FN Thomson Reuters Web of Science™ VR 1.0 PT J AU CHASNOV, JR AF CHASNOV, JR TI SIMULATION OF THE INERTIAL CONDUCTIVE SUBRANGE SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article; Proceedings Paper CT INTERNATIONAL SYMP ON FLUID MECHANICS OF STIRRING AND MIXING CY AUG 20-24, 1990 CL UNIV CALIF SAN DIEGO, LA JOLLA, CA SP INT UNION THEORET & APPL MECH HO UNIV CALIF SAN DIEGO ID TURBULENCE AB The inertial-conductive subrange spectrum of a passive temperature field of a fluid of small Prandtl number is determined by large-eddy simulation. Results for simulations of both freely decaying and forced turbulence are presented. In the simulations of freely decaying turbulence, a subgrid model is used to simulate a decaying turbulent velocity field with a k -5/3 inertial subrange energy spectrum convecting eight different decaying temperature fields with well-resolved conductive subranges. In the simulations of forced turbulence, a subgrid model is again used to simulate an inertial subrange velocity field; however, the velocity field is now forced at the lowest wave numbers of the simulation, and an external uniform mean temperature gradient is imposed. Statistically stationary velocity and temperature fluctuations are generated. The results of the decaying and forced simulations are in excellent agreement with the Batchelor, Howells, and Townsend (BHT) [J. Fluid Mech. 5, 134 (1959)] k -17/3 spectrum in the far inertial-conductive subrange, whereas significant departures from the BHT spectrum are observed in the near inertial-conductive subrange. RP CHASNOV, JR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 6 TC 3 Z9 3 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD MAY PY 1991 VL 3 IS 5 BP 1164 EP 1168 DI 10.1063/1.858044 PN 2 PG 5 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FL372 UT WOS:A1991FL37200020 ER PT J AU JIMENEZ, J MARTEL, C AF JIMENEZ, J MARTEL, C TI FRACTAL INTERFACES AND PRODUCT GENERATION IN THE 2-DIMENSIONAL MIXING LAYER SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article; Proceedings Paper CT INTERNATIONAL SYMP ON FLUID MECHANICS OF STIRRING AND MIXING CY AUG 20-24, 1990 CL UNIV CALIF SAN DIEGO, LA JOLLA, CA SP INT UNION THEORET & APPL MECH HO UNIV CALIF SAN DIEGO ID TURBULENCE AB The dependence of product generation on Peclet and Reynolds numbers in a numerically simulated, reacting, two-dimensional, temporally growing mixing layer is related theoretically to the fractal dimension of the passive scalar interfaces. This relation is verified using product generation measurements and fractal dimensions derived from the box counting technique. A transition from a low initial dimension to a higher one of approximately 5/3 is identified and shown to be associated to the kinematic distortion of the flow field during the first pairing interaction. It is suggested that the structures responsible for this transition are nondeterministic, nonrandom, inhomogenous fractals. In the range of Schmidt numbers investigated (0.25-4), only the large scales are involved. No further transitions, either in the spectra of the vorticity field or in the mixing behavior, are found for Reynolds numbers up to 90 000. C1 STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP JIMENEZ, J (reprint author), UNIV POLITECN MADRID,SCH AERONAUT,E-28040 MADRID,SPAIN. RI jimenez, javier/A-6691-2008 OI jimenez, javier/0000-0003-0755-843X NR 12 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 0899-8213 J9 PHYS FLUIDS A-FLUID PD MAY PY 1991 VL 3 IS 5 BP 1261 EP 1268 PN 2 PG 8 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FL372 UT WOS:A1991FL37200030 ER PT J AU BUSHNELL, PG BRILL, RW AF BUSHNELL, PG BRILL, RW TI RESPONSES OF SWIMMING SKIPJACK (KATSUWONUS-PELAMIS) AND YELLOWFIN (THUNNUS-ALBACARES) TUNAS TO ACUTE-HYPOXIA, AND A MODEL OF THEIR CARDIORESPIRATORY FUNCTION SO PHYSIOLOGICAL ZOOLOGY LA English DT Article ID VENTILATION; DEVICES; RATES; BLOOD; FISH AB Heart rate and swimming-speed responses to acute hypoxia were measured in skipjack (Katsuwonus pelamis) and yellowfin tunas (Thunnus albacares). Swimming speeds began to increase in both species when O2 tension (Po2) reached approximately 124 mmHg. Bradycardia became significant in both species when Po2 reached approximately 130 mmHg. Heart rate fell with Po2 in yellowfin tuna, but, in skipjack tuna, it increased at the lowest O2 levels reached (89-70 mmHg). Bradycardia occurred in both species despite concomitant increases in swimming speed. A continuous infusion dye dilution system was used to monitor changes in ventilation volume (V(g)) during hypoxia in yellowfin tuna. As Po2 fell, V(g) increased. At the lowest O2 levels (109-90 mmHg), V(g) was 45% higher than during normoxia. Ventilation volume increased despite no concomitant increases in swimming speed. Data from these experiments were used to develop a model capable of predicting O2 demand and delivery, maximum sustainable (i.e., aerobic) swimming speeds, and minimum survivable O2 levels for yellowfin and skipjack tunas. Results from the model indicate that the cardiorespiratory system of tunas is capable of maximum rates of O2 delivery, even at low swimming speeds, that are approximately three times those of other active teleosts. We believe that, because the pelagic environment provides no place to hide and rest following exhaustive activity, the ability of the cardiorespiratory system of tunas to deliver O2 to the tissues at high rates evolved for the rapid repayment of O2 debts rather than to permit exceptionally high sustained swimming speeds. C1 NOAA,NATL MARINE FISHERIES SERV,HONOLULU LAB,SW FISHERIES SCI CTR,2570 DOLE ST,HONOLULU,HI 96822. UNIV HAWAII,JOHN A BURNS SCH MED,DEPT PHYSIOL,HONOLULU,HI 96822. NR 43 TC 62 Z9 62 U1 0 U2 4 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0031-935X J9 PHYSIOL ZOOL JI Physiol. Zool. PD MAY-JUN PY 1991 VL 64 IS 3 BP 787 EP 811 PG 25 WC Physiology; Zoology SC Physiology; Zoology GA FY293 UT WOS:A1991FY29300011 ER PT J AU DELVA, M SCHWINGENSCHUH, K NIEDNER, MB GRINGAUZ, KI AF DELVA, M SCHWINGENSCHUH, K NIEDNER, MB GRINGAUZ, KI TI COMET HALLEY REMOTE PLASMA TAIL OBSERVATIONS AND INSITU SOLAR-WIND PROPERTIES - VEGA-1/2 IMF PLASMA OBSERVATIONS AND GROUND-BASED OPTICAL OBSERVATIONS FROM 1 DECEMBER 1985 TO 1 MAY 1986 SO PLANETARY AND SPACE SCIENCE LA English DT Article ID DISCONNECTION EVENTS; P/HALLEY; RECONNECTION; DYNAMICS; TIME; GAS AB Properties of the interplanetary magnetic field and solar wind plasma are analysed from continuous observations from 1 December 1985 to 1 May 1986 made by the Vega spacecraft (Riedler et al., 1986, Nature 321, 288; Gringauz et al., 1986, Nature 321, 282). Several high speed streams and flare-related shocks are found; the magnetic field sector boundaries are also seen. Many Earth-based observations of disconnection events in the plasma tail of comet Halley are now available and several mechanisms [changes in the solar wind (Jockers, 1985, Astron. Astrophys. Suppl. Ser. 62, 791; 1986, Asteroids, Comets and Meteors II, Reprocentralen HSC, Uppsala), interplanetary magnetic field features, e.g. day-side reconnection (Niedner and Brandt, 1978, Astrophys. J. 223, 665) or night-side reconnection (Russell et al., 1986, J. geophys. Res. 91, 1417)] have been proposed to explain the occurrence of such events. We investigated the correlation between the IMF sector boundaries measured by Vega and the observed disconnection events; such a correlation would support the day-side reconnection explanation. It is found that only in 50% of the considered events does a correlation between these two phenomena exist. For the other cases, a sector boundary of the IMF sweeping over the comet cannot explain the occurrence of disruptions of the main plasma tail. An indication is also seen that density enhancements (e.g. as they occur for high speed streams) in the solar wind are connected with large tail events. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. SPACE RES INST,MOSCOW 117810,USSR. RP DELVA, M (reprint author), AUSTRIAN ACAD SCI,INST SPACE RES,INFFELDGASSE 12,A-8010 GRAZ,AUSTRIA. RI Niedner, Malcolm/E-2244-2012 NR 27 TC 14 Z9 14 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAY PY 1991 VL 39 IS 5 BP 697 EP 708 DI 10.1016/0032-0633(91)90063-G PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FG778 UT WOS:A1991FG77800004 ER PT J AU OWEN, CJ BALOGH, A COWLEY, SWH RICHARDSON, IG TSURUTANI, BT AF OWEN, CJ BALOGH, A COWLEY, SWH RICHARDSON, IG TSURUTANI, BT TI THEORY AND OBSERVATION OF ENERGETIC IONS IN THE LOBES OF THE GEOMAGNETIC TAIL SO PLANETARY AND SPACE SCIENCE LA English DT Article ID PLASMA SHEET; DISTANT MAGNETOTAIL; BOUNDARY-LAYER; NEAR-EARTH; ISEE-3; SUBSTORM; CDAW-8; ASYMMETRIES; BURSTS; RE AB In a recent paper, Owen et al. (1990, Planet. Space Sci. 38, 851) presented a model which attempts to explain the nature of the pitch angle distributions of energetic ions within the lobes of the distant geomagnetic tail. There has, however, been little discussion of the relevant observations in the literature, and the motivation for the above mentioned work was largely based on unpublished observations plus a few examples presented in the paper itself. In this paper we aim to rectify this situation. After briefly reviewing the model and its results, we present energetic (E greater-than-or-equal-to 35 keV) ion data from the ISEE-3 spacecraft obtained during early 1983, when the spacecraft made several traversals of the distant geomagnetic tail (X(GSE) = -230 R(E)). The data demonstrate that during quiet periods in which the spacecraft is continuously located in the tail lobes, the pitch angle distribution is observed to be highly anisotropic, being peaked closely perpendicular to the magnetic field direction, but with a small net flow in the antisunward direction, in agreement with the model results. Further predictions of the model, concerning the variation of the lobe energetic ion distributions with position in the lobes, are compared to observations made as the spacecraft performed a traversal of the lobe. Finally, since the model indicates that a more isotropic distribution should exist in the tail lobe during solar particle events, we present data from such a period for further comparison. In all the above cases, good agreement is demonstrated between the data and the expectations of the model. C1 UNIV LONDON IMPERIAL COLL SCI & TECHNOL,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. CALTECH,JET PROP LAB,PASADENA,CA 91109. RI Owen, Christopher/C-2999-2008; OI Owen, Christopher/0000-0002-5982-4667; Richardson, Ian/0000-0002-3855-3634 NR 22 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 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAY PY 1991 VL 39 IS 5 BP 761 EP 775 DI 10.1016/0032-0633(91)90071-H PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FG778 UT WOS:A1991FG77800012 ER PT J AU JACKSON, TJ ONEILL, PE AF JACKSON, TJ ONEILL, PE TI MICROWAVE EMISSION AND CROP RESIDUES SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SOIL-MOISTURE AB A series of controlled experiments were conducted to determine the significance of crop residues or stubble in estimating the emission of the underlying soil. Observations using truck-mounted L and C band passive microwave radiometers showed that for dry wheat and soybeans the dry residue caused negligible attenuation of the background emission. Green residues, with water contents typical of standing crops, did have a significant effect on the background emission. Results for these green residues also indicated that extremes in plant structure, as created using parallel and perpendicular stalk orientations, can cause very large differences in the degree of attenuation. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP JACKSON, TJ (reprint author), USDA ARS,BELTSVILLE AGR RES CTR,EAST,HYDROL LAB,BLDG 265,RM 205,BELTSVILLE,MD 20705, USA. RI O'Neill, Peggy/D-2904-2013 NR 10 TC 8 Z9 8 U1 0 U2 2 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD MAY PY 1991 VL 36 IS 2 BP 129 EP 136 DI 10.1016/0034-4257(91)90035-5 PG 8 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA FZ863 UT WOS:A1991FZ86300004 ER PT J AU HAAG, TW AF HAAG, TW TI THRUST STAND FOR HIGH-POWER ELECTRIC PROPULSION DEVICES SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB A thrust stand for use with magnetoplasmadynamic (MPD) thrusters operated at powers up to 250 kW steady state has been built and tested. The stand was based on an inverted pendulum configuration which resulted in large displacements and high resolution. Up to 50 mm of deflection was observed under a force of 5 N. This large range of displacement signficantly reduced the effects of facility induced vibrations on thrust measurements. A remotely operated system was provided for in situ calibration of the thrust stand prior to and immediately after data were obtained. Calibrations showed that thrust measurements were linear and repeatable to within a fraction of 1%. Structural distortions of the vacuum facility due to pumpdown were detected with an inclinometer located in the thrust stand base. Slope deviations as small as 10 arcsec could be compensated using a remotely controlled leveling motor. Early problems with magnetically induced tares caused by the thruster discharge current were reduced by rerouting high-current cables to decrease stray fields. Tares due to discharge current were on the order of 26 mN at 3000 A, and those due to an applied field current were 63 mN at 1400 A. The thrust stand was used with a water-cooled, applied field, steady-state MPD device at power levels up to 125 kW. Hot thruster firings as long as 1 h were performed. By precisely maintaining a level thrust stand base, thermal drift was held to about 2% of the full scale reading over this period. The remaining thermal drift could be subtracted from the thrust measurement to further reduce systematic error. Tares caused by the applied magnetic field were similarly removed. By substracting tabulated discharge current magnetic tares, thrust measurement uncertainty was reduced to approximately 2% of the measured value. RP HAAG, TW (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 9 TC 37 Z9 40 U1 0 U2 11 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAY PY 1991 VL 62 IS 5 BP 1186 EP 1191 DI 10.1063/1.1141998 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA FK344 UT WOS:A1991FK34400008 ER PT J AU KELLER, JW TORBERT, RB VANDIVER, J AF KELLER, JW TORBERT, RB VANDIVER, J TI HIGH-SPEED PITCH ANGLE SORTER SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article AB We have developed a high-speed method to compress the two-dimensional angular distribution of space particles gathered by space plasma instrumentation into the pitch angle distribution, where the pitch angle is polar angle with respect to the ambient magnetic field. The pitch angle sorter can handle rates of up to 2 MHz and it is designed to accommodate high angular resolution plasma analyzers that are placed on a rotating spacecraft. This compression is achieved by relying on digitally encoded lookup tables to eliminate all arithmetic operations while applying the high symmetry of this compression to reduce the amount of digital memory. C1 UNIV NEW HAMPSHIRE,DURHAM,NH 03824. VANDIVER ELECTR,HUNTSVILLE,AL 35811. RP KELLER, JW (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. RI Keller, John/I-5097-2013 NR 1 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 0034-6748 J9 REV SCI INSTRUM JI Rev. Sci. Instrum. PD MAY PY 1991 VL 62 IS 5 BP 1353 EP 1355 DI 10.1063/1.1142498 PG 3 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA FK344 UT WOS:A1991FK34400036 ER PT J AU CHOUDHURY, BJ AF CHOUDHURY, BJ TI MULTISPECTRAL SATELLITE DATA IN THE CONTEXT OF LAND SURFACE HEAT-BALANCE SO REVIEWS OF GEOPHYSICS LA English DT Article ID DOWNWARD LONGWAVE RADIATION; INCIDENT SOLAR-RADIATION; NET-RADIATION; SOIL-MOISTURE; POLARIZATION DIFFERENCE; VEGETATION INDEXES; SCATTEROMETER DATA; SPECTRAL INDEXES; PHYSICAL MODEL; CLIMATE CHANGE AB Any realistic study of the Earth's climate must consider thermal interaction between the atmosphere and the land surface. During the past few years, several highly sophisticated models have been developed to describe exchanges of radiation, heat, and momentum between the land surface and the atmosphere at mesoscales and global scales. These models need to be supplemented by high-quality global measurements at varying spatial and temporal scales of physical and biological states of the land surface. Global data sets are needed for surface parameters used to describe the processes and also to initialize and validate the time evolution of surface characteristics predicted by the model. Observations in different spectral bands by instruments on board satellites can provide spatially representative values for some of the fluxes and radiative characteristics of the surface, from which the parameters needed for heat balance modeling have to be derived. Development of these data sets presents considerable difficulty because the relations between radiative and physical characteristics are generally nonlinear and nonunique; the radiative characteristic in any spectral band is generally determined by several physical characteristics. Relationships between different spectral observations can be used to develop hypotheses concerning the relative importance of different land surface parameters determining these observations, which would have to be confirmed by field observations. Satellite observations for visible, near-infrared, infrared, and microwave bands to estimate the fluxes at the surface (radiative, soil, sensible, and latent heat) and surface characteristics (albedo, surface temperature, vegetation parameters, and soil moisture) are presented. Interannual variations of some of these satellite observations are discussed in relation to land surface change. A better understanding needs to be developed regarding the interpretation of infrared temperature observations as they relate to the temperature determined by the heat balance equation. Further study is needed to explore more effective use of remotely sensed data for vegetation in heat balance modeling. RP NASA, GODDARD SPACE FLIGHT CTR, HYDROL SCI BRANCH, GREENBELT, MD 20771 USA. NR 101 TC 40 Z9 40 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 8755-1209 EI 1944-9208 J9 REV GEOPHYS JI Rev. Geophys. PD MAY PY 1991 VL 29 IS 2 BP 217 EP 236 DI 10.1029/91RG02635 PG 20 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FL559 UT WOS:A1991FL55900005 ER PT J AU DIXON, TH AF DIXON, TH TI AN INTRODUCTION TO THE GLOBAL POSITIONING SYSTEM AND SOME GEOLOGICAL APPLICATIONS SO REVIEWS OF GEOPHYSICS LA English DT Article ID PHASE AMBIGUITY RESOLUTION; GPS GEODETIC NETWORK; CASA UNO 88; PLATE MOTION; SOUTHERN-CALIFORNIA; CRUSTAL DEFORMATION; WATER-VAPOR; BASELINE REPEATABILITY; RADIO INTERFEROMETRY; OPERATIONAL ASPECTS AB Receivers equipped to measure dual frequency carrier phase signals from satellites of the Global Positioning System (GPS) have been capable, under special conditions, of determining relative horizontal positions among stations separated by one to a few hundred kilometers with a precision of one to several millimeters since the early 1980s. The major obstacles to making this capability routine, extending it to all parts of the globe, and extending it to longer station separations, have been equipment cost, limitations in the GPS satellite constellation, arduous data analysis, uncertainties in satellite orbits, uncertainties in propagation delays associated with variable tropospheric water vapor, and difficulties in resolving carrier phase cycle ambiguities. Recent improvements have occurred in all these areas. The increasing ease and reduced cost of GPS data acquisition and analysis are having a significant impact on studies of near-fault crustal deformation and earthquake processes, until recently the province of conventional terrestrial geodetic techniques. The enhanced satellite constellation, improved models, and establishment of global tracking networks have extended several millimeters horizontal positioning capability to station separations of 1000 km or more in virtually all parts of the world. This enables study of new classes of tectonic problems that previously were difficult to attack with any geodetic technique. Examples include a complete kinematic description of ongoing crustal deformation in broad, complex continental plate boundary zones, and measurement of relative plate motion at convergent boundaries where global models may be poorly constrained. RP CALTECH, JET PROP LAB, DIV EARTH & PLANETARY SCI, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Wright, Dawn/A-4518-2011 OI Wright, Dawn/0000-0002-2997-7611 NR 142 TC 131 Z9 140 U1 0 U2 13 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 8755-1209 EI 1944-9208 J9 REV GEOPHYS JI Rev. Geophys. PD MAY PY 1991 VL 29 IS 2 BP 249 EP 276 DI 10.1029/91RG00152 PG 28 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FL559 UT WOS:A1991FL55900007 ER PT J AU ROSSOW, WB AF ROSSOW, WB TI WHO KNOWS WHERE THE CLOUDS GO - THE QUESTION IS CRUCIAL TO THE FORECAST OF GLOBAL WARMING SO SCIENCES-NEW YORK LA English DT Article RP ROSSOW, WB (reprint author), NASA,GODDARD INST SPACE STUDIES,CTR GLOBAL PROC,NEW YORK,NY 10025, USA. RI Rossow, William/F-3138-2015 NR 0 TC 0 Z9 0 U1 0 U2 0 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0036-861X J9 SCIENCES JI Sci.-New York PD MAY-JUN PY 1991 VL 31 IS 3 BP 36 EP 41 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FH144 UT WOS:A1991FH14400013 ER PT J AU TALEZER, H AF TALEZER, H TI HIGH DEGREE POLYNOMIAL INTERPOLATION IN NEWTON FORM SO SIAM JOURNAL ON SCIENTIFIC AND STATISTICAL COMPUTING LA English DT Article DE POLYNOMIAL INTERPOLATION; NEWTON FORM; FEJER POINTS ID SPECTRAL METHODS; TIME AB Polynomial interpolation is an essential subject in numerical analysis. Dealing with a real interval, it is well known that even if f(x) is an analytic function, interpolating at equally spaced points can diverge [P. J. Davis, Interpolation and Approximation, Dover, New York, 1975]. On the other hand, interpolating at the zeros of the corresponding Chebyshev polynominal will converge. Using the Newton formula, this result of convergence is true only on the theoretical level. It is shown that the algorithm which computes the divided differences is numerically stable only if: (1) The interpolating points are arranged in a certain order. (2) The size of the interval is four. Stabilizing Newton interpolation is described in greater generality of interpolation in the complex plane. High degree polynomial interpolation is employed in approximation of functions of matrices. Some applications of the results described in the paper for this purpose are given. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. RP TALEZER, H (reprint author), TEL AVIV UNIV,SCH MATH SCI,IL-69978 TEL AVIV,ISRAEL. NR 18 TC 20 Z9 20 U1 1 U2 3 PU SIAM PUBLICATIONS PI PHILADELPHIA PA 3600 UNIV CITY SCIENCE CENTER PH#382-9800, PHILADELPHIA, PA 19104-2688 SN 0196-5204 J9 SIAM J SCI STAT COMP PD MAY PY 1991 VL 12 IS 3 BP 648 EP 667 DI 10.1137/0912034 PG 20 WC Mathematics, Applied SC Mathematics GA FH213 UT WOS:A1991FH21300009 ER PT J AU SHING, YH POOL, FS AF SHING, YH POOL, FS TI ELECTRON-CYCLOTRON RESONANCE MICROWAVE PLASMA DEPOSITION OF A-SI-H AND A-SIC-H FILMS SO SOLAR CELLS LA English DT Article; Proceedings Paper CT 10TH PHOTOVOLTAIC RESEARCH AND DEVELOPMENT PROJECT REVIEW MEETING CY OCT 23-25, 1990 CL LAKEWOOD, CO ID ECR PLASMA AB Amorphous silicon and silicon carbon alloy thin films (a-Si:H, a-SiC:H) were deposited by electron cyclotron resonance (ECR) microwave plasmas using SiH4, CH4 and hydrogen gas mixtures. The ECR-deposited, photosensitive a-Si:H films show a light conductivity of 5 X 10(-5) OMEGA-1 cm-1, and a light-to-dark conductivity ratio of about 2 x 10(6). Optical bandgaps of ECR-deposited a-Si:H films are in the range 1.75-1.85 eV. The integrated defect density in the mobility gap of the photosensitive a-Si:H film was determined by junction capacitance measurements to be 1.6 x 10(16) cm-3. A new type of conductive a-SiC:H film, which may contain a microcrystalline phase, was also deposited by ECR PECVD. The p-type doped ECR-deposited, conductive a-Si:H films show a conductivity of 5 X 10(-2) OMEGA-1 cm-1. The ECR-deposited a-SiC:H films show slightly higher optical bandgaps than those of r.f.-deposited a-SiC:H films. Hydrogen dilution in the ECR plasma with a dilution ratio up to 5 shows no significant effect on the optical bandgap of a-SiC:H films. The deposition rate of a-SiC:H films is found to be strongly dependent on the ECR magnetic field and the hydrogen dilution. The hydrogen dilution effect on the deposition rate indicates that the etching in ECR hydrogen plasmas plays an important role in the deposition of a-SiC:H films. The two-phase nature of ECR-deposited, microcrystalline silicon carbon films (mu-SiC:H) is shown by X-ray diffraction to consist of 1000 angstrom microcrystallites of alpha-SiC and amorphous network structures. RP SHING, YH (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 11 TC 6 Z9 6 U1 0 U2 0 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0379-6787 J9 SOL CELLS PD MAY PY 1991 VL 30 IS 1-4 BP 391 EP 401 DI 10.1016/0379-6787(91)90072-W PG 11 WC Energy & Fuels SC Energy & Fuels GA FQ725 UT WOS:A1991FQ72500042 ER PT J AU CHEN, JS KOLAWA, E NICOLET, MA RUIZ, RP AF CHEN, JS KOLAWA, E NICOLET, MA RUIZ, RP TI CU/IN DEPOSITED AT ROOM-TEMPERATURE - MORPHOLOGY, PHASES AND REACTIONS SO SOLAR CELLS LA English DT Article; Proceedings Paper CT 10TH PHOTOVOLTAIC RESEARCH AND DEVELOPMENT PROJECT REVIEW MEETING CY OCT 23-25, 1990 CL LAKEWOOD, CO AB Bilayers of a slightly copper-rich composition of copper and indium deposited (in that order) at room temperature by vacuum evaporation, electroplating, and r.f sputtering, were analyzed by MeV He-4 backscattering spectrometry, scanning electron microscopy and X-ray diffraction before and after thermal annealing at 400-degrees-C in vacuum. The surface morphology of as-deposited samples is roughest for evaporated samples and smoothest for samples deposited by sputtering with low r.f. power. All as-deposited samples contain copper and indium phases and the metastable Culn compound. After 1 h at 400-degrees-C, this metastable phase and that of copper disappear and are replaced by some copper-rich compound (Cu9In4, Cu7In4) in all cases. Simultaneously, the surface morphology smooths out considerably for the initially rough samples. Bilayers of various Cu/In compositions were also prepared. The results are consistent with the absence of stable compounds outside the 26-38 at.% indium range, as indicated by published phase diagrams. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP CHEN, JS (reprint author), CALTECH,PASADENA,CA 91125, USA. RI Chen, Jen-Sue/A-3298-2015 NR 8 TC 9 Z9 11 U1 1 U2 1 PU ELSEVIER SCIENCE SA LAUSANNE PI LAUSANNE 1 PA PO BOX 564, 1001 LAUSANNE 1, SWITZERLAND SN 0379-6787 J9 SOL CELLS PD MAY PY 1991 VL 30 IS 1-4 BP 451 EP 458 DI 10.1016/0379-6787(91)90077-3 PG 8 WC Energy & Fuels SC Energy & Fuels GA FQ725 UT WOS:A1991FQ72500047 ER PT J AU BARNES, RJH AF BARNES, RJH TI TREATIES ARE NOT THE ANSWER SO SPACE POLICY LA English DT Letter RP BARNES, RJH (reprint author), NASA,INT RELAT,WASHINGTON,DC 20007, USA. NR 0 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 0265-9646 J9 SPACE POLICY JI Space Policy PD MAY PY 1991 VL 7 IS 2 BP 167 EP 168 DI 10.1016/0265-9646(91)90031-C PG 2 WC International Relations; Social Sciences, Interdisciplinary SC International Relations; Social Sciences - Other Topics GA FQ482 UT WOS:A1991FQ48200014 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR AF BAUSCHLICHER, CW LANGHOFF, SR TI COMPUTATION OF ELECTRONIC-TRANSITION MOMENTS - THE LENGTH VERSUS THE VELOCITY REPRESENTATION SO THEORETICA CHIMICA ACTA LA English DT Article DE TRANSITION MOMENTS; CONVERGENCE; LENGTH REPRESENTATION; VELOCITY REPRESENTATION ID RADIATIVE LIFETIME; C-2 AB We have compared transition moments (TMs) obtained using the length and velocity representations for transitions from the ground state of H-2 to the lowest two 1-PI-u and two 1-SIGMA-u+ Rydberg states, the A1-PI-X1-SIGMA+ transition in BH, and the A1-PI-u-X1-SIGMA-g+ transition in C2. For H-2, the TMs in the length and velocity representations agree well even in cases where the one-particle basis is incomplete and the TM has not converged. For BH and C2 the TM in the length representation converges rapidly with improvements in the one-particle basis set and is insensitive to inner-shell correlation. In contrast, in the velocity representation convergence with improvements in the one-particle basis is much slower, especially for C2, and the TMs are significantly changed by inner-shell correlation. Thus the difference between the TMs in the length and velocity representations would not appear to be a viable diagnostic of TM convergence. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 14 TC 27 Z9 27 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0040-5744 J9 THEOR CHIM ACTA JI Theor. Chim. Acta PD MAY PY 1991 VL 79 IS 2 BP 93 EP 103 DI 10.1007/BF01127098 PG 11 WC Chemistry, Physical SC Chemistry GA FN375 UT WOS:A1991FN37500002 ER PT J AU OCONNOR, DB SCOTT, GW COULTER, DR YAVROUIAN, A AF OCONNOR, DB SCOTT, GW COULTER, DR YAVROUIAN, A TI EMISSION-SPECTRA AND KINETICS OF COPOLYMER FILMS OF STYRENE AND 2,3,4,5,6-PENTAFLUOROSTYRENE SO MACROMOLECULES LA English DT Article ID PHOTOCHEMICAL PROCESSES; POLYMERIC SYSTEMS; ENERGY-TRANSFER; POLYSTYRENE; MIGRATION AB The temperature-dependent steady-state emission spectra and fluorescence kinetics of copolymer films of styrene and 2,3,4,5,6-pentafluorostyrene are reported. The polystyrene excimer emission is efficiently quenched in the presence of relatively small amounts of the pentafluorophenyl quencher in spite of the fact that direct energy transfer from the excimer to the quencher chromophores is not possible. The quenching of the polystyrene excimer emission at room temperature and of the polystyrene monomer emission at 13 K is attributed to the interception of the migrating monomer excitation by the quencher. The data suggest that this quenching mechanism is independent of temperature. C1 UNIV CALIF RIVERSIDE,DEPT CHEM,RIVERSIDE,CA 92521. CALTECH,JET PROP LAB,SPACE MAT SCI & TECHNOL SECT,PASADENA,CA 91109. NR 29 TC 5 Z9 5 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0024-9297 J9 MACROMOLECULES JI Macromolecules PD APR 29 PY 1991 VL 24 IS 9 BP 2355 EP 2360 DI 10.1021/ma00009a036 PG 6 WC Polymer Science SC Polymer Science GA FJ881 UT WOS:A1991FJ88100036 ER PT J AU TEMKIN, A AF TEMKIN, A TI THRESHOLD LAW FOR ELECTRON ATOM IMPACT IONIZATION - TOWARDS THE INSIDE CONTRIBUTION OF THE COULOMB-DIPOLE THEORY SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID 2 ELECTRONS AB We have previously derived an ionization threshold law on the basis of the Coulomb-dipole theory, but including only the contribution from the outer (semi-asymptotic) region of configuration space to the relevant matrix element. We here initiate a study of the (overwhelmingly dominant) inside contribution. The main part of this paper is devoted to a detailed analysis of the asymptotic form to which the inside function must be attached. We return to an older approach of deriving the ionization yield by extrapolating excitation cross sections of excited states (N) (because the asymptotic form there is known to be dipole configurations of degenerate (l) states for each N excited by the incoming electron) into the continuum. Here we concentrate on the dipole matrix from which the dipole configurations are obtained; it is derived analytically; its eigenfunctions and eigenvalues are evaluated numerically to very high N (for several of the lower partial waves L). A key parameter emerges, J(C)(N, L), which specifies the number of coherent, attractive, dipole states as a function of N and L. As a first exercise this asymptotic form is matched to a two-Coulomb wavefunction in the interior; for this simplistic ansatz the analysis leads to a linear threshold law. The most important aspect of the paper is that the stage has been set for a rigorous study and calculation of the inside contribution as it affects the threshold law. RP TEMKIN, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 19 TC 5 Z9 5 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD APR 28 PY 1991 VL 24 IS 8 BP 2147 EP 2159 DI 10.1088/0953-4075/24/8/025 PG 13 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA FK731 UT WOS:A1991FK73100025 ER PT J AU ORTON, GS FRIEDSON, AJ CALDWELL, J HAMMEL, HB BAINES, KH BERGSTRALH, JT MARTIN, TZ MALCOM, ME WEST, RA GOLISCH, WF GRIEP, DM KAMINSKI, CD TOKUNAGA, AT BARON, R SHURE, M AF ORTON, GS FRIEDSON, AJ CALDWELL, J HAMMEL, HB BAINES, KH BERGSTRALH, JT MARTIN, TZ MALCOM, ME WEST, RA GOLISCH, WF GRIEP, DM KAMINSKI, CD TOKUNAGA, AT BARON, R SHURE, M TI THERMAL MAPS OF JUPITER - SPATIAL-ORGANIZATION AND TIME-DEPENDENCE OF STRATOSPHERIC TEMPERATURES, 1980 TO 1990 SO SCIENCE LA English DT Article ID ATMOSPHERE; VOYAGER-1 AB The spatial organization and time dependence of Jupiter's stratospheric temperatures have been measured by observing thermal emission from the 7.8-micrometer CH4 band. These temperatures, observed through the greater part of a Jovian year, exhibit the influence of seasonal radiative forcing. Distinct bands of high temperature are located at the poles and mid-latitudes, while the equator alternates between warm and cold with a period of approximately 4 years. Substantial longitudinal variability is often observed within the warm mid-latitude bands, and occasionally elsewhere on the planet. This variability includes small, localized structures, as well as large-scale waves with wavelengths longer than approximately 30,000 kilometers. The amplitudes of the waves vary on a time scale of approximately 1 month; structures on a smaller scale may have lifetimes of only days. Waves observed in 1985, 1987, and 1988 propagated with group velocities less than +/- 30 meters per second. C1 YORK UNIV,DEPT PHYS,N YORK M3J 1P3,ONTARIO,CANADA. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. NASA,WASHINGTON,DC 20546. TRW CO INC,REDONDO BEACH,CA 90278. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. RP ORTON, GS (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 60 Z9 60 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 26 PY 1991 VL 252 IS 5005 BP 537 EP 542 DI 10.1126/science.252.5005.537 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FJ127 UT WOS:A1991FJ12700038 PM 17838486 ER PT J AU ROTH, LM FREISER, BS BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR AF ROTH, LM FREISER, BS BAUSCHLICHER, CW PARTRIDGE, H LANGHOFF, SR TI HETERONUCLEAR DIATOMIC METAL CLUSTER IONS IN THE GAS-PHASE - THEORETICAL TREATMENT OF MGFE+ AND STUDY OF ITS REACTIONS WITH HYDROCARBONS SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID TRANSFORM MASS-SPECTROMETRY; COLLISION-INDUCED DISSOCIATION; GTO BASIS-SETS; BINDING-ENERGIES; 2ND-ROW ATOMS; ALKANES; CHEMISTRY; FE+; PHOTODISSOCIATION; REACTIVITY AB The unique reactivity of MgFe+ is described. This cluster reacts with linear alkenes (C2-C6) by displacement of magnesium to form an Fe+-olefin product. In contrast, MgFe+ reacts with alcohols by displacement of the iron to form a Mg+-alcohol product. This is the first example of a changeover in the relative metal-ligand bond energies with both metals in a dimer being selectively displaced. MgFe+ also reacts with cyclic alkenes. For example, it dehydrogenates cyclohexene to form MgFe+-benzene, which reacts further to displace the magnesium and form benzene-Fe+-cyclohexene. MgFe+ is unreactive with small alkanes (C2-C4) but reacts with larger alkanes (C5-C7) to form a MgFe+-alkene product. An upper limit of 34 +/- 5 kcal/mol for D-degrees(Mg+-Fe) has been established by use of iron-molecule reactions. In contrast, the photodissociation threshold for MgFe+ to form Fe+ yields an upper limit of D-degrees(Mg+-Fe) less-than-or-equal-to 44 +/- 3 kcal/mol. Theoretical calculations show that MgFe+ has a X6-DELTA ground state and bonds by forming a covalent Fe(4s)-Mg(3s) bond. The computed binding energy of 29.4 kcal/mol, which is expected to be a lower bound, is consistent with the upper limit determined from ion-molecule reactions. The calculations show that the photon absorption at congruent-to 49 kcal/mol corresponds to the intense (2)6-DELTA <-- X6-DELTA transition. This explains the large difference between the dissociation energy deduced from the ion-molecule reactions and the upper bound determined from photodissociation. C1 PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 51 TC 16 Z9 16 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD APR 24 PY 1991 VL 113 IS 9 BP 3274 EP 3280 DI 10.1021/ja00009a009 PG 7 WC Chemistry, Multidisciplinary SC Chemistry GA FJ121 UT WOS:A1991FJ12100009 ER PT J AU RINSLAND, CP GOLDMAN, A SMITH, MAH DEVI, VM AF RINSLAND, CP GOLDMAN, A SMITH, MAH DEVI, VM TI MEASUREMENTS OF LORENTZ AIR-BROADENING COEFFICIENTS AND RELATIVE INTENSITIES IN THE H2O16 PURE ROTATIONAL AND NU-2 BANDS FROM LONG HORIZONTAL PATH ATMOSPHERIC SPECTRA SO APPLIED OPTICS LA English DT Article ID DIODE-LASER MEASUREMENTS; ASYMMETRIC-TOP MOLECULES; 720-NM WAVELENGTH REGION; WATER-VAPOR; VIBRATION LINES; N-2-BROADENED HALFWIDTHS; TEMPERATURE-DEPENDENCE; PERTURBER DEPENDENCES; INFRARED-SPECTRUM; SOLAR SPECTRA AB Lorentz air-broadening coefficients and relative intensities have been measured for forty-three lines in the pure rotational band and twenty lines in the nu-2 band of H2 O-16 between 800 and 1150 cm-1. The results were derived from analysis of nine 0.017-cm-1 resolution atmospheric absorption spectra recorded over horizontal paths of 0.5-1.5 km with the McMath Fourier transform spectrometer and main solar telescope operated on Kitt Peak by the National Solar Observatory. A nonlinear least-squares spectral fitting technique was used in the spectral analysis. The results are compared with previous measurements and calculations. In most cases, the measured pressure-broadening coefficients and intensities are significantly different from the values in the 1986 HITRAN line parameters compilation. C1 COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,CHEM & DYNAM BRANCH,HAMPTON,VA 23665. RP RINSLAND, CP (reprint author), UNIV DENVER,DEPT PHYS,DENVER,CO 80208, USA. NR 45 TC 37 Z9 37 U1 1 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD APR 20 PY 1991 VL 30 IS 12 BP 1427 EP 1438 PG 12 WC Optics SC Optics GA FJ906 UT WOS:A1991FJ90600001 PM 20700300 ER PT J AU BROWELL, EV ISMAIL, S GROSSMANN, BE AF BROWELL, EV ISMAIL, S GROSSMANN, BE TI TEMPERATURE SENSITIVITY OF DIFFERENTIAL ABSORPTION LIDAR MEASUREMENTS OF WATER-VAPOR IN THE 720-NM REGION SO APPLIED OPTICS LA English DT Article ID WAVELENGTH REGION AB Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evaluate the temperature sensitivity of differential absorption lidar (DIAL) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E", the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for sixty-seven H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E" values in the 100-300-cm-1 range were found to be optimum for DIAL measurements of H2O number densities, while E" values in the 250-500-cm-1 range were found to be optimum for H2O mixing ratio measurements. RP BROWELL, EV (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 15 TC 27 Z9 27 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD APR 20 PY 1991 VL 30 IS 12 BP 1517 EP 1524 PG 8 WC Optics SC Optics GA FJ906 UT WOS:A1991FJ90600015 PM 20700314 ER PT J AU OTTERMAN, J BRAKKE, TW AF OTTERMAN, J BRAKKE, TW TI MULTIPLE VS SINGLE SCATTERING - ASSESSMENT OF MAGNITUDES SO APPLIED OPTICS LA English DT Article DE CANOPY REFLECTANCE; MULTIPLE SCATTERING ID CANOPY; MODEL; PLANE; SOIL AB All orders of scattering are analyzed for two artificial canopies. The SHL canopy consists of Small Horizontal Leaves that are much smaller than the leaf-to-leaf spacing. The IHL canopy consists of Infinite Horizontal Layers, where each leaf is of infinite extent (a horizontal plane). Hemispheric leaf reflectances and transmittances independent of the direction of illumination lead to exact solutions for these models. Sunlight that penetrates to a given leaf area index level is much stronger in an SHL canopy than that in IHL; but the difference becomes muted when leaf transmittance is large. Multiple scattering enhances the hemispheric canopy reflectance more strongly in SHL than it does in IHL. The enhancement depends linearly on leaf transmittance in SHL and on the transmittance squared in IHL. Comparison with measured reflectances indicates that IHL model grossly underestimates multiple scattering in soybean canopies. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP OTTERMAN, J (reprint author), TEL AVIV UNIV,DEPT GEOPHYS,IL-69978 TEL AVIV,ISRAEL. NR 12 TC 3 Z9 3 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD APR 20 PY 1991 VL 30 IS 12 BP 1562 EP 1566 PG 5 WC Optics SC Optics GA FJ906 UT WOS:A1991FJ90600020 PM 20700319 ER PT J AU KROLIK, JH HORNE, K KALLMAN, TR MALKAN, MA EDELSON, RA KRISS, GA AF KROLIK, JH HORNE, K KALLMAN, TR MALKAN, MA EDELSON, RA KRISS, GA TI ULTRAVIOLET VARIABILITY OF NGC-5548 - DYNAMICS OF THE CONTINUUM PRODUCTION REGION AND GEOMETRY OF THE BROAD-LINE REGION SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC 5548); GALAXIES, NUCLEI; GALAXIES, SEYFERT; LINE PROFILES; RADIATION MECHANISMS; ULTRAVIOLET, SPECTRA ID ACTIVE GALACTIC NUCLEI; TIME-SERIES ANALYSIS; SEYFERT-GALAXIES; ACCRETION DISKS; EMISSION-LINES; QUASARS; MODELS; SPECTRUM; OPACITY AB We have used the data obtained in the 1989-1990 IUE monitoring of NGC 5548 to derive a mean shape for the ionizing spectrum; mean line profiles; the continuum fluctuation power spectrum in three UV bands; cross-correlation functions relating these bands; cross-correlation functions relating fluctuations in eight emission lines to fluctuations in the UV continuum; and the response functions through which the continuum fluctuations appear to generate the fluctuations in each of these eight lines. The mean shape of the UV continuum is well fit by an accretion disk model with a black hole mass of 1 x 10(8)h-1/sin i M.; however, an additional component is required to reproduce the observed soft X-ray flux. Construction of mean line profiles gives both a separation of the broad and narrow components in the lines and also a measurement of the velocity widths for the broad components. The widths of the lines increase with increasing ionization stage. We find that the continuum fluctuation power spectrum is very steep, with most of the variance coming from approximately 1 yr time scales. The entire optical/UV continuum rises and falls almost simultaneously, so that the logarithmic slope of the power spectrum (between -2 and -3) is nearly the same for all bands, but the flux at higher photon frequencies varies with larger amplitude. Within the context of thermal accretion disk models for the production of the UV continuum, these results lead to two important inferences: that orbital dynamics at the place where the radiation is generated do not control the dominant fluctuations; and the radial group speed of accretion disk temperature fluctuations is greater than c/10. A possible explanation for the near-simultaneity of fluctuations in the UV and optical bands is that much of the optical continuum is due to reprocessing by outer, cooler material of UV photons created closer in. The emission-line response functions map the marginal emission-line emissivity onto a set of paraboloidal isodelay surfaces. Combining the response functions with photoionization models, we find that the emission-line material around this Seyfert nucleus may best be described by a highly ionized inner zone of high and nearly constant pressure (nT approximately 10(15) K cm-3) that stretches from congruent-to 4 - 14 lt-days from the center, and an outer, more weakly ionized zone of considerably lower ionization at least congruent-to 20-30 lt-days out. Both zones are suggested by photoionization models of the mean line ratios. While the inner region is probably roughly spherical, there are indications that the outer region is flattened. It is possible that the low-ionization region forms a ringlike structure of radius approximately 100 lt-day which is roughly edge-on to the line of sight. Most of the mass in the emission-line region is in the low-ionization portion, but the bulk of the line luminosity (excluding Fe II) comes from the high-ionization part. The dispersion in line-of-sight velocity for each line is well correlated with the lag at which the cross-correlation function with respect to the Uv continuum peaks: sigma-proportional-tau-l-0.51. Such a correlation is consistent with the view that gravity is responsible for the motions of the line-emitting material if the central mass is approximately 10(7)-10(8) M.; this mass range is (barely) consistent with the mass estimated on the basis of the accretion disk spectral fit. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. UNIV COLORADO,CTR ASTROPHYS & SPACE ASTRON,BOULDER,CO 80309. RP KROLIK, JH (reprint author), JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218, USA. NR 44 TC 261 Z9 262 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1991 VL 371 IS 2 BP 541 EP 562 DI 10.1086/169918 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF983 UT WOS:A1991FF98300010 ER PT J AU CLARK, FO LAUREIJS, RJ PRUSTI, T AF CLARK, FO LAUREIJS, RJ PRUSTI, T TI THE TEMPERATURE OF LARGE DUST GRAINS IN MOLECULAR CLOUDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR, GRAINS; INTERSTELLAR, MOLECULES ID INFRARED-EMISSION; THERMAL EMISSION; GAS EMISSION; IRAS; GLOBULES; HYDROGEN; DENSITY; TAURUS AB The temperature of the large dust grains is calculated from three molecular clouds ranging in visual extinction from 2.5 to 8 mag, by comparing maps of either extinction derived from star counts or gas column density derived from molecular observations to I100. Both techniques show the dust temperature declining into clouds. The two techniques do not agree in absolute scale. C1 CALTECH, JET PROP LAB, CTR INFRARED PROC & ANAL, PASADENA, CA 91109 USA. LAB SPACE RES, 9700 AV GRONINGEN, NETHERLANDS. RP CLARK, FO (reprint author), USAF, GL, OPC, BEDFORD, MA 01731 USA. NR 30 TC 9 Z9 9 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1991 VL 371 IS 2 BP 602 EP 606 DI 10.1086/169924 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF983 UT WOS:A1991FF98300016 ER PT J AU SANDFORD, SA ALLAMANDOLA, LJ TIELENS, AGGM SELLGREN, K TAPIA, M PENDLETON, Y AF SANDFORD, SA ALLAMANDOLA, LJ TIELENS, AGGM SELLGREN, K TAPIA, M PENDLETON, Y TI THE INTERSTELLAR C-H STRETCHING BAND NEAR 3.4 MICRONS - CONSTRAINTS ON THE COMPOSITION OF ORGANIC MATERIAL IN THE DIFFUSE INTERSTELLAR-MEDIUM SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SPECTRA; INTERSTELLAR, GRAINS; INTERSTELLAR, MOLECULES ID WOLF-RAYET STARS; GALACTIC-CENTER; MU-M; INFRARED OBSERVATIONS; ABSORPTION-BANDS; SPECTROSCOPY; EXTINCTION; DUST; PHOTOMETRY; SPECTRA AB To better constrain and quantify the composition of material in the diffuse interstellar medium (ISM), absorption spectra between 3600 and 2700 cm-1 (2.8 and 3.7-mu-m) have been taken of objects which have widely varying amounts of visual extinction along different lines of sight. The spectra of these objects contain a broad feature centered at approximately 3300 cm-1 (approximately 3.0-mu-m), attributed to O-H stretching vibrations, and/or a feature near 2950 cm-1 (3.4-mu-m) attributed to C-H stretching vibrations. The lack of correlation between the strengths of these two bands indicates that they do not arise from the same molecular carrier. The features in the 3100-2700 cm-1 (3.2-3.7-mu-m) region fall into one of two classes. We attribute the first class of features to material in the diffuse ISM on the basis of the similarity between the band profiles along the very different lines of sight to Galactic center source IRS 7 and VI Cygni #12. Similar features are also reported for Galactic center source IRS 3, Ve 2-45, and AFGL 2179. Higher resolution spectra of the objects OH 01-477 and T629-5, which are known to be M stars, are dominated by a series of narrow bands in this region. These bands are largely due to OH in the stars' photospheres. While the spectra of OH 01-477 and T629-5 are likely to contain C-H absorption from diffuse ISM dust, the strength of the overlapping photospheric OH features presently prevents us from quantifying the depths of the interstellar C-H feature towards these objects. The interstellar feature for Galactic center source IRS 7 has subpeaks near 2955, 2925, and 2870 cm-1 (+/- 5 cm-1), which we attribute to C-H stretching vibrations in the -CH2- and -CH3 groups of aliphatic hydrocarbons. These band positions fall within 5 cm-1 of the values normal for saturated aliphatics. The absence of a distinct band near 2855 cm-1 suggests that the material contains small amounts of electronegative groups like -O-H or -C=N. The relative strengths and profiles of the 2955 and 2925 cm-1 features towards five objects suggests an average diffuse ISM line-of-sight -CH2-/-CH3 ratio of about 2.5, indicating the presence of relatively complex organic materials. The strengths of the subpeaks at 2925 and 2955 cm-1, due to -CH2- and -CH3 groups, respectively, correlate with visual extinction, strongly suggesting that the C-H stretching band is a general feature of the material along different lines of sight in the diffuse ISM. We find average ratios of A-upsilon/tau(2925 cm-1) = 240 +/- 40 and A-upsilon/tau(2955 cm-1) = 310 +/- 90 for the objects we have observed. We deduce that 2.6%-35% of the cosmic carbon in the ISM is tied up in the carrier of this band with the most likely value falling near 10%. The interstellar C-H band is remarkably similar to the feature in lab residues produced by irradiating analogs of dense molecular cloud ices. This is consistent with a model in which the hydrocarbon component in the diffuse interstellar medium consists of complex hydrocarbons containing aliphatic side chains and bridges which are produced in dense molecular clouds and subsequently modified in the diffuse medium. C1 UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. RP SANDFORD, SA (reprint author), NASA,AMES RES CTR,MAIL STOP 245-6,MOFFETT FIELD,CA 94035, USA. NR 68 TC 233 Z9 235 U1 0 U2 7 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1991 VL 371 IS 2 BP 607 EP 620 DI 10.1086/169925 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF983 UT WOS:A1991FF98300017 PM 11538103 ER PT J AU BROWN, LE DEARBORN, DS SCHRAMM, DN LARSEN, JT KUROKAWA, S AF BROWN, LE DEARBORN, DS SCHRAMM, DN LARSEN, JT KUROKAWA, S TI THE SHOCK PROCESS AND LIGHT-ELEMENT PRODUCTION IN SUPERNOVA ENVELOPES SO ASTROPHYSICAL JOURNAL LA English DT Article DE NUCLEOSYNTHESIS; SHOCK WAVES; STARS, INTERIORS; STARS, SUPERNOVAE ID LITHIUM; STARS; NUCLEOSYNTHESIS; RATES; ORIGIN; LI AB Detailed hydrodynamic modeling of the passage of supernova shocks through the hydrogen envelopes of blue and red progenitor stars has been carried out to explore the sensitivity to model conditions of light-element production (specifically Li-7 and B-11) which was noted by Dearborn and coworkers. It is found that, for stellar models with M less-than-or-similar-to 100 M., current state-of-the-art supernova shocks do not produce significant light-element yields by hydrodynamic processes alone. The dependence of this conclusion on stellar models and on shock strengths is explored. Preliminary implications for Galactic evolution of lithium are discussed, and it is suspected that intermediate-mass red giant stars may be the most consistent production site for lithium. C1 UNIV CHICAGO,DEPT PHYS & ASTRON,CHICAGO,IL 60637. FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CALIF LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. CASCADE APPL SCI,BOULDER,CO 80306. NR 36 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1991 VL 371 IS 2 BP 648 EP 664 DI 10.1086/169931 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF983 UT WOS:A1991FF98300023 ER PT J AU BLONDIN, JM STEVENS, IR KALLMAN, TR AF BLONDIN, JM STEVENS, IR KALLMAN, TR TI ENHANCED WINDS AND TIDAL STREAMS IN MASSIVE X-RAY BINARIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDRODYNAMICS; STARS, WINDS; X-RAYS, BINARIES ID RADIATION-DRIVEN WINDS; VELA X-1; NUMERICAL SIMULATIONS; ACCRETION FLOW; STELLAR WINDS; STARS; SPECTRUM AB The tidal effects created by the presence of a compact companion are expected to induce a stream of enhanced wind from the early-type primary star in massive X-ray binary systems. In this paper we present two-dimensional gas-dynamical simulations of such streams. We find that the wind enhancement is a sensitive function of the binary separation, and develops into a tidal stream as the primary approaches its critical surface. For typical system parameters, the Coriolis force deflects the stream sufficiently that it does not impact directly on the compact companion but passes behind it. The density in the stream can reach values of 20-30 times the ambient wind density, leading to strong attenuation of the X-ray flux that passes through the tidal stream, providing a possible explanation of the enhanced absorption events seen at later phases in the X-ray observations of massive X-ray binary systems such as Vela X-1. In contrast to the time-variable accretion wake, the tidal stream is relatively stationary, producing absorption features that should remain fixed from orbit to orbit. For systems with a strong tidal stream, the large asymmetry in the accreting wind results in the accretion of angular momentum of constant sign, as opposed to systems without streams, where the sign of the accreted angular momentum can change. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP BLONDIN, JM (reprint author), UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903, USA. NR 39 TC 78 Z9 78 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1991 VL 371 IS 2 BP 684 EP 695 DI 10.1086/169934 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF983 UT WOS:A1991FF98300026 ER PT J AU MICHALITSIANOS, AG MARAN, SP OLIVERSEN, RJ BOPP, B KONTIZAS, E DAPERGOLAS, A KONTIZAS, M AF MICHALITSIANOS, AG MARAN, SP OLIVERSEN, RJ BOPP, B KONTIZAS, E DAPERGOLAS, A KONTIZAS, M TI OBSERVATIONS OF THE PECULIAR OBJECT MWC-560 IN OUTBURST SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, INDIVIDUAL (MWC-560); STARS, SYMBIOTIC; STARS, WINDS; ULTRAVIOLET, SPECTRA AB The ultraviolet spectrum of the peculiar emission-line star MWC 560 varied markedly on time scales of weeks while a photometric outburst was in progress, as shown by the International Ultraviolet Explorer (IUE) observations obtained on five occasions during the period 1990 February 3 to 1990 April 30. In addition, significant changes in ultraviolet flux and in the equivalent widths of strong absorption features were detected in spectra taken less than 3 hr apart on 1990 April 29 and 30. The ultraviolet spectra are consistent with the ejection of an optically thick shell that produced strong absorption blends of Fe II and Cr II. Using IUE spectra previously obtained of MWC 560 on 1984 March 10 as a wavelength template, our observations that cover nearly 3 months starting on 1990 February 3 indicate a significant shift toward shorter wavelengths, which corresponds to velocities that range between approximately -500 and -5300 km s-1. Although MWC 560 has been considered as a symbiotic system, the velocities reported here exceed by far those previously found in symbiotic stars or recurrent novae. A broad, P Cygni-type absorption profile observed in the Mg II h and k lines extends to velocities in excess of 6000 km s-1 shortward of the corresponding emission peaks. These velocities exceed those seen in cataclysmic variables or recurrent novae during outbursts, but the ultraviolet spectra of MWC 560 do not resemble the UV spectra of these types of systems. The profile of the Mg II P Cygni feature varied significantly. In addition to the variable, high-velocity system of broad absorption features, a relatively stable system of Mg II, Mg I, Fe II, Cr II, and other ionic absorptions, at velocities of approximately +40 to +50 km s-1 with respect to rest was observed. Emission lines arising from the same multiplets as this low-velocity system were detected in the P Cygni trough of the Mg II h and k. The +40 to +50 km s-1 absorption and emission lines are attributed to a circumstellar shell that presumably was formed by earlier mass loss. The ultraviolet spectra presented here are supported by ground-based photoelectric photometry and high-dispersion H-alpha spectroscopy. The spectroscopic phenomena in MWC 560 resemble those found in XX Ophiuchi, "Merrill's Iron Star," more closely than those in any other system known to us, but the velocities in MWC 560 are an order of magnitude higher than those found in XX Oph. The MWC 560 phenomenon may represent a previously unobserved phase in the evolution of symbiotic binary systems or else a related type of system that may not have been previously recognized. C1 UNIV TOLEDO,DEPT PHYS & ASTRON,RITTER ASTROPHYS RES CTR,TOLEDO,OH 43606. NATL OBSERV,INST ASTRON,GR-11810 ATHENS,GREECE. UNIV ATHENS,DEPT PHYS & THEORECT MECH,MECH SECT,GR-15783 ATHENS,GREECE. UNIV ATHENS,ASTROPHYS SECT,GR-15783 ATHENS,GREECE. UNIV ATHENS,ASTRON SECT,GR-15783 ATHENS,GREECE. RP MICHALITSIANOS, AG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6841,GREENBELT,MD 20771, USA. RI Dapergolas, Anastasios/L-4954-2013; Kontizas, Evangelos/A-1969-2014 NR 30 TC 24 Z9 24 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1991 VL 371 IS 2 BP 761 EP 771 DI 10.1086/169940 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF983 UT WOS:A1991FF98300032 ER PT J AU CHITRE, SM DAVILA, JM AF CHITRE, SM DAVILA, JM TI THE RESONANT ABSORPTION OF P-MODES BY SUNSPOTS WITH TWISTED MAGNETIC-FIELDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDROMAGNETICS; SUN, MAGNETIC FIELDS; SUN, OSCILLATIONS; SUN, SUNSPOTS ID CORONAL LOOPS; WAVES AB The observed absorption of solar p-mode flux by sunspots could provide a valuable diagnostic tool for probing the subsurface structure and evolution of the magnetic field of solar active regions once the physics of the process is understood. In this paper we consider a simplified inhomogeneous sunspot model with an axial current (twisted magnetic field). The absorption of incoming acoustic modes in a narrow resonance layer inside the sunspot flux tube is investigated, and the energy loss is estimated. For nonaxisymmetric modes the results are consistent with previous calculations. However, contrary to previous work, it is demonstrated that the existence of an azimuthal component of the magnetic field can lead to significant absorption of even the axisymmetric modes. If the absorption rate calculated in this paper is used in conjunction with the observed wavelength dependence of the absorption coefficient, it is found that the sunspot flux tube must have significant twist in the subsurface layers (B0-theta/B0z approximately 0.56). Furthermore, the presence of twist in the magnetic field leads to a natural explanation for the observed dependence on m, the azimuthal wave mode number, and the magnitude of the absorption coefficient can be accounted for in a self-consistent way. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP CHITRE, SM (reprint author), TATA INST FUNDAMENTAL RES,THEORET ASTROPHYS GRP,HOMI BHABHA RD,BOMBAY 400005,INDIA. NR 17 TC 8 Z9 8 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1991 VL 371 IS 2 BP 785 EP 792 DI 10.1086/169943 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF983 UT WOS:A1991FF98300035 ER PT J AU MURPHY, RJ RAMATY, R KOZLOVSKY, B REAMES, DV AF MURPHY, RJ RAMATY, R KOZLOVSKY, B REAMES, DV TI SOLAR ABUNDANCES FROM GAMMA-RAY SPECTROSCOPY - COMPARISONS WITH ENERGETIC PARTICLE, PHOTOSPHERIC, AND CORONAL ABUNDANCES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS, GENERAL; SUN, ABUNDANCES; SUN, FLARES; SUN, PARTICLE EMISSION ID FLARES AB We have derived accelerated particle and ambient gas abundances using solar flare gamma-ray spectroscopy. We compare the results with photospheric and coronal abundances, as well as with solar energetic particle abundances. This is the first time that the composition of accelerated particles interacting in an astrophysical source has been compared with the composition of particles escaping from the source. Our analysis shows that the derived composition of the accelerated particles is different from the composition of particles observed in large proton flares; rather, it resembles the composition observed in He-3-rich flares. Our analysis also suggests an ambient gas composition which differs from the composition of both the photosphere and the corona. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. TEL AVIV UNIV,RAYMOND & BEVERLY SACKLER FAC EXACT SCI,SCH PHYS & ASTRON,IL-69978 TEL AVIV,ISRAEL. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. NR 28 TC 146 Z9 148 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 20 PY 1991 VL 371 IS 2 BP 793 EP 803 DI 10.1086/169944 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF983 UT WOS:A1991FF98300036 ER PT J AU RIND, D CHANDLER, M AF RIND, D CHANDLER, M TI INCREASED OCEAN HEAT TRANSPORTS AND WARMER CLIMATE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID NORTH-ATLANTIC; SEA-ICE; SURFACE-TEMPERATURE; ATMOSPHERIC MODEL; CIRCULATION; WATER; LATITUDE; SALINITY; CYCLES; GROWTH AB We investigated the effect of increased ocean heat transports on climate in the Goddard Institute for Space Studies (GISS) general circulation model (GCM). The increases used were sufficient to melt all sea ice at high latitudes, and amounted to 15% on the global average. The resulting global climate is 2-degrees-C warmer, with temperature increases of some 20-degrees-C at high latitudes, and 1-degrees-C near the equator. The warming is driven by the decreased sea ice/planetary albedo, a feedback which would appear to be instrumental for producing extreme high-latitude amplification of temperature changes. Resulting hydrologic and wind stress changes suggest that qualitatively, for both the wind-driven and thermohaline circulation, the increased transports might be self-sustaining. As such, they would represent a possible mechanism to help account for the high-latitude warmth of climates in the Mesozoic and Tertiary, and decadal-scale climate fluctuations during the Holocene, as well as a powerful feedback to amplify other climate forcings. It is estimated that ocean transport increases of 50-70% would have been necessary to reproduce the warmth of various Mesozoic (65-230 m.y. ago) climates without changes in atmospheric composition, while the 15% increase used in these experiments would have been sufficient to reproduce the general climatic conditions of the Eocene (40-55 Ma). A companion experiment indicates that increased topography during the Cenozoic (0-65 Ma) might have altered the surface wind stress in a manner that led to reduced heat transports; this effect would then need to be considered in understanding the beginning of ice ages. Colder climates, or rapid climate perturbations, might have been generated with the aid of such altered ocean transports. The large high-latitude amplification associated with ocean heat transport and sea ice changes differs significantly from that forecast for increased trace gases, for which water vapor increase is the primary feedback mechanism. The different signatures might allow for discrimination of these different forcings; e.g., the warming of the 1930s looks more like the altered ocean heat transport signal, while the warming of the 1980s is more like the trace gas effect. The actual change of ocean heat transport and deepwater circulation both in the past and in the future represents a great uncertainty. C1 COLUMBIA UNIV, LAMONT DOHERTY GEOL OBSERV, PALISADES, NY 10964 USA. RP RIND, D (reprint author), NASA, GODDARD SPACE FLIGHT CTR, INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. NR 92 TC 133 Z9 134 U1 2 U2 17 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 20 PY 1991 VL 96 IS D4 BP 7437 EP 7461 DI 10.1029/91JD00009 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FJ455 UT WOS:A1991FJ45500012 ER PT J AU JOUZEL, J KOSTER, RD SUOZZO, RJ RUSSELL, GL WHITE, JWC BROECKER, WS AF JOUZEL, J KOSTER, RD SUOZZO, RJ RUSSELL, GL WHITE, JWC BROECKER, WS TI SIMULATIONS OF THE HDO AND (H2O)-O-18 ATMOSPHERIC CYCLES USING THE NASA GISS GENERAL-CIRCULATION MODEL - SENSITIVITY EXPERIMENTS FOR PRESENT-DAY CONDITIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CLIMATIC IMPLICATIONS; ANTARCTIC ICE; ISOTOPE; RECORD; WATER; CORE AB Incorporating the full geochemical cycles of stable water isotopes (HDO and H2O-18) into an atmospheric general circulation model (GCM) allows an improved understanding of global delta-D and delta-O-18 distributions and might even allow an analysis of the GCM's hydrological cycle. A detailed sensitivity analysis using the NASA/Goddard Institute for Space Studies (GISS) Model II GCM is presented that examines the nature of isotope modeling. The tests indicate that delta-D and delta-O-18 values in nonpolar regions are not strongly sensitive to details in the model precipitation parameterizations. This result, while implying that isotope modeling has limited potential use in the calibration of GCM convection schemes, also suggests that certain necessarily arbitrary aspects of these schemes are adequate for many isotope studies. Deuterium excess, a second-order variable, does show some sensitivity to precipitation parameterization and thus may be more useful for GCM calibration. Due to strong sensitivity over polar regions, GCM isotope modelers must choose carefully the numerical scheme for isotope transport and the formulation of kinetic fractionation processes at snow formation. The GCM results support the assumption that isotope fractionation does not occur during evaporation over continental areas. C1 COLUMBIA UNIV, LAMONT DOHERTY GEOL OBSERV, PALISADES, NY 10964 USA. NASA, GODDARD SPACE FLIGHT CTR, HYDROL SCI BRANCH, GREENBELT, MD 20771 USA. NASA, GODDARD SPACE FLIGHT CTR, INST SPACE STUDIES, NEW YORK, NY 10025 USA. UNIV COLORADO, INST ARCTIC & ALPINE RES, BOULDER, CO 80309 USA. RP JOUZEL, J (reprint author), CEA, DIV SCI MAT, DPHG, GEOCHIM ISOTOP LAB, F-91191 GIF SUR YVETTE, FRANCE. RI Koster, Randal/F-5881-2012; White, James/A-7845-2009 OI Koster, Randal/0000-0001-6418-6383; White, James/0000-0001-6041-4684 NR 36 TC 59 Z9 63 U1 1 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 20 PY 1991 VL 96 IS D4 BP 7495 EP 7507 DI 10.1029/90JD02663 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FJ455 UT WOS:A1991FJ45500015 ER PT J AU BARNES, RA MCMASTER, LR CHU, WP MCCORMICK, MP GELMAN, ME AF BARNES, RA MCMASTER, LR CHU, WP MCCORMICK, MP GELMAN, ME TI STRATOSPHERIC AEROSOL AND GAS EXPERIMENT-II AND ROCOZ-A OZONE PROFILES AT NATAL, BRAZIL - A BASIS FOR COMPARISON WITH OTHER SATELLITE INSTRUMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DATA ASSIMILATION SYSTEM; METEOROLOGICAL ROCKETSONDE; SPECTROMETER; INVERSION; SAGE; CONSTITUENTS; MESOSPHERE; PRECISION; ALGORITHM AB We present the results of comparisons of satellite measurements of ozone from the Stratospheric Aerosol and Gas Experiment II (SAGE II) with in situ measurements from ROCOZ-A and electrochemical concentration cell (ECC) ozonesondes at Natal, Brazil (5.9-degrees-S, 35.2-degrees-W), during the southern hemisphere autumn of 1985. Since data were collected over a region of low ozone variability, comparisons were made of the mean values of 14 SAGE II profiles with the mean values of 7 ROCOZ-A and 7 ECC profiles, rather than of a more limited set of paired comparisons. The basic comparison presented here is ozone number density versus geometric altitude, the fundamental ozone measurement from SAGE II. Over the altitude region from 20 to 52 km SAGE II ozone densities averaged 0.4% lower than ROCOZ-A. The average of the absolute values of the ozone density differences for the two instruments was 2.4% over these altitudes. Owing in large part to the number of profiles in the data sets, the 95% confidence limits for the ozone density differences in these comparisons averaged 3.5% from 20 to 52 km, a significant improvement over previous results. In terms of ozone mixing ratio versus geometric altitude from 20 to 52 km, SAGE II values had a difference of 3.4% from ROCOZ-A (SAGE II higher), an average absolute difference of 3.8%, and an average of 4.7% for the 95% confidence limits. Differences between the ozone density and mixing ratio results are due to the auxiliary temperature and pressure values for the satellite and in situ instruments. The effects of pressure differences on the vertical positioning of the ozone profiles are not important for the altitude-based comparisons of SAGE II and ROCOZ-A. However, they become an important consideration in the comparisons of SAGE II with pressure-based ozone measurements from other satellite instruments. The composite sets of ozone, temperature, and pressure values presented here form an excellent basis for comparisons with other satellite ozone measurements. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NOAA, NATL WEATHER SERV, NATL METEOROL CTR, CTR CLIMATE ANAL, WASHINGTON, DC 20233 USA. RP BARNES, RA (reprint author), CHEMAL INC, POB 44, WALLOPS ISL, VA 23337 USA. NR 61 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 20 PY 1991 VL 96 IS D4 BP 7515 EP 7530 DI 10.1029/90JD02664 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FJ455 UT WOS:A1991FJ45500017 ER PT J AU HERMAN, JR HUDSON, R MCPETERS, R STOLARSKI, R AHMAD, Z GU, XY TAYLOR, S WELLEMEYER, C AF HERMAN, JR HUDSON, R MCPETERS, R STOLARSKI, R AHMAD, Z GU, XY TAYLOR, S WELLEMEYER, C TI A NEW SELF-CALIBRATION METHOD APPLIED TO TOMS AND SBUV BACKSCATTERED ULTRAVIOLET DATA TO DETERMINE LONG-TERM GLOBAL OZONE CHANGE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB The currently archived (1989) total ozone mapping spectrometer (TOMS) and solar backscattered ultraviolet (SBUV) total ozone data (version 5) show a global average decrease of about 9.0% from November 1978 to November 1988. This large decrease disagrees with an approximate 3.5% decrease estimated from the ground-based Dobson network. The primary source of disagreement was found to arise from an overestimate of reflectivity change and its incorrect wavelengths dependence for the diffuser plate used when measuring solar irradiance. Both of these factors have led to an overestimate of the rate of atmospheric ozone depletion by SBUV and TOMS. For total ozone measured by TOMS, a means has been found to use the measured radiance-irradiance ratio from several wavelengths pairs to construct an internally self consistent calibration. The method uses the wavelength dependence of the sensitivity to calibration errors and the requirement that albedo ratios for each wavelength pair yield the same total ozone amounts. Smaller errors in determining spacecraft attitude, synchronization problems with the photon counting electronics, and sea glint contamination of boundary reflectivity data have been corrected or minimized. New climatological low-ozone profiles have been incorporated into the TOMS algorithm that are appropriate for Antarctic ozone hole conditions and other low ozone cases. The combined corrections have led to a new determination of the global average total ozone trend (version 6) as a 2.9 +/- 1.3% decrease over 11 years (October 1978 to November 1989). Version 6 data are shown to be in agreement within error limits with the average of 39 ground-based Dobson stations and with the world standard Dobson spectrometer 83 at Mauna Loa, Hawaii. The global average ozone trend from version 6 data shows the presence of varying short-period trends (1979 to 1983, -0.33%/yr; 1983 to 1986, -0.91% yr, and 1986 to 1990, +0.16%/yr) that are partially masked in the original version 5 trends. C1 ST SYST CORP, LANHAM, MD 20706 USA. RP HERMAN, JR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, GREENBELT, MD 20771 USA. RI Stolarski, Richard/B-8499-2013; McPeters, Richard/G-4955-2013; OI Stolarski, Richard/0000-0001-8722-4012; McPeters, Richard/0000-0002-8926-8462; Herman, Jay/0000-0002-9146-1632 NR 21 TC 117 Z9 119 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD APR 20 PY 1991 VL 96 IS D4 BP 7531 EP 7545 DI 10.1029/90JD02662 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FJ455 UT WOS:A1991FJ45500018 ER PT J AU NEUGEBAUER, M AF NEUGEBAUER, M TI THE QUASI-STATIONARY AND TRANSIENT STATES OF THE SOLAR-WIND SO SCIENCE LA English DT Article AB There are two states of the solar wind: quasi-stationary and transient. After 30 years of measurements by interplanetary spacecraft, the differences in the physical properties of the two types of wind are fairly well determined, but the physical processes involved in their accelerations are not yet understood in detail. The solar wind exists in part because the upper solar atmosphere, called the corona, is very hot, but the heating mechanisms are also not well understood. Recent research suggests a link between the heating and acceleration mechanisms. RP NEUGEBAUER, M (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 15 TC 15 Z9 15 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 APR 19 PY 1991 VL 252 IS 5004 BP 404 EP 409 DI 10.1126/science.252.5004.404 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FH103 UT WOS:A1991FH10300033 PM 17740939 ER PT J AU VINING, CB LASKOW, W HANSON, JO VANDERBECK, RR GORSUCH, PD AF VINING, CB LASKOW, W HANSON, JO VANDERBECK, RR GORSUCH, PD TI THERMOELECTRIC PROPERTIES OF PRESSURE-SINTERED SI0.8GE0.2 THERMOELECTRIC ALLOYS SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SILICON-GERMANIUM ALLOYS; BOUNDARY SCATTERING; GRAIN-BOUNDARIES; GE AB The thermoelectric properties of 28 sintered Si0.8 Ge0.2 alloys, heavily doped with either boron or phosphorus and prepared from powders with median particle sizes ranging from about 1-mu-m to over 100-mu-m, have been determined from 300 to 1300 K. The thermal conductivity decreases with decreasing particle size, however, the figure of merit is not significantly increased due to a compensating reduction in the electrical conductivity. The thermoelectric figure of merit is in good agreement with results of Dismukes et al. [J. Appl. Phys. 10, 2899 (1964)] on similarly doped alloys prepared by zone-leveling techniques. The electrical and thermal conductivity are found to be sensitive to preparation procedure while the Seebeck coefficient and figure of merit are much less sensitive. The high-temperature electrical properties are consistent with charge carrier scattering by acoustic or optical phonons. C1 GE,PHILADELPHIA,PA 19101. RP VINING, CB (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 33 TC 148 Z9 149 U1 7 U2 43 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 APR 15 PY 1991 VL 69 IS 8 BP 4333 EP 4340 DI 10.1063/1.348408 PN 1 PG 8 WC Physics, Applied SC Physics GA FL728 UT WOS:A1991FL72800025 ER PT J AU WENG, RS WU, JC KRYDER, MH AF WENG, RS WU, JC KRYDER, MH TI THE EFFECT OF RANDOM COERCIVITY ON DOMAIN GROWTH-PROCESSES IN RARE-EARTH TRANSITION-METAL ALLOYS SO JOURNAL OF APPLIED PHYSICS LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP WENG, RS (reprint author), CARNEGIE MELLON UNIV,CTR MAGNET TECHNOL,PITTSBURGH,PA 15213, USA. NR 2 TC 0 Z9 0 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD APR 15 PY 1991 VL 69 IS 8 BP 4856 EP 4856 DI 10.1063/1.348227 PN 2A PG 1 WC Physics, Applied SC Physics GA FL732 UT WOS:A1991FL73200143 ER PT J AU WU, JC KATTI, RR STADLER, HL AF WU, JC KATTI, RR STADLER, HL TI STRIPE STABILIZATION IN VERTICAL BLOCH LINE MEMORY SO JOURNAL OF APPLIED PHYSICS LA English DT Article; Proceedings Paper CT 35TH ANNUAL CONF ON MAGNETISM AND MAGNETIC MATERIALS CY OCT 29-NOV 01, 1990 CL SAN DIEGO, CA SP AMER INST PHYS, IEEE, MAGNET SOC, AMER INST MIN MET & PETR ENGINEERS, MET SOC, USN, OFF NAVAL RES, AMER SOC TESTING & MAT, AMER PHYS SOC, AMER CERAM SOC ID DOMAIN AB Partially grooved, long, rectangular grooves on the garnet surface were used to stabilize minor loop stripes in a vertical Bloch line memory. These stripes reside beneath the stripe confinement groove. The test chip contained 10 or 20 minor loop grooves, 10 read/write (r/w) gate grooves, and a major line groove. The film thickness was 4.76-mu-m, and the groove was 0.5-mu-m deep. Each minor loop groove was 500-mu-m long, four widths were tried: 3.5, 4, 4.5, and 5-mu-m. Two groove periods were tried: 10 and 20-mu-m. For stripe initialization, a bubble was nucleated in every minor loop groove by a single current pulse at a 90 Oe bias field. As the bias field was decreased slowly, bubbles began to stripe out at 80 Oe. At 75 Oe, all 10 stripes were stretched to the full groove length. These stripes were stable at bias fields between 70 and 80 Oe. Stripes decreased in length at higher fields, and escaped from the confinement groove at low fields. When stripes escaped from the groove, it always occured from the end not facing a r/w gate groove. These bias field values and the stripe-escape asymmetry are confirmed by computer simulation. RP WU, JC (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 12 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 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD APR 15 PY 1991 VL 69 IS 8 BP 5751 EP 5753 DI 10.1063/1.347910 PN 2B PG 3 WC Physics, Applied SC Physics GA FL735 UT WOS:A1991FL73500154 ER PT J AU WU, JC KATTI, RR STADLER, HL AF WU, JC KATTI, RR STADLER, HL TI MAJOR LINE OPERATION IN VERTICAL BLOCH LINE MEMORY SO JOURNAL OF APPLIED PHYSICS LA English DT Article; Proceedings Paper CT 35TH ANNUAL CONF ON MAGNETISM AND MAGNETIC MATERIALS CY OCT 29-NOV 01, 1990 CL SAN DIEGO, CA SP AMER INST PHYS, IEEE, MAGNET SOC, AMER INST MIN MET & PETR ENGINEERS, MET SOC, USN, OFF NAVAL RES, AMER SOC TESTING & MAT, AMER PHYS SOC, AMER CERAM SOC AB The operation of a major line in a vertical Bloch line memory using a partial garnet grooving architecture was studied experimentally and numerically. The major line was fabricated on a 5-mu-m bubble garnet using three conductor layers and a 10% garnet grooving. The major line contains a bubble generator, a bubble propagation track, a bubble expander for bubble detection, and a bubble annihilator. The minimum current for bubble generation was 350 mA, at 50 ns pulse width. The bubble propagation track was a typical dual conductor design with a 5-mu-m-wide conductor and a 20-mu-m circuit period. The minimum drive current was 5 and 10 mA at an operating frequency of 250 and 500 kHz, respectively. The bias field margin was from 84 to 100 Oe. The bubble expander was a modification of the propagation track. The meandering conductor and the groove width were gradually increased to stretch the bubble into a stripe. The bias field margin was from 82 to 84 Oe. The numerical model includes the effect of the garnet grooving, and the simulation results agree with the experimental data. RP WU, JC (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 8 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 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD APR 15 PY 1991 VL 69 IS 8 BP 5754 EP 5756 DI 10.1063/1.347911 PN 2B PG 3 WC Physics, Applied SC Physics GA FL735 UT WOS:A1991FL73500155 ER PT J AU SEN, AD HUNTRESS, WT ANICICH, VG MCEWAN, MJ DENISON, AB AF SEN, AD HUNTRESS, WT ANICICH, VG MCEWAN, MJ DENISON, AB TI ASSOCIATION REACTIONS AT LOW-PRESSURE .4. THE HC3N+/HC3N SYSTEM SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID ION-MOLECULE REACTIONS; FLOW TUBE; CYANOACETYLENE; RATES; HC3N AB The reactions between HC3N+ and HC3N, and between HC5N+ and HC3N have been examined at pressures from 1 x 10(-7) to 1 x 10(-3) Torr by ion cyclotron resonance mass spectrometry. The reaction between HC3N+ and HC3N has both a bimolecular reaction path and a termolecular reaction path. The overall bimolecular reaction rate coefficient was found to be 1.3 x 10(-9) cm3 s-1. The primary product, HC5N+, represents 90% of the product ions, while the minor products HC6N2+ and H2C6N2+ each represent 5%. The termolecular association rate coefficient was 3.7 x 10(-24) cm6 s-1 with He as the third body. From double resonance experiments the mean lifetime of the collision complex was determined to be 180-mu-s. HC5N+ was found to react with HC3N and form the adduct ion H2C8N2+ through both bimolecular and termolecular channels. The bimolecular rate coefficient was 5.0 x 10(-10) cm3 s-1 and the termolecular rate coefficient was observed to be 1.2 x 10(-22) cm6 s-1 with HC3N as the third body. With He as the stabilizing molecule, the termolecular rate coefficient was 6.0 x 10(-24) cm6 s-1. The mean unimolecular lifetime of the collision complex was estimated to be greater-than-or-equal-to 15-mu-s and the mean radiative lifetime for the radiative association channel was found to be greater-than-or-equal-to 89-mu-s. HC5N+ was found to be formed with excess internal energy and did not react by bimolecular association until relaxed by several nonreactive collisions with HC3N. C1 UNIV CANTERBURY, DEPT CHEM, CHRISTCHURCH 1, NEW ZEALAND. UNIV WYOMING, DEPT PHYS & ASTRON, LARAMIE, WY 82071 USA. RP CALTECH, JET PROP LAB, MS 183-601, PASADENA, CA 91109 USA. NR 37 TC 23 Z9 23 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-9606 EI 1089-7690 J9 J CHEM PHYS JI J. Chem. Phys. PD APR 15 PY 1991 VL 94 IS 8 BP 5462 EP 5470 DI 10.1063/1.460481 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FH076 UT WOS:A1991FH07600026 ER PT J AU POHORILLE, A BENJAMIN, I AF POHORILLE, A BENJAMIN, I TI MOLECULAR-DYNAMICS OF PHENOL AT THE LIQUID VAPOR INTERFACE OF WATER SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID 2ND HARMONIC-GENERATION; SURFACE; ORIENTATION; SIMULATION; BENZENE AB Molecular dynamics results are presented for phenol at the water liquid-vapor interface at 300 K. The calculated excess free energy of phenol at the interface is -2.8 +/- 0.4 kcal/mol, in good agreement with the recent experimental results of Eisenthal and co-workers. The most probable orientation of the phenol molecule at the surface is such that the aromatic ring is perpendicular to the interface and the OH group is fully immersed in water. The hydroxyl substituent has a preferred orientation which is similar to the orientation of OH bonds of water at the pure water liquid-vapor interface. The transition between interfacial and bulk-like behavior of phenol is abrupt and occurs when the center of mass of the solute is located about 6 angstrom from the Gibbs surface of water. In this region the para carbon atom of the hydrophobic benzene ring can reach the interface and become partially dehydrated. This result suggests that the width of the interfacial region in which the behavior of a simple amphiphilic solute in water is influenced by the presence of the surface depends primarily on the size of its hydrophobic part. The role of the OH substituent was investigated by comparing phenol at the interface with two model systems: benzene with and without partial changes on carbon and hydrogen atoms. It is shown that in the absence of the hydrophilic substituent the solute is located further away from the liquid phase and is more likely to be oriented parallel to the interface. However, when the center of mass of the solute is moved into the interfacial region where the density of water approaches that of the bulk solvent, all three molecules become oriented perpendicularly to the surface. In this orientation the work of cavity formation needed to accommodate the hydrophobic ring in aqueous solvent is minimized. C1 UNIV CALIF SANTA CRUZ,DEPT CHEM,SANTA CRUZ,CA 95064. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP POHORILLE, A (reprint author), UNIV CALIF BERKELEY,DEPT CHEM,BERKELEY,CA 94720, USA. FU NCI NIH HHS [NCA-2 315] NR 41 TC 76 Z9 76 U1 0 U2 8 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 APR 15 PY 1991 VL 94 IS 8 BP 5599 EP 5605 DI 10.1063/1.460496 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FH076 UT WOS:A1991FH07600041 PM 11540075 ER PT J AU WHITTENBERGER, JD KUMAR, KS MANNAN, SK AF WHITTENBERGER, JD KUMAR, KS MANNAN, SK TI 1000-K TO 1300-K SLOW PLASTIC COMPRESSION PROPERTIES OF AL-DEFICIENT NIAL SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID FLOW PROPERTIES; GRAIN-SIZE; DEPENDENCE; TEMPERATURE; PHASE; NI3AL; CREEP AB Nickel aluminides containing 37, 38.5 and 40 at % Al have been fabricated by XD(tm) synthesis and hot pressing. Such materials were compression tested in air under constant velocity conditions between 1000 and 1300 K. Examination of the microstructures of hot pressed and compression tested aluminides indicated that the structure consisted of two phases, gamma' and NiAl, for essentially all conditions, where gamma' was usually found on the NiAl grain boundaries. The stress-strain behaviour of all three intermetallics was similar where flow at a nominally constant stress occurred after about two plastic per cent deformation. Furthermore the 1000 to 1300 K flow stress-strain rate properties are nearly identical for these materials, and they are much lower than those for XD(tm) processed Ni-50Al [1]. The overall deformation of the two phase nickel aluminides appears to be controlled by dislocation climb in NiAl rather than processes in gamma'. C1 MARTIN MARIETTA CORP LABS,BALTIMORE,MD 21227. RP WHITTENBERGER, JD (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 18 TC 7 Z9 7 U1 0 U2 1 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD APR 15 PY 1991 VL 26 IS 8 BP 2015 EP 2022 DI 10.1007/BF00549160 PG 8 WC Materials Science, Multidisciplinary SC Materials Science GA FH280 UT WOS:A1991FH28000004 ER PT J AU PASCARELLE, SM OWENS, A GEHRELS, N TEEGARDEN, BJ AF PASCARELLE, SM OWENS, A GEHRELS, N TEEGARDEN, BJ TI GEOMETRY DEPENDENCE OF THE EMPIRICAL RELATIONSHIP BETWEEN VOLUME AND EFFICIENCY FOR GE DETECTORS SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT LA English DT Letter AB We have tested the suggestion of Zhong that the slope of the efficiency curve is nearly independent of the angle of incidence of the illuminating source and the detector height-to-diameter ratio. Within the chosen range of energies and ratios, the slope is found to be constant within approximately 3%, but for larger ranges, it may vary by as much as 10% as a function of angle of incidence and 56% as a function of height-to-diameter ratio. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RI Gehrels, Neil/D-2971-2012 NR 5 TC 1 Z9 1 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 APR 15 PY 1991 VL 302 IS 2 BP 388 EP 389 DI 10.1016/0168-9002(91)90429-T PG 2 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Nuclear; Physics, Particles & Fields SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA FN899 UT WOS:A1991FN89900027 ER PT J AU DENIER, JP HALL, P SEDDOUGUI, SO AF DENIER, JP HALL, P SEDDOUGUI, SO TI ON THE RECEPTIVITY PROBLEM FOR GORTLER VORTICES - VORTEX MOTIONS INDUCED BY WALL ROUGHNESS SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article ID GROWING BOUNDARY-LAYERS; NONLINEAR DEVELOPMENT; GROWTH; FLOWS AB The receptivity problem for Gortler vortices induced by wall roughness is investigated. The roughness is modelled by small amplitude perturbations to the curved wall over which the flow takes place. The amplitude of these perturbations is taken to be sufficiently small for the induced Gortler vortices to be described by linear theory. The roughness is assumed to vary in the spanwise direction on the boundary-layer lengthscale, whilst in the flow direction the corresponding variation is on the lengthscale over which the wall curvature varies. In fact the latter condition can be relaxed to allow for a faster streamwise roughness variation so long as the variation does not become as fast as that in the spanwise direction. The function that describes the roughness is assumed to be such that its spanwise and streamwise dependences can be separated; this enables us to make progress by taking Fourier or Laplace transforms where appropriate. The cases of isolated and distributed roughness elements are investigated and the coupling coefficient which relates the amplitude of the forcing and the induced vortex amplitude is found asymptotically in the small wavelength limit. It is shown that this coefficient is exponentially small in the latter limit so that it is unlikely that this mode can be stimulated directly by wall roughness. The situation at O(1) wavelengths is quite different and this is investigated numerically for different forcing functions. It is found that an isolated roughness element induces a vortex field which grows within a wedge at a finite distance downstream of the element. However, immediately downstream of the obstacle the disturbed flow produced by the element decays in amplitude. The receptivity problem at larger Gortler numbers appropriate to relatively large wall curvature is discussed in detail. It is found that the fastest growing linear mode of the Gortler instability equations has wavenumber proportional to the one-fifth power of the Gortler number. The mode can be related to both inviscid disturbances and the disturbances appropriate to the right-hand branch of the neutral curve for Gortler vortices. The coupling coefficient between this, the fastest growing vortex, and the forcing function is found in closed form. C1 NASA,LANGLEY RES CTR,INST COMP APPL SCI & ENGN,HAMPTON,VA 23665. RP DENIER, JP (reprint author), UNIV EXETER,DEPT MATH,N PARK RD,EXETER EX4 4QE,DEVON,ENGLAND. RI Stephen, Sharon/B-1011-2016 OI Stephen, Sharon/0000-0001-8204-8419 NR 22 TC 63 Z9 63 U1 0 U2 1 PU ROYAL SOC LONDON PI LONDON PA 6 CARLTON HOUSE TERRACE, LONDON, ENGLAND SW1Y 5AG J9 PHILOS T ROY SOC A JI Philos. Trans. R. Soc. Lond. Ser. A-Math. Phys. Eng. Sci. PD APR 15 PY 1991 VL 335 IS 1636 BP 51 EP 85 DI 10.1098/rsta.1991.0036 PG 35 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FH549 UT WOS:A1991FH54900002 ER PT J AU WALBERG, GD AF WALBERG, GD TI HYPERSONIC FLIGHT EXPERIENCE SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES LA English DT Article ID SPACE-SHUTTLE ORBITER; AERODYNAMIC COMPARISONS; ENTRY; PREDICTIONS RP WALBERG, GD (reprint author), NASA,LANGLEY RES CTR,GEORGE WASHINGTON UNIV,JOINT INST ADV FLIGHT SCI,HAMPTON,VA 23665, USA. NR 44 TC 4 Z9 4 U1 0 U2 2 PU ROYAL SOC LONDON PI LONDON PA 6 CARLTON HOUSE TERRACE, LONDON, ENGLAND SW1Y 5AG J9 PHILOS T ROY SOC A JI Philos. Trans. R. Soc. Lond. Ser. A-Math. Phys. Eng. Sci. PD APR 15 PY 1991 VL 335 IS 1637 BP 91 EP 119 DI 10.1098/rsta.1991.0038 PG 29 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FK627 UT WOS:A1991FK62700002 ER PT J AU VASQUEZ, RP HOUSLEY, RM AF VASQUEZ, RP HOUSLEY, RM TI STUDY OF CHEMICALLY-ETCHED BI2SR2-XCA1+XCU2O8+DELTA SURFACES SO PHYSICA C LA English DT Article ID CA-CU-O; PHOTOELECTRON-SPECTROSCOPY; ELECTRONIC-STRUCTURE; SINGLE-CRYSTAL; PHOTOEMISSION; YBA2CU3O7-X AB X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) are used to characterize the surfaces of polycrystalline Bi2Sr(2-x)Ca(1+x)Cu2O8+delta thin films which have been chemically etched in a solution of Br2 in absolute ethanol. XPS measurements from individual grains (approximately 1 mm2) are obtained, and the spectra presented here are comparable to spectra in the literature obtained from single crystals cleaved in vacuum. XPS valence band spectra show a clear Fermi edge, indicating that the room temperature conductivity near the surface is metallic. This is the first report of a detectable Fermi edge from a high temperature superconductor surface which has not been treated in vacuum. C1 ROCKWELL INT CORP,CTR SCI,THOUSAND OAKS,CA 91360. CALTECH,DEPT PHYS,PASADENA,CA 91125. RP VASQUEZ, RP (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 29 TC 16 Z9 16 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-4534 J9 PHYSICA C JI Physica C PD APR 15 PY 1991 VL 175 IS 3-4 BP 233 EP 240 DI 10.1016/0921-4534(91)90592-M PG 8 WC Physics, Applied SC Physics GA FJ347 UT WOS:A1991FJ34700001 ER PT J AU GOLDMAN, C AF GOLDMAN, C TI LONG-RANGE ELECTRON-TRANSFER IN PROTEINS - A RENORMALIZED-PERTURBATION-EXPANSION APPROACH SO PHYSICAL REVIEW A LA English DT Article ID BIOLOGICAL MOLECULES AB An efficient algorithm for calculating the electronic matrix element T(DA) for electron-transfer reactions between a donor D and acceptor A in biological systems is presented. The tight-binding Hamiltonian and the Green's-function formalism are used to obtain T(DA) via the renormalized-perturbation expansion. This procedure permits taking into account the detailed structure of the array provided by the specific protein that assists the electron transfer. As an application, results are presented for the calculation of some of these matrix elements in metal-labeled myoglobin, and comparison with experimental data is made. By analyzing the self-energies at each site of the array, these results can be understood as a small-denominator effect. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP GOLDMAN, C (reprint author), CALTECH,DEPT CHEM,PASADENA,CA 91125, USA. NR 25 TC 56 Z9 56 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD APR 15 PY 1991 VL 43 IS 8 BP 4500 EP 4509 DI 10.1103/PhysRevA.43.4500 PG 10 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA FH612 UT WOS:A1991FH61200047 ER PT J AU BORENSTAIN, SI GRAVE, I LARSSON, A RICH, DH JONSSON, B ANDERSSON, I WESTIN, J ANDERSSON, T AF BORENSTAIN, SI GRAVE, I LARSSON, A RICH, DH JONSSON, B ANDERSSON, I WESTIN, J ANDERSSON, T TI LONG-WAVELENGTH INFRARED-SPECTROSCOPY OF AN ASYMMETRICALLY STRUCTURED GA0.6AL0.4AS GAAS SUPERLATTICE SO PHYSICAL REVIEW B LA English DT Note ID QUANTUM WELL STRUCTURE; INTERSUBBAND TRANSITIONS; ELECTRIC-FIELD; MU-M; ABSORPTION; BAND; LASER AB A long-wavelength infrared (LWIR) spectroscopic study of a doped multiple-quantum-well (MQW) structure, where each quantum well is clad by asymmetrically structured superlattices, is reported. The measured absorption and photocurrent spectra differ markedly from those of a MQW LWIR detector with conventional flat barriers. Different electron subband states are introduced, and the transition e 1-e3, which in a flat-barrier MQW is normally forbidden, becomes the dominant transition; thus bringing about an extremely broad photoresponse band (DELTA-lambda/lambda almost-equal-to 0.6), centered at 5-mu-m. This system also exhibits direct evidence of photon-assisted resonant tunneling. It is manifested by a distinct peak and negative differential photoconductance in the photocurrent-vs-bias-voltage characteristics when the structure is exposed to a CO2 9.5-mu-m laser line. All these effects are explained by the dependence of the electronic eigenstate spectrum on the electric field, calculated by solving the Schrodinger equation using the transfer-matrix method. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CHALMERS UNIV TECHNOL,S-41296 GOTHENBURG,SWEDEN. RP BORENSTAIN, SI (reprint author), CALTECH,DEPT APPL PHYS,PASADENA,CA 91125, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 23 TC 3 Z9 3 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0163-1829 J9 PHYS REV B JI Phys. Rev. B PD APR 15 PY 1991 VL 43 IS 11 BP 9320 EP 9323 DI 10.1103/PhysRevB.43.9320 PG 4 WC Physics, Condensed Matter SC Physics GA FH291 UT WOS:A1991FH29100071 ER PT J AU BONTING, SL AF BONTING, SL TI NEEDS FOR BIOSENSORS IN SPACE BIOLOGY RESEARCH SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES INST,SETI INST,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 1 EP SCHB PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG894 UT WOS:A1991FG89401397 ER PT J AU MIYOSHI, K ALTEROVITZ, SA POUCH, JJ AF MIYOSHI, K ALTEROVITZ, SA POUCH, JJ TI EVALUATION AND SURFACE-ANALYSIS OF SOLID LUBRICATING FILMS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 12 EP COLL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG893 UT WOS:A1991FG89301033 ER PT J AU POWELL, SC KIEFER, RL PATE, PL ORWOLL, RA LONG, SAT AF POWELL, SC KIEFER, RL PATE, PL ORWOLL, RA LONG, SAT TI THE EFFECTS OF ATOMIC OXYGEN AND ULTRAVIOLET-RADIATION ON 2 ARAMID MATERIALS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 COLL WILLIAM & MARY,DEPT CHEM,WILLIAMSBURG,VA 23185. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 45 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG894 UT WOS:A1991FG89400861 ER PT J AU FEWELL, LL AF FEWELL, LL TI ATOMIC-OXYGEN INDUCED STRUCTURAL-CHANGES IN POLYPHOSPHAZENE FILMS AND COATINGS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 52 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG894 UT WOS:A1991FG89400868 ER PT J AU COYNE, LM AF COYNE, LM TI REFLECTANCE SIGNATURE OF TRAPPED HOLES USING NEAR-INFRARED REFLECTANCE SPECTROSCOPY (NIRA) AND EPR SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 57 EP COLL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG893 UT WOS:A1991FG89301078 ER PT J AU PAGANO, S KRISHNAN, PN BIRENZVIGE, A NESBITT, F AF PAGANO, S KRISHNAN, PN BIRENZVIGE, A NESBITT, F TI XPS ANALYSIS OF METALLIC IMPREGNANTS ON ACTIVATED-CHARCOAL SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. USA,CTR CHEM RES DEV & ENGN,ABERDEEN PROVING GROUND,MD 21010. COPPIN STATE COLL,DEPT NAT SCI,BALTIMORE,MD 21216. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 89 EP COLL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG893 UT WOS:A1991FG89301110 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H AF BAUSCHLICHER, CW LANGHOFF, SR PARTRIDGE, H TI STUDY OF METAL-LIGAND BONDING SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 111 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG894 UT WOS:A1991FG89400616 ER PT J AU MUIRHEAD, BK EBERLEIN, SJ BRADLEY, JG KAISER, WJ AF MUIRHEAD, BK EBERLEIN, SJ BRADLEY, JG KAISER, WJ TI SPACE TECHNOLOGY FOR APPLICATION TO TERRESTRIAL HAZARDOUS MATERIALS ANALYSIS AND ACQUISITION SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 157 EP ENVR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG893 UT WOS:A1991FG89301539 ER PT J AU MARDER, SR BERATAN, DN CHENG, LT TIEMANN, BG AF MARDER, SR BERATAN, DN CHENG, LT TIEMANN, BG TI OPTIMIZING THE 2ND-ORDER OPTICAL NONLINEARITIES OF ORGANIC-MOLECULES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91125. DUPONT CO,EXPT STN,WILMINGTON,DE 19898. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 163 EP INOR PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG893 UT WOS:A1991FG89302058 ER PT J AU KOJIRO, DR WOELLER, FH TAKEUCHI, N HUMPHRY, DE AF KOJIRO, DR WOELLER, FH TAKEUCHI, N HUMPHRY, DE TI A MICROVOLUME METASTABLE IONIZATION DETECTOR FOR THE ANALYSIS OF PLANETARY-ATMOSPHERES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 TMA NORCAL,RICHMOND,CA 94804. SETI INST,MT VIEW,CA 94043. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 198 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG893 UT WOS:A1991FG89300396 ER PT J AU KOJIRO, DR CARLE, GC OBERBECK, VR OHARA, BJ VALENTIN, JR SCATTERGOOD, TW COHEN, MJ AF KOJIRO, DR CARLE, GC OBERBECK, VR OHARA, BJ VALENTIN, JR SCATTERGOOD, TW COHEN, MJ TI ANALYTICAL CONCEPTS FOR THE INSITU ANALYSIS OF EXTRATERRESTRIAL ENVIRONMENTS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SUNY STONY BROOK,STONY BROOK,NY 11794. PCP INC,W PALM BEACH,FL 33409. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 199 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG893 UT WOS:A1991FG89300397 ER PT J AU SHEN, TC AF SHEN, TC TI CHARACTERIZATION AND DEVELOPMENT OF SILICONE GC COLUMN SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,SETI INST,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 204 EP ANYL PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG893 UT WOS:A1991FG89300402 ER PT J AU DOROGY, WE STCLAIR, AK AF DOROGY, WE STCLAIR, AK TI LOW DIELECTRIC POLYIMIDE FIBERS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 217 EP PMSE PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG894 UT WOS:A1991FG89401383 ER PT J AU WINGARD, CD PATTERSON, WJ AF WINGARD, CD PATTERSON, WJ TI THE USE OF PHOTO-ELECTRON EMISSION TO DETERMINE THE EFFECTS OF CONTAMINATION ON BOND STRENGTH AND INTEGRITY OF METAL POLYMER COMPOSITE SPECIMENS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,MAT & PROC LAB EH33,HUNTSVILLE,AL 35812. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 222 EP PMSE PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG894 UT WOS:A1991FG89401388 ER PT J AU STANCIL, PC LONG, ER LONG, SAT HARRIES, WL AF STANCIL, PC LONG, ER LONG, SAT HARRIES, WL TI EFFECTS OF ATOMIC OXYGEN ON 2 POLYIMIDES AND THEIR CARBON-FIBER-REINFORCED COMPOSITES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. OLD DOMINION UNIV,DEPT PHYS,NORFOLK,VA 23529. NR 0 TC 0 Z9 0 U1 1 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 350 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG894 UT WOS:A1991FG89401158 ER PT J AU SMITH, JG CONNELL, JW HERGENROTHER, PM AF SMITH, JG CONNELL, JW HERGENROTHER, PM TI POLY(ARYLENE ETHER-BENZOXAZOLE)S SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 14 PY 1991 VL 201 BP 351 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA FG894 UT WOS:A1991FG89401159 ER PT J AU BINDSCHADLER, RA SCAMBOS, TA AF BINDSCHADLER, RA SCAMBOS, TA TI SATELLITE-IMAGE-DERIVED VELOCITY-FIELD OF AN ANTARCTIC ICE STREAM SO SCIENCE LA English DT Article AB The surface velocity of a rapidly moving ice stream has been determined to high accuracy and spatial density with the use of sequential satellite imagery. Variations of ice velocity are spatially related to surface undulations, and transverse velocity variations of up to 30 percent occur. Such large variations negate the concept of plug flow and call into question earlier mass-balance calculations for this and other ice streams where sparse velocity data were used. The coregistration of images with the use of the topographic undulations of the ice stream and the measurement of feature displacement with cross-correlation of image windows provide significant improvements in the use of satellite imagery for ice-flow determination. C1 ST SYST CORP,LANHAM,MD 20706. RP BINDSCHADLER, RA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 971,GREENBELT,MD 20771, USA. RI Scambos, Ted/B-1856-2009 NR 23 TC 98 Z9 101 U1 1 U2 14 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 12 PY 1991 VL 252 IS 5003 BP 242 EP 246 DI 10.1126/science.252.5003.242 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FG036 UT WOS:A1991FG03600037 PM 17769268 ER PT J AU SAUNDERS, RS PETTENGILL, GH AF SAUNDERS, RS PETTENGILL, GH TI MAGELLAN - MISSION SUMMARY SO SCIENCE LA English DT Article AB The Magellan radar mapping mission is in the process of producing a global, high-resolution image and altimetry data set of Venus. Despite initial communications problems, few data gaps have occurred. Analysis of Magellan data is in the initial stages. The radar system data are of high quality, and the planned performance is being achieved in terms of spatial resolution and geometric and radiometric accuracy. Image performance exceeds expectations, and the image quality and mosaickability are extremely good. Future plans for the mission include obtaining gravity data, filling gaps in the initial map, and conducting special studies with the radar. C1 MIT,CAMBRIDGE,MA 02139. RP SAUNDERS, RS (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 7 TC 25 Z9 25 U1 0 U2 5 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 12 PY 1991 VL 252 IS 5003 BP 247 EP 249 DI 10.1126/science.252.5003.247 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FG036 UT WOS:A1991FG03600038 PM 17769269 ER PT J AU SAUNDERS, RS ARVIDSON, RE HEAD, JW SCHABER, GG STOFAN, ER SOLOMON, SC AF SAUNDERS, RS ARVIDSON, RE HEAD, JW SCHABER, GG STOFAN, ER SOLOMON, SC TI AN OVERVIEW OF VENUS GEOLOGY SO SCIENCE LA English DT Article ID BETA-REGIO; VENERA-16 DATA; RADAR IMAGES; SURFACE; VOLCANISM; STYLES AB The Magellan spacecraft is producing comprehensive image and altimetry data for the planet Venus. Initial geologic mapping of the planet reveals a surface dominated by volcanic plains and characterized by extensive volcanism and tectonic deformation. Geologic and geomorphologic units include plains terrains, tectonic terrains, and surficial material units. Understanding the origin of these units and the relation between them is an ongoing task of the Magellan team. C1 WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. BROWN UNIV,DEPT GEOL SCI,PROVIDENCE,RI 02912. US GEOL SURVEY,FLAGSTAFF,AZ 86001. RP SAUNDERS, RS (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 36 TC 31 Z9 31 U1 0 U2 8 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 12 PY 1991 VL 252 IS 5003 BP 249 EP 252 DI 10.1126/science.252.5003.249 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FG036 UT WOS:A1991FG03600039 PM 17769270 ER PT J AU PETTENGILL, GH FORD, PG JOHNSON, WTK RANEY, RK SODERBLOM, LA AF PETTENGILL, GH FORD, PG JOHNSON, WTK RANEY, RK SODERBLOM, LA TI MAGELLAN - RADAR PERFORMANCE AND DATA PRODUCTS SO SCIENCE LA English DT Article AB The Magellan Venus orbiter carries only one scientific instrument: a 12.6-centimeter-wavelength radar system shared among three data-taking modes. The synthetic-aperture mode images radar echoes from the Venus surface at a resolution of between 120 and 300 meters, depending on spacecraft altitude. In the altimetric mode, relative height measurement accuracies may approach 5 meters, depending on the terrain's roughness, although orbital uncertainties place a floor of about 50 meters on the absolute uncertainty. In areas of extremely rough topography, accuracy is limited by the inherent line-of-sight radar resolution of about 88 meters. The maximum elevation observed to date, corresponding to a planetary radius of 6062 kilometers, lies within Maxwell Mons. When used as a thermal emission radiometer, the system can determine surface emissivities to an absolute accuracy of about 0.02. Mosaicked and archival digital data products will be released in compact disk (CDROM) format. C1 CANADA CTR REMOTE SENSING,OTTAWA K1A 0Y7,ONTARIO,CANADA. CALTECH,JET PROP LAB,PASADENA,CA 91109. US GEOL SURVEY,FLAGSTAFF,AZ 86001. RP PETTENGILL, GH (reprint author), MIT,CAMBRIDGE,MA 02139, USA. NR 7 TC 87 Z9 87 U1 0 U2 7 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 12 PY 1991 VL 252 IS 5003 BP 260 EP 265 DI 10.1126/science.252.5003.260 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FG036 UT WOS:A1991FG03600041 PM 17769272 ER PT J AU TYLER, GL FORD, PG CAMPBELL, DB ELACHI, C PETTENGILL, GH SIMPSON, RA AF TYLER, GL FORD, PG CAMPBELL, DB ELACHI, C PETTENGILL, GH SIMPSON, RA TI MAGELLAN - ELECTRICAL AND PHYSICAL-PROPERTIES OF VENUS SURFACE SO SCIENCE LA English DT Article ID RESOLUTION RADAR DATA; SCATTERING LAWS; VENERA-16 DATA; IMAGES; STYLES; TOPOGRAPHY; VOLCANISM AB Magellan probes Venus' surface by 12.6-cm-wavelength vertical and oblique radar scattering and measures microwave thermal emission. Emissivity and root-mean-square slope maps between 330-degrees and 30-degrees-E and 90-degrees-N and 80-degrees-S are dissimilar, although some local features are exceptions. Inferred surface emissivities typically are approximately 0.85, but vary from approximately 0.35 at Maxwell to approximately 0.95 northeast of Gula Mons and other locations. Lowest emissivities appear in topographically high areas; this relation suggests that a phase change or differences in chemical weathering occur at about 6055-kilometer radius. Initial results indicate that there are significant variations in the surface scattering function. C1 MIT,CAMBRIDGE,MA 02139. CORNELL UNIV,ITHACA,NY 14853. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP TYLER, GL (reprint author), STANFORD UNIV,STANFORD,CA 94305, USA. NR 47 TC 37 Z9 37 U1 1 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 12 PY 1991 VL 252 IS 5003 BP 265 EP 270 DI 10.1126/science.252.5003.265 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FG036 UT WOS:A1991FG03600042 PM 17769273 ER PT J AU ARVIDSON, RE BAKER, VR ELACHI, C SAUNDERS, RS WOOD, JA AF ARVIDSON, RE BAKER, VR ELACHI, C SAUNDERS, RS WOOD, JA TI MAGELLAN - INITIAL ANALYSIS OF VENUS SURFACE MODIFICATION SO SCIENCE LA English DT Article ID IMPACT CRATERS; RADAR IMAGES; VOLCANISM; VENERA-15 AB Initial Magellan observations reveal a planet with high dielectric constant materials exposed preferentially in elevated regions with high slopes, ejecta deposits extending up to 1000 kilometers to the west of several impact craters, windblown deposits and features in areas where there are both obstacles and a source of particulate material, and evidence for slow, steady degradation by atmosphere-surface interactions and mass movements. C1 UNIV ARIZONA,DEPT GEOSCI,TUCSON,AZ 85721. CALTECH,JET PROP LAB,PASADENA,CA 91109. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP ARVIDSON, RE (reprint author), WASHINGTON UNIV,MCDONNELL CTR SPACE SCI,CTR SPACE SCI,ST LOUIS,MO 63130, USA. NR 25 TC 43 Z9 44 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 12 PY 1991 VL 252 IS 5003 BP 270 EP 275 DI 10.1126/science.252.5003.270 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FG036 UT WOS:A1991FG03600043 PM 17769274 ER PT J AU HEAD, JW CAMPBELL, DB ELACHI, C GUEST, JE MCKENZIE, DP SAUNDERS, RS SCHABER, GG SCHUBERT, G AF HEAD, JW CAMPBELL, DB ELACHI, C GUEST, JE MCKENZIE, DP SAUNDERS, RS SCHABER, GG SCHUBERT, G TI VENUS VOLCANISM - INITIAL ANALYSIS FROM MAGELLAN DATA SO SCIENCE LA English DT Article ID FLOW; EMPLACEMENT AB Magellan images confirm that volcanism is widespread and has been fundamentally important in the formation and evolution of the crust of Venus. High-resolution imaging data reveal evidence for intrusion (dike formation and cryptodomes) and extrusion (a wide range of lava flows). Also observed are thousands of small shield volcanoes, larger edifices up to several hundred kilometers in diameter, massive outpourings of lavas, and local pyroclastic deposits. Although most features are consistent with basaltic compositions, a number of large pancake-like domes are morphologically similar to rhyolite-dacite domes on Earth. Flows and sinuous channels with lengths of many hundreds of kilometers suggest that extremely high effusion rates or very fluid magmas (perhaps komatiites) may be present. Volcanism is evident in various tectonic settings (coronae, linear extensional and compressional zones, mountain belts, upland rises, highland plateaus, and tesserae). Volcanic resurfacing rates appear to be low (less than 2 km3/yr) but the significance of dike formation and intrusions, and the mode of crustal formation and loss remain to be established. C1 UCL, UNIV LONDON OBSERV, LONDON NW7 2QS, ENGLAND. UNIV CAMBRIDGE, DEPT EARTH SCI, CAMBRIDGE CB3 0EZ, ENGLAND. CORNELL UNIV, DEPT ASTRON, ITHACA, NY 14853 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. US GEOL SURVEY, FLAGSTAFF, AZ 86001 USA. UNIV CALIF LOS ANGELES, INST GEOPHYS & PLANETARY PHYS, DEPT EARTH & SPACE SCI, LOS ANGELES, CA 90024 USA. RP HEAD, JW (reprint author), BROWN UNIV, DEPT GEOL SCI, PROVIDENCE, RI 02912 USA. NR 82 TC 94 Z9 94 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD APR 12 PY 1991 VL 252 IS 5003 BP 276 EP 288 DI 10.1126/science.252.5003.276 PG 13 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FG036 UT WOS:A1991FG03600044 PM 17769275 ER PT J AU PHILLIPS, RJ ARVIDSON, RE BOYCE, JM CAMPBELL, DB GUEST, JE SCHABER, GG SODERBLOM, LA AF PHILLIPS, RJ ARVIDSON, RE BOYCE, JM CAMPBELL, DB GUEST, JE SCHABER, GG SODERBLOM, LA TI IMPACT CRATERS ON VENUS - INITIAL ANALYSIS FROM MAGELLAN SO SCIENCE LA English DT Article ID VENERA-16 SPACECRAFT; RADAR IMAGES; CONTINUATION; RATES AB Magellan radar images of 15 percent of the planet show 135 craters of probable impact origin. Craters more than 15 km across tend to contain central peaks, multiple central peaks, and peak rings. Many craters smaller than 15 km exhibit multiple floors or appear in clusters; these phenomena are attributed to atmospheric breakup of incoming meteoroids. Additionally, the atmosphere appears to have prevented the formation of primary impact craters smaller than about 3 km and produced a deficiency in the number of craters smaller than about 25 km across. Ejecta is found at greater distances than that predicted by simple ballistic emplacement, and the distal ends of some ejecta deposits are lobate. These characteristics may represent surface flows of material initially entrained in the atmosphere. Many craters are surrounded by zones of low radar albedo whose origin may have been deformation of the surface by the shock or pressure wave associated with the incoming meteoroid. Craters are absent from several large areas such as a 5 million square kilometer region around Sappho Patera, where the most likely explanation for the dearth of craters is volcanic resurfacing. There is apparently a spectrum of surface ages on Venus ranging approximately from 0 to 800 million years, and therefore Venus must be a geologically active planet. C1 UNIV LONDON OBSERV,LONDON NW7 2QS,ENGLAND. WASHINGTON UNIV,MCDONNELL CTR SPACE SCI,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130. NASA,DIV SOLAR SYST EXPLORAT,WASHINGTON,DC 20546. CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853. US GEOL SURVEY,FLAGSTAFF,AZ 86001. RP PHILLIPS, RJ (reprint author), SO METHODIST UNIV,DEPT GEOL SCI,DALLAS,TX 75275, USA. NR 50 TC 87 Z9 87 U1 0 U2 8 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 12 PY 1991 VL 252 IS 5003 BP 288 EP 297 DI 10.1126/science.252.5003.288 PG 10 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FG036 UT WOS:A1991FG03600045 PM 17769276 ER PT J AU ANSARI, H LESH, JR AF ANSARI, H LESH, JR TI SUPERFINE RESOLUTION ACOUSTOOPTIC SPECTRUM ANALYSIS SO APPLIED OPTICS LA English DT Article DE SPECTRUM ANALYSIS; ACOUSTOOPTIC; BRAGG CELLS AB We demonstrate the feasibility of 3-D acoustooptic spectrum analysis with ultrahigh resolution. Sub-Hertz resolution is achieved by processing over a sequence of CCD frames. RP ANSARI, H (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 8 TC 3 Z9 3 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD APR 10 PY 1991 VL 30 IS 11 BP 1396 EP 1400 PG 5 WC Optics SC Optics GA FH779 UT WOS:A1991FH77900016 PM 20700296 ER PT J AU FAHEY, RP MICHALITSIANOS, AG KAZANAS, D AF FAHEY, RP MICHALITSIANOS, AG KAZANAS, D TI C-IV LINE-PROFILE CORRELATIONS IN NGC-4151 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-4151); GALAXIES, NUCLEI; GALAXIES, SEYFERT; LINE PROFILES; ULTRAVIOLET, SPECTRA ID DETAILED OBSERVATIONS; EMISSION-LINE; IUE; VARIABILITY; SPECTRUM; NUCLEI AB The core of the strong UV resonance line C IV in the Seyfert 1 galaxy NGC 4151 is characterized by a double-peaked profile whose narrow emission features have relative intensities that vary as a function of the total C IV line strength. We present herein a set of novel correlations between the peak emission of each of these two components and the total luminosity of the C IV line. These correlations are distinctly different for the red and the blue peaks of the double-peaked C IV profile, implying that the physical parameters involved in their formation are quite different. The behavior of the red component appears more in accordance with the behavior of lines observed in other objects, with the peak intensity steadily increasing as the line brightens and broadens (though no specific correlations between these two quantities have, to our knowledge, been previously reported). The blue peak, however, appears much more directly and strongly related to C IV luminosity, and exhibits greater sensitivity to the C IV flux changes, becoming almost extinct when the active nucleus is in its low state. The very presence of these tight correlations, and the very simple, model-independent and direct method employed in obtaining them, imply the existence of specific (hitherto unknown) underlying physical processes. The distinctly different correlations exhibited by the blue and red peaks also suggests that distinct line-forming regions (in velocity space) produce the characteristic double-peaked profile of the C IV line in NGC 4151. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP FAHEY, RP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6841,GREENBELT,MD 20771, USA. NR 18 TC 5 Z9 5 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1991 VL 371 IS 1 BP 136 EP 141 DI 10.1086/169877 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE865 UT WOS:A1991FE86500014 ER PT J AU GALLAGHER, JS HUNTER, DA GILLETT, FC RICE, WL AF GALLAGHER, JS HUNTER, DA GILLETT, FC RICE, WL TI FAR-INFRARED PROPERTIES OF NGC-6822 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC-6822); GALAXIES, INTERSTELLAR MATTER; INFRARED, SOURCES; NEBULAE, H-II REGIONS ID DWARF IRREGULAR GALAXIES; H-II REGIONS; IRAS OBSERVATIONS; DARK NEBULAE; MAGELLANIC CLOUD; STAR FORMATION; PHOTOMETRY; IC-1613; SAMPLE AB NGC 6822 is one of the few noninteracting Magellanic irregular galaxies resolved in the far-infrared (FIR) by IRAS. Sources of FIR emission are studied through comparisons between the infrared intensity distributions in NGC 6822 and the distributions of young stellar complexes (including H II regions), older stars, and H I gas. We find that (1) The FIR emission at large radii from the center of NGC 6822 is due to Galactic cirrus. (2) There is a general correspondence between FIR emission, H II regions, and H I clouds, but there are local differences in the relative ratios of emission intensities. (3) The FIR appears to correlate mainly with the young stellar population although there is diffuse FIR emission as well. We propose a model for infrared emission from NGC 6822 in which the galaxy is relatively transparent due to its low metal abundance and hence reduced dust-to-gas ratio. FIR emission is strong only where there is a high UV radiation field energy density produced by OB stellar associations in combination with moderate optical depths due to the denser gas clouds associated with the young stars. The diffuse FIR emission results from low optical depth absorption of UV luminosity from more widely distributed A and B stars and from leakage of photons from OB star clusters. C1 LOWELL OBSERV,FLAGSTAFF,AZ 86001. NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91109. RP GALLAGHER, JS (reprint author), AURA INC,SUITE 701,1625 MASSACHUSETTS AVE NW,WASHINGTON,DC 20036, USA. OI Gallagher, John/0000-0001-8608-0408 NR 43 TC 27 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1991 VL 371 IS 1 BP 142 EP & DI 10.1086/169878 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE865 UT WOS:A1991FE86500015 ER PT J AU STAPELFELDT, KR BEICHMAN, CA HESTER, JJ SCOVILLE, NZ GAUTIER, TN AF STAPELFELDT, KR BEICHMAN, CA HESTER, JJ SCOVILLE, NZ GAUTIER, TN TI NEAR-INFRARED EMISSION-LINE IMAGES OF 3 HERBIG-HARO OBJECTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOURCES; NEBULAE, INDIVIDUAL (HH-7-11, HH-12, HH-34); SHOCK WAVES; STARS, PRE-MAIN-SEQUENCE ID VELOCITY MOLECULAR GAS; YOUNG STARS; LONG-SLIT; HH-34; JETS; SPECTROSCOPY; EXCITATION; HYDROGEN; OUTFLOWS; HH-7-11 AB HH 7-11, HH 12, and HH 34 have been observed with an infrared array camera using nine narrow-band filters. We report the first detection of the 1.64-mu-m line of [Fe II] in all three Herbig-Haro objects, including the HH 34 jet. Vibrational lines of H-2 were imaged in HH 7-11 and HH 12, but were not detected in HH 34. Brackett-gamma emission was not detected in any of the HH objects. The infrared results are compared with optical [S II] images. No new emission-line regions are revealed in the infrared data, suggesting that extinction plays little role in determining the optical appearance of these HH objects. The spatial distribution of [Fe II] emission is generally similar to the distribution of 6717 angstrom [S II] emission. The [Fe II]/[S II] ratio is very different in HH 12E, where the value is down by a factor of 7 relative to the rest of HH 12. At this location we suggest that the cooling and recombining flow behind the shock is disrupted before the [Fe II] emission zone can form. In HH 7-11 and HH 12, H-2 emission peaks are nearly always accompanied by [Fe II] and [S II] emission. In three locations (western HH 7; eastern HH 12C and HH 12D) ionized gas peaks occur without H-2 counterparts; these locations all occur 2"-5" upstream of H-2 emission. We identify these peaks without H-2 as shocked jet/wind material, displaced upstream from the H-2 emission at the flow terminus. We suggest that the geometry of a flow obstacle controls whether or not the standoff distance between the molecular and ionized gas shocks is large enough to be observable. No infrared continuum emission was detected from any of the HH objects, indicating that none contain embedded stars. An infrared reflection nebula has been detected to the north of the HH 34 exciting star. C1 CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91109. RP STAPELFELDT, KR (reprint author), CALTECH,PALOMAR OBSERV,MAIL CODE 10524,PASADENA,CA 91125, USA. RI Stapelfeldt, Karl/D-2721-2012 NR 38 TC 65 Z9 65 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1991 VL 371 IS 1 BP 226 EP & DI 10.1086/169884 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE865 UT WOS:A1991FE86500021 ER PT J AU AJELLO, JM JAMES, GK AF AJELLO, JM JAMES, GK TI CROSS-SECTIONS FOR PRODUCTION OF H(2P, 2S, 1S) BY ELECTRON COLLISIONAL DISSOCIATION OF H-2 SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; MOLECULAR PROCESSES; TRANSITION RATES ID EXTREME-ULTRAVIOLET EMISSION; IMPACT DISSOCIATION; MOLECULAR-HYDROGEN; RYDBERG SERIES; BAND SYSTEMS; LYMAN-ALPHA; EXCITATION; PREDISSOCIATION; DEUTERIUM; STATES AB We have measured the excitation function of H Ly-alpha produced by dissociative excitation of H-2 at energies 10-700 eV. The branches of the reaction have been separated using analytic models to fit the measured total excitation function. Strong threshold resonances by triplet states account for the sharp cross section rise at threshold, 14.7 eV. Above thresholds to 25 eV the e3-SIGMA-u+ state makes the largest contribution to the H Ly-alpha emission cross section by direct dissociation and predissociation of the d 3-PI-u state. The excitation function displays structure at approximately 30 eV which can be attributed to the production of fast (almost-equal-to 4 eV) H(2l) atoms from doubly excited states. Above 50 eV predissociation of the singlet states (D, D', B") by the B' state accounts for the largest contribution of the H Ly-alpha emission cross section. The yield of H(2p), H(2s), and H(1s) atoms contributing to the dissociation of H-2 into H(2l) and H(1s) atoms including cascade components was calculated from the measurements to be 33% +/- 5%, 23% +/- 4%, and 44% +/- 6%, respectively, at 100 eV. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RP AJELLO, JM (reprint author), CALTECH,JET PROP LAB,M-S 183-601,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 36 TC 37 Z9 37 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 APR 10 PY 1991 VL 371 IS 1 BP 422 EP 431 DI 10.1086/169904 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE865 UT WOS:A1991FE86500041 ER PT J AU BRUHWEILER, FC KONDO, Y GRADY, CA AF BRUHWEILER, FC KONDO, Y GRADY, CA TI MASS OUTFLOW IN THE NEARBY PROTO PLANETARY SYSTEM, BETA-PICTORIS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS; CIRCUMSTELLAR SHELLS; STARS; INDIVIDUAL (BETA-PICTORIS); STARS; MASS LOSS; ULTRAVIOLET; SPECTRA ID CIRCUMSTELLAR DISK; CA-II; STAR AB Previous spectral studies of circumstellar dust around the nearby, candidate proto-planetary system, beta-Pictoris, have detected only infalling gas. The lack of detectable mass outflow has been critical in the interpretation of the origin of the circumstellar gas and in our understanding of the evolutionary status of the beta-Pictoris system. We present International Ultraviolet Explorer (IUE) high-dispersion spectra which show, in addition to infall, the presence of mass outflow, with a maximum observed outflow velocity of -60 km s-1, and a corresponding instantaneous outflow rate of 1.1 x 10(-14) M. yr-1, or 1.1 x 10(-11) M(Jupiter) yr-1. This mass outflow rate and terminal velocity are comparable to the magnitudes of mass infall rates and terminal velocities observed from late 1986 through early 1988. The implications of these observations on our understanding of the mechanisms producing infall from the surrounding circumstellar disk are discussed, as are the implications for our understanding of the evolutionary status of the beta-Pic system. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BRUHWEILER, FC (reprint author), CATHOLIC UNIV AMER,DEPT PHYS,ASTROPHYS PROGRAM,WASHINGTON,DC 20064, USA. NR 24 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 APR 10 PY 1991 VL 371 IS 1 BP L27 EP L31 DI 10.1086/185994 PN 2 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE867 UT WOS:A1991FE86700007 ER PT J AU LEIBUNDGUT, B KIRSHNER, RP FILIPPENKO, AV SHIELDS, JC FOLTZ, CB PHILLIPS, MM SONNEBORN, G AF LEIBUNDGUT, B KIRSHNER, RP FILIPPENKO, AV SHIELDS, JC FOLTZ, CB PHILLIPS, MM SONNEBORN, G TI PREMAXIMUM OBSERVATIONS OF THE TYPE-IA SN-1990N SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES; INDIVIDUAL (NGC-4639); STARS; INDIVIDUAL (SN-1990N); STARS; SUPERNOVAE; ULTRAVIOLET; SPECTRA ID WHITE-DWARF MODELS; VIRGO CLUSTER; SUPERNOVAE; GALAXIES; CATALOG; SPECTRA; VELOCITIES; DISTANCES AB Spectroscopic and photometric observations of SN 1990N were obtained at ultraviolet and optical wavelengths, beginning 14 days before maximum light. The early observations reveal important differences from spectra of SN Ia's around maximum light. Photometry and spectroscopy obtained after maximum show that SN 1990N is a typical SN Ia and that most of the observed differences are due to the early epoch of the observations. The most significant characteristics are (1) the high velocities of Ca and Si up to 22,000 km s-1, (2) the presence of Co and Fe 2 weeks before maximum, and (3) the more rapid increase in the UV flux compared to the optical. The most popular models for white dwarf deflagration that have provided the standard interpretation for SN Ia's at maximum light do not reproduce the high velocities of Ca II and Si II lines observed in SN 1990N. C1 UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. MULTIPLE MIRROR TELESCOPE OBSERV,TUCSON,AZ 85721. CERRO TOLOLO INTERAMER OBSERV,LA SERENA,CHILE. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP LEIBUNDGUT, B (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. NR 37 TC 121 Z9 121 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1991 VL 371 IS 1 BP L23 EP L26 DI 10.1086/185993 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE867 UT WOS:A1991FE86700006 ER PT J AU SMOOT, GF BENNETT, CL KOGUT, A AYMON, J BACKUS, C DEAMICI, G GALUK, K JACKSON, PD KEEGSTRA, P ROKKE, L TENORIO, L TORRES, S GULKIS, S HAUSER, MG JANSSEN, MA MATHER, JC WEISS, R WILKINSON, DT WRIGHT, EL BOGGESS, NW CHENG, ES KELSALL, T LUBIN, P MEYER, S MOSELEY, SH MURDOCK, TL SHAFER, RA SILVERBERG, RF AF SMOOT, GF BENNETT, CL KOGUT, A AYMON, J BACKUS, C DEAMICI, G GALUK, K JACKSON, PD KEEGSTRA, P ROKKE, L TENORIO, L TORRES, S GULKIS, S HAUSER, MG JANSSEN, MA MATHER, JC WEISS, R WILKINSON, DT WRIGHT, EL BOGGESS, NW CHENG, ES KELSALL, T LUBIN, P MEYER, S MOSELEY, SH MURDOCK, TL SHAFER, RA SILVERBERG, RF TI PRELIMINARY-RESULTS FROM THE COBE DIFFERENTIAL MICROWAVE RADIOMETERS - LARGE ANGULAR SCALE ISOTROPY OF THE COSMIC MICROWAVE BACKGROUND SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC BACKGROUND RADIATION; COSMOLOGY; EARLY UNIVERSE ID RADIATION; ROTATION; ANISOTROPY; UNIVERSE AB The COBE Differential Microwave Radiometers (DMR) instrument has produced preliminary full sky microwave maps at 31.5, 53, and 90 GHz with two independent channels at each frequency. At millimeter wavelengths, the cosmic microwave background (CMB) dominates the sky brightness with an intensity more than a thousand times the foreground Galactic emission. Emission from our Galaxy is seen unambiguously at all three frequencies. The dipole anisotropy, attributed to the motion of our solar system with respect to the CMB reference frame, shows strongly in all six sky maps and is consistent with a Doppler-shifted thermal spectrum. The best fitted dipole has amplitude 3.3 +/- 0.2 mK in the direction (alpha, delta) = (11.2h +/- O.2h,-7-degrees +/- 2-degrees) (J2000) or (l, b) = (265-degrees +/- 2-degrees, 48-degrees +/- 2-degrees). There is no clear evidence in the maps for any other large angular scale features. We place a limit of DELTA-T/T0 < 3 x 10(-5) (T0 = 2.735 K) for the rms quadrupole amplitude; for monochromatic fluctuations DELTA-T/T0 < 4 x 10(-5); and for Gaussian fluctuations DELTA-T/T0 < 4 x 10(-5). All limits are given at the 95% confidence level and reflect currently estimated limits on systematic effects. These measurements place the most severe constraints to date on many potential physical processes in the early universe, such as anisotropic expansion of the universe, very long wavelength gravitational waves, cosmic strings, and large-scale primordial fluctuations. C1 ST SYST INC,LANHAM,MD 20706. UNIV CALIF SANTA BARBARA,DEPT PHYS,GOLETA,CA 93106. GEN RES CORP,DANVERS,MA 01923. UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,NATL RES COUNCIL,GREENBELT,MD 20771. CALTECH,JET PROP LAB,PASADENA,CA 91109. MIT,DEPT PHYS,CAMBRIDGE,MA 02139. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. RP SMOOT, GF (reprint author), UNIV CALIF BERKELEY LAWRENCE BERKELEY LAB,MS 50-232,BERKELEY,CA 94720, USA. RI Moseley, Harvey/D-5069-2012; Kogut, Alan/D-6293-2012; Rokke, Laurie/I-5642-2015 OI Rokke, Laurie/0000-0002-5696-7240 NR 25 TC 171 Z9 172 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 APR 10 PY 1991 VL 371 IS 1 BP L1 EP & DI 10.1086/185988 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE867 UT WOS:A1991FE86700001 ER PT J AU CHAO, BF AU, AY AF CHAO, BF AU, AY TI TEMPORAL VARIATION OF THE EARTHS LOW-DEGREE ZONAL GRAVITATIONAL-FIELD CAUSED BY ATMOSPHERIC MASS REDISTRIBUTION - 1980-1988 SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS LA English DT Article ID ANGULAR-MOMENTUM; LAGEOS; LENGTH; ROTATION; ACCELERATION; STARLETTE; VISCOSITY; MANTLE; WOBBLE AB Temporal variations in the low-degree zonal harmonics of the Earth's gravitational field have recently been observed by satellite laser ranging. A host of geophysical processes contribute to these variations. The present paper studies quantitatively a prime contributor, atmospheric mass redistribution, using global surface pressure data from the European Centre for Medium Range Weather Forecasts for the period of 1980-1988. Seasonal variations are focused upon: We compute the annual and semiannual amplitudes and phases of the zonal J(l) coefficient with degree l = 2-6 with and without the oceanic inverted-barometer (IB) effect and obtain the predicted effects on the orbit nodal residuals delta-OMEGA of Lageos and Starlette. These predicted delta-OMEGA are then compared with the observed delta-OMEGA. It is found that the atmospheric influence, combined with the hydrological influence (from Chao and O'Connor, 1988), agree well with the Lageos observation for the annual term. The corresponding match appears poorer for Starlette. The comparisons for the semiannual term, however, show little agreement. The discrepancies can be attributed primarily to the uncertainty arising from the IB assumption, the systematic errors in the hydrological estimates and in the observations, as well as other geophysical processes that influence global mass distribution, particularly those in the oceans. Interannual and decadal variations, with their impact on the observations of "secular" changes are also discussed. C1 ST SYST CORP,LANHAM,MD 20706. RP CHAO, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,CODE 921,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 33 TC 39 Z9 43 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-SOLID PD APR 10 PY 1991 VL 96 IS B4 BP 6569 EP 6575 DI 10.1029/91JB00042 PG 7 WC Geosciences, Multidisciplinary SC Geology GA FG773 UT WOS:A1991FG77300046 ER PT J AU CHAO, BF AU, AY AF CHAO, BF AU, AY TI ATMOSPHERIC EXCITATION OF THE EARTHS ANNUAL WOBBLE - 1980-1988 SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS LA English DT Article ID ANGULAR-MOMENTUM; POLAR MOTION; METEOROLOGICAL EXCITATION; EL-NINO; LENGTH; ROTATION; FLUCTUATIONS; OCEANS; WINDS AB Global meterological analyses from the European Centre for Medium Range Weather Forecasts are employed to compute the atmospheric excitation PSI of the polar motion for the 9-year period of 1980-1988. Both the matter component PSI(matter) and the motion component PSI(motion) are computed, the former with and without the oceanic inverted barometer (IB) effect. It is found that PSI(motion) contributes significantly to the total excitation PSI overall and nonnegligibly to the annual signal in PSI, or the annual wobble excitation, in particular. Our results for the annual wobble excitation, in terms of the prograde component PSI+ and the retrograde component PSI- for January 1, are PSI+ = (16.8 milliarc seconds (mas), -93-degrees) and PSI- = (15.6 mas, -98-degrees) with IB, and PSI+ = (17.3 mas, -101-degrees) and PSI- = (28.1 mas, -112-degrees) without IB. These results are within the (rather large) range of previous estimates. The IB effect has a small impact on PSI+, whereas its impact on PSI- is considerable. The (better determined) prograde components PSI+ are then compared with that observed from the Lageos satellite laser ranging data: (17.3 mas, -61-degrees). Although the amplitudes are nearly equal, large phase discrepancies exist between the atmospheric and this observed value. The resolution of this discrepancy awaits a better knowledge of the seasonal angular momentum budget of the Earth's surface fluid elements. C1 ST SYST CORP,LANHAM,MD 20706. RP CHAO, BF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,CODE 921,GREENBELT,MD 20771, USA. RI Chao, Benjamin Fong/N-6156-2013 NR 33 TC 43 Z9 49 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-SOLID PD APR 10 PY 1991 VL 96 IS B4 BP 6577 EP 6582 DI 10.1029/91JB00041 PG 6 WC Geosciences, Multidisciplinary SC Geology GA FG773 UT WOS:A1991FG77300047 ER PT J AU RENDELL, AP LEE, TJ KOMORNICKI, A AF RENDELL, AP LEE, TJ KOMORNICKI, A TI A PARALLEL VECTORIZED IMPLEMENTATION OF TRIPLE EXCITATIONS IN CCSD(T) - APPLICATION TO THE BINDING-ENERGIES OF THE ALH3, ALH2F, ALHF2 AND ALF3 DIMERS SO CHEMICAL PHYSICS LETTERS LA English DT Article ID BODY PERTURBATION-THEORY; MOLECULAR ELECTRONIC-STRUCTURE; GAUSSIAN-BASIS SETS; 2ND-ROW ATOMS; ROW ATOMS; MODEL; CONTRACTION; SPECTRA; STATE AB An efficient method for evaluating various non-iterative estimates of connected triple excitations in coupled-cluster theory is outlined and related to a similar expression occurring in Moller-Plesset perturbation theory. The method is highly vectorized and capable of utilizing multiple processors on a shared-memory machine, leading to computational rates in excess of one billion floating-point operations per second on four processors of a CRAY Y-MP. Using the new procedure, the binding energies of the D2h diborane-type dimers of AlH3, AlH2F, AlHF2 and AlF3 have been determined to be 32, 40, 20 and 47 kcal/mol, respectively. For Al2F6, the correlation procedure includes 232 molecular orbitals and over 1.5 x 10(6) single and double coupled-cluster amplitudes, effectively accounting for over 2 x 10(9) connected triple excitations. C1 POLYATOM RES INST, MT VIEW, CA 94043 USA. RP RENDELL, AP (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Rendell, Alistair/A-4883-2008; Lee, Timothy/K-2838-2012 OI Rendell, Alistair/0000-0002-9445-0146; NR 35 TC 64 Z9 64 U1 0 U2 6 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD APR 5 PY 1991 VL 178 IS 5-6 BP 462 EP 470 DI 10.1016/0009-2614(91)87003-T PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FG959 UT WOS:A1991FG95900003 ER PT J AU COLUSSI, AJ SANDER, SP FRIEDL, RR AF COLUSSI, AJ SANDER, SP FRIEDL, RR TI THERMODYNAMICS OF ACETYLENE VANDERWAALS DIMERIZATION SO CHEMICAL PHYSICS LETTERS LA English DT Article ID INFRARED-SPECTROSCOPY; STATIONARY-POINTS; PHOTOCHEMISTRY; CLUSTERS; ATMOSPHERE; AEROSOLS; (C2H2)3 AB Integrated band intensities of the 620 cm-1 absorption in (C2H2)2 have been measured by FTIR spectroscopy at constant acetylene pressure between 198 and 273 K. These data, in conjunction with ab initio results for (C2H2)2, have been used for the statistical evaluation of the equilibrium constant K(p)(T) for acetylene cluster dimerization. Present results are used to clarify the role of molecular clusters in chemical systems at or near equilibrium, in particular in Titan's stratosphere. RP COLUSSI, AJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI Colussi, Agustin/C-6520-2008 NR 33 TC 16 Z9 16 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD APR 5 PY 1991 VL 178 IS 5-6 BP 497 EP 503 DI 10.1016/0009-2614(91)87009-Z PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FG959 UT WOS:A1991FG95900009 ER PT J AU BALL, KS SIROVICH, L KEEFE, LR AF BALL, KS SIROVICH, L KEEFE, LR TI DYNAMIC EIGENFUNCTION DECOMPOSITION OF TURBULENT CHANNEL FLOW SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE TURBULENCE; CHANNEL FLOW; KARHUNEN-LOEVE EXPANSION; EIGENFUNCTIONS; ORTHOGONAL DECOMPOSITION ID COHERENT STRUCTURES; MODEL AB The results of an analysis of low-Reynolds-number turbulent channel flow based on the Karhunen-Loeve (K-L) expansion are presented. The turbulent flow field is generated by a direct numerical simulation of the Navier-Stokes equations at a Reynolds number Re-tau = 80 (based on the wall shear velocity and channel half-width). The K-L procedure is then applied to determine the eigenvalues and eigenfunctions for this flow. The random coefficients of the K-L expansion are subsequently found by projecting the numerical flow field onto these eigenfunctions. The resulting expansion captures 90% of the turbulent energy with significantly fewer modes than the original trigonometric expansion. The eigenfunctions, which appear either as rolls or shearing motions, possess viscous boundary layers at the walls and are much richer in harmonics than the original basis functions. Chaotic temporal behaviour is observed in all modes and increases for higher-order eigenfunctions. The structure and dynamical behaviour of the eigenmodes are discussed as well as their use in the representation of turbulent flow. C1 BROWN UNIV,CTR FLUID MECH TURBULENCE & COMPUTAT,DIV APPL MATH,PROVIDENCE,RI 02912. NASA,AMES RES CTR,CTR TURBULENCE RES,MOFFETT FIELD,CA 94035. RP BALL, KS (reprint author), UNIV TEXAS,DEPT MECH ENGN,AUSTIN,TX 78712, USA. NR 19 TC 79 Z9 81 U1 0 U2 2 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD APR 5 PY 1991 VL 12 IS 6 BP 585 EP 604 DI 10.1002/fld.1650120606 PG 20 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA FG936 UT WOS:A1991FG93600005 ER PT J AU MARDER, SR BERATAN, DN CHENG, LT AF MARDER, SR BERATAN, DN CHENG, LT TI APPROACHES FOR OPTIMIZING THE 1ST ELECTRONIC HYPERPOLARIZABILITY OF CONJUGATED ORGANIC-MOLECULES SO SCIENCE LA English DT Article ID 2ND HARMONIC-GENERATION; OPTICAL SUSCEPTIBILITIES; SYSTEMS AB A two-state, four-orbital, independent electron analysis of the first optical molecular hyperpolarizability, beta, leads to the prediction that (beta) maximizes at a combination of donor and acceptor strengths for a given conjugated bridge. Molecular design strategies that focus on the energetic manipulations of the bridge states are proposed for the optimization of beta. The limitations of molecular classes based on common bridge structures are highlighted and more promising candidates are described. Experimental results supporting the validity of this approach are presented. C1 DUPONT CO,WILMINGTON,DE 19880. CALTECH,BECKMAN INST,PASADENA,CA 91125. RP MARDER, SR (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. RI Beratan, David/C-5098-2011 NR 32 TC 645 Z9 650 U1 6 U2 53 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD APR 5 PY 1991 VL 252 IS 5002 BP 103 EP 106 DI 10.1126/science.252.5002.103 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FE952 UT WOS:A1991FE95200042 PM 17739081 ER PT J AU KAZANAS, D AF KAZANAS, D TI COSMIC-RAYS AND PARTICLE PHYSICS - GAISSER,TK SO NATURE LA English DT Book Review RP KAZANAS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 1 TC 0 Z9 0 U1 0 U2 1 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD APR 4 PY 1991 VL 350 IS 6317 BP 390 EP 390 DI 10.1038/350390a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FF042 UT WOS:A1991FF04200038 ER PT J AU MARAN, SP MICHALITSIANOS, AG OLIVERSEN, RJ SONNEBORN, G AF MARAN, SP MICHALITSIANOS, AG OLIVERSEN, RJ SONNEBORN, G TI SPECTRAL TRANSFORMATION OF THE UNUSUAL VARIABLE-STAR MWC560 TO RESEMBLE A NOVA SO NATURE LA English DT Article AB MWC560 is an emission-line star catalogued 1 in 1943 and later described 2 as an 'extraordinary symbiotic-like variable'. It was recently found 3 to be undergoing a photometric and spectroscopic outburst. A dramatic change has occurred in the ultraviolet spectrum of MWC560, so that it now closely resembles the spectrum of a nova shortly after outburst. This event, detected by the International Ultraviolet Explorer satellite, may signal a major mass-ejection episode such as presumably occurred in past centuries in the symbiotic star R Aquarii to produce the well-known bipolar nebula, and it may herald the emergence of a standard symbiotic-star emission-line spectrum in MWC560, corresponding to a change in evolutionary state. RP MARAN, SP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 13 TC 12 Z9 12 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD APR 4 PY 1991 VL 350 IS 6317 BP 404 EP 406 DI 10.1038/350404a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FF042 UT WOS:A1991FF04200042 ER PT J AU CASNER, SM AF CASNER, SM TI A TASK-ANALYTIC APPROACH TO THE AUTOMATED DESIGN OF GRAPHIC PRESENTATIONS SO ACM TRANSACTIONS ON GRAPHICS LA English DT Article DE ALGORITHMS; DESIGN; HUMAN FACTORS; THEORY; AUTOMATED DESIGN; GRAPHIC DESIGN; GRAPHIC USER INTERFACE; TASK ANALYSIS; VISUAL LANGUAGES ID GUIDELINES AB BOZ is an automated graphic design and presentation tool that designs graphics based on an analysis of the task for which a graphic is intended to support. When designing a graphic, BOZ aims to optimize two ways in which graphics help expedite human performance of information-processing tasks: (1) allowing users to substitute simple perceptual inferences in place of more demanding logical inferences, and (2) streamlining users' search for needed information. BOZ analyzes a logical description of a task to be performed by a human user and designs a provably equivalent perceptual task by substituting perceptual inferences in place of logical inferences in the task description. BOZ then designs and renders an accompanying graphic that encodes and structures data such that performance of each perceptual inference is supported and visual search is minimized. BOZ produces a graphic along with a perceptual procedure describing how to use the graphic to complete the task. A key feature of BOZ's approach is that it is able to design different presentations of the same information customized to the requirements of different tasks. BOZ is used to design graphic presentations of airline schedule information to support five different airline reservation tasks. Reaction time studies done with real users for one task and graphic show that the BOZ-designed graphic significantly reduces user's performance time to the task. Regression analyses link the observed efficiency savings to BOZ's two key design principles: perceptual inference substitutions and pruning of visual search. C1 UNIV PITTSBURGH,INTELLIGENT SYST PROGRAM,PITTSBURGH,PA 15260. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 36 TC 101 Z9 101 U1 0 U2 7 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0730-0301 J9 ACM T GRAPHIC JI ACM Trans. Graph. PD APR PY 1991 VL 10 IS 2 BP 111 EP 151 DI 10.1145/108360.108361 PG 41 WC Computer Science, Software Engineering SC Computer Science GA FM837 UT WOS:A1991FM83700001 ER PT J AU VARSI, G AF VARSI, G TI ADVANCES IN SPACE ROBOTICS SO ACTA ASTRONAUTICA LA English DT Article; Proceedings Paper CT 40TH CONGRESS OF THE INTERNATIONAL ASTRONAUTICAL FEDERATION CY OCT 07-13, 1989 CL MALAGA, SPAIN SP INT ASTRONAUT FEDERAT AB As we enter the last decade of the twentieth century we see two principal foci for activities and interest in space in the twenty-first century: exploration of the surface of bodies of the solar system and exploitation of space in near Earth orbit for the benefit of mankind. There are two enabling tools for this enterprise: improved, less expensive transportation to and from orbit and remote control of space operations. This contribution addresses the latter by identifying the key technical challenge: the management of contact forces and the principal performance parameters: the degree of structure of the task and work-site and the communication delay between control station and remote site. Three principal classes of devices for remote operation are identified: anthropomorphic exoskeletons, computer aided teleoperators and supervised telerobots. Their fields of application are described and areas in which progress has reached the level of system or subsystem laboratory demonstrations are indicated. Key test results, indicating performance at a level useful for design tradeoffs, are reported. RP VARSI, G (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD APR PY 1991 VL 25 IS 4 BP 199 EP 207 DI 10.1016/0094-5765(91)90072-D PG 9 WC Engineering, Aerospace SC Engineering GA FY828 UT WOS:A1991FY82800003 ER PT J AU LANDIS, GA AF LANDIS, GA TI SATELLITE ECLIPSE POWER BY LASER ILLUMINATION SO ACTA ASTRONAUTICA LA English DT Article AB A method is proposed to eliminate the energy storage system required to power a satellite in geosynchronous orbit during eclipse. An array of high-power CW lasers is situated at one or more ground locations in line of sight of the satellite, preferably on mountaintops. The lasers are provided with a tracking system, and lenses or mirrors of sufficient size to reduce the beam spread due to diffraction. As the satellite enters eclipse, the laser arrays illuminate the solar arrays on the satellite to a level sufficient to provide operating power. RP LANDIS, GA (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,302-1,CLEVELAND,OH 44135, USA. NR 0 TC 7 Z9 8 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD APR PY 1991 VL 25 IS 4 BP 229 EP 233 DI 10.1016/0094-5765(91)90075-G PG 5 WC Engineering, Aerospace SC Engineering GA FY828 UT WOS:A1991FY82800006 ER PT J AU WHITAKER, AF AF WHITAKER, AF TI COATINGS COULD PROTECT COMPOSITES FROM HOSTILE SPACE ENVIRONMENT SO ADVANCED MATERIALS & PROCESSES LA English DT Article RP WHITAKER, AF (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,MAT & PROC LAB,CODE EH11,HUNTSVILLE,AL 35812, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU ASM INTERNATIONAL PI MATERIALS PARK PA SUBSCRIPTIONS SPECIALIST CUSTOMER SERVICE, MATERIALS PARK, OH 44073-0002 SN 0026-0665 J9 ADV MATER PROCESS JI Adv. Mater. Process. PD APR PY 1991 VL 139 IS 4 BP 30 EP 32 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA FE615 UT WOS:A1991FE61500004 ER PT J AU DICKINSON, RE HENDERSON-SELLERS, A ROSENZWEIG, C SELLERS, PJ AF DICKINSON, RE HENDERSON-SELLERS, A ROSENZWEIG, C SELLERS, PJ TI EVAPOTRANSPIRATION MODELS WITH CANOPY RESISTANCE FOR USE IN CLIMATE MODELS - A REVIEW SO AGRICULTURAL AND FOREST METEOROLOGY LA English DT Article ID SENSITIVITY; LAYER; CO2 AB The most advanced climate models are now incorporating effects of vegetation into their surface energy and hydrological balance formulations. These efforts are reviewed here with emphasis on the canopy resistance component through development of a simple generic canopy model that includes the relatively well-established processes common to several canopy submodels. We also review where the land surface treatments diverge, in particular in their consideration of water stress, partial vegetation, within-canopy resistances and computational algorithms for the determination of canopy temperature. The inclusion of canopy submodels in climate models may be of questionable utility without improvements in some aspects of atmospheric simulations, such as the modeled distributions of precipitation and incident surface radiation. Improved treatments of the heterogeneous nature of precipitation and land surface properties are also needed. C1 MACQUARIE UNIV, SCH EARTH SCI, SYDNEY, NSW 2109, AUSTRALIA. NASA, GODDARD INST SPACE STUDIES, NEW YORK, NY 10025 USA. COLUMBIA UNIV, NEW YORK, NY 10027 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP DICKINSON, RE (reprint author), NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. RI Henderson-Sellers, Ann/H-5323-2011 NR 20 TC 95 Z9 110 U1 3 U2 16 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-1923 J9 AGR FOREST METEOROL JI Agric. For. Meteorol. PD APR PY 1991 VL 54 IS 2-4 BP 373 EP 388 DI 10.1016/0168-1923(91)90014-H PG 16 WC Agronomy; Forestry; Meteorology & Atmospheric Sciences SC Agriculture; Forestry; Meteorology & Atmospheric Sciences GA FP090 UT WOS:A1991FP09000014 ER PT J AU DEMUREN, AO AF DEMUREN, AO TI CALCULATION OF TURBULENCE-DRIVEN SECONDARY MOTION IN DUCTS WITH ARBITRARY CROSS-SECTION SO AIAA JOURNAL LA English DT Article ID REYNOLDS-STRESS; FLOW AB Calculation methods for turbulent duct flows are generalized for ducts with arbitrary cross sections. The irregular physical geometry is transformed into a regular one in computational space, and the flow equations are solved with a finite-volume numerical procedure. The turbulent stresses are calculated with an algebraic stress model derived by simplifying model transport equations for the individual Reynolds stresses. Two variants of such a model are considered in the present study. These procedures enable the prediction of both the turbulence-driven secondary flow and the anisotropy of the Reynolds stresses, in contrast to some of the earlier calculation methods. The importance of the secondary Reynolds shear stress is stressed, but there are no reliable experimental data for this component. Model predictions are compared to experimental data for developed flow in a triangular duct and a rod-bundle geometry. The correct trends are predicted, and the quantitative agreement is mostly fair. The simpler variant of the algebraic stress model procured better agreement with measured data. C1 NASA, LEWIS RES CTR, INST COMPUTAT MECH PROP, CLEVELAND, OH 44135 USA. NR 17 TC 14 Z9 14 U1 1 U2 2 PU AMER INST AERONAUTICS ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0001-1452 EI 1533-385X J9 AIAA J JI AIAA J. PD APR PY 1991 VL 29 IS 4 BP 531 EP 537 DI 10.2514/3.10616 PG 7 WC Engineering, Aerospace SC Engineering GA FJ316 UT WOS:A1991FJ31600007 ER PT J AU KIM, SW AF KIM, SW TI CALCULATION OF DIVERGENT CHANNEL FLOWS WITH A MULTIPLE-TIME-SCALE TURBULENCE MODEL SO AIAA JOURNAL LA English DT Article ID LAYER AB Numerical calculations of turbulent reattaching shear layers in a divergent channel are presented. The turbulence is described by a multiple-time-scale turbulence model. The turbulent flow equations are solved by a control-volume-based finite-difference method. The computational results are compared with those obtained using k-epsilon turbulence models and algebraic Reynolds stress turbulence models. It is shown that the multiple-time-scale turbulence model yields significantly improved computational results compared with the other turbulence models in the region where the turbulence is in a strongly nonequilibrium state. RP KIM, SW (reprint author), NASA,LEWIS RES CTR,INST COMPUTAT MECH PROP,CLEVELAND,OH 44135, USA. NR 25 TC 14 Z9 15 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 APR PY 1991 VL 29 IS 4 BP 547 EP 554 DI 10.2514/3.10618 PG 8 WC Engineering, Aerospace SC Engineering GA FJ316 UT WOS:A1991FJ31600009 ER PT J AU MAHAJAN, AJ DOWELL, EH BLISS, DB AF MAHAJAN, AJ DOWELL, EH BLISS, DB TI ROLE OF ARTIFICIAL VISCOSITY IN EULER AND NAVIER-STOKES SOLVERS SO AIAA JOURNAL LA English DT Article ID DISSIPATION MODELS; EQUATIONS AB A method is proposed to determine directly the amount of artificial viscosity needed for stability using an eigenvalue analysis for a finite difference representation of the Navier-Stokes equations. The stability and growth of small perturbations about a steady flow over airfoils are analyzed for various amounts of artificial viscosity. The eigenvalues were determined for a small time-dependent perturbation about a steady inviscid flow over a NACA 0012 airfoil at a Mach number of 0.8 and angle of attack of 0 deg. The method has been applied to inviscid flows here, but as discussed is also applicable to viscous flows. The movement of the eigenvalue constellation with respect to the amount of artificial viscosity is studied. The stability boundaries as a function of the amount of artificial viscosity from both the eigenvalue analysis and the time-marching scheme are also presented. The eigenvalue procedure not only allows for determining the effect of varying amounts of artificial viscosity, but also for the effects of different forms of artificial viscosity. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. DUKE UNIV,DEPT MECH ENGN & MAT SCI,DURHAM,NC 27706. DUKE UNIV,SCH ENGN,DURHAM,NC 27706. NR 18 TC 7 Z9 7 U1 1 U2 4 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 APR PY 1991 VL 29 IS 4 BP 555 EP 559 DI 10.2514/3.10619 PG 5 WC Engineering, Aerospace SC Engineering GA FJ316 UT WOS:A1991FJ31600010 ER PT J AU DEGANI, D AF DEGANI, D TI EFFECT OF GEOMETRICAL DISTURBANCE ON VORTEX ASYMMETRY SO AIAA JOURNAL LA English DT Article ID CIRCULAR-CYLINDER; FLOW; INSTABILITY; SEPARATION; ABSOLUTE AB The phenomena of the flow about a slender body of revolution placed at incidence to an oncoming stream were numerically investigated for angles of attack of 20 and 40 deg and a Reynolds number of 2 x 10(5) based on maximum body diameter. At angle of attack of 20 deg, the flow was steady and symmetric, and the presence of a perturbation, which was placed near the tip of the body, made only a small change. At angle of attack of 40 deg, the flow was found to be steady (except for a small-amplitude, high-frequency unsteadiness of the shear layer), but became highly asymmetric when a space-fixed, time-invariant disturbance was added near the tip. The level of the asymmetry was dependent on the size and location of the disturbance. When the disturbance was removed, the flowfield relaxed to its original symmetric shape. On the basis of this observation, experimental data, and other theoretical indicators, it is suggested that the origin of the asymmetry is a convective-type instability of the originally symmetric flow. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 36 TC 27 Z9 27 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 APR PY 1991 VL 29 IS 4 BP 560 EP 566 DI 10.2514/3.59929 PG 7 WC Engineering, Aerospace SC Engineering GA FJ316 UT WOS:A1991FJ31600011 ER PT J AU ROGERS, SE KWAK, D KIRIS, C AF ROGERS, SE KWAK, D KIRIS, C TI STEADY AND UNSTEADY SOLUTIONS OF THE INCOMPRESSIBLE NAVIER-STOKES EQUATIONS SO AIAA JOURNAL LA English DT Article ID CIRCULAR-CYLINDER; FLOW; PSEUDOCOMPRESSIBILITY; WAKE AB An algorithm for the solution of the incompressible Navier-Stokes equations in three-dimensional generalized curvillinear coordinates is presented. The algorithm can be used to compute both steady-state and time-dependent flow problems. The algorithm is based on the method of artificial compressibility and uses a third-order flux-difference splitting technique for the convective terms and the second-order central difference for the viscous terms. Time accuracy is obtained in the numerical solutions by subiterating the equations in pseudotime for each physical time step. The equations are solved with a line-relaxation scheme that allows the use of very large pseudotime steps leading to fast convergence for steady-state problems as well as for the subiterations of time-dependent problems. The steady-state solution of flow through a square duct with a 90-deg bend is computed, and the results are compared with experimental data. Good agreement is observed. Computations of unsteady flow over a circular cylinder are presented and compared to other experimental and computational results. Finally, the flow through an artificial heart configuration with moving boundaries is calculated and presented. C1 STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. RP ROGERS, SE (reprint author), NASA,AMES RES CTR,DEPT AERONAUT & ASTRONAUT,MOFFETT FIELD,CA 94035, USA. NR 27 TC 218 Z9 239 U1 0 U2 11 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 APR PY 1991 VL 29 IS 4 BP 603 EP 610 DI 10.2514/3.10627 PG 8 WC Engineering, Aerospace SC Engineering GA FJ316 UT WOS:A1991FJ31600018 ER PT J AU KAPANIA, RK DOENCHBERGEN, F BARTHELEMY, JFM AF KAPANIA, RK DOENCHBERGEN, F BARTHELEMY, JFM TI SHAPE SENSITIVITY ANALYSIS OF FLUTTER RESPONSE OF A LAMINATED WING SO AIAA JOURNAL LA English DT Note AB An approach is presented for calculating the shape sensitivity of a wing flutter response with respect to changes in geometric shape. Three methods are used to calculate the sensitivity of the flutter eigenvalue. The first method is purely a finite-difference calculation of the eigenvalue derivative directly from the solution of the flutter problem for two different values of the shape parameters. The second method uses an analytic expression for the eigenvalue sensitivities of a general complex matrix, where the derivatives of the aerodynamic, mass, and stiffness matrices are computed using a finite-difference approximation. The third method also uses the same analytic expression for the eigenvalue sensitivities, but the sensitivity of the aerodynamic matrix is computed analytically. In each method, a modified strip aerodynamic theory and an equivalent plate structural analysis technique (to represent the wing structure) are used to predict the dynamic aeroelastic behavior of the wing. Results from applying all three methods to a sample problem are found to be in good agreement with each other. C1 NASA,LANGLEY RES CTR,INTERDISCIPLINARY RES OFF,HAMPTON,VA 23665. RP KAPANIA, RK (reprint author), VIRGINIA POLYTECH INST & STATE UNIV,DEPT AEROSP & OCEAN ENGN,BLACKSBURG,VA 24061, USA. NR 7 TC 5 Z9 5 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD APR PY 1991 VL 29 IS 4 BP 611 EP 612 DI 10.2514/3.59930 PG 2 WC Engineering, Aerospace SC Engineering GA FJ316 UT WOS:A1991FJ31600019 ER PT J AU CHEN, JC FANSON, JL AF CHEN, JC FANSON, JL TI SYSTEM-IDENTIFICATION TEST USING ACTIVE MEMBERS SO AIAA JOURNAL LA English DT Article ID LARGE SPACE STRUCTURES AB A modal test using active members as the excitation source has been performed on a test bed truss structure representative of a portion of a large space system. Using the step sine testing technique, the frequency response functions are obtained and the modal parameters are extracted by the curve-fitting method. A total of 10 global modes and 3 local modes are obtained. The results are compared with those obtained by the conventional external excitation test. C1 CALTECH,JET PROP LAB,ADV TECHNOL SECT,PASADENA,CA 91109. RP CHEN, JC (reprint author), HONG KONG UNIV SCI & TECHNOL,MECH ENGN,KOWLOON,HONG KONG. NR 14 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD APR PY 1991 VL 29 IS 4 BP 633 EP 640 DI 10.2514/3.10632 PG 8 WC Engineering, Aerospace SC Engineering GA FJ316 UT WOS:A1991FJ31600023 ER PT J AU PHILLIPS, TN KARAGEORGHIS, A AF PHILLIPS, TN KARAGEORGHIS, A TI A CONFORMING SPECTRAL COLLOCATION STRATEGY FOR STOKES-FLOW THROUGH A CHANNEL CONTRACTION SO APPLIED NUMERICAL MATHEMATICS LA English DT Article ID LAMINAR-FLOW; GEOMETRIES; DOMAINS AB A spectral collocation method is described for solving the stream function formulation of the Stokes problem in a contraction geometry. The flow region is decomposed into a number of conformal rectangular subregions. A collocation strategy is devised which ensures that the stream function and its normal derivative are continuous across subregion interfaces. An efficient solution procedure based on the capacitance matrix technique is described for solving the spectral collocation equations. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. SO METHODIST UNIV,DEPT MATH,DALLAS,TX 75275. RP PHILLIPS, TN (reprint author), UNIV COLL WALES,DEPT MATH,ABERYSTWYTH SY23 3BZ,WALES. OI Phillips, Timothy/0000-0001-6455-1205 NR 17 TC 1 Z9 1 U1 0 U2 2 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 APR PY 1991 VL 7 IS 4 BP 329 EP 345 DI 10.1016/0168-9274(91)90068-B PG 17 WC Mathematics, Applied SC Mathematics GA FM027 UT WOS:A1991FM02700004 ER PT J AU WILSON, CD SCOVILLE, N RICE, W AF WILSON, CD SCOVILLE, N RICE, W TI HIGH-MASS STAR-FORMATION RATES IN M33 SO ASTRONOMICAL JOURNAL LA English DT Article ID INFRARED-EMISSION; SOLAR NEIGHBORHOOD; INTERSTELLAR DUST; GALAXY; GAS; MORPHOLOGY; HYDROGEN; DISK AB The high-mass star-formation rate and efficiency in the inner disk of M33 are measured using optical, far-infrared, and millimeter line data. The high-mass star-formation rate calculated from the H-alpha emission over an area of 4 kpc2 is 0.007 M . yr-1, which corresponds to a total star-formation rate of 0.04 M . yr-1. The high-mass star-formation rate obtained from the far-infrared emission is within a factor of 2 of the rate calculated from the H-alpha emission. However, star-formation rates obtained from H-alpha and far-infrared luminosities agree better in regions with warmer dust temperatures, which suggests that a substantial fraction of the far-infrared luminosity in cooler regions is from dust heated by an older stellar population. A lower limit to the high-mass star-formation rate deduced from number counts of blue, high-mass stars is consistent with the results obtained from the H-alpha and far-infrared emission. The high-mass star formation efficiency varies by a factor of 6 among six molecular complexes identified previously. However, both the southern spiral arm and the molecular complexes have star formation efficiencies similar to regions containing little molecular gas. Thus, star formation in the inner disk of M33 does not appear to be a nonlinear function of gas surface density. C1 CALTECH,DEPT ASTRON 105-24,PASADENA,CA 91125. CALTECH,INFRARED PROC & ANAL CTR,JET PROPULS LAB,PASADENA,CA 91125. NR 35 TC 24 Z9 24 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 APR PY 1991 VL 101 IS 4 BP 1293 EP 1298 DI 10.1086/115765 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE097 UT WOS:A1991FE09700013 ER PT J AU OWEN, WM VAUGHAN, RM SYNNOTT, SP AF OWEN, WM VAUGHAN, RM SYNNOTT, SP TI ORBITS OF THE 6 NEW SATELLITES OF NEPTUNE SO ASTRONOMICAL JOURNAL LA English DT Article ID RINGS AB Orbital elements are presented for the six satellites discovered by Voyager 2 at Neptune [B. A. Smith et al., Science, 246, 1422 (1989)]. All six are in nearly circular direct orbits. Most have low inclinations as well, but the innermost, 1989N6, is inclined 4-degrees.7 to Neptune's equator. RP OWEN, WM (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 21 TC 35 Z9 36 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 APR PY 1991 VL 101 IS 4 BP 1511 EP 1515 DI 10.1086/115783 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE097 UT WOS:A1991FE09700031 ER PT J AU SCHUTTE, WA GREENBERG, JM AF SCHUTTE, WA GREENBERG, JM TI EXPLOSIVE DESORPTION OF ICY GRAIN MANTLES IN DENSE CLOUDS SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ATOMIC AND MOLECULAR PROCESSES; INTERSTELLAR MEDIUM, ABUNDANCES; INTERSTELLAR MEDIUM, CLOUDS, GENERAL; INTERSTELLAR MEDIUM, DUST ID TIME-DEPENDENT CHEMISTRY; INTER-STELLAR CLOUDS; H-II REGIONS; MOLECULAR CLOUDS; INTERSTELLAR GRAINS; ABSORPTION FEATURES; INFRARED-SPECTRA; CARBON-MONOXIDE; RADIATION-FIELD; STAR FORMATION AB Due to the short timescale for the accretion of free molecules on grains in dense clouds (i.e. approximately 10(5) yr), an efficient desorption mechanism is required to replenish the gas phase material. As a possibility, we have investigated the explosive desorption which may take place when the ice mantle which condenses on the grain is heated sufficiently to release its potential chemical energy. At the low temperatures of interstellar grains (approximately 10 K), such energy can be stored in the form of frozen free radicals when the ice is photolysed by UV radiation. To study the efficiency of this desorption process, we did a laboratory investigation of the photochemical storage of free radicals in astrophysical ice analogues and of the sublimation upon the explosive energy release which occurred when the irradiated ice was rapidly heated. Using the laboratory results, we constructed a model of the desorption - accretion equilibrium in dense clouds. It was found that under certain conditions for the grain size distribution explosive desorption of the ice mantles can maintain a considerable amount of CO in the gas phase. More refractory molecules, however, are desorbed very inefficiently. This selective desorption leads to the depletion of the refractory molecules from the gas phase and the development of a layered ice mantle structure, i.e., of an inner mantle containing the refractory ices and an outer mantle consisting of condensed volatile molecules. Differences between our model and previous modelling of explosive grain mantle desorption are discussed. Finally, the results are compared to the available data on the chemical composition of the gas and ice in dense clouds. Possible implications of the nature of the desorption mechanism for the cloud chemistry are pointed out. C1 LEIDEN STATE UNIV, HUYGENS LAB, LAB ASTROPHYS GRP, 2300 RA LEIDEN, NETHERLANDS. RP SCHUTTE, WA (reprint author), NASA, AMES RES CTR, DIV SPACE SCI, MS 245-6, MOFFETT FIELD, CA 94035 USA. NR 100 TC 69 Z9 69 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 APR PY 1991 VL 244 IS 1 BP 190 EP 204 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FJ403 UT WOS:A1991FJ40300029 ER PT J AU KOLYUKA, Y TIKHONOV, V IVANOV, N POLYAKOV, V AVANESOV, G HEIFETZ, V ZHUKOV, B AKIM, E STEPANYANTS, V PAPKOV, O DUXBURY, T AF KOLYUKA, Y TIKHONOV, V IVANOV, N POLYAKOV, V AVANESOV, G HEIFETZ, V ZHUKOV, B AKIM, E STEPANYANTS, V PAPKOV, O DUXBURY, T TI PHOBOS AND DEIMOS ASTROMETRIC OBSERVATIONS FROM THE PHOBOS MISSION SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE ASTRONOMETRY; MARS; PHOBOS; DEIMOS; AND PHOBOS MISSION AB This article describes the reduced astrometric observations of Phobos and Deimos as derived from the Phobos Mission imaging data. These astrometric data span 2 months in 1989, contain 37 sets of spacecraft-centered, right ascension and declination observations of Phobos and 8 sets of Deimos. The Phobos observations have an orbital position accuracy of about 2 km (1 sigma) while the Deimos observations have an accuracy of about 10 km (1 sigma). The details of observations formulation and use for emphemeris improvement are given. C1 CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. MOSCOW FLIGHT CONTROL CTR, MOSCOW, USSR. MOSCOW SPACE RES INST, MOSCOW, USSR. BABAKIN CTR, MOSCOW, USSR. MV KELDYSH APPL MATH INST, MOSCOW, USSR. NR 8 TC 11 Z9 11 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 APR PY 1991 VL 244 IS 1 BP 236 EP 241 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FJ403 UT WOS:A1991FJ40300033 ER PT J AU KUSUNOSE, M AF KUSUNOSE, M TI 2-TEMPERATURE ACCRETION DISKS WITH WINDS IN A FLUID APPROXIMATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION; BLACK HOLES; GALAXIES; NUCLEI; HYDRODYNAMICS ID COMPTON HEATED WINDS; PAIR PRODUCTION; CYGNUS X-1; CORONAE; PLASMAS; DYNAMICS; MODEL AB We use the polytropic relation between pressure and density of wind gases to obtain solutions for optically thin, hot accretion disks with winds. We assume that cooling mechanisms in the disks are bremsstrahlung and Compton scattering. This extends the previous work of Takahara, Rosner, & Kusunose, which did not analyze winds within a self-consistent disk model. We show that the disks have winds for accretion rates higher than approximately 10% of the Eddington rate, depending on the viscosity parameter of the disks and the polytropic exponent of wind gases, gamma-w. The poloidal velocity of winds at the foot-point is shown to be as high as 10% of light speed. We obtain solutions with a mass-loss rate as high as 50% of the accretion rate given at the outer boundary for gamma-w = 5/3. As gamma-w approaches unity, the maximum allowable mass-loss rate decreases for a given accretion rate at the outer boundary. We also numerically show that the winds do not play an effective role to stabilize the disks against perturbations of the proton temperature. RP KUSUNOSE, M (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES65,HUNTSVILLE,AL 35812, USA. NR 18 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1991 VL 370 IS 2 BP 505 EP 510 DI 10.1086/169837 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FB172 UT WOS:A1991FB17200006 ER PT J AU BRUHWEILER, FC FITZURKA, MA GULL, TR AF BRUHWEILER, FC FITZURKA, MA GULL, TR TI A LARGE SUPERSHELL H-II REGION COMPLEX IN THE LARGE MAGELLANIC CLOUD AND THE INTERSTELLAR ENVIRONMENT OF SN-1987A SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES; MAGELLANIC CLOUDS; NEBULAE; H-II REGIONS; STARS; INDIVIDUAL (SN-1987A); STARS; SUPERNOVAE ID PROPAGATING STAR FORMATION; INITIAL MASS FUNCTION; WOLF-RAYET STARS; EVOLUTIONARY MODELS; STELLAR WINDS; NOVA REMNANTS; CARINA NEBULA; ETA-CARINAE; X-RAYS; LINES AB Optical narrow-bandpass imagery taken in the light of [O III], lambda-5007, reveals an unusually large, almost-equal-to 1 kpc, H II region complex in the LMC. This complex shows diffuse [O III] emission engulfing the 30 Doradus nebulosities and significant portions of Shapley's Constellation II, located to the west. The recent supernova, SN 1987A, also appears to have occurred inside this large ionized gas complex. Similar imagery acquired in the optical continuum at 4215 angstrom shows an even grander structure, a large dust ring, enclosing most of the diffuse [O III] emission. The dimensions of this structure, 1.5 x 2.0 kpc, are larger than the well-known supershell (LMC 4) enclosing Shapley's Constellation III. The dust ring likely delineates the periphery of a supershell structure and encompasses at least 830 OB stars with M(v) brighter than -4.2. Simple theoretical modelling suggests that the EUV radiation from these massive stars ionize the H II region complex, while their winds have served as the driving mechanism for the expansion of the dust ring supershell. The expansion of this supershell may have triggered the recent star formation activity in 30 Doradus. The implications for the recent IUE observations of SN 1987A and the ambient interstellar environment of SN 1987A are also discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP BRUHWEILER, FC (reprint author), CATHOLIC UNIV AMER,DEPT PHYS,HANNAN HALL,WASHINGTON,DC 20064, USA. RI Gull, Theodore/D-2753-2012 OI Gull, Theodore/0000-0002-6851-5380 NR 49 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1991 VL 370 IS 2 BP 551 EP & DI 10.1086/169841 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FB172 UT WOS:A1991FB17200010 ER PT J AU KALLMAN, TR RAYMOND, JC VRTILEK, SD AF KALLMAN, TR RAYMOND, JC VRTILEK, SD TI THE ULTRAVIOLET-SPECTRUM OF SCORPIUS X-1 AS OBSERVED BY IUE - 1978-1988 SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS; ACCRETION; STARS; INDIVIDUAL (SCORPIUS X-1); ULTRAVIOLET; SPECTRA; X-RAY; BINARIES ID COMPTON HEATED WINDS; X-RAY BINARIES; ACCRETION DISKS; BLACK-HOLES; CORONAE; SYSTEMS AB The IUE observations of Sco X-1 taken prior to 1988 September are summarized. These data are tested for variability associated with orbital motion and for correlations between the various observables. The continuum spectra are fitted to simple models for accretion disk atmospheres which demonstrate that X-ray heating dominates the outer regions of the accretion disk. Various scenarios for producing the observed line strengths and ratios are discussed. C1 HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. RP KALLMAN, TR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 665,GREENBELT,MD 20771, USA. NR 37 TC 14 Z9 14 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1991 VL 370 IS 2 BP 717 EP 729 DI 10.1086/169855 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FB172 UT WOS:A1991FB17200024 ER PT J AU KUIN, NPM POLAND, AI AF KUIN, NPM POLAND, AI TI OPACITY EFFECTS ON THE RADIATIVE LOSSES OF CORONAL LOOPS SO ASTROPHYSICAL JOURNAL LA English DT Article DE RADIATIVE TRANSFER; SUN; CORONA; SUN; FLARES; SUN; PROMINENCES ID QUIESCENT PROMINENCES; THERMAL-STABILITY; TRANSITION-REGION; SOLAR ATMOSPHERE; ENERGY-BALANCE; HYDRODYNAMICS; MODELS; SPECTRUM; HYDROGEN; EMISSION AB Hydrodynamic flux-tube calculations with energy balance provide us with one of our most basic modeling tools for understanding solar phenomena. These calculations are used for modeling features ranging from quiet-Sun loops to solar flares. A major limitation of these calculations is that they have used the optically thin approximation for calculating radiative energy losses. This assumption is not valid for hydrogen and helium in high-density loops. In this paper we present the results of calculations of radiative losses, which include the effects of geometry and optical depth, that can be used to improve the energy losses in many flux-tube calculations for loops with constant and variable cross sections. The results include the non-LTE ionization state of hydrogen and helium, thus allowing the determination of the ionization energy in the gas and the relative importance of collisional and radiative processes. These calculations show that optical depth effects are important under solar conditions in the temperature range of 8000-40,000 K. These results are presented in a form that can be easily incorporated in hydrodynamic flux-tube calculations. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,SOLAR PHYS BRANCH,GREENBELT,MD 20771. RP KUIN, NPM (reprint author), ST SYST CORP,LANHAM,MD, USA. NR 31 TC 25 Z9 25 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1991 VL 370 IS 2 BP 763 EP 774 DI 10.1086/169859 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FB172 UT WOS:A1991FB17200028 ER PT J AU PORTER, JG DERE, KP AF PORTER, JG DERE, KP TI THE MAGNETIC NETWORK LOCATION OF EXPLOSIVE EVENTS OBSERVED IN THE SOLAR TRANSITION REGION SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN; ACTIVITY; SUN; ATMOSPHERIC MOTIONS; SUN; FLARES; SUN; MAGNETIC FIELDS; SUN; TRANSITION REGION ID QUIET SUN; FIELD; ZONE; FLUX AB Compact, short-lived explosive events have been observed in solar transition region lines with the High-Resolution Telescope and Spectrograph (HRTS) flown by the Naval Research Laboratory on a series of rockets and on Spacelab 2. We present the first coalignment of such data, from Spacelab 2, with a simultaneous magnetogram and near-simultaneous He I lambda-10380 spectroheliogram obtained at the National Solar Observatory at Kitt Peak. The comparison shows that the explosive events occur in the solar magnetic network lanes at the boundaries of supergranular convective cells. However, the events occur away from the larger concentrations of magnetic flux in the network, in contradiction to the observed tendency of the more energetic solar phenomena to be associated with the stronger magnetic fields. C1 USN,RES LAB,WASHINGTON,DC 20375. RP PORTER, JG (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 22 TC 54 Z9 55 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1991 VL 370 IS 2 BP 775 EP & DI 10.1086/169860 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FB172 UT WOS:A1991FB17200029 ER PT J AU KURTZ, J ADAMOWICZ, L AF KURTZ, J ADAMOWICZ, L TI THEORETICAL VIBRATIONS OF CARBON CHAIN-C3, CHAIN-C4, CHAIN-C5, CHAIN-C6, CHAIN-C7, CHAIN-C8, AND CHAIN-C9 SO ASTROPHYSICAL JOURNAL LA English DT Article DE LINE IDENTIFICATIONS; MOLECULAR PROCESSES ID CLUSTERS; STABILITY; MOLECULES; C-5; SPECTROSCOPY; ISOMERS; BANDS; C5 AB The MBPT(2) procedure with the 6-31G* basis set was used to study nearly linear carbon chains. The theoretical vibrational frequencies of the molecules C3 through C-9 are presented and, for C3 through C6, compared to experimental stretching frequencies and their C-13/C-12 isotopomers. Predictions for C-7, C-8, and C-9 stretching frequencies are calculated by directly scaling the theoretical frequencies with factors derived from the experimental-to-theoretical ratios known for the smaller molecules. C1 UNIV ARIZONA,DEPT CHEM,TUCSON,AZ 85721. RP KURTZ, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 691,GREENBELT,MD 20771, USA. NR 28 TC 40 Z9 40 U1 1 U2 9 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1991 VL 370 IS 2 BP 784 EP 790 DI 10.1086/169862 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FB172 UT WOS:A1991FB17200031 ER PT J AU ERICKSON, EF COLGAN, SWJ SIMPSON, JP RUBIN, RH MORRIS, M HAAS, MR AF ERICKSON, EF COLGAN, SWJ SIMPSON, JP RUBIN, RH MORRIS, M HAAS, MR TI FAR-INFRARED LINE AND CONTINUUM OBSERVATIONS OF G0.095+0.012 AND THE E2 THERMAL RADIO FILAMENT NEAR THE GALACTIC-CENTER SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, NUCLEI; GALAXIES, THE GALAXY; INFRARED, SOURCES ID MODEL; ARC; ATMOSPHERES; IONIZATION; SATURN AB Measurements of far-infrared lines and continuum from G0.095 + 0.012 and the E2 thermal "arched" radio filament near the Galactic center are well explained by numerous embedded stars with T(eff) approximately 35,000 K. The structure of the filament and the apparent absence of hotter stars are qualitatively difficult to reconcile with this idea. C1 UNIV CALIF BERKELEY,SETI INST,BERKELEY,CA 94720. UNIV CALIF LOS ANGELES,DEPT ASTRON,156205,8979 MATH SCI BLDG,LOS ANGELES,CA 90024. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. RP ERICKSON, EF (reprint author), NASA,AMES RES CTR,MS 245-6,MOFFETT FIELD,CA 94035, USA. RI Colgan, Sean/M-4742-2014 NR 32 TC 30 Z9 30 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1991 VL 370 IS 2 BP L69 EP & DI 10.1086/185979 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FB173 UT WOS:A1991FB17300004 ER PT J AU WANNIER, PG ANDERSSON, BG MORRIS, M LICHTEN, SM AF WANNIER, PG ANDERSSON, BG MORRIS, M LICHTEN, SM TI WARM NEUTRAL HALOS AROUND MOLECULAR CLOUDS .2. H-I AND CO (J = 1-0) OBSERVATIONS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE INTERSTELLAR; MOLECULES, RADIO SOURCES; 21-CM RADIATION ID DARK CLOUDS; LAMBDA-ORIONIS; RESOLUTION; OUTFLOWS; OBJECTS; COMPLEX; REGION; TAURUS; L1551; GAS AB Observational data are presented relating to the boundary regions between dense, molecular clouds and the more diffuse atomic gas. The data set consists of H I 21 cm and CO (J = 1-0) strip maps in 14 molecule clouds which traverse 62 known CO cloud boundaries. The angular lengths of the strips range from 0.5-degrees to several degrees of arc, which is generally adequate to eliminate confusion with background (and foreground) H I. Most of the crossed boundaries (49 of 62) show clear evidence for the presence of H I emission maxima, or halos, lying outside the molecular clouds' gas. There is also general evidence for limb brightening in the CO emission. C1 GOTHENBURG UNIV,S-41124 GOTHENBURG,SWEDEN. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. RP WANNIER, PG (reprint author), CALTECH,JET PROP LAB,MAIL STOP 169-506,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 39 TC 26 Z9 26 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 APR PY 1991 VL 75 IS 4 BP 987 EP 998 DI 10.1086/191557 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FC835 UT WOS:A1991FC83500003 ER PT J AU PETEET, DM AF PETEET, DM TI POSTGLACIAL MIGRATION HISTORY OF LODGEPOLE PINE NEAR YAKUTAT, ALASKA SO CANADIAN JOURNAL OF BOTANY-REVUE CANADIENNE DE BOTANIQUE LA English DT Article DE ALASKA; POLLEN; MACROFOSSILS; LODGEPOLE PINE; PHYTOGEOGRAPHY ID BRITISH-COLUMBIA; CLIMATIC-CHANGE; VEGETATION HISTORY; THERMAL MAXIMUM; NORTH-AMERICA; CANADA; POLLEN; RECORD; FOREST AB Pollen stratigraphy from three peat sections near Yakutat, Alaska, suggests that lodgepole pine only recently arrived in southeastern Alaska. In contrast with this palynological interpretation, however, are lodgepole pine (Pinus contorta) macrofossils that are present throughout one entire peat core. C-14 dating by accelerator mass spectrometry confirms the establishment of lodgepole pine in this region of Alaska about 10 000 BP. The surprising disparity between the pollen and macrofossil results has important implications for paleomigration research. These results imply that the use of assigned pollen percentages to indicate the presence of a species within a region may not be valid, particularly where a species is at the edge of its geographic range. Comparison of the timing of the first appearance of lodgepole pine pollen from a dozen sections along the north Pacific coast suggests either a late Wisconsin refugium for this pine in southeastern Alaska or extremely rapid lateglacial coastal migration northwestward following ice retreat. C1 COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964. RP PETEET, DM (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 62 TC 53 Z9 53 U1 1 U2 4 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0008-4026 J9 CAN J BOT JI Can. J. Bot.-Rev. Can. Bot. PD APR PY 1991 VL 69 IS 4 BP 786 EP 796 PG 11 WC Plant Sciences SC Plant Sciences GA FP802 UT WOS:A1991FP80200010 ER PT J AU CARR, LW CHANDRASEKHARA, MS AF CARR, LW CHANDRASEKHARA, MS TI A STUDY OF COMPRESSIBILITY EFFECTS ON DYNAMIC STALL OF RAPIDLY PITCHING AIRFOILS SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article AB Results of recent experimental studies into the effect of compressibility on dynamic stall of oscillating airfoils are reviewed. Stroboscopic schlieren images of the strongly unsteady flow field are presented, showing the development of the dynamic stall vortex, and its progression down the airfoil. The effect of varying free-stream Mach number, and frequency of oscillation of the airfoil are demonstrated, and examples of local supersonic flow are presented, including the presence of a shock near the leading edge of the airfoil. C1 USA,AEROFLIGHTDYNAM DIRECTORATE,AVSCOM,MOFFETT FIELD,CA 94035. NASA,NAVAL POSTGRAD SCH,JOINT INST AERONAUT,DEPT AERONAUT & ASTRONAUT,MONTEREY,CA 94943. RP CARR, LW (reprint author), NASA,AMES RES CTR,FLUID MECH LAB,MOFFETT FIELD,CA 94035, USA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD APR PY 1991 VL 65 IS 1-3 BP 62 EP 68 DI 10.1016/0010-4655(91)90155-E PG 7 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA FM805 UT WOS:A1991FM80500009 ER PT J AU GOODRICH, JW GUSTAFSON, K HALASI, K AF GOODRICH, JW GUSTAFSON, K HALASI, K TI TIME-ASYMPTOTIC FLOW CALCULATION SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article ID FINITE-ELEMENT APPROXIMATION; NAVIER-STOKES PROBLEM; SPATIAL DISCRETIZATION; CAVITY; TRANSITION; EQUATIONS AB This paper presents some indicators for monitoring the development of a flow, for identifying an asymptotic flow state, and for presenting the qualitative nature of that state. Experiences with computing time-asymptotic flow states are discussed, with some lessons which have been learned along the way. C1 UNIV COLORADO,DEPT MATH,BOULDER,CO 80309. KANSAS STATE UNIV AGR & APPL SCI,DEPT MATH,MANHATTAN,KS 66506. RP GOODRICH, JW (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 18 TC 2 Z9 2 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD APR PY 1991 VL 65 IS 1-3 BP 107 EP 116 DI 10.1016/0010-4655(91)90161-D PG 10 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA FM805 UT WOS:A1991FM80500015 ER PT J AU MACARAEG, MG AF MACARAEG, MG TI INVESTIGATION OF SUPERSONIC MODES AND 3-DIMENSIONALITY IN BOUNDED, FREE SHEAR FLOWS SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article AB It is found through two-dimensional temporal simulations of high-speed free shear layers that mean flow distortion is significantly increased when supersonic disturbances are introduced as initial conditions. The shear layer exhibits no subharmonic growth or roll-up, but rather a spectral broadening as energy is distributed into higher harmonics. Increasing the velocity of one side of the mixing layer (u2) to roughly 1/5 the speed of the high speed side (u1), allows a slight subharmonic growth at a very slow rate for two-dimensional modes. A first look at three-dimensional free shear flows is also presented for M = 2. No effect is seen for incompressible flow; however, stabilization is seen with respect to maximum temporal growth rates as the transverse velocity is increased. A much stronger, but similar effect is seen if u2 is increased. The wave direction of maximum growth for u2 > 0.4 is found to be the direction of the faster stream (u1) over a broad range of transverse velocities. RP MACARAEG, MG (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 7 TC 1 Z9 1 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD APR PY 1991 VL 65 IS 1-3 BP 201 EP 208 DI 10.1016/0010-4655(91)90172-H PG 8 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA FM805 UT WOS:A1991FM80500026 ER PT J AU PIOMELLI, U ZANG, TA AF PIOMELLI, U ZANG, TA TI LARGE-EDDY SIMULATION OF TRANSITIONAL CHANNEL FLOW SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article ID WALL-BOUNDED FLOWS AB A large-eddy simulation (LES) of transition in plane channel flow has been carried out. The LES results have been compared with those of a fine direct numerical simulation (DNS), and with those of a coarse DNS that uses the same mesh as the LES, but no residual stress model. While at the early stages of transition LES and coarse DNS give the same results, the presence of the residual stress model was found to be necessary to predict accurately mean velocity and Reynolds stress profiles during the late stages of transition (after the second spike stage). The evolution of single Fourier modes is also predicted more accurately by the LES than by the coarse DNS. As small scales are generated, the dissipative character of the residual stress causes it to reproduce correctly the energy cascade; as transition progresses, then, and the flow approaches its fully developed turbulent state, the subgrid scales tend towards equilibrium and the model becomes more accurate. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP PIOMELLI, U (reprint author), UNIV MARYLAND,DEPT MECH ENGN,COLLEGE PK,MD 20742, USA. NR 15 TC 22 Z9 22 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD APR PY 1991 VL 65 IS 1-3 BP 224 EP 230 DI 10.1016/0010-4655(91)90175-K PG 7 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA FM805 UT WOS:A1991FM80500029 ER PT J AU WONG, YS JIANG, H AF WONG, YS JIANG, H TI NUMERICAL SIMULATIONS FOR TRANSONIC AERODYNAMIC FLOWS SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article AB Transonic flow is an important aerodynamic phenomenon that occurs in the high subsonic Mach number flight regime. This paper presents the development of a numerical simulation for three-dimensional transonic aerodynamic flows around an isolated wing. The mathematical formulation is based on a transonic small-disturbance equation, which is a nonlinear and mixed elliptic-hyperbolic partial-differential equation. A Newton-like iterative scheme is developed for solving the transonic equation, and it is used in conjunction with a preconditioned minimal-residual algorithm. The numerical technique is proven to be efficient and reliable. Computational results for transonic flows around the ONERA M6 wing are presented. C1 NASA,LEWIS RES CTR,INST COMPUTAT MECH PROP,CLEVELAND,OH 44135. RP WONG, YS (reprint author), UNIV ALBERTA,DEPT MATH,EDMONTON T6G 2G1,ALBERTA,CANADA. NR 9 TC 1 Z9 1 U1 1 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0010-4655 J9 COMPUT PHYS COMMUN JI Comput. Phys. Commun. PD APR PY 1991 VL 65 IS 1-3 BP 310 EP 319 DI 10.1016/0010-4655(91)90184-M PG 10 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA FM805 UT WOS:A1991FM80500038 ER PT J AU HALL, FG BOTKIN, DB STREBEL, DE WOODS, KD GOETZ, SJ AF HALL, FG BOTKIN, DB STREBEL, DE WOODS, KD GOETZ, SJ TI LARGE-SCALE PATTERNS OF FOREST SUCCESSION AS DETERMINED BY REMOTE-SENSING SO ECOLOGY LA English DT Article DE BIOSPHERE; ECOSYSTEM DYNAMICS; GLOBAL CHANGE; LANDSCAPE ECOLOGY; LONG-TERM ECOLOGICAL RESEARCH; STABILITY; SUCCESSION ID BOREAL FOREST; AREA; MINNESOTA; REFLECTANCE; DYNAMICS; CLIMATE; POLLEN; CARBON; LAKE AB The spatial pattern of and the transition rates between forest ecological states were inferred for almost-equal-to 260000 pixel-sized (3600 m2) landscape units using satellite remote sensing. Transition rates were estimated from 1973 to 1983 Landsat images of the study area, classified into ecological states associated with forest succession. The effects of classification error on transition rate estimates were modeled and error adjustments made. Classification of the 1973 and 1983 Landsat images of the 900 km2 study region required a relatively small set of ground-observed and photo-interpreted plots in 1983, with a total area of just 1.62 km2. An innovative technique for correcting multiyear Landsat images for between-image differences in atmospheric effects and sensor calibration, permitted classification of the 1973 Landsat image using 1983 ground observations. Given current Landsat data, and ground observations in one year, this technique would permit monitoring of forest succession and dynamics for nearly a 20-yr period. Results of applying these techniques to a forest ecosystem showed that during the 10-yr observation period it was patchy and dynamic. For both a wilderness and a nonwilderness area in the study region, sizeable values of transition rates were observed and over half of the landscape units were observed to change state; however, a Markov analysis, using the observed transition probabilities, suggests that at the regional level neither the wilderness nor the nonwilderness areal proportions of ecological states are undergoing rapid change. C1 UNIV CALIF SANTA BARBARA,DEPT BIOL SCI,SANTA BARBARA,CA 93106. UNIV CALIF SANTA BARBARA,ENVIRONM STUDIES PROGRAM,SANTA BARBARA,CA 93106. VERSAR,COLUMBIA,MD 20771. BENNINGTON COLL,DIV SCI,BENNINGTON,VT 05201. SCI APPLICAT RES,LANHAM,MD 20771. RP HALL, FG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 923,GREENBELT,MD 20771, USA. RI Goetz, Scott/A-3393-2015 OI Goetz, Scott/0000-0002-6326-4308 NR 47 TC 194 Z9 201 U1 7 U2 44 PU ECOLOGICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE, NW, STE 400, WASHINGTON, DC 20036 SN 0012-9658 J9 ECOLOGY JI Ecology PD APR PY 1991 VL 72 IS 2 BP 628 EP & DI 10.2307/2937203 PG 0 WC Ecology SC Environmental Sciences & Ecology GA FE248 UT WOS:A1991FE24800021 ER PT J AU FISHMAN, J AF FISHMAN, J TI PROBING PLANETARY POLLUTION FROM SPACE SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Article ID TROPOSPHERIC OZONE; INSITU MEASUREMENTS; CARBON-MONOXIDE; VARIABILITY; TRANSPORT; CLIMATE; LIDAR RP FISHMAN, J (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,CHEM & DYNAM BRANCH,HAMPTON,VA 23665, USA. NR 32 TC 22 Z9 22 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0013-936X J9 ENVIRON SCI TECHNOL JI Environ. Sci. Technol. PD APR PY 1991 VL 25 IS 4 BP 612 EP 621 DI 10.1021/es00016a004 PG 10 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA FE652 UT WOS:A1991FE65200011 ER PT J AU RUDAZ, AO DAVIDSON, EA FIRESTONE, MK AF RUDAZ, AO DAVIDSON, EA FIRESTONE, MK TI SOURCES OF NITROUS-OXIDE PRODUCTION FOLLOWING WETTING OF DRY SOIL SO FEMS MICROBIOLOGY ECOLOGY LA English DT Article DE DENITRIFICATION; NITRIFICATION; N2O; NITROGEN CYCLE ID 2 FORESTED ECOSYSTEMS; HETEROTROPHIC NITRIFICATION; ANNUAL GRASSLAND; ENZYME-ACTIVITY; DENITRIFICATION; VARIABILITY; ACETYLENE; DYNAMICS; NITRATE; LOSSES AB Production of N2O was detected within 30 min of adding water to very dry soil (matric water potential < -9 MPa) sampled at the end of the dry season from an annual grassland of California, U.S.A. Using C2H2 to inhibit nitrification, we demonstrate that nitrification was a modest source of N2O in sieved soil wetted to a water content below field capacity, but that denitrification was the major source of N2O in sieved soils wetted to a water content above field capacity and in intact cores wetted either below or above field capacity. Significant abiological sources of N2O were not detected. De novo enzyme synthesis began within 4-8 h of wetting, and denitrifying enzyme activity doubled within 26 h, indicating that denitrifying bacteria can quickly transform their metabolic state from adaptation to severe drought stress to rapid exploitation of changing resources. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF BERKELEY,DEPT SOIL SCI,BERKELEY,CA 94720. RP RUDAZ, AO (reprint author), SWISS FED RES STN AGR CHEM & HYG ENVIRONM,CH-3097 LIEBEFELD,SWITZERLAND. RI Davidson, Eric/K-4984-2013 OI Davidson, Eric/0000-0002-8525-8697 NR 25 TC 74 Z9 80 U1 1 U2 41 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-6496 J9 FEMS MICROBIOL ECOL JI FEMS Microbiol. Ecol. PD APR PY 1991 VL 85 IS 2 BP 117 EP 124 PG 8 WC Microbiology SC Microbiology GA FK646 UT WOS:A1991FK64600004 ER PT J AU SOMERTON, DA KOBAYASHI, DR AF SOMERTON, DA KOBAYASHI, DR TI ROBUSTNESS OF THE WETHERALL LENGTH-BASED METHOD TO POPULATION DISEQUILIBRIA SO FISHERY BULLETIN LA English DT Article ID HAWAIIAN AB For fish populations in equilibrium, estimates of Z/K and L infinity can be obtained solely from length-frequency data by using the Wetherall length-based method. Robustness of this method to departures from equilibrium conditions is examined with a population simulation model. During disequilibrium conditions following either the initiation of a fishery or a 1-year perturbation in recruitment, estimates of both parameters, especially Z/K, are severely biased. Three-year averaging of catch length-frequencies does not substantially reduce this bias. A test, based on the chi-square statistic, is proposed for detecting population disequilibrium. Provided that the sizes of length-frequency samples are sufficiently large, the test is an effective way to detect population disequilibrium and thereby avoid biased parameter estimates. RP SOMERTON, DA (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 12 TC 3 Z9 3 U1 0 U2 0 PU NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE PI SEATTLE PA 7600 SAND POINT WAY NE BIN C15700, SEATTLE, WA 98115 SN 0090-0656 J9 FISH B-NOAA JI Fish. Bull. PD APR PY 1991 VL 89 IS 2 BP 307 EP 314 PG 8 WC Fisheries SC Fisheries GA FR767 UT WOS:A1991FR76700011 ER PT J AU NEWMAN, P STOLARSKI, R SCHOEBERL, M MCPETERS, R KRUEGER, A AF NEWMAN, P STOLARSKI, R SCHOEBERL, M MCPETERS, R KRUEGER, A TI THE 1990 ANTARCTIC OZONE HOLE AS OBSERVED BY TOMS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID DEPLETION AB The 1990 Antarctic ozone hole matched the record 1987 ozone hole in depth, duration, and area. During the formation phase of the hole (August), total ozone values were the lowest yet recorded. The decline rate approximately matched the record 1987 decline, and reached a minimum of 125 Dobson Units on October 4, 1990. October total ozone averages were marginally higher than 1987. As during 1987, the 1990 total ozone values within the hole slowly and steadily increased during the mid-October through November period. The ozone hole breakup was the latest yet recorded (early December), with low ozone values persisting over the pole through December, setting a record low for December average polar ozone. Temperatures were near average during the early spring, but were below normal for the late-spring. Temperatures in the early spring of 1990 were substantially warmer than those observed in the early spring of 1987. RP NEWMAN, P (reprint author), NOAA,GODDARD SPACE FLIGHT CTR,CODE 916,ROCKVILLE,MD 20852, USA. RI Newman, Paul/D-6208-2012; Stolarski, Richard/B-8499-2013; McPeters, Richard/G-4955-2013 OI Newman, Paul/0000-0003-1139-2508; Stolarski, Richard/0000-0001-8722-4012; McPeters, Richard/0000-0002-8926-8462 NR 18 TC 19 Z9 19 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR PY 1991 VL 18 IS 4 BP 661 EP 664 DI 10.1029/91GL00546 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FG828 UT WOS:A1991FG82800022 ER PT J AU MICHELANGELI, DV ALLEN, M YUNG, YL AF MICHELANGELI, DV ALLEN, M YUNG, YL TI HETEROGENEOUS REACTIONS WITH NACL IN THE EL CHICHON VOLCANIC AEROSOLS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC HYDROGEN-CHLORIDE; ACTIVE CHLORINE; ANTARCTIC OZONE; CLOUD; ERUPTION; TEMPERATURE; PARTICLES; DIOXIDE; NITRATE; LIDAR AB Previous investigations of the effects of the 1982 eruption of the El Chichon volcano could not explain all the observations of changes in O3, HCl, NO and NO2 simultaneously without proposing unproven chemical reactions. Since reactions between solid NaCl and gaseous ClNO3 and N2O5 rapidly produce photochemically active chlorine species and solid NaNO3 in laboratory experiments, we suggest that these reactions could have occurred with the NaCl observed to be present in the El Chichon sulfuric acid aerosols. As a consequence, we predict that HCl should increase substantially, while NO(x) should decrease, in agreement with the measurements after the eruption. Ozone should only be slightly affected by these reactions. Reactions between solid NaCl and the acids H2SO4 and HNO3 might prove to be important, but we lack sufficient evidence regarding their efficiency and the presence of HNO3 in the aerosols to be more conclusive. C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP MICHELANGELI, DV (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 32 TC 27 Z9 27 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR PY 1991 VL 18 IS 4 BP 673 EP 676 DI 10.1029/91GL00547 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FG828 UT WOS:A1991FG82800025 ER PT J AU KNIPP, DJ RICHMOND, AD EMERY, B CROOKER, NU DELABEAUJARDIERE, O EVANS, D KROEHL, H AF KNIPP, DJ RICHMOND, AD EMERY, B CROOKER, NU DELABEAUJARDIERE, O EVANS, D KROEHL, H TI IONOSPHERIC CONVECTION RESPONSE TO CHANGING IMF DIRECTION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; MAPPING ELECTRODYNAMIC FEATURES; HIGH-LATITUDE IONOSPHERE; ELECTRIC-FIELD; LOCALIZED OBSERVATIONS; PATTERNS AB By combining ground-based and satellite-based measurements of ionospheric electric fields, conductivities and magnetic perturbations, we are able to examine the characteristics of instantaneous, ionospheric convection patterns associated with changing directions of the Interplanetary Magnetic Field (IMF). In response to a rapid southward-to-northward turning of the IMF on 23 July 1983, the ionospheric convection reconfigured over a period of 40 minutes. The configuration changed from a conventional two-cell pattern to a contracted four-cell pattern, with reversed convection cells in the high-latitude dayside, associated with a strong potential drop of about 75 kV. Later, in response to a gradual rotation of the IMF from the +Z through the -Y toward the -Z direction, the nightside cells disappeared and the dawn cell in the reversed pair wrapped around and displaced the dusk cell until a conventional two-cell pattern was reestablished, largely in accord with the qualitative model of Crooker [1988]. Our results suggest that multiple cells can arise as a result of strong southward to northward transitions in the IMF. They appear to persist for sometime thereafter. C1 NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. GEOPHYS LAB,DIV SPACE PHYS,WASHINGTON,DC. SRI INT,MENLO PK,CA 94025. NASA,DIV SPACE PHYS,WASHINGTON,DC 20546. NOAA,NATL GEOPHYS DATA CTR,BOULDER,CO 80303. RP KNIPP, DJ (reprint author), USAF ACAD,DEPT PHYS,COLORADO SPRINGS,CO 80840, USA. NR 20 TC 56 Z9 56 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD APR PY 1991 VL 18 IS 4 BP 721 EP 724 DI 10.1029/90GL02592 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FG828 UT WOS:A1991FG82800037 ER PT J AU KOIKE, M KONDO, Y HAYASHI, M IWASAKA, Y NEWMAN, PA HELTEN, M AIMEDIEU, P AF KOIKE, M KONDO, Y HAYASHI, M IWASAKA, Y NEWMAN, PA HELTEN, M AIMEDIEU, P TI DEPLETION OF ARCTIC OZONE IN THE WINTER 1990 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB Ozone mixing ratios were measured by ozonesondes on board balloons launched from Esrange, near Kiruna, Sweden (68-degrees-N, 20-degrees-E) from January 11 to February 9, 1990. The data obtained prior to a sudden warming on February 7, 1990 show that at potential temperatures between 460 and 640 K, the ozone mixing ratio just inside the polar vortex was systematically smaller than that outside, the largest difference being 29 % at around 525 K. The ozone mixing ratio at 525 K inside the vortex decreased at a rate of about 1.5 % per day between January 26 and February 4. The temperatures simultaneously observed were quite often low enough to allow for formation of nitric acid trihydrate (NAT) particles around this altitude. Depletion of ozone due to highly perturbed chemical conditions in late January and early February is strongly suggested. C1 FORSCHUNGZENTRUM,INST CHEM 2,W-5170 JULICH,GERMANY. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. CNRS,SERV AERON,F-91370 VERRIERES BUISSON,FRANCE. RP KOIKE, M (reprint author), NAGOYA UNIV,SOLAR TERR ENVIRONM LAB,TOYOKAWA,AICHI,JAPAN. RI Koike, Makoto/F-4366-2011; Kondo, Yutaka/D-1459-2012; Newman, Paul/D-6208-2012 OI Newman, Paul/0000-0003-1139-2508 NR 12 TC 10 Z9 10 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 APR PY 1991 VL 18 IS 4 BP 791 EP 794 DI 10.1029/91GL00467 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FG828 UT WOS:A1991FG82800055 ER PT J AU WILSON, JW CUCINOTTA, FA HAJNAL, F AF WILSON, JW CUCINOTTA, FA HAJNAL, F TI ANALYTICAL RELATIONSHIPS OF NUCLEAR-FIELD AND MICRODOSIMETRIC QUANTITIES FOR TARGET FRAGMENTATION IN TISSUE SYSTEMS SO HEALTH PHYSICS LA English DT Article ID WATER AB A simple analytic formula for the nuclear fields formed by target fragmentation in tissue systems is derived using the continuous slowing down approximation (CSDA). The energy fluctuations in sensitive localized sites within the tissue system caused by these nuclear events are defined by microdosimetry. In that CSDA is used, the energy fluctuations exclude the role of secondary electrons. The relations also relate to the response of microdosimetric devices to nuclear fragmentation fields. C1 US DOE, ENVIRONM MEASUREMENTS LAB, NEW YORK, NY 10014 USA. RP WILSON, JW (reprint author), NASA, LANGLEY RES CTR, HAMPTON, VA 23665 USA. NR 19 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT WILLIAMS & WILKINS PI PHILADELPHIA PA 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA SN 0017-9078 EI 1538-5159 J9 HEALTH PHYS JI Health Phys. PD APR PY 1991 VL 60 IS 4 BP 559 EP 565 DI 10.1097/00004032-199104000-00010 PG 7 WC Environmental Sciences; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging SC Environmental Sciences & Ecology; Public, Environmental & Occupational Health; Nuclear Science & Technology; Radiology, Nuclear Medicine & Medical Imaging GA FD282 UT WOS:A1991FD28200010 PM 2001952 ER PT J AU HABERLE, RM JAKOSKY, BM AF HABERLE, RM JAKOSKY, BM TI ATMOSPHERIC EFFECTS ON THE REMOTE DETERMINATION OF THERMAL INERTIA ON MARS SO ICARUS LA English DT Article ID VIKING LANDING SITES; PHYSICAL-PROPERTIES; MARTIAN ATMOSPHERE; DUST STORMS; SURFACE; TEMPERATURES; CIRCULATION; BEHAVIOR; OPACITY; CLOUDS C1 UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. UNIV COLORADO,DEPT GEOL SCI,BOULDER,CO 80309. RP HABERLE, RM (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,245-3,MOFFETT FIELD,CA 94035, USA. NR 52 TC 89 Z9 89 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 1991 VL 90 IS 2 BP 187 EP 204 DI 10.1016/0019-1035(91)90100-8 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH195 UT WOS:A1991FH19500001 ER PT J AU RIZK, B WELLS, WK HUNTEN, DM STOKER, CR FREEDMAN, RS ROUSH, T POLLACK, JB HABERLE, RM AF RIZK, B WELLS, WK HUNTEN, DM STOKER, CR FREEDMAN, RS ROUSH, T POLLACK, JB HABERLE, RM TI MERIDIONAL MARTIAN WATER ABUNDANCE PROFILES DURING THE 1988-1989 SEASON SO ICARUS LA English DT Article ID VAPOR OBSERVATIONS; POLAR CAPS; MARS; VIKING; ATMOSPHERE; CYCLE; REGOLITH C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP RIZK, B (reprint author), UNIV ARIZONA,DEPT PLANETARY SCI,LUNAR & PLANETARY LAB,TUCSON,AZ 85721, USA. NR 29 TC 28 Z9 28 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 APR PY 1991 VL 90 IS 2 BP 205 EP 213 DI 10.1016/0019-1035(91)90101-X PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH195 UT WOS:A1991FH19500002 ER PT J AU MCKAY, CP DAVIS, WL AF MCKAY, CP DAVIS, WL TI DURATION OF LIQUID WATER HABITATS ON EARLY MARS SO ICARUS LA English DT Article ID OBLIQUITY OSCILLATIONS; PLANETARY-ATMOSPHERES; MARTIAN PALEOCLIMATE; CLIMATIC-CHANGE; CARBON-DIOXIDE; ANTARCTIC LAKE; ICE; EVOLUTION; VALLEYS; ORIGIN RP MCKAY, CP (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 45 TC 91 Z9 94 U1 0 U2 5 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 APR PY 1991 VL 90 IS 2 BP 214 EP 221 DI 10.1016/0019-1035(91)90102-Y PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH195 UT WOS:A1991FH19500003 PM 11538097 ER PT J AU LOCKWOOD, GW THOMPSON, DT HAMMEL, HB BIRCH, P CANDY, M AF LOCKWOOD, GW THOMPSON, DT HAMMEL, HB BIRCH, P CANDY, M TI NEPTUNE CLOUD STRUCTURE IN 1989 - PHOTOMETRIC VARIATIONS AND CORRELATION WITH GROUND-BASED IMAGES SO ICARUS LA English DT Article ID ROTATION PERIOD; METHANE-BAND; WAVELENGTHS; URANUS C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. PERTH OBSERV,BICKLEY,WA 6076,AUSTRALIA. RP LOCKWOOD, GW (reprint author), LOWELL OBSERV,1400 W MARS HILL RD,FLAGSTAFF,AZ 86001, USA. NR 27 TC 9 Z9 9 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 APR PY 1991 VL 90 IS 2 BP 299 EP 307 DI 10.1016/0019-1035(91)90108-6 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH195 UT WOS:A1991FH19500009 ER PT J AU WEST, RA SMITH, PH AF WEST, RA SMITH, PH TI EVIDENCE FOR AGGREGATE PARTICLES IN THE ATMOSPHERES OF TITAN AND JUPITER SO ICARUS LA English DT Note ID POLARIMETRY; PHOTOMETRY; AEROSOLS; GRAINS C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. RP WEST, RA (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,MS 169-237,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 117 Z9 117 U1 1 U2 7 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 APR PY 1991 VL 90 IS 2 BP 330 EP 333 DI 10.1016/0019-1035(91)90113-8 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH195 UT WOS:A1991FH19500014 ER PT J AU KELLER, RM AF KELLER, RM TI APPLYING KNOWLEDGE COMPILATION TECHNIQUES TO MODEL-BASED REASONING SO IEEE EXPERT-INTELLIGENT SYSTEMS & THEIR APPLICATIONS LA English DT Article RP KELLER, RM (reprint author), NASA,AMES RES CTR,ARTIFICIAL INTELLIGENCE RES BRANCH,MS 244-17,MOFFETT FIELD,CA 94035, USA. NR 0 TC 5 Z9 5 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0885-9000 J9 IEEE EXPERT JI IEEE Expert-Intell. Syst. Appl. PD APR PY 1991 VL 6 IS 2 BP 82 EP 87 DI 10.1109/64.79715 PG 6 WC Computer Science, Artificial Intelligence; Engineering, Electrical & Electronic SC Computer Science; Engineering GA FG168 UT WOS:A1991FG16800015 ER PT J AU TRAHAN, RE YEADON, DS THIELE, MG AF TRAHAN, RE YEADON, DS THIELE, MG TI TOWFISH ALTITUDE COMPUTATION USING MULTIPATH ACOUSTIC RANGING SO IEEE JOURNAL OF OCEANIC ENGINEERING LA English DT Article DE TOWED CABLES; ACOUSTIC RANGING; TOWFISH ALTITUDE ID DYNAMICS AB A new technique is presented which uses an acoustic ranging technique to estimate towfish altitude; i.e., the height of the towfish above the seafloor. The ranging algorithm is an implementation of path-length calculation for acoustic signals generated at the towfish and received by a hydrophone located at the towing ship. The time delay between the direct and bottom-reflected signals is measured. Knowing the towfish depth and layback distance, the time delay can be used to compute the towfish altitude. C1 NAVAL OCEAN RES & DEV ACTIVITIES,STENNIS SPACE CTR,ADV TECHNOL BRANCH,NSTL STN,MS 39529. RP TRAHAN, RE (reprint author), UNIV NEW ORLEANS,DEPT ELECT ENGN,NEW ORLEANS,LA 70148, USA. NR 7 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 0364-9059 J9 IEEE J OCEANIC ENG JI IEEE J. Ocean. Eng. PD APR PY 1991 VL 16 IS 2 BP 212 EP 216 DI 10.1109/48.84138 PG 5 WC Engineering, Civil; Engineering, Ocean; Engineering, Electrical & Electronic; Oceanography SC Engineering; Oceanography GA FE664 UT WOS:A1991FE66400005 ER PT J AU TRAHAN, RE YEADON, DS THIELE, MG AF TRAHAN, RE YEADON, DS THIELE, MG TI OPTIMAL ESTIMATION OF LAYBACK DISTANCE FOR MARINE TOWED CABLES SO IEEE JOURNAL OF OCEANIC ENGINEERING LA English DT Article DE TOWED CABLES; OPTIMIZATION; LAYBACK DISTANCE ID DYNAMICS AB The estimation of towfish layback distance is usually performed with computer programs which implement numerical integration of system differential equations. The system dynamic model usually includes an estimate of coefficients of drag and velocities of the towfish and cable. Often these quantities are unknown or estimated with a great deal of uncertainty. The technique reported here uses an optimization approach to circumvent the estimates of critical parameters, and instead uses accurate measurements of towfish depth and length of cable payed out. A criterion is formulated and then minimized using a simple gradient-optimization method. The simulation results indicate that the method works well and can be implemented in a real-time data-acquisition system. C1 NAVAL OCEAN RES & DEV,STENNIS SPACE CTR,ADV TECHNOL BRANCH,NSTL STN,MS 39529. RP TRAHAN, RE (reprint author), UNIV NEW ORLEANS,DEPT ELECT ENGN,NEW ORLEANS,LA 70148, USA. NR 13 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 0364-9059 J9 IEEE J OCEANIC ENG JI IEEE J. Ocean. Eng. PD APR PY 1991 VL 16 IS 2 BP 217 EP 222 DI 10.1109/48.84139 PG 6 WC Engineering, Civil; Engineering, Ocean; Engineering, Electrical & Electronic; Oceanography SC Engineering; Oceanography GA FE664 UT WOS:A1991FE66400006 ER PT J AU BROWN, GM GOUDA, MG MILLER, RE AF BROWN, GM GOUDA, MG MILLER, RE TI BLOCK ACKNOWLEDGMENT - REDESIGNING THE WINDOW PROTOCOL SO IEEE TRANSACTIONS ON COMMUNICATIONS LA English DT Article ID VERIFICATION AB We describe a new version of the window protocol where message sequence numbers are taken from a finite domain and where both message disorder and loss can be tolerated. Most existing window protocols achieve only one of these two goals. Our protocol is based on a new method of acknowledgement, called block acknowledgement where each acknowledgement message has two numbers m and n to acknowledge the reception of all data messages with sequence numbers ranging from m to n. Using this method of acknowledgement, the proposed protocol achieves the two goals while maintaining the same data transmission capability of the traditional window protocol. C1 UNIV TEXAS,DEPT COMP SCI,AUSTIN,TX 78712. UNIV MARYLAND,DEPT COMP SCI,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,USRA CTR EXCELLANCE SPACE DATA & INFORMAT SCI,GREENBELT,MD 20771. RP BROWN, GM (reprint author), CORNELL UNIV,SCH ELECT ENGN,ITHACA,NY 14853, USA. NR 14 TC 7 Z9 7 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0090-6778 J9 IEEE T COMMUN JI IEEE Trans. Commun. PD APR PY 1991 VL 39 IS 4 BP 524 EP 532 DI 10.1109/26.81740 PG 9 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA FP650 UT WOS:A1991FP65000010 ER PT J AU RAJAGOPAL, M MILLER, RE AF RAJAGOPAL, M MILLER, RE TI SYNTHESIZING A PROTOCOL CONVERTER FROM EXECUTABLE PROTOCOL TRACES SO IEEE TRANSACTIONS ON COMPUTERS LA English DT Article DE COMMON PROTOCOL FUNCTION; CONVERTER SPECIFICATION; LEGAL TRACE; MAXIMAL TRACE; MESSAGE RELATIONSHIP; PDU LEVEL CONVERSION; PROTOCOL CONVERSION ALGORITHM; PROTOCOL FUNCTION; PROTOCOL FUNCTION TREE (PFT); SEMANTIC SPECIFICATION ID TRANSPORT; SNA AB Communicating finite state machines (CFSM's) with FIFO queues are used to model a protocol converter. A protocol conversion algorithm is developed and presented for the CFSM model of the protocols A and B. A converter H for protocols A = (A0, A1) and B = (B0, B1) is viewed as a black box such that H is between sender A0 and receiver B1. This gives a resulting protocol X = (A0, H, B1). The conversion algorthm requires a specification of the message relationships between the messages of protocols A and B. It is assumed that protocols A and B have the required progress properties. The algorithm includes a search for related messages from the two protocols in a FIFO from a composite space formed by a Cartesian cross-product of state spaces A1 and B0. The search produces finite length traces which are combined to form a state machine H which is examined for freedom from unspecified receptions, deadlocks, and livelocks. A protocol conversion example demonstrates the applicability of the algorithm. C1 GEORGIA INST TECHNOL,ATLANTA,GA 30332. NASA,GODDARD SPACE FLIGHT CTR,CTR EXCELLENCE SPACE DATA & INFORMAT SCI,GREENBELT,MD 20771. UNIV MARYLAND,COMP SCI,COLLEGE PK,MD 20742. RP RAJAGOPAL, M (reprint author), IBM CORP,LEXINGTON,KY 40503, USA. NR 22 TC 17 Z9 17 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0018-9340 J9 IEEE T COMPUT JI IEEE Trans. Comput. PD APR PY 1991 VL 40 IS 4 BP 487 EP 499 DI 10.1109/12.88468 PG 13 WC Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic SC Computer Science; Engineering GA FQ580 UT WOS:A1991FQ58000011 ER PT J AU PRESTAGE, JD DICK, GJ MALEKI, L AF PRESTAGE, JD DICK, GJ MALEKI, L TI LINEAR ION TRAP BASED ATOMIC FREQUENCY STANDARD SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Article AB Our goal at the Time and Frequency Systems Research group at JPL is the development of a trapped ion-based fieldable frequency standard with stability 1 x 10(-13)/square-root-tau for averaging times tau > 1 x 10(4) s. To achieve this goal we have developed a hybrid RF/dc linear ion trap which permits storage of large numbers of ions with reduced susceptibility to the second-order Doppler effect caused by the RF confining fields. We have confined Hg-199+ ions in this trap and have measured very high Q transitions with good signal to noise. In preliminary measurements we have obtained stabilities of 1.6 x 10(-13)/square-root-tau (50) < tau < 800 s) with a 160-mHz wide atomic resonance linewidth and a signal-to-noise ratio of 40 for each measurement cycle. Atomic resonance lines as narrow as 30 mHz on the 40.5GHz clock transition have been measured with no appreciable reduction in the ion signal. A stability of 7 x 10(-14)/square-root-tau is made possible by the signal to noise and line Q of this measured transition. Analysis of fundamental sources of frequency instability indicates that long term stability of 2 x 10(-16) is feasible for this device with existing technology for tau greater-than-or-equal-to 10(6) s. RP PRESTAGE, JD (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 13 TC 33 Z9 33 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 0018-9456 J9 IEEE T INSTRUM MEAS JI IEEE Trans. Instrum. Meas. PD APR PY 1991 VL 40 IS 2 BP 132 EP 136 DI 10.1109/TIM.1990.1032899 PG 5 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FN074 UT WOS:A1991FN07400015 ER PT J AU DICK, GJ WANG, RT AF DICK, GJ WANG, RT TI ULTRA-STABLE PERFORMANCE OF THE SUPERCONDUCTING CAVITY MASER SO IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT LA English DT Article AB Recent measurements on the superconducting cavity maser (SCM) oscillator show frequency stability of parts in 10(15) for times from 1 second to 1000 seconds. Phase noise of approximately -80dB/f3 was also measured. We believe this short- and mid-term performance to be better than that of any known microwave oscillator. In particular, stability at a measuring time of 1 second is 10 times better than that of a hydrogen maser, and phase noise at 8 GHz is more than 20 dB below that of the best multiplied quartz crystal oscillators. Substantial technical improvements have been made to eliminate frequency instability due to operational parameters. They are temperature, pump frequency, pump power, pump frequency polarization, temperature gradient, coupling strength and output VSWR. We have either stabilized the parameter or minimized the coefficient which couples the parameter to the operating frequency. A frequency pulling coil has been implemented and tested to enable the SCM to be slaved to a hydrogen maser with a time constant of approximately 50 seconds. This combination would allow the excellent long term performance of the hydrogen maser to be improved by the newly available short term performance of the SCM. RP DICK, GJ (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 7 TC 26 Z9 26 U1 1 U2 2 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9456 J9 IEEE T INSTRUM MEAS JI IEEE Trans. Instrum. Meas. PD APR PY 1991 VL 40 IS 2 BP 174 EP 177 DI 10.1109/TIM.1990.1032909 PG 4 WC Engineering, Electrical & Electronic; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FN074 UT WOS:A1991FN07400025 ER PT J AU BRUCKNER, J KORFER, M WANKE, H SCHROEDER, ANF FILGES, D DRAGOVITSCH, P ENGLERT, PAJ STARR, R TROMBKA, JI TAYLOR I DRAKE, DM SHUNK, ER AF BRUCKNER, J KORFER, M WANKE, H SCHROEDER, ANF FILGES, D DRAGOVITSCH, P ENGLERT, PAJ STARR, R TROMBKA, JI TAYLOR, I DRAKE, DM SHUNK, ER TI PROTON-INDUCED RADIATION-DAMAGE IN GERMANIUM DETECTORS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article ID FAST-NEUTRON DAMAGE; COAXIAL DETECTORS; SYSTEM AB High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10(8) protons cm-2 (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific as well as engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage the detectors were stepwise annealed at temperatures T less-than-or-equal-to 110-degrees-C while staying in their specially designed cryostats. This study shows that n-type HPGe detectors can be used in charged particle environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition. C1 PRINCETON GAMMA TECH, PRINCETON, NJ 08540 USA. UNIV COLOGNE, W-5000 COLOGNE 41, GERMANY. FORSCHUNGSZENTRUM JULICH, INST KERNPHYS, W-5170 JULICH 1, GERMANY. SAN JOSE STATE UNIV, SAN JOSE, CA 95192 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. CATHOLIC UNIV AMER, WASHINGTON, DC 20064 USA. UNIV CALIF LOS ALAMOS SCI LAB, LOS ALAMOS, NM 87545 USA. RP BRUCKNER, J (reprint author), MAX PLANCK INST CHEM, SAASTR 23, W-6500 MAINZ, GERMANY. NR 26 TC 27 Z9 27 U1 0 U2 4 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855 USA SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD APR PY 1991 VL 38 IS 2 BP 209 EP 217 DI 10.1109/23.289298 PG 9 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA FK173 UT WOS:A1991FK17300030 ER PT J AU VARNELL, LS CALLAS, JL MAHONEY, WA PEHL, RH LANDIS, DA LUKE, PN MADDEN, NW AF VARNELL, LS CALLAS, JL MAHONEY, WA PEHL, RH LANDIS, DA LUKE, PN MADDEN, NW TI SEGMENTED GE DETECTOR REJECTION OF INTERNAL BETA-ACTIVITY PRODUCED BY NEUTRON-IRRADIATION SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article AB Future Ge spectrometers flown in space to observe cosmic gamma-ray sources will incorporate segmented detectors to reduce the background from radioactivity produced by energetic particle reactions. To demonstrate the effectiveness of a segmented Ge detector in rejecting background events due to the beta decay of internal radioactivity, a laboratory experiment has been carried out in which radioactivity was produced in the detector by neutron irradiation. A Cf-252 source of neutrons was used to produce, by neutron capture on Ge-74 (36.5% of natural Ge) in the detector itself, Ge-75 (t1/2 = 82.78 min), which decays by beta emission with a maximum electron kinetic energy of 1188 keV. By requiring that an ionizing event deposit energy in two or more of the five segments of the detector, each about one centimeter thick, the beta particles, which have a range of about one millimeter, are rejected, while most external gamma rays incident on the detector are counted. Analysis of this experiment indicates that over 85% of the beta events from the decay of Ge-75 are rejected, in good agreement with Monte Carlo calculations. C1 UNIV CALIF BERKELEY LAWRENCE BERKELEY LAB,BERKELEY,CA 94720. RP VARNELL, LS (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 4 TC 1 Z9 3 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD APR PY 1991 VL 38 IS 2 BP 218 EP 220 DI 10.1109/23.289299 PN 1 PG 3 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA FK173 UT WOS:A1991FK17300031 ER PT J AU OWENS, A GEHRELS, N PASCARELLE, SM TEEGARDEN, BJ AF OWENS, A GEHRELS, N PASCARELLE, SM TEEGARDEN, BJ TI MONTE-CARLO CALCULATIONS OF GE DETECTOR ESCAPE-PEAK EFFICIENCIES SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article ID GE(LI) DETECTORS AB We present calculated first and second escape peak efficiencies for a variety of n-type coaxial Ge detectors using the Monte-Carlo method. The results are given for right-circular cylindrical geometries of size ranging from 3 cm diameter x 3 cm thick to 8 cm diameter x 8 cm thick. For completeness, we also list the intrinsic interaction and photopeak efficiencies for energies ranging from 20 keV to 20 MeV. The calculations have been tested against experimental measurement and found to be in agreement to within the quoted errors (typically 10%). It is found that the ratio of the second escape peak efficiency to the first escape peak efficiency, R, is approximately independent of energy for small detector volumes but has a weak power law energy dependence for large volumes. Finally, it is shown that R also varies as an inverse power law of the active volume. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. RP OWENS, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771, USA. RI Gehrels, Neil/D-2971-2012 NR 14 TC 5 Z9 5 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD APR PY 1991 VL 38 IS 2 BP 221 EP 225 DI 10.1109/23.289300 PN 1 PG 5 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA FK173 UT WOS:A1991FK17300032 ER PT J AU EDWARDS, HL NOLAN, PL HUGHES, EB LIN, YC KOCH, DG BERTSCH, DL FICHTEL, CE HARTMAN, RC HUNTER, SD KNIFFEN, DA THOMPSON, DJ KANBACH, G SOMMER, M SCHNEID, E HUGHLOCK, BW AF EDWARDS, HL NOLAN, PL HUGHES, EB LIN, YC KOCH, DG BERTSCH, DL FICHTEL, CE HARTMAN, RC HUNTER, SD KNIFFEN, DA THOMPSON, DJ KANBACH, G SOMMER, M SCHNEID, E HUGHLOCK, BW TI THE ESTIMATION OF BACKGROUND PRODUCTION BY COSMIC-RAYS IN HIGH-ENERGY GAMMA-RAY TELESCOPES SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article ID RADIATION; EMISSION AB A calculational method of estimating instrumental background in high energy gamma-ray telescopes, using the hadronic Monte Carlo code FLUKA87, is presented. The method is applied to the SAS-2 and EGRET telescope designs, and is also used to explore the level of background to be expected for alternative configurations of the proposed GRITS telescope, which adapts the external fuel tank of a Space Shuttle as a gamma-ray telescope with very large collecting area. Background produced in proton beam tests of EGRET is much less than the predicted level. This discrepancy appears to be due to the FLUKA87 inability to transport evaporation nucleons. We predict that the background in EGRET will be no more than 4-10% of the extragalactic diffuse gamma radiation. C1 STANFORD UNIV,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 14 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 APR PY 1991 VL 38 IS 2 BP 553 EP 558 DI 10.1109/23.289356 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA FK173 UT WOS:A1991FK17300089 ER PT J AU OWENS, A BAKER, R CLINE, TL GEHRELS, N JERMAKIAN, J NOLAN, T RAMATY, R SMITH, G STILWELL, DE TEEGARDEN, BJ TROMBKA, J YAVER, H CORK, CP LANDIS, DA LUKE, PN MADDEN, NW MALONE, D PEHL, RH HURLEY, K MATHIAS, S POST, AH AF OWENS, A BAKER, R CLINE, TL GEHRELS, N JERMAKIAN, J NOLAN, T RAMATY, R SMITH, G STILWELL, DE TEEGARDEN, BJ TROMBKA, J YAVER, H CORK, CP LANDIS, DA LUKE, PN MADDEN, NW MALONE, D PEHL, RH HURLEY, K MATHIAS, S POST, AH TI THE TRANSIENT GAMMA-RAY SPECTROMETER SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article ID SPECTROSCOPY AB We describe the Transient Gamma-Ray Spectrometer (TGRS) to be flown on board the WIND spacecraft. This instrument is designed to detect cosmic gamma-ray bursts over the energy range 20 keV to 10 MeV with an expected spectroscopic resolution of 2 keV at 1 MeV (E/DELTA-E = 500). The active detection element is a 215 cm3 high purity n-type Ge crystal cooled to cryogenic temperatures by a passive radiative cooler. The geometric field of view (FOV) defined by the cooler is 170-degrees FWFM. Burst data are stored directly in an on board 2.75 Mbit burst memory with an absolute timing accuracy of +/- 1.5 ms. This capacity is sufficient to store the entire spectral data set of all but the largest bursts. In addition to burst measurements, the instrument will also study solar flares, search for possible diffuse background lines and monitor the 511 keV positron annihilation radiation from the galactic center. The experiment is scheduled to be launched on a Delta II launch vehicle from Cape Canaveral on December 31, 1992. C1 UNIV CALIF BERKELEY LAWRENCE BERKELEY LAB, BERKELEY, CA 94702 USA. UNIV CALIF BERKELEY, SPACE SCI LAB, BERKELEY, CA 94720 USA. ARTHUR D LITTLE INC, CAMBRIDGE, MA 02140 USA. RP OWENS, A (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RI Gehrels, Neil/D-2971-2012 NR 9 TC 16 Z9 16 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 EI 1558-1578 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD APR PY 1991 VL 38 IS 2 BP 559 EP 567 DI 10.1109/23.289357 PN 1 PG 9 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA FK173 UT WOS:A1991FK17300090 ER PT J AU BOWER, CR DIETZ, KL RAMSEY, BD WEISSKOPF, MC AF BOWER, CR DIETZ, KL RAMSEY, BD WEISSKOPF, MC TI BACKGROUND IN X-RAY ASTRONOMY PROPORTIONAL-COUNTERS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article ID BALLOON AB We report the results of an investigation into the nature of background events in proportional counters sensitive to x-ray photons of energy < 150 keV. Even with the use of thick shields composed of high atomic number material, a significant flux background in the detector's energy region can result from multiple Compton scattering in the mass surrounding the active region of the detector. We emphasize the importance of the selection of detector components in the reduction of the background by more than an order of magnitude. Experimental results are shown to agree qualitatively with Monte Carlo simulations. RP BOWER, CR (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 7 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD APR PY 1991 VL 38 IS 2 BP 585 EP 590 DI 10.1109/23.289361 PN 1 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA FK173 UT WOS:A1991FK17300094 ER PT J AU EDMONDS, LD AF EDMONDS, LD TI A SIMPLE ESTIMATE OF FUNNELING-ASSISTED CHARGE COLLECTION SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article AB Funneling is qualitatively discussed in detail and a quantitative analysis is given for the total (time-integrated) collected charge. It is shown that for an n+/p junction, the total collected charge Q(T) is given by Q(T) = (1 + mu-n/mu-p)Q(D) + 2Q(diff) where Q(D) is the charge initially liberated in the depletion region and Q(diff) is charge collected by diffusion. This equation does not apply to very short ion tracks or to devices having a thin epilayer. RP EDMONDS, LD (reprint author), CALTECH, JET PROP LAB, MAILSTOP 303-220, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 8 TC 30 Z9 32 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9499 EI 1558-1578 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD APR PY 1991 VL 38 IS 2 BP 828 EP 833 DI 10.1109/23.289396 PN 2 PG 6 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA FK175 UT WOS:A1991FK17500004 ER PT J AU EDMONDS, LD AF EDMONDS, LD TI CHARGE COLLECTED BY DIFFUSION FROM AN ION TRACK UNDER MIXED BOUNDARY-CONDITIONS SO IEEE TRANSACTIONS ON NUCLEAR SCIENCE LA English DT Article AB Charge-carrier diffusion from an ion track in a silicon substrate, at least a few hundred mu-m thick, is analyzed. The substrate upper surface is treated as reflective except for a small section, intended to represent a reverse-biased junction, which is treated as a sink. Total charge collected by the sink is calculated by assuming transport to be governed by an ambipolar diffusion equation with temporally constant and spatially uniform carrier lifetime and diffusion coefficient. Present results apply to a normally incident track but could easily be generalized to arbitrary track direction. The collected charge is found to depend on track length and on the electrostatic capacitance, rather than the area, of the sink. Theoretical predictions are compared to the results of a numerical simulation called the Poisson and Continuity Equation Solver (PISCES) for three cases and are found to agree within a factor of two in the worst case. RP EDMONDS, LD (reprint author), CALTECH,JET PROP LAB,MAILSTOP 303-220,PASADENA,CA 91109, USA. NR 4 TC 9 Z9 9 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 0018-9499 J9 IEEE T NUCL SCI JI IEEE Trans. Nucl. Sci. PD APR PY 1991 VL 38 IS 2 BP 834 EP 837 DI 10.1109/23.289397 PN 2 PG 4 WC Engineering, Electrical & Electronic; Nuclear Science & Technology SC Engineering; Nuclear Science & Technology GA FK175 UT WOS:A1991FK17500005 ER PT J AU DEMELLO, LSH SANDERSON, AC AF DEMELLO, LSH SANDERSON, AC TI REPRESENTATIONS OF MECHANICAL ASSEMBLY SEQUENCES SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article AB This paper analyzes five representations of assembly sequences. These are based on directed graphs, on AND/OR graphs, on establishment conditions, and on precedence relationships. The latter includes two types: precedence relationships between the establishment of one connection between parts and the establishment of another connection, and precedence relationships between the establishment of one connection and states of the assembly process. The paper discusses how each representation is related to the others. The correctness and completeness of these representations are also addressed. The results presented are needed in the proof of correctness and completeness of algorithms for the generation of mechanical assembly sequences. C1 RENSSELAER POLYTECH INST,DEPT ELECT COMP & SYST ENGN,TROY,NY 12180. RP DEMELLO, LSH (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 9 TC 108 Z9 108 U1 1 U2 5 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 APR PY 1991 VL 7 IS 2 BP 211 EP 227 DI 10.1109/70.75904 PG 17 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA FB856 UT WOS:A1991FB85600003 ER PT J AU DEMELLO, LSH SANDERSON, AC AF DEMELLO, LSH SANDERSON, AC TI A CORRECT AND COMPLETE ALGORITHM FOR THE GENERATION OF MECHANICAL ASSEMBLY SEQUENCES SO IEEE TRANSACTIONS ON ROBOTICS AND AUTOMATION LA English DT Article AB This paper presents an algorithm for the generation of all mechanical assembly sequences for a given product. The algorithm employs a relational model of assemblies. In addition to the geometry of the assembly, this model includes a representation of the attachments that bind one part to another. The problem of generating the assembly sequences is transformed into the problem of generating disassembly sequences in which the dissassembly tasks are the inverse of feasible assembly tasks. This transformation leads to a decomposition approach in which the problem of disassembling one assembly is decomposed into distinct subproblems, each being to disassemble one subassembly. It is assumed that exactly two parts or subassemblies are joined at each time, and that whenever parts are joined forming a subassembly, all contacts between the parts in that subassembly are established. Furthermore, it is assumed that the feasibility of joining two subassemblies is independent of how those subassemblies were built. The algorithm returns the AND/OR graph representation of assembly sequences. The correctness of the algorithm is based on the assumption that it is always possible to decide correctly whether two subassemblies can be joined, based on geometrical and physical criteria. This paper presents an approach to compute this decision. An experimental implementation for the class of products made up of polyhedral and cylindrical parts having planar or cylindrical contacts among themselves is described. Bounds for the amount of computation involved are presented. C1 RENSSELAER POLYTECH INST,DEPT ELECT COMP & SYST ENGN,TROY,NY 12180. RP DEMELLO, LSH (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 26 TC 276 Z9 278 U1 2 U2 12 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 APR PY 1991 VL 7 IS 2 BP 228 EP 240 DI 10.1109/70.75905 PG 13 WC Automation & Control Systems; Engineering, Electrical & Electronic; Robotics SC Automation & Control Systems; Engineering; Robotics GA FB856 UT WOS:A1991FB85600004 ER PT J AU PITTMAN, JL BONHAUS, DL SICLARI, MJ DOLLYHIGH, SM AF PITTMAN, JL BONHAUS, DL SICLARI, MJ DOLLYHIGH, SM TI EULER ANALYSIS OF A HIGH-SPEED CIVIL TRANSPORT CONCEPT AT MACH-3 SO JOURNAL OF AIRCRAFT LA English DT Article AB A marching Euler solver, GEM3D, was used to predict the Mach 3 flowfield for the wing and body of a High-Speed Civil Transport (HSCT) concept. The analysis focused on a typical cruise lift coefficient of 0.1 at alpha = 3 deg. The Euler solution indicated that embedded shocks formed on the upper surface of the inboard wing panel and at the leading edge of the outboard wing panel caused by its supersonic leading-edge condition. According to a simple static-pressure criterion, the embedded wing upper-surface shocks were sufficiently strong to separate a turbulent boundary layer. Comparison of aerodynamic coefficients from the Euler solver with those from linear theory showed that the linear theory estimates of lift and drag were optimistic, which would lead to optimistic estimates of cruise range. RP PITTMAN, JL (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT MECH,AEROTHERMAL LOADS BRANCH,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 APR PY 1991 VL 28 IS 4 BP 239 EP 245 DI 10.2514/3.46018 PG 7 WC Engineering, Aerospace SC Engineering GA FQ806 UT WOS:A1991FQ80600003 ER PT J AU ADLER, RF HAKKARINEN, IM AF ADLER, RF HAKKARINEN, IM TI AIRCRAFT MULTIFREQUENCY PASSIVE MICROWAVE OBSERVATIONS OF LIGHT PRECIPITATION OVER THE OCEAN SO JOURNAL OF ATMOSPHERIC AND OCEANIC TECHNOLOGY LA English DT Article AB Aircraft passive microwave observations at 18, 37, 92, and 183 GHz of light oceanic precipitation are studied in conjunction with visible and infrared observations and ground-based radar data. Microwave signatures for clear, cloudy, and precipitating conditions are defined, with results in general agreement with previous theoretical results. Emission signatures are evident at 18, 37, and 92 GHz with clouds and precipitation producing an increase in brightness temperature (T(b)) over that observed over the low-emissivity ocean background. Polarization differences at 18 and 37 GHz also decrease in precipitation areas to minima of 30 K at 18 GHz and 15 K at 37 GHz. The 92-GHz T(b) shows a double-valued relationship, with an increase in cloudy and very lightly raining areas and a subsequent decrease for higher rain rates and deeper clouds where the ice scattering process becomes important. The 183-GHz observations display a distinct sensitivity to small amounts of ice. Simple channel differences are shown to compare favorable to the rain field, including polarization differences at 18 and 37 GHz and frequency differences between 92 and 37 GHz and between 183 and 92 GHz. The cases examined include both stratiform and convective structures, and the results indicate that this difference may be important in microwave T(b)-rain rate relationships. Some of the observed differences may be due to the presence or absence of a melting layer, observed as a radar "bright band." RP ADLER, RF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 912,GREENBELT,MD 20771, USA. NR 0 TC 9 Z9 9 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 APR PY 1991 VL 8 IS 2 BP 201 EP 220 DI 10.1175/1520-0426(1991)008<0201:AMPMOO>2.0.CO;2 PG 20 WC Engineering, Ocean; Meteorology & Atmospheric Sciences SC Engineering; Meteorology & Atmospheric Sciences GA FL197 UT WOS:A1991FL19700001 ER PT J AU RICE, JE TAYLOR, PR LEE, TJ ALMLOF, J AF RICE, JE TAYLOR, PR LEE, TJ ALMLOF, J TI THE DETERMINATION OF ACCURATE DIPOLE POLARIZABILITIES ALPHA AND GAMMA FOR THE NOBLE-GASES SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID GTO BASIS-SETS; MULTIPOLE POLARIZABILITIES; PERTURBATION-THEORY; SHIELDING FACTORS; 2ND-ROW ATOMS; HYPERPOLARIZABILITIES; DISPERSION; NEON; AR; SUSCEPTIBILITIES AB The static dipole polarizabilities alpha and gamma for the noble gases helium through xenon have been determined using large flexible one-particle basis sets in conjunction with high-level treatments of electron correlation. The electron correlation methods include single and double excitation coupled-cluster theory (CCSD), an extension of CCSD that includes a perturbational estimate of connected triple excitations, CCSD(T), and second-order perturbation theory (MP2). The computed alpha and gamma values are estimated to be accurate to within a few percent. Agreement with experimental data for the static hyperpolarizability gamma is good for neon and xenon, but for argon and krypton the differences are larger than the combined theoretical and experimental uncertainties. Based on our calculations, we suggest that the experimental value of gamma for argon is too low. Adjusting this value would also bring the experimental value of gamma for krypton into better agreement with our computed result. The MP2 values for the polarizabilities of neon, argon, krypton, and xenon are in reasonable agreement with the CCSD and CCSD(T) values, suggesting that this less expensive method may be useful in studies of polarizabilities for larger systems. C1 ELORET INST,PALO ALTO,CA 94303. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV MINNESOTA,MINNESOTA SUPERCOMP INST,MINNEAPOLIS,MN 55455. UNIV MINNESOTA,DEPT CHEM,MINNEAPOLIS,MN 55455. RP RICE, JE (reprint author), IBM CORP,ALMADEN RES CTR,DIV RES,SAN JOSE,CA 95120, USA. RI Rice, Julia/K-4928-2012; Lee, Timothy/K-2838-2012 OI Rice, Julia/0000-0001-5059-5127; NR 30 TC 106 Z9 106 U1 0 U2 6 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 APR 1 PY 1991 VL 94 IS 7 BP 4972 EP 4979 DI 10.1063/1.460533 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FF820 UT WOS:A1991FF82000029 ER PT J AU CHOU, MD KRATZ, DP RIDGWAY, W AF CHOU, MD KRATZ, DP RIDGWAY, W TI INFRARED RADIATION PARAMETERIZATIONS IN NUMERICAL CLIMATE MODELS SO JOURNAL OF CLIMATE LA English DT Article AB Parameterizations for infrared radiation (IR) in clear atmospheres can be made fast and accurate by grouping spectral regions with similar radiative properties, and by separating the low pressure region of the atmosphere from the high pressure region. Various approaches are presented in this study to parameterizing the broadband transmission functions for use in numerical climate models. For water vapor and carbon dioxide (CO2) bands, the transmission functions are parameterized separately for the middle atmosphere (0.01-30 mb) and for the region below. In the middle atmosphere where the dependence of absorption on pressure and temperature is not strong, the diffuse transmission functions are derived from that at a reference pressure and temperature. In the lower stratosphere and the troposphere, the spectra are grouped into band-center regions and band-wing regions. One-parameter scaling is applied to approximate a nonhomogeneous path with an equivalent homogeneous path, and the diffuse transmittances are either fit by analytical functions or interpolated from precomputed tables. As opposed to the one-parameter scaling, which applies only to a relatively narrow pressure range, the two-parameter scaling (commonly called the Curtis-Godson approximation) is applied to parameterizing the carbon dioxide (CO2) and ozone (O3) transmission functions in both the middle and the lower atmosphere. The diffuse transmission functions are simply interpolated from three small precomputed tables. The accuracies of cooling rates in the 15-mu-m band computed using the approximation for both the middle and the lower atmospheres are comparable with that using the parameterizations separately for the middle and the lower atmospheres. The radiative effect of nitrous oxide (N2O) and methane (CH4) is also examined. Parameterizations are presented for the N2O and CH4 diffuse transmission functions. RP CHOU, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 0 TC 136 Z9 142 U1 1 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD APR PY 1991 VL 4 IS 4 BP 424 EP 437 DI 10.1175/1520-0442(1991)004<0424:IRPINC>2.0.CO;2 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FK290 UT WOS:A1991FK29000005 ER PT J AU JIMENEZ, J MOIN, P AF JIMENEZ, J MOIN, P TI THE MINIMAL FLOW UNIT IN NEAR-WALL TURBULENCE SO JOURNAL OF FLUID MECHANICS LA English DT Article ID CHANNEL FLOW; BOUNDARY-LAYER; STREAMWISE VORTICES; REYNOLDS-NUMBER; REGION AB Direct numerical simulations of unsteady channel flow were performed at low to at low at moderate Reynolds numbers on computational boxes chosen small enough so that the flow consists of a doubly periodic (in x and z) array of identical structures. The goal is to isolate the basic flow unit, to study its morphology and dynamics, and to evaluate its contribution to turbulence in fully developed channels. For boxes wider than approximately 100 wall units in the spanwise direction, the flow is turbulent and the low-order turbulence statistics are in good agreement with experiments in the near-wall region. For a narrow range of widths below that threshold, the flow near only one wall remains turbulent, but it statistics are still in fairly good agreement with experimental data when scaled with the local wall stress. For narrower boxes only laminar solutions are found. In all cases, the elementary box contains a single low-velocity streak, consisting of a longitudinal strip on which a thin layer of spanwise vorticity is lifted away from the wall. A fundamental period of intermittency for the regeneration of turbulence is identified, and that process is observed to consist of the wrapping of the wall-layer vorticity around a single inclined longitudinal vortex. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV POLITECN MADRID,SCH AERONAUT,MADRID,SPAIN. RP JIMENEZ, J (reprint author), STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305, USA. RI jimenez, javier/A-6691-2008 OI jimenez, javier/0000-0003-0755-843X NR 27 TC 466 Z9 471 U1 4 U2 46 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 APR PY 1991 VL 225 BP 213 EP 240 DI 10.1017/S0022112091002033 PG 28 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FK161 UT WOS:A1991FK16100009 ER PT J AU ABARBANEL, SS DON, WS GOTTLIEB, D RUDY, DH TOWNSEND, JC AF ABARBANEL, SS DON, WS GOTTLIEB, D RUDY, DH TOWNSEND, JC TI SECONDARY FREQUENCIES IN THE WAKE OF A CIRCULAR-CYLINDER WITH VORTEX SHEDDING SO JOURNAL OF FLUID MECHANICS LA English DT Article AB A detailed numerical study of two-dimensional flow past a circular cylinder at moderately low Reynolds numbers has been conducted using three different numerical algorithms for solving the time-dependent compressible Navier-Stokes equations. It was found that if the algorithm and associated boundary conditions were consistent and stable, then the major features of the unsteady wake were well predicted. However, it was also found that even stable and consistent boundary conditions could introduce additional periodic phenomena reminiscent of the type seen in previous wind-tunnel experiments. However, these additional frequencies were eliminated by formulating the boundary conditions in terms of the characteristic variables. An analysis based on a simplified model provides an explanation for this behaviour. C1 BROWN UNIV,PROVIDENCE,RI 02912. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP ABARBANEL, SS (reprint author), TEL AVIV UNIV,IL-69978 TEL AVIV,ISRAEL. RI Don, Wai Sun/B-7194-2009; HKBU, Mathematics/B-5086-2009 NR 16 TC 24 Z9 24 U1 0 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 APR PY 1991 VL 225 BP 557 EP 574 DI 10.1017/S0022112091002173 PG 18 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FK161 UT WOS:A1991FK16100023 ER PT J AU MATTHAEUS, WH KLEIN, LW GHOSH, S BROWN, MR AF MATTHAEUS, WH KLEIN, LW GHOSH, S BROWN, MR TI NEARLY INCOMPRESSIBLE MAGNETOHYDRODYNAMICS, PSEUDOSOUND, AND SOLAR-WIND FLUCTUATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID TURBULENCE; EVOLUTION; SPECTRA; FLOWS AB Recent theoretical studies have led to an improvement of our understanding of the behavior of a compressible magnetofluid with an adiabatic equation of state, in the limit of low plasma frame Mach number. Under certain assumptions the lowest-order behavior is that of incompressible magnetohydrodynamics (MHD), associated with small nonpropagating "pseudosound" density fluctuations. Departures from incompressibility include magnetoacoustic fluctuations, appearing at the same order as the pseudosound. In the present paper the simplest nearly incompressible MHD theory, with a polytropic equation of state, is reviewed, with an emphasis on observable consequences, particularly for solar wind turbulence. A central feature of the theory is the development of a relationship between the spectra of density fluctuations and of magnetic and velocity fluctuations. Here this relationship is extended to include uniform magnetic field effects, the possibility of anisotropic turbulence, and the influences of magnetic and cross helicities. Consequences of the theory, including Mach number scalings of density fluctuations and their wave number dependence, the anticorrelation of mechanical and magnetic pressure, and the reduction of density fluctuations in Alfvenic periods, are discussed in terms of Voyager solar wind observations. Finally, we present results of a simulation using a two-dimensional compressible MHD code that illustrate the appearance of similar anticorrelations. C1 APPL RES CORP,LANDOVER,MD 20895. NASA,GODDARD SPACE FLIGHT CTR,USRA,GREENBELT,MD 20771. CALTECH,DEPT PHYS,PASADENA,CA 91125. RP MATTHAEUS, WH (reprint author), UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19716, USA. NR 40 TC 87 Z9 87 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 APR 1 PY 1991 VL 96 IS A4 BP 5421 EP 5435 DI 10.1029/90JA02609 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF828 UT WOS:A1991FF82800004 ER PT J AU ZHAO, XP OGILVIE, KW WHANG, YC AF ZHAO, XP OGILVIE, KW WHANG, YC TI MODELING THE EFFECTS OF FAST SHOCKS ON SOLAR-WIND MINOR IONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID NONCOPLANAR MAGNETIC-FIELDS; EARTHS BOW SHOCK; SLOW SHOCKS; MAGNETOSHEATH; COLLISIONLESS; VELOCITY; HELIUM AB Observations show that when alpha particles and other minor ions in the solar wind plasma encounter fast shocks they are heated more than protons and their bulk motion is decelerated less than protons. These effects have been studied using a three-fluid model, and the model predictions have been compared with observations. The comparison indicates that for supercritical fast shocks the three-fluid model can explain cross-shock minor ion heating which is significantly greater than that of protons. When the ratio of specific heats for minor ions, gamma-alpha, equals 2, both the lesser cross-shock deceleration and the greater heating of minor ions than of protons can be predicted by the model; thus the minor ion heating through the shock transition region is consistent with the involvement of 2 degrees of freedom. Because the analysis is formulated in the de Hoffmann-Teller frame of reference, the method is not valid for perpendicular shocks or when the angle is large. These results agree with the few extant observations and might be confirmed by further observations at the Earth's bow shock. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. CATHOLIC UNIV AMER,DEPT MECH ENGN,WASHINGTON,DC 20064. RP ZHAO, XP (reprint author), STANFORD UNIV,CTR SPACE SCI & ASTROPHYS,ERL 329,STANFORD,CA 94305, USA. NR 32 TC 13 Z9 14 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 APR 1 PY 1991 VL 96 IS A4 BP 5437 EP 5445 DI 10.1029/90JA02753 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF828 UT WOS:A1991FF82800005 ER PT J AU HOEGY, WR GREBOWSKY, JM AF HOEGY, WR GREBOWSKY, JM TI DEPENDENCE OF POLAR HOLE DENSITY ON MAGNETIC AND SOLAR CONDITIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ATMOSPHERE EXPLORER-C; WINTER F-REGION; IONOSPHERE AB The dependence of electron density in the polar F region ionization hole on solar activity, universal time (UT), magnetic activity, season, and hemisphere is studied using data from the Langmuir probes on Atmosphere Explorer C and Dynamics Explorer 2. The AE-C data were obtained during solar minimum when the 3-month average 10.7-cm solar flux index varied from 70 to 140; the DE 2 data were obtained near solar maximum when the 10.7-cm solar flux index varied from 120 to 220. The polar hole is a region on the nightside of the polar cap where reduced ionization exists because of the long transport time of ionization from the dayside across the polar cap. The behavior of this region as a function of 10.7-cm solar flux (F10.7), UT, and Kp is statistically modeled for equinox, summer, and winter conditions for each hemisphere separately. The strongest dependencies are observed in F10.7 and UT; the Kp dependence is weak because it poorly represents the complexities of convection across the polar cap. A strong hemispherical difference due to the offset of the magnetic poles from the Earth's rotation axis is observed in the UT dependence of the ionization hole: there is a density minimum at about 20.3 hours UT in the south and at about 4.8 hours UT in the north; the minimum to maximum UT density variation is about a factor of 8.9 in the south and about a factor of 2.1 in the north. There is a seasonal variation in the dependence of ion density (N(i)) on solar flux (F10.7). Use of the relationship (N(i) approximately F10.7D yields values of D of approximately unity (1.) in the summer polar hole and about 2.1 during equinox. There is an overall asymmetry in the density level between hemispheres; it was found that the winter hole density is about a factor of 10 greater in the north than in the south. The Utah State University time dependent ionosphere model gives similar UT behavior to that found in the AE-C and DE 2 data. RP HOEGY, WR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 914,GREENBELT,MD 20771, USA. RI Grebowsky, Joseph/I-7185-2013 NR 21 TC 7 Z9 7 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 APR 1 PY 1991 VL 96 IS A4 BP 5737 EP 5755 DI 10.1029/90JA02755 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF828 UT WOS:A1991FF82800029 ER PT J AU BURLAGA, LF AF BURLAGA, LF TI INTERMITTENT TURBULENCE IN THE SOLAR-WIND SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD; GENERALIZED DIMENSIONS; STRANGE ATTRACTORS; FLUCTUATIONS; NUMBER AB This paper demonstrates the existence of intermittent turbulence in the solar wind at 8.5 AU. The pth-order velocity structure functions show scaling behavior in the range of periods from 0.85 hour to 13.6 hours for p less-than-or-equal-to 20. The exponent of the scaling law s(p) is a quadratic function of p. Our observations of s(p) for compressible MHD turbulence on a scale of the order of approximately 1 AU = 1.5 x 10(8) km are consistent with laboratory measurements of s(p) for gasdynamic turbulence on a scale of the order of 1 m, indicating the universal character of intermittent turbulence. The observations are not described by the "constant beta" model of intermittent turbulence. They are marginally consistent with the lognormal model. The observations are consistent with a random beta model prediction which assumes that the turbulence is a mixture of sheets and space-filling eddies. RP BURLAGA, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 29 TC 174 Z9 175 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD APR 1 PY 1991 VL 96 IS A4 BP 5847 EP 5851 DI 10.1029/91JA00087 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF828 UT WOS:A1991FF82800038 ER PT J AU WOLFENDEN, A LASTRAPES, G DUGGAN, MB RAJ, SV AF WOLFENDEN, A LASTRAPES, G DUGGAN, MB RAJ, SV TI TEMPERATURE-DEPENDENCE OF THE ELASTIC-MODULI AND DAMPING FOR POLYCRYSTALLINE LIF-22-PERCENT CAF2 EUTECTIC SALT SO JOURNAL OF MATERIALS SCIENCE LA English DT Article AB The Young's and shear moduli and damping were measured for as-cast polycrystalline LiF-22 (mol %) CaF2 eutectic specimens as a function of temperature using the piezoelectric ultrasonic composite oscillator technique (PUCOT). The shear modulus decreased with increasing temperature from about 40 GPa at 295 K to about 30 GPa at 1000 K, while the Young's modulus decreased from about 115 GPa at 295 K to about 35 GPa at 900 K. These values are compared with those derived from the rule of mixtures using elastic moduli data for LiF and CaF2 single crystals. It is shown that, while the shear modulus data agree reasonably well with the predicted trend, there is a large discrepancy between the theoretical calculations and the Young's modulus values, where this disagreement increases with increasing temperature. The reason for this discrepancy is unclear but several possibilities are examined and discussed. The effective activation energy for damping was determined to be about 0.21 eV/atom which was found to be in reasonable agreement with the activation energy for migration of anion vacancies in the CaF2 phase. C1 TEXAS A&M UNIV SYST,ADV MAT LAB,COLLEGE STN,TX 77843. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP WOLFENDEN, A (reprint author), TEXAS A&M UNIV SYST,DEPT MECH ENGN,COLLEGE STN,TX 77843, USA. NR 38 TC 3 Z9 3 U1 1 U2 3 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD APR 1 PY 1991 VL 26 IS 7 BP 1793 EP 1798 DI 10.1007/BF00543604 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA FG081 UT WOS:A1991FG08100012 ER PT J AU OBERBECK, VR MARSHALL, J SHEN, T AF OBERBECK, VR MARSHALL, J SHEN, T TI PREBIOTIC CHEMISTRY IN CLOUDS SO JOURNAL OF MOLECULAR EVOLUTION LA English DT Article DE PREBIOTIC CHEMISTRY; PRIMORDIAL SOUP; OPARIN HYPOTHESIS; EVOLUTION; IMPACT CATASTROPHISM ID CHEMICAL EVOLUTION; EARLY EARTH; ORIGIN; ATMOSPHERE; LIFE; HYPOTHESIS; OCEAN; MOON AB In the traditional concept for the origin of life as proposed by Oparin and Haldane in the 1920s, prebiotic reactants became slowly concentrated in the primordial oceans and life evolved slowly from a series of highly protracted chemical reactions during the first billion years of Earth's history. However, chemical evolution may not have occurred continuously because planetesimals and asteroids impacted the Earth many times during the first billion years, may have sterilized the Earth, and required the process to start over. A rapid process of chemical evolution may have been required in order that life appeared at or before 3.5 billion years ago. Thus, a setting favoring rapid chemical evolution may be required. A chemical evolution hypothesis set forth by Woese in 1979 accomplished prebiotic reactions rapidly in droplets in giant atmospheric reflux columns. However, in 1985 Scherer raised a number of objections to Woese's hypothesis and concluded that it was not valid. We propose a mechanism for prebiotic chemistry in clouds that satisfies Scherer's concerns regarding the Woese hypothesis and includes advantageous droplet chemistry. Prebiotic reactants were supplied to the atmosphere by comets, meteorites, and interplanetary dust or synthesized in the atmosphere from simple compounds using energy sources such as ultraviolet light, corona discharge, or lightning. These prebiotic monomers would have first encountered moisture in cloud drops and precipitation. We propose that rapid prebiotic chemical evolution was facilitated on the primordial Earth by cycles of condensation and evaporation of cloud drops containing clay condensation nuclei and nonvolatile monomers. For example, amino acids supplied by, or synthesized during entry of, meteorites, comets, and interplanetary dust would have been scavenged by cloud drops containing clay condensation nuclei. Polymerization would have occurred within cloud systems during cycles of condensation, freezing, melting, and evaporation of cloud drops. We suggest that polymerization reactions occurred in the atmosphere as in the Woese hypothesis, but life originated in the ocean as in the Oparin-Haldane hypothesis. The rapidity with which chemical evolution could have occurred within clouds accommodates the time constraints suggested by recent astrophysical theories. C1 ARIZONA STATE UNIV,TEMPE,AZ 85287. SETI INST,MOFFETT FIELD,CA 94035. RP OBERBECK, VR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 35 TC 11 Z9 11 U1 6 U2 17 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0022-2844 J9 J MOL EVOL JI J. Mol. Evol. PD APR PY 1991 VL 32 IS 4 BP 296 EP 303 DI 10.1007/BF02102187 PG 8 WC Biochemistry & Molecular Biology; Evolutionary Biology; Genetics & Heredity SC Biochemistry & Molecular Biology; Evolutionary Biology; Genetics & Heredity GA FF217 UT WOS:A1991FF21700006 PM 11538260 ER PT J AU CHANCE, KV JENNINGS, DA EVENSON, KM VANEK, MD NOLT, IG RADOSTITZ, JV PARK, K AF CHANCE, KV JENNINGS, DA EVENSON, KM VANEK, MD NOLT, IG RADOSTITZ, JV PARK, K TI PRESSURE BROADENING OF THE 118.455 CM-1 ROTATIONAL LINES OF OH BY H-2, HE, N2, AND O2 SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID BEAM ELECTRIC RESONANCE; HYDROXYL; SPECTRUM; SPECTROSCOPY; TRANSITIONS; OD; CO C1 NATL INST STAND & TECHNOL,WASHINGTON,DC. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. UNIV OREGON,DEPT PHYS,EUGENE,OR 97403. RP CHANCE, KV (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138, USA. OI Chance, Kelly/0000-0002-7339-7577 NR 20 TC 40 Z9 40 U1 1 U2 4 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 APR PY 1991 VL 146 IS 2 BP 375 EP 380 DI 10.1016/0022-2852(91)90012-Y PG 6 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FD466 UT WOS:A1991FD46600012 ER PT J AU HILLMAN, JJ JENNINGS, DE HALSEY, GW NADLER, S BLASS, WE AF HILLMAN, JJ JENNINGS, DE HALSEY, GW NADLER, S BLASS, WE TI AN INFRARED STUDY OF THE BENDING REGION OF ACETYLENE SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID SATURNIAN SYSTEM; C-12-C-13 RATIO; JUPITER; SPECTRUM; IDENTIFICATION; ATMOSPHERE; ETHANE; CM-1; C2H2; NH3 C1 UNIV TENNESSEE,DEPT PHYS & ASTRON,KNOXVILLE,TN 37996. RP HILLMAN, JJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Blass, William/A-2792-2008; Jennings, Donald/D-7978-2012 NR 37 TC 37 Z9 39 U1 2 U2 7 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 APR PY 1991 VL 146 IS 2 BP 389 EP 401 DI 10.1016/0022-2852(91)90014-2 PG 13 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA FD466 UT WOS:A1991FD46600014 ER PT J AU MIELE, A WANG, T DEATON, AW AF MIELE, A WANG, T DEATON, AW TI PROPERTIES OF THE OPTIMAL TRAJECTORIES FOR COPLANAR, AEROASSISTED ORBITAL TRANSFER SO JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS LA English DT Article DE FLIGHT MECHANICS; ASTRODYNAMICS; AEROASSISTED ORBITAL TRANSFER; OPTIMAL TRAJECTORIES; NONLINEAR 2-POINT BOUNDARY-VALUE PROBLEMS; SEQUENTIAL GRADIENT-RESTORATION ALGORITHM ID GRADIENT-RESTORATION ALGORITHMS; GUIDANCE AB This paper is concerned with the optimization of trajectories for coplanar, aeroassisted orbital transfer (AOT) from a high Earth orbit (HEO) to a low Earth orbit (LEO). In particular, HEO can be a geosynchronous Earth orbit (GEO). It is assumed that the initial and final orbits are circular, that the gravitational field is central and is governed by the inverse square law, and that two impulses are employed, one at HEO exit and one at LEO entry. During the atmospheric pass, the trajectory is controlled via the lift coefficient in such a way that the total characteristic velocity is minimized. First, an ideal optimal trajectory is determined analytically for lift coefficient unbounded. This trajectory is called grazing trajectory, because the atmospheric pass is made by flying at constant altitude along the edge of the atmosphere until the excess velocity is depleted. For the grazing trajectory, the lift coefficient varies in such a way that the lift, the centrifugal force due to the Earth's curvature, the weight, and the Coriolis force due to the Earth's rotation are in static balance. Also, the grazing trajectory minimizes the total characteristic velocity and simultaneously nearly minimizes the peak values of the altitude drop, the dynamic pressure, and the heating rate. Next, starting from the grazing trajectory results, a real optimal trajectory is determined numerically for lift coefficient bounded from both below and above. This trajectory is characterized by atmospheric penetration with the smallest possible entry angle, followed by flight at the lift coefficient lower bound. Consistently with the grazing trajectory behavior, the real optimal trajectory minimizes the total characteristic velocity and simultaneously nearly minimizes the peak values of the altitude drop, the dynamic pressure, and the heating rate. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SYST ANAL & INTEGRAT LAB,FLIGHT MECH BRANCH,HUNTSVILLE,AL 35812. RP MIELE, A (reprint author), RICE UNIV,AERO ASTRONAUT GRP,HOUSTON,TX 77251, USA. NR 18 TC 8 Z9 9 U1 1 U2 3 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0022-3239 J9 J OPTIMIZ THEORY APP JI J. Optim. Theory Appl. PD APR PY 1991 VL 69 IS 1 BP 1 EP 30 DI 10.1007/BF00940459 PG 30 WC Operations Research & Management Science; Mathematics, Applied SC Operations Research & Management Science; Mathematics GA FL717 UT WOS:A1991FL71700001 ER PT J AU LIN, A AF LIN, A TI PARALLEL ALGORITHMS FOR BOUNDARY-VALUE-PROBLEMS SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article ID SCHEMES C1 NASA,LEWIS RES CTR,INST COMPUTAT MECH PROPULT,CLEVELAND,OH 44135. RP LIN, A (reprint author), UNIV PENN,DEPT MECH ENGN & APPL MECH,PHILADELPHIA,PA 19104, USA. NR 20 TC 0 Z9 0 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD APR PY 1991 VL 11 IS 4 BP 284 EP 290 DI 10.1016/0743-7315(91)90035-8 PG 7 WC Computer Science, Theory & Methods SC Computer Science GA FD772 UT WOS:A1991FD77200003 ER PT J AU THY, P LOFGREN, GE IMSLAND, P AF THY, P LOFGREN, GE IMSLAND, P TI MELTING RELATIONS AND THE EVOLUTION OF THE JAN-MAYEN MAGMA SYSTEM SO JOURNAL OF PETROLOGY LA English DT Article ID TRACE-ELEMENT VARIATIONS; EXPERIMENTAL PETROLOGY; FRACTURE-ZONE; EXPERIMENTAL CONSTRAINTS; PHASE-RELATIONS; MID-ATLANTIC; 1 ATM; BASALTS; RIDGE; FRACTIONATION AB The island of Jan Mayen is composed of a potassic alkalic volcanic rock suite including ankaramite, basalt, tristanite, and trachyte lavas. Two basaltic samples with 9.9 and 4.5 wt.% MgO, respectively, were melted in a series of experiments at 1 atm pressure, at temperatures from above the liquidus to near the solidus, and at f(O2) near that of the fayalite-magnetite-quartz oxygen buffer. The main purpose was to model the low-pressure evolution of the Jan Mayen magma system. The high-MgO sample crystallized olivine from 1278-degrees-C, plagioclase from 1180-degrees-C, and augite from 1172-degrees-C. Chromite was present throughout the melting interval. The liquid compositions were in accord with the crystalline assemblages;Al2O3 and CaO decreased with the appearance of plagioclase and augite at approximately 7 wt.% MgO. SiO2 increased slightly throughout the melting interval. The low-MgO sample crystallized plagioclase from 1188-degrees-C, olivine from 1143-degrees-C; and augite from 1122-degrees-C. Ilmenite and magnetite appeared simultaneously at approximately 1105-degrees-C. The liquid line of descent for this sample was strongly influenced by the crystallization of Fe-Ti oxides when MgO reached 3-3.5 wt.%. After the appearance of Fe-Ti oxides, Al2O3 and SiO2 showed a marked increase whereas FeO and TiO2 decreased. Because of the small size of the low-temperature liquid regions, the liquid lines of descent could not be traced below 60-70% crystallization. In terms of a pseudo-quaternary phase diagram, the liquid line of descent for the high-MgO sample moves toward more nepheline-normative compositions crystallizing approximately equalamounts, by weight, of olivine, plagioclase, and augite. The crystallizing augites are slightly nepheline-normative. For the low-MgO sample, there is a strong increase in SiO2 with the appearance of Fe-Ti oxide minerals; however, this effect is insufficient to cause the liquids to evolve toward quartz-normative compositions. Comparison of the experimentally produced liquids with the natural rock chemistry points to a relatively early crystallization of augite and Fe-Ti oxides and a relatively late appearance of plagioclase for the Jan Mayen lavas. This suggest that the Jan Mayen magma system evolved under relatively high P(H2O), essentially by crystallizing augite and olivine until 4-5 wt.% MgO, where plagioclase and Fe-Ti oxides appear. Plagioclase is present in small amounts in the alkalic basalts, but fractionation of this phase is not required to explain the chemical variation. It is also significant that the majority of the alkalic basalts on pseudo-quaternary diagrams plot in an area where, at any pressure, the liquid is not saturated in plagioclase. Because the natural lavas evolve toward increasing normative-nepheline content, it is implied that the quartz-normative tristanites and trachytes are unrelated to the alkalic basalts. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV ICELAND,NORDIC VOLCANOL INST,IS-101 REYKJAVIK,ICELAND. NR 50 TC 31 Z9 31 U1 0 U2 6 PU OXFORD UNIV PRESS UNITED KINGDOM PI OXFORD PA WALTON ST JOURNALS DEPT, OXFORD, ENGLAND OX2 6DP SN 0022-3530 J9 J PETROL JI J. Petrol. PD APR PY 1991 VL 32 IS 2 BP 303 EP 332 PG 30 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FK143 UT WOS:A1991FK14300003 ER PT J AU BEARD, JS LOFGREN, GE AF BEARD, JS LOFGREN, GE TI DEHYDRATION MELTING AND WATER-SATURATED MELTING OF BASALTIC AND ANDESITIC GREENSTONES AND AMPHIBOLITES AT 1, 3, AND 6.9KB SO JOURNAL OF PETROLOGY LA English DT Article ID = 5 KB; PHASE-RELATIONS; ISLAND-ARC; STABILITY RELATIONS; VOLCANIC-ROCKS; 8 KBAR; HORNBLENDE; SYSTEM; CRYSTALLIZATION; ANATEXIS AB The melting relations of five metamorphosed basalts and andesites (greenstones and amphibolites), collected from the late Jurassic Smartville arc complex of California, were investigated experimentally at 800-1000-degrees-C and 1, 3, and 6.9 kb. Dehydration-melting (no water added) experiments contained only the water structurally bound in metamorphic minerals (largely amphiboles). They yielded mildly peraluminous to metaluminous granodioritic to trondhjemitic melts (Na/K is a function of starting composition) similar in major element composition to silicic rocks in modern oceanic arcs. The dehydration melts are water-undersaturated, with P(H2O) < 1 kb, and coexist with the anhydrous residual solid (restite) assemblage plagioclase + orthopyroxene + clinopyroxene + magnetite +/- ilmenite, with plagioclase constituting approximately 50% of the restite mode. In the dehydration-melting experiments at 3 kb the onset of melting occurred between 850 and 900-degrees-C, as amphibole and quartz broke down to yield pyroxenes plus melt. Total pressure is greater than P(H2O) in the dehydration-melting experiments and has little effect on melt composition or phase relations. In the water-saturated (water added, so that P(H2O) = P(total)) experiments, melts formed at 3 kb and above are strongly peraluminous, rich in Ca and poor in Fe, Mg, Ti, and K. Their compositions are unlike those of most silicic igneous rocks. These melts coexist with the amphibole-rich, plagioclase-poor restite assemblage amphibole + magnetite +/- clinopyroxene +/- plagioclase +/- ilmenite. The highly aluminous nature of the melts and the plagioclase-poor nature of the restite both reflect the substantial contribution of plagioclase (along with quartz) to melts in high-pressure water-saturated systems. Water pressure equals P(total) in the water-saturated experiments and has a profound effect on both melt composition and phase relations. At 1 kb, the water-saturated experiments yielded melt and mineral products with some characteristics of the dehydration-melting experiments (no amphibole at high T), and some characteristics of the 3-kb, water-saturated experiments (amphibole plus melt coexisting at lower T, elevated Al, lowered Fe). As pressure is increased from 3 to 6.9 kb, the stability fields of both plagioclase and clinopyroxene decreased relative to amphibole and the Al contents of the melts increase. These experiments have important implications for the petrogenesis of low-K silicic rocks in arcs. First, dehydration melting is a viable mechanism for the formation of these rocks; water-saturated melting is not. Second, because of the influence of rock composition on melt composition, low-grade metamorphic and hydrothermal processes that alter the alkali contents and Na/K in arc basement terranes may have a direct impact on the petrogenesis of silicic magmas in arcs, particularly the formation of extremely low-K trondhjemites. Third, the experiments predict that anhydrous pyroxene- and plagioclase-rich 'granulitic' restite assemblages should develop as a result of partial melting in arc terranes. Such assemblages occur in at least two deeply eroded arc complexes. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 58 TC 663 Z9 714 U1 10 U2 51 PU OXFORD UNIV PRESS UNITED KINGDOM PI OXFORD PA WALTON ST JOURNALS DEPT, OXFORD, ENGLAND OX2 6DP SN 0022-3530 J9 J PETROL JI J. Petrol. PD APR PY 1991 VL 32 IS 2 BP 365 EP 401 PG 37 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FK143 UT WOS:A1991FK14300005 ER PT J AU ZLOTNICKI, V AF ZLOTNICKI, V TI SEA-LEVEL DIFFERENCES ACROSS THE GULF-STREAM AND KUROSHIO EXTENSION SO JOURNAL OF PHYSICAL OCEANOGRAPHY LA English DT Article ID NORTH-ATLANTIC; SEASONAL VARIABILITY; SATELLITE ALTIMETRY; FLORIDA CURRENT; DYNAMIC TOPOGRAPHY; CAPE HATTERAS; HEAT-STORAGE; WORLD OCEAN; CIRCULATION; TRANSPORT AB Geosat altimetric data for November 1986 to December 1988 are used to estimate sea level differences between the Sargasso Sea and the slope waters across the Gulf Stream region, averaged between 73-degrees and 61-degrees-W, and comparable areas across the Kuroshio extension region, averaged between 143-degrees and 156-degrees-E. Sea level differences (south minus north) in both regions are higher in the fall. Their projection onto an annual cosine peaks in late September-mid-October, with 9 cm (Gulf Stream region) and 6.9 cm (Kuroshio region) amplitudes, and accounts for about 60% of the variance. Residual altimetric errors due to water vapor, orbit, and sea state bias are shown to be minor or negligible contributors, as is uncertainty in the atmospheric pressure used in the inverse barometer correction and uncertainty in the tidal model removed. Ship drift data averaged in a comparable manner appear to respond to time changes in Ekman transport rather than the geostrophic transport measured by the sea level differences. Dynamic heights above 200 m computed from climatological (1940-75) water temperature and salinity data show that, while dynamic heights in both regions rise by 6 to 7 cm in September due to heating above the seasonal thermocline, the south-north difference in dynamic height has a somewhat different seasonal pattern: in the Gulf Stream region the annual cycle of climatological differential dynamic heights (south minus north) accounts for 86% of the variance, has 3 dyn cm amplitude and peaks in late November; in the Kuroshio region it is negligible. RP ZLOTNICKI, V (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 49 TC 42 Z9 42 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 APR PY 1991 VL 21 IS 4 BP 599 EP 609 DI 10.1175/1520-0485(1991)021<0599:SLDATG>2.0.CO;2 PG 11 WC Oceanography SC Oceanography GA FH289 UT WOS:A1991FH28900008 ER PT J AU CHAN, WS REHFIELD, LW OBRIEN, TK AF CHAN, WS REHFIELD, LW OBRIEN, TK TI ANALYSIS, PREDICTION, AND PREVENTION OF EDGE DELAMINATION IN ROTOR SYSTEM STRUCTURES SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article ID COMPREHENSIVE THEORY; COMPOSITE; STRESS; LAMINATE; PLATES AB Analytical methods such as simple sublaminate analysis, as well as quasi three-dimensional finite element analysis, provide insight into delamination characteristics and reliable trend data with which to make rapid evaluations of competitive concepts in the design environment. It is concluded that free edge delamination can be predicted by analysis and prevented by design. However, in order to ensure durable composite structures, more work is needed to characterize delamination that occurs from other sources, such as matrix cracking and ply drops. C1 UNIV CALIF DAVIS,DEPT MECH AERONAUT & MAT ENGN,DAVIS,CA 95616. NASA,LANGLEY RES CTR,USA RES & TECHNOL ACTIV,AEROSTRUCT DIRECTORATE,HAMPTON,VA 23665. RP CHAN, WS (reprint author), UNIV TEXAS,DEPT MECH ENGN,CTR COMPOSITE MAT,ARLINGTON,TX 76019, USA. NR 43 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 APR PY 1991 VL 36 IS 2 BP 44 EP 51 PG 8 WC Engineering, Aerospace SC Engineering GA FK440 UT WOS:A1991FK44000004 ER PT J AU CHENG, VHL SRIDHAR, B AF CHENG, VHL SRIDHAR, B TI CONSIDERATIONS FOR AUTOMATED NAP-OF-THE-EARTH ROTORCRAFT FLIGHT SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB In this paper, we consider nap-of-the-earth (NOE) rotorcraft flight as one of the applications in which obstacle avoidance plays a key role, and investigate the prospects of automating the guidance functions of NOE flight. Based on a proposed structure for the guidance functions, we identify obstacle detection and obstacle avoidance as the two critical components requiring substantial advancement before an automatic guidance system can be realized. We discuss the major sources of difficulties in developing these two components, including sensor requirements for which we provide a systematic analysis. RP CHENG, VHL (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 13 TC 7 Z9 8 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 APR PY 1991 VL 36 IS 2 BP 61 EP 69 PG 9 WC Engineering, Aerospace SC Engineering GA FK440 UT WOS:A1991FK44000006 ER PT J AU HEYMSFIELD, AJ MILOSHEVICH, LM SLINGO, A SASSEN, K STARR, DOC AF HEYMSFIELD, AJ MILOSHEVICH, LM SLINGO, A SASSEN, K STARR, DOC TI AN OBSERVATIONAL AND THEORETICAL-STUDY OF HIGHLY SUPERCOOLED ALTOCUMULUS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID CLOUDS; STRATOCUMULUS; NUCLEATION; RADIATION AB Two altocumulus clouds, which formed at a temperature of -30-degrees-C, were sampled using the NCAR King Air aircraft and coincident lidar during the 1986 FIRE cirrus experiment in Wisconsin. The clouds were structurally and thermodynamically similar to stratocumulus, with extensive cloudtop entrainment, a capping temperature inversion, and a dry layer above. The microphysical and radiative properties of both clouds were characterized and modeled numerically. Calculations of droplet concentration and mean diameter profiles compare favorably with the measurements when entrainment effects are incorporated in the model. Radiative transfer calculations suggest radiation played an important role in driving convection in the more dynamically unstable of the two clouds. A simple model shows that radiative cooling causes sufficient negative buoyancy in cloudtop parcels to produce convective instability and to reproduce the observed downdraft velocities. Entrainment of warmer, drier air near cloudtop is shown to partially counteract the radiatively induced negative buoyancy in the downdrafts. C1 UNIV UTAH,SALT LAKE CITY,UT 84112. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP HEYMSFIELD, AJ (reprint author), NATL CTR ATMOSPHER RES,DIV MESO & MICROSCALE METEOROL,BOX 3000,BOULDER,CO 80307, USA. RI Heymsfield, Andrew/E-7340-2011 NR 30 TC 58 Z9 59 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 APR 1 PY 1991 VL 48 IS 7 BP 923 EP 945 DI 10.1175/1520-0469(1991)048<0923:AOATSO>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FH993 UT WOS:A1991FH99300003 ER PT J AU MANNEY, GL FARRARA, JD MECHOSO, CR AF MANNEY, GL FARRARA, JD MECHOSO, CR TI THE BEHAVIOR OF WAVE-2 IN THE SOUTHERN-HEMISPHERE STRATOSPHERE DURING LATE WINTER AND EARLY SPRING SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID MEAN-FLOW INTERACTION; PLANETARY-WAVES; BAROTROPIC INSTABILITY; ZONAL FLOWS; PROPAGATION; TROPOSPHERE; NORTHERN; STATES; JET AB A detailed analysis is presented of the behavior of the zonal wavenumber 2 component of the flow (wave 2) for July through October in the Southern Hemisphere stratosphere. Wave 2 in the stratosphere is characterized by a broad meridional structure peaking between 55-degrees and 65-degrees-S, and regular eastward propagation, with periods ranging from 5 to 40 days. Maximum geopotential height amplitudes for a year range from approximately 600 to 1000 m. Examination of vertical structure suggests that during episodes of largest growth, wave 2 propagates upward from the upper troposphere. Regular eastward propagation is, however, evident only within the stratosphere. There are also episodes of wave 2 growth that do not appear connected with the troposphere; in general, the wave 2 amplitude is not as large in these cases. There are several years when wave 1 and wave 2 amplitudes are strongly anticorrelated in time during September and October. There are also years with strong positive correlation during August and September. While wave 1 is usually quasi-stationary, a number of instances where wave 1 moves eastward with wave 2 are observed, lasting from 4 to 10 days. Calculations show that the zonal mean state of the Southern Hemisphere stratosphere frequently satisfies conditions for instability. It is suggested that instability of zonally symmetric and asymmetric states, and nonlinear interactions between wave 1 and wave 2 both play a role in determining the behavior of wave 2 in the Southern Hemisphere winter and spring stratosphere. C1 UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024. RP MANNEY, GL (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 39 TC 43 Z9 43 U1 1 U2 2 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 APR 1 PY 1991 VL 48 IS 7 BP 976 EP 998 DI 10.1175/1520-0469(1991)048<0976:TBOWIT>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FH993 UT WOS:A1991FH99300007 ER PT J AU Nelson, HF Park, C Whiting, EE AF Nelson, H. F. Park, Chul Whiting, Ellis E. TI Titan Atmospheric Composition by Hypervelocity Shock-Layer Analysis SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB Planning is currently underway to send a probe into the atmosphere of Titan (a moon of Saturn) as part of the Cassini Mission. This paper presents an investigation of the feasibility of determining the mole fractions of the major species in Titan's atmosphere (N-2, CH4, and argon, if present) using a radiometer to measure the CN(violet) radiation emitted in the probe's shock layer during the high-velocity portion of the entry. Radiative heating rates spectra are calculated at the probe stagnation point for altitudes near peak heating where the shock-layer gases are in chemical and thermal nonequilibrium. The analysis indicates that the sensitivity of the CN(violet) radiation to the atmospheric composition enables the mole fractions of N-2, CH4, and argon lobe determined to about +/- 0.015, +/- 0.003, and +/- 0.01, respectively. These values are much less than the current uncertainties. The maximum nonequilibrium radiative heating rate is predicted to be about half of the maximum convective heating rate. (Prior equilibrium calculations had shown that the radiative heating rate was negligible.) Thus, the beryllium heat shield currently planned may be underdesigned, because it has been developed for convective heating only. C1 [Nelson, H. F.] Univ Missouri, Dept Mech & Aerosp Engn, Thermal Radiat Transfer Grp, Rolla, MO 65401 USA. [Park, Chul] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA. [Whiting, Ellis E.] Eloret Inst, Sunnyvale, CA 94087 USA. RP Nelson, HF (reprint author), Univ Missouri, Dept Mech & Aerosp Engn, Thermal Radiat Transfer Grp, Rolla, MO 65401 USA. NR 29 TC 7 Z9 7 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD APR-JUN PY 1991 VL 5 IS 2 BP 157 EP 165 DI 10.2514/3.243 PG 9 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZV UT WOS:000208449200005 ER PT J AU Singh, DJ Kumar, A Tiwari, SN AF Singh, D. J. Kumar, A. Tiwari, S. N. TI Effect of Nose Bluntness on Flowfield Over Slender Bodies in Hypersonic Flows SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Article AB A parametric study has been conducted to determine the effects of nose bluntness on the entire flowfield over slender bodies under different hypersonic freestream conditions. The slender bodies considered are blunted cones and ogives. The analysis is carried out for air under perfect- and equilibrium-gas assumptions. The analyses range from a few simplified approaches to the solution of the complete Navier-Stokes equations. The numerical procedures are based on the solution of the Navier-Stokes and parabolized Navier-Stokes equations. Specific results obtained for spherically blunted cones and ogives demonstrate that there are significant differences in flowfield and surface quantities between sharp and blunted bodies. Depending upon the flow conditions and geometry, the differences are found to persist as far as 260 nose radii downstream. C1 [Singh, D. J.; Tiwari, S. N.] Old Dominion Univ, Dept Mech Engn & Mech, Norfolk, VA 23529 USA. [Kumar, A.] NASA, Langley Res Ctr, Theoret Flow Phys Branch, Div Fluid Mech, Hampton, VA 23665 USA. RP Singh, DJ (reprint author), Analyt Syst & Mat Inc, Hampton, VA USA. NR 38 TC 0 Z9 1 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD APR-JUN PY 1991 VL 5 IS 2 BP 166 EP 171 DI 10.2514/3.244 PG 6 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA V24ZV UT WOS:000208449200006 ER PT J AU SUN, DC BREWE, DE AF SUN, DC BREWE, DE TI A HIGH-SPEED PHOTOGRAPHY STUDY OF CAVITATION IN A DYNAMICALLY LOADED JOURNAL BEARING SO JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME LA English DT Article ID SQUEEZE FILM DAMPER AB The earlier study made by Jacobson and Hamrock on the cavitation of liquid lubricant films in a dynamically loaded journal bearing was repeated with a quartz sleeve, which was more rigid than the Polymethylmethacrylate (PMMA) sleeve used previously. Various improvements of the test rig were made concomitantly so that the experimental errors could be better controlled and assessed. This paper describes the updated high-speed photography experiment and its results. C1 USAF,AVSCOM,LEWIS RES CTR,ARMY AVIAT RES & TECHNOL ACTIV,CLEVELAND,OH 44135. RP SUN, DC (reprint author), SUNY BINGHAMTON,THOMAS J WATSON SCH ENGN APPL SCI & TECHNOL,DEPT MECH & IND ENGN,BINGHAMTON,NY 13902, USA. NR 11 TC 4 Z9 5 U1 0 U2 4 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 APR PY 1991 VL 113 IS 2 BP 287 EP 294 DI 10.1115/1.2920618 PG 8 WC Engineering, Mechanical SC Engineering GA FJ111 UT WOS:A1991FJ11100009 ER PT J AU GUNDYBURLET, KL RAI, MM STAUTER, RC DRING, RP AF GUNDYBURLET, KL RAI, MM STAUTER, RC DRING, RP TI TEMPORALLY AND SPATIALLY RESOLVED FLOW IN A 2-STAGE AXIAL COMPRESSOR .2. COMPUTATIONAL ASSESSMENT SO JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME LA English DT Article ID AIRFOIL AERODYNAMICS AB Fluid dynamics of turbomachines are complicated because of aerodynamic interactions between rotors and stators. It is necessary to understand the aerodynamics associated with these interactions in order to design turbomachines that are both light and compact as well as reliable and efficient. The current study uses an unsteady, thin-layer Navier-Stokes zonal approach to investigate the unsteady aerodynamics of a multistage compressor. Relative motion between rotors and stators is made possible by the use of systems of patched and overlaid grids. Results have been computed for a 2 1/2-stage compressor configuration. The numerical data compare well with experimental data for surface pressures and wakes. In addition, the effect of grid refinement on the solution is studied. C1 UNITED TECHNOL RES CTR,E HARTFORD,CT 06108. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 15 TC 9 Z9 9 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0889-504X J9 J TURBOMACH JI J. Turbomach.-Trans. ASME PD APR PY 1991 VL 113 IS 2 BP 227 EP 232 DI 10.1115/1.2929090 PG 6 WC Engineering, Mechanical SC Engineering GA HP739 UT WOS:A1991HP73900010 ER PT J AU JUANG, JN WRIGHT, JR AF JUANG, JN WRIGHT, JR TI A MULTIPOINT FORCE APPROPRIATION METHOD BASED UPON A SINGULAR VALUE DECOMPOSITION APPROACH SO JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME LA English DT Article AB Force appropriation methods aim to provide an estimate for the force pattern required to excite a "pure" normal mode in a vibration test where multiple exciters are available. In this paper, a new method based upon a Singular Value Decomposition approach is presented. The appropriated force vector which minimizes the in-phase response components while maximizing the required quadrature components is found, subject to a fixed force norm. The method can accommodate more transducers than exciters and also more exciters than effective degrees of freedom. The method is demonstrated upon a six degree of freedom theoretical model and it is shown that an estimate for the effective degrees of freedom can be obtained. RP JUANG, JN (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 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 1048-9002 J9 J VIB ACOUST JI J. Vib. Acoust.-Trans. ASME PD APR PY 1991 VL 113 IS 2 BP 176 EP 181 DI 10.1115/1.2930166 PG 6 WC Acoustics; Engineering, Mechanical; Mechanics SC Acoustics; Engineering; Mechanics GA HP728 UT WOS:A1991HP72800005 ER PT J AU BURSIK, MI WOODS, AW AF BURSIK, MI WOODS, AW TI BUOYANT, SUPERBUOYANT AND COLLAPSING ERUPTION COLUMNS SO JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH LA English DT Letter ID EXPLOSIVE VOLCANIC-ERUPTIONS; DYNAMICS C1 INST THEORET GEOPHYS,CAMBRIDGE CB3 9EW,ENGLAND. INST GEOPHYS & PLANETARY PHYS,SCRIPPS INST OCEANOG,LA JOLLA,CA 92093. RP BURSIK, MI (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 14 TC 40 Z9 41 U1 0 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0377-0273 J9 J VOLCANOL GEOTH RES JI J. Volcanol. Geotherm. Res. PD APR PY 1991 VL 45 IS 3-4 BP 347 EP 350 DI 10.1016/0377-0273(91)90069-C PG 4 WC Geosciences, Multidisciplinary SC Geology GA FM464 UT WOS:A1991FM46400014 ER PT J AU STRONG, LL GILMER, DS BRASS, JA AF STRONG, LL GILMER, DS BRASS, JA TI INVENTORY OF WINTERING GEESE WITH A MULTISPECTRAL SCANNER SO JOURNAL OF WILDLIFE MANAGEMENT LA English DT Article ID SPECTRAL RESPONSE; REFLECTANCE; WHEAT AB We used a multispectral scanner with an instantaneous-field-of-view (IFOV) that was larger than a goose to inventory winter concentrations of lesser snow geese (Chen caerulescens) on a water background. A simple linear mixture model of the image-forming process was inverted to estimate the proportion of the IFOV covered by geese. The mixture model prediction of the number of geese was 2% less than a manual count of geese on aerial photographs acquired simultaneously. We suggest that it is possible to inventory white geese and dark geese in mixed concentrations on water from visible and shortwave infrared reflectance measurements. Shortwave infrared (1,420-2,440 nm) reflectance measurements may be used to discriminate among dark species of geese. C1 TGS TECHNOL INC,NASA AMES RES CTR,MOFFETT FIELD,CA 94035. US FISH & WILDLIFE SERV,NO PRAIRIE WILDLIFE RES CTR,DIXON,CA 95620. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 28 TC 9 Z9 10 U1 0 U2 1 PU WILDLIFE SOC PI BETHESDA PA 5410 GROSVENOR LANE, BETHESDA, MD 20814-2197 SN 0022-541X J9 J WILDLIFE MANAGE JI J. Wildl. Manage. PD APR PY 1991 VL 55 IS 2 BP 250 EP 259 DI 10.2307/3809147 PG 10 WC Ecology; Zoology SC Environmental Sciences & Ecology; Zoology GA FL596 UT WOS:A1991FL59600007 ER PT J AU DELLACORTE, C SLINEY, HE AF DELLACORTE, C SLINEY, HE TI TRIBOLOGICAL PROPERTIES OF PM212 - A HIGH-TEMPERATURE, SELF-LUBRICATING, POWDER-METALLURGY COMPOSITE SO LUBRICATION ENGINEERING LA English DT Article; Proceedings Paper CT 45TH ANNUAL MEETING OF THE SOC OF TRIBOLOGISTS AND LUBRICATION ENGINEERS CY MAY 07-10, 1990 CL DENVER, CO SP SOC TRIBOLOGISTS & LUBRICAT ENGINEERS AB This paper describes a research program to develop and evaluate a new high temperature, self-lubricating powder metallurgy composite, PM212. PM212 has the same composition as the plasma-sprayed coating, PS212, which contains 70 wt % metal-bonded chromium carbide, 15 wt % silver and 15 wt % barium fluoride/calcium fluoride eutectic. The cartbide acts as a wear resistant matrix and the silver and fluorides act as low and high temperature lubricants, respectively. The PM212 material is prepared by sequential cold press, cold isostatic pressing and sintering techniques. In this study, hemispherically tipped wear pins of PM212 were prepared and slid against superalloy disks at temperatures from 25 to 850-degrees-C in air in a pin-on-disk tribometer. Friction coefficients range from 0.29 to 0.38 and the wear of both the composite pins and superalloy disks was moderate to low in the 10(-5) to 10(-6) mm3 N-1 m-1 range. Preliminary tests indicate that the material has a compressive strength of at least 130 MPa over the entire temperature range of 25 to 900-degrees-C. This material has promise for use as seal inserts, bushings, small inside diameter parts and other applications where plasma-sprayed coatings are impractical or too costly. RP DELLACORTE, C (reprint author), NATL AERONAUT & SPACE ADM,LEWIS RES CTR,CLEVELAND,OH, USA. NR 0 TC 46 Z9 49 U1 1 U2 5 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 APR PY 1991 VL 47 IS 4 BP 298 EP 303 PG 6 WC Engineering, Mechanical SC Engineering GA FF940 UT WOS:A1991FF94000008 ER PT J AU SLINEY, HE DELLACORTE, C AF SLINEY, HE DELLACORTE, C TI A NEW TEST MACHINE FOR MEASURING FRICTION AND WEAR IN CONTROLLED ATMOSPHERES TO 1200-DEGREES-C SO LUBRICATION ENGINEERING LA English DT Article AB This paper describes a new high temperature friction and wear test apparatus (tribometer). The tribometer can be used as a pin-on-disk or pin-on-ring configuration and is specially designed to measure the tribological properties of ceramics and high temperature metallic alloys from room temperature to 1200-degrees-C. Sliding mode can be selected to be either unidirectional at velocities up to 22 m/sec or oscillating at frequencies up to 4.6 Hz and amplitudes up to +/- 60-degrees. The test atmosphere is established by a controlled flow rate of a purge gas. All components within the test chamber are compatible with oxidizing, inert or reducing gases. RP SLINEY, HE (reprint author), NATL AERONAUT & SPACE ADM,LEWIS RES CTR,CLEVELAND,OH, USA. NR 0 TC 13 Z9 13 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 APR PY 1991 VL 47 IS 4 BP 314 EP 319 PG 6 WC Engineering, Mechanical SC Engineering GA FF940 UT WOS:A1991FF94000009 ER PT J AU ABDELHAKIEM, W PATTERSON, JD LEHOCZKY, SL AF ABDELHAKIEM, W PATTERSON, JD LEHOCZKY, SL TI A COMPARISON BETWEEN ELECTRON-MOBILITY IN N-TYPE HG1-XCDXTE AND HG1-XZNXTE SO MATERIALS LETTERS LA English DT Article ID TELLURIDE AB We have calculated the electron mobility in n-type Hg(1-x)Zn(x)Te (MZT) and compared it with that of Hg(1-x)Cd(x)Te (MCT) for the same energy gap, donor concentration and acceptor concentration. The calculated MZT electron mobility was found to be very close to MCT electron mobility. For our calculations, we solved the Boltzmann equation using variational principles. The scattering processes that are of significance for our calculations include the scattering of electrons by: ionized impurities, holes, compositional disorder, acoustic phonons and optical phonons. In the process of calculating the electron mobility for MZT we have set up a table for all the needed material parameters. MZT has been considered as a substitute for MCT for possible use in infrared detectors due to its relative stability and hardness. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP ABDELHAKIEM, W (reprint author), FLORIDA INST TECHNOL,DEPT PHYS & SPACE SCI,MELBOURNE,FL 32901, USA. NR 21 TC 7 Z9 7 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-577X J9 MATER LETT JI Mater. Lett. PD APR PY 1991 VL 11 IS 1-2 BP 47 EP 51 DI 10.1016/0167-577X(91)90188-C PG 5 WC Materials Science, Multidisciplinary; Physics, Applied SC Materials Science; Physics GA FN409 UT WOS:A1991FN40900011 ER PT J AU KOCH, SE DORIAN, PB FERRARE, R MELFI, SH SKILLMAN, WC WHITEMAN, D AF KOCH, SE DORIAN, PB FERRARE, R MELFI, SH SKILLMAN, WC WHITEMAN, D TI STRUCTURE OF AN INTERNAL BORE AND DISSIPATING GRAVITY CURRENT AS REVEALED BY RAMAN LIDAR SO MONTHLY WEATHER REVIEW LA English DT Article ID MORNING GLORY; DOPPLER RADAR; SQUALL LINE; COLD-FRONT; WAVES; ATMOSPHERE; INITIATION; MOISTURE; DIMENSIONS; EVOLUTION AB Detailed moisture observations from a ground-based Raman lidar and special radiosonde data of two disturbances associated with a dissipating gust front are presented. A synthesis of the lidar data with conventional meteorological data, in conjunction with theoretical calculations and comparison to laboratory studies, leads to the conclusion that the disturbances seen in both the lidar and accompanying barograph data represent a weak gravity current and an associated undular bore. The disturbances display excellent coherence over hundreds of kilometers upstream of the lidar site. Bore formation occurs at the leading edge of the gust front coincidentally with the rapid weakening of the gravity current. Analysis suggests that the bore was generated by the collapse of the gravity current into a stable, nocturnal inversion layer, and subsequently propagated along this wave guide at nearly twice the speed of the gravity current. The Raman lidar provided detailed measurements of the vertical structure of the bore and its parent generation mechanism. A mean bore depth of 1.9 km is revealed by the lidar, whereas a depth of 2.2 km is predicted from hydraulic theory. Observed and calculated bore speeds were also found to agree reasonably well with one another (approximately +/- 20%). Comparison of these observations with those of internal bores generated by thunderstorms in other studies reveals that this bore was exceedingly strong, being responsible for nearly tripling the height of a surface-based inversion that had existed ahead of the bore and dramatically increasing the depth of the moist layer due to strong vertical mixing. Subsequent appearance of the relatively shallow gravity current underneath this mixed region resulted in the occurrence of an elevated mixed layer, as confirmed with the special radiosonde measurements. A synthesis of the lidar and radiosonde observations indicates that bore-induced parcel displacements attenuated rapidly at the same height as the level of strongest wave trapping predicted from the theory of Crook. This trapping mechanism, which is due to the existence of a low-level jet, results in a long-lived bore, and seems to be a common phenomenon in the environment of thunderstorm-generated bores and solitary waves. Despite the weakening of a capping inversion by this strong and persistent bore, analysis indicates that the 30-min averaged lifting of 0.7 m s-1 was confined to a too shallow layer near the surface to trigger deep convection, and could only produce scattered low clouds as deduced from the lidar measurements. C1 GEN SCI CORP,LAUREL,MD. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. RP KOCH, SE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 912,BLDG 22,ROOM 322,GREENBELT,MD 20771, USA. NR 43 TC 60 Z9 60 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0027-0644 J9 MON WEATHER REV JI Mon. Weather Rev. PD APR PY 1991 VL 119 IS 4 BP 857 EP 887 DI 10.1175/1520-0493(1991)119<0857:SOAIBA>2.0.CO;2 PG 31 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FK704 UT WOS:A1991FK70400001 ER PT J AU TAKAHASHI, Y CHAN, CH DONG, BL DUTHIE, JG GREGORY, JC HAYASHI, T YOKOMI, H CHRISTL, MJ DERRICKSON, JH EBY, PB FOUNTAIN, WF PARNELL, TA ROBERTS, FE NAGAMIYA, S DAKE, S TOMINAGA, T FUKI, M IYONO, A OGATA, T MIYAMURA, O AF TAKAHASHI, Y CHAN, CH DONG, BL DUTHIE, JG GREGORY, JC HAYASHI, T YOKOMI, H CHRISTL, MJ DERRICKSON, JH EBY, PB FOUNTAIN, WF PARNELL, TA ROBERTS, FE NAGAMIYA, S DAKE, S TOMINAGA, T FUKI, M IYONO, A OGATA, T MIYAMURA, O TI STUDY OF CORRELATIONS OF POSITIVE AND NEGATIVE CHARGED-PARTICLES SO NUCLEAR PHYSICS A LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL CONF ON ULTRARELATIVISTIC NUCLEUS-NUCLEUS COLLISIONS : QUARK MATTER 90 CY MAY 07-11, 1990 CL MENTON, FRANCE SP CNRS, CEA, SOC FRANCAISE PHYS, COLL FRANCE, MINIST RECH & TECHNOL FRANCE, CONSEIL REG PROVENCE COTE AZUR, ENERTEC, HERAEUS, LCCROY RES SYST, MERCK CLEVENOT AB Particle correlations of the central collision events of S-32 + Pb at 200 GeV/AMU have been studied by utilizing a Magnetic-Interferometric-Emulsion-Chamber (MAGIC) detector. Particle angles, momentum, and charge-signs are measured for all produced charged tracks for each event. Two-particle correlation functions, C2 = dN ((p1 - p2) = q)/dp1dp2, for (++), (--) and (+-) particles are examined. A source radius around 4 - 6 fm is observed for overall identical particle correlations, while unexpected short-range correlations of unlike-sign pairs are observed in the high rapidity region. An analysis of unlike-sign pairs in terms of resonance decays indicated that a large amount (40% relative to pions) of eta or omega mesons (decaying into 3-pi), or of scalar iso-scalar sigma mesons (decaying into 2-pi) would be required to explain some of the data. Multi-particle charge-sign clusters are recognized; however, their "run-test" and "conjugate-test" show small deviations from statistical fluctuations. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. COLUMBIA UNIV,DEPT PHYS,NEW YORK,NY 10027. UNIV TOKYO,JAPAN UNIV GRP,ICR,TANASHI,TOKYO 188,JAPAN. RP TAKAHASHI, Y (reprint author), UNIV ALABAMA,SCH SCI,HUNTSVILLE,AL 35899, USA. NR 4 TC 8 Z9 8 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0375-9474 J9 NUCL PHYS A JI Nucl. Phys. A PD APR 1 PY 1991 VL 525 BP C591 EP C594 PG 4 WC Physics, Nuclear SC Physics GA FH892 UT WOS:A1991FH89200082 ER PT J AU YOKOMI, H TAKAHASHI, Y CHAN, CH DONG, BL DUTHIE, JG GREGORY, JC HAYASHI, T CHRISTL, MJ DERRICKSON, JH EBY, PB FOUNTAIN, WF PARNELL, TA ROBERTS, FE NAGAMIYA, S DAKE, S TOMINAGA, T MIYAMURA, O FUKI, M LYONO, A OGATA, T AF YOKOMI, H TAKAHASHI, Y CHAN, CH DONG, BL DUTHIE, JG GREGORY, JC HAYASHI, T CHRISTL, MJ DERRICKSON, JH EBY, PB FOUNTAIN, WF PARNELL, TA ROBERTS, FE NAGAMIYA, S DAKE, S TOMINAGA, T MIYAMURA, O FUKI, M LYONO, A OGATA, T TI RAPIDITY SPACINGS AND INTERMITTENCY ANALYSES BY DIFFERENTIATING CHARGE-SIGN IN 200 GEV/AMU S+PB INTERACTION FROM CERN EMU05 EXPERIMENTS SO NUCLEAR PHYSICS A LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL CONF ON ULTRARELATIVISTIC NUCLEUS-NUCLEUS COLLISIONS : QUARK MATTER 90 CY MAY 07-11, 1990 CL MENTON, FRANCE SP CNRS, CEA, SOC FRANCAISE PHYS, COLL FRANCE, MINIST RECH & TECHNOL FRANCE, CONSEIL REG PROVENCE COTE AZUR, ENERTEC, HERAEUS, LCCROY RES SYST, MERCK CLEVENOT ID HIGH-ENERGY COLLISIONS AB Fluctuations in rapidity are examined, by using CERN EMU05 experimental data differentiating charge-sign in S+Pb collision at 200 GeV/amu. Rapidity spacing analyses show limiting fluctuations at higher order spacings, while Poisson fluctuations are universally indicated in the lower spacings. The limiting behavior suggests that a long-range positive correlation, such as Wigner repulsion, is in order in the rapidity space. No clear evidence for the intermittent phenomena has been observed in the resultant normalized factorial moments in all charged, positively and negatively charged particles, respectively. C1 OKAYAMA UNIV SCI,OKAYAMA 700,JAPAN. UNIV TOKYO,INST COSM RAY RES,TANASHI,TOKYO 188,JAPAN. UNIV ALABAMA,SCH SCI,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. COLUMBIA UNIV,NAVIS LAB,NEW YORK,NY 10027. KOBE UNIV,DEPT PHYS,KOBE 657,JAPAN. OSAKA UNIV,DEPT APPL MATH,TOYONAKA,OSAKA 560,JAPAN. MATSUSHO GAKUEN JUNIOR COLL,MATSUMOTO 39012,JAPAN. RP YOKOMI, H (reprint author), TEZUKAYAMA GAKUIN UNIV,DEPT PHYS,NARA 631,JAPAN. NR 19 TC 3 Z9 3 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0375-9474 J9 NUCL PHYS A JI Nucl. Phys. A PD APR 1 PY 1991 VL 525 BP C365 EP C368 PG 4 WC Physics, Nuclear SC Physics GA FH892 UT WOS:A1991FH89200038 ER PT J AU DOWNIE, JD AF DOWNIE, JD TI DESIGN OF OPTIMAL BINARY PHASE AND AMPLITUDE FILTERS FOR MAXIMIZATION OF CORRELATION PEAK SHARPNESS SO OPTICS LETTERS LA English DT Article ID ONLY FILTERS AB Current binary phase filters used for optical correlation are usually assumed to have uniform amplitude transmission. Here a new type of filter is studied, the binary phase and amplitude filter. If binary phase values of 0 and pi are assumed, the amplitude transmittance values of this type of filter may be optimized to maximize the peak sharpness. For a polarization-encoded binary phase filter this can be translated into optimization of the rotation angle of the output polarizer following the filter spatial light modulator. An analytic expression is presented for the optimum polarizer angle and thus for the optimum binary phase and amplitude filter design. RP DOWNIE, JD (reprint author), NASA,AMES RES CTR,M-S 244-4,MOFFETT FIELD,CA 94035, USA. NR 11 TC 9 Z9 9 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD APR 1 PY 1991 VL 16 IS 7 BP 508 EP 510 DI 10.1364/OL.16.000508 PG 3 WC Optics SC Optics GA FD812 UT WOS:A1991FD81200023 PM 19773982 ER PT J AU FERRANTE, J SCHLOSSER, H SMITH, JR AF FERRANTE, J SCHLOSSER, H SMITH, JR TI GLOBAL EXPRESSION FOR REPRESENTING DIATOMIC POTENTIAL-ENERGY CURVES SO PHYSICAL REVIEW A LA English DT Article ID AB-INITIO CALCULATIONS; BINDING-ENERGY; CONFIGURATION-INTERACTION; GROUND-STATE; MOLECULES; CHEMISORPTION; METALS; SOLIDS; LIF AB We propose a three-parameter expression that gives an accurate fit to diatomic potential curves over the entire range of separation for charge transfers between 0 less-than-or-equal-to delta-Z less-than-or-equal-to 1. It is based on a generalization of the universal binding-energy relation [J. R. Smith et al., Phys. Rev. A 39, 514 (1989)] with a modification that describes the crossover from a partially ionic state to the neutral state at large separations. The expression is tested by comparison with first-principles calculations of the potential curves ranging from covalently bonded to ionically bonded. The expression is also used to calculate spectroscopic constants from a curve fit to the first-principles curves. A comparison is made with experimental values of the spectroscopic constants. C1 CLEVELAND STATE UNIV,DEPT PHYS,CLEVELAND,OH 44115. GM CORP,DEPT PHYS,RES LABS,WARREN,MI 48090. RP FERRANTE, J (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 32 TC 20 Z9 20 U1 2 U2 2 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD APR 1 PY 1991 VL 43 IS 7 BP 3487 EP 3494 DI 10.1103/PhysRevA.43.3487 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA FG216 UT WOS:A1991FG21600031 ER PT J AU SRIVASTAVA, MK TEMKIN, A AF SRIVASTAVA, MK TEMKIN, A TI INCLUSION OF THETA-12 DEPENDENCE IN THE COULOMB-DIPOLE THEORY OF THE IONIZATION THRESHOLD SO PHYSICAL REVIEW A LA English DT Article ID ATOM IMPACT-IONIZATION; ELECTRON; IONS; LAW AB The Coulomb-dipole (CD) theory of the electron-atom impact-ionization threshold law is extended to include the full electronic repulsion r12(-1) (for the case of e-H ionization). We find that the threshold law is altered to the form Q(a) (E) infinity E (lnE)-4M (E) in contrast to the previous angular-independent model [R12(-1) --> (r1 + r2)-1], for which the logarithmic factor was (lnE)-2. The modulation factor remains the same: M (E) = [(1 - D/alpha)sin(alpha lnE + phi)]. This form of Q(a) (E) - which in our theory is the true threshold law - applies over an energy range E < E(a) infinity alpha-4, where alpha almost-equal-to square-root 2R and R defines a radius beyond which the assumptions of the CD theory apply. A second energy regime, E(a) < E < E(b), is also identified wherein the "threshold" law reverts to its angle-independent form Q(b)(E) infinity E (lnE)-2 M (E), where E(b) infinity alpha-2. In the final part of the paper the dipole parameter alpha is estimated to be alpha almost-equal-to 28. This yields numerical estimates of E(a) almost-equal-to 3 x 10(-4) and E(b) almost-equal-to 0.25 eV. Q(b) (E) is the relevant form for the lowest energy range of current experiments [Donahue et al., Phys. Rev. Lett. 48, 1538 (1982); 52, 164(E) (1984); and a spin-asymmetry experiment of Guo et al., Phys. Rev. Lett. 65, 1857 (1990)]. Their results are consistent with the CD law including the numerical values of those parameters which we have estimated. In contrast the latter experiment gives a confidence factor seven orders of magnitude smaller, when fit by the Wannier law for this process. C1 UNIV ROORKEE,DEPT PHYS,ROORKEE 247667,UTTAR PRADESH,INDIA. RP SRIVASTAVA, MK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. NR 20 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 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD APR 1 PY 1991 VL 43 IS 7 BP 3570 EP 3577 DI 10.1103/PhysRevA.43.3570 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA FG216 UT WOS:A1991FG21600043 ER PT J AU CHOI, SR RITTER, JE AF CHOI, SR RITTER, JE TI FRACTOGRAPHIC ANALYSIS OF FUSED-SILICA OPTICAL FIBERS WITH SUBTHRESHOLD INDENTATION FLAWS SO PHYSICS AND CHEMISTRY OF GLASSES LA English DT Letter ID GLASS; SIZE AB The mirror-mist constant for fused silica optical fibres with sub-threshold indentation flaws tested in either an inert or water environment is 2.1 MPa square-root m. Fractographic analysis indicates that failure of these flaws is initiated from a fault considerably smaller than the indent. During fatigue failure this initial flaw grows to become a crack several times larger than the indent. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. UNIV MASSACHUSETTS,AMHERST,MA 01003. RP CHOI, SR (reprint author), CLEVELAND STATE UNIV,CLEVELAND,OH 44115, USA. NR 10 TC 4 Z9 4 U1 0 U2 0 PU SOC GLASS TECHNOLOGY PI SHEFFIELD PA THORNTON 20 HALLAM GATE ROAD, SHEFFIELD, S YORKSHIRE, ENGLAND S10 5BT SN 0031-9090 J9 PHYS CHEM GLASSES JI Phys. Chem. Glasses PD APR PY 1991 VL 32 IS 2 BP 79 EP 80 PG 2 WC Chemistry, Physical; Materials Science, Ceramics SC Chemistry; Materials Science GA FF570 UT WOS:A1991FF57000010 ER PT J AU MANKBADI, RR AF MANKBADI, RR TI MULTIFREQUENCY EXCITED JETS SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID FREE-SHEAR-LAYER; COHERENT STRUCTURES; INSTABILITY WAVES; FINITE-AMPLITUDE; BOUNDARY-LAYER; MIXING LAYER; ROUND JET; TURBULENT; TRANSITION; FLOW AB Nonlinear wave-wave interactions in turbulent jets were investigated based on the integrated energy of each scale of motion in a cross section of the jet. The analysis indicates that two frequency components in the axisymmetric mode can interact with other background frequencies in the axisymmetric mode, thereby amplifying an enormous number of other frequencies. Two frequency components in a single helical mode cannot, by themselves, amplify other frequency components. But combinations of frequency components of helical and axisymmetric modes can amplify other frequencies in other helical modes. The present computations produce several features consistent with experimental observations on two-frequency excitation such as (1) dependence of the interactions on the initial phase differences between the waves, (2) enhancement of the momentum thickness under multifrequency forcing, and (3) the increase in background turbulence under forcing. In a multifrequency-excited turbulent jet the mechanisms contributing to the development of the jet are identified. Mixing enhancement was found to result from the turbulence enhancement rather than simply from the amplification of forced wave components. The excitation waves pump energy from the mean flow to the turbulence, thus enhancing the latter. The high-frequency waves enhance the turbulence close to the jet exit, while the low-frequency waves are most effective farther downstream. RP MANKBADI, RR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 44 TC 11 Z9 11 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD APR PY 1991 VL 3 IS 4 BP 595 EP 605 DI 10.1063/1.858121 PG 11 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FE060 UT WOS:A1991FE06000013 ER PT J AU YANG, KS KIM, J AF YANG, KS KIM, J TI NUMERICAL INVESTIGATION OF INSTABILITY AND TRANSITION IN ROTATING PLANE POISEUILLE FLOW SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID CHANNEL FLOW; CURVED CHANNEL; VORTICES AB Instability and transition in plane Poiseuille flow with spanwise system rotation is studied via direct numerical simulations with initial small-amplitude random disturbances. The results confirm and clarify the recent experimental findings of Alfredsson and Persson [J. Fluid Mech. 202, 543 (1989)]. A large computational domain is used to allow natural selection of the dominant spanwise wavelength of the observed streamwise vortices, and also the streamwise wavelength of the dominant secondary modes which subsequently develop in the presence of the streamwise vortices. Temporal evolutions of these vortices for several different cases are studied in detail. It is found that the spanwise wavelength of the streamwise vortices can be significantly different from that obtained from linear stability analysis. In all cases examined, the unstable primary three-dimensional waves, which develop during the linear stage, are still persistent in the nonlinear stage. It is also found that for the cases in which the primary three-dimensional waves decay, the finite-amplitude streamwise vortices can become unstable to two different three-dimensional secondary modes of instability, depending on the range of Reynolds number (Re) and rotation number (Ro). The first mode has a streamwise wavelength an order of magnitude longer than the spanwise wavelength; the other, referred to by Alfredsson and Persson as the "twisting mode" because of its visual appearance, has a streamwise wavelength comparable to the spanwise wavelength, and is shown to consist of counter-rotating streamwise vortices whose centers oscillate mostly in the vertical direction. It is shown that these modes are nondispersive traveling waves. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP YANG, KS (reprint author), STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305, USA. NR 17 TC 22 Z9 22 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD APR PY 1991 VL 3 IS 4 BP 633 EP 641 DI 10.1063/1.858070 PG 9 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FE060 UT WOS:A1991FE06000016 ER PT J AU PATER, RH WHITLEY, K MORGAN, C CHANG, A AF PATER, RH WHITLEY, K MORGAN, C CHANG, A TI CROSS-LINKING-PROPERTY RELATIONSHIPS IN PMR POLYIMIDE COMPOSITES .1. SO POLYMER COMPOSITES LA English DT Article AB This study examines for the first time how matrix crosslinking affects the composite physical and mechanical properties of a graphite fiber reinforced PMR polyimide composite during long-term isothermal aging. Unidirectional composite specimens of Celion 6000/PMR-P1 were isothermally exposed at 288-degrees-C in air for various time periods up to 5000 h. The matrix crosslink densities were estimated from the kinetic theory of rubber elasticity and shifts in the glass transition temperatures (T(g)S)). The T(g), coefficient of thermal expansion, density, weight loss, moisture absorption, and elevated temperature flexural and interlaminar shear properties were also determined. Several linear relationships were found between the matrix crosslink density and composite physical and mechanical properties. The T(g), initial weight loss and density, and elevated temperature interlaminar shear strength increase with an increase in crosslink density. Conversely, the initial moisture absorption and coefficient of thermal expansion decrease with increasing crosslink density. As expected, the elevated temperature flexural strength and modulus show no direct correlations with crosslink density. Further, after achieving the highest matrix crosslink density, several of the composite properties begin to decrease rapidly. These findings suggest that time-temperature dependent nature of attaining the maximum matrix crosslinking is closely linked to the onset of the composite property degradation. Though much more work is needed, a fundamental understanding of the relationships between matrix crosslinking and composite physical and mechanical property can provide a scientific basis for the prediction of the extent of composite service life not only for PMR polyimides but also for other thermosetting matrix resins, such as epoxies and bismaleimides. C1 PRC KENTRON INC,HAMPTON,VA 23666. RP PATER, RH (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 21 TC 10 Z9 10 U1 0 U2 7 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 APR PY 1991 VL 12 IS 2 BP 126 EP 132 DI 10.1002/pc.750120210 PG 7 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA FH089 UT WOS:A1991FH08900009 ER PT J AU PATER, RH AF PATER, RH TI DYNAMIC MECHANICAL-PROPERTIES OF N-PHENYLNADIMIDE MODIFIED PMR POLYIMIDE COMPOSITES SO POLYMER COMPOSITES LA English DT Article ID BEHAVIOR AB Temperature-frequency dependence of alpha, beta, and gamma transitions was determined using a Rheometrics dynamic spectrometer on a series of unidirectional Celion 600/N-phenylnadimide (PN) modified PMR polyimide composites. The objective was to see if any correlations exist between crosslinked network structure and dynamic mechanical properties. Variation in crosslinked network structures was achieved by altering the polyimide formulation through addition of various quantities of PN into the standard PMR-15 composition. As a control, PMR-15 composite system exhibited well-defined alpha, beta, and gamma transitions in the regions of 360, 100, and -120-degrees-C, respectively. Their activation energies were estimated to be 232, 60, and 14 kcal/mole, respectively. Increasing the amount of PN concentration caused (a) lowering of the activation energies of the three relaxations, (b) a decrease of the glass transition temperature, and (c) increasing intensities of the three damping peaks, compared to the control PMR-15 counterpart. These dynamic mechanical responses were in agreement with formation of a more flexible co-polymer from PN and PMR-15 prepolymer. RP PATER, RH (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 11 TC 4 Z9 5 U1 2 U2 3 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 APR PY 1991 VL 12 IS 2 BP 133 EP 136 DI 10.1002/pc.750120211 PG 4 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA FH089 UT WOS:A1991FH08900010 ER PT J AU STRONG, JP AF STRONG, JP TI COMPUTATIONS ON THE MASSIVELY PARALLEL PROCESSOR AT THE GODDARD-SPACE-FLIGHT-CENTER SO PROCEEDINGS OF THE IEEE LA English DT Article AB The Massively Parallel Processor (MPP) has proven to be a tremendous asset at the Goddard Space Flight Center. In the area of image analysis and in any other scientific discipline in which data can be arranged in a two-dimensional format, the MPP has provided processing speeds hundreds of times faster than most conventional machines available at Goddard. Scientists have been making use of the speed afforded by the MPP extensively for the past seven years. This paper describes four significant algorithms implemented on the MPP at Goddard some of which are still under development. Two are in the area of image analysis. Of the other two, one is a mathematical simulation experiment and the other deals with the efficient transfer of data between distantly separated processors in the MPP array. The first algorithm presented is the automatic determination of elevations from stereo pairs. The second algorithm solves mathematical "logistic" equations capable of producing both "ordered" and "chaotic" (or random) solutions. This work can potentially lead to the simulation of artificial life processes. The third algorithm is the automatic segmentation of images into reasonable regions based on some similarity criterion while the fourth is an implementation of a bitonic sort of data which significantly overcomes the nearest neighbor interconnection constraints on the MPP for transferring data between distant processors. RP STRONG, JP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 936,GREENBELT,MD 20771, USA. NR 8 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 0018-9219 J9 P IEEE JI Proc. IEEE PD APR PY 1991 VL 79 IS 4 BP 548 EP 558 DI 10.1109/5.92047 PG 11 WC Engineering, Electrical & Electronic SC Engineering GA FQ964 UT WOS:A1991FQ96400013 ER PT J AU TOWNSEND, LW SHINN, JL WILSON, JW AF TOWNSEND, LW SHINN, JL WILSON, JW TI INTERPLANETARY CREW EXPOSURE ESTIMATES FOR THE AUGUST 1972 AND OCTOBER 1989 SOLAR PARTICLE EVENTS SO RADIATION RESEARCH LA English DT Note RP TOWNSEND, LW (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,MAIL STOP 493,HAMPTON,VA 23665, USA. NR 8 TC 31 Z9 31 U1 0 U2 2 PU RADIATION RESEARCH SOC PI OAK BROOK PA 2021 SPRING RD, STE 600, OAK BROOK, IL 60521 SN 0033-7587 J9 RADIAT RES JI Radiat. Res. PD APR PY 1991 VL 126 IS 1 BP 108 EP 110 DI 10.2307/3578178 PG 3 WC Biology; Biophysics; Radiology, Nuclear Medicine & Medical Imaging SC Life Sciences & Biomedicine - Other Topics; Biophysics; Radiology, Nuclear Medicine & Medical Imaging GA FG149 UT WOS:A1991FG14900014 PM 2020735 ER PT J AU MOUGINISMARK, P ROWLAND, S FRANCIS, P FRIEDMAN, T GARBEIL, H GRADIE, J SELF, S WILSON, L CRISP, J GLAZE, L JONES, K KAHLE, A PIERI, D ZEBKER, H KRUEGER, A WALTER, L WOOD, C ROSE, W ADAMS, J WOLFF, R AF MOUGINISMARK, P ROWLAND, S FRANCIS, P FRIEDMAN, T GARBEIL, H GRADIE, J SELF, S WILSON, L CRISP, J GLAZE, L JONES, K KAHLE, A PIERI, D ZEBKER, H KRUEGER, A WALTER, L WOOD, C ROSE, W ADAMS, J WOLFF, R TI ANALYSIS OF ACTIVE VOLCANOS FROM THE EARTH OBSERVING SYSTEM SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID SIR-B; EOS; IDENTIFICATION; INTERFEROMETRY; SPECTROMETER; RESOLUTION; ERUPTIONS AB A study of volcanic activity and its effects on the atmosphere is one of 28 interdisciplinary investigations for the Earth Observing System (EOS), due to be launched in 1997 and 1999. The volcanology investigation will include long- and short-term monitoring of selected volcanoes, the detection of precursory activity associated with unanticipated eruptions, and the detailed study of on-going eruptions. The data collected will allow us to address two aspects of volcanism: volcanic landforms and the atmospheric effects of eruptions. A variety of instruments on the two NASA EOS platforms, together with supplemental data from the Japanese and European platforms, will enable the study of local- to regional-scale thermal and deformational features of volcanoes, and the chemical and structural features of volcanic eruption plumes and aerosols. This investigation fits well within the overall goal of the EOS Project, which is to study the regional and global interrelationships between components of the Earth System, because it specifically investigates the links between volcanism, atmospheric chemistry and short-term (1 - 3 year) climate change. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV N DAKOTA,INST SPACE SCI,GRAND FORKS,ND 58201. MICHIGAN TECHNOL UNIV,DEPT GEOL ENGN,HOUGHTON,MI 49931. UNIV WASHINGTON,DEPT GEOL SCI,SEATTLE,WA 98195. APPLE COMP INC,CUPERTINO,CA. RP MOUGINISMARK, P (reprint author), UNIV HAWAII,SCH OCEAN & EARTH SCI & TECHNOL,DEPT GEOL & GEOPHYS,2525 CORREA RD,HONOLULU,HI 96822, USA. RI Glaze, Lori/D-1314-2012; Crisp, Joy/H-8287-2016 OI Crisp, Joy/0000-0002-3202-4416 NR 28 TC 26 Z9 26 U1 1 U2 4 PU ELSEVIER SCIENCE INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0034-4257 J9 REMOTE SENS ENVIRON JI Remote Sens. Environ. PD APR PY 1991 VL 36 IS 1 BP 1 EP 12 DI 10.1016/0034-4257(91)90027-4 PG 12 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA FU113 UT WOS:A1991FU11300001 ER PT J AU SHENG, YL CLATTERBUCK, CH AF SHENG, YL CLATTERBUCK, CH TI A NEW ANTIFOAMING AGENT FOR EPOXY MATERIAL PROCESSING SO SAMPE QUARTERLY-SOCIETY FOR THE ADVANCEMENT OF MATERIAL AND PROCESS ENGINEERING LA English DT Article AB It has been found that fluorodiepoxides are effective antifoaming agents for epoxy processing when applied at a level as low as 0.1 to 0.2%, and there is no adverse effect on the properties of the cured products. The novelty of the fluorodiepoxide is that it is reactive and can copolymerize with a conventional epoxy resin at the same time in the same way in forming an inter-crosslinked polymer network. However, when applied at a high level, compatibility problems may prevail. RP SHENG, YL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 0036-0821 J9 SAMPE QUART PD APR PY 1991 VL 22 IS 3 BP 52 EP 57 PG 6 WC Engineering, Multidisciplinary; Materials Science, Multidisciplinary SC Engineering; Materials Science GA FG931 UT WOS:A1991FG93100008 ER PT J AU OHSAKA, K LIN, JC TRINH, EH PEREPEZKO, JH AF OHSAKA, K LIN, JC TRINH, EH PEREPEZKO, JH TI FREE-ENERGY CHANGE OF OFF-EUTECTIC BINARY-ALLOYS ON SOLIDIFICATION SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 UNIV WISCONSIN,MADISON,WI 53706. RP OHSAKA, K (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 8 TC 1 Z9 1 U1 1 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD APR PY 1991 VL 25 IS 4 BP 945 EP 948 DI 10.1016/0956-716X(91)90254-X PG 4 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA FE918 UT WOS:A1991FE91800035 ER PT J AU SQUYRES, SW ANDERSEN, DW NEDELL, SS WHARTON, RA AF SQUYRES, SW ANDERSEN, DW NEDELL, SS WHARTON, RA TI LAKE HOARE, ANTARCTICA - SEDIMENTATION THROUGH A THICK PERENNIAL ICE COVER SO SEDIMENTOLOGY LA English DT Article ID DRY VALLEY LAKES; LACUSTRINE SEDIMENTS; ALGAL MATS; PLEISTOCENE; CLASSIFICATION; STROMATOLITES; DEPOSITS; WATER AB Lake Hoare in the Dry Valleys of Antarctica is covered with a perennial ice cover more than 3 m thick, yet there is a complex record of sedimentation and of growth of microbial mats on the lake bottom. Rough topography on the ice covering the lake surface traps sand that is transported by the wind. In late summer, vertical conduits form by melting and fracturing, making the ice permeable to both liquid water and gases. Cross-sections of the ice cover show that sand is able to penetrate into and apparently through it by descending through these conduits. This is the primary sedimentation mechanism in the lake. Sediment traps retrieved from the lake bottom indicate that rates of deposition can vary by large amounts over lateral scales as small as 1 m. This conclusion is supported by cores taken in a 3 x 3 grid with a spacing of 1.5 m. Despite the close spacing of the cores, the poor stratigraphic correlation that is observed indicates substantial lateral variability in sedimentation rate. Apparently, sand descends into the lake from discrete, highly localized sources in the ice that may in some cases deposit a large amount of sand into the lake in a very short time. In some locations on the lake bottom, distinctive sand mounds have been formed by this process. They are primary sedimentary structures and appear unique to the perennially ice-covered lacustrine environment. In some locations they are tens of centimeters high and gently rounded with stable slopes; in others they reach approximately 1 m in height and have a conical shape with slopes at angle of repose. A simple formation model suggests that these differences can be explained by local variations in water depth and sedimentation rate. Rapid colonization and stabilization of fresh sand surfaces by microbial mats composed of cyanobacteria, eukaryotic algae, and heterotrophic bacteria produces a complex intercalation of organic and sandy layers that are a distinctive form of modern stromatolites. C1 SAN JOSE STATE UNIV,DEPT GEOL,SAN JOSE,CA 95192. NASA,AMES RES CTR,SOLAR SYST EXPLORAT BRANCH,MOFFETT FIELD,CA 94035. UNIV NEVADA,DESERT RES INST,RENO,NV 89506. RP SQUYRES, SW (reprint author), CORNELL UNIV,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853, USA. NR 40 TC 79 Z9 79 U1 0 U2 2 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0037-0746 J9 SEDIMENTOLOGY JI Sedimentology PD APR PY 1991 VL 38 IS 2 BP 363 EP 379 DI 10.1111/j.1365-3091.1991.tb01265.x PG 17 WC Geology SC Geology GA FM237 UT WOS:A1991FM23700009 PM 11538650 ER PT J AU JEFFERIES, SM DUVALL, TL AF JEFFERIES, SM DUVALL, TL TI A SIMPLE METHOD FOR CORRECTING SPATIALLY RESOLVED SOLAR INTENSITY OSCILLATION OBSERVATIONS FOR VARIATIONS IN SCATTERED-LIGHT SO SOLAR PHYSICS LA English DT Article AB A measurement of the intensity distribution in an image of the solar disk will be corrupted by a spatial redistribution of the light that is caused by the Earth's atmosphere and the observing instrument. If the precise form of the spatial point spread function is known and can be modeled, then the observed image can be corrected for its effects. However, accurate modeling of the spatial point spread function, which can be considered as composed of a 'blurring' component and a 'scattering' component (Zwaan, 1965), is difficult and the correction for its effects is computationally expensive. We introduce a simple correction method that is applicable for solar p-mode intensity observations obtained over a period of time in which there is a significant change in the scattering component of the point spread function. The method circumvents the problems incurred with an accurate determination of the spatial point spread function and its subsequent deconvolution from the observations. The method only corrects the spherical harmonic coefficients that represent the spatial frequencies present in the image and does not correct the image itself. The method is computationally inexpensive and has the potential of being useful in correcting for changes in the blurring component of the point spread function and also for correcting velocity images. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP JEFFERIES, SM (reprint author), UNIV DELAWARE,BARTOL RES INST,NEWARK,DE 19711, USA. RI Duvall, Thomas/C-9998-2012 NR 10 TC 3 Z9 3 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 APR PY 1991 VL 132 IS 2 BP 215 EP 222 DI 10.1007/BF00152283 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FH729 UT WOS:A1991FH72900002 ER PT J AU VASQUEZ, RP GUPTA, A KUSSMAUL, A AF VASQUEZ, RP GUPTA, A KUSSMAUL, A TI X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF CHEMICALLY-ETCHED ND-CE-CU-O SURFACES SO SOLID STATE COMMUNICATIONS LA English DT Article ID PHOTOEMISSION; YBA2CU3O7-X AB Acetic acid, Br2, and HCl solutions are investigated for removing insulating species from Nd1.85Ce0.15CuO4-delta (NCCO) thin film surfaces. X-ray photoelectron spectroscopy (XPS) shows that the HCl etch is most effective, yielding O 1s spectra comparable to those obtained from samples cleaned in vacuum and a clear Fermi edge in the valence band region. Reduction and oxidation reversibly induces and eliminates, respectively, Fermi level states for undoped samples, but has no clearly observable effect on the XPS spectra for doped samples. Reactivity to air is much less for NCCO compared to hole superconductors, which is attributed to the lack of reactive alkaline earth elements in NCCO. C1 IBM CORP,THOMAS J WATSON RES CTR,YORKTOWN HTS,NY 10598. MIT,FRANCIS BITTER NATL MAGNET LAB,CAMBRIDGE,MA 02139. RP VASQUEZ, RP (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 21 TC 16 Z9 16 U1 0 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0038-1098 J9 SOLID STATE COMMUN JI Solid State Commun. PD APR PY 1991 VL 78 IS 4 BP 303 EP 306 DI 10.1016/0038-1098(91)90202-7 PG 4 WC Physics, Condensed Matter SC Physics GA FJ238 UT WOS:A1991FJ23800012 ER PT J AU LIM, SG BREWE, DE AF LIM, SG BREWE, DE TI ON THE NUMERICAL-SOLUTION OF THE DYNAMICALLY LOADED HYDRODYNAMIC LUBRICATION OF THE POINT CONTACT SO TRIBOLOGY TRANSACTIONS LA English DT Article ID FREE-BOUNDARY PROBLEMS; BEARINGS AB The transient analysis of hydrodynamic lubrication of a point-contact is presented. A body-fitted coordinate system is introduced to transform the physical domain to a rectangular computational domain, enabling the use of the Newton-Raphson method for determining pressures and locating the cavitation boundary, where the Reynolds boundary condition is specified. In order to obtain the transient solution, an explicit Euler method is used to effect a time march. The transient dynamic load is a sinusoidal function of time with frequency, fractional loading, and mean load as parameters. Results include the variation of the minimum film thickness and phase-lag with time as functions of excitation frequency. The results are compared with the analytic solution to the transient step bearing problem with the same dynamic loading function. The similarities of the results suggest an approximate model of the point contact minimum film thickness solution. C1 NASA,LEWIS RES CTR,AVSCOM,PROPULS DIRECTORATE,CLEVELAND,OH 44135. RP LIM, SG (reprint author), CASE WESTERN RESERVE UNIV,DEPT MECH ENGN,CLEVELAND,OH 44106, USA. NR 17 TC 0 Z9 0 U1 0 U2 2 PU SOC TRIBOLOGISTS & LUBRICATION ENGINEERS PI PARK RIDGE PA 838 BUSSE HIGHWAY, PARK RIDGE, IL 60068 SN 0569-8197 J9 TRIBOL T JI Tribol. Trans. PD APR PY 1991 VL 34 IS 2 BP 195 EP 204 DI 10.1080/10402009108982027 PG 10 WC Engineering, Mechanical SC Engineering GA FG321 UT WOS:A1991FG32100006 ER PT J AU WYDEVEN, T GOLUB, MA AF WYDEVEN, T GOLUB, MA TI WASTE STREAMS IN A CREWED SPACE HABITAT SO WASTE MANAGEMENT & RESEARCH LA English DT Article DE WASTE STREAMS; GENERATION RATES; CHEMICAL COMPOSITIONS; CREWED SPACE HABITAT; WASTE MANAGEMENT; LONG-DURATION SPACE MISSIONS; NASA RP WYDEVEN, T (reprint author), NATL AERONAUT & SPACE ADM,AMES RES CTR,DIV RECEIVED ADV LIFE SUPPORT,MOFFETT FIELD,CA 94035, USA. NR 0 TC 11 Z9 11 U1 0 U2 4 PU ACADEMIC PRESS LTD PI LONDON PA 24-28 OVAL RD, LONDON, ENGLAND NW1 7DX SN 0734-242X J9 WASTE MANAGE RES JI Waste Manage. Res. PD APR PY 1991 VL 9 IS 2 BP 91 EP 101 DI 10.1016/0734-242X(91)90097-Q PG 11 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA FJ594 UT WOS:A1991FJ59400002 PM 11537680 ER PT J AU ZWALLY, HJ AF ZWALLY, HJ TI GLOBAL WARMING - BREAKUP OF ANTARCTIC ICE SO NATURE LA English DT Editorial Material ID SHEET RP ZWALLY, HJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,GREENBELT,MD 20771, USA. NR 9 TC 11 Z9 11 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD MAR 28 PY 1991 VL 350 IS 6316 BP 274 EP 274 DI 10.1038/350274a0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FD838 UT WOS:A1991FD83800028 ER PT J AU LARSSON, A BORENSTAIN, SI JONSSON, B ANDERSSON, I WESTIN, J ANDERSSON, TG AF LARSSON, A BORENSTAIN, SI JONSSON, B ANDERSSON, I WESTIN, J ANDERSSON, TG TI PHOTON-ASSISTED RESONANT TUNNELING THROUGH VARIABLY SPACED SUPERLATTICE ENERGY FILTERS SO APPLIED PHYSICS LETTERS LA English DT Article ID INFRARED INTERSUBBAND ABSORPTION; QUANTUM WELLS AB We report on the observation of photon-assisted resonant tunneling in a multiple quantum well structure composed of doped quantum wells separated by variably spaced superlattice energy filters. Electrons confined in the quantum wells are excited to the second quantized state by intersubband absorption of incident infrared radiation and are subsequently emitted through the filters under appropriate bias conditions. This is manifested by a distinct peak, with an associated negative differential photoconductance, in the photocurrent versus bias voltage characteristic at low temperatures. C1 CHALMERS UNIV TECHNOL,DEPT OPTOELECTR & ELECT MEASUREMENTS,S-41296 GOTHENBURG,SWEDEN. CHALMERS UNIV TECHNOL,DEPT PHYS,S-41296 GOTHENBURG,SWEDEN. RP LARSSON, A (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 9 TC 3 Z9 3 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAR 25 PY 1991 VL 58 IS 12 BP 1297 EP 1298 DI 10.1063/1.104341 PG 2 WC Physics, Applied SC Physics GA FD368 UT WOS:A1991FD36800025 ER PT J AU BROWN, RH JOHNSON, TV GOGUEN, JD SCHUBERT, G ROSS, MN AF BROWN, RH JOHNSON, TV GOGUEN, JD SCHUBERT, G ROSS, MN TI TRITONS GLOBAL HEAT-BUDGET SO SCIENCE LA English DT Article ID NEPTUNE AB Internal heat flow from radioactive decay in Triton's interior along with absorbed thermal energy from Neptune total 5 to 20 percent of the insolation absorbed by Triton, thus comprising a significant fraction of Triton's surface energy balance. These additional energy inputs can raise Triton's surface temperature between approximately 0.5 and 1.5 K above that possible with absorbed sunlight alone, resulting in an increase of about a factor of approximately 1.5 to 2.5 in Triton's basal atmospheric pressure. If Triton's internal heat flow is concentrated in some areas, as is likely, local effects such as enhanced sublimation with subsequent modification of albedo could be quite large. Furthermore, indications of recent global albedo change on Triton suggest that Triton's surface temperature and pressure may not now be in steady state, further suggesting that atmospheric pressure on Triton was as much as ten times higher in the recent past. C1 UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,DEPT EARTH & SPACE SCI,LOS ANGELES,CA 90024. AEROSPACE CORP,SPACE SCI LAB,LOS ANGELES,CA 90009. RP BROWN, RH (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 25 TC 16 Z9 16 U1 0 U2 4 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAR 22 PY 1991 VL 251 IS 5000 BP 1465 EP 1467 DI 10.1126/science.251.5000.1465 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FC853 UT WOS:A1991FC85300041 PM 17779439 ER PT J AU CANFIELD, DE DESMARAIS, DJ AF CANFIELD, DE DESMARAIS, DJ TI AEROBIC SULFATE REDUCTION IN MICROBIAL MATS SO SCIENCE LA English DT Article ID COASTAL MARINE-SEDIMENTS; CYANOBACTERIAL MATS; OXYGEN MICROPROFILE; REDUCING BACTERIA; ORGANIC-MATTER; SULFUR; PHOTOSYNTHESIS; SULFIDE AB Measurements of bacterial sulfate reduction and dissolved oxygen (O2) in hypersaline bacterial mats from Baja California, Mexico, revealed that sulfate reduction occurred consistently within the well-oxygenated photosynthetic zone of the mats. This evidence that dissimilatory sulfate reduction can occur in the presence of O2 challenges the conventional view that sulfate reduction is a strictly anaerobic process. At constant temperature, the rates of sulfate reduction in oxygenated mats during daytime were similar to rates in anoxic mats at night: thus, during a 24-hour cycle, variations in light and O2 have little effect on rates of sulfate reduction in these mats. RP CANFIELD, DE (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MAIL STOP 239-4,MOFFETT FIELD,CA 94035, USA. RI Canfield, Don/C-1735-2012 OI Canfield, Don/0000-0001-7602-8366 NR 36 TC 261 Z9 265 U1 3 U2 30 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAR 22 PY 1991 VL 251 IS 5000 BP 1471 EP 1473 DI 10.1126/science.11538266 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FC853 UT WOS:A1991FC85300043 PM 11538266 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR AF BAUSCHLICHER, CW LANGHOFF, SR TI THEORETICAL-STUDY OF THE BONDING OF SC, Y, AND LA SINGLY CHARGED AND DIPOSITIVE IONS TO C2H2, C2H4, AND C3H6 SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAS-PHASE; PERIODIC TRENDS; SCANDIUM IONS; REACTIVITY; ORBITALS; ENERGIES; 1ST-ROW; ETHANE AB The interaction of the Sc and Y singly charged and dipositive ions with C2H2, C2H4, and C3H6 is studied using electronic structure calculations that include high levels of electron correlation. These results are compared with comparable calculations performed previously for La+ and La2+. For C2H2 and C2H4, all three metal ions insert into the C-C pi-bond, making a three-membered ring. The optimal structures for the MC3H6+ ions all involve rearrangement to make a four-membered ring. The strength of the metal-ligand bond for the singly charged ions follows the order La > Sc almost-equal-to Y. In contrast, the bonds involving the dipositive ions are electrostatic, so that the binding energy increases as the size of the ion decreases, leading to the trend Sc > Y > La. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 25 TC 44 Z9 44 U1 1 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD MAR 21 PY 1991 VL 95 IS 6 BP 2278 EP 2282 DI 10.1021/j100159a033 PG 5 WC Chemistry, Physical SC Chemistry GA FD112 UT WOS:A1991FD11200033 ER PT J AU BARTEL, N RUPEN, MP SHAPIRO, II PRESTON, RA RIUS, A AF BARTEL, N RUPEN, MP SHAPIRO, II PRESTON, RA RIUS, A TI A HIGH-RESOLUTION RADIO IMAGE OF A YOUNG SUPERNOVA SO NATURE LA English DT Article ID VLBI OBSERVATIONS; SN-1986J; EMISSION AB Supernovae in our own Galaxy are so rare that images of their remnants 1 can show only the late aftermath of an explosion that occurred anything from a few hundred to several tens of thousands of years ago. Young supernovae are seen frequently in other galaxies, but because they are more distant, it has not been possible until now to obtain high-resolution images that would reveal details of the explosion and the immediate development of the ejected material. Here we present a very-long-baseline interferometric (VLBI) radio image of the bright supernova 1986J, which occurred in the galaxy NGC891 at a distance of approximately 12 Mpc. No detailed image of any supernova or remnant has been obtained before so soon after the explosion. Our image shows a shell of emission with jet-like protrusions. Their analysis should advance our understanding of the dynamics of the expanding debris, the dissipation of energy into the surrounding circumstellar medium, and the evolution of the supernova into the remnant. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. FAC CIENCIAS MATEMAT MADRID,INST ASTRON & GEODESIA,E-28040 MADRID,SPAIN. RP BARTEL, N (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138, USA. RI Antonio, Rius/A-4873-2012 OI Antonio, Rius/0000-0002-5947-2649 NR 24 TC 35 Z9 35 U1 0 U2 1 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD MAR 21 PY 1991 VL 350 IS 6315 BP 212 EP 214 DI 10.1038/350212a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FC779 UT WOS:A1991FC77900049 ER PT J AU TAWEL, R AF TAWEL, R TI ADAPTIVE NEURONS FOR ARTIFICIAL NEURAL NETWORKS SO APPLIED OPTICS LA English DT Note RP TAWEL, R (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1000 EP 1000 PG 1 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600001 ER PT J AU MORRIS, BG AF MORRIS, BG TI CONTROLLING GAS-FLOW MASS RATIOS SO APPLIED OPTICS LA English DT Note RP MORRIS, BG (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1001 EP 1001 PG 1 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600002 ER PT J AU VINOKUR, M AF VINOKUR, M TI FLUX JACOBIAN MATRICES FOR EQUILIBRIUM REAL GASES SO APPLIED OPTICS LA English DT Note RP VINOKUR, M (reprint author), NASA,AMES RES CTR,STERLING FED SYST INC,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1001 EP 1002 PG 2 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600003 ER PT J AU DOLINSKY, S AF DOLINSKY, S TI OPTIMIZATION OF AN ARRAY OF LASER RETROREFLECTORS SO APPLIED OPTICS LA English DT Note RP DOLINSKY, S (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1002 EP 1003 PG 2 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600006 ER PT J AU LEVEQUE, RJ YEE, HC AF LEVEQUE, RJ YEE, HC TI NUMERICAL-METHODS FOR CHEMICALLY REACTING FLOWS SO APPLIED OPTICS LA English DT Note C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP LEVEQUE, RJ (reprint author), UNIV WASHINGTON,SEATTLE,WA 98195, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1002 EP 1002 PG 1 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600005 ER PT J AU MCDERMID, IS WILLIAMSON, WB AF MCDERMID, IS WILLIAMSON, WB TI BEAM STOP FOR HIGH-POWER LASERS SO APPLIED OPTICS LA English DT Note RP MCDERMID, IS (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 1 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1002 EP 1002 PG 1 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600004 ER PT J AU SCHROEDER, JE AF SCHROEDER, JE TI SINTERED FIBER ELECTRODES SO APPLIED OPTICS LA English DT Note RP SCHROEDER, JE (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1003 EP 1003 PG 1 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600007 ER PT J AU COVINGTON, MA SAWKO, PM AF COVINGTON, MA SAWKO, PM TI OPTICAL-PROPERTIES OF CERAMIC FABRICS SO APPLIED OPTICS LA English DT Note RP COVINGTON, MA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1004 EP 1004 PG 1 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600010 ER PT J AU JONES, JA BLUE, G AF JONES, JA BLUE, G TI CHEAPER HYDRIDE-FORMING CATHODES SO APPLIED OPTICS LA English DT Note RP JONES, JA (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1004 EP 1004 PG 1 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600009 ER PT J AU SCHROEDER, JE AF SCHROEDER, JE TI HEAT AND OXIDATION RESISTANT ELECTRODES SO APPLIED OPTICS LA English DT Note RP SCHROEDER, JE (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1004 EP 1004 PG 1 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600008 ER PT J AU RAJAN, N AF RAJAN, N TI MINIMUM TIME SLEWING OF THE SPACE INFRARED TELESCOPE SO APPLIED OPTICS LA English DT Note RP RAJAN, N (reprint author), NASA,AMES RES CTR,STERLING SOFTWARE,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 20 PY 1991 VL 30 IS 9 BP 1005 EP 1005 PG 1 WC Optics SC Optics GA FD016 UT WOS:A1991FD01600011 ER PT J AU SHORE, SN SONNEBORN, G STARRFIELD, SG HAMUY, M WILLIAMS, RE CASSATELLA, A DRECHSEL, H AF SHORE, SN SONNEBORN, G STARRFIELD, SG HAMUY, M WILLIAMS, RE CASSATELLA, A DRECHSEL, H TI MULTIWAVELENGTH OBSERVATIONS OF NOVA LMC-1990 NUMBER-2 - THE 1ST EXTRAGALACTIC RECURRENT NOVA SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES-MAGELLANIC CLOUDS; STARS-NOVAE; ULTRAVIOLET-SPECTRA ID U-SCORPII; OUTBURST AB We present IUE and optical observations of Nova LMC 1990 Number 2, the first recurrent nova to be observed outside the Milky Way. The earlier optical outburst of the nova was observed in 1968, when it reached a maximum of about V = 10.9. IUE spectra were obtained between 1990 February 16 and March 26, with 8 hr resolution during the first day of observations. The ultraviolet observations reported here caught the nova at UV maximum; no P Cygni profiles developed on the resonance lines, suggesting that very little mass was ejected and the outburst was not spherical. The integrated UV luminosity at UV maximum was 2.9 x 10(38) ergs s-1. Thus the luminosity exceeded the Eddington limit for a one solar mass white dwarf [assuming E(B-V) = 0.15 and a distance of 55 kpc to the LMC]. This is the first time that the luminosity of a recurrent nova has been directly obtained. C1 ASSOCIATED UNIV RES ASTRON INC,CERRO TOLOLO INTER AMER OBSERV,LA SERENA,CHILE. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. ARIZONA STATE UNIV,DEPT PHYS & ASTRON,TEMPE,AZ 85287. UNIV CALIF LOS ALAMOS SCI LAB,DIV THEORET,LOS ALAMOS,NM 87545. CNR,IST ASTROFIS SPAZIALE,FRASCATI,ITALY. UNIV ERLANGEN NURNBERG,DR REMEIS STERNWARTE,INST ASTRON,W-8520 ERLANGEN,GERMANY. EUROPEAN SPACE AGCY,VILSPA,IUE OBSERV,MADRID,SPAIN. RP SHORE, SN (reprint author), NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,GODDARD RESOLUT SPECTROGRAPH TEAM,CODE 681,GREENBELT,MD 20771, USA. RI Drechsel, Horst/D-9696-2013; Hamuy, Mario/G-7541-2016 NR 16 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 1991 VL 370 IS 1 BP 193 EP 197 DI 10.1086/169804 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EZ603 UT WOS:A1991EZ60300016 ER PT J AU MADEJSKI, GM MUSHOTZKY, RF WEAVER, KA ARNAUD, KA URRY, CM AF MADEJSKI, GM MUSHOTZKY, RF WEAVER, KA ARNAUD, KA URRY, CM TI A UBIQUITOUS ABSORPTION FEATURE IN THE X-RAY-SPECTRA OF BL LACERTAE OBJECTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL LACERTAE OBJECTS; LINE IDENTIFICATIONS; X-RAYS-SPECTRA ID PKS 2155-304; OPTICAL OBSERVATIONS; HOT; PKS-2155-304; ULTRAVIOLET; QUASARS; AGN AB We present the broad-band (0.5-20 keV) X-ray spectra of five X-ray bright BL Lac objects observed with the Einstein Observatory Solid State Spectrometer (SSS) and Monitor Proportional Counter (MPC) detectors. The combination of moderate energy resolution and broad spectral coverage allows us to confirm the presence of an absorption feature at an energy of approximately 650 eV in the BL Lac object PKS 2155-304, originally reported by Canizares & Kruper based on higher resolution Einstein Objective Grating Spectrometer (OGS) data. Furthermore, the SSS/MPC data indicate that such a feature, presumably due to O VIII Ly-alpha resonant absorption, is present in all BL Lac objects in our sample. This suggests that such features are ubiquitous in at least X-ray-bright BL Lac objects. C1 UNIV SPACE RES ASSOC,COLUMBIA,MD. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. UNIV MARYLAND,COLLEGE PK,MD 20742. RP MADEJSKI, GM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,CODE 666,GREENBELT,MD 20771, USA. RI Urry, Claudia/G-7381-2011 OI Urry, Claudia/0000-0002-0745-9792 NR 31 TC 49 Z9 49 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 MAR 20 PY 1991 VL 370 IS 1 BP 198 EP 204 DI 10.1086/169805 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EZ603 UT WOS:A1991EZ60300017 ER PT J AU HOBAN, S REUTER, DC MUMMA, MJ STORRS, AD AF HOBAN, S REUTER, DC MUMMA, MJ STORRS, AD TI MOLECULAR-HYDROGEN IN THE VICINITY OF NGC-7538 IRS-1 AND IRS-2 - TEMPERATURE AND ORTHO-TO-PARA RATIO SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR-MOLECULES; NEBULAE-ABUNDANCES; NEBULAE-H-II REGIONS; NEBULAE-INDIVIDUAL (NGC-7538); STARS-FORMATION ID H-II REGIONS; STAR FORMATION; H-2 EMISSION; OH SOURCES; CLOUD; SPECTROSCOPY; NGC-2023; IMAGES; GAS AB We made near-infrared spectroscopic observations of the active star-forming region near NGC 7538 IRS 1 and IRS 2. The relative intensities of the upsilon = 1 --> 0 Q(1), Q(3), and Q(5) lines of molecular hydrogen are used to calculate a rotational excitation temperature. The I(Q)(3):I(Q)(1) line intensity ratio implies a rotational temperature of approximately 763 +/- 27 K. The I(Q)(5):I(Q)(1) line intensity ratio implies a rotational temperature of approximately 971 +/- 37 K. Comparison of the measured intensity of the Q(2) transition relative to the intensity of Q(1) and Q(3) permitted the retrieval of the ratio of ortho-to-para hydrogen. We find that a ortho-to-para ratio of between 1.6 and 2.35 is needed to explain the Q-branch line intensity ratios, depending on the excitation model used. This range in ortho-to-para ratios implies a range of molecular hydrogen formation temperature of approximately 105 K to 140 K. C1 NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,GREENBELT,MD 20771. RI mumma, michael/I-2764-2013 NR 25 TC 10 Z9 10 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 1991 VL 370 IS 1 BP 228 EP 236 DI 10.1086/169808 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EZ603 UT WOS:A1991EZ60300020 ER PT J AU CANUTO, VM MAZZITELLI, I AF CANUTO, VM MAZZITELLI, I TI STELLAR TURBULENT CONVECTION - A NEW MODEL AND APPLICATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE CONVECTION; STARS-INTERIORS; TURBULENCE ID INTERACTION APPROXIMATION TREATMENT; ROTATING SPHERICAL-SHELL; LOW-MASS STARS; COMPRESSIBLE CONVECTION; DEEP ATMOSPHERE; INSTABILITY; EQUATIONS; FLUID AB In the interior of stars, convective turbulence (1) is characterized by eddies of all sizes and (2) is compressible (the sound speed is finite). The mixing-length theory (MLT) approximates the first by assuming that there is only one large eddy, and the second by treating turbulence as incompressible. Here, we correct the first MLT approximation. Using two modern theories of turbulence, we compute the full spectrum of eddies and propose a new formula for the turbulent convective flux F(c) to replace the corresponding MLT expression. At high convective efficiencies, the new F(c) is up to 10 times larger than F(c)(MLT), a result recently confirmed by direct numerical simulation of turbulent convection. We also calculate the turbulent pressure exactly. As for the second MLT approximation, we retain the incompressibility condition but improve over the MLT by employing two expressions for the mixing length: (1) the standard LAMBDA = alpha-H(p) and (2) a new expression free of adjustable parameters, LAMBDA = z, where z is the distance to the top of the convective zone. We apply the new model to study the evolution of a 1 M . star and of a globular cluster star of 0.8 M .. With LAMBDA = alpha-H(p), the fit to the data requires alpha = 0.7, thus eliminating the inconsistency of an alpha > 1 usually required by the MLT formalism. With LAMBDA = z, we fit the effective temperature of the Sun within 0.2% without free parameters. Implications for helioseismology are briefly discussed. We also discuss the evolutionary tracks of a solar red giant, a globular cluster main sequence, and a red giant of 0.8 M .. The new model predicts a subatmospheric density inversion larger than that given by the MLT. Also, the observational turnoff of globular clusters requires a larger mass and thus a younger age, a result of possible cosmological interest. Future applications of the new model are discussed, together with suggestions of how to incorporate the new model in stellar evolutionary codes. Although much work remains to be done to assess the compatibility of the new model with a wider set of observational data, as well as to treat compressibility effects, we believe that the three new ingredients, (1) the full spectrum of turbulent eddies, (2) the absence of free parameters in the LAMBDA = z model, and (3) the fit to the Sun's data, have resulted in a model considerably more robust and complete than the MLT. C1 CNR, IST ASTROFIS SPAZIALE, I-00044 FRASCATI, ITALY. RP CANUTO, VM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, INST SPACE STUDIES, 2880 BROADWAY, NEW YORK, NY 10025 USA. NR 65 TC 508 Z9 509 U1 1 U2 4 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 MAR 20 PY 1991 VL 370 IS 1 BP 295 EP 311 DI 10.1086/169815 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EZ603 UT WOS:A1991EZ60300027 ER PT J AU BEICHMAN, CA HELOU, G AF BEICHMAN, CA HELOU, G TI WHAT COBE MIGHT SEE - THE FAR-INFRARED COSMOLOGICAL BACKGROUND SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC BACKGROUND RADIATION; COSMOLOGY; GALAXIES, GENERAL; INFRARED; SOURCES ID LUMINOSITY FUNCTION; GALAXIES; EMISSION; REDSHIFT; QUASARS; GRAINS AB The redshifted emission from infrared luminous galaxies should produce a diffuse background around 300-mu-m detectable by the Cosmic Background Explorer (COBE). The detection of such emission would provide evidence for evolution in the density or luminosity of galaxies in the infrared. C1 INST ADV STUDY,PRINCETON,NJ 08540. RP BEICHMAN, CA (reprint author), CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91109, USA. NR 38 TC 35 Z9 35 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 MAR 20 PY 1991 VL 370 IS 1 BP L1 EP L4 DI 10.1086/185963 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EZ604 UT WOS:A1991EZ60400001 ER PT J AU EHHALT, DH SCHMIDT, U ZANDER, R DEMOULIN, P RINSLAND, CP AF EHHALT, DH SCHMIDT, U ZANDER, R DEMOULIN, P RINSLAND, CP TI SEASONAL CYCLE AND SECULAR TREND OF THE TOTAL AND TROPOSPHERIC COLUMN ABUNDANCE OF ETHANE ABOVE THE JUNGFRAUJOCH SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID C2-C5 HYDROCARBONS; VERTICAL PROFILES; C2H6; ACETYLENE; SPECTRA; STRATOSPHERE; INCREASE; REGION; EUROPE AB Total column abundances of ethane (C2H6) above the Jungfraujoch Station, Switzerland, 3.58-km altitude, have been deduced from infrared solar spectra recorded in 1951 and from 1984 to 1988. The results were derived from the spectroscopic analysis of the v7 band P(Q3), P(Q1), and R(Q0) subbranches of C2H6 near 2976.8, 2983.4, and 2986.7 cm-1, respectively. The 1984-1988 results obtained from more than 300 observations at 0.005 cm-1 resolution show a definite seasonal variation in the total vertical column abundance of that gas, with a maximum of (1.43 +/- 0.03) x 10(16) molecules/cm2 during March and April and a minimum in the fall. The corresponding C2H6 mixing ratio in the free troposphere was derived to 1.53 +/- 0.14 ppb in early April; the ratio of maximum to minimum C2H6 concentration in the troposphere was found to be 1.88 +/- 0.12. From the analysis of the same spectral features observed in March and April 1951, we have deduced a total vertical column abundance of (1.09 +/- 0.10) x 10(16) molecules/cm2. Assuming an exponential increase with time and correcting for a small decrease in the stratospheric amount of C2H6 due to the man-induced increase in stratospheric chlorine, we obtain a secular trend in the tropospheric burden above the Jungfraujoch equal to (0.85 +/- 0.3)% yr-1. It is argued that this trend is valid for the entire northern hemisphere. C1 UNIV LIEGE, INST ASTROPHYS, B-4200 LIEGE, BELGIUM. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. RP EHHALT, DH (reprint author), FORSCHUNGSZENTRUM JULICH, INST ATMOSPHAR CHEM, W-5170 JULICH, GERMANY. NR 24 TC 37 Z9 37 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 4985 EP 4994 DI 10.1029/90JD02229 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400001 ER PT J AU DEMORE, WB AF DEMORE, WB TI TESTS OF STRATOSPHERIC MODELS - THE REACTIONS OF ATOMIC CHLORINE WITH O3 AND CH4 AT LOW-TEMPERATURE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB The reactions of atomic chlorine with O3 and CH4 are very important in stratospheric ozone photochemistry. The relative rates of these reactions strongly influence the ClO/HCl ratio. However, there remains considerable uncertainty in the absolute rate constants for the two reactions at stratospheric temperatures. Since only the relative rate is of primary importance in the stratosphere, experiments on the competitive chlorination of O3/CH4 mixtures have been carried out at 197-217 K, with the objective of directly measuring the rate constant ratio in this temperature range. The results show that the absolute rate constants recommended by the NASA Panel for Data Evaluation (DeMore et al., 1990) are accurate on a relative basis to within 15% at stratospheric temperatures. The following rate constant upper limits are also established for temperatures near 200 K: ClO + CH3O2 --> ClOO + CH3O, k < 4 x 10(-12); ClO + CH3O2 --> OClO + CH3O, k < 1 x 10(-15) cm3 molec-1 s-1. RP DEMORE, WB (reprint author), CALTECH, JET PROP LAB, MAIL CODE 183-601, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 8 TC 35 Z9 35 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 4995 EP 5000 DI 10.1029/90JD02737 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400002 ER PT J AU ROOD, RB DOUGLASS, AR KAYE, JA GELLER, MA CHI, YC ALLEN, DJ LARSON, EM NASH, ER NIELSEN, JE AF ROOD, RB DOUGLASS, AR KAYE, JA GELLER, MA CHI, YC ALLEN, DJ LARSON, EM NASH, ER NIELSEN, JE TI 3-DIMENSIONAL SIMULATIONS OF WINTERTIME OZONE VARIABILITY IN THE LOWER STRATOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID GENERAL-CIRCULATION MODEL; NUMERICAL ADVECTION; PLANETARY-WAVES; TRANSPORT; CONSERVATION; CHEMISTRY; SCHEME AB The evolution of ozone has been calculated for the winters of 1979 and 1989 using winds derived from our stratospheric data assimilation system (STRATAN). The ozone fields calculated using this technique are found to compare well with satellite-measured fields for simulations of 2-3 months. Here we present comparisons of model fields with both satellite and sonde measurements to verify that stratospheric transport processes are properly represented by this modeling technique. Attention is focussed on the northern hemisphere middle and high latitudes at the 10-hPa level and below, where transport processes are most important to the ozone distribution. First-order quantities and derived budgets from both the model and satellite data are presented. By sampling the model with a limb-viewing satellite and then Kalman filtering the "observations" of the model, it is shown that transient subplanetary-scale features that are essential to the ozone budget are missed by the satellite system. C1 APPL RES CORP, LANDOVER, MD USA. SUNY STONY BROOK, INST TERR & PLANETARY ATMOSPHERES, STONY BROOK, NY 11794 USA. RP ROOD, RB (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHER CHEM & DYNAM BRANCH, CODE 916, GREENBELT, MD 20771 USA. RI Allen, Dale/F-7168-2010; Douglass, Anne/D-4655-2012; Rood, Richard/C-5611-2008 OI Allen, Dale/0000-0003-3305-9669; Rood, Richard/0000-0002-2310-4262 NR 33 TC 44 Z9 44 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 5055 EP 5071 DI 10.1029/90JD02537 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400007 ER PT J AU JACKMAN, CH DOUGLASS, AR CHANDRA, S STOLARSKI, RS ROSENFIELD, JE KAYE, JA NASH, ER AF JACKMAN, CH DOUGLASS, AR CHANDRA, S STOLARSKI, RS ROSENFIELD, JE KAYE, JA NASH, ER TI IMPACT OF INTERANNUAL VARIABILITY (1979-1986) OF TRANSPORT AND TEMPERATURE ON OZONE AS COMPUTED USING A 2-DIMENSIONAL PHOTOCHEMICAL MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TWO-DIMENSIONAL MODEL; STRATOSPHERIC PHOTOCHEMISTRY; TRACE GASES; ATMOSPHERE AB Eight years of NMC (National Meteorological Center) temperature and SBUV (solar backscattered ultraviolet) ozone data were used to calculate the monthly mean heating rates and residual circulation for use in a two-dimensional photochemical model in order to examine the interannual variability of modeled ozone. Fairly good correlations were found in the interannual behavior of modeled and measured SBUV ozone in the upper stratosphere at middle to low latitudes, where temperature dependent photochemistry is thought to dominate ozone behavior. The calculated total ozone is found to be more sensitive to the interannual residual circulation changes than to the interannual temperature changes. The magnitude of the modeled ozone variability is similar to the observed variability, but the observed and modeled year to year deviations are mostly uncorrelated. The large component of the observed total ozone variability at low latitudes due to the quasi-biennial oscillation (QBO) is not seen in the modeled total ozone, as only a small QBO signal is present in the heating rates, temperatures, and monthly mean residual circulation. Large interannual changes in tropospheric dynamics are believed to influence the interannual variability in the total ozone, especially at middle and high latitudes. Since these tropospheric changes and most of the QBO forcing are not included in our model formulation, it is not surprising that the interannual variability in total ozone is not well represented in our model computations. C1 APPL RES CORP, LANDOVER, MD 20785 USA. RP NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 916, GREENBELT, MD 20771 USA. RI Douglass, Anne/D-4655-2012; Stolarski, Richard/B-8499-2013; Jackman, Charles/D-4699-2012 OI Stolarski, Richard/0000-0001-8722-4012; NR 34 TC 9 Z9 9 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X EI 2169-8996 J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 5073 EP 5079 DI 10.1029/90JD02661 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400008 ER PT J AU YUE, GK MCCORMICK, MP CHIOU, EW AF YUE, GK MCCORMICK, MP CHIOU, EW TI STRATOSPHERIC AEROSOL OPTICAL DEPTH OBSERVED BY THE STRATOSPHERIC AEROSOL AND GAS EXPERIMENT .2. DECAY OF THE EL-CHICHON AND RUIZ VOLCANIC PERTURBATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SAGE-II; ERUPTION CLOUD; SIZE DISTRIBUTION; SOLAR-RADIATION; DATA VALIDATION; OCTOBER 1982; SAM-II; EXTINCTION; PROFILES; LIDAR AB The decay of the El Chichon perturbation to the optical depth of stratospheric aerosols at 1.02-mu-m, 0.525-mu-m, and 0.453-mu-m is calculated from the Stratospheric Aerosol and Gas Experiment II (SAGE II) data set for the period December 1984 to December 1988. It is found that the perturbed optical depths at middle and higher latitudes of both hemispheres exhibited an exponential decay superimposed by a seasonal oscillation with maximum and minimum occurring in local winter and local summer, respectively. Microphysical processes and variation of the tropopause height alone cannot explain this seasonal change of optical depth. The magnitudes of the exponential component at higher latitudes were, in general, larger than those at lower latitudes. For optical depths in tropical regions, the seasonal oscillations were small and were disturbed by the eruption of Nevado del Ruiz on November 13, 1985. The increase in ratio of optical depth at 0.525-mu-m to that at 1.02-mu-m from about 2.0 at the beginning of 1985 to about 3.5 at the end of 1988 indicates the average size of aerosol particles in the stratosphere is diminishing since the eruption of El Chichon. The 1/e folding time for El Chichon decay derived from the SAGE II data set is in reasonably good agreement with those derived by other methods. C1 ST SYST CORP, HAMPTON, VA 23666 USA. RP YUE, GK (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NR 37 TC 48 Z9 48 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 5209 EP 5219 DI 10.1029/90JD02227 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400020 ER PT J AU KENT, GS MCCORMICK, MP SCHAFFNER, SK AF KENT, GS MCCORMICK, MP SCHAFFNER, SK TI GLOBAL OPTICAL CLIMATOLOGY OF THE FREE TROPOSPHERIC AEROSOL FROM 1.0-MU-M SATELLITE OCCULTATION MEASUREMENTS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID LONG-RANGE TRANSPORT; SAM-II MEASUREMENTS; STRATOSPHERIC AEROSOL; AIR-POLLUTION; CORRELATIVE MEASUREMENTS; CO2-LASER WAVELENGTHS; SAHARAN DUST; SAGE; DISTRIBUTIONS; BACKSCATTER AB Measurements of the aerosol/molecular extinction ratio at 1-mu-m wavelength, obtained from the SAGE I, SAGE II, and SAM II solar occultation satellite experiments between 1978 and 1986, have been used to study the global-scale behavior of the upper tropospheric aerosol. The distribution of extinction ratio values shows a pronounced mode between about 0.5 and 5 in all data subsets, regardless of latitude and season. Within a given latitude band and season the mode value is nearly constant over the altitude range from about 5 km above Earth's surface to 3 km below the tropopause. The mode shows a distinct seasonal variation, with maxima in local spring and summer, and is significantly enhanced following volcanic injection of material into the stratosphere. South of latitude 20-degrees-N, mode values in the absence of volcanic contamination are normally between 0.5 and 1.0. North of 20-degrees-N, values up to about 5 are observed, probably associated with aerosol derived from surface dust or anthropogenic sources. A secondary mode, with extinction ratios of 30 or greater and little or no variation of extinction with wavelength, is apparent just below the tropopause. This mode is believed to be associated with thin cloud along the ray path from the Sun to the satellite. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. RP KENT, GS (reprint author), SCI & TECHNOL CORP, POB 7390, HAMPTON, VA 23666 USA. NR 52 TC 27 Z9 28 U1 3 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 MAR 20 PY 1991 VL 96 IS D3 BP 5249 EP 5267 DI 10.1029/89JD03458 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400024 ER PT J AU KENT, GS YUE, GK AF KENT, GS YUE, GK TI THE MODELING OF CO2 LIDAR BACKSCATTER FROM STRATOSPHERIC AEROSOLS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID EL-CHICHON CLOUD; SULFURIC-ACID; CO2-LASER WAVELENGTHS; SIZE DISTRIBUTION; SULFATE AEROSOLS; SOLAR-RADIATION; OPTICAL DEPTH; DUST CLOUD; ST-HELENS; SAM-II AB Stratospheric aerosol properties, measurement techniques, and long-term data sets are reviewed in the context of the modeling of aerosol characteristics at CO2 laser wavelengths. The techniques for modeling infrared scattering characteristics, both from in situ particle size distribution measurements and from remote optical measurements at other wavelengths, are summarized, and the problems associated with this modeling are discussed. Calculations based on measured size distributions show the backscatter coefficient at wavelength 10.6-mu-m, beta-10.6, to vary by a factor of the order of 100 between background and immediate postvolcanic conditions. The calculated value may also be quite dependent upon the scheme used to interpolate the number concentration between the measured particle radii. The ratio of backscattering at 10.6-mu-m to that at 0.694-mu-m, beta-10.6/beta-0.69, was found to vary by a factor of 5 for the same range of particle size distributions. A description is given of the rather limited amount of modeling at CO2 laser wavelengths and of data intercomparisons that have been published. A comparison of measured backscattering coefficients at 10.6-mu-m with those modeled from shorter wavelengths shows agreement within a factor of 2 or better. Areas of disagreement and uncertainty are identified together with the requirements for improving our knowledge of CO2 laser backscattering from stratospheric aerosols. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. RP KENT, GS (reprint author), SCI & TECHNOL CORP, POB 7390, 101 RES DR, HAMPTON, VA 23666 USA. NR 87 TC 11 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 5279 EP 5292 DI 10.1029/90JD00003 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400026 ER PT J AU ROTHERMEL, J BOWDLE, DA VAUGHAN, JM BROWN, DW WOODFIELD, AA AF ROTHERMEL, J BOWDLE, DA VAUGHAN, JM BROWN, DW WOODFIELD, AA TI CALCULATION OF AEROSOL BACKSCATTER FROM AIRBORNE CONTINUOUS WAVE FOCUSED CO2 DOPPLER LIDAR MEASUREMENTS .1. ALGORITHM DESCRIPTION SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CO2-LASER HETERODYNE SYSTEMS; THEORETICAL SNRS AB Since 1981 the Royal Signals and Radar Establishment and the Royal Aircraft Establishment, United Kingdom, have made vertical and horizontal sounding measurements of aerosol backscatter coefficients at 10.6-mu-m using an airborne continuous wave focused CO2 Doppler lidar, the Laser True Airspeed System (LATAS). The heterodyne signal from the LATAS detector is spectrally analyzed. Then, in conjunction with aircraft flight parameters, the data are processed in a six-stage computer algorithm: set search window, search for peak signal, test peak signal, measure total signal, calculate signal-to-noise ratio (SNR), and calculate backscatter coefficient. C1 UNIV ALABAMA, JOHNSON RES CTR, HUNTSVILLE, AL 35899 USA. ROYAL SIGNALS & RADAR ESTAB, MALVERN WR14 3PS, WORCS, ENGLAND. ROYAL AIRCRAFT ESTAB CTR, DIV FLIGHT SYST, BEDFORD MK41 6AE, BEDS, ENGLAND. RP ROTHERMEL, J (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, HUNTSVILLE, AL 35812 USA. NR 7 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 5293 EP 5298 DI 10.1029/89JD00361 PG 6 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400027 ER PT J AU ROTHERMEL, J BOWDLE, DA VAUGHAN, JM AF ROTHERMEL, J BOWDLE, DA VAUGHAN, JM TI CALCULATION OF AEROSOL BACKSCATTER FROM AIRBORNE CONTINUOUS WAVE FOCUSED CO2 DOPPLER LIDAR MEASUREMENTS .2. ALGORITHM PERFORMANCE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB The performance of an algorithm to calculate aerosol backscatter coefficients, from measurements with an airborne continuous wave focused CO2 Doppler lidar, is described relative to flight hardware settings and operating characteristics, and theoretical considerations. The algorithm (described in paper 1) is used to analyze measurements by the Laser True Airspeed System (LATAS), operated by the Royal Signals and Radar Establishment (RSRE) and Royal Aircraft Establishment (RAE), United Kingdom. Under optimum signal conditions, backscatter signals are located unambiguously and the backscatter coefficients are accurately determined. Under marginal or subthreshold conditions, with a degraded system sensitivity, false alarms (mistaking noise for signal) occur. Parametric studies show that the false alarm rate under these conditions depends on the search window size and the signal-to-noise ratio (SNR) threshold for valid signals. Carefully selected diagnostic parameters are used to estimate the combined sensitivity of the flight hardware system and algorithm. Less than 1% of backscatter measurements for flights over approximately 5 years have been found to be below the measurement sensitivity when the LATAS flight hardware controls were set for optimum sensitivity. C1 UNIV ALABAMA, JOHNSON RES CTR, HUNTSVILLE, AL 35899 USA. ROYAL SIGNALS & RADAR ESTAB, MALVERN WR14 3PS, WORCS, ENGLAND. RP ROTHERMEL, J (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, HUNTSVILLE, AL 35812 USA. NR 3 TC 7 Z9 7 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 5299 EP 5305 DI 10.1029/89JD00362 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400028 ER PT J AU BOWDLE, DA ROTHERMEL, J VAUGHAN, JM BROWN, DW POST, MJ AF BOWDLE, DA ROTHERMEL, J VAUGHAN, JM BROWN, DW POST, MJ TI AEROSOL BACKSCATTER MEASUREMENTS AT 10.6 MICROMETERS WITH AIRBORNE AND GROUND-BASED CO2 DOPPLER LIDARS OVER THE COLORADO HIGH-PLAINS .1. LIDAR INTERCOMPARISON SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CO2-LASER HETERODYNE SYSTEMS; THEORETICAL SNRS; POLARIZATION; CALIBRATION AB An airborne continuous wave (CW) focused CO2 Doppler lidar and a ground-based pulsed CO2 Doppler lidar were used to obtain seven pairs of comparative measurements of tropospheric aerosol backscatter profiles at 10.6-mu-m wavelength, near Denver, Colorado, during a 20-day period in July 1982. In regions of uniform backscatter the two lidars show good agreement, with differences usually less than approximately 50% near 8-km altitude and less than a factor of 2 or 3 elsewhere but with the pulsed lidar often lower than the CW lidar. Near sharp backscatter gradients the two lidars show poorer agreement, with the pulsed lidar usually higher than the CW lidar. Most discrepancies arise from a combination of atmospheric factors and instrument factors, particularly small-scale areal and temporal backscatter heterogeneity above the planetary boundary layer, unusual large-scale vertical backscatter structure in the upper troposphere and lower stratosphere, and differences in the spatial resolution, detection threshold, and noise estimation for the two lidars. C1 NOAA, WAVE PROPAGAT LAB, BOULDER, CO 80303 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, HUNTSVILLE, AL 35812 USA. ROYAL SIGNALS & RADAR ESTAB, MALVERN WR14 3PS, WORCS, ENGLAND. RP BOWDLE, DA (reprint author), UNIV ALABAMA, JOHNSON RES CTR, RE-212, HUNTSVILLE, AL 35899 USA. NR 27 TC 12 Z9 12 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 5327 EP 5335 DI 10.1029/90JD02156 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400031 ER PT J AU BOWDLE, DA ROTHERMEL, J VAUGHAN, JM POST, MJ AF BOWDLE, DA ROTHERMEL, J VAUGHAN, JM POST, MJ TI AEROSOL BACKSCATTER MEASUREMENTS AT 10.6 MICROMETERS WITH AIRBORNE AND GROUND-BASED CO2 DOPPLER LIDARS OVER THE COLORADO HIGH-PLAINS .2. BACKSCATTER STRUCTURE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SIZE DISTRIBUTIONS; 10.6-MU-M; PARTICLES; PROFILES AB Measurements of tropospheric aerosol volume backscatter coefficients at 10.6-mu-m wavelength were obtained with airborne continuous wave and ground-based pulsed CO2 Doppler lidars over the Colorado High Plains during a 20-day period in summer 1982. A persistent "background" layer was found between 6- and 10-km altitude, with a generally uniform backscatter mixing ratio of approximately 10(-10) m2 kg-1 sr-1. The upper boundary of this background layer varied with the tropopause height; the lower boundary varied with the strength and diurnal cycle of convective mixing in the planetary boundary layer (PBL). For quiescent meteorological conditions the transition from the PBL to the background layer was usually very sharp, with backscatter decreases sometimes as large as 3 decades in approximately 70 m. Sharp gradients were also found at the boundaries of shallow (tens of meters) subvisible cirrus clouds. For less stable conditions, associated with vertical aerosol transport by deep cumuliform clouds, backscatter tended to decrease exponentially with altitude. C1 NOAA, WAVE PROPAGAT LAB, BOULDER, CO 80303 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, SPACE SCI LAB, HUNTSVILLE, AL 35812 USA. ROYAL SIGNALS & RADAR ESTAB, MALVERN WR14 3PS, WORCS, ENGLAND. RP BOWDLE, DA (reprint author), UNIV ALABAMA, JOHNSON RES CTR, RE-212, HUNTSVILLE, AL 35899 USA. NR 18 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 5337 EP 5344 DI 10.1029/90JD02157 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400032 ER PT J AU GRAS, JL PLATT, CMR JONES, WD HUFFAKER, RM YOUNG, SA BANKS, SM BOOTH, DJ AF GRAS, JL PLATT, CMR JONES, WD HUFFAKER, RM YOUNG, SA BANKS, SM BOOTH, DJ TI SOUTHERN-HEMISPHERE TROPOSPHERIC AEROSOL BACKSCATTER MEASUREMENTS - IMPLICATIONS FOR A LASER WIND SYSTEM SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OPTICAL-CONSTANTS; WAVELENGTHS AB Values of backscatter coefficient at 0.532-mu-m, 0.694-mu-m, and 10.6-mu-m were determined both by direct measurement and by Mie computation from measured aerosol microphysical properties in the eastern Australian region from 4-degrees-S to 41-degrees-S. Volume backscatter coefficients at 10.6-mu-m were typically in the range 1 x 10(-11) to 3 x 10(-11) m-1 sr-1 for both approaches, although the experimental uncertainty in both cases was quite large. Agreement between the shorter wavelength lidars and the aerosol data was typically within the combined experimental uncertainties, although direct measurements were systematically larger than values derived from the aerosol data; individual regions were observed where the disagreement was larger than the combined error. Backscatter at 10.6-mu-m and at visible wavelengths was found to be sensitive to essentially different regions of the aerosol size spectrum, questioning to some degree the validity of using short-wavelength extinction and backscatter data to infer the global distribution of backscatter at wavelengths around 10.6-mu-m. Considerable day-to-day variability in backscatter was observed at all wavelengths. The implications of the very low backscatter values found, compared to northern hemisphere values, should be considered in the design of the Laser Atmospheric Wind Sounder (LAWS). C1 FOOTSCRAY INST TECHNOL, DEPT APPL PHYS, FOOTSCRAY, VIC 3011, AUSTRALIA. COHERENT TECHNOL INC, BOULDER, CO 80301 USA. CSIRO, DIV ATMOSPHER RES, ASPENDALE, AUSTRALIA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. RI Young, Stuart/A-8641-2011 OI Young, Stuart/0000-0001-6434-9816 NR 20 TC 9 Z9 9 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD MAR 20 PY 1991 VL 96 IS D3 BP 5357 EP 5367 DI 10.1029/88JD03883 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FD794 UT WOS:A1991FD79400034 ER PT J AU MARTINEZ, DA VAILAS, AC GRINDELAND, RE AF MARTINEZ, DA VAILAS, AC GRINDELAND, RE TI THE MATURATION OF CORTICAL BONE IN YOUNG HYPOPHYSECTOMIZED RATS SO FASEB JOURNAL LA English DT Meeting Abstract C1 UNIV WISCONSIN,BIODYNAM LAB,MADISON,WI 53706. NASA,AMES RES CTR,SPACE PHYSIOL BRANCH,MOFFETT FIELD,CA 94035. RI Martinez, Daniel/A-5825-2008 NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 19 PY 1991 VL 5 IS 6 BP A1659 EP A1659 PN 3 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FE557 UT WOS:A1991FE55701179 ER PT J AU SICONOLFI, SF BABB, TG REID, MB MOORE, AD AF SICONOLFI, SF BABB, TG REID, MB MOORE, AD TI INCREASED VENTILATORY RESPONSE TO SUBMAXIMAL EXERCISE AFTER 7 DAYS OF BED REST SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. BAYLOR UNIV,KRUG LIFE SCI,HOUSTON,TX 77030. NR 0 TC 1 Z9 1 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 19 PY 1991 VL 5 IS 6 BP A1477 EP A1477 PN 3 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FE557 UT WOS:A1991FE55700112 ER PT J AU BERSHADY, MA RESSELL, MT TURNER, MS AF BERSHADY, MA RESSELL, MT TURNER, MS TI TELESCOPE SEARCH FOR A 3-EV TO 8-EV AXION SO PHYSICAL REVIEW LETTERS LA English DT Article ID X-RAY OBSERVATIONS; RICH CLUSTERS; GALAXIES AB Axions of mass 3-8 eV should have a cosmological abundance of about 50 cm-3 and reside in rich clusters of galaxies. Their decays to two photons will produce a line at a wavelength lambda-alpha approximately 3100-8300 angstrom (width DELTA-lambda/lambda approximately 10(-2)). We have searched unsuccessfully for such a feature in the intergalactic light of three rich clusters, closing this "window," and leaving open only the window from 10(-6) to 10(-3) eV. This implies that if the axion exists, it likely comprises the dark matter. Our flux limits are of relevance to other relics whose decays produce monoenergetic photons. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637. RP BERSHADY, MA (reprint author), UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637, USA. NR 29 TC 53 Z9 53 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD MAR 18 PY 1991 VL 66 IS 11 BP 1398 EP 1401 DI 10.1103/PhysRevLett.66.1398 PG 4 WC Physics, Multidisciplinary SC Physics GA FB937 UT WOS:A1991FB93700005 ER PT J AU SHULT, PA POLYAK, F DICK, EC WARSHAUER, DM KING, LA MANDEL, AD AF SHULT, PA POLYAK, F DICK, EC WARSHAUER, DM KING, LA MANDEL, AD TI ADENOVIRUS-21 INFECTION IN AN ISOLATED ANTARCTIC STATION - TRANSMISSION OF THE VIRUS AND SUSCEPTIBILITY OF THE POPULATION SO AMERICAN JOURNAL OF EPIDEMIOLOGY LA English DT Article DE ADENOVIRUSES; HUMAN; COLD CLIMATE; COMMON COLD; COMMUNICABLE DISEASES; RESPIRATORY TRACT INFECTIONS; SOCIAL ISOLATION ID RESPIRATORY-INFECTION; RHINOVIRUSES; COLDS AB Natural dissemination of viral respiratory illness to susceptible men may occur with surprising difficulty. This was especially evident during a 1977 outbreak of adenovirus type 21 (Ad-21) at McMurdo Station, a US research base in Antarctica. The unique circumstances at McMurdo allowed 125 men from the US to join and intermingle with 75 men who had wintered for 6 months in complete isolation. For an additional 5-week (September 2 to October 4, 1977) isolation period, respiratory illness etiology and transmission were monitored in the combined population. A total of 89% of the population was susceptible (neutralizing antibody titer, < 1:3) to Ad-21 but only 15.0% were infected. Illness spread very slowly (1.5 cases/100 persons/week) with no epidemic peak and was much less severe than Ad-21 outbreaks in other settings. The incidence of infection (17.3%) and illness (9.6%) was low even in men who had wintered over, with values very similar to those of the newcomers (13.9% and 8.9%, respectively). Thus, despite a harsh environment and frequent prolonged gatherings of susceptible personnel, even a respiratory virus type with known epidemic potential was surprisingly difficult to transmit. C1 USN SUPPORT FORCE ANTARCTICA,PORT HUENEMEL,CA. NATL AERONAUT & SPACE CTR,AMES RES CTR,MOFFETT FIELD,CA. UNIV WISCONSIN,SCH MED,DEPT PREVENT MED,MADISON,WI 53706. NR 33 TC 9 Z9 9 U1 0 U2 3 PU AMER J EPIDEMIOLOGY PI BALTIMORE PA 624 N BROADWAY RM 225, BALTIMORE, MD 21205 SN 0002-9262 J9 AM J EPIDEMIOL JI Am. J. Epidemiol. PD MAR 15 PY 1991 VL 133 IS 6 BP 599 EP 607 PG 9 WC Public, Environmental & Occupational Health SC Public, Environmental & Occupational Health GA FD790 UT WOS:A1991FD79000010 PM 2006647 ER PT J AU BURRIS, J BUTLER, J MCGEE, T HEAPS, W AF BURRIS, J BUTLER, J MCGEE, T HEAPS, W TI QUENCHING AND ROTATIONAL TRANSFER RATES IN THE NU' = 0-MANIFOLD OF OH (A-2-SIGMA+ SO CHEMICAL PHYSICS LA English DT Article ID ENERGY-TRANSFER; VIBRATIONAL-RELAXATION; A2-SIGMA+ OH; V'=1 STATE; FLUORESCENCE; A2SIGMA+; COEFFICIENTS; DEPENDENCE; OD AB We report quenching and rotational transfer rates out of the N' = 1-5 levels of the A 2-SIGMA+ (upsilon' = 0) state of hydroxyl radical (OH) in the presence of oxygen and nitrogen quenching gases. Total depletion rates out of individually excited rotational levels and quenching rates out of the upsilon' = 0 manifold were measured at room temperature. Quenching rates out of initially excited states show a weak dependence upon the rotational quantum number of the initially populated state. Electronic quenching by oxygen was significantly faster than by nitrogen while rotational transfer rates measured with nitrogen were faster than those using oxygen as the collider. C1 ST SYST CORP,LANHAM,MD 20706. RP BURRIS, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 917,GREENBELT,MD 20771, USA. RI McGee, Thomas/G-4951-2013 NR 18 TC 19 Z9 19 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD MAR 15 PY 1991 VL 151 IS 2 BP 233 EP 238 DI 10.1016/0301-0104(91)80104-P PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FC949 UT WOS:A1991FC94900008 ER PT J AU ADAMS, G BELEW, A BUCHANAN, P DUDLEY, G AF ADAMS, G BELEW, A BUCHANAN, P DUDLEY, G TI MUSCLE AREA AFTER LOWER-LIMB SUSPENSION SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,KSC,FL 32899. HOLMES MED CTR,MELBOURNE,FL 32901. BIONET CORP,KSC,FL 32899. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 15 PY 1991 VL 5 IS 5 BP A1037 EP A1037 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FC550 UT WOS:A1991FC55000703 ER PT J AU FORTNEY, SM TROELL, M DUSSACK, L CINTRON, NM AF FORTNEY, SM TROELL, M DUSSACK, L CINTRON, NM TI PLASMA-VOLUME, FLUID BALANCE, AND ENDOCRINE RESPONSES TO PROLONGED LOWER-BODY NEGATIVE-PRESSURE (LBNP) DURING BED REST SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,KRUG LIFE SCI,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 15 PY 1991 VL 5 IS 5 BP A1015 EP A1015 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FC550 UT WOS:A1991FC55000576 ER PT J AU GREENLEAF, JE GEELEN, G SAUMET, JL JUHOS, LT KEIL, LC MEYER, DF WHITTAM, JH AF GREENLEAF, JE GEELEN, G SAUMET, JL JUHOS, LT KEIL, LC MEYER, DF WHITTAM, JH TI VASCULAR UPTAKE OF REHYDRATION FLUIDS IN RESTING HYPOHYDRATED MEN SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV LIFE SCI,HUMAN ENVIRONM PHYSIOL LAB,MOFFETT FIELD,CA 94035. NR 0 TC 2 Z9 2 U1 0 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 15 PY 1991 VL 5 IS 5 BP A1147 EP A1147 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FC550 UT WOS:A1991FC55001328 ER PT J AU GRINDELAND, RE ROY, R EDGERTON, VR GROSSMAN, E RUDOLPH, I PIEROTTI, D GOLDMAN, B AF GRINDELAND, RE ROY, R EDGERTON, VR GROSSMAN, E RUDOLPH, I PIEROTTI, D GOLDMAN, B TI EXERCISE AND GROWTH-HORMONE (GH) HAVE SYNERGISTIC EFFECTS ON SKELETAL-MUSCLE AND TIBIAS OF SUSPENDED RATS SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. UNIV CALIF LOS ANGELES,DEPT KINESIOL,LOS ANGELES,CA 90024. NR 0 TC 6 Z9 6 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 15 PY 1991 VL 5 IS 5 BP A1037 EP A1037 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FC550 UT WOS:A1991FC55000700 ER PT J AU SLIVA, L BARNES, G JAWEED, M AF SLIVA, L BARNES, G JAWEED, M TI INTER-SUBJECT VARIABILITY OF INTEGRATED ELECTROMYOGRAPHY (IEMG) DURING ISOMETRIC MUSCLE CONTRACTIONS SO FASEB JOURNAL LA English DT Meeting Abstract C1 METHODIST HOSP,HOUSTON,TX 77030. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 15 PY 1991 VL 5 IS 5 BP A1117 EP A1117 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FC550 UT WOS:A1991FC55001158 ER PT J AU WADE, CE GREENLEAF, JE KEIL, LC HUNT, MM VERNIKOS, J AF WADE, CE GREENLEAF, JE KEIL, LC HUNT, MM VERNIKOS, J TI ACUTE NEUROENDOCRINE RESPONSES TO ORTHOSTASIS FOLLOWING 30 DAYS OF BEDREST - EFFECTS OF EXERCISE TRAINING SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. LETTERMAN ARMY MED CTR,SAN FRANCISCO,CA 94129. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 15 PY 1991 VL 5 IS 5 BP A1130 EP A1130 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FC550 UT WOS:A1991FC55001233 ER PT J AU WATENPAUGH, DE BALLARD, RE STOUT, MS MURTHY, G WHALEN, RT HARGENS, AR AF WATENPAUGH, DE BALLARD, RE STOUT, MS MURTHY, G WHALEN, RT HARGENS, AR TI DYNAMIC LEG EXERCISE INCREASES TOLERANCE OF LOWER-BODY NEGATIVE-PRESSURE (LBNP) SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 15 PY 1991 VL 5 IS 5 BP A1015 EP A1015 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FC550 UT WOS:A1991FC55000573 ER PT J AU WHITE, MT LANE, HW TEER, P KEITH, RE STRAHAN, S AF WHITE, MT LANE, HW TEER, P KEITH, RE STRAHAN, S TI THE EFFECT OF DIET AND EXERCISE ON INCIDENCE OF 7,12 DIMETHYLBENZ(A)ANTHRACENE-INDUCED MAMMARY-TUMORS IN VIRGIN BALB/C MICE SO FASEB JOURNAL LA English DT Meeting Abstract C1 AUBURN UNIV,DEPT NUTR & FOODS,AUBURN,AL 36830. AUBURN UNIV,COLL VET MED,AUBURN,AL 36830. NASA,DIV MED SCI,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 15 PY 1991 VL 5 IS 5 BP A927 EP A927 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FC550 UT WOS:A1991FC55000064 ER PT J AU HUDSON, CM FERRAINOLO, JJ AF HUDSON, CM FERRAINOLO, JJ TI A COMPENDIUM OF SOURCES OF FRACTURE-TOUGHNESS AND FATIGUE CRACK-GROWTH DATA FOR METALLIC ALLOYS .4. SO INTERNATIONAL JOURNAL OF FRACTURE LA English DT Bibliography RP HUDSON, CM (reprint author), NASA,LANGLEY RES CTR,MS 437,HAMPTON,VA 23665, USA. NR 0 TC 3 Z9 3 U1 0 U2 5 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0376-9429 J9 INT J FRACTURE JI Int. J. Fract. PD MAR 15 PY 1991 VL 48 IS 2 BP R19 EP R43 DI 10.1007/BF00018397 PG 25 WC Materials Science, Multidisciplinary; Mechanics SC Materials Science; Mechanics GA FJ796 UT WOS:A1991FJ79600005 ER PT J AU HEEGER, DJ JEPSON, AD AF HEEGER, DJ JEPSON, AD TI RECOVERING OBSERVER TRANSLATION WITH CENTER-SURROUND MOTION-OPPONENT MECHANISMS SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV TORONTO,DEPT COMP SCI,TORONTO M5S 1A4,ONTARIO,CANADA. NR 1 TC 3 Z9 3 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 MAR 15 PY 1991 VL 32 IS 4 BP 823 EP 823 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76200771 ER PT J AU MCBEATH, MK AF MCBEATH, MK TI EVIDENCE FOR CONSTANCY OF VELOCITY OF APPARENT MOTION SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MOFFETT FIELD,CA 94035. 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 MAR 15 PY 1991 VL 32 IS 4 BP 827 EP 827 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76200787 ER PT J AU MULLIGAN, JB AF MULLIGAN, JB TI A CONTINUOUS VERSION OF THE BARBER-POLE ILLUSION SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 2 Z9 2 U1 0 U2 1 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 MAR 15 PY 1991 VL 32 IS 4 BP 829 EP 829 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76200802 ER PT J AU PAVEL, M SHIFFRAR, M AF PAVEL, M SHIFFRAR, M TI COMPUTATIONAL MODEL OF MOTION INTEGRATION SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NYU,NEW YORK,NY 10003. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. 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 MAR 15 PY 1991 VL 32 IS 4 BP 829 EP 829 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76200801 ER PT J AU MOWAFY, L AF MOWAFY, L TI MOTION-BASED SEGREGATION OF SUPERIMPOSED SURFACES SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,NRC,MOFFETT FIELD,CA 94035. NR 0 TC 2 Z9 2 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 MAR 15 PY 1991 VL 32 IS 4 BP 830 EP 830 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76200804 ER PT J AU PERRONE, JA STONE, LS AF PERRONE, JA STONE, LS TI THE PERCEPTION OF EGOMOTION - GLOBAL VERSUS LOCAL MECHANISMS SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. NR 0 TC 4 Z9 4 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 MAR 15 PY 1991 VL 32 IS 4 BP 957 EP 957 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76201421 ER PT J AU MORIKAWA, K MCBEATH, MK AF MORIKAWA, K MCBEATH, MK TI LATERAL MOTION BIAS ASSOCIATED WITH READING DIRECTION SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 STANFORD UNIV,DEPT PSYCHOL,STANFORD,CA 94305. NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,MOFFETT FIELD,CA 94035. 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 MAR 15 PY 1991 VL 32 IS 4 BP 1042 EP 1042 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76201839 ER PT J AU MEDINA, A GREENE, P AF MEDINA, A GREENE, P TI ANALYTICAL STUDY OF REFRACTIVE DEVELOPMENT OFFERS APPLICATIONS IN MYOPIA PROGRESSION SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. BGKT CONSULTING LTD,HUNTINGTON,NY. 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 MAR 15 PY 1991 VL 32 IS 4 BP 1202 EP 1202 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76202610 ER PT J AU GILLE, J LARIMER, J PIANTANIDA, T LANHAM, J AF GILLE, J LARIMER, J PIANTANIDA, T LANHAM, J TI HUE CANCELLATION ON BINOCULARLY FUSED ADAPTING FIELDS SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SRI INT,MENLO PK,CA 94025. 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 MAR 15 PY 1991 VL 32 IS 4 BP 1213 EP 1213 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76202668 ER PT J AU AHUMADA, AJ AF AHUMADA, AJ TI LEARNABILITY OF RED-GREEN OPPONENCY SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 1 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 MAR 15 PY 1991 VL 32 IS 4 BP 1215 EP 1215 PG 1 WC Ophthalmology SC Ophthalmology GA FC762 UT WOS:A1991FC76202678 ER PT J AU ANICICH, VG SEN, AD HUNTRESS, WT MCEWAN, MJ AF ANICICH, VG SEN, AD HUNTRESS, WT MCEWAN, MJ TI LIFETIME MEASUREMENT OF A COLLISION COMPLEX USING ION-CYCLOTRON DOUBLE-RESONANCE (H2C6N2)-N+ SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID LOW-PRESSURE; RADIATIVE ASSOCIATION AB In the ion-molecule reaction between HC3N+ and HC3N, the lifetime of the collision complex (H2C6N2+)* was long enough that ion cyclotron double resonance techniques could be used to probe the distribution of the lifetimes of the collision complex. The mean lifetime of the collision complex at room temperature was measured as 180-mu-s with a distribution ranging from 60 to 260-mu-s as measured at the half-heights in the distribution. Lifetimes of this magnitude with respect to unimolecular dissociation allow for some stabilization of the collision complex by the slower process of infrared photon emission. C1 UNIV CANTERBURY, DEPT CHEM, CHRISTCHURCH 1, NEW ZEALAND. RP CALTECH, JET PROP LAB, MS 183-601, PASADENA, CA 91109 USA. NR 15 TC 24 Z9 24 U1 0 U2 2 PU AMER INST PHYSICS PI MELVILLE PA 1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USA SN 0021-9606 EI 1089-7690 J9 J CHEM PHYS JI J. Chem. Phys. PD MAR 15 PY 1991 VL 94 IS 6 BP 4189 EP 4191 DI 10.1063/1.460651 PG 3 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FD735 UT WOS:A1991FD73500009 ER PT J AU DRINKWATER, MR AF DRINKWATER, MR TI KU BAND AIRBORNE RADAR ALTIMETER OBSERVATIONS OF MARGINAL SEA ICE DURING THE 1984 MARGINAL ICE-ZONE EXPERIMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID FRAM STRAIT; MICROWAVE; SUMMER AB Pulse-limited, airborne radar data taken in June and July 1984 with a 13.8-GHz altimeter over the Fram Strait marginal ice zone are analyzed with the aid of large-format aerial photography, airborne synthetic aperture radar data, and surface observations. Variations in the radar return pulse waveforms are quantified and correlated with ice properties recorded during the Marginal Ice Zone Experiment. Results indicate that the wide-beam altimeter is a flexible instrument, capable of identifying the ice edge with a high degree of accuracy, calculating the ice concentration, and discriminating a number of different ice classes. This suggests that microwave radar altimeters have a sensitivity to sea ice which has not yet been fully exploited. When fused with SSM/I, AVHRR and ERS-1 synthetic aperture radar imagery, future ERS-1 altimeter data are expected to provide some missing pieces to the sea ice geophysics puzzle. RP DRINKWATER, MR (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Drinkwater, Mark/C-2478-2011 OI Drinkwater, Mark/0000-0002-9250-3806 NR 43 TC 15 Z9 15 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 MAR 15 PY 1991 VL 96 IS C3 BP 4555 EP 4572 DI 10.1029/90JC01954 PG 18 WC Oceanography SC Oceanography GA FC252 UT WOS:A1991FC25200004 ER PT J AU LIU, AK HOLT, B VACHON, PW AF LIU, AK HOLT, B VACHON, PW TI WAVE-PROPAGATION IN THE MARGINAL ICE-ZONE - MODEL PREDICTIONS AND COMPARISONS WITH BUOY AND SYNTHETIC APERTURE RADAR DATA SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID SAR OBSERVATIONS; LABRADOR SEA; OCEAN; FIELD; ATTENUATION; RHEOLOGY; VELOCITY AB In this paper the ocean wave dispersion relation and viscous attenuation by a sea ice cover are studied for waves propagating into the marginal ice zone (MIZ). The derivation of the dispersion relation and the viscous attenuation by an ice sheet are discussed for waves under flexure and pack compression. In the MIZ, the flexure effect is important for short waves. For a fixed wave period the changes in wavelength and group velocity as a function of ice thickness are significant. In turn, the exponential wave attenuation rate shows a rollover at short wave periods, whereby the rapid increase in wave attenuation rate with decreasing wave period slows down or even turns into a decrease. The Labrador Ice Margin Experiment (LIMEX), conducted on the MIZ off the east coast of Newfoundland, Canada, in March 1987, provides us with aircraft synthetic aperture radar (SAR) imagery, wave buoy, and ice property data. On the basis of the wave number spectrum from the SAR data and the concurrent wave frequency spectrum from the ocean buoy data and accelerometer data on the ice during LIMEX '87, the dispersion relation has been estimated and compared with a model. Wave energy attenuation rates are estimated from SAR data and the ice motion package data which were deployed at the ice edge and into the ice pack, and compared with the model. The model-data comparisons are reasonably good for the ice conditions observed during LIMEX '87. Some previously reported data of wave attenuation in the MIZ are revisited for model comparison. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. CANADA CTR REMOTE SENSING,OTTAWA K1A 0Y7,ONTARIO,CANADA. RP LIU, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD 20771, USA. NR 30 TC 44 Z9 45 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD MAR 15 PY 1991 VL 96 IS C3 BP 4605 EP 4621 DI 10.1029/90JC02267 PG 17 WC Oceanography SC Oceanography GA FC252 UT WOS:A1991FC25200007 ER PT J AU PARKINSON, CL AF PARKINSON, CL TI INTERANNUAL VARIABILITY OF THE SPATIAL-DISTRIBUTION OF SEA ICE IN THE NORTH POLAR-REGION SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article AB Passive microwave data from the Nimbus 5 and Nimbus 7 satellites have been used to determine baseline information on the interannual variability in monthly average sea ice distributions in the north polar region over the period 1973-1987. Monthly maps of the spatial range of ice distributions found for the 1973-1987 period show that, for instance, in February the greatest interannual variability occurs in the Sea of Okhotsk and in July particularly high interannual variability occurs in both Hudson Bay and the northern Barents Sea. In contrast, the portions of the ice edge with the least interannual variability in their February ice distributions lie in the southern Greenland Sea (59-degrees-67-degrees-N) and immediately to the south and west of Svalbard. Plots of percent variability by month show that the marginal ice zones of the Sea of Okhotsk and the Bering Sea have their greatest ice distribution variability in winter and early spring, while the central Arctic has its greatest variability in late summer, and Hudson Bay has its greatest variability in July and November, during the ice decay and ice growth seasons, respectively. Since none of the regions showing high variability experienced a consistent (or even near-consistent) trend toward either increasing or decreasing ice coverage, the demonstrated variability cannot easily be attributed to climate change. The maps and analysis presented here provide a 1973-1987 baseline against which future northern hemisphere sea ice distributions can be compared in the continuing attempt to analyze global climate and to determine whether or not significant climate change is occurring. RP PARKINSON, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,CODE 971,GREENBELT,MD 20771, USA. RI Parkinson, Claire/E-1747-2012 OI Parkinson, Claire/0000-0001-6730-4197 NR 16 TC 34 Z9 36 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-OCEANS JI J. Geophys. Res.-Oceans PD MAR 15 PY 1991 VL 96 IS C3 BP 4791 EP 4801 DI 10.1029/91JC00082 PG 11 WC Oceanography SC Oceanography GA FC252 UT WOS:A1991FC25200020 ER PT J AU LIU, AK VACHON, PW PENG, CY AF LIU, AK VACHON, PW PENG, CY TI OBSERVATION OF WAVE REFRACTION AT AN ICE EDGE BY SYNTHETIC APERTURE RADAR SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID OCEAN; BANDS; FIELD; SWELL; SEA AB In this note the refraction of waves at the ice edge is studied by using aircraft synthetic aperture radar (SAR). Penetration of a dominant swell from open ocean into the ice cover was observed by SAR during the Labrador Ice Margin Experiment (LIMEX), conducted on the marginal ice zone (MIZ) off the east coast of Newfoundland, Canada, in March 1987. At an ice edge with a large curvature, the dominant swell component disappeared locally in the SAR imagery. Six subscences of waves in the MIZ from the SAR image have been processed, revealing total reflection, refraction, and energy reduction of the ocean waves by the ice cover. The observed variations of wave spectra from SAR near the ice edge are consistent with the model prediction of wave refraction at the ice edge due to the change of wave dispersion relation in ice developed by Liu and Mollo-Christensen (1988). C1 CANADA CTR REMOTE SENSING,OTTAWA K1A 0Y7,ONTARIO,CANADA. SCI SYST & APPLICAT INC,SEABROOK,MD 20706. RP LIU, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD 20771, USA. NR 19 TC 22 Z9 22 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 MAR 15 PY 1991 VL 96 IS C3 BP 4803 EP 4808 DI 10.1029/90JC02546 PG 6 WC Oceanography SC Oceanography GA FC252 UT WOS:A1991FC25200021 ER PT J AU GLAZMAN, RE AF GLAZMAN, RE TI EFFECTS OF SEA MATURITY ON SATELLITE ALTIMETER MEASUREMENTS - REPLY SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Letter ID DIRECTIONAL SPECTRA; WAVES RP GLAZMAN, RE (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 21 TC 6 Z9 7 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 MAR 15 PY 1991 VL 96 IS C3 BP 4979 EP 4983 DI 10.1029/91JC00060 PG 5 WC Oceanography SC Oceanography GA FC252 UT WOS:A1991FC25200037 ER PT J AU HIROSE, T MI, Y STERN, SA STCLAIR, AK AF HIROSE, T MI, Y STERN, SA STCLAIR, AK TI THE SOLUBILITY OF CARBON-DIOXIDE AND METHANE IN POLYIMIDES AT ELEVATED PRESSURES SO JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS LA English DT Article ID AROMATIC POLYIMIDES; 3,3',4,4'-BIPHENYLTETRACARBOXYLIC DIANHYDRIDE; GAS SORPTION; TRANSPORT; SEPARATION; MORPHOLOGY; POLYMERS; 4,4'-OXYDIANILINE; PERMSELECTIVITY; PERMEABILITY AB The solubility of CO2 and CH4 in five polyimides was measured at 35.0-degrees-C and at pressures up to 10 atm (147 psia). The concentration of the penetrant gases dissolved in the polymers can be represented satisfactorily as a function of penetrant pressure by the "dual-mode sorption" model. The solubility coefficients for CO2 and CH4, S(CO2) and S(CH4), increase in the polyimide order: PMDA-4,4'-m-APPS < 6FDA-4,4'-m-APPS < 6FDA-4,4'-p-APPP < 6FDA-CDA < 6FDA-4,4'-p-APPS The magnitude of the solubility coefficients appears to depend primarily on the intermolecular forces between the penetrant gases and the polymers. The values of these coefficients are greater for the polymides with larger mean interchain spacings, but no one-to-one correspondence appears to exist in this respect. The lower solubility of CO2 in PMDA-4,4'-m-APPS compared with that in the 6FDA polyimides may be due to the lower "excess" free volume of the former polymer. The ratio S(CO2) / S(CH4) varies relatively little for a variety of PMDA and 6FDA polymides. C1 SYRACUSE UNIV,DEPT CHEM ENGN & MAT SCI,SYRACUSE,NY 13244. NASA,LANGLEY RES CTR,DIV MAT,HAMPTON,VA 23665. RI Hirose, Takuji/E-8636-2012 NR 27 TC 13 Z9 13 U1 0 U2 1 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0887-6266 J9 J POLYM SCI POL PHYS JI J. Polym. Sci. Pt. B-Polym. Phys. PD MAR 15 PY 1991 VL 29 IS 3 BP 341 EP 347 DI 10.1002/polb.1991.090290308 PG 7 WC Polymer Science SC Polymer Science GA EY171 UT WOS:A1991EY17100008 ER PT J AU MILLER, TL BUTLER, KA AF MILLER, TL BUTLER, KA TI HYSTERESIS AND THE TRANSITION BETWEEN AXISYMMETRICAL FLOW AND WAVE FLOW IN THE BAROCLINIC ANNULUS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID CONVECTION AB A numerical model is used to determine the transitions between axisymmetric flow and wave flow in the rotating, differentially heated annulus experiments of Fein for both rigid lid and free surface cases. For most of the transitions, the technique of computing a steady axisymmetric flow and then testing its linear stability to wave disturbances results in good agreement with the experiments. Nonlinear calculations with a single azimuthal wave accurately predict the observed hysteresis in the transition for large differential heating rates in the free surface case. Specifically, it is demonstrated that, in the experimentally observed hysteresis region, the Navier-Stokes equations support two stable equilibria for the same values of the external parameters. The hysteresis occurs in conjunction with a jump in wave amplitude as the rotation rate is slowly varied. Analysis of the longitudinal mean states and the linear and nonlinear waves indicates that the jump in amplitude is due to destabilization of the mean flow by the wave because of the reduction of the mean upper-level jet and the lower dissipation in the nonlinear wave. The reduction of the mean jet, which is due to the lowering of the thermal wind by baroclinic energy transfer, results in a smaller barotropic wave energy sink. Some implications for the study of the dynamics of the Earth's atmosphere are discussed. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,NEW TECHNOL INC,HUNTSVILLE,AL 35812. RP MILLER, TL (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,DIV EARTH SCI & APPLICAT,HUNTSVILLE,AL 35812, USA. NR 22 TC 13 Z9 13 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD MAR 15 PY 1991 VL 48 IS 6 BP 811 EP 823 DI 10.1175/1520-0469(1991)048<0811:HATTBA>2.0.CO;2 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FG788 UT WOS:A1991FG78800002 ER PT J AU RICH, DH KSENDZOV, A TERHUNE, RW GRUNTHANER, FJ WILSON, BA SHEN, H DUTTA, M VERNON, SM DIXON, TM AF RICH, DH KSENDZOV, A TERHUNE, RW GRUNTHANER, FJ WILSON, BA SHEN, H DUTTA, M VERNON, SM DIXON, TM TI POLARIZED-CATHODOLUMINESCENCE STUDY OF UNIAXIAL AND BIAXIAL STRESS IN GAAS/SI SO PHYSICAL REVIEW B LA English DT Note ID HETEROEPITAXIAL GAAS; GALLIUM-ARSENIDE; SI; PHOTOLUMINESCENCE; SILICON; RELIEF AB The strain-induced splitting of the heavy-hole (hh) and light-hole (lh) valence bands for 4-mu-m-thick GaAs/Si is examined on a microscopic scale using linear polarized-cathodoluminescence imaging and spectroscopy. The energies and intensities of the hh- and lh-exciton luminescence are quantitatively analyzed to determine spatial variations in the stress tensor. The results indicate that regions near and far from the microcracks are primarily subject to uniaxial and biaxial tensile stresses, respectively. The transition region where biaxial stress gradually converts to uniaxial stress is analyzed, and reveals a mixing of lh and hh characters in the strain-split bands. C1 USA,ELECTR TECHNOL & DEVICES LAB,FT MONMOUTH,NJ 07703. GEOCENTERS INC,NJ OPERAT,LAKE HOPATCONG,NJ 07849. SPIRE CORP,BEDFORD,MA 01730. RP RICH, DH (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 19 TC 34 Z9 34 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 MAR 15 PY 1991 VL 43 IS 8 BP 6836 EP 6839 DI 10.1103/PhysRevB.43.6836 PG 4 WC Physics, Condensed Matter SC Physics GA FC704 UT WOS:A1991FC70400079 ER PT J AU KAMIONKOWSKI, M TURNER, MS AF KAMIONKOWSKI, M TURNER, MS TI DISTINCTIVE POSITRON FEATURE FROM PARTICLE DARK-MATTER ANNIHILATIONS IN THE GALACTIC HALO SO PHYSICAL REVIEW D LA English DT Article ID COSMIC-RAY ANTIPROTONS; PHOTINO-DOMINATED UNIVERSE; INTERACTING MASSIVE PARTICLES; MONOCHROMATIC GAMMA-RAYS; NEUTRAL-FERMION PAIRS; HIGH-ENERGY NEUTRINOS; ASTROPHYSICAL IMPLICATIONS; STANDARD MODEL; 2 PHOTONS; PROBE AB If the dark matter in our galactic halo consists of weakly interacting massive particles (WIMP's) heavier than the W+/- boson which have a significant annihilation branch into W+/- and Z(0) pairs, e.g., a Higgsino-like neutralino, a very distinctive feature in the cosmic-ray positron spectrum arises from W+ and Z(0) decays. Because of inherent astrophysical uncertainties such a signal is by no means guaranteed even if heavy WIMP's do comprise the galactic halo. However, the positron signature is virtually a "smoking gun" for particle dark matter in the halo and thus worthy of note. C1 FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP KAMIONKOWSKI, M (reprint author), UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637, USA. NR 47 TC 123 Z9 126 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 MAR 15 PY 1991 VL 43 IS 6 BP 1774 EP 1780 DI 10.1103/PhysRevD.43.1774 PG 7 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA FC300 UT WOS:A1991FC30000006 ER PT J AU DAVIS, DD WEDLICH, RC MARTIN, NB AF DAVIS, DD WEDLICH, RC MARTIN, NB TI TRANSITION-METAL CATALYSIS OF THE HETEROGENEOUS DECOMPOSITION OF HYDRAZINE - ADIABATIC KINETICS BY ACCELERATING RATE CALORIMETRY SO THERMOCHIMICA ACTA LA English DT Article ID AMMONIA-SYNTHESIS; SURFACE; ENERGY; ADSORPTION; MECHANISM; OXYGEN; FILMS; CO2 AB The thermochemical kinetics of the transition-metal-catalyzed decomposition reaction of hydrazine have been studied using accelerating rate calorimetry. The reaction stoichiometry was determined by both product analysis and thermochemical balance. In the range 350-515 K when both liquid and vapor hydrazine are present, the decomposition proceeds according to: C1 NASA,LOCKHEED ENGN & SCI CO,WHITE SANDS TEST FACIL,LAS CRUCES,NM 88004. RP DAVIS, DD (reprint author), NEW MEXICO STATE UNIV,DEPT CHEM,LAS CRUCES,NM 88003, USA. NR 52 TC 6 Z9 6 U1 1 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-6031 J9 THERMOCHIM ACTA JI Thermochim. Acta PD MAR 15 PY 1991 VL 175 IS 2 BP 175 EP 188 DI 10.1016/0040-6031(91)80064-P PG 14 WC Thermodynamics; Chemistry, Analytical; Chemistry, Physical SC Thermodynamics; Chemistry GA FE279 UT WOS:A1991FE27900006 ER PT J AU DAVIS, DD WEDLICH, RC AF DAVIS, DD WEDLICH, RC TI KINETICS AND MECHANISM OF THE THERMAL-DECOMPOSITION OF MONOMETHYLHYDRAZINE BY ACCELERATING RATE CALORIMETRY SO THERMOCHIMICA ACTA LA English DT Article ID COMPENSATION AB The thermal decomposition reaction of monomethylhydrazine was studied using an accelerating rate calorimeter. Nitrogen, ammonia, methylamine, methane and ethane were the major products. Dimethylamine, 1,2-dimethyldiazene and traces of nine other nitrogenous compounds or hydrocarbons were observed in the product mixture. The Arrhenius parameters for the decomposition reaction are compensated and linearly related by the relationship 1n A = E(a)/R-theta + 1n k0, with a compensation temperature theta of 478 K. The isokinetic temperature is 475 K. Activation energies were found to be in the range 71.8-114.8 kJ mol-1. A mechanism involving surface-bound amido, imido, nitrido, hydrido, methylene and methyl species is proposed to account for the major and minor products. C1 NASA,LOCKHEED ENGN & SCI CO,WHITE SANDS TEST FACIL,LAS CRUCES,NM 88004. RP DAVIS, DD (reprint author), NEW MEXICO STATE UNIV,DEPT CHEM,LAS CRUCES,NM 88003, USA. NR 23 TC 1 Z9 1 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-6031 J9 THERMOCHIM ACTA JI Thermochim. Acta PD MAR 15 PY 1991 VL 175 IS 2 BP 189 EP 198 DI 10.1016/0040-6031(91)80065-Q PG 10 WC Thermodynamics; Chemistry, Analytical; Chemistry, Physical SC Thermodynamics; Chemistry GA FE279 UT WOS:A1991FE27900007 ER PT J AU LEE, RQ TALTY, T LEE, KF AF LEE, RQ TALTY, T LEE, KF TI MUTUAL COUPLING BETWEEN ELECTROMAGNETICALLY COUPLED RECTANGULAR PATCH ANTENNAS SO ELECTRONICS LETTERS LA English DT Article DE ANTENNAS AB The mutual coupling between two electromagnetically coupled rectangular patch antennas was experimentally investigated. Results are given for both radiating edge (E-plane) coupling and nonradiating edge (H-plane) coupling and for wideband as well as high gain regions. C1 UNIV TOLEDO,DEPT ELECT ENGN,TOLEDO,OH 43606. RP LEE, RQ (reprint author), NASA,LEWIS RES CTR,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 3 TC 3 Z9 3 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD MAR 14 PY 1991 VL 27 IS 6 BP 532 EP 533 DI 10.1049/el:19910335 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA FD312 UT WOS:A1991FD31200033 ER PT J AU SIMONS, RN LEE, RQ LINDAMOOD, GR AF SIMONS, RN LEE, RQ LINDAMOOD, GR TI NEW COPLANAR WAVE-GUIDE STRIPLINE FEED NETWORK FOR 7 PATCH HEXAGONAL CP SUBARRAY SO ELECTRONICS LETTERS LA English DT Article DE WAVE-GUIDES; STRIPLINES AND STRIPLINE COMPONENTS; ANTENNAS AB A novel CPW-to-stripline post coupler is demonstrated. This device couples the output power from a coax-to-CPW inphase seven-way radial power divider to a balanced stripline line stretcher and together forms a multilayer probe-type feed network. The feed network excites a seven patch hexagonal circularly polarised (CP) subarray. The measured return loss and insertion loss of the coupler are better than 17 dB and 0.25 dB at the design frequency of 2.875 GHz. The measured on-axis axial ratio for the left hand circular polarisation (LHCP) is 1.5 dB and the 3 dB beam widths are 36-degrees in the principal planes of the subarray. The gain of the subarray is 13 dB. The input return loss of the subarray is better than 10 dB. RP SIMONS, RN (reprint author), NASA,LEWIS RES CTR,MAIL STOP 54-5,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 3 TC 2 Z9 2 U1 0 U2 1 PU IEE-INST ELEC ENG PI HERTFORD PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTFORD, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD MAR 14 PY 1991 VL 27 IS 6 BP 533 EP 535 DI 10.1049/el:19910336 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA FD312 UT WOS:A1991FD31200034 ER PT J AU ANDERSEN, LJ ANDERSEN, JL THRASHER, TN KEIL, LC RAMSAY, DJ AF ANDERSEN, LJ ANDERSEN, JL THRASHER, TN KEIL, LC RAMSAY, DJ TI EFFECT OF ELEVATING LEFT HEART PRESSURE ON PLASMA VASOPRESSIN (AVP) IN DOGS WITH ARTERIAL-HYPOTENSION SO FASEB JOURNAL LA English DT Meeting Abstract C1 UNIV CALIF SAN FRANCISCO,DEPT PHYSIOL,SAN FRANCISCO,CA 94143. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 11 PY 1991 VL 5 IS 4 BP A373 EP A373 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA FC207 UT WOS:A1991FC20700016 ER PT J AU SEAQUIST, ER ODEGARD, N AF SEAQUIST, ER ODEGARD, N TI A NONTHERMAL RADIO HALO SURROUNDING M82 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES INDIVIDUAL (M82); GALAXIES STRUCTURE; RADIATION MECHANISMS; RADIO SOURCES GALAXIES ID LARGE-SCALE WINDS; STARBURST GALAXIES; IONIZED-GAS; NGC 253; NUCLEUS; PROPAGATION; DISCOVERY; ELECTRONS AB We report radio observations of the starburst galaxy M82 at several wavelengths between 90 and 6 cm. These observations reveal an extensive synchrotron-emitting halo which extends to a diameter of at least 8 kpc. The halo is interpreted in terms of synchrotron-emitting electrons swept outward from the nuclear region by the outflow probably associated with supernova activity. The brightness distribution of the halo is asymmetric, which could be related to either a corresponding asymmetry in the distribution of SNR with respect to the disk, or to the influence of the IGM through which M82 is moving. The spectral index of the emissions is -0.4 +/- 0.1 in the nucleus, steepening to about -1.0 at a radius of 1 kpc along the minor axis. We interpret this result in terms of inverse Compton scattering of the relativistic electrons against IR photons emitted by the nuclear region. There is insufficient power radiated by this mechanism however to contribute significantly to the X-ray halo seen in this galaxy. The wind speed estimate from the inverse Compton argument falls in the range 1000-3000 km s-1. The relativistic particle energy transported outward by the wind is estimated to be approximately 10(40) ergs s-1, or about 2% of the total energy transported in the wind. This result is consistent with the corresponding ratio in SNR, as expected if the wind and relativistic particles originate with the supernova activity in the nucleus. C1 NASA,GODDARD SPACE FLIGHT CTR,GEN SCI CORP,GREENBELT,MD 20771. RP SEAQUIST, ER (reprint author), UNIV TORONTO,DEPT ASTRON,TORONTO M5S 1A7,ONTARIO,CANADA. NR 35 TC 81 Z9 81 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 MAR 10 PY 1991 VL 369 IS 2 BP 320 EP 330 DI 10.1086/169764 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY637 UT WOS:A1991EY63700006 ER PT J AU MacLow, MM VANBUREN, D WOOD, DOS CHURCHWELL, E AF MacLow, MM VANBUREN, D WOOD, DOS CHURCHWELL, E TI BOW SHOCK-MODELS OF ULTRACOMPACT H-II REGIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INTERSTELLAR MOLECULES; NEBULAE H-II REGIONS; SHOCK WAVES; STARS WINDS ID EARLY-TYPE STARS; MASS-LOSS; BUBBLES; CLOUDS AB We present models of ultracompact H II regions as the bow shocks formed by massive stars, with strong stellar winds, moving supersonically through molecular clouds. The morphologies, sizes, and brightnesses of observed objects match our models well. We provide plausible models for the ultracompact H II regions G12.21-0.1, G29.96-0.02, G34.26 + 0.15, and G43.89-0.78. To do this we begin by calculating the equilibrium shape of the wind-blown shell, assuming momentum conservation. Then we illuminate the shell with ionizing radiation from the central star, perform radiative transfer for free-free emission through the shell, and visualize the resulting object at various angles for comparison with radio continuum maps. Our model unifies most of the observed morphologies of ultracompact H II regions, excluding only those objects with spherical shells. Ram pressure confinement greatly lengthens the life of ultracompact H II regions, explaining the large number that exist in the Galaxy despite their low apparent kinematic ages. C1 NATL INST STAND & TECHNOL, BOULDER, CO USA. UNIV COLORADO, JOINT INST LAB ASTROPHYS, BOULDER, CO 80309 USA. CALTECH, JET PROP LAB, CTR INFRARED PROC & ANAL, PASADENA, CA 91109 USA. HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. UNIV WISCONSIN, WASHBURN OBSERV, MADISON, WI 53706 USA. RP MacLow, MM (reprint author), NASA, AMES RES CTR, DIV SPACE SCI, MAIL STOP 245-3, MOFFETT FIELD, CA 94035 USA. OI Mac Low, Mordecai-Mark/0000-0003-0064-4060 NR 31 TC 128 Z9 128 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 MAR 10 PY 1991 VL 369 IS 2 BP 395 EP 409 DI 10.1086/169769 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY637 UT WOS:A1991EY63700011 ER PT J AU ULMER, MP PURCELL, WR WHEATON, WA MAHONEY, WA AF ULMER, MP PURCELL, WR WHEATON, WA MAHONEY, WA TI HEAO-3 UPPER LIMITS TO PULSED GAMMA-RAY EMISSION FROM PSR-1509-58 AND PSR-0833-45 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA-RAYS BURSTS; PULSARS; STARS INDIVIDUAL (PSR-1509-58, PSR-0833-45) ID X-RAY; TIMING OBSERVATIONS; VELA PULSAR; CRAB PULSAR; RADIATION AB We report upper limits to the 50 keV-10 MeV gamma-ray pulsations from PSR 1509-58 and PSR 0833-45 (Vela) made with the HEAO 3 gamma-ray spectrometer. The 2-sigma upper limit to the 50-300 keV flux from PSR 1509-58 is 6.9 x 10(-6) photons cm-2 s-1 keV-1. Combined with the best-fit X-ray spectrum, this limit suggests there is a break in the spectrum below approximately 100 keV. This upper limit is not stringent enough, however, to distinguish between thermal and nonthermal models for the source of the X-ray emission. The 2-sigma upper limit to the 3.2-10 MeV flux from PSR 0833-45 is 4.9 x 10(-8) photons cm-2 s-1 keV-1. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ULMER, MP (reprint author), NORTHWESTERN UNIV,DEPT PHYS & ASTRON,EVANSTON,IL 60208, USA. NR 28 TC 11 Z9 11 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 1991 VL 369 IS 2 BP 485 EP 489 DI 10.1086/169778 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY637 UT WOS:A1991EY63700020 ER PT J AU ROUNTREE, J SONNEBORN, G AF ROUNTREE, J SONNEBORN, G TI CRITERIA FOR THE SPECTRAL CLASSIFICATION OF B-STARS IN THE ULTRAVIOLET SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS EARLY-TYPE; STARS SPECTRAL CLASSIFICATION; ULTRAVIOLET SPECTRA ID O-STARS; RESONANCE LINES; STELLAR WINDS; SI-IV; MORPHOLOGY; DEPENDENCE; SEQUENCE; SILICON AB We have developed a set of criteria for the classification of B stars from ultraviolet spectra alone, using MK standards drawn from the optical region. The observational material consists of archival high-dispersion spectra obtained by the SWP camera on the IUE spacecraft. The spectra were resampled to a resolution of 0.25 angstrom, normalized, and plotted on a uniform scale of 10 angstrom cm-1. Approximately 100 stars having normal MK spectral types in the range B0-B8, III-V, have been classified. Only photospheric absorption lines were used as classification criteria; the Si II and Si III spectra were found to be particularly useful. The C IV, Si IV, and N V lines, which in early B stars originate in the stellar wind, were not used in the two-dimensional spectral type/luminosity classification, but the appearance of these stellar wind lines was compared with the corresponding lines in the standard stars, and some anomalies were noted. On the whole, the ultraviolet spectral types are very consistent with the optical MK types, implying that it is possible to do two-dimensional spectral classification in the ultraviolet without any knowledge of the optical spectrum. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NR 37 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 1991 VL 369 IS 2 BP 515 EP 528 DI 10.1086/169781 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY637 UT WOS:A1991EY63700023 ER PT J AU RONAN, RS HARVEY, JW DUVALL, TL AF RONAN, RS HARVEY, JW DUVALL, TL TI WAVELENGTH VARIATION OF P-MODE INTENSITY FLUCTUATIONS SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN ATMOSPHERE; SUN OSCILLATIONS ID VERTICAL PROPAGATION; SOLAR ATMOSPHERE; PHASE DELAYS; OSCILLATIONS; VELOCITY; WAVES AB We measure the oscillatory signal in the solar p-mode band as a function of optical wavelength using a grating spectrometer and Fourier transform spectrometer. Two separate regions of the spectrum are studied, 23,600-26,085 cm-1 and 14,700-15,060 cm-1. In the blue region we find that the magnitude of relative intensity fluctuations in the p-mode band is found to increase rapidly with decreasing mean spectral intensity and increasing height in the solar photosphere. The absolute magnitude of p-mode intensity oscillations is observed to decrease with decreasing spectral intensity. We find that two absorption lines in the Balmer series of hydrogen (H-gamma and H-delta) have diminished amplitudes of relative intensity oscillations in the p-mode band compared to other solar absorption lines of similar strength. We also discover that these two lines as well as Ca II H and K lines have absolute intensity fluctuations in the p-mode band which are 50% less than the absolute intensity fluctuations of the nearby continuum spectral regions. We comment on the applicability of this finding to spectrophotometric asteroseismological observations. Throughout the red spectral region, recorded at high spectral resolution, we detect an asymmetry in the intensity oscillations of the p-mode band across the line profiles of all the spectral lines in the region. The p-mode intensity oscillations are strongest in the blue wings of these lines. This is consistent with the stronger gradient dI/d-lambda in the blue wings of solar photospheric spectrum lines. We find no significant phase differences between the p-mode Doppler shifts of the various photospheric and chromospheric lines in the blue spectral region. The p-mode intensity oscillations in the lines of both the blue and red spectral regions generally lead p-mode blueward Doppler shifts by one-fourth cycle. This is consistent with the description of p-modes in the photosphere and up to the chromosphere as adiabatic, evanescent acoustic waves. C1 NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,TUCSON,AZ 85726. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP RONAN, RS (reprint author), UNIV HAWAII MANOA,INST ASTRON,2680 WOODLAWN DR,HONOLULU,HI 96822, USA. RI Duvall, Thomas/C-9998-2012 NR 24 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 MAR 10 PY 1991 VL 369 IS 2 BP 549 EP 556 DI 10.1086/169784 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY637 UT WOS:A1991EY63700026 ER PT J AU HESTER, JJ GILMOZZI, R ODELL, CR FABER, SM CAMPBELL, B CODE, A CURRIE, DG DANIELSON, GE EWALD, SP GROTH, EJ HOLTZMAN, JA KELSALL, T LAUER, TR LIGHT, RM LYNDS, R ONEIL, EJ SHAYA, EJ WESTPHAL, JA AF HESTER, JJ GILMOZZI, R ODELL, CR FABER, SM CAMPBELL, B CODE, A CURRIE, DG DANIELSON, GE EWALD, SP GROTH, EJ HOLTZMAN, JA KELSALL, T LAUER, TR LIGHT, RM LYNDS, R ONEIL, EJ SHAYA, EJ WESTPHAL, JA TI IONIZATION FRONTS AND SHOCKED FLOWS - THE STRUCTURE OF THE ORION NEBULA AT 0''.1 SO ASTROPHYSICAL JOURNAL LA English DT Article DE NEBULAE, ORION NEBULA; NEBULAE, STRUCTURE; STARS, FORMATION ID HERBIG-HARO OBJECTS; CONTINUUM RADIO-SOURCES; MOLECULAR-HYDROGEN; EMISSION; REGIONS; MODEL; M42; GAS AB We present HST Wide-Field Camera images of a field in the Orion Nebula obtained in emission from [S II], H-beta, and [O II]. The morphology of the [S II] emission is markedly different from the other lines. While H-beta and [O II] are distributed fairly smoothly, [S II] is dominated by filamentary features with widths between 0.1" and 1" which sharply highlight ionization fronts moving into dense neutral material. These photoionization fronts act as probes of the structure of the cavity walls of this blister H II region. Their morphology indicates that while the surfaces into which they are moving are textured, subarcsecond clumps with high density contrast are uncommon. An exception is a bow shock-shaped ionization front seen along the face of a solar system-sized (0.6" = 270 AU) clump which is itself seen in extinction. The field contains a number of HH objects and related structures, many of which were previously recognized as such, but whose complex structure is revealed here by the resolution of HST. These include M42 HH 1, which is seen to be an intricate structure of knots and filaments with a head-tail morphology. M42 HH 2 shows structure from both the shocked cavity walls and the shocked atomic outflow. M42 HH 5-7 break into numerous condensations with an appearance reminiscent of HH 7-11. All objects with a bow shock-shaped structure (i.e., M42 HH 1, 5, 7, and 10) show enhanced H-beta emission at the apex of the structure where the shock should be strongest. M42 HH 8 and 9 may be HH objects viewed face-on, or alternatively condensations photoionized by a nearby A or B star. Emission from [S II] traces shocks at the walls of an ionized jet apparently emanating from a star in a dark cloud. This cloud seen in extinction is coincident with H-2 Peak 1, which we propose is on the near side of the nebula. C1 SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. EUROPEAN SPACE AGCY,DEPT SPACE SCI,DIV ASTROPHYS,2200 AG NOORDWIJK,NETHERLANDS. RICE UNIV,DEPT SPACE PHYS & ASTRON,HOUSTON,TX 77251. UNIV CALIF SANTA CRUZ,LICK OBSERV,BOARD STUDIES ASTRON & ASTROPHYS,SANTA CRUZ,CA 95064. UNIV NEW MEXICO,DEPT PHYS,ALBUQUERQUE,NM 87136. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV MARYLAND,DEPT PHYS & ASTRON,COLLEGE PK,MD 20742. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. LOWELL OBSERV,FLAGSTAFF,AZ 86001. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. RP HESTER, JJ (reprint author), CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125, USA. NR 29 TC 30 Z9 30 U1 0 U2 3 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 1991 VL 369 IS 2 BP L75 EP & DI 10.1086/185962 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY641 UT WOS:A1991EY64100013 ER PT J AU HOLTZMAN, JA GROTH, EJ LIGHT, RM FABER, SM HUNTER, D ONEIL, EJ SHAYA, EJ BAUM, WA CAMPBELL, B CODE, A CURRIE, DG EWALD, SP HESTER, JJ KELSALL, T LAUER, TR LYNDS, R SCHNEIDER, DP SEIDELMANN, PK WESTPHAL, JA AF HOLTZMAN, JA GROTH, EJ LIGHT, RM FABER, SM HUNTER, D ONEIL, EJ SHAYA, EJ BAUM, WA CAMPBELL, B CODE, A CURRIE, DG EWALD, SP HESTER, JJ KELSALL, T LAUER, TR LYNDS, R SCHNEIDER, DP SEIDELMANN, PK WESTPHAL, JA TI STELLAR PHOTOMETRY WITH THE HUBBLE SPACE TELESCOPE WIDE-FIELD PLANETARY CAMERA - A PROGRESS REPORT SO ASTROPHYSICAL JOURNAL LA English DT Article DE IMAGE PROCESSING; PHOTOMETRY ID IMAGES AB We describe the prospects for the use of the Wide-Field/Planetary Camera (WFPC) for stellar photometry. The large halos of the point-spread function (PSF) resulting from spherical aberration and from spatial, temporal, and color variations of the PSF are the main limitations to accurate photometry. Degradations caused by crowding are exacerbated by the halos of the PSF. Here we attempt to quantify these effects and determine the current accuracy of stellar photometry with the WFPC. In realistic cases, the brighter stars in crowded fields have 0.09 mag errors; fainter stars have larger errors depending on the degree of crowding. We find that measuring Cepheids in Virgo Cluster galaxies is not currently possible without inordinate increases in exposure times. C1 PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. UNIV CALIF SANTA CRUZ,LICK OBSERV,BOARD STUDIES ASTRON & ASTROPHYS,SANTA CRUZ,CA 95064. NATL OPT ASTRON OBSERV,TUCSON,AZ 85726. UNIV MARYLAND,DEPT PHYS & ASTRON,COLLEGE PK,MD 20742. UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98105. UNIV NEW MEXICO,DEPT PHYS,ALBUQUERQUE,NM 87131. UNIV WISCONSIN,WASHBURN OBSERV,MADISON,WI 53706. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. INST ADV STUDY,PRINCETON,NJ 08540. USN OBSERV,NATL ALMANAC OFF,WASHINGTON,DC 20390. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP HOLTZMAN, JA (reprint author), LOWELL OBSERV,1400 W MARS HILL RD,FLAGSTAFF,AZ 86001, USA. NR 15 TC 29 Z9 29 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 MAR 10 PY 1991 VL 369 IS 2 BP L35 EP & DI 10.1086/185953 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY641 UT WOS:A1991EY64100004 ER PT J AU LAUER, TR FABER, SM HOLTZMAN, JA BAUM, WA CURRIE, DG EWALD, SP GROTH, EJ HESTER, JJ KELSALL, T KRISTIAN, J LIGHT, RM LYNDS, CR ONEIL, EJ SHAYA, EJ WESTPHAL, JA AF LAUER, TR FABER, SM HOLTZMAN, JA BAUM, WA CURRIE, DG EWALD, SP GROTH, EJ HESTER, JJ KELSALL, T KRISTIAN, J LIGHT, RM LYNDS, CR ONEIL, EJ SHAYA, EJ WESTPHAL, JA TI THE CORE OF THE NEARBY SO GALAXY NGC-7457 IMAGED WITH THE HST PLANETARY CAMERA SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, NUCLEI; GALAXIES, PHOTOMETRY; GALAXIES, STRUCTURE ID ELLIPTICAL GALAXIES; VELOCITY DISPERSIONS; DISTRIBUTIONS AB We have observed the nearby S0 galaxy NGC 7457 with the Planetary Camera of the Hubble Space Telescope. Spatial structure is observable at the diffraction-limited resolution of the 2.4 m HST primary despite the effects of spherical aberration. The central distribution of starlight appears consistent with a gamma almost-equal-to -1.0 power law for r < 600 pc, plus a possible additional stellar nucleus with L approximately 1 x 10(7) L. (V band). We find no evidence of a core to limits r(c) < 0.052" = 3.4 pc (H0 = 80 km s-1 Mpc-1), in contrast to a priori estimates of r(c) almost-equal-to 30 pc based on total galaxy luminosity. The center of NGC 7457 remains unresolved at HST resolution and has a central luminosity density rho-0 > 3 x 10(4) L. pc-3 (V band). This is now the second densest core known after M32. From the ground, NGC 7457 resembles any number of unresolved elliptical galaxies, which suggests that compact dense cores may be common. The images of NGC 7457 demonstrate that HST can still provide unique and astrophysically interesting information on the central structure of galaxies. C1 UNIV CALIF SANTA CRUZ,LICK OBSERV,BOARD STUDIES ASTRON & ASTROPHYS,SANTA CRUZ,CA 95064. LOWELL OBSERV,FLAGSTAFF,AZ. UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98195. UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. CARNEGIE INST WASHINGTON,OBSERV,PASADENA,CA 91101. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP LAUER, TR (reprint author), NATL OPT ASTRON OBSERV,POB 26732,TUCSON,AZ 85726, USA. NR 20 TC 55 Z9 55 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 MAR 10 PY 1991 VL 369 IS 2 BP L41 EP L44 DI 10.1086/185954 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY641 UT WOS:A1991EY64100005 ER PT J AU LAUER, TR HOLTZMAN, JA FABER, SM BAUM, WA CURRIE, DG EWALD, SP GROTH, EJ HESTER, JJ KELSALL, T LIGHT, RM LYNDS, CR ONEIL, EJ SCHNEIDER, DP SHAYA, EJ WESTPHAL, JA AF LAUER, TR HOLTZMAN, JA FABER, SM BAUM, WA CURRIE, DG EWALD, SP GROTH, EJ HESTER, JJ KELSALL, T LIGHT, RM LYNDS, CR ONEIL, EJ SCHNEIDER, DP SHAYA, EJ WESTPHAL, JA TI THE POSTCOLLAPSE CORE OF M15 IMAGED WITH THE HST PLANETARY CAMERA SO ASTROPHYSICAL JOURNAL LA English DT Article DE CLUSTERS, DYNAMICS; CLUSTERS, GLOBULAR ID GLOBULAR-CLUSTER M15; CCD PHOTOMETRY AB We have obtained U-band images of the M15 core with the Planetary Camera of the Hubble Space Telescope. We are able to resolve stars down to the main-sequence turnoff (m(U) almost-equal-to 19.4) into the cluster center. We use crowded field photometry techniques to decompose M15 into bright resolved stars and a residual component consisting of stars at turnoff brightness or fainter. The residual component comprises 59% of the cluster light and follows a gamma = -0.71 power-law distribution for r > 1". The residual component flattens off interior to this radius and has a large core with r(c) = 2.2" = 0.13 pc. The core size may reflect postcollapse core expansion. The resolved stars have a slightly shallower distribution (gamma = -0.53) but have an abrupt over-density for r < 1.5", which accounts for the unresolved surface brightness cusp at ground resolution. The bright stars do not become more highly concentrated at still smaller radii, however; neither the bright stars nor the residual component form a cusp at subarcsecond resolution. The total central density of light in all components is 8 x 10(5) L. pc-3 (U-band). The Peterson, Seitzer, and Cudworth central velocity dispersion implies a high core M/L almost-equal-to 8 (U-band). The existence of a core rather than a cusp at the 0.1 pc scale may imply that the centrally deduced dark matter is in a diffuse form rather than a massive black hole. C1 LOWELL OBSERV,FLAGSTAFF,AZ 86001. UNIV CALIF SANTA CRUZ,LICK OBSERV,BOARD STUDIES ASTRON & ASTROPHYS,SANTA CRUZ,CA 95064. UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98195. UNIV MARYLAND,DEPT PHYS & ASTRON,COLLEGE PK,MD 20742. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. PRINCETON UNIV,DEPT PHYS,PRINCETON,NJ 08544. CALTECH,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. INST ADV STUDY,SCH NAT SCI,PRINCETON,NJ 08590. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. RP LAUER, TR (reprint author), NATL OPT ASTRON OBSERV,POB 26732,TUCSON,AZ 85726, USA. NR 26 TC 59 Z9 59 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 MAR 10 PY 1991 VL 369 IS 2 BP L45 EP & DI 10.1086/185955 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY641 UT WOS:A1991EY64100006 ER PT J AU LEE, TJ RENDELL, AP AF LEE, TJ RENDELL, AP TI THE STRUCTURE AND ENERGETICS OF THE HCN-]HNC TRANSITION-STATE SO CHEMICAL PHYSICS LETTERS LA English DT Article ID MOLECULAR ELECTRONIC-STRUCTURE; POTENTIAL-ENERGY SURFACE; GAUSSIAN BASIS FUNCTIONS; HNC REVERSIBLE HCN; ATOMIC BASIS SETS; FIRST-ROW ATOMS; HYDROGEN ISOCYANIDE; VIBRATIONAL-STATES; CONTRACTION; ABINITIO AB The optimum geometries and quadratic force constants of HCN, HNC and the transition state connecting them have been determined at the single and double excitation coupled-cluster (CCSD) and CCSD(T) levels of theory. Energy differences were evaluated using the CCSD and CCSD(T) methods in conjunction with large atomic natural orbital basis sets containing g-type basis functions on the heavy atoms and f-type functions on hydrogen. The most reliable structure obtained for the transition state has bond distances of 1.194, 1.188 and 1.389 angstrom for r(CN), r(CH) and r(NH), respectively. Including a correction for zero-point vibrational energies, the transition state is predicted to be 44.6 +/- 1.0 kcal/mol above the HCN isomer, while HNC is predicted to be 14.4 +/- 1.0 kcal/mol above HCN. The latter value is in excellent agreement with the most recent experimental determination (14.8 +/- 2.0 kcal/mol). RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Rendell, Alistair/A-4883-2008; Lee, Timothy/K-2838-2012 OI Rendell, Alistair/0000-0002-9445-0146; NR 48 TC 102 Z9 102 U1 0 U2 7 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 MAR 8 PY 1991 VL 177 IS 6 BP 491 EP 497 DI 10.1016/0009-2614(91)90073-I PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FC800 UT WOS:A1991FC80000001 ER PT J AU HENSLEY, JM GREEN, S FLYNN, GW AF HENSLEY, JM GREEN, S FLYNN, GW TI A SIMPLE ABINITIO CALCULATION FOR ENERGY-TRANSFER IN COLLISIONS OF HOT HYDROGEN-ATOMS WITH CARBON-DIOXIDE SO CHEMICAL PHYSICS LETTERS LA English DT Article ID EXCIMER LASER PHOTOLYSIS; VIBRATIONAL-EXCITATION; TRIATOMIC-MOLECULES; HE ATOMS; CO2; SPECTROSCOPY; RELAXATION; QUANTUM; HELIUM; PROBE AB Cross sections for excitation of the CO2v3 asymmetric stretch vibration in collisions with 2.1 eV hydrogen atoms have been calculated within the vibrational close coupling rotational infinite order sudden (VCC-IOS) approximation. The intermolecular potential was assumed to be a pairwise additive atom-atom exponential repulsion with parameters fitted to theoretical SCF points. Predicted final rotational state distributions agree reasonably well with experimental data, as well as with predictions of a recently proposed breathing ellipsoid model. Predicted vibrational excitation rates, however, are one to two orders of magnitude too small, a failure which is attributed to the inability of a pairwise additive form to reproduce accurately the vibrational dependence of the potential. C1 COLUMBIA UNIV,DEPT CHEM,NEW YORK,NY 10027. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,GREENBELT,MD 20771. COLUMBIA UNIV,COLUMBIA RADIAT LAB,NEW YORK,NY 10027. NR 35 TC 2 Z9 2 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 MAR 8 PY 1991 VL 177 IS 6 BP 508 EP 516 DI 10.1016/0009-2614(91)90076-L PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FC800 UT WOS:A1991FC80000004 ER PT J AU ZAHOPOULOS, C SRIDHAR, S BAUTISTA, JJ ORTIZ, G LANAGAN, M AF ZAHOPOULOS, C SRIDHAR, S BAUTISTA, JJ ORTIZ, G LANAGAN, M TI PERFORMANCE OF A HIGH-TC SUPERCONDUCTING ULTRALOW-LOSS MICROWAVE STRIPLINE FILTER SO APPLIED PHYSICS LETTERS LA English DT Article AB We report the successful fabrication of a five-pole interdigital stripline filter made of the 93 K superconductor Y1Ba2Cu3O(y) coated on a silver substrate, with a center frequency of 8.5 GHz and an extremely high rejection ratio of 80 dB. The lowest insertion loss measured was 0.1 dB at 12 K, with a return loss better than 16 dB, representing significant improvements over a similar Cu filter, and comparable to low T(c) filters. The insertion loss appears to be limited by extrinsic factors such as tuning mismatch and joint losses, and not by the superconducting material losses. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. ARGONNE NATL LAB,ARGONNE,IL 60439. RP ZAHOPOULOS, C (reprint author), NORTHEASTERN UNIV,DEPT PHYS,BOSTON,MA 02115, USA. RI Sridhar, Srinivas/A-3688-2012 NR 9 TC 14 Z9 14 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD MAR 4 PY 1991 VL 58 IS 9 BP 977 EP 979 DI 10.1063/1.104461 PG 3 WC Physics, Applied SC Physics GA FA938 UT WOS:A1991FA93800035 ER PT J AU FLETCHER, CH FAIRBRIDGE, RH MOLLER, JK LONG, AJ AF FLETCHER, CH FAIRBRIDGE, RH MOLLER, JK LONG, AJ TI WARM TO COLD POLAR CLIMATE TRANSITIONS OVER THE LAST 15,000 YEARS - A PALEOCLIMATOLOGY RECORD FROM THE RAISED BEACHES OF NORTHERN NORWAY SO AAPG BULLETIN-AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS LA English DT Meeting Abstract C1 UNIV HAWAII,HONOLULU,HI 96822. NASA,GODDARD SPACE FLIGHT CTR,GODDARD INST SPACE STUDIES,GREENBELT,MD 20771. UNIV TROMSO,N-9001 TROMSO,NORWAY. UNIV DURHAM,DURHAM DH1 3HP,ENGLAND. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER ASSN PETROL GEOLOGISTS PI TULSA PA 1444 S BOULDER AVE PO BOX 979, TULSA, OK 74101 SN 0149-1423 J9 AAPG BULL JI AAPG Bull.-Am. Assoc. Petr. Geol. PD MAR PY 1991 VL 75 IS 3 BP 575 EP 575 PG 1 WC Geosciences, Multidisciplinary SC Geology GA FA437 UT WOS:A1991FA43700200 ER PT J AU DARWIN, CR AUSTIN, G VARNADO, L EUDY, G AF DARWIN, CR AUSTIN, G VARNADO, L EUDY, G TI A VIEW TOWARD FUTURE LAUNCH VEHICLES - A CIVIL PERSPECTIVE SO ACTA ASTRONAUTICA LA English DT Article AB New launch capabilities are needed to support the evolving U.S. civil space activities. Requirements are materializing for unmanned cargo vehicles and manned systems to effectively support a balanced aggressive space activity, including the Space Station Freedom and planetary exploration. Needs include larger lift, better assured access, lower operating costs, and operating flexibility. The set of logical, complementing new cargo vehicles are a mid-1990s Shuttle cargo vehicle for delivery of 45,400-68,000 kg (100 K-150 K lb) to low Earth orbit (LEO) with limited flight rates; the modular Advanced Launch System with 45,000-90,700 kg (100 K-200 K lb) by the year 2000, and a very large heavy lift capability system of 90,700-181,400 kg (200 K-400 K lb) by 2010. Manned access must be sustained and broadened by improvements to the Space Shuttle operations, the use of a personnel launch vehicle in the late 1990s, and consideration of a Space Shuttle replacement in 2005-2015. Designs must and are embracing modularity, ruggedness, recoverability, new manufacturing techniques, and selected technologies to achieve necessary reliabilities, operability, and cost effectiveness. The result is a logical time-phased integrated set of effective capabilities. RP DARWIN, CR (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD MAR PY 1991 VL 25 IS 3 BP 165 EP 175 DI 10.1016/0094-5765(91)90144-T PG 11 WC Engineering, Aerospace SC Engineering GA FR968 UT WOS:A1991FR96800006 ER PT J AU BATINA, JT AF BATINA, JT TI UNSTEADY EULER ALGORITHM WITH UNSTRUCTURED DYNAMIC MESH FOR COMPLEX-AIRCRAFT AERODYNAMIC ANALYSIS SO AIAA JOURNAL LA English DT Article ID FIGHTER-LIKE CONFIGURATION; EQUATIONS; FLOW AB An Euler solution algorithm is presented for unsteady aerodynamic analysis of complex-aircraft configurations. The flow solver involves a multistage Runge-Kutta time-stepping scheme that uses a finite-volume spatial discretization on an unstructured grid made up of tetrahedra. A significant contribution of the research is the development and implementation of a moving mesh algorithm that is employed for problems involving static or dynamic deformation of the aircraft. The mesh algorithm is a general procedure that can treat realistic motions and deformations of complex-aircraft configurations. Steady and unsteady results are presented for a supersonic fighter configuration to demonstrate applications of the Euler solver and dynamic mesh algorithm. The unsteady flow results were obtained for the aircraft oscillating harmonically in a complete-vehicle bending mode. Effects of angle of attack and reduced frequency on instantaneous pressures and force responses were investigated. The paper presents descriptions of the Euler solver and dynamic mesh algorithm along with results that assess the capability. RP BATINA, JT (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 17 TC 105 Z9 121 U1 2 U2 6 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 MAR PY 1991 VL 29 IS 3 BP 327 EP 333 DI 10.2514/3.10583 PG 7 WC Engineering, Aerospace SC Engineering GA FE873 UT WOS:A1991FE87300002 ER PT J AU DEGANI, D SCHIFF, LB AF DEGANI, D SCHIFF, LB TI NUMERICAL-SIMULATION OF THE EFFECT OF SPATIAL DISTURBANCES ON VORTEX ASYMMETRY SO AIAA JOURNAL LA English DT Article ID CYLINDER AB The steady asymmetric vortex pattern observed on slender bodies of revolution at large angle of attack was investigated using fine-grid, thin-layer Navier-Stokes computations. The computed results demonstrate, for the first time, the marked asymmetry that has been observed in experiments. To obtain asymmetry, it was found essential to introduce a space-fixed, time-invariant perturbation into the computation. If the perturbation was removed, the asymmetric flow returned toward symmetry. The perturbations were found to be more effective when located close to the nose. Taken together with the experimental observations, the computational results suggest that vortex asymmetry is forced by amplification of small distrubances, such as those due to surface roughness, occurring within the body viscous boundary layer. C1 TECHNION ISRAEL INST TECHNOL,FAC MECH ENGN,HAIFA,ISRAEL. RP DEGANI, D (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 25 TC 26 Z9 27 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 MAR PY 1991 VL 29 IS 3 BP 344 EP 352 DI 10.2514/3.10585 PG 9 WC Engineering, Aerospace SC Engineering GA FE873 UT WOS:A1991FE87300004 ER PT J AU BARNWELL, RW WAHLS, RA AF BARNWELL, RW WAHLS, RA TI SKIN FRICTION LAW FOR COMPRESSIBLE TURBULENT-FLOW SO AIAA JOURNAL LA English DT Article AB An algebraic skin-friction law is derived for adiabatic, compressible, equilibrium, turbulent boundary-layer flow. An outer solution in terms of the Clauser defect stream function is joined to an inner empirical expression composed of compressible laws of the wall and wake. The modified Crocco temperature-velocity relationship and the Clauser eddy viscosity model are used in the outer solution. The skin-friction law pertains for all pressure gradients in the incompressible through supersonic range and for small pressure gradients in the hypersonic range. Excellent comparisons with experiment are obtained in the appropriate parameter ranges. C1 VIGYAN INC,HAMPTON,VA 23666. RP BARNWELL, RW (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 14 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 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 1991 VL 29 IS 3 BP 380 EP 386 DI 10.2514/3.10589 PG 7 WC Engineering, Aerospace SC Engineering GA FE873 UT WOS:A1991FE87300008 ER PT J AU PRITCHARD, JI ADELMAN, HM AF PRITCHARD, JI ADELMAN, HM TI DIFFERENTIAL-EQUATION BASED METHOD FOR ACCURATE MODAL APPROXIMATIONS SO AIAA JOURNAL LA English DT Note ID STRUCTURAL SYNTHESIS; CONSTRAINTS C1 LANGLEY RES CTR,HAMPTON,VA 23665. NASA,INTERDISCIPLINARY RES OFF,HAMPTON,VA 23665. NR 12 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 MAR PY 1991 VL 29 IS 3 BP 484 EP 486 DI 10.2514/3.10609 PG 3 WC Engineering, Aerospace SC Engineering GA FE873 UT WOS:A1991FE87300027 ER PT J AU CONVERTINO, VA ADAMS, WC AF CONVERTINO, VA ADAMS, WC TI ENHANCED VAGAL BAROREFLEX RESPONSE DURING 24 H AFTER ACUTE EXERCISE SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE BAROREFLEX SENSITIVITY; BLOOD PRESSURE; MAXIMAL EXERCISE; NECK CHAMBER; SYMPATHETIC ID BARORECEPTOR-CARDIAC REFLEX; BLOOD-PRESSURE; NOREPINEPHRINE; VASOPRESSIN; STIMULATION AB We evaluated carotid-cardiac baroreflex responses in eight normotensive men (25-41 yr) on two different test days, each separated by at least 1 wk. On one day, baroreflex response was tested before and at 3, 6, 12, 18, and 24 h after graded supine cycle exercise to volitional exhaustion. On another day, this 24-h protocol was repeated with no exercise (control). Beat-to-beat R-R intervals were measured during external application of graded pressures to the carotid sinuses from 40 to -65 mmHg; changes of R-R intervals were plotted against carotid pressure (systolic pressure minus neck chamber pressure). The maximum slope of the response relationship increased (P < 0.05) from preexercise to 12 h (3.7 +/- 0.4 to 7.1 +/- 0.7 ms/mmHg) and remained significantly elevated through 24 h. The range of the R-R response was also increased from 217 +/- 24 to 274 +/- 32 ms (P < 0.05). No significant differences were observed during the control 24-h period. An acute bout of graded exercise designed to elicit exhaustion increases the sensitivity and range of the carotid-cardiac baroreflex response for 24 h and enhances its capacity to buffer against hypotension by increasing heart rate. These results may represent an underlying mechanism that contributes to blood pressure stability after intense exercise. C1 UNIV CALIF DAVIS,DEPT PHYS EDUC,DAVIS,CA 95616. RP CONVERTINO, VA (reprint author), NASA,LIFE SCI RES OFF,MAIL CODE MD-RES-P,KENNEDY SPACE CTR,FL 32899, USA. NR 25 TC 48 Z9 48 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 MAR PY 1991 VL 260 IS 3 BP R570 EP R575 PN 2 PG 6 WC Physiology SC Physiology GA FC253 UT WOS:A1991FC25300064 PM 2001006 ER PT J AU DENNING, PJ AF DENNING, PJ TI MUTUAL EXCLUSION SO AMERICAN SCIENTIST LA English DT Article RP DENNING, PJ (reprint author), NASA,AMES RES CTR,ADV COMP SCI RES INST,MOFFETT FIELD,CA 94035, USA. NR 8 TC 1 Z9 1 U1 0 U2 0 PU SIGMA XI-SCI RES SOC PI RES TRIANGLE PK PA PO BOX 13975, RES TRIANGLE PK, NC 27709 SN 0003-0996 J9 AM SCI JI Am. Scientist PD MAR-APR PY 1991 VL 79 IS 2 BP 111 EP 114 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FL670 UT WOS:A1991FL67000006 ER PT J AU GATSKI, TB AF GATSKI, TB TI REVIEW OF INCOMPRESSIBLE FLUID-FLOW COMPUTATIONS USING THE VORTICITY VELOCITY FORMULATION SO APPLIED NUMERICAL MATHEMATICS LA English DT Review ID NAVIER-STOKES EQUATIONS; LAYERS AB An overview of the development of the vorticity-velocity formulation to the numerical solution of the Navier-Stokes equations is presented. The advantages and disadvantages to such a formulation are discussed, as well as the various numerical algorithms used in solving these governing differential equations. RP GATSKI, TB (reprint author), NASA,LANGLEY RES CTR,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23665, USA. NR 36 TC 37 Z9 38 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-9274 J9 APPL NUMER MATH JI Appl. Numer. Math. PD MAR PY 1991 VL 7 IS 3 BP 227 EP 239 DI 10.1016/0168-9274(91)90035-X PG 13 WC Mathematics, Applied SC Mathematics GA FF030 UT WOS:A1991FF03000002 ER PT J AU MERCER, CR BEHEIM, G AF MERCER, CR BEHEIM, G TI FIBER OPTIC PHASE STEPPING SYSTEM FOR INTERFEROMETRY SO APPLIED OPTICS LA English DT Article DE PHASE STEPPING; FIBER OPTICS; INTERFEROMETRY; NONDESTRUCTIVE TESTING ID HOLOGRAPHIC-INTERFEROMETRY; SHIFTING INTERFEROMETRY; DEFORMATION MEASUREMENT; SPECKLE INTERFEROMETRY; FRINGE STABILIZATION; HETERODYNE AB A closed loop phase control system using an all-fiber optical configuration has been developed for use in phase stepping interferometry. This system drives the relative phase of two interfering beams through a sequence of pi/2 rad increments so that the initial relative phase of these beams can be determined. This phase stepping system uses optical fibers to provide spatially uniform phase steps from a flexible, easily aligned optical configuration. In addition, this system uses phase feed back to eliminate phase modulator errors and to compensate for phase drifts caused by environmental disturbances. RP MERCER, CR (reprint author), NASA,LEWIS RES CTR,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 21 TC 24 Z9 25 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 1 PY 1991 VL 30 IS 7 BP 729 EP 734 PG 6 WC Optics SC Optics GA FA604 UT WOS:A1991FA60400004 PM 20582052 ER PT J AU CONTENT, D TROUT, C DAVILA, P WILSON, M AF CONTENT, D TROUT, C DAVILA, P WILSON, M TI ABERRATION CORRECTED ASPHERIC GRATINGS FOR FAR ULTRAVIOLET SPECTROGRAPHS - CONVENTIONAL APPROACH SO APPLIED OPTICS LA English DT Article DE DIFFRACTION GRATING; FAR ULTRAVIOLET SPECTROSCOPY; ABERRATION REDUCTION; VARIATE NORMAL DISTRIBUTIONS AB Two approaches to reducing optical aberrations of concave grating spectrographs have been used, holographically controlling the groove curvature and spacing and reshaping the optical substrate while ruling the grooves conventionally. The latter approach, slightly deforming an ellipsoidal grating blank, can lead to diffraction-limited performance at a single far ultraviolet wavelength. When such a grating is used in a slitted Rowland circle spectrograph, the result is an extremely efficient spectrograph with spectral resolving power of approximately 30,000 and low astigmatism. Optical fabrication technology has advanced to the point where these exotic surface gratings are becoming practical. RP CONTENT, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 18 TC 12 Z9 12 U1 0 U2 2 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD MAR 1 PY 1991 VL 30 IS 7 BP 801 EP 806 PG 6 WC Optics SC Optics GA FA604 UT WOS:A1991FA60400015 PM 20582063 ER PT J AU HALPERN, JP CHEN, VS MADEJSKI, GM CHANAN, GA AF HALPERN, JP CHEN, VS MADEJSKI, GM CHANAN, GA TI THE REDSHIFT OF THE X-RAY SELECTED BL LACERTAE OBJECT H0414+009 SO ASTRONOMICAL JOURNAL LA English DT Article AB The x-ray selected BL Lac object H0414 + 004 has a redshift of 0.287, measured from the starlight of its host galaxy. The optical spectrum is well described by the sum of a standard elliptical galaxy plus a relatively flat power law (alpha approximately 0.3). The galaxy contributes approximately 40% of the light in the spectrum in the rest-frame V band, and is one of the most luminous galaxies known (M(v) approximately - 24). The properties of H0414 + 009 are similar in all respects to a previously studied object, 1E 1415 + 259 at z = 0.237. If x-ray selected BL Lacs continue to be found in such bright galaxies, then the prospects of studying their luminosity function and evolution are considerably enhanced. There is also possible evidence for intrinsic x-ray absorption by a warm medium, as has been found in several other BL Lacs. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIVERSITIES SPACE RES ASSOC,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. UNIV CALIF IRVINE,DEPT PHYS,IRVINE,CA 92717. RP HALPERN, JP (reprint author), COLUMBIA UNIV,COLUMBIA ASTROPHYS LAB,538 W 120TH ST,NEW YORK,NY 10027, USA. NR 18 TC 17 Z9 17 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 MAR PY 1991 VL 101 IS 3 BP 818 EP 820 DI 10.1086/115725 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY997 UT WOS:A1991EY99700005 ER PT J AU CARDELLI, JA CLAYTON, GC AF CARDELLI, JA CLAYTON, GC TI ABSOLUTE EXTINCTION AND THE INFLUENCE OF ENVIRONMENT - DARK CLOUD SIGHT LINES TOWARD VCT-10, VCT-30, AND WALKER-67 SO ASTRONOMICAL JOURNAL LA English DT Article ID ULTRAVIOLET INTERSTELLAR EXTINCTION; MOLECULAR CLOUD; GRAINS; DUST; LAW AB We present absolute near-infrared, optical, and ultraviolet extinction data, A(lambda)/A(V), for the three sight lines passing through dense, dark cloud environments with large values of total-to-selective extinction, R-upsilon [= A(V)/E(B - V)]. The absolute extinction curves for VCT 10(R-upsilon = 4.3), VCT 30 (R-upsilon = 4.7), and Walker 67 (R-upsilon = 5.4) exhibit no significant deviations from the R-upsilon dependent extinction law of Cardelli et al. [ApJ, 345, 245 (1989)] from the near IR through the near UV (3.4-mu-m > lambda > 0.25-mu-m). However, for lambda less-than-or-equal-to 0.25-mu-m, all three sight lines exhibit similar and relatively large deviations from the R-upsilon dependent extinction law. The contrast of large deviations from the R-upsilon dependent extinction law for lambda less-than-or-equal-to 0.25-mu-m to strong adherence for lambda > 0.25-mu-m suggests that (1) the grains that give rise to the optical/near-IR extinction are processed in an efficient and systematic way and (2) the bump and far-UV extinction components produce little or no contribution at optical wavelengths and are modified by processes independent of those responsible for the R-upsilon dependence. In addition, we hae fitted the UV extinction data with the three component fitting techniques of Fitzpatrick and Massa and find the fitted ''0.2175-mu-m (2175 angstrom)'' bump toward VCT 10 to be very broad and shifted to a central wavelength of lambda-0 almost-equal-to 0.2120-mu-m. The UV extinction characteristics observed toward VCT 10, VCT 30, and to a smaller degree Walker 67, are similar in nature to other dark cloud sight lines which sample a large range of R-upsilon. These characteristics are in sharp contrast to sight lines associated with bright nebulosity which generally exhibit only minor deviations from the Cardelli et al. R-upsilon dependent average in the UV and some of the narrowest ''2175 angstrom'' bumps yet observed. The general form of the UV extinction deviations of the dark cloud sight lines from the R-upsilon dependent extinction law along with their sharp contrast to sight lines in regions of bright nebulosity seems consistent with the affects of coatings on both the small bump and far-UV grains. The existence of these coatings appear to be a sensitive function of the UV radiation field. C1 NASA,DIV ASTROPHYS,WASHINGTON,DC 20546. RP CARDELLI, JA (reprint author), UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706, USA. NR 50 TC 58 Z9 58 U1 0 U2 1 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 MAR PY 1991 VL 101 IS 3 BP 1021 EP 1032 DI 10.1086/115744 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY997 UT WOS:A1991EY99700024 ER PT J AU RATNATUNGA, KU CASERTANO, S AF RATNATUNGA, KU CASERTANO, S TI ABSOLUTE MAGNITUDE CALIBRATION USING TRIGONOMETRIC PARALLAX - INCOMPLETE, SPECTROSCOPIC SAMPLES SO ASTRONOMICAL JOURNAL LA English DT Article ID PROPER MOTIONS AB A new numerical algorithm is used to calibrate the absolute magnitude of spectroscopically selected stars from their observed trigonometric parallax. This procedure, based on maximum likelihood estimation, can retrieve unbiased estimates of the intrinsic absolute magnitude and its dispersion even from incomplete samples suffering from selection biases in apparent magnitude and color. It can also make full use of low accuracy and negative parallaxes and incorporate censorship on reported parallax values. Accurate error estimates are derived for each of the fitted parameters. Our algorithm allows an a posteriori check of whether the fitted model gives a good representation of the observations. An objective test is devised to detect and reject outliers within given confidence limits, and the corresponding criterion is consistently built into the evaluation of the likelihood function. The procedure is described in general and applied to both real and simulated data. From the Vyssotsky sample of K and M disk dwarfs we derive, using our method, the calibration M(v) = (10.78 +/- 0.02) + (5.86 +/- 0.07)(R - I - 1) in the Kron (R-I) color range [0.35, 1.3], with an intrinsic rms magnitude dispersion of the sequence sigma-md = 0.45+/-0.02 mag. This dispersion may be partly due to the distribution of the metallicity, which is ignored in this paper. C1 UNIV PITTSBURGH,DEPT PHYS & ASTRON,PITTSBURGH,PA 15260. RP RATNATUNGA, KU (reprint author), NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,CODE 930,GREENBELT,MD 20771, USA. NR 32 TC 21 Z9 21 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 MAR PY 1991 VL 101 IS 3 BP 1075 EP 1088 DI 10.1086/115751 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EY997 UT WOS:A1991EY99700031 ER PT J AU FRACASSINI, M FRACASSINI, LEP PASTORI, L TEAYS, TJ MARIANI, A AF FRACASSINI, M FRACASSINI, LEP PASTORI, L TEAYS, TJ MARIANI, A TI CHROMOSPHERIC ACTIVITY IN DELTA-SCUTI STARS - THE SUSPECTED VARIABLE TAU-CYGNI SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE STARS, CHROMOSPHERES OF; STARS, DELTA-SCU; STARS, INDIVIDUAL TAU-CYG; UV RADIATION ID LOCAL INTERSTELLAR-MEDIUM; MG-II; CLASSICAL CEPHEIDS; COOL STARS; EMISSIONS; GIANTS; LINES AB High-resolution IUE spectra of the suspected variable tau-Cyg were obtained to search for a possible variability of the Mg II h, k double-peaked emission. The observations, spanning an interval of about 6.3 h, have shown flux excursions within or just near 15%, value suggested by some Authors as limit to detect actual variations with IUE spectra. A variability, difficult to explain, could be present in the ratios F(k2v/F(k2r. The emission fluxes seem to be hingher than those of the delta Scuti variables Q Pup and beta Cas. This comparison could give some insights on the possible role of the convection on the pulsational and chromospheric activities of tau-Cyg. A positive correlation between the total emission fluxes and the rotational velocities of these stars was found. C1 UNIV MILAN, DIPARTMENTO FIS, VIA CELORIA 16, I-20133 MILAN, ITALY. OSSERV ASTRON MERATE, I-22055 MERATE, ITALY. NASA, GODDARD SPACE FLIGHT CTR, IUE OBSERV, COMP SCI CORP, GREENBELT, MD 20771 USA. NR 32 TC 2 Z9 2 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 MAR PY 1991 VL 243 IS 2 BP 458 EP 462 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE155 UT WOS:A1991FE15500024 ER PT J AU GRIM, RJA BAAS, F GEBALLE, TR GREENBERG, JM SCHUTTE, W AF GRIM, RJA BAAS, F GEBALLE, TR GREENBERG, JM SCHUTTE, W TI DETECTION OF SOLID METHANOL TOWARD W33A SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE INTERSTELLAR MEDIUM, DUST; MOLECULES; LINES, IDENTIFICATIONS; SPECTROSCOPY ID TIME-DEPENDENT CHEMISTRY; DENSE MOLECULAR CLOUDS; ABSORPTION FEATURES; INFRARED-SPECTROSCOPY; MICRON ABSORPTION; GRAIN MANTLES; SPECTRA; PROTOSTARS; CO AB A recently detected absorption feature at 3.53-mu-m in the spectrum of W 33A has been assigned to methanol (CH3OH). Its optical depth implies that methanol is the second most abundant molecule (7% relative to H2O) in the grain mantles in the line of sight towards W 33A observed to date. Laboratory experiments have shown that the implied abundance is difficult to explain by UV irradiation of the dust grains alone. Grain surface reactions or condensation directly out of the gas phase must also play roles, but the relative contributions of the various processes are difficult to estimate. The optical depth of the 3.53-mu-m feature constraints the contribution of methanol to the 6.8-mu-m feature in W33A to be 10% or less, requiring the contribution of at least on other compound to this feature, while the estimated contribution to the 4.9-mu-m absorption band is even smaller. Only a small contribution of formaldehyde (H2CO) is consistent with the observed 3.53-mu-m band profile. In contrast the methanol, formaldehyde can be produced readily by photochemical reactions within the ice mantle. C1 JOINT ASTRON CTR, 665 KOMOHANA ST, HILO, HI 96720 USA. LEIDEN STATE UNIV, HUYGENS LAB, ASTROPHYS LAB, 2312 AV LEIDEN, NETHERLANDS. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 24 TC 99 Z9 99 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 MAR PY 1991 VL 243 IS 2 BP 473 EP 477 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE155 UT WOS:A1991FE15500027 ER PT J AU TELESCO, CM CAMPINS, H JOY, M DIETZ, K DECHER, R AF TELESCO, CM CAMPINS, H JOY, M DIETZ, K DECHER, R TI INFRARED MAPPING OF M82 - A STARBURST IN AN EDGE-ON BARRED GALAXY SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (M82); GALAXIES, INTERSTELLAR MATTER; GALAXIES, PHOTOMETRY; GALAXIES, STRUCTURE ID ENHANCED STAR FORMATION; ABSOLUTE CALIBRATION; MOLECULAR CLOUDS; SPIRAL STRUCTURE; MICRON EMISSION; VELOCITY-FIELD; DENSITY WAVES; GAS-DYNAMICS; SMALL GRAINS; NUCLEUS AB We present new 1-30-mu-m images of the starburst galaxy M82. The appearance of M82 at 2-mu-m indicates that a bar approximately 1 kpc long is located at its center. This bar may dramatically influence the gas dynamics and may have caused the formation of the central gas and dust toroid associated with the luminous episode of star formation. Our mid-IR maps define the structure of the toroid out to 30-mu-m and show that the extent of the emitting region is at least 1.3 kpc. The absorption optical depth determined from 1-2-mu-m colors corresponds to A(v) less-than-or-similar-to 8 and is distributed in a ridge spanning the starburst region and closely resembling the distribution of H I optical depth. Finally, we consider the contribution that very small grains may make to the 10-mu-m emission and conclude by comparison to Galactic H II regions that their mid-IR emission is significant. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. UNIV FLORIDA,DEPT ASTRON,GAINESVILLE,FL 32611. NR 84 TC 105 Z9 105 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 MAR 1 PY 1991 VL 369 IS 1 BP 135 EP 146 DI 10.1086/169744 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX523 UT WOS:A1991EX52300013 ER PT J AU BRAINERD, JJ MESZAROS, P AF BRAINERD, JJ MESZAROS, P TI DYNAMIC EFFECTS ON CYCLOTRON SCATTERING IN PULSAR ACCRETION COLUMNS SO ASTROPHYSICAL JOURNAL LA English DT Article DE PULSARS; RADIATIVE TRANSFER; STARS, ACCRETION; X-RAYS, SOURCES ID SELF-CONSISTENT DESCRIPTION; X-RAY PULSARS; STRONGLY MAGNETIZED PLASMA; NEUTRON STAR ATMOSPHERES; RADIATIVE-TRANSFER; LINE FORMATION; SPECTRA; MODELS; HERCULES-X-1; LUMINOSITY AB The bulk infall motion of an X-ray pulsar accretion column alters the spectrum and the directionality of the primary radiation produced at the base of the polar cap. We examine this effect in the regime where the accretion column is optically thin to Thomson scattering and optically thick to resonant Compton scattering. Photons propagate freely through the column until the photon frequency equals the local cyclotron frequency, at which point the radiation is scattered, much of it back toward the star. The radiation pressure in this regime is insufficient to stop the infall. Some of the scattered radiation heats the stellar surface around the base of the column, which adds a softer component to the spectrum. The partial blocking by the accretion column of X-rays from the surface produces a fan beam emission pattern. X-rays above the surface cyclotron frequency freely escape and are characterized by a pencil beam. Gravitational light bending, which is one of several general relativistic effects present in this problem, produces a pencil beam pattern of column-scattered radiation in the antipodal direction. The interaction of radiation with the accretion column produces a cyclotron feature that is strongly angle-dependent. C1 UNIV CHICAGO,CHICAGO,IL 60637. PENN STATE UNIV,DEPT ASTRON & ASTROPHYS,DAVEY LAB 525,UNIVERSITY PK,PA 16802. RP BRAINERD, JJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES 65,HUNTSVILLE,AL 35812, USA. NR 31 TC 24 Z9 24 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 1991 VL 369 IS 1 BP 179 EP 190 DI 10.1086/169749 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX523 UT WOS:A1991EX52300018 ER PT J AU BUHL, D CHIN, G GOLDSTEIN, JJ AF BUHL, D CHIN, G GOLDSTEIN, JJ TI DISCOVERY OF A DOPPLER-LIMITED CO LINE IN THE UPPER MESOSPHERE OF VENUS - A NEW DYNAMIC PROBE SO ASTROPHYSICAL JOURNAL LA English DT Article ID CARBON-MONOXIDE; THERMOSPHERE; CIRCULATION; ATMOSPHERE AB The presence of CO in the upper atmosphere of Venus is a consequence of the photochemistry of CO2, the dominant atmospheric constituent. In 1989 December we observed the J = 1-2 transition of CO at 230 GHz. In addition to the broad absorption line first reported by Kakar et al. in 1976, we discovered a narrow absorption feature at the center of the line due to upper mesospheric CO, where the temperature profile starts to exhibit diurnal variation with altitude (approximately 100 km). The narrow feature is approximately 600 kHz wide and is predominantly Doppler-broadened. The Doppler core provides a new means of measuring wind velocities at these altitudes in the atmosphere of Venus. Detection of small Doppler shifts in the line core can in principle be used to measure winds with an accuracy of 10 m s-1. Results are presently limited by the 17 kHz uncertainty in the measured rest frequency, corresponding to a systematic error in wind velocity up to 22 m s-1, and the absence of laboratory measurements of the pressure shift in CO by CO2. C1 NATL AIR & SPACE MUSEUM,ASTROPHYS LAB,WASHINGTON,DC 20560. RP BUHL, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,PLANETARY SYST BRANCH,GREENBELT,MD 20771, USA. RI Chin, Gordon/E-1520-2012 NR 33 TC 8 Z9 8 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 MAR 1 PY 1991 VL 369 IS 1 BP L17 EP L20 DI 10.1086/185949 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX527 UT WOS:A1991EX52700005 ER PT J AU PRESTWICH, AH JOY, M AF PRESTWICH, AH JOY, M TI COOLING FLOWS AND THE FORMATION OF MASSIVE HALOS IN CD GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES; CLUSTERING GALAXIES; X-RAYS STARS; LOW MASS ID BRIGHTEST CLUSTER MEMBERS; X-RAY-EMISSION; STAR FORMATION; ELLIPTICAL GALAXIES; MERGERS; EVOLUTION; MATTER AB X-ray brightness profiles of galaxy clusters frequently indicate the presence of a hot gaseous envelope, and theoretical models predict that numerous low-mass stars will be formed as these gaseous halos cool and contract toward the center of the cluster potential. In this Letter, we model the optical surface brightness profiles of the halos seen in six cooling flow galaxies and conclude that the optical profiles and mass-to-light ratios are consistent with the cooling flow accretion hypothesis. RP PRESTWICH, AH (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES 65,HUNTSVILLE,AL 35812, USA. NR 28 TC 6 Z9 6 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 1991 VL 369 IS 1 BP L1 EP L4 DI 10.1086/185945 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX527 UT WOS:A1991EX52700001 ER PT J AU LEISAWITZ, D DEGEUS, EJ AF LEISAWITZ, D DEGEUS, EJ TI A 21 CENTIMETER LINE SURVEY OF A REGION AROUND 4 OUTER GALAXY OPEN CLUSTERS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE CLUSTERS, OPEN; INTERSTELLAR, MATTER AB To investigate the role of atomic gas in the interaction of massive stars with the interstellar medium, a 21 cm survey was made of a region surrounding four young, outer Galaxy open clusters, NGC 281, 433, 436, and 457. A rectangular area ranging in Galactic longitude from 115-degrees to 133-degrees, and in latitude from -10-degrees to -1-degrees, was observed with the NRAO 140 foot telescope. Most of this region was fully sampled, resulting in spatial resolution equal to the telescope's 21' beamwidth. The data are presented as longitude-latitude and latitude-velocity contour maps. A catalog of atomic gas features (e.g., clouds, filaments, and shells) is given. C1 UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742. RP LEISAWITZ, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INFRARED ASTROPHYS BRANCH,ASTRON & SOLAR PHYS LAB,CODE 685,GREENBELT,MD 20771, USA. NR 9 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD MAR PY 1991 VL 75 IS 3 BP 835 EP 868 DI 10.1086/191550 PG 34 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EZ328 UT WOS:A1991EZ32800006 ER PT J AU STENCEL, RE BACKMAN, DE AF STENCEL, RE BACKMAN, DE TI A SURVEY FOR INFRARED EXCESSES AMONG HIGH GALACTIC LATITUDE SAO STARS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE INFRARED, SOURCES; STARS, CIRCUMSTELLAR SHELLS ID SPECKLE INTERFEROMETRIC MEASUREMENTS; CLOSE BINARY-SYSTEMS; IRAS OBSERVATIONS; BETA-PICTORIS; MAIN-SEQUENCE; CIRCUMSTELLAR ENVELOPES; LINE EMISSION; SHELL STARS; B-TYPE; COMPONENTS AB This project involves extending the previous analysis of infrared excesses among a volume-limited sample of 134 nearby A-K main-sequence stars to a magnitude-limited sample of stars, culled from the SAO Catalog, with excesses determined from the IRAS Point Source Catalog flux density ratios. This new sample includes 5706 B-M type stars, 379 of which have infrared excesses. Our objective involved use of a statistically complete survey of objects in a standard catalog in order to assess the frequency with which different physical processes can affect the infrared output of stars. These processes include, but are not limited to, orbiting cold particle clouds (Vega-like, star/planet formation remnants), and the onset of rapid mass loss (evolved stars). We conclude that cold disks are consistent with the infrared excesses found among A-G dwarfs and G-K giants in our sample. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP STENCEL, RE (reprint author), UNIV COLORADO,CTR ASTROPHYS & SPACE ASTRON,CAMPUS BOX 391,BOULDER,CO 80309, USA. NR 64 TC 55 Z9 55 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 MAR PY 1991 VL 75 IS 3 BP 905 EP 924 DI 10.1086/191553 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EZ328 UT WOS:A1991EZ32800009 ER PT J AU WHITE, GL JAUNCEY, DL HARVEY, BR SAVAGE, A GULKIS, S PRESTON, RA PETERSON, BA REYNOLDS, JE NICOLSON, GD MALIN, DF AF WHITE, GL JAUNCEY, DL HARVEY, BR SAVAGE, A GULKIS, S PRESTON, RA PETERSON, BA REYNOLDS, JE NICOLSON, GD MALIN, DF TI ASTROMETRY OF SOUTHERN RADIO-SOURCES SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 100TH COLLOQUIUM OF THE INTERNATIONAL ASTRONOMICAL UNION - GEORGE TELEKI MEMORIAL COLLOQUIUM ON FUNDAMENTALS OF ASTROMETRY CY SEP 08-11, 1987 CL BELGRAD, YUGOSLAVIA SP INT ASTRON UNION ID OPTICAL IDENTIFICATIONS; INTERFEROMETER; POSITIONS AB An overview is presented of a number of astrometry and astrophysics programs based on radio sources from the Parkes 2.7 GHz catalogues. The programs cover the optical identification and spectroscopy of flat-spectrum Parkes sources and the determination of their milliarc-second radio structures and positions. Work is also in progress to tie together the radio and Hipparcos positional reference frames. A parallel program of radio and optical astrometry of southern radio stars is also under way. C1 CSIRO,DIV RADIOPHYS,SYDNEY,NSW,AUSTRALIA. CALTECH,JET PROP LAB,PASADENA,CA 91109. AUSTRALIAN NATL UNIV,MT STROMLO & SIDING SPRING OBSERV,WODEN,ACT 2606,AUSTRALIA. ANGLO AUSTRALIAN OBSERV,EPPING,NSW 2121,AUSTRALIA. NR 22 TC 1 Z9 1 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 MAR PY 1991 VL 177 IS 1-2 BP 79 EP 83 DI 10.1007/BF00643657 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FU440 UT WOS:A1991FU44000015 PM 11538705 ER PT J AU BLACK, D DYER, J NISHIOKA, K SCARGLE, J SOBECK, C LEVY, E MCMILLAN, R CASTELAZ, M GATEWOOD, G STEIN, J BUFFINGTON, A AF BLACK, D DYER, J NISHIOKA, K SCARGLE, J SOBECK, C LEVY, E MCMILLAN, R CASTELAZ, M GATEWOOD, G STEIN, J BUFFINGTON, A TI THE ASTROMETRIC TELESCOPE FACILITY SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 100TH COLLOQUIUM OF THE INTERNATIONAL ASTRONOMICAL UNION - GEORGE TELEKI MEMORIAL COLLOQUIUM ON FUNDAMENTALS OF ASTROMETRY CY SEP 08-11, 1987 CL BELGRAD, YUGOSLAVIA SP INT ASTRON UNION AB The Astrometric Telescope Facility (ATF) proposed for use on NASA's planned Space Station is similar in form and data output to ground-based long focus astrometric instruments. With a focal plane scale of 12.7 arc seconds/mm, the strawman design has a field size of 10 arc min square and a limiting visual magnitude fainter than 16. Output from an observation includes the X and Y coordinates of each star and its relative brightness. The targeted precision for the AFT is 0.00001 arc seconds. Portions of the observing program will be made available to members of the astronomical community. C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. UNIV PITTSBURGH,ALLEGHENY OBSERV,PITTSBURGH,PA 15260. UNIV CALIF SAN DIEGO,LA JOLLA,CA 92093. RP BLACK, D (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 15 TC 1 Z9 1 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 MAR PY 1991 VL 177 IS 1-2 BP 307 EP 313 DI 10.1007/BF00643696 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FU440 UT WOS:A1991FU44000054 ER PT J AU DYER, JW NISHIOKA, K SOBECK, CK GATEWOOD, GD LEVY, EH AF DYER, JW NISHIOKA, K SOBECK, CK GATEWOOD, GD LEVY, EH TI CONCEPTUAL DESIGN CONSIDERATIONS FOR THE ASTROMETRIC TELESCOPE FACILITY SO ASTROPHYSICS AND SPACE SCIENCE LA English DT Article; Proceedings Paper CT 100TH COLLOQUIUM OF THE INTERNATIONAL ASTRONOMICAL UNION - GEORGE TELEKI MEMORIAL COLLOQUIUM ON FUNDAMENTALS OF ASTROMETRY CY SEP 08-11, 1987 CL BELGRAD, YUGOSLAVIA SP INT ASTRON UNION C1 UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. UNIV PITTSBURGH,ALLEGHENY OBSERV,PITTSBURGH,PA 15260. RP DYER, JW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 4 TC 1 Z9 1 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 MAR PY 1991 VL 177 IS 1-2 BP 315 EP 319 DI 10.1007/BF00643697 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FU440 UT WOS:A1991FU44000055 ER PT J AU WU, MLC AF WU, MLC TI GLOBAL PRECIPITATION ESTIMATES FROM SATELLITE - USING DIFFERENCE FIELDS OF OUTGOING LONG-WAVE-RADIATION SO ATMOSPHERE-OCEAN LA English DT Article ID RAINFALL; TELECONNECTIONS; CLOUD AB Global precipitation estimates using satellite data are derived using difference fields of outgoing long-wave radiation (OLR). The difference field consist of clear OLR minus cloudy OLR, which is a measure of long-wave cloud radiative forcing at the top of the earth-atmosphere system; and clear daytime OLR minus clear night-time OLR, which is a measure of the diurnal variation of surface heating. All geophysical parameters used to compute OLR are derived from an analysis of the HIRS2/MSU sounding data. The derived global precipitation estimates show good agreement with collocated raingauge data over land. The correlation coefficient between the precipitation estimates derived using difference fields of OLR and raingauge data over land is about 0.65 for the FGGE year. The correlation coefficient between precipitation estimates derived using different fields of OLR and the GOES Precipitation Index (GPI) fraction is about 0.914 from 30-degrees-S to 30-degrees-N for July 1983, and between the precipitation estimates derived using difference fields of OLR and the difference field of atmospheric reflectance is about 0.86. Using one set of coefficients, global precipitation fields are derived for each 10-day period and each month of the FGGE year (from December 1978 to November 1979). These fields contain rich information on seasonal variations. RP WU, MLC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 911,GREENBELT,MD 20771, USA. NR 22 TC 8 Z9 8 U1 0 U2 1 PU CANADIAN METEOROLOGICAL OCEANOGRAPHIC SOC PI OTTAWA PA 150 LOUIS PASTEUR PVT., STE 112, MCDONALD BUILDING, OTTAWA ON K1N 6N5, CANADA SN 0705-5900 J9 ATMOS OCEAN JI Atmos.-Ocean PD MAR PY 1991 VL 29 IS 1 BP 150 EP 174 PG 25 WC Meteorology & Atmospheric Sciences; Oceanography SC Meteorology & Atmospheric Sciences; Oceanography GA FF056 UT WOS:A1991FF05600010 ER PT J AU BILLINGS, CE DEMOSTHENES, T WHITE, TR OHARA, DB AF BILLINGS, CE DEMOSTHENES, T WHITE, TR OHARA, DB TI EFFECTS OF ALCOHOL ON PILOT PERFORMANCE IN SIMULATED FLIGHT SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB Ethyl alcohol's known ability to produce reliable decrements in pilot performance was used in a study designed to evaluate objective methods for assessing pilot performance. Four air carrier pilot volunteers were studied during eight simulated flights between San Francisco and Los Angeles in a Boeing 727-232 simulator. Two flights were conducted at each of four target blood alcohol levels, 0, 0.025, 0.050, and 0.075%. Each flight lasted about 1 h. Flights were conducted with full crews in a full simulated ATC environment. Data from direct observations and videotapes were used to examine discrete errors committed by the subjects. Total errors increased linearly and significantly with increasing blood alcohol. Planning and performance errors, procedural errors and failures of vigilance each increased significantly in one or more pilots and in the group as a whole. Failures of crew coordination were not associated with blood alcohol level. Serious errors increased significantly even at the lowest alcohol level studied, 0.025% (25 mg/dl), compared with control values. C1 NASA,AMES RES CTR,HUMAN RES FACIL,MOFFETT FIELD,CA 94035. RP BILLINGS, CE (reprint author), NASA,AMES RES CTR,DIV AEROSP HUMAN FACTORS RES,262-4,MOFFETT FIELD,CA 94035, USA. NR 3 TC 26 Z9 26 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 MAR PY 1991 VL 62 IS 3 BP 233 EP 235 PG 3 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA EZ171 UT WOS:A1991EZ17100007 PM 2012569 ER PT J AU ARATOW, M HARGENS, AR MEYER, JU ARNAUD, SB AF ARATOW, M HARGENS, AR MEYER, JU ARNAUD, SB TI POSTURAL RESPONSES OF HEAD AND FOOT CUTANEOUS MICROVASCULAR FLOW AND THEIR SENSITIVITY TO BED REST SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article ID EARLY CARDIOVASCULAR ADAPTATION; BLOOD-FLOW; ZERO GRAVITY; LOCAL REFLEX; HUMAN-SKIN; PRESSURE; FOREARM; MICROCIRCULATION; RESISTANCE; MECHANISMS AB To explore the mechanism for facial puffiness, headache, and nasal congestion associated with microgravity and cephalad fluid shifts, the postural responses of the cutaneous microcirculation in the forehead and dorsum of the foot of eight healthy men were studied by changing body position on a tilt table and measuring blood flows with a laser-Doppler flowmeter. Increasing arterial pressure in the feet by moving from a -6-degrees head-down tilt to a 60-degrees head-up posture decreased foot cutaneous flow by 46.5 +/- 12.0% (mean +/- S.E.; p < 0.05). Raising arterial pressure in the head by tilting from the 60-degrees head-up to -6-degrees head-down posture increased forehead cutaneous flow by 25.5 +/- 7.2% (p < 0.05). To investigate the possibility that these opposite responses could be modified by simulated microgravity, tilt tests were repeated after 7 d of -6-degrees head-down tilt bed rest. On the 1st and 2nd days after bed rest, flows in the foot were decreased by 69.4 +/- 8.8% and 45.8 +/- 18.7%, respectively, and increased in the head by 39.3 +/- 8.6% and 15.5 +/- 5.9%, respectively. These responses were not significantly different from those recorded before bed rest. Therefore, cutaneous microcirculatory flow in the feet is well regulated to prevent edema when shifting to an upright position, whereas there is less regulation in the head microcirculation. The lack of regulation in the forehead cutaneous microcirculation increases capillary flow, and consequently increases fluid filtration. This phenomenon helps explain the facial edema associated with the simulated or actual microgravity environment. C1 NASA,AMES RES CTR,DIV LIFE SCI 23911,MOFFETT FIELD,CA 94035. NR 32 TC 33 Z9 35 U1 0 U2 2 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 MAR PY 1991 VL 62 IS 3 BP 246 EP 251 PG 6 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA EZ171 UT WOS:A1991EZ17100010 PM 2012572 ER PT J AU ROSI, M BAUSCHLICHER, CW LANGHOFF, SR AF ROSI, M BAUSCHLICHER, CW LANGHOFF, SR TI THEORETICAL-STUDY OF THE SPECTROSCOPY OF AL-2+ SO CHEMICAL PHYSICS LA English DT Article ID ALUMINUM CLUSTERS; AL2; CONSTANTS; ENERGIES AB The electronic states of Al2+ below about 40 000 cm-1 are studied using a CASSCF/MRCI approach in a large Gaussian basis set. The computed spectroscopic constants, excitation energies, Einstein coefficients, and radiative lifetimes should give insight into the spectroscopy of this ion. RP ROSI, M (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. RI Rosi, Marzio/L-5748-2015 OI Rosi, Marzio/0000-0002-1264-3877 NR 12 TC 2 Z9 2 U1 1 U2 7 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0301-0104 J9 CHEM PHYS JI Chem. Phys. PD MAR 1 PY 1991 VL 151 IS 1 BP 1 EP 9 DI 10.1016/0301-0104(91)80001-X PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FA715 UT WOS:A1991FA71500001 ER PT J AU IMHOF, WL VOSS, HD MOBILIA, J DATLOWE, DW MCGLENNON, JP BAKER, DN AF IMHOF, WL VOSS, HD MOBILIA, J DATLOWE, DW MCGLENNON, JP BAKER, DN TI RELATIVISTIC ELECTRON ENHANCEMENTS - SIMULTANEOUS MEASUREMENTS FROM SYNCHRONOUS AND LOW ALTITUDE SATELLITES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB We present here for the first time simultaneous measurements of trapped relativistic electron enhancements at synchronous altitude and precipitating electrons in the bounce loss cone at low altitudes. The measurements show that the daily variations in the precipitation flux for L > 5 correlated well with the daily variations in the total flux at high altitude, both with respect to sudden enhancements as well as flux depletions. The daily averaged precipitating flux (E > 1 MeV) at L = 6.1 to 7.1 was about 0.3 percent of the daily averaged directional flux (E greater-than-or-equal-to 1.5 MeV) observed at synchronous altitude, whereas within narrow spikes the precipitating directional fluxes were often within a factor of 10 of the daily averaged trapped fluxes. Strong depletions in the synchronous altitude greater-than-or-equal-to 1.5 MeV electron intensities are shown to be associated with low altitude measurements of the equatorward movement of precipitating spikes to lower L shells. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP IMHOF, WL (reprint author), LOCKHEED PALO ALTO RES LABS,DEPT 91-20,BLDG 255,3251 HANOVER ST,PALO ALTO,CA 94304, USA. NR 7 TC 18 Z9 18 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAR PY 1991 VL 18 IS 3 BP 397 EP 400 DI 10.1029/91GL00132 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FC748 UT WOS:A1991FC74800011 ER PT J AU AIKIN, AC CHANIN, ML NASH, J KENDIG, DJ AF AIKIN, AC CHANIN, ML NASH, J KENDIG, DJ TI TEMPERATURE TRENDS IN THE LOWER MESOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MIDDLE ATMOSPHERE AB The largest atmospheric temperature changes due to the increase of greenhouse gases are expected in the 40 to 60 km altitude region, where enhanced infrared cooling decreases the temperature. Ten-year (1980-1990) temperature trends at 55 km and 0.4 mb, derived using data from the ground-based lidar at Haute Provence, 44-degrees-N 6-degrees-E, and the SSU channel 47X on several satellites, are presented. These data show temperature decreases that are as large and in some cases exceed predictions based on current models. At 44-degrees-N, the ground-based lidar and satellite techniques give a negative trend of -0.10 +/- 0.04% per year and -0.14 +/- 0.02% per year, respectively. Agreement between these two data sets based on different measurement techniques gives confidence in the detected trends at this latitude. Further analysis of the SSU 47X satellite data between 45-degrees-S and 45-degrees-N indicates a maximum decline of 0.16% per year near 30-degrees-N. A minimum trend decrease of 0.07% per year is detected between 20-degrees and 30-degrees-S. Based on NOAA satellite radiance observations, these long-term temperature changes are larger than changes at any of the other stratospheric levels below 55 km monitored during this period. C1 SERV AERON,VERRIERES BUISSON,FRANCE. UK METEOROL OFF,BRACKNELL,ENGLAND. ST SYST CORP,LANHAM,MD 20706. RP AIKIN, AC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 916,GREENBELT,MD 20771, USA. NR 16 TC 42 Z9 43 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 MAR PY 1991 VL 18 IS 3 BP 416 EP 419 DI 10.1029/91GL00233 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FC748 UT WOS:A1991FC74800016 ER PT J AU KENT, GS MCCORMICK, MP AF KENT, GS MCCORMICK, MP TI SEPARATION OF CLOUD AND AEROSOL IN 2-WAVELENGTH SATELLITE OCCULTATION DATA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC AEROSOL; SAGE DATA; DISTRIBUTIONS; EXTINCTION AB The separation of cloud and aerosol extinction in satellite solar occultation data is discussed in the context of a simple model for the wavelength dependence of extinction. The model is shown graphically in terms of a scatter plot of 0.525-mu-m extinction versus 1.02-mu-m extinction. This plot contains two regions: one arising from aerosol and the other from an aerosol/cloud mixture. Examples of two-wavelength data obtained by the SAGE II instrument are presented and found to agree well with the model. The single wavelength criteria used previously to separate cloud and aerosol are examined in the context of the two-wavelength model. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. RP KENT, GS (reprint author), SCI & TECHNOL CORP,101 RES DR,HAMPTON,VA 23666, USA. NR 12 TC 15 Z9 15 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAR PY 1991 VL 18 IS 3 BP 428 EP 431 DI 10.1029/90GL02783 PG 4 WC Geosciences, Multidisciplinary SC Geology GA FC748 UT WOS:A1991FC74800019 ER PT J AU GORNITZ, V AF GORNITZ, V TI GLOBAL COASTAL HAZARDS FROM FUTURE SEA-LEVEL RISE SO GLOBAL AND PLANETARY CHANGE LA English DT Article ID EROSION; CLIMATE; DELTA AB A rise of sea level between 0.3 and 0.9 m by the end of the next century, caused by predicted greenhouse climate warming, would endanger human populations, cities, ports, and wetlands in low-lying coastal areas, through inundation, erosion and salinization. The consequences of a global sea level rise would be spatially non-uniform because of local or regional vertical crustal movements, differential resistance to erosion, varying wave climates, and changeable longshore currents. Although many factors can influence sea level, leading to a noisy record, various studies utilizing tide-gauge data find an average global rate of sea level rise of 1-2 mm/yr, over the last 100 years. This trend is part of a general rise over the last 300 years, since the low point of the Little Ice Age. Sea level rise may accelerate 3-8 times over present rates, within the next century. The permanently inundated coastal zone would extend to a depth equivalent to the vertical rise in sea level. Major river deltas, coastal wetlands and coral islands would be most affected. Episodic flooding by storm waves and surges would penetrate even farther inland. Beach and cliff erosion will be accentuated. Saltwater penetration into coastal aquifers and estuaries could contaminate urban water supplies and affect agricultural production. Research on relative risks and impacts of sea level rise on specific localities is still at an early stage. Development of a global coastal hazards data base, intended to provide an overview of the relative vulnerabilities of the world's coastlines, is described in this paper. To date, information on seven variables, associated with inundation and erosion hazards, has been compiled for the U.S., and parts of Canada and Mexico. A coastal vulnerability index (CVI) has been designed to flag high risk coastal segments. Preliminary results are presented for the eastern United States, as a test case. C1 COLUMBIA UNIV,NEW YORK,NY 10025. RP GORNITZ, V (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,GREENBELT,MD 20771, USA. NR 70 TC 80 Z9 96 U1 10 U2 55 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0921-8181 J9 GLOBAL PLANET CHANGE JI Glob. Planet. Change PD MAR PY 1991 VL 89 IS 4 BP 379 EP 398 DI 10.1016/0921-8181(91)90118-G PG 20 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA FE976 UT WOS:A1991FE97600005 ER PT J AU BURATTI, BJ MOSHER, JA AF BURATTI, BJ MOSHER, JA TI COMPARATIVE GLOBAL ALBEDO AND COLOR MAPS OF THE URANIAN SATELLITES SO ICARUS LA English DT Article ID DISK-INTEGRATED PHOTOMETRY; VOYAGER-2; URANUS; ICE; MIRANDA; SURFACE; SYSTEM RP BURATTI, BJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 42 TC 26 Z9 26 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 MAR PY 1991 VL 90 IS 1 BP 1 EP 13 DI 10.1016/0019-1035(91)90064-Z PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FD717 UT WOS:A1991FD71700001 ER PT J AU COURTIN, R WAGENER, R MCKAY, CP CALDWELL, J FRICKE, KH RAULIN, F BRUSTON, P AF COURTIN, R WAGENER, R MCKAY, CP CALDWELL, J FRICKE, KH RAULIN, F BRUSTON, P TI UV SPECTROSCOPY OF TITANS ATMOSPHERE, PLANETARY ORGANIC-CHEMISTRY AND PREBIOLOGICAL SYNTHESIS .2. INTERPRETATION OF NEW IUE OBSERVATIONS IN THE 220-335 NM RANGE SO ICARUS LA English DT Article ID INFRARED OBSERVATIONS; INHOMOGENEOUS MODELS; AEROSOL DISTRIBUTION; PHOTOCHEMISTRY; NEPTUNE; URANUS; SCATTERING; PHOTOMETRY; VOYAGER-1; SPECTRA C1 SUNY STONY BROOK,DEPT EARTH & SPACE SCI,ASTRON PROGRAM,STONY BROOK,NY 11794. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. YORK UNIV,DEPT PHYS,N YORK M3J 1P3,ONTARIO,CANADA. UNIV BONN,INST PHYS,W-5300 BONN,GERMANY. UNIV PARIS 12,PHYS CHIM ENVIRONM LAB,F-94010 CRETEIL,FRANCE. INST ASTROPHYS SPATIALE,F-91371 VERRIERES BUISSON,FRANCE. INST SPACE & TERR SCI,SPACE ASTROPHYS LAB,CONCORD L4K 3C8,ONTARIO,CANADA. RP COURTIN, R (reprint author), OBSERV PARIS,CNRS,UA 264,RECH SPATIAL & LAB,F-92195 MEUDON,FRANCE. RI Wagener, Richard/B-5445-2008 OI Wagener, Richard/0000-0003-3892-1182 NR 47 TC 51 Z9 51 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAR PY 1991 VL 90 IS 1 BP 43 EP 56 DI 10.1016/0019-1035(91)90067-4 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FD717 UT WOS:A1991FD71700004 PM 11538098 ER PT J AU GREELEY, R MARSHALL, JR CLEMENS, D DOBROVOLSKIS, AR POLLACK, JB AF GREELEY, R MARSHALL, JR CLEMENS, D DOBROVOLSKIS, AR POLLACK, JB TI VENUS - CONCENTRATIONS OF RADAR-REFLECTIVE MINERALS BY WIND SO ICARUS LA English DT Article ID SURFACE; SIMULATIONS; ROCKS C1 NASA,AMES RES CTR,PLANETARY GEOL PROGRAM,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP GREELEY, R (reprint author), ARIZONA STATE UNIV,DEPT GEOL,TEMPE,AZ 85287, USA. NR 28 TC 10 Z9 10 U1 1 U2 1 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAR PY 1991 VL 90 IS 1 BP 123 EP 128 DI 10.1016/0019-1035(91)90074-4 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FD717 UT WOS:A1991FD71700011 ER PT J AU ARAKI, S AF ARAKI, S TI THE DYNAMICS OF PARTICLE DISKS .3. DENSE AND SPINNING PARTICLE DISKS SO ICARUS LA English DT Article ID STRESS TENSOR; GRANULAR FLOW; SHEAR FLOWS; RINGS; SIMULATIONS RP ARAKI, S (reprint author), CALTECH,JET PROP LAB,MS 183-501,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 39 Z9 39 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAR PY 1991 VL 90 IS 1 BP 139 EP 171 DI 10.1016/0019-1035(91)90076-6 PG 33 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FD717 UT WOS:A1991FD71700013 ER PT J AU LANG, RJ LARSSON, AG CODY, JG AF LANG, RJ LARSSON, AG CODY, JG TI LATERAL-MODES OF BROAD AREA SEMICONDUCTOR-LASERS - THEORY AND EXPERIMENT SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article ID QUANTUM-WELL LASERS; MOLECULAR-BEAM EPITAXY; DIODE-LASERS; EFFICIENCY AB We calculate the lateral modes of an ideal broad area laser, including the nonlinear interaction between the carriers and the optical field. The results include periodically modulated near fields and single- and double-lobed far fields similar to those previously measured. The unsaturable losses are higher and quantum efficiencies are lower than those determined from plane-wave approximations. Broad area InGaAs-GaAlAs-GaAs quantum-well lasers are fabricated and measured and found to closely agree with the theory in near, far, and spectrally resolved near fields. An occultation experiment on the far field confirms previously-predicted unstable resonator-like modes with V-shaped phase fronts. RP LANG, RJ (reprint author), CTR SPACE MICROELECTR TECHNOL,JET PROP LAB 302-306,PASADENA,CA 91109, USA. RI Larsson, Anders/P-7275-2015 OI Larsson, Anders/0000-0002-0912-7695 NR 17 TC 61 Z9 61 U1 3 U2 11 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 MAR PY 1991 VL 27 IS 3 BP 312 EP 320 DI 10.1109/3.81329 PG 9 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA FR347 UT WOS:A1991FR34700001 ER PT J AU HEWAGAMA, T OPPENHEIM, UP MUMMA, MJ AF HEWAGAMA, T OPPENHEIM, UP MUMMA, MJ TI ANOMALOUS GAIN IN AN ISOTOPICALLY MIXED CO2-LASER AND APPLICATION TO ABSOLUTE WAVELENGTH CALIBRATION SO IEEE JOURNAL OF QUANTUM ELECTRONICS LA English DT Article ID TRANSITIONS AB Measurements are reported on a grating-tuned CO2 laser, containing an isotopic mixture of (OCO)-O-16-C-12-O-16, (OCO)-O-16-C-12-O-18, and (OCO)-O-18-C-12-O-18. The P6 and R14 lines of (OCO)-O-16-C-12-O-16 were found to have anomalously high intensities. These anomalies are produced by the near coincidence of the transition frequencies in two distinct isotopes, permitting them to act as a single indistinguishable population. These two lines can be used to identify the rotational quantum numbers in the P and R branch spectra, thereby permitting absolute wavelength calibration to be achieved. C1 TECHNION ISRAEL INST TECHNOL,DEPT PHYS,HAIFA,ISRAEL. NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,PLANETARY SYST BRANCH,GREENBELT,MD 20771. RP HEWAGAMA, T (reprint author), UNIV MARYLAND,ASTRON PROGRAM,COLLEGE PK,MD 20742, USA. RI Hewagama, T/C-8488-2012; mumma, michael/I-2764-2013 NR 10 TC 3 Z9 3 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9197 J9 IEEE J QUANTUM ELECT JI IEEE J. Quantum Electron. PD MAR PY 1991 VL 27 IS 3 BP 465 EP 470 DI 10.1109/3.81348 PG 6 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA FR347 UT WOS:A1991FR34700020 ER PT J AU VOAS, J MORELL, L MILLER, K AF VOAS, J MORELL, L MILLER, K TI PREDICTING WHERE FAULTS CAN HIDE FROM TESTING SO IEEE SOFTWARE LA English DT Article C1 COLL WILLIAM & MARY, COMP SCI, WILLIAMSBURG, VA 23185 USA. RP NASA, LANGLEY RES CTR, MS 478, HAMPTON, VA 23665 USA. NR 2 TC 35 Z9 37 U1 1 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1314 USA SN 0740-7459 EI 1937-4194 J9 IEEE SOFTWARE JI IEEE Softw. PD MAR PY 1991 VL 8 IS 2 BP 41 EP 48 DI 10.1109/52.73748 PG 8 WC Computer Science, Software Engineering SC Computer Science GA EZ741 UT WOS:A1991EZ74100008 ER PT J AU NICOL, DM OHALLARON, DR AF NICOL, DM OHALLARON, DR TI IMPROVED ALGORITHMS FOR MAPPING PIPELINED AND PARALLEL COMPUTATIONS SO IEEE TRANSACTIONS ON COMPUTERS LA English DT Article DE MAPPING PROBLEM; PARALLEL ALGORITHMS; PARALLEL PROCESSING; PERFORMANCE OPTIMIZATION; PIPELINED COMPUTATIONS ID PROCESSOR SYSTEM; PERFORMANCE AB This paper extends recent work on the problem of mapping pipelined or parallel computations onto linear array, shared memory, and host-satellite systems. We show how these problems can be solved even more efficiently when computation module execution times are bounded from below, intermodule communication times are bounded from above, and the processors satisfy certain homogeneity constraints. Our improvements have significantly lower time and space complexities than those of the more general algorithms: in one case, we replace an O(nm3) time algorithm for mapping m modules onto n processors with an O(nm log m) time algorithm, and reduce the space requirements from O(nm2) to O(m). We then reduce run-time complexity further with parallel mapping algorithms based on these improvements, that run on the architectures for which they create mappings. C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23665. CARNEGIE MELLON UNIV,SCH COMP SCI,PITTSBURGH,PA 15213. RP NICOL, DM (reprint author), COLL WILLIAM & MARY,DEPT COMP SCI,WILLIAMSBURG,VA 23185, USA. NR 18 TC 31 Z9 31 U1 0 U2 1 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0018-9340 J9 IEEE T COMPUT JI IEEE Trans. Comput. PD MAR PY 1991 VL 40 IS 3 BP 295 EP 306 DI 10.1109/12.76406 PG 12 WC Computer Science, Hardware & Architecture; Engineering, Electrical & Electronic SC Computer Science; Engineering GA FJ186 UT WOS:A1991FJ18600006 ER PT J AU SINGH, C PATTON, AD KUMAR, M WAGNER, HA AF SINGH, C PATTON, AD KUMAR, M WAGNER, HA TI A SIMULATION-MODEL FOR RELIABILITY EVALUATION OF SPACE STATION POWER-SYSTEMS SO IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS LA English DT Article AB A detailed simulation model for reliability evaluation of space station electrical power systems is presented. Dependence of reliability and storage characteristics during the sun and eclipse periods is considered. The charging and discharging of energy storage modules is included on a continuous basis. Sample system studies are also presented. C1 NASA,HOUSTON,TX 77056. RP SINGH, C (reprint author), TEXAS A&M UNIV SYST,DEPT ELECT ENGN,COLLEGE STN,TX 77843, USA. NR 2 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 0093-9994 J9 IEEE T IND APPL JI IEEE Trans. Ind. Appl. PD MAR-APR PY 1991 VL 27 IS 2 BP 331 EP 334 DI 10.1109/28.73621 PG 4 WC Engineering, Multidisciplinary; Engineering, Electrical & Electronic SC Engineering GA FD038 UT WOS:A1991FD03800019 ER PT J AU HUNT, BD FOOTE, MC BAJUK, L AF HUNT, BD FOOTE, MC BAJUK, L TI EDGE-GEOMETRY YBA2CU3O7-X/AU/NB SNS DEVICES SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 APPLIED SUPERCONDUCTIVITY CONF CY SEP 24-28, 1990 CL SNOWMASS, CO SP TELEDYNE WAH CHANG ALBANY, US DOE, HYPRES, GEN DYNAM ID TUNNEL-JUNCTIONS AB The fabrication and electrical properties of edge-geometry YBaCuO/Au/Nb weak links are described. Superconductor/normal-metal/superconductor (SNS) devices of this type serve as sensitive probes of the electrical quality of the YBaCuO/Au interface. For device applications, the edge geometry has the advantage of placing the critical N/S device interface on the longer coherence length a-b surface, and it simplifies the fabrication of weak links with submicron dimensions. These structures are fabricated using laser-ablated, in-situ, c-axis-oriented YBaCuO thin films, with both oxygen-annealed and unannealed YBaCuO/Au interfaces. The YBaCuO film edges are patterned using ion milling, followed by a low energy ion cleaning step and in-situ deposition of Au and Nb. Devices with areas in the 10(-7) to 10(-8) cm2 range have been fabricated with R(n)A products lower than 10(-8) OMEGA-cm2 and critical current densities up to 3 kA/cm2. Josephson-coupling is verified by the observation of microwave steps under 10 GHz microwave irradiation. The best results have been obtained with annealed YBaCuO/Au interfaces. RP HUNT, BD (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 15 TC 6 Z9 6 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 848 EP 851 DI 10.1109/20.133307 PN 2 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY652 UT WOS:A1991EY65200009 ER PT J AU ISRAELSSON, UE STRAYER, DM AF ISRAELSSON, UE STRAYER, DM TI SHIELDING AND FLUX TRAPPING PROPERTIES OF HIGH-TEMPERATURE SUPERCONDUCTORS IN THE SHAPE OF HOLLOW CYLINDERS SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 APPLIED SUPERCONDUCTIVITY CONF CY SEP 24-28, 1990 CL SNOWMASS, CO SP TELEDYNE WAH CHANG ALBANY, US DOE, HYPRES, GEN DYNAM AB Allowing for a field dependent critical current density, we calculate the magnetic field that can be supported by hollow cylinders of varying wall thickness. An adiabatically stable field of 1.0 tesla can be shielded by or trapped in a cylinder with a wall thickness of 0.4 cm if the critical current density varies linearly with magnetic field and has a value of 10(4) A/cm2 at a field of 1.0 tesla. Such a current density appears to be within reach of present state of the art melt processed YBa2Cu3O7 (123) materials. RP ISRAELSSON, UE (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 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 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 1047 EP 1048 DI 10.1109/20.133358 PN 2 PG 2 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY652 UT WOS:A1991EY65200058 ER PT J AU VITTA, S STAN, MA ALTEROVITZ, SA AF VITTA, S STAN, MA ALTEROVITZ, SA TI TEMPERATURE-DEPENDENCE OF THE ANISOTROPY IN MAGNETIC-RELAXATION IN YBA2CU3O7-X THIN-FILMS SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 APPLIED SUPERCONDUCTIVITY CONF CY SEP 24-28, 1990 CL SNOWMASS, CO SP TELEDYNE WAH CHANG ALBANY, US DOE, HYPRES, GEN DYNAM AB The relaxation of diamagnetic magnetization in the c-axis aligned YBa2Cu3O7-x thin film is studied as a function of orientation and temperature in the range 5-50 K at H = 0.2 T. The magnetization M(T,H) in both the orientations H parallel-to c and H perpendicular-to c and at all the temperatures is found to decrease logarithmically with time t. An activation energy for the movement of flux lines U can be obtained using the relation U = -kT {1/M0. dM/dlnt}-1 and is found to be 30-110 meV in the range 5-50 K. For H parallel-to c, U increases continuously with T, where as for H perpendicular-to c, U has two apparent maxima: at T = 10 K and T > 50 K. These results are discussed in terms of the thermally activated flux motion model. RP VITTA, S (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Vitta, Satish/K-7336-2015 OI Vitta, Satish/0000-0003-4138-0022 NR 7 TC 1 Z9 1 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 1083 EP 1085 DI 10.1109/20.133367 PN 2 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY652 UT WOS:A1991EY65200068 ER PT J AU ISRAELSSON, UE STRAYER, DM AF ISRAELSSON, UE STRAYER, DM TI FLUX COMPRESSION MEASUREMENTS IN SINTERED BULK BA2YCU3O7 SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 APPLIED SUPERCONDUCTIVITY CONF CY SEP 24-28, 1990 CL SNOWMASS, CO SP TELEDYNE WAH CHANG ALBANY, US DOE, HYPRES, GEN DYNAM AB Trapping of magnetic fields and subsequent flux compression have been carried out in sintered bulk Ba2YCu3O7 superconductors at 77 K. The field is trapped in two interconnected holes of 0.95 cm and 0.52 cm diameters respectively. By inserting a superconducting plunger with a diameter of 0.93 cm into the larger hole the trapped flux is compressed into the smaller hole where the flux density is measured with a Hall probe. The ratio of the areas available for the magnetic flux before and after compression is 3.7. Deviations from this compression ratio are observed to increase as the trapped field is increased, demonstrating penetration of magnetic flux into the interior of the superconductor. Using a simple extension of the critical state model we demonstrate how the flux compression technique can be used to test the validity of the model and also to calculate the critical current density of the superconductor directly from the measurements. RP ISRAELSSON, UE (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 8 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 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 1170 EP 1173 DI 10.1109/20.133391 PN 2 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY652 UT WOS:A1991EY65200090 ER PT J AU BHASIN, KB WARNER, JD MIRANDA, FA GORDON, WL NEWMAN, HS AF BHASIN, KB WARNER, JD MIRANDA, FA GORDON, WL NEWMAN, HS TI DETERMINATION OF SURFACE-RESISTANCE AND MAGNETIC PENETRATION DEPTH OF SUPERCONDUCTING YBA2CU3O7-DELTA THIN-FILMS BY MICROWAVE-POWER TRANSMISSION MEASUREMENTS SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 APPLIED SUPERCONDUCTIVITY CONF CY SEP 24-28, 1990 CL SNOWMASS, CO SP TELEDYNE WAH CHANG ALBANY, US DOE, HYPRES, GEN DYNAM ID ORIENTED YBA2CU3O7-DELTA AB A novel waveguide power transmission measurement technique has been developed to extract the complex conductivity (sigma* = sigma-1 - j-sigma-2) of superconducting thin films at microwave frequencies. We obtained the microwave conductivity of two laser-ablated YBa2Cu3O7-delta thin films on LaAlO3 with transition temperatures (T(c)) of approximately 86.3 and 82 K, respectively, in the temperature range 25 to 300 K. From the conductivity values we calculated the penetration depth (lambda) to be approximately 0.54 and 0.43-mu-m, and the surface resistance(R(s)) to be approximately 24 and 36 m-OMEGA at 36 GHz and 76 K for the two films under consideration. We further compared the R(s) values with those obtained from the change in the Q-factor of a 36 GHz TE011-mode (OFHC) copper cavity by replacing one of its end walls with the superconducting sample. We found that this technique allows noninvasive characterization of high-T(c) superconducting thin films at microwave frequencies. C1 CASE WESTERN RESERVE UNIV,DEPT PHYS,CLEVELAND,OH 44106. USN,RES LAB,WASHINGTON,DC 20375. RP BHASIN, KB (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 12 TC 13 Z9 13 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 1284 EP 1287 DI 10.1109/20.133418 PN 2 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY652 UT WOS:A1991EY65200116 ER PT J AU FOOTE, MC HUNT, BD BAJUK, LJ AF FOOTE, MC HUNT, BD BAJUK, LJ TI YBA2CU3O7-DELTA/AU/NB SANDWICH GEOMETRY SNS WEAK LINKS ON C-AXIS ORIENTED YBA2CU3O7-DELTA SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 APPLIED SUPERCONDUCTIVITY CONF CY SEP 24-28, 1990 CL SNOWMASS, CO SP TELEDYNE WAH CHANG ALBANY, US DOE, HYPRES, GEN DYNAM ID THIN-FILMS AB Sandwich geometry superconductor/normal metal/superconductor structures have been fabricated on LaAlO3 and cubic zirconia with laser ablated, c-axis oriented YBa2Cu3O7-delta base electrodes, 100-600 angstrom of Au, and Nb counter electrodes, all formed in-situ without breaking vacuum. Junctions range in size from 5 to 20 mu-m on a side. Four probe I-V measurements at 4.2 K show R(n)A products as low as 6x10(-9) OMEGA-cm2 and critical current densities up to 5.2 kA/cm2. AC Josephson steps were observed with the application of 10 GHz radiation. The best results were obtained when the devices were annealed at approximately450 degrees-C in O2 for 30 minutes after Au deposition. RP FOOTE, MC (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 15 TC 5 Z9 5 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 1335 EP 1337 DI 10.1109/20.133973 PN 2 PG 3 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY652 UT WOS:A1991EY65200130 ER PT J AU MCGRATH, WR STERN, JA JAVADI, HHS CYPHER, SR HUNT, BD LEDUC, HG AF MCGRATH, WR STERN, JA JAVADI, HHS CYPHER, SR HUNT, BD LEDUC, HG TI PERFORMANCE OF NBN SUPERCONDUCTIVE TUNNEL-JUNCTIONS AS SIS MIXERS AT 205 GHZ SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 CONF ON APPLIED SUPERCONDUCTIVITY CY SEP 24-28, 1990 CL SNOWMASS, CO AB We have fabricated small area (less-than-or-equal-to 1-mu-2), high current density NbN/MgO/NbN tunnel junctions with I-V characteristics suitable for high frequency mixers. Mesa-geometry junctions with an area of about 1-mu-2 and critical current density of 5-10kA/cm2 are integrated with superconducting microstrip lines designed to resonate out the junction capacitance. Accurate values of junction capacitance and magnetic penetration depth are required for the proper design of the microstrip. We have studied the mixer gain and noise performance near 205 GHz as a function of the inductance provided by the microstrip line. This has confirmed, at a high millimeter wave frequency, values of junction capacitance of 85 fF/mu-2 and recently measured values of magnetic penetration depth of 380 nm. Mixer noise as low as 134 K at 1.5 K has been obtained for properly-tuned junctions. We observe a significant improvement in mixer performance on cooling from 4.2 K to 1.5 K. Edge-geometry junctions with an area of 0.3-mu-2 and critical current density of 18-25 kA/cm2 have also been fabricated. These junctions give a mixer noise of 145 K at 4.2 K without the use of integrated tuning elements. These are the best results ever achieved for NbN-based SIS mixers. RP MCGRATH, WR (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 22 Z9 22 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 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 2650 EP 2653 DI 10.1109/20.133756 PN 4 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY654 UT WOS:A1991EY65400026 ER PT J AU CHOREY, CM BHASIN, KB WARNER, JD JOSEFOWICZ, JY RENSCH, DB NIEH, CW AF CHOREY, CM BHASIN, KB WARNER, JD JOSEFOWICZ, JY RENSCH, DB NIEH, CW TI AN EXPERIMENTAL-STUDY OF HIGH-TC SUPERCONDUCTING MICROSTRIP TRANSMISSION-LINES AT 35 GHZ AND THE EFFECT OF FILM MORPHOLOGY SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 CONF ON APPLIED SUPERCONDUCTIVITY CY SEP 24-28, 1990 CL SNOWMASS, CO ID THIN-FILMS; YBA2CU3O7-X AB Microstrip transmission lines in the form of ring resonators have been fabricated from a number of in-situ grown laser ablated films and post-annealed co-sputtered YBa2Cu3O7-x (YBCO) films. The properties of these resonators have been measured at 35 GHz and the observed performance is examined in light of the critical temperature (Tc) and film thickness and also the film morphology which is different for the two deposition techniques. We find that Tc is a major indicator of the film performance for each growth type with film thickness becoming important as it decreases towards 1000 angstrom. We find that the films with a mixed grain orientation (both 'a' axis and 'c' axis oriented grains) have poorer microwave properties as compared with the primarily 'c' axis oriented material. We speculate that this is due to the significant number of grain boundaries between the different crystallites, which may act as superconducting weak links and contribute to the surface resistance. C1 NASA,CLEVELAND,OH 44135. HUGHES RES LABS,MALIBU,CA 90265. RP CHOREY, CM (reprint author), SVERDRUP TECHNOL,LERC GRP,20001 AEROSP PKWY,BROOK PK,OH 44142, USA. NR 9 TC 2 Z9 2 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 2940 EP 2943 DI 10.1109/20.133825 PN 4 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY654 UT WOS:A1991EY65400097 ER PT J AU LEDUC, HG JUDAS, A CYPHER, SR BUMBLE, B HUNT, BD STERN, JA AF LEDUC, HG JUDAS, A CYPHER, SR BUMBLE, B HUNT, BD STERN, JA TI SUBMICRON AREA NBN/MGO/NBN TUNNEL-JUNCTIONS FOR SIS MIXER APPLICATIONS SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 CONF ON APPLIED SUPERCONDUCTIVITY CY SEP 24-28, 1990 CL SNOWMASS, CO AB We report on progress in the development of submicron area mixer elements for operation in the submillimeter wave range. High current density NbN/MgO/NbN tunnel junctions with areas down to 0.1-mu-m2 have been fabricated in both planar and edge geometries. The planar junctions were fabricated from insitu deposited trilayers using electron-beam lithography to pattern submicron area mesas. Modifications of fabrication techniques used in larger area NbN tunnel junctions are required and will be discussed. The NbN/MgO/NbN edge junction process using sapphire substrates reported earlier has been transferred to technologically important quartz substrates using MgO buffer layers to minimize substrate interactions. The two junction geometries will be compared and contrasted in the context of submillimeter wave mixer applications. RP LEDUC, HG (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 6 TC 15 Z9 15 U1 0 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 3192 EP 3195 DI 10.1109/20.133890 PN 4 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY654 UT WOS:A1991EY65400162 ER PT J AU STERN, JA LEDUC, HG AF STERN, JA LEDUC, HG TI CHARACTERIZATION OF NBN FILMS AND TUNNEL-JUNCTIONS SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article; Proceedings Paper CT 1990 CONF ON APPLIED SUPERCONDUCTIVITY CY SEP 24-28, 1990 CL SNOWMASS, CO ID SIS RECEIVER AB Properties of NbN films and NbN/MgO/NbN tunnel junctions are discussed. NbN junctions are being developed for use in high-frequency, superconductor-insulator-superconductor (SIS) quasiparticle mixers. To properly design mixer circuits, junction and film properties need to be characterized. The specific capacitance of NbN/MgO/NbN junctions has been measured as a function of the product of the normal-state resistance and the junction area (R(n)A), and it is found to vary by more than a factor of two (35-85 fF/mu-m2) over the range of R(n)A measured (1000-50-OMEGA-mu-m2). This variation is important because the specific capacitance determines the RC speed of the tunnel junction at a given R(n)A value. The magnetic penetration depth of NbN films deposited under different conditions is also measured. The magnetic penetration depth affects the design of microstrip line used in RF tuning circuits. Control of the magnetic penetration depth is necessary to fabricate reproducible tuning circuits. Additionally, the critical current uniformity for arrays of 100 junctions has been measured. Junction uniformity will affect the design of focal-plane arrays of SIS mixers. Finally, The relevance of these measurements to the design of Josephson electronics is discussed. RP STERN, JA (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 14 TC 8 Z9 8 U1 2 U2 7 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1991 VL 27 IS 2 BP 3196 EP 3199 DI 10.1109/20.133891 PN 4 PG 4 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA EY654 UT WOS:A1991EY65400163 ER PT J AU TROUDET, T MERRILL, W AF TROUDET, T MERRILL, W TI NEUROMORPHIC LEARNING OF CONTINUOUS-VALUED MAPPINGS FROM NOISE-CORRUPTED DATA SO IEEE TRANSACTIONS ON NEURAL NETWORKS LA English DT Article AB This paper analyzes the effect of noise on the learning performance of the backpropagation algorithm. A selective sampling of the training set is proposed to maximize the learning of continuous-valued mappings by backpropagation, when the data have been corrupted by noise. The training scheme is applied to the nonlinear control of a cart-pole system in the presence of noise. The neural computation provides the neurocontroller with good noise-filtering properties. In the presence of plant noise, the neurocontroller is found to be more stable than the teacher. A novel perspective on the application of neural network technology to control engineering is presented. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP TROUDET, T (reprint author), SVERDRUP TECHNOL,AEROSP PKWY,BROOK PK,OH 44142, USA. NR 13 TC 2 Z9 2 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 1045-9227 J9 IEEE T NEURAL NETWOR JI IEEE Trans. Neural Netw. PD MAR PY 1991 VL 2 IS 2 BP 294 EP 301 DI 10.1109/72.80340 PG 8 WC Computer Science, Artificial Intelligence; Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA FB858 UT WOS:A1991FB85800013 PM 18276383 ER PT J AU SA, JY CHANG, KS AF SA, JY CHANG, KS TI SHEDDING PATTERNS OF THE NEAR-WAKE VORTICES BEHIND A CIRCULAR-CYLINDER SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE CIRCULAR CYLINDER; SHEDDING PATTERNS; SHEDDING FREQUENCY MODES; INTEGRAL SERIES CONDITION ID LOW REYNOLDS-NUMBERS; VORTEX STREETS; BLUFF-BODIES; FLOW; FREQUENCY AB The unsteady incompressible Navier-Stokes equations have been accurately solved for the laminar flow past a circular cylinder in the Reynolds number range 50-200. A direct elliptic solver called the SEVP is used to rapidly advance the streamfunction in time, facilitating the overall convergence to the fully periodic or quasi-steady state. A new integral-series method is developed for the far-field streamfunction condition on a finite two-dimensional computational domain. The use of fourth-order Hermitian relations for the convection terms in the conservation-form vorticity transport equation has also contributed to the good comparison of the present results with the earlier experimental data. The vortex-shedding patterns visualized by the experimentalist are numerically reproduced here in the given Reynolds number range. Discussions that may be helpful in interpreting the behaviour of the shedding frequency are presented in the main text. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SA, JY (reprint author), KOREA ADV INST SCI & TECHNOL,POB 150,SEOUL 131,SOUTH KOREA. NR 37 TC 21 Z9 21 U1 0 U2 2 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0271-2091 J9 INT J NUMER METH FL JI Int. J. Numer. Methods Fluids PD MAR PY 1991 VL 12 IS 5 BP 463 EP 474 DI 10.1002/fld.1650120504 PG 12 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA FC107 UT WOS:A1991FC10700003 ER PT J AU Abraham, RH Corliss, JB Dorband, JE AF Abraham, Ralph H. Corliss, John B. Dorband, John E. TI ORDER AND CHAOS IN THE TORAL LOGISTIC LATTICE SO INTERNATIONAL JOURNAL OF BIFURCATION AND CHAOS LA English DT Article AB Cellular dynamical systems, alias lattice dynamical systems, emerged as a new mathematical structure and modeling strategy in the 1980s. Based, like cellular automata, on finite difference methods for partial differential equations, they provide challenging patterns of spatiotemporal organization, in which chaos and order cooperate in novel ways. Here we present initial findings of our exploration of a two-dimensional logistic lattice with the Massively Parallel Processor (MPP) at NASA's Goddard Space Flight Center, a machine capable of 200 megaflops per second. A video tape illustrating these findings is available. C1 [Abraham, Ralph H.] Univ Calif Santa Cruz, Dept Math, Santa Cruz, CA 95064 USA. [Corliss, John B.] NASA, Goddard Space Flight Ctr, Comp Syst Res Facil, NRC Senior Resident Res Associate, Greenbelt, MD 20771 USA. [Dorband, John E.] NASA, Goddard Space Flight Ctr, Comp Syst Res Facil, Greenbelt, MD 20771 USA. RP Abraham, RH (reprint author), Univ Calif Santa Cruz, Dept Math, Santa Cruz, CA 95064 USA. NR 10 TC 2 Z9 2 U1 1 U2 1 PU WORLD SCIENTIFIC PUBL CO PTE LTD PI SINGAPORE PA 5 TOH TUCK LINK, SINGAPORE 596224, SINGAPORE SN 0218-1274 EI 1793-6551 J9 INT J BIFURCAT CHAOS JI Int. J. Bifurcation Chaos PD MAR PY 1991 VL 1 IS 1 BP 227 EP 234 DI 10.1142/S0218127491000154 PG 8 WC Mathematics, Interdisciplinary Applications; Multidisciplinary Sciences SC Mathematics; Science & Technology - Other Topics GA V44LK UT WOS:000209750300015 ER PT J AU MANKBADI, RR AYAD, SS AF MANKBADI, RR AYAD, SS TI A STUDY OF WAKE-GENERATED UNSTEADINESS IN A CHANNEL FLOW .2. TURBULENCE AND WALL SHEAR-STRESS SO INTERNATIONAL JOURNAL OF ENGINEERING FLUID MECHANICS LA English DT Article AB Results of the effect of wake-passing at the entrance of channel flow on the turbulence and the wall shear stress are presented here. The wake-passing produces large unsteadinesses in the turbulence and the wall shear stress. These unsteadinesses increase with increasing the wake width or the wake amplitude. The time-averaged values of the turbulent stresses and the wall shear stress are not affected by the wake-passing. RP MANKBADI, RR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU GULF PUBL CO PI HOUSTON PA BOX 2608, HOUSTON, TX 77252-2608 SN 0893-3960 J9 INT J ENG FLUID MECH PD SPR PY 1991 VL 4 IS 1 BP 91 EP 110 PG 20 WC Engineering, Chemical; Mechanics; Physics, Fluids & Plasmas SC Engineering; Mechanics; Physics GA GQ053 UT WOS:A1991GQ05300007 ER PT J AU WOOD, BL BECK, LR WASHINO, RK PALCHICK, SM SEBESTA, PD AF WOOD, BL BECK, LR WASHINO, RK PALCHICK, SM SEBESTA, PD TI SPECTRAL AND SPATIAL CHARACTERIZATION OF RICE FIELD MOSQUITO HABITAT SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article AB Irrigated rice provides an ideal breeding habitat for Anopheles free-borni, the western malaria mosquito, throughout California. In a 1985 study, it was determined that early-season rice canopy development, as monitored using remotely sensed data, could be used to distinguish between high and low mosquito producing rice fields. This distinction could be made over two months prior to peak mosquito production. It was also found that high-producing fields were located in an area characterized by a diversity of land use, including livestock pastures, whereas the low-producing fields were in an area devoted almost exclusively to the cultivation of rice. The ability to distinguish between high and low mosquito producing fields prior to peak mosquito production is important in terms of mosquito habitat surveillance and control. C1 UNIV CALIF DAVIS,DEPT ENTOMOL,DAVIS,CA 95616. RP WOOD, BL (reprint author), NASA,AMES RES CTR,TGS TECHNOL INC,MS 242-4,MOFFETT FIELD,CA 94035, USA. NR 11 TC 33 Z9 38 U1 0 U2 6 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 MAR PY 1991 VL 12 IS 3 BP 621 EP 626 PG 6 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA EZ885 UT WOS:A1991EZ88500019 ER PT J AU RHEA, WJ AF RHEA, WJ TI A NEW TECHNIQUE FOR ENLARGEMENT AND RECONSTRUCTION OF DIGITAL SENSOR IMAGERY SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID CUBIC CONVOLUTION AB A new image enlargement and reconstruction routine, the digital image enlarging balanced reconstruction algorithm (DIEBRA), is described. Using a highly modified form of 'balanced' two-dimensional polynomial interpolation, this program enlarges digital imagery, creating synthetic high spatial resolution images. Statistical analysis shows the DIEBRA-generated imagery to be significantly closer to true high spatial resolution imagery at all frequencies than imagery generated by a cubic convolutional reconstruction filter. RP RHEA, WJ (reprint author), CALTECH,JET PROP LAB,MAIL STOP 300-323,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 TC 2 Z9 2 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 MAR PY 1991 VL 12 IS 3 BP 627 EP 634 PG 8 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA EZ885 UT WOS:A1991EZ88500020 ER PT J AU BENNETT, RM BLAND, SR BATINA, JT GIBBONS, MD MABEY, DG AF BENNETT, RM BLAND, SR BATINA, JT GIBBONS, MD MABEY, DG TI CALCULATION OF STEADY AND UNSTEADY PRESSURES ON WINGS AT SUPERSONIC SPEEDS WITH A TRANSONIC SMALL-DISTURBANCE CODE SO JOURNAL OF AIRCRAFT LA English DT Article AB A transonic unsteady aerodynamic and aeroelasticity code has been developed for application to realistic aircraft configurations. The code is called CAP-TSD (computational aeroelasticity program-transonic small-disturbance) and uses a time-accurate approximate factorization algorithm for solution of the unsteady transonic small-disturbance equation that is efficient for solution of steady and unsteady transonic flow problems including supersonic freestream flows. This code can treat complete aircraft geometries with multiple lifting surfaces and bodies. Applications to wings in supersonic freestream flow are presented. Comparisons with selected exact solutions from linear theory are presented, showing generally favorable results. Calculations for both steady and oscillatory cases for the F-5 wing and the Royal Aerospace Establishment tailplane models are compared with experimental data and also show good overall agreement. Selected steady calculations are also compared with the results from a steady flow Euler code. RP BENNETT, RM (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,UNSTEADY AERODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 0 TC 2 Z9 2 U1 1 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAR PY 1991 VL 28 IS 3 BP 175 EP 180 DI 10.2514/3.46009 PG 6 WC Engineering, Aerospace SC Engineering GA FP695 UT WOS:A1991FP69500004 ER PT J AU RANAUDO, RJ BATTERSON, JG REEHORST, AL BOND, TH OMARA, TM AF RANAUDO, RJ BATTERSON, JG REEHORST, AL BOND, TH OMARA, TM TI EFFECTS OF HORIZONTAL TAIL ICE ON LONGITUDINAL AERODYNAMIC DERIVATIVES SO JOURNAL OF AIRCRAFT LA English DT Article AB Flight tests were performed with the NASA Lewis Research Center's DH-6 icing research aircraft to determine the accuracy with which the effects of ice on aircraft longitudinal stability and control could be measured. Flights were made with both a clean (baseline) configuration and with simulated ice on the horizontal tail. At a given trim speed 45 repeat doublet maneuvers were performed in each of four test configurations to determine the ensemble variation of the estimated stability and control derivatives. Additional maneuvers were also performed in each configuration to determine the variation in the longitudinal derivative estimates over a wide range of trim speeds. Stability and control derivatives were estimated by a modified stepwise regression (MSR) technique. A measure of the confidence in the derivative estimates was obtained by comparing the standard error for the ensemble of repeat maneuvers to the average of the estimated standard errors predicted by the MSR program. The magnitude of icing effects on the derivative estimates was strongly dependent on flight speed and aircraft wing flap configuration. With wing flaps up, the estimated derivatives were degraded most at lower speeds corresponding to that configuration. With wing flaps extended to 10 deg, the estimated derivatives were degraded most at the higher corresponding speeds. RP RANAUDO, RJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAR PY 1991 VL 28 IS 3 BP 193 EP 199 DI 10.2514/3.46012 PG 7 WC Engineering, Aerospace SC Engineering GA FP695 UT WOS:A1991FP69500007 ER PT J AU MALONE, JB NARRAMORE, JC SANKAR, LN AF MALONE, JB NARRAMORE, JC SANKAR, LN TI AIRFOIL DESIGN METHOD USING THE NAVIER-STOKES EQUATIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB An airfoil design procedure is described that has been incorporated into an existing two-dimensional Navier-Stokes airfoil analysis method. The resulting design method, an iterative procedure based on a residual-correction algorithm, permits the automated design of airfoil sections with prescribed surface pressure distributions. This paper describes the inverse design method and the technique used to specify target pressure distributions. It presents several example problems to demonstrate application of the design procedure. These examples illustrate that the inverse design method can be used to develop useful airfoil configurations with a reasonable expenditure of computer resources. RP MALONE, JB (reprint author), NASA,LANGLEY RES CTR,UNSTEADY AERODYNAM BRANCH,HAMPTON,VA 23665, USA. NR 0 TC 21 Z9 25 U1 1 U2 3 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 MAR PY 1991 VL 28 IS 3 BP 216 EP 224 DI 10.2514/3.46015 PG 9 WC Engineering, Aerospace SC Engineering GA FP695 UT WOS:A1991FP69500010 ER PT J AU SERBETCI, I TICHY, JA AF SERBETCI, I TICHY, JA TI INERTIA EFFECTS IN THIN-FILM FLOW WITH A CORRUGATED BOUNDARY SO JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME LA English DT Article AB An analytical solution is presented for two-dimensional, incompressible film flow between a sinusoidally grooved (or rough) surface and a flat surface. The upper grooved surface is stationary whereas the lower, smooth surface moves with a constant speed. The Navier-Strokes equations were solved employing both mapping techniques and perturbation expansions. Due to the inclusion of the inertia effects, a different pressure distribution is obtained than predicted by the classical lubrication theory. In particular, the amplitude of the pressure distribution of the classical lubrication theory is found to be in error by over 100 percent (for modified Reynolds number of 3-4). C1 NASA,LEWIS RES CTR,DIV SPACE PROP TECHNOL,CLEVELAND,OH 44735. RENSSELAER POLYTECH INST,DEPT MECH ENGN,TROY,NY 12181. NR 15 TC 3 Z9 3 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0021-8936 J9 J APPL MECH-T ASME JI J. Appl. Mech.-Trans. ASME PD MAR PY 1991 VL 58 IS 1 BP 272 EP 277 DI 10.1115/1.2897163 PG 6 WC Mechanics SC Mechanics GA HP715 UT WOS:A1991HP71500040 ER PT J AU HASLER, AF STRONG, J WOODWARD, RH PIERCE, H AF HASLER, AF STRONG, J WOODWARD, RH PIERCE, H TI AUTOMATIC-ANALYSIS OF STEREOSCOPIC SATELLITE IMAGE PAIRS FOR DETERMINATION OF CLOUD-TOP HEIGHT AND STRUCTURE SO JOURNAL OF APPLIED METEOROLOGY LA English DT Article ID FIELDS AB A massively parallel processor (MPP) computer has made it practical to do automatic stero analysis of cloud-top heights from stereoscopic satellite image pairs. The automatic analysis is of equivalent quality to manual analysis while taking several orders of magnitude less time. The height of large-scale structure can be measured more accurately with the automatic analysis, but the height of small-scale towers are underestimated. Simulations using synthetic stereo data show that it is possible to automatically resolve small-scale features (e.g., 4000-m diameter clouds) to about 1500 m in the vertical. Nearly simultaneous image pairs from the GOES and NOAA satellites of hurricanes and tornadic thunderstorm clouds are used to demonstrate automatic analysis on real stereo data. Quality problems with the real stereo data require courser automatic analysis with a minimum scale size of 10 000 m. Higher quality GOES-Next stereoscopic image pairs, expected to be routinely available in the next few years should make useful operational automatic stereo cloud-height measurements practical. Some possible applications of the automatic stereo include severe storm and hurricane nowcasting, aviation forecasting and development of cloud climatologies. C1 NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,GREENBELT,MD 20771. GEN SCI CORP,LAUREL,MD. RP HASLER, AF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 973,GREENBELT,MD 20771, USA. NR 18 TC 20 Z9 25 U1 0 U2 2 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8763 J9 J APPL METEOROL JI J. Appl. Meteorol. PD MAR PY 1991 VL 30 IS 3 BP 257 EP 281 DI 10.1175/1520-0450(1991)030<0257:AAOSSI>2.0.CO;2 PG 25 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FJ114 UT WOS:A1991FJ11400001 ER PT J AU MELBOURNE, RK PRESTAGE, JD MALEKI, L AF MELBOURNE, RK PRESTAGE, JD MALEKI, L TI ANALYTIC POTENTIAL IN A LINEAR RADIOFREQUENCY QUADRUPOLE TRAP WITH CYLINDRICAL ELECTRODES SO JOURNAL OF APPLIED PHYSICS LA English DT Article AB We have analyzed a linear radio-frequency ion trap of finite length employing a four-sectored hollow cylinder enclosed between two end caps. Solutions to Laplace's equation determine the effective potential inside the trap due to the rf trapping field, the static confining potential from dc-biased end caps, and the potential arising when a dc bias is present on the cylinder sectors. The finite length of a linear trap results in field distortion at the trap ends due to fringing effects. We have demonstrated that near the ends, the effective potential arising from the rf fields acts to propel ions out of the trap. We have further shown that the addition of a dc bias on two neighboring cylinder sectors generates an inhomogeneous field in the trap which produces a force on the ions along the trap's long axis in a direction dependent on the sign of the bias. An exact analytic determination of the potential can be used to determine the profile of the trapped ion cloud. RP MELBOURNE, RK (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 8 TC 5 Z9 5 U1 3 U2 4 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-8979 J9 J APPL PHYS JI J. Appl. Phys. PD MAR 1 PY 1991 VL 69 IS 5 BP 2768 EP 2775 DI 10.1063/1.348635 PG 8 WC Physics, Applied SC Physics GA FA705 UT WOS:A1991FA70500002 ER PT J AU KIM, KH VENABLE, DD BROWN, LA LEE, JH AF KIM, KH VENABLE, DD BROWN, LA LEE, JH TI THERMAL EFFECTS ON CAVITY STABILITY OF CHROMIUM-DOPED AND NEODYMIUM-DOPED GADOLINIUM SCANDIUM GALLIUM GARNET LASER UNDER SOLAR-SIMULATOR PUMPING SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID CR-3+ SENSITIZED ND-3+; CR-ND-GSGG; GDSCGA-GARNET; YAG AB A chromium- and neodymium-codoped gadolinium scandium gallium garnet (Cr:Nd:GSGG) crystal was tested for pulsed- and continuous-wave (cw) laser operations with a flashlamp and solar simulator as pumping sources. The crystal has been considered as a good candidate for a solar-pumped laser because of its broad absorption bands over the solar spectrum. However, it was observed experimentally and theoretically that its cw laser operation is difficult at high pump powers because too many thermal lensing effects are induced. Only at low solar-simulator beam intensities of up to 1500 solar constants (203 W/cm2) was cw laser operation lasting longer than 10 min achieved. For higher pump beam intensities of up to 2500 solar constants (338 W/cm2), a quasi-cw-laser operation was obtained with continuously chopped pumping with a duty cycle of 0.5 and a repetition rate of 13 Hz. The experimental result was compared with the calculated stability condition of the laser resonator for various pump powers and showed that the thermal focusing of the Cr:Nd:GSGG is 15-8 times greater than that of the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for the pump beam intensities from 1000 to 3000 solar constants. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. HAMPTON UNIV,DEPT PHYS,HAMPTON,VA 23668. RP KIM, KH (reprint author), ELECTR & TELECOMMUN RES INST,POB 8,TAEJON,SOUTH KOREA. NR 20 TC 5 Z9 5 U1 0 U2 2 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 MAR 1 PY 1991 VL 69 IS 5 BP 2841 EP 2848 DI 10.1063/1.348619 PG 8 WC Physics, Applied SC Physics GA FA705 UT WOS:A1991FA70500012 ER PT J AU ALAJAJIAN, SH MAN, KF CHUTJIAN, A AF ALAJAJIAN, SH MAN, KF CHUTJIAN, A TI ELECTRON-ATTACHMENT LINE-SHAPES, CROSS-SECTIONS, AND RATE CONSTANTS AT ULTRALOW ENERGIES IN CF3SO3H, (CF3SO2)2O, AND CF3I SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID PERFLUOROALKANES; MOLECULES; CCL4; CH3I; SF6 AB Electron attachment cross sections are reported in the energy range 0-160 meV, and at resolutions of 6.0-6.5 meV (FWHM) for the molecules CF3SO3H (triflic acid), (CF3SO2)2O (triflic anhydride), and CF3I (methyl iodide). Use is made of the Kr photoionization method. Attachment line shapes are deconvoluted from the spectral slit (electron energy) function, and are converted to cross sections by normalization to thermal attachment rate constants at 300 K. Rate constants as a function of mean electron energy are calculated from the cross sections using a Maxwellian electron energy distribution function. Present data are compared with flowing-afterglow, Langmuir-probe (FALP) results in triflic acid and anhydride, and with high-Rydberg ionization results in CF3I. RP ALAJAJIAN, SH (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 19 TC 12 Z9 12 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD MAR 1 PY 1991 VL 94 IS 5 BP 3629 EP 3632 DI 10.1063/1.460687 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FA778 UT WOS:A1991FA77800037 ER PT J AU CHONG, DP LANGHOFF, SR BAUSCHLICHER, CW AF CHONG, DP LANGHOFF, SR BAUSCHLICHER, CW TI THEORETICAL-STUDY OF THE HYPERFINE PARAMETERS OF OH SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID EXCITED UPSILON-LESS-THAN-OR-EQUAL-TO-6 LEVELS; MANY-BODY CALCULATIONS; MICROWAVE-SPECTRUM; DIATOMIC-MOLECULES; 1ST-ROW HYDRIDES; BASIS SETS; CONSTANTS; CONTRACTION; VALUES; CI(SD) AB The magnetic hyperfine parameters of (OH)-O-17 are studied as a function of the one- and n-particle spaces. All of the parameters, except the spin density on oxygen, b(F)(O), are well described by modest levels of theory. Thus, we have directed much of our effort to understanding the computational requirements for accurately determining b(F)(O). Full configuration-interaction (FCI) calculations in six Gaussian basis sets give unambiguous results for the effect of uncontracting the oxygen s and p basis sets, of adding diffuse s and p functions, and of adding polarization functions to oxygen. FCI calculations in a [6s 2p 1d /2s] contracted basis give a b(F)(O) value that is in good agreement with experiment. A critical factor in any n-particle treatment is a balanced treatment of core and valence correlation. The size-extensive modified coupled-pair functional method provides b(F) values in reasonably good agreement with the FCI. Methods that account quantitatively for the valence correlation, such as complete-active-space self-consistent-field/multireference configuration interaction, appear to introduce an imbalance between core and valence contributions to b(F) when the one-particle basis sets are flexibly contracted in the core. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CHONG, DP (reprint author), UNIV BRITISH COLUMBIA,DEPT CHEM,VANCOUVER V6T 1Y6,BC,CANADA. NR 32 TC 21 Z9 21 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 MAR 1 PY 1991 VL 94 IS 5 BP 3700 EP 3706 DI 10.1063/1.459740 PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA FA778 UT WOS:A1991FA77800045 ER PT J AU MITAL, SK CHAMIS, CC AF MITAL, SK CHAMIS, CC TI FIBER PUSHOUT TEST - A 3-DIMENSIONAL FINITE-ELEMENT COMPUTATIONAL SIMULATION SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE FIBERS; INTERFACE; INTERPHASE; PUSHTHROUGH; PUSHOUT; SHEAR STRENGTH; BONDING; SIMULATION; RESIDUAL STRESS; THERMAL STRESS ID CERAMIC COMPOSITES; MATRIX COMPOSITES AB A fiber pushthrough process has been computationally simulated using a three-dimensional (3-D) finite element method. The interphase material is replaced by an anisotropic material with greatly reduced shear modulus, such that the simulation becomes linear up to the fiber pushthrough load. Such a procedure is easily implemented and is computationally very effective. It can be used to predict fiber pushthrough load for a composite system at any temperature. The average interface shear strength obtained from pushthrough load can easily be separated into its two components: one that comes from frictional stresses and the other that comes from chemical adhesion between fiber and the matrix and mechanical interlocking that develops as a result of shrinkage of the composite because of phase change during the processing. Step-by-step procedures are described to perform the computational simulation, to establish bounds on interfacial bond, and to interpret interfacial bond quality. C1 NASA,LEWIS RES CTR,INST COMPUTAT MECH PROPULS,CLEVELAND,OH 44135. NR 14 TC 9 Z9 9 U1 2 U2 2 PU AMER SOC TESTING MATERIALS PI W CONSHOHOCKEN PA 100 BARR HARBOR DR, W CONSHOHOCKEN, PA 19428-2959 SN 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD SPR PY 1991 VL 13 IS 1 BP 14 EP 21 PG 8 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA FD839 UT WOS:A1991FD83900002 ER PT J AU BAILEY, HE BEAM, RM AF BAILEY, HE BEAM, RM TI NEWTON METHOD APPLIED TO FINITE-DIFFERENCE APPROXIMATIONS FOR THE STEADY-STATE COMPRESSIBLE NAVIER-STOKES EQUATIONS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID FLOW; BODIES RP BAILEY, HE (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 11 TC 12 Z9 12 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 MAR PY 1991 VL 93 IS 1 BP 108 EP 127 DI 10.1016/0021-9991(91)90075-V PG 20 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA FE379 UT WOS:A1991FE37900002 ER PT J AU PUSEY, ML AF PUSEY, ML TI ESTIMATION OF THE INITIAL EQUILIBRIUM-CONSTANTS IN THE FORMATION OF TETRAGONAL LYSOZYME NUCLEI SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID EGG-WHITE LYSOZYME; MEMBRANE ATTACK COMPLEX; GROWTH-KINETICS; CRYSTAL-GROWTH; PROTEIN CRYSTALLIZATION; LIGHT-SCATTERING; SELF-ASSOCIATION; RESOLUTION; SOLUBILITY; NUCLEATION AB Knowledge of the solution aggregate composition in both undersaturated (pre-nucleated) and oversaturated (nucleated and crystal growing) solutions is important to the eventual understanding of the (protein) crystal nucleation and growth process. Using relative light scattering intensity measurements at 90-degrees, estimates of the initial equilibrium constants in the formation of tetragonal lysozyme nuclei have been made. While the aggregation pathway is not known, it is assumed that the first step is dimer formation (K1 = [P2]/[P1]2). Experiments at 3.0% NaCl, 0.1M acetate buffer, pH 4.0, 22-degrees-C indicate K1 values of (1-3) x 10(4) L mol-1. Estimation of subsequent equilibrium constants will be dependent upon the aggregation model chosen or determined. For a 1 --> 2 --> 4 pathway, K2 values are estimated to be (2-4) x 10(3) L mol-1, while for a 1 --> 2 --> 3 pathway, values of (10-20) x 10(3) L mol-1 are estimated. Equilibrium values of this magnitude essentially "fix" the monomer concentration by the saturation concentration point, with only the higher order aggregates showing appreciable concentration increase with increasing total protein concentration. This strongly suggests that tetragonal lysozyme crystal growth is by addition of aggregates preformed in the bulk solution, not by monomer addition. This is independent of a screw dislocation or surface nucleation type mechanism. RP PUSEY, ML (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH,E576,HUNTSVILLE,AL 35812, USA. NR 43 TC 52 Z9 52 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAR PY 1991 VL 110 IS 1-2 BP 60 EP 65 DI 10.1016/0022-0248(91)90866-4 PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA FF694 UT WOS:A1991FF69400008 ER PT J AU CACIOPPO, E MUNSON, S PUSEY, ML AF CACIOPPO, E MUNSON, S PUSEY, ML TI PROTEIN SOLUBILITIES DETERMINED BY A RAPID TECHNIQUE AND MODIFICATION OF THAT TECHNIQUE TO A MICROMETHOD SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID CRYSTAL-GROWTH; LYSOZYME; CRYSTALLIZATION; KINETICS AB This laboratory has developed a simple, rapid method for determination of protein solubilities [Pusey and Gernert, J. Crystal Growth 88 (1988) 419]. The system was based upon maximization of the available crystalline surface area and minimization of the free solution volume to be brought into equilibrium. We have determined the tetragonal lysozyme solubility diagram from pH 4.0 to 5.2 (0.1 M sodium acetate), 2%-7% NaCl, 3-25-degrees-C, and portions of the orthorhombic solubility diagram using this technique. Both the tetragonal and orthorhombic solubilities were found to increase smoothly with decreasing salt concentration and increasing temperature. No retrograde solubilities were observed. A major drawback was a requirement for 1-5 mL (ca. 0.5 to 2.5 g) of crystalline protein per column, leading to the devising of micro-methods for implementing this technique. Using column volumes of 75, 300, and 900-mu-L, identical tetragonal lysozyme solubility diagrams (pH 4.5, 0.1M sodium acetate, 5-25-degrees-C) were obtained. Chymotrypsinogen solubilities have also been determined using this apparatus, being retrograde over the temperature range tested. Currently, the primary limiting factor in reducing the crystalline volume is the minimum solution sample size needed to accurately quantitate the protein. C1 UNIV WISCONSIN,DEPT BACTERIOL,MADISON,WI 53706. RP CACIOPPO, E (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH,ES76,HUNTSVILLE,AL 35812, USA. NR 16 TC 67 Z9 67 U1 1 U2 11 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 MAR PY 1991 VL 110 IS 1-2 BP 66 EP 71 DI 10.1016/0022-0248(91)90867-5 PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA FF694 UT WOS:A1991FF69400009 ER PT J AU RHIM, WK CHUNG, SK AF RHIM, WK CHUNG, SK TI CONTAINERLESS PROTEIN CRYSTAL-GROWTH METHOD SO JOURNAL OF CRYSTAL GROWTH LA English DT Article AB A method of growing protein crystals from levitated drops is introduced and unique features of containerless approach in 1-g and mu-g laboratories are discussed. Electrostatic multi-drop levitation system which is capable of simultaneous four drop levitation is described. A method of controlling protein saturation level in a programmed way is introduced and discussed. Finally, some of the unique features of containerless approach of protein crystal growth in space are discussed and summarized. RP RHIM, WK (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 8 TC 15 Z9 16 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 MAR PY 1991 VL 110 IS 1-2 BP 293 EP 301 DI 10.1016/0022-0248(91)90898-F PG 9 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA FF694 UT WOS:A1991FF69400040 ER PT J AU DELUCAS, LJ SMITH, CD SMITH, W VIJAYKUMAR, S SENADHI, SE EALICK, SE CARTER, DC SNYDER, RS WEBER, PC SALEMME, FR OHLENDORF, DH EINSPAHR, HM CLANCY, LL NAVIA, MA MCKEEVER, BM NAGABHUSHAN, TL NELSON, G MCPHERSON, A KOSZELAK, S TAYLOR, G STAMMERS, D POWELL, K DARBY, G BUGG, CE AF DELUCAS, LJ SMITH, CD SMITH, W VIJAYKUMAR, S SENADHI, SE EALICK, SE CARTER, DC SNYDER, RS WEBER, PC SALEMME, FR OHLENDORF, DH EINSPAHR, HM CLANCY, LL NAVIA, MA MCKEEVER, BM NAGABHUSHAN, TL NELSON, G MCPHERSON, A KOSZELAK, S TAYLOR, G STAMMERS, D POWELL, K DARBY, G BUGG, CE TI PROTEIN CRYSTAL-GROWTH RESULTS FOR SHUTTLE FLIGHTS STS-26 AND STS-29 SO JOURNAL OF CRYSTAL GROWTH LA English DT Article AB Recent advances in protein crystallography have significantly shortened the time and labor required to determine the three-dimensional structures of macromolecules once good crystals are available. Crystal growth has become a major bottleneck in further development of protein crystallography. Proteins and other biological macromolecules are notoriously difficult to crystallize. Even when usable crystals are obtained, the crystals of essentially all proteins and other biological macromolecules are poorly ordered, and diffract to resolutions considerably lower than that available for most crystals of simple organic and inorganic compounds. One promising area of research which is receiving widespread attention is protein crystal growth in the microgravity environment of space. A series of protein crystal growth experiments were performed on US shuttle flight STS-26 in September 1988 and STS-29 in March 1989. These proteins had been studied extensively in crystal growth experiments on earth prior to the microgravity experiments. For those proteins which produced crystals of adequate size, three-dimensional intensity data sets with electronic area detector systems were collected. Comparisons of the microgravity-grown crystals with the best earth-grown crystals obtained in numerous experiments demonstrate that the microgravity-grown crystals of these proteins are larger, display more uniform morphologies, and yield diffraction data to significantly higher resolutions. Analyses of the three-dimensional data sets by relative-Wilson plots indicate that the space-grown crystals are more highly ordered at the molecular level than their earth-grown counterparts. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UPJOHN CO,KALAMAZOO,MI 49001. MERCK SHARP & DOHME LTD,RAHWAY,NJ 07065. SCHERING PLOUGH CORP,BLOOMFIELD,NJ 07003. UNIV WASHINGTON,DEPT ASTRON,SEATTLE,WA 98195. UNIV CALIF RIVERSIDE,RIVERSIDE,CA 92521. UNIV OXFORD,MOLEC BIOPHYS LAB,OXFORD OX1 3QU,ENGLAND. WELLCOME RES LABS,BECKENHAM BR3 3BS,KENT,ENGLAND. DUPONT CO,DEPT CENT RES & DEV,WILMINGTON,DE 19880. RP DELUCAS, LJ (reprint author), UNIV ALABAMA,CTR MACROMOLEC CRYSTALLOG,POB 79 THT,UAB STN,BIRMINGHAM,AL 35294, USA. NR 11 TC 33 Z9 33 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAR PY 1991 VL 110 IS 1-2 BP 302 EP 311 DI 10.1016/0022-0248(91)90899-G PG 10 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA FF694 UT WOS:A1991FF69400041 ER PT J AU SNYDER, RS FUHRMANN, K WALTER, HU AF SNYDER, RS FUHRMANN, K WALTER, HU TI PROTEIN CRYSTALLIZATION FACILITIES FOR MICROGRAVITY EXPERIMENTS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID CRYSTAL-GROWTH AB The first experiments demonstrating the enhancement of protein crystallization in microgravity were performed on the European Space Agency's first Spacelab mission in 1983 using the liquid/liquid interface diffusion technique and this experiment method will be continued on the European Retrievable Carrier. The current facility from the National Aeronautics and Space Administration employs a modified version of the "hanging drop" or the vapor diffusion technique. Protein crystal growth programs of NASA, ESA, and other national space programs now utilize a variety of instrumentation, and new methods are being developed to grow and study crystals of biological macromolecules in microgravity. This paper summarizes the present status of the NASA Vapor Diffusion Apparatus and ESA Protein Crystallization Facility. C1 EUROPEAN SPACE TECHNOL CTR,DIV MICROGRAV,2200 AG NOORDWIJK,NETHERLANDS. EUROPEAN SPACE AGCY,DIRECTORATE EARTH OBSERVAT & MICROGRAV,MICROGRAV OFF,F-75738 PARIS 15,FRANCE. RP SNYDER, RS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 7 TC 32 Z9 32 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAR PY 1991 VL 110 IS 1-2 BP 333 EP 338 DI 10.1016/0022-0248(91)90903-I PG 6 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA FF694 UT WOS:A1991FF69400045 ER PT J AU KNUTESON, DJ FRIPP, AL WOODELL, GA DEBNAM, WJ NARAYANAN, R AF KNUTESON, DJ FRIPP, AL WOODELL, GA DEBNAM, WJ NARAYANAN, R TI UNSTEADY CONVECTION IN TIN IN A BRIDGMAN CONFIGURATION SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID CRYSTAL-GROWTH; INSTABILITIES; NUMBER AB When a quiescent fluid is heated sufficiently from below, steady convection will begin. Further heating will cause oscillatory and then turbulent flow. Theoretical results predict that the frequency of oscillation will depend on the square root of the Rayleigh number in the fluid. In the current work, liquid tin was heated from below for three aspect ratios, h/R = 3.4, 5.3, and 7.0. The experimental results are curve-fit for the square-root relation and also for a linear relation. The fit of the expression is evaluated using a correlation coefficient. An estimate for the first critical Rayleigh number (onset of steady convection) is obtained for both expressions. These values are compared to previous experimental results. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. UNIV FLORIDA,DEPT CHEM ENGN,GAINESVILLE,FL 32611. NR 14 TC 1 Z9 1 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 MAR PY 1991 VL 110 IS 3 BP 348 EP 352 DI 10.1016/0022-0248(91)90270-F PG 5 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA FF965 UT WOS:A1991FF96500002 ER PT J AU COBB, SD ANDREWS, RN SZOFRAN, FR LEHOCZKY, SL AF COBB, SD ANDREWS, RN SZOFRAN, FR LEHOCZKY, SL TI CHARACTERIZATION OF DIRECTIONALLY SOLIDIFIED HG1-XZNXSE SEMICONDUCTING ALLOYS SO JOURNAL OF CRYSTAL GROWTH LA English DT Article ID COMPOSITIONAL VARIATIONS; HGCDTE ALLOYS; GROWTH; SEGREGATION; CDXHG1-XTE; SYSTEM AB Hg(1-x)Zn(x)Se alloys with composition between x = 0.08 and 0.115 were synthesized from elemental constituents and were resolidified using a Bridgman-Stockbarger growth technique. By performing precision mass-density measurements on selected wafers cut perpendicular to the growth axis, it was shown that the axial compositional profiles fit a numerical solution to the one-dimensional diffusion equation which takes into account the variation of interface velocity with time. Infrared transmission edge measurements performed on selected transverse slices from each ingot showed that the relative radial variations in composition decreased with decreasing growth rate. Van der Pauw measurements on selected wafers showed that the 10(18) cm-3 electron concentration, typical of as-grown crystals, could be reduced by approximately an order of magnitude by annealing in Se vapor. C1 UNIV ALABAMA,FACHBEREICH MAT SCI & ENGN,BIRMINGHAM,AL 35294. RP COBB, SD (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 23 TC 10 Z9 10 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-0248 J9 J CRYST GROWTH JI J. Cryst. Growth PD MAR PY 1991 VL 110 IS 3 BP 415 EP 422 DI 10.1016/0022-0248(91)90277-C PG 8 WC Crystallography; Materials Science, Multidisciplinary; Physics, Applied SC Crystallography; Materials Science; Physics GA FF965 UT WOS:A1991FF96500009 ER PT J AU MANNESTO, G LOOMIS, JB AF MANNESTO, G LOOMIS, JB TI EVALUATION OF MAIL AND IN-PERSON CONTINGENT VALUE SURVEYS - RESULTS OF A STUDY OF RECREATIONAL BOATERS SO JOURNAL OF ENVIRONMENTAL MANAGEMENT LA English DT Article DE RECREATION; BOATING; CONTINGENT VALUE SURVEYS ID VALUATION C1 UNIV CALIF DAVIS, DIV ENVIRONM STUDIES, DAVIS, CA 95616 USA. NATL MARINE FISHERIES SERV, GLOUCESTER, MA 01930 USA. NR 19 TC 17 Z9 18 U1 3 U2 3 PU ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD PI LONDON PA 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND SN 0301-4797 EI 1095-8630 J9 J ENVIRON MANAGE JI J. Environ. Manage. PD MAR PY 1991 VL 32 IS 2 BP 177 EP 190 DI 10.1016/S0301-4797(05)80032-5 PG 14 WC Environmental Sciences SC Environmental Sciences & Ecology GA FC084 UT WOS:A1991FC08400006 ER PT J AU SANDHAM, ND REYNOLDS, WC AF SANDHAM, ND REYNOLDS, WC TI 3-DIMENSIONAL SIMULATIONS OF LARGE EDDIES IN THE COMPRESSIBLE MIXING LAYER SO JOURNAL OF FLUID MECHANICS LA English DT Article ID TURBULENT SHEAR-LAYER AB The effect of Mach number on the evolution of instabilities in the compressible mixing layer is investigated. The full time-dependent compressible Navier-Stokes equations are solved numerically for a temporally evolving mixing layer using a mixed spectral and high-order finite difference method. The convective Mach number M(c) (the ratio of the velocity difference to the sum of the free-stream sound speeds) is used as the compressibility parameter. Simulations with random initial conditions confirm the prediction of linear stability theory that at high Mach numbers (M(c) > 0.6) oblique waves grow more rapidly than two-dimensional waves. Simulations are then presented of the nonlinear temporal evolution of the most rapidly amplified linear instability waves. A change in the developed large-scale structure is observed as the Mach number is increased, with vortical regions oriented in a more oblique manner at the higher Mach numbers. At convective Mach numbers above unity the two-dimensional instability is found to have little effect on the flow development, which is dominated by the oblique instability waves. The nonlinear structure which develops from a pair of equal and opposite oblique instability waves is found to resemble a pair of inclined LAMBDA-vortices which are staggered in the streamwise direction. A fully nonlinear computation with a random initial condition shows the development of large-scale structure similar to the simulations with forcing. It is concluded that there are strong compressibility effects on the structure of the mixing layer and that highly three-dimensional structures develop from the primary inflexional instability of the flow at high Mach numbers. C1 STANFORD UNIV,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SANDHAM, ND (reprint author), DLR,INST THEORET FLUID MECH,GOTTINGEN,GERMANY. RI Sandham, Neil/G-4755-2010 NR 32 TC 161 Z9 168 U1 0 U2 16 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 MAR PY 1991 VL 224 BP 133 EP 158 DI 10.1017/S0022112091001684 PG 26 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FG991 UT WOS:A1991FG99100007 ER PT J AU LUNDGREN, TS MANSOUR, NN AF LUNDGREN, TS MANSOUR, NN TI VORTEX RING BUBBLES SO JOURNAL OF FLUID MECHANICS LA English DT Article ID LIQUID AB Toroidal bubbles with circulation are studied numerically and by means of a physically motivated model equation. Two series of computations are performed by a boundary-integral method. One set shows the starting motion of an initially spherical bubble as a gravitationally driven liquid jet penetrates through the bubble from below causing a toroidal geometry to develop. The jet becomes broader as surface tension increases and fails to penetrate if surface tension is too large. The dimensionless circulation that develops is not very dependent on the surface tension. The second series of computations starts from a toroidal geometry, with circulation determined from the earlier series, and follows the motion of the rising and spreading vortex ring. Some modifications to the boundary-integral formulation were devised to handle the multiply connected geometry. The computations uncovered some unexpected rapid oscillations of the ring radius. These oscillations and the spreading of the ring are explained by the model equation which provides a more general description of vortex ring bubbles than previously available. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP LUNDGREN, TS (reprint author), UNIV MINNESOTA,DEPT AEROSP ENGN & MECH,MINNEAPOLIS,MN 55455, USA. NR 21 TC 64 Z9 71 U1 1 U2 14 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 MAR PY 1991 VL 224 BP 177 EP 196 DI 10.1017/S0022112091001702 PG 20 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FG991 UT WOS:A1991FG99100009 ER PT J AU JOHANSSON, AV ALFREDSSON, PH KIM, J AF JOHANSSON, AV ALFREDSSON, PH KIM, J TI EVOLUTION AND DYNAMICS OF SHEAR-LAYER STRUCTURES IN NEAR-WALL TURBULENCE SO JOURNAL OF FLUID MECHANICS LA English DT Article ID BOUNDARY-LAYER; CHANNEL FLOW; SPATIAL-RESOLUTION; VISCOUS SUBLAYER; PRESSURE; EVENTS; REGION AB Near-wall flow structures in turbulent shear flows are analysed, with particular emphasis on the study of their space-time evolution and connection to turbulence production. The results are obtained from investigation of a database generated from direct numerical simulation of turbulent channel flow at a Reynolds number of 180 based on half-channel width and friction velocity. New light is shed on problems associated with conditional sampling techniques, together with methods to improve these techniques, for use both in physical and numerical experiments. The results clearly indicate that earlier conceptual models of the processes associated with nearwall turbulence production, based on flow visualization and probe measurements need to be modified. For instance, the development of asymmetry in the spanwise direction seems to be an important element in the evolution of near-wall structures in general, and for shear layers in particular. The inhibition of spanwise motion of the near-wall streaky pattern may be the primary reason for the ability of small longitudinal riblets to reduce turbulent skin friction below the value for a flat surface. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP JOHANSSON, AV (reprint author), ROYAL INST TECHNOL,DEPT MECH,S-10044 STOCKHOLM 70,SWEDEN. OI Alfredsson, P. Henrik/0000-0002-1146-3241; Kim, John/0000-0002-6369-9264 NR 40 TC 100 Z9 101 U1 0 U2 4 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 MAR PY 1991 VL 224 BP 579 EP 599 DI 10.1017/S002211209100188X PG 21 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA FG991 UT WOS:A1991FG99100027 ER PT J AU GADELHAK, M BUSHNELL, DM AF GADELHAK, M BUSHNELL, DM TI SEPARATION CONTROL - REVIEW SO JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Review ID TURBULENT-BOUNDARY-LAYER; REYNOLDS-NUMBER AIRFOILS; WEIS-FOGH MECHANISM; UNSTEADY-FLOW; DRAG REDUCTION; SHOCK-WAVE; ACOUSTIC EXCITATION; DISCRETE VORTICES; LIFT GENERATION; FLUID-DYNAMICS AB Under certain conditions, wall-bounded flows separate. To improve the performance of natural or man-made flow systems, it may be beneficial to delay or advance this detachment process. The present article reviews the status and outlook of separation control for both steady and unsteady flows. Both passive and active techniques to prevent or to provoke flow detachment are considered and suggestions are made for further research. C1 UNIV NOTRE DAME,DEPT AEROSP & MECH ENGN,NOTRE DAME,IN 46556. NASA,LANGLEY RES CTR,DIV FLUID MECH,HAMPTON,VA 23665. OI Gad-el-Hak, Mohamed/0000-0001-6279-5118 NR 342 TC 107 Z9 112 U1 1 U2 20 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0098-2202 J9 J FLUID ENG-T ASME JI J. Fluids Eng.-Trans. ASME PD MAR PY 1991 VL 113 IS 1 BP 5 EP 30 DI 10.1115/1.2926497 PG 26 WC Engineering, Mechanical SC Engineering GA HP709 UT WOS:A1991HP70900002 ER PT J AU MAYNARD, NC AGGSON, TL BASINSKA, EM BURKE, WJ CRAVEN, P PETERSON, WK SUGIURA, M WEIMER, DR AF MAYNARD, NC AGGSON, TL BASINSKA, EM BURKE, WJ CRAVEN, P PETERSON, WK SUGIURA, M WEIMER, DR TI MAGNETOSPHERIC BOUNDARY DYNAMICS - DE-1 AND DE-2 OBSERVATIONS NEAR THE MAGNETOPAUSE AND CUSP SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FIELD-ALIGNED CURRENTS; INTERPLANETARY MAGNETIC-FIELD; CONVECTION ELECTRIC-FIELD; DEPENDENT PLASMA-FLOW; WIND ENERGY-TRANSFER; BIRKELAND CURRENTS; EARTHS MAGNETOPAUSE; DAYSIDE MAGNETOSPHERE; POLAR MAGNETOSPHERE; LAYER AB A broad spectrum of particle and field measurements was taken near local noon by the Dynamics Explorer satellites during the magnetic storm of September 6, 1982. While at apogee, DE 1 sampled the magnetospheric boundary layer at mid southern latitudes and, due to the passage of an intense solar wind burst, briefly penetrated into the magnetosheath. In the boundary layer and the adjacent magnetosheath the plasma flow was directed toward dawn. Variance and de Hoffmann-Teller analyses of electric and magnetic field data during the magnetopause crossing showed the magnetopause structure to be that of a rotational discontinuity or an intermediate shock with a substantial normal magnetic field component. This is consistent with an open magnetosphere model in which significant magnetic merging occurs at the local time of the spacecraft. The orbit of DE 2 carried it through the morning sector of the low-altitude, southern cusp. The measurements show a well-defined, cusp current system occurring on open magnetic field lines. At both cusp and subcusp latitudes the electric field was equatorward indicating a strongly eastward plasma flow. The boundary between these two regions was marked by the onset of magnetosheath precipitation and an electric field structure containing both poleward and equatorward spikes. The poleward spike has associated field-aligned currents which are closed by Pedersen currents and, from force balance considerations, is interpreted as the signature of a magnetic merging event at the magnetopause. The equatorward spike has the characteristics of a down-coming and reflected Alfven wave packet of finite dimensions. The high-altitude measurements suggest that the dayside boundary layer is made up of closed magnetic flux tubes, a large fraction of which drift to the magnetopause where merging with the IMF occurs. The merging line maps to the ionosphere as a "gap" across which the polar cap potential is applied to the magnetosphere. The potential is applied from a magnetosheath generator to the polar ionosphere by means of the cusp, field-aligned current system. The electric fields provide an ionospheric indicator of the mapping of the merging line location. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. REGIS COLL,WESTON,MA. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. LOCKHEED PALO ALTO RES LABS,DEPT 9120,PALO ALTO,CA 94304. TOKAI UNIV,INST RES & DEV,TOKYO 151,JAPAN. UNIV ALASKA,INST GEOPHYS,FAIRBANKS,AK 99775. RP MAYNARD, NC (reprint author), PHILLIPS LAB,DIV SPACE PHYS,OL AA,PL,PHG,BEDFORD,MA 01731, USA. RI Peterson, WK/A-8706-2009 OI Peterson, WK/0000-0002-1513-6096 NR 78 TC 47 Z9 47 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 MAR 1 PY 1991 VL 96 IS A3 BP 3505 EP 3522 DI 10.1029/90JA02167 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FA247 UT WOS:A1991FA24700009 ER PT J AU FUNG, SF HOFFMAN, RA AF FUNG, SF HOFFMAN, RA TI A SEARCH FOR PARALLEL ELECTRIC-FIELDS BY OBSERVING SECONDARY ELECTRONS AND PHOTOELECTRONS IN THE LOW-ALTITUDE AURORAL-ZONE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ATMOSPHERE EXPLORER-C; ENERGY-SPECTRA; POLAR-CAP; TO-FIELDS; AE-E; FLUXES; DISTRIBUTIONS; IONOSPHERE; ACCELERATION; DE-2 AB The high sensitivities of the auroral secondary electron and atmospheric photoelectron spectra (< 100 eV) to weak parallel dc electric fields make the particle distributions ideal for locating the lower boundary to the auroral electrostatic potential structures, which are often regarded as providing the mechanism responsible for the acceleration of auroral particles. The effects of weak parallel electric fields on the differential spectra of the low-energy electrons observed in inverted-V events are demonstrated with a set of heuristic model calculations. The spectral variations as a function of altitude of these electron populations in inverted-V events observed by the Dynamics Explorer 2 spacecraft are examined separately for events connected to dark and sunlit local atmospheres. By comparing the altitude dependence of the observed spectra with the model calculations, we show that there can be no more than a 2-volt potential drop on average between 400 and 900 km altitudes, corresponding to a distributed parallel dc electric field of less than 4 mu-V/m under the inverted-V electron precipitation regions. Isotropy of the photoelectrons in inverted-V events is also found to extend beyond the topside ionosphere, in accordance with the existence of a potential structure above the satellite. Statistical results on the spectral dependence of the secondary electrons on the inverted-V primary beam parameters are also presented. C1 ARC PROFESS SERV GRP INC,LANDOVER,MD. RP FUNG, SF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 696,GREENBELT,MD 20771, USA. RI Fung, Shing/F-5647-2012 NR 50 TC 12 Z9 12 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAR 1 PY 1991 VL 96 IS A3 BP 3533 EP 3548 DI 10.1029/90JA02244 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FA247 UT WOS:A1991FA24700011 ER PT J AU KLEIN, LW ROBERTS, DA GOLDSTEIN, ML AF KLEIN, LW ROBERTS, DA GOLDSTEIN, ML TI ANISOTROPY AND MINIMUM VARIANCE DIRECTIONS OF SOLAR-WIND FLUCTUATIONS IN THE OUTER HELIOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; ALFVENIC FLUCTUATIONS; WAVE REFRACTION; EVOLUTION; TURBULENCE; PIONEER-10; HELIOS-2; STREAMS; AU AB We systematically examine Voyager 2 magnetic field and plasma data over time intervals of 1 to 12 hours in the heliospheric range of 1 to 10 AU to study the evolution of the anisotropy of solar wind fluctuations. Consistent with previous results, we find that, on average, the directions of minimum variance vectors of magnetic fluctuations are close to the mean magnetic field direction with an increasing component of the variance along the field at larger scales. In both compression regions and rarefactions at large radial distances there is more spread in the minimum variance directions about the mean field than at smaller radial distances. The power in smaller-scale fluctuations in the magnetic field components perpendicular to the local mean field B0 is in the ratio of about 5:1 near 1 AU (compared to the power in fluctuations parallel to the field) at the scale of 1 hour but decreases to about 3:1 farther out. We find no evidence for selective enhancement of out-of-the-ecliptic components of fluctuations as predicted by a possible geometrical coupling between refracting Alfven waves and compressive modes. In contrast to results for field fluctuations, our analysis of fluctuations in the velocity shows that the minimum variance direction systematically remains more radially oriented and becomes increasingly less oriented along B0 with increasing heliocentric distance. The velocity fluctuations are also generally more isotropic than the magnetic fluctuations at all distances examined. Our observations cannot be explained by a superposed wave picture, and thus are consistent with the view that nonlinear turbulent evolution is responsible for the anisotropy in the fluctuations. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. RP KLEIN, LW (reprint author), APPL RES CORP,8201 CORP DR,LANDOVER,MD 20785, USA. RI Roberts, Dana/D-4625-2012; Goldstein, Melvyn/B-1724-2008 NR 39 TC 60 Z9 61 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 MAR 1 PY 1991 VL 96 IS A3 BP 3779 EP 3788 DI 10.1029/90JA02240 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FA247 UT WOS:A1991FA24700029 ER PT J AU BURLAGA, LF MCDONALD, FB NESS, NF LAZARUS, AJ AF BURLAGA, LF MCDONALD, FB NESS, NF LAZARUS, AJ TI COSMIC-RAY MODULATION - VOYAGER-2 OBSERVATIONS, 1987-1988 SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID MAGNETIC-FIELD; OUTER HELIOSPHERE; SOLAR MODULATION; CURRENT SHEET; FLOW SYSTEMS; PLASMA-FLOW; TRANSPORT; DRIFT; FLUCTUATIONS; PARTICLE AB We analyze the intensity profile of cosmic rays > 70 MeV observed by Voyager 2 and its relation to the interplanetary magnetic field and plasma at the beginning of the new modulation cycle from day 190, 1987 to day 345, 1988 in the region from 23.3 AU to 27.8 AU. The cosmic ray intensity profile was approximately a series of four plateaus separated by three steps in which the intensity dropped abruptly. Each step was associated with a region in which the magnetic field, density, and temperature were higher than average. The plateaus were associated with regions in which the magnetic field was alternately strong and weak. To first approximation, one can picture the solar wind within 200 AU during this interval as consisting of three shells between which the flow was quasi-periodic with a approximately 26 day periodicity. This picture is an oversimplification, since the large-scale magnetic field was approximately a multifractal. The latitudinal extent of the shells in the northern hemisphere was probably < 33-degrees, since no steps were observed by Voyager 1. Drift motions might play a role (1) during the recovery phase, just prior to the onset of the new modulation cycle, (2) in the plateau regions between the shells, (3) within the shells where drifts in various directions might mimic diffusion, and (4) close to 1 AU, where large regions of intense magnetic fields have not yet formed. However, the principal decreases in the cosmic ray intensity in the outer heliosphere during 1987 and 1988 were associated with the passage of broad regions of intense magnetic fields, consistent with the diffusion/convection model. C1 UNIV MARYLAND,INST PHYS SCI & TECHNOL,COLLEGE PK,MD 20740. UNIV DELAWARE,BAROL RES INST,NEWARK,DE 19716. MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. RP BURLAGA, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. NR 54 TC 44 Z9 44 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 MAR 1 PY 1991 VL 96 IS A3 BP 3789 EP 3799 DI 10.1029/90JA02245 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FA247 UT WOS:A1991FA24700030 ER PT J AU BIRN, J HONES, EW CRAVEN, JD FRANK, LA ELPHINSTONE, RD STERN, DP AF BIRN, J HONES, EW CRAVEN, JD FRANK, LA ELPHINSTONE, RD STERN, DP TI ON OPEN AND CLOSED FIELD LINE REGIONS IN TSYGANENKO FIELD MODEL AND THEIR POSSIBLE ASSOCIATIONS WITH HORSE COLLAR AURORAS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID PLANETARY MAGNETIC-FIELD; POLAR-CAP; GEOMAGNETIC-FIELD; CURRENT SYSTEM; ISEE-3; TAIL; PATTERN; TIMES; SHEET; ARCS AB Using the empirical Tsyganenko (1987) long model as a prime example of a magnetospheric field model, we have attempted to identify the boundary between open and closed field lines. We define as "closed" all field lines that are connected with the Earth at both ends and cross the equatorial plane earthward of x = -70R(E), the tailward validity limit of the Tsyganenko model. We find that the form of the open/closed boundary at the Earth's surface, identified with the polar cap boundary, can exhibit the arrowhead shape, pointed toward the Sun, observed in "horse collar auroras" (Hones et al., 1989). The "polar cap" size in the Tsyganenko model increases with increasing K(p) values, and it becomes rounder and less pointed. The superposition of a net B(y) field, which is the expected consequence of an IMF B(y), rotates the polar cap pattern and, for larger values, degrades the arrowhead shape, resulting in polar cap configurations consistent with known asymmetries in the aurora. The pointedness of the polar cap shape also diminishes or even completely disappears if the low-latitude magnetopause is assumed open and located considerably inside of the outermost magnetic flux surface in the Tsyganenko model. The arrowhead shape of the polar cap is found to be associated with a strong increase of B(z) from midnight toward the tail flanks, which is observed independently, and is possibly related to the NBZ field-aligned current system, observed during quiet times and strongly northward IMF B(z). The larger B(z) values near the flanks of the tail cause more magnetic flux to close through these regions than through the midnight equatorial region. Since field lines at the flanks primarily map to the dayside polar regions, it becomes plausible that the closed field line region extends to higher latitudes on the dayside than on the nightside, when the increase of B(z) becomes more pronounced. By comparison with a different field model we demonstrate that this association is not unique to the Tsyganenko model. The similarity of the quiet symmetric polar cap pattern to "horse collar" auroras suggests that the bright "bars," observed at the sides of the arrowhead shaped polar cap, are connected with the separatrix layers (or plasma sheet boundary layers) extending to the distant X line or separator, while the adjacent "web" regions, located between the bars and the main auroral oval, are connected with the low-latitude boundary regions along the flanks of the magnetotail. C1 UNIV IOWA,IOWA CITY,IA 52242. UNIV CALGARY,CALGARY T2N 1N4,ALBERTA,CANADA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BIRN, J (reprint author), UNIV CALIF LOS ALAMOS SCI LAB,LOS ALAMOS,NM 87545, USA. NR 28 TC 31 Z9 31 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 MAR 1 PY 1991 VL 96 IS A3 BP 3811 EP 3817 DI 10.1029/90JA02124 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FA247 UT WOS:A1991FA24700033 ER PT J AU VAUGHAN, RM BERGMANN, EV WALKER, BK AF VAUGHAN, RM BERGMANN, EV WALKER, BK TI COLLISION DETECTION FOR SPACECRAFT PROXIMITY OPERATIONS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB A new collision detection algorithm has been developed for use when two spacecraft are operating in the same vicinity. The two spacecraft are modeled as unions of convex polyhedra, where the resulting polyhedron may be either convex or nonconvex. The relative motion of the two spacecraft is assumed to be such that one vehicle is moving with constant linear and angular velocity with respect to the other. Contacts between the vertices, faces, and edges of the polyhedra representing the two spacecraft are shown to occur when the value of one or more of a set of functions is zero. The collision detection algorithm is then formulated as a search for the zeros (roots) of these functions. Special properties of the functions for the assumed relative trajectory are exploited to expedite the zero search. The new algorithm is the first algorithm that can solve the collision detection problem exactly for relative motion with constant angular velocity. This is a significant improvement over models of rotational motion used in previous collision detection algorithms. C1 CHARLES STARK DRAPER LAB INC,FLIGHT SYST,CAMBRIDGE,MA 02139. UNIV CINCINNATI,AEROSP ENGN & ENGN MECH,CINCINNATI,OH 45221. RP VAUGHAN, RM (reprint author), CALTECH,JET PROP LAB,TECH STAFF,NAVIGAT SYST SECT,PASADENA,CA 91109, USA. NR 7 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 MAR-APR PY 1991 VL 14 IS 2 BP 225 EP 229 DI 10.2514/3.20631 PG 5 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FD865 UT WOS:A1991FD86500001 ER PT J AU SPANOS, JT TSUHA, WS AF SPANOS, JT TSUHA, WS TI SELECTION OF COMPONENT MODES FOR FLEXIBLE MULTIBODY SIMULATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article ID ARTICULATED STRUCTURES; DYNAMIC ANALYSIS; MODAL SYNTHESIS; SYSTEMS; BODIES AB The assumed-modes method in multibody dynamics allows the elastic deformation of each component in the system to be approximated by a sum of products of spatial and temporal functions commonly known as modes and modal coordinates, respectively. This paper focuses on the choice of component modes used to model articulating and nonarticulating flexible multibody systems. Attention is directed toward three classical component mode synthesis methods whereby component normal modes are generated by treating the component interface as either fixed, free, or loaded with mass and stiffness contributions from the remaining components. The fixed and free interface normal modes are augmented by static shape functions termed constraint and residual modes, respectively. In this paper, a mode selection procedure is outlined whereby component modes are selected from the Craig-Bampton (fixed interface plus constraint), MacNeal-Rubin (free interface plus residual), or Benfield-Hruda (loaded interface) mode sets in accordance with a modal ordering scheme derived from balanced realization theory. The success of the approach is judged by comparing the actuator-to-sensor frequency response of the reduced-order system with that of the full-order system over the frequency range of interest. A finite element model of the Galileo spacecraft serves as an example in demonstrating the effectiveness of the proposed mode selection method. C1 CALTECH, JET PROP LAB, TECH STAFF, APPL TECHNOL SECT, PASADENA, CA 91109 USA. RP CALTECH, JET PROP LAB, TECH STAFF, GUIDANCE & CONTROL SECT, PASADENA, CA 91109 USA. NR 35 TC 27 Z9 29 U1 0 U2 2 PU AMER INST AERONAUTICS ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0731-5090 EI 1533-3884 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 1991 VL 14 IS 2 BP 278 EP 286 DI 10.2514/3.20638 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FD865 UT WOS:A1991FD86500008 ER PT J AU MERRILL, WC DELAAT, JC ABDELWAHAB, M AF MERRILL, WC DELAAT, JC ABDELWAHAB, M TI TURBOFAN ENGINE DEMONSTRATION OF SENSOR FAILURE-DETECTION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB In the paper, the results of a full-scale engine demonstration of a sensor failure detection algorithm are presented. The algorithm detects, isolates, and accommodates sensor failures using analytical redundancy. The experimental hardware, including the F100 engine, is described. Demonstration results were obtained over a large portion of a typical flight envelope for the F100 engine. They include both subsonic and supersonic conditions at both medium and full, nonafter burning, power. Estimated accuracy, minimum detectable levels of sensor failures, and failure accommodation performance for an F100 turbofan engine control system are discussed. C1 NASA,LEWIS RES CTR,ENGINE SYST BRANCH,CLEVELAND,OH 44135. RP MERRILL, WC (reprint author), NASA,LEWIS RES CTR,ADV CONTROLS TECHNOL BRANCH,CLEVELAND,OH 44135, USA. NR 12 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 1991 VL 14 IS 2 BP 337 EP 349 DI 10.2514/3.20645 PG 13 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FD865 UT WOS:A1991FD86500015 ER PT J AU MCENEANEY, WM AF MCENEANEY, WM TI OPTIMAL AEROASSISTED GUIDANCE USING LOH TERM APPROXIMATIONS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article; Proceedings Paper CT CONF ON GUIDANCE, NAVIGATION, AND CONTROL CY AUG 14-16, 1989 CL BOSTON, MA SP AMER INST AERONAUT & ASTRONAUT ID ORBITAL PLANE CHANGE AB This paper presents three guidance algorithms for aerocapture and/or aeroassisted orbital transfer with plane change. All three algorithms are based on the approximate solution of an optimal control problem at each guidance update. The chief assumptions is that Loh's term may be modeled as a function of the independent variable only. The first two algorithms maximize exit speed for fixed exit altitude, flight-path angle, and heading angle. The third minimizes, in one sense, the control effort for fixed exit altitude, flight-path angle, heading angle, and speed. Results are presented that indicate the near optimality of the solutions generated by the first two algorithms. Results are also presented that indicate the performance of the third algorithm in a simulation with unmodeled atmospheric density disturbances. C1 CALTECH,JET PROP LAB,TECH STAFF,NAVIGAT SYST SECT,PASADENA,CA 91109. NR 15 TC 4 Z9 4 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 1991 VL 14 IS 2 BP 368 EP 376 DI 10.2514/3.20648 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FD865 UT WOS:A1991FD86500018 ER PT J AU CURLEY, RD CHENG, VHL LIN, CA AF CURLEY, RD CHENG, VHL LIN, CA TI COVARIANCE ANALYSIS ALGORITHM FOR INTERCONNECTED SYSTEMS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB We present in this paper a covariance analysis algorithm for propagation of signal statistics in arbitrarily interconnected nonlinear hybrid systems, applied to six-degree-of-freedom systems specifically in our work. The algorithm uses statistical linearization theory to linearize the nonlinear subsystems, and the resulting linearized subsystems are considered in the original interconnection framework for propagation of the signal statistics. We shall refer to some nonlinearities commonly encountered in six-degree-of-freedom space-vehicle models to illustrate the limitations of this method, along with problems not encountered in standard deterministic simulation analysis. Moreover, we shall exhibit the performance of the algorithm numerically by comparing results from such techniques to results from Monte-Carlo analysis results, both applied to a simple two-dimensional space-intercept problem. C1 NASA,AMES RES CTR,AIRCRAFT GUIDANCE & NAVIGAT BRANCH,MOFFETT FIELD,CA 94035. NATL CHIAO TUNG UNIV,DEPT CONTROL ENGN,HSINCHU 30043,TAIWAN. RP CURLEY, RD (reprint author), INTEGRATED SYST INC,DIV ADV SYST,SANTA CLARA,CA 95054, 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 MAR-APR PY 1991 VL 14 IS 2 BP 425 EP 430 DI 10.2514/3.20655 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FD865 UT WOS:A1991FD86500025 ER PT J AU JOSHI, SM AF JOSHI, SM TI DESIGN OF OPTIMAL 2ND-ORDER STATE ESTIMATORS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note RP JOSHI, SM (reprint author), NASA,LANGLEY RES CTR,DIV GUIDANCE & CONTROL,HAMPTON,VA 23665, USA. NR 8 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 MAR-APR PY 1991 VL 14 IS 2 BP 466 EP 468 DI 10.2514/3.20661 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FD865 UT WOS:A1991FD86500031 ER PT J AU MARKLEY, FL JELETIC, JF AF MARKLEY, FL JELETIC, JF TI FAST ORBIT PROPAGATOR FOR GRAPHICAL DISPLAY SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Note C1 NASA,GODDARD SPACE FLIGHT CTR,ADV TECHNOL SECT,GREENBELT,MD 20771. RP MARKLEY, FL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CONTROL SYST SOFTWARE & SIMULAT SECT,GREENBELT,MD 20771, USA. NR 3 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 1991 VL 14 IS 2 BP 473 EP 475 DI 10.2514/3.20664 PG 3 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA FD865 UT WOS:A1991FD86500034 ER PT J AU RATHBUN, RE STEPHENS, DW TAI, DY AF RATHBUN, RE STEPHENS, DW TAI, DY TI FATE OF ACETONE IN AN OUTDOOR MODEL STREAM WITH A NITRATE SUPPLEMENT, SOUTHERN MISSISSIPPI, USA SO JOURNAL OF HYDROLOGY LA English DT Article AB The fate of acetone in an outdoor model stream to which nitrate was added as a nutrient supplement was determined. The stream, in southern Mississippi, U.S.A. was 234 m long. Water was supplied to the stream by an artesian well at about 1.21 s-1, resulting in a mean water velocity of about 0.5 m min-1. Acetone was injected continuously for 26 days resulting in concentrations of 20-40 mg l-1. A nitrate solution was injected for 21 days resulting in an instream concentration of about 1.7 mg l-1 at the upstream end of the stream. Rhodamine-WT dye was used to determine the travel time and dispersion characteristics of the stream, and t-butyl alcohol was used to determine the volatilization characteristics. Volatilization controlled the fate of acetone in the model stream. The lack of substantial bacterial degradation of acetone was contrary to expectations based on the results of laboratory degradation studies using model stream water enriched with nitrate. A possible explanation for the lack of significant degradation in the model stream may be the limited 6-h residence time of the acetone in the stream. C1 US GEOL SURVEY,SALT LAKE CITY,UT 84104. US GEOL SURVEY,STENNIS SPACE CTR,HYDROL INSTRUMENTAT FACIL,NSTL STN,MS 39529. RP RATHBUN, RE (reprint author), US GEOL SURVEY,5293 WARD RD,ARVADA,CO 80002, USA. NR 13 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-1694 J9 J HYDROL JI J. Hydrol. PD MAR PY 1991 VL 123 IS 3-4 BP 225 EP 242 DI 10.1016/0022-1694(91)90092-V PG 18 WC Engineering, Civil; Geosciences, Multidisciplinary; Water Resources SC Engineering; Geology; Water Resources GA FD572 UT WOS:A1991FD57200002 ER PT J AU DIPIETRO, MS KUMAR, KS WHITTENBERGER, JD AF DIPIETRO, MS KUMAR, KS WHITTENBERGER, JD TI COMPRESSION BEHAVIOR OF TIB2-PARTICULATE-REINFORCED COMPOSITES OF AL22FE3TI8 SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID DEFORMATION; ALLOYS AB The compression behavior of both the monolithic L1(2) compound Al22Fe3Ti8 and discontinuous composites obtained by incorporating approximately 1-mu-m TiB2 particles was studied for various volume percent reinforcements as a function of temperature and at high temperatures as a function of strain rate. In this study, by varying the Fe and Ti contents, the nature and volume fraction of the minor phases coexisting with the dominant L1(2) phase were changed and were examined with and without TiB2 reinforcement. At high strain rates (10(-4) s-1), the TiB2 reinforcements significantly enhance ambient and warm-temperature strength, although a crossover is observed at approximately 1000 K, above which the monolithic material is stronger than the composite. At slow strain rates (10(-7) s-1), representative of creep conditions, however, the TiB2-containing composites retain their superiority at least up to 1200 K. Power law fits of compressive flow stress at 1% strain versus strain rate yielded a stress exponent of approximately 3.0 with an activation energy of 310 kJ/mol for the monolithic material. For the particulate composites (20 vol. % TiB2), the corresponding values were approximately 5.0 and 465 kJ/mol, suggesting a change in the dominant deformation mechanism. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP DIPIETRO, MS (reprint author), MARTIN MARIETTA CORP LABS,BALTIMORE,MD 21227, USA. NR 16 TC 16 Z9 16 U1 1 U2 1 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 MAR PY 1991 VL 6 IS 3 BP 530 EP 538 DI 10.1557/JMR.1991.0530 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA FA769 UT WOS:A1991FA76900013 ER PT J AU HURWITZ, FI FARMER, SC TEREPKA, FM LEONHARDT, TA AF HURWITZ, FI FARMER, SC TEREPKA, FM LEONHARDT, TA TI SILSESQUIOXANE-DERIVED CERAMIC FIBERS SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID SILICON-CARBIDE FIBER; SIC FIBERS; STRUCTURAL CHARACTERIZATION; MECHANICAL-PROPERTIES; POLYMER PRECURSOR; NICALON; POLYCARBOSILANE; PYROLYSIS; STRENGTH AB Fibres formed from blends of silsesquioxane polymers were characterized to study the pyrolytic conversion of these precursors to ceramics. The morphology of fibres pyrolysed to 1400-degrees-C revealed primarily amorphous glasses whose conversion to beta-SiC is a function of both blend composition and pyrolysis conditions. Formation of beta-SiC crystallites within the glassy phase is favoured by higher than stoichiometric C/Si ratios, while carbothermal reduction of Si-O bonds to form SiC with loss of SiO and CO occurs at higher methyl/phenylpropyl silsesquioxane (lower C/Si) ratios. As the carbothermal reduction is assumed to be diffusion controlled, the fibres can serve as model systems to gain understanding of the silsesquioxane pyrolysis behaviour, and therefore are useful in the development of polysilsequioxane-derived ceramic matrices and coatings as well. C1 SVERDRUP TECHNOL INC,CLEVELAND,OH 44135. RP HURWITZ, FI (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 25 TC 24 Z9 24 U1 1 U2 6 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD MAR 1 PY 1991 VL 26 IS 5 BP 1247 EP 1252 DI 10.1007/BF00544462 PG 6 WC Materials Science, Multidisciplinary SC Materials Science GA FB093 UT WOS:A1991FB09300015 ER PT J AU SHAHIDSALESS, B AF SHAHIDSALESS, B TI PALATINI VARIATION OF CURVATURE-SQUARED ACTION AND GRAVITATIONAL COLLAPSE SO JOURNAL OF MATHEMATICAL PHYSICS LA English DT Article ID QUANTUM-GRAVITY; FORMALISM AB It is shown that Palatini variation of a class of gravitational actions based on a quadratic generalization of the Einstein-Hilbert action results in a metric-incompatible theory of gravity but one that satisfies Birkhoff's theorem. The usual fourth-order field equations are replaced by two second-order equations. Application of the field equations to a model of freely falling dust are discussed. RP SHAHIDSALESS, B (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 29 TC 10 Z9 10 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0022-2488 J9 J MATH PHYS JI J. Math. Phys. PD MAR PY 1991 VL 32 IS 3 BP 694 EP 697 DI 10.1063/1.529412 PG 4 WC Physics, Mathematical SC Physics GA EZ140 UT WOS:A1991EZ14000017 ER PT J AU DAVIS, S AF DAVIS, S TI UNSTEADY FACILITATED TRANSPORT OF OXYGEN IN HEMOGLOBIN-CONTAINING MEMBRANES AND RED-CELLS SO JOURNAL OF MEMBRANE SCIENCE LA English DT Article DE FACILITATED TRANSPORT; THEORY; ERYTHROCYTE MODEL; HEMOGLOBIN CONTAINING MEMBRANE ID DIFFUSION; MYOGLOBIN AB The unsteady transport of a reacting permeant diffusing through thin membranes and modeled red cells is investigated with a new nonlinear analysis of the reaction-diffusion equations. Implicit finite difference methods and a matrix formulation are used to study the deviation from equilibrium-based theories and the transient behavior of facilitated oxygen transport. The loading and unloading of oxygen from an erythrocyte model is computed and contrasted with the diffusion of oxygen across hemoglobin-saturated membranes. RP DAVIS, S (reprint author), NASA,AMES RES CTR,MS 260-1,MOFFETT FIELD,CA 94035, USA. NR 15 TC 4 Z9 4 U1 1 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0376-7388 J9 J MEMBRANE SCI JI J. Membr. Sci. PD MAR PY 1991 VL 56 IS 3 BP 341 EP 358 DI 10.1016/S0376-7388(00)83043-4 PG 18 WC Engineering, Chemical; Polymer Science SC Engineering; Polymer Science GA FD842 UT WOS:A1991FD84200008 ER PT J AU SPENCER, MN CHACKERIAN, C AF SPENCER, MN CHACKERIAN, C TI NITROGEN BROADENING OF OZONE NU-3 ROVIBRATIONAL TRANSITIONS AT 220-K SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID TEMPERATURE-DEPENDENCE; MU-M; AIR; COEFFICIENTS; PARAMETERS; HALFWIDTHS; LINE; LINEWIDTHS; REGION; O-3 RP SPENCER, MN (reprint author), NASA,AMES RES CTR,ATMOSPHER PHYS RES BRANCH,MOFFETT FIELD,CA 94035, USA. NR 18 TC 16 Z9 16 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 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD MAR PY 1991 VL 146 IS 1 BP 135 EP 142 DI 10.1016/0022-2852(91)90377-M PG 8 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA EZ162 UT WOS:A1991EZ16200011 ER PT J AU MOORE, NB HELLUMS, JW BECHTEL, T KITTREDGE, K CROSSFIELD, C AF MOORE, NB HELLUMS, JW BECHTEL, T KITTREDGE, K CROSSFIELD, C TI SEAL TESTING OF LARGE DIAMETER ROCKET MOTORS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB This investigative program examines leakage testing of elastomeric O-ring seals for a solid rocket casing and provides direction towards an improved nondestructive postassembly test. It also details test equipment for the Space Shuttle systems solid rocket boosters (SRB). The results are useful to designers of hardware for pressure containment vessels which use O-ring seals. However, testing of the SRB seal is complicated because the bore of the SRB cannot be pressurized to working pressure prior to launch; thus specialized seal test procedures are required. Using several subscale seal and groove configuration test fixtures equipped with either two or three O-ring seals in series, seal integrity is investigated with both a pressure decay and flowmeter methods. Both types of test equipment adequately detect the practical range of expected seal leak rates of 1 to 1 x 10(-4) sccs. The flow-meter leak test equipment appears to reduce testing time substantially. Limited seal leakage testing is performed on full-sized rocket motor segment seals, a pre-Challenger short stack, providing comparison of bore seals to test specimen bore and face seals. The conclusions are that seal reliability, verified via a performance pressure test, can be affected by temperature, quantity of grease, test pressure, and seal pressure load direction. Potential seal failure scenarios including contamination, seal damage, and sealing surface damage are discussed. Recommendations are made for an improved test procedure. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. TELEDYNE BROWN ENGN INC,HUNTSVILLE,AL 35807. RP MOORE, NB (reprint author), CAMERON OFFSHORE ENGN,HOUSTON,TX 77079, USA. NR 5 TC 0 Z9 0 U1 0 U2 5 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 MAR-APR PY 1991 VL 7 IS 2 BP 156 EP 162 DI 10.2514/3.23307 PG 7 WC Engineering, Aerospace SC Engineering GA FM898 UT WOS:A1991FM89800005 ER PT J AU MANZELLA, DH PENKO, PF DEWITT, KJ KEITH, TG AF MANZELLA, DH PENKO, PF DEWITT, KJ KEITH, TG TI TEST-CELL PRESSURE EFFECTS ON THE PERFORMANCE OF RESISTOJETS SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB The effect of test-cell pressure on the performance of two resistojets was investigated. Tests were conducted in a vacuum facility at pressures ranging from 4.3 x 10(-5) to 5.4 x 10-1 Torr for two resistojet configurations: a laboratory model and an engineering model for the Space Station. The tests showed that for each thruster there was a decline in performance, even after correcting for test-cell pressure, when tested in vacuum pressures above 10(-3) Torr. Measurements were made of surface temperature, thrust, and exit-plane pitot pressure over the range of test-cell pressures. From these measurements, the decline in performance of the laboratory-model resistojet at higher cell pressures was attributed to heat losses as a result of convection. For the engineering-model resistojet, the decline in performance was found to be a combination of heat loss and an effect of cell pressure on the nozzle flow. C1 NASA,CLEVELAND,OH 44135. UNIV TOLEDO,CHEM ENGN,TOLEDO,OH 43606. UNIV TOLEDO,MECH ENGN,TOLEDO,OH 43606. RP MANZELLA, DH (reprint author), SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 25 TC 2 Z9 2 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 1991 VL 7 IS 2 BP 269 EP 274 DI 10.2514/3.23320 PG 6 WC Engineering, Aerospace SC Engineering GA FM898 UT WOS:A1991FM89800018 ER PT J AU HSU, AT LIOU, MS AF HSU, AT LIOU, MS TI COMPUTATIONAL ANALYSIS OF UNDEREXPANDED JETS IN THE HYPERSONIC REGIME SO JOURNAL OF PROPULSION AND POWER LA English DT Note C1 NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,PROP AERODYNAM SECT,CLEVELAND,OH 44135. NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,COMPUTAT FLUID DYNAM BRANCH,CLEVELAND,OH 44135. RP HSU, AT (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,COMPUTAT PHYS SECT,CLEVELAND,OH 44135, USA. NR 12 TC 8 Z9 9 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 MAR-APR PY 1991 VL 7 IS 2 BP 297 EP 299 DI 10.2514/3.23324 PG 3 WC Engineering, Aerospace SC Engineering GA FM898 UT WOS:A1991FM89800022 ER PT J AU LANDIS, GA AF LANDIS, GA TI NEGATIVE MATTER PROPULSION - COMMENT SO JOURNAL OF PROPULSION AND POWER LA English DT Note RP LANDIS, GA (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135, USA. NR 6 TC 4 Z9 4 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 1991 VL 7 IS 2 BP 304 EP 304 DI 10.2514/3.23327 PG 1 WC Engineering, Aerospace SC Engineering GA FM898 UT WOS:A1991FM89800025 ER PT J AU NOCK, KT AF NOCK, KT TI GALILEO SPACECRAFT THERMAL DESIGNS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Editorial Material RP NOCK, KT (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1991 VL 28 IS 2 BP 129 EP 129 DI 10.2514/3.55625 PG 1 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200001 ER PT J AU REEVE, RT AF REEVE, RT TI THERMAL REDESIGN OF THE GALILEO SPACECRAFT FOR A VEEGA TRAJECTORY SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB In the aftermath of the Challenger tragedy, the May 1986 Shuttle/Centaur Launch of the Galileo spacecraft was postponed. The subsequent cancellation of the Centaur upper-stage program forced a redesign of the flight trajectory to Jupiter, from a direct trajectory, to a Venus-Earth-Earth Gravity Assist (VEEGA) trajectory on the lower energy two-stage Inertial Upper Stage (IUS). This trajectory would only be viable, however, if the spacecraft thermal design could be modified to withstand the nearly threefold increase in peak solar irradiance. A preliminary study indicated that the addition of sunshades and the generous exterior application of second-surface aluminized Kapton for reflecting high percentages of incident solar irradiation would be an adequate "hardening" of the spacecraft's pre-existing thermal protection system, provided that sun pointing at the relatively higher solar irradiance levels could be maintained. This article chronicles the general system-level thermal redesign effort from the start of a feasibility studies to its final implementation. It is the first of three articles about the thermal design of the Galileo spacecraft. RP REEVE, RT (reprint author), CALTECH,JET PROP LAB,SPACECRAFT THERMAL DESIGN GRP,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 3 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1991 VL 28 IS 2 BP 130 EP 138 DI 10.2514/3.26220 PG 9 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200002 ER PT J AU STULTZ, JW AF STULTZ, JW TI THERMAL DESIGN OF THE GALILEO SPUN AND DESPUN SCIENCE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Galileo spacecraft consists of an orbiter and probe that have instruments to investigate the chemical composition and physical state of Jupiter's atmosphere, the Jovian satellites, and the structure and physical dynamics of the Jovian magnetosphere. This article is the second of three about the thermal design of the Galileo spacecraft. Emphasis in the paper is on the thermal design of the spun and despun science. The thermal design of each instrument is unique and some employ radioisotope heater units. Cruise temperatures from the verification test in the Jet Propulsion Laboratory 25-ft simulator in August 1988 are presented. RP STULTZ, JW (reprint author), CALTECH,JET PROP LAB,SPACECRAFT THERMAL DESIGN GRP,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 5 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 MAR-APR PY 1991 VL 28 IS 2 BP 139 EP 145 DI 10.2514/3.26221 PG 7 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200003 ER PT J AU STULTZ, JW AF STULTZ, JW TI THERMAL DESIGN OF THE GALILEO BUS AND RETROPROPULSION MODULE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB This article is the third of three about the thermal design of the Galileo spacecraft (Casani, J. R., "Galileo's New Route to Jupiter," American Astronautical Society, Boulder, CO, Oct. 1986; and Reeve, R. T., "Thermal Redesign of the Galileo Spacecraft for a VEEGA Trajectory," AIAA Paper 89-1748, June 1989). Emphasis in this paper is on the thermal design of the Orbiter's bus and retropropulsion module central body, which houses the spun electronics and tankage, respectively. The thermal design of the central body is unique because it utilizes the internally mounted shunt radiator as the primary heat source. Cruise temperatures from the verification test in a space simulator in August 1988 are presented. Analytical results illustrating how the design responds during launch and in the event of an abort from orbit are discussed. RP STULTZ, JW (reprint author), CALTECH,JET PROP LAB,SPACECRAFT THERMAL DESIGN GRP,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 6 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 MAR-APR PY 1991 VL 28 IS 2 BP 146 EP 151 DI 10.2514/3.26222 PG 6 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200004 ER PT J AU VEMAGANTI, GR THORNTON, EA WIETING, AR AF VEMAGANTI, GR THORNTON, EA WIETING, AR TI STRUCTURED AND UNSTRUCTURED REMESHING METHOD FOR HIGH-SPEED FLOWS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID SCHEME AB An adaptive remeshing method using both triangular and quadrilateral elements suitable for high-speed flows is presented. For inviscid flows, the method generates completely unstructured meshes. For viscous flows, the boundary-layer edge is identified adaptively and a structured mesh is generated in the boundary layer; an unstructured mesh is generated in the inviscid region. Examples of inviscid and viscous mesh adaptations for high-speed flows are presented. A comparison is made between first-order and higher-order finite element algorithms when used in association with the remeshing method. C1 UNIV VIRGINIA, DEPT MECH & AEROSP ENGN, CHARLOTTESVILLE, VA 22901 USA. NASA, LYNDON B JOHNSON SPACE CTR, AEROTHERMAL LOADS BRANCH, HOUSTON, TX 77058 USA. RP LOCKHEED ENGN & SCI CO, HAMPTON, VA 23666 USA. NR 17 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUTICS ASTRONAUTICS PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0022-4650 EI 1533-6794 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1991 VL 28 IS 2 BP 158 EP 164 DI 10.2514/3.26224 PG 7 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200006 ER PT J AU GREENDYKE, RB HARTUNG, LC AF GREENDYKE, RB HARTUNG, LC TI APPROXIMATE METHOD FOR THE CALCULATION OF NONEQUILIBRIUM RADIATIVE HEAT-TRANSFER SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT 28TH AEROSPACE SCIENCE MEETING OF THE AMERICAN INST OF AERONAUTICS AND ASTRONAUTICS CY JAN 08-11, 1990 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB A simplified method for the calculation of radiative heat transfer in hypersonic re-entry flows where local thermal nonequilibrium (LTNE) conditions exist is presented. This method has been incorporated into the computer code RADMC (Radiation/Modified Corrections), which utilizes an approximate "two-state" model of the electronic levels of atoms and molecules in the determination of the populations of the excited states for both LTNE and local thermal equilibrium (LTE) conditions for each of the relevant chemical species. The population data are used to calculate a correction factor to the radiative cross sections in an eight-step nongray radiative heat transfer model. Uncoupled results have been obtained for various points along the proposed trajectory of the Aeroassist Flight Experiment and the Fire II trajectory, and compared with results obtained for the same flowfields from the Nonequil brium Air Radiation (NEQAIR) radiative heat-transfer code. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP GREENDYKE, RB (reprint author), ANALYT SERV & MAT INC,HAMPTON,VA 23666, USA. NR 12 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1991 VL 28 IS 2 BP 165 EP 171 DI 10.2514/3.26225 PG 7 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200007 ER PT J AU POWELL, RW NAFTEL, JC CRUZ, CI AF POWELL, RW NAFTEL, JC CRUZ, CI TI ASCENT PERFORMANCE ISSUES OF A VERTICAL-TAKEOFF ROCKET LAUNCH VEHICLE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Advanced manned launch systems studies under way at the NASA Langley Research Center are part of a broader effort that is examining options for the next manned space transportation system to be developed by the United States. One promising concept that uses near-term technologies is a fully reusable, two-stage vertical-takeoff rocket vehicle. This vehicle features parallel thrusting of the booster and orbiter with the booster cross-feeding the propellant to the orbiter until staging. In addition, after staging, the booster glides back unpowered to the launch site. This study concentrated on two issues that could affect the ascent performance of this vehicle. The first is the large gimbal angle range required for pitch trim until staging because of the propellant cross-feed. Results from this analysis show that if control is provided by gimballing of the rocket engines, they must gimbal greater than 20 deg, which is excessive when compared with current vehicles. However, this analysis also showed that this limit could be reduced to 10 deg if gimballing were augmented by throttling the booster engines. The second issue is the potential influence of off-nominal atmospheric conditions (density and winds) on the ascent performance. This study showed that a robust guidance algorithm could be developed that would insure accurate insertion, without prelaunch atmospheric knowledge. RP POWELL, RW (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,VEHICLE ANAL BRANCH,HAMPTON,VA 23665, USA. NR 9 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 MAR-APR PY 1991 VL 28 IS 2 BP 179 EP 183 DI 10.2514/3.26227 PG 5 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200009 ER PT J AU STANLEY, DO POWELL, RW AF STANLEY, DO POWELL, RW TI ABORT CAPABILITIES OF ROCKET-POWERED SINGLE-STAGE LAUNCH VEHICLES SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT 28TH AEROSPACE SCIENCE MEETING OF THE AMERICAN INST OF AERONAUTICS AND ASTRONAUTICS CY JAN 08-11, 1990 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB Application of advanced technologies to future launch vehicle designs would allow the introduction of a rocket-powered, single-stage-to-orbit (SSTO) launch system early in the next century. A fully reusable SSTO vehicle would be quite desirable from an operational standpoint; hence, this paper utilizes a vehicle design that incorporates the enabling technology advances in structure, propulsion, and subsystems that are essential. This paper examines the abort capabilities of an advanced SSTO launch vehicle that has five main engines. In the event of a single or dual main engine shutdown, it was determined when the vehicle could execute return-to-launch-site, abort-to-orbit, or down-range abort maneuvers. Throughout each abort maneuver, vehicle loads are kept within nominal ascent and entry design values. RP STANLEY, DO (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST,HAMPTON,VA 23665, USA. NR 5 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 MAR-APR PY 1991 VL 28 IS 2 BP 184 EP 191 DI 10.2514/3.26228 PG 8 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200010 ER PT J AU KARAKULKO, W FRAZIER, SR AF KARAKULKO, W FRAZIER, SR TI SHUTTLE EVOLUTION - IMPROVED AFT PROPULSION SYSTEM SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Several proposals for improving the Space Shuttle orbital maneuvering subsystem (OMS) have been proposed. One of the principal concepts is a pump-fed orbital maneuvering engine (OME). The higher performance of this engine reduces the propellant requirements or allows higher Shuttle altitudes. Another concept integrates the OMS and the aft reaction control subsystem (RCS). This reduces Orbiter weight, propellant residuals, and dispersions, and allows the RCS propellant to be loaded to meet specific mission requirements. This paper analyzes the performance improvements for a typical Space Shuttle manifest in the 1990s and Shuttle high-altitude delivery/reboost missions for several improved OMS configurations. A brief description of each proposed new OMS configuration is presented along with performance calculations for each. The utility of these performance changes varies, depending on the availability of the advanced solid rocket motor and the orbital maneuvering vehicle. The expected cost and implementation issues are addressed and compared, yielding a list of possible alternatives and their respective enhancement to the Shuttle capabilities. C1 MCDONNEL DOUGLAS SPACE SYST CO,WASHINGTON,DC 20024. RP KARAKULKO, W (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV PROP & POWER,HOUSTON,TX 77058, USA. NR 9 TC 0 Z9 0 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1991 VL 28 IS 2 BP 192 EP 196 DI 10.2514/3.26229 PG 5 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200011 ER PT J AU ZOLENSKY, M ATKINSON, D SEE, T ALLBROOKS, M SIMON, C FINCKENOR, M WARREN, J AF ZOLENSKY, M ATKINSON, D SEE, T ALLBROOKS, M SIMON, C FINCKENOR, M WARREN, J TI METEOROID AND ORBITAL DEBRIS RECORD OF THE LONG DURATION EXPOSURE FACILITY FRAME SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Long Duration Exposure Facility (LDEF) was recovered in January 1990, following 5.7 years of continuous exposure in low Earth orbit. The gravity-stabilized nature of LDEF permits the resolution of the flux and trajectories of impacting meteoroids and space-debris particulates. We have completed the collection of high-resolution stereoscopic video imaging of all impact features on the entire LDFE, and present here the preliminary results for the aluminum frame of the spacecraft. The raw data indicate possible extreme directionalities in impacting particulates for sizes greater than approximately 0.1 mm in diameter, which are not explained by current modeling. Following a Gaussian curve fit to the data, the leading-edge/trailing-edge ratio of large impact feature frequency observed for the LDEF is approximately 20.1, in good agreement with existing models (Zook, H. A., "Flux vs Direction of Impacts on LDEF by Meteoroids and Orbital Debris," Lunar and Planetary Science XXI, Lunar and Planetary Inst., Houston, TX, 1990, pp. 1385-1386). Finally, we present a list of recommendations for further LDEF analyses that will be necessary to ensure the safe design of spacecraft. C1 POD ASSOCIATES,ALBUQUERQUE,NM 87106. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. S CUBED INC,ALBUQUERQUE,NM 87106. WASHINGTON UNIV,MCDONNELL CTR SPACE SCI,ST LOUIS,MO 63130. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP ZOLENSKY, M (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH,SN2,HOUSTON,TX 77058, USA. NR 6 TC 1 Z9 3 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 MAR-APR PY 1991 VL 28 IS 2 BP 204 EP 209 DI 10.2514/3.26231 PG 6 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200013 ER PT J AU ARNOLD, WA JACQMIN, DA GAUG, RL CHAIT, A AF ARNOLD, WA JACQMIN, DA GAUG, RL CHAIT, A TI 3-DIMENSIONAL FLOW TRANSPORT MODES IN DIRECTIONAL SOLIDIFICATION DURING SPACE PROCESSING SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT 28TH AEROSPACE SCIENCE MEETING OF THE AMERICAN INST OF AERONAUTICS AND ASTRONAUTICS CY JAN 08-11, 1990 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT ID CRYSTAL-GROWTH AB A numerical model for the proposed GTE GaAs space experiment is presented. The model includes the actual ampule design and the experimentally obtained furnace thermal profiles. It is demonstrated that the commonly presumed axisymmetric flows in numerical studies are physically reasonable only when the local gravitational acceleration vector is parallel to the ampule's axis. Other gravitational orientations result in nontrivial three-dimensional flows that must be resolved using full three-dimensional models. Implications of the resulting flow and thermal fields on the growing crystal at conditions available during space processing are also discussed. RP ARNOLD, WA (reprint author), NASA,LEWIS RES CTR,MS 105-1,CLEVELAND,OH 44135, USA. NR 12 TC 16 Z9 16 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 MAR-APR PY 1991 VL 28 IS 2 BP 238 EP 243 DI 10.2514/3.26236 PG 6 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200018 ER PT J AU BUSH, HG HERSTROM, CL HEARD, WL COLLINS, TJ FICHTER, WB WALLSOM, RE PHELPS, JE AF BUSH, HG HERSTROM, CL HEARD, WL COLLINS, TJ FICHTER, WB WALLSOM, RE PHELPS, JE TI DESIGN AND FABRICATION OF AN ERECTABLE TRUSS FOR PRECISION SEGMENTED REFLECTOR APPLICATION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The design of a first generation, 4-m-diam, doubly curved, tetrahedral support truss for precision parabolic reflector panels, incorporating joints specifically designed for on-orbit astronaut assembly, is presented. Operational and design features of the erectable joint are detailed. Methods used to achieve very accurate strut lengths are described. Initial static and dynamic truss test results are presented that demonstrate linear structural response and predictability. Truss surface accuracy, determined photogrammetrically, is shown to be within 0.003 in. (rms) of design. C1 LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP BUSH, HG (reprint author), NASA,LANGLEY RES CTR,SPACECRAFT STRUCT BRANCH,MS 199,HAMPTON,VA 23665, USA. NR 11 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 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1991 VL 28 IS 2 BP 251 EP 257 DI 10.2514/3.26238 PG 7 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200020 ER PT J AU HARTWICH, PM HALL, RM HEMSCH, MJ AF HARTWICH, PM HALL, RM HEMSCH, MJ TI NAVIER-STOKES COMPUTATIONS OF VORTEX ASYMMETRIES CONTROLLED BY SMALL SURFACE IMPERFECTIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article; Proceedings Paper CT 28TH AEROSPACE SCIENCE MEETING OF THE AMERICAN INST OF AERONAUTICS AND ASTRONAUTICS CY JAN 08-11, 1990 CL RENO, NV SP AMER INST AERONAUT & ASTRONAUT AB Navier-Stokes analyses are employed to explore the driving mechanisms controlling asymmetric vortical flows with Re(D) = 0.8 x 10(6) (Reynolds number based on maximum diameter) over a 3.5-caliber tangent-ogive cylinder at large angles of attack (alpha = 20, 30, and 40 deg). All flowfield results are steady-state solutions to the three-dimensional, incompressible Navier-Stokes equations in the thin-layer approximation. The numerical results are in good agreement with experimental data. The major findings are 1) for alpha greater-than-or-equal-to 30 deg, the vortex flows are genuinely asymmetric yet recurrent; 2) asymmetric vortex patterns are sensitive towards such parameters as machine accuracy, grid topology, etc., unless they are triggered by a slight deformation (similar to an out-of-round nose tip) in the neighborhood of the apex; and 3) for alpha = 20 deg, the flow is symmetric for both circular and elliptic cross-sectional shapes of the nose tip. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. PRC KENTRON INC,DIV AEROSP TECHNOL,HAMPTON,VA 23666. RP HARTWICH, PM (reprint author), VIGYAN INC,HAMPTON,VA 23666, USA. NR 24 TC 8 Z9 8 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 MAR-APR PY 1991 VL 28 IS 2 BP 258 EP 264 DI 10.2514/3.26239 PG 7 WC Engineering, Aerospace SC Engineering GA FT142 UT WOS:A1991FT14200021 ER PT J AU HSIEH, C HENDRICKSON, J BAMFORD, R AF HSIEH, C HENDRICKSON, J BAMFORD, R TI DEVELOPMENT OF METHODOLOGY FOR QUALIFYING SAFETY CRITICAL A286 THREADED FASTENERS SO JOURNAL OF TESTING AND EVALUATION LA English DT Article DE THREADED FASTENERS; COLD ROLLED; A286 STAINLESS STEEL; PROOF TEST; FATIGUE LIFE; NONDESTRUCTIVE INSPECTION AB Nondestructive inspection and proof test are the principal flaw screening methods used to ensure the integrity of fracture critical fasteners. However, because of the limitations of various nondestructive inspection methods and the simplicity of the proof test, the latter method has been identified as a preferred method for flaw screening of fasteners. A test program was initiated at the Jet Propulsion Laboratory to experimentally determine the cyclic fatigue life of pre-cracked A286 stainless steel fasteners which just survived a proof test to a prescribed fraction of their ultimate tensile strength. The functional dependency of the cyclic fatigue life of a fastener on the fatigue stress (mean and alternating stresses), fastener size, material tensile strength, and proof load was formulated using the NASA/FLAGRO computer program. It was found that proof load has the strongest effect on fatigue life, while the mean stress has the least effect. The fastener size only has a minor effect, but the alternating stress range has a strong influence on the fatigue life of fasteners. Limited experimental verification of the hypothesized functional relationship is provided in this program for the effect of proof load and fastener size in addition to the analytic verification. RP HSIEH, C (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 11 TC 0 Z9 0 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 MAR PY 1991 VL 19 IS 2 BP 135 EP 148 PG 14 WC Materials Science, Characterization & Testing SC Materials Science GA FF346 UT WOS:A1991FF34600006 ER PT J AU CHIARAMONTE, FP ROSENTHAL, BN AF CHIARAMONTE, FP ROSENTHAL, BN TI WETTABILITY OF PYROLYTIC BORON-NITRIDE BY ALUMINUM SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article AB The wetting of pyrolytic boron nitride by molten 99.9999% pure aluminum was investigated by using the sessile drop method in a vacuum operating at approximately 660-mu-Pa at temperatures ranging from 700-degrees to 1000-degrees-C. The equilibrium contact angle decreased with an increase in temperature. For temperatures at 900-degrees-C or less the equilibrium contact angle was greater than 90-degrees. At 1000-degrees-C a nonwetting-towetting transition occurred and the contact angle stabilized at 49-degrees. RP CHIARAMONTE, FP (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 5 TC 13 Z9 13 U1 3 U2 3 PU AMER CERAMIC SOC PI WESTERVILLE PA 735 CERAMIC PLACE, PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD MAR PY 1991 VL 74 IS 3 BP 658 EP 661 DI 10.1111/j.1151-2916.1991.tb04077.x PG 4 WC Materials Science, Ceramics SC Materials Science GA FC009 UT WOS:A1991FC00900031 ER PT J AU NAKAJIMA, T KING, MD SPINHIRNE, JD RADKE, LF AF NAKAJIMA, T KING, MD SPINHIRNE, JD RADKE, LF TI DETERMINATION OF THE OPTICAL-THICKNESS AND EFFECTIVE PARTICLE RADIUS OF CLOUDS FROM REFLECTED SOLAR-RADIATION MEASUREMENTS .2. MARINE STRATOCUMULUS OBSERVATIONS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID AIRCRAFT OBSERVATIONS; LIQUID WATER; BOUNDARY-LAYER; PARAMETERIZATION; PROFILES; DROPLETS; SYSTEM; ALBEDO; OCEAN AB A multispectral scanning radiometer has been used to obtain measurements of the reflection function of marine stratocumulus clouds at 0.75, 1.65 and 2.16-mu-m. These observations were obtained from the NASA ER-2 aircraft as part of the First ISCCP [International Satellite Cloud Climatology Project] Regional Experiment (FIRE), conducted off the coast of southern California during July 1987. Multispectral images of the reflection function were used to derived the optical thickness and effective particle radius of stratiform cloud layers on four days. In addition to the radiation measurements, in situ microphysical measurements were obtained from the University of Washington Convair C-131A aircraft. In this paper we compare remote sensing results with in situ observations, which show a good spatial correlation for both optical thickness and effective radius. These comparisons further show systematic differences between remote sensing and in situ values, with a tendency for remote sensing to overestimate the effective radius by approximately 2-3-mu-m, independent of particle radius. The optical thickness, in contrast, is somewhat overestimated for small optical thicknesses and underestimated for large optical thicknesses. An introduction of enhanced gaseous absorption at a wavelength of 2.16-mu-m successfully explains some of these observed discrepancies. Marginal probability density functions of optical thickness, liquid water path and effective radius have been derived from our remote sensing results. The joint probability density function of liquid water path and effective radius shows that the effective radius increases as the liquid water path increases for optically thin clouds, in contrast to optically thick clouds for which the effective radius decreases with increasing liquid water path. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771. TOHOKU UNIV,FAC SCI,CTR ATMOSPHER & OCEAN VARIAT,SENDAI,MIYAGI 980,JAPAN. UNIV WASHINGTON,DEPT ATMOSPHER SCI,SEATTLE,WA 98195. RI King, Michael/C-7153-2011; Nakajima, Teruyuki/H-2370-2013 OI King, Michael/0000-0003-2645-7298; Nakajima, Teruyuki/0000-0002-9042-504X NR 48 TC 189 Z9 198 U1 3 U2 20 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 MAR 1 PY 1991 VL 48 IS 5 BP 728 EP 750 DI 10.1175/1520-0469(1991)048<0728:DOTOTA>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FC931 UT WOS:A1991FC93100005 ER PT J AU RATNAKUMAR, BV ATTIA, AI HALPERT, G AF RATNAKUMAR, BV ATTIA, AI HALPERT, G TI ALTERNATE CATHODES FOR SODIUM-METAL CHLORIDE BATTERIES SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Note RP RATNAKUMAR, BV (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 6 TC 10 Z9 10 U1 1 U2 4 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 MAR PY 1991 VL 138 IS 3 BP 883 EP 884 DI 10.1149/1.2085704 PG 2 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA FA236 UT WOS:A1991FA23600052 ER PT J AU MILAM, LJ AF MILAM, LJ TI TEST FACILITY REQUIREMENTS FOR THE THERMAL VACUUM THERMAL BALANCE TEST OF THE COSMIC BACKGROUND EXPLORER OBSERVATORY SO JOURNAL OF THE IES LA English DT Article DE COSMIC BACKGROUND EXPLORER; OBSERVATORY; COMPLEX FIXTURING; OBJECTIVES; CRYOPANEL; CONDENSIBLES AB The cosmic background explorer observatory (COBE) underwent a thermal vacuum/thermal balance (TV/TB) test in the space environment simulator (SES) at the Space Simulation Test Laboratory, Goddard Space Flight Cente. This was the largest and most complex test ever accomplished at this facility. The 4 x 4 m (13 x 13 ft) spacecraft weighed approximately 2223 kg (4900 lb) for the test. The test setup included simulator panels for the inboard solar array panels, simulator panels for the flight cowlings, sun and earth sensor stimuli, thermal/radio frequency shield heater stimuli, and a cryopanel for thermal control in the attitude control system/shunt dissipator area. The fixturing also included a 4.3 m (14 ft) diameter gaseous helium cryopanel which provided a 20-degrees Kelvin (K) (-253-degrees-C) environment for the calibration of one of the spacecraft's instruments, the differential microwave radiometer. This cryogenic panel caused extra contamination concerns so a special method was developed and written into the test procedure to prevent the high buildup of condensibles on the panel, which could have led to backstreaming of the thermal vacuum chamber. The test was completed successfully with a high-quality simulated space environment provided to the spacecraft. This paper describes the test requirements, test setup, special fixturing requirements, related contamination concerns, and a general discussion of the test and test results. RP MILAM, LJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 2 Z9 2 U1 1 U2 3 PU INST ENVIRONMENTAL SCI PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 SN 1052-2883 J9 J IES JI J. IES PD MAR-APR PY 1991 VL 34 IS 2 BP 27 EP 33 PG 7 WC Engineering, Environmental; Environmental Sciences; Instruments & Instrumentation SC Engineering; Environmental Sciences & Ecology; Instruments & Instrumentation GA FJ726 UT WOS:A1991FJ72600002 ER PT J AU BARNEY, RD AF BARNEY, RD TI CONTAMINATION CONTROL PROGRAM FOR THE COSMIC BACKGROUND EXPLORER - AN OVERVIEW SO JOURNAL OF THE IES LA English DT Article DE CONTAMINATION CONTROL; INFRARED INSTRUMENT CONTAMINATION; SPACECRAFT CONTAMINATION SPECIFICATIONS; PARTICULATE AND MOLECULAR CONTAMINATION; ENVIRONMENTALLY CONTROLLED SYSTEMS AB Each of the three state-of-the-art instruments flown aboard NASA's Cosmic Background Explorer (COBE)2 were designed, fabricated, and integrated using unique contamination control procedures to ensure accurate characterization of the diffuse radiation in the universe. The most stringent surface level cleanliness specifications ever attempted by NASA were required by the diffuse infrared background experiment (DIRBE) which is located inside a liquid helium cooled dewar along with the far infrared absolute spectrophotometer (FIRAS). The DIRBE instrument required complex stray radiation suppression that defined a cold primary optical baffle system surface cleanliness level of 100A.1,3 The cleanliness levels of the cryogenic instrument and the differential microwave radiometers (DMR) which were positioned symmetrically around the dewar were less stringent, ranging from level 300A to 500A. To achieve these instrument cleanliness levels, the entire flight spacecraft was maintained at level 500A throughout each phase of development. This paper describes the COBE contamination control program and the difficulties experienced in maintaining the cleanliness quality of personnel and flight hardware throughout instrument assembly, spacecraft integration, flight environmental qualification, and launch-site operations. RP BARNEY, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU INST ENVIRONMENTAL SCI PI MT PROSPECT PA 940 E NORTHWEST HIGHWAY, MT PROSPECT, IL 60056 SN 1052-2883 J9 J IES JI J. IES PD MAR-APR PY 1991 VL 34 IS 2 BP 34 EP 44 PG 11 WC Engineering, Environmental; Environmental Sciences; Instruments & Instrumentation SC Engineering; Environmental Sciences & Ecology; Instruments & Instrumentation GA FJ726 UT WOS:A1991FJ72600003 ER PT J AU FELDMAN, U EKBERG, JO SEELY, JF BROWN, CM KANIA, DR MACGOWAN, BJ KEANE, CJ BEHRING, WE AF FELDMAN, U EKBERG, JO SEELY, JF BROWN, CM KANIA, DR MACGOWAN, BJ KEANE, CJ BEHRING, WE TI TRANSITIONS OF THE TYPE 2S-2P IN HIGHLY CHARGED FLUORINE-LIKE AND OXYGEN-LIKE MO, CD, IN, AND SN SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS LA English DT Article ID = 2-2 TRANSITIONS; ENERGY-LEVELS; 2S22P5-2S2P6 TRANSITIONS; IONS; SPECTRA; WAVELENGTHS; PLASMAS; TOKAMAK; XXIV; XXV AB Transitions of the type 2s-2p in the F I and O I isoelectronic sequences have been identified in the extreme-ultraviolet spectra from plasmas that were produced by one beam of the Nova laser. In the F I sequence, two transitions were observed for the ions Mo33+, Cd39+, In40+, and Sn41+. In the O I sequence, 13 transitions were observed for Mo34+, 7 transitions for Cd40+, 8 transitions for In41+, and 7 transitions for Sn42+. The observed wavelengths were compared with calculated wavelengths, and predicted wavelengths are presented for the F I sequence up to atomic number Z = 64 and for the O I sequence to Z = 54. C1 UNIV CALIF LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,SOLAR PHYS BRANCH,GREENBELT,MD 20771. RP FELDMAN, U (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375, USA. NR 19 TC 12 Z9 12 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3224 J9 J OPT SOC AM B JI J. Opt. Soc. Am. B-Opt. Phys. PD MAR PY 1991 VL 8 IS 3 BP 531 EP 537 DI 10.1364/JOSAB.8.000531 PG 7 WC Optics SC Optics GA FA751 UT WOS:A1991FA75100006 ER PT J AU BELL, LD KAISER, WJ HECHT, MH DAVIS, LC AF BELL, LD KAISER, WJ HECHT, MH DAVIS, LC TI NEW ELECTRON AND HOLE SPECTROSCOPIES BASED ON BALLISTIC ELECTRON-EMISSION MICROSCOPY SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B LA English DT Article; Proceedings Paper CT 5TH INTERNATIONAL CONF ON SCANNING TUNNELING MICROSCOPY/SPECTROSCOPY ( STM 90 ) / 1ST INTERNATIONAL CONF ON NANOMETER SCALE SCIENCE AND TECHNOLOGY ( NANO 1 ) CY JUL 23-27, 1990 CL BALTIMORE, MD SP AMER VACUUM SOC, USN, OFF NAVAL RES, USAF, OFF SCI RES, NATL SCI FDN, JOHN HOPKINS UNIV, APPL PHYS LAB AB Ballistic electron emission microscopy (BEEM) is shown to be one of a class of carrier transport nanospectroscopies which measure both elastic and inelastic transport of electrons and holes in thin film structures. In BEEM, electrons are injected into a metal film from a tunnel tip and are collected in the substrate after ballistic transport through the film. An analogous spectroscopy can be performed using hole transport into a p-type semiconductor substrate. In the present work, it is shown that inelastic scattering in metal films results in electron-hole pair creation which can be detected by similar techniques. A theory for this spectroscopy successfully explains the experimental results. C1 FORD MOTOR CO,RES STAFF,DEARBORN,MI 48121. RP BELL, LD (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 13 TC 26 Z9 26 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1071-1023 J9 J VAC SCI TECHNOL B JI J. Vac. Sci. Technol. B PD MAR-APR PY 1991 VL 9 IS 2 BP 594 EP 600 DI 10.1116/1.585466 PN 2 PG 7 WC Engineering, Electrical & Electronic; Nanoscience & Nanotechnology; Physics, Applied SC Engineering; Science & Technology - Other Topics; Physics GA FL004 UT WOS:A1991FL00400040 ER PT J AU ALLEN, RG GICHUKI, FN ROSENZWEIG, C AF ALLEN, RG GICHUKI, FN ROSENZWEIG, C TI CO2-INDUCED CLIMATIC CHANGES AND IRRIGATION-WATER REQUIREMENTS SO JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT-ASCE LA English DT Article ID CROP COEFFICIENTS; CO2 CONCENTRATION; ATMOSPHERIC CO2; EVAPOTRANSPIRATION; TRANSPIRATION; INCREASE; MODEL AB Effects of CO2-induced climatic changes on irrigation-water requirements (IR) in the Great Plains region were evaluated using results of global atmospheric-circulation models with a water balance-IR model. Increases were predicted for evapotranspiration E(t) due to predicted increases in air temperature, solar radiation, and wind speed under doubled concentrations of atmospheric carbon dioxide (2 x CO2). Predicted increases in humidity under the 2 x CO2 scenarios and shifting of crop life cycles to months with lower levels of solar radiation moderated predicted increases in E(t). Increases in irrigation requirements were caused primarily by increases in evaporative demands and changes in precipitation patterns. Increases in net seasonal IR for alfalfa were larger due to predicted increases in length of frost-free growing seasons and higher evaporative demands as compared to winter wheat and corn. Decreases or only modest increases in seasonal irrigation requirements were projected under 2 x CO2 scenarios for corn and winter wheat due to reductions in length of crop life cycles and projected increases in bulk stomatal resistances. C1 NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025. UNIV NAIROBI,DEPT AGR ENGN,NAIROBI,KENYA. COLUMBIA UNIV,NEW YORK,NY 10027. RP ALLEN, RG (reprint author), UTAH STATE UNIV,DEPT AGR & IRRIGAT ENGN,LOGAN,UT 84322, USA. NR 35 TC 22 Z9 22 U1 0 U2 3 PU ASCE-AMER SOC CIVIL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0733-9496 J9 J WATER RES PL-ASCE JI J. Water Resour. Plan. Manage.-ASCE PD MAR-APR PY 1991 VL 117 IS 2 BP 157 EP 178 DI 10.1061/(ASCE)0733-9496(1991)117:2(157) PG 22 WC Engineering, Civil; Water Resources SC Engineering; Water Resources GA EY969 UT WOS:A1991EY96900001 ER PT J AU MCCORMICK, MP WINKER, DM AF MCCORMICK, MP WINKER, DM TI DIAL, RAMAN, SOLID-STATE LIDARS ADVANCE SO LASER FOCUS WORLD LA English DT Review RP MCCORMICK, MP (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PENNWELL PUBL CO PI NASHUA PA 5TH FLOOR TEN TARA BOULEVARD, NASHUA, NH 03062-2801 SN 0740-2511 J9 LASER FOCUS WORLD JI Laser Focus World PD MAR PY 1991 VL 27 IS 3 BP 38 EP & PG 0 WC Optics SC Optics GA FB022 UT WOS:A1991FB02200011 ER PT J AU LAIRD, P GAMBLE, E AF LAIRD, P GAMBLE, E TI A PAC ALGORITHM FOR MAKING FEATURE MAPS SO MACHINE LEARNING LA English DT Article DE TOPOLOGICAL FEATURE-MAP; PAC-LEARNING; PROBABILITY DISTRIBUTION AB Kohonen and others have devised network algorithms for computing so-called topological feature maps. We describe a new algorithm, called the CDF-Inversion (CDFI) Algorithm, that can be used to learn feature maps and, in the process, approximate an unknown probability distribution to within any specified accuracy. The primary advantages of the algorithm over previous feature-map algorithms are that it is simple enough to analyze mathematically for correctness and efficiency, and that it distributes the points of the map evenly, in a sense that can be made rigorous. Like other vector-quantization algorithms it is potentially useful for many applications, including monitoring and statistical modeling. While not a network algorithm, the CDFI algorithm is well-suited to implementation on parallel computers. C1 STERLING FED SYST INC,PALO ALTO,CA. RP LAIRD, P (reprint author), NASA,AMES RES CTR,MAIL STOP 24417,MOFFETT FIELD,CA 94035, USA. NR 15 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 0885-6125 J9 MACH LEARN JI Mach. Learn. PD MAR PY 1991 VL 6 IS 2 BP 145 EP 160 PG 16 WC Computer Science, Artificial Intelligence SC Computer Science GA FA897 UT WOS:A1991FA89700002 ER PT J AU MISRA, AK AF MISRA, AK TI REACTION OF TI AND TI-AL ALLOYS WITH ALUMINA SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID COMPOSITES AB The reaction of single-crystal Al2O3 with pure Ti and Ti-Al alloys with different Al concentrations was examined in the temperature range of 1173 to 1573 K. Significant reaction occurred between Al2O3 and the Ti-Al alloys with Al concentrations lower than that corresponding to the gamma-TiAl phase. The reaction mechanism was determined to be simultaneous diffusion of Al and atomic oxygen from Al2O3 into Ti and the Ti-Al alloys. RP MISRA, AK (reprint author), SVERDRUP TECHNOL INC,NASA,LEWIS RES CTR GRP,CLEVELAND,OH 44135, USA. NR 10 TC 49 Z9 53 U1 1 U2 4 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD MAR PY 1991 VL 22 IS 3 BP 715 EP 721 DI 10.1007/BF02670294 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA EZ837 UT WOS:A1991EZ83700015 ER PT J AU SMIALEK, JL AF SMIALEK, JL TI EFFECT OF SULFUR REMOVAL ON AL2O3 SCALE ADHESION SO METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID NICRAL ALLOYS; REACTIVE ELEMENTS; MCRALY ALLOYS; ADHERENCE; SURFACE; SEGREGATION; OXIDATION; NICKEL; DISPERSIONS; ADDITIONS AB If the role of reactive element dopants in producing Al2O3 scale adhesion on NiCrAl alloys is to getter sulfur and prevent interfacial segregation, then eliminating sulfur from undoped alloys should also produce adherence. Four experiments successfully produced scale adhesion by sulfur removal alone. (1) Repeated oxidation and polishing of a pure NiCrAl alloy lowered the sulfur content from 10 to 2 parts per million by weight (ppmw), presumably by removing the segregated interfacial layer after each cycle. Total scale spallation changed to total retention after 13 such cycles, with no changes in the scale or interfacial morphology. (2) Thinner samples became adherent after fewer oxidation polishing cycles because of a more limited supply of sulfur. (3) Spalling in subsequent cyclic oxidation tests of samples from experiment (1) was a direct function of the initial sulfur content. (4) Desulfurization to 0.1 ppmw levels was accomplished by annealing melt-spun foil in 1 atm H-2. These foils produced oxidation weight change curves for 500 1-hour cycles at 1100-degrees-C similar to those for Y- or Zr-doped NiCrAl. The transition between adherent and nonadherent behavior was modeled in terms of sulfur flux, sulfur content, and sulfur segregation. RP SMIALEK, JL (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 37 TC 127 Z9 131 U1 2 U2 16 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0360-2133 J9 METALL TRANS A PD MAR PY 1991 VL 22 IS 3 BP 739 EP 752 DI 10.1007/BF02670297 PG 14 WC Materials Science, Multidisciplinary SC Materials Science GA EZ837 UT WOS:A1991EZ83700018 ER PT J AU OWEN, FN WHITE, RA AF OWEN, FN WHITE, RA TI SURFACE PHOTOMETRY OF RADIO GALAXIES .2. CLUSTER SOURCES SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article ID VLA OBSERVATIONS; INTERFEROMETER OBSERVATIONS; ELLIPTICAL GALAXIES; ABELL CLUSTERS; TAILS; JET AB CCD surface photometry of 52 radio galaxies in the R-band is reported. The project was designed to study the parent galaxies of radio sources in rich clusters of galaxies and to compare the results with our earlier study of FR I and FR II sources. A radio versus optical luminosity plot shows the same division between FR I and FR II radio sources much more clearly because of the larger sample. A good correlation between radio and optical luminosity is evident for the FR I sources alone but, as reported earlier, FR II sources do not fit this correlation. The results from the larger data set suggest that the FR I/FR II break may be a function of both radio and optical luminosity. The parent galaxies of all the radio sources studied seem to form a one-parameter family with no differences in galaxies inside and outside clusters except that optically brighter galaxies seem to occur more often in rich clusters. The fainter optical galaxies near L* fit r1/4 laws well, while more luminous galaxies deviate toward D-like structures. This change in structure seems to be smoothly correlated with increasing luminosity. There is also a trend for the more luminous galaxies to be more elongated. Classical Double sources in our sample are associated with the lowest optical luminosities near L*. Narrow Angle Tail sources and Twin Jets are associated with intermediate optical luminosities, while the most radio-loud Twin Jet sources are found in the most luminous optical galaxies. More distorted sources such as Narrow Angle Tail sources and Bent Twin Jets or Wide Angle Tail sources clearly occur more often in rich clusters; however, they seem to fit into the correlation between radio and optical luminosity independent of their structure. C1 NASA,GODDARD SPACE FLIGHT CTR,DIV SPACE DATA & COMP,GREENBELT,MD 20771. RP OWEN, FN (reprint author), NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801, USA. NR 52 TC 81 Z9 81 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 MAR 1 PY 1991 VL 249 IS 1 BP 164 EP 171 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FA997 UT WOS:A1991FA99700018 ER PT J AU SINGH, JJ EFTEKHARI, A STCLAIR, TL AF SINGH, JJ EFTEKHARI, A STCLAIR, TL TI LOW-ENERGY POSITRON FLUX GENERATOR FOR LIFETIME STUDIES IN THIN-FILMS SO NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS LA English DT Article ID SPECTRA AB A slow positron flux generator using well-annealed polycrystalline tungsten moderators and a Na-22 positron source has been developed for lifetime studies in thin polymer films. A 250-mu-C source, deposited on a 2.54-mu-m thick aluminized mylar film, is sandwiched between two 0.0127 cm thick 2.54 x 2.54 cm tungsten strips. Two 2.54 cm x 2.54 cm test polymer films, whose thickness ranges from 0.00127 to 0.0127 cm, insulate the two tungsten moderator strips from the aluminized mylar source holder. A potential difference of 10-100 V, depending on the test polymer film thickness, is applied between the tungsten strips and the source holder. Thermalized positrons diffusing out of the moderator strips are attracted to the source holder when it is at a negative potential. These positrons have to drift through the test polymer films in order to reach the source holder. On the other hand, they are prevented from entering the test polymer films when the source holder is at a positive potential. The difference between the positron lifetime spectrum with the source at +/- V V is strongly related to the test film spectrum. Thus the new generator becomes an effective source of positrons for assaying thin polymer films for their molecular morphology. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23665. RP SINGH, JJ (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 12 TC 6 Z9 6 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0168-583X J9 NUCL INSTRUM METH B JI Nucl. Instrum. Methods Phys. Res. Sect. B-Beam Interact. Mater. Atoms PD MAR PY 1991 VL 53 IS 3 BP 342 EP 348 DI 10.1016/0168-583X(91)95624-M PG 7 WC Instruments & Instrumentation; Nuclear Science & Technology; Physics, Atomic, Molecular & Chemical; Physics, Nuclear SC Instruments & Instrumentation; Nuclear Science & Technology; Physics GA FE939 UT WOS:A1991FE93900016 ER PT J AU NUSSENZVEIG, HM WISCOMBE, WJ AF NUSSENZVEIG, HM WISCOMBE, WJ TI COMPLEX ANGULAR-MOMENTUM APPROXIMATION TO HARD-CORE SCATTERING SO PHYSICAL REVIEW A LA English DT Article ID SPHERES AB The complex angular momentum (CAM) approximation for nonrelativistic quantum scattering by a hard sphere-a union of the recently developed CAM uniform approximation with a semiclassical WKB-like approximation valid at large angles-is shown to be remarkably accurate over the complete range of scattering angles, and down to size parameters (circumference to de Broglie wave-length ratios) of order unity. The best approximations previously derivable (Fock-type) cannot reach large scattering angles where semiclassical approximations are useful; even at angles where Fock-type approximations are valid, they are typically two or more orders of magnitude less accurate than CAM. The crucial new feature responsible for the high accuracy of the CAM approximation is the treatment of large-angle diffraction associated with (a) tunneling near the edge of the scatterer, and (b) anomalous reflection. C1 PONTIFICA UNIV CATOLICA,DEPT FIS,BR-22452 RIO DE JANEIRO,BRAZIL. RP NUSSENZVEIG, HM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 913,GREENBELT,MD 20771, USA. RI Wiscombe, Warren/D-4665-2012 OI Wiscombe, Warren/0000-0001-6844-9849 NR 25 TC 21 Z9 21 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD MAR 1 PY 1991 VL 43 IS 5 BP 2093 EP 2112 DI 10.1103/PhysRevA.43.2093 PG 20 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA EZ702 UT WOS:A1991EZ70200001 ER PT J AU EBY, PB AF EBY, PB TI CROSS-SECTION FOR PRODUCTION OF LOW-ENERGY ELECTRON-POSITRON PAIRS BY RELATIVISTIC HEAVY-IONS SO PHYSICAL REVIEW A LA English DT Article ID E+E PAIRS; COLLISIONS; SPECTRUM; MUONS; ATOMS AB Starting with the lowest-order unscreened QED matrix element for electron-positron pair production by heavy charged particles, we calculate the cross section for this process differential in all independent variables and valid for all pair energies small compared to the incident particle energy. Plane-wave solutions to the Dirac equation are used to represent the electron and positron in this calculation. The gauge-invariance condition is used throughout the calculation to separate the cross section into quantities that reduce to the Weizsacker-Williams result in the appropriate limit and other terms that are not included in the Weizsacker-Williams approximation. The accuracy of the Weizsacker-Williams method, on which previous calculations of higher-order corrections were based, can thereby be estimated. Integration over the possible emission angles of one of the pair members gives an expression valid for low-energy pairs that can be compared with previous work based on the Weizsacker-Williams method. Integration over the possible angles of the other pair member then gives an expression that turns out to be identical to one derived by Racah, as we show in detail, although some of the expressions given here prior to the second angular integration have not been given previously. The high energy-transfer limit of the expression for the cross section integrated over electron and position angles is shown to be identical to that of Kelner in the unscreened case. Additional numerical integrations over the remaining variables are performed for a range of projectile energies using Kelner's treatment of screening. These examples allow the determination of the accuracy of the Weizsacker-Williams method as previously applied as a function of projectile and pair energy. The results for the total cross section, which include the correct behavior for low energy transfers, are compared with previous calculations. RP EBY, PB (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 17 TC 14 Z9 14 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD MAR 1 PY 1991 VL 43 IS 5 BP 2258 EP 2269 DI 10.1103/PhysRevA.43.2258 PG 12 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA EZ702 UT WOS:A1991EZ70200015 ER PT J AU DOSCHEK, GA FELDMAN, U BHATIA, AK AF DOSCHEK, GA FELDMAN, U BHATIA, AK TI INTENSITIES OF THE NEONLIKE IRON (FE-16+) 2P53S-2P53P AND 2P53P-2P53D TRANSITIONS IN SOLAR-FLARE SPECTRA SO PHYSICAL REVIEW A LA English DT Note ID COLLISION CROSS-SECTIONS; FE-XVII; ISOELECTRONIC SEQUENCE; LINE RATIOS; EXCITATION; IONS; IDENTIFICATIONS; COEFFICIENTS; STRENGTHS AB We present relative spectral line intensities for 16 3s-3p and 3p-3d transitions in the neonlike ion Fe16+, obtained from solar-flare spectra. The spectra were obtained by a Naval Research Laboratory slitless spectrograph flown on the Skylab manned space station. The results are of relevance to x-ray-laser experiments involving collisional pumping of excited states of neonlike ions, and to the analysis of solar-flare spectra. The relative line intensities are measured to an accuracy of about 30%. The measured line intensities are compared with theoretical line intensities calculated assuming electron collisional excitation within the Fe16+ ion followed by deexcitation and radiative decay. The measured and theoretical intensities agree to within less than a factor of 2 for all but one line. The important J = 0 lines (3p 1S0-3s 1P1,3s 3P1) at 254.87 and 204.65 angstrom are about a factor of 1.4 weaker than predicted, which is almost within experimental error. The 3s 3P2-3p 3S1 line at 409.69 angstrom is 2.3 times weaker than predicted, and this is unexplained. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP DOSCHEK, GA (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375, USA. NR 21 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 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD MAR 1 PY 1991 VL 43 IS 5 BP 2565 EP 2568 DI 10.1103/PhysRevA.43.2565 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA EZ702 UT WOS:A1991EZ70200054 ER PT J AU KHAN, F KHANDELWAL, GS TOWNSEND, LW WILSON, JW NORBURY, JW AF KHAN, F KHANDELWAL, GS TOWNSEND, LW WILSON, JW NORBURY, JW TI OPTICAL-MODEL DESCRIPTION OF MOMENTUM-TRANSFER IN RELATIVISTIC HEAVY-ION COLLISIONS SO PHYSICAL REVIEW C LA English DT Article ID NUCLEUS-NUCLEUS COLLISIONS; ABRASION-ABLATION; FRAGMENTATION; PROJECTILES; ENERGIES AB An optical model description of momentum transfer in relativistic heavy ion collisions, based upon composite particle multiple-scattering theory, is presented. The imaginary component of the complex momentum transfer, which comes from the absorptive part of the optical potential, is shown to be the main contributor to the momentum loss of the projectile. Within the context of the Goldhaber formalism, predictions of fragment momentum distribution observables are made and compared with experimental data. Use of the model as a tool for estimating collision impact parameters is also discussed. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RIDER COLL,DEPT PHYS,LAWRENCEVILLE,NJ 08648. RP KHAN, F (reprint author), OLD DOMINION UNIV,DEPT PHYS,NORFOLK,VA 23529, USA. FU NCPDCID CDC HHS [NCCI-42] NR 29 TC 10 Z9 10 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 MAR PY 1991 VL 43 IS 3 BP 1372 EP 1377 DI 10.1103/PhysRevC.43.1372 PG 6 WC Physics, Nuclear SC Physics GA FA990 UT WOS:A1991FA99000050 PM 9967177 ER PT J AU MAUNG, KM GROSS, F TJON, JA TOWNSEND, LW WALLACE, SJ AF MAUNG, KM GROSS, F TJON, JA TOWNSEND, LW WALLACE, SJ TI RELATIVISTIC PROTON-NUCLEUS SCATTERING AND ONE-BOSON-EXCHANGE MODELS SO PHYSICAL REVIEW C LA English DT Article ID IMPULSE APPROXIMATION; ELASTIC-SCATTERING; EQUATION; PB-208; CA-40; O-16 AB Relativistic p-Ca-40 elastic scattering observables are calculated using four sets of relativistic NN amplitudes obtained from different one-boson-exchange (OBE) models. The first two sets are based upon a relativistic equation in which one particle is on mass shell and the other two sets are obtained from a quasipotential reduction of the Bethe-Salpeter equation. Results at 200, 300, and 500 MeV are presented for these amplitudes. Differences between the predictions of these models provide a study of the uncertainty in constructing Dirac optical potentials from OBE-based NN amplitudes. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. COLL WILLIAM & MARY,DEPT PHYS,WILLIAMSBURG,VA 23185. CONTINUOUS ELECTRON BEAM ACCELERATOR FACIL,NEWPORT NEWS,VA 23606. STATE UNIV UTRECHT,INST THEORET PHYS,3508 TA UTRECHT,NETHERLANDS. UNIV MARYLAND,DEPT PHYS & ASTRON,COLLEGE PK,MD 20742. RP MAUNG, KM (reprint author), HAMPTON UNIV,DEPT PHYS,HAMPTON,VA 23668, USA. NR 26 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 MAR PY 1991 VL 43 IS 3 BP 1378 EP 1388 DI 10.1103/PhysRevC.43.1378 PG 11 WC Physics, Nuclear SC Physics GA FA990 UT WOS:A1991FA99000051 ER PT J AU RUBINSTEIN, R BARTON, JM AF RUBINSTEIN, R BARTON, JM TI RENORMALIZATION-GROUP ANALYSIS OF ANISOTROPIC DIFFUSION IN TURBULENT SHEAR FLOWS SO PHYSICS OF FLUIDS A-FLUID DYNAMICS LA English DT Article ID STATISTICAL-ANALYSIS; SCALAR DIFFUSION; PASSIVE-SCALAR AB The renormalization group is applied to compute anisotropic corrections to the scalar eddy diffusivity representation of turbulent diffusion of a passive scalar. The corrections are linear in the mean velocity gradients. All model constants are computed theoretically. A form of the theory valid at arbitrary Reynolds number is derived. The theory applies only when convection of the velocity-scalar correlation can be neglected. A ratio of diffusivity components, found experimentally to have a nearly constant value in a variety of shear flows, is computed theoretically for flows in a certain state of equilibrium. The theoretical value is well within the fairly narrow range of experimentally observed values. Theoretical predictions of this diffusivity ratio are also compared with data from experiments and direct numerical simulations of homogeneous shear flows with constant velocity and scalar gradients. RP RUBINSTEIN, R (reprint author), NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,DEPT AEROMECH,CLEVELAND,OH 44135, USA. NR 20 TC 20 Z9 20 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0899-8213 J9 PHYS FLUIDS A-FLUID PD MAR PY 1991 VL 3 IS 3 BP 415 EP 421 DI 10.1063/1.858097 PG 7 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA EZ697 UT WOS:A1991EZ69700007 ER PT J AU STAINES, K BALOGH, A COWLEY, SWH HYNDS, RJ YATES, TS RICHARDSON, IG SANDERSON, TR WENZEL, KP MCCOMAS, DJ TSURUTANI, BT AF STAINES, K BALOGH, A COWLEY, SWH HYNDS, RJ YATES, TS RICHARDSON, IG SANDERSON, TR WENZEL, KP MCCOMAS, DJ TSURUTANI, BT TI COMETARY WATER-GROUP IONS IN THE REGION SURROUNDING COMET GIACOBINI-ZINNER - DISTRIBUTION-FUNCTIONS AND BULK PARAMETER ESTIMATES SO PLANETARY AND SPACE SCIENCE LA English DT Article ID SOLAR-WIND PLASMA; FREQUENCY ELECTROMAGNETIC-WAVES; MAGNETIC-FIELD OBSERVATIONS; HALLEY BOW SHOCK; P/GIACOBINI-ZINNER; ENERGETIC IONS; PICKUP IONS; HEAVY-IONS; ISEE-C; INSITU OBSERVATIONS AB The bulk parameters (number density and thermal energy density) of cometary water-group ions in the region surrounding comet Giacobini-Zinner have been derived using data from the EPAS instrument on the ICE spacecraft. The derivation is based on the assumption that the pick-up ion distribution function is isotropic in the frame of the bulk flow, an approximation which has previously been shown to be reasonable within approximately 4 x 10(5) km of the comet nucleus along the spacecraft trajectory (corresponding to +/- 5 h about closest approach). Bulk parameter determinations are consequently restricted to this region, which corresponds physically to the inner part of the region of cometary ion pick-up in the solar wind flow, and the interior region of slowed, mass-loaded flow. The transition between the pick-up and mass-loaded regions occurs at the cometary shock, which was traversed at a cometocentric distance of approximately 1 x 10(5) km along the spacecraft track (+/- 85 min about closest approach). Examination of the ion distribution functions in this region, transformed to the bulk flow frame, indicates the occurrence of a "flattened" distribution in the vicinity of the local pick-up speed, and a steeply falling tail at speeds above, which may be approximated as an exponential in ion speed. Bulk parameters derived by integrating over these distributions have been compared with simple theoretical estimates based on ionization of the neutral coma of the comet by solar u.v. radiation, by charge exchange, and by electron impact, giving a combined ionization time-scale of approximately 10(6) s, followed by ion pick-up and isotropization in the solar wind flow. In the inner pick-up region the derived parameters are in good agreement with the theoretical estimates, within a factor of approximately 2, showing that no major additional sources of ionization, or major energization processes, are required to account for the results. Comparison of the thermal pressure of the water-group pick-up ions with the solar wind thermal pressure and with the magnetic pressure, shows how the pick-up ion pressure grows from small values at large distances from the comet, to become the dominant pressure component in the region just upstream from the shock. As a consequence, the magnetosonic Mach number falls from values of approximately 5 at large distances, down to approximately 2.5 just upstream of the shock. In the mass-loaded region downstream from the shock the observed ions most probably correspond to the relatively energetic population which is produced in the fast-flow region upstream from the shock, and which is subsequently convected downstream. Reasonable agreement between derived and theoretically-estimated bulk parameters is obtained in the outer part of the mass-loaded region on this basis. In the inner part of the mass-loaded region, however, within approximately 6 x 10(4) km of the comet (+/- 45 min about closest approach), the derived densities fall far below theoretical predictions, indicating that the energetic ions created in the upstream region must be actively removed from these stream-tubes by some process, at present undetermined. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. EUROPEAN SPACE AGCY,EUROPEAN SPACE RES & TECHNOL CTR,DEPT SPACE SCI,2200 AG NOORDWIJK,NETHERLANDS. UNIV CALIF LOS ALAMOS SCI LAB,LOS ALAMOS,NM 87545. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP STAINES, K (reprint author), UNIV LONDON IMPERIAL COLL SCI & TECHNOL,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. OI Richardson, Ian/0000-0002-3855-3634 NR 62 TC 9 Z9 9 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0032-0633 J9 PLANET SPACE SCI JI Planet Space Sci. PD MAR PY 1991 VL 39 IS 3 BP 479 EP 506 DI 10.1016/0032-0633(91)90008-X PG 28 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FF040 UT WOS:A1991FF04000008 ER PT J AU SCHAEFER, BE AF SCHAEFER, BE TI ECLIPSE EARTHSHINE SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Note DE MOON; EARTHSHINE AB Earthshine is the sunlight reflected off the Earth's surface that illuminates the dark side of the Moon. In this paper I predict that the earthshine is sufficiently bright during a total solar eclipse that lunar maria and craters can be distinguished visually and photographically. The predicted contrast ratio for prominent lunar features is typically 0.06. Proper shielding from glare and reasonable magnification are prerequisites for success. RP SCHAEFER, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 11 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 MAR PY 1991 VL 103 IS 661 BP 315 EP 316 DI 10.1086/132823 PG 2 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FE564 UT WOS:A1991FE56400009 ER PT J AU SCHAEFER, BE AF SCHAEFER, BE TI SUNSPOT VISIBILITY SO QUARTERLY JOURNAL OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article ID RECORDS; SEARCH AB The Oriental record of sunspots visible to the naked eye stretches over two millennia and is the only available long-term record of solar activity. As such, this unique record is invaluable for studies of correlations between climate and solar activity. Unfortunately, there are difficulties in knowing the frequency of observation as well as the real capabilities of the human eye for detecting sunspots. This paper advances a detailed theory of sunspot visibility based on the physiology of the human eye. I find that the average person under optimal conditions can detect a sunspot whose penumbral diameter is as small as 27". The technique for filtering the sunlight, the observer's diet, age, and amount of close-up reading will not change sunspot visibility in practical cases, so the modern observations and theory are fully comparable with the ancient Chinese observations. C1 UNIV SPACE RES ASSOC,COLUMBIA,MD. RP SCHAEFER, BE (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 661,GREENBELT,MD 20771, USA. NR 39 TC 11 Z9 11 U1 1 U2 3 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0035-8738 J9 Q J ROY ASTRON SOC JI Q. J. R. Astron. Soc. PD MAR PY 1991 VL 32 IS 1 BP 35 EP 44 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FC611 UT WOS:A1991FC61100004 ER PT J AU SHORT, DA MENGEL, JG CROWLEY, TJ HYDE, WT NORTH, GR AF SHORT, DA MENGEL, JG CROWLEY, TJ HYDE, WT NORTH, GR TI FILTERING OF MILANKOVITCH CYCLES BY EARTHS GEOGRAPHY SO QUATERNARY RESEARCH LA English DT Article ID GENERAL-CIRCULATION MODEL; LAST CLIMATIC CYCLE; VOSTOK ICE CORE; ORBITAL VARIATIONS; PRECESSION CYCLE; ATLANTIC-OCEAN; AGE; SENSITIVITY; SHEETS; INSOLATION C1 APPL RES CORP,LANDOVER,MD 20785. APPL RES CORP,COLLEGE STN,TX 77840. TEXAS AGR EXPTL STN,DEPT METEOROL,CLIMATE SYST RES PROGRAM,COLLEGE STN,TX 77843. RP SHORT, DA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. RI North, Gerald/G-1019-2011 NR 49 TC 181 Z9 201 U1 6 U2 20 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 MAR PY 1991 VL 35 IS 2 BP 157 EP 173 DI 10.1016/0033-5894(91)90064-C PG 17 WC Geography, Physical; Geosciences, Multidisciplinary SC Physical Geography; Geology GA FB564 UT WOS:A1991FB56400001 ER PT J AU HARDING, AK AF HARDING, AK TI PHYSICS IN STRONG MAGNETIC-FIELDS NEAR NEUTRON-STARS SO SCIENCE LA English DT Article ID GAMMA-RAY BURSTS; PAIR ANNIHILATION; CYCLOTRON; SPECTRA; SCATTERING; LINES; PULSARS AB Electromagnetic phenomena occurring in the strong magnetic fields of neutron stars are currently of great interest in high-energy astrophysics. Observations of rotation rate changes and cyclotron lines in pulsars and gamma-ray bursts indicate that surface magnetic fields of neutron stars often exceed 10(12) gauss. In fields this strong, where electrons behave much as if they were in bound atomic states, familiar processes undergo profound changes, and exotic processes become important. Strong magnetic fields affect the physics in several fundamental ways: Energies perpendicular to the field are quantized, transverse momentum is not conserved, and electron-positron spin is important. Neutron stars therefore provide a unique laboratory for the study of physics in extremely high fields that cannot be generated on Earth. RP HARDING, AK (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RI Harding, Alice/D-3160-2012 NR 35 TC 26 Z9 26 U1 0 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 EI 1095-9203 J9 SCIENCE JI Science PD MAR 1 PY 1991 VL 251 IS 4997 BP 1033 EP 1038 DI 10.1126/science.251.4997.1033 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA EZ665 UT WOS:A1991EZ66500039 PM 17802087 ER PT J AU PARFITT, LJ SMIALEK, JL NIC, JP MIKKOLA, DE AF PARFITT, LJ SMIALEK, JL NIC, JP MIKKOLA, DE TI OXIDATION BEHAVIOR OF CUBIC PHASES FORMED BY ALLOYING AL3TI WITH CR AND MN SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP PARFITT, LJ (reprint author), MICHIGAN TECHNOL UNIV,DEPT MET & MAT ENGN,HOUGHTON,MI 49931, USA. NR 11 TC 35 Z9 37 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 MAR PY 1991 VL 25 IS 3 BP 727 EP 731 DI 10.1016/0956-716X(91)90123-I PG 5 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA EZ877 UT WOS:A1991EZ87700043 ER PT J AU LAYDEN, AC FOX, PA HOWARD, JM SARAJEDINI, A SCHATTEN, KH SOFIA, S AF LAYDEN, AC FOX, PA HOWARD, JM SARAJEDINI, A SCHATTEN, KH SOFIA, S TI DYNAMO-BASED SCHEME FOR FORECASTING THE MAGNITUDE OF SOLAR-ACTIVITY CYCLES SO SOLAR PHYSICS LA English DT Article ID SUNSPOT NUMBER; MAGNETIC-FIELD; QUIET-DAYS; MAXIMUM; PREDICTION; INTENSITY; FACULAE; INDEXES; MODEL; SUN AB In this paper we present a general framework for forecasting the smoothed maximum level of solar activity in a given cycle, based on a simple understanding of the solar dynamo. This type of forecasting requires knowledge of the Sun's polar magnetic field strength at the preceeding activity minimum. Because direct measurements of this quantity are difficult to obtain, we evaluate the quality of a number of proxy indicators already used by other authors which are physically related to the Sun's polar field. We subject these indicators to a rigorous statistical analysis, and specify in detail the analysis technique for each indicator in order to simplify and systematize reanalysis for future use. We find that several of these proxies are in fact poorly correlated or uncorrelated with solar activity, and thus are of little value for predicting activity maxima. We also present a scheme in which the predictions of the individual proxies are combined via an approximately weighted mean to produce a compound prediction. We then apply the scheme to the current cycle 22, and estimate a maximum smoothed International sunspot number of 171 +/- 26, which can be expressed alternatively as a smoothed 2800 MHz radio flux (F10.7) of 211 +/- 23 x (10(-22) W m-2 Hz-1), or as a smoothed sunspot area of 2660 +/- 430 millionths of a solar disk. Once the actual maximum for cycle 22 has been established, we will have both additional statistics for all the proxy indicators, and a clearer indication of how accurately the present scheme can predict solar activity levels. C1 NASA,GODDARD SPACE FLIGHT CTR,LASP,GREENBELT,MD 20771. RP LAYDEN, AC (reprint author), YALE UNIV,CTR SOLAR & SPACE RES,POB 6666,NEW HAVEN,CT 06511, USA. OI Fox, Peter/0000-0002-1009-7163 NR 54 TC 44 Z9 44 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0038-0938 J9 SOL PHYS JI Sol. Phys. PD MAR PY 1991 VL 132 IS 1 BP 1 EP 40 DI 10.1007/BF00159127 PG 40 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA FA329 UT WOS:A1991FA32900001 ER PT J AU CHOUDHURY, BJ AF CHOUDHURY, BJ TI PASSIVE MICROWAVE REMOTE-SENSING CONTRIBUTION TO HYDROLOGICAL VARIABLES SO SURVEYS IN GEOPHYSICS LA English DT Review ID VEGETATION; EMISSION; FIELDS AB Physical principles governing passive microwave remote sensing of hydrological variables are outlined and illustrated by actual observations by ground-based, air-borne and space-borne microwave radiometers operating at different frequencies. Specific hydrological variables addressed in this paper are soil moisture, seasonal inundation of rivers and swamps, vegetation, snow, and rainfall. Passive remote sensing provides measurements of electromagnetic radiation emitted by the land-atmosphere system, which can be related more directly to the radiative characteristics of the system than to physical or physiological characteristics. Estimation of hydrological variables from microwave observations necessarily involves models relating the radiative to the physical characteristics, and in general more than one physical characteristics determine the microwave observations. This non-uniqueness in the relationship between microwave observations to a particular hydrological variable leads to uncertainties in the estimation of the variable. Notwithstanding this limitation, the principles and the examples given in this paper illustrate the value of passive microwave observations to regional and global hydrology at a temporal resolution of days aggregated to a decade. RP CHOUDHURY, BJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROL SCI BRANCH,GREENBELT,MD 20771, USA. NR 38 TC 30 Z9 30 U1 0 U2 4 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0169-3298 J9 SURV GEOPHYS JI Surv. Geophys. PD MAR PY 1991 VL 12 IS 1-3 BP 63 EP 84 DI 10.1007/BF01903412 PG 22 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA EU405 UT WOS:A1991EU40500004 ER PT J AU TURCO, RP TOON, OB ACKERMAN, TR POLLACK, JB SAGAN, C AF TURCO, RP TOON, OB ACKERMAN, TR POLLACK, JB SAGAN, C TI CLIMATE AND SMOKE - AN APPRAISAL OF NUCLEAR WINTER SO USPEKHI FIZICHESKIKH NAUK LA Russian DT Review ID GENERAL-CIRCULATION MODEL; PARTICULATE ELEMENTAL CARBON; SIZE-SEGREGATED MEASUREMENTS; TWO-DIMENSIONAL SIMULATIONS; AEROSOL LIGHT-ABSORPTION; REMOTE ARCTIC LOCATIONS; 10.6-MU M WAVELENGTHS; OPTICAL-PROPERTIES; ACETYLENE SMOKE; DUST STORMS C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. PENN STATE UNIV, UNIVERSITY PK, PA 16802 USA. CORNELL UNIV, ITHACA, NY 14853 USA. RP UNIV CALIF LOS ANGELES, LOS ANGELES, CA 90024 USA. NR 247 TC 0 Z9 0 U1 0 U2 1 PU MEZHDUNARODNAYA KNIGA PI MOSCOW PA 39 DIMITROVA UL., MOSCOW, 113095, RUSSIA SN 0042-1294 J9 USP FIZ NAUK+ JI Uspekhi Fiz. Nauk PD MAR PY 1991 VL 161 IS 3 BP 89 EP 123 PG 35 WC Physics, Multidisciplinary SC Physics GA GK426 UT WOS:A1991GK42600005 ER PT J AU VANDEGRIEND, AA OWE, M GROEN, M STOLL, MP AF VANDEGRIEND, AA OWE, M GROEN, M STOLL, MP TI MEASUREMENT AND SPATIAL VARIATION OF THERMAL INFRARED SURFACE EMISSIVITY IN A SAVANNA ENVIRONMENT SO WATER RESOURCES RESEARCH LA English DT Article ID WATER; SOILS; BAND AB Knowledge of the surface thermal emissivity is necessary for the application of thermal infrared remote sensing, which forms the basis for water and surface energy balance monitoring from space. Thermal emissivity was measured in the wavelength band 8-14-mu-m for a series of representative surfaces within a natural bush-savanna environment intermixed with cultivated fields in Botswana. The measurements were performed with an emissivity box, which may be constructed with different dimensions to meet the general requirements of the user. The device is well-suited for bare soil, grass, and other types of soil and low-vegetation cover combinations. The measured emissivity varied between 0.914 for bare soil (loamy sand) and 0.986 for a surface completely covered with savanna shrub (Euclea undulata). Calculations are based on the measurements of the radiative surface temperature of three different reflecting configurations of the box. Repetitive estimates of the emissivity were found to be very reproducible for the same surface types and showed the large spatial variability of surface emissivity within the study area. This paper describes the emissivity box together with other versions of the box concept found in the literature, and it describes the operation and calibration procedure as well as the results and consequences of the emissivity measurements for the application of thermal infrared remote sensing. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV STRASBOURG 1,SCI TELEDETECT SPATIALE,F-67070 STRASBOURG,FRANCE. RP VANDEGRIEND, AA (reprint author), FREE UNIV AMSTERDAM,INST EARTH SCI,1007 MC AMSTERDAM,NETHERLANDS. NR 23 TC 19 Z9 19 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0043-1397 J9 WATER RESOUR RES JI Water Resour. Res. PD MAR PY 1991 VL 27 IS 3 BP 371 EP 379 DI 10.1029/90WR02616 PG 9 WC Environmental Sciences; Limnology; Water Resources SC Environmental Sciences & Ecology; Marine & Freshwater Biology; Water Resources GA FA001 UT WOS:A1991FA00100012 ER PT J AU PUTCHA, L CINTRON, NM AF PUTCHA, L CINTRON, NM TI PHARMACOKINETIC CONSEQUENCES OF SPACEFLIGHT SO ANNALS OF THE NEW YORK ACADEMY OF SCIENCES LA English DT Article ID ACETAMINOPHEN RP PUTCHA, L (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,MAIL CODE SD4,HOUSTON,TX 77058, USA. NR 6 TC 10 Z9 11 U1 0 U2 2 PU NEW YORK ACAD SCIENCES PI NEW YORK PA 2 E 63RD ST, NEW YORK, NY 10021 SN 0077-8923 J9 ANN NY ACAD SCI JI Ann. N.Y. Acad. Sci. PD FEB 28 PY 1991 VL 618 BP 615 EP 618 DI 10.1111/j.1749-6632.1991.tb27292.x PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA FQ403 UT WOS:A1991FQ40300061 PM 11537657 ER PT J AU SUI, CH LAU, KM BETTS, AK AF SUI, CH LAU, KM BETTS, AK TI AN EQUILIBRIUM-MODEL FOR THE COUPLED OCEAN-ATMOSPHERE BOUNDARY-LAYER IN THE TROPICS SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID PACIFIC-OCEAN; MIXED LAYER; HEAT FLUXES AB A coupled model is used to study the equilibrium state of the ocean-atmosphere boundary layer in the tropics. The atmospheric model is a one-dimensional thermodynamic model for a partially mixed, partly cloudy convective boundary layer (CBL), including the effects of cloud-top subsidence, surface momentum and heat (latent and sensible) fluxes, and realistic radiative transfer for both shortwaves and longwaves (Betts and Ridgway, 1988; 1989). The oceanic model is a thermodynamic model for a well-mixed layer, with a closure constraint based on a one-dimensional turbulent kinetic energy (TKE) equation following Kraus and Turner (1967). Results of several sets of experiments are reported in this paper. In the first two sets of experiments, with sea surface temperature (SST) specified, we solve the equilibrium state of the coupled system as a function of SST for a given surface wind (case 1) and as a function of surface wind for a given SST (case 2). In both cases the depth of the CBL and the ocean mixed layer (OML) increases and the upwelling below the OML decreases, corresponding to either increasing SST or increasing surface wind. The deepening of the equilibrium CBL is primarily linked to the increase of CBL moisture with increasing SST and surface wind. The increase of OML depth and decrease of upwelling are due to a decrease of net downward heat flux with increasing SST and the generation of TKE by increasing wind. In another two sets of experiments, we solve for the coupled ocean-atmosphere model iteratively as a function of surface wind for a fixed upwelling (case 3) and a fixed OML depth (case 4). SST falls with increasing wind in both cases, but the fall is steeper in case 4, because the OML depth is fixed, whereas in case 3 the depth is allowed to deepen and the cooling is spread over a larger mass of water. The decrease of evaporation with increasing wind in case 4 leads to a very dry and shallow CBL. Results of further experiments with surface wind and SST (upwelling) prescribed as a function of longitude similar to the observed values across the Pacific show that the model gives realistic gradients of mixed-layer depth and upwelling (SST). This work suggests that the equilibrium state of the coupled system is very sensitive to the coupling of the boundary layers. Special efforts are needed to incorporate physical processes in the CBL and OML in coupled models. RP SUI, CH (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 913, GREENBELT, MD 20771 USA. OI SUI, CHUNG-HSIUNG/0000-0003-2842-5660 NR 19 TC 14 Z9 14 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD FEB 28 PY 1991 VL 96 SU S BP 3151 EP 3163 PG 13 WC Oceanography SC Oceanography GA FB521 UT WOS:A1991FB52100003 ER PT J AU LAU, KM NAKAZAWA, T SUI, CH AF LAU, KM NAKAZAWA, T SUI, CH TI OBSERVATIONS OF CLOUD CLUSTER HIERARCHIES OVER THE TROPICAL WESTERN PACIFIC SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID DIURNAL-VARIATION; DYNAMICS; OSCILLATIONS; CONVECTION; GATE; ENSO AB Infrared radiance measurements at cloud top by the Japanese Geostationary Meteorological Satellite (GMS) were used to study the structure and propagation of tropical convective systems over the equatorial western Pacific. Results indicate that tropical convection in this region possess three fundamental periodicities: 1 day, 2-3 days, and 10-15 days. Cloud clusters within these convective systems interact to produce a hierarchy of collective motions covering all of these three basic time scales. The 10- to 15-day time scale is closely related to the intraseasonal (or 30-60 day) oscillations that propagate from the Indian Ocean to the western Pacific along the equator all year round. Large convective complexes known as supercloud clusters (SCC) are found to organize in the 10- to 15-day time scale, especially over the open, warm water of the western/central Pacific (160-degrees-E to 180-degrees). The SCCs generally propagate eastward, although occasionally they can also propagate westward. The zonal propagation can occur either continuously or intermittently. In both cases the SCC is found to be made up of several well-organized cloud clusters, which are generated at 2- to 3-day intervals and propagate in the opposite direction to the SCC. The diurnal variation is most pronounced over the maritime continent, although significant amplitudes are also found over the open ocean. The amplitude of the diurnal cycle is strongly modulated by the 2- to 3-day and 10- to 15-day oscillations. Advanced spectral analysis methods applied to convective indices derived from the radiance data confirm this hierarchical structure in cloud clusters in the tropical western Pacific. In addition to the embedding of well-organized clusters within a SCC in the spatial domain, there is also a similar embedding by successive longer scales in the time domain. Interactions between the major frequency groups appear also to give rise to intermediate frequency variations. A discussion of the present results in the context of equatorial wave dynamics of the moist tropical atmosphere is also presented. C1 METEOROL RES INST, TSUKUBA, IBARAKI 305, JAPAN. RP NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 913, GREENBELT, MD 20771 USA. RI nakazawa, tetsuo/P-9063-2014; OI SUI, CHUNG-HSIUNG/0000-0003-2842-5660 NR 18 TC 69 Z9 70 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9275 EI 2169-9291 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD FEB 28 PY 1991 VL 96 SU S BP 3197 EP 3208 PG 12 WC Oceanography SC Oceanography GA FB521 UT WOS:A1991FB52100007 ER PT J AU HILL, YD FREISER, BS BAUSCHLICHER, CW AF HILL, YD FREISER, BS BAUSCHLICHER, CW TI UNEXPECTED DISPLACEMENT OF ALKENES BY ALKANES IN THE REACTIONS OF Y(ALKENE)2+ - AN EXPERIMENTAL AND THEORETICAL-STUDY SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID TRANSFORM MASS-SPECTROMETRY; GAS-PHASE; MOLECULAR CALCULATIONS; METAL-IONS; ENERGY; ORBITALS; ATOMS AB Ligand-displacement reactions in the gas phase using Fourier transform mass spectrometry yield the following metal-ligand bond energy order for Y2+: CH4, C2H6 < C2H2, C2H4 < C3H8 < C3H6 < C4H10 < C4H6. The unexpected displacement of alkenes by alkanes in the reactions of Y (alkene)2+ is explained by a detailed theoretical treatment, which indicates that Y2+ binds primarily by electrostatic interactions. As an aid to the discussion, Sc2+ and Cu+ are also considered. C1 PURDUE UNIV,DEPT CHEM,W LAFAYETTE,IN 47907. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 30 TC 45 Z9 45 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD FEB 27 PY 1991 VL 113 IS 5 BP 1507 EP 1510 DI 10.1021/ja00005a005 PG 4 WC Chemistry, Multidisciplinary SC Chemistry GA EZ477 UT WOS:A1991EZ47700005 ER PT J AU FISHMAN, GJ HARMON, BA GREGORY, JC PARNELL, TA PETERS, P PHILLIPS, GW KING, SE AUGUST, RA RITTER, JC CUTCHIN, JH HASKINS, PS MCKISSON, JE ELY, DW WEISENBERGER, AG PIERCEY, RB DYBLER, T AF FISHMAN, GJ HARMON, BA GREGORY, JC PARNELL, TA PETERS, P PHILLIPS, GW KING, SE AUGUST, RA RITTER, JC CUTCHIN, JH HASKINS, PS MCKISSON, JE ELY, DW WEISENBERGER, AG PIERCEY, RB DYBLER, T TI OBSERVATION OF BE-7 ON THE SURFACE OF LDEF SPACECRAFT SO NATURE LA English DT Article ID TROPOSPHERE; BERYLLIUM-7; STRATOSPHERE; TRANSPORT; EXCHANGE; AIR AB THE Long Duration Exposure Facility (LDEF), an orbiting unmanned satellite, was recently returned to Earth after almost six years in space. From radioactivity measurements, we have found significant quantities of the isotope Be-7 on the leading edge (but only on the leading edge) of LDEF. Although the absolute atmospheric concentration of Be-7 needed to explain this detection is extremely small (10(-7) atoms cm-3), it concentration of LDEF's altitude (310 km) must be several orders of magnitude higher than in the stratosphere below, where it is produced by cosmic-ray reactions with atmospheric nitrogen and oxygen nuclei. To explain the presence of Be-7 on the surface of LDEF, it must first be rapidly and efficiently transported to high altitudes, and then adsorbed onto the surface of the spacecraft. Neither process had been expected. Our detection may therefore lead to the use of Be-7 as an exo-atmospheric tracer, as well as to studies of surface interactions in space. C1 UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35806. UNIV ALABAMA,DEPT CHEM,HUNTSVILLE,AL 35899. SACHS FREEMAN ASSOCIATES INC,WASHINGTON,DC 20375. UNIV FLORIDA,GAINESVILLE,FL 32609. INST SPACE SCI & TECHNOL,GAINESVILLE,FL 32609. MISSISSIPPI STATE UNIV,DEPT PHYS,MISSISSIPPI STATE,MS 39762. USN,RES LAB,WASHINGTON,DC 20375. RP FISHMAN, GJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,CODE ES62,HUNTSVILLE,AL 35812, USA. NR 17 TC 10 Z9 10 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD FEB 21 PY 1991 VL 349 IS 6311 BP 678 EP 680 DI 10.1038/349678a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA EY627 UT WOS:A1991EY62700040 ER PT J AU COFER, WR LEVINE, JS WINSTEAD, EL STOCKS, BJ AF COFER, WR LEVINE, JS WINSTEAD, EL STOCKS, BJ TI NEW ESTIMATES OF NITROUS-OXIDE EMISSIONS FROM BIOMASS BURNING SO NATURE LA English DT Article ID TRACE GAS EMISSIONS; CLIMATE CHANGE; COMBUSTION AB ATMOSPHERIC nitrous oxide is important because of its role in stratospheric ozone destruction 1 and because it is a greenhouse gas. 2,3. Measurements indicate that N2O is increasing in the atmosphere at a rate of approximately 0.2% yr-1 (ref. 4). Fossil-fuel combustion and biomass burning 5,6 have been considered to be significant global sources of N2O, but the recent discovery of an artefact producing increased levels of N2O in combustion gas samples collected and stored in grab bottles before chemical analysis 7,8 has resulted in the downgrading of a fossil-fuel combustion and the questioning of biomass burning as important sources of N2O 9,10. As almost all reported analyses of N2O produced from biomass burning have involved essentially the same collection and analysis protocols as used in the fossil-fuel studies, this source of N2O must also be re-examined. Here we report and compare measurement of N2O made over a large prescribed fire using a near real-time in situ measurement technique with measurements of N2O from simultaneously collected grab-bottle samples. The results from 27 small laboratory biomass test fires also help clarify the validity of earlier assessments. We conclude that biomass burning contributes approximately 7% of atmospheric N2O, as opposed to earlier estimates of several times this value 6. C1 ST SYST CORP,HAMPTON,VA 23666. FORESTRY CANADA,GREAT LAKES FORESTRY CTR,SAULT ST MARIE P6A 5M7,ONTARIO,CANADA. RP COFER, WR (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 17 TC 36 Z9 36 U1 3 U2 15 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD FEB 21 PY 1991 VL 349 IS 6311 BP 689 EP 691 DI 10.1038/349689a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA EY627 UT WOS:A1991EY62700045 ER PT J AU RUDAZ, S STECKER, FW AF RUDAZ, S STECKER, FW TI ON THE OBSERVABILITY OF THE GAMMA-RAY LINE FLUX FROM DARK MATTER ANNIHILATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE DARK MATTER; GAMMA-RAYS, GENERAL; RADIATION MECHANISMS ID PHOTINO ANNIHILATION; LIMITS; MASSES; COSMOLOGY; UNIVERSE; PHOTONS; PARTICLES; HALO AB We discuss the limits on the possible cosmic gamma-ray line flux from the two-photon annihilation of dark matter in the Galaxy. These limits are derived using both particle physics and cosmological constraints on dark matter candidates which arise in supersymmetric extensions of the standard model of particle physics. Our results are given in terms of allowed and proscribed areas in the flux-energy plane. We then use these bounds to consider the observability of the line flux above continuum background fluxes using future high-resolution gamma-ray telescopes. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP RUDAZ, S (reprint author), UNIV MINNESOTA,SCH PHYS & ASTRON,MINNEAPOLIS,MN 55455, USA. RI Stecker, Floyd/D-3169-2012 NR 25 TC 43 Z9 43 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 FEB 20 PY 1991 VL 368 IS 2 BP 406 EP 410 DI 10.1086/169705 PN 1 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX185 UT WOS:A1991EX18500010 ER PT J AU RYU, D VISHNIAC, ET AF RYU, D VISHNIAC, ET TI THE DYNAMIC INSTABILITY OF ADIABATIC BLAST WAVES SO ASTROPHYSICAL JOURNAL LA English DT Article DE HYDRODYNAMICS; INSTABILITIES; INTERSTELLAR, MATTER; NEBULAE, PLANETARY; SHOCK WAVES; STARS, SUPERNOVAE ID RAYLEIGH-TAYLOR INSTABILITY; SELF-SIMILAR FLOW; SUPERNOVA 1987A; SHOCK-WAVES; SN 1987A; STABILITY; FRAGMENTATION; EXPANSION; SN-1987A; SN1987A AB Adiabatic blast waves, which have a total energy injected from the center, E proportional-to t(q), and propagate through a preshock medium with a density P(E) proportional-to tau-omega, are described by a family to similarity solutions. Previous work has shown that adiabatic blast waves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. In this paper we consider the stability of adiabatic blast waves with a decreasing postshock entropy. Such blast waves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blast waves also have such a region, depending on the values of q, omega, and gamma, where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blast waves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blast waves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blast waves have been calculated. We discuss the implications of this work for two astrophysical interests, the instability of shocks propagating through supernova envelopes and the evolution of planetary nebulae. C1 UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. RP RYU, D (reprint author), FERMI NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,MS 209,POB 500,BATAVIA,IL 60510, USA. RI Ryu, Dongsu/C-2270-2016 OI Ryu, Dongsu/0000-0002-5455-2957 NR 37 TC 39 Z9 39 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 FEB 20 PY 1991 VL 368 IS 2 BP 411 EP 425 DI 10.1086/169706 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX185 UT WOS:A1991EX18500011 ER PT J AU ARENDT, RG DWEK, E PETRE, R AF ARENDT, RG DWEK, E PETRE, R TI AN INFRARED-ANALYSIS OF PUPPIS-A SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOURCES; INTERSTELLAR, GRAINS; NEBULAE, INDIVIDUAL (PUPPIS-A); NEBULAE, SUPERNOVA REMNANTS; RADIATION MECHANISMS ID SUPER-NOVA REMNANTS; TEMPERATURE-FLUCTUATIONS; INTERSTELLAR GRAINS; RADIO OBSERVATIONS; HOT GAS; EMISSION; CATALOG; CIRRUS; STARS AB We have completed a quantitative analysis of the infrared emission of the supernova remnant (SNR) Puppis A as seen by the Infrared Astronomical Satellite (IRAS). We estimate physical parameters of the remnant (and the surrounding interstellar medium), including density, mass, temperature, and age. The infrared spectrum of Puppis A is fit by models of thermal emission from interstellar dust grains which have been swept up into the SNR where they are collisionally heated by the shocked gas. We find evidence of an enhanced abundance of very small grains in the interstellar medium near Puppis A, and evidence of their destruction by the advancing blast wave. C1 NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. RP ARENDT, RG (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. NR 34 TC 22 Z9 22 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA DIRAC HOUSE, TEMPLE BACK, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 1991 VL 368 IS 2 BP 474 EP 485 DI 10.1086/169712 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX185 UT WOS:A1991EX18500017 ER PT J AU HARVEY, PM LESTER, DF BROCK, D JOY, M AF HARVEY, PM LESTER, DF BROCK, D JOY, M TI DUST PROPERTIES AROUND EVOLVED STARS FROM FAR-INFRARED SIZE LIMITS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOURCES; INTERSTELLAR, GRAINS; STARS, CIRCUMSTELLAR SHELLS ID IRC + 10216; MASS-LOSS; IRC+10216; CRL-2688; EMISSION; NEBULAE; GRAINS; ENVELOPES; SHELLS; CLOUDS AB We have obtained high angular resolution far-infrared scans of six stars surrounded by circumstellar dust shells believed to result from mass loss by the central star. None of the dust shells was clearly resolved at either 50-mu-m or 100-mu-m; the upper limits are in the range 4" to 10". These size limits place constraints on the far-IR dust emissivity and dust density distribution. For one of the objects, AFGL 2343, larger than normal grains are almost certainly required. For several other stars the size limits are much more consistent with dust having an emissivity law no steeper than lambda--1 in the 1-100-mu-m spectral region. For IRC + 10216 we confirm an earlier suggestion that, assuming reasonable grain properties, a smooth radial dust distribution is not consistent with our scans and the energy distribution of the object. C1 OBSERV GRENOBLE,GRP ASTROPHYS GRENOBLE,GRENOBLE,FRANCE. JOINT ASTRON CTR,HILO,HI 96720. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB ES65,HUNTSVILLE,AL 35812. RP HARVEY, PM (reprint author), UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712, USA. NR 29 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 FEB 20 PY 1991 VL 368 IS 2 BP 558 EP 563 DI 10.1086/169719 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX185 UT WOS:A1991EX18500024 ER PT J AU SIMPSON, JP AF SIMPSON, JP TI IRAS LOW-RESOLUTION SPECTRAL OBSERVATIONS OF THE 10 AND 18 MICRON SILICATE EMISSION FEATURES SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SPECTRA; STARS, CIRCUMSTELLAR SHELLS ID INFRARED SPECKLE INTERFEROMETRY; LATE-TYPE STARS; OPTICAL-PROPERTIES; CARBONACEOUS CHONDRITES; INTERSTELLAR EXTINCTION; OH MASERS; MU-CEPHEI; DUST; GRAINS; ENVELOPES AB The IRAS LRS Atlas contains 8-23-mu-m spectra of 1816 stars with silicate emission features. In order to study the shapes of the silicate dust features, the 117 stars whose emission features appear to be optically thin and which have the best signal-to-noise ratio at the longest wavelengths were analyzed. Simple spherical dust shell models were calculated in both the optically thin and the slightly optically thick approximations. From the comparison of the predicted spectra of the dust plus stellar continuum, the emissivity function kappa-lambda was derived. In the different stars, the shape of the 10-mu-m feature is either narrow or broad and it is peaked either at approximately 9.7-mu-m or at 10-mu-m. Either particle size effects (particles greater-than-or-similar-to 0.75-mu-m in radius) or optical depth effects (central optical depth approximately 1) could broaden the 10-mu-m feature. Chemical composition differences no doubt are also important, particularly as regards the position of the peak of the 10-mu-m feature. The stars with the peak at 10-mu-m are more closely confined to the Galactic plane than the stars with the peak at 9.7-mu-m. The shape of the 18-mu-m feature is essentially the same in all stars, and can be used to extend the interstellar extinction curve past 13-mu-m to 22-mu-m. C1 UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. RP SIMPSON, JP (reprint author), NASA,AMES RES CTR,ASTROPHYS EXPT BRANCH,MS 245-6,MOFFETT FIELD,CA 94035, USA. NR 51 TC 50 Z9 50 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 FEB 20 PY 1991 VL 368 IS 2 BP 570 EP 579 DI 10.1086/169721 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX185 UT WOS:A1991EX18500026 ER PT J AU TRIPP, TM SHEMANSKY, DE JAMES, GK AJELLO, JM AF TRIPP, TM SHEMANSKY, DE JAMES, GK AJELLO, JM TI COLLISIONAL EXCITATION AND RADIATIVE PROPERTIES OF N-II - THE STRONG INTERCOMBINATION ((1)D-(3)P(0)) TRANSITION AT 748-A SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; TRANSITION RATES; ULTRAVIOLET, SPECTRA ID EXTREME ULTRAVIOLET DAYGLOW; ACTIVE SOLAR CONDITIONS; LOW-DENSITY PLASMA; VACUUM ULTRAVIOLET; ELECTRON-IMPACT; CROSS-SECTIONS; BEAM-FOIL; OSCILLATOR-STRENGTHS; IONIZED NITROGEN; SPECTRUM AB We have constructed a collisional radiative model, using a combination of theoretical calculations and experimental measurements, in order to calculate the excitation and emission properties of electron impact on N II. We have also conducted a spectrometric experiment in order to verify theoretical calculations predicting strong configuration interaction effects, and we find that the measured strength of the N II intercombination transition 2s(2)2p2 1D-2s(2)2p(2P)3s 3P0 at 748.37 angstrom is comparable to the electric dipole multiplet 2s(2)2p2 3P-2s(2)2p(2P)3s 3P0 at 671 angstrom. The measured branching ratio for the 1D-3P0 (J = 1) transition is 0.29 +/- 0.15, in agreement with recent theoretical calculations by Fawcett. Beam foil lifetime measurements for the 3s 3P0 state are also in agreement with the theoretical calculations. This is a remarkably strong intercombination transition for such a light element. If enough strong intercombination transitions of this type exist in the carbon isoelectronic sequence, diagnostic data and collisional radiative quantities could be affected with important astrophysical ramifications. We have employed this finding and our model in a preliminary calculation N II radiative cooling and rate coefficients, and we have examined how the N II temperature diagnostic lines might be affected by intercombination cascading. In respect to planetary atmospheres research, we briefly discuss the excitation and radiative properties of N II excited directly by electrons and by electron dissociative ionization excitation of N2. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP TRIPP, TM (reprint author), UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721, USA. NR 61 TC 9 Z9 9 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 1991 VL 368 IS 2 BP 641 EP 651 DI 10.1086/169731 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EX185 UT WOS:A1991EX18500036 ER PT J AU ALLEN, M DELITSKY, ML AF ALLEN, M DELITSKY, ML TI INFERRING THE ABUNDANCES OF CLO AND HO2 FROM SPACELAB-3 ATMOSPHERIC TRACE MOLECULE SPECTROSCOPY OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID INSITU DETECTION; STRATOSPHERE; OH; DERIVATION; PROFILES; NO2 AB The vertical distributions of the important highly reactive stratospheric species, CIO and HO2, have been inferred from Spacelab 3 (May 1985) Atmospheric Trace Molecule Spectroscopy (ATMOS) measurements of more detectable radical and reservoir species. A simple steady state algebraic expression for ClO, utilizing the observed ClONO2/NO2 abundance ratio, approximates the ClO results of a time-dependent photochemical model at sunset (30-degrees-N). Balloon measurements of ClO and comparisons of time-dependent photochemical model calculations of ClONO2 and HCl with the corresponding ATMOS profiles suggest that the actual ClO values are less than the time-dependent model profiles for ClO at sunset and sunrise (47-degrees-S). Errors in the current model simulation of the partitioning among the principal free chlorine species (HCl, ClONO2, and ClO) are indicated. However, a comparison of model results with observations of HOCl suggests that the calculated CiO abundance is not a significant overestimate of actual values. A similar methodology is applied to inferring the HO2 distribution, either algebraically using the ATMOS-measured HO2NO2/NO2 abundance ratio or numerically utilizing the time-dependent model. The algebraic results agree with the time-dependent model values to better than a factor of 2 at sunrise. The accuracy of the time-dependent model calculations of HO2 is suggested by the agreement between model results and ATMOS observations for HO2NO2 and balloon measurements of HO2. This confirms for the first time the procedure suggested previously by a number of authors of deriving HO(x) abundances from observed fields of O3 and H2O. C1 CALTECH, JET PROP LAB, DIV GEOL & PLANETARY SCI, PASADENA, CA 91109 USA. RP ALLEN, M (reprint author), CALTECH, JET PROP LAB, DIV EARTH & SPACE SCI, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 25 TC 12 Z9 12 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 20 PY 1991 VL 96 IS D2 BP 2913 EP 2919 DI 10.1029/90JD02369 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA EZ657 UT WOS:A1991EZ65700009 ER PT J AU CALLIS, LB BOUGHNER, RE NATARAJAN, M LAMBETH, JD BAKER, DN BLAKE, JB AF CALLIS, LB BOUGHNER, RE NATARAJAN, M LAMBETH, JD BAKER, DN BLAKE, JB TI OZONE DEPLETION IN THE HIGH-LATITUDE LOWER STRATOSPHERE - 1979-1990 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SOLAR ULTRAVIOLET IRRADIANCE; ELECTRONS; SAGE; SBUV; VALIDATION; MORPHOLOGY; SATELLITE; NITROGEN; MINIMUM; DOBSON AB Archived Stratospheric Aerosol and Gas Experiment (SAGE, SAGE II) and Solar and Backscattered Ultraviolet (SBUV) data are used to examine lower stratospheric O3 variations at 50-degrees latitude in both hemispheres. These data indicate that from 1979 to 1985, 73-90% of the total O3 changes have occurred below approximately 25 km in altitude. Significant O3 depletions (up to 15%) have occurred in the partial column (127-15.8 mbar) in both hemispheres with indications of a recovery after 1985. Both the SAGE/SAGE II and SBUV observations show essentially the same changes for this partial column. Below 20 km and between 1979 and 1985, larger local O3 depletions are suggested by the SAGE/SAGE II data sets. Temporally, the largest 365-day running mean O3 changes occur in 1982-1983 in the northern hemisphere and in late 1984 and early 1985 in both hemispheres. Possible explanations are discussed. Two-dimensional model simulations of O3 changes from 1979 to 1990 have been carried out. Comparisons with O3 data are presented. Model results suggest that by 1985, significant declines in global O3 were caused by destruction by odd nitrogen associated with long-term variations in the flux of precipitating relativistic electrons (2.6%); solar UV flux changes (1.8%); the dilution effect associated with the Antarctic O3 hole (1.2%); and atmospheric increases in CH4, N2O, and chlorofluorocarbons (0.4%). Analyses of drift-corrected SBUV and Total Ozone Mapping Spectrometer (TOMS) data and model calculations indicate that between 1979 and 1985, reductions of 4.3 to 4.8% in total column O3 averaged between 65-degrees-S and 65-degrees-N have occurred. Calculations indicate a full global O3 decline of 5.2% (peak-to-peak) or 6% (annual average) between 1979 and 1985 with a partial recovery between 1985 and 1989. C1 STX CORP, HAMPTON, VA USA. NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, GREENBELT, MD 20771 USA. AEROSPACE CORP, SPACE SCI LAB, EL SEGUNDO, CA 90245 USA. RP CALLIS, LB (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NR 54 TC 43 Z9 43 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 FEB 20 PY 1991 VL 96 IS D2 BP 2921 EP 2937 DI 10.1029/90JD02171 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA EZ657 UT WOS:A1991EZ65700010 ER PT J AU CALLIS, LB BAKER, DN BLAKE, JB LAMBETH, JD BOUGHNER, RE NATARAJAN, M KLEBESADEL, RW GORNEY, DJ AF CALLIS, LB BAKER, DN BLAKE, JB LAMBETH, JD BOUGHNER, RE NATARAJAN, M KLEBESADEL, RW GORNEY, DJ TI PRECIPITATING RELATIVISTIC ELECTRONS - THEIR LONG-TERM EFFECT ON STRATOSPHERIC ODD NITROGEN LEVELS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SOLAR PROTON EVENTS; MIDDLE ATMOSPHERE; NITRIC-OXIDE; PARTICLE-PRECIPITATION; OZONE PHOTOCHEMISTRY; LIMS OBSERVATIONS; NIMBUS-7 DATA; MESOSPHERE; NO2; TRANSPORT AB Using electron count rate data at geostationary orbit, daily energy spectra, extending from 30 keV to 15 MeV, have been developed for trapped relativistic electrons at 6.6 R(E). These spectra have been used to model the flux of these electrons into the atmosphere at 120 km. Energy deposition calculations permit daily sources of HO(x) and NO(y) to be calculated at auroral and subauroral latitudes due to relativistic electron precipitation (REP) for the period June 13, 1979, through June 4, 1988. Both short-term and long-term source variations are quite large over the period considered. The long-term variation of the NO(y) source is found to reach a maximum in late 1984 and early 1985, with significant declines thereafter. Daily Solar Backscattered Ultraviolet (SBUV) O3 data show a significant response to these precipitation events. Two-dimensional model calculations have been carried out for the period 1979 to 1990 with REP effects included through June 4, 1988. Results suggest that globally integrated NO(y) has increased by 35-40% from 1979 to early 1985 with declines thereafter. The largest long-term increases are found in the lower stratosphere at the high latitudes. Comparisons of Limb Infrared Monitor of the Stratosphere (LIMS), Solar Mesospheric Explorer (SME), Stratospheric Aerosol and Gas Experiment (SAGE), and SAGE II NO2 data are consistent with these calculations. The results suggest that a significant contribution to the anomalously large and unexplained global O3 declines between 1979 and 1985 has been made by the catalytic destruction of O3 by odd nitrogen in the lower stratosphere at mid to high latitudes. The results also provide evidence for a clear and strong linkage between solar variability, the state of the magnetosphere, and the chemical climatological state of the middle and lower atmosphere. C1 ST SYST CORP, HAMPTON, VA USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. AEROSPACE CORP, EL SEGUNDO, CA 90245 USA. UNIV CALIF LOS ALAMOS SCI LAB, LOS ALAMOS, NM 87545 USA. RP CALLIS, LB (reprint author), NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23665 USA. NR 89 TC 79 Z9 80 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 20 PY 1991 VL 96 IS D2 BP 2939 EP 2976 DI 10.1029/90JD02184 PG 38 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA EZ657 UT WOS:A1991EZ65700011 ER PT J AU MCPETERS, RD KOMHYR, WD AF MCPETERS, RD KOMHYR, WD TI LONG-TERM CHANGES IN THE TOTAL OZONE MAPPING SPECTROMETER RELATIVE TO WORLD PRIMARY STANDARD DOBSON SPECTROMETER-83 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article AB We have examined the stability of the calibration of the Nimbus 7 solar backscatter ultraviolet (SBUV) and total ozone mapping spectrometer (TOMS) instruments by comparing their ozone measurements with those made by a single, very stable Dobson instrument: the world primary standard Dobson spectrometer number 83. Measurements of ozone made with instrument 83 at Mauna Loa observatory in eight summers between 1979 and 1989 were compared with coincident TOMS ozone measurements. The comparison shows that relative to instrument 83, ozone measured by TOMS (and SBUV) was stable between 1979 and approximately 1983, had decreased by 3% by 1986, and had decreased by almost 7% by 1989. A similar time dependence is seen when data from an ensemble of 39 Dobson stations throughout the world is compared with TOMS over the period 1979-1987. The most likely reason for the relative drift is that the diffuser plate used by both SBUV and TOMS to measure solar flux has suffered an uncorrected wavelength dependent degradation, with most of the degradation occurring after 1983. The recently released version 6 TOMS data, corrected using the internal "pair justification" technique, show almost no drift relative to Dobson instrument 83. We conclude from these comparisons that accurate measurements of long-term global ozone change will require a coherent system incorporating both ground based and satellite based ozone measurements. C1 NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. RP MCPETERS, RD (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, MAIL CODE 916, GREENBELT, MD 20771 USA. RI McPeters, Richard/G-4955-2013 OI McPeters, Richard/0000-0002-8926-8462 NR 8 TC 40 Z9 40 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 20 PY 1991 VL 96 IS D2 BP 2987 EP 2993 DI 10.1029/90JD02091 PG 7 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA EZ657 UT WOS:A1991EZ65700013 ER PT J AU PICKERING, KE THOMPSON, AM SCALA, JR TAO, WK SIMPSON, J GARSTANG, M AF PICKERING, KE THOMPSON, AM SCALA, JR TAO, WK SIMPSON, J GARSTANG, M TI PHOTOCHEMICAL OZONE PRODUCTION IN TROPICAL SQUALL LINE CONVECTION DURING NASA GLOBAL TROPOSPHERIC EXPERIMENT AMAZON BOUNDARY-LAYER EXPERIMENT-2A SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TRACE-GAS COMPOSITION; DRY SEASON; MARINE TROPOSPHERE; CLOUD TRANSPORT; RAIN-FOREST; WET REMOVAL; BASIN; EMISSION; VARIABILITY; AIR AB We have examined the role of convection in trace gas transport and ozone production in a tropical dry season squall line sampled on August 3, 1985, during NASA Global Tropospheric Experiment/Amazon Boundary Layer Experiment 2A (NASA GTE/ABLE 2A) in Amazonia, Brazil. Two types of analyses were performed. (1) Transient effects within the cloud are examined with a combination of two-dimensional cloud and one-dimensional photochemical modeling. Tracer analyses using the cloud model wind fields yield a series of cross sections of NO(x), CO, and O3 distribution during the lifetime of the cloud; these field are used in the photochemical model to compute the net rate of O3 production. At noon, when the cloud was mature, the instantaneous ozone production potential in the cloud is between 50 and 60% less than in no-cloud conditions due to reduced photolysis and cloud scavenging of radicals. (2) Analysis of cloud inflows and outflows is used to differentiate between air that is undisturbed and air that has been modified by the storm. These profiles are used in the photochemical model to examine the aftereffects of convective redistribution in the 24-hour period following the storm. Total tropospheric column O3 production changed little due to convection because so little NO(x) was available in the lower troposphere. However, the integrated O3 production potential in the 5- to 13-km layer changed from net destruction to net production as a result of the convection. The conditions of the August 3, 1985, event may be typical of the early part of the dry season in Amazonia, when only minimal amounts of pollution from biomass burning have been transported into the region. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. UNIV VIRGINIA, DEPT ENVIRONM SCI, CHARLOTTESVILLE, VA 22903 USA. RP PICKERING, KE (reprint author), APPL RES CORP, 8201 CORP DR, LANDOVER, MD 20785 USA. RI Pickering, Kenneth/E-6274-2012; Thompson, Anne /C-3649-2014 OI Thompson, Anne /0000-0002-7829-0920 NR 41 TC 46 Z9 46 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 20 PY 1991 VL 96 IS D2 BP 3099 EP 3114 DI 10.1029/90JD02284 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA EZ657 UT WOS:A1991EZ65700019 ER PT J AU POLLACK, JB WITTEBORN, FC OBRIEN, K FLYNN, B AF POLLACK, JB WITTEBORN, FC OBRIEN, K FLYNN, B TI A DETERMINATION OF THE INFRARED OPTICAL DEPTH OF THE EL CHICHON VOLCANIC CLOUD SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC AEROSOL SIZE; SULFURIC-ACID; ERUPTION; RADIATION; CONSTANTS; MASS AB Infrared transmission spectra of the atmosphere above 11-km altitude were obtained in December 1982 and April/May 1983 from a NASA Convair 990 aircraft. The observations on the first flight series encompassed low and middle latitudes in the northern hemisphere, while the observations on the second series covered a wide range of latitudes in both hemisphere. We have analyzed these data to derive the optical depth of the El Chichon volcanic cloud at a wavelength of 8.4-mu-m. Comparison of these values with concurrent measurements by Dutton and DeLuisi of the cloud's optical depth at 0.5-mu-m leads to the ratio of the cloud's infrared to visible optical depth, R. We analyzed the observed spectra by rationing pairs of spectra taken at similar latitudes, but different air masses and comparing these ratio spectra with synthetic ones. The synthetic spectra allow for absorption by gases (O3, H2O, CO2, CH4, and N2O) as well as extinction by the cloud particles. Extinction by the cloud particles is particularly important in the 8- to 9-mu-m region. We obtain an average value for R of 0.25 +/- 0.05. Our data imply that concentrated sulfuric acid was the dominant source of aerosol extinction in the 8- to 12-mu-m window region of the Earth's atmosphere and that the volume modal particle radius equalled 0.6 +/- 0.1-mu at the time of our observations. At these times, the volcanic particles produced a significant warming of the lower stratosphere and had a nontrivial impact on the radiation budget of the troposphere and ground in the northern hemisphere. RP POLLACK, JB (reprint author), NASA, AMES RES CTR, DIV SPACE SCI, MOFFETT FIELD, CA 94035 USA. NR 20 TC 10 Z9 10 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 20 PY 1991 VL 96 IS D2 BP 3115 EP 3122 DI 10.1029/90JD02238 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA EZ657 UT WOS:A1991EZ65700020 ER PT J AU HEIRTZLER, JR AF HEIRTZLER, JR TI MAGNETIC-ANOMALIES AND EARLY PLATE-TECTONICS AT LAMONT-DOHERTY-GEOLOGICAL-OBSERVATORY SO TECTONOPHYSICS LA English DT Article; Proceedings Paper CT 9TH ANNUAL SYMP OF THE GEODYNAMICS RESEARCH INST : SILVER ANNIVERSARY CELEBRATION OF PLATE TECTONICS CY APR 22-24, 1987 CL TEXAS A&M UNIV, COLLEGE STN, TX SP GEODYNAM RES INST, NASA, INTER UNION COMMISS LITHOSPHERE, US GEODYNAM COMM HO TEXAS A&M UNIV AB A marine magnetics program was begun at Lamont Geological Observatory in the late 1950's. It consisted of developing the magnetometers, acquiring data from all the oceans, establishing computer processing techniques, and new interpretative methods. Areas off the east coast of North America and over the Reykjanes Ridge showed the linear nature of the magnetic anomalies. The Mid-Atlantic Ridge showed a characteristic anomaly over its entire length. A long magnetic profile obtained in the South Pacific showed that the anomalies were symmetric about the ridge axis and were caused by the same sequence of magnetic bodies as were the anomalies of the Reykjanes Ridge. Similar sequences of anomalies were found in all the oceans and they were best interpreted in terms of the Vine-Matthews-Morley theory of seafloor spreading. The history of the Indian, South Pacific, South Atlantic, and North Atlantic Oceans, the Galapagos, and other areas was published, ushering in the age of plate tectonics. The history of geomagnetic reversals for the last 75 million years was revealed and the age of the sediment layers of the ocean could then be determined with this geomagnetic chronology. These results, which were first made public in 1957, provided much excitement in the scientific community and much interaction among different disciplines. It is here suggested that the rotational motion of the earth could be the ultimate cause of tectonic plate motion, the behavior of the geomagnetic field, variations of climate and the extinction of certain species. A large extraterrestrial impact could perturb all of these phenomena. RP HEIRTZLER, JR (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 29 TC 1 Z9 1 U1 2 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0040-1951 J9 TECTONOPHYSICS JI Tectonophysics PD FEB 20 PY 1991 VL 187 IS 1-3 BP 27 EP 36 DI 10.1016/0040-1951(91)90410-T PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA FC791 UT WOS:A1991FC79100004 ER PT J AU VITTA, S STAN, MA WARNER, JD ALTEROVITZ, SA AF VITTA, S STAN, MA WARNER, JD ALTEROVITZ, SA TI ELECTROMIGRATION FAILURE IN YBA2CU3O7-X THIN-FILMS SO APPLIED PHYSICS LETTERS LA English DT Article AB Electromigration failure in highly oriented YBa2Cu3O7-x thin films below the superconducting transition temperature is reported here for the first time. The film on SrTiO3 failed at 86 K, 2.3 x 10(5) A cm-2; while that on LaAlO3 failed at 84 K, 9.3 x 10(5) A cm-2. Scanning electron microscopy and energy dispersive x-ray analysis of the films after failure shows that Cu migrates preferentially away from the failure region towards the electrode. RP VITTA, S (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Vitta, Satish/K-7336-2015 OI Vitta, Satish/0000-0003-4138-0022 NR 10 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 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD FEB 18 PY 1991 VL 58 IS 7 BP 759 EP 761 DI 10.1063/1.104539 PG 3 WC Physics, Applied SC Physics GA EX595 UT WOS:A1991EX59500033 ER PT J AU BAUSCHLICHER, CW LANGHOFF, SR AF BAUSCHLICHER, CW LANGHOFF, SR TI THEORETICAL-STUDY OF THE C-H BOND-DISSOCIATION ENERGIES OF CH4, C2H2, C2H4, AND H2C2O SO CHEMICAL PHYSICS LETTERS LA English DT Article ID GAUSSIAN BASIS FUNCTIONS; ATOMIC BASIS SETS; FIRST-ROW ATOMS; MOLECULAR CALCULATIONS; CONTRACTION; CI(SD) AB The successive C-H bond dissociation energies of CH4, C2H2, C2H4, and H2C2O (ketene) are determined using large basis sets and a high level of correlation treatment. For CH4, C2H2, and C2H4 the computed values are in excellent agreement with experiment. Using our results we recommend 107.9 +/- 2.0 and 96.7 +/- 2.0 kcal/mol for the C-H bond dissociation energies (D(o) of H2C2 and HC2O, respectively. RP BAUSCHLICHER, CW (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 17 TC 35 Z9 35 U1 2 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 FEB 15 PY 1991 VL 177 IS 2 BP 133 EP 138 DI 10.1016/0009-2614(91)90058-H PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA EY252 UT WOS:A1991EY25200006 ER PT J AU SCHWENKE, DW WALCH, SP TAYLOR, PR AF SCHWENKE, DW WALCH, SP TAYLOR, PR TI A POTENTIAL-ENERGY SURFACE FOR THE PROCESS H2+H2O-]H+H+H2O - ABINITIO CALCULATIONS AND ANALYTICAL REPRESENTATION SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID ELECTRONIC GROUND-STATE; VIBRATIONAL-EXCITATION; WATER MOLECULE; INTENSITIES; CONSTANTS; H2O-16 AB We have performed extensive ab initio calculations on the ground state potential energy surface of H-2 + H2O, using a large contracted Gaussian basis set and a hig level of correlation treatment. An analytical representation of the potential energy surface was then obtained which reproduces the calculated energies with an overall root-mean-square error of only 0.64 mE(h). The analytic representation explicitly includes all nine internal degrees of freedom and is also well behaved as the H-2 dissociates; it thus can be used to study collision-induced dissociation or recombination of H-2. The strategy used to minimiz the number of energy calculations is discussed as well as other advantages of the present method for determining the analytical representation. C1 ELORET INST,PALO ALTO,CA 94303. RP SCHWENKE, DW (reprint author), NASA,AMES RES CTR,MS 230-3,MOFFETT FIELD,CA 94035, USA. RI schwenke, david/I-3564-2013 NR 29 TC 14 Z9 14 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 FEB 15 PY 1991 VL 94 IS 4 BP 2986 EP 2999 DI 10.1063/1.459822 PG 14 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA EY070 UT WOS:A1991EY07000070 ER PT J AU ANDERSON, D HOLLINGSWORTH, A UPPALA, S WOICESHYN, P AF ANDERSON, D HOLLINGSWORTH, A UPPALA, S WOICESHYN, P TI A STUDY OF THE USE OF SCATTEROMETER DATA IN THE EUROPEAN CENTER FOR MEDIUM-RANGE WEATHER FORECASTS OPERATIONAL ANALYSIS-FORECAST MODEL .1. QUALITY ASSURANCE AND VALIDATION SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID A SATELLITE SCATTEROMETER; STATISTICAL STRUCTURE; RADIOSONDE DATA; WIND; ERRORS; SYSTEM; OCEAN; ECMWF AB This paper is Part 1 of a study concerned with the feasibility of using wind scatterometer data in a real-time data assimilation system. The potential that such a system offers for quality assurance and validation of scatterometer data is illustrated using Seasat A satellite scatterometer (SASS) data. The results of passive assimilations of scatterometer data (where the SASS data are passed to the assimilation system but not used), and of active assimilations of scatterometer data (where the data are used), are presented. It is shown that assimilation allows validation and quality assurance of the scatterometer data, through comparisons with collocated ship data and through comparison with the wind fields generated by the assimilation. Intercomparison can be carried out quickly and efficiently at an operational weather centre where large amounts of data are collected, so allowing comprehensive quality assurance and validation of wind scatterometer data to be carried out in near-real-time. A number of comparisons are made which illustrate a speed-dependent bias between SASS and ship observations and between SASS and forecast model, as well as directional irregularities in the SASS data. C1 UNIV OXFORD,CLARENDON LAB,DEPT ATMOSPHER PHYS,OXFORD OX1 3PU,ENGLAND. FINNISH METEOROL INST,SF-00100 HELSINKI 10,FINLAND. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ANDERSON, D (reprint author), EUROPEAN CTR MEDIUM RANGE WEATHER FORECASTS SHINFIELD PK,READING RG2 9AX,BERKS,ENGLAND. NR 17 TC 16 Z9 16 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD FEB 15 PY 1991 VL 96 IS C2 BP 2619 EP 2634 DI 10.1029/90JC02052 PG 16 WC Oceanography SC Oceanography GA EY608 UT WOS:A1991EY60800009 ER PT J AU ANDERSON, D HOLLINGSWORTH, A UPPALA, S WOICESHYN, P AF ANDERSON, D HOLLINGSWORTH, A UPPALA, S WOICESHYN, P TI A STUDY OF THE USE OF SCATTEROMETER DATA IN THE EUROPEAN CENTER FOR MEDIUM-RANGE WEATHER FORECASTS OPERATIONAL ANALYSIS-FORECAST MODEL .2. DATA IMPACT SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID DATA ASSIMILATION; WIND DATA; SEASAT-A; II STORM; PREDICTION; SIMULATIONS; SENSITIVITY; ECMWF AB Data from the Seasat scatterometer are assimilated into the ECMWF analysis-forecast model. To assess the impact of using Seasat A satellite scatterometer (SASS) data, comparison is made between analyses which use this data type and those which do not, as well as between forecasts from these analyses. The differences in the northern hemisphere are found to be small, but sizeable differences occur in the southern hemisphere. Some synoptic comparisons are made between SASS data and the model analyses, as well as data impact on forecasts for the QE-II and Ark Royal storms. C1 UNIV OXFORD,CLARENDON LAB,DEPT ATMOSPHER PHYS,OXFORD OX1 3PU,ENGLAND. FINNISH METEOROL INST,SF-00100 HELSINKI 10,FINLAND. CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ANDERSON, D (reprint author), EUROPEAN CTR MEDIUM RANGE WEATHER FORECASTS,SHINFIELD PK,READING RG2 9AX,BERKS,ENGLAND. NR 21 TC 14 Z9 14 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 FEB 15 PY 1991 VL 96 IS C2 BP 2635 EP 2647 DI 10.1029/90JC02053 PG 13 WC Oceanography SC Oceanography GA EY608 UT WOS:A1991EY60800010 ER PT J AU COMISO, JC WADHAMS, P KRABILL, WB SWIFT, RN CRAWFORD, JP TUCKER, WB AF COMISO, JC WADHAMS, P KRABILL, WB SWIFT, RN CRAWFORD, JP TUCKER, WB TI TOP BOTTOM MULTISENSOR REMOTE-SENSING OF ARCTIC SEA ICE SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID THICKNESS DISTRIBUTION; FRAM STRAIT; MICROWAVE; SUMMER; ZONE AB The Arctic sea ice cover has been studied using near simultaneous observations by passive and active (synthetic aperture radar, SAR) microwave sensors, upward looking and sidescan sonars, a lidar profilometer, and an infrared sensor. Data from two aircraft and a submarine over an approximately 100 km track of central Arctic sea ice were registered and analyzed to evaluate the characteristics of the ice cover and the utility of each sensor in ice studies. The results of comparative and correlation analyses are as follows. The probability density functions of ice draft from sonar and elevation from lidar were found to be almost identical when isostasy is taken into account. This result suggests that the basic ice thickness distribution can be derived from the surface topography measurements alone. Reasonable correlation was found between SAR backscatter and ice draft (or elevation) especially when scales were adjusted such that 15-20 SAR pixels were averaged. However, surface roughness derived directly from standard deviations in the lidar elevation data was found to be poorly correlated to the SAR backscatter. These results indicate that the SAR values are affected more by scattering from the ice than from the snow-covered surface. The active and passive microwave sensors are shown to generally complement each other as the two sensors are especially sensitive to different physical properties of the sea ice. Undeformed first-year ice showed low backscatter values but high brightness temperatures while some multilayer ice showed high backscatter values and low brightness temperature. However, surfaces identified as multiyear ice by the passive system have a large spread in the unaveraged SAR backscatter, indicating limitations when using a one-channel SAR for ice type identification at the highest resolution. Also, ridged ice identified by sonar and SAR data covers a large range of passive microwave emissivity, suggesting considerable variability in the age and salinity of this type of ice. Significant variations (about 0.11) in the minimum emissivity of consolidated multilayer ice are observed in different regions of the Arctic using the high-resolution (30 m) passive microwave data. This suggests that regional variations in texture and scattering characteristics of multiyear ice in the Arctic are present, likely influenced by different histories of formation of the ice in different regions. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NASA,GODDARD SPACE FLIGHT CTR,EG & G WASHINGTON ANALYT,GREENBELT,MD 20771. USA,CORPS ENGINEERS,COLD REG RES & ENGN LAB,HANOVER,NH 03755. UNIV CAMBRIDGE,SCOTT POLAR RES INST,CAMBRIDGE CB2 1ER,ENGLAND. RP COMISO, JC (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,CODE 971,GREENBELT,MD 20771, USA. NR 27 TC 47 Z9 47 U1 0 U2 11 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 FEB 15 PY 1991 VL 96 IS C2 BP 2693 EP 2709 DI 10.1029/90JC02466 PG 17 WC Oceanography SC Oceanography GA EY608 UT WOS:A1991EY60800014 ER PT J AU WANNINKHOF, RH BLIVEN, LF AF WANNINKHOF, RH BLIVEN, LF TI RELATIONSHIP BETWEEN GAS-EXCHANGE, WIND-SPEED, AND RADAR BACKSCATTER IN A LARGE WIND-WAVE TANK SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID AIR-WATER-INTERFACE; CAPILLARY WAVES; SEA; MODEL; SURFACE AB Gas transfer velocities across the air-water interface are correlated with wind speed, friction velocity, and radar backscatter from the surface in a large wind-wave tank in Delft, The Netherlands. The rates of sulfur hexafluoride and nitrous oxide exchange were measured at wind speeds ranging from 3.5 m/s to 20 m/s, and with mechanically generated waves in the 100 m long, 8 m wide, and 0.7 m deep tank. Gas transfer velocities were related to wind speed with a power law dependence. Gas transfer showed a linear dependence with friction velocity. An exponential relationship between gas transfer and average radar backscatter cross section fits the wind tunnel data well for microwave units operating at 13.5 and 35 GHz in VV and HH polarization. The relative rates of gas exchange of the two gases confirm an inverse square root dependence on the Schmidt number at intermediate wind speeds. A slight enhancement of sulfur hexafluoride exchange compared to nitrous oxide exchange was evident when breaking waves were present. C1 NASA,GODDARD SPACE FLIGHT CTR,WALLOPS ISL,VA 23337. COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964. RP WANNINKHOF, RH (reprint author), NOAA,ATLANTIC OCEANOG & METEOROL LABS,DEPT OCEAN CHEM,4301 RICKENBACKER CAUSEWAY,MIAMI,FL 33149, USA. RI bliven, francis/E-1450-2012 NR 40 TC 55 Z9 56 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD FEB 15 PY 1991 VL 96 IS C2 BP 2785 EP 2796 DI 10.1029/90JC02368 PG 12 WC Oceanography SC Oceanography GA EY608 UT WOS:A1991EY60800021 ER PT J AU RAJ, SV AF RAJ, SV TI GRAIN-BOUNDARY SLIDING BEHAVIOR OF COPPER AND ALPHA-BRASS AT INTERMEDIATE TEMPERATURES SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID SIZE DEPENDENCE; CREEP; BICRYSTALS AB The role of grain boundary sliding in copper and Cu-30% Zn in the temperature range 0.50 to 0.72 T(m), where T(m) is the absolute melting point of the material, is examined. First, sliding data obtained on these materials are presented. These results indicate that the stress exponent for sliding, n(gbs), is similar to that for lattice deformation, while the activation energy for sliding, Q(gbs), varies between about 0.5 Q(c) and 1.6 Q(c), where Q(c) is the activation energy for creep. Next, a comparison of the published values of Q(gbs) for bicrystals and polycrystals suggests that grain boundary sliding in polycrystalline materials requires the accommodation of the sliding process, whereas in bicrystals, the absence of triple points and other grain boundaries results in intrinsic sliding. Finally, several models proposed for grain boundary sliding are discussed, and it is shown that they do not account for the observed results on copper and alpha brass. A phenomenological model is proposed, where it is assumed that grain boundary sliding results from the glide of dislocations on secondary slip planes. RP RAJ, SV (reprint author), NASA,LEWIS RES CTR,MS 49-1,21000 BROOKPARK RD,CLEVELAND,OH 44135, USA. NR 38 TC 8 Z9 8 U1 0 U2 4 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0022-2461 J9 J MATER SCI JI J. Mater. Sci. PD FEB 15 PY 1991 VL 26 IS 4 BP 1000 EP 1008 PG 9 WC Materials Science, Multidisciplinary SC Materials Science GA EY759 UT WOS:A1991EY75900020 ER PT J AU SCHUBERT, SD PARK, CK AF SCHUBERT, SD PARK, CK TI LOW-FREQUENCY INTRASEASONAL TROPICAL EXTRATROPICAL INTERACTIONS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID STATIONARY WAVES; TELECONNECTION PATTERNS; GEOPOTENTIAL HEIGHT; NORTHERN HEMISPHERE; EL-NINO; PROPAGATION; VARIABILITY; INSTABILITY; ATMOSPHERE; CONVECTION AB Low-frequency (20-70 day) variability is examined during Northern Hemisphere (NH) winter based on seven years (1981-87) of European Centre for Medium Range Weather Forecasts initialized analyses. The dominant 200 mb zonal wind fluctuations in the Pacific sector, determined from an empirical orthogonal function (EOF) analysis, provide the baseline modes of atmospheric variability, which are related to fluctuations in other circulation parameters and outgoing longwave radiation (OLR). The composite circulation associated with the extreme phases of the zonal wind modes are examined for differences in forcing, wave propagation characteristics and stability. The dominant upper level zonal wind fluctuation (EOF Z1) is associated with an expanded (contracted) region of easterlies in the tropical western Pacific and changes in the shape and intensity of the subtropical jets. The anomalous (difference between composites) eddy streamfunction at 200 mb shows an enhanced pair of anticyclones (cyclones) stradding the equator. These fluctuations are strongly coupled with eastward traveling tropical convection in the western Pacific with a time scale of about 40 days. The composite circulations show marked differences in the propagation of wave activity in the NH at 200 mb. The low phase (reduced easterlies) shows strong propagation away from the dominant source region over East Asia into the tropical western Pacific in conjunction with what appears to be significant reflection from the equatorward flank of the subtropical jet. In contrast, the high composite (enhanced easterlies) shows much weaker equatorward propagation together with reduced vertical propagation over East Asia and the western North Pacific. The second zonal wind EOF (Z2) displays a more asymmetric structure with respect to the equator, describing a simultaneous decrease (increase) in the easterly extent of the East Asian jet and increase (decrease) in the strength of the jet over southern Australia. The anomalous eddy stream function at 200 mb shows wave trains apparently emanating from the tropical central Pacific extending into both hemispheres: in the winter hemisphere this resembles the Pacific-North American (PNA) pattern. These fluctuations show some coupling with preceding tropical convection anomalies in the western and central Pacific. Stability calculations show that the PNA pattern is maintained through barotropic energy exchanges with the mean flow. For the low composite, an enhanced source of stationary wave activity in the Gulf of Alaska is associated with an increase in synoptic-scale eddy activity. These results suggest that tropical convection in the western Pacific has a strong modifying influence on (extratropically forced) middle latitude low-frequency variability. The influence is primarily indirect via zonal wind changes which influence the propagation of waves originating in middle latitudes. The zonal wind changes include those associated with the strength and extent of the tropical easterlies as well as more subtle (but important) changes which effect the curvature of the East Asian jet leading in some instances to turning points for middle latitude waves. The PNA also appears to have its main energy source in middle latitudes and in this case the link with the tropics appears to be more tied to phase locking with anomalies forced by tropical convection in the western and central Pacific. RP SCHUBERT, SD (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 611, GREENBELT, MD 20771 USA. NR 24 TC 48 Z9 48 U1 0 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0022-4928 EI 1520-0469 J9 J ATMOS SCI JI J. Atmos. Sci. PD FEB 15 PY 1991 VL 48 IS 4 BP 629 EP 650 DI 10.1175/1520-0469(1991)048<0629:LFITEI>2.0.CO;2 PG 22 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA FC718 UT WOS:A1991FC71800010 ER PT J AU BARROW, JD COPELAND, EJ KOLB, EW LIDDLE, AR AF BARROW, JD COPELAND, EJ KOLB, EW LIDDLE, AR TI BARYOGENESIS IN EXTENDED INFLATION .1. BARYOGENESIS VIA PRODUCTION AND DECAY OF SUPERMASSIVE BOSONS SO PHYSICAL REVIEW D LA English DT Article ID EARLY UNIVERSE; GRAVITY; STRINGS AB We consider baryogenesis occurring during the thermalization stage at the end of extended inflation. In extended inflation, the Universe passes through a first-order phase transition via bubble nucleation; inflation comes to an end when bubbles collide and their collisions convert energy stored in the bubble walls into particles. This naturally provides conditions well out of thermal equilibrium in which baryon-number-violating processes may proceed; we estimate the amount of baryon asymmetry which may be produced this way. The avoidance of a monopole or domain-wall problem can also be ensured and isothermal density perturbations may arise as a remnant of spatial variation in the baryon asymmetry. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP BARROW, JD (reprint author), UNIV SUSSEX,DIV PHYS & ASTRON,BRIGHTON BN1 9QH,E SUSSEX,ENGLAND. NR 34 TC 21 Z9 21 U1 1 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD FEB 15 PY 1991 VL 43 IS 4 BP 977 EP 983 DI 10.1103/PhysRevD.43.977 PG 7 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA EX994 UT WOS:A1991EX99400003 ER PT J AU BARROW, JD COPELAND, EJ KOLB, EW LIDDLE, AR AF BARROW, JD COPELAND, EJ KOLB, EW LIDDLE, AR TI BARYOGENESIS IN EXTENDED INFLATION .2. BARYOGENESIS VIA PRIMORDIAL BLACK-HOLES SO PHYSICAL REVIEW D LA English DT Article ID 1ST-ORDER PHASE-TRANSITION; PARTICLE EMISSION RATES; EARLY UNIVERSE AB This is the second of two papers devoted to the study of baryogenesis at the end of extended inflation. Extended inflation is brought to an end by the collisions of bubble walls surrounding regions of true vacuum, a process which produces particles well out of thermal equilibrium. In the first paper we considered baryogenesis via direct production and subsequent decay of baryon-number-violating bosons. In this paper we consider the further possibility that the wall collisions may provide a significant density of primordial black holes and examine their possible role in generating a baryon asymmetry. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP BARROW, JD (reprint author), UNIV SUSSEX,DIV PHYS & ASTRON,BRIGHTON BN1 9QH,E SUSSEX,ENGLAND. NR 33 TC 56 Z9 56 U1 1 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD FEB 15 PY 1991 VL 43 IS 4 BP 984 EP 994 DI 10.1103/PhysRevD.43.984 PG 11 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA EX994 UT WOS:A1991EX99400004 ER PT J AU HOLMAN, R KOLB, EW VADAS, SL WANG, Y AF HOLMAN, R KOLB, EW VADAS, SL WANG, Y TI EXTENDED INFLATION FROM HIGHER-DIMENSIONAL THEORIES SO PHYSICAL REVIEW D LA English DT Article ID FALSE VACUUM; UNIVERSE; COMPACTIFICATION; COSMOLOGY; REDUCTION; FLATNESS; DYNAMICS; HORIZON; FATE AB We consider the possibility that higher-dimensional theories may, upon reduction to four dimensions, allow extended inflation to occur. We analyze two separate models. One is a very simple toy model consisting of higher-dimensional gravity coupled to a scalar field whose potential allows for a first-order phase transition. The other is a more sophisticated model incorporating the effects of nontrivial field configurations (monopole, Casimir, and fermion bilinear condensate effects) that yield a nontrivial potential for the radius of the internal space. We find that extended inflation does not occur in these models. We also find that the bubble nucleation rate in these theories is time dependent unlike the case in the original version of extended inflation. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,CHICAGO,IL 60637. UNIV CHICAGO,DEPT PHYS,CHICAGO,IL 60637. RP HOLMAN, R (reprint author), CARNEGIE MELLON UNIV,DEPT PHYS,PITTSBURGH,PA 15213, USA. RI Wang, Yun/B-5724-2011 OI Wang, Yun/0000-0002-4749-2984 NR 31 TC 61 Z9 61 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD FEB 15 PY 1991 VL 43 IS 4 BP 995 EP 1004 DI 10.1103/PhysRevD.43.995 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA EX994 UT WOS:A1991EX99400005 ER PT J AU SALOPEK, DS BOND, JR AF SALOPEK, DS BOND, JR TI STOCHASTIC INFLATION AND NONLINEAR GRAVITY SO PHYSICAL REVIEW D LA English DT Article ID DENSITY PERTURBATIONS; DARK MATTER; UNIVERSE; DYNAMICS AB We show how nonlinear effects of the metric and scalar fields may be included in stochastic inflation. Our formalism can be applied to non-Gaussian fluctuation models for galaxy formation. Fluctuations with wavelengths larger than the horizon length are governed by a network of Langevin equations for the physical fields. Stochastic noise terms arise from quantum fluctuations that are assumed to become classical at horizon crossing and that then contribute to the background. Using Hamilton-Jacobi methods, we solve the Arnowitt-Deser-Misner constraint equations which allows us to separate the growing modes from the decaying ones in the drift phase following each stochastic impulse. We argue that the most reasonable choice of time hypersurfaces for the Langevin system during inflation is T = ln(Ha), where H and a are the local values of the Hubble parameter and the scale factor, since T is the natural time for evolving the short-wavelength scalar field fluctuations in an inhomogenous background. We derive a Fokker-Planck equation which describes how the probability distribution of scalar field values at a given spatial point evolves in T. Analytic Green's-function solutions obtained for a single scalar field self-interacting through an exponential potential are used to demonstrate (1) if the initial condition of the Hubble parameter is chosen to be consistent with microwave-background limits, H(phi-0)/m-rho less-than-or-similar-to 10(-4), then the fluctuations obey Gaussian statistics to a high precision, independent of the time hypersurface choice and operator-ordering ambiguities in the Fokker-Planck equation, and (2) for scales much larger than our present observable patch of the Universe, the distribution is non-Gaussian, with a tail extending to large energy densities; although there are no observable manifestations, it does show eternal inflation. Lattice simulations of our Langevin network for the exponential potential demonstrate how spatial correlations are incorporated. An initially homogeneous and isotropic lattice develops fluctuations as more and more quantum fluctuation modes leave the horizon, yielding Gaussian contour maps for a region corresponding to our observable patch and non-Gaussian contour maps for the ultra-large-scale structure of the Universe. Inflation models with extended non-Gaussian tails at observable scales would lead to a radically different cosmic structure than Gaussian perturbations give. C1 UNIV TORONTO,CANADIAN INST THEORET ASTROPHYS,CANADIAN INST ADV RES PROGRAM,TORONTO M5S 1A1,ONTARIO,CANADA. RP SALOPEK, DS (reprint author), NASA,FERMILAB ASTROPHYS CTR,POB 500 MS-209,BATAVIA,IL 60510, USA. NR 41 TC 155 Z9 155 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 FEB 15 PY 1991 VL 43 IS 4 BP 1005 EP 1031 DI 10.1103/PhysRevD.43.1005 PG 27 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA EX994 UT WOS:A1991EX99400006 ER PT J AU NOTZOLD, D AF NOTZOLD, D TI GRAVITATIONAL EFFECTS OF GLOBAL TEXTURES SO PHYSICAL REVIEW D LA English DT Note AB A solution for the dynamics of global textures is obtained. Their gravitational field during the collapse and the subsequent evolution is found to be given solely by a space-time-dependent "deficit solid angle." The frequency shift of photons traversing this gravitational field is calculated. The observed isotropy of the microwave background constrains the texture symmetry-breaking scale to eta-0 less-than-or-similar-to 1 x 10(16) GeV. The space-time-dependent texture metric locally contracts the volume of three-space and thereby induces overdensities in homogeneous matter distributions. There are no gravitational forces unless matter has a nonzero angular momentum with respect to the texture origin. C1 NASA,FERMILAB ASTROPHYS CTR,FERMI NATL ACCELERATOR LAB,BATAVIA,IL 60510. RP NOTZOLD, D (reprint author), UNIV CHICAGO,CTR ASTRON & ASTROPHYS,CHICAGO,IL 60637, USA. NR 4 TC 22 Z9 22 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 FEB 15 PY 1991 VL 43 IS 4 BP R961 EP R964 DI 10.1103/PhysRevD.43.R961 PG 4 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA EX994 UT WOS:A1991EX99400001 ER PT J AU FARHOOMAND, J MCMURRAY, RE AF FARHOOMAND, J MCMURRAY, RE TI DESIGN PARAMETERS OF A RESONANT INFRARED PHOTOCONDUCTOR WITH UNITY QUANTUM EFFICIENCY SO APPLIED PHYSICS LETTERS LA English DT Article AB A new concept for an infrared photoconductor with enhanced characteristics, such as unity quantum efficiency, high photoconductive gain, and very low noise equivalent power is introduced. The idea revolves around establishing a relatively high finesse absorption-cavity internal to the detector element. A theoretical analysis demonstrates this concept and provides some design guidelines. This concept offers many advantages, especially for low-background astronomy, and may prove to be technologically simpler to implement than other concepts such as the impurity-band-conduction approach. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 8 TC 11 Z9 11 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0003-6951 J9 APPL PHYS LETT JI Appl. Phys. Lett. PD FEB 11 PY 1991 VL 58 IS 6 BP 622 EP 624 DI 10.1063/1.104548 PG 3 WC Physics, Applied SC Physics GA EX187 UT WOS:A1991EX18700025 ER PT J AU JUDAY, RD KUMAR, BVKV RAJAN, PK AF JUDAY, RD KUMAR, BVKV RAJAN, PK TI OPTIMAL REAL CORRELATION FILTERS SO APPLIED OPTICS LA English DT Note AB Expressions are derived for real filters that have a maximum correlation signal to noise ratio. Both continuous and discrete cases are treated and shown to have similar forms. The signal can be complex, and the case of a real signal is considered and related to previous results. C1 CARNEGIE MELLON UNIV,PITTSBURGH,PA 15213. TENNESSEE TECHNOL UNIV,COOKEVILLE,TN 38505. RP JUDAY, RD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 4 TC 10 Z9 10 U1 0 U2 0 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD FEB 10 PY 1991 VL 30 IS 5 BP 520 EP 522 PG 3 WC Optics SC Optics GA EW645 UT WOS:A1991EW64500001 PM 20582021 ER PT J AU BOHLIN, RC CORNETT, RH HILL, JK HILL, RS LANDSMAN, WB OCONNELL, RW NEFF, SG SMITH, AM STECHER, TP AF BOHLIN, RC CORNETT, RH HILL, JK HILL, RS LANDSMAN, WB OCONNELL, RW NEFF, SG SMITH, AM STECHER, TP TI SIMULATED OPTICAL-IMAGES OF GALAXIES AT Z-APPROXIMATELY 1 USING ULTRAVIOLET IMAGES OF NEARBY GALAXIES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMOLOGY; GALAXIES, PHOTOMETRY; GALAXIES, STRUCTURE; ULTRAVIOLET, SPECTRA ID ROCKET ULTRAVIOLET; FAINT GALAXIES; PHOTOMETRY; COLORS; M83 AB Ultraviolet sounding rocket images of several nearby galaxies are used to simulate the appearance in optical bandpasses of similar systems at redshifts z = 0.5-2.67, as observed by the WFPC on HST and by ground-based instruments. Since the morphology of galaxies is a strong function of the wavelength, the appearance of galaxies at large redshifts is subject to a large k-correction effect. The strong dependence of monochromatic surface brightness on redshift [I-lambda approximately (1 + z)-5] also implies that observed morphology of distant systems will be crucially dependent on the limiting surface brightness set by the sky background. Although the angle sub-tended by sources depends only weakly on z, the fraction of a galaxy whose surface brightness is above the detection threshold varies strongly with z. Morphological distinctions of spiral from elliptical, spiral from irregular, and barred from unbarred types become more difficult, as does accurate evaluation of interactions or of the local environment. C1 ST SYST CORP,LANHAM,MD 20706. UNIV VIRGINIA,DEPT ASTRON,CHARLOTTESVILLE,VA 22903. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP BOHLIN, RC (reprint author), SPACE TELESCOPE SCI INST,HOMEWOOD CAMPUS,BALTIMORE,MD 21218, USA. NR 32 TC 26 Z9 26 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 1991 VL 368 IS 1 BP 12 EP 27 DI 10.1086/169666 PN 1 PG 16 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EU508 UT WOS:A1991EU50800002 ER PT J AU PETERSON, BM BALONEK, TJ BARKER, ES BECHTOLD, J BERTRAM, R BOCHKAREV, NG BOLTE, MJ BOND, D BOROSON, TA CARINI, MT CARONE, TE CHRISTENSEN, JA CLEMENTS, SD COCHRAN, AL COHEN, RD CRAMPTON, D DIETRICH, M ELVIS, M FERGUSON, A FILIPPENKO, AV FRICKE, KJ GASKELL, CM HALPERN, JP HUCHRA, JP HUTCHINGS, JB KOLLATSCHNY, W KORATKAR, AP KORISTA, KT KROLIK, JH LAME, NJ LAOR, A LEACOCK, RJ MACALPINE, GM MALKAN, MA MAOZ, D MILLER, HR MORRIS, SL NETZER, H OLIVEIRA, CLM PENFOLD, J PENSTON, MV PEREZ, E POGGE, RW RICHMOND, MW ROMANISHIN, W ROSENBLATT, EI SADDLEMYER, L SADUN, A SAWYER, SR SHIELDS, JC SHAPOVALOVA, AI SMITH, AG SMITH, HA SMITH, PS SUN, WH THIELE, U TURNER, TJ VEILLEUX, S WAGNER, RM WEYMANN, RJ WILKES, BJ WILLS, BJ WILLS, D YOUNGER, PF AF PETERSON, BM BALONEK, TJ BARKER, ES BECHTOLD, J BERTRAM, R BOCHKAREV, NG BOLTE, MJ BOND, D BOROSON, TA CARINI, MT CARONE, TE CHRISTENSEN, JA CLEMENTS, SD COCHRAN, AL COHEN, RD CRAMPTON, D DIETRICH, M ELVIS, M FERGUSON, A FILIPPENKO, AV FRICKE, KJ GASKELL, CM HALPERN, JP HUCHRA, JP HUTCHINGS, JB KOLLATSCHNY, W KORATKAR, AP KORISTA, KT KROLIK, JH LAME, NJ LAOR, A LEACOCK, RJ MACALPINE, GM MALKAN, MA MAOZ, D MILLER, HR MORRIS, SL NETZER, H OLIVEIRA, CLM PENFOLD, J PENSTON, MV PEREZ, E POGGE, RW RICHMOND, MW ROMANISHIN, W ROSENBLATT, EI SADDLEMYER, L SADUN, A SAWYER, SR SHIELDS, JC SHAPOVALOVA, AI SMITH, AG SMITH, HA SMITH, PS SUN, WH THIELE, U TURNER, TJ VEILLEUX, S WAGNER, RM WEYMANN, RJ WILKES, BJ WILLS, BJ WILLS, D YOUNGER, PF TI STEPS TOWARD DETERMINATION OF THE SIZE AND STRUCTURE OF THE BROAD-LINE REGION IN ACTIVE GALACTIC NUCLEI .2. AN INTENSIVE STUDY OF NGC-5548 AT OPTICAL WAVELENGTHS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC 5548); GALAXIES, SEYFERT; SPECTROPHOTOMETRY ID SEYFERT-GALAXIES; STANDARD STARS; VARIABILITY; QUASARS AB We report on a large, international program of ground-based optical spectroscopy and photometry of the variable Seyfert 1 galaxy NGC 5548 undertaken in support of an IUE monitoring campaign described by Clavel and coworkers. In this contribution, we present the data base and describe the methods used to correct for systematic differences between spectra from different sources. Optical continuum and H-beta emission-line continuum is qualitatively the same as the ultraviolet and optical continuum measurements the behavior of the ultraviolet continuum. Cross-correlation of the ultraviolet and optical continuum measurements does not reveal any significant lag between them. The H-beta does not reveal any significant lag between them. The H-beta emission-line variations show the same basic pattern as seen in the continuum and ultraviolet emission lines, with H-beta lagging behind the continuum by approximately 20 days. This is significantly larger than the approximately 10 day lag deduced for Ly-alpha. C1 UNIV CALIF SANTA CRUZ,LICK OBSERV,MT HAMILTON,CA 95140. COLGATE UNIV,HAMILTON,NY 13346. MV LOMONOSOV STATE UNIV,STERNBERG STATE ASTRON INST,MOSCOW 117234,USSR. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. NATL RES COUNCIL CANADA,DOMINION ASTROPHYS OBSERV,OTTAWA K1A 0R6,ONTARIO,CANADA. NATL OPT ASTRON OBSERV,KITT PEAK NATL OBSERV,TUCSON,AZ 85726. UNIV ARIZONA,LUNAR & PLANETARY LAB W,TUCSON,AZ 85721. UNIV FLORIDA,ROSEMARY HILL OBSERV,GAINESVILLE,FL 32611. UNIV STERNWARTE GOTTINGEN,W-3400 GOTTINGEN,GERMANY. UNIV MICHIGAN,DEPT ASTRON,ANN ARBOR,MI 48109. COLUMBIA UNIV,DEPT ASTRON,NEW YORK,NY 10027. JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. TEL AVIV UNIV,SCH PHYS & ASTRON,IL-69978 TEL AVIV,ISRAEL. TEL AVIV UNIV,WISE OBSERV,IL-69978 TEL AVIV,ISRAEL. MT ROYAL COLL,DEPT MATH PHYS & ENGN,CALGARY T3E 6K6,ALBERTA,CANADA. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. ROYAL GREENWICH OBSERV,HAILSHAM BN27 1RP,E SUSSEX,ENGLAND. UNIV OKLAHOMA,DEPT PHYS & ASTRON,NORMAN,OK 73019. INST ASTROFIS CANARIAS,E-38200 LA LAGUNA,SPAIN. ACAD SCI USSR,SPECIAL ASTROPHYS OBSERV,MOSCOW V-71,USSR. AGNES SCOTT COLL,DECATUR,GA 30030. MICHIGAN STATE UNIV,DEPT ASTRON,E LANSING,MI 48824. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NATL CENT UNIV,INST PHYS & ASTRON,CHUNGLI 32054,TAIWAN. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS,GREENBELT,MD 20771. MAX PLANCK INST ASTRON,W-6900 HEIDELBERG,GERMANY. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85724. GEORGIA STATE UNIV,DEPT PHYS & ASTRON,ATLANTA,GA 30303. UNIV CALIF SAN DIEGO,CTR ASTROPHYS & SPACE SCI,LA JOLLA,CA 92093. HARVARD SMITHSONIAN CTR ASTROPHYS,CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. UNIV BRITISH COLUMBIA,DEPT ASTRON,VANCOUVER V6T 1W5,BC,CANADA. RP PETERSON, BM (reprint author), OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210, USA. RI Morris, Simon/G-7981-2011; Mendes de Oliveira, Claudia/F-2391-2012; OI Morris, Simon/0000-0003-4866-110X; Mendes de Oliveira, Claudia/0000-0002-7736-4297; SUN, WEI-HSIN/0000-0002-7474-8658; Gaskell, C/0000-0003-4888-2009; Wilkes, Belinda/0000-0003-1809-2364; Perez, Enrique/0000-0001-9737-4559 NR 15 TC 252 Z9 252 U1 0 U2 6 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 1991 VL 368 IS 1 BP 119 EP 137 DI 10.1086/169675 PN 1 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EU508 UT WOS:A1991EU50800011 ER PT J AU AUMANN, HH PROBST, RG AF AUMANN, HH PROBST, RG TI SEARCH FOR VEGA-LIKE NEARBY STARS WITH 12 MICRON EXCESS SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED; SOURCES; STARS; CIRCUMSTELLAR SHELLS; STARS; EARLY-TYPE ID PICTORIS CIRCUMSTELLAR DISK; BETA-PICTORIS; IRAS AB The identification of Vega-like main-sequence stars with 10-mu-m excess would permit important measurements of the spatial extent of the radiating material with ground-based telescopes. In fact, 55 of the 548 nearby A, F, G, and K dwarfs with IRAS catalog magnitudes at 12-mu-m appear to have excess 12-mu-m flux. However, for only two of these stars, beta Pic and zeta-Lep, was it possible, using small-aperture photometry at 2.2 and 10-mu-m, to verify that the 12-mu-m excess is with high likelihood associated with the star. For the remaining stars the apparent 12-mu-m excess was either traced to IRAS beam confusion or could not be verified at 10-mu-m. The typical 2.2-12-mu-m color of the 106 A, F, G, and K stars in the observing program is only 0.02 mag. Excess flux due to a Vega-like cloud which may surround some of the sources in our observing program, like alpha Lyrae, is thus typically not detectable at 10-mu-m. C1 NATL OPT ASTRON OBSERV,KITT PEAK NATL OBSERV,TUCSON,AZ 85726. RP AUMANN, HH (reprint author), CALTECH,JET PROP LAB,MS 100-22,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 16 TC 68 Z9 68 U1 0 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 10 PY 1991 VL 368 IS 1 BP 264 EP 271 DI 10.1086/169690 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EU508 UT WOS:A1991EU50800026 ER PT J AU SCHENK, PM AF SCHENK, PM TI FLUID VOLCANISM ON MIRANDA AND ARIEL - FLOW MORPHOLOGY AND COMPOSITION SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS LA English DT Article ID ICE VOLCANISM; SATELLITES; RHEOLOGY; LAVA; URANUS; SURFACE; SYSTEM; VISCOSITY; ENCELADUS; VOYAGER-2 AB Several types of volcanic units have been recognized on the icy Uranian satellites Miranda and Ariel. On Miranda, ridges characterized by crest grooves are up to 10 km wide and 500 m high. A continuous flat-topped flow band also 10 km wide and 500 m high forms the outer southern margin of Elsinore Corona. Elsinore Coronae at least appears to comprise coalesced flow bands and ridges. On Ariel, in addition to at least one ridge unit similar to thse on Miranda, flood plains material has covered the floors of deep chasmata (grabens) and an irregular depression. Flows on both satellites are characterized by linear vent geometries and distinct topographic margins, which indicate extrusion of a relatively viscous material. The topography of the flows can be used to estimate flow viscosity or yield strength using a Bingham plastic model. Extrusion viscosity estimates, incorporating plausible volcanologically based emplacement time scales and a rigid crust correction, range from 10(7) to 10(9) P (10(13) P in the unlikely absence of a chilled crust). Viscosity estimates are dependent on the assumed emplacement time scale, however, and could be as high as 10(16) P, if a solid-state-based time scale is assumed. Bingham models indicate that it is yield strength that controls the final flow width and thickness that we see. Yield strength estimates are probably more reliable because of uncertainties in the viscous flow time scale. Yield strength estimates range from 10(-1) to 10(-2) bars, consistent with yield strengths of partially crystallized silicate melts on other planets. Nevertheless, both the viscosities and yield strengths are well within the range of (and in some cases lower than) silicate flows. Silicate compositions are not possible for these flows because of the ice-rich composition of these satellites. Measured properties of ammonia-water liquid-crystal mixtures are consistent with the observed and estimated flow rheologic properties, however, and extrusion of such material(s) is a viable alternative to solid-state extrusion for the origin of these flow features. RP SCHENK, PM (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109, USA. NR 78 TC 37 Z9 37 U1 1 U2 7 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-SOLID PD FEB 10 PY 1991 VL 96 IS B2 BP 1887 EP 1906 DI 10.1029/90JB01604 PG 20 WC Geosciences, Multidisciplinary SC Geology GA EX668 UT WOS:A1991EX66800001 ER PT J AU SCHNEEBERGER, DM PIERI, DC AF SCHNEEBERGER, DM PIERI, DC TI GEOMORPHOLOGY AND STRATIGRAPHY OF ALBA PATERA, MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS LA English DT Article ID MARTIAN SURFACE; LAVA FLOWS; MORPHOLOGY; SEQUENCE AB Geomorphic and stratigraphic analysis of Alba Patera suggests a volcanic construct built by lavas with rheologic properties similar to basalts. A series of evolving eruptive styles is suggested by changes in morphology and inferred progressive reductions in flow volume with higher stratigraphic position. Alba Patera's volcanic history has been summarized into four main phases. The first is characterized by extensive flood like flows presumably erupted from fissures associated with the initial intrusion of magma into the region. The second phase is associated with the emplacement of pyroclastic rock, a more speculative interpretation. The third phase produced the voluminous tabular, crested, and undifferentiated flows, probably from a more centralized vent source. The fourth and last phase is marked the effusion of levee like flows and the collapse of the summit calderas and final graben formation. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP SCHNEEBERGER, DM (reprint author), SNR CO,LAGUNA HILLS,CA, USA. NR 39 TC 17 Z9 17 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-SOLID PD FEB 10 PY 1991 VL 96 IS B2 BP 1907 EP 1930 DI 10.1029/90JB01662 PG 24 WC Geosciences, Multidisciplinary SC Geology GA EX668 UT WOS:A1991EX66800002 ER PT J AU DIXON, TH GONZALEZ, G LICHTEN, SM KATSIGRIS, E AF DIXON, TH GONZALEZ, G LICHTEN, SM KATSIGRIS, E TI 1ST EPOCH GEODETIC MEASUREMENTS WITH THE GLOBAL POSITIONING SYSTEM ACROSS THE NORTHERN CARIBBEAN PLATE BOUNDARY ZONE SO JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS LA English DT Article ID LONG BASELINE INTERFEROMETRY; PHASE AMBIGUITY RESOLUTION; CRUSTAL DEFORMATION; RELATIVE MOTION; SOUTH-AMERICA; WATER-VAPOR; PATH-DELAY; PRECISION; TECTONICS; CALIFORNIA AB The first geodetic survey across the northern Caribbean plate boundary zone with the Global Positioning System (GPS) was conducted in June 1986. Baseline vectors defined by the six station regional GPS network ranged from 170 to 1260 km in length. Repeatability of independent daily baseline estimates was better than 8 mm plus 1.3 parts in 10(8) of baseline length for horizontal components. The wet tropospheric path delay during the experiment was both high, sometimes exceeding 30 cm at zenith, and variable, sometimes exceeding 5 cm variation over several hours. Successful carrier phase cycle ambiguity resolution ("bias fixing") could not be achieved prior to construction of a regional troposphere model. Tropospheric calibration was achieved with water vapor radiometers at selected sites, and with stochastic troposphere models and estimation techniques at remaining sites. With optimum troposphere treatment and single-day orbital arcs we resolved most biases in the network regardless of baseline length. Our results suggest that constraints on plate boundary zone deformation in the Greater Antilles, and on the North America-Caribbean relative plate motion vector, can be obtained with a series of GPS experiments spanning less than 10 and 15 years, respectively. RP CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. NR 52 TC 24 Z9 27 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SOLID PD FEB 10 PY 1991 VL 96 IS B2 BP 2397 EP 2415 DI 10.1029/90JB02003 PG 19 WC Geosciences, Multidisciplinary SC Geology GA EX668 UT WOS:A1991EX66800032 ER PT J AU YUAN, T WANG, C YU, CL FRENKLACH, M RABINOWITZ, MJ AF YUAN, T WANG, C YU, CL FRENKLACH, M RABINOWITZ, MJ TI DETERMINATION OF THE RATE COEFFICIENT FOR THE REACTION H+O2-]OH+O BY A SHOCK-TUBE LASER-ABSORPTION DETAILED MODELING STUDY SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID HEATED H2-O2-AR MIXTURES; RESONANCE-ABSORPTION; RATE-CONSTANT; HYDROGEN-AIR; O-ATOMS; SPECTROSCOPY; O+H2->OH+H; COMBUSTION; IGNITION; BAND AB Mixtures of hydrogen and oxygen diluted in argon were studied behind reflected shock waves at temperatures from 1050 to 2700 K. The reaction progress was measured in situ by state-selective laser absorption of OH radicals. Solution mapping methodology was employed to interpret the experimental results, quantifying the effects of all active rate parameters. The rate coefficient expression for the key reaction in the system, H + O2 --> OH + O, derived was k1 = 1.59 X 10(-17)T-0.927-e-8493/T cm3 mol-1 s-1 with one standard deviation of 0.05 for log k1. The analysis indicates that under no physically realistic conditions could the values of k1 reach those reported by Frank and Just (1985), and that in most cases the k1 temperature-dependent expression is close to the results of Schott (1973). C1 PENN STATE UNIV,DEPT MAT SCI & ENGN,FUEL SCI PROGRAM,UNIVERSITY PK,PA 16802. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 49 TC 59 Z9 59 U1 0 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD FEB 7 PY 1991 VL 95 IS 3 BP 1258 EP 1265 DI 10.1021/j100156a041 PG 8 WC Chemistry, Physical SC Chemistry GA EW478 UT WOS:A1991EW47800041 ER PT J AU HANSEN, JE LACIS, AA AF HANSEN, JE LACIS, AA TI SUN AND WATER IN THE GREENHOUSE - REPLY SO NATURE LA English DT Letter ID SOLAR LUMINOSITY; SECULAR PERTURBATIONS; CONVECTIVE ENVELOPE RP HANSEN, JE (reprint author), NASA,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Lacis, Andrew/D-4658-2012 NR 13 TC 2 Z9 2 U1 0 U2 0 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD FEB 7 PY 1991 VL 349 IS 6309 BP 467 EP 467 DI 10.1038/349467c0 PG 1 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA EW571 UT WOS:A1991EW57100037 ER PT J AU RIND, D CHIOU, EW CHU, W LARSEN, J OLTMANS, S LERNER, J MCCORMICK, MP MCMASTER, L AF RIND, D CHIOU, EW CHU, W LARSEN, J OLTMANS, S LERNER, J MCCORMICK, MP MCMASTER, L TI POSITIVE WATER-VAPOR FEEDBACK IN CLIMATE MODELS CONFIRMED BY SATELLITE DATA SO NATURE LA English DT Article AB CHIEF among the mechanisms thought to amplify the global climate response to increased concentrations of trace gases is the atmospheric water vapour feedback. As the oceans and atmosphere warm, there is increased evaporation, and it has been generally thought that the additional moisture then adds to the greenhouse effect by trapping more infrared radiation. Recently, it has been suggested that general circulation models used for evaluating climate change overestimate this response, and that increased convection in a warmer climate would actually dry the middle and upper troposphere by means of associated compensatory subsidence1. We use some new satellite-generated water vapour data to investigate this question. From a comparison of summer and winter moisture values in regions of the middle and upper troposphere that have previously been difficult to observe with confidence, we find that, as the hemispheres warm, increased convection leads to increased water vapour above 500 mbar in approximate quantitative agreement with the results from current climate models. The same conclusion is reached by comparing the tropical western and eastern Pacific regions. Thus, we conclude that the water vapour feedback is not overestimated in models and should amplify the climate response to increased trace-gas concentrations. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NOAA,CMDL,BOULDER,CO 80302. RP RIND, D (reprint author), NASA,GODDARD INST SPACE STUDIES,NEW YORK,NY 10025, USA. NR 10 TC 151 Z9 151 U1 0 U2 9 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD FEB 7 PY 1991 VL 349 IS 6309 BP 500 EP 503 DI 10.1038/349500a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA EW571 UT WOS:A1991EW57100057 ER PT J AU HSU, MTS CHEN, TS RICCITIELLO, SR AF HSU, MTS CHEN, TS RICCITIELLO, SR TI PRECERAMIC ORGANOBORON-SILICON POLYMERS SO JOURNAL OF APPLIED POLYMER SCIENCE LA English DT Article ID POLYCARBOSILANE; PRECURSORS; CERAMICS; CARBIDE AB Several boron-containing organosilicon polymers were synthesized from a sodium-coupling reaction of silicon and boron halides with and without alkyl halide in hydrocarbon solvents. The B-Si preceramic polymers were characterized using techniques such as IR, UV, and NMR spectrometry, gel permeation chromatography, elemental analysis, molecular weight measurement, and thermal analyses (TGA, DSC, DTA, and TMA). The chemical structures of the preceramic polymers were postulated based on the analytical results. Black ceramic materials were obtained from the precursor polymers upon thermal degradation at temperatures above 1000-degrees-C in an inert atmosphere. The precursor polymers had a ceramic yield of up to 70%. Thermogravimetric analysis of the ceramic material in air at a flow rate of 100 mL/min showed it was stable up to 1000-degrees-C with little weight gain or loss. Several methods were used to characterize the ceramic materials: XRD, solid NMR, high-temperature DTA, elemental analysis, and acid digestion. The analyses indicated that the ceramic materials comprised a mixture of silicon carbide (SiC), silicon borides (SiB4, SiB6), and amorphous Si-B-C ceramics, with small amounts of silica and free silicon. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. HC CHEM RES & SERV CORP,SAN JOSE,CA 95133. NR 15 TC 28 Z9 29 U1 2 U2 13 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0021-8995 J9 J APPL POLYM SCI JI J. Appl. Polym. Sci. PD FEB 5 PY 1991 VL 42 IS 3 BP 851 EP 861 DI 10.1002/app.1991.070420331 PG 11 WC Polymer Science SC Polymer Science GA ET467 UT WOS:A1991ET46700031 ER PT J AU STRANGE, M AF STRANGE, M TI BUFFERS STABILIZE OSCILLATOR SO EDN LA English DT Note RP STRANGE, M (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU CAHNERS-DENVER PUBLISHING CO PI HIGHLANDS RANCH PA 8773 S RIDGELINE BLVD, HIGHLANDS RANCH, CO 80126-2329 SN 0012-7515 J9 EDN JI EDN PD FEB 4 PY 1991 VL 36 IS 3 BP 105 EP 105 PG 1 WC Engineering, Electrical & Electronic SC Engineering GA EW003 UT WOS:A1991EW00300010 ER PT J AU BERATAN, KK NIELSON, JE AF BERATAN, KK NIELSON, JE TI THE COLORADO RIVER EXTENSIONAL CORRIDOR - AN ANALOG FOR THE EARLY STAGES OF PASSIVE MARGIN FORMATION SO AAPG BULLETIN-AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS LA English DT Meeting Abstract C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. US GEOL SURVEY,MENLO PK,CA 94025. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSN PETROL GEOLOGISTS PI TULSA PA 1444 S BOULDER AVE PO BOX 979, TULSA, OK 74101 SN 0149-1423 J9 AAPG BULL JI AAPG Bull.-Am. Assoc. Petr. Geol. PD FEB PY 1991 VL 75 IS 2 BP 356 EP 356 PG 1 WC Geosciences, Multidisciplinary SC Geology GA EZ450 UT WOS:A1991EZ45000021 ER PT J AU ROUSE, DJ WINFIELD, DL CANADA, SC AF ROUSE, DJ WINFIELD, DL CANADA, SC TI NASA SPINOFFS TO BIOENGINEERING AND MEDICINE SO ACTA ASTRONAUTICA LA English DT Article AB Through the active transfer of technology, the National Aeronautics and Space Administration (NASA) Technology Utilization (TU) Program assists private companies, associations, and government agencies to make effective use of NASA's technological resources to improve U.S. economic competitiveness and to provide societal benefit. Aerospace technology from areas such as digital image processing, space medicine and biology, microelectronics, optics and electrooptics, and ultrasonic imaging have found many secondary applications in medicine. Examples of technology spinoffs are briefly discussed to illustrate the benefits realized through adaptation of aerospace technology to solve health care problems. Successful implementation of new technologies increasingly requires the collaboration of industry, universities, and government, and the TU Program serves as the liaison to establish such collaborations with NASA. NASA technology is an important resource to support the development of new medical products and techniques that will further advance the quality of health care available in the U.S. and worldwide. RP ROUSE, DJ (reprint author), NASA TECHNOL APPLICAT TEAM,RES TRIANGLE INST,POB 12194,RES TRIANGLE PK,NC 27709, USA. NR 0 TC 0 Z9 0 U1 1 U2 7 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 FEB PY 1991 VL 25 IS 2 BP 103 EP 110 DI 10.1016/0094-5765(91)90067-F PG 8 WC Engineering, Aerospace SC Engineering GA FN397 UT WOS:A1991FN39700007 PM 11540738 ER PT J AU MEADOWS, KR KUMAR, A HUSSAINI, MY AF MEADOWS, KR KUMAR, A HUSSAINI, MY TI COMPUTATIONAL STUDY ON THE INTERACTION BETWEEN A VORTEX AND A SHOCK-WAVE SO AIAA JOURNAL LA English DT Article AB A computational study of two-dimensional shock vortex interaction is discussed in this paper. A second-order upwind finite volume method is used to solve the Euler equations in conservation form. In this method, the shock wave is captured rather than fitted so that the cases where shock vortex interaction may cause secondary shocks can also be investigated. The effects of vortex strength on the computed flow and acoustic field generated by the interaction are qualitatively evaluated. C1 NASA,LANGLEY RES CTR,INST COMP APPL SCI & ENGN,HAMPTON,VA 23665. RP MEADOWS, KR (reprint author), NASA,LANGLEY RES CTR,COMPUTAT METHODS BRANCH,HAMPTON,VA 23665, USA. NR 20 TC 38 Z9 38 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 FEB PY 1991 VL 29 IS 2 BP 174 EP 179 DI 10.2514/3.59916 PG 6 WC Engineering, Aerospace SC Engineering GA FA441 UT WOS:A1991FA44100003 ER PT J AU SHIRINZADEH, B HILLARD, ME EXTON, RJ AF SHIRINZADEH, B HILLARD, ME EXTON, RJ TI CONDENSATION EFFECTS ON RAYLEIGH-SCATTERING MEASUREMENTS IN A SUPERSONIC WIND-TUNNEL SO AIAA JOURNAL LA English DT Article ID HOMOGENEOUS NUCLEATION; GAS CONCENTRATION AB Rayleigh and Raman scattering measurements have been performed in the 20-in., Mach 6 wind tunnel at the NASA Langley Research Center. Rayleigh results show signal levels much higher than expected for molecular scattering in the tunnel, whereas densities deduced from spontaneous Raman scattering of molecular nitrogen are in good agreement with the expected nitrogen densities in the facility. The apparent discrepancy in the Rayleigh result is attributed to cluster formation as a result of expansion in the tunnel. The dependence of the Rayleigh signal on the stagnation pressure and temperature is also discussed. RP SHIRINZADEH, B (reprint author), NASA,LANGLEY RES CTR,DIV INSTRUMENT RES,OPT SPECT SECT,HAMPTON,VA 23665, USA. NR 10 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 FEB PY 1991 VL 29 IS 2 BP 242 EP 246 DI 10.2514/3.10570 PG 5 WC Engineering, Aerospace SC Engineering GA FA441 UT WOS:A1991FA44100011 ER PT J AU SOBIESZCZANSKISOBIESKI, J BLOEBAUM, CL HAJELA, P AF SOBIESZCZANSKISOBIESKI, J BLOEBAUM, CL HAJELA, P TI SENSITIVITY OF CONTROL-AUGMENTED STRUCTURE OBTAINED BY A SYSTEM DECOMPOSITION METHOD SO AIAA JOURNAL LA English DT Article AB The paper presents the verification of a new method for computing behavior sensitivities of a coupled system. The method deals with a system whose analysis can be partitioned into subsets that correspond to disciplines and/or physical subsystems that exchange input-output data with each other. The method uses the partial derivatives of the output with respect to input obtained for each subset separately to assemble a set of linear simultaneous algebraic equations that are solved for the total derivatives of the coupled system response. This sensitivity analysis is verified using an example of a cantilever beam augmented with an active control system to limit the beam's dynamic displacements under an excitation force. The verification shows good agreement of the method with reference data obtained by a finite difference technique involving entire system analysis. The paper also demonstrates the usefulness of a new system sensitivity method in optimization applications by employing a piecewise-linear approach to the same numerical example. The new method's principal merits are its intrinsically superior accuracy in comparison with the finite difference technique, and its compatibility with the traditional division of work in complex engineering tasks among specialty groups. C1 UNIV FLORIDA,GAINESVILLE,FL 32611. RP SOBIESZCZANSKISOBIESKI, J (reprint author), NASA,LANGLEY RES CTR,INTERDISCIPLINARY RES OFF,HAMPTON,VA 23665, USA. NR 8 TC 22 Z9 22 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 FEB PY 1991 VL 29 IS 2 BP 264 EP 270 DI 10.2514/3.10573 PG 7 WC Engineering, Aerospace SC Engineering GA FA441 UT WOS:A1991FA44100014 ER PT J AU GRAY, CE MEI, C SHORE, CP AF GRAY, CE MEI, C SHORE, CP TI FINITE-ELEMENT METHOD FOR LARGE-AMPLITUDE 2-DIMENSIONAL PANEL FLUTTER AT HYPERSONIC SPEEDS SO AIAA JOURNAL LA English DT Article AB A finite element approach is presented for determining the nonlinear flutter characteristics of two-dimensional panels using unsteady, third-order piston theory aerodynamics. Both nonlinear (large-amplitude) structural and nonlinear aerodynamic terms are considered in the finite element formulation. Solution procedures are presented to solve the nonlinear panel flutter and large-amplitude free vibration finite element equations. Nonlinear flutter analyses are performed for different boundary-support conditions and for various system parameters: plate thickness to length ratio h/a; Mach number M; flow-mass density to panel-mass density ratio; dynamic pressure lambda; and maximum deflection to thickness ratio c/h. For large-amplitude free vibration, alternative classical analytical solutions are available for comparison. Linear aerodynamic and nonlinear structural finite element flutter results are compared with existing classical solutions, and nonlinear (aerodynamic and structure) results are compared among finite element findings presented in this study to assess the influence of including the nonlinearities associated with the third-order piston theory aerodynamics. In addition, the effect of varying the support conditions on the limit-cycle dynamic pressure is also evaluated. C1 OLD DOMINION UNIV,DEPT MECH ENGN & MECH,NORFOLK,VA 23529. RP GRAY, CE (reprint author), NASA,LANGLEY RES CTR,DIV FACIL ENGN,HAMPTON,VA 23665, USA. NR 29 TC 21 Z9 33 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 FEB PY 1991 VL 29 IS 2 BP 290 EP 298 DI 10.2514/3.10576 PG 9 WC Engineering, Aerospace SC Engineering GA FA441 UT WOS:A1991FA44100017 ER PT J AU FUNG, KY CARR, LW AF FUNG, KY CARR, LW TI EFFECTS OF COMPRESSIBILITY ON DYNAMIC STALL SO AIAA JOURNAL LA English DT Note C1 NASA,AMES RES CTR,USA,AEROFLIGHTDYNAM DIRECTORATE,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,FLUID DYNAM RES BRANCH,MOFFETT FIELD,CA 94035. RP FUNG, KY (reprint author), UNIV ARIZONA,DEPT AEROSP & MECH ENGN,TUCSON,AZ 85721, USA. NR 13 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 0001-1452 J9 AIAA J JI AIAA J. PD FEB PY 1991 VL 29 IS 2 BP 306 EP 308 DI 10.2514/3.10578 PG 3 WC Engineering, Aerospace SC Engineering GA FA441 UT WOS:A1991FA44100019 ER PT J AU NEMETH, MP AF NEMETH, MP TI BUCKLING AND POSTBUCKLING BEHAVIOR OF COMPRESSION-LOADED ISOTROPIC PLATES WITH CUTOUTS SO AIAA JOURNAL LA English DT Note ID PERFORATED PLATES RP NEMETH, MP (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT MECH,AIRCRAFT STRUCT BRANCH,HAMPTON,VA 23665, USA. NR 12 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 0001-1452 J9 AIAA J JI AIAA J. PD FEB PY 1991 VL 29 IS 2 BP 313 EP 314 DI 10.2514/3.10581 PG 2 WC Engineering, Aerospace SC Engineering GA FA441 UT WOS:A1991FA44100022 ER PT J AU CONVERTINO, VA MACK, GW NADEL, ER AF CONVERTINO, VA MACK, GW NADEL, ER TI ELEVATED CENTRAL VENOUS-PRESSURE - A CONSEQUENCE OF EXERCISE TRAINING-INDUCED HYPERVOLEMIA SO AMERICAN JOURNAL OF PHYSIOLOGY LA English DT Article DE ARTERIAL PRESSURE; BLOOD VOLUME; VENOUS CAPACITANCE; VENOUS COMPLIANCE; ATRIAL NATRIURETIC PEPTIDE; VASOPRESSIN; ALDOSTERONE; NOREPINEPHRINE ID BLOOD-VOLUME; HEART-RATE; RESPONSES; HUMANS; VASOPRESSIN; IMMERSION AB Resting blood volumes and arterial and central venous pressures (CVP) were measured in 14 men before and after exercise training to determine whether training-induced hypervolemia is accompanied by a change in total vascular capacitance. In addition, resting levels of plasma arginine vasopressin (AVP), atrial natriuretic peptide (ANP), aldosterone (Ald), and norepinephrine (NE) were measured. The same measurements were conducted in seven subjects who did not undergo exercise and acted as controls. Exercise training consisted of 10 wk of controlled cycle exercise for 30 min/day, 4 days/wk at 75-80% of maximal O2 uptake (VO2 max). A training effect was verified by a 20% increase in VO2 max, a resting bradycardia, and a 9% increase in blood volume. Mean arterial blood pressure was unaltered by exercise training, but resting CVP increased by 16% (P < 0.05). The percent change in blood volume from before to after training was linearly related to the percent change in CVP (r = 0.903, P < 0.05). As a consequence of elevations in both blood volume and CVP, the volume-to-pressure ratio was unchanged after exercise training. Plasma AVP, ANP, Ald, and NE were unaltered. Our results indicate that elevated CVP is a consequence of training-induced hypervolemia without alteration in total effective venous capacitance. C1 NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899. JOHN B PIERCE FDN LAB,NEW HAVEN,CT 06519. NR 25 TC 45 Z9 45 U1 1 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 FEB PY 1991 VL 260 IS 2 BP R273 EP R277 PN 2 PG 5 WC Physiology SC Physiology GA EY856 UT WOS:A1991EY85600046 PM 1996713 ER PT J AU CANFIELD, DE AF CANFIELD, DE TI SULFATE REDUCTION IN DEEP-SEA SEDIMENTS SO AMERICAN JOURNAL OF SCIENCE LA English DT Article ID ORGANIC-MATTER; MARINE-SEDIMENTS; CARBON; MINERALIZATION; PRODUCTIVITY; DIAGENESIS AB Sulfate reduction rates calculated from about 200 DSDP pore water sulfate profiles have been contoured and plotted on a map covering most areas of the world ocean. Rates show a remarkable spatial consistency, with high rates observed near the continental margins, becoming progressively lower toward the central ocean basins. Relatively elevated rates are also found in the eastern equatorial Pacific, a site of upwelling and correspondingly high rates of primary organic production. Overall, the distribution of sulfate reduction in pelagic sediments looks very similar to the distribution of primary organic carbon production. When rates are directly compared, however, the correlation between sulfate reduction and primary production is only moderately strong. Perhaps the most important influence on sulfate reduction is sediment deposition rate and the control this has over the fraction of the sedimentary organic carbon flux that becomes available for sulfate reduction. The slower the rate of sediment deposition the more time for oxic respiration and the less organic carbon that escapes to the zone of sulfate reduction. To predict most accurately sulfate reduction rates, however, the variables of primary production, water depth, and sediment deposition rate must all be integrated. RP CANFIELD, DE (reprint author), NASA,AMES RES CTR,MS239-4,MOFFETT FIELD,CA 94035, USA. RI Canfield, Don/C-1735-2012 OI Canfield, Don/0000-0001-7602-8366 FU NCIPC CDC HHS [OCE 8508472] NR 33 TC 98 Z9 108 U1 0 U2 17 PU KLINE GEOLOGY LABORATORY PI NEW HAVEN PA YALE UNIV, NEW HAVEN, CT 06520 SN 0002-9599 J9 AM J SCI JI Am. J. Sci. PD FEB PY 1991 VL 291 IS 2 BP 177 EP 188 PG 12 WC Geosciences, Multidisciplinary SC Geology GA EV486 UT WOS:A1991EV48600002 PM 11538491 ER PT J AU TSAO, NK AF TSAO, NK TI ON THE ACCURACY OF SOLVING TRIANGULAR SYSTEMS IN PARALLEL SO APPLIED NUMERICAL MATHEMATICS LA English DT Article AB In this paper a component-wise detailed error analysis of two algorithms for solving unidiagonal triangular systems is given. The results show that the parallel algorithm as proposed by Sameh and Brent [1] is essentially equivalent to the usual sequential algorithm as far as round-off error is concerned, contrasting their earlier pessimistic results about the error bounds. C1 NASA,LEWIS RES CTR,ICOMP,CLEVELAND,OH 44135. RP TSAO, NK (reprint author), WAYNE STATE UNIV,DEPT COMP SCI,DETROIT,MI 48202, USA. NR 2 TC 3 Z9 3 U1 0 U2 0 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 FEB PY 1991 VL 7 IS 2 BP 207 EP 215 DI 10.1016/0168-9274(91)90064-7 PG 9 WC Mathematics, Applied SC Mathematics GA EX980 UT WOS:A1991EX98000006 ER PT J AU NORTON, RH RINSLAND, CP AF NORTON, RH RINSLAND, CP TI ATMOS DATA-PROCESSING AND SCIENCE ANALYSIS-METHODS SO APPLIED OPTICS LA English DT Article ID SOLAR OCCULTATION SPECTRA; INFRARED SPECTROSCOPIC MEASUREMENTS; FOURIER-TRANSFORM SPECTROSCOPY; DOPPLER-LIMITED SPECTRUM; DIODE-LASER SPECTROSCOPY; LOWER STRATOSPHERE; LINE POSITIONS; UPPER TROPOSPHERE; ABSORPTION-SPECTRA; CARBONYL FLUORIDE AB The ATMOS (atmospheric trace molecule spectroscopy) instrument, a high speed Fourier transform spectrometer operating in the middle IR (2.2-16-mu-m), recorded more than 1500 solar spectra at approximately 0.0105-cm-1 resolution during its first mission onboard the shuttle Challenger in the spring of 1985. These spectra were acquired during high sun conditions for studies of the solar atmosphere and during low sun conditions for studies of the earth's upper atmosphere. This paper describes the steps by which the telemetry data were converted into spectra suitable for analysis, the analysis software and methods developed for the atmospheric and solar studies, and the ATMOS data analysis facility. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665. RP NORTON, RH (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 89 TC 86 Z9 91 U1 1 U2 8 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD FEB 1 PY 1991 VL 30 IS 4 BP 389 EP 400 PG 12 WC Optics SC Optics GA EW644 UT WOS:A1991EW64400014 PM 20582004 ER PT J AU EGAN, WG JOHNSON, WR WHITEHEAD, VS AF EGAN, WG JOHNSON, WR WHITEHEAD, VS TI TERRESTRIAL POLARIZATION IMAGERY OBTAINED FROM THE SPACE-SHUTTLE - CHARACTERIZATION AND INTERPRETATION SO APPLIED OPTICS LA English DT Article ID ATMOSPHERIC OPTICAL-PROPERTIES; PLANETARY ATMOSPHERES; METEOROLOGICAL VARIATION; LIGHT-SCATTERING; ANTARCTIC STORM; EL-CHICHON; RADIATION; WATER; CLOUD; OCEAN AB An experiment to measure the polarization of land, sea, haze, and cloud areas from space was carried aboard the Space Shuttle in Sept. 1985. Digitized polarimetric and photometric imagery in mutually perpendicular planes was derived in the red, green, and blue spectral regions from photographs taken with two synchronized Hasselblad cameras using type 5036 Ektachrome film. Digitization at the NASA Houston Video Digital Analysis Systems Laboratory permitted reduction of the imagery into equipolarimetric contours with a relative accuracy of +/- 20% for comparison to ground truth. The Island of Hawaii and adjacent sea and cloud areas were the objects of the specific imagery analyzed. Results show that cloud development is uniquely characterized using percent polarization without requiring precision photometric calibration. Furthermore, sea state and wind direction over the sea could be inferred as well as terrestrial soil texture. C1 COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77258. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 37 TC 49 Z9 51 U1 1 U2 5 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0003-6935 J9 APPL OPTICS JI Appl. Optics PD FEB 1 PY 1991 VL 30 IS 4 BP 435 EP 442 PG 8 WC Optics SC Optics GA EW644 UT WOS:A1991EW64400021 PM 20582011 ER PT J AU SMITH, EP HINTZEN, P AF SMITH, EP HINTZEN, P TI THE GALAXY ACTIVITY-INTERACTION CONNECTION .1. OPTICAL OBSERVATIONS SO ASTRONOMICAL JOURNAL LA English DT Article ID POWERFUL RADIO GALAXIES; MULTICOLOR SURFACE PHOTOMETRY; ELLIPTICAL GALAXIES; ISOPHOTE SHAPES; REDSHIFT SURVEY; STAR FORMATION; MORPHOLOGY; EVOLUTION; REDUCTION; CATALOG AB As part of an investigation into the triggering of nuclear radio emission in interacting galaxies, we present new multicolor, broadband data from a subset of Arp-Madore Catalog galaxies selected on the basis of their optical morphology-systems with loops and/or tails. Using the CTIO 4 m we obtained images in B, V, R, and I for the purpose of performing synthetic aperture photometry. We also have performed isophotal ellipse fitting to the more regular objects in the sample to quantify their isophotal deviation from purely elliptical morphologies. We constructed color index maps for the galaxies and discuss the optical morphologies, broadband colors, and detailed photometric properties as well as the IRAS fluxes for the galaxies. These data are used to obtain a rough measure of the level of activity present in these systems. The systems observed exhibit: (1) a wide range of colors, from redder than normal disk galaxies or ellipticals to bluer than (B - V) = 0.5. The reddest galaxies are systems with significant amounts of obscuring dust while the bluest galaxies may be experiencing a strong burst of star formation. (2) Contrasting colors in many pairs indicating that star formation is triggered in one and not the other, although sizes and masses are not grossly dissimilar. (3) Apparent superimposed stars seen in many cases, but at least two systems 1325 - 371 and 1925 - 724, appear to contain AGNs. Spectroscopy is required for further analysis of the sample. Later papers will present VLA radio data for these galaxies. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. UNIV NEVADA,DEPT PHYS,LAS VEGAS,NV 89154. NR 57 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 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 1991 VL 101 IS 2 BP 410 EP & DI 10.1086/115693 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EU739 UT WOS:A1991EU73900005 ER PT J AU HUTCHINGS, JB NEFF, SG AF HUTCHINGS, JB NEFF, SG TI EVOLUTION OF LUMINOUS IRAS SOURCES - CCD IMAGING SO ASTRONOMICAL JOURNAL LA English DT Article ID GALAXIES; QUASARS AB We present optical imaging of a sample of 64 luminous IRAS galaxies which cover a wide range of IRAS spectra and luminosity and also include a range of optical types. The objects are almost all in current or recent tidal interaction. We discuss the connections between the strength and age of the interaction, the IR spectrum and luminosity, and the optical colors, and other properties of the galaxies. The principal result is that the powerful IR sources with steep IR spectra are stronger and dynamically younger interacting systems, while the flat IR spectrum objects are older. We discuss star formation, dust obscuration, and the timescales for nuclear activity compared with IR and tidal events. We describe a self-consistent evolution scenario connecting the luminous IR sources. We suggest that there are two principal evolution paths in IR-luminous galaxies, mainly depending on whether a nuclear broad emission-line region is formed. The suggested evolution connects one type of Sy 2 galaxy with LINERs, and another type of Sy 2 with Sy 1 and QSO galaxies. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NATL RES COUNCIL CANADA,CANADA FRANCE HAWAII TELESCOPE,OTTAWA K1A 0R6,ONTARIO,CANADA. CNRS,CANADA FRANCE HAWAII TELESCOPE,F-75005 PARIS,FRANCE. UNIV HAWAII,CANADA FRANCE HAWAII TELESCOPE,HONOLULU,HI 96822. RP HUTCHINGS, JB (reprint author), NATL RES COUNCIL CANADA,DOMIN ASTROPHYS,OBSERV,5071 W SAANICH RD,VICTORIA V8X 4M6,BC,CANADA. NR 21 TC 56 Z9 57 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 FEB PY 1991 VL 101 IS 2 BP 434 EP 446 DI 10.1086/115694 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EU739 UT WOS:A1991EU73900006 ER PT J AU WELCH, DL MATEO, M COTE, P FISCHER, P MADORE, BF AF WELCH, DL MATEO, M COTE, P FISCHER, P MADORE, BF TI THE VARIABLE-STARS OF NGC 1866 SO ASTRONOMICAL JOURNAL LA English DT Article ID LARGE MAGELLANIC CLOUD; LMC CLUSTER NGC-1866; CEPHEID VARIABLES; GLOBULAR-CLUSTERS; PHOTOMETRY; DISTANCE AB New multiepoch CCD photometry of the populous LMC cluster NGC 1866 has been obtained to search for new variables and confirm the variable candidates of Storm et al. (1988). In addition, we have acquired high-dispersion, photon-counting echelle spectra of 18 variables in the field of NGC 1866 which have been used to obtain 106 radial velocities. From these data, we find: (1) Eight previously unknown Cepheid variables, most near the cluster core. (2) Of the new variables reported by Storm et al. (1988), only six (V1, V4, V5, V6, V7, and V8) out of ten appear to be Cepheids and one of these (V5) is not a member. (3) Periods and mean magnitudes and colors for sufficiently uncrowded variables. (4) One red giant variable of long period. (5) One Cepheid (HV 12202) which is a single-lined spectroscopic binary with a velocity semiamplitude greater than or equal to 10.5 km s.-1 (6) The blue and large-amplitude Cepheid HV 12204 is a nonmember from radial velocities. (7) The variation of light-curve amplitude with position in the Instability Strip. (8) An apparently nonvariable star, which is a radial velocity member, in the Instability Strip. (9) A true distance modulus of 18.57 +/- 0.01 mag for the cluster. We determine the color coefficient beta of the Cepheid P-L-C to be 2.03 +/- 0.38 from all uncrowded variables with good phase coverage in the field of the cluster. The scatter in the P-L-C for the nonbinary field variables is only 0.047 mag, which can be accounted for by photometric errors. This indicates that the P-L-C is practically disperionless. There is no evidence for Cepheids in more than one crossing of the Instability Strip. C1 MCMASTER UNIV,DEPT PHYS,HAMILTON L8S 4M1,ONTARIO,CANADA. CARNEGIE INST WASHINGTON,OBSERV,PASADENA,CA 91101. CALTECH,JET PROPULS LAB,CTR INFRARED PROC & ANALYSIS CTR,PASADENA,CA 91125. CARNEGIE INST WASHINGTON,MT WILSON OBSERV,WASHINGTON,DC 20005. CARNEGIE INST WASHINGTON,LAS CAMPANAS OBSERV,WASHINGTON,DC 20005. OI Welch, Doug/0000-0002-2350-0898 NR 36 TC 52 Z9 52 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 FEB PY 1991 VL 101 IS 2 BP 490 EP & DI 10.1086/115700 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EU739 UT WOS:A1991EU73900012 ER PT J AU OSWALT, TD SION, EM HAMMOND, G VAUCLAIR, G LIEBERT, JW WEGNER, G KOESTER, D MARCUM, PM AF OSWALT, TD SION, EM HAMMOND, G VAUCLAIR, G LIEBERT, JW WEGNER, G KOESTER, D MARCUM, PM TI UV OBSERVATIONS OF THE COOL DBQA5 WHITE-DWARF LDS-678A - LIMITS ON THE ATMOSPHERIC COMPOSITION, PRESSURE SHIFT, AND GRAVITATIONAL REDSHIFT DERIVED FROM CI-2479 SO ASTRONOMICAL JOURNAL LA English DT Article ID HELIUM AB We present a high-resolution ultraviolet spectrum of the helium-rich degenerate LDS 678A, obtained with the International Ultraviolet Explorer (IUE) satellite. LDS 678A is the coolest metallic line degenerate (DQ or DZ) yet observed with the IUE echelle. These observations provide a detailed line profile of the strong C I 2479 absorption line and equivalent width W2479 = 2.35 +/- 0.06 angstrom from which theoretical profile fits yield a carbon abundance of log C/He = ( -6.7 +/- 0.2). The presence of carbon in a He-rich atmosphere lends credence to the notion that LDS 678A is a transitional case between the DB white dwarfs with nearly pure helium atmospheres and the helium-rich DQ white dwarfs which exhibit carbon bands. Corrected for an inferred pressure shift V(p) = +38 +/- 4 km/s for the C I 2479 line, a gravitational redshift of V(rs) = +26 +/- 13 km/s is deduced from which a most probable mass of 0.55M. is derived. C1 NASA,GODDARD SPACE FLIGHT CTR,IUE SATELLITE,GREENBELT,MD 20771. FLORIDA INST TECHNOL,DEPT PHYS & SPACE SCI,MELBOURNE,FL 32901. VILLANOVA UNIV,DEPT ASTRON & ASTROPHYS,VILLANOVA,PA 19085. UNIV S FLORIDA,DEPT MATH,ASTRON PROGRAM,PHY 342,TAMPA,FL 33620. UNIV TOULOUSE 3,OBSERV MIDI PYRENEES,OMP-14,F-31400 TOULOUSE,FRANCE. UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. DARTMOUTH COLL,DEPT PHYS & ASTRON,HANOVER,NH 03755. LOUISIANA STATE UNIV,DEPT PHYS & ASTRON,BATON ROUGE,LA 70803. FLORIDA INST TECHNOL,DEPT PHYS & SPACE SCI,MELBOURNE,FL 32901. NR 27 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 0004-6256 J9 ASTRON J JI Astron. J. PD FEB PY 1991 VL 101 IS 2 BP 583 EP 586 DI 10.1086/115707 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA EU739 UT WOS:A1991EU73900019 ER EF