FN Thomson Reuters Web of Science™ VR 1.0 PT J AU MANNEY, GL FROIDEVAUX, L WATERS, JW ZUREK, RW READ, WG ELSON, LS KUMER, JB MERGENTHALER, JL ROCHE, AE ONEILL, A HARWOOD, RS MACKENZIE, I SWINBANK, R AF MANNEY, GL FROIDEVAUX, L WATERS, JW ZUREK, RW READ, WG ELSON, LS KUMER, JB MERGENTHALER, JL ROCHE, AE ONEILL, A HARWOOD, RS MACKENZIE, I SWINBANK, R TI CHEMICAL DEPLETION OF OZONE IN THE ARCTIC - LOWER STRATOSPHERE DURING WINTER 1992-93 SO NATURE LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; MICROWAVE LIMB SOUNDER; POLAR VORTEX; POTENTIAL VORTICITY; MLS OBSERVATIONS; ANTARCTIC OZONE; EVOLUTION; CHLORINE; ER-2; SOUTHERN AB Satellite observations of ozone and chlorine monoxide concentrations during winter 1992-1993 show that in February 1993 chlorine in the lower stratosphere was mostly in chemically reactive forms. Decreases in stratospheric ozone concentration during February and early March 1993 are consistent with chemical destruction by this reactive chlorine. Comparison with changes in the distribution of long-lived chemical and dynamical tracers shows that the observed decrease cannot have been caused solely by dynamical processes. C1 LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. UNIV READING,CTR GLOBAL ATMOSPHER MODELING,DEPT METEOROL,READING RG6 2AU,BERKS,ENGLAND. UNIV EDINBURGH,DEPT METEOROL,EDINBURGH EH9 3JZ,MIDLOTHIAN,SCOTLAND. METEOROL OFF,BRACKNELL RG12 2SZ,BERKS,ENGLAND. RP MANNEY, GL (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI mackenzie, ian/E-9320-2013 NR 44 TC 124 Z9 128 U1 1 U2 9 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD AUG 11 PY 1994 VL 370 IS 6489 BP 429 EP 434 DI 10.1038/370429a0 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PB407 UT WOS:A1994PB40700047 ER PT J AU KOIKE, M BEGUIRISTAIN, R UNDERWOOD, JH NAMIOKA, T AF KOIKE, M BEGUIRISTAIN, R UNDERWOOD, JH NAMIOKA, T TI A NEW OPTICAL DESIGN METHOD AND ITS APPLICATION TO AN EXTREME-ULTRAVIOLET VARIED LINE SPACING PLANE GRATING MONOCHROMATOR SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 8th National Conference on Synchrotron Radiation Instrumentation CY AUG 23-26, 1993 CL NIST, GAITHERSBURG, MD HO NIST AB A new design method has been developed for a double-element optical system. The method incorporates a very simple ray tracing procedure into an analytic merit function that closely represents the variance of an infinite number of ray-traced spots in the image plane. A 174-degrees constant-deviation objective Monk-Gillieson monochromator consisting of a highly demagnifying (approximately 1/10) spherical mirror, varied spacing plane grating, and elliptic cylindrical focusing mirror has been designed for a bending-magnet beamline using the new design method. Ray-tracing results show that the new design can provide higher spectral purity and throughput as compared to a design based on the light path function and that the monochromator design gives slit-width-limited resolutions over a wavelength range of 2-5 nm. C1 UNIV SPACE RES ASSOC,NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP KOIKE, M (reprint author), LAWRENCE BERKELEY LAB,CTR XRAY OPT,BERKELEY,CA 94720, USA. NR 14 TC 24 Z9 25 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD AUG 11 PY 1994 VL 347 IS 1-3 BP 273 EP 277 DI 10.1016/0168-9002(94)91891-0 PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA PD429 UT WOS:A1994PD42900048 ER PT J AU KOIKE, M HEIMANN, PA KUNG, AH NAMIOKA, T DIGENNARO, R GEE, B YU, N AF KOIKE, M HEIMANN, PA KUNG, AH NAMIOKA, T DIGENNARO, R GEE, B YU, N TI VUV HIGH-RESOLUTION AND HIGH-FLUX BEAMLINE FOR CHEMICAL-DYNAMICS STUDIES AT THE ADVANCED LIGHT-SOURCE SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article; Proceedings Paper CT 8th National Conference on Synchrotron Radiation Instrumentation CY AUG 23-26, 1993 CL NIST, GAITHERSBURG, MD HO NIST ID SPECTROSCOPIC FACILITY AB An undulator beamline, consisting of VUV high resolution and high flux branch lines, devoted to chemical dynamics experiments has been designed at the Advanced Light Source. The radiation source is an undulator having a 10-cm period, and the fundamental in the energy range from 6 to 30 eV is utilized by the experiments. The higher harmonics of the undulator due to the operation at high K values is suppressed by a novel gas filter. In the first branch, high-flux 2% bandwidth radiation is directed toward an end station for photodissociation. A photon flux calculation predicts 1016 photon/s at this end station. In the second branch, highly monochromatized radiation is sent to an end station for photoelectron spectroscopy and photoionization studies. For this purpose a vertical dispersion 6.65-m off-plane Eagle mounting was chosen for the monochromator in anticipation of achieving a resolving power of approximately 5 X 10(4) with a 1200 grooves/mm grating and 1 X 10(5) to 2 x 10(5) with a 4800 grooves/mm grating. C1 LAWRENCE BERKELEY LAB,DIV ACCELERATOR & FUS RES,BERKELEY,CA 94720. UNIV SPACE RES ASSOC,NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. LAWRENCE BERKELEY LAB,DIV ENGN,BERKELEY,CA 94720. LAWRENCE BERKELEY LAB,DIV CHEM SCI,BERKELEY,CA 94720. RP KOIKE, M (reprint author), LAWRENCE BERKELEY LAB,CTR X RAY OPT,DIV MAT SCI,BERKELEY,CA 94720, USA. RI Kung, Andy/F-7909-2012 NR 10 TC 36 Z9 36 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD AUG 11 PY 1994 VL 347 IS 1-3 BP 282 EP 286 DI 10.1016/0168-9002(94)91893-7 PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA PD429 UT WOS:A1994PD42900050 ER PT J AU ZHOU, SM WU, WS CAMPBELL, S YEH, PC YANG, XY LIU, HK AF ZHOU, SM WU, WS CAMPBELL, S YEH, PC YANG, XY LIU, HK TI OPTICAL IMPLEMENTATION OF FUZZY-SET REASONING SO APPLIED OPTICS LA English DT Article ID LOGIC AB New methods of optical fuzzy-logic operations and optical fuzzy-controller synthesis are proposed and experimentally demonstrated by use of optical fan-out elements to achieve multiple imaging and polarization-space/aperture data encoding to represent fuzzy variables in optics. Sixteen fuzzy-logic operations between two inputs are achieved by use of a simple polarization-space data-encoding and kernel-operation scheme. In addition, a max-min composition-based fuzzy controller is implemented by use of an aperture-data-encoding and a double-multi-imaging approach. Our systems exhibit a high operation speed, a large information throughput, and a high signal-to-noise ratio. C1 QUANTEX CORP, ROCKVILLE, MD 20850 USA. CALTECH, JET PROP LAB, CTR SPACE MICROELECTR TECHNOL, PASADENA, CA 91109 USA. RP ZHOU, SM (reprint author), UNIV CALIF SANTA BARBARA, DEPT ELECT & COMP ENGN, SANTA BARBARA, CA 93106 USA. RI Yeh, Pochi/A-2109-2010 NR 22 TC 14 Z9 16 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD AUG 10 PY 1994 VL 33 IS 23 BP 5335 EP 5347 PG 13 WC Optics SC Optics GA PD325 UT WOS:A1994PD32500014 PM 20935924 ER PT J AU HINSHAW, G KOGUT, A GORSKI, KM BANDAY, AJ BENNETT, CL LINEWEAVER, C LUBIN, P SMOOT, GF WRIGHT, EL AF HINSHAW, G KOGUT, A GORSKI, KM BANDAY, AJ BENNETT, CL LINEWEAVER, C LUBIN, P SMOOT, GF WRIGHT, EL TI LIMITS ON 3-POINT CORRELATIONS IN THE COBE DMR 1ST-YEAR ANISOTROPY MAPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS ID DIFFERENTIAL MICROWAVE RADIOMETERS AB We compute the three-point temperature correlation function of the COBE Differential Microwave Radiometer (DMR) first-year sky maps to search for non-Gaussian temperature fluctuations. The level of fluctuations seen in the computed correlation function are too large to be attributable solely to instrument noise. However the fluctuations are consistent with the level expected to result from a superposition of instrument noise and sky signal arising from a Gaussian power-law model of initial fluctuations, with a quadrupole normalized amplitude of 17 muK and a power-law spectral index n = 1. We place limits on the amplitude of intrinsic three-point correlations with a variety of predicted functional forms. C1 NASA, GODDARD SPACE FLIGHT CTR, GSFC, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. UNIV CALIF BERKELEY, LBL, SSL, BERKELEY, CA 94720 USA. UCSB, DEPT PHYS, SANTA BARBARA, CA 93106 USA. UNIV CALIF LOS ANGELES, DEPT ASTRN, LOS ANGELES, CA 90024 USA. RP HINSHAW, G (reprint author), HUGHES STX CORP, NASA, GSFC, CODE 685 9, GREENBELT, MD 20771 USA. RI Kogut, Alan/D-6293-2012 NR 15 TC 30 Z9 30 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1994 VL 431 IS 1 BP 1 EP 5 DI 10.1086/174462 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ977 UT WOS:A1994NZ97700001 ER PT J AU LOEWENSTEIN, M AF LOEWENSTEIN, M TI IMPLICATIONS FOR GRAVITATIONAL LENSING AND THE DARK-MATTER CONTENT IN CLUSTERS OF GALAXIES FROM SPATIALLY-RESOLVED X-RAY-SPECTRA SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GALAXIES, CLUSTERS, INDIVIDUAL (PERSEUS, A2256); GRAVITATIONAL LENSING; INTERGALACTIC MEDIUM; X-RAYS, GALAXIES ID PERSEUS CLUSTER; MASS-DISTRIBUTION; RICH CLUSTERS; COMA CLUSTER; MORPHOLOGY; A2256; FLUX AB A simple method for deriving well-behaved temperature solutions to the equation of hydrostatic equilibrium for intracluster media with X-ray imaging observations is presented and applied to a series of generalized models as well as to observations of the Perseus cluster and Abell 2256. In these applications the allowed range in the ratio of nonbaryons to baryons as a function of radius is derived, taking into account the uncertainties and crude spatial resolution of the X-ray spectra and considering a range of physically reasonable mass models with various scale heights. Particular attention is paid to the central regions of the cluster, and it is found that the dark matter can be sufficiently concentrated to be consistent with the high central mass surface densities derived for moderate-redshift clusters from their gravitational lensing properties. C1 UNIV SPACE RES ASSOC,COLUMBIA,MD. RP LOEWENSTEIN, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771, USA. NR 20 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1994 VL 431 IS 1 BP 91 EP 103 DI 10.1086/174469 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ977 UT WOS:A1994NZ97700008 ER PT J AU VANCURA, O RAYMOND, JC DWEK, E BLAIR, WP LONG, KDS FOSTER, S AF VANCURA, O RAYMOND, JC DWEK, E BLAIR, WP LONG, KDS FOSTER, S TI A STUDY OF X-RAY AND INFRARED EMISSIONS FROM DUSTY NONRADIATIVE SHOCK-WAVES SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; ISM, ABUNDANCES; ISM, INDIVIDUAL (CYGNUS LOOP); SHOCK WAVES; SUPERNOVA REMNANTS ID CYGNUS LOOP; TEMPERATURE-FLUCTUATIONS; INTERSTELLAR GRAINS; SUPERNOVA-REMNANTS; HOT GAS; DESTRUCTION; SPECTRUM AB We have constructed models that predict the dynamic evolution and infrared (IR) emission of grains behind nonradiative shock waves. We present a self-consistent treatment of the effect of grain destruction and heating on the ionization structure and X-ray emission of the postshock gas. Incorporating thermal sputtering, collisional heating, and deceleration of grains in the postshock flow, we predict the IR and X-ray fluxes from the dusty plasma as a function of swept-up column density. Heavy elements such as C, O, Mg, S, Si, and Fe are initially depleted from the ps phase but are gradually returned as the grains are destroyed. The injected neutral atoms require some time to ''catch up'' with the ionization state of the ambient ps. The nonequilibrium ionization state and gradient in elemental abundances in the postshock flow produces characteristic X-ray signatures that can be related to the age of the shock and amount of grain destruction. We study the effects of preshock density and shock velocity on the X-ray and IR emission from the shock. We show that the effects of grain destruction on the X-ray spectra of shock waves are substantial. In particular, temperatures derived from X-ray spectra of middle-aged remnants are likely to be overestimated by approximately 15% if cosmic abundances are assumed. Due to the long timescale for grain destruction in X-ray gases over a wide range of temperatures, we suggest that future X-ray spectral studies of supernova remnants be based on depleted abundances instead of cosmic abundances. Our model predictions agree reasonably well with IRAS and Einstein IPC observations of the Cygnus Loop. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,CTR ASTROPHYS SCI,BALTIMORE,MD 21218. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP VANCURA, O (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. NR 33 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 AUG 10 PY 1994 VL 431 IS 1 BP 188 EP 200 DI 10.1086/174477 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ977 UT WOS:A1994NZ97700016 ER PT J AU RAPPAPORT, S CHIANG, E KALLMAN, T MALINA, R AF RAPPAPORT, S CHIANG, E KALLMAN, T MALINA, R TI IONIZATION NEBULAE SURROUNDING SUPERSOFT X-RAY SOURCES SO ASTROPHYSICAL JOURNAL LA English DT Article DE BINARIES, CLOSE; H II REGIONS; ISM, GENERAL; H II REGIONS; WHITE DWARFS X-RAYS, ISM ID LARGE MAGELLANIC CLOUD; H-II-REGIONS; GALAXIES; BINARY; LMC; SPECTRA; CAL-87; REMNANTS; MODELS AB In this work we carry out a theoretical investigation of a new type of astrophysical gaseous nebula, viz., ionized regions surrounding supersoft X-ray sources. Supersoft X-ray sources, many of which have characteristic luminosities of approximately 10(37)-10(38) ergs s-1 and effective temperatures of approximately 4 x 10(5) K, were first discovered with the Einstein Observatory. These sources have now been shown to constitute a distinct class of X-ray source and are being found in substantial numbers with ROSAT. We predict that these sources should be surrounded by regions of ionized hydrogen and helium with properties that are distinct from other astrophysical gaseous nebulae. We present calculations of the ionization and temperature structure of these ionization nebulae, as well as the expected optical line fluxes. The ionization profiles for both hydrogen and helium exhibit substantially more gradual transitions from the ionized to the unionized state than is the case for conventional H II regions. The calculated optical line intensities are presented as absolute fluxes from sources in the Large Magellanic Cloud and as fractions of the central source luminosity. We find, in particular, that [O III] lambda5008 and He II lambda4686 are especially prominent in these ionization nebulae as compared to other astrophysical nebulae. We propose that searches for supersoft X-rays via their characteristic optical lines may reveal sources in regions where the soft X-rays are nearly completely absorbed by the interstellar medium. C1 MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF BERKELEY,CTR ENV ASTROPHYS,BERKELEY,CA 94720. RP RAPPAPORT, S (reprint author), MIT,DEPT PHYS,CAMBRIDGE,MA 02139, USA. OI malina, roger/0000-0003-3399-3865 NR 38 TC 52 Z9 52 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1994 VL 431 IS 1 BP 237 EP 246 DI 10.1086/174481 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ977 UT WOS:A1994NZ97700020 ER PT J AU KO, YK KALLMAN, TR AF KO, YK KALLMAN, TR TI EMISSION-LINES FROM X-RAY-HEATED ACCRETION DISKS IN LOW-MASS X-RAY BINARIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; BINARIES, CLOSE; STARS, CORONAE; X-RAYS, STARS ID VERTICAL STRUCTURE; SCORPIUS X-1; BLACK-HOLES; CORONAE; MODEL; WINDS; ELEMENTS; SPECTRUM; OSCILLATIONS; INSTABILITY AB We investigate the structure of accretion disks illuminated by X-rays from a central compact object in a binary system. X-rays can photoionize the upper atmosphere of the disk and form an accretion disk corona (ADC) where emission lines can form. We construct a model to calculate the vertical structure and the emission spectrum of the ADC with parameters appropriate to low-mass X-ray binaries. These models are made by nonlocal thermodynamic equilibrium calculations of ion and level populations and include a large number of atomic processes for 10 cosmically abundant elements. Transfer of radiation is treated by using the escape probability formalism. The vertical temperature profile of the ADC consists of a Compton-heated region and a mid-T zone where the temperature is approximately 10(6) K. A thermal instability occurs close to the disk photosphere and causes the temperature of the ADC to drop abruptly from 10(6) K to several times 10(4) K. The emission spectrum in the optical, ultraviolet, extreme ultraviolet, and X-ray range is discussed and compared with the observations. C1 UNIV CALIF BERKELEY,CTR EUV ASTROPHYS,BERKELEY,CA 94720. RP KO, YK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 665,GREENBELT,MD 20771, USA. NR 61 TC 73 Z9 73 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1994 VL 431 IS 1 BP 273 EP 301 DI 10.1086/174485 PN 1 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ977 UT WOS:A1994NZ97700024 ER PT J AU TIELENS, AGGM MCKEE, CF SEAB, CG HOLLENBACH, DJ AF TIELENS, AGGM MCKEE, CF SEAB, CG HOLLENBACH, DJ TI THE PHYSICS OF GRAIN-GRAIN COLLISIONS AND GAS-GRAIN SPUTTERING IN INTERSTELLAR SHOCKS SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; SHOCK WAVES ID INTER-STELLAR SPACE; PYROLYTIC-GRAPHITE; DUST GRAINS; STAINLESS-STEEL; CH4 FORMATION; ENERGY-RANGE; HYDROGEN; IONS; DESTRUCTION; BOMBARDMENT AB Grain-grain collisions and ion sputtering destroy dust grains in interstellar shocks. An analytical theory is developed for the propagation of shock waves in solids driven by grain-grain collisions, which compares very favorably with detailed numerical calculations. This theory is used to determine the fraction of a grain vaporized by a grain-grain collision. Our results predict much less vaporization of colliding grains in interstellar shocks than previous estimates. This theory can also be used to determine the fraction of a colliding grain that melts, shatters, or undergoes a phase transformation to a higher density phase. In particular, the latter two processes can be much more important in interstellar shocks than vaporization. The sputtering of grains by impacting gas ions is reanalyzed based upon extensive laboratory studies and a theoretically derived ''universal'' sputtering relation. The analytical results are compared to available experimental studies of sputtering of graphite/amorphous carbon, SiO2, SiC, Fe, and H2O. Sputtering yields for astrophysically relevant materials as a function of impact energy and ion mass are derived. These yields are also averaged over thermal impact spectrum and simple polynomial fits to the resulting yields as a function of temperature are presented. The derived sputtering yields are similar to those adopted in previous studies, except for graphite near threshold where the new yields are much larger due to a lower adopted binding energy. The ion bombardment will amorphitize the surface layers of interstellar grains. It will also convert graphite into hydrogenated amorphous carbon (HAC) to a depth of 10-20 angstrom. It is suggested that these HAC surfaces are the carriers of the 3.4 mum absorption feature in the interstellar medium. C1 UNIV NEW ORLEANS, DEPT PHYS, NEW ORLEANS, LA 70148 USA. UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. NASA, AMES RES CTR, MAILSTOP 245-3, MOFFETT FIELD, CA 94035 USA. RP TIELENS, AGGM (reprint author), UNIV CALIF BERKELEY, DEPT PHYS, BERKELEY, CA 94720 USA. NR 107 TC 216 Z9 217 U1 1 U2 8 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 AUG 10 PY 1994 VL 431 IS 1 BP 321 EP 340 DI 10.1086/174488 PN 1 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ977 UT WOS:A1994NZ97700027 ER PT J AU PENDLETON, GN PACIESAS, WS BRIGGS, MS MALLOZZI, RS KOSHUT, TM FISHMAN, GJ MEEGAN, CA WILSON, RB HARMON, AB KOUVELIOTOU, C AF PENDLETON, GN PACIESAS, WS BRIGGS, MS MALLOZZI, RS KOSHUT, TM FISHMAN, GJ MEEGAN, CA WILSON, RB HARMON, AB KOUVELIOTOU, C TI THE CONTINUUM SPECTRAL CHARACTERISTICS OF GAMMA-RAY BURSTS OBSERVED BY BATSE SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS; BURSTS AB Distributions of the continuum spectral characteristics of 260 bursts in the first BATSE catalog are presented. The data are derived from flux ratios calculated from the BATSE Large Area Detector (LAD) four-channel discriminator data. The data are converted from counts to photons using a direct spectral inversion technique to remove the effects of atmospheric scattering and the energy dependence of the detector angular response. Although there are intriguing clusterings of bursts in the spectral hardness ratio distributions, no evidence for the presence of distinct burst classes based on spectral hardness ratios alone is found. All subsets of bursts selected for their spectral characteristics in this analysis exhibit spatial distributions consistent with isotropy. The spectral diversity of the burst population appears to be caused largely by the highly variable nature of the burst production mechanisms themselves. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP PENDLETON, GN (reprint author), UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899, USA. NR 18 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 AUG 10 PY 1994 VL 431 IS 1 BP 416 EP 424 DI 10.1086/174495 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ977 UT WOS:A1994NZ97700034 ER PT J AU BOYD, PT MINDLIN, GB GILMORE, R SOLARI, HG AF BOYD, PT MINDLIN, GB GILMORE, R SOLARI, HG TI TOPOLOGICAL ANALYSIS OF CHAOTIC ORBITS - REVISITING HYPERION SO ASTROPHYSICAL JOURNAL LA English DT Article DE CELESTIAL MECHANICS, STELLAR DYNAMICS; METHODS, ANALYTICAL; PLANETS AND SATELLITES, INDIVIDUAL (HYPERION, SATURN) ID STRANGE ATTRACTORS; ROTATION AB There is emerging interest in the possibility of chaotic evolution in astrophysical systems. To mention just one example, recent well-sampled ground-based observations of the Saturnian satellite Hyperion strongly suggest that it is exhibiting chaotic behavior. We present a general technique, the method of close returns, for the analysis of data from astronomical objects believed to be exhibiting chaotic motion. The method is based on the extraction of pieces of the evolution that exhibit nearly periodic behavior-episodes during which the object stays near in phase space to some unstable periodic orbit. Such orbits generally act as skeletal features, tracing the topological organization of the manifold on which the chaotic dynamics takes place. This method does not require data sets as lengthy as other nonlinear analysis techniques do and is therefore well suited to many astronomical observing programs. Well sampled data covering between twenty and forty characteristic periods of the system have been found to be sufficient for the application of this technique. Additional strengths of this method are its robustness in the presence of noise and the ability for a user to clearly distinguish between periodic, random, and chaotic behavior by inspection of the resulting two-dimensional image. As an example of its power, we analyze close returns in a numerically generated data set, based on a model for Hyperion extensively studied in the literature, corresponding to nightly observations of the satellite. We show that with a small data set, embedded unstable periodic orbits can be extracted and that these orbits can be responsible for nearly periodic behavior lasting a substantial fraction of the observing run. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. UNIV BUENOS AIRES, FCEN, DEPT FIS, RA-1428 BUENOS AIRES, ARGENTINA. DREXEL UNIV, DEPT PHYS & ATMOSPHER SCI, PHILADELPHIA, PA 19104 USA. RP BOYD, PT (reprint author), UNIV SPACE RES ASSOC, COLUMBIA, MD USA. RI Boyd, Patricia/D-3274-2012; OI Solari, Hernan/0000-0003-4287-1878 NR 16 TC 8 Z9 8 U1 1 U2 4 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 AUG 10 PY 1994 VL 431 IS 1 BP 425 EP 431 DI 10.1086/174496 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ977 UT WOS:A1994NZ97700035 ER PT J AU BERRIMAN, GB BOGGESS, NW HAUSER, MG KELSALL, T LISSE, CM MOSELEY, SH REACH, WT SILVERBERG, RF AF BERRIMAN, GB BOGGESS, NW HAUSER, MG KELSALL, T LISSE, CM MOSELEY, SH REACH, WT SILVERBERG, RF TI COBE DIRBE NEAR-INFRARED POLARIMETRY OF THE ZODIACAL LIGHT - INITIAL RESULTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOLAR SYSTEM; INSTRUMENTATION, POLARIMETERS; INTERPLANETARY MEDIUM; POLARIZATION; SOLAR SYSTEM, GENERAL; TECHNIQUES, POLARIMETRIC AB This Letter describes near-infrared polarimetry of the zodiacal light at 2.2 mum, measured with the Diffuse Infrared Background Experiment (DIRBE) aboard the Cosmic Background Explorer (COBE) spacecraft. The polarization is due to scattering of sunlight. The polarization vector is perpendicular to the scattering plane, and its observed amplitude on the ecliptic equator at an elongation of 90-degrees and ecliptic longitude of 10-degrees declines from 12.0 +/- 0.4% at 1.25 mum to 8.0 +/- 0.6% at 3.5 mum (cf. 16% in the visible); the principal source of uncertainty is photometric noise due to stars. The observed near-infrared colors at this location are redder than Solar, but at 3.5 mum this is due at least in part to the thermal emission contribution from the interplanetary dust. Mie theory calculations show that both polarizations and colors are important in constraining models of interplanetary dust. C1 NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. RP BERRIMAN, GB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEN SCI CORP,CODE 6853,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012; Lisse, Carey/B-7772-2016; OI Lisse, Carey/0000-0002-9548-1526; Reach, William/0000-0001-8362-4094 NR 21 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1994 VL 431 IS 1 BP L63 EP & DI 10.1086/187473 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ979 UT WOS:A1994NZ97900016 ER PT J AU FRIEMAN, J SCOCCIMARRO, R AF FRIEMAN, J SCOCCIMARRO, R TI CAN MACHOS PROBE THE SHAPE OF THE GALAXY HALO SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GRAVITATIONAL LENSING; MAGELLANIC CLOUDS ID GALACTIC HALO; DARK MATTER; OBJECTS; STAR AB Microlensing searches in our galaxy have recently discovered several candidates in the direction of the Large Magellanic Cloud (LMC). We study the prospects for such searches to yield useful information about the flattening of the Galaxy dark matter halo, using a self-consistent oblate halo model and allowing for the possibility of misalignment between the disk and halo symmetry axes. The microlensing optical depth for the LMC, tau(LMC), depends sensitively on the disk-halo tilt angle in the Milky Way, as does the ratio tau(SMC)/tau(LMC). If the tilt angle is as large as 30-degrees, a much larger spread in values for tau(LMC) is consistent with rotation curve constraints than previously thought. Disk-halo tilt and halo flattening do not significantly affect the MACHO masses inferred from event durations. C1 UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637. RP FRIEMAN, J (reprint author), NASA,CTR ASTROPHYS,FERMILAB,FERMI NATL ACCELERATOR LAB,POB 500,BATAVIA,IL 60510, USA. NR 29 TC 19 Z9 19 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1994 VL 431 IS 1 BP L23 EP L26 DI 10.1086/187463 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ979 UT WOS:A1994NZ97900006 ER PT J AU HURLEY, K SOMMER, M KOUVELIOTOU, C FISHMAN, G MEEGAN, C CLINE, T BOER, M NIEL, M AF HURLEY, K SOMMER, M KOUVELIOTOU, C FISHMAN, G MEEGAN, C CLINE, T BOER, M NIEL, M TI NETWORK SYNTHESIS LOCALIZATION OF 2 SOFT GAMMA REPEATERS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, BURSTS; STARS, NEUTRON ID HIGH-ENERGY TRANSIENT; RAY BURST; SUPERNOVA-REMNANTS AB We introduce the method of ''network synthesis,'' which allows the detection of very weak gamma-ray transient signals in the data of the Ulysses gamma-ray burst (GRB) experiment from repeating sources. It consists of defining a grid of alpha, delta values, and for each BATSE detection of a burst from a soft gamma repeater, predicting the arrival time of the burst at Ulysses and co-adding the Ulysses data rephased so that the burst signals are aligned in time and produce a detectable pulse. We demonstrate that this method identifies the position of the soft repeater SGR 1806 - 20, and apply it to the repeater B 1900 + 14. We show that the counterpart to this burst source is probably in or in the vicinity of the Galactic supernova remnant G42.8 + 0.6. C1 MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. CTR ETUD SPATIALE RAYONNEMENTS,F-31400 TOULOUSE,FRANCE. RP HURLEY, K (reprint author), UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720, USA. NR 22 TC 46 Z9 46 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1994 VL 431 IS 1 BP L31 EP L34 DI 10.1086/187465 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ979 UT WOS:A1994NZ97900008 ER PT J AU SKIBO, JG DERMER, CD RAMATY, R AF SKIBO, JG DERMER, CD RAMATY, R TI COMPTON-SCATTERING IN JETS - A MECHANISM FOR SIMILAR-TO-0.4 AND LESS-THAN-OR-EQUAL-TO-0.2 MEV LINE PRODUCTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, THEORY; RADIATION MECHANISMS, NONTHERMAL; BLACK HOLE PHYSICS; LINE, FORMATION ID GALACTIC-CENTER REGION; POSITRON-ANNIHILATION RADIATION; GAMMA-RAY LINES; CENTER DIRECTION; BLACK-HOLE; NOVA; 1E1740.7-2942; EMISSION; MUSCA AB We show that gamma-ray line emission at approximately 0.4 and less than or similar to 0.2 MeV can be produced by Compton scattering of beamed radiation in the jets of Galactic black hole candidates. This mechanism has the novel feature of not invoking the presence of e+-e- pairs. To produce the two lines, we employ a symmetric double-sided jet with bulk flow velocity of about 0.5c and incident beam radiation with a hard energy spectrum. We show that the two lines can be seen at viewing-angle cosines relative to the jet ranging from 0.2 to 0.6. This comprises 40% of the total solid angle. In addition, the line radiation is approximately 10% polarized. Depending on the bulk flow and viewing angle, the model can produce lines at other energies as well. In particular, a broad feature near 1 MeV can be seen by viewing the jet close to its axis. Our model can also accommodate single-line spectra if the beamed gamma-ray emission or the jets themselves are asymmetric. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP SKIBO, JG (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,NRC,WASHINGTON,DC 20375, USA. NR 25 TC 11 Z9 11 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 10 PY 1994 VL 431 IS 1 BP L39 EP L42 DI 10.1086/187467 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ979 UT WOS:A1994NZ97900010 ER PT J AU NEVES, JC MOIN, P MOSER, RD AF NEVES, JC MOIN, P MOSER, RD TI EFFECTS OF CONVEX TRANSVERSE CURVATURE ON WALL-BOUNDED TURBULENCE .1. THE VELOCITY AND VORTICITY SO JOURNAL OF FLUID MECHANICS LA English DT Article ID CHANNEL FLOW; AXIAL-FLOW; LAYER; CYLINDER; THICK AB Convex transverse curvature effects in wall-bounded turbulent flows are significant if the boundary-layer thickness is large compared to the radius of curvature (large gamma = delta/a). The curvature affects the inner part of the flow if a+, the cylinder radius in wall units, is small. Two direct numerical simulations of a model problem approximating axial flow boundary layers on long cylinders were performed for gamma = 5 (a+ almost-equal-to 43) and gamma = 11 (a+ almost-equal-to 21). Statistical and structural data were extracted from the computed flow fields. The effects of the transverse curvature were identified by comparing the present results with those of the plane channel simulation of Kim, Moin & Moser (1987), performed at a similar Reynolds number. As the curvature increases, the skin friction increases, the slope of the logarithmic region decreases and turbulence intensities are reduced. Several turbulence statistics are found to scale with a curvature dependent velocity scale derived from the mean momentum equation. Near the wall, the flow is more anisotropic than in the plane channel with a larger percentage of the turbulent kinetic energy resulting from the streamwise velocity fluctuations. As the curvature increases, regions of strong normal vorticity develop near the wall. C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 30 TC 45 Z9 45 U1 2 U2 7 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD AUG 10 PY 1994 VL 272 BP 349 EP 381 DI 10.1017/S0022112094004490 PG 33 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PC924 UT WOS:A1994PC92400015 ER PT J AU NEVES, JC MOIN, P AF NEVES, JC MOIN, P TI EFFECTS OF CONVEX TRANSVERSE CURVATURE ON WALL-BOUNDED TURBULENCE .2. THE PRESSURE-FLUCTUATIONS SO JOURNAL OF FLUID MECHANICS LA English DT Article ID CHANNEL FLOW; LAYERS AB The effects of convex transverse curvature on the wall pressure fluctuations were studied through direct numerical simulations. The flow regime of interest is characterized by large ratio of the shear-layer thickness to the radius of curvature (gamma = delta/a) and by small a+, the radius of curvature in wall units. Two direct numerical simulations of a model problem approximating axial flow boundary layers on long cylinders were performed for gamma = 5 (a+ almost-equal-to 43) and gamma = 11 (a+ almost-equal-to 21). The space-time characteristics of the wall pressure fluctuations of the plane channel flow simulation of Kim, Moin & Moser (1987), which were studied by Choi & Moin (1990) are used to assess the effects of curvature. As the curvature increases the root-mean-square (r.m.s.) pressure fluctuations decrease and the ratio of the streamwise to spanwise lengthscales of the wall pressure fluctuations increases. Fractional contributions from various layers in the flow to the wall r.m.s. pressure fluctuations are marginally affected by the curvature. Curvature-dependent timescales and lengthscales are identified that collapse the high-frequency range of the wall pressure temporal spectra and the high wave-number range of the wall pressure streamwise spectra of flows with different curvatures. Taylor's hypothesis holds for the wall pressure fluctuations with a lower convection velocity than in the planar case. C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 18 TC 20 Z9 20 U1 1 U2 5 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD AUG 10 PY 1994 VL 272 BP 383 EP 406 DI 10.1017/S0022112094004507 PG 24 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA PC924 UT WOS:A1994PC92400016 ER PT J AU HOOK, SJ KARLSTROM, KE MILLER, CF MCCAFFREY, KJW AF HOOK, SJ KARLSTROM, KE MILLER, CF MCCAFFREY, KJW TI MAPPING THE PIUTE MOUNTAINS, CALIFORNIA, WITH THERMAL INFRARED MULTISPECTRAL SCANNER (TIMS) IMAGES SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID MOJAVE DESERT REGION; METAMORPHOSED PALEOZOIC STRATA; SOUTHEASTERN CALIFORNIA; DEATH-VALLEY; AREA; PLUTONISM; EXTENSION; EVOLUTION; ARIZONA AB Thermal infrared multispectral scanner (TIMS) data were acquired in 1990 over the Piute Mountains, California, to evaluate their usefulness for lithologic mapping in an area of metamorphosed, structurally complex, igneous and sedimentary rocks. The data were calibrated and atmospherically corrected, and emissivity variations in the form of alpha residuals were extracted from which color composite images were made. There was an excellent visual correlation between the units revealed in the color composite image and the lithologic units mapped in the eastern side of the area. It was also possible to correct, improve, and extend the recent map. For example, several areas mapped as granodioritic gneiss had TIMS alpha residual spectra consistent with mafic rocks and were subsequently mapped as amphibolite. The presence of a swarm of mafic dikes, of which only a few had previously been identified, was also revealed. The images also showed color variations in granitoid plutons that correlated with compositional variations previously determined by extensive field and geochemical work, The western Piute Mountains is an area that has proven to be especially difficult to map with field and air photographic methods, due to heterogeneous nature of certain units and various levels of desert varnish. The images permitted the extremely heterogeneous Proterozoic schists, gneisses, and granites to be easily mapped because the small-scale compositional variability was averaged to the TIMS pixel size (12 m x 12 m square). Areal measurements from the images show that the Proterozoic rocks in the Piute Mountains consist of granitoids (approximately 50%), biotite gneiss (approximately 15%), pelitic gneiss (approximately 15%), quartzite (approximately 10%), and amphibolite (approximately 10%). TIMS data can dramatically increase the efficiency and the quality of geologic mapping in well-exposed heterogeneous areas with minimal vegetation cover where detailed mapping of lithologic contacts by traditional methods is unusually difficult. C1 UNIV NEW MEXICO, DEPT GEOL, ALBUQUERQUE, NM 87131 USA. VANDERBILT UNIV, DEPT GEOL, NASHVILLE, TN 37235 USA. JOHNS HOPKINS UNIV, DEPT EARTH & PLANETARY SCI, BALTIMORE, MD 21218 USA. RP HOOK, SJ (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. RI McCaffrey, Kenneth/F-2285-2014 OI McCaffrey, Kenneth/0000-0002-9882-1709 NR 38 TC 25 Z9 26 U1 1 U2 3 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 AUG 10 PY 1994 VL 99 IS B8 BP 15605 EP 15622 DI 10.1029/94JB00690 PG 18 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PB520 UT WOS:A1994PB52000036 ER PT J AU LUNDGREN, P GIARDINI, D AF LUNDGREN, P GIARDINI, D TI ISOLATED DEEP EARTHQUAKES AND THE FATE OF SUBDUCTION IN THE MANTLE SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID FOCUS EARTHQUAKES; NORTHWEST PACIFIC; SLAB PENETRATION; ISLAND ARCS; SOURCE PARAMETERS; FOCAL MECHANISMS; DESCENDING SLAB; HOKKAIDO CORNER; PLATE MOTIONS; KAMCHATKA ARC AB The locations of earthquakes with depth in the mantle provide direct evidence of the trajectory and state of stress of subducting lithosphere. The occurrence over the last decade of isolated large deep earthquakes outside the main Wadati-Benioff zones in the Kurile, Izu-Bonin, and Chile deep seismic areas (in addition to the observed flat distributions of deep seismicity beneath the Banda Sea and Fiji Plateau areas and the large number of deep earthquakes located away from the main slab in the Tonga arc) supports recent tomographic and other seismological studies, leading to a reconsideration of slabs as simple planar structures sinking undeformed into the lower mantle. The focal geometries of these isolated earthquakes, which often exhibit near vertical compressional stresses, are distinct from adjacent events in the main Wadati-Benioff zone. They are also different in orientation from events in the deflecting toe of the slab and from the stress orientation expected if the deflected slab acts as a stress guide. These isolated mantle earthquakes are interpreted to take place in subducted lithosphere that has deflected to a horizontal posture at the base of the upper mantle. Conversely, the deep seismicity in the adjacent Wadati-Benioff zone is associated with the deflection of the subducting lithosphere. C1 UNIV ROMA, DIPARTIMENTO GEOL 3, I-00154 ROME, ITALY. RP LUNDGREN, P (reprint author), JET PROP LAB, 4800 OAK GROVE DR, MS 183501, PASADENA, CA 91109 USA. RI Giardini, Domenico/F-5406-2011 NR 60 TC 43 Z9 44 U1 0 U2 5 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 AUG 10 PY 1994 VL 99 IS B8 BP 15833 EP 15842 DI 10.1029/94JB00038 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PB520 UT WOS:A1994PB52000055 ER PT J AU BOZZOLO, G RODRIGUEZ, AM FERRANTE, J AF BOZZOLO, G RODRIGUEZ, AM FERRANTE, J TI MULTILAYER RELAXATION AND SURFACE ENERGIES OF METALLIC SURFACES SO SURFACE SCIENCE LA English DT Article ID EQUIVALENT-CRYSTAL THEORY; ELECTRON-DIFFRACTION; LATTICE-RELAXATION; DEFECTS; SPECTRA; FCC AB The perpendicular and parallel multilayer relaxations of fcc (210) surfaces are studied using equivalent crystal theory (ECT). A comparison with experimental and theoretical results is made for Al(210). The effect of uncertainties in the input parameters on the magnitudes and ordering of surface relaxations for this semiempirical method is estimated. A new measure of surface roughness is proposed. Predictions for the multilayer relaxations and surface energies of the (210) face of Cu and Ni are also included. C1 NATL UNIV LA PLATA,DIPARTIMENTO FIS,RA-1900 LA PLATA,ARGENTINA. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BOZZOLO, G (reprint author), ANALEX CORP,3001 AEROSP PKWY,BROOKPARK,OH 44142, USA. NR 37 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD AUG 10 PY 1994 VL 315 IS 1-2 BP 204 EP 214 DI 10.1016/0039-6028(94)90555-X PG 11 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA PC311 UT WOS:A1994PC31100034 ER PT J AU ZARETSKY, EV AF ZARETSKY, EV TI DESIGN FOR LIFE, PLAN FOR DEATH SO MACHINE DESIGN LA English DT Article RP ZARETSKY, EV (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU PENTON PUBL INC PI CLEVELAND PA 1100 SUPERIOR AVE, CLEVELAND, OH 44114 SN 0024-9114 J9 MACH DES JI Mach. Des. PD AUG 8 PY 1994 VL 66 IS 15 BP 57 EP 59 PG 3 WC Engineering, Mechanical SC Engineering GA PA997 UT WOS:A1994PA99700018 ER PT J AU DAVIS, DAR SMITH, FT AF DAVIS, DAR SMITH, FT TI INFLUENCE OF CROSS-FLOW ON NONLINEAR TOLLMIEN-SCHLICHTING VORTEX INTERACTION SO PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article ID BOUNDARY-LAYER-TRANSITION; TAYLOR-GORTLER VORTICES; WAVE INTERACTIONS; CHANNEL FLOWS AB The transition of an incompressible three-dimensional boundary layer with strong cross-flow is considered theoretically and computationally in the context of vortex/wave interactions. Specifically the work centres on two lower-branch Tollmien-Schlichting waves which mutually interact nonlinearly to induce a longitudinal vortex flow. The vortex motion in turn gives rise to significant wave modulation via wall-shear forcing. The characteristic Reynolds number is large and, as a consequence, the waves' and the vortex motion are governed primarily by triple-deck theory. The nonlinear interaction is captured by a viscous partial-differential system for the vortex coupled with a pair of amplitude equations for each wave pressure. Following analysis and computation over a wide range of parameters, three distinct responses are found to emerge in the nonlinear behaviour of the flow solution downstream: an algebraic finite-distance singularity, far-downstream saturation or far-downstream wave decay leaving pure vortex flow. These depend on the input conditions, the wave angles and the size of the cross flow. C1 UNIV LONDON UNIV COLL,DEPT MATH,LONDON WC1E 6BT,ENGLAND. RP DAVIS, DAR (reprint author), NASA,LEWIS RES CTR,INST COMPUTAT MECH PROP,CLEVELAND,OH 44135, USA. NR 28 TC 8 Z9 8 U1 0 U2 1 PU ROYAL SOC LONDON PI LONDON PA 6 CARLTON HOUSE TERRACE, LONDON, ENGLAND SW1Y 5AG SN 1364-5021 J9 P ROY SOC LOND A MAT JI Proc. R. Soc. London Ser. A-Math. Phys. Eng. Sci. PD AUG 8 PY 1994 VL 446 IS 1927 BP 319 EP 340 DI 10.1098/rspa.1994.0107 PG 22 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PB717 UT WOS:A1994PB71700007 ER PT J AU MAITRE, P BAUSCHLICHER, CW AF MAITRE, P BAUSCHLICHER, CW TI THEORETICAL-STUDY OF THE LOW-LYING STATES OF MGN2+ SO CHEMICAL PHYSICS LETTERS LA English DT Article ID MOLECULAR WAVE-FUNCTIONS; ANO BASIS-SETS; PHOTODISSOCIATION SPECTROSCOPY; ROW ATOMS; SPECTRA AB The structure, harmonic frequencies and binding energies of the low-lying states of MgN2+ have been computed at the multi-reference configuration interaction level of theory. The charge-quadrupole interaction results in a linear 2SIGMA+ ground state of MgN2+, as expected. The excited states can arise from either the interaction of the 2P state of Mg+ with N2 or from a charge transfer 'state' with Mg2+N2- bonding character. The lowest lying excited state, B-2(2), is a mixture of these two mechanisms, which results in a C2v geometry with the Mg atom sitting at the N2 bond midpoint. A small barrier in the bending potential exists between this state and the 2PI state, which is the lowest lying linear excited state. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RI Maitre, Philippe/C-1022-2013 OI Maitre, Philippe/0000-0003-2924-1054 NR 19 TC 24 Z9 24 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD AUG 5 PY 1994 VL 225 IS 4-6 BP 467 EP 472 DI 10.1016/0009-2614(94)87113-2 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PB644 UT WOS:A1994PB64400030 ER PT J AU SIMONS, RN TAUB, SR LEE, RQ YOUNG, PG AF SIMONS, RN TAUB, SR LEE, RQ YOUNG, PG TI MICROWAVE CHARACTERIZATION OF SLOT LINE AND COPLANAR STRIP LINE ON HIGH-RESISTIVITY SILICON FOR A SLOT ANTENNA FEED NETWORK SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE SLOTLINE; COPLANAR STRIPLINE; SLOT ANTENNA; HIGH-RESISTIVITY SILICON SUBSTRATE AB This article presents the effective dielectric constant (epsilon(eff)) and attenuation constant (alpha) of an unshielded slot line and a coplanar strip line on a high-resistivity (5000-10,000 OMEGA-cm) silicon wafer. The epsilon(eff) (dc to 40 GHz) and a (dc to 26.5 GHz) in each case are determined from the measured resonant frequencies and insertion loss of a ring resonator. The measurements are carried out at room temperature. No dc bias is applied to the transmission lines. The attenuation for slot line and coplanar stripline on silicon are compared with microstrip line and coplanar waveguide on other semiconductor substrate materials. Lastly, a microstrip-to-slot-line transition and its use in a feed network for linearly tapered slot antennas is demonstrated. (C) 1994 John Wiley & Sons. Inc. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,MAIL STOP 54-5,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 0 TC 3 Z9 3 U1 0 U2 1 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 AUG 5 PY 1994 VL 7 IS 11 BP 489 EP 494 DI 10.1002/mop.4650071104 PG 6 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA NX457 UT WOS:A1994NX45700003 ER PT J AU JENNISKENS, P BLAKE, DF AF JENNISKENS, P BLAKE, DF TI STRUCTURAL TRANSITIONS IN AMORPHOUS WATER ICE AND ASTROPHYSICAL IMPLICATIONS SO SCIENCE LA English DT Article ID SOLID WATER; INTERSTELLAR GRAINS; LIQUID WATER; VAPOR; PRESSURE; AMORPHIZATION; DIFFRACTION; BEHAVIOR; REGION; IH AB Selected area electron diffraction is used to monitor structural changes of vapor-deposited water ice in vacuum during warm-up from 15 to 188 K. A progression of three amorphous forms of water ice is found with well-defined transitions. The formation of a high-density amorphous form (I(a)h) at 15 K is confirmed, and the transition to the more familiar low-density form (I(a)l) occurs gradually over the range 38 to 68 K. At 131 K, the ice transforms into a third amorphous form (I(a)r), which precedes the crystallization of cubic ice (I-c) and coexists metastably with I-c from 148 K until at least 188 K. These structural transformations of amorphous water ice can be used to explain hitherto anomalous properties of astrophysical ices. The structural transition from I(a)h to I(a)l is responsible for the diffusion and recombination of radicals in ultraviolet-photolyzed interstellar ices at low temperatures. The occurrence and persistence of I(a)r explains anomalous gas retention and gas release from water-rich ices at temperatures above 150 K. RP JENNISKENS, P (reprint author), NASA,AMES RES CTR,SPACE SCI MICROSCOPY LAB,MAIL STOP 239-4,MOFFETT FIELD,CA 94035, USA. NR 45 TC 312 Z9 312 U1 0 U2 47 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD AUG 5 PY 1994 VL 265 IS 5173 BP 753 EP 756 DI 10.1126/science.11539186 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PA372 UT WOS:A1994PA37200024 PM 11539186 ER PT J AU JAKOSKY, BM JONES, JH AF JAKOSKY, BM JONES, JH TI PLANETARY SCIENCE - EVOLUTION OF WATER ON MARS SO NATURE LA English DT Editorial Material ID D/H C1 UNIV COLORADO, DEPT GEOL SCI, BOULDER, CO 80309 USA. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP UNIV COLORADO, ATMOSPHER & SPACE PHYS LAB, BOULDER, CO 80309 USA. NR 16 TC 30 Z9 30 U1 0 U2 2 PU NATURE PUBLISHING GROUP PI LONDON PA MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND SN 0028-0836 EI 1476-4687 J9 NATURE JI Nature PD AUG 4 PY 1994 VL 370 IS 6488 BP 328 EP 329 DI 10.1038/370328a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA PA304 UT WOS:A1994PA30400030 ER PT J AU REDA, DC MURATORE, JJ AF REDA, DC MURATORE, JJ TI MEASUREMENT OF SURFACE SHEAR-STRESS VECTORS USING LIQUID-CRYSTAL COATINGS SO AIAA JOURNAL LA English DT Article AB Under normal white light illumination and oblique observation, liquid crystal coating (LCC) color-change response to shear depends on both shear stress magnitude as well as the direction of the applied shear relative to the observer's line of sight. These color-change responses were quantified by subjecting a LCC to a wall-jet shear flow and measuring scattered-light spectra using a fiber optic probe and spectrophotometer. At any fixed shear stress magnitude, the maximum color change was measured when the shear vector was aligned with and directed away from the observer; changes in the relative in-plane view angle to either side of this vector/observer aligned position resulted in symmetric Gaussian reductions in measured color change. Based on these results, a surface shear stress vector measurement methodology, involving multiple oblique-view observations of the test surface, was formulated. Under present test conditions, the measurement resolution of this technique was found to be +/-1 deg for vector orientations and +/-5% for vector magnitudes. An approach to extend the present methodology to full-surface applications is proposed. RP REDA, DC (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 21 TC 23 Z9 23 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 AUG PY 1994 VL 32 IS 8 BP 1576 EP 1582 DI 10.2514/3.12146 PG 7 WC Engineering, Aerospace SC Engineering GA NZ342 UT WOS:A1994NZ34200003 ER PT J AU MENTER, FR AF MENTER, FR TI 2-EQUATION EDDY-VISCOSITY TURBULENCE MODELS FOR ENGINEERING APPLICATIONS SO AIAA JOURNAL LA English DT Article ID ADVERSE PRESSURE-GRADIENT; BOUNDARY-LAYERS; FLOW AB Two new two-equation eddy-viscosity turbulence models will be presented. They combine different elements of existing models that are considered superior to their alternatives. The first model, referred to as the baseline (BSL) model, utilizes the original k-omega model of Wilcox in the inner region of the boundary layer and switches to the standard k-epsilon model in the outer region and in free shear flows. It has a performance similar to the Wilcox model, but avoids that model's strong freestream sensitivity. The second model results from a modification to the definition of the eddy-viscosity in the BSL model, which accounts for the effect of the transport of the principal turbulent shear stress. The new model is called the shear-stress transport-model and leads to major improvements in the prediction of adverse pressure gradient flows. RP MENTER, FR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 24 TC 3535 Z9 3959 U1 24 U2 238 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 AUG PY 1994 VL 32 IS 8 BP 1598 EP 1605 DI 10.2514/3.12149 PG 8 WC Engineering, Aerospace SC Engineering GA NZ342 UT WOS:A1994NZ34200006 ER PT J AU BIKLE, DD HARRIS, J HALLORAN, BP ROBERTS, CT LEROITH, D MOREYHOLTON, E AF BIKLE, DD HARRIS, J HALLORAN, BP ROBERTS, CT LEROITH, D MOREYHOLTON, E TI EXPRESSION OF THE GENES FOR INSULIN-LIKE GROWTH-FACTORS AND THEIR RECEPTORS IN BONE DURING SKELETAL GROWTH SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE DEVELOPMENT; AGE; FETUS; TIBIA; POSTNATAL ID I IGF-I; MESSENGER-RIBONUCLEIC-ACID; OSTEOBLAST-ENRICHED CULTURES; FETAL-RAT BONE; PARATHYROID-HORMONE; SOMATOMEDIN-C; DEVELOPMENTAL EXPRESSION; TISSUES; INVIVO; LIVER AB Insulin-like growth factors (IGF) are important regulators of skeletal growth. To determine whether the capacity to produce and respond to these growth factors changes during skeletal development, we measured the protein and mRNA levels for IGF-I, IGF-II, and their receptors (IGF-IR and IGF-IIR, respectively) in the tibia and femur of rats before and up to 28 mo after birth. The mRNA levels remained high during fetal development but fell after birth, reaching a nadir by 3-6 wk. This fall was most pronounced for IGF-II and IGF-IIR mRNA,4 and least pronounced for IGF-I mRNA. However, after 6 wk, both IGF-I and IGF-IR mRNA levels recovered toward the levels observed at birth. In the prenatal bones, the signals for the mRNAs of IGF-II and IGF-IIR were stronger than the signals for the mRNAs of IGF-I and IGF-IR, although the content of IGF-I was three- to fivefold greater than that of IGF-II. IGF-II levels fell postnatally, whereas the IGF-I content rose after birth such that the ratio IGF-I/IGF-II continued to increase with age. We conclude that, during development, rat bone changes its capacity to produce and respond to IGFs with a progressive trend toward the dominance of IGF-I. C1 NIH,DIABET BRANCH,BETHESDA,MD 20892. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF SAN FRANCISCO,DEPT MED,SAN FRANCISCO,CA 94121. NR 29 TC 10 Z9 10 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD AUG PY 1994 VL 267 IS 2 BP E278 EP E286 PN 1 PG 9 WC Physiology SC Physiology GA PC439 UT WOS:A1994PC43900050 PM 8074208 ER PT J AU LINDERMAN, JK GOSSELINK, KL BOOTH, FW MUKKU, VR GRINDELAND, RE AF LINDERMAN, JK GOSSELINK, KL BOOTH, FW MUKKU, VR GRINDELAND, RE TI RESISTANCE EXERCISE AND GROWTH-HORMONE AS COUNTERMEASURES FOR SKELETAL-MUSCLE ATROPHY IN HINDLIMB-SUSPENDED RATS SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE PROTEIN SYNTHESIS; HINDLIMB SUSPENSION ID INTERSTITIAL FLUID VOLUME; SOLEUS MUSCLE; PROTEIN-METABOLISM; ANABOLIC-STEROIDS; MESSENGER-RNA; SUSPENSION; SPACEFLIGHT; TURNOVER; IMMOBILIZATION; HYPOKINESIA AB Unweighting of rat hindlimb muscles results in skeletal muscle atrophy, decreased protein synthesis, and reduced growth hormone (GH) secretion. Resistance exercise (ladder climbing) and GH treatment partially attenuate skeletal muscle atrophy in hypophysectomized hindlimb-suspended rats. It was hypothesized that a combination of multiple bouts of daily resistance exercise and GH (1 mg.kg(-1).day(-1)) would prevent skeletal muscle atrophy in growing nonhypophysectomized hindlimb-suspended rats. Hindlimb suspension decreased the absolute (mg/pair) and relative (mg/100 g body wt) weights of the soleus, a slow-twitch plantar flexor, by 30 and 21%, respectively, and the absolute and relative weights of the gastrocnemius, a predominantly fast-twitch plantar flexor, by 20 and 11%, respectively (P < 0.05). Exercise did not increase soleus mass but attenuated loss of relative wet weight in the gastrocnemius muscles of hindlimb-suspended rats (P < 0.05). Hindlimb suspension decreased gastrocnemius myofibrillar protein content and synthesis (mg/day) by 26 and 64%, respectively (P < 0.05). The combination of exercise and GH attenuated loss of gastrocnemius myofibrillar protein content and synthesis by 70 and 23%, respectively (P < 0.05). Results of the present investigation indicate that a combination of GH and resistance exercise attenuates atrophy of unweighted fast-twitch skeletal muscles. C1 GENENTECH INC,S SAN FRANCISCO,CA 94080. UNIV TEXAS,SCH MED,DEPT PHYSIOL & CELL BIOL,HOUSTON,TX 77225. RP LINDERMAN, JK (reprint author), NASA,AMES RES CTR,DIV LIFE SCI,239-11,MOFFETT FIELD,CA 94035, USA. NR 34 TC 49 Z9 49 U1 0 U2 2 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD AUG PY 1994 VL 267 IS 2 BP R365 EP R371 PN 2 PG 7 WC Physiology SC Physiology GA PC441 UT WOS:A1994PC44100058 PM 8067444 ER PT J AU ROBERTSON, D CONVERTINO, VA VERNIKOS, J AF ROBERTSON, D CONVERTINO, VA VERNIKOS, J TI THE SYMPATHETIC NERVOUS-SYSTEM AND THE PHYSIOLOGICAL CONSEQUENCES OF SPACEFLIGHT - A HYPOTHESIS SO AMERICAN JOURNAL OF THE MEDICAL SCIENCES LA English DT Review DE AUTONOMIC REGULATION; SPACE PHYSIOLOGY; ORTHOSTATIC HYPOTENSION; HYPOVOLEMIA; ADRENOCEPTORS; ANEMIA ID BETA-HYDROXYLASE DEFICIENCY; DOWN BED REST; ORTHOSTATIC HYPOTENSION; SPACE-FLIGHT; RESPONSES; DOPAMINE; WEIGHTLESSNESS; CATECHOLAMINES; NORADRENALINE AB Many of the physiologic consequences of weightlessness and the cardiovascular abnormalities on return from space could be due, at least in part, to alterations in the regulation of the autonomic nervous system. In this article, the authors review the rationale and evidence for an autonomic mediation of diverse changes that occur with spaceflight, including the anemia and hypovolemia of weightlessness and the tachycardia and orthostatic intolerance on return from space. This hypothesis is supported by studies of two groups of persons known to have low catecholamine levels: persons subjected to prolonged bedrest and persons with syndromes characterized by low circulating catecholamines (Bradbury-Eggleston syndrome and dopamine beta-hydroxylase deficiency). Both groups exhibit the symptoms mentioned. The increasing evidence that autonomic mechanisms underlie many of the physiologic consequences of weightlessness suggests that new pharmacologic approaches (such as administration of beta-blockers and/or sympathomimetic amines) based on these findings may attenuate these unwanted effects. C1 LAB AEROSP CARDIOVASC RES,BROOKS AFB,TX. NASA HEADQUARTERS,DIV LIFE & BIOMED SCI & APPLICAT,WASHINGTON,DC 20546. RP ROBERTSON, D (reprint author), VANDERBILT UNIV,CTR SPACE PHYSIOL & MED,GEN CLIN RES CTR,AA 3228 MCN,NASHVILLE,TN 37232, USA. FU NCRR NIH HHS [RR00095]; NHLBI NIH HHS [HL14192, HL44589] NR 47 TC 69 Z9 70 U1 0 U2 3 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0002-9629 J9 AM J MED SCI JI Am. J. Med. Sci. PD AUG PY 1994 VL 308 IS 2 BP 126 EP 132 DI 10.1097/00000441-199408000-00014 PG 7 WC Medicine, General & Internal SC General & Internal Medicine GA PA658 UT WOS:A1994PA65800014 PM 8042655 ER PT J AU EVANS, BR MARGALIT, R WOODWARD, J AF EVANS, BR MARGALIT, R WOODWARD, J TI VERATRYL ALCOHOL OXIDASE ACTIVITY OF A CHEMICALLY-MODIFIED CELLULASE PROTEIN SO ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS LA English DT Article ID SPERM WHALE MYOGLOBIN; LIGNIN-PEROXIDASE; PHANEROCHAETE-CHRYSOSPORIUM; TRICHODERMA-REESEI; ELECTRON-TRANSFER; CATALYTIC ACTIVITY; FUNGAL CELLULASES; CYTOCHROME-C; OXALIC-ACID; OXIDATION AB A cellulase, cellobiohydrolase I (CBH I) from Trichoderma reesei was chemically modified by covalent attachment of pentaammine ruthenium (III) without loss in hydrolytic activity. Data suggest that such a modification endowed CBH I with oxidoreductase activity. The modified enzyme was able to carry out hydrogen peroxide-dependent oxidation of veratryl alcohol, a substrate for lignin peroxidase, at a rate of 0.148 mu mol substrate oxidized min(-1) mu mol(-1) enzyme. The effects of pH, temperature, and substrate concentration on the oxidation reaction were examined. The optimal temperature was determined to be 45 degrees C, and the optimal pH was 4.3. The K-m and V-max for veratryl alcohol were determined to be 3.519 mM and 52.27 mu M min(-1), respectively. Tartrate at concentrations as low as 0.10 mM was found to inhibit the reaction. (C) 1994 Academic Press, Inc. C1 OAK RIDGE NATL LAB,DIV CHEM TECHNOL,OAK RIDGE,TN 37831. CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 36 TC 12 Z9 12 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0003-9861 J9 ARCH BIOCHEM BIOPHYS JI Arch. Biochem. Biophys. PD AUG 1 PY 1994 VL 312 IS 2 BP 459 EP 466 DI 10.1006/abbi.1994.1332 PG 8 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA NX805 UT WOS:A1994NX80500018 PM 8037459 ER PT J AU SHORE, SN AUFDENBERG, JP MICHALITSIANOS, AG AF SHORE, SN AUFDENBERG, JP MICHALITSIANOS, AG TI A MODEL FOR THE SPECTROSCOPIC VARIATIONS OF THE PECULIAR SYMBIOTIC STAR MWC-560 SO ASTRONOMICAL JOURNAL LA English DT Article ID OBJECT MWC-560; MWC560 AB In this note, we show that the ultraviolet and optical spectroscopic variability of this unique symbiotic star can be understood in terms of a time variable collimated stellar wind with a rapid acceleration near the source. Using the radial velocities observed during the ultraviolet bright phase, we find that a variation in the mass loss rate of a factor of ten can explain the ultraviolet spectral changes. The acceleration is far faster than normally observed in radiatively driven stellar winds and may be due to mechanical driving of the outflow from the disk. C1 UNIV TOLEDO, DEPT PHYS & ASTRON, TOLEDO, OH 43606 USA. NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RP INDIANA UNIV, DEPT PHYS & ASTRON, 1700 MISHAWAKA AVE, S BEND, IN 46634 USA. NR 24 TC 17 Z9 17 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-6256 EI 1538-3881 J9 ASTRON J JI Astron. J. PD AUG PY 1994 VL 108 IS 2 BP 671 EP 677 DI 10.1086/117103 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ059 UT WOS:A1994NZ05900030 ER PT J AU FEKEL, FC HENRY, GW HAMPTON, ML FRIED, R MORTON, MD AF FEKEL, FC HENRY, GW HAMPTON, ML FRIED, R MORTON, MD TI CHROMOSPHERICALLY ACTIVE STARS .12. ADS 11060-C - A DOUBLE-LINED K-DWARF BINARY IN A QUINTUPLE SYSTEM SO ASTRONOMICAL JOURNAL LA English DT Article ID SPECTROSCOPIC-VISUAL TRIPLE; LITHIUM ABUNDANCES; MAIN-SEQUENCE; CATALOG; EVOLUTION; PLEIADES; SEPARATIONS; PHOTOMETRY; HD-165590; EDITION AB ADS 11060 C is a double lined spectroscopic binary with a period of 25.7631 days and an eccentricity of 0.565. Spectral types of two stars are estimated as K7 V M0 V with a magnitude difference of about 0.55 mag in V. The stars appear to be somewhat metal rich with respect to the Sun. Despite the relatively large masses of 0.53 and 0.51 M., our photometric observations find no evidence for eclipses and we estimate an inclination of 77-degrees +/- 11-degrees. ADS 11060 C is, however, photometrically variable with a period of 9 +/- 1 day and an amplitude of 0.05 mag in V. Thus, it is a newly identified BY Draconis variable. The center-of-mass velocity of ADS 11060 C and an estimated parallax of 0.030'' support its physical association with ADS 11060 AB, making this a quintuple system. The projected separation of the AB-C system is nearly 1200 AU. Although the log lithium abundances of the two components of ADS 11060 C are only upper limits, less-than-or-equal-to 0.14, lithium abundances of the AB-C components appear to be consistent with those of similar stars in the alpha Persei and Pleiades clusters, suggesting an age of about 70 Myr for ADS 11060 AB-C. The system is a possible member of the Pleiades moving group. Listed as an optical counterpart to a source in the ROSAT Wide Field Camera extreme-ultraviolet bright source catalog, both ADS 11060 AB and C may contribute to the observed flux. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. BRAESIDE OBSERV,FLAGSTAFF,AZ 86002. VANDERBILT UNIV,DEPT PHYS & ASTRON,NASHVILLE,TN 37235. RP FEKEL, FC (reprint author), TENNESSEE STATE UNIV,CTR EXCELLENCE INFORMAT SYST,330 10TH AVE,NASHVILLE,TN 37203, USA. NR 52 TC 7 Z9 7 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0004-6256 J9 ASTRON J JI Astron. J. PD AUG PY 1994 VL 108 IS 2 BP 694 EP 700 DI 10.1086/117106 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ059 UT WOS:A1994NZ05900033 ER PT J AU WILLIAMS, JG AF WILLIAMS, JG TI CONTRIBUTIONS TO THE EARTHS OBLIQUITY RATE, PRECESSION, AND NUTATION SO ASTRONOMICAL JOURNAL LA English DT Article ID INNER CORE DYNAMICS; LONG-TERM CHANGES; IAU 1976 SYSTEM; FORCED NUTATIONS; RIGID-EARTH; NUMERICAL DETERMINATION; ASTRONOMICAL CONSTANTS; TEMPORAL VARIATIONS; LUNI-SOLAR; ROTATION AB The precession and nutation of the Earth's equator arise from solar, lunar, and planetary torques on the oblate Earth. The mean lunar orbit plane is nearly coincident with the ecliptic plane. A small tilt out of the ecliptic is caused by planetary perturbations and the Earth's gravitational harmonic J2. These planetary perturbations on the lunar orbit result in torques on the oblate Earth which contribute to precession, obliquity rate, and nutation while the J2 perturbations contribute to precession and nutation. Small additional contributions to the secular rates arise from tidal effects and planetary torques on the Earth's bulge. The total correction to the obliquity rate is -0.024''/century, it is an observable motion in space (the much larger conventional obliquity rate is wholly from the motion of the ecliptic, not the equator), and it is not present in the IAU-adopted expressions for the orientation of the Earth's equator. The J2 effects have generally been allowed for in past nutation theories and some precession theories. For the planetary effect, the contributions to the 18.6 yr nutation are -0.03 mas (milliarcseconds) for the in-phase DELTApsi plus out-of-phase contributions of 0.14 mas in DELTApsi and -0.03 mas in DELTAepsilon. The latter terms demonstrate that out-of-phase contributions can arise by means other than dissipation. The sum of the contributions to the precession rate is considered and the inferred value of the moment of inertia combination (C -A)/C, which is used to scale the coefficients in the nutation series, is evaluated. Using an updated value for the precession rate, the rigid body (C -A)IC =0.003 273 763 4 which, in combination with a satellite-derived J2, gives a normalized polar moment of inertia C/MR2=0.330 700 7. The planetary contributions to the precession and obliquity rates are not constant for long times causing accelerations in both quantities. Acceleration in precession also arises from tides and changing J2. Contributions from the improved theory, masses, ecliptic motion, and measured values of the precession rate and obliquity are combined to give expressions (polynomials in time) for precession, obliquity, and Greenwich Mean Sidereal Time. RP WILLIAMS, JG (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 61 TC 91 Z9 94 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 AUG PY 1994 VL 108 IS 2 BP 711 EP 724 DI 10.1086/117108 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ059 UT WOS:A1994NZ05900035 ER PT J AU SHEBALIN, JV AF SHEBALIN, JV TI NUMERICAL-SIMULATION OF 3-DIMENSIONAL SELF-GRAVITATING FLOW SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, FORMATION; ISM, CLOUDS; ISM, KINEMATICS AND DYNAMICS; METHODS, NUMERICAL ID MOLECULAR CLOUDS; JEANS COLLAPSE; TURBULENCE; STABILITY AB The three-dimensional flow of a self-gravitating fluid is numerically simulated using a Fourier pseudospectral method with a logarithmic variable formulation. Two cases with zero total angular momentum are studied in detail, a 32(3) simulation (Run A) and a 64(3) simulation (Run B). Other than the grid size, the primary differences between the two cases are that Run A modelled atomic hydrogen and had considerably more compressible motion initially than Run B, which modelled molecular hydrogen. ('Compressible motion' is that part of the velocity which has zero curl, but non-zero divergence.) The numerical results indicate that gravitational collapse can proceed in a variety of ways. In Run A, collapse led to an elongated tube-like structure, while in Run B, collapse led to a flatter, disk-like structure. RP SHEBALIN, JV (reprint author), NASA, LANGLEY RES CTR, MAIL STOP 156, HAMPTON, VA 23665 USA. NR 15 TC 0 Z9 0 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD AUG PY 1994 VL 288 IS 1 BP 150 EP 154 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA472 UT WOS:A1994PA47200018 ER PT J AU WINTERS, JM DOMINIK, C SEDLMAYR, E AF WINTERS, JM DOMINIK, C SEDLMAYR, E TI THEORETICAL SPECTRA OF CIRCUMSTELLAR DUST SHELLS AROUND CARBON-RICH ASYMPTOTIC GIANT BRANCH STARS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, CARBON; CIRCUMSTELLAR MATTER; STARS, INDIVIDUAL, IRC+10216; STARS, MASS-LOSS; STARS, AGB ID MASS-LOSS RATES; EVOLVED STARS; STELLAR WINDS; DRIVEN WINDS; IRC +10216; RED GIANTS; C-STARS; RADIATION PRESSURE; GRAIN FORMATION; LOSS MECHANISMS AB Realistic modelling of circumstellar dust shells around evolved stars has to include a physical treatment of the interaction among hydrodynamics, thermodynamics, radiative transfer, chemistry and dust formation and -growth. A self-consistent solution of this problem is presented in the case of stationary, spherical symmetric dust-driven winds. The resulting shell structure and the mass-loss rate are completely determined by the three fundamental stellar parameters stellar mass M*, stellar luminosity L* and effective temperature T(eff) and by the element abundances epsilon(i). A detailed calculation of the transport coefficients of the dust component by means of the particle size distribution function and the solution of the non-grey radiative transfer problem provide realistic synthetic spectra of the dust shell models. We discuss the dependence of the resulting spectra on the stellar parameters in terms of infrared two colour diagrams. Application of these model calculations to the prominent infrared object IRC +10216 yields best agreement with the observed spectrum and the visibility data at maximum light for the stellar parameters M* = 0.7M., L* = 2.4 . 10(4) L., T* = 2010K and a carbon to oxygen ratio of epsilon(C)/epsilon(O) = 1.40, which corresponds to a mass-loss rate of M = 8 . 10(-5) M.yr-1. In this model only amorphous carbon grains are considered as the main opacity source. From this model a distance to IRC + 10216 of d = 170pc is deduced. The total mass contained in the circumstellar dust shell implies an initial main sequence mass Of M(ZAMS) greater-than-or-equal-to 1.3M. for IRC+10216. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP WINTERS, JM (reprint author), TECH UNIV BERLIN, INST ASTRON & ASTROPHYS, PN 8-1, HARDENBERGSTR 36, D-10623 BERLIN, GERMANY. NR 73 TC 63 Z9 63 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD AUG PY 1994 VL 288 IS 1 BP 255 EP 272 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA472 UT WOS:A1994PA47200028 ER PT J AU HENNING, T MARTIN, K REIMANN, HG LAUNHARDT, R LEISAWITZ, D ZINNECKER, H AF HENNING, T MARTIN, K REIMANN, HG LAUNHARDT, R LEISAWITZ, D ZINNECKER, H TI MULTIWAVELENGTH STUDY OF NGC-281-A SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE INTERSTELLAR MEDIUM, INDIVIDUAL OBJECTS, NGC-281A CLOUD; INTERSTELLAR MEDIUM, CLOUDS; STARS, FORMATION; DUST; RADIO LINES, ISM ID MOLECULAR CLOUDS; UVBY PHOTOMETRY; STELLAR OBJECTS; STANDARD STARS; CEPHEUS CLOUDS; OPEN CLUSTERS; ORION NEBULA; AMMONIA; CATALOG; YOUNG AB We present a study of the molecular cloud NGC 281 A and the associated compact and young star cluster NGC 281 (AS 179). Optical photometry leads to a new distance of 3500 pc for the star cluster which is in good agreement with the kinematical distance of the adjacent molecular cloud NGC 281 A. The exciting star HD 5005 of the optical nebulosity is a Trapezium system with O6 III as photometric spectral type for the component HD 5005 AB. For the age of the star cluster we estimated a value of about 3.10(6) yr. The (CO)-C-12(2-->1), (CO)-C-13(2-->1), and (CO)-C-12(3-->2) emission shows that the molecular cloud NGC 281 A consists of two cloud fragments. The western fragment is more compact and massive than the eastern fragment and contains an NH3 Core. This core is associated with the IRAS source 00494+5617, an H2O maser, and 1.3 millimetre dust continuum radiation. Both cloud fragments contain altogether 22 IRAS point sources which mostly share the properties of young stellar objects. They have luminosities between 150 and 8800 L.. The maxima of the 60 and 100 mum HIRES maps correspond to the maxima of the (CO)-C-12(3-->2) emission. The NGC 281 A region shares many properties with the Orion Trapezium-BN/KL region the main differences being a larger separation between the cluster centroid and the new site of star formation as well as a lower mass and luminosity of the molecular cloud and the infrared cluster. C1 UNIV JENA, INST ASTROPHYS, D-07740 JENA, GERMANY. UNIV STERNWARTE, D-07740 JENA, GERMANY. UNIV WURZBURG, INST ASTRON & ASTROPHYS, D-97074 WURZBURG, GERMANY. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP HENNING, T (reprint author), MAX PLANCK GESELL, AG STAUB STERNENTSTEHUNGSGEBIETEN, SCHILLERGASSCHEN 2-3, D-07745 JENA, GERMANY. NR 39 TC 17 Z9 18 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD AUG PY 1994 VL 288 IS 1 BP 282 EP 292 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA472 UT WOS:A1994PA47200030 ER PT J AU BRINKMANN, W MARASCHI, L TREVES, A URRY, CM WARWICK, R SIEBERT, J WAGNER, S EDELSON, R FINK, H MADEJSKI, G AF BRINKMANN, W MARASCHI, L TREVES, A URRY, CM WARWICK, R SIEBERT, J WAGNER, S EDELSON, R FINK, H MADEJSKI, G TI MULTIWAVELENGTH MONITORING OF THE BL LACERTAE OBJECT PKS 2155-304 .2. THE ROSAT OBSERVATIONS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE BL LAC OBJECTS; INDIVIDUAL (PKS 2155-304); X-RAYS, GALAXIES; GALAXIES, ACTIVE ID X-RAY VARIABILITY; RELATIVISTIC JETS; INTRADAY VARIABILITY; ABSORPTION FEATURE; LAC OBJECTS; ULTRAVIOLET; PKS-2155-304; EMISSION; MODELS; ACCELERATION AB Extensive ROSAT PSPC observations of the BL Lac object PKS 2155-304 carried out between November 12 and November 15, 1991 revealed the source to be in a bright state with a soft X-ray flux of F(x) (0.1-2.4 keV) almost-equal-to 7 x 10(-10) erg cm-2 s-1. Rapid variations in the X-ray flux of up to 30% within a day were apparent but at the sampling rate of approximately 96 min all of the gross features in the X-ray light curve of this source are time resolved. The soft X-ray flux shows a close correlation with the simultaneous UV flux recorded by IUE although at the beginning and at the end of the PSPC observations there is some deviation from a strict linkage of the X-ray and UV light curves; detailed analysis has shown that the maximal lag of the UV with respect to the soft X-ray flux is less than or similar to 3 hours. The soft X-ray spectrum of PKS 2155-304 remained essentially unchanged over the full duration of the observations. Individual PSPC spectra are consistent with a simple single power-law form with photon index GAMMA approximately -2.65 plus galactic absorption. More complex spectral fits do not improve the quality of the fits significantly. We cannot confirm previous claims of absorption structures at energies approximately 600 eV, but the presence of a narrow absorption trough with width less than or similar to 40 eV or an absorption edge with moderate optical depth (tau approximately 0.25) cannot be ruled out from the ROSAT data. The optical to X-ray spectrum must have a break in the unaccessible energy range between the IUE and ROSAT energy windows. The high energy properties of PKS 2155-304 are consistent with synchrotron emission from a relativistic jet. However, intensity variations without spectral changes are hard to accommodate in existing jet models. More refined, self-consistent time-dependent models are required to explain the details of the physical processes operating in this source. C1 UNIV MILAN, DEPT PHYS, I-20133 MILAN, ITALY. SISSA, ISAS, TRIESTE, ITALY. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. UNIV LEICESTER, DEPT PHYS, LEICESTER LE1 7RH, ENGLAND. LANDESSTERNWARTE HEIDELBERG KONIGSTUHL, D-69117 HEIDELBERG, GERMANY. NASA, GODDARD SPACE FLIGHT CTR, GSFC, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RP BRINKMANN, W (reprint author), MAX PLANCK INST EXTRATERR PHYS, POB 1603, D-85740 GARCHING, GERMANY. RI Urry, Claudia/G-7381-2011 OI Urry, Claudia/0000-0002-0745-9792 NR 58 TC 61 Z9 62 U1 1 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 AUG PY 1994 VL 288 IS 2 BP 433 EP 447 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PB634 UT WOS:A1994PB63400013 ER PT J AU ROQUES, F SICARDY, B FRENCH, RG HUBBARD, WB BARUCCI, A BOUCHET, P BRAHIC, A GEHRELS, JA GEHRELS, T GRENIER, I LEBERTRE, T LECACHEUX, J MAILLARD, JP MCLAREN, RA PERRIER, C VILAS, F WATERWORTH, MD AF ROQUES, F SICARDY, B FRENCH, RG HUBBARD, WB BARUCCI, A BOUCHET, P BRAHIC, A GEHRELS, JA GEHRELS, T GRENIER, I LEBERTRE, T LECACHEUX, J MAILLARD, JP MCLAREN, RA PERRIER, C VILAS, F WATERWORTH, MD TI NEPTUNE UPPER-STRATOSPHERE, 1983-1990 - GROUND-BASED STELLAR OCCULTATION OBSERVATIONS .3. TEMPERATURE PROFILES SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE NEPTUNE; OCCULTATIONS ID JUNE 15 OCCULTATION; UPPER-ATMOSPHERE; SOLAR-CYCLE; URANUS; SYSTEM; OBLATENESS; THERMOSPHERE; TURBULENCE; VOYAGER-2; MODELS AB Nine ground based stellar occultations by Neptune, observed between 1983 and 1990, provide twenty two temperature profiles of the planet upper stratosphere, in the approximately 100-0.01 mubar region, at planetocentric latitudes ranging from approximately 70-degrees-S to approximately 45-degrees-N. The temperatures derived near the 25 mubar level, where the profiles are most reliable, lie in the range 150-200 K. This pressure level is intermediate between those probed by the Voyager radio and UV experiments. Our results confirm the general increase of temperature from the tropopause to the lower thermosphere of Neptune. There is no clear indication of a dependence of the average stratospheric temperature on latitude and/or insolation. On the other hand, there is evidence for a global change in the average Neptunian stratospheric temperature during this seven year time span, which could be correlated with the Lyman-alpha solar emission. One of the observations (June 15, 1983) exhibits absorption-like features. The higher altitude feature (at approximately 10(-2)-10(-3) mubars) could be due to a hot Neptunian thermosphere, or alternatively, to a faint (tau(normal) approximately 10(-5)) haze layer. The lower altitude feature (at approximately 50-100 mubars), is optically thicker (tau(normal) > approximately 10(-2)), and could be connected with the haze layer detected by Voyager at about the same level (Smith et al. 1989, Sci, 246, 1422). The profiles are characterized by strong, local, variations of temperature (DELTAT approximately 30 K), over small vertical distances (approximately 30 km). Assuming that these non-isothermal features are caused by inertia-gravity waves propagating upward in the stratosphere, we have estimated the heating caused by viscous dissipation. Order of magnitude calculations show that this heating rate is dominant, compared to UV and IR absorptions by methane, in the 1-10 mubar region. C1 UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. INST ASTROPHYS, F-75014 PARIS, FRANCE. UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. UNIV PARIS 06, UFR PHYS 924, F-75252 PARIS 05, FRANCE. WELLESLEY COLL, DEPT ASTRON, WELLESLEY, MA 02192 USA. UNIV PARIS 07, UFR PHYS, F-75252 PARIS 05, FRANCE. CERMO, OBSERV GRENOBLE, ASTROPHYS GRP, F-38041 GRENOBLE, FRANCE. QUEENSLAND UNIV TECHNOL, SCH PHYS, BRISBANE, QLD 4001, AUSTRALIA. EUROPEAN SO OBSERV, W-8046 GARCHING, GERMANY. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP ROQUES, F (reprint author), OBSERV PARIS, F-92195 MEUDON, FRANCE. NR 53 TC 29 Z9 29 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD AUG PY 1994 VL 288 IS 3 BP 985 EP 1011 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD321 UT WOS:A1994PD32100035 ER PT J AU NEFF, SG FANELLI, MN ROBERTS, LJ OCONNELL, RW BOHLIN, R ROBERTS, MS SMITH, AM STECHER, TP AF NEFF, SG FANELLI, MN ROBERTS, LJ OCONNELL, RW BOHLIN, R ROBERTS, MS SMITH, AM STECHER, TP TI ULTRAVIOLET IMAGING OF THE AGN PLUS STARBURST GALAXY NGC-1068 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; GALAXIES, INDIVIDUAL (NGC-1068); GALAXIES, NUCLEI; GALAXIES, SEYFERT; ULTRAVIOLET, GALAXIES ID REDSHIFT RADIO GALAXIES; IUE OBSERVATIONS; IONIZED-GAS; DISK; SPECTROPHOTOMETRY; PHOTOMETRY; ALIGNMENT; TELESCOPE; CONTINUUM; EMISSION AB Images of the Seyfert 2 galaxy NGC 1068 were obtained at two ultraviolet wavelengths by the Ultraviolet Imaging Telescope (UIT). These data represent the first detailed UV imagery of a composite (active galactic nucleus + starburst) disk galaxy. NGC 1068 contains multiple components at UV wavelengths: the central active galactic nucleus; a population of very luminous starburst knots; a bright oval inner disk; and a fainter, more circular halo. The most luminous knot, which is located approximately 750 pc from the nucleus at PA 315-degrees, is approximately 80 times the luminosity of 30 Doradus and gives NGC 1068 a ''double nucleus'' appearance in the UV. Significant extended emission is observed throughout the disk, unlike other disk galaxies so far observed in the UV. The radial brightness profile in both UV bandpasses generally follows an exponential decline to approximately 5 kpc. A faint halo extending to approximately 13 kpc is likely to be a galaxian-sized reflection nebula where ambient dust scatters the intense UV continuum from the inner galaxy. UV colors show a striking asymmetric morphology, which is correlated with the observed molecular CO emission. C1 NASA, GODDARD SPACE FLIGHT CTR, HUGHES STX CORP, GREENBELT, MD 20771 USA. UNIV VIRGINIA, DEPT ASTRON, CHARLOTTESVILLE, VA 22903 USA. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. NATL RADIO ASTRON OBSERV, CHARLOTTESVILLE, VA 22903 USA. RP NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, CODE 681, GREENBELT, MD 20771 USA. NR 42 TC 34 Z9 34 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 AUG 1 PY 1994 VL 430 IS 2 BP 545 EP + DI 10.1086/174429 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ043 UT WOS:A1994NZ04300010 ER PT J AU HILL, RS HOME, AT SMITH, AM BRUHWEILER, FC CHENG, KP HINTZEN, PMN OLIVERSEN, RJ AF HILL, RS HOME, AT SMITH, AM BRUHWEILER, FC CHENG, KP HINTZEN, PMN OLIVERSEN, RJ TI STAR-FORMATION IN NGC-4449 - MAMA-DETECTOR UV IMAGERY AND FABRY-PEROT BALMER-LINE IMAGERY SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-4449); GALAXIES, STELLAR CONTENT; STARS, EVOLUTION; STARS, FORMATION; TECHNIQUES, INTERFEROMETRIC; ULTRAVIOLET, STARS ID LARGE MAGELLANIC CLOUD; IRREGULAR GALAXY NGC-4449; H-II-REGIONS; INTER-STELLAR EXTINCTION; IONIZED-GAS; EMISSION; PHOTOMETRY; EVOLUTION; DUST AB Using far-ultraviolet (FUV) and Balmer-line imagery, we investigate the star formation history of 22 large OB complexes in the Magellanic irregular galaxy NGC 4449. The FUV luminosity of NGC 4449 is comparable to those of late-type spirals and is greater than that of the LMC by approximately 2.4 mag, indicating substantial star formation in the last 10(8) yr. FUV data were taken using a sounding-rocket telescope with a Multianode Microchannel Array (MAMA) detector, and Balmer-line data were taken using the Goddard Fabry-Perot Imager. The resulting imagery shows bright, roughly coincident FUV and Halpha sources throughout the extent of the visible galaxy. We model these sources using cluster-evolution codes. Although all sources are a few Myr old, clear age differences are found. In particular, several of the most recently active star formation regions are located together in the galaxy's northern-periphery, which is apparently coincident with a large H I reservoir. The brightest and most massive OB complexes are found along the northeast-southwest surface brightness ridgeline (the ''bar''). Over the entire galaxy, star formation rates are consistent on timescales of 10(6), 10(8), and 10(9) yr, A history of recent star formation is suggested with two main episodes, one predominantly in the bar ending approximately 5 Myr ago, and an ongoing one associated with an observed H I cloud. C1 CATHOLIC UNIV AMER,DEPT PHYS,WASHINGTON,DC 20064. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV NEVADA,DEPT PHYS & ASTRON,LAS VEGAS,NV 89154. RP HILL, RS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,CODE 681,GREENBELT,MD 20771, USA. NR 55 TC 22 Z9 22 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1994 VL 430 IS 2 BP 568 EP & DI 10.1086/174431 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ043 UT WOS:A1994NZ04300012 ER PT J AU SNOWDEN, SL HASINGER, G JAHODA, K LOCKMAN, FJ MCCAMMON, D SANDERS, WT AF SNOWDEN, SL HASINGER, G JAHODA, K LOCKMAN, FJ MCCAMMON, D SANDERS, WT TI SOFT-X-RAY AND HI SURVEYS OF THE LOW NH REGION IN URSA MAJOR SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, HALO; RADIO LINES, ISM; X-RAYS, INTERSTELLAR ID WAY HALO GAS; GALACTIC HALO; DRACO NEBULA; MOLECULAR CLOUD; ROSAT PSPC; DIFFUSE; LIMITS; EMISSION; DENSITY; FLUX AB A region of almost 300 deg2 in Ursa Major around the direction of the lowest neutral hydrogen column density in the sky has been surveyed in the 1/4 keV X-ray band (approximately 0.12-0.284 keV at 10% of the peak response) using the ROSAT PSPC and has been fully mapped in the 21 cm line of neutral hydrogen with an angular resolution of 21' or better. We present maps of these two data sets and an analysis of the spatial correlation between them. Over the entire field, the 1/4 keV band X-ray count rate shows a strong negative correlation with the column density of Galactic neutral hydrogen. We discuss the local, extragalactic, and halo contributions to the observed diffuse X-ray intensity and derive an upper limit to the Galactic X-ray emission originating beyond this H I distribution that is more than a factor of 7 smaller than the inferred flux beyond the Draco nebula, an apparent halo object located approximately 41-degrees away. This implies that while there may be significant amounts of hot gas in the Galactic halo, its properties must vary strongly across the sky. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. NATL RADIO ASTRON OBSERV,GREEN BANK,WV 24944. UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706. RP SNOWDEN, SL (reprint author), MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. RI Snowden, Steven/D-5292-2012; Jahoda, Keith/D-5616-2012 NR 52 TC 64 Z9 64 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1994 VL 430 IS 2 BP 601 EP & DI 10.1086/174434 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ043 UT WOS:A1994NZ04300015 ER PT J AU ZIURYS, LM HOLLIS, JM SNYDER, LE AF ZIURYS, LM HOLLIS, JM SNYDER, LE TI NEW DETECTIONS OF INTERSTELLAR HNO AT 2 AND 1.2 MILLIMETERS - MORE N-O BONDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, MOLECULES; LINE, IDENTIFICATION; RADIO LINES, ISM ID MOLECULAR CLOUD; NITRIC-OXIDE; GAS; EMISSION; REGION; ORION; CHEMISTRY; CONTINUUM; NGC-2024; CORE AB The 2(02)-1(01) and 3(03)-2(02) transitions of HNO at 163 and 244 GHz have been detected toward several molecular clouds. In conjunction with previous measurements of the l(01)-0(00) line at 81 GHz, these observations secure the identification of interstellar HNO. The 2(02)-1(01) transition of this species has been detected toward NGC 2024, Sgr B2 (NW), W51M, and DR 21 (OH), while the 3(03)-2(02) line at 1.2 mm was observed only 2 in NGC 2024. Typical column densities of HNO observed toward these sources are N(tot) approximately 10(12)-10(14) cm-2, corresponding to fractional abundances Of f(HNO) approximately 10(-11) to 10(-10). These values imply NO/HNO ratios of approximately 100-800. Both the HNO fractional abundances and NO/HNO ratios are in reasonable agreement with predictions of ion-molecule-type models of interstellar chemistry, provided early-time calculations are used. Such behavior contrasts with that of other nitrogen compounds, whose observed abundances are best duplicated by steady-state calculations. The chemistries of HNO and NO are thus likely to be related. These observations also suggest that interstellar N-0 bonds may be more common than previously thought. C1 NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,GREENBELT,MD 20771. UNIV ILLINOIS,DEPT ASTRON,URBANA,IL 61801. RP ZIURYS, LM (reprint author), ARIZONA STATE UNIV,DEPT CHEM,TEMPE,AZ 85287, USA. NR 27 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1994 VL 430 IS 2 BP 706 EP 712 DI 10.1086/174442 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ043 UT WOS:A1994NZ04300023 ER PT J AU JARRETT, TH NOVAK, G XIE, T GOLDSMITH, PF AF JARRETT, TH NOVAK, G XIE, T GOLDSMITH, PF TI MAGNETIC-FIELD STRUCTURE IN MONOCEROS R2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (MONOCEROS R2); ISM, MAGNETIC FIELDS; POLARIZATION ID STAR-FORMING REGIONS; INFRARED POLARIMETRY; MOLECULAR CLOUDS; INTERSTELLAR POLARIZATION; SELECTIVE EXTINCTION; COMPLEXES; ORION; RADIATION; VICINITY; OBJECTS AB We have carried out polarimetric observations to investigate the geometry of the magnetic field in the giant molecular cloud Monoceros R2. This study is based upon deep R-band CCD polarimetry, covering a total area of 0.5 deg2 of the giant molecular cloud. The data were calibrated using a new technique that relies on obtaining broad-band photometry of stars simultaneously with polarimetric photometry of the Mon R2 fields, thus providing an accurate means of measuring the electric vectors of starlight which is polarized by the foreground dust grains aligned by the magnetic field in the Mon R2 GMC. In this work, (1) we were able to continuously trace magnetic field lines from the largest scales in Mon R2 to the detailed structure of the field in the dense core, as determined from infrared polarimetry; and (2) we have found that the ambient field is apparently modified by a large-scale structure in the Mon R2 cloud. The mean angle of polarization for the complete sample we measured is 158-degrees, which is roughly coincident with the local Galactic magnetic field (155-degrees). The dispersion in the angle of polarization is 33-degrees, similar to that found in the Orion GMC. The dispersion in angle of polarization for stars located along the western side of the three CCD fields is 22-degrees. The CCD fields are bisected by a dense ridge of gas defining the boundary of an expanding gas shell that recent observational results at millimeter wavelengths now reveal dominates the Mon R2 GMC. Our results suggest that the expanding shell has distorted the magnetic field lines extending from the core to the northern gas structure comprising Mon R2. C1 CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. NORTHWESTERN UNIV,DEPT PHYS & ASTRON,EVANSTON,IL 60208. JET PROP LAB,PASADENA,CA 91109. CORNELL UNIV,DEPT ASTRON,NATL ASTRON & IONOSPHERE CTR,ITHACA,NY 14853. RI Goldsmith, Paul/H-3159-2016 NR 58 TC 17 Z9 17 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1994 VL 430 IS 2 BP 743 EP 756 DI 10.1086/174445 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ043 UT WOS:A1994NZ04300026 ER PT J AU RHO, JH PETRE, R SCHLEGEL, EM HESTER, JJ AF RHO, JH PETRE, R SCHLEGEL, EM HESTER, JJ TI AN X-RAY AND OPTICAL STUDY OF THE SUPERNOVA REMNANT W44 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (W44); SHOCK WAVES; SUPERNOVA REMNANTS; X-RAYS, ISM ID INTERSTELLAR-MEDIUM; NOVA REMNANTS; CYGNUS LOOP; EMISSION; EVOLUTION; CLOUDS; SPECTRUM; BUBBLES; SHELL; RADIO AB We report the results of a 8000 s observation of the supernova remnant W44 using the ROSAT PSPC. The image shows the same centrally peaked morphology observed by the Einstein IPC and contrasts with the shell-like radio morphology. The eastern limb shows a lack of X-ray emission within the radio shell, probably due to the interaction between the SNR and a molecular cloud. No counterpart to the pulsar 1853+01 in W44 has been detected, with L(X) < 1.3 x 10(32) ergs s-1 in the 0.2-2.4 keV band. The spectral analysis of the central part of W44, combining EXOSAT ME and Einstein SSS data, shows that the shocked plasma has not reached ionization equilibrium. The best nonequilibrium fit to PSPC, ME, and SSS spectra gives eta = 10(51) ergs cm-6, T(s) = 10(7) K with T(e) = T(i), suggesting conditions are approaching ionization equilibrium. There is no evidence of enhanced abundances of Mg, Si, S, or Fe. The variation of temperature and column density was obtained region by region using the PSPC and Einstein IPC. The temperature is largely uniform over the remnant, but strong column density variations are found to be consistent with molecular clouds in the line of sight. An evaporation model with a two-phase interstellar medium structure of clumps and interclump gas (White & Long 1991) can explain the X-ray centrally peaked morphology of W44. The clumps remaining behind a SN shock provide a reservoir of material, and evaporate to increase the density of X-ray emitting gas in the interior of a SNR. The uniform temperature distribution of W44 strongly supports the predictions of this model. In addition, mosaiced Halpha and [S II] images of W44, taken using the PFUEI camera on the Palomar 60'' telescope, reveal the first discovery of optical filaments (both Halpha and (S II]) in the northwestern and southeastern portion of the remnant, within the X-ray emitting region. The optical filaments and the X-ray image showing locally brighter emission and clumps along the filaments suggest both are produced by the interaction between the supernova shock front and regions of enhanced ambient density. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. NR 56 TC 80 Z9 80 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1994 VL 430 IS 2 BP 757 EP & DI 10.1086/174446 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ043 UT WOS:A1994NZ04300027 ER PT J AU WINGET, DE NATHER, RE CLEMENS, JC PROVENCAL, JL KLEINMAN, SJ BRADLEY, PA CLAVER, CF DIXSON, JS MONTGOMERY, MH HANSEN, CJ HINE, BP BIRCH, P CANDY, M MARAR, TMK SEETHA, S ASHOKA, BN LEIBOWITZ, EM ODONOGHUE, D WARNER, B BUCKLEY, DAH TRIPE, P VAUCLAIR, G DOLEZ, N CHEVRETON, M SERRE, T GARRIDO, R KEPLER, SO KANAAN, A AUGUSTEIJN, T WOOD, MA BERGERON, P GRAUER, AD AF WINGET, DE NATHER, RE CLEMENS, JC PROVENCAL, JL KLEINMAN, SJ BRADLEY, PA CLAVER, CF DIXSON, JS MONTGOMERY, MH HANSEN, CJ HINE, BP BIRCH, P CANDY, M MARAR, TMK SEETHA, S ASHOKA, BN LEIBOWITZ, EM ODONOGHUE, D WARNER, B BUCKLEY, DAH TRIPE, P VAUCLAIR, G DOLEZ, N CHEVRETON, M SERRE, T GARRIDO, R KEPLER, SO KANAAN, A AUGUSTEIJN, T WOOD, MA BERGERON, P GRAUER, AD TI WHOLE EARTH TELESCOPE OBSERVATIONS OF THE DBV WHITE-DWARF GD-358 SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, INDIVIDUAL (GD-358); STARS, OSCILLATIONS; WHITE DWARFS ID ZZ-CETI STARS; ASTEROSEISMOLOGY AB We report on the analysis of 154 hours of early continuous high-speed photometry on the pulsating DB white dwarf (DBV) GD 358, obtained during the Whole Earth Telescope (WET) run of 1990 May. The power spectrum of the light curve is dominated by power in the range from 1000 to 2400 muHz, with more than 180 significant peaks in the total spectrum. We identify all of the triplet frequencies as degree l = 1, and from the details of their spacings we derive the total stellar mass as 0.61 +/- 0.03 M., the mass of the outer helium envelope as 2.0 +/- 1.0 x 10(-6) M*, the absolute luminosity as 0.050 +/- 0.012 L. and the distance as 42 +/- 3 pc. We find strong evidence for differential rotation in the radial direction-the outer envelope is rotating at least 1.8 times faster than the core-and we detect the presence of a weak magnetic field with a strength of 1300 +/- 300 G. We also find a significant power at the sums and differences of the dominant frequencies, indicating nonlinear processes are significant, but they have a richness and complexity that rules out resonant mode coupling as a major cause. C1 UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. UNIV COLORADO,BOULDER,CO 80309. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. PERTH OBSERV,BICKLEY,WA,AUSTRALIA. INDIAN SPACE RES ORG,ISRO SATELLITE CTR,DIV TECH PHYS,BANGALORE 560017,INDIA. TEL AVIV UNIV,DEPT PHYS & ASTRON,IL-69978 TEL AVIV,ISRAEL. UNIV CAPE TOWN,DEPT ASTRON,RONDEBOSCH 7700,SOUTH AFRICA. OBSERV MIDI PYRENEES,F-31400 TOULOUSE,FRANCE. OBSERV PARIS,F-9195 MEUDON,FRANCE. INST ASTROFIS ANDALUCIA,GRANADA,SPAIN. UNIV FED RIO GRANDE SUL,INST FIS,BR-90049 PORTO ALEGRE,RS,BRAZIL. EUROPEAN SO OBSERV,LA SILLA,CHILE. FLORIDA INST TECHNOL,DEPT PHYS & SPACE SCI,MELBOURNE,FL 32901. UNIV MONTREAL,DEPT PHYS,MONTREAL H3C 3J7,QUEBEC,CANADA. UNIV ARKANSAS,DEPT PHYS & ASTRON,LITTLE ROCK,AR 72204. RP WINGET, DE (reprint author), UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712, USA. RI Kepler, S. O. /H-5901-2012 OI Kepler, S. O. /0000-0002-7470-5703 NR 26 TC 181 Z9 181 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 AUG 1 PY 1994 VL 430 IS 2 BP 839 EP 849 DI 10.1086/174455 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ043 UT WOS:A1994NZ04300036 ER PT J AU MOSES, D COOK, JW BARTOE, JDF BRUECKNER, GE DERE, KP WEBB, DF DAVIS, JM HARVEY, JW RECELY, F MARTIN, SF ZIRIN, H AF MOSES, D COOK, JW BARTOE, JDF BRUECKNER, GE DERE, KP WEBB, DF DAVIS, JM HARVEY, JW RECELY, F MARTIN, SF ZIRIN, H TI SOLAR FINE-SCALE STRUCTURES IN THE CORONA, TRANSITION REGION, AND LOWER ATMOSPHERE SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, CORONA; SUN, MAGNETIC FIELDS; SUN, TRANSITION REGION; SUN, X-RAYS, GAMMA-RAYS ID RAY BRIGHT POINTS; TEMPERATURE-MINIMUM REGION; X-RAY; QUIET SUN; EXPLOSIVE EVENTS; MAGNETIC NETWORK; CHROMOSPHERE; IDENTIFICATION; TELESCOPE; MODELS AB The American Science and Engineering Soft X-ray Imaging Payload and the Naval Research Laboratory High Resolution Telescope and Spectrograph (HRTS) were launched from White Sands on 1987 December 11 in coordinated sounding rocket flights. The goal was to investigate the correspondence of fine-scale structures from different temperature regimes in the solar atmosphere, and particularly the relationship between X-ray bright points (XBPs) and transition region explosive events. We present results of the analysis of co-aligned X-ray images, maps of sites of transition region explosive events observed in C IV (10(5) K), HRTS 1600 angstrom spectroheliograms of the T(min) region, and ground-based magnetogram and He I 10830 angstrom images. We examined the relationship of He I 10830 angstrom dark features and evolving magnetic features which correspond to XBPs. We note a frequent double ribbon pattern of the He i dark feature counterparts to XBPs. We discuss an analysis of the relationship of XBPs to evolving magnetic features by Webb et al., which shows that converging magnetic features of opposite polarity are the most significant magnetic field counterparts to XBPs. The magnetic bipolar features associated with XBPs appear as prominent network elements in chromospheric and transition region images. The features in C IV observations corresponding to XBP sites are in general bright, larger scale (approximately 10 arcsec) regions of complex velocity fields of order 40 km s-1, which is typical of brighter C IV network elements. These C IV features do not reach the approximately 100 km s-1 velocities seen in the C IV explosive events. Also, there are many similar C IV bright network features without a corresponding XBP in the X-ray image. The transition region explosive events do not correspond directly to XBPs. The explosive events appear to be concentrated in the quiet Sun at the edges of strong network, or within weaker field strength network regions. We find a greater number of C IV events than expected from the results of a previous Spacelab 2 HRTS disk survey. We attribute this at least partly to better spatial resolution with the newer HRTS data. The full-disk X-ray image shows a pattern of dark lanes in quiet Sun areas. The number density of C IV events is twice as large inside as outside a dark lane (4.6 x 10(-3) vs. 2.3 x 10(-3) explosive events per arcsec2). The dark lane corresponds to an old decaying magnetic neutral line. We suggest that this provides an increased opportunity for small-scale convergence and reconnection of opposite polarity magnetic field features, in analogy with the results of Webb et al. for XBPs but at a reduced scale of reconnection. C1 NASA, WASHINGTON, DC 20546 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. BOSTON COLL, INST SPACE RES, NEWTON, MA 02159 USA. NATL OPT ASTRON OBSERV, NATL SOLAR OBSERV, TUCSON, AZ 85726 USA. NOAA, SPACE ENVIRONM LAB, BOULDER, CO 80303 USA. CALTECH, DIV PHYS MATH & ASTRON 26433, PASADENA, CA 91125 USA. CALTECH, BIG BEAR SOLAR OBSERV, PASADENA, CA 91125 USA. RP USN, RES LAB, EO HULBURT CTR SPACE RES, CODE 7660, WASHINGTON, DC 20375 USA. NR 54 TC 29 Z9 30 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 AUG 1 PY 1994 VL 430 IS 2 BP 913 EP + DI 10.1086/174461 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ043 UT WOS:A1994NZ04300042 ER PT J AU CORNETT, RH HILL, JK BOHLIN, RC OCONNELL, RW ROBERTS, MS SMITH, AM STRECHER, TP AF CORNETT, RH HILL, JK BOHLIN, RC OCONNELL, RW ROBERTS, MS SMITH, AM STRECHER, TP TI UIT - ULTRAVIOLET OBSERVATIONS OF THE SMALL MAGELLANIC CLOUD SO ASTROPHYSICAL JOURNAL LA English DT Article DE EXTINCTION; GALAXIES, INDIVIDUAL (MAGELLANIC CLOUDS); GALAXIES, LUMINOSITY FUNCTION, MASS FUNCTION; ULTRAVIOLET, GENERAL ID INTERSTELLAR EXTINCTION; ASSOCIATIONS; TELESCOPE; STARS AB UIT far-ultraviolet (FUV) and near-ultraviolet (NUV) images are presented for a 40' field at the southwest end of the SMC centered near the Halpha emission object Henize 19. Photometry is obtained for 1309 stars common to the FUV (lambda(eff) = 1620 angstrom) and NUV (lambda(eff) = 2490 angstrom) images. We use UIT photometry and imagery to derive a UV color-magnitude diagram for hot field stars; confirm the consistency of low-metal-abundance stellar evolutionary models with the observations; study dust distribution in the field, finding an increase in E(B - V) from the northeast to the southwest; confirm for a large number of stars an extinction curve, like that derived by Hutchings for the SMC, which rises steeply from NUV to FUV; and derive a mass function for SMC field stars and its lack of dependence on assumed extinction curve characteristics. The mass function has a slope within the accepted range (GAMMA = -1.7 +/- 0.5) over a wide range of assumed extinction parameters, including variations of the size (+/- approximately 1.5 mag x E(B - V) in the FUV) seen in the Galaxy. C1 NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP CORNETT, RH (reprint author), HUGHES STX CORP,GODDARD SPACE FLIGHT CTR,CODE 681,GREENBELT,MD 20771, USA. NR 22 TC 7 Z9 7 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1994 VL 430 IS 2 BP L117 EP & DI 10.1086/187452 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ045 UT WOS:A1994NZ04500009 ER PT J AU GORSKI, KM AF GORSKI, KM TI ON DETERMINING THE SPECTRUM OF PRIMORDIAL INHOMOGENEITY FROM THE COBE1 DMR SKY MAPS - METHOD SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; METHODS, ANALYTICAL ID DIFFERENTIAL MICROWAVE RADIOMETER; COSMIC BACKGROUND-RADIATION; FLUCTUATIONS AB The natural approach to a spectral analysis of data distributed on the sky employs spherical harmonic decomposition. A common problem encountered in practical astronomy is the lack of full sky coverage in the available data. For example, the removal of the Galactic plane data from the COBE DMR sky maps compromises Fourier analysis of the cosmic microwave background (CMB) temperature distribution due to the loss of orthogonality of the spherical harmonics. An explicit method for constructing orthonormal functions on an incomplete (e.g., Galaxy-cut) sphere is presented. These functions should be used in the proper Fourier analysis of the COBE DMR sky maps to provide the correct input for the determination of the spectrum of primordial inhomogeneity. The results of such an analysis are presented in an accompanying Letter. A similar algebraic construction of appropriate functions can be devised for other astronomical applications. RP GORSKI, KM (reprint author), UNIV SPACE ASSOC,NASA,GOODARD SPACE FLIGHT CTR,CODE 685 5,GREENBELT,MD 20771, USA. NR 15 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 AUG 1 PY 1994 VL 430 IS 2 BP L85 EP L88 DI 10.1086/187444 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ045 UT WOS:A1994NZ04500001 ER PT J AU GORSKI, KM HINSHAW, G BANDAY, AJ BENNETT, CL WRIGHT, EL KOGUT, A SMOOT, GF LUBIN, P AF GORSKI, KM HINSHAW, G BANDAY, AJ BENNETT, CL WRIGHT, EL KOGUT, A SMOOT, GF LUBIN, P TI ON DETERMINING THE SPECTRUM OF PRIMORDIAL INHOMOGENEITY FROM THE COBE DMR SKY MAPS - RESULTS OF 2-YEAR DATA-ANALYSIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS ID DIFFERENTIAL MICROWAVE RADIOMETER AB A new technique of Fourier analysis on a cut sky has been applied to the two-year COBE DMR 53 and 90 GHz sky maps. The Bayesian power spectrum estimation results are consistent with the Harrison-Zel'dovich n = 1 model. The maximum likelihood estimates of the usual parameters defining the power spectrum of primordial perturbations are n = 1.22 (1.02) and Q(rms-PS) = 17 (20) muK including (excluding) the quadrupole. A spectral-index-independent normalization is naturally expressed for the two-year maps in terms of the multipole amplitude a9 = 8.2 (8.3) muK (to approximately 12 sigma significance). The marginal likelihood function on n obtained by integration with respect to a9 renders n = 1.17 +/- 0.31 (0.96 +/- 0.36). RP GORSKI, KM (reprint author), UNIV SPACE RES ASSOC,NASA,GOODARD SPACE FLIGHT CTR,CODE 685 3,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 12 TC 154 Z9 154 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD AUG 1 PY 1994 VL 430 IS 2 BP L89 EP L92 DI 10.1086/187445 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ045 UT WOS:A1994NZ04500002 ER PT J AU MITCHELL, KJ DENNISON, B CONDON, JJ ALTSCHULER, DR PAYNE, HE ODELL, SL BRODERICK, JJ AF MITCHELL, KJ DENNISON, B CONDON, JJ ALTSCHULER, DR PAYNE, HE ODELL, SL BRODERICK, JJ TI RESULTS OF A 5-YEAR PROGRAM OF MULTIFREQUENCY MONITORING OF LOW-FREQUENCY VARIABLE RADIO-SOURCES SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ISM, GENERAL; QUASARS, GENERAL; RADIO CONTINUUM, GALAXIES ID VARIABILITY AB We present the results of a detailed multifrequency monitoring program of low-frequency variable radio sources. This consists of light curves at 318, 430, 606, 880, and 1400 MHz over a 5 year period. The observations were carried out with the Arecibo 305 m radiotelescope and the Green Bank 91 m radio telescope. The spectral characteristics of the variations confirm the general picture that at least two mechanisms are responsible. The first is clearly intrinsic evolution of synchrotron-emitting components as it is manifested by variations that appear first and most strongly at high frequencies, subsequently drifting to lower frequencies with diminished amplitude. The more common type of low-frequency variability, however, dominates at frequencies below approximately 800 MHz, while the variations near 1 GHz are often quite weak. This spectral property is strong evidence that these variations are interstellar refractive scintillation. C1 VIRGINIA POLYTECH INST & STATE UNIV,CTR STOCHAST PROC SCI & ENGN,BLACKSBURG,VA 24061. NATL RADIO ASTRON OBSERV,CHARLOTTESVILLE,VA 22903. NATL ASTRON & IONOSPHERE CTR,ARECIBO,PR 00612. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. VIRGINIA POLYTECH INST & STATE UNIV,DEPT PHYS,BLACKSBURG,VA 24061. UNIV PUERTO RICO,FAC NAT SCI,DEPT PHYS,RIO PIEDRAS,PR 00931. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP MITCHELL, KJ (reprint author), GEN SCI CORP,6100 CHEVY CHASE DR,LAUREL,MD 20707, USA. OI O'Dell, Stephen/0000-0002-1868-8056 NR 18 TC 25 Z9 25 U1 0 U2 2 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD AUG PY 1994 VL 93 IS 2 BP 441 EP 453 DI 10.1086/192061 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX063 UT WOS:A1994NX06300003 ER PT J AU HYUNG, S ALLER, LH FEIBELMAN, WA AF HYUNG, S ALLER, LH FEIBELMAN, WA TI THE SPECTRUM OF THE VARIABLE PLANETARY-NEBULA IC-4997 SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ISM, ABUNDANCES; ISM, STRUCTURE; PLANETARY NEBULAE, INDIVIDUAL (IC-4997) ID EMISSION-LINES; IUE OBSERVATIONS; GASEOUS NEBULAE; CENTRAL STARS; ORION NEBULA; INTENSITIES; ATMOSPHERES; VARIABILITY; EVOLUTION; NGC-6572 AB The compact, dusty, presumably young planetary nebula (PN) IC 4997 has been studied extensively since the variability of the lambda4363/lambda4340 ratio was established in 1956. Since 1938, other nebular lines have shown changes. IC 4997 is also unique because of the great density range revealed by its spectrum which goes in excitation from Mg I to [Ar IV]. We present a detailed listing of spectral lines from 360 to 1005 nm. The diagnostic diagram shows that the spectrum can be interpreted only in terms of strata with a huge density gamut. Essential spectral features can be reproduced approximately by a model consisting of a geometrically thin shell of density around 10(7) atoms cm-3, surrounded by a much larger shell with a density of about 10(4) atoms cm-3. The actual, certainly more complex structure can be evaluated only when high resolution spatial imaging is at hand. The usual method of getting abundances from N(ion)/N(H+) and ionization correction factors (ICFs) cannot be applied here. It is argued that a reasonable theoretical model that represents the spectrum provides a valid initial approximation to nebular abundances. We propose that the chemical composition of IC 4997 does not differ greatly from that of the Sun. The finally adopted model suggests that the ejection of the material destined to form the inner shell occurred between 1900 and 1960, but observational evidence of such an ejection event is lacking. Perhaps the shell was accelerated. A need for further study is emphasized, especially the role of dust which appears to contribute 2% of the total mass. More attention to this object is recommended. An accurate measurement of its distance is especially desirable. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HYUNG, S (reprint author), UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024, USA. NR 63 TC 52 Z9 52 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD AUG PY 1994 VL 93 IS 2 BP 465 EP 483 DI 10.1086/192063 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX063 UT WOS:A1994NX06300005 ER PT J AU KAITCHUCK, RH SCHLEGEL, EM HONEYCUTT, RK HORNE, K MARSH, TR WHITE, JC MANSPERGER, CS AF KAITCHUCK, RH SCHLEGEL, EM HONEYCUTT, RK HORNE, K MARSH, TR WHITE, JC MANSPERGER, CS TI AN ATLAS OF DOPPLER EMISSION-LINE TOMOGRAPHY OF CATACLYSMIC VARIABLE-STARS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ACCRETION, ACCRETION DISKS; ATLASES; BINARIES, CLOSE; LINE PROFILES; NOVAE, CATACLYSMIC VARIABLES ID TIME-RESOLVED SPECTROPHOTOMETRY; NOVA IP-PEGASI; ACCRETION DISKS; SPECTROSCOPIC OBSERVATIONS; MASS DETERMINATION; URSAE MAJORIS; AC-CANCRI; EX HYDRAE; OLD NOVA; X-RAY AB Doppler emission-line tomography is a technique similar to medical tomography. In this atlas the emission-line profiles of cataclysmic variable stars, seen at different orbital phases, are transformed into velocity space images. This transformation makes many of the complex line profile changes easier to interpret. The emission contributions of the disk and the s-wave are clearly separated in these images, and any emission from the stream and the secondary star can often be identified. In this atlas, Doppler tomograms of Hbeta, He I lambda4471, and He II lambda4686 emission lines of 18 cataclysmic variable stars are presented. The Doppler images provide insights into the individual systems and a better technique for measuring the radial velocity amplitude of the white dwarf. C1 NASA,GODDARD SPACE FLIGHT CTR,USRA,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. INDIANA UNIV,DEPT ASTRON,BLOOMINGTON,IN 47405. FOD,ATSC,GODDARD CORP PK,CANHAM,MD 20706. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV OXFORD,DEPT ASTROPHYS,NUCL PHYS LAB,OXFORD OX1 3RM,ENGLAND. KITT PEAK NATL OBSERV,TUCSON,AZ 85726. UNIV UTRECHT,INST STERREKUNDIG,3508 TA UTRECHT,NETHERLANDS. MIDDLE TENNESSEE STATE UNIV,DEPT CHEM & PHYS,MURFREESBORO,TN 37132. RP KAITCHUCK, RH (reprint author), BALL STATE UNIV,DEPT PHYS & ASTRON,MUNCIE,IN 47306, USA. NR 57 TC 74 Z9 74 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD AUG PY 1994 VL 93 IS 2 BP 519 EP & DI 10.1086/192065 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX063 UT WOS:A1994NX06300007 ER PT J AU LANGE, RD GIBSON, LA DRISCOLL, TB ALLEBBAN, Z ICHIKI, AT AF LANGE, RD GIBSON, LA DRISCOLL, TB ALLEBBAN, Z ICHIKI, AT TI EFFECTS OF MICROGRAVITY AND INCREASED GRAVITY ON BONE-MARROW OF RATS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID SPACE AB Astronauts have a reduction in their red cell mass when exposed to microgravity. This is probably mainly due to a physiological response to decreased energy requirements. Further studies of erythropoiesis were carried out in microgravity on rats flown on Soviet Biosatellite 2044 and in hypergravity by centrifugation at 2G. Studies included: bone marrow cell differential counts, clonal studies of RBC colony formation, and plasma erythropoietin determinations. In the bone marrow of Cosmos flight animals there was a slight increase in granulocytic cells and in centrifuged animals, a slight decrease in the percentage of erythroid cells which led to an increased M:E ratio. The bone marrow cells of flight and centrifuged rats responded to erythropoietin. Cosmos flight animals' cells formed fewer CFU-E than the controls but this was reversed in the centrifuge studies. There were no essential differences in the erythropoietin levels of test groups as compared to control groups. C1 BAYLOR COLL MED,HOUSTON,TX 77030. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. RP LANGE, RD (reprint author), UNIV TENNESSEE,MED CTR,DEPT MED BIOL,1924 ALCOA HIGHWAY,KNOXVILLE,TN 37996, USA. NR 22 TC 4 Z9 4 U1 0 U2 1 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 AUG PY 1994 VL 65 IS 8 BP 730 EP 735 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA PA921 UT WOS:A1994PA92100006 PM 7980333 ER PT J AU PARNAS, BR AF PARNAS, BR TI ANALYSIS OF THE RESPONSE PROPERTIES OF A COMPUTATIONALLY EFFICIENT SPIKE INITIATOR MODEL SO BIOLOGICAL CYBERNETICS LA English DT Article ID COCHLEAR NUCLEUS; CELLS AB A simple model for neuronal spike initiation is presented. It comprises two linear differential equations and is based on the work of Hill, Rashevsky and Monnier (Rashevsky 1933; Monnier 1934; Hill 1936). Three different versions of the model and the corresponding assumptions are described. The intrinsic noise model used with the deterministic equations is described. The equations are analyzed through the direct solution of relevant equations and the technique of phase plane analysis. The analysis reveals that a subset of the model parameters is responsible for the distinction between spike initiator models which fire a single spike and those that fire repetitively in the presence of a sustained stimulus. Relationships between stimulus intensity and different modes of operation are derived. The effects of the three different versions of the model are compared analytically. C1 UNIV CALIF BERKELEY,DEPT EECS,BERKELEY,CA 94720. RP PARNAS, BR (reprint author), NASA,AMES RES CTR,CTR BIOCOMPUTAT,MS 239-11,MOFFETT FIELD,CA 94035, USA. NR 21 TC 2 Z9 2 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0340-1200 J9 BIOL CYBERN JI Biol. Cybern. PD AUG PY 1994 VL 71 IS 4 BP 319 EP 332 DI 10.1007/BF00239619 PG 14 WC Computer Science, Cybernetics; Neurosciences SC Computer Science; Neurosciences & Neurology GA PE407 UT WOS:A1994PE40700004 PM 7948223 ER PT J AU COLEMAN, GN FERZIGER, JH SPALART, PR AF COLEMAN, GN FERZIGER, JH SPALART, PR TI A NUMERICAL STUDY OF THE CONVECTIVE BOUNDARY-LAYER SO BOUNDARY-LAYER METEOROLOGY LA English DT Article ID COLD-AIR OUTBREAK; HORIZONTAL ROLL VORTICES; LARGE-EDDY SIMULATIONS; TURBULENT EKMAN LAYER; LABORATORY MODEL; VELOCITY AB Computations of the buoyantly unstable Ekman layer are performed at low Reynolds number. The turbulent fields are obtained directly by solving the three-dimensional time-dependent Navier-Stokes equations (using the Boussinesq approximation to account for buoyancy effects), and no turbulence model is needed. Two levels of heating are considered, one quite vigorous, the other more moderate. Statistics for the vigorously heated case are found to agree reasonably well with laboratory, field, and large-eddy simulation results, when Deardorff's mixed-layer scaling is used. No indication of large-scale longitudinal roll cells is found in this convection-dominated flow, for which the inversion height to Obukhov length scale ratio -Z(i)/L* =26. However, when heating is more moderate (so that -Z(i)/L* = 2), evidence of coherent rolls is present. About 10% of the total turbulent kinetic energy and turbulent heat flux, and 20% of the Reynolds shear stress, are estimated to be a direct consequence of the observed cells. C1 STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 42 TC 23 Z9 23 U1 1 U2 3 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0006-8314 J9 BOUND-LAY METEOROL JI Bound.-Layer Meteor. PD AUG PY 1994 VL 70 IS 3 BP 247 EP 272 DI 10.1007/BF00709121 PG 26 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PE939 UT WOS:A1994PE93900002 ER PT J AU STABENAU, EK HEMING, TA AF STABENAU, EK HEMING, TA TI THE IN-VITRO RESPIRATORY AND ACID-BASE PROPERTIES OF BLOOD AND TISSUE FROM THE KEMPS RIDLEY SEA-TURTLE, LEPIDOCHELYS-KEMPI SO CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE LA English DT Article ID OXYGEN-TRANSPORT; GAS-EXCHANGE; TEMPERATURE; MUSCLE; LUNGS; COLD; PH AB We determined the in vitro respiratory and acid-base properties of blood and tissue from Kemp's ridley sea turtles (Lepidochelys kempi). Blood O-2 dissociation curves of ridley turtles were sigmoid, with a P-50 of 31.2 +/- 0.3 (mean +/- SD) torr. at 25 degrees C and pH 7.51. Increments in temperature or PCO2 were associated with a shift of the O-2 dissociation curves to the right and, hence, a reduction in hemoglobin-O-2 binding affinity. The apparent heat of oxygenation, which is a measure of the temperature sensitivity of hemoglobin-O-2 affinity, was -10.5 kcal/mol O-2. The degree of cooperativity of O-2 for hemoglobin binding sites, as measured by the Hill coefficient, increased at higher temperatures (20-30 degrees C at a PCO2 of 37 torr), but was unaffected by changes in PCO2 (37-52 ton at 25 degrees C). The CO2-Bohr effect was -0.34 torr/pH unit. The CO2 capacitance coefficient of whole blood and plasma declined as a function of increased PCO2 (22 degrees C). Non-bicarbonate buffer capacities (22 degrees C) were 19.7, 18.5, and 6.4 slykes for whole blood, true plasma, and separated plasma, respectively. The skeletal muscle myoglobin content was 3.1 +/- 0.84 mg.g(-1) of tissue. The respiratory and acid-base properties of blood and tissue from Kemp's ridley sea turtles are consistent with those of species that utilize lung O-2 stores during long-term aerobic dives. The enhanced hemoglobin-O-2 temperature sensitivity exhibited by the ridley turtle could be a physiological adaptation for life in coastal environments that typically undergo substantial fluctuations in temperature. C1 NATL MARINE FISHERIES SERV,GALVESTON,TX 77551. UNIV TEXAS,DEPT PHYSIOL & BIOPHYS,GALVESTON,TX 77550. UNIV TEXAS,DEPT INTERNAL MED,GALVESTON,TX 77550. NR 31 TC 7 Z9 7 U1 0 U2 0 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 AUG PY 1994 VL 72 IS 8 BP 1403 EP 1408 DI 10.1139/z94-185 PG 6 WC Zoology SC Zoology GA PV940 UT WOS:A1994PV94000006 ER PT J AU DECOLSTOUN, FB KHITROVA, G FEDOROV, AV NELSON, TR LOWRY, C BRENNAN, TM HAMMONS, BG MAKER, PD AF DECOLSTOUN, FB KHITROVA, G FEDOROV, AV NELSON, TR LOWRY, C BRENNAN, TM HAMMONS, BG MAKER, PD TI TRANSVERSE-MODES, VORTICES AND VERTICAL-CAVITY SURFACE-EMITTING LASERS SO CHAOS SOLITONS & FRACTALS LA English DT Article ID OPTICAL VORTEX SOLITONS; SPATIOTEMPORAL STRUCTURES; PHASE SINGULARITIES; PATTERNS; POLARIZATION; STABILITY; CO2-LASER; EMISSION; BEAMS AB Injection locking dramatically modifies the phase and transverse output intensity profile of vertical-cavity surface-emitting lasers (VCSELs). Injection can induce a VCSEL to emit a high-order transverse mode. Vortices are generated by three different methods: insertion of a helicoidal phase mask, interference of two Gaussian beams, and injection locking of the TEM(01) and TEM(01) modes of a VCSEL to form the TEM*(01) donut mode. The first two methods stem from geometrical optics; the third method involves nonlinear mode competition in the laser cavity. C1 SANDIA NATL LABS,DEPT 1311,ALBUQUERQUE,NM 87185. CALTECH,JET PROP LAB,PASADENA,CA 91109. SI VAVILOV STATE OPT INST,ST PETERSBURG 199034,RUSSIA. DIRNSA,FORT GG MEADE,MD 20755. RP DECOLSTOUN, FB (reprint author), UNIV ARIZONA,CTR OPT SCI,TUCSON,AZ 85721, USA. NR 39 TC 40 Z9 40 U1 0 U2 4 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0960-0779 J9 CHAOS SOLITON FRACT JI Chaos Solitons Fractals PD AUG-SEP PY 1994 VL 4 IS 8-9 BP 1575 EP 1596 DI 10.1016/0960-0779(94)90098-1 PG 22 WC Mathematics, Interdisciplinary Applications; Physics, Multidisciplinary; Physics, Mathematical SC Mathematics; Physics GA PV522 UT WOS:A1994PV52200019 ER PT J AU MARDER, SR PERRY, JW YAKYMYSHYN, CP AF MARDER, SR PERRY, JW YAKYMYSHYN, CP TI ORGANIC SALTS WITH LARGE 2ND-ORDER OPTICAL NONLINEARITIES SO CHEMISTRY OF MATERIALS LA English DT Review ID 2ND-HARMONIC GENERATION; DIPOLE-MOMENT; POLARIZABILITIES; DERIVATIVES; CRYSTALS; HYPERPOLARIZABILITIES; NITROANILINES; MULTILAYERS; MOLECULES; SYSTEMS AB This paper presents a review of recent work on the development of organic salts for second-order nonlinear optical applications. In particular, salts in which the cation has been designed to have a large molecular hyperpolarizability and in which variation of the counterion facilitates preparation of crystals with the required noncentrosymmetric packing are discussed. In many cases, this approach has led to materials with large powder second harmonic generation (SHG) efficiencies. One salt, NN-dimethylamino-N'-methylstilbazolium p-toluenesulfonate, DAST, exhibited an SHG efficiency > 1000 times that of a urea powder reference. A common layered-polar-sheet crystal packing motif was observed for DAST and several salt crystals that have been examined- crystallographically. A possible explanation for the high incidence of noncentrosymmetric packing in these structures is discussed. Finally, the growth and properties of DAST single crystals are reviewed. C1 CALTECH, BECKMAN INST, CTR MOLEC MAT RESOURCE, PASADENA, CA 91125 USA. ASEA BROWN BOVERIE TRANSMISS TECHNOL INST, RALEIGH, NC 27606 USA. RP MARDER, SR (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 79 TC 346 Z9 348 U1 2 U2 54 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0897-4756 EI 1520-5002 J9 CHEM MATER JI Chem. Mat. PD AUG PY 1994 VL 6 IS 8 BP 1137 EP 1147 DI 10.1021/cm00044a012 PG 11 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA PC721 UT WOS:A1994PC72100012 ER PT J AU ESPOSITO, G MIELE, G ROSA, L AF ESPOSITO, G MIELE, G ROSA, L TI ONE-LOOP EFFECTIVE POTENTIAL FOR SO(10) GUT THEORIES IN DESITTER SPACE SO CLASSICAL AND QUANTUM GRAVITY LA English DT Article ID LEFT-RIGHT SYMMETRY; DE-SITTER SPACE; UNIFICATION; UNIVERSE; BREAKING; BROKEN; MODELS AB Zeta-function regularization is applied to the evaluation of the one-loop effective potential for SO(10) grand unified theories in de Sitter cosmologies. When the Higgs scalar field belongs to the 210-dimensional irreducible representation of SO(10), attention is focused on the mass matrix relevant for the SU(3) X SU(2) X U(1) symmetry-breaking direction, to agree with the low-energy phenomenology of the standard model of particle physics. The analysis is restricted to those values of the tree-level potential parameters for which the absolute minimum of the classical potential has been evaluated. As shown in the recent literature, such minima turn out to be SO(6) X SO(4) or SU(3) X SU(2) X U(1) invariant. Electroweak phenomenology is more naturally derived, however, from the former minima. Hence the values of the parameters leading to the alternative set of minima have been discarded. Within this framework, the flat-space limit and the general form of the one-loop effective potential are studied in detail by using analytic and numerical methods. It turns out that, as far as the absolute-minimum direction is concerned, the flat-space limit of the one-loop calculation with a de Sitter background does not change the results previously obtained in the literature, where the tree-level potential in flat spacetime was studied. Moreover, even when curvature effects are no longer negligible in the one-loop potential, it is found that the early universe can only reach the SO(6) X SO(4) absolute minimum. C1 DIPARTIMENTO SCI FIS,I-80125 NAPLES,ITALY. FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP ESPOSITO, G (reprint author), IST NAZL FIS NUCL,MOSTRA OLTREMARE PADIGL 20,I-80125 NAPLES,ITALY. RI Miele, Gennaro/F-3628-2010; Rosa, Luigi/K-3869-2015; Esposito, Giampiero/H-3405-2012 OI Miele, Gennaro/0000-0002-2028-0578; Rosa, Luigi/0000-0002-5595-5037; Esposito, Giampiero/0000-0001-5930-8366 NR 18 TC 9 Z9 9 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0264-9381 J9 CLASSICAL QUANT GRAV JI Class. Quantum Gravity PD AUG PY 1994 VL 11 IS 8 BP 2031 EP 2044 DI 10.1088/0264-9381/11/8/010 PG 14 WC Astronomy & Astrophysics; Physics, Multidisciplinary; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA PE557 UT WOS:A1994PE55700010 ER PT J AU MARENGO, JA DRUYAN, LM AF MARENGO, JA DRUYAN, LM TI VALIDATION OF MODEL IMPROVEMENTS FOR THE GISS GCM SO CLIMATE DYNAMICS LA English DT Article ID GENERAL-CIRCULATION MODELS; CLIMATE; PARAMETERIZATION; VARIABILITY; SENSITIVITY AB The general circulation model of the NASA/Goddard Institute for Space Studies (GISS GCM) was designed primarily for global climate change and climate sensitivity applications. The modelling group at GISS has developed new and more physically appropriate parameterizations of meteorological/hydrological processes which are being validated in an effort to improve the performance of the Model II version of the GISS GCM. This study discusses some preliminary evaluations of this testing based on multiple-year simulations at 4-degrees latitude by 5-degrees longitude horizontal resolution. These runs individually incorporate new formulations of the planetary boundary layer (PBL), the moist cumulus convection scheme and the ground hydrology and compare results using B-grid and C-grid numerics. The new PBL produces a realistically stronger tropical surface circulation, while the new cumulus scheme generates more realistic distributions of tropical convection and moisture. The main impact of the more sophisticated ground hydrology model is to increase surface air temperatures. Improvements in modelled sea level pressure and rainfall features by the C-grid are somewhat offset by increases in speed excesses at the cores of the summer hemisphere westerly jets. Each modelling innovation targeted a different aspect of the climate not adequately represented by Model II. However, since the various modelling changes were tested individually, the present evaluation could not demonstrate many dramatic improvements in the simulated climates. This documentation of impacts should, however, serve as a benchmark for the validation of future simulations of the GISS GCM that combine all of the modelling improvements. C1 NASA,GODDARD INST SPACE STUDIES,NATL RES COUNCIL,NEW YORK,NY 10025. COLUMBIA UNIV,NEW YORK,NY 10027. RI Marengo, Jose /J-9382-2012 OI Marengo, Jose /0000-0002-8154-2762 NR 34 TC 11 Z9 11 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0930-7575 J9 CLIM DYNAM JI Clim. Dyn. PD AUG PY 1994 VL 10 IS 3 BP 163 EP 179 DI 10.1007/BF00210627 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PA437 UT WOS:A1994PA43700003 ER PT J AU AHN, KH HOPKINS, DA AF AHN, KH HOPKINS, DA TI A GENERALIZED DOMAIN DECOMPOSITION TECHNIQUE FOR MIXED-ITERATIVE FINITE-ELEMENT FORMULATION SO COMPUTING SYSTEMS IN ENGINEERING LA English DT Article; Proceedings Paper CT 3rd National Symposium on Large-Scale Structural Analysis for High-Performance Computers and Workstations CY NOV 08-11, 1994 CL NORFOLK, VA ID PARALLEL AB A concurrent formulation for a large scale finite element problem with direct matrix solver is presented through combined use of domain decomposition and parallel matrix factorization. The algorithm not only reduces high-speed memory requirements but also generates high speed-up in matrix factorization. The present work demonstrates the efficient domain decomposition technique that minimizes the inter-processor communication using the bandwidth optimization technique which has been commonly used for stiffness matrix solution. The direct method using LDL(T) skyline factorization has been parallelized and used for each sub-region eliminating the need to form the global system for the entire domain. Implementation of the communication algorithm due to domain decomposition into the existing matrix assembly, matrix solution stage along with minimum necessary communication requirements between the processors has been presented in detail. The current domain decomposition scheme provides flexible utilization of processors depending on the user's needs for a problem. The user can assign a different number of processors for domain decomposition and matrix factorization to control the memory requirement and to control the speed-up respectively. The results obtained from IBM RS-6000 clustered workstations will be presented. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP AHN, KH (reprint author), NYMA INC,BROOKPARK,OH 44142, USA. NR 10 TC 0 Z9 0 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-0521 J9 COMPUT SYST ENG JI Comput. Syst. Eng. PD AUG-DEC PY 1994 VL 5 IS 4-6 BP 351 EP 361 DI 10.1016/0956-0521(94)90017-5 PG 11 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary SC Computer Science; Engineering GA RA471 UT WOS:A1994RA47100006 ER PT J AU WATSON, BC NOOR, AK AF WATSON, BC NOOR, AK TI POSTBUCKLING AND LARGE-DEFLECTION NONLINEAR ANALYSES ON DISTRIBUTED-MEMORY COMPUTERS SO COMPUTING SYSTEMS IN ENGINEERING LA English DT Article; Proceedings Paper CT 3rd National Symposium on Large-Scale Structural Analysis for High-Performance Computers and Workstations CY NOV 08-11, 1994 CL NORFOLK, VA ID SPARSE AB A computational strategy is presented for postbuckling and nonlinear static analyses of large complex structures on distributed-memory parallel computers. The strategy is designed for message-passing parallel computer systems. The key elements of the proposed strategy are: (a) a multiple-parameter reduced basis technique, (b) a nested dissection (or multilevel substructuring) ordering scheme, (c) parallel assembly of global matrices, and (d) a parallel sparse equation solver. The effectiveness of the strategy is assessed by performing thermomechanical postbuckling analyses of stiffened composite panels with cutouts, and nonlinear large-deflection analyses of High Speed Civil Transport models on three distributed-memory computers. The numerical studies presented demonstrate the advantages of nested dissection-based solvers over traditional skyline-based solvers on distributed-memory machines. RP WATSON, BC (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR COMPUTAT STRUCT TECHNOL,HAMPTON,VA 23665, USA. NR 24 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 0956-0521 J9 COMPUT SYST ENG JI Comput. Syst. Eng. PD AUG-DEC PY 1994 VL 5 IS 4-6 BP 389 EP 405 DI 10.1016/0956-0521(94)90021-3 PG 17 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary SC Computer Science; Engineering GA RA471 UT WOS:A1994RA47100010 ER PT J AU PATNAIK, SN GENDY, AS HOPKINS, DA AF PATNAIK, SN GENDY, AS HOPKINS, DA TI DESIGN OPTIMIZATION OF LARGE STRUCTURAL SYSTEMS WITH SUBSTRUCTURING IN A PARALLEL COMPUTATIONAL ENVIRONMENT SO COMPUTING SYSTEMS IN ENGINEERING LA English DT Article; Proceedings Paper CT 3rd National Symposium on Large-Scale Structural Analysis for High-Performance Computers and Workstations CY NOV 08-11, 1994 CL NORFOLK, VA ID MULTILEVEL AB Design optimization of large structural systems can be attempted through a substructure strategy when difficulties are encountered with convergence of such problems. In this strategy the large structure is divided into several smaller substructures, and a subproblem is defined for each substructure. Solution of the large problem can be obtained iteratively through repeated solutions of the modest subproblems. Substructure strategies, in sequential as well as in parallel computational modes on a GRAY YMP multiprocessor computer, have been incorporated into the code CometBoards, which is an acronym for Comparative Evaluation Test Bed of Optimization and Analysis Routines for Design of Structures. Three issues, intensive computation, convergence of the iterative process, and analytically superior optimum, encountered during the implementation of substructure optimization into CometBoards have been solved. Coupling between subproblems as well as local and global constraints grouping are essential for convergence of the iterative process. The substructure strategy can produce an analytically superior optimum different from what can be obtained by regular optimization. For the problems solved, substructure optimization in a parallel computational mode made effective use of all assigned processors. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP PATNAIK, SN (reprint author), OHIO AEROSP INST,CLEVELAND,OH 44142, USA. NR 19 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 0956-0521 J9 COMPUT SYST ENG JI Comput. Syst. Eng. PD AUG-DEC PY 1994 VL 5 IS 4-6 BP 425 EP 440 DI 10.1016/0956-0521(94)90024-8 PG 16 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary SC Computer Science; Engineering GA RA471 UT WOS:A1994RA47100013 ER PT J AU STORAASLI, OO HOUSNER, JM AF STORAASLI, OO HOUSNER, JM TI SPECIAL ISSUE - LARGE-SCALE STRUCTURAL-ANALYSIS FOR HIGH-PERFORMANCE COMPUTERS AND WORKSTATIONS - PREFACE SO COMPUTING SYSTEMS IN ENGINEERING LA English DT Editorial Material RP STORAASLI, OO (reprint author), NASA,LANGLEY RES CTR,COMPUTAT STRUCT BRANCH,HAMPTON,VA 23681, USA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-0521 J9 COMPUT SYST ENG JI Comput. Syst. Eng. PD AUG-DEC PY 1994 VL 5 IS 4-6 BP R5 EP R6 DI 10.1016/0956-0521(94)90012-4 PG 2 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary SC Computer Science; Engineering GA RA471 UT WOS:A1994RA47100001 ER PT J AU LITTLE, B RAY, R HART, K WAGNER, P AF LITTLE, B RAY, R HART, K WAGNER, P TI FUNGAL-INDUCED CORROSION OF WIRE ROPE EXPOSED IN HUMID ATMOSPHERIC CONDITIONS SO CORROSION PREVENTION & CONTROL LA English DT Article AB Localized corrosion of carbon-steel wire rope stored in a humid environment on wooden spools was caused by the production of organic acid and carbon dioxide by fungi growing directly on the wood. Fungal growth was observed on the interiors of wooden spools, and corrosion was most severe on the wrap of wire in direct contact with the wood. Laboratory experiments were designed to demonstrate a causal relationship between storage conditions, fungal growth and localized corrosion. RP LITTLE, B (reprint author), USN,RES LAB,STENNIS SPACE CTR,WASHINGTON,DC 20375, USA. NR 17 TC 3 Z9 3 U1 0 U2 0 PU SCIENTIFIC SURVEYS LTD PI BEACONSFIELD PA PO BOX 21, BEACONSFIELD, BUCKS, ENGLAND HP9 1NS SN 0010-9371 J9 CORROS PREVENT CONTR JI Corrosion Prev. Control PD AUG PY 1994 VL 41 IS 4 BP 89 EP 93 PG 5 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA PG591 UT WOS:A1994PG59100004 ER PT J AU SALERNO, LJ KITTEL, P SPIVAK, AL AF SALERNO, LJ KITTEL, P SPIVAK, AL TI THERMAL CONDUCTANCE OF PRESSED METALLIC CONTACTS AUGMENTED WITH INDIUM FOIL OR APIEZON GREASE AT LIQUID-HELIUM TEMPERATURES SO CRYOGENICS LA English DT Article DE THERMAL CONDUCTANCE; PRESSED METALLIC CONTACTS; LIQUID HELIUM TEMPERATURES AB The thermal conductance of pressed contacts which have been augmented with indium foil or Apiezon-N(TM) grease has been measured over the temperature range 1.6-6.0 K, with applied forces from 22 to 670 N. The sample pairs were fabricated from OFHC copper, 6061-T6 aluminium, free-machining brass and 304 stainless steel. Although the thermal conductance was found to increase with increasing applied contact force, the force dependence was less than in earlier work. The addition of indium foil or Apiezon grease between the contact surfaces resulted in an improvement over uncoated surfaces ranging from approximately a factor of 3 for stainless steel to an order of magnitude for copper contacts. C1 TRANSBAY ELECTR,RICHMOND,CA 94804. RP SALERNO, LJ (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 8 TC 16 Z9 18 U1 1 U2 4 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0011-2275 J9 CRYOGENICS JI Cryogenics PD AUG PY 1994 VL 34 IS 8 BP 649 EP 654 DI 10.1016/0011-2275(94)90142-2 PG 6 WC Thermodynamics; Physics, Applied SC Thermodynamics; Physics GA NZ826 UT WOS:A1994NZ82600004 ER PT J AU CHEN, CK AF CHEN, CK TI NEW SENSING TECHNIQUES IMPROVE GALAXY EXPLORATION - SEARCHING FOR ET SIGNALS SO EE-EVALUATION ENGINEERING LA English DT Article RP CHEN, CK (reprint author), NASA,AMES RES CTR,SILICON ENGINES,M-S 244-11,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU NELSON PUBLISHING PI NOKOMIS PA 2504 NORTH TAMIAMI TRAIL, NOKOMIS, FL 34275-3482 SN 0149-0370 J9 EE-EVAL ENG JI EE-Eval. Eng. PD AUG PY 1994 VL 33 IS 8 BP 98 EP & PG 0 WC Engineering, Electrical & Electronic SC Engineering GA PX023 UT WOS:A1994PX02300009 ER PT J AU BEAL, KL AF BEAL, KL TI EXAMINING ETHICS SO FISHERIES LA English DT Article RP BEAL, KL (reprint author), NATL MARINE FISHERIES SERV,1 BLACKBURN DR,GLOUCESTER,MA 01930, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 SN 0363-2415 J9 FISHERIES JI Fisheries PD AUG PY 1994 VL 19 IS 8 BP 41 EP 41 PG 1 WC Fisheries SC Fisheries GA NY867 UT WOS:A1994NY86700015 ER PT J AU IRION, FW BROWN, M TOON, GC GUNSON, MR AF IRION, FW BROWN, M TOON, GC GUNSON, MR TI INCREASE IN ATMOSPHERIC CHF2CL(HCFC-22) OVER SOUTHERN CALIFORNIA FROM 1985 TO 1990 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOURCE GASES; STRATOSPHERE; EMISSIONS; TRANSPORT; CHLORINE; HCFC-22; MODEL AB Column densities of CHF2Cl (HCFC-22) have been measured over Table Mountain Facility (TMF), Wrightwood, California (34.4-degrees-N) using the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier-transform infrared (FTIR) spectrometer. Between October 1985 and July 1990, the exponential column increase rate was (6.7+/-0.5)% yr-1 Additionally, column measurements of CHF2Cl over McMurdo Sound, Antarctica (78-degrees-S) in September and October 1986 by the MarkIV FTIR spectrometer were used to derive a south-north interhemispheric ratio of (0.86+/-0.08). Model calculations investigated the feasibility of using CHF2Cl column measurements with a predicted global OH field to determine a globally averaged chemical lifetime for CHF2Cl, or equivalently, an estimate of the OH field using a predicted lifetime. The current uncertainty in historical CHF2Cl emissions is too large for CHF2Cl to be used to infer adequately either the lifetime or the OH field. C1 JET PROP LAB,PASADENA,CA 91109. UNIV WASHINGTON,DEPT APPL MATH,SEATTLE,WA 98195. RP IRION, FW (reprint author), CALTECH,DEPT CHEM ENGN,PASADENA,CA 91125, USA. NR 21 TC 12 Z9 12 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD AUG 1 PY 1994 VL 21 IS 16 BP 1723 EP 1726 DI 10.1029/94GL01323 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PA722 UT WOS:A1994PA72200015 ER PT J AU GAZIS, PR AF GAZIS, PR TI PIONEER AND VOYAGER OBSERVATIONS OF SOLAR-CYCLE VARIATIONS IN THE OUTER HELIOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LATITUDE DEPENDENCE; LONGITUDE STRUCTURE; WIND; SPEED; MINIMUM; STREAM AB Solar wind measurements from the Pioneer 10, Pioneer 11, and Voyager 2 spacecraft are now available through mid-1993. These measurements extend our knowledge of the outer heliosphere to heliographic latitudes that range between -10-degrees and 17.5-degrees, and provide insight into the variation with solar cycle of the structure of the distant solar wind. The average temperature, mass flux density, dynamic pressure, and kinetic and thermal energy flux densities varied strongly with solar cycle at the latitude of Pioneer 11 (10-degrees to 17-degrees N), but were almost constant in the vicinity of the solar equator. These parameters may have increased with latitude between the solar equator and 17-degrees-N. There was also a short-term variation in average solar wind parameters near the time of the 1986 solar minimum, when the inclination of the heliospheric current sheet dropped below the latitude of Pioneer 11. RP GAZIS, PR (reprint author), SAN JOSE STATE UNIV FDN,NASA,AMES RES CTR,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 19 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 AUG 1 PY 1994 VL 21 IS 16 BP 1743 EP 1746 DI 10.1029/94GL01428 PG 4 WC Geosciences, Multidisciplinary SC Geology GA PA722 UT WOS:A1994PA72200020 ER PT J AU SCHEERES, DJ AF SCHEERES, DJ TI DYNAMICS ABOUT UNIFORMLY ROTATING TRIAXIAL ELLIPSOIDS - APPLICATIONS TO ASTEROIDS SO ICARUS LA English DT Article ID ORBITAL STABILITY ZONES; SATELLITES AB The general problem of satellite and particle dynamics about a uniformly rotating triaxial ellipsoid with constant density is formulated. The study of this problem can shed light on the dynamics of particles and satellites when orbiting irregularly shaped bodies such as asteroids. The physical specification of an asteroid modeled as a triaxial ellipsoid can be reduced to two nondimensional shape parameters (the eccentricities of the triaxial ellipsoid) and one nondimensional parameter which is a function of the body density, shape, and rotation rate. All these parameters may be measured or inferred from groundbased observations. Using these three parameters, the rotating ellipsoid may be classified into Type I or Type II ellipsoids depending on whether or not all synchronous orbits about the body are unstable. This classification of the ellipsoid has significant consequences for the dynamics of bodies in orbits which are near-synchronous with the asteroid rotation. Asteroids classified as Type I have stable motion associated with near-synchronous orbits. Asteroids classified as Type II have unstable motion associated with near-synchronous orbits. Families of planar periodic orbits are computed for two specific ellipsoids based on the asteroids Vesta and Eros. The stability of these families are computed and related to the type classification of the ellipsoid. Notes are also made on the existence of stable and unstable periodic orbits about the asteroid Ida. Analytic approximations are also introduced under some assumptions, leading to a simplified description of orbits about a triaxial ellipsoid. Finally, a table of parameters and classifications for a few known asteroids and comets are given. (C) 1994 Academic Press. Inc. RP SCHEERES, DJ (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 28 TC 128 Z9 134 U1 2 U2 13 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1994 VL 110 IS 2 BP 225 EP 238 DI 10.1006/icar.1994.1118 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK621 UT WOS:A1994PK62100004 ER PT J AU SANDFORD, SA GEBALLE, TR SALAMA, F GOORVITCH, D AF SANDFORD, SA GEBALLE, TR SALAMA, F GOORVITCH, D TI NEW NARROW INFRARED-ABSORPTION FEATURES IN THE SPECTRUM OF IO BETWEEN 3600 AND 3100 CM(-1) (2.8-3.2-MU-M) SO ICARUS LA English DT Article ID SURFACE; FROST; SO2; IDENTIFICATION; CO2 AB We report the discovery of a series of infrared absorption bands between 3600 and 3100 cm-1 (2.8-3.2 mum) in the spectrum of Io. Individual narrow bands are detected at 3553, 3514.5, 3438, 3423, 3411.5, and 3401 cm-1 (2.815, 2.845, 2.909, 2.921, 2.931, and 2.940 mum, respectively). The positions and relative strengths of these bands, and the difference of their absolute strengths between the leading and trailing faces of Io, indicate that they are due to SO2. The band at 3438 cm-1 (2.909 mum) could potentially have a contribution from an additional molecular species. The existence of these bands in the spectrum of Io indicates that a substantial fraction of the SO2 on Io must reside in transparent ices having relatively large crystal sizes. The decrease in the continuum observed at the high frequency ends of the spectra is probably due to the low frequency side of the recently detected, strong 3590 cm-1 (2.79 mum) feature. This band is likely due to the combination of a moderately strong SO2 band and an additional absorption from another molecular species, perhaps H2O isolated in SO2 at low concentrations. A broad (FWHM almost-equal-to 40-60 cm-1), weak band is seen near 3160 cm-1 (3.16 mum) and is consistent with the presence of small quantities of H2O isolated in SO2-rich ices. There is no evidence in the spectra for the presence of H2O vapor on Io. Thus, the spectra presented here neither provide unequivocal evidence for the presence of H2O on Io nor preclude it at the low concentrations suggested by past studies. (C) 1994 Academic Press, Inc. C1 JOINT ASTRON CTR,HILO,HI 96720. RP SANDFORD, SA (reprint author), NASA,AMES RES CTR,MAIL STOP 245-6,MOFFETT FIELD,CA 94035, USA. NR 31 TC 5 Z9 5 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1994 VL 110 IS 2 BP 292 EP 302 DI 10.1006/icar.1994.1123 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK621 UT WOS:A1994PK62100009 ER PT J AU BURATTI, BJ GOGUEN, JD GIBSON, J MOSHER, J AF BURATTI, BJ GOGUEN, JD GIBSON, J MOSHER, J TI HISTORICAL PHOTOMETRIC EVIDENCE FOR VOLATILE MIGRATION ON TRITON SO ICARUS LA English DT Article ID POLAR CAPS; SATELLITES; ATMOSPHERE; NITROGEN; VOYAGER-2; STABILITY; NEPTUNE; RINGS; MODEL AB Analysis of CCD images of Triton obtained with the 1.5-m telescope on Palomar Mountain shows that in the time period surrounding the Voyager 2 encounter with the satellite (1985-1990), no changes in the satellite's visual albedo or color occurred. The published observations of Triton in the 0.35- to 0.60-mum spectral region obtained between 1950 and 1990 were reanalyzed to detect historical variability in both its albedo and visual color. Analysis of the photometry indicates that there is little, if any, change in Triton's visual geometric albedo. This result is consistent with the albedo pattern observed by Voyager and the change in sub-Earth latitude. Two distinct types of color changes are evident: a significant secular increase in the blue region of the visual spectrum since at least the 1950s, and the reported dramatic reddening of Triton's spectrum in the late 1970s. The latter change can be explained only by a short-lived geological phenomenon. Triton's changing pole orientation with respect to a terrestrial observer cannot explain the secular color changes. These changes imply volatile transport on a global scale on Triton's surface during the past 4 decades. We present two models which show that either removal of a red volatile from Triton's polar cap or deposition of a blue volatile in the equatorial regions can explain the secular color changes. A third possibility is that the changes are the result of the alpha-beta phase transition of nitrogen and subsequent fracturing of the polar cap region (N. S. Duxburv and R. H. Brown, 1993, Science 261, 748). (C) 1994 Academic Press, Inc. C1 CALTECH,PALOMAR OBSERV,PASADENA,CA 91125. RP BURATTI, BJ (reprint author), JET PROP LAB,183501,PASADENA,CA 91109, USA. NR 38 TC 19 Z9 19 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD AUG PY 1994 VL 110 IS 2 BP 303 EP 314 DI 10.1006/icar.1994.1124 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PK621 UT WOS:A1994PK62100010 ER PT J AU WOO, A VOLAKIS, J HULBERT, G CASE, J AF WOO, A VOLAKIS, J HULBERT, G CASE, J TI SURVEY OF VOLUMETRIC-GRID GENERATORS SO IEEE ANTENNAS AND PROPAGATION MAGAZINE LA English DT Article C1 UNIV MICHIGAN,DEPT EECS,ANN ARBOR,MI 48109. RP WOO, A (reprint author), NASA,AMES RES CTR,MAIL STOP 227-6,MOFFETT FIELD,CA 94035, USA. NR 0 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 1045-9243 J9 IEEE ANTENNAS PROPAG JI IEEE Antennas Propag. Mag. PD AUG PY 1994 VL 36 IS 4 BP 72 EP 75 PG 4 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA PT614 UT WOS:A1994PT61400016 ER PT J AU SCHUH, MJ WOO, AC SIMON, MP AF SCHUH, MJ WOO, AC SIMON, MP TI THE MONOSTATIC BISTATIC APPROXIMATION SO IEEE ANTENNAS AND PROPAGATION MAGAZINE LA English DT Note AB Many Radar Cross Section (RCS) prediction codes are limited to one monostatic return per run. However, such codes can calculate multiple bistatic returns per incident angle for a relatively small amount of additional computer resources. This note describes a method of using bistatic returns to generate multiple monostatic predictions for each incident angle computed. Typical results are presented, and show that the accuracy is initially high, and then degrades as the separation angle between the incident and viewing angles becomes large. C1 STERLING SOFTWARE,MOFFETT FIELD,CA 94035. RP SCHUH, MJ (reprint author), NASA,AMES RES CTR,MAIL STOP 227-6,MOFFETT FIELD,CA 94035, USA. NR 5 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 1045-9243 J9 IEEE ANTENNAS PROPAG JI IEEE Antennas Propag. Mag. PD AUG PY 1994 VL 36 IS 4 BP 76 EP 78 DI 10.1109/74.317796 PG 3 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA PT614 UT WOS:A1994PT61400017 ER PT J AU SMITH, RP ALLEN, ST REDDY, M MARTIN, SC LIU, J MULLER, RE RODWELL, MJW AF SMITH, RP ALLEN, ST REDDY, M MARTIN, SC LIU, J MULLER, RE RODWELL, MJW TI 0.1-MU-M SCHOTTKY-COLLECTOR ALAS/GAAS RESONANT-TUNNELING DIODES SO IEEE ELECTRON DEVICE LETTERS LA English DT Article ID OSCILLATIONS; GHZ AB The Schottky-collector resonant tunneling diode (RTD) is an RTD with the normal N+ collector and ohmic contact replaced by a Schottky contact, thereby eliminating the associated parasitic resistance. With submicron Schottky contact dimensions, the remaining components of the parasitic series resistance can be greatly reduced, resulting in an increased maximum frequency of oscillation, f(max). AlAs/GaAs Schottky-collector RTDs were fabricated using 0.1 mum T-gate technology developed for high electron mobility transistors. From their measured dc and microwave parameters, and including the effect of the quantum well lifetime, f(max) = 900 GHz is computed. C1 UNIV CALIF SANTA BARBARA,DEPT ELECT & COMP ENGN,SANTA BARBARA,CA 93106. RP SMITH, RP (reprint author), JET PROP LAB,CTR SPACE MICROELECTR,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 TC 27 Z9 28 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 0741-3106 J9 IEEE ELECTR DEVICE L JI IEEE Electron Device Lett. PD AUG PY 1994 VL 15 IS 8 BP 295 EP 297 DI 10.1109/55.296221 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA PB031 UT WOS:A1994PB03100011 ER PT J AU BERENJI, HR AF BERENJI, HR TI THE UNIQUE STRENGTH OF FUZZY-LOGIC CONTROL SO IEEE EXPERT-INTELLIGENT SYSTEMS & THEIR APPLICATIONS LA English DT Article RP BERENJI, HR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 5 TC 4 Z9 5 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0885-9000 J9 IEEE EXPERT JI IEEE Expert-Intell. Syst. Appl. PD AUG PY 1994 VL 9 IS 4 BP 9 EP 9 PG 1 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA PM816 UT WOS:A1994PM81600003 ER PT J AU YOUNG, PG SIMONS, RN ALTEROVITZ, SA ROMANOFSKY, RR SMITH, ED AF YOUNG, PG SIMONS, RN ALTEROVITZ, SA ROMANOFSKY, RR SMITH, ED TI RF CONTROL OF EPITAXIAL LIFT-OFF PHEMTS UNDER BACKSIDE ILLUMINATION SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article ID MICROWAVE AB This paper presents the optical response of the DC and the RF (C-Band) performance of a 1 mum gate length epitaxial lift-off PHEMT device under backside illumination. The device when biased near pinch off exhibited an increase of S21, G(max), and g(m) of 1.2 dB, 2 dB, and 56%, respectively. The measured responsivity was as high as 13.4 A/W with a quantum efficiency of 2300 percent. These results far exceeded previously reported performances for devices under frontside illumination. C1 UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 6 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD AUG PY 1994 VL 30 IS 8 BP 1782 EP 1786 DI 10.1109/3.301642 PG 5 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA PC197 UT WOS:A1994PC19700013 ER PT J AU BARRY, A SHEPPARD, D AF BARRY, A SHEPPARD, D TI HIGH-SPEED DATA-ACQUISITION SYSTEM FOR LARGE-AREA PROPORTIONAL-COUNTERS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT Nuclear Science Symposium and Medical Imaging Conference (NSS-MIC 93) CY OCT 30-NOV 06, 1993 CL SAN FRANCISCO, CA SP IEEE AB A modular, UNIX/X-Windows/Sun SPARC-based data acquisition and analysis system provides NASA X-Ray Timing Explorer (XTE) Proportional Counter Array (PCA) scientists with near real-time access to space flight instrument ground test data. This system processes data directly from five large-area, xenon-filled low-background collimated proportional counters at rates up to 2 MB/s in a networked, real-time environment. Science events are sent serially from the proportional counter flight electronics and multiplexed on a custom-designed data acquisition board. Each event is tagged with a time stamp of 1 mus resolution and a detector identifier. A commercial Direct Memory Access (DMA) board interfaces directly to the data acquisition board allowing asynchronous transfer of buffered data to software residing on a high performance workstation. A windows-based interface provides an operator with acquisition command and control functions to capture data through the DMA board. Data is collected, buffered, and archived to magnetic disk. Histogramming and statistical functions are provided by the software enabling real-time pulse height spectroscopy, rate analysis, and spectral analysis. RP BARRY, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 7 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD AUG PY 1994 VL 41 IS 4 BP 1304 EP 1308 DI 10.1109/23.322904 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PE028 UT WOS:A1994PE02800123 ER PT J AU ZHANG, SN FISHMAN, GJ HARMON, BA PACIESAS, WS MEEGAN, CA WILSON, RB FINGER, MH RUBIN, BC AF ZHANG, SN FISHMAN, GJ HARMON, BA PACIESAS, WS MEEGAN, CA WILSON, RB FINGER, MH RUBIN, BC TI A MASKLESS GAMMA-RAY ALL-SKY IMAGER - BATSE CGRO SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT Nuclear Science Symposium and Medical Imaging Conference (NSS-MIC 93) CY OCT 30-NOV 06, 1993 CL SAN FRANCISCO, CA SP IEEE ID GALACTIC-CENTER AB The non-collimated detectors of BATSE (Burst And Transient Source Experiment) on the Compton Gamma Ray Observatory (CGRO) can be used as a high sensitivity hard X-ray and low energy gamma-ray all-sky imager in the energy range between 20 keV and 2 MeV. The fluxes from sources in the sky are modulated as the spacecraft orbits the Earth. The CGRO orbital precession further allows sampling of sky in strips corresponding to the limb of the earth at any given time. The modulation data are transformed into images by various reconstruction methods. High sensitivity images of location accuracy of about 0.1-degree and source seperation of about 1-degree are obtained. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV ALABAMA,HUNTSVILLE,AL 35899. RP ZHANG, SN (reprint author), UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35806, USA. NR 28 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD AUG PY 1994 VL 41 IS 4 BP 1313 EP 1320 DI 10.1109/23.322906 PN 1 PG 8 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PE028 UT WOS:A1994PE02800125 ER PT J AU HUBBARD, GS MCMURRAY, RE KELLER, RG WERCINSKI, PF WALTON, JT WONG, YK AF HUBBARD, GS MCMURRAY, RE KELLER, RG WERCINSKI, PF WALTON, JT WONG, YK TI VARIABLE-TEMPERATURE PERFORMANCE OF A SI(LI) DETECTOR STACK SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT Nuclear Science Symposium and Medical Imaging Conference (NSS-MIC 93) CY OCT 30-NOV 06, 1993 CL SAN FRANCISCO, CA SP IEEE AB New experimental data is presented which displays Cs-137 resolution of both single Si(Li) devices and a detector stack 2 cm in height as a function of temperature (85 K less-than-or-equal-to T less-than-or-equal-to 245 K). We also discuss variations in photopeak shape which indicate that detector charge collection may be temperature dependent over the range of interest. C1 LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. RP HUBBARD, GS (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 3 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD AUG PY 1994 VL 41 IS 4 BP 1338 EP 1342 DI 10.1109/23.322910 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PE028 UT WOS:A1994PE02800129 ER PT J AU GLASSER, CA ODELL, CE SEUFERT, SE AF GLASSER, CA ODELL, CE SEUFERT, SE TI THE PROPORTIONAL COUNTER ARRAY (PCA) INSTRUMENT FOR THE X-RAY TIMING EXPLORER SATELLITE (XTE) SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article; Proceedings Paper CT Nuclear Science Symposium and Medical Imaging Conference (NSS-MIC 93) CY OCT 30-NOV 06, 1993 CL SAN FRANCISCO, CA SP IEEE AB A large area array of Xenon gas filled proportional counters has been developed as the main instrument of the X-ray Timing Explorer (XTE) satellite. The array is composed of 5 independent detectors, each operating in the energy range of 2-60 keV. Each detector provides event information timed to 1-microsecond, and spectral resolution of approximately 18% FWHM at 6 keV. This paper will describe the overall design of the detector and associated electronic system, their performance, and calibration results. RP GLASSER, CA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 0 TC 11 Z9 12 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 AUG PY 1994 VL 41 IS 4 BP 1343 EP 13485 DI 10.1109/23.322911 PN 1 PG 12143 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA PE028 UT WOS:A1994PE02800130 ER PT J AU GAT, E DESAI, R IVLEV, R LOCH, J MILLER, DP AF GAT, E DESAI, R IVLEV, R LOCH, J MILLER, DP TI BEHAVIOR CONTROL FOR ROBOTIC EXPLORATION OF PLANETARY SURFACES SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article AB This paper describes a series of robots developed at JPL to demonstrate the feasibility of using a behavior-control approach to control small robots on planetary surfaces. The round-trip light-time delay makes direct teleoperation of a mobile robot on a planetary surface impossible. Planetary rovers must therefore possess a certain degree of autonomy. However, small robots can only support small computers (due mostly to power, not size constraints). Behavior Control provides a means of autonomous control that requires very little computation. The robots described in this paper all used 8-bit, 1-MIP microprocessors with as little as 4 k and no more than 40 k of memory, and extremely simple sensors. Despite these limitations they reliably perform both autonomous navigation and manipulation in both indoor and outdoor rough-terrain environments. C1 CALTECH,DEPT MECH ENGN,PASADENA,CA 91125. RP GAT, E (reprint author), JET PROP LAB,TECH STAFF,INTELLIGENT EMBEDDED SYST GRP,PASADENA,CA 91109, USA. NR 20 TC 57 Z9 60 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 1042-296X J9 IEEE T ROBOTIC AUTOM JI IEEE Trans. Robot. Autom. PD AUG PY 1994 VL 10 IS 4 BP 490 EP 503 DI 10.1109/70.313099 PG 14 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA PC662 UT WOS:A1994PC66200008 ER PT J AU BLAES, BR BUEHLER, MG AF BLAES, BR BUEHLER, MG TI SEU SRAM AS A PROCESS MONITOR SO IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING LA English DT Article; Proceedings Paper CT International Conference on Microelectronic Test Structures (ICMTS) CY MAR 22-25, 1993 CL SITGES, SPAIN SP IEEE, ELECTRON DEVICES SOC AB The SEU/SRAM is a 4-kbit static random access memory (SRAM) designed to detect single-event upsets (SEU's) produced by high-energy particles, either in space or on the ground. This device was used to determine the distribution of the memory cell spontaneous flip potential. The variance in this potential was determined to be due to the variation in the threshold voltage of one of the n-FET's found in the memory cell. For a 1.2-mum CMOS process, the standard deviation of the n-FET VT was found to be 8 mV. This structure provides substantial statistical data; 4096 data points are measured. Using cumulative distribution and residual plots, outlier cells, such as stuck cells and nonnormally distributed cells, are easily identified. RP BLAES, BR (reprint author), JET PROP LAB,VLSI TECHNOL GRP,PASADENA,CA 91109, USA. NR 8 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0894-6507 J9 IEEE T SEMICONDUCT M JI IEEE Trans. Semicond. Manuf. PD AUG PY 1994 VL 7 IS 3 BP 319 EP 324 DI 10.1109/66.311335 PG 6 WC Engineering, Manufacturing; Engineering, Electrical & Electronic; Physics, Applied; Physics, Condensed Matter SC Engineering; Physics GA PE203 UT WOS:A1994PE20300012 ER PT J AU CHEW, KC SONI, T ZEIDLER, JR KU, WH AF CHEW, KC SONI, T ZEIDLER, JR KU, WH TI TRACKING MODEL OF AN ADAPTIVE LATTICE FILTER FOR A LINEAR CHIRP FM SIGNAL IN NOISE SO IEEE TRANSACTIONS ON SIGNAL PROCESSING LA English DT Article ID MULTIPLE SINUSOIDS; LMS; PERFORMANCE; ENHANCER; ALGORITHM; RECOVERY AB This paper studies the behavior of the partial correlation (PARCOR) coefficients and the output misadjustment of the stochastic gradient adaptive lattice filter in response to a complex linear chirp FM signal in white Gaussian noise. Analytic expressions for the optimal PARCOR coefficients of the filter are derived. Analytic as well as iterative models for a three-stage filter are also derived. The analytic expressions show that the tracking and convergence properties of the filter are separate phenomena. Simulation results also show that the spectral contents of the PARCOR coefficients for the stochastic gradient update algorithm consist of a stationary and a linearly swept component. A single-stage model is developed to explain this behavior. Finally, output misadjustment plots for the filter show that an optimum value for the forgetting factor can be obtained to minimize the misadjustment, but the value required to achieve local minimum misadjustment varies with each stage of the filter. It is shown that in applications where the input has a high signal-to-noise ratio (SNR), the misadjustment decreases rapidly at each successive stage, thus implying that relatively short filter lengths are sufficient to provide effective tracking. C1 NASA,AMES RES CTR,STERLING SOFTWARE,MOFFETT FIELD,CA 94035. NAVAL COMMAND CONTROL & OCEAN SURVEILLANCE CTR,DIV RDT&E,SAN DIEGO,CA 92152. UNIV CALIF SAN DIEGO,CTR ULTRA HIGH SPEED INTEGRATED CIRCUITS & SYST,LA JOLLA,CA 92093. RP CHEW, KC (reprint author), SIONG HOE INT,SINGAPORE,SINGAPORE. NR 27 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 1053-587X J9 IEEE T SIGNAL PROCES JI IEEE Trans. Signal Process. PD AUG PY 1994 VL 42 IS 8 BP 1939 EP 1951 DI 10.1109/78.301832 PG 13 WC Engineering, Electrical & Electronic SC Engineering GA PB601 UT WOS:A1994PB60100003 ER PT J AU WOOD, JC BARRY, DT AF WOOD, JC BARRY, DT TI TOMOGRAPHIC TIME-FREQUENCY ANALYSIS AND ITS APPLICATION TOWARD TIME-VARYING FILTERING AND ADAPTIVE KERNEL DESIGN FOR MULTICOMPONENT LINEAR-FM SIGNALS SO IEEE TRANSACTIONS ON SIGNAL PROCESSING LA English DT Article ID WIGNER DISTRIBUTION; DOPPLER RADAR AB Since line integrals through the Wigner spectrum can be calculated by dechirping, calculation of the Wigner spectrum may be viewed as a tomographic reconstruction problem. In this paper, we show that all time-frequency transforms of Cohen's class may be achieved by simple changes in backprojection reconstruction filtering. The resolution/cross-term tradeoff that occurs in time-frequency kernel selection is shown to be analogous to the resolution-ringing tradeoff that occurs in computed tomography (CT). ''Ideal'' reconstruction using a purely differentiating backprojection filter yields the Wigner distribution, whereas low-pass differentiating filters produce cross-term suppressing distributions such as the spectrogram or the Born-Jordan distribution. It is also demonstrated how this analogy can be exploited to ''tune'' the reconstruction filtering (or time-frequency kernel) to improve the ringing/resolution tradeoff. Some properties of the projection domain, which is also known as the Radon-Wigner transform, are characterized, including the response to signal delays or frequency shifts and projection masking or convolution. Last, time-varying filtering by shift-varying convolution in the Radon-Wigner domain is shown to yield superior results to its analogous Cohen's class adaptive transform (shift-invariant convolution) for the multicomponent, linear-FM signals that are investigated. C1 UNIV MICHIGAN,SCH MED,DEPT PM & R,ANN ARBOR,MI 48104. NASA,LYNDON B JOHNSON SPACE CTR,ASTRONAUT OFF,HOUSTON,TX 77058. UNIV MICHIGAN,SCH MED,DIV BIOENGN,ANN ARBOR,MI 48104. NR 31 TC 56 Z9 59 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 1053-587X J9 IEEE T SIGNAL PROCES JI IEEE Trans. Signal Process. PD AUG PY 1994 VL 42 IS 8 BP 2094 EP 2104 DI 10.1109/78.301844 PG 11 WC Engineering, Electrical & Electronic SC Engineering GA PB601 UT WOS:A1994PB60100016 ER PT J AU WOOD, JC BARRY, DT AF WOOD, JC BARRY, DT TI LINEAR SIGNAL SYNTHESIS USING THE RADON-WIGNER TRANSFORM SO IEEE TRANSACTIONS ON SIGNAL PROCESSING LA English DT Article AB Thresholding the Radon-Wigner transform (RWT) followed by filtered backprojection to the time-frequency plane reduces noise and cross-term power for multicomponent linear-FM signals. Although the RWT is bilinear, it may be calculated as the magnitude-squared of two linear functions. In this paper, we derive a linear synthesis algorithm from the RWT and demonstrate its efficacy. C1 UNIV MICHIGAN,SCH MED,DEPT PM&R,ANN ARBOR,MI 48104. NASA,LYNDON B JOHNSON SPACE CTR,ASTRONAUT OFF,HOUSTON,TX 77058. UNIV MICHIGAN,SCH MED,BIOENGN PROGRAM,ANN ARBOR,MI 48104. NR 7 TC 91 Z9 112 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 1053-587X J9 IEEE T SIGNAL PROCES JI IEEE Trans. Signal Process. PD AUG PY 1994 VL 42 IS 8 BP 2105 EP 2111 DI 10.1109/78.301845 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA PB601 UT WOS:A1994PB60100017 ER PT J AU SPENCER, RW HOOD, RE LAFONTAINE, FJ SMITH, EA PLATT, R GALLIANO, J GRIFFIN, VL LOBL, E AF SPENCER, RW HOOD, RE LAFONTAINE, FJ SMITH, EA PLATT, R GALLIANO, J GRIFFIN, VL LOBL, E TI HIGH-RESOLUTION IMAGING OF RAIN SYSTEMS WITH THE ADVANCED MICROWAVE PRECIPITATION RADIOMETER SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article AB An Advanced Microwave Precipitation Radiometer (AMPR) has been developed and flown in the NASA ER-2 high-altitude aircraft for imaging various atmospheric and surface processes, primarily the internal structure of rain clouds. The AMPR is a scanning four-frequency total power microwave radiometer that is externally calibrated with high-emissivity warm and cold loads. Separate antenna systems allow the sampling of the 10.7- and 19.35-GHz channels at the same spatial resolution, while the 37.1- and 85.5-GHz channels utilize the same multifrequency feedhorn as the 19.35-GHz channel. Spatial resolutions from an aircraft altitude of 20-km range from 0.6 km at 85.5 GHz to 2.8 km at 19.35 and 10.7 GHz. All channels are sampled every 0.6 km in both along-track and cross-track directions, leading to a contiguous sampling pattern of the 85.5-GHz 3-dB beamwidth footprints, 2.3x oversampling of the 37.1-GHz data, and 4.4x oversampling of the 19.35- and 10.7-GHz data. Radiometer temperature sensitivities range from 0.2-degrees to 0.5-degrees-C. Details of the system are described, including two different calibration systems and their effect on the data collected. Examples of oceanic rain systems are presented from Florida and the tropical west Pacific that illustrate the wide variety of cloud water, rainwater, and precipitation-size ice combinations that are observable from aircraft altitudes. C1 Florida State Univ, Dept Meteorol, Tallahassee, FL 32306 USA. RP SPENCER, RW (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, DIV EARTH SCI & APPLICAT, HUNTSVILLE, AL 35812 USA. NR 0 TC 51 Z9 51 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0739-0572 J9 J ATMOS OCEAN TECH JI J. Atmos. Ocean. Technol. PD AUG PY 1994 VL 11 IS 4 BP 849 EP 857 DI 10.1175/1520-0426(1994)011<0849:HRIORS>2.0.CO;2 PN 1 PG 9 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA NZ607 UT WOS:A1994NZ60700001 ER PT J AU CHAN, KL MAYR, HG MENGEL, JG HARRIS, I AF CHAN, KL MAYR, HG MENGEL, JG HARRIS, I TI A SPECTRAL APPROACH FOR STUDYING MIDDLE AND UPPER ATMOSPHERIC PHENOMENA SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT COSPAR/SCOSTEP Meeting on Mesosphere-Lower Thermosphere Coupling Study CY AUG, 1992 CL WASHINGTON, DC SP COSPAR, SCOSTEP ID THERMOSPHERIC GENERAL-CIRCULATION; ZONAL MEAN CIRCULATION; GRAVITY-WAVE; NUMERICAL-MODEL; TIDES; MESOSPHERE; SOLSTICE; SIMULATION; COMPONENT; BREAKDOWN AB We report on the application of a newly developed spectral code to the study of the middle upper atmosphere. The spectral approach offers conceptual and practical convenience for analyzing the generation and interaction of different components of atmospheric activity through the decomposition of the dynamical fields into components with different zonal wave numbers (m). As examples and tests. we obtain solutions for the m = 0 (the mean circulation) and 1 (the diurnal tides) components separately (no mutual interactions), as well as the m = 1 component under the influence of the mean circulation. By simulating gravity wave effects with Rayleigh friction and eddy diffusion peaking near 90 km altitude, the mean circulation thus generated can reproduce the observed mesospheric temperature anomaly under solstice conditions. The computed diurnal tides are in good agreement with results obtained earlier by other authors. The large temperature gradient (associated with the m = 0 component) set up by the mesospheric temperature anomaly under solstice conditions creates a condition favorable for the development of baroclinic instabilities in the mesopause layer, especially near the summer pole. In our time dependent calculation, waves with approximately 4-day period are generated in the m = 1 component, superimposing with the 1-day period tides. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP CHAN, KL (reprint author), APPL RES CORP,LANDOVER,MD 20785, USA. OI Chan, Kwing/0000-0002-6428-1812 NR 45 TC 20 Z9 20 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 AUG PY 1994 VL 56 IS 10 BP 1399 EP 1419 DI 10.1016/0021-9169(94)90077-9 PG 21 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NT881 UT WOS:A1994NT88100017 ER PT J AU PEARLMAN, HG RONNEY, PD AF PEARLMAN, HG RONNEY, PD TI SELF-ORGANIZED SPIRAL AND CIRCULAR WAVES IN PREMIXED GAS FLAMES SO JOURNAL OF CHEMICAL PHYSICS LA English DT Note ID PULSATING FLAME; PROPAGATION; FRONT AB A diffusive-thermal high Lewis number (Le) gas-phase oscillator has been observed in premixed flames using a lean mixture of butane and oxygen diluted with helium (Le approximate to 3.0). This reactive-diffusive system exhibits both propagating radial pulsations and rotating spiral waves perhaps analogous to those observed in other excitable media such as the Belousov-Zhabotinsky reaction. C1 UNIV SO CALIF, LOS ANGELES, CA 90089 USA. RP PEARLMAN, HG (reprint author), NASA, LEWIS RES CTR, NRC RES ASSOCIATE, CLEVELAND, OH 44135 USA. RI Ronney, Paul/B-4007-2009 OI Ronney, Paul/0000-0002-2779-6438 NR 12 TC 24 Z9 24 U1 0 U2 3 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 AUG 1 PY 1994 VL 101 IS 3 BP 2632 EP 2633 DI 10.1063/1.467636 PG 2 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NY002 UT WOS:A1994NY00200093 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H AF BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H TI A REDETERMINATION OF THE DISSOCIATION-ENERGY OF MGO+ SO JOURNAL OF CHEMICAL PHYSICS LA English DT Note ID ABINITIO CALCULATIONS; ELECTRON CORRELATION; BASIS-SETS; ATOMS RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 21 TC 12 Z9 12 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 AUG 1 PY 1994 VL 101 IS 3 BP 2644 EP 2645 DI 10.1063/1.467640 PG 2 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NY002 UT WOS:A1994NY00200097 ER PT J AU DANABASOGLU, G BIRINGEN, S STREETT, CL AF DANABASOGLU, G BIRINGEN, S STREETT, CL TI APPLICATION OF THE SPECTRAL MULTIDOMAIN METHOD TO THE NAVIER-STOKES EQUATIONS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID FLOW AB An application of the spectral multidomain method to the two-dimensional, time-dependent, incompressible Navier-Stokes equations is presented. The governing equations are discretized on a nonstaggered, stretched mesh with a mixed finite difference/Chebyshev method and are integrated by a time-splitting procedure. The accuracy of the multidomain method is demonstrated for two different channel flow configurations, one with a backward-facing step and the other with a rectangular step.The method is then applied to the investigation of the effects of an isolated, two-dimensional roughness element on the spatial development of instability waves in boundary layers. (C) 1994 Academic Press, Inc. C1 NATL CTR ATMOSPHER RES,DEPT AEROSP ENGN SCI,BOULDER,CO 80307. NASA,LANGLEY RES CTR,THEORET AERODYNAM BRANCH,HAMPTON,VA 23665. NR 13 TC 7 Z9 7 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1994 VL 113 IS 2 BP 155 EP 164 DI 10.1006/jcph.1994.1127 PG 10 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA NW811 UT WOS:A1994NW81100001 ER PT J AU CHAN, KL MAYR, HG MENGEL, JG HARRIS, I AF CHAN, KL MAYR, HG MENGEL, JG HARRIS, I TI A STRATIFIED SPECTRAL MODEL FOR STABLE AND CONVECTIVE ATMOSPHERES SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID TURBULENT COMPRESSIBLE CONVECTION; SEMI-IMPLICIT METHOD; FREQUENCY SPLITTINGS; DEEP ATMOSPHERE AB In our solar system, convective atmospheres are as common as those that are stable, and convective and stable regions sometimes coexist in the same atmosphere. There is a need to develop circulation models that can handle convection and stable-layer flows simultaneously and efficiently. This paper represents an approach to the construction of such a model. Taking advantages of the simplicity of implementing implicit time stepping in spectral models, we solve a non-hydrostatic, fully compressible version of the hydrodynamic equations without the time step restrictions imposed by acoustic and gravity waves. To simplify the nonlinear terms and to conserve the total mass and total angular momentum to round-off accuracy, we introduce a ''stratified'' approximation which limits the nonlinearity of the equations to quadratic. The linear terms remain intact so that all the linear waves are preserved. The set of assumptions made by the ''stratified'' approximation is a subset of those of the anelastic approximation. It offers more generality and accuracy while the computational overhead is relatively low. Tests are presented to illustrate the capabilities and advantages of the present model. (C) 1994 Academic Press, Inc. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP APPL RES CORP, LANDOVER, MD 20785 USA. OI Chan, Kwing/0000-0002-6428-1812 NR 49 TC 34 Z9 34 U1 0 U2 0 PU ACADEMIC PRESS INC ELSEVIER SCIENCE PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA SN 0021-9991 EI 1090-2716 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1994 VL 113 IS 2 BP 165 EP 176 DI 10.1006/jcph.1994.1128 PG 12 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA NW811 UT WOS:A1994NW81100002 ER PT J AU LOH, CY LIOU, MS AF LOH, CY LIOU, MS TI A NEW LAGRANGIAN METHOD FOR 3-DIMENSIONAL STEADY SUPERSONIC FLOWS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID DIFFERENCE APPROXIMATIONS; CONSERVATION-LAWS; COMPUTATION; RESOLUTION; SCHEMES; SHOCKS AB In this paper, the new Lagrangian method introduced by Loh and Hui is extended for 3D steady supersonic flow computation. We present the derivation of the conservation form and the solution of the local Riemann solver using the Godunov and the high resolution TVD schemes. The new approach is accurate and robust, capable of handling complicated geometry and interactions between discontinuous waves. As shown in the test problems, the current Lagrangian method retains all the advantages claimed in the 2D method, e.g., crisp resolution of a slip-surface (contact discontinuity) and automatic grid generation. In this paper, we also suggest a novel 3D Riemann problem in which interesting and intricate flow features are present. (C) 1994 Academic Press, Inc. RP LOH, CY (reprint author), NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135, USA. NR 21 TC 16 Z9 18 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 AUG PY 1994 VL 113 IS 2 BP 224 EP 248 DI 10.1006/jcph.1994.1132 PG 25 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA NW811 UT WOS:A1994NW81100006 ER PT J AU KORIVI, VM TAYLOR, AC NEWMAN, PA HOU, GW JONES, HE AF KORIVI, VM TAYLOR, AC NEWMAN, PA HOU, GW JONES, HE TI AN APPROXIMATELY FACTORED INCREMENTAL STRATEGY FOR CALCULATING CONSISTENT DISCRETE AERODYNAMIC SENSITIVITY DERIVATIVES SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID NAVIER-STOKES EQUATIONS; EULER EQUATIONS; OPTIMIZATION; DESIGN AB In this study involving advanced fluid flow codes, an incremental iterative formulation (also known as the ''delta'' or ''correction'' form), together with the well-known spatially split approximate factorization algorithm, is presented for solving the very large sparse systems of linear equations which are associated with aerodynamic sensitivity analysis. For smaller 2D problems a direct method can be applied to solve these linear equations in either the standard or the incremental form, in which case the two are equivalent. Iterative methods are needed for larger 2D and future 3D applications, however, because direct methods require much more computer memory than is currently available. Iterative methods for solving these equations in the standard form are generally unsatisfactory due to a lack of diagonal dominance and perhaps ill-conditioning of the coefficient matrix; this problem can be overcome when these equations are cast in the incremental form. These and other benefits are discussed herein. The methodology is successfully implemented and tested in 2D using an upwind, cell-centered, finite volume formulation applied to the thin-layer Navier-Stokes equations. Results are presented for two sample airfoil problems: (1) subsonic low Reynolds number laminar flow; and (2) transonic high Reynolds number turbulent flow. (C) 1994 Academic Press, Inc. C1 NASA,LANGLEY RES CTR,COMPUTAT SCI BRANCH,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,COMPUTAT SCI BRANCH,USA,AVIAT & TROOP COMMAND,HAMPTON,VA 23665. RP KORIVI, VM (reprint author), OLD DOMINION UNIV,DEPT MECH ENGN,NORFOLK,VA 23529, USA. NR 64 TC 15 Z9 16 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 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD AUG PY 1994 VL 113 IS 2 BP 336 EP 346 DI 10.1006/jcph.1994.1140 PG 11 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA NW811 UT WOS:A1994NW81100014 ER PT J AU KASPARIAN, V BATUR, C DUVAL, WMB ROSENTHAL, BN SINGH, NB AF KASPARIAN, V BATUR, C DUVAL, WMB ROSENTHAL, BN SINGH, NB TI APPLICATION OF STEREO IMAGING FOR RECOGNITION OF CRYSTAL-SURFACE SHAPES SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID GROWTH AB The shape of an interface while a crystal is growing inside a crystal growth furnace is an important measurement to assess the crystal quality on-line. If the crystal surface can be visualized by video or X-ray imaging, the interface shape can be determined by the stereo image processing techniques. This paper presents a methodology to determine the shape of the solid-melt interface by stereo based imaging techniques whiles the crystal is growing inside a transparent furnace. The methodology generates a qualitative shape information provided that a good pair of stereo images of the interface can be captured. For a quantitative shape description, i.e., for the determination of interface points with respect to a fixed coordinate frame, both cameras must be calibrated. This paper illustrates the methodology for qualitative shape determination of lead bromide crystal interface. C1 WESTINGHOUSE ELECT CORP,CTR SCI & TECHNOL,PITTSBURGH,PA 15235. UNIV AKRON,DEPT MECH ENGN,AKRON,OH 44325. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 14 TC 4 Z9 5 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 AUG PY 1994 VL 141 IS 3-4 BP 455 EP 464 DI 10.1016/0022-0248(94)90252-6 PG 10 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA PD996 UT WOS:A1994PD99600021 ER PT J AU MONHEIT, MA JOHNSTON, JC AF MONHEIT, MA JOHNSTON, JC TI SPATIAL ATTENTION TO ARRAYS OF MULTIDIMENSIONAL OBJECTS SO JOURNAL OF EXPERIMENTAL PSYCHOLOGY-HUMAN PERCEPTION AND PERFORMANCE LA English DT Article; Proceedings Paper CT 2nd Annual Conference on Recent Advances in the Analysis of Attention CY JUN, 1991 CL UNIV CALIF DAVIS, DAVIS, CA HO UNIV CALIF DAVIS ID FEATURE-INTEGRATION; VISUAL-ATTENTION; MEMORY; SEARCH; PERCEPTION; CLASSIFICATION; IDENTIFICATION; INDEPENDENCE; CONJUNCTIONS; INFORMATION AB Encoding briefly displayed arrays of multidimensional objects appears to require selective attention, but this hypothesis is challenged by M. J. Nissen's (1985) finding that properties of an object are reported independently. Selective attention to some objects but not others should produce positive dependence. Theoretical analysis shows that deviations from independence would have been difficult to observe in Nissen's data because of high guessing rates and small sample sizes. Four new experiments showing strong positive dependence in property reports are described. Deviations from independence were highly significant for most Ss. Quantitative modeling shows that selective attention to subsets of objects would produce about the amount of dependence obtained. Rather than challenging attention theories, the amount of dependence in encoding multidimensional objects is consistent with selective attention to either objects or locations. C1 NASA,AMES RES CTR,MAILSTOP 262-2,MOFFETT FIELD,CA 94035. STANFORD UNIV,DEPT PSYCHOL,STANFORD,CA 94305. NR 55 TC 21 Z9 21 U1 1 U2 1 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 AUG PY 1994 VL 20 IS 4 BP 691 EP 708 DI 10.1037/0096-1523.20.4.691 PG 18 WC Psychology; Psychology, Experimental SC Psychology GA NX812 UT WOS:A1994NX81200001 PM 8083629 ER PT J AU MCDONALD, FB BARNES, A BURLAGA, LF GAZIS, P MIHALOV, J SELESNICK, RS AF MCDONALD, FB BARNES, A BURLAGA, LF GAZIS, P MIHALOV, J SELESNICK, RS TI EFFECTS OF THE INTENSE SOLAR-ACTIVITY OF MARCH JUNE 1991 OBSERVED IN THE OUTER HELIOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID COSMIC-RAY MODULATION; MERGED INTERACTION REGIONS; RADIO-EMISSION; ACCELERATION; SHOCK; PROPAGATION; VOYAGER-2; DECREASES; DRIFTS AB The properties of the large-scale global merged interaction region (GMIR) generated by the intense solar events of March and June 1991 are studied using the available solar wind, interplanetary magnetic field, and energetic particle data from the observing network of pioneer 10 and Voyagers 1 and 2 in the outer heliosphere. At heliocentric distances extending to 55 AU the delayed effects of this enhanced solar activity are observed in the form of large increases in the solar wind velocity and interplanetary magnetic field and significant decreases in the galactic cosmic ray intensity. For low-energy ions (5-MeV protons) there was a single long-lived event extending over a period of some 6 months. Near the strongest interplanetary disturbances the H and He spectra are best represented by similar exponentials in momentum/nucleon (i.e., particle velocity at these energies). Over the rest of the event the characteristic momentum for He, (P0)H, is generally approximately 0.66 for hydrogen. These spectra and the consistently low H/He ratio (25.3) at 2 MeV/nucleon closely resemble that observed in corrotating interaction regions events. Despite the strong north/south asymmetry in the solar activity, the interplanetary disturbances produced the same net decrease in the galactic cosmic ray intensity of ions >70 MeV at the three widely separated spacecraft when the effects of the long-term recovery are taken into account. A comparison of the relative intensity of MeV ions at these three spacecraft suggest that the. most intense solar events occurred on the back side of the Sun in time periods adjacent to the March and June episodes of solar activity. It is argued that this GMIR as a system is responsible for the low-frequency radio emission observed by the Voyager Plasma Wave experiment some 1.46 years after the onset of the March 1991 activity. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. SAN JOSE STATE UNIV FDN,NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. SAN JOSE STATE UNIV,NASA,AMES RES CTR,MOFFETT FIELD,CA. CALTECH,PASADENA,CA 91125. RP MCDONALD, FB (reprint author), UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLLEGE PK,MD 20742, USA. NR 30 TC 35 Z9 35 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1994 VL 99 IS A8 BP 14705 EP 14715 DI 10.1029/94JA01004 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA015 UT WOS:A1994PA01500001 ER PT J AU MAUK, BH KRIMIGIS, SM ACUNA, MH AF MAUK, BH KRIMIGIS, SM ACUNA, MH TI NEPTUNE INNER MAGNETOSPHERE AND AURORA - ENERGETIC PARTICLE CONSTRAINTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD; HOT PLASMA; VOYAGER-2 AB A dramatic and peculiar dropout of >500-keV ions (but not electrons) was observed within Neptune's inner magnetosphere near 2 R(N) as the Voyager 2 spacecraft approached the planet. Unlike a number of other energetic particle features this feature could not be accounted for by known material bodies in the context of the most utilized magnetic field models (neither the offset tilted dipole models nor the spherical harmonic model ''O8''). However, the configuration of Neptune's inner magnetosphere is highly uncertain. By applying a novel technique, utilizing energetic particle measurements, to constrain the magnetic field configuration of the inner regions, we show that appeals to unobserved materials within Neptune's system are unnecessary, and that the ion dropout feature was, in all likelihood, the result of ion interactions with the maximum L excursions of the ring 1989N1R. The constraints also favor the use of the M2 magnetic field model (Selesnick, 1992) over previous models. An electron feature was probably absent because the electron interactions with the ring occurred substantially before the ion interactions (about 2 hours for the electrons versus a few minutes for the ions). Pitch-angle scattering apparently eliminated the electron signature. Minimum scattering rates determined based on this premise yield enough electron precipitation power to explain the brightest component of Neptune's aurora. We propose that this bright component is analogous to the Earth's diffuse aurora. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP MAUK, BH (reprint author), JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20723, USA. RI Mauk, Barry/E-8420-2017 OI Mauk, Barry/0000-0001-9789-3797 NR 18 TC 7 Z9 7 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 JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1994 VL 99 IS A8 BP 14781 EP 14788 DI 10.1029/94JA00735 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA015 UT WOS:A1994PA01500010 ER PT J AU WAITE, JH BAGENAL, F SEWARD, F NA, C GLADSTONE, GR CRAVENS, TE HURLEY, KC CLARKE, JT ELSNER, R STERN, SA AF WAITE, JH BAGENAL, F SEWARD, F NA, C GLADSTONE, GR CRAVENS, TE HURLEY, KC CLARKE, JT ELSNER, R STERN, SA TI ROSAT OBSERVATIONS OF THE JUPITER AURORA SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID HUBBLE SPACE TELESCOPE; JOVIAN AURORA; POLAR AURORA; X-RAYS; PRECIPITATION; ELECTRON; ENCOUNTER; SPECTRUM; VOYAGER; IONS AB Rontgen satellite (ROSAT) high-resolution imager (HRI) and position sensitive proportional counter (PSPC) observations of jupiter obtained in April 1991 and May 1992 reveal soft x ray emissions apparently associated with jupiter's aurora and similar to X ray emissions observed earlier by the Einstein Observatory. The HRI images show emission mainly from Jupiter's northern hemisphere at all Jovian longitudes observed, and there is some indication of a longitudinal modulation of the emission in phase with the well-known ultraviolet modulation of the northern aurora. The PSPC data reveal a very soft spectrum. Comparison of the observed spectrum with models for both electron bremsstrahlung radiation and line emission from S and O ions indicates that the line spectrum gives a much better statistical fit to the observed spectrum. The X ray observations presented here therefore support the hypothesis that ion precipitation is the most likely cause of the Jovian X ray emissions, a result first suggested by the Einstein results [Metzger et al., 1983]. C1 UNIV KANSAS,DEPT PHYS,LAWRENCE,KS 66045. HARVARD UNIV,ASTRON OBSERV,CAMBRIDGE,MA 02138. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV COLORADO,DEPT ASTROPHYS PLANETARY & ATMOSPHER SCI,BOULDER,CO 80309. UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. RP WAITE, JH (reprint author), SW RES INST,DEPT SPACE SCI,SPACE SCI LAB,SAN ANTONIO,TX 78228, USA. RI Clarke, John/C-8644-2013 NR 24 TC 75 Z9 75 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 JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1994 VL 99 IS A8 BP 14799 EP 14809 DI 10.1029/94JA01005 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA015 UT WOS:A1994PA01500012 ER PT J AU KLIMAS, AJ BAKER, DN VASSILIADIS, D ROBERTS, DA AF KLIMAS, AJ BAKER, DN VASSILIADIS, D ROBERTS, DA TI SUBSTORM RECURRENCE DURING STEADY AND VARIABLE SOLAR-WIND DRIVING - EVIDENCE FOR A NORMAL-MODE IN THE UNLOADING DYNAMICS OF THE MAGNETOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID AL TIME-SERIES; GEOMAGNETIC-ACTIVITY; STOCHASTIC-SYSTEMS; AE; CRITICALITY; CHAOS AB Farrugia et al. (1993) have recently studied substorm activity driven by the passage of an interplanetary magnetic cloud during which the interplanetary magnetic field turned southward for approximately 18 hours. It was shown that both the epsilon and the VB(s) parameters varied slowly on the timescale of a substorm but changed considerably over the interval as a whole. The substorm occurrence rate did not reflect the variation in magnetospheric energy loading rate as measured by these parameters but, rather, remained roughly constant with a 50-min average period. Klimas et al. (1992) showed that the Faraday loop analogue model of geomagnetic activity predicts this single unloading rate under various constant loading rates. However, various model parameters were adjusted to yield a 1-hour unloading period in agreement with the Bargatze et al. (1985) linear prediction filters and in approximate agreement with the Farrugia et al. (1993) results. It has since been found necessary to add a slow relaxation mechanism to the Faraday loop model to allow for its approach to a ground state during long periods of inactivity. It is proposed that the relaxation mechanism is provided by slow convection of magnetic flux out of the magnetotail to the dayside magnetosphere. In addition, a rudimentary representation of magnetotail-ionosphere coupling has been added to enable comparison of model output to measured AL. The present study is of the modified Faraday loop model response to solar wind input from the Bargatze et al. data set with comparison of its output to concurrent AL. This study has removed the degree of freedom in parameter choice that had earlier allowed adjustments toward the 1-hour unloading period and has, instead, yielded the 1-hour unloading period under various constant loading rates. It is demonstrated that the second peak of the bimodal Bargatze et al. linear prediction filters at almost-equal-to 1-hour lag and the approximately constant substorm recurrence rate observed by Farrugia et al. can be interpreted as both being due to the existence of a normal unloading recurrence period in the dynamics of the magnetosphere. RP KLIMAS, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012 NR 35 TC 52 Z9 52 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1994 VL 99 IS A8 BP 14855 EP 14861 DI 10.1029/94JA01240 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA015 UT WOS:A1994PA01500016 ER PT J AU BIRN, J SCHINDLER, K JANICKE, L HESSE, M AF BIRN, J SCHINDLER, K JANICKE, L HESSE, M TI MAGNETOTAIL DYNAMICS UNDER ISOBARIC CONSTRAINTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CENTRAL PLASMA SHEET; FIELD-ALIGNED CURRENTS; SUBSTORM CURRENT WEDGE; MAGNETOSPHERIC SUBSTORMS; GROWTH-PHASE; EARTHS MAGNETOTAIL; CURRENT DIVERSION; GEOMAGNETIC TAIL; MAGNETIC-FIELD; NEUTRAL SHEET AB Using linear theory and nonlinear MHD simulations, we investigate the resistive and ideal MHD stability of two-dimensional plasma configurations under the isobaric constraint dP/dt = 0, which in ideal MHD is equivalent to conserving the pressure function P = P(A), where A denotes the magnetic flux. This constraint is satisfied for incompressible modes, such as Alfven waves, and for systems undergoing energy losses. The linear stability analysis leads to a Schrodinger equation, which can be investigated by standard quantum mechanics procedures. We present an application to a typical stretched magnetotail configuration. For a one-dimensional sheet equilibrium characteristic properties of tearing instability are rediscovered. However, the maximum growth rate scales with the 1/7 power of the resistivity, which implies much faster growth than for the standard tearing mode (assuming that the resistivity is small). The same basic eigen-mode is found also for weakly two-dimensional equilibria, even in the ideal MHD limit. In this case the growth rate scales with the 1/4 power of the normal magnetic field. The results of the linear stability analysis are confirmed qualitatively by nonlinear dynamic MHD simulations. These results suggest the interesting possibility that substorm onset, or the thinning in the late growth phase, is caused by the release of a thermodynamic constraint without the (immediate) necessity of releasing the ideal MHD constraint. In the nonlinear regime the resistive and ideal developments differ in that the ideal mode does not lead to neutral line formation without the further release of the ideal MHD constraint; instead a thin current sheet forms. The isobaric constraint is critically discussed. Under perhaps more realistic adiabatic conditions the ideal mode appears to be stable but could be driven by external perturbations and thus generate the thin current sheet in the late growth phase, before a nonideal instability sets in. C1 NASA,GODDARD SPACE FLIGHT CTR,ELECTRODYNAM BRANCH,GREENBELT,MD 20771. RUHR UNIV BOCHUM,D-44780 BOCHUM,GERMANY. RP BIRN, J (reprint author), LOS ALAMOS NATL LAB,SPACE & ATMOSPHER SCI GRP,MS D466,LOS ALAMOS,NM 87545, USA. RI Hesse, Michael/D-2031-2012 NR 48 TC 11 Z9 11 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 AUG 1 PY 1994 VL 99 IS A8 BP 14863 EP 14875 DI 10.1029/94JA00862 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA015 UT WOS:A1994PA01500017 ER PT J AU FARRUGIA, CJ FREEMAN, MP AF FARRUGIA, CJ FREEMAN, MP TI THE EARTHS MAGNETOSPHERE UNDER CONTINUED FORCING - SUBSTORM ACTIVITY DURING THE PASSAGE OF AN INTERPLANETARY CLOUD - REPLY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Note ID GEOMAGNETIC-ACTIVITY C1 BRITISH ANTARCTIC SURVEY,CAMBRIDGE CB3 0ET,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP FARRUGIA, CJ (reprint author), UNIV MALTA,DEPT SCI & TECHNOL EDUC,MSIDA,MALTA. NR 8 TC 10 Z9 10 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1994 VL 99 IS A8 BP 14941 EP 14945 DI 10.1029/94JA00364 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA015 UT WOS:A1994PA01500023 ER PT J AU COLE, KD AF COLE, KD TI ORIGIN OF FLUX ROPES IN VENUS IONOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ELECTRIC CURRENTS; PLANETARY IONOSPHERES; MAGNETIC-FIELDS; MODEL; THERMOSPHERE AB The joule dissipation inside flux ropes in Venus' ionosphere is so great that they must be formed near, and maintained at, the place where they are observed. Thus ropes are not formed by a Kelvin-Helmholtz instability of the ionopause. The hypothesis that ropes may be formed by the dynamo action of internal gravity waves in Venus' thermosphere (Luhmann and Elphic, 1985; Cole, 1993) is strengthened by discussion of a magnetic evolution equation which includes neutral air motion. However, the dynamo process would work only at altitudes at which v(in) greater-than-or-equal-to omega(i). At altitudes or parts of a rope where v(in) much less than omega(i), the process does not work. A solar wind dynamo is therefore examined to account for the ropes. Thereby a major new heat source for ions of the Venus ionosphere associated with the ropes is uncovered. RP COLE, KD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. NR 22 TC 7 Z9 7 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 AUG 1 PY 1994 VL 99 IS A8 BP 14951 EP 14958 DI 10.1029/93JA03528 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA015 UT WOS:A1994PA01500025 ER PT J AU HORWITZ, JL HO, CW SCARBRO, HD WILSON, GR MOORE, TE AF HORWITZ, JL HO, CW SCARBRO, HD WILSON, GR MOORE, TE TI CENTRIFUGAL ACCELERATION OF THE POLAR WIND SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ION OUTFLOWS; PLASMA OUTFLOW; KINETIC-MODEL; O+ IONS; CAP; IONOSPHERE; MAGNETOSPHERE; REGION; SPECTROMETER; CONVECTION AB The effect of parallel ion acceleration associated with convection was first applied to energization of test particle polar ions by Cladis (1986). However, this effect is typically neglected in ''self-consistent'' models of polar plasma outflow, apart from the fluid simulation by Swift [1990]. Here we include approximations for this acceleration, which we broadly characterize as centrifugal in nature, in our time-dependent, semikinetic model of polar plasma outflow and describe the effects on the bulk parameter profiles and distribution functions of H+ and O+. For meridional convection across the pole the approximate parallel force along a polar magnetic field line may be written as F(cent,pole) = 1.5m(E(i)/B(i))2(r2/r(i)3) where m is ion mass, r is geocentric distance; and E(i), B(i) and r(i) refer to the electric and magnetic field magnitudes and geocentric distance at the ionosphere, respectively. For purely longitidinal convection along a constant L shell the parallel force is F(cent,long) = F(cent,pole) [1-(r/(r(i)L)]3/2/[1-3r/(4r(i)L)]5/2. For high latitudes the difference between these two cases is relatively unimportant below approximately 5 R(E). We find that the steady state O+ bulk velocities and parallel temperatures strongly increase and decrease, respectively, with convection strength. In particular, the bulk velocities increase from near 0 km s-1 at 4000 km altitude to approximately 10 km s-1 at 5 R(E) geocentric distance for a 50-mV/m ionospheric convection electric field. However, the centrifugal effect on the steady O+ density profiles depends on the exobase ion and electron temperatures: for low-base temperatures (T(i) = T(e) = 3000 K) the O+ density at high altitudes increases greatly with convection, while for higher base temperatures (T(i) = 5000 K, T(e) = 9000 K), the high-altitude O+ density decreases somewhat as convection is enhanced. The centrifugal force further has a pronounced effect on the escaping O+ flux, especially for cool exobase conditions; as referenced to the 4000-km altitude, the steady state O+ flux increases from 10(5) ions cm-2 s-1 when the ionospheric convection field E(i) = 0 mV/m to approximately 10(7) ions cm-2 s-1 when E(i) = 100 mV/m. The centrifugal effect also decreases the time scale for approach to steady-state. For example, in the plasma expansion for T(i) = T(e) = 3000 K, the O+ density at 7 R(E) reaches only 10(-7) of its final value approximately 1.5 hours after expansion onset for E(i) = 0. For meridional convection driven by E(i) = 50 mV/m, the density at the same time after initial injection is 30-50% of its asymptotic level. The centrifugal acceleration described here is a possible explanation for the large (up to approximately 10 km s-1 or more) O+ outflow velocities observed in the midaltitude polar magnetosphere with the Dynamics Explorer 1 and Akebono spacecraft. C1 UNIV ALABAMA,CTR SPACE PLASMA & AERONOM RES,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP HORWITZ, JL (reprint author), UNIV ALABAMA,DEPT PHYS,ENGN BLDG 163-M,HUNTSVILLE,AL 35899, USA. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 37 TC 70 Z9 70 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD AUG 1 PY 1994 VL 99 IS A8 BP 15051 EP 15064 DI 10.1029/94JA00924 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA015 UT WOS:A1994PA01500033 ER PT J AU KAMOTANI, Y WENG, FB OSTRACH, S PLATT, J AF KAMOTANI, Y WENG, FB OSTRACH, S PLATT, J TI OSCILLATORY NATURAL-CONVECTION OF A LIQUID-METAL IN CIRCULAR-CYLINDERS SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Article DE LIQUID METALS; NATURAL CONVECTION; TRANSIENT AND UNSTEADY HEAT TRANSFER ID VERTICAL CYLINDER AB An experimental study is made of natural convection oscillations in gallium melts enclosed by right circular cylinders with differentially heated end walls. Cases heated from below are examined for angles of inclination (phi) ranging from 0 deg (vertical) to 75 deg with aspect ratios Ar (height/diameter) of 2, 3, and 4. Temperature measurements are made along the circumference of the cylinder to detect the oscillations, from which the oscillatory flow structures are inferred. The critical Rayleigh numbers and oscillation frequencies are determined. For Ar = 3 and phi = 0 deg, 30 deg the supercritical flow structures are discussed in detail. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP KAMOTANI, Y (reprint author), CASE WESTERN RESERVE UNIV,DEPT MECH & AEROSP ENGN,CLEVELAND,OH 44106, USA. NR 13 TC 14 Z9 14 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-1481 J9 J HEAT TRANS-T ASME JI J. Heat Transf.-Trans. ASME PD AUG PY 1994 VL 116 IS 3 BP 627 EP 632 DI 10.1115/1.2910915 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PD421 UT WOS:A1994PD42100013 ER PT J AU SIEGEL, R SPUCKLER, CM AF SIEGEL, R SPUCKLER, CM TI EFFECTS OF REFRACTIVE-INDEX AND DIFFUSE OR SPECULAR BOUNDARIES ON A RADIATING ISOTHERMAL LAYER SO JOURNAL OF HEAT TRANSFER-TRANSACTIONS OF THE ASME LA English DT Note DE RADIATION RP SIEGEL, R (reprint author), NASA,LEWIS RES CTR,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 3 TC 17 Z9 17 U1 0 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0022-1481 J9 J HEAT TRANS-T ASME JI J. Heat Transf.-Trans. ASME PD AUG PY 1994 VL 116 IS 3 BP 787 EP 790 DI 10.1115/1.2910943 PG 4 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA PD421 UT WOS:A1994PD42100041 ER PT J AU VIKRAM, CS WITHEROW, WK TROLINGER, JD AF VIKRAM, CS WITHEROW, WK TROLINGER, JD TI FRINGE CONTRAST AND PHASE EFFECTS IN MULTICOLOR HOLOGRAPHY SO JOURNAL OF MODERN OPTICS LA English DT Article ID INTERFEROMETRY; NEEDS AB The role of phase difference among component holograms in multicolour holography is described from the hologram fringe contrast point of view. The fraction of the hologram below a certain contrast factor against different phases and hologram types is considered. The holographic techniques considered are two- and three-colour holography with irrationally related wavelengths, and two-colour holography with frequency-doubled lasers. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. METROLASER,IRVINE,CA 92714. RP VIKRAM, CS (reprint author), UNIV ALABAMA,CTR APPL OPT,HUNTSVILLE,AL 35899, USA. NR 10 TC 3 Z9 3 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0950-0340 J9 J MOD OPTIC JI J. Mod. Opt. PD AUG PY 1994 VL 41 IS 8 BP 1531 EP 1536 DI 10.1080/09500349414552401 PG 6 WC Optics SC Optics GA PH495 UT WOS:A1994PH49500002 ER PT J AU GREINER, E PERIGAUD, C AF GREINER, E PERIGAUD, C TI ASSIMILATION OF GEOSAT ALTIMETRIC DATA IN A NONLINEAR REDUCED-GRAVITY MODEL OF THE INDIAN-OCEAN .1. ADJOINT APPROACH AND MODEL DATA CONSISTENCY SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID SHALLOW-WATER SIMULATIONS; TROPICAL PACIFIC-OCEAN; SEA-LEVEL VARIATIONS; XBT DATA; CIRCULATION; SENSITIVITY; ATLANTIC AB Geosat sea-level variations are assimilated into a nonlinear shallow-water model of the Indian Ocean. After spinup, the model forced by observed winds over 1985-1988 provides a first guess for initial conditions on November 1986 and a mean thermocline depth used as a reference surface for altimetric observations. Data are assimilated during one year and north of 20-degrees-S. The model-data misfit is minimized using the adjoint model with respect to the initial conditions and the reference surface. The assimilation algorithm converges fast and steadily. The monthly rms difference between model and data is reduced from 21 to 16 m. The optimal thermocline surface is significantly affected by assimilation. Large changes occur along the paths of the through flow and South Equatorial Current. It is found that the optimal mean state is valid only for the period of assimilation. It degrades the agreement between observations and simulations for the following year because of the large interannual event that took place over 1986-1988. With an assumed 7-cm observation error, model and data are overall consistent. But the model is fundamentally inconsistent with data in the Bay of Bengal or in the Indonesian Through flow region. Examples of erroneous conclusions about model-data consistency are given when data are assimilated with faked assumptions on the observation error structure. C1 JET PROP LAB,MAIL STOP 300-323,4800 OAK GROVE DR,PASADENA,CA 91109. UNIV PARIS 06,LODYC,F-75230 PARIS 05,FRANCE. NR 39 TC 11 Z9 12 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD AUG PY 1994 VL 24 IS 8 BP 1783 EP 1804 DI 10.1175/1520-0485(1994)024<1783:AOGADI>2.0.CO;2 PG 22 WC Oceanography SC Oceanography GA NZ735 UT WOS:A1994NZ73500008 ER PT J AU CHEN, TC PFAENDTNER, J WENG, SP AF CHEN, TC PFAENDTNER, J WENG, SP TI ASPECTS OF THE HYDROLOGICAL CYCLE OF THE OCEAN-ATMOSPHERE SYSTEM SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Note ID FRESH-WATER; TRANSPORTS AB The balance equations for atmospheric water vapor and freshwater in the oceans are used to illustrate that evaporation and precipitation represent the major linkage between the atmospheric and oceanic branches of the global hydrological cycle. Attempts are also made to establish the hydrological cycle of the coupled ocean-atmosphere system using water vapor flux divergence, PreciPitation, and interoceanic freshwater transport estimates from previous studies as well as computational results with more recent data. This hydrological cycle works as follows: the atmospheric water vapor converged to the Pacific results in an excess of precipitation and a freshwater transport across the Bering Strait and the Arctic Sea to the Atlantic. The atmospheric water vapor is then diverged out of the latter ocean due to an excess of evaporation there. C1 NASA,GODDARD SPACE FLIGHT CTR,DATA ASSIMILAT OFF,GREENBELT,MD 20771. RP CHEN, TC (reprint author), IOWA STATE UNIV SCI & TECHNOL,DEPT GEOL & ATMOSPHER SCI,ATMOSPHER SCI PROGRAM,AMES,IA 50011, USA. NR 16 TC 21 Z9 21 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-3670 J9 J PHYS OCEANOGR JI J. Phys. Oceanogr. PD AUG PY 1994 VL 24 IS 8 BP 1827 EP 1833 DI 10.1175/1520-0485(1994)024<1827:AOTHCO>2.0.CO;2 PG 7 WC Oceanography SC Oceanography GA NZ735 UT WOS:A1994NZ73500011 ER PT J AU ASAKIMORI, K BURNETT, TH CHERRY, ML CHRISTL, MJ DAKE, S DERRICKSON, JH FOUNTAIN, WF FUKI, M GREGORY, JC HAYASHI, T HOLYNSKI, R IWAI, J IYONO, A JONES, WV LORD, JJ MIYAMURA, O ODA, H OGATA, T OLSON, ED PARNELL, TA ROBERTS, FE STRAUSZ, SC TAKAHASHI, Y TOMINAGA, T WATTS, JW WEFEL, JP WILBER, M WILCZYNSKA, B WILCZYNSKI, H WILKES, RJ WOLTER, W ZAGER, EL AF ASAKIMORI, K BURNETT, TH CHERRY, ML CHRISTL, MJ DAKE, S DERRICKSON, JH FOUNTAIN, WF FUKI, M GREGORY, JC HAYASHI, T HOLYNSKI, R IWAI, J IYONO, A JONES, WV LORD, JJ MIYAMURA, O ODA, H OGATA, T OLSON, ED PARNELL, TA ROBERTS, FE STRAUSZ, SC TAKAHASHI, Y TOMINAGA, T WATTS, JW WEFEL, JP WILBER, M WILCZYNSKA, B WILCZYNSKI, H WILKES, RJ WOLTER, W ZAGER, EL TI MULTIPLE-PHOTON EMISSION IN HEAVY-PARTICLE DECAYS SO JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS LA English DT Article ID ENERGY AB Cosmic-ray interactions, at energies above 1 TeV/nucleon, in emulsion chambers flown on high altitude balloons have yielded two events showing apparent decays of a heavy particle into one charged particle and four photons. The photons converted into electron pairs very close to the decay vertex. Attempts to explain this decay topology with known particle decays are presented. Unless both events represent a b --> u transition, which is statistically unlikely, then other known decay modes for charmed or bottom particles do not account satisfactorily for these observations. This could possibly indicate a new decay channel. C1 UNIV ALABAMA,HUNTSVILLE,AL 35899. OKAYAMA UNIV,OKAYAMA 700,JAPAN. UNIV WASHINGTON,SEATTLE,WA 98195. LOUISIANA STATE UNIV,BATON ROUGE,LA 70803. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. KOBE UNIV,KOBE 657,JAPAN. KOCHI UNIV,KOCHI 780,JAPAN. UNIV TOKYO,INST COSM RAY RES,TOKYO 113,JAPAN. INST NUCL PHYS,HIGH ENERGY PHYS LAB,PL-63055 KRAKOW,POLAND. OKAYAMA UNIV SCI,OKAYAMA,JAPAN. HIROSHIMA UNIV,HIROSHIMA 730,JAPAN. RP ASAKIMORI, K (reprint author), KOBE WOMENS JR COLL,KOBE,JAPAN. RI Wilkes, R.Jeffrey/E-6011-2013 NR 9 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 AUG PY 1994 VL 20 IS 8 BP 1257 EP 1265 PG 9 WC Physics, Nuclear; Physics, Particles & Fields SC Physics GA PA634 UT WOS:A1994PA63400016 ER PT J AU RUSSO, EP STCYR, WW HERRINGTON, PD AF RUSSO, EP STCYR, WW HERRINGTON, PD TI THERMAL-STRESSES IN A PARTIALLY FILLED HORIZONTAL VESSEL SO JOURNAL OF PRESSURE VESSEL TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article AB Stresses produced by a thermal gradient in the wall of a partially filled horizontal cylindrical vessel are presented. Three different thermal gradients are considered: 1) a discontinuous temperature change; 2) a hyperbolic temperature change; and 3) a linear temperature change at the liquid level. Thermal shock effects are also presented. C1 NASA,TEST & ENGN DIRECTORATE,JOHN C STENNIS SPACE CTR,BAY ST LOUIS,MS 39529. RP RUSSO, EP (reprint author), UNIV NEW ORLEANS,DEPT MECH ENGN,NEW ORLEANS,LA 70148, USA. NR 11 TC 2 Z9 2 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-9930 J9 J PRESS VESS-T ASME JI J. Press. Vessel Technol.-Trans. ASME PD AUG PY 1994 VL 116 IS 3 BP 302 EP 305 DI 10.1115/1.2929592 PG 4 WC Engineering, Mechanical SC Engineering GA PE104 UT WOS:A1994PE10400010 ER PT J AU OH, JJ COHEN, EA AF OH, JJ COHEN, EA TI PRESSURE BROADENING OF CLO BY N-2 AND O-2 NEAR 204 AND 649 GHZ AND NEW FREQUENCY MEASUREMENTS BETWEEN 632 AND 725 GHZ SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID OZONE; NITROGEN; SPECTRUM; CIO AB The N-2 and O-2 pressure broadening of the ClO transitions near 204 and 649 GHz have been measured between 200 and 300 K. Oxygen broadening has been measured for the transitions near 278 GHz. The accuracy of the derived air broadening is comparable to that for the air broadening of stable species and is estimated to be within approximate to 3% over the entire temperature range. These transitions are currently being used for satellite, balloon, and ground based monitoring of atmospheric ClO, respectively. Some new frequency measurements are reported in the 632-725 GHz range. These are in good agreement with previous measurements and predictions. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 13 TC 22 Z9 22 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD AUG PY 1994 VL 52 IS 2 BP 151 EP 156 DI 10.1016/0022-4073(94)90004-3 PG 6 WC Optics; Spectroscopy SC Optics; Spectroscopy GA PF389 UT WOS:A1994PF38900004 ER PT J AU PROSSER, WH GORMAN, MR AF PROSSER, WH GORMAN, MR TI PLATE MODE VELOCITIES IN GRAPHITE/EPOXY PLATES SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Article ID WAVES AB Measurements of the velocities of the extensional and flexural plate modes were made along three directions of propagation in four graphite/epoxy composite plates. The acoustic signals were generated by simulated acoustic emission events (pencil lead breaks or Hsu-Neilsen sources) and detected by broadband ultrasonic transducers. The first arrival of the extensional plate mode, which is nondispersive at low frequencies, was measured at a number of different distances from the source along the propagation direction of interest. The velocity was determined by plotting the distance versus arrival time and computing its slope. Because of the large dispersion of the flexural mode, a Fourier phase velocity technique was used to characterize this mode. The velocity was measured up to a frequency of 160 kHz. Theoretical predictions of the velocities of these modes were also made and compared with experimental observations. classical plate theory yielded good agreement with the measured extensional velocities. For predictions of the dispersion of the flexural mode, Mindlin plate theory, which includes the effects of shear deformation and rotatory inertia was shown to give better agreement with the experimental measurements. C1 UNIV DENVER, DEPT ENGN, DENVER, CO 80208 USA. RP NASA, LANGLEY RES CTR, MS 231, HAMPTON, VA 23681 USA. NR 20 TC 29 Z9 30 U1 1 U2 4 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 AUG PY 1994 VL 96 IS 2 BP 902 EP 907 DI 10.1121/1.410265 PN 1 PG 6 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA PB503 UT WOS:A1994PB50300032 ER PT J AU RATNAKUMAR, BV WITHAM, C FULTZ, B HALPERT, G AF RATNAKUMAR, BV WITHAM, C FULTZ, B HALPERT, G TI ELECTROCHEMICAL EVALUATION OF LA-NI-SN METAL HYDRIDE ALLOYS SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Letter ID METHANOL FUEL-CELLS; ELECTRODES; CATALYSTS; PLATINUM; BATTERY AB A detailed electrochemical evaluation of Sn-modified LaNi5 was performed to evaluate its performance as a negative electrode in alkaline rechargeable cells. Substituting small amounts of Sn for Ni provides a large improvement in the initial capacity and cycle lifetime of the electrode, and also serves to improve the kinetics of hydrogen absorption-desorption processes. C1 CALTECH,DIV ENGN & APPL SCI,PASADENA,CA 91125. RP RATNAKUMAR, BV (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 16 TC 20 Z9 20 U1 0 U2 2 PU ELECTROCHEMICAL SOC INC PI PENNINGTON PA 10 SOUTH MAIN STREET, PENNINGTON, NJ 08534 SN 0013-4651 J9 J ELECTROCHEM SOC JI J. Electrochem. Soc. PD AUG PY 1994 VL 141 IS 8 BP L89 EP L91 DI 10.1149/1.2055105 PG 3 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA PA463 UT WOS:A1994PA46300001 ER PT J AU LAU, KM WU, HT AF LAU, KM WU, HT TI LARGE-SCALE DYNAMICS ASSOCIATED WITH SUPER CLOUD CLUSTER ORGANIZATION OVER THE TROPICAL WESTERN PACIFIC SO JOURNAL OF THE METEOROLOGICAL SOCIETY OF JAPAN LA English DT Article ID FREQUENCY INTRASEASONAL OSCILLATIONS; EASTERLY WAVES; ATMOSPHERE; CONVECTION; ORIGIN; DISTURBANCES; WINTER; OCEAN; CISK AB Using a nonlinear primitive equation model of the tropical atmosphere, we have studied the large scale dynamics associated with the organization of super-cloud clusters (SCC) and the effect of nonlinear mean flow interaction and lateral forcing on the evolution of SCC and the Madden and Julian Oscillation (MJO) over the tropical western Pacific. It is found that the nonlinear interaction between convection and the large scale circulation associated with the organization of SCC can excite a variety of symmetric divergent motions along the equator and rotational motions away from the equator. The former can be identified as eastward propagating moist Kelvin waves and westward propagating inertia-gravity waves and the latter as Rossby waves. The interaction between the SCC and a basic flow induced by a northern wintertime heat source distribution gives rise to quasi-stationary modes over the western Pacific which may be identified with mixed Rossby-gravity wave. Westerly vertical wind shear over the western Pacific modifies the vertical tilt of the MJO and favors its growth. During the northern winter, cold surges from the East Asian continent exert strong control on the development of SCC in the equatorial regions by inducing pressure differential across the maritime continent and the western Pacific, leading to enhancement of surface wind convergence. When the influence of the subsidence motion associated with a pre-existing SCC/MJO is weakened, the cold surge-induced pressure anomaly can lead to the development of new SCC with intermediate time scales. The time interval between intermediate SCCs is about 8-10 days which is approximately the transit time of the MJO across the span of the warm pool of the western Pacific. During the northern summer, the SCCs in the equatorial region are much less organized with mixed eastward and westward propagating signals. In the northern subtropics (15-degrees-N-20-degrees-N), westward propagating synoptic scale waves are found in regions with strong westerly shear. These waves grow by latent heating as well as by extracting wave energy from the mean westerly vertical shear in the lower troposphere. Overall, the results suggest that the organization and location of SCC and the associated multi-scale motions are strongly dependent on the evolving seasonal mean flow. C1 APPL RES CORP, LANDOVER, MD 20785 USA. RP LAU, KM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RI Lau, William /E-1510-2012 OI Lau, William /0000-0002-3587-3691 NR 17 TC 6 Z9 6 U1 0 U2 0 PU METEOROLOGICAL SOC JAPAN PI TOKYO PA C/O JAPAN METEOROLOGICAL AGENCY 1-3-4 OTE-MACHI, CHIYODA-KU, TOKYO, 100-0004, JAPAN SN 0026-1165 EI 2186-9057 J9 J METEOROL SOC JPN JI J. Meteorol. Soc. Jpn. PD AUG PY 1994 VL 72 IS 4 BP 481 EP 497 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA PM872 UT WOS:A1994PM87200001 ER PT J AU SCHNETZLER, CC DOIRON, SD WALTER, LS KRUEGER, AJ AF SCHNETZLER, CC DOIRON, SD WALTER, LS KRUEGER, AJ TI SATELLITE MEASUREMENT OF SULFUR-DIOXIDE FROM THE REDOUBT ERUPTIONS OF 1989-1990 SO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH LA English DT Article AB The mass of SO2 emitted by the 16 major explosive eruptions of Redoubt Volcano between December 1989 and April 1990 have been examined by the Total Ozone Mapping Spectrometer (TOMS) carried on the Nimbus 7 satellite. Because of low light levels during the winter months, TOMS could not detect SO2 at high northern latitudes. Thus, the major eruptions from December through February could not be monitored unless winds brought the clouds to latitudes lower than about 58 degrees N. Only two SO2 clouds were observed in the satellite data - an approximately 100-kiloton (kt) cloud on December 16 over Nevada and eastern California, and a 10-kt cloud on March 9 directly over the volcano. We speculate that the major eruption on December 15 at 1015 hour produced the 100-kt cloud seen on December 16, and the mass of SO2 injected into the atmosphere at that time was 175+/-50 kt. C1 HUGHES STX CORP,LANHAM,MD. RP SCHNETZLER, CC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EARTH SCI DIRECTORATE,GREENBELT,MD 20771, USA. NR 4 TC 14 Z9 14 U1 0 U2 3 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 AUG PY 1994 VL 62 IS 1-4 BP 353 EP 357 DI 10.1016/0377-0273(94)90041-8 PG 5 WC Geosciences, Multidisciplinary SC Geology GA PH198 UT WOS:A1994PH19800018 ER PT J AU HELMICK, LS JONES, WR AF HELMICK, LS JONES, WR TI DETERMINATION OF THE OXIDATIVE STABILITY OF PERFLUOROPOLYALKYL ETHERS AND CORRELATION WITH CHEMICAL-STRUCTURE SO LUBRICATION ENGINEERING LA English DT Article DE LUBRICATION FUNDAMENTALS; SYNTHETIC LUBRICANTS ID TEMPERATURE; DEGRADATION; OXIDE; LUBRICANTS; SURFACES; ALUMINUM; FLUIDS; MODELS; STEEL; FEF3 AB The oxidative stabilities of several perfluoropolyalkyl ethers (PFPAE) with related chemical structures have been determined by thermal gravimetric analysis and correlated with their chemical structures. These results show that oxidative stability increases as the number of difluoroformal groups decreases and as trifluoromethyl substituents are added. They are also consistent with a recently proposed intramolecular disproportionation reaction mechanism involving coordination of successive ether oxygens to a Lewis acid. Since polytetrafluoroethylene contains no oxygen, it provides an indication of the upper limit to oxidative stability of PFPAE fluids. These results also show that oxidative decomposition of PFPAE fluids requires the presence of an active metal as well as air. Consequently, it may be possible to minimize decomposition and thus improve oxidative stability by passivating reactive metal surfaces. C1 NASA,LEWIS RES CTR,LUBRICAT BRANCH,CLEVELAND,OH 44135. RP HELMICK, LS (reprint author), CEDARVILLE COLL,CEDARVILLE,OH 45314, USA. NR 29 TC 1 Z9 1 U1 0 U2 0 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD AUG PY 1994 VL 50 IS 8 BP 649 EP 655 PG 7 WC Engineering, Mechanical SC Engineering GA PA205 UT WOS:A1994PA20500006 ER PT J AU VLASSE, M PALEY, MS AF VLASSE, M PALEY, MS TI THE CRYSTAL AND MOLECULAR-STRUCTURE OF AN ASYMMETRIC DIACETYLENE MONOMER, 6-(2-METHYL-4-NITROANILINO)-2,4-HEXADIYN-1-OL SO MACROMOLECULAR CHEMISTRY AND PHYSICS LA English DT Article ID SOLID-STATE AB The crystal and molecular structure of an asymmetric diacetylene monomer has been determined from x-ray diffraction data. The crystals, obtained from an acetone/pentane solution, are orthorhombic, Fdd2 with Z = 16 in a unit cell having dimensions of a = 42,815(6) angstrom, b = 22,224(5) angstrom, c = 4,996(1) angstrom. The structure was solved by direct methods and refined by least-squares techniques to an R(F) of 6,4 % for 988 reflections and 171 variables. The diacetylene chains are disposed in the unit cell in a complex manner in order to satisfy the hydrogen-bonding, crystal packing, and symmetry requirements of the system. The solid state polymerization mechanism is discussed with respect to the geometric disposition of the diacetylene chains. These chains are far apart and incorrectly oriented with respect to each other to permit polymerization in the crystal by means of 1,4-addition, consistent with the Baughman mechanistic model. RP VLASSE, M (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 14 TC 1 Z9 1 U1 0 U2 1 PU HUTHIG & WEPF VERLAG PI BASEL PA AUF DEM WOLF 4 FX#001-41-61-317-94-11, CH-4052 BASEL, SWITZERLAND SN 1022-1352 J9 MACROMOL CHEM PHYSIC JI Macromol. Chem. Phys. PD AUG PY 1994 VL 195 IS 8 BP 2791 EP 2797 DI 10.1002/macp.1994.021950810 PG 7 WC Polymer Science SC Polymer Science GA PB010 UT WOS:A1994PB01000010 ER PT J AU BARUA, DK KUEHL, SA MILLER, RL MOORE, WS AF BARUA, DK KUEHL, SA MILLER, RL MOORE, WS TI SUSPENDED SEDIMENT DISTRIBUTION AND RESIDUAL TRANSPORT IN THE COASTAL OCEAN OFF THE GANGES-BRAHMAPUTRA RIVER MOUTH SO MARINE GEOLOGY LA English DT Article; Proceedings Paper CT Session on Tidal and Shallow-Sea Sediments - Modern Environments, held at the 29th International Geological Congress CY AUG 27-28, 1992 CL KYOTO, JAPAN ID HYDRAULIC INTERPRETATION; SIZE DISTRIBUTIONS; BENGAL; SAND; MOVEMENT; SYSTEM; SHELF; BED AB An examination of suspended sediment dispersal in the coastal ocean off the Ganges-Brahmaputra river system using shipboard and satellite data reveal distinct patterns of sediment distribution and sediment motion which help explain the dynamics of the world's largest sediment dispersal system. During the low-discharge period, suspended sediment concentration distribution is mainly a function of tidal energy and the sediments are primarily transported as a suspension population. Satellite and sea-bed data indicate that transport of river sediments is largely restricted to an area landward of about the 20-isobath during the low-discharge period. A simplistic estimate of residual transport and its separation into tidal and non-tidal components indicate that non-tidal transport contributes about 47% of the total transport and has transport directions mostly southwestward during the northeast monsoon. The tidal residual transport, which contributes about 53% of the total transport, however, does not show any particular direction for most of the stations, although some landward stations show shoreward transport. Although few water-column measurements were made during the high-discharge period, data from this and previous studies suggest that the dominant transport direction is to the southwest for most of the year. C1 COLL WILLIAM & MARY,SCH MARINE SCI,VIRGINIA INST MARINE SCI,GLOUCESTER POINT,VA 23062. NASA,EARTH OBSERVAT PROJECTS OFF,BAY ST LOUIS,MS 39529. UNIV S CAROLINA,DEPT GEOL SCI,COLUMBIA,SC 29208. RP BARUA, DK (reprint author), DELFT DHI CONSORT,HOUSE 96,RD 23,DHAKA,BANGLADESH. RI Moore, Willard/B-6096-2016 OI Moore, Willard/0000-0001-5930-5325 NR 56 TC 49 Z9 50 U1 1 U2 8 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0025-3227 J9 MAR GEOL JI Mar. Geol. PD AUG PY 1994 VL 120 IS 1-2 BP 41 EP 61 DI 10.1016/0025-3227(94)90076-0 PG 21 WC Geosciences, Multidisciplinary; Oceanography SC Geology; Oceanography GA PF476 UT WOS:A1994PF47600005 ER PT J AU JOHNSON, SW AF JOHNSON, SW TI DEPOSITION OF TRAWL WEB ON AN ALASKA BEACH AFTER IMPLEMENTATION OF MARPOL ANNEX-V LEGISLATION SO MARINE POLLUTION BULLETIN LA English DT Article AB Deposition rate, mesh size, and weight of trawl web fragments washed ashore near Yakutat, Alaska, were monitored from 1988 to 1992 to examine the effectiveness of 1988 MARPOL Annex V legislation to reduce the amount of fishing gear and other plastics discarded or lost from ships at sea. Eight 1 km beach sections were surveyed twice each year, in March or April and September. The same sections had been surveyed previously, from 1985 to 1987. The mean deposition rate of trawl web (no. of pieces km-1 yr-1) from 1988 to 1992 declined from 10.1 to 3.8, a 60% reduction. The yearly mean deposition rate of trawl web from 1985 to 1987 was nine pieces. The mesh size of trawl web also declined: about 20% of fragments washed ashore in 1988-92 had mesh sizes > 15 cm compared to 33% in 1985-87. Mean weight of trawl web fragments was similar when comparing 1985-87 fragments and 1988-92 fragments. Beach surveys in Alaska show that the disposal or loss of trawl web at sea has declined since the implementation of MARPOL. RP NOAA, NATL MARINE FISHERIES SERV, ALASKA FISHERIES SCI CTR, AUKE BAY LAB, 11305 GLACIER HIGHWAY, JUNEAU, AK 99801 USA. NR 14 TC 7 Z9 7 U1 1 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0025-326X EI 1879-3363 J9 MAR POLLUT BULL JI Mar. Pollut. Bull. PD AUG PY 1994 VL 28 IS 8 BP 477 EP 481 DI 10.1016/0025-326X(94)90520-7 PG 5 WC Environmental Sciences; Marine & Freshwater Biology SC Environmental Sciences & Ecology; Marine & Freshwater Biology GA PE658 UT WOS:A1994PE65800003 ER PT J AU BARCOHEN, Y AF BARCOHEN, Y TI NASA FORMS NDE WORKING GROUP SO MATERIALS EVALUATION LA English DT Article RP BARCOHEN, Y (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER SOC NON-DESTRUCTIVE TEST PI COLUMBUS PA 1711 ARLINGATE LANE PO BOX 28518, COLUMBUS, OH 43228-0518 SN 0025-5327 J9 MATER EVAL JI Mater. Eval. PD AUG PY 1994 VL 52 IS 8 BP 928 EP 929 PG 2 WC Materials Science, Characterization & Testing SC Materials Science GA PC181 UT WOS:A1994PC18100006 ER PT J AU PRICE, C RIND, D AF PRICE, C RIND, D TI MODELING GLOBAL LIGHTNING DISTRIBUTIONS IN A GENERAL-CIRCULATION MODEL SO MONTHLY WEATHER REVIEW LA English DT Article ID THUNDERSTORMS; THUNDERCLOUDS; CONVECTION; WATER AB A general circulation model (GCM) is used to model global lightning distributions and frequencies. Both total and cloud-to-ground lightning frequencies are modeled using parameterizations that relate the depth of convective clouds to lightning frequencies. The model's simulations of lightning distributions in time and space show good agreement with available observations. The model's annual mean climatology shows a global lightning frequency of 77 flashes per second, with cloud-to-ground lightning making up 25% of the total. The maximum lightning activity in the GCM occurs during the Northern Hemisphere summer, with approximately 91% of all lightning occurring over continental and coastal regions. C1 NASA, GODDARD SPACE FLIGHT CTR, GODDARD INST SPACE STUDIES, GREENBELT, MD 20771 USA. COLUMBIA UNIV, NEW YORK, NY 10027 USA. RP PRICE, C (reprint author), LAWRENCE LIVERMORE NATL LAB, GLOBAL CLIMATE RES DIV, L-262, POB 808, LIVERMORE, CA 94550 USA. NR 33 TC 102 Z9 105 U1 1 U2 14 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 EI 1520-0493 J9 MON WEATHER REV JI Mon. Weather Rev. PD AUG PY 1994 VL 122 IS 8 BP 1930 EP 1939 DI 10.1175/1520-0493(1994)122<1930:MGLDIA>2.0.CO;2 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NY973 UT WOS:A1994NY97300019 ER PT J AU SOUTAR, C LU, KH AF SOUTAR, C LU, KH TI DETERMINATION OF THE PHYSICAL-PROPERTIES OF AN ARBITRARY TWISTED-NEMATIC LIQUID-CRYSTAL CELL SO OPTICAL ENGINEERING LA English DT Article DE LIQUID CRYSTAL TELEVISIONS; SPATIAL LIGHT MODULATORS; OPTICAL PROCESSING ID SPATIAL LIGHT-MODULATOR; TELEVISION; PHASE; TV AB We present an experimental procedure for the determination of the physical properties of an arbitrary twisted-nematic liquid crystal cell. No assumptions are made about the physical properties of the cell, because the commercially available devices are generally produced under proprietary conditions. The techniques developed were then used to evaluate the Jones matrix of an Epson liquid crystal television, and reasonable agreement is observed between theory and experiment. Knowledge of the Jones matrix for these devices helps to evaluate their performance as spatial light modulators in optical processing systems, and such applications are discussed. It also provides an effective means for determining the spatial quality of the liquid crystal layer. We find that there is significant variation in the birefringence across this cell, and the influence that this has on the use of the cell in optical processing systems is discussed. C1 UNIV WISCONSIN, DEPT ELECT & COMP ENGN, MADISON, WI 53706 USA. RP SOUTAR, C (reprint author), NASA, LYNDON B JOHNSON SPACE CTR, DIV TRACKING & COMMUN, HOUSTON, TX 77058 USA. NR 30 TC 116 Z9 116 U1 0 U2 4 PU SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98225 USA SN 0091-3286 EI 1560-2303 J9 OPT ENG JI Opt. Eng. PD AUG PY 1994 VL 33 IS 8 BP 2704 EP 2712 DI 10.1117/12.173544 PG 9 WC Optics SC Optics GA PB299 UT WOS:A1994PB29900031 ER PT J AU TIGIN, DV LAVRENTEV, AA GARY, CK AF TIGIN, DV LAVRENTEV, AA GARY, CK TI SPATIAL PHASE CODING FOR INCOHERENT OPTICAL PROCESSORS SO OPTICS AND LASER TECHNOLOGY LA English DT Article DE ACOUSTOOPTICS; CODING; OPTICAL MATRIX PROCESSORS; SIGNED NUMBERS AB In this paper we introduce spatial phase coding of incoherent optical signals for representing signed numbers in optical processors and present an experimental demonstration of this coding technique. If a diffraction grating, such as an acousto-optic cell, modulates a stream of light, the image of the grating can be recovered from the diffracted beam. The position of the grating image, or more precisely its phase, can be used to denote the sign of the number represented by the diffracted light. The intensity of the light represents the magnitude of the number. This technique is more economical than current methods in terms of the number of information channels required to represent a number and the amount of post processing required. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP TIGIN, DV (reprint author), ST PETERSBURG STATE ACAD AEROSP INSTRUMENTAT,ST PETERSBURG 190000,RUSSIA. NR 4 TC 1 Z9 1 U1 0 U2 0 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0030-3992 J9 OPT LASER TECHNOL JI Opt. Laser Technol. PD AUG PY 1994 VL 26 IS 4 BP 313 EP 317 DI 10.1016/0030-3992(94)90117-1 PG 5 WC Optics; Physics, Applied SC Optics; Physics GA PB727 UT WOS:A1994PB72700015 ER PT J AU RAIKAR, GN GREGORY, JC PETERS, PN AF RAIKAR, GN GREGORY, JC PETERS, PN TI OXIDATION OF COPPER BY FAST ATOMIC OXYGEN SO OXIDATION OF METALS LA English DT Article DE XPS; AES; XRD; PROFILOMETRY; REFLECTANCE ID AUGER-SPECTRA; ELECTRON SPECTROSCOPIES; PHOTOELECTRON; CU2O; CUO AB The surface composition of the oxide formed on thin-film and solid OFHC copper samples exposed to a fast-atomic-oxygen environment in a low-earth orbit on NASA's Long Duration Exposure Facility (LDEF) was investigated using X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), thin-film X-ray diffraction (TF-XRD), high-resolution profilometry, and reflectance measurements. The results confirm that it is easier to form thick copper oxide layers in the atomic oxygen ambient than is normally possible with other laboratory-based techniques. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP RAIKAR, GN (reprint author), UNIV ALABAMA,SURFACE SCI LABS,HUNTSVILLE,AL 35899, USA. NR 22 TC 11 Z9 12 U1 0 U2 3 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0030-770X J9 OXID MET JI Oxid. Met. PD AUG PY 1994 VL 42 IS 1-2 BP 1 EP 15 PG 15 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA PE995 UT WOS:A1994PE99500001 ER PT J AU ZHANG, H MOSS, WF AF ZHANG, H MOSS, WF TI USING PARALLEL BANDED LINEAR-SYSTEM SOLVERS IN GENERALIZED EIGENVALUE PROBLEMS SO PARALLEL COMPUTING LA English DT Article DE LINEAR ALGEBRA; GENERALIZED EIGENVALUE PROBLEM; BANDED LINEAR SYSTEM SOLVER; DISTRIBUTED MEMORY MULTIPROCESSOR; TIMING RESULTS ID TRIDIAGONAL SOLVERS; SUBSPACE ITERATION; MATRICES AB Subspace iteration is a reliable and cost effective method for solving positive definite banded symmetric generalized eigenproblems, especially in the case of large scale problems. This paper discusses an algorithm that makes use of two parallel banded solvers in subspace iteration. A shift is introduced to decompose the banded linear systems into relatively independent subsystems and to accelerate the iterations. With this shift, an eigenproblem is mapped efficiently into the memories of a multiprocessor and a high speedup is obtained for parallel implementations. An optimal shift is a shift that balances total computation and communication costs. Under certain conditions, we show how to estimate an optimal shift analytically using the decay rate for the inverse of a banded matrix, and how to improve this estimate. Computational results on iPSC/2 and iPSC/860 multiprocessors are presented. C1 CLEMSON UNIV,DEPT MATH SCI,CLEMSON,SC 29634. RP ZHANG, H (reprint author), NASA,LANGLEY RES CTR,ICASE,MS 132C,HAMPTON,VA 23665, USA. NR 29 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-8191 J9 PARALLEL COMPUT JI Parallel Comput. PD AUG PY 1994 VL 20 IS 8 BP 1089 EP 1105 DI 10.1016/0167-8191(94)90070-1 PG 17 WC Computer Science, Theory & Methods SC Computer Science GA PD237 UT WOS:A1994PD23700002 ER PT J AU CUCINOTTA, FA DUBEY, RR AF CUCINOTTA, FA DUBEY, RR TI ALPHA-CLUSTER DESCRIPTION OF EXCITATION-ENERGIES IN C-12(C-12,3-ALPHA)X AT 2.1A GEV SO PHYSICAL REVIEW C LA English DT Article ID GEV NUCLEON; SCATTERING; FRAGMENTATION; MODEL; C-12 AB An alpha-cluster expansion of the Glauber multiple scatteirng series is used to calculate the energy transfer spectrum to the C-12 projectile in the C-12(C-12,3alpha)X reaction at 2.1A GeV. Cluster-abrasion response functions are defined in terms of alpha-cluster wave function and the collision dynamics appropriate for heavy-ion reactions. Comparisons are made to recent quasiexclusive experimental data with good agreement found. Calculations indicate that substructures in a C-12 projectile are likely to be true spectators in fragmentation, however, with virtual states of excitation in the projectile ground state making a significant contribution to the fragmentation cross section. C1 OLD DOMINION UNIV,NORFOLK,VA 23608. RP CUCINOTTA, FA (reprint author), NASA,LANGLEY RES CTR,MAIL STOP 493,HAMPTON,VA 23665, USA. NR 24 TC 8 Z9 8 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD AUG PY 1994 VL 50 IS 2 BP 1090 EP 1096 DI 10.1103/PhysRevC.50.1090 PG 7 WC Physics, Nuclear SC Physics GA PC470 UT WOS:A1994PC47000067 PM 9969752 ER PT J AU WEISSMAN, P AF WEISSMAN, P TI ASTRONOMERS FEAST ON BIG BANGS SO PHYSICS WORLD LA English DT Editorial Material RP WEISSMAN, P (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-8585 J9 PHYS WORLD JI Phys. World PD AUG PY 1994 VL 7 IS 8 BP 7 EP 7 PG 1 WC Physics, Multidisciplinary SC Physics GA PE046 UT WOS:A1994PE04600005 ER PT J AU KRANBUEHL, DE KINGSLEY, P HART, S HASKO, G DEXTER, B LOOS, AC AF KRANBUEHL, DE KINGSLEY, P HART, S HASKO, G DEXTER, B LOOS, AC TI IN-SITU SENSOR MONITORING AND INTELLIGENT CONTROL OF THE RESIN TRANSFER MOLDING PROCESS SO POLYMER COMPOSITES LA English DT Article; Proceedings Paper CT 1992 SPE ANTEC CY 1992 CL DETROIT, MI SP SOC PLAST ENGINEERS ID CURE AB An intelligent closed-loop expert control system has been developed for automated control of the resin transfer molding process of a graphite fiber preform using an epoxy resin, E905L. The sensor model system has been developed to make intelligent decisions based on the achievement of landmarks in the cure process, such as full preform impregnation, the viscosity. and the degree of cure of the resin rather than time or temperature. In-situ frequency dependent electromagnetic sensor (FDEMS) and the Loos resin transfer model are used to monitor and control the processing properties of the epoxy resin during RTM impregnation and cure of an advanced fiber architecture stitched preform. Once correlated with viscosity (eta) and degree of cure (alpha), the FDEMS sensor monitors and the RTM processing model predicts the reaction advancement of the resin, viscosity and the impregnation of the fabric. This provides a direct means for monitoring. evaluating, and controlling intelligently the progress of the RTM process in situ in the mold throughout the fabrication process and for verification of the quality of the composites. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. VIRGINIA POLYTECH INST & STATE UNIV,DEPT ENGN SCI & MECH,BLACKSBURG,VA 24061. RP KRANBUEHL, DE (reprint author), COLL WILLIAM & MARY,DEPT CHEM,WILLIAMSBURG,VA 23187, USA. NR 12 TC 36 Z9 36 U1 0 U2 5 PU SOC PLASTICS ENG INC PI BROOKFIELD CENTER PA 14 FAIRFIELD DR, BROOKFIELD CENTER, CT 06804-0403 SN 0272-8397 J9 POLYM COMPOSITE JI Polym. Compos. PD AUG PY 1994 VL 15 IS 4 BP 299 EP 305 DI 10.1002/pc.750150408 PG 7 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA PB199 UT WOS:A1994PB19900007 ER PT J AU PONTER, AB JONES, WR JANSEN, RH AF PONTER, AB JONES, WR JANSEN, RH TI SURFACE-ENERGY CHANGES PRODUCED BY ULTRAVIOLET-OZONE IRRADIATION OF POLY(METHYL METHACRYLATE), POLYCARBONATE, AND POLYTETRAFLUOROETHYLENE SO POLYMER ENGINEERING AND SCIENCE LA English DT Article ID CONTACT-ANGLE; DROP SIZE; RADIATION; SOLIDS AB Contact angles of water and methylene iodide were measured as a function of UV/O-3 treatment time for three polymers: poly(methyl methacrylate) (PMMA), polycarbonate, and polytetrafluoroethylene (PTFE). Surface roughnesses were also measured. Surface free energies were then calculated using relationships developed by Kaelble and Neumann. The surface energy of polycarbonate was found to increase (similar to 60%) during UV/O-3 treatment. However, calculations on PMMA were hampered by the formation of a water soluble surface product. On PTFE surfaces, the UV/O-3 treatment etched the surface, causing large increases in surface roughness, rendering contact angle measurements impossible. It is concluded that care must be taken in interpreting contact angle measurements and surface energy calculations on UV/O-3 treated polymer surfaces. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. RP PONTER, AB (reprint author), UNIV SW LOUISIANA,LAFAYETTE,LA 70504, USA. NR 17 TC 22 Z9 22 U1 1 U2 7 PU SOC PLASTICS ENG INC PI BROOKFIELD CENTER PA 14 FAIRFIELD DR, BROOKFIELD CENTER, CT 06804-0403 SN 0032-3888 J9 POLYM ENG SCI JI Polym. Eng. Sci. PD AUG PY 1994 VL 34 IS 16 BP 1233 EP 1238 DI 10.1002/pen.760341602 PG 6 WC Engineering, Chemical; Polymer Science SC Engineering; Polymer Science GA PE272 UT WOS:A1994PE27200001 ER PT J AU WU, KW WICKRAMASINGHE, DT BAILEY, J TENNANT, AF AF WU, KW WICKRAMASINGHE, DT BAILEY, J TENNANT, AF TI ACCRETION GEOMETRY OF SYNCHRONOUSLY ROTATING MAGNETIC CATACLYSMIC VARIABLES - THEORIES VERSUS OBSERVATIONS SO PROCEEDINGS ASTRONOMICAL SOCIETY OF AUSTRALIA LA English DT Article ID HERCULIS-TYPE SYSTEMS; AM; FIELD; CONFIGURATIONS; BINARIES; POLE AB We review the magnetic locking of the white dwarf and the companion star in AM Herculis-type binaries for various white dwarf magnetic field structures, and compare the theoretical results with observations. The model in which the white dwarf has a dipole plus a quadrupole field is found to be in closest agreement with the recent observations. C1 AUSTRALIAN NATL UNIV,DEPT MATH,CANBERRA,ACT 0200,AUSTRALIA. ANGLO AUSTRALIAN OBSERV,EPPING,NSW 2121,AUSTRALIA. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP WU, KW (reprint author), UNIV SYDNEY,SCH PHYS,THEORET ASTROPHYS RES CTR,SYDNEY,NSW 2006,AUSTRALIA. NR 12 TC 4 Z9 4 U1 0 U2 0 PU C S I R O PUBLICATIONS PI COLLINGWOOD PA 150 OXFORD ST, PO BOX 1139, COLLINGWOOD VICTORIA 3066, AUSTRALIA SN 0066-9997 J9 P ASTRON SOC AUST JI Proc. Astron. Soc. Aust. PD AUG PY 1994 VL 11 IS 2 BP 198 EP 200 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ784 UT WOS:A1994NZ78400013 ER PT J AU MANSPERGER, CS KAITCHUCK, RH GARNAVICH, PM DINSHAW, N ZAMKOFF, E AF MANSPERGER, CS KAITCHUCK, RH GARNAVICH, PM DINSHAW, N ZAMKOFF, E TI HL CANIS-MAJORIS IN PREOUTBURST AND SS CYGNI - THE INTEROUTBURST DISK INSTABILITY SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID ACCRETION DISKS; VERTICAL STRUCTURE; BINARY-SYSTEMS; DWARF NOVAE; OUTBURST; DYNAMICS; MODEL; SPECTROSCOPY; STABILITY; EVOLUTION AB SS Cygni and HL Canis Majoris were observed by IUE for three consecutive nights in November of 1992. During the first two nights, simultaneous photometric ground-based observations of SS Cyg were made at the Ball State University Observatory. Observations of SS Cyg and HL CMa were also obtained simultaneously with the 90-inch telescope at the Steward Observatory on the last two nights of the IUE run. These spectroscopic observations covered the wavelength range from 4 1 00 to 5000 angstrom, while the spectra taken with the short wavelength camera on IUE resulted in wavelength coverage from 1150 angstrom to 1980 A. SS Cyg is a U Geminorum-type dwarf nova with an orbital period of 6.6 hr. Good simultaneous UV and optical orbital coverage was obtained for this system. HL CMa is a Z Camelopardalis-type dwarf nova with a mean outburst interval of 15 days. The AAVSO reports that this system was in outburst 4 days after the observing run. Therefore, HL CMa may have been in a preoutburst state during these observations. Optical spectra of HL CMa indicate a warm front passed through the outer disk four days before outburst, but no changes were seen in the UV spectra. Signs of a preoutburst state were observed to develop in SS Cyg, but no outburst occurred for another 30 days. C1 BALL STATE UNIV,DEPT PHYS & ASTRON,MUNCIE,IN 47306. DAO,VICTORIA,BC,CANADA. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. NASA,GODDARD SPACE FLIGHT CTR,GSFC,HUGHES STX CO,GREENBELT,MD 20771. RP MANSPERGER, CS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GSFC,COMP SCI CORP,IUE,CODE 6849,GREENBELT,MD 20771, USA. NR 26 TC 2 Z9 2 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 AUG PY 1994 VL 106 IS 702 BP 858 EP 868 DI 10.1086/133453 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD743 UT WOS:A1994PD74300006 ER PT J AU BRANDT, JC HEAP, SR BEAVER, EA BOGGESS, A CARPENTER, KG EBBETS, DC HUTCHINGS, JB JURA, M LECKRONE, DS LINSKY, JL MARAN, SP SAVAGE, BD SMITH, AM TRAFTON, LM WALTER, FM WEYMANN, RJ AKE, TB BRUHWEILER, F CARDELLI, JA LINDLER, DJ MALUMUTH, E RANDALL, CE ROBINSON, R SHORE, SN WAHLGREN, G AF BRANDT, JC HEAP, SR BEAVER, EA BOGGESS, A CARPENTER, KG EBBETS, DC HUTCHINGS, JB JURA, M LECKRONE, DS LINSKY, JL MARAN, SP SAVAGE, BD SMITH, AM TRAFTON, LM WALTER, FM WEYMANN, RJ AKE, TB BRUHWEILER, F CARDELLI, JA LINDLER, DJ MALUMUTH, E RANDALL, CE ROBINSON, R SHORE, SN WAHLGREN, G TI THE GODDARD HIGH-RESOLUTION SPECTROGRAPH - INSTRUMENT, GOALS, AND SCIENCE RESULTS SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID DIFFUSE CLOUDS; ZETA-OPHIUCHI; ELEMENTAL ABUNDANCES; SPACE TELESCOPE; HEAVY-ELEMENTS; RESONANCE LINE; ALPHA-TAURI; IUE SPECTRA; B-II; STARS AB The Goddard High Resolution Spectrograph (GHRS), currently in Earth orbit on the Hubble Space Telescope (HST), operates in the wavelength range 1150-3200 angstrom with spectral resolutions (lambda/deltalambda) of approximately 2 x 10(3), 2 X 10(4), and 1 X 10(5). The instrument and its development from inception, its current status, the approach to operations, representative results in the major areas of the scientific goals, and prospects for the future are described. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. DOMINION ASTROPHYS OBSERV,VICTORIA V8X 4M6,BC,CANADA. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. UNIV COLORADO,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. SUNY STONY BROOK,STONY BROOK,NY 11794. CARNEGIE INST WASHINGTON,OBSERV,PASADENA,CA 91101. NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON PROGRAM,GREENBELT,MD 20771. CATHOLIC UNIV AMER,NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. INDIANA UNIV,DEPT PHYS & ASTRON,S BEND,IN 46634. BALL AEROSP SYST GRP,BOULDER,CO 80306. NATL INST STAND & TECHNOL,BOULDER,CO 80309. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. RP BRANDT, JC (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,CAMPUS BOX 392,BOULDER,CO 80309, USA. RI heap, sara/E-2237-2012; Carpenter, Kenneth/D-4740-2012; Randall, Cora/L-8760-2014 OI Randall, Cora/0000-0002-4313-4397 NR 69 TC 67 Z9 67 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 AUG PY 1994 VL 106 IS 702 BP 890 EP 908 DI 10.1086/133457 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD743 UT WOS:A1994PD74300010 ER PT J AU MEYER, P AF MEYER, P TI A PARAMETRIC APPROACH FOR THE GEOCODING OF AIRBORNE VISIBLE INFRARED IMAGING SPECTROMETER (AVIRIS) DATA IN RUGGED TERRAIN SO REMOTE SENSING OF ENVIRONMENT LA English DT Article AB A geocoding procedure for remotely sensed data of airborne systems in rugged terrain is affected by several factors: buffeting of the aircraft by turbulence, variations in ground speed, changes in altitude, attitude variations, and surface topography. The current investigation was carried from Central Switzerland, using two Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) scenes out of NASA's Multi Aircraft Campaign (MAC) in Europe (1991). The first scene was acquired over flat and hilly terrain and the second over a mountainous area with steep slopes. The parametric approach reconstructs for every pixel the observation geometry based on the flight line, aircraft attitude, and surface topography. Aircraft navigation data, instrument engineering data, information from a conical radar tracking system, and a digital elevation model are used. To prevent changes to the radiometric characteristics, the original value is selected by an improved extraction algorithm, thereby eliminating the need to interpolate the values. The results are visually checked for correspondence at locations with different slope and aspect angles by overlaying scanned forest maps and digitized shorelines of the Swiss Topographical Map. This validation is completed by a quantization of the spatial deviation at selected points and a comparison with an improved nonparametric approach. In general, the results show very good correspondence with the maps. The algorithm reported in this article is a necessary base to apply georadiometric correction methods for slope-aspect-dependent illumination corrections, atmospheric corrections, and to use AVIRIS data within single-pixel based information systems for land use classification. C1 JET PROP LAB,PASADENA,CA 91109. NR 22 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 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG PY 1994 VL 49 IS 2 BP 118 EP 130 DI 10.1016/0034-4257(94)90048-5 PG 13 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA PE637 UT WOS:A1994PE63700003 ER PT J AU RIGNOT, E WAY, JB AF RIGNOT, E WAY, JB TI MONITORING FREEZE-THAW CYCLES ALONG NORTH-SOUTH ALASKAN TRANSECTS USING ERS-1 SAR SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID BUDGET AB Monitoring freeze-thaw cycles of high latitude terrestrial ecosystems is useful for estimating the length of the growing season and annual productivity in the tundra and in boreal forests, for estimating potential damage to living plants due to frost drought, and for evaluating major changes in heat fluxes between land and atmosphere. At microwave frequencies, freezing results in a dramatic decrease of the dielectric constant of soil and vegetation, which significantly alters their radar scattering properties. In this article, we investigate the possibility of monitoring freeze-thaw cycles of terrestrial ecosystems using C-band frequency (5.3 GHz), vertical transmit and receive polarization, synthetic-aperture radar (SAR) data gathered by the European Space Agency's Earth Remote Sensing satellite (ERS-1). Repeat-pass SAR images are mosaicked together along a north-south transect across Alaska, coregistered, and analyzed using a change detection algorithm that determines when the landscape freezes based on a decrease in radar backscatter greater than 3 dB relative to a known thawed, wet state of the landscape. Air-temperature recordings from seven airport weather stations and in situ observations from three monitored forest stands in interior Alaska concur to indicate SAR accurately maps frozen areas across the entire state. The technique does not apply to open water areas because calm water and frozen water are confused. Elsewhere, ERS-1 SAR could monitor thaw/freeze transitions of terrestrial ecosystems at the regional scale, at a spatial resolution of several tens of meters and independent of cloud cover and vegetation type. RP RIGNOT, E (reprint author), JET PROP LAB,MAIL STOP 300-243,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 22 TC 57 Z9 57 U1 1 U2 15 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG PY 1994 VL 49 IS 2 BP 131 EP 137 DI 10.1016/0034-4257(94)90049-3 PG 7 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA PE637 UT WOS:A1994PE63700004 ER PT J AU RIGNOT, E WAY, JB MCDONALD, K VIERECK, L WILLIAMS, C ADAMS, P PAYNE, C WOOD, W SHI, JC AF RIGNOT, E WAY, JB MCDONALD, K VIERECK, L WILLIAMS, C ADAMS, P PAYNE, C WOOD, W SHI, JC TI MONITORING OF ENVIRONMENTAL-CONDITIONS IN TAIGA FORESTS USING ERS-1 SAR SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID MICROWAVE SIGNATURES; MODEL; VEGETATION; ALASKA; SOIL AB Synthetic-aperture radar images of a forest site near Manley Hot Springs (64-degrees-N, 151-degrees-W), Alaska, were collected between August 1991 and December 1991, day and night, every 3 days, at C-band frequency (lambda = 5.7 cm), vertical receive and transmit polarization, by the European Space Agency first Remote Sensing Satellite, ERS-1. During the same period, air and soil temperatures and dielectric and gravimetric moisture properties of the forest canopy and forest floor were monitored in three forest stands dominated, respectively, by black spruce (Picea mariana), white spruce (Picea glauca), and balsam poplar (Populus balsamifera). The calibrated ERS-1 radar backscatter values, sigma-degree, of the forest stands are shown to exhibit a pronounced temporal pattern, with little separability between tree species. The largest change in sigma-degree, a 3-dB decrease almost independent of tree species, is observed in early winter when the soil and vegetation freeze. In the summer, temporal fluctuations in sigma-degree are about 1-2 dB in magnitude, depending on tree species. Diurnal variations in sigma-degree are as large as 2 dB during fall freeze-up, and less than 1 dB in summer and winter. These temporal variations in radar backscatter from the forest are interpreted using the MIMICS radar backscatter model and the in situ surface observations as due to changes in the dielectric properties of the forest floor and forest canopy induced by precipitation (summer), drought (fall), and freezing (fall-winter) events. In winter, sigma-degree increases across the entire landscape, probably because of volume scattering from large depth hoar ice crystals forming in the snow pack. C1 INST NO FORESTRY,FAIRBANKS,AK. UNIV CALIF SANTA BARBARA,DEPT GEOG,SANTA BARBARA,CA 93106. RP RIGNOT, E (reprint author), JET PROP LAB,MS 300-243,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 20 TC 47 Z9 48 U1 1 U2 5 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD AUG PY 1994 VL 49 IS 2 BP 145 EP 154 DI 10.1016/0034-4257(94)90051-5 PG 10 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA PE637 UT WOS:A1994PE63700006 ER PT J AU GOLDEN, GY AF GOLDEN, GY TI ON THE WAY TO JUPITER - PSYCHOLOGICAL DIMENSIONS OF THE GALILEO MISSION SO SOCIAL STUDIES OF SCIENCE LA English DT Article ID STRESS AB Emotions are a seldom-studied facet of the creative process in science and engineering. This paper describes a study of emotions in scientists and engineers on the Galileo mission to Jupiter, at the Jet Propulsion Laboratory in Pasadena, California, from 1987-90. Although the spacecraft was finally launched in 1989, and is now en route to Jupiter, the Challenger Shuttle accident severely threatened the Project's survival in 1986, placing many people under serious stress, and triggering depression in some. The paper describes the nature of the depressions (an overwhelming sense of futility), how people coped with the associated problems and emotions (social support was a critical variable), and how the depressions resolved. The findings have implications for future interrupted missions: managers can ease, and possibly help end, such depressions by empathizing with the experience of futility, by helping people to make significant shifts in task or position within a project, and by recognizing interim achievement. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 18 TC 2 Z9 2 U1 0 U2 3 PU SAGE PUBLICATIONS LTD PI LONDON PA 6 BONHILL STREET, LONDON, ENGLAND EC2A 4PU SN 0306-3127 J9 SOC STUD SCI JI Soc. Stud. Sci. PD AUG PY 1994 VL 24 IS 3 BP 463 EP 511 DI 10.1177/030631279402400302 PG 49 WC History & Philosophy Of Science SC History & Philosophy of Science GA PG144 UT WOS:A1994PG14400002 PM 11639317 ER PT J AU BROWN, JC CORREIA, E FARNIK, F GARCIA, H HENOUX, JC LAROSA, TN MACHADO, ME NAKAJIMA, H PRIEST, ER AF BROWN, JC CORREIA, E FARNIK, F GARCIA, H HENOUX, JC LAROSA, TN MACHADO, ME NAKAJIMA, H PRIEST, ER TI ENERGY-RELEASE IN SOLAR-FLARES SO SOLAR PHYSICS LA English DT Article; Proceedings Paper CT 2nd Flares22 Workshop on Recent Observations and Theories of Solar Flares CY MAY 22-28, 1993 CL OTTAWA, CANADA SP NATL RES COUNCIL CANADA, SCOSTEP ID FAST MAGNETIC RECONNECTION; X-RAY-BURSTS; MODELS AB Team 2 of the Ottawa FLARES 22 Workshop dealt with observational and theoretical aspects of the characteristics and processes of energy release in flares. Main results summarized in this article stress the global character of the flaring phenomenon in active regions, the importance of discontinuities in magnetic connectivity, the role of field-aligned currents in free energy storage, and the fragmentation of energy release in time and space. C1 EPUSP,CRAAE,CTR RADIO ASTRON & SPACE APPLICAT,SAO PAULO,BRAZIL. NOAA,SPACE ENVIRONM LAB,BOULDER,CO 80303. OBSERV PARIS,DASOP,F-92195 MEUDON,FRANCE. NASA,MSFC,SPACE SCI LAB,HUNTSVILLE,AL. CONAE,BUENOS AIRES,DF,ARGENTINA. NOBEYAMA RADIO OBSERV,NOBEYAMA,JAPAN. UNIV ST ANDREWS,ST ANDREWS,FIFE,SCOTLAND. ASTRON INST,ONDREJOV,CZECH REPUBLIC. RP BROWN, JC (reprint author), UNIV GLASGOW,DEPT PHYS & ASTRON,GLASGOW,LANARK,SCOTLAND. RI Correia, Emilia/F-6802-2012; Farnik, Frantisek/G-9010-2014 NR 35 TC 13 Z9 13 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD AUG PY 1994 VL 153 IS 1-2 BP 19 EP 31 DI 10.1007/BF00712490 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ775 UT WOS:A1994PQ77500003 ER PT J AU BENZ, AO KOSUGI, T ASCHWANDEN, MJ BANKA, SG CHUPP, EL ENOME, S GARCIA, H HOLMAN, GD KURT, VG SAKAO, T STEPANOV, AV VOLWERK, M AF BENZ, AO KOSUGI, T ASCHWANDEN, MJ BANKA, SG CHUPP, EL ENOME, S GARCIA, H HOLMAN, GD KURT, VG SAKAO, T STEPANOV, AV VOLWERK, M TI PARTICLE-ACCELERATION IN FLARES SO SOLAR PHYSICS LA English DT Article ID HARD X-RAY; THERMAL NONTHERMAL MODEL; SOLAR-FLARES; DYNAMIC SPECTRA; TELESCOPE HXT; RADIO; MICROWAVE; ELECTRON; BURSTS; DIRECTIVITY AB Particle acceleration is intrinsic to the primary energy release in the impulsive phase of solar flares, and we cannot understand flares without understanding acceleration. New observations in soft and hard X-rays, gamma-rays and coherent radio emissions are presented, suggesting flare fragmentation in time and space. X-ray and radio measurements exhibit at least five different time scales in flares. In addition, same new observations of delayed acceleration signatures are also presented. The theory of acceleration by parallel electric fields is used to model the spectral shape and evolution of hard X-rays. The possibility of the appearance of double layers is further investigated. C1 NATL ASTRON OBSERV, MITAKA, TOKYO 181, JAPAN. UNIV MARYLAND, DEPT ASTRON, COLLEGE PK, MD 20742 USA. USN, RES LAB, EO HULBURT CTR SPACE RES, WASHINGTON, DC 20375 USA. UNIV NEW HAMPSHIRE, DEPT PHYS, DURHAM, NH 03824 USA. UNIV NEW HAMPSHIRE, CTR SPACE SCI, DURHAM, NH 03824 USA. NOBEYAMA RADIO OBSERV, NAGANO 381413, JAPAN. NOAA, SPACE ENVIRONM LAB, BOULDER, CO 80303 USA. NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. INST NUCL PHYS, MOSCOW, RUSSIA. NATL ASTRON OBSERV, MITAKA, TOKYO 181, JAPAN. CRIMEAN ASTROPHYS OBSERV, KATZIVELY, UKRAINE. RP BENZ, AO (reprint author), ETH ZURICH, INST ASTRON, CH-8092 ZURICH, SWITZERLAND. RI Holman, Gordon/C-9548-2012 NR 47 TC 13 Z9 13 U1 0 U2 2 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD AUG PY 1994 VL 153 IS 1-2 BP 33 EP 53 DI 10.1007/BF00712491 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ775 UT WOS:A1994PQ77500004 ER PT J AU SCHMIEDER, B PERES, G ENOME, S FALCIANI, R HEINZEL, P HENOUX, JC MARISKA, J REALE, F RILEE, ML ROMPOLT, B SHIBASAKI, K STEPANOV, AV WULSER, JP ZARRO, D ZHARKOVA, V AF SCHMIEDER, B PERES, G ENOME, S FALCIANI, R HEINZEL, P HENOUX, JC MARISKA, J REALE, F RILEE, ML ROMPOLT, B SHIBASAKI, K STEPANOV, AV WULSER, JP ZARRO, D ZHARKOVA, V TI ENERGY-TRANSPORT AND DYNAMICS SO SOLAR PHYSICS LA English DT Article ID BRAGG CRYSTAL SPECTROMETER; K-LINE PROFILES; X-RAY TELESCOPE; SOLAR-A MISSION; H-ALPHA; CHROMOSPHERIC FLARES; NONTHERMAL PROCESSES; PION DECAY; ATMOSPHERE; ELECTRONS AB We report findings concerning energy transport and dynamics in flares during the impulsive and gradual phases based on new ground-based and space observations (notably from Yohkoh). A preheating sometimes occurs during the impulsive phase. Ca XIX line shifts are confirmed to be good tracers of bulk plasma motions, although strong blue shifts are not as frequent as previously claimed. They often appear correlated with hard X-rays but, for some events, the concept that electron beams provide the whole energy input to the thermal component seems not to apply. Theory now yields: new diagnostics of low-energy proton and electron beams; accurate hydrodynamical modeling of pulse beam heating of the atmosphere; possible diagnostics of microflares (based on X-ray line ratio or on loop variability); and simulated images of chromospheric evaporation fronts. For the gradual phase, the continual reorganization of magnetic field lines over active regions determines where and when magnetic reconnection, the mechanism favoured for energy release, will occur. Spatial and temporal fragmentation of the energy release, observed at different wavelengths, is considered to be a factor as well in energy transport and plasma dynamics. C1 OSSERV ASTROFIS CATANIA, I-95125 CATANIA, ITALY. NOBEYAMA RADIO OBSERV, MINAMISA KU, NAGANO 38413, JAPAN. DIPARTIMENTO ASTRON, I-50125 FLORENCE, ITALY. ACAD SCI CZECH REPUBL, INST ASTRON, CR-25165 ONDREJOV, CZECH REPUBLIC. NRL, WASHINGTON, DC 20375 USA. IST OSSERV ASTRON, I-90134 PALERMO, ITALY. CORNELL UNIV, PLASMA STUDIES LAB, NEW YORK, NY USA. UNIV WROCLAW, INST ASTRON, PL-51622 WROCLAW, POLAND. CRIMEAN ASTROPHYS OBSERV, KATZIVELY, UKRAINE. UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. KIEV TG SHEVCHENKO STATE UNIV, DIV ASTRON, KIEV 25022, UKRAINE. UNIV GLASGOW, DEPT PHYS & ASTRON, GLASGOW G12 8QQ, LANARK, SCOTLAND. RP OBSERV PARIS, SECT MEUDON, F-92195 MEUDON, FRANCE. RI Heinzel, Petr/G-9014-2014; OI Reale, Fabio/0000-0002-1820-4824 NR 62 TC 5 Z9 5 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 EI 1573-093X J9 SOL PHYS JI Sol. Phys. PD AUG PY 1994 VL 153 IS 1-2 BP 55 EP 72 DI 10.1007/BF00712492 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PQ775 UT WOS:A1994PQ77500005 ER PT J AU HARRIS, PR AF HARRIS, PR TI A CASE FOR PERMANENT LUNAR DEVELOPMENT AND INVESTMENT SO SPACE POLICY LA English DT Article AB This Viewpoint argues that the promise of the Apollo Moon landings was not fully realized and that we should now think seriously about developing a lunar base. This could be effective in a number of economic and environmental sectors and would provide a focus for conversion of the defence industry to more peaceful activities. However, the existing UN space treaties would need to be amended and a new authority created to govern activities on the Moon. C1 NASA,WASHINGTON,DC 20546. NR 6 TC 2 Z9 2 U1 0 U2 1 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, OXON, ENGLAND OX5 1GB SN 0265-9646 J9 SPACE POLICY JI Space Policy PD AUG PY 1994 VL 10 IS 3 BP 187 EP 188 DI 10.1016/0265-9646(94)90069-8 PG 2 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA PD846 UT WOS:A1994PD84600004 ER PT J AU LINDERMAN, JK GOSSELINK, KL AF LINDERMAN, JK GOSSELINK, KL TI THE EFFECTS OF SODIUM-BICARBONATE INGESTION ON EXERCISE PERFORMANCE SO SPORTS MEDICINE LA English DT Article RP LINDERMAN, JK (reprint author), NASA,AMES RES CTR,DIV LIFE SCI 23911,MOFFETT FIELD,CA 94035, USA. NR 0 TC 42 Z9 44 U1 0 U2 11 PU ADIS INTERNATIONAL LTD PI AUCKLAND PA 41 CENTORIAN DR, PRIVATE BAG 65901, MAIRANGI BAY, AUCKLAND 10, NEW ZEALAND SN 0112-1642 J9 SPORTS MED JI Sports Med. PD AUG PY 1994 VL 18 IS 2 BP 75 EP 80 DI 10.2165/00007256-199418020-00001 PG 6 WC Sport Sciences SC Sport Sciences GA PC904 UT WOS:A1994PC90400001 PM 9132921 ER PT J AU YUNIS, IS CARNEY, KS AF YUNIS, IS CARNEY, KS TI STRUCTURAL RELIABILITY TECHNIQUES APPLIED TO PLUME IMPINGEMENT LOADING OF THE SPACE-STATION-FREEDOM PHOTOVOLTAIC ARRAY SO STRUCTURAL SAFETY LA English DT Article DE STRUCTURES; STRUCTURAL DYNAMICS; RELIABILITY; MONTE CARLO; SPACE STATION AB A new aerospace application of structural reliability techniques is presented, where the applied forces depend on many probabilistic variables. This application is the plume impingement loading of the Space Station Freedom Photovoltaic Arrays, When the space shuttle berths with Space Station Freedom it must brake and maneuver towards the berthing point using its primary jets. The jet exhaust, or plume, may cause high loads on the photovoltaic arrays. The many parameters governing this problem are highly uncertain and random. An approach, using techniques from structural reliability, as opposed to the accepted deterministic methods, is presented which assesses the probability of failure of the array mast due to plume impingement loading. A Monte Carlo simulation of the berthing approach is used to determine the probability distribution of the loading. A probability distribution is also determined for the strength of the array. Structural reliability techniques are then used to assess the array mast design. These techniques are found to be superior to the standard deterministic dynamic transient analysis, for this class of problem. The results show that the probability of failure of the current array mast design due to the examined failure modes is minute. Significantly, this paper details a structural reliability analysis of a complex aerospace structure for which little statistical information is available. RP YUNIS, IS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-4730 J9 STRUCT SAF JI Struct. Saf. PD AUG PY 1994 VL 15 IS 1-2 BP 85 EP 110 DI 10.1016/0167-4730(94)90054-X PG 26 WC Engineering, Civil SC Engineering GA PF309 UT WOS:A1994PF30900007 ER PT J AU HOFFMAN, EK BIRD, RK DICUS, DL AF HOFFMAN, EK BIRD, RK DICUS, DL TI EFFECT OF BRAZE PROCESSING ON SCS-6 BETA-21S TITANIUM MATRIX COMPOSITES SO WELDING JOURNAL LA English DT Article DE BRAZING; BRAZING TITANIUM; TITANIUM COMPOSITES; BRAZING FILLER METALS; TI-BASED FILLER METAL; TI-CU-NI FILLER METAL; TENSILE PROPERTIES; FRACTOGRAPHY; METALLOGRAPHY; AIRFRAME STRUCTURES AB This study was undertaken to investigate the effects of braze processing on the microstructure and tensile properties of [0/90]s laminates of SCS-6 SiC fiber-reinforced beta21S (Ti-15Mo-2.7Nb-3Al0.25Si, wt-%) titanium matrix composites (TMC). TMC panels were exposed to brazing processes employing two forms of commercially available Ti-15Cu-15Ni brazing filler metal. Tensile specimens from the panels were tested at room temperature, 1200-degrees-F (649-degrees-C), and 1500-degrees-F (816-degrees-C), and the resulting properties were compared to those of TMC specimens subjected to only a stabilization heat treatment. The results showed that the brazing processes investigated had little effect on the tensile properties of the TMC. The application of the brazing filler metals to the TMC surface resulted in a braze-transformed surface layer that exhibited brittle fracture, while the bulk of the beta21S matrix exhibited a ductile fracture morphology. Metallurgical analysis showed that the brazing filler metal constituents did not diffuse into the carbon-enriched outer layers of the fiber or affect the fiber/matrix reaction zone thickness. Thus, the lack of a significant effect of the brazing processes on the TMC tensile behavior can be primarily attributed to the limited embrittlement of the matrix and the absence of deleterious effects on the fibers and the fiber/matrix interface. RP HOFFMAN, EK (reprint author), NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23665, USA. NR 8 TC 2 Z9 2 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 AUG PY 1994 VL 73 IS 8 BP S185 EP S191 PG 7 WC Metallurgy & Metallurgical Engineering SC Metallurgy & Metallurgical Engineering GA PA341 UT WOS:A1994PA34100014 ER PT J AU SHEEHY, JA BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H AF SHEEHY, JA BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H TI THEORETICAL-STUDY OF THE NITRIC-OXIDE EPSILON AND 11000-ANGSTROM BANDS SO CHEMICAL PHYSICS LETTERS LA English DT Article ID NO; LIFETIMES; FLUORESCENCE; STATES; SPECTROSCOPY; PREDISSOCIATION; COEFFICIENTS; 2-SIGMA+ AB Potential-energy curves, transition-moment functions, Einstein A coefficients, and radiative lifetimes associated with the D2SIGMA+ Rydberg state of nitric oxide are calculated in large Gaussian basis sets employing internally contracted multireference configuration interaction from state-averaged complete-active-space self-consistent-field wavefunctions. The epsilon (D2SIGMA+-X2PI) and 11000 angstrom (D2SIGMA+-A2SIGMA+) bands are the main focus of this work; a D2SIGMA+ (nu' = 0) radiative lifetime of 19.23 ns is obtained, in excellent agreement with experimental values. RP SHEEHY, JA (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035, USA. NR 29 TC 16 Z9 16 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUL 29 PY 1994 VL 225 IS 1-3 BP 221 EP 228 DI 10.1016/0009-2614(94)00608-3 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA PA037 UT WOS:A1994PA03700033 ER PT J AU ORTON, GS FRIEDSON, AJ YANAMANDRAFISHER, PA CALDWELL, J HAMMEL, HB BAINES, KH BERGSTRALH, JT MARTIN, TZ WEST, RA VEEDER, GJ LYNCH, DK RUSSELL, R MALCOM, ME GOLISCH, WF GRIEP, DM KAMINSKI, CD TOKUNAGA, AT HERBST, T SHURE, M AF ORTON, GS FRIEDSON, AJ YANAMANDRAFISHER, PA CALDWELL, J HAMMEL, HB BAINES, KH BERGSTRALH, JT MARTIN, TZ WEST, RA VEEDER, GJ LYNCH, DK RUSSELL, R MALCOM, ME GOLISCH, WF GRIEP, DM KAMINSKI, CD TOKUNAGA, AT HERBST, T SHURE, M TI SPATIAL-ORGANIZATION AND TIME-DEPENDENCE OF JUPITER TROPOSPHERIC TEMPERATURES, 1980-1993 SO SCIENCE LA English DT Article ID EQUATORIAL; ATMOSPHERE AB The spatial organization and time dependence of Jupiter's temperatures near 25O-millibar pressure were measured through a jovian year by imaging thermal emission at 18 micrometers. The temperature field is influenced by seasonal radiative forcing, and its banded organization is closely correlated with the visible cloud field. Evidence was found for a quasi-periodic oscillation of temperatures in the Equatorial Zone, a correlation between tropospheric and stratospheric waves in the North Equatorial Belt, and slowly moving thermal features in the North and South Equatorial Belts. There appears to be no common relation between temporal changes of temperature and changes in the visual albedo of the various axisymmetric bands. C1 INST SPACE & TERR SCI,SPACE ASTROPHYS LAB,CONCORD L4K 3C8,ON,CANADA. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. NASA,WASHINGTON,DC 20546. TRW CO INC,REDONDO BEACH,CA 90278. AEROSP CORP,SPACE SCI LAB,LOS ANGELES,CA 90009. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. MAX PLANCK INST ASTRON,HEIDELBERG,GERMANY. RP ORTON, GS (reprint author), CALTECH,JET PROP LAB,MS 169-237,PASADENA,CA 91109, USA. NR 38 TC 36 Z9 36 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 JUL 29 PY 1994 VL 265 IS 5172 BP 625 EP 631 DI 10.1126/science.265.5172.625 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NZ538 UT WOS:A1994NZ53800023 PM 17752758 ER PT J AU MARDER, SR GORMAN, CB MEYERS, F PERRY, JW BOURHILL, G BREDAS, JL PIERCE, BM AF MARDER, SR GORMAN, CB MEYERS, F PERRY, JW BOURHILL, G BREDAS, JL PIERCE, BM TI A UNIFIED DESCRIPTION OF LINEAR AND NONLINEAR POLARIZATION IN ORGANIC POLYMETHINE DYES SO SCIENCE LA English DT Article ID ORDER OPTICAL SUSCEPTIBILITIES; BOND-LENGTH ALTERNATION; ELECTRONIC HYPERPOLARIZABILITY; MOLECULES; POLARIZABILITIES; BENZENE AB An internal or external electric field F can drive the chemical structure, bond order alternation, and electronic structure of linear polymethine dyes from a neutral, bond-alternated, polyene-like structure, through a cyanine-like structure, and ultimately to a zwitterionic (charge-separated) bond-alternated structure. As the structure evolves under the influence of F, the linear polarizability alpha, the first hyperpolarizability beta, and the second hyperpolarizability gamma are seen to be derivatives, with respect to F, of their next lower order polarization (for alpha) or polarizability (for beta and gamma). These derivative relations provide a unified picture of the dependence of the polarizability and hyperpolarizabilities on the structure in linear polymethine dyes. In addition, they allow for predictions of structure-property relations of higher order hyperpolarizabilities. C1 CALTECH,CTR MOLEC MAT RESOURCE,PASADENA,CA 91125. UNIV MONS,CTR RES MOLEC ELECTR & PHOTON,B-7000 MONS,BELGIUM. HUGHES AIRCRAFT CO,LOS ANGELES,CA 90009. RP MARDER, SR (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI Gorman, Christopher/A-3463-2008; Bredas, Jean-Luc/A-3431-2008; Perry, Joseph/B-7191-2011 OI Gorman, Christopher/0000-0001-7367-2965; Bredas, Jean-Luc/0000-0001-7278-4471; Perry, Joseph/0000-0003-1101-7337 NR 28 TC 520 Z9 521 U1 2 U2 54 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUL 29 PY 1994 VL 265 IS 5172 BP 632 EP 635 DI 10.1126/science.265.5172.632 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NZ538 UT WOS:A1994NZ53800024 PM 17752759 ER PT J AU BECKER, L BADA, JL WINANS, RE HUNT, JE BUNCH, TE FRENCH, BM AF BECKER, L BADA, JL WINANS, RE HUNT, JE BUNCH, TE FRENCH, BM TI FULLERENES IN THE 1.85-BILLION-YEAR-OLD SUDBURY IMPACT STRUCTURE SO SCIENCE LA English DT Article ID EARTHS EARLY ATMOSPHERE; MASS-SPECTROMETRY; ALLENDE METEORITE; ION FORMATION; C-60; CARBON; C60 AB Fullerenes (C-60 and C-70) have been identified by laser desorption, laser desorption postionization, and high-resolution electron-impact mass spectrometry in shock-produced breccias (Onaping Formation) of the Sudbury impact structure in Ontario, Canada, The C-60 isotope is present at a level of a few parts per million. The fullerenes were likely synthesized within the impact plume from the carbon contained in the bolide. The oxidation of the fullerenes during the 1.85 billion years of exposure was apparently prevented by the presence of sulfur in the form of sulfide-silicate complexes associated with the fullerenes. C1 ARGONNE NATL LAB,DIV CHEM,ARGONNE,IL 60439. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. NASA HEADQUARTERS,WASHINGTON,DC 20546. RP BECKER, L (reprint author), UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,LA JOLLA,CA 92093, USA. NR 51 TC 102 Z9 106 U1 4 U2 18 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUL 29 PY 1994 VL 265 IS 5172 BP 642 EP 645 DI 10.1126/science.11536660 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NZ538 UT WOS:A1994NZ53800027 PM 11536660 ER PT J AU KHAKOO, MA BECKMANN, CE TRAJMAR, S CSANAK, G AF KHAKOO, MA BECKMANN, CE TRAJMAR, S CSANAK, G TI ELECTRON-IMPACT EXCITATION OF THE NS[3/2]J=2,1(O) AND NS'[1/2]J=0,1(O) LEVELS OF NE, AR, KR AND XE SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID SCATTERING CROSS-SECTIONS; HEAVY NOBLE-GASES; INCIDENT ENERGIES; RARE-GASES; KRYPTON; STATES AB Relative differential cross sections for electron-impact excitation of the four lowest electronic levels (ns[3/2]J=2 and 1 and ns'[1/2]J=0 and 1) were measured for Ne, Ar, Kr and Xe at 30 eV impact energy and for Kr and Xe at 20 eV impact energy for a range of scattering angles from 0-degrees to 134-degrees. The aim of the present work was: to improve the quality of existing data, to extend the measurements to small scattering angles, to determine whether statistical weight (branching) ratios represent the ns[3/2]2o to ns'[1/2]0 DCS ratios (r) and to compare the experimental results with the predictions of non-relativistic and relativistic first-order scattering theories. We found that the experimental ratios r closely correspond to statistical weight ratios for Ne and Ar at all scattering angles, for Kr at most angles, but seriously deviate from statistical weight ratios for Xe at all angles. First-order scattering theories yield good and reasonable predictions for Ne, Ar and Kr, respectively. For Xe theories also predict significant deviations from statistical weight ratios but there is no agreement between experiment and theory. Surprisingly, the DCS ratios (r') obtained for the ns[3/2]1o, and ns'[1/2]1o levels by experiment and various first-order theories deviate significantly for all rare-gas species. It is also surprising that the fully relativistic first-order theory does not show improved agreement between experiment and theory in the case of Xe. C1 JET PROP LAB,PASADENA,CA 91109. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. RP KHAKOO, MA (reprint author), CALIF STATE UNIV FULLERTON,DEPT PHYS,FULLERTON,CA 92634, USA. NR 35 TC 51 Z9 51 U1 0 U2 8 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD JUL 28 PY 1994 VL 27 IS 14 BP 3159 EP 3174 DI 10.1088/0953-4075/27/14/045 PG 16 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA PA650 UT WOS:A1994PA65000045 ER PT J AU CHAO, BF AF CHAO, BF TI MAN-MADE LAKES AND SEA-LEVEL RISE SO NATURE LA English DT Letter RP CHAO, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 4 TC 18 Z9 20 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 JUL 28 PY 1994 VL 370 IS 6487 BP 258 EP 258 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NZ229 UT WOS:A1994NZ22900041 ER PT J AU YATER, JA KASH, K CHAN, WK RAVI, TS GMITTER, TJ FLOREZ, LT HARBISON, JP AF YATER, JA KASH, K CHAN, WK RAVI, TS GMITTER, TJ FLOREZ, LT HARBISON, JP TI VOLTAGE TUNABLE POTENTIAL WELLS FOR WIRE CONFINEMENT OF EXCITONS SO APPLIED PHYSICS LETTERS LA English DT Article ID GAAS AB We use applied voltage to modulate lateral strain in a quantum well, thereby achieving tunable confinement of excitons. A capacitor structure is fabricated by attaching a flexible film containing a quantum well and a conducting layer to a doped Si substrate patterned with raised ribs. The film conforms to the ribs, creating a potential well for excitons where the quantum well is in tension. The film is pulled toward the substrate through electrostatic force, increasing the confinement. Modulation of strain confinement by over 50% is reported. The effect is reversible with voltage and polarity independent, as expected for electrostatic attraction. C1 DARTMOUTH COLL,HANOVER,NH 03755. CASE WESTERN RESERVE UNIV,DEPT PHYS,CLEVELAND,OH 44106. BELLCORE,RED BANK,NJ 07701. RP YATER, JA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. OI Kash, Kathleen/0000-0002-6126-7302 NR 13 TC 1 Z9 1 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD JUL 25 PY 1994 VL 65 IS 4 BP 460 EP 462 DI 10.1063/1.112332 PG 3 WC Physics, Applied SC Physics GA NY414 UT WOS:A1994NY41400027 ER PT J AU ASKER, JR AF ASKER, JR TI JUPITER COMET IS A SMASH HIT SO AVIATION WEEK & SPACE TECHNOLOGY LA English DT Article RP ASKER, JR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU MCGRAW HILL INC PI NEW YORK PA 1221 AVENUE OF THE AMERICAS, NEW YORK, NY 10020 SN 0005-2175 J9 AVIAT WEEK SPACE TEC JI Aviat. Week Space Technol. PD JUL 25 PY 1994 VL 141 IS 4 BP 20 EP 22 PG 3 WC Engineering, Aerospace SC Engineering GA NY910 UT WOS:A1994NY91000006 ER PT J AU MCKENNA, JT AF MCKENNA, JT TI ASTRONAUTS WRAP-UP 14-DAY RESEARCH FLIGHT SO AVIATION WEEK & SPACE TECHNOLOGY LA English DT Article RP MCKENNA, JT (reprint author), NASA JOHN F KENNEDY SPACE CTR,ORLANDO,FL 32815, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU MCGRAW HILL INC PI NEW YORK PA 1221 AVENUE OF THE AMERICAS, NEW YORK, NY 10020 SN 0005-2175 J9 AVIAT WEEK SPACE TEC JI Aviat. Week Space Technol. PD JUL 25 PY 1994 VL 141 IS 4 BP 23 EP 23 PG 1 WC Engineering, Aerospace SC Engineering GA NY910 UT WOS:A1994NY91000007 ER PT J AU CARLSON, BE LACIS, AA ROSSOW, WB AF CARLSON, BE LACIS, AA ROSSOW, WB TI BELT-ZONE VARIATIONS IN THE JOVIAN CLOUD STRUCTURE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID TROPOSPHERIC GAS-COMPOSITION; NORTH EQUATORIAL BELT; INFRARED OBSERVATIONS; IRIS OBSERVATIONS; WATER-VAPOR; JUPITER; ABUNDANCE; VOYAGER; ATMOSPHERE; PLANETS AB Voyager IRIS observations of Jupiter in the far infrared (180-1200 cm-1) are sensitive to emission originating from pressures less than 2 bars, while the 5-mum (1800-2300 cm-1) observations are primarily sensitive to emission, originating from pressures greater than 2 bars. We use these differences in the location of the peak emission level to constrain the properties of the upper tropospheric cloud structure from the far-infrared observations and then use the 5-mum observations, with the upper tropospheric cloud structure fixed, to constrain the deep cloud structure. The relationship between observed 45- and 5-mum brightness temperatures reveals three distinct regions between +/-25-degrees latitude: North Equatorial Belt hot spots, which are ''hot'' at both 45 and 5 mum; Equatorial Zone spectra, which are ''warm'' at 45 mum and ''cold'' at 5 mum; and North Tropical Zone spectra, which are ''cold'' at both 45 and 5 mum. We find that the hot extreme spectral ensemble is unique to belts, and the cold extreme spectral ensembles are unique to zones, but that all other intermediate spectral ensembles are common to both regions. Analyses of these spectra using an anisotropic multiple scattering radiative transfer model reveal that the primary difference between belts and zones is the increased opacity and vertical extent of clouds in zones relative to their belt counterparts. In addition, we find a shift in the location of the para hydrogen gradient toward lower pressures in zones, with an increase in the ''equilibrated'' cloud-top para fraction. We suggest that all of the variations in gas abundance profiles, temperature, and cloud structure are consistent with the effects of a simple mean circulation and large-scale wave motions. RP NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. RI Lacis, Andrew/D-4658-2012; Carlson, Barbara/D-8319-2012; Rossow, William/F-3138-2015 NR 40 TC 23 Z9 23 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9097 EI 2169-9100 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUL 25 PY 1994 VL 99 IS E7 BP 14623 EP 14658 DI 10.1029/94JE01222 PG 36 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NY861 UT WOS:A1994NY86100002 ER PT J AU SCHULTZ, RA ZUBER, MT AF SCHULTZ, RA ZUBER, MT TI OBSERVATIONS, MODELS, AND MECHANISMS OF FAILURE OF SURFACE ROCKS SURROUNDING PLANETARY SURFACE LOADS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID LITHOSPHERIC STRESS; VALLES MARINERIS; FAULT MECHANICS; VENUS TECTONICS; THARSIS REGION; MARS; DEFORMATION; MAGELLAN; GRAVITY; BASINS AB Geophysical models of flexural stresses in an elastic lithosphere due to an axisymmetric surface load typically predict a transition with increased distance from the center of the load of radial thrust faults to strike-slip faults to concentric normal faults. These model predictions are in conflict with the absence of annular zones of strike-slip faults around prominent loads such as lunar maria, Martian volcanoes, and the Martian Tharsis rise. We suggest that this paradox arises from difficulties in relating failure criteria for brittle rocks to the stress models. Indications that model stresses are inappropriate for use in fault-type prediction include (1) tensile principal stresses larger than realistic values of rock tensile strength, and/or (2) stress differences significantly larger than those allowed by rock-strength criteria. Predictions of surface faulting that are consistent with observations can be obtained instead by using tensile and shear failure criteria, along with calculated stress differences and trajectories, with model stress states not greatly in excess of the maximum allowed by rock fracture criteria. C1 NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771. JOHNS HOPKINS UNIV,DEPT EARTH & PLANETARY SCI,BALTIMORE,MD 21218. RP SCHULTZ, RA (reprint author), UNIV NEVADA,MACKAY SCH MINES 172,DEPT GEOL SCI,GEOMECH ROCK FRACTURE GRP,RENO,NV 89557, USA. RI Schultz, Richard/J-4015-2015 OI Schultz, Richard/0000-0003-3198-5263 NR 86 TC 32 Z9 32 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD JUL 25 PY 1994 VL 99 IS E7 BP 14691 EP 14702 DI 10.1029/94JE01140 PG 12 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NY861 UT WOS:A1994NY86100005 ER PT J AU FISCHBACH, E KLOOR, H LANGEL, RA LUI, ATY PEREDO, M AF FISCHBACH, E KLOOR, H LANGEL, RA LUI, ATY PEREDO, M TI NEW GEOMAGNETIC LIMITS ON THE PHOTON MASS AND ON LONG-RANGE FORCES COEXISTING WITH ELECTROMAGNETISM SO PHYSICAL REVIEW LETTERS LA English DT Article ID MAGNETIC-FIELD; MODELS AB A new geomagnetic limit on the photon mass m(gamma) is derived from an analysis of satellite measurements of the Earth's magnetic field H over arrow pointing right. The primary effect of a nonzero photon mass is to generate an additional contribution to H over arrow pointing right resembling that from an external source. We find m(gamma) less-than-or-equal-to 8 x 10(-16) eV/c2 = 1 x 10(-48) g = 4 x 10(-9) m-1. The same data are also used to set new limits on long-range fields coexisting with electromagnetism. C1 PURDUE UNIV, DEPT PHYS, W LAFAYETTE, IN 47907 USA. PURDUE UNIV, DEPT EARTH & ATMOSPHER SCI, W LAFAYETTE, IN 47907 USA. JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD 20723 USA. HUGHES STX CORP, LANHAM, MD 20706 USA. NASA, GODDARD SPACE FLIGHT CTR, GEODYNAM BRANCH, GREENBELT, MD 20771 USA. RP FISCHBACH, E (reprint author), PURDUE UNIV, DEPT PHYS, W LAFAYETTE, IN 47907 USA. NR 21 TC 37 Z9 39 U1 0 U2 1 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD JUL 25 PY 1994 VL 73 IS 4 BP 514 EP 517 DI 10.1103/PhysRevLett.73.514 PG 4 WC Physics, Multidisciplinary SC Physics GA NZ237 UT WOS:A1994NZ23700002 ER PT J AU GLICKSMAN, ME KOSS, MB WINSA, EA AF GLICKSMAN, ME KOSS, MB WINSA, EA TI DENDRITIC GROWTH VELOCITIES IN MICROGRAVITY SO PHYSICAL REVIEW LETTERS LA English DT Article AB We measured dendritic tip velocities in pure succinonitrile (SCN) in microgravity, using a sequence of telemetered binary images sent to Earth from the space shuttle Columbia (STS-62). Growth velocities were measured as a function of the supercooling over the range 0.05-1.5 K. Microgravity observations show that buoyancy-induced convection alters the growth kinetics of SCN dendrites at supercoolings as high as 1.3 K. Also, the dendrite velocity data measured under microgravity agree well with the Ivantsov paraboloidal diffusion solution when coupled to a scaling constant of sigma* = 0.0157. C1 RENSSELAER POLYTECH INST, DEPT MAT ENGN, TROY, NY 12180 USA. NASA, LEWIS RES CTR, DIV SPACE EXPT, CLEVELAND, OH 44135 USA. RP GLICKSMAN, ME (reprint author), RENSSELAER POLYTECH INST, DEPT MAT ENGN, TROY, NY 12180 USA. OI Glicksman, Martin/0000-0002-2675-2759 NR 11 TC 163 Z9 163 U1 1 U2 13 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD JUL 25 PY 1994 VL 73 IS 4 BP 573 EP 576 DI 10.1103/PhysRevLett.73.573 PG 4 WC Physics, Multidisciplinary SC Physics GA NZ237 UT WOS:A1994NZ23700017 ER PT J AU DICKEY, JO BENDER, PL FALLER, JE NEWHALL, XX RICKLEFS, RL RIES, JG SHELUS, PJ VEILLET, C WHIPPLE, AL WIANT, JR WILLIAMS, JG YODER, CF AF DICKEY, JO BENDER, PL FALLER, JE NEWHALL, XX RICKLEFS, RL RIES, JG SHELUS, PJ VEILLET, C WHIPPLE, AL WIANT, JR WILLIAMS, JG YODER, CF TI LUNAR LASER RANGING - A CONTINUING LEGACY OF THE APOLLO PROGRAM SO SCIENCE LA English DT Article ID ATMOSPHERIC ANGULAR-MOMENTUM; EARTH-MOON SYSTEM; FORCED NUTATIONS; EQUIVALENCE PRINCIPLE; RADIO INTERFEROMETRY; PRECESSION; EPHEMERIS; ROTATION; GRAVITY; LENGTH AB On 21 July 7 1969, during the first manned lunar mission, Apollo 11, the first retroreflector array was placed on the moon, enabling highly accurate measurements of the Earth-moon separation by means of laser ranging. Lunar laser ranging (LLR) turns the Earth-moon system into a laboratory for a broad range of investigations, including astronomy, lunar science, gravitational physics, geodesy, and geodynamics. Contributions from LLR include the three-orders-of-magnitude improvement in accuracy in the lunar ephemeris, a several-orders-of-magnitude improvement in the measurement of the variations in the moon's rotation, and the verification of the principle of equivalence for massive bodies with unprecedented accuracy. Lunar laser ranging analysis has provided measurements of the Earth's precession, the moon's tidal acceleration, and lunar rotational dissipation. These scientific results, current technological developments, and prospects for the future are discussed here. C1 UNIV COLORADO,NATL INST STAND & TECHNOL,JOINT INST LAB ASTROPHYS,BOULDER,CO 80309. UNIV TEXAS,MCDONALD OBSERV ASTRON,AUSTIN,TX 78712. MCDONALD OBSERV,FT DAVIS,TX 79734. CERGA,OCA,F-06130 GRASSE,FRANCE. RP DICKEY, JO (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 96 TC 378 Z9 396 U1 5 U2 29 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUL 22 PY 1994 VL 265 IS 5171 BP 482 EP 490 DI 10.1126/science.265.5171.482 PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NY216 UT WOS:A1994NY21600019 PM 17781305 ER PT J AU ROSENZWEIG, C AF ROSENZWEIG, C TI CLIMATE - MAIZE SUFFERS A SEA-CHANGE SO NATURE LA English DT Editorial Material ID NINO SOUTHERN OSCILLATION C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP ROSENZWEIG, C (reprint author), COLUMBIA UNIV,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 6 TC 15 Z9 15 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 JUL 21 PY 1994 VL 370 IS 6486 BP 175 EP 176 DI 10.1038/370175a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NX971 UT WOS:A1994NX97100024 ER PT J AU SPINHIRNE, JD NAKAJIMA, T AF SPINHIRNE, JD NAKAJIMA, T TI GLORY OF CLOUDS IN THE NEAR-INFRARED SO APPLIED OPTICS LA English DT Article ID STRATOCUMULUS; RADIOMETER; FIRE; ATMOSPHERES; PARAMETERS; WATER AB Spectrally resolved visible and infrared images of marine stratus clouds were acquired from the NASA ER-2 high-altitude aircraft during the 1987 First International Cloud Climatology Program Regional Experiment. The images were obtained by cross-track scanning radiometers. Data images at near-infrared wavelengths show frequent and readily apparent brightness features that are due to glory single scattering. The observations and subsequent analysis by radiative transfer calculations show that the glory is a significant feature of near-infrared solar reflectance from water clouds. Glory observations and calculations based on in-cloud microphysics measurements agree well. The most dramatic difference from the visible glory is that the scattering angles are significantly larger in the near infrared. The glory is also apparently more distinct in the near infrared than in the visible, as scattering size parameters are in a range that effectively produces a glory feature, and also there is less obscuration by multiple-scattering reflectance because of absorption of radiation by droplets in the near infrared. For both the visible and the near infrared, the principal factors that wash out the glory are dispersion and, to a lesser degree, the effective radius of the cloud droplet-size distribution. The obscuration by multiple scattering in optically thick clouds is secondary. Rather than being a novelty, glory observations would be an accurate and unambiguous technique to sense the droplet size of water clouds remotely. C1 UNIV TOKYO, CTR CLIMATE SYST RES, MEGURO KU, TOKYO 153, JAPAN. RP SPINHIRNE, JD (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 917, GREENBELT, MD 20771 USA. RI Nakajima, Teruyuki/H-2370-2013 OI Nakajima, Teruyuki/0000-0002-9042-504X NR 14 TC 21 Z9 21 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 1994 VL 33 IS 21 BP 4652 EP + PG 0 WC Optics SC Optics GA PB632 UT WOS:A1994PB63200017 PM 20935835 ER PT J AU TOTH, RA AF TOTH, RA TI EXTENSIVE MEASUREMENTS OF (H2O)-O-16 LINE FREQUENCIES AND STRENGTHS - 5750 TO 7965 CM(-1) SO APPLIED OPTICS LA English DT Article ID TRANSITION FREQUENCIES; BANDS; POSITIONS; SPECTRUM; REGION; CM-1; H2O AB High-resolution spectra of (H2O)-O-16 vapor covering the region from 5750 to 7965 cm-1 were used to determine experimental values of line positions and strengths of over 3750 vibration-rotation transitions in the (110)-(000), (011)-(000), (040)-(000), (120)-(000), (021)-(000), (200)-(000), (101)-(000), (002)-(000), (031)-(010), (210)-(010) and (111)-(010) bands from which rotational energy levels in the (040), (120), (021), (200), (101) and (002) vibrational states were obtained. The line strengths and frequencies reported here are considered to be a marked improvement over the values listed in the 1986 edition of the HITRAN database, and a preliminarly listing from this work has been included in the 1993 HITRAN edition. RP TOTH, RA (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. NR 14 TC 138 Z9 142 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 1994 VL 33 IS 21 BP 4851 EP + PG 0 WC Optics SC Optics GA PB632 UT WOS:A1994PB63200044 PM 20935862 ER PT J AU TOTH, RA AF TOTH, RA TI TRANSITION FREQUENCIES AND STRENGTHS OF (H2O)-O-17 AND (H2O)-O-18 - 6600 TO 7640 CM(-1) SO APPLIED OPTICS LA English DT Article ID REGION AB High-resolution spectra of O-17- and O-18-enriched water-vapor samples have been recorded with a Fourier transform spectrometer covering the region between 6600 and 7640 cm-1. Experimental values of line positions and strengths of 1807 absorptions in the (120)-(000), (021)-(000), (200)-(000), (101)-(000), (002)-(000), bands of the two isotopic species were derived from the spectra. The analysis included the determination of accurate rotational levels belonging to the (120), (021), (200), (101), and (002) vibrational states of (H2O)-O-17 and (H2O)-O-18. RP TOTH, RA (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. NR 7 TC 35 Z9 36 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 20 PY 1994 VL 33 IS 21 BP 4868 EP + PG 0 WC Optics SC Optics GA PB632 UT WOS:A1994PB63200045 PM 20935863 ER PT J AU NETZER, H KAZANAS, D WILLS, BJ WILLS, D HAN, MS BROTHERTON, MS BALDWIN, JA FERLAND, GJ BROWNE, IWA AF NETZER, H KAZANAS, D WILLS, BJ WILLS, D HAN, MS BROTHERTON, MS BALDWIN, JA FERLAND, GJ BROWNE, IWA TI THE OPTICAL-ULTRAVIOLET-GAMMA-RAY SPECTRUM OF 3C 279 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; GAMMA RAYS, OBSERVATIONS; QUASARS, INDIVIDUAL (3C 279); RADIATION MECHANISMS, NONTHERMAL; ULTRAVIOLET, GALAXIES ID ACTIVE GALACTIC NUCLEI; X-RAY; QUASAR 3C-279; OUTBURST AB We have obtained spectroscopy of the violently variable quasar 3C 279, simultaneous with gamma-ray observations, in 1992 April. Our combined optical (McDonald Observatory and CTIO) and ultraviolet (HST) observations, made when the source was faint, show a very steep power-law continuum (F(nu) is-proportional-to nu-1.95), and strong broad emission lines. This is the first time that the broad ultraviolet lines of this object have been measured, and we note several unusual properties of the spectrum. In particular, the profiles of C IV lambda1549 and Mg II lambda2798 are asymmetric, with very strong red wings, in contrast to the symmetric profile of Lyalpha C III] lambda1909, and possibly Hbeta. The observed asymmetry cannot be explained by a simple outflow associated with the eruption of the source. In addition, the C IV lambda1549/Lyalpha and C III] lambda1909/Lyalpha line intensity ratios are the largest we have observed in our HST sample of more than 30 radio-loud quasars, even though the C III] lambda1909/C IV lambda1549 ratio is quite typical. 3C 279 was observed in the gamma-ray region by EGRET at the same time as our optical-ultraviolet observations. The extrapolated ultraviolet continuum falls nine orders of magnitude below the gamma-ray point and we show that this, combined with the optical UV continuum slope, is enough to rule out several synchrotron-self-Compton models suggested to explain the multiwavelength spectra of blazars. blazars. C1 TEL AVIV UNIV,WISE OBSERV,BEVERLY & RAYMOND SACKLER FAC EXACT SCI,IL-69978 TEL AVIV,ISRAEL. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. CERRO TOLOLO INTERAMER OBSERV,LA SERENA,CHILE. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. JODRELL BANK,CHESHIRE SK11 9DL,ENGLAND. UNIV KENTUCKY,DEPT PHYS & ASTRON,LEXINGTON,KY 40506. RP NETZER, H (reprint author), TEL AVIV UNIV,SCH PHYS & ASTRON,IL-69978 TEL AVIV,ISRAEL. OI Ferland, Gary/0000-0003-4503-6333 NR 29 TC 17 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 JUL 20 PY 1994 VL 430 IS 1 BP 191 EP 195 DI 10.1086/174393 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW513 UT WOS:A1994NW51300016 ER PT J AU XIE, TL GOLDSMITH, PF AF XIE, TL GOLDSMITH, PF TI THE GIANT MOLECULAR CLOUD MONOCEROS R2 .1. SHELL STRUCTURE SO ASTROPHYSICAL JOURNAL LA English DT Article DE H II REGIONS; ISM, INDIVIDUAL (MONOCEROS R2); ISM, MOLECULES; ISM; STRUCTURE; REFLECTIONS NEBULAE ID COMETARY GLOBULES; STAR FORMATION; OUTFLOW; NEBULA AB We have obtained a 45'' resolution, Nyquist-sampled map in CO J = 1-0 covering approximately a 3-degrees x 3-degrees region of the giant molecular cloud Monoceros R2. The map consists of 167,000 spectra observed with the 15 element focal-plane array system on the FCRAO 14 m telescope. The data reveal that the large-scale structure of Mon R2 is dominated by a approximately 30 pc diameter largely hemispherical shell containing approximately 4 x 10(4) M. of molecular material and expanding at approximately 3-4 km s-1 with symmetry axis roughly along the line of sight. The dynamical timescale of the shell is estimated to be approximately 4 x 10(6) yr, which is consistent with the age of main-sequence stars powering the clusters of reflection nebulae in this region. There is no evidence for a redshifted shell on the far side of the interior ''bubble'' which is largely devoid of molecular material. Distortions of the shell are obvious, suggesting inhomogeneity of the cloud and possible presence of a magnetic field prior to its formation. Dense clumps in Mon R2, including the main core and the GGD 12-15 core, appear to be condensations located on the large shell. The reflection nebulae with their illuminating stars as well as embedded IRAS sources suggest that triggered star formation has taken place over a large part of the Mon R2 shell. C1 JET PROP LAB,PASADENA,CA 91109. RP XIE, TL (reprint author), UNIV MASSACHUSETTS,DEPT PHYS & ASTRON,FIVE COLL RADIO ASTRON OBSERV,AMHERST,MA 01003, USA. RI Goldsmith, Paul/H-3159-2016 NR 29 TC 17 Z9 17 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1994 VL 430 IS 1 BP 252 EP 255 DI 10.1086/174399 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW513 UT WOS:A1994NW51300022 ER PT J AU THOMAS, D SCHRAMM, DN OLIVE, KA MATHEWS, GJ MEYER, BS FIELDS, BD AF THOMAS, D SCHRAMM, DN OLIVE, KA MATHEWS, GJ MEYER, BS FIELDS, BD TI PRODUCTION OF LITHIUM, BERYLLIUM, AND BORON FROM BARYON INHOMOGENEOUS PRIMORDIAL NUCLEOSYNTHESIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES; STARS, POPULATION-II ID HADRON PHASE-TRANSITION; BIG-BANG NUCLEOSYNTHESIS; METAL-DEFICIENT DWARFS; HALO-STARS; NEUTRON DIFFUSION; EARLY UNIVERSE; NUMBER FLUCTUATIONS; EARLY GALAXY; ABUNDANCE; EVOLUTION AB We investigate the possibility that inhomogeneous nucleosynthesis may eventually be used to explain the abundances of Li-6, Be-9, and B in Population II stars. The present work differs from previous studies in that we have used a more extensive reaction network. It is demonstrated that in the simplest scenario the abundances of the light elements with A less-than-or-equal-to 7 constrain the separation of inhomogeneities to sufficiently small scales that the model is indistinguishable from homogeneous nucleosynthesis and that the abundances of Li-6, Be-9, and B are then below observations by several orders of magnitude. This conclusion does not depend on the Li-7 constraint. We also examine alternative scenarios which involve a post-nucleosynthesis reprocessing of the light elements to reproduce the observed abundances of Li and B, while allowing for a somewhat higher baryon density (still well below the cosmological critical density). Future B/H measurements may be able to exclude even this exotic scenario and further restrict primordial nucleosynthesis to approach the homogeneous model conclusions. C1 CLEMSON UNIV,DEPT PHYS & ASTRON,CLEMSON,SC 29634. UNIV MINNESOTA,SCH PHYS & ASTRON,MINNEAPOLIS,MN 55455. LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. NASA,FERMILAB ASTROPHYS CTR,FNAL,BATAVIA,IL 60510. RP THOMAS, D (reprint author), UNIV CHICAGO,CHICAGO,IL 60637, USA. NR 61 TC 46 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 JUL 20 PY 1994 VL 430 IS 1 BP 291 EP 299 DI 10.1086/174403 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW513 UT WOS:A1994NW51300026 ER PT J AU GOEBEL, JH BREGMAN, JD WITTEBORN, FC AF GOEBEL, JH BREGMAN, JD WITTEBORN, FC TI A 7 MICRON DUST EMISSION FEATURE IN OXYGEN-RICH CIRCUMSTELLAR SHELLS SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; DUST, EXTINCTION; INFRARED, STARS; STARS, INDIVIDUAL (R-CASSEIOPIAE, ALPHA-ORIONIS) ID LOW-RESOLUTION SPECTRA; M-MIRA VARIABLES; INFRARED TRANSMISSION SPECTRA; IRAS LRS OBSERVATIONS; H-II REGIONS; SILICATE EMISSION; RADIATIVE-TRANSFER; CARBON STARS; SUPER-GIANTS; PARTICLES AB New 4 to 8 mum infrared spectroscopic observations of two oxygen-rich stars are presented and combined with IRAS LRS data to span the 4 to 24 mum wavelength range. In the 4 to 8 mum wavelength range, we observe a 7.15 mum (1400 cm-1) emission feature. The new feature at 7.15 mum is not uniquely correlated with any of the sharply defined 10, 11, 13.1, and 19.7 mum emission features that are known to be present in this class of circumstellar shells, but it does appear to be correlated with the spectrally broad dust emission in the 10 to 20 mum spectral region. The feature has not been reported previously in any other astronomical environment. A reinterpretation of prior 4 to 8 mum spectroscopy of alpha Ori and R Cas reveals the presence of the 7.15 mum emission in alpha Ori and possibly in R Cas. The spectrally narrow 19.7 mum emission, that is distinctly different than the relatively broad silicate 18 mum emission feature in oxygen-rich dust shells, is also observed to be present in the LRS spectrum of SAO 197549. The implication of these observations is that a universal astronomical silicate does not exist in oxygen-rich circumstellar shells. This variety is analogous to that observed in interplanetary dust particles and may indicate an intimate relation between the two classes of condensates. C1 NASA,AMES RES CTR,ASTROPHYS BRANCH,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP GOEBEL, JH (reprint author), NASA,AMES RES CTR,TECHNOL DEV BRANCH,DIV SPACE PROJECTS,MOFFETT FIELD,CA 94035, USA. NR 54 TC 12 Z9 12 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1994 VL 430 IS 1 BP 317 EP 322 DI 10.1086/174406 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW513 UT WOS:A1994NW51300029 ER PT J AU MITCHELL, KJ DENNISON, B CONDON, JJ ALTSCHULER, DR PAYNE, HE ODELL, SL BRODERICK, JJ AF MITCHELL, KJ DENNISON, B CONDON, JJ ALTSCHULER, DR PAYNE, HE ODELL, SL BRODERICK, JJ TI RESULTS OF A 5-YEAR PROGRAM OF MULTIFREQUENCY MONITORING OF LOW-FREQUENCY VARIABLE RADIO-SOURCES SO ASTROPHYSICAL JOURNAL LA English DT Meeting Abstract C1 VIRGINIA POLYTECH INST & STATE UNIV,CTR STOCHASTIC PROC SCI & ENGN,BLACKSBURG,VA 24061. UNIV PUERTO RICO,NATL ASTRON & IONOSPHERE CTR,RIO PIEDRAS,PR 00931. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. VIRGINIA POLYTECH INST & STATE UNIV,DEPT PHYS,BLACKSBURG,VA 24061. NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV PUERTO RICO,FAC NAT SCI,DEPT PHYS,RIO PIEDRAS,PR 00931. NR 0 TC 0 Z9 0 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1994 VL 430 IS 1 BP 440 EP 440 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW513 UT WOS:A1994NW51300045 ER PT J AU HYUNG, S ALLER, LH FEIBELMAN, WA AF HYUNG, S ALLER, LH FEIBELMAN, WA TI THE SPECTRUM OF THE VARIABLE PLANETARY-NEBULA IC-4997 SO ASTROPHYSICAL JOURNAL LA English DT Meeting Abstract C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. NR 0 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1994 VL 430 IS 1 BP 441 EP 441 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW513 UT WOS:A1994NW51300047 ER PT J AU KAITCHUCK, RH SCHLEGEL, EM HONEYCUTT, RK HORNE, K MARSH, TR WHITE, JC MANSPERGER, CS AF KAITCHUCK, RH SCHLEGEL, EM HONEYCUTT, RK HORNE, K MARSH, TR WHITE, JC MANSPERGER, CS TI AN ATLAS OF DOPPLER EMISSION-LIKE TOMOGRAPHY OF CATACLYSMIC VARIABLE-STARS SO ASTROPHYSICAL JOURNAL LA English DT Meeting Abstract C1 BALL STATE UNIV,DEPT PHYS & ASTRON,MUNCIE,IN 47306. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. INDIANA UNIV,DEPT ASTRON,BLOOMINGTON,IN 47401. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV OXFORD,DEPT ASTROPHYS,OXFORD,ENGLAND. NR 0 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1994 VL 430 IS 1 BP 442 EP 442 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW513 UT WOS:A1994NW51300049 ER PT J AU CLARKE, JT JAFFEL, LB VIDALMADJAR, A GLADSTONE, GR WAITE, JH PRANGE, R GERARD, JC AJELLO, J JAMES, G AF CLARKE, JT JAFFEL, LB VIDALMADJAR, A GLADSTONE, GR WAITE, JH PRANGE, R GERARD, JC AJELLO, J JAMES, G TI HUBBLE-SPACE-TELESCOPE GODDARD HIGH-RESOLUTION SPECTROGRAPH H2 ROTATIONAL SPECTRA OF JUPITER AURORA SO ASTROPHYSICAL JOURNAL LA English DT Article DE PLANETS AND SATELLITES, GENERAL; PLANETS AND SATELLITES, INDIVIDUAL (JUPITER) ID ELECTRON-IMPACT; UV AURORA; EMISSION; H-2 AB We have observed the emission spectrum from Jupiter's north auroral atmosphere with 0.57 angstrom spectral resolution over 1204-1241 angstrom. Bright emissions have been detected from 50-degrees to 60-degrees latitude at locations consistent with 6 to 30 R(J) auroral ovals, with much fainter emissions away from the auroral ovals. The emission spectrum is well fitted by both laboratory spectra and theoretical models of optically thin electron excited H-2, with added Doppler-broadened Lyalpha emission. The observed Lyalpha emission wings extend more than 1 angstrom from line center and appear correlated in strength with the H-2 brightness. Individual rotational lines in the H-2 Werner band system are resolved, allowing a determination of the H-2 rotational temperature at the altitude of the emission. We derive best-fit temperatures from 400-450 to 700-750 K, with the auroral emission layer temperature changing either across the auroral oval or over several days' time. These observations demonstrate for the first time the ability to measure the observed rapid H-2 temperature variations across Jupiter's auroral atmosphere. C1 UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. SW RES INST,SAN ANTONIO,TX 78284. JET PROP LAB,PASADENA,CA 91109. UNIV PARIS 11,INST ASTROPHYS SPATIALE,F-91405 ORSAY,FRANCE. INST ASTROPHYS,F-75014 PARIS,FRANCE. RP CLARKE, JT (reprint author), UNIV MICHIGAN,DEPT AOSS,ANN ARBOR,MI 48109, USA. RI Clarke, John/C-8644-2013 NR 18 TC 43 Z9 43 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 JUL 20 PY 1994 VL 430 IS 1 BP L73 EP L76 DI 10.1086/187441 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW514 UT WOS:A1994NW51400019 ER PT J AU SALAMON, MH STECKER, FW AF SALAMON, MH STECKER, FW TI THE BLAZAR GAMMA-RAY LUMINOSITY FUNCTION AND THE DIFFUSE EXTRAGALACTIC GAMMA-RAY BACKGROUND SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; GAMMA RAYS, THEORY; QUASARS, GENERAL ID ACTIVE GALACTIC NUCLEI; RADIO-SOURCES; RADIATION; ORIGIN AB We have used the data from the new EGRET catalog on ''grazars'' (blazars which are observed to be high-energy gamma-ray sources), together with radio data, to construct a new relation between radio and gamma-ray luminosity for these sources. Using this relation to construct a grazar gamma-ray luminosity function, we then calculate the contribution of unresolved grazars to the cosmic gamma-ray background radiation. We derive the energy spectrum of this background component above 100 MeV and the angular fluctuations in this background implied by our model. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP SALAMON, MH (reprint author), UNIV UTAH,INST HIGH ENERGY ASTROPHYS,DEPT PHYS,SALT LAKE CITY,UT 84112, USA. RI Stecker, Floyd/D-3169-2012 NR 20 TC 64 Z9 64 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 20 PY 1994 VL 430 IS 1 BP L21 EP L24 DI 10.1086/187428 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW514 UT WOS:A1994NW51400006 ER PT J AU MATTEI, S VETRELLA, S MOCCIA, A LANE, AL PIERI, DC ABRAMS, MJ BIANCHI, R AF MATTEI, S VETRELLA, S MOCCIA, A LANE, AL PIERI, DC ABRAMS, MJ BIANCHI, R TI POTENTIAL OBSERVATIONS WITH EURECA/VEXUVIO IMAGING SPECTROMETER SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID VOLCANOS; ETNA AB Despite its geological importance, the Earth's volcanic activity has only recently been studied as a global system, with the advent of sophisticated airborne and spaceborne remote sensing systems that safely and economically provide global access at will. Particularly relevant to this approach are global studies of the effects on weather and climate caused by volcanic solid/gaseous products and thermal flux into the environment. To study such time-varying phenomena, observations of volcanic emissions spectral response, acquired simultaneously at a variety of wavelengths from ultra-violet to infra-red, could yield relevant information on the compositions and concentrations of environmentally important components, such as volcanically generated sulphur compounds (e.g., SO2, H2SO4), and on volcanoes thermal behaviour. For this purpose, a multi-band imaging spectrometer, dedicated to volcanological observations (VEXUVIO, Visible EXplorer Ultra Violet Infra-red Observer) has been designed to be flown on-board EURECA (EUropean REtrievable CArrier) spacecraft, to be launched by the European Space Agency on the NASA Space Shuttle in 1996. In order to analyse potential observation scenarios with this sensor, volcanoes active during 1991 were studied using a computer code to simulate VEXUVIO capabilities on-board EURECA. Some parameters, representative of the sensor viewing geometry and of the volcanoes observation conditions, are exploited, and several plots are reported, shown their values during the six-months nominal EURECA mission. Despite the limited science objectives of EURECA program and a tightly constrained operational environment, our simulation demonstrates that a reasonable program of volcanologically interesting time-series observations can be carried out during the planned six-months lifetime of the EURECA mission. C1 UNIV NAPLES,FAC ENGN,I-80125 NAPLES,ITALY. JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. CNR,I-00044 FRASCATI,ITALY. RP MATTEI, S (reprint author), CONSORTIUM RES ADV REMOTE SENSING SYST,P LE TECCHIO 80,I-80125 NAPLES,ITALY. NR 26 TC 1 Z9 1 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 20 PY 1994 VL 15 IS 11 BP 2175 EP 2192 PG 18 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PD650 UT WOS:A1994PD65000004 ER PT J AU LEE, JS GRUNES, MR KWOK, R AF LEE, JS GRUNES, MR KWOK, R TI CLASSIFICATION OF MULTI-LOOK POLARIMETRIC SAR IMAGERY-BASED ON COMPLEX WISHART DISTRIBUTION SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB Multi-look polarimetric SAR (synthetic aperture radar) data can be represented either in Mueller matrix form or in complex covariance matrix form. The latter has a complex Wishart distribution. A maximum likelihood classifier to segment polarimetric SAR data according to terrain types has been developed based on the Wishart distribution. This algorithm can also be applied to multi-frequency multi-look polarimetric SAR data, as well as to SAR data containing only intensity information. A procedure is then developed for unsupervised classification. The classification error is assessed by using Monte Carlo simulation of multi-look polarimetric SAR data, owing to the lack of ground truth for each pixel. Comparisons of classification errors using the training sets and single-look data are also made. Applications of this algorithm are demonstrated with NASA/JPL P-, L- and C-band polarimetric SAR data. C1 JET PROP LAB,PASADENA,CA 91109. RP LEE, JS (reprint author), USN,RES LAB,DIV REMOTE SENSING,CODE 7230,WASHINGTON,DC 20375, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 17 TC 304 Z9 350 U1 2 U2 32 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 20 PY 1994 VL 15 IS 11 BP 2299 EP 2311 PG 13 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PD650 UT WOS:A1994PD65000011 ER PT J AU LIN, DS WOOD, EF BEVEN, K SAATCHI, S AF LIN, DS WOOD, EF BEVEN, K SAATCHI, S TI SOIL-MOISTURE ESTIMATION OVER GRASS-COVERED AREAS USING AIRSAR SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID MODELS AB An empirical study of the relation between the AIRSAR's signals and land surface parameters is conducted using data collected during MAC-EUROPE'91. General additive regression models are fitted to the data simulated from a calibrated microwave backscattering model. A comparison between the model predictions and field observations indicates that the regression models are good predictors to the AIRSAR's signals over the grass-covered areas. Based on the regression relationships, a soil moisture retrieval algorithm combining the L-band multi-polarization AIRSAR data is proposed and used to create spatial soil moisture maps of the Slapton Wood catchment. C1 UNIV LANCASTER,CTR RES ENVIRONM SYST,LANCASTER LA1 4YL,ENGLAND. CALTECH,JET PROPULS LAB,NASA,PASADENA,CA 91104. RP LIN, DS (reprint author), PRINCETON UNIV,DEPT CIVIL ENGN & OPERAT RES,PRINCETON,NJ 08544, USA. RI Beven, Keith/F-8707-2011; OI Wood, Eric/0000-0001-7037-9675 NR 20 TC 32 Z9 32 U1 0 U2 3 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 20 PY 1994 VL 15 IS 11 BP 2323 EP 2343 PG 21 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PD650 UT WOS:A1994PD65000013 ER PT J AU KOSHAK, WJ SOLAKIEWICZ, RJ PHANORD, DD BLAKESLEE, RJ AF KOSHAK, WJ SOLAKIEWICZ, RJ PHANORD, DD BLAKESLEE, RJ TI DIFFUSION-MODEL FOR LIGHTNING RADIATIVE-TRANSFER SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID FINITE CLOUDS; SATELLITE; SCATTERING; THUNDERSTORMS AB A one-speed Boltzmann transport theory, with diffusion approximations, is applied to study the radiative transfer properties of lightning in optically thick thunderclouds. Near-infrared (lambda = 0.7774 mum) photons associated with a prominent oxygen emission triplet in the lighting spectrum are considered. Transient and spatially complex lightning radiation sources are placed inside a rectangular parallelepiped thundercloud geometry and the effects of multiple scattering are studied. The cloud is assumed to be composed of a homogeneous collection of identical spherical water droplets, each droplet a nearly conservative, anisotropic scatterer. Conceptually, we treat the thundercloud like a nuclear reactor, with photons replaced by neutrons, and utilize standard one-speed neutron diffusion techniques common in nuclear reactor analyses. Valid analytic results for the intensity distribution (expanded in spherical harmonics) are obtained for regions sufficiently far from sources. Model estimates of the arrival-time delay and pulse width broadening of lightning signals radiated from within the cloud are determined and the results are, in good agreement with both experimental data and previous Monte Carlo estimates. Additional model studies of this kind will be used to study the general information content of cloud top lightning radiation signatures. C1 CHICAGO STATE UNIV, CHICAGO, IL 60628 USA. UNIV ALABAMA, DEPT MATH SCI, HUNTSVILLE, AL 35899 USA. RP KOSHAK, WJ (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. NR 47 TC 28 Z9 29 U1 1 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 JUL 20 PY 1994 VL 99 IS D7 BP 14361 EP 14371 DI 10.1029/94JD00022 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NY396 UT WOS:A1994NY39600002 ER PT J AU SODUPE, M BAUSCHLICHER, CW AF SODUPE, M BAUSCHLICHER, CW TI A STUDY OF THE GROUND AND LOW-LYING STATES OF MGC2H2+ AND MGC2H4+ SO CHEMICAL PHYSICS LA English DT Article ID GAUSSIAN-BASIS SETS; MOLECULAR WAVE-FUNCTIONS; METAL POSITIVE-IONS; ANO BASIS-SETS; 2ND ROW ATOMS; PHOTODISSOCIATION SPECTROSCOPY; INFRARED INTENSITIES; FORCE FIELD; ETHYLENE; ACETYLENE AB The geometries and vibrational frequencies are reported for the ground and low-lying states of MgC2H2+ and MgC2H2+. The bonding in the X 2A1 ground state and in the B-2(1) and (2)2A1 excited states is mainly electrostatic. For both ligands, the B-2(1) state is more strongly bound (computed relative to its own asymptote) than the ground state, because the Mg out-of-plane 3p orbital has a smaller overlap and hence a smaller repulsion with the ligand than does the Mg 3s orbital. In the B-2(2) excited state, Mg+ inserts into the ligand pi bond, which leads to a much larger binding energy than that of the ground state or the B-2(1) state. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP SODUPE, M (reprint author), UNIV AUTONOMA BARCELONA, DEPT QUIM, UNITAT QUIM FIS, E-08193 BARCELONA, SPAIN. RI Sodupe, Mariona/E-9352-2013 OI Sodupe, Mariona/0000-0003-0276-0524 NR 40 TC 30 Z9 30 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD JUL 15 PY 1994 VL 185 IS 2 BP 163 EP 171 DI 10.1016/0301-0104(94)00122-7 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NY545 UT WOS:A1994NY54500002 ER PT J AU CHEN, JS GUZIK, TG SANG, YM WEFEL, JP COOPER, JF AF CHEN, JS GUZIK, TG SANG, YM WEFEL, JP COOPER, JF TI ENERGETIC HELIUM PARTICLES TRAPPED IN THE MAGNETOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RADIATION AB High energy (approximately 40-100 MeV/nucleon). geomagnetically trapped helium nuclei have been measured, for the first time, by the ONR-604 instrument during the 1990/1991 CRRES mission. The helium events observed at L < 2.3 have a pitch angle distribution peaking perpendicular to the local magnetic field and are contained in peaks located at L = 1.2 and 1.9. The events in each peak can be characterized by power law energy spectra with indices of 10.0+/-0.7 for L = 1.9-2.3 and 6.8+/-1.0 for L = 1.15-1.3, before the large storm of 24 March 1991. CRRES was active during solar maximum when the anomalous component is excluded from the inner heliosphere, making it unlikely that the observed events derived from the anomalous component. The trapped helium counting rates decrease gradually with time indicating that these high energy ions were not injected by flares during the 1990/91 mission. Flare injection prior to mid-1990 may account for the highest energy particles, while solar wind injection during magnetic storms and subsequent acceleration could account for the helium at lower energies. C1 HUGHES STX CORP,NATL SPACE SCI DATA CTR,NASA,GSFC,GREENBELT,MD 20771. RP CHEN, JS (reprint author), LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803, USA. RI Cooper, John/D-4709-2012 NR 25 TC 14 Z9 14 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 15 PY 1994 VL 21 IS 15 BP 1583 EP 1586 DI 10.1029/94GL01359 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NX648 UT WOS:A1994NX64800004 ER PT J AU TABAZADEH, A TURCO, RP DRDLA, K JACOBSON, MZ TOON, OB AF TABAZADEH, A TURCO, RP DRDLA, K JACOBSON, MZ TOON, OB TI A STUDY OF TYPE-I POLAR STRATOSPHERIC CLOUD FORMATION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ARCTIC STRATOSPHERE; PHYSICAL-CHEMISTRY; LIDAR OBSERVATIONS; OZONE HOLE; AEROSOL; WATER; DENITRIFICATION; SYSTEM; WINTER AB Mechanisms for the formation of Type I (nitric acid-based) polar stratospheric clouds (PSCs) are discussed. If the pre-existing sulfate aerosols are liquid prior to PSC formation, then nitric acid particles (Type Ib) form by HNO3 dissolution in aqueous H2SO4 solution droplets. This process does not require a nucleation step for the formation of HNO3 aerosols, so most pre-existing aerosols grow to become relatively small HNO3-containing particles. At significantly lower temperatures, the resulting supercooled solutions (Type Ib) may freeze to form HNO3 ice particles (Type Ia). If the pre-existing sulfate aerosols are initially solid before PSC formation, then HNO3 vapor can be deposited directly on the frozen sulfate particles. However, because an energy barrier to the condensation exists a nucleation mechanism is involved. Here, we suggest a unique nucleation mechanism that involves formation of HNO3/H2O solutions on the sulfate ice particles. These nucleation processes may be highly selective, resulting in the formation of relatively small number of large particles. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP TABAZADEH, A (reprint author), UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,405 HILGARD AVE,LOS ANGELES,CA 90024, USA. NR 25 TC 163 Z9 164 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 JUL 15 PY 1994 VL 21 IS 15 BP 1619 EP 1622 DI 10.1029/94GL01368 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NX648 UT WOS:A1994NX64800013 ER PT J AU STEVENS, IR POLLOCK, AMT AF STEVENS, IR POLLOCK, AMT TI STAGNATION-POINT FLOW IN COLLIDING-WIND BINARY-SYSTEMS SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE HYDRODYNAMICS; RADIATIVE TRANSFER; BINARIES, GENERAL; STARS, EARLY-TYPE; STARS, MASS-LOSS; X-RAYS, STARS ID RADIATION-DRIVEN WINDS; WOLF-RAYET STARS; O-TYPE STARS; X-RAY; STELLAR WINDS; V444-CYGNI; GENERATION; HD-193793; EMISSION; ORIONIS AB We investigate further the dynamics of colliding winds in hot-star binary systems, by concentrating in this paper on the effects of the radiation pressure of both stars on the material moving between them. Naturally, the presence of a luminous binary companion tends to inhibit the wind acceleration towards the stagnation-point because the resultant radiation force is smaller than in a single star. By also considering the countervailing influence of the companion's gravitational attraction, we derive inequalities governing the stellar mass-loss flux. We find that, in close binary systems, such as V444 Cyg, the winds collide at much lower head-on velocities than those implied by the single-star models used in earlier calculations. This leads directly to lower expected X-ray luminosities and temperatures for colliding hot-star winds, and we suggest that this accounts for the long-standing discrepancies between theory and observation. C1 UNIV BIRMINGHAM,SCH PHYS & SPACE RES,BIRMINGHAM B15 2TT,W MIDLANDS,ENGLAND. COMP & SCI CO LTD,SHEFFIELD S11 7EY,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,HEASARC,CODE 668,GREENBELT,MD 20771. RP STEVENS, IR (reprint author), UNIV CAMBRIDGE,INST ASTRON,MADINGLEY RD,CAMBRIDGE CB3 0HA,ENGLAND. NR 31 TC 70 Z9 70 U1 0 U2 0 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8711 J9 MON NOT R ASTRON SOC JI Mon. Not. Roy. Astron. Soc. PD JUL 15 PY 1994 VL 269 IS 2 BP 226 EP 234 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NY277 UT WOS:A1994NY27700007 ER PT J AU BUHLER, M UMLAUF, E MATHER, JC AF BUHLER, M UMLAUF, E MATHER, JC TI NOISE OF BOLOMETER WITH VANISHING SELF-HEATING SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article ID KINETIC INDUCTANCE THERMOMETER; RAY AB We discuss the thermal noise of a low temperature magnetic bolometer, which has the property of not being heated by the thermometer measurement power. This bolometer is promising for measuring small energy pulses from absorbed single particles or X-rays. Having thermal noise only we can calculate the uncertainty of energy detection and we show that this is not limited by the quantity square-root 4kT2C. This result is of interest with respect to experiments which demand large absorbers. C1 BAYER AKAD WISSENSCH,WALTHER MEISSNER INST TIEFTEMP FORSCH,D-85748 GARCHING,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NR 11 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD JUL 15 PY 1994 VL 346 IS 1-2 BP 225 EP 229 DI 10.1016/0168-9002(94)90708-0 PG 5 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA NW265 UT WOS:A1994NW26500028 ER PT J AU LIDDLE, AR TURNER, MS AF LIDDLE, AR TURNER, MS TI 2ND-ORDER RECONSTRUCTION OF THE INFLATIONARY POTENTIAL SO PHYSICAL REVIEW D LA English DT Article ID COSMOLOGICAL PERTURBATIONS; TENSOR PERTURBATIONS; GRAVITATIONAL-WAVES; EXTENDED INFLATION; UNIVERSE; MODELS; ANISOTROPY; CREATION; SCALE AB To first order in the deviation from scale invariance the inflationary potential and its rst two derivatives can be expressed in terms of the spectral indices of the scalar and tensor perturbations, n and n(T), and their contributions to the variance of the quadrupole CBR temperature anisotropy, S and T. In addition, there is a ''consistency relation'' between these quantities: n(T) = -1/7 (T/S). We discuss the overall strategy of perturbative reconstruction and derive the second-order expressions for the inflationary potential and its first two derivatives and the first-order expression for its third derivative, all in terms of n, n(T), S, T, and dn/d ln k. We also obtain the second-order consistency relation, n(T) = -1/7(T/S)[1 + 0.11(T/S) + 0.15(n - 1)]. As an example we consider the exponential potential, the only known case where exact analytic solutions for the perturbation spectra exist. We reconstruct the potential via Taylor expansion (with coefficients calculated at both first and second order), and introduce the Pade approximant as a greatly improved alternative. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP LIDDLE, AR (reprint author), UNIV SUSSEX,CTR ASTRON,DIV PHYS & ASTRON,BRIGHTON BN1 9QH,E SUSSEX,ENGLAND. NR 27 TC 53 Z9 53 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD JUL 15 PY 1994 VL 50 IS 2 BP 758 EP 768 DI 10.1103/PhysRevD.50.758 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA NY131 UT WOS:A1994NY13100015 ER PT J AU KOLB, EW TKACHEV, II AF KOLB, EW TKACHEV, II TI LARGE-AMPLITUDE ISOTHERMAL FLUCTUATIONS AND HIGH-DENSITY DARK-MATTER CLUMPS SO PHYSICAL REVIEW D LA English DT Article ID AXION MINICLUSTERS; GALACTIC HALO; OBJECTS; MASSES; GALAXY AB Large-amplitude isothermal fluctuations in the dark-matter energy density, parametrized by PHI = deltarho(DM)/rho(DM), are studied within the framework of a spherical collapse model. For PHI greater than or similar to 1, a fluctuation collapses in the radiation-dominated epoch and produces a dense dark-matter object. The final density of the virialized object is found to be rho(F) almost-equal-to 140PHI3(PHI + 1)rho(eq) where rho(eq) is the matter density at equal matter and radiation energy density. This expression is valid for the entire range of possible values of PHI, both for PHI much greater than 1 and PHI much less than 1. Some astrophysical consequences of high-density dark-matter clumps are discussed. C1 UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RUSSIAN ACAD SCI,INST NUCL RES,MOSCOW 117312,RUSSIA. RP KOLB, EW (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510, USA. NR 22 TC 49 Z9 51 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD JUL 15 PY 1994 VL 50 IS 2 BP 769 EP 773 DI 10.1103/PhysRevD.50.769 PG 5 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA NY131 UT WOS:A1994NY13100016 ER PT J AU WEISSMAN, P AF WEISSMAN, P TI COMET SHOEMAKER-LEVY-9 - THE BIG FIZZLE IS COMING SO NATURE LA English DT Editorial Material RP WEISSMAN, P (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 10 TC 13 Z9 13 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 JUL 14 PY 1994 VL 370 IS 6485 BP 94 EP 95 DI 10.1038/370094a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NW804 UT WOS:A1994NW80400025 ER PT J AU LONSDALE, CJ DIAMOND, PJ SMITH, HE LONSDALE, CJ AF LONSDALE, CJ DIAMOND, PJ SMITH, HE LONSDALE, CJ TI COMPACT OH-MEGAMASER AND PROBABLE QUASAR ACTIVITY IN THE GALAXY ARP-220 SO NATURE LA English DT Article ID ULTRALUMINOUS INFRARED GALAXIES; MOLECULAR CLOUDS; IC-4553; STARBURST; EMISSION; NUCLEUS; ARP-220; ORIGIN AB ARP 220 is the prototype far-infrared ultraluminous galaxy, and the origin of its luminosity-a burst of massive star formation or a quasar obscured by a layer of dense gas and dust-has been the subject of much debate(1,2) It also contains the prototypical OH megamaser(3)-an extremely luminous version of masers (microwave lasers) commonly found in our own galaxy. It has been thought that the dense gas in the inner few hundred parsecs of megamaser galaxies acts as a low-gain masing screen, pumped by the far-infrared radiation, which amplifies background continuum emission from the nuclear regions(4-6). Here we show, using new very-long-baseline interferometry observations, that the OH line peak in Arp 220 originates in a structure less than or equal to 1 pc across, positionally aligned with a weak continuum feature, and that most of the emission originates on scales of less than or equal to 10 pc. These results imply that the maser is physically 10-100 times smaller than previously thought(5,6), strongly suggesting that much of the far-infrared radiation from Arp 220 arises in a very small region, possibly a dense molecular torus, surrounding a quasar nucleus. C1 NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. UNIV CALIF SAN DIEGO,DEPT PHYS,LA JOLLA,CA 92093. CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA 91125. RP LONSDALE, CJ (reprint author), MIT,HAYSTACK OBSERV,OFF ROUTE 40,WESTFORD,MA 01886, USA. NR 23 TC 37 Z9 37 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 JUL 14 PY 1994 VL 370 IS 6485 BP 117 EP 120 DI 10.1038/370117a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NW804 UT WOS:A1994NW80400048 ER PT J AU ASPHAUG, E BENZ, W AF ASPHAUG, E BENZ, W TI DENSITY OF COMET SHOEMAKER-LEVY-9 DEDUCED BY MODELING BREAKUP OF THE PARENT RUBBLE-PILE SO NATURE LA English DT Article ID TIDAL DISRUPTION; BODIES AB FOR a week beginning 16 July 1994, fragments of comet Shoemaker-Levy 9 win collide with Jupiter each day. Although the fragments are probably smaller than originally estimated(1), the impacts may nevertheless have observable consequences that will provide valuable insight into the properties of comets and the dynamics of planetary atmospheres. Interpretation of these observations will depend sensitively on parameters such as the mass, density and overall structure of the fragments. To deduce some of these parameters, we have simulated the event that created the fragments-the passage of the parent comet through the tidal field of Jupiter in 1992. Modelling the comet as a strengthless aggregate consisting of a large number of grains, we find that the tidally disrupted body condenses rapidly into clumps, driven by their self-gravity. Formation of a fragment chain resembling Shoemaker-Levy 9 occurs for a narrow range of the simulated comet's bulk density, 0.3-0.7 g cm(-3). A chain of similar to 20 similar-sized fragments matching observations is obtained for a non-rotating parent comet of 1.5 km diameter and bulk density 0.5 g cm(-3), suggesting that the clusters will each liberate similar to 10(27) erg on impact. A slightly larger initial density leads to significant mass variation among the clusters and the possibility of a few similar to 10(28)-erg events. C1 UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RP ASPHAUG, E (reprint author), NASA,AMES RES CTR 2453,MOFFETT FIELD,CA 94035, USA. NR 14 TC 116 Z9 116 U1 0 U2 4 PU MACMILLAN MAGAZINES LTD PI LONDON PA PORTERS SOUTH, 4 CRINAN ST, LONDON, ENGLAND N1 9XW SN 0028-0836 J9 NATURE JI Nature PD JUL 14 PY 1994 VL 370 IS 6485 BP 120 EP 124 DI 10.1038/370120a0 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NW804 UT WOS:A1994NW80400049 ER PT J AU PLATT, J AF PLATT, J TI LIABILITY SOLUTION UNJUST SO MACHINE DESIGN LA English DT Letter RP PLATT, J (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PENTON PUBL INC PI CLEVELAND PA 1100 SUPERIOR AVE, CLEVELAND, OH 44114 SN 0024-9114 J9 MACH DES JI Mach. Des. PD JUL 11 PY 1994 VL 66 IS 13 BP 10 EP & PG 0 WC Engineering, Mechanical SC Engineering GA NX701 UT WOS:A1994NX70100006 ER PT J AU DOWNIE, JD AF DOWNIE, JD TI REAL-TIME HOLOGRAPHIC IMAGE CORRECTION USING BACTERIORHODOPSIN SO APPLIED OPTICS LA English DT Article ID FILMS AB We present experimental results of one-way coherent imaging through a thin phase-aberrating medium using a holographic technique with bacteriorhodopsin as a real-time holographic material. Bacteriorhodopsin is well suited for the application when the aberration is time varying because of its real-time writing and erasing characteristics, sensitivity, and spatial resolution. We show results with final image resolution of greater than 20 line pairs/mm and high signal-to-noise ratio using a polarization-holography approach. RP DOWNIE, JD (reprint author), NASA, AMES RES CTR, MAIL STOP 269-3, MOFFETT FIELD, CA 94035 USA. NR 12 TC 33 Z9 33 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 USA SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD JUL 10 PY 1994 VL 33 IS 20 BP 4353 EP 4357 PG 5 WC Optics SC Optics GA NY095 UT WOS:A1994NY09500003 PM 20935793 ER PT J AU REACH, WT KOO, BC HEILES, C AF REACH, WT KOO, BC HEILES, C TI ATOMIC AND MOLECULAR GAS IN INTERSTELLAR CIRRUS CLOUDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; ISM, CLOUDS; ISM, MOLECULES; RADIO LINES, ISM ID ZETA OPHIUCHI; H-I; INFRARED CIRRUS; CARBON-MONOXIDE; CO; HYDROGEN; ABUNDANCES; C-12/C-13; CHEMISTRY; EMISSION AB The dust, atomic gas, and molecular gas content of a sample of 26 of isolated, degree-sized infrared clouds are compared. Half of the clouds have an infrared excess indicating the presence of H-2, and 14 contain compact CO-emitting regions. Complete, high angular resolution H I and CO maps of one cloud, G236 + 39, resolve the transition between atomic and molecular H, as well as the location of CO formation. Assuming the infrared emission traces the total column density, H-2 is inferred to be much more widely distributed than the CO. The CO rotational levels are subthermally excited, and the (2-1)/(1-0) line ratios suggest a density n(H-2) approximately 200 cm-3 where CO was detected. A model of H-2 formation on grain surfaces balanced by self-shielded photodissociation fits the variation of infrared brightness with H I column density. AssuMing a temperature of 80 K, typical of diffuse H-2 (Savage et al. 1977), the H-2 chemistry requires an average density n(H + 2H2) approximately 50 cm-3. For G236 + 39, if the distance is 100 pc, the H I and H-2 masses are estimated to be 90 and 70 M., respectively. High-resolution H I and infrared maps of a smaller cloud, G249.0 + 73.7, reveal no evidence for molecular gas, which is likely due to the low total column density through this cloud. These results suggest the H-2 and H I content are comparable for some interstellar cirrus clouds with column densities N(H I) > 4 x 10(20) cm-2, even where CO was not detected. C1 UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. SEOUL NATL UNIV,DEPT ASTRON,SEOUL 151742,SOUTH KOREA. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP REACH, WT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 685,GREENBELT,MD 20771, USA. RI Reach, William/C-4710-2008; OI Reach, William/0000-0001-8362-4094 NR 45 TC 98 Z9 98 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1994 VL 429 IS 2 BP 672 EP 693 DI 10.1086/174353 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW014 UT WOS:A1994NW01400020 ER PT J AU FREUDENREICH, HT BERRIMAN, GB DWEK, E HAUSER, MG KELSALL, T MOSELEY, SH SILVERBERG, RF SODROSKI, TJ TOLLER, GN WEILAND, JL AF FREUDENREICH, HT BERRIMAN, GB DWEK, E HAUSER, MG KELSALL, T MOSELEY, SH SILVERBERG, RF SODROSKI, TJ TOLLER, GN WEILAND, JL TI DIRBE EVIDENCE FOR A WARP IN THE INTERSTELLAR DUST LAYER AND STELLAR DISK OF THE GALAXY SO ASTROPHYSICAL JOURNAL LA English DT Letter DE GALAXIES, PHOTOMETRY; GALAXY, STRUCTURE; ISM, STRUCTURE ID ON SPIRAL GALAXIES; SURFACE PHOTOMETRY; GALACTIC WARP; MORPHOLOGY; MODEL AB The Diffuse Infrared Background Experiment (DIRBE) of the Cosmic Background Explorer (COBE) has mapped the surface brightness distributions of the Galactic plane at wavelengths from 1.25 to 240 mum. In these maps the latitude of peak brightness, as a function of longitude, traces a roughly sinusoidal curve of period approximately 360-degrees. In the far-infrared, where emission by interstellar dust dominates the surface brightness, this curve agrees well with that derived from maps of the velocity-integrated H I, suggesting that the layers of dust and neutral atomic hydrogen are similarly displaced from the Galactic plane. In the near-infrared (lambda < 5 mum), where old disk stars dominate the emission, the brightness crest exhibits the same phase but roughly half the amplitude. The reduced amplitude of the warp in stellar light could result from a lesser warping of the stellar disk, or from a more rapid falloff of the density of stars relative to the density of gas, possibly due to a radial truncation of the disk. C1 NASA,GODDARD SPACE FLIGHT CTR,GEN SCI CORP,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,APPL RES CORP,GREENBELT,MD 20771. RP FREUDENREICH, HT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,CODE 6859,GREENBELT,MD 20771, USA. RI Moseley, Harvey/D-5069-2012; Dwek, Eli/C-3995-2012 NR 26 TC 42 Z9 44 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 10 PY 1994 VL 429 IS 2 BP L69 EP L72 DI 10.1086/187415 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW015 UT WOS:A1994NW01500006 ER PT J AU QUATTROCHI, DA RIDD, MK AF QUATTROCHI, DA RIDD, MK TI MEASUREMENT AND ANALYSIS OF THERMAL-ENERGY RESPONSES FROM DISCRETE URBAN SURFACES USING REMOTE-SENSING DATA SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID HEAT ISLANDS; BALANCE; SATELLITE; RADIATION; EVAPOTRANSPIRATION; CLIMATOLOGY AB This study employs data from the airborne thermal Infrared Multispectral Scanner (TIMS) to measure thermal (i.e., longwave) energy responses, emitted or upwelling, from discrete surfaces that are typical of the city landscape within Salt Lake City, Utah, over a single diurnal time period (i.e., a single day/night-time sequence). These data are used to quantify the disposition of thermal energy for selected urban surfaces during the daytime and night-time, and the amount of change in thermal response or flux recorded between day and night. An analysis is presented on the thermal interrelationships observed for common urban materials for day, night, and flux, as identified from the TIMS data through the delineation of discrete surface type polygons. The results from the study illustrate that such factors as heat capacity, thermal conductivity, and the amount of soil moisture available have a profound impact on the magnitude of thermal energy emanating from a specific surface and on the dynamics of longwave energy response between day and night. C1 UNIV UTAH, DEPT GEOG, SALT LAKE CITY, UT 84112 USA. RP NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, DIV EARTH SCI & APPLICAT, HUNTSVILLE, AL 35812 USA. NR 43 TC 50 Z9 52 U1 1 U2 6 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 2-4 PARK SQUARE, MILTON PARK, ABINGDON OR14 4RN, OXON, ENGLAND SN 0143-1161 EI 1366-5901 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD JUL 10 PY 1994 VL 15 IS 10 BP 1991 EP 2022 PG 32 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA PD649 UT WOS:A1994PD64900004 ER PT J AU PLESNIAK, MW MEHTA, RD JOHNSTON, JP AF PLESNIAK, MW MEHTA, RD JOHNSTON, JP TI CURVED 2-STREAM TURBULENT MIXING LAYERS - 3-DIMENSIONAL STRUCTURE AND STREAMWISE EVOLUTION SO JOURNAL OF FLUID MECHANICS LA English DT Article ID FREE SHEAR LAYERS; BOUNDARY-LAYERS; VORTICAL STRUCTURES; INITIAL CONDITIONS; SURFACE CURVATURE; CONCAVE SURFACE; PLANE; FLOW; WALL AB The three-dimensional structure and streamwise evolution of two-stream mixing layers at high Reynolds numbers (Re(delta) almost-equal-to 2.7 x 10(4)) were studied experimentally to determine the effects of mild streamwise curvature (delta/RBAR < 3%). Mixing layers with velocity ratios of 0.6 and both laminar and turbulent initial boundary layers, were subjected to stabilizing and destabilizing longitudinal curvature (in the Taylor-Gortler sense). The mixing layer is affected by the angular momentum instability when the low-speed stream is on the outside of the curve, and it is stabilized when the streams are reversed so that the high-speed stream is on the outside. In both stable and unstable mixing layers, originating from laminar boundary layers, well-organized spatially stationary streamwise vorticity was generated, which produced significant spanwise variations in the mean velocity and Reynolds stress distributions. These vortical structures appear to result from the amplification of small incoming disturbances (as in the straight mixing layer), rather than through the Taylor-Gortler instability. Although the mean streamwise vorticity decayed with downstream distance in both cases, the rate of decay for the unstable case was lower. With the initial boundary layers on the splitter plate turbulent, spatially stationary streamwise vorticity was not generated in either the stable or unstable mixing layer. Linear growth was achieved for both initial conditions, but the rate of growth for the unstable case was higher than that of the stable case. Correspondingly, the far-field spanwise-averaged peak Reynolds stresses were significantly higher for the destabilized cases than for the stabilized cases, which exhibited levels comparable to, or slightly lower than, those for the straight case. A part of the Reynolds stress increase in the unstable layer is attributed to 'extra' production through terms in the transport equations which are activated by the angular momentum instability. Velocity spectra also indicated significant differences in the turbulence structure of the two cases, both in the near- and far-field regions. C1 STANFORD UNIV, JIAA, DEPT AERONAUT & ASTRONAUT, STANFORD, CA 94305 USA. NASA, AMES RES CTR, FLUID MECH LAB, MOFFETT FIELD, CA 94035 USA. STANFORD UNIV, DEPT MECH ENGN, STANFORD, CA 94305 USA. RP PLESNIAK, MW (reprint author), PURDUE UNIV, SCH MECH ENGN, W LAFAYETTE, IN 47907 USA. OI Plesniak, Michael/0000-0001-6575-5074 NR 51 TC 20 Z9 21 U1 0 U2 3 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 32 AVENUE OF THE AMERICAS, NEW YORK, NY 10013-2473 USA SN 0022-1120 EI 1469-7645 J9 J FLUID MECH JI J. Fluid Mech. PD JUL 10 PY 1994 VL 270 BP 1 EP 50 DI 10.1017/S0022112094004180 PG 50 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA NY667 UT WOS:A1994NY66700001 ER PT J AU CRIMINALE, WO JACKSON, TL LASSEIGNE, DG AF CRIMINALE, WO JACKSON, TL LASSEIGNE, DG TI EVOLUTION OF DISTURBANCES IN STAGNATION-POINT FLOW SO JOURNAL OF FLUID MECHANICS LA English DT Article ID SWEPT ATTACHMENT LINE; STABILITY AB The evolution of three-dimensional disturbances in an incompressible three-dimensional stagnation-point flow in an inviscid fluid is investigated. Since it is not possible to apply classical normal-mode analysis to the disturbance equations for the fully three-dimensional stagnation-point flow to obtain solutions, an initial-value problem is solved instead. The evolution of the disturbances provides the necessary information to determine stability and indeed the complete transient as well. It is found that when considering the disturbance energy, the planar stagnation-point flow, which is independent of one of the transverse coordinates, represents a neutrally stable flow whereas the fully three-dimensional flow is either stable or unstable, depending on whether the flow is away from or towards the stagnation point in the transverse direction that is neglected in the planar stagnation point. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. OLD DOMINION UNIV,DEPT MATH & STAT,NORFOLK,VA 23529. RP CRIMINALE, WO (reprint author), UNIV WASHINGTON,DEPT APPL MATH,SEATTLE,WA 98195, USA. NR 14 TC 15 Z9 15 U1 0 U2 0 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0022-1120 J9 J FLUID MECH JI J. Fluid Mech. PD JUL 10 PY 1994 VL 270 BP 331 EP 347 DI 10.1017/S0022112094004295 PG 17 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA NY667 UT WOS:A1994NY66700012 ER PT J AU NGO, T SNYDER, EJ TONG, WM WILLIAMS, RS ANDERSON, MS AF NGO, T SNYDER, EJ TONG, WM WILLIAMS, RS ANDERSON, MS TI O-ATOM ETCHING OF GRAPHITE IN LOW-EARTH-ORBIT SO SURFACE SCIENCE LA English DT Letter ID GROWTH; CONTINUUM; MODELS; BEAMS AB Samples of highly ordered pyrolytic graphite were placed aboard the space shuttle Atlantis (mission STS46) and exposed to the atmosphere present in low earth orbit to observe the effects of chemical etching by atomic oxygen on carbon-based materials. During the 43 h exposure, approximately 2.25 mum of graphite were removed from the sample, which corresponds to an etch yield of one C atom for every eight incident O atoms. The topography of the etched samples was analyzed quantitatively within the framework of scaling theory, and the experimental data agree with the static scaling behavior predicted for a model in which surface diffusion and reaction at step edges dominates the etching mechanism. C1 UNIV CALIF LOS ANGELES, DEPT CHEM & BIOCHEM, LOS ANGELES, CA 90024 USA. UNIV CALIF LOS ANGELES, DEPT PHYS, LOS ANGELES, CA 90024 USA. JET PROP LAB, PASADENA, CA 91109 USA. RI Tong, William/D-2564-2010; Williams, R. Stanley/A-8281-2009 OI Williams, R. Stanley/0000-0003-0213-4259 NR 23 TC 30 Z9 31 U1 0 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0039-6028 J9 SURF SCI JI Surf. Sci. PD JUL 10 PY 1994 VL 314 IS 1 BP L817 EP L822 DI 10.1016/0039-6028(94)90201-1 PG 6 WC Chemistry, Physical; Physics, Condensed Matter SC Chemistry; Physics GA NX332 UT WOS:A1994NX33200001 ER PT J AU KOUVELIOTOU, C AF KOUVELIOTOU, C TI GAMMA-RAY BURSTS STILL A MYSTERY SO NATURE LA English DT Letter ID HIGH-ENERGY TRANSIENT RP KOUVELIOTOU, C (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35812, USA. NR 11 TC 9 Z9 9 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 JUL 7 PY 1994 VL 370 IS 6484 BP 26 EP 26 DI 10.1038/370026a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NV711 UT WOS:A1994NV71100039 ER PT J AU CHATTERJEE, B RINGEL, SA SIEG, R HOFFMAN, R WEINBERG, I AF CHATTERJEE, B RINGEL, SA SIEG, R HOFFMAN, R WEINBERG, I TI HYDROGEN PASSIVATION OF DISLOCATIONS IN INP ON GAAS HETEROSTRUCTURES SO APPLIED PHYSICS LETTERS LA English DT Article AB The effects of hydrogenation on the properties of Zn-doped InP/GaAs heterostructures grown by metalorganic chemical vapor deposition were studied by current-voltage (I-V), deep level transient spectroscopy (DLTS), and photoluminescence. Significant improvements in leakage current and breakdown voltage in InP diodes on GaAs were observed after a 2 h hydrogen plasma exposure at 250-degrees-C. DLTS indicated a corresponding reduction in total trap concentration from approximately 6 x 10(14) to approximately 3 x 10(12) cm-3 at a depth of approximately 1.5 mum below the surface. The Zn dopants were completely reactivated by a subsequent 5 min 400-degrees-C anneal without degradation of the reverse current or reactivation of the deep levels. Anneals in excess of 580-degrees-C were necessary to reactivate the deep levels and degrade the leakage current to their original values, indicating the passivation of threading dislocations by hydrogen, and the existence of a wide temperature window for post-passivation processing. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHATTERJEE, B (reprint author), OAK RIDGE NATL LAB,DEPT ELECT ENGN,ELECTR MAT & DEVICES LAB,OAK RIDGE,TN 37830, USA. RI Schaff, William/B-5839-2009 NR 11 TC 34 Z9 34 U1 0 U2 8 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 JUL 4 PY 1994 VL 65 IS 1 BP 58 EP 60 DI 10.1063/1.113073 PG 3 WC Physics, Applied SC Physics GA NW223 UT WOS:A1994NW22300020 ER PT J AU MURTHY, G WATENPAUGH, DE BALLARD, RE HARGENS, AR AF MURTHY, G WATENPAUGH, DE BALLARD, RE HARGENS, AR TI EXERCISE AGAINST LOWER-BODY NEGATIVE-PRESSURE AS A COUNTERMEASURE FOR CARDIOVASCULAR AND MUSCULOSKELETAL DECONDITIONING SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 10th IAA Man in Space Symposium: At the Threshold of the 21st-Century CY APR 19-23, 1993 CL TOKYO, JAPAN SP INT ACAD ASTRONAUT, UNION SPACE SCI JAPAN, NATL AEROSP LAB, INST SPACE & ASTRONAUT SCI, NATL SPACE DEV AGCY JAPAN, PRIME MINISTERS OFF, SCI & TECH AGCY, MINIST EDUC SCI & CULTURE, MINIST HLTH & WELFARE, NIHON UNIV AB Exposure to lower body negative pressure (LBNP) with oral salt and water ingestion has been tested by astronauts as a countermeasure to prevent postflight orthostatic intolerance. Exercise is another countermeasure that astronauts commonly use during spaceflight to maintain musculoskeletal strength. We hypothesize that a novel combination of exercise and simultaneous exposure to lower body negative pressure during spaceflight will produce Earth-like musculoskeletal loads as well as cardiovascular stimuli to maintain adaptation to Earth's gravity. Results from recent studies indicate that leg exercise within a LBNP chamber against the suction force of 100 mmHg LBNP in horizontal-supine posture produces an equivalent, if not greater exercise stress compared to similar leg exercise in upright posture (without LBNP) against Earth's gravity.12 Therefore, the concept of LBNP combined with exercise may prove to be a low cost and low mass technique to stress the cardiovascular and the musculoskeletal systems simultaneously. RP MURTHY, G (reprint author), NASA,AMES RES CTR,DIV LIFE SCI 239-11,MOFFETT FIELD,CA 94035, USA. NR 0 TC 11 Z9 11 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD JUL PY 1994 VL 33 BP 89 EP 96 DI 10.1016/0094-5765(94)90112-0 PG 8 WC Engineering, Aerospace SC Engineering GA PJ372 UT WOS:A1994PJ37200013 PM 11539542 ER PT J AU VERNIKOS, J CONVERTINO, VA AF VERNIKOS, J CONVERTINO, VA TI ADVANTAGES AND DISADVANTAGES OF FLUDROCORTISONE OR SALINE LOAD IN PREVENTING POST-SPACEFLIGHT ORTHOSTATIC HYPOTENSION SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 10th IAA Man in Space Symposium: At the Threshold of the 21st-Century CY APR 19-23, 1993 CL TOKYO, JAPAN SP INT ACAD ASTRONAUT, UNION SPACE SCI JAPAN, NATL AEROSP LAB, INST SPACE & ASTRONAUT SCI, NATL SPACE DEV AGCY JAPAN, PRIME MINISTERS OFF, SCI & TECH AGCY, MINIST EDUC SCI & CULTURE, MINIST HLTH & WELFARE, NIHON UNIV AB The purpose of this study was to compare the effectiveness of saline load to fludrocortisone (florinef) as countermeasures for reduced plasma volume and orthostatic intolerance after spaceflight. Eleven males (ages 30-50 yr) underwent a 3-day ambulatory baseline period followed by 7 days of 6-degrees head-down bedrest, during which cardiopulmonary and arterial baroreflex sensitivity and plasma volume (PV) were determined. During pre-bedrest and 2.5 h after treatment on day 8, PV was also measured and subjects underwent a 15-min unsupported stand test. Treatments consisted of 8 salt tablets (1 g NaCl per tablet) and 960 ml of water in 5 subjects and 0.6 mg (0.2 mg x 3) over 24 h in the other 6 subjects. PV decreased by 12% on day 7 of bedrest. This was restored on day 8 by florinef but not by saline load. The effect of florinef on PV was paralleled by decreases in urine volume and the urinary sodium/potassium ratio. Reduced PV was associated with greater vascular resistance for the same drop in central venous pressure, suggesting less vasoconstriction reserve after bedrest. Carotid baroreflex control of heart rate was attenuated after 7 days of bedrest. Both baroreflex functions were restored by florinef but not saline load. Only 1 of 6 subjects showed syncopal symptoms in the florinef-treated group, whereas 4 of 5 subjects did so in the saline-load group. Acute florinef treatment appears to have distinct advantages as a protective measure for post-bedrest orthostatic intolerance, not only through its salt retaining, volume-expanding mineralcorticoid effect, but possibly through its actions on baroreflex and sympathetic functions. RP VERNIKOS, J (reprint author), NASA HEADQUARTERS,WASHINGTON,DC 20546, USA. NR 0 TC 21 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 JUL PY 1994 VL 33 BP 259 EP 266 DI 10.1016/0094-5765(94)90133-3 PG 8 WC Engineering, Aerospace SC Engineering GA PJ372 UT WOS:A1994PJ37200034 PM 11537971 ER PT J AU SIBILLE, L PUSEY, ML AF SIBILLE, L PUSEY, ML TI INVESTIGATION OF NUCLEATING LYSOZYME SOLUTIONS SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Article; Proceedings Paper CT 5th International Conference on the Crystallization of Biological Macromolecules (ICCBM)/National-Institute-of-Health Membrane Crystallization Workshop CY AUG 08-13, 1993 CL SAN DIEGO, CA SP NIH ID PROTEIN AB This laboratory has explored the potential of a combination of three analytical techniques to study the nucleation of chicken egg-white lysozyme. Collisional quenching of the fluorescent molecule SPQ [6-methoxy-N-(3-sulfopropyl)quinolinium] by chloride ions was used to determine the binding of the crystallizing agent to the protein at equilibrium and kinetically. Calorimetric measurements show that this binding generates an exothermic peak larger than the energy released during the early stages of nucleation. Light scattering intensity measurements were used to follow the aggregation kinetics. RP SIBILLE, L (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 10 TC 16 Z9 16 U1 0 U2 0 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0907-4449 J9 ACTA CRYSTALLOGR D JI Acta Crystallogr. Sect. D-Biol. Crystallogr. PD JUL 1 PY 1994 VL 50 BP 396 EP 397 DI 10.1107/S0907444993013447 PN 4 PG 2 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA NY475 UT WOS:A1994NY47500011 PM 15299391 ER PT J AU EWING, F FORSYTHE, E PUSEY, M AF EWING, F FORSYTHE, E PUSEY, M TI ORTHORHOMBIC LYSOZYME SOLUBILITY SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Article; Proceedings Paper CT 5th International Conference on the Crystallization of Biological Macromolecules (ICCBM)/National-Institute-of-Health Membrane Crystallization Workshop CY AUG 08-13, 1993 CL SAN DIEGO, CA SP NIH ID EGG-WHITE LYSOZYME; CRYSTAL-GROWTH; PROTEIN SOLUBILITIES; PHASE-TRANSITION; TEMPERATURE; CRYSTALLIZATION; EXAMPLE; FORM AB The orthorhombic, or high-temperature, form of chicken egg-white lysozyme typically appears at temPeratures greater-than-or-equal-to 298 K. Solubility diagrams have been determined for this form of lysozyme from pH 4.0 to 5.4 in 0.2 pH increments using the micro-column technique. Data were collected in the 297-317 K temperature range which resulted in phase diagrams similar in overall shape to those obtained for the lower temperature tetragonal form. Specifically, the solubility increased with increasing temperature and decreased with increasing precipitant concentration. However, the solubility of the orthorhombic form is considerably less sensitive to temperature than the tetragonal form, resulting in a more flattened slope. On the other hand, pH effects on the high-temperature form were opposite to those on the low-temperature form. When holding the precipitant concentration constant, the solubility decreased with increasing pH for the orthorhombic form. Previous tetragonal data were incorporated with these orthorhombic data to produce intercept values. These values varied with both pH and precipitant concentration, but the general tendency of the slope was to decrease with increasing pH. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. SCI & TECHNOL CORP,MADISON,AL 35758. UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35806. NR 25 TC 48 Z9 48 U1 1 U2 2 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0907-4449 J9 ACTA CRYSTALLOGR D JI Acta Crystallogr. Sect. D-Biol. Crystallogr. PD JUL 1 PY 1994 VL 50 BP 424 EP 428 DI 10.1107/S0907444993014428 PN 4 PG 5 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA NY475 UT WOS:A1994NY47500016 PM 15299396 ER PT J AU FORSYTHE, E EWING, F PUSEY, M AF FORSYTHE, E EWING, F PUSEY, M TI STUDIES ON TETRAGONAL LYSOZYME CRYSTAL-GROWTH RATES SO ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY LA English DT Article; Proceedings Paper CT 5th International Conference on the Crystallization of Biological Macromolecules (ICCBM)/National-Institute-of-Health Membrane Crystallization Workshop CY AUG 08-13, 1993 CL SAN DIEGO, CA SP NIH ID PROTEIN CRYSTALLIZATION; KINETICS AB A computer-controlled apparatus able to simultaneously follow the face growth rate of up to 40 crystals was developed. This apparatus was used to investigate the effects of solution pH on the (110) and (101) face growth rates of tetragonal lysozyme. Growth rates were measured at pH 4.0, 4.4, 4.8 and 5.2, in 0.1 M sodium acetate buffer with 5 % NaCl, 295 K. Initial crystal sizes ranged from 10 to 40 mum. Plots of log supersaturation ratio (either C/C(sat) or C/C(sat) - 1) versus log(growth rate) are not linear, typically having a slope of approximately 8 at the lowest growth rates determined (10(-6) mum s-1), which falls off to a slope of approximately 2 at the highest growth rates (10(-2) mum s-1) measured. Ratios of C/C(sat) ranged from 4 to > 20. The data show that lower solubility solutions require higher supersaturation ratios for equivalent growth rates. Data for the growth rate of the (101) face at pH 4.0 were widely scattered, especially at lower supersaturation ratios. Time-lapse video of crystals at low supersaturations shows that initially only the (110) faces grow, leaving 'notches' at the (110)-(110) corners. These corners then fill in and macro-steps appear on the (101) faces which rapidly move inward in the form of an octagon, restoring the crystal to a 'normal' appearance. This phenomenon has been observed for tetragonal crystals grown in either still or flowing solutions. Flowing solutions at lower supersaturations also gave cases where the corners did not fill in, with the (110) faces continuing to grow out until growth ceased. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35806. SCI & TECHNOL CORP,MADISON,AL 35758. NR 16 TC 37 Z9 37 U1 0 U2 1 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0907-4449 J9 ACTA CRYSTALLOGR D JI Acta Crystallogr. Sect. D-Biol. Crystallogr. PD JUL 1 PY 1994 VL 50 BP 614 EP 619 DI 10.1107/S0907444993013344 PN 4 PG 6 WC Biochemical Research Methods; Biochemistry & Molecular Biology; Biophysics; Crystallography SC Biochemistry & Molecular Biology; Biophysics; Crystallography GA NY475 UT WOS:A1994NY47500045 PM 15299425 ER PT J AU FORCE, C AF FORCE, C TI WHY THE MOON SO AEROSPACE AMERICA LA English DT Editorial Material RP FORCE, C (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1994 VL 32 IS 7 BP 3 EP 3 PG 1 WC Engineering, Aerospace SC Engineering GA NU608 UT WOS:A1994NU60800001 ER PT J AU BEKEY, I AF BEKEY, I TI SSTO ROCKETS - A PRACTICAL POSSIBILITY SO AEROSPACE AMERICA LA English DT Article RP BEKEY, I (reprint author), NASA,OFF SPACE SCI DEV,WASHINGTON,DC 20546, USA. NR 0 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD JUL PY 1994 VL 32 IS 7 BP 32 EP 37 PG 6 WC Engineering, Aerospace SC Engineering GA NU608 UT WOS:A1994NU60800009 ER PT J AU MEADOWS, KR CAUGHEY, DA CASPER, J AF MEADOWS, KR CAUGHEY, DA CASPER, J TI COMPUTING UNSTEADY SHOCK-WAVES FOR AEROACOUSTIC APPLICATIONS SO AIAA JOURNAL LA English DT Article ID DIFFERENCE-SCHEMES AB The computation of unsteady shock waves, which contribute significantly to noise generation in supersonic jet flows, is investigated. The paper focuses on the difficulties of computing slowly moving shock waves. Numerical error is found to manifest itself principally as a spurious entropy wave. Calculations presented are performed using a third-order essentially nonoscillatory scheme. The effect of stencil biasing parameters and of two versions of numerical flux formulas on the magnitude of spurious entropy are investigated. The level of numerical error introduced in the calculation is quantified as a function of shock pressure ratio, shock speed, Courant number, and mesh density. The spurious entropy relative to the entropy jump across a static shock decreases with increasing shock strength and shock velocity relative to the grid, but is insensitive to Courant number. The structure of the spurious entropy wave is affected by the choice of flux formulas and algorithm biasing parameters. The effect of the spurious numerical waves on the calculation of sound amplification by a shock wave is investigated. For this class of problem, the acoustic pressure waves are relatively unaffected by the spurious numerical phenomena. C1 CORNELL UNIV,SIBLEY SCH MECH & AEROSP ENGN,ITHACA,NY 14853. ADV TECHNOL RES GRP,HAMPTON,VA 23666. RP MEADOWS, KR (reprint author), NASA,LANGLEY RES CTR,AEROACOUST BRANCH,HAMPTON,VA 23681, USA. NR 19 TC 3 Z9 3 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1994 VL 32 IS 7 BP 1360 EP 1366 DI 10.2514/3.12203 PG 7 WC Engineering, Aerospace SC Engineering GA NW275 UT WOS:A1994NW27500003 ER PT J AU MAESTRELLO, L AF MAESTRELLO, L TI CONTROL-NONLINEAR-NONSTATIONARY STRUCTURAL RESPONSE AND RADIATION NEAR A SUPERSONIC JET SO AIAA JOURNAL LA English DT Article ID NOISE; TRANSITION; BOUNDARY; PLATE AB This paper is on the control of nonlinear-nonstationary vibration of a frame-stringer structure resulting from high levels of excitation from a nearby supersonic jet exhaust. The structure exhibits periodic, chaotic, or random behaviors when forced by high-intensity sound from a supersonic jet exhaust with ''shock'' loading superimposed on a broadband response. The time history of the pressure, showing the rotation and flapping of the shock structure in the jet column due to large-scale instabilities, indicates that the response is not only nonlinear but also nonstationary. The acoustic pressure radiated by the structure also contains shocks and the formation of harmonics with distance. Control of the structural response is achieved by actively forcing the structure with an actuator at the shock oscillation frequency whose amplitude is locked into a self-control cycle. Results show that the peak power level is reduced by a factor of 63, or 18 dB. As a result, new broadband components emerge with at least four harmonics. At accelerating and decelerating supersonic speeds, the exhaust from the jet induces higher transient loading on the nearby flexible structure due to the occurrence of multiple shocks from the jet. RP MAESTRELLO, L (reprint author), NASA,LANGLEY RES CTR,DIV ACOUST & FLUID MECH,STRUCT ACOUST BRANCH,HAMPTON,VA 23681, USA. NR 45 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1994 VL 32 IS 7 BP 1367 EP 1376 DI 10.2514/3.12204 PG 10 WC Engineering, Aerospace SC Engineering GA NW275 UT WOS:A1994NW27500004 ER PT J AU MOSS, JN MITCHELTREE, RA DOGRA, VK WILMOTH, RG AF MOSS, JN MITCHELTREE, RA DOGRA, VK WILMOTH, RG TI DIRECT SIMULATION MONTE-CARLO AND NAVIER-STOKES SIMULATIONS OF BLUNT-BODY WAKE FLOWS SO AIAA JOURNAL LA English DT Article AB Numerical results obtained with direct simulation Monte Carlo and Navier-Stokes methods are presented for a Mach-20 nitrogen flow about a 70-deg blunted cone. The flow conditions simulated are those that can be obtained is existing low-density hypersonic wind tunnels. Three sets of flow conditions are considered with freestream Knudsen numbers ranging from 0.03 to 0.001. The focus is on the wake structure: how the wake structure changes as a function of rarefaction, what the afterbody levels of heating are, and to what limits the continuum models are as rarefaction in the wake is progressively increased. Calculations are made with and without an afterbody sting. Results for the afterbody sting are emphasized in anticipation of an experimental study for the current flow conditions and model configuration. The Navier-Stokes calculations were made with and without slip boundary conditions. Comparisons of the results obtained with the two simulation methodologies are made for both flowfield structure and surface quantities. C1 VIGYAN INC,HAMPTON,VA 23666. RP MOSS, JN (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 22 TC 12 Z9 13 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 JUL PY 1994 VL 32 IS 7 BP 1399 EP 1406 DI 10.2514/3.12208 PG 8 WC Engineering, Aerospace SC Engineering GA NW275 UT WOS:A1994NW27500008 ER PT J AU NOOR, AK STARNES, JH PETERS, JM AF NOOR, AK STARNES, JH PETERS, JM TI THERMOMECHANICAL BUCKLING OF MULTILAYERED COMPOSITE PANELS WITH CUTOUTS SO AIAA JOURNAL LA English DT Article ID PLATES; HOLE AB A study is made of the thermomechanical buckling of flat unstiffened composite panels with central circular cutouts. The panels are subjected to combined temperature changes and applied edge loading (or edge displacements). The analysis is based on a first-order shear deformation plate theory. A mixed formulation is used with the fundamental unknowns consisting of the generalized displacements and the stress resultants of the plate. Both the stability boundary and the sensitivity coefficients are evaluated. The sensitivity coefficients measure the sensitivity of the buckling response to variations in the different lamination and material parameters of the panel. Numerical results are presented showing the effects of the variations in the hole diameter, laminate stacking sequence, fiber orientation, and aspect ratio of the panel on the thermomechanical buckling response and its sensitivity coefficients. RP NOOR, AK (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 19 TC 9 Z9 10 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUL PY 1994 VL 32 IS 7 BP 1507 EP 1519 DI 10.2514/3.12222 PG 13 WC Engineering, Aerospace SC Engineering GA NW275 UT WOS:A1994NW27500022 ER PT J AU LAKE, RC NIXON, MW WILBUR, ML SINGLETON, JD MIRICK, PH AF LAKE, RC NIXON, MW WILBUR, ML SINGLETON, JD MIRICK, PH TI DEMONSTRATION OF AN ELASTICALLY COUPLED TWIST CONTROL CONCEPT FOR TILT ROTOR BLADE APPLICATION SO AIAA JOURNAL LA English DT Note RP LAKE, RC (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 5 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 JUL PY 1994 VL 32 IS 7 BP 1549 EP 1551 DI 10.2514/3.12232 PG 3 WC Engineering, Aerospace SC Engineering GA NW275 UT WOS:A1994NW27500034 ER PT J AU GRANT, WB AF GRANT, WB TI OPTICAL REMOTE-SENSING FOR MEASUREMENT OF TOXIC GASES SO AMERICAN CERAMIC SOCIETY BULLETIN LA English DT Article AB There is renewed interest in using optical remote sensing techniques for measuring and monitoring airborne toxics. Many instruments have been used to measure traces of atmospheric molecular species. RP GRANT, WB (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. RI Grant, William/B-8311-2009 OI Grant, William/0000-0002-1439-3285 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7812 J9 AM CERAM SOC BULL JI Am. Ceram. Soc. Bull. PD JUL PY 1994 VL 73 IS 7 BP 79 EP 82 PG 4 WC Materials Science, Ceramics SC Materials Science GA NV843 UT WOS:A1994NV84300006 ER PT J AU GOLDBERGER, AL BUNGO, MW BAEVSKY, RM BENNETT, BS RIGNEY, DR MIETUS, JE NIKULINA, GA CHARLES, JB AF GOLDBERGER, AL BUNGO, MW BAEVSKY, RM BENNETT, BS RIGNEY, DR MIETUS, JE NIKULINA, GA CHARLES, JB TI HEART-RATE DYNAMICS DURING LONG-TERM SPACE-FLIGHT - REPORT ON MIR COSMONAUTS SO AMERICAN HEART JOURNAL LA English DT Note ID SHORT-DURATION SPACEFLIGHT C1 HARVARD UNIV,SCH MED,BOSTON,MA. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. MOSCOW BIOMED PROBLEMS INST,MOSCOW,RUSSIA. KRUG LIFE SCI,HOUSTON,TX. RP GOLDBERGER, AL (reprint author), BETH ISRAEL HOSP,DIV CARDIOVASC,330 BROOKLINE AVE,GZ-435,BOSTON,MA 02215, USA. NR 6 TC 28 Z9 29 U1 0 U2 3 PU MOSBY-YEAR BOOK INC PI ST LOUIS PA 11830 WESTLINE INDUSTRIAL DR, ST LOUIS, MO 63146-3318 SN 0002-8703 J9 AM HEART J JI Am. Heart J. PD JUL PY 1994 VL 128 IS 1 BP 202 EP 204 DI 10.1016/0002-8703(94)90033-7 PG 3 WC Cardiac & Cardiovascular Systems SC Cardiovascular System & Cardiology GA NV840 UT WOS:A1994NV84000032 PM 8017279 ER PT J AU LYBANON, M AF LYBANON, M TI SATELLITE ALTIMETRY OF THE GULF-STREAM SO AMERICAN JOURNAL OF PHYSICS LA English DT Article RP LYBANON, M (reprint author), USN,RES LAB,STENNIS SPACE CTR,REMOTE SENSING APPLICAT BRANCH,WASHINGTON,DC 20375, USA. NR 10 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 0002-9505 J9 AM J PHYS JI Am. J. Phys. PD JUL PY 1994 VL 62 IS 7 BP 661 EP 665 DI 10.1119/1.17489 PG 5 WC Education, Scientific Disciplines; Physics, Multidisciplinary SC Education & Educational Research; Physics GA NT931 UT WOS:A1994NT93100020 ER PT J AU GRINDELAND, RE ROY, RR EDGERTON, VR GROSSMAN, EJ MUKKU, VR JIANG, B PIEROTTI, DJ RUDOLPH, I AF GRINDELAND, RE ROY, RR EDGERTON, VR GROSSMAN, EJ MUKKU, VR JIANG, B PIEROTTI, DJ RUDOLPH, I TI INTERACTIVE EFFECTS OF GROWTH-HORMONE AND EXERCISE ON MUSCLE MASS IN SUSPENDED RATS SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE COUNTERMEASURES; HINDLIMB SUSPENSION; MUSCLE ATROPHY; GROWTH HORMONE; EXERCISE; SIMULATED MICROGRAVITY ID PERIODIC WEIGHT SUPPORT; SKELETAL-MUSCLE; HINDLIMB SUSPENSION; MEDIAL GASTROCNEMIUS; ANABOLIC-STEROIDS; SOLEUS FIBERS; SPACEFLIGHT; ATROPHY AB Measures to attenuate muscle atrophy in rats in response to simulated microgravity [hindlimb suspension (HS)] have been only partially successful. In the present study, hypophysectomized rats were in HS for 7 days, and the effects of recombinant human growth hormone (G H), exercise (Ex), or GH+Ex on the weights, protein concentrations, and fiber cross-sectional areas (CSAs) of hindlimb muscles were determined. The weights of four extensor muscles, i.e., the soleus (Sol), medial (MG) and lateral (LG) gastrocnemius, and plantaris (Plt), and one adductor, i.e., the adductor longus (AL), were decreased by 10-22% after HS. Fiber CSAs were decreased by 34% in the Sol and by 17% in the MG after HS. In contrast, two flexors, i.e., the tibialis anterior (TA) and extensor digitorum longus (EDL), did not atrophy. In HS rats, GH treatment alone maintained the weights of the fast extensors (MG, LG, Plt) and flexors (TA, EDL) at or above those of control rats. This effect was not observed in the slow extensor (Sol) or AL. Exercise had no significant effect on the weight of any muscle in HS rats. A combination of GH and Ex treatments yielded a significant increase in the weights of the fast extensors and in the CSA of both fast and slow fibers of the MG and significantly increased Sol weight and CSA of the slow fibers of the Sol. The AL was not responsive to either GH or Ex treatments. Protein concentrations of the Sol and MG were higher only in the Sol of Ex and GH+Ex rats. These results suggest that while GH treatment or intermittent high-intensity exercise alone have a minimal effect in maintaining the mass of unloaded muscle, there is a strong interactive effect of these two treatments. C1 UNIV CALIF LOS ANGELES,BRAIN RES INST,LOS ANGELES,CA 90024. UNIV CALIF LOS ANGELES,DEPT PHYSIOL SCI,LOS ANGELES,CA 90024. GENENTECH INC,S SAN FRANCISCO,CA 94080. RP GRINDELAND, RE (reprint author), NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035, USA. NR 35 TC 50 Z9 50 U1 0 U2 3 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD JUL PY 1994 VL 267 IS 1 BP R316 EP R322 PN 2 PG 7 WC Physiology SC Physiology GA NY985 UT WOS:A1994NY98500093 PM 8048638 ER PT J AU BANFIELD, JF WASILEWSKI, PJ VEBLEN, DR AF BANFIELD, JF WASILEWSKI, PJ VEBLEN, DR TI TEM STUDY OF RELATIONSHIPS BETWEEN THE MICROSTRUCTURES AND MAGNETIC-PROPERTIES OF STRONGLY MAGNETIZED MAGNETITE AND MAGHEMITE SO AMERICAN MINERALOGIST LA English DT Article ID LOW-TEMPERATURE OXIDATION; TITANOMAGNETITE AB This study investigates relationships between microstructures revealed Dy transmission electron microscopy (TEM) and the magnetic properties of strongly magnetized magnetite iron ore previously described as type I lodestone. The sample consists mostly of magnetite with some maghemite (approximately 30%) and minor hematite and goethite oxidation products (< 5%). The maghemite exhibits a weakly developed superstructure that in some areas is consistent with the enantiomorphous space groups P4(1)32 and P4(3)32. High-resolution imaging indicates that magnetite and maghemite contain closely spaced planar faults parallel to {101}. Displacement vector analyses and high-resolution imaging indicate [1/4 1/4 0] translations across most faults. Faults cannot arise merely by oxidation and vacancy ordering because they offset the magnetite substructure. Boundaries that show no offset of the magnetite substructure probably represent junctions between enantiomorphous maghemite domains. Although superlattices are not sufficiently well developed to allow detailed characterization of the vacancy ordering patterns, we can establish that the [1/4 1/4 0] boundaries generally separate regions of the same phase and not regions of magnetite from maghemite. Needle-shaped areas defined by planar faults are elongate along the magnetically soft [111] direction, and defect orientations correspond to the usual orientations of magnetic domain walls in magnetite. As noted previously, Fe-O-Fe bond angles across {101} faults allow direct reversal of the magnetic moments. Modification of magnetic vector orientations would require either nucleation of new domain walls or the movement of faults. Three specific thermal regimes (20-280, 280-425, and 425-600-degrees-C) are derived from a series of thermomagnetic experiments; each regime is associated with the movement of the natural remanent magnetization (NRM) vector. The ratio of NRM to saturation remanent magnetization is large, consistent with lightning-discharge induced magnetization. In the first regime, 80% of the NRM is destroyed, the coercivity is substantially reduced, and the magnetic susceptibility increases. These changes correlate with the elimination of most stacking faults from the sample. We suggest that the initial high coercivity is directly associated with the presence of stacking faults and that pinning of domain walls by these features primarily explains the large and stable natural remanence. The shape anisotropy of the magnetite and maghemite regions may also be important. We tentatively suggest that the stacking faults may also have been induced in the lightning event. The second thermal regime, characterized by rapid reduction in susceptibility and saturation magnetization, corresponds to the conversion of maghemite to hematite. The third regime is dominated by magnetite and hematite. Results demonstrate that microstructural detail revealed by TEM contributes substantially to the understanding of mineral magnetic properties. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. JOHNS HOPKINS UNIV,DEPT EARTH & PLANETARY SCI,BALTIMORE,MD 21218. RP BANFIELD, JF (reprint author), UNIV WISCONSIN,DEPT GEOL & GEOPHYS,MADISON,WI 53706, USA. NR 26 TC 22 Z9 22 U1 0 U2 14 PU MINERALOGICAL SOC AMER PI WASHINGTON PA 1130 17TH ST NW SUITE 330, WASHINGTON, DC 20036 SN 0003-004X J9 AM MINERAL JI Am. Miner. PD JUL-AUG PY 1994 VL 79 IS 7-8 BP 654 EP 667 PG 14 WC Geochemistry & Geophysics; Mineralogy SC Geochemistry & Geophysics; Mineralogy GA PC429 UT WOS:A1994PC42900007 ER PT J AU REDDY, CA RAVINDRAN, S VISWANATHAN, KS MURTHY, BVK RAO, DRK ARAKI, T AF REDDY, CA RAVINDRAN, S VISWANATHAN, KS MURTHY, BVK RAO, DRK ARAKI, T TI OBSERVATIONS OF PC5 MICROPULSATION-RELATED ELECTRIC-FIELD OSCILLATIONS IN THE EQUATORIAL IONOSPHERE SO ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES LA English DT Article ID VHF RADAR OBSERVATIONS; AZIMUTHAL WAVE-NUMBER; LINE RESONANCES; SURFACE-WAVES; ULF WAVES; MAGNETOSPHERE; PULSATIONS; CURRENTS; IMPULSE; PERIOD AB A 54.95-MHz coherent backscatter radar, an ionosonde and the magnetometer located at Trivandrum in India (8.5-degrees-N, 77-degrees-E, 0.5-degrees-N dip angle) recorded large-amplitude ionospheric fluctuations and magnetic field fluctuations associated with a Pc5 micropulsation event, which occurred during an intense magnetic storm on 24 March 1991 (A(p) = 161). Simultaneous 100-nT-level fluctuations are also observed in the H-component at Brorfelde, Denmark (55.6-degrees-N gm) and at Narsarsuaq, Greenland (70.6-degrees-N gm). Our study of the above observations shows that the E-W electric field fluctuations in the E- and F-regions and the magnetic field fluctuations at Thumba are dominated by a near-sinusoidal oscillation of 10 min during 1730-1900 IST (1200-1330 UT), the amplitude of the electric field oscillation in the equatorial electrojet (EEJ) is 0.1-0.25 mV m-1 and it increases with height, while it is about 1.0 mV m-1 in the F-region, the ground-level H-component oscillation can be accounted for by the ionospheric current oscillation generated by the observed electric field oscillation in the EEJ and the H-component oscillations at Trivandrum and Brorfelde are in phase with each other. The observations are interpreted in terms of a compressional cavity mode resonance in the inner magnetosphere and the associated ionospheric electric field penetrating from high latitudes to the magnetic equator. C1 VIKRAM SARABHAI SPACE CTR,SPACE PHYS LAB,TRIVANDRUM 695022,KERALA,INDIA. NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES BRANCH,GREENBELT,MD 20771. INDIAN INST GEOMAGNETISM,BOMBAY 400005,INDIA. KYOTO UNIV,INST GEOPHYS,KYOTO 606,JAPAN. NR 42 TC 19 Z9 19 U1 0 U2 6 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0992-7689 J9 ANN GEOPHYS JI Ann. Geophys.-Atmos. Hydrospheres Space Sci. PD JUL PY 1994 VL 12 IS 6 BP 565 EP 573 DI 10.1007/s00585-994-0565-7 PG 9 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA PA390 UT WOS:A1994PA39000012 ER PT J AU MA, K LAMB, M CHEN, P WILSON, T COOLEY, R XIA, H FOWLER, C CHEN, Q CHU, WK AF MA, K LAMB, M CHEN, P WILSON, T COOLEY, R XIA, H FOWLER, C CHEN, Q CHU, WK TI A NATURAL APPLICATION FOR HIGH-TEMPERATURE SUPERCONDUCTORS - A BEARING FOR THE AZIMUTH MOUNT OF A LUNAR TELESCOPE SO APPLIED SUPERCONDUCTIVITY LA English DT Article AB A bearing for telescope mounts on the moon has to Function in a cold dusty vacuum environment that impairs the operation of almost all traditional bearings, but it is a natural environment For bearings constructed out of magnets and high temperature superconductors. The challenge lies not so much in the weight of the telescope that has to be supported, but in the smoothness of forces required for precision positioning control over a long stretch of time without human intervention. In this paper, we present a design of hybrid superconductor magnet bearings intended for use on the azimuth mount of an altitude-azimuth telescope mount system. In addition to the general features of hybrid super conducting magnet bearings, we will address particular issues connected with the application of these bearings on a telescope mount. C1 UNIV HOUSTON,DEPT PHYS,HOUSTON,TX 77204. COMP SCI CORP,CALVERTON,MD 20705. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP MA, K (reprint author), UNIV HOUSTON,TEXAS CTR SUPERCONDUCT,HOUSTON,TX 77204, USA. NR 11 TC 3 Z9 3 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0964-1807 J9 APPL SUPERCOND JI Appl. Supercond. PD JUL-AUG PY 1994 VL 2 IS 7-8 BP 479 EP 486 DI 10.1016/0964-1807(94)90038-8 PG 8 WC Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Materials Science; Physics GA QX167 UT WOS:A1994QX16700006 ER PT J AU DEWEY, RJ AF DEWEY, RJ TI THE EFFECTS OF CORRELATED NOISE IN PHASED-ARRAY OBSERVATIONS OF RADIO-SOURCES SO ASTRONOMICAL JOURNAL LA English DT Article AB Arrays of radio telescopes are now routinely used to provide increased signal-to-noise when observing faint point sources. However, calculation of the achievable sensitivity is complicated if there are sources in the field of view other than the target source. These additional sources not only increase the system temperatures of the individual antennas, but may also contribute significant ''correlated noise'' to the effective system temperature of the array. This problem has been of particular interest in the context of tracking spacecraft in the vicinity of radio-bright planets (e.g., Galileo at Jupiter), but it has broader astronomical relevance as well. This paper presents a general formulation of the problem, for the case of a point-like target source in the presence of an additional radio source of arbitrary brightness distribution. We re-derive the well known result that, in the absence of any background sources, a phased array of N identical antennas is a factor of N more sensitive than a single antenna. We also show that an unphased array of N identical antennas is, on average, no more sensitive than a single antenna if the signals from the individual antennas are combined prior to detection. In the case where a background source is present we show that the effects of correlated noise are highly geometry dependent, and for some astronomical observations may cause significant fluctuations in the array's effective system temperature. RP DEWEY, RJ (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 16 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 0004-6256 J9 ASTRON J JI Astron. J. PD JUL PY 1994 VL 108 IS 1 BP 337 EP 345 DI 10.1086/117073 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT501 UT WOS:A1994NT50100034 ER PT J AU FOLKNER, WM CHARLOT, P FINGER, MH WILLIAMS, JG SOVERS, OJ NEWHALL, XX STANDISH, EM AF FOLKNER, WM CHARLOT, P FINGER, MH WILLIAMS, JG SOVERS, OJ NEWHALL, XX STANDISH, EM TI DETERMINATION O THE EXTRAGALACTIC-PLANETARY FRAME TIE FROM JOINT ANALYSIS OF RADIO INTERFEROMETRIC AND LUNAR LASER RANGING MEASUREMENTS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE REFERENCE SYSTEMS; ASTROMETRY; EPHEMERIDES ID FORCED NUTATIONS; DEFINITION; SYSTEM; EARTH; ORIENTATION; EPHEMERIDES; PRECESSION; ASTROMETRY; MOTION AB Very Long Baseline Interferometry (VLBI) observations of extragalactic radio sources provide the basis for defining an accurate non-rotating reference frame in terms of the angular positions of the sources. Measurements of the distance from the Earth to the Moon and to the inner planets provide the basis for defining an inertial planetary ephemeris reference frame. The relative orientation, or frame tie, between these two reference frames is of interest for combining Earth orientation measurements, for comparing Earth orientation results with theories referred to the mean equator and equinox, and for determining the positions of the planets with respect to the extragalactic reference frame. This work presents an indirect determination of the extragalactic-planetary frame tie from a combined reduction of VLBI and Lunar Laser Ranging (LLR) observations. For this determination, data acquired by LLR tracking stations since 1969 have been analyzed and combined with 14 years of VLBI data acquired by NASA's Deep Space Network since 1978. The frame tie derived from this joint analysis, with an accuracy of 0.003'', is the most accurate determination obtained so far. This result, combined with a determination of the mean ecliptic (defined in the rotating sense), shows that the mean equinox of epoch J2000 is offset from the x-axis of the extragalactic frame adopted by the International Earth Rotation Service for astrometric and geodetic applications by 0.078'' +/- 0.010'' along the y-direction and by (0.019'' +/- 0.002'' along the z-direction. C1 OBSERV PARIS, CENT BUR IERS, CNRS, URA 1125, F-75014 PARIS, FRANCE. COMP SCI CORP, ASTRON PROGRAMS, MARSHALL SPACE FLIGHT CTR, AL 35812 USA. RP FOLKNER, WM (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 48 TC 42 Z9 45 U1 3 U2 3 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 1994 VL 287 IS 1 BP 279 EP 289 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NV514 UT WOS:A1994NV51400035 ER PT J AU ALTENHOFF, WJ JOHNSTON, KJ STUMPFF, P WEBSTER, WJ AF ALTENHOFF, WJ JOHNSTON, KJ STUMPFF, P WEBSTER, WJ TI MILLIMETER-WAVELENGTH OBSERVATIONS OF MINOR PLANETS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE RADIATION MECHANISMS, THERMAL; MINOR PLANETS, ASTEROIDS; PLANETS AND SATELLITES, INDIVIDUAL, MARS; RADIO CONTINUUM, SOLAR SYSTEM ID OCCULTATION; VESTA; SUBMILLIMETER; PALLAS; CERES AB Bolometer observations at 250 GHz of fifteen minor planets have shown that the emissivity of these objects is close to unity. This results in an independent method to determine the absolute calibration scale of radio observations at mm wavelengths: Applying our results to Mars, the prime calibrator at this wavelength, gives a mean absolute disk temperature at mean solar distance of almost-equal-to 210 K. Further, the diameters of circularly symmetric asteroids can be determined or the surface area of asteroids can be estimated assuming some geometric constraints on their shape. C1 USN OBSERV, WASHINGTON, DC 20392 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP ALTENHOFF, WJ (reprint author), MAX PLANCK INST RADIOASTRON, AUF HUGEL 69, D-53121 BONN, GERMANY. NR 26 TC 18 Z9 18 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 1994 VL 287 IS 2 BP 641 EP 646 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW311 UT WOS:A1994NW31100040 ER PT J AU JENNISKENS, P AF JENNISKENS, P TI METEOR STREAM ACTIVITY .1. THE ANNUAL STREAMS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE METEORS, METEOROIDS; COMETS, GENERAL ID RADAR OBSERVATIONS; EVOLUTION; SHOWER; MASS; RADIANT; FLUX AB Between 1981 and 1991, a small group of amateur meteor observers in Australia and the Netherlands counted meteors during 4,482 hours of effective observing time. These counts have been reduced and are to be presented here as a first homogeneous set of some 50 meteor stream activity curves for all major and many minor meteor streams on both hemispheres. Together with the sporadic background, these give an accurate picture of annual meteor activity. Empirical corrections are given that relate the observed meteor rates to well defined Zenith Hourly Rates (ZHR). It is found that all major streams are well represented by a set of exponential curves: ZHR = ZHR(max)10-B\lambda.-lambda.(max)\. Values of ZHR(max) and B are given. There is no evidence for stable sub-maxima in the activity profiles. In four, and possibly six, cases, there is evidence for a background component in the activity curve. In all cases, the background is more extended to small solar longitude lambda.. From a fit of the above dependence to the rates of minor streams, it is found that the slopes of most high inclination (i> 15-degrees) streams have a characteristic value of B = 0.19 +/- 0.08 per degree of solar longitude increase in the 10log of the ZHR. The ZHR is transformed into mass influx rates, from which the total mass in the meteoroid stream is estimated by making an assumption about the distribution of matter perpendicular to the path of the Earth. Total masses of the observed streams are of order 10(14) to 10(16) g. C1 NASA, AMES RES CTR, MAIL STOP 239-4, MOFFETT FIELD, CA 94035 USA. DUTCH METEOR SOC, 2318 NB LEIDEN, NETHERLANDS. NR 115 TC 160 Z9 163 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUL PY 1994 VL 287 IS 3 BP 990 EP 1013 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NX977 UT WOS:A1994NX97700030 ER PT J AU FRY, JN SCHERRER, RJ AF FRY, JN SCHERRER, RJ TI SKEWNESS IN LARGE-SCALE STRUCTURE AND NON-GAUSSIAN INITIAL CONDITIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, CLUSTERING; LARGE-SCALE STRUCTURE OF THE UNIVERSE ID DENSITY PERTURBATIONS; FLUCTUATIONS; MODELS; STATISTICS AB We compute the skewness of the galaxy distribution arising from the nonlinear evolution of arbitrary non-Gaussian initial conditions to second order in perturbation theory including the effects of nonlinear biasing. The result contains a term identical to that for a Gaussian initial distribution plus terms which depend on the skewness and kurtosis of the initial conditions. The results are model dependent; we present calculations for several toy models. At late times, the leading contribution from initial skewness decays away relative to the other terms and becomes increasingly unimportant, but the contribution from initial kurtosis, previously overlooked, has the same time dependence as the Gaussian terms. Observations of a linear dependence of the normalized skewness on the rms density fluctuation therefore do not necessarily rule out initially non-Gaussian models. We also show that with non-Gaussian initial conditions the first correction to linear theory for the mean square density fluctuation is larger than for Gaussian models. C1 UNIV FLORIDA,DEPT PHYS,GAINESVILLE,FL 32611. OHIO STATE UNIV,DEPT PHYS,COLUMBUS,OH 43210. RP FRY, JN (reprint author), NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,GAINESVILLE,FL 32611, USA. NR 21 TC 59 Z9 59 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1994 VL 429 IS 1 BP 36 EP 42 DI 10.1086/174300 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800005 ER PT J AU CONTOPOULOS, J LOVELACE, RVE AF CONTOPOULOS, J LOVELACE, RVE TI MAGNETICALLY DRIVEN JETS AND WINDS - EXACT-SOLUTIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, JETS; ISM, JETS AND OUTFLOWS; MHD; STARS, MASS LOSS ID MAGNETIZED ACCRETION DISKS; SHOCKED RELATIVISTIC JETS; SYNCHROTRON EMISSION; HYDROMAGNETIC FLOWS; ASTROPHYSICAL JETS; BL-LACERTAE; MODEL AB We present a general class of self-similar solutions of the full set of MHD equations that include matter flow, electromagnetic fields, pressure, and gravity. The solutions represent axisymmetric, time-independent, nonrelativistic, ideal, magnetohydrodynamic, collimated outflows (jets and winds) from magnetized accretion disks around compact objects. The magnetic field extracts angular momentum from the disk, accelerates the outflows perpendicular to the disk, and provides collimation at large distances. The terminal outflow velocities are of the order of or greater than the rotational velocity of the disk at the base of the flow. When a nonzero electric current flows along the jet, the outflow radius oscillates with axial distance, whereas when the total electric current is zero (with the return current flowing across the jet's cross section), the outflow radius increases to a maximum and then decreases. The method can also be applied to relativistic outflows. C1 CORNELL UNIV,APPL PHYS LAB,ITHACA,NY 14853. RP CONTOPOULOS, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 31 TC 155 Z9 155 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1994 VL 429 IS 1 BP 139 EP 152 DI 10.1086/174307 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800012 ER PT J AU HILL, RJ MADORE, BF FREEDMAN, WL AF HILL, RJ MADORE, BF FREEDMAN, WL TI THE INITIAL MASS FUNCTION FOR MASSIVE STARS IN THE MAGELLANIC CLOUDS .2. INTERSTELLAR REDDENING TOWARD 14-OB ASSOCIATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; MAGELLANIC CLOUDS; OPEN CLUSTERS AND ASSOCIATIONS, GENERAL; STARS, EARLY-TYPE ID EXTINCTION LAW; ULTRAVIOLET; DUST AB We have used UBV CCD photometry to determine the interstellar reddening toward 14 OB associations in the Magellanic Clouds. The two reddening-free indices available in the UBV system were used to obtain the reddening estimates. The mean color excesses of the associations range from E(B - V) = 0.01-0,26 mag in the LMC and from E(B - V) = 0.06-0.25 mag in the SMC. We have modeled the observed scatter in the color excesses of individual stars within the associations and find that statistically significant differential reddening exists in at least some of the associations. C1 CALTECH,JET PROP LAB,NASA,IPAC,CTR EXTRAGALACT DATABASE INFRARED PROC,PASADENA,CA 91125. UNIV TORONTO,DEPT ASTRON,TORONTO M5S 1A1,ONTARIO,CANADA. RP HILL, RJ (reprint author), CARNEGIE INST WASHINGTON OBSERV,813 SANTA BARBARA ST,PASADENA,CA 91101, USA. NR 24 TC 20 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 JUL 1 PY 1994 VL 429 IS 1 BP 192 EP 203 DI 10.1086/174311 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800016 ER PT J AU HILL, RJ MADORE, BF FREEDMAN, WL AF HILL, RJ MADORE, BF FREEDMAN, WL TI THE INITIAL MASS FUNCTION FOR MASSIVE STARS IN THE MAGELLANIC CLOUDS .3. LUMINOSITY AND MASS FUNCTIONS FOR 14 OB ASSOCIATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE MAGELLANIC CLOUDS; OPEN CLUSTERS AND ASSOCIATIONS, GENERAL; STARS, LUMINOSITY FUNCTION, MASS FUNCTION ID MAIN-SEQUENCE LUMINOSITY; WOLF-RAYET STARS; STELLAR CONTENT; EVOLUTIONARY MODELS; SOLAR NEIGHBORHOOD; FAINT STARS; HR DIAGRAM; CLUSTERS; GALAXIES; LMC AB We have used UBV photometry of stars in 14 associations in the Large and Small Magellanic Clouds (Hill, Madore, & Freedman) to derive luminosity and mass functions for the most massive stars. The main-sequence luminosity functions for the associations are quite similar, having an average slope of s = 0.30 +/- 0.06. The mass functions for the associations have slopes that span similar ranges about a common mean for both the LMC and SMC and there is no strong evidence for a significant variation in the slopes from one association to another. Accordingly, metal abundance does not appear to have a strong effect on the IMF, at least for the range in metallicity observed between the Magellanic Clouds. The average slope of the IMF for the Magellanic Cloud associations is GAMMA = - 2.0 +/- 0.5 for M > 9 M.. The range in the derived slopes is more likely due to the large uncertainties associated with the calculations of the mass functions, rather than to real variations in the IMF. There may be some evidence for a decrease in the slope of the IMF at masses below 9 M., but incompleteness and the larger photometric errors associated with the faintest stars make this conclusion tentative. C1 CALTECH,JET PROP LAB,NASA,IPAC,CTR EXTRAGALACT DATABASE INFRARED PROC,PASADENA,CA 91125. UNIV TORONTO,DEPT ASTRON,TORONTO M5S 1A1,ONTARIO,CANADA. RP HILL, RJ (reprint author), CARNEGIE INST WASHINGTON OBSERV,813 SANTA BARBARA ST,PASADENA,CA 91101, USA. NR 78 TC 34 Z9 34 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1994 VL 429 IS 1 BP 204 EP 224 DI 10.1086/174312 PN 1 PG 21 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800017 ER PT J AU HORACK, JM KOSHUT, TM MALLOZZI, RS STOREY, SD EMSLIE, AG AF HORACK, JM KOSHUT, TM MALLOZZI, RS STOREY, SD EMSLIE, AG TI IMPLICATIONS OF THE BATSE DATA FOR A HELIOCENTRIC ORIGIN OF GAMMA-RAY BURSTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS ID COMET CLOUD; OORT CLOUD AB Several possible models have been suggested to explain the observed distribution of gamma-ray bursts: heliocentric distributions such as the Oort cloud, large galactic halos, and cosmological models. We report here on an investigation into the implications of the Burst and Transient Source Experiment (BATSE) gamma-ray burst distribution (Meegan et al. 1992a) data on the possible heliocentric origin of gamma-ray bursts. We find no statistically significant anisotropy in the angular distribution of the bursts in a Sun-referenced coordinate system; there is no dipole moment in the direction of the Sun, and no quadrupole moment associated with the ecliptic plane. We have employed direct analytic calculations and Monte Carlo simulations of sources in the Oort cloud to constrain possible heliocentric burst distributions. These can produce distributions consistent with the observed angular isotropy, [V/V(max)], and the observed C/C(min) distribution of BATSE, and provide limits to burst energy of a few times approximately 10(27) ergs. However, the agreement of the heliocentric C/C(min) distributions with the BATSE data is attributable to the relatively limited sampling of strong, nearby bursts. These bursts are known from observation to be homogeneously distributed, yet the density of sources in the Oort cloud is not constant in this region. Integral number-intensity distributions from the Oort cloud for larger numbers of bursts cannot reproduce the known homogeneity of the strong bursts without modification to the computed cometary number density and are therefore unlikely explanations of the gamma-ray burst distribution. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. RP HORACK, JM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES-66,HUNTSVILLE,AL 35812, USA. RI Horack, John/J-6670-2016 NR 27 TC 14 Z9 14 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1994 VL 429 IS 1 BP 319 EP 324 DI 10.1086/174320 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800025 ER PT J AU DAUGHERTY, JK HARDING, AK AF DAUGHERTY, JK HARDING, AK TI POLAR-CAP MODELS OF GAMMA-RAY PULSARS - EMISSION FROM SINGLE POLES OF NEARLY ALIGNED ROTATORS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, THEORY; PULSARS, GENERAL; RADIATION MECHANISMS, NONTHERMAL ID RAPIDLY SPINNING PULSARS; ENERGETIC RADIATION; MAGNETIC-FIELDS; PAIR PRODUCTION; GEMINGA; GAPS; VELA AB We compare a new Monte Carlo simulation of polar cap models for gamma-ray pulsars with observations of sources detected above 10 MeV by the Compton Observatory. We find that for models in which the inclination of the magnetic axis is comparable to the angular radius of the polar cap, the radiation from a single cap may exhibit a pulse with either a single broad peak as in PSR 1706-44 and PSR 1055-52, or a doubly peaked profile comparable to those observed from the Crab, Vela, and Geminga pulsars. In general, double pulses are seen by observers whose line of sight penetrates into the cap interior and are due to enhanced emission near the rim. For cascades induced by curvature radiation, increased rim emission occurs even when electrons are accelerated over the entire cap, since electrons from the interior escape along magnetic field lines with less curvature and hence emit less radiation. However, we obtain better fits to the duty cycles of observed profiles if we make the empirical assumption that acceleration occurs only near the rim. In either case, the model energy spectra are consistent with most of the observed sources. The beaming factors expected from nearly aligned rotators, based on standard estimates for the cap radius, imply that their luminosities need not be as large as in the case of orthogonal rotators. However, small beam angles are also a difficulty with this model because they imply low detection probabilities. In either case the polar cap radius is a critical factor, and in this context we point out that plasma loading of the field lines should make the caps larger than the usual estimates based on pure dipole fields. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP DAUGHERTY, JK (reprint author), UNIV N CAROLINA,DEPT COMP SCI,ASHEVILLE,NC 28804, USA. RI Harding, Alice/D-3160-2012 NR 33 TC 69 Z9 69 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1994 VL 429 IS 1 BP 325 EP 330 DI 10.1086/174321 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800026 ER PT J AU TITARCHUK, L AF TITARCHUK, L TI ON THE SPECTRA OF X-RAY BURSTERS - EXPANSION AND CONTRACTION STAGES SO ASTROPHYSICAL JOURNAL LA English DT Article DE RADIATIVE TRANSFER; STARS, NEUTRON; X-RAYS, BURSTS ID BURSTING NEUTRON STARS; MODEL ATMOSPHERES; RADIUS EXPANSION AB The theory of spectral formation during the explosion and contraction stages of X-ray bursters, which include the effects of Comptonization and free-free absorption and emission, is described. Analytical expressions are provided for color ratios, and the spectral shape is given as a function of input parameters, elemental abundance, neutron star mass and radius, and Eddington ratio. An Eulerian calculation is used to determine the photospheric evolution accurately during the Eddington luminosity phase. The developed analytical theory for hydrodynamics of the expansion takes into account the dependence of Compton scattering opacity on electron temperature. An analytic expression is derived from the sonic point position and the value of the sonic velocity. Using this value as a boundary condition at the sonic point, the velocity, density, and temperature profile are calculated throughout the whole photosphere. It is shown that the atmosphere radiates spectra having a low-energy power-law shape and blackbody-like hard tail. In the expansion stage the spectra depend strongly on the temperature of the helium-burning zone at the neutron star surface. The X-ray photospheric radius increases to approximately 100 km or more, depending on the condition of the nuclear burning on the surface of the neutron star in the course of the expansion. RP TITARCHUK, L (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY PHYS LAB,GREENBELT,MD 20771, USA. NR 26 TC 45 Z9 45 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1994 VL 429 IS 1 BP 340 EP 355 DI 10.1086/174323 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800028 ER PT J AU WHITE, SM DUNCAN, RA LIM, J NELSON, GJ DRAKE, SA KUNDU, MR AF WHITE, SM DUNCAN, RA LIM, J NELSON, GJ DRAKE, SA KUNDU, MR TI THE RADIO-SOURCE AROUND ETA-CARINAE SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; RADIO CONTINUUM, STARS; STARS, INDIVIDUAL (ETA CARINAE); SUPERGIANTS ID NEBULA; ULTRAVIOLET; MODEL; STARS; SHELL AB We present high spatial resolution radio observations of the peculiar southern star eta Carinae, made with the Australia Telescope. The images, at 8 and 9 GHz with a resolution of 1.0'', show a source of dimension 10'' and total flux of 0.7 Jy dominated by a strong central peak. The radio emission is unpolarized and offers no support to models which invoke degenerate stars or more exotic objects within the core of eta Car. In these data we find no evidence for more than one energy source in the core with arcsecond separations as some infrared observations have suggested. Several levels of structure are evident in the radio image, which shows symmetry on the larger scales. Conventional formulae for stellar wind radio sources give a mass loss rate of order 3 x 10(-4) M. yr-1 based on the radio flux in the central peak, which yields a wind momentum flux of order 20% of the momentum flux available from the star's radiation field. The radio emission at these frequencies is consistent with thermal emission from gas flowing away from a ''luminous blue variable'' star (LBV). Eta car is probably the brightest thermal stellar wind radio source in the sky. C1 AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. ATNF,PAUL WILD OBSERV,NARRABRI,NSW 2390,AUSTRALIA. CALTECH,PASADENA,CA 91125. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP WHITE, SM (reprint author), UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742, USA. NR 29 TC 31 Z9 31 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1994 VL 429 IS 1 BP 380 EP 384 DI 10.1086/174327 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800032 ER PT J AU STOTHERS, RB AF STOTHERS, RB TI CROSS-CORRELATION OF POINT SERIES USING A NEW METHOD SO ASTROPHYSICAL JOURNAL LA English DT Article DE METHODS, NUMERICAL; METHODS, STATISTICAL; SOLAR-TERRESTRIAL RELATIONS AB Traditional methods of cross-correlation of two time series do not apply to point time series. Here, a new method, devised specifically for point series, utilizes a correlation measure that is based on the rms difference (or, alternatively, the median absolute difference) between nearest neighbors in overlapped segments of the two series. Error estimates for the observed locations of the points, as well as a systematic shift of one series with respect to the other to accommodate a constant, but unknown, lead or lag, are easily incorporated into the analysis using Monte Carlo techniques. A methodological restriction adopted here is that one series be treated as a template series against which the other, called the target series, is cross-correlated. To estimate a significance level for the correlation measure, the adopted alternative (null) hypothesis is that the target series arises from a homogeneous Poisson process. The new method is applied to cross-correlating the times of the greatest geomagnetic storms with the times of maximum in the undecennial solar activity cycle. RP STOTHERS, RB (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,GREENBELT,MD 20771, USA. NR 13 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1994 VL 429 IS 1 BP 415 EP 418 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800037 ER PT J AU JOHANSSON, S NAVE, G GELLER, M SAUVAL, AJ GREVESSE, N SCHOENFELD, WG CHANG, ES FARMER, CB AF JOHANSSON, S NAVE, G GELLER, M SAUVAL, AJ GREVESSE, N SCHOENFELD, WG CHANG, ES FARMER, CB TI ANALYSIS OF THE 3D(6)4S(6D)4F-5G SUPERMULTIPLET OF FE-I IN LABORATORY AND SOLAR INFRARED-SPECTRA SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC DATA; LINE, IDENTIFICATION; SUN, INFRARED ID FOURIER-TRANSFORM; ABUNDANCE; LINES; IRON; STRENGTHS AB The combined laboratory and solar analysis of the highly excited subconfigurations 3d(6)4s(6D)4f and 3d(6)4s(6D)5g of Fe I has allowed us to classify 87 lines of the 4f-5g supermultiplet in the spectral region 2545-2585 cm-1. The level structure of these JK-coupled configurations is predicted by semiempirical calculations and the quadrupolic approximation. Semiempirical gf-values have been calculated and are compared to gf-values derived from the solar spectrum. The solar analysis has shown that these lines, which should be much less sensitive than lower excitation lines to departures from LTE and to temperature uncertainties, lead to a solar abundance of iron which is consistent with the meteoritic value (A(Fe) = 7.51). C1 UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. UNIV MASSACHUSETTS,DEPT PHYS & ASTRON,AMHERST,MA 01003. LUND OBSERV,LUND,SWEDEN. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. JET PROP LAB,PASADENA,CA 91109. OBSERV ROYAL BELG,B-1180 BRUSSELS,BELGIUM. RP JOHANSSON, S (reprint author), LUND UNIV,DEPT PHYS,S-22362 LUND,SWEDEN. NR 27 TC 13 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUL 1 PY 1994 VL 429 IS 1 BP 419 EP 426 DI 10.1086/174333 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT958 UT WOS:A1994NT95800038 ER PT J AU VANPARADIJS, J TELESCO, CM KOUVELIOTOU, C FISHMAN, GJ AF VANPARADIJS, J TELESCO, CM KOUVELIOTOU, C FISHMAN, GJ TI 10 MICRON DETECTION OF THE HARD X-RAY TRANSIENT GRO J0422+32 - FREE-FREE EMISSION FROM AN X-RAY DRIVEN ACCRETION DISK WIND SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; BINARIES, CLOSE; STARS, INDIVIDUAL (GRO-J0422+32) ID MULTIWAVELENGTH CAMPAIGN; OPTICAL COUNTERPART; INTERSTELLAR GRAINS; SCORPIUS X-1; NOVA; IUE AB We report the detection of 10 mum emission from the transient low-mass X-ray binary (LMXB) and optical nova GRO J0422+32 near the maximum of its outburst. We discuss this result in terms of (1) a ''standard'' model according to which low-energy radiation of LMXB is caused by reprocessing of X-rays in an accretion disk; (2) emission from a cool secondary star; (3) emission from dust grains heated by the transient X-rays, and (4) free-free emission from an X-ray-driven wind from the accretion disk. Only the fourth alternative provides a viable explanation for the observed 10 mum emission, with a mass-loss rate in the disk wind that may be substantially higher than the rate of accretion onto the compact star. The presence of such a wind may have a profound effect on the evolution of the binary, and contribute to the solution of the ''birthrate problem'' of millisecond radio pulsars. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. CTR HIGH ENERGY ASTROPHYS,AMSTERDAM,NETHERLANDS. RP VANPARADIJS, J (reprint author), UNIV AMSTERDAM,ASTRON INST ANTON PANNEKOEK,AMSTERDAM,NETHERLANDS. NR 37 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 JUL 1 PY 1994 VL 429 IS 1 BP L19 EP & DI 10.1086/187403 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT960 UT WOS:A1994NT96000005 ER PT J AU ABRAMS, MC DAVIS, SP RAO, MLP ENGLEMAN, R BRAULT, JW AF ABRAMS, MC DAVIS, SP RAO, MLP ENGLEMAN, R BRAULT, JW TI HIGH-RESOLUTION FOURIER-TRANSFORM SPECTROSCOPY OF THE MEINEL SYSTEM OF OH SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE LABORATORY SPECTRA; MOLECULAR PROCESSES ID MOLECULAR-CONSTANTS; TERM VALUES; SPECTRUM; LINES; HYDROXYL; EMISSION; STATES; PARAMETERS; ATMOSPHERE; RESONANCE AB The infrared spectrum of the hydroxyl radical OH, between 1850 and 9000 cm-1, has been measured with a Fourier transform spectrometer. The source, a hydrogen-ozone diffusion flame, was designed to study the excitation of rotation-vibration levels of the OH Meinel bands under conditions similar to those in the upper atmosphere which produce the nighttime OH airglow emission. Twenty-three bands were observed: nine bands in the DELTAupsilon = 1 sequence, nine bands in the DELTAupsilon = 2 sequence, and five bands in the DELTAupsilon = 3 sequence. A global nonlinear least-squares fit of 1696 lines yielded molecular parameters with a standard deviation of 0.003 cm-1. Term values are computed, and transition frequencies in the DELTAupsilon = 3, 4, 5, 6 sequences in the near-infrared are predicted. C1 UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. UNIV NEW MEXICO,DEPT CHEM,ALBUQUERQUE,NM 87131. NATL SOLAR OBSERV,TUCSON,AZ 85726. ANDHRA UNIV,WALTAIR 530003,ANDHRA PRADESH,INDIA. RP ABRAMS, MC (reprint author), JET PROP LAB,DIV EARTH & SPACE SCI,MS 183-301,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 29 TC 76 Z9 77 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD JUL PY 1994 VL 93 IS 1 BP 351 EP 395 DI 10.1086/192058 PG 45 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT961 UT WOS:A1994NT96100015 ER PT J AU CHESTER, TJ AF CHESTER, TJ TI THE SEARCH FOR BROWN DWARFS WITH INFRARED SURVEYS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Les Houches School on Science with Astronomical Near-Infrared Sky Surveys CY SEP 20-24, 1993 CL LES HOUCHES SCHOOL, CTR PHYS HOUCHES, LES HOUCHES, FRANCE SP LES HOUCHES SCH, CTR SCI HOUCHES HO LES HOUCHES SCHOOL, CTR PHYS HOUCHES DE BROWN DWARFS; MISSING MASS; 2MASS; NEAR-INFRARED; DENIS AB I compute the maximum number of observable brown dwarfs for various infrared surveys by combining the maximum possible Oort limit (0.1 ''missing'' M.pc-3 with all possible brown dwarf mass and age distributions. This approach shows what limits will be placed on the contribution of brown dwarfs to any possible ''missing mass'' if no brown dwarfs are observed. I consider brown dwarfs with masses of 0.01-0.08 M. and ages of 10(9)-10(10) years. The full range of predicted numbers of brown dwarfs above approximately 6 times the noise of each of the below surveys is: IRAS Point Source Catalog 0.02-6 IRAS Faint Source Catalog \b\ >10-degrees 0.05-16 ISO (2 week 12 mum survey) 0.15-80 SIRTF (2 week 12 mum survey) 2.50-1600 WIRE (4 month 12 mum survey) 21.80-6000 DENIS (half sky) \b\ >10-degrees 0.00-2000 2MASS (full sky) \b\ >10-degrees 0.00-8800 A failure to find brown dwarfs in the IRAS FSC would just barely rule out about half of the mass-age range for Oort limit total masses. A failure to find brown dwarfs in 2MASS/DENIS would rule out roughly the same mass-age range, but would set a limit of 0.1-0.01 times the Oort mass in that mass-age region. No limits would be set for the other half of the mass-age range since both IRAS and 2MASS/DENIS have insufficient sensitivity for brown dwarfs with T < T50 K. A failure to find brown dwarfs with ISO would rule out almost all of the mass-age range for Oort limit total masses, but would not set a significantly lower limit to the brown dwarf mass limit. A failure to find brown dwarfs with SIRTF or WIRE would rule out the entire mass-age range for Oort limit total masses and set an upper limit of 0.1-0.001 times the Oort mass. To date, about 18% of the IRAS FSC has been searched down to 6sigma, and no brown dwarfs have been found. This sets a 95% upper limit of 3 in 18% of the sky, or 13 in the entire FSC for \b\ > 10-degrees. To begin to set useful limits from 2MASS or DENIS, approximately 400 square degrees needs to be analyzed. To date, only a few square degrees of results from the 2MASS prototype camera have been examined, with no brown dwarfs found so far. RP CHESTER, TJ (reprint author), JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91109, USA. NR 7 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 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD JUL PY 1994 VL 217 IS 1-2 BP 69 EP 76 DI 10.1007/BF00990027 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD019 UT WOS:A1994PD01900016 ER PT J AU BEICHMAN, CA JARRETT, T AF BEICHMAN, CA JARRETT, T TI STAR-FORMATION IN TAURUS - PRELIMINARY-RESULTS FROM 2MASS SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Les Houches School on Science with Astronomical Near-Infrared Sky Surveys CY SEP 20-24, 1993 CL LES HOUCHES SCHOOL, CTR PHYS HOUCHES, LES HOUCHES, FRANCE SP LES HOUCHES SCH, CTR SCI HOUCHES HO LES HOUCHES SCHOOL, CTR PHYS HOUCHES DE STAR FORMATION; TAURUS; 2MASS; NEAR-INFRARED ID AURIGA MOLECULAR CLOUD; DENSE CORES; IMAGES AB Data with the 2MASS prototype camera were obtained in a 2.3 sq. deg region in Taurus containing Heiles Cloud 2, a region known from IRAS observations to contain a number of very young solar type stars. Data at 1.25 (J), 1.65 (H), and 2.2 (K(s)) mum are presented. These data are representative of the type and quality of data expected from the planned near-IR surveys, 2MASS and DENIS. Near-IR surveys will be useful for determining the large scale variation of extinction with clouds, for determining the luminosity function in nearby clouds down to ranges of 0.1-1.0 L., and for finding highly extincted T Tauri stars missed by IRAS because the bulk of their luminosity is emitted shortward of 12 mum. RP BEICHMAN, CA (reprint author), JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91109, USA. NR 17 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 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD JUL PY 1994 VL 217 IS 1-2 BP 207 EP 216 DI 10.1007/BF00990056 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD019 UT WOS:A1994PD01900045 ER PT J AU STROM, KM NORDH, L DWEK, E AF STROM, KM NORDH, L DWEK, E TI DISCUSSION SESSION ON STAR-FORMATION, MOLECULAR CLOUDS AND THE INTERSTELLAR-MEDIUM SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT Les Houches School on Science with Astronomical Near-Infrared Sky Surveys CY SEP 20-24, 1993 CL LES HOUCHES SCHOOL, CTR PHYS HOUCHES, LES HOUCHES, FRANCE SP LES HOUCHES SCH, CTR SCI HOUCHES HO LES HOUCHES SCHOOL, CTR PHYS HOUCHES DE STARS; FORMATION; STARS; PRE-MAIN-SEQUENCE; CIRCUMSTELLAR MATTER; INFRARED; STARS ID EVOLUTION AB In this panel discussion contributions were made by K. Strom, L. Nordh and H. Zinnecker on the contributions of surveys to the study of star formation regions, by B. Burton on a survey of galactic H I and by E. Dwek on the detection of galactic supernovae by infrared surveys. The contributions of K. Strom, L. Nordh and E. Dwek are summarized here. C1 STOCKHOLM OBSERV,S-13336 SALTSJOEBADEN,SWEDEN. NASA,GODDARD SPACE FLIGHT CTR,GSFC,GREENBELT,MD 20771. RP STROM, KM (reprint author), UNIV MASSACHUSETTS,ASTRON PROGRAM,AMHERST,MA 01003, USA. NR 4 TC 0 Z9 0 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0004-640X J9 ASTROPHYS SPACE SCI JI Astrophys. Space Sci. PD JUL PY 1994 VL 217 IS 1-2 BP 227 EP 230 DI 10.1007/BF00990060 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PD019 UT WOS:A1994PD01900049 ER PT J AU KUMAR, KV POWELL, MR AF KUMAR, KV POWELL, MR TI SURVIVORSHIP MODELS FOR ESTIMATING THE RISK OF DECOMPRESSION-SICKNESS SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Note ID TIME AB Several approaches have been used for modeling the incidence of decompression sickness (DCS) such as Hill's dose-response and logistic regression. Most of these methods do not include the time-to-onset information in the model. Survival analysis (failure time analysis) is appropriate when the time to onset of an event is of interest. The applicability of survival analysis for modeling the risk of DCS is illustrated by using data obtained from hypobaric chamber exposures simulating extravehicular activities (n = 426). Univariate analysis of incidence-free survival proportions were obtained for Doppler detectable circulating microbubbles (CMB), symptoms of DCS and test aborts. A log-linear failure time regression model with 360 min half-time tissue ratio (TR) as covariate was constructed, and estimated probabilities for various TR values were calculated. Further regression analysis by including CMB status in this model showed significant improvement (p < 0.05) in the estimation of DCS over the previous model. Since DCS is dependent on the exposure pressure as well as the duration of exposure, we recommend the use of survival analysis for modeling the risk of DCS. C1 NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,HOUSTON,TX 77058. RP KUMAR, KV (reprint author), KRUG LIFE SCI,ENVIRONM PHYSIOL LAB,1290 HERCULES DR,SUITE 120,HOUSTON,TX 77058, USA. NR 15 TC 10 Z9 13 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 JUL PY 1994 VL 65 IS 7 BP 661 EP 665 PG 5 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA NV856 UT WOS:A1994NV85600012 PM 7945136 ER PT J AU CONNORS, MM HARRISON, AA SUMMIT, J AF CONNORS, MM HARRISON, AA SUMMIT, J TI CREW SYSTEMS - INTEGRATING HUMAN AND TECHNICAL SUBSYSTEMS FOR THE EXPLORATION OF SPACE SO BEHAVIORAL SCIENCE LA English DT Review DE ALL SUBSYSTEMS; CREW SYSTEMS; GROUP; HUMAN FACTORS; INTELLIGENT SYSTEMS; MAN-MACHINE SYSTEMS; NONLIVING SYSTEMS; TELECOMMUNICATIONS; ASTRONAUTS; GROUP DYNAMICS; INTERGROUP RELATIONS ID MAINTENANCE; PERFORMANCE; SPACEFLIGHT; INTERFACES; COMPUTER; MISSIONS; STATION AB Space exploration missions will require combining human and technical subsystems into overall ''crew systems'' capable of performing under the rigorous conditions of outer space. This report describes substantive and conceptual relationships among humans, intelligent machines, and communication systems, and explores how these components may be combined to complement and strengthen one another. We identify key research issues in the combination of humans and technology and examine the role of individual differences, group processes, and environmental conditions. We conclude that a crew system is, in effect, a social cyborg, a living system consisting of multiple individuals whose capabilities are extended by advanced technology. C1 UNIV CALIF DAVIS,COLL LETTERS & SCI,DAVIS,CA 95616. RP CONNORS, MM (reprint author), NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MOFFETT FIELD,CA 94035, USA. NR 117 TC 4 Z9 4 U1 0 U2 1 PU INT SOC SYSTEMS SCIENCE PI BALTIMORE PA 428 EAST PRESTON ST, BALTIMORE, MD 21202 SN 0005-7940 J9 BEHAV SCI JI Behav. Sci. PD JUL PY 1994 VL 39 IS 3 BP 183 EP 212 DI 10.1002/bs.3830390303 PG 30 WC Psychology; Social Sciences, Interdisciplinary SC Psychology; Social Sciences - Other Topics GA NU165 UT WOS:A1994NU16500002 PM 8060292 ER PT J AU RENAUD, ML CARPENTER, JA AF RENAUD, ML CARPENTER, JA TI MOVEMENTS AND SUBMERGENCE PATTERNS OF LOGGERHEAD TURTLES (CARETTA-CARETTA) IN THE GULF-OF-MEXICO DETERMINED THROUGH SATELLITE TELEMETRY SO BULLETIN OF MARINE SCIENCE LA English DT Article ID RADIO-TELEMETRY; TRACKING; GREEN AB Four loggerhead sea turtles, ranging from 56 to 93 cm in straight carapace length and from 28 to 98 kg in weight, were released in 18- to 78-m water depths and tracked for periods of 5.0 to 10.5 months in the Gulf of Mexico. Home ranges extended from 954 to 28833 km(2) while core areas varied from 89.6 to 4,279 km(2). Core areas included several petroleum and gas structures that may have been visited on a daily, weekly or monthly basis. Average submergence times of loggerheads ranged from 4.2 min in June to 171.7 min in January. The number of submergences per day was inversely proportional to the duration of submergences per day. Loggerheads spent, on the average, over 90% of their time under water in any given season. Bottom depth location of the loggerheads was significantly correlated to Galveston's mean air temperature (-0.56 < r < 0.28) and mean sea surface temperature (-0.72 < r < 0.25). Correlation was higher (-0.58 < r < 0.60) when temperatures were regressed against distance from shore. Mean swimming speeds of these loggerheads were from 0.4 to 1.4 km.h(-1), with over 95% of the values <5 km.h(-1). RP RENAUD, ML (reprint author), NOAA,SE FISHERIES CTR,NATL MARINE FISHERIES SERV,GALVESTON LAB,4700 AVE U,GALVESTON,TX 77551, USA. NR 40 TC 59 Z9 66 U1 1 U2 5 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD JUL PY 1994 VL 55 IS 1 BP 1 EP 15 PG 15 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA PG799 UT WOS:A1994PG79900001 ER PT J AU NEGRI, AJ ADLER, RF NELKIN, EJ HUFFMAN, GJ AF NEGRI, AJ ADLER, RF NELKIN, EJ HUFFMAN, GJ TI REGIONAL RAINFALL CLIMATOLOGIES DERIVED FROM SPECIAL SENSOR MICROWAVE IMAGER (SSM/I) DATA SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID UNITED-STATES; PRECIPITATION; SATELLITE; CLOUD AB Climatologies of convective precipitation were derived from passive microwave observations from the Special Sensor Microwave Imager using a scattering-based algorithm of Adler et al. Data were aggregated over periods of 3-5 months using data from 4 to 5 years. Data were also stratified by satellite overpass times (primarily 0600 and 1800 local time). Four regions [Mexico, Amazonia, western Africa, and the western equatorial Pacific Ocean (TOGA COARE area)] were chosen for their meteorological interest and relative paucity of conventional observations. The strong diurnal variation over Mexico and the southern United States was the most striking aspect of the climatologies. Pronounced morning maxima occurred offshore, often in concavities in the coastline, the result of the increased convergence caused by the coastline shape. The major feature of the evening rain field was a linear-shaped maximum along the western slope of the Sierra Madre Occidental. Topography exerted a strong control on the rainfall in other areas, particularly near the Nicaragua/Honduras border and in Guatemala, where maxima in excess of 700 mm month-1 were located adjacent to local maxima in terrain. The correlation between the estimates and monthly gage data over the southern United States was low (0.45), due mainly to poor temporal sampling in any month and an inadequate sampling of the diurnal cycle. Over the Amazon Basin the differences in morning versus evening rainfall were complex, with an alternating series of morning/evening maxima aligned southwest to northeast from the Andes to the northeast Brazilian coast. Areal extent of rainfall in Amazonia was slightly higher in the evening, but a maximum in morning precipitation was found on the Amazon River just east of Manaus. Precipitation over the water in the ITCZ north of Brazil was more pronounced in the morning, and a pronounced land- /sea-breeze circulation was found along the northeast coast of Brazil. Inter-comparison of four years revealed 1992 to be the driest over Amazonia, with about a 23% decrease in mean rain rate compared to the 4-year mean estimated rain rate. The major rain feature of tropical western Africa was found on the west coast-a pronounced overland evening maximum directly between the coast and a high mountain peak, and a morning maximum directly off shore. An intense, localized morning maximum of over 1 000 mm month-1 was found at a concavity in the coast at the Bight of Bonny. In the region of the TOGA COARE experiment, precipitation in the ITCZ was greater in November 1989 February 1990, compared to the same period in 1988-1989, notably in the region five degrees either side of the equator from 160-degrees-E to the dateline. There was a clear preference in both seasons for morning precipitation over the water. Interesting diurnal effects were found over and offshore of New Guinea and the Solomon Islands. For the eight months studied, averaging both the gauges and Goddard Scattering Algorithm estimates to 2.5-degrees grid boxes yielded a correlation of 0.73, bias of -59.5 mm, and a root-mean-square difference of 131.8 mm-29% and 64%, respectively, of the mean monthly observed rainfall. C1 SCI SYST & APPLICAT INC,LANHAM,MD. RP NEGRI, AJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Huffman, George/F-4494-2014 OI Huffman, George/0000-0003-3858-8308 NR 20 TC 65 Z9 65 U1 0 U2 2 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 JUL PY 1994 VL 75 IS 7 BP 1165 EP 1182 DI 10.1175/1520-0477(1994)075<1165:RRCDFS>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NY828 UT WOS:A1994NY82800001 ER PT J AU ATLAS, D BLACK, PG AF ATLAS, D BLACK, PG TI THE EVOLUTION OF CONVECTIVE STORMS FROM THEIR FOOTPRINTS ON THE SEA AS VIEWED BY SYNTHETIC-APERTURE RADAR FROM SPACE SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID OCEAN-ATMOSPHERE MODEL; NORTH-ATLANTIC OCEAN; CIRCULATION; BRAZIL; ICE AB SEASAT synthetic aperture radar (SAR) echoes from the sea have previously been shown to be the result of rain and winds produced by convective storms; rain damps the surface waves and causes echo-free holes, while the diverging winds associated with the downdraft generate waves and associated echoes surrounding the holes. Gust fronts are also evident. Such a snapshot from 8 July 1978 has been examined in conjunction with ground-based radar. This leads to the conclusion that the SAR storm footprints resulted f rom storm processes that occurred up to an hour or more prior to the snapshot. A sequence of events is discerned from the SAR imagery in which new cell growth is triggered in between the converging outflows of two preexisting cells. In turn, the new cell generates a mini-squall line along its expanding gust front. While such phenomena are well known over land, the spaceborne SAR now allows important inferences to be made about the nature and frequency of convective storms over the oceans. The storm effects on the sea have significant implications for spaceborne wind scatterometry and rainfall measurements. Some of the findings herein remain speculative because of the great distance to the Miami weather radar-the only source of corroborative data. C1 NOAA,ATLANTIC OCEANOG & METEOROL,DIV HURRICANE RES,CORAL GABLES,FL 33146. RP ATLAS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 9102,GREENBELT,MD 20771, USA. NR 21 TC 21 Z9 21 U1 2 U2 2 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 JUL PY 1994 VL 75 IS 7 BP 1183 EP 1199 DI 10.1175/1520-0477(1994)075<1183:TEOCSF>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NY828 UT WOS:A1994NY82800002 ER PT J AU HALLS, HC PALMER, HC BATES, MP PHINNEY, WC AF HALLS, HC PALMER, HC BATES, MP PHINNEY, WC TI CONSTRAINTS ON THE NATURE OF THE KAPUSKASING STRUCTURAL ZONE FROM THE STUDY OF PROTEROZOIC DYKE SWARMS SO CANADIAN JOURNAL OF EARTH SCIENCES LA English DT Article ID POLAR WANDER PATH; HEARST DIKE SWARM; SUPERIOR-PROVINCE; NORTHERN ONTARIO; MATACHEWAN DYKES; TECTONIC HISTORY; UPLIFT HISTORY; PALEOMAGNETISM; CANADA; EVOLUTION AB Petrochemical, paleomagnetic, and structural studies on Early Proterozoic dyke swarms show that the rocks of the Kapuskasing structural zone (KSZ), central Superior Province, were upthrust about 10-15 km along the Ivanhoe Lake fault after intrusion of 2.04 Ga Kapuskasing dykes. This uplift was part of a more widespread deformation in flanking terranes that involved sinistral motion along north-north-northwest-trending faults, dextral displacement along east-northeast-northeast-trending faults, and a distortion of the 2.45 Ga Matachewan swarm to the west and northwest of the Ivanhoe Lake fault. The most spectacular demonstration that the KSZ is largely a product of Proterozoic deformation is that Matachewan dykes change their magnetic polarity on crossing the zone, a consequence of remanence acquisition at deep crustal levels being delayed until after a reversal of the earth's magnetic field and prior to uplift of the dykes. Matachewan and Kapuskasing dykes within the amphibolite- to granulite-grade rocks of the KSZ are relatively fresh and contain a high-alumina green amphibole and feldspar laths that exhibit tea-coloured clouding due to the presence of submicroscopic inclusions of magnetite. These features may be diagnostic of crystallization at deeper crustal levels because they are found in regions where Rb-Sr biotite ages from tonalites suggest broad-scale uplift of the crust after about 2 Ga, About 50 km west of the KSZ, dykes exhibiting clouded feldspar and high-alumina amphiboles occur on the upthrown side of the Budd Lake fault zone, which has a trend similar to that of the Ivanhoe Lake fault. Therefore a second thrust block may exist, raising the possibility that the KSZ represents the basal member of a series of imbricate thrust slices that extends westwards from the Ivanhoe Lake fault. Radiometric age data suggest that the region affected by this Early Proterozoic deformation continues to the northwest for a further 300 km. C1 UNIV WESTERN ONTARIO, DEPT EARTH SCI, LONDON N6A 5B7, ON, CANADA. UNIV ZIMBABWE, DEPT PHYS, HARARE, ZIMBABWE. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP HALLS, HC (reprint author), UNIV TORONTO, DEPT GEOL, J TUZO WILSON LABS, ERINDALE CAMPUS, MISSISSAUGA L5L 1C6, ON, CANADA. NR 59 TC 34 Z9 34 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 0008-4077 EI 1480-3313 J9 CAN J EARTH SCI JI Can. J. Earth Sci. PD JUL PY 1994 VL 31 IS 7 BP 1182 EP 1196 DI 10.1139/e94-104 PG 15 WC Geosciences, Multidisciplinary SC Geology GA PJ580 UT WOS:A1994PJ58000014 ER PT J AU LANGHOFF, SR BAUSCHLICHER, CW PARTRIDGE, H AF LANGHOFF, SR BAUSCHLICHER, CW PARTRIDGE, H TI THEORETICAL DIPOLE-MOMENT FOR THE X(2)PI STATE OF NO SO CHEMICAL PHYSICS LETTERS LA English DT Article ID NITRIC-OXIDE; BASIS-SETS; LASER AB The dipole moment function for the X 2PI state of NO is studied as a function of the completeness in both the one- and n-particle spaces. Einstein coefficients are presented that are significantly more accurate than previous tabulations for the higher vibrational levels. The theoretical values give considerable insight into the limitations of recently published ratios of Einstein coefficients measured by spectrally resolved infrared chemiluminescence. RP LANGHOFF, SR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 23 TC 45 Z9 45 U1 1 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUL 1 PY 1994 VL 223 IS 5-6 BP 416 EP 422 DI 10.1016/0009-2614(94)00501-X PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NV635 UT WOS:A1994NV63500004 ER PT J AU LEE, TJ AF LEE, TJ TI A COUPLED-CLUSTER STUDY OF XON (X=H, F, CL), AND THE XON[--]XNO TRANSITION-STATES SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CONNECTED TRIPLE EXCITATIONS; NITROSYL FLUORIDE; VIBRATIONAL FREQUENCIES; PERTURBATION-THEORY; AB-INITIO; IMPLEMENTATION; 5TH-ORDER; PROTONATION; GRADIENTS; ABINITIO AB The XON molecules (X=H, F, and Cl) have been studied using the CCSD(T) method. Equilibrium geometries, dipole moments, harmonic frequencies and infrared intensities are predicted. The X-O bond distance is shown to be abnormally long for X=F and Cl, which is attributed to the degree of ionic bonding and the stability of NO+. Stability of the XON molecule relative to the XNO isomer is shown to increase in the order HON < FON < ClON, although even ClON is 27.7 +/- 0.9 kcal/mol (0 K) less stable than ClNO. The XON reversible XNO transition states are also investigated. FON and ClON possess the lowest barrier heights, but these are sufficiently large that isomerization should not be rapid at low temperatures. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Lee, Timothy/K-2838-2012 NR 32 TC 22 Z9 22 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 JUL 1 PY 1994 VL 223 IS 5-6 BP 431 EP 438 DI 10.1016/0009-2614(94)00498-6 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NV635 UT WOS:A1994NV63500006 ER PT J AU FRANCISCO, JS SANDER, SP AF FRANCISCO, JS SANDER, SP TI A COMPUTATIONAL EVALUATION OF THE STRUCTURE AND HEAT OF FORMATION FOR FOCL AND CL2O SO CHEMICAL PHYSICS LETTERS LA English DT Article ID MOLECULAR-ENERGIES; RADICALS AB The structure of FOCl and Cl2O have been investigated using state-of-the-art ab initio methods. Electron correlation methods that have been used are second-order Moller-Plesset perturbation theory, configuration interaction with single and double excitations (CISD), singles and doubles coupled-cluster theory (CCSD), and quadratic configuration interaction with single and double excitation along with perturbative corrections for triple excitation (QCISD(T)). The equilibrium structure has been determined for FOCl and Cl2O. The heat of formation for Cl2O is estimated as 19.3 +/- 2 kcal mol-1 and compares well with the experimental determinations; for FOCl it is 13.4 +/- 2 kcal mol-1 at 298 K. There is a major discrepancy between the theoretical estimate of the heat of formation of FOCl and that determined experimentally from electron-impact/mass spectrometry. RP FRANCISCO, JS (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 16 TC 7 Z9 7 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD JUL 1 PY 1994 VL 223 IS 5-6 BP 439 EP 444 DI 10.1016/0009-2614(94)00486-2 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NV635 UT WOS:A1994NV63500007 ER PT J AU NOEVER, DA MATSOS, HC CRONISE, RJ LOOGER, LL RELWANI, RA NIKORA, VI AF NOEVER, DA MATSOS, HC CRONISE, RJ LOOGER, LL RELWANI, RA NIKORA, VI TI OCEAN-ATMOSPHERE CO2 EXCHANGE - AN ACCESSIBLE LAB SIMULATION FOR CONSIDERING BIOLOGICAL EFFECTS SO CLIMATIC CHANGE LA English DT Article ID BIOCONVECTION PATTERNS; GYROTACTIC MICROORGANISMS; DYNAMICS; SUSPENSION; GROWTH; CELLS AB Phytoplankton is considered a key component mediating the ocean-atmospheric exchange of carbon dioxide and oxygen. Lab simulations which model biological responses to atmospheric change are difficult to translate into natural settings owing in part to the vertical migration of phytoplankton. In the sea this vertical migration acts to regulate actual carbon dioxide consumption. To capture some critical properties of this vertical material transfer, we monitored the effects of atmospheric CO2 on dense suspensions of bioconvecting microorganisms. Bioconvection refers to the spontaneous patterns of circulation which arise among such upwardly swimming cells as alga, protozoa, zoospore and large bacteria. Gravity, phototaxis and chemotaxis have all been implicated as affecting pattern-forming ability. The ability of a biologically active suspension to detect atmospheric changes offers a unique method to quantify organism adjustment and vertical migration. With increasing CO2, bioconvection patterns in alga (P. parva) and protozoa (T. pyriformis) lose their robustness, and surface cell populations retreat from the highest CO2 regions. Cell movement (both percent motile and mean velocity) generally diminishes. A general program of image analysis yields statistically significant variations in macroscopic migration patterns; both fractal dimension and various crystallographic parameters correlate strongly with carbon dioxide content. C1 ACAD SCI MOLDAVIAN SSR,INST GEOPHYS & GEOL,KISHINEV,MOLDOVA. RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES 76,HUNTSVILLE,AL 35812, USA. NR 34 TC 4 Z9 4 U1 1 U2 2 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0165-0009 J9 CLIMATIC CHANGE JI Clim. Change PD JUL PY 1994 VL 27 IS 3 BP 299 EP 320 DI 10.1007/BF01094292 PG 22 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA NV411 UT WOS:A1994NV41100004 ER PT J AU FICHOT, F HARSTAD, K BELLAN, J AF FICHOT, F HARSTAD, K BELLAN, J TI UNSTEADY EVAPORATION AND COMBUSTION OF A DROP CLUSTER INSIDE A VORTEX SO COMBUSTION AND FLAME LA English DT Article ID FLAMES; FLOWS AB A model has been developed that describes the evaporation, ignition. and combustion of a drop cluster embedded in a large vortex. The purpose of this model is to simulate the behavior of drops in large coherent vortices produced in the shear layer of a jet. The model treats the dynamic interactions between the drops and the vortex, and also takes into account the drop proximity to calculate the heat and mass transfer between drops and ambient gas. The gas phase outside the cluster is treated as an unsteady, reacting phase, whereas quasi-steadiness is assumed between the drops and surrounding gas inside the cluster. It is assumed that drops will not burn individually, but as a group. The results show a very complex interaction between the dynamics of the drop-loaded vortex, the flame, and the evaporation process. A quasi-steady state is not always reached, depending upon the drop number density or the vortex intensity. In most cases, the flame is located very close to the cluster. The mass ratio of burned fuel (at complete evaporation) to initial fuel is generally less than 10%. C1 JET PROP LAB,PASADENA,CA 91109. NR 20 TC 6 Z9 6 U1 0 U2 0 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 JUL PY 1994 VL 98 IS 1-2 BP 5 EP 19 DI 10.1016/0010-2180(94)90194-5 PG 15 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA NU722 UT WOS:A1994NU72200002 ER PT J AU GLOBUS, A RAIBLE, E AF GLOBUS, A RAIBLE, E TI 14 WAYS TO SAY NOTHING WITH SCIENTIFIC VISUALIZATION SO COMPUTER LA English DT Article AB Scientific visualization can be used to produce beautiful pictures. Those not properly initiated into the mysteries of visualization research often fail to appreciate the artistic qualities of these images and needlessly seek to Understand the data from which they are derived. This article describes a number of effective techniques to confound such pernicious activity. The authors accumulated this collection of rules from the scientific visualization literature and from numerous presentations they have both given and attended. The whole point, according to the authors, is to make this set of techniques available so that attention can be diverted away from data and toward beauty. They claim that if you follow these rules to the letter, you'll never need to compromise your pretty pictures with the mundane realities of science. RP GLOBUS, A (reprint author), NASA,AMES RES CTR,COMP SCI CORP,MS 27A,MOFFETT FIELD,CA 94035, USA. NR 6 TC 5 Z9 5 U1 0 U2 2 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0018-9162 J9 COMPUTER JI Computer PD JUL PY 1994 VL 27 IS 7 BP 86 EP 88 DI 10.1109/2.299418 PG 3 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA NW997 UT WOS:A1994NW99700019 ER PT J AU PADGETT, ML KARPLUS, WJ DEISS, S SHELTON, R AF PADGETT, ML KARPLUS, WJ DEISS, S SHELTON, R TI COMPUTATIONAL INTELLIGENCE STANDARDS - MOTIVATION, CURRENT ACTIVITIES AND PROGRESS SO COMPUTER STANDARDS & INTERFACES LA English DT Article DE TERMINOLOGY; ARTIFICIAL NEURAL NETWORKS; SPECIFICATION; VIRTUAL REALITY ID NEURAL NETWORKS; PATTERN-RECOGNITION; MODEL; NEOCOGNITRON; SIMULATION AB Computational Intelligence is an emerging technology of keen interest to the developers of computer standards and interfaces. Coherent communications among the diverse set of users of computational AI is necessary for the protection of all parties and can help further the serious development of artificial neural networks, fuzzy systems, evolutionary programming and virtual reality. Current activities of the IEEE Neural Networks Council Standards Committee encompass all these areas, emphasizing the development of glossaries and symbologies, performance measures and interface standards for these interrelated fields. Progress toward these goals is described in this paper. C1 AUBURN UNIV, DEPT ELECT ENGN, AUBURN, AL 36830 USA. UNIV CALIF LOS ANGELES, DEPT COMP SCI, LOS ANGELES, CA 90024 USA. APPL NEURODYNAM, ENCINITAS, CA 92024 USA. NASA, JSC, SOFTWARE TECHNOL BRANCH, HOUSTON, TX 77058 USA. NR 98 TC 2 Z9 2 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0920-5489 EI 1872-7018 J9 COMPUT STAND INTER JI Comput. Stand. Interfaces PD JUL PY 1994 VL 16 IS 3 BP 185 EP 203 DI 10.1016/0920-5489(94)90011-6 PG 19 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering SC Computer Science GA NW172 UT WOS:A1994NW17200003 ER PT J AU MOUNT, DM NETANYAHU, NS AF MOUNT, DM NETANYAHU, NS TI COMPUTATIONALLY EFFICIENT ALGORITHMS FOR HIGH-DIMENSIONAL ROBUST ESTIMATORS SO CVGIP-GRAPHICAL MODELS AND IMAGE PROCESSING LA English DT Article ID HIGH BREAKDOWN-POINT; CIRCULAR ARC CENTER; SQUARES REGRESSION; GEOMETRIC DUALITY; SLOPE SELECTION; TIME ALGORITHM; LINEAR-TIME; RADIUS; POWER AB Given a set of n distinct points in d-dimensional space that are hypothesized to lie on a hyperplane, robust statistical estimators have been recently proposed for the parameters of the model that best fits these points. This paper presents efficient algorithms for computing median-based robust estimators (e.g., the Theil-Sen and repeated median (RM) estimators) in high-dimensional space. We briefly review basic computational geometry techniques that were used to achieve efficient algorithms in the 2-D case. Then generalization of these techniques to higher dimensions is introduced. Geometric observations are followed by a presentation of O(n(d-1) log n) expected time algorithms for the d-dimensional Theil-Sen and RM estimators. Both algorithms are space optimal; i.e., they require O(n) storage, for fixed d. Finally, an extension of the methodology to nonlinear domain(s) is demonstrated. (c) 1994 Academic Press, Inc. C1 UNIV MARYLAND,INST ADV COMP STUDIES,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GODDARD SPACE & FLIGHT CTR,DIV SPACE DATA & COMP,GREENBELT,MD 20771. UNIV MARYLAND,CTR AUTOMAT RES,COMP VIS LAB,COLLEGE PK,MD 20742. RP MOUNT, DM (reprint author), UNIV MARYLAND,DEPT COMP SCI,COLLEGE PK,MD 20742, USA. NR 47 TC 5 Z9 5 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 1049-9652 J9 CVGIP-GRAPH MODEL IM PD JUL PY 1994 VL 56 IS 4 BP 289 EP 303 PG 15 WC Computer Science, Software Engineering SC Computer Science GA PD303 UT WOS:A1994PD30300002 ER PT J AU AMUNDSON, R WANG, Y CHADWICK, O TRUMBORE, S MCFADDEN, L MCDONALD, E WELLS, S DENIRO, M AF AMUNDSON, R WANG, Y CHADWICK, O TRUMBORE, S MCFADDEN, L MCDONALD, E WELLS, S DENIRO, M TI FACTORS AND PROCESSES GOVERNING THE C-14 CONTENT OF CARBONATE IN DESERT SOILS SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article ID STABLE ISOTOPE CHEMISTRY; RADIOCARBON MEASUREMENTS; PEDOGENIC CARBONATE; ORGANIC-MATTER; ARID ZONE; AGES; DYNAMICS; CLIMATE; DIOXIDE; NEVADA AB A model is presented describing the factors and processes which determine the measured C-14 ages of soil calcium carbonate. Pedogenic carbonate forms in isotopic equilium with soil CO2. Carbon dioxide in soils is a mixture of CO2 derived from two biological sources: respiration by living plant roots and respiration of microorganisms decomposing soil humus. The relative proportion of these two CO2 Sources can greatly affect the initial C-14 content of pedogenic carbonate: the greater the contribution of humus-derived CO2, the greater the initial C-14 age of the carbonate mineral. For any given mixture Of CO2 Sources, the steady-state (CO2)-C-14 distribution vs. soil depth can be described by a production/diffusion model. As a soil ages, the C-14 age of soil humus increases, as does the steady-state C-14 age of soil CO2 and the initial C-14 age of any pedogenic carbonate which forms. The mean C-14 age of a complete pedogenic carbonate coating or nodule will underestimate the true age of the soil carbonate. This discrepancy increases the older a soil becomes. Partial removal of outer (and younger) carbonate coatings greatly improves the relationship between measured C-14 age and true age. Although the production/diffusion model qualitatively explains the C-14 age of pedogenic carbonate vs. soil depth in many soils, other factors, such as climate change, may contribute to the observed trends, particularily in soils older than the Holocene. C1 UNIV CALIF RIVERSIDE,DEPT EARTH SCI,RIVERSIDE,CA 92521. UNIV CALIF IRVINE,DEPT GEOSCI,IRVINE,CA 92717. UNIV CALIF SANTA BARBARA,DEPT GEOL SCI,SANTA BARBARA,CA 93106. JET PROP LAB,DIV EARTH SCI,PASADENA,CA 91109. UNIV NEW MEXICO,DEPT EARTH & PLANETARY SCI,ALBUQUERQUE,NM 87131. RP AMUNDSON, R (reprint author), UNIV CALIF BERKELEY,DIV ECOSYST SCI,108 HILGARD,BERKELEY,CA 94720, USA. RI Trumbore, Susan/B-1948-2013; Amundson, Ronald /E-2654-2015 NR 45 TC 74 Z9 77 U1 0 U2 8 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD JUL PY 1994 VL 125 IS 1-4 BP 385 EP 405 DI 10.1016/0012-821X(94)90228-3 PG 21 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA PC442 UT WOS:A1994PC44200026 ER PT J AU STEIMLE, FW JEFFRESS, D FROMM, SA REID, RN VITALIANO, JJ FRAME, A AF STEIMLE, FW JEFFRESS, D FROMM, SA REID, RN VITALIANO, JJ FRAME, A TI PREDATOR-PREY RELATIONSHIPS OF WINTER FLOUNDER, PLEURONECTES-AMERICANUS, IN THE NEW-YORK BIGHT APEX SO FISHERY BULLETIN LA English DT Article ID PSEUDOPLEURONECTES-AMERICANUS; MARINE FISHES; FOOD; COMMUNITY; SELECTION; DIET AB A 39-month study of the effects of cessation of sewage sludge disposal in the New York Bight apex on the diets of certain fishes and on the benthic macrofaunal community provided an opportunity to examine predator-prey relationships of winter flounder, pleuronectes americanus, one of the common predators in the area. Benthic macrofauna and winter flounder were collected monthly and bimonthly, respectively, from July 1986 through SePtember 1989 at three sites in the Bight apex that are variably influenced by sewage sludge. There were limited changes in winter flounder diets and abundance of dominant benthic macrofaunal species following cessation of sewage sludge disposal. The comparison of volumetric contribution of common prey in flounder stomachs to potential-prey abundance in benthic samples suggested several relationships- These included evidence of preferential predation on the polychaete Pherusa affinis; this selective preference may be associated with its high caloric content as well as with its average high biomass density. other common prey, primarily polychaetes but including an anthozoan, were also preyed upon in proportions greater than their abundance in the environment. Some moderately abundant potential prey, such as the small near-surface-dwelling mollusc Nucula proxima and the ribbon worm Cerebratulus lacteus were not commonly preyed upon suggesting they were unavailable as prey or were avoided by winter flounder. Corresponding fluctuations in abundances and predation of the pollution-tolerant polychaete Capitella sp. and the pollution-sensitive amphipod Unciola irrorata suggested a proportional consumption relationship in association with sludge disposal and its cessation. RP STEIMLE, FW (reprint author), NOAA,NATL MARINE FISHERIES SERV,NE FISHERIES SCI CTR,SANDY HOOK LAB,HIGHLANDS,NJ 07732, USA. NR 44 TC 15 Z9 15 U1 1 U2 3 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD JUL PY 1994 VL 92 IS 3 BP 608 EP 619 PG 12 WC Fisheries SC Fisheries GA NX911 UT WOS:A1994NX91100013 ER PT J AU SUMMONS, RE JAHNKE, LL ROKSANDIC, Z AF SUMMONS, RE JAHNKE, LL ROKSANDIC, Z TI CARBON ISOTOPIC FRACTIONATION IN LIPIDS FROM METHANOTROPHIC BACTERIA - RELEVANCE FOR INTERPRETATION OF THE GEOCHEMICAL RECORD OF BIOMARKERS SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID METHYLOCOCCUS-CAPSULATUS BATH; METHANE MONO-OXYGENASE; FATTY-ACID COMPOSITION; METHYL STEROL; PROKARYOTIC TRITERPENOIDS; BIOSYNTHESIS; OXIDATION; HOPANOIDS; SEDIMENTS; MONOOXYGENASE AB Experiments with cultured aerobic methane oxidising bacteria confirm that their biomarker lipids will be significantly depleted in C-13 compared to the substrate. The methanotrophic bacteria Methylococcus capsulatus and Methylomonas methanica, grown on methane and using the RuMP cycle for carbon assimilation, show maximum C-13 fractionation of approximately 30 parts per thousand in the resultant biomass. In M. capsulatus, the maximum fractionation is observed in the earliest part of the exponential growth stage and decreases to approximately 16 parts per thousand as cells approach stationary phase. This change may be associated with a shift from the particulate form to the soluble form of the methane monooxygenase enzyme. Less than maximum fractionation is observed when cells are grown with reduced methane availability. Biomass of M. capsulatus grown on methanol was depleted by 9 parts per thousand compared to the substrate. Additional strong C-13 fractionation takes place during polyisoprenoid biosynthesis in methanotrophs. The deltaC-13 values of individual hopanoid and steroid biomarkers produced by these organisms were as much as 10 parts per thousand more negative than total biomass. In individual cultures, squalene was C-13-enriched by as much as 14 parts per thousand compared to the triterpane skeleton of bacteriohopaneaminopentol. Much of the isotopic dispersion in lipid metabolites could be attributed to shifts in their relative abundances, combined with an overall reduction in fractionation during the growth cycle. In cells grown on methanol, where there was no apparent effect of growth stage on overall fractionation there were still significant isotopic differences between closely related lipids including a 5.3 parts per thousand difference between the hopane and 3beta-methylhopane skeletons. Hopane and sterane polyisoprenoids were also C-13-depleted compared to fatty acids. These observations have significant implications for the interpretation of specific compound isotopic signatures now being measured for hydrocarbons and other lipids present in sediments and petroleum. In particular, biomarker lipids produced by a single organism do not necessarily have the same carbon isotopic composition. C1 NASA,AMES RES CTR,PLANETARY BIOL BRANCH,MOFFETT FIELD,CA 94035. RP SUMMONS, RE (reprint author), AUSTRALIAN GEOL SURVEY ORG,GPO BOX 378,CANBERRA,ACT 2601,AUSTRALIA. NR 54 TC 218 Z9 224 U1 1 U2 49 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 JUL PY 1994 VL 58 IS 13 BP 2853 EP 2863 DI 10.1016/0016-7037(94)90119-8 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NX237 UT WOS:A1994NX23700008 PM 11540111 ER PT J AU MCKAY, G LE, L WAGSTAFF, J CROZAZ, G AF MCKAY, G LE, L WAGSTAFF, J CROZAZ, G TI EXPERIMENTAL PARTITIONING OF RARE-EARTH ELEMENTS AND STRONTIUM - CONSTRAINTS ON PETROGENESIS AND REDOX CONDITIONS DURING CRYSTALLIZATION OF ANTARCTIC ANGRITE LEWIS CLIFF-86010 SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID DOS-REIS METEORITE; DIFFUSION; PETROLOGY AB The partitioning of REE and Sr among anorthite, fassaitic pyroxene, and synthetic melts similar in bulk composition to angrite LEW 86010 was studied experimentally at 1 atm and 1175-1210-degrees-C using the percent level doping technique. Most experiments were at an oxygen fugacity 1 log unit above the iron-wustite buffer, but Eu and Gd partitioning were studied from iron-wustite to just above quartz-fayalite-magnetite. Pyroxene partition coefficients are correlated with Al content of the pyroxene. Despite the fassaitic nature of the synthetic pyroxenes, partition coefficients are not dramatically different from those for diopside. Pyroxene/melt REE partition coefficients range from .08 for La to .45 for Yb. Plagioclase/melt coefficients (except for Eu) range from .022 for La to .004 for Yb. D(Eu) varies by nearly a factor of 2 for pyroxene and nearly a factor of 5 for plagioclase over the four log unit range of fO2 studied. Parent melts calculated by inverting natural pyroxene and anorthite cores from LEW 86010 using partition coefficients from this study are in excellent agreement with one another. This agreement is strong evidence for (1) equilibrium between the natural mineral cores at the time the meteorite crystallized, and (2) lack of subsequent subsolidus diffusive modification of REE abundances in the cores. The overall levels of the computed REE patterns agree well with REE abundances in bulk samples of LEW 86010, supporting the idea that this sample formed through a process approximating closed-system fractional crystallization. The observed variation of D(Eu)/D(Gd) with fO2 for pyroxene and plagioclase was combined with Eu and Gd abundances from mineral cores in LEW 86010 to estimate the oxygen fugacity under which this sample crystallized. Results indicate crystallization at about 1 log unit above iron-wustite, considerably more oxidizing than conditions under which common basaltic achondrites such as eucrites are thought to have formed. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130. WASHINGTON UNIV,MCDONNELL CTR SPACE SCI,ST LOUIS,MO 63130. RP MCKAY, G (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH,SN4,HOUSTON,TX 77058, USA. NR 35 TC 81 Z9 82 U1 0 U2 10 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 JUL PY 1994 VL 58 IS 13 BP 2911 EP 2919 DI 10.1016/0016-7037(94)90124-4 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NX237 UT WOS:A1994NX23700013 ER PT J AU BOGARD, DD GARRISON, DH SHIH, CY NYQUIST, LE AF BOGARD, DD GARRISON, DH SHIH, CY NYQUIST, LE TI AR-39-AR-40 DATING OF 2 LUNAR GRANITES - THE AGE OF COPERNICUS SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID CHRONOLOGY; GEOCHRONOLOGY; PETROLOGY; CLASTS; MOON; CA AB Previous investigations have suggested that KREEP glass found in 12033 and other Apollo 12 soils was ejected from the crater Copernicus and deposited in a ray across this site. Soil fragment 12033,507 has been described as having a core of felsite (granitic) composition with a KREEP-glass shell. Ar-39-Ar-40 dating of a sample of this granite material shows almost complete resetting 800 +/- 15 Ma ago. We interpret this age as giving the most precise determination to date for the formation time of Copernicus. Cosmic ray exposure ages of the granite and associated KREEP glass in soil 12033, about 250 Ma, are much less than the K-Ar age and suggest a complex, postejection burial history. The Ar-39-Ar-40 age of another granite fragment, 14303,204, is determined to be in the range 3.80-3.85 Ga. This age is in agreement with Ar-39-Ar-40 ages determined for a few other lunar granites and is interpreted to represent resetting by a large, basin-forming impact, probably Imbrium. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77258. RP BOGARD, DD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,CODE SN4,HOUSTON,TX 77058, USA. NR 34 TC 27 Z9 29 U1 0 U2 4 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 JUL PY 1994 VL 58 IS 14 BP 3093 EP 3100 DI 10.1016/0016-7037(94)90181-3 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NZ401 UT WOS:A1994NZ40100011 ER PT J AU SHIH, CY NYQUIST, LE BOGARD, DD WIESMANN, H AF SHIH, CY NYQUIST, LE BOGARD, DD WIESMANN, H TI K-CA AND RB-SR DATING OF 2 LUNAR GRANITES - RELATIVE CHRONOMETER RESETTING SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID PARTITION-COEFFICIENTS; AGE; BA; CHRONOLOGY; DIFFUSION; CLAST; NA AB K-Ca and Rb-Sr age determinations were made for lunar granite 12033,576. This small fragment is a subsample of soil particle 12033,507, which was collected subsurface at the north rim of Head Crater. The K-Ca mineral isochron is well-defined and yields an age of 3.62 +/- 0.11 (2sigma) Ga for lambda(K-40) = 0.5543 Ga-1 and an initial Ca-40/Ca-44 of 47.160 +/- 0.006 (2sigma) (normalized to Ca-42/Ca-40 = 0.31221). The Rb-Sr mineral isochron is quite disturbed and yields an imprecise young age of 2.20 +/- 0.65 Ga for lambda(Rb-87) = 0.0139 Ga-1 and a high initial Sr-87/Sr-86 of 0.775 +/- 0.022. Assuming that the granite crystallized approximately 4.0 Ga ago (a modeled formation age), and was shock-heated 0.8 Ga ago (Ar-39-Ar-40 age), the intermediate Rb-Sr and K-Ca ages are interpreted as due to partial resetting by thermal diffusion of strontium and calcium. Diffusion data determined for argon in 12033,507 give a value of D/a2 approximately 1 X 10(-6) s-1 for a heating temperature of 700-degrees-C; at this temperature it would require a time on the order of days to totally degas argon. The required diffusion coefficients, D, for calcium (7 approximately 9 X 10(-13) cm2 s-1) and Sr (approximately 8 X 10(-12) cm2 s-1) that are predicted from the observed age resetting are in good agreement with those determined experimentally in granitic melts. The K-Ca system was about a factor of ten more resistant to resetting than the Rb-Sr system, which in turn was approximately 10 times more resistant to resetting than the K-Ar system. Diffusion data indicate that isotopic exchange of calcium and strontium was responsible for the partial resetting of the K-Ca and Rb-Sr chronometers, rather than elemental exchange of potassium and rubidium among mineral phases. Rb-Sr isotopic data also were obtained for granite 14303,206, a subsample of breccia clast 14303,204, which was collected at the Fra Mauro region about 180 km from the Apollo 12 site. The mineral isochron is quite disturbed and yields an imprecise age of 3.95 +/- 0.38 Ga for X(Rb-87) = 0.01 39 Ga-1 and initial Sr-87/Sr-86 = 0.7046 +/- 0.005 1. The Rb-Sr age is comparable to the previously determined K-Ca age of 4.04 +/- 0.64 Ga. The Rb-Sr and K-Ca ages of this clast are imprecise and are statistically indistinguishable from the well-defined Ar-39-Ar-40 degassing age of 3.83 +/- 0.03 Ga or the Rb-Sr and K-Ca model ages of 4.30 +/- 0.06 Ga and 4.25 +/- 0.12 Ga, respectively. Because these model ages are within error of a reported zircon U-Pb age of 4.31 Ga, we assume this granitic clast crystallized -4.3 Ga ago and was shock-heated approximately 3.83 Ga ago. Using the apparent resetting of the K-Ar, Rb-Sr, and K-Ca isotopic systems, and literature data for relative strontium and calcium diffusivity, we estimate a shock-reheating temperature of approximately 860-degrees-C would be necessary to partially reset the Rb-Sr and K-Ca ages to their nominal values. This reheating temperature is uncertain because of the large errors on the ages, but would be consistent with complete resetting of the K-Ar age and partial resetting of the Rb-Sr and K-Ca ages, if the hot clast was buried under approximately 1 m of the ejecta blanket for approximately 1 day. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP SHIH, CY (reprint author), LOCKHEED ENGN & SCI CO,MAIL CODE C-23,2400 NASA RD 1,HOUSTON,TX 77258, USA. NR 54 TC 24 Z9 26 U1 1 U2 9 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 JUL PY 1994 VL 58 IS 14 BP 3101 EP 3116 DI 10.1016/0016-7037(94)90182-1 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NZ401 UT WOS:A1994NZ40100012 ER PT J AU REDAELLI, G LAIT, LR SCHOEBERL, M NEWMAN, PA VISCONTI, G DALTORIO, A MASCI, F RIZI, V FROIDEVAUX, L WATERS, JW MILLER, AJ AF REDAELLI, G LAIT, LR SCHOEBERL, M NEWMAN, PA VISCONTI, G DALTORIO, A MASCI, F RIZI, V FROIDEVAUX, L WATERS, JW MILLER, AJ TI UARS MLS O3 SOUNDINGS COMPARED WITH LIDAR MEASUREMENTS USING THE CONSERVATIVE COORDINATES RECONSTRUCTION TECHNIQUE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; MICROWAVE LIMB SOUNDER; OZONE; ER-2 AB A technique based on conservative properties of certain meteorological fields is used to compare ozone measurements from the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite (UARS) with soundings from a lidar system operated at midlatitudes by the University of L'Aquila, Italy. A few typical cases are analyzed in connection with the position of the vortex relative to the observing station, and it is shown that in general lidar observations taken within the vortex compare well with the UARS data, regardless of whether they are coincident with a satellite overpass. It is shown that such analysis may be useful for comparing measurements of the same quantity taken at different sites using different measurement techniques. C1 HUGHS STX CORP,LANHAM,MD. IST NAZL GEOFIS,ROME,ITALY. JET PROP LAB,PASADENA,CA 91109. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP REDAELLI, G (reprint author), UNIV LAQUILA,DIPARTIMENTO FIS,VIA VETOIO,I-67010 COPPITO,ITALY. RI Newman, Paul/D-6208-2012; OI Newman, Paul/0000-0003-1139-2508; Redaelli, Gianluca/0000-0002-4449-1513 NR 14 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1994 VL 21 IS 14 BP 1535 EP 1538 DI 10.1029/94GL00629 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NV986 UT WOS:A1994NV98600012 ER PT J AU AHRENS, TJ TAKATA, T OKEEFE, JD ORTON, GS AF AHRENS, TJ TAKATA, T OKEEFE, JD ORTON, GS TI RADIATIVE SIGNATURES FROM IMPACT OF COMET SHOEMAKER-LEVY-9 ON JUPITER SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The visible optical power emitted from the expansion plumes from 0.4 and 2 km diameter fragments of Shoemaker-Levy are expected to be, approximately 25% and comparable to, the visible solar flux reflected from Jupiter, respectively, for several minutes, and could be easily observed by sensors on the Galileo spacecraft. Earth-based observers can detect these plumes as these expand over the SW limb of Jupiter and come into earth view some n-minutes after impact! C1 JET PROP LAB,PASADENA,CA 91109. RP AHRENS, TJ (reprint author), CALTECH,LINDHURST LAB EXPTL GEOPHYS,SEISMOL LAB,SEISMOL 252-21,PASADENA,CA 91125, USA. NR 10 TC 13 Z9 13 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUL 1 PY 1994 VL 21 IS 14 BP 1551 EP 1553 DI 10.1029/94GL01578 PG 3 WC Geosciences, Multidisciplinary SC Geology GA NV986 UT WOS:A1994NV98600016 ER PT J AU STEFFES, PG JENKINS, JM AUSTIN, RS ASMAR, SW LYONS, DT SEALE, EH TYLER, GL AF STEFFES, PG JENKINS, JM AUSTIN, RS ASMAR, SW LYONS, DT SEALE, EH TYLER, GL TI RADIO OCCULTATION STUDIES OF THE VENUS ATMOSPHERE WITH THE MAGELLAN SPACECRAFT .1. EXPERIMENTAL DESCRIPTION AND PERFORMANCE SO ICARUS LA English DT Article AB While primarily designed for radar studies of the Venus surface, the high effective isotropic radiated power (EIRP) from the Magellan spacecraft makes it an ideal transmitter for use in radio occultation measurements of the refractivity and absorptivity of the Venus atmosphere. Such experiments have been conducted involving transmissions at 2.3 GHz and 8.4 GHz (13 cm and 3.6 cm, respectively), during spacecraft ingress. Since the stability of the spacecraft transmitter is critical for accurately determining the Doppler shift and amplitude attenuation created as the ray penetrates the atmosphere, the spacecraft transmitter was locked to a 2.1 GHz uplink from a 70-meter DSN station which also received the signals. Because of the high directivity of the spacecraft antenna, and the significant ray bending in the deep Venus atmosphere, a spacecraft tracking maneuver was designed to keep the spacecraft antenna pointed in the direction of the refracted ray path back to Earth. This tracking maneuver, plus the high EIRP of the Magellan transmitter has yielded 3.6 cm refractivity and absorptivity profiles down to the 35 km altitude and 13 cm profiles down to the altitude of critical refraction (approximately 33 km). The statistical uncertainties in the derived profiles are significantly lower than those previously obtained, resulting in extremely accurate profiles of H2SO4 (g) abundance, as discussed in an accompanying paper by J. M. Jenkins, P. G. Steffes, D. P. Hinson, J. D. Twicken, and G. L. Tyler (1994, Icarus 110, 79-94). (C) 1994 Academic Press, Inc. C1 NASA,AMES RES CTR,INST SETI,MOFFETT FIELD,CA 94035. CALTECH,JET PROP LAB,PASADENA,CA 91109. MARTIN MARIETTA CORP,DENVER,CO 80201. STANFORD UNIV,CTR RADAR ASTRON,STANFORD,CA 94305. RP STEFFES, PG (reprint author), GEORGIA INST TECHNOL,SCH ELECT ENGN,ATLANTA,GA 30332, USA. NR 14 TC 12 Z9 12 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 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1994 VL 110 IS 1 BP 71 EP 78 DI 10.1006/icar.1994.1107 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PG370 UT WOS:A1994PG37000003 ER PT J AU JENKINS, JM STEFFES, PG HINSON, DP TWICKEN, JD TYLER, GL AF JENKINS, JM STEFFES, PG HINSON, DP TWICKEN, JD TYLER, GL TI RADIO OCCULTATION STUDIES OF THE VENUS ATMOSPHERE WITH THE MAGELLAN SPACECRAFT .2. RESULTS FROM THE OCTOBER-1991 EXPERIMENTS SO ICARUS LA English DT Article ID SULFURIC-ACID VAPOR; LABORATORY MEASUREMENTS; SIMULATED CONDITIONS; MIDDLE ATMOSPHERE; ZONAL WINDS; OPACITY; MICROWAVE AB On October 5 and 6, 1991, three dual-frequency ingress radio occultation experiments were conducted at Venus during consecutive orbits of the Magellan spacecraft. The radio signals probed a region of the atmosphere near 65 degrees N, with a solar zenith angle of 108 degrees, reaching below 35 km at 3.6 cm, and below 34 km at 13 cm (above a mean radius of 6052 km). The high effective isotropic radiated power (EIRP) of the Magellan spacecraft and highly successful attitude maneuvers allowed these signals to probe deeper than any previous radio occultation experiment and also resulted in the most accurate thermal and sulfuric acid vapor abundance profiles ever obtained at Venus through radio occultation techniques. The performance of the spacecraft and the experiment design are discussed in an accompanying paper by P. G. Steffes, J. M. Jenkins, R. S. Austin, S. W. Asmar, D. T. Lyons, E. H. Seale, and G. L. Tyler (1994, Icarus 110, 71-78). Average electron density profiles retrieved from the data possess peaks between 2600 and 6000 cm(-3), well below typical values of 10,000 cm(-3) retrieved in 1979 by Pioneer Venus at similar solar zenith angles. Other basic results include vertical profiles of temperature, pressure, and density in the neutral atmosphere, 13- and 3.6-cm absorptivity, and H2SO4(g) abundance below the main cloud layer. H2SO4(g) becomes significant below 50 km, reaching peaks between 18 and 24 ppm near 39 km before dropping precipitously below 38 km. These sharp decreases confirm the thermal decomposition of sulfuric acid vapor below 39 km. Since the Venus atmosphere rotated approximately 10 degrees between experiments, the data contain information about the horizontal variability of the atmosphere. All derived profiles exhibit significant variations from orbit to orbit, indicating the presence of dynamical processes between 33 and 200 km. In particular, the orbit-to-orbit variations in temperature and in H2SO4(g) abundance appear to be correlated, suggesting that a common mechanism may be responsible for the observed spatial variations. (C) 1994 Academic Press, Inc. C1 GEORGIA INST TECHNOL,SCH ELECT & COMP ENGN,ATLANTA,GA 30332. STANFORD UNIV,CTR RADAR ASTRON,STANFORD,CA 94305. RP JENKINS, JM (reprint author), NASA,AMES RES CTR,INST SETI,MS 24411,MOFFETT FIELD,CA 94035, USA. NR 34 TC 58 Z9 58 U1 1 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 JUL PY 1994 VL 110 IS 1 BP 79 EP 94 DI 10.1006/icar.1994.1108 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PG370 UT WOS:A1994PG37000004 ER PT J AU WARD, WR HAHN, JM AF WARD, WR HAHN, JM TI DAMPING OF ORBITAL INCLINATIONS BY BENDING WAVES SO ICARUS LA English DT Article ID SOLAR GRAVITATIONAL-FIELD; SATURNS RINGS; DENSITY WAVES; PLANETESIMALS; DISK; EXCITATION; EVOLUTION; ACCRETION; LINDBLAD; SYSTEMS AB An inclined secondary orbiting in a disk will launch bending waves from resonance sites where the Doppler shifted forcing frequency matches the disk's natural frequency for vertical oscillations. These vertical resonances are of two types: external resonances falling interior and exterior to the perturber's semimajor axis that excite its inclination and coorbiting resonances that fall at the perturber's orbit and damp its inclination. We show that torques from coorbiting resonances dominate the bending wave interaction for a constant density disk. In this case the inclination ultimately decays and an estimate of the characteristic time scale for this process is made. (C) 1994 Academic Press, Inc. C1 UNIV NOTRE DAME,DEPT PHYS,NOTRE DAME,IN 46556. SAN JUAN CAPISTRANO RES INST,SAN JUAN CAPISTRANO,CA 92675. RP WARD, WR (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 53 TC 18 Z9 18 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD JUL PY 1994 VL 110 IS 1 BP 95 EP 108 DI 10.1006/icar.1994.1109 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PG370 UT WOS:A1994PG37000005 ER PT J AU IVANCIC, WD SHALKHAUSER, MJ QUINTANA, JA AF IVANCIC, WD SHALKHAUSER, MJ QUINTANA, JA TI A NETWORK ARCHITECTURE FOR A GEOSTATIONARY COMMUNICATION SATELLITE SO IEEE COMMUNICATIONS MAGAZINE LA English DT Article RP IVANCIC, WD (reprint author), NASA,LEWIS RES CTR,DIV SPACE ELECTR,DIGITAL TECHNOL BRANCH,CLEVELAND,OH 44135, USA. NR 32 TC 3 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0163-6804 J9 IEEE COMMUN MAG JI IEEE Commun. Mag. PD JUL PY 1994 VL 32 IS 7 BP 72 EP 84 DI 10.1109/35.295950 PG 13 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA NW851 UT WOS:A1994NW85100008 ER PT J AU WHITMAN, S HANSEN, CD CROCKETT, TW AF WHITMAN, S HANSEN, CD CROCKETT, TW TI RECENT DEVELOPMENTS IN PARALLEL RENDERING SO IEEE COMPUTER GRAPHICS AND APPLICATIONS LA English DT Article C1 LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87544. NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. RP WHITMAN, S (reprint author), DAVID SARNOFF RES CTR,CN 5300,PRINCETON,NJ 08543, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0272-1716 J9 IEEE COMPUT GRAPH JI IEEE Comput. Graph. Appl. PD JUL PY 1994 VL 14 IS 4 BP 21 EP 22 PG 2 WC Computer Science, Software Engineering SC Computer Science GA NV002 UT WOS:A1994NV00200009 ER PT J AU MA, KL PAINTER, JS HANSEN, CD KROGH, MF AF MA, KL PAINTER, JS HANSEN, CD KROGH, MF TI PARALLEL VOLUME RENDERING USING BINARY-SWAP COMPOSITING SO IEEE COMPUTER GRAPHICS AND APPLICATIONS LA English DT Article C1 LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87544. RP MA, KL (reprint author), NASA,LANGLEY RES CTR,ICASE,MS 132C,HAMPTON,VA 23681, USA. NR 13 TC 111 Z9 128 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 JUL PY 1994 VL 14 IS 4 BP 59 EP 68 DI 10.1109/38.291532 PG 10 WC Computer Science, Software Engineering SC Computer Science GA NV002 UT WOS:A1994NV00200014 ER PT J AU SELKER, MD AFZAL, RS REICHERT, P AF SELKER, MD AFZAL, RS REICHERT, P TI A PULSE TRANSMISSION MODE Q-SWITCHED ND-YLF LASER-PUMPED BY CYLINDRICAL MICROLENS-COLLIMATED DIODE BARS SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article ID ARRAY AB A Q-switched cavity-dumped single-transverse-mode Nd:YLF laser pumped by two 60-W quasi-CW diode bars collimated using cylindrical microlens technology produced 4-mJ, 4.5-ns pulses. The pump geometry employed has many of the advantages of longitudinal pumping yet allows the use of high-power quasi-CW bars while requiring only 1 optical element. C1 NASA,GODDARD SPACE FLIGHT CTR,EXPTL INSTRUMENTAT BRANCH,GREENBELT,MD 20771. LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. RP SELKER, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PHOTON BRANCH,CODE 715,GREENBELT,MD 20771, USA. NR 20 TC 14 Z9 15 U1 1 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD JUL PY 1994 VL 30 IS 7 BP 1616 EP 1622 DI 10.1109/3.299493 PG 7 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA NY998 UT WOS:A1994NY99800013 ER PT J AU KORMANYOS, BK REBEIZ, GM AF KORMANYOS, BK REBEIZ, GM TI 20-GHZ POWER COMBINING SLOT-OSCILLATOR ARRAY SO IEEE MICROWAVE AND GUIDED WAVE LETTERS LA English DT Article AB A four-element power-combining array of quasi-optical dot oscillators has been constructed at 20 GHz. The array is placed on a dielectric substrate lens to increase the directivity and the effective isotropic radiated power (EIRP). The array delivers a total power output of 68 mW with an effective isotropic radiated power of 4.4 W. The DC to RF efficiency of the array is 12%. The substrate lens approach provides a planar design that eliminates substrate mode problems and, therefore, is easily scaled to millimeter-wave frequencies. RP KORMANYOS, BK (reprint author), UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109, 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 1051-8207 J9 IEEE MICROW GUIDED W JI IEEE Microw. Guided Wave Lett. PD JUL PY 1994 VL 4 IS 7 BP 226 EP 228 DI 10.1109/75.298248 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA NZ488 UT WOS:A1994NZ48800004 ER PT J AU FILIPOVIC, DF BRADLEY, RF REBEIZ, GM AF FILIPOVIC, DF BRADLEY, RF REBEIZ, GM TI A PLANAR BROAD-BAND BALANCED DOUBLER USING A NOVEL BALUN DESIGN SO IEEE MICROWAVE AND GUIDED WAVE LETTERS LA English DT Article AB We report on the design and measurement of a broadband MIC balanced varactor frequency doubler. The design incorporates a novel balun to achieve a grounded CPW-to-slotline transition. The balanced structure offers inherent isolation in the output port from all odd harmonics including the fundamental frequency. Measurements show a port-to-port conversion loss between 8 and 10 dB over an output frequency range of 6-10 GHz. The design can be easily scaled to millimeter-wave frequencies using a monolithic approach. RP FILIPOVIC, DF (reprint author), UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109, USA. NR 0 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 1051-8207 J9 IEEE MICROW GUIDED W JI IEEE Microw. Guided Wave Lett. PD JUL PY 1994 VL 4 IS 7 BP 229 EP 231 DI 10.1109/75.298249 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA NZ488 UT WOS:A1994NZ48800005 ER PT J AU MCGARRY, F AF MCGARRY, F TI PROCESS IMPROVEMENT IS A BOTTOM-UP TASK SO IEEE SOFTWARE LA English DT Article RP MCGARRY, F (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 2 TC 1 Z9 1 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0740-7459 J9 IEEE SOFTWARE JI IEEE Softw. PD JUL PY 1994 VL 11 IS 4 BP 13 EP 13 PG 1 WC Computer Science, Software Engineering SC Computer Science GA NU016 UT WOS:A1994NU01600009 ER PT J AU BASILI, V GREEN, S AF BASILI, V GREEN, S TI SOFTWARE PROCESS EVOLUTION AT THE SEL SO IEEE SOFTWARE LA English DT Article C1 NASA,GODDARD SPACE FLIGHT CTR,DIV FLIGHT DYNAM,GREENBELT,MD 20771. RP BASILI, V (reprint author), UNIV MARYLAND,INST ADV COMP STUDIES,DEPT CS,COLL PK,MD 20742, USA. NR 7 TC 37 Z9 38 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 0740-7459 J9 IEEE SOFTWARE JI IEEE Softw. PD JUL PY 1994 VL 11 IS 4 BP 58 EP 66 DI 10.1109/52.300090 PG 9 WC Computer Science, Software Engineering SC Computer Science GA NU016 UT WOS:A1994NU01600014 ER PT J AU TAM, KS YANG, LF DRAVID, N AF TAM, KS YANG, LF DRAVID, N TI MODELING THE PROTECTION SYSTEM COMPONENTS OF THE SPACE STATION ELECTRIC-POWER SYSTEM SO IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS LA English DT Article AB To facilitate protection system studies on the space station electric power system, there is a need to develop a model that can accurately and conveniently simulate both the power system and the protection system. Models for two major protective devices, the remote bus isolater and the remote power controller, are described. These models have been installed in a power system model resembling one channel of the space station power system. The usefulness of these models in protection system studies is demonstrated. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP TAM, KS (reprint author), VIRGINIA POLYTECH INST & STATE UNIV,DEPT ELECT ENGN,BLACKSBURG,VA 24061, USA. NR 15 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 0018-9251 J9 IEEE T AERO ELEC SYS JI IEEE Trans. Aerosp. Electron. Syst. PD JUL PY 1994 VL 30 IS 3 BP 800 EP 808 DI 10.1109/7.303749 PG 9 WC Engineering, Aerospace; Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA NV887 UT WOS:A1994NV88700014 ER PT J AU MARCHYWKA, M MOSES, D AF MARCHYWKA, M MOSES, D TI OPTICAL CHARACTERIZATION OF DIAMOND MIS CAPACITORS SO IEEE TRANSACTIONS ON ELECTRON DEVICES LA English DT Article DE DIAMOND ELECTRONICS; MIS CAPACITOR; UV; VACUUM ULTRAVIOLET; PHOTODETECTORS ID ULTRAVIOLET; STABILITY; DETECTORS; DIODE AB The transient photoresponse properties of diamond metal-insulator-semiconductor (MIS) capacitors have been characterized for the first time. Capacitors were fabricated on natural diamond using an electrochemical cleaning step with a CVD SiO2 dielectric and an optional carbon implantation to create a nonuniform doping profile. Devices were found to function as integrating photodetectors and were evaluated bv the spectral dependence of the transient photocapacitance (PC). We discuss a model that distinguishes between the responses due to inversion layer population and that due to bulk trap occupancy changes. Inversion charge generation was observed at all wavelengths investigated and it dominated the PC transient at photon energies above 3 eV. Possible reasons for this result are discussed and analyzed. We could not demonstrate a suitable way to use carbon implantation to form a surface n-type layer in a MIS device without degrading the device IV properties and eliminating the integrating photoresponse observed on non-implanted devices. These results suggest that diamond charge-storage devices can function only if the diamond surface is prepared properly before device fabrication. C1 NASA,ESA,SOLAR & HELIOSPHER OBSERV PROGRAM,WASHINGTON,DC 20546. RP MARCHYWKA, M (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,SOLAR PHYS BRANCH,WASHINGTON,DC 20375, USA. NR 31 TC 6 Z9 6 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 0018-9383 J9 IEEE T ELECTRON DEV JI IEEE Trans. Electron Devices PD JUL PY 1994 VL 41 IS 7 BP 1265 EP 1272 DI 10.1109/16.293357 PG 8 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA NV886 UT WOS:A1994NV88600025 ER PT J AU ZRNIC, DS BALAKRISHNAN, N RYZHKOV, AV DURDEN, SL AF ZRNIC, DS BALAKRISHNAN, N RYZHKOV, AV DURDEN, SL TI USE OF COPOLAR CORRELATION-COEFFICIENT FOR PROBING PRECIPITATION AT NEARLY VERTICAL INCIDENCE SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID RADAR AB We present observations of the copolar correlation coefficient between horizontally and vertically polarized echoes \rho(hv)(0)\. These were made with ground-based and airborne weather radars at nearly vertical incidence. A sharp decrease of \rho(hv)(0)\ occurs at the bright band bottom, and is attributed to a varying mixture of hydrometeors with diverse shape, size, and thermodynamic phase. The largest contribution to decorrelation seems to come from wet aggregates; this is substantiated by consideration of two simple models. One consists of randomly oriented wet prolate spheroids, and the other considers an ensemble of distorted spheres. Prolates with axis ratios of 3 or distorted spheres with rms roughness equal to 15% of the diameter decrease the correlation to 0.8 at S band. At Ku band and for the size range encountered in the bright band, the decrease is a function of equivalent diameter because scattering is in the Mie regime. \rho(hv)(0)\ measurement at 13.8 GHz and from the aircraft are the first ever. Also, differential phase and differential reflectivity at a 10-degrees off nadir are the first of its kind. These last two variables showed a distinct signature in the bright band. This is significant because it might lead to applications on airborne or spaceborne platforms. C1 INDIAN INST SCI,BANGALORE 560012,KARNATAKA,INDIA. JET PROP LAB,PASADENA,CA 91109. RP ZRNIC, DS (reprint author), NOAA,ENTOMOL RES LABS,NATL SEVERE STORMS LAB,DOPPLER RADAR & REMOTE SENSING RES GRP,NORMAN,OK 73069, USA. NR 11 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1994 VL 32 IS 4 BP 740 EP 748 DI 10.1109/36.298003 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 PB219 UT WOS:A1994PB21900002 ER PT J AU CARANDE, RE AF CARANDE, RE TI ESTIMATING OCEAN COHERENCE TIME USING DUAL-BASE-LINE INTERFEROMETRIC SYNTHETIC-APERTURE RADAR SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID INTERNAL WAVES; SPECTRA; FOCUS; SEA AB A new technique for measuring the coherence time of the ocean surface at radar wavelengths has been developed and tested. This technique requires an interferometric synthetic aperture radar system with at least two unique baselines along the direction of platform motion. The coherence time of the surface may be presented as a high-resolution coherence time map. This technique was tested using the JPL AIRSAR along-track interferometer. Measurements of the ocean coherence at the L-band were made at high spatial resolution under a variety of conditions. A new operating technique that results in the required two baselines is described. Some parametric analysis is performed pertaining to the design of such a system. A representative interferometric data set acquired at the Strait of Messina in 1991 is presented to illustrate the technique. The interferometric phase data reveal and measure tidal currents flowing through the strait, while the coherence time image shows considerable structure not visible in the backscatter or phase image. Coherence times in and around the strait were measured to be of the order of 0.1 s at the L-band, which is in agreement with previous estimates and measurements. RP CARANDE, RE (reprint author), JET PROP LAB,RADAR SCI & ENGN SECT,PASADENA,CA 91109, USA. NR 24 TC 47 Z9 49 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1994 VL 32 IS 4 BP 846 EP 854 DI 10.1109/36.298012 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 PB219 UT WOS:A1994PB21900011 ER PT J AU GREGG, WW PATT, FS AF GREGG, WW PATT, FS TI ASSESSMENT OF TILT CAPABILITY FOR SPACEBORNE GLOBAL OCEAN COLOR SENSORS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID OPTICAL-PROPERTIES; NATURAL-WATERS; MODEL; ATMOSPHERES; IRRADIANCE; SCATTERING; RADIANCE; AEROSOL; SCANNER AB The importance of tilt capability for sun glint avoidance for future global ocean color missions was analyzed. The analyses focused on Sea-viewing Wide Field-of-view Sensor (SeaWiFS) mission, because its radiometric, orbital, and sensor characteristics are well defined. The analyses concentrated on two major questions: 1) does tilting to avoid sun glint increase or decrease the total ocean coverage, and 2) at high latitudes far from the region of maximum sun glint, should the sensor be tilted or untilted? For ocean coverage maximization, if the sensitivity of ocean color algorithms to sun glint is of the same order as the error in the atmospheric correction algorithms, then a tilted sensor produces nearly 20 percent better coverage than an untilted one after 2 d in the absence of clouds, and 12 percent after 4 d including clouds. Thus, the tilt capability can improve the ocean coverage of future ocean color missions. At high latitudes differences in transmitted water-leaving radiance between tilted and untilted sensors were well within the algorithm errors. Furthermore, sun glint radiances exceeding the algorithm errors occurred at high wind speeds as far as 70-algorithms from the solar declination, suggesting that sensors should remain in the tilted mode up to this limit. C1 GEN SCI CORP,SEAWIFS PROJECT,LAUREL,MD 20707. RP GREGG, WW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CTR GLOBAL CHANGE DATA,SEAWIFS PROJECT,GREENBELT,MD 20771, USA. NR 24 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 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD JUL PY 1994 VL 32 IS 4 BP 866 EP 877 DI 10.1109/36.298014 PG 12 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA PB219 UT WOS:A1994PB21900013 ER PT J AU SIDIROPOULOS, ND BARAS, JS BERENSTEIN, CA AF SIDIROPOULOS, ND BARAS, JS BERENSTEIN, CA TI OPTIMAL FILTERING OF DIGITAL BINARY IMAGES CORRUPTED BY UNION/INTERSECTION NOISE SO IEEE TRANSACTIONS ON IMAGE PROCESSING LA English DT Article ID MORPHOLOGICAL FILTERS AB We model digital binary image data as realizations of a uniformly bounded discrete random set (or discrete random set, for short), which is a mathematical object that can be directly defined on a finite lattice. We consider the problem of estimating realizations of discrete random sets distorted by a degradation process that can be described by a union/intersection noise model. Two distinct optimal filtering approaches are pursued. The first involves a class of ''mask'' filters, which arises quite naturally from the set-theoretic analysis of optimal filters. The second approach involves a class of morphological filters. We prove that under i.i.d noise morphological openings, closings, unions of openings, and intersections of closings can be viewed as MAP estimators of morphologically smooth signals. Then, we show that by using an appropriate (under a given degradtion model) expansion of the optimal filter, we can obtain universal characterizations of optimality that do not rely on strong assumptions regarding the spatial interaction of geometrical primitives of the signal and the noise. The results generalize to gray-level images in a fairly straightforward manner. C1 NASA,CTR SATELLITE & HYBRID COMMUN NETWORKS,WASHINGTON,DC. RP SIDIROPOULOS, ND (reprint author), UNIV MARYLAND,SYST RES INST,COLLEGE PK,MD 20742, USA. NR 41 TC 13 Z9 13 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 1057-7149 J9 IEEE T IMAGE PROCESS JI IEEE Trans. Image Process. PD JUL PY 1994 VL 3 IS 4 BP 382 EP 403 DI 10.1109/83.298394 PG 22 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA PU068 UT WOS:A1994PU06800004 PM 18291938 ER PT J AU BALDI, P ATIYA, AF AF BALDI, P ATIYA, AF TI HOW DELAYS AFFECT NEURAL DYNAMICS AND LEARNING SO IEEE TRANSACTIONS ON NEURAL NETWORKS LA English DT Article ID DIFFERENTIAL EQUATIONS; NETWORKS; OSCILLATORS AB We investigate the effects of delays on the dynamics and, in particular, on the oscillatory properties of simple neural network models. We extend previously known results regarding. the effects of delays on stability and convergence properties. We treat in detail the case of ring networks for which we derive simple conditions for oscillating behavior and several formulas to predict the regions of bifurcation, the periods of the limit cycles and the phases of the different neurons. These results in turn can readily be applied to more complex and more biologically motivated architectures, such as layered networks. In general, the main result is that delays tend to increase the period of oscillations and broaden the spectrum of possible frequencies, in a quantifiable way. Simulations show that the theoretically predicted values are in excellent agreement with the numerically observed behavior. Adaptable delays are then proposed as one additional mechanism through which neural systems could tailor their own dynamics. Accordingly, we derive recurrent back-propagation learning formulas for the adjustment of delays and other parameters in networks with delayed interactions and discuss some possible applications. C1 QANTXX INC,HOUSTON,TX 77027. JET PROP LAB,PASADENA,CA 91109. RP BALDI, P (reprint author), CALTECH,DIV BIOL,PASADENA,CA 91109, USA. NR 30 TC 269 Z9 284 U1 0 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1045-9227 J9 IEEE T NEURAL NETWOR JI IEEE Trans. Neural Netw. PD JUL PY 1994 VL 5 IS 4 BP 612 EP 621 DI 10.1109/72.298231 PG 10 WC Computer Science, Artificial Intelligence; Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA PA316 UT WOS:A1994PA31600008 PM 18267834 ER PT J AU CAMPBELL, LL PURVIANCE, JE AF CAMPBELL, LL PURVIANCE, JE TI INTERPOLATION MODELING OF S-PARAMETER DATA-BASES FOR USE IN MONTE-CARLO SIMULATIONS SO INTERNATIONAL JOURNAL OF MICROWAVE AND MILLIMETER-WAVE COMPUTER-AIDED ENGINEERING LA English DT Article AB A statistical interpolation technique is presented for modeling S-parameter measurements for use in statistical analysis and design of circuits. This is accomplished by interpolating among the measurements in an S-parameter data base in a statistically valid manner. (C) 1994 John Wiley & Sons. Inc. C1 UNIV IDAHO,NASA,SPACE ENGN RES CTR VLSI SYST DESIGN,MOSCOW,ID 83843. RP CAMPBELL, LL (reprint author), NIPPONDENSO LA LABS,CARLSBAD,CA 92009, USA. NR 16 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 1050-1827 J9 INT J MICROWAVE MILL JI Int. J. Microw. Millimeter-Wave Comput.-Aided Eng. PD JUL PY 1994 VL 4 IS 3 BP 282 EP 296 DI 10.1002/mmce.4570040308 PG 15 WC Computer Science, Interdisciplinary Applications; Engineering, Electrical & Electronic SC Computer Science; Engineering GA NT194 UT WOS:A1994NT19400007 ER PT J AU AHUMADA, A AF AHUMADA, A TI AGE-RELATED CATARACT AND CONTRAST SENSITIVITY SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Letter RP AHUMADA, A (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQ, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD JUL PY 1994 VL 35 IS 8 BP 3128 EP 3128 PG 1 WC Ophthalmology SC Ophthalmology GA NY460 UT WOS:A1994NY46000002 PM 8045706 ER PT J AU BAUCOM, RM MARCHELLO, JM AF BAUCOM, RM MARCHELLO, JM TI POWDER CURTAIN PREPREG PROCESS SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB Powder prepregging processes being developed for advanced composite materials overcome many of the difficulties associated with melt, solution and slurry prepregging. In addition, studies have demonstrated that powder coating is applicable to thermoplastics and thermosets and that processing costs are comparable to conventional hot melt prepregging. The powder curtain prepreg process offers advantages in quality control and powder handling over other methods which utilize fluidized beds or slurries. The dry powder curtain feed method provides for the uniform metering and efficient application of polymer powder materials onto fiber webs for the manufacture of high quality composite towpreg. The process has been demonstrated for a wide variety of thermosets and thermoplastic resins. Towpreg, prepared. by the powder curtain method, has been made into unidirectional and woven composite test specimens that have exhibited excellent mechanical properties. C1 OLD DOMINION UNIV,NORFOLK,VA 23508. RP BAUCOM, RM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 15 TC 5 Z9 5 U1 0 U2 2 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD JUL PY 1994 VL 25 IS 4 BP 31 EP 35 PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA NV447 UT WOS:A1994NV44700004 ER PT J AU SPANOS, PD MUSHUNG, LJ NELSON, DA HAMILTON, DA AF SPANOS, PD MUSHUNG, LJ NELSON, DA HAMILTON, DA TI SPECTRAL REPRESENTATION OF HIGH-FREQUENCY SPACE-SHUTTLE DATA SO JOURNAL OF AEROSPACE ENGINEERING LA English DT Article ID MULTIVARIATE RANDOM-PROCESSES; RECURSIVE SIMULATION AB High frequency Space Shuttle liftoff data are treated by autoregressive (AR) and autoregressive-moving-average (ARMA) digital algorithms. These algorithms provide useful information on the spectral densities of the data. Further, they yield spectral models, which lend themselves to incorporation into the concept of the random response spectrum. This concept yields a reasonably smooth power spectrum for the design of structural and mechanical systems when the available data bank is limited. Due to the nonstationarity of the liftoff event, the pertinent data are split into three slices. Each of the slices is associated with a rather distinguishable phase of the liftoff event, in which stationarity can be expected. The presented results are preliminary in nature; they aim to call attention to the availability of the discussed concepts and to the need to augment the Space Shuttle data bank as more flights are completed. C1 LOCKHEED ES CO,HOUSTON,TX 77258. NASA,LYNDON B JOHNSON SPACE CTR,DYNAM & LOAD SECT,HOUSTON,TX 77058. RP SPANOS, PD (reprint author), RICE UNIV,BROWN SCH ENGN,POB 1892,HOUSTON,TX 77251, USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU ASCE-AMER SOC CIVIL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0893-1321 J9 J AEROSPACE ENG JI J. Aerosp. Eng. PD JUL PY 1994 VL 7 IS 3 BP 315 EP 327 DI 10.1061/(ASCE)0893-1321(1994)7:3(315) PG 13 WC Engineering, Aerospace; Engineering, Civil SC Engineering GA QU052 UT WOS:A1994QU05200005 ER PT J AU CONNER, DA WELLMAN, JB AF CONNER, DA WELLMAN, JB TI HOVER ACOUSTIC CHARACTERISTICS OF THE XV-15 WITH ADVANCED TECHNOLOGY BLADES SO JOURNAL OF AIRCRAFT LA English DT Article AB An experiment has been performed to investigate the far-field hover acoustic characteristics of the XV-15 aircraft with advanced technology blades (ATB). An extensive, high-quality, far-field acoustics data base was obtained for a rotor tip speed range of 645-771 ft/s. A 12-microphone, 500-ft radius semicircular array combined with two aircraft headings provided acoustic data over the full 360-deg azimuth about the aircraft with a resolution of 15 deg. Altitude variations provided data from near in-plane to 45 deg below the rotor tip path plane. Acoustic directivity characteristics in the lower hemisphere are explored through pressure time histories, narrow-band spectra, and contour plots. Directivity patterns were found to vary greatly with azimuth angle, especially in the forward quadrants. Sharp positive pressure pulses typical of blade-vortex interactions were found to propagate aft of the aircraft and were most intense at 45 deg below the rotor plane. Modest overall sound pressure levels were measured near in-plane indicating that thickness noise is not a major problem for this aircraft when operating in the hover mode with ATB. Rotor tip speed reductions reduced the average overall sound pressure level [dB (0.0002 dyne/cm2)] by nearly 8 dB in-plane, and by almost 5 dB at 12.6 deg below the rotor plane. RP CONNER, DA (reprint author), NASA,LANGLEY RES CTR,DIV ACOUST,APPL ACOUST BRANCH,ATCOM,ARDEC,HAMPTON,VA 23665, USA. NR 0 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1994 VL 31 IS 4 BP 737 EP 744 DI 10.2514/3.46555 PG 8 WC Engineering, Aerospace SC Engineering GA PA474 UT WOS:A1994PA47400001 ER PT J AU WINGROVE, RC BACH, RE AF WINGROVE, RC BACH, RE TI SEVERE TURBULENCE AND MANEUVERING FROM AIRLINE FLIGHT RECORDS SO JOURNAL OF AIRCRAFT LA English DT Article AB Digital flight records from reported clear-air turbulence incidents are used to determine winds and turbulence, to determine maneuver g loads, and to analyze control problems. Many cases of severe turbulence are found downwind of mountains and thunderstorms where sharp, sudden jolts are associated with vortices in atmospheric waves. Other cases of severe turbulence are found in strong updrafts above thunderstorm buildups that may be undetected by onboard weather radar. An important finding is that there are large maneuvering loads in over half of the reported clear-air turbulence incidents. Maneuvering loads are determined through an analysis of the short-term variations in elevator deflection and aircraft pitch angle. For altitude control in mountain waves the results indicate that small pitch angle changes with proper timing are sufficient to counter variations in vertical wind. For airspeed control in strong mountain waves, however, there is neither the available thrust nor the quickness in engine response necessary to counter the large variations in winds. RP WINGROVE, RC (reprint author), NASA,AMES RES CTR,DIV FLIGHT SYST & SIMULAT RES,AIRCRAFT GUIDANCE & NAVIGAT BRANCH,MOFFETT FIELD,CA 94035, USA. NR 0 TC 8 Z9 8 U1 0 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 JUL-AUG PY 1994 VL 31 IS 4 BP 753 EP 760 DI 10.2514/3.46557 PG 8 WC Engineering, Aerospace SC Engineering GA PA474 UT WOS:A1994PA47400003 ER PT J AU ROSS, HM PERKINS, JN AF ROSS, HM PERKINS, JN TI TAILORING STALL CHARACTERISTICS USING LEADING-EDGE DROOP MODIFICATIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB Wind-tunnel tests were performed on a 1/6-scale model of a general aviation trainer configuration in the NASA Langley 12-Foot Low-Speed Tunnel. The purpose of these tests was to investigate the configuration's high-angle-of-attack characteristics as well as the low-speed stability and control characteristics. The focus of the high-angle-of-attack testing was to develop leading-edge modifications that would tailor the stall characteristics of the model. The testing resulted in two different leading-edge modifications. A small profile leading-edge droop on the outboard 29% of the wing was developed that kept the outboard wing flow attached to high angles of attack, resulting in increased roll damping and added aileron authority. The second leading-edge modification developed was a large profile leading-edge droop on the outboard 50% of the wing. This large droop kept the outboard wing flow attached to very high angles of attack that greatly improved the roll damping characteristics and stall/departure resistance as well as provided large increases in aileron authority. RP ROSS, HM (reprint author), NASA,LANGLEY RES CTR,DIV FLIGHT DYNAM & CONTROL,FLIGHT DYNAM BRANCH,MS 355,HAMPTON,VA 23665, USA. NR 0 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1994 VL 31 IS 4 BP 767 EP 772 DI 10.2514/3.46559 PG 6 WC Engineering, Aerospace SC Engineering GA PA474 UT WOS:A1994PA47400005 ER PT J AU BOYDEN, RP DRESS, DA FOX, CH HUFFMAN, JK CRUZ, CI AF BOYDEN, RP DRESS, DA FOX, CH HUFFMAN, JK CRUZ, CI TI SUBSONIC STATIC AND DYNAMIC STABILITY CHARACTERISTICS OF A NASP CONFIGURATION SO JOURNAL OF AIRCRAFT LA English DT Article; Proceedings Paper CT AIAA 31st Aerospace Sciences Meeting CY JAN 11-14, 1993 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB Wind-tunnel tests of a National Aero-Space Plane configuration were conducted in the NASA Langley Research Center (LaRC) 7- by 10-Foot High Speed Tunnel. The model used is a LaRC designed blended body configuration. Static and dynamic stability characteristics were measured at Mach numbers of 0.3, 0.6, and 0.8. In addition to tests of the baseline configuration, component buildup tests with a canard surface and a body flap were conducted. The baseline configuration showed positive static stability except at the higher angles of attack at 0.8 Mach number. The baseline configuration has positive damping about all three axes. There was generally good agreement between the in-phase dynamic parameters and the corresponding static data. Also included are comparisons of the experimental damping parameters with results from the engineering predictive code Aerodynamic Preliminary Analysis System (APAS). The APAS damping predictions are good for the roll mode, and only fair for the pitch and yaw modes. RP BOYDEN, RP (reprint author), NASA,LANGLEY RES CTR,DIV APPL AERODYNAM,HIGH REYNOLDS NUMBER AERODYNAM BRANCH,MS 267,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1994 VL 31 IS 4 BP 879 EP 885 DI 10.2514/3.46574 PG 7 WC Engineering, Aerospace SC Engineering GA PA474 UT WOS:A1994PA47400020 ER PT J AU CARR, LW CHANDRASEKHARA, MS BROCK, NJ AF CARR, LW CHANDRASEKHARA, MS BROCK, NJ TI QUANTITATIVE STUDY OF UNSTEADY COMPRESSIBLE FLOW ON AN OSCILLATING AIRFOIL SO JOURNAL OF AIRCRAFT LA English DT Article AB Real-time interferometric measurements of the flow near the leading edge of an oscillating airfoil offer detailed experimental quantification of the locally compressible flowfield that surrounds an oscillating airfoil at moderate subsonic Mach numbers. Interferograms obtained by a specially adapted real-time point-diffraction interferometry technique have revealed some important characteristics or this complex, and very rapidly varying, locally supersonic flow. Instantaneous pressure distributions deter-mined from these interferograms document the effect of unsteadiness on the leading-edge flow environment. RP CARR, LW (reprint author), NASA,AMES RES CTR,USA ATCOM,AEROFLIGHTDYNAM DIRECTORATE,MS 260-1,MOFFETT FIELD,CA 94035, USA. NR 0 TC 11 Z9 12 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD JUL-AUG PY 1994 VL 31 IS 4 BP 892 EP 898 DI 10.2514/3.46576 PG 7 WC Engineering, Aerospace SC Engineering GA PA474 UT WOS:A1994PA47400022 ER PT J AU CHANDRA, S MCPETERS, RD PLANET, W NAGATANI, RM AF CHANDRA, S MCPETERS, RD PLANET, W NAGATANI, RM TI THE 27 DAY SOLAR UV RESPONSE OF STRATOSPHERIC OZONE - SOLAR-CYCLE 21 VS SOLAR-CYCLE 22 SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article; Proceedings Paper CT International Symposium on Middle Atmosphere Science CY MAR, 1992 CL KYOTO UNIV, RADIO ATMOSPHERE SCI CTR, KYOTO, JAPAN SP MINIST EDUC SCI & CULTURE JAPAN, SCOSTEP, UNION RADIO SCI INT, INT ASSOC METEOROL & ATMOSPHER PHYS, INT ASSOC GEOMAGNETISM & AERON, SOC GEOMAGNETISM & EARTH PLANETARY & SPACE SCI, METEOREOL SOC JAPAN HO KYOTO UNIV, RADIO ATMOSPHERE SCI CTR ID ULTRAVIOLET VARIATIONS; MIDDLE ATMOSPHERE; BACKSCATTER ULTRAVIOLET; FLUX AB A correlative study of ozone and the solar UV flux on the time scale of a solar rotation shows an anomalous response of ozone in the upper stratosphere during solar cycle 22. The study. which is based on the analysis of ozone and solar UV flux measured by the SBUV/2 spectrometer on NOAA 11 (January 1989 December 1990), shows a sharp transition from an in-phase relation between ozone and the solar UV flux below 2 mb to an almost out-of-phase relation above 1 mb. Such a phase change is not predicted by photochemical models and was not observed during solar cycle 21. The ozone measurements from the Nimbus-7 SBUV spectrometer from 1979 to 1984 showed an almost in-phase relation between ozone and the solar UV flux at these heights (in agreement with model predictions). Similar studies of ozone and temperature relations between 30 and 1 mb did not show significant changes from the solar cycle 21 to 22. The temperature oscillations appear to be primarily of dynamical origin, with no apparent correlation with solar UV flux. C1 NOAA,WASHINGTON,DC 20233. RP CHANDRA, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 916,GREENBELT,MD 20771, USA. RI McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 23 TC 13 Z9 14 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 JUL PY 1994 VL 56 IS 9 BP 1057 EP 1065 DI 10.1016/0021-9169(94)90043-4 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NQ280 UT WOS:A1994NQ28000006 ER PT J AU GREEN, S SCHWENKE, DW HUO, WM AF GREEN, S SCHWENKE, DW HUO, WM TI RAMAN Q-BRANCH LINE-SHAPES AS A TEST OF A H-2-AR INTERMOLECULAR POTENTIAL SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID VANDERWAALS MOLECULES; ENERGY SURFACE; AR; D2; HE; FORCES AB The Le Roy-Hutson intermolecular potential for H-2-Ar, which was derived from analysis of spectral data for the van der Waals complex and also shown to predict gas kinetic transport cross sections in good accord with experimental values, was subsequently found to provide rather poor predictions (small by nearly a factor of 2) for vibrational Q-branch Raman line shift cross sections. More recently, an ab initio intermolecular potential for this system has been calculated and scaled to agree with the earlier one in the region of the minimum where the latter is expected to be accurate [D. W. Schwenke et al., J. Chem. Phys. 98, 4738 (1993)]. We show here that this potential predicts line shifts in much better accord with experiment (about 10% large), but its predictions for linewidths are significantly less satisfactory. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP GREEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025, USA. RI schwenke, david/I-3564-2013 NR 22 TC 3 Z9 3 U1 2 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 JUL 1 PY 1994 VL 101 IS 1 BP 15 EP 19 DI 10.1063/1.468188 PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NT521 UT WOS:A1994NT52100002 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR AF BAUSCHLICHER, CW LANGHOFF, SR TI THEORETICAL-STUDY OF THE ELECTRONIC STATES OF ALB SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CORRELATED MOLECULAR CALCULATIONS; GAUSSIAN-BASIS SETS; ANO BASIS-SETS; IONIZATION-POTENTIALS; WAVE-FUNCTIONS; GROUND-STATE; ROW ATOMS; DIMER; AL2; SPECTROSCOPY AB The singlet, triplet, and quintet states of AlB below about 30 000 cm(-1) are studied theoretically to facilitate spectroscopic investigations and for comparison with analogous calculations on the Al-2 and B-2 molecules. The ground state of AlB is X (3) Sigma(-) with a dissociation energy of 1.96+/-0.06 eV. The A (3) Pi state is computed to lie only 610 cm(-1) above the ground state. Since transitions from the (2)(3) Sigma(-) state to both the X (3) Sigma(-) and A (3) Pi states are predicted to be relatively strong, these transitions in the region of 17 000- 18 000 cm(-1) should be an excellent means of characterizing AlB and of determining the X-A separation. The adiabatic ionization potential to form the X (2) Sigma(+) ground state of AlB+ is estimated to be 7.05 eV. Overall the spectroscopy of AlB is much more similar to Al-2 than B-2. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 27 TC 6 Z9 6 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUL 1 PY 1994 VL 101 IS 1 BP 80 EP 85 DI 10.1063/1.468137 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NT521 UT WOS:A1994NT52100009 ER PT J AU RENDELL, AP LEE, TJ AF RENDELL, AP LEE, TJ TI COUPLED-CLUSTER THEORY EMPLOYING APPROXIMATE INTEGRALS - AN APPROACH TO AVOID THE INPUT/OUTPUT AND STORAGE BOTTLENECKS SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID QUADRATIC CONFIGURATION-INTERACTION; GAUSSIAN-BASIS SETS; VIBRATIONAL FREQUENCIES; ELECTRON CORRELATION; TRIPLE EXCITATIONS; QUANTUM-CHEMISTRY; TRANSITION-STATE; FORCE-FIELDS; MP2 ENERGY; ABINITIO AB By representing orbital products in an expansion basis, certain classes of two-electron integrals are approximated for use in CCSD(T) calculations (singles and doubles coupled-cluster plus a perturbational estimate of the effects of connected triple excitations). This leads to a very large reduction in disk storage and input/output requirements, with usually only a modest increase in computational effort. The new procedure will allow very large CCSD(T) calculations to be undertaken, limited only by available processor time, Using the molecular basis as the expansion basis, explicit numerical comparisons of equilibrium geometries, harmonic frequencies, and energy differences indicate that the error due to the use of approximate integrals is less than the error associated with truncation of the molecular basis set. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP RENDELL, AP (reprint author), SERC,DARESBURY LAB,WARRINGTON WA4 4AD,CHESHIRE,ENGLAND. RI Rendell, Alistair/A-4883-2008; Lee, Timothy/K-2838-2012 OI Rendell, Alistair/0000-0002-9445-0146; NR 52 TC 120 Z9 120 U1 1 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUL 1 PY 1994 VL 101 IS 1 BP 400 EP 408 DI 10.1063/1.468148 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NT521 UT WOS:A1994NT52100043 ER PT J AU FU, R DELGENIO, AD ROSSOW, WB AF FU, R DELGENIO, AD ROSSOW, WB TI INFLUENCE OF OCEAN SURFACE CONDITIONS ON ATMOSPHERIC VERTICAL THERMODYNAMIC STRUCTURE AND DEEP CONVECTION SO JOURNAL OF CLIMATE LA English DT Article ID TROPICAL PACIFIC; ANNUAL CYCLE; INTERANNUAL VARIABILITY; EQUATORIAL PACIFIC; HADLEY CIRCULATION; BOUNDARY-LAYER; TEMPERATURE; CONVERGENCE; WIND; REGIONS AB The authors analyze the influence of sea surface temperature (SST) and surface wind divergence on atmospheric thermodynamic structure and the resulting effects on the occurrence of deep convection using National Meteorological Center radiosonde data and International Satellite Cloud Climatology Program data for July 1983-July 1985. The onset of deep convection requires not only the existence of positive convective available potential energy (CAPE), but also an unstable planetary boundary layer (PBL). A stable PBL is observed to suppress deep convection even when CAPE is positive. Variations of SST have a major effect on CAPE, but surface wind divergence can also affect deep convection by changing the lapse rate in the lower troposphere and humidity in the PBL. Specifically, when SST greater-than-or-equal-to 28-degrees-C, CAPE is always positive, and surface wind divergence does not qualitatively change the buoyancy profile above the PBL. Strong surface wind divergence, however, stabilizes the PBL so as to suppress the initiation of deep convection. In warm SST regions, CAPE > 0 regardless of assumptions about condensate loading, although the pseudoadiabatic limit is more consistent with the observed deep convection than the reversible moist-adiabatic limit under these circumstances. When SST < 27-degrees-C, CAPE is usually negative and inhibits convection, but strong surface wind convergence can destabilize the inversion layer and moisten the PBL enough to make the atmosphere neutrally stable in the mean. As a result, deep convection is generally enhanced either when SST greater-than-or-equal-to 28-degrees-C in the absence of strong surface wind divergence or when strong surface wind convergence occurs even if SST < 27-degrees-C. The anomalous suppression of deep convection in the warm area of the equatorial west Pacific lying between the ITCZ and SPCZ is probably caused by dryness in the PBL and an inversion in that area. The seasonal cycles of deep convection and surface wind divergence are in phase with the maximum solar radiation and lead SST for one to three months in the central Pacific. The change of PBL relative humidity plays a critical role in the changeover to convective instability in this case. The seasonal change of deep convection and associated clouds seems not to have important effects on the seasonal change of local SST in the central Pacific. C1 JET PROP LAB,PASADENA,CA 91109. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,GREENBELT,MD 20771. RI Del Genio, Anthony/D-4663-2012; Fu, Rong/B-4922-2011; Rossow, William/F-3138-2015 OI Del Genio, Anthony/0000-0001-7450-1359; NR 37 TC 62 Z9 64 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD JUL PY 1994 VL 7 IS 7 BP 1092 EP 1108 DI 10.1175/1520-0442(1994)007<1092:IOOSCO>2.0.CO;2 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NX183 UT WOS:A1994NX18300004 ER PT J AU CHOI, H MOIN, P AF CHOI, H MOIN, P TI EFFECTS OF THE COMPUTATIONAL TIME-STEP ON NUMERICAL-SOLUTIONS OF TURBULENT-FLOW SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID CHANNEL FLOW AB Effects of large computational time steps on the computed turbulence were investigated using a fully implicit method. In turbulent channel flow computations the largest computational time step in wall units which led to accurate prediction of turbulence statistics was determined. Turbulence fluctuations could not be sustained if the computational time step was near or larger than the Kolmogorov time scale. (C) 1994 Academic Press, Inc. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SEOUL NATL UNIV,DEPT MECH ENGN,SEOUL 151742,SOUTH KOREA. RP CHOI, H (reprint author), STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305, USA. RI Choi, Haecheon/D-1016-2011 OI Choi, Haecheon/0000-0003-0696-847X NR 8 TC 255 Z9 259 U1 1 U2 22 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 JUL PY 1994 VL 113 IS 1 BP 1 EP 4 DI 10.1006/jcph.1994.1112 PG 4 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA NR928 UT WOS:A1994NR92800001 ER PT J AU CARPENTER, WC BARTHELEMY, JF AF CARPENTER, WC BARTHELEMY, JF TI COMMON MISCONCEPTIONS ABOUT NEURAL NETWORKS AS APPROXIMATORS SO JOURNAL OF COMPUTING IN CIVIL ENGINEERING LA English DT Article ID MULTILAYER FEEDFORWARD NETWORKS; DERIVATIVES AB A current trend in scientific and engineering computing is to use neural-network approximations instead of polynomial approximations or other types of approximations involving mathematical functions. A number of misconceptions have arisen concerning neural networks as approximators. This paper eliminates these misconceptions. In so doing, the paper examines the computational efficiency of neural-network approximations compared to polynomial approximations, examines the effect of using underdetermined neural-network approximations, examines the effect of design point selection on the quality of neural-network approximations, and examines the computing time required to train neural networks compared to the time to develop polynomial approximations. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP CARPENTER, WC (reprint author), UNIV S FLORIDA,DEPT CIVIL ENGN & MECH,TAMPA,FL 33620, USA. NR 22 TC 38 Z9 38 U1 0 U2 2 PU ASCE-AMER SOC CIVIL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0887-3801 J9 J COMPUT CIVIL ENG JI J. Comput. Civil. Eng. PD JUL PY 1994 VL 8 IS 3 BP 345 EP 358 DI 10.1061/(ASCE)0887-3801(1994)8:3(345) PG 14 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA QA967 UT WOS:A1994QA96700006 ER PT J AU YANCEY, RN BAAKLINI, GY AF YANCEY, RN BAAKLINI, GY TI COMPUTED-TOMOGRAPHY EVALUATION OF METAL-MATRIX COMPOSITES FOR AEROPROPULSION ENGINE APPLICATIONS SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 38th International Gas Turbine and Aeroengine Congress and Exposition CY MAY 24-27, 1993 CL CINCINNATI, OH SP INT GAS TURBINE INST AB Computed tomography (CT) is a powerful evaluation tool for advanced propulsion engine materials and components. CT uses X-rays nondestructively to produce images of two-dimensional slices or planes through an object. This paper will present data from CT investigations of metal-matrix composite (MMC) ring, rod, and coupon structures. Moderate resolution CT data identified density variations within reinforced sections, which were correlated with fiber packing densities. Also, some composite lay-up features were also imaged. High-resolution CT data provided information on fiber spacing and distribution. Correlation with other NDE techniques and destructive analysis was good. CT proved to provide valuable information on the internal state of these metal-matrix composite components. Use of CT during process development of MMCs and the components made from MMCs is encouraged given the results of this study. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP YANCEY, RN (reprint author), ADV RES & APPLICAT CORP,DAYTON,OH 45431, USA. NR 8 TC 0 Z9 0 U1 2 U2 2 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD JUL PY 1994 VL 116 IS 3 BP 635 EP 639 DI 10.1115/1.2906867 PG 5 WC Engineering, Mechanical SC Engineering GA PA464 UT WOS:A1994PA46400026 ER PT J AU AFOLABI, D MEHMED, O AF AFOLABI, D MEHMED, O TI ON CURVE VEERING AND FLUTTER OF ROTATING BLADES SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 38th International Gas Turbine and Aeroengine Congress and Exposition CY MAY 24-27, 1993 CL CINCINNATI, OH SP INT GAS TURBINE INST AB The eigenvalues of rotating blades usually change with rotation speed according to the Stodola-Southwell criterion. Under certain circumstances, the loci of eigenvalues belonging to two distinct modes of vibration approach each other very closely, and it may appear as if the loci cross each other. However, our study indicates that the observable frequency loci of an undamped rotating blade do not cross, but must either repel each other (leading to ''curve veering ''), or attract each other (leading to ''frequency coalescence''). Our results are reached by using standard arguments from algebraic geometry-the theory of algebraic curves and catastrophe theory. We conclude that it is important to resolve an apparent crossing of eigenvalue loci into either a frequency coalescence or a curve veering, because frequency coalescence is dangerous since it leads to flutter, whereas curve veering does not precipitate flutter and is, therefore, harmless with respect to elastic stability. C1 NASA,LEWIS RES CTR,INST COMPUTAT MECH PROPULS,CLEVELAND,OH 44135. RP AFOLABI, D (reprint author), PURDUE UNIV,DEPT MECH ENGN,W LAFAYETTE,IN 47907, USA. NR 27 TC 9 Z9 9 U1 0 U2 3 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD JUL PY 1994 VL 116 IS 3 BP 702 EP 708 DI 10.1115/1.2906876 PG 7 WC Engineering, Mechanical SC Engineering GA PA464 UT WOS:A1994PA46400035 ER PT J AU SPOONER, BS AF SPOONER, BS TI INTRODUCTION - GRAVITATIONAL CELLULAR AND DEVELOPMENTAL BIOLOGY SO JOURNAL OF EXPERIMENTAL ZOOLOGY LA English DT Editorial Material RP SPOONER, BS (reprint author), KANSAS STATE UNIV AGR & APPL SCI,NASA,SPECIALIZED CTR RES & TRAINING GRAVITAT BIOL,DIV BIOL,MANHATTAN,KS 66506, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0022-104X J9 J EXP ZOOL JI J. Exp. Zool. PD JUL 1 PY 1994 VL 269 IS 3 BP 177 EP 177 DI 10.1002/jez.1402690302 PG 1 WC Zoology SC Zoology GA NR282 UT WOS:A1994NR28200001 PM 11536631 ER PT J AU ARMSTRONG, JW CHAPES, SK AF ARMSTRONG, JW CHAPES, SK TI EFFECTS OF EXTRACELLULAR-MATRIX PROTEINS ON MACROPHAGE DIFFERENTIATION, GROWTH, AND FUNCTION - COMPARISON OF LIQUID AND AGAR CULTURE SYSTEMS SO JOURNAL OF EXPERIMENTAL ZOOLOGY LA English DT Article; Proceedings Paper CT 3rd Annual Symposium of the Center-for-Gravitational-Studies-in-Cellular-and-Developmental-Biology: Gravitational Cellular and Developmental Biology CY SEP 29-30, 1993 CL KANSAS STATE UNIV, MANNHATTAN, KS SP KANSAS STATE UNIV, CTR GRAVITAT STUDIES CELLULAR & DEV BIOL HO KANSAS STATE UNIV ID MONOCLONAL-ANTIBODIES; PROGENITOR CELLS; HUMAN-MONOCYTES; IMMUNE CELLS; TNF-ALPHA; FIBRONECTIN; SPACEFLIGHT; SECRETION; LYMPHOCYTES; COLLAGEN AB Both spaceflight and skeletal unloading suppress the haematopoietic differentiation of macrophages (Sonnenfeld et al., Aviat. Space Environ. Med., 61:648-653, 1990; Armstrong et al., J. Appl. Physiol., 75:2734-2739, 1993). The mechanism behind this reduction in haematopoiesis has yet to be elucidated. However, changes in bone marrow extracellular matrix (ECM) may be involved. To further understand the role of ECM products in macrophage differentiation, we have performed experiments evaluating the effects of fibronectin, laminin, collagen type I, and collagen type TV on macrophage development and function. Bone marrow-derived macrophages cultured on four different ECM substrates in liquid culture medium showed less growth than those cultured on plastic. Significant morphological differences were seen on each of the substrates used. Phenotypically and functionally, as measured by class If major histocompatibility molecule (MHCII) expression, MAC-2 expression, and the secretion of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), these macrophages were similar. In contrast, bone marrow-derived macrophages cultured in suspension, using agar, showed no difference in growth when exposed to ECM proteins. However, IL-6 and TNF-alpha secretion was affected by fibronectin, laminin, collagen type I, and collagen type TV in a concentration-dependent manner. We conclude that the ECM products fibronectin, laminin, collagen type I, and collagen type TV have profound effects on macrophage development and function. Additionally, we suggest that an ECM-supplemented agar culture system provides an environment more analogous to in vivo bone marrow than does a traditional liquid culture system. (C) 1994 Wiley-Liss, Inc. C1 KANSAS STATE UNIV AGR & APPL SCI,NASA,SPECIALIZED CTR RES & TRAINING,DIV BIOL,MANHATTAN,KS 66506. NR 33 TC 6 Z9 6 U1 1 U2 3 PU WILEY-LISS PI NEW YORK PA DIV JOHN WILEY & SONS INC 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0022-104X J9 J EXP ZOOL JI J. Exp. Zool. PD JUL 1 PY 1994 VL 269 IS 3 BP 178 EP 187 DI 10.1002/jez.1402690303 PG 10 WC Zoology SC Zoology GA NR282 UT WOS:A1994NR28200002 PM 8014614 ER PT J AU RAMPINO, MR AF RAMPINO, MR TI TILLITES, DIAMICTITES, AND BALLISTIC EJECTA OF LARGE IMPACTS SO JOURNAL OF GEOLOGY LA English DT Article ID CARBONIFEROUS DWYKA FORMATION; LATE PROTEROZOIC GLACIATION; SOUTH-AFRICA; GLACIOMARINE SEDIMENTATION; GOWGANDA FORMATION; ASTEROID IMPACT; WEST-AFRICA; DEPOSITS; BASIN; DEBRIS AB The primary evidence for the temporal and spatial distribution of glaciation prior to the Cenozoic is the occurrence of tillites. These are diamictites (poorly sorted mixtures of very coarse-grained to fine-grained sediments), and associated deposits, which have features considered diagnostic of glacial action. The discovery that many diamictite-bearing sequences were the products of debris flows and related mass flows, with contemporaneous rainout of coarse sediment, has led to the reinterpretation of many tillites as glaciomarine debris-flow deposits. Fallout of ballistic ejecta from the impact of large asteroids or comets can also create large-scale debris flows with simultaneous rainout of debris. Recent calculations of the predicted volume and distribution of impact-generated diamictites suggest that they should be common in the geologic record. Moreover, ballistic debris-flow deposits can apparently exhibit a number of features considered characteristic of glacial deposits (e.g., striated clasts, eroded and striated pavements). The possible confusion between glacial and impact diamictites-a few diamictite deposits formerly interpreted as glacial or questionably glacial in origin are already known to be impact ejecta-suggests that a review of the properties of diamictites of various origins is required. Evidence of shock deformation in diamictites is the most important criterion for determining an impact origin. It is possible that some diamictites identified as glaciogenic may actually be ejecta of large impacts, which may help to explain climatic anomalies, such as Lower Proterozoic tillites at a time of predicted global warmth, and the low-latitude distribution of some Upper Proterozoic glacial deposits. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP RAMPINO, MR (reprint author), NYU,DEPT EARTH SYST SCI,NEW YORK,NY 10003, USA. NR 154 TC 30 Z9 30 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0022-1376 J9 J GEOL JI J. Geol. PD JUL PY 1994 VL 102 IS 4 BP 439 EP 456 PG 18 WC Geology SC Geology GA NX193 UT WOS:A1994NX19300006 ER PT J AU OBERBECK, VR HORZ, F BUNCH, T AF OBERBECK, VR HORZ, F BUNCH, T TI IMPACTS, TILLITES, AND THE BREAKUP OF GONDWANALAND - A 2ND REPLY SO JOURNAL OF GEOLOGY LA English DT Note ID DEPOSITS RP OBERBECK, VR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 25 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0022-1376 J9 J GEOL JI J. Geol. PD JUL PY 1994 VL 102 IS 4 BP 485 EP 489 PG 5 WC Geology SC Geology GA NX193 UT WOS:A1994NX19300010 ER PT J AU LENGYELFREY, D FARRELL, WM STONE, RG BALOGH, A FORSYTH, R AF LENGYELFREY, D FARRELL, WM STONE, RG BALOGH, A FORSYTH, R TI AN ANALYSIS OF WHISTLER WAVES AT INTERPLANETARY SHOCKS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID EARTHS BOW SHOCK; INTER-PLANETARY SHOCKS; PLASMASPHERIC HISS; PLASMA-WAVES; TURBULENCE; FREQUENCY; ULYSSES AB We present an analysis of whistler wave magnetic and electric field amplitude ratios from which we compute wave propagation angles and energies of electrons in resonance with the waves. To do this analysis, we compute the theoretical dependence of ratios of wave components on the whistler wave propagation angle theta for various combinations of orthogonal wave components. Ratios of wave components that would be observed by a spinning spacecraft are determined, and the effects of arbitrary inclinations of the spacecraft to the ambient magnetic field and to the whistler wave vector are studied. This analysis clearly demonstrates that B/E, the ratio of magnetic to electric field amplitudes, cannot be assumed to be the wave index of refraction, contrary to assumptions of some earlier studies. Therefore previous interpretations of whistler wave observations based on this assumption must be reinvestigated. B/E ratios derived using three orthogonal wave components can be used to unambiguously determine theta. Using spin plane observations alone, a significant uncertainty occurs in the determination of theta. Nevertheless, for whistler waves observed downstream of several interplanetary shocks by the Ulysses plasma wave experiment we find that theta is highly oblique. We suggest that the analysis of wave amplitude ratios used in conjunction with traditional stability analyses provide a promising tool for determining which particle distributions and resonances are likely to be dominant contributors to wave growth. C1 UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. RP LENGYELFREY, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DEPT ASTRON,CODE 690,GREENBELT,MD 20771, USA. RI Farrell, William/I-4865-2013 NR 22 TC 18 Z9 19 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 JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1994 VL 99 IS A7 BP 13325 EP 13334 DI 10.1029/94JA00781 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW343 UT WOS:A1994NW34300016 ER PT J AU GHOSH, S GOLDSTEIN, ML AF GHOSH, S GOLDSTEIN, ML TI NONLINEAR EVOLUTION OF A LARGE-AMPLITUDE CIRCULARLY-POLARIZED ALFVEN-WAVE - LOW-BETA SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PARAMETRIC-INSTABILITIES; FILAMENTATION INSTABILITY; MODULATIONAL INSTABILITY; SOLAR-WIND; INCOMPRESSIBLE MAGNETOHYDRODYNAMICS; DECAY INSTABILITY; MAGNETIC-FIELD; TURBULENCE; FLUCTUATIONS; MAGNETOFLUID AB The nature of turbulent cascades arising from the parametric instabilities of a monochromatic field-aligned large-amplitude circularly polarized Alfven wave is investigated via direct numerical simulation for the case of low plasma beta and no wave dispersion. The magnetohydrodynamic code permits nonlinear couplings in the parallel direction to the ambient magnetic field and one perpendicular direction. Compressibility is included in the form of a polytropic equation of state. Anisotropic turbulent cascades, similar to those found in early incompressible two-dimensional simulations, occur after nonlinear saturation of the parallel propagating decay instability. The turbulent spectrum can be divided into three regimes: the lowest wave numbers axe dominated by lower sideband remnants of the parametric process, intermediate wave numbers display nearly incompressible dynamics, and the highest wave numbers are dominated by acoustic turbulence. C1 APPL RES CORP,LANDOVER,MD. RP GHOSH, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. RI Goldstein, Melvyn/B-1724-2008 NR 32 TC 24 Z9 24 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1994 VL 99 IS A7 BP 13351 EP 13362 DI 10.1029/94JA00474 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW343 UT WOS:A1994NW34300018 ER PT J AU HOSPODARSKY, GB GURNETT, DA KURTH, WS KIVELSON, MG STRANGEWAY, RJ BOLTON, SJ AF HOSPODARSKY, GB GURNETT, DA KURTH, WS KIVELSON, MG STRANGEWAY, RJ BOLTON, SJ TI FINE-STRUCTURE OF LANGMUIR-WAVES OBSERVED UPSTREAM OF THE BOW SHOCK AT VENUS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ELECTRON-PLASMA OSCILLATIONS; SOLAR RADIO-BURSTS; MAGNETIC-FIELD; GALILEO FLYBY; FORESHOCK; FREQUENCY; SIMULATION; WIND; GENERATION; TURBULENCE AB Highly structured Langmuir waves, also known as electron plasma oscillations, have been observed in the foreshock of Venus using the plasma wave experiment on the Galileo spacecraft during the gravity assist flyby on February 10, 1990. The Galileo wideband sampling system provides digital electric field waveform measurements at sampling rates up to 201,600 samples per second, much higher than any previous instrument of this type. The main Langmuir wave emission band occurs near the local electron plasma frequency, which was approximately 43 kHz. The Langmuir waves are observed to shift above and below the plasma frequency, sometimes by as much as 20 kHz. The shifts in frequency are closely correlated with the downstream distance from the tangent field line, implying that the shifts are controlled by the electron beam velocity. Considerable fine structure is also evident, with timescales as short as 0.15 ms, corresponding to spatial scales of a few tens of Debye lengths. The frequency spectrum often consists of beat-type waveforms, with beat frequencies ranging from 0.2 to 7 kHz, and in a few cases, isolated wave packets. The peak electric field strengths are approximately 1 mV/m. These field strengths are too small for strongly nonlinear processes to be important. The beat-type waveforms are suggestive of a parametric decay process. C1 UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. JET PROP LAB,PASADENA,CA 91109. RP HOSPODARSKY, GB (reprint author), UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242, USA. RI Kivelson, Margaret/I-9019-2012 OI Kivelson, Margaret/0000-0003-3859-8581 NR 48 TC 29 Z9 29 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1994 VL 99 IS A7 BP 13363 EP 13371 DI 10.1029/94JA00868 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW343 UT WOS:A1994NW34300019 ER PT J AU TSYGANENKO, NA SIBECK, DG AF TSYGANENKO, NA SIBECK, DG TI CONCERNING FLUX EROSION FROM THE DAYSIDE MAGNETOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; WIND DYNAMIC PRESSURE; BIRKELAND CURRENTS; GEOMAGNETIC-FIELD; MAGNETOPAUSE SHAPE; ALIGNED CURRENTS; CURRENT SYSTEM; RING CURRENT; MODEL; MOTION AB The dayside magnetopause moves inward during periods of southward interplanetary magnetic field in response to decreases in the outer magnetospheric magnetic field strength. We consider possible causes for the magnetic field strength decreases and demonstrate that they are consistent with increases in the region 1 Birkeland and cross-tail currents. We reexamine the well-known series of magnetopause crossings by OGO 5 on March 27, 1968, to demonstrate that they provide evidence for two intervals of gradual inward magnetopause motion associated with magnetic flux erosion and also for two intervals of inward magnetopause motion associated with sharp increases in the solar wind dynamic pressure. C1 JOHNS HOPKINS UNIV,APPL PHYS LAB,LAUREL,MD 20723. RP TSYGANENKO, NA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI Sibeck, David/D-4424-2012; Tsyganenko, Nikolai/J-7377-2012 OI Tsyganenko, Nikolai/0000-0002-5938-1579 NR 54 TC 48 Z9 48 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 JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1994 VL 99 IS A7 BP 13425 EP 13436 DI 10.1029/94JA00719 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW343 UT WOS:A1994NW34300025 ER PT J AU ELPHIC, RC BAUMJOHANN, W CATTELL, CA LUHR, H SMITH, MF AF ELPHIC, RC BAUMJOHANN, W CATTELL, CA LUHR, H SMITH, MF TI A SEARCH FOR UPSTREAM PRESSURE PULSES ASSOCIATED WITH FLUX-TRANSFER EVENTS - AND AMPTE ISEE CASE-STUDY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD; MAGNETOSPHERIC RESPONSE; DAYSIDE MAGNETOPAUSE; IRM OBSERVATIONS; RECONNECTION; ISEE-1; PLASMA; WAVES AB On September 19, 1984, the Active Magnetospheric Particle Tracers Explorers (AMPTE) United Kingdom Satellite (UKS) and Ion Release Module (IRM) and ISEE 1 and 2 spacecraft passed outbound through the dayside magnetopause at about the same time. The AMPTE spacecraft pair crossed first and were in the near-subsolar magnetosheath for more than an hour. Meanwhile the ISEE pair, about 5 R(E) to the south, observed flux transfer event (FTE) signatures. We use the AMPTE UKS and IRM plasma and field observations of magnetosheath conditions directly upstream of the subsolar magnetopause to check whether pressure pulses are responsible for the FTE signatures seen at ISEE. Pulses in both the ion thermal pressure and the dynamic pressure are observed in the magnetosheath early on when IRM and UKS are close to the magnetopause, but not later. These large pulses appear to be related to reconnection going on at the magnetopause nearby. AMPTE magnetosheath data far from the magnetopause do not show a pressure pulse correlation with FTEs at ISEE. Moreover, the magnetic pressure and tension effects seen in the ISEE FTEs are much larger than any pressure effects seen in the magnetosheath. A superposed epoch analysis based on small-amplitude peaks in the AMPTE magnetosheath total static pressure (nkT + B2/2mu(o)) hint at some boundary effects, <5 nT peak-to-peak variations in the ISEE 1 and 2 B(N) signature starting about 1 min after the pressure peak epoch. However, these variations are much smaller than the standard deviations of the B(N) field component. Thus the evidence from this case study suggests that upstream magnetosheath pressure pulses do not give rise to FTEs, but may produce very small amplitude signatures in the magnetic field at the magnetopause. C1 MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. TECH UNIV CAROLO WILHELMINA BRAUNSCHWEIG,INST GEOPHYS & METEOROL,D-38106 BRAUNSCHWEIG,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP ELPHIC, RC (reprint author), LOS ALAMOS NATL LAB,SPACE & ATMOSPHER SCI GRP,LOS ALAMOS,NM 87545, USA. RI Baumjohann, Wolfgang/A-1012-2010 OI Baumjohann, Wolfgang/0000-0001-6271-0110 NR 19 TC 12 Z9 12 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1994 VL 99 IS A7 BP 13521 EP 13527 DI 10.1029/94JA00575 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW343 UT WOS:A1994NW34300032 ER PT J AU PARKS, GK FITZENREITER, R OGILVIE, KW HUANG, C ANDERSON, KA DANDOURAS, J FRANK, L LIN, RP MCCARTHY, M REME, H SAUVAUD, JA WERDEN, S AF PARKS, GK FITZENREITER, R OGILVIE, KW HUANG, C ANDERSON, KA DANDOURAS, J FRANK, L LIN, RP MCCARTHY, M REME, H SAUVAUD, JA WERDEN, S TI LOW-ENERGY PARTICLE LAYER OUTSIDE THE PLASMA SHEET BOUNDARY - REPLY SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Note C1 UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. CTR ETUD SPATIALE RAYONNEMENT,F-31029 TOULOUSE,FRANCE. UNIV IOWA,DEPT PHYS,IOWA CITY,IA 52242. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP PARKS, GK (reprint author), UNIV WASHINGTON,GEOPHYS PROGRAM,AK 50,SEATTLE,WA 98195, USA. NR 2 TC 1 Z9 1 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD JUL 1 PY 1994 VL 99 IS A7 BP 13541 EP 13541 DI 10.1029/93JA03425 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW343 UT WOS:A1994NW34300035 ER PT J AU SARAVANAN, N DUYAR, A GUO, TH MERRILL, WC AF SARAVANAN, N DUYAR, A GUO, TH MERRILL, WC TI MODELING SPACE-SHUTTLE MAIN ENGINE USING FEEDFORWARD NEURAL NETWORKS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID NON-LINEAR SYSTEMS; BACKPROPAGATION; IDENTIFICATION AB We present the modeling of the Space Shuttle main engine (SSME) using a feed-forward neural network. The input and output data for modeling are obtained from a nonlinear performance simulation. The SSME is modeled as a system with two inputs and four outputs. The backpropagation algorithm is used to train the neural network by minimizing the squares of the residuals. The inputs to the network are the delayed values of the selected inputs and outputs of the nonlinear simulation. The results obtained from the neural network model are compared with the results obtained from the nonlinear simulation, under two different experimental conditions. The results show that a single neural network can be used to model the dynamics of the SSME. This neural network model can be used for control system design and development, as well as for model-based fault detection studies. C1 NASA,LEWIS RES CTR,ADV CONTROLS TECHNOL BRANCH,CLEVELAND,OH 44135. RP SARAVANAN, N (reprint author), FLORIDA ATLANTIC UNIV,DEPT MECH ENGN,BOCA RATON,FL 33431, USA. NR 29 TC 4 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1994 VL 17 IS 4 BP 641 EP 648 DI 10.2514/3.21250 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PB528 UT WOS:A1994PB52800001 ER PT J AU GAWRONSKI, W AF GAWRONSKI, W TI LINEAR-QUADRATIC CONTROLLER-DESIGN FOR THE DEEP SPACE NETWORK ANTENNAS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB A linear quadratic controller design procedure is proposed for NASA's deep space network antennas. The procedure is developed for an antenna model divided into tracking and flexible subsystems. Controllers for the flexible and tracking parts are designed by separately adjusting the performance index weights. First the weights for the flexible part are adjusted, next the weights for the tracking part are determined, followed by the flexible controller final tune-up. The controller for the flexible part is designed separately for each component; thus the design consists of weight adjustment for small-sized subsystems. The effect of weights on system performance is analytically described in this paper. The procedure is illustrated with the control system design for the recently built DSS-13 34-m dish antenna. RP GAWRONSKI, W (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 11 TC 3 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1994 VL 17 IS 4 BP 655 EP 660 DI 10.2514/3.21252 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PB528 UT WOS:A1994PB52800003 ER PT J AU PHAN, M JUANG, JN HORTA, LG LONGMAN, RW AF PHAN, M JUANG, JN HORTA, LG LONGMAN, RW TI SYSTEM-IDENTIFICATION FROM CLOSED-LOOP DATA WITH KNOWN OUTPUT-FEEDBACK DYNAMICS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper formulates a method to identify the open-loop dynamics of a system operating under closed-loop conditions. The closed-loop excitation data and the feedback dynamics are assumed to be known. Two closed-loop configurations are considered where the system has either a linear output feedback controller or a dynamic output feedback controller. First, the closed-loop excitation data are used to compute the closed-loop Markov parameters, from which the open-loop Markov parameters are recovered from the known feedback dynamics. The Markov parameters are then used to compute a state space representation of the open-loop system. Examples are provided to illustrate the computational steps involved in the proposed closed-loop identification method. C1 LOCKHEED ENGN & SCI CO,LANGLEY PROGRAM OFF,HOUSTON,TX. NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,HAMPTON,VA 23665. COLUMBIA UNIV,DEPT MECH ENGN,NEW YORK,NY 10027. RP PHAN, M (reprint author), PRINCETON UNIV,DEPT MECH & AEROSP ENGN,PRINCETON,NJ 08544, USA. NR 8 TC 11 Z9 11 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1994 VL 17 IS 4 BP 661 EP 669 DI 10.2514/3.21253 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PB528 UT WOS:A1994PB52800004 ER PT J AU SU, TJ JUANG, JN AF SU, TJ JUANG, JN TI DECENTRALIZED CONTROL OF LARGE FLEXIBLE STRUCTURES BY JOINT DECOUPLING SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB This paper presents a novel method to design decentralized controllers for large complex flexible structures by using the idea of joint decoupling. Decoupling of joint degrees of freedom from the interior degrees of freedom is achieved by setting the joint actuator commands to cancel the internal forces exerting on the joint degrees of freedom. By doing so, the interactions between substructures are eliminated. The global structure control design problem is then decomposed into several substructure control design problems. Control commands for interior actuators are set to be localized state feedback using decentralized observers for state estimation. The proposed decentralized controllers can operate successfully at the individual substructure level as well as at the global structure level. Not only control design but also control implementation is decentralized. A two-component mass-spring-damper system is used as an example to demonstrate the proposed method. RP SU, TJ (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT DYNAM BRANCH,HAMPTON,VA 23662, USA. NR 8 TC 3 Z9 5 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1994 VL 17 IS 4 BP 676 EP 684 DI 10.2514/3.21255 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PB528 UT WOS:A1994PB52800006 ER PT J AU MARKLEY, FL NELSON, JD AF MARKLEY, FL NELSON, JD TI ZERO-GYRO SAFEMODE CONTROLLER FOR THE HUBBLE-SPACE-TELESCOPE SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB A safehold mode has been implemented for Hubble Space Telescope that ensures a power-positive and thermally safe state without the use of rate gyros. This paper presents an overview of this Zero-Gyro Sunpoint safemode, followed by details of the algorithm, the control system design, and results of simulations and of an on-orbit test of the algorithm. C1 LOCKHEED MISSILES & SPACE CO INC,SUNNYVALE,CA 94088. RP MARKLEY, FL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GUIDANCE & CONTROL BRANCH,CODE 712,GREENBELT,MD 20771, USA. NR 7 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1994 VL 17 IS 4 BP 815 EP 822 DI 10.2514/3.21271 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PB528 UT WOS:A1994PB52800022 ER PT J AU MILMAN, MH CHU, CC AF MILMAN, MH CHU, CC TI OPTIMIZATION METHODS FOR PASSIVE DAMPER PLACEMENT AND TUNING SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID SELECTION AB The effectiveness of viscous elements in introducing damping in a structure is a function of several variables including their number, their location in the structure, and their physical properties. This paper addresses the questions of the placement of these elements and the selection of their physical parameters via optimization techniques. The paper investigates various metrics to define these optimization problems and compares the damping profiles that are obtained. Both discrete and continuous optimization problems are formulated and solved corresponding, respectively, to the problems of placement of damping elements and to the tuning of their parameters. Particular emphasis is placed on techniques to make feasible the large-scale problems resulting from the optimization formulations. Numerical results involving a lightly damped testbed structure are presented. RP MILMAN, MH (reprint author), JET PROP LAB,GUIDANCE & CONTROL SECT,PASADENA,CA 91109, USA. NR 18 TC 23 Z9 28 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1994 VL 17 IS 4 BP 848 EP 856 DI 10.2514/3.21275 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PB528 UT WOS:A1994PB52800026 ER PT J AU LEE, AY TSUHA, WS AF LEE, AY TSUHA, WS TI COMPONENT MODEL-REDUCTION METHODOLOGY FOR ARTICULATED MULTIFLEXIBLE BODY STRUCTURES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note C1 JET PROP LAB,COMMUN SYST RES SECT,PASADENA,CA 91109. RP LEE, AY (reprint author), JET PROP LAB,GUIDANCE & CONTROL SECT,4800 OAK GROVE DR,MAIL STOP 198-326,PASADENA,CA 91109, USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1994 VL 17 IS 4 BP 864 EP 868 DI 10.2514/3.21279 PG 5 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PB528 UT WOS:A1994PB52800030 ER PT J AU LEE, AY SMYTH, P AF LEE, AY SMYTH, P TI SYNTHESIS OF MINIMUM-TIME FEEDBACK LAWS FOR DYNAMIC-SYSTEMS USING NEURAL NETWORKS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note C1 JET PROP LAB,COMMUN SYST RES,PASADENA,CA 91109. RP LEE, AY (reprint author), JET PROP LAB,GUIDANCE & CONTROL SECT,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 7 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 JUL-AUG PY 1994 VL 17 IS 4 BP 868 EP 870 DI 10.2514/3.21280 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PB528 UT WOS:A1994PB52800031 ER PT J AU TAUBER, ME AF TAUBER, ME TI GUIDANCE FOR AN AEROCAPTURE MANEUVER - COMMENT SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note RP TAUBER, ME (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 2 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 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD JUL-AUG PY 1994 VL 17 IS 4 BP 878 EP 878 PG 1 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA PB528 UT WOS:A1994PB52800035 ER PT J AU HOBISH, MK ARDANUY, PE SALOMONSON, VV AF HOBISH, MK ARDANUY, PE SALOMONSON, VV TI SURFACE IMAGING TECHNOLOGIES FOR NASAS EARTH OBSERVING SYSTEM SO JOURNAL OF IMAGING SCIENCE AND TECHNOLOGY LA English DT Article AB The Earth Observing System (EOS) is the major element in the National Aeronautic and Space Administration's Mission to Planet Earth. It will be a 15-year-long mission, employing space-based instrumentation and in situ measurements to provide a long-term, contiguous, calibrated, and validated data set that addresses geophysical and biochemical phenomena occurring in the Earth system. The EOS suite of satellites includes sun-synchronous, polar-orbiting spacecraft with morning or afternoon equator-crossing times. The EOS-AM series, the first of which is slated for launch in June 1998, will address geophysical and biogeochemical processes occurring at or near the Earth's surface; the EOS-PM platforms will address atmospheric phenomena, including the interaction between clouds and radiation. Synergy and complementarity within and between these and other platforms will play a major role in acquiring high-quality data. We discuss the following instruments: Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Multifrequency Imaging Microwave Radiometer (MIMR), Multiangle Imaging Spectroradiometer (MISR), and Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit/Microwave Humidity Sounder) (AIRS/AMSU/MHS). Instrument heritage, design, capabilities, and realization are discussed in terms of satisfying scientific requirements. We also discuss the synergy resulting from cross-calibration of the instruments and validation of their resulting data products. C1 NASA,GODDARD SPACE FLIGHT CTR,EARTH SCI DIRECTORATE,GREENBELT,MD 20771. RP HOBISH, MK (reprint author), RES & DATA SYST CORP,GREENBELT,MD, USA. NR 8 TC 0 Z9 0 U1 0 U2 1 PU I S & T - SOC IMAGING SCIENCE TECHNOLOGY PI SPRINGFIELD PA 7003 KILWORTH LANE, SPRINGFIELD, VA 22151 SN 8750-9237 J9 J IMAGING SCI TECHN JI J. Imaging Sci. Technol. PD JUL-AUG PY 1994 VL 38 IS 4 BP 301 EP 310 PG 10 WC Imaging Science & Photographic Technology SC Imaging Science & Photographic Technology GA PV023 UT WOS:A1994PV02300002 ER PT J AU SINGH, M BEHRENDT, DR AF SINGH, M BEHRENDT, DR TI REACTIVE MELT INFILTRATION OF SILICON-NIOBIUM ALLOYS IN MICROPOROUS CARBONS SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID CARBIDE; MECHANISM AB Studies of the reactive melt infiltration of silicon-niobium alloys in microporous carbon preforms prepared by the pyrolysis of a polymer precursor have been carried out using modeling, DTA, and melt infiltration. Mercury porosimetry results indicate a very narrow pore size distribution with virtually all the porosity within the carbon preforms open to infiltrants. The morphology and amount of the residual phases (niobium disilicide and silicon) in the infiltrated material can be tailored according to requirements by careful control of the properties (pore size and pore volume) of the porous carbon preforms and alloy composition. The average room temperature four-point flexural strength of a reaction-formed silicon carbide material (made by the infiltration of medium pore size carbon preform with Si-5 at. % Nb alloy) is 290 +/- 40 MPa (42 +/- 6 ksi) and the fracture toughness is 3.7 +/- 0.3 MPa square-root m. The flexural strength decreases at high temperatures due to relaxation of residual thermal stresses and the presence of free silicon in the material. RP SINGH, M (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 16 TC 54 Z9 59 U1 2 U2 15 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 JUL PY 1994 VL 9 IS 7 BP 1701 EP 1708 DI 10.1557/JMR.1994.1701 PG 8 WC Materials Science, Multidisciplinary SC Materials Science GA NU760 UT WOS:A1994NU76000013 ER PT J AU TOTH, RA AF TOTH, RA TI MEASUREMENTS OF (H2O)-O-16 LINE POSITIONS AND STRENGTHS - 11610 TO 12861 CM-1 SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID WATER-VAPOR AB High resolution spectra of (H2O)-O-16 vapor covering the region from 11 610 to 12 861 cm-1 were used to determine experimental values of line positions and strengths of 933 lines, which include vibration-rotation transitions in the (211)-(000), (131)-(000), (310)-(000), (112)-(000), and (031)-(000) bands, from which rotational energy levels in the (211), (131), (310), (112), and (031) vibrational states were obtained. The linestrengths and positions reported here are considered to be a marked improvement over the values listed in the 1986 edition of the HITRAN database and a preliminary listing from this work has been included in the 1993 HITRAN edition. (C) 1994 Academic Press, Inc. RP TOTH, RA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 6 TC 56 Z9 56 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUL PY 1994 VL 166 IS 1 BP 176 EP 183 DI 10.1006/jmsp.1994.1183 PG 8 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA NR333 UT WOS:A1994NR33300018 ER PT J AU TOTH, RA AF TOTH, RA TI THE NU(1) AND NU(3) BANDS OF (H2O)-O-17 AND (H2O)-O-18 - LINE POSITIONS AND STRENGTHS SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID TRANSITION FREQUENCIES; INTENSITIES; SPECTRUM; WATER AB High-resolution spectra of (H2O)-O-17 and (H2O)-O-18 were recorded with a Fourier-transform spectrometer covering transitions in the (100)-(000) and (001)-(000) bands. The measured line positions were used to determine high accuracy values of rotational energy levels in the (100) and (001) vibrational states for the two isotopic species. Measurements of the line strengths were fitted to a model in which 19 transition moment parameters were determined for B-type bands and 8 parameters for the A-type bands for each molecule. The fitting technique did not consider interactions between the (020), (100), and (001) vibrational states. The experimental results provide a more accurate representation of the line positions and strengths than those presently available for these bands. (C) 1994 Academic Press, Inc. RP TOTH, RA (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 18 TC 15 Z9 15 U1 0 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUL PY 1994 VL 166 IS 1 BP 184 EP 203 DI 10.1006/jmsp.1994.1184 PG 20 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA NR333 UT WOS:A1994NR33300019 ER PT J AU PERRIN, A FLAUD, JM CAMYPEYRET, C WINNEWISSER, BP KLEE, S GOLDMAN, A MURCRAY, FJ BLATHERWICK, RD BONOMO, FS MUIRCRAY, DG RINSLAND, CP AF PERRIN, A FLAUD, JM CAMYPEYRET, C WINNEWISSER, BP KLEE, S GOLDMAN, A MURCRAY, FJ BLATHERWICK, RD BONOMO, FS MUIRCRAY, DG RINSLAND, CP TI 1ST ANALYSIS OF THE 3-NU(9) - NU(9), 3-NU(9) - NU(5), AND 3-NU(9) - 2-NU(9) BANDS OF HNO3 - TORSIONAL SPLITTING IN THE NU(9) VIBRATIONAL-MODE SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID NITRIC-ACID; INFRARED-SPECTRUM; LINE-INTENSITIES; 2-NU-9; MICROWAVE; NU-5; H2O2 AB Using Fourier transform spectra recorded at 25 and 12 mum, it has been possible to perform the first analysis of the 3nu9, - 2nu9, 3nu9 - nu5 and 3nu9 - nu9 hot bands of HNO3 located at 392.4 cm-1, 409.8 cm-1, and 830.4 cm-1, respectively. An accurate description of the torsional splitting in the upsilon9 = 3 vibrational state was achieved, leading to the determination of the two torsional band centers E(upsilong=3,1) = 1288.8451 cm-1 and E(upsilong = 3,2) = 1288.9036 cm-1 and to the first determination of the nu9 torsional potential of HNO3. Finally, the 4nu9 - 3nu9, nu5 + nu9 - 2nu9, and nu5 + nu9 - nu9 hot bands were identified for the first time at 375.3-376.1 cm-1, 447.2 cm-1 and 885.424 cm-1 respectively. (C) 1994 Academic Press, Inc. C1 JUSTUS LIEBIG UNIV GIESSEN,INST PHYS CHEM,D-35392 GIESSEN,GERMANY. UNIV DENVER,DEPT PHYS,DENVER,CO 80208. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. RP PERRIN, A (reprint author), UNIV PARIS 06,CNRS,PHYS MOLEC & APPLICAT LAB,TOUR 13,BOITE 76,4 PL JUSSIEU,F-75252 PARIS 05,FRANCE. NR 25 TC 34 Z9 34 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD JUL PY 1994 VL 166 IS 1 BP 224 EP 243 DI 10.1006/jmsp.1994.1187 PG 20 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA NR333 UT WOS:A1994NR33300022 ER PT J AU ESPANA, MD AF ESPANA, MD TI SENSOR BIASES EFFECT ON THE ESTIMATION ALGORITHM FOR PERFORMANCE-SEEKING CONTROLLERS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The performance-seeking-control algorithm (PSC) is designed to continuously optimize the performance of propulsion systems. The PSC uses a nominal model of the propulsion system and estimates, in night, the engine deviation parameters (EDPs) characterizing engine deviations with respect to nominal conditions. In practice, the measurement biases (or model uncertainties) may prevent the estimated EDPs from reflecting the engine's actual off-nominal condition. This factor has a direct impact on the PSC scheme exacerbated by the open-loop character of the algorithm. An observability analysis shows that the biases cannot be estimated together with the EDPs. Moreover, biases and EDPs turn out to have equivalent effects on the measurements, leaving it undecided whether the estimated EDPs represent the actual engine deviation or whether they simply reflect the measurement biases. In this article, the effects produced by unknown measurement biases over the estimation algorithm are evaluated. This evaluation allows for identification of the most critical measurements for application of the PSC algorithm to an F100 engine. RP ESPANA, MD (reprint author), NASA,DRYDEN FLIGHT RES FACIL,NATL RES COUNCIL,EDWARDS AFB,CA 93523, USA. NR 13 TC 11 Z9 11 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1994 VL 10 IS 4 BP 527 EP 532 DI 10.2514/3.23804 PG 6 WC Engineering, Aerospace SC Engineering GA NW968 UT WOS:A1994NW96800012 ER PT J AU MATHUR, SR MADAVAN, NK RAJAGOPALAN, RG AF MATHUR, SR MADAVAN, NK RAJAGOPALAN, RG TI SOLUTION-ADAPTIVE STRUCTURED-UNSTRUCTURED GRID METHOD FOR UNSTEADY TURBOMACHINERY ANALYSIS .1. METHODOLOGY SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID FLOWS; TURBINE; STAGE AB A solution-adaptive method for the time-accurate analysis of two-dimensional flows in multistage turbomachinery is presented. The method employs a hybrid structured-unstructured zonal grid topology in conjunction with appropriate modeling equations and solution techniques in each zone, thus combining the advantages of both structured and unstructured grid methods. The viscous flow region in the immediate vicinity of the airfoils is resolved on structured 0-type grids, while the rest of the domain is discretized using an unstructured mesh of triangular cells. In the inner regions, the Navier-Stokes equations are solved using an implicit, third-order accurate, upwind-biased scheme. The use of both central difference and upwind schemes is explored for the solution of the Euler equations in the outer regions. An efficient and robust grid adaptation strategy, including both grid refinement and coarsening capabilities, is developed for the unstructured grid regions. Methodologies for the accurate, conservative transfer of information at the interface between the structured and unstructured domains, as well as that between two unstructured grids in relative motion, are also developed. For generality, three-dimensional effects of stream-tube contraction are modeled. The numerical methodology is presented in detail in the present article (Part 1). Results obtained using this method and comparisons of these results with experimental data and earlier structured-grid based methods are presented in a companion article (Part II). C1 NASA,AMES RES CTR,MCAT INST,MOFFETT FIELD,CA 94035. RP MATHUR, SR (reprint author), IOWA STATE UNIV SCI & TECHNOL,AMES,IA 50011, USA. NR 26 TC 4 Z9 4 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 JUL-AUG PY 1994 VL 10 IS 4 BP 576 EP 584 DI 10.2514/3.23811 PG 9 WC Engineering, Aerospace SC Engineering GA NW968 UT WOS:A1994NW96800019 ER PT J AU MATHUR, SR MADAVAN, NK RAJAGOPALAN, RG AF MATHUR, SR MADAVAN, NK RAJAGOPALAN, RG TI SOLUTION-ADAPTIVE STRUCTURED-UNSTRUCTURED GRID METHOD FOR UNSTEADY TURBOMACHINERY ANALYSIS .2. RESULTS SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID ROTOR-STATOR INTERACTION; TURBINE AB A solution-adaptive method for the time-accurate analysis of two-dimensional flows in multistage turbomachinery is presented. The method employs a hybrid structured-unstructured zonal grid topology in conjunction with appropriate modeling equations and solution techniques in each zone, thus combining the advantages of both structured and unstructured grid methods. An efficient and robust grid adaptation strategy is also used for the unstructured grid regions. The numerical methodology is presented in detail in Part I of this article. Results obtained using this method for different turbomachine flow configurations are presented in this article. The numerical results compare well with available experimental data and other structured grid based simulations. C1 NASA,AMES RES CTR,MCAT INST,MOFFETT FIELD,CA 94035. RP MATHUR, SR (reprint author), IOWA STATE UNIV SCI & TECHNOL,AMES,IA 50011, USA. NR 4 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD JUL-AUG PY 1994 VL 10 IS 4 BP 585 EP 592 DI 10.2514/3.23812 PG 8 WC Engineering, Aerospace SC Engineering GA NW968 UT WOS:A1994NW96800020 ER PT J AU MISHCHENKO, MI AF MISHCHENKO, MI TI ASYMMETRY PARAMETERS OF THE PHASE FUNCTION FOR DENSELY PACKED SCATTERING GRAINS SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID BIDIRECTIONAL REFLECTANCE SPECTROSCOPY; NONSPHERICAL TSCHEBYSCHEFF PARTICLES; AXIALLY-SYMMETRICAL PARTICLES; WAVE RADAR SCATTERING; LIGHT-SCATTERING; RADIATIVE-TRANSFER; OPTICAL-PROPERTIES; SPECTRAL ALBEDO; MULTIPLE-SCATTERING; WEAK LOCALIZATION AB Spatial correlation among densely packed particles can substantially change their single-scattering properties, thus making questionable the applicability of the independent scattering approximation in calculations of light scattering by planetary regoliths. The same problem arises in geophysics in light scattering computations for snow, frosts, and bare soil. In this paper, we use a dense-medium light-scattering theory based on the introduction of the static structure factor to calculate asymmetry parameters of the phase function for densely packed particles with real refractive indices 1.31 and 1.66, approximating water ice and soil particles, respectively, and imaginary refractive indices 0, 0.01, and 0.3. For sparsely distributed, independently scattering grains, the calculated asymmetry parameters are always positive and always larger than those for densely packed particles. For densely packed grains, the asymmetry parameters may be negative but only for radius-to-wavelength ratios from about 0.1 to about 0.4. With decreasing particle size, the calculated asymmetry parameters tend to zero independently of the compaction state. In the geometrical optics regime, the asymmetry parameters for densely packed scatterers are positive and very close to those for independently scattering grains. These results may have important implications for remote sensing of the Earth and solid planetary surfaces. In particular, it is demonstrated that negative asymmetry parameters derived with some approximate multiple-scattering theories may be physically irrelevant and can be the result of using an inaccurate bidirectional reflection function combined with the ill-conditionality of the inverse scattering problem. RP MISHCHENKO, MI (reprint author), NASA,GODDARD INST SPACE STUDIES,HUGHES STX CORP,NEW YORK,NY 10025, USA. RI Mishchenko, Michael/D-4426-2012 NR 74 TC 91 Z9 91 U1 3 U2 7 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 JUL PY 1994 VL 52 IS 1 BP 95 EP 110 DI 10.1016/0022-4073(94)90142-2 PG 16 WC Optics; Spectroscopy SC Optics; Spectroscopy GA PB533 UT WOS:A1994PB53300009 ER PT J AU COLBAUGH, R SERAJI, H GLASS, K AF COLBAUGH, R SERAJI, H GLASS, K TI DECENTRALIZED ADAPTIVE-CONTROL OF MANIPULATORS SO JOURNAL OF ROBOTIC SYSTEMS LA English DT Article ID REDUNDANT MANIPULATORS; CONFIGURATION CONTROL; ROBOT MANIPULATORS; CONTROL LAWS; SYSTEMS; TRACKING AB This article presents two new adaptive schemes for motion control of robot manipulators. The first controller possesses a partially decentralized structure in which the control input for each task variable is computed based on information concerning only that variable and on two ''scaling factors'' that depend on the other task variables. The need for these scaling factors is eliminated in the second controller by exploiting the underlying topology of the robot configuration space, and this refinement permits the development of a completely decentralized adaptive control strategy. The proposed controllers are computationally efficient, do not require knowledge of either the mathematical model or the parameter values of the robot dynamics, and are shown to be globally stable in the presence of bounded disturbances. Furthermore, the control strategies are general and can be implemented for either position regulation or trajectory tracking in joint-space or task-space. Computer simulation results are given for a PUMA 762 manipulator, and these demonstrate that accurate and robust trajectory tracking is achievable using the proposed controllers. Experimental results are presented for a PUMA 560 manipulator and confirm that the proposed schemes provide simple and effective real-time controllers for accomplishing high-performance trajectory tracking. (C) 1994 John Wiley & Sons, Inc. C1 NEW MEXICO STATE UNIV, DEPT MECH ENGN, LAS CRUCES, NM 88003 USA. JET PROP LAB, PASADENA, CA 91109 USA. RP GLASS, K (reprint author), NEW MEXICO STATE UNIV, DEPT MECH ENGN, LAS CRUCES, NM 88003 USA. NR 34 TC 16 Z9 16 U1 0 U2 1 PU JOHN WILEY & SONS INC PI HOBOKEN PA 111 RIVER ST, HOBOKEN, NJ 07030 USA SN 0741-2223 J9 J ROBOTIC SYST JI J. Robot. Syst. PD JUL PY 1994 VL 11 IS 5 BP 425 EP 440 DI 10.1002/rob.4620110508 PG 16 WC Robotics SC Robotics GA NR640 UT WOS:A1994NR64000007 ER PT J AU RAULT, DFG AF RAULT, DFG TI AERODYNAMIC CHARACTERISTICS OF THE MAGELLAN SPACECRAFT IN THE VENUS UPPER-ATMOSPHERE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The aerodynamic flight characteristics of the Magellan spacecraft in the Venus atmosphere are computed at a nominal altitude of 140 km over a wide range of incidence angles and roll angles. Computational methods are described that can be used to simulate flowfields in the transition and free-molecule domains over vehicles of arbitrarily complex geometry. Values of the drag, lift, and transverse forces and of the pitch, yaw, and roll moments are given for incidence angles of -60 to 60 deg and roll angles of 0 to 360 deg. Transitional-flow effects are quantified and shown to be small, but not negligible and should be accounted for if high accuracy is required. RP RAULT, DFG (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 14 TC 2 Z9 2 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 537 EP 542 DI 10.2514/3.26475 PG 6 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600001 ER PT J AU TARTABINI, PV STRIEPE, SA POWELL, RW AF TARTABINI, PV STRIEPE, SA POWELL, RW TI ABORT OPTIONS FOR POTENTIAL MARS MISSIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Mars trajectory design options were examined that would accommodate a premature termination of a nominal manned opposition class mission for opportunities between 2010 and 2025. A successful abort must provide a safe return to Earth in the shortest possible time consistent with mission constraints. In this study, aborts that provided a minimum increase in the initial vehicle mass in low Earth orbit (IMLEO) were identified by locating direct transfer nominal missions and nominal missions including an outbound or inbound Venus swing-by that minimized IMLEO. The ease with which these missions could be aborted while meeting propulsion and time constraints was investigated by examining free return (unpowered) and powered aborts. Further reductions in trip time were made to some aborts by the addition or removal of an inbound Venus swing-by. The results show that, although few free return aborts met the specified constraints, 85% of each nominal mission could be aborted as a powered abort without an increase in propellant. Also, in many cases, the addition or removal of a Venus swing-by increased the number of abort opportunities or decreased the total trip time during an abort. RP TARTABINI, PV (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23681, USA. NR 12 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 543 EP 549 DI 10.2514/3.26476 PG 7 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600002 ER PT J AU BLANCHARD, RC LARMAN, KT MOATS, CD AF BLANCHARD, RC LARMAN, KT MOATS, CD TI RAREFIED-FLOW SHUTTLE AERODYNAMICS FLIGHT MODEL SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID ACCELEROMETER PACKAGE EXPERIMENT AB A model of the Shuttle Orbiter rarefield-flow aerodynamic force coefficients has been derived from the ratio of flight acceleration measurements. The in-situ, low-frequency (<1 Hz), low-level (approximately 1 x 10(-6)g) acceleration measurements are made during atmospheric re-entry. The experiment equipment designed and used for this task is the High Resolution Accelerometer Package (HiRAP), one of the sensor packages in the Orbiter Experiments Program. To date, 12 HiRAP re-entry mission data sets spanning a period of about 10 years have been processed. The HiRAP-derived aerodynamics model is described in detail. The model includes normal and axial hypersonic continuum coefficient equations as functions of angle of attack, body-flap deflection, and elevon deflection. Normal and axial free molecule flow coefficient equations as a function of angle of attack are also presented, along with flight-derived rarefield-flow transition bridging formulae. Comparisons are made between the aerodynamics model, data from the latest Orbiter Operational Aerodynamic Design Data Book, applicable computer simulations, and wind-tunnel data. C1 LOCKHEED ENGN & SCI CO,DEPT SPACE & SYST ENGN,HAMPTON,VA 23666. RP BLANCHARD, RC (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,MAIL STOP 366,HAMPTON,VA 23681, USA. NR 20 TC 4 Z9 5 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 JUL-AUG PY 1994 VL 31 IS 4 BP 550 EP 556 DI 10.2514/3.26477 PG 7 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600003 ER PT J AU BLANCHARD, RC OZOROSKI, TA NICHOLSON, JY AF BLANCHARD, RC OZOROSKI, TA NICHOLSON, JY TI SHUTTLE UPPER-ATMOSPHERE MASS-SPECTROMETER EXPERIMENTAL FLIGHT RESULTS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Calibrated pressure measurements for species with mass-to-charge ratios up to 50 amu/e- were obtained from the shuttle upper atmosphere mass spectrometer experiment during re-entry on the STS-35 mission. The principal experimental objective is to obtain measurements of freestream density in the hypersonic rarefield flow flight regime. Data were collected from 180 to about 87 km. However, data above 115 km were contaminated from a source of gas emanating from pressure transducers connected in parallel to the mass spectrometer. At lower altitudes, the pressure transducer data are compared to the mass spectrometer total pressure with excellent agreement. Near the orifice entrance, a significant amount of CO2 was generated from chemical reactions. The freestream density in the rarefield flow flight regime is calculated using an orifice pressure coefficient model based upon direct simulation Monte Carlo results. This density, when compared with the 1976 U.S. Standard Atmosphere model, exhibits the wavelike nature seen on previous flights using accelerometry. Selected spectra are presented at higher altitudes (320 km) showing the effects of the ingestion of gases from a forward fuselage fuel dump. C1 VIGYAN INC,HAMPTON,VA 23666. RP BLANCHARD, RC (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681, USA. NR 15 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 562 EP 568 DI 10.2514/3.26479 PG 7 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600005 ER PT J AU HEARD, WL LAKE, MS AF HEARD, WL LAKE, MS TI NEUTRAL BUOYANCY EVALUATION OF EXTRAVEHICULAR ACTIVITY ASSEMBLY OF A LARGE PRECISION REFLECTOR SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB A procedure that enables astronauts in extravehicular activity (EVA) to perform efficient on-orbit assembly of large paraboloidal precision reflectors is presented. The procedure and associated hardware are verified in simulated 0-g (neutral buoyancy) assembly tests of a 14-m-diam precision reflector mockup. The test article represents a precision reflector having a reflective surface that is segmented into 37 individual panels. The panels are supported on a doubly curved tetrahedral truss consisting of 315 struts. The entire truss and seven reflector panels were assembled in 3 h and 7 min by two pressure-suited test subjects. The average time to attach a panel was 2 min and 3 s. These efficient assembly times were achieved because all hardware and assembly procedures were designed to be compatible with EVA assembly capabilities. RP HEARD, WL (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT MECH,MAIL STOP 199,HAMPTON,VA 23681, USA. NR 11 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 569 EP 577 DI 10.2514/3.26480 PG 9 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600006 ER PT J AU WHITE, SM AF WHITE, SM TI RADIATION CONTROL WITH SELECTIVELY REFLECTIVE OVERCOATS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SCATTERING; EXTINCTION AB Selectively reflective overcoats can be used to significantly reduce the temperature of a heated surface under conditions where short-wavelength radiation is the predominant mode of heat transfer to the surface and the total heating is below the melting or ablation limit. In addition, these overcoats can be used to detect and characterize radiation. Theoretical models are used to predict the optical properties of selectively reflective overcoats on an opaque substrate, such as metal or reaction-cured glass. The computed surface reflectance is compared with experimental data. The predicted optical properties of selectively reflective overcoats are used to compute the reduction in surface temperature attainable with this strategy. Design curves are presented for investigating selectively reflective overcoats of different materials. RP WHITE, SM (reprint author), NASA,AMES RES CTR,THERMAL PROTECT MAT BRANCH,MOFFETT FIELD,CA 94035, USA. NR 25 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 642 EP 648 DI 10.2514/3.26490 PG 7 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600016 ER PT J AU DEGROH, KK BANKS, BA AF DEGROH, KK BANKS, BA TI ATOMIC-OXYGEN UNDERCUTTING OF LONG-DURATION EXPOSURE FACILITY ALUMINIZED-KAPTON MULTILAYER INSULATION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Atomic-oxygen undercutting is a potential threat to vulnerable spacecraft materials which have atomic-oxygen protective coatings. Such undercutting is due to the atomic-oxygen attack of oxidizable materials at microscopic defects in the protective coatings. These defects occur during fabrication and handling, or from micrometeroid and debris bombardment in space. An aluminized-polyimide Kapton multilayer insulation sample that was located on the leading edge of the Long Duration Exposure Facility has been used to study low Earth orbit atomic-oxygen undercutting. Cracks in the aluminized coating located around vent holes provided excellent defect sites for the evaluation of atomic-oxygen undercutting. The experimentally observed undercut profiles were compared to predictions from Monte Carlo models for normal incident space ram atomic-oxygen attack. The shape of the undercut profile was found to vary with crack width, which is proportional to the number of oxygen atoms entering the crack. The resulting profiles of atomic-oxygen undercutting which occurred on the aluminized-Kapton sample indicated wide undercut cavities in spite of the fixed ram orientation. Potential causes of the observed undercutting are presented. Implications of the undercutting profiles relevant to Space Station Freedom are also discussed. RP DEGROH, KK (reprint author), NASA,LEWIS RES CTR,DIV POWER TECHNOL,ELECTROPHYS BRANCH,MS 309-2,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 12 TC 56 Z9 56 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 656 EP 664 DI 10.2514/3.26492 PG 9 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600018 ER PT J AU HENIZE, KG ONEILL, CA MULROONEY, MK ANZMEADOR, P AF HENIZE, KG ONEILL, CA MULROONEY, MK ANZMEADOR, P TI OPTICAL-PROPERTIES OF ORBITAL DEBRIS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This paper discusses the albedos and phase angle effects found for 400 members of seven debris swarms using observations obtained in 1990 and 1991 with the NASA Johnson Space Center charge couple device-equipped portable Schmidt telescope. The mean albedo derived by comparing optical brightnesses with average radar cross sections (RCSs) is 10%. The standard deviation in log albedo is 0.35 if the RCSs are assumed to contribute equally to the scatter. Forty objects are sufficiently free of tumble or aspect angle effects to yield consistent phase function slopes. These range from specular in nature (zero slope) through lambertian (moderate slope) to lunar (steep slope) with the mean lying midway between specular and lambertian. Swarm-to-swarm comparison shows the Cosmos 1375 debris to have unusually small scatter in albedo and the Spot 1/Viking debris to have unusually bright albedos. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. RP HENIZE, KG (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE SCI BRANCH,HOUSTON,TX 77058, USA. NR 10 TC 1 Z9 1 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 671 EP 677 DI 10.2514/3.26494 PG 7 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600020 ER PT J AU SUSKO, M AF SUSKO, M TI JIMSPHERE AND RADAR WIND PROFILER TURBULENCE INDICATORS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The primary objective of this paper is to report on the research and technology in identifying wind and turbulent regions from the surface to 16 km (9.94 mi) by the FPS-16 radar/Jimpshere system and to use these wind and turbulent assessments to validate NASA's 50-MHz Radar Wind Profiler. Eleven wind profiles obtained from two Space Shuttle launches, STS-37 and STS-43, during the day of launch were compared. Comparative measurements of the Jimsphere and the Wind Profiler for the vertical gradient (turbulence), Richardson number, stability parameter, scalar wind, and the turbulence probability index show very good agreement between the two sensors. Wind profile statistics from the two wind sensors were compared at a 150-m wavelength. This important calculation of 150-m wavelength was obtained by computing autospectra, cross-spectra, and coherence squared spectra from 20 Jimsphere balloons tracked simultaneously by FPQ-14 and FPS-16 radars. It is further demonstrated that the prototype wind profiler is an excellent monitoring device illustrating the measurements of the winds within 1/2 h of launch zero (L-O). This fills in the time gap of wind profiles closer to L-O because during the Space Shuttle launches, the ascent wind loads are computed 2 h before launch, based on winds aloft obtained by the Jimsphere 2.0 h before liftoff. This increases the probability of a successful mission. RP SUSKO, M (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,EARTH SYST OBSERVING BRANCH,HUNTSVILLE,AL 35812, USA. NR 15 TC 0 Z9 0 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 678 EP 683 DI 10.2514/3.26495 PG 6 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600021 ER PT J AU ROBERTSON, JB AF ROBERTSON, JB TI EFFECTS OF SPACE EXPOSURE ON PYROELECTRIC INFRARED DETECTORS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note RP ROBERTSON, JB (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 1 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 701 EP 703 DI 10.2514/3.26498 PG 3 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600024 ER PT J AU WERCINSKI, PF LYNE, JE AF WERCINSKI, PF LYNE, JE TI MARS AEROCAPTURE - EXTENSION AND REFINEMENT SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note C1 UNIV TENNESSEE,DEPT MECH & AEROSP ENGN,KNOXVILLE,TN 37996. RP WERCINSKI, PF (reprint author), NASA,AMES RES CTR,DIV THERMOSCI,MOFFETT FIELD,CA 94035, USA. RI Lyne, James/E-6363-2011 NR 9 TC 6 Z9 6 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 703 EP 705 DI 10.2514/3.26499 PG 3 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600025 ER PT J AU RAMACHANDRAN, N DOWNEY, JP AF RAMACHANDRAN, N DOWNEY, JP TI 3-DIMENSIONAL NUMERICAL INVESTIGATION OF GRAVITATIONAL AND SOLUTAL EFFECTS IN A CYLINDRICAL CELL (VOL 31, PG 304, 1994) SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Correction, Addition RP RAMACHANDRAN, N (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD JUL-AUG PY 1994 VL 31 IS 4 BP 712 EP 712 DI 10.2514/3.55672 PG 1 WC Engineering, Aerospace SC Engineering GA PF146 UT WOS:A1994PF14600029 ER PT J AU CIOS, KJ BAAKLINI, GY VARY, A TJIA, RE AF CIOS, KJ BAAKLINI, GY VARY, A TJIA, RE TI RADIAL BASIS FUNCTION NETWORK LEARNS CERAMIC PROCESSING AND PREDICTS RELATED STRENGTH AND DENSITY SO JOURNAL OF TESTING AND EVALUATION LA English DT Article DE CERAMICS; NEURAL NETWORKS; SILICON NITRIDE ID STRUCTURAL CERAMICS AB Radial basis function (RBF) neural networks were trained using the data from 273 Si3N4 modulus of rupture (MOR) bars that were tested at room temperature and 135 MOR bars that were tested at 1370-degrees-C. Milling time, sintering time, and sintering gas pressure were the processing parameters used as the input features. Flexural strength and density were the outputs by which the RBF networks were assessed. The ''nodes at data points'' method was used to set the hidden layer centers and output layer training used the gradient descent method. The RBF network predicted strength with an average error of less than 12% and density with an average error of less than 2%. Further, the RBF network demonstrated a potential for optimizing and accelerating the development and processing of emerging ceramic materials. C1 UNIV TOLEDO,TOLEDO,OH 43606. RP CIOS, KJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 8 TC 2 Z9 2 U1 0 U2 0 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0090-3973 J9 J TEST EVAL JI J. Test. Eval. PD JUL PY 1994 VL 22 IS 4 BP 343 EP 350 PG 8 WC Materials Science, Characterization & Testing SC Materials Science GA NV805 UT WOS:A1994NV80500007 ER PT J AU BUNTINE, WL BURCKERT, HJ AF BUNTINE, WL BURCKERT, HJ TI ON SOLVING EQUATIONS AND DISEQUATIONS SO JOURNAL OF THE ACM LA English DT Article DE DEFINITE CLAUSE; E-DISUNIFICATION; E-UNIFICATION; EQUATIONAL THEORY; INEQUATIONS; LOGIC PROGRAMMING; SOLVING EQUATIONS AND DISEQUATIONS ID COMPLETE-SETS; UNIFICATION AB We are interested in the problem of solving a system [s(i) = t(i): 1 less-than-or-equal-to i less-than-or-equal-to n, p(j) not-equal q(j): 1 less-than-or-equal-to j less-than-or-equal-to m] of equations and disequations, also known as disunification. Solutions to disunification problems are substitutions for the variables of the problem that make the two terms of each equation equal, but leave those of the disequations different. We investigate this in both algebraic and logical contexts where equality is defined by an equational theory and more generally by a definitive clause equality theory E. We show how E-disunification can be reduced to E-unification, that is, solving equations only, and give a disunification algorithm for theories given a unification algorithm. In fact, this result shows that for theories in which the solutions of all unification problems can be represented by finitely many substitutions, the solutions of all disunification problems can also be represented finitely. We sketch how disunification can be applied to handle negation in logic programming with equality in a similar style to Colmerauer's logic programming with rational trees, and to represent many solutions to AC-unification problems by a few solutions to ACI-disunification problems. C1 GERMAN RES CTR ARTIFICIAL INTELLIGENCE,D-66123 SAARBRUCKEN 11,GERMANY. RP BUNTINE, WL (reprint author), NASA,AMES RES CTR,MAIL STOP 244-17,MOFFETT FIELD,CA 94035, USA. OI Buntine, Wray/0000-0001-9292-1015 NR 77 TC 8 Z9 8 U1 0 U2 1 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0004-5411 J9 J ACM JI J. ACM PD JUL PY 1994 VL 41 IS 4 BP 591 EP 629 DI 10.1145/179812.179813 PG 39 WC Computer Science, Hardware & Architecture; Computer Science, Information Systems; Computer Science, Software Engineering; Computer Science, Theory & Methods SC Computer Science GA PG186 UT WOS:A1994PG18600001 ER PT J AU HOLT, RG AF HOLT, RG TI SEARCHING FOR THE 2ND-HARMONIC SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Letter ID AIR BUBBLES; GAS-BUBBLES; COOPERATIVE RADIATION; ACOUSTIC-WAVES; LIQUIDS; OSCILLATIONS; CAVITATION; SCATTERING; WATER AB To mathematically model the oscillations of a spherical bubble, either the time-dependent volume V(t) or the radius R(t) can be used as the dependent variable. A recent exchange between the advocates of the volume approach [E. A. Zabolotskaya, J. Acoust. Sec, Am, 94, 2448 (1993)] and the radius approach [J. Wu and G. Du, J. Acoust. Sec. Am. 94, 2446 (1993)] concerns an apparent discrepancy in the predicted nonlinear acoustic emissions from a bubble subject to a time-periodic external pressure field. This Letter attempts to resolve the discrepancy via an examination of the arguments offered by both sides. In addition, some general comments on nonlinear harmonic and subharmonic emissions from acoustically forced bubble oscillations are presented. RP HOLT, RG (reprint author), CALTECH,JET PROP LAB,MS 183-401,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Holt, Ray/G-5677-2010 NR 24 TC 1 Z9 1 U1 0 U2 1 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 JUL PY 1994 VL 96 IS 1 BP 594 EP 596 DI 10.1121/1.410448 PG 3 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA NW521 UT WOS:A1994NW52100067 ER PT J AU BLANKEN, CL PAUSDER, HJ AF BLANKEN, CL PAUSDER, HJ TI INVESTIGATION OF THE EFFECTS OF BANDWIDTH AND TIME-DELAY ON HELICOPTER ROLL-AXIS HANDLING QUALITIES SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB Several years of cooperative research conducted under the U.S./German Memorandum of Understanding (MOU) in helicopter aeromechanics have recently resulted in a successful handling qualities study. The focus of this cooperative research has been the effect of time delays in a high bandwidth vehicle on handling qualities. The jointly performed study included the use of U.S. ground-based simulation and German in-flight simulation facilities. The NASA-Ames Vertical Motion Simulator (VMS) was used to develop a high bandwidth slalom tracking task which took into consideration the constraints of the facilities, The VMS was also used to define a range of tbe test parameters and to perform initial handling qualities evaluations, The flight tests were conducted using DLR's variable-stability BO 105 S3 Advanced Technology Testing Helicopter System (ATTHeS). Configurations included a rate command and an attitude command response system with added time delays of up to 100 milliseconds over the baseline and band width values between 1.5 and 4.5 rad/sec. Sixty-six evaluations were performed in about 25 hours of flight time during ten days of testing. The results indicate a need to more tightly constrain the allowable rob aa;is phase delay for the Level 1 and Level 2 requirements in the U.S. Army's specification for helicopter handling qualities, ADS-33C. C1 DEUTSCH FORSCH ANSTALT LUFT & RAUMFAHRT EV,INST FLUGMECH,BRAUNSCHWEIG,GERMANY. RP BLANKEN, CL (reprint author), USA,AVIAT & TROOP COMMAND,AMES RES CTR,MOFFETT FIELD,CA, USA. NR 23 TC 4 Z9 4 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1994 VL 39 IS 3 BP 24 EP 33 PG 10 WC Engineering, Aerospace SC Engineering GA RN422 UT WOS:A1994RN42200003 ER PT J AU BRENTNER, KS BURLEY, CL MARCOLINI, MA AF BRENTNER, KS BURLEY, CL MARCOLINI, MA TI SENSITIVITY OF ACOUSTIC PREDICTIONS TO VARIATION OF INPUT PARAMETERS SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB Rotor noise prediction codes predict the thickness and loading noise produced by a helicopter rotor, given the blade motion, rotor operating conditions, and fluctuating force distribution over the blade surface. However, the criticality of these various inputs, and their respective effects on the predicted acoustic field, have never been fully addressed, This paper examines the importance of these inputs, and the sensitivity of the acoustic predictions to a variation of each parameter The effects of collective and cyclic pitch, as well as coning and cyclic flapping, are presented, Blade loading inputs are examined to determine the necessary spatial and temporal resolution, as well as the importance of the chordwise distribution, The acoustic predictions show regions in the acoustic field where significant errors occur when simplified blade motions or blade loadings are used, An assessment of the variation in the predicted acoustic field is balanced by a consideration of CPU time necessary for the various approximations, RP BRENTNER, KS (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 15 TC 4 Z9 4 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1994 VL 39 IS 3 BP 43 EP 52 PG 10 WC Engineering, Aerospace SC Engineering GA RN422 UT WOS:A1994RN42200005 ER PT J AU MOAS, E BOITNOTT, RL GRIFFIN, OH AF MOAS, E BOITNOTT, RL GRIFFIN, OH TI AN ANALYTICAL AND EXPERIMENTAL INVESTIGATION OF THE RESPONSE OF THE CURVED, COMPOSITE FRAME SKIN SPECIMENS SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB Six-foot diameter, semicircular graphite/epoxy specimens representative of generic aircraft frames were loaded quasistatically to determine their load response and failure mechanisms for large deflections that occur in airplane crashes, These frame/skin specimens consisted of a cylindrical skin section co-cured with a semicircular I-frame. The skin provided the necessary lateral stiffness to keep deformations in the plane of the frame in order to realistically represent deformations as they occur in actual fuselage structures, Various frame laminate stacking sequences and geometries were evaluated by statically loading the specimen until multiple failures occurred, Two analytical methods were compared for modeling the frame/skin specimens: a two-dimensional shed finite element analysis and a one-dimensional, closed-form, curved beam solution derived using an energy method, Flange effectivities were included in the beam analysis to account for the curling phenomenon that occurs in thin flanges of curved beams. Good correlation was obtained between experimental results and the analytical predictions of the linear response of the frames prior to the initial failure, The specimens were found to be useful for evaluating composite frame designs, C1 LANGLEY RES CTR,USA,RES LAB,VEHICLE STRUCT DIRECTORATE,HAMPTON,VA. VIRGINIA POLYTECH INST & STATE UNIV,COLL ENGN,BLACKSBURG,VA 24061. RP MOAS, E (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23666, USA. NR 14 TC 1 Z9 1 U1 0 U2 0 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD JUL PY 1994 VL 39 IS 3 BP 58 EP 66 PG 9 WC Engineering, Aerospace SC Engineering GA RN422 UT WOS:A1994RN42200007 ER PT J AU SMITH, GL RUTAN, D AF SMITH, GL RUTAN, D TI SPATIAL VARIABILITY OF OUTGOING LONGWAVE RADIATION SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID GENERAL-CIRCULATION MODEL; BAROCLINIC WAVE-GUIDES; FLUCTUATION STATISTICS; BUDGET EXPERIMENT; SATELLITE DATA; ALGORITHMS; SCALES; ERBE AB Data from the Earth Radiation Budget Experiment scanning radiometer aboard the NOAA-9 operational meteorological satellite are used to investigate the spatial variability of outgoing longwave radiation (OLR). Daily and monthly radiation maps at 2.5-degrees latitude-longitude scale are used as a basis for the study. The regions of greatest variability are in the tropics and subtropics. Storm tracks such as the South Pacific convergence zone appear as regions of high OLR variability. Spatial spectra in longitude show two regimes of OLR. At large scales (wavenumbers less than 6), the spatial spectrum is flat, For wavenumbers greater than 10, the spectra decrease as wavenumber to the -3 power. The spatial spectrum of daily anomalies from the mean is a strong function of latitude and season, with interesting features. Correlations of daily anomalies from the monthly mean decrease exponentially in latitude but have a damped-wave structure in longitude. The spatial variability of the daily maps, as measured by degree variance, have 10 times the power at degree 24 than the monthly maps, but at scales between 1 and 10, the degree variance is practically the same for daily as for monthly. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA. RP SMITH, GL (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,MAIL STOP 420,HAMPTON,VA 23665, USA. NR 24 TC 5 Z9 6 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 JUL 1 PY 1994 VL 51 IS 13 BP 1808 EP 1822 DI 10.1175/1520-0469(1994)051<1808:SVOOLR>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NX581 UT WOS:A1994NX58100003 ER PT J AU YOUNG, RE WALTERSCHEID, RL SCHUBERT, G PFISTER, L HOUBEN, H BINDSCHADLER, DL AF YOUNG, RE WALTERSCHEID, RL SCHUBERT, G PFISTER, L HOUBEN, H BINDSCHADLER, DL TI CHARACTERISTICS OF FINITE-AMPLITUDE STATIONARY GRAVITY-WAVES IN THE ATMOSPHERE OF VENUS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID HYDROSTATIC MOUNTAIN WAVES; TURBULENCE; BREAKDOWN AB This paper extends the study of stationary gravity waves generated near the surface of Venus reported previously by Young et al. to include finite amplitude effects associated with large amplitude waves. Waves are forced near the surface of Venus by periodic forcing. The height-dependent profiles of static stability and mean wind in the Venus atmosphere play a very important role in the evolution of the nonlinear behavior of the waves, just as they do in the linear wave solutions. Certain wave properties are qualitatively consistent with linear wave theory, such as wave trapping, resonance, and wave evanescence for short horizontal wavelengths. However, the finite amplitude solutions also exhibit many other interesting features. In particular, for forcing amplitudes representative of those that could be expected in mountainous regions such as Aphrodite Terra, waves generated near the surface can reach large amplitudes at and above cloud levels, with clear signatures in the circulation pattern. At still higher levels, the waves can reach large enough amplitude to break, unless damping rates above the clouds are sufficient to lin-tit wave amplitude growth. Well below cloud levels the waves develop complex flow patterns as the result of finite amplitude wave-wave interactions, and waves are generated having considerably shorter horizontal wavelengths than that associated with the forcing near the surface. Nonlinear interactions can excite waves that are resonant with the background wind and static stability fields even when the primary surface forcing does not, and these waves can dominate the wave spectrum near cloud levels. A global map of Venus topographic slopes derived from Magellan altimetry data shows that slopes of magnitude comparable to or exceeding that used to force the model are ubiquitous over the surface. C1 AEROSP CORP,SPACE SCI LAB,LOS ANGELES,CA 90009. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. NASA,AMES RES CTR,DIV EARTH SYST SCI,MOFFETT FIELD,CA 94035. SPACE PHYS RES INST,SUNNYVALE,CA. UNIV CALIF LOS ANGELES,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. RP YOUNG, RE (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SCI,MAIL STOP 245-3,HAMPTON,VA 23665, USA. NR 26 TC 17 Z9 17 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 JUL 1 PY 1994 VL 51 IS 13 BP 1857 EP 1875 DI 10.1175/1520-0469(1994)051<1857:COFASG>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NX581 UT WOS:A1994NX58100006 ER PT J AU LEE, SC WHITE, S GRZESIK, JA AF LEE, SC WHITE, S GRZESIK, JA TI EFFECTIVE RADIATIVE PROPERTIES OF FIBROUS COMPOSITES CONTAINING SPHERICAL-PARTICLES SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA 28th Thermophysics Conference CY JUL 06-09, 1993 CL ORLANDO, FL SP AMER INST AERONAUT & ASTRONAUT ID SCATTERING; MEDIA AB The influence of spherical particles on the radiative properties of high-porosity fibrous composites is examined in this article. The radiative properties formulation is based on the independent scattering assumption, which utilizes the solution of Maxwell's equations for the interaction of electromagnetic waves with the respective types of particles. The extinction, absorption, and scattering coefficients, as well as the scattering phase function of the composites are formulated as the weighted average according to the fractional volume of the constituent particulates. The models are applied to predict the radiative properties of thermal insulation composites containing fibers and spheres that are made of zirconia and silica. Numerical results are presented to illustrate the influence of the respective types of particulates on the radiative properties of the composites. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP LEE, SC (reprint author), APPL SCI LAB INC,HACIENDA HTS,CA 91745, USA. NR 17 TC 7 Z9 8 U1 0 U2 4 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1994 VL 8 IS 3 BP 400 EP 405 DI 10.2514/3.556 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA NX844 UT WOS:A1994NX84400003 ER PT J AU CHAI, JC LEE, HS PATANKAR, SV AF CHAI, JC LEE, HS PATANKAR, SV TI FINITE-VOLUME METHOD FOR RADIATION HEAT-TRANSFER SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA 28th Thermophysics Conference CY JUL 06-09, 1993 CL ORLANDO, FL SP AMER INST AERONAUT & ASTRONAUT ID DISCRETE-ORDINATES METHOD; RECTANGULAR ENCLOSURES; ANISOTROPIC SCATTERING; COORDINATE SYSTEM; MEDIA; TRANSPORT; FLOWS AB A finite volume method (FVM) is presented in this article. This procedure can be used to model transparent, absorbing, emitting, and anisotropically scattering media. A procedure to capture collimated beam is also presented. The FVM is applied to six test problems, and the results compared favorably against other published results. The test problems include two- and three-dimensional enclosures with participating media, collimated incidence, and heat generation. The efficiency of the FVM procedure is also investigated using a three-dimensional test problem. C1 NASA,AMES RES CTR,DIV PROP SYST,MOFFETT FIELD,CA 94035. RP CHAI, JC (reprint author), UNIV MINNESOTA,DEPT MECH ENGN,MINNEAPOLIS,MN 55455, USA. RI Chai, John/A-3764-2010 NR 31 TC 258 Z9 269 U1 3 U2 28 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1994 VL 8 IS 3 BP 419 EP 425 DI 10.2514/3.559 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA NX844 UT WOS:A1994NX84400006 ER PT J AU TAYLOR, JC CARLSON, AB HASSAN, HA AF TAYLOR, JC CARLSON, AB HASSAN, HA TI MONTE-CARLO SIMULATION OF RADIATING REENTRY FLOWS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA 28th Thermophysics Conference CY JUL 06-09, 1993 CL ORLANDO, FL SP AMER INST AERONAUT & ASTRONAUT AB The direct simulation Monte Carlo method is applied to a radiating, hypersonic, axisymmetric now over a blunt body in the near continuum regime. The ability of the method to predict the flowfield radiation and the radiative heating is investigated for flow over the Project Fire II configuration at 11.36 km/s at an altitude of 76.42 km. Two methods that differ in the manner in which they treat ionization and estimate electronic excitation are employed. The calculated results are presented and compared with both experimental data and solutions where radiation effects were not included. Differences in the results are discussed. Both methods ignore self absorption and, as a result, overpredict measured radiative heating. C1 NASA,LANGLEY RES CTR,DIV SPACE SYST,AEROTHERMODYNAM BRANCH,HAMPTON,VA 23681. RP TAYLOR, JC (reprint author), N CAROLINA STATE UNIV,DEPT MECH & AEROSP ENGN,BOX 7910,RALEIGH,NC 27695, USA. NR 23 TC 11 Z9 11 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1994 VL 8 IS 3 BP 478 EP 485 DI 10.2514/3.568 PG 8 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA NX844 UT WOS:A1994NX84400015 ER PT J AU GUPTA, RN ZOBY, EV LEE, KP AF GUPTA, RN ZOBY, EV LEE, KP TI VISCOUS SHOCK-LAYER ANALYSIS OF 2-DIMENSIONAL AND AXISYMMETRICAL FLOWS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article; Proceedings Paper CT AIAA 28th Thermophysics Conference CY JUL 06-09, 1993 CL ORLANDO, FL SP AMER INST AERONAUT & ASTRONAUT ID SLENDER BODIES AB Results are obtained for cylindrical leading edges of proposed transatmospheric vehicles by employing a two-dimensional viscous shock-layer code for nonequilibrium gas flows. The accuracy and efficiency of the planar code is verified through detailed comparisons with other predictions. This study includes results for 6-deg half-angle bodies with nose radii ranging from 0.01 to 2.0 ft for both cylindrically blunted wedges and spherically blunted cones (included for comparison). Some results are presented as a ratio of the noncatalytic to the corresponding fully catalytic heating value to illustrate the maximum potential for a heating reduction in dissociated nonequilibrium flows. Generally, this ratio and the individual heating rates are smaller for cylindrically blunted wedges with small nose radii as compared to the spherically blunted cones (for the same nose radius). Therefore, a larger potential exists for heating reduction in cylindrically blunted as compared with the spherically blunted surfaces. However, the results presented at higher altitudes (where the slip effects become important) show that the spherically blunted nose gives lower stagnation-point heating due to stronger merged shock-layer effects as compared with a cylindrically blunted nose. C1 VIGYAN INC,HAMPTON,VA 23666. RP GUPTA, RN (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 18 TC 1 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1994 VL 8 IS 3 BP 494 EP 499 DI 10.2514/3.570 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA NX844 UT WOS:A1994NX84400017 ER PT J AU CHEN, KH KELECY, FJ PLETCHER, RH AF CHEN, KH KELECY, FJ PLETCHER, RH TI NUMERICAL AND EXPERIMENTAL-STUDY OF 3-DIMENSIONAL LIQUID SLOSHING FLOWS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID FLUID; SIMULATION; DYNAMICS AB A numerical and experimental study of three-dimensional liquid sloshing inside a partially filled spherical container is described. Solutions of the unsteady, incompressible Navier-Stokes equations are presented for two types of rotations: 1) initially-capped orbital motion, and 2) simple orbital rotation from rest to a prescribed steady-state angular velocity. The computed results from the second case are compared with experimental data from a rotating test rig fitted with two liquid-filled spherical tanks. C1 IOWA STATE UNIV SCI & TECHNOL,DEPT MECH ENGN,AMES,IA 50011. RP CHEN, KH (reprint author), UNIV TOLEDO,NASA,LANGLEY RES CTR,CLEVELAND,OH 44135, USA. NR 17 TC 2 Z9 6 U1 1 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1994 VL 8 IS 3 BP 507 EP 513 DI 10.2514/3.572 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA NX844 UT WOS:A1994NX84400019 ER PT J AU WANG, TS LUONG, V AF WANG, TS LUONG, V TI HOT-GAS-SIDE AND COOLANT-SIDE HEAT-TRANSFER IN LIQUID ROCKET ENGINE COMBUSTORS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB The objectives of this article are to develop a multidisciplinary, computational methodology to predict the hot-gas-side and coolant-side heat transfer in film cooling assisted, regeneratively cooled liquid rocket engine combustors, and to use it in parametric studies to recommend optimized design of the coolant channels for a developmental combustor. An integrated numerical model which incorporates computational fluid dynamics (CFD) for the hot-gas thermal environment, and thermal analysis for the liner and coolant channels, was developed. This integrated CFD/thermal model was validated by comparing predicted heat fluxes with those of hot-firing test and industrial design methods for a 40-k calorimeter thrust chamber and the Space Shuttle Main Engine main combustion chamber. Parametric studies were performed for the advanced main combustion chamber to find a strategy for a proposed coolant channel design. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,THERMAL ANAL LAB,HUNTSVILLE,AL 35812. RP WANG, TS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,COMP FLUID DYNAM BRANCH,HUNTSVILLE,AL 35812, USA. NR 19 TC 19 Z9 20 U1 0 U2 10 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1994 VL 8 IS 3 BP 524 EP 530 DI 10.2514/3.574 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA NX844 UT WOS:A1994NX84400021 ER PT J AU WANG, TS CHYU, MK AF WANG, TS CHYU, MK TI HEAT CONVECTION IN A 180-DEG TURNING DUCT WITH DIFFERENT TURN CONFIGURATIONS SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article ID SMOOTH RECTANGULAR CHANNELS; FLOW AB The numerical results for secondary flow patterns and heat transfer distribution in a two-pass, square duct with a 180-deg sharp turn are presented to examine the effects of three different turning configurations: 1) straight-corner turn, 2) rounded-corner turn, and 3) circular turn. The simulation employs a nonstaggered grid, pressure-based, finite difference method and solves for three-dimensional transport equations in curvilinear coordinates. Modeling of turbulence uses an extended version of k-epsilon model. The computed results reveal that secondary flow in the post-turn region displays combined features of a bend-induced, Dean-type circulation and a form-induced separation behind the partition wall. The detailed flow structure as well as its effect on the local heat transfer varies significantly with different turn configurations. At the turn, the straight-corner case has the strongest turn-induced heat transfer enhancement, while the circular turn has the weakest. In the post-turn region heat transfer with circular turn surpasses those of the other two configurations by almost the same difference in the turning region. Average heat transfer results from the present numerical modeling agree favorably with experimental data. C1 CARNEGIE MELLON UNIV,DEPT MECH ENGN,PITTSBURGH,PA 15213. RP WANG, TS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,COMP FLUID DYNAM BRANCH,HUNTSVILLE,AL 35812, USA. NR 21 TC 35 Z9 35 U1 1 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1994 VL 8 IS 3 BP 595 EP 601 DI 10.2514/3.583 PG 7 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA NX844 UT WOS:A1994NX84400030 ER PT J AU SIEGEL, R AF SIEGEL, R TI REFRACTIVE-INDEX EFFECTS ON LOCAL RADIATIVE EMISSION FROM A RECTANGULAR SEMITRANSPARENT SOLID SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Note ID BOUNDARY HEAT FLUXES RP SIEGEL, R (reprint author), NASA,LEWIS RES CTR,LEWIS RES ACAD,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 6 TC 5 Z9 5 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD JUL-SEP PY 1994 VL 8 IS 3 BP 625 EP 628 DI 10.2514/3.589 PG 4 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA NX844 UT WOS:A1994NX84400036 ER PT J AU KHOSARI, MM DIMOFTE, F AF KHOSARI, MM DIMOFTE, F TI ANGULAR-COMPLIANT HYDRODYNAMIC BEARING PERFORMANCE UNDER DYNAMIC LOADS - DISCUSSION SO JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME LA English DT Discussion C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP KHOSARI, MM (reprint author), UNIV PITTSBURGH,DEPT MECH ENGN,PITTSBURGH,PA 15261, USA. NR 7 TC 0 Z9 0 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4787 J9 J TRIBOL-T ASME JI J. Tribol.-Trans. ASME PD JUL PY 1994 VL 116 IS 3 BP 661 EP 661 PG 1 WC Engineering, Mechanical SC Engineering GA NZ739 UT WOS:A1994NZ73900035 ER PT J AU BUFFUM, DH FLEETER, S AF BUFFUM, DH FLEETER, S TI EFFECT OF WIND-TUNNEL ACOUSTIC MODES ON LINEAR OSCILLATING CASCADE AERODYNAMICS SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article; Proceedings Paper CT 38th International Gas Turbine and Aeroengine Congress and Exposition CY MAY 24-27, 1993 CL CINCINNATI, OH SP INT GAS TURBINE INST AB The aerodynamics of a biconvex airfoil cascade oscillating in torsion is investigated using the unsteady aerodynamic influence coefficient technique. For subsonic flow and reduced frequencies as large as 0.9, airfoil surface unsteady pressures resulting from oscillation of one of the airfoils are measured using flush-mounted high-frequency-response pressure transducers. The influence coefficient data are examined in detail and then used to predict the unsteady aerodynamics of a cascade oscillating at various interblade phase angles. These results are correlated with experimental data obtained in the traveling-wave mode of oscillation and linearized analysis predictions. It is found that the unsteady pressure disturbances created by an oscillating airfoil excite wind tunnel acoustic modes, which have detrimental effects on the experimental results. Acoustic treatment is proposed to rectify this problem. C1 PURDUE UNIV,SCH MECH ENGN,CTR THERMAL SCI & PROP,W LAFAYETTE,IN 47907. RP BUFFUM, DH (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 14 TC 5 Z9 6 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD JUL PY 1994 VL 116 IS 3 BP 513 EP 524 DI 10.1115/1.2929440 PG 12 WC Engineering, Mechanical SC Engineering GA NZ009 UT WOS:A1994NZ00900020 ER PT J AU STALDER, RE BOUMSELLEK, S VANZANDT, TR KENNY, TW HECHT, MH GRUNTHANER, FE AF STALDER, RE BOUMSELLEK, S VANZANDT, TR KENNY, TW HECHT, MH GRUNTHANER, FE TI MICROMACHINED ARRAY OF ELECTROSTATIC ENERGY ANALYZERS FOR CHARGED-PARTICLES SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article AB The design, fabrication techniques, and first test results of a new type of micromachined energy analyzer for charged particles are presented. The novel design is based on a Bessel Box straight-line geometry with focusing in one dimension. The problem of small acceptance area due to the drastically reduced overall dimensions is accounted for by the use of a parallel array of small analyzers simultaneously. We describe the fabrication of a proof-of-concept micromachined Bessel Box array by means of anisotropic wet etching of [110] silicon, and we present ray-tracing simulations for a simple geometry. Finally, we show some test results of Auger electrons and discuss possible applications of generic small charged particle analyzers. RP STALDER, RE (reprint author), JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 9 TC 10 Z9 10 U1 0 U2 1 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 JUL-AUG PY 1994 VL 12 IS 4 BP 2554 EP 2558 DI 10.1116/1.579056 PN 2 PG 5 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA NZ032 UT WOS:A1994NZ03200137 ER PT J AU RAMAN, G RICE, EJ AF RAMAN, G RICE, EJ TI DEVELOPMENT OF PHASED TWIN FLIP-FLOP JETS SO JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME LA English DT Article AB The flip-flop nozzle is a device that can produce an oscillating jet flow without any moving parts. There is now a renewed interest in such nozzles due to their potential for use as excitation devices in practical applications. An experiment aimed at developing twin flip-flop jets that operate at prescribed frequencies and phase differences was performed. The phasing was achieved using two different nozzle interconnection schemes. In one configuration the two jets flapped in-phase and in another they flapped out-of-phase with respect to each other. In either configuration the frequencies of oscillation of both jets were equal. When one of the jets was run at a constant high velocity and the velocity of the second jet was increased gradually, the higher velocity jet determined the frequency of oscillation of both jets. The two flip-flop jet configurations described in this paper could be used to excite a primary jet flow in either an anti-symmetric (sinuous) or a symmetric (varicose) mode. RP RAMAN, G (reprint author), NYMA INC,NASA,LEWIS RES CTR GRP,EXPTL FLUID DYNAM SECT,BROOKPARK,OH 44142, USA. NR 0 TC 6 Z9 6 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 1048-9002 J9 J VIB ACOUST JI J. Vib. Acoust.-Trans. ASME PD JUL PY 1994 VL 116 IS 3 BP 263 EP 268 DI 10.1115/1.2930423 PG 6 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA NZ394 UT WOS:A1994NZ39400003 ER PT J AU PINELLI, TE AF PINELLI, TE TI SPECIAL-LIBRARIES - INCREASING THE INFORMATION EDGE - GRIFFITHS,JM, KING,DW SO LIBRARY QUARTERLY LA English DT Book Review RP PINELLI, TE (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0024-2519 J9 LIBR QUART JI Libr. Q. PD JUL PY 1994 VL 64 IS 3 BP 344 EP 345 PG 2 WC Information Science & Library Science SC Information Science & Library Science GA NY160 UT WOS:A1994NY16000012 ER PT J AU SLINEY, HE DELLACORTE, C AF SLINEY, HE DELLACORTE, C TI THE FRICTION AND WEAR OF CERAMIC-CERAMIC AND CERAMIC-METAL COMBINATIONS IN SLIDING CONTACT SO LUBRICATION ENGINEERING LA English DT Article DE TRIBOLOGY OF CERAMICS AB The tribological characteristics of ceramics sliding on ceramics are compared to those of ceramics sliding on a nickel-based turbine alloy. The friction and wear of oxide ceramics and silicon-based ceramics in air at temperatures from room ambient to 900-degrees-C (in a few cases to 1200-degrees-C) were measured for a hemispherically-tipped pin on a flat sliding contact geometry. In general, especially at high temperature, friction and wear were lower for ceramic/metal combinations than for ceramic/ceramic combinations. The better tribological performance for ceramic/metal combinations is attributed primarily to the lubricious nature of the oxidized surface of the metal. RP SLINEY, HE (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 12 TC 21 Z9 24 U1 0 U2 1 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0024-7154 J9 LUBR ENG JI Lubric. Eng. PD JUL PY 1994 VL 50 IS 7 BP 571 EP 576 PG 6 WC Engineering, Mechanical SC Engineering GA NY836 UT WOS:A1994NY83600010 ER PT J AU MULLIN, KD HANSEN, LJ HOGGARD, W JEFFERSON, TA AF MULLIN, KD HANSEN, LJ HOGGARD, W JEFFERSON, TA TI 1ST SIGHTINGS OF MELON-HEADED WHALES (PEPONOCEPHALA-ELECTRA) IN THE GULF-OF-MEXICO SO MARINE MAMMAL SCIENCE LA English DT Note C1 TEXAS A&M UNIV,DEPT WILDLIFE & FISHERIES SCI,MARINE MAMMAL RES PROGRAM,COLLEGE STN,TX 77843. NOAA,NATL MARINE FISHERIES SERV,SE FISHERIES SCI CTR,MIAMI,FL 33149. RP MULLIN, KD (reprint author), NOAA,NATL MARINE FISHERIES SERV,SE FISHERIES SCI CTR,POB DRAWER 1207,PASCAGOULA,MS 39568, USA. NR 18 TC 6 Z9 8 U1 1 U2 2 PU SOC MARINE MAMMALOGY PI LAWRENCE PA 1041 NEW HAMPSHIRE ST, LAWRENCE, KS 66044 SN 0824-0469 J9 MAR MAMMAL SCI JI Mar. Mamm. Sci. PD JUL PY 1994 VL 10 IS 3 BP 342 EP 348 DI 10.1111/j.1748-7692.1994.tb00488.x PG 7 WC Marine & Freshwater Biology; Zoology SC Marine & Freshwater Biology; Zoology GA PE111 UT WOS:A1994PE11100008 ER PT J AU HENNINGSEN, T SINGH, NB HOPKINS, RH MAZELSKY, R HOPKINS, FK FRAZIER, DO SINGH, OP AF HENNINGSEN, T SINGH, NB HOPKINS, RH MAZELSKY, R HOPKINS, FK FRAZIER, DO SINGH, OP TI GROWTH OF BINARY ORGANIC NLO CRYSTALS - M-NA P-NA AND M-NA CNA SYSTEMS SO MATERIALS LETTERS LA English DT Article AB Experiments were carried out to grow 3-nitroaniline (m.NA) crystals doped with 4-nitroaniline (p.NA) and 2-chloro 4-nitroaniline (CNA). The measured undercooling for m.NA, p.NA, and CNA were 0.21, 0.23 and 0.35 t(m) K respectively, where t(m) represents the melting temperature of the pure component. Because of the crystals' large heat of fusion and large undercooling, it was not possible to grow good quality crystals with low thermal gradients. In the conventional two-zone Bridgman furnace, the temperature of the hot zone had to be raised above the decomposition temperature of CNA, p.NA and m.NA to achieve the desired thermal gradient. To avoid decomposition, an unconventional Bridgman furnace was used. Two immiscible liquids, silicone oil and ethylene glycol, were used to build a special two-zone Bridgman furnace. A temperature gradient of 18 K/cm was achieved without exceeding the decomposition temperature of the crystal. The binary crystals, m.NA-p.NA and m.NA-CNA, were grown in centimeter sizes in this furnace. X-ray and optical characterization showed good optical quality. C1 WRIGHT LAB,MAT DIRECTORATE,WRIGHT PATTERSON AFB,OH 45433. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. KN GOVT POST GRAD COLL,DEPT CHEM,GYANPUR,UTTAR PRADESH,INDIA. RP HENNINGSEN, T (reprint author), WESTINGHOUSE ELECT CORP,CTR SCI & TECHNOL,PITTSBURGH,PA 15235, USA. NR 5 TC 6 Z9 6 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-577X J9 MATER LETT JI Mater. Lett. PD JUL PY 1994 VL 20 IS 3-4 BP 203 EP 209 DI 10.1016/0167-577X(94)90088-4 PG 7 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA PB458 UT WOS:A1994PB45800022 ER PT J AU HUSTON, RL MAVRIPLIS, D OSWALD, FB LIU, YS AF HUSTON, RL MAVRIPLIS, D OSWALD, FB LIU, YS TI A BASIS FOR SOLID MODELING OF GEAR TEETH WITH APPLICATION IN DESIGN AND MANUFACTURE SO MECHANISM AND MACHINE THEORY LA English DT Article AB This paper discusses a new approach to modeling gear tooth surfaces. A computer graphics solid modeling procedure is used to simulate the tooth fabrication processes. This procedure is based on the principles of differential geometry that pertain to envelopes of curves and surfaces. The procedure is illustrated with the modeling of spur, helical, bevel, spiral bevel and hypoid gear teeth. Applications in design and manufacturing are discussed. Extensions to nonstandard tooth forms, to cams, and to rolling element bearings are proposed. C1 EDS,CINCINNATI,OH 45246. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. FENG CHIA UNIV,TAICHUNG,TAIWAN. RP HUSTON, RL (reprint author), UNIV CINCINNATI,CINCINNATI,OH 45221, USA. NR 19 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-114X J9 MECH MACH THEORY JI Mech. Mach. Theory PD JUL PY 1994 VL 29 IS 5 BP 713 EP 723 DI 10.1016/0094-114X(94)90113-9 PG 11 WC Engineering, Mechanical SC Engineering GA NU211 UT WOS:A1994NU21100006 ER PT J AU MACKAY, RA DRAPER, SL RITTER, AM SIEMERS, PA AF MACKAY, RA DRAPER, SL RITTER, AM SIEMERS, PA TI A COMPARISON OF THE MECHANICAL-PROPERTIES AND MICROSTRUCTURES OF INTERMETALLIC MATRIX COMPOSITES FABRICATED BY 2 DIFFERENT METHODS SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID SIC FIBERS; WEIBULL DISTRIBUTION; STRENGTH; SIC/TI-24AL-11NB; TEMPERATURE AB The tensile properties of SCS-6 SiC fiber-reinforced Ti-24Al-11Nb (at. pct) have been measured over the past several years by a number of investigators. These composites have been fabricated by different techniques and tend to exhibit a large amount of scatter in the longitudinal tensile properties. To date, it is not known if one optimized fabrication method provides composites with improved mechanical properties over those produced by other optimized methods, since carefully controlled experiments have not been performed to determine this. Thus, the purpose of the present study was to compare the longitudinal tensile strengths of SCS-6 SiC/Ti-24Al-11Nb composites that had been fabricated by the powder-cloth method and the low-pressure plasma spray (LPPS) method. In this study, the same lots of matrix powder and reinforcing fiber were used for fabricating the composites. It was determined that the powder-cloth and plasma spray methods produced composites having very similar tensile properties. Both fabrication methods induced damage in a small percentage of fibers, which manifested itself in the form of bimodal Weibull distributions of extracted fiber strengths. It appeared that the particular lot of SCS-6 fiber used in fabricating both types of composites was more susceptible to fabrication damage than those used in previous studies. This article also shows the dramatic effect that different handling and testing techniques can have on measured fiber strengths. C1 GE CO,CORP RES & DEV,SCHENECTADY,NY 12345. RP MACKAY, RA (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 24 TC 20 Z9 20 U1 0 U2 1 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD JUL PY 1994 VL 25 IS 7 BP 1443 EP 1455 DI 10.1007/BF02665477 PG 13 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA NU215 UT WOS:A1994NU21500011 ER PT J AU ASPHAUG, E AF ASPHAUG, E TI LARGE EJECTA FRAGMENTS FROM ASTEROIDS SO METEORITICS LA English DT Meeting Abstract ID METEORITES; IMPACT C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 10 TC 2 Z9 2 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 440 EP 441 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400010 ER PT J AU BISHOP, J PIETERS, C MUSTARD, J PRATT, S HIROI, T AF BISHOP, J PIETERS, C MUSTARD, J PRATT, S HIROI, T TI SPECTRAL ANALYSES OF ALH-84001, A METEORITE FROM MARS SO METEORITICS LA English DT Meeting Abstract C1 BROWN UNIV,PROVIDENCE,RI 02912. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 2 TC 7 Z9 7 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 444 EP 445 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400018 ER PT J AU BROWNING, LB MCSWEEN, HY ZOLENSKY, M AF BROWNING, LB MCSWEEN, HY ZOLENSKY, M TI FORMATION OF THIN SULFIDE RINDS ON THE CM PARENT BODY SO METEORITICS LA English DT Meeting Abstract ID DISSOLUTION KINETICS; CHONDRITES; MURCHISON C1 UNIV TENNESSEE,DEPT GEOL SCI,KNOXVILLE,TN 37996. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 9 TC 1 Z9 1 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 450 EP 450 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400030 ER PT J AU CHAPMAN, CR KLAASEN, K BELTON, MJS VEVERKA, J AF CHAPMAN, CR KLAASEN, K BELTON, MJS VEVERKA, J TI ASTEROID 243 IDA AND ITS SATELLITE SO METEORITICS LA English DT Meeting Abstract C1 PLANETARY SCI INST,TUCSON,AZ 85705. NATL OPT ASTRON OBSERV,TUCSON,AZ 85719. JET PROP LAB,PASADENA,CA 91109. CORNELL UNIV,ITHACA,NY 14853. NR 5 TC 1 Z9 1 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 455 EP 455 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400040 ER PT J AU CONNOLLY, HC HEWINS, RH ATRE, N LOFGREN, GE AF CONNOLLY, HC HEWINS, RH ATRE, N LOFGREN, GE TI COMPOUND CHONDRULES - AN EXPERIMENTAL INVESTIGATION SO METEORITICS LA English DT Meeting Abstract C1 RUTGERS STATE UNIV,DEPT GEOL SCI,NEW BRUNSWICK,NJ 08903. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 6 TC 10 Z9 10 U1 0 U2 2 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 458 EP 458 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400046 ER PT J AU IVANOV, AV ZOLENSKY, ME BRANDSTATTER, F KURAT, G KONONKOVA, NN AF IVANOV, AV ZOLENSKY, ME BRANDSTATTER, F KURAT, G KONONKOVA, NN TI A PHYLLOSILICATE-SULFIDE VEIN IN KAIDUN SO METEORITICS LA English DT Meeting Abstract C1 VERNADSKY GEOCHEM & ANALYT CHEM INST,MOSCOW 117975,RUSSIA. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NAT HIST MUSEUM,A-1014 VIENNA,AUSTRIA. NR 4 TC 3 Z9 4 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 477 EP 477 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400082 ER PT J AU KELLER, LP THOMAS, KL MCKAY, DS AF KELLER, LP THOMAS, KL MCKAY, DS TI THE NATURE OF CARBON-BEARING PHASES IN HYDRATED INTERPLANETARY DUST PARTICLES SO METEORITICS LA English DT Meeting Abstract C1 MVA INC,NORCROSS,GA 30093. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 2 TC 12 Z9 13 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 480 EP 481 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400089 ER PT J AU KELLER, LP MCKAY, DS AF KELLER, LP MCKAY, DS TI THE CONTRIBUTION OF VAPOR-DEPOSITION TO AMORPHOUS RIMS ON LUNAR SOIL GRAINS SO METEORITICS LA English DT Meeting Abstract C1 MVA INC,NORCROSS,GA 30093. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 2 TC 12 Z9 13 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 480 EP 480 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400088 ER PT J AU KERRIDGE, JF MCSWEEN, HYUP BUNCH, TE AF KERRIDGE, JF MCSWEEN, HYUP BUNCH, TE TI PETROLOGIC EVOLUTION OF CM CHONDRITES - THE DIFFICULTY OF DISCRIMINATING BETWEEN NEBULAR AND PARENT-BODY EFFECTS SO METEORITICS LA English DT Meeting Abstract C1 UNIV CALIF SAN DIEGO,DEPT CHEM,LA JOLLA,CA 92093. UNIV TENNESSEE,DEPT GEOL SCI,KNOXVILLE,TN 37996. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 4 TC 2 Z9 2 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 481 EP 481 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400090 ER PT J AU LINDSTROM, MM AF LINDSTROM, MM TI WHAT WOULD WE MISS IF WE CHARACTERIZED THE MOON AND MARS WITH JUST PLANETARY METEORITES, REMOTE MAPPING, AND ROBOTIC LANDERS SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 491 EP 491 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400111 ER PT J AU MCKAY, DS ALLEN, CC AF MCKAY, DS ALLEN, CC TI EXPERIMENTAL SPACE WEATHERING OF REGOLITH MATERIAL SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. NR 4 TC 1 Z9 1 U1 1 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 500 EP 500 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400129 ER PT J AU MIKOUCHI, T MCKAY, G MIYAMOTO, M TAKEDA, H AF MIKOUCHI, T MCKAY, G MIYAMOTO, M TAKEDA, H TI DIFFUSIVE MODIFICATION OF PRIMARY ZONING IN OLIVINE CORES IN ANGRITE LEW-87051 SO METEORITICS LA English DT Meeting Abstract C1 UNIV TOKYO,INST MINERAL,TOKYO 113,JAPAN. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 1 Z9 1 U1 1 U2 4 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 503 EP 504 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400136 ER PT J AU MITTLEFEHLDT, DW LINDSTROM, MM AF MITTLEFEHLDT, DW LINDSTROM, MM TI GEOCHEMCIAL EVIDENCE FOR MIXING OF 3 COMPONENTS IN MARTIAN ORTHOPYROXENITE ALH84001 SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. NR 0 TC 3 Z9 3 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 504 EP 504 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400137 ER PT J AU NYQUIST, L LINDSTROM, D WIESMANN, H MARTINEZ, R BANSAL, B MITTLEFEHLDT, D SHIH, CY WENTWORTH, S AF NYQUIST, L LINDSTROM, D WIESMANN, H MARTINEZ, R BANSAL, B MITTLEFEHLDT, D SHIH, CY WENTWORTH, S TI MN-CR ISOTOPIC SYSTEMATICS OF INDIVIDUAL CHAINPUR CHONDRULES SO METEORITICS LA English DT Meeting Abstract C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77258. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 2 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 512 EP 513 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400152 ER PT J AU ROMANEK, CS MITTLEFEHLDT, DW GIBSON, EK SOCKI, RA AF ROMANEK, CS MITTLEFEHLDT, DW GIBSON, EK SOCKI, RA TI MARTIAN CARBONATES IN ALH 84001 - TEXTURAL, ELEMENTAL, AND STABLE ISOTOPIC COMPOSITIONAL EVIDENCE ON THEIR FORMATION SO METEORITICS LA English DT Meeting Abstract C1 LOCKHEAD ENGN & SCI CO,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH,HOUSTON,TX 77058. NR 0 TC 6 Z9 6 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 JUL PY 1994 VL 29 IS 4 BP 523 EP 523 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400172 ER PT J AU ROWAN, LR AF ROWAN, LR TI SHOCK RECOVERY ANALOGS AND THE ORIGIN OF MESOSIDERITES SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 6 TC 0 Z9 0 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 524 EP 524 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400174 ER PT J AU STRAIT, MM BASU, A MCKAY, DS ROBINSON, R AF STRAIT, MM BASU, A MCKAY, DS ROBINSON, R TI MEASURING GLASS ABUNDANCES IN LUNAR AGGLUTINATES SO METEORITICS LA English DT Meeting Abstract C1 ALMA COLL,ALMA,MI 48801. INDIANA UNIV,BLOOMINGTON,IN 47405. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 6 TC 1 Z9 1 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 537 EP 538 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400204 ER PT J AU WEISBERG, MK PRINZ, M ZOLENSKY, ME IVANOV, AV AF WEISBERG, MK PRINZ, M ZOLENSKY, ME IVANOV, AV TI CARBONATES IN THE KAIDUN CHONDRITE SO METEORITICS LA English DT Meeting Abstract ID CI C1 AMER MUSEUM NAT HIST,NEW YORK,NY 10024. VA VERNADSKY GEOCHEM & ANALYT CHEM INST,MOSCOW 117975,RUSSIA. AMER MUSEUM NAT HIST,NEW YORK,NY 10024. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 6 TC 10 Z9 11 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 549 EP 550 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400227 ER PT J AU ZOLENSKY, ME BROWNING, LB AF ZOLENSKY, ME BROWNING, LB TI CM CHONDRITES EXHIBIT THE COMPLETE PETROLOGIC RANGE FROM TYPE-2 TO TYPE-1 SO METEORITICS LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV TENNESSEE,KNOXVILLE,TN 37996. NR 3 TC 12 Z9 12 U1 0 U2 0 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD JUL PY 1994 VL 29 IS 4 BP 556 EP 556 PG 1 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NW884 UT WOS:A1994NW88400240 ER PT J AU DUH, JC AF DUH, JC TI MARANGONI-BENARD CONVECTION IN A LOW-ASPECT-RATIO LIQUID LAYER SO MICROGRAVITY SCIENCE AND TECHNOLOGY LA English DT Article AB This paper presents the results of a study on the variation of the critical Marangoni number (Ma(c)) for the onset of Benard convection in a finite liquid layer bounded horizontally as well as from below. A direct-numerical-simulation procedure is devised to determine the Ma, for aspect ratios (Ar) ranging from 0.8 to 10. The results predict a strong increase of Ma(c). as Ar decreases to below 2. A dip of Ma, occurs between Ar = 1.45 and 1.3, which is accompanied by a pattern transition from a two-cell convection to a unicellular flow. For Ar above 4, the calculated Ma(c). shows little change and asymptotically approach a value of 116.15, with Biot number (Bi) equal to 1. RP DUH, JC (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,MS 500-327,CLEVELAND,OH 44135, USA. NR 13 TC 4 Z9 4 U1 0 U2 0 PU CARL HANSER VERLAG PI MUNICH PA KOLBERGERSTRASSE 22, POSTFACH 860420, W-8163 MUNICH, GERMANY SN 0938-0108 J9 MICROGRAVITY SCI TEC JI Microgravity Sci. Technol. PD JUL PY 1994 VL 7 IS 2 BP 98 EP 102 PG 5 WC Engineering, Aerospace; Thermodynamics; Mechanics SC Engineering; Thermodynamics; Mechanics GA PB218 UT WOS:A1994PB21800005 ER PT J AU GRAYSON, G SACKSTEDER, KR FERKUL, PV TIEN, JS AF GRAYSON, G SACKSTEDER, KR FERKUL, PV TIEN, JS TI FLAME SPREADING OVER A THIN SOLID IN LOW-SPEED CONCURRENT FLOW - DROP TOWER EXPERIMENTAL RESULTS AND COMPARISON WITH THEORY SO MICROGRAVITY SCIENCE AND TECHNOLOGY LA English DT Article ID FUEL; MICROGRAVITY AB Flame spread over thin paper samples in low-speed concurrent flow is experimentally investigated in a 5.18 s drop tower. In the experiment, the oxygen. molar percentage is varied from 30 % down to the flame extinction limits and the forced flow velocity from 5.29 cm Is down to the quenching limits. Motion pictures are taken to observe flame shape, color, size, and spread rates. These quantities are compared with a theoretical model describing concurrent flame spread over thin solids in low-speed flows. The paper also discusses the similarity and difference between concurrent-flow and opposed-flow flame spread in microgravity and between low-speed and high-speed concurrent-flow flame spread. Finally the limitations of using a drop tower for flame spread research is assessed. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP GRAYSON, G (reprint author), CASE WESTERN RESERVE UNIV,415 GLENNAN BLDG,CLEVELAND,OH 44106, USA. NR 19 TC 33 Z9 34 U1 0 U2 2 PU CARL HANSER VERLAG PI MUNICH PA KOLBERGERSTRASSE 22, POSTFACH 860420, W-8163 MUNICH, GERMANY SN 0938-0108 J9 MICROGRAVITY SCI TEC JI Microgravity Sci. Technol. PD JUL PY 1994 VL 7 IS 2 BP 187 EP 195 PG 9 WC Engineering, Aerospace; Thermodynamics; Mechanics SC Engineering; Thermodynamics; Mechanics GA PB218 UT WOS:A1994PB21800022 ER PT J AU LONG, MM DELUCAS, LJ SMITH, C CARSON, M MOORE, K HARRINGTON, MD PILLION, DJ BISHOP, SP ROSENBLUM, WM NAUMANN, RJ CHAIT, A PRAHL, J BUGG, CE AF LONG, MM DELUCAS, LJ SMITH, C CARSON, M MOORE, K HARRINGTON, MD PILLION, DJ BISHOP, SP ROSENBLUM, WM NAUMANN, RJ CHAIT, A PRAHL, J BUGG, CE TI PROTEIN CRYSTAL-GROWTH IN MICROGRAVITY - TEMPERATURE-INDUCED LARGE-SCALE CRYSTALLIZATION OF INSULIN SO MICROGRAVITY SCIENCE AND TECHNOLOGY LA English DT Article ID PHOSPHORYLATION AB One of the major stumbling blocks that prevents rapid structure determination using x-ray crystallography is macromolecular crystal growth. There are many examples where crystallization takes longer than structure determination. In some cases, it is impossible to grow useful crystals on earth. Recent experiments conducted in conjunction with NASA on various Space Shuttle missions have demonstrated that protein crystals often grow larger and display better internal molecular order than their earth-grown counterparts. This paper reports results from three Shuttle flights using the Protein Crystallization Facility (PCF). The PCF hardware produced large, high-quality insulin crystals by using a temperature change as the sole means to affect protein solubility and thus, crystallization. The facility consists of cylinders/containers with volumes of 500, 200, 100, and 50 ml. Data from the three Shuttle flights demonstrated that larger, higher resolution crystals (as evidenced by x-ray diffraction data) were obtained from the microgravity experiments when compared to earth-grown crystals. C1 UNIV ALABAMA,DIV MOLEC & CELLULAR PATHOL,BIRMINGHAM,AL 35294. UNIV ALABAMA,DEPT PHARMACOL,BIRMINGHAM,AL 35294. UNIV ALABAMA,DEPT PHYSIOL OPT,BIRMINGHAM,AL 35294. CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP LONG, MM (reprint author), UNIV ALABAMA,CTR MACROMOLEC CRYSTALLOG,262 BASIC HLTH SCI BLDG,THT79,BIRMINGHAM,AL 35294, USA. NR 24 TC 17 Z9 17 U1 2 U2 4 PU CARL HANSER VERLAG PI MUNICH PA KOLBERGERSTRASSE 22, POSTFACH 860420, W-8163 MUNICH, GERMANY SN 0938-0108 J9 MICROGRAVITY SCI TEC JI Microgravity Sci. Technol. PD JUL PY 1994 VL 7 IS 2 BP 196 EP 202 PG 7 WC Engineering, Aerospace; Thermodynamics; Mechanics SC Engineering; Thermodynamics; Mechanics GA PB218 UT WOS:A1994PB21800023 PM 11541852 ER PT J AU WU, TK HUANG, J AF WU, TK HUANG, J TI LOW-COST ANTENNAS FOR DIRECT BROADCAST SATELLITE RADIO SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE DIRECT BROADCAST SATELLITE RADIO; LOW-COST ANTENNAS; CIRCULAR POLARIZATION; MOBILE TERMINAL AB Two omnidirectional and circularly polarized low-gain antennas (the crossed drooping dipole and the TM21-mode circular patch antenna) are developed for direct broadcast satellite radio (DBSR) outdoor mobile terminal applications. Two medium-gain circularly polarized microstrip patch arrays [one uses the conventional circular polarization (CP) feed and the other uses the sequentially arranged CP feed techniques] are also developed to provide at least 12-dBic peak gain for DBSR indoor fixed terminal applications. The sequentially arranged CP fed array has a better CP performance over a broader bandwidth than the conventionally fed array. All the antennas are small in size/mass and inexpensive in fabrication cost. The patch antennas also have a low profile. (C) 1994 John Wiley & Sons, Inc. RP WU, TK (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 1 Z9 1 U1 2 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 JUL PY 1994 VL 7 IS 10 BP 440 EP 444 DI 10.1002/mop.4650071005 PG 5 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA NU031 UT WOS:A1994NU03100004 ER PT J AU FRANCISCO, JS AF FRANCISCO, JS TI AN AB-INITIO CALCULATION OF THE ENERGETICS FOR THE FO+HCL-]HOF+CL REACTION SO MOLECULAR PHYSICS LA English DT Note ID KINETICS; HCL; OH AB Reaction energetics have been calculated using ab initio methods for the reaction HO + HCl --> H2O + Cl and FO + HCl --> HOF + Cl. At the QCISD(T)/6-311 ++ G(3df, 3pd) level of theory, the heats of reaction are estimated as -61.5 and 12.1 kJ mol-1 respectively. The activation barrier for HO + HCl reaction at 298 K is estimated as 4.6 kJ mol-1. This result overestimates the experimental results by 2.5 kJ mol-1. The FO + HCl reaction is predicted to have an activation barrier of 54-8 +/- 8 kJ mol-1. C1 PURDUE UNIV,DEPT EARTH & ATMOSPHER SCI,W LAFAYETTE,IN 47907. PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. RP FRANCISCO, JS (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 12 TC 2 Z9 2 U1 0 U2 0 PU TAYLOR & FRANCIS LTD PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0026-8976 J9 MOL PHYS JI Mol. Phys. PD JUL PY 1994 VL 82 IS 4 BP 831 EP 833 DI 10.1080/00268979400100594 PG 3 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NZ038 UT WOS:A1994NZ03800015 ER PT J AU LIN, SJ CHAO, WC SUD, YC WALKER, GK AF LIN, SJ CHAO, WC SUD, YC WALKER, GK TI A CLASS OF THE VANLEER-TYPE TRANSPORT SCHEMES AND ITS APPLICATION TO THE MOISTURE TRANSPORT IN A GENERAL-CIRCULATION MODEL SO MONTHLY WEATHER REVIEW LA English DT Article ID CONSERVATIVE DIFFERENCE SCHEME; PARABOLIC METHOD PPM; CUMULUS PARAMETERIZATION; BIOSPHERE MODEL; CLIMATE; SENSITIVITY; ABSORPTION; SIMULATION; RADIATION; ADVECTION AB A generalized form of the second-order van Leer transport scheme is derived. Several constraints to the implied subgrid linear distribution are discussed. A very simple positive-definite scheme can be derived directly from the generalized form. A monotonic version of the scheme is applied to the Goddard Laboratory for Atmospheres (GLA) general circulation model (GCM) for the moisture transport calculations, replacing the original fourth-order center-differencing scheme. Comparisons with the original scheme are made in idealized tests as well as in a summer climate simulation using the full GLA GCM. A distinct advantage of the monotonic transport scheme is its ability to transport sharp gradients without producing spurious oscillations and unphysical negative mixing ratio. Within the context of low-resolution climate simulations, the aforementioned characteristics are demonstrated to be very beneficial in regions where cumulus convection is active. The model-produced precipitation pattern using the new transport scheme is more coherently organized both in time and in space, and correlates better with observations. The side effect of the filling algorithm used in conjunction with the original scheme is also discussed, in the context of idealized tests. The major weakness of the proposed transport scheme with a local monotonic constraint is its substantial implicit diffusion at low resolution. Alternative constraints are discussed to counter this problem. RP NASA, GODDARD SPACE FLIGHT CTR, GEN SCI CORP, ATMOSPHERES LAB, CODE 9103, GREENBELT, MD 20771 USA. NR 46 TC 59 Z9 60 U1 0 U2 5 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0027-0644 EI 1520-0493 J9 MON WEATHER REV JI Mon. Weather Rev. PD JUL PY 1994 VL 122 IS 7 BP 1575 EP 1593 DI 10.1175/1520-0493(1994)122<1575:ACOTVL>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NU466 UT WOS:A1994NU46600011 ER PT J AU ABURDENE, MF DORBAND, JE AF ABURDENE, MF DORBAND, JE TI UNIFICATION OF LEGENDRE, LAGUERRE, HERMITE, AND BINOMIAL DISCRETE-TRANSFORMS USING PASCAL MATRIX SO MULTIDIMENSIONAL SYSTEMS AND SIGNAL PROCESSING LA English DT Article AB Pascal's matrix plays an important role in the computation of the discrete Legendre, Laguerre, Hermite, and binomial transforms. In particular, Pascal's matrix helps to unify the formulation of these orthogonal transforms and demonstrate the similarity of the computation of the transform matrices. It also allows the identification of the identical computations needed for these transforms. The fundamental finding is based on the discovery of the relationship between Pascal's matrix and the binomial coefficient. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP ABURDENE, MF (reprint author), BUCKNELL UNIV,DEPT ELECT ENGN,LEWISBURG,PA 17837, USA. NR 12 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 0923-6082 J9 MULTIDIM SYST SIGN P JI Multidimens. Syst. Signal Process. PD JUL PY 1994 VL 5 IS 3 BP 301 EP 305 DI 10.1007/BF00980712 PG 5 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA NP917 UT WOS:A1994NP91700007 ER PT J AU HOF, M BREMERICH, M MENN, W PFEIFER, C REIMER, O SIMON, M MITCHELL, JW BARBIER, LM CHRISTIAN, ER ORMES, JF STREITMATTER, RE GOLDEN, RL STOCHAJ, SJ AF HOF, M BREMERICH, M MENN, W PFEIFER, C REIMER, O SIMON, M MITCHELL, JW BARBIER, LM CHRISTIAN, ER ORMES, JF STREITMATTER, RE GOLDEN, RL STOCHAJ, SJ TI PERFORMANCE OF DRIFT CHAMBERS IN A MAGNETIC RIGIDITY SPECTROMETER FOR MEASURING THE COSMIC-RADIATION SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Article ID RAY; RESOLUTION AB A drift chamber tracking system was developed and flown as part of the IMAX balloon-borne magnetic spectrometer. The drift chamber uses a hexagonal drift-cell structure and is filled with pure CO2 gas. It operated with high efficiency in the strong and inhomogenous field of a superconducting magnet, demonstrating a spatial resolution of better than 100 mum over most of the drift path for singly charged particles, as well as for helium and lithium nuclei. The drift chamber portion of the spectrometer achieved a maximum detectable rigidity of 175 and 250 GV/c for protons and helium respectively. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NEW MEXICO STATE UNIV,LAS CRUCES,NM 88003. RP HOF, M (reprint author), UNIV SIEGEN,DEPT PHYS,D-57068 SIEGEN,GERMANY. RI Christian, Eric/D-4974-2012; Reimer, Olaf/A-3117-2013 OI Christian, Eric/0000-0003-2134-3937; Reimer, Olaf/0000-0001-6953-1385 NR 22 TC 32 Z9 32 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9002 J9 NUCL INSTRUM METH A JI Nucl. Instrum. Methods Phys. Res. Sect. A-Accel. Spectrom. Dect. Assoc. Equip. PD JUL 1 PY 1994 VL 345 IS 3 BP 561 EP 569 DI 10.1016/0168-9002(94)90516-9 PG 9 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA NV681 UT WOS:A1994NV68100026 ER PT J AU CHAO, TH LAU, B MICELI, WJ AF CHAO, TH LAU, B MICELI, WJ TI OPTICAL IMPLEMENTATION OF A MATCHING PURSUIT FOR IMAGE REPRESENTATION SO OPTICAL ENGINEERING LA English DT Article DE ADAPTIVE WAVELET TRANSFORMS; MATCHING PURSUITS; IMAGE REPRESENTATION; PATTERN RECOGNITION; OPTICAL PROCESSING AB We have developed a technique for image analysis, representation, and decomposition. This technique was motivated by Mallat and Zhang's matching-pursuit algorithm. We have altered and simplified the mechanics of this algorithm to enable an extremely fast implementation via optical processing. Initial computer simulations show that our algorithm is capable of decomposing and representing a 2-D image as a linear combination of basis images with both high speed and high fidelity. C1 OFF NAVAL RES,ARLINGTON,VA 22217. RP CHAO, TH (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 4 TC 3 Z9 3 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 JUL PY 1994 VL 33 IS 7 BP 2303 EP 2309 DI 10.1117/12.174456 PG 7 WC Optics SC Optics GA NX463 UT WOS:A1994NX46300027 ER PT J AU MIDDLETON, EM TERAMURA, AH AF MIDDLETON, EM TERAMURA, AH TI UNDERSTANDING PHOTOSYNTHESIS, PIGMENT AND GROWTH-RESPONSES INDUCED BY UV-B AND UV-A IRRADIANCES SO PHOTOCHEMISTRY AND PHOTOBIOLOGY LA English DT Article ID PHOTON FLUX-DENSITY; CHLOROPHYLL-B; HIGHER-PLANTS; SOYBEAN LEAVES; PHOTOSYSTEM-II; LIGHT; RADIATION; CAROTENOIDS; PROTEINS; MUTANTS AB Plant response to UV-B (0.290-0.320 mu m) irradiation in controlled environments has been difficult to assess, possibly because plants also respond to UV-A (0.320-0.400 mu m) and visible radiation. Photosynthetic dysfunction is often reported, but effects on photosynthetic pigments have been equivocal. Because UV-A/blue radiation is involved in pigment synthesis, the experimental UV-A irradiation was controlled and this study was conducted under high ambient photosynthetic photon flux (mid-day PPF greater than or equal to 1400 mu mol m(-2) s(-1)). Two biologically effective UV-B irradiances (10.7 and 14.1 kJ m(-2) day(-1)) were utilized and the UV-A irradiances were matched in controls (similar to 5 and 9 kJ m(-2) day(-1)). Normal and two mutant pigment isolines (chlorophyll-deficient, flavonoid-deficient) of soybean cultivar Clark were utilized for comparisons. Many pigment/growth variables exhibited a statistical interaction between spectral quality and quantity. UV-A/blue photoregulation was demonstrated in the UV-A controls. The pigment/growth pattern observed at the lower UV-B irradiance was interpreted as a photosystem II response similar to shade adaptation, suggesting phytochrome involvement in UV-B irradiation responses. On the other hand, two variables most commonly observed to manifest UV-B-induced effects-decreased photosynthesis and increased leaf flavonoid content-exhibited no interactions due to UV exposure or spectral quality. In general, the observed response patterns indicated either moderation of UV-B-induced responses by UV-A/blue radiation, or coaction between them, and provides an explanation for the common failure to demonstrate fluence-related responses in UV-B experiments. C1 UNIV MARYLAND,DEPT BOT,COLL PK,MD 20744. RP MIDDLETON, EM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771, USA. NR 49 TC 78 Z9 78 U1 1 U2 9 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 JUL PY 1994 VL 60 IS 1 BP 38 EP 45 PG 8 WC Biochemistry & Molecular Biology; Biophysics SC Biochemistry & Molecular Biology; Biophysics GA NX706 UT WOS:A1994NX70600004 ER PT J AU TRIPATHI, RK TOWNSEND, LW AF TRIPATHI, RK TOWNSEND, LW TI BOSE-CONDENSATION OF NUCLEI IN HEAVY-ION COLLISIONS SO PHYSICAL REVIEW C LA English DT Note ID GAS PHASE-TRANSITION; FRAGMENTATION; MATTER AB Using a fully self-consistent quantum statistical model, we demonstrate the possibility of Bose condensation of nuclei in heavy ion collisions. The most favorable conditions of high densities and low temperatures are usually associated with astrophysical processes and may be difficult to achieve in heavy ion collisions. Nonetheless, some suggestions for the possible experimental verification of the existence of this phenomenon are made. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP TRIPATHI, RK (reprint author), CHRISTOPHER NEWPORT UNIV,NEWPORT NEWS,VA 23606, USA. NR 22 TC 6 Z9 6 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2813 J9 PHYS REV C JI Phys. Rev. C PD JUL PY 1994 VL 50 IS 1 BP R7 EP R9 DI 10.1103/PhysRevC.50.R7 PG 3 WC Physics, Nuclear SC Physics GA NZ567 UT WOS:A1994NZ56700003 PM 9969695 ER PT J AU NOEVER, DA CRONISE, RJ AF NOEVER, DA CRONISE, RJ TI WEIGHTLESS BUBBLE LATTICES - A CASE OF FROTH WICKING SO PHYSICS OF FLUIDS LA English DT Article ID SOAP FROTH; FOAM AB In the absence of gravity drainage, froth wicking draws excess fluid onto a bubble lattice. Capillary forces only cause fluid transport; a moving front moves stably and without fluid fingering among a constant velocity bubble-fluid contact line. This percolation of fluid crawling up the lattice shows (1) fluid coverage on lattice borders varies linearly with available surface area (proportional to lattice perimeter); (2) fluid accelerates through regions or nests of high bubble density (number of bubbles cm-2). The development of nearly two-dimensional bubble lattices in variable gravity (step function between 0.01 and 1.8 times earthly gravity) are examined experimentally and a zeroth-order model for froth wetting is presented. which captures many of the principal observations. Possible applications for bubble lattices include adhesion casting of metals and separation of biological cells, bacteria, and particles. RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES-76,HUNTSVILLE,AL 35812, USA. NR 20 TC 19 Z9 19 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD JUL PY 1994 VL 6 IS 7 BP 2493 EP 2500 DI 10.1063/1.868197 PG 8 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA NU225 UT WOS:A1994NU22500025 ER PT J AU ELHADY, NM ZANG, TA PIOMELLI, U AF ELHADY, NM ZANG, TA PIOMELLI, U TI APPLICATION OF THE DYNAMIC SUBGRID-SCALE MODEL TO AXISYMMETRICAL TRANSITIONAL BOUNDARY-LAYER AT HIGH-SPEED (VOL 6, PG 1299, 1994) SO PHYSICS OF FLUIDS LA English DT Correction, Addition C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. UNIV MARYLAND,DEPT MECH ENGN,COLL PK,MD 20742. RP ELHADY, NM (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23666, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD JUL PY 1994 VL 6 IS 7 BP 2551 EP 2551 DI 10.1063/1.868144 PG 1 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA NU225 UT WOS:A1994NU22500032 ER PT J AU SIREGAR, E STRIBLING, WT GOLDSTEIN, ML AF SIREGAR, E STRIBLING, WT GOLDSTEIN, ML TI ON THE DYNAMICS OF A PLASMA VORTEX STREET AND ITS TOPOLOGICAL SIGNATURES SO PHYSICS OF PLASMAS LA English DT Article ID MIXING LAYER; BREAKDOWN; HELICITY; MODEL; RECONNECTION; TURBULENCE; TUBES; FLOW AB A plasma vortex street configuration can evolve when two velocity and one magnetic shear layer interact strongly. A study of the interaction between two- and three-dimensional plasma modes and a mean sheared magnetic field is undertaken using a three-dimensional magnetohydrodynamic spectral Galerkin computation. The initial state is a simple magnetic shear in a plane perpendicular to the plasma velocity shear plane. In a very weak magnetic field, secondary instabilities (three-dimensional modes), expressed by the kinking of vortex tubes, lead to plasma flow along and around the axes of the vortex cores, creating characteristic patterns of kinetic helicity and linkages between vortex filaments. Three-dimensionality leads to the vortex breakdown process. A strong sheared magnetic field inhibits the kinking of vortex tubes, maintaining two-dimensionality. This inhibits vortex breakdown over long dynamical times. There is an anticorrelation in time between linkage indices of the vortex filament (related to kinetic helicity), suggesting that the ellipticity axes of the vortex cores along the street undergo a global inphase evolution. This anticorrelation has a dynamical interpretation. It extends to a relaxing plasma in the Navier-Stokes flow notion that helical regions of opposite helicities interact and screen each other off so that the global helicity remains bounded. RP SIREGAR, E (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Goldstein, Melvyn/B-1724-2008 NR 26 TC 10 Z9 10 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-664X J9 PHYS PLASMAS JI Phys. Plasmas PD JUL PY 1994 VL 1 IS 7 BP 2125 EP 2134 DI 10.1063/1.870610 PG 10 WC Physics, Fluids & Plasmas SC Physics GA NX009 UT WOS:A1994NX00900004 ER PT J AU HYUNG, S ALLER, LH FEIBELMAN, WA AF HYUNG, S ALLER, LH FEIBELMAN, WA TI THE SPECTRUM OF THE PLANETARY-NEBULA IC-418 SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID CENTRAL STAR; STELLAR ATMOSPHERES; NEUTRAL HYDROGEN; ABUNDANCES; EVOLUTION; CARBON; MODELS AB A detailed high-spectral-resolution study of the spectrum of IC 418 is made for the region 3650 to 10050 angstrom, using the Hamilton echelle spectrograph of Lick Observatory, and of the UV spectral region with archival International Ultraviolet Explorer (IUE) data. From high-resolution images in both the near- and mid-infrared, Hora et al. (1993) showed that IC 418 probably has a compact shell interior to the detached, well-known, main shell emission. If one assumes a black body or Hubeny (or standard LTE) model atmosphere energy distribution, it does not appear possible to construct a fully satisfactory nebula model that will simultaneously represent the Hbeta flux, the [O III]5007/Hbeta ratio, and the scale of this planetary nebula (PN). Fortunately, IUE and IR data supply information on ions in addition to those optically observed so that the chemical composition can be reasonably well established by summing over concentrations of observed ions. In spite of the fact that IC 418 is carbon rich in sense of having a C/O ratio exceeding the solar value, it is a ''metal-poor'' object. Possibly it resembles IC 4997 but in a more advanced evolutionary phase. The central star is variable and has a strong wind. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP HYUNG, S (reprint author), UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024, USA. NR 50 TC 31 Z9 31 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 JUL PY 1994 VL 106 IS 701 BP 745 EP 755 DI 10.1086/133438 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA184 UT WOS:A1994PA18400008 ER PT J AU FEIBELMAN, WA AF FEIBELMAN, WA TI X-RAY PLANETARY-NEBULAE SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID CENTRAL STAR TEMPERATURES; EMISSION AB A study of IUE archival low-dispersion spectra was conducted in an attempt to correlate the C IV/He II and C III]/C IV emission line ratios as indicators of X-ray emission in planetary nebulae. The presence of P Cygni lines revealed a strong correlation for planetaries known to exhibit X-ray emission. Of the twelve planetaries definitely known to emit X rays, eleven have been observed with IUE and all but one show ultraviolet lines with very strong P Cygni profiles for at least one, and sometimes all, of the N V, O V, or C IV lines which are indicative of strong stellar winds. Twenty planetary nebulae are identified as likely candidates for X-ray sources, based on their high IUE emission line flux ratios for C IV/He II as well as prevalence of P Cygni lines. Some misconceptions based on outdated IUE data are corrected. RP FEIBELMAN, WA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 684 1,GREENBELT,MD 20771, USA. NR 28 TC 12 Z9 12 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 JUL PY 1994 VL 106 IS 701 BP 756 EP 764 DI 10.1086/133439 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA184 UT WOS:A1994PA18400009 ER PT J AU ELLISON, DC REYNOLDS, SP BORKOWSKI, K CHEVALIER, R COX, DP DICKEL, JR PISARSKI, R RAYMOND, J SPANGLER, SR VOLK, HJ WEFEL, JP AF ELLISON, DC REYNOLDS, SP BORKOWSKI, K CHEVALIER, R COX, DP DICKEL, JR PISARSKI, R RAYMOND, J SPANGLER, SR VOLK, HJ WEFEL, JP TI SUPERNOVA-REMNANTS AND THE PHYSICS OF STRONG SHOCK-WAVES SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID COSMIC-RAY ACCELERATION; PARTICLE-ACCELERATION; OBLIQUE SHOCKS; PARALLEL SHOCK; INJECTION; ENERGY; TYCHO AB This paper reports on a Workshop on Supernova Remnants and the Physics of Strong Shock Waves hosted by North Carolina State University at Raleigh, North Carolina, September 16-18, 1993. The workshop brought together observers, shock theorists, cosmic-ray specialists, and simulators to address the role supernova remnants can play in furthering our understanding of the complex plasma physics associated with collisionless shocks and particle acceleration. Over fifty scientists presented papers on various aspects of supernova remnants. In lieu of a proceedings volume, we present here a synopsis of the workshop, in the form of brief summaries of each workshop session. C1 UNIV MARYLAND, DEPT ASTRON, COLLEGE PK, MD 20742 USA. UNIV VIRGINIA, DEPT ASTRON, CHARLOTTESVILLE, VA 22903 USA. UNIV WISCONSIN, DEPT PHYS, MADISON, WI 53706 USA. UNIV ILLINOIS, DEPT ASTRON, URBANA, IL 61801 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. UNIV IOWA, DEPT PHYS & ASTRON, IOWA CITY, IA 52242 USA. MAX PLANCK INST NUCL PHYS, W-6900 HEIDELBERG 1, GERMANY. LOUISIANA STATE UNIV, DEPT PHYS & ASTRON, BATON ROUGE, LA 70803 USA. RP ELLISON, DC (reprint author), N CAROLINA STATE UNIV, DEPT PHYS, RALEIGH, NC 27695 USA. NR 52 TC 20 Z9 20 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 1427 E 60TH ST, CHICAGO, IL 60637-2954 USA SN 0004-6280 J9 PUBL ASTRON SOC PAC JI Publ. Astron. Soc. Pac. PD JUL PY 1994 VL 106 IS 701 BP 780 EP 797 DI 10.1086/133442 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PA184 UT WOS:A1994PA18400012 ER PT J AU PENDALL, EG HARDEN, JW TRUBMORE, SE CHADWICK, OA AF PENDALL, EG HARDEN, JW TRUBMORE, SE CHADWICK, OA TI ISOTOPIC APPROACH TO SOIL CARBONATE DYNAMICS AND IMPLICATIONS FOR PALEOCLIMATIC INTERPRETATIONS SO QUATERNARY RESEARCH LA English DT Article ID PEDOGENIC CARBONATE; MOJAVE-DESERT; ARID-ZONE; PALEOSOLS; CALICHE; MODEL; CHEMISTRY; PAKISTAN; NEVADA; OXYGEN AB The radiocarbon content and stable isotope composition of soil carbonate are best described by a dynamic system in which isotopic reequilibration occurs as a result of recurrent dissolution and reprecipitation. Depth of water penetration into the soil profile, as well as soil age, determines the degree of carbonate isotope reequilibration. We measured deltaC-13, deltaO-18, and radiocarbon content of gravel rinds and fine (<2 mm) carbonate in soils of 3 different ages (1000, 3800, and 6300 C-14 yr B.P.) to assess the degree to which they record and preserve a climatic signal. In soils developing in deposits independently dated at 3800 and 6300 radiocarbon yr B.P., carbonate radiocarbon content above 40 cm depth suggests continual dissolution and reprecipitation, presumably due to frequent wetting events. Between 40 and 90 cm depth, fine carbonate is dissolved and precipitated as rinds that are not redissolved subsequently. Below 90 cm depth in these soils, radiocarbon content indicates that inherited, fine carbonate undergoes little dissolution and reprecipitation. In the 3800- and 6300-yr-old soils, deltaC-13 in rind and fine carbonate follows a decreasing trend with depth, apparently in equilibrium with modem soil gas, as predicted by a diffusive model for soil CO2. DeltaO-18 also decreases with depth due to greater evaporative enrichment above 50 cm depth. In contrast, carbonate isotopes in a 1000-yr-old deposit do not reflect modern conditions even in surficial horizons; this soil has not undergone significant pedogenesis. There appears to be a lag of at least 1000 but less than 3800 yr before carbonate inherited with parent material is modified by ambient climatic conditions. Although small amounts of carbonate are inherited with the parent material, the rate of pedogenic carbonate accumulation indicates that Ca is derived primarily from eolian and rainfall sources. A model describing carbonate input and radiocarbon decay suggests that fine carbonate below 90 cm is mostly detrital (inherited) and that carbonate rinds have been forming pedogenically at a constant rate since alluvial fans were deposited. (C) 1994 University of Washington. C1 US GEOL SURVEY,MENLO PK,CA 94025. UNIV CALIF IRVINE,DEPT GEOSCI,IRVINE,CA 92717. JET PROP LAB,PASADENA,CA 91109. OI Pendall, Elise/0000-0002-1651-8969 NR 41 TC 52 Z9 58 U1 1 U2 14 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 JUL PY 1994 VL 42 IS 1 BP 60 EP 71 DI 10.1006/qres.1994.1054 PG 12 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA PB179 UT WOS:A1994PB17900006 ER PT J AU YUEH, SH KWOK, R LI, FK NGHIEM, SV WILSON, WJ KONG, JA AF YUEH, SH KWOK, R LI, FK NGHIEM, SV WILSON, WJ KONG, JA TI POLARIMETRIC PASSIVE REMOTE-SENSING OF OCEAN WIND VECTORS SO RADIO SCIENCE LA English DT Article ID SEA-SURFACE; MICROWAVE; MODEL AB This paper investigates the theory of polarimetric passive remote sensing of wind-generated sea surfaces and the potential application of polarimetric radiometry to ocean wind remote sensing. Theoretical polarimetric emission coefficients of small-scale sea surfaces are evaluated using the small perturbation method (SPM). The SPM is derived to second order and applied to the Stokes vectors of thermal emission from random rough dielectric surfaces described by anisotropic directional spectra. To verify the accuracy of the SPM, a Monte Carlo simulation is performed to calculate the Stokes vectors of the emission from the simulated one-dimensional random rough surfaces with a power law spectrum for various observation angles and surface parameters. The theoretical results of the SPM for all four Stokes parameters are in excellent agreement with the numerical results obtained from the Monte Carlo simulation. Moreover, the second-order coherent fields are indispensable in the theoretical evaluation of the third and fourth Stokes parameters. Otherwise, the reflectivities of random rough surfaces would be significantly overestimated, and the sips of the third and fourth Stokes parameters would be incorrect. The SPM is then applied to small-scale sea surfaces described by an empirical sea surface spectrum. It is found that the azimuthal signatures of Stokes parameters agree qualitatively well with aircraft Ku-band radiometer data. Theoretical model functions of the Stokes parameters are illustrated. Advantages of wind direction retrieval using polarimetric Q and U measurements are discussed, and it is expected that a spaceborne polarimetric radiometer has a potential of providing wind vector measurements with uniform accuracy across all parts of swath. C1 MIT,ELECTR RES LAB,CAMBRIDGE,MA 02139. RP YUEH, SH (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 19 TC 67 Z9 71 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD JUL-AUG PY 1994 VL 29 IS 4 BP 799 EP 814 DI 10.1029/94RS00450 PG 16 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA PA127 UT WOS:A1994PA12700011 ER PT J AU ROSSI, RE DUNGAN, JL BECK, LR AF ROSSI, RE DUNGAN, JL BECK, LR TI KRIGING IN THE SHADOWS - GEOSTATISTICAL INTERPOLATION FOR REMOTE-SENSING SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID DIGITAL IMAGES; AUTO-CORRELATION; REGULARIZATION; CROP AB It is often useful to estimate obscured or missing remotely sensed data. Traditional interpolation methods, such as nearest-neighbor or bilinear resampling, do not take full advantage of the spatial information in the image. An alternative method, a geostatistical technique known as indicator kriging, is described and demonstrated using a Landsat Thematic Mapper image in southern Chiapas, Mexico. The image was first classified into pasture and nonpasture land cover. For each pixel that was obscured by cloud or cloud shadow, the probability that it was pasture was assigned by the algorithm. An exponential omnidirectional variogram model was used to characterize the spatial continuity of the image for use in the kriging algorithm. Assuming a cutoff probability level of 50%, the error was shown to be 17% with no obvious spatial bias but with some tendency to categorize nonpasture as pasture (overestimation). While this is a promising result, the methods practical application in other missing data problems for remotely sensed images will depend on the amount and spatial pattern of the unobscured pixels and missing pixels and the success of the spatial continuity model used. C1 NASA, AMES RES CTR, JOHNSON CONTROLS WORLD SERV, MS 242-4, MOFFETT FIELD, CA 94035 USA. ISAAKS & CO, REDWOOD CITY, CA USA. RI Dungan, Jennifer/G-9921-2016 OI Dungan, Jennifer/0000-0002-4863-1616 NR 28 TC 59 Z9 60 U1 2 U2 9 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0034-4257 EI 1879-0704 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD JUL PY 1994 VL 49 IS 1 BP 32 EP 40 DI 10.1016/0034-4257(94)90057-4 PG 9 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA NZ545 UT WOS:A1994NZ54500004 ER PT J AU HARDING, LW ITSWEIRE, EC ESAIAS, WE AF HARDING, LW ITSWEIRE, EC ESAIAS, WE TI ESTIMATES OF PHYTOPLANKTON BIOMASS IN THE CHESAPEAKE BAY FROM AIRCRAFT REMOTE-SENSING OF CHLOROPHYLL CONCENTRATIONS, 1989-92 SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID PARTIALLY STRATIFIED ESTUARY; SAN-FRANCISCO BAY; DELAWARE ESTUARY; ANNUAL CYCLE; NUTRIENT; DYNAMICS; VARIABILITY; LIMITATION; CHEMISTRY; ANOXIA AB Aircraft remote sensing of surface chlorophyll concentrations with NASA's Ocean Data Acquisition System (ODAS) was used to determine the seasonal and interannual dynamics of phytoplankton biomass in the Chesapeake Bay from 1989 to 1992. Flights were conducted at a frequency of 1-2 per week from late winter through early fall, and were scheduled to coincide with shipboard sampling as weather permitted. The primary sources of in situ data for developing and validating biomass algorithms were monitoring cruises sponsored by the Chesapeake Bay Program (CBP) and the NSF-sponsored Land Margin Ecosystem Research (LMER) program of the University of Maryland. The general approach was to recover estimates of biomass from the relationship of surface chlorophyll to the concentration of vertically-integrated chlorophyll weighted bathymetrically. The seasonally and annually specific relations used to estimate biomass were then applied to ODAS estimates of surface chlorophyll for each of >90 flights to produce a time series of total phytoplankton biomass (in metric tons of chlorophyll) for the Chesapeake Bay. Estimates of algal biomass averaged approximately 500 metric tons, with maximum values of 1400 metric tons in spring 1990. These values are in agreement with estimates computed from the integrated vertical profiles of the CBP database using a 3D interpolator model. The total biomass of phytoplankton during the spring bloom of 1990 was significantly higher than in 1989, 1991, and 1992. The causes of these interannual differences are discussed in terms of variations in Susquehanna River flow and nutrient loading to the estuary. C1 UNIV MARYLAND,CTR ENVIRONM & ESTUARINE STUDIES,HORN POINT ENVIRONM LABS,CAMBRIDGE,MD. NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,GREENBELT,MD 20771. NATL SCI FDN,DIV OCEAN SCI,WASHINGTON,DC 20550. JOHNS HOPKINS UNIV,DEPT GEOG & ENVIRONM ENGN,BALTIMORE,MD 21218. RP HARDING, LW (reprint author), UNIV MARYLAND,SEA GRANT COLL,0112 SKINNER HALL,COLLEGE PK,MD 20742, USA. NR 41 TC 21 Z9 21 U1 2 U2 6 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 JUL PY 1994 VL 49 IS 1 BP 41 EP 56 DI 10.1016/0034-4257(94)90058-2 PG 16 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA NZ545 UT WOS:A1994NZ54500005 ER PT J AU PEREZ, M THE, PS AF PEREZ, M THE, PS TI THE CLUMPY ACCRETION IN HERBIG AE/BE STARS SO REVISTA MEXICANA DE ASTRONOMIA Y ASTROFISICA LA English DT Article DE STARS, EMISSION-LINE; STARS, PRE-MAIN-SEQUENCE; CIRCUMSTELLAR MATTER ID INTERMEDIATE-MASS STARS; YOUNG STELLAR OBJECTS; T-TAURI STARS; INFRARED-EMISSION; CIRCUMSTELLAR GAS; BETA-PICTORIS; DISKS; VARIABILITY; ULTRAVIOLET; ORIONIS AB In the last few years much multiwavelength observational evidence has accumulated suggesting that in some of the intermediate-mass Herbig Ae/Be stars, gas is accreting toward the central source at large_ terminal velocities. The most direct proof of this phenomenon has come from the analysis of the ultraviolet lines. Concurrent and complementary support for this interpretation are provided by diverse observations described here. We review the strong observational evidence from several of these objects in support of the concept of clumpy mass accretion occurring in their circumstellar environments. C1 UNIV AMSTERDAM, STERRENKUNDIG INST ANTON PANNEKOEK, 1098 SJ AMSTERDAM, NETHERLANDS. RP PEREZ, M (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CSC, IUE OBSERV, CODE 6849, GREENBELT, MD 20815 USA. NR 32 TC 1 Z9 1 U1 0 U2 0 PU UNIV NACIONAL AUTONOMA MEXICO, INST DE ASTRONOMIA PI MEXICO CITY PA APDO POSTAL 70-264, MEXICO CITY 04510, MEXICO SN 0185-1101 J9 REV MEX ASTRON ASTR JI Rev. Mex. Astron. Astrofis. PD JUL PY 1994 VL 29 SI SI BP 54 EP 58 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PB640 UT WOS:A1994PB64000008 ER PT J AU ROMAN, NG AF ROMAN, NG TI SERVICES OF THE UNITED-STATES NSSDC AND THE ADC SO REVISTA MEXICANA DE ASTRONOMIA Y ASTROFISICA LA English DT Article; Proceedings Paper CT Symposium on Stars, Gas and Dust in the Galaxy to Honor Eugene E Mendoza V CY AUG 25-27, 1993 CL MEXICO CITY, MEXICO SP UNIV NACL AUTONOMA MEXICO, INST ASTRON, CONSEJO NACL CIEN & TECHNOL, UNIV NACL AUTONOMA MEXICO, DIREC ASUNTOS PERSONAL ACAD, UNIV NACL AUTONOMA MEXICO, COORDINAC INVESTIGAC CIENT DE CATALOGS AB The U.S. National Space Science Data Center (NSSDC) provides several services which are of use to astronomers. The most important of these is the Astronomical Data Center (ADC) which currently contains about 700 astronomical catalogs, primarily from ground-based observations. Most of these are available electronically at no cost to anyone with a connection to Internet or Decnet. They can also be obtained in other forms at the cost of preparation and distribution. The NSSDC also contains most data from U.S. scientific satellites and many from other countries. Through its NASA On-line Data Information Services (NODIS), it also provides a directory of other data sets and services for both space and, for astronomy, ground-based data. The NSSDC distributes a number of CDROMs including one with 114 of the most requested astronomical catalogs. Others contain planetary images and Halley Watch observations. Other services are available through NODIS or by referral from NODIS. The ADC is also cooperating with the American Astronomical Society (AAS) to provide on-line access to AAS information and abstracts from astronomical publications. RP ROMAN, NG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NATL SPACE SCI DATA CTR,4620 N PK AVE,APT 306W,CHEVY CHASE,MD 20815, USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU UNIV NACIONAL AUTONOMA MEXICO, INST DE ASTRONOMIA PI MEXICO CITY PA APDO POSTAL 70-264, MEXICO CITY 04510, MEXICO SN 0185-1101 J9 REV MEX ASTRON ASTR JI Rev. Mex. Astron. Astrofis. PD JUL PY 1994 VL 29 SI SI BP 59 EP 62 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA PB640 UT WOS:A1994PB64000009 ER PT J AU HILL, F FISCHER, G GRIER, J LEIBACHER, JW JONES, HB JONES, PP KUPKE, R STEBBISN, RT AF HILL, F FISCHER, G GRIER, J LEIBACHER, JW JONES, HB JONES, PP KUPKE, R STEBBISN, RT TI THE GLOBAL OSCILLATION NETWORK GROUP SITE SURVEY .1. DATA-COLLECTION AND ANALYSIS-METHODS SO SOLAR PHYSICS LA English DT Article ID SOLAR AB The Global Oscillation Network Group (GONG) Project is planning to place a set of instruments around the world to observe solar oscillations as continuously as possible for at last three years. The Project has now chosen the sites that will comprise the network. This paper describes the methods of data collection and analysis that were used to make this decision. Solar irradiance data were collected with a one-minute cadence at fifteen sites around the world and analyzed to produce statistics of cloud cover, atmospheric extinction, and transparency power spectra at the individual sites. Nearly 200 reasonable six-site networks were assembled from the individual stations, and a set of statistical measures of the performance of the networks was analyzed using a principal component analysis. An accompanying paper presents the results of the survey. C1 UNIV UTAH, DEPT MATH, SALT LAKE CITY, UT 84112 USA. NASA, GSFC, SW STN, TUCSON, AZ 85726 USA. UNIV ARIZONA, CTR COMP & INFORMAT TECHNOL, TUCSON, AZ 85721 USA. UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. UNIV COLORADO, JOINT INST LAB ASTROPHYS, BOULDER, CO 80309 USA. RP HILL, F (reprint author), NATL OPT ASTRON OBSERV, NATL SOLAR OBSERV, TUCSON, AZ 85726 USA. NR 26 TC 21 Z9 21 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD JUL PY 1994 VL 152 IS 2 BP 321 EP 349 DI 10.1007/BF00680443 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ877 UT WOS:A1994NZ87700002 ER PT J AU HILL, F FISCHER, G FORGACH, S GRIER, J LEIBACHER, JW JONES, HP JONES, PB KUPKE, R STEBBISN, RT CLAY, DW INGRAM, RL LIBBRECHT, KG ZIRIN, H ULRICH, RK WEBSTER, L HIEDA, LS LABONTE, BJ LU, WMT SOUSA, EM GARCIA, GJ YASUKAWA, EA KENNEWELL, JA COLE, DG ZHEN, H SUMIN, X BHATNAGAR, A AMBASTHA, A ALKHASHLAN, AS ABDULSAMAD, MS BENKHALDOUN, Z KADIRI, S SANCHEZ, F PALLE, PL DUHALDE, O SOLIS, H SAA, O GONZALEZ, R AF HILL, F FISCHER, G FORGACH, S GRIER, J LEIBACHER, JW JONES, HP JONES, PB KUPKE, R STEBBISN, RT CLAY, DW INGRAM, RL LIBBRECHT, KG ZIRIN, H ULRICH, RK WEBSTER, L HIEDA, LS LABONTE, BJ LU, WMT SOUSA, EM GARCIA, GJ YASUKAWA, EA KENNEWELL, JA COLE, DG ZHEN, H SUMIN, X BHATNAGAR, A AMBASTHA, A ALKHASHLAN, AS ABDULSAMAD, MS BENKHALDOUN, Z KADIRI, S SANCHEZ, F PALLE, PL DUHALDE, O SOLIS, H SAA, O GONZALEZ, R TI THE GLOBAL OSCILLATION NETWORK GROUP SITE SURVEY .2. RESULTS SO SOLAR PHYSICS LA English DT Article ID SOLAR AB The Global Oscillation Network Group (GONG) Project will place a network of instruments around the world to observe solar oscillations as continuously as possible for three years. The Project has now chosen the six network sites based on analysis of survey data from fifteen sites around the world. The chosen sites are: Big Bear Solar Observatory, California; Mauna Loa Solar Observatory, Hawaii: Learmonth Solar Observatory, Australia; Udaipur Solar Observatory, India; Observatorio del Teide, Tenerife; and Cerro Tololo Interamerican Observatory, Chile. Total solar intensity at each site yields information on local cloud cover, extinction coefficient, and transparency fluctuations. In addition, the performance of 192 reasonable networks assembled from the individual site records is compared using a statistical principal components analysis. An accompanying paper describes the analysis methods in detail; here we present the results of both the network and individual site analyses. The selected network has a duty cycle of 93.3%, in good agreement with numerical simulations. The power spectrum of the network observing window shows a first diurnal sidelobe height of 3 x 10(-4) with respect to the central component, an improvement of a factor of 1300 over a single site. The background level of the network spectrum is lower by a factor of 50 compared to a single-site spectrum. C1 UNIV UTAH, DEPT MATH, SALT LAKE CITY, UT 84112 USA. UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. NASA, GSFC, NOAO, SW STN, TUCSON, AZ 85726 USA. UNIV ARIZONA, CTR COMP & INFORMAT TECHNOL, TUCSON, AZ 85721 USA. UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. UNIV COLORADO, JOINT INST LAB ASTROPHYS, BOULDER, CO 80309 USA. ARIZONA WESTERN COLL, YUMA, AZ 85366 USA. CALTECH, BIG BEAR SOLAR OBSERV, PASADENA, CA 91125 USA. UNIV CALIF LOS ANGELES, MT WILSON OBSERV, LOS ANGELES, CA 90024 USA. HIGH ALTITUDE OBSERV, MAUNA LOA SOLAR OBSERV, BOULDER, CO 80307 USA. IPS RADIO & SPACE SERV, LEARMONTH SOLAR OBSERV, W CHATSWOOD, NSW, AUSTRALIA. UDAIPUR SOLAR OBSERV, UDAIPUR, INDIA. ACAD SINICA XINJIANG, URUMQI, PEOPLES R CHINA. CTR NATL COORDINAT & PLANIFICAT RECH SCI & TECH, RABAT, MOROCCO. CARNEGIE INST WASHINGTON OBSERV, LAS CAMPANAS OBSERV, PASADENA, CA 91101 USA. NATL OPT ASTRON OBSERV, CERRO TOLOLO INTERAMER OBSERV, TUCSON, AZ 85726 USA. RP HILL, F (reprint author), NATL OPT ASTRON OBSERV, NATL SOLAR OBSERV, TUCSON, AZ 85726 USA. RI Lin, Aoxiang/C-9978-2009; Palle, Pere/H-4720-2015 NR 17 TC 34 Z9 36 U1 0 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD JUL PY 1994 VL 152 IS 2 BP 351 EP 379 DI 10.1007/BF00680444 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NZ877 UT WOS:A1994NZ87700003 ER PT J AU RAMSEY, BD AUSTIN, RA DECHER, R AF RAMSEY, BD AUSTIN, RA DECHER, R TI INSTRUMENTATION FOR X-RAY ASTRONOMY SO SPACE SCIENCE REVIEWS LA English DT Review ID PROPORTIONAL-COUNTERS; MICROCHANNEL PLATES; RESOLUTION; SPECTROSCOPY; TELESCOPE; DETECTORS; MISSION; SPECTROMETERS; ARRAYS; EXOSAT AB Less than five decades ago, the first X-ray observations of the sky were made using simple devices such as film and geiger counters with crude collimators. These instruments were carried aloft by sounding rockets and made observations lasting only a few minutes at most. Today, orbiting observatories, utilizing high-resolution CCDs at the focus of arc sec optics, have lifetimes measured in years. To maintain the pace of discovery in X-ray astronomy, detectors must continue to evolve into devices of ever increasing sensitivity and sophistication. Further progress depends upon a host of technologies: grazing incidence optics, proportional counters, semiconductors, calorimeters, etc. In this article we present a brief qualitative overview of these technologies and of the principles behind them, as well as some examples of how they are employed in scientific missions for X-ray observations at energies up to 100 keV. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUGHES STX,HUNTSVILLE,AL 35812. RP RAMSEY, BD (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 116 TC 9 Z9 9 U1 2 U2 3 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 1994 VL 69 IS 1-2 BP 139 EP 204 DI 10.1007/BF00756035 PG 66 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NW163 UT WOS:A1994NW16300002 ER PT J AU WATZIN, JG AF WATZIN, JG TI NASA SMALL EXPLORER SPACECRAFT - FLIGHT PROVEN, HIGH-PERFORMANCE, RELIABLE AND STILL SMALL SO SPACE TECHNOLOGY-INDUSTRIAL AND COMMERCIAL APPLICATIONS LA English DT Article AB NASA's Small Explorer (SMEX) Project has developed a series of highly capable small satellites that are being used to support astrophysics and space physics investigations. These satellites, while both small and economical, give up nothing in performance and versatility to the larger satellites developed over the past 15 years within the Explorer Program. Past technology has limited the scientific return that a small satellite could generate. Innovative engineering and new technology advances, however, have increased the potential scientific return of the SMEX spacecraft to a level comparable to larger carriers. The design has struck a balance between mission risk and cost that has allowed for the development of an extremely capable spacecraft which was completed in just three years time. More than just a concept, the first SMEX mission, Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX), has been in orbit since July 1992 and is continuing to perform well. It has proven the merits of this design approach. This paper describes the fundamental strategies and technologies used in developing the design. It outlines the key elements of the system architecture and describes the capabilities and merits of the major subsystems. Major design trade-offs are highlighted. Significant emphasis is placed on the innovative attitude control system which was developed for the SAMPEX mission. This paper also describes the unique SMEX approach to mission operations. RP WATZIN, JG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 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 0892-9270 J9 SPACE TECHNOL JI Space Tech.-Ind. Comm. Appl. PD JUL PY 1994 VL 14 IS 4 BP 269 EP 280 PG 12 WC Engineering, Aerospace SC Engineering GA QG640 UT WOS:A1994QG64000003 ER PT J AU YEOMANS, D AF YEOMANS, D TI THE QUEST FOR COMETS - AN EXPLOSIVE TRAIL OF BEAUTY AND DANGER - LEVY,DH SO NATURE LA English DT Book Review RP YEOMANS, D (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 1 TC 0 Z9 0 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 30 PY 1994 VL 369 IS 6483 BP 716 EP 716 DI 10.1038/369716b0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NU581 UT WOS:A1994NU58100044 ER PT J AU LOWE, RA CHUBB, DL FARMER, SC GOOD, BS AF LOWE, RA CHUBB, DL FARMER, SC GOOD, BS TI RARE-EARTH GARNET SELECTIVE EMITTER SO APPLIED PHYSICS LETTERS LA English DT Article AB Thin film (Ho)-yttrium aluminum garnet (YAG) and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(lambda) almost-equal-to 0.75, I-4(15/2)-I-4(13/2), for Er-YAG and epsilon(lambda) almost-equal-to 0.65, I-5(7)-I-5(8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(lambda)<0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 M(cr), the ram pressure of the stellar wind blows down the atmosphere for r < r(g) and allows the stellar photons to penetrate to greater radii and smaller heights. A slow, ionized outflow produced mainly by diffuse photons is again created for r > r(g); however, it is now dominated by the flow at r(w) (>r(g)), the radius at which the stellar wind ram pressure equals the thermal pressure in the evaporating flow. The mass-loss rate from the disk is of order 6 x 10(-5) M(w-6)v(w8)PHI49(-1/2) M. yr-1, where M(w-6) = M(w)/10(-6) M., yr-1 and V(w8) = v(w)/1000 km s-1 is the stellar wind velocity. The resulting outflow, which also persists for greater than or similar to 10(5) yr may explain many of the more extended (r greater than or similar to 10(16) cm) ultracompact H II regions. Both the weak-wind and the strong-wind models depend entirely on stellar parameters (PHI(i), M*, M(w)) and are independent of disk parameters as long as an extended (r much greater than r(g)), neutral disk exists. We compare both weak-wind and strong-wind model results to the observed radio free-free spectra and luminosities of ultracompact H II regions and to the interesting source MWC 349. C1 UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. Univ Nacl Autonoma Mexico, INST ASTRON, MEXICO CITY 04510, DF, MEXICO. RP HOLLENBACH, D (reprint author), NASA, AMES RES CTR, MS 245-3, MOFFETT FIELD, CA 94035 USA. NR 46 TC 371 Z9 371 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 JUN 20 PY 1994 VL 428 IS 2 BP 654 EP 669 DI 10.1086/174276 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NQ751 UT WOS:A1994NQ75100025 ER PT J AU DEPREE, CG GOSS, WM PALMER, P RUBIN, RH AF DEPREE, CG GOSS, WM PALMER, P RUBIN, RH TI A BIPOLAR OUTFLOW OF IONIZED-GAS IN K3-50A - H76-ALPHA RADIO RECOMBINATION LINE AND CONTINUUM OBSERVATIONS OF K3-50 SO ASTROPHYSICAL JOURNAL LA English DT Article DE H-II REGIONS; ISM, INDIVIDUAL (K3-50); ISM, JETS AND OUTFLOWS; ISM, KINEMATICS AND DYNAMICS; RADIO LINES, ISM ID H-II REGIONS; DYNAMICS AB The H II regions near K3-50 (G70.3 + 1.6) have been imaged at high angular resolution (approximately 1.3'') in the continuum and the recombination lines H76alpha and He76alpha using the Very Large Array (VLA). The helium line is detected in only the brightest component K3-50A while the hydrogen line is detected in three components (K3-50A, B and C1). K3-50A shows a pronounced velocity gradient of approximately 150 km s-1 pc-1 along its major axis (P.A. = 160-degrees); in addition a wide range of line widths are observed, from 20 km s-1 to 65 km s-1. Kinematics from the line data and the morphology of the continuum emission suggest that the ionized material associated with K3-50A is undergoing a high-velocity bipolar outflow. C1 NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. NASA,AMES RES CTR,ASTROPHYS BRANCH,MOFFETT FIELD,CA 94035. RP DEPREE, CG (reprint author), UNIV N CAROLINA,DEPT PHYS & ASTRON,CB 3255,CHAPEL HILL,NC 27599, USA. NR 30 TC 40 Z9 40 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 1994 VL 428 IS 2 BP 670 EP 679 DI 10.1086/174277 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NQ751 UT WOS:A1994NQ75100026 ER PT J AU CANUTO, VM AF CANUTO, VM TI LARGE-EDDY SIMULATION OF TURBULENCE - A SUBGRID SCALE-MODEL INCLUDING SHEAR, VORTICITY, ROTATION, AND BUOYANCY SO ASTROPHYSICAL JOURNAL LA English DT Article DE CONVECTION; METHODS, ANALYTICAL; METHODS, NUMERICAL; TURBULENCE ID STELLAR CONVECTIVE DYNAMOS; STABLY STRATIFIED TURBULENCE; ATMOSPHERIC BOUNDARY-LAYER; REYNOLDS STRESS APPROACH; COMPRESSIBLE CONVECTION; NUMERICAL SIMULATIONS; TEMPERATURE SPECTRA; DEEP ATMOSPHERE; CHANNEL FLOW; MIXED LAYERS AB The Reynolds numbers that characterize geophysical and astrophysical turbulence (Re almost-equal-to 10(8) for the planetary boundary layer and Re almost-equal-to 10(14) for the Sun's interior) are too large to allow a direct numerical simulation (DNS) of the fundamental Navier-Stokes and temperature equations. In fact, the spatial number of grid points N approximately Re9/4 exceeds the computational capability of today's supercomputers. Alternative treatments are the ensemble-time average approach, and/or the volume average approach. Since the first method (Reynolds stress approach) is largely analytical, the resulting turbulence equations entail manageable computational requirements and can thus be linked to a stellar evolutionary code or, in the geophysical case, to general circulation models. In the volume average approach, one carries out a large eddy simulation (LES) which resolves numerically the largest scales, while the unresolved scales must be treated theoretically with a subgrid scale model (SGS). Contrary to the ensemble average approach, the LES + SGS approach has considerable computational requirements. Even if this prevents (for the time being) a LES + SGS model to be linked to stellar or geophysical codes, it is still of the greatest relevance as an ''experimental tool'' to be used, inter alia, to improve the parameterizations needed in the ensemble average approach. Such a methodology has been successfully adopted in studies of the convective planetary boundary layer. Experience with the LES + SGS approach from different fields has shown that its reliability depends on the healthiness of the SGS model for numerical stability as well as for physical completeness. At present, the most widely used SGS model, the Smagorinsky model, accounts for the effect of the shear induced by the large resolved scales on the unresolved scales but does not account for the effects of buoyancy, anisotropy, rotation, and stable stratification. The latter phenomenon, which affects both geophysical and astrophysical turbulence (e.g,, oceanic structure and convective overshooting in stars), has been singularly difficult to account for in turbulence modeling. For example, the widely used model of Deardorff has not been confirmed by recent LES results. As of today, there is no SGS model capable of incorporating buoyancy, rotation, shear, anisotropy, and stable stratification (gravity waves). In this paper, we construct such a model which we call CM (complete model). We also present a hierarchy of simpler algebraic models (called AM) of varying complexity. Finally, we present a set of models which are simplified even further (called SM), the simplest of which is the Smagorinsky-Lilly model. The incorporation of these models into the presently available LES codes should begin with the SM, to be followed by the AM and finally by the CM. RP NASA, GODDARD INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. NR 148 TC 50 Z9 52 U1 0 U2 3 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1994 VL 428 IS 2 BP 729 EP 752 DI 10.1086/174281 PN 1 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NQ751 UT WOS:A1994NQ75100030 ER PT J AU MOORE, MH FERRANTE, RF HUDSON, RL NUTH, JA DONN, B AF MOORE, MH FERRANTE, RF HUDSON, RL NUTH, JA DONN, B TI INFRARED-SPECTRA OF CRYSTALLINE PHASE ICES CONDENSED ON SILICATE SMOKES AT T-LESS-THAN-20-K SO ASTROPHYSICAL JOURNAL LA English DT Article DE COMETS, GENERAL; DUST, EXTINCTION; INFRARED, GENERAL; ISM, MOLECULES; LINE, IDENTIFICATION; TECHNIQUES, SPECTROSCOPIC ID STARS; WATER AB Infrared spectra of H2O, CH3OH, and NH3 condensed at T < 20 K on amorphous silicate smokes reveal that predominantly crystalline phase ice forms directly on deposit. Spectra of these molecules condensed on aluminum substrates at T < 20 K indicate that amorphous phase ice forms. On aluminum, crystalline phase H2O and CH3OH are formed by annealing amorphous deposits to 155 K and 130 K, respectively (or by direct deposit at these temperatures); crystalline NH3 is formed by direct deposit at 88 K. Silicate smokes are deposited onto aluminum substrates by evaporation of SiO solid or by combustion of SiH4, with O2 in flowing H-2 followed by vapor phase nucleation and growth. Silicate smokes which are oxygen-deficient may contain active surface sites which facilitate the amorphous-to-crystalline phase transition during condensation. Detailed experiments to understand the mechanism are currently in progress. The assumption that amorphous phase ice forms routinely on grains at T < 80 K is often used in models describing the volatile content of comets or in interpretations of interstellar cloud temperatures. This assumption needs to be reexamined in view of these results. C1 UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. RP MOORE, MH (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTROCHEM BRANCH,EXTRATERR PHYS LAB,CODE 691,GREENBELT,MD 20771, USA. RI Hudson, Reggie/E-2335-2012; Nuth, Joseph/E-7085-2012 NR 19 TC 13 Z9 13 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 1994 VL 428 IS 2 BP L81 EP L84 DI 10.1086/187398 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NQ753 UT WOS:A1994NQ75300010 ER PT J AU REUTER, DC SIROTA, JM AF REUTER, DC SIROTA, JM TI LINE-STRENGTH AND SELF-BROADENING COEFFICIENT OF THE PURE ROTATIONAL S(1) QUADRUPOLE LINE IN H-2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOLAR SYSTEM; LINE, PROFILES; MOLECULAR DATA ID SPECTROSCOPY AB The absolute intensity, S1, and self-broadening coefficient, gamma(L), for H-2 S0(1) pure rotational line at 17.0348 mum (587.032 cm-1) have been measured for the first time using a tunable diode laser spectrometer with a resolution of - 1 x 10(-3) cm-1. By fitting a Galatry line shape convolved with a 1 X 10(-3) cm-1 Gaussian instrument profile to absorption profiles, for H-2 pressures ranging from 0.34 to 1.30 atm, values of S1 = (7.0 +/- 0.4) x 10(-8) cm-2 atm-1 and gamma(L) = (1.73 +/- 0.12) x 10(-3) cm-1 atm-1 were obtained. RP REUTER, DC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,CODE 693,GREENBELT,MD 20771, USA. NR 17 TC 9 Z9 9 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 20 PY 1994 VL 428 IS 2 BP L77 EP L79 DI 10.1086/187397 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NQ753 UT WOS:A1994NQ75300009 ER PT J AU Gultepe, I Starr, DO AF Gultepe, I. Starr, D. O'C TI Microphysical and radiative development of a cirrus cloud during FIRE: implications for dynamical effects SO ATMOSPHERIC RESEARCH LA English DT Article AB Data for this study were collected over Minnesota on 19 October, 1986 during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) cirrus field campaign. Broadband radiometers mounted on the top and bottom of the NCAR King Air and Saberliner aircraft were used to measure irradiances. Constant altitude flight legs were flown at various altitudes within cirrus clouds. The data were averaged over the 60-km flight legs and used to calculate radiative heating rate profiles and cloud radiative properties over the resolved layers from 6 to 12 km. Adiabatic vertical velocity w (cooling rate) required to balance (compensate) the observed radiative heating rates was calculated. Values ranged from about 0.40 m s(-1) mid-cloud levels (8.2 km) to 0.05 m s(-1) at the 10 km level. In the absence of other processes, the pattern of radiative heating would have generated a unstable thermal stratification (partial derivative theta/partial derivative z < 0) at the 8.2 km level where a near neutrally stratified layer was observed within the cloud. Observations of the cirrus cloud ice particle size distribution and habit were used to define the cloud ice water content profile. Assuming steady state supersaturation (S) with respect to ice, the rate of adiabatic ascent required to maintain constant S against the effects of diffusional growth of the ice particles was calculated. The resulting vertical motions were found to be comparable to, but smaller than, those needed to compensate the effects of radiative heating. C1 [Gultepe, I.; Starr, D. O'C] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA. RP Gultepe, I (reprint author), NASA, Goddard Space Flight Ctr, Code 913, Greenbelt, MD 20771 USA. FU NASA Office of Space Science and Applications FX The authors wishes to thank to Dr. A. J. Heymsfield of the NCAR MMM section for providing and discussions on NCAR aircraft data set. This work was done while first author held a National Research Council Research Associateship at Climate and Radiation Branch of the NASA Goddard Space Flight Center in Greenbelt Maryland. This work was supported by the NASA Office of Space Science and Applications under the direction of Dr. John T. Suttles. NR 20 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0169-8095 EI 1873-2895 J9 ATMOS RES JI Atmos. Res. PD JUN 20 PY 1994 VL 34 IS 1-4 BP 43 EP 52 DI 10.1016/0169-8095(94)90080-9 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA V38LL UT WOS:000209344800003 ER PT J AU Wang, PH McCormick, MP Poole, LR Chu, WP Yue, GK Kent, GS Skeens, KM AF Wang, Pi-Huan McCormick, M. P. Poole, L. R. Chu, W. P. Yue, G. K. Kent, G. S. Skeens, K. M. TI Tropical high cloud characteristics derived from SAGE II extinction measurements SO ATMOSPHERIC RESEARCH LA English DT Article AB This work investigates the characteristics of tropical high clouds based on the 1989 Stratospheric Aerosol and Gas Experiment (SAGE II) particulate extinction measurements and the National Meteorological Center (NMC) temperature data. A discussion is also provided of the cloud measurement constraints of the SAGE II instrument, including optical limitation, sensitivity of the measurement to particle sizes, and uncertainty due to the spatial resolution of the sampling volume. Because of the viewing geometry of the solar occultation technique, the SAGE II instrument is very sensitive to thin cirrus clouds. The results of this study indicate that (1) the tropical high cloud data can be distinguished approximately from aerosol data by using the ratio of the extinction at 0.525 mu m to that at 1.02 mu m as an indicator, the 1989 cloud data being characterized by an extinction ratio less than 2.1; (2) the background aerosol size distribution in the tropical tropopause region is bimodal with the small mode extending even below a radius of 0.075 mu m and the large mode centered at a radius of 0.6 mu m; (3) SAGE II cloud extinction data reveal various degrees of wavelength dependency, which suggests specific progressive changes in particle size distribution during cloud development; and (4) aerosol nucleation and ice nucleation as well as coagulation growth of small particles are important processes in the tropical cirrus cloud evolution. The specific characteristics of the aerosol cloud interaction as manifested in the multiwavelength SAGE II high cloud extinctions in the tropical tropopause region can be useful information for model studies of the cirrus cloud evolution. C1 [Wang, Pi-Huan; Kent, G. S.; Skeens, K. M.] Sci & Technol Corp, Hampton, VA 23666 USA. [McCormick, M. P.; Poole, L. R.; Chu, W. P.; Yue, G. K.] NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. RP Wang, PH (reprint author), Sci & Technol Corp, 101 Res Dr, Hampton, VA 23666 USA. FU NASA [NAS1-19603] FX The authors would like to thank Dr. Peter V. Hobbs of the University of Washington; Drs. Bruce A. Wielicki, Bryan A. Baum and William B. Grant of NASA Langley Research Center for helpful discussions and Dr. P. Russell of NASA Ames Research Center for bringing the 1987 STEP Tropical Experiment results of Knollenberg et al. (1993) to our attention. P.-H. Wang, G.S. Kent and K.M. Skeens are supported by NASA contract NAS1-19603. NR 66 TC 55 Z9 55 U1 5 U2 5 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0169-8095 EI 1873-2895 J9 ATMOS RES JI Atmos. Res. PD JUN 20 PY 1994 VL 34 IS 1-4 BP 53 EP 83 DI 10.1016/0169-8095(94)90081-7 PG 31 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA V38LL UT WOS:000209344800004 ER PT J AU Platnick, S Twomey, S AF Platnick, S. Twomey, S. TI Remote sensing the susceptibility of cloud albedo to changes in drop concentration SO ATMOSPHERIC RESEARCH LA English DT Article AB The role of clouds in reflecting solar radiation to space and thereby reducing surface heating is of critical importance to climate. Combustion processes that produce greenhouse gases also increase cloud condensation nuclei (CCN) concentrations which in turn increase cloud drop concentrations and thereby cloud albedo. A calculation of cloud susceptibility, defined in this work as the increase in albedo resulting from the addition of one cloud drop per cubic centimeter (as cloud liquid water content remains constant), is made through satellite remote sensing of cloud drop radius and optical thickness. The remote technique uses spectral channels of the Advance Very High Resolution Radiometer (AVHRR) instrument on board the NOAA polar orbiting satellites. An approximation for the effect of the atmosphere on the signal received by the AVHRR is included in the analysis. Marine stratus clouds, as well as being important modifiers of climate, are cleaner than continental clouds an so likely to be of higher susceptibility. Analysis of several stratus scenes, including some containing ship tracks, supports this expectation. C1 [Platnick, S.] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. RP Platnick, S (reprint author), NASA, Ames Res Ctr, MS 245-4, Moffett Field, CA 94035 USA. OI Platnick, Steven/0000-0003-3964-3567 FU NSF through the Institute of Atmospheric Physics, Tucson, Arizona [ATM-8716637] FX This work was supported by NSF grant ATM-8716637 through the Institute of Atmospheric Physics, Tucson, Arizona. NR 29 TC 8 Z9 8 U1 0 U2 3 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0169-8095 EI 1873-2895 J9 ATMOS RES JI Atmos. Res. PD JUN 20 PY 1994 VL 34 IS 1-4 BP 85 EP 98 DI 10.1016/0169-8095(94)90082-5 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA V38LL UT WOS:000209344800005 ER PT J AU Winker, DM Vaughan, MA AF Winker, D. M. Vaughan, M. A. TI Vertical distribution of clouds over Hampton, Virginia observed by lidar under the ECLIPS and FIRE ETO programs SO ATMOSPHERIC RESEARCH LA English DT Article AB Intensive cloud lidar observations have been made by NASA Langley Research Center during the two observation phases of the ECLIPS project. Less intensive but longer term observations have been conducted as part of the FIRE extended time observation (ETO) program since 1987. We present a preliminary analysis of the vertical distribution of clouds based on these observations. A mean cirrus thickness of just under 1 km has been observed with a mean altitude of about 80% of the tropopause height. Based on the lidar data, cirrus coverage was estimated to be just under 20%, representing roughly 50% of all clouds studied. Cirrus was observed to have less seasonal variation than lower clouds. Mid-level clouds are found to occur primarily in association with frontal activity. C1 [Winker, D. M.] NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. [Vaughan, M. A.] Sci Applicat Int Corp, Hampton, VA 23666 USA. RP Winker, DM (reprint author), NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23681 USA. NR 14 TC 38 Z9 40 U1 1 U2 3 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0169-8095 EI 1873-2895 J9 ATMOS RES JI Atmos. Res. PD JUN 20 PY 1994 VL 34 IS 1-4 BP 117 EP 133 DI 10.1016/0169-8095(94)90084-1 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA V38LL UT WOS:000209344800007 ER PT J AU Schols, JL Weinman, JA AF Schols, J. L. Weinman, J. A. TI Retrieval of hydrometeor distributions over the ocean from airborne single-frequency radar and multi-frequency radiometric measurements SO ATMOSPHERIC RESEARCH LA English DT Article AB An algorithm was developed to retrieve vertical profiles of hydrometeor mass, and hydrometeor particle density and volumetric weighted diameters, derived from simultaneous airborne nadir directed 10 GHz radar measurements and 10, 19, 34 and 92 GHz radiometric measurements. The retrieval algorithm used a three layer model, i.e. frozen hydrometeors in the upper layer, melting hydrometeors below the freezing level in the middle layer, called the melting layer, and rain in the lower layer. In the lower layer, the algorithm used a modification of the Hitschfeld Bordan radar equation. A cloud physics model was used to describe the melting process of the hydrometeors in the melting layer. The dielectric constant of the frozen and melting hydrometeors was represented by a Maxwell-Garnet mixture of ice, air and water. In the upper layer, the frozen hydrometeors were assumed to have a particle size distribution (PSD) with the same small-size parameter, mu, as the rain drops in the lower layer. The PSD of the hydrometeors in the middle layer was determined by assuming continuity of vertical mass flux of the melting particles. Mie scattering computations and a finite cloud radiative transfer model were used in an optimizing procedure, based on Marquardt's non-linear least squares minimization, to match the model derived profile of the radar reflectivity factor, and brightness temperatures with measurements obtained on September 17, 1990 near the eye of typhoon Flo in the western Pacific. The algorithm yielded profiles of the mass density of the precipitation, the particle density and the volumetrically weighted diameter (VWD) of the PSD. The model was validated by comparing the measured profile of the 35 GHz effective radar reflectivity factor and the 192 GHz brightness temperature with their values computed using the hydrometeor parameters obtained from the retrieval algorithm. C1 [Schols, J. L.] Gen Sci Corp, Laurel, MD 20707 USA. [Weinman, J. A.] NASA, Goddard Space Flight Ctr, Microwave Sensors Branch, Greenbelt, MD 20771 USA. RP Schols, JL (reprint author), Gen Sci Corp, Laurel, MD 20707 USA. NR 18 TC 8 Z9 8 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0169-8095 EI 1873-2895 J9 ATMOS RES JI Atmos. Res. PD JUN 20 PY 1994 VL 34 IS 1-4 BP 329 EP 346 DI 10.1016/0169-8095(94)90101-5 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA V38LL UT WOS:000209344800024 ER PT J AU Hammer, PD Valero, FPJ Smith, WH AF Hammer, P. D. Valero, F. P. J. Smith, W. H. TI Spectral imaging of clouds using a digital array scanned interferometer SO ATMOSPHERIC RESEARCH LA English DT Article AB Spectral images of various cloud fields have been made from the ground using a prototype imaging interferometer. The instrument, called DASI (digital array scanned interferometer), is under development as an alternative technique for terrestrial remote sensing. Our paper describes the unusual characteristics of DASI's that make them promising candidates for both ground and aircraft based measurements of clouds. These characteristics include superior signal-to-noise potential, design simplicity and compactness. The prototype DASI had a wavelength sensitivity range of 4550-9090 cm(-1) (1.1-2.2 mu m), a spectral resolution of 300 cm(-1), a spatial field of view of 5 degrees, and 256 transverse spatial elements for each exposure frame with exposure rates up to 1 frame/s. Spectrally resolved images of cirrus and cumulus clouds over the San Francisco Bay area were obtained by multiple frame scanning over the field of view. The DASI measurements are compared with radiative transfer calculations using LOWTRAN-7. Modification of the LOWTRAN code was necessary so that high spectral resolution data for ice optical properties could be used. With these modifications, the agreement between measured and model results is good in some cases. However, quantitative interpretation of these preliminary measurements was not generally possible because of various sources of uncertainty. Finally, a discussion is given on the potential applications and science yields of DASI instruments in the framework of coordinated field missions such as project FIRE. Such applications include the use of ground and airborne based DASI's to retrieve microphysical properties of clouds and to investigate current problems in atmospheric radiation. C1 [Hammer, P. D.; Valero, F. P. J.] NASA, Ames Res Ctr, Earth Syst Sci Div, Moffett Field, CA 94035 USA. [Smith, W. H.] Washington Univ, Earth & Planetary Sci Dep, St Louis, MO 63130 USA. RP Hammer, PD (reprint author), NASA, Ames Res Ctr, Earth Syst Sci Div, Moffett Field, CA 94035 USA. FU NASA Ames Director's Discretionary Fund FX We wish to acknowledge the contributions of Allan Delamere, Mike Duncan and Dave Dorn at Ball Aerospace Corp., who provided us with the use of a dewar and data interface for the NICMOS MCT detector array, of Stephen Hipskind and Steven Gaines at NASA Ames Research Center for their efforts in acquiring GOES images to support our analyses and of David Peterson for providing us with laboratory and observing facilities. We are also grateful to Jim Miracle of Aerotech Corp. for the use of a computer controlled mirror system. This project was made possible with support from the NASA Ames Director's Discretionary Fund. NR 29 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE INC PI NEW YORK PA 360 PARK AVE SOUTH, NEW YORK, NY 10010-1710 USA SN 0169-8095 EI 1873-2895 J9 ATMOS RES JI Atmos. Res. PD JUN 20 PY 1994 VL 34 IS 1-4 BP 347 EP 366 DI 10.1016/0169-8095(94)90102-3 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA V38LL UT WOS:000209344800025 ER PT J AU ANDREAE, MO ANDERSON, BE BLAKE, DR BRADSHAW, JD COLLINS, JE GREGORY, GL SACHSE, GW SHIPHAM, MC AF ANDREAE, MO ANDERSON, BE BLAKE, DR BRADSHAW, JD COLLINS, JE GREGORY, GL SACHSE, GW SHIPHAM, MC TI INFLUENCE OF PLUMES FROM BIOMASS BURNING ON ATMOSPHERIC CHEMISTRY OVER THE EQUATORIAL AND TROPICAL SOUTH-ATLANTIC DURING CITE-3 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TROPOSPHERIC OZONE; CARBON-MONOXIDE; BOUNDARY-LAYER; AMAZON BASIN; DRY SEASON; EMISSIONS; AIRBORNE; BRAZIL; AFRICA; GASES AB During all eight flights conducted over the equatorial and tropical South Atlantic (27-degrees-35-degrees-W, 2-degrees-N-11-degrees-S; September 9-22, 1989) in the course of the Chemical Instrumentation Test and Evaluation (CITE 3) experiment, we observed haze layers with elevated concentrations of aerosols, O3, CO, and other trace gases related to biomass burning emissions. They occurred at altitudes between 1000 and 5200 m and were usually only some 100-300 m thick. These layers extended horizontally over several 100 km and were marked by the presence of visible brownish haze. These layers strongly influenced the chemical characteristics of the atmosphere over this remote oceanic region. Air mass trajectories indicate that these layers originate in the biomass burning regions of Africa and South America and typically have aged at least 10 days since the time of emission. In the haze layers, O3 and CO concentrations up to 90 and 210 ppb were observed, respectively. The two species were highly correlated. The ratio DELTAO3/DELTACO (DELTA, concentrations in plume minus background concentrations) is typically in the range 0.2-0.7, much higher than the ratios in the less aged plumes investigated previously in Amazonia. In most cases, aerosol (0.12-3 mum diameter) number concentrations were also elevated by up to 400 cm-3 in the layers; aerosol enrichments were also strongly correlated with elevated CO levels. Clear correlations between CO and NO(x), enrichments were not apparent due to the age of the plumes, in which most NO(x) would have already reacted away within 1-2 days. Only in some of the plumes could clear correlations between NO(y) and CO be identified; the absence of a general correlation between NO(y) and CO maybe due to instrumental limitations and to variable sinks for NO(y). The average enrichment of DELTANO(y)/DELTACO was quite high, consistent with the efficient production of ozone observed in the plumes. The chemical characteristics of the haze layers, together with remote sensing information and trajectory calculations, suggest that fire emissions (in Africa and/or South America) are the primary source of the haze layer components. C1 UNIV CALIF IRVINE, DEPT CHEM, IRVINE, CA 92717 USA. GEORGIA INST TECHNOL, SCH GEOPHYS SCI, ATLANTA, GA 30332 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. RP ANDREAE, MO (reprint author), MAX PLANCK INST CHEM, DEPT BIOGEOCHEM, POB 3060, D-55020 MAINZ, GERMANY. RI Andreae, Meinrat/B-1068-2008 OI Andreae, Meinrat/0000-0003-1968-7925 NR 60 TC 115 Z9 116 U1 2 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 20 PY 1994 VL 99 IS D6 BP 12793 EP 12808 DI 10.1029/94JD00263 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NT337 UT WOS:A1994NT33700002 ER PT J AU NOVELLI, PC COLLINS, JE MYERS, RC SACHSE, GW SCHEEL, HE AF NOVELLI, PC COLLINS, JE MYERS, RC SACHSE, GW SCHEEL, HE TI REEVALUATION OF THE NOAA-CMDL CARBON-MONOXIDE REFERENCE SCALE AND COMPARISONS WITH CO REFERENCE GASES AT NASA-LANGLEY AND THE FRAUNHOFER-INSTITUT SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID METHANE; TRENDS; CH4 AB The carbon monoxide (CO) reference scale created by the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL) is used to quantify measurements of CO in the atmosphere, calibrate standards of other laboratories and to otherwise provide reference gases to the community measuring atmospheric CO. This reference scale was created based upon a set of primary standards prepared by gravimetric methods at CMDL and has been propagated to a set of working standards. In this paper we compare CO mixing ratios assigned to the working standards by three approaches: (1) calibration against the original gravimetric standards, (2) calibration using only working standards as the reference gas, and (3) calibration against three new gravimetric standards prepared at CMDL. The agreement between these values was typically better than 1%. The calibration histories of CMDL working standards are reviewed with respect to expected rates of CO change in the atmosphere. Using a Monte Carlo approach to simulate the effect of drifting standards on calculated mixing ratios, we conclude that the error solely associated with the maintenance of standards will limit the ability to detect small CO changes in the atmosphere. We also report results of intercalibration experiments conducted between CMDL and the Diode Laser Sensor Group (DACOM) at the NASA Langley Research Center (Hampton, Virginia), and CMDL and the Fraunhofer-Institut (Garmisch-Partenkirchen, Germany). Each laboratory calibrated several working standards for CO using their reference gases, and these results were compared to calibrations conducted by CMDL. The intercomparison of eight standards (CO concentrations between approximately 100 and approximately 165 ppb) by CMDL and NASA agreed to better than +/-2%. The calibration of six standards (CO concentrations between approximately 50 and approximately 210 ppb) by CMDL and the Fraunhofer-Institut agreed to within +/- 2% for four standards, and to within +/- 5% for all six standards. C1 NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. SCI & TECHNOL CORP, HAMPTON, VA 23666 USA. FRAUNHOFER INST ATMOSPHARISCHE UMWELTFORSCHUNG, D-82457 GARMISCH PARTENKIRCHEN, GERMANY. RP NOVELLI, PC (reprint author), UNIV COLORADO, COOPERAT INST RES ENVIRONM SCI, CAMPUS BOX 449, BOULDER, CO 80309 USA. RI Garmisch-Pa, Ifu/H-9902-2014 NR 12 TC 38 Z9 38 U1 1 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 20 PY 1994 VL 99 IS D6 BP 12833 EP 12839 DI 10.1029/94JD00314 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NT337 UT WOS:A1994NT33700005 ER PT J AU PUESCHEL, RF RUSSELL, PB ALLEN, DA FERRY, GV SNETSINGER, KG LIVINGSTON, JM VERMA, S AF PUESCHEL, RF RUSSELL, PB ALLEN, DA FERRY, GV SNETSINGER, KG LIVINGSTON, JM VERMA, S TI PHYSICAL AND OPTICAL-PROPERTIES OF THE PINATUBO VOLCANIC AEROSOL - AIRCRAFT OBSERVATIONS WITH IMPACTORS AND A SUN-TRACKING PHOTOMETER SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ERUPTION; SULFATE AB As determined in situ by impactor samplers flown on an ER-2 at 16.5- to 20.7-km pressure altitude and on a DC-8 at 9.5- to 12.6-km pressure altitudes, the 1991 Pinatubo volcanic eruption increased the particle surface area of stratospheric aerosols up to 50-fold and the particle volume up to 2 orders of magnitude. Particle composition was typical of a sulfuric acid-water mixture at ER-2 altitudes. Ash particles coated with sulfuric acid comprised a significant fraction of aerosol at DC-8 altitudes. Mie-computed light extinction increased up to 20-fold at midvisible and > 100-fold at near-IR wavelengths. The optical thickness measured through the aerosol layer by an autotracking Sun photometer aboard a DC-8 aircraft at 10.7- to 11.3-km pressure altitudes shows a spectral shape that is similar to the Mie-calculated spectral extinction at ER-2 altitudes. Surface area distributions calculated by inversion of spectral optical depth measurements show characteristics that are similar to the mean surface area distribution resulting from 35 in situ measurements. C1 SRI INT, MENLO PK, CA 94024 USA. TMA NORCAL, RICHMOND, CA 94804 USA. RP PUESCHEL, RF (reprint author), NASA, AMES RES CTR, MAIL CODE SGP 245-4, MOFFETT FIELD, CA 94035 USA. NR 12 TC 86 Z9 86 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 JUN 20 PY 1994 VL 99 IS D6 BP 12915 EP 12922 DI 10.1029/94JD00621 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NT337 UT WOS:A1994NT33700012 ER PT J AU POOLE, LR PITTS, MC AF POOLE, LR PITTS, MC TI POLAR STRATOSPHERIC CLOUD CLIMATOLOGY BASED ON STRATOSPHERIC AEROSOL MEASUREMENT-II OBSERVATIONS FROM 1978 TO 1989 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SAM-II; NITRIC-ACID; ANTARCTIC STRATOSPHERE; OZONE HOLE; WINTER; TEMPERATURES; SATELLITE; WATER AB The probability of polar stratospheric cloud (PSC) occurrence in the Antarctic and Arctic has been estimated using Stratospheric Aerosol Measurement (SAM) II aerosol extinction data from 1978 to 1989. Antarctic PSCs are typically observed by SAM II from mid-May to early November, with a maximum zonal average probability of about 0.6 at 18-20 km in August. The typical Arctic PSC season extends only from late November to early March, with a peak zonal average probability of about 0.1 in early February at 20-22 km. There is considerable year-to-year variability in Arctic PSC sightings because of changes in the dynamics of the northern polar vortex. Year-to-year variability in Antarctic sightings is most prominent in the number of late season clouds. Maximum PSC sighting probabilities in both polar regions occur in the region from 90-degrees-W through the Greenwich meridian to 90-degrees-E, where temperatures are coldest on average. Arctic sighting probabilities approach zero outside this region, but clouds have been sighted in the Antarctic at all longitudes during most months. Inferred PSC formation temperatures remain constant throughout the Arctic winter and are similar to those in early Antarctic winter. PSC formation temperatures in the Antarctic drop markedly in the 15 to 20-km region by September, a pattern consistent with the irreversible loss of HNO3 and H2O vapor in sedimenting PSC particles. C1 SCI APPLICAT INT CORP, HAMPTON, VA 23666 USA. RP POOLE, LR (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, MAIL CODE 475, HAMPTON, VA 23681 USA. NR 23 TC 101 Z9 101 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD JUN 20 PY 1994 VL 99 IS D6 BP 13083 EP 13089 DI 10.1029/94JD00411 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NT337 UT WOS:A1994NT33700022 ER PT J AU KELLER, LP MCKAY, DS AF KELLER, LP MCKAY, DS TI VAPOR DEPOSITS IN THE LUNAR REGOLITH - REPLY SO SCIENCE LA English DT Note C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP KELLER, LP (reprint author), MVA INC,5500 OAKBROOK PKWY,SUITW 200,NORCROSS,GA 30093, USA. NR 3 TC 6 Z9 7 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD JUN 17 PY 1994 VL 264 IS 5166 BP 1780 EP 1780 DI 10.1126/science.264.5166.1780 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NR600 UT WOS:A1994NR60000050 PM 17839915 ER PT J AU SHORE, SN STARRFIELD, S GONZALEZRIESTRA, R HAUSCHILDT, PH SONNEBORN, G AF SHORE, SN STARRFIELD, S GONZALEZRIESTRA, R HAUSCHILDT, PH SONNEBORN, G TI DUST FORMATION IN NOVA-CASSIOPEIAE 1993 SEEN BY ULTRAVIOLET-ABSORPTION SO NATURE LA English DT Article AB THE clouds of gas in interstellar space also contain grains of dust, whose properties and origins have been the focus of debate for decades. Some dust formation has been assumed to take place in novae explosions(1-5), as was first implied by the observation of a steep decrease in the amount of light emitted by the nova(1,2) DQ Herculis 1934 about 100 days after outburst, presumed to be due to extinction by dust. Here we report observations from the International Ultraviolet Explorer satellite which show directly the onset of dust formation in Nova Cassiopeiae 1993, a classical nova of the same type as DQ Her 1934. The dust formed very quickly-about 70 days after the nova explosion despite the initially high temperature of the ejecta. Our results suggest that high-energy photons are absorbed efficiently by the gas in the ejecta, lowering the temperature in the gas while it is still dense, and thereby allowing molecules to form and then to condense into dust. C1 ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. EUROPEAN SPACE AGCY,ESTEC,DEPT SPACE SCI,DIV ASTROPHYS,VILLAFRANCA,SPAIN. EUROPEAN SPACE AGCY,INT ULTRAVIOLET EXPLORER,VILLAFRANCA,SPAIN. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP SHORE, SN (reprint author), INDIANA UNIV,DEPT PHYS & ASTRON,1700 MISHAWAKA AVE,S BEND,IN 46634, USA. RI Sonneborn, George/D-5255-2012 NR 22 TC 40 Z9 40 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 JUN 16 PY 1994 VL 369 IS 6481 BP 539 EP 541 DI 10.1038/369539a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA NR294 UT WOS:A1994NR29400041 ER PT J AU WOO, R GAZIS, PR AF WOO, R GAZIS, PR TI MASS FLUX IN THE ECLIPTIC-PLANE AND NEAR THE SUN DEDUCED FROM DOPPLER SCINTILLATION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND; SMM OBSERVATIONS; PIONEER; DEPENDENCE; EJECTIONS AB During the late declining phase of the solar cycle, the tilt of the solar magnetic dipole with respect to the Sun's rotation axis leads to large-scale organization of the solar wind, such that alternating regions of high- and low-speed solar wind are observed in the ecliptic plane. In this paper, we use Doppler scintillation measurements to investigate mass flux of these two types of solar wind in the ecliptic plane and inside 0.3 AU, where in situ measurements have not been possible. To the extent that Doppler scintillation reflects mass flux, we find that mass flux in high-speed streams: (1) is lower (by a factor of approximately 2.2) than the mass flux of the average solar wind in the heliocentric distance range of 0.3-0.5 AU, (2) is lower still (by as much as a factor of about 4) than the mass flux of the slow solar wind associated with the streamer belt, and (3) appears to grow with heliocentric distance. These Doppler scintillation results are consistent with the equator to pole decrease in mass flux observed in earlier spectral broadening measurements, and with trends and differences between high- and low-speed solar wind observed by in situ measurements in the range of 0.3-1.0 AU. The mass flux results suggest that the solar wind flow in high-speed streams is convergent towards the ecliptic near the Sun, becoming less convergent and approaching radial with increasing heliocentric distance beyond 0.3 AU. The variability of mass flux observed within equatorial and polar high-speed streams close to the Sun is strikingly low. This low variability implies that, as Ulysses currently ascends to higher latitudes and spends more time in the south polar high-speed stream after crossing the heliospheric current sheet, it can expect to observe a marked decrease in variations of both mass flux and solar wind speed, a trend that appears to have started already. C1 NASA,AMES RES CTR,SAN JOSE STATE UNIV FDN,MOFFETT FIELD,CA 94035. RP WOO, R (reprint author), JET PROP LAB,MS 238-737,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 22 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1994 VL 21 IS 12 BP 1101 EP 1104 DI 10.1029/94GL01064 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NT217 UT WOS:A1994NT21700001 ER PT J AU PHILLIPS, JL BALOGH, A BAME, SJ GOLDSTEIN, BE GOSLING, JT HOEKSEMA, JT MCCOMAS, DJ NEUGEBAUER, M SHEELEY, NR WANG, YM AF PHILLIPS, JL BALOGH, A BAME, SJ GOLDSTEIN, BE GOSLING, JT HOEKSEMA, JT MCCOMAS, DJ NEUGEBAUER, M SHEELEY, NR WANG, YM TI ULYSSES AT 50-DEGREES SOUTH - CONSTANT IMMERSION IN THE HIGH-SPEED SOLAR-WIND SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HELIOSPHERIC CURRENT SHEET; SECTOR STRUCTURE; EVOLUTION; CYCLE AB We present speed observations from the Ulysses solar wind plasma experiment through 50-degrees south latitude. The pronounced speed modulation arising from solar rotation and the tilt of the heliomagnetic current sheet has nearly disappeared. Ulysses is now observing wind speeds in the 700 to 800 km s-1 range, with a magnetic polarity indicating an origin in the large south polar coronal hole. The strong compressions, rarefactions, and shock waves previously seen have weakened or disappeared. Occasional coronal mass ejections characterized by low plasma density caused by radial expansion have been observed. The coronal configuration was simple and stable in 1993, indicating that the observed solar wind changes were caused by increasing spacecraft latitude. Trends in prevailing speed with increasing latitude support previous findings. A decrease in peak speed southward of 40-degrees latitude may indicate that the fastest solar wind comes from the equatorial extensions of the polar coronal holes. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. JET PROP LAB,PASADENA,CA 91109. STANFORD UNIV,ERL 322 CSSA,STANFORD,CA 94305. USN,RES LAB,CODE 7672,WASHINGTON,DC 20375. RP PHILLIPS, JL (reprint author), LOS ALAMOS NATL LAB,MS D466,LOS ALAMOS,NM 87545, USA. NR 16 TC 98 Z9 98 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1994 VL 21 IS 12 BP 1105 EP 1108 DI 10.1029/94GL01065 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NT217 UT WOS:A1994NT21700002 ER PT J AU GOSLING, JT BAME, SJ MCCOMAS, DJ PHILLIPS, JL GOLDSTEIN, BE NEUGEBAUER, M AF GOSLING, JT BAME, SJ MCCOMAS, DJ PHILLIPS, JL GOLDSTEIN, BE NEUGEBAUER, M TI THE SPEEDS OF CORONAL MASS EJECTIONS IN THE SOLAR-WIND AT MID HELIOGRAPHIC LATITUDES - ULYSSES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ELECTRON EVENTS AB Six CMEs have been detected in the Ulysses plasma observations poleward of S31-degrees. The most striking aspect of these mid-latitude CMEs was their high speeds; the overall average speed of these CMEs was -740 km s-1, which was comparable to that of the rest of the solar wind at these latitudes. This average CME speed is much higher than average CME speeds observed in the solar wind in the ecliptic or in the corona close to the Sun. The evidence indicates that the CMEs were not pushed up to high speeds in interplanetary space by interaction with trailing high-speed plasma. Rather, they simply seem to have received the same basic acceleration as the rest of the solar wind at these mid-latitudes. Our results suggest that the basic acceleration process for many CMEs at all latitudes is essentially the same as for the normal solar wind. Frequently most of this acceleration must occur well beyond 6 solar radii from Sun center. C1 JET PROP LAB,PASADENA,CA 91109. RP GOSLING, JT (reprint author), LOS ALAMOS NATL LAB,MS D466,LOS ALAMOS,NM 87545, USA. NR 18 TC 31 Z9 31 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1994 VL 21 IS 12 BP 1109 EP 1112 DI 10.1029/94GL01068 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NT217 UT WOS:A1994NT21700003 ER PT J AU SANDERSON, TR MARSDEN, RG WENZEL, KP BALOGH, A FORSYTH, RJ GOLDSTEIN, BE AF SANDERSON, TR MARSDEN, RG WENZEL, KP BALOGH, A FORSYTH, RJ GOLDSTEIN, BE TI ULYSSES HIGH-LATITUDE OBSERVATIONS OF IONS ACCELERATED BY CO-ROTATING INTERACTION REGIONS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SECTOR STRUCTURE; INTERPLANETARY AB We present observations of energetic ions (E approximately 1 MeV) from the Ulysses spacecraft during its first pass from the ecliptic plane to the southern high-latitude regions of the heliosphere. At latitudes less than approximately 13(O)S Ulysses was completely immersed in the heliomagnetic streamer belt, and observed a approximately 1 MeV proton intensity which showed little evidence of a periodic structure. Between approximately 13(O)S and approximately 29(O)S Ulysses observed one dominant recurrent co-rotating interaction region, its reverse shocks being mainly responsible for accelerating the approximately 1 MeV protons. At approximately 29(O)S the spacecraft left this region and entered the solar wind flow from the polar coronal hole. From approximately 29O up to approximately 45(O)S, reverse shocks from this and other interaction regions were still being observed. Accelerated energetic ions, with proton-to-alpha ratio signatures consistent with having been accelerated by the reverse shocks of these co-rotating interacting regions, were still being observed up to latitudes of approximately 50(O)S. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. JET PROP LAB,PASADENA,CA 91109. RP SANDERSON, TR (reprint author), ESTEC,ESA,DEPT SPACE SCI,NOORDWIJK,NETHERLANDS. NR 10 TC 40 Z9 40 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1994 VL 21 IS 12 BP 1113 EP 1116 DI 10.1029/94GL01062 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NT217 UT WOS:A1994NT21700004 ER PT J AU GOODMAN, J SNETSINGER, KG PUESCHEL, RF FERRY, GV VERMA, S AF GOODMAN, J SNETSINGER, KG PUESCHEL, RF FERRY, GV VERMA, S TI EVOLUTION OF PINATUBO AEROSOL NEAR 19 KM ALTITUDE OVER WESTERN NORTH-AMERICA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EL-CHICHON; STRATOSPHERIC AEROSOLS; ERUPTION; CLOUDS; LIDAR; JUNE AB Stratospheric aerosols, collected near 19 km altitude on wire impactors over western North America from August 20, 1991 to May 11, 1993, show strong influence of the June 1991 Mt. Pinatubo eruption. Lognormal size distributions are bimodal; each of the mode radii increases and reaches maximum value at about 15 months after eruption. The second (large particle) mode becomes well developed then, and about 40% of the droplets are larger than 0.4 mum radius. The eruption of Mt. Spurr (Alaska) may also have contributed to this. Sulfate mass loading decays exponentially (e-folding 216 days), similar to El Chichon. Silicates are present in samples only immediately after eruption, Two years after eruption, sulfate mass loading is about 0.4 mug/m3, about an order of magnitude higher than background pre-volcanic values. Aerosol size distributions are still bimodal with a very well-defined large droplet mode. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. TMA NORCAL INC,RICHMOND,CA. RP GOODMAN, J (reprint author), SAN JOSE STATE UNIV,DEPT METEOROL,1 WASHINGTON SQ,SAN JOSE,CA 95192, USA. NR 25 TC 50 Z9 50 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1994 VL 21 IS 12 BP 1129 EP 1132 DI 10.1029/94GL00696 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NT217 UT WOS:A1994NT21700008 ER PT J AU BHATT, PP REMSBERG, EE SCHMIDLIN, FJ GORDLEY, LL BURTON, JC AF BHATT, PP REMSBERG, EE SCHMIDLIN, FJ GORDLEY, LL BURTON, JC TI ON THE DETERMINATION OF BIASES IN SATELLITE-DERIVED TEMPERATURE PROFILES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID LIMB INFRARED MONITOR; STRATOSPHERE AB Comparisons are presented between Nimbus 7 LIMS mapped temperatures and both Datasonde and sphere in situ rocketsonde temperature measurements. With this approach up to 666 LIMS/Datasonde pairs were obtained for various pressure levels to look for small biases in LIMS temperatures as a function of altitude, latitude and season. Between 10-1 hPa LIMS and Datasonde agree everywhere to better than +/-2 K with the exception of a warm bias of about 3 K at 2 hPa at high latitudes. However, LIMS is colder than the Datasonde by about 4 K at 0.4 hPa and by about 8-10 K at 0.1 hPa. When compared with the more accurate sphere temperatures the bias at 0.1 hPa is reduced by nearly one-half These results indicate that the LIMS zonal mean constituent profiles are nearly free of temperature bias, except perhaps at 0.1 hPa. C1 LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681. NASA,GODDARD SPACE FLIGHT CTR,WALLOPS FLIGHT FACIL,GREENBELT,MD 20771. GATS,HAMPTON,VA 23666. RP BHATT, PP (reprint author), SAIC,1 ENTERPRISE PLAZA,HAMPTON,VA 23666, USA. NR 9 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 15 PY 1994 VL 21 IS 12 BP 1145 EP 1148 DI 10.1029/94GL01125 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NT217 UT WOS:A1994NT21700012 ER PT J AU LAU, KM SUI, CH CHOU, MD TAO, WK AF LAU, KM SUI, CH CHOU, MD TAO, WK TI AN INQUIRY INTO THE CIRRUS-CLOUD THERMOSTAT EFFECT FOR TROPICAL SEA-SURFACE TEMPERATURE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID WARM-POOL; CLIMATE; CONVECTION AB In this paper, we investigate the relative importance of local vs remote control on cloud radiative forcing using a cumulus ensemble model. It is found that cloud and surface radiation forcings are much more sensitive to the mean vertical motion associated with large scale tropical circulation than to the local SST. When the local SST is increased with the mean vertical motion held constant, increased surface latent and sensible heat flux associated with enhanced moisture recycling is found to be the primary mechanism for cooling the ocean surface. Large changes in surface shortwave fluxes are related to changes in cloudiness induced by changes in the large scale circulation. These results are consistent with a number of earlier empirical studies, which raised concerns regarding the validity of the cirrus-thermostat hypothesis (Ramanathan and Collins, 1991). It is argued that for a better understanding of cloud feedback, both local and remote controls need to be considered and that a cumulus ensemble model is a powerful tool that should be explored for such purpose. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP LAU, KM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. OI SUI, CHUNG-HSIUNG/0000-0003-2842-5660 NR 16 TC 62 Z9 62 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD JUN 15 PY 1994 VL 21 IS 12 BP 1157 EP 1160 DI 10.1029/94GL00222 PG 4 WC Geosciences, Multidisciplinary SC Geology GA NT217 UT WOS:A1994NT21700015 ER PT J AU LAU, KM SUI, CH CHOU, MD TAO, WK AF LAU, KM SUI, CH CHOU, MD TAO, WK TI AN INQUIRY INTO THE CIRRUS-CLOUD THERMOSTAT EFFECT FOR TROPICAL SEA-SURFACE TEMPERATURE - REPLY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Letter C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP LAU, KM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 4 TC 1 Z9 1 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 JUN 15 PY 1994 VL 21 IS 12 BP 1187 EP 1188 DI 10.1029/94GL00984 PG 2 WC Geosciences, Multidisciplinary SC Geology GA NT217 UT WOS:A1994NT21700023 ER PT J AU ARNOLD, SM SALEEB, AF TAN, HQ ZANG, Y AF ARNOLD, SM SALEEB, AF TAN, HQ ZANG, Y TI EXPLICIT ROBUST SCHEMES FOR IMPLEMENTATION OF A CLASS OF PRINCIPAL VALUE-BASED CONSTITUTIVE MODELS - SYMBOLIC AND NUMERIC IMPLEMENTATION SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING LA English DT Article ID FINITE AB The issue of developing effective and robust schemes to implement a class of the Ogden-type hyperelastic constitutive models is addressed. To this end, special purpose functions (running under MACSYMA) are developed for the symbolic derivation, evaluation, and automatic FORTRAN code generation of explicit expressions for the corresponding stress function and material tangent stiffness tensors. These explicit forms are valid over the entire deformation range, since the singularities resulting from repeated principal-stretch values have been theorectically removed. The required computational algorithms are outlined, and the resulting FORTRAN computer code is presented, C1 UNIV AKRON,AKRON,OH 44325. RP ARNOLD, SM (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 19 TC 4 Z9 4 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0029-5981 J9 INT J NUMER METH ENG JI Int. J. Numer. Methods Eng. PD JUN 15 PY 1994 VL 37 IS 11 BP 1931 EP 1944 DI 10.1002/nme.1620371110 PG 14 WC Engineering, Multidisciplinary; Mathematics, Interdisciplinary Applications SC Engineering; Mathematics GA NL692 UT WOS:A1994NL69200009 ER PT J AU NEUDECK, P KANG, S PETIT, J TABIBAZAR, M AF NEUDECK, P KANG, S PETIT, J TABIBAZAR, M TI MEASUREMENT OF N-TYPE DRY THERMALLY OXIDIZED 6H-SIC METAL-OXIDE-SEMICONDUCTOR DIODES BY QUASI-STATIC AND HIGH-FREQUENCY CAPACITANCE VERSUS VOLTAGE AND CAPACITANCE TRANSIENT TECHNIQUES SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID 6H SILICON-CARBIDE; ELECTRICAL-PROPERTIES; SPECTROSCOPY; OXIDATION AB Dry-oxidized n-type 6H-SiC metal-oxide-semiconductor capacitors are investigated using quasistatic capacitance versus voltage (C-V), high-frequency C-V, and pulsed high-frequency capacitance transient (C-t) analysis over the temperature range from 297 to 573 K. The quasistatic C- V characteristics presented are the first reported for 6H-SiC MOS capacitors, and exhibit startling nonidealities due to nonequilibrium conditions that arise from the fact that the recombination/generation process in 6H-SiC is extraordinarily slow even at the highest measurement temperature employed. The high-frequency dark C-V characteristics all showed deep depletion with no observable hysteresis. The recovery of the high-frequency capacitance from deep depletion to inversion was used to characterize the minority-carrier generation process as a function of temperature. Zerbst analysis conducted on the resulting C-t transients, which were longer than 1000 s at 573 K, showed a generation lifetime thermal activation energy of 0.49 eV. C1 CASE WESTERN RESERVE UNIV,DEPT MAT ENGN & SCI,CLEVELAND,OH 44106. NYMA INC,LERC GRP,BROOKPARK,OH 44142. HARVARD UNIV,DEPT CHEM,CAMBRIDGE,MA 02138. RP NEUDECK, P (reprint author), NASA,LEWIS RES CTR,MS 77-1,CLEVELAND,OH 44135, USA. NR 23 TC 39 Z9 39 U1 0 U2 3 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD JUN 15 PY 1994 VL 75 IS 12 BP 7949 EP 7953 DI 10.1063/1.356583 PG 5 WC Physics, Applied SC Physics GA NQ986 UT WOS:A1994NQ98600048 ER PT J AU WEBER, M REUTER, DC SIROTA, JM BLASS, WE HILLMAN, JJ AF WEBER, M REUTER, DC SIROTA, JM BLASS, WE HILLMAN, JJ TI FOURIER-TRANSFORM INFRARED AND TUNABLE DIODE-LASER SPECTER OF THE (CCH6)-C-13-C-12 NU(12) TORSION-VIBRATIAN-ROTATION BAND - FREQUENCIES, INTENSITIES, AND BARRIERS TO INTERNAL-ROTATION SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID NU-9 BAND; ETHANE; PARAMETERS; SPECTROSCOPY; CH3CH3; STATE AB High resolution spectra in the 12,2 mu m region of the upsilon(12) fundamental of the minor isotopomer (CCH6)-C-13-C-12 have been recorded. Torsional coriolis interaction of the excited upsilon(12)=1 state with the close lying excited torsional upsilon(6)=3 State leads to observed splittings of up to several tenths of cm(-1) in upsilon(12) near the crossing region at K Delta K=-18. Torsional splittings measured with a high resolution tunable diode spectrometer (TDL) and more than 2200 lines measured with a Fourier transform spectrometer (FTS) have been analyzed in a global nonlinear least squares fit to a symmetric top Hamiltonian. The standard deviation of the overall fit is 5.5X10(-4) cm(-1). From 17 intensity measurements of individual lines, a square dipole moment of R(upsilon)(2)=7.45(29)X10(-4) D-2 has been derived for the upsilon(12) fundamental. RP WEBER, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,MAIL CODE 690,GREENBELT,MD 20771, USA. RI Blass, William/A-2792-2008; Weber, Mark/F-1409-2011 OI Weber, Mark/0000-0001-8217-5450 NR 27 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 JUN 15 PY 1994 VL 100 IS 12 BP 8681 EP 8688 DI 10.1063/1.466723 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NR284 UT WOS:A1994NR28400013 ER PT J AU MA, Q TIPPING, RH AF MA, Q TIPPING, RH TI EXTENSION OF THE QUASI-STATIC FAR-WING LINE-SHAPE THEORY TO MULTICOMPONENT ANISOTROPIC POTENTIALS SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID INFRARED-ABSORPTION SPECTRA; WATER CONTINUUM ABSORPTION; STATISTICAL-THEORY; REGION; BANDS AB The formalism developed previously for the calculation of the far-wing line shape function and the corresponding absorption coefficient using a single-component anisotropic interaction term and the binary collision and quasistatic approximations is generalized to multicomponent anisotropic potential functions. Explicit expressions are presented for several common cases, including the long-range dipole-dipole plus dipole-quadrupole interaction and a linear molecule interacting with a perturber atom. After determining the multicomponent functional representation for the interaction between CO2 and Ar from previous published data, we calculate the theoretical line shape function and the corresponding absorption due to the nu(3) band of CO2 in the frequency region 2400-2580 cm(-1) and compare our results with previous calculations carried out using a single-component anisotropic interaction, and with the results obtained assuming Lorentzian line shapes. The principal uncertainties in the present results, possible refinements of the theoretical formalism, and the applicability to other systems are discussed briefly. C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. UNIV ALABAMA,DEPT PHYS & ASTRON,TUSCALOOSA,AL 35487. RP MA, Q (reprint author), COLUMBIA UNIV,DEPT APPL PHYS,NEW YORK,NY 10025, USA. NR 18 TC 9 Z9 9 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD JUN 15 PY 1994 VL 100 IS 12 BP 8720 EP 8736 DI 10.1063/1.466727 PG 17 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA NR284 UT WOS:A1994NR28400018 ER PT J AU CAVALIERI, DJ AF CAVALIERI, DJ TI A MICROWAVE TECHNIQUE FOR MAPPING THIN SEA-ICE SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article; Proceedings Paper CT Miniconference on Observation and Modeling of North Atlantic Deep Water Formation and its Variability CY NOV, 1991 CL COLUMBIA UNIV, LAMONT DOHERTY EARTH OBSERV, PALISADES, NY HO COLUMBIA UNIV, LAMONT DOHERTY EARTH OBSERV AB A technique is presented for mapping the distribution of new, young and first-year sea ice in seasonal sea ice zones that utilizes microwave spectral and polarization information from the Defense Meteorological Satellite Program Special Sensor Microwave/Imager. The motivation for this work stems from the need for accurate estimates of open water and thin ice within the Arctic ice pack. The technique utilizes the microwave polarization and spectral characteristics of these three ice types through two microwave radiance ratios: the 19.4 GHz polarization and the spectral gradient ratio, which is a measure of the spectral difference between the 19.4-GHz and the 37.0-GHz vertically polarized radiance components. The combined use of the spectral gradient ratio and polarization reduces the low ice concentration bias generally associated with the presence of thin ice types. The microwave polarization, which is sensitive to changes in ice thickness and ice surface characteristics, is used to classify new, young, and first-year ice types. The polarization varies from about 0.3 for calm ice-free water, to about 0.15 for new ice, and to 0.03 for thick first-year ice. On the basis of this parameterization, improved sea ice concentration maps and maps of new, young and first-year ice type distributions are derived. Examples from the Bering Sea are presented and comparisons are made with analyzed NOAA AVHRR imagery. RP CAVALIERI, DJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,CODE 971,GREENBELT,MD 20771, USA. NR 24 TC 88 Z9 91 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 1994 VL 99 IS C6 BP 12561 EP 12572 DI 10.1029/94JC00707 PG 12 WC Oceanography SC Oceanography GA NT504 UT WOS:A1994NT50400017 ER PT J AU GLAZMAN, RE GREYSUKH, A ZLOTNICKI, V AF GLAZMAN, RE GREYSUKH, A ZLOTNICKI, V TI EVALUATING MODELS OF SEA-STATE BIAS IN SATELLITE ALTIMETRY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article; Proceedings Paper CT Miniconference on Observation and Modeling of North Atlantic Deep Water Formation and its Variability CY NOV, 1991 CL COLUMBIA UNIV, LAMONT DOHERTY EARTH OBSERV, PALISADES, NY HO COLUMBIA UNIV, LAMONT DOHERTY EARTH OBSERV ID ELECTROMAGNETIC BIAS; RADAR ALTIMETRY; GEOMETRY; FIELD; MSL AB Investigations of the sea state bias (SSB) in altimeter measurements of sea surface height (SSH) have been reported by many authors based on aircraft, sea tower, and satellite-borne observations. These investigations have resulted in several proposed algorithms of the form SSB = epsilonH, where H is the significant wave height (SWH) and epsilon is a nondimensional function of wind speed U and SWH available from altimeter measurements. In the present work, on the basis of the full set of Geosat and an 8-month set of TOPEX altimeter measurements, all known algorithms are examined and a conclusion is reached that the altimeter-based U and SWH are insufficient to estimate the SSB correction with uniformly high accuracy. As a criterion of model performance we employ the value (called here the accuracy gain) by which the total variance of temporal changes in surface elevation is reduced owing to an SSB correction. This quantity is estimated for global data as well as for several selected regions of sufficiently large size. The linear geophysical model function (GMF) of the form epsilon = a0 + a1U is shown to yield an improvement over the simplest GMF with a constant epsilon. A three-parameter linear form epsilon = a0 + a1U + a2H produces somewhat better results. A two-parameter, physically based GMF relating epsilon to the pseudo wave age xi (where xi is estimated using altimeter wind and SWH) yields even higher accuracy, while the three-parameter GMF of form epsilon = a0 + a1U + a2U2 yields the highest accuracy gain for global data sets. However, in terms of the SSB values, the difference between different GMFs is marginal, and the accuracy gain (as a measure of the SSB models performance) is shown to have serious deficiencies. We find that for all the SSB models, globally tuned empirical parameters often yield unacceptably poor results for certain regions in which local physical conditions differ from the global average: when the globally tuned GMFs are applied to such regions, the SSB-related error in SSH may well exceed 5 cm. RP GLAZMAN, RE (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 33 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD JUN 15 PY 1994 VL 99 IS C6 BP 12581 EP 12591 DI 10.1029/94JC00478 PG 11 WC Oceanography SC Oceanography GA NT504 UT WOS:A1994NT50400019 ER PT J AU LIU, WT ZHANG, AZ BISHOP, JKB AF LIU, WT ZHANG, AZ BISHOP, JKB TI EVAPORATION AND SOLAR IRRADIANCE AS REGULATORS OF SEA-SURFACE TEMPERATURE IN ANNUAL AND INTERANNUAL CHANGES SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article; Proceedings Paper CT Miniconference on Observation and Modeling of North Atlantic Deep Water Formation and its Variability CY NOV, 1991 CL COLUMBIA UNIV, LAMONT DOHERTY EARTH OBSERV, PALISADES, NY HO COLUMBIA UNIV, LAMONT DOHERTY EARTH OBSERV ID WESTERN EQUATORIAL PACIFIC; LATENT-HEAT FLUX; OUTGOING LONGWAVE RADIATION; TROPICAL PACIFIC; PRECIPITABLE WATER; SATELLITE DATA; DEEP CONVECTION; LEVEL HUMIDITY; SENSIBLE HEAT; GLOBAL OCEANS AB Seven years of net surface solar irradiance (S) derived from cloud information provided by the International Satellite Cloud Climatology Project and 4 years of surface latent heat flux (E) derived from observations of the special sensor microwave imager were used to examine the relation between surface heat fluxes and sea surface temperature (T(s)) in their global geographical distribution, seasonal cycle, and interannual variation. The relations of seasonal changes imply that evaporation cooling is significant over most of the ocean and that solar heating is the main drive for the change of T(s) away from the equatorial wave guide where ocean dynamics may be more important. However, T(s) is not the most direct and significant factor in the seasonal changes of S and E over most of the ocean; the solar incident angle may be more important to S, and wind speed and air humidity are found to correlate better with E. Significant local correlations between anomalies of T(s) and S and between anomalies of T(s) and E are found in the central equatorial Pacific; both types of correlation are negative. In this area, organized deep convection overlies the warm ocean, forms high clouds, and reduces S, while the low wind speed and high humidity that result from surface convergence reduce E. The negative correlation is not present in the surrounding areas where equally warm water and strong T(s) anomalies are found under a subsiding atmosphere without similarly strong S and E anomalies. Correlation between anomalies of temperature tendency and the fluxes is weak, indicating that other factors are more influential in changing upper ocean heat balance during El Nino. The result shows that the relations between T(s) and the flux components, in annual and interannual timescales, are not universal and not consistent with the local negative feedback postulations which require that an increase in T(s) would result in an increase in local evaporative cooling and a decrease in local solar heating of the ocean. Large-scale atmospheric circulation changes clouds, winds, and humidity; they, in turn, influence the fluxes significantly. The influence of ocean dynamics in changing T(s) in the tropical ocean can not be ignored. C1 LAMONT DOHERTY EARTH OBSERV,PALISADES,NY. RP LIU, WT (reprint author), JET PROP LAB,300-323,PASADENA,CA 91109, USA. NR 49 TC 61 Z9 61 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-OCEANS JI J. Geophys. Res.-Oceans PD JUN 15 PY 1994 VL 99 IS C6 BP 12623 EP 12637 DI 10.1029/94JC00604 PG 15 WC Oceanography SC Oceanography GA NT504 UT WOS:A1994NT50400023 ER PT J AU CANUTO, VM MINOTTI, F RONCHI, C YPMA, RM ZEMAN, O AF CANUTO, VM MINOTTI, F RONCHI, C YPMA, RM ZEMAN, O TI 2ND-ORDER CLOSURE PBL MODEL WITH NEW 3RD-ORDER MOMENTS - COMPARISON WITH LES DATA SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID PLANETARY BOUNDARY-LAYER; REYNOLDS STRESS MODEL; LABORATORY MODEL; TURBULENCE; EVOLUTION; FLOWS AB This paper contains two parts. In the first part, a new set of diagnostic equations is derived for the third-order moments for a buoyancy-driven flow, by exact inversion of the prognostic equations for the third-order moment equations in the stationary case. The third-order moments exhibit a universal structure: they all are a linear combination of the derivatives of all the second-order moments, w2BAR, wthetaBAR, theta2BAR, and q2BAR. Each term of the sum contains a turbulent diffusivity D(t), which also exhibits a universal structure of the form D(t) = anu(t) + bwthetaBAR. Since the sign of the convective flux changes depending on stable or unstable stratification, D(t) varies according to die type of stratification. Here nu(t) approximately wl (l is a mixing length and w is an rms velocity) represents the ''mechanical'' part, while the ''buoyancy'' part is represented by the convective flux wthetaBAR. The quantities a and b are functions of the variable (Ntau)2, where N2 = galpha partial derivative THETA/partial derivative z and tau is the turbulence time scale. The new expressions for the third-order moments generalize those of Zeman and Lumley, which were subsequently adopted by Sun and Ogura, Chen and Cotton, and Finger and Schmidt in their treatments of the convective boundary layer. In the second part, the new expressions for the third-order moments are used to solve the ensemble average equations describing a purely convective boundary layer heated from below at a constant rate. The computed second- and third-order moments are then compared with the corresponding LES results, most of which are obtained by running a new LES code, and part of which are taken from published results. The ensemble average results compare favorably with the LES data. C1 STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305. RP CANUTO, VM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,2880 BROADWAY,GREENBELT,MD 20771, USA. NR 32 TC 81 Z9 84 U1 0 U2 4 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 JUN 15 PY 1994 VL 51 IS 12 BP 1605 EP 1618 DI 10.1175/1520-0469(1994)051<1605:SOCPMW>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA NQ998 UT WOS:A1994NQ99800002 ER PT J AU MISHCHENKO, MI TRAVIS, LD AF MISHCHENKO, MI TRAVIS, LD TI T-MATRIX COMPUTATIONS OF LIGHT-SCATTERING BY LARGE SPHEROIDAL PARTICLES SO OPTICS COMMUNICATIONS LA English DT Article ID NONSPHERICAL PARTICLES; DIELECTRIC OBJECTS; ELEMENTS AB It is well known that T-matrix computations of light scattering by nonspherical particles may suffer from the ill-conditionality of the process of matrix inversion, which has precluded calculations for particle size parameters larger than about 25. It is demonstrated that calculating the T-matrix using extended-precision instead of double-precision floating-point variables is an effective approach for suppressing the numerical instability in computations for spheroids and allows one to increase the maximum particle size parameter for which T-matrix computations converge by as significant a factor as 2-2.7. Yet this approach requires only a negligibly small extra memory, an affordable increase in CPU time consumption, and practically no additional programming effort. As a result, the range of particle size parameters, for which rigorous T-matrix computations of spheroidal scattering can be performed, now covers a substantial fraction of the gap between the domains of applicability of the Rayleigh and geometrical optics approximations. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. RP MISHCHENKO, MI (reprint author), HUGHES STX CORP,NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Mishchenko, Michael/D-4426-2012 NR 32 TC 157 Z9 161 U1 1 U2 13 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0030-4018 J9 OPT COMMUN JI Opt. Commun. PD JUN 15 PY 1994 VL 109 IS 1-2 BP 16 EP 21 DI 10.1016/0030-4018(94)90731-5 PG 6 WC Optics SC Optics GA NR241 UT WOS:A1994NR24100004 ER PT J AU TABIBI, BM TERRELL, CA LEE, JH MINER, G AF TABIBI, BM TERRELL, CA LEE, JH MINER, G TI CW IODINE LASER PERFORMANCE OF T-C4F9I UNDER CLOSELY-SIMULATED AIR-MASS-ZERO SOLAR PUMPING SO OPTICS COMMUNICATIONS LA English DT Article AB The irradiance from a dc solar-simulator source was modified in order to closely-simulate the air-mass-zero (AMO) solar spectrum in the absorption band of the iodides t-C4F9I and n-C3F71. With this modification. the output power of the t-C4F9F laser was measured to be approximately four times that of n-C3F71 for the iodide pressures below 12 Torr. This increase agrees with the previously reported result with a pulsed laser system. A maximum output power of 46 W at a pressure of 6.5 Torr was achieved with the t-C4F9I laser system, which is to our knowledge the highest reported output from a CW photodissociation iodine laser to date. The significant increase of the laser system efficiency comes from the photochemical kinetics favorable to the pump source spectrum and chemical reversibility of the iodide t-C4F9I. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP TABIBI, BM (reprint author), HAMPTON UNIV,DEPT PHYS,HAMPTON,VA 23668, USA. NR 15 TC 1 Z9 1 U1 2 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0030-4018 J9 OPT COMMUN JI Opt. Commun. PD JUN 15 PY 1994 VL 109 IS 1-2 BP 86 EP 92 DI 10.1016/0030-4018(94)90743-9 PG 7 WC Optics SC Optics GA NR241 UT WOS:A1994NR24100016 ER PT J AU MERCER, CR CREATH, K AF MERCER, CR CREATH, K TI LIQUID-CRYSTAL POINT-DIFFRACTION INTERFEROMETER SO OPTICS LETTERS LA English DT Article ID PHASE AB A new point-diffraction interferometer has been developed with a liquid-crystal filter that permits arbitrary phase shifts to be introduced between the object and reference beams. A microsphere embedded within the liquid-crystal layer provides a locally generated reference beam. We phase shift the object beam by varying a voltage across the liquid crystals, thereby altering the refractive index of the birefringent nematic liquid crystals. C1 UNIV ARIZONA,TUCSON,AZ 85721. RP MERCER, CR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 5 TC 46 Z9 46 U1 1 U2 4 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD JUN 15 PY 1994 VL 19 IS 12 BP 916 EP 918 DI 10.1364/OL.19.000916 PG 3 WC Optics SC Optics GA NQ386 UT WOS:A1994NQ38600022 PM 19844487 ER PT J AU WATSON, DM GUPTILL, MT HUFFMAN, JE KRABACH, TN RAINES, SN AF WATSON, DM GUPTILL, MT HUFFMAN, JE KRABACH, TN RAINES, SN TI TEMPERATURE-DEPENDENT COMPENSATION AND OPTICAL QUENCHING BY THERMAL OXYGEN DONORS IN GERMANIUM SO PHYSICAL REVIEW B LA English DT Article ID ELECTRON-PARAMAGNETIC-RESONANCE AB Photothermal ionization spectroscopy of germanium, doped in the impurity-band conduction range with gallium acceptors and with thermal oxygen donors, reveals that the donors and acceptors compensate each other at temperatures higher than about 5 K, but that the impurities coexist as neutral donors and acceptors at lower temperatures. At the lowest temperatures, optical quenching is observed for wavelengths where both impurities have transitions. These effects are used to infer a weak coupling between the neutral acceptor and donor states. The small strength of this coupling sets the thermal oxygen donor apart from all other shallow donors in germanium and silicon. C1 ROCKWELL INT CORP,CTR SCI,ANAHEIM,CA 92803. JET PROP LAB,PASADENA,CA 91109. RP WATSON, DM (reprint author), UNIV ROCHESTER,DEPT PHYS & ASTRON,ROCHESTER,NY 14627, USA. NR 16 TC 1 Z9 1 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 15 PY 1994 VL 49 IS 23 BP 16361 EP 16366 DI 10.1103/PhysRevB.49.16361 PG 6 WC Physics, Condensed Matter SC Physics GA NT525 UT WOS:A1994NT52500031 ER PT J AU BERKIN, AL HELLINGS, RW AF BERKIN, AL HELLINGS, RW TI MULTIPLE FIELD SCALAR-TENSOR THEORIES OF GRAVITY AND COSMOLOGY SO PHYSICAL REVIEW D LA English DT Article ID HIGHER-DIMENSIONAL COSMOLOGY; INFLATIONARY UNIVERSE; RELATIVISTIC GRAVITY; EXTENDED INFLATION; STABILITY; ATTRACTOR; FLATNESS; HORIZON; MODELS AB We consider multiple scalar fields coupled to gravity, with special attention given to two-field theories. First, the conditions necessary for these theories to exactly meet solar system tests are given. We find, in particular, that these constraints require that some scalar kinetic terms be non-positive-definite. Next, we investigate the cosmological evolution of the fields to see if these conditions can be met. Solutions are found in the dust era, as well as radiation- and cosmological-constant-dominated epochs. The possibility of inflation in these theories is discussed. While power law growth of the scalar fields can yield the appropriate conditions to meet solar system constraints, these solutions are unstable. RP BERKIN, AL (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. OI Berkin, Andrew/0000-0002-2051-6982 NR 25 TC 17 Z9 17 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD JUN 15 PY 1994 VL 49 IS 12 BP 6442 EP 6449 DI 10.1103/PhysRevD.49.6442 PG 8 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA NT526 UT WOS:A1994NT52600017 ER PT J AU CLARK, RK WALLACE, TA AF CLARK, RK WALLACE, TA TI STATIC AND DYNAMIC OXIDATION OF PT-CLAD MO-47RE ALLOY SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article RP CLARK, RK (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 8 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 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD JUN 15 PY 1994 VL 30 IS 12 BP 1535 EP 1540 DI 10.1016/0956-716X(94)90304-2 PG 6 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA NE943 UT WOS:A1994NE94300008 ER PT J AU KRISHNAKUMAR, E SRIVASTAVA, SK AF KRISHNAKUMAR, E SRIVASTAVA, SK TI ELECTRON CORRELATION-EFFECTS IN THE DISSOCIATIVE IONIZATION OF H2 SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Letter ID FULLY STRIPPED IONS; VELOCITY N-7+ IONS; CROSS-SECTIONS; SINGLE IONIZATION; HELIUM; PROTONS; IMPACT; PROJECTILES; ANTIPROTONS; COLLISIONS AB The dissociative and non-dissociative ionization of H-2 by electron impact has been measured up to 1 keV incident energy using a pulsed electron beam and pulsed ion extraction technique in conjunction with a time-of-flight spectrometer and relative flow technique. These data represent the first accurate measurement on the dissociative ionization of H-2 by electron impact over such a large energy range. It has been shown that the ratio, R*, of the dissociative ionization cross section to non-dissociative ionization cross section in H-2 serves as a useful parameter in probing the electron correlation effects. A comparison of the value of R* obtained by electron impact with those obtained by proton and antiproton impact shows strong dependence on the sign of the projectile charge. C1 JET PROP LAB,PASADENA,CA 91109. RP KRISHNAKUMAR, E (reprint author), TATA INST FUNDAMENTAL RES,HOMI BHABHA RD,BOMBAY 400005,INDIA. NR 28 TC 40 Z9 40 U1 0 U2 4 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD JUN 14 PY 1994 VL 27 IS 11 BP L251 EP L258 DI 10.1088/0953-4075/27/11/004 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA NV169 UT WOS:A1994NV16900004 ER PT J AU DODELSON, S GYUK, G TURNER, MS AF DODELSON, S GYUK, G TURNER, MS TI IS A MASSIVE TAU-NEUTRINO JUST WHAT COLD DARK-MATTER NEEDS SO PHYSICAL REVIEW LETTERS LA English DT Article ID LARGE-SCALE STRUCTURE; INFLATIONARY UNIVERSE; COBE; SCENARIO; HOT; ANISOTROPIES; GALAXIES; MODELS; TESTS AB The cold dark matter scenario for structure formation in the Universe has many successes; however, when its spectrum of density perturbations is normalized to the Cosmic Background Explorer anisotropy measurement the level of inhomogeneity predicted on small scales is too large. This can be remedied by a tau neutrino of mass 1-10 MeV and lifetime 0.1-100 sec whose decay products include electron neutrinos because it allows the total energy density in relativistic particles to be doubled without interfering with nucleosynthesis. C1 UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP DODELSON, S (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. NR 38 TC 55 Z9 55 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 JUN 13 PY 1994 VL 72 IS 24 BP 3754 EP 3757 DI 10.1103/PhysRevLett.72.3754 PG 4 WC Physics, Multidisciplinary SC Physics GA NT460 UT WOS:A1994NT46000003 ER PT J AU NOEVER, D CRONISE, R AF NOEVER, D CRONISE, R TI IS BIOLUMINESCENT TURBULENCE AN EXAMPLE OF SELF-ORGANIZED CRITICALITY SO PHYSICS LETTERS A LA English DT Article ID GONYAULAX-POLYEDRA AB When mechanically stimulated by flow, some marine cells react by flashing blue light or bioluminescing. The flash response give a relatively non-invasive measure of turbulent behavior which lends itself readily and quantitatively to statistical models of fluid structure. We report substantial agreement between a series of experiments performed using stimulated light from the bioluminescence of seawater flowing through a glass pipe and theoretical predictions based on models proposed for describing a self-organized critical phenomenon. In this way, bioluminescent turbulent flow can be taken as a natural and potentially robust example connecting long-held scaling problems in turbulence to recent thinking on fractals and self-organized criticality. RP NOEVER, D (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH ES76,HUNTSVILLE,AL 35812, USA. NR 23 TC 2 Z9 2 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0375-9601 J9 PHYS LETT A JI Phys. Lett. A PD JUN 13 PY 1994 VL 189 IS 3 BP 176 EP 180 DI 10.1016/0375-9601(94)90633-5 PG 5 WC Physics, Multidisciplinary SC Physics GA NR153 UT WOS:A1994NR15300007 ER PT J AU BRAINERD, JJ AF BRAINERD, JJ TI PRODUCING THE UNIVERSAL SPECTRUM OF COSMOLOGICAL GAMMA-RAY BURSTS WITH THE KLEIN-NISHINA CROSS-SECTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY, THEORY; GAMMA RAYS, BURSTS ID ACTIVE GALACTIC NUCLEI; GALAXIES; BATSE AB A power-law spectrum attenuated through Compton scattering by an optically thick medium produces spectra that have a characteristic energy of several hundred keV. Add a redshift, and one finds that this model can qualitatively reproduce the color-color diagrams found for individual gamma-ray bursts. This model is easily tested through model fits to burst spectra and through comparisons of the parameters derived from model fits to the limits on parameters derived from the burst log N - log P(max) curve. The heavy attenuation makes the amount of energy released in the burst almost-equal-to 10(3) times larger than is inferred from the observed flux. The requirements of high optical depth and no photon-photon pair creation place a lower limit on the size of the scattering region. This size suggests that the attenuation occurs in giant molecular clouds in the cores of galaxies. This indicates that gamma-ray bursts are probably from supermassive black holes. If the Lorentz factor of the radiation source is large, the optical depth, and therefore the hardness ratio of a burst, can change over the duration of the burst. RP BRAINERD, JJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,UNIV ALABAMA,SPACE SCI LAB,ES-66,HUNTSVILLE,AL 35812, USA. NR 26 TC 40 Z9 40 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 1994 VL 428 IS 1 BP 21 EP 27 DI 10.1086/174215 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR115 UT WOS:A1994NR11500003 ER PT J AU NEUFELD, DA HOLLENBACH, DJ AF NEUFELD, DA HOLLENBACH, DJ TI DENSE MOLECULAR SHOCKS AND ACCRETION ONTO PROTOSTELLAR DISKS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS; ISM, MOLECULES; SHOCK WAVES; STARS, PRE-MAIN-SEQUENCE ID INFRARED CO EMISSION; CLOUD CORES; GRAINS; GAS; REFORMATION; IONIZATION; COLLAPSE AB We have examined the physical and chemical processes which accompany the propagation of a J-type shock through molecular astrophysical gas of density 10(7.5)-10(12) H nuclei per cm3. Our study is primarily relevant to the high-density accretion shocks which are associated with the supersonic infall of material during the collapse of a molecular cloud core to form a protostar. We have carried out a general parameter study to determine the characteristic infrared emission spectrum of dense molecular shocks and the extent of grain destruction within such shocks as a function of relevant shock parameters. Accretion shocks with mass accretion rates greater than or similar to 10(-5) M. yr-1 are plausible sources of the CO v = 2-0 vibrational band emission observed in many protostars, at least for sources of moderate CO v = 2-0 luminosity (less than or similar to few X 10(23) W). Rovibrational emissions from H2O and OH are also predicted to be luminous in dense molecular accretion shocks. Vaporization is the dominant mechanism of grain destruction within dense molecular shocks, leading to the efficient removal of those grains which are heated to their vaporization temperature by the combined effects of radiative heating, drag heating, and thermal heating by the hot postshock gas. The criteria for grain vaporization are obtained for grains composed of several different materials: metallic iron, silicate, troilite, refractory organic materials, volatile organic materials, and water ice. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP NEUFELD, DA (reprint author), JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,3400 N CHARLES ST,BALTIMORE,MD 21218, USA. NR 37 TC 86 Z9 86 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 1994 VL 428 IS 1 BP 170 EP 185 DI 10.1086/174230 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR115 UT WOS:A1994NR11500018 ER PT J AU NATTA, A WALMSLEY, CM TIELENS, AGGM AF NATTA, A WALMSLEY, CM TIELENS, AGGM TI CARBON RECOMBINATION LINES AS A DIAGNOSTIC OF PHOTODISSOCIATION REGIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE H-II REGIONS; INFRARED, ISM, LINES AND BANDS; RADIO LINES, ISM ID ORION MOLECULAR CLOUD; ULTRAVIOLET-RADIATION; EMISSION; NEBULA; GAS; SPECTROSCOPY; NGC-2023; MODEL; DUST; M42 AB We have observed the C91alpha radio recombination line toward the Orion H II region. This narrow (approximately 3-5 km s-1 FWHM) line is spatially very extended (approximately 8' or 1 pc). These characteristics compare well with the observed characteristics of the C II fine structure line at 158 mum. Thus, the C91alpha line originates in the predominantly neutral photodissociation regions separating the H II region from the molecular cloud. We have developed theoretical models for the C ii radio recombination lines from photodissociation regions. The results show that the I(C91alpha)/I(C158) intensity ratio is a sensitive function of the temperature and density of the emitting gas. We have also extended existing theoretical models for photodissociation regions to include the C II recombination lines. Comparison with these models show that, in the central portion of the Orion region, the C91alpha line originates in dense (10(6) cm-3), warm (500-1000 K) gas. Even at large projected distances (approximately 1 pc), the inferred density is still high (10(5) cm-3) and implies extremely high thermal pressures. As in the case of the [C II] 158 mum line, the large extent of the C91alpha line shows that FUV photons can penetrate to large distances from the illuminating source. The decline of the intensity of the incident radiation field with distance from THETA1 C seems to be dominated by geometrical dilution, rather than dust extinction. Finally, we have used our models to calculate the intensity of the 9850 angstrom recombination line of C II. The physical conditions inferred from this line are in good agreement with those determined from the radio recombination and the far-infrared fine-structure lines. We show that the ratio of the 9850 angstrom to the C91alpha line is a very good probe of very high density clumps. C1 MAX PLANCK INST RADIOASTRON,D-53121 BONN,GERMANY. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP NATTA, A (reprint author), OSSERVATORIO ARCETRI,LARGO FERMI 5,I-50125 FLORENCE,ITALY. NR 40 TC 33 Z9 33 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 10 PY 1994 VL 428 IS 1 BP 209 EP 218 DI 10.1086/174232 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR115 UT WOS:A1994NR11500020 ER PT J AU SWARTZ, DA AF SWARTZ, DA TI CHARGE-TRANSFER IN HELIUM-RICH SUPERNOVA PLASMA SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC DATA; ATOMIC PROCESSES; PLASMAS; SUPERNOVAE, GENERAL ID IB SUPERNOVAE; CROSS-SECTIONS; LIGHT CURVES; STAR MODELS; IONS; COLLISIONS; HYDROGEN; NUCLEOSYNTHESIS; IONIZATION; SYSTEMS AB Charge transfer rate coefficients are estimated using Landau-Zener and modified Demkov approximations. The coefficients, augmented by those available from the literature, are used in statistical equilibrium equations describing the state of helium-rich supernova plasma. Such a plasma may describe both Type Ib and Type Ic supernova ejecta. The hypothesis that extensive mixing of metals with helium in Type Ic supernovae may provide a catalyst for rapid charge transfer that weakens the helium line emission by altering the excitation balance is tested. It is shown that charge transfer as a mechanism for suppressing helium line emission is ineffective unless the metal abundance is comparable to or larger than the helium abundance. This result supports an earlier conclusion that Type Ic supernovae must be helium poor relative to Type Ib events. RP SWARTZ, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,XRAY ASTRON BRANCH,ES-65,HUNTSVILLE,AL 35812, USA. NR 72 TC 13 Z9 13 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 1994 VL 428 IS 1 BP 267 EP 274 DI 10.1086/174238 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR115 UT WOS:A1994NR11500026 ER PT J AU LEITHERER, C ALLEN, R ALTNER, B DAMINELI, A DRISSEN, L IDIART, T LUPIE, O NOTA, A ROBERT, C SCHMUTZ, W SHORE, SN AF LEITHERER, C ALLEN, R ALTNER, B DAMINELI, A DRISSEN, L IDIART, T LUPIE, O NOTA, A ROBERT, C SCHMUTZ, W SHORE, SN TI GEOMETRY AND PHYSICAL CONDITIONS IN THE STELLAR WIND OF AG-CARINAE SO ASTROPHYSICAL JOURNAL LA English DT Article DE POLARIZATION; STARS, EVOLUTION; STARS, INDIVIDUAL (AG CARINAE); STARS, MASS LOSS; SUPERGIANTS; ULTRAVIOLET, STARS ID WOLF-RAYET STARS; RADIATION-DRIVEN WINDS; HOT LUMINOUS STARS; P-CYGNI; S-DOR; WAVELENGTH DEPENDENCE; LINEAR-POLARIZATION; MASS-LOSS; INTERSTELLAR POLARIZATION; INTRINSIC POLARIZATION AB AG Carinae is one of the prototypes of the class of Luminous Blue Variables. Since 1990 the star has continuously brightened in its visual continuum. We report on a multi-instrument and -wavelength observing campaign to monitor the current activity phase of AG Car. Ground-based photometry, polarimetry, spectroscopy, and space-ultraviolet spectroscopy and spectropolarimetry have been obtained. From the variability of the polarization at ultraviolet and optical wavelengths we detect significant intrinsic polarization. P(int) greater-than-or-equal-to 0.5% is a large value for a hot, luminous star, suggesting departures from spherical symmetry in the wind of AG Car. The intrinsic polarization is variable on a timescale of 2 months or less. The measured ultraviolet polarization (intrinsic + interstellar) dropped to 0.5% in 1992 May and returned to 1% in 1992 July. The results are interpreted in terms of a variable outflow with a density enhancement in the equatorial plane. A similar model was suggested for the related object R127 in the Large Magellanic Cloud. This geometry is reminiscent of the large-scale morphology of the gas nebula and dust ''jet'' surrounding AG Car. It is therefore likely that physical conditions close to the stellar surface are responsible for the geometry of the spatially resolved circumstellar material around AG Car. The line spectrum in the optical and ultraviolet is dominated by the effects of a massive stellar wind. Two wind components are detected: a slow dense wind, where the bulk of recombination radiation is emitted, and a faster, less dense wind, visible in the absorption components of ultraviolet P Cygni profiles. This wind structure is consistent with the geometry suggested by the spectropolarimetric observations, and it is reminiscent of the wind conditions prevailing in B[e] stars. An analysis of the photospheric and wind parameters has been performed using an expanding, spherically extended non-LTE model atmosphere. The temperature of AG Car decreased from 21,000 to 14,000 K over approximately 1 yr, with a corresponding increase of the photospheric radius by a factor of 2. Helium is found to be significantly overabundant, supporting the very evolved state of AG Car. Comparison with evolutionary models leads to an estimate for the zero-age main-sequence mass of (50 +/- 10) M.. Therefore the possibility cannot entirely be excluded that AG Car is in a post-red supergiant phase. Despite the drastic change of the photospheric conditions, the mass-loss rate did not increase. We find no evidence for a positive correlation between wind density and stellar radius. This makes models that explain the radius increase by opacity effects in the outflow unlikely. The mechanism responsible for the temperature and radius variations is still unknown but most likely has its origin in subphotospheric regions. C1 UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. APPL RES CORP,LANDOVER,MD 20758. UNIV SAO PAULO,INST ASTRON & GEOFIS,BR-01065 SAO PAULO,BRAZIL. EUROPEAN SPACE AGCY,DEPT SPACE SCI,DIV ASTROPHYS,F-75738 PARIS 15,FRANCE. SWISS FED INST TECHNOL,INST ASTRON,CH-8092 ZURICH,SWITZERLAND. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP LEITHERER, C (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. RI Damineli, Augusto/D-8210-2012; Idiart, Thais/K-9872-2016; Schmutz, Werner/B-4153-2014 OI Damineli, Augusto/0000-0002-7978-2994; Schmutz, Werner/0000-0003-1159-5639 NR 116 TC 71 Z9 71 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 10 PY 1994 VL 428 IS 1 BP 292 EP 318 DI 10.1086/174241 PN 1 PG 27 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR115 UT WOS:A1994NR11500029 ER PT J AU SIMON, T LANDSMAN, WB GILLILAND, RL AF SIMON, T LANDSMAN, WB GILLILAND, RL TI A SEARCH FOR CHROMOSPHERIC EMISSION IN A-TYPE STARS USING THE GODDARD HIGH-RESOLUTION SPECTROGRAPH SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, ACTIVITY; STARS, CHROMOSPHERES; STARS, INDIVIDUAL (ALPHA-AQUILAE); ULTRAVIOLET, STARS ID LYMAN-ALPHA EMISSION; MAIN-SEQUENCE STARS; CONVECTION ZONES; MASS-LOSS; EVOLUTION; ROTATION; DIAGRAM; DWARF; LINE AB We have used the Goddard High-Resolution Spectrograph on the Hubble Space Telescope to search for chromospheric emission in the ultraviolet C II 1335 angstrom lines of eight A-type stars. The B - V colors of these stars range from 0.12 to 0.22. We have detected emission in the spectrum of the A7 V star Altair, but in no other star. We present tentative evidence that the emission from Altair is blueshifted by approximately 60 km s-1 or more with respect to the photospheric spectrum of this star. We interpret this as expansion and suggest that the base of the A star winds that we have proposed in earlier work may lie within the chromosphere. Together with IUE spectra, our observations indicate that in ordinary main-sequence stars the onset of convection zones capable of supporting detectable chromospheres occurs in the close vicinity of B - V = 0.22. C1 NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. RP SIMON, T (reprint author), UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822, USA. NR 34 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 1994 VL 428 IS 1 BP 319 EP 323 DI 10.1086/174242 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR115 UT WOS:A1994NR11500030 ER PT J AU CARPENTER, KG ROBINSON, RD WAHLGREN, GM LINSKY, JL BROWN, A AF CARPENTER, KG ROBINSON, RD WAHLGREN, GM LINSKY, JL BROWN, A TI GHRS OBSERVATIONS OF COOL, LOW-GRAVITY STARS .1. THE FAR-ULTRAVIOLET SPECTRUM OF ALPHA-ORIONIS (M2 IAB) SO ASTROPHYSICAL JOURNAL LA English DT Article DE LINE, IDENTIFICATION; STARS, CHROMOSPHERES; STARS, INDIVIDUAL (ALPHA-ORIONIS); STARS, LATE-TYPE; SUPERGIANTS; ULTRAVIOLET, STARS ID S-I EMISSION; GIANT STARS; IUE SPECTRA; FE-II; CHROMOSPHERES; ATMOSPHERES; BETELGEUSE; EXCITATION; LINES AB We present far-UV (1200-1930 angstrom) observations of the prototypical red supergiant star alpha Ori, obtained with the Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope. The observations, obtained in both low- (G140L) and medium- (G160/200M) resolution modes, unamibiguously confirm that the UV ''continuum'' tentatively seen with IUE is in fact a true continuum and is not due to a blend of numerous faint emission features or scattering inside the IUE spectrograph. This continuum appears to originate in the chromosphere of the star, at temperatures ranging from 3000-5000 K, and we argue that it is not related to previously reported putative companions or to bright spots on the stellar disk. Its stellar origin is further confirmed by overlying atomic and molecular absorptions from the chromosphere and circumstellar shell. The dominant structure in this spectral region is due to nine strong, broad absorption bands of the fourth-positive A-X system of CO, superposed on this continuum in the 1300-1600 angstrom region. Modeling of this CO absorption indicates that it originates in the circumstellar shell in material characterized by T = 500 K, N(CO) = 1.0 x 10(18) cm-2, and V(turb) = 5.0 km s-1. The numerous chromospheric emission features are attributed mostly to fluorescent lines of Fe II and Cr II (both pumped by Lyalpha) and S I lines, plus a few lines of O I, C I, and Si II. The O I and C I UV 2 multiplets are very deficient in flux, compared to both the flux observed in lines originating from common upper levels but with markedly weaker intrinsic strength (i.e., O I UV 146 and C I UV 32) and to the UV 2 line fluxes seen in other cool, less luminous stars. This deficiency appears to be caused by strong self-absorption of these resonance lines in the circumstellar shell and/or upper chromosphere of alpha Ori. Atomic absorption features, primarily due to C I and Fe II are clearly seen in the G160M spectrum centered near 1655 angstrom. These Fe ii features are formed at temperatures that can occur only in the chromosphere of the star and are clearly not photospheric or circumstellar in origin. C1 NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON PROGRAMS,GREENBELT,MD 20771. UNIV COLORADO,NATL INST STAND & TECHNOL,JOINT INST LAB ASTROPHYS,BOULDER,CO 80302. RP CARPENTER, KG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Carpenter, Kenneth/D-4740-2012 NR 65 TC 42 Z9 42 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 1994 VL 428 IS 1 BP 329 EP 344 DI 10.1086/174244 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR115 UT WOS:A1994NR11500032 ER PT J AU MURAKAMI, H BOCK, J FREUND, MM GUO, H HIRAO, T LANGE, AE MATSUHARA, H MATSUMOTO, T MATSUURA, S MCMAHON, TJ MURAKAMI, M NAKAGAWA, T NODA, M NOGUCHI, K OKUDA, H OKUMURA, K ONAKA, T ROELLIG, TL SATO, S SHIBAI, H TANABE, T WATABE, T YAGI, T YAJIMA, N YUI, M AF MURAKAMI, H BOCK, J FREUND, MM GUO, H HIRAO, T LANGE, AE MATSUHARA, H MATSUMOTO, T MATSUURA, S MCMAHON, TJ MURAKAMI, M NAKAGAWA, T NODA, M NOGUCHI, K OKUDA, H OKUMURA, K ONAKA, T ROELLIG, TL SATO, S SHIBAI, H TANABE, T WATABE, T YAGI, T YAJIMA, N YUI, M TI THE INFRARED TELESCOPE IN-SPACE (IRTS) SO ASTROPHYSICAL JOURNAL LA English DT Article DE ARTIFICIAL SATELLITES, SPACE PROBES; INFRARED, GENERAL; TELESCOPES ID BACKGROUND EXPLORER COBE; 158 MICRON EMISSION; INTERSTELLAR-MEDIUM; GALAXY AB The Infrared Telescope in Space (IRTS) is a cryogenically cooled small infrared telescope that will fly aboard the small space platform Space Flyer Unit. It will survey approximately 10% of the sky with a relatively wide beam during its 20 day mission. Four focal-plane instruments will make simultaneous observations of the sky at wavelengths ranging from 1 to 1000 mum. The IRTS will provide significant information on cosmology, interstellar matter, late-type stars, and interplanetary dust. This paper describes the instrumentation and mission. C1 UNIV TSUKUBA,INST ENGN MECH,TSUKUBA,IBARAKI 305,JAPAN. TOKYO METROPOLITAN INST TECHNOL,DEPT MECH SYST ENGN,HINO,TOKYO 191,JAPAN. UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. NAGOYA UNIV,SCH SCI,DEPT ASTROPHYS,CHIKUSA KU,NAGOYA,AICHI 464,JAPAN. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. UNIV TOKYO,TOKYO ASTRON OBSERV,FAC SCI,INST ASTRON,MITAKA,TOKYO 181,JAPAN. RP MURAKAMI, H (reprint author), INST SPACE & ASTRONAUT SCI,YOSHINODAI 3-1-1,SAGAMIHARA,KANAGAWA 229,JAPAN. RI Matsuura, Shuji/B-5658-2016 OI Matsuura, Shuji/0000-0002-5698-9634 NR 25 TC 32 Z9 32 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 10 PY 1994 VL 428 IS 1 BP 354 EP 362 DI 10.1086/174246 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR115 UT WOS:A1994NR11500034 ER PT J AU ROELLIG, TL ONAKA, T MCMAHON, TJ TANABE, T AF ROELLIG, TL ONAKA, T MCMAHON, TJ TANABE, T TI THE MIDINFRARED SPECTROMETER ON THE INFRARED TELESCOPE IN-SPACE (IRTS) MISSION SO ASTROPHYSICAL JOURNAL LA English DT Article DE ARTIFICIAL SATELLITES, SPACE PROBES; INFRARED, GENERAL; INSTRUMENTATION, SPECTROGRAPHS AB The Mid-Infrared Spectrometer (MIRS) is one of the four focal plane instruments on the Infrared Telescope in Space (IRTS) mission. The instrument has been constructed, tested, and calibrated in the laboratory and is presently scheduled to be launched by a Japanese expendable launch vehicle as part of the Space Flyer Unit-1 mission in early 1995. The wavelength coverage of the MIRS ranges from 4.5 to 11.7 mum, with a spectral resolution of 0.23 to 0.36 mum. With the cryogenically cooled optics of the IRTS telescope assembly, the MIRS will be able to make an extremely sensitive survey of both point-source and extended objects over an estimated 10% of the sky. C1 UNIV TOKYO, SCH SCI, DEPT ASTRON, BUNKYO KU, TOKYO 113, JAPAN. YERKES OBSERV, WILLIAMS BAY, WI 53191 USA. UNIV TOKYO, TOKYO ASTRON OBSERV, FAC SCI, INST ASTRON, MITAKA, TOKYO 181, JAPAN. RP NASA, AMES RES CTR, MS 245-6, MOFFETT FIELD, CA 94035 USA. NR 15 TC 30 Z9 30 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 10 PY 1994 VL 428 IS 1 BP 370 EP 376 DI 10.1086/174248 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR115 UT WOS:A1994NR11500036 ER PT J AU SADDOUGHI, SG VEERAVALLI, SV AF SADDOUGHI, SG VEERAVALLI, SV TI LOCAL ISOTROPY IN TURBULENT BOUNDARY-LAYERS AT HIGH REYNOLDS-NUMBER SO JOURNAL OF FLUID MECHANICS LA English DT Article ID DISSIPATION-RANGE; SCALE TURBULENCE; CHANNEL FLOW; VELOCITY; HYPOTHESIS; SPECTRA; WALL AB To test the local-isotropy predictions of Kolmogorov's (1941) universal equilibrium theory, we have taken hot-wire measurements of the velocity fluctuations in the test-section-ceiling boundary layer of the 80 x 120 foot Full-Scale Aerodynamics Facility at NASA Ames Research Center, the world's largest wind tunnel. The maximum Reynolds numbers based on momentum thickness, R(theta), and on Taylor microscale, R(lambda), were approximately 370000 and 1450 respectively. These are the largest ever attained in laboratory boundary-layer flows. The boundary layer develops over a rough surface, but the Reynolds-stress profiles agree with canonical data sufficiently well for present purposes. Spectral and structure-function relations for isotropic turbulence were used to test the local-isotropy hypothesis, and our results have established the condition under which local isotropy can be expected. To within the accuracy of measurement, the shear-stress cospectral density E12(k1), which is the most sensitive indicator of local isotropy, fell to zero at a wavenumber about a decade larger than that at which the energy spectra first followed -5/3 power laws. At the highest Reynolds number, E12(k1) vanished about one decade before the start of the dissipation range, and it remained zero in the dissipation range. The lower wavenumber limit of locally isotropic behaviour of the shear-stress cospectra is given by k1(epsilon/S3)1/2 almost-equal-to 10 where S is the mean shear, partial derivative U/partial derivative y. The current investigation also indicates that for energy spectra this limit may be relaxed to k1(epsilon/S3)1/2 almost-equal-to 3; this is Corrsin's (1958) criterion, with the numerical value obtained from the present data. The existence of an isotropic inertial range requires that this wavenumber be much less than the wavenumber at the onset of viscous effects, k1 eta much less than 1, so that the combined condition (Corrsin 1958; Uberoi 1957), is S(nu/epsilon)1/2 much less than 1. Among other detailed results, it was observed that in the dissipation range the energy spectra had a simple exponential decay (Kraichnan 1959) with an exponent prefactor close to the value 8 = 5.2 obtained in direct numerical simulations at low Reynolds number. The inertial-range constant for the three-dimensional spectrum, C, was estimated to be 1.5+/-0.1 (Monin & Yaglom 1975). Spectral 'bumps' between the -5/3 inertial range and the dissipative range were observed on all the compensated energy spectra. The shear-stress cospectra rolled-off with a -7/3 power law before the start of local isotropy in the energy spectra, and scaled linearly with S (Lumley 1967). In summary, it is shown that one decade of inertial subrange with truly negligible shear-stress cospectral density requires S(nu/epsilon)1/2 of not more than about 0.01 (for a shear layer with turbulent kinetic energy production approximately equal to dissipation, a microscale Reynolds number of about 1500). For practical purposes many of the results of the hypothesis may be relied on at somewhat lower Reynolds numbers. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SADDOUGHI, SG (reprint author), STANFORD UNIV,CTR TURBULENCE RES,BLDG 500,STANFORD,CA 94305, USA. NR 77 TC 455 Z9 459 U1 5 U2 60 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 10 PY 1994 VL 268 BP 333 EP 372 DI 10.1017/S0022112094001370 PG 40 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA NT038 UT WOS:A1994NT03800014 ER PT J AU CRISP, J BALOGA, S AF CRISP, J BALOGA, S TI INFLUENCE OF CRYSTALLIZATION AND ENTRAINMENT OF COOLER MATERIAL ON THE EMPLACEMENT OF BASALTIC AA LAVA FLOWS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID CHEMICAL MASS-TRANSFER; SIZE DISTRIBUTION CSD; LAKE COOLING MODELS; MOUNT ETNA; MAGMATIC PROCESSES; NUMERICAL-ANALYSIS; RHEOLOGY; KINETICS; DYNAMICS; FIELD AB A theoretical model is used to describe and investigate the effects of simultaneous crystallization, radiation loss, and entrainment of cooler material on the temperature of a well-mixed core of an active aa lava flow. Entrainment of crust, levee debris, and base material into the interior of active flows has been observed, but the degree of assimilation and the thermal consequences are difficult to quantify. The rate of entrainment can be constrained by supplementing the theoretical model with information on the crystallization along the path of the flow and estimation of the radiative loss from the flow interior. Application of the model is demonstrated with the 1984 Mauna Loa flow, which was erupted about 30-degrees-C undercooled. Without any entrainment of cooler material, the high crystallization rates would have driven temperatures in the core well above temperatures measured by thermocouple and estimated from glass geothermometry. One plausible scenario for this flow, which agrees with available temperature and crystallinity measurements, has a high initial rate of entrainment during the first 8 hours of travel (a mass ratio of entrained material to fluid core of about 15% if the average temperature of the entrained material was 600-degrees-C), which counterbalances the latent heat from approximately 40% crystallization. In this scenario, the model suggests an additional 5% crystallization and a 5% entrainment mass ratio over the subsequent 16-hour period. Measurements of crystallization, radiative losses, and entrainment factors are necessary for understanding the detailed thermal histories of active lava flows. RP CRISP, J (reprint author), JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Crisp, Joy/H-8287-2016 OI Crisp, Joy/0000-0002-3202-4416 NR 49 TC 69 Z9 69 U1 0 U2 6 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 JUN 10 PY 1994 VL 99 IS B6 BP 11819 EP 11831 DI 10.1029/94JB00134 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NT168 UT WOS:A1994NT16800018 ER PT J AU FULLERTON, LG FREY, HV ROARK, JH THOMAS, HH AF FULLERTON, LG FREY, HV ROARK, JH THOMAS, HH TI CONTRIBUTIONS OF CRETACEOUS QUIET ZONE NATURAL REMANENT MAGNETIZATION TO MAGSAT ANOMALIES IN THE SOUTHWEST INDIAN-OCEAN SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH LA English DT Article ID DRONNING-MAUD-LAND; MOZAMBIQUE BASIN; CRUSTAL MAGNETIZATION; SEISMIC REFRACTION; MADAGASCAR RIDGE; AGULHAS PLATEAU; FRACTURE-ZONE; SOMALI BASIN; GEOID HEIGHT; SEA-FLOOR AB The Magsat magnetic anomalies over the Southwest Indian Ocean are modeled using a combination of induced plus viscous remanent magnetization (IM/VRM) and natural remanent magnetization (NRM). Two broad, roughly parallel, SW to NE trending triple-peaked positive anomalies dominate the region, one lying south of Africa and the other north of Antarctica. Although these anomaly peaks generally correspond with the Agulhas Plateau/Maud Rise, Mozambique Plateau/Astrid Ridge, and Madagascar Ridge/Conrad Rise conjugate pairs, the IM/VRM contribution from structural characteristics (i.e., crustal thickness) accounts for only about 20% of the anomaly amplitudes. A spatially variable but observationally constrained NRM contribution in Cretaceous Quiet Zone (KQZ) crust is required to account for the location, shape, and amplitude contrast of these anomalies. Many crustal features in the Southwest Indian Ocean near Antarctica have little geophysical data to constrain their structure but do have tectonic conjugates near Africa for which much more geophysical data are generally available. Using geophysical and geological constraints from one member to model the magnetization structure of its conjugate reproduces the observed Magsat reduced-to-pole anomalies over both structures very well. This suggests that no significant alteration in their magnetization structure has occurred since the features split. Models of these conjugate structures show that IM/VRM reproduces the Magsat anomalies associated with non-KQZ crust but that both IM/VRM and a dominant NRM component are required to explain the anomalies associated with KQZ crust. C1 NASA, GODDARD SPACE FLIGHT CTR, GEODYNAM BRANCH, GREENBELT, MD 20771 USA. SCI SYST & APPLICAT INC, LANHAM, MD 20706 USA. UNIV MARYLAND, ASTRON PROGRAM, COLL PK, MD 20742 USA. RP FULLERTON, LG (reprint author), LANDON SCH, 6101 WILSON LANE, BETHESDA, MD 20817 USA. NR 88 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9313 EI 2169-9356 J9 J GEOPHYS RES-SOL EA JI J. Geophys. Res.-Solid Earth PD JUN 10 PY 1994 VL 99 IS B6 BP 11923 EP 11936 DI 10.1029/94JB00645 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA NT168 UT WOS:A1994NT16800025 ER PT J AU SMITH, GD JAFFE, RL YOON, DY AF SMITH, GD JAFFE, RL YOON, DY TI CONFORMATIONAL CHARACTERISTICS OF POLY(TETRAFLUOROETHYLENE) CHAINS BASED UPON AB-INITIO ELECTRONIC-STRUCTURE CALCULATIONS ON MODEL MOLECULES SO MACROMOLECULES LA English DT Article ID STATISTICS; SPECTRA; STATE AB Conformational characteristics of poly(tetrafluoroethylene) (PTFE) chains have been studied in detail, based upon ab initio electronic structure calculations on perfluorobutane, perfluoropentane, and perfluorohexane. The conformational energy contours confirm the well-known minima of the trans states at +/- 17-degrees but also show that the gauche states split as well, with minima at +/- 124-degrees and +/- 84-degrees, in order to relieve steric crowding. The directions of such split distortions from the perfectly staggered states are strongly coupled for adjacent pairs of bonds in a manner identical to the intradyad pair of poly(isobutylene) chains. These conformational characteristics are fully represented by a six-state rotational isomeric state (RIS) model comprised of t+, t-, g++, g+-, g-+, and g-- states, located at the split energy minima. The resultant 6 X 6 statistical weight matrix is described by two first-order interaction parameters and two second-order interaction parameters; the ab initio estimated first-order interaction energies are ca. 0.6 kcal/mol for the g++ states and ca. 2.0 kcal/mol for the g+- states, while the second-order interaction energies are ca. 0.6 kcal/mol for the g++g++ states and ca. 1.0 kcal/mol for the g++g-+ states, according to MP2 level ab initio calculations using a D95+* basis set. This six-state RIS model, with no adjustment of the geometric or energy parameters as determined from the ab initio calculations, predicts the unperturbed chain dimensions, and the fraction of gauche bonds as a function of temperature, in good agreement with available experimental values. Compared with the previous four-state RIS model of Bates and Stockmayer, our six-state model differs significantly in that it fully takes into account the strong coupling of conformations for adjacent bond pairs, which leads to important differences in the nature and the magnitude of the interactions involving the gauche conformations between the two models. C1 IBM CORP,ALMADEN RES CTR,650 HARRY RD,SAN JOSE,CA 95120. NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035. NASA,MOFFETT FIELD,CA 94035. NR 20 TC 69 Z9 69 U1 2 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD JUN 6 PY 1994 VL 27 IS 12 BP 3166 EP 3173 DI 10.1021/ma00090a009 PG 8 WC Polymer Science SC Polymer Science GA NQ241 UT WOS:A1994NQ24100009 ER PT J AU AGARWAL, TK STORAASLI, OO NGUYEN, DT AF AGARWAL, TK STORAASLI, OO NGUYEN, DT TI A PARALLEL-VECTOR ALGORITHM FOR RAPID STRUCTURAL-ANALYSIS ON HIGH-PERFORMANCE COMPUTERS SO COMPUTERS & STRUCTURES LA English DT Article ID CONCURRENT PROCESSING COMPUTERS; SUPERCOMPUTERS; SYSTEMS AB A fast, accurate Choleski method for the solution of symmetric systems of linear equations is presented. This direct method is based on a variable-band storage scheme and takes advantage of column heights to reduce the number of operations in the Choleski factorization. The method employs parallel computation in the outermost DO-loop and vector computation via the 'loop unrolling' technique in the innermost DO-loop. The method avoids computations with zeros outside the column heights, and as an option, zeros inside the band. The close relationship between Choleski and Gauss elimination methods is examined. The minor changes required to convert the Choleski code to a Gauss code to solve non-positive-definite symmetric systems of equations are identified. The results for two large-scale structural analyses performed on supercomputers, demonstrate the accuracy and speed of the method. C1 NASA,LANGLEY RES CTR,DIV STRUCT MECH,HAMPTON,VA 23665. RP AGARWAL, TK (reprint author), OLD DOMINION UNIV,DEPT CIVIL ENGN,NORFOLK,VA 23529, USA. NR 26 TC 4 Z9 4 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 1994 VL 51 IS 5 BP 503 EP 512 DI 10.1016/0045-7949(94)90057-4 PG 10 WC Computer Science, Interdisciplinary Applications; Engineering, Civil SC Computer Science; Engineering GA NW021 UT WOS:A1994NW02100005 ER PT J AU FRANCISCO, JS SANDER, SP LEE, TJ RENDELL, AP AF FRANCISCO, JS SANDER, SP LEE, TJ RENDELL, AP TI STRUCTURES, RELATIVE STABILITIES, AND SPECTRA OF ISOMERS OF HCLO2 SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID MOLECULAR-ORBITAL METHODS; VIBRATIONAL-SPECTRA; CL2O2 AB Ab initio molecular orbital calculations have been carried out to determine the relative stabilities, and the spectroscopy of isomers of HClO2. Two straight-chain isomers, HOOCl and HOClO, and one branched species, HClO2, have been identified as energy minima on the HClO2 potential energy surface. The highest level of calculation performed (CCSD(T)/ANO4) suggests that HOOCl is the lowest energy form. The branched structure is 51.0 kcal mol(-1) higher in energy. The HOClO is 8.3 kcal mol(-1) higher in energy compared to the lowest energy structure. Intense infrared absorptions for HOOCl are calculated at 1399 and 392 cm(-1), at 1186 and 249 cm(-1) for HOClO, and 2168 and 1009 cm(-1) for HClO2. The heat of formation of HOOCl calculated using perturbation theory is similar to that determined using the CCSD(T) level of theory. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. SERC, DARESBURY LAB, WARRINGTON WA4 4AD, CHESHIRE, ENGLAND. RP FRANCISCO, JS (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Rendell, Alistair/A-4883-2008; Lee, Timothy/K-2838-2012 OI Rendell, Alistair/0000-0002-9445-0146; NR 25 TC 52 Z9 52 U1 0 U2 10 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD JUN 2 PY 1994 VL 98 IS 22 BP 5644 EP 5649 DI 10.1021/j100073a012 PG 6 WC Chemistry, Physical SC Chemistry GA NP301 UT WOS:A1994NP30100012 ER PT J AU GILMOUR, S MARDER, SR PERRY, JW CHENG, LT AF GILMOUR, S MARDER, SR PERRY, JW CHENG, LT TI LARGE 2ND-ORDER OPTICAL NONLINEARITIES AND ENHANCED THERMAL STABILITIES IN EXTENDED THIOPHENE-CONTAINING COMPOUNDS SO ADVANCED MATERIALS LA English DT Note C1 DUPONT NEMOURS & CO INC,DEPT CENT RES & DEV,WILMINGTON,DE 19880. CALTECH,BECKMAN INST,CTR MOLEC MAT RESOURCE,PASADENA,CA 91125. RP GILMOUR, S (reprint author), JET PROP LAB,4800 OAK GROVE DR,MAIL STOP 67-201,PASADENA,CA 91109, USA. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 19 TC 32 Z9 32 U1 0 U2 5 PU VCH PUBLISHERS INC PI DEERFIELD BEACH PA 303 NW 12TH AVE, DEERFIELD BEACH, FL 33442-1788 SN 0935-9648 J9 ADV MATER JI Adv. Mater. PD JUN PY 1994 VL 6 IS 6 BP 494 EP 496 DI 10.1002/adma.19940060613 PG 3 WC Chemistry, Multidisciplinary; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter SC Chemistry; Science & Technology - Other Topics; Materials Science; Physics GA NR585 UT WOS:A1994NR58500012 ER PT J AU FEIGENBAUM, EA FRIEDLAND, PE JOHNSON, BB NII, HP SCHORR, H SHROBE, H ENGELMORE, RS AF FEIGENBAUM, EA FRIEDLAND, PE JOHNSON, BB NII, HP SCHORR, H SHROBE, H ENGELMORE, RS TI KNOWLEDGE-BASED SYSTEMS RESEARCH AND APPLICATIONS IN JAPAN, 1992 SO AI MAGAZINE LA English DT Article AB This article summarizes the findings of a 1992 study of knowledge-based systems research and applications in Japan. Representatives of universities and businesses were chosen by the Japan Technology Evaluation Center to investigate the state of the technology in Japan relative to the United States. The panel's report focused on applications, tools, and research and development in universities and industry and on major national projects. C1 NASA,AMES RES CTR,ARTIFICIAL INTELLIGENCE RES BRANCH,MOFFETT FIELD,CA 94035. ANDERSEN CONSULTING,CHICAGO,IL. PENNY NII GALLERY,MT VIEW,CA. UNIV SO CALIF,INST INFORMAT SCI,LOS ANGELES,CA 90089. MIT,ARTIFICIAL INTELLIGENCE LAB,CAMBRIDGE,MA 02139. STANFORD UNIV,DEPT COMP SCI,HEURIST PROGRAMMING PROJECT,STANFORD,CA 94305. STANFORD UNIV,SOFTWARE IND RES PROJECT,STANFORD,CA 94305. RP FEIGENBAUM, EA (reprint author), STANFORD UNIV,KNOWLEDGE SYST LAB,STANFORD,CA 94305, USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 SN 0738-4602 J9 AI MAG JI AI Mag. PD SUM PY 1994 VL 15 IS 2 BP 29 EP 43 PG 15 WC Computer Science, Artificial Intelligence SC Computer Science GA NR506 UT WOS:A1994NR50600010 ER PT J AU GROLEAU, N AF GROLEAU, N TI MODEL-BASED SCIENTIFIC DISCOVERY - A STUDY IN-SPACE BIOENGINEERING SO AI MAGAZINE LA English DT Note RP GROLEAU, N (reprint author), NASA,AMES RES CTR,ARTIFICIAL INTELLIGENCE RES BRANCH,MOFFETT FIELD,CA 94035, USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ARTIFICIAL INTELL PI MENLO PK PA 445 BURGESS DRIVE, MENLO PK, CA 94025-3496 SN 0738-4602 J9 AI MAG JI AI Mag. PD SUM PY 1994 VL 15 IS 2 BP 89 EP 91 PG 3 WC Computer Science, Artificial Intelligence SC Computer Science GA NR506 UT WOS:A1994NR50600016 ER PT J AU DEANE, AE MAVRIPLIS, C AF DEANE, AE MAVRIPLIS, C TI LOW-DIMENSIONAL DESCRIPTION OF THE DYNAMICS IN SEPARATED FLOW PAST THICK AIRFOILS SO AIAA JOURNAL LA English DT Article ID LAMINAR; ORDER; WAKE AB Results are presented for the numerical simulation of unsteady viscous incompressible flow past thick airfoils. Specifically, flow past a NACA 4424 at an angle of attack of 2.5 deg and Reynolds numbers in the range of 1700-4000 has been simulated using the spectral element method. At these conditions the flow is separated and an unsteady wake is formed. Application of the method of empirical eigenfunctions reveals the structure of the most energetic components of the flow. These are found to occur in pairs that, through phase exchange, are responsible for the vortex shedding. A set of ordinary differential equations is obtained for the amplitudes of these eigenfunctions by a Galerkin projection of the Navier-Stokes equations. The solutions of the model system are compared with the full simulation. The work is of relevance to the transition process and observed routes to chaos in airfoil wakes. C1 GEORGE WASHINGTON UNIV,WASHINGTON,DC 20052. RP DEANE, AE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 13 TC 14 Z9 14 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 1994 VL 32 IS 6 BP 1222 EP 1227 DI 10.2514/3.12123 PG 6 WC Engineering, Aerospace SC Engineering GA NQ331 UT WOS:A1994NQ33100015 ER PT J AU GARTENBERG, E WEINSTEIN, LM LEE, EE AF GARTENBERG, E WEINSTEIN, LM LEE, EE TI AERODYNAMIC INVESTIGATION WITH FOCUSING SCHLIEREN IN A CRYOGENIC WIND-TUNNEL SO AIAA JOURNAL LA English DT Article AB A flow visualization study was performed using a focusing schlieren system in the 0.3 m Transonic Cryogenic Tunnel at NASA Langley Research Center. The system proved to be a useful flow visualization tool for flows as low as M = 0.4. This study marked the first verification of the focusing schlieren technique in a major subsonic/transonic wind tunnel and the first time that high-quality, detailed pictures of high-Reynolds-number flows were obtained in a cryogenic wind tunnel. This test was part of a development program to implement instrumentation techniques in cryogenic wind tunnels, with the ultimate aim to use them in the National Transonic Facility. C1 NASA,LANGLEY RES CTR,EXPTL FLOW PHYS BRANCH,HAMPTON,VA 23681. NASA,LANGLEY RES CTR,HIGH REYNOLDS NUMBER AERODYNAM BRANCH,HAMPTON,VA 23681. RP GARTENBERG, E (reprint author), OLD DOMINION UNIV,DEPT MECH ENGN & MECH,NORFOLK,VA 23529, USA. NR 5 TC 9 Z9 9 U1 1 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 JUN PY 1994 VL 32 IS 6 BP 1242 EP 1249 DI 10.2514/3.12126 PG 8 WC Engineering, Aerospace SC Engineering GA NQ331 UT WOS:A1994NQ33100018 ER PT J AU NOOR, AK KIM, YH PETERS, JM AF NOOR, AK KIM, YH PETERS, JM TI TRANSVERSE-SHEAR STRESSES AND THEIR SENSITIVITY COEFFICIENTS IN MULTILAYERED COMPOSITE PANELS SO AIAA JOURNAL LA English DT Article ID LAMINATED PLATES; PREDICTION; ELEMENTS AB A computational procedure is presented for the accurate determination of transverse shear stresses and their sensitivity coefficients in flat multilayered composite panels subjected to mechanical and thermal loads. The sensitivity coefficients measure the sensitivity of the transverse shear stresses to variations in the different lamination and material parameters of the panel. The panel is discretized by using either a three-field mixed finite element model based on a two-dimensional first-order shear deformation plate theory or a two-field degenerate solid element with each of the displacement components having a linear variation throughout the thickness of the laminate. The evaluation of transverse shear stresses can be conveniently divided into two phases. The first phase consists of using a superconvergent recovery technique for evaluating the in-plane stresses in the different layers. In the second phase, the transverse shear stresses are evaluated by using piecewise integration, in the thickness direction, of the three-dimensional equilibrium equations. The same procedure is used for evaluating the sensitivity coefficients of the transverse shear stresses. The effectiveness of the computational procedure is demonstrated by means of numerical examples of multilayered cross-ply panels subjected to transverse loading, uniform temperature change, and uniform temperature gradient through the thickness of the panel. In each case the standard of comparison is taken to be the exact solution of the three-dimensional thermoelasticity equations of the panel. RP NOOR, AK (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR COMP STRUCT TECHNOL,HAMPTON,VA 23681, USA. NR 21 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 JUN PY 1994 VL 32 IS 6 BP 1259 EP 1269 DI 10.2514/3.12128 PG 11 WC Engineering, Aerospace SC Engineering GA NQ331 UT WOS:A1994NQ33100020 ER PT J AU PRASAD, CB AMBUR, DR STARNES, JH AF PRASAD, CB AMBUR, DR STARNES, JH TI RESPONSE OF LAMINATED COMPOSITE PLATES TO LOW-SPEED IMPACT BY DIFFERENT IMPACTORS SO AIAA JOURNAL LA English DT Article; Proceedings Paper CT AIAA/ASME/ASCE/AHS/ASC 34th Structures, Structural Dynamics, and Materials Conference CY APR 19-21, 1993 CL LA JOLLA, CA SP AMER INST AERONAUT & ASTRONAUT, ASME, ASCE, AHS, ASC AB An analytical procedure has been developed to determine the transient response of simply supported, rectangular laminated composite plates subjected to impact loads from airgun-propelled or dropped-weight impactors. A first-order shear deformation theory has been included in the analysis to represent properly any local short-wavelength transient bending response. The impact force has been modeled as a locally distributed load with a cosine-cosine distribution. A double Fourier series expansion and the Timoshenko small increment method have been used to determine the contact force, out-of-plane deflections, and in-plane strains and stresses at any plate location due to an impact force at any plate location. The results of experimental and analytical studies are compared for quasi-isotropic laminates. The results indicate the importance of including transverse shear deformation effects in the analysis for predicting the response of laminated plates subjected to both airgun-propelled and dropped-weight impactors. The results also indicate that plate boundary conditions influence the axial strains more significantly than the contact force for a dropped-weight impactor. The results of parametric studies identify a scaling approach based on impactor momentum that may account for the differences in the responses of plates impacted by airgun-propelled or dropped-weight impactors. C1 NASA,LANGLEY RES CTR,AIRCRAFT STRUCT BRANCH,HAMPTON,VA 23681. RP PRASAD, CB (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23666, USA. NR 14 TC 28 Z9 28 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 JUN PY 1994 VL 32 IS 6 BP 1270 EP 1277 DI 10.2514/3.12129 PG 8 WC Engineering, Aerospace SC Engineering GA NQ331 UT WOS:A1994NQ33100021 ER PT J AU KORIVI, VM TAYLOR, AC HOU, GW NEWMAN, PA JONES, HE AF KORIVI, VM TAYLOR, AC HOU, GW NEWMAN, PA JONES, HE TI SENSITIVITY DERIVATIVES FOR 3-DIMENSIONAL SUPERSONIC EULER CODE USING INCREMENTAL ITERATIVE STRATEGY SO AIAA JOURNAL LA English DT Note C1 NASA,LANGLEY RES CTR,DIV FLUID MECH COMPUTAT SCI BRANCH,HAMPTON,VA 23681. RP KORIVI, VM (reprint author), OLD DOMINION UNIV,DEPT MECH ENGN,NORFOLK,VA 23529, USA. NR 6 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1994 VL 32 IS 6 BP 1319 EP 1321 DI 10.2514/3.12136 PG 3 WC Engineering, Aerospace SC Engineering GA NQ331 UT WOS:A1994NQ33100028 ER PT J AU CHUBB, DL CALFO, FD MCCONLEY, MW MCMASTER, MS AFJEH, AA AF CHUBB, DL CALFO, FD MCCONLEY, MW MCMASTER, MS AFJEH, AA TI GEOMETRY OF THIN LIQUID SHEET FLOWS SO AIAA JOURNAL LA English DT Note ID INSTABILITY C1 PRINCETON UNIV,AEROSP ENGN BRANCH,PRINCETON,NJ 08544. UNIV TOLEDO,DEPT MECH ENGN,TOLEDO,OH 43606. RP CHUBB, DL (reprint author), NASA,LEWIS RES CTR,PHOTOVOLTAICS BRANCH,CLEVELAND,OH 44135, USA. NR 17 TC 5 Z9 6 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD JUN PY 1994 VL 32 IS 6 BP 1325 EP 1328 DI 10.2514/3.12139 PG 4 WC Engineering, Aerospace SC Engineering GA NQ331 UT WOS:A1994NQ33100031 ER PT J AU CONVERTINO, VA DOERR, DF LUDWIG, DA VERNIKOS, J AF CONVERTINO, VA DOERR, DF LUDWIG, DA VERNIKOS, J TI EFFECT OF SIMULATED MICROGRAVITY ON CARDIOPULMONARY BAROREFLEX CONTROL OF FOREARM VASCULAR-RESISTANCE SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE BEDREST; CENTRAL VENOUS PRESSURE; BLOOD VOLUME; BAROREFLEX SENSITIVITY ID CENTRAL VENOUS-PRESSURE; BODY NEGATIVE-PRESSURE; VASOCONSTRICTOR RESPONSES; VOLUME; HUMANS; REDUCTIONS; LBNP; BED AB The stimulus-response characteristics of cardiopulmonary baroreflex control of forearm vascular resistance (FVR) were studied in 11 healthy men before and after 7 days of 6 degrees head-down bedrest to test the hypothesis that microgravity alters this reflex response. We assessed the relationship between stimulus [changes in central venous pressure (Delta CVP)] and reflex response (Delta FVR) during unloading of cardiopulmonary baroreceptors with lower body negative pressure (LBNP; 0 to -20 mmHg). Delta CVP during bedrest and LBNP was estimated from peripheral vein pressures in the dependent right arm. Compared with prebedrest baseline, plasma volume and estimated CVP were decreased by 13 and 33%, respectively, at 7 days of bedrest. Progressive reflex forearm vasoconstriction occurred in response to graded reductions in estimated CVP during LBNP, and Delta FVR per unit Delta CVP was doubled after bedrest. The increase in sensitivity of the cardiopulmonary baroreflex control of FVR was related to reduced circulating blood volume, suggesting that enhanced peripheral vasoconstriction in individuals adapted to microgravity can be attributed, in part, to hypovolemia. In addition, microgravity appears to alter the stimulus for cardiopulmonary baroreceptors to a lower operational range of CVP, suggesting the possibility of chronic resetting. C1 UNIV N CAROLINA,DEPT MATH & STAT,GREENSBORO,NC 27412. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899. RP CONVERTINO, VA (reprint author), AL AOCY,DIV CLIN SCI,PHYSIOL RES BRANCH,2507 KENNEDY CIRCLE,BROOKS AFB,TX 78235, USA. NR 32 TC 71 Z9 72 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0002-9513 J9 AM J PHYSIOL JI Am. J. Physiol. PD JUN PY 1994 VL 266 IS 6 BP R1962 EP R1969 PN 2 PG 8 WC Physiology SC Physiology GA NV810 UT WOS:A1994NV81000087 ER PT J AU KENNEDY, CA CARPENTER, MH AF KENNEDY, CA CARPENTER, MH TI SEVERAL NEW NUMERICAL-METHODS FOR COMPRESSIBLE SHEAR-LAYER SIMULATIONS SO APPLIED NUMERICAL MATHEMATICS LA English DT Article ID FINITE-DIFFERENCE SCHEMES; MODIFIED WKL ALGORITHM; MIXING LAYER; ORDER; STABILITY; EQUATIONS; APPROXIMATIONS; CLASSIFICATION; CONVERGENCE; GASDYNAMICS AB An investigation is conducted of several numerical schemes for use in the computation of two-dimensional, spatially evolving, laminar, variable-density compressible shear layers. Schemes with various temporal accuracies and arbitrary spatial accuracy for both inviscid and viscous terms are presented and analyzed. All integration schemes make use of explicit or compact finite-difference derivative operators. Three classes of schemes are considered: an extension of MacCormack's original second-order temporally accurate method, a new third-order temporally accurate variant of the coupled space-time schemes proposed by Rusanov and by Kutler et al. (RKLW), and third- and fourth-order Runge-Kutta schemes. The RKLW scheme offers the simplicity and robustness of the MacCormack schemes and gives the stability domain and the nonlinear third-order temporal accuracy of the Runge-Kutta method. In each of the schemes, stability and formal accuracy are considered for the interior operators on the convection-diffusion equation U(t) + aU(x) = a(v)U(xx) for which a and alpha(v) are constant. Both spatial and temporal accuracies are verified on the equation U(t) = [b(x)U(x)]x, as well as on U(t) + F(x) = 0. Numerical boundary treatments of various orders of accuracy are chosen and evaluated for asymptotic stability. Formally accurate boundary conditions are derived for explicit sixth-order, pentadiagonal sixth-order, and explicit, tridiagonal, and pentadiagonal eighth-order central-difference operators when used in conjunction with Runge-Kutta integrators. Damping of high wavenumber, nonphysical information is accomplished for all schemes with the use of explicit filters, derived up to sixth order on the boundaries and twelfth order in the interior. Several schemes are used to compute variable-density compressible shear layers, where regions of large gradients of flowfield variables arise near and away from the shear-layer centerline. Results indicate that in the present simulations, the effects of differences in temporal and spatial accuracy between the schemes were less important than the filtering effects. Extended MacCormack schemes were very robust, but were inefficient because of restrictive CFL limits. The third-order temporally accurate RKLW schemes were less dissipative, but had shorter run times. Runge-Kutta integrators did not possess sufficient dissipation to be useful candidates for the computation of variable-density compressible shear layers at the levels of resolution used in the current work. C1 NASA,LANGLEY RES CTR,MS-156,HAMPTON,VA 23681. UNIV CALIF SAN DIEGO,DEPT APPL MECH & ENGN SCI,LA JOLLA,CA 92093. NR 61 TC 234 Z9 238 U1 0 U2 12 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 JUN PY 1994 VL 14 IS 4 BP 397 EP 433 DI 10.1016/0168-9274(94)00004-2 PG 37 WC Mathematics, Applied SC Mathematics GA NV285 UT WOS:A1994NV28500003 ER PT J AU OWEN, WM YEOMANS, DK AF OWEN, WM YEOMANS, DK TI THE OVERLAPPING PLATES METHOD APPLIED TO CCD OBSERVATIONS OF 243-IDA SO ASTRONOMICAL JOURNAL LA English DT Article ID ASTROMETRY AB The overlapping plates method has been applied to crossing-point CCD observations of minor planet 243 Ida to produce absolute position measurements precise to better than 0.1'' and differential position measurements precise to better than 0.06''. Although these observations numbered only 17 out of the 520 that produced the final ground-based Ida ephemeris for the Galileo spacecraft flyby, their inclusion decreased Ida's downtrack error from 78 to 60 km and its out-of-plane error from 58 to 44 km. RP OWEN, WM (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 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 0004-6256 J9 ASTRON J JI Astron. J. PD JUN PY 1994 VL 107 IS 6 BP 2295 EP 2298 DI 10.1086/117037 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NN596 UT WOS:A1994NN59600034 ER PT J AU HABING, HJ TIGNON, J TIELENS, AGGM AF HABING, HJ TIGNON, J TIELENS, AGGM TI CALCULATIONS OF THE OUTFLOW VELOCITY OF ENVELOPES OF COOL GIANTS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, AGB, CIRCUMSTELLAR MATTER, MASS LOSS ID DUST-DRIVEN WINDS; MASS-LOSS RATE; OH-IR STARS; CIRCUMSTELLAR ENVELOPES; RADIATION PRESSURE; AGB STARS; INTERFEROMETRIC OBSERVATIONS; STELLAR ATMOSPHERES; GALACTIC-CENTER; EVOLUTION AB We study the transfer of momentum from photons to dust grains to (molecular) gas in the outflow around cool giants (carbon-stars, Mira variables and OH/IR stars) beyond the radius where the dust grains condense. The problem is circular: radiation pressure determines the outflow velocity of the dust and thus also the dust density; on the other hand the dust density determines, via radiative transfer effects, the spectrum of the photons and thus the effective radiation pressure. This circular problem is solved by a rapidly converging iterative procedure. The gas outflow velocity at large distances, v(out), is a function of the stellar luminosity, L*, of the dust-to-gas ratio, delta, of the mass loss rate, M, and of the radius of the dust grain, a: v(out) is-proportional-to L*0.3delta0.5f , where f is-proportional-to (M /a)1.0 for M < 10(-7) M./yr and f is-proportional-to (M/a)0.04 for M > 10(-5) M./yr: for stars with large mass loss rates, such as OH/IR stars, v(out) does not depend on M nor on the grain radius, a. The fact that v(out)-a quantity that can be measured accurately and easily-depends rather strongly on delta opens the possibility to measure the dust-to-gas ratio in 0-rich stars, such as OH/IR stars; this ratio is probably indicative of the primordial stellar abundance of silicium. The largest outflow velocities are predicted for carbon stars, and this is caused by the slower decrease in photon absorption cross section towards longer wavelengths. We compare our predictions with observed properties of a large sample of OH/IR stars and of Miras and find a good qualitative and quantitative agreement. We confirm a conclusion by Wood et al. (1993) that very luminous OH/IR stars in the Large Magellanic Cloud owe their low outflow velocity to the low dust-to-gas ratio, a consequence of the low metallicity of the LMC. Similarly we consider a sample of about 100 OH/IR stars within 200 pc from the galactic center that has an average B luminosity and an uncommonly high value of v(out); we conclude that these stars are probably very metal rich, perhaps n more than the stars in the Baade window studied by Rich (1990). C1 ECOLE NORMALE SUPER, F-75231 PARIS 05, FRANCE. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP HABING, HJ (reprint author), STERREWACHT, POB 9513, 2300 RA LEIDEN, NETHERLANDS. NR 46 TC 125 Z9 125 U1 0 U2 2 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 1994 VL 286 IS 2 BP 523 EP 534 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NR309 UT WOS:A1994NR30900028 ER PT J AU GRUN, E GUSTAFSON, B MANN, I BAGUHL, M MORFILL, GE STAUBACH, P TAYLOR, A ZOOK, HA AF GRUN, E GUSTAFSON, B MANN, I BAGUHL, M MORFILL, GE STAUBACH, P TAYLOR, A ZOOK, HA TI INTERSTELLAR DUST IN THE HELIOSPHERE SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE INTERPLANETARY MEDIUM; ISM, DUST; ISM, KINEMATICS AND DYNAMICS ID INTER-PLANETARY; SOLAR-SYSTEM; GRAINS; PARTICLES; JUPITER; SPACE AB A flow of mum-sized interstellar grains has been identified with the Ulysses dust detector in the outer solar system at about 5 AU from the Sun. The observed flux is 1.5 10(-4) m-2 s-1 of particles of mean mass 3 10(-13) g, which corresponds to a mass flux of 5 10(-17) g m-2 s-1. The particles on hyperbolic trajectories have radiants which are compatible with the flow of interstellar gas, although some velocity dispersion occurs. The grains are on average a factor 30 more massive than the classical interstellar grains which cause stellar extinction. However, these smaller grains have not been detected by Ulysses. It is demonstrated that radiation pressure and interaction of the charged grains with the interplanetary magnetic field prevent these small grains from penetrating down to the distance of Ulysses. The spatial density of interstellar grains is compatible with zodiacal light observations. Some consequences arising from the existence of big grains in the interstellar medium are discussed. C1 UNIV FLORIDA, DEPT ASTRON, GAINESVILLE, FL 32611 USA. MAX PLANCK INST AERON, D-37189 KATLENBURG DUHM, GERMANY. MAX PLANCK INST EXTRATERR PHYS, D-85740 GARCHING, GERMANY. UNIV KENT, SPACE SCI UNIT, CANTERBURY CT2 7NR, KENT, ENGLAND. NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP GRUN, E (reprint author), MAX PLANCK INST KERNPHYS, SAUPFERCHECKWEG 1, D-69117 HEIDELBERG, GERMANY. RI Gustafson, Bo/B-9526-2011 NR 50 TC 174 Z9 174 U1 0 U2 3 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 0004-6361 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD JUN PY 1994 VL 286 IS 3 BP 915 EP 924 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NT510 UT WOS:A1994NT51000030 ER PT J AU BAKES, ELO TIELENS, AGGM AF BAKES, ELO TIELENS, AGGM TI THE PHOTOELECTRIC HEATING MECHANISM FOR VERY SMALL GRAPHITIC GRAINS AND POLYCYCLIC AROMATIC-HYDROCARBONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; ISM, GENERAL; ISM, MOLECULES; MOLECULAR PROCESSES ID PHOTODISSOCIATION REGIONS; INTERSTELLAR GRAINS; GAS; EMISSION; MODEL; METAL AB We have theoretically modeled the gas heating associated with the photoelectric ejection of electrons from a size distribution of interstellar carbon grains which extends into the molecular domain. We have considered a wide range of physical conditions for the interstellar gas (1 < G0 < 10(5), with G0 being the intensity of the incident far-UV field in units of the Habing interstellar radiation field; 2.5 x 10(-3) < n(e) < 75 cm-3, with n(e) being the electron density; 10 < T < 10,000 K, with T being the gas temperature). The results show that about half of the heating is due to grains less than 1500 C atoms (< 15 angstrom). The other half originates in somewhat larger grains (1500-4.5 x 10(5) C atoms; 15 < a < 100 angstrom). While grains larger than this do absorb about half of the available far-UV photons, they do not contribute appreciably to the gas heating. This strong dependence of gas heating on size results from the decrease in yield and from the increased grain charge (hence larger Coulomb losses) with increasing grain size. We have determined the net photoelectric heating rate and evaluated a simple analytical expression for the heating efficiency, dependent only on G0, T, and n(e). This expression is accurate to 3% over the whole parameter range and is valid up to gas temperatures of 10(4) K, at which point the dominant gas-dust heat exchange mechanism becomes the recombination of electrons with grains rather than photoelectric ejection. The calculated heating efficiency for neutral grains is in good agreement with that derived from observations of the diffuse interstellar clouds. Our results also agree well with the FIRAS observations on COBE. Finally, our photoelectric heating efficiency is compared to previous studies. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP BAKES, ELO (reprint author), PRINCETON UNIV OBSERV,PEYTON HALL,PRINCETON,NJ 08544, USA. NR 42 TC 450 Z9 453 U1 1 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD JUN 1 PY 1994 VL 427 IS 2 BP 822 EP 838 DI 10.1086/174188 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NN739 UT WOS:A1994NN73900026 ER PT J AU COLGAN, SWJ HAAS, MR ERICKSON, EF LORD, SD HOLLENBACH, DJ AF COLGAN, SWJ HAAS, MR ERICKSON, EF LORD, SD HOLLENBACH, DJ TI DAY-640 INFRARED LINE AND CONTINUUM MEASUREMENTS - DUST FORMATION IN SN-1987A SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; INFRARED, ISM, CONTINUUM; INFRARED, ISM, LINES AND BANDS; SUPERNOVAE, INDIVIDUAL (SN-1987A) ID BOLOMETRIC LIGHT-CURVE; SUPERNOVA 1987A; SN 1987A; FE-II; NEUTRON-STAR; EMISSION; SIMULATIONS; VELOCITY; NICKEL; HYDRODYNAMICS AB We have measured day 640-645 line and continuum spectra of [Ni II] 6.6 mum, [Ne II] 12.8 mum (line emission was not detected), and [Fe II] 17.9 and 26.0 mum from SN 1987A. The high velocity feature at upsilon(HVF) approximately 3900 km s-1 found in both of our day 410 [Fe II] spectra is again detected in the day 640 [Ni II] spectrum, although the signal-to-noise of the day 640 [Fe II] spectra is insufficient to show this feature. The continuum fluxes provide clear evidence for the formation of dust between day 410 and day 640 and are best fitted by a graybody spectrum with a temperature of 342 +/- 17 K at day 640 and a surface area corresponding to a minimum dust velocity upsilon(dust) = 1910 +/- 170 km s-1. Optically thin dust emissivity laws proportional to lambda-1 or lambda-2 are inconsistent with the data. Either the dust grains are large (radius a much greater than 4 mum) and radiate like individual blackbodies, or else they are located in clumps optically thick in the 6-26 mum range. The [Ni ii] 6.6 mum line flux yields a minimum Ni+ mass of 5.8 +/- 1.6 x 10(-4) M., and a Ni/Fe abundance ratio of 0.06 +/- 0.02, equal to the solar value. The ratio of the two [Fe II] line profiles implies a gas temperature 2600 +/- 700 K, a drop of 1800 +/- 800 K from our day 410 measurement. The [Fe II] 26.0 mum line flux has decreased by a factor of 2 and the day 640 [Ni II] profile is blueshifted by -440 +/- 270 km s-1, relative to observations before day 500. We show that the decrease in the [Fe II] flux and the blueshift are not produced by a decrease in electron scattering optical depth, electron density, or temperature, but rather are probably due to obscuration by the same dust which produces the infrared continuum. This supports the interpretation that the dust spectrum is produced by optically thick clumps. We discuss possible explanations for the discrepancy between the mass of Fe+ detected and the total iron mass required to power the light curve. The decrease in the [Fe II] fluxes relative to the decrease required to account for the blueshifts of optical lines from non-iron-group elements and the similarity between upsilon(dust) and the Ni+ expansion velocity imply a spatial association between the dust clumps and the iron-group elements. In addition, the larger blueshift observed for the near and far-infrared, heavy metal transitions relative to non-iron-group lines suggests that the iron-group elements are somewhat segregated from lighter elements such as the Mg0 and O0 responsible for shorter wavelength lines. We speculate that FeS may be an important constituent of the dust. A comparison of our line profiles with radiative transfer models shows that while power law and exponential density distributions yield reasonable fits to the data, polytrope distributions provided significantly worse agreement. The best fits require a substantial fraction of the iron to be undetectable, and are consistent with maximum expansion velocities of upsilon(max) approximately 3000 km s-1. C1 ETI INST,MOFFETT FIELD,CA. CALTECH,IPAC,PASADENA,CA 91125. RP COLGAN, SWJ (reprint author), NASA,AMES RES CTR,MS2456,MOFFETT FIELD,CA 94035, USA. RI Colgan, Sean/M-4742-2014 NR 82 TC 47 Z9 47 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 1994 VL 427 IS 2 BP 874 EP 888 DI 10.1086/174193 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NN739 UT WOS:A1994NN73900031 ER PT J AU WOLFIRE, MG CHURCHWELL, E AF WOLFIRE, MG CHURCHWELL, E TI CIRCUMSTELLAR DUST EMISSION MODELS SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; DUST, EXTINCTION; RADIATIVE TRANSFER; STARS, EARLY-TYPE ID H-II REGIONS; FAR-INFRARED OBSERVATIONS; AURIGA MOLECULAR CLOUD; EMBEDDED YOUNG STARS; OPTICAL-PROPERTIES; ULTRAVIOLET EXTINCTION; INTERSTELLAR GRAPHITE; SILICATE GRAINS; HIGH-RESOLUTION; PROTOSTARS AB We present the wavelength-dependent absorption coefficient kappa(lambda), the scattering coefficient sigma(lambda), the albedo omega(lambda), and the average cosine of the scattering phase function g(lambda) between 0.0912 mum and 1000 mum for four interstellar medium grain models. These grain models are used in a radiation transfer code to calculate the properties of dust shells surrounding a newly formed O star. For each shell model a distribution of 25 grain sizes and two compositions were used in our calculations. The spectral type of the central star (O6 ZAMS), the geometry (shell), and circumstellar density distribution (constant) are the same in all models, so that different model predictions result entirely from differences in grain properties. For each grain type the models predict the emergent spectral energy distribution with wavelength, the optical depth with wavelength, and the mean dust temperature with distance from the central star. In addition, we find the emitted envelope flux (total flux minus the direct stellar contribution) included within an angular radius theta for several wavelengths between 2.2 mum and 100 mum. It is found that large differences in the emitted spectrum can occur when grains with different optical constants and size distributions are used. C1 UNIV WISCONSIN,WASHBURN OBSERV,MADISON,WI 53706. RP WOLFIRE, MG (reprint author), NASA,AMES RES CTR,MAIL STOP 245-3,MOFFETT FIELD,CA 94035, USA. NR 40 TC 34 Z9 34 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 1994 VL 427 IS 2 BP 889 EP 897 DI 10.1086/174194 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NN739 UT WOS:A1994NN73900032 ER PT J AU SOFIA, S HEAPS, W TWIGG, LW AF SOFIA, S HEAPS, W TWIGG, LW TI THE SOLAR DIAMETER AND OBLATENESS MEASURED BY THE SOLAR DISK SEXTANT ON THE 1992 SEPTEMBER 30 BALLOON FLIGHT SO ASTROPHYSICAL JOURNAL LA English DT Article DE BALLOONS; INSTRUMENTATION, MISCELLANEOUS; SUN, FUNDAMENTAL PARAMETERS ID LATITUDE; SUN AB This paper reports the results of a balloon flight of the Solar Disk Sextant on 1992 September 30. This was the first flight in which the SDS used a wedge assembly fabricated by molecular contact in order to eliminate the wedge angle variations observed in previous flights. The instrument performed as designed. The main results obtained are values of the solar diameter for a number of discrete heliocentric latitudes, and the solar oblateness. The accuracy of the diameter values is better than 0.2'', whereas the precision is approximately 1-2 mas. The equatorial solar diameter, at 1 AU, was 1919.06'' +/- 0.12'', and the oblateness epsilon = 8.63 +/- 0.88 x 10(-6). C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. APPL RES CORP,LANDOVER,MD 20785. RP SOFIA, S (reprint author), YALE UNIV,CTR SOLAR & SPACE RES,POB 208101,NEW HAVEN,CT 06520, USA. NR 24 TC 53 Z9 54 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 1994 VL 427 IS 2 BP 1048 EP 1052 DI 10.1086/174211 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NN739 UT WOS:A1994NN73900049 ER PT J AU GEHRELS, N CHIPMAN, E KNIFFEN, D AF GEHRELS, N CHIPMAN, E KNIFFEN, D TI THE COMPTON-GAMMA-RAY-OBSERVATORY SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article; Proceedings Paper CT INTEGRAL Workshop on the Multiwavelength Approach to Gamma-Ray Astronomy CY FEB 02-05, 1993 CL LES DIABLERETS, SWITZERLAND SP INT GAMMA RAY ASTROPHYS LAB DE ARTIFICIAL SATELLITES, SPACE PROBES; TELESCOPES ID SCINTILLATION SPECTROMETER EXPERIMENT; INSTRUMENT DESCRIPTION; MAGELLANIC CLOUD; EGRET; RADIATION; SN-1987A; BURSTS; BATSE; DISCOVERY; TELESCOPE AB The Arthur Holly Compton Gamma Ray Observatory (Compton) is the second in NASA's series of Great Observatories. Launched on 1991 April 5, Compton represents a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made. We describe the capabilities of the four scientific instruments, and the observing program of the first 2 years of the mission. Examples of early discoveries by Compton are enumerated, including the discovery that gamma-ray bursts are isotropic but spatially inhomogeneous in their distribution; the discovery of a new class of high-energy extragalactic gamma-ray sources, the gamma-ray AGNs; the discovery of emission from SN 1987A in the nuclear line of Co-57; and the mapping of emission from Al-26 in the ISM near the Galactic center. Future observations will include deep surveys of selected regions of the sky, long-term studies of individual objects, correlative studies of objects at gamma-ray and other energies, a Galactic plane survey at intermediate gamma-ray energies, and improved statistics on gamma-ray bursts to search for small anisotropies. After completion of the all-sky survey, a Guest Investigator program is in progress with guest observers' time share increasing from 30% upward for the later mission phases. C1 HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. COMP SCI CORP,SCI PROGRAMS,GREENBELT,MD 20771. RP GEHRELS, N (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012 NR 65 TC 19 Z9 20 U1 0 U2 1 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 1994 VL 92 IS 2 BP 351 EP 362 DI 10.1086/191978 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NM319 UT WOS:A1994NM31900007 ER PT J AU TEEGARDEN, BJ AF TEEGARDEN, BJ TI A REVIEW OF RECENT RESULTS IN GAMMA-RAY ASTRONOMY OBTAINED FROM HIGH-ALTITUDE BALLOONS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article; Proceedings Paper CT INTEGRAL Workshop on the Multiwavelength Approach to Gamma-Ray Astronomy CY FEB 02-05, 1993 CL LES DIABLERETS, SWITZERLAND SP INT GAMMA RAY ASTROPHYS LAB DE GALAXY, CENTER; GAMMA-RAYS, OBSERVATIONS; SUPERNOVAE, INDIVIDUAL (SN-1987A); X-RAYS, GENERAL ID GALACTIC-CENTER DIRECTION; POSITRON-ANNIHILATION RADIATION; X-RAY; CENTER REGION; SN 1987A; EMISSION; LINE; 1E1740.7-2942; CLOUD AB This paper reviews recent results in gamma-ray astronomy obtained from experiments flown on high-altitude balloons. New generation balloon-borne imaging experiments have produced the first gamma-ray maps of the Galactic center (GC) region. Balloon flights of new gamma-ray spectrometers with improved sensitivity have provided important new information on the G-C annihilation line. For the first time, the narrow 511 keV line as been resolved (FWHM almost-equal-to 3 keV). A very interesting spectral feature at approximately 170 keV has been attributed to backscattered annihilation, probably from the vicinity of a compact object. New results from the CGRO/OSSE and Granat/SIGMA experiments on the annihilation line, when considered together with the recent balloon results, have added greatly to our knowledge and understanding of the origin and distribution of this emission. Balloon-borne instruments have made important measurements of gamma-ray continuum and line emission from SN 1987A. The GRIS spectrometer unambiguously resolved the 847 and 1238 keV line emission from radioactive Co-56 synthesized during the explosion. This data indicated that simple spherically symmetric and homogeneous models did not provide an adequate description of the expanding SN shell. RP TEEGARDEN, BJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 43 TC 5 Z9 5 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 1994 VL 92 IS 2 BP 363 EP 368 DI 10.1086/191979 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NM319 UT WOS:A1994NM31900008 ER PT J AU RAMATY, R SKIBO, JG LINGENFELTER, RE AF RAMATY, R SKIBO, JG LINGENFELTER, RE TI GALACTIC 0.511 MEV LINE EMISSION SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article; Proceedings Paper CT INTEGRAL Workshop on the Multiwavelength Approach to Gamma-Ray Astronomy CY FEB 02-05, 1993 CL LES DIABLERETS, SWITZERLAND SP INT GAMMA RAY ASTROPHYS LAB DE GALAXY, CENTER; GAMMA-RAYS, OBSERVATIONS ID POSITRON-ANNIHILATION RADIATION; X-RAY NOVA; CENTER REGION; CENTER DIRECTION; MOLECULAR CLOUD; IRON LINE; 1E1740.7-2942; GALAXY; CONTINUUM; SPECTRUM AB Observations over two decades with various balloon-borne instruments and instruments on HEAO 3, SMM, and CGRO have revealed the existence of strong 0.511 MeV line emission from the direction of the Galactic center. We have attempted to fit the spatial distribution of this emission with distributions of various Galactic constituents, but found that none of these distributions alone could fit the data. Of the assumed distributions, those of Galactic novae and hot (10(8) K) plasma are the most strongly peaked at the Galactic center. But we found that the 0.511 MeV line emission is even more strongly peaked. This new result is the direct consequence of the analysis of recent data obtained with the OSSE instrument on CGRO. We have thus considered two-component models consisting of an enhanced central Galactic component superposed on a Galactic plane component given by any one of our previously assumed distributions. For the central Galactic component we take either a single point source at the location of the source of annihilation radiation 1E 1740.7-2942 or an extended spheroidal distribution of several hundred parsecs in size. We find acceptable fits in both cases. We suggest that this additional component of the emission from the Galactic center region is due to positrons produced near one or more black holes. Such a component was also suggested by the variability of the 0.511 MeV line flux observed with balloon-borne high-resolution detectors. To produce the very narrow line observed by these high-resolution detectors at almost precisely 0.511 MeV the positrons must escape from the vicinity of the holes and annihilate in the surrounding interstellar medium. We have reexamined the issue of the time variability of the 0.511 MeV line emission. Although the significance of the variability implied by all of the earlier observations is diminished by a large number of recent OSSE observations which show no variability, the latter measurements merely indicate that the flux remained relatively constant only over a period of about 1 year (1991-1992). Positron production in the Galactic center region by a small number of variable sources would lead to variable 0.511 MeV line emission. The timescale of the variation depends on the density of the gas in which the positrons annihilate. It could be as short as several months if the annihilation is in dense molecular clouds, but would be much longer and essentially undetectable if the positrons annihilate in lower density interstellar gas. C1 UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. UNIV MARYLAND,DEPT PHYS,COLLEGE PK,MD 20742. RP RAMATY, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. NR 55 TC 23 Z9 23 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 1994 VL 92 IS 2 BP 393 EP 399 DI 10.1086/191984 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NM319 UT WOS:A1994NM31900013 ER PT J AU BLOEMEN, H HERMSEN, W SWANENBURG, BN DEVRIES, CP DIEHL, R SCHONFELDER, V STEINLE, H STRONG, AW CONNORS, A MCCONNELL, M MORRIS, D STACY, G BENNETT, K WINKLER, C AF BLOEMEN, H HERMSEN, W SWANENBURG, BN DEVRIES, CP DIEHL, R SCHONFELDER, V STEINLE, H STRONG, AW CONNORS, A MCCONNELL, M MORRIS, D STACY, G BENNETT, K WINKLER, C TI COMPTEL IMAGING OF THE GALACTIC DISK AND THE SEPARATION OF DIFFUSE EMISSION AND POINT SOURCES SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article; Proceedings Paper CT INTEGRAL Workshop on the Multiwavelength Approach to Gamma-Ray Astronomy CY FEB 02-05, 1993 CL LES DIABLERETS, SWITZERLAND SP INT GAMMA RAY ASTROPHYS LAB DE DIFFUSE RADIATION; GAMMA-RAYS, OBSERVATIONS ID GAMMA-RAY EMISSION; RADIATION; SPECTRUM; REGION AB The first MeV image of the inner Galaxy obtained with the COMPTEL telescope aboard the Compton Gamma-Ray Observatory shows a structured ridge of emission along the Galactic equator which probably consists of diffuse radiation and unresolved discrete sources. The intensity distribution of this ridge distinctly differs from the expected distribution for a simple model of the diffuse radiation. Most remarkable are the observed excursions out of the disk, which may hint at the presence of gamma-ray point sources located several degrees away from the mid-plane, but a diffuse origin cannot be excluded. If these are indeed discrete sources, a substantial fraction of the unresolved emission along the disk may not be of diffuse origin, with an ensemble of sources hidden in the observed ridge. C1 MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY. EUROPEAN SPACE TECHNOL CTR,DIV ASTROPHYS,2200 AG NOORDWIJK,NETHERLANDS. NASA,GODDARD SPACE FLIGHT CTR,GSFC,COMPTON OBSERV,CTR SCI SUPPORT,GREENBELT,MD 20771. UNIV NEW HAMPSHIRE,CTR SPACE SCI,DURHAM,NH 03824. LEIDEN OBSERV,LEIDEN,NETHERLANDS. RP BLOEMEN, H (reprint author), SRON LEIDEN,POB 9504,2300 RA LEIDEN,NETHERLANDS. NR 24 TC 73 Z9 73 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 1994 VL 92 IS 2 BP 419 EP 423 DI 10.1086/191988 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA NM319 UT WOS:A1994NM31900017 ER EF