the recovery period in 1987 happened progressively earlier and the onset of new modulation progressively later the higher the rigidity of the cosmic rays. This period of relatively unchanged modulation is predicted to last longer with increasing radial distance. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP LEROUX, JA (reprint author), UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLLEGE PK,MD 20742, USA. NR 25 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1992 VL 390 IS 2 BP 661 EP 667 DI 10.1086/171317 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HR232 UT WOS:A1992HR23200037 ER PT J AU MULCHAEY, JS MUSHOTZKY, RF WEAVER, KA AF MULCHAEY, JS MUSHOTZKY, RF WEAVER, KA TI HARD X-RAY TESTS OF THE UNIFIED MODEL FOR AN ULTRAVIOLET-DETECTED SAMPLE OF SEYFERT-2 GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, NUCLEI; GALAXIES, SEYFERT; ULTRAVIOLET, GALAXIES; X-RAYS, GALAXIES ID EMISSION; SPECTROPOLARIMETRY; ABSORPTION; NGC-1068 AB A ultraviolet-detected sample of Seyfert 2 galaxies shows heavy photoelectric absorption in the hard X-ray band. The presence of UV emission combined with hard X-ray absorption argues strongly for a special geometry which must have the general properties of the Antonucci & Miller unified model. The observations of this sample are consistent with the picture in which the hard X-ray photons are viewed directly through the obscuring matter (molecular torus?) and the optical, UV, and soft X-ray continuum are seen in scattered light. The large range in X-ray column densities implies that there must be a large variation in intrinsic thicknesses of molecular tori, an assumption not found in the simplest of unified models. Furthermore, constraints based on the cosmic X-ray background suggest that some of the underlying assumptions of the unified model are wrong. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP MULCHAEY, JS (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. NR 32 TC 67 Z9 67 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1992 VL 390 IS 2 BP L69 EP L72 DI 10.1086/186374 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HR233 UT WOS:A1992HR23300007 ER PT J AU STECKER, FW DEJAGER, OC SALAMON, MH AF STECKER, FW DEJAGER, OC SALAMON, MH TI TEV GAMMA-RAYS FROM 3C-279 - A POSSIBLE PROBE OF ORIGIN AND INTERGALACTIC INFRARED RADIATION-FIELDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, THEORY; INFRARED, GENERAL; QUASARS, GENERAL; QUASARS, INDIVIDUAL (3C-279) ID ACTIVE GALACTIC NUCLEI; RELATIVISTIC JETS; PAIR PRODUCTION; EMISSION; ACCELERATION AB The gamma-ray spectrum of 3C 279 during 1991 June exhibited a near perfect power law between 50 MeV and over 5 GeV with a differential spectral index of -(2.02 +/- 0.07). If extrapolated, the gamma-ray spectrum of 3C 279 should be easily detectable with first generation air Cerenkov detectors operating above approximately 0.3 TeV, provided there is no intergalactic absorption. However, by using model-dependent lower and upper limits for the extra-galactic infrared background radiation field, we predict a sharp cutoff of the 3C 279 spectrum between approximately 0.1 and approximately 1 TeV. The sensitivity of present air Cerenkov detectors is good enough to measure such a cutoff, which would provide the first opportunity to obtain a measurement of, or at least a severe constraint on the extragalactic background infrared radiation field. C1 UNIV UTAH,DEPT PHYS,SALT LAKE CITY,UT 84112. RP STECKER, FW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 665,GREENBELT,MD 20771, USA. RI Stecker, Floyd/D-3169-2012 NR 30 TC 229 Z9 229 U1 1 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 10 PY 1992 VL 390 IS 2 BP L49 EP L52 DI 10.1086/186369 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HR233 UT WOS:A1992HR23300002 ER PT J AU PONTON, MK SEINER, JM AF PONTON, MK SEINER, JM TI THE EFFECTS OF NOZZLE EXIT LIP THICKNESS ON PLUME RESONANCE SO JOURNAL OF SOUND AND VIBRATION LA English DT Article ID SCREECH RP PONTON, MK (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 15 TC 45 Z9 48 U1 0 U2 0 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0022-460X J9 J SOUND VIB JI J. Sound Vibr. PD MAY 8 PY 1992 VL 154 IS 3 BP 531 EP 549 DI 10.1016/0022-460X(92)90784-U PG 19 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA HU518 UT WOS:A1992HU51800011 ER PT J AU FOROUHAR, S LARSSON, A KSENDZOV, A LANG, RJ TOTHILL, N SCOTT, MD AF FOROUHAR, S LARSSON, A KSENDZOV, A LANG, RJ TOTHILL, N SCOTT, MD TI ROOM-TEMPERATURE OPERATION OF MOCVD-GROWN GAINAS/INP STRAINED-LAYER MULTIQUANTUM WELL LASERS IN 1-BULLET-8-MU-M RANGE SO ELECTRONICS LETTERS LA English DT Article DE SEMICONDUCTOR LASERS; LASERS AB The first successful room-temperature pulsed operation is reported of InGaAs strained layer multiquantum well (SL-MQW) injection lasers grown by MOVPE on InP substrates in the 1.8-mu-m range. The threshold current density and the external differential quantum efficiency of the 10-mu-m wide ridge waveguide lasers were 2.5kA/cm2 (cavity length = 1mm) and 5% (cavity length = 400-mu-m), respectively. Broad-area lasers, 100-mu-m wide and 1 mm long, had a reverse leakage current of less than 10-mu-A at -1V indicating high quality of the epitaxial layers. C1 EPITAXIAL PROD INT LTD,CARDIFF,WALES. RP FOROUHAR, S (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 9 TC 13 Z9 14 U1 0 U2 1 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD MAY 7 PY 1992 VL 28 IS 10 BP 945 EP 947 DI 10.1049/el:19920599 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA HU156 UT WOS:A1992HU15600031 ER PT J AU LINDQWISTER, UJ FREEDMAN, AP BLEWITT, G AF LINDQWISTER, UJ FREEDMAN, AP BLEWITT, G TI DAILY ESTIMATES OF THE EARTHS POLE POSITION WITH THE GLOBAL POSITIONING SYSTEM SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Daily estimates of the Earth's pole position have been obtained with measurements from a worldwide network of Global Positioning System (GPS) receivers, obtained during the three week GIG'91 experiment in January-February, 1991. For this short-term study, the GPS based polar motion series agrees with the other space, based geodetic techniques (Very Long Baseline Interferometry and Satellite Laser Ranging) to approximately 0.4 mas rms, after the removal of mean biases of order 1-3 mas. The small error in day-to-day variability is not sensitive to the fiducial strategy used, nor are fiducial sites even necessary for monitoring high frequency pole position variability. The small biases indicate that the applied reference frames of the three geodetic techniques are nearly aligned, that the GPS fiducial errors are small, and that systematic errors in GPS are also small (of order 5 ppb). A well determined reference frame is necessary for monitoring the long-term stability of polar motion and for separating it from other long-term signals such as tectonic motion and internal systematic errors. RP LINDQWISTER, UJ (reprint author), CALTECH,JET PROP LAB,MS 238624,PASADENA,CA 91109, USA. NR 13 TC 11 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 4 PY 1992 VL 19 IS 9 BP 845 EP 848 DI 10.1029/92GL00576 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HT894 UT WOS:A1992HT89400001 ER PT J AU GROSS, RS LINDQWISTER, UJ AF GROSS, RS LINDQWISTER, UJ TI ATMOSPHERIC EXCITATION OF POLAR MOTION DURING THE GIG-91 MEASUREMENT CAMPAIGN SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Daily determinations of the Earth's pole position from Global Positioning System (GPS) observations acquired during the first GPS IERS and Geodynamics (GIG) experiment held during January 22, 1991 to February 13, 1991 are interpreted in terms of atmospheric wind and pressure fluctuations as parameterized by the atmospheric angular momentum (AAM) chi-functions. All available AAM chi-functions spanning the GIG '91 period have been collected and compared to the observations in the time and polar motion domains. The greatest level of agreement is obtained using die total (wind plus pressure) chi-functions from the Japanese Meteorological Agency (JMA) where the pressure term is computed by assuming the inverted barometer approximation. In this case, the correlation coefficient between the observed and JMA-induced polar motion series is 0.91 for the x-component and 0.72 for the y-component, the rms of the difference between the observed and JMA-induced series is 0.71 mas for the x-component and 0.69 mas for the y-component, and the percentage of the variance of the observed series explained by the JMA-induced series is 83% for the x-component and 48% for the y-component. Thus, it is demonstrated that atmospheric wind and pressure fluctuations are largely responsible for exciting the rapid polar motions observed during GIG '91. RP GROSS, RS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 28 Z9 29 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 4 PY 1992 VL 19 IS 9 BP 849 EP 852 DI 10.1029/92GL00935 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HT894 UT WOS:A1992HT89400002 ER PT J AU BLEWITT, G HEFLIN, MB WEBB, FH LINDQWISTER, UJ MALLA, RP AF BLEWITT, G HEFLIN, MB WEBB, FH LINDQWISTER, UJ MALLA, RP TI GLOBAL COORDINATES WITH CENTIMETER ACCURACY IN THE INTERNATIONAL TERRESTRIAL REFERENCE FRAME USING GPS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Using 21 days of Global Positioning System (GPS) data from 21 globally distributed receivers operating during early 1991, we solve for a 7-parameter transformation between a GPS free-network solution and coordinates of 12 stations listed in the International Terrestrial Reference Frame (ITRF). Standard errors of GPS coordinates are derived by applying an orthogonal projection operator to the free-network covariance. The weighted RMS difference between 33 transformed GPS and ITRF coordinates is 12 mm in the northern hemisphere. Best results are obtained by mapping ITRF coordinates to the epoch of this experiment assuming no vertical site motions. Fixing selected sites in the GPS solution to ITRF'90 does not improve the agreement. We conclude the use of fiducial constraints is unnecessary for global networks. RP BLEWITT, G (reprint author), CALTECH,JET PROP LAB,MAIL STOP 238-625,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 TC 59 Z9 61 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAY 4 PY 1992 VL 19 IS 9 BP 853 EP 856 DI 10.1029/92GL00775 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HT894 UT WOS:A1992HT89400003 ER PT J AU LANDIS, GA AF LANDIS, GA TI REACTIONLESS ORBITAL PROPULSION USING TETHER DEPLOYMENT SO ACTA ASTRONAUTICA LA English DT Article AB A satellite in orbit can propel itself by retracting and deploying a length of tether, with expenditure of energy but with no use of on-board reaction mass, as shown by Landis and Hrach in a previous paper. The orbit can be raised, lowered, or the orbital position changed, by reaction against the gravitational gradient. Energy is added to or removed from the orbit by pumping the tether length in the same way as pumping a swing. Examples of tether propulsion in orbit without use of reaction mass are discussed, including: (1) using tether extension to reposition a satellite in orbit without fuel expenditure by extending a mass on the end of a tether; (2) using a tether for eccentricity pumping to add energy to the orbit for boosting and orbital transfer; and (3) length modulation of a spinning tether to transfer angular momentum between the orbit and tether spin, thus allowing changes in orbital angular momentum. RP LANDIS, GA (reprint author), NASA,LEWIS RES CTR,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 0 TC 23 Z9 23 U1 2 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAY PY 1992 VL 26 IS 5 BP 307 EP 312 DI 10.1016/0094-5765(92)90076-U PG 6 WC Engineering, Aerospace SC Engineering GA JH491 UT WOS:A1992JH49100002 ER PT J AU LEI, JF AF LEI, JF TI PD-CR GAUGES MEASURE STATIC STRAIN AT HIGH-TEMPERATURES SO ADVANCED MATERIALS & PROCESSES LA English DT Article RP LEI, JF (reprint author), SVERDRUP TECHNOL INC,NASA LEWIS RES CTR GRP,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 SN 0026-0665 J9 ADV MATER PROCESS JI Adv. Mater. Process. PD MAY PY 1992 VL 141 IS 5 BP 58 EP 59 PG 2 WC Materials Science, Multidisciplinary SC Materials Science GA HT821 UT WOS:A1992HT82100007 ER PT J AU ATKINS, HL AF ATKINS, HL TI EVALUATION OF A FINITE VOLUME METHOD FOR COMPRESSIBLE SHEAR LAYERS SO AIAA JOURNAL LA English DT Article AB An implicit second-order finite volume method for solving the compressible laminar Navier-Stokes equations in two dimensions is evaluated for possible use in the simulation of transitional flows. Comparisons are made with results from a spectral linear-stability code, which provides accurate growth rates, as well as perturbation eigenfunctions, for a temporally growing free shear layer. The accuracy of the growth rates of isolated modes and the physical and numerical interactions of multiple modes is the focus of this study. A grid refinement study verified the method to be second-order accurate with less than 4% error on a 32 x 64 grid. The interaction between modes of similar amplitude was small (less than 1%). In cases where there was a dominant mode, however, numerical phase error in the method pumped energy into all other modes. This numerical phase error results in nonphysical growth rates for modes whose amplitude content is several orders of magnitude below the dominant mode. When the dominant mode saturates, the pumping action ceases, and the growth rate of the next largest growing mode regains physical significance. RP ATKINS, HL (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1992 VL 30 IS 5 BP 1214 EP 1219 DI 10.2514/3.11053 PG 6 WC Engineering, Aerospace SC Engineering GA HT594 UT WOS:A1992HT59400009 ER PT J AU RAUSCH, RD BATINA, JT YANG, HTY AF RAUSCH, RD BATINA, JT YANG, HTY TI SPATIAL ADAPTATION OF UNSTRUCTURED MESHES FOR UNSTEADY AERODYNAMIC FLOW COMPUTATIONS SO AIAA JOURNAL LA English DT Article AB Spatial adaptation procedures for the accurate and efficient solution of steady and unsteady inviscid flow problems are described. The adaptation procedures were developed and implemented within a two-dimensional unstructured-grid upwind-type Euler code. These procedures involve mesh enrichment and mesh coarsening to either add points in high gradient regions of the flow or remove points where they are not needed, respectively, to produce solutions of high spatial accuracy at minimal computational cost. The paper describes a new approach to detect high gradient regions of the flow that uses the substantial derivative of density. Additionally, the paper gives a detailed description of the enrichment and coarsening procedures and further describes a new weighted averaging procedure and the interpolation of flow variables that improves the overall accuracy of the flow solver. Presented are comparisons with alternative results and experimental data to provide an assessment of the accuracy and efficiency of the capability. Steady and unsteady transonic results, obtained using spatial adaptation for the NACA 0012 airfoil, are shown to be of high spatial accuracy, primarily in that the shock waves are very sharply captured. The results were obtained with large computational savings when compared to results for a globally enriched mesh with cells subdivided as many times as the finest cells of the adapted grid. C1 NASA,LANGLEY RES CTR,UNSTEADY AERODYNAM BRANCH,DIV STRUCT DYNAM,HAMPTON,VA 23665. PURDUE UNIV,SCH ENGN,W LAFAYETTE,IN 47907. RP RAUSCH, RD (reprint author), PURDUE UNIV,SCH AERONAUT & ASTRONAUT,W LAFAYETTE,IN 47907, USA. NR 23 TC 31 Z9 32 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1992 VL 30 IS 5 BP 1243 EP 1251 DI 10.2514/3.11057 PG 9 WC Engineering, Aerospace SC Engineering GA HT594 UT WOS:A1992HT59400013 ER PT J AU THANGAM, S SPEZIALE, CG AF THANGAM, S SPEZIALE, CG TI TURBULENT-FLOW PAST A BACKWARD-FACING STEP - A CRITICAL-EVALUATION OF 2-EQUATION MODELS SO AIAA JOURNAL LA English DT Article ID STRESS AB The ability of two-equation turbulence models to accurately predict separated flows is analyzed from a combined theoretical and computational standpoint. Turbulent flow past a backward-facing step is chosen as a test case in an effort to resolve the various conflicting results that have been published during the past decade concerning the performance of two-equation models. The results obtained demonstrate that errors in the reported predictions of the K-epsilon model have two major origins: 1) numerical problems arising from inadequate resolution, and 2) inaccurate predictions for normal Reynolds stress differences arising from the use of an isotropic eddy viscosity. Inadequacies in near-wall modeling play a substantially smaller role. Detailed calculations are presented that strongly indicate that the standard K-epsilon model-when modified with an independently calibrated anisotropic eddy viscosity-can yield surprisingly good predictions for the back-step problem. C1 STEVENS INST TECHNOL LIB,DEPT MECH ENGN,HOBOKEN,NJ 07030. RP THANGAM, S (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665, USA. NR 29 TC 64 Z9 71 U1 0 U2 7 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1992 VL 30 IS 5 BP 1314 EP 1320 DI 10.2514/3.11066 PG 7 WC Engineering, Aerospace SC Engineering GA HT594 UT WOS:A1992HT59400022 ER PT J AU LIBRESCU, L STEIN, M AF LIBRESCU, L STEIN, M TI POSTBUCKLING OF SHEAR DEFORMABLE COMPOSITE FLAT PANELS TAKING INTO ACCOUNT GEOMETRICAL IMPERFECTIONS SO AIAA JOURNAL LA English DT Article ID LAMINATED SHELLS; REFINED THEORIES; PLATES AB The postbuckling behavior of composite flat panels subjected to uniaxial/biaxial compressive loads is investigated. To this end a refined geometrically nonlinear theory of composite plates is developed. The effects played by transverse shear deformation, initial geometric imperfections, the character of the in-plane boundary conditions and lamination are studied and a series of pertinent conclusions are outlined. Throughout the paper, the results obtained within the transverse shear deformable plate model are compared with their classical counterparts and conclusions related to their range of applicability are presented. C1 NASA,LANGLEY RES CTR,STRUCT MECH BRANCH,DIV STRUCT & DYNAM,HAMPTON,VA 23665. RP LIBRESCU, L (reprint author), VIRGINIA POLYTECH INST & STATE UNIV,DEPT ENGN SCI & MECH,BLACKSBURG,VA 24061, USA. NR 31 TC 34 Z9 34 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1992 VL 30 IS 5 BP 1352 EP 1360 DI 10.2514/3.11071 PG 9 WC Engineering, Aerospace SC Engineering GA HT594 UT WOS:A1992HT59400027 ER PT J AU SHEN, MHH GRADY, JE AF SHEN, MHH GRADY, JE TI FREE-VIBRATIONS OF DELAMINATED BEAMS SO AIAA JOURNAL LA English DT Article ID COMPOSITE AB Free vibration of laminated composite beams is studied. The effect of interply delaminations on natural frequencies and mode shapes is evaluated both analytically and experimentally. A generalized variational principle is used to formulate the equation of motion and associated boundary conditions for the free vibration of a composite beam with a delamination of arbitrary size and location. The effect of coupling between longitudinal vibration and bending vibration is considered. This coupling effect is shown to significantly effect the calculated natural frequencies and mode shapes of the delaminated beam. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SHEN, MHH (reprint author), OHIO STATE UNIV,DEPT AERONAUT & ASTRONAUT,COLUMBUS,OH 43210, USA. NR 22 TC 169 Z9 172 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1992 VL 30 IS 5 BP 1361 EP 1370 DI 10.2514/3.11072 PG 10 WC Engineering, Aerospace SC Engineering GA HT594 UT WOS:A1992HT59400028 ER PT J AU LAKE, MS KLANG, EC AF LAKE, MS KLANG, EC TI GENERATION AND COMPARISON OF GLOBALLY ISOTROPIC SPACE-FILLING TRUSS STRUCTURES SO AIAA JOURNAL LA English DT Article AB The purposes of this paper are to present a rationale for obtaining space-filling truss structures that behave like a globally isotropic continuum and to use continuum modeling to investigate their relative structural efficiencies (e.g., modulus-to-density, strength-to-density, and part-count-to-volume ratios). The trusses considered herein are generated by replication of a characteristic truss cell uniformly through space. The characteristic cells are categorized by one of a set of possible geometric symmetry groups derived using the techniques of crystallography. The implied elastic symmetry associated with each geometric symmetry group is identified to simplify the task of determining stiffness tailoring rules for guaranteeing global isotropy. Four truss geometries are analyzed to determine stiffness tailoring necessary for isotropy. All geometries exhibit equivalent isotropic Poisson's ratios of 1/4 and equivalent modulus-to-density ratios of 1/6 times the modulus-to-density ratio of the material used in their members. The truss configuration that has the lowest percent difference in member lengths is shown to have the lowest component part-count-to-volume ratios of all geometries considered when compared on a basis of equal stiffness, equal strength, and equal mass. C1 N CAROLINA STATE UNIV,DEPT MECH & AEROSP ENGN,RALEIGH,NC 27695. RP LAKE, MS (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT MECH,HAMPTON,VA 23665, USA. NR 10 TC 9 Z9 9 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1992 VL 30 IS 5 BP 1416 EP 1424 DI 10.2514/3.11078 PG 9 WC Engineering, Aerospace SC Engineering GA HT594 UT WOS:A1992HT59400034 ER PT J AU MOITRA, A AF MOITRA, A TI 2-DIMENSIONAL AND 3-DIMENSIONAL GRID GENERATION BY AN ALGEBRAIC HOMOTOPY PROCEDURE SO AIAA JOURNAL LA English DT Note RP MOITRA, A (reprint author), NASA,LANGLEY RES CTR,HIGH TECHNOL CORP,MAIL STOP 128,HAMPTON,VA 23665, USA. NR 3 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAY PY 1992 VL 30 IS 5 BP 1433 EP 1434 DI 10.2514/3.11080 PG 2 WC Engineering, Aerospace SC Engineering GA HT594 UT WOS:A1992HT59400036 ER PT J AU CHAFFIN, DB WOLDSTAD, JC TRUJILLO, A AF CHAFFIN, DB WOLDSTAD, JC TRUJILLO, A TI FLOOR SHOE SLIP RESISTANCE MEASUREMENT SO AMERICAN INDUSTRIAL HYGIENE ASSOCIATION JOURNAL LA English DT Article ID FRICTION AB A variety of slip measurement devices exist that provide estimates of both static and dynamic coefficient-of-friction (COF) values between one's shoes and the floor. Unfortunately, different shoe sole/heel materials, floor conditions, and contaminants will affect the tests in ways that result in widely varying COF estimates. This paper reviews the basic physics of such tests and describes a set of experiments to determine the static- and dynamic COF values under operating conditions known to exist in different jobs. The results define a set of conditions wherein low, (hazardous) COF values would exist (e.g., hard Neolite(TM) shoe material in contact with a wet, smooth walking surface). The results also question the use of light-load testing devices and static and slow speed reference COF values in the literature. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. VIRGINIA POLYTECH INST & STATE UNIV,BLACKSBURG,VA 24061. RP CHAFFIN, DB (reprint author), UNIV MICHIGAN,CTR ERGON,ANN ARBOR,MI 48109, USA. FU NIOSH CDC HHS [T15-OHO7207-07] NR 25 TC 23 Z9 24 U1 0 U2 2 PU AMER INDUSTRIAL HYGIENE ASSOC PI FAIRFAX PA 2700 PROSPERITY AVE #250, FAIRFAX, VA 22031-4307 SN 0002-8894 J9 AM IND HYG ASSOC J JI Am. Ind. Hyg. Assoc. J. PD MAY PY 1992 VL 53 IS 5 BP 283 EP 289 DI 10.1202/0002-8894(1992)053<0283:FSRM>2.0.CO;2 PG 7 WC Environmental Sciences; Public, Environmental & Occupational Health SC Environmental Sciences & Ecology; Public, Environmental & Occupational Health GA JK339 UT WOS:A1992JK33900003 PM 1609738 ER PT J AU OU, YR BURNS, JA AF OU, YR BURNS, JA TI OPTIMAL-CONTROL OF LIFT/DRAG RATIOS ON A ROTATING CYLINDER SO APPLIED MATHEMATICS LETTERS LA English DT Article ID CIRCULAR-CYLINDER; SYSTEMS AB We present the numerical solution to a problem of maximizing the lift to drag ratio by rotating a circular cylinder in a two-dimensional viscous incompressible flow. This problem is viewed as a test case for the newly developing theoretical and computational methods for control of fluid dynamic systems. We show that the time averaged lift to drag ratio for a fixed finite-time interval achieves its maximum value at an optimal rotation rate that depends on the time interval. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. VIRGINIA POLYTECH INST & STATE UNIV,INTERDISCIPLINARY CTR APPL MATH,BLACKSBURG,VA 24061. NR 11 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0893-9659 J9 APPL MATH LETT JI Appl. Math. Lett. PD MAY PY 1992 VL 5 IS 3 BP 57 EP 62 DI 10.1016/0893-9659(92)90040-G PG 6 WC Mathematics, Applied SC Mathematics GA HT590 UT WOS:A1992HT59000015 ER PT J AU THOMPSON, CP LEAF, GK VANROSENDALE, J AF THOMPSON, CP LEAF, GK VANROSENDALE, J TI A DYNAMICALLY ADAPTIVE MULTIGRID ALGORITHM FOR THE INCOMPRESSIBLE NAVIER-STOKES EQUATIONS - VALIDATION AND MODEL PROBLEMS SO APPLIED NUMERICAL MATHEMATICS LA English DT Article ID FLOWS AB We describe an algorithm for the solution of the laminar, incompressible Navier-Stokes equations. The basic algorithm is a multigrid method based on a robust, box-based smoothing step. Its most important feature is the incorporation of automatic, dynamic mesh refinement. Using an approximation to the local truncation error to control the refinement, we use a form of domain decomposition to introduce patches of finer grid wherever they are needed to ensure an accurate solution. This refinement strategy is completely local: regions that satisfy our tolerance are unmodified, except when they must be refined to maintain reasonable mesh ratios. This locality has the important consequence that boundary layers and other regions of sharp transition do not "steal" mesh points from surrounding regions of smooth flow, in contrast to moving mesh strategies where such "stealing" is inevitable. Our algorithm supports generalized simple domains, that is, any domain defined by horizontal and vertical lines. This generality is a natural consequence of our domain decomposition approach. We base our program on a standard staggered-grid formulation of the Navier-Stokes equations for robustness and efficiency. To ensure discrete mass conservation, we have introduced special grid transfer operators at grid interfaces in the multigrid algorithm. While these operators complicate the algorithm somewhat, our approach results in exact mass conservation and rapid convergence. In this paper, we present results for three model problems: the driven cavity, a backward-facing step, and a sudden expansion/contraction. Our approach obtains convergence rates that are independent of grid size and that compare favorably with other multigrid algorithms. We also compare the accuracy of our results with other benchmark results. C1 ARGONNE NATL LAB,DIV MATH & COMP SCI,ARGONNE,IL 60439. NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP THOMPSON, CP (reprint author), IBM CORP,BERGEN SCI CTR,THORMOHLENSGATE 55,N-5008 BERGEN,NORWAY. OI Thompson, Christopher/0000-0003-1939-6749 NR 18 TC 3 Z9 4 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9274 J9 APPL NUMER MATH JI Appl. Numer. Math. PD MAY PY 1992 VL 9 IS 6 BP 511 EP 532 DI 10.1016/0168-9274(92)90005-X PG 22 WC Mathematics, Applied SC Mathematics GA HQ512 UT WOS:A1992HQ51200005 ER PT J AU CHIPMAN, RA BROWN, DM MCGUIRE, JP AF CHIPMAN, RA BROWN, DM MCGUIRE, JP TI POLARIZATION ABERRATION ANALYSIS OF THE ADVANCED X-RAY ASTROPHYSICS FACILITY TELESCOPE ASSEMBLY SO APPLIED OPTICS LA English DT Article DE X-RAY OPTICS; POLARIZATION; ABERRATIONS; IMAGE FORMATION; POINT-SPREAD FUNCTION; POLARIMETRY; REFLECTION; TELESCOPES; APODIZATION; DEPOLARIZERS; GRAZING-INCIDENCE OPTICS ID OPTICAL-CONSTANTS; I TELESCOPE; THIN-FILMS; SYSTEMS; 1216-A; 24-A AB The advanced x-ray astrophysics facility (AXAF) telescope consists of six concentric paraboloid-hyperboloid pairs of mirrors that operate near grazing incidence. Because of the substantial polarization effects at large angles of incidence there has been concern regarding the feasibility of doing polarimetry near the telescope focal plane. The primary mirror is shown to act as a tangentially directed half-wave linear retarder and to almost completely depolarize the linearly polarized component of the light. The secondary mirror introduces an additional half-wave of linear retardance. The two-mirror telescope assembly acts as a tangentially directed one-wave linear retarder. Each mirror depolarizes alone but together the two-mirror assembly preserves the polarization state. The net instrumental polarization effects are small and polarimetry is feasible with AXAF. The polarization aberration function for the telescope is derived by using Jones calculus. Polarization aberration functions are used to calculate the effect of instrumental polarization on the transmitted wave front and the polarization state that is due to the primary mirror and the telescope assembly. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP CHIPMAN, RA (reprint author), UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899, USA. NR 27 TC 9 Z9 9 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAY 1 PY 1992 VL 31 IS 13 BP 2301 EP 2313 PG 13 WC Optics SC Optics GA HR028 UT WOS:A1992HR02800021 PM 20720894 ER PT J AU WELTY, AD BARDEN, SC HUENEMOERDER, DP RAMSEY, LW AF WELTY, AD BARDEN, SC HUENEMOERDER, DP RAMSEY, LW TI BF-ORIONIS - EVIDENCE FOR AN INFALLING CIRCUMSTELLAR ENVELOPE SO ASTRONOMICAL JOURNAL LA English DT Article ID LYNDS-1641 DARK CLOUD; MAIN-SEQUENCE STARS; T-TAURI STARS; STELLAR POPULATION; VARIABILITY; ACCRETION; CATALOG AB Analysis of the optical magnitudes and Balmer lines of the Herbig Ae/Be star BF Orionis confirm that the object is an early to mid A-type star, but appears to be below the zero-age main sequence. Enhanced metal line strengths (once thought to link BF Ori with the Am stars), line asymmetries, and radial velocities are shown to be signatures of an infalling circumstellar envelope. We investigate the possibility that BF Ori may have a late type companion, and conclude that it does not. C1 KITT PEAK NATL OBSERV,TUCSON,AZ 85726. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP WELTY, AD (reprint author), PENN STATE UNIV,DEPT ASTRON & ASTROPHYS,525 DAVEY LAB,UNIV PK,PA 16802, USA. NR 38 TC 18 Z9 18 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD MAY PY 1992 VL 103 IS 5 BP 1673 EP 1678 DI 10.1086/116184 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HR195 UT WOS:A1992HR19500029 ER PT J AU KOVALEVSKY, J FALIN, JL PIEPLU, JL BERNACCA, PL DONATI, F FROESCHLE, M GALLIGANI, I MIGNARD, F MORANDO, B PERRYMAN, MAC SCHRIJVER, H VANDAALEN, DT VANDERMAREL, H VILLENAVE, M WALTER, HG BADIALI, M BORRIELLO, L BROUW, WN CANUTO, E GUERRY, A HERING, R HUC, C IORIOFILI, D LACROUTE, P LATTANZI, M LEPOOLE, RS MURGOLO, FP PRESTON, RA ROSER, S SANSO, F WIELEN, R BELFORTE, P BERNSTEIN, HH BUCCIARELLI, B CARDINI, D EMANUELE, A FASSINO, B LENHART, H LESTRADE, JF PREZIOSO, G MONTANARI, TT AF KOVALEVSKY, J FALIN, JL PIEPLU, JL BERNACCA, PL DONATI, F FROESCHLE, M GALLIGANI, I MIGNARD, F MORANDO, B PERRYMAN, MAC SCHRIJVER, H VANDAALEN, DT VANDERMAREL, H VILLENAVE, M WALTER, HG BADIALI, M BORRIELLO, L BROUW, WN CANUTO, E GUERRY, A HERING, R HUC, C IORIOFILI, D LACROUTE, P LATTANZI, M LEPOOLE, RS MURGOLO, FP PRESTON, RA ROSER, S SANSO, F WIELEN, R BELFORTE, P BERNSTEIN, HH BUCCIARELLI, B CARDINI, D EMANUELE, A FASSINO, B LENHART, H LESTRADE, JF PREZIOSO, G MONTANARI, TT TI THE FAST HIPPARCOS-DATA-REDUCTION-CONSORTIUM - OVERVIEW OF THE REDUCTION SOFTWARE SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE HIPPARCOS; DATA ANALYSIS; ASTROMETRY; PHOTOMETRY AB This paper gives the main features of the data analysis methods adopted by FAST in the calibration and processing of the Hipparcos data. The structure of the data reduction software is described and the actual processing and evaluation is presented. C1 CTR NATL ETUD SPATIALES, F-31055 TOULOUSE, FRANCE. OSSERVATORIO ASTROFIS, DIPARTIMENTO ASTRON, I-36012 VICENZA, ITALY. CTR STUDI SISTEMI, I-10128 TURIN, ITALY. DIPARTIMENTO MATEMAT, I-40126 BOLOGNA, ITALY. BUR LONGITUDES, F-75014 PARIS, FRANCE. EUROPEAN SPACE AGCY, EUROPEAN SPACE RES & TECHNOL CTR, DIV ASTROPHYS, 2200 AG NOORDWIJK, NETHERLANDS. LAB SPACE RES, 3584 CA UTRECHT, NETHERLANDS. DELFT UNIV TECHNOL, FAC GEODESY, 2629 JA DELFT, NETHERLANDS. ASTRON RECH INST, W-6900 HEIDELBERG, GERMANY. IST ASTROFIS SPAZIALE, I-00044 FRASCATI, ITALY. CSATA, I-70010 VALENZANO, ITALY. NETHERLANDS FDN RES ASTRON, 7990 AA DWINGELOO, NETHERLANDS. IST NAZL OTTICA, I-50125 FLORENCE, ITALY. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. STERREWACHT LEIDEN, 2300 RA LEIDEN, NETHERLANDS. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. IST TOPOG FOTOGRAMMETRIA & GEOFIS, I-20133 MILAN, ITALY. RP KOVALEVSKY, J (reprint author), CTR ETUD & RECH GEODYNAM & ASTRON, OBSERV COTE AZUR, F-06130 GRASSE, FRANCE. NR 51 TC 42 Z9 42 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 MAY PY 1992 VL 258 IS 1 BP 7 EP 17 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HQ508 UT WOS:A1992HQ50800002 ER PT J AU LESTRADE, JF PHILLIPS, RB PRESTON, RA GABUZDA, DC AF LESTRADE, JF PHILLIPS, RB PRESTON, RA GABUZDA, DC TI HIGH-PRECISION VLBI ASTROMETRY OF THE RADIO-EMITTING STAR-SIGMA CRB - A STEP IN LINKING THE HIPPARCOS AND EXTRAGALACTIC REFERENCE FRAMES SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE VLBI; HIPPARCOS; ASTROMETRY; REFERENCE SYSTEMS ID EMISSION; POSITION AB VLBI observations of the optically bright radio-emitting star sigma-Coronae Borealis (sigma-CrB) have yielded its position relative to an angularly nearby quasar, its annual proper motion and its trigonometric parallax with formal uncertainties slightly better than 0.2 milli-arcsec. This is the first result of the VLBI astrometric program we are conducting on 11 radio stars similar to sigma-CrB. We plan to obtain comparable results for all stars when enough epochs of observations are acquired. These stars will be used to astrometrically link the Hipparcos and VLBI extragalactic reference frames. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. HAYSTACK OBSERV, WESTFORD, MA 01886 USA. UNIV CALGARY, DEPT PHYS & ASTRON, CALGARY T2N 1N4, ALBERTA, CANADA. RP LESTRADE, JF (reprint author), OBSERV MEUDON, F-92195 MEUDON, FRANCE. NR 17 TC 14 Z9 14 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAY PY 1992 VL 258 IS 1 BP 112 EP 115 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HQ508 UT WOS:A1992HQ50800017 ER PT J AU MARCAIDE, JM ALBERDI, A BARTEL, N CLARK, TA COREY, BE ELOSEGUI, P GORENSTEIN, MV GUIRADO, JC KARDASHEV, N POPOV, M PRESTON, R RATNER, MI RIOJA, MJ ROGERS, AEE SHAPIRO, II AF MARCAIDE, JM ALBERDI, A BARTEL, N CLARK, TA COREY, BE ELOSEGUI, P GORENSTEIN, MV GUIRADO, JC KARDASHEV, N POPOV, M PRESTON, R RATNER, MI RIOJA, MJ ROGERS, AEE SHAPIRO, II TI POSITION AND MORPHOLOGY OF THE COMPACT NONTHERMAL RADIO-SOURCE AT THE GALACTIC-CENTER SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE RADIO SOURCES, SGRA-ASTERISK; GALAXY, CENTER OF; INTERFEROMETRY, VLBI; ASTROMETRY ID SCATTERING; DISK AB We have determined with VLBI the position of the compact nonthermal radio source at the Galactic Center, commonly referred to as SgrA*, in the J2000.0 reference frame of extragalactic radio sources. We have also determined the size of SgrA* at 1.3, 3.6 and 13 cm wavelengths and found that the apparent size of the source increases proportionally to the observing wavelength squared, as expected from source size broadening by interstellar scattering and as reported previously by other authors (e.g. Davies et al. 1976; Marcaide et al. 1985; Lo et al. 1985; Jauncey et al. 1989). We have also established an upper limit of about 8 mJy at 3.6 cm wavelength for any ultracompact component. The actual size of the source is less than 15 AU. Fourier analysis of our very sensitive 3.6 cm observations of this source shows no significant variations of correlated flux density on time scales from 12 to 700 s. C1 MAX PLANCK INST RADIOASTRON, W-5300 BONN 1, GERMANY. HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. HAYSTACK OBSERV, WESTFORD, MA 01886 USA. MOSCOW SPACE RES INST, MOSCOW, USSR. JET PROP LAB, PASADENA, CA 91109 USA. RP MARCAIDE, JM (reprint author), CSIC, INST ASTROFIS ANDALUCIA, APARTADO 3004, E-18080 GRANADA, SPAIN. RI Kardashev, Nikolai/O-6441-2015 NR 24 TC 19 Z9 19 U1 0 U2 1 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 MAY PY 1992 VL 258 IS 2 BP 295 EP 301 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV952 UT WOS:A1992HV95200016 ER PT J AU PAGANI, L WANNIER, PG FRERKING, MA KUIPER, TBH GULKIS, S ZIMMERMANN, P ENCRENAZ, PJ WHITEOAK, JB DESTOMBES, JL PICKETT, HM AF PAGANI, L WANNIER, PG FRERKING, MA KUIPER, TBH GULKIS, S ZIMMERMANN, P ENCRENAZ, PJ WHITEOAK, JB DESTOMBES, JL PICKETT, HM TI SEARCH FOR H2D+ AT 372-GHZ IN DENSE INTERSTELLAR CLOUDS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE INTERSTELLAR MEDIUM, ABUNDANCES; INTERSTELLAR MEDIUM, MOLECULES, H2D+ ID W3 MOLECULAR CLOUD; DETAILED STRUCTURE; LINE; CO; SUBMILLIMETER; KINEMATICS; TRANSITION; COMPLEXES; NGC-7538 AB The 1(10)-1(11) transition of ortho-H2D+ at 372 GHz has been sought in several dark clouds. The transition was not detected; the best upper limits obtained are almost-equal-to 0.3 K (3-sigma). We derive upper limits for the ortho-H2D+ column density and briefly discuss their meaning in comparison with a simple chemical model we have developed (Pagani et al. 1992). C1 JET PROP LAB, PASADENA, CA 91109 USA. UNIV LILLE 1, SPECT HERTZIENNE LAB, F-59655 VILLENEUVE DASCQ, FRANCE. CSIRO, DIV RADIOPHYS, EPPING, NSW 2121, AUSTRALIA. ECOLE NORM SUPER, F-75231 PARIS 05, FRANCE. RP PAGANI, L (reprint author), OBSERV PARIS, SECT MEUDON, DEMIRM, F-92195 MEUDON, FRANCE. NR 30 TC 15 Z9 15 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 MAY PY 1992 VL 258 IS 2 BP 472 EP 478 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV952 UT WOS:A1992HV95200038 ER PT J AU PAGANI, L SALEZ, M WANNIER, PG AF PAGANI, L SALEZ, M WANNIER, PG TI THE CHEMISTRY OF H2D+ IN COLD CLOUDS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE CHEMICAL REACTIONS; INTERSTELLAR MEDIUM, ABUNDANCES; INTERSTELLAR MEDIUM, MOLECULES, H2D+, H-3+ ID DISSOCIATIVE RECOMBINATION; MOLECULAR CLOUDS; H-3+; DEUTERIUM; JUPITER; HCO+; N2H+ AB A simple gas-phase, steady-state chemical model of H2D+ is presented where the ortho/para ratio is investigated in detail. We show that thermal equilibrium should prevail above 20 K but that it is in cold clouds that the ortho form should be the most abundant contrarily to what is expected from thermal equilibrium alone, its abundance being several orders of magnitude larger than previously thought, in which case, cold clouds with high column densities should be the best places to search for this species. We discuss the upper limits derived from our observations (Pagani et al. 1992) in comparison with our model and also reexamine the relations between H2D+ measurements, the DCO+/HCO+ ratio and the abundances of H-3(+), H2D+ and of electrons in dark clouds. Recent findings in observational, theoretical and laboratory astrochemistry make it difficult to derive H-3(+) and e- abundances from these measurements and thus make it difficult to derive the important H2D+/H-3(+) ratio. C1 JET PROP LAB, PASADENA, CA 91109 USA. ECOLE NORM SUPER, F-75231 PARIS 05, FRANCE. RP PAGANI, L (reprint author), OBSERV PARIS, SECT MEUDON, DEMIRM, F-92195 MEUDON, FRANCE. NR 27 TC 60 Z9 60 U1 0 U2 1 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 MAY PY 1992 VL 258 IS 2 BP 479 EP 488 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV952 UT WOS:A1992HV95200039 ER PT J AU NEUGEBAUER, M GOLDSTEIN, BE GOLDSTEIN, R FUSELIER, SA NEUBAUER, FM BALSIGER, H IP, WH AF NEUGEBAUER, M GOLDSTEIN, BE GOLDSTEIN, R FUSELIER, SA NEUBAUER, FM BALSIGER, H IP, WH TI A DIFFERENT VIEW OF PLASMA-FLOW INSIDE P-HALLEY SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COMET P-HALLEY; PLASMA ID GIOTTO; SPECTROMETER AB The Giotto spacecraft carried two different instruments - the JPA and the IMS - for the observation of hot ions in the coma of P/Halley. Although there are many similarities in the time and distance profiles of the plasma flow parameters (bulk velocity, number density, and temperature) computed from the two data sets, there are also some significant differences, especially at cometocentric distances < 5 10(5) km. The principal discrepancies between the JPA results presented by Formisano et al. (1990) and the IMS observations are: (1) the IMS did not detect the levelling off of the speed and temperature profiles that Formisano et al. interpreted as flow stabilization; (2) the IMS detected differential north-south flow between the solar wind and cometary ions for only a brief interval when the magnetic field was oriented nearly southward, whereas Formisano et al. reported more extensive differential north-south flow that was independent of the direction of the field; (3) the JPA ion densities were factors of 2 to 4 higher than the IMS ion densities which, in turn, were an order of magnitude greater than theoretical values. Although some additional source of ionization is required in the theoretical models, we cannot support Formisano et al.'s contention that the critical ionization phenomenon was an important source of ionization in the coma of P/Halley. C1 LOCKHEED PALO ALTO RES LABS, PALO ALTO, CA 94304 USA. UNIV COLOGNE, W-5000 COLOGNE 41, GERMANY. UNIV BERN, CH-3000 BERN, SWITZERLAND. MAX PLANCK INST AERON, W-3411 KATLENBURG DUHM, GERMANY. RP NEUGEBAUER, M (reprint author), JET PROP LAB, MS 169-506, PASADENA, CA 91109 USA. NR 10 TC 9 Z9 9 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 MAY PY 1992 VL 258 IS 2 BP 549 EP 554 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HV952 UT WOS:A1992HV95200046 ER PT J AU WANG, JCL SULKANEN, ME LOVELACE, RVE AF WANG, JCL SULKANEN, ME LOVELACE, RVE TI INTRINSICALLY ASYMMETRIC ASTROPHYSICAL JETS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; GALAXIES, ACTIVE; GALAXIES, JETS; MHD ID COLLIMATED ELECTROMAGNETIC JETS; MAGNETIZED ACCRETION DISKS; ACTIVE GALACTIC NUCLEI; BLACK-HOLES; DYNAMO ACTION; RADIO-SOURCES; VISCOSITY; MODELS; FIELD; QSOS AB This paper extends our previous treatment of the origin of self-collimated electromagnetic jets to the general case where there is no reflection symmetry of the magnetic field about the equatorial plane of the disk. We obtain the axisymmetric field structure inside the disk by solving for the magnetic flux function, PSI(r, z), and the toroidal magnetic field, B(phi)(r, z), from the generalized thin-disk induction equation, which we derive. We obtain the asymptotic (large-z) magnetic field structure outside the disk by solving the force-free Grad-Shafranov equation semianalytically. As in our earlier work, we find jet solutions in which the power flow is carried mainly by the Poynting flux of the electromagnetic field and the angular momentum outflow from the disk is carried by the magnetic field. This power flow is different in general above and below the disk, as discussed briefly in our earlier work. We find that the ratio of the jet luminosities (top/bottom) depends directly on the degree of asymmetry of the field and can easily be much greater than unity. In addition, a significant fraction of the accretion power can be carried by these jets. We argue that the degree of field asymmetry in the disk is determined by the asymmetry of the weak galactic field fed into the disk at large distances over long periods of time. In this way we obtain a statistical relation between the jet asymmetry and the even and odd galactic field components. We discuss these results in light of the observed extragalactic double radio sources. In addition to jet energetics, we study the dynamical effects of asymmetric jets and fields on the black hole-disk system. For typical galactic central stellar densities the displacement of the black hole-disk system caused by asymmetric jets will not be observable. The warping of the disk midplane caused by the asymmetric field structure, on the other hand, may be large. This warping will affect the reprocessing of radiation from different parts of the disk as well as the angular distribution of the escaping radiation. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,XRAY ASTRON BRANCH,HUNTSVILLE,AL 35812. CORNELL UNIV,DEPT APPL PHYS,ITHACA,NY 14853. RP WANG, JCL (reprint author), UNIV TORONTO,CANADIAN INST THEORET ASTROPHYS,60 ST GEORGE ST,TORONTO M5S 1A1,ONTARIO,CANADA. NR 40 TC 38 Z9 39 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 1992 VL 390 IS 1 BP 46 EP 65 DI 10.1086/171258 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HP595 UT WOS:A1992HP59500006 ER PT J AU RAND, RJ KULKARNI, SR RICE, W AF RAND, RJ KULKARNI, SR RICE, W TI STAR FORMATION AND THE DISTRIBUTION OF H-I AND INFRARED-EMISSION IN M51 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ISM; GALAXIES, INDIVIDUAL (M51); INFRARED, GALAXIES; STARS, FORMATION ID GIANT MOLECULAR ASSOCIATIONS; IRAS OBSERVATIONS; SPIRAL STRUCTURE; INTERSTELLAR-MEDIUM; NEARBY GALAXIES; CLOUDS; REGIONS; DUST; ARMS; GAS AB H I, infrared, CO, H-alpha, and B-band observations of M51, the prototypical grand design spiral galaxy, are used to study the consequences of star formation for the distribution of H I and dust. Using the new VLA map of 21 cm emission, our OVRO CO mosaic map, and an H-alpha image, we carry out new tests of the idea of Tilanus & Allen that the H I is largely a photodissociation product in star-forming regions. We confirm that the H I spiral arms are generally coincident with the H II region arms and offset downstream from the CO arms. The radial distributions of total gas, H-alpha, and H I surface density have a simple explanation in the dissociation picture. The distributions also demonstrate how the surface density of H I might be related to the star formation efficiency in molecule-rich galaxies. The large width of the H I regions along the arms compared to that of the giant H II regions can be understood in terms of a simple calculation of the expected size of an H I region associated with a typical giant H II region. The longer lifetime of the stars producing dissociating radiation versus those producing ionizing radiation and the relatively long molecule formation time scale will also contribute to the greater width of the H I arms if stars are continuously forming on the arms. The lack of detailed coincidence of the H I and H II regions along the inner arms has a variety of possible explanations within the dissociation scenario. We carry out two simple tests to probe the origins of the IRAS emission in M51. First, we find that the infrared excess (IRE) of M51 is 24, suggesting that a substantial fraction of the infrared emission arises from dust heated by photons which do not originate in massive star-forming regions. Second, radial cuts through the IRAS maps show that at 12, 25, and 60-mu-m, the arm-interarm contrast of the IRAS emission is substantially less than that of the H-alpha emission (convolved to matching resolutions), providing further evidence for the above explanation and for the existence of a broadly distributed dust component. Deconvolved IRAS maps have improved resolution but do not change this finding. C1 CALTECH, DIV PHYS MATH & ASTRON, PASADENA, CA 91125 USA. CALTECH, CTR INFRARED PROC & ANAL, JET PROPULS LAB, PASADENA, CA 91125 USA. RP UNIV GRONINGEN, KAPTEYN ASTRON INST, POSTBUS 800, 9700 AV GRONINGEN, NETHERLANDS. NR 52 TC 49 Z9 49 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 1992 VL 390 IS 1 BP 66 EP 78 DI 10.1086/171259 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HP595 UT WOS:A1992HP59500007 ER PT J AU STOTHERS, RB CHIN, CW AF STOTHERS, RB CHIN, CW TI STELLAR EVOLUTION IN BLUE POPULOUS CLUSTERS OF THE SMALL MAGELLANIC CLOUD AND THE PROBLEMS OF ENVELOPE SEMICONVECTION AND CONVECTIVE CORE OVERSHOOTING SO ASTROPHYSICAL JOURNAL LA English DT Article DE CONVECTION; MAGELLANIC CLOUDS; OPEN CLUSTERS AND ASSOCIATIONS, INDIVIDUAL (NGC-330, NGC-458; STARS, EVOLUTION ID INTERMEDIATE MASS STARS; H-II REGIONS; EFFECTIVE TEMPERATURES; BOLOMETRIC CORRECTIONS; HEAVY-ELEMENTS; DISTANCE SCALE; NGC 330; SMC; SUPERGIANTS; ABUNDANCES AB Two of the blue populous clusters in the Small Magellanic Cloud, NGC 330 and NGC 458, contain a considerably larger number of evolved stars than are found in comparably young clusters in our Galaxy. This richness makes them valuable tools for studying post-main-sequence evolution in the mass range 4-15 M.. Accordingly, new theoretical evolutionary sequences of models for stars with low metallicities, appropriate to the Small Magellanic Cloud, are derived here with both standard Cox-Stewart opacities and the new Rogers-Iglesias opacities. We find that only those sequences with little or no convective core overshooting can reproduce the two most critical observations: the maximum effective temperature displayed by the hot evolved stars and the difference between the average bolometric magnitudes of the hot and cool evolved stars. An upper limit to the ratio of the mean overshoot distance beyond the classical Schwarzschild core boundary to the local pressure scale height can be set at d/H(P) < 0.2. Although the use of the maximum effective temperature is subject to certain mild restrictions, the bolometric magnitude difference is an ideal quantity, being sensitive only to the stellar core mass. A second important result derived here from the frequency of cool supergiants in NGC 330 is that the Ledoux criterion (rather than the Schwarzschild criterion) for convection and semiconvection in the envelopes of massive stars is strongly favored. Both conclusions are independent of current uncertainties about the adopted stellar metallicities and the radiative opacities. However, the Rogers-Iglesias opacities produce superior model fits to other observational quantities. Residuals from the fitting for NGC 330 suggest the possibility of fast interior rotation in the stars of this cluster. NGC 330 and NGC 458 turn out to have ages of approximately 3 x 10(7) yr and approximately 1 x 10(8) yr, respectively. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 71 TC 79 Z9 79 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 1992 VL 390 IS 1 BP 136 EP 143 DI 10.1086/171266 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HP595 UT WOS:A1992HP59500014 ER PT J AU TEREBEY, S VOGEL, SN MYERS, PC AF TEREBEY, S VOGEL, SN MYERS, PC TI PROBING THE CIRCUMSTELLAR ENVIRONMENTS OF VERY YOUNG LOW-MASS STARS USING WATER MASERS SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; MASERS; RADIO CONTINUUM, STARS; STARS, FORMATION; STARS, MASS LOSS ID DENSE CORES; IRAS SOURCES; DARK CLOUDS; H2O MASERS; MOLECULAR CLOUD; BIPOLAR OUTFLOW; RESOLUTION; PROTOSTARS; EVOLUTION; L1551 AB We have used the VLA to search nearby very young low-mass stars for water maser emission. The sample consists of 26 low-luminosity IRAS sources embedded in dense molecular cores, a class of sources suspected to be newly forming low-mass stars on the order of a few hundred thousand years old. Three sources were detected: IRAS 16293 - 2422 in L1689, 05417 + 0907 in B35, and 16244 - 2432 in L1681B. The maser detection rate of 10% for the IRAS-dense cores is comparable to rates found in surveys of similar but typically higher luminosity sources. High spatial resolution maps show the region of maser emission is generally confined to an area smaller than approximately 0.5" (approximately 100 AU) near the star, and the velocities of individual components span intervals ranging from 20 to 40 km s-1. The maser velocities are too large to be due to gravitational motions in at least two of the sources, implying that the masers are associated with the winds from the young low-mass stars. Using the positions of the masers as probes of the wind's spatial structure provides a way to trace the collimation of the wind very close to the young star. Comparing the high spatial resolution maser data to lower resolution CO data shows no evidence for higher collimation close to the star-the stellar wind cavity appears to have similar collimation at 10(15) cm as at 10(17)-10(18) cm. C1 CALTECH,CTR INFRARED PROC & ANAL 10022,JET PROPULS LAB,PASADENA,CA 91125. UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP TEREBEY, S (reprint author), CALTECH,CANADIAN INST THEORET ASTROPHYS,PASADENA,CA 91125, USA. NR 47 TC 36 Z9 36 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 1992 VL 390 IS 1 BP 181 EP 190 DI 10.1086/171269 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HP595 UT WOS:A1992HP59500017 ER PT J AU STOTHERS, RB CHIN, CW AF STOTHERS, RB CHIN, CW TI CRITERION FOR CONVECTION IN AN INHOMOGENEOUS STAR SO ASTROPHYSICAL JOURNAL LA English DT Article DE CONVECTION; STARS, INTERIORS ID LARGE MAGELLANIC CLOUD; SUPERGIANTS; ABUNDANCES; EVOLUTION; DIAGRAM AB To resolve the question of whether the Schwarzschild criterion or the Ledoux criterion should be used to test for convective instability in a star, a well-observed cluster of chemically inhomogeneous massive stars, in which the choice of the criterion for convection makes a crucial and easily observable difference, is required. NGC 330, a metal-poor cluster in the Small Magellanic Cloud, is ideal for this test. Its large evolved stellar population contains both blue and red supergiants, of which its many red supergiants should be absent if a gradient of mean molecular weight did not choke off rapid convective motions in the inhomogeneous region connecting the envelope and core. Thus the Ledoux criterion for convection is strongly indicated as being correct. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,GREENBELT,MD 20771, USA. NR 37 TC 19 Z9 19 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAY 1 PY 1992 VL 390 IS 1 BP L33 EP L35 DI 10.1086/186365 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HP596 UT WOS:A1992HP59600009 ER PT J AU PRESTWICH, AH WRIGHT, GS JOSEPH, RD AF PRESTWICH, AH WRIGHT, GS JOSEPH, RD TI VARIABILITY OF NEAR-INFRARED EMISSION-LINES IN NGC-4151 - IMPLICATIONS FOR NUCLEAR STAR FORMATION SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE GALAXIES; ACTIVE; GALAXIES; INDIVIDUAL (NGC-4151); GALAXIES; NUCLEI; GALAXIES; SEYFERT; GALAXIES; STELLAR CONTENT ID SEYFERT AB Multi-aperture infrared spectra of the circumnuclear region of the Seyfert galaxy NGC 4151 taken over a 10 year period show that the N = 7-4 B-gamma-hydrogen recombination line is variable. The H2 quadrupole line emission shows no sign of variability. We show that there is a substantial contribution to the nuclear B-gamma flux from the active nucleus, making it impossible to determine star formation rates from infrared hydrogen recombination lines in active galaxies. The lack of variability in the H2 line fluxes indicates that ionizing photons from the active nucleus is not important in exciting the molecular line emission. C1 JOINT ASTRON CTR,HILO,HI 96720. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP PRESTWICH, AH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES65,HUNTSVILLE,AL 35812, USA. NR 6 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAY PY 1992 VL 80 IS 1 BP 205 EP 209 DI 10.1086/191663 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HR035 UT WOS:A1992HR03500004 ER PT J AU CARGILL, KL PYLE, BH SAUER, RL MCFETERS, GA AF CARGILL, KL PYLE, BH SAUER, RL MCFETERS, GA TI EFFECTS OF CULTURE CONDITIONS AND BIOFILM FORMATION ON THE IODINE SUSCEPTIBILITY OF LEGIONELLA-PNEUMOPHILA SO CANADIAN JOURNAL OF MICROBIOLOGY LA English DT Article DE LEGIONELLA-PNEUMOPHILA; IODINE; DISINFECTION; GROWTH CONDITIONS; BIOFILMS; WATER ID WATER DISTRIBUTION-SYSTEMS; COMPARATIVE RESISTANCE; LEGIONNAIRES DISEASE; CHLORINE RESISTANCE; TAP WATER; BACTERIA; SURVIVAL; DISINFECTANTS; INACTIVATION; SENSITIVITY AB The susceptibility of Legionella pneumophila to iodination was studied with cultures grown in well water, on rich agar media, and attached to stainless-steel surfaces. Legionella pneumophila grown in water cultures in association with other microorganisms were less sensitive to disinfection by chlorine and iodine than were agar-passaged cultures. Differences in sensitivity to disinfection between water-cultured and agar-grown legionellae were determined by comparing C x T values (concentration in milligrams per litre multiplied by time in minutes to achieve 99% decrease in viability) and C(M) x T values (concentration in molarity). Iodine (1500 x ) gave a greater difference in C(M) x T values than did chlorine (68 x ). Iodine was 50 times more effective than chlorine when used with agar-grown cultures but was only twice as effective when tested against water-grown Legionella cultures. C x T x S values (C x T multiplied by percent survivors), which take into consideration the percent surviving bacteria, were used to compare sensitivities in very resistant populations, such as those in biofilms. Water cultures of legionellae associated with stainless-steel surfaces were 135 times more resistant to iodination than were unattached legionellae, and they were 210 000 times more resistant than were agar-grown cultures. These results indicate that the conditions under which legionellae are grown can dramatically affect their susceptibility to some disinfectants and must be considered when evaluating the efficacy of a disinfecting agent. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP MCFETERS, GA (reprint author), MONTANA STATE UNIV,DEPT MICROBIOL,BOZEMAN,MT 59717, USA. NR 38 TC 64 Z9 66 U1 0 U2 1 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4166 J9 CAN J MICROBIOL JI Can. J. Microbiol. PD MAY PY 1992 VL 38 IS 5 BP 423 EP 429 PG 7 WC Biochemistry & Molecular Biology; Biotechnology & Applied Microbiology; Immunology; Microbiology SC Biochemistry & Molecular Biology; Biotechnology & Applied Microbiology; Immunology; Microbiology GA JD669 UT WOS:A1992JD66900011 PM 1643585 ER PT J AU SODUPE, M BAUSCHLICHER, CW PARTRIDGE, H AF SODUPE, M BAUSCHLICHER, CW PARTRIDGE, H TI A THEORETICAL-STUDY OF MG(CO2)N+ AND SR(CO2)N+ FOR N=1 AND 2 AND MG2CO2+ SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; ROW ATOMS; CONTRACTION; ORBITALS; ENERGY AB The structure and binding energies are determined for Mg(CO2)n+ and Sr(CO2)n+ for n = 1 and 2. We also consider Mg2+ and Mg2CO2+ to compare the binding of CO2 to a single metal ion with the binding to a diatomic ion. The vertical excitation energies are computed for all species. The potential energy curves for the low-lying states of Mg2+ are reported. The MgCO2+ results are in good agreement with the experimental results of Duncan and co-workers. RP SODUPE, M (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Sodupe, Mariona/E-9352-2013 OI Sodupe, Mariona/0000-0003-0276-0524 NR 20 TC 73 Z9 73 U1 0 U2 9 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 MAY 1 PY 1992 VL 192 IS 2-3 BP 185 EP 194 DI 10.1016/0009-2614(92)85450-O PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA HT122 UT WOS:A1992HT12200008 ER PT J AU STEINBERG, TA MULHOLLAND, GP WILSON, DB BENZ, FJ AF STEINBERG, TA MULHOLLAND, GP WILSON, DB BENZ, FJ TI THE COMBUSTION OF IRON IN HIGH-PRESSURE OXYGEN SO COMBUSTION AND FLAME LA English DT Article ID FIRE SPREAD AB The combustion of 0.32-cm-diameter pure iron rods at 6.9 MPa oxygen pressure was investigated. During the upward burning of the sample rods, it was found that there was excess oxygen above the stoichiometric requirement for the formation of the product oxide in the formed molten ball. The excess oxygen in the formed molten ball suggests that the rate limiting step for iron combustion, at 6.9 MPa, is the kinetic reaction at a molten iron core in the ball, and not oxygen intake into the molten ball as previously thought. Glassman's hypothesis as to the phase in which a metal bums was investigated and found to be inappropriate for iron for the pressure considered. C1 NEW MEXICO STATE UNIV,LAS CRUCES,NM 88003. NASA,WHITE SANDS TEST FACIL,LAS CRUCES,NM. RP STEINBERG, TA (reprint author), LOCKHEED ESC,WHITE SANDS TEST FACIL,LAS CRUCES,NM, USA. OI Steinberg, Theodore/0000-0002-9270-4130 NR 20 TC 14 Z9 14 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD MAY PY 1992 VL 89 IS 2 BP 221 EP 228 DI 10.1016/0010-2180(92)90030-S PG 8 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA HT854 UT WOS:A1992HT85400008 ER PT J AU SCHWENKE, DW AF SCHWENKE, DW TI ON THE COMPUTATION OF RO-VIBRATIONAL ENERGY-LEVELS OF TRIATOMIC-MOLECULES SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article ID WATER MOLECULE; QUADRATURE; EQUATIONS AB We describe a new code for computing ro-vibrational energy levels for general triatomic molecules. The numerical implementation is discussed in detail and sample results are given for the water molecule. The method is capable of very high accuracy with little difficulty. RP SCHWENKE, DW (reprint author), NASA, AMES RES CTR, MS 230-3, MOFFETT FIELD, CA 94035 USA. RI schwenke, david/I-3564-2013 NR 18 TC 38 Z9 38 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD MAY PY 1992 VL 70 IS 1 BP 1 EP 14 DI 10.1016/0010-4655(92)90086-E PG 14 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA HT370 UT WOS:A1992HT37000001 ER PT J AU DAGUM, L AF DAGUM, L TI DATA PARALLEL SORTING FOR PARTICLE SIMULATION SO CONCURRENCY-PRACTICE AND EXPERIENCE LA English DT Article ID ALGORITHMS AB Sorting on a parallel architecture is a communications intensive event which can incur a high penalty in applications where it is required. In the case of particle simulation, only integer sorting is necessary, and sequential implementations easily attain the minimum performance bound or O(N) for N particles. Parallel implementations, however, have to cope with the parallel sorting problem which, in addition to incurring a heavy communications cost, can make the minimum performance bound difficult to attain. This paper demonstrates how the sorting problem in a particle simulation can be reduced to a merging problem, and describes an efficient data parallel algorithm to solve this merging problem in a particle simulation. The new algorithm is shown to be optimal under conditions usual for particle simulation, and its fieldwise implementation on the Connection Machine is analysed in detail. The new algorithm is about four times faster than a fieldwise implementation of radix sort on the Connection Machine. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 13 TC 2 Z9 2 U1 0 U2 2 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 1040-3108 J9 CONCURRENCY-PRACT EX JI Concurrency-Pract. Exp. PD MAY PY 1992 VL 4 IS 3 BP 241 EP 255 DI 10.1002/cpe.4330040304 PG 15 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA HV204 UT WOS:A1992HV20400003 ER PT J AU KRISHNAN, R SOMMER, HJ SPIDALIERE, PD AF KRISHNAN, R SOMMER, HJ SPIDALIERE, PD TI MONOCULAR POSE OF A RIGID BODY USING POINT LANDMARKS SO CVGIP-IMAGE UNDERSTANDING LA English DT Article ID CALIBRATION C1 NASA,GODDARD SPACE FLIGHT CTR,FLIGHT TELEROBOT SERV,GREENBELT,MD 20771. RP KRISHNAN, R (reprint author), PENN STATE UNIV,DEPT MECH ENGN,UNIV PK,PA 16802, USA. NR 23 TC 4 Z9 4 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 1049-9660 J9 CVGIP-IMAG UNDERSTAN PD MAY PY 1992 VL 55 IS 3 BP 307 EP 316 DI 10.1016/1049-9660(92)90028-2 PG 10 WC Computer Science, Software Engineering SC Computer Science GA HR064 UT WOS:A1992HR06400007 ER PT J AU PHINNEY, WC AF PHINNEY, WC TI PARTITION-COEFFICIENTS FOR IRON BETWEEN PLAGIOCLASE AND BASALT AS A FUNCTION OF OXYGEN FUGACITY - IMPLICATIONS FOR ARCHEAN AND LUNAR ANORTHOSITES SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID ORIGIN AB Experimental studies were undertaken to determine D for FeOT between plagioclase and melt as a function of oxygen fugacity for a basaltic composition that occurs as matrices for plagioclase megacrysts that are similar to those in calcic anorthosites. At liquidus conditions, the D for FeOT between calcic plagioclase and tholeiitic basalt changes very little, from 0.030 to 0.044, between the very low f(O2) of the iron-wustite buffer and that of the quartz-fayalite-magnetite (QFM) buffer. At fugacities above QFM the value for D increases rapidly to 0.14 at the magnetite-hematite buffer and 0.36 in air. The increase in D results from the fact that nearly all of the Fe is in the Fe2+ state at f(O2) below QFM, and the Fe3+/Fe2+ ratio in the melt increases rapidly above QFM causing more Fe to enter the plagioclase which accepts Fe3+ more readily than Fe2+. There is essentially no change in values of D over cooling rates that vary by two orders of magnitude. The D for FeOT of 0.030 at iron-wustite is in good agreement with earlier studies at low f(O2). Terrestrial calcic plagioclase-matrix pairs display Ds of about 0.043, in excellent agreement with the experimental value of 0.044 at QFM which is the accepted fugacity for terrestrial tholeiitic basalts. Application of the Ds for FeOT and other components to terrestrial calcic anorthosites indicates that the anorthosites were in equilibrium with nearby coeval tholeiitic basalts at QFM, as was expected. Lunar anorthosites, however, have anomalously low contents of FeOT as well as MgO and would be in equilibrium with melts that are several times lower in these components than expected. The low values of FeOT and MgO in the plagioclase of lunar anorthosites are a result of subsolidus reequilibration with pyroxene, olivine, and other Fe-Mg-bearing phases during high-temperature metamorphism, as is the case in terrestrial anorthosites that have undergone granulite-grade metamorphism. The Ds for K2O, MgO, and TiO2 were determined as 0.21, 0.044, and 0.033, respectively, and show no variation with f(O2). The value for K2O is in good agreement with natural assemblages. The values for MgO and TiO2, however, are lower in natural assemblages; but the high degree of mobility of Mg and the very low contents of TiO2 in plagioclase makes the reliability of the natural values rather low. Also, the D for TiO2 may be affected by rate of cooling. Attempts to determine the D for Cr2O3 as a function of f(O2) were made difficult by the low levels of Cr2O3 (300 to 500 ppm) in the melt when saturation with a Cr spinel occurred. Because the Cr concentrations in plagioclase are nearly 100 times less than those in the melt, it was not possible to obtain reliable analyses for plagioclase. These uncertainties constrain the D for Cr to be less than 0.07 at the QFM buffer. RP PHINNEY, WC (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 24 TC 43 Z9 43 U1 1 U2 8 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD MAY PY 1992 VL 56 IS 5 BP 1885 EP 1895 DI 10.1016/0016-7037(92)90318-D PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA HU413 UT WOS:A1992HU41300009 ER PT J AU CHANDLER, MA RIND, D RUEDY, R AF CHANDLER, MA RIND, D RUEDY, R TI PANGAEAN CLIMATE DURING THE EARLY JURASSIC - GCM SIMULATIONS AND THE SEDIMENTARY RECORD OF PALEOCLIMATE SO GEOLOGICAL SOCIETY OF AMERICA BULLETIN LA English DT Article ID SURFACE-TEMPERATURE-GRADIENT; WESTERN UNITED-STATES; CRETACEOUS CLIMATE; EOLIAN SANDSTONES; RADIATION BUDGET; GEOLOGIC RECORD; SEASONAL CYCLE; ICE-AGE; CIRCULATION; MODEL AB Results from new simulations of the Early Jurassic climate show that increased ocean heat transport may have been the primary force generating warmer climates during the past 180 m.y. The simulations, conducted using the general circulation model (GCM) at the Goddard Institute for Space Studies, include realistic representations of paleocontinental distribution, topography, epeiric seas, and vegetation, in order to facilitate comparisons between model results and paleoclimate data. Three major features of the simulated Early Jurassic climate include the following. (1) A global warming, compared to the present, of 5-degrees-C to 10-degrees-C, with temperature increases at high latitudes five times this global average. Average summer temperatures exceed 35-degrees-C in low-latitude regions of western Pangaea where eolian sandstones testify to the presence of vast deserts. (2) Simulated precipitation and evaporation patterns agree closely with the moisture distribution interpreted from evaporites, and coal deposits. High rainfall rates are associated primarily with monsoons that originate over the warm Tethys Ocean. Unlike the "megamonsoons" proposed in previous studies, these systems are found to be associated with localized pressure cells whose positions are controlled by topography and coastal geography. (3) Decreases in planetary albedo, occurring because of reductions in sea ice, snow cover, and low clouds, and increases in atmospheric water vapor are the positive climate feedbacks that amplify the global warming. Similar to other Mesozoic climate simulations, our model finds that large seasonal temperature fluctuations occurred over mid- and high-latitude continental interiors, refuting paleoclimate evidence that suggests more equable conditions. Sensitivity experiments suggest that some combination of ocean heat transport increase, high levels of CO2, and improved modeling of ground hydrological schemes may lead to a better match with the geologic record. We speculate, also, that the record itself is biased toward "equable" climatic conditions, a suggestion that may be tested by comparing GCM results with more detailed phytogeographic analyses. C1 COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,DEPT GEOL SCI,PALISADES,NY 10964. RP CHANDLER, MA (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 100 TC 109 Z9 113 U1 4 U2 15 PU GEOLOGICAL SOC AMERICA PI BOULDER PA PO BOX 9140 3300 PENROSE PLACE, BOULDER, CO 80301 SN 0016-7606 J9 GEOL SOC AM BULL JI Geol. Soc. Am. Bull. PD MAY PY 1992 VL 104 IS 5 BP 543 EP 559 DI 10.1130/0016-7606(1992)104<0543:PCDTEJ>2.3.CO;2 PG 17 WC Geosciences, Multidisciplinary SC Geology GA HT490 UT WOS:A1992HT49000004 ER PT J AU LANGEL, RA AF LANGEL, RA TI INTERNATIONAL REFERENCE GEOMAGNETIC-FIELD UPDATED IN 1991 SO GEOMAGNETIZM I AERONOMIYA LA Russian DT Editorial Material ID GENERATION RP LANGEL, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU MEZHDUNARODNAYA KNIGA PI MOSCOW PA 39 DIMITROVA UL., 113095 MOSCOW, RUSSIA SN 0016-7940 J9 GEOMAGN AERON+ JI Geomagn. Aeron. PD MAY-JUN PY 1992 VL 32 IS 3 BP 183 EP 188 PG 6 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA JQ480 UT WOS:A1992JQ48000034 ER PT J AU CHASSEFIERE, E BLAMONT, JE KRASNOPOLSKY, VA KORABLEV, OI ATREYA, SK WEST, RA AF CHASSEFIERE, E BLAMONT, JE KRASNOPOLSKY, VA KORABLEV, OI ATREYA, SK WEST, RA TI VERTICAL STRUCTURE AND SIZE DISTRIBUTIONS OF MARTIAN AEROSOLS FROM SOLAR OCCULTATION MEASUREMENTS SO ICARUS LA English DT Article ID WATER-VAPOR; ATMOSPHERE; MARS; STABILITY; CIRCULATION; DUST C1 MOSCOW SPACE RES INST,117810 MOSCOW,USSR. UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. RP CHASSEFIERE, E (reprint author), CNRS,SERV AERON,BP 3,F-91371 VERRIERES BUISSON,FRANCE. RI Korablev, Oleg/L-5083-2013; Krasnopolsky, Vladimir/L-5085-2013; OI Korablev, Oleg/0000-0003-1115-0656 NR 40 TC 62 Z9 63 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1992 VL 97 IS 1 BP 46 EP 69 DI 10.1016/0019-1035(92)90056-D PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY536 UT WOS:A1992HY53600004 ER PT J AU JACKSON, AA ZOOK, HA AF JACKSON, AA ZOOK, HA TI ORBITAL EVOLUTION OF DUST PARTICLES FROM COMETS AND ASTEROIDS SO ICARUS LA English DT Article ID INTERPLANETARY DUST; SOLAR-SYSTEM; ZODIACAL DUST; IRAS; DYNAMICS; ORIGIN; BANDS C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP JACKSON, AA (reprint author), LOCKHEED ENGN & SCI CO,HOUSTON,TX 77258, USA. NR 31 TC 69 Z9 69 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1992 VL 97 IS 1 BP 70 EP 84 DI 10.1016/0019-1035(92)90057-E PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY536 UT WOS:A1992HY53600005 ER PT J AU MAGNUSSON, P BARUCCI, MA BINZEL, RP BLANCO, C DIMARTINO, M GOLDADER, JD GONANOBEURER, M HARRIS, AW MICHALOWSKI, T MOTTOLA, S THOLEN, DJ WISNIEWSKI, WZ AF MAGNUSSON, P BARUCCI, MA BINZEL, RP BLANCO, C DIMARTINO, M GOLDADER, JD GONANOBEURER, M HARRIS, AW MICHALOWSKI, T MOTTOLA, S THOLEN, DJ WISNIEWSKI, WZ TI ASTEROID 951-GASPRA - PRE-GALILEO PHYSICAL MODEL SO ICARUS LA English DT Article ID LIGHTCURVES; POLE C1 OBSERV PARIS,F-92195 MEUDON,FRANCE. MIT,CAMBRIDGE,MA 02139. UNIV CATANIA,IST ASTRON,I-95125 CATANIA,ITALY. OSSERV ASTRON TORINO,I-10025 PINO TORINESE,ITALY. INST ASTRON,HONOLULU,HI 96822. DEUTSCH FORSCHUNGSANSTALT LUFT & RAUMFAHRT,GERMAN AEROSP RES ESTAB,W-8031 OBERPFAFFENHOFEN,GERMANY. JET PROP LAB,PASADENA,CA 91109. ADAM MICKIEWICZ UNIV,ASTRON OBSERV,PL-60286 POZNAN,POLAND. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RP MAGNUSSON, P (reprint author), QUEEN MARY & WESTFIELD COLL,SCH MATH SCI,LONDON E1 4NS,ENGLAND. NR 28 TC 18 Z9 18 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1992 VL 97 IS 1 BP 124 EP 129 DI 10.1016/0019-1035(92)90061-B PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY536 UT WOS:A1992HY53600009 ER PT J AU MUELLER, BEA THOLEN, DJ HARTMANN, WK CRUIKSHANK, DP AF MUELLER, BEA THOLEN, DJ HARTMANN, WK CRUIKSHANK, DP TI EXTRAORDINARY COLORS OF ASTEROIDAL OBJECT (5145) 1992-AD SO ICARUS LA English DT Note ID COLORIMETRY C1 UNIV HAWAII,HONOLULU,HI 96822. PLANETARY SCI INST,TUCSON,AZ 85704. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP MUELLER, BEA (reprint author), KITT PEAK NATL OBSERV,TUCSON,AZ 85719, USA. NR 30 TC 58 Z9 58 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1992 VL 97 IS 1 BP 150 EP 154 DI 10.1016/0019-1035(92)90065-F PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY536 UT WOS:A1992HY53600013 ER PT J AU DISANTI, MA MUMMA, MJ LACY, JH AF DISANTI, MA MUMMA, MJ LACY, JH TI A SENSITIVE UPPER LIMIT TO OCS IN COMET AUSTIN (1989C1) FROM A SEARCH FOR NU-3 EMISSION AT 4.85 MU-M SO ICARUS LA English DT Note RP DISANTI, MA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,EXTRATERR PHYS,GREENBELT,MD 20771, USA. RI mumma, michael/I-2764-2013 NR 21 TC 8 Z9 8 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAY PY 1992 VL 97 IS 1 BP 155 EP 158 DI 10.1016/0019-1035(92)90066-G PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HY536 UT WOS:A1992HY53600014 ER PT J AU CHOU, JJ PIEGL, LA AF CHOU, JJ PIEGL, LA TI DATA REDUCTION USING CUBIC RATIONAL B-SPLINES SO IEEE COMPUTER GRAPHICS AND APPLICATIONS LA English DT Article ID CURVE AB This algorithm fits rational cubic B-spline curves to 2D or 3D data points to create a piecewise cubic curve that fits the data accurately. C1 UNIV S FLORIDA,DEPT COMP SCI & ENGN,4202 E FOWLER AVE,ENG 118,TAMPA,FL 33620. NASA,AMES RES CTR,COMP SCI CORP,MOFFETT FIELD,CA 94035. NR 11 TC 10 Z9 10 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0272-1716 J9 IEEE COMPUT GRAPH JI IEEE Comput. Graph. Appl. PD MAY PY 1992 VL 12 IS 3 BP 60 EP 68 DI 10.1109/38.135914 PG 9 WC Computer Science, Software Engineering SC Computer Science GA HT917 UT WOS:A1992HT91700009 ER PT J AU CHEUNG, KM AF CHEUNG, KM TI ON THE DECODER ERROR-PROBABILITY OF BLOCK-CODES SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Letter ID REED-SOLOMON CODES AB By using coding and combinational techniques, an explicit formula is derived which enumerates the complete weight distribution of decodable words of block codes using partially known weight distributions. Also an approximation formula for nonbinary block codes is obtained. These results in turn give exact and approximate expressions for the decoder error probability [P(E)(u) of block codes. RP CHEUNG, KM (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD MAY PY 1992 VL 40 IS 5 BP 857 EP 859 DI 10.1109/26.141450 PG 3 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA HY364 UT WOS:A1992HY36400001 ER PT J AU FAN, MS CHRISTOU, A PECHT, MG AF FAN, MS CHRISTOU, A PECHT, MG TI 2-DIMENSIONAL THERMAL MODELING OF POWER MONOLITHIC MICROWAVE INTEGRATED-CIRCUITS (MMICS) SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article AB Numerical simulations of the two-dimensional temperature distributions for a typical GaAs MMIC circuit are conducted, aiming at understanding the heat conduction process of the circuit chip and providing temperature information for device reliability analysis. The method used is to solve the two-dimensinal heat conduction equation with a control-volume-based finite difference scheme. In particular, the effects of the power dissipation and the ambient temperature are examined, and the criterion for the worst operating environment is discussed in terms of the allowed highest device junction temperature. C1 UNIV MARYLAND,COMP AIDED LIFE CYCLE ENGN,ELECTR PACKAGING RES CTR,COLLEGE PK,MD 20742. RP FAN, MS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNISYS,ELECTR PACKAGING & ASSEMBLY PROGRAM,GREENBELT,MD 20771, USA. NR 6 TC 8 Z9 9 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD MAY PY 1992 VL 39 IS 5 BP 1075 EP 1079 DI 10.1109/16.129085 PG 5 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA HP269 UT WOS:A1992HP26900009 ER PT J AU ROBINSON, WD KUMMEROW, C OLSON, WS AF ROBINSON, WD KUMMEROW, C OLSON, WS TI A TECHNIQUE FOR ENHANCING AND MATCHING THE RESOLUTION OF MICROWAVE MEASUREMENTS FROM THE SSM/I INSTRUMENT SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. UNIV WISCONSIN,COOPERAT INST METEOROL SATELLITE STUDIES,MADISON,WI 53706. NR 5 TC 52 Z9 57 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1992 VL 30 IS 3 BP 419 EP 429 DI 10.1109/36.142920 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 JA318 UT WOS:A1992JA31800001 ER PT J AU BERENDES, T SENGUPTA, SK WELCH, RM WIELICKI, BA NAVAR, M AF BERENDES, T SENGUPTA, SK WELCH, RM WIELICKI, BA NAVAR, M TI CUMULUS CLOUD-BASE HEIGHT ESTIMATION FROM HIGH SPATIAL-RESOLUTION LANDSAT DATA - A HOUGH TRANSFORM APPROACH SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID SATELLITE DATA; SURFACE AB Cloud base height is an essential variable governing surface energy budgets, but it is notoriously difficult to determine using satellite data. This study develops a semiautomated methodology to estimate cumulus cloud base heights using high spatial resolution LANDSAT Multispectral Scanner data. The approach employs a variety of image processing techniques to match cloud edges with their corresponding shadow edges. Cloud base height then is estimated by computing the separation distance between the corresponding Generalized Hough Transform reference points. Sixteen subregions, each 30 km x 30 km in size, are selected for four LANDSAT scenes. Standard deviations of cloud base height within each of the subregions range from about 100 m to 150 m. Differences between cloud base heights computed using the Hough Transform and a manual verification technique are small (on the order of 100 m or less). The cloud base heights also compare favorably with the few surface observations available. On the basis of these results, it is estimated that cloud base height accuracies of 50-70 m may be possible using HIRIS and ASTER instruments in the EOS Global Climate Change program. C1 LAWRENCE LIVERMORE NATL LAB,LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94551. USN,OCEANOG & ATMOSPHER RES LAB,MONTEREY,CA 93943. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP BERENDES, T (reprint author), S DAKOTA SCH MINES & TECHNOL,INST ATMOSPHER SCI,RAPID CITY,SD 57701, USA. NR 24 TC 19 Z9 19 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1992 VL 30 IS 3 BP 430 EP 443 DI 10.1109/36.142921 PG 14 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA JA318 UT WOS:A1992JA31800002 ER PT J AU WALTER, SJ BENDER, PL AF WALTER, SJ BENDER, PL TI THE SLANT PATH ATMOSPHERIC REFRACTION CALIBRATOR - AN INSTRUMENT TO MEASURE THE MICROWAVE PROPAGATION DELAYS INDUCED BY ATMOSPHERIC WATER-VAPOR SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB The Slant Path Atmospheric Refraction Calibrator, SPARC, has been developed to measure the water vapor induced propagation delay experienced by a radio signal traversing the atmosphere. SPARC measures the difference in the travel times between an optical and a microwave signal propagating along the same atmospheric path. Since the refractivity of dry air is similar for both the microwave and optical signals, the difference in arrival times is a sensitive measure of the water vapor induced microwave delay. The instrument is capable of measuring the difference in the optical and microwave travel times with an accuracy of 15 ps or better. SPARC was developed to provide an accurate, independent method for evaluating other techniques used to determine the atmospheric water vapor induced delay. The theoretical and experimental issues involved in making measurements of the delay induced by water vapor will be discussed. Measurements along a 13.35-km ground-based path will be presented which will illustrate the instrument's stability, precision, and accuracy. C1 NATL INST STAND & TECHNOL,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. UNIV COLORADO,BOULDER,CO 80309. NATL INST STAND & TECHNOL,DIV QUANTUM PHYS,BOULDER,CO. RP WALTER, SJ (reprint author), JET PROP LAB,MICROWAVE OBSERVAT SYST SECT,PASADENA,CA 91109, USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1992 VL 30 IS 3 BP 462 EP 471 DI 10.1109/36.142924 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 JA318 UT WOS:A1992JA31800005 ER PT J AU KIM, YJ RODRIGUEZ, E AF KIM, YJ RODRIGUEZ, E TI COMPARISON OF THE UNIFIED PERTURBATION METHOD WITH THE 2-SCALE EXPANSION SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID SCATTERING; SURFACES; APPROXIMATION; WAVES AB In previous papers, we presented the Unified Perturbation Method (UPM), which converges faster over a wider domain of surface roughness than other perturbations, such as the small perturbation method (SPM), the phase perturbation method, the Kirchhoff approximation, and the momentum transfer expansion (MTE). It can be shown that UPM intrinsically possesses characteristics similar to the two-scale expansion without requiring a free parameter. In this paper, we consider whether the UPM can be improved by applying the two-scale concept to the method. In order to do so, we expand the unknown source current in a two-scale manner starting from the extinction theorem. Several two-scale expansions are derived and are compared with the conventional two-scale approximation. It is shown that the UPM performs best without two-scale expansions. In addition, we also present the optimum spectral split of the various two-scale theories considered here. RP KIM, YJ (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 16 TC 8 Z9 8 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1992 VL 30 IS 3 BP 510 EP 515 DI 10.1109/36.142929 PG 6 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA JA318 UT WOS:A1992JA31800010 ER PT J AU FREEMAN, A VANZYL, JJ KLEIN, JD ZEBKER, HA SHEN, Y AF FREEMAN, A VANZYL, JJ KLEIN, JD ZEBKER, HA SHEN, Y TI CALIBRATION OF STOKES AND SCATTERING MATRIX FORMAT POLARIMETRIC SAR DATA SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID PHASE CALIBRATION; RADAR IMAGES AB Several different approaches to calibration of polarimetric radar image data have appeared recently in the literature. In particular, several papers by JPL authors have offered different perspectives on the polarimetric radar calibration problem. In this paper, we compare two of these approaches and demonstrate their functional equivalence. We show how one of the algorithms can be adapted to calibrate both scattering matrix and Stokes matrix format polarimetric radar data. Klein [1] has presented an approach for calibrating polarimetric SAR data in scattering matrix format, which relies on backscatter reciprocity and the lack of correlation between like- and cross-pol backscatter found in many natural targets. van Zyl [21 has presented an approach to the calibration of Stokes matrix (compressed) format polarimetric radar data, which is based on the assumption of reciprocity between the radar receive (R) and transmit (T) matrix representations. Both these approaches require one or more trihedral corner reflectors within the imaged scene. Freeman et al. [3] have presented an approach based on using three polarimetric active radar calibrators (PARC's) within the imaged scene. In general, techniques such as that described in [31, using three known (man-made) targets located at a single point will not be successful in calibrating all types of polarimetric radar data, because of the possibility of large variations in cross-talk amplitude and phase across the image swath. In this paper, we show that the assumptions about the backscatter and the polarimetric radar system for the two approaches described in Klein's and van Zyl's papers are equivalent. We demonstrate that, to first order in the radar system cross talk (i.e., neglecting terms of second order and above) an exact solution to the Stokes matrix format data calibration problem exists. We call this the first-order solution, for convenience. Next, we show that van Zyl's approach can give this first-order solution for appropriately symmetrized polarimetric radar data. Then we show how, if the data is properly symmetrized, van Zyl's approach can be used to calibrate both scattering matrix and Stokes matrix format data. These conclusions should be generally applicable to polarimetric imaging radar system data. The method is illustrated on NASA/JPL DC-8 SAR data and the results of calibrating in either scattering matrix or Stokes matrix format are shown to be in excellent agreement. RP FREEMAN, A (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 15 TC 35 Z9 36 U1 0 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1992 VL 30 IS 3 BP 531 EP 539 DI 10.1109/36.142931 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 JA318 UT WOS:A1992JA31800012 ER PT J AU LIN, Q VESECKY, JF ZEBKER, HA AF LIN, Q VESECKY, JF ZEBKER, HA TI NEW APPROACHES IN INTERFEROMETRIC SAR DATA-PROCESSING SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB It is well established that interferometric synthetic aperture radar (SAR) images can be inverted to perform surface elevation mapping. Among the factors critical to the mapping accuracy are registration of the interfering SAR images and phase unwrapping. A novel registration algorithm is presented that determines the registration parameters through optimization. A new figure of merit is proposed that evaluates the registration result during the optimization. The phase unwrapping problem is approached through a new method involving fringe line detection. The algorithms are tested with two SEASAT SAR images of terrain near Yellowstone National Park. These images were collected on SEASAT orbits 1334 and 1420, which were very close together in space, i.e., less than 100 m. The resultant elevation map is compared with the USGS digital terrain elevation model. C1 JET PROP LAB,PASADENA,CA 91109. RP LIN, Q (reprint author), STANFORD UNIV,DEPT ELECT ENGN,STAR LAB,STANFORD,CA 94305, USA. NR 14 TC 71 Z9 94 U1 2 U2 8 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1992 VL 30 IS 3 BP 560 EP 567 DI 10.1109/36.142934 PG 8 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA JA318 UT WOS:A1992JA31800015 ER PT J AU JACKSON, TJ KOSTOV, KG SAATCHI, SS AF JACKSON, TJ KOSTOV, KG SAATCHI, SS TI ROCK FRACTION EFFECTS ON THE INTERPRETATION OF MICROWAVE EMISSION FROM SOILS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID MODEL AB Research has shown that soil properties affect the relationship that exists between microwave emission and surface soil moisture, but it has not considered how the rock fraction of the soil influences the emissivity. In this study, the effects of the rock fraction were investigated through a combination of laboratory dielectric measurements and field observation of emissivity. A series of field measurements were conducted which included soils with (35% by volume) and without rocks. Microwave brightness temperature was measured at L (21 cm) and C (6 cm) bands for both horizontal and vertical polarizations using a truck-mounted passive microwave radiometer system. Dielectric measurements were made at L band using a field portable dielectric probe. For the rock samples, the average values of the dielectric constant were 4.7 and 0.07 for the real and imaginary parts, respectively. Laboratory measurements of the real part of the dielectric constant for the soil-water mixtures matched well with values predicted using dielectric mixing models. The most important observed effect that rock fraction had was the reduction in the range of emissivity. Comparisons between observed and predicted relationships of volumetric soil moisture and emissivity showed that the effects of rock fraction are not significant in estimating the sample soil moisture when 21-cm data are used, for the rock fraction examined here. Knowing the rock fraction is only important if one wishes to know the moisture in the soil component. Data collected at 6 cm clearly showed that the presence of rocks will make this and shorter wavelengths useless as soil moisture sensors. Model studies at a 21-cm wavelength suggest that the effects of rock fraction on soil dielectric properties may be offset by increased surface roughness. C1 BULGARIAN ACAD SCI,INST ELECTR,BU-1784 SOFIA,BULGARIA. JET PROP LAB,RADAR SCI GRP,PASADENA,CA 91109. RP JACKSON, TJ (reprint author), USDA ARS,BELTSVILLE AGR RES CTR,HYDROL LAB,BELTSVILLE,MD 20705, USA. NR 16 TC 27 Z9 27 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1992 VL 30 IS 3 BP 610 EP 616 DI 10.1109/36.142939 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 JA318 UT WOS:A1992JA31800020 ER PT J AU HALL, DK FOSTER, JL CHANG, ATC AF HALL, DK FOSTER, JL CHANG, ATC TI REFLECTANCE OF SNOW AS MEASURED INSITU AND FROM SPACE IN SUB-ARCTIC AREAS IN CANADA AND ALASKA SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Note ID FRESH-WATER ICE; THEMATIC MAPPER; OPTICAL-PROPERTIES; ALBEDO; GLACIERS AB Quantitative measurement of snow reflectance from space has been possible since the launch of the Landsat Thematic Mapper (TM) in 1982. Efforts to validate the accuracy of Landsat derived reflectances are ongoing to enable mapping global snow reflectance, and eventually snow albedo, using data from future satellite sensors. Visible and near-infrared measurements of clean snow and dirty snow (both actively melting) were acquired near Yellowknife, N.W.T., Canada, in May 19" using a portable spectrometer, and the Landsat TM. Similar measurements were also acquired over snow covered glaciers in Alaska in August 1987. The in situ reflectance at nadir of the dirty snow was approximately 30% lower in the visible part of the spectrum than was the reflectance of the cleaner snow near Yellowknife. The shapes of the reflectance curves are also different, the curves for the dirty snow being flatter than the curves for the clean snow. The shape of the reflectance curves of actively melting snow near Yellowknife versus fresh snow as measured in Alaska, was similar in the visible region of the spectrum, but diverged in the near-infrared region, with the reflectance of the melting snow decreasing moreso than for fresh snow. In Alaska, the off-nadir look angle measurements of snow consistently exceeded 1.0 because of enhanced forward scattering from the snow at off-nadir angles when the sensor is facing the Sun. TM-derived reflectances acquired near Yellowknife are not directly comparable with in situ measurements because a mixture of cover types is included within each 30 x 30 m pixel. Because the variability in solar zenith angle causes major differences in absolute reflectance, the shape of the reflectance curves and the anisotropic reflectance properties are found more useful in differentiating snow type and moisture state than are actual reflectances. RP HALL, DK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,CODE 974,GREENBELT,MD 20771, USA. RI Hall, Dorothy/D-5562-2012 NR 31 TC 16 Z9 16 U1 1 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAY PY 1992 VL 30 IS 3 BP 634 EP 637 DI 10.1109/36.142947 PG 4 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA JA318 UT WOS:A1992JA31800027 ER PT J AU REED, IS TRUONG, TK CHEN, XM AF REED, IS TRUONG, TK CHEN, XM TI THE ALGEBRAIC DECODING OF THE (41, 21, 9) QUADRATIC RESIDUE CODE SO IEEE TRANSACTIONS ON INFORMATION THEORY LA English DT Article DE ERROR-CORRECTION CODING THEORY; CYCLIC CODE; QUADRATIC RESIDUE CODE; FINITE FIELD ID GOLAY CODE AB A new algebraic approach for decoding the quadratic residue (QR) codes, in particular the (41, 21, 9) QR code is presented. The key ideas behind this decoding technique are a systematic application of the Sylvester resultant method to the Newton identities associated with the code syndromes to find the error-locator polynomial, and next a method for determining error locations by solving certain quadratic, cubic and quartic equations over GF(2m) in a new way which uses Zech's logarithms for the arithmetic. The algorithms developed here for Zech's logarithms save a substantial amount of computer memory by storing only a table of the fundamental parameters instead of a complete table of Zech's logarithms. These algorithms are suitable for implementation in a programmable microprocessor or special-purpose VLSI chip. It is expected that the algebraic methods developed here can apply generally to other codes such as the BCH and Reed-Solomon codes. C1 RAND CORP,SANTA MONICA,CA 90406. MITRE CORP,BEDFORD,MA 01730. CALTECH,JET PROP LAB,COMMUN SYST RES SECT,PASADENA,CA 91109. RP REED, IS (reprint author), UNIV SO CALIF,DEPT ELECT ENGN,LOS ANGELES,CA 90089, USA. NR 10 TC 46 Z9 50 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9448 J9 IEEE T INFORM THEORY JI IEEE Trans. Inf. Theory PD MAY PY 1992 VL 38 IS 3 BP 974 EP 986 DI 10.1109/18.135639 PG 13 WC Computer Science, Information Systems; Engineering, Electrical & Electronic SC Computer Science; Engineering GA HR453 UT WOS:A1992HR45300005 ER PT J AU ELEFTHERIADES, GV REBEIZ, GM AF ELEFTHERIADES, GV REBEIZ, GM TI HIGH-GAIN STEP-PROFILED INTEGRATED DIAGONAL HORN-ANTENNAS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB Dipole excited integrated horn antennas are well established by now. Their main limitation stems from their large flare angle of 70-degrees which is inherent in the anisotropic etching process of <100> silicon wafers. The large flare-angle does not allow for integrated horns with gains higher than 13 dB and for 10-dB beamwidths less than 90-degrees. In this paper, a new step-profiled horn is proposed which reduces the effective flare angle of the horn and allows for gains in the region of 17 dB to 20 dB to be achieved. The symmetry of the horn's radiation pattern is enhanced by positioning the exciting dipole along the diagonal of the horn cavity. A specific design example is shown with a gain of 18.4 dB and a 10-dB beamwidth of 37-degrees in the E, H and 45-degrees planes. The coupling efficiency of this horn to a Gaussian beam is calculated to be 83%. An equivalent smooth envelope-horn (see text) was built at 12.1 GHz and the measured patterns agree well with theory. The integrated step-profiled horn is well suited for millimeter wave and Terahertz focal plane imaging arrays requiring a large number of elements. C1 UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109. RP ELEFTHERIADES, GV (reprint author), UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,ANN ARBOR,MI 48109, USA. NR 13 TC 9 Z9 9 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAY PY 1992 VL 40 IS 5 BP 801 EP 805 DI 10.1109/22.137381 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA HU514 UT WOS:A1992HU51400003 ER PT J AU KOOI, JW CHAN, M PHILLIPS, TG BUMBLE, B LEDUC, HG AF KOOI, JW CHAN, M PHILLIPS, TG BUMBLE, B LEDUC, HG TI A LOW-NOISE 230 GHZ HETERODYNE RECEIVER EMPLOYING .25-MU-M2 AREA NB/ALOX/NB TUNNEL-JUNCTIONS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article AB We report recent results for a full height rectangular waveguide mixer with an integrated IF matching network. Two .25-mu-m2 Nb/AlOx/Nb superconducting insulating superconducting (SIS) tunnel junctions with a current density of almost-equal-to 8500 A/cm2 and omega-RC of almost-equal-to 2.5 at 230 GHz have been tested. One of these quasiparticle tunnel junctions is currently being used at the Caltech Submillimeter Observatory in Hawaii. Detailed measurements of the receiver noise have been made from 200-290 GHz for both junctions at 4.2K. The lowest receiver noise temperatures were recorded at 239 GHz, measuring 48K DSB at 4.2K and 40K DSB at 2.1K. The 230 GHz receiver incorporates a one octave wide integrated low pass filter and matching network which transforms the pumped IF junction impedance to 50-OMEGA over a wide range of impedances. C1 JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. RP KOOI, JW (reprint author), CALTECH,1201 E CALIF BLVD,PASADENA,CA 91125, USA. NR 12 TC 38 Z9 38 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAY PY 1992 VL 40 IS 5 BP 812 EP 815 DI 10.1109/22.137383 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA HU514 UT WOS:A1992HU51400005 ER PT J AU KOLLBERG, EL TOLMUNEN, TJ FRERKING, MA EAST, JR AF KOLLBERG, EL TOLMUNEN, TJ FRERKING, MA EAST, JR TI CURRENT SATURATION IN SUBMILLIMETER WAVE VARACTORS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID DIODES AB In semiconductor; devices the speed of electrons cannot exceed.certain limits. This phenomenon will affect varactor multipliers as well as other high frequency devices where the RF current through the active part of the device is primarily displacement current. Hence, we expect at some point "saturation" of the varactor output power. We will, in this paper, discuss this phenomenon in some detail and show that it severely deteriorates the multiplier performance at higher frequencies. Single barrier varactors (SBV) should have an advantage over GaAs Schottky diode varactors because they can be fabricated on InAs and stacked in a series array, allowing for lower current densities and higher power handling. C1 JET PROP LAB,PASADENA,CA 91109. UNIV MICHIGAN,SOLID STATE ELECTR LAB,ANN ARBOR,MI 48109. RP KOLLBERG, EL (reprint author), CHALMERS UNIV TECHNOL,DEPT APPL ELECTR PHYS,S-41296 GOTHENBURG,SWEDEN. NR 11 TC 51 Z9 51 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAY PY 1992 VL 40 IS 5 BP 831 EP 838 DI 10.1109/22.137387 PG 8 WC Engineering, Electrical & Electronic SC Engineering GA HU514 UT WOS:A1992HU51400009 ER PT J AU LIENEWEG, U TOLMUNEN, TJ FRERKING, MA MASERJIAN, J AF LIENEWEG, U TOLMUNEN, TJ FRERKING, MA MASERJIAN, J TI MODELING OF PLANAR VARACTOR FREQUENCY-MULTIPLIER DEVICES WITH BLOCKING BARRIERS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID DIODES AB Models for optimization of planar frequency triplers with symmetrical C - V curves are presented. Role and limitation of various blocking barriers (oxide, Mott, heterojunction) are discussed. Devices with undoped drift regions (BIN) have moderate efficiency but a broad range of power operation, whereas devices with doped drift regions (BNN) have high efficiency in a narrow power window. In particular, an upper power limit of the BNN is caused by electron velocity saturation. Implementations in SiO2/Si and AlAs/GaAs and means for increasing the power of BNN structures are considered. RP LIENEWEG, U (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 19 TC 10 Z9 10 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAY PY 1992 VL 40 IS 5 BP 839 EP 845 DI 10.1109/22.137388 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA HU514 UT WOS:A1992HU51400010 ER PT J AU REED, IS SHIH, MT TRUONG, TK HENDON, E TUFTS, DW AF REED, IS SHIH, MT TRUONG, TK HENDON, E TUFTS, DW TI A VLSI ARCHITECTURE FOR SIMPLIFIED ARITHMETIC FOURIER-TRANSFORM ALGORITHM SO IEEE TRANSACTIONS ON SIGNAL PROCESSING LA English DT Article AB The arithmetic Fourier transform (AFT) is a number-theoretic approach to Fourier analysis which has been shown to perform competitively with the classical FFT in terms of accuracy, complexity, and speed. Theorems developed in a previous paper for the AFT algorithm are used here to derive the original AFT algorithm which Bruns found in 1903. This is shown then to yield an algorithm of less complexity and of improved performance over certain recent AFT algorithms. A VLSI architecture is suggested for this simplified AFT algorithm. This architecture uses a butterfly structure which reduces the number of additions by 25% of that used in the direct method. C1 CALTECH,JET PROP LAB,COMMUN SYST RES SECT,PASADENA,CA 91109. UNIV RHODE ISL,DEPT ELECT ENGN,KINGSTON,RI 02881. RP REED, IS (reprint author), UNIV SO CALIF,DEPT ELECT ENGN,LOS ANGELES,CA 90089, USA. NR 10 TC 12 Z9 14 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1053-587X J9 IEEE T SIGNAL PROCES JI IEEE Trans. Signal Process. PD MAY PY 1992 VL 40 IS 5 BP 1122 EP 1133 DI 10.1109/78.134475 PG 12 WC Engineering, Electrical & Electronic SC Engineering GA HR457 UT WOS:A1992HR45700010 ER PT J AU THOMAS, LD AF THOMAS, LD TI FUNCTIONAL IMPLICATIONS OF COMPONENT COMMONALITY IN OPERATIONAL SYSTEMS SO IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS LA English DT Letter AB The application of commonality in a system represents an attempt to reduce costs by reducing the number of unique components. Research in this area has primarily addressed a significant benefit of commonality, the reduction of parts inventories in assemble-to-order manufacturing systems. Likewise, in an operational system subject to component failures, spares inventories are reduced through the increased commonality of components. However, commonality tends to degrade system performance parameters, a degradation that can preclude commonality in resource constrained systems such as spacecraft. The functional impacts of component commonality on a system is addressed in a manner that allows inclusion in a commonality analysis. RP THOMAS, LD (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,EJ13,HUNTSVILLE,AL 35812, USA. NR 21 TC 11 Z9 11 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9472 J9 IEEE T SYST MAN CYB JI IEEE Trans. Syst. Man Cybern. PD MAY-JUN PY 1992 VL 22 IS 3 BP 548 EP 551 DI 10.1109/21.155954 PG 4 WC Computer Science, Cybernetics; Engineering, Electrical & Electronic SC Computer Science; Engineering GA JJ363 UT WOS:A1992JJ36300013 ER PT J AU GRAY, HR GINTY, CA AF GRAY, HR GINTY, CA TI NASA HIGH-TEMPERATURE ENGINE MATERIALS PROGRAM FOR CIVIL AERONAUTICS SO JOM-JOURNAL OF THE MINERALS METALS & MATERIALS SOCIETY LA English DT Article RP GRAY, HR (reprint author), NASA,LEWIS RES CTR,HITEMP PROJECT OFF,CLEVELAND,OH 44135, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1047-4838 J9 JOM-J MIN MET MAT S JI JOM-J. Miner. Met. Mater. Soc. PD MAY PY 1992 VL 44 IS 5 BP 12 EP 12 PG 1 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing SC Materials Science; Metallurgy & Metallurgical Engineering; Mineralogy; Mining & Mineral Processing GA HU578 UT WOS:A1992HU57800002 ER PT J AU CHADERJIAN, NM GURUSWAMY, GP AF CHADERJIAN, NM GURUSWAMY, GP TI TRANSONIC NAVIER-STOKES COMPUTATIONS FOR AN OSCILLATING WING USING ZONAL GRIDS SO JOURNAL OF AIRCRAFT LA English DT Article AB Modern jet transports and maneuvering tactical fighters operating in the transonic regime often give rise to time-dependent fluid physics that interact with flexible structural components, e.g., vortical flow, shocks, and separation. Efficient computational fluid dynamic methods are required to study such computationally intensive problems. A numerical method is presented to address this problem. Time-dependent, compressible, Navier-Stokes equations are used to simulate unsteady transonic flow about a three-dimensional rigid wing undergoing a forced periodic motion in angle of attack. An efficient, implicit, diagonal algorithm is utilized because of its low operation count per time step compared to other methods that solve systems of block matrix equations. The formal time accuracy is theoretically addressed and numerically demonstrated by comparison of computational results with experimental data. A zonal grid approach, capable of treating complex geometries, is presented and its time accuracy is demonstrated by comparing two- and three-zone computations with a single grid computation and experimental data. RP CHADERJIAN, NM (reprint author), NASA,AMES RES CTR,APPL COMP FLUIDS BRANCH,MOFFETT FIELD,CA 94035, USA. NR 0 TC 9 Z9 14 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 1992 VL 29 IS 3 BP 326 EP 335 DI 10.2514/3.46165 PG 10 WC Engineering, Aerospace SC Engineering GA HX252 UT WOS:A1992HX25200007 ER PT J AU NGUYEN, K CHOPRA, I AF NGUYEN, K CHOPRA, I TI EFFECTS OF HIGHER HARMONIC CONTROL ON ROTOR PERFORMANCE AND CONTROL LOADS SO JOURNAL OF AIRCRAFT LA English DT Article AB An analytical study, based on an advanced higher harmonic control analysis for helicopter rotor systems, is carried out to investigate the potential of higher harmonic control to improve rotor performance. The effects of higher harmonic control on the stall characteristics of rotor and blade pitch-link loads when the system is configured to suppress vibration are also examined. The analysis is based on a finite element method in space and time. A nonlinear time domain unsteady aerodynamic model is used to obtain the blade air loads, and the rotor induced inflow is calculated using a nonuniform inflow model. Correlation of the calculated rotor shaft power with experimental data is fair. For performance improvement on a three-bladed rotor, a 1-3.8% reduction in rotor power is achieved with 2-deg amplitude of 2/rev blade pitch control. For vibratory hub shear suppression, simulated results indicate that higher harmonic control may promote early blade stall. Effects of blade torsion frequencies on higher harmonic control performance are moderate, and torsionally stiff blades require less actuator power than torsionally soft blades. RP NGUYEN, K (reprint author), NASA,AMES RES CTR,ROTORCRAFT AEROMECH BRANCH,MOFFETT FIELD,CA 94035, USA. NR 0 TC 7 Z9 7 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 1992 VL 29 IS 3 BP 336 EP 342 DI 10.2514/3.46166 PG 7 WC Engineering, Aerospace SC Engineering GA HX252 UT WOS:A1992HX25200008 ER PT J AU PETLEY, DH JONES, SC AF PETLEY, DH JONES, SC TI THERMAL MANAGEMENT FOR A MACH-5 CRUISE AIRCRAFT USING ENDOTHERMIC FUEL SO JOURNAL OF AIRCRAFT LA English DT Article AB A thermal management concept for a Mach 5 cruise aircraft using noncryogenic fuel is presented. Catalytic endothermic reaction of petroleum fuel is used as the heat sink for engine cooling. A secondary closed-loop coolant circuit removes heat from the engine and transfers this heat to the catalytic reactor. Insulation on the engine now path surfaces reduces the cooling requirements. A high temperature insulation system, which is capable of a surface temperature of 4000-degrees-F (2200-degrees-C), is used for the combustor and nozzle. A complete closed-loop cooling system design is shown in detail. Main features of this system include a fuel preheater, a catalytic fuel reactor, and engine wall cooling panels. A silicone-based liquid polymer, designed for extended use at 750-degrees-F (400-degrees-C), is used as the coolant. The preheater and reactor design are based on the results of recent experimental work. The cooling panels are designed using a thermal fluid analysis computer program that was originally developed for the National Aero-Space Plane (NASP). Major components are analyzed structurally as well as thermally and weights are presented. RP PETLEY, DH (reprint author), NASA,LANGLEY RES CTR,HYPERSON TECHNOL OFF,MS 350,HAMPTON,VA 23665, USA. NR 0 TC 12 Z9 15 U1 1 U2 5 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAY-JUN PY 1992 VL 29 IS 3 BP 384 EP 389 DI 10.2514/3.46173 PG 6 WC Engineering, Aerospace SC Engineering GA HX252 UT WOS:A1992HX25200015 ER PT J AU ROSENFELD, D ATLAS, D WOLFF, DB AMITAI, E AF ROSENFELD, D ATLAS, D WOLFF, DB AMITAI, E TI BEAMWIDTH EFFECTS ON Z-R RELATIONS AND AREA-INTEGRATED RAINFALL SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID CONVECTIVE RAINFALL; SURFACE RAINFALL; RADAR; REFLECTIVITY AB The effective radar reflectivity Z(e) measured by a radar is the convolution of the actual distribution of reflectivity with the beam radiation pattern. Because of the nonlinearity between Z and rain rate R, Z(e) gives a biased estimator of R whenever the reflectivity field is nonuniform. In the presence of sharp horizontal reflectivity gradients, the measured pattern of Z(e) extends beyond the actual precipitation boundaries to produce false precipitation echoes. When integrated across the radar image of the storm, the false echo areas contribute to the sum to produce overestimates of the areal rainfall. As the range or beamwidth increases, the ratio of measured to actual rainfall increases. Beyond some range, the normal decrease of reflectivity with height dominates and the measured rainfall underestimates the actual amount. The net effect is a Z(e)-R relationship that may differ largely from that which would be obtained from consideration of the drop-size distribution alone. The range dependence is also altered significantly. The results are especially important for quantitative measurement of convective rainfall over large areas. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. JET PROP LAB,PASADENA,CA 91109. APPL RES CORP,LANDOVER,MD. RP ROSENFELD, D (reprint author), HEBREW UNIV JERUSALEM,DEPT ATMOSPHER SCI,IL-35291 JERUSALEM,ISRAEL. RI Rosenfeld, Daniel/F-6077-2016 OI Rosenfeld, Daniel/0000-0002-0784-7656 NR 23 TC 26 Z9 26 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD MAY PY 1992 VL 31 IS 5 BP 454 EP 464 DI 10.1175/1520-0450(1992)031<0454:BEOZRR>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HV478 UT WOS:A1992HV47800005 ER PT J AU GREENLEAF, JE VERNIKOS, J WADE, CE BARNES, PR AF GREENLEAF, JE VERNIKOS, J WADE, CE BARNES, PR TI EFFECT OF LEG EXERCISE TRAINING ON VASCULAR VOLUMES DURING 30 DAYS OF 6-DEGREE HEAD-DOWN BED REST SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE PLASMA VOLUME; RED CELL VOLUME; BLOOD VOLUME; BODY DENSITY; WATER BALANCE ID FLUID-ELECTROLYTE METABOLISM; ATRIAL-NATRIURETIC-FACTOR; PLASMA-VOLUME; GRADED-EXERCISE; VASOPRESSIN; RESPONSES; RENIN; OSMOLALITY; ALBUMIN; HUMANS AB Plasma and red cell volumes, body density, and water balance were measured in 19 men (32-42 yr) confined to bed rest (BR). One group (n = 5) had no exercise training (NOE), another near-maximal variable-intensity isotonic exercise for 60 min/day (ITE; n = 7), and the third near-maximal intermittent isokinetic exercise for 60 min/day (IKE; n = 7). Caloric intake was 2,678-2,840 kcal/day; mean body weight (n = 19) decreased by 0.58 +/- 0.35 (SE) kg during BR due to a negative fluid balance (diuresis) on day 1. Mean energy costs for the NOE, and IKE, and ITE regimens were 83 (3.6 +/- 0.2 ml O2.min-1.kg-1), 214 (8.9 +/- 0.5 ml.min-1.kg-1), and 446 kcal/h (18.8 +/- 1.6 ml.min-1.kg-1), respectively. Body densities within groups and mean urine volumes (1,752 - 1,846 ml/day) between groups were unchanged during BR. Resting changes in plasma volume (ml/kg) after BR were -1.5 +/- 2.3% (NS) in ITE, -14.7 +/- 2.8% (P < 0.05) in NOE, and -16.8 +/- 2.9% (P < 0.05) in IKE, and mean water balances during BR were +295, -106, and +169 ml/24 h, respectively. Changes in red cell volume followed changes in plasma volume. The significant chronic decreases in plasma volume in the IKE and NOE groups and its maintenance in the ITE group could not be accounted for by water balance or by responses of the plasma osmotic, protein, vasopressin, or aldosterone concentrations or plasma renin activity. There was close coupling between resting plasma volume and plasma protein and osmotic content. It appears that the ITE training protocol is better than the IKE protocol for maintaining plasma volume during prolonged exposure to BR. C1 LETTERMAN ARMY MED CTR,SAN FRANCISCO,CA 94129. SAN FRANCISCO STATE UNIV,DEPT BIOL SCI,SAN FRANCISCO,CA 94132. RP GREENLEAF, JE (reprint author), NASA,AMES RES CTR,DIV LIFE SCI,HUMAN GRAVITAT PHYSIOL LAB 23911,MOFFETT FIELD,CA 94035, USA. NR 29 TC 48 Z9 50 U1 1 U2 3 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD MAY PY 1992 VL 72 IS 5 BP 1887 EP 1894 PG 8 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA HU331 UT WOS:A1992HU33100034 PM 1601796 ER PT J AU FISHMAN, J BRACKETT, VG FAKHRUZZAMAN, K AF FISHMAN, J BRACKETT, VG FAKHRUZZAMAN, K TI DISTRIBUTION OF TROPOSPHERIC OZONE IN THE TROPICS FROM SATELLITE AND OZONESONDE MEASUREMENTS SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article ID SEASONAL-VARIATIONS AB Measurements from two independent satellite data sets have been used to derive the climatology of the integrated amount of ozone in the troposphere. These data have led to the finding that large amounts of ozone pollution are generated by anthropogenic activity originating from both the industrialized regions of the Northern Hemisphere and from the southern tropical regions of Africa. To verify the existence of this ozone anomaly over this region of the world, an ozonesonde capability has been established at Ascension Island (8-degrees-S, 15-degrees-W) since July 1990. According to the satellite analyses, Ascension Island is located downwind of the primary source region of this ozone pollution, which likely results from the photochemical oxidation of emissions emanating from the widespread burning of savannas and other biomass in central and southern Africa. These in-situ measurements confirm the existence of large amounts of ozone in the lower atmosphere. These first ozonesonde profiles suggest that much of the ozone generated over Africa during the 'burning season' (primarily July-October) reaches Ascension Island. These high levels of ozone in the lower troposphere become much lower by December. Elevated ozone concentrations in the middle troposphere are once again evident in February, which may be the result of biomass burning emissions being transported from western and northern Africa. C1 ST SYST CORP,HAMPTON,VA 23666. RP FISHMAN, J (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 16 TC 43 Z9 44 U1 2 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD MAY PY 1992 VL 54 IS 5 BP 589 EP 597 DI 10.1016/0021-9169(92)90099-7 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY123 UT WOS:A1992HY12300009 ER PT J AU AIKIN, AC KENDIG, DJ AF AIKIN, AC KENDIG, DJ TI TROPICAL BEHAVIOR OF MESOSPHERIC OZONE AS OBSERVED BY SMM SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article ID SOLAR MAXIMUM MISSION; EQUATORIAL MIDDLE ATMOSPHERE; SEMIANNUAL OSCILLATION; SEASONAL-VARIATION; WATER-VAPOR; GRAVITY-WAVES; PROFILES; SPECTROMETER; STRATOSPHERE; TRANSPORT AB The seasonal behavior of low latitude mesospheric ozone, as observed by the SMM satellite solar occultation experiment, is detailed for the 1985-1989 period. Annual as well as semi-annual waves are observed in the 50 70 km altitude region. In the latitude range of +/- 30-degrees the ozone phase and amplitude are functions of temperature and seasonal changes in solar flux. Temperature is the controlling factor for the equatorial region and seasonal changes in solar flux become more dominant at latitudes outside the equatorial zone (greater than +/- 15-degrees). There is a hemispheric asymmetry in the ozone annual wave in the 20 30-degrees region, with northern hemispheric ozone having a larger amplitude than southern hemispheric ozone. In this region temperature is nearly in phase with ozone in both hemispheres and is reduced in amplitude in the northern hemisphere. The equatorial region is characterized by a strong semi-annual wave in addition to the annual variation, and temperature is nearly out of phase with ozone. At all latitudes there is a larger ozone concentration at sunrise than at sunset. The sunrise sunset difference increases with increasing altitude. C1 ST SYST CORP STX,LANHAM,MD 20706. RP AIKIN, AC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 31 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD MAY PY 1992 VL 54 IS 5 BP 641 EP 654 DI 10.1016/0021-9169(92)90102-Q PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HY123 UT WOS:A1992HY12300012 ER PT J AU BACK, LH LIEM, TK KWACK, EY CRAWFORD, DW AF BACK, LH LIEM, TK KWACK, EY CRAWFORD, DW TI FLOW MEASUREMENTS IN A HIGHLY CURVED ATHEROSCLEROTIC CORONARY-ARTERY CAST OF MAN SO JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID STEADY FLOW; RESISTANCE; MODEL AB Flow visualization and wall pressure measurements were made in a polyurethane cast of a cadaver coronary artery with a significant "s" shaped reverse curvature. A sucrose solution was used to simulate the kinematic viscosity of blood, with flow rates in the physiologic range. Flow visualization demonstrated significant secondary flow patterns in the wall vicinity, which increased with increasing Reynolds number. Random dye dispersion was observed at a Reynolds number of about 400, but not at 200. Dye filament patterns in the transition between the first and second curved region were predominantly influenced by the second curved region at lower Reynolds numbers, and by the first curved region at higher Re. Local wall pressure measurements demonstrated a significant centrifugal effect with large radial pressure differences across the casting. Flow resistances for the casting were considerably greater than reference Poiseuille flow values, and increased further with pulsatile flow. C1 UNIV SO CALIF,SCH MED,LOS ANGELES,CA 90033. UNIV SO CALIF,DEPT MED,DIV CARDIOL,LOS ANGELES,CA 90089. RP BACK, LH (reprint author), JET PROP LAB,TECH STAFF,PASADENA,CA 91109, USA. NR 18 TC 14 Z9 17 U1 0 U2 5 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0148-0731 J9 J BIOMECH ENG-T ASME JI J. Biomech. Eng.-Trans. ASME PD MAY PY 1992 VL 114 IS 2 BP 232 EP 240 DI 10.1115/1.2891377 PG 9 WC Biophysics; Engineering, Biomedical SC Biophysics; Engineering GA HW421 UT WOS:A1992HW42100012 PM 1602767 ER PT J AU DELSIGNORE, DM OLIVER, DLR DEWITT, KJ AF DELSIGNORE, DM OLIVER, DLR DEWITT, KJ TI EXPERIMENTAL DEMONSTRATION OF DIFFUSOCAPILLARY FLOW IN AN OIL DROPLET SO JOURNAL OF COLLOID AND INTERFACE SCIENCE LA English DT Note C1 UNIV TOLEDO,DEPT MECH ENGN,2801 W BANCROFT,TOLEDO,OH 43606. NASA,LEWIS RES CTR,SVERDRUP TECHNOL,CLEVELAND,OH 44135. NR 5 TC 0 Z9 0 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9797 J9 J COLLOID INTERF SCI JI J. Colloid Interface Sci. PD MAY PY 1992 VL 150 IS 2 BP 584 EP 588 DI 10.1016/0021-9797(92)90227-D PG 5 WC Chemistry, Physical SC Chemistry GA HQ282 UT WOS:A1992HQ28200030 ER PT J AU BATUR, C SHARPLESS, RB DUVAL, WMB ROSENTHAL, BN SINGH, NB AF BATUR, C SHARPLESS, RB DUVAL, WMB ROSENTHAL, BN SINGH, NB TI IDENTIFICATION AND CONTROL OF A MULTIZONE CRYSTAL-GROWTH FURNACE SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID SINGLE-CRYSTALS; BRIDGMAN; CONFIGURATION AB This paper presents an intelligent adaptive control system for the control of a solid-liquid interface of a crystal while it is growing via directional solidification inside a multizone transparent furnace. The task of the process controller is to establish a user-specified axial temperature profile and to maintain a desirable interface shape. Both single-input-single-output and multi-input-multi-output adaptive pole placement algorithms have been used to control the temperature. We also describe an intelligent measurement system to assess the shape of the crystal while it is growing inside a multizone transparent furnace. A color video imaging system observes the crystal in real time, and determines the position and the shape of the interface. This information is used to evaluate the crystal growth rate, and to analyze the effects of translational velocity and temperature profiles on the shape of the interface. Creation of this knowledge base is the first step to incorporate image processing into furnace control. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. WESTINGHOUSE SCI & TECHNOL CTR,PITTSBURGH,PA 15235. RP BATUR, C (reprint author), UNIV AKRON,DEPT MECH ENGN,AKRON,OH 44325, USA. NR 13 TC 6 Z9 6 U1 0 U2 0 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 MAY PY 1992 VL 119 IS 3-4 BP 371 EP 380 DI 10.1016/0022-0248(92)90693-D PG 10 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA HV213 UT WOS:A1992HV21300024 ER PT J AU MESAROVIC, S GASPARINI, D MUJU, S MCNELIS, M AF MESAROVIC, S GASPARINI, D MUJU, S MCNELIS, M TI PROBABILITY OF CRACK-GROWTH IN POISSON FIELD OF PENNY CRACKS SO JOURNAL OF ENGINEERING MECHANICS-ASCE LA English DT Article ID STATISTICAL-ANALYSIS; MULTIAXIAL FRACTURE; FAILURE; SOLIDS AB An expression is derived for the probability of crack growth in a material with penny cracks of random size and orientation. It is assumed that crack growth occurs when the maximum local Mode I stress intensity factor, K(I)l, exceeds K(IC); the criterion is generalized for the three-dimensional problem. The location along the crack front and the magnitude of K(I)l are determined conditional on a penny crack of prescribed size and orientation. The probability distribution function of K(I)l is then computed using a derived probability density function for the crack size. The probability of crack growth is expressed as a function of four dimensionless parameters: The expected number of cracks in a volume; the expected value of the Mode I stress intensity factor for a crack normal to the direction of stress, divided by K(IC); the probability density function of a normalized crack size; and the Poisson ratio. A study that quantifies the effects of the four dimensionless parameters is presented. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP MESAROVIC, S (reprint author), CASE WESTERN RESERVE UNIV,DEPT CIVIL ENGN,CLEVELAND,OH 44106, USA. RI Mesarovic, Sinisa/B-1056-2009 OI Mesarovic, Sinisa/0000-0002-0117-426X NR 23 TC 0 Z9 0 U1 0 U2 1 PU ASCE-AMER SOC CIVIL ENGINEERS PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0733-9399 J9 J ENG MECH-ASCE JI J. Eng. Mech.-ASCE PD MAY PY 1992 VL 118 IS 5 BP 961 EP 978 DI 10.1061/(ASCE)0733-9399(1992)118:5(961) PG 18 WC Engineering, Mechanical SC Engineering GA HP998 UT WOS:A1992HP99800007 ER PT J AU MCCANN, RS JOHNSTON, JC AF MCCANN, RS JOHNSTON, JC TI LOCUS OF THE SINGLE-CHANNEL BOTTLENECK IN DUAL-TASK INTERFERENCE SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Article ID CHOICE REACTION-TIME; STIMULUS-RESPONSE COMPATIBILITY; IRRELEVANT DIRECTIONAL CUE; S-R COMPATIBILITY; OVERLAPPING TASKS; ATTENTION; INFORMATION; DURATION AB Two experiments used the locus-of-cognitive-slack method to determine whether dual-task interference occurs before or after the response selection stage. The experiments used the overlapping tasks paradigm, in which two signals, each requiring a different speeded choice response, are presented in rapid succession. In Experiment 1, stimulus-response (S-R) compatibility was manipulated by varying whether Task 2 stimuli were mapped onto their responses by a rule or arbitrarily. Compatibility effects were additive with the effects of degree of task overlap, manipulated by varying the stimulus onset asynchrony between the signals. Experiment 2 examined 2 additional forms of S-R compatibility: symbolic compatibility (arrows vs. letters) and spatial compatibility (the "Simon" effect). Effects of symbolic compatibility were additive with effects of degree of task overlap, whereas the effects of spatial compatibility and degree of task overlap were underadditive. It is argued that only a central-bottleneck model provides a consistent account of these results. The nature of the central bottleneck is considered. C1 STERLING FED SYST,PALO ALTO,CA. RP MCCANN, RS (reprint author), NASA,AMES RES CTR,MAIL STOP 262-6,MOFFETT FIELD,CA 94035, USA. NR 64 TC 230 Z9 232 U1 0 U2 11 PU AMER PSYCHOLOGICAL ASSOC PI WASHINGTON PA 750 FIRST ST NE, WASHINGTON, DC 20002-4242 SN 0096-1523 J9 J EXP PSYCHOL HUMAN JI J. Exp. Psychol.-Hum. Percept. Perform. PD MAY PY 1992 VL 18 IS 2 BP 471 EP 484 DI 10.1037//0096-1523.18.2.471 PG 14 WC Psychology; Psychology, Experimental SC Psychology GA HT255 UT WOS:A1992HT25500012 ER PT J AU MANKBADI, RR LIU, JTC AF MANKBADI, RR LIU, JTC TI NEAR-WALL RESPONSE IN TURBULENT SHEAR FLOWS SUBJECTED TO IMPOSED UNSTEADINESS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID PIPE-FLOW; BOUNDARY-LAYER; PULSATING FLOW; DISTORTION; BEHAVIOR AB Rapid-distortion theory is adapted to introduce a truly unsteady closure into a simple phenomenological turbulence model in order to describe the unsteady response of a turbulent wall layer exposed to a temporarily oscillating pressure gradient. The closure model is built by taking the ratio of turbulent shear stress to turbulent kinetic energy to be a function of the effective strain. The latter accounts for the history of the flow. The computed unsteady velocity fluctuations and modulated turbulent stresses compare favourably in the 'non-quasi-steady' frequency range, where quasi-steady assumptions would fail. This suggests that the concept of rapid distortion is especially appropriate for unsteady flows. This paper forms the basis for acoustical studies of the problem to be reported elsewhere. C1 BROWN UNIV, DIV ENGN, PROVIDENCE, RI 02912 USA. LAB AEROTHERM, CNRS, F-92190 MEUDON, FRANCE. RP MANKBADI, RR (reprint author), NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. NR 43 TC 22 Z9 22 U1 0 U2 2 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 EI 1469-7645 J9 J FLUID MECH JI J. Fluid Mech. PD MAY PY 1992 VL 238 BP 55 EP 71 DI 10.1017/S0022112092001630 PG 17 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA HX224 UT WOS:A1992HX22400003 ER PT J AU ERLEBACHER, G HUSSAINI, MY SPEZIALE, CG ZANG, TA AF ERLEBACHER, G HUSSAINI, MY SPEZIALE, CG ZANG, TA TI TOWARD THE LARGE-EDDY SIMULATION OF COMPRESSIBLE TURBULENT FLOWS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID NUMERICAL-SIMULATION AB New subgrid-scale models for the large-eddy simulation of compressible turbulent flows are developed and tested based on the Favre-filtered equations of motion for an ideal gas. A compressible generalization of the linear combination of the Smagorinsky model and scale-similarity model, in terms of Favre-filtered fields, is obtained for the subgrid-scale stress tensor. An analogous thermal linear combination model is also developed for the subgrid-scale heat flux vector. The two dimensionless constants associated with these subgrid-scale models are obtained by correlating with the results of direct numerical simulations of compressible isotropic turbulence performed on a 96(3) grid using Fourier collocation methods. Extensive comparisons between the direct and modelled subgrid-scale fields are provided in order to validate the models. A large-eddy simulation of the decay of compressible isotropic turbulence - conducted on a coarse 32(3) grid - is shown to yield results that are in excellent agreement with the fine-grid direct simulation. Future applications of these compressible subgrid-scale models to the large-eddy simulation of more complex supersonic flows are discussed briefly. RP ERLEBACHER, G (reprint author), NASA,LANGLEY RES CTR,ICASE,HAMPTON,VA 23665, USA. NR 35 TC 294 Z9 301 U1 4 U2 23 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD MAY PY 1992 VL 238 BP 155 EP 185 DI 10.1017/S0022112092001678 PG 31 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA HX224 UT WOS:A1992HX22400007 ER PT J AU BURKE, WJ AGGSON, TL MAYNARD, NC HOEGY, WR HOFFMAN, RA CANDY, RM LIEBRECHT, C RODGERS, E AF BURKE, WJ AGGSON, TL MAYNARD, NC HOEGY, WR HOFFMAN, RA CANDY, RM LIEBRECHT, C RODGERS, E TI EFFECTS OF A LIGHTNING DISCHARGE DETECTED BY THE DE-2 SATELLITE OVER HURRICANE DEBBIE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INDUCED ELECTRON-PRECIPITATION; EXPLOSIVE SPREAD-F; ACTIVE THUNDERSTORM; IONOSPHERE; ATMOSPHERE; FIELDS; PERTURBATION; RADIATION; MIDDLE; MODEL AB We report the satellite observation of a large, approximately 40 mV m-1, transient electric field disturbance over Hurricane Debbie in September 1982. The event lasted less than a second and correlated closely with a burst of highly field-aligned, upward moving electrons with nearly 1 keV of energy. The electric field event is viewed as a spheric disturbance from a lightning discharge in the active weather system located beneath the satellite. A spheric interpretation of the observed electric field transient is consistent with a subsequent observation of energetic electrons precipitating from the radiation belts. Measured quasi-dc electric fields and cold plasma density variations are only roughly consistent with model predictions for ULF wave propagation from a storm system to the ionosphere. To understand this first observation of upward moving electrons in the ionosphere associated with a lightning event, we compare the several mechanisms for electron acceleration by electric fields with components (E parallel-to) along the magnetic field. In our scenario. "runaway" electrons were accelerated in approximately 1 ms by a downward directed E parallel-to pulse of approximately 1 V m-1 magnitude. Such fields can result from rapidly exposed, negative space charges near the tops of clouds during positive cloud-to-ground discharges. High-frequency Fourier components of the E parallel-to pulse must propagate through the low-conducting nighttime atmosphere to the ionosphere with little dissipation. C1 ARC PROF SERV GRP, ROCKVILLE, MD 20850 USA. STX CORP, GREENBELT, MD 20771 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP PHILLIPS LAB, GEOPHYS DIRECTORATE, BEDFORD, MA 01731 USA. NR 44 TC 37 Z9 37 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1992 VL 97 IS A5 BP 6359 EP 6367 DI 10.1029/92JA00305 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HT743 UT WOS:A1992HT74300013 ER PT J AU DELCOURT, DC MOORE, TE AF DELCOURT, DC MOORE, TE TI PRECIPITATION OF IONS INDUCED BY MAGNETOTAIL COLLAPSE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SINGLE-PARTICLE ORBITS; TIME RING CURRENT; MAGNETOSPHERIC SUBSTORMS; ENERGETIC PARTICLES; POLAR IONOSPHERE; ELECTRIC-FIELDS; MAGNETIC-FIELD; PLASMA SHEET; ACCELERATION; ENERGIZATION AB The precipitation of ions triggered by dipolarization of magnetospheric field lines during substorm expansion phase is examined by means of single-particle codes. As large but short-lived electric fields develop and particles experience transient nonadiabatic motions, it is demonstrated that "de-trapping" of inner plasma sheet populations can be achieved either via damping of magnetic moment or impulsive accelerations in the parallel direction. It is shown that the former precipitation mechanism results from phasing between gyromotion and the surging electric field. It preferentially affects heavy and low-charge state ions which can display large de-energization rates within a cyclotron period. The latter mechanism rather favors the loss of lighter and/or higher-charge state ions which am less sensitive to temporal nonadiabaticity. In this case, injection into the loss cone may result from enhanced curvature related acceleration. As this latter acceleration occurs on the dipolarization time scale, it affects a limited amount of plasma sheet populations, namely those intercepting the region of maximum curvature at the time of peak induced electric field. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP DELCOURT, DC (reprint author), CTR RECH PHYS ENVIRONN,F-94107 ST MAUR FOSSES,FRANCE. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 27 TC 18 Z9 18 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAY 1 PY 1992 VL 97 IS A5 BP 6405 EP 6415 DI 10.1029/91JA03142 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HT743 UT WOS:A1992HT74300017 ER PT J AU TOLSON, RH HUANG, JK AF TOLSON, RH HUANG, JK TI INTEGRATED CONTROL OF THERMALLY DISTORTED LARGE SPACE ANTENNAS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SHAPE CONTROL; SYSTEMS AB The objective of this paper is to develop a control system design method that 1) recognizes the time dependence of the thermal distortion due to orbital motion and 2) controls variables that are directly related to far-field performance for Earth-pointing space antennas. The first objective is accomplished by expanding the distortion into principal components that are orthogonal in space and time. Actuator strokes become a linear combination of the time-dependent components. The spatial components provide a natural space in which to determine the optimal actuator locations and act as basis vectors for extrapolating sensor measurements to the entire antenna surface. The approach for the second objective is to expand the far zone electric field in a Zernike-Bessel series. The coefficients of this series provide a reliable measure of far-field performance and a natural cost function for designing the control system. The method accommodates tapered feeds and arbitrary polarizations. Simulations are performed for a geosynchronous radiometer to determine the effectiveness of the control system under variations in solar geometry, structure materials, and thermal properties. C1 OLD DOMINION UNIV,DEPT MECH ENGN & MECH,NORFOLK,VA 23529. RP TOLSON, RH (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 269,HAMPTON,VA 23665, USA. NR 16 TC 6 Z9 8 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1992 VL 15 IS 3 BP 605 EP 614 DI 10.2514/3.20881 PG 10 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA HU736 UT WOS:A1992HU73600008 ER PT J AU BRAUN, RD POWELL, RW AF BRAUN, RD POWELL, RW TI PREDICTOR-CORRECTOR GUIDANCE ALGORITHM FOR USE IN HIGH-ENERGY AEROBRAKING SYSTEM STUDIES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT CONF ON GUIDANCE, NAVIGATION, AND CONTROL CY AUG 20-22, 1990 CL PORTLAND, OR SP AMER INST AERONAUT & ASTRONAUT AB A three-degree-of-freedom predictor-corrector guidance algorithm is developed specifically for use in high energy aerobraking performance evaluations. This paper presents both the development and capabilities of this guidance algorithm as applied to the design of manned Mars aerobraking vehicles. Atmospheric simulations are performed to demonstrate the applicability of this algorithm and to evaluate the effects of off-nominal conditions upon the mission. The off-nominal conditions simulated result from atmospheric density and aerodynamic characteristic mispredictions. The guidance algorithm also provides relief from the high deceleration levels typically encountered in a high-energy aerobraking mission profile. Through this analysis, bank-angle modulation is shown to be an effective means of providing deceleration relief. Furthermore, the capability of the guidance algorithm to manage off-nominal vehicle aerodynamic and atmospheric density variations is demonstrated. RP BRAUN, RD (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 14 TC 20 Z9 21 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1992 VL 15 IS 3 BP 672 EP 678 DI 10.2514/3.20890 PG 7 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA HU736 UT WOS:A1992HU73600017 ER PT J AU SCHROEDER, JA MERRICK, VK AF SCHROEDER, JA MERRICK, VK TI CONTROL AND DISPLAY COMBINATIONS FOR BLIND VERTICAL LANDINGS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID AIRCRAFT; FLIGHT AB Several hover control and display concepts were evaluated in flight on a variable-stability helicopter. The control and display concepts enable precise hover maneuvers, station keeping, and vertical shipboard landings in zero-visibility conditions and until now have been evaluated only in piloted simulations. A new display design method is presented that attempts to attain the same pilot-vehicle performance regardless of the level of control augmentation. The display design method was first examined analytically with the control dynamics in the context of the pilot's desired guidance strategy. Then, while fully hooded, three pilots performed landing-pad captures followed by vertical landings with attitude-rate-command/attitude-hold, attitude-command/attitude-hold, and translational-velocity-command control systems. Of the 28 piloted blind landings, 25 were within 5 ft and 14 were within 2 ft of the specified touchdown point. RP SCHROEDER, JA (reprint author), NASA,AMES RES CTR,FLIGHT DYNAM & CONTROLS BRANCH,MOFFETT FIELD,CA 94035, USA. NR 36 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAY-JUN PY 1992 VL 15 IS 3 BP 751 EP 760 DI 10.2514/3.20901 PG 10 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA HU736 UT WOS:A1992HU73600028 ER PT J AU KUMAR, KS WHITTENBERGER, JD AF KUMAR, KS WHITTENBERGER, JD TI INTERDIFFUSION BETWEEN THE L12 TRIALUMINIDES AL66TI25MN9 AND AL67TI25CR8 SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID DIFFUSION AB Interdiffusion coefficients (D) were determined in the temperature range 1373 K-1073 K (0.85 T(m) - 0.65 T(m)) from concentration-distance profiles that were generated from Al66Ti25Mn9/Al67Ti25Cr8 diffusion couples. As both of these materials are completely soluble in one another, the couples were treated as pseudobinaries (particularly because the Ti and Al levels were similar), and the Matano approach was used to calculate diffusion coefficients. The variation in D with composition was determined and a minimum was noted at intermediate temperatures and a relative Mn concentration of 0.5. A maximum in activation energy for interdiffusion was also noted at this concentration where Q almost-equal-to 350 kJ/mol. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP KUMAR, KS (reprint author), MARTIN MARIETTA CORP LABS,BALTIMORE,MD 21227, USA. NR 10 TC 7 Z9 7 U1 0 U2 0 PU MATERIALS RESEARCH SOCIETY PI PITTSBURGH PA 9800 MC KNIGHT ROAD SUITE 327, PITTSBURGH, PA 15237 SN 0884-2914 J9 J MATER RES JI J. Mater. Res. PD MAY PY 1992 VL 7 IS 5 BP 1043 EP 1045 DI 10.1557/JMR.1992.1043 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA HT106 UT WOS:A1992HT10600001 ER PT J AU IQBAL, MA AF IQBAL, MA TI EFFICIENT ALGORITHMS FOR DILATED MAPPINGS OF BINARY-TREES SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP IQBAL, MA (reprint author), UNIV ENGN & TECHNOL,DEPT ELECT ENGN,DIV COMP ENGN,LAHORE,PAKISTAN. NR 8 TC 0 Z9 0 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD MAY PY 1992 VL 15 IS 1 BP 75 EP 78 DI 10.1016/0743-7315(92)90060-Z PG 4 WC Computer Science, Theory & Methods SC Computer Science GA HV093 UT WOS:A1992HV09300006 ER PT J AU CUCINOTTA, FA TOWNSEND, LW WILSON, JW AF CUCINOTTA, FA TOWNSEND, LW WILSON, JW TI INCLUSIVE INELASTIC-SCATTERING OF HEAVY-IONS IN THE INDEPENDENT PARTICLE MODEL SO JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS LA English DT Article ID QUARK-MODEL; NUCLEI; COLLISIONS AB We consider the inclusive inelastic scattering of heavy ions using the Glauber model and the independent particle approximation. Inclusive inelastic distributions for projectile excitation of the target and total inelastic scattering, where all projectile and target excited states are summed, are discussed using closure. The total inelastic distribution when integrated is shown to be equivalent to the absorption cross section found from applying the optical theorem to the elastic scattering amplitude in the coherent approximation. Calculations are presented for several heavy-ion pairs using realistic nuclear densities in a large mass number approximation. RP CUCINOTTA, FA (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 19 TC 4 Z9 4 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0954-3899 J9 J PHYS G NUCL PARTIC JI J. Phys. G-Nucl. Part. Phys. PD MAY PY 1992 VL 18 IS 5 BP 889 EP 901 DI 10.1088/0954-3899/18/5/016 PG 13 WC Physics, Nuclear; Physics, Particles & Fields SC Physics GA HU144 UT WOS:A1992HU14400016 PM 11537102 ER PT J AU HAVENS, SJ HERGENROTHER, PM AF HAVENS, SJ HERGENROTHER, PM TI POLYIMIDES CONTAINING CARBONYL AND ETHER CONNECTING GROUPS .4. SO JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY LA English DT Letter DE POLYIMIDES; FILMS; HIGH TEMPERATURE POLYMERS AND POLYAMIDE ACIDS C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. NR 11 TC 6 Z9 6 U1 1 U2 4 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-624X J9 J POLYM SCI POL CHEM JI J. Polym. Sci. Pol. Chem. PD MAY PY 1992 VL 30 IS 6 BP 1209 EP 1212 DI 10.1002/pola.1992.080300630 PG 4 WC Polymer Science SC Polymer Science GA HN862 UT WOS:A1992HN86200030 ER PT J AU ARYA, VK AF ARYA, VK TI NONLINEAR STRUCTURAL-ANALYSIS OF CYLINDRICAL THRUST CHAMBERS USING VISCOPLASTIC MODELS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB Elevated temperature and pressure levels are required for improving the performance of the Space Shuttle Main Engine (SSME). At these elevated temperatures, the thrust chamber of the engine experiences significant inelastic strains. For an accurate estimation of the life of the chambers and to predict their progressive deformation with the number of loading cycles, a realistic stress-strain analysis for the components must be made. This paper presents the results of a viscoplastic stress-strain analysis of a cylindrical thrust chamber used in experiments. The experiments were designed to simulate the SSME operating conditions. The inelastic strain was calculated by using a viscoplastic model developed by Freed and Verrilli, and the quasi-three-dimensional structural analysis was performed by using the finite element program MARC. The temperatures and pressures were calculated by using the loading cycles of experiments, and these temperatures and pressures were used in the computations. The deformed shape of the component was predicted after the end of each loading cycle. The predicted shape qualitatively replicated the deformed shape of the component as observed in experiments. The results indicate that the use of viscoplastic models for structural analysis may lead to more realistic life assessments of experimental thrust chambers. RP ARYA, VK (reprint author), UNIV TOLEDO,NASA,DEPT MECH ENGN,TOLEDO,OH 43606, USA. NR 11 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1992 VL 8 IS 3 BP 598 EP 604 DI 10.2514/3.23520 PG 7 WC Engineering, Aerospace SC Engineering GA HU330 UT WOS:A1992HU33000012 ER PT J AU BRAUN, MJ CANACCI, VA HENDRICKS, RC AF BRAUN, MJ CANACCI, VA HENDRICKS, RC TI FLOW VISUALIZATION AND MOTION ANALYSIS FOR A SERIES OF 4 SEQUENTIAL BRUSH SEALS SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT 26TH JOINT PROPULSION CONF CY JUL 10-18, 1990 CL ORLANDO, FL SP AMER INST AERONAUT & ASTRONAUT, SOC AUTOMOT ENGINEERS, AMER SOC MECH ENGINEERS, AMER SOC ENGN EDUC AB Applying the full-flowfield-tracking (FFFT) method, the flow patterns and the accompanying fluid velocities inside a series of brushes were nonintrusively determined and graphically reconstructed. The visualized flowfield, Braun et al. 1,2 revealed regions that are characteristically river jetting, vortical, crossflow, and exist upstream, downstream, or within the seal. These flows are especially engendered by variations of fiber void that are spatial and temporal and affect changes in seal leakage and stability. The deformation of the upper half of each of the four sequential brushes as a function of upstream pressure and mass flow was determined. The axial pressure variation across the set of four brushes and the mass flow as a function of the pressure drops are also presented. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BRAUN, MJ (reprint author), UNIV AKRON,DEPT MECH ENGN,AKRON,OH 44325, USA. NR 12 TC 5 Z9 5 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1992 VL 8 IS 3 BP 697 EP 702 DI 10.2514/3.23534 PG 6 WC Engineering, Aerospace SC Engineering GA HU330 UT WOS:A1992HU33000026 ER PT J AU MENEES, GP ADELMAN, HG CAMBIER, JL BOWLES, JV AF MENEES, GP ADELMAN, HG CAMBIER, JL BOWLES, JV TI WAVE COMBUSTORS FOR TRANS-ATMOSPHERIC VEHICLES SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The wave combustor is an air-breathing hypersonic propulsion system which utilizes shock and detonation waves to enhance fuel-air mixing and combustion in supersonic flow. In this concept, an oblique shock wave in the combustor can act as a flameholder by increasing the pressure and temperature of the air-fuel mixture and thereby decreasing the ignition delay. If the oblique shock is sufficiently strong, then the combustion front and the shock wave can couple into a detonation wave. In this case, combustion occurs almost instantaneously in a thin zone behind the wave front. The result is a shorter, lighter engine compared to the scramjet. This engine, which is called the oblique detonation wave engine (ODWE), can then be utilized to provide a smaller, lighter vehicle or to provide a higher payload capability for a given vehicle weight. An analysis of the performance of a conceptual trans-atmospheric vehicle (TAV) powered by an ODWE is given here. C1 ELORET INST,PALO ALTO,CA 94306. RP MENEES, GP (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 19 TC 10 Z9 10 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1992 VL 8 IS 3 BP 709 EP 713 DI 10.2514/3.23536 PG 5 WC Engineering, Aerospace SC Engineering GA HU330 UT WOS:A1992HU33000028 ER PT J AU KUMAR, A SINGH, DJ TREXLER, CA AF KUMAR, A SINGH, DJ TREXLER, CA TI NUMERICAL STUDY OF THE EFFECTS OF REVERSE SWEEP ON SCRAMJET INLET PERFORMANCE SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT 26TH JOINT PROPULSION CONF CY JUL 10-18, 1990 CL ORLANDO, FL SP AMER INST AERONAUT & ASTRONAUT, SOC AUTOMOT ENGINEERS, AMER SOC MECH ENGINEERS, AMER SOC ENGN EDUC AB A comparative numerical study of performance parameters of a similar and an opposite sweep sidewall compression inlet is made. The focus of the study is the investigation of the impact of alternate backward-forward sweep on the compression sidewalls as opposed to backward sweep on all the sidewalls. Two equivalent scramjet inlet configurations are designed for this purpose. These inlets have the same wetted areas of compression and expansion and same height and width; but in one inlet all the compression surfaces are swept back (similar sweep inlet), whereas in the other inlet, alternate surfaces are swept backward and forward (opposite sweep inlet). The cowl closure in both cases begins at the start of the throat region. A three-dimensional Navier-Stokes code is used to calculate the flow through these inlets. Results of these calculations are used to compare the two designs for their performance and flow quality. Effects of boundary-layer ingestion on the performance and overall flow features are also investigated. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23666. NASA,LANGLEY RES CTR,DIV FLUID MECH,HYPERSON PROP BRANCH,HAMPTON,VA 23665. RP KUMAR, A (reprint author), NASA,LANGLEY RES CTR,DIV FLUID MECH,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23665, USA. NR 7 TC 6 Z9 7 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAY-JUN PY 1992 VL 8 IS 3 BP 714 EP 719 DI 10.2514/3.23537 PG 6 WC Engineering, Aerospace SC Engineering GA HU330 UT WOS:A1992HU33000029 ER PT J AU GOORVITCH, D GALANT, DC AF GOORVITCH, D GALANT, DC TI SCHRODINGERS RADIAL EQUATION - SOLUTION BY EXTRAPOLATION SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID BOUNDARY AB Combining an appropriate finite difference method with iterative extrapolation to the limit results in a simple, highly accurate, numerical method for solving a one-dimensional Schrodinger's equation appropriate for a diatomic molecule. This numerical procedure has several distinct advantages over the more conventional methods such as Numerov's method or the method of finite differences without extrapolation. The advantages are the following: (i) initial guesses for the term values are not needed; (ii) the algorithm is easy to implement, has a firm mathematical foundation and provides error estimates; (iii) the method is relatively less sensitive to round-off error since a small number of mesh points is used and, hence, can be implemented on small computers; (iv) the method is faster for equivalent accuracy. We demonstrate the advantages of the present algorithm by solving Schrodinger's equation for (a) a Morse potential function appropriate for HCI and (b) a numerically derived Rydberg-Klein-Rees potential function for the X1-SIGMA+ state of CO. A direct comparison of the results for the X1-SIGMA+ state of CO is made with results obtained using Numerov's method. C1 NASA,AMES RES CTR,DIV INFORMAT SYST,MOFFETT FIELD,CA 94035. RP GOORVITCH, D (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 17 TC 11 Z9 11 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD MAY PY 1992 VL 47 IS 5 BP 391 EP 399 DI 10.1016/0022-4073(92)90040-B PG 9 WC Optics; Spectroscopy SC Optics; Spectroscopy GA HZ288 UT WOS:A1992HZ28800009 ER PT J AU BRAUN, RD POWELL, RW LYNE, JE AF BRAUN, RD POWELL, RW LYNE, JE TI EARTH AEROBRAKING STRATEGIES FOR MANNED RETURN FROM MARS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Earth-return entry corridor analyses are performed to evaluate the atmospheric flight environment of manned return from Mars. Trajectory and performance differences between aerocapture and direct entry are assessed and quantified in terms of the required aerobrake lift-drag ratio (L/D), stagnation-point heating, and the significance of off-nominal atmospheric conditions. The Earth-return aerobraking scenarios compared are 1) aerocapture into a phasing orbit with a 24-h period, 2) aerocapture into a 500-km circular orbit, 3) and direct entry to splashdown. No significant differences between aerocapture to a 500-km circular orbit and direct entry were observed in terms of aerobrake L/D requirements, maximum deceleration, or peak stagnation-point heat rate. The importance of parking orbit selection is demonstrated for low entry velocity Earth-return missions from Mars and missions returning from the Moon. Additionally, a stagnation-point heating analysis revealed that in all cases the peak heat rate is large enough to require an ablative thermal protection system for manned return from Mars. However, for entry velocities of 12.5 km/s and less, the heating environment is of the same order of magnitude as that experienced during the Apollo program. To perform the entry analysis, two predictor-corrector guidance design strategies were developed. Use of a predictor-corrector technique was shown to provide adequate flight margin for managing off-nominal atmospheric conditions. C1 ELORET INST,PALO ALTO,CA 94303. RP BRAUN, RD (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,VEHICLE SYST BRANCH,HAMPTON,VA 23665, USA. RI Lyne, James/E-6363-2011 NR 21 TC 10 Z9 10 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1992 VL 29 IS 3 BP 297 EP 304 DI 10.2514/3.26351 PG 8 WC Engineering, Aerospace SC Engineering GA HZ095 UT WOS:A1992HZ09500001 ER PT J AU MITCHELTREE, RA SHEBALIN, JV AF MITCHELTREE, RA SHEBALIN, JV TI PLASMADYNAMIC EFFECTS IN THERMOCHEMICAL NONEQUILIBRIUM AEROBRAKE FLOWS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Modifications to the governing equations of thermochemical nonequilibrium hypersonic flow to include plasmadynamic effects are presented. Closure of the resulting equation set requires solution of the magnetic induction equation as an additional field equation. The magnetic field about a 1.1-m nose-radius aerobrake entering the Earth's atmosphere at 80 km altitude and traveling 12 km/s is computed. The result of coupling the additional terms into the Langley Aerothermodynamics Upwind Relaxation Algorithm (LAURA) indicates that plasmadynamic effects are negligible for this two-temperature Mars-return aerobraking simulation. The electromagnetic effects are limited to a small increase in vibrational-electronic temperature in the shock precursor region that does not translate to any change in the properties within the shock layer. A two-temperature solution for a lunar return aerobraking case likewise does not predict any important effects on the flowfield. Arguments are also presented to support the same conclusions for three-temperature solutions. C1 NASA,LANGLEY RES CTR,ANTENNA & MICROWAVE RES BRANCH,HAMPTON,VA 23665. RP MITCHELTREE, RA (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 19 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1992 VL 29 IS 3 BP 319 EP 326 DI 10.2514/3.26354 PG 8 WC Engineering, Aerospace SC Engineering GA HZ095 UT WOS:A1992HZ09500004 ER PT J AU RILEY, CJ DEJARNETTE, FR AF RILEY, CJ DEJARNETTE, FR TI ENGINEERING AERODYNAMIC HEATING METHOD FOR HYPERSONIC FLOW SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID RATES AB A capability to calculate surface heating rates has been incorporated in an approximate three-dimensional inviscid technique. Surface streamlines are calculated from the inviscid solution, and the axisymmetric analog is then used along with a set of approximate convective-heating equations to compute the surface heat transfer. The method is applied to blunted axisymmetric and three-dimensional elliptic cones at angle of attack for the laminar flow of a perfect gas. The method is also applicable to turbulent and equilibrium-air conditions. The present technique predicts surface heating rates that compare favorably with experimental (ground-test and flight) data and numerical solutions of the Navier-Stokes and viscous shock-layer equations. The new technique represents a significant improvement over current engineering aerothermal methods with only a modest increase in computational effort. C1 N CAROLINA STATE UNIV,DEPT MECH & AEROSP ENGN,RALEIGH,NC 27695. RP RILEY, CJ (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,MAIL STOP 336,HAMPTON,VA 23665, USA. NR 25 TC 8 Z9 10 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1992 VL 29 IS 3 BP 327 EP 334 DI 10.2514/3.26355 PG 8 WC Engineering, Aerospace SC Engineering GA HZ095 UT WOS:A1992HZ09500005 ER PT J AU COLE, SR HENNING, TL AF COLE, SR HENNING, TL TI BUFFET RESPONSE OF A HAMMERHEAD LAUNCH VEHICLE WIND-TUNNEL MODEL SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A wind-tunnel test of a 1/10th-scale Atlas-Centaur I launch vehicle model was conducted in the NASA Langley Transonic Dynamics Tunnel. The model was aeroelastically scaled to simulate flight bending modes using a partial mode technique. Several payload fairing configurations were tested at various angles of attack. No aeroelastic instabilities were found, and each configuration was generally more sensitive to Mach number variations than changes in angle of attack. Small length-to-diameter fairing ratios produced changes in buffet response in the second bending mode configuration. Additional testing was performed with vertical rods attached to the sting support to reduce the effects of mechanical vibration induced through the facility. The first flight of the Atlas-Centaur I vehicle successfully occurred on July 25, 1990, and the flight response was found to be well within the 3-sigma level of the wind-tunnel data. C1 GEN DYNAM CORP,DIV SPACE SYST,SAN DIEGO,CA 92138. RP COLE, SR (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,CONFIGURAT AEROELAST BRANCH,HAMPTON,VA 23665, USA. NR 9 TC 4 Z9 5 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1992 VL 29 IS 3 BP 379 EP 385 DI 10.2514/3.26362 PG 7 WC Engineering, Aerospace SC Engineering GA HZ095 UT WOS:A1992HZ09500012 ER PT J AU FARMER, JT WAHLS, DM WRIGHT, RL TAHERNIA, AL AF FARMER, JT WAHLS, DM WRIGHT, RL TAHERNIA, AL TI THERMAL DISTORTION ANALYSIS OF AN ANTENNA-SUPPORT TRUSS IN GEOSYNCHRONOUS ORBIT SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The effects of the geosynchronous thermal environment on the surface accuracy of a tetrahedral-truss support structure for a high-frequency microwave antenna concept for Earth-science monitoring have been studied. The thermal environment and the slow rotation of the spacecraft relative to the Sun result in long exposure to both heating and cooling conditions and, consequently, in severe temperature extremes. Resulting transient temperatures ranged from 150 to - 180-degrees-C and were strongly influenced by the shadow cast by the reflector surface. The use of truss element surface coatings achieved mixed success in alleviating thermal problems. Multilayer insulation or a Sun shield worked best in reducing surface distortions, but the distortions still exceeded the required surface accuracy. Surface accuracy requirements could only be met by customization of surface coatings and element expansion characteristics. C1 TRW CO INC,DIV SPACE SYST,VEHICLE ANAL BRANCH,WASHINGTON,DC 20546. RP FARMER, JT (reprint author), NASA,LANGLEY RES CTR,SPACE STN FREEDOM OFF,HAMPTON,VA 23665, USA. NR 10 TC 7 Z9 7 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1992 VL 29 IS 3 BP 386 EP 393 DI 10.2514/3.26363 PG 8 WC Engineering, Aerospace SC Engineering GA HZ095 UT WOS:A1992HZ09500013 ER PT J AU POE, CC AF POE, CC TI IMPACT DAMAGE AND RESIDUAL TENSION STRENGTH OF A THICK GRAPHITE EPOXY ROCKET MOTOR CASE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Impacters of various masses were dropped from various heights onto thick graphite/epoxy filament-wound cylinders. The cylinders represented filament-wound cases (FWC) made for the booster motors of the Space Shuttle. Tups of various shapes were affixed to the impacters. Some of the cylinders were filled with inert propellant, and some were empty. The cylinders were impacted numerous times around the circumference and then cut into tension coupons, each containing an impact site. The size of the damage and the residual tension strength were measured. For hemispherical tups, strength was reduced as much as 30% by nonvisible damage. The damage consisted of matrix cracking and broken fibers. Analytical methods were used to predict the damage and residual tension strength. A factor of safety to account for nonvisible damage was determined. For corner and rod shaped tups, any damage that resulted in strength loss was readily visible. This paper is a summary of that work. RP POE, CC (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 188E,HAMPTON,VA 23665, USA. NR 23 TC 3 Z9 3 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAY-JUN PY 1992 VL 29 IS 3 BP 394 EP 404 DI 10.2514/3.26364 PG 11 WC Engineering, Aerospace SC Engineering GA HZ095 UT WOS:A1992HZ09500014 ER PT J AU ROMBACH, HD ULERY, BT VALETT, JD AF ROMBACH, HD ULERY, BT VALETT, JD TI TOWARD FULL LIFE-CYCLE CONTROL - ADDING MAINTENANCE MEASUREMENT TO THE SEL SO JOURNAL OF SYSTEMS AND SOFTWARE LA English DT Article ID SOFTWARE AB Organization-wide measurement of software products and processes is needed to establish full life cycle control over software products. The Software Engineering Laboratory (SEL)-a joint venture between NASA's Goddard Space Flight Center, the University of Maryland, and Computer Sciences Corporation-started measurement of software development more than 15 years ago. Recently, the measurement of maintenance has been added to the scope of the SEL. In this article, the maintenance measurement program is presented as an addition to the already existing and well-established SEL development measurement program and evaluated in terms of its immediate benefits and long-term improvement potential. Immediate benefits of this program for the SEL include an increased understanding of the maintenance domain, the differences and commonalities between development and maintenance, and the cause-effect relationships between development and maintenance. Initial results from a sample maintenance study are presented to substantiate these benefits. The long-term potential of this program includes the use of maintenance baselines to better plan and manage future projects and to improve development and maintenance practices for future projects wherever warranted. C1 UNIV MARYLAND,DEPT COMP SCI,COLLEGE PK,MD 20742. UNIV MARYLAND,UMIACS,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 29 TC 11 Z9 11 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0164-1212 J9 J SYST SOFTWARE JI J. Syst. Softw. PD MAY PY 1992 VL 18 IS 2 BP 125 EP 138 DI 10.1016/0164-1212(92)90122-Z PG 14 WC Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA JB326 UT WOS:A1992JB32600003 ER PT J AU MYERS, MK HAUSMANN, JS AF MYERS, MK HAUSMANN, JS TI COMPUTATION OF ACOUSTIC SCATTERING FROM A MOVING RIGID SURFACE SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Article ID WAVE AB Application of the Kirchhoff formula for subsonically moving surfaces to scattering of sound from a moving rigid body is described. The formulation leads to a singular integral equation that yields surface values of the field. The integral equation is solved using a boundary element technique in conjunction with the Galerkin method. Several checks on the accuracy and validity of the scheme are discussed. Numerical results are obtained for scattering of sound from a harmonic point source co-moving with a thin, winglike body. RP MYERS, MK (reprint author), GEORGE WASHINGTON UNIV,NASA,LANGLEY RES CTR,JOINT INST ADVANCEMENT FLIGHT SCI,MAIL STOP 269,HAMPTON,VA 23665, USA. NR 13 TC 12 Z9 13 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD MAY PY 1992 VL 91 IS 5 BP 2594 EP 2605 DI 10.1121/1.402996 PG 12 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA HT688 UT WOS:A1992HT68800012 ER PT J AU HU, AD CUOMO, FW ZUCKERWAR, AJ AF HU, AD CUOMO, FW ZUCKERWAR, AJ TI THEORETICAL AND EXPERIMENTAL-STUDY OF A FIBER OPTIC MICROPHONE SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Article AB Modifications to condenser microphone theory yield new expressions for the membrane deflections at its center, which provide the basic theory for the fiber optic microphone. The theoretical analysis for the membrane amplitude and the phase response of the fiber optic microphone is given in detail in terms of its basic geometrical quantities. A relevant extension to the original concepts of the optical microphone includes the addition of a backplate with holes similar in design to present condenser microphone technology. This approach generates improved damping characteristics and extended frequency response that were not previously considered. The construction and testing of the improved optical fiber microphone provide experimental data that are in good agreement with the theoretical analysis. C1 UNIV RHODE ISL, DEPT PHYS, KINGSTON, RI 02881 USA. NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. NR 12 TC 22 Z9 23 U1 0 U2 1 PU ACOUSTICAL SOC AMER AMER INST PHYSICS PI MELVILLE PA STE 1 NO 1, 2 HUNTINGTON QUADRANGLE, MELVILLE, NY 11747-4502 USA SN 0001-4966 EI 1520-8524 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD MAY PY 1992 VL 91 IS 5 BP 3049 EP 3056 DI 10.1121/1.402940 PG 8 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA HT688 UT WOS:A1992HT68800059 ER PT J AU ROTH, DJ DEGUIRE, MR DOLHERT, LE AF ROTH, DJ DEGUIRE, MR DOLHERT, LE TI ULTRASONIC EVALUATION OF OXYGEN-CONTENT, MODULUS, AND MICROSTRUCTURE CHANGES IN YBA2CU3O7-X OCCURRING DURING OXIDATION AND REDUCTION SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article DE YTTRIUM BARIUM COPPER OXIDE; OXIDATION; REDUCTION; NONDESTRUCTIVE TESTING; MICROSTRUCTURE ID CU-O SYSTEM; SUPERCONDUCTORS; STOICHIOMETRY; DENSITY; PHASES AB Ultrasonic velocity measurements were used to evaluate the effects of oxidation and reduction on the oxygen content, elastic properties, and global microstructure of the YBa2Cu3O7-x ceramic superconductor for samples ranging from 70% to 90% of theoretical density. Bulk density, velocity, and Young's modulus generally increased with increasing oxygen content upon oxidation, and this behavior was reversible. Velocity image patterns obtained from ultrasonic scans were similar after oxidation and reduction treatments for a 90% dense sample, although the velocity value at any given point on the sample was changed following the treatments. The unchanging pattern correlated with destructive measurements showing that the spatial pore distribution (fraction and size) was not measurably altered after the treatments. Changes in superconducting behavior, crystal structure, and grain structure were observed consistent with changes in oxygen content. C1 CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106. WR GRACE & CO,DIV RES,COLUMBIA,MD 21044. RP ROTH, DJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 44 TC 1 Z9 1 U1 1 U2 1 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD MAY PY 1992 VL 75 IS 5 BP 1182 EP 1190 DI 10.1111/j.1151-2916.1992.tb05557.x PG 9 WC Materials Science, Ceramics SC Materials Science GA HU733 UT WOS:A1992HU73300022 ER PT J AU CHOU, MD AF CHOU, MD TI A SOLAR-RADIATION MODEL FOR USE IN CLIMATE STUDIES SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID WATER-VAPOR; ABSORPTION; PARAMETERIZATION; BANDS; CO2 AB A solar radiation routine has been developed for use in climate studies. It includes the absorption and scattering due to ozone, water vapor, oxygen, carbon dioxide, clouds, and aerosols. Rayleigh scattering is also included. The UV and visible region (lambda < 0.69-mu-m) is grouped into four bands. An effective coefficient for ozone absorption and an effective cross section for Rayleigh scattering are computed for each band. In the near-infrared region (lambda < 0.69-mu-m), the broadband parameterization is used to compute the absorption by water vapor in a clear atmosphere, and the k-distribution method is applied to compute fluxes in a scattering atmosphere. The reflectivity and transmissivity of a scattering layer are computed analytically using the delta-four-stream discrete-ordinate approximation. The two-stream adding method is then applied to compute fluxes for a composite of clear and scattering layers. Compared to the results of high spectral resolution and detailed multiple-scattering calculations, fluxes and heating rate are accurately computed to within a few percent. The high accuracy of flux and heating rate calculations is achieved with a reasonable amount of computing time. With the UV and visible region grouped into four bands, this solar radiation routine is useful not only for climate studies but also for studies on the photolysis in the upper atmosphere and the photosynthesis in the biosphere. RP CHOU, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CLIMATE & RADIAT BRANCH,CODE 913,GREENBELT,MD 20771, USA. NR 19 TC 173 Z9 176 U1 2 U2 12 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD MAY 1 PY 1992 VL 49 IS 9 BP 762 EP 772 DI 10.1175/1520-0469(1992)049<0762:ASRMFU>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HR508 UT WOS:A1992HR50800004 ER PT J AU MARDER, SR CHENG, LT TIEMANN, BG AF MARDER, SR CHENG, LT TIEMANN, BG TI THE 1ST MOLECULAR ELECTRONIC HYPERPOLARIZABILITIES OF HIGHLY POLARIZABLE ORGANIC-MOLECULES - 2,6-DI-TERT-BUTYLINDOANILINES SO JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS LA English DT Article ID OPTICAL NONLINEARITIES; DERIVATIVES AB The first molecular hyperpolarizabilities (beta) of a series of 2,6-di-tert-butylindoanilines, measured by electric-field-induced second harmonic generation, are somewhat more sensitive to donor strength than was found for analogously substituted nitrostilbenes, and dimethylindoaniline has a beta roughly twice that of its 2,6 di-tert-butylated analogue, measured in chloroform; solvatochromic measurements on the former compound suggest that this decrease in hyperpolarizability is consistent with a bound-solvent effect. C1 CALTECH,BECKMAN INST,CTR MOLEC MAT RESOURCE,PASADENA,CA 91125. DUPONT CO,CENT RES & DEV DEPT,WILMINGTON,DE 19880. RP MARDER, SR (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 13 TC 26 Z9 26 U1 0 U2 2 PU ROYAL SOC CHEMISTRY PI CAMBRIDGE PA THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON ROAD, CAMBRIDGE, CAMBS, ENGLAND CB4 4WF SN 0022-4936 J9 J CHEM SOC CHEM COMM JI J. Chem. Soc.-Chem. Commun. PD MAY 1 PY 1992 IS 9 BP 672 EP 674 DI 10.1039/c39920000672 PG 3 WC Chemistry, Multidisciplinary SC Chemistry GA HT216 UT WOS:A1992HT21600005 ER PT J AU HOVENAC, EA LOCK, JA AF HOVENAC, EA LOCK, JA TI ASSESSING THE CONTRIBUTIONS OF SURFACE-WAVES AND COMPLEX RAYS TO FAR-FIELD MIE SCATTERING BY USE OF THE DEBYE SERIES SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Article ID DIFFRACTION CATASTROPHE; RAINBOW; GLORY; DROPS AB The contributions of complex rays and the secondary radiation shed by surface waves to scattering by a dielectric sphere are calculated in the context of the Debye-series expansion of the Mie scattering amplitudes. Also, the contributions of geometrical rays are reviewed and compared with those of the Debye series. Interference effects among surface waves, complex rays, and geometrical rays are calculated, and the possibility of observing these interference effects is discussed. Experimental data supporting the observation of a surface-wave-geometrical-ray-interference pattern are presented. C1 CLEVELAND STATE UNIV,DEPT PHYS,CLEVELAND,OH 44115. RP HOVENAC, EA (reprint author), SVERDRUP TECHNOL INC,NASA,LEWIS RES CTR GRP,CLEVELAND,OH 44135, USA. NR 45 TC 98 Z9 104 U1 0 U2 6 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD MAY PY 1992 VL 9 IS 5 BP 781 EP 795 DI 10.1364/JOSAA.9.000781 PG 15 WC Optics SC Optics GA HQ478 UT WOS:A1992HQ47800016 ER PT J AU ESSICK, JM POOL, FS SHING, YH AF ESSICK, JM POOL, FS SHING, YH TI DEPOSITION TEMPERATURE-DEPENDENCE OF THE DEEP DEFECT DENSITY FOR A-SIH FILMS GROWN BY ELECTRON-CYCLOTRON RESONANCE MICROWAVE PLASMA SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article ID AMORPHOUS-SILICON FILMS; ENERGY; STREAM AB The dependence on deposition temperature of the mobility gap density of states has been determined for hydrogenated amorphous silicon (a-Si:H) films grown by electron cyclotron resonance (ECR) microwave plasma chemical vapor deposition (CVD). A minimum in the integrated deep defect density of 1 X 10(16) cm-3 Was found to occur at a temperature of approximately 250-degrees-C, while an Urbach slope minimum of 52 meV was observed at 175-degrees-C under our deposition conditions. Based on these measurements the ECR-grown films were found to be of excellent device quality and comparable to a-Si:H films grown by rf plasma-enhanced CVD. C1 JET PROP LAB,CTR SPACE MICROELECTR,PASADENA,CA 91109. RP ESSICK, JM (reprint author), OCCIDENTAL COLL,DEPT PHYS,LOS ANGELES,CA 90041, USA. NR 11 TC 2 Z9 2 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD MAY-JUN PY 1992 VL 10 IS 3 BP 521 EP 524 DI 10.1116/1.578182 PG 4 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA HU242 UT WOS:A1992HU24200017 ER PT J AU WANG, SDH ZHAN, BY AF WANG, SDH ZHAN, BY TI MARINE FISHERY RESOURCE-MANAGEMENT IN PEOPLES-REPUBLIC-OF-CHINA SO MARINE POLICY LA English DT Article AB This paper describes the PR Chinese marine fishery resources and China's management system. The marine fishery resources are described and resource utilization and associated problems are explained. The management system for marine fishery resources is analysed, including resource propagation and enhancement, mariculture regulations and marine environment protection. The administration and enforcement of the management system are then described. C1 SHANGHAI FISHERIES UNIV,SHANGHAI,PEOPLES R CHINA. RP WANG, SDH (reprint author), NATL MARINE FISHERIES SERV,1 BLACKBURN DR,GLOUCESTER,MA 01930, USA. NR 6 TC 2 Z9 3 U1 1 U2 2 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0308-597X J9 MAR POLICY JI Mar. Pol. PD MAY PY 1992 VL 16 IS 3 BP 197 EP 209 DI 10.1016/0308-597X(92)90081-Y PG 13 WC Environmental Studies; International Relations SC Environmental Sciences & Ecology; International Relations GA HV866 UT WOS:A1992HV86600004 ER PT J AU WHITTENBERGER, JD RAY, R JHA, SC AF WHITTENBERGER, JD RAY, R JHA, SC TI INFLUENCE OF GRAIN-SIZE ON THE CREEP-BEHAVIOR OF HFC-DISPERSED NIAL SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article ID PLASTIC-FLOW PROPERTIES; DIFFUSION; ALLOYS AB Rapid solidification technology has been utilized to produce a NiAl-4(wt.%)HfC composite containing about 0.3 vol.% HfC as dispersed 50 nm particles. Study of the 1300 K compressive creep properties demonstrated that the initial, small grain size microstructure was unstable under slow strain rate deformation conditions. The grain growth which occurred during testing led to considerable strengthening. Subsequent measurements of the creep properties of the coarse grained specimens revealed that this strength was achieved by a large increase in the activation energy for deformation without any change in the stress exponent. Based on this work it is concluded that large grain microstructures will be required for optimum elevated temperature creep properties in dispersed NiAl. C1 MARKO MAT INC,N BILLERICA,MA 01862. TEXAS INSTRUMENTS INC,ATTLEBORO,MA 02703. RP WHITTENBERGER, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 20 TC 15 Z9 15 U1 0 U2 0 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD MAY 1 PY 1992 VL 151 IS 2 BP 137 EP 146 PG 10 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA HW671 UT WOS:A1992HW67100003 ER PT J AU SUD, VK SRINIVASAN, RS CHARLES, JB BUNGO, MW AF SUD, VK SRINIVASAN, RS CHARLES, JB BUNGO, MW TI MATHEMATICAL-MODELING OF FLOW DISTRIBUTION IN THE HUMAN CARDIOVASCULAR-SYSTEM SO MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING LA English DT Article DE BLOOD FLOW DISTRIBUTION; MODELING OF CARDIOVASCULAR SYSTEM; SIMULATION AB The paper presents a detailed model of the entire human cardiovascular system which aims to study the changes in flow distribution caused by external stimuli, changes in internal parameters, or other factors. The arterial-venous network is represented by 325 interconnected elastic segments. The mathematical description of each segment is based on equations of hydrodynamics and those of stress/strain relationships in elastic materials. Appropriate input functions provide for the pumping of blood by the heart through the system. The analysis employs the finite-element technique which can accommodate any prescribed boundary conditions. Values of model parameters are from available data on physical and rheological properties of blood and blood vessels. As a representative example, simulation results on changes in flow distribution with changes In the elastic properties of blood vessels are discussed They indicate that the errors in the calculated overall flow rates are not significant even in the extreme case of arteries and veins behaving as rigid tubes. C1 KRUG INT,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP SUD, VK (reprint author), ALL INDIA INST MED SCI,DEPT BIOPHYS,NEW DELHI 110029,INDIA. NR 27 TC 4 Z9 4 U1 2 U2 2 PU PETER PEREGRINUS LTD PI HERTS PA SOUTHGATE HOUSE STEVENAGE PO BOX 8, HERTS, ENGLAND SG1 1HQ SN 0140-0118 J9 MED BIOL ENG COMPUT JI Med. Biol. Eng. Comput. PD MAY PY 1992 VL 30 IS 3 BP 311 EP 316 DI 10.1007/BF02446969 PG 6 WC Computer Science, Interdisciplinary Applications; Engineering, Biomedical; Mathematical & Computational Biology; Medical Informatics SC Computer Science; Engineering; Mathematical & Computational Biology; Medical Informatics GA JB823 UT WOS:A1992JB82300007 PM 1453803 ER PT J AU BOWMAN, RR NOEBE, RD RAJ, SV LOCCI, IE AF BOWMAN, RR NOEBE, RD RAJ, SV LOCCI, IE TI CORRELATION OF DEFORMATION MECHANISMS WITH THE TENSILE AND COMPRESSIVE BEHAVIOR OF NIAL AND NIAL(ZR) INTERMETALLIC ALLOYS SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID CYCLIC OXIDATION RESISTANCE; GRAIN-BOUNDARY DISLOCATIONS; AT-PERCENT ZIRCONIUM; PLASTIC-DEFORMATION; DUCTILE TRANSITION; BRITTLE-FRACTURE; SINGLE-CRYSTALS; TEMPERATURE; ALUMINIDES; CHEMISTRY AB To identify the mechanisms controlling strength and ductility in powder-extruded NiAl and NiAl + 0.05 at. pct Zr, tensile and compressive testing was performed from 300 to 1300 K for several grain sizes. Grain size refinement significantly increased yield stress in both alloys and, in some cases, slightly lowered the ductile-to-brittle transition temperature (DBTT), although no room-temperature tensile ductility was observed even in the finest grain size specimens. The small Zr addition increased the DBTT and changed the low-temperature fracture mode from intergranular in NiAl to a combination of intergranular and transgranular in the Zr-doped alloy. Scanning electron microscopy (SEM) of compression specimens deformed at room temperature revealed the presence of grain-boundary cracks in both alloys. These cracks were due to the incompatibility of strain in the polycrystalline material, owing to the lack of five independent slip systems. The tendency to form grain-boundary cracks, in addition to the low fracture stress of these alloys, contributed to the lack of tensile ductility at low temperatures. The operative slip system, both below and above the DBTT, was {110}[001] for both alloys. The change from brittle to ductile behavior with increasing temperatures was associated with the onset of diffusional processes. RP BOWMAN, RR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 59 TC 120 Z9 122 U1 0 U2 10 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD MAY PY 1992 VL 23 IS 5 BP 1493 EP 1508 DI 10.1007/BF02647332 PG 16 WC Materials Science, Multidisciplinary SC Materials Science GA HR599 UT WOS:A1992HR59900012 ER PT J AU HUANG, J AF HUANG, J TI A PARALLEL-SERIES-FED MICROSTRIP ARRAY WITH HIGH-EFFICIENCY AND LOW CROSS-POLARIZATION SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE ANTENNA; PARALLEL SERIES FEED; MICROSTRIP AB A linearly polarized traveling-wave microstrip array antenna is parallel and series fed by microstrip transmission lines. Excellent antenna efficiency is achieved by having proper impedance matching throughout the array and by properly utilizing the reflected power from the end of the array. Very low cross-polarization radiation is achieved by exciting the patches and transmission lines with anti-phase technique. RP HUANG, J (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 34 Z9 34 U1 0 U2 2 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD MAY PY 1992 VL 5 IS 5 BP 230 EP 233 DI 10.1002/mop.4650050509 PG 4 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA HL050 UT WOS:A1992HL05000008 ER PT J AU KINNE, S ACKERMAN, TP HEYMSFIELD, AJ VALERO, FPJ SASSEN, K SPINHIRNE, JD AF KINNE, S ACKERMAN, TP HEYMSFIELD, AJ VALERO, FPJ SASSEN, K SPINHIRNE, JD TI CIRRUS MICROPHYSICS AND RADIATIVE-TRANSFER - CLOUD FIELD-STUDY ON 28 OCTOBER 1986 SO MONTHLY WEATHER REVIEW LA English DT Article ID OPTICAL-PROPERTIES; ICE; SOLAR AB Cloud data acquired during the cirrus intensive field operation of FIRE 86 are analyzed for a 75 X 50-km2 cirrus cloud field that passed over Wausau, Wisconsin, during the morning of 28 October 1986. Remote-sensing measurements from the stratosphere and the ground detect an inhomogeneous cloud structure between 6 and 11 km in altitude. The measurements differentiate between an optically thicker (tau > 3) cirrus deck characterized by sheared precipitation trails and an optically thinner (tau < 2) cirrus cloud field in which individual cells of liquid water are imbedded. Simultaneous measurements of particle-size spectra and broadband radiative fluxes at multiple altitudes in the lower half of the cloud provide the basis for a comparison between measured and calculated fluxes. The calculated fluxes are derived from observations of cloud-particle-size distributions, cloud structure, and atmospheric conditions. Comparison of the modeled fluxes with the measurements shows that the model results underestimate the solar reflectivity and attenuation, as well as the downward infrared fluxes. Some of this discrepancy may be due to cloud inhomogeneities or to uncertainties in cloud microphysics, since there were no measurements of small ice crystals available. nor any microphysical measurements in the upper portion of the cirrus. Reconciling the model results with the measurements can be achieved either by adding large concentrations of small ice crystals or by altering the backscattering properties of the ice crystals. These results suggest that additional theoretical and experimental studies on small compact shapes, hollow ice crystals, and shapes with branches are needed. Also, new aircraft instrumentation is needed that can detect ice crystals with maximum dimensions between 5 and 50-mu-m. C1 PENN STATE UNIV,DEPT METEOROL,516 WALKER BLDG,UNIV PK,PA 16802. NASA,MOFFETT FIELD,CA 94035. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. UNIV UTAH,SALT LAKE CITY,UT 84112. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RI Heymsfield, Andrew/E-7340-2011 NR 19 TC 61 Z9 61 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD MAY PY 1992 VL 120 IS 5 BP 661 EP 684 DI 10.1175/1520-0493(1992)120<0661:CMARTC>2.0.CO;2 PG 24 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HR104 UT WOS:A1992HR10400001 ER PT J AU KEYSER, D SCHMIDT, BD DUFFY, DG AF KEYSER, D SCHMIDT, BD DUFFY, DG TI QUASI-GEOSTROPHIC DIAGNOSIS OF 3-DIMENSIONAL AGEOSTROPHIC CIRCULATIONS IN AN IDEALIZED BAROCLINIC DISTURBANCE SO MONTHLY WEATHER REVIEW LA English DT Article ID PRIMITIVE EQUATION MODEL; FEBRUARY 1979; FRONTOGENESIS; PREDICTION; STORM; WIND AB The kinematic technique of representing three-dimensional vertical circulations in baroclinic disturbances in terms of a vector streamfunction (referred to as the psi vector) recently proposed by the authors is placed in the context of quasigeostrophic (QG) theory. A diagnostic equation is derived for the psi vector from which the vertical velocity and the irrotational part of the ageostrophic velocity can be inferred. It is shown that, for domains that are periodic or unbounded horizontally, the psi vector is forced dynamically by the irrotational part of the Q vector. It is further shown for such domains that the vertical shear of the nondivergent part of the ageostrophic velocity is proportional to the nondivergent part of the Q vector. This, in principle, completes the diagnosis of the vertical velocity and the total ageostrophic velocity from the mass field, along with diabatic and frictional effects in the thermodynamic and momentum equations. It is demonstrated that the projection of the psi-vector equation onto the cross-front vertical plane leads to a generalization of the QG form of the Sawyer-Eliassen equation applicable to three-dimensional flows. The forcing of the scalar streamfunction for the transverse (cross-front) circulation comprises not only the confluence and horizontal shear terms from the two-dimensional case, but additional terms involving the component of the vertical velocity associated with the vertical circulation in the alongfront direction and the nondivergent component of the ageostrophic velocity in the cross-front plane. These additional terms vanish in the two-dimensional case, wherein the vertical circulation is confined to the cross-front plane and the nondivergent part of the ageostrophic velocity is restricted to the alongfront direction. The diagnostic methodologies for the total ageostrophic flow and for the generalized Sawyer-Eliassen equation are illustrated through applications to upper-level and surface frontal zones simulated in an f-plane primitive equation (PE) channel model of a finite-amplitude baroclinic wave. It is found that discrepancies in the sense of the cross-contour flow in jet-entrance and jet-exit regions between the QG-diagnosed ageostrophic flow and that simulated by the PE model can be traced to differences in the nondivergent part of the ageostrophic flow. Qualitative consistency is found, however, in the comparison between the QG irrotational ageostrophic flow and its PE counterpart, suggesting the utility of QG diagnoses of the vertical motion field in the vicinity of curved jet-front systems, where the geostrophic-momentum approximation may break down locally. In the generalized Sawyer-Eliassen equation, it is found that the confluence and horizontal shear forcing terms are dominant, but tend to be opposed by the term involving the component of the nondivergent part of the ageostrophic flow in the cross-front plane. The dominance of these "two-dimensional" forcing terms motivates a comparison between the diagnosed frontal circulations and those obtained in previous two-dimensional frontogenesis models. This comparison addresses the extent to which idealized frontogenetical mechanisms involving confluence and horizontal shear carry over to less restrictive, three-dimensional contexts. C1 WSI CORP,BILLERICA,MA. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP KEYSER, D (reprint author), SUNY ALBANY,DEPT ATMOSPHER SCI,ES 224,ALBANY,NY 12222, USA. NR 34 TC 20 Z9 20 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD MAY PY 1992 VL 120 IS 5 BP 698 EP 730 DI 10.1175/1520-0493(1992)120<0698:QDOTDA>2.0.CO;2 PG 33 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HR104 UT WOS:A1992HR10400003 ER PT J AU KEYSER, D SCHMIDT, BD DUFFY, DG AF KEYSER, D SCHMIDT, BD DUFFY, DG TI QUASI-GEOSTROPHIC VERTICAL MOTIONS DIAGNOSED FROM ALONG-ISENTROPE AND CROSS-ISENTROPE COMPONENTS OF THE Q VECTOR SO MONTHLY WEATHER REVIEW LA English DT Article AB In a recent paper on the kinematics of frontogenesis, Keyser et al. conjectured that partitioning the Q vector into along- and cross-isentrope components yields vertical-motion patterns that are respectively cellular and banded-the former on the scale of the baroclinic disturbance and the latter on the scale of the embedded frontal zones. This conjecture is examined diagnostically through solution of the quasigeostrophic omega equation, using the output from a nearly adiabatic and frictionless f-plane primitive equation channel model of the evolution of a baroclinic disturbance to finite amplitude. The results of the present study support the proposed conjecture, suggesting the following interpretation of the characteristic comma structure of the vertical-motion field in midlatitude baroclinic disturbances: The comma shape arises from the modification or distortion of a wave-scale dipole pattern by frontal-scale asymmetries. The dipole is associated with the along-isentrope component of the Q vector, reflecting the wavelike pattern in the potential temperature field within the baroclinic disturbance; the asymmetries are associated with the cross-isentrope component of the Q vector, reflecting the presence of frontal zones within the baroclinic disturbance. C1 WSI CORP,BILLERICA,MA. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP KEYSER, D (reprint author), SUNY ALBANY,DEPT ATMOSPHER SCI,ES 224,ALBANY,NY 12222, USA. NR 12 TC 42 Z9 44 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD MAY PY 1992 VL 120 IS 5 BP 731 EP 741 DI 10.1175/1520-0493(1992)120<0731:QVMDFA>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HR104 UT WOS:A1992HR10400004 ER PT J AU ALTERGARTENBERG, R FALES, CL HUCK, FO RAHMAN, ZU REICHENBACH, SE AF ALTERGARTENBERG, R FALES, CL HUCK, FO RAHMAN, ZU REICHENBACH, SE TI MULTIRESPONSE IMAGING - INFORMATION AND FIDELITY SO MULTIDIMENSIONAL SYSTEMS AND SIGNAL PROCESSING LA English DT Article DE MULTIRESPONSE IMAGING; SUB-SAMPLE RESOLUTION; RESTORATION; FIDELITY; INFORMATION THEORY ID RESTORATION; IMAGES AB Multiresponse imaging is a process that acquires A images, each with a different optical response, and reassembles them into a single image with an improved resolution that can approach 1 square-root A times the photodetector-array sampling lattice. Our goals are to optimize the performance of this process in terms of the resolution and fidelity of the restored image and to assess the amount of information required to do so. The theoretical approach is based on the extension of both image restoration and rate distortion theories from their traditional realm of signal processing to image processing which includes image gathering and display. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. SCI & TECHNOL CORP,HAMPTON,VA 23666. UNIV NEBRASKA,DEPT COMP SCI & ENGN,LINCOLN,NE 68588. RP ALTERGARTENBERG, R (reprint author), OLD DOMINION UNIV,DEPT MATH,NORFOLK,VA 23529, USA. NR 21 TC 4 Z9 4 U1 0 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0923-6082 J9 MULTIDIM SYST SIGN P JI Multidimens. Syst. Signal Process. PD MAY PY 1992 VL 3 IS 2-3 BP 189 EP 210 DI 10.1007/BF01942042 PG 22 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA HT311 UT WOS:A1992HT31100006 ER PT J AU CHEN, RT ROBINSON, D LU, H WANG, MR JANNSON, T BAUMBICK, R AF CHEN, RT ROBINSON, D LU, H WANG, MR JANNSON, T BAUMBICK, R TI RECONFIGURABLE OPTICAL INTERCONNECTION NETWORK FOR MULTIMODE OPTICAL FIBER SENSOR ARRAYS SO OPTICAL ENGINEERING LA English DT Article DE OPTICAL INTERCONNECTIONS; MULTIMODE FIBER SENSOR ARRAYS ID WAVEGUIDE CUTOFF MODULATOR; SWITCH AB A single-source, single-detector architecture has been developed to implement a reconfigurable optical interconnection network for multimode optical fiber sensor arrays. The network was realized by integrating LiNbO3 electro-optic (EO) gratings working at the Raman Nath regime and a massive fan-out waveguide hologram (WH) working at the Bragg regime onto a multimode glass waveguide. The glass waveguide utilized the whole substrate as a guiding medium. A 1-to-59 massive waveguide fan-out was demonstrated using a WH operating at 514 nm. Measured diffraction efficiency of 59% was experimentally confirmed. Reconfigurability of the interconnection was carried out by generating an EO grating through an externally applied electric field. Unlike conventional single-mode integrated optical devices, the guided mods demonstrated here has an azimuthal symmetry in mode profile which is the same as that of a fiber mode. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHEN, RT (reprint author), PHYS OPT CORP,2545 W 237TH ST,SUITE B,TORRANCE,CA 90505, USA. NR 27 TC 11 Z9 11 U1 1 U2 5 PU SOC PHOTO-OPT INSTRUM ENG PI BELLINGHAM PA PO BOX 10, BELLINGHAM, WA 98227-0010 SN 0091-3286 J9 OPT ENG JI Opt. Eng. PD MAY PY 1992 VL 31 IS 5 BP 1098 EP 1106 DI 10.1117/12.56154 PG 9 WC Optics SC Optics GA HU370 UT WOS:A1992HU37000030 ER PT J AU NORTHROP, TG AF NORTHROP, TG TI DUSTY PLASMAS SO PHYSICA SCRIPTA LA English DT Article; Proceedings Paper CT SPECIAL SESSION OF THE SPRING COLLEGE ON PLASMA PHYSICS : DUSTY PLASMAS CY JUN 14-21, 1991 CL TRIESTE, ITALY SP INT CTR THEORET PHYS, EUROPEAN ECON COMMUNITY ID CHARGED DUST; PLANETARY MAGNETOSPHERES; ROTATING MAGNETOSPHERES; SATURNS RINGS; PARTICLES; GRAINS; SYSTEM; MOTION; SPACE; MODEL AB Dust grains immersed in plasma become charged. The charge is determined by the plasma characteristics, by secondary and photoemission from the grain, by grain velocity, and at any given instant by the past time history of the charging currents. This charge affects the Coulomb drag on a grain moving through the plasma. It affects the motion of the grain in an electromagnetic field of a planetary magnetosphere, and it is involved in the formation of the spokes in Saturn's rings and in the erosion of the rings by micrometeorites. And finally it affects the coagulation rate of dust into larger bodies. RP NORTHROP, TG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 38 TC 281 Z9 284 U1 3 U2 12 PU ROYAL SWEDISH ACAD SCIENCES PI STOCKHOLM PA PUBL DEPT BOX 50005, S-104 05 STOCKHOLM, SWEDEN SN 0281-1847 J9 PHYS SCRIPTA JI Phys. Scr. PD MAY PY 1992 VL 45 IS 5 BP 475 EP 490 DI 10.1088/0031-8949/45/5/011 PG 16 WC Physics, Multidisciplinary SC Physics GA HW111 UT WOS:A1992HW11100012 ER PT J AU HO, YK BHATIA, AK AF HO, YK BHATIA, AK TI DOUBLY EXCITED (3)P(E) RESONANT STATES IN PS- SO PHYSICAL REVIEW A LA English DT Article ID POSITRONIUM NEGATIVE-ION AB Doubly excited P-3(e) resonant states in Ps- are calculated using a method of complex-coordinate rotation. Resonance parameters (both resonance positions and widths) for doubly excited states associated with the n = 2, 3, 4, 5, and 6 thresholds of positronium atoms are evaluated using elaborate Hylleraas-type functions. In addition to ten Feshbach-type resonances lying below various Ps thresholds, we have identified three shape resonances, one each lying above the n = 2, 4, and 6 Ps thresholds. It is further noted that the energy levels for the present P-3(e) states are nearly degenerate with respect to the previously calculated P-1(o) states. Such a symmetric character suggests that the highly and doubly excited Ps-, similar to its counterpart in H-, would exhibit rovibrational behaviors analogous to those of XYX triatomic molecules. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HO, YK (reprint author), LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803, USA. RI Ho, Yew Kam/F-7912-2012 NR 16 TC 32 Z9 32 U1 0 U2 1 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 MAY 1 PY 1992 VL 45 IS 9 BP 6268 EP 6271 DI 10.1103/PhysRevA.45.6268 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA HT733 UT WOS:A1992HT73300019 ER PT J AU SUD, VK SRINIVASAN, RS CHARLES, JB BUNGO, MW AF SUD, VK SRINIVASAN, RS CHARLES, JB BUNGO, MW TI THE EFFECTS OF EXERCISE ON BLOOD-FLOW WITH REFERENCE TO THE HUMAN CARDIOVASCULAR-SYSTEM - A FINITE-ELEMENT STUDY SO PHYSICS IN MEDICINE AND BIOLOGY LA English DT Article AB This paper reports on a theoretical investigation into the effects of vasomotion on blood through the human cardiovascular system. The finite element method has been used to analyse the model. Vasoconstriction and vasodilation may be effected either through the action of the central nervous system or autoregulation. One of the conditions responsible for vasomotion is exercise. The proposed model has been solved and quantitative results of flows and pressures due to changing the conductances of specific networks of arterioles, capillaries and venules comprising the arms, legs, stomach and their combinations have been obtained. C1 KRUG INT,HOUSTON,TX. NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. RP SUD, VK (reprint author), ALL INDIA INST MED SCI,DEPT BIOPHYS,NEW DELHI 110016,INDIA. NR 24 TC 1 Z9 1 U1 1 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0031-9155 J9 PHYS MED BIOL JI Phys. Med. Biol. PD MAY PY 1992 VL 37 IS 5 BP 1033 EP 1045 DI 10.1088/0031-9155/37/5/001 PG 13 WC Engineering, Biomedical; Radiology, Nuclear Medicine & Medical Imaging SC Engineering; Radiology, Nuclear Medicine & Medical Imaging GA HU206 UT WOS:A1992HU20600001 PM 1608993 ER PT J AU KAMOTANI, Y LEE, JH OSTRACH, S PLINE, A AF KAMOTANI, Y LEE, JH OSTRACH, S PLINE, A TI AN EXPERIMENTAL-STUDY OF OSCILLATORY THERMOCAPILLARY CONVECTION IN CYLINDRICAL CONTAINERS SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID FLOATING-ZONE; MARANGONI-CONVECTION; REDUCED GRAVITY; FLOWS; LIQUID; SURFACE; STEADY; ONSET AB An experimental study of oscillatory thermocapillary convection in small cylindrical containers with a heating wire placed along the center axis is performed by investigating the flow structures and temperature distributions under various conditions. To supplement the flow visualization the surface is scanned using an infrared imager. Here 2 cS viscosity (Pr = 27) silicone oil is used as the test fluid. It is observed that beyond a certain temperature difference between the container wall and the heating wire, a distinctive unsteady flow pattern appears. This unsteady phenomenon is identified as oscillatory thermocapillary. After the onset of oscillations the flow structure becomes nonaxisymmetric and wave motion is observed at the free surface. It is shown that the critical temperature difference is independent of container dimensions if the aspect ratio is fixed. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP KAMOTANI, Y (reprint author), CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106, USA. NR 27 TC 31 Z9 31 U1 1 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD MAY PY 1992 VL 4 IS 5 BP 955 EP 962 DI 10.1063/1.858276 PG 8 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA HQ719 UT WOS:A1992HQ71900013 ER PT J AU MACARAEG, MG DAUDPOTA, QI AF MACARAEG, MG DAUDPOTA, QI TI NUMERICAL-STUDIES OF TRANSVERSE CURVATURE EFFECTS ON TRANSONIC FLOW STABILITY SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article AB A numerical study of transverse curvature effects on compressible flow temporal stability for transonic to low supersonic Mach numbers is presented for axisymmetric modes. The mean flows studied include a similar boundary-layer profile and a nonsimilar axisymmetric boundary-layer solution. The effect of neglecting curvature in the mean flow produces only small quantitative changes in the disturbance growth rate. For transonic Mach numbers (1-1.4) and aerodynamically relevant Reynolds numbers (5000-10000 based on displacement thickness), the maximum growth rate is found to increase with curvature-the maximum occurring at a nondimensional radius (based on displacement thickness) between 30 and 100. C1 OLD DOMINION UNIV,RES FDN,NORFOLK,VA 23529. RP MACARAEG, MG (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 19 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD MAY PY 1992 VL 4 IS 5 BP 975 EP 983 DI 10.1063/1.858224 PG 9 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA HQ719 UT WOS:A1992HQ71900015 ER PT J AU BONAVITO, NL DRESSLER, RF GARFINKLE, B HOLLISTER, WM JANICZEK, PM AF BONAVITO, NL DRESSLER, RF GARFINKLE, B HOLLISTER, WM JANICZEK, PM TI VINTI,JOHN,P. - OBITUARY SO PHYSICS TODAY LA English DT Item About an Individual C1 USN OBSERV,WASHINGTON,DC 20390. YALE UNIV,NEW HAVEN,CT 06520. MIT,CAMBRIDGE,MA 02139. RP BONAVITO, NL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD MAY PY 1992 VL 45 IS 5 BP 77 EP 78 DI 10.1063/1.2809675 PG 2 WC Physics, Multidisciplinary SC Physics GA HT547 UT WOS:A1992HT54700017 ER PT J AU GERMOND, AJ NIEBUR, D AF GERMOND, AJ NIEBUR, D TI SURVEY OF KNOWLEDGE-BASED SYSTEMS IN POWER-SYSTEMS - EUROPE SO PROCEEDINGS OF THE IEEE LA English DT Article AB This paper presents a survey of the development and experience with knowledge-based systems applied to power systems in Europe, including expert systems used in operation. In Sections I-III of the paper, the technical aspects of power system operation are briefly reviewed, the role of computers in power systems is discussed, and the motivation for investigating knowledge-based applications in this context is identified. In Sections IV and V, the structure of the research and industrial organizations involved in the development and implementation is described and the characteristics of main application areas are discussed. Based on an enquiry conducted in Europe in 1991 a survey of expert systems under development or in practical use is given. Finally the experience gained with the application of knowledge-based systems in power systems, and its impact on future expert system development and implementation is discussed in Sections VI-VIII. C1 JET PROP LAB,PASADENA,CA 91109. RP GERMOND, AJ (reprint author), ECOLE POLYTECH FED LAUSANNE,RES ENERGIE ELECTR LAB,CH-1015 LAUSANNE,SWITZERLAND. NR 61 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 SN 0018-9219 J9 P IEEE JI Proc. IEEE PD MAY PY 1992 VL 80 IS 5 BP 732 EP 744 DI 10.1109/5.137228 PG 13 WC Engineering, Electrical & Electronic SC Engineering GA HV746 UT WOS:A1992HV74600009 ER PT J AU FEIBELMAN, WA ALLER, LH HYUNG, S AF FEIBELMAN, WA ALLER, LH HYUNG, S TI VARIABILITY OF EMISSION-LINES IN THE PLANETARY-NEBULAE IC-4997 AND NGC-6572 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID SPECTRA AB We compare new IUE high-dispersion data and recent ground-based spectra of the planetary nebulae IC 4997 and NGC 6572 with equivalent IUE observations taken in 1980 and optical data taken in 1974-1990. Significant changes are detected in many emission-line fluxes in IC 4997, and primarily in He II and C IV for NGC 6572. We interpret these changes as due to recent temperature increases in the central stars of the planetaries which are known to belong to a small set which have shown variability in the past. C1 UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. RP FEIBELMAN, WA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6841,GREENBELT,MD 20771, USA. NR 23 TC 25 Z9 25 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD MAY PY 1992 VL 104 IS 675 BP 339 EP 349 DI 10.1086/133003 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HU953 UT WOS:A1992HU95300007 ER PT J AU MADORE, BF FREEDMAN, WL AF MADORE, BF FREEDMAN, WL TI THE REDDENING TO THE GALAXY IC-342 FROM CCD BV PHOTOMETRY OF ITS BRIGHTEST STARS SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID EXTINCTION AB The intrinsic luminosity and distance to the low-galactic-latitude galaxy IC 342 have been a matter of some debate, largely due to the uncertainty in the estimates for the extinction. The dynamical influence of IC 342 on the Local Group may be more significant than has commonly been believed if a high reddening value and a low distance modulus to this galaxy is confirmed. In an effort to estimate the reddening independently for this galaxy, we have obtained CCD BV photometry for 117 stars brighter than V = 22.0 mag in a field centered near a spiral arm in IC 342. The plume of main sequence and slightly evolved blue supergiant stars is detected at V = 19.4 mag. However, the plume is centered at a color of (B-V) = 0.54 mag. A comparison with similar color-magnitude-diagram data for the brightest stars in IC 1613 suggests that these stars in IC 342 are reddened by E(B-V) = 0.79 +/- 0.05 mag (A(B) = 3.32 +/- 0.21 mag). This value is in good agreement with the similarly high values suggested by the Burstein-Heiles conversions of Galactic H I column density to color excess, and especially by the recent measurement of the Balmer decrement of H II regions by McCall. C1 CARNEGIE INST WASHINGTON,OBSERV,PASADENA,CA 91101. CANADA FRANCE HAWAII TELESCOPE CORP,KAMUELA,HI. RP MADORE, BF (reprint author), CALTECH,CTR INFRARED ANAL & PROC,NASA,IPAC EXTRAGALACT DATABASE,MC 100-22,PASADENA,CA 91125, USA. NR 14 TC 20 Z9 20 U1 0 U2 0 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD MAY PY 1992 VL 104 IS 675 BP 362 EP 366 DI 10.1086/133005 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HU953 UT WOS:A1992HU95300009 ER PT J AU GILLILAND, RL MORRIS, SL WEYMANN, RJ EBBETS, DC LINDLER, DJ AF GILLILAND, RL MORRIS, SL WEYMANN, RJ EBBETS, DC LINDLER, DJ TI RESOLUTION AND NOISE PROPERTIES OF THE GODDARD HIGH-RESOLUTION SPECTROGRAPH SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article AB The Goddard High-Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST) provides an unprecedented capability for ultraviolet spectroscopy of a wide range of astronomical targets. The combination of high resolution (to R is similar to 100,000), good sensitivity (maximum total system quantum efficiency of approximately 1%), low background noise (order 0.01 counts s-1 diode-1), coupled with the fast photon-counting detector system makes the GHRS a very flexible instrument. Unfortunately, the presence of spherical aberration in the primary mirror of HST complicates issues of both observing strategy and data analysis procedures, since the throughput and resolving-power losses of the two available GHRS apertures are often offsetting. We discuss several characteristics of GHRS observations, and data-analysis procedures, including deconvolution, with a particular emphasis on the detection of weak absorption lines in low-signal-to-noise observations. We find that observations with the GHRS large aperture generally provide greater sensitivity for the detection of weak, isolated spectral features than does use of the small aperture for equal observing times. At low signal-to-noise levels a Poisson distribution well represents the noise characteristics. Analysis of the UV spectrum of 3C 273 serves as the motivation for this study. Deconvolution of small-aperture first-order grating spectra taken at high signal to noise may be preferred to less efficient echelle spectra in some cases. We argue that GHRS observations should be routinely structured with use of comb-addition, quarter-substepping, FP-SPLITS, and multiple repeats to allow proper discrimination against noise events that may mimic spectral features. C1 OBSERV CARNEGIE INST WASHINGTON,PASADENA,CA 91101. BALL AEROSP CORP,BALL AEROSP SYST GRP,GHRS PROJECT JWF3,BOULDER,CO 80306. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP GILLILAND, RL (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. RI Morris, Simon/G-7981-2011 OI Morris, Simon/0000-0003-4866-110X NR 18 TC 28 Z9 28 U1 0 U2 1 PU ASTRONOMICAL SOC PACIFIC PI SAN FRANCISCO PA 390 ASHTON AVE, SAN FRANCISCO, CA 94112 SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD MAY PY 1992 VL 104 IS 675 BP 367 EP 382 DI 10.1086/133006 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HU953 UT WOS:A1992HU95300010 ER PT J AU SINGER, MJ FINE, P VEROSUB, KL CHADWICK, OA AF SINGER, MJ FINE, P VEROSUB, KL CHADWICK, OA TI TIME-DEPENDENCE OF MAGNETIC-SUSCEPTIBILITY OF SOIL CHRONOSEQUENCES ON THE CALIFORNIA COAST SO QUATERNARY RESEARCH LA English DT Article ID NORTHERN CALIFORNIA C1 UNIV CALIF DAVIS,DEPT GEOL,DAVIS,CA 95616. VOLCANI CTR,INST SOILS & WATER,BET DAGAN,ISRAEL. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP SINGER, MJ (reprint author), UNIV CALIF DAVIS,DEPT LAND AIR & WATER RESOURCES,DAVIS,CA 95616, USA. NR 14 TC 64 Z9 67 U1 0 U2 4 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0033-5894 J9 QUATERNARY RES JI Quat. Res. PD MAY PY 1992 VL 37 IS 3 BP 323 EP 332 DI 10.1016/0033-5894(92)90070-Y PG 10 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA HQ732 UT WOS:A1992HQ73200005 ER PT J AU COURTIN, R MCKAY, CP POLLACK, J AF COURTIN, R MCKAY, CP POLLACK, J TI THE GREENHOUSE-EFFECT WITHIN THE SOLAR-SYSTEM SO RECHERCHE LA French DT Article ID EARTH; ATMOSPHERES; EVOLUTION; VENUS C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP COURTIN, R (reprint author), OBSERV PARIS,DEPT RECH SPATIALE,CNRS,F-92190 MEUDON,FRANCE. NR 17 TC 1 Z9 1 U1 0 U2 1 PU SOC ED SCIENTIFIQUES PI PARIS 06 PA 57 RUE DE SEINE, 75280 PARIS 06, FRANCE SN 0029-5671 J9 RECHERCHE JI Recherche PD MAY PY 1992 VL 23 IS 243 BP 542 EP 549 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HU961 UT WOS:A1992HU96100005 ER PT J AU HARDING, LW ITSWEIRE, EC ESAIAS, WE AF HARDING, LW ITSWEIRE, EC ESAIAS, WE TI DETERMINATION OF PHYTOPLANKTON CHLOROPHYLL CONCENTRATIONS IN THE CHESAPEAKE BAY WITH AIRCRAFT REMOTE-SENSING SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID OCEAN COLOR; ESTUARIES; PATTERNS; NUTRIENT; DYNAMICS; DELAWARE; PIGMENTS; SHIP AB This article describes remote sensing measurements of the distribution of phytoplankton chlorophyll concentrations in the Chesapeake Bay during 1989. The goal of this study was to show that remote sensing from light aircraft can complement and extend measurements made from traditional platforms and provide data of improved temporal and spatial resolution, leading to a better understanding of phytoplankton dynamics in the estuary. We followed the developments of the winter-spring diatom bloom in the polyhaline to mesohaline regions of the estuary and of the late-spring and summer dinoflagellate blooms in oligohaline and mesohaline regions. The instrument we used is an aircraft-borne, visible band radiometer system, NASA's Ocean Data Acquisition System (ODAS). The ODAS instrument package has three radiometers in the blue to blue-green part of the visible spectrum (460 nm, 490 nm, and 520 nm), an infrared temperature sensor, a broad-band (400-700 nm) downwelling irradiance sensor, Loran-C navigation, and a PC for data acquisition. During 1989, 14 flights were conducted in a 19-week period. Two additional missions were flown in conjunction with local shipboard operations for obtaining concurrent radiance measurements and in situ chlorophyll data. The main sources of in situ data used in algorithm development were semi-monthly to monthly cruises conducted by the Mainstem Water Quality Monitoring Program of the states of Maryland and Virginia as part of the Chesapeake Bay Program's (CBP) activities. Data for algorithm development were also obtained from shipboard measurements made in an experiment with ODAS and NASA's Airborne Oceanographic Lidar (AOL) to study the suitability of various waveband combinations for recovering chlorophyll concentrations. This article presents the local chlorophyll algorithm we developed using ODAS data and in situ chlorophyll data, interpolated maps of chlorophyll concentration generated by applying the algorithm to aircraft radiance data, ancillary in situ data on nutrients, turbidity, streamflow, and light availability, and an interpretation of phytoplankton dynamics in terms of the chlorophyll distribution in the Chesapeake Bay during 1989. C1 JOHNS HOPKINS UNIV,DEPT GEOG & ENVIRONM ENGN,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,GREENBELT,MD 20771. RP HARDING, LW (reprint author), UNIV MARYLAND,SEA GRANT COLL,1123 TALIAFERRO HALL,COLLEGE PK,MD 20742, USA. NR 32 TC 28 Z9 28 U1 0 U2 1 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD MAY PY 1992 VL 40 IS 2 BP 79 EP 100 DI 10.1016/0034-4257(92)90007-7 PG 22 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA HR396 UT WOS:A1992HR39600001 ER PT J AU MAY, RD AF MAY, RD TI CORRELATION-BASED TECHNIQUE FOR AUTOMATED TUNABLE DIODE-LASER SCAN STABILIZATION SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID SPECTROMETER; NO2; STRATOSPHERE AB A software-based method for real-time, active stabilization of tunable diode laser spectral scans is described. The procedure is suitable for use with field and laboratory instrumentation where automated, unattended spectrometer operation is required. An autocorrelation of two high-resolution reference gas infrared spectra is computed at regular intervals, and the location of the maximum value of the autocorrelation provides the relative abscissa shift between the spectra. Small adjustments to the laser scan parameters are thereby made to ensure that drifts in the laser output frequency are tracked and compensated. Calculations required for stabilization of a 512-point spectrum can be completed in under 25 ms using an inexpensive, moderate-speed, array processor installed in a PC. RP MAY, RD (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 5 Z9 5 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAY PY 1992 VL 63 IS 5 BP 2922 EP 2926 DI 10.1063/1.1142587 PG 5 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA HR942 UT WOS:A1992HR94200002 ER PT J AU ROACH, PR AF ROACH, PR TI KEVLAR SUPPORT FOR THERMAL ISOLATION AT LOW-TEMPERATURES SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Note AB A cryogenic support has been developed that rigidly attaches two U-shaped aluminum beams to each other with strands of Kevlar. The Kevlar creates a very strong and stiff coupling between the beams while allowing only a very small heat to flow between them. Measurements at room temperature and at 77 K confirm the stiffness and strength of the support. RP ROACH, PR (reprint author), NASA,AMES RES CTR,DIV SPACE PROJECTS,MOFFETT FIELD,CA 94035, USA. NR 2 TC 12 Z9 12 U1 1 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAY PY 1992 VL 63 IS 5 BP 3216 EP 3217 DI 10.1063/1.1142582 PG 2 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA HR942 UT WOS:A1992HR94200053 ER PT J AU CHARLSON, RJ SCHWARTZ, SE HALES, JM CESS, RD COAKLEY, JA HANSEN, JE HOFMANN, DJ AF CHARLSON, RJ SCHWARTZ, SE HALES, JM CESS, RD COAKLEY, JA HANSEN, JE HOFMANN, DJ TI AEROSOLS AND GLOBAL WARMING - RESPONSE SO SCIENCE LA English DT Letter C1 UNIV WASHINGTON, INST ENVIRONM STUDIES, SEATTLE, WA 98195 USA. BROOKHAVEN NATL LAB, DIV ENVIRONM CHEM, UPTON, NY 11973 USA. PACIFIC NW LAB, DEPT ATMOSPHER SCI, RICHLAND, WA 99352 USA. SUNY STONY BROOK, INST TERR & PLANETARY ATMOSPHERES, STONY BROOK, NY 11794 USA. OREGON STATE UNIV, DEPT ATMOSPHER SCI, CORVALLIS, OR 97331 USA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. RP CHARLSON, RJ (reprint author), UNIV WASHINGTON, DEPT ATMOSPHER SCI, SEATTLE, WA 98195 USA. RI Schwartz, Stephen/C-2729-2008 OI Schwartz, Stephen/0000-0001-6288-310X NR 6 TC 12 Z9 12 U1 3 U2 8 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 1 PY 1992 VL 256 IS 5057 BP 598 EP 599 DI 10.1126/science.256.5057.598-a PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HR185 UT WOS:A1992HR18500003 PM 17843469 ER PT J AU SMITH, MD GIERASCH, PJ SCHINDER, PJ AF SMITH, MD GIERASCH, PJ SCHINDER, PJ TI A GLOBAL TRAVELING-WAVE ON VENUS SO SCIENCE LA English DT Article ID CLOUD PATTERNS; ATMOSPHERE; TIME AB The dominant large-scale pattern in the clouds of Venus has been described as a "Y" or "PSI" and tentatively identified by earlier workers as a Kelvin wave. A detailed calculation of linear wave modes in the Venus atmosphere verifies this identification. Cloud feedback by infrared heating fluctuations is a plausible excitation mechanism. Modulation of the large-scale pattern by the wave is a possible explanation for the Y. Momentum transfer by the wave could contribute to sustaining the general circulation. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP SMITH, MD (reprint author), CORNELL UNIV,DEPT ASTRON,SPACE SCI BLDG,ITHACA,NY 14853, USA. RI Smith, Michael/C-8875-2012 NR 24 TC 16 Z9 16 U1 0 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAY 1 PY 1992 VL 256 IS 5057 BP 652 EP 655 DI 10.1126/science.256.5057.652 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HR185 UT WOS:A1992HR18500028 PM 17843488 ER PT J AU SMITH, PP OLIVER, BF NOEBE, RD AF SMITH, PP OLIVER, BF NOEBE, RD TI SOLIDIFICATION PROCESSING OF INTERMETALLIC NB-AL ALLOYS SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP SMITH, PP (reprint author), UNIV TENNESSEE,KNOXVILLE,TN 37996, USA. NR 7 TC 7 Z9 7 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD MAY 1 PY 1992 VL 26 IS 9 BP 1365 EP 1370 DI 10.1016/0956-716X(92)90650-4 PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA HP023 UT WOS:A1992HP02300011 ER PT J AU ZINGG, DW YARROW, M AF ZINGG, DW YARROW, M TI A METHOD OF SMOOTH BIVARIATE INTERPOLATION FOR DATA GIVEN ON A GENERALIZED CURVILINEAR GRID SO SIAM JOURNAL ON SCIENTIFIC AND STATISTICAL COMPUTING LA English DT Article DE INTERPOLATION; GENERALIZED CURVILINEAR COORDINATES AB A method of locally bicubic interpolation is presented for data given at the nodes of a two-dimensional generalized curvilinear grid. The physical domain is transformed to a computational domain in which the grid is uniform and rectangular by a generalized curvilinear coordinate transformation. The metrics of the transformation are obtained by finite differences in the computational domain. Metric derivatives are determined by repeated application of the chain rule for partial differentiation. Given the metrics and the metric derivatives, the partial derivatives required to determine a locally bicubic interpolant can be estimated at each data point using finite differences in the computational domain. A bilinear transformation is used to analytically transform the individual quadrilateral cells in the physical domain into unit squares, thus allowing the use of simple formulas for bicubic interpolation. C1 STERLING SOFTWARE,NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP ZINGG, DW (reprint author), UNIV TORONTO,INST AEROSP STUDIES,TORONTO M3H 5T6,ONTARIO,CANADA. NR 8 TC 2 Z9 2 U1 0 U2 1 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER, PHILADELPHIA, PA 19104-2688 SN 0196-5204 J9 SIAM J SCI STAT COMP PD MAY PY 1992 VL 13 IS 3 BP 687 EP 693 DI 10.1137/0913040 PG 7 WC Mathematics, Applied SC Mathematics GA HP918 UT WOS:A1992HP91800004 ER PT J AU SHELTON, RO PETERSON, JK AF SHELTON, RO PETERSON, JK TI CONTROLLING A TRUCK WITH AN ADAPTIVE CRITIC CMAC DESIGN SO SIMULATION LA English DT Article DE ARTIFICIAL NEURAL NETWORKS; NEUROCONTROL; CMAC ARCHITECTURES; ADAPTIVE CRITIC ID SENSOR-BASED CONTROL AB In this study, CMAC (Cerebellar Model Articulated Controller) neural architectures are shown to be viable for the purposes of real-time learning and control. An adaptive critic neuro-control design has been implemented that learns in real-time how to back up a trailer truck along a fixed straight line trajectory. The truck backer-uppper experiment is a standard performance measure in the neural network literature, but previously the training of the controllers was done off-line. With the CMAC neural architectures, it was possible to train the neuro-controllers on-line in real-time on a MS-DOS PC 386. C1 CLEMSON UNIV,DEPT MATH SCI,CLEMSON,SC 29634. RP SHELTON, RO (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SOFTWARE TECHNOL BRANCH,DIV INFORMAT TECHNOL,HOUSTON,TX 77058, USA. NR 10 TC 17 Z9 17 U1 2 U2 2 PU SIMULATION COUNCILS INC PI SAN DIEGO PA PO BOX 17900, SAN DIEGO, CA 92117 SN 0037-5497 J9 SIMULATION JI Simulation PD MAY PY 1992 VL 58 IS 5 BP 319 EP 326 DI 10.1177/003754979205800504 PG 8 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering SC Computer Science GA HX900 UT WOS:A1992HX90000005 ER PT J AU BROWN, TX TRAN, MD DUONG, T DAUD, T THAKOOR, AP AF BROWN, TX TRAN, MD DUONG, T DAUD, T THAKOOR, AP TI CASCADED VLSI NEURAL NETWORK CHIPS - HARDWARE LEARNING FOR PATTERN-RECOGNITION AND CLASSIFICATION SO SIMULATION LA English DT Article DE MAP DATA; MAP-IMAGE PIXELS; NEURAL NETWORK; PATTERN CLASSIFICATION AB Currently map data is stored as high-resolution digitized pixel data on CD-ROM storage devices. The copious amount of data generated from the global map data base overwhelms even high-density optical storage methods. In addition, the map user is concerned not with the high-resolution image of the map, but the actual features such as roads and rivers. By classifying the map-image pixels into separate features, the dimensionality of the data is dramatically reduced, the map is significantly decluttered, and the data is in the form most suitable for further analysis. Because of the extensive volume of the data already stored and its on-demand nature, classification speed must exceed the CD-ROM read speed so that access rates are unaffected. This paper describes a neural network approach to pattern classification applied to map pixel data. Software simulations of a sophisticated neural network show that neural networks are indeed equivalent to optimal statistical pattern classifiers. Furthermore, a fully parallel neural network hardware implementation developed at JPL, surpasses the necessary processing speed, and provides high classification accuracy. Our software as well a hardware results are presented in this paper along with a brief background in pattern classification and neural networks. RP BROWN, TX (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 13 TC 1 Z9 1 U1 0 U2 0 PU SIMULATION COUNCILS INC PI SAN DIEGO PA PO BOX 17900, SAN DIEGO, CA 92117 SN 0037-5497 J9 SIMULATION JI Simulation PD MAY PY 1992 VL 58 IS 5 BP 340 EP 347 DI 10.1177/003754979205800507 PG 8 WC Computer Science, Interdisciplinary Applications; Computer Science, Software Engineering SC Computer Science GA HX900 UT WOS:A1992HX90000008 ER PT J AU SUITOR, JW AF SUITOR, JW TI FABRICATION PROCESS-DEVELOPMENT OF OXYGEN SEPARATION SYSTEMS SO SOLID STATE IONICS LA English DT Article; Proceedings Paper CT WORKSHOP ON CERAMIC CONDUCTORS FOR SOLID STATE ELECTROCHEMICAL DEVICES CY MAY 12-14, 1991 CL SNOWBIRD, UT SP ELECT POWER RES INST, GAS RES INST RP SUITOR, JW (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 1 Z9 1 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-2738 J9 SOLID STATE IONICS JI Solid State Ion. PD MAY PY 1992 VL 52 IS 1-3 BP 277 EP 277 DI 10.1016/0167-2738(92)90116-7 PG 1 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA JD256 UT WOS:A1992JD25600033 ER PT J AU JOHNSON, TV YEATES, CM YOUNG, R AF JOHNSON, TV YEATES, CM YOUNG, R TI SPACE SCIENCE REVIEWS VOLUME ON GALILEO MISSION OVERVIEW SO SPACE SCIENCE REVIEWS LA English DT Review AB The Galileo Mission is an extremely complex undertaking. This paper provides a brief historical overview, a discussion of broad scientific objectives, and a description of the spacecraft and trajectory characteristics. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP JOHNSON, TV (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 13 TC 38 Z9 39 U1 2 U2 7 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 3 EP 21 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300002 ER PT J AU DAMARIO, LA BRIGHT, LE WOLF, AA AF DAMARIO, LA BRIGHT, LE WOLF, AA TI GALILEO TRAJECTORY DESIGN SO SPACE SCIENCE REVIEWS LA English DT Review AB The Galileo spacecraft was launched by the Space Shuttle Atlantis on October 18, 1989. A two-stage Inertial Upper Stage propelled Galileo out of Earth parking orbit to begin its 6-year interplanetary transfer to Jupiter. Galileo has already received two gravity assists: from Venus on February 10, 1990 and from Earth on December 8, 1990. After a second gravity-assist flyby of Earth on December 8, 1992, Galileo will have achieved the energy necessary to reach Jupiter. Galileo's interplanetary trajectory includes a close flyby of asteroid 951-Gaspra on October 29, 1991, and, depending on propellant availability and other factors, there may be a second asteroid flyby of 243-Ida on August 28, 1993. Upon arrival at Jupiter on December 7, 1995, the Galileo Orbiter will relay data back to Earth from an atmospheric Probe which is released five months earlier. For about 75 min, data is transmitted to the Orbiter from the Probe as it descends on a parachute to a pressure depth of 20-30 bars in the Jovian atmosphere. Shortly after the end of Probe relay, the Orbiter ignites its rocket motor to insert into orbit about Jupiter. The orbital phase of the mission, referred to as the satellite tour, lasts nearly two years, during which time Galileo will complete 10 orbits about Jupiter. On each of these orbits, there will be a close encounter with one of the three outermost Galilean satellites (Europa, Ganymede, and Callisto). The gravity assist from each satellite is designed to target the spacecraft to the next encounter with minimal expenditure of propellant. The nominal mission is scheduled to end in October 1997 when the Orbiter enters Jupiter's magnetotail. RP DAMARIO, LA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 8 TC 31 Z9 32 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 23 EP 78 PG 56 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300003 ER PT J AU FISCHER, HM MIHALOV, JD LANZEROTTI, LJ WIBBERENZ, G RINNERT, K GLIEM, FO BACH, J AF FISCHER, HM MIHALOV, JD LANZEROTTI, LJ WIBBERENZ, G RINNERT, K GLIEM, FO BACH, J TI ENERGETIC PARTICLES INVESTIGATION (EPI) SO SPACE SCIENCE REVIEWS LA English DT Review AB The Energetic Particles Investigation (EPI) instrument operates during the pre-entry phase of the Galileo Probe. The major science objective is to study the energetic particle population in the innermost regions of the Jovian magnetosphere - within 4 radii of the cloud tops - and into the upper atmosphere. To achieve these objectives the EPI instrument will make omnidirectional measurements of four different particle species - electrons, protons, alpha-particles, and heavy ions (Z > 2). Intensity profiles with a spatial resolution of about 0.02 Jupiter radii will be recorded. Three different energy range channels are allocated to both electrons and protons to provide a rough estimate of the spectral index of the energy spectra. In addition to the omnidirectional measurements, sectored data will be obtained for certain energy range electrons, protons, and alpha-particles to determine directional anisotropies and particle pitch angle distributions. The detector assembly is a two-element telescope using totally depleted, circular silicon surface-barrier detectors surrounded by a cylindrical tungsten shielding with a wall thickness of 4.86 g cm-2. The telescope axis is oriented normal to the spherical surface of the Probe's rear heat shield which is needed for heat protection of the scientific payload during the Probe's entry into the Jovian atmosphere. The material thickness of the heat shield determines the lower energy threshold of the particle species investigated during the Probe's pre-entry phase. The EPI instrument is combined with the Lightning and Radio Emission Detector (LRD) such that the EPI sensor is connected to the LRD/EPI electronic box. In this way, both instruments together only have one interface of the Probe's power, command, and data unit. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. AT&T BELL LABS,MURRAY HILL,NJ 07974. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. TECH UNIV BRAUNSCHWEIG,INST DATENVERARBEITANSLAGEN,BRAUNSCHWEIG,GERMANY. DORNIER SYST GMBH,W-7990 FRIEDRICHSHAFEN,GERMANY. RP FISCHER, HM (reprint author), UNIV KIEL,INST REINE ANGEW KERNPHYS,W-2300 KIEL 1,GERMANY. NR 14 TC 4 Z9 4 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 79 EP 90 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300004 ER PT J AU NIEMANN, HB HARPOLD, DN ATREYA, SK CARIGNAN, GR HUNTEN, DM OWEN, TC AF NIEMANN, HB HARPOLD, DN ATREYA, SK CARIGNAN, GR HUNTEN, DM OWEN, TC TI GALILEO PROBE MASS-SPECTROMETER EXPERIMENT SO SPACE SCIENCE REVIEWS LA English DT Review ID SOLAR-SYSTEM; JUPITER; ABUNDANCE; SATURN; DEUTERIUM; WATER AB The Galileo Probe Mass Spectrometer (GPMS) is a Probe instrument designed to measure the chemical and isotopic composition including vertical variations of the constituents in the atmosphere of Jupiter. The measurement will be performed by in situ sampling of the ambient atmosphere in the pressure range from approximately 150 mbar to 20 bar. In addition batch sampling will be performed for noble gas composition measurement and isotopic ratio determination and for sensitivity enhancement of non-reactive trace gases. The instrument consists of a gas sampling system which is connected to a quadrupole mass analyzer for molecular weight analysis. In addition two sample enrichment cells and one noble gas analysis cell are part of the sampling system. The mass range of the quadrupole analyzer is from 2 amu to 150 amu. The maximum dynamic range is 10(8). The detector threshold ranges from 10 ppmv for H2O to 1 ppbv for Kr and Xe. It is dependent on instrument background and ambient gas composition because of spectral interference. The threshold values are lowered through sample enrichment by a factor of 100 to 500 for stable hydrocarbons and by a factor of 10 for noble gases. The gas sampling system and the mass analyzer are sealed and evacuated until the measurement sequence is initiated after the Probe enters into the atmosphere of Jupiter. The instrument weighs 13.2 kg and the average power consumption is 13 W. The instrument follows a sampling sequence of 8192 steps and a sampling rate of two steps per second. The measurement period lasts appropriately 60 min through the nominal pressure and altitude range. C1 UNIV MICHIGAN,ANN ARBOR,MI 48109. UNIV ARIZONA,TUCSON,AZ 85721. UNIV HAWAII,HONOLULU,HI 96822. RP NIEMANN, HB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Harpold, Dan/I-3345-2013 NR 23 TC 35 Z9 35 U1 2 U2 6 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 111 EP 142 PG 32 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300006 ER PT J AU POLLACK, JB ATKINSON, DH SEIFF, A ANDERSON, JD AF POLLACK, JB ATKINSON, DH SEIFF, A ANDERSON, JD TI RETRIEVAL OF A WIND-PROFILE FROM THE GALILEO PROBE TELEMETRY SIGNAL SO SPACE SCIENCE REVIEWS LA English DT Review ID ENERGY-BALANCE; INTERNAL HEAT; PARA-HYDROGEN; JUPITER; ATMOSPHERE; PLANETS; SATURN AB Ultrastable oscillators onboard the Galileo Probe and Orbiter will permit very accurate determinations of the frequency of the Probe's telemetry signal as the Probe descends from a pressure level of several hundred mb to a level of about 20 bars. Analysis of the time-varying frequency can provide, in principle, a unique and important definition of the vertical profile of the zonal wind speed in the Jovian atmosphere. In this paper, we develop a protocol for retrieving the zonal wind profile from the Doppler shift of the measured frequency; assess the impact of a wide range of error sources on the accuracy of the retrieved wind profile; and perform a number of simulations to illustrate our technique and to assess the likely accuracy of the retrieval. Because of unavoidably large uncertainties in the absolute frequencies of the oscillators, we use time-differenced frequencies in our analysis. Nevertheless, it is possible to recover absolute wind speeds as well as wind shears, since the Orbiter/Probe geometry changes significantly during the Probe relay link. We begin with the full relativistic Doppler shift equation. Through the use of power series expansions and a basis function representation of the wind profiles, we reduce the basic equation to a set of linear equations that can be solved with standard linear least-squares techniques. There are a very large number of instrumental and environmental factors that can introduce errors into the measured signal or to the recovery of zonal winds from the data. We provide estimates of the magnitudes of all these error sources and consider the degree to which they may be reduced by a posteriori information as well as the results of calibration tests. The most important error source is the a posteriori uncertainty in the Probe's entry longitude. The accuracy of the retrieved winds is also limited by errors in the Probe's descent velocity, as obtained from atmospheric parameters measured by several Probe experiments, and in the a posteriori knowledge of secular drifts in the oscillators' frequencies during the relay link, due, for example, to aging and radiation damage. Our simulations indicate that zonal winds may be retrieved from the Doppler data to an accuracy of several m s-1. Therefore, it may be possible to discriminate among alterative models for the basic drive of the zonal winds, since they differ significantly in the implied zonal wind profile. C1 UNIV IDAHO,MOSCOW,ID 83843. SAN JOSE STATE UNIV FDN,SAN JOSE,CA 95106. JET PROP LAB,PASADENA,CA 91109. RP POLLACK, JB (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 39 TC 14 Z9 14 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 143 EP 178 PG 36 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300007 ER PT J AU RAGENT, B PRIVETTE, CA AVRIN, P WARING, JG CARLSTON, CE KNIGHT, TCD MARTIN, JP AF RAGENT, B PRIVETTE, CA AVRIN, P WARING, JG CARLSTON, CE KNIGHT, TCD MARTIN, JP TI GALILEO PROBE NEPHELOMETER EXPERIMENT SO SPACE SCIENCE REVIEWS LA English DT Review ID MOIST CONVECTION; VERTICAL STRUCTURE; ATMOSPHERE; JUPITER; ABUNDANCE; WATER; CLOUD; TROPOSPHERE AB The objective of the Nephelometer Experient aboard the Probe of the Galileo mission is to explore the vertical structure and microphysical properties of the clouds and hazes in the atmosphere of Jupiter along the descent trajectory of the Probe (nominally from 0.1 to > 10 bars). The measurements, to be obtained at least every kilometer of the Probe descent, will provide the bases for inferences of mean particle sizes, particle number densities (and hence, opacities, mass densities, and columnar mass loading) and, for non-highly absorbing particles, for distinguishing between solid and liquid particles. These quantities, especially the location of the cloud bases, together with other quantities derived from this and other experiments aboard the Probe, will not only yield strong evidence for the composition of the particles, but, using thermochemical models, for species abundances as well. The measurements in the upper troposphere will provide 'ground truth' data for correlation with remote sensing instruments aboard the Galileo Orbiter vehicle. The instrument is carefully designed and calibrated to measure the light scattering properties of the particulate clouds and hazes at scattering angles of 5.8-degree, 16-degree, 40-degree, 70-degree, and 178-degree. The measurement sensitivity and accuracy is such that useful estimates of mean particle radii in the range from about 0.2 to 20-mu can be inferred. The instrument will detect the presence of typical cloud particles with radii of about 1.0-mu, or larger, at concentrations of less than 1 cm3. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. MARTIN MARIETTA ASTRONAUT GRP,DENVER,CO 80201. RP RAGENT, B (reprint author), SAN JOSE STATE UNIV FDN,SAN JOSE,CA 95192, USA. NR 33 TC 8 Z9 8 U1 3 U2 4 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 179 EP 201 PG 23 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300008 ER PT J AU GARRARD, TL GEHRELS, N STONE, EC AF GARRARD, TL GEHRELS, N STONE, EC TI THE GALILEO HEAVY ELEMENT MONITOR SO SPACE SCIENCE REVIEWS LA English DT Review ID MAGNETOSPHERE; IONS AB The Heavy Ion Counter on the Galileo spacecraft will monitor energetic heavy nuclei of the elements from C to Ni, with energies from approximately 6 to approximately 200 MeV nucl-1. The instrument will provide measurements of trapped heavy ions in the Jovian magnetosphere, including those high-energy heavy ions with the potential for affecting the operation of the spacecraft electronic circuitry. We describe the instrument, which is a modified version of the Voyager CRS instrument. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP GARRARD, TL (reprint author), CALTECH,PASADENA,CA 91125, USA. RI Gehrels, Neil/D-2971-2012 NR 14 TC 14 Z9 14 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 305 EP 315 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300013 ER PT J AU GRUN, E FECHTIG, H HANNER, MS KISSEL, J LINDBLAD, BA LINKERT, D MAAS, D MORFILL, GE ZOOK, HA AF GRUN, E FECHTIG, H HANNER, MS KISSEL, J LINDBLAD, BA LINKERT, D MAAS, D MORFILL, GE ZOOK, HA TI THE GALILEO DUST DETECTOR SO SPACE SCIENCE REVIEWS LA English DT Review ID JUPITERS MAGNETOSPHERE; PHYSICAL PROCESSES; SOLAR-SYSTEM; RING; ORIGIN; INTERPLANETARY; EARTH AB The Galileo Dust Detector is intended to provide direct observations of dust grains with masses between 10(19) and 10(-9) kg in interplanetary space and in the Jovian system, to investigate their physical and dynamical properties as functions of the distances to the Sun, to Jupiter and to its satellites, to study its interaction with the Galilean satellites and the Jovian magnetosphere. Surface phenomena of the satellites (like albedo variations), which might be effects of meteoroid impacts will be compared with the dust environment. Electric charges of particulate matter in the magnetosphere and its consequences will be studied; e.g., the effects of the magnetic field on the trajectories of dust particles and fragmentation of particles due to electrostatic disruption. The investigation is performed with an instrument that measures the mass, speed, flight direction and electric charge of individual dust particles. It is a multicoincidence detector with a mass sensitivity 10(6) times higher than that of previous in-situ experiments which measured dust in the outer solar system. The instrument weighs 4.2 kg, consumes 2.4 W, and has a normal data transmission rate of 24 bits s-1 in nominal spacecraft tracking mode. On December 29, 1989 the instrument was switched-on. After the instrument had been configured to flight conditions cruise science data collection started immediately. In the period to May 18, 1990 at least 168 dust impacts have been recorded. For 81 of these dust grains masses and impact speeds have been determined. First flux values are given. C1 JET PROP LAB,PASADENA,CA 91109. LUND OBSERV,LUND,SWEDEN. MAX PLANCK INST EXTRATERRESTR PHYS,GARCHING,GERMANY. KERNFORSCHUNGSZENTRUM KARLSRUHE GMBH,W-7500 KARLSRUHE 1,GERMANY. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP GRUN, E (reprint author), MAX PLANCK INST NUCL PHYS,W-6900 HEIDELBERG 1,GERMANY. NR 51 TC 123 Z9 124 U1 1 U2 6 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 317 EP 340 DI 10.1007/BF00216860 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300014 ER PT J AU BELTON, MJS KLAASEN, KP CLARY, MC ANDERSON, JL ANGER, CD CARR, MH CHAPMAN, CR DAVIES, ME GREELEY, R ANDERSON, D BOLEF, LK TOWNSEND, TE GREENBERG, R HEAD, JW NEUKUM, G PILCHER, CB VEVERKA, J GIERASCH, PJ FANALE, FP INGERSOLL, AP MASURSKY, H MORRISON, D POLLACK, JB AF BELTON, MJS KLAASEN, KP CLARY, MC ANDERSON, JL ANGER, CD CARR, MH CHAPMAN, CR DAVIES, ME GREELEY, R ANDERSON, D BOLEF, LK TOWNSEND, TE GREENBERG, R HEAD, JW NEUKUM, G PILCHER, CB VEVERKA, J GIERASCH, PJ FANALE, FP INGERSOLL, AP MASURSKY, H MORRISON, D POLLACK, JB TI THE GALILEO SOLID-STATE IMAGING EXPERIMENT SO SPACE SCIENCE REVIEWS LA English DT Review ID S-TYPE ASTEROIDS; GROOVED TERRAIN; TIDAL STRESSES; GANYMEDE; IO; PATTERNS; JUPITER; EUROPA; ATMOSPHERE; SATELLITES AB The Solid State Imaging (SSI) experiment on the Galileo Orbiter spacecraft utilizes a high-resolution (1500 mm focal length) television camera with an 800 x 800 pixel virtual-phase, charge-coupled detector. It is designed to return images of Jupiter and its satellites that are characterized by a combination of sensitivity levels, spatial resolution, geometric fiedelity, and spectral range unmatched by imaging data obtained previously. The spectral range extends from approximately 375 to 1100 nm and only in the near ultra-violet region (approximately 350 nm) is the spectral coverage reduced from previous missions. The camera is approximately 100 times more sensitive than those used in the Voyager mission, and, because of the nature of the satellite encounters, will produce images with approximately 100 times the ground resolution (i.e., approximately 50 m lp-1) on the Galilean satellites. We describe aspects of the detector including its sensitivity to energetic particle radiation and how the requirements for a large full-well capacity and tong-term stability in operating voltages led to the choice of the virtual phase chip. The F/8.5 camera system can reach point sources of V(mag) approximately 11 with S/N approximately 10 and extended sources with surface brightness as low as 20 kR in its highest gain state and longest exposure mode. We describe the performance of the system as determined by ground calibration and the improvements that have been made to the telescope (same basic catadioptric design that was used in Mariner 10 and the Voyager high-resolution cameras) to reduce the scattered light reaching the detector. The images are linearly digitized 8-bits deep and, after flat-fielding, are cosmetically clean. Information 'preserving' and 'non-preserving' on-board data compression capabilities are outlined. A special "summation" mode, designed for use deep in the Jovian radiation belts, near Io, is also described. The detector is 'preflashed' before each exposure to ensure the photometric linearity. The dynamic range is spread over 3 gain states and an exposure range from 4.17 ms to 51.2 s. A low-level of radial, third-order, geometric distortion has been measured in the raw images that is entirely due to the optical design. The distortion is of the pincushion type and amounts to about 1.2 pixels in the corners of the images. It is expected to be very stable. We discuss the measurement objectives of the SSI experiment in the Jupiter system and emphasize their relationships to those of other experiments in the Galileo project. We outline objectives for Jupiter atmospheric science, noting the relationship of SSI data to that to be returned by experiments on the atmospheric entry Probe. We also outline SSI objectives for satellite surfaces, ring structure, and 'darkside' (e.g., aurorae, lightning, etc.) experiments. Proposed cruise measurement objectives that relate to encounters at Venus, Moon, Earth, Gaspra, and, possibly, Ida are also briefly outlined. The article concludes with a description of a 'fully distributed' data analysis system (HIIPS) that SSI team members intend to use at their home institutions. We also list the nature of systematic data products that will become available to the scientific community. Finally, we append a short 'historical' note outlining the responsibilities and roles of institutions and individuals that have been involved in the 14 year development of the SSI experiment so far. C1 JET PROP LAB,PASADENA,CA 91109. ITRES RES LTD,CALGARY,ALBERTA,CANADA. YORK UNIV,INST SPACE & TERR SCI,N YORK M3J 1P3,ONTARIO,CANADA. US GEOL SURVEY,MENLO PK,CA 94025. SAIC,INST PLANETARY SCI,TUCSON,AZ. RAND CORP,SANTA MONICA,CA 90406. ARIZONA STATE UNIV,TEMPE,AZ 85287. UNIV ARIZONA,TUCSON,AZ 85721. BROWN UNIV,PROVIDENCE,RI 02912. DLR,OBERPFAFFENHOFEN,GERMANY. NASA,WASHINGTON,DC 20546. CORNELL UNIV,ITHACA,NY 14853. INST GEOPHYS,HONOLULU,HI. CALTECH,PASADENA,CA 91125. US GEOL SURVEY,FLAGSTAFF,AZ 86001. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BELTON, MJS (reprint author), NATL OPT ASTRON OBSERV,TUCSON,AZ, USA. NR 74 TC 68 Z9 68 U1 0 U2 12 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 413 EP 455 PG 43 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300018 ER PT J AU CARLSON, RW WEISSMAN, PR SMYTHE, WD MAHONEY, JC APTAKER, I BAILEY, G BAINES, K BURNS, R CARPENTER, E CURRY, K DANIELSON, G ENCRENAZ, T ENMARK, H FANALE, F GRAM, M HERNANDEZ, M HICKOK, R JENKINS, G JOHNSON, T JONES, S KIEFFER, H LABAW, C LOCKHART, R MACENKA, S MARINO, J MASURSKY, H MATSON, D MCCORD, T MEHAFFEY, K OCAMPO, A ROOT, G SALAZAR, R SEVILLA, D SLEIGH, W SMYTHE, W SODERBLOM, L STEIMLE, L STEINKRAUS, R TAYLOR, F WILSON, D AF CARLSON, RW WEISSMAN, PR SMYTHE, WD MAHONEY, JC APTAKER, I BAILEY, G BAINES, K BURNS, R CARPENTER, E CURRY, K DANIELSON, G ENCRENAZ, T ENMARK, H FANALE, F GRAM, M HERNANDEZ, M HICKOK, R JENKINS, G JOHNSON, T JONES, S KIEFFER, H LABAW, C LOCKHART, R MACENKA, S MARINO, J MASURSKY, H MATSON, D MCCORD, T MEHAFFEY, K OCAMPO, A ROOT, G SALAZAR, R SEVILLA, D SLEIGH, W SMYTHE, W SODERBLOM, L STEIMLE, L STEINKRAUS, R TAYLOR, F WILSON, D TI NEAR-INFRARED MAPPING SPECTROMETER EXPERIMENT ON GALILEO SO SPACE SCIENCE REVIEWS LA English DT Review ID CLOUDS AB The Galileo Near-Infrared Mapping Spectrometer (NIMS) is a combination of imaging and spectroscopic methods. Simultaneous use of these two methods yields a powerful combination, far greater than when used individually. For geological studies of surfaces, it can be used to map morphological features, while simultaneously determining their composition and mineralogy, providing data to investigate the evolution of surface geology. For atmospheres, many of the most interesting phenomena are transitory, with unpredictable locations. With concurrent mapping and spectroscopy, such features can be found and spectroscopically analyzed. In addition, the spatial/compositional aspects of known features can be fully investigated. The NIMS experiment will investigate Jupiter and the Galilean satellites during the two year orbital operation period, commencing December 1995. Prior to that, Galileo will have flown past Venus, the Earth/Moon system (twice), and two asteroids; obtaining scientific measurements for all of these objects. The NIMS instrument covers the spectral range 0.7 to 5.2-mu, which includes the reflected-sunlight and thermal-radiation regimes for many solar system objects. This spectral region contains diagnostic spectral signatures, arising from molecular vibrational transitions (and some electronic transitions) of both solid and gaseous species. Imaging is performed by a combination of one-dimensional instrument spatial scanning, coupled with orthogonal spacecraft scan-platform motion, yielding two-dimensional images for each of the NIMS wavelengths. The instrument consists of a telescope, with one dimension of spatial scanning, and a diffraction grating spectrometer. Both are passively cooled to low temperatures in order to reduce background photon shot noise. The detectors consist of an array of indium antimonide and silicon photo-voltaic diodes, contained within a focal-plane-assembly, and cooled to cryogenic temperatures using a radiative cooler. Spectral and spatial scanning is accomplished by electro-mechanical devices, with motions executed using commandable instrument modes. Particular attention was given to the thermal and contamination aspects of the Galileo spacecraft, both of which could profoundly affect NIMS performance. Various protective measures have been implemented, including shades to protect against thruster firings as well as thermal radiation from the spacecraft. RP CARLSON, RW (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 20 TC 126 Z9 126 U1 2 U2 13 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 457 EP 502 PG 46 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300019 ER PT J AU HORD, CW MCCLINTOCK, WE STEWART, AIF BARTH, CA ESPOSITO, LW THOMAS, GE SANDEL, BR HUNTEN, DM BROADFOOT, AL SHEMANSKY, DE AJELLO, JM LANE, AL WEST, RA AF HORD, CW MCCLINTOCK, WE STEWART, AIF BARTH, CA ESPOSITO, LW THOMAS, GE SANDEL, BR HUNTEN, DM BROADFOOT, AL SHEMANSKY, DE AJELLO, JM LANE, AL WEST, RA TI GALILEO ULTRAVIOLET SPECTROMETER EXPERIMENT SO SPACE SCIENCE REVIEWS LA English DT Review ID NIGHT AIRGLOW; EMISSION; JUPITER; VENUS AB The Galileo ultraviolet spectrometer experiment uses data obtained by the Ultraviolet Spectrometer (UVS) mounted on the pointed orbiter scan platform and from the Extreme Ultraviolet Spectrometer (EUVS) mounted on the spinning part of the orbiter with the field of view perpendicular to the spin axis. The UVS is a Ebert-Fastie design that covers the range 113-432 nm with a wavelength resolution of 0.7 nm below 190 and 1.3 nm at longer wavelengths. The UVS spatial resolution is 0.4 deg x 0.1 deg for illuminated disc observations and 1 deg x 0.1 deg for limb geometries. The EUVS is a Voyager design objective grating spectrometer, modified to cover the wavelength range from 54 to 128 nm with wavelength resolution 3.5 nm for extended sources and 1.5 nm for point sources and spatial resolution of 0.87 deg x 0.17 deg. The EUVS instrument will follow up on the many Voyager UVS discoveries, particularly the sulfur and oxygen ion emissions in the lo torus and molecular and atomic hydrogen auroral and airglow emissions from Jupiter. The UVS will obtain spectra of emission, absorption, and scattering features in the unexplored, by spacecraft, 170-432 nm wavelength region. The UVS and EUVS instruments will provide a powerful instrument complement to investigate volatile escape and surface composition of the Galilean satellites, the lo plasma torus, micro- and macro-properties of the Jupiter clouds, and the composition structure and evolution of the Jupiter upper atmosphere. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. JET PROP LAB,PASADENA,CA 91109. RP HORD, CW (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309, USA. NR 23 TC 37 Z9 37 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 503 EP 530 PG 28 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300020 ER PT J AU HOWARD, HT ESHLEMAN, VR HINSON, DP KLIORE, AJ LINDAL, GF WOO, R BIRD, MK VOLLAND, H EDENHOFER, P PATZOLD, M PORSCHE, H AF HOWARD, HT ESHLEMAN, VR HINSON, DP KLIORE, AJ LINDAL, GF WOO, R BIRD, MK VOLLAND, H EDENHOFER, P PATZOLD, M PORSCHE, H TI GALILEO RADIO SCIENCE INVESTIGATIONS SO SPACE SCIENCE REVIEWS LA English DT Review ID OCCULTATION MEASUREMENTS; MAGNETIC-FIELD; SCINTILLATION OBSERVATIONS; SCATTERING OBSERVATIONS; VOYAGER MEASUREMENTS; HELIUM ABUNDANCE; RADAR ECHOES; WHITE-LIGHT; PIONEER 10; ATMOSPHERE AB The radio science investigations planned for Galileo's 6-year flight to and 2-year orbit of Jupiter use as their instrument the dual-frequency radio system on the spacecraft operating in conjunction with various US and German tracking stations on Earth. The planned radio propagation experiments are based on measurements of absolute and differential propagation time delay, differential phase delay, Doppler shift, signal strength, and polarization. These measurements will be used to study: the atmospheric and ionospheric structure, constituents, and dynamics of Jupiter; the magnetic field of Jupiter; the diameter of Io, its ionospheric structure, and the distribution of plasma in the Io torus; the diameters of the other Galilean satellites, certain properties of their surfaces, and possibly their atmospheres and ionospheres; and the plasma dynamics and magnetic field of the solar corona. The spacecraft system used for these investigations is based on Voyager heritage but with several important additions and modifications that provide linear rather than circular polarization on the S-band downlink signal, the capability to receive X-band uplink signals, and a differential downlink ranging mode. Collaboration between the investigators and the spacecraft communications engineers has resulted in the first highly-stable, dual-frequency, spacecraft radio system suitable for simultaneous measurements of all the parameters normally attributed to radio waves. C1 JET PROP LAB,PASADENA,CA 91109. UNIV BONN,INST RADIOASTRON,W-5300 BONN,GERMANY. RUHR UNIV BOCHUM,INST HF TECH,W-4630 BOCHUM,GERMANY. DEUTSCH FORSCH ANSTALT LUFT & RAUMFAHRT,OBERPFAFFENHOFEN,GERMANY. RP HOWARD, HT (reprint author), STANFORD UNIV,CTR RADAR ASTRON,STANFORD,CA 94305, USA. NR 68 TC 24 Z9 24 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 565 EP 590 PG 26 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300022 ER PT J AU ANDERSON, JD ARMSTRONG, JW CAMPBELL, JK ESTABROOK, FB KRISHER, TP LAU, EL AF ANDERSON, JD ARMSTRONG, JW CAMPBELL, JK ESTABROOK, FB KRISHER, TP LAU, EL TI GRAVITATION AND CELESTIAL MECHANICS INVESTIGATIONS WITH GALILEO SO SPACE SCIENCE REVIEWS LA English DT Review ID TRACKING DATA; RADIATION; SEARCH; FIELD; VERIFICATION; VARIABILITY; PIONEER-10; SATELLITES; JUPITER; LIMITS AB The gravitation and celestial mechanics investigations during the cruise phase and Orbiter phase of the Galileo mission depend on Doppler and ranging measurements generated by the Deep Space Network (DSN) at its three spacecraft tracking sites in California, Australia, and Spain. Other investigations which also rely on DSN data, and which like ours fall under the general discipline of spacecraft radio science, are described in a companion paper by Howard et al. (1992). We group our investigations into four broad categories as follows: (1) the determination of the gravity fields of Jupiter and its four major satellites during the orbital tour, (2) a search for gravitational radiation as evidenced by perturbations to the coherent Doppler link between the spacecraft and Earth, (3) the mathematical modeling, and by implication tests, of general relativistic effects on the Doppler and ranging data during both cruise and orbiter phases, and (4) an improvement in the ephemeris of Jupiter by means of spacecraft ranging during the Orbiter phase. The gravity fields are accessible because of their effects on the spacecraft motion, determined primarily from the Doppler data. For the Galilean satellites we will determine second degree and order gravity harmonics that will yield new information on the central condensation and likely composition of material within these giant satellites (Hubbard and Anderson, 1978). The search for gravitational radiation is being conducted in cruise for periods of 40 days centered around solar opposition. During these times the radio link is least affected by scintillations introduced by solar plasma. Our sensitivity to the amplitude of sinusoidal signals approaches 10(-15) in a band of gravitational frequencies between 10(-4) and 10(-3) Hz, by far the best sensitivity obtained in this band to date. In addition to the primary objectives of our investigations, we discuss two secondary objectives: the determination of a range fix on Venus during the flyby on 10 February, 1990, and the determination of the Earth's mass (GM) from the two Earth gravity assists, EGA1 in December 1990 and EGA2 in December 1992. RP ANDERSON, JD (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 42 TC 16 Z9 16 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-6308 J9 SPACE SCI REV JI Space Sci. Rev. PD MAY PY 1992 VL 60 IS 1-4 BP 591 EP 610 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HW943 UT WOS:A1992HW94300023 ER PT J AU SAATCHI, SS LANG, RH AF SAATCHI, SS LANG, RH TI MEAN WAVE-PROPAGATION IN A SLAB OF ONE-DIMENSIONAL DISCRETE RANDOM MEDIUM SO WAVE MOTION LA English DT Article ID RADIATIVE TRANSPORT-THEORY; POWER STATISTICS AB A study has been made of the propagation of time harmonic waves through a one-dimensional medium of discrete scatterers randomly positioned over a finite interval L. The random medium is modeled by a Poisson impulse process with density lambda. The invariant imbedding procedure is employed to obtain a set of initial value stochastic differential equations for the field inside the medium and the reflection coefficient of the layer. By using the Markov properties of the Poisson impulse process, exact integro-differential equations of the Kolmogorov-Feller type are derived for the probability density function of the reflection coefficient and the field. When the concentration of the scatterers is low. a two variable perturbation method in small lambda is used to obtain an approximate solution for the mean field. It is shown that this solution, which varies exponentially with respect to lambda-L. agrees exactly with the mean field obtained by Foldy's approximate method. C1 GEORGE WASHINGTON UNIV,DEPT ELECT ENGN & COMP SCI,WASHINGTON,DC 20052. RP SAATCHI, SS (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 33 TC 1 Z9 1 U1 1 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0165-2125 J9 WAVE MOTION JI Wave Motion PD MAY PY 1992 VL 15 IS 4 BP 301 EP 314 DI 10.1016/0165-2125(92)90051-3 PG 14 WC Acoustics; Mechanics; Physics, Multidisciplinary SC Acoustics; Mechanics; Physics GA HW703 UT WOS:A1992HW70300001 ER PT J AU MARTINEZ, LF MARQUES, RE MCCLURE, JC NUNES, AC AF MARTINEZ, LF MARQUES, RE MCCLURE, JC NUNES, AC TI FRONT SIDE KEYHOLE DETECTION IN ALUMINUM-ALLOYS SO WELDING JOURNAL LA English DT Article C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,MAT & PROC LAB,HUNTSVILLE,AL 35812. RP MARTINEZ, LF (reprint author), UNIV TEXAS,DEPT MET & MAT ENGN,EL PASO,TX 79968, USA. NR 6 TC 14 Z9 17 U1 0 U2 1 PU AMER WELDING SOC PI MIAMI PA PO BOX 351040, MIAMI, FL 33135 SN 0043-2296 J9 WELD J JI Weld. J. PD MAY PY 1992 VL 71 IS 5 BP 49 EP 52 PG 4 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA HR966 UT WOS:A1992HR96600007 ER PT J AU SALEEB, AF CHANG, TYP ARNOLD, SM AF SALEEB, AF CHANG, TYP ARNOLD, SM TI ON THE DEVELOPMENT OF EXPLICIT ROBUST SCHEMES FOR IMPLEMENTATION OF A CLASS OF HYPERELASTIC MODELS IN LARGE-STRAIN ANALYSIS OF RUBBERS SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article ID TENSOR; FORMULATION AB The issue of developing effective and robust schemes to implement a class of the Ogden-type hyperelastic constitutive models, for large-strain analysis of rubber-like materials, is addressed. To this end, explicit forms for the corresponding material tangent-stiffness tensors are developed, and these are valid for the entire deformation range; i.e. with both distinct as well as repeated principal-stretch values. Throughout the analysis the various implications of the underlying property of separability of the strain-energy functions are exploited, thus leading to compact final forms of the tensor expressions. In particular, this facilitated the treatment of the complex cases of uncoupled volumetric/deviatoric formulations for incompressible materials, which are becoming increasingly popular in recent years. The forms derived are also amenable for use with symbolic-manipulation packages for systematic code generation. C1 NASA,RES CTR,CLEVELAND,OH 44135. RP SALEEB, AF (reprint author), UNIV AKRON,DEPT CIVIL ENGN,AKRON,OH 44325, USA. NR 30 TC 14 Z9 15 U1 0 U2 2 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD APR 30 PY 1992 VL 33 IS 6 BP 1237 EP 1249 DI 10.1002/nme.1620330609 PG 13 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA HN223 UT WOS:A1992HN22300008 ER PT J AU ANDREAE, MO CHAPUIS, A CROS, B FONTAN, J HELAS, G JUSTICE, C KAUFMAN, YJ MINGA, A NGANGA, D AF ANDREAE, MO CHAPUIS, A CROS, B FONTAN, J HELAS, G JUSTICE, C KAUFMAN, YJ MINGA, A NGANGA, D TI OZONE AND AITKEN NUCLEI OVER EQUATORIAL AFRICA - AIRBORNE OBSERVATIONS DURING DECAFE-88 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPOSPHERIC OZONE; CARBON-MONOXIDE; BOUNDARY-LAYER; SURFACE OZONE; AMAZONIA; EMISSION; TROPICS; AIR; O3 AB We determined the distribution of ozone (O3) and Aitken condensation nuclei (CN) over the rain forest in equatorial Africa during February 12-25, 1988. A pronounced O3 maximum with levels up to 70 ppbv was present in a layer between 1 and 3 km altitude throughout the period. It coincided with a CO maximum and with high levels of CO2 and gaseous organic acids. In general, the vertical distribution of CN was similar to that of O3, with number densities ranging up to approximately 3000 cm-3. Dense haze was visible within this layer. O3 and CN decreased sharply above the haze layer to values typical of the remote troposphere. Survey flights showed little change in levels of O3 and CN or in their vertical distribution over distances of hundreds of kilometers. Meteorological observations suggest that this ozone and particulate enriched layer is formed from air masses which originate in northern Africa and subsequently advect over dry tropical regions where biomass burning emits large amounts of aerosols, CO, NO, and hydrocarbons. These air masses then become trapped in the equatorial region between the near-surface monsoon flow from the southeast and the permanent easterly flow above 3-4 km. Differences in the vertical distribution of O3 and CN result from the removal of O3 by surface uptake and reactions with NO and hydrocarbons, leading to surface O3 concentrations near zero and a steep O3 gradient through the subcloud layer at night. During the day this gradient is reduced by convective mixing. CN concentrations showed no pronounced gradients in the subcloud layer, consistent with the absence of a strong sink for CN at the ground. CN gradients near the surface suggest emission of particles from the forest vegetation or from biomass burning. C1 UNIV TOULOUSE, AEROL LAB, TOULOUSE, FRANCE. LAB PHYS ATMOSPHERE, BRAZZAVILLE, CONGO PEOPL REP. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP ANDREAE, MO (reprint author), MAX PLANCK INST CHEM, BIOGEOCHEM ABT, POB 3060, W-6500 MAINZ, GERMANY. RI Andreae, Meinrat/B-1068-2008 OI Andreae, Meinrat/0000-0003-1968-7925 NR 42 TC 76 Z9 76 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 30 PY 1992 VL 97 IS D6 BP 6137 EP 6148 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HR486 UT WOS:A1992HR48600002 ER PT J AU DUFFY, DG AF DUFFY, DG TI ON THE GENERATION OF OCEANIC SURFACE-WAVES BY UNDERWATER VOLCANIC EXPLOSIONS SO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH LA English DT Article ID LEAKING MODES; AXISYMMETRIC BOREHOLES; TSUNAMIS AB The oceanic surface waves generated by submarine volcanism are modeled as the response of a compressible ocean to an underwater point explosion at an arbitrary depth over an elastic half-space. We generalize the work of Kajiura and Miyoshi by allowing the elastic sea floor to influence both the sound and surface gravity waves. The classic work of Press and Ewing is extended to allow for the movement of the oceanic free surface. From numerical inversion techniques, we find that most of the energy is radiated away as surface gravity waves. A mixture of direct and reflected P- (compressional) and S-type (distortional) head waves may produce high-frequency, large-amplitude oscillations in the sea surface. RP DUFFY, DG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 41 TC 3 Z9 3 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-0273 J9 J VOLCANOL GEOTH RES JI J. Volcanol. Geotherm. Res. PD APR 30 PY 1992 VL 50 IS 3 BP 323 EP 344 DI 10.1016/0377-0273(92)90100-R PG 22 WC Geosciences, Multidisciplinary SC Geology GA HY659 UT WOS:A1992HY65900007 ER PT J AU WATKINS, R WIDROW, LM AF WATKINS, R WIDROW, LM TI ASPECTS OF REHEATING IN 1ST-ORDER INFLATION SO NUCLEAR PHYSICS B LA English DT Article ID EXTENDED INFLATION; CHAOTIC INFLATION; SYMMETRY-BREAKING; UNIVERSE; COSMOLOGY; VACUUM AB We study reheating in theories where inflation is completed by a first-order phase transition. In these scenarios, the Universe decays from its false vacuum state by bubble nucleation. We follow the Universe through the phase transition beginning with bubble nucleation and ending with particle production from wall collisions. In the first stage of reheating. vacuum energy is converted into kinetic energy for the bubble walls. To help understand this phase we derive a simple expression for the equation of state of a universe filled with expanding bubbles. Eventually the bubble walls collide. The production of particles during wall collisions from both classical and quantum processes is examined. We study classical scalar wave production through numerical simulations of two-bubble collisions, clarifying and extending previous work by Hawking, Moss and Stewart. We go on to discuss direct quantum particle production due to couplings between the inflation and other fields. We calculate particle production for colliding walls in both sine-Gordon and phi-4 theories. Our results indicate that both classical and quantum processes are quite efficient for models with double-well potentials, but can be suppressed for models with potentials that are periodic. In addition, we show that particles with masses well above the mass of the inflation can be produced if the walls are highly relativistic. The relevance of our work for recently proposed models of first-order inflation is discussed. C1 FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV TORONTO,CANADIAN INST THEORET ASTROPHYS,TORONTO M5S 1A1,ONTARIO,CANADA. RP WATKINS, R (reprint author), UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637, USA. NR 34 TC 22 Z9 22 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0550-3213 J9 NUCL PHYS B JI Nucl. Phys. B PD APR 27 PY 1992 VL 374 IS 2 BP 446 EP 468 DI 10.1016/0550-3213(92)90362-F PG 23 WC Physics, Particles & Fields SC Physics GA HR445 UT WOS:A1992HR44500011 ER PT J AU DODELSON, S FRIEMAN, JA TURNER, MS AF DODELSON, S FRIEMAN, JA TURNER, MS TI CONSTRAINTS TO THE DECAYS OF DIRAC NEUTRINOS FROM SN-1987A SO PHYSICAL REVIEW LETTERS LA English DT Article ID SUPERNOVA 1987A; BETA-SPECTRUM; 17-KEV NEUTRINO; SN1987A; MASSES; BOUNDS; LIMITS; BURST; S-35 AB The wrong-helicity states of keV-mass Dirac neutrinos are emitted copiously from the cores of newly born neutron stars, including that associated with SN 1987A. If they decay into proper-helicity neutrinos-v(e), v(mu), or v(e)BAR, or v(mu)BAR-they should have produced distinctive high-energy events in the Kamiokande II and Irvine-Michigan-Brookhaven detectors. The absence of such events excludes these decay modes for a Dirac neutrino of mass between order 1 and 300 keV and lifetime 10(-9)[m(v)/(1 keV)] sec less than or similar to tau less than or similar to 5 x 10(7)[m(v)/(1 keV)] sec. This places severe constraints on models for Simpson's 17-keV neutrino. C1 UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. RP DODELSON, S (reprint author), FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. NR 39 TC 18 Z9 18 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 APR 27 PY 1992 VL 68 IS 17 BP 2572 EP 2575 DI 10.1103/PhysRevLett.68.2572 PG 4 WC Physics, Multidisciplinary SC Physics GA HQ440 UT WOS:A1992HQ44000002 ER PT J AU ROOD, R DOUGLASS, A WEAVER, C AF ROOD, R DOUGLASS, A WEAVER, C TI TRACER EXCHANGE BETWEEN TROPICS AND MIDDLE LATITUDES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERE; WINTER AB The interaction between the tropics and middle latitudes is studied using a tracer emitted at 50 hPa along a great circle route between Los Angeles, USA and Sydney, Australia. Though designed to examine the impact of stratospheric aircraft, the study more generally addresses the transport between tropics and middle latitudes for a three month period from January through March 1989. The results show that air is transported from the tropics to middle latitudes by planetary scale and tropospheric cyclonic scale waves. Except for intrusions by these wave events, the tropics are substantially isolated throughout the lower stratosphere. These waves draw material out of the tropics which ends up in the middle latitude westerly jets, with little material entering the winter polar latitudes prior to the springtime transition. The summer southern hemisphere is characterized by tracer being drawn out in streamers that extend from north and west to south and east. The material in the tropics is zonally asymmetric. The material that reaches the troposphere comes down in the synoptic scale eddies and is concentrated in the middle latitude jet stream. These characteristics are similar to those observed during the dispersion of volcanic clouds. RP ROOD, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 916,GREENBELT,MD 20771, USA. RI Douglass, Anne/D-4655-2012; Rood, Richard/C-5611-2008 OI Rood, Richard/0000-0002-2310-4262 NR 16 TC 24 Z9 24 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 24 PY 1992 VL 19 IS 8 BP 805 EP 808 DI 10.1029/92GL00526 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HR641 UT WOS:A1992HR64100019 ER PT J AU SLAVIN, JA SMITH, MF MAZUR, EL BAKER, DN IYEMORI, T SINGER, HJ GREENSTADT, EW AF SLAVIN, JA SMITH, MF MAZUR, EL BAKER, DN IYEMORI, T SINGER, HJ GREENSTADT, EW TI ISEE-3 PLASMOID AND TCR OBSERVATIONS DURING AN EXTENDED INTERVAL OF SUBSTORM ACTIVITY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID TRAVELING COMPRESSION REGIONS; DISTANT MAGNETOTAIL AB On April 9-11, 1983, the ISEE 3 spacecraft was continuously located within the Earth's magnetotail for more than 36 hours at downstream distances of X = -76 to -80 R(e). During this span of time, 12 major intervals of substorm activity were observed in the AL index with good ISEE 3 telemetry coverage for 11 of them. In addition, there were two small substorms outside of these intervals, both with complete observations in the distant tail. This unusual ISEE 3 data set provides a unique opportunity to test the predictions of the near-Earth neutral line model. In particular, we examine the hypothesis that energy stored in the tail lobes during the growth phase is later dissipated, in part, through the release of one or more plasmoids following expansion phase onset. Clear growth phase enhancements in the lobe magnetic field intensity preceded the onsets of nine of the substorms. Plasmoids, or their lobe signatures, traveling compression regions (TCRs), were observed at ISEE 3 in association with all 11 of the major substorm intervals for which there were ISEE observations as well as for the two small substorms. No plasmoids or TCRs were observed in the absence of substorm activity. If these ISEE 3 observations are representative, then the release of plasmoids down the tail may be a feature common to all substorms. C1 KYOTO UNIV,FAC SCI,DATA ANAL CTR GEOMAGNETISM,KYOTO 606,JAPAN. PHILLIPS LAB,DIV SPACE PHYS,BEDFORD,MA 01731. TRW SYST GRP,DEPT SPACE SCI,REDONDO BEACH,CA 90278. RP SLAVIN, JA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 696,GREENBELT,MD 20771, USA. RI Slavin, James/H-3170-2012 OI Slavin, James/0000-0002-9206-724X NR 16 TC 53 Z9 53 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR 24 PY 1992 VL 19 IS 8 BP 825 EP 828 DI 10.1029/92GL00394 PG 4 WC Geosciences, Multidisciplinary SC Geology GA HR641 UT WOS:A1992HR64100024 ER PT J AU DAVIS, S WYDEVEN, T YUM, A NEUKOM, C AF DAVIS, S WYDEVEN, T YUM, A NEUKOM, C TI A COMPUTATIONAL AND EXPERIMENTAL-STUDY OF UNSTEADY FACILITATED TRANSPORT SO JOURNAL OF MEMBRANE SCIENCE LA English DT Article DE FACILITATED TRANSPORT; LIQUID MEMBRANES ID MEMBRANES AB Unsteady facilitated transport of nitric oxide across a thin liquid membrane of formamide containing ferrous chloride as a facilitator is investigated both experimentally and computationally. Predicted nitric oxide transport and flux are compared with experiments first reported by Ward. Unsteady transport is predicted qualitatively quite well, but precise quantitative agreement between the differential equation model and experiment depends on an accurate determination of the transport coefficients, especially the diffusion constants. C1 NASA,AMES RES CTR,DIV ADV LIFE SUPPORT,MOFFETT FIELD,CA 94035. RP DAVIS, S (reprint author), NASA,AMES RES CTR,DIV FLUID DYNAM,MOFFETT FIELD,CA 94035, USA. NR 12 TC 2 Z9 2 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0376-7388 J9 J MEMBRANE SCI JI J. Membr. Sci. PD APR 24 PY 1992 VL 69 IS 1-2 BP 99 EP 108 DI 10.1016/0376-7388(92)80171-F PG 10 WC Engineering, Chemical; Polymer Science SC Engineering; Polymer Science GA HW615 UT WOS:A1992HW61500010 ER PT J AU PALEY, MS FRAZIER, DO ABELEDEYEM, H MCMANUS, SP ZUTAUT, SE AF PALEY, MS FRAZIER, DO ABELEDEYEM, H MCMANUS, SP ZUTAUT, SE TI SYNTHESIS, VAPOR GROWTH, POLYMERIZATION, AND CHARACTERIZATION OF THIN-FILMS OF NOVEL DIACETYLENE DERIVATIVES OF PYRROLE - THE USE OF COMPUTER MODELING TO PREDICT CHEMICAL AND OPTICAL-PROPERTIES OF THESE DIACETYLENES AND POLY(DIACETYLENES) SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID PARAMETERS AB In the present work two diacetylene derivatives of pyrrole (compounds 1 and 2), which are predicted by semiempirical AM1 calculations to have very different properties, are synthesized; the polymerizability of these diacetylenes in the solid state is determined; and the results are compared to the computer predictions. Diacetylene 1 is novel in that the monomer is a liquid at room temperature; this may allow for the possibility of polymerization in the liquid state as well as the solid state. Thin poly(diacetylene) film are obtained from compound 1 by growing films of the monomer using vapor deposition and polymerizing with UV light; these films are then characterized. Interestingly, while the poly(diacetylene) from 1 does not possess good nonlinear optical properties, the monomer exhibits very good third-order nonlinear optical effects (e.g., phase conjugation) in solution. Dilute acetone solutions of the monomer 1 give intensity-dependent refractive indices (n2) on the order of 10(-6) esu (chi(3) values on the order of 10(-7) esu); these are 10(6) times better than for CS2. C1 UNIV ALABAMA,DEPT CHEM,HUNTSVILLE,AL 35899. UNIV ALABAMA,MAT SCI PROGRAM,HUNTSVILLE,AL 35899. RP PALEY, MS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 21 TC 35 Z9 35 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD APR 22 PY 1992 VL 114 IS 9 BP 3247 EP 3251 DI 10.1021/ja00035a013 PG 5 WC Chemistry, Multidisciplinary SC Chemistry GA HQ814 UT WOS:A1992HQ81400013 ER PT J AU SRIVASTAVA, V JARZEMBSKI, MA BOWDLE, DA AF SRIVASTAVA, V JARZEMBSKI, MA BOWDLE, DA TI COMPARISON OF CALCULATED AEROSOL BACKSCATTER AT 9.1-MU-M AND 2.1-MU-M WAVELENGTHS SO APPLIED OPTICS LA English DT Note DE SCATTERING; AEROSOL MICROPHYSICS AB Calculated aerosol backscatter for three common atmospheric aerosol compositions is higher at 2.1-mu-m than at 9.1-mu-m for low backscatter conditions and almost comparable for high backscatter conditions. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,REMOTE SENSING BRANCH,HUNTSVILLE,AL 35812. UNIV ALABAMA,JOHNSON RES CTR,HUNTSVILLE,AL 35899. RP SRIVASTAVA, V (reprint author), UNIV SPACE RES ASSOC,4950 CORP DR,HUNTSVILLE,AL 35806, USA. NR 8 TC 23 Z9 23 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD APR 20 PY 1992 VL 31 IS 12 BP 1904 EP 1906 PG 3 WC Optics SC Optics GA HP607 UT WOS:A1992HP60700001 PM 20720832 ER PT J AU BECKER, JF SAUKE, TB LOEWENSTEIN, M AF BECKER, JF SAUKE, TB LOEWENSTEIN, M TI STABLE ISOTOPE ANALYSIS USING TUNABLE DIODE-LASER SPECTROSCOPY SO APPLIED OPTICS LA English DT Article DE DIODE LASER; ISOTOPIC RATIO; C-13/C-12; CARBON DIOXIDE; LASER SPECTROSCOPY ID SEMICONDUCTOR-LASERS; SPECTRAL CHARACTERISTICS; LINEWIDTH; CARBON; SPECTROMETER; POWER AB Measurements of ratios of stable isotopes are used in such diverse fields as petroleum prospecting, medical diagnostics, and planetary exploration. The narrow emission linewidth available from tunable diode lasers permits high-resolution infrared absorption measurements of closely spaced isotopic rovibrational lines. Our dual beam spectrometer uses the sweep integration technique in a spectral region where adjacent spectral lines are of approximately equal absorbance at the expected isotopic abundances. The experimental results reported here indicate that isotopic ratios of carbon in carbon dioxide can be measured to an accuracy of better than 0.4%. This laser spectroscopic technique offers an alternative to the mass spectrometric technique for in situ isotopic analysis in field studies, as well as flight and space applications. C1 NASA, AMES RES CTR, ATMOSPHER CHEM & DYNAM BRANCH, MOFFETT FIELD, CA 94035 USA. NASA, AMES RES CTR, SOLAR SYST EXPLORAT BRANCH, MOFFETT FIELD, CA 94035 USA. RP SAN JOSE STATE UNIV, DEPT PHYS, 1 WASHINGTON SQ, SAN JOSE, CA 95192 USA. NR 32 TC 50 Z9 50 U1 1 U2 10 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 1559-128X EI 2155-3165 J9 APPL OPTICS JI Appl. Optics PD APR 20 PY 1992 VL 31 IS 12 BP 1921 EP 1927 PG 7 WC Optics SC Optics GA HP607 UT WOS:A1992HP60700008 PM 20720839 ER PT J AU PARMAR, DS AF PARMAR, DS TI BOUNDARY-LAYER ELASTO-OPTIC SWITCHING IN FERROELECTRIC LIQUID-CRYSTALS SO APPLIED PHYSICS LETTERS LA English DT Article AB Utilizing a simple new configuration, one rigid surface and the other exposed directly to the gas flow, elasto-optic switching in thin (approximately 2-mu-m) ferroelectric liquid crystal films is observed when a gas flow is impingement in the plane of smectic layers. The elasto-optic response caused by the shear stress is large, fast, and reversible. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 9 TC 3 Z9 3 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD APR 20 PY 1992 VL 60 IS 16 BP 1954 EP 1956 DI 10.1063/1.107135 PG 3 WC Physics, Applied SC Physics GA HP471 UT WOS:A1992HP47100012 ER PT J AU MICHALITSIANOS, AG KAFATOS, M MEIER, SR AF MICHALITSIANOS, AG KAFATOS, M MEIER, SR TI FE-II FLUORESCENCE AND ANOMALOUS C-IV DOUBLET INTENSITIES IN SYMBIOTIC NOVAE SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES SYMBIOTIC; NOVAE, CATACLYSMIC VARIABLES; STARS EMISSION-LINE, BE; ULTRAVIOLET; STARS ID RX PUPPIS; RR-TEL; STARS; SPECTRA AB Symbiotic stars frequently exhibit anomalous C IV lambda-lambda-1548.2, 1550.8 doublet flux ratios, in which the intensity ratio of the blue and red doublet members is below the optically thick limit of unity. Three symbiotic stars (RR Tel, RX Pup, and AG Peg) have been investigated in detail with high-resolution spectra obtained from the International Ultraviolet Explorer (IUE) archives. We have examined the deficit of C IV lambda-1548.2 emission relative to lambda-1550.8 in context with the fluorescent pumping of the Fe II multiplet (45.01) lambda-1548.204 by the C IV lambda-1548.2 line. In RR Tel the C IV lambda-1548.2 flux is correlated with the intensities of fluorescent-excited Fe II lines formed by the downward cascades from the yH-4(11/2)0 upper level. This suggests that a circumstellar Fe II forming region in RR Tel responds to variations of the C IV line strength, which provides further evidence in support of Fe II fluorescence in UV spectra of symbiotic stars first identified by Johansson. During periods when the C IV I(lambda-1548.2)/I(lambda-1550.8) ratio in RX Pup is significantly less than the optically thick limit of unity, we find that the flux deficit of C IV lambda-1548.2 is approximately equal to the combined flux of the Fe II Bowen-pumped a4F9/2 --> yH-4(11/2)0 transition. This could explain the anomalous C IV ratios observed in this system and several deep absorption features in the C IV lambda-1548 line profile, when the C IV flux ratio was substantially less than the optically thick limit of unity. Unlike RR Tel and AG Peg in which the velocity centroids of the Fe II Bowen lines correspond to the peak emission of the C IV lambda-1548.2 line, the Bowen-pumped Fe II lines in RX Pup exhibit a velocity range 0 less-than-or-equal-to upsilon(Fe II) less-than-or-equal-to + 80 km s-1. This could reflect the differential motion of individual gas parcels within an orbiting cloud that obscured the Mira and hot ionizing object, consistent with the model proposed by Whitelock et al. to explain the photometric behavior of RX Pup between 1982 and 1983. The cloud would be the source of Fe II fluorescent emission and would explain why the anomalous C IV doublet intensities were observed during a 3 yr period when the V and J photometric bands indicated a decrease in light. C1 GEORGE MASON UNIV,DEPT PHYS,FAIRFAX,VA 22030. RP MICHALITSIANOS, AG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6841,GREENBELT,MD 20771, USA. NR 21 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1992 VL 389 IS 2 BP 649 EP 656 DI 10.1086/171237 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HP119 UT WOS:A1992HP11900016 ER PT J AU CANUTO, VM MAZZITELLI, I AF CANUTO, VM MAZZITELLI, I TI FURTHER IMPROVEMENTS OF A NEW MODEL FOR TURBULENT CONVECTION IN STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE CONVECTION; STARS INTERIORS; SUN INTERIOR; TURBULENCE ID THERMONUCLEAR REACTION-RATES; AGE; EVOLUTION; HYDROGEN; CLUSTERS; HELIUM; SOLAR; MASS; SUN AB In this paper we analyze the effect of several improvements of the input physics of a recent model for stellar turbulent convection. We first study the effect of (1) the inclusion of a variable molecular weight (Cox & Giuli's variable Q) and (2) the use of the newest opacities of Rogers & Iglesias. On the basis of the evolutionary tracks for the Sun (Fig. 2, curves 1 and 2), we conclude that the original model for turbulence with the mixing length LAMBDA = z, together with Q not-equal 1 and the new opacities, yields a fit to the solar T(eff) within 0.5%. The model has no adjustable parameters. Second, we propose a formulation of the mixing length LAMBDA that extends the purely nonlocal LAMBDA = z expression used in our previous work so as to include local effects. We derive the expression LAMBDA = alpha(S, a)z, where S = 160A2(NABLA - NABLA(ad)) and where 1 - a represents the weight of local effects. The new expression generalizes both the mixing-length theory (MLT) phenomenological expression LAMBDA = alpha-H(p), as well as our model LAMBDA = z. By adjusting the parameter a we can achieve an even better fit to the solar T(eff). However, we also conclude that as long as one is interested in evolutionary studies only, the new version of the mixing length is not quite necessary since the previous model has no free parameters and yet yields a fit to T(eff) within 0.5%. We point out, however, that this new model for LAMBDA may become instrumental in helioseismology where one needs to fit the solar radius considerably more accurately than in evolutionary studies. Finally, in section 7 we use qualitative and quantitative arguments to discuss the new model versus the standard MLT and give reasons why we believe that the MLT should be abandoned. C1 CNR,IST ASTROFIS SPAZIALE,I-00044 FRASCATI,ITALY. RP CANUTO, VM (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 28 TC 192 Z9 192 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1992 VL 389 IS 2 BP 724 EP 730 DI 10.1086/171245 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HP119 UT WOS:A1992HP11900024 ER PT J AU MANDZHAVIDZE, N RAMATY, R AF MANDZHAVIDZE, N RAMATY, R TI HIGH-ENERGY GAMMA-RAY EMISSION FROM PION DECAY IN A SOLAR-FLARE MAGNETIC LOOP SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; SUN FLARES; SUN PARTICLE EMISSION; SUN X-RAYS, GAMMA-RAYS ID LIMB-BRIGHTENING OBSERVATIONS; 1982 JUNE 3; PARTICLE-ACCELERATION; NEUTRAL RADIATION; BREMSSTRAHLUNG; ENVIRONMENT; GENERATION; ORIGIN AB We have investigated the production of high-energy gamma rays resulting from pion decay in a solar flare magnetic loop. We took into account magnetic mirroring, MHD pitch-angle scattering, and all of the relevant loss processes and photon production mechanisms. We treated the transport of both the primary ions and the secondary positrons resulting from the decay of the positive pions, as well as the transport of the produced gamma-ray emission. We calculated the distributions of the gamma rays as a function of atmospheric depth, time, emission angle, and photon energy and studied the dependence of these distributions on the model parameters. The obtained angular distributions are not sufficiently anisotropic to account for the observed limb brightening of the greater than 10 MeV flare emission, indicating that the bulk of this emission is bremsstrahlung from primary electrons. We compared our calculations with the available data for pion decay radiation from the 1982 June 3 flare and considered the possible models of particle transport and gamma-ray production for this flare. C1 GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP MANDZHAVIDZE, N (reprint author), ACAD SCI GESSR,INST GEOPHYS,TBILISI 380093,GEORGIA,USSR. NR 46 TC 45 Z9 46 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1992 VL 389 IS 2 BP 739 EP 755 DI 10.1086/171247 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HP119 UT WOS:A1992HP11900026 ER PT J AU DAVILA, JM THOMPSON, WT AF DAVILA, JM THOMPSON, WT TI A ROTATING TOMOGRAPHIC IMAGER FOR SOLAR EXTREME-ULTRAVIOLET SOFT-X-RAY EMISSION SO ASTROPHYSICAL JOURNAL LA English DT Article DE INSTRUMENTATION, DETECTORS; SUN, UV RADIATION; SUN, X-RAYS, GAMMA-RAYS AB We present a concept for a high-resolution EUV/soft X-ray imager that has much in common with the medical imaging procedure of tomography. The resulting instrument is compatible with a simpler, less costly spin-axis-stabilized spacecraft. To demonstrate the fidelity of the reconstruction procedure, we simulate the observation and reconstruction process and compare the results with the original image. C1 APPL RES CORP,LANDOVER,MD 20785. RP DAVILA, JM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Thompson, William/D-7376-2012 NR 2 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1992 VL 389 IS 2 BP L91 EP & DI 10.1086/186356 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HP121 UT WOS:A1992HP12100013 ER PT J AU RINSLAND, CP ZANDER, R MAHIEU, E DEMOULIN, P GOLDMAN, A EHHALT, DH RUDOLPH, J AF RINSLAND, CP ZANDER, R MAHIEU, E DEMOULIN, P GOLDMAN, A EHHALT, DH RUDOLPH, J TI GROUND-BASED INFRARED MEASUREMENTS OF CARBONYL SULFIDE TOTAL COLUMN ABUNDANCES - LONG-TERM TRENDS AND VARIABILITY SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SECULAR INCREASE; ATMOSPHERIC OCS; SOLAR SPECTRA; TROPOSPHERE; CONSTITUENTS; INTENSITIES; CHEMISTRY; DISULFIDE; METHANE; LAYER AB Total vertical column abundances of carbonyl sulfide (OCS) have been derived from time series of high-resolution infrared solar absorption spectra recorded at the National Solar Observatory McMath solar telescope facility on Kitt Peak (altitude 2.09 km, latitude 31.9-degrees-N, longitude 111.6-degrees-W), southwest of Tucson, Arizona, and at the International Scientific Station of the Jungfraujoch (altitude 3.58 km, latitude 46.5-degrees-N, longitude 8.0-degrees-E), in the Swiss Alps. The analysis of both data sets is based on nonlinear least squares spectral fittings of narrow intervals centered on lines of the intense nu-3 band of OCS, the P(37) transition at 2045.5788 cm-1 and the P(15) transition at 2055.8609 cm-1, with a consistent set of spectroscopic line parameters. The Kitt Peak measurements, recorded on 30 different days between May 1977 and March 1991, show a 10% peak-to-peak seasonal cycle with a summer maximum and a winter minimum and a trend in the total column abundance equal to (0.1 +/- 0.2)% yr-1, 2-sigma. Jungfraujoch solar spectra recorded on 67 different days between October 1984 and April 1991 have been analyzed. The fitted trend in the Jungfraujoch total columns, (-0.1 +/- 0.5)% yr-1, 2-sigma, is consistent with the Kitt Peak trend results within the errors. The Jungfraujoch total columns show a more complex seasonal variation than noted in the Kitt Peak data. The mean of the daily averaged total columns, 8.44 x 10(15) molecules cm-2 above Kitt Peak and 6.41 x 10(15) molecules cm-2 above the Jungfraujoch station, correspond respectively to mean tropospheric mixing ratios of 0.54 +/- 0.04 and 0.52 +/- 0.04 parts per billion by volume; these values are consistent with previously reported remote and in situ measurements. Taken together, the results from the two sites indicate that there has been no significant change in the OCS total column abundance at northern mid-latitudes over the last decade. C1 UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE COINTE, BELGIUM. FORSCHUNGSZENTRUM JULICH, FORSCHUNGSZENTRUM, INST ATMOSPHAR CHEM, W-5170 JULICH 1, GERMANY. UNIV DENVER, DEPT PHYS, DENVER, CO 80208 USA. RP RINSLAND, CP (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NR 45 TC 32 Z9 32 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 20 PY 1992 VL 97 IS D5 BP 5995 EP 6002 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA HQ644 UT WOS:A1992HQ64400017 ER PT J AU KINTNER, PM VAGO, J CHESNEY, S ARNOLDY, RL LYNCH, KA POLLOCK, CJ MOORE, TE AF KINTNER, PM VAGO, J CHESNEY, S ARNOLDY, RL LYNCH, KA POLLOCK, CJ MOORE, TE TI LOCALIZED LOWER HYBRID ACCELERATION OF IONOSPHERIC PLASMA SO PHYSICAL REVIEW LETTERS LA English DT Article ID SUPRAURORAL REGION; ION-ACCELERATION; WAVES AB We report observations of the transverse acceleration of ions in localized regions of intense lower hybrid waves at altitudes near 1000 km in the auroral ionosphere. The acceleration regions are thin filaments with dimensions across geomagnetic field lines of about 50-100 m corresponding to 5-10 thermal ion gyroradii or one hot ion gyroradius. Within the acceleration region lower hybrid waves reach peak-to-peak amplitudes of 100-300 mV/m and ions are accelerated transversely with characteristic energies of the order of 10 eV. These observations are consistent with theories of lower hybrid wave collapse. C1 UNIV NEW HAMPSHIRE,DURHAM,NH 03824. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP KINTNER, PM (reprint author), CORNELL UNIV,ITHACA,NY 14853, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 14 TC 138 Z9 138 U1 0 U2 1 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 APR 20 PY 1992 VL 68 IS 16 BP 2448 EP 2451 DI 10.1103/PhysRevLett.68.2448 PG 4 WC Physics, Multidisciplinary SC Physics GA HP801 UT WOS:A1992HP80100011 ER PT J AU SHIVAKUMAR, KN BIGELOW, CA NEWMAN, JC AF SHIVAKUMAR, KN BIGELOW, CA NEWMAN, JC TI PARALLEL COMPUTATION IN A 3-DIMENSIONAL ELASTIC PLASTIC FINITE-ELEMENT ANALYSIS SO COMPUTERS & STRUCTURES LA English DT Article AB A CRAY parallel processing technique called autotasking was implemented in a three-dimensional, elastic-plastic, finite-element code. The technique was evaluated on two CRAY supercomputers, a CRAY 2 and a CRAY Y-MP. Autotasking was implemented in all major portions of the code, except the matrix equations solver. Compiler directives alone were not able to properly multitask the code; user-inserted directives were required to achieve better performance. It was noted that the connect time, rather than wall-clock time, was more appropriate to determine speedup in multiuser environments. For a typical example problem, a speedup of 2.1 (1.8 when the solution time was included) was achieved in a dedicated environment and 1.7 (1.6 with solution time) in a multiuser environment on a four-processor CRAY 2 supercomputer. The speedup on a three-processor CRAY Y-MP was about 2.4 (2.0 with solution time) in a multiuser environment. The superior performance of the CRAY Y-MP compared to the CRAY 2 in the multiuser environment may be due to the difference in architecture and the low load on the CRAY Y-MP. The speedups achieved are quite good considering the minimal effort required to implement autotasking in this application code. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP SHIVAKUMAR, KN (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23666, USA. NR 17 TC 3 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7949 J9 COMPUT STRUCT JI Comput. Struct. PD APR 17 PY 1992 VL 43 IS 2 BP 237 EP 245 DI 10.1016/0045-7949(92)90140-U PG 9 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA HW846 UT WOS:A1992HW84600003 ER PT J AU ABRAMOVICI, A ALTHOUSE, WE DREVER, RWP GURSEL, Y KAWAMURA, S RAAB, FJ SHOEMAKER, D SIEVERS, L SPERO, RE THORNE, KS VOGT, RE WEISS, R WHITCOMB, SE ZUCKER, ME AF ABRAMOVICI, A ALTHOUSE, WE DREVER, RWP GURSEL, Y KAWAMURA, S RAAB, FJ SHOEMAKER, D SIEVERS, L SPERO, RE THORNE, KS VOGT, RE WEISS, R WHITCOMB, SE ZUCKER, ME TI LIGO - THE LASER-INTERFEROMETER-GRAVITATIONAL-WAVE-OBSERVATORY SO SCIENCE LA English DT Article ID RELATIVISTIC GRAVITY; BLACK-HOLES; OSCILLATIONS; DETECTORS; RADIATION AB The goal of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Project is to detect and study astrophysical gravitational waves and use data from them for research in physics and astronomy. LIGO will support studies concerning the nature and nonlinear dynamics of gravity, the structures of black holes, and the equation of state of nuclear matter. It will also measure the masses, birth rates, collisions, and distributions of black holes and neutron stars in the universe and probe the cores of supernovae and the very early universe. The technology for LIGO has been developed during the past 20 years. Construction will begin in 1992, and under the present schedule, LIGO's gravitational-wave searches will begin in 1998. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. MIT, CAMBRIDGE, MA 02139 USA. RP CALTECH, PASADENA, CA 91125 USA. RI Raab, Frederick/E-2222-2011 NR 56 TC 1480 Z9 1492 U1 51 U2 156 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 EI 1095-9203 J9 SCIENCE JI Science PD APR 17 PY 1992 VL 256 IS 5055 BP 325 EP 333 DI 10.1126/science.256.5055.325 PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HP032 UT WOS:A1992HP03200025 PM 17743108 ER PT J AU STOLARSKI, R BOJKOV, R BISHOP, L ZEREFOS, C STAEHELIN, J ZAWODNY, J AF STOLARSKI, R BOJKOV, R BISHOP, L ZEREFOS, C STAEHELIN, J ZAWODNY, J TI MEASURED TRENDS IN STRATOSPHERIC OZONE SO SCIENCE LA English DT Article ID ANTARCTIC OZONE; SAGE-II; NORTHERN-HEMISPHERE; MCMURDO STATION; HOLE; PROFILE; TOMS AB Recent findings, based on both ground-based and satellite measurements, have established that there has been an apparent downward trend in the total column amount of ozone over mid-latitude areas of the Northern Hemisphere in all seasons. Measurements of the altitude profile of the change in the ozone concentration have established that decreases are taking place in the lower stratosphere in the region of highest ozone concentration. Analysis of updated ozone records, through March of 1991, including 29 stations in the former Soviet Union, and analysis of independently calibrated satellite data records from the Total Ozone Mapping Spectrometer and Stratospheric Aerosol and Gas Experiment instruments confirm many of the findings originally derived from the Dobson record concerning northern mid-latitude changes in ozone. The data from many instruments now provide a fairly consistent picture of the change that has occurred in stratospheric ozone levels. C1 WORLD METEOROL ORG,CH-1211 GENEVA 20,SWITZERLAND. UNIV THESSALONIKI,GR-54006 SALONIKA,GREECE. ALLIED SIGNAL CORP,BUFFALO,NY 14210. SWISS FED INST TECHNOL,ATMOSPHER PHYS LAB,CH-8093 ZURICH,SWITZERLAND. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP STOLARSKI, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Stolarski, Richard/B-8499-2013 OI Stolarski, Richard/0000-0001-8722-4012 NR 43 TC 399 Z9 417 U1 1 U2 22 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 17 PY 1992 VL 256 IS 5055 BP 342 EP 349 DI 10.1126/science.256.5055.342 PG 8 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HP032 UT WOS:A1992HP03200027 PM 17743110 ER PT J AU BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR AF BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR TI THEORETICAL-STUDY OF TRANSITION-METAL IONS BOUND TO BENZENE SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; GAS-PHASE; ELECTRON CORRELATION; POSITIVE-IONS; CONTRACTION; ORBITALS; PHOTODISSOCIATION AB Theoretical binding energies are reported for all first-row and selected second-row transition metal ions (M+) bound to benzene. The calculations employ basis sets of at least double-zeta plus polarization quality and account for electron correlation using the modified coupled-pair functional method. While the bonding is predominantly electrostatic, the binding energies are significantly increased by electron correlation, because the donation from the metal d orbitals to the benzene pi* orbitals is not well described at the self-consistent-field level. The uncertainties in the computed binding energies are estimated to be about 5 kcal/mol. Although the calculated and experimental binding energies generally agree to within their combined uncertainties, it is likely that the true binding energies lie in the lower portion of the experimental range. This is supported by the very good agreement between the theoretical and recent experimental binding energies for AgC6H6+. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 35 TC 202 Z9 203 U1 0 U2 7 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD APR 16 PY 1992 VL 96 IS 8 BP 3273 EP 3278 DI 10.1021/j100187a018 PG 6 WC Chemistry, Physical SC Chemistry GA HQ013 UT WOS:A1992HQ01300018 ER PT J AU JIANG, BN AF JIANG, BN TI A LEAST-SQUARES FINITE-ELEMENT METHOD FOR INCOMPRESSIBLE NAVIER-STOKES PROBLEMS SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE FINITE ELEMENT; LEAST SQUARES; NAVIER-STOKES EQUATIONS; 1ST-ORDER SYSTEM; VELOCITY PRESSURE VORTICITY; EQUAL-ORDER INTERPOLATIONS ID VELOCITY-PRESSURE FORMULATION; EQUATIONS; FLOWS AB A least-squares finite element method based on the velocity-pressure-vorticity formulation was proposed for solving steady incompressible Navier-Stokes problems. This method leads to a minimization problem rather than to the saddle point problem of the classic mixed method and can thus accommodate equal-order interpolations. The method has no parameter to tune. The associated algebraic system is symmetric and positive definite. In order to show the validity of the method for high-Reynolds-number problems, this paper provides numerical results for cavity flow at Reynolds number up to 10000 and backward-facing step flow at Reynolds number up to 900. C1 NASA, LEWIS RES CTR, INST COMPUTAT MECH PROPULS, CLEVELAND, OH 44135 USA. NR 36 TC 65 Z9 66 U1 0 U2 1 PU WILEY-BLACKWELL PI HOBOKEN PA 111 RIVER ST, HOBOKEN 07030-5774, NJ USA SN 0271-2091 EI 1097-0363 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD APR 15 PY 1992 VL 14 IS 7 BP 843 EP 859 DI 10.1002/fld.1650140706 PG 17 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA HN435 UT WOS:A1992HN43500005 ER PT J AU GHOSN, LJ KANTZOS, P TELESMAN, J AF GHOSN, LJ KANTZOS, P TELESMAN, J TI MODELING OF CRACK BRIDGING IN A UNIDIRECTIONAL METAL MATRIX COMPOSITE SO INTERNATIONAL JOURNAL OF FRACTURE LA English DT Article ID FIBER; MECHANICS; FRACTURE AB The effective fatigue crack driving force and crack opening profiles were determined analytically for fatigue tested unidirectional composite specimens exhibiting fiber bridging. The crack closure pressure due to bridging was modeled using two approaches; the fiber pressure model and the shear lag model. For both closure models, the Bueckner weight function method and the finite element method were used to calculate crack opening displacements and the crack driving force. The predicted near crack tip opening profile agreed well with the experimentally measured profiles for single edge notch SCS-6/Ti-15-3 metal matrix composite specimens. The numerically determined effective crack driving force, DELTA-K(eff), was calculated using both models to correlate the measured crack growth rate in the composite. The calculated DELTA-K(eff) from both models accounted for the crack bridging by showing a good agreement between the measured fatigue crack growth rates of the bridged composite and that of unreinforced, unbridged titanium matrix alloy specimens. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP GHOSN, LJ (reprint author), SVERDRUP TECHNOL INC,LEWIS RES CTR GRP,BROOK PK,OH 44142, USA. NR 18 TC 33 Z9 33 U1 0 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0376-9429 J9 INT J FRACTURE JI Int. J. Fract. PD APR 15 PY 1992 VL 54 IS 4 BP 345 EP 357 DI 10.1007/BF00035108 PG 13 WC Materials Science, Multidisciplinary; Mechanics SC Materials Science; Mechanics GA HX403 UT WOS:A1992HX40300004 ER PT J AU PARKINSON, CL AF PARKINSON, CL TI INTERANNUAL VARIABILITY OF MONTHLY SOUTHERN-OCEAN SEA ICE DISTRIBUTIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID MULTICHANNEL MICROWAVE RADIOMETER; WEDDELL POLYNYA; CARBON-DIOXIDE; EXTENT AB The region of the Southern Ocean exhibiting interannual variability in monthly averaged sea ice distributions has been mapped and analyzed using data from the Nimbus 5 Electrically Scanning Microwave Radiometer (ESMR) and the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR). Over the 13-year record from the two instruments (1973-1976 and late 1978 through mid-1987), interannual variability is particularly high for the early summer month of December, when 10 x 10(6) km2 of the ocean had ice-covered conditions in some years and ice-free conditions in other years. This area of December variability is almost three times the ocean area consistently having ice-covered conditions in the 13 ESMR/SMMR December. In contrast, in mid-winter the area of consistent ice coverage far exceeds the am of variability, which, in spits of the much greater ice coverage overall, is not as large as the area of variability in December. The mid-winter variability is confined to (1) a ring of variable width around the edge of the ice pack and (2) the location of the 1974-1976 Weddell polynya. Separation of the results to the ESMR and SMMR time periods shows that ice in the West Indian Ocean and the Ross Sea tended to be more expansive in the earlier, ESMR years than in the later. SMMR years. but that ice in the Weddell Sea tended to be less expansive in the ESMR years. In the Bellingshausen and Amundsen Seas, the ESMR years tended to have less summer ice than the SMMR years but not less winter ice. The images and plots provide a succinct summary of the range of spatial distributions of Southern Ocean sea ice during the ESMR and SMMR time periods. They can hence be used as a convenient base for comparisons with future sea ice distributions in the effort to identify occurrences of climate change. RP PARKINSON, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,CODE 971,GREENBELT,MD 20771, USA. RI Parkinson, Claire/E-1747-2012 OI Parkinson, Claire/0000-0001-6730-4197 NR 27 TC 32 Z9 32 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD APR 15 PY 1992 VL 97 IS C4 BP 5349 EP 5363 DI 10.1029/92JC00153 PG 15 WC Oceanography SC Oceanography GA HQ256 UT WOS:A1992HQ25600015 ER PT J AU FULLER, GM SCHRAMM, DN AF FULLER, GM SCHRAMM, DN TI LATE-PHASE-TRANSITION-INDUCED FLUCTUATIONS IN THE COSMIC NEUTRINO DISTRIBUTION AND THE FORMATION OF STRUCTURE IN THE UNIVERSE SO PHYSICAL REVIEW D LA English DT Article ID BROKEN LEPTON NUMBER; SOLAR NEUTRINOS; FALSE VACUUM; MATTER; OSCILLATIONS; GENERATION; GALAXIES; SCALE AB We show that late-time (T(c) less-than-or-equal-to 1 eV) cosmic vacuum phase transitions which induce separation of phases and which involve a discontinuity in neutrino properties (e.g., mass) across phase boundaries could give rise to spatial inhomogeneities in the distribution of neutrinos. The nucleation physics of the phase transition would determine the spatial scale of the fluctuations. These density perturbations would be born in the nonlinear regime and could have masses in the range of 10(6)M.-10(13)M.. If the fluctuations are shells, as expected, and there is gravitational modification of the original phase-transition nucleation scale then the upper limit on their masses could be considerably larger (almost-equal-to 10(18)M.), possibly encompassing the largest structures in the Universe. The motivation for this work stems, in part, from the possibility that future experiments (i.e., solar neutrino experiments) may suggest new, low-energy-scale weak-interaction phenomena, such as neutrino flavor mixing. C1 UNIV CHICAGO,DEPT PHYS & ASTRON,CHICAGO,IL 60637. FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,DEPT ASTROPHYS,CHICAGO,IL 60637. RP FULLER, GM (reprint author), UNIV CALIF SAN DIEGO,DEPT PHYS,LA JOLLA,CA 92093, USA. NR 51 TC 16 Z9 16 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 1992 VL 45 IS 8 BP 2595 EP 2600 DI 10.1103/PhysRevD.45.2595 PG 6 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA HP205 UT WOS:A1992HP20500004 ER PT J AU FRIEMAN, JA JAFFE, AH AF FRIEMAN, JA JAFFE, AH TI COSMOLOGICAL CONSTRAINTS ON PSEUDO NAMBU-GOLDSTONE BOSONS SO PHYSICAL REVIEW D LA English DT Article ID SUPERSTRING MODELS; INVISIBLE AXIONS; COSMIC STRINGS; EARLY-UNIVERSE; DOMAIN-WALLS; EVOLUTION; SN-1987A; TEXTURE AB Particle-physics models with pseudo Nambu-Goldstone bosons (PNGB's) are characterized by two mass scales: a global spontaneous-symmetry-breaking scale f and a soft (explicit) symmetry-breaking scale LAMBDA. We investigate general model-insensitive constraints on this two-dimensional parameter space arising from the cosmological and astrophysical effects of PNGB's. In particular, we study constraints arising from vacuum misalignment and thermal production of PNGB's, topological defects, and the cosmological effects of PNGB decay products, as well as astrophysical constraints from stellar PNGB emission. Bounds on the Peccei-Quinn axion scale, 10(10) GeV less-than-or-similar-to f(PQ) less-than-or-similar-to 10(10)-10(12) GeV, emerge as a special case, where the soft breaking scale is fixed at LAMBDA(QCD) congruent-to 100 MeV. C1 UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP FRIEMAN, JA (reprint author), FERMI NATL ACCELERATOR LAB,FERMILAB ASTROPHYS CTR,NASA,BATAVIA,IL 60510, USA. RI Jaffe, Andrew/D-3526-2009 NR 45 TC 14 Z9 14 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 1992 VL 45 IS 8 BP 2674 EP 2684 DI 10.1103/PhysRevD.45.2674 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA HP205 UT WOS:A1992HP20500013 ER PT J AU LEE, KY NAIR, VP WEINBERG, EJ AF LEE, KY NAIR, VP WEINBERG, EJ TI BLACK-HOLES IN MAGNETIC MONOPOLES SO PHYSICAL REVIEW D LA English DT Article ID ZERO-ORDER STRUCTURE; MILLS-HIGGS SYSTEM; WORMHOLE SOLUTIONS AB We study magnetically charged classical solutions of a spontaneously broken gauge theory interacting with gravity. We show that nonsingular monopole solutions exist only if the Higgs-field vacuum expectation value v is less than or equal to a critical value v(cr), which is of the order of the Planck mass. In the limiting case, the monopole becomes a black hole, with the region outside the horizon described by the critical Reissner-Nordstrom solution. For v < v(cr), we find additional solutions which are singular at r = 0, but which have this singularity hidden within a horizon. These have nontrivial matter fields outside the horizon, and may be interpreted as small black holes lying within a magnetic monopole. The nature of these solutions as a function of v and of the total mass M and their relation to the Reissner-Nordstrom solutions are discussed. C1 FERMI NATL ACCELERATOR LAB,THEORY GRP,BATAVIA,IL 60510. FERMI NATL ACCELERATOR LAB,FERMILAB ASTROPHYS CTR,NASA,BATAVIA,IL 60510. RP LEE, KY (reprint author), COLUMBIA UNIV,DEPT PHYS,NEW YORK,NY 10027, USA. RI Lee, Kimyeong/K-1070-2013 OI Lee, Kimyeong/0000-0003-3451-1514 NR 18 TC 155 Z9 155 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 APR 15 PY 1992 VL 45 IS 8 BP 2751 EP 2761 DI 10.1103/PhysRevD.45.2751 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA HP205 UT WOS:A1992HP20500020 ER PT J AU DOWKER, F GREGORY, R TRASCHEN, J AF DOWKER, F GREGORY, R TRASCHEN, J TI EUCLIDEAN BLACK-HOLE VORTICES SO PHYSICAL REVIEW D LA English DT Article ID COSMIC STRINGS; BARYON NUMBER; STABILITY; FIELD AB We argue the existence of solutions of the Euclidean Einstein equations that correspond to a vortex sitting at the horizon of a black hole. We find the asymptotic behaviors, at the horizon and at infinity, of vortex solutions for the gauge and scalar fields in an Abelian Higgs model on a Euclidean Schwarzschild background and interpolate between them by integrating the equations numerically. Calculating the back reaction shows that the effect of the vortex is to cut a slice out of the Euclidean Schwarzschild geometry. The consequences of these solutions for black-hole thermodynamics are discussed. C1 UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. UNIV MASSACHUSETTS,DEPT PHYS,AMHERST,MA 01002. RP DOWKER, F (reprint author), FERMI NATL ACCELERATOR LAB,FERMILAB ASTROPHYS CTR,NASA,POB 500,BATAVIA,IL 60510, USA. NR 25 TC 40 Z9 40 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 1992 VL 45 IS 8 BP 2762 EP 2771 DI 10.1103/PhysRevD.45.2762 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA HP205 UT WOS:A1992HP20500021 ER PT J AU CHOI, SR TIKARE, V AF CHOI, SR TIKARE, V TI CRACK HEALING BEHAVIOR OF HOT-PRESSED SILICON-NITRIDE DUE TO OXIDATION SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID STRENGTH; SI3N4 C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHOI, SR (reprint author), CLEVELAND STATE UNIV,CLEVELAND,OH 44115, USA. NR 17 TC 84 Z9 88 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD APR 15 PY 1992 VL 26 IS 8 BP 1263 EP 1268 DI 10.1016/0956-716X(92)90574-X PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA HM802 UT WOS:A1992HM80200020 ER PT J AU BOZZOLO, G FERRANTE, J AF BOZZOLO, G FERRANTE, J TI LATTICE-PARAMETERS OF FCC BINARY-ALLOYS USING A NEW SEMIEMPIRICAL METHOD SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID EMBEDDED-ATOM-METHOD; ELECTRONIC THEORY; PHASE-STABILITY; METAL ALLOYS; CU-AU; AG-AU; PD; NI C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BOZZOLO, G (reprint author), ANALEX CORP,3001 AEROSP PKWY,BROOK PK,OH 44142, USA. NR 16 TC 8 Z9 8 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD APR 15 PY 1992 VL 26 IS 8 BP 1275 EP 1280 DI 10.1016/0956-716X(92)90576-Z PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA HM802 UT WOS:A1992HM80200022 ER PT J AU KUSSMAUL, M MIRTICH, MJ CURREN, A AF KUSSMAUL, M MIRTICH, MJ CURREN, A TI ION-BEAM TREATMENT OF POTENTIAL SPACE MATERIALS AT THE NASA LEWIS RESEARCH-CENTER SO SURFACE & COATINGS TECHNOLOGY LA English DT Article; Proceedings Paper CT 7TH INTERNATIONAL CONF ON SURFACE MODIFICATION OF METALS BY ION BEAMS ( SMMIB-91 ) CY JUL 14-19, 1991 CL GEORGETOWN UNIV, WASHINGTON, DC SP USN, OFF NAVAL RES, USA, RES OFF, ANATECH, COMMONWEALTH SCI, IMPLANT SCI, NISSIN ELECT, PEABODY SCI, SPIRE, ULTRA HIGH VACUUM INSTRUMENTS HO GEORGETOWN UNIV AB Ion source systems, in different configurations, have been used to generate unique surface morphologies for several NASA space applications. The discharge chamber of a 30 cm ion source was successfully used to texture potential space radiator materials for the purpose of obtaining values of thermal emittance greater than 0.85 at 700 and 900 K. High absorptance surfaces were obtained using ion beam seed-texturing, for space radiator materials that were flown on the long duration exposure facility (LDEF) for 5.8 years in space. An ion source discharge chamber was also used to develop electrode surfaces with suppressed secondary electron emission characteristics for use in collectors in microwave amplifier traveling wave tubes. This was accomplished by sputtering textured carbon onto copper as well as texturing copper using tantalum and molybdenum as sacrificial texture-inducing seeding materials. In a third configuration, a dual-ion-beam system was used to generate high transmittance diamond-like carbon (DLC) films. C1 NASA,CLEVELAND,OH 44135. RP KUSSMAUL, M (reprint author), SVERDRUP TECHNOL INC,BROOK PK,OH 44142, USA. NR 14 TC 5 Z9 5 U1 1 U2 3 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0257-8972 J9 SURF COAT TECH JI Surf. Coat. Technol. PD APR 15 PY 1992 VL 51 IS 1-3 BP 299 EP 306 DI 10.1016/0257-8972(92)90254-8 PG 8 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA HV289 UT WOS:A1992HV28900051 ER PT J AU JAMES, GK AJELLO, JM KANIK, I FRANKLIN, B SHEMANSKY, DE AF JAMES, GK AJELLO, JM KANIK, I FRANKLIN, B SHEMANSKY, DE TI THE EXTREME ULTRAVIOLET EMISSION-SPECTRUM OF CO PRODUCED BY ELECTRON-IMPACT AT 20 AND 200 EV SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID DENSE INTERSTELLAR CLOUDS; CROSS-SECTIONS; OSCILLATOR-STRENGTHS; MEDIUM-RESOLUTION; CARBON-MONOXIDE; RYDBERG SERIES; DIPOLE-MOMENTS; 115 NM; PHOTODISSOCIATION; N-2 AB In this first part of a laboratory study of predissociation in CO we have measured the electron-impact-induced fluorescence spectrum of CO in the wavelength range 40-125 nm at a spectral resolution of 0.5 nm. The experiment was performed in a crossed-beam configuration under optically thin conditions. Our spectral measurements at 200 eV electron impact energy provide the emission cross sections of atomic dissociation fragments (C I, C II, O I, O II) and the vibrational transitions of the B (1)SIGMA+, C (1)SIGMA+, E (1)PI-X (1)SIGMA+ band systems of CO. The measured emission cross sections of these molecular transitions will be needed for comparison with excitation cross sections from electron energy-loss spectra to determine predissociation yields. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85712. RP JAMES, GK (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 42 TC 20 Z9 20 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD APR 14 PY 1992 VL 25 IS 7 BP 1481 EP 1496 DI 10.1088/0953-4075/25/7/019 PG 16 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA HQ156 UT WOS:A1992HQ15600020 ER PT J AU KETO, E BALL, R ARENS, J JERNIGAN, G MEIXNER, M AF KETO, E BALL, R ARENS, J JERNIGAN, G MEIXNER, M TI SUBARCSECOND MIDINFRARED IMAGING OF THE NUCLEI OF THE INFRARED BRIGHT GALAXIES NGC-1614 AND NGC-7469 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES INDIVIDUAL (NGC-1614, NGC-7469); GALAXIES NUCLEI; INFRARED GALAXIES; STARS FORMATION ID STAR FORMATION; APERTURE SYNTHESIS; GALACTIC NUCLEI; PHOTOMETRY; EMISSION; 10-MU-M AB We report on the first subarcsecond resolution mid-IR images of the nuclei of two galaxies from the IRAS bright sample, NGC 1614 and NGC 7469. Our results show that the starburst galaxy NGC 1614 contains a double structure in the nuclear region. Most of the flux, 78% of 650 +/- 50 mJy, is emitted in two unresolved regions of 0.6" FWHM (190 pc at 64 Mpc) of nearly equal strength separated by 0.6" (200 pc). Most of the remaining flux is derived from a small arm 1" in length (310 pc). The Seyfert I galaxy NGC 7469 shows an elongated structure, 1.4" x 0.7" (450 x 220 pc at 66 Mpc). C1 UNIV HAWAII,NASA,INFRARED TELESCOPE FACIL,HONOLULU,HI 96822. UNIV CALIF LAWRENCE LIVERMORE NATL LAB,INST GEOPHYS & PLANETARY PHYS,LIVERMORE,CA 94550. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94760. RP KETO, E (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. NR 23 TC 23 Z9 23 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1992 VL 389 IS 1 BP 223 EP 226 DI 10.1086/171199 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HM689 UT WOS:A1992HM68900016 ER PT J AU BROWN, LE AF BROWN, LE TI POSSIBLE SOURCES OF THE POPULATION-I LITHIUM ABUNDANCE AND LIGHT-ELEMENT EVOLUTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY ABUNDANCES; GALAXY EVOLUTION; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES ID GALACTIC CHEMICAL EVOLUTION; HADRON PHASE-TRANSITION; METAL-DEFICIENT DWARFS; SOLAR NEIGHBORHOOD; PRIMORDIAL LITHIUM; NEUTRON DIFFUSION; NUCLEOSYNTHESIS; GALAXY; STARS; ORIGIN AB We examine one-zone numerical models of Galactic chemical evolution of the light elements (lithium, beryllium, boron, and deuterium) with a broad sample of possible stellar lithium production sites and star formation histories (including the multiple merger model of Mathews & Schramm. We investigate primordial values of Li-7/H = 10(-8) or 10(-10). Scenarios starting with primordial Li-7/H approximately 10(-10) are well fitted by several of our models. We obtain the best agreement with observations for star formation histories with an overall decrease in the star formation rate with time. Models with high primordial lithium are constrained by observations of lithium and potassium in the interstellar medium of the Large Magellanic Cloud (LMC) to have initial Li abundances close to the Population I value of approximately 10(-9). Li-7 production in intermediate- or high-mass stars (m > 4 M.) is found to fit observations somewhat better than production in low-mass (1 - 5 M.) stars. Since elevated levels of lithium are commonly observed in intermediate-mass stars in the LMC, it seems likely that this is indeed the major source of the Population I Li-7 abundance. The current predictions for low-level yields of Li-7 from supernova envelope shocks do not change these conclusions. C1 UNIV CHICAGO,CHICAGO,IL 60637. FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. NR 71 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1992 VL 389 IS 1 BP 251 EP 268 DI 10.1086/171202 PN 1 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HM689 UT WOS:A1992HM68900019 ER PT J AU JUSTTANONT, K TIELENS, AGGM AF JUSTTANONT, K TIELENS, AGGM TI MASS-LOSS FROM OH/IR STARS - MODELS FOR THE INFRARED-EMISSION OF CIRCUMSTELLAR DUST SHELLS SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; RADIATION MECHANISMS THERMAL; STARS GIANT; STARS MASS-LOSS ID OH-IR STARS; LOSS RATES; EVOLVED STARS; SKY SURVEY; 1612 MHZ; RADIO; EVOLUTION; GRAINS; GIANTS; ABSORPTION AB We have modeled the infrared emission of a sample of 24 OH/IR stars deriving the properties of circumstellar dust and mass-loss rate of the central star. Our results show that for some sources the observations of the far-infrared emission is well fitted with a lambda--1 law, while some have a steeper index of 1.5. At 60-mu-m, this corresponds to kappa-60 of 240 and 160 cm2 g-1 for the former and latter, respectively. For a few sources, detailed studies of the observed 10-mu-m feature suggest the presence of circumstellar ice grains. Dust mass-loss rates have been determined from detailed studies for all the stars in this sample. They range from 6.0 x 10(-10) M. yr-1 for an optically visible Mira to 2.2 x 10(-6) M. yr-1 for a heavily obscured OH/IR star. These dust mass-loss rates are then compared to those calculated from IRAS photometry using 12, 25, and 60-mu-m fluxes. The dust mass-loss rates are also compared to gas mass-loss rates determined from OH and CO observations. For stars with tenuous shells, a dust-to-gas ratio of 0.001 is obtained. For heavily obscured stars, however, both OH and CO seem to underestimate the mass-loss rate considerably. This may be due to a recent (< 10(2) yr) enhancement in mass-loss rates. C1 UNIV LONDON UNIV COLL,DEPT PHYS & ASTRON,LONDON WC1E 6BT,ENGLAND. RP JUSTTANONT, K (reprint author), NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035, USA. OI /0000-0003-1689-9201 NR 63 TC 73 Z9 74 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1992 VL 389 IS 1 BP 400 EP 412 DI 10.1086/171215 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HM689 UT WOS:A1992HM68900032 ER PT J AU KEENAN, FP FEIBELMAN, WA BERRINGTON, KA AF KEENAN, FP FEIBELMAN, WA BERRINGTON, KA TI IMPROVED CALCULATIONS FOR THE C-III LAMBDA-LAMBDA-1907,1909 AND SI-III LAMBDA-LAMBDA-1883,1892 ELECTRON-DENSITY SENSITIVE EMISSION-LINE RATIOS, AND A COMPARISON WITH IUE OBSERVATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC DATA; BINARIES SYMBIOTIC; PLANETARY NEBULAE GENERAL; ULTRAVIOLET STARS ID BERYLLIUM ISOELECTRONIC SEQUENCE; PLANETARY-NEBULAE; OSCILLATOR-STRENGTHS; TEMPERATURES; TRANSITIONS; EXCITATION; PROGRAM; SUN AB Theoretical electron density sensitive emission-line ratios are presented for R1 = F(2s21S-2s2p3P32)/F(2s21S-2s2p3P1) = F(1907 angstrom)/F(1909 angstrom) in C III and R2 = F(3s21S-3s3p3P2)/F(3s21S-3s3p3P1) = F(1883 angstrom)/F(1892 angstrom) in Si III. These are significantly different from those deduced by previous authors, principally due to the adoption of improved electron excitation rates (for C III) and A-values (for Si III) in the present analysis. The observed values of R1 and R2 for several planetary nebulae and a symbiotic star, measured from high-resolution spectra obtained with the International Ultraviolet Explorer (IUE) satellite, lead to electron densities that are compatible, and are also in good agreement with those deduced from line ratios in other species. This provides observational support for the accuracy of the atomic data adopted in the present calculations. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. QUEENS UNIV BELFAST,DEPT APPL MATH & THEORET PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. RP KEENAN, FP (reprint author), QUEENS UNIV BELFAST,DEPT PURE & APPL PHYS,BELFAST BT7 1NN,ANTRIM,NORTH IRELAND. NR 29 TC 71 Z9 71 U1 0 U2 7 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1992 VL 389 IS 1 BP 443 EP 446 DI 10.1086/171220 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HM689 UT WOS:A1992HM68900037 ER PT J AU MAIER, E TWIGG, L SOFIA, S AF MAIER, E TWIGG, L SOFIA, S TI PRELIMINARY-RESULTS OF A BALLOON FLIGHT OF THE SOLAR DISK SEXTANT SO ASTROPHYSICAL JOURNAL LA English DT Article DE ARTIFICIAL SATELLITES, SPACE PROBES; SUN GENERAL AB This paper reports preliminary results of a balloon flight on 1990 October 11 of the solar disk sextant (SDS) experiment. The SDS is an instrument which measures the solar diameter at different orientations with respect to the solar polar axis. The flight, which lasted 9.5 hr, yielded useful data for approximately 6 hr, which included 26 full rotations of the instrument about its axis in addition to three 20 minute periods at fixed angles. For the two fixed angle data sets reduced, the probable error is of the order of 15 mas per 13 ms measurement, with a small systematic change from one set to the next. Fitting straight lines through these data sets with time as the independent variable yields slopes of (7.1 +/- 1.5) x 10(-3) and (6.7 +/- 1.6) x 10(-3) mas s-1, consistent with the value of 6.47 x 10(-3) mas s-1 expected from the Earth's approach to the Sun due to the orbital motion toward perihelion. Upon rotating the instrument on its axis a sinusoidal component of the diameter measurements was observed in each rotation cycle, with a (variable) amplitude of approximately 150 mas. This variation, which we think is due to inadequacies of the wedge holder to keep the objective wedge flats at a constant angle for all telescope orientations, greatly complicates the determination of the solar oblateness for the present instrument configuration, resulting in a relatively large error. The present result is epsilon = (5.6 +/- 6.3) x 10(-6), approximately 30-degrees offset from the polar-equator position. The absolute diameter obtained by means of the FFT definition is found to be 1919.269" +/- 0.240" or 1919.1.31" +/- 0.240", depending on the orientation mode of the measurement. C1 APPL RES CORP,LANDOVER,MD 20785. YALE UNIV,CTR SOLAR & SPACE RES,NEW HAVEN,CT 06511. RP MAIER, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 9102,GREENBELT,MD 20771, USA. NR 12 TC 26 Z9 27 U1 2 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1992 VL 389 IS 1 BP 447 EP 452 DI 10.1086/171221 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HM689 UT WOS:A1992HM68900038 ER PT J AU DWEK, E MOSELEY, SH GLACCUM, W GRAHAM, JR LOEWENSTEIN, RF SILVERBERG, RF SMITH, RK AF DWEK, E MOSELEY, SH GLACCUM, W GRAHAM, JR LOEWENSTEIN, RF SILVERBERG, RF SMITH, RK TI DUST AND GAS CONTRIBUTIONS TO THE ENERGY OUTPUT OF SN-1987A ON DAY 1153 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, OBSERVATIONS; INFRARED, GENERAL; NUCLEOSYNTHESIS; SUPERNOVAE, INDIVIDUAL (SN-1987A) ID SUPERNOVA 1987A; EMISSION; EJECTA AB We present 16-30-mu-m spectra of SN 1987A taken with the Kuiper Airborne Observatory on 1990 April 20 and 22, days 1152 and 1154 after core collapse. The spectrum is characterized by a flat continuum of 0.62 +/- 0.65 Jy, and a strong line at approximately 26-mu-m which we attribute to the [Fe II] 25.98-mu-m transition. The observations are used to derive the mass of radiating Fe II in the ejecta, the mass and temperature of the dust that gives rise to the continuum emission, and combined with optical and near infrared observations, the total bolometric luminosity of the supernova. The latter quantity constrains the contribution of the radioactive elements Co-57 and Ti-44 to the late-time energy output from the supernova. Specifically, we find that the observed luminosity requires that the Co-57/Co-56 mass production rate be enhanced by a factor of (4.5 +/- 1.6) compared to its solar value, if 10(-4) M. of Ti-44 were produced in the ejecta. Such overproduction could be inferred from observations of the 122 keV decay line of Co-57 with the OSSE instrument on board the Gamma Ray Observatory. However, this overproduction factor for Co-57 represents an upper limit, since other sources, including an infrared echo, may be contributing to the observed luminosity from the supernova. C1 APPL RES CORP,LANDOVER,MD 20785. UNIV CHICAGO,YERKES OBSERV,WILLIAMS BAY,WI 53191. CALTECH,DOWNS LAB,PASADENA,CA 91125. UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706. RP DWEK, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012 NR 33 TC 53 Z9 53 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1992 VL 389 IS 1 BP L21 EP L24 DI 10.1086/186339 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA HM690 UT WOS:A1992HM69000006 ER PT J AU WEITZ, CM FARR, TG AF WEITZ, CM FARR, TG TI EFFECTS OF SURFICIAL MODIFICATION PROCESSES ON THERMAL INFRARED SIGNATURES IN THE ARID SOUTHWESTERN UNITED-STATES SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID CIMA VOLCANIC FIELD; LANDSCAPE EVOLUTION; MOJAVE-DESERT; ROCK VARNISH; CALIFORNIA; CONTRAST; IMAGES AB Thermal infrared spectra from both laboratory and remote sensing instruments were used to distinguish different age lava flows with varying amounts of surficial modification at Cima and Lunar Crater volcanic fields. The modification processes affecting the lava flows cause spectral differences that can be seen in remotely sensed emittance spectra from the thermal infrared multispectral scanner. Important influences on the thermal infrared spectra include aeolian mantling, vegetation, lava flow roughness, and rock varnish. Laboratory thermal infrared reflectance spectra of the subaerially exposed surfaces of 1-15 cm basalt fragments at Cima volcanic field show a feature attributable to rock varnish on the younger flows (0.14-0.75 m.y.), that is lacking on the older flows (> 0.8 m.y.). This suggests that rock varnish is thinner on the older flows at Cima volcanic field. Scanning electron microscope images and thin sections of the different age flows at Cima volcanic field support the conclusion that rock varnish is thinner and may be eroding on the older flow surfaces. RP WEITZ, CM (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. OI Farr, Thomas/0000-0001-5406-2096 NR 23 TC 6 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD APR 10 PY 1992 VL 97 IS B4 BP 4649 EP 4665 DI 10.1029/91JB03154 PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA HQ336 UT WOS:A1992HQ33600022 ER PT J AU TAJIMA, F TRALLI, DM AF TAJIMA, F TRALLI, DM TI VARIATION OF SEISMIC SLIP IN THE GULF OF CALIFORNIA AND THE POSSIBLE EFFECT ON GEODETIC MEASUREMENTS OF PACIFIC-NORTH AMERICAN PLATE MOTION SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID GLOBAL POSITIONING SYSTEM; SOURCE MECHANISMS; HALF-SPACE; EARTHQUAKES; BASELINES; TECTONICS; LITHOSPHERE; PRECISION; BOUNDARY; ZONE AB The Gulf of California is a unique tectonic transition zone which progresses from an oceanic ridge-transform system at the mouth of the gulf to a predominantly continental transform system in southern California. Slip rates estimated from seismic moment data amount to about 17 to 30% of the accumulated tectonic slip in the gulf predicted by the NUVEL-1 plate motion model, even after accounting for the transition in crustal structure. The seismic to tectonic slip ratios also appear to increase slightly from south to north. This trend in the seismic moment release may reflect changes in the accommodation of Pacific-North American plate motion along the gulf which can be examined geodetically. On the other hand, geodetic measurements of the relative plate motion can be disturbed by short-term effects associated with episodic seismicity. To assess these effects, the surface displacements due to typical transform events in the gulf are estimated using a simple dislocation model. The results of this numerical calculation suggest that if a large transform event (M0 approximately 1.5 x 10(26) dyne cm) were to occur within 100 to 200 km of a geodetic baseline, for example one comprised in the GEOMEX Global Positioning System network across the southern gulf, the relative distance measurements could be affected by up to 15 mm. This is marginally at the error level of a few millimeters plus 2 parts in 10(8) of baseline length for GEOMEX measurements, which thus are sensitive only to the far-field displacement along the plate boundary (over baselines of a few hundred kilometers in length). C1 CALTECH, JET PROP LAB, DIV EARTH & SPACE SCI, PASADENA, CA 91702 USA. RP UNIV TEXAS, INST GEOPHYS, AUSTIN, TX 78759 USA. NR 40 TC 5 Z9 5 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD APR 10 PY 1992 VL 97 IS B4 BP 4903 EP 4913 DI 10.1029/91JB03011 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA HQ336 UT WOS:A1992HQ33600037 ER PT J AU MARSH, JG KOBLINSKY, CJ ZWALLY, HJ BRENNER, AC BECKLEY, BD AF MARSH, JG KOBLINSKY, CJ ZWALLY, HJ BRENNER, AC BECKLEY, BD TI A GLOBAL MEAN SEA-SURFACE BASED UPON GEOS 3 AND SEASAT ALTIMETER DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID SATELLITE ALTIMETRY; MODEL AB A mean sea surface relative to the International Union of Geodesy 1980 Geodetic Reference System reference ellipsoid has been derived from Seasat and GEOS 3 altimeter measurements. This surface, called MSS-9012, has been computed on a grid of 1/8-degrees resolution. Each elevation value was calculated by fitting all data within 111 km to a local biquadratic surface using Bayesian least squares. Individual data points were weighted inversely to the square of the distance to the grid location in the gridding process. The surface covers the global ocean between 70-degrees-N and 72-degrees-S. In the vicinity of sea ice the altimeter heights have been corrected for the on-board tracker error that occurs over non-Gaussian surfaces. Comparisons are made between MSS-9012 and ocean bathymetry. The eastern extent of the Chain Fracture Zone in the Gulf of Guinea is more apparent in the altimetry than in the bathymetry data, as are many other features. The combination of data from the two satellites has successfully retrieved more information about the sea surface than was previously possible using only Seasat data. C1 HUGHES STX,LANHAM,MD 20706. RP MARSH, JG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 971,GREENBELT,MD 20771, USA. NR 21 TC 5 Z9 7 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD APR 10 PY 1992 VL 97 IS B4 BP 4915 EP 4921 DI 10.1029/91JB03153 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA HQ336 UT WOS:A1992HQ33600038 ER PT J AU TSURUTANI, BT GONZALEZ, WD AF TSURUTANI, BT GONZALEZ, WD TI MAGNETIC STORM PREDICTIONS SO SCIENCE LA English DT Letter C1 INST NACL PESQUISAS ESPACIAIS,BR-12201 SAO JOSE CAMPOS,SP,BRAZIL. RP TSURUTANI, BT (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 1 TC 1 Z9 1 U1 1 U2 1 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 10 PY 1992 VL 256 IS 5054 BP 159 EP 159 DI 10.1126/science.256.5054.159 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HM896 UT WOS:A1992HM89600002 PM 17744704 ER PT J AU LYONS, JR YUNG, YL ALLEN, M AF LYONS, JR YUNG, YL ALLEN, M TI SOLAR CONTROL OF THE UPPER-ATMOSPHERE OF TRITON SO SCIENCE LA English DT Article ID IONOSPHERE; PHOTOCHEMISTRY; CHEMISTRY; NEPTUNE; METHANE; CARBON; TITAN; MODEL AB If the upper atmosphere and ionosphere of Triton are controlled by precipitation of electrons from Neptune's magnetosphere as previously proposed, Triton could have the only ionosphere in the solar system not controlled by solar radiation. However, a new model of Triton's atmosphere, in which only solar radiation is present, predicts a large column of carbon atoms. With an assumed, but reasonable, rate of charge transfer between N2+ and C, a peak C+ abundance results that is close to the peak electron densities measured by Voyager in Triton's ionosphere. These results suggest that Triton's upper atmospheric chemistry may thus be solar-controlled. Measurement of key reaction rate constants, currently unknown or highly uncertain at Triton's low temperatures, would help to clarify the chemical and physical processes occurring in Triton's atmosphere. C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. RP LYONS, JR (reprint author), CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125, USA. NR 32 TC 10 Z9 10 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 10 PY 1992 VL 256 IS 5054 BP 204 EP 206 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA HM896 UT WOS:A1992HM89600023 PM 11540928 ER PT J AU ALBRECHT, A STEBBINS, A AF ALBRECHT, A STEBBINS, A TI PERTURBATIONS FROM COSMIC STRINGS IN COLD DARK MATTER SO PHYSICAL REVIEW LETTERS LA English DT Article ID GALAXY FORMATION; DENSITY-FLUCTUATIONS; SCALE STRUCTURE; EVOLUTION; UNIVERSE AB We present a systematic linear analysis of the perturbations induced by cosmic strings in cold dark matter. We calculate the power spectrum and find that the strings produce a great deal of power on small scales. We show that the perturbations on interesting scales are the result of many uncorrelated string motions, which indicates a more "Gaussian" distribution than was previously supposed. RP ALBRECHT, A (reprint author), NASA,FERMILAB ASTROPHYS CTR,POB 500,BATAVIA,IL 60510, USA. NR 25 TC 70 Z9 70 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 APR 6 PY 1992 VL 68 IS 14 BP 2121 EP 2124 DI 10.1103/PhysRevLett.68.2121 PG 4 WC Physics, Multidisciplinary SC Physics GA HM440 UT WOS:A1992HM44000004 ER PT J AU LANGHOFF, SR BAUSCHLICHER, CW PARTRIDGE, H TAYLOR, PR AF LANGHOFF, SR BAUSCHLICHER, CW PARTRIDGE, H TAYLOR, PR TI THEORETICAL BOND-ENERGIES FOR COVALENT AND IONIC MOLECULES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 5 PY 1992 VL 203 BP 1 EP COMP PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HK161 UT WOS:A1992HK16101886 ER PT J AU KAYE, JA AF KAYE, JA TI STABLE ISOTOPES AS PROBES OF SOURCES, SINKS, AND TRANSFORMATIONS OF ATMOSPHERIC TRACE SPECIES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,DIV EARTH SCI & APPLICAT,WASHINGTON,DC 20546. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 5 PY 1992 VL 203 BP 3 EP NUCL PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HK162 UT WOS:A1992HK16201227 ER PT J AU CHANG, S AF CHANG, S TI ISOTOPIC COMPOSITION OF ORGANIC-COMPOUNDS IN CARBONACEOUS METEORITES - A STATUS-REPORT SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 5 PY 1992 VL 203 BP 4 EP NUCL PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HK162 UT WOS:A1992HK16201228 ER PT J AU JENSEN, BJ AF JENSEN, BJ TI LARCTM-ITPI ARYLENE ETHER COPOLYMERS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. ANALYT SERV & MAT INC,HAMPTON,VA 23666. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 5 PY 1992 VL 203 BP 55 EP POLY PN 3 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HK163 UT WOS:A1992HK16300055 ER PT J AU JENSEN, BJ AF JENSEN, BJ TI FLUORINE CONTAINING IMIDE ARYLENE ETHER COPOLYMERS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 5 PY 1992 VL 203 BP 56 EP POLY PN 3 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HK163 UT WOS:A1992HK16300056 ER PT J AU SHAO, M HALL, KW VALENTIN, JR PHILLIPS, JB AF SHAO, M HALL, KW VALENTIN, JR PHILLIPS, JB TI A COMPARATIVE-STUDY OF COMPUTATIONAL ANALYSIS TECHNIQUES FOR DECONVOLUTION OF MULTIPLEX GAS-CHROMATOGRAPHIC DATA SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 SAN JOSE STATE UNIV,DEPT PHYS,SAN JOSE,CA 95192. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SO ILLINOIS UNIV,DEPT CHEM & BIOCHEM,CARBONDALE,IL 62901. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 5 PY 1992 VL 203 BP 57 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HK161 UT WOS:A1992HK16100404 ER PT J AU SHARP, TG BANIN, A BUSECK, PR AF SHARP, TG BANIN, A BUSECK, PR TI MORPHOLOGY AND STRUCTURE OF MONTMORILLONITE SURFACES WITH ATOMIC-FORCE MICROSCOPY SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV BAYREUTH,BAYER GEOINST,W-8580 BAYREUTH,GERMANY. ARIZONA STATE UNIV,DEPT CHEM,TEMPE,AZ 85287. ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 5 PY 1992 VL 203 BP 57 EP GEOC PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HK161 UT WOS:A1992HK16102527 ER PT J AU DAO, MD VALENTIN, JR BANIN, A PHILLIPS, JB AF DAO, MD VALENTIN, JR BANIN, A PHILLIPS, JB TI DEVELOPMENT OF A SOIL-WATER VAPOR ANALYZER FOR MARS MISSIONS USING CHEMICAL MODULATION SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 SAN JOSE STATE UNIV,DEPT CHEM,SAN JOSE,CA 95192. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. HEBREW UNIV JERUSALEM,DEPT SOIL & WATER SCI,IL-76100 REHOVOT,ISRAEL. SO ILLINOIS UNIV,DEPT CHEM & BIOCHEM,CARBONDALE,IL 62901. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 5 PY 1992 VL 203 BP 60 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA HK161 UT WOS:A1992HK16100407 ER EF