FN Thomson Reuters Web of Science™ VR 1.0 PT J AU HARMON, BA WILSON, CA ZHANG, SN PACIESAS, WS FISHMAN, GJ HJELLMING, RM RUPEN, MP SCOTT, DM BRIGGS, MS RUBIN, BC AF HARMON, BA WILSON, CA ZHANG, SN PACIESAS, WS FISHMAN, GJ HJELLMING, RM RUPEN, MP SCOTT, DM BRIGGS, MS RUBIN, BC TI CORRELATIONS BETWEEN X-RAY OUTBURSTS AND RELATIVISTIC EJECTIONS IN THE X-RAY TRANSIENT GRO J1655-40 SO NATURE LA English DT Article AB ALTHOUGH objects that emit radio jets have been known for many years, the physical mechanism responsible for the jets has been unclear. Accretion of mass onto a compact object (such as a black hole) has often been invoked in models of their formation(1). X-ray emission from such sources is a potentially powerful probe of the processes taking place, because it seems to arise much closer to the central object. Here se report the detection of X-ray and radio emission from the recently discovered(2,3) transient source X-ray Nova Scorpii 1994 (GRO J1655-40). The radio outbursts, presumably reflecting the feeding of material into relativistic jets, generally follow bursts of hard X-ray emission (20-400 keV) with a delay that varies from a few days to about two weeks. This suggests that the mechanism behind the X-ray emission is not related to the ejection process in a simple way. Nevertheless, GRO J1655-40 may be the best example of a compact object/accretion-disk system in which models of jet formation and X-ray production can be tested directly. C1 UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. UNIV SPACE RES ASSOC,HUNTSVILLE,AL 35806. NATL RADIO ASTRON OBSERV,SOCORRO,NM 87801. RP HARMON, BA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,ES84,HUNTSVILLE,AL 35812, USA. NR 22 TC 119 Z9 119 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 20 PY 1995 VL 374 IS 6524 BP 703 EP 706 DI 10.1038/374703a0 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QU304 UT WOS:A1995QU30400043 ER PT J AU SEMIKOZ, DV TKACHEV, II AF SEMIKOZ, DV TKACHEV, II TI KINETICS OF BOSE-CONDENSATION SO PHYSICAL REVIEW LETTERS LA English DT Article ID POLARIZED ATOMIC-HYDROGEN; POPULATION-DYNAMICS; GAS C1 RUSSIAN ACAD SCI,INST NUCL RES,MOSCOW 117312,RUSSIA. RP SEMIKOZ, DV (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510, USA. NR 24 TC 112 Z9 112 U1 1 U2 9 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0031-9007 J9 PHYS REV LETT JI Phys. Rev. Lett. PD APR 17 PY 1995 VL 74 IS 16 BP 3093 EP 3097 DI 10.1103/PhysRevLett.74.3093 PG 5 WC Physics, Multidisciplinary SC Physics GA QT449 UT WOS:A1995QT44900001 ER PT J AU GOSLING, JT BIRN, J HESSE, M AF GOSLING, JT BIRN, J HESSE, M TI 3-DIMENSIONAL MAGNETIC RECONNECTION AND THE MAGNETIC TOPOLOGY OF CORONAL MASS EJECTION EVENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR-WIND; MAGNETOTAIL AB Measurements of suprathermal electron fluxes in the solar wind indicate that field lines within coronal mass ejections, CMEs, near and beyond 1 AU are normally connected to the Sun at both ends. However, on occasion some field lines embedded deep within CMEs appear to be connected to the Sun at only one end. Here we propose an explanation for how such field lines arise in terms of 3-dimensional reconnection close to the Sun. Such reconnection also provides a natural explanation for the flux rope topology characteristic of many CMEs as well as the coronal loops formed during long-duration, solar soft X-ray events. Our consideration of the field topologies resulting from 3-dimensional reconnection indicates that field lines within and near CMEs may on occasion be connected to the outer heliosphere at both ends. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP GOSLING, JT (reprint author), LOS ALAMOS NATL LAB,MS D466,LOS ALAMOS,NM 87545, USA. RI Hesse, Michael/D-2031-2012 NR 15 TC 181 Z9 183 U1 0 U2 5 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 15 PY 1995 VL 22 IS 8 BP 869 EP 872 DI 10.1029/95GL00270 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QT666 UT WOS:A1995QT66600001 ER PT J AU HOLLANDSWORTH, SM MCPETERS, RD FLYNN, LE PLANET, W MILLER, AJ CHANDRA, S AF HOLLANDSWORTH, SM MCPETERS, RD FLYNN, LE PLANET, W MILLER, AJ CHANDRA, S TI OZONE TRENDS DEDUCED FROM COMBINED NIMBUS-7 SBUV AND NOAA-11 SBUV/2 DATA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB The long-term time series of global ozone from the Nimbus-7 SBUV (Nov. 1978-June 1990) are extended through June 1994 by using measurements from the NOAA-11 SBUV/2. The data sets are merged based upon comparisons during the 18-month overlap period in which both instruments were operational. During this period, the average offset between the two time series is less than 2% in total ozone, and less than 6% in Umkehr layers 1-10. A linear-regression trend model is applied to the extended time series to calculate updated trends as a function of latitude and altitude. Trends through June 1994 are 1.5-2% per decade less negative than through June 1990 in the tropical middle stratosphere (35-40 km) and in the upper stratosphere (45-50 km) at mid-latitudes. In the lower stratosphere, the trends are nearly 15% per decade more negative in the southern hemisphere tropical regions to 25 degrees S, but remain relatively unchanged elsewhere. The seasonal structure of the total ozone trends is similar to past trend study results, but the magnitude of the seasonal trend can vary by 2% per decade depending on the length of the time series. Both TOMS (through April 1993) and SBUV total ozone time series show small negative trends in the equatorial region, though they are not statistically significant at the 2-sigma level. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. SOFTWARE CORP AMER,LANHAM,MD 20706. NOAA,ORL,SATELLITE RES LAB,WASHINGTON,DC 20233. NOAA,NWS,CTR CLIMATE ANAL,WASHINGTON,DC 20233. RP HOLLANDSWORTH, SM (reprint author), APPL RES CORP,8201 CORP DR,LANDOVER,MD 20785, USA. RI Flynn, Lawrence/B-6321-2009; McPeters, Richard/G-4955-2013 OI Flynn, Lawrence/0000-0001-6856-2614; McPeters, Richard/0000-0002-8926-8462 NR 9 TC 69 Z9 70 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 15 PY 1995 VL 22 IS 8 BP 905 EP 908 DI 10.1029/95GL00605 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QT666 UT WOS:A1995QT66600010 ER PT J AU HIDE, R AF HIDE, R TI THE TOPOGRAPHIC TORQUE ON A BOUNDING SURFACE OF A ROTATING GRAVITATING FLUID AND THE EXCITATION BY CORE MOTIONS OF DECADAL FLUCTUATIONS IN THE EARTHS ROTATION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MANTLE; FLOW AB General expressions (with potential applications in several areas of geophysical fluid dynamics) are derived for all three components of the contribution made by the geostrophic part of the pressure field associated with flow in a rotating gravitating fluid to the topographic torque exerted by the fluid on a rigid impermeable bounding surface of any shape. When applied to the Earth's liquid metallic core, which is bounded by nearly spherical surfaces and can be divided into two main regions, the ''torosphere'' and ''polosphere,'' the expressions reduce to formulae given previously by the author, thereby providing further support for his work and that of others on the role of topographic coupling at the core-mantle boundary in the excitation by core motions of Earth rotation fluctuations on decadal time scales. They also show that recent criticisms of that work are vitiated by mathematical and physical errors. Contrary to these criticisms, the author's scheme for exploiting Earth rotation and other geophysical data (either real or simulated in computer models) in quantitative studies of the topography of the core-mantle boundary (CMB) by intercomparing various models of (a) motions in the core based on geomagnetic secular variation data and (b) CMB topography based on seismological and gravity data has a sound theoretical basis. The practical scope of the scheme is of course limited by the accuracy of real data, but this is a matter for investigation, not a priori assessment. C1 CALTECH,JET PROP LAB,SPACE GEODET SCI & APPL GRP,PASADENA,CA. NR 26 TC 21 Z9 21 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 15 PY 1995 VL 22 IS 8 BP 961 EP 964 DI 10.1029/95GL00539 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QT666 UT WOS:A1995QT66600024 ER PT J AU JAMES, TS IVINS, ER AF JAMES, TS IVINS, ER TI PRESENT-DAY ANTARCTIC ICE MASS CHANGES AND CRUSTAL MOTION SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID EARTHS ROTATION; SHEET AB The peak vertical velocities predicted by three realistic, but contrasting, present-day scenarios of Antarctic ice sheet mass balance are found to be of the order of several mm/a. One scenario predicts local uplift rates in excess of 5 mm/a. These rates are small compared to the peak Antarctic vertical velocities of the ICE-3G glacial rebound model, which are in excess of 20 mm/a. Lf the Holocene Antarctic deglaciation history portrayed in ICE-3G is realistic, and if regional upper mantle viscosity is not an order of magnitude below 10(21) Pa . s, then a vast geographical region in West Antarctica is uplifting at a rate that could be detected by a future Global Positioning System (GPS) campaign. While present-day scenarios predict small vertical crustal velocities, their overall continent-ocean mass exchange is large enough to account for a substantial portion of the observed secular polar motion (Omega ($) over right arrow m) and time-varying zonal gravity field J(l). C1 UNIV SO CALIF,CALIF INST TECHNOL & EARTH SCI,JET PROP LAB,PASADENA,CA. RP JAMES, TS (reprint author), GEOL SURVEY CANADA,DIV GEOPHYS,1 OBSERV CRES,OTTAWA,ON K1A 0Y3,CANADA. RI James, Thomas/D-9301-2013 OI James, Thomas/0000-0001-7321-047X NR 17 TC 29 Z9 31 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 15 PY 1995 VL 22 IS 8 BP 973 EP 976 DI 10.1029/94GL02800 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QT666 UT WOS:A1995QT66600027 ER PT J AU PHILLIPS, TR MALUENDES, S GREEN, S AF PHILLIPS, TR MALUENDES, S GREEN, S TI COLLISION DYNAMICS FOR AN ASYMMETRIC-TOP ROTOR AND A LINEAR ROTOR - COUPLED-CHANNEL FORMALISM AND APPLICATION TO H2O-H-2 SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID SUBMILLIMETER WATER MASER; ROTATIONAL-EXCITATION; MOLECULES; SCATTERING; ATOMS; APPROXIMATION; ORTHO-H2; PARA-H2; STATES; RATES C1 IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP PHILLIPS, TR (reprint author), SCI SYST APPLICAT INC,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 28 TC 27 Z9 27 U1 0 U2 5 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD APR 15 PY 1995 VL 102 IS 15 BP 6024 EP 6031 DI 10.1063/1.469337 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QT158 UT WOS:A1995QT15800016 ER PT J AU FUKUMORI, I MALANOTTERIZZOLI, P AF FUKUMORI, I MALANOTTERIZZOLI, P TI AN APPROXIMATE KALMAN FILTER FOR OCEAN DATA ASSIMILATION - AN EXAMPLE WITH AN IDEALIZED GULF-STREAM MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ALTIMETRIC SEA-LEVEL; TROPICAL PACIFIC-OCEAN; CIRCULATION MODEL; GENERAL-CIRCULATION; STEADY-STATE; PREDICTION AB A practical method of data assimilation for use with large, nonlinear, ocean general circulation models is explored. A Kalman filter based on approximations of the state error covariance matrix is presented, employing a reduction of the effective model dimension. the error's asymptotic steady state limit, and a time-invariant linearization of the dynamic model for the error integration. The approximations lead to dramatic computational savings in applying estimation theory to large complex systems. We examine the utility of the approximate filter in assimilating different measurement types using a twin experiment of an idealized Gulf Stream. A nonlinear primitive equation model of an unstable east-west jet is studied with a state dimension exceeding 170,000 elements. Assimilation of various pseudomeasurements are examined, including velocity, density, and volume transport at localized arrays and realistic distributions of satellite altimetry and acoustic tomography observations. Results are compared in terms of their effects on the accuracies of the estimation. The approximate filter is shown to outperform an empirical nudging scheme used in a previous study. The examples demonstrate that useful approximate estimation errors dan be computed in a practical manner for general circulation models. C1 MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA. RP FUKUMORI, I (reprint author), CALTECH,JET PROP LAB,MS 300-323,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 34 TC 140 Z9 141 U1 0 U2 9 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD APR 15 PY 1995 VL 100 IS C4 BP 6777 EP 6793 DI 10.1029/94JC03084 PG 17 WC Oceanography SC Oceanography GA QT222 UT WOS:A1995QT22200019 ER PT J AU FERRIER, BS TAO, WK SIMPSON, J AF FERRIER, BS TAO, WK SIMPSON, J TI A DOUBLE-MOMENT MULTIPLE-PHASE 4-CLASS BULK ICE SCHEME .2. SIMULATIONS OF CONVECTIVE STORMS IN DIFFERENT LARGE-SCALE ENVIRONMENTS AND COMPARISONS WITH OTHER BULK PARAMETERIZATIONS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID TROPICAL SQUALL-LINE; MARITIME CUMULIFORM CLOUDS; DROP-SIZE DISTRIBUTIONS; NUMERICAL-SIMULATION; PARTICLE CONCENTRATIONS; PRECIPITATION DEVELOPMENT; MICROSCALE STRUCTURE; MESOSCALE PROCESSES; STRATIFORM CLOUDS; FRONTAL RAINBANDS AB Part I of this study described a detailed four-class bulk ice scheme (4ICE) developed to simulate the hydrometeor profiles of convective and stratiform precipitation associated with mesoscale convective systems. In Part II, the 4ICE scheme is incorporated into the Goddard Cumulus Ensemble (GCE) model and applied without any ''tuning'' to two squall lines occurring in widely different environments, namely, one over the tropical ocean in the Global Atmospheric Research Program's (GARP) Atlantic Tropical Experiment (GATE) and the other over a midlatitude continent in the Cooperative Huntsville Meteorological Experiment (COHMEX). Comparisons were made both with earlier three-class ice formulations and with observations. In both cases, the 4ICE scheme interacted with the dynamics so as to resemble the observations much more closely than did the model runs with either of the three-class ice parameterizations. The following features were well simulated in the COHMEX case: a lack of stratiform rain at the surface ahead of the storm, reflectivity maxima near 60 dBZ in the vicinity of the melting level, and intense radar echoes up to near the tropopause. These features were in strong contrast with the GATE simulation, which showed,extensive trailing stratiform precipitation containing a horizontally oriented radar bright band. Peak reflectivities were below the melting level, rarely exceeding 50 dBZ, with a steady decrease in reflectivity with height above. With the other bulk,formulations, the large stratiform rain areas were not reproduced in the GATE conditions. The microtphysical structure of the model clouds in both environments were more realistic than that of earlier modeling efforts. Number concentrations of ice of O(100 L(-1)) occurred above 6 km in the GATE model clouds as a result of ice enhancement and rime splintering in the 4ICE runs. These processes were more effective in the GATE simulation, because near the freezing level the weaker updrafts were comparable in magnitude to the fall speeds of newly frozen drops. Many of the ice crystals initiated at relatively warm temperatures (above -15 degrees C) grew rapidly by deposition into sizes large enough to be converted to snow. In contrast, in the more intense COHMEX updrafts, very large numbers of small ice crystals were initiated at colder temperatures (below -15 degrees C) by nucleation and stochastic freezing of droplets, such that relatively few ice crystals grew by deposition to sizes large enough to be converted to snow. In addition, the large number of frozen drops of O(5 L(-1))in the 4ICE run are consistent with airborne microphysical data in intense COHMEX updrafts. Numerous sensitivity experiments were made with the four-class and three-class ice schemes, varying fall speed relationships, particle characteristics, and ice collection efficiencies. These-tests provide strong support to the conclusion that the 4ICE scheme gives improved resemblance to observations despite present uncertainties in a number of important microphysical parameters. C1 NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP FERRIER, BS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,MESOSCALE DYNAM & PRECIPITAT BRANCH,CODE 912,GREENBELT,MD 20771, USA. NR 89 TC 103 Z9 105 U1 1 U2 10 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 15 PY 1995 VL 52 IS 8 BP 1001 EP 1033 DI 10.1175/1520-0469(1995)052<1001:ADMMPF>2.0.CO;2 PG 33 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QV955 UT WOS:A1995QV95500001 ER PT J AU CHOU, MD RIDGWAY, WL YAN, MMH AF CHOU, MD RIDGWAY, WL YAN, MMH TI PARAMETERIZATIONS FOR WATER-VAPOR IR RADIATIVE-TRANSFER IN BOTH THE MIDDLE AND LOWER ATMOSPHERES SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID TRANSMISSION FUNCTIONS; ABSORPTION; CO2; CLIMATE; MODELS; BANDS AB Water vapor contributes a maximum of 1 degrees C/day to the middle atmospheric thermal infrared (IR) cooling. This magnitude is small but not negligible. Because of the small amount of mass involved and the extremely narrow molecular absorption lines at pressures less than 1 mb, only a few existing parameterizations can compute accurately the water vapor cooling in this region. The accuracy and efficiency of two IR parameterizations are examined in this study. One is the correlated-k distribution method, and the other is the table look-up using precomputed transmission functions. Both methods can accurately compute the cooling rate from the earth's surface to 0.01 mb with an error of only a few percent. The contribution to the cooling rate at pressures < 1 mb comes from a very small fraction (<0.005) of the spectrum near the centers of the absorption bands, where the absorption coefficient varies by four orders of magnitude. It requires at least 100 terms of the k-distribution function to accurately compute the cooling profile. The method of table look-up is, therefore, much faster than the correlated-k distribution method for computing the water vapor cooling profile involving both the middle and lower atmospheres. RP CHOU, MD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 913,GREENBELT,MD 20771, USA. NR 22 TC 30 Z9 32 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD APR 15 PY 1995 VL 52 IS 8 BP 1159 EP 1167 DI 10.1175/1520-0469(1995)052<1159:PFWVIR>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QV955 UT WOS:A1995QV95500011 ER PT J AU ACKERMAN, AS TOON, OB HOBBS, PV AF ACKERMAN, AS TOON, OB HOBBS, PV TI A MODEL FOR PARTICLE MICROPHYSICS, TURBULENT MIXING, AND RADIATIVE-TRANSFER IN THE STRATOCUMULUS-TOPPED MARINE BOUNDARY-LAYER AND COMPARISONS WITH MEASUREMENTS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID CLOUD CONDENSATION NUCLEI; STRATIFORM CLOUDS; MIXED LAYER; NOCTURNAL STRATOCUMULUS; CCN CONCENTRATIONS; OPTICAL-PROPERTIES; SURFACE-LAYER; CLOSURE-MODEL; STRATUS; AEROSOLS AB A detailed 1D model of the stratocumulus-topped marine boundary layer is described. The model has three coupled components: a microphysics module that resolves the size distributions of aerosols and cloud droplets, a turbulence module that treats vertical mixing between layers, and a multiple wavelength radiative transfer module that calculates radiative heating rates and cloud optical properties. The results of a 12-h model simulation reproduce reasonably well the bulk thermodynamics, microphysical properties, and radiative fluxes measured in an similar to 500-m thick, summertime marine stratocumulus cloud layer by Nicholls. However, in this case, the model predictions of turbulent fluxes between the cloud and subcloud layers exceed the measurements. Results of model simulations are also compared to measurements of a marine stratus layer made under gale conditions and with measurements of a high, thin marine stratocumulus layer. The variations in cloud properties are generally reproduced by the model, although it underpredicts the entrainment of overlying air at cloud top under gale conditions. Sensitivities of the model results are explored. The vertical profile of cloud droplet concentration is sensitive to the lower size cutoff of the droplet size distribution due to the presence of unactivated haze particles in the lower region of the modeled cloud. Increases in total droplet concentrations do not always produce less drizzle and more cloud water in the model. The radius of the mean droplet volume does not correlate consistently with drizzle, but the effective droplet radius does. The greatest impacts on cloud properties predicted by the model are produced by halving the width of the size distribution of input condensation nuclei and by omitting the effect of cloud-top radiative cooling on the condensational growth of cloud droplets. The omission of infrared scattering produces noticeable changes in cloud properties. The collection efficiencies for droplets <30-mu m radius, and the value of the accommodation coefficient for condensational droplet growth, have noticeable effects on cloud properties. The divergence of the horizontal wind also has a significant effect on a 12-h model simulation of cloud structure. Conclusions drawn from the model are tentative because of the limitations of the 1D model framework. A principal simplification is that the model assumes horizontal homogeneity, and, therefore, does not resolve updrafts and downdrafts. Likely consequences of this simplification include overprediction of the growth of droplets by condensation in the upper region of the cloud, underprediction of droplet condensational growth in the lower region of the cloud, and underprediction of peak supersaturations. C1 UNIV WASHINGTON,DEPT ATMOSPHER SCI,AK-40,SEATTLE,WA 98195. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RI Ackerman, Andrew/D-4433-2012 OI Ackerman, Andrew/0000-0003-0254-6253 NR 64 TC 97 Z9 102 U1 1 U2 11 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 15 PY 1995 VL 52 IS 8 BP 1204 EP 1236 DI 10.1175/1520-0469(1995)052<1204:AMFPMT>2.0.CO;2 PG 33 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QV955 UT WOS:A1995QV95500015 ER PT J AU HARRIS, NW YAU, KKC HUGHES, DW AF HARRIS, NW YAU, KKC HUGHES, DW TI THE TRUE EXTENT OF THE NODAL DISTRIBUTION OF THE PERSEID METEOROID STREAM SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE CELESTIAL MECHANICS, STELLAR DYNAMICS; COMETS, INDIVIDUAL, P/SWIFT-TUTTLE; METEORS, METEOROIDS ID COMET SWIFT-TUTTLE; MASS AB The observed semimajor axis distribution of the Perseid stream requires meteoroids to be ejected from the nucleus of P/Swift-Tuttle with velocities that have a Maxwellian distribution, the most probable velocity being about 0.6 km s(-1). The mass loss is reasonably symmetrical with respect to the time of perihelion passage. The cometary nucleus spins in a prograde fashion, maximum dust emission occurring at a lag angle of about - 5 degrees +/- 10 degrees. It has been found that the Earth only samples the 'inner edge' of the Perseid stream and that the core of the descending nodal distribution of the actual Perseids extends out to heliocentric distances of at least 1.2 au. In order to reach this conclusion the orbit of the Perseid parent comet, P/Swift-Tuttle, has been integrated backwards in time over a period of 270 000 years. Only over the last 160 000 years has the decay of this comet led to the production of any Perseid meteoroids that can be observed from Earth. Previously the mass of the Perseid stream was estimated to be about 3 x 10(17) g. This must now be taken to be a lower limit. In order to produce this mass, however, the mass lost per perihelion passage by P/Swift-Tuttle must have been much greater in the past than it has been over the last 20 or so orbits. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. RP HARRIS, NW (reprint author), UNIV SHEFFIELD,DEPT PHYS,SHEFFIELD S3 7RH,S YORKSHIRE,ENGLAND. NR 26 TC 22 Z9 22 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 APR 15 PY 1995 VL 273 IS 4 BP 999 EP 1015 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU568 UT WOS:A1995QU56800015 ER PT J AU TANI, MG NARANJO, FL BARNES, NP MURRAY, KE LOCKARD, GE AF TANI, MG NARANJO, FL BARNES, NP MURRAY, KE LOCKARD, GE TI DIODE-PUMPED LONG-PULSE-LENGTH HO-TM-YLIF4 LASER AT 10-HZ SO OPTICS LETTERS LA English DT Article ID OPERATION; TM AB An optical efficiency of 0.052 under normal mode operation for diode-pumped Ho:Tm:YLiF4 at a pulse repetition frequency of 10 Hz has been achieved. Laser output energy of 30 mJ in single Q-switched pulses with 600-ns pulse length were obtained for an input energy of 3 J. A diffusion-bonded birefringent laser rod consisting of Ho:Tm-doped and undoped pieces of YLF was utilized for 10-Hz operation. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP TANI, MG (reprint author), SCI & TECHNOL CORP,101 RES DR,HAMPTON,VA 23666, USA. NR 14 TC 23 Z9 23 U1 1 U2 2 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 15 PY 1995 VL 20 IS 8 BP 872 EP 874 DI 10.1364/OL.20.000872 PG 3 WC Optics SC Optics GA QT452 UT WOS:A1995QT45200023 PM 19859358 ER PT J AU MORELLI, DT CAILLAT, T FLEURIAL, JP BORSHCHEVSKY, A VANDERSANDE, J CHEN, B UHER, C AF MORELLI, DT CAILLAT, T FLEURIAL, JP BORSHCHEVSKY, A VANDERSANDE, J CHEN, B UHER, C TI LOW-TEMPERATURE TRANSPORT-PROPERTIES OF P-TYPE COSB3 SO PHYSICAL REVIEW B LA English DT Article ID INFRARED REFLECTION SPECTRA; THERMAL-CONDUCTIVITY; SINGLE-CRYSTALS; THERMOELECTRIC-POWER; COAS3; COP3 C1 CALTECH,JET PROPULS LAB,PASADENA,CA 90210. UNIV MICHIGAN,DEPT PHYS,ANN ARBOR,MI 48109. RP MORELLI, DT (reprint author), GM CORP,CTR RES & DEV,DEPT PHYS,WARREN,MI 48090, USA. RI Uher, Ctirad/M-9966-2014 NR 32 TC 237 Z9 246 U1 5 U2 54 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 1995 VL 51 IS 15 BP 9622 EP 9628 DI 10.1103/PhysRevB.51.9622 PG 7 WC Physics, Condensed Matter SC Physics GA QV237 UT WOS:A1995QV23700021 ER PT J AU LEIFER, SD GOODWIN, DG ANDERSON, MS ANDERSON, JR AF LEIFER, SD GOODWIN, DG ANDERSON, MS ANDERSON, JR TI THERMAL-DECOMPOSITION OF A FULLERENE MIX SO PHYSICAL REVIEW B LA English DT Article ID C-60; CARBON; PHASE; BUCKMINSTERFULLERENE; FRAGMENTATION; IONIZATION; C60 C1 CALTECH,JET PROPULS LAB,PASADENA,CA 91109. RP LEIFER, SD (reprint author), CALTECH,DEPT APPL PHYS,PASADENA,CA 91125, USA. NR 21 TC 54 Z9 54 U1 0 U2 7 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 1995 VL 51 IS 15 BP 9973 EP 9978 DI 10.1103/PhysRevB.51.9973 PG 6 WC Physics, Condensed Matter SC Physics GA QV237 UT WOS:A1995QV23700068 ER PT J AU GERSHENSON, ME ECHTERNACH, PM MIKHALCHUK, AG BOZLER, HM BOGDANOV, AL NILSSON, B AF GERSHENSON, ME ECHTERNACH, PM MIKHALCHUK, AG BOZLER, HM BOGDANOV, AL NILSSON, B TI NONLOCAL EFFECTS IN THE RESISTANCE OF ONE-DIMENSIONAL WIRES WITH DANGLING SIDE BRANCHES SO PHYSICAL REVIEW B LA English DT Note ID WEAK LOCALIZATION; THIN WIRES; FLUCTUATIONS; DEVICES C1 RUSSIAN ACAD SCI,INST RADIO ENGN & ELECTR,MOSCOW 103907,RUSSIA. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV SO CALIF,DEPT PHYS & ASTRON,LOS ANGELES,CA 90089. CHALMERS UNIV TECHNOL,SWEDISH NANOMETER LAB,S-41296 GOTHENBURG,SWEDEN. NR 16 TC 8 Z9 8 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 APR 15 PY 1995 VL 51 IS 15 BP 10256 EP 10259 DI 10.1103/PhysRevB.51.10256 PG 4 WC Physics, Condensed Matter SC Physics GA QV237 UT WOS:A1995QV23700114 ER PT J AU SIGL, G AF SIGL, G TI NEUTRINO MIXING CONSTRAINTS AND SUPERNOVA NUCLEOSYNTHESIS SO PHYSICAL REVIEW D LA English DT Article ID EARLY UNIVERSE; R-PROCESS; OSCILLATIONS; MATTER; SPECTROSCOPY C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP SIGL, G (reprint author), UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637, USA. NR 36 TC 57 Z9 56 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 1995 VL 51 IS 8 BP 4035 EP 4044 DI 10.1103/PhysRevD.51.4035 PG 10 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA QU711 UT WOS:A1995QU71100008 ER PT J AU BHATTACHARJEE, P SIGL, G AF BHATTACHARJEE, P SIGL, G TI MONOPOLE ANNIHILATION AND HIGHEST ENERGY COSMIC-RAYS SO PHYSICAL REVIEW D LA English DT Article ID MAGNETIC MONOPOLES; SUPERCONDUCTING STRINGS; TOPOLOGICAL DEFECTS; FLUX; RADIATION; SPECTRUM; PARTICLES; ORIGIN; FIELDS; LIMITS C1 INDIAN INST ASTROPHYS,BANGALORE 560034,KARNATAKA,INDIA. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. RP BHATTACHARJEE, P (reprint author), UNIV CAMBRIDGE,ISAAC NEWTON INST,20 CLARKSON RD,CAMBRIDGE CB3 0EH,ENGLAND. NR 67 TC 67 Z9 68 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 1995 VL 51 IS 8 BP 4079 EP 4091 DI 10.1103/PhysRevD.51.4079 PG 13 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA QU711 UT WOS:A1995QU71100012 ER PT J AU DOLGOV, AD KAINULAINEN, K ROTHSTEIN, IZ AF DOLGOV, AD KAINULAINEN, K ROTHSTEIN, IZ TI BOUNDS ON DIRAC NEUTRINO MASSES FROM NUCLEOSYNTHESIS SO PHYSICAL REVIEW D LA English DT Article ID PRIMORDIAL NUCLEOSYNTHESIS; TAU-NEUTRINO; CONSTRAINTS; SN-1987A; LIMIT; NUMBER C1 FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV MICHIGAN,RANDALL LAB PHYS,ANN ARBOR,MI 48109. UNIV MINNESOTA,SCH PHYS & ASTRON,MINNEAPOLIS,MN 55455. RP DOLGOV, AD (reprint author), INST THEORET & EXPTL PHYS,MOSCOW 117259,RUSSIA. RI Rothstein, Ira/O-2747-2014 OI Rothstein, Ira/0000-0002-3374-4212 NR 25 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 0556-2821 J9 PHYS REV D JI Phys. Rev. D PD APR 15 PY 1995 VL 51 IS 8 BP 4129 EP 4133 DI 10.1103/PhysRevD.51.4129 PG 5 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA QU711 UT WOS:A1995QU71100017 ER PT J AU BRAGE, T LECKRONE, D AF BRAGE, T LECKRONE, D TI OSCILLATOR-STRENGTHS FOR TRANSITIONS IN AS-II SO JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS LA English DT Article ID GENERAL PROGRAM; PACKAGE AB Theoretical oscillator strengths for transitions between the even 4s(2) 4p(2) and the three odd {4s4p(3), 4s(2)4p4d, 4s(2)4p5s} configurations of As+ are reported. Both ab initio, multiconfiguration Hartree-Fock and semiempirical configuration interaction techniques are used. The uncertainty of the results are estimated, by considering the reproduced energy structure, the agreement of results from the two methods and cancellation effects in the transition elements. For the strongest transitions the estimated uncertainty is about 10%. RP BRAGE, T (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 681,GREENBELT,MD 20771, USA. OI Brage, Tomas/0000-0003-3985-767X NR 19 TC 8 Z9 8 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0953-4075 J9 J PHYS B-AT MOL OPT JI J. Phys. B-At. Mol. Opt. Phys. PD APR 14 PY 1995 VL 28 IS 7 BP 1201 EP 1210 DI 10.1088/0953-4075/28/7/014 PG 10 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA QU522 UT WOS:A1995QU52200014 ER PT J AU DUDLEY, M HUANG, W WANG, S POWELL, JA NEUDECK, P FAZI, C AF DUDLEY, M HUANG, W WANG, S POWELL, JA NEUDECK, P FAZI, C TI WHITE-BEAM SYNCHROTRON TOPOGRAPHIC ANALYSIS OF MULTI-POLYTYPE SIC DEVICE CONFIGURATIONS SO JOURNAL OF PHYSICS D-APPLIED PHYSICS LA English DT Article ID CHEMICAL VAPOR-DEPOSITION; 6H; FILMS AB White-beam synchrotron topographic analysis of SiC device configurations of various polytypes has been carried out. The devices, p-n junctions of area 1 mm(2), were fabricated via chemical vapour deposition epilayer growth of nominally 3C- or 6H-SiC, on 6H-SiC substrates grown by either the physical vapour transport or the Lely technique. Detailed analysis of diffracted intensities from the different device areas in grazing reflection geometry, using a specially developed computer program, is presented. Depth profiling carried out using variable penetration depth, grazing-incidence geometries reveals both the polytype configuration and the defect structure as a function of depth in these multi-polytype epilayers. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. USA,RES LAB,SLCHD NW RF,ADELPHI,MD 20783. RP DUDLEY, M (reprint author), SUNY STONY BROOK,DEPT MAT SCI & ENGN,STONY BROOK,NY 11794, USA. NR 17 TC 15 Z9 15 U1 0 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0022-3727 J9 J PHYS D APPL PHYS JI J. Phys. D-Appl. Phys. PD APR 14 PY 1995 VL 28 IS 4A SI SI BP A56 EP A62 DI 10.1088/0022-3727/28/4A/011 PG 7 WC Physics, Applied SC Physics GA QX640 UT WOS:A1995QX64000013 ER PT J AU HABERLE, RM AF HABERLE, RM TI PLANETARY SCIENCE - BURIED DRY ICE ON MARS SO NATURE LA English DT Editorial Material RP HABERLE, RM (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 8 TC 0 Z9 0 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 13 PY 1995 VL 374 IS 6523 BP 595 EP 596 DI 10.1038/374595a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QT189 UT WOS:A1995QT18900035 PM 7715695 ER PT J AU AMINI, AM AF AMINI, AM TI ITERATIVE DECONVOLUTION WITH VARIABLE CONVERGENCE SPEED OF THE ITERATIONS SO APPLIED OPTICS LA English DT Article ID LINEARLY DEGRADED IMAGES; RESTORATION AB A fast iterative deconvolution technique that permits the convergence speed of the iterations to be varied is introduced. In this technique, iterations are made to converge as fast as, twice as fast as, and three times (i.e., any integer may be used) as fast as the ordinary methods. The speed of convergence depends on the amount of noise in the data being deconvoluted. This technique is particularly useful for speeding up convergence of the reblurring procedure. The technique converges for all impulse-response function types. The mean-square error versus the deconvolution iteration number for different integral values of the convergence speed of the iterations (1, 5, and 10) is studied for two data sets with and without noise. It is shown that for noisy data sets one has to have control over the convergence speed of the iterations. This technique is also tested with a real data set obtained from an optical multichannel analyzer. C1 SO UNIV A&M,DEPT ELECTR ENGN TECHNOL,BATON ROUGE,LA 70813. RP AMINI, AM (reprint author), NASA,JOHN C STENNIS SPACE CTR,DIV TECHNOL & SENSOR DEV,MAIL CODE KA60,BAY ST LOUIS,MS 39529, USA. NR 25 TC 5 Z9 5 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 1995 VL 34 IS 11 BP 1878 EP 1884 PG 7 WC Optics SC Optics GA QR785 UT WOS:A1995QR78500016 PM 21037734 ER PT J AU SMITH, DM LEVENTHAL, M GEHRELS, N TUELLER, J JOHNSON, WN KINZER, RL KURFESS, JD STRICKMAN, MS GRABELSKY, DA PURCELL, WR ULMER, MP JUNG, GV AF SMITH, DM LEVENTHAL, M GEHRELS, N TUELLER, J JOHNSON, WN KINZER, RL KURFESS, JD STRICKMAN, MS GRABELSKY, DA PURCELL, WR ULMER, MP JUNG, GV TI SEARCH FOR COMPTON-BACKSCATTERED ANNIHILATION RADIATION FROM THE GALACTIC-CENTER WITH THE OSSE SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, CENTER; GAMMA-RAYS, OBSERVATIONS ID MOLECULAR CLOUD; LINE EMISSION; CENTER REGION; 1E1740.7-2942; TRANSIENT; NOVA AB An emission feature near 170 keV, interpreted as Compton-backscattered 511 keV positron-annihilation radiation, has been reported twice by balloon-borne germanium spectrometers from within similar to 15 degrees of the Galactic center (Leventhal, MacCallum, and Stang 1978; Smith et al. 1993). Upper limits on this feature set by HEAO 3 (Mahoney, Ling, and Wheaten 1993) and other instruments indicate that it must be transient. We have searched data from the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (CGRO) for this feature, using daily spectral accumulations from all pointings near the Galactic center up to 1993 August, and covering most of the region viewed by the balloon instruments. We find no evidence for backscatter emission. Under the hypothesis that the source is 1E 1740.7-2942, the OSSE data set (186 days) disagrees with the balloon measurements with 99.3% confidence. The average daily 3 sigma OSSE upper limit on backscatter flux from 1E 1740.7-2942 is 6.8 10(-4) photons cm(-2) s(-1), compared to the 1.3 x 10(-3) photons cm(-2) reported by the balloon observations. We also saw no evidence in 186 days for linelike emission from the point source EXS 1737.9-2952 recently discovered by Grindlay, Covault, and Manandhar (1993). This source exhibited bright emission from 83-111 keV, which has been interpreted as doubly backscattered 511 keV radiation. The average daily 3 sigma upper limit from OSSE for this line is 9.8 x 10(-4) photons cm(-2) s(-1), or similar to 8% of the reported flux. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. USN,RES LAB,EO HULBURT CTR SPACE RES,WASHINGTON,DC 20375. NORTHWESTERN UNIV,EVANSTON,IL 60208. UNIV SPACE RES ASSOC,WASHINGTON,DC 20024. RP SMITH, DM (reprint author), UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742, USA. RI Gehrels, Neil/D-2971-2012; Tueller, Jack/D-5334-2012; Johnson, Neil/G-3309-2014 NR 21 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1995 VL 443 IS 1 BP 117 EP 123 DI 10.1086/175507 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ879 UT WOS:A1995QQ87900012 ER PT J AU WOLFIRE, MG HOLLENBACH, D MCKEE, CF TIELENS, AGGM BAKES, ELO AF WOLFIRE, MG HOLLENBACH, D MCKEE, CF TIELENS, AGGM BAKES, ELO TI THE NEUTRAL ATOMIC PHASES OF THE INTERSTELLAR-MEDIUM SO ASTROPHYSICAL JOURNAL LA English DT Review DE DUST, EXTINCTION; ISM, GENERAL ID POLYCYCLIC AROMATIC-MOLECULES; HIGH GALACTIC LATITUDE; INTER-STELLAR MEDIUM; PHOTODISSOCIATION REGIONS; CARBON ABUNDANCES; INFRARED-EMISSION; PAH MOLECULES; ORION NEBULA; SMALL GRAINS; C-I AB We calculate the thermal equilibrium gas temperature of the diffuse interstellar medium. Our method incorporates a new photoelectric heating rate from small grains and PAHs that accounts for a size distribution of particles extending from 100 to 3 Angstrom in radius. We also include a detailed treatment of the ionization rates and heating due to the soft X-ray background and due to cosmic rays. Phase diagrams (thermal pressure P versus hydrogen density n) are presented for gas that is illuminated by the local interstellar far-ultraviolet (FUV) and X-ray radiation fields. A stable two-phase medium is produced with thermal pressure in the range P/k similar or equal to 10(3)-10(4) K cm(-3). We demonstrate that photoelectric heating from PAHs dominates in the warm neutral phase (WNM) and cold neutral phase (CNM). The WNM is cooled by Ly alpha C II (158 mu m), O I (63 mu m), and electron recombinations onto positively charged grains. The CNM is cooled primarily by C II (158 mu m). The C II (158 mu m) cooling per hydrogen nucleus ranges from 2.6 to 6.6 x 10(-26) ergs s(-1) H-1 in the CNM and 0.31 to 0.81 x 10(-26) ergs s(-1) H-1 in the WNM, which compares favorably to recent observations. If the C II (158 mu m) cooling per hydrogen nucleus in the solar neighborhood represents an average value for the Galaxy, we predict L(C II) similar or equal to 7 x 10(7) L. from the CNM in the Galaxy, comparable to that observed by COBE. We discuss the dependence of the results on absorbing column density (10(18) cm(-2) < N-W < 10(20) cm(-2)), gas-phase abundances (variations in C and O of similar to 2), dust abundances and metallicity (from 0.003 to 3 times solar), FUV field (0.3-1000 times local values), and the X-ray radiation field (two models of background X-ray fluxes). These results will be useful in modeling the multiphase structure of high-velocity clouds in the halo, the ISM at other galactocentric radii, and the ISM in external galaxies and galactic nuclei. C1 UNIV CALIF BERKELEY, DEPT PHYS, BERKELEY, CA 94720 USA. UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. PRINCETON UNIV, PRINCETON, NJ 08544 USA. RP WOLFIRE, MG (reprint author), NASA, AMES RES CTR, MS 245-3, MOFFETT FIELD, CA 94035 USA. NR 101 TC 519 Z9 521 U1 1 U2 5 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 10 PY 1995 VL 443 IS 1 BP 152 EP 168 DI 10.1086/175510 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ879 UT WOS:A1995QQ87900015 ER PT J AU ARMSTRONG, JW RICKETT, BJ SPANGLER, SR AF ARMSTRONG, JW RICKETT, BJ SPANGLER, SR TI ELECTRON-DENSITY POWER SPECTRUM IN THE LOCAL INTERSTELLAR-MEDIUM SO ASTROPHYSICAL JOURNAL LA English DT Review DE ISM, STRUCTURE; PULSAR, GENERAL; RADIO CONTINUUM, ISM; TURBULENCE ID PULSAR DISPERSION MEASURES; LOW-FREQUENCY VARIABILITY; MAGNETOHYDRODYNAMIC TURBULENCE; SOLAR-WIND; REFRACTIVE SCINTILLATION; GRAVITATIONAL-RADIATION; EXTRAGALACTIC SOURCES; INTENSITY VARIATIONS; PLASMA TURBULENCE; CYGNUS REGION AB Interstellar scintillation (ISS), fluctuations in the amplitude and phase of radio waves caused by scattering in the interstellar medium, is important as a diagnostic of interstellar plasma turbulence. ISS is also of interest because it is noise for other radio astronomical observations. The unifying concern is the power spectrum of the interstellar electron density. Here we use ISS observations through the nearby (less than or similar to 1 kpc) ISM to estimate the spectrum. From measurements of angular broadening of pulsars and extragalactic sources, decorrelation bandwidth of pulsars, refractive steering of features in pulsar dynamic spectra, dispersion measure fluctuations of pulsars, and refractive scintillation index measurements, we construct a composite structure function that is approximately power law over 2 x 10(6) m < scale < 10(13) m. The data are consistent with the structure function having a logarithmic slope versus baseline less than 2; thus there is a meaningful connection between scales in the radiowave fluctuation field and the scales in the electron density field causing the scattering. The data give an upper limit to the inner scale, l(0), less than or similar to 10(8) m and are consistent with much smaller values. We construct a composite electron density spectrum that is approximately power law over at least the approximate to 5 decade wavenumber range 10(-13) m(-1) < wavenumber < 10(-8) m(-1) and that may extend to higher wavenumbers. The average spectral index of the electron density over this wavenumber range is approximate to 3.7, very close to the value expected for a Kolmogorov process. The outer scale size, L(0), must be greater than or similar to 10(13) m (determined from dispersion measure fluctuations). When the ISS data are combined with measurements of differential Faraday rotation angle, and gradients in the average electron density, constraints can be put on the spectrum at much smaller wave numbers. The composite spectrum is consistent with a Kolmogorov-like power law over a huge range (10 or more decades) of spatial wavenumber with an inferred outer scale, L(0) greater than or similar to 10(18) m. This power-law subrange-expressed as ratio of outer to inner scales-is comparable to or larger than that of other naturally occurring turbulent fluids, such as the oceans or the solar wind. We outline some of the theories for generating and maintaining such a spectrum over this huge wavenumber range. C1 UNIV CALIF SAN DIEGO,DEPT ELECT & COMP ENGN,LA JOLLA,CA 92093. UNIV IOWA,DEPT PHYS & ASTRON,IOWA CITY,IA 52242. RP ARMSTRONG, JW (reprint author), CALTECH,JET PROP LAB,MAIL STOP 238-737,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 112 TC 476 Z9 477 U1 2 U2 11 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 1995 VL 443 IS 1 BP 209 EP 221 DI 10.1086/175515 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ879 UT WOS:A1995QQ87900020 ER PT J AU FEIBELMAN, WA AF FEIBELMAN, WA TI RECENT CHANGES IN THE IUE SPECTRUM OF THE VERY YOUNG PLANETARY-NEBULA HE-3-1357 (=SAO-244567) SO ASTROPHYSICAL JOURNAL LA English DT Article DE PLANETARY NEBULAE, INDIVIDUAL (HE 3-1357); ULTRAVIOLET, STARS AB We obtained the first high-dispersion IUE spectrum, and an additional low-dispersion spectrum, of the very young planetary nebula He 3-1357 and its central star SAO 244567. In 1988, it showed a very strong C IV lambda 1549 P Cygni profile which diminished and has disappeared by 1994, but C IV absorptions are seen in a high-resolution spectrum. The electron density from the C III] F(lambda 1907)/F(lambda 1909) emission ratio is log N-e = 4.1 cm(-3). The older IUE data were reprocessed, and emission-line fluxes vary greatly for the period 1988-1994. The high-dispersion data show a rich Fe V and Fe VI absorption spectrum. RP FEIBELMAN, WA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,CODE 6841,GREENBELT,MD 20771, USA. NR 12 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 10 PY 1995 VL 443 IS 1 BP 245 EP 248 DI 10.1086/175519 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ879 UT WOS:A1995QQ87900024 ER PT J AU JOHNSON, HR ENSMAN, LM ALEXANDER, DR AVRETT, EH BROWN, A CARPENTER, KG ERIKSSON, K GUSTAFSSON, B JORGENSEN, UG JUDGE, PD LINSKY, JL LUTTERMOSER, DG QUERCI, F QUERCI, M ROBINSON, RD WING, RF AF JOHNSON, HR ENSMAN, LM ALEXANDER, DR AVRETT, EH BROWN, A CARPENTER, KG ERIKSSON, K GUSTAFSSON, B JORGENSEN, UG JUDGE, PD LINSKY, JL LUTTERMOSER, DG QUERCI, F QUERCI, M ROBINSON, RD WING, RF TI OUTER LAYERS OF A CARBON STAR - THE VIEW FROM THE HUBBLE-SPACE-TELESCOPE SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, CARBON; STARS, CHROMOSPHERES; STARS, MASS LOSS; ULTRAVIOLET, STARS ID MASS-LOSS RATES; GIANT STARS; CIRCUMSTELLAR ENVELOPES; EVOLVED STARS; TX-PISCIUM; COOL; CHROMOSPHERES; EVOLUTION; SPECTRA; VELOCITIES AB To advance our understanding of the relationship between stellar chromospheres and mass loss, which is a common property of carbon stars and other asymptotic giant branch stars, we have obtained ultraviolet spectra of the nearby N-type carbon star UU Aur using the Hubble Space Telescope (HST). In this paper we describe the HST observations, identify spectral features in both absorption and emission, and attempt to infer the velocity field in the chromosphere, upper photosphere, and circumstellar envelope from spectral line shifts. A mechanism for producing fluoresced emission to explain a previously unobserved emission line is proposed. Some related ground-based observations are also described. C1 WICHITA STATE UNIV,DEPT PHYS,WICHITA,KS 67208. SMITHSONIAN ASTROPHYS OBSERV,CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV COLORADO,JILA,BOULDER,CO 80309. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. ASTRON OBSERV,S-75120 UPPSALA,SWEDEN. NIELS BOHR INST,DK-2100 COPENHAGEN,DENMARK. NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. APPL RES CORP,LANDOVER,MD 20785. OHIO STATE UNIV,DEPT ASTRON,COLUMBUS,OH 43210. UNIV COLORADO,NATL INST STAND & TECHNOL,DIV QUANTUM PHYS,BOULDER,CO 80309. RP JOHNSON, HR (reprint author), INDIANA UNIV,DEPT ASTRON,SWAIN W 319,BLOOMINGTON,IN 47405, USA. RI Carpenter, Kenneth/D-4740-2012 NR 48 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 APR 10 PY 1995 VL 443 IS 1 BP 281 EP 294 DI 10.1086/175525 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ879 UT WOS:A1995QQ87900030 ER PT J AU ROBINSON, EL WOOD, JH BLESS, RC CLEMENS, JC DOLAN, JF ELLIOT, JL NELSON, MJ PERCIVAL, JW TAYLOR, MJ VANCITTERS, GW ZHANG, E AF ROBINSON, EL WOOD, JH BLESS, RC CLEMENS, JC DOLAN, JF ELLIOT, JL NELSON, MJ PERCIVAL, JW TAYLOR, MJ VANCITTERS, GW ZHANG, E TI HUBBLE-SPACE-TELESCOPE OBSERVATIONS OF THE DWARF NOVA Z-CHAMAELEONTIS THROUGH 2 ERUPTION CYCLES SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION, ACCRETION DISKS BINARIES, ECLIPSING; NOVAE, CATACLYSMIC VARIABLES; STARS, INDIVIDUAL (Z CHAMAELEONTIS); ULTRAVIOLET, STARS ID HIGH-SPEED PHOTOMETRY; CATACLYSMIC VARIABLE-STARS; Z-CHA; ACCRETION DISK; MAGNETIC BRAKING; NORMAL OUTBURST; OY-CARINAE; UV SPECTROSCOPY; WHITE-DWARF; EVOLUTION AB We have obtained the first high-speed photometry of the eclipsing dwarf nova Z Cha at ultraviolet wavelengths with the Hubble Space Telescope. We observed the eclipse roughly every 4 days over two cycles of the normal eruptions of Z Cha, giving a uniquely complete coverage of its outburst cycle. The accretion disk dominated the ultraviolet light curve of Z Cha at the peak of an eruption; the white dwarf, the bright spot on the edge of the disk, and the boundary layer were all invisible. We were able to obtain an axisymmetric map of the accretion disk at this time only by adopting a flared disk with an opening angle of similar to 8 degrees. The run of brightness temperature with radius in the disk at the peak of the eruption was too flat to be consistent with a steady state, optically thick accretion disk. The local rate of mass flow through the disk was similar to 5 x 10(-10) M. yr(-1) near the center of the disk and similar to 5 x 10(-9) M. yr(-1) near the outer edge. The white dwarf, the accretion disk, and the boundary layer were all significant contributors to the ultraviolet flux on the descending branches of the eruptions. The temperature of the white dwarf during decline was 18,300 K < T-wd < 21,800 K, which is significantly greater than at minimum light. Six days after the maximum of an eruption Z Cha had faded to near minimum light at ultraviolet wavelengths, but was still similar to 70% brighter than at minimum light in the B band. About one-quarter of the excess flux in the B band came from the accretion disk. Thus, the accretion disk faded and became invisible at ultraviolet wavelengths before it faded at optical wavelengths. The disk did, however, remain optically thick and obscured the lower half of the white dwarf at ultraviolet and possibly at optical wavelengths for 2 weeks after the eruption ended. A bright region, which we identify with the boundary layer, was visible at the equator of the white dwarf in the B band. The upper limit to the temperature of the boundary layer is 18,200 K, and at this low temperature it was a minor contributor to the ultraviolet flux. It is possible to explain the invisibility of the boundary layer at both maximum and minimum light, while still allowing it to be visible on the descending branch of eruptions, by invoking a rapidly rotating white dwarf. The equatorial velocity of the white dwarf must be greater than similar to 0.23 times the Keplerian velocity at the surface of a spherical white dwarf. The bright spot became clearly visible at ultraviolet wavelengths immediately after the end of the eruptions. Its distance from the white dwarf and thus the radius of the accretion disk was R(D)/R(L1) similar to 0.56. The temperature of the white dwarf was somewhat elevated but was not greater than 17,500 K. By the third week after eruptions the eclipse looked like a simple occultation of an unobscured, spherical white dwarf by a dark secondary star. The center of the accretion disk was, therefore, optically thin at ultraviolet wavelengths and the boundary layer was too faint to be visible. The distance of the bright spot from the white dwarf and hence the radius of the disk decreased slowly through minimum light, reaching R(D)/R(L1) similar to 0.47 just before the first eruption and similar to 0.52 just before the second. The temperature and ultraviolet flux from the bright spot increased from the end of one eruption to the beginning of the next, its temperature reaching 16,700 +/- 600 K at the end of quiescence. The temperature of the white dwarf in quiescence was 15,700 +/- 550 K; if it is fully limb darkened, its radius was R(wd)/R(L1) = 0.0254 +/- 0.0013, and if it is not limb darkened, its radius was R(wd)/R(L1) = 0.0222 +/- 0.0013. C1 UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV WISCONSIN,SPACE ASTRON LAB,MADISON,WI 53706. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. MIT,DEPT PHYS,CAMBRIDGE,MA 02139. RP ROBINSON, EL (reprint author), UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712, USA. NR 63 TC 28 Z9 28 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 1995 VL 443 IS 1 BP 295 EP 318 DI 10.1086/175526 PN 1 PG 24 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ879 UT WOS:A1995QQ87900031 ER PT J AU WOLFF, CL AF WOLFF, CL TI OSCILLATION-CONVECTION COUPLING - CAUSE OF SUPERGRANULATION SO ASTROPHYSICAL JOURNAL LA English DT Article DE CONVECTION; HYDRODYNAMICS; SUN, GRANULATION; SUN, INTERIOR; SUN, OSCILLATIONS ID R-MODES; ROTATING STAR; SUN AB A semianalytic method is derived for dealing simultaneously with large numbers of linear stellar oscillation modes trapped in a cavity (a shell) of fluid which is rotating and convecting. A simple generalization of mixing-length theory shows how convection is modulated by weak rotational effects and by the horizontal wind fields of linear r-mode oscillations. The modulated convection is then used to compute the energy lost to turbulent viscosity by a family of nondegenerate oscillations. Viscosity terms of fourth degree in the wind shear can be included if they are a perturbation affecting only a small portion of the r-mode. Viscous energy loss strengthens convection in a narrow layer near the base of the H and He ionization zone. In the Sun, this layer is about 7 Mm thick and centered at 0.932 of a solar radius where convection cells have a typical size of about 20 Mm and a lifetime of 0.3 Ms, both similar to what is observed in supergranules. If the rms velocity of r-modes at the surface exceeds 5 m s(-1), then energy is deposited inside the Sun at a sufficient rate to power the supergranulation and impose on it a weak latitude dependence. RP WOLFF, CL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 35 TC 16 Z9 16 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 1995 VL 443 IS 1 BP 423 EP 433 DI 10.1086/175535 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ879 UT WOS:A1995QQ87900040 ER PT J AU GOODMAN, ML AF GOODMAN, ML TI HEATING OF THE SOLAR MIDDLE CHROMOSPHERE BY LARGE-SCALE ELECTRIC CURRENTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; SUN, CHROMOSPHERE ID MODEL; WAVES; ATMOSPHERE; SUN AB A global resistive, two-dimensional, time-dependent magnetohydrodynamic (MHD) model is used to introduce and support the hypothesis that the quiet solar middle chromosphere is heated by resistive dissipation of large-scale electric currents which flu most of its volume. The scale height and maximum magnitude of the current density are 400 km and 31.3 mA m(-2), respectively. The associated magnetic field is almost horizontal, has the same scale height as the current density, and has a maximum magnitude of 153 G. The current is carried by electrons flowing across magnetic field lines at 1 m s(-1). The resistivity is the electron contribution to the Pedersen resistivity for a weakly ionized, strongly magnetized, hydrogen gas. The model does not include a driving mechanism. Most of the physical quantities in the model decrease exponentially with time on a resistive timescale of 41.3 minutes. However, the initial values and spatial dependence of these quantities are expected to be essentially the same as they would be if the correct driving mechanism were included in a more general model. The heating rate per unit mass is found to be 4.5 x 10(9) ergs g(-1) s(-1), independent of height and latitude. The electron density scale height is found to be 800 km. The model predicts that 90% of the thermal energy required to heat the middle chromosphere is deposited in the height range 300-760 km above the temperature minimum. It is shown to be consistent to assume that the radiation rate per unit volume is proportional to the magnetic energy density, and it then follows that the heating rate per unit volume is also proportional to the magnetic energy density. MHD waves, bulk flow normal the magnetic field, and magnetic flux tubes emerging from the photosphere into the overlying chromosphere are briefly discussed as possible driving mechanisms for establishing and maintaining the current system. The case in which part or all of the current is carried by protons and metal ions, and the contribution of electron-proton scattering to the current are also considered, with the conclusion that these effects do not change the qualitative predictions of the model, but probably change the quantitative predictions slightly, mainly by increasing the maximum magnitude of the current density and magnetic field to at most similar to 100 mA m(-2) and similar to 484 G, respectively. The heating rate per unit mass, current density scale height, magnetic field scale height, temperatures, and pressures are unchanged or are only slightly changed by including these additional effects due to protons and ions. C1 NASA, GODDARD SPACE FLIGHT CTR, EXTRATERR PHYS LAB, PLANETARY MAGNETOSPHERES BRANCH, GREENBELT, MD 20771 USA. RP APPL RES CORP, GREENBELT, MD 20771 USA. NR 26 TC 8 Z9 8 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1995 VL 443 IS 1 BP 450 EP 459 DI 10.1086/175538 PN 1 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ879 UT WOS:A1995QQ87900043 ER PT J AU ANDERSSON, BG WANNIER, PG AF ANDERSSON, BG WANNIER, PG TI THE MAGNETIC-FIELD IN LYNDS-1457 - MULTIBAND PHOTOPOLARIMETRY SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, INDIVIDUAL (LYNDS 1457); POLARIZATION ID MOLECULAR CLOUD; POLARIZATION; MBM-12 AB We have performed multiband photopolarimetry toward stars behind the molecular cloud L1457 (MBM 12). This cloud is the nearest known molecular cloud (65 pc) and is thought to be contained within the local ''hot bubble.'' The polarization shows a regular structure, indicating that the cloud is threaded by an ordered magnetic field. The wavelength dependence of the polarization seems to indicate that the grains in L1457 have higher indices of refraction than normal for interstellar clouds. However, the wavelength of maximum polarization indicates that their size distribution is close to normal. C1 UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. RP ANDERSSON, BG (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MAIL STOP 169-506,PASADENA,CA 91109, USA. OI Andersson, B-G/0000-0001-6717-0686 NR 19 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 10 PY 1995 VL 443 IS 1 BP L49 EP L52 DI 10.1086/187833 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ885 UT WOS:A1995QQ88500013 PM 11538589 ER PT J AU REACH, WT FRANZ, BA WEILAND, JL HAUSER, MG KELSALL, TN WRIGHT, EL RAWLEY, G STEMWEDEL, SW SPIESMAN, WJ AF REACH, WT FRANZ, BA WEILAND, JL HAUSER, MG KELSALL, TN WRIGHT, EL RAWLEY, G STEMWEDEL, SW SPIESMAN, WJ TI OBSERVATIONAL CONFIRMATION OF A CIRCUMSOLAR DUST RING BY THE COBE SATELLITE SO NATURE LA English DT Article ID SOLAR-SYSTEM; ZODIACAL EMISSION; PARTICLES AB ASTEROID collisions are an important source of the dust particles in the zodiacal cloud(1-3). These particles spiral in towards the Sun under the influence of drag forces(4-6) and, in passing through the inner Solar System, are subject to gravitational perturbations by the planets, which may trap them (at least temporarily) in orbital resonances(7-10). Recently, numerical simulations have shown that resonances with the Earth are particularly effective at trapping asteroidal dust, leading to the suggestion that the Earth may be embedded in a circumsolar ring of dust(11). The azimuthal structure of this ring was predicted to be asymmetric, with the region trailing the Earth being substantially more dense than that in the leading direction(11). This prediction is in both qualitative and quantitative agreement with the asymmetry in zodiacal light observed bg the Infrared Astronomical Satellite (IRAS)(11,12), but the IRAS data alone are equivocal because of calibration uncertainties and sparse coverage of elongation angle(12). Here we report observations by the Diffuse Infrared Background Experiment(13) (DIRBE) on the Cosmic Background Explorer satellite (COBE)(14), which confirm both the existence of this ring and the predictions of its near-Earth structure. C1 NASA,GODDARD SPACE FLIGHT CTR,APPL RES CORP,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,GEN SCI CORP,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,DEPT ASTRON,LOS ANGELES,CA 90024. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. RP REACH, WT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,CODE 685,GREENBELT,MD 20771, USA. RI Reach, William/C-4710-2008; Franz, Bryan/D-6284-2012; OI Franz, Bryan/0000-0003-0293-2082; Reach, William/0000-0001-8362-4094 NR 21 TC 105 Z9 105 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 6 PY 1995 VL 374 IS 6522 BP 521 EP 523 DI 10.1038/374521a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QR069 UT WOS:A1995QR06900044 ER PT J AU RYAN, MA AF RYAN, MA TI CHEMISTRY IN A RESEARCH-INSTITUTE - A HAPPY COMBINATION OF INDUSTRY AND ACADEMIA SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 JET PROP LAB,ELECT POWER SECT,PASADENA,CA 91109. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 12 EP SCHB PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301870 ER PT J AU RICCA, A BAUSCHLICHER, CW AF RICCA, A BAUSCHLICHER, CW TI A COMPARISON OF DENSITY-FUNCTIONAL THEORY WITH AB-INITIO METHODS FOR 1ST ROW TRANSITION-METALS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 61 EP COMP PN 1 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP232 UT WOS:A1995QP23201822 ER PT J AU GONTHIER, PL CHURCH, E GELFORD, B LORENZ, WA HARDING, AK AF GONTHIER, PL CHURCH, E GELFORD, B LORENZ, WA HARDING, AK TI GENERAL-RELATIVISTIC CORRECTIONS IN THE GAMMA-RAY EMISSION FROM PULSARS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 HOPE COLL,DEPT PHYS,HOLLAND,MI 49422. NASA,GODDARD SPACE FLIGHT CTR,LHEA,GREENBELT,MD 20771. RI Harding, Alice/D-3160-2012 NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 77 EP NUCL PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23300077 ER PT J AU BAUSCHLICHER, CW RICCA, A PARTRIDGE, H LANGHOFF, SR AF BAUSCHLICHER, CW RICCA, A PARTRIDGE, H LANGHOFF, SR TI THE BONDING AND SPECTROSCOPY OF METAL DIMERS 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 PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 78 EP PHYS PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23300833 ER PT J AU KNUDSEN, RL JENSEN, BJ AF KNUDSEN, RL JENSEN, BJ TI BLENDS OF REACTIVE DILUENTS WITH PHENYLETHYL TERMINATED ARYLENE ETHER OLIGOMERS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 79 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301215 ER PT J AU PERRY, JW MANSOUR, K MILES, P CHEN, CT MARDER, SR KWAG, G KENNEY, M AF PERRY, JW MANSOUR, K MILES, P CHEN, CT MARDER, SR KWAG, G KENNEY, M TI PHTHALOCYANINE MATERIALS FOR OPTICAL LIMITING SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 JET PROP LAB,PASADENA,CA 91109. CALTECH,BECKMAN INST,PASADENA,CA 91125. LOGICON RDA,LOS ANGELES,CA 90009. CASE WESTERN RESERVE UNIV,DEPT CHEM,CLEVELAND,OH 44106. RI Kenney, Malcolm/C-6101-2011; Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 0 TC 1 Z9 1 U1 0 U2 3 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 131 EP PMSE PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301657 ER PT J AU GOLUB, MA WYDEVEN, T FINNEY, LS AF GOLUB, MA WYDEVEN, T FINNEY, LS TI PLASMA COPOLYMERIZATION OF TETRAFLUOROETHYLENE AND CHLOROTRIFLUOROETHYLENE SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 SURFACE SCI LABS,MT VIEW,CA 94043. NASA,AMES RES CTR,BIONET CORP,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 166 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301302 ER PT J AU JAFFE, RL SMITH, GD AF JAFFE, RL SMITH, GD TI QUANTUM-CHEMISTRY DERIVED FORCE-FIELDS FOR SIMULATIONS OF AROMATIC POLYMERS IN THE SOLID AND MELT STATES SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 203 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301339 ER PT J AU MINER, GA STCLAIR, AK STOAKLEY, DM CAPLAN, ML KALIL, CR BROWN, CA SHIPULKSI, EM AF MINER, GA STCLAIR, AK STOAKLEY, DM CAPLAN, ML KALIL, CR BROWN, CA SHIPULKSI, EM TI SURFACE-ANALYSIS OF SELF-METALLIZING POLYIMIDE FILMS FOR SPACE APPLICATIONS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 205 EP PMSE PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301731 ER PT J AU ROBERTS, MJ MEADOR, MA DURAN, RS AF ROBERTS, MJ MEADOR, MA DURAN, RS TI LANGMUIR BLODGETT-KUHN FILMS OF A LIQUID-CRYSTALLINE PHENYLACETYLENE SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 UNIV FLORIDA,DEPT CHEM,CTR MACROMOLEC SCI & ENGN,GAINESVILLE,FL 32611. NASA,LEWIS RES CTR,DIV MAT,CLEVELAND,OH 44135. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 244 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301380 ER PT J AU MARDER, SR AF MARDER, SR TI DESIGN OF CHROMOPHORES FOR 2ND-ORDER NONLINEAR-OPTICAL APPLICATIONS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 CALTECH,BECKMAN INST,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 331 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301467 ER PT J AU YOON, DY SMITH, GD JAFFE, RL ZHU, W EDIGER, MD AF YOON, DY SMITH, GD JAFFE, RL ZHU, W EDIGER, MD TI COMPARISON OF SIMULATIONS AND EXPERIMENTS ON EQUILIBRIUM AND DYNAMIC PROPERTIES OF POLYMETHYLENE AND POLYOXYETHYLENE CHAIN IN THE MELTS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 UNIV WISCONSIN,MADISON,WI 53706. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. IBM CORP,ALMADEN RES CTR,SAN JOSE,CA 95120. THERMOSCI INST,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 356 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301492 ER PT J AU SMITH, GD JAFFE, RL AF SMITH, GD JAFFE, RL TI CONDENSED-PHASE EFFECTS IN POLYETHYLENE OXIDE SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 359 EP POLY PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23301495 ER PT J AU BEDWORTH, PV MARDER, SR BOURHILL, G PERRY, JW JEN, AKY AF BEDWORTH, PV MARDER, SR BOURHILL, G PERRY, JW JEN, AKY TI BITHIOPHENE CHROMOPHORES FOR NONLINEAR-OPTICAL APPLICATIONS SO ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY LA English DT Meeting Abstract C1 ENICHEM AMER INC,CTR RES & DEV,MONMOUTH JCT,NJ 08852. CALTECH,BECKMAN INST,PASADENA,CA 91125. JET PROP LAB,PASADENA,CA 91109. RI Perry, Joseph/B-7191-2011 OI Perry, Joseph/0000-0003-1101-7337 NR 0 TC 0 Z9 0 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0065-7727 J9 ABSTR PAP AM CHEM S JI Abstr. Pap. Am. Chem. Soc. PD APR 2 PY 1995 VL 209 BP 386 EP ORGN PN 2 PG 0 WC Chemistry, Multidisciplinary SC Chemistry GA QP233 UT WOS:A1995QP23300504 ER PT J AU TAYLOR, RL BORDI, F AF TAYLOR, RL BORDI, F TI A SPACECRAFT FOR THE EARTH OBSERVING SYSTEM SO ACTA ASTRONAUTICA LA English DT Article AB The space segment of NASA's Earth observing system, (EOS) includes three series of intermediate-sized spacecraft, plus two smaller spacecraft. The EOS-AM spacecraft is the first of the intermediate-sized spacecraft. EOS-AM accommodates sensors that measure cloud and aerosol radiative properties, and that provide data to study the water and energy cycles. Scheduled for launch in the late 1990s, the EOS-AM spacecraft is designed for a 5-year mission. The spacecraft will be launched from the Western Space and Missile Center (California) into a polar, Sun-synchronous, low-Earth orbit with a 16-day repeat cycle. In its flight configuration, the spacecraft is almost 20 ft long (including instruments mounted at the fore end of the spacecraft) and 6 ft wide (in its widest dimension), has a mass of about 13,000 Ibs and uses about 3000 W of electrical power. The spacecraft is compatible with the Atlas IIAS launch vehicle. EOS-AM has on-board storage for at least two orbits of science data. These data will be transmitted to the ground via the tracking and data relay satellite system (using data structures and protocols in compliance with the recommendations of the Consultative Committee for Space Data Systems). A direct downlink system to support distributed users will also be available. RP TAYLOR, RL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 421,GREENBELT,MD 20771, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-5765 J9 ACTA ASTRONAUT JI Acta Astronaut. PD APR PY 1995 VL 35 IS 7 BP 437 EP 443 DI 10.1016/0094-5765(94)00277-S PG 7 WC Engineering, Aerospace SC Engineering GA QX381 UT WOS:A1995QX38100003 ER PT J AU GIBBONS, RC AF GIBBONS, RC TI POTENTIAL FUTURE APPLICATIONS FOR THE TRACKING AND DATA RELAY SATELLITE-II (TDRS-II) SYSTEM SO ACTA ASTRONAUTICA LA English DT Article AB During the conceptual design phases of the tracking and data relay satellite (TDRS) II system provision was made for a future service growth (FSG) payload with an undefined mission. The intent of the FSG was to provide a resource for TDRS II applications which would be available to meet a change in requirements for the operational TDRS II system. This paper summarizes the effect of the consideration of potential FSG applications imposed on the tracking and data relay satellite (TDRS) II system. The following applications were considered as FSG candidates: An optical 650 Mbps space-to-space link (SSL) coupled to an optical or RF downlink [1] An RF or optical crosslink to extend the baseline TDRS II system coverage -zone of exclusion (ZOE) closure [1] Relay for lunar communications either RF or optically Relay for Martian communications either RF or optically This paper summarizes work done in the 1990 time frame on the above stated applications. Since then, NASA has sponsored several studies (during phase B of the TDRS II development cycle) of the ZOE closure application of the FSG. The purpose of this paper is to report on the efforts previously considered for the FSG. A previous paper was presented at the 1991 Congress related to the second application above. This paper extends this effort to the four stated applications. RP GIBBONS, RC (reprint author), MITRE CORP,NASA HEADQUARTERS,409 THIRD ST SW,SUITE 300,WASHINGTON,DC 20024, 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 APR PY 1995 VL 35 IS 8 BP 537 EP 545 DI 10.1016/0094-5765(94)00285-T PG 9 WC Engineering, Aerospace SC Engineering GA RB826 UT WOS:A1995RB82600005 ER PT J AU BAKER I XIAO, H KLEIN, O NELSON, C WHITTENBERGER, JD AF BAKER, I XIAO, H KLEIN, O NELSON, C WHITTENBERGER, JD TI THE EFFECT OF TEMPERATURE AND FE-AL RATIO ON THE FLOW AND FRACTURE OF FEAL SO ACTA METALLURGICA ET MATERIALIA LA English DT Article ID ROOM-TEMPERATURE; BETA-CUZN; CLIMB DISSOCIATION; SLIP DIRECTIONS; ALLOYS; DEFORMATION; STRENGTH; DISLOCATIONS; CRYSTAL; EMBRITTLEMENT AB Mechanical testing of large-grained binary FeAl alloys as a function of temperature showed that the yield stress decreased rapidly from 77 to 300 K, followed by a slower decrease up to 500 K. For iron-rich alloys (less than or equal to 45 at.% Al), the yield stress exhibited a valley at similar to 500 K and a peak at similar to 675 K before declining rapidly at higher temperatures. The stoichiometric alloy showed the highest yield stress at all temperatures. The ductility of the off-stoichiometric alloys in vacuum increased with increasing temperature until at 900 K elongations up to similar to 150% were obtained; the reduction in area showed a sharp transition from < 10% below 500 K to > 80% above 600 K. All off-stoichiometric alloys displayed a mixture of intergranular fracture plus transgranular cleavage below 600 K; the amount of cleavage increased with both decreasing iron concentration and increasing temperature. At temperature greater than or equal to 600 K the fracture mode changed to ductile rupture. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44070 USA. RP BAKER I (reprint author), DARTMOUTH COLL, THAYER SCH ENGN, HANOVER, NH 03755 USA. NR 53 TC 48 Z9 48 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0956-7151 J9 ACTA METALL MATER JI Acta Metall. Mater. PD APR PY 1995 VL 43 IS 4 BP 1723 EP 1730 DI 10.1016/0956-7151(94)00369-S PG 8 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA QN758 UT WOS:A1995QN75800041 ER PT J AU WILCZYNSKI, H ASAKIMORI, K BURNETT, TH CHERRY, ML CHRISTL, MJ DAKE, S DERRICKSON, JH FOUNTAIN, WF FUKI, M GREGORY, JC HAYASHI, T HOLYNSKI, R IWAI, J IYONO, A JONES, WV LORD, JJ MIYAMURA, O ODA, H OGATA, T OLSON, ED PARNELL, TA ROBERTS, FE STRAUSZ, SC TAKAHASHI, Y TOMINAGA, T WATTS, JW WEFEL, JP WILBER, M WILCZYNSKA, B WILKES, RJ WOLTER, W ZAGER, EL AF WILCZYNSKI, H ASAKIMORI, K BURNETT, TH CHERRY, ML CHRISTL, MJ DAKE, S DERRICKSON, JH FOUNTAIN, WF FUKI, M GREGORY, JC HAYASHI, T HOLYNSKI, R IWAI, J IYONO, A JONES, WV LORD, JJ MIYAMURA, O ODA, H OGATA, T OLSON, ED PARNELL, TA ROBERTS, FE STRAUSZ, SC TAKAHASHI, Y TOMINAGA, T WATTS, JW WEFEL, JP WILBER, M WILCZYNSKA, B WILKES, RJ WOLTER, W ZAGER, EL TI MULTIPHOTON DECAYS OF HEAVY-PARTICLES SO ACTA PHYSICA POLONICA B LA English DT Article; Proceedings Paper CT Cracow Epiphany Conference on Heavy Quarks, to Honour the 60th Birthday of Kacper Zalewski CY JAN 05-06, 1995 CL KRAKOW, POLAND ID ENERGY AB Decays of two heavy particles, produced in cosmic ray interactions, are presented. These particles decay into one charged particle and four photons each. The photons converted into electron pairs very close to the decay vertex. Attempts to explain this decay topology with known particle decays are presented. Unless both events represent a b --> u transition, which is statistically unlikely, then other known decay modes for charmed or bottom particles do not account satisfactorily for these observations. This could indicate, possibly, a new decay channel. C1 KOBE WOMENS JR COLL,KOBE,JAPAN. UNIV WASHINGTON,SEATTLE,WA 98195. LOUISIANA STATE UNIV,BATON ROUGE,LA 70803. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. KOBE UNIV,KOBE 657,JAPAN. KOCHI UNIV,KOCHI 780,JAPAN. UNIV ALABAMA,HUNTSVILLE,AL 35899. UNIV TOKYO,INST COSM RAY RES,TOKYO,JAPAN. OKAYAMA UNIV SCI,OKAYAMA 700,JAPAN. HIROSHIMA UNIV,HIROSHIMA,JAPAN. RP WILCZYNSKI, H (reprint author), INST NUCL PHYS,KAWIORY 26A,PL-30055 KRAKOW,POLAND. RI Wilkes, R.Jeffrey/E-6011-2013 NR 10 TC 0 Z9 0 U1 0 U2 0 PU POLISH ACAD SCIENCES INST PHYSICS PI WARSAW PA AL LOTNIKOW 32-46, 02-668 WARSAW, POLAND SN 0587-4254 J9 ACTA PHYS POL B JI Acta Phys. Pol. B PD APR PY 1995 VL 26 IS 4 BP 861 EP 872 PG 12 WC Physics, Multidisciplinary SC Physics GA QZ659 UT WOS:A1995QZ65900015 ER PT J AU HOLLOWAY, H AF HOLLOWAY, H TI LIFE WITHOUT BOUNDARIES SO AEROSPACE AMERICA LA English DT Editorial Material RP HOLLOWAY, H (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD APR PY 1995 VL 33 IS 4 BP 3 EP 3 PG 1 WC Engineering, Aerospace SC Engineering GA QR278 UT WOS:A1995QR27800001 ER PT J AU WILLIAMS, LJ AF WILLIAMS, LJ TI HSCT RESEARCH GATHERS SPEED SO AEROSPACE AMERICA LA English DT Article RP WILLIAMS, LJ (reprint author), NASA,HIGH SPEED RES DIV,WASHINGTON,DC 20546, USA. NR 0 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 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD APR PY 1995 VL 33 IS 4 BP 32 EP 37 PG 6 WC Engineering, Aerospace SC Engineering GA QR278 UT WOS:A1995QR27800013 ER PT J AU SHEN, YS AF SHEN, YS TI SIR-C - ADVANCE IMAGING RADAR STUDIES THE EARTH SO AEROSPACE AMERICA LA English DT Article RP SHEN, YS (reprint author), JET PROP LAB,NASA,SIR C RADAR INSTRUMENT GRP,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 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD APR PY 1995 VL 33 IS 4 BP 38 EP 43 PG 6 WC Engineering, Aerospace SC Engineering GA QR278 UT WOS:A1995QR27800014 ER PT J AU MCGREEVY, JL BAYLISS, A MAESTRELLO, L AF MCGREEVY, JL BAYLISS, A MAESTRELLO, L TI INTERACTION OF JET NOISE WITH A NEARBY PANEL ASSEMBLY SO AIAA JOURNAL LA English DT Article ID INSTABILITIES; LAYERS; FLOWS AB A model of the interaction of the noise from a spreading subsonic jet with a panel-stringer assembly is studied numerically in two dimensions. The radiation resulting from this flow/acoustic/structure coupling is computed and analyzed in both the time and frequency domains. The jet is initially excited by a pulse-like source inserted into the flowfield. The pulse triggers instabilities associated with the inviscid instability of the jet mean flow shear layer. These instabilities in turn generate sound which provides the primary loading for the panels. The resulting structural vibration and radiation depends strongly on panel placement relative to the jet/nozzle configuration. Results are obtained for the panel responses as well as the transmitted and incident pressure. The effect of the panels is to act as a narrow filter, converting the relatively broadband forcing, heavily influenced by jet instabilities, into radiation concentrated in narrow spectral bands. C1 NORTHWESTERN UNIV,DEPT ENGN SCI & APPL MATH,EVANSTON,IL 60208. NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP MCGREEVY, JL (reprint author), PHILADELPHIA COLL PHARM & SCI,DEPT MATH & PHYS,PHILADELPHIA,PA 19104, USA. RI Bayliss, Alvin/B-7337-2009 NR 30 TC 4 Z9 4 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 APR PY 1995 VL 33 IS 4 BP 577 EP 585 DI 10.2514/3.12618 PG 9 WC Engineering, Aerospace SC Engineering GA QT118 UT WOS:A1995QT11800001 ER PT J AU CEBECI, T HEFAZI, H ROKNALDIN, F CARR, LW AF CEBECI, T HEFAZI, H ROKNALDIN, F CARR, LW TI PREDICTING STALL AND POST-STALL BEHAVIOR OF AIRFOILS AT LOW MACH NUMBERS SO AIAA JOURNAL LA English DT Article AB An interactive boundary-layer method, together with the e(n) approach to the calculation of transition, is used to predict the stall and post-stall behavior of airfoils in incompressible and compressible flows at low freestream Mach numbers. Two separate inviscid methods-a panel method with compressibility corrections and a full potential method-are used to compute the external velocity distribution needed in the solution of the compressible boundary-layer equations. The turbulence model is based on the Cebeci-Smith algebraic eddy-viscosity formulation with improvements for strong pressure gradient effects. Comparison of calculated results with inviscid flow computed with a panel method indicate excellent agreement with experiment for a wide range of Reynolds numbers in incompressible flows. Comparison of calculated results obtained with inviscid how computed with a full potential method also indicate excellent agreement with experiment for a wide range of angles of attack, including stall for compressible flows at low freestream Mach numbers. The study also shows that even though the compressibility corrections to the panel method are adequate at small-to-moderate angles of attack, they are not satisfactory at higher angles of attack, especially near stall. C1 NASA,AMES RES CTR,USA ATCOM,AEROFLIGHTDYNAM DIRECTORATE,MOFFETT FIELD,CA 94035. NASA,AMES RES CTR,FLUID MECH LAB BRANCH,MOFFETT FIELD,CA 94035. RP CEBECI, T (reprint author), CALIF STATE UNIV LONG BEACH,DEPT AEROSP ENGN,LONG BEACH,CA 90840, USA. OI Hefazi, Hamid/0000-0003-4267-2123 NR 23 TC 6 Z9 6 U1 1 U2 5 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 1995 VL 33 IS 4 BP 595 EP 602 DI 10.2514/3.12391 PG 8 WC Engineering, Aerospace SC Engineering GA QT118 UT WOS:A1995QT11800003 ER PT J AU VENKATAKRISHNAN, V MAVRIPLIS, DJ AF VENKATAKRISHNAN, V MAVRIPLIS, DJ TI AGGLOMERATION MULTIGRID FOR THE 3-DIMENSIONAL EULER EQUATIONS SO AIAA JOURNAL LA English DT Article AB A multigrid procedure that makes use of coarse grids generated by the agglomeration of control volumes is advocated as a practical approach for solving the three-dimensional Euler equations on unstructured grids about complex configurations. It is shown that the agglomeration procedure can be tailored to achieve certain coarse grid properties such as the sizes of the coarse grids and aspect ratios of the coarse grid cells. The agglomeration is done as a preprocessing step and runs in linear time. The implications for multigrid of using arbitrary polyhedral coarse grids are discussed. The agglomeration multigrid technique compares very favorably with existing multigrid procedures both in terms of convergence rates and elapsed times. The main advantage of the present approach is the ease with which coarse grids of any desired degree of coarseness may be generated in three dimensions, without being constrained by considerations of geometry. Inviscid flows over a variety of complex configurations are computed using the agglomeration multigrid strategy. RP VENKATAKRISHNAN, V (reprint author), NASA,LANGLEY RES CTR,INST COMP APPL SCI & ENGN,HAMPTON,VA 23681, USA. NR 18 TC 23 Z9 24 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 1995 VL 33 IS 4 BP 633 EP 640 DI 10.2514/3.12625 PG 8 WC Engineering, Aerospace SC Engineering GA QT118 UT WOS:A1995QT11800008 ER PT J AU LEE, G MCCOY, BJ SMITH, JM CAGLIOSTRO, DE AF LEE, G MCCOY, BJ SMITH, JM CAGLIOSTRO, DE TI GRADED DEPOSITION BY CHEMICAL-VAPOR INFILTRATION OF WOVEN FABRICS SO AICHE JOURNAL LA English DT Note ID CERAMIC COMPOSITES C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP LEE, G (reprint author), UNIV CALIF DAVIS,DEPT CHEM ENGN & MAT SCI,DAVIS,CA 95616, USA. NR 5 TC 1 Z9 2 U1 0 U2 0 PU AMER INST CHEMICAL ENGINEERS PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0001-1541 J9 AICHE J JI AICHE J. PD APR PY 1995 VL 41 IS 4 BP 1037 EP 1040 DI 10.1002/aic.690410435 PG 4 WC Engineering, Chemical SC Engineering GA QT338 UT WOS:A1995QT33800034 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 LOADING RIGHT ATRIAL AND VENTRICULAR RECEPTORS ON STIMULATED AVP, ACTH, AND RENIN SECRETION IN AWAKE DOGS SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE BLOOD PRESSURE; CARDIAC RECEPTORS; ARTERIAL BARORECEPTORS; ANTIDIURETIC HORMONE; CORTISOL ID CONSCIOUS DOGS; NATRIURETIC PEPTIDES; ARTERIAL-HYPOTENSION; PLASMA VASOPRESSIN; PRESSURE; STRETCH; RELEASE; RADIOIMMUNOASSAY; INHIBITION; MECHANISM AB The goal of this study was to test the hypothesis that increasing or decreasing the load on baroreceptors in the right heart influenced the secretion of arginine vasopressin (AVP), adrenocorticotropic hormone (ACTH), and renin during a state of sustained arterial hypotension. The hypothesis was tested in chronically instrumented conscious dogs prepared with inflatable cuffs around the pulmonary artery (PA) and the thoracic inferior vena cava (IVC). In one protocol (n = 5), mean arterial pressure was reduced 10 or 20% below control by constriction of the PA, a maneuver that caused a fall in left atrial pressure (LAP) and an increase in right atrial pressure (RAP). Plasma AVP, ACTH, atrial natriuretic peptide (ANP), and plasma renin activity (PRA) all increased (P < 0.05) in response to constriction of the PA. Reducing RAP to control by constriction of the IVC during maintained constriction of the PA had no effect on MAP, LAP, plasma AVP, ACTH, or PRA, but plasma ANP fell significantly. In a separate protocol (n = 4), constriction of the IVC was used to reduce MAP 10 or 20% below control, and this led to significant decreases in both LAP and RAP and increases in plasma AVP, ACTH, and PRA. RAP was then increased above control by constriction of the PA without altering either MAP or LAP. Raising RAP from a level that was 6.3 +/- 1.3 mmHg below control to 3.5 +/- 1.0 mmHg above control had no effect on plasma AVP, ACTH, or PRA. These results show that, against constant reductions in MAP and LAP, acute changes in RAP over a 9-mmHg range have no effect on plasma AVP, ACTH, or PRA. Therefore, in contrast to the potent inhibitory effect of loading left atrial receptors on secretion of AVP, ACTH, and renin, we conclude that baroreceptors on the right. side of the heart have minimal influence on the secretion of AVP, ACTH, and renin in conscious dogs. C1 UNIV CALIF SAN FRANCISCO, SCH MED, DEPT PHYSIOL, SAN FRANCISCO, CA 94143 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. FU NHLBI NIH HHS [HL-41156] NR 28 TC 6 Z9 6 U1 1 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0363-6119 J9 AM J PHYSIOL-REG I JI Am. J. Physiol.-Regulat. Integr. Compar. Physiol. PD APR PY 1995 VL 268 IS 4 BP R1069 EP R1077 PG 9 WC Physiology SC Physiology GA QR993 UT WOS:A1995QR99300031 PM 7733389 ER PT J AU MCKEEVER, KH KEIL, LC SANDLER, H AF MCKEEVER, KH KEIL, LC SANDLER, H TI INTRAPERICARDIAL DENERVATION - RESPONSES TO WATER IMMERSION IN RHESUS-MONKEYS SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE WATER IMMERSION; NATRIURESIS; VASOPRESSIN; CARDIAC DENERVATION; MONKEY ID PRIMATE MACACA-FASCICULARIS; ATRIAL-NATRIURETIC-PEPTIDE; HEAD-OUT IMMERSION; PLASMA VASOPRESSIN; RENAL RESPONSES; VOLUME EXPANSION; LOW-PRESSURE; HUMANS; SUPPRESSION; RATS AB Eleven anesthetized rhesus monkeys were used to study cardiovascular, renal, and endocrine alterations associated with 120 min of head-out water immersion. Five animals underwent complete intrapericardial denervation using the Randall technique, while the remaining six monkeys served as intact controls. Each animal was chronically instrumented with an electromagnetic flow probe on the ascending aorta, a strain gauge pressure transducer implanted in the apex of the left. ventricle (LV), and electrocardiogram leads anchored to the chest wall and LV. During immersion, LV end-diastolic pressure, urine flow, glomerular filtration rate, sodium excretion, and circulating atrial natriuretic peptide (ANP) each increased (P < 0.05) for intact and denervated monkeys. There were no alterations in free water clearance in either group during immersion, yet fractional excretion of free water increased (P < 0.05) in the intact monkeys. Plasma renin activity (PRA) decreased (P < 0.05) during immersion in intact monkeys but not the denervated animals. Plasma vasopressin (PVP) concentration decreased (P < 0.05) during the first 30 min of immersion in both groups but was not distinguishable from control by 60 min of immersion in denervated monkeys. These data demonstrate that complete cardiac denervation does not block the rise in plasma ANP or prevent the natriuresis associated with head-out water immersion. The suppression of PVP during the first minutes of immersion after complete cardiac denervation suggests that extracardiac sensing mechanisms associated with the induced fluid shifts may be responsible for the findings. C1 OHIO STATE UNIV, COLL VET MED, COLUMBUS, OH 43210 USA. NASA, AMES RES CTR, CARDIOVASC RES LAB, MOFFETT FIELD, CA 94035 USA. NR 43 TC 3 Z9 3 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0363-6119 J9 AM J PHYSIOL-REG I JI Am. J. Physiol.-Regulat. Integr. Compar. Physiol. PD APR PY 1995 VL 268 IS 4 BP R1040 EP R1049 PG 10 WC Physiology SC Physiology GA QR993 UT WOS:A1995QR99300028 ER PT J AU NOVAK, G JARRETT, T AF NOVAK, G JARRETT, T TI TECHNIQUE FOR ACCURATE STELLAR POLARIMETRY USING CCD CAMERAS SO APPLIED OPTICS LA English DT Article DE POLARIZATION; CCD DETECTORS; ASTRONOMY ID INTERSTELLAR POLARIZATION; JET AB Using a technique for CCD polarimetry, we have obtained stellar polarization data with the 0.9-m telescope on Kitt Peak and with the Tek 2048 CCD camera. Measurements of stars viewed through holes in polarizing filters serve to correct for variations in atmospheric transparency. For the brightest stars the uncertainties in the measured polarization during a single, hour-long, polarimetric sequence are 0.3-0.5%, because of the residual effects of the variations in transparency. For fainter stars we are Poisson noise limited. Our technique provides some advantages over other techniques for CCD polarimetry, primarily because it can be easily integrated into existing photometric systems. C1 CALTECH,JET PROP LAB,CTR INFRARED PROC & ANAL,PASADENA,CA 91125. RP NOVAK, G (reprint author), NORTHWESTERN UNIV,DEPT PHYS & ASTRON,EVANSTON,IL 60208, USA. NR 25 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 APR 1 PY 1995 VL 34 IS 10 BP 1672 EP 1677 PG 6 WC Optics SC Optics GA QP649 UT WOS:A1995QP64900006 PM 21037710 ER PT J AU WINKER, DM POOLE, LR AF WINKER, DM POOLE, LR TI MONTE-CARLO CALCULATIONS OF CLOUD RETURNS FOR GROUND-BASED AND SPACE-BASED LIDARS SO APPLIED PHYSICS B-LASERS AND OPTICS LA English DT Article; Proceedings Paper CT 6th MUltiple SCattering LIDAR Experiments Workshop CY JAN 26-28, 1993 CL NEUCHATEL, SWITZERLAND AB A Monte-Carlo model is described which has been developed for calculation of multiply scattered LIDAR returns. Results are shown for the common problem selected by the MUSCLE (MUltiple SCattering LIDAR Experiments) group for intercomparison, which represents a typical ground-based cloud-sensing scenario. This is contrasted with returns from the same cloud sensed by a space-based LIDAR, where multiple-scattering effects are much greater. The magnitude of multiple-scattering effects is seen to be largely determined by the optical depth across the receiver field of view at the cloud. RP WINKER, DM (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23681, USA. NR 9 TC 27 Z9 32 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0946-2171 J9 APPL PHYS B-LASERS O JI Appl. Phys. B-Lasers Opt. PD APR PY 1995 VL 60 IS 4 BP 341 EP 344 DI 10.1007/BF01082269 PG 4 WC Optics; Physics, Applied SC Optics; Physics GA QR567 UT WOS:A1995QR56700006 ER PT J AU BISSONNETTE, LR BRUSCAGLIONI, P ISMAELLI, A ZACCANTI, G COHEN, A BENAYAHU, Y KLEIMAN, M EGERT, S FLESIA, C SCHWENDIMANN, P STARKOV, AV NOORMOHAMMADIAN, M OPPEL, UG WINKER, DM ZEGE, EP KATSEV, IL POLONSKY, IN AF BISSONNETTE, LR BRUSCAGLIONI, P ISMAELLI, A ZACCANTI, G COHEN, A BENAYAHU, Y KLEIMAN, M EGERT, S FLESIA, C SCHWENDIMANN, P STARKOV, AV NOORMOHAMMADIAN, M OPPEL, UG WINKER, DM ZEGE, EP KATSEV, IL POLONSKY, IN TI LIDAR MULTIPLE-SCATTERING FROM CLOUDS SO APPLIED PHYSICS B-LASERS AND OPTICS LA English DT Article; Proceedings Paper CT 6th MUltiple SCattering LIDAR Experiments Workshop CY JAN 26-28, 1993 CL NEUCHATEL, SWITZERLAND ID LASER BACKSCATTERING; TURBID MEDIUM; FALLING SNOW; TRANSMISSION; PROPAGATION; EXTINCTION; RAIN; FOG AB Multiple-scattering LIDAR return calculations obtained by seven different models for the same specified numerical experiment are compared. This work results from an international joint effort stimulated by the workshop group called MUSCLE for MUltiple SCattering Lidar Experiments. The models include approximations to the radiative-transfer theory, Monte-Carlo calculations, a stochastic model of the process of multiple scattering, and an extension of Mie theory for particles illuminated by direct and scattered light. The model solutions are similar in form but differ by up to a factor of 5 in the strength of the multiple-scattering contributions. Various reasons for the observed differences are explored and their practical significance is discussed. C1 UNIV FLORENCE,DIPARTIMENTO FIS,I-50139 FLORENCE,ITALY. HEBREW UNIV JERUSALEM,DEPT ATMOSPHER SCI,JERUSALEM,ISRAEL. SOREQ NUCL RES CTR,IL-70600 YAVNE,ISRAEL. ISRAEL INST BIOL RES,IL-70450 NESS ZIONA,ISRAEL. UNIV GENEVA,APPL PHYS GRP,CH-1211 GENEVA 4,SWITZERLAND. SYST ANAL DIV,DEF PROCUREMENT & TECHNOL GRP,CH-3000 BERN,SWITZERLAND. RUSSIAN ACAD SCI,CTR COMP,NOVOSIBIRSK 630090,RUSSIA. UNIV MUNICH,INST MATH,D-80333 MUNICH,GERMANY. NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23666. BYELARUSSIAN ACAD SCI,INST PHYS,MINSK 220602,BYELARUS. RP BISSONNETTE, LR (reprint author), DREV,POB 8800,COURCELETTE,PQ G0A 1R0,CANADA. NR 43 TC 72 Z9 76 U1 0 U2 4 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0946-2171 J9 APPL PHYS B-LASERS O JI Appl. Phys. B-Lasers Opt. PD APR PY 1995 VL 60 IS 4 BP 355 EP 362 DI 10.1007/BF01082271 PG 8 WC Optics; Physics, Applied SC Optics; Physics GA QR567 UT WOS:A1995QR56700008 ER PT J AU MADORE, BF FREEDMAN, WL AF MADORE, BF FREEDMAN, WL TI THE TIP OF THE RED GIANT BRANCH AS A DISTANCE INDICATOR FOR RESOLVED GALAXIES .2. COMPUTER-SIMULATIONS SO ASTRONOMICAL JOURNAL LA English DT Article ID NGC-3109 C1 CARNEGIE INST WASHINGTON,OBSERV,PASADENA,CA 91101. RP MADORE, BF (reprint author), CALTECH,CTR INFRARED PROC & ANAL,NASA,IPAC EXTRAGALACT DATABASE,PASADENA,CA 91125, USA. NR 7 TC 97 Z9 99 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 1995 VL 109 IS 4 BP 1645 EP 1652 DI 10.1086/117391 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QP655 UT WOS:A1995QP65500019 ER PT J AU BERTOTTI, B AMBROSINI, R ARMSTRONG, JW ASMAR, SW COMORETTO, G GIAMPIERI, G IESS, L KOYAMA, Y MESSERI, A VECCHIO, A WAHLQUIST, HD AF BERTOTTI, B AMBROSINI, R ARMSTRONG, JW ASMAR, SW COMORETTO, G GIAMPIERI, G IESS, L KOYAMA, Y MESSERI, A VECCHIO, A WAHLQUIST, HD TI SEARCH FOR GRAVITATIONAL-WAVE TRAINS WITH THE SPACECRAFT ULYSSES SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE GRAVITATION; GALAXIES, NUCLEI ID CENTRAL BLACK-HOLES; COALESCING BINARIES; DOPPLER TRACKING; RADIATION; GALAXIES AB We report on the search for periodic gravitational wave in the mHz band conducted with the spacecraft ULYSSES. Gravitational wave signals generally provide information about the distance of the source; ULYSSES' data have a ''ken'' for each kind of source one looks for; for binaries the galactic centre is accessible to our experiment. The Neyman Pearson method, with its two strategies of 'attempting detection' and getting a threshold for no detection, is carefully discussed. We did not find significant evidence for positive detection, but established, at the 90% confidence level, upper limits to the amplitude significantly better than previous work. The weaker condition SNR = 1 corresponds to signal amplitudes h which vary about from 3 10(-15) to 10(-15) from low to high frequencies. Similar results and thresholds have been obtained for chirped signals in the linear regime with a search in the plane spanned by the frequency f and its rate of increase beta. We have discussed these limits in relation to a possible, conventional binary system of black holes in the galactic centre as a source. We have found that the data are significant only in a small region of the plane (f, beta), where limits to the mass of the companion of a central black hole of 2 10(6) M. can be established. At SNR = 1 the limit is approximate to 6000 M.. C1 CNR, IST RADIOASTRON, I-40126 BOLOGNA, ITALY. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. OSSERV ASTROFIS ARCETRI, I-50125 FLORENCE, ITALY. UNIV ROMA LA SAPIENZA, DIPARTIMENTO INGN AEROSPAZIALE, I-00158 ROME, ITALY. CNR, IST FIS SPAZIO INTERPLANETARIO, I-00044 FRASCATI, ITALY. KASHIMA SPACE RES CTR, COMMUN RES LAB, KASHIMA 314, JAPAN. RP BERTOTTI, B (reprint author), UNIV PAVIA, DIPARTIMENTO FIS NUCL & TEOR, I-27100 PAVIA, ITALY. RI Comoretto, Giovanni/F-6854-2010; IESS, Luciano/F-4902-2011; Vecchio, Alberto/F-8310-2015 OI IESS, Luciano/0000-0002-6230-5825; Vecchio, Alberto/0000-0002-6254-1617 NR 35 TC 21 Z9 22 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 1995 VL 296 IS 1 BP 13 EP 25 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QR541 UT WOS:A1995QR54100007 ER PT J AU BOUCHET, FR COLOMBI, S HIVON, E JUSZKIEWICZ, R AF BOUCHET, FR COLOMBI, S HIVON, E JUSZKIEWICZ, R TI PERTURBATIVE LAGRANGIAN APPROACH TO GRAVITATIONAL-INSTABILITY SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE COSMOLOGY, THEORY; LARGE SCALE STRUCTURE OF UNIVERSE; METHODS, NUMERICAL AND ANALYTICAL ID LARGE-SCALE STRUCTURE; ZELDOVICH APPROXIMATION; NONLINEAR EVOLUTION; ADHESION APPROXIMATION; COSMOLOGICAL CONSTANT; NEWTONIAN COSMOLOGY; FRIEDMANN MODELS; PANCAKE THEORY; UNIVERSE; FLUCTUATIONS AB This paper deals with the time evolution in the matter era of perturbations in Friedman-Lema (i) over cap tre models with arbitrary density parameter Omega, with either a zero cosmological constant, Lambda = 0, or with a non-zero cosmological constant in a spatially flat Universe. Unlike the classical Eulerian approach where the density contrast is expanded in a perturbative series, this analysis relies instead on a perturbative expansion of particles trajectories in Lagrangian coordinates. This brings a number of advantages over the classical analysis. In particular, it enables the description of stronger density contrasts. Indeed the linear term in the Lagrangian perturbative series is the famous Zeldovich approximate solution (1970). The idea to consider the higher order terms was introduced by Moutarde et al. (1991), generalized by Bouchet et al. (1992), and further developed by many others. We present here a systematic and detailed account of this approach. We give analytical results (or fits to numerical results) up to the third order (which is necessary to compute, for instance, the four point spatial correlation function or the corrections to the linear evolution of the two-point correlation function, as well as the secondary temperature anisotropies of the Cosmic Microwave Background). We then proceed to explore the link between the Lagrangian description and statistical measures. We show in particular that Lagrangian perturbation theory provides a natural framework to compute the effect of redshift distortions, using the skewness of the density distribution function as an example. Finally, we show how well the second order theory does as compared to other approximations in the case of spherically symmetric perturbations. We also corn, pare this second order approximation and Zeldovich solution to N-body simulations with scale-free (n = -2) Gaussian initial conditions. We find that second order theory is both simple and powerful. C1 NASA, FERMI NATL ACCELERATOR LAB, CTR ASTROPHYS, BATAVIA, IL 60510 USA. COPERNICUS CTR, PL-00716 WARSAW, POLAND. INST ADV STUDY, PRINCETON, NJ 08540 USA. RP BOUCHET, FR (reprint author), CNRS, INST ASTROPHYS PARIS, 98 BIS BLVD ARAGO, F-75014 PARIS, FRANCE. RI Bouchet, Francois/B-5202-2014 NR 72 TC 204 Z9 204 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 1995 VL 296 IS 3 BP 575 EP 608 PG 34 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QW867 UT WOS:A1995QW86700005 ER PT J AU REID, A SHONE, DL AKUJOR, CE BROWNE, IWA MURPHY, DW PEDELTY, J RUDNICK, L WALSH, D AF REID, A SHONE, DL AKUJOR, CE BROWNE, IWA MURPHY, DW PEDELTY, J RUDNICK, L WALSH, D TI HIGH-RESOLUTION RADIO MAPS OF QUASARS FROM THE JODRELL-BANK 986-MHZ SURVEY SO ASTRONOMY & ASTROPHYSICS SUPPLEMENT SERIES LA English DT Article DE QUASARS, GENERAL; RADIO CONTINUUM, GALAXIES ID VLA OBSERVATIONS; 966-MHZ SURVEY; MERLIN; SPECTROSCOPY; CANDIDATES; SPECTRUM; LOBES; 3C179 AB Radio maps are presented of quasars from the Jodrell Bank 966 MHz survey. The maps are made from observations at 408 MHz with MERLIN, 1464/1666 MHz with the VLA/MERLIN and at 5 GHz with the VLA. The core radio spectra at the three frequencies are shown for nearly all the sources, showing that although a majority of core spectra are hat, some sources have steep-spectrum cores. C1 UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,JODRELL BANK,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND. IMO STATE UNIV,SCH PHYS SCI,OWERRI,NIGERIA. CALTECH,JET PROP LAB,PASADENA,CA 91125. UNIV MINNESOTA,DEPT ASTRON,MINNEAPOLIS,MN 55455. NR 28 TC 44 Z9 45 U1 0 U2 0 PU EDITIONS PHYSIQUE PI LES ULIS CEDEX PA Z I DE COURTABOEUF AVE 7 AV DU HOGGAR, BP 112, 91944 LES ULIS CEDEX, FRANCE SN 0365-0138 J9 ASTRON ASTROPHYS SUP JI Astron. Astrophys. Suppl. Ser. PD APR PY 1995 VL 110 IS 2 BP 213 EP 268 PG 56 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QR542 UT WOS:A1995QR54200001 ER PT J AU TREVES, A FINK, HH MALKAN, M WAGNER, SJ WILKES, BJ BAGANOFF, F HEIDT, J PIAN, E SADUN, A SCHAEIDT, S BONNELL, JT BRINKMANN, W DEMARTINO, D MARASCHI, L TANZI, EG ULRICH, MH WAMSTEKER, W AF TREVES, A FINK, HH MALKAN, M WAGNER, SJ WILKES, BJ BAGANOFF, F HEIDT, J PIAN, E SADUN, A SCHAEIDT, S BONNELL, JT BRINKMANN, W DEMARTINO, D MARASCHI, L TANZI, EG ULRICH, MH WAMSTEKER, W TI MULTIFREQUENCY OBSERVATIONS OF KAZ-102 DURING THE ROSAT ALL-SKY SURVEY SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, ACTIVE; QUASARS, INDIVIDUAL (KAZ 102); ULTRAVIOLET, GALAXIES; X-RAYS, GALAXIES ID SPECTRAL ENERGY-DISTRIBUTIONS; ACTIVE GALACTIC NUCLEI; X-RAY-SPECTRA; STANDARD STARS; ULTRAVIOLET; VARIABILITY; QUASARS; IUE; EXTINCTION; CONTINUA AB The bright quasar Kaz 102, which lies in the vicinity of the North Ecliptic Pole, was monitored during the ROSAT All Sky Survey for 121.5 days from 1990 July 30 to 1991 January 25. In the course of the survey, optical photometry with various filters was performed at several epochs, together with UV (IUE) and optical spectrophotometry. The spectral energy distribution in the 3 x 10(14)-3 x 10(17) Hz range is obtained simultaneously among the various frequencies to less than or similar to 1 day. No clear case of variability can be made in the X-rays, while in the optical and UV variability of 10%-20% is apparent. An analysis of IUE and Einstein archives indicates a doubling timescale of years for the UV and soft X-ray flux. The X-ray photon index, which in 1979 was rather flat (Gamma = 0.8(-0.4)(+0.6)), in 1990/1991 was found to be Gamma = 2.22 +/- 0.13, a typical value for radio-quiet quasars in this energy range. The overall energy distribution and the variability are discussed. C1 MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024. LANDESSTERNWARTE HEIDELBERG KONIGSTUHL,D-69117 HEIDELBERG,GERMANY. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. AGNES SCOTT COLL,DEPT PHYS & ASTRON,DECATUR,GA 30030. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. IUE OBSERV,ESA,E-28080 MADRID,SPAIN. UNIV GENOA,DIPARTIMENTO FIS,I-16133 GENOA,ITALY. CNR,IST FIS COSM,I-20133 MILAN,ITALY. EUROPEAN SO OBSERV,D-85748 GARCHING,GERMANY. RP TREVES, A (reprint author), SCUOLA INT SUPER STUDI AVANZATI,VIA BEIRUT 2-4,I-34014 TRIESTE,ITALY. OI Wilkes, Belinda/0000-0003-1809-2364; Pian, Elena/0000-0001-8646-4858 NR 36 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 APR 1 PY 1995 VL 442 IS 2 BP 589 EP 596 DI 10.1086/175462 PN 1 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QN774 UT WOS:A1995QN77400010 ER PT J AU WEAVER, KA MUSHOTZKY, RF SERLEMITSOS, PJ WILSON, AS ELVIS, M BRIEL, U AF WEAVER, KA MUSHOTZKY, RF SERLEMITSOS, PJ WILSON, AS ELVIS, M BRIEL, U TI THE ORIGIN OF THE SOFT-X-RAY EXCESS IN THE SEYFERT-2 GALAXY NGC-2110 SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXIES, INDIVIDUAL (NGC 2110); GALAXIES, ISM; GALAXIES, NUCLEI; GALAXIES, SEYFERT; RADIATION MECHANISMS, NONTHERMAL; X-RAYS, GALAXIES ID ACTIVE GALAXIES; EMISSION; SPECTRUM; NGC-1068; NEARBY; GAS; HOT AB We present and discuss an X-ray image and a medium-resolution X-ray spectrum of the Seyfert 2 galaxy NGC 2110 obtained with the high-resolution imager (HRI) on ROSAT (0.1-2.4 keV) and Goddard's Broad Band X-Ray Telescope (BBXRT; 0.3-11 keV), respectively. Spatially resolved soft X-ray emission, which peaks 4 '' to the north of the nucleus and near the position of the highest excitation optical emission line gas, is seen in the HRI observation. The extent has a flux of similar to 3 x 10(-13) ergs cm(-2) s(-1) and accounts for 11% +/- 3% of the total 0.1-2.4 keV flux. To model the BBXRT spectrum, a soft excess component is required which has a flux of similar to 3.5 x 10(-13) ergs cm(-2) s(-1) and accounts for similar to 14% +/- 6% of the total 0.1-2.4 keV flux. In addition, BBXRT confirms the presence of an similar to 175 eV equivalent width Fe Ka fluorescence line in NGC 2110. Because of the good agreement between their fluxes, we propose that the soft excess arises from the spatially resolved X-ray emission, This is contrary to previous suggestions that the spectral soft excess in NGC 2110 is due to leakage of the X-ray continuum through a patchy absorber. The temperature of the gas responsible for the soft excess is too high to be accounted for by local shock heating. In order to explain the soft excess and extent as either scattered continuum X-rays or fluorescence from gas photoionized by the nuclear source, the hard X-rays must be emitted anisotropically. However, the soft excess and extent can be well modeled as thermal emission from a hot, outflowing wind, which may also be responsible for confining at least some portion of the optical narrow line-emitting clouds. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. NR 44 TC 42 Z9 42 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1995 VL 442 IS 2 BP 597 EP 609 DI 10.1086/175463 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QN774 UT WOS:A1995QN77400011 ER PT J AU SPIESMAN, WJ HAUSER, MG KELSALL, T LISSE, CM MOSELEY, SH REACH, WT SILVERBERG, RF STEMWEDEL, SW WEILAND, JL AF SPIESMAN, WJ HAUSER, MG KELSALL, T LISSE, CM MOSELEY, SH REACH, WT SILVERBERG, RF STEMWEDEL, SW WEILAND, JL TI NEAR-INFRARED AND FAR-INFRARED OBSERVATIONS OF INTERPLANETARY DUST BANDS FROM THE COBE DIFFUSE INFRARED BACKGROUND EXPERIMENT SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, SOLAR SYSTEM; INTERPLANETARY MEDIUM ID ZODIACAL EMISSION; ORIGIN; IRAS AB Data from the Diffuse Infrared Background Experiment (DIRBE) instrument aboard the COBE spacecraft have been used to examine the near and far infrared signatures of the interplanetary dust (IPD) bands. Images of the dust band pairs at ecliptic latitudes of +/- 1.4 degrees and +/- 10 degrees have been produced at DIRBE wavelengths from 1.25 to 100 mu m. The observations at the shorter wavelengths provide the first evidence of scattered sunlight from particles responsible for the dust bands. It is found that the grains in the bands and those in the smooth IPD cloud have similar spectral energy distributions, suggesting similar compositions and possibly a common origin. The scattering albedos from 1.25 to 3.5 mu m for the grains in the dust bands and those in the smooth IPD cloud are 0.22 and 0.29, respectively. The 10 degrees band pair is cooler (185 +/- 10 K) than the smooth interplanetary dust cloud (259 +/- 10 K). From both parallactic and thermal analyses, the implied location of the grains responsible for the peak brightness of the 10 degrees band pair is 2.1 +/- 0.1 AU from the Sun. A parallactic distance of 1.4 +/- 0.2 AU is found for the peak of the 1.4 degrees band pair. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,APPL RES CORP,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,GEN SCI CORP,GREENBELT,MD 20771. RP SPIESMAN, WJ (reprint author), EUREKA SCI INC,2452 DELMER ST,SUITE 100,OAKLAND,CA 94602, USA. RI Lisse, Carey/B-7772-2016; OI Lisse, Carey/0000-0002-9548-1526; Reach, William/0000-0001-8362-4094 NR 26 TC 18 Z9 18 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD APR 1 PY 1995 VL 442 IS 2 BP 662 EP & DI 10.1086/175470 PN 1 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QN774 UT WOS:A1995QN77400018 ER PT J AU KORISTA, KT ALLOIN, D BARR, P CLAVEL, J COHEN, RD CRENSHAW, DM EVANS, IN HORNE, K KORATKAR, AP KRISS, GA KROLIK, JH MALKAN, MA MORRIS, SL NETZER, H OBRIEN, PT PETERSON, BM REICHERT, GA RODRIGUEZPASCUAL, PM WAMSTEKER, W ANDERSON, KSJ AXON, DJ BENITEZ, E BERLIND, P BERTRAM, R BLACKWELL, JH BOCHKAREV, NG BOISSON, C CARINI, M CARRILLO, R CARONE, TE CHENG, FZ CHRISTENSEN, JA CHUVAEV, KK DIETRICH, M DOKTER, JJ DOROSHENKO, V DULTZINHACYAN, D ENGLAND, MN ESPEY, BR FILIPPENKO, AV GASKELL, CM GOAD, MR HO, LC HUCHRA, JP JIANG, XJ KASPI, S KOLLATSCHNY, W LAOR, A LUMINET, JP MACALPINE, GM MACKENTY, JW MALKOV, YF MAOZ, D MARTIN, PG MATHESON, T MCCOLLUM, B MERKULOVA, N METIK, L MIGNOLI, M MILLER, HR PASTORIZA, MG PELAT, D PENFOLD, J PEREZ, M PEROLA, GC PERSAUD, JL PETERS, J PITTS, R POGGE, RW PRONIK, I PRONIK, VI PTAK, RL RAWLEY, L RECONDOGONZALEZ, MC RODRIGUEZESPINOSA, JM ROMANISHIN, W SADUN, AC SALAMANCA, I SANTOSLLEO, M SEKIGUCHI, K SERGEEV, SG SHAPOVALOVA, AI SHIELDS, JC SHRADER, C SHULL, JM SILBERMANN, NA SITKO, ML SKILLMAN, DR SMITH, HA SMITH, SM SNIJDERS, MAJ SPARKE, LS STIRPE, GM STONER, RE SUN, WH THIELE, U TOKARZ, S TSVETANOV, ZI TURNSHEK, DA VEILLEUX, S WAGNER, RM WAGNER, SJ WANDERS, I WANG, T WELSH, WF WEYMANN, RJ WHITE, RJ WILKES, BJ WILLS, BJ WINGE, C WU, H ZOU, ZL AF KORISTA, KT ALLOIN, D BARR, P CLAVEL, J COHEN, RD CRENSHAW, DM EVANS, IN HORNE, K KORATKAR, AP KRISS, GA KROLIK, JH MALKAN, MA MORRIS, SL NETZER, H OBRIEN, PT PETERSON, BM REICHERT, GA RODRIGUEZPASCUAL, PM WAMSTEKER, W ANDERSON, KSJ AXON, DJ BENITEZ, E BERLIND, P BERTRAM, R BLACKWELL, JH BOCHKAREV, NG BOISSON, C CARINI, M CARRILLO, R CARONE, TE CHENG, FZ CHRISTENSEN, JA CHUVAEV, KK DIETRICH, M DOKTER, JJ DOROSHENKO, V DULTZINHACYAN, D ENGLAND, MN ESPEY, BR FILIPPENKO, AV GASKELL, CM GOAD, MR HO, LC HUCHRA, JP JIANG, XJ KASPI, S KOLLATSCHNY, W LAOR, A LUMINET, JP MACALPINE, GM MACKENTY, JW MALKOV, YF MAOZ, D MARTIN, PG MATHESON, T MCCOLLUM, B MERKULOVA, N METIK, L MIGNOLI, M MILLER, HR PASTORIZA, MG PELAT, D PENFOLD, J PEREZ, M PEROLA, GC PERSAUD, JL PETERS, J PITTS, R POGGE, RW PRONIK, I PRONIK, VI PTAK, RL RAWLEY, L RECONDOGONZALEZ, MC RODRIGUEZESPINOSA, JM ROMANISHIN, W SADUN, AC SALAMANCA, I SANTOSLLEO, M SEKIGUCHI, K SERGEEV, SG SHAPOVALOVA, AI SHIELDS, JC SHRADER, C SHULL, JM SILBERMANN, NA SITKO, ML SKILLMAN, DR SMITH, HA SMITH, SM SNIJDERS, MAJ SPARKE, LS STIRPE, GM STONER, RE SUN, WH THIELE, U TOKARZ, S TSVETANOV, ZI TURNSHEK, DA VEILLEUX, S WAGNER, RM WAGNER, SJ WANDERS, I WANG, T WELSH, WF WEYMANN, RJ WHITE, RJ WILKES, BJ WILLS, BJ WINGE, C WU, H ZOU, ZL TI STEPS TOWARD DETERMINATION OF THE SIZE AND STRUCTURE OF THE BROAD-LINE REGION IN ACTIVE GALACTIC NUCLEI .8. AN INTENSIVE HST, IUE, AND GROUND-BASED STUDY OF NGC-5548 SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE GALAXIES, ACTIVE; GALAXIES, INDIVIDUAL(NGC 5548); GALAXIES, NUCLEI GALAXIES, PHOTOMETRY; GALAXIES, SEYFERT; ULTRAVIOLET, GALAXIES ID SEYFERT-GALAXY NGC-5548; OPTICAL WAVELENGTHS; EMISSION; VARIABILITY; GEOMETRY; QUASARS AB We present the data and initial results from a combined HST/IUE/ground-based spectroscopic monitoring campaign on the Seyfert 1 galaxy NGC 5548 that was undertaken in order to address questions that require both higher temporal resolution and higher signal-to-noise ratios than were obtained in our previous multiwavelength monitoring of this galaxy in 1988-1989. IUE spectra were obtained once every 2 days for a period of 74 days beginning on 1993 March 14. During the last 39 days of this campaign, spectroscopic observations were also made with the HST Faint Object Spectrograph (FOS) on a daily basis. Ground-based observations, consisting of 165 optical spectra and 77 photometric observations(both CCD imaging and aperture photometry), are reported for the period 1992 October-1993 September, although many of the data are concentrated around the time of the satellite-based program. These data constitute a fifth year of intensive optical monitoring of this galaxy. In this contribution we describe the acquisition and reduction of all of the satellite and ground-based data obtained in this program. We describe in detail various photometric problems with the FOS and explain how we identified and corrected for various anomalies. During the HST portion of the monitoring campaign, the 1350 Angstrom continuum flux is found to have varied by nearly a factor of 2. In other wave bands, the continuum shows nearly identical behavior, except that the amplitude of variability is larger at shorter wavelengths, and the continuum light curves appear to show more short-timescale variability at shorter wavelengths. The broad emission lines also vary in flux, with amplitudes that are slightly smaller than the UV continuum variations and with a small time delay relative to the UV continuum. On the basis of simple time-series analysis of the UV and optical continuum and emission-line light curves, we find (1)that the ultraviolet and optical continuum variations are virtually simultaneous, with any lag between the 1350 Angstrom continuum and the 5100 Angstrom continuum amounting to less than about 1 day; (2)that the variations in the highest ionization lines observed, He II lambda 1640 and N V lambda 1240, lag behind the continuum variations by somewhat less than 2 days; and (3) that the velocity held of the C IV-emitting region is not dominated by radial motion. The results on the C Iv velocity held are preliminary and quite uncertain, but there are some weak indications that the emission-line wings(\Delta upsilon\ greater than or equal to 3000 km s(-1)) respond to continuum variations slightly more rapidly than does the core. The optical observations show that the variations in the broad H beta line flux follow the continuum variations with a time lag of around 2 weeks, about twice the lag for Ly alpha and C Iv, as in our previous monitoring campaign on this same galaxy. However, the lags measured for Ly alpha, C Iv, and H beta are each slightly smaller than previous determinations. We confirm two trends reported earlier, namely, (1) that the UV/optical continuum becomes ''harder'' as it gets brighter and (2) that the highest ionization emission lines have the shortest lags, thus indicating radial ionization stratification of a broad-line region that spans over an order of magnitude range in radius. C1 SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. OBSERV PARIS, CNRS, URA 173, F-92195 MEUDON, FRANCE. EUROPEAN SPACE TECHNOL CTR, EUROPEAN SPACE AGCY, DIV ASTROPHYS, ISO OBSERV, 2200 AG NOORDWIJK, NETHERLANDS. UNIV CALIF SAN DIEGO, CTR ASTROPHYS & SPACE SCI, LA JOLLA, CA 92093 USA. NASA, GODDARD SPACE FLIGHT CTR, COMP SCI CORP, ASTRON PROGRAM, GREENBELT, MD 20771 USA. UNIV UTRECHT, STERREKUNDIG INST, 3508 TA UTRECHT, NETHERLANDS. JOHNS HOPKINS UNIV, DEPT PHYS & ASTRON, BALTIMORE, MD 21218 USA. UNIV CALIF LOS ANGELES, DEPT ASTRON, LOS ANGELES, CA 90024 USA. DOMINION ASTROPHYS OBSERV, VICTORIA, BC V8X 4M6, CANADA. TEL AVIV UNIV, SCH PHYS & ASTRON, IL-69978 TEL AVIV, ISRAEL. TEL AVIV UNIV, WISE OBSERV, IL-69978 TEL AVIV, ISRAEL. UNIV OXFORD, DEPT ASTROPHYS, OXFORD OX1 3RH, ENGLAND. OHIO STATE UNIV, DEPT ASTRON, COLUMBUS, OH 43210 USA. NASA, GODDARD SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, GREENBELT, MD 20771 USA. EUROPEAN SPACE AGCY, IUE OBSERV, E-28080 MADRID, SPAIN. NEW MEXICO STATE UNIV, DEPT ASTRON, LAS CRUCES, NM 88003 USA. UNIV MANCHESTER, NUFFIELD RADIO ASTRON LABS, MACCLESFIELD SK11 9DL, CHESHIRE, ENGLAND. EUROPEAN SPACE AGCY, SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. UNIV NACL AUTONOMA MEXICO, INST ASTRON, MEXICO CITY 04510, DF, MEXICO. HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. MOSCOW MV LOMONOSOV STATE UNIV, STERNBERG ASTRON INST, MOSCOW, RUSSIA. UNIV CALIF BERKELEY, SPACE SCI LAB, BERKELEY, CA 94720 USA. LOWELL OBSERV, FLAGSTAFF, AZ 86001 USA. UNIV SCI & TECHNOL CHINA, CTR ASTROPHYS, HEFEI, PEOPLES R CHINA. CRIMEAN ASTROPHYS OBSERV, NAUCHNYI 334413, UKRAINE. UNIV STERNWARTE GOTTINGEN, D-37083 GOTTINGEN, GERMANY. LANDESSTERNWARTE KONIGSTUHL, D-69117 HEIDELBERG, GERMANY. UNIV NEBRASKA, DEPT PHYS & ASTRON, LINCOLN, NE 68588 USA. UNIV CALIF BERKELEY, DEPT ASTRON, BERKELEY, CA 94720 USA. UCL, DEPT PHYS & ASTRON, LONDON WC1E 6BT, ENGLAND. CHINESE ACAD SCI, BEIJING ASTRON OBSERV, BEIJING, PEOPLES R CHINA. CALTECH, DEPT ASTRON, PASADENA, CA 91125 USA. UNIV MICHIGAN, DEPT ASTRON, ANN ARBOR, MI 48109 USA. UNIV TORONTO, CANADIAN INST THEORET ASTROPHYS, TORONTO, ON M5S 1A1, CANADA. OSSERV ASTRON BOLOGNA, I-40126 BOLOGNA, ITALY. GEORGIA STATE UNIV, DEPT PHYS & ASTRON, ATLANTA, GA 30303 USA. UNIV FED RIO GRANDE SUL, INST FIS, DEPT ASTRON, BR-91500 PORTO ALEGRE, RS, BRAZIL. UNIV CALGARY, DEPT PHYS & ASTRON, CALGARY, AB T2N 1N4, CANADA. MT ROYAL COLL, DEPT MATH PHYS & ENGN, CALGARY, AB T3E 6K6, CANADA. UNIV ROME, IST ASTRON, I-00161 ROME, ITALY. UNIV CAMBRIDGE, INST ASTRON, CAMBRIDGE CB3 0HA, ENGLAND. BOWLING GREEN STATE UNIV, DEPT PHYS & ASTRON, BOWLING GREEN, OH 43403 USA. INST ASTROFIS CANARIAS, E-38200 LA LAGUNA, SPAIN. UNIV OKLAHOMA, DEPT PHYS & ASTRON, NORMAN, OK 73019 USA. AGNES SCOTT COLL, BRADLEY OBSERV, DECATUR, GA 30030 USA. AGNES SCOTT COLL, DEPT PHYS & ASTRON, DECATUR, GA 30030 USA. S AFRICAN ASTRON OBSERV, CAPE TOWN 7935, SOUTH AFRICA. RUSSIAN ACAD SCI, SPECIAL ASTROPHYS OBSERV, NIZHNI ARKHYZ 357140, RUSSIA. UNIV ARIZONA, STEWARD OBSERV, TUCSON, AZ 85721 USA. NASA, GODDARD SPACE FLIGHT CTR, GRO SCI SUPPORT CTR, COMP SCI CORP, GREENBELT, MD 20771 USA. UNIV COLORADO, NATL INST STAND & TECHNOL, BOULDER, CO 80309 USA. UNIV COLORADO, JOINT INST LAB ASTROPHYS, BOULDER, CO 80309 USA. MICHIGAN STATE UNIV, DEPT PHYS & ASTRON, E LANSING, MI 48824 USA. UNIV CINCINNATI, DEPT PHYS, CINCINNATI, OH 45221 USA. CTR BASEMENT ASTROPHYS, LAUREL, MD 20723 USA. IRAM, F-38046 ST MARTIN DHERES, FRANCE. UNIV WISCONSIN, DEPT ASTRON, MADISON, WI 53706 USA. NATL CENT UNIV, INST ASTRON, CHUNGLI 32054, TAIWAN. MAX PLANCK INST ASTRON, KONIGSTUHL, D-69117 HEIDELBERG, GERMANY. UNIV PITTSBURGH, DEPT PHYS & ASTRON, PITTSBURGH, PA 15260 USA. KITT PEAK NATL OBSERV, NATL OPT ASTRON OBSERV, TUCSON, AZ 85726 USA. ASTRON OBSERV, S-75120 UPPSALA, SWEDEN. UNIV KEELE, DEPT PHYS, KEELE ST5 5BG, STAFFS, ENGLAND. CARNEGIE INST WASHINGTON OBSERV, PASADENA, CA 91101 USA. UNIV TEXAS, MCDONALD OBSERV, AUSTIN, TX 78712 USA. UNIV TEXAS, DEPT ASTRON, AUSTIN, TX 78712 USA. RI Morris, Simon/G-7981-2011; 王, 挺贵/B-8293-2013; Skillman, David/C-8995-2013; Recondo, Carmen/B-1215-2012; Stirpe, Giovanna/O-9393-2015; Mignoli, Marco/O-9426-2015; OI Morris, Simon/0000-0003-4866-110X; Recondo, Carmen/0000-0001-9813-6798; Stirpe, Giovanna/0000-0002-3702-8731; Mignoli, Marco/0000-0002-9087-2835; Espey, Brian/0000-0002-2457-1380; Gaskell, C/0000-0003-4888-2009; SUN, WEI-HSIN/0000-0002-7474-8658 NR 47 TC 229 Z9 229 U1 1 U2 8 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0067-0049 J9 ASTROPHYS J SUPPL S JI Astrophys. J. Suppl. Ser. PD APR PY 1995 VL 97 IS 2 BP 285 EP 330 DI 10.1086/192144 PG 46 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QN780 UT WOS:A1995QN78000004 ER PT J AU SCHNEIDER, JP NORBURY, JW CUCINOTTA, FA AF SCHNEIDER, JP NORBURY, JW CUCINOTTA, FA TI PARAMETERIZATION OF SPECTRAL DISTRIBUTIONS FOR PION AND KAON PRODUCTION IN PROTON-PROTON COLLISIONS SO ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES LA English DT Article DE ACCELERATION OF PARTICLES; COSMIC RAYS; NUCLEAR REACTIONS, NUCLEOSYNTHESIS, ABUNDANCES AB Accurate semi-empirical parameterizations of the energy-differential cross sections for charged pion and kaon production from proton-proton collisions are presented at energies relevant to cosmic rays. The parameterizations depend on the outgoing meson momentum and also the proton energy, and are able to be reduced to very simple analytical formulas suitable for cosmic-ray transport. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP SCHNEIDER, JP (reprint author), UNIV WISCONSIN,DEPT PHYS,LA CROSSE,WI 54601, USA. NR 14 TC 0 Z9 0 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 APR PY 1995 VL 97 IS 2 BP 571 EP 574 DI 10.1086/192151 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QN780 UT WOS:A1995QN78000011 PM 11539269 ER PT J AU LEBLANC, A SCHNEIDER, V SPECTOR, E EVANS, H ROWE, R LANE, H DEMERS, L LIPTON, A AF LEBLANC, A SCHNEIDER, V SPECTOR, E EVANS, H ROWE, R LANE, H DEMERS, L LIPTON, A TI CALCIUM-ABSORPTION, ENDOGENOUS EXCRETION, AND ENDOCRINE CHANGES DURING AND AFTER LONG-TERM BED REST SO BONE LA English DT Article DE BED REST; CA BALANCE; CA ABSORPTION; ENDOGENOUS FECAL EXCRETION ID BONE-MINERAL LOSS; DISUSE OSTEOPOROSIS; IMMOBILIZATION; HYPERCALCEMIA; HOMEOSTASIS AB Negative calcium balance is a known consequence of bed rest, and is manifested in elevated urine and fecal calcium (Ca), Elevated fecal Ca can result from either decreased absorption, increased endogenous fecal excretion, or both, We measured the Ca absorption and endogenous fecal excretion in eight healthy male volunteers before and during 4 months of bed rest. Dual isotope (n = 6) or single isotope (n = 2) methods in conjunction with Ca balance were used to calculate true and net Ca absorption and endogenous fecal excretion, Stool Ca increased from 797 mg/day (mean intake 991 mg/day) to 911 mg/day during bed rest, whereas urine Ca excretion increased from 174 to 241 mg/day, True Ca absorption decreased from 31 +/- 7% of Ca intake pre-bed rest to 24 +/- 2% during bed rest, (p < 0.05) and returned toward pre-bed rest values within 5-6 weeks following reambulation, Endogenous fecal excretion did not change significantly, and therefore, most of the increased fecal Ca resulted from changes in absorption, However, in one individual, endogenous fecal Ca excretion was the major contributor to Ca loss, Ionized Ca and pyridinium crosslinks increased and 1,25(OH)(2) vitamin D decreased during bed rest, similar to the decrease in Ca absorption; parathyroid hormone (PTH), calcitonin, serum albumin, phosphorus, and total serum Ca were unchanged. Although alkaline phosphatase, osteocalcin, and PTH. were unchanged during bed rest, they were elevated during reambulation, These changes accompanied by increased Ca absorption and balance and decreased ionized and total serum Ca suggest a rebound in bone formation following immobilization. C1 BAYLOR COLL MED,DEPT MED,HOUSTON,TX 77030. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX. HOSP UNIV PENN,MILTON S HERSHEY MED CTR,HERSHEY,PA. FU NCRR NIH HHS [RR00350, RR02558] NR 23 TC 66 Z9 68 U1 0 U2 2 PU ELSEVIER SCIENCE PUBL CO INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 8756-3282 J9 BONE JI Bone PD APR PY 1995 VL 16 IS 4 SU S BP S301 EP S304 DI 10.1016/S8756-3282(95)80193-6 PG 4 WC Endocrinology & Metabolism SC Endocrinology & Metabolism GA RC576 UT WOS:A1995RC57600009 PM 7626318 ER PT J AU OTTERMAN, J SUSSKIND, J BRAKKE, T KIMES, D PIELKE, R LEE, TJ AF OTTERMAN, J SUSSKIND, J BRAKKE, T KIMES, D PIELKE, R LEE, TJ TI INFERRING THE THERMAL-INFRARED HEMISPHERIC EMISSION FROM A SPARSELY-VEGETATED SURFACE BY DIRECTIONAL MEASUREMENTS SO BOUNDARY-LAYER METEOROLOGY LA English DT Article ID ENERGY-BALANCE; WHEAT CANOPY; TEMPERATURES; PROTRUSIONS; ABSORPTION; PLANE AB The thermal-infrared (longwave) emission from a vegetated terrain is generally anisotropic, i.e., the emission temperature varies with the view direction. If a directional measurement of temperature is considered to be equal to the effective temperature of the hemispheric emission, then the estimate of the latter can be significantly in error. The view-direction (zenith angle theta(eq)) at which the emission equivalence does hold is determined in our modeling study. In a two-temperature field-of-view (soil and plants), theta(eq) falls in a narrow range depending on plant density and canopy architecture. theta(eq) does not depend on soil and (uniform) plant temperatures nor on their ratio, even though the pattern of emission vs, the view direction depends crucially on this ratio. For a sparse canopy represented as thin, vertical cylindrical stalks (or vertical blades uniformly distributed in azimuth) with horizontal facets, theta(eq) ranges from 48 to 53 circle depending on the optical density of the vertical elements alone. When plant elements are modeled as small spheres, theta(eq) lies between 53 to 57 degrees (for the same values of the canopy optical density). Only for horizontal leaves (a truly planophile canopy) is the temperature measured from any direction equal to the temperature of the hemispheric emission. When the emission temperature changes with optical depth within the canopy at a specified rate, theta(eq) depends to some extent on that rate. For practically any sparsely vegetated surface, a directional measurement at the zenith angle of 50 degrees offers an appropriate evaluation of the hemispheric emission, since the error in the estimate will, at most, only slightly exceed 1% (around 4 W m(-2). Estimates of the hemispheric emission through a nadir measurement, on the other hand, can be in error in some cases by about 10%, i.e., on the order of 40 W m(-2). C1 LAND ATMOSPHERE OCEAN RES,GREENBELT,MD 20770. NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,GREENBELT,MD 20771. COLORADO STATE UNIV,DEPT ATMOSPHER SCI,FT COLLINS,CO 80523. RP OTTERMAN, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CODE 9104,GREENBELT,MD 20771, USA. RI Pielke, Roger/A-5015-2009 NR 23 TC 20 Z9 21 U1 0 U2 1 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0006-8314 J9 BOUND-LAY METEOROL JI Bound.-Layer Meteor. PD APR PY 1995 VL 74 IS 1-2 BP 163 EP 180 DI 10.1007/BF00715715 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QZ292 UT WOS:A1995QZ29200008 ER PT J AU SCHAEFER, K AF SCHAEFER, K TI NASA EARTH OBSERVATION SYSTEM DATA INFORMATION-SYSTEM SO BULLETIN OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE LA English DT Article RP SCHAEFER, K (reprint author), NASA,WASHINGTON,DC 20546, USA. NR 0 TC 1 Z9 1 U1 0 U2 1 PU AMER SOC INFORM SCI MEMBER #110113 PI SILVER SPRING PA 8720 GEORGIA AVE SUITE 501, SILVER SPRING, MD 20910 SN 0095-4403 J9 B AM SOC INFORM INF JI Bull. Amer. Soc. Inf. Sci. PD APR-MAY PY 1995 VL 21 IS 4 BP 13 EP 15 PG 3 WC Information Science & Library Science SC Information Science & Library Science GA RZ964 UT WOS:A1995RZ96400003 ER PT J AU MARTIN, M BERNATH, A TAKACS, M AF MARTIN, M BERNATH, A TAKACS, M TI THE IGARSS CD PROCEEDINGS CHALLENGE SO CD-ROM PROFESSIONAL LA English DT Article RP MARTIN, M (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PEMBERTON PRESS INC PI WILTON PA 462 DANBURY RD, WILTON, CT 06897-2126 SN 1049-0833 J9 CD-ROM PROF JI CD-ROM Prof. PD APR PY 1995 VL 8 IS 4 BP 100 EP & PG 0 WC Information Science & Library Science SC Information Science & Library Science GA QP534 UT WOS:A1995QP53400022 ER PT J AU STEWART, KT HAYES, BC EASTMAN, CI AF STEWART, KT HAYES, BC EASTMAN, CI TI LIGHT TREATMENT FOR NASA SHIFTWORKERS SO CHRONOBIOLOGY INTERNATIONAL LA English DT Article DE CIRCADIAN RHYTHM; SHIFTWORK; LIGHT; SPACE SHUTTLE; SLEEP ID SEASONAL AFFECTIVE-DISORDER; CIRCADIAN-RHYTHMS; BRIGHT LIGHT; SLEEP; THERAPY; SHIFT AB Intense artificial light can phase-shift circadian rhythms and improve performance, sleep, land well-being during shiftwork simulations. In real shiftworkers, however, exposure to sunlight and other time cues may decrease the efficacy of light treatment, and occupational and family responsibilities may make it impractical. With these considerations in mind, we designed and tested light-treatment protocols for NASA personnel who worked on shifted schedules during two Space Shuttle missions. During the prelaunch week, treatment, subjects self-administered light of similar to 10,000 lux at times of day that phase-delay circadian rhythms. Treatment continued during the missions and for several days;afterward. No treatment was administered to subjects in the control group. Treatment subjects reported better sleep, performance, and physical and emotional well-being than control subjects and rated the treatment as highly effective for promoting adjustment to their work schedules. Light treatment is both feasible and beneficial for NASA personnel who must work on shifted schedules during Space Shuttle missions. C1 RUSH PRESBYTERIAN ST LUKES MED CTR,DEPT PSYCHOL & SOCIAL SCI,BIOL RHYTHMS RES LAB,CHICAGO,IL 60612. GEORGE C MARSHALL SPACE FLIGHT CTR,MISS OPERAT LAB,DIV MISS ENGN,MAN SYST INTEGRAT BRANCH,HUNTSVILLE,AL. OI Eastman, Charmane/0000-0002-4057-1233 NR 19 TC 47 Z9 48 U1 0 U2 8 PU MARCEL DEKKER INC PI NEW YORK PA 270 MADISON AVE, NEW YORK, NY 10016 SN 0742-0528 J9 CHRONOBIOL INT JI Chronobiol. Int. PD APR PY 1995 VL 12 IS 2 BP 141 EP 151 DI 10.3109/07420529509064509 PG 11 WC Biology; Physiology SC Life Sciences & Biomedicine - Other Topics; Physiology GA QZ584 UT WOS:A1995QZ58400007 PM 8653800 ER PT J AU CHOU, JJ AF CHOU, JJ TI HIGHER-ORDER BEZIER CIRCLES SO COMPUTER-AIDED DESIGN LA English DT Article DE RATIONAL BEZIER CURVES; CIRCLES; CIRCULAR ARCS AB In the paper, it is proved that the order of the Bezier curves forming a full circle must be at least 6 for the curves to have all positive weights. Cubic Bezier curves that are circular arcs are also studied, and the control points for all such curves are derived. Some geometric properties of these curves are discussed. RP CHOU, JJ (reprint author), NASA,AMES RES CTR,COMP SCI CORP,M-S T27B-2,MOFFETT FIELD,CA 94035, USA. NR 6 TC 18 Z9 18 U1 0 U2 2 PU BUTTERWORTH-HEINEMANN LTD PI OXFORD PA LINACRE HOUSE JORDAN HILL, OXFORD, OXON, ENGLAND OX2 8DP SN 0010-4485 J9 COMPUT AIDED DESIGN JI Comput.-Aided Eng. PD APR PY 1995 VL 27 IS 4 BP 303 EP 309 DI 10.1016/0010-4485(95)91140-G PG 7 WC Computer Science, Software Engineering SC Computer Science GA QX215 UT WOS:A1995QX21500007 ER PT J AU MATHEWS, GJ TOWHEED, SS AF MATHEWS, GJ TOWHEED, SS TI NSSDC OMNIWEB - THE FIRST SPACE PHYSICS WWW-BASED DATA BROWSING AND RETRIEVAL-SYSTEM SO COMPUTER NETWORKS AND ISDN SYSTEMS LA English DT Article; Proceedings Paper CT 3rd International World-Wide Web Conference CY APR 10-14, 1995 CL DARMSTADT, GERMANY DE DATA ANALYSIS; DATA RETRIEVAL; SCIENTIFIC DATA SERVER; CLIENT SERVER; USER INTERFACE DESIGN; CDF; IDL AB The National Space Science Data Center (NSSDC), located at NASA's Goddard Space Flight Center, provides access to a wide variety of data from NASA spaceflight missions. Traditionally, the NSSDC has made data available in a variety of hard media and via on-line systems. However, the WWW provides an exciting new enhancement by allowing users to examine and browse the data before retrieval. This paper presents OMNIWeb, a WWW-based system that allows users to produce plots and retrieve data. The browsing and retrieving capability was designed to aid researchers in identifying trends and to obtain the data through an uninterrupted process. C1 HUGHES STX CORP,GREENBELT,MD 20771. RP MATHEWS, GJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,NATL SCI DATA CTR,INTEROPERABLE OFF,CODE 6332,GREENBELT,MD 20771, USA. NR 8 TC 5 Z9 5 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-7552 J9 COMPUT NETWORKS ISDN JI Comput. Netw. ISDN Syst. PD APR PY 1995 VL 27 IS 6 BP 801 EP 808 DI 10.1016/0169-7552(95)00033-4 PG 8 WC Computer Science, Information Systems; Engineering, Electrical & Electronic; Telecommunications SC Computer Science; Engineering; Telecommunications GA QV575 UT WOS:A1995QV57500009 ER PT J AU DEFAINCHTEIN, R ZALESAK, ST LOHNER, R SPICER, DS AF DEFAINCHTEIN, R ZALESAK, ST LOHNER, R SPICER, DS TI FINITE-ELEMENT SIMULATION OF A TURBULENT MHD SYSTEM - COMPARISON TO A PSEUDOSPECTRAL SIMULATION SO COMPUTER PHYSICS COMMUNICATIONS LA English DT Article ID DIMENSIONAL MAGNETOHYDRODYNAMIC TURBULENCE; TANG VORTEX SYSTEM; COMPRESSIBLE MEDIUM; FLOW; EQUATIONS; EVOLUTION AB A finite element MHD algorithm is used to simulate a two-dimensional, viscous and resistive turbulent model, namely the Orszag-Tang vortex. The results are compared to a pseudo-spectral simulation of the same system reported by Dahlburg and Picone (Phys. Fluids B 1 (1989) 2153). The agreement of results from both methods supports the contention that the finite element method can appropriately simulate systems exhibiting turbulence, thus enabling the use of realistic geometries and boundary conditions, as well as adaptive refinement on simulations of turbulent systems. A short discussion on the behavior of del . B is presented. An inverse correlation between spatial resolution and the magnitude of del . B was found. The relevance of our findings to Adaptive Mesh Refinement is briefly discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,CTR COMPUTAT SCI,GREENBELT,MD 20771. GEORGE MASON UNIV,INST COMPUTAT SCI & INFORMAT,FAIRFAX,VA 22030. RP DEFAINCHTEIN, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771, USA. NR 33 TC 4 Z9 4 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 1995 VL 86 IS 1-2 BP 25 EP 39 DI 10.1016/0010-4655(94)00143-P PG 15 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA QQ909 UT WOS:A1995QQ90900003 ER PT J AU JOVIC, S DRIVER, D AF JOVIC, S DRIVER, D TI REYNOLDS-NUMBER EFFECT ON THE SKIN FRICTION IN SEPARATED FLOWS BEHIND A BACKWARD-FACING STEP SO EXPERIMENTS IN FLUIDS LA English DT Note ID TURBULENT SHEAR-LAYER C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. ELORET INST,PALO ALTO,CA 94303. NR 9 TC 50 Z9 51 U1 0 U2 16 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0723-4864 J9 EXP FLUIDS JI Exp. Fluids PD APR PY 1995 VL 18 IS 6 BP 464 EP 467 DI 10.1007/BF00208471 PG 4 WC Engineering, Mechanical; Mechanics SC Engineering; Mechanics GA QX994 UT WOS:A1995QX99400010 ER PT J AU CARLSON, HR AF CARLSON, HR TI CONSISTENT YEARLY APPEARANCE OF AGE-0 WALLEYE POLLOCK, THERAGRA-CHALCOGRAMMA, AT A COASTAL SITE IN SOUTHEASTERN ALASKA, 1973-1994 SO FISHERY BULLETIN LA English DT Note ID WESTERN GULF; LARVAL; ABUNDANCE; JUVENILE RP CARLSON, HR (reprint author), NOAA,NATL MARINE FISHERIES SERV,ALASKA FISHERIES SCI CTR,AUKE BAY LAB,11305 GLACIER HIGHWAY,JUNEAU,AK 99801, USA. NR 16 TC 6 Z9 6 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 1995 VL 93 IS 2 BP 386 EP 390 PG 5 WC Fisheries SC Fisheries GA QR392 UT WOS:A1995QR39200015 ER PT J AU JONES, JH WALKER, D PICKETT, DA MURRELL, MT BEATTIE, P AF JONES, JH WALKER, D PICKETT, DA MURRELL, MT BEATTIE, P TI EXPERIMENTAL INVESTIGATIONS OF THE PARTITIONING OF NB, MO, BA, CE, PB, RA, TH, PA, AND U BETWEEN IMMISCIBLE CARBONATE AND SILICATE LIQUIDS SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID OLDOINYO-LENGAI; SERIES DISEQUILIBRIA; ISOTOPIC SYSTEMATICS; MASS-SPECTROMETRY; MANTLE; MAGMA; CONSTRAINTS; TANZANIA; CLINOPYROXENE; METASOMATISM AB Liquid carbonate/liquid silicate partition coefficients (D) for a suite of incompatible elements (Nb, Mo, Ba, Ce, Pb, Th, U) have been determined experimentally. For one experiment, D's for Pa and Pa were also determined. The partitioning behavior is shown to be a regular function of the ionic field strength (z/r) of the partitioned elements. At constant temperature, increasing pressure from 7 to 20 kbar caused little change in the measured D. At constant pressure, increasing temperature causes all D's to approach unity, as the temperature nears the critical temperature and the two liquids become compositionally similar. Addition of P or F to the system enlarges the stability field of carbonate but does not affect the partitioning behavior of our suite of elements. However, both P and F are strongly partitioned into the carbonate liquid. Omphacite/carbonate Liquid D's at 50-60 kbar have also been determined. Our results for D-U and D-Th are similar to those found previously for augite/silicate liquid. Thorium is more compatible than U in pyroxene, indicating that excesses of Th-230/U-238 found in MORE cannot be explained by fractionation between pyroxene and melt. The Soret effect in carbonate liquids is quite small, in contrast to the effect in silicate liquids. In general, we see no evidence for Soret separation in our experiments, implying that endmember Ca-, Na-, and Mg-carbonate liquids have simple speciations and mix nearly ideally. This observation suggests that the results of our liquid/liquid partitioning studies do not strongly depend on the exact composition of the carbonate. Our experimentally determined liquid-liquid partition coefficients can explain recent fractionations of Pb-210/U-238 and Ra-226/U-238 in carbonatitic lavas from the Oldoinyo Lengai volcano, but cannot explain similar fractionations in Th-230/U-238. Pb-210 has the shortest half-life of these nuclides, and is, therefore, the most sensitive to the exact timing and mechanism of fractionation. Because we can explain Pb-210/U-238 in terms of recent, instantaneous liquid immiscibility, we favor this model for the origin of the deviations of Pb-210/U-238 and Ra-226/U-238 from those expected under secular equilibrium. If our interpretation is correct, some other fractionation process(es) must have fractionated Th (and perhaps Pa) from U, Pa, and Pb in the Oldoinyo Lengai carbonatites. C1 COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964. LOS ALAMOS NATL LAB,LOS ALAMOS,NM 87545. UNIV CAMBRIDGE,DEPT EARTH SCI,CAMBRIDGE CB2 3EQ,ENGLAND. RP JONES, JH (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 42 TC 72 Z9 81 U1 0 U2 10 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD APR PY 1995 VL 59 IS 7 BP 1307 EP 1320 DI 10.1016/0016-7037(95)00045-2 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QT166 UT WOS:A1995QT16600009 ER PT J AU BOGARD, DD GARRISON, DH NORMAN, M SCOTT, ERD KEIL, K AF BOGARD, DD GARRISON, DH NORMAN, M SCOTT, ERD KEIL, K TI AR-39-AR-40 AGE AND PETROLOGY OF CHICO - LARGE-SCALE IMPACT MELTING ON THE L-CHONDRITE PARENT BODY SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID AR-40-AR-39 AGES; REHEATED CHONDRITES; THERMAL HISTORIES; RB-SR; ROCKS; METAMORPHISM; TEMPERATURE; STANDARDS; BRECCIAS; DELLEN AB Our studies of the 105 kg Chico L chondrite show that it contains similar to 60% impact melt and the largest volume of impact melt recognized in stony meteorites. We suggest that it is part of a much larger dike complex that formed when chondritic impact melt was intruded into host chondrite during a large, if not catastrophic, impact on the L chondrite parent body at about 0.5 Ga. Petrologic and Ar-39-Ar-40 dating studies were made on several lithologies, including the massive melt zone, host chondrite, and melt-chondrite boundaries, for the purpose of studying the melting and thermal histories associated with impacts on small bodies and their effects on the K-Ar chronometer. The chondritic host is shocked to stage S6 and contains pockets and veins of melt. There are no unmelted clasts in the interior of the melt; coalesced metal-troilite nodules reach up to 2 cm in size. Melt near the contact with the host chondrite contains numerous clasts and quenched more rapidly. Metal-troilite textures suggest cooling rates of similar to 0.1 degrees C/s in the interior of the melt dike during crystallization. Secondary kamacite rims indicate cooling at 0.01-1 degrees C/y over the range of 700-500 degrees C, consistent with an impact-heated volume of up to a kilometer in thickness. Compositions of olivines and pyroxenes are generally similar in melt and chondritic host, reflecting rapid crystallization, not metamorphic equilibration. The interior melt shows an overall depletion in K, whereas the melt near the boundary is enriched in K. The Ar-39-Ar-40 release spectra during stepwise heating of both melt and chondrite samples can be divided into two parts, based on Ar diffusion properties and K/Ca ratios. The low-temperature, high K/Ca phase of both melt and host chondrite show ages of 0.54-0.78 Ga. Ages of the high-temperature, low K/Ca phase of the melt are comparable or higher, 0.61-1.35 Ga, whereas those of the host chondrite are even higher, 0.87-1.86 Ga, due to lesser degrees of degassing. Isochron plots for several melt samples suggest an age of similar to 0.53 Ga and the presence of variable amounts of excess Ar-40 not completely degassed by the impact. Even this age, however, is significantly higher than the previously reported Rb-Sr isochron age of 0.467 +/- .015 Ga. The apparent retention of radiogenic Ar-40 in the Chico impact melt, in spite of its relatively large size, absence of clasts, and moderately slow cooling rate below 700 degrees C, raises questions as to the reliability of using melts for Ar-39-Ar-40 dating of meteoritic impact events. C1 NASA,LYNDON B JOHNSON SPACE CTR,LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. UNIV HAWAII MANOA,SCH OCEAN & EARTH SCI & TECHNOL,HAWAII INST GEOPHYS & PLANETOL,HONOLULU,HI 96822. UNIV HAWAII,HAWAII CTR VOLCANOL,HONOLULU,HI 96822. RP BOGARD, DD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,CODE SN4,HOUSTON,TX 77058, USA. NR 58 TC 88 Z9 89 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD APR PY 1995 VL 59 IS 7 BP 1383 EP 1399 DI 10.1016/0016-7037(95)00051-Z PG 17 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QT166 UT WOS:A1995QT16600015 ER PT J AU LERNER, NR AF LERNER, NR TI INFLUENCE OF MURCHISON OR ALLENDE MINERALS ON HYDROGEN-DEUTERIUM EXCHANGE OF AMINO-ACIDS SO GEOCHIMICA ET COSMOCHIMICA ACTA LA English DT Article ID CARBONACEOUS CHONDRITES; METEORITE; NITROGEN AB Deuterium-enriched amino acids occur in the Murchison carbonaceous chrondrite. This meteorite underwent a period of aqueous alteration with isotopically light water. With the objective of setting limits on the conditions of aqueous alteration, the exchange of the carbon-bonded hydrogen atoms of amino acids with D2O has been studied from 295 to 380 K as a function of time and meteorite/heavy water ratio. The amount of Murchison or Allende dust present has a significant effect on the rate and amount of hydrogen-deuterium exchange observed. At elevated temperatures, the alpha-hydrogens of all the amino acids studied were found to exchange with deuterium. In glycine and aspartic acid, this process resulted in total exchange of the carbon-bonded hydrogen. A completely deuterated isotopomer of alanine was produced in significant quantities only when the rock/water ratio was greater than 0.5. No exchange of carbon-bonded hydrogens was observed in the case of amino acids which do not possess an alpha-hydrogen atom. The rates of H/D exchange for amino acids observed here did not correspond to deuterium enrichment of the amino acids in the Murchison meteorite. These results suggest that H/D exchange with water had a negligible effect on the observed deuterium enrichment of amino acids found in Murchison temperature at which the amino acids were exposed to liquid water was close to 273 K. RP LERNER, NR (reprint author), NASA,AMES RES CTR,PLANETARY BIOL BRANCH,MOFFETT FIELD,CA 94035, USA. NR 17 TC 6 Z9 6 U1 0 U2 3 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0016-7037 J9 GEOCHIM COSMOCHIM AC JI Geochim. Cosmochim. Acta PD APR PY 1995 VL 59 IS 8 BP 1623 EP 1631 DI 10.1016/0016-7037(95)00068-B PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QW166 UT WOS:A1995QW16600015 PM 11540046 ER PT J AU GLECKLER, PJ RANDALL, DA BOER, G COLMAN, R DIX, M GALIN, V HELFAND, M KIEHL, J KITOH, A LAU, W LIANG, XY LYKOSSOV, V MCAVANEY, B MIYAKODA, K PLANTON, S STERN, W AF GLECKLER, PJ RANDALL, DA BOER, G COLMAN, R DIX, M GALIN, V HELFAND, M KIEHL, J KITOH, A LAU, W LIANG, XY LYKOSSOV, V MCAVANEY, B MIYAKODA, K PLANTON, S STERN, W TI CLOUD-RADIATIVE EFFECTS ON IMPLIED OCEANIC ENERGY TRANSPORTS AS SIMULATED BY ATMOSPHERIC GENERAL-CIRCULATION MODELS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID HEAT-TRANSPORT; BUDGETS; CLIMATE AB This paper summarizes the ocean surface net energy flux simulated by fifteen atmospheric general circulation models constrained by realistically-varying sea surface temperatures and sea ice as part of the Atmospheric Model Intercomparison Project. In general, the simulated energy fluxes are within the very large observational uncertainties. However, the annual mean oceanic meridional heat transport that would be required to balance the simulated surface fluxes is shown to be critically sensitive to the radiative effects of clouds, to the extent that even the sign of the Southern Hemisphere ocean heat transport can be affected by the errors in simulated cloud-radiation interactions. It is suggested that improved treatment of cloud radiative effects should help in the development of coupled atmosphere-ocean general circulation models. C1 CANADIAN CLIMATE CTR,VICTORIA,BC,CANADA. BUR METEOROL RES CTR,MELBOURNE,AUSTRALIA. DEPT NUMER MATH,MOSCOW,RUSSIA. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. METEOROL RES INST,TSUKUBA,JAPAN. SUNY ALBANY,ALBANY,NY 12222. DYNAM EXTENTED RANGE FORCASTING,GEOPHYS FLUID DYNAM LAB,PRINCETON,NJ. CTR NATL RECH METEOROL,TOULOUSE,FRANCE. COLORADO STATE UNIV,DEPT ATMOSPHER SCI,FT COLLINS,CO 80523. RP GLECKLER, PJ (reprint author), LAWRENCE LIVERMORE NATL LAB,PROGRAM CLIMATE DIAGNOSIS & INTERCOMPARISON,LIVERMORE,CA 94551, USA. RI Gleckler, Peter/H-4762-2012; Dix, Martin/A-2334-2012; Randall, David/E-6113-2011; PLANTON, Serge/L-3112-2016 OI Gleckler, Peter/0000-0003-2816-6224; Dix, Martin/0000-0002-7534-0654; Randall, David/0000-0001-6935-4112; NR 16 TC 59 Z9 59 U1 1 U2 5 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 1 PY 1995 VL 22 IS 7 BP 791 EP 794 DI 10.1029/95GL00113 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QR153 UT WOS:A1995QR15300013 ER PT J AU TRATT, DM MENZIES, RT AF TRATT, DM MENZIES, RT TI EVOLUTION OF THE PINATUBO VOLCANIC AEROSOL COLUMN ABOVE PASADENA, CALIFORNIA OBSERVED WITH A MIDINFRARED BACKSCATTER LIDAR SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID STRATOSPHERIC AEROSOL; VERTICAL PROFILES; SIZE DISTRIBUTION; VOLATILITY AB The evolution of the volcanic debris plume originating from the June 1991 eruption of Mt. Pinatubo has been monitored since its genesis using a ground-based backscatter lidar facility sited at the Jet Propulsion Laboratory (JPL). Both absolute and relative pre- and post-Pinatubo backscatter observations are in accord with Mie scattering projections based on measured aerosol particle size distributions reported in the literature. The post-Pinatubo column-integrated backscatter coefficient peaked approximately 400 days after the eruption, and the observed upper boundary of the aerosol column subsided at a rate of approximately 200 m mon-1. RP TRATT, DM (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Tratt, David/A-7884-2009 OI Tratt, David/0000-0002-3942-6848 NR 20 TC 5 Z9 5 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 1 PY 1995 VL 22 IS 7 BP 807 EP 810 DI 10.1029/95GL00112 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QR153 UT WOS:A1995QR15300017 ER PT J AU WATERS, JW MANNEY, GL READ, WG FROIDEVAUX, L FLOWER, DA JARNOT, RF AF WATERS, JW MANNEY, GL READ, WG FROIDEVAUX, L FLOWER, DA JARNOT, RF TI UARS MLS OBSERVATIONS OF LOWER STRATOSPHERIC CIO IN THE 1992-93 AND 1993-94 ARCTIC WINTER VORTICES SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; MICROWAVE LIMB SOUNDER; POLAR VORTEX; OZONE; CHLORINE AB UARS MLS measurements of lower stratospheric ClO during the 1992-93 and 1993-94 Arctic winters are presented. Enhanced ClO in the 1992-93 winter was first observed in early December, and extensively during February when temperatures were continually low enough for PSCs. Sporadic episodes of enhanced ClO were observed for most of the 1993-94 winter as minimum temperatures hovered near the PSC threshold, with largest ClO amounts occurring in early March after a sudden deep cooling in late February. C1 JET PROP LAB,MAIL STOP 183-701,PASADENA,CA 91109. NR 16 TC 34 Z9 34 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 1 PY 1995 VL 22 IS 7 BP 823 EP 826 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QR153 UT WOS:A1995QR15300021 ER PT J AU NESBITT, FL MONKS, PS PAYNE, WA STIEF, LJ TOUMI, R AF NESBITT, FL MONKS, PS PAYNE, WA STIEF, LJ TOUMI, R TI THE REACTION O(3P)+HOBR - TEMPERATURE-DEPENDENCE OF THE RATE-CONSTANT AND IMPORTANCE OF THE REACTION AS AN HOBR STRATOSPHERIC LOSS PROCESS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID BRO AB The absolute rate constant for the reaction O(P-3) + HOBr has been measured between T=233K and 423K using the discharge-flow kinetic technique coupled to mass spectrometric detection. The value of the rate coefficient at room temperature is (2.5+/-0.6) x 10(-11) cm3 molecule-1 s-1 and the derived Arrhenius expression is (1.4+/-0.5) x 10(-10) exp[(-430 +/- 260)/T] cm3 molecule-1 s-1. From these rate data the atmospheric lifetime of HOBr with respect to reaction with O(P-3) is about 0.6h at z = 25 km which is comparable to the photolysis lifetime based on recent measurements of the UV cross section for HOBr. Implications for HOBr loss in the stratosphere have been tested using a 1D photochemical box model. With the inclusion of the rate parameters and products for the O + HOBr reaction, calculated concentration profiles of BrO increase by up to 33% around z = 35 km. This result indicates that the inclusion of the O + HOBr reaction in global atmospheric chemistry models may have an an impact on bromine partitioning in the middle atmosphere. C1 COPPIN STATE COLL,DEPT NAT SCI,BALTIMORE,MD 21216. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,DEPT PHYS,LONDON SW7 2BZ,ENGLAND. RP NESBITT, FL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Monks, Paul/H-6468-2016 OI Monks, Paul/0000-0001-9984-4390 NR 14 TC 8 Z9 8 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 1 PY 1995 VL 22 IS 7 BP 827 EP 830 DI 10.1029/95GL00375 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QR153 UT WOS:A1995QR15300022 ER PT J AU AVALLONE, LM TOOHEY, DW SCHAUFFLER, SM POLLOCK, WH HEIDT, LE ATLAS, EL CHAN, KR AF AVALLONE, LM TOOHEY, DW SCHAUFFLER, SM POLLOCK, WH HEIDT, LE ATLAS, EL CHAN, KR TI IN-SITU MEASUREMENTS OF BRO DURING AASE-II SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ARCTIC STRATOSPHERIC EXPEDITION; ANTARCTIC OZONE; DEPLETION; PINATUBO; CHLORINE; VORTEX; WINTER; CLO AB BrO measured from the NASA ER-2 during AASE II exhibited a mean value (for 20-minute averages) of 5.4 +/- 0.3 pptv, with a standard deviation of 3.1 pptv. Ratios of BrO to available inorganic bromine (Br(y)) show only slight increases in polar regions relative to midlatitudes. A comparison between observed latitudinal and diurnal variations of this same ratio and that calculated by photochemical models shows reasonable agreement in behavior, but significant discrepancies in magnitude. It is unclear whether this difference is due to errors in measurements, models or both. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NATL CTR ATMOSPHER RES,BOULDER,CO 80307. RP AVALLONE, LM (reprint author), UNIV CALIF IRVINE,EARTH SYST SCI,IRVINE,CA 92717, USA. RI Toohey, Darin/A-4267-2008; Atlas, Elliot/J-8171-2015 OI Toohey, Darin/0000-0003-2853-1068; NR 20 TC 28 Z9 28 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 1 PY 1995 VL 22 IS 7 BP 831 EP 834 DI 10.1029/95GL00393 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QR153 UT WOS:A1995QR15300023 ER PT J AU SEN, B TOON, GC BLAVIER, JF SZETO, JT FLEMING, EL JACKMAN, CH AF SEN, B TOON, GC BLAVIER, JF SZETO, JT FLEMING, EL JACKMAN, CH TI BALLOON-BORNE OBSERVATIONS OF MIDLATITUDE HYDROFLUORIC-ACID SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID 2-DIMENSIONAL MODEL; STRATOSPHERE AB Measurements of stratospheric HF have been made by the JPL MkIV interferometer during high-altitude balloon flights. Infrared solar absorption spectra were acquired near 35-degrees- N at altitudes between local tropopause and 38 km. Volume mixing ratio profiles of HF derived from 4 flights (1990-93), in conjunction with simultaneously observed N2O profiles, indicate an average rate of HF increase of (5.5+/-0.3)% per year, in agreement with time-dependent, two-dimensional model simulations (6% per year) and ATMOS measurements. C1 APPL RES CORP,LANDOVER,MD 20785. NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771. RP SEN, B (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Jackman, Charles/D-4699-2012 NR 16 TC 5 Z9 5 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 1 PY 1995 VL 22 IS 7 BP 835 EP 838 DI 10.1029/95GL00006 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QR153 UT WOS:A1995QR15300024 ER PT J AU CHANDRA, S JACKMAN, CH FLEMING, EL AF CHANDRA, S JACKMAN, CH FLEMING, EL TI RECENT TRENDS IN OZONE IN THE UPPER-STRATOSPHERE - IMPLICATIONS FOR CHLORINE CHEMISTRY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SATELLITE AB We have studied the implications of recent trends in the annual mean and the amplitude of the annual harmonic of ozone in the upper stratosphere from the 15 years of the combined data from the Nimbus-7 SBUV and the NOAA-11 SBUV/2 instruments. This was done in the context of the GSFC 2D model predictions of these trends which are based on plausible scenarios of anthropogenic Cly increase in the atmosphere. The comparison of the observed and model-estimated annual mean ozone trends show some similarity in their latitude and altitude characteristics. Both the model and data show a maximum ozone decrease of -6 to -10% per decade at high latitudes in the upper stratosphere. However, there are also significant differences between the observed and computed trends which may be related to both the model uncertainty and the uncertainty for the long term instrument drift. The observations also suggest a decrease of 10-25% per decade in the annual amplitude of ozone at 2 mb between 40-degrees-60-degrees in both hemispheres, with a relatively larger interannual variability in the northern hemisphere. These values are in general agreement with the model predictions and thus provide additional support in favor of the chlorine induced changes in ozone in the upper stratosphere. C1 APPL RES CORP,LANDOVER,MD 20785. RP CHANDRA, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 916,GREENBELT,MD 20771, USA. RI Jackman, Charles/D-4699-2012 NR 13 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 1 PY 1995 VL 22 IS 7 BP 843 EP 846 DI 10.1029/94GL03395 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QR153 UT WOS:A1995QR15300026 ER PT J AU WILSON, JW REGINATTO, M HAJNAL, F CHUN, SY AF WILSON, JW REGINATTO, M HAJNAL, F CHUN, SY TI CALCULATION OF DOSE, DOSE-EQUIVALENT, AND RELATIVE BIOLOGICAL EFFECTIVENESS FOR HIGH CHARGE AND ENERGY ION-BEAMS SO HEALTH PHYSICS LA English DT Article DE DOSE EQUIVALENT; RELATIVE BIOLOGICAL EFFECTIVENESS; DOSE; TISSUE, BODY ID 670A MEV NE-20; FRAGMENTATION; DEPTH; WATER AB The Green's function for the transport of ions of high charge and energy is utilized with a nuclear fragmentation database to evaluate dose, dose equivalent, and RBE for C3H10T1/2 cell survival and neoplastic transformation as a function of depth in soft tissue. Such evaluations are useful to estimates of biological risk for high altitude aircraft, space operations, accelerator operations, and biomedical applications. C1 US DOE, ENVIRONM MEASUREMENTS LAB, NEW YORK, NY 10014 USA. OLD DOMINION UNIV, NORFOLK, VA 23508 USA. RP WILSON, JW (reprint author), NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NR 21 TC 7 Z9 7 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 1995 VL 68 IS 4 BP 532 EP 538 DI 10.1097/00004032-199504000-00010 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 QM612 UT WOS:A1995QM61200011 PM 7883565 ER PT J AU YORIO, NC MACKOWIAK, CL WHEELER, RM SAGER, JC AF YORIO, NC MACKOWIAK, CL WHEELER, RM SAGER, JC TI VEGETATIVE GROWTH OF POTATO UNDER HIGH-PRESSURE SODIUM, HIGH-PRESSURE SODIUM SON-AGRO, AND METAL HALIDE LAMPS SO HORTSCIENCE LA English DT Article DE SOLANUM TUBEROSUM; BLUE LIGHT; STEM ELONGATION; INTERNODE LENGTH; SPECTRAL QUALITY; PHOTOMORPHOGENESIS ID LIGHT; PLANTS; LETTUCE AB Potato (Solanum tuberosum L. cvs. Norland and Denali) plants were grown under high-pressure sodium (HPS), metal halide (MH), and blue-light-enhanced SON-Agro high-pressure sodium (HPS-S) lamps to study the effects of lamp spectral quality on vegetative growth, All plants were initiated from in vitro nodal cultures and grown hydroponically for 35 days at 300 mu mol . m(-2) . s(-1) photosynthetic photon flux (PPF) with a 12-hourlight/12-hour dark photoperiod and matching 20C/16C thermoperiod. 'Denali' main stems and internodes were significantly longer under HPS compared to MH, while under HPS-S, lengths were intermediate relative to those under other lamp types, but not significantly different,'Norland' plants showed no significant differences in stem and internode length among lamp types. Total dry weight of 'Denali' plants was unaffected by lamp type, but 'Norland' plants grown with HPS had significantly higher dry weight than those under either MPS-S or MH. Spectroradiometer measurements from the various lamps verified the manufacturer's claims of a 30% increase in ultraviolet-blue (350 to 450 mm) output from the HPS-S relative to standard HPS lamps. However, the data from 'Denali' suggest that at 300 mu mol . m(2) . s(-1) total PPF, the increased blue from HPS-S lamps is still insufficient to consistently maintain short stem growth typical of blue-rich irradiance environments. C1 NASA,BIOMED OPERAT & RES OFF,KENNEDY SPACE CTR,FL 32899. RP YORIO, NC (reprint author), DYNAM CORP,MAIL CODE DYN-3,KENNEDY SPACE CTR,FL 32899, USA. NR 14 TC 13 Z9 14 U1 0 U2 0 PU AMER SOC HORTICULTURAL SCIENCE PI ALEXANDRIA PA 701 NORTH SAINT ASAPH STREET, ALEXANDRIA, VA 22314-1998 SN 0018-5345 J9 HORTSCIENCE JI Hortscience PD APR PY 1995 VL 30 IS 2 BP 374 EP 376 PG 3 WC Horticulture SC Agriculture GA RL233 UT WOS:A1995RL23300057 ER PT J AU ROOSSEROTE, M DROSSART, P ENCRENAZ, T LELLOUCH, E CARLSON, RW BAINES, KH TAYLOR, FW CALCUTT, SB AF ROOSSEROTE, M DROSSART, P ENCRENAZ, T LELLOUCH, E CARLSON, RW BAINES, KH TAYLOR, FW CALCUTT, SB TI THE THERMAL STRUCTURE AND DYNAMICS OF THE ATMOSPHERE OF VENUS BETWEEN 70 AND 90 KM FROM THE GALILEO-NIMS SPECTRA SO ICARUS LA English DT Article ID MESOSPHERE AB An analysis of thermal profiles and dynamics over a wide range of latitudes for the venusian atmosphere between 70 and 90 km is presented based on high spatial resolution infrared spectra of the night side obtained by the near infrared mapping spectrometer (NIMS) experiment during the Galileo-Venus encounter in February 1990. Using the 4.3-mu m CO2 absorption band, the temperature profile is retrieved in the 75- to 91-km altitude region over a latitudinal range of -59 degrees to +64 degrees. Compared to earlier observations from the Pioneer Venus mission, the temperature at 91 km is about 10 K higher and between 74 and 83 km about 3.6 K colder. An equator to pole warming at constant pressure levels is found and implications for the zonal wind profiles are drawn under the assumption that the atmosphere is in cyclostrophic balance in the region of 70 to 90 km. The results are in correspondence with direct wind measurements from ground-based observations at 95 km and 105 km altitude. (C) 1995 Academic Press, Inc. C1 JET PROPULS LAB,PASADENA,CA 91109. UNIV OXFORD,DEPT ATMOSPHER PHYS,CLARENDON LAB,OXFORD OX1 3PU,ENGLAND. RP ROOSSEROTE, M (reprint author), OBSERV PARIS,DESPA,F-92195 MEUDON,FRANCE. OI Calcutt, Simon/0000-0002-0102-3170 NR 27 TC 29 Z9 29 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 1995 VL 114 IS 2 BP 300 EP 309 DI 10.1006/icar.1995.1063 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU162 UT WOS:A1995QU16200007 ER PT J AU HINSON, DP JENKINS, JM AF HINSON, DP JENKINS, JM TI MAGELLAN RADIO OCCULTATION MEASUREMENTS OF ATMOSPHERIC WAVES ON VENUS SO ICARUS LA English DT Article ID MIDDLE ATMOSPHERE; GRAVITY-WAVES; CLOUD PATTERNS; THERMAL TIDES; ZONAL WINDS; TURBULENCE; MAINTENANCE; CONVECTION; MESOSPHERE; IMAGES AB Radio occultation experiments were conducted at Venus on three consecutive orbits of the Magellan spacecraft in October 1991. Each occultation occurred over the same topography (67 degrees N, 127 degrees E) and at the same local time (22(h)5(m)), but the data are sensitive to zonal variations because the atmosphere rotates significantly during one orbit. Through comparisons between observations and predictions of standard wave theory, we have demonstrated that small-scale oscillations in retrieved temperature profiles as well as scintillations in received signal intensity are caused by a spectrum of vertically propagating internal gravity waves. There is a strong similarity between the intensity scintillations observed here and previous measurements, which pertain to a wide range of locations and experiment dates. This implies that the same basic phenomenon underlies all the observations and hence that gravity waves are a persistent, global feature of Venus' atmosphere. We obtained a fairly complete characterization of a gravity wave that appears above the middle cloud in temperature measurements on all three orbits. The amplitude and vertical wavelength are about 4 K and 2.5 km, respectively, at 65 km. A model for radiative damping implies that the wave intrinsic frequency is similar to 2 x 10(-4) rad sec(-1); the corresponding ratio between horizontal and vertical wavelengths is similar to 100. The wave is nearly stationary relative to the surface or the Sun. Radiative attenuation limits the wave amplitude at altitudes above similar to 65 km, leading to wave drag on the mean zonal winds of about +0.4 m sec(-1) per day (eastward). The sign, magnitude, and location of this forcing suggest a possible role in explaining the decrease with height in the zonal wind speed that is believed to occur above the cloud tops. Temperature oscillations with larger vertical wavelengths (5-10 km) were also observed on all three orbits, but we are unable to interpret these unambiguously. (C) 1995 Academic Press, Inc. C1 NASA,AMES RES CTR,SETI INST,MOFFETT FIELD,CA 94035. RP HINSON, DP (reprint author), STANFORD UNIV,CTR RADAR ASTRON,STANFORD,CA 94305, USA. NR 49 TC 62 Z9 64 U1 1 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 1995 VL 114 IS 2 BP 310 EP 327 DI 10.1006/icar.1995.1064 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU162 UT WOS:A1995QU16200008 ER PT J AU BAINES, KH MICKELSON, ME LARSON, LE FERGUSON, DW AF BAINES, KH MICKELSON, ME LARSON, LE FERGUSON, DW TI THE ABUNDANCES OF METHANE AND ORTHO/PARA HYDROGEN ON URANUS AND NEPTUNE - IMPLICATIONS OF NEW LABORATORY 4-0 H-2 QUADRUPOLE LINE PARAMETERS SO ICARUS LA English DT Article ID GIANT PLANETS; JOVIAN PLANETS; ATMOSPHERE; CH4; VOYAGER-2; BANDS; SPECTROPHOTOMETRY; TROPOSPHERE; SPECTRUM; JUPITER AB The tropospheric methane molar fraction (f(CH4,t)) and the ortho/para hydrogen ratio are derived for Uranus and Neptune based on new determinations of spectroscopic parameters for key hydrogen features as reported by D. W. Ferguson et al. (1993, J. Mol. Spec. 160, 315-325). For each planet, the relatively weak laboratory linestrengths (approximately 30 and 15% less than the theoretical 4-0 S(0) and S(1) linestrengths, respectively) results, when compared to analyses adopting theoretical values, in a similar to 30% decrease in the tropospheric methane ratio and a comparable increase in the pressure level of the optically thick cloudtop marking the bottom of the visible atmosphere (P-cld). The increase in the ratio of S(1)/S(0) linestrengths from 4.4 (theoretical) to similar to 5.9 (measured) results in a decrease in the range of viable ortho/para ratios; an equilibrium hydrogen distribution is now the best fit for both planets. For Uranus, we find f(CH4,t) = 0.016(-0.005)(+0.007), P-cld = 3.1(-0.2)(+1.1) bars, and 0.85 < f(eH2) 1.00 (where f(eH2) and 1 - f(eH2) denote the fraction of H-2 in the equilibrium and normal state, respectively) compared to the K. H. Baines and J. T. Bergstralh (1986, Icarus 56, 543-559) values of f(CH4,t) = 0.030(-0.010)(+0.016), P-cld = 2.7(-0.4)(+0.5) bars, and 0.63 < f(eH2) < 0.95. For Neptune, we find f(CH4,t) = 0.022(-0.006)(+0.005), P-cld 3.8(-0.3)(+0.7) bars, and 0.89 < f(eH2) less than or equal to 1.0 compared to the K. H. Baines and W. H. Smith (1990, Icarus 85, 65-108) values of f(CH4,t) = 0.03 +/- 0.007, P-cld = 3.3(-0.1)(+0.5) bars, and 0.85 < f(eH2) less than or equal to 1.0. The methane mixing ratios reported here are in agreement with the value of 0.023 derived by the Voyager Radio Occulatation Experiment (G. F. Lindal 1992, Astron. J. 103, 967-982) for Neptune, but slightly lower than the Voyager Uranus measurement of 0.023 reported by G. F. Lindal et al. (1987, J. Geophys. Res. 99, 14987-15001). The relative carbon-to-hydrogen abundances of 20(-6)(+9) and 28(-8)(+7) times the solar value of 4.7 x 10(-4) derived by D. L. Lambert (1978, Mon. Not. R. Astron. Soc. 192, 249-272) for Uranus and Neptune support planetary formation mechanisms involving the dissolution of carbon-bearing planetesimals in the atmospheres of both planets during their early stages of formation (e.g., J. B. Pollack et al., 1986, Icarus 67, 409-443). (C) 1995 Academic Press, Inc. C1 DENISON UNIV,GRANVILLE,OH 43023. OHIO STATE UNIV,COLUMBUS,OH 43210. RP BAINES, KH (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 49 TC 80 Z9 80 U1 0 U2 5 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 1995 VL 114 IS 2 BP 328 EP 340 DI 10.1006/icar.1995.1065 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU162 UT WOS:A1995QU16200009 ER PT J AU DAVIS, PA TANAKA, KL GOLOMBEK, MP AF DAVIS, PA TANAKA, KL GOLOMBEK, MP TI TOPOGRAPHY OF CLOSED DEPRESSIONS, SCARPS, AND GRABENS IN THE NORTH THARSIS REGION OF MARS - IMPLICATIONS FOR SHALLOW CRUSTAL DISCONTINUITIES AND GRABEN FORMATION SO ICARUS LA English DT Article ID GROUND ICE; DIKE EMPLACEMENT; MARTIAN CRUST; RICH PLANET; ALBA-PATERA; RIFT ZONES; STABILITY; HISTORY; TERRAIN; ICELAND AB Using Viking Orbiter images, detailed photoclinometric profiles were obtained across 10 irregular depressions, 32 fretted fractures, 49 troughs and pits, 124 solitary scarps, and 370 simple grabens in the north Tharsis region of Mars. These data allow inferences to be made on the shallow crustal structure of this region. The frequency modes of measured scarp heights correspond with previous general thickness estimates of the heavily cratered and ridged plains units. The depths of the flat-floored irregular depressions (55-175 m), fretted fractures (85-890 m), and troughs and pits (60-1620 m) are also similar to scarp heights (thicknesses) of the geologic units in which these depressions occur, which suggests that the depths of these flat-floored features were controlled by erosional base levels created by lithologic contacts. Although the features have a similar age, both their depths and their observed local structural control increase in the order listed above, which suggests that the more advanced stages of associated fracturing facilitated the development of these depressions by increasing permeability. If a ground-ice zone is a factor in development of these features, as has been suggested, our observation that the depths of these features decrease with increasing latitude suggests that either the thickness of the ground-ice zone does not increase poleward or the depths of the depressions were controlled by the top of the ground-ice zone whose depth may decrease with latitude. Deeper discontinuities are inferred from fault-intersection depths of 370 simple grabens (assuming 60 degrees dipping faults that initiate at a mechanical discontinuity) in Tempe Terra and Alba Patera and from the depths of the large, flat-floored troughs in Tempe Terra. The frequency distributions of these fault-intersection and large trough depths show a concentration at 1.0-1.6 km depth, similar to data obtained for Syria, Sinai, and Lunae Plana. The consistency of these depth data over such a large region of western Mars suggests that a discontinuity or a process that transcends local and regional geology is responsible for the formation of these features. If this discontinuity is represented by the base of the cryosphere, its uniform depth over 55 degrees of latitude suggests that the cryosphere did not thicken poleward. Alternatively, the concentration of depths at 1.0-1.6 km may represent the upper level of noneruptive dike ascent (lateral dike propagation) of Mars, which is controlled by gravity and atmospheric pressure and magma and country-rock characteristics, and was probably controlled, in part, by ground ice. Fault-intersection depths in the north Tharsis region locally extend down to a depth of 5-7 km. The depth data between 2 and 3 km are attributed to the discontinuity at the interface of megaregolith and basement or to the upper limit of noneruptive dike ascent of magma with a high volatile content. Intersection depths greater than 3 km, which were found at Alba Patera, may be due to the megaregolith-basement discontinuity, which was buried and depressed by volcanic loading, or to the upper level of noneruptive dike ascent of magma with a low volatile content. The near absence of narrow simple grabens with fault-initiation depths less than 0.6-1.0 km in this study area, as well as in most of western Mars, suggests that this depth represents the minimum depth that normal faults can initiate; at shallower depths tension cracks or joints would form instead. This hypothesis is supported by the application of the Griffith failure criterion to this minimum depth of normal fault initiation, which suggests that shallow crustal materials have a tensile strength of 2-4 MPa throughout most of western Mars, in close agreement with previous estimates of tensile strength of martian basaltic rock. (C) 1995 Academic Press, Inc. C1 JET PROPULS LAB,PASADENA,CA 91109. RP DAVIS, PA (reprint author), US GEOL SURVEY,2255 N GEMINI DR,FLAGSTAFF,AZ 86001, USA. NR 75 TC 28 Z9 28 U1 1 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD APR PY 1995 VL 114 IS 2 BP 403 EP 422 DI 10.1006/icar.1995.1071 PG 20 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU162 UT WOS:A1995QU16200015 ER PT J AU KIELY, PA DOCTER, DP VANG, TA TAYLOR, GW EVALDSSON, PA CLAISSE, PR TELL, B BROWNGOEBELER, KF AF KIELY, PA DOCTER, DP VANG, TA TAYLOR, GW EVALDSSON, PA CLAISSE, PR TELL, B BROWNGOEBELER, KF TI AC CHARACTERIZATION OF THE P-INVERTED BURIED-CHANNEL HETEROSTRUCTURE FET AND ITS SUITABILITY FOR COMPLEMENTARY ELECTRONICS SO IEE PROCEEDINGS-CIRCUITS DEVICES AND SYSTEMS LA English DT Article DE FIELD-EFFECT TRANSISTORS; ELECTRONIC DEVICES ID TRANSISTOR AB The high-frequency characteristics of the inverted p-channel BCHFET are presented. A unity current gain frequency of 1.4 GHz for a 1.3 mu m device is obtained. DC operation of a complementary inverter is shown using the n inversion channel NFET and the inverted p-channel BCHFET. C1 AT&T BELL LABS,HOLMDEL,NJ 07733. AT&T BELL LABS,MURRAY HILL,NJ 07974. HUGHES RES LABS,MALIBU,CA 90265. CALTECH,JET PROP LAB,PASADENA,CA 91109. UNIV CONNECTICUT,STORRS,CT 06269. RP KIELY, PA (reprint author), MOTOROLA INC,TEMPE,AZ, USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTS PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTS, ENGLAND SG1 2AY SN 1350-2409 J9 IEE P-CIRC DEV SYST JI IEE Proc.-Circuit Device Syst. PD APR PY 1995 VL 142 IS 2 BP 105 EP 108 DI 10.1049/ip-cds:19951810 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA QV909 UT WOS:A1995QV90900002 ER PT J AU WINSLOW, C AF WINSLOW, C TI HUBBLE-SPACE-TELESCOPE SOLAR-ARRAY CHANGE-OUT, MISSION ANOMALIES AND RETURNED FLIGHT HARDWARE SO IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE LA English DT Article AB During the successful First Servicing Mission on the Hubble Space Telescope the two solar arrays were replaced with new and improved solar arrays. An electrical short and four solar array mechanical system anomalies occurred: 1) the upper outer bistem on the +V2 wing had developed kinks and then failed to retract; 2) additional friction between the solar array latch fitting and the aft latch berthing microswitch guard probably caused the failure of the primary deployment mechanism to deploy the solar array wings; 3) the secondary deployment mechanism retract limit microswitch activation is believed to be a result of the dynamic motion of the wings during the retraction event. Successful retraction took place after five attempts; and 4) additional torques induced during extra vehicular activity, flight support system and orbiter activities caused the wings to move from the latching destination. The physical appearance and durability of the materials on the solar array and the physical position of hardware indicators were investigated at Kennedy Space Center after the flight servicing mission. Evidence of micrometeoroid damage and the darkened silicone coatings were apparent. Isolation and continuity tests confirmed the location of shorts which occurred during the First Servicing Mission. RP WINSLOW, C (reprint author), LOCKHEED TECH OPERAT CO INC,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20770, USA. NR 0 TC 0 Z9 0 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 0885-8985 J9 IEEE AERO EL SYS MAG JI IEEE Aerosp. Electron. Syst. Mag. PD APR PY 1995 VL 10 IS 4 BP 3 EP 13 DI 10.1109/62.382250 PG 11 WC Engineering, Aerospace; Engineering, Electrical & Electronic SC Engineering GA QU291 UT WOS:A1995QU29100003 ER PT J AU WIN, MZ CHEN, CC SCHOLTZ, RA AF WIN, MZ CHEN, CC SCHOLTZ, RA TI OPTICAL PHASE-LOCKED LOOP (OPLL) FOR AN AMPLITUDE-MODULATED COMMUNICATIONS LINK USING SOLID-STATE LASERS SO IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS LA English DT Article ID YAG RING LASER; LINEWIDTH REQUIREMENTS; PERFORMANCE ANALYSIS; LOCAL OSCILLATOR; RECEIVER; SYSTEMS; LOCKING; NOISE AB Theoretical analysis is formulated for a solid state laser based optical phase-locked loop (OPLL) disturbed by shot noise, amplitude modulated noise, and frequency noise. The frequency noise spectral density of solid state lasers is modeled to contain a white component, a 1/f component, and a strong 1/f(2) component at the laser output. This model is verified and spectral content of each component is measured using an open-loop RF frequency discriminator, The choice of loop filter is made by considering the frequency noise components, transient effects, and the loop damping factor zeta. The total phase error variance as a function of loop bandwidth is displayed for several values of carrier signal-to-noise ratio for the measured frequency noise spectrum. Optimal loop bandwidth is also calculated as a function of carrier signal-to-noise ratio. An OPLL experiment is performed, and measured phase error variance is compared with the theoretical predictions using the measured frequency noise spectrum. The results show that the measured phase error variance closely matches the theoretical predictions. C1 UNIV SO CALIF,INST COMMUN SCI,DEPT EE SYST,LOS ANGELES,CA 90089. RP WIN, MZ (reprint author), CALTECH,JET PROP LAB,OPT COMMUN GRP,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 23 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 0733-8716 J9 IEEE J SEL AREA COMM JI IEEE J. Sel. Areas Commun. PD APR PY 1995 VL 13 IS 3 BP 569 EP 576 DI 10.1109/49.372415 PG 8 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA QP821 UT WOS:A1995QP82100009 ER PT J AU EPP, LW HOPPE, DJ CHINN, GC AF EPP, LW HOPPE, DJ CHINN, GC TI SCATTERING FROM FERRITE BODIES OF REVOLUTION USING A HYBRID APPROACH SO IEEE MICROWAVE AND GUIDED WAVE LETTERS LA English DT Article AB The scattered fields from axisymmetric problems containing anisotropic media are found by a Hybrid Finite Element method. In particular a symmetric formulation for bodies of revolution that incorporates a Finite Element formulation for axially magnetized ferrite materials is presented. The method is applied to a ferrite cylinder with quartz matching layers, A Gaussian beam input is used to predict the Faraday rotation through the ferrite cylinder and display it visually. RP EPP, LW (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 0 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 1051-8207 J9 IEEE MICROW GUIDED W JI IEEE Microw. Guided Wave Lett. PD APR PY 1995 VL 5 IS 4 BP 111 EP 113 DI 10.1109/75.372808 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA QN925 UT WOS:A1995QN92500003 ER PT J AU YOUNG, JL AF YOUNG, JL TI PROPAGATION IN LINEAR DISPERSIVE MEDIA - FINITE-DIFFERENCE TIME-DOMAIN METHODOLOGIES SO IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION LA English DT Note ID FORMULATION; SCATTERING; EQUATIONS; PLASMA; FDTD AB Finite difference time-domain (FDTD) methodologies are presented for electromagnetic wave propagation in two different kinds of linear dispersive media: an Nth order Lorentz and an Mth order Debye medium. The temporal discretization is accomplished by invoking the central difference approximation for the temporal derivatives that appear in the first-order differential equations. From this, the final equations are temporally advanced using the classical leapfrog method. One-dimensional scattering from a dielectric slab is chosen for a test case. Provided that the maximum operating frequency times the time step is small and that the wave is adequately resolved in space, as shown in the error analysis, the agreement between the computed and exact solutions will be excellent. The attached data, which are associated with the four pole Lorentz dielectric and the five pole Debye medium, verify this assertion. RP YOUNG, JL (reprint author), UNIV IDAHO,NASA,SPACE ENGN RES CTR,DEPT ELECT ENGN,MOSCOW,ID 83844, USA. RI Young, Jeffrey/B-1591-2017 OI Young, Jeffrey/0000-0001-6647-4303 NR 20 TC 89 Z9 100 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 0018-926X J9 IEEE T ANTENN PROPAG JI IEEE Trans. Antennas Propag. PD APR PY 1995 VL 43 IS 4 BP 422 EP 426 DI 10.1109/8.376042 PG 5 WC Engineering, Electrical & Electronic; Telecommunications SC Engineering; Telecommunications GA QR629 UT WOS:A1995QR62900013 ER PT J AU SCHEID, RE BAYARD, DS AF SCHEID, RE BAYARD, DS TI A GLOBALLY OPTIMAL MINIMAX SOLUTION FOR SPECTRAL OVERBOUNDING AND FACTORIZATION SO IEEE TRANSACTIONS ON AUTOMATIC CONTROL LA English DT Note ID H-INFINITY; IDENTIFICATION AB In this paper, an algorithm is introduced to find a minimum phase transfer function of specified order whose magnitude ''tightly'' overbounds a specified real-valued nonparametric function of frequency. This method has direct application to transforming nonparametric uncertainty bounds (available from system identification experiments and/or plant modeling) into parametric representations required for modern robust control design software (i.e., a minimum-phase transfer function multiplied by a norm-bounded perturbation). RP SCHEID, RE (reprint author), JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 21 TC 12 Z9 12 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9286 J9 IEEE T AUTOMAT CONTR JI IEEE Trans. Autom. Control PD APR PY 1995 VL 40 IS 4 BP 712 EP 716 DI 10.1109/9.376103 PG 5 WC Automation & Control Systems; Engineering, Electrical & Electronic SC Automation & Control Systems; Engineering GA QR130 UT WOS:A1995QR13000013 ER PT J AU BLUNDELL, R TONG, CYE PAPA, DC LEOMBRUNO, RL ZHANG, XL PAINE, S STERN, JA LEDUC, HG BUMBLE, B AF BLUNDELL, R TONG, CYE PAPA, DC LEOMBRUNO, RL ZHANG, XL PAINE, S STERN, JA LEDUC, HG BUMBLE, B TI A WIDE-BAND FIXED-TUNED SIS RECEIVER FOR 200-GHZ OPERATION SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article; Proceedings Paper CT 5th International Symposium on Space Terahertz Technology CY MAY, 1994 CL UNIV MICHIGAN, ANN ARBOR, MI HO UNIV MICHIGAN ID RADIO ASTRONOMY AB We report on the design and development of a heterodyne receiver, designed to cover the frequency range 176-256 GHz. This receiver incorporates a niobium superconductor-insulator-superconductor (SIS) tunnel junction mixer, which, chiefly for reasons of reliability and ease of operation, is a fixed-tuned waveguide design, On-chip tuning is provided to resonate out the junction's geometric capacitance and produce a good match to the waveguide circuit, Laboratory measurements on the first test receiver indicate that the required input bandwidth (about 40%) is achieved with an average receiver noise temperature of below 50 K, Mixer conversion gain is observed at some frequencies, and the lowest measured receiver noise is less than 30 K, Furthermore, the SIS mixer used in this receiver is of simple construction, is easy to assemble and is therefore a good candidate for duplication. C1 CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. RP BLUNDELL, R (reprint author), HARVARD SMITHSONIAN CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. OI Tong, Edward/0000-0002-7736-4203 NR 10 TC 46 Z9 46 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD APR PY 1995 VL 43 IS 4 BP 933 EP 937 DI 10.1109/22.375257 PN 2 PG 5 WC Engineering, Electrical & Electronic SC Engineering GA QT617 UT WOS:A1995QT61700004 ER PT J AU CHOUDHURY, D SIEGEL, PH SMITH, RP RAISANEN, AV MARTIN, SC FRERKING, MA AF CHOUDHURY, D SIEGEL, PH SMITH, RP RAISANEN, AV MARTIN, SC FRERKING, MA TI INTEGRATED BACK-TO-BACK BARRIER-N-N+ VARACTOR DIODE TRIPLER USING A SPLIT-WAVE-GUIDE BLOCK SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article; Proceedings Paper CT 5th International Symposium on Space Terahertz Technology CY MAY, 1994 CL UNIV MICHIGAN, ANN ARBOR, MI HO UNIV MICHIGAN AB The back-to-back barrier-N-N+ (bbBNN) varactor is a nonlinear device being developed for frequency multiplier applications above 100 GHz. Its symmetrical C-V characteristic, low series resistance, freedom from external bias and suitability to planarization make it an ideal choice for high frequency, low power, odd harmonic generation. In this paper, the performance of a 220-GHz waveguide tripler using, for the first time, a planar GaAs bbBNN device integrated on a quartz microstrip circuit is presented, A new split-waveguide block design has been employed to provide the proper embedding impedances to the device at the input and third harmonic output frequencies, A flange-to-flange tripling efficiency of 7% has been obtained at 220 GHz with an output power in excess of 700 mu W. This is believed to be the highest conversion efficiency yet reported for a tripler with an integrated device at this frequency, Theoretical calculations indicate that substantial improvement is possible with modest changes to the device and circuit parameters. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. HELSINKI UNIV TECHNOL,RADIO LAB,SF-02150 ESPOO,FINLAND. RI Raisanen, Antti/G-2405-2013 NR 16 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 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD APR PY 1995 VL 43 IS 4 BP 948 EP 954 DI 10.1109/22.375259 PN 2 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA QT617 UT WOS:A1995QT61700006 ER PT J AU SCHOELKOPF, RJ ZMUIDZINAS, J PHILLIPS, TG LEDUC, HG STERN, JA AF SCHOELKOPF, RJ ZMUIDZINAS, J PHILLIPS, TG LEDUC, HG STERN, JA TI MEASUREMENTS OF NOISE IN JOSEPHSON-EFFECT MIXERS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article; Proceedings Paper CT 5th International Symposium on Space Terahertz Technology CY MAY, 1994 CL UNIV MICHIGAN, ANN ARBOR, MI HO UNIV MICHIGAN ID TEMPERATURE AB We present new heterodyne receiver results obtained at 100 GHz using resistively-shunted Nb and NbN tunnel junctions, In addition, we have carried out accurate measurements of the available noise power of these devices at the L-band (1.5 GHz) IF frequency. Both the heterodyne and the output noise measurements show that the noise of these devices can be a factor of five or more higher than that predicted by the simple current-biased RSJ model, The noise approaches the appropriate thermal or thermal and shot noise limits for bias voltages where the nonlinearity is not strong (i.e., V > I(C)R(N)), but as expected from the RSJ model, can be significantly higher at the low voltages where the mixers are typically biased. The bias voltage dependence of the noise shows structure which is associated with resonances in the RF embedding circuit, Surprisingly, we find that changes in the high-frequency (100 GHz) impedance presented to the junction can dramatically affect the magnitude and voltage dependence of the low-frequency (1.5 GHz) noise, This emphasizes the necessity of very closely matching the junction to free space over a wide frequency range. C1 CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. RP SCHOELKOPF, RJ (reprint author), CALTECH,DOWNS LAB PHYS,PASADENA,CA 91125, USA. RI Schoelkopf, Robert/J-8178-2012 NR 13 TC 6 Z9 6 U1 0 U2 9 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD APR PY 1995 VL 43 IS 4 BP 977 EP 983 DI 10.1109/22.375263 PN 2 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA QT617 UT WOS:A1995QT61700010 ER PT J AU SONI, T ZEIDLER, JR KU, WH AF SONI, T ZEIDLER, JR KU, WH TI BEHAVIOR OF THE PARTIAL CORRELATION-COEFFICIENTS OF A LEAST-SQUARES LATTICE FILTER IN THE PRESENCE OF A NONSTATIONARY CHIRP INPUT SO IEEE TRANSACTIONS ON SIGNAL PROCESSING LA English DT Article ID ADAPTIVE EQUALIZATION; ALGORITHMS; PERFORMANCE; NOISE AB This paper studies the performance of the a posteriori recursive least squares lattice filter in the presence of a nonstationary chirp signal, The forward and backward partial correlation (PARCOR) coefficients for a Wiener-Hopf optimal filter are shown to be complex conjugates for the general case of a nonstationary input with constant power, Such an optimal filter is compared to a minimum mean square error based least squares lattice adaptive filter, Expressions are found for the behavior of the first stage of the adaptive filter based on the least squares algorithm, For the general nth stage, the PARCOR coefficients of the previous stages are assumed to have attained Wiener-Hopf optimal steady state, The PARCOR coefficients of such a least squares adaptive filter are compared with the optimal coefficients for such a nonstationary input. The optimal lattice filter is seen to track a chirp input without any error, and the tracking lag in such an adaptive filter is due to the least squares update procedure, The expression for the least squares based PARCOR coefficients are found to contain two terms: a decaying convergence term due to the weighted estimation procedure and a tracking component that asymptotically approaches the optimal coefficient value, The fate of convergence is seen to depend inversely on the forgetting factor. The tracking lag of the filter is derived as a function of the rate of nonstationarity and the forgetting factor, It is shown that for a given chirp rate there is a threshold adaptation constant below which the total tracking error is negligible, For forgetting factors above this threshold, the error increases nonlinearly. Further, this threshold forgetting factor decreases with increasing chirp rate, Simulations are presented to validate the analysis. C1 USN,CTR COMMAND CONTROL & OCEAN SURVEILLANCE,DIV RDT&E,SAN DIEGO,CA 92152. UNIV CALIF SAN DIEGO,DEPT ELECT & COMP ENGN,LA JOLLA,CA 92093. RP SONI, T (reprint author), NASA,AMES RES CTR,STERLING SOFTWARE INC,MOFFETT FIELD,CA 94035, USA. NR 25 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 1053-587X J9 IEEE T SIGNAL PROCES JI IEEE Trans. Signal Process. PD APR PY 1995 VL 43 IS 4 BP 852 EP 863 DI 10.1109/78.376838 PG 12 WC Engineering, Electrical & Electronic SC Engineering GA QT098 UT WOS:A1995QT09800005 ER PT J AU VELUSAMY, K GARG, VK VIDYANATHAN, G AF VELUSAMY, K GARG, VK VIDYANATHAN, G TI FULLY-DEVELOPED FLOW AND HEAT-TRANSFER IN SEMIELLIPTIC DUCTS SO INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW LA English DT Article DE LAMINAR FLOW AND HEAT TRANSFER; SEMIELLIPTIC DUCTS; CONTROL VOLUME ANALYSIS ID LAMINAR-FLOW AB A control volume-based numerical solution is described for the fully developed laminar flaw and heat transfer in ducts of semi-elliptical cross section. Both an isothermal and a uniform axial heat flux condition on the duct walls have been considered. Numerical results for velocity and temperature profiles, friction factor, pressure defect, and Nusselt number are presented for a wide range of duct aspect ratios from 0.1 to 0.999. Comparison with earlier numerical results for the limiting case of semicircular duct and with analytical solution for fully elliptical ducts is excellent. For ducts in which the baseplate is on the major axis, friction factor and Nusselt number for the uniform heat flux condition increase as the aspect ratio decreases, with values for the lowest aspect ratio of 0.1 being about 25 percent larger than those for a semicircular duct. For ducts with the baseplate on the minor axis, all characteristics exhibit a nonmonotonic behavior with respect to the aspect ratio. While the maximum velocity and pressure defect exhibit a mild maximum for aspect ratio of 0.6, the friction factor and Nusselt number exhibit a minimum at the same aspect ratio. The ratio of Nusselt number to friction factor is higher for semi-elliptical ducts in comparison to that for other ducts, such as sinusoidal,circular segmental, and isosceles triangular ducts. C1 NASA,LEWIS RES CTR,DIV INTERNAL FLUID MECH,CLEVELAND,OH 44135. INDIRA GANDHI CTR ATOM RES,THERMAL HYDRAUL SECT,KALPAKKAM,TAMIL NADU,INDIA. NR 22 TC 18 Z9 18 U1 0 U2 4 PU BUTTERWORTH-HEINEMANN PI WOBURN PA 225 WILDWOOD AVE #UNITB PO BOX 4500, WOBURN, MA 01801-2084 SN 0142-727X J9 INT J HEAT FLUID FL JI Int. J. Heat Fluid Flow PD APR PY 1995 VL 16 IS 2 BP 145 EP 152 DI 10.1016/0142-727X(94)00019-9 PG 8 WC Thermodynamics; Engineering, Mechanical; Mechanics SC Thermodynamics; Engineering; Mechanics GA QT394 UT WOS:A1995QT39400009 ER PT J AU OTTERMAN, J BRAKKE, T MARSHAK, A AF OTTERMAN, J BRAKKE, T MARSHAK, A TI SCATTERING BY LAMBERTIAN-LEAVES CANOPY - DEPENDENCE ON LEAF-AREA PROJECTIONS SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID MODEL; INVERSION AB A single-scattering model is constructed for a canopy with Lambertian leaves. The azimuthal distribution of the leaves is represented by fractional abundances of the leaf-area in the cardinal directions with respect to the Sun. The canopy bi-directional reflectances are found to be controlled by the projections of the leaf-areas onto horizontal and vertical planes. The sum of the leaf-area projections onto the horizontal plane determines the reflectance to the zenith when the Sun is at the zenith. For a complete canopy this reflectance is [GRAPHICS] where w(xh) is the fractional projection onto the horizontal plane of leaf-area of leaf-category x, g(x) is the leaf reflectance (assumed equal to the leaf transmittance), and Psi(x) is the zenith angle of the leaf normal for this category. As the view and solar zenith angles deviate from the nadir, the change in the reflectance in the principal plane of the Sun is controlled by the difference in the leaf-area projections onto the vertical plane of the leaves with leaf-normals in opposite quadrants in the principal plane. When these two leaf-categories are identical (other than in their azimuths), a large region around the zenith exhibits the Lambertian viewing property, that is, the reflectance does not change with the view or illumination directions. Forward scattering and backscattering, which become intense when both the illumination zenith angle theta 0, and the view zenith angle theta v, are large (approach 90 degrees) while Psi is not small (or when Psi is large while theta 0, and theta v, are not small), are controlled by the slim of these two leaf-area projections. The reflectance has then the limiting value g sin Psi'(cot theta 0 + cot theta v), where g and Psi characterize the two leaf categories with normals in the principal plane. This expression represents a generalization of a result obtained for a field of thin vertical cylinders, C1 SCI SYST & APPLICAT INC,LANHAM,MD 20706. RP OTTERMAN, J (reprint author), NASA,GODDARD SPACE FLIGHT CTR,TERR PHYS LAB,910-4,GREENBELT,MD 20771, USA. RI Marshak, Alexander/D-5671-2012 NR 14 TC 4 Z9 4 U1 1 U2 1 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 1995 VL 16 IS 6 BP 1107 EP 1125 PG 19 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA QV907 UT WOS:A1995QV90700009 ER PT J AU LAPORTE, N JUSTICE, C KENDALL, J AF LAPORTE, N JUSTICE, C KENDALL, J TI MAPPING THE DENSE HUMID FOREST OF CAMEROON AND ZAIRE USING AVHRR SATELLITE DATA SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID LAND AB Central Africa contains the second largest contiguous rain forest in the world. The current state of this forest is poorly known. The most recent comprehensive national forest distribution maps of the central African region are from the period between 1950-1980 and are not representative of more recent forest degradation or conversion. In this study NOAA-AVHRR data at 1 km resolution have been used to develop current maps of the dense humid forest extent for Zaire and Cameroon. Preliminary estimates of the areal extent of the rain forest are made. Validation of the AVHRR maps is performed through comparison with high resolution satellite imagery (Landsat-MSS) and existing maps. Forest cover maps generated by this study are a fundamental step leading to multi-scale mapping and monitoring of global tropical forests. C1 NASA,GODDARD SPACE FLIGHT CTR,SCI SYST & APPLICAT INC,GREENBELT,MD 20771. RP LAPORTE, N (reprint author), UNIV MARYLAND,DEPT GEOG,COLLEGE PK,MD 20742, USA. NR 34 TC 44 Z9 44 U1 0 U2 2 PU TAYLOR & FRANCIS LTD LONDON PI LONDON PA ONE GUNDPOWDER SQUARE, LONDON, ENGLAND EC4A 3DE SN 0143-1161 J9 INT J REMOTE SENS JI Int. J. Remote Sens. PD APR PY 1995 VL 16 IS 6 BP 1127 EP 1145 PG 19 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA QV907 UT WOS:A1995QV90700010 ER PT J AU KIEFER, R YUE, JJ HINKLEY, JA AF KIEFER, R YUE, JJ HINKLEY, JA TI KINETIC MAPPING OF OXIDATIVE WEIGHT-LOSS IN POLYIMIDE COMPOSITES SO JOURNAL OF ADVANCED MATERIALS LA English DT Article AB Thermogravimetric analysis data on four families of thermoplastic polyimides and related materials were plotted according to the kinetic mapping procedure of Grayson and Fry. It was found that both the chemistry of the polymer backbone and the processing and sampling procedures affected the results. The most stable material tested was LaRC(TM)-8515 thermoplastic polyimide, which showed an activation energy of 183 kJ/mol and a pre-exponential frequency factor of 10(10.2) assuming first order kinetics. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP KIEFER, R (reprint author), COLL WILLIAM & MARY,WILLIAMSBURG,VA 23185, USA. NR 14 TC 4 Z9 4 U1 0 U2 0 PU SAMPE PUBLISHERS PI COVINA PA 1161 PARKVIEW DRIVE, COVINA, CA 91722 SN 1070-9789 J9 J ADV MATER JI J. Adv. Mater. PD APR PY 1995 VL 26 IS 3 BP 55 EP 59 PG 5 WC Materials Science, Multidisciplinary SC Materials Science GA QR372 UT WOS:A1995QR37200009 ER PT J AU WILLMAN, BM BOLES, WW MCKAY, DS ALLEN, CC AF WILLMAN, BM BOLES, WW MCKAY, DS ALLEN, CC TI PROPERTIES OF LUNAR SOIL SIMULANT JSC-1 SO JOURNAL OF AEROSPACE ENGINEERING LA English DT Article AB With the establishment of a lunar base, many tasks will require direct interaction between the in-situ lunar soil and a wide variety of instruments and implements. The individual tasks may be scientific in nature, or simply the manipulation of the lunar soil. To help fulfill the need for relatively large quantities of lunar soil simulant in researching these operations, Johnson Space Center has developed a new simulant called JSC-1. It is produced from a basaltic pyroclastic sheet deposit located in the San Francisco volcanic field near Flagstaff, Arizona (as reported by McKay et al. in 1993 and 1994). JSC-1 is a crushed, ground, and sieved material that was developed to have similar mechanical properties and characteristics of the lunar soil. Furthermore, this glass-rich basaltic ash can be used in chemical or mineralogical resource studies (as reported by McKay et al. in 1993 and 1994). The Lunar Soil Simulant Laboratory, at the Civil Engineering Department, at Texas A&M University, is responsible for analyzing, storing, and distributing this material to qualified researchers. Information regarding the availability of JSC-1 is provided at the end of the paper. The purpose of this paper is to assess JSC-1 as a close terrestrial analog of the lunar soil and to inform the research community of the availability of the new simulant. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. RP WILLMAN, BM (reprint author), TEXAS A&M UNIV,DEPT CIVIL ENGN,COLLEGE STN,TX 77843, USA. NR 20 TC 31 Z9 42 U1 0 U2 17 PU ASCE-AMER SOC CIVIL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0893-1321 J9 J AEROSPACE ENG JI J. Aerosp. Eng. PD APR PY 1995 VL 8 IS 2 BP 77 EP 87 DI 10.1061/(ASCE)0893-1321(1995)8:2(77) PG 11 WC Engineering, Aerospace; Engineering, Civil SC Engineering GA RZ834 UT WOS:A1995RZ83400001 ER PT J AU ELLISON, J AHMADI, G GRODSINSKY, C AF ELLISON, J AHMADI, G GRODSINSKY, C TI STOCHASTIC-MODEL FOR MICROGRAVITY EXCITATION SO JOURNAL OF AEROSPACE ENGINEERING LA English DT Article AB A simple stochastic method for generating synthetic orbital accelerations is proposed in this paper, The procedure is used to develop a stochastic model for the STS-40 orbital excitation. The method uses a filtered white-noise model that takes into account time evolutions of the amplitude and the frequency content of the original accelerogram. The probabilistic response spectra are generated and comparisons with those of the actual STS-40 orbital data are made to verify the model, The results indicate that significant properties of the original record are retained in the generated synthetic accelerations. This method is also employed to generate a stochastic model for the space station vibration environment. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP ELLISON, J (reprint author), CLARKSON UNIV,DEPT MECH & AEROSP ENGN,POTSDAM,NY 13699, USA. NR 12 TC 1 Z9 1 U1 0 U2 0 PU ASCE-AMER SOC CIVIL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2398 SN 0893-1321 J9 J AEROSPACE ENG JI J. Aerosp. Eng. PD APR PY 1995 VL 8 IS 2 BP 100 EP 106 DI 10.1061/(ASCE)0893-1321(1995)8:2(100) PG 7 WC Engineering, Aerospace; Engineering, Civil SC Engineering GA RZ834 UT WOS:A1995RZ83400003 ER PT J AU HINGHOFERSZALKAY, HG SAUSENGFELLEGGER, G GREENLEAF, JE AF HINGHOFERSZALKAY, HG SAUSENGFELLEGGER, G GREENLEAF, JE TI PLASMA-VOLUME WITH ALTERNATING TILTING - EFFECT OF FLUID INGESTION SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE MICROCIRCULATION; POSTURE; GRAVITATION; ISOTONIC; FLUID SHIFTS; INTERSTITIAL TISSUE ID CENTRAL VENOUS-PRESSURE; BODY NEGATIVE-PRESSURE; ELECTROLYTE TRANSPORT; SMALL-INTESTINE; BLOOD-VOLUME; HUMANS; RESPONSES; EXERCISE; PERMEABILITY; ABSORPTION AB The present study determines the effect of repeated 70 degrees head-up tilt (HUT) on plasma volume (PV) shifts by measuring blood density (ED), plasma density (PD), and hematocrit (Hct). Eight men (18-26 yr) underwent a predrink period with two supine (P1 and P3) and two HUT (P2 and P4) phases of 45 min each. At the end of P4 they drank 10 ml/kg body wt of isotonic (290 mosmol/kg) sodium chloride (Iso) or hypotonic (<10 mosmol/kg) unsweetened tea (Hypo) or nothing [control (Con)]. The following periods continued the supine (P5, P7)/upright (P6) sequence. ED and PD were measured from ear lobe blood; they were different (P < 0.05) between Con, Hypo, and Iso P6 and P7. The density of fluid that moved between intra- and extravascular compartments was 1,008.2 +/- 0.4 g/l and did not differ with test situations. In Con (P3, P5, P7), supine PV steadily decreased compared with P1 (P < 0.05). PV in P1, P2, and P3 of all treatments averaged 120 +/- 1, 101 +/- 1, and 115 +/- 1%, respectively, of PV in P4. Tilt-induced PV shifts ranged from -9.7 to -16.7% compared with PV during the respective previous phases. After drinking, PV increased (P < 0.05) above Con values at the end of P7 by 12.9% with Iso and by 6.6% with Hypo. Progressive hemoconcentration occurred in the nondrink supine periods; isotonic saline ingestion increased supine PV to Con level but did not stop or reverse the decrease of upright hemoconcentration. Upright blood and PD were not altered with repeated HUT, which resulted in decreased fluid loss in consecutive upright periods. This indicated that with repeated tilting, upright capillary pressure balance is achieved with attenuated PV loss. C1 AUSTRIAN SOC AEROSP MED,INST ADAPTAT & SPACE FLIGHT PHYIOL,A-8010 GRAZ,AUSTRIA. NASA,AMES RES CTR,HUMAN ENVIRONM PHYSIOL LAB,MOFFETT FIELD,CA 94035. RP HINGHOFERSZALKAY, HG (reprint author), KARL FRANZENS UNIV GRAZ,SCH MED,DEPT PHYSIOL,VOLUME REGULAT & SPACE MED GRP,HARRACHGASSE 21,A-8010 GRAZ,AUSTRIA. NR 28 TC 8 Z9 8 U1 0 U2 1 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD APR PY 1995 VL 78 IS 4 BP 1369 EP 1373 PG 5 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA QR546 UT WOS:A1995QR54600021 PM 7615444 ER PT J AU LANGHOFF, SR BAUSCHLICHER, CW AF LANGHOFF, SR BAUSCHLICHER, CW TI GLOBAL DIPOLE-MOMENT FUNCTION FOR THE X(1)SIGMA(+) GROUND-STATE OF CO SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CARBON-MONOXIDE; BASIS-SETS; BAND; COEFFICIENTS; STRENGTHS; LINES RP LANGHOFF, SR (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 29 TC 35 Z9 35 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 1995 VL 102 IS 13 BP 5220 EP 5225 DI 10.1063/1.469247 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QP515 UT WOS:A1995QP51500012 ER PT J AU STIEF, LJ NESBITT, FL PAYNE, WA KUO, SC TAO, W KLEMM, RB AF STIEF, LJ NESBITT, FL PAYNE, WA KUO, SC TAO, W KLEMM, RB TI RATE-CONSTANT AND REACTION CHANNELS FOR THE REACTION OF ATOMIC NITROGEN WITH THE ETHYL RADICAL SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID PHOTOELECTRON-SPECTROSCOPY; PHOTOIONIZATION SPECTRUM; TEMPERATURE-DEPENDENCE; VACUUM ULTRAVIOLET; IONIZATION-ENERGY; D2CN RADICALS; KINETIC DATA; DIODE-LASER; CHEMISTRY; COMBUSTION C1 BROOKHAVEN NATL LAB,DEPT APPL SCI,UPTON,NY 11973. COPPIN STATE COLL,DEPT NAT SCI,BALTIMORE,MD. RP STIEF, LJ (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 51 TC 27 Z9 27 U1 0 U2 2 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD APR 1 PY 1995 VL 102 IS 13 BP 5309 EP 5316 DI 10.1063/1.469257 PG 8 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QP515 UT WOS:A1995QP51500022 ER PT J AU MECHERIKUNNEL, A WEISS, M PENN, L AF MECHERIKUNNEL, A WEISS, M PENN, L TI THE ESTIMATION OF EMITTED AND REFLECTED ENERGY OVER THE CENTRAL PACIFIC USING METEOROLOGICAL PARAMETERS SO JOURNAL OF CLIMATE LA English DT Article ID EARTH RADIATION BUDGET; EXPERIMENT ERBE; CLOUD TYPE; CLIMATE; BALANCE AB The authors conducted a quantitative investigation of the relationship between meteorological parameters (chiefly cloud cover) and the principal components of the earth's radiation budget. The area of study is the tropical central Pacific, where considerable variation in cloudiness and flux was observed from 1985 to 1989. The observed variations were in response to the El Nino-Southern Oscillation event of 1987. International Satellite Cloud Climatology Project (ISCCP) C2 parameters were used as independent variables in the development of multiple linear models to predict Earth Radiation Budget Experiment (ERBE) outgoing longwave radiation (OLR) and shortwave (SW) fluxes. Net radiation estimates were obtained from OLR and SW predicted fluxes. The technique of all-subsets regression was used to determine which combination of ISCCP C2 parameters could best predict OLR and SW fluxes. The models were developed for the years 1985 and 1989 (non-ENSO years) and tested by both month and year on the years 1986 through 1988. Predicted fluxes were obtained for three 15 degrees latitude zones, north (7.5 degrees to 22.5 degrees N), central (7.5 degrees N to 7.5 degrees N), and south (7.5 degrees S to 22.5 degrees S). Over the 60 months of data, explained variances (R(2)) of over 90% for the development and test periods were typical. An increase in the accuracy of the OLR models was observed when noncloud variables were included. This accuracy improvement was most apparent when cloud amounts were either very low or very high and homogeneous. Biases (predicted-observed) were all less than 4 Wm(-2) and rms estimates were within the range of uncertainty for ERBE monthly mean flux estimates. Flux estimates based on linear models could serve as a means of extending long-term radiation balance datasets during intervals of time with limited satellite coverage. C1 RES & DATA SYST CORP,GREENBELT,MD. RP MECHERIKUNNEL, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,MAIL CODE 925,GREENBELT,MD 20771, USA. NR 19 TC 0 Z9 0 U1 0 U2 2 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 1995 VL 8 IS 4 BP 762 EP 772 DI 10.1175/1520-0442(1995)008<0762:TEOEAR>2.0.CO;2 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QV555 UT WOS:A1995QV55500008 ER PT J AU HELFAND, HM SCHUBERT, SD AF HELFAND, HM SCHUBERT, SD TI CLIMATOLOGY OF THE SIMULATED GREAT-PLAINS LOW-LEVEL JET AND ITS CONTRIBUTION TO THE CONTINENTAL MOISTURE BUDGET OF THE UNITED-STATES SO JOURNAL OF CLIMATE LA English DT Article ID GENERAL-CIRCULATION MODELS; DIURNAL-VARIATIONS; SLOPING TERRAIN; LAYER; PARAMETERIZATION; SENSITIVITY; CONVECTION; ABSORPTION; EQUATIONS; WINDS AB The Great Plains region of the United States is characterized by some of the most frequent and regular occurrences of a nocturnal low-level jet (LLJ). While the LLJ is generally confined to the lowest kilometer of the atmosphere, it may cover a substantial region of the Great Plains, and typically reaches maximum amplitudes of more than 20 m s(-1). A two-month, springtime simulation with the Goddard Earth Observing System (GEOS-1) atmospheric general circulation model (AGCM) has produced a Great Plains LLJ with a vertical and temporal structure, directionality, and climatological distribution that compare favorably with observations. The diurnal cycle of the low-level flow is dramatic and coherent over a subcontinental area that includes much of the western United States and northern Mexico. This cycle can be interpreted as the nightly intrusion of the anticyclonic, subtropical gyre (associated with the Bermuda high) into the North American continent as surface friction decreases. The AGCM also simulates a pair of northerly LLJ maxima off the California coast, which seem to correspond to observations of a so-called ''Baja Jet.'' Other apparently related diurnal variations extending well into the upper troposphere are documented and compared with observations. The time-averaged climatological picture of the low-level flow is dominated over land by the nocturnal phase of the diurnal cycle, in which surface friction is minimal and wind speeds are strongest. This pattern, with its zones of strong convergence, is characteristic of an unsteady, strongly forced flow. Over the open ocean, the mean low-level now is more reminiscent of a smooth, climatological pattern. Analysis of the simulated moisture budget for the continental United States reveals a horizontally confined; region of strong southerly moisture transport with a strong diurnal cycle in the region of the Great Plains LLJ, as has been found in observations of water vapor transport. The LLJ plays a key role in that budget by transporting almost one-third of all the moisture that enters the continental United States with most of the influx from the LLJ (slightly less than two-thirds of it) entering during the 12 nighttime hours. However, it is the mean flow pattern and not covariances associated with the diurnal cycle that contribute most significantly to the total time-mean moisture transport. Covariances on the synoptic and longer timescales contribute only about one-fifth of the total time-mean transport of moisture in the jet region, and covariances on the diurnal timescale are negative and negligible despite the strong diurnal signal in the wind. RP HELFAND, HM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, DATA ASSIMILAT OFF, CODE 9103, GREENBELT, MD 20771 USA. NR 54 TC 137 Z9 137 U1 0 U2 13 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 USA SN 0894-8755 J9 J CLIMATE JI J. Clim. PD APR PY 1995 VL 8 IS 4 BP 784 EP 806 DI 10.1175/1520-0442(1995)008<0784:COTSGP>2.0.CO;2 PG 23 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QV555 UT WOS:A1995QV55500010 ER PT J AU CHRISTY, JR SPENCER, RW MCNIDER, RT AF CHRISTY, JR SPENCER, RW MCNIDER, RT TI REDUCING NOISE IN THE MSU DAILY LOWER-TROPOSPHERIC GLOBAL TEMPERATURE DATASET SO JOURNAL OF CLIMATE LA English DT Article ID RADIOSONDE VALIDATION; PRECISION; ANOMALIES AB The daily global-mean values of the lower-tropospheric temperature determined from microwave emissions measured by satellites are examined in terms of their signal, noise, and signal-to-noise ratio. Daily and 30-day average noise estimates are reduced by almost 50% and 35%, respectively, by analyzing and adjusting (if necessary) for errors due to 1) missing data, 2) residual harmonics of the annual cycle unique to particular satellites, 3) lack of filtering, and 4) spurious trends. After adjustments, the decadal trend of the lower-tropospheric global temperature from January 1979 through February 1994 becomes -0.058 degrees C, or about 0.03 degrees C per decade cooler than previously calculated. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP CHRISTY, JR (reprint author), UNIV ALABAMA,EARTH SYST SCI LAB,HUNTSVILLE,AL 35899, USA. NR 12 TC 44 Z9 44 U1 0 U2 1 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 1995 VL 8 IS 4 BP 888 EP 896 DI 10.1175/1520-0442(1995)008<0888:RNITMD>2.0.CO;2 PG 9 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QV555 UT WOS:A1995QV55500017 ER PT J AU WILKINSON, S HINKLEY, JA AF WILKINSON, S HINKLEY, JA TI SIZE AND GEOMETRY-EFFECTS IN TRANSVERSE FLEXURAL TESTING OF UNIDIRECTIONAL GRAPHITE THERMOPLASTIC SO JOURNAL OF COMPOSITES TECHNOLOGY & RESEARCH LA English DT Article DE THERMOPLASTIC COMPOSITES; TRANSVERSE FLEX TEST; ADHESION; FIBER MATRIX INTERFACE STRENGTH ID COMPOSITES; MATRIX; INTERFACE; ADHESION AB Over 140 flex tests were conducted on IM7/polysulfone laminates to determine the effects of specimen dimensions and resin content on measured strength. The only statistically significant size effect found was a decrease in strength with increase of the total stressed volume. A Weibull parameter of 7.9 could be fit to the data. Recommendations were made for the use of the flex test to quantify resin/matrix adhesion. C1 COLL WILLIAM & MARY,APPL SCI PROGRAM,WILLIAMSBURG,VA 23187. NASA,LANGLEY RES CTR,COMPOSITES & POLYMERS BRANCH,HAMPTON,VA 23681. NR 22 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 0884-6804 J9 J COMPOS TECH RES JI J. Compos. Technol. Res. PD APR PY 1995 VL 17 IS 2 BP 84 EP 89 PG 6 WC Materials Science, Composites; Polymer Science SC Materials Science; Polymer Science GA QT220 UT WOS:A1995QT22000002 ER PT J AU VENKATAKRISHNAN, V AF VENKATAKRISHNAN, V TI CONVERGENCE TO STEADY-STATE SOLUTIONS OF THE EULER EQUATIONS ON UNSTRUCTURED GRIDS WITH LIMITERS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID HYPERBOLIC CONSERVATION-LAWS; HIGH-RESOLUTION SCHEMES; ALGORITHM; SOLVERS; SYSTEMS; MESHES AB This paper addresses the practical problem of obtaining convergence to steady state solutions of the Euler equations when limiters are used in conjunction with upwind schemes on unstructured grids. The base scheme forms a gradient and limits it by imposing monotonicity conditions in the reconstruction stage. It is shown by analysis in one dimension that such an approach leads to various schemes meeting total-variation-diminishing requirements in one dimension. In multiple dimensions these schemes produce steady-state solutions that are monotone and devoid of oscillations. However, convergence stalls after a few orders of reduction in the residual, A new limiter is introduced that is particularly suited for unstructured grid applications. When reduced to one dimension, it is shown that this limiter satisfies the standard theory. With this limiter, it is shown that converged steady-state solutions can be obtained. However, the solutions are not monotone. There appears to be a conflict between achieving convergence and monotone solutions with the higher order schemes that employ limiters in the framework presented. (C) 1995 Academic Press, Inc. RP VENKATAKRISHNAN, V (reprint author), NASA,AMES RES CTR,COMP SCI CORP,MS T045-1,MOFFETT FIELD,CA 94035, USA. NR 16 TC 262 Z9 273 U1 1 U2 11 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD APR PY 1995 VL 118 IS 1 BP 120 EP 130 DI 10.1006/jcph.1995.1084 PG 11 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA QT079 UT WOS:A1995QT07900010 ER PT J AU GEORGE, T PIKE, WT KHAN, MA KUZNIA, JN CHANGCHIEN, P AF GEORGE, T PIKE, WT KHAN, MA KUZNIA, JN CHANGCHIEN, P TI A MICROSTRUCTURAL COMPARISON OF THE INITIAL GROWTH OF ALN AND GAN LAYERS ON BASAL-PLANE SAPPHIRE AND SIC SUBSTRATES BY LOW-PRESSURE METALORGANIC CHEMICAL-VAPOR-DEPOSITION SO JOURNAL OF ELECTRONIC MATERIALS LA English DT Article DE ALN; GAN; HIGH RESOLUTION TRANSMISSION ELECTRON MICROSCOPY (HRTEM); INTERFACIAL BONDING; LOW PRESSURE METALORGANIC CHEMICAL VAPOR DEPOSITION (MOCVD); SAPPHIRE SUBSTRATES ID BUFFER LAYER; EPITAXY AB The initial growth by low pressure metalorganic chemical vapor deposition and subsequent thermal annealing of AlN and GaN epitaxial layers on SiC and sapphire substrates is examined using high resolution transmission electron microscopy and atomic force microscopy. Growth under low pressure conditions on sapphire substrates is significantly different from that reported for conventional (atmospheric pressure) conditions. Smooth, single crystal AlN and GaN layers were deposited on sapphire in the initial low temperature (600 degrees C) growth step. Interfacial banding and not lattice mismatch was found to be the determining factor for obtaining good crystallinity for the epitaxial layers as indicated by the growth results on SiC substrates. C1 APA OPT INC,BLAINE,MN 55434. RP GEORGE, T (reprint author), CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 7 TC 24 Z9 24 U1 1 U2 6 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0361-5235 J9 J ELECTRON MATER JI J. Electron. Mater. PD APR PY 1995 VL 24 IS 4 BP 241 EP 247 DI 10.1007/BF02659682 PG 7 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA QR224 UT WOS:A1995QR22400007 ER PT J AU NEUDECK, PG AF NEUDECK, PG TI PROGRESS IN SILICON-CARBIDE SEMICONDUCTOR ELECTRONICS TECHNOLOGY SO JOURNAL OF ELECTRONIC MATERIALS LA English DT Article DE POWER ELECTRONICS; SILICON CARBIDE ID CHEMICAL VAPOR-DEPOSITION; DEVICES; GROWTH AB Silicon carbide's demonstrated ability to function under extreme high-temperature, high-power, and/or high-radiation conditions is expected to enable significant enhancements to a far-ranging variety of applications and systems. However, improvements in crystal growth and device fabrication processes are needed before SiC-based devices and circuits can be scaled-up and incorporated into electronic systems. This paper surveys the present status of SiC-based semiconductor electronics and identifies areas where technological maturation is needed. The prospects for resolving these obstacles are discussed. Recent achievements include the monolithic realization of SiC integrated circuit operational amplifiers and digital logic circuits, as well as significant improvements to epitaxial and bulk crystal growth processes that impact the viability of this rapidly emerging technology. RP NEUDECK, PG (reprint author), NASA,LEWIS RES CTR,MS 77-1,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 51 TC 190 Z9 195 U1 0 U2 19 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0361-5235 J9 J ELECTRON MATER JI J. Electron. Mater. PD APR PY 1995 VL 24 IS 4 BP 283 EP 288 DI 10.1007/BF02659688 PG 6 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA QR224 UT WOS:A1995QR22400013 ER PT J AU LARKIN, DJ SRIDHARA, SG DEVATY, RP CHOYKE, WJ AF LARKIN, DJ SRIDHARA, SG DEVATY, RP CHOYKE, WJ TI HYDROGEN INCORPORATION IN BORON-DOPED 6H-SIC CVD EPILAYERS PRODUCED USING SITE-COMPETITION EPITAXY SO JOURNAL OF ELECTRONIC MATERIALS LA English DT Article DE BORON; HYDROGEN PASSIVATION; SILICON CARBIDE; SITE COMPETITION EPITAXY ID DEVICES; GROWTH; FILMS AB We report on the initial investigations of using site-competition epitaxy to control boron incorporation in chemical vapor deposition (CVD) 6H-SiC epilayers. Also reported herein is the detection of hydrogen in boron-doped CVD SiC epilayers and hydrogen-passivation of the boron-acceptors. Results from low temperature photoluminescence (LTPL) spectroscopy indicate that the hydrogen content increased as the capacitance-voltage (C-V) measured net hole concentration increased. Secondary ion mass spectrometry (SIMS) analysis revealed that the boron and the hydrogen incorporation both increased as the Si/C ratio was sequentially decreased within the CVD reactor during epilayer growth. Epilayers that were annealed at 1700 degrees C in argon no longer exhibited hydrogen-related LTPL lines, and subsequent SIMS analysis confirmed the outdiffusion of hydrogen from the boron-doped SiC epilayers. The C-V measured net hole concentration increased more than threefold as a result of the 1700 degrees C anneal, which is consistent with hydrogen passivation of the boron-acceptors. However, boron related LTPL lines were not observed before or after the 1700 degrees C anneal. C1 UNIV PITTSBURGH,DEPT PHYS & ASTRON,PITTSBURGH,PA 15260. RP LARKIN, DJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 26 TC 75 Z9 75 U1 0 U2 5 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0361-5235 J9 J ELECTRON MATER JI J. Electron. Mater. PD APR PY 1995 VL 24 IS 4 BP 289 EP 294 DI 10.1007/BF02659689 PG 6 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA QR224 UT WOS:A1995QR22400014 ER PT J AU POWELL, JA LARKIN, DJ ABEL, PB AF POWELL, JA LARKIN, DJ ABEL, PB TI SURFACE-MORPHOLOGY OF SILICON-CARBIDE EPITAXIAL-FILMS SO JOURNAL OF ELECTRONIC MATERIALS LA English DT Article DE EPITAXY; MORPHOLOGY; SILICON CARBIDE (SIC) ID 0001 6H-SIC WAFERS; GROWTH AB Silicon carbide (SiC) semiconductor technology has been advancing rapidly, but there are numerous crystal growth problems that need to be solved before SiC can reach its full,potential. Among these problems is a need for an improvement in the surface morphology of epitaxial films that are grown to produce device structures. Because of advantageous electrical properties, SiC development is shifting from the 6H to the 4H polytype. In this study of both 6H and 4H-SiC epilayers, atomic force microscopy and other techniques were used to characterize SiC epilayer surface morphology. Observed features included isolated growth pits a few micrometers in size in both polytypes and triangles (in 4H only) approximately 50 mu m in size for epilayers 3 mu m in thickness. Also observed in some epilayers were large steps with heights greater than 20 nm. We found that there are significant differences between the morphology of 6H and 4H epilayers grown under identical conditions. We were able to improve surface morphology by avoiding conditions that lead to excess silicon during the initial startup of the growth process. However, the observed morphological defect density in both 6H and 4H epilayers was still the order of 10(4) cm(-2) and varied widely from run to run. As expected, we found that morphological defects in the SiC substrates play a role in the formation of some epilayer surface features. RP POWELL, JA (reprint author), NASA,LEWIS RES CTR,MS 77-1,21000 BROOKPK RD,CLEVELAND,OH 44135, USA. NR 14 TC 71 Z9 71 U1 0 U2 14 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 0361-5235 J9 J ELECTRON MATER JI J. Electron. Mater. PD APR PY 1995 VL 24 IS 4 BP 295 EP 301 DI 10.1007/BF02659690 PG 7 WC Engineering, Electrical & Electronic; Materials Science, Multidisciplinary; Physics, Applied SC Engineering; Materials Science; Physics GA QR224 UT WOS:A1995QR22400015 ER PT J AU ARYA, VK HALFORD, GR AF ARYA, VK HALFORD, GR TI FINITE-ELEMENT ANALYSIS OF STRUCTURAL-ENGINEERING PROBLEMS USING A VISCOPLASTIC MODEL INCORPORATING 2 BACK STRESSES SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME LA English DT Article ID CREEP AB The feasibility of a viscoplastic model incorporating two back stresses and a drag strength is investigated for performing nonlinear finite element analyses of structural engineering problems. The model has recently been put forth by Freed and Walker. The feasibility of the viscoplastic model is demonstrated for nonlinear structural analyses by implementing the model into a finite element program and performing nonlinear finite element analyses for several uniaxial and multiaxial problems. Good agreement is shown to exist between the results obtained using the finite element implementation and those obtained experimentally. The advantages of using advanced viscoplastic models for performing nonlinear finite element analyses of structural components are indicated. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP ARYA, VK (reprint author), UNIV AKRON,DEPT MATH SCI,AKRON,OH 44325, USA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0742-4795 J9 J ENG GAS TURB POWER JI J. Eng. Gas. Turbines Power-Trans. ASME PD APR PY 1995 VL 117 IS 2 BP 377 EP 383 DI 10.1115/1.2814105 PG 7 WC Engineering, Mechanical SC Engineering GA QW733 UT WOS:A1995QW73300022 ER PT J AU ARNOLD, SM SALEEB, AF WILT, TE AF ARNOLD, SM SALEEB, AF WILT, TE TI A MODELING INVESTIGATION OF THERMAL AND STRAIN-INDUCED RECOVERY AND NONLINEAR HARDENING IN POTENTIAL BASED VISCOPLASTICITY SO JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article ID PLASTICITY; EQUATIONS; CREEP AB Specific forms for both the Gibb's and the complementary dissipation potentials were chosen such that a complete potential based multiaxial, isothermal, viscoplastic model was obtained. This model, in general, possesses three internal state variables (two scalars associated with dislocation density and one tenser associated with dislocation motion) both thermal and dynamic recovery mechanisms, and nonlinear kinematic hardening. This general model, although possessing associated flow and evolutionary laws, is shown to emulate three distinct classes of theories found in the literature, by modification of the driving threshold function F. A parametric study was performed on a specialized nondimensional multiaxial form containing only a single tensorial internal state variable (i.e., internal stress). The study was conducted with the idea of examining the impact of including a strain-induced recovery mechanism and the compliance operator, derived from the Gibb's potential, on the uniaxial and multiaxial response. One important finding was that inclusion of strain-induced recovery provided the needed flexibility in modeling stress-strain and creep response of metals at low homologous temperatures, without adversely affecting the high temperature response. Furthermore, for nonproportional loading paths, the inclusion of the compliance operator had a significant influence on the multiaxial response, but had no influence on either uniaxial or proportional load histories. C1 UNIV AKRON,DEPT CIVIL ENGN,AKRON,OH 44325. UNIV TOLEDO,NASA,TOLEDO,OH 43606. RP ARNOLD, SM (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 24 TC 18 Z9 18 U1 0 U2 1 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-4289 J9 J ENG MATER-T ASME JI J. Eng. Mater. Technol.-Trans. ASME PD APR PY 1995 VL 117 IS 2 BP 157 EP 167 DI 10.1115/1.2804523 PG 11 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA QW902 UT WOS:A1995QW90200004 ER PT J AU BONACUSE, PJ KALLURI, S AF BONACUSE, PJ KALLURI, S TI ELEVATED-TEMPERATURE AXIAL AND TORSIONAL FATIGUE BEHAVIOR OF HAYNES-188 SO JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY-TRANSACTIONS OF THE ASME LA English DT Article AB The results are reported for high-temperature axial and torsional low-cycle fatigue experiments performed at 760 degrees C in air on thin-walled tubular specimens of Haynes 188, a wrought cobalt-base superalloy. Data are also presented for mean coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 degrees C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 degrees C. This data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME Boiler and Pressure Vessel Code), Manson-Halford, Modified Multiaxiality Factor (proposed in this paper), Modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by root 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The Modified Multiaxiality Factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed. C1 NASA,LEWIS RES CTR,NYMA INC,CLEVELAND,OH 44135. RP BONACUSE, PJ (reprint author), USA,RES LAB,NASA,LEWIS RES CTR,VEHICLE PROPULS DIRECTORATE,CLEVELAND,OH 44135, USA. NR 14 TC 11 Z9 11 U1 3 U2 9 PU ASME-AMER SOC MECHANICAL ENG PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017 SN 0094-4289 J9 J ENG MATER-T ASME JI J. Eng. Mater. Technol.-Trans. ASME PD APR PY 1995 VL 117 IS 2 BP 191 EP 199 DI 10.1115/1.2804529 PG 9 WC Engineering, Mechanical; Materials Science, Multidisciplinary SC Engineering; Materials Science GA QW902 UT WOS:A1995QW90200009 ER PT J AU TSYGANENKO, NA AF TSYGANENKO, NA TI MODELING THE EARTHS MAGNETOSPHERIC MAGNETIC-FIELD CONFINED WITHIN A REALISTIC MAGNETOPAUSE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID BIRKELAND CURRENTS; GEOMAGNETIC-FIELD; QUANTITATIVE MODELS; RING CURRENT; MAGNETOTAIL; PARAMETERS; SHAPE; TAIL; PRESSURE; CDAW-9 AB Empirical data-based models of the magnetospheric magnetic field have been widely used during recent years. However, the existing models (Tsyganenko, 1987, 1989a) have three serious deficiencies: (1) an unstable ''de facto'' magnetopause, (2) a crude parametrization by the K-p index, and (3) inaccuracies in the equatorial magnetotail B-z values. This paper describes a new approach to the problem; the essential new features are (1) a realistic shape and size of the magnetopause, based on fits to a large number of observed crossings (allowing a parametrization by the solar wind pressure), (2) fully controlled shielding of tile magnetic field produced by all magnetospheric current systems, (3) new flexible representations for the tail and ring currents, and (4) a new ''directional'' criterion for fitting the model field to spacecraft data, providing improved accuracy for field line mapping. Results are presented from initial efforts to create models assembled from these modules and calibrated against spacecraft data sets. RP TSYGANENKO, NA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HUGHES STX CORP,EXTRATERR PHYS LAB,CODE 695,GREENBELT,MD 20771, USA. RI Tsyganenko, Nikolai/J-7377-2012 OI Tsyganenko, Nikolai/0000-0002-5938-1579 NR 50 TC 659 Z9 663 U1 2 U2 19 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 1995 VL 100 IS A4 BP 5599 EP 5612 DI 10.1029/94JA03193 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QR195 UT WOS:A1995QR19500003 ER PT J AU VASSILIADIS, D KLIMAS, AJ AF VASSILIADIS, D KLIMAS, AJ TI ON THE UNIQUENESS OF LINEAR MOVING-AVERAGE FILTERS FOR THE SOLAR WIND-AURORAL GEOMAGNETIC-ACTIVITY COUPLING SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID FIELD; OVAL AB The relation between the solar wind input to the magnetosphere, upsilon B-South, and the auroral geomagnetic index AL is modeled with two linear moving-average filtering methods: linear prediction filters and a driven harmonic oscillator in the form of an electric circuit, Although the response of the three-parameter oscillator is ''simpler'' than the filter's, the methods yield similar linear timescales and values of the prediction-observation correlation and the prediction chi(2). Further the filter responses obtained by the two methods are similar in their long-term features. In these aspects the circuit model is equivalent to linear prediction filtering. This poses the question of uniqueness and proper interpretation of detailed features of the filters such as response peaks. Finally, the variation of timescales and filter responses with the AL activity level is discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. UNIV SPACE RES ASSOC,GREENBELT,MD. NR 24 TC 11 Z9 11 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD APR 1 PY 1995 VL 100 IS A4 BP 5637 EP 5641 DI 10.1029/94JA03303 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QR195 UT WOS:A1995QR19500006 ER PT J AU CHANDLER, MO AF CHANDLER, MO TI OBSERVATIONS OF DOWNWARD MOVING O+ IN THE POLAR TOPSIDE IONOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID CLEFT ION FOUNTAIN; MASS-SPECTROMETER; MAGNETOSPHERE; WIND; PLASMA; MODEL; FLOW AB New investigations of the core ion motion within the high-latitude topside ionosphere and near-Earth magnetosphere, using data from the Dynamics Explorer retarding ion mass spectrometer (RIMS), reveal the existence of significant regions of downward moving O+. The occurrences of downgoing versus upgoing O+ are not clearly separable in terms of either solar zenith angle or Kp but are well distinguished by the direction of the z component of the interplanetary magnetic field (IMF). On average, downflow dominates when IMF B-z < 0, while upflow dominates for IMF B-z > 0. Combining cross-field convection velocities derived from an empirical convection electric field model with the observed parallel velocities yields a two-dimensional ion velocity field, This velocity field is consistent with a scenario which has O+ of cusp/cleft and auroral zone origin convecting into the polar cap and, because of the dominance of gravitational energy over the upward kinetic energy, falling back into the ionosphere. This provides additional confirmation of the results of studies of the cleft ion fountain. Estimates of the flux of O+ in the upflowing and downflowing regions for Lambda greater than or equal to 60 degrees give a total upflow of similar to 6 x 10(25) ions s(-1) for IMF B-z > 0 and total upflow and downflow of similar to 4 x 10(25) ions s(-1), and 1 X 10(25) ions s(-1), respectively, for IMF B-z < 0. In all cases the magnitude of the dayside outflow is consistent with previous work on upwelling ions. While the magnitudes vary for high and low Kp the ratios of upward to downward flow are roughly the same at similar to 1.7. The downflowing O+ shows a correlation with the magnitude of the outflow of light ions in the same region but the cause and effect of this relationship is not distinguishable. RP CHANDLER, MO (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,MS ES83,HUNTSVILLE,AL 35812, USA. NR 18 TC 37 Z9 37 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 1995 VL 100 IS A4 BP 5795 EP 5800 DI 10.1029/94JA03236 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QR195 UT WOS:A1995QR19500021 ER PT J AU VIERECK, RA MURAD, E PIKE, CP MENDE, SB SWENSON, GA ELGIN, JB BERNSTEIN, LS LUCID, S AF VIERECK, RA MURAD, E PIKE, CP MENDE, SB SWENSON, GA ELGIN, JB BERNSTEIN, LS LUCID, S TI O(S-1) 557.7 NM AND O(D-1) 630 NM EMISSIONS IN SHUTTLE THRUSTER PLUMES SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ENVIRONMENT; ORBITER; SYSTEM; GLOW AB Radiation resulting from interaction between the effluent cloud of a space shuttle thruster and the ambient atmosphere was observed with a spectrograph aboard the shuttle. The spectral measurements were made between 400 and 800 nm with a resolution of 3 nm. The primary emissions are identified as NO2, HNO, O(D-1), and O(S-1). These are the first observations of O(S-1) emission in the shuttle plume. These data are compared with previous measurements, and possible excitation mechanisms are discussed. The results are also compared with a Monte Carlo simulation of thruster plume-atmosphere interaction radiation. C1 PHILLIPS LAB,SPACECRAFT INTERACT BRANCH,BEDFORD,MA 01731. SPECTRAL SCI INC,WOBURN,MA 01803. NASA,LYNDON B JOHNSON SPACE CTR,ASTRONAUT OFF,HOUSTON,TX 77058. LOCKHEED RES & DEV DIV,PALO ALTO,CA 94304. NR 18 TC 6 Z9 6 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD APR 1 PY 1995 VL 100 IS A4 BP 5819 EP 5825 DI 10.1029/94JA03371 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QR195 UT WOS:A1995QR19500024 ER PT J AU UDDEN, MM DRISCOLL, TB PICKETT, MH LEACHHUNTOON, CS ALFREY, CP AF UDDEN, MM DRISCOLL, TB PICKETT, MH LEACHHUNTOON, CS ALFREY, CP TI DECREASED PRODUCTION OF RED-BLOOD-CELLS IN HUMAN-SUBJECTS EXPOSED TO MICROGRAVITY SO JOURNAL OF LABORATORY AND CLINICAL MEDICINE LA English DT Article ID ERYTHROPOIETIN AB The fetal-body red blood cell mass (RBCM) decreases during the first few days of spaceflight; however, the pathophysiology of ''spaceflight anemia'' noted on return to earth is poorly understood. In studies before, during, and after a 9-day mission we determined the rates of removal and replacement of RBCs by using chromium 51. The rate and efficiency of RBC production were assessed with iron 59. Serial measurements were made of plasma volume (PV), RBCM, serum ferritin level, and erythropoietin level. PV decreased within hours, resulting in an increased total body hematocrit during the first few days of the mission. Serum erythropoietin level decreased within 24 hours and remained low. Circulating RBCs disappeared at a normal rate during flight, but few new cells replaced those destroyed, resulting in a decrease in RBCM of 11% during the mission. After 22 hours in space, intramedullary formation of cells continued at near preflight levels as measured by erythron iron tumover. The coexistence of new cell formation in the bane marrow and failure of cells to be released into the blood is consistent with ineffective erythropoiesis. Microgravity causes blood located in gravity-dependent spaces to shift to a central volume. We conclude that the initial adaptation is a reduction in PV resulting in plethora. Increase in total body hematocrit causes a decrease in erythropoietin production. RBCM decreases because RBCs destroyed at a normal rate are not replaced. The normal erythron iron tumover and the rapidity of decrease in RBCM indicate that reduction in the release of new RBCs results from ineffective erythropoiesis. On return to 1 g, the gravity-dependent blood spaces are reestablished, resulting in ''anemia of spaceflight.'' C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. GULF COAST REG BLOOD CTR,HOUSTON,TX. RP UDDEN, MM (reprint author), BAYLOR COLL MED,DEPT MED,HOUSTON,TX 77030, USA. NR 21 TC 54 Z9 57 U1 0 U2 0 PU MOSBY-YEAR BOOK INC PI ST LOUIS PA 11830 WESTLINE INDUSTRIAL DR, ST LOUIS, MO 63146-3318 SN 0022-2143 J9 J LAB CLIN MED JI J. Lab. Clin. Med. PD APR PY 1995 VL 125 IS 4 BP 442 EP 449 PG 8 WC Medical Laboratory Technology; Medicine, General & Internal; Medicine, Research & Experimental SC Medical Laboratory Technology; General & Internal Medicine; Research & Experimental Medicine GA QQ631 UT WOS:A1995QQ63100005 PM 7706898 ER PT J AU JACOBSON, NS GOTOTSI, YG YOSHIMURA, M AF JACOBSON, NS GOTOTSI, YG YOSHIMURA, M TI THERMODYNAMIC AND EXPERIMENTAL-STUDY OF CARBON FORMATION ON CARBIDES UNDER HYDROTHERMAL CONDITIONS SO JOURNAL OF MATERIALS CHEMISTRY LA English DT Article ID COMPUTER-PROGRAM; EQUILIBRIUM; SOLGASMIX; WATER AB Thermodynamic analyses for the corrosion of SiC, TIG, TaC, NbC, WC and B4C in the temperature range 300-1000 degrees C in high-pressure steam have been conducted using a Gibbs energy minimization computer code, The calculated results are compared to experimental results for corrosion of these carbides in a hydrothermal fluid above the critical point. The formation of carbon has been predicted and observed for all these carbides, except B4C. Carbon is formed at low H2O:carbide molar ratios. Lower pressure also promotes carbon formation. For a high H2O:carbide molar ratio, the carbon will be oxidized to CO and CO2. The hydrothermal method can be used for producing carbon coatings of nanometre to micrometre thickness on the surface of carbides. C1 UNIV OSLO,CTR MAT RES,N-0371 OSLO,NORWAY. TOKYO INST TECHNOL,ENGN MAT RES LAB,YOKOHAMA,KANAGAWA 227,JAPAN. RP JACOBSON, NS (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Jacobson, Nathan/A-9411-2009; Yoshimura, Masahiro/H-5938-2011; OI Yoshimura, Masahiro/0000-0003-1810-0301; Gogotsi, Yury/0000-0001-9423-4032 NR 34 TC 47 Z9 47 U1 0 U2 7 PU ROYAL SOC CHEMISTRY PI CAMBRIDGE PA THOMAS GRAHAM HOUSE SCIENCE PARK MILTON ROAD, CAMBRIDGE, CAMBS, ENGLAND CB4 4WF SN 0959-9428 J9 J MATER CHEM JI J. Mater. Chem. PD APR PY 1995 VL 5 IS 4 BP 595 EP 601 DI 10.1039/jm9950500595 PG 7 WC Chemistry, Physical; Materials Science, Multidisciplinary SC Chemistry; Materials Science GA QT493 UT WOS:A1995QT49300009 ER PT J AU MUELLER, CH HOLLOWAY, PH BUDAI, JD MIRANDA, FA BHASIN, KB AF MUELLER, CH HOLLOWAY, PH BUDAI, JD MIRANDA, FA BHASIN, KB TI YBA2CU3O7-X FILMS ON OFF-AXIS Y-ZRO2 SUBSTRATES USING Y-ZRO2 OR Y2O3 BARRIER LAYERS SO JOURNAL OF MATERIALS RESEARCH LA English DT Article ID THIN-FILMS; STABILIZED ZRO2; GROWTH; ZIRCONIA; YTTRIA; SRTIO3 AB YBa2CU3O7-x (YBCO) and barrier layer films were deposited on single-crystal (Y2O3)(0.09)(ZrO2)(0.91) substrates cut between 3.6 and 35.7 degrees off-axis from the (001) planes. The barrier layers were (Y2O3)(0.065)(Y-ZrO2)(0.935)(Y-ZrO2), Y2O3, Of multilayered structures of Y-ZrO2 and Y2O3. X-ray diffraction showed that the Y-ZrO2 and Y2O3 barrier layers generally grew epitaxially on the off-axis substrates, with the (001) barrier layer film planes being parallel to those of the substrate, and the [100] directions being parallel. YBCO films deposited on Y2O3 barrier layers also showed epitaxy with the YBCO (001) planes being nearly parallel to the substrate (001) planes, even for miscuts up to 35.7 degrees. In contrast, the (001) planes of YBCO films deposited on Y-ZrO2 barrier layers were almost parallel to the substrate surface, not the (001) substrate planes. However, YBCO films on Y-ZrO2 films maintained particular in-plane epitaxial orientations with respect to the substrate. The YBCO full-width at half-maximum (FWHM) x-ray peaks were slightly narrower (0.8 degrees) on Y2O3 barrier layers than on Y-ZrO2 layers (1.3 degrees). The electrical resistivity versus temperature behavior of the YBCO/Y2O3 films was consistent with increased,grain boundary scattering as the degree of substrate miscut increased, whereas YBCO/Y-ZrO2 films' resistivities showed less sensitivity to substrate miscut, consistent with the loss of epitaxy. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. UNIV FLORIDA,DEPT MAT SCI & ENGN,GAINESVILLE,FL 32611. OAK RIDGE NATL LAB,DIV SOLID STATE,OAK RIDGE,TN 37831. RI Budai, John/R-9276-2016 OI Budai, John/0000-0002-7444-1306 NR 20 TC 5 Z9 5 U1 0 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 APR PY 1995 VL 10 IS 4 BP 810 EP 816 DI 10.1557/JMR.1995.0810 PG 7 WC Materials Science, Multidisciplinary SC Materials Science GA QN591 UT WOS:A1995QN59100005 ER PT J AU BANKS, HT SMITH, RC AF BANKS, HT SMITH, RC TI WELL-POSEDNESS OF A MODEL FOR STRUCTURAL ACOUSTIC COUPLING IN A CAVITY ENCLOSED BY A THIN CYLINDRICAL-SHELL SO JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS LA English DT Article ID ACTIVE CONTROL; RADIATION; SYSTEMS; NOISE AB A fully coupled mathematical model describing the interactions between a vibrating thin cylindrical shell and an enclosed acoustic field is presented. Because the model will ultimately be used in control applications involving piezoceramic actuators, the loads and material contributions resulting from piezoceramic patches bonded to the shell are included in the discussion. Theoretical and computational issues lead to the consideration of a weak form of the modeling set of partial differential equations (PDEs) and through the use of a semigroup formulation, well-posedness results for the system model are obtained. (C) 1995 Academic Press, Inc. C1 IOWA STATE UNIV SCI & TECHNOL,DEPT MATH,AMES,IA 50011. NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. RP BANKS, HT (reprint author), N CAROLINA STATE UNIV,CTR RES SCI COMPUTAT,RALEIGH,NC 27695, USA. NR 27 TC 14 Z9 14 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0022-247X J9 J MATH ANAL APPL JI J. Math. Anal. Appl. PD APR 1 PY 1995 VL 191 IS 1 BP 1 EP 25 PG 25 WC Mathematics, Applied; Mathematics SC Mathematics GA QQ883 UT WOS:A1995QQ88300001 ER PT J AU FRIEDL, RR BIRK, M OH, JJ COHEN, EA AF FRIEDL, RR BIRK, M OH, JJ COHEN, EA TI THE ROTATIONAL SPECTRUM AND MOLECULAR-STRUCTURE OF CHLORINE CHLORATE SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID GAS-PHASE; SELF-REACTION; PHOTOLYSIS; CLO; PERCHLORATE; DIOXIDE; NITRATE; CLCLO2; CL2O2; OCLO AB Cl2O3 has been identified as a product of the ClO + OClO + M reaction at 220 K using submillimeter spectroscopy of the reaction products in a flowing gas mixture. The spectra of all four Cl isotopic species have been observed in the 415-436 GHz region. Selected transitions have also been measured at frequencies down to 209 GHz. The rotational and centrifugal distortion constants have been determined for all four species. The quadrupole splittings have been fitted for the main species. Structural parameters similar to those of other chlorine oxides have been derived from the rotational constants. These and the quadrupole coupling constants are consistent with those expected from a chlorine chlorate structure with no planes of symmetry. Structures which satisfy the requirement inferred from published infrared data that the Cl=O bonds must be shorter than those in OClO must all have long single bonds between the ClO and OClO portions of the molecule. (C) 1995 Academic Press, Inc. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 18 TC 44 Z9 44 U1 0 U2 5 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD APR PY 1995 VL 170 IS 2 BP 383 EP 396 DI 10.1006/jmsp.1995.1079 PG 14 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA QT231 UT WOS:A1995QT23100008 ER PT J AU ANGEL, PW HANN, RE COOPER, AR AF ANGEL, PW HANN, RE COOPER, AR TI THERMAL HISTORY EFFECTS ON ELECTRICAL RELAXATION AND CONDUCTIVITY FOR POTASSIUM SILICATE GLASS WITH LOW ALKALI CONCENTRATIONS SO JOURNAL OF NON-CRYSTALLINE SOLIDS LA English DT Article ID DIELECTRIC-RELAXATION; IONIC-CONDUCTIVITY; DISORDERED SOLIDS; TRACER DIFFUSION; AC CONDUCTION; OXIDE GLASSES; ACTIVATION; MODEL AB Electrical response measurements from 10 Hz to 100 Wt between 120 and 540 degrees C were made on potassium silicate glasses with alkali oxide contents of 2, 3, 5 and 10 mol%. Glasses with low alkali content were chosen to reduce the Coulombic interactions between alkali ions to the point that frozen structural effects from the silica network on the electrical response could be observed. Conductivity and electrical relaxation responses for both annealed and quenched glasses of the same composition were compared. Lower de conductivity, sigma(dc), activation energies were measured for the quenched glass than for the annealed glasses. All of the glasses exhibited Arrhenius behavior in the log sigma(dc) against 1/T plots. A sharp decrease in sigma(dc) was observed for glasses containing K2O concentrations of 5 mol% or less. The frequency at which a maximum occurs, f(max), in the modulus loss, M'', plots, when plotted against 1/T, exhibited Arrhenius behavior for both annealed and quenched samples. The activation energies for these plots closely agreed with the sigma(dc) activation energies. A sharp increase in activation energy was observed for sigma(dc) and f(max) as the potassium oxide concentration decreased. Changes in the electrical response are attributed to structural effects due to different alkali concentrations. C1 CASE WESTERN RESERVE UNIV,DEPT MAT SCI & ENGN,CLEVELAND,OH 44106. RP ANGEL, PW (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 34 TC 9 Z9 9 U1 0 U2 2 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0022-3093 J9 J NON-CRYST SOLIDS JI J. Non-Cryst. Solids PD APR PY 1995 VL 183 IS 3 BP 277 EP 289 DI 10.1016/0022-3093(94)00588-5 PG 13 WC Materials Science, Ceramics; Materials Science, Multidisciplinary SC Materials Science GA QV732 UT WOS:A1995QV73200007 ER PT J AU CHATTERJEE, S GILBERT, JR LONG, FJE SCHREIBER, R TENG, SH AF CHATTERJEE, S GILBERT, JR LONG, FJE SCHREIBER, R TENG, SH TI GENERATING LOCAL ADDRESSES AND COMMUNICATION SETS FOR DATA-PARALLEL PROGRAMS SO JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING LA English DT Article AB Generating local addresses and communication sets is an important issue in distributed-memory implementations of data-parallel languages such as High Performance Fortran. We demonstrate a storage scheme for an array A affinely aligned to a template that is distributed across p processors with a cyclic(k) distribution that does not waste any storage, and show that, under this storage scheme, the local memory access sequence of any processor for a computation involving the regular section A(l:h:s) is characterized by a finite state machine of at most k states. We present fast algorithms for computing the essential information about these state machines, and we extend the framework to handle multidimensional arrays. We also show how to generate communication sets using the state machine approach. Performance results show that this solution requires very little runtime overhead and acceptable preprocessing time. (C) 1995 Academic Press, Inc. C1 SYST ENGN ASSOCIATES,SAN DIEGO,CA 92109. MIT,DEPT MATH,CAMBRIDGE,MA 02139. XEROX CORP,PALO ALTO RES CTR,COMP SCI LAB,PALO ALTO,CA 94304. RP CHATTERJEE, S (reprint author), NASA,AMES RES CTR,ADV COMP SCI RES INST,MAIL STOP T27A-1,MOFFETT FIELD,CA 94035, USA. NR 15 TC 52 Z9 53 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0743-7315 J9 J PARALLEL DISTR COM JI J. Parallel Distrib. Comput. PD APR 1 PY 1995 VL 26 IS 1 BP 72 EP 84 DI 10.1006/jpdc.1995.1049 PG 13 WC Computer Science, Theory & Methods SC Computer Science GA QV520 UT WOS:A1995QV52000007 ER PT J AU WHITSON, PA PUTCHA, L CHEN, YM BAKER, E AF WHITSON, PA PUTCHA, L CHEN, YM BAKER, E TI MELATONIN AND CORTISOL ASSESSMENT OF CIRCADIAN SHIFTS IN ASTRONAUTS BEFORE FLIGHT SO JOURNAL OF PINEAL RESEARCH LA English DT Article DE BRIGHT LIGHT; URINE; SALIVA; LIGHT-DARK CYCLE; ASTRONAUTS; SPACE SHUTTLE ID SLEEP-WAKE CYCLE; BRIGHT LIGHT; SALIVARY CORTISOL; WORK; RHYTHMS; PLASMA; EXPOSURE; TEMPERATURE; RADIOIMMUNOASSAY; SUPPRESSION AB Melatonin and cortisol were measured in saliva and urine samples to assess the effectiveness of a 7-day protocol combining bright-light exposure with sleep shifting in eliciting a 12-hr phase-shift delay in eight U.S. Space Shuttle astronauts before launch. Baseline acrophases for 15 control subjects with normal sleep-wake cycles were as follows: cortisol (saliva) at 0700 (0730 in urine); melatonin (saliva) at 0130 (6-hydroxymelatonin sulfate at 0230 in urine). Acrophases of the astronaut group fell within 2.5 hr of these values before the treatment protocols were begun. During the bright-light and sleep-shifting treatments, both absolute melatonin production and melatonin rhythmicity were diminished during the first 3 treatment days; total daily cortisol levels remained constant throughout the treatment. By the fourth to sixth day of the 7-day protocol, seven of the eight crew members showed phase delays in all four measures that fell within 2 hr of the expected 11- to 12-hr shift. Although cortisol and melatonin rhythms each corresponded with the phase shift, the rhythms in these two hormones did not correspond with each other during the transition. C1 NASA,LYNDON B JOHNSON SPACE CTR,ASTRONAUT OFF,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX. RP WHITSON, PA (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV MED SCI,MAIL CODE SD,HOUSTON,TX 77058, USA. NR 36 TC 20 Z9 23 U1 0 U2 3 PU MUNKSGAARD INT PUBL LTD PI COPENHAGEN PA 35 NORRE SOGADE, PO BOX 2148, DK-1016 COPENHAGEN, DENMARK SN 0742-3098 J9 J PINEAL RES JI J. Pineal Res. PD APR PY 1995 VL 18 IS 3 BP 141 EP 147 DI 10.1111/j.1600-079X.1995.tb00152.x PG 7 WC Endocrinology & Metabolism; Neurosciences; Physiology SC Endocrinology & Metabolism; Neurosciences & Neurology; Physiology GA RG018 UT WOS:A1995RG01800004 PM 7562371 ER PT J AU BAUER, A GODON, M CARLIER, J MA, Q AF BAUER, A GODON, M CARLIER, J MA, Q TI WATER-VAPOR ABSORPTION IN THE ATMOSPHERIC WINDOW AT 239 GHZ SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID LINE-SHAPE THEORY; TEMPERATURE-DEPENDENCE; PERTURBER DEPENDENCES; CONTINUUM ABSORPTION; INFRARED-ABSORPTION; FAR WINGS; 183 GHZ; ATTENUATION; MILLIMETER; MM AB Absolute absorption rates of pure water vapor and mixtures of water vapor and nitrogen have been measured in the atmospheric window at 239 GHz. The dependence on pressure as well as temperature has been obtained. The experimental data are compared with several theoretical or empirical models, and satisfactory agreement is obtained with the models involving a continuum; in the case of pure water vapor, the continuum contribution based upon recent theoretical developments gives good results. The temperature dependence is stronger than that proposed in a commonly used atmospheric transmission model. C1 COLUMBIA UNIV,DEPT APPL PHYS,NEW YORK,NY 10025. NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. RP BAUER, A (reprint author), UNIV LILLE 1,SPECT HERTZIENNE LAB,CNRS,UNITE RECH,F-59655 VILLENEUVE DASCQ,FRANCE. NR 75 TC 22 Z9 22 U1 0 U2 5 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD APR PY 1995 VL 53 IS 4 BP 411 EP 423 DI 10.1016/0022-4073(95)90016-0 PG 13 WC Optics; Spectroscopy SC Optics; Spectroscopy GA RA312 UT WOS:A1995RA31200006 ER PT J AU POOVENDRAN, R DORBAND, JE YAGLE, AE AF POOVENDRAN, R DORBAND, JE YAGLE, AE TI AN ALGORITHM FOR FORWARD AND INVERSE SCATTERING IN TIME-DOMAIN SO JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA LA English DT Article C1 NASA,GODDARD SPACE FLIGHT CTR,HSTX,GREENBELT,MD 20771. UNIV MICHIGAN,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109. NR 8 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 0001-4966 J9 J ACOUST SOC AM JI J. Acoust. Soc. Am. PD APR PY 1995 VL 97 IS 4 BP 2021 EP 2027 DI 10.1121/1.411993 PG 7 WC Acoustics; Audiology & Speech-Language Pathology SC Acoustics; Audiology & Speech-Language Pathology GA QR369 UT WOS:A1995QR36900001 ER PT J AU ECKEL, AJ CAWLEY, JD AF ECKEL, AJ CAWLEY, JD TI OXIDATION-KINETICS OF A CONTINUOUS CARBON PHASE IN A NONREACTIVE MATRIX SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID SIC-FIBER; COMPOSITES AB Analytical solutions of and experimental results on the oxidation kinetics of carbon in a pore are presented. Reaction rate, reaction sequence, oxidant partial pressure, total system pressure, pore/crack dimensions, and temperature are analyzed with respect to the influence of each on an overall linear-parabolic rate relationship. Direct measurement of carbon recession is performed using two microcomposite model systems oxidized in the temperature range of 700 degrees to 1200 degrees C, and for times to 35 h. Experimental results are evaluated using the derived analytical solutions. Implications on the oxidation resistance of continuous-fiber-reinforced ceramic-matrix composites containing a carbon constituent are discussed. C1 CASE WESTERN RESERVE UNIV,CLEVELAND,OH 44106. UNIVERSAL ENERGY SYST INC,DAYTON,OH 45432. RP ECKEL, AJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 23 TC 57 Z9 57 U1 0 U2 1 PU AMER CERAMIC SOC 735 CERAMIC PLACE PI WESTERVILLE PA PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD APR PY 1995 VL 78 IS 4 BP 972 EP 980 DI 10.1111/j.1151-2916.1995.tb08424.x PG 9 WC Materials Science, Ceramics SC Materials Science GA QT907 UT WOS:A1995QT90700021 ER PT J AU OPILA, E AF OPILA, E TI INFLUENCE OF ALUMINA REACTION TUBE IMPURITIES ON THE OXIDATION OF CHEMICALLY-VAPOR-DEPOSITED SILICON-CARBIDE SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Note ID SINGLE-CRYSTAL SILICON; NITRIDE AB Pure coupons of chemically vapor deposited (CVD) SiC were oxidized for 100 h in dry flowing oxygen at 1300 degrees C. The oxidation kinetics were monitored using thermogravimetry (TGA). The experiments were first performed using high-purity alumina reaction tubes, The experiments were then repeated using fused quartz reaction tubes. Differences in oxidation kinetics, scale composition, and scale morphology were observed. These differences were attributed to impurities in the alumina tubes, Investigators interested in high-temperature oxidation of silica formers should be aware that high-purity alumina can have significant effects on experimental results. C1 NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. RP OPILA, E (reprint author), CLEVELAND STATE UNIV, DEPT CHEM ENGN, CLEVELAND, OH 44115 USA. NR 12 TC 77 Z9 79 U1 0 U2 4 PU WILEY-BLACKWELL PI MALDEN PA COMMERCE PLACE, 350 MAIN ST, MALDEN 02148, MA USA SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD APR PY 1995 VL 78 IS 4 BP 1107 EP 1110 DI 10.1111/j.1151-2916.1995.tb08449.x PG 4 WC Materials Science, Ceramics SC Materials Science GA QT907 UT WOS:A1995QT90700046 ER PT J AU Ham, JA Gardner, CK Tischler, MB AF Ham, JA Gardner, CK Tischler, MB TI Flight-testing and frequency-domain analysis for rotorcraft handling qualities SO JOURNAL OF THE AMERICAN HELICOPTER SOCIETY LA English DT Article AB A demonstration of frequency-domain flight-testing techniques and analysis was performed on a U.S. Army OH-58D helicopter in support of the OH-58D Airworthiness and Flight Characteristics Evaluation and of the Army's development and ongoing review of Aeronautical Design Standard 33C, Handling Qualities Requirements for Military Rotorcraft. Hover and forward flight (60 kn) tests were conducted in I flight hour by Army experimental test pilots. Further processing of the hover data generated a complete database of velocity, angular-rate, and acceleration-frequency responses to control inputs. A joint effort was then undertaken by the Airworthiness Qualification Test Directorate and the U.S. Army Aeroflightdynamics Directorate to derive handling-quality information from the frequency-response database. A significant amount of information could be extracted from the frequency. domain database using a variety of approaches. This report documents numerous results that have been obtained from the simple frequency-domain tests; in many areas, these results provide more insight into the aircraft dynamics that affect handling qualities than do traditional flight tests. The handling-quality results include ADS-33C bandwidth and phase-delay calculations, vibration spectral determinations, transfer-function models to examine single-axis results, and a six-degree-of-freedom fully coupled state-space model. The ability of this model to accurately predict aircraft responses was verified using data from pulse inputs. This report also documents the frequency-sweep flight-test technique and data analysis used to support the tests. C1 Test Directorate, Airworthiness Qualificat, Edwards AFB, CA 93523 USA. USA, Aeroflightdynam Directorate, ATCOM, Ames Res Ctr, Moffett Field, CA USA. RP Ham, JA (reprint author), Test Directorate, Airworthiness Qualificat, Edwards AFB, CA 93523 USA. NR 16 TC 6 Z9 7 U1 0 U2 2 PU AMER HELICOPTER SOC INC PI ALEXANDRIA PA 217 N WASHINGTON ST, ALEXANDRIA, VA 22314 USA SN 0002-8711 J9 J AM HELICOPTER SOC JI J. Am. Helicopter Soc. PD APR PY 1995 VL 40 IS 2 BP 28 EP 38 PG 11 WC Engineering, Aerospace SC Engineering GA V3034 UT WOS:000169111900004 ER PT J AU KOCH, SE MCQUEEN, JT KARYAMPUDI, VM AF KOCH, SE MCQUEEN, JT KARYAMPUDI, VM TI A NUMERICAL STUDY OF THE EFFECTS OF DIFFERENTIAL CLOUD COVER - ON COLD FRONTAL STRUCTURE AND DYNAMICS SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID PLANETARY BOUNDARY-LAYER; ATMOSPHERIC FRONTOGENESIS MODELS; ALONG-STREAM CIRCULATIONS; MOIST SYMMETRIC STABILITY; LOW-LEVEL STRUCTURE; POTENTIAL VORTICITY; MESOSCALE CIRCULATIONS; HEAT-FLUX; SIMULATION; RAINBANDS AB The effects of sensible heating and momentum mixing on the low-level structure and dynamics of a two-dimensional cold front are studied with a hydrostatic primitive equation model. Effects of inhomogeneous heating arising from a contrast in low-level cloud cover across the front are emphasized. The relative importance of grid resolution and the choice of method for parameterizing planetary boundary layer (PBL) processes in the model are also examined. Frontal updraft dynamics are studied in terms of the following inquiries: (a) the relative importance of turbulent momentum transport, differential sensible heating, and the reduction in static stability in the heated region ahead of the front; (b) the nature of the interaction between the adiabatic, semigeostrophic frontal circulation and the thermally forced circulation; and (c) possible roles played by dry symmetric instability and density current dynamics. The terms in the frontogenesis and divergence budget equations are computed to determine the relative roles played by the various physical and dynamical processes in generating the frontal secondary circulation system. A strong, narrow updraft jet forms in the presence of uniform sensible heating across the front. Although the greatest impact on frontogenesis occurs as a response to the reduction in static stability resulting from uniform sensible heating, additional forcing results from the nonlinear interaction between the adiabatic frontal circulation and the thermally forced circulation arising from a cross-front gradient in heating (due to the introduction of an overcast low cloud deck behind the front). The relative importance of inhomogeneous heating, however, increases with the grid resolution and the use of a multilevel treatment in place of bulk mixed-layer PBL models. Numerical experiments reveal that symmetric instability does not create the updraft jet, despite the development of negative potential vorticity ahead of the surface cold front. Highly unbalanced dynamics and a density current-like ''feeder flow'' behind the cold front are strongly indicated in the presence of sensible heating effects. Budget analyses show that the frontogenetical effect of sensible heating is only indirectly important through its strengthening of the confluence (convergence) field. The nonlinear and unbalanced ageostrophic vorticity terms in the divergence budget equation exert the strongest controls on the development of the updraft jet when sensible heating is nonuniform. These results suggest that differential cloud cover across cold fronts may promote the development of frontal squall lines. Nonhydrostatic models that include explicit prognostic equations for microphysics and use improved parameterization of boundary layer fluxes in the presence of clouds are needed to more fully address this possibility. C1 NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, STX CORP, GREENBELT, MD 20771 USA. NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, SSAI INC, GREENBELT, MD 20771 USA. RP N CAROLINA STATE UNIV, DEPT MARINE EARTH & ATMOSPHER SCI, BOX 8208, RALEIGH, NC 27695 USA. NR 81 TC 37 Z9 37 U1 0 U2 0 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 APR 1 PY 1995 VL 52 IS 7 BP 937 EP 964 DI 10.1175/1520-0469(1995)052<0937:ANSOTE>2.0.CO;2 PG 28 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QT709 UT WOS:A1995QT70900010 ER PT J AU WALCH, SP AF WALCH, SP TI COMPUTED POTENTIAL-ENERGY SURFACES AND MINIMUM ENERGY PATHWAYS FOR CHEMICAL-REACTIONS SO JOURNAL OF THE CHINESE CHEMICAL SOCIETY LA English DT Article DE POTENTIAL ENERGY SURFACES; MINIMUM ENERGY PATHWAYS; COMPLETELY ACTIVE SPACE SCF; INTERNALLY CONTRACTED CI; NOX; SOOT ID CONFIGURATION-INTERACTION CALCULATIONS; GAUSSIAN-BASIS SETS; REACTION CH(X2-PI)+N2(X1-SIGMA-G+)->HCN(X1-SIGMA+)+N(4S); THEORETICAL CHARACTERIZATION; MECHANISM; ATOMS; COMBUSTION; CHEMISTRY; 1ST-ROW; POINTS AB Computed potential energy surfaces are often required for computation of such observables as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method with the Dunning correlation consistent basis sets to obtain accurate energetics, gives useful results for a number of chemically important systems. Applications to complex reactions leading to NOx and soot formation in hydrocarbon combustion are discussed. RP WALCH, SP (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MS 230-3,MOFFETT FIELD,CA 94035, USA. NR 34 TC 0 Z9 0 U1 2 U2 2 PU CHINESE CHEM SOC PI TAIPEI PA PO BOX 609, TAIPEI 10099, TAIWAN SN 0009-4536 J9 J CHIN CHEM SOC-TAIP JI J. Chin. Chem. Soc. PD APR PY 1995 VL 42 IS 2 BP 221 EP 231 PG 11 WC Chemistry, Multidisciplinary SC Chemistry GA QW392 UT WOS:A1995QW39200015 ER PT J AU KURTZE, DA HONG, DC AF KURTZE, DA HONG, DC TI SMALL AMPLITUDE CELLS IN DIRECTIONAL VISCOUS FINGERING SO JOURNAL OF THE KOREAN PHYSICAL SOCIETY LA English DT Article ID PARITY-BREAKING TRANSITIONS; SAFFMAN-TAYLOR PROBLEM; PATTERN SELECTION; HYDRODYNAMIC SYSTEMS; MODULATED PATTERNS; CRYSTAL-GROWTH; SOLIDIFICATION; PROPAGATION; MODEL; INSTABILITIES AB We study the small-amplitude steady-state cellular patterns which occur in directional viscous fingering. We carry out a weakly nonlinear analysis for a general gap profile and show that when the capillary number is above the threshold for instability of a straight contact line, there exists a continuum of possible small-amplitude cellular steady-states. We also discuss the relation between the response of the front to perturbations and the problem of wavelength selection. In particular, we show how one might search for the preferred state by perturbing the front and examining its response. C1 N DAKOTA STATE UNIV, DEPT PHYS, FARGO, ND 58105 USA. NASA, LEWIS RES CTR, CLEVELAND, OH 44135 USA. LEHIGH UNIV, DEPT PHYS, BETHLEHEM, PA 18015 USA. NR 42 TC 1 Z9 1 U1 1 U2 2 PU KOREAN PHYSICAL SOC PI SEOUL PA 635-4, YUKSAM-DONG, KANGNAM-KU, SEOUL 135-703, SOUTH KOREA SN 0374-4884 EI 1976-8524 J9 J KOREAN PHYS SOC JI J. Korean Phys. Soc. PD APR PY 1995 VL 28 IS 2 BP 178 EP 187 PG 10 WC Physics, Multidisciplinary SC Physics GA QT250 UT WOS:A1995QT25000009 ER PT J AU SIEGEL, R AF SIEGEL, R TI TRANSIENT EMITTANCE LIMIT FOR COOLING A SEMITRANSPARENT RADIATING LAYER SO JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER LA English DT Note RP SIEGEL, R (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 4 TC 3 Z9 3 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0887-8722 J9 J THERMOPHYS HEAT TR JI J. Thermophys. Heat Transf. PD APR-JUN PY 1995 VL 9 IS 2 BP 373 EP 375 DI 10.2514/3.673 PG 3 WC Thermodynamics; Engineering, Mechanical SC Thermodynamics; Engineering GA QT307 UT WOS:A1995QT30700028 ER PT J AU BARNES, NP AF BARNES, NP TI LIDAR SYSTEMS SHED LIGHT AN ENVIRONMENTAL-STUDIES SO LASER FOCUS WORLD LA English DT Article RP BARNES, NP (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 0 TC 2 Z9 2 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 APR PY 1995 VL 31 IS 4 BP 87 EP & PG 0 WC Optics SC Optics GA QT088 UT WOS:A1995QT08800020 ER PT J AU BARNES, NP MURRAY, M AF BARNES, NP MURRAY, M TI TUNABLE NONLINEAR MATERIAL SHOWS PROMISE FOR MIDINFRARED REMOTE-SENSING SO LASER FOCUS WORLD LA English DT Note C1 INRAD INC,FED RES PROGRAM,NORTHVALE,NJ 07647. INRAD INC,FED DEV PROGRAM,NORTHVALE,NJ 07647. RP BARNES, NP (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 2 TC 2 Z9 2 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 APR PY 1995 VL 31 IS 4 BP 142 EP 143 PG 2 WC Optics SC Optics GA QT088 UT WOS:A1995QT08800027 ER PT J AU GITIS, NV DELLACORTE, C ETSION, I FLEISCHAUER, PD GAO, C KANEKO, R RICE, SL STREATOR, JL TING, LL AF GITIS, NV DELLACORTE, C ETSION, I FLEISCHAUER, PD GAO, C KANEKO, R RICE, SL STREATOR, JL TING, LL TI NATURE OF FRICTION COEFFICIENT - PANEL DISCUSSION SO LUBRICATION ENGINEERING LA English DT Discussion RP GITIS, NV (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Etsion, Izhak/B-1043-2008 NR 0 TC 0 Z9 0 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 1995 VL 51 IS 4 BP 336 EP 338 PG 3 WC Engineering, Mechanical SC Engineering GA QR868 UT WOS:A1995QR86800011 ER PT J AU COY, JJ AF COY, JJ TI A CELEBRATION OF THE 80-YEARS MILESTONE SO MECHANISM AND MACHINE THEORY LA English DT Item About an Individual RP COY, JJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0094-114X J9 MECH MACH THEORY JI Mech. Mach. Theory PD APR PY 1995 VL 30 IS 3 BP 491 EP 492 DI 10.1016/0094-114X(95)90000-D PG 2 WC Engineering, Mechanical SC Engineering GA QG611 UT WOS:A1995QG61100013 ER PT J AU BAGLEY, RL JONES, DIG FREED, AD AF BAGLEY, RL JONES, DIG FREED, AD TI RENEWAL CREEP THEORY SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID DEFORMATION AB The mathematics of probability are used to construct a framework that describes some key features of primary and secondary creep. The underlying assumption is that dislocation slip and annihilation are probabilistic events. The resulting mathematical framework takes the form of renewal theory from probability theory. Renewal creep theory provides a mathematical framework for primary creep that accommodates previously developed empirical descriptions. Renewal creep theory also predicts the existence of secondary creep as an asymptotically constant strain-rate phenomenon. Creep modeling techniques are demonstrated for three titanium alloys. C1 TECHNOL SCI SERV INC, DAYTON, OH 45431 USA. NASA, LEWIS RES CTR, DIV MAT, CLEVELAND, OH 44135 USA. RP BAGLEY, RL (reprint author), USAF, WRIGHT LAB, FLIGHT DYNAM DIRECTORATE, DIV STRUCT, WRIGHT PATTERSON AFB, OH 45433 USA. OI Freed, Alan/0000-0002-3492-0628 NR 25 TC 4 Z9 4 U1 0 U2 1 PU SPRINGER PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 USA SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD APR PY 1995 VL 26 IS 4 BP 829 EP 843 DI 10.1007/BF02649080 PG 15 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA QJ932 UT WOS:A1995QJ93200007 ER PT J AU WANG, L XU, K BOWMAN, RR ARSENAULT, RJ AF WANG, L XU, K BOWMAN, RR ARSENAULT, RJ TI INTERFACES IN CONTINUOUS FILAMENT-REINFORCED AL2O3/NIAL COMPOSITES SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID FOIL THICKNESS AB Interfacial structures in a continuous Al2O3 filament-reinforced NiAl composite were investigated by transmission electron microscopy (TEM). A graphite phase, which is an artifact of the composite fabrication procedure, decorates the interfacial region of the composite. The presence of the graphite is believed to play a role in both the low interfacial bond strength in the as-fabricated composite and the further reduction in bond strength after 10 thermal cycles in the temperature range of 373 to 1373 K. In regions where the graphite phase was not present, there appeared to be an intimate bond between the NiAl matrix and the Al2O3 filaments. Simulation of TEM diffraction contrast images based upon a three-dimensional (3D) finite element analysis was employed to investigate the nature of the residual strains in regions along the interface. The simulations suggested that radial residual strains within the Al2O3 filaments were randomly distributed along the interface. These strains are believed to be related to dislocation nucleation in the NiAl, which results from the relaxation of the thermally generated residual stresses. C1 UNIV MARYLAND,DEPT MAT & NUCL ENGN,COLLEGE PK,MD 20742. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 13 TC 6 Z9 6 U1 0 U2 0 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD APR PY 1995 VL 26 IS 4 BP 897 EP 903 DI 10.1007/BF02649086 PG 7 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA QJ932 UT WOS:A1995QJ93200013 ER PT J AU WATSON, MG ROSEN, SR ODONOGHUE, D BUCKLEY, DAH WARNER, B HELLIER, C RAMSEYER, T DONE, C MADEJSKI, G AF WATSON, MG ROSEN, SR ODONOGHUE, D BUCKLEY, DAH WARNER, B HELLIER, C RAMSEYER, T DONE, C MADEJSKI, G TI OPTICAL-PROPERTIES OF THE NEW POLAR RXJ1940.2-1025 SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE BINARIES, CLOSE; STARS, INDIVIDUAL, RXJ1940.2-1025; X-RAYS, STARS ID ABSORPTION DIPS; AM; ACCRETION; SYSTEM; VARIABILITY; DISCOVERY; NGC-6814; GEOMETRY AB We present detailed optical spectroscopic and photometric observations of the recently discovered X-ray source, RXJ1940.2 - 1025. This object, whose periodic X-ray emission had previously been confused with the X-ray signal from the nearby active galaxy, NGC 6814, is almost certainly an AM Her binary. Its 3.4-h orbital light curve is strongly modulated, and possesses a prominent dip feature lasting about 850 s. The dip ingress and egress are well resolved (lasting about 200 s each) at optical wavelengths. Blueward of 5500 Angstrom the profile is flat-bottomed and near total. In contrast, we find that a reduced but significant residual flux is present in the Balmer and He II emission lines throughout the dip. The line fluxes, however, recover much more slowly than the continuum at the end of the dip. At wavelengths beyond 5500 Angstrom, the clear signature of an M4 dwarf secondary star becomes visible during dip minimum, yielding an estimate of 230 pc for the distance to RXJ1940.2 - 1025. Using our broad-band photometry, we demonstrate that the dip feature recurs with a period of 12 116.2 +/- 0.4 s. The accuracy with which we can determine this period is sufficient to extrapolate back to the epoch of the ROSAT PSPC observations. We can thus demonstrate that the optical dip occurs in the middle of the X-ray 'low state', and is not associated with the prominent broader minimum evident in the soft X-ray light curves. We find, however, that there is evidence for an X-ray dip feature corresponding to the optical dip both in the ROSAT data, and in earlier Ginga hard X-ray data. Under the assumption that the X-ray and optical dips are the same phenomenon, we derive a refined ephemeris for the dips, yielding a dip period of 12 116.30 +/- 0.01 s. Whilst, on balance, the X-ray and optical properties of the dip suggest absorption in the accretion now rather than an eclipse by the companion star as the cause, the inferred wavelength dependence of the optical opacity of the absorber does not follow that expected for free-free absorption in a homogeneous absorber. This may be circumvented by invoking an inhomogeneous accretion now. C1 UNIV CAPE TOWN,DEPT ASTRON,RONDEBOSCH 7700,SOUTH AFRICA. S AFRICAN ASTRON OBSERV,CAPE TOWN 7935,SOUTH AFRICA. UNIV TEXAS,MCDONALD OBSERV,AUSTIN,TX 78712. UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP WATSON, MG (reprint author), UNIV LEICESTER,DEPT PHYS & ASTRON,UNIV RD,LEICESTER LE1 7RH,LEICS,ENGLAND. RI done, chris/D-4605-2016 OI done, chris/0000-0002-1065-7239 NR 24 TC 35 Z9 35 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 APR 1 PY 1995 VL 273 IS 3 BP 681 EP 698 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QP724 UT WOS:A1995QP72400021 ER PT J AU DEE, DP AF DEE, DP TI ONLINE ESTIMATION OF ERROR COVARIANCE PARAMETERS FOR ATMOSPHERIC DATA ASSIMILATION SO MONTHLY WEATHER REVIEW LA English DT Article ID METEOROLOGICAL OBSERVATIONS; KALMAN FILTER; INTERPOLATION; SYSTEM; EQUATIONS; MATRICES AB A simple scheme is presented for on-line estimation of covariance parameters in statistical data assimilation systems. The scheme is based on a maximum-likelihood approach in which estimates are produced on the basis of a single batch of simultaneous observations. Single-sample covariance estimation is reasonable as long as the number of available observations exceeds the number of tunable parameters by two or three orders of magnitude. Not much is known at present about model error associated with actual forecast systems. Our scheme can be used to estimate some important statistical model error parameters such as regionally averaged variances or characteristic correlation length scales. The advantage of the single-sample approach is that it does not rely on any assumptions about the temporal behavior of the covariance parameters: time-dependent parameter estimates can be continuously adjusted on the basis of current observations. This is of practical importance since it is likely to be the case that both model error and observation error strongly depend on the actual state of the atmosphere. The single-sample estimation scheme can be incorporated into any four-dimensional statistical data assimilation system that involves explicit calculation of forecast error covariances, including optimal interpolation (OI) and the simplified Kalman filter (SKF). The computational cost of the scheme is high but not prohibitive: online estimation of one or two covariance parameters in each analysis box of an operational boxed-OI system is currently feasible. A number of numerical experiments performed with an adaptive SKF and an adaptive version of OI, using a linear two-dimensional shallow-water model and artificially generated model error are described. The performance of the nonadaptive versions of these methods turns out to depend rather strongly on the correct specification of model error parameters. These parameters are estimated under a variety of conditions, including uniformly distributed model error and time-dependent model error statistics. C1 NASA,GODDARD SPACE FLIGHT CTR,DATA ASSIMILAT OFF,GREENBELT,MD 20771. RP DEE, DP (reprint author), DELFT HYDRAUL,POB 152,8300 AD EMMELOORD,NETHERLANDS. NR 38 TC 223 Z9 229 U1 1 U2 15 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 1995 VL 123 IS 4 BP 1128 EP 1145 DI 10.1175/1520-0493(1995)123<1128:OLEOEC>2.0.CO;2 PG 18 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QP163 UT WOS:A1995QP16300010 ER PT J AU PATI, V SHAHSHAHANI, M SITARAM, A AF PATI, V SHAHSHAHANI, M SITARAM, A TI THE SPHERICAL MEAN-VALUE OPERATOR FOR COMPACT SYMMETRICAL SPACES SO PACIFIC JOURNAL OF MATHEMATICS LA English DT Article ID POMPEIU PROBLEM AB When M is a compact symmetric space, the spherical mean value operator L(r) (for a fixed r > 0) acting on L(2)(M) is considered. The eigenvalues lambda for L(r)f = lambda f are explicitly determined in terms of the elementary spherical functions associated with the symmetric space. Alternative proofs are also provided for some results of T. Sunada regarding the special eigenvalues +1 and -1 using a purely harmonic analytic point of view. C1 JET PROPULS LAB,PASADENA,CA 91110. RP PATI, V (reprint author), INDIAN STAT INST,BANGALORE 560059,KARNATAKA,INDIA. NR 9 TC 1 Z9 1 U1 0 U2 0 PU PACIFIC JOURNAL MATHEMATICS PI BERKELEY PA PO BOX 4163, BERKELEY, CA 94704-0163 SN 0030-8730 J9 PAC J MATH JI Pac. J. Math. PD APR PY 1995 VL 168 IS 2 BP 335 EP 344 PG 10 WC Mathematics SC Mathematics GA RM019 UT WOS:A1995RM01900007 ER PT J AU PEDDLE, DR AF PEDDLE, DR TI KNOWLEDGE FORMULATION FOR SUPERVISED EVIDENTIAL CLASSIFICATION SO PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING LA English DT Article ID EXPERT SYSTEM; INTEGRATION AB The Dempster-Shafer Theory of Evidence provides an appropriate framework for overcoming problems associated with the analysis, integration, and classification of modern, multisource data sets. However, current methods for generating the prerequisite evidence are subjective and inconsistent. To address this, a more objective approach is presented for deriving evidence from histogram bin transformations of supervised training data frequency distributions. The procedure is illustrated by an example application in which evidential land-cover classification accuracy is increased from a kappa coefficient of 0.51 to 0.90 by appropriate use of bin transformation functions for a complex, mountainous environment in the Canadian sub-Arctic. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD. RP PEDDLE, DR (reprint author), UNIV WATERLOO,INST SPACE & TERR SCI,DEPT GEOG,EARTH OBSERVAT LAB,WATERLOO,ON N2L 3G1,CANADA. NR 20 TC 34 Z9 38 U1 0 U2 0 PU AMER SOC PHOTOGRAMMETRY PI BETHESDA PA 5410 GROSVENOR LANE SUITE 210, BETHESDA, MD 20814-2160 SN 0099-1112 J9 PHOTOGRAMM ENG REM S JI Photogramm. Eng. Remote Sens. PD APR PY 1995 VL 61 IS 4 BP 409 EP 417 PG 9 WC Geography, Physical; Geosciences, Multidisciplinary; Remote Sensing; Imaging Science & Photographic Technology SC Physical Geography; Geology; Remote Sensing; Imaging Science & Photographic Technology GA QQ497 UT WOS:A1995QQ49700005 ER PT J AU DRACHMAN, RJ BHATIA, AK AF DRACHMAN, RJ BHATIA, AK TI RYDBERG LEVELS OF LITHIUM SO PHYSICAL REVIEW A LA English DT Article ID STATES; VALUES; HELIUM RP NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. NR 17 TC 39 Z9 39 U1 1 U2 7 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 2469-9926 EI 2469-9934 J9 PHYS REV A JI Phys. Rev. A PD APR PY 1995 VL 51 IS 4 BP 2926 EP 2930 DI 10.1103/PhysRevA.51.2926 PG 5 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA QT401 UT WOS:A1995QT40100038 ER PT J AU SEIDEL, DJ MALEKI, L AF SEIDEL, DJ MALEKI, L TI EFFICIENT QUENCHING OF POPULATION TRAPPING IN EXCITED YB+ SO PHYSICAL REVIEW A LA English DT Note ID YTTERBIUM IONS; LASER; IRRADIATION; LIGHT RP SEIDEL, DJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 24 TC 13 Z9 13 U1 0 U2 3 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD APR PY 1995 VL 51 IS 4 BP R2699 EP R2702 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA QT401 UT WOS:A1995QT40100011 ER PT J AU MORAN, TG AF MORAN, TG TI SPECTROSCOPIC STUDY OF MOLECULAR-HYDROGEN PROCESSES IN A MIRROR-CONFINED PLASMA SO PHYSICAL REVIEW E LA English DT Article ID H-2; ELECTRONS; ATOMS; IONS; D2 C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20770. RP MORAN, TG (reprint author), APPL RES CORP,8201 CORP DR,LANDOVER,MD 20783, USA. NR 29 TC 1 Z9 1 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1063-651X J9 PHYS REV E JI Phys. Rev. E PD APR PY 1995 VL 51 IS 4 BP 3464 EP 3474 DI 10.1103/PhysRevE.51.3464 PN B PG 11 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA QV541 UT WOS:A1995QV54100006 ER PT J AU COSTINER, S TAASAN, S AF COSTINER, S TAASAN, S TI ADAPTIVE MULTIGRID TECHNIQUES FOR LARGE-SCALE EIGENVALUE PROBLEMS - SOLUTIONS OF THE SCHRODINGER-PROBLEM IN 2 AND 3 DIMENSIONS SO PHYSICAL REVIEW E LA English DT Article ID MULTILEVEL C1 NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681. RP COSTINER, S (reprint author), WEIZMANN INST SCI,DEPT APPL MATH & COMP SCI,IL-76100 REHOVOT,ISRAEL. NR 27 TC 27 Z9 27 U1 0 U2 3 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1063-651X J9 PHYS REV E JI Phys. Rev. E PD APR PY 1995 VL 51 IS 4 BP 3704 EP 3717 DI 10.1103/PhysRevE.51.3704 PN B PG 14 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA QV541 UT WOS:A1995QV54100030 ER PT J AU ZHOU, Y AF ZHOU, Y TI CLASSICAL CLOSURE THEORY AND LAM INTERPRETATION OF EPSILON-RENORMALIZATION GROUP THEORY SO PHYSICAL REVIEW E LA English DT Note ID ISOTROPIC TURBULENCE; SIMULATION RP ZHOU, Y (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681, USA. NR 12 TC 1 Z9 1 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1063-651X J9 PHYS REV E JI Phys. Rev. E PD APR PY 1995 VL 51 IS 4 BP 3745 EP 3747 DI 10.1103/PhysRevE.51.3745 PN B PG 3 WC Physics, Fluids & Plasmas; Physics, Mathematical SC Physics GA QV541 UT WOS:A1995QV54100037 ER PT J AU SMITH, SD GOULD, RW ZAUGG, WS HARRELL, LW MAHNKEN, VW AF SMITH, SD GOULD, RW ZAUGG, WS HARRELL, LW MAHNKEN, VW TI PRERELEASE DISEASE TREATMENT WITH POTASSIUM-PERMANGANATE FOR FALL CHINOOK SALMON SMOLTS SO PROGRESSIVE FISH-CULTURIST LA English DT Article AB Standard potassium permanganate treatment (2 mg KMnO4/L freshwater for 1 h on three consecutive days) was applied to presmolts (parr) and smolts of fall chinook salmon (Oncorhynchus tshawytscha). Smoltification was determined by gill Na+, K+-ATPase activity. Treatments were conducted 73, 59, 45, 31, 16, and 2 d prior to full-strength seawater entry in aquaria. Potassium permanganate did not affect either growth or survival in seawater over 25 d. We observed a delayed rise in gill Na+,K+-ATPase activity in fish treated 16 d prior to seawater entry. C1 US FISH & WILDLIFE SERV,ANCHORAGE,AK 99503. NATL MARINE FISHERIES SERV,NW & ALASKA FISHERY SCI CTR,MANCHESTER FIELD STN,MANCHESTER,WA 98353. RP SMITH, SD (reprint author), NATL BIOL SERV,NW BIOL SCI CTR SEATTLE,COLUMBIA RIVER RES LAB,55014 COOK UNDERWOOD RD,COOK,WA 98605, USA. NR 10 TC 1 Z9 1 U1 0 U2 0 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 SN 0033-0779 J9 PROG FISH CULT JI Progress. Fish-Cult. PD APR PY 1995 VL 57 IS 2 BP 102 EP 106 DI 10.1577/1548-8640(1995)057<0102:PDTWPP>2.3.CO;2 PG 5 WC Fisheries SC Fisheries GA QR334 UT WOS:A1995QR33400002 ER PT J AU MALBET, F YU, JW SHAO, M AF MALBET, F YU, JW SHAO, M TI HIGH-DYNAMIC-RANGE IMAGING USING A DEFORMABLE MIRROR FOR SPACE CORONOGRAPHY SO PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC LA English DT Article ID QUASARS AB The need for high-dynamic-range imaging is crucial in many astronomical fields, such as extra-solar planet direct detection, extragalactic science, and circumstellar imaging. Using a high-quality coronograph, dynamic ranges of up to 10(5) have been achieved. However the ultimate limitations of coronographs do not come from their optical performances, but from scattering due to imperfections in the optical surfaces of the collecting system. We propose the use of a deformable mirror to correct these imperfections and decrease the scattering level in local regions called ''dark holes.'' Using this technique will enable imaging of fields with dynamic ranges exceeding 10(8). We show that the dark-hole algorithm results in a lower scattering level than simply minimizing the rms figure error (maximum-strehl-ratio algorithm). The achievable scattering level inside the dark-hole region will depend on the number of mirror actuators, the surface quality of the telescope, the single-actuator influence function, and the observing wavelength. We have simulated cases with a 37X37 deformable mirror using data from the Hubble Space Telescope optics without spherical aberrations and have demonstrated dark holes with rectangular and annular shapes. We also present a preliminary concept of a monolithic, fully integrated, high-density deformable mirror which can be used for this type of space application. C1 CALTECH,JET PROPULS LAB,PASADENA,CA 91109. NR 13 TC 140 Z9 140 U1 1 U2 7 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 APR PY 1995 VL 107 IS 710 BP 386 EP 398 DI 10.1086/133563 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QT979 UT WOS:A1995QT97900008 ER PT J AU SCULLY, JP AF SCULLY, JP TI PEOPLE - THE IMPERFECT COMMUNICATORS SO QUALITY PROGRESS LA English DT Article RP SCULLY, JP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. NR 0 TC 2 Z9 2 U1 0 U2 0 PU AMER SOC QUALITY CONTROL-ASQC PI MILWAUKEE PA ASQC MEMBERSHIP MANAGER 611 E. WISCONSIN AVENUE, MILWAUKEE, WI 53202 SN 0033-524X J9 QUAL PROG JI Qual. Prog. PD APR PY 1995 VL 28 IS 4 BP 37 EP 39 PG 3 WC Engineering, Multidisciplinary; Engineering, Industrial; Management; Operations Research & Management Science SC Engineering; Business & Economics; Operations Research & Management Science GA QQ936 UT WOS:A1995QQ93600023 ER PT J AU HARRIES, JE RUSSELL, JM PARK, J TUCK, AF DRAYSON, SR AF HARRIES, JE RUSSELL, JM PARK, J TUCK, AF DRAYSON, SR TI OBSERVATIONS OF ABSORBING LAYERS IN THE ANTARCTIC STRATOSPHERE IN OCTOBER 1991 SO QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY LA English DT Article ID LIDAR OBSERVATIONS; AEROSOL; CLOUDS AB Measurements of the transmission of solar infrared radiation through the earth's atmosphere, by the HALOE experiment on the UARS spacecraft, were made at high southern latitudes during October 1991. These observations are direct measurements of atmospheric transmission, and do not need to be passed through a composition or temperature retrieval process; they are, therefore, amenable to direct interpretation. During October 1991 the profiles of transmittance versus height in the atmosphere show clear evidence for the arrival (from more northerly latitudes) of layers of some material which absorbs infrared radiation, at heights of up to 28 km. The spatial structure of the absorbing material shows considerable variability with longitude at a given latitude. The spectral properties of the detected absorption, measured at the various HALOE wavelengths, are consistent with absorption by sulphate aerosol, and clearly implicate the volcanic eruptions from Mts Pinatubo and Hudson during 1991. These results provide direct and detailed evidence for the arrival of layers of what appears to be sulphate aerosol during the 1991 southern spring, at latitudes as high as 80 degrees south. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. UNIV MICHIGAN,ANN ARBOR,MI 48109. RP HARRIES, JE (reprint author), UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,EXHIBIT RD,LONDON SW7 2BX,ENGLAND. RI Tuck, Adrian/F-6024-2011 OI Tuck, Adrian/0000-0002-2074-0538 NR 15 TC 3 Z9 3 U1 0 U2 1 PU ROYAL METEOROLOGICAL SOC PI READING PA 104 OXFORD ROAD, READING, BERKS, ENGLAND RG1 7LJ SN 0035-9009 J9 Q J ROY METEOR SOC JI Q. J. R. Meteorol. Soc. PD APR PY 1995 VL 121 IS 523 BP 655 EP 667 DI 10.1002/qj.49712152310 PN A PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QZ800 UT WOS:A1995QZ80000009 ER PT J AU KALIL, C AF KALIL, C TI AFTER 34,000 ORBITS OF EARTH, POLYMERS ANALYZED BY SPM SO R&D MAGAZINE LA English DT Article RP KALIL, C (reprint author), NASA,LANGLEY RES CTR,ANALYT SERV & MAT,HAMPTON,VA 23665, 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 0746-9179 J9 R&D MAG JI R D Mag. PD APR PY 1995 VL 37 IS 5 BP 68 EP 69 PG 2 WC Engineering, Industrial; Multidisciplinary Sciences SC Engineering; Science & Technology - Other Topics GA QT885 UT WOS:A1995QT88500009 ER PT J AU BADHWAR, GD PATEL, JU CUCINOTTA, FA WILSON, JW AF BADHWAR, GD PATEL, JU CUCINOTTA, FA WILSON, JW TI MEASUREMENTS OF THE SECONDARY PARTICLE ENERGY-SPECTRA IN THE SPACE-SHUTTLE SO RADIATION MEASUREMENTS LA English DT Article ID CROSS-SECTIONS; MEV PROTONS; NUCLEI AB Measurements of the energy spectra of secondary particles produced by galactic cosmic rays and trapped protons due to the nuclear interactions of these particles with the Shuttle shielding provide a powerful tool for validating radiation transport codes. A code validated in this way can be used to better estimate the dose and dose equivalent to body organs, measurements that cannot be made directly. The principal cause of single event upsets in electronic devices in the region of the South Atlantic Anomaly is secondary particles, and even in the region of galactic cosmic radiation a significant fraction is produced by secondary particles. In this paper, we describe the first direct measurements of the energy spectra of secondary protons, deuterons, tritons, 3He and 4He produced by galactic cosmic rays inside the Space Shuttle using a charged particle spectrometer. A comparison of these spectra with radiation transport code HZETRN showed reasonably good agreement for secondary protons. However, the code seriously underestimated the flux of all other light ions. The code has been modified to include pick-up and knock-on processes. The modified code leads to good agreement for deuterons and 3He but not for other light ions. This revised code leads to about 10% higher dose equivalent than the original code under moderate shielding, if we assume that higher charge ion fluxes are correctly predicted by the model. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP BADHWAR, GD (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 21 TC 21 Z9 23 U1 0 U2 1 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 1350-4487 J9 RADIAT MEAS JI Radiat. Meas. PD APR PY 1995 VL 24 IS 2 BP 129 EP 138 DI 10.1016/1350-4487(94)00094-H PG 10 WC Nuclear Science & Technology SC Nuclear Science & Technology GA QW876 UT WOS:A1995QW87600004 PM 11539881 ER PT J AU MARSHAK, A DAVIS, A WISCOMBE, W TITOV, G AF MARSHAK, A DAVIS, A WISCOMBE, W TITOV, G TI THE VERISIMILITUDE OF THE INDEPENDENT PIXEL APPROXIMATION USED IN-CLOUD REMOTE-SENSING SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID RADIATIVE-TRANSFER; SCATTERING AB We assess the validity of the ''independent pixel approximation'' (IPA) using Monte Carlo simulations of realistic scale-invariant clouds modeled with 2-D horizontal variations in optical depth. The IPA uses a plane-parallel approximation for each pixel, and is used in virtually all cloud remote sensing algorithms. We confirm the validity of the IPA at the largest scales and demonstrate its shortcomings on the smallest scales: a) It overestimates the variability of the radiation field when the optical depth field is known, and b) it underestimates the variability of the optical depth field when the radiation field is known. Both effects are due to smoothing by horizontal fluxes. C1 RUSSIAN ACAD SCI,INST ATMOSPHER OPT,TOMSK,RUSSIA. SCI SYST & APPLICAT INC,LANHAM,MD. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES,GREENBELT,MD 20771. RP MARSHAK, A (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CLIMAT & RADIAT BRANCH,CODE 913,GREENBELT,MD 20771, USA. RI Wiscombe, Warren/D-4665-2012; Marshak, Alexander/D-5671-2012 OI Wiscombe, Warren/0000-0001-6844-9849; NR 24 TC 54 Z9 57 U1 0 U2 1 PU ELSEVIER SCIENCE PUBL CO 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 1995 VL 52 IS 1 BP 71 EP 78 DI 10.1016/0034-4257(95)00016-T PG 8 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA RE087 UT WOS:A1995RE08700006 ER PT J AU ELDRIDGE, JI AF ELDRIDGE, JI TI ENVIRONMENTAL-EFFECTS ON FIBER DEBONDING AND SLIDING IN AN SCS-6 SIC FIBER-REINFORCED REACTION-BONDED SI3N4 COMPOSITE SO SCRIPTA METALLURGICA ET MATERIALIA LA English DT Article ID MATRIX RP ELDRIDGE, JI (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 10 TC 3 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0956-716X J9 SCRIPTA METALL MATER JI Scr. Metall. Materialia PD APR 1 PY 1995 VL 32 IS 7 BP 1085 EP 1089 DI 10.1016/0956-716X(94)00008-6 PG 5 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA QL456 UT WOS:A1995QL45600026 ER PT J AU YAN, J SARUKKAI, S MEHRA, P AF YAN, J SARUKKAI, S MEHRA, P TI PERFORMANCE-MEASUREMENT, VISUALIZATION AND MODELING OF PARALLEL AND DISTRIBUTED PROGRAMS USING THE AIMS TOOLKIT SO SOFTWARE-PRACTICE & EXPERIENCE LA English DT Article DE PARALLEL AND DISTRIBUTED PROGRAMMING; PERFORMANCE EVALUATION; VISUALIZATION TOOLS; MODELING AND PREDICTION; MESSAGE-PASSING PROGRAMS AB Writing large-scale parallel and distributed scientific applications that make optimum use of the multiprocessor is a challenging problem. Typically, computational resources are underused due to performance failures in the application being executed. Performance-tuning tools are essential for exposing these performance failures and for suggesting ways to improve program performance. In this paper, we first address fundamental issues in building useful performance-tuning tools and then describe our experience with the AIMS toolkit for tuning parallel and distributed programs on a variety of platforms. AIMS supports source-code instrumentation, run-time monitoring, graphical execution profiles, performance indices and automated modeling techniques as ways to expose performance problems of programs. Using several examples representing a broad range of scientific applications, we illustrate AIMS' effectiveness in exposing performance problems in parallel and distributed programs. RP YAN, J (reprint author), NASA,AMES RES CTR,RECOM TECHNOL,MS T27A-1,MOFFETT FIELD,CA 94035, USA. NR 22 TC 54 Z9 54 U1 0 U2 0 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 0038-0644 J9 SOFTWARE PRACT EXPER JI Softw.-Pract. Exp. PD APR PY 1995 VL 25 IS 4 BP 429 EP 461 DI 10.1002/spe.4380250406 PG 33 WC Computer Science, Software Engineering SC Computer Science GA QU730 UT WOS:A1995QU73000005 ER PT J AU HAGYARD, MJ KINEKE, JI AF HAGYARD, MJ KINEKE, JI TI IMPROVED METHOD FOR CALIBRATING FILTER VECTOR MAGNETOGRAPHS SO SOLAR PHYSICS LA English DT Article ID STOKES PROFILE ANALYSIS; MAGNETIC-FIELDS; SUNSPOTS AB We have developed a method to improve present techniques for calibrating linear and circular polarization signals in terms of the vector magnetic field from observations with a filter vector magnetograph. The method substantially reduces inaccuracies in deriving the inclination of the field from theoretical calibrations for inclination angles in the range 30 degrees-60 degrees. We outline the method and demonstrate its improved accuracy in applications to a model magnetic field and to actual magnetograph observations. We also demonstrate how the method affects the calculation of derived parameters using the example of the vertical electric current density. C1 CTR COLL,DEPT MATH & SCI,DANVILLE,KY 40422. RP HAGYARD, MJ (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES82,HUNTSVILLE,AL 35812, USA. NR 10 TC 10 Z9 10 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 1995 VL 158 IS 1 BP 11 EP 28 DI 10.1007/BF00680832 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RB343 UT WOS:A1995RB34300002 ER PT J AU WILSON, RM AF WILSON, RM TI ON THE USE OF FIRST SPOTLESS DAY AS A PREDICTOR FOR SUNSPOT MINIMUM SO SOLAR PHYSICS LA English DT Article ID CYCLE AB Defining the 'first spotless day' of a sunspot cycle as the first day Without spots relative to sunspot maximum during the decline of the solar cycle, one finds that the timing of that occurrence can be used as a predictor for the occurrence of solar minimum of the following cycle. For cycle 22, the first spotless day occurred in April 1994, based on the International sunspot number index, although other indices (Boulder and American) indicated the first spotless day to have occurred earlier (September 1993). For cycles 9-14, sunspot minimum followed the first spotless day by about 72 months, having a range of 62-82 months; for cycles 15-21, sunspot minimum followed the first spotless day by about 35 months, having a range of 27-40 months. Similarly, the timing of first spotless day relative to sunspot minimum and maximum for the same cycle reveals that it followed minimum(maximum) by about 69 (18) months during cycles 9-14 and by about 90 (44) months during cycles 15-21. Accepting April 1994 as the month of first spotless day occurrence for cycle 22, one finds that it occurred 91 months into the cycle and 57 months following sunspot maximum. Such values indicate that its behavior more closely matches that found for cycles 15-21 rather than for cycles 9-14. Therefore, one infers that sunspot minimum for cycle 23 will occur in about 2-3 years, or about April 1996 to April 1997. Accepting the earlier date of first spotless day occurrence indicates that sunspot minimum for cycle 23 could come several months earlier, perhaps late 1995. RP WILSON, RM (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812, USA. NR 8 TC 10 Z9 10 U1 2 U2 4 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 1995 VL 158 IS 1 BP 197 EP 204 DI 10.1007/BF00680842 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA RB343 UT WOS:A1995RB34300012 ER PT J AU KOHL, JL GARDNER, LD STRACHAN, L FISHER, R GUHATHAKURTA, M AF KOHL, JL GARDNER, LD STRACHAN, L FISHER, R GUHATHAKURTA, M TI SPARTAN-201 CORONAL SPECTROSCOPY DURING THE POLAR PASSES OF ULYSSES SO SPACE SCIENCE REVIEWS LA English DT Review DE SOLAR WIND; UV SPECTROSCOPY ID SOLAR-WIND; IONS; ACCELERATION; TEMPERATURE AB Spartan 201 is a shuttle deployed spacecraft that is scheduled to perform ultraviolet spectroscopy and white light polarimetry of the extended solar corona during two 40 hour missions to occur in September 1994 and August 1995. The spectroscopy is done with an ultraviolet coronal spectrometer which measures the intensity and spectral line profile of HI Ly alpha up to heliocentric heights of 3.5 solar radii. It also measures the intensities of the OVI doublet at 1032 and 1037 Angstrom and of Fe XII at 1242 Angstrom. The HI Ly alpha line profile measurements are used to determine the random velocity distribution of coronal protons along the line-of-sight. The absolute HI Ly alpha intensities can be used together with electron densities from the white light coronagraph to estimate electron temperatures from hydrogen ionization balance calculations, and bulk outflow velocities from models of Doppler dimmed resonant scattering. Intensities of minor ion lines are used to determine coronal abundances and outflow velocities of O5+. Ultraviolet spectroscopy of extended coronal regions from the 11 April 1993 mission of Spartan 201 are discussed. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP HARVARD SMITHSONIAN CTR ASTROPHYS, CAMBRIDGE, MA 02138 USA. NR 15 TC 28 Z9 28 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 29 EP 38 DI 10.1007/BF00768750 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300006 ER PT J AU DOMINGO, V FLECK, B POLAND, AI AF DOMINGO, V FLECK, B POLAND, AI TI SOHO - THE SOLAR AND HELIOSPHERIC OBSERVATORY SO SPACE SCIENCE REVIEWS LA English DT Review DE SOLAR PHYSICS; SOLAR INTERIOR; SOLAR CORONA; SOLAR WIND; SOHO AB The Solar and Heliospheric Observatory (SOHO), together with the Cluster mission, constitutes ESA's Solar Terrestrial Science Programme (STSP), the first ''Cornerstone'' of the Agency's long-term programme ''Space Science - Horizon 2000''. STSP, which is being developed in a strong collaborative effort with NASA, will allow comprehensive studies to be made of the both the Sun's interior and its outer atmosphere, the acceleration and propagation of the solar wind and its interaction with the Earth. This paper gives a brief overview of one part of STSP, the SOHO mission. C1 NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RP EUROPEAN SPACE TECHNOL CTR, EUROPEAN SPACE AGCY, DEPT SPACE SCI, 2200 AG NOORDWIJK, NETHERLANDS. RI Fleck, Bernhard/C-9520-2012 NR 2 TC 50 Z9 54 U1 1 U2 4 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 81 EP 84 DI 10.1007/BF00768758 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300014 ER PT J AU MCCOMAS, DJ PHILLIPS, JL BAME, SJ GOSLING, JT GOLDSTEIN, BE NEUGEBAUER, M AF MCCOMAS, DJ PHILLIPS, JL BAME, SJ GOSLING, JT GOLDSTEIN, BE NEUGEBAUER, M TI ULYSSES SOLAR-WIND OBSERVATIONS TO 56-DEGREES SOUTH SO SPACE SCIENCE REVIEWS LA English DT Review AB In the 25 months since Jupiter flyby, the Ulysses spacecraft has climbed southward to a heliolatitude of 56 degrees. This transit has been marked by an evolution from slow, dense coronal streamer belt solar wind through two regions where the rotation of the Sun carried Ulysses back and forth between streamer belt and polar coronal hole flows, and finally into a region of essentially continuous fast, low density solar wind from the southern polar coronal hole. Throughout these large changes, the momentum flux normalized to 1 AU displays very little systematic variation. In addition, the bulk properties of the polar coronal hole solar wind are quite similar to those observed in high speed streams in the ecliptic plane at 1 AU. Coronal mass ejections and forward and reverse shocks associated with corotating interaction regions have also been observed at higher heliolatitudes, however they are seen less frequently with increasing southern heliolatitude. Ulysses has thus far collected data from 20 degrees of nearly contiguous solar wind flows from the polar coronal hole. We examine these data for characteristic variations with heliolatitude and find that the bulk properties in general show very little systematic variation across the southern polar coronal hole so far. C1 JET PROPULS LAB, PASADENA, CA USA. RP LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87544 USA. NR 7 TC 33 Z9 33 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 93 EP 98 DI 10.1007/BF00768760 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300016 ER PT J AU GOSLING, JT BAME, SJ MCCOMAS, DJ PHILLIPS, JL PIZZO, VJ GOLDSTEIN, BE NEUGEBAUER, M AF GOSLING, JT BAME, SJ MCCOMAS, DJ PHILLIPS, JL PIZZO, VJ GOLDSTEIN, BE NEUGEBAUER, M TI SOLAR-WIND COROTATING STREAM INTERACTION REGIONS OUT OF THE ECLIPTIC-PLANE - ULYSSES SO SPACE SCIENCE REVIEWS LA English DT Review ID PIONEER-10 AB Ulysses plasma observations reveal that the forward shocks that commonly bound the leading edges of corotating interaction regions (CIRs) beyond similar to 2 AU from the Sun at low heliographic latitudes nearly disappeared at a latitude of S26 degrees. On the other hand, the reverse shocks that commonly bound the trailing edges of the CIRs were observed regularly up to S41.5 degrees, but became weaker with increasing latitude. Only three CIR shocks have been observed poleward of S41.5 degrees; all of these were weak reverse shocks. The above effects are a result of the forward waves propagating to lower heliographic latitudes and the reverse waves to higher latitudes with increasing heliocentric distance. These observational results are in excellent agreement with the predictions of a global model of solar wind flows that originate in a simple tilted-dipole geometry back at the Sun. C1 SAN JUAN INST, SAN JUAN CAPISTRANO, CA USA. JET PROPULS LAB, PASADENA, CA USA. RP LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87544 USA. NR 10 TC 44 Z9 44 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 99 EP 104 DI 10.1007/BF00768761 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300017 ER PT J AU GOLDSTEIN, BE NEUGEBAUER, M GOSLING, JT BAME, SJ PHILLIPS, JL MCCOMAS, DJ BALOGH, A AF GOLDSTEIN, BE NEUGEBAUER, M GOSLING, JT BAME, SJ PHILLIPS, JL MCCOMAS, DJ BALOGH, A TI ULYSSES OBSERVATIONS OF SOLAR-WIND PLASMA PARAMETERS IN THE ECLIPTIC FROM 1.4-AU TO 5.4-AU AND OUT OF THE ECLIPTIC SO SPACE SCIENCE REVIEWS LA English DT Review AB We report observations of radial and latitudinal gradients of Ulysses plasma parameters. The solar wind velocity increased rapidly with latitude from 0 degrees to 35 degrees, then remained approximately constant at higher latitudes. Solar wind density decreased rapidly from 0 degrees to 35 degrees of latitude, and also was approximately constant beyond that latitude. The mass flux similarly decreased away from the equator (but less than the density), whereas the momentum flux was relatively constant. The radial gradient of the entropy at high latitude indicated a value for the polytrope index of about 1.72 (close to adiabatic); the in-ecliptic estimates of radial gradients for temperature and entropy may be biased by temporal variation. A striking increase in the alpha particle-proton velocity difference with latitude is found. C1 LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, LONDON, ENGLAND. RP CALTECH, JET PROPULS LAB, PASADENA, CA 91109 USA. NR 5 TC 8 Z9 8 U1 0 U2 2 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 113 EP 116 DI 10.1007/BF00768764 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300020 ER PT J AU GAZIS, PR BARNES, A MIHALOV, JD AF GAZIS, PR BARNES, A MIHALOV, JD TI PIONEER AND VOYAGER OBSERVATIONS OF LARGE-SCALE SPATIAL AND TEMPORAL VARIATIONS IN THE SOLAR-WIND SO SPACE SCIENCE REVIEWS LA English DT Review ID LATITUDE DEPENDENCE; LONGITUDE STRUCTURE; SPEED; STREAM AB The Pioneer 10, Pioneer 11, and Voyager 2 spacecraft were launched in 1972, 1974, and 1977, respectively. While these three spacecraft are all at comparatively low heliographic latitudes compared with Ulysses, their observations span almost two solar cycles, a range of heliocentric distances from 1 to 57 AU, and provide a unique insight into the long-term variability of the global structure of the solar wind. We examine the spatial and temporal variation of average solar wind parameters and fluxes. Our observations suggest that the global structure of the outer heliosphere during the declining phase of the solar cycle at heliographic latitudes up to 17.5 degrees N was characterized by two competing phenomena: 1) a large-scale increase of solar wind density, temperature, mass flux, dynamic pressure, kinetic energy flux, and thermal energy flux with heliographic latitude, similar to the large-scale latitudinal gradient of velocity seen in IPS observations, 2) a small-scale decrease in velocity and temperature, and increase in density near the heliospheric current sheet, which is associated with a band of low speed, low temperature, and high density solar wind similar to that observed in the inner heliosphere. C1 SAN JOSE STATE UNIV FDN, SAN JOSE, CA USA. RP NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 13 TC 2 Z9 2 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 117 EP 120 DI 10.1007/BF00768765 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300021 ER PT J AU MACDOWALL, RJ DESCH, MD KAISER, ML STONE, RG HESS, RA BALOGH, A BAME, SJ GOLDSTEIN, BE AF MACDOWALL, RJ DESCH, MD KAISER, ML STONE, RG HESS, RA BALOGH, A BAME, SJ GOLDSTEIN, BE TI THE 3-DIMENSIONAL EXTENT OF A HIGH-SPEED SOLAR-WIND STREAM SO SPACE SCIENCE REVIEWS LA English DT Review AB A primary goal of the Ulysses mission is to study the 3-dimensional structures making up the interplanetary medium, an example of which is the high speed solar wind stream observed in situ by Ulysses beginning in July 1992. In order to study the longitudinal extent of this stream as a function of Ulysses' increasing heliographic latitude, a second point of reference is required to separate spatial and temporal variations. Such a reference point is provided at Jupiter by a class of Jovian radio bursts, whose occurrence rate varies in a predictable way with solar wind speed. Using the in situ and remote observations from Ulysses, the extent of the high speed stream at similar to 5 AU is mapped and compared to the associated coronal hole boundary on the Sun. C1 HUGHES STX, LANHAM, MD 20706 USA. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, BLACKETT LAB, LONDON SW7 2BZ, ENGLAND. LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. JET PROPULS LAB, PASADENA, CA 91109 USA. RP NASA, GODDARD SPACE FLIGHT CTR, CODE 695, GREENBELT, MD 20771 USA. RI MacDowall, Robert/D-2773-2012 NR 5 TC 5 Z9 5 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 125 EP 128 DI 10.1007/BF00768767 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300023 ER PT J AU SMITH, EJ NEUGEBAUER, M BALOGH, A BAME, SJ LEPPING, RP TSURUTANI, BT AF SMITH, EJ NEUGEBAUER, M BALOGH, A BAME, SJ LEPPING, RP TSURUTANI, BT TI ULYSSES OBSERVATIONS OF LATITUDE GRADIENTS IN THE HELIOSPHERIC MAGNETIC-FIELD - RADIAL COMPONENT AND VARIANCES SO SPACE SCIENCE REVIEWS LA English DT Review ID SOLAR WIND AB The radial component of the magnetic field at Ulysses, over latitudes from -10 degrees to -45 degrees and distances from 5.3 to 3.8 AU, compares very well with corresponding measurements being made by IMP-8 in the ecliptic at 1AU. There is little, if any, evidence of a latitude gradient. Variances in the field, normalized to the square of the field magnitude, show little change with latitude in variations in the magnitude but a large increase in the transverse field variations. The latter are shown to be caused by the presence of large amplitude, long period Alfvenic fluctuations. This identification is based on the close relation between the magnetic field and velocity perturbations including the effect of anisotropy in the solar wind pressure. The waves are propagating outward from the Sun, as in the ecliptic, but variance analysis indicates that the direction of propagation is radial rather than field-aligned. A significant long-period component of greater than or equal to 10 hours is present. C1 UNIV LONDON IMPERIAL COLL SCI & TECHNOL, BLACKETT LAB, LONDON SW7 2BZ, ENGLAND. LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 13 TC 56 Z9 56 U1 0 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 165 EP 170 DI 10.1007/BF00768773 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300029 ER PT J AU BALOGH, A GONZALEZESPARZA, JA FORSYTH, RJ BURTON, ME GOLDSTEIN, BE SMITH, EJ BAME, SJ AF BALOGH, A GONZALEZESPARZA, JA FORSYTH, RJ BURTON, ME GOLDSTEIN, BE SMITH, EJ BAME, SJ TI INTERPLANETARY SHOCK-WAVES - ULYSSES OBSERVATIONS IN AND OUT OF THE ECLIPTIC-PLANE SO SPACE SCIENCE REVIEWS LA English DT Review ID AU AB Between its launch in October 1990 and the end of 1993, approximately 160 fast collisionless shock waves were observed in the solar wind by the Ulysses space probe. During the in-ecliptic part of the mission, to February 1992, the observed shock waves were first caused mainly by solar transient events following the solar maximum and the reorganisation of the large scale coronal fields. With the decay in solar activity, relatively stable Corotating Interaction Regions (CIRs) were observed betwen 3 and 5.4 AU, each associated with at least one forward-reverse shock pair. During the out-of-ecliptic phase of the orbit, from February 1992 onwards, CIRs and shock pairs associated with them continued to dominate the observations. From July 1992, Ulysses encountered the fast solar wind flow from the newly developed southern polar coronal hole, and from May 1993 remained in the unipolar magnetic region associated with this coronal hole. At latitudes beyond 30 degrees, CIRs were associated almost exclusively with reverse shocks only. A comprehensive list of shock waves identified in the magnetic field and solar wind plasma data from Ulysses is given in Table 1. The principal characteristics were determined mainly from the magnetic field data. General considerations concerning the determination of shock characteristics are outlined in the Introduction. C1 CALTECH, JET PROPULS LAB, PASADENA, CA USA. LOS ALAMOS NATL LAB, LOS ALAMOS, NM USA. RP UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, BLACKETT LAB, LONDON, ENGLAND. RI Gonzalez-Esparza, J. Americo/A-6720-2013 NR 13 TC 86 Z9 87 U1 0 U2 3 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 171 EP 180 DI 10.1007/BF00768774 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300030 ER PT J AU WINTERHALTER, D NEUGEBAUER, M GOLDSTEIN, BE SMITH, EJ TSURUTANI, BT BAME, SJ BALOGH, A AF WINTERHALTER, D NEUGEBAUER, M GOLDSTEIN, BE SMITH, EJ TSURUTANI, BT BAME, SJ BALOGH, A TI MAGNETIC HOLES IN THE SOLAR-WIND AND THEIR RELATION TO MIRROR-MODE STRUCTURES SO SPACE SCIENCE REVIEWS LA English DT Review ID ULYSSES AB Data obtained by the Ulysses magnetometer and solar wind analyzer have been combined to study the properties of magnetic holes in the solar wind between 1 and 5.4 AU and to 23 degrees south latitude. Although the plasma surrounding the holes was generally stable against the mirror instability, there are indications that the holes may have been remnants of mirror mode structures created upstream of the points of observation. Those indications include: (1) For the few holes for which proton or alpha-particle pressure could be measured inside the hole, the ion thermal pressure was always greater than in the plasma adjacent to the holes. (2) The plasma surrounding many of the holes was marginally stable for the mirror mode, while the plasma environment of all the holes was significantly closer to mirror instability than was the average solar wind. (3) The plasma containing trains of closely spaced holes was closer to mirror instability than was the plasma containing isolated holes. (4) The near-hole plasma had much higher ion beta (ratio of thermal to magnetic pressure) than did the average solar wind. C1 LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, BLACKETT LAB, LONDON SW7 2BZ, ENGLAND. RP CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 5 TC 31 Z9 32 U1 0 U2 1 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 201 EP 204 DI 10.1007/BF00768780 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300036 ER PT J AU TSURUTANI, BT SMITH, EJ HO, CM NEUGEBAUER, M GOLDSTEIN, BE MOK, JS AF TSURUTANI, BT SMITH, EJ HO, CM NEUGEBAUER, M GOLDSTEIN, BE MOK, JS TI INTERPLANETARY DISCONTINUITIES AND ALFVEN WAVES SO SPACE SCIENCE REVIEWS LA English DT Review ID SOLAR; STORMS AB The rate of occurrence of interplanetary discontinuities (ROID) is examined using Ulysses magnetic field and plasma data from 1 to 5 AU radial distance from the Sun and at high heliospheric latitudes. It is found that there are two regions in interplanetary space where the ROID is high: in stream-stream interaction regions and in Alfven wave trains. This latter feature is particularly obvious at high heliographic latitudes when Ulysses enters a high speed stream associated with a polar coronal hole. These streams are characterized by the presence of continuous, large-amplitude (Delta (B) over bar/\B\-1-2,) Alfven waves and an extraordinarily high ROID value (similar to 150 discontinuities/day). In a number of intervals examined, it is found that (rotational) discontinuities are an integral part of the Alfven wave: they represent similar to 90 degrees phase rotation of the wave out of the full 360 degrees rotation of the wave. These large amplitude nonlinear Alfven waves thus appear to be phase steepened. The nonlinear Alfven waves are spherically polarized, i.e., the tip of the perturbation vector resides on the surface of a sphere (a consequence of constant \B\). The best description of this wave plus discontinuity is a ''spherical are polarization''. C1 UNIV LONDON IMPERIAL COLL SCI & TECHNOL, BLACKETT LAB, LONDON SW7 2BZ, ENGLAND. LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. RP CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 12 TC 15 Z9 15 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 205 EP 210 DI 10.1007/BF00768781 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300037 ER PT J AU WOO, R ARMSTRONG, JW GAZIS, PR AF WOO, R ARMSTRONG, JW GAZIS, PR TI DOPPLER SCINTILLATION MEASUREMENTS OF THE HELIOSPHERIC CURRENT SHEET AND CORONAL STREAMERS CLOSE TO THE SUN SO SPACE SCIENCE REVIEWS LA English DT Review ID SOLAR-WIND STRUCTURE; INTERPLANETARY DISTURBANCES; SPECTRUM; CYCLE; TURBULENCE; EVOLUTION AB Prominent enhancements in Doppler scintillation lasting a fraction of a day (solar source several degrees wide) and overlying the neutral line represent the signature of the heliospheric current sheet and the apparent interplanetary manifestation of coronal streamers near the Sun. This first detection of coronal streamers in radio scintillation measurements provides the link between in situ measurements of the spatial wavenumber spectrum of electron density fluctuations beyond 0.3 AU and earlier measurements deduced from radio scintillation and scattering observations inside 0.3 AU. Significant differences between the density spectra of fast streams and slow solar wind associated with the heliospheric current sheet near the Sun reinforce the emerging picture that high- and low-speed flows are organized by the large-scale solar magnetic field, and that while the contrast between solar wind properties of the two flows is highest near the Sun, it undergoes substantial erosion in the ecliptic plane as the solar wind expands. C1 NASA, AMES RES CTR, SJSU FDN, MOFFETT FIELD, CA 94035 USA. RP CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 26 TC 8 Z9 8 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 223 EP 228 DI 10.1007/BF00768783 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300039 ER PT J AU BARNES, A AF BARNES, A TI MOTION OF THE HELIOSPHERIC TERMINATION SHOCK AT HIGH HELIOGRAPHIC LATITUDE SO SPACE SCIENCE REVIEWS LA English DT Review ID DISTANCE AB We expect the mean distance of the heliospheric termination shock to be greater (smaller) at polar latitudes than at equatorial latitudes, depending on whether the mean dynamic pressure of the solar wind is greater or smaller at high latitudes. The heliospheric termination shock is expected to move in response to variation in upstream solar wind conditions, so that at any particular instant the termination shock will resemble a distorted asymmetric balloon with some parts moving inward and others moving outward. If the shock is a gasdynamic or magnetohydrodynamic shock the results of the analysis depend only very weakly on the nature of the upstream disturbance; typical speeds of the disturbed shock are similar to 100 to 200 km/s. In the absence of a significant latitude gradient of the typical magnitude of solar wind disturbances typical motions of the disturbed shock at polar latitudes would be about twice as fast, due to the higher speed of the high-latitude wind. If the dynamics of the termination shock are dominated by acceleration of the anomalous component of the cosmic rays, the motion of the shock in response to a given disturbance is substantially slower than in the gasdynamic case. Conceivably, particle acceleration might be a less important effect at higher latitudes, and we envision the possibility of a termination shock that is dominated by particle acceleration at lower latitudes and is an MHD shock at high latitudes. In this event high latitude solar wind disturbances would produce substantially larger inward and outward motions of the shock in the polar regions. RP NASA, AMES RES CTR, THEORET STUDIES BRANCH, MOFFETT FIELD, CA 94035 USA. NR 14 TC 14 Z9 14 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 233 EP 236 DI 10.1007/BF00768785 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300041 ER PT J AU REINER, MJ FAINBERG, J STONE, RG AF REINER, MJ FAINBERG, J STONE, RG TI INTERPLANETARY TYPE-III RADIO-BURSTS OBSERVED FROM HIGH SOUTHERN HELIOGRAPHIC LATITUDES SO SPACE SCIENCE REVIEWS LA English DT Review ID SOLAR-WIND SPEED; MODEL INTERPRETATION; EMISSION; DENSITY; STORMS AB 3Type III radio bursts observed from high southern latitudes are analyzed far the first time. The continual observation of these radio bursts by Ulysses from after the Jupiter swing-by to 50 degrees S latitude argues for a wide latitudinal directivity of type III radiation. From this high latitude perspective, type III radio sources that lie in the far hemisphere of the Sun with respect to Ulysses are unambiguously resolved for the first time. Using the Ulysses direction-finding capabilities, the radio source locations in the 3-D heliosphere are derived for a radio event on 31 January 1994 when Ulysses was similar to 45 degrees S latitude. The source locations describe a spiral-like trajectory originating from the far side of the Sun. The angular radii of these radio sources are compared to angular radii that were previously derived from in-ecliptic observations. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP HUGHES STX CORP, LANHAM, MD 20706 USA. NR 15 TC 2 Z9 2 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 255 EP 260 DI 10.1007/BF00768788 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300044 ER PT J AU REINER, MJ ANDERSON, KA ROELOF, E ARMSTRONG, T HOSPODARSKY, GB FAINBERG, J STONE, RG LANZEROTTI, L GURNETT, DA PHILLIPS, JL FORSYTH, R AF REINER, MJ ANDERSON, KA ROELOF, E ARMSTRONG, T HOSPODARSKY, GB FAINBERG, J STONE, RG LANZEROTTI, L GURNETT, DA PHILLIPS, JL FORSYTH, R TI ULYSSES-GALILEO OBSERVATIONS OF TYPE-III RADIO-BURSTS AND ASSOCIATED IN-SITU ELECTRONS AND LANGMUIR-WAVES SO SPACE SCIENCE REVIEWS LA English DT Review ID CORONAL MASS EJECTA; SOLAR ELECTRONS; INTERPLANETARY MEDIUM; PROPAGATION AB Both the Ulysses and Galileo spacecraft detected energetic electrons and Langmuir waves that were associated with a type III radio burst on 10 December 1990. At the time of these observations, these spacecraft were in the ecliptic plane and separated by 0.4 AU, with Galileo near the Earth at 1 AU and Ulysses at 1.36 AU. From the measured electron arrival times, the propagation path lengths of the electrons to both Ulysses and Galileo were estimated to be significantly longer than the length of the Parker spiral. These long path lengths are interpreted as due to draping of the interplanetary magnetic field lines around a CME. The onset times of the Langmuir waves at Ulysses and Galileo coincided with the estimated arrival time of the 9 keV and 14 keV electrons, respectively. C1 UNIV CALIF BERKELEY, SPACE SCI LAB, BERKELEY, CA 94720 USA. JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD 20723 USA. UNIV KANSAS, DEPT PHYS & ASTRON, LAWRENCE, KS 66045 USA. UNIV IOWA, DEPT PHYS & ASTRON, IOWA CITY, IA 52242 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. AT&T BELL LABS, MURRAY HILL, NJ 07974 USA. LOS ALAMOS NATL LAB, LOS ALAMOS, NM 87545 USA. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, BLACKETT LAB, LONDON SW7 2BZ, ENGLAND. RP HUGHES STX CORP, LANHAM, MD 20706 USA. OI Hospodarsky, George/0000-0001-9200-9878 NR 12 TC 4 Z9 4 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 261 EP 266 DI 10.1007/BF00768789 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300045 ER PT J AU HOANG, S STEINBERG, JL REINER, MJ STONE, RG AF HOANG, S STEINBERG, JL REINER, MJ STONE, RG TI INTERPLANETARY TYPE-III RADIO-BURSTS OBSERVED SIMULTANEOUSLY BY ULYSSES AND ICE SO SPACE SCIENCE REVIEWS LA English DT Review AB We analyse two solar type III radio bursts that were observed simultaneously by the ICE and Ulysses spacecraft. Both bursts originated behind the solar limb as viewed from either spacecraft. At the time of these events, ICE was in the ecliptic plane at similar to 1 AU and Ulysses was similar to 350 south of the ecliptic plane at similar to 4 AU For one event on 931117, the ratios of the peak flux densities measured at each spacecraft, st each observing frequency, were consistent with the most probable source locations relative to ICE and Ulysses. The second event on 931004 was a complex burst consisting of two distinct components at high frequencies. At low frequencies, the intensity of the first component decreased rapidly at each spacecraft. The second component, however, dominated the low frequency emission observed at Ulysses but not at ICE. These differences in the observed radiation must be related to the different viewing geometries of the two spacecraft. The measured onset times as a function of observing frequency were consistent with a constant exciter speed through the interplanetary medium and suggest that there are significant propagation delays, especially for the radiation propagating within the ecliptic plane. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP OBSERV PARIS, DESPA, CNRS, URA 264, F-92195 MEUDON, FRANCE. NR 7 TC 1 Z9 1 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 267 EP 270 DI 10.1007/BF00768790 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300046 ER PT J AU SANDERSON, TR MARSDEN, RG WENZEL, KP BALOGH, A FORSYTH, RJ GOLDSTEIN, BE AF SANDERSON, TR MARSDEN, RG WENZEL, KP BALOGH, A FORSYTH, RJ GOLDSTEIN, BE TI HIGH-LATITUDE OBSERVATIONS OF ENERGETIC IONS DURING THE FIRST ULYSSES POLAR PASS SO SPACE SCIENCE REVIEWS LA English DT Review ID RECURRENT AB We present observations of energetic ions from the Ulysses COSPIN Low Energy Telescope in the mid and high-latitude regions of the heliosphere prior to and during the first polar pass of the Ulysses spacecraft. After the encounter with Jupiter, Ulysses started on its journey out-of-the-ecliptic. Between similar to 13 degrees S and similar to 29 degrees S the spacecraft sampled the solar wind from both the streamer belt and the polar coronal hole. Here, co-rotating magnetic structures with forward and reverse shocks and containing accelerated energetic ions were observed. At latitudes greater than similar to 29 degrees S, Ulysses was completely immersed in the solar wind from the polar coronal hole. Here the co-rotating magnetic structures were weaker, and in general had only reverse shocks, but were still capable of accelerating the energetic ions, albeit with reduced intensity. The most recent results show that beyond similar to 50 degrees S, very few if any, reverse shocks are observed. However, accelerated ions from magnetic interaction regions are still observed. We report also on an intensity enhancement at similar to 50 degrees S due to the passage of a high-latitude CME. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, BLACKETT LAB, LONDON SW7 2BZ, ENGLAND. CALTECH, JET PROPULS LAB, PASADENA, CA USA. RP EUROPEAN SPACE AGCY, ESTEC, DEPT SPACE SCI, F-75738 PARIS, FRANCE. NR 12 TC 12 Z9 12 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 291 EP 296 DI 10.1007/BF00768793 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300049 ER PT J AU GLOECKLER, G ROELOF, EC OGILVIE, KW BERDICHEVSKY, DB AF GLOECKLER, G ROELOF, EC OGILVIE, KW BERDICHEVSKY, DB TI PROTON PHASE-SPACE DENSITIES (0.5-EV-LESS-THAN-E(P)-LESS-THAN-5-MEV) AT MIDLATITUDES FROM ULYSSES-SWICS-HI-SCALE MEASUREMENTS SO SPACE SCIENCE REVIEWS LA English DT Review ID ENERGIES; IONS AB Proton phase space densities in the solar wind frame from suprathermal velocities 10 km s(-1) to 30,000 km s(-1) (0.5 eV-5 MeV) were derived from combined SWIGS and HISCALE measurements when Ulysses was at 5 AU and -24 degrees heliolatitude. The period (19-23 January 1993) encompasses a forward/reverse shock pair (20 January, 0500 UT and 22 January, 0300 UT). Strong evidence is found for shock acceleration of pickup protons from interstellar hydrogen at all energies measured. C1 JOHNS HOPKINS UNIV, APPL PHYS LAB, LAUREL, MD 20723 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. HUGHES STX CORP, LANHAM, MD 20706 USA. RP UNIV MARYLAND, DEPT PHYS & ASTRON, COLLEGE PK, MD 20742 USA. NR 7 TC 12 Z9 12 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 321 EP 326 DI 10.1007/BF00768798 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300054 ER PT J AU CHRISTIAN, ER COOPER, JF AF CHRISTIAN, ER COOPER, JF TI POLAR RAIN ENTRY OF GALACTIC ELECTRONS INTO THE INNER HELIOSPHERE SO SPACE SCIENCE REVIEWS LA English DT Review ID SOLAR MODULATION; MAGNETIC-FIELD; TRANSPORT; SHOCK; WIND AB The understanding of the relative intensity variations in cosmic ray ions and electrons with respect to solar modulation is a grand challenge for cosmic ray modulation theory. Although effects of the heliospheric neutral sheet, gradient-curvature drifts, and merged interaction regions provide qualitative explanations for observed solar cycle variations of high energy protons and ions, these effects do not account for the anomalously high intensities of high energy galactic electrons at 22-year intervals of the solar magnetic solar cycle. From the similar modulation responses of protons and heavy ions it does not appear that cosmic ray pressure effects, dominated by protons, can account for the charge-sign asymmetry of cosmic ray modulation. External factors including modulation in the heliosheath and polar linkage to the interstellar magnetic field are examined as potential causes of symmetry breaking for electron modulation with respect to the solar magnetic polarity at solar minimum. C1 NASA, GODDARD SPACE FLIGHT CTR, NATL SPACE SCI DATA CTR, HUGHES STX CORP, GREENBELT, MD 20771 USA. RP NASA, GODDARD SPACE FLIGHT CTR, USRA, HIGH ENERGY ASTROPHYS LAB, CODE 661, GREENBELT, MD 20771 USA. RI Cooper, John/D-4709-2012; Christian, Eric/D-4974-2012 OI Christian, Eric/0000-0003-2134-3937 NR 10 TC 0 Z9 0 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 415 EP 418 DI 10.1007/BF00768814 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300070 ER PT J AU MURPHY, N SMITH, EJ TSURUTANI, BT BALOGH, A SOUTHWOOD, DJ AF MURPHY, N SMITH, EJ TSURUTANI, BT BALOGH, A SOUTHWOOD, DJ TI FURTHER-STUDIES OF WAVES ACCOMPANYING THE SOLAR-WIND PICK-UP OF INTERSTELLAR HYDROGEN SO SPACE SCIENCE REVIEWS LA English DT Review AB Data collected by the magnetometer onboard the Ulysses spacecraft are surveyed for the occurrence of waves generated during the pick-up of interstellar hydrogen. Thirty one wave events were found during a 640 day study period between March 21, 1992 and December 20, 1993 (after the Ulysses encounter with Jupiter). It is found that observation of the waves does not depend on the magnitude of the background magnetic field, but is a strong function of the angle between the magnetic field and the solar wind flow direction, with small angles being favored. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, BLACKETT LAB, LONDON SW7 2BZ, ENGLAND. RP CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. NR 5 TC 34 Z9 34 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 447 EP 453 DI 10.1007/BF00768819 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300075 ER PT J AU BAGUHL, M GRUN, E HAMILTON, DP LINKERT, G RIEMANN, R STAUBACH, P ZOOK, HA AF BAGUHL, M GRUN, E HAMILTON, DP LINKERT, G RIEMANN, R STAUBACH, P ZOOK, HA TI THE FLUX OF INTERSTELLAR DUST OBSERVED BY ULYSSES AND GALILEO SO SPACE SCIENCE REVIEWS LA English DT Review DE INTERSTELLAR DUST; ULYSSES DUST MEASUREMENTS; GALILEO DUST MEASUREMENTS ID JUPITER AB Interstellar dust detected by the dust sensor onboard Ulysses was first identified after the Jupiter flyby when the spacecraft's trajectory changed dramatically (Grun et al., 1994). Here we report on two years of Ulysses post-Jupiter data covering the range of ecliptic latitudes from 0 degrees to -54 degrees and distances from 5.4 to 3.2 AU. We find that, over this time period, the flux of interstellar dust particles with a mean mass of 3.10(-13) g stays nearly constant at about 1.10-4 m(-2) s(-1) (pi sr)(-1) with both ecliptic latitude and heliocentric distance. Also presented are 20 months of measurements from the identical dust sensor onboard the Galileo spacecraft which moved along an in-ecliptic orbit from 1.0 to 4.2 AU. From the impact direction and speeds of the measured dust particles we conclude that Galileo almost certainly sensed interstellar dust outside 2.8 AU; interstellar particles may also account for part of the flux seen between 1 and 2.8 AU. C1 NASA, LYNDON B JOHNSON SPACE CTR, HOUSTON, TX 77058 USA. RP MAX PLANCK INST KERNPHYS, POB 103980, D-69029 HEIDELBERG, GERMANY. NR 9 TC 56 Z9 56 U1 0 U2 0 PU SPRINGER PI DORDRECHT PA VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS SN 0038-6308 EI 1572-9672 J9 SPACE SCI REV JI Space Sci. Rev. PD APR PY 1995 VL 72 IS 1-2 BP 471 EP 476 DI 10.1007/BF00768822 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QU893 UT WOS:A1995QU89300078 ER PT J AU LAWLESS, D JACKSON, CGR GREENLEAF, JE AF LAWLESS, D JACKSON, CGR GREENLEAF, JE TI EXERCISE AND HUMAN-IMMUNODEFICIENCY-VIRUS (HIV-1) INFECTION SO SPORTS MEDICINE LA English DT Article C1 NASA,AMES RES CTR,DIV LIFE SCI 23911,HUMAN ENVIRONM PHYSIOL LAB,MOFFETT FIELD,CA 94035. NR 0 TC 10 Z9 10 U1 2 U2 2 PU ADIS INTERNATIONAL LTD PI AUCKLAND PA 41 CENTORIAN DR, PRIVATE BAG 65901, MAIRANGI BAY, AUCKLAND 10, NEW ZEALAND SN 0112-1642 J9 SPORTS MED JI Sports Med. PD APR PY 1995 VL 19 IS 4 BP 235 EP 239 PG 5 WC Sport Sciences SC Sport Sciences GA QU247 UT WOS:A1995QU24700001 PM 7604196 ER PT J AU BONDAR, RL STEIN, F DUNPHY, PT MORADSHAHI, P RUBIN, M FORTNEY, S KASSAM, MS AF BONDAR, RL STEIN, F DUNPHY, PT MORADSHAHI, P RUBIN, M FORTNEY, S KASSAM, MS TI CEREBROVASCULAR RESPONSE TO GRADED TILT SO STROKE LA English DT Meeting Abstract C1 ST LOUIS UNIV,ST LOUIS,MO 63103. RYERSON POLYTECH UNIV,TORONTO,ON,CANADA. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER HEART ASSOC PI DALLAS PA 7272 GREENVILLE AVENUE, DALLAS, TX 75231-4596 SN 0039-2499 J9 STROKE JI Stroke PD APR PY 1995 VL 26 IS 4 BP 730 EP 730 PG 1 WC Clinical Neurology; Peripheral Vascular Disease SC Neurosciences & Neurology; Cardiovascular System & Cardiology GA QQ104 UT WOS:A1995QQ10400105 ER PT J AU BARTHELEMY, JFM HALL, LE AF BARTHELEMY, JFM HALL, LE TI AUTOMATIC DIFFERENTIATION AS A TOOL IN ENGINEERING DESIGN SO STRUCTURAL OPTIMIZATION LA English DT Article AB Automatic Differentiation (AD) is a tool that systematically implements the chain rule of differentiation to obtain the derivatives of functions calculated by computer programs. In this paper, it is assessed as a tool for engineering design. The paper discusses the forward and reverse modes of AD, their computing requirements, as well as approaches to implementing AD. It continues with the application of two different tools to two medium-size structural analysis problems to generate sensitivity information typically necessary in an optimization or design situation. The paper concludes with the observation that AD is to be preferred to finite differencing in most cases, as long as sufficient computer storage is available; in some instances, AD may be the alternative to consider in lieu of analytical sensitivity analysis. RP BARTHELEMY, JFM (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23665, USA. NR 0 TC 18 Z9 20 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0934-4373 J9 STRUCT OPTIMIZATION JI Struct. Optim. PD APR PY 1995 VL 9 IS 2 BP 76 EP 82 DI 10.1007/BF01758823 PG 7 WC Computer Science, Interdisciplinary Applications; Engineering, Multidisciplinary; Mechanics SC Computer Science; Engineering; Mechanics GA QT582 UT WOS:A1995QT58200002 ER PT J AU HUNLEY, JD AF HUNLEY, JD TI THE ENIGMA OF GODDARD,ROBERT,H SO TECHNOLOGY AND CULTURE LA English DT Article RP HUNLEY, JD (reprint author), NASA,HIST OFF,WASHINGTON,DC 20546, USA. NR 50 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0040-165X J9 TECHNOL CULT JI Technol. Cult. PD APR PY 1995 VL 36 IS 2 BP 327 EP 350 DI 10.2307/3106375 PG 24 WC History & Philosophy Of Science SC History & Philosophy of Science GA TB036 UT WOS:A1995TB03600005 ER PT J AU DIMOFTE, F AF DIMOFTE, F TI WAVE JOURNAL BEARING WITH COMPRESSIBLE LUBRICANT .2. A COMPARISON OF THE WAVE BEARING WITH A WAVE-GROOVE BEARING AND A LOBE BEARING SO TRIBOLOGY TRANSACTIONS LA English DT Article DE BEARINGS; FLUID-FILM BEARINGS; HYDRODYNAMIC; COMPRESSIBLE FLUIDS AB To identify the potential advantages of the wave journal bearing, a three-wave journal bearing was compared to both a three-wave-groove bearing (a wave bearing with axial grooves that isolate each wave) and a three-lobe bearing. The lobe bearing's profile was selected to approximate the wave journal bearing's profile. The lubricant ws assumed to be compressible (gas). The bearing number, Lambda, was parameterized from 0.01 to 100, and the eccentricity ratio, epsilon, was varied from 0 to 0.4. Data at bearing numbers 0.1, 1, and 50, and eccentricity ratios of 0.1 and 0.4, were selected as representative of the bearing performance. The calculated load capacity and the critical mass are presented for the three bearings. The wave bearing shows a better load capacity than the other bearings at any applied load and running regime. However, a high bearing numbers the lubricant compressibility effect is predominant and all three analyzed bearings show similar load capacity. The critical masses of the wave-groove and lobe bearing are greater than the critical mass of the wave bearing if the applied load is small. For low and intermediate bearing numbers the wave-groove bearing is more stable than the other bearings especially at low wave's amplitude ratio. The lobe bearing is more stable than the other analyzed bearings at high bearing numbers or at large preload ratios. If the applied load increases, the wave bearing dynamic performance is competitive with both wave-groove and lobe bearings. In addition, at high bearing numbers, the wave bearing could run stably for any allocated rotor mass over a wide range of wave position angle. Three wave bearings are more sensitive to the direction of the applied load than the other bearings especially at low and intermediate bearing numbers. Therefore, a careful selection of waves position angle has to be done to maximize the wave bearing performance. C1 NASA,LEWIS RES CTR,CLEVELAND,OH. RP DIMOFTE, F (reprint author), UNIV TOLEDO,2801 W BANCROFT ST,TOLEDO,OH 43606, USA. NR 12 TC 5 Z9 6 U1 0 U2 3 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 1995 VL 38 IS 2 BP 364 EP 372 DI 10.1080/10402009508983416 PG 9 WC Engineering, Mechanical SC Engineering GA QP544 UT WOS:A1995QP54400020 ER PT J AU MEIER, GH PETTIT, FS SMIALEK, JL AF MEIER, GH PETTIT, FS SMIALEK, JL TI THE EFFECTS OF REACTIVE ELEMENT ADDITIONS AND SULFUR REMOVAL ON THE ADHERENCE OF ALUMINA TO NI-BASE AND FE-BASE ALLOYS SO WERKSTOFFE UND KORROSION-MATERIALS AND CORROSION LA English DT Article ID OXIDE SCALE ADHERENCE; CR-AL ALLOYS; METAL INTERFACE; ADHESION; SEGREGATION; MECHANISM AB The effects of reactive element additions to alumina-forming alloys (single-crystal Ni-base and ferritic Fe-Cr-Al alloys) and the effect of hydrogen annealing to remove sulfur on the oxide adherence to these alloys have been studied. The results have shown that desulfurization by hydrogen annealing can result in improvements in cyclic oxidation comparable to that achieved by doping with reactive elements. The results have also shown that then is less stress generation during the cyclic oxidation of Y-doped FeCrAl compared to Ti-doped or desulfurized FeCrAl. This indicates that the growth mechanism, as well as the strength of the oxide/alloy interface, influences the ultimate oxidation morphology and stress state which will certainly affect the length of time the alumina remains protective. It has been shown to be possible to estimate the amount of sulfur available to segregate to the alloy/oxide interface and how this is influenced by reactive element additions or hydrogen annealing. If these calculations can be made more quantitative it should be possible to engineer alumina-forming alloys for optimum resistance to cyclic oxidation e.g. by combining an appropriate desulfurization treatment and choice of reactive element addition. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP MEIER, GH (reprint author), UNIV PITTSBURGH,DEPT MAT SCI & ENGN,848 BENEDUM HALL,PITTSBURGH,PA 15261, USA. NR 31 TC 19 Z9 19 U1 0 U2 3 PU VCH PUBLISHERS INC PI DEERFIELD BEACH PA 303 NW 12TH AVE, DEERFIELD BEACH, FL 33442-1788 SN 0947-5117 J9 WERKST KORROS JI Werkst. Korros.-Mater. Corros. PD APR PY 1995 VL 46 IS 4 BP 232 EP 240 PG 9 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA QX238 UT WOS:A1995QX23800006 ER PT J AU CONNERNEY, JEP SATOH, T AF CONNERNEY, JEP SATOH, T TI 3 PRESIDENTS SO SCIENCE LA English DT Letter RP CONNERNEY, JEP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771, USA. RI connerney, john/I-5127-2013; OI connerney, jack/0000-0001-7478-6462 NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAR 31 PY 1995 VL 267 IS 5206 BP 1891 EP 1892 DI 10.1126/science.267.5206.1891 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QQ068 UT WOS:A1995QQ06800006 PM 17770081 ER PT J AU HAMILTON, JM KIM, J WALEFFE, F AF HAMILTON, JM KIM, J WALEFFE, F TI REGENERATION MECHANISMS OF NEAR-WALL TURBULENCE STRUCTURES SO JOURNAL OF FLUID MECHANICS LA English DT Article ID BOUNDARY-LAYER; STREAMWISE VORTICES; FLOW; REGION AB Direct numerical simulations of a highly constrained plane Couette flow are employed to study the dynamics of the structures found in the near-wall region of turbulent flows. Starting from a fully developed turbulent flow, the dimensions of the computational domain are reduced to near the minimum values which will sustain turbulence. A remarkably well-defined, quasi-cyclic and spatially organized process of regeneration of near-wall structures is observed. This process is composed of three distinct phases: formation of streaks by streamwise vortices, breakdown of the streaks, and regeneration of the streamwise vortices. Each phase sets the stage for the next, and these processes are analysed in detail. The most novel results concern vortex regeneration, which is found to be a direct result of the breakdown of streaks that were originally formed by the vortices, and particular emphasis is placed on this process. The spanwise width of the computational domain corresponds closely to the typically observed spanwise spacing of near-wall streaks. When the width of the domain is further reduced, turbulence is no longer sustained. It is suggested that the observed spacing arises because the time scales of streak formation, breakdown and vortex regeneration become mismatched when the streak spacing is too small, and the regeneration cycle at that scale is broken. C1 STANFORD UNIV,CTR TURBULENCE RES,STANFORD,CA 94305. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. OI Kim, John/0000-0002-6369-9264 NR 24 TC 413 Z9 420 U1 3 U2 32 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 25 PY 1995 VL 287 BP 317 EP 348 DI 10.1017/S0022112095000978 PG 32 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA QR181 UT WOS:A1995QR18100015 ER PT J AU HABERLE, RM BELL, JF AF HABERLE, RM BELL, JF TI INTRODUCTION TO THE MSATT SPECIAL SECTION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Editorial Material RP HABERLE, RM (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 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-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5233 EP 5234 DI 10.1029/95JE00223 PG 2 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700001 ER PT J AU POLLACK, JB OCKERTBELL, ME SHEPARD, MK AF POLLACK, JB OCKERTBELL, ME SHEPARD, MK TI VIKING LANDER IMAGE-ANALYSIS OF MARTIAN ATMOSPHERIC DUST SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID BIDIRECTIONAL REFLECTANCE SPECTROSCOPY; NONSPHERICAL PARTICLES; VERTICAL STRUCTURE; LIGHT-SCATTERING; MARS ATMOSPHERE; STORMS; OPPOSITION; PHOTOMETRY; AEROSOLS AB We have reanalyzed three sets of Viking Lander 1 and 2 (VL1 and VL2) images of the Martian atmosphere to better evaluate the radiative properties of the atmospheric dust particles. The properties of interest are the first two moments of the size distribution, the single-scattering albedo, the dust single-scattering phase function, and the imaginary index of refraction. These properties provide a good definition of the influence that the atmospheric dust has on heating of the atmosphere. Our analysis represents a significant improvement over past analyses (Pollack et al. 1977, 1979) by deriving more accurate brightnesses closer to the sun, by carrying out more precise analyses of the data to acquire the quantities of interest, and by using a better representation of scattering by nonspherical particles. The improvements allow us to better define the diffraction peak and hence the size distribution of the particles. For a lognormal particle size distribution, the first two moments of the size distribution, weighted by the geometric cross section, are found. The geometric cross-section weighted mean radius (r(eff)) is found to be 1.85 +/- 0.3 mu m at VL2 during northern summer when dust loading was low and 1.52 +/- 0.3 mu m at VL1 during the first dust storm. In both cases the best cross-section weighted mean variance(v(eff)) of the size distribution is equal to 0.5 +/- 0.2 mu m. The changes in size distribution, and thus radiative properties, do not represent a substantial change in solar energy deposition in the atmosphere over the Pollack et al. (1977, 1979) estimates. C1 SAN JOSE STATE UNIV,DEPT METEOROL,SAN JOSE,CA 95192. WASHINGTON UNIV,DEPT EARTH & PLANETARY SCI,ST LOUIS,MO 63130. RP POLLACK, JB (reprint author), NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035, USA. NR 41 TC 137 Z9 138 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-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5235 EP 5250 DI 10.1029/94JE02640 PG 16 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700002 ER PT J AU CLANCY, RT LEE, SW GLADSTONE, GR MCMILLAN, WW ROUSCH, T AF CLANCY, RT LEE, SW GLADSTONE, GR MCMILLAN, WW ROUSCH, T TI A NEW MODEL FOR MARS ATMOSPHERIC DUST BASED UPON ANALYSIS OF ULTRAVIOLET THROUGH INFRARED OBSERVATIONS FROM MARINER-9, VIKING, AND PHOBOS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID REFLECTANCE SPECTROSCOPY; SURFACE-COMPOSITION; PHYSICAL-PROPERTIES; MARTIAN ATMOSPHERE; SIMULATIONS; MINERALOGY; PALAGONITE; SPECTRA; TEPHRA; STORMS AB We propose key modifications to the Toon et al. (1977) model of the particle size distribution and composition of Mars atmospheric dust, based on a variety of spacecraft and wavelength observations of the dust. A much broader (r(eff)variance similar to 0.8 mu m), smaller particle size (r(mode)similar to 0.02 mu m) distribution coupled with a ''palagonite-like'' composition is argued to fit the complete ultraviolet-to-30-mu m absorption properties of the dust better than the montmorillonite-basalt, r(eff)variance = 0.4 mu m, r(mode) = 0.40 dust model of Toon et al. Mariner 9 (infrared interferometer spectrometer) IRIS spectra of high atmospheric dust opacities during the 1971-1972 Mars global dust storm are analyzed in terms of the Toon et al. dust model, and a Hawaiian palagonite sample (Roush et al., 1991) with two different size distribution models incorporating smaller dust particle sizes. Viking Infrared Thermal Mapper (IRTM) emission-phase-function (EPF) observations at 9 mu m are analyzed to retrieve 9-mu m dust opacities coincident with solar band dust opacities obtained from the same EPF sequences (Clancy and Lee, 1991). These EPF dust opacities provide an independent measurement of the visible/9-mu m extinction opacity ratio (greater than or equal to 2) for Mars atmospheric dust, which is consistent with a previous measurement by Martin (1986). Model values for the visible/9-mu m opacity ratio and the ultraviolet and visible single-scattering albedos are calculated for the palagonite model with the smaller particle size distributions and compared to the same properties for the Toon ct al. model of dust. The montmorillonite model of the dust is found to fit the detailed shape of the dust 9-mu m absorption well. However, it predicts structured, deep absorptions at 20 mu m which are not observed and requires a separate ultraviolet-visible absorbing component to match the observed behavior of the dust in this wavelength region. The modeled palagonite does not match the 8- to 9-mu m absorption presented by the dust in the IRIS spectra, probably due to its low SiO2 content (31%). However, it does provide consistent levels of ultraviolet/visible absorption, 9- to 12-mu m absorption, and a lack of structured absorption at 20 mu m. The ratios of dust extinction opacities at visible, 9 mu m, and 30 mu m are strongly affected by the dust particle size distribution. The Toon et al. dust size distribution (r(mode) = 0.40, r(eff)variance = 0.4 mu m, r(cw mu) = 2.7 mu m) predicts the correct ratio of the 9- to 30-mu m opacity, but underpredicts the visible/9-mu m opacity ratio considerably (1 versus greater than or equal to 2). A similar particle distribution width with smaller particle sizes (r(mode) = 0.17, r(eff)variance = 0.4 mu m, r(cw mu) = mu m) will fit the observed visible/9-mu m opacity ratio, but overpredicts the observed 9-mu m/30-mu m opacity ratio. A smaller and much broader particle size distribution (r(mode) = 0.02, r(eff)variance = 0.8 mu m, r(cw mu) = 1.8 mu m) can fit both dust opacity ratios. Overall, the nanocrystalline structure of palagonite coupled with a smaller, broader distribution of dust particle sizes provides a more consistent fit than the Toon et al. model of the dust to the IRIS spectra, the observed visible/9-mu m dust opacity ratio, the Phobos occultation measurements of dust particle sizes (Chassefiere et al., 1992), and the weakness of surface near IR absorptions expected for clay minerals (Clark, 1992; Bell and Crisp, 1993). C1 UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. SW RES INST,SAN ANTONIO,TX 78284. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. SAN FRANCISCO STATE UNIV,DEPT GEOSCI,SAN FRANCISCO,CA 94132. RP CLANCY, RT (reprint author), SPACE SCI INST,SUITE 294,1234 INNOVAT DR,BOULDER,CO 80303, USA. NR 47 TC 135 Z9 136 U1 1 U2 5 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5251 EP 5263 DI 10.1029/94JE01885 PG 13 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700003 ER PT J AU KAHN, R AF KAHN, R TI TEMPERATURE-MEASUREMENTS OF A MARTIAN LOCAL DUST STORM SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID PHYSICAL-PROPERTIES; MARS ATMOSPHERE; DEVILS AB A technique Tor estimating the ground and near-ground atmospheric temperatures within a Martian local dust storm is presented. It is applied to soundings taken by the Viking orbiter infrared thermal mapper (IRTM) instrument at four times-of-day for one storm. Essentially, a comparison is made between infrared radiances emerging from the storm interior and those from the region surrounding the storm. Particle extinction properties are assumed to be independent of position in the storm region, and scattering properties must be selected arbitrarily. For the storm studied here, the ground temperature in the interior is at least 6 K cooler, whereas the near-ground atmospheric temperature may be less than or comparable to, those of the surroundings. The thermal structure of the storm interior did not change measurably between 11.5 and 16.6 hours local time. These observations favor theories of dust storm development in which regional winds rather than local, dust-driven convection inititate the mobilization of dust from the surface. It is also concluded that the optical properties of dust particles in this local storm differ from those observed by Mariner 9 during the 1971-1972 global dust storm. RP KAHN, R (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Kahn, Ralph/D-5371-2012 OI Kahn, Ralph/0000-0002-5234-6359 NR 33 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5265 EP 5275 DI 10.1029/94JE02766 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700004 ER PT J AU HAYASHI, JN JAKOSKY, BM HABERLE, RM AF HAYASHI, JN JAKOSKY, BM HABERLE, RM TI ATMOSPHERIC EFFECTS ON THE MAPPING OF MARTIAN THERMAL INERTIA AND THERMALLY DERIVED ALBEDO SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MARS; OPACITY AB We examine the effects of a dusty CO2 atmosphere on the thermal inertia and thermally derived albedo of Mars and we present a new map of thermal inertias. This new map was produced using a coupled surface atmosphere (CSA) model, dust opacities from Viking infrared thermal mapper (IRTM) data, and CO2 columns based on topography. The CSA model thermal inertias are smaller than the 2% model thermal inertias, with the difference largest at large thermal inertia. Although the difference between the thermal inertias obtained with the two models is moderate for much of the region studied, it is largest in regions of either high dust opacity or of topographic lows, including the Viking Lander 1 site and some geologically interesting regions. The CSA model thermally derived albedos do not accurately predict the IRTM measured albedos and are very similar to the thermally derived albedos obtained with models making the 2% assumption. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. UNIV COLORADO,DEPT GEOL SCI,BOULDER,CO 80309. RP HAYASHI, JN (reprint author), UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309, USA. NR 13 TC 27 Z9 27 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5277 EP 5284 DI 10.1029/94JE02449 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700005 ER PT J AU BELL, JF ROUSH, TL MORRIS, RV AF BELL, JF ROUSH, TL MORRIS, RV TI MIDINFRARED TRANSMISSION SPECTRA OF CRYSTALLINE AND NANOPHASE IRON-OXIDES OXYHYDROXIDES AND IMPLICATIONS FOR REMOTE-SENSING OF MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID HAWAIIAN PALAGONITIC SOIL; MAGNETIC-PROPERTIES; DUST; MINERALOGY; SPECTROSCOPY; HEMATITE; OXIDES; MOSSBAUER; REGIONS; TEPHRA AB Ferric-iron-bearing materials play an important role in the interpretation of visible to near-IR Mars spectra, and they may play a similarly important role in the analysis of new mid-IR spacecraft spectral observations to be obtained over the next decade. We review existing data on mid-IR transmission spectra of ferric oxides/oxyhydroxides and present new transmission spectra for ferric-bearing materials spanning a wide range of mineralogy and crystallinity. These materials include 11 samples of well-crystallized ferric oxides (hematite, maghemite, and magnetite) and ferric oxyhydroxides (goethite, lepidocrocite). We also report the first transmission spectra for purely nanophase ferric oxide samples that have been shown to exhibit spectral similarities to Mars in the visible to near-IR and we compare these data to previous and new transmission spectra of terrestrial palagonites. Most of these samples show numerous, diagnostic absorption features in the mid-IR due to Fe3+-O2- vibrational transitions, structural and/or bound OH, and/or silicates. These data indicate that high spatial resolution, moderate spectral resolution mid-IR ground-based and spacecraft observations of Mars may be able to detect and uniquely discriminate among different ferric-iron-bearing phases on the Martian surface or in the airborne dust. C1 SAN FRANCISCO STATE UNIV,DEPT GEOSCI,SAN FRANCISCO,CA 94132. NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH,HOUSTON,TX 77058. UNIV WASHINGTON,GEOL REMOTE SENSING LAB,SEATTLE,WA 98195. RP BELL, JF (reprint author), NASA,AMES RES CTR,NAT RES COUNCIL,DIV SPACE SCI,M-S 245-3,MOFFETT FIELD,CA 94035, USA. NR 51 TC 13 Z9 13 U1 2 U2 8 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5297 EP 5307 DI 10.1029/94JE01389 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700007 ER PT J AU ROUSH, TL BELL, JF AF ROUSH, TL BELL, JF TI THERMAL EMISSION MEASUREMENTS 2000-400 CM-1 (5-25 MU-M) OF HAWAIIAN PALAGONITIC SOILS AND THEIR IMPLICATIONS FOR MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MAGNETIC-PROPERTIES; SURFACE-COMPOSITION; DUST; SPECTROSCOPY; SPECTRA; MINERALOGY; HEMATITE; TEPHRA; ROCKS AB The thermal emission of two palagonitic soils, common visible and near infrared spectral analogs for bright soils on Mars, was measured over the wavelength range of 5 to 25 mu m (2000 to 400 cm(-1)) for several particle size separates. All spectra exhibit emissivity features due to vibrations associated with H2O and SiO. The maximum variability of emissivity is approximate to 20% in the short wavelength region (5 to 6.5 mu m, 2000 to 1500 cm(-1)), and is more subdued, <4%, at longer wavelengths. The strengths of features present in infrared spectra of Mars cannot be solely provided by emissivity variations of palagonite; some other material or mechanism must provide additional absorption(s). C1 NASA,AMES RES CTR,NAT RES COUNCIL,MOFFETT FIELD,CA 94035. RP ROUSH, TL (reprint author), SAN FRANCISCO STATE UNIV,DEPT GEOSCI,SAN FRANCISCO,CA 94132, USA. NR 60 TC 19 Z9 19 U1 1 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5309 EP 5317 DI 10.1029/94JE02448 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700008 ER PT J AU MORRIS, RV GOLDEN, DC BELL, JF LAUER, HV AF MORRIS, RV GOLDEN, DC BELL, JF LAUER, HV TI HEMATITE, PYROXENE, AND PHYLLOSILICATES ON MARS - IMPLICATIONS FROM OXIDIZED IMPACT MELT ROCKS FROM MANICOUAGAN CRATER, QUEBEC, CANADA SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID HAWAIIAN PALAGONITIC SOIL; MAGNETIC-PROPERTIES; HYDROTHERMAL ALTERATION; MARTIAN FINES; IRON-OXIDES; DUST; SPECTROSCOPY; REFLECTANCE; MINERALOGY; NANOPHASE AB Visible and near-IR reflectivity, Mossbauer, and X ray diffraction data were obtained on powders of impact melt rock from the Manicouagan Impact Crater located in Quebec, Canada. The iron mineralogy is dominated by pyroxene for the least oxidized samples and by hematite for the most oxidized samples. Phyllosilicate (smectite) contents up to similar to 15 wt % were found in some heavily oxidized samples. Nanophase hematite and/or paramagnetic ferric iron is observed in all samples. No hydrous ferric oxides (e.g., goethite, lepidocrocite, and ferrihydrite) were detected, which implies the alteration occurred above 250 degrees C. Oxidative alteration is thought to have occurred predominantly during late-stage crystallization and subsolidus cooling of the impact melt by invasion of oxidizing vapors and/or solutions while the impact melt rocks were still hot. The near-IR band minimum correlated with the extent of aleration (Fe3+/Fe-tot) and ranged from similar to 1000 nm (high-Ca pyroxene) to similar to 850 nm (bulk, well-crystalline hematite) for least and most oxidized samples, respectively. Intermediate band positions (900-920 nm) are attributed to low-Ca pyroxene and/or a composite band from hematite-pyroxene assemblages. Manicouagan data are consistent with previous assignments of hematite and pyroxene to the similar to 850 and similar to 1000 nm bands observed in Martian reflectivity spectra. Manicouagan data also shaw that possible assignments for intermediate band positions (900-920 nm) in Martian spectra are pyroxene and/or hematite-pyroxene assemblages. By analogy with impact melt sheets and in agreement with observables for Mars, oxidative alteration of Martian impact melt sheets above 250 degrees C and subsequent erosion could produce rocks and soils with variable proportions of hematite (both bulk and nanophase), pyroxene, and phyllosilicates as iron-bearing mineralogies. If this process is dominant, these phases on Mars were formed rapidly at relatively high temperatures on a sporadic basis throughout the history of the planet. The Manicouagan samples also show that this mineralogical diversity can be accomplished at constant chemical composition, which is also indicated for Mars from analyses of soil at the two Viking landing sites. C1 DUAL INC,HOUSTON,TX. NASA,AMES RES CTR,NAT RES COUNCIL,MOFFETT FIELD,CA 94035. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. RP MORRIS, RV (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,CODE SN4,HOUSTON,TX 77058, USA. NR 40 TC 50 Z9 50 U1 0 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5319 EP 5328 DI 10.1029/94JE01500 PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700009 ER PT J AU ZENT, AP QUINN, RC AF ZENT, AP QUINN, RC TI SIMULTANEOUS ADSORPTION OF CO2 AND H2O UNDER MARS-LIKE CONDITIONS AND APPLICATION TO THE EVOLUTION OF THE MARTIAN CLIMATE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID CARBON-DIOXIDE; WATER-VAPOR; OBLIQUITY; REGOLITH; ATMOSPHERE; ICE AB The Martian regolith is the most substantial volatile reservoir on the planet. estimates of its adsorbed inventory have been based on simple measurements of the adsorption of either water or CO2 in isolation. Under some conditions, H2O can poison adsorbate surfaces, such that CO2 uptake is greatly reduced. We have made the first measurements of the simultaneous adsorption of CO2 and H2O under conditions appropriate to the Martian regolith and have found that at H2O monolayer coverage above about 0.5, CO2 begins to be displaced into the gas phase. We have developed an empirical expression that describes our co-adsorption data and have applied it to standard models of the Martian regolith. We find that currently, H2O does not substantially displace CO2, implying that the adsorbate inventories previously derived may be accurate, not more than 3-4 kPa (30-40 mbar). No substantial increase in atmospheric pressure is predicted at higher obliquities because high-latitude ground ice buffers the partial pressure of H2O in the pores, preventing high monolayer coverages of H2O from displacing CO2. The peak atmospheric pressure at high obliquity does increase as the total inventory of exchangeable CO2 increases. RP ZENT, AP (reprint author), NASA,AMES RES CTR,INST SETI,DIV SPACE SCI,MS 245-7,MOFFETT FIELD,CA 94035, USA. NR 28 TC 55 Z9 55 U1 2 U2 10 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5341 EP 5349 DI 10.1029/94JE01899 PG 9 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700011 ER PT J AU MOORE, JM CLOW, GD DAVIS, WL GULICK, VC JANKE, DR MCKAY, CP STOKER, CR ZENT, AP AF MOORE, JM CLOW, GD DAVIS, WL GULICK, VC JANKE, DR MCKAY, CP STOKER, CR ZENT, AP TI THE CIRCUM-CHRYSE REGION AS A POSSIBLE EXAMPLE OF A HYDROLOGIC-CYCLE ON MARS - GEOLOGIC OBSERVATIONS AND THEORETICAL EVALUATION SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID ICE; WATER; CHANNELS; SURFACE; BASINS; SNOW AB The transection and superposition relationships among channels, chaos, surface materials units, and other features in the circum-Chryse region of Mars were used to evaluate relative age relationships and evolution of flood events. Channels and chaos in contact (with one another) were treated as single discrete flood-canted systems. Some outflow channel systems form networks and are inferred to have been created by multiple flood events. Within some outflow channel networks, several separate individual channel systems can be traced to a specific chaos which acted as flood-source area to that specific flood channel. Individual flood-carved systems were related to widespread materials units or other surface features that served as stratigraphic horizons. Chryse outflow channels are inferred to have formed over most of the perceivable history of Mars. Outflow channels are inferred to become younger with increasing proximity to the Chryse basin. In addition, outflow channels closer to the basin show a greater diversity in age. The relationship of subsequent outflow channel sources to the sources of earlier floods is inferred to disfavor episodic flooding due to the progressive tapping of a juvenile nearsurface water supply. Instead, we propose the circum-Chryse region as a candidate site of past hydrological recycling. The discharge rates necessary to carve the circum-Chryse outflow channels would have inevitably formed temporary standing bodies of H2O on the Martian surface where the flood-waters stagnated and pooled (the Chryse basin is topographically enclosed). These observations and inferences have led us to formulate and evaluate two hypotheses: (1) large amounts of the sublimated H2O off the Chryse basin flood lakes precipitated (snowed) onto the flood-source highlands and this H2O was incorporated into the near surface, recharging the H2O sources, making possible subsequent deluges; and (2) ponded flood-water in Chryse basin drained back down an anti basinward dipping subsurface layer accessed along the southern edge of the lake, recharging the flood-source aquifers. H2O not redeposited in the flood-source region was largely lost to the hydrologic cycle. This loss progressively lowered the vitality of the cycle, probably by now killing it. Our numerical evaluations indicate that of the two hypotheses we formulated, the groundwater seep cycle seems by far the more viable. Optimally, similar to 3/4 of the original mass of an ice-covered cylindrical lake (albedo 0.5, 1 km deep, 100-km radius, draining along its rim for one quarter of its circumference into substrata with a permeability of 3000 darcies) can be modeled to have moved underground (on timescales of the order of 10(3) years) before the competing mechanisms of sublimation and freeze down choked off further water removal. Once underground, this water can travel distances equal to the separation between Chryse basin and flood-source sites in geologically short (similar to 10(6) year-scale) times. Conversely, we calculate that optimally only similar to 40% of the H2O carried from Chryse can condense at the highlands, and most of the precipitate would either collect at the base of the highlands/lowlands scarp or sublimate at rates greater than it would accumulate over the flood-source sites. Further observations from forthcoming missions may permit the determination of which mechanisms may have operated to recycle the Chryse flood-waters. C1 NASA,AMES RES CTR,INST SETI,MOFFETT FIELD,CA 94035. ARIZONA STATE UNIV,DEPT GEOG,TEMPE,AZ 85287. US GEOL SURVEY,ASTROGEOL BRANCH,MENLO PK,CA 94025. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP MOORE, JM (reprint author), NASA,AMES RES CTR,CTR MARS EXPLORAT,MS 245-3,MOFFETT FIELD,CA 94035, USA. NR 49 TC 34 Z9 34 U1 0 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5433 EP 5447 DI 10.1029/94JE08205 PG 15 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700017 PM 11539570 ER PT J AU WHITMIRE, DP DOYLE, LR REYNOLDS, RT MATESE, JJ AF WHITMIRE, DP DOYLE, LR REYNOLDS, RT MATESE, JJ TI A SLIGHTLY MORE MASSIVE YOUNG SUN AS AN EXPLANATION FOR WARM TEMPERATURES ON EARLY MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MAIN-SEQUENCE STARS; SOLAR-TYPE STARS; LITHIUM; LUMINOSITY; EVOLUTION; MODELS; WINDS; ATMOSPHERES; SPECTRUM; CLIMATE AB The valley network channels on the heavily cratered ancient surface of Mars suggest the presence of liquid water similar to 3.8 Gyr ago. However, the implied warm climate is difficult to explain in the context of the standard solar model, even allowing for the maximum CO2 greenhouse heating. in this paper we investigate the astronomical and planetary implications of a nonstandard solar model in which the zero-age, main-sequence Sun had a mass of 1.05 +/- 0.02 M(circle dot). The excess mass was subsequently lost in a solar wind during the first 1.2(+0.4)(-0.2) Gyr of the Sun's main sequence phase. The implied mass-loss rate of 4(-2)(+3) x 10(-11) M(circle dot) yr(-1), or about 10(3) x that of the current Sun, may be detectable in several nearby young solar type stars. C1 UNIV SW LOUISIANA,DEPT PHYS,LAFAYETTE,LA 70504. SETI INST,MT VIEW,CA 94043. NASA,AMES RES CTR,THEORET STUDIES BRANCH,MOFFETT FIELD,CA 94035. NR 55 TC 26 Z9 26 U1 0 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5457 EP 5464 DI 10.1029/94JE03080 PG 8 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700019 PM 11539571 ER PT J AU SANTEE, ML CRISP, D AF SANTEE, ML CRISP, D TI DIAGNOSTIC CALCULATIONS OF THE CIRCULATION IN THE MARTIAN ATMOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID GENERALIZED ELIASSEN-PALM; MIDDLE ATMOSPHERE; DIABATIC CIRCULATION; RADIATIVE-TRANSFER; THERMAL STRUCTURE; MARS ATMOSPHERE; DUST STORMS; MEAN CIRCULATION; POLAR-CAP; MODEL AB The circulation of the Martian atmosphere during late southern summer is derived from atmospheric temperature and dust distributions retrieved from a subset of the Mariner 9 infrared interferometer spectrometer (IRIS) thermal emission spectra (L(S) = 343 degrees-348 degrees) (Santee and Crisp, 1993). Zonal-mean zonal winds are calculated by assuming gradient wind balance and zero surface zonal wind. Both hemispheres have intense midlatitude westerly jets with velocities of 80-90 m/s near 50 km; in the southern tropics the winds are easterly with velocities of 40 m/s near 50 km. The net effect of the zonal-mean meridional circulation and large-scale waves can be approximated by the diabatic circulation, which is defined from the atmospheric thermal structure and net radiative heating rates. The radiative transfer model described by Crisp (1990) and Santee (1993) is used to compute solar heating and thermal cooling rates from diurnal averages of the retrieved IRIS temperature and dust distributions. At pressures below 4 mbar, there are large net radiative heating rates (up to 5 K/d) in the equatorial region and large net radiative cooling rates (up to 12 K/d) in the polar regions. These net radiative heating rates are used in a diagnostic stream function model which solves for the meridional and vertical components of the diabatic circulation simultaneously. We find a two-cell circulation, with rising motion over the equator, poleward flow in both hemispheres, sinking motion over both polar regions, and return flow in the lowest atmospheric levels. The maximum poleward velocity is 3 m/s in the tropics at similar to 55 km altitude, and the maximum vertical velocity is 2.5 cm/s downward over the north pole at similar to 60 km altitude. If these large transport rates are sustained for an entire season, the Martian atmosphere above the l-mbar level is overturned in about 38 days. This diabatic circulation is qualitatively similar to the terrestrial diabatic circulation at the comparable season, but is more vigorous. C1 CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,PASADENA,CA 91109. CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. NR 84 TC 17 Z9 18 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD MAR 25 PY 1995 VL 100 IS E3 BP 5465 EP 5484 DI 10.1029/94JE03207 PG 20 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN877 UT WOS:A1995QN87700020 ER PT J AU FRIMER, AA KINDER, JD YOUNGS, WJ MEADOR, MAB AF FRIMER, AA KINDER, JD YOUNGS, WJ MEADOR, MAB TI REINVESTIGATION OF THE PHOTOCYCLIZATION OF 1,4-PHENYLENE BIS(PHENYLMALEIC ANHYDRIDE) - PREPARATION AND STRUCTURE OF [5]HELICENE 5,6-9,10-DIANHYDRIDE SO JOURNAL OF ORGANIC CHEMISTRY LA English DT Article AB The I-2-catalyzed photooxidative cyclization of 1,4-phenylene bis(phenylmaleic anhydride) [PPMA] yields two products in an overall yield approaching 80%. Contrary to a previous report, the major product has been identified by X-ray crystallography as the novel [5]helicene-5,6,9,10-tetracarboxylic 5,6:9,10-dianhydride [HLDA], while the minor product (<5% yield) is the isomeric dibenz[ah]anthracene-5,6,12,13-tetracarboxylic 5,6:12,13-dianhydride [DBAA]. Partial irradiation permits the isolation of the monocyclization intermediate PMPA, which under the photolysis conditions generates the observed dicyclization products. Unlike HLDA, DBAA resists prolonged methanolysis to the corresponding acid esters. This confirms molecular modeling predictions that the 1,6-interaction between the H-4, H-7, H-11, and H-14 aromatic hydrogens and the corresponding neighboring carbonyl oxygens in DBAA inhibit opening of the resulting O-CO anhydride bond. Noteworthy as well is that HLDA, unlike the parent [5]helicene, resists further photocyclization under the reaction conditions to the:corresponding benzo[ghi]perylene. AM1 semiempirical calculations indicate that, contrary to [5]helicene, there is no buildup of bonding interaction between the designated bonding carbons (C-1 and C-14) as one goes from the HOMO to the corresponding LUMO. C1 BAR ILAN UNIV,DEPT CHEM,DAVID RESNICK CHAIR ACT OXYGEN CHEM,IL-52900 RAMAT GAN,ISRAEL. RP FRIMER, AA (reprint author), NASA,LEWIS RES CTR,POLYMER BRANCH,CLEVELAND,OH 44135, USA. OI Meador, Mary Ann/0000-0003-2513-7372 NR 41 TC 18 Z9 18 U1 1 U2 4 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0022-3263 J9 J ORG CHEM JI J. Org. Chem. PD MAR 24 PY 1995 VL 60 IS 6 BP 1658 EP 1664 DI 10.1021/jo00111a026 PG 7 WC Chemistry, Organic SC Chemistry GA QN888 UT WOS:A1995QN88800026 ER PT J AU HUDER, KJ DEMORE, WB AF HUDER, KJ DEMORE, WB TI ABSORPTION CROSS-SECTIONS OF THE CLO DIMER SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Letter ID PHOTODISSOCIATION; SPECTRUM; CL2O2; NM AB The absorption cross sections of the ClO dimer, ClOOCl, are important to the photochemistry of ozone depletion in the Antarctic. In this work new measurements were made of the dimer cross sections at 195 K. The results yield somewhat lower values in the long wavelength region, compared to those currently recommended in the NASA data evaluation (JPL 94-26). The corresponding solar photodissociation rates in the Antarctic are reduced by about 40%. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 9 TC 58 Z9 58 U1 0 U2 0 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD MAR 23 PY 1995 VL 99 IS 12 BP 3905 EP 3908 DI 10.1021/j100012a007 PG 4 WC Chemistry, Physical SC Chemistry GA QN632 UT WOS:A1995QN63200007 ER PT J AU DYALL, KG AF DYALL, KG TI THE CHOICE OF A ZEROTH-ORDER HAMILTONIAN FOR 2ND-ORDER PERTURBATION-THEORY WITH A COMPLETE ACTIVE SPACE SELF-CONSISTENT-FIELD REFERENCE FUNCTION SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID MOLLER-PLESSET SERIES; OPEN-SHELL; WAVE-FUNCTIONS; CONVERGENCE; ACCELERATION; MOLECULES; STATE; ENERGIES; SINGLET; SYSTEMS RP DYALL, KG (reprint author), NASA, AMES RES CTR, INST THERMOSCI, MAIL STOP 230-3, MOFFETT FIELD, CA 94035 USA. NR 50 TC 142 Z9 143 U1 2 U2 8 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 22 PY 1995 VL 102 IS 12 BP 4909 EP 4918 DI 10.1063/1.469539 PG 10 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QM507 UT WOS:A1995QM50700020 ER PT J AU DOLAN, JF MICHALITSIANOS, AG THOMPSON, RW BOYD, PT WOLINSKI, KG BLESS, RC NELSON, MJ PERCIVAL, JW TAYLOR, MJ ELLIOT, JL VANCITTERS, GW AF DOLAN, JF MICHALITSIANOS, AG THOMPSON, RW BOYD, PT WOLINSKI, KG BLESS, RC NELSON, MJ PERCIVAL, JW TAYLOR, MJ ELLIOT, JL VANCITTERS, GW TI THE GRAVITATIONAL LENS SYSTEM Q0957+561 IN THE ULTRAVIOLET SO ASTROPHYSICAL JOURNAL LA English DT Article DE GRAVITATIONAL LENSING; POLARIZATION; QUASARS, INDIVIDUAL (Q0957 + 561); ULTRAVIOLET, GALAXIES ID ACTIVE GALACTIC NUCLEI; TWIN QSO 0957+561; QUASAR 0957+561; LINEAR-POLARIZATION; TIME-DELAY; EMISSION; VARIABILITY; GALAXY; IMAGES; MODELS AB Photometric and polarimetric observations of both images of the gravitationally lensed quasar Q0957 + 561 (z(em) = 1.41) were obtained in the UV in 1993 with the High Speed Photometer on board the Hubble Space Telescope. The images exhibited no significant polarization in a bandpass centered on 2770 Angstrom (observer's frame); p less than or equal to 3.2% (2 sigma upper limit) in each image. The ratio of the flux density in image A to that in image B in late 1993 had a constant value, 1.021 +/- 0.008, in four different UV bandpasses between 1400 Angstrom and 3040 Angstrom (observer's frame). These results are consistent with the prediction of the gravitational lens interpretation that the photometric ratio of the images measured simultaneously should be independent of frequency. Reprocessed archival spectra of the two images obtained between 1981 and 1983 by the International Ultraviolet Explorer show that the photometric ratio of A to B varies between 0.96 and 2.0 in the Ly alpha emission line, and between 0.77 and 1.8 in the O VI 3,1037 emission line (quasar rest frame). The photometric ratio of A to B at any single epoch is often significantly different in the two emission lines. Accepting the system as a gravitational lens implies that in the quasar the flux in the Ly alpha emission line can vary independently of the flux in the O VI emission line. C1 UNIV WISCONSIN,DEPT ASTRON,MADISON,WI 53706. UNIV WISCONSIN,SPACE ASTRON LAB,MADISON,WI 53706. MIT,DEPT EARTH ATMOSPHER & PLANETARY SCI,CAMBRIDGE,MA 02139. NATL SCI FDN,DIV ASTRON SCI,ARLINGTON,VA 22230. UNIV SPACE RES ASSOC,WASHINGTON,DC. RP DOLAN, JF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771, USA. RI Boyd, Patricia/D-3274-2012 NR 38 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 20 PY 1995 VL 442 IS 1 BP 87 EP 90 DI 10.1086/175425 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QM747 UT WOS:A1995QM74700010 ER PT J AU LIN, YC BERTSCH, DL DINGUS, BL ESPOSITO, JA FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C MUKERJEE, R NOLAN, PL SCHNEID, E SREEKUMAR, P THOMPSON, DJ AF LIN, YC BERTSCH, DL DINGUS, BL ESPOSITO, JA FICHTEL, CE HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA MAYERHASSELWANDER, HA MICHELSON, PF VONMONTIGNY, C MUKERJEE, R NOLAN, PL SCHNEID, E SREEKUMAR, P THOMPSON, DJ TI EGRET OBSERVATIONS OF THE BL-LACERTAE OBJECT-0716+714 AND OBJECT-0521-365 SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL LACERTAE OBJECTS, INDIVIDUAL (0716+714, 0521-365); GAMMA RAYS, OBSERVATIONS ID EXTRAGALACTIC RADIO-SOURCES; ACTIVE GALACTIC NUCLEI; LAC OBJECTS; RAPID VARIABILITY; COMPLETE SAMPLE; PKS 0521-36; OPTICAL VARIABILITY; S5 SURVEY; SPECTRUM; BLAZARS AB During the Compton Observatory's viewing programs Phase 1 (1991 April to 1992 November, also known as the All-Sky Survey) and Phase 2 (1992 November to 1993 September), the BL Lac object 0716 + 714 was in the field of view of the EGRET telescope a total of six times, three times in Phase 1 and three more times in Phase 2, while the BL Lac object 0521 - 365 was in the field of view of EGRET only once in Phase 1. The source 0716 + 714 was detected in high-energy gamma rays by EGRET at a flux level of (2.0 +/- 0.4) x 10(-7) photons cm(-2) s(-1) for E > 100 MeV with a 6 sigma significance when it was first observed by EGRET in 1992 January 10 to 23. The corresponding spectral slope of the photon number distribution is determined to be -2.04 +/- 0.33. The gamma-ray flux of 0716 + 714 showed considerable time variability in subsequent EGRET observations. But the spectral slope stayed about the same within the statistical uncertainties of the EGRET data. The average spectral slope of the four viewing periods during which the photon flux of 0716 + 714 stayed above the EGRET detection threshold is found to be -1.85 +/- 0.20 from the combined data. The source 0521 + 365 was detected by EGRET in 1992 May 14 to June 4 at a flux level of (1.8 + 0.5) x 10(-7) photons cm(-2) s(-1) for E > 100 MeV with a 4 sigma significance. The corresponding spectral slope of the photon number distribution is found to be 2.161 +/- 0.36. Details of the observations of these two BL Lac objects with the EGRET telescope are presented. C1 MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. NORTHROP GRUMMAN CORP,BETHPAGE,NY 11714. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,GREENBELT,MD 20771. RP LIN, YC (reprint author), STANFORD UNIV,WW HANSEN EXPTL PHYS LAB,STANFORD,CA 94305, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; OI Thompson, David/0000-0001-5217-9135; Dingus, Brenda/0000-0001-8451-7450 NR 81 TC 45 Z9 47 U1 1 U2 1 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 1995 VL 442 IS 1 BP 96 EP 104 DI 10.1086/175427 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QM747 UT WOS:A1995QM74700012 ER PT J AU ROBINSON, RD CARPENTER, KG AF ROBINSON, RD CARPENTER, KG TI MG-II H-PROFILE AND K-PROFILE IN HIGH-LUMINOSITY, LATE-TYPE STARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, LATE-TYPE; SUPERGIANTS; ULTRAVIOLET, STARS ID MASS-LOSS; OUTER ATMOSPHERES; CHROMOSPHERES; ABSORPTION; LINES AB Using high-resolution spectroscopic data taken with the Goddard High Resolution Spectrograph aboard the Hubble Space Telescope and with the International Ultraviolet Explorer satellite, we compare the profiles of the Mg II h and k lines seen in stars with spectral types ranging from early K through mid-M and luminosities from giants to supergiants. For all of these stars the lines are broad emission features with a central absorption. When plotted on a velocity scale the absorption features of the h and k lines agree very well in both shape and position, as do the blue wings of the emission component. The red wings of the emission, however, show a pronounced difference, with the k line wing consistently shifted to the red of the h line wing. At present the reason for this discrepancy is unknown, but we suggest several possibilities, including radiative transfer effects and high-speed stellar winds. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP ROBINSON, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,COMP SCI CORP,ASTRON PROGRAM,CODE 681,GREENBELT,MD 20771, USA. RI Carpenter, Kenneth/D-4740-2012 NR 23 TC 18 Z9 18 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 1995 VL 442 IS 1 BP 328 EP 336 DI 10.1086/175443 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QM747 UT WOS:A1995QM74700028 ER PT J AU SCHNEIDER, JP NORBURY, JW CUCINOTTA, FA AF SCHNEIDER, JP NORBURY, JW CUCINOTTA, FA TI PARAMETERIZATION OF SPECTRAL DISTRIBUTIONS FOR PION AND KAON PRODUCTION IN PROTON-PROTON COLLISIONS SO ASTROPHYSICAL JOURNAL LA English DT Meeting Abstract C1 UNIV WISCONSIN,DEPT PHYS,MADISON,WI 53706. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 0 TC 0 Z9 0 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 1995 VL 442 IS 1 BP 455 EP 455 PN 1 PG 1 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QM747 UT WOS:A1995QM74700048 ER PT J AU ROSNER, R MUSIELAK, ZE CATTANEO, F MOORE, RL SUESS, ST AF ROSNER, R MUSIELAK, ZE CATTANEO, F MOORE, RL SUESS, ST TI ON THE ORIGIN OF DIVIDING LINES FOR LATE-TYPE GIANTS AND SUPERGIANTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE STARS, CORONAE; STARS, MASS LOSS; STARS, MAGNETIC FIELDS; SUPERGIANTS ID LATE-TYPE STARS; H-R DIAGRAM; X-RAY; STELLAR ATMOSPHERES; OUTER ATMOSPHERES; MAGNETIC BRAKING; MAIN-SEQUENCE; ALFVEN WAVES; COOL STARS; MASS-LOSS AB We show how a change in the nature of the stellar dynamo can lead to a transition in the topological character of stellar magnetic fields of evolved stars, from being mainly closed on the blueward side of the giant tracks in the H-R diagram to being mainly open on their redward side. If such a topological transition occurs, then these stars naturally segregate into two classes: those having hot coronae on the blueward side, and those having massive cool winds on the redward side, thus leading naturally to the so-called dividing lines. C1 UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP ROSNER, R (reprint author), UNIV CHICAGO,DEPT ASTRON & ASTROPHYS,5640 S ELLIS AVE,CHICAGO,IL 60637, USA. NR 42 TC 46 Z9 46 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 20 PY 1995 VL 442 IS 1 BP L25 EP L28 DI 10.1086/187807 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QM748 UT WOS:A1995QM74800007 ER PT J AU BLIVEN, LF BILLAT, V SOBIESKI, PW GUISSARD, AC BRANGER, H GIOVANANGELI, JP AF BLIVEN, LF BILLAT, V SOBIESKI, PW GUISSARD, AC BRANGER, H GIOVANANGELI, JP TI AN ASSESSMENT OF VEERING WIND EFFECTS ON SCATTEROMETRY FROM THE SEA-SURFACE SO INTERNATIONAL JOURNAL OF REMOTE SENSING LA English DT Article ID SCATTERING CALCULATIONS; OCEAN; SPECTRUM; STRESS; VECTOR AB To characterize scatterometer returns from the sea surface near meteorological fronts, we investigated microwave scattering from seas in which long waves are at oblique angles to short waves. We simulate the effects of veering winds on C- and K-u-band scatterometers by using models in which the short waves align with the wind friction velocity u*, but the long waves are at oblique angles to the u* direction. The analysis reveals two main effects due to the rotation of the long wave slope probability density distribution. Azimuthally averaged normalized radar cross-section a(0) decreases as the oblique angle increases. Additionally, two regimes exist. In the small angle regime, azimuthal scans of normalized radar cross-section sigma degrees exhibit features similar to the classic double-maxima pattern for non-veering wind conditions, but the axis of sigma degrees maxima is rotated toward the long-wave axis. In the large angle regime, more than two maxima are apparent in azimuthal scans. Therefore it may be inappropriate to use standard three term Fourier cosine models for some veering wind conditions. C1 UNIV SPACE RES ASSOC,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CATHOLIQUE LOUVAIN,DEPT ELECT,B-1348 LOUVAIN,BELGIUM. INST MECAN STAT TURBULENCE,MARSEILLE,FRANCE. RP BLIVEN, LF (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,WALLOPS ISL,VA 23337, USA. RI bliven, francis/E-1450-2012; Branger, Hubert/E-1879-2016 OI Branger, Hubert/0000-0002-9888-681X NR 34 TC 2 Z9 2 U1 0 U2 1 PU TAYLOR & FRANCIS LTD LONDON 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 20 PY 1995 VL 16 IS 5 BP 891 EP 903 PG 13 WC Remote Sensing; Imaging Science & Photographic Technology SC Remote Sensing; Imaging Science & Photographic Technology GA QR620 UT WOS:A1995QR62000009 ER PT J AU CIAIS, P TANS, PP WHITE, JWC TROLIER, M FRANCEY, RJ BERRY, JA RANDALL, DR SELLERS, PJ COLLATZ, JG SCHIMEL, DS AF CIAIS, P TANS, PP WHITE, JWC TROLIER, M FRANCEY, RJ BERRY, JA RANDALL, DR SELLERS, PJ COLLATZ, JG SCHIMEL, DS TI PARTITIONING OF OCEAN AND LAND UPTAKE OF CO2 AS INFERRED BY DELTA-C-13 MEASUREMENTS FROM THE NOAA CLIMATE MONITORING AND DIAGNOSTICS LABORATORY GLOBAL AIR SAMPLING NETWORK SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Review ID ATMOSPHERIC CARBON-DIOXIDE; ISOTOPE DISCRIMINATION; ARCTIC TUNDRA; LATITUDINAL DISTRIBUTION; BIOSPHERE EXCHANGE; TRANSPORT MODEL; BOUNDARY-LAYER; SINK; C-13; PHOTOSYNTHESIS AB Using delta(13)C measurements in atmospheric CO2 from a cooperative global air sampling network, we determined the partitioning of the net uptake of CO2 between ocean and land as a function of latitude and time. The majority of delta(13)C measurements were made at the Institute of Arctic and Alpine Research (INSTAAR) of the University of Colorado. The network included 40 sites in 1992 and constitutes the most extensive data set available. We perform an inverse deconvolution of both CO2 and delta(13)C observations, using a two-dimensional model of atmospheric transport. New features of the method include a detailed calculation of the isotopic disequilibrium of the terrestrial biosphere fi om global runs of the CENTURY soil model. Also, the discrimination against C-13 by plant photosynthesis, as a function of latitude and time, is calculated from global runs of the SiB biosphere model. Uncertainty due to the longitudinal structure of the data, which is not represented by the model, is studied through a bootstrap analysis by adding and omitting measurement sites. The resulting error estimates for our inferred sources and sinks are of the order of 1 GTC (1 GTC = 10(15) gC). Such error bars do not reflect potential systematic errors arising from our estimates of the isotopic disequilibria between the atmosphere and the oceans and biosphere, which are estimated in a separate sensitivity analysis. With respect to global totals for 1992 we found that 3.1 GTC of carbon dissolved into the ocean and that 1.5 GTC were sequestered by land ecosystems. Northern hemisphere ocean gyres north of 15 degrees N absorbed 2.7 GTC, The equatorial oceans between 10 degrees S and 10 degrees N were a net source to the atmosphere of 0.9 GTC. We obtained a sink of 1.6 GTC in southern ocean gyres south of 20 degrees S, although the deconvolution is poorly constrained by sparse data coverage at high southern latitudes. The seasonal uptake of CO2 in northern gyres appears to be correlated with a bloom of phytoplankton in surface waters. On land, northern temperate and boreal ecosystems between 35 degrees N and 65 degrees N were found to be a major sink of CO2 in 1992, as large as 3.5 GTC. Northern tropical ecosystems (equator-30 degrees N) appear to be a net source to the atmosphere of 2 GTC which could reflect biomass burning. A small sink, 0.3 GTC, was inferred for southern tropical ecosystems (30 degrees S-equator). C1 NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. CSIRO, DIV ATMOSPHER RES, MELBOURNE, VIC, AUSTRALIA. COLORADO STATE UNIV, DEPT ATMOSPHER SCI, FT COLLINS, CO 80521 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. UNIV COLORADO, INST ARCTIC & ALPINE RES, BOULDER, CO 80302 USA. CARNEGIE INST WASHINGTON, DEPT PLANT BIOL, STANFORD, CA 94305 USA. RI Berry, Joseph/B-8211-2009; White, James/A-7845-2009; collatz, george/D-5381-2012; Randall, David/E-6113-2011 OI Berry, Joseph/0000-0002-5849-6438; White, James/0000-0001-6041-4684; Randall, David/0000-0001-6935-4112 NR 98 TC 269 Z9 285 U1 3 U2 34 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 1995 VL 100 IS D3 BP 5051 EP 5070 DI 10.1029/94JD02847 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QN544 UT WOS:A1995QN54400003 ER PT J AU SCHOEBERL, MR LU, MZ ROSENFIELD, JE AF SCHOEBERL, MR LU, MZ ROSENFIELD, JE TI AN ANALYSIS OF THE ANTARCTIC HALOGEN OCCULTATION EXPERIMENT TRACE GAS OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID STRATOSPHERIC POLAR VORTEX; OZONE; TRANSPORT; TRENDS AB Analysis of the version 16 Halogen Occultation Experiment (HALOE) CH4 data shows that this long-lived trace gas is well correlated with potential vorticity (PV) computed from National Meteorological Center balanced winds. Analyzing late September and October 1992 data, we show that very low CH4 values are confined to the interior of a vortex edge defined by the maximum gradient in PV. The CH4 and HF time tendency is used to estimate the descent rate in the Antarctic vortex. After removing a component of the trend correlated with the HALOE sampling pattern, we compute the lower stratosphere vertical descent rates and net heating rates in the spring Antarctic vortex. Our computations of the spring Antarctic vortex heating rates give -0.5 to -0.1 K/day. Over the winter season, the overall lower stratospheric descent rate averages about 1.8-1.5 km/month. These computations are in line with radiative transfer estimates of the heating and descent rate. The HALOE data thus appear to be consistent with the picture of an isolated lower stratospheric Antarctic vortex. C1 UNIV CALIF IRVINE, DEPT EARTH SYST SCI, IRVINE, CA 92717 USA. APPL RES CORP, LANDOVER, MD 20375 USA. RP SCHOEBERL, MR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHER CHEM & DYNAM BRANCH, MAIL CODE 916, GREENBELT, MD 20771 USA. NR 26 TC 46 Z9 47 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 1995 VL 100 IS D3 BP 5159 EP 5172 DI 10.1029/94JD02749 PG 14 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QN544 UT WOS:A1995QN54400012 ER PT J AU CANZIANI, PO HOLTON, JR FISHBEIN, E FROIDEVAUX, L AF CANZIANI, PO HOLTON, JR FISHBEIN, E FROIDEVAUX, L TI EQUATORIAL KELVIN WAVE VARIABILITY DURING 1992 AND 1993 SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID SBUV OZONE DATA; SEMIANNUAL OSCILLATION; UPPER-STRATOSPHERE AB Temperature and ozone data from the Microwave Limb Sounder (MLS) instrument on UARS are used to analyze the variability of Kelvin wave activity during the first two years of the UARS mission. The analysis is carried out using the asynoptic mapping technique. Time frequency plots for zonal wavenumbers 1 and 2, at two heights representing the middle stratosphere and the stratopause, respectively, are used to analyze the temporal variability of the waves, and its possible relationship to the equatorial quasi-biennial oscillation (QBO) and semiannual oscillation(SAO), Kelvin wave activity reaches a maximum during the solstice seasons and almost disappears during the equinoxes, in agreement with previous studies. Eastward propagating variance is estimated for wave periods from 4 to 20 days, at all UARS pressure surfaces currently available for MLS. The semiannual modulation of variance is observed to extend down to the lower limits of the height ranges of the temperature and ozone retrievals. Furthermore, a superposed QBO modulation is detected up to the stratopause. Comparison between the variance in eastward propagating waves and the mean zonal wind shows a possible participation of kelvin waves in the forcing of the QBO. At the stratopause the role of Kelvin waves in forcing the SAO appears to be limited, in agreement with previous results. Between the 21-hPa and 4.6-hPa surfaces there appears to be a transition zone where there is no clear relationship between Kelvin wave activity and mean zonal flow acceleration. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP CANZIANI, PO (reprint author), UNIV WASHINGTON, DEPT ATMOSPHER SCI, AK-40, SEATTLE, WA 98195 USA. NR 22 TC 29 Z9 29 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 1995 VL 100 IS D3 BP 5193 EP 5202 DI 10.1029/94JD02330 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QN544 UT WOS:A1995QN54400014 ER PT J AU WEAVER, CJ DOUGLASS, AR ROOD, RB AF WEAVER, CJ DOUGLASS, AR ROOD, RB TI TRACER TRANSPORT FOR REALISTIC AIRCRAFT EMISSION SCENARIOS CALCULATED USING A 3-DIMENSIONAL MODEL SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID OZONE; STRATOSPHERE; CONSERVATION; SCHEME AB A three-dimensional transport model, which uses winds from a stratospheric data assimilation system, is used to study the transport of supersonic aircraft exhaust in the lower stratosphere. A passive tracer is continuously injected into the transport model. The tracer source distribution is based on realistic scenarios for the daily emission rate of reactive nitrogen species for all forecasted flight routes. Winds are from northern hemisphere winter/spring months for 1979 and 1989; there are minimal differences between the tracer integrations for the 2 years. During the integration, peak tracer mixing ratios in the flight corridors are compared with the zonal mean and found to be greater by a factor of 2 or less, This implies that the zonal mean assumption used in two dimensional models is reasonable during winter and spring. There is a preference for pollutant buildup in the heavily traveled North Pacific and North Atlantic flight corridors. Pollutant concentration in the corridors depends on the position of the Aleutian anticyclone and the northern hemisphere polar vortex edge. C1 APPL RES CORP, LANDOVER, MD 20785 USA. RP WEAVER, CJ (reprint author), NASA, GODDARD SPACE FLIGHT CTR, ATMOSPHERES LAB, CODE 916, GREENBELT, MD 20771 USA. RI Douglass, Anne/D-4655-2012; Rood, Richard/C-5611-2008 OI Rood, Richard/0000-0002-2310-4262 NR 18 TC 6 Z9 6 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 1995 VL 100 IS D3 BP 5203 EP 5214 DI 10.1029/94JD03320 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QN544 UT WOS:A1995QN54400015 ER PT J AU ZHAO, JX TOON, OB TURCO, RP AF ZHAO, JX TOON, OB TURCO, RP TI ORIGIN OF CONDENSATION NUCLEI IN THE SPRINGTIME POLAR STRATOSPHERE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID BALLOON-BORNE MEASUREMENTS; ANTARCTIC OBSERVATIONS; CHLORINE MONOXIDE; LOW ALTITUDES; EL-CHICHON; AEROSOL; VORTEX; PARTICLES; ERUPTION; ANALOGS AB An enhanced sulfate aerosol layer has been observed near 25 km accompanying springtime ozone depletion in the Antarctic stratosphere. We use a one-dimensional aerosol model that includes photochemistry, particle nucleation, condensational growth, coagulation, and sedimentation to study the origin of the layer. Annual cycles of sunlight, temperature, and ozone are incorporated into the model. Our results indicate that binary homogeneous nucleation leads to the formation of very small droplets of sulfuric acid and water under conditions of low temperature and production of H2SO4 following polar sunrise. Photodissociation of carbonyl sulfide (OCS)alone, however, cannot provide sufficient SO2 to create the observed condensation nuclei (CN) layer. When subsidence of SO2 from very high altitudes in the polar night vortex is incorporated into the model, the CN layer is reasonably reproduced. The model predictions, based on the subsidence in polar vortex, agree with in situ measurements of particle concentration, vertical distribution, and persistence during polar spring. C1 UNIV CALIF LOS ANGELES, DEPT ATMOSPHER SCI, LOS ANGELES, CA 90024 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 29 TC 31 Z9 31 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 1995 VL 100 IS D3 BP 5215 EP 5227 DI 10.1029/94JD03110 PG 13 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QN544 UT WOS:A1995QN54400016 ER PT J AU PILEWSKIE, P VALERO, FPJ AF PILEWSKIE, P VALERO, FPJ TI DIRECT OBSERVATIONS OF EXCESS SOLAR ABSORPTION BY CLOUDS SO SCIENCE LA English DT Article ID HAZE AB Aircraft measurements of solar flux in the cloudy tropical atmosphere reveal that solar absorption by clouds is anomalously large when compared to theoretical estimates. The ratio of cloud forcing at an altitude of 20 kilometers to that at the surface is 1.58 rather than 1.0, as predicted by models. These results were derived from a cloud radiation experiment in which identical instrumentation was deployed on coordinated stacked aircraft. These findings indicate a significant difference between measurements and theory and imply that the interaction between clouds and solar radiation is poorly understood. C1 UNIV CALIF SAN DIEGO,SCRIPPS INST OCEANOG,ATMOSPHER RES LAB,LA JOLLA,CA 92093. RP PILEWSKIE, P (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 7 TC 159 Z9 161 U1 1 U2 2 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAR 17 PY 1995 VL 267 IS 5204 BP 1626 EP 1629 DI 10.1126/science.267.5204.1626 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QM397 UT WOS:A1995QM39700030 PM 17808179 ER PT J AU BAUSCHLICHER, CW MAITRE, P AF BAUSCHLICHER, CW MAITRE, P TI STRUCTURE OF CO(H-2)N(+) CLUSTERS, FOR N=1-6 SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID GAUSSIAN-BASIS SETS; MOLECULAR CALCULATIONS; BINDING-ENERGIES; ROW ATOMS; IONS; EXCHANGE AB The geometries and H-2 binding energies have been determined for Co(H-2)(n)(+), for n = 1-6. The binding energies are in good agreement with experiment. The shape of the clusters is used to explain the pairwise decrease in the binding energies. The bonding in CoH2+ and Co(H-2)(2)(+) is very similar and is enhanced by sda hybridization. The next two H-2 molecules add to the side of Co(H-2)(2)(+), These two additional H-2 molecules cannot benefit from sd sigma hybridization and are less strongly bound. The addition of the fifth and sixth H-2 molecules eliminates sd sigma hybridization as a mechanism fur reducing Co-H-2 repulsion, This coupled with the smaller Co to H-2 sigma* donation results in another decrease in the binding energies. RP BAUSCHLICHER, CW (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Maitre, Philippe/C-1022-2013 OI Maitre, Philippe/0000-0003-2924-1054 NR 21 TC 48 Z9 48 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD MAR 16 PY 1995 VL 99 IS 11 BP 3444 EP 3447 DI 10.1021/j100011a007 PG 4 WC Chemistry, Physical SC Chemistry GA QN284 UT WOS:A1995QN28400007 ER PT J AU GRANA, AM LEE, TJ HEADGORDON, M AF GRANA, AM LEE, TJ HEADGORDON, M TI AB-INITIO CALCULATIONS OF SINGLET AND TRIPLET EXCITED-STATES OF CHLORINE NITRATE AND NITRIC-ACID SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID ABSORPTION CROSS-SECTIONS; MOLECULAR-ORBITAL THEORY; EXCITATION-ENERGIES; MICROWAVE-SPECTRUM; QUANTUM-CHEMISTRY; METHYL NITRATE; 248 NM; PHOTOLYSIS; PHOTODISSOCIATION; ABINITIO AB Ab initio calculations of vertical excitations to singlet and triplet excited states of chlorine nitrate and nitric acid are reported, using the CIS, CIS(D), and CCSD methods. The effects of basis set composition and calculational methods are investigated. The nature of the electronic transitions are examined by decomposing the difference density into the sum of detachment and attachment densities. Counterparts for the three lowest singlet excited states of nitric acid survive relatively unperturbed in chlorine nitrate, while other low lying singlet states of chlorine nitrate appear to be directly dissociative in the CIO chromophore. These results suggest an assignment of the two main peaks in the experimental chlorine nitrate absorption spectrum. In addition, triplet vertical excitations and the lowest optimized triplet geometries of both molecules are studied. C1 UNIV CALIF BERKELEY, DEPT CHEM, BERKELEY, CA 94720 USA. UNIV CALIF BERKELEY, LAWRENCE BERKELEY LAB, DIV CHEM SCI, BERKELEY, CA 94720 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV SANTIAGO, DEPT QUIM FIS, E-15706 SANTIAGO, SPAIN. RI Lee, Timothy/K-2838-2012; Grana, Ana/K-6055-2014 OI Grana, Ana/0000-0002-0794-2215 NR 71 TC 44 Z9 44 U1 0 U2 5 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD MAR 16 PY 1995 VL 99 IS 11 BP 3493 EP 3502 DI 10.1021/j100011a015 PG 10 WC Chemistry, Physical SC Chemistry GA QN284 UT WOS:A1995QN28400015 ER PT J AU HARRIS, AW AF HARRIS, AW TI SPACE SCIENCE - DESTRUCTIVE DEBRIS SO NATURE LA English DT Editorial Material RP HARRIS, AW (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,MS 183-501,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 9 TC 1 Z9 1 U1 0 U2 3 PU MACMILLAN MAGAZINES LTD PI LONDON PA 4 LITTLE ESSEX STREET, LONDON, ENGLAND WC2R 3LF SN 0028-0836 J9 NATURE JI Nature PD MAR 16 PY 1995 VL 374 IS 6519 BP 212 EP 213 DI 10.1038/374212a0 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QM387 UT WOS:A1995QM38700024 PM 7885438 ER PT J AU TSURUTANI, BT GONZALEZ, WD AF TSURUTANI, BT GONZALEZ, WD TI THE EFFICIENCY OF VISCOUS INTERACTION BETWEEN THE SOLAR-WIND AND THE MAGNETOSPHERE DURING INTENSE NORTHWARD IMF EVENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOPAUSE BOUNDARY-LAYER; MAGNETIC STORMS; DIFFUSION-PROCESSES; CONVECTION AB We examined 11 cases when the interplanetary magnetic field (IMF) was intensely northward (> 10 nT) for long durations of time (> 3 hours), to quantitatively determine an upper limit on the efficiency of solar wind energy injection into the magnetosphere. We have specifically selected these large BN events to minimize the effects of magnetic reconnection. Many of these cases occurred during intervals of high-speed streams associated with coronal mass ejections when viscous interaction effects might be at a maximum. It is found that the typical efficiency of solar wind energy injection into the magnetosphere is 1.0 x 10(-3) to 4.0 x 10(-3), 100 to 30 times less efficient than during periods of intense southward IMFs. Other energy sinks not included in these numbers are discussed. Estimates of their magnitudes are provided. C1 INST PESQUISAS ESPACIAIS,S JOSE CAMPOS,BRAZIL. RP TSURUTANI, BT (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 27 TC 61 Z9 63 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 MAR 15 PY 1995 VL 22 IS 6 BP 663 EP 666 DI 10.1029/95GL00205 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QN566 UT WOS:A1995QN56600001 ER PT J AU PULKKINEN, TI BAKER, DN WALKER, RJ RAEDER, J ASHOURABDALLA, M AF PULKKINEN, TI BAKER, DN WALKER, RJ RAEDER, J ASHOURABDALLA, M TI COMPARISON OF EMPIRICAL MAGNETIC-FIELD MODELS AND GLOBAL MHD SIMULATIONS - THE NEAR-TAIL CURRENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CURRENT SHEET; MAGNETOTAIL AB The tail currents predicted by empirical magnetic field models and global MHD simulations are compared. It is shown that the near-Earth currents obtained from the MHD simulations are much weaker than the currents predicted by the Tsyganenko models, primarily because the ring current is not properly represented in the simulations. On the other hand, in the mid-tail and distant tail the lobe field strength predicted by the simulations is comparable to what is observed at about 50R(E) distance, significantly larger than the very low lobe field values predicted by the Tsyganenko models at that distance. Ways to improve these complementary approaches to model the actual magnetospheric configuration are discussed. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV CALIF LOS ANGELES,INST GEOPHYS & PLANETARY PHYS,LOS ANGELES,CA 90024. RP PULKKINEN, TI (reprint author), FINNISH METEOROL INST,POB 503,SF-00101 HELSINKI,FINLAND. RI Pulkkinen, Tuija/D-8403-2012 OI Pulkkinen, Tuija/0000-0002-6317-381X NR 11 TC 14 Z9 14 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 15 PY 1995 VL 22 IS 6 BP 675 EP 678 DI 10.1029/95GL00540 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QN566 UT WOS:A1995QN56600004 ER PT J AU CARR, ES HARWOOD, RS MOTE, PW PECKHAM, GE SUTTIE, RA LAHOZ, WA ONEILL, A FROIDEVAUX, L JARNOT, RF READ, WG WATERS, JW SWINBANK, R AF CARR, ES HARWOOD, RS MOTE, PW PECKHAM, GE SUTTIE, RA LAHOZ, WA ONEILL, A FROIDEVAUX, L JARNOT, RF READ, WG WATERS, JW SWINBANK, R TI TROPICAL STRATOSPHERIC WATER-VAPOR MEASURED BY THE MICROWAVE LIMB SOUNDER (MLS) SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID CIRCULATION; AIR AB The lower stratospheric variability of equatorial water vapor, measured by the Microwave Limb Sounder (MLS), follows an annual cycle modulated by the quasi-biennial oscillation. At levels higher in the stratosphere, water vapor measurements exhibit a semiannual oscillatory signal with the largest amplitudes at 2.2 and 1hPa. Zonal-mean cross sections of MLS water vapour are consistent with previous satellite measurements from the LIMS and SAGE II instruments in that they show water vapor increasing upwards and pole-wards from a well defined minimum in the tropics. The minimum values vary in height between the retrieved 46 and 22hPa pressure levels. C1 HERIOT WATT UNIV,DEPT PHYS,EDINBURGH,MIDLOTHIAN,SCOTLAND. UNIV READING,DEPT METEOROL,READING,BERKS,ENGLAND. CALTECH,JET PROP LAB,PASADENA,CA. METEOROL OFF,DIV CR,BRACKNELL RB12 2SZ,BERKS,ENGLAND. RP CARR, ES (reprint author), UNIV EDINBURGH,DEPT METEOROL,EDINBURGH EH9 3JZ,MIDLOTHIAN,SCOTLAND. NR 20 TC 17 Z9 18 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 MAR 15 PY 1995 VL 22 IS 6 BP 691 EP 694 DI 10.1029/95GL00626 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QN566 UT WOS:A1995QN56600008 ER PT J AU AHUMADA, AJ ROHALY, AM WATSON, AB AF AHUMADA, AJ ROHALY, AM WATSON, AB TI IMAGE DISCRIMINATION MODELS PREDICT OBJECT DETECTION IN NATURAL BACKGROUNDS SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. USA,RES LAB,ABERDEEN PROVING GROUND,MD 21010. NR 2 TC 4 Z9 4 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQUARE, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1995 VL 36 IS 4 BP S439 EP S439 PG 1 WC Ophthalmology SC Ophthalmology GA QM915 UT WOS:A1995QM91502008 ER PT J AU BEUTTER, BR STONE, LS AF BEUTTER, BR STONE, LS TI DIRECTION OF PERCEIVED MOTION AND EYE-MOVEMENTS SHOW SIMILAR BIASES FOR ASYMMETRICALLY WINDOWED MOVING PLAIDS SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE 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 LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQUARE, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1995 VL 36 IS 4 BP S206 EP S206 PG 1 WC Ophthalmology SC Ophthalmology GA QM915 UT WOS:A1995QM91500947 ER PT J AU HECHT, H KAISER, MK AIKEN, W AF HECHT, H KAISER, MK AIKEN, W TI EXTRACTING DEPTH FROM MOTION PARALLAX IN REAL-WORLD AND SYNTHETIC DISPLAYS SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF SANTA CRUZ,SANTA CRUZ,CA 95064. RI Hecht, Heiko/H-3106-2011 NR 0 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQUARE, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1995 VL 36 IS 4 BP S359 EP S359 PG 1 WC Ophthalmology SC Ophthalmology GA QM915 UT WOS:A1995QM91501685 ER PT J AU MCDERMOTT, J BROSMAN, M THACH, AB LAMBERT FRAMBACH, DA AF MCDERMOTT, J BROSMAN, M THACH, AB LAMBERT FRAMBACH, DA TI A SYSTEM TO MEASURE FIXATION STABILITY WITH A SCANNING LASER OPHTHALMOSCOPE SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 UNIV SO CALIF,DOHENY EYE INST,LOS ANGELES,CA 90089. NASA,JET PROP LAB,PASADENA,CA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQUARE, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1995 VL 36 IS 4 BP S238 EP S238 PG 1 WC Ophthalmology SC Ophthalmology GA QM915 UT WOS:A1995QM91501078 ER PT J AU MULLIGAN, JB BEUTTER, BR STEVENSON, SB AF MULLIGAN, JB BEUTTER, BR STEVENSON, SB TI REFLEXIVE OKN IS BIASED LIKE PERCEPTION SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF BERKELEY,SCH OPTOMETRY,BERKELEY,CA 94720. NR 0 TC 0 Z9 0 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQUARE, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1995 VL 36 IS 4 BP S205 EP S205 PG 1 WC Ophthalmology SC Ophthalmology GA QM915 UT WOS:A1995QM91500945 ER PT J AU VERGHESE, P STONE, LS AF VERGHESE, P STONE, LS TI SPATIAL FACTORS IN THE INTEGRATION OF SPEED INFORMATION 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 SQUARE, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1995 VL 36 IS 4 BP S635 EP S635 PG 1 WC Ophthalmology SC Ophthalmology GA QM915 UT WOS:A1995QM91502904 ER PT J AU WATSON, AB SOLOMON, JA AF WATSON, AB SOLOMON, JA TI CONTRAST GAIN-CONTROL MODEL FITS MASKING DATA SO INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NR 0 TC 1 Z9 1 U1 0 U2 0 PU LIPPINCOTT-RAVEN PUBL PI PHILADELPHIA PA 227 EAST WASHINGTON SQUARE, PHILADELPHIA, PA 19106 SN 0146-0404 J9 INVEST OPHTH VIS SCI JI Invest. Ophthalmol. Vis. Sci. PD MAR 15 PY 1995 VL 36 IS 4 BP S438 EP S438 PG 1 WC Ophthalmology SC Ophthalmology GA QM915 UT WOS:A1995QM91502003 ER PT J AU GUSTAFSSON, B OLSSON, P AF GUSTAFSSON, B OLSSON, P TI 4TH-ORDER DIFFERENCE-METHODS FOR HYPERBOLIC IBVPS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID SCHEMES AB In this paper we consider fourth-order difference approximations of initial-boundary value problems for hyperbolic partial differential equations. We use the method of lines approach with both explicit and compact implicit difference operators in space. The explicit operator satisfies an energy estimate leading to strict stability. For the implicit operator we develop boundary conditions and give a complete proof of strong stability using the Laplace transform technique. We also present numerical experiments for the linear advection equation and Burgers' equation with discontinuities in the solution or in its derivative. The first equation is used for modeling contact discontinuities in fluid dynamics; the second one is used for modeling shocks and rarefaction waves. The time discretization is done with a third-order Runge-Kutta TVD method. For solutions with discontinuities in the solution itself we add a filter based on second-order viscosity. In case of the non-linear Burgers' equation we use a flux splitting technique that results in an energy estimate for certain difference approximations, in which case also an entropy condition is fulfilled. In particular we shall demonstrate that the unsplit conservative form produces a non-physical shock instead of the physically correct rarefaction wave. In the numerical experiments we compare our fourth-order methods with a standard second-order one and with a third-order TVD method. The results show that the fourth-order methods are the only ones that give good results for all the considered test problems. (C) 1995 Academic Press, Inc. RP GUSTAFSSON, B (reprint author), NASA,AMES RES CTR,RIACS,MAIL STOP T20G-5,MOFFETT FIELD,CA 94035, USA. NR 17 TC 26 Z9 26 U1 1 U2 5 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAR 15 PY 1995 VL 117 IS 2 BP 300 EP 317 DI 10.1006/jcph.1995.1068 PG 18 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA QN843 UT WOS:A1995QN84300012 ER PT J AU HAKKINEN, S AF HAKKINEN, S TI SIMULATED INTERANNUAL VARIABILITY OF THE GREENLAND SEA DEEP-WATER FORMATION AND ITS CONNECTION TO SURFACE FORCING SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID ICE-OCEAN SYSTEM; MODEL; CONVECTION; CIRCULATION; HEAT AB A fully prognostic Arctic ice-ocean model is used to study the interannual variability of deepwater formation in the Greenland Sea gyre based on the simulations for the Arctic ice-ocean system for the period 1955 and 1960-1985. The model uses monthly climatology for thermodynamic forcing components (such as air temperature and cloudiness), together with constant annual net precipitation and river runoff. The daily wind forcing is derived from analyzed sea level air pressures from the National Center for Atmospheric Research. In summary, the model shows that the occurrence of deep convection in the Greenland Sea gyre is controlled by the extensive Fram Strait ice export and/or local wind conditions in the Greenland Sea. In the latter case the weakening of the local wind curl allows the Polar Front to move eastward. The movement of the Polar Front causes adverse ice conditions, often together with much larger than normal ice export from the Arctic, such as in 1968, which can block convection in the gyre. The density difference between upper and lower layers is investigated as an indication of water mass formation through convection, occurring as strong diffusion in the model. The model-simulated density difference between the average top 100 m and deep levels reveals that the period 1960-1985 had only a few distinct years with weak stratification, and, especially, the model predicts no deep convection since the mid-1970s. The common factor for the years of the weakest stratification is extreme wintertime wind events. Deep convection is also evident as a decrease of the model-predicted heat content of the upper 2000 m which can, to a high degree, be explained by local heat loss. The salt content changes in the Greenland gyre are independent of the heat content changes and are determined by the advection of fresh or salty anomalies, either from the Arctic or from the frontal movement. The model indicates that the surface salinity flux favors freshening, even in wintertime, so that brine rejection is less important in buoyancy loss than heat loss in leading to deep convection. The model shows that the system has a memory; deep convection in one year will precondition the following year. RP HAKKINEN, S (reprint author), NASA,GODDARD SPACE FLIGHT CTR,HYDROSPHER PROC LAB,OCEANS & ICE BRANCH,CODE 971,GREENBELT,MD 20771, USA. RI Hakkinen, Sirpa/E-1461-2012 NR 29 TC 33 Z9 33 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 1995 VL 100 IS C3 BP 4761 EP 4770 DI 10.1029/94JC01900 PG 10 WC Oceanography SC Oceanography GA QN009 UT WOS:A1995QN00900038 ER PT J AU GENT, T TUCKER, D AF GENT, T TUCKER, D TI LIFETIME PREDICTIONS OF A GLASS-CERAMIC WITH MACHINED FLAWS SO JOURNAL OF MATERIALS SCIENCE LA English DT Article ID DYNAMIC FATIGUE; STRESSES AB A dynamic fatigue study was performed on a Li2O-Al2O3-SiO2 glass ceramic to assess its susceptibility to delayed failure and to compare the results with those from a previous study. Fracture mechanics techniques were used to analyse the results for the purpose of making lifetime predictions. The material strength and lifetime was seen to increase due to the removal of residual stress through grinding and polishing. Influence on time-to-failure is addressed for the case with and without residual stress present. RP GENT, T (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812, USA. NR 17 TC 1 Z9 1 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 MAR 15 PY 1995 VL 30 IS 6 BP 1535 EP 1538 DI 10.1007/BF00375260 PG 4 WC Materials Science, Multidisciplinary SC Materials Science GA QQ205 UT WOS:A1995QQ20500023 ER PT J AU BANFIELD, D INGERSOLL, AP KEPPENNE, CL AF BANFIELD, D INGERSOLL, AP KEPPENNE, CL TI A STEADY-STATE KALMAN FILTER FOR ASSIMILATING DATA FROM A SINGLE POLAR ORBITING SATELLITE SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Article ID ATMOSPHERIC DATA ASSIMILATION; STATISTICAL-INTERPOLATION; GENERAL-CIRCULATION; MARTIAN ATMOSPHERE; ERROR COVARIANCES; ANALYSIS SYSTEM; MODEL-ERROR AB A steady-state scheme for data assimilation in the context of a single, short period (relative to a day), sun-synchronous, polar-orbiting satellite is examined. If the satellite takes observations continuously, the gains, which are the weights for blending observations and predictions together, are: steady in time. For a linear system forced by random noise, the optimal steady-state gains (Wiener gains) are equivalent to those of a Kalman filter. Computing the Kalman gains increases the computational cost of the model by a large factor, but computing the Wiener gains does not. The latter are computed by iteration using prior estimates of the gains to assimilate simulated observations of one run of the model, termed ''truth,'' into another run termed ''prediction.'' At each stage, the prediction errors form the basis for the next estimate of the gains. Steady state is achieved after three or four iterations. Further simplification is achieved by making the gains depend on longitudinal distance from the observation point, not on absolute longitude. For a single-layer primitive equation model, the scheme works well even if only the mass field is observed but not the velocity field. Although the scheme was developed for Mars Observer, it should be applicable to data retrieved from Earth atmosphere satellites, for example, UARS. C1 CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125. CALTECH,JET PROP LAB,PASADENA,CA. OI Banfield, Don/0000-0003-2664-0164 NR 25 TC 15 Z9 15 U1 0 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 MAR 15 PY 1995 VL 52 IS 6 BP 737 EP 753 PG 17 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QP834 UT WOS:A1995QP83400007 ER PT J AU BOZZOLO, G IBANEZMEIER, R FERRANTE, J AF BOZZOLO, G IBANEZMEIER, R FERRANTE, J TI GROWTH OF AU ON NI(110) - A SEMIEMPIRICAL MODELING OF SURFACE ALLOY PHASES SO PHYSICAL REVIEW B LA English DT Article ID UNIVERSAL FEATURES; BINARY-ALLOYS; METALS; SEGREGATION; PARAMETERS; DEFECTS C1 WSA INC,PALO ALTO,CA 94301. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP BOZZOLO, G (reprint author), ANALEX CORP,3001 AEROSPACE PKWY,BROOKPARK,OH 44142, USA. NR 23 TC 22 Z9 22 U1 1 U2 2 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD MAR 15 PY 1995 VL 51 IS 11 BP 7207 EP 7216 DI 10.1103/PhysRevB.51.7207 PG 10 WC Physics, Condensed Matter SC Physics GA QP774 UT WOS:A1995QP77400052 ER PT J AU HALICIOGLU, T AF HALICIOGLU, T TI COMPARATIVE-STUDY ON ENERGY-RELATED AND STRUCTURE-RELATED PROPERTIES FOR THE (100) SURFACE OF BETA-SIC SO PHYSICAL REVIEW B LA English DT Article ID CUBIC SILICON-CARBIDE; BETA-SIC(100) SURFACE; CARBON; ENERGETICS; RECONSTRUCTION; POTENTIALS; PHASES C1 NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035. NR 27 TC 15 Z9 15 U1 0 U2 1 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1098-0121 J9 PHYS REV B JI Phys. Rev. B PD MAR 15 PY 1995 VL 51 IS 11 BP 7217 EP 7223 DI 10.1103/PhysRevB.51.7217 PG 7 WC Physics, Condensed Matter SC Physics GA QP774 UT WOS:A1995QP77400053 ER PT J AU CRAMER, JG FORWARD, RL MORRIS, MS VISSER, M BENFORD, G LANDIS, GA AF CRAMER, JG FORWARD, RL MORRIS, MS VISSER, M BENFORD, G LANDIS, GA TI NATURAL WORMHOLES AS GRAVITATIONAL LENSES SO PHYSICAL REVIEW D LA English DT Note ID TRAVERSABLE WORMHOLES; ENERGY CONDITION; TIME MACHINES; SPACETIME; STRINGS C1 FORWARD LTD,MALIBU,CA 90265. BUTLER UNIV,DEPT PHYS & ASTRON,INDIANAPOLIS,IN 46208. WASHINGTON UNIV,DEPT PHYS,ST LOUIS,MO 63130. UNIV CALIF IRVINE,DEPT PHYS,IRVINE,CA 92717. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CRAMER, JG (reprint author), UNIV WASHINGTON,DEPT PHYS FM15,SEATTLE,WA 98195, USA. OI Visser, Matt/0000-0003-1088-6485 NR 17 TC 93 Z9 93 U1 1 U2 3 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 1995 VL 51 IS 6 BP 3117 EP 3120 DI 10.1103/PhysRevD.51.3117 PG 4 WC Astronomy & Astrophysics; Physics, Particles & Fields SC Astronomy & Astrophysics; Physics GA QP747 UT WOS:A1995QP74700057 ER PT J AU SOUZA, KA BLACK, SD WASSERSUG, RJ AF SOUZA, KA BLACK, SD WASSERSUG, RJ TI AMPHIBIAN DEVELOPMENT IN THE VIRTUAL ABSENCE OF GRAVITY SO PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA LA English DT Article DE EMBRYONIC AXIS; MORPHOGENESIS; SWIMMING BEHAVIOR ID XENOPUS-LAEVIS; EMBRYOS; LARVAE AB To test whether gravity is required for normal amphibian development, Xenopus laevis females were induced to ovulate aboard the orbiting Space Shuttle. Eggs were fertilized in vitro, and although early embryonic stages showed some abnormalities, the embryos were able to regulate and produce nearly normal larvae. These results demonstrate that a vertebrate can ovulate in the virtual absence of gravity and that the eggs can develop to a free-living stage. C1 REED COLL,DEPT BIOL,PORTLAND,OR 97202. DALHOUSIE UNIV,FAC MED,DEPT ANAT & NEUROBIOL,HALIFAX,NS B3H 4H7,CANADA. RP SOUZA, KA (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 20 TC 59 Z9 63 U1 1 U2 2 PU NATL ACAD SCIENCES PI WASHINGTON PA 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 SN 0027-8424 J9 P NATL ACAD SCI USA JI Proc. Natl. Acad. Sci. U. S. A. PD MAR 14 PY 1995 VL 92 IS 6 BP 1975 EP 1978 DI 10.1073/pnas.92.6.1975 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QM408 UT WOS:A1995QM40800039 PM 7892210 ER PT J AU CONTOPOULOS, J KAZANAS, D AF CONTOPOULOS, J KAZANAS, D TI RELATIVISTIC HADRONS AND THE ORIGIN OF RELATIVISTIC OUTFLOWS IN ACTIVE GALACTIC NUCLEI SO ASTROPHYSICAL JOURNAL LA English DT Article DE ELEMENTARY PARTICLES; GALAXIES- ACTIVE; GALAXIES- JETS ID RADIO-SOURCES; GAMMA-RAYS; ACCRETION DISKS; JETS; NEUTRONS; INJECTION; RADIATION; PARTICLES; TRANSPORT; QUASARS AB We examine the hydrodynamic origin of relativistic outflows in active galactic nuclei (AGN). Specifically, we propose that the presence of a population of relativistic hadrons in the AGN ''central engine'' and the associated neutron production suffices to produce outflows which under rather general conditions could be relativistic. The main such condition is that the size of the neutron production region be larger than the neutron flight path c tau(n) similar or equal to 3 x 10(13) cm. This condition guarantees that the mean energy per particle in the proton fluid, resulting from the decay of the neutrons outside their production region, be greater than the proton rest mass. The expansion of this fluid can then lead naturally to a relativistic outflow by conversion of its internal energy to directed motion. We follow the development of such flows by solving the mass, energy as well as the kinetic equation for the proton gas in steady state, taking into account the source terms due to the decay of relativistic neutrons and adiabatic losses due to expansion. This process allows one to compute accurately the adiabatic index of the expanding gas, and in conjunction with Bernoulli's equation the detailed evolution of the bulk Lorentz factor. We further examine the role of large-scale magnetic fields in confining these outflows to produce the jets observed at larger scales. RP CONTOPOULOS, J (reprint author), NASA, GODDARD SPACE FLIGHT CTR, HIGH ENERGY ASTROPHYS LAB, GREENBELT, MD 20771 USA. NR 37 TC 13 Z9 13 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 1995 VL 441 IS 2 BP 521 EP 532 DI 10.1086/175379 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QK140 UT WOS:A1995QK14000010 ER PT J AU CALLANAN, PJ GARCIA, MR MCCLINTOCK, JE ZHAO, P REMILLARD, RA BAILYN, CD OROSZ, JA HARMON, BA PACIESAS, WS AF CALLANAN, PJ GARCIA, MR MCCLINTOCK, JE ZHAO, P REMILLARD, RA BAILYN, CD OROSZ, JA HARMON, BA PACIESAS, WS TI OBSERVATIONS OF THE X-RAY NOVA GRO JO422+32 .1. OUTBURST AND THE DECAY TO QUIESCENCE SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCRETION; ACCRETION DISKS; NOVAE; CATACLYSMIC VARIABLES; STARS, INDIVIDUAL (GRO JO422 + 32); X-RAYS, STARS ID BLACK-HOLE; TRANSIENTS; DISCOVERY; BINARY; MUSCAE; MODEL AB We present optical photometry and spectroscopy and BATSE observations of the X-ray nova GRO J0422+32, obtained during outburst and its subsequent decay to quiescence. Although the X-ray and optical properties of GRO J0422+32 are broadly similar to those of other X-ray novae, it is unique in several respects. The unusually protracted decay to quiescence of the optical light curve has been punctuated by at least two minioutbursts of similar to 4 mag. The BATSE and optical outbursts are each separated by similar to 120 days. We find that the optical luminosity of GRO J0422+32 during the primary outburst is dominated by reprocessing of E > 10 keV X-rays. In contrast, the optical minioutbursts are most likely generated by an intrinsically bright disk rather than X-ray reprocessing: they do not appear to have any X-ray counterparts. Extremely broad (up to 6000 km s(-1) FWZI) absorption lines have also been observed during both primary outbursts and minioutbursts. During the second minioutburst, H alpha and H beta emission was observed superposed on redshifted absorption features. We find that the interoutburst light curve of GRO J0422+32 may be inconsistent with an accretion disk instability as the origin of the minioutbursts. Finally, a transient 5.1/10.2 hr modulation, which may be related to the orbital period, has been observed during roughly half of our observations. However, confirmation of the orbital period must await observations in quiescence. C1 MIT,CTR SPACE RES,CAMBRIDGE,MA 02139. YALE UNIV,DEPT ASTRON,NEW HAVEN,CT 06511. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. UNIV ALABAMA,DEPT PHYS,HUNTSVILLE,AL 35899. RP CALLANAN, PJ (reprint author), CTR ASTROPHYS,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. NR 41 TC 53 Z9 53 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 10 PY 1995 VL 441 IS 2 BP 786 EP 799 DI 10.1086/175402 PN 1 PG 14 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QK140 UT WOS:A1995QK14000033 ER PT J AU DUNCAN, RA WHITE, SM LIM, J NELSON, GJ DRAKE, SA KUNDU, MR AF DUNCAN, RA WHITE, SM LIM, J NELSON, GJ DRAKE, SA KUNDU, MR TI INTENSE RADIO OUTBURST FROM THE SUPERMASSIVE STAR ETA-CARINAE SO ASTROPHYSICAL JOURNAL LA English DT Article DE CIRCUMSTELLAR MATTER; H II REGIONS; RADIO LINES, STARS; STARS, ACTIVITY STARS, INDIVIDUAL (ETA CARINAE); SUPERGIANTS AB On five occasions between 1999 June 29 and 1994 May 3, we have used the Australia Telescope Compact Array to image eta Carinae at a wavelength of 3 cm and a resolution of 1''. These observations have revealed remarkable activity. Since 1992 June, the total flux density has increase from 0.8 to 2.2 Jy, and the original single compact source has grown to a complex of sources spread over an area of about 16 arcsec(2) (Fig. 1). Strong hydrogen recombination-line spectral emission has appeared at the site of the strongest of these new sources. This recombination emission has the largest spectral width ever observed from a star, +/-250 km s(-1) and reveals gas with turbulent velocities as great as 250 km s(-1) approaching us at an average velocity of about 200 km s-(1). We believe that this radio outburst has been caused by a more than threefold increase of ultraviolet luminosity, and consequent ionization of previously neutral gas clouds. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. CALTECH,SOLAR ASTRON 264-33,PASADENA,CA 91125. ACAD SINICA,INST ASTRON & ASTROPHYS,TAIPEI 115,TAIWAN. AUSTRALIA TELESCOPE NATL FACIL,PAUL WILD OBSERV,NARRABRI,NSW 2390,AUSTRALIA. NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. RP DUNCAN, RA (reprint author), AUSTRALIA TELESCOPE NATL FACIL,POB 76,EPPING,NSW 2121,AUSTRALIA. NR 31 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 10 PY 1995 VL 441 IS 2 BP L73 EP & DI 10.1086/187793 PN 2 PG 0 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QK142 UT WOS:A1995QK14200006 ER PT J AU MUKHERJEE, R BERTSCH, DL DINGUS, BL KANBACH, G KNIFFEN, DA SREEKUMAR, P THOMPSON, DJ AF MUKHERJEE, R BERTSCH, DL DINGUS, BL KANBACH, G KNIFFEN, DA SREEKUMAR, P THOMPSON, DJ TI ON THE NATURE OF THE UNIDENTIFIED EGRET SOURCES - ARE THEY GEMINGA-LIKE PULSARS SO ASTROPHYSICAL JOURNAL LA English DT Article DE PULSARS, GENERAL; PULSARS, INDIVIDUAL (GEMINGA); GAMMA RAYS, OBSERVATIONS ID GAMMA-RAY SOURCES; TELESCOPE; CATALOG AB Observations with the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma Ray Observatory show more than 30 unidentified gamma-ray sources concentrated along the Galactic plane. Based on their spatial distribution, the typical distances of the sources are found to be between 1.2 and 6 kpc. Luminosity estimates made using the estimated distances of the sources and their observed gamma-ray fluxes lie in the range (0.7-16.7) x 10(35) ergs s(-1). These values, on the average, appear to be higher than the luminosities of the gamma-ray pulsars observed by EGRET. The luminosity estimates indicate that the low-latitude unidentified EGRET sources cannot be explained as a group of older, low-luminosity pulsars like Geminga, although the high-latitude sources may be candidates. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC. MAX PLANCK INST EXTRATERR PHYS,D-85748 GARCHING,GERMANY. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. RP MUKHERJEE, R (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 662,GREENBELT,MD 20771, USA. RI Thompson, David/D-2939-2012 OI Thompson, David/0000-0001-5217-9135 NR 23 TC 32 Z9 32 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 1995 VL 441 IS 2 BP L61 EP L64 DI 10.1086/187790 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QK142 UT WOS:A1995QK14200003 ER PT J AU FERRANDO, A LANE, H STUART, C WOLFE, R AF FERRANDO, A LANE, H STUART, C WOLFE, R TI PROTEIN-TURNOVER DURING 14 DAYS OF BED REST SO FASEB JOURNAL LA English DT Meeting Abstract C1 UNIV TEXAS,MED BRANCH,GALVESTON,TX 77550. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NR 0 TC 1 Z9 1 U1 1 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 10 PY 1995 VL 9 IS 4 BP A746 EP A746 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40600703 ER PT J AU FORTNEY, SM BENNETT, BS LEE, SMC GILBERT, JH BAMMAN, MM YELLE, JM CROUCH, JD MCCARTHY, JP AF FORTNEY, SM BENNETT, BS LEE, SMC GILBERT, JH BAMMAN, MM YELLE, JM CROUCH, JD MCCARTHY, JP TI A 12-WEEK RESISTANCE EXERCISE (REX) PROGRAM DOES NOT IMPROVE ORTHOSTATIC FUNCTION SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. KRUG LIFE SCI INC,HOUSTON,TX 77058. NR 0 TC 0 Z9 0 U1 0 U2 1 PU FEDERATION AMER SOC EXP BIOL PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 SN 0892-6638 J9 FASEB J JI Faseb J. PD MAR 10 PY 1995 VL 9 IS 4 BP A873 EP A873 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40601447 ER PT J AU GREENLEAF, JE BERNAUER, EM ERTL, AC AF GREENLEAF, JE BERNAUER, EM ERTL, AC TI SUBMAXIMAL EXERCISE (V)OVER-CIRCLE-O-2 AND (Q)OVER-CIRCLE DURING 30-DAY 6-DEGREES HEAD-DOWN BED REST WITH ISOTONIC AND ISOKINETIC EXERCISE TRAINING SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,DIV LIFE SCI,MOFFETT FIELD,CA 94035. UNIV CALIF DAVIS,HUMAN PERFORMANCE LAB,DAVIS,CA 95616. 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 10 PY 1995 VL 9 IS 4 BP A873 EP A873 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40601445 ER PT J AU HINGHOFERSZALKAY, HG GREENLEAF, JE AF HINGHOFERSZALKAY, HG GREENLEAF, JE TI CAPILLARY-PRESSURE BALANCE WITH REPEATED HEAD-UP TILT IN HUMANS SO FASEB JOURNAL LA English DT Meeting Abstract C1 AUSTRIAN SOC AEROSP MED,INST ADAPTAT & SPACE FLIGHT PHYSIOL,A-8010 GRAZ,AUSTRIA. NASA,AMES RES CTR,HUMAN ENVIRONM PHYSIOL LAB,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 10 PY 1995 VL 9 IS 4 BP A631 EP A631 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40600039 ER PT J AU LEE, SMC BENNETT, BS HARGENS, AR WATENPAUGH, DE BALLARD, RE MURTHY, G FORD, S FORTNEY, SM AF LEE, SMC BENNETT, BS HARGENS, AR WATENPAUGH, DE BALLARD, RE MURTHY, G FORD, S FORTNEY, SM TI SUPINE EXERCISE WITH LOWER-BODY NEGATIVE-PRESSURE (LBNP) MAINTAINS UPRIGHT EXERCISE RESPONSES AFTER BED REST SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. NASA,AMES RES CTR,MOFFETT FIELD,CA. UNIV TEXAS,MED BRANCH,GALVESTON,TX. 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 10 PY 1995 VL 9 IS 4 BP A873 EP A873 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40601448 ER PT J AU MOORE, AD LEE, SMC FORTNEY, SM GREENISEN, MC AF MOORE, AD LEE, SMC FORTNEY, SM GREENISEN, MC TI IN-FLIGHT MAXIMAL EXERCISE AS A COUNTERMEASURE TO EXERCISE TACHYCARDIA AFTER SPACE-FLIGHT SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. KRUG LIFE SCI INC,HOUSTON,TX. 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 10 PY 1995 VL 9 IS 4 BP A873 EP A873 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40601444 ER PT J AU NAVIDI, M HARPER, J EVANS, J FUNG, P WOLINSKY, I ARNAUD, SB AF NAVIDI, M HARPER, J EVANS, J FUNG, P WOLINSKY, I ARNAUD, SB TI CALCIUM AND PHOSPHORUS BALANCES IN YOUNG-RATS EXPOSED TO A SPACE-FLIGHT MODEL SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV HOUSTON,HOUSTON,TX 77204. NR 2 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 10 PY 1995 VL 9 IS 4 BP A874 EP A874 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40601452 ER PT J AU SCHALTENBRAND, W LANE, H COBURN, S TOWNSEND, D CONN, P SMITH, SM LEBLANC, A AF SCHALTENBRAND, W LANE, H COBURN, S TOWNSEND, D CONN, P SMITH, SM LEBLANC, A TI INCREASED PYRIDOXIC ACID EXCRETION DURING BED REST SO FASEB JOURNAL LA English DT Meeting Abstract C1 FT WAYNE STATE DEV CTR,FT WAYNE,IN 46835. NASA,LYNDON B JOHNSON SPACE CTR,BIOMED OPERAT & RES BRANCH,HOUSTON,TX 77058. INDIANA UNIV PURDUE UNIV,FT WAYNE,IN 46805. BAYLOR COLL MED,HOUSTON,TX 77030. 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 10 PY 1995 VL 9 IS 4 BP A986 EP A986 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40602102 ER PT J AU WADE, CE MOORE, AL MOREYHOLTON, E AF WADE, CE MOORE, AL MOREYHOLTON, E TI INCREASED RENAL SOLUTE EXCRETION IN RATS FOLLOWING SPACE-FLIGHT SO FASEB JOURNAL 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 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 10 PY 1995 VL 9 IS 4 BP A874 EP A874 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40601453 ER PT J AU WILLIAMS, WJ STUART, CA FORTNEY, SM PIETRZYK, RA CHEN, YM WHITSON, PA AF WILLIAMS, WJ STUART, CA FORTNEY, SM PIETRZYK, RA CHEN, YM WHITSON, PA TI CHANGES IN FLUID ELECTROLYTE CONTROLLING HORMONES DURING HEAD-DOWN BED REST - EFFECT OF DIETARY-SODIUM SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. KRUG LIFE SCI,HOUSTON,TX 77058. UNIV TEXAS,MED BRANCH,GALVESTON,TX 77555. 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 10 PY 1995 VL 9 IS 4 BP A874 EP A874 PN 2 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QM406 UT WOS:A1995QM40601449 ER PT J AU ABDULAZIZ, M AUPING, JV MEADOR, MA AF ABDULAZIZ, M AUPING, JV MEADOR, MA TI SYNTHESIS OF SUBSTITUTED 2,3,5,6-TETRAARYLBENZO[1,2-B-5,4-B']DIFURANS SO JOURNAL OF ORGANIC CHEMISTRY LA English DT Article ID PHOTOCYCLIZATION REACTIONS; KETONES; 1,5-BIRADICALS AB A series of substituted 2,3,5,6-tetraarylbenzo[1,2-b:5,4-b']difurans 1 was synthesized. This synthesis is based upon the photocyclization of 2,5-dibenzoylresorcinol dibenzyl ethers to the corresponding tetrahydrobenzo[1,2-b:5,4-b']difurans. Treatment of the photoproducts with methanesulfonyl chloride in pyridine afforded 1 in overall yields ranging from 30-72%. A number of these compounds have high fluorescence quantum yields (phi(f) = 0.76-0.90), and their fluorescence spectra exhibit large solvatochromic shifts. These compounds may be suitable for use as fluorescent probes. C1 NASA, LEWIS RES CTR, DIV MAT, POLYMERS BRANCH, CLEVELAND, OH 44135 USA. CASE WESTERN RESERVE UNIV, DEPT CHEM, CLEVELAND, OH 44106 USA. NR 27 TC 34 Z9 34 U1 0 U2 2 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3263 J9 J ORG CHEM JI J. Org. Chem. PD MAR 10 PY 1995 VL 60 IS 5 BP 1303 EP 1308 DI 10.1021/jo00110a038 PG 6 WC Chemistry, Organic SC Chemistry GA QL605 UT WOS:A1995QL60500038 ER PT J AU SMITH, SM MORUKOV, B LARINA, I NILLEN, J LANE, HW AF SMITH, SM MORUKOV, B LARINA, I NILLEN, J LANE, HW TI PYRIDINIUM CROSS-LINK EXCRETION DURING SPACE-FLIGHT SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,LYNDON B JOHNSON SPACE CTR,KRUG,HOUSTON,TX 77058. MOSCOW BIOMED PROBLEMS INST,MOSCOW,RUSSIA. 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 9 PY 1995 VL 9 IS 3 BP 163 EP 163 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QL987 UT WOS:A1995QL98700977 ER PT J AU CONKLIN, D LILLYWHITE, H OLSON, K BALLARD, R HARGENS, A AF CONKLIN, D LILLYWHITE, H OLSON, K BALLARD, R HARGENS, A TI BLOOD-VESSEL REACTIVITY IN A SEMIARBOREAL SNAKE SO FASEB JOURNAL 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 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 9 PY 1995 VL 9 IS 3 BP A354 EP A354 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QL987 UT WOS:A1995QL98702074 ER PT J AU CONLEY MEYER, MR BLOOMBERG, J FEEBACK, D DUDLEY, G AF CONLEY MEYER, MR BLOOMBERG, J FEEBACK, D DUDLEY, G TI MRI ANALYSIS OF HUMAN NECK MUSCLE FUNCTION SO FASEB JOURNAL LA English DT Meeting Abstract C1 UNIV GEORGIA,ATHENS,GA 30605. MICHIGAN STATE UNIV,E LANSING,MI 48824. 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 9 PY 1995 VL 9 IS 3 BP A360 EP A360 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QL987 UT WOS:A1995QL98702113 ER PT J AU GRINDELAND, RE ROY, RR EDGERTON, VR BIGBEE, AJ GOSSELINK, KL AF GRINDELAND, RE ROY, RR EDGERTON, VR BIGBEE, AJ GOSSELINK, KL TI GROWTH-HORMONE SECRETION BY EXERCISED RATS SO FASEB JOURNAL LA English DT Meeting Abstract C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. UNIV CALIF LOS ANGELES,LOS ANGELES,CA 90024. NR 0 TC 1 Z9 1 U1 1 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 9 PY 1995 VL 9 IS 3 BP A363 EP A363 PN 1 PG 1 WC Biochemistry & Molecular Biology; Biology; Cell Biology SC Biochemistry & Molecular Biology; Life Sciences & Biomedicine - Other Topics; Cell Biology GA QL987 UT WOS:A1995QL98702129 ER PT J AU HUDGINS, DM ALLAMANDOLA, LJ AF HUDGINS, DM ALLAMANDOLA, LJ TI INFRARED-SPECTROSCOPY OF MATRIX-ISOLATED POLYCYCLIC AROMATIC HYDROCARBON CATIONS .2. THE MEMBERS OF THE THERMODYNAMICALLY MOST FAVORABLE SERIES THROUGH CORONENE SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID ABSORPTION-SPECTROSCOPY; CONDENSED AROMATICS; EMISSION FEATURES; SPECTRA; NAPHTHALENE; BANDS; TEMPERATURES; IONIZATION; MOLECULES; PRESSURE AB Gaseous, ionized polycyclic aromatic hydrocarbons (PAHs) are thought to be responsible for a very common family of interstellar infrared emission bands. Here the near- and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene:phenanthrene, pyrene, benzo[e]pyrene, benzo[ghi]perylene, and coronene, are presented to test this hypothesis. For those molecules that have been studied previously (pyrene, pyrene-d(10), and coronene), band positions and relative intensities are in agreement. In all of these cases we report additional features. Absolute integrated absorbance values are given for the phenanthrene, perdeuteriophenanthrene, pyrene, benzo[ghi]perylene, and coronene cations. With the exception of coronene, the cation bands corresponding to the CC modes are typically 2-5 times more intense than those of the CH out-of-plane bending vibrations. For the cations, the CC stretching and CH in-plane bending modes give rise to bands that are an order of magnitude stronger than those of the neutral species, and the CH out-of-plane bends produce bands that are 5-20 times weaker than those of the neutral species. This behavior is similar to that found in most other PAH cations studied to date. The astronomical implications of these PAH cation spectra are also discussed. C1 NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. NR 48 TC 166 Z9 166 U1 3 U2 23 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD MAR 9 PY 1995 VL 99 IS 10 BP 3033 EP 3046 DI 10.1021/j100010a011 PG 14 WC Chemistry, Physical SC Chemistry GA QL680 UT WOS:A1995QL68000011 PM 11538457 ER PT J AU TINGAY, SJ JAUNCEY, DL PRESTON, RA REYNOLDS, JE MELER, DL MURPHY, DW TZIOUMIS, AK MCKAY, DJ KESTEVEN, MJ LOVELL, JEJ CAMPBELLWILSON, D ELLINGSEN, SP GOUGH, R HUNSTEAD, RW JONES, DL MCCULLOCH, PM MIGENES, V QUICK, J SINCLAIR, MW SMITS, D AF TINGAY, SJ JAUNCEY, DL PRESTON, RA REYNOLDS, JE MELER, DL MURPHY, DW TZIOUMIS, AK MCKAY, DJ KESTEVEN, MJ LOVELL, JEJ CAMPBELLWILSON, D ELLINGSEN, SP GOUGH, R HUNSTEAD, RW JONES, DL MCCULLOCH, PM MIGENES, V QUICK, J SINCLAIR, MW SMITS, D TI RELATIVISTIC MOTION IN A NEARBY BRIGHT X-RAY SOURCE SO NATURE LA English DT Article ID RESOLUTION AB THE recent discovery(1) of radio components apparently moving away from a Galactic source of transient X-ray emission faster than the speed of light (superluminal motion) has identified a low-energy Galactic counterpart to quasars. Here we report high-resolution radio observations of a second Galactic superluminal radio source GRO J1655-40, which was detected as an X-ray transient(2) on 27 July 1994. Our radio images reveal two components moving away from each other at an angular speed of 65 +/- 5 mas d(-1), corresponding to superluminal motion at the estimated distance of 3-5 kpc. The 12-day delay between the X-ray and radio outbursts suggests that the ejection of material at relativistic speeds occurs during a stable phase of accretion onto a black hole, which follows an unstable phase with a high accretion rate, C1 JET PROPULS LAB,PASADENA,CA 91109. AUSTRALIA TELESCOPE NATL FACIL,EPPING,NSW 2121,AUSTRALIA. UNIV TASMANIA,HOBART,TAS 7001,AUSTRALIA. HARTEBEESTHOEK RADIO ASTRON OBSERV,HARTEBEESTHEOK 1740,SOUTH AFRICA. UNIV SYDNEY,SYDNEY,NSW 2006,AUSTRALIA. RP TINGAY, SJ (reprint author), MT STROMLO & SIDING SPRING OBSERV,CANBERRA,ACT 2611,AUSTRALIA. RI Tingay, Steven/B-5271-2013; Ellingsen, Simon/J-7754-2014; Migenes, Victor/F-3157-2015 OI Ellingsen, Simon/0000-0002-1363-5457; Migenes, Victor/0000-0002-7990-2191 NR 13 TC 234 Z9 234 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 9 PY 1995 VL 374 IS 6518 BP 141 EP 143 DI 10.1038/374141a0 PG 3 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QL397 UT WOS:A1995QL39700051 ER PT J AU WALCH, SP AF WALCH, SP TI A NEW POTENTIAL-ENERGY SURFACE FOR N+O-2 - IS THERE AN NOO MINIMUM SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID CONFIGURATION-INTERACTION CALCULATIONS RP WALCH, SP (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MS 230-3,MOFFETT FIELD,CA 94035, USA. NR 6 TC 9 Z9 9 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD MAR 8 PY 1995 VL 102 IS 10 BP 4189 EP 4192 DI 10.1063/1.469466 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QL734 UT WOS:A1995QL73400032 ER PT J AU BARCLAY, VJ DATEO, CE HAMILTON, IP AF BARCLAY, VJ DATEO, CE HAMILTON, IP TI AB-INITIO VIBRATIONAL LEVELS FOR HO2 AND VIBRATIONAL SPLITTINGS FOR HYDROGEN-ATOM TRANSFER (VOL 101, PG 6766, 1994) SO JOURNAL OF CHEMICAL PHYSICS LA English DT Correction, Addition C1 UNIV TORONTO,DEPT CHEM,TORONTO,ON M5S 1A1,CANADA. NASA,AMES RES CTR,INST THERMOSCI,MOFFETT FIELD,CA 94035. WILFRID LAURIER UNIV,DEPT CHEM,WATERLOO,ON N2L 3C5,CANADA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD MAR 8 PY 1995 VL 102 IS 10 BP 4308 EP 4308 DI 10.1063/1.469478 PG 1 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QL734 UT WOS:A1995QL73400044 ER PT J AU TRAN, K HANNINGLEE, MA BISWAS, A STIEGMAN, AE SCOTT, GW AF TRAN, K HANNINGLEE, MA BISWAS, A STIEGMAN, AE SCOTT, GW TI ELECTRONIC-STRUCTURE OF DISCRETE PSEUDOTETRAHEDRAL OXOVANADIUM CENTERS DISPERSED IN A SILICA XEROGEL MATRIX - IMPLICATIONS FOR CATALYSIS AND PHOTOCATALYSIS SO JOURNAL OF THE AMERICAN CHEMICAL SOCIETY LA English DT Article ID SUPPORTED VANADIUM-OXIDE; LASER RAMAN-SPECTROSCOPY; PHOTO-LUMINESCENCE; SPECTRA; STATE; REDUCTION; MOLECULES; V2O5; VO43; SIO2 AB The electronic structure of pseudotetrahedral oxovanadium groups (-O3V=O) dispersed in a silica xerogel matrix, is determined on the basis of a spectroscopic investigation. From this investigation it was found that the highest occupied molecular orbital of this species is a nonbonding a(2) symmetry orbital localized on the basal plane ligands. The first excited state is assigned to an E symmetry triplet resulting from a one-electron promotion from this a(2) nonbonding orbital to an e symmetry antibonding orbital of the terminal V=O group. On the basis of this orbital description, the long-lived, vibronically structured emission at 549 nm is assigned to a (3)E --> (1)A(1) transition from the e antibonding orbital back down to the a nonbonding orbital [(a(2))(1)(e*)(1)] --> [(a(2))(2)(e*)]. The vibronic progression in the emission band at 977 +/- 10 cm(-1), previously assigned to the terminal V=O stretch, is reassigned to a V-O stretch involving the basal plane oxygens, consistent with the orbital assignment. Contrary to previous descriptions, excitations involving pi --> pi* type transitions localized on the terminal V=O group Lie at higher energy. The first well-resolved singlet band at 290 nm is of A(1) symmetry and has a resolved vibronic progression which corresponds to the terminal V=O stretch. This band is assigned to a (1)A(1) --> (1)A(1) transition involving a [(e)(4)(a(2))(2)(e*)] --> [(e)(3)(a(2))(2)(e*)(1)] one-electron promotion which can qualitatively be described as a ''pi-pi*'' V=O transition. The electronic structure of the pseudotetrahedral oxovanadium group established in this study differs dramatically from the conventionally accepted model which localizes the ground and first excited state on the terminal V=O group. This new description, however, is completely consistent with observed photochemical processes and, unlike the previous model, provides a coherent explanation of how factors such as the nature of the substrate directly affect the oxovanadium center. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UNIV CALIF RIVERSIDE, DEPT CHEM, RIVERSIDE, CA 92521 USA. NR 44 TC 65 Z9 67 U1 0 U2 10 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0002-7863 J9 J AM CHEM SOC JI J. Am. Chem. Soc. PD MAR 8 PY 1995 VL 117 IS 9 BP 2618 EP 2626 DI 10.1021/ja00114a026 PG 9 WC Chemistry, Multidisciplinary SC Chemistry GA QL789 UT WOS:A1995QL78900026 ER PT J AU MIELKE, SL TAWA, GJ TRUHLAR, DG SCHWENKE, DW AF MIELKE, SL TAWA, GJ TRUHLAR, DG SCHWENKE, DW TI QUANTUM PHOTOCHEMISTRY - ACCURATE QUANTUM SCATTERING CALCULATIONS FOR AN ELECTRONICALLY NONADIABATIC REACTION SO CHEMICAL PHYSICS LETTERS LA English DT Article ID MOLECULAR-COLLISIONS; ENERGY-TRANSFER; PROBABILITIES; TRANSITIONS; STATES; H+ AB We present converged quantum mechanical scattering calculations of reaction and quenching probabilities for a problem involving an electronically excited product. The calculations correspond to two coupled potential energy surfaces representing the ground and first. electronically excited state of H2Br. Results are presented for H + HBr --> H-2 + Br and H + Br --> H-2 + Br-*, where an asterisk denotes electronic excitation, and the lack of an asterisk denotes the electronic ground state. The calculations are carried out by linear algebraic variational methods with a multi-arrangement diabatic basis. These benchmark calculations are used to test a one-dimensional model, which is found to be quantitatively unreliable. C1 UNIV MINNESOTA, CHEM PHYS PROGRAM, MINNEAPOLIS, MN 55455 USA. UNIV MINNESOTA, INST SUPERCOMP, MINNEAPOLIS, MN 55455 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RP MIELKE, SL (reprint author), UNIV MINNESOTA, DEPT CHEM, 207 PLEASANT ST SE, MINNEAPOLIS, MN 55455 USA. RI Mielke, Steven/B-7533-2008; schwenke, david/I-3564-2013; Truhlar, Donald/G-7076-2015 OI Mielke, Steven/0000-0002-1938-7503; Truhlar, Donald/0000-0002-7742-7294 NR 35 TC 49 Z9 49 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD MAR 3 PY 1995 VL 234 IS 1-3 BP 57 EP 63 DI 10.1016/0009-2614(94)01515-W PG 7 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QJ742 UT WOS:A1995QJ74200011 ER PT J AU ORTON, G AHEARN, M BAINES, K DEMING, D DOWLING, T GOGUEN, J GRIFFITH, C HAMMEL, H HOFFMANN, W HUNTEN, D JEWITT, D KOSTIUK, T MILLER, S NOLL, K ZAHNLE, K ACHILLEOS, N DAYAL, A DEUTSCH, L ESPENAK, F ESTERLE, P FRIEDSON, J FAST, K HARRINGTON, J HORA, J JOSEPH, R KELLY, D KNACKE, R LACY, J LISSE, C RAYNER, J SPRAGUE, A SHURE, M WELLS, K YANAMANDRAFISHER, P ZIPOY, D BJORAKER, G BUHL, D GOLISCH, W GRIEP, D KAMINSKI, C ARDEN, C CHAIKIN, A GOLDSTEIN, J GILMORE, D FAZIO, G KANAMORI, T LAM, H LIVENGOOD, T MACLOW, MM MARLEY, M MOMARY, T ROBERTSON, D ROMANI, P SPITALE, J SYKES, M TENNYSON, J WELLNITZ, D YING, SW AF ORTON, G AHEARN, M BAINES, K DEMING, D DOWLING, T GOGUEN, J GRIFFITH, C HAMMEL, H HOFFMANN, W HUNTEN, D JEWITT, D KOSTIUK, T MILLER, S NOLL, K ZAHNLE, K ACHILLEOS, N DAYAL, A DEUTSCH, L ESPENAK, F ESTERLE, P FRIEDSON, J FAST, K HARRINGTON, J HORA, J JOSEPH, R KELLY, D KNACKE, R LACY, J LISSE, C RAYNER, J SPRAGUE, A SHURE, M WELLS, K YANAMANDRAFISHER, P ZIPOY, D BJORAKER, G BUHL, D GOLISCH, W GRIEP, D KAMINSKI, C ARDEN, C CHAIKIN, A GOLDSTEIN, J GILMORE, D FAZIO, G KANAMORI, T LAM, H LIVENGOOD, T MACLOW, MM MARLEY, M MOMARY, T ROBERTSON, D ROMANI, P SPITALE, J SYKES, M TENNYSON, J WELLNITZ, D YING, SW TI COLLISION OF COMET SHOEMAKER-LEVY-9 WITH JUPITER OBSERVED BY THE NASA INFRARED TELESCOPE FACILITY SO SCIENCE LA English DT Article ID ETHANE AB The National Aeronautics and Space Administration (NASA) Infrared Telescope Facility was used to investigate the collision of comet Shoemaker-Levy 9 with Jupiter from 12 July to 7 August 1994. Strong thermal infrared emission lasting several minutes was observed after the impacts of fragments C, G, and R. All impacts warmed the stratosphere and some the troposphere up to several degrees. The abundance of stratospheric ammonia increased by more than 50 times. Impact-related particles extended up to a level where the atmospheric pressure measured several millibars. The north polar near-infrared aurora brightened by nearly a factor of 5 a week after the impacts. C1 UNIV MARYLAND, DEPT ASTRON, COLLEGE PK, MD 20742 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. MIT, CAMBRIDGE, MA 02139 USA. NO ARIZONA UNIV, DEPT PHYS & ASTRON, FLAGSTAFF, AZ 86011 USA. UNIV ARIZONA, STEWARD OBSERV, TUCSON, AZ 85721 USA. UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. UNIV HAWAII, INST ASTRON, HONOLULU, HI 96822 USA. UCL, DEPT PHYS & ASTRON, LONDON WC1E 6BT, ENGLAND. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94053 USA. UNIV MASSACHUSETTS, FIVE COLL ASTRON DEPT, AMHERST, MA 01003 USA. UNIV TEXAS, DEPT ASTRON, AUSTIN, TX 78712 USA. PENN STATE UNIV, ERIE, PA 16563 USA. UNIV ST ANDREWS, DEPT PHYS, ST ANDREWS, FIFE, SCOTLAND. SMITHSONIAN INST, NATL AIR & SPACE MUSEUM, WASHINGTON, DC 20560 USA. SMITHSONIAN ASTROPHYS OBSERV, CAMBRIDGE, MA 02138 USA. STANFORD UNIV, DEPT MECH ENGN & DESIGN, STANFORD, CA 94305 USA. UNIV CHICAGO, DEPT ASTRON & ASTROPHYS, CHICAGO, IL 60637 USA. NEW MEXICO STATE UNIV, DEPT ASTRON, LAS CRUCES, NM 88003 USA. UNIV CALIF LOS ANGELES, LOS ANGELES, CA 90024 USA. UNIV LEICESTER, DEPT PHYS & ASTRON, LEICESTER LE1 7RH, LEICS, ENGLAND. CALTECH, PASADENA, CA 91126 USA. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED, LONDON SW7 2BZ, ENGLAND. RP ORTON, G (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Achilleos, Nicholas/C-1647-2008; Harrington, Joseph/E-6250-2011; Wellnitz, Dennis/B-4080-2012; Noll, Keith/C-8447-2012; Livengood, Timothy/C-8512-2012; Romani, Paul/D-2729-2012; Bjoraker, Gordon/D-5032-2012; Tennyson, Jonathan/I-2222-2012; Marley, Mark/I-4704-2013; Dowling, Timothy/J-4537-2013; Kostiuk, Theodor/A-3077-2014; Lisse, Carey/B-7772-2016 OI Hora, Joseph/0000-0002-5599-4650; Achilleos, Nicholas/0000-0002-5886-3509; Tennyson, Jonathan/0000-0002-4994-5238; Dowling, Timothy/0000-0002-7400-2274; Lisse, Carey/0000-0002-9548-1526 NR 28 TC 60 Z9 60 U1 0 U2 5 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD MAR 3 PY 1995 VL 267 IS 5202 BP 1277 EP 1282 DI 10.1126/science.7871423 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QK068 UT WOS:A1995QK06800028 PM 7871423 ER PT J AU WEAVER, HA AHEARN, MF ARPIGNY, C BOICE, DC FELDMAN, PD LARSON, SM LAMY, P LEVY, DH MARSDEN, BG MEECH, KJ NOLL, KS SCOTTI, JV SEKANINA, Z SHOEMAKER, CS SHOEMAKER, EM SMITH, TE STERN, SA STORRS, AD TRAUGER, JT YEOMANS, DK ZELLNER, B AF WEAVER, HA AHEARN, MF ARPIGNY, C BOICE, DC FELDMAN, PD LARSON, SM LAMY, P LEVY, DH MARSDEN, BG MEECH, KJ NOLL, KS SCOTTI, JV SEKANINA, Z SHOEMAKER, CS SHOEMAKER, EM SMITH, TE STERN, SA STORRS, AD TRAUGER, JT YEOMANS, DK ZELLNER, B TI THE HUBBLE-SPACE-TELESCOPE (HST) OBSERVING CAMPAIGN ON COMET SHOEMAKER-LEVY-9 SO SCIENCE LA English DT Article AB The Hubble Space Telescope made systematic observations of the split comet P/Shoemaker-Levy 9 (SL9) (P designates a periodic comet) starting in July 1993 and continuing through mid-July 1994 when the fragments plunged into Jupiter's atmosphere. Deconvolutions of Wide Field Planetary Camera images indicate that the diameters of some fragments may have been as large as similar to 2 to 4 kilometers, assuming a geometric albedo of 4 percent, but significantly smaller values (that is, <1 kilometer) cannot be ruled out. Most of the fragments (or nuclei) were embedded in circularly symmetric inner comae from July 1993 until late June 1994, implying that there was continuous, but weak, cometary activity. At least a few nuclei fragmented into separate, condensed objects well after the breakup of the SL9 parent body, which argues against the hypothesis that the SL9 fragments were swarms of debris with no dominant, central bodies. Spectroscopic observations taken on 14 July 1994 showed an outburst in magnesium ion emission that was followed closely by a threefold increase in continuum emission, which may have been caused by the electrostatic charging and subsequent explosion of dust as the comet passed from interplanetary space into the jovian magnetosphere. No OH emission was detected, but the derived upper limit on the H2O production rate of similar to 10(27) molecules per second does not necessarily imply that the object was water-poor. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. SW RES INST,DIV 15,SAN ANTONIO,TX 78228. JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. UNIV ARIZONA,LUNAR & PLANETARY LAB,TUCSON,AZ 85721. LAB ASTRON SPATIALE TRAVERSE SIPHON,F-13376 MARSEILLE 12,FRANCE. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822. JET PROPULS LAB,PASADENA,CA 91109. NO ARIZONA UNIV,DEPT PHYS & ASTRON,FLAGSTAFF,AZ 86011. US GEOL SURVEY,FLAGSTAFF,AZ 86001. SW RES INST,DIV 15,BOULDER EXTENS OFF,BOULDER,CO 80302. GEORGIA SO UNIV,DEPT PHYS,STATESBORO,GA 30460. RP WEAVER, HA (reprint author), SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218, USA. RI Noll, Keith/C-8447-2012; Weaver, Harold/D-9188-2016 NR 20 TC 69 Z9 69 U1 0 U2 4 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAR 3 PY 1995 VL 267 IS 5202 BP 1282 EP 1288 DI 10.1126/science.7871424 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QK068 UT WOS:A1995QK06800029 PM 7871424 ER PT J AU HAMMEL, HB BEEBE, RF INGERSOLL, AP ORTON, GS MILLS, JR SIMON, AA CHODAS, P CLARKE, JT DEJONG, E DOWLING, TE HARRINGTON, J HUBER, LF KARKOSCHKA, E SANTORI, CM TOIGO, A YEOMANS, D WEST, RA AF HAMMEL, HB BEEBE, RF INGERSOLL, AP ORTON, GS MILLS, JR SIMON, AA CHODAS, P CLARKE, JT DEJONG, E DOWLING, TE HARRINGTON, J HUBER, LF KARKOSCHKA, E SANTORI, CM TOIGO, A YEOMANS, D WEST, RA TI HST IMAGING OF ATMOSPHERIC PHENOMENA CREATED BY THE IMPACT OF COMET SHOEMAKER-LEVY-9 SO SCIENCE LA English DT Article ID GREAT RED SPOT; JUPITERS AB Hubble Space Telescope (HST) images reveal major atmospheric changes created by the collision of comet Shoemaker-Levy 9 with Jupiter. Plumes rose to 3000 kilometers with ejection velocities on the order of 10 kilometers second(-1); some plumes were visible in the shadow of Jupiter before rising into sunlight. During some impacts, the incoming bolide may have been detected. Impact times were on average about 8 minutes later than predicted. Atmospheric waves were seen with a wave front speed of 454 +/- 20 meters second(-1). The HST images reveal impact site evolution and record the overall change in Jupiter's appearance as a result of the bombardment. C1 MIT, DEPT EARTH ATMOSPHER & PLANETARY SCI, CAMBRIDGE, MA 02139 USA. CALTECH, DIV GEOL & PLANETARY SCI, PASADENA, CA 91125 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. UNIV MICHIGAN, DEPT ATMOSPHER & OCEAN SCI, ANN ARBOR, MI 48109 USA. UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. NEW MEXICO STATE UNIV, DEPT ASTRON, LAS CRUCES, NM 88003 USA. RP MIT, DEPT EARTH ATMOSPHER & PLANETARY SCI, CAMBRIDGE, MA 02139 USA. RI Santori, Charles/A-7314-2009; Harrington, Joseph/E-6250-2011; Clarke, John/C-8644-2013; Dowling, Timothy/J-4537-2013; Simon, Amy/C-8020-2012 OI Dowling, Timothy/0000-0002-7400-2274; Simon, Amy/0000-0003-4641-6186 NR 31 TC 151 Z9 155 U1 0 U2 11 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 3 PY 1995 VL 267 IS 5202 BP 1288 EP 1296 DI 10.1126/science.7871425 PG 9 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QK068 UT WOS:A1995QK06800030 PM 7871425 ER PT J AU WEST, RA KARKOSCHKA, E FRIEDSON, AJ SEYMOUR, M BAINES, KH HAMMEL, HB AF WEST, RA KARKOSCHKA, E FRIEDSON, AJ SEYMOUR, M BAINES, KH HAMMEL, HB TI IMPACT DEBRIS PARTICLES IN JUPITER STRATOSPHERE SO SCIENCE LA English DT Article ID OPTICAL-PROPERTIES; ICE; CIRCULATION; ULTRAVIOLET; CONSTANTS AB The aftermath of the impacts of periodic comet Shoemaker-Levy 9 on Jupiter was studied With the Wide Field Planetary Camera 2 on the Hubble Space Telescope. The impact debris particles may owe their dark brown color to organic material rich in sulfur and nitrogen. The total volume of aerosol 1 day after the last impact is equal to the volume of a sphere of radius 0.5 kilometer. In the optically thick core regions, the particle mean radius is between 0.15 and 0.3 micrometer, and the aerosol is spread over many scale heights, from approximately 1 millibar to 200 millibars of pressure or more. Particle coagulation can account for the evolution of particle radius and total optical depth during the month following the impacts. C1 UNIV ARIZONA, LUNAR & PLANETARY LAB, TUCSON, AZ 85721 USA. UCL, LONDON, ENGLAND. MIT, DEPT EARTH ATMOSPHER & PLANETARY SCI, CAMBRIDGE, MA 02139 USA. RP WEST, RA (reprint author), CALTECH, JET PROP LAB, DIV EARTH & SPACE SCI, PASADENA, CA 91109 USA. NR 26 TC 81 Z9 81 U1 1 U2 2 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD MAR 3 PY 1995 VL 267 IS 5202 BP 1296 EP 1301 DI 10.1126/science.7871426 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QK068 UT WOS:A1995QK06800031 PM 7871426 ER PT J AU CLARKE, JT PRANGE, R BALLESTER, GE TRAUGER, J EVANS, R REGO, D STAPELFELDT, K IP, W GERARD, JC HAMMEL, H BALLAV, M BENJAFFEL, L BERTAUX, JL CRISP, D EMERICH, C HARRIS, W HORANYI, M MILLER, S STORRS, A WEAVER, H AF CLARKE, JT PRANGE, R BALLESTER, GE TRAUGER, J EVANS, R REGO, D STAPELFELDT, K IP, W GERARD, JC HAMMEL, H BALLAV, M BENJAFFEL, L BERTAUX, JL CRISP, D EMERICH, C HARRIS, W HORANYI, M MILLER, S STORRS, A WEAVER, H TI HST FAR-ULTRAVIOLET IMAGING OF JUPITER DURING THE IMPACTS OF COMET SHOEMAKER-LEVY-9 SO SCIENCE LA English DT Article ID HUBBLE-SPACE-TELESCOPE; POLAR AURORA AB Hubble Space Telescope far-ultraviolet images of Jupiter during the Shoemaker-Levy 9 impacts show the impact regions darkening over the 2 to 3 hours after the impact, becoming darker and more extended than at longer wavelengths, which indicates that ultraviolet-absorbing gases or aerosols are more extended, more absorbing, and at higher altitudes than the absorbers of visible light, Transient auroral emissions were observed near the magnetic conjugate point of the K impact site just after that impact. The global auroral activity was fainter than average during the impacts, and a variable auroral emission feature was observed inside the southern auroral oval preceding the impacts of fragments Q1 and Q2. C1 UNIV PARIS 11, CNRS, INST ASTROPHYS SPATIALE, F-91405 ORSAY, FRANCE. CNRS, INST ASTROPHYS SPATIALE, F-75014 PARIS, FRANCE. JET PROPULS LAB, PASADENA, CA 91109 USA. MAX PLANCK INST AERON, D-37191 KATLENBURG DUHM, GERMANY. UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. MIT, CAMBRIDGE, MA 02139 USA. CNRS, SERV AERON, F-91371 VERRIERES LE BUISSON, FRANCE. UNIV COLORADO, ATMOSPHER & SPACE PHYS LAB, BOULDER, CO 80309 USA. UCL, DEPT PHYS & ASTRON, LONDON, ENGLAND. SPACE TELESCOPE SCI INST, BALTIMORE, MD 21218 USA. RP CLARKE, JT (reprint author), UNIV MICHIGAN, SPACE PHYS RES LAB, ANN ARBOR, MI 48109 USA. RI Stapelfeldt, Karl/D-2721-2012; Clarke, John/C-8644-2013; Weaver, Harold/D-9188-2016; OI Horanyi, Mihaly/0000-0002-5920-9226; GERARD, Jean-Claude/0000-0002-8565-8746 NR 37 TC 59 Z9 59 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 MAR 3 PY 1995 VL 267 IS 5202 BP 1302 EP 1307 DI 10.1126/science.7871427 PG 6 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QK068 UT WOS:A1995QK06800032 PM 7871427 ER PT J AU NOLL, KS MCGRATH, MA TRAFTON, LM ATREYA, SK CALDWELL, JJ WEAVER, HA YELLE, RV BARNET, C EDGINGTON, S AF NOLL, KS MCGRATH, MA TRAFTON, LM ATREYA, SK CALDWELL, JJ WEAVER, HA YELLE, RV BARNET, C EDGINGTON, S TI HST SPECTROSCOPIC OBSERVATIONS OF JUPITER AFTER THE COLLISION OF COMET SHOEMAKER-LEVY-9 SO SCIENCE LA English DT Article ID CROSS-SECTION MEASUREMENTS; CARBON-MONOXIDE; NM; REGION; SO2; S2 AB Ultraviolet spectra obtained with the Hubble Space Telescope identified at least 10 molecules and atoms in the perturbed stratosphere near the G impact site, most never before observed in Jupiter. The large mass of sulfur-containing material, more than 10(14) grams in S-2 alone, indicates that many of the sulfur-containing molecules S-2, CS2, CS, H2S, and S+ may be derived from a sulfur-bearing parent molecule native to Jupiter. If so, the fragment must have penetrated at least as deep as the predicted NH4SH cloud at a pressure of approximately 1 to 2 bars, Stratospheric NH3 was also observed, which is consistent with fragment penetration below the cloud tops. Approximately 10(7) grams of neutral and ionized metals were observed in emission, including Mg II, Mg I, Si I, Fe I, and Fe II. Oxygen-containing molecules were conspicuous by their absence; upper limits for SO2, SO, CO, SiO, and H2O are derived, C1 UNIV TEXAS,DEPT ASTRON,AUSTIN,TX 78712. UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. INST SPACE & TERR SCI,SPACE ASTROPHYS LAB,N YORK,ON M3J 3K1,CANADA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP NOLL, KS (reprint author), SPACE TELESCOPE SCI INST,3700 SAN MARTIN DR,BALTIMORE,MD 21218, USA. RI Barnet, Christopher/F-5573-2010; Noll, Keith/C-8447-2012; Weaver, Harold/D-9188-2016 NR 36 TC 90 Z9 90 U1 0 U2 7 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAR 3 PY 1995 VL 267 IS 5202 BP 1307 EP 1313 DI 10.1126/science.7871428 PG 7 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QK068 UT WOS:A1995QK06800033 PM 7871428 ER PT J AU MCGRATH, MA HALL, DT MATHESON, PL WEAVER, HA TRAUGER, JT SMITH, TE THOMAS, N GLADSTONE, R SCHNEIDER, NM HARRIS, WM LIVENGOOD, TA PRANGE, R FESTOU, MC AF MCGRATH, MA HALL, DT MATHESON, PL WEAVER, HA TRAUGER, JT SMITH, TE THOMAS, N GLADSTONE, R SCHNEIDER, NM HARRIS, WM LIVENGOOD, TA PRANGE, R FESTOU, MC TI RESPONSE OF THE IO-PLASMA TORUS TO COMET SHOEMAKER-LEVY-9 SO SCIENCE LA English DT Article AB Spectroscopic and imaging observations of the lo plasma torus were made in June and July 1994 in conjunction with the encounter of periodic comet Shoemaker-Levy 9 with Jupiter, Characteristic emissions from sulfur and oxygen ions showed a decline of about 30 percent in the extreme ultraviolet and an increase of about 40 percent in the far ultraviolet relative to preimpact observations. Changes in the extreme ultraviolet may be indicative of small changes in the torus electron temperature as a result of quenching of electrons by dust associated with the comet passage. However, no new emission features indicative of fragment dust within the torus were detected. The characteristic torus morphology seen in ground-based imaging was typical of that observed in the past. C1 JOHNS HOPKINS UNIV,DEPT PHYS & ASTRON,BALTIMORE,MD 21218. UNIV SO CALIF,DEPT AEROSP ENGN,LOS ANGELES,CA 90089. JET PROPULS LAB,PASADENA,CA 91109. MAX PLANCK INST AERON,W-3411 KATLENBURG DUHM,GERMANY. SW RES INST,SAN ANTONIO,TX 78238. UNIV COLORADO,ASTRON & SPACE PHYS LAB,BOULDER,CO 80309. UNIV MICHIGAN,SPACE PHYS RES LAB,ANN ARBOR,MI 48109. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. INST ASTROPHYS SPATIALE,ORSAY,FRANCE. OBSERV MIDI PYRENEES,NATL CTR SCI RES,F-31400 TOULOUSE,FRANCE. RP MCGRATH, MA (reprint author), SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218, USA. RI Livengood, Timothy/C-8512-2012; Weaver, Harold/D-9188-2016; OI SCHNEIDER, NICHOLAS/0000-0001-6720-5519 NR 17 TC 10 Z9 10 U1 0 U2 1 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAR 3 PY 1995 VL 267 IS 5202 BP 1313 EP 1317 DI 10.1126/science.7871429 PG 5 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QK068 UT WOS:A1995QK06800034 PM 7871429 ER PT J AU PRANGE, R ENGLE, IM CLARKE, JT DUNLOP, M BALLESTER, GE IP, WH MAURICE, S TRAUGER, J AF PRANGE, R ENGLE, IM CLARKE, JT DUNLOP, M BALLESTER, GE IP, WH MAURICE, S TRAUGER, J TI AURORAL SIGNATURE OF COMET SHOEMAKER-LEVY-9 IN THE JOVIAN MAGNETOSPHERE SO SCIENCE LA English DT Article AB The electrodynamic interaction of the dust and gas comae of comet Shoemaker-Levy 9 with the jovian magnetosphere was unique and different from the atmospheric effects. Early theoretical predictions of auroral-type processes on the comet magnetic field line and advanced modeling of the time-varying morphology of these lines allowed dedicated observations with the Hubble Space Telescope Wide Field Planetary Camera 2 and resulted in the detection of a bright auroral spot, In that respect, this observation of the surface signature of an externally triggered auroral process can be considered as a ''magnetospheric active experiment'' on Jupiter. C1 INST ASTROPHYS,PARIS,FRANCE. USN ACAD,DEPT PHYS,ANNAPOLIS,MD 21402. UNIV MICHIGAN,DEPT ATMOSPHER OCEAN & SPACE SCI,ANN ARBOR,MI 48109. UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,SPACE & ATMOSPHER PHYS GRP,LONDON SW7 2BZ,ENGLAND. MAX PLANCK INST AERON,D-37191 KATLENBURG DUHM,GERMANY. EUROPEAN SPACE AGCY,ESTEC,DEPT SPACE SCI,SO,2200 AG NOORDWIJK,NETHERLANDS. JET PROPULS LAB,PASADENA,CA 91109. RP PRANGE, R (reprint author), UNIV PARIS 11,CNRS,INST ASTROPHYS SPATIALE,F-91405 ORSAY,FRANCE. RI dunlop, malcolm/F-1347-2010; Clarke, John/C-8644-2013 NR 18 TC 14 Z9 14 U1 0 U2 2 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD MAR 3 PY 1995 VL 267 IS 5202 BP 1317 EP 1320 DI 10.1126/science.7871430 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QK068 UT WOS:A1995QK06800035 PM 7871430 ER PT J AU RAY, RD AF RAY, RD TI ALGORITHM-741 - LEAST-SQUARES SOLUTION OF A LINEAR, BORDERED, BLOCK-DIAGONAL SYSTEM OF EQUATIONS SO ACM TRANSACTIONS ON MATHEMATICAL SOFTWARE LA English DT Note DE BORDERED BLOCK-DIAGONAL EQUATIONS; LEAST-SQUARES SOLUTIONS; SPARSE SYSTEMS ID ALGEBRA SUBPROGRAMS; SET AB A package of Fortran subroutines is presented for the least-squares solution of a system of overdetermined, full-rank, linear equations with single-bordered block-diagonal structure. This structure allows for a natural sequential processing, one block diagonal at a time, so that large systems can be handled even on smaller machines. Orthogonal transformations in the form of Householder reflections are used to factor the system. The routines make heavy use of the Levels 1, 2, and 3 BLAS. RP RAY, RD (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 926,GREENBELT,MD 20771, USA. NR 14 TC 0 Z9 0 U1 0 U2 0 PU ASSOC COMPUTING MACHINERY PI NEW YORK PA 1515 BROADWAY, NEW YORK, NY 10036 SN 0098-3500 J9 ACM T MATH SOFTWARE JI ACM Trans. Math. Softw. PD MAR PY 1995 VL 21 IS 1 BP 20 EP 25 DI 10.1145/200979.200987 PG 6 WC Computer Science, Software Engineering; Mathematics, Applied SC Computer Science; Mathematics GA QW105 UT WOS:A1995QW10500003 ER PT J AU WESOKY, HL AF WESOKY, HL TI OZONE, SKIN-CANCER, AND THE SST SO AEROSPACE AMERICA LA English DT Letter RP WESOKY, HL (reprint author), NASA,OFF AERONAUT,WASHINGTON,DC 20546, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0740-722X J9 AEROSPACE AM JI Aerosp. Am. PD MAR PY 1995 VL 33 IS 3 BP 10 EP 10 PG 1 WC Engineering, Aerospace SC Engineering GA QK913 UT WOS:A1995QK91300005 ER PT J AU DAUGHTRY, CST MCMURTREY, JE CHAPPELLE, EW DULANEY, WP IRONS, JR SATTERWHITE, MB AF DAUGHTRY, CST MCMURTREY, JE CHAPPELLE, EW DULANEY, WP IRONS, JR SATTERWHITE, MB TI POTENTIAL FOR DISCRIMINATING CROP RESIDUES FROM SOIL BY REFLECTANCE AND FLUORESCENCE SO AGRONOMY JOURNAL LA English DT Article ID COVER AB Crop residues left in the field after harvest can be important in controlling soil erosion. Current methods for quantifying percent crop residue cover are tedious and somewhat subjective. There is a need for new methods to quantify residue cover that are rapid, accurate, and objective. We evaluated reflectance and fluorescence techniques for discriminating crop residues from a wide range of soils. Reflectance and fluorescence spectra of 37 agricultural soils (wet and dry) and of recently harvested and weathered corn (Zea mays L.), soybean [Glycine mar (L.) Mere], sorghum [Sorghum bicolor (L.) Moench], and wheat (Triticum aestivum L.) residues were measured in the lab. Reflectance factors in the visible or near-infrared wavelengths did not uniquely distinguish all soils from all crop residues. Crop residues may be brighter or darker than a given soil, depending on soil moisture and residue age. When illuminated with ultraviolet radiation, however, the crop residues fluoresced more than most of the soils. Fluorescence of crop residues was a broad-band phenomenon centered between 420 to 520 nm and induced by a relatively broad range of excitation wavelengths centered between 350 to 400 nm. More than 90% of the crop residues <2 yr old could be discriminated from 33 of 37 dry soils and 36 of 37 wet soils using fluorescence. The threshold for discrimination can be optimized for classification accuracy for each soil. Fluorescence techniques are less ambiguous than reflectance methods and are better suited for discriminating crop residues on soils. Furthermore, if properly implemented, fluorescence techniques can be used to quantify crop residue cover in the field. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. UNIV MARYLAND,DEPT GEOG,COLLEGE PK,MD 20742. USA,ENGINEER TOPOG LABS,FT BELVOIR,VA 22060. RP DAUGHTRY, CST (reprint author), USDA ARS,REMOTE SENSING RES LAB,BLDG 007 BARC W,10300 BALTIMORE AVE,BELTSVILLE,MD 20705, USA. RI Irons, James/D-8535-2012 NR 18 TC 38 Z9 40 U1 3 U2 5 PU AMER SOC AGRONOMY PI MADISON PA 677 S SEGOE RD, MADISON, WI 53711 SN 0002-1962 J9 AGRON J JI Agron. J. PD MAR-APR PY 1995 VL 87 IS 2 BP 165 EP 171 PG 7 WC Agronomy SC Agriculture GA QX030 UT WOS:A1995QX03000005 ER PT J AU HARDIN, JC POPE, DS AF HARDIN, JC POPE, DS TI SOUND GENERATION BY FLOW OVER A 2-DIMENSIONAL CAVITY SO AIAA JOURNAL LA English DT Article ID BOUNDARY-CONDITIONS AB Sound generated by how over a cavity at a Mach number of 0.1 and a Reynolds number based on cavity length of 5000 is calculated. The computation utilizes a two part technique where the time-dependent incompressible flow is first obtained and then a second calculation is performed for the compressible aspects of the flow. This second calculation utilizes a grid and numerical scheme designed for resolution of acoustic waves. The cavity flowfield is observed to oscillate quite regularly at the Strouhal number of 0.58 which produces an acoustic source of the same frequency. Time histories, spectra, and directivity of the sound radiation are computed. C1 LOCKHEED ENGN & SCI CO,DEPT ACOUST & DYNAM,HAMPTON,VA 23665. RP HARDIN, JC (reprint author), NASA,LANGLEY RES CTR,DIV ACOUST,HAMPTON,VA 23681, USA. NR 8 TC 44 Z9 51 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 MAR PY 1995 VL 33 IS 3 BP 407 EP 412 DI 10.2514/3.12592 PG 6 WC Engineering, Aerospace SC Engineering GA QQ967 UT WOS:A1995QQ96700003 ER PT J AU PONTON, MK SEINER, JM AF PONTON, MK SEINER, JM TI ACOUSTIC STUDY OF B-HELICAL MODE FOR CHOKED AXISYMMETRICAL NOZZLE SO AIAA JOURNAL LA English DT Article ID LAYERS AB An acoustic near-field study was performed for an axisymmetric conical convergent nozzle operating at a pressure ratio corresponding to a fully expanded Mach number of 1.3. The acoustic measurements were performed in the nozzle exit plane using multiple sensors arranged around the periphery of the nozzle. The acquired data were simultaneously digitized. The acoustic spatial characteristics, describing the large-stale structure associated with the preferred shear layer instability mode, were determined for the dominant B screech mode. The nozzle was fitted with a lip thickening device to determine the effect of this geometric variable on the spatial structure of the jet. For the thin-lipped configuration, the flapping structure of the B screech mode was found to precess in a time-dependent manner about the jet axis. Increasing of the nozzle exit lip thickness altered the spatial characteristics of this mode from a napping to a time-dependent napping or spinning. Using the autobicoherence spectrum, frequency dependencies were found to exist in the acoustic data of the thick-lipped configuration. These dependencies may be related to the nonlinearity of the jet and/or the time-dependent nature of the B mode spatial structure. RP PONTON, MK (reprint author), NASA,LANGLEY RES CTR,AEROACOUST BRANCH,HAMPTON,VA 23681, USA. NR 28 TC 15 Z9 15 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 1995 VL 33 IS 3 BP 413 EP 420 DI 10.2514/3.12402 PG 8 WC Engineering, Aerospace SC Engineering GA QQ967 UT WOS:A1995QQ96700004 ER PT J AU MAVRIPLIS, DJ AF MAVRIPLIS, DJ TI 3-DIMENSIONAL MULTIGRID REYNOLDS-AVERAGED NAVIER-STOKES SOLVER FOR UNSTRUCTURED MESHES SO AIAA JOURNAL LA English DT Article ID ADAPTIVE MESHES; EQUATIONS AB A three-dimensional unstructured mesh Reynolds-averaged Navier-Stokes solver is described. Turbulence is simulated using a single field-equation model. Computational overheads are minimized through the use of a single edge-based data structure, an efficient multigrid solution technique, and the use of multitasking on shared memory multiprocessors. The accuracy and efficiency of the code are evaluated by computing two-dimensional flows in three dimensions and comparing with results from a previously validated two-dimensional code that employs the same solution algorithm. The feasibility of computing three-dimensional turbulent flows on grids of several million points in less than 2 h of wall clock time is demonstrated. RP MAVRIPLIS, DJ (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681, USA. NR 17 TC 28 Z9 28 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 1995 VL 33 IS 3 BP 445 EP 453 DI 10.2514/3.12597 PG 9 WC Engineering, Aerospace SC Engineering GA QQ967 UT WOS:A1995QQ96700008 ER PT J AU DOGRA, VK MOSS, JN WILMOTH, RG TAYLOR, JC HASSAN, HA AF DOGRA, VK MOSS, JN WILMOTH, RG TAYLOR, JC HASSAN, HA TI EFFECTS OF CHEMISTRY ON BLUNT-BODY WAKE STRUCTURE SO AIAA JOURNAL LA English DT Article ID MODEL AB Results of a numerical study are presented for hypersonic low-density flow about a 70-deg blunt cone using direct simulation Monte Carlo (DSMC) and Navier-Stokes calculations. Particular emphasis is given to the effects of chemistry on the near-wake structure and on the surface quantities and the comparison of the DSMC results with the Navier-Stokes calculations. The flow conditions simulated are those experienced by a space vehicle at an altitude of 85 km and a velocity of 7 km/s during Earth entry. A steady vortex forms in the near wake for these freestream conditions for both chemically reactive and nonreactive air gas models, The size (axial length) of the vortex for the reactive air calculations is 25% larger than that of the nonreactive air calculations. The forebody surface quantities are less sensitive to the chemistry than the base surface quantities. The presence of the afterbody has no effect on the forebody flow structure or the surface quantities. The comparisons of DSMC and Navier-Stokes calculations show good agreement for the wake structure and the forebody surface quantities. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. N CAROLINA STATE UNIV,DEPT MECH & AEROSP ENGN,RALEIGH,NC 27695. RP DOGRA, VK (reprint author), VIGYAN INC,HAMPTON,VA 23666, USA. NR 21 TC 13 Z9 13 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 1995 VL 33 IS 3 BP 463 EP 469 DI 10.2514/3.12426 PG 7 WC Engineering, Aerospace SC Engineering GA QQ967 UT WOS:A1995QQ96700010 ER PT J AU REZAEEPAZHAND, J SIMITSES, GJ STARNES, JH AF REZAEEPAZHAND, J SIMITSES, GJ STARNES, JH TI DESIGN OF SCALED DOWN MODELS FOR STABILITY OF LAMINATED PLATES SO AIAA JOURNAL LA English DT Article AB This study investigates problems associated with design of scaled down models. Similitude theory is employed to develop the necessary similarity conditions. Sealing laws provide the relationship between a full-scale structure and its scale models and fan be used to extrapolate the experimental data of a small, inexpensive, and easily tested model into design information for the large prototype. Both complete and partial similarity are discussed. Particular emphasis is placed on the cases of buckling of rectangular symmetric angle-ply laminated plates under uniaxial compressive and shear loads. This analytical study indicates that distorted models with a different number of layers, material properties, and geometries than those of the prototype can predict the behavior of the prototype with good accuracy. C1 NASA,LANGLEY RES CTR,AC STRUCT BRANCH,HAMPTON,VA 23665. RP REZAEEPAZHAND, J (reprint author), UNIV CINCINNATI,DEPT AEROSP ENGN & ENGN MECH,CINCINNATI,OH 45221, USA. OI Rezaeepazhand, Jalil/0000-0003-3653-1623 NR 6 TC 19 Z9 20 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 1995 VL 33 IS 3 BP 515 EP 519 DI 10.2514/3.12475 PG 5 WC Engineering, Aerospace SC Engineering GA QQ967 UT WOS:A1995QQ96700017 ER PT J AU OZCAN, O SIMPSON, RL AF OZCAN, O SIMPSON, RL TI WAKES OF 3 AXISYMMETRICAL BODIES AT ZERO ANGLE-OF-ATTACK - COMMENT SO AIAA JOURNAL LA English DT Letter C1 NASA,AMES RES CTR,MODELING & EXPTL VALIDAT BRANCH,MOFFETT FIELD,CA 94035. VIRGINIA POLYTECH INST & STATE UNIV,DEPT AEROSP & OCEAN ENGN,BLACKSBURG,VA 24060. RP OZCAN, O (reprint author), ISTANBUL TECH UNIV,FAC AERONAUT & ASTRONAUT,ISTANBUL 80626,TURKEY. NR 11 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0001-1452 J9 AIAA J JI AIAA J. PD MAR PY 1995 VL 33 IS 3 BP 569 EP 570 DI 10.2514/3.12410 PG 2 WC Engineering, Aerospace SC Engineering GA QQ967 UT WOS:A1995QQ96700030 ER PT J AU WADA, F SAGAWA, S MIKI, K NAGAYA, K NAKAMITSU, S SHIRAKI, K GREENLEAF, JE AF WADA, F SAGAWA, S MIKI, K NAGAYA, K NAKAMITSU, S SHIRAKI, K GREENLEAF, JE TI MECHANISM OF THIRST ATTENUATION DURING HEAD-OUT WATER IMMERSION IN MEN SO AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY LA English DT Article DE PLASMA VOLUME; PLASMA OSMOLALITY; PLASMA ARGININE VASOPRESSIN; PLASMA RENIN ACTIVITY; PLASMA ATRIAL NATRIURETIC PEPTIDE ID PLASMA VASOPRESSIN; DRINKING; VOLUME; HUMANS; DEHYDRATION; FLUID; SUPPRESSION; IMPEDANCE; PEPTIDE; STRESS AB The purpose was to determine whether extracellular volume or osmolality was the major contributing factor for reduction of thirst in air and head-out water immersion in hypohydrated subjects. Eight males (19-25 yr) were subjected to thermoneutral immersion and thermoneutral air under two hydration conditions without further drinking: euhydration in water (Eu-H2O) and euhydration in air, and hypohydration in water (Hypo-H2O) and hypohydration in air (3.7% wt loss after exercise in heat). The increased thirst sensation with Hypo-H2O decreased (P < 0.05) within 10 min of immersion and continued thereafter. Mean plasma osmolality (288 +/- 1 mosmol/kgH(2)O) and sodium (140 +/- 1 meq/l) remained elevated, and plasma volume increased by 4.2 +/- 1.0% (P < 0.05) throughout Hypo-H2O. A sustained increase (P < 0.05) in stroke volume accompanied the prompt and sustained decrease in plasma renin activity and sustained increase (P < 0.05) in plasma atrial natriuretic peptide during Eu-H2O and Hypo-H2O. Plasma vasopressin decreased from 5.3 +/- 0.7 to 2.9 +/- 0.5 pg/ml (P < 0.05) during Hypo-H2O but was unchanged in Eu-H2O. These findings suggest a sustained stimulation of the atrial baroreceptors and reduction of a dipsogenic stimulus without major alterations of extracellular osmolality in Hypo-H2O. Thus it appears that vascular volume-induced stimuli of cardiopulmonary baroreceptors play a more important role than extracellular osmolality in reducing thirst sensations during immersion in hypohydrated subjects. C1 UNIV OCCUPAT & ENVIRONM HLTH, SCH MED, DEPT PHYSIOL, YAHATANISHI KU, KITAKYUSHU, FUKUOKA 807, JAPAN. NASA, AMES RES CTR, DIV LIFE SCI, HUMAN ENVIRONM PHYSIOL LAB, MOFFETT FIELD, CA 94035 USA. NR 33 TC 21 Z9 21 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 0363-6119 J9 AM J PHYSIOL-REG I JI Am. J. Physiol.-Regulat. Integr. Compar. Physiol. PD MAR PY 1995 VL 268 IS 3 BP R583 EP R589 PG 7 WC Physiology SC Physiology GA QL386 UT WOS:A1995QL38600002 PM 7900899 ER PT J AU DELCOURT, DC MARTIN, RF SAUVAUD, JA MOORE, TE AF DELCOURT, DC MARTIN, RF SAUVAUD, JA MOORE, TE TI CENTRIFUGAL TRAPPING IN THE MAGNETOTAIL SO ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES LA English DT Article ID ACCELERATION; DYNAMICS AB Particles leaving the neutral sheet in the distant magnetotail at times display adiabatic trajectory sequences characterized by an inflection toward the equator and subsequent mirroring in its vicinity. We demonstrate that this low-latitude mirroring results primarily from a centrifugal deceleration due to the fast direction-changing E x B drift. This effect which we refer to as ''centrifugal trapping'' appears both in guiding centre and full particle treatments. It thus does not directly relate to nonadiabatic motion. However, pitch angle scattering due to nonadiabatic neutral sheet interaction does play a role in reducing the parallel speed of the particles. We show that centrifugal trapping is an important mechanism for the confinement of the slowest (typically below the equatorial E x B drift speed) plasma sheet populations to the midplane vicinity. C1 CNRS,CESR,TOULOUSE,FRANCE. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUNTSVILLE,AL 35812. RP DELCOURT, DC (reprint author), CNRS,CETP,ST MAUR FOSSES,FRANCE. RI Moore, Thomas/D-4675-2012 OI Moore, Thomas/0000-0002-3150-1137 NR 11 TC 4 Z9 4 U1 0 U2 1 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0992-7689 J9 ANN GEOPHYS JI Ann. Geophys.-Atmos. Hydrospheres Space Sci. PD MAR PY 1995 VL 13 IS 3 BP 242 EP 246 DI 10.1007/s00585-995-0242-5 PG 5 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA QP656 UT WOS:A1995QP65600003 ER PT J AU OMIDVAR, K PESNELL, WD AF OMIDVAR, K PESNELL, WD TI HIGH-SPEED CORRECTION FACTOR TO THE O+-O RESONANCE CHARGE-EXCHANGE COLLISION FREQUENCY SO ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES LA English DT Article AB The high-speed correction factor to the O+-O collision frequency, resulting from drift velocities between ions and neutrals, is calculated by solving the integral expression in this factor both numerically and analytically. Although the analytic solution is valid for either small or large drift velocities between ions and neutrals, for temperatures of interest and allo drift velocities considered, agreement is found between analytic and detailed numerical integration results within less than 1% error. Let T-r designate the average of the ion and neutral temperatures in K, and u = upsilon(d)/alpha, where upsilon(d), is the relative drift velocity in cm s(-1), and alpha = 4.56 x 10(3) root T-r cm s(-1) is the thermal velocity of the O+-O system. Then, as u ranges from 0 to 2, the correction factor multiplying the collision frequency increases monotonically from 1 to about 1.5. An interesting result emerging from this calculation is that the correction factor for temperatures of aeronomical interest is to a good approximation independent of the temperature, depending only on the scaled velocity u. C1 APPL RES CORP,LANDOVER,MD 20785. RP OMIDVAR, K (reprint author), NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,GREENBELT,MD 20771, USA. RI Pesnell, William/D-1062-2012 OI Pesnell, William/0000-0002-8306-2500 NR 8 TC 1 Z9 1 U1 0 U2 0 PU SPRINGER VERLAG PI NEW YORK PA 175 FIFTH AVE, NEW YORK, NY 10010 SN 0992-7689 J9 ANN GEOPHYS JI Ann. Geophys.-Atmos. Hydrospheres Space Sci. PD MAR PY 1995 VL 13 IS 3 BP 253 EP 255 DI 10.1007/s005850050160 PG 3 WC Astronomy & Astrophysics; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Astronomy & Astrophysics; Geology; Meteorology & Atmospheric Sciences GA QP656 UT WOS:A1995QP65600005 ER PT J AU EVANS, BR MARGALIT, R WOODWARD, J AF EVANS, BR MARGALIT, R WOODWARD, J TI ENHANCED HYDROLYSIS OF SOLUBLE CELLULOSIC SUBSTRATES BY A METALLOCELLULASE WITH VERATRYL ALCOHOL-OXIDASE ACTIVITY SO APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY LA English DT Article; Proceedings Paper CT 16th Symposium on Biotechnology for Fuels and Chemicals CY MAY 09-13, 1994 CL GATLINBURG, TN SP US DOE, BIOFUELS SYST DIV, ADV IND CONCEPTS DIV, OAK RIDGE NATL LAB, NATL RENEWABLE ENERGY LAB, IDAHO NATL ENG LAB, AMOCO CORP, ARCHER DANIELS MIDLAND CO, BIO TECH RESOURCES L P, DORR OLIVER INC, ENZYME BIO SYST LTD, GENENCOR INT, GIST BROCADES, GOLDEN TECHNOL CO LNC, GRAIN PROC CORP, MARTIN MARIETTA ENERGY SYST INC, MICHIGAN BIOTECHNOL INST, NEW ENERGY CO INDIANA L P, PROC SYST INC, RAPHAEL KATZEN ASSOC INT INC, ROQUETTE AMER INC, SOLVAY ENZYMES INC, A E STALEY, WEYERHAEUSER, AMER CHEM SOC, DIV BIOCHEM TECHNOL DE CELLULASE; METALLOCELLULASE; CELLOBIOHYDROLASE II; TRICHODERMA REESEI; RUTHENIUM; MODIFICATION ID TRICHODERMA-REESEI; CELLOBIOHYDROLASE-II; FUNGAL CELLULASES; ENZYMES AB A cellulase enzyme fraction was separated from Trichoderma reesei Pulpzyme HA(TM), and its characteristics suggested that it was mainly composed of cellobiohydrolase II (CBH II). The covalent attachment of pentaammineruthenium(III) to this enzyme resulted in threefold and fourfold enhancements of its hydrolytic activity on carboxymethyl cellulose (CMC) and barley beta-glucan, respectively, as well as endowing it with veratryl alcohol-oxidase activity. Enhancement of hydrolysis was not affected by addition of tartrate or hydrogen peroxide to the reaction mixture. Both native and pentaammineruthenium-modified enzymes had negligible activity on cellobiose and p-nitrophenyl beta-cellobioside (PNPC). C1 OAK RIDGE NATL LAB, DIV CHEM TECHNOL, OAK RIDGE, TN 37831 USA. JET PROPULS LAB, PASADENA, CA USA. NR 19 TC 4 Z9 4 U1 0 U2 0 PU HUMANA PRESS INC PI TOTOWA PA 999 RIVERVIEW DRIVE SUITE 208, TOTOWA, NJ 07512 USA SN 0273-2289 J9 APPL BIOCHEM BIOTECH JI Appl. Biochem. Biotechnol. PD SPR PY 1995 VL 51-2 BP 225 EP 239 DI 10.1007/BF02933426 PG 15 WC Biochemistry & Molecular Biology; Biotechnology & Applied Microbiology SC Biochemistry & Molecular Biology; Biotechnology & Applied Microbiology GA QW150 UT WOS:A1995QW15000022 ER PT J AU JAMESON, L AF JAMESON, L TI ON THE SPLINE-BASED WAVELET DIFFERENTIATION MATRIX SO APPLIED NUMERICAL MATHEMATICS LA English DT Article DE WAVELET APPROXIMATION; DIFFERENTIATION MATRIX; SUPERCONVERGENCE; COMPACT FINITE DIFFERENCE SCHEMES AB The differentiation matrix for a spline-based wavelet basis without decomposition at multiple scales is constructed. It is shown that regardless of the properties that one imposes on a spline basis, the differentiation matrix is always the one encountered when the basis is simply the B-spline basis. The order of accuracy of this differentiation matrix is shown to display superconvergence. Furthermore, it is shown that spline-based bases generate a class of compact finite difference schemes. With this knowledge boundary conditions of the proper order of accuracy can be imposed. RP JAMESON, L (reprint author), NASA,LANGLEY RES CTR,INST COMP APPLICAT SCI & ENGN,HAMPTON,VA 23681, USA. NR 16 TC 11 Z9 11 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 1995 VL 17 IS 1 BP 33 EP 45 DI 10.1016/0168-9274(95)00005-F PG 13 WC Mathematics, Applied SC Mathematics GA QY327 UT WOS:A1995QY32700003 ER PT J AU PEPPER, SV AF PEPPER, SV TI CHARACTERIZATION AND APPLICATION OF A GRAZING ANGLE OBJECTIVE FOR QUANTITATIVE INFRARED REFLECTION MICROSPECTROSCOPY SO APPLIED SPECTROSCOPY LA English DT Article DE INFRARED; MICROSPECTROSCOPY; THIN FILMS ID IR AB A grazing angle objective on an infrared microspectrometer is studied for quantitative spectroscopy by considering the angular dependence of the incident intensity within the objective's angular aperture. The assumption that there is no angular dependence is tested by comparing the experimental reflectance of Si and KBr surfaces with the reflectance calculated by integrating the Fresnel reflection coefficient over the angular aperture under this assumption. Good agreement was found, indicating that the specular reflectance of surfaces can straightforwardly be quantitatively integrated over the angular aperture without considering nonuniform incident intensity. This quantitative approach is applied to the thickness determination of dipcoated Krytox on gold. The infrared optical constants of both materials are known, allowing the integration to be carried out. The thickness obtained is in fair agreement with the value determined by ellipsometry in the visible. Therefore, this paper illustrates a method for more quantitative use of a grazing angle objective for infrared reflectance microspectroscopy. RP PEPPER, SV (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 15 TC 8 Z9 8 U1 2 U2 2 PU SOC APPLIED SPECTROSCOPY PI FREDERICK PA PO BOX 1438, FREDERICK, MD 21701 SN 0003-7028 J9 APPL SPECTROSC JI Appl. Spectrosc. PD MAR PY 1995 VL 49 IS 3 BP 354 EP 360 DI 10.1366/0003702953963445 PG 7 WC Instruments & Instrumentation; Spectroscopy SC Instruments & Instrumentation; Spectroscopy GA QM508 UT WOS:A1995QM50800014 ER PT J AU WEISTROP, D HINTZEN, P LIU, C LOWENTHAL, J CHENG, KP OLIVERSEN, R BROWN, L WOODGATE, B AF WEISTROP, D HINTZEN, P LIU, C LOWENTHAL, J CHENG, KP OLIVERSEN, R BROWN, L WOODGATE, B TI H-ALPHA IMAGING OF GALAXIES IN THE BOOTES VOID SO ASTRONOMICAL JOURNAL LA English DT Article ID EMISSION-LINE GALAXIES; NORTHERN SKY SURVEY; IRAS GALAXIES; GALACTIC NUCLEI; STAR FORMATION; REGION; SAMPLE; UNIVERSE; SEYFERT; GAS C1 UNIV ARIZONA,STEWARD OBSERV,TUCSON,AZ 85721. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP WEISTROP, D (reprint author), UNIV NEVADA,DEPT PHYS,LAS VEGAS,NV 89154, USA. OI Weistrop, Donna/0000-0001-8935-0792 NR 40 TC 22 Z9 22 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 1995 VL 109 IS 3 BP 981 EP 989 DI 10.1086/117335 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QK478 UT WOS:A1995QK47800008 ER PT J AU MIKOLAJEWSKA, J KENYON, SJ MIKOLAJEWSKI, M GARCIA, MR POLIDAN, RS AF MIKOLAJEWSKA, J KENYON, SJ MIKOLAJEWSKI, M GARCIA, MR POLIDAN, RS TI EVOLUTION OF THE SYMBIOTIC BINARY-SYSTEM AG DRACONIS SO ASTRONOMICAL JOURNAL LA English DT Review ID ACCRETION DISK MODELS; MASS WHITE-DWARFS; X-RAY; IUE OBSERVATIONS; SPECTROSCOPIC ORBITS; INHOMOGENEOUS-MEDIUM; INFRARED PHOTOMETRY; SPECTRAL VARIATIONS; PLANETARY-NEBULAE; BOUNDARY-LAYERS C1 CNRS,INST ASTROPHYS,F-75014 PARIS,FRANCE. HARVARD SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138. NICHOLAS COPERNICUS UNIV,INST ASTRON,PL-87100 TORUN,POLAND. NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. RP MIKOLAJEWSKA, J (reprint author), NICOLAS COPERNICUS ASTRON CTR,BARTYCKA 18,PL-00716 WARSAW,POLAND. NR 124 TC 72 Z9 72 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 1995 VL 109 IS 3 BP 1289 EP 1307 DI 10.1086/117361 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QK478 UT WOS:A1995QK47800034 ER PT J AU JENNISKENS, P AF JENNISKENS, P TI METEOR STREAM ACTIVITY .2. METEOR OUTBURSTS SO ASTRONOMY & ASTROPHYSICS LA English DT Review DE METEORS, METEOROIDS ID COMETARY DUST TRAILS; EVOLUTION; SHOWER; SKJELLERUP; ORBITS; TUTTLE; JAPAN AB In the past two centuries, alert amateur and professional meteor astronomers have documented 35 outbursts of 17 individual meteor streams well enough to allow the construction of a homogeneous set of activity curves. These curves add to similar profiles of the annual streams in a previous paper (Paper I). This paper attempts to define the type and range of phenomena that classify as meteor outbursts from which the following is concluded: Outbursts are associated with the return of the comet to perihelion (near-comet type outburst), but occur also when the parent comet is far from perihelion and far from the Earth (far-comet type). All outbursts of a given stream are of one type only, depending on encounter geometry. The activity curves, expressed in terms of Zenith Hourly Rates (ZHR), have a shape that is usually well described by: ZHR = ZHR(max)10(-B\lambda.-lambda.max\). The steepness of the slopes varies from an exponent of B = 7 to B = 220 per degree of solar longitude, with a typical value of B = 30. In addition, most near-comet type outbursts have a broader component underlying the main peak with B similar to 1-7. The duration (Delta t similar to 1/B) of the main peak is almost independent of location near the comet, while the background component varies considerably in duration and relative intensity from one return to another. The two components in the activity curve are due to two distinct structures in the dust distribution near the parent comet, where the main component can be due to a sheet of dust that emanates from the IRAS dust trail. This brings the total number of distinct structures in meteor streams to four, including the two structures found from the annual stream activity curves in Paper I. C1 DUTCH METEOR SOC, 2318 NB LEIDEN, NETHERLANDS. RP NASA, AMES RES CTR, MAIL STOP 239-4, MOFFETT FIELD, CA 94035 USA. NR 222 TC 93 Z9 93 U1 0 U2 0 PU EDP SCIENCES S A PI LES ULIS CEDEX A PA 17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE SN 1432-0746 J9 ASTRON ASTROPHYS JI Astron. Astrophys. PD MAR PY 1995 VL 295 IS 1 BP 206 EP 235 PG 30 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL104 UT WOS:A1995QL10400026 ER PT J AU BLOM, J BLOEMEN, H BENNETT, K COLLMAR, W HERMSEN, W MCCONNELL, M SCHONFELDER, V STACY, JG STEINLE, H STRONG, A WINKLER, C AF BLOM, J BLOEMEN, H BENNETT, K COLLMAR, W HERMSEN, W MCCONNELL, M SCHONFELDER, V STACY, JG STEINLE, H STRONG, A WINKLER, C TI COMPTEL GAMMA-RAY OBSERVATIONS OF THE QUASARS CTA-102 AND 3C-454.3 SO ASTRONOMY & ASTROPHYSICS LA English DT Article DE GAMMA RAYS, OBSERVATIONS; GALAXIES, BL LACERTAE, INDIVIDUAL, CTA 102, 3C 454.3; GALAXIES, GENERAL ID EXTRAGALACTIC RADIO-SOURCES; EGRET; EMISSION; 3C-279; RADIATION; TELESCOPE; VLBI AB The blazar-type active galactic nuclei CTA 102 (QSO 2230+114) and 3C 454.3 (QSO 2251+158), located about 7 degrees apart, were observed by the Compton Gamma Ray Observatory at four epochs in 1992. Both were detected by EGRET. The combined COMPTEL observations in the 10-30 MeV energy range clearly indicate a source of MeV emission, which is likely due to a contribution from both quasars. These observations strongly suggest that the power-law spectra measured by EGRET above similar to 50 MeV flatten at lower MeV energies. A comparison with observations at other wavelengths shows that the power spectra of CTA 102 and 3C 454.3 peak at MeV energies. This behaviour appears to be a common feature of gamma-ray AGNs. C1 MAX PLANCK INST EXTRATERR PHYS, D-85740 GARCHING, GERMANY. UNIV NEW HAMPSHIRE, CTR SPACE SCI, DURHAM, NH 03824 USA. ESTEC, DIV ASTROPHYS, 2200 AG NOORDWIJK, NETHERLANDS. NASA, GODDARD SPACE FLIGHT CTR, COMPTON OBSERV, CTR SCI SUPPORT, GREENBELT, MD 20771 USA. RP BLOM, J (reprint author), SRON, SORBONNE LAAN 2, 3584 CA UTRECHT, NETHERLANDS. OI Blom, Jan/0000-0003-3408-3409 NR 34 TC 31 Z9 33 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 1995 VL 295 IS 2 BP 330 EP 334 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QM277 UT WOS:A1995QM27700012 ER PT J AU DAHLEM, M KREYSING, HC WHITE, SM ENGELS, D CONDON, JJ HARMON, BA ZHANG, SN KOUVELIOTOU, C PACIESAS, WS VOGES, W AF DAHLEM, M KREYSING, HC WHITE, SM ENGELS, D CONDON, JJ HARMON, BA ZHANG, SN KOUVELIOTOU, C PACIESAS, WS VOGES, W TI RE J1255+266 - DETECTION OF AN EXTREMELY BRIGHT EUV TRANSIENT SO ASTRONOMY & ASTROPHYSICS LA English DT Letter DE STARS, FLARE; STARS, VARIABLES; GAMMA RAYS, OBSERVATIONS; ULTRAVIOLET, GENERAL; X-RAYS, BURSTS ID CATALOG AB During a pointed ROSAT observation in the direction of the Coma cluster of galaxies an exceptionally bright EUV source, RE J1255+266, was detected serendipitously. The source is located close to the Galactic North pole, at b(II) similar or equal to 89 degrees. Its observed EUV flux (62-110 eV) at the time of the detection was of order 710(-9) ergs s(-1) cm(-2), making RE J1255+266 temporarily one of the brightest EUV sources on the sky. The EUV flare of RE J1255+266 has a light curve with a decay time of about 0.86 days. With respect to earlier nondetections, the source brightened by a factor of similar to 7000. Such a behaviour has not been observed before. Thus, it is unclear what type of source RE J1255+266 might be. Up to now no positive identification with any known source could be obtained. Emission at the position of the source was previously only detected in the 1987 Green Bank radio continuum survey. Simultaneous observations with CGRO/BATSE resulted in non-detections of the source in the 8-50 keV energy range. C1 UNIV TUBINGEN, INST ASTRON, D-72076 TUBINGEN, GERMANY. UNIV MARYLAND, DEPT ASTRON, COLLEGE PK, MD 20742 USA. HAMBURGER STERNWARTE, D-21029 HAMBURG, GERMANY. NATL RADIO ASTRON OBSERV, CHARLOTTESVILLE, VA 22903 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, UNIV SPACE RES ASSOC, HUNTSVILLE, AL 35812 USA. UNIV ALABAMA, NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, HUNTSVILLE, AL 35812 USA. MAX PLANCK INST EXTRATERR PHYS, D-85740 GARCHING, GERMANY. RP DAHLEM, M (reprint author), SPACE TELESCOPE SCI INST, 3700 SAN MARTIN DR, BALTIMORE, MD 21218 USA. NR 24 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 MAR PY 1995 VL 295 IS 1 BP L13 EP L16 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL104 UT WOS:A1995QL10400004 ER PT J AU SMITH, EP ODEA, CP BAUM, SA AF SMITH, EP ODEA, CP BAUM, SA TI THE MEGAPARSEC-SCALE ENVIRONMENTS OF BL-LACERTAE OBJECTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE BL LACERTAE OBJECTS, GENERAL; GALAXIES, CLUSTERS, GENERAL ID POWERFUL RADIO GALAXIES; RILEY-I GALAXIES; LAC OBJECTS; CLUSTER ENVIRONMENTS; PARENT POPULATION; COMPLETE SAMPLE; NUMBER COUNTS; CONSTRAINTS; BLAZARS; QUASARS AB We compare observations of BL Lac megaparsec-scale clustering environments with those for F-R I radio galaxies. V and R image data are used to show that the strengths of the clustering measured via spatial cross-correlation amplitude are similar for the two types of galaxies and are consistent with Abel richness class 0. We discuss the implications this has for the origin of the BL Lac phenomena. We also examine the evolution of clustering environments of F-R I radio galaxies and BL Lac objects with redshift. C1 NASA,GODDARD SPACE FLIGHT CTR,ASTRON & SOLAR PHYS LAB,GREENBELT,MD 20771. SPACE TELESCOPE SCI INST,BALTIMORE,MD 21218. NR 49 TC 31 Z9 31 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 1995 VL 441 IS 1 BP 113 EP 119 DI 10.1086/175340 PN 1 PG 7 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QJ099 UT WOS:A1995QJ09900011 ER PT J AU BERGIN, EA LANGER, WD GOLDSMITH, PF AF BERGIN, EA LANGER, WD GOLDSMITH, PF TI GAS-PHASE CHEMISTRY IN DENSE INTERSTELLAR CLOUDS INCLUDING GRAIN SURFACE MOLECULAR DEPLETION AND DESORPTION SO ASTROPHYSICAL JOURNAL LA English DT Article DE DUST, EXTINCTION; ISM, MOLECULES; MOLECULAR PROCESSES ID INTER-STELLAR CLOUDS; TAURUS DARK CLOUDS; INFRARED-SPECTROSCOPY; CARBON-MONOXIDE; CHEMICAL-MODELS; DIFFUSE CLOUDS; SOLID CO; DUST; ABUNDANCES; COMPLEX AB We present time-dependent models of the chemical evolution of molecular clouds which include depletion of atoms and molecules onto grain surfaces and desorption, as well as gas-phase interactions. We have included three mechanisms to remove species from the grain mantles: thermal evaporation, cosmic-ray-induced heating, and photodesorption. A wide range of parameter space has been explored to examine the abundance of species present both on the grain mantles and in the gas phase as a function of both position in the cloud (visual extinction) and of evolutionary state (time). The dominant mechanism that removes molecules from the grain mantles is cosmic-ray desorption. At times greater than the depletion timescale, the abundances of some simple species agree with abundances observed in the cold dark cloud TMC-1. Even though cosmic-ray desorption preserves the gas-phase chemistry at late times, molecules do show significant depletions from the gas phase. Examination of the dependence of depletion as a function of density shows that when the density increases from 10(3) cm-3 to 10(5) cm-3 several species including HCO+, HCN, and CN show gas-phase abundance reductions of over an order of magnitude. The CO:H2O ratio in the grain mantles for our standard model is on the order of 10:1, in reasonable agreement with observations of nonpolar CO ice features in rho Ophiuchus and Serpens. We have also examined the interdependence of CO depletion with the space density of molecular hydrogen and binding energy to the grain surface. We find that the observed depletion of CO in Taurus is inconsistent with CO bonding in an H2O rich mantle, in agreement with observations. We suggest that if interstellar grains consist of an outer layer of CO ice, then the binding energies for many species to the grain mantle may be lower than commonly used, and a significant portion of molecular material may be maintained in the gas phase. C1 JET PROP LAB,PASADENA,CA 91109. CORNELL UNIV,DEPT ASTRON,NATL ASTRON & IONOSPHERE CTR,ITHACA,NY 14853. RP BERGIN, EA (reprint author), UNIV MASSACHUSETTS,FIVE COLL RADIO ASTRON OBSERV,DEPT PHYS & ASTRON,AMHERST,MA 01003, USA. RI Goldsmith, Paul/H-3159-2016 NR 79 TC 169 Z9 169 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 1 PY 1995 VL 441 IS 1 BP 222 EP 243 DI 10.1086/175351 PN 1 PG 22 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QJ099 UT WOS:A1995QJ09900021 ER PT J AU REACH, WT POUND, MW WILNER, DJ LEE, YG AF REACH, WT POUND, MW WILNER, DJ LEE, YG TI DENSE GAS IN HIGH-LATITUDE MOLECULAR CLOUDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ISM, CLOUDS; ISM, MOLECULES; STARS, FORMATION ID HIGH GALACTIC LATITUDES; SPECTROSCOPIC ANALYSIS; STAR FORMATION; CIRRUS CLOUDS; IRAS SOURCES; CHEMISTRY; DISTANCES; CORES; CO; EXTINCTIONS AB The nearby molecular clouds MBM 7, 12, 30, 32, 40, 41, and 55 were surveyed for tracers of dense gas, including the (1-0), (2-1), and (3-2) rotational lines of CS and the (1-0) lines of HCO+ and HCN. MBM 7 and MBM 12 contain dense cores, while the other clouds contain little or no traces of dense gas. Comparison of the emission from dense gas tracers to that of CO-13 reveals that the former are more compact in angular size as well as line width. An extensive CS(2-1) survey of part of MBM 12 reveals that the emission is characterized by clumps on approximately 3' scales as well as extended emission. Observations of the CS(1-0) and (3-2) lines using telescopes with matched beam sizes reveal that the volume density must be at least approximately 10(4.5) cm-3 within the (3-2) emitting regions, which are approximately 0.03 pc in radius. Electron excitation of the CS rotational levels is ruled out (in the cores) by comparing the (3-2)/(1-0) line ratios with models including H2 and electron collisions. The volume density in the cores is substantially larger than in the portions of the cloud traced by CO emission. The density increases into the cores as r-2, suggesting dynamical collapse. The masses of the cores are close to the virial mass, suggesting they are dynamically bound. The cores in MBM 7 and MBM 12 are thus likely to form stars; they are the nearest sites of star formation. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. RP REACH, WT (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,CODE 685,GREENBELT,MD 20771, USA. RI Reach, William/C-4710-2008; Pound, Marc/A-1600-2010; OI Reach, William/0000-0001-8362-4094 NR 48 TC 17 Z9 17 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 1995 VL 441 IS 1 BP 244 EP 260 DI 10.1086/175352 PN 1 PG 17 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QJ099 UT WOS:A1995QJ09900022 ER PT J AU DIGEL, SW HUNTGER, SD MUKHERJEE, R AF DIGEL, SW HUNTGER, SD MUKHERJEE, R TI EGRET OBSERVATIONS OF GAMMA-RAY EMISSION FROM THE INTERSTELLAR GAS IN ORION SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, OBSERVATIONS; ISM, CLOUDS; ISM, MOLECULES; RADIO LINES, ISM ID MOLECULAR CLOUD COMPLEXES; RADIAL-DISTRIBUTION; OUTER GALAXY; COSMIC-RAY; MILKY-WAY; CO SURVEY; CALIBRATION; LUMINOSITY; MONOCEROS AB The high-energy diffuse gamma-ray emission from the interstellar gas in Orion was studied using observations from the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma-Ray Observatory and radio surveys of the H I and CO emission. The good correlation of the gamma-ray emission with the atomic and molecular gas permits determination of the gamma-ray emissivity per nucleon in the interstellar medium and the molecular mass calibrating ration N(H-2)/W(CO) in Orion. The integral gamma-ray emissivity is (1.7 +/- 0.1) x 10(-26) s-1 sr-1 for E > 100 MeV, in good agreement with expectations from studies of the diffuse emission on larger scales. The N(H-2)/W(CO) ratio is (1.06 +/- 0.14) x 10(20) cm-2 (K km s-1)-1, approximately 40% less than the commonly adopted Galactic average. We find no evidence for variations of the cosmic-ray density or N(H-2)/W(CO) ratio in Orion at the sensitivity and resolution of EGRET. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP DIGEL, SW (reprint author), CTR ASTROPHYS,MS72,60 GARDEN ST,CAMBRIDGE,MA 02138, USA. NR 46 TC 61 Z9 61 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 1995 VL 441 IS 1 BP 270 EP 280 DI 10.1086/175354 PN 1 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QJ099 UT WOS:A1995QJ09900024 ER PT J AU BROSIUS, JW ROBINSON, RD MARAN, SP AF BROSIUS, JW ROBINSON, RD MARAN, SP TI HEATING AND IONIZATION OF STELLAR CHROMOSPHERES BY NONTHERMAL PROTON-BEAMS - IMPLICATIONS FOR IMPULSIVE PHASE, REDSHIFTED LYMAN-ALPHA-RADIATION IN STELLAR FLARES SO ASTROPHYSICAL JOURNAL LA English DT Article DE ACCELERATION OF PARTICLES; RADIATION MECHANISMS, NONTHERMAL; STARS, CHROMOSPHERES; STARS, FLARE ID HARD X-RAY; STRUCTURES OBSERVING CAMPAIGN; SOLAR-FLARES; EMISSION; MICROWAVE; ACCELERATION; MODEL; PLAGE; LIMB; VLA AB We investigate the physical basis for the timescale of impulsive-phase, redshifted Lyman-alpha emission in stellar flares on the assumption that it is determined by energy losses in a nonthermal proton beam that is penetrating the chromosphere from above. The temporal evolution of ionization and heating in representative model chromospheres subjected to such beams is calculated. The treatment of ''stopping'' of beam protons takes into account their interactions with (1) electrons bound in neutral hydrogen, (2) nuclei of neutral hydrogen, (3) free electrons, and (4) ambient thermal protons. We find that, for constant incident beam flux, the system attains an equilibrium with the beam energy input to the chromosphere balanced by radiative losses. In equilibrium, the beam penetration depth is constant, and erosion of the chromosphere ceases. If the redshifted, impulsive-phase stellar flare Lyman-alpha emission is produced by downstreaming hydrogen formed through charge exchange between beam protons and ambient hydrogen, then the emission should end when the beam no longer reaches neutral hydrogen. The durations of representative emission events calculated on this assumption range from 0.1 to 14 s. The stronger the beam, the shorter the timescale over which the redshifted Lyman-alpha emission can be observed. C1 NASA, GODDARD SPACE FLIGHT CTR, COMP SCI CORP, GREENBELT, MD 20771 USA. HUGHES STX CORP, LANHAM, MD 20706 USA. RP NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, CODE 682, GREENBELT, MD 20771 USA. NR 42 TC 9 Z9 9 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 1995 VL 441 IS 1 BP 385 EP 399 DI 10.1086/175362 PN 1 PG 15 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QJ099 UT WOS:A1995QJ09900032 ER PT J AU BRAINERD, JJ MEEGAN, CA BRIGGS, MS PENDLETON, GN BROCK, MN AF BRAINERD, JJ MEEGAN, CA BRIGGS, MS PENDLETON, GN BROCK, MN TI TIME-DEPENDENT CLUSTERING ANALYSIS OF THE 2ND BATSE GAMMA-RAY BURST CATALOG SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS AB A time-dependent two-point correlation-function analysis of the BATSE 2B catalog finds no evidence of burst repetition. As part of this analysis, we discuss the effects of sky exposure on the observability of burst repetition and present the equation describing the signature of burst repetition in the data. For a model of all burst repetition from a source occurring in less than five days we derive upper limits on the number of bursts in the catalog from repeaters and model-dependent upper limits on the fraction of burst sources that produce multiple outbursts. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. RP BRAINERD, JJ (reprint author), UNIV ALABAMA,HUNTSVILLE,AL 35899, USA. NR 8 TC 21 Z9 21 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 1995 VL 441 IS 1 BP L39 EP L42 DI 10.1086/187784 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QJ103 UT WOS:A1995QJ10300011 ER PT J AU HINSHAW, G BENNETT, CL KOGUT, A AF HINSHAW, G BENNETT, CL KOGUT, A TI SIMULATED COSMIC MICROWAVE BACKGROUND MAPS AT 0-DEGREES-5 RESOLUTION - BASIC RESULTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; COSMOLOGY, OBSERVATIONS ID RADIATION ANISOTROPY AB We have simulated full-sky maps of the cosmic microwave background (CMB) anisotropy expected from cold dark matter (CDM) models at 0.5-degrees and 1.0-degrees angular resolution. Statistical properties of the maps are presented as a function of sky coverage, angular resolution, and instrument noise, and the implications of these results for observability of the Doppler peak are discussed. The rms fluctuations in a map are not a particularly robust probe of the existence of a Doppler peak; however, a full correlation analysis can provide reasonable sensitivity. We find that sensitivity to the Doppler peak depends primarily on the fraction of sky covered, and only secondarily on the angular resolution and noise level. Color plates of the simulated maps are presented to illustrate the anisotropies. RP HINSHAW, G (reprint author), HUGHES STX CORP, NASA, GSFC, ASTRON & SOLAR PHYS LAB, CODE 685, GREENBELT, MD 20771 USA. RI Kogut, Alan/D-6293-2012 NR 12 TC 17 Z9 17 U1 1 U2 1 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 1995 VL 441 IS 1 BP L1 EP L4 DI 10.1086/187774 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QJ103 UT WOS:A1995QJ10300001 ER PT J AU KOGUT, A HINSHAW, G BENNETT, CL AF KOGUT, A HINSHAW, G BENNETT, CL TI SIMULATED COSMIC MICROWAVE BACKGROUND MAPS AT 0-DEGREES-5 RESOLUTION - UNRESOLVED FEATURES SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND ID RADIATION ANISOTROPY AB High-contrast peaks in the cosmic microwave background (CMB) anisotropy can appear as unresolved sources to observes. We fit simulated CMB maps generated with a cold dark matter model to a set of unresolved features at instrumental resolution 0.5-degrees-1.5-degrees to derive the integral number density per steradian n(>\T\) of features brighter than threshold temperature \T\ and compare the results to recent experiments. A typical medium-scale experiment observing 0.001 sr at 0.5-degrees resolution would expect to observe one feature brighter than 85 muK after convolution with the beam profile, with less than 5% probability to observe a source brighter than 150 muK. Increasing the power-law index of primordial density perturbations n from 1 to 1.5 raises these temperature limits \T\ by a factor of 2. The MSAM features are in agreement with standard cold dark matter models and are not necessarily evidence for processes beyond the standard model. RP KOGUT, A (reprint author), HUGHES STX CORP,NASA,GSFC,ASTRON & SOLAR PHYS LAB,CODE 685,GREENBELT,MD 20771, USA. RI Kogut, Alan/D-6293-2012 NR 16 TC 4 Z9 4 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD MAR 1 PY 1995 VL 441 IS 1 BP L5 EP L7 DI 10.1086/187775 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QJ103 UT WOS:A1995QJ10300002 ER PT J AU HUTCHINSON, KJ WATENPAUGH, DE MURTHY, G CONVERTINO, VA HARGENS, AR AF HUTCHINSON, KJ WATENPAUGH, DE MURTHY, G CONVERTINO, VA HARGENS, AR TI BACK PAIN DURING 6-DEGREES HEAD-DOWN TILT APPROXIMATES THAT DURING ACTUAL MICROGRAVITY SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Article AB Astronauts often experience back pain during spaceflight, Retrospectively, Wing et al, (14) found that during spaceflight, 14 of 19 Shuttle crewmembers experienced back pain, which they described as dull (62%), localized to the lower back (50%), and with an intensity of 2 on a 5-point scale, Further, the spine lengthens 4-7 cm in microgravity. Our objective wets to compare back pain and spinal lengthening (body height increase) during simulated microgravity (6 degrees head-down tilt, HDT) with the same parameters during actual microgravity. Eight male subjects completed ct modified McGill pain questionnaire with intensity graded from zero (no pain) to five (intense and incapacitating pain) each day tit 7:00 pm during 2 d pre-HDT control, 16 d HDT, and 1 d post-HDT recovery periods, Also, the subjects' heights were measured each day while supine (control and recovery) and during HDT, Back pain increased from zero (pre-tilt control period) to 2.3 +/- 0.4 at days 1 to 3 of HBT, and was categorized as dull and/or burning pain in subjects' lower backs, Only 2 subjects reported any pain after day 9 of HDT and during recovery, Heights increased 2.1 +/- 0.5 cm by day 3 of HDT and remained at that level until the end of the HDT period, Although spinal lengthening in space is greater than that during HDT, the HDT model approximates the level, type, distribution, and time course of back pain associated with actual microgravity. In the HDT model, pain subsides in intensity when spinal lengthening stops, Therefore, back pain in actual and simulated microgravity may result from stretching of spinal and/or paraspinal tissues until a new spinal length is reached. C1 NASA,AMES RES CTR,GRAVITAT RES BRANCH 23911,MOFFETT FIELD,CA 94035. AOCIY,AL,DIV CLIN SCI,PHYSIOL RES BRANCH,BROOKS AFB,TX 78235. NR 14 TC 20 Z9 23 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 1995 VL 66 IS 3 BP 256 EP 259 PG 4 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA QK391 UT WOS:A1995QK39100011 PM 7661837 ER PT J AU POWELL, MR NORFLEET, WT KUMAR, KV BUTLER, BD AF POWELL, MR NORFLEET, WT KUMAR, KV BUTLER, BD TI PATENT FORAMEN OVALE AND HYPOBARIC DECOMPRESSION SO AVIATION SPACE AND ENVIRONMENTAL MEDICINE LA English DT Note ID PARADOXICAL AIR-EMBOLISM; GAS-BUBBLES; CIRCULATION; ULTRASOUND; PASSAGE; DIVERS; SHUNTS; PIGS AB Gels microbubbles were detected in the left ventricle of a supine subject being screened for an atrial septal detect as a participant of a hypobaric decompression study, This determination was made using the saline echocontrast procedure, We found provocation by a Valsalva maneuver not to be necessary in this individual for right-to left passage of contrast microbubbles into the left heart and middle cerebral artery, When this same individual underwent hypobaric decompression to a simulated altitude of 21,000 ft, numerous gas microbubbles were detected in the right heart, but no gels bubbles were detected in either the left ventricular outflow tract or in the middle cerebral artery, This observation appears to be a novel finding, not previously reported. C1 KRUG LIFE SCI,HOUSTON,TX. UNIV TEXAS,SCH MED,DEPT ANESTHESIOL,HOUSTON,TX 77030. RP POWELL, MR (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,SPACE BIOMED RES INST,ENVIRONM PHYSIOL LAB,MAIL CODE SD5,HOUSTON,TX 77058, USA. NR 22 TC 8 Z9 9 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 1995 VL 66 IS 3 BP 273 EP 275 PG 3 WC Public, Environmental & Occupational Health; Medicine, General & Internal; Sport Sciences SC Public, Environmental & Occupational Health; General & Internal Medicine; Sport Sciences GA QK391 UT WOS:A1995QK39100015 PM 7661841 ER PT J AU SERGUTINA, AV GERSHTEIN, LM DAMELIO, F DONTON, N KRASNOV, IB AF SERGUTINA, AV GERSHTEIN, LM DAMELIO, F DONTON, N KRASNOV, IB TI SOME CYTOCHEMICAL PECULIARITIES OF THE RAT-BRAIN MOTOR SYSTEM AFTER SPACE-FLIGHT SO BULLETIN OF EXPERIMENTAL BIOLOGY AND MEDICINE LA English DT Article DE SOMATOSENSORY CORTEX; HEAD OF NUCLEUS CAUDATUS; ENZYME ACTIVITY; RATS; SPACEFLIGHT AB The results of cytochemical cytometry of rat brain suggest that a 9-day exposure of rats to microgravitation conditions lowers the activity of monoaminoxidase in the fibrous structures of layer V of the somatosensory cortex and in the head of nucleus caudatus, as well as the activity of acetylcholine esterase in the bodies of neurons forming the head of n. caudatus. C1 RUSSIAN ACAD MED SCI,INST BRAIN,MOSCOW 109801,RUSSIA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. MINIST HLTH,INST BIOMED PROBLEMS,MOSCOW,RUSSIA. NR 8 TC 0 Z9 0 U1 0 U2 0 PU PLENUM PUBL CORP PI NEW YORK PA CONSULTANTS BUREAU 233 SPRING ST, NEW YORK, NY 10013 SN 0007-4888 J9 B EXP BIOL MED+ JI Bull. Exp. Biol. Med. PD MAR PY 1995 VL 119 IS 3 BP 279 EP 281 DI 10.1007/BF02445835 PG 3 WC Medicine, Research & Experimental SC Research & Experimental Medicine GA TB197 UT WOS:A1995TB19700017 ER PT J AU POLOVINA, JJ MOFFITT, RB AF POLOVINA, JJ MOFFITT, RB TI SPATIAL AND TEMPORAL DISTRIBUTION OF THE PHYLLOSOMA OF THE SPINY LOBSTER, PANULIRUS-MARGINATUS, IN THE NORTHWESTERN HAWAIIAN-ISLANDS SO BULLETIN OF MARINE SCIENCE LA English DT Article ID VERTICAL-DISTRIBUTION; PACIFIC; LARVAE AB The distribution of Panulirus marginatus phyllosomes is relatively homogeneous throughout the Northwestern Hawaiian Islands. Specifically, the very low adult lobster abundance at Lisianski Island is likely not due to a lack of late-stage phyllosomes. The pelagic duration of the larvae of P. marginatus is estimated to be 12 months. Satellite-tracked drifter buoys provide evidence that eddies and the Subtropical Counter Current may retain phyllosomes around the Northwestern Hawaiian Islands for their 12-month pelagic period. RP POLOVINA, JJ (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 12 TC 15 Z9 16 U1 0 U2 0 PU ROSENSTIEL SCH MAR ATMOS SCI PI MIAMI PA 4600 RICKENBACKER CAUSEWAY, MIAMI, FL 33149 SN 0007-4977 J9 B MAR SCI JI Bull. Mar. Sci. PD MAR PY 1995 VL 56 IS 2 BP 406 EP 417 PG 12 WC Marine & Freshwater Biology; Oceanography SC Marine & Freshwater Biology; Oceanography GA QK207 UT WOS:A1995QK20700002 ER PT J AU WALKER, GK SUD, YC ATLAS, R AF WALKER, GK SUD, YC ATLAS, R TI IMPACT OF THE ONGOING AMAZONIAN DEFORESTATION ON LOCAL PRECIPITATION - A GCM SIMULATION STUDY SO BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY LA English DT Article ID GENERAL-CIRCULATION MODELS; TROPICAL DEFORESTATION; BIOSPHERE MODEL; CLIMATE CHANGE; LAND-SURFACE; SCALE; PARAMETERIZATION; TURBULENCE; SIB AB Numerical simulation experiments were conducted to delineate the influence of in situ deforestation data on episodic rainfall by comparing two ensembles of five 5-day integrations performed with a recent version of the Goddard Laboratory for Atmospheres GCM that has a simple biosphere model (SiB). The first set, called control cases, used the standard SiB vegetation cover (comprising 12 biomes) and assumed a fully forested Amazonia, while the second set, called deforestation cases, distinguished the partially deforested regions of Amazonia as savanna. Except for this difference, all other initial and prescribed boundary conditions were kept identical in both sets of integrations. The differential analyses of these five cases show the following local effects of deforestation. 1) A discernible decrease in evapotranspiration of about 0.80 mm d(-1) (roughly 18%) that is quite robust in the averages for 1-, 2-, and 5-day forecasts. 2) A decrease in precipitation of about 1.18 mm d(-1) (roughly 8%) that begins to emerge even in 1-2-day averages and exhibits complex evolution that extends downstream with the winds. A larger decrease in precipitation as compared to evapotranspiration produces some drying and warming. The precipitation differences are consistent with the decrease in atmospheric moisture flux convergence and are consistent with earlier simulation studies of local climate change due to large-scale deforestation. 3) A significant decrease in the surface drag force (as a consequence of reduced surface roughness of deforested regions) that, in turn, affects the dynamical structure of moisture convergence and circulation. The surface winds increase significantly during the first day, and thereafter the increase is well maintained even in the 2- and 5-day averages. C1 NASA,GODDARD SPACE FLIGHT CTR,ATMOSPHERES LAB,CLIMATE & RADIAT BRANCH,GREENBELT,MD 20771. RI Atlas, Robert/A-5963-2011 OI Atlas, Robert/0000-0002-0706-3560 NR 34 TC 24 Z9 26 U1 0 U2 4 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0003-0007 J9 B AM METEOROL SOC JI Bull. Amer. Meteorol. Soc. PD MAR PY 1995 VL 76 IS 3 BP 346 EP 361 DI 10.1175/1520-0477(1995)076<0346:IOTOAD>2.0.CO;2 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QQ319 UT WOS:A1995QQ31900004 ER PT J AU CARTER, GA REBBECK, J PERCY, KE AF CARTER, GA REBBECK, J PERCY, KE TI LEAF OPTICAL-PROPERTIES IN LIRIODENDRON-TULIPIFERA AND PINUS-STROBUS AS INFLUENCED BY INCREASED ATMOSPHERIC OZONE AND CARBON-DIOXIDE SO CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE LA English DT Article ID SPECTRAL REFLECTANCE; CHLOROPHYLL CONTENT; ELEVATED CO2; SLASH PINE; RED EDGE; LEAVES; RESPONSES; NITROGEN; INJURY AB Seedlings of Liriodendron tulipifera L. and Pinus strobus L. were grown in open-top chambers in the field to determine leaf optical responses to increased ozone (O-3) or O-3 and carbon dioxide (CO2). In both species, seedlings were exposed to charcoal-filtered air, air with 1.3 times ambient O-3 concentrations (1.3X), or air with 1.3 times ambient O-3 and 700 mu L . L(-1) CO2 (1.3X + CO2). Exposure to 1.3X increased reflectance in the 633-697 nm range in L. tulipifera. Also, 1.3X decreased transmittance within the 400-420 nm range, increased transmittance at 686-691 nm, and decreased absorptance at 655-695 nm. With 700 mu L . L(-1) CO2, O-3 did not affect reflectance in L. tulipifera, but decreased transmittance and increased absorptance within the 400-421 nm range and increased transmittance and decreased absorptance in the 694-697 nm range. Under 1.3X, reflectance in P. strobus was not affected. However, 1.3X + CO2 increased pine reflectance in the 538-647, 650, and 691-716 nm ranges. Transmittances and absorptances were not determined for P. strobus. Reflectance in both species, and transmittance and absorptance in L. tulipifera, were most sensitive to O-3 near 695 nm. Reflectance at 695 nm, but particularly the ratio of reflectance at 695 nm to reflectance at 760 nm, was related closely to ozone-induced decreases in leaf chlorophyll contents, particularly chlorophyll a (r(2) = 0.82). C1 US FOREST SERV,DELAWARE,OH 43015. NAT RESOURCES CANADA,CANADIAN FOREST SERV,MARITIMES REG,FREDERICTON,NB E3B 5P7,CANADA. RP CARTER, GA (reprint author), NASA,BAY ST LOUIS,MS 39529, USA. NR 27 TC 22 Z9 22 U1 0 U2 2 PU NATL RESEARCH COUNCIL CANADA PI OTTAWA PA RESEARCH JOURNALS, MONTREAL RD, OTTAWA ON K1A 0R6, CANADA SN 0045-5067 J9 CAN J FOREST RES JI Can. J. For. Res.-Rev. Can. Rech. For. PD MAR PY 1995 VL 25 IS 3 BP 407 EP 412 DI 10.1139/x95-045 PG 6 WC Forestry SC Forestry GA QY716 UT WOS:A1995QY71600005 ER PT J AU LEVY, Y BULZAN, DL AF LEVY, Y BULZAN, DL TI ON THE OSCILLATION OF COMBUSTION OF A LAMINAR SPRAY SO COMBUSTION AND FLAME LA English DT Article ID DIFFUSION FLAMES; SCHUMANN AB A spray combustor, with flow velocities in the laminar range, exhibits a unique operating mode where large amplitude, self-induced oscillations of the flame shape occur. The phenomenon, not previously encountered, only occurs when fuel is supplied in the form of fine liquid droplets and does not occur when fuel is supplied in gaseous form. Several flow mechanisms are coupled in such a fashion as to trigger and maintain the oscillatory motion of the flame. These mechanisms include heat transfer and evaporation processes, dynamics of two-phase flows, and effects of gravity (buoyancy forces). An interface volume, lying between the fuel nozzle and the flame was found to be the most susceptible to gravity effects, and postulated to be responsible for inducing the oscillatory motion. Heptane fuel was used in the majority of the tests. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP LEVY, Y (reprint author), TECHNION ISRAEL INST TECHNOL,FAC AEROSP ENGN,IL-32000 HAIFA,ISRAEL. NR 18 TC 8 Z9 8 U1 0 U2 1 PU ELSEVIER SCIENCE PUBL CO INC PI NEW YORK PA 655 AVENUE OF THE AMERICAS, NEW YORK, NY 10010 SN 0010-2180 J9 COMBUST FLAME JI Combust. Flame PD MAR PY 1995 VL 100 IS 4 BP 543 EP 549 DI 10.1016/0010-2180(94)00135-F PG 7 WC Thermodynamics; Energy & Fuels; Engineering, Multidisciplinary; Engineering, Chemical; Engineering, Mechanical SC Thermodynamics; Energy & Fuels; Engineering GA QP526 UT WOS:A1995QP52600003 ER PT J AU KINCAID, RK MARTIN, AD HINKLEY, JA AF KINCAID, RK MARTIN, AD HINKLEY, JA TI HEURISTIC-SEARCH FOR THE POLYMER STRAIGHTENING PROBLEM SO COMPUTATIONAL POLYMER SCIENCE LA English DT Article DE OPTIMIZATION; POLYIMIDES; CRYSTALLIZATION; CONFORMATIONAL SEARCH; TABU SEARCH; ROTATIONAL ISOMERIC STATE MODEL ID THERMOPLASTIC POLYIMIDE; CONFORMATIONS AB A simplified rotational isomeric state model of aromatic polymers was explored. ''Straight'' conformations (ones for which the end bonds of a repeat unit align) were identified using a tabu search procedure. The optimization method was tested with three polyimides and shown to be effective in locating the vicinity of the global optimum. C1 COLL WILLIAM & MARY,DEPT MATH,WILLIAMSBURG,VA 23187. NASA,LANGLEY RES CTR,HAMPTON,VA 23665. NR 21 TC 1 Z9 1 U1 0 U2 0 PU PRA PRESS PI CINCINNATI PA POLYMER RES ASSOC INC 9200 MONTGOMERY RD, SUITE 23B, CINCINNATI, OH 45242 SN 1052-0643 J9 COMPUT POLYMER SCI JI Comput. Polym. Sci. PD MAR-JUN PY 1995 VL 5 IS 1-2 BP 1 EP 5 PG 5 WC Polymer Science SC Polymer Science GA RJ988 UT WOS:A1995RJ98800001 ER PT J AU SHIH, TH LIOU, WW SHABBIR, A YANG, ZG ZHU, J AF SHIH, TH LIOU, WW SHABBIR, A YANG, ZG ZHU, J TI A NEW KAPPA-EPSILON EDDY VISCOSITY MODEL FOR HIGH REYNOLDS-NUMBER TURBULENT FLOWS SO COMPUTERS & FLUIDS LA English DT Article ID CHANNEL; LAYER AB A new k-epsilon eddy viscosity model, which consists of a new model dissipation rate equation and a new realizable eddy viscosity formulation, is proposed in this paper. The new model dissipation rate equation is based on the dynamic equation of the mean-square vorticity fluctuation at large turbulent Reynolds number. The new eddy viscosity formulation is based on the realizability constraints; the positivity of normal Reynolds stresses and the Schwarz' inequality for turbulent shear stresses. We find that the present model with a set of unified model coefficients can perform well for a variety of flows. The flows that are examined include: (i) rotating homogeneous shear hows, (ii) boundary-free shear flows including a mixing layer, planar and round jets; (iii) a channel flow, and flat plate boundary layers with and without a pressure gradient; and (iv) backward facing step separated flows. The model predictions are compared with available experimental data. The results from the standard k-epsilon eddy viscosity model are also included for comparison. It is shown that the present model is a significant improvement over the standard k-epsilon eddy viscosity model. RP SHIH, TH (reprint author), NASA,LEWIS RES CTR,CTR MODELING TURBULENCE & TRANSIT,INST COMPUTAT MECH PROPULS,CLEVELAND,OH 44135, USA. NR 28 TC 1662 Z9 1925 U1 11 U2 101 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0045-7930 J9 COMPUT FLUIDS JI Comput. Fluids PD MAR PY 1995 VL 24 IS 3 BP 227 EP 238 DI 10.1016/0045-7930(94)00032-T PG 12 WC Computer Science, Interdisciplinary Applications; Mechanics SC Computer Science; Mechanics GA QM129 UT WOS:A1995QM12900003 ER PT J AU OTA, D LOFTIN, B SAITO, T LEA, R KELLER, J AF OTA, D LOFTIN, B SAITO, T LEA, R KELLER, J TI VIRTUAL-REALITY IN SURGICAL EDUCATION SO COMPUTERS IN BIOLOGY AND MEDICINE LA English DT Article DE VIRTUAL REALITY; LAPAROSCOPIC SURGERY; SURGICAL EDUCATION; FUZZY LOGIC; COMPETENCE ID FUZZY-SETS AB Virtual reality (VR) is an emerging-technology that can teach surgeons new procedures and can determine their level of competence before they operate on patients. Also VR allows the trainee to return to the same procedure or task several times later as a refresher course. Laparoscopic surgery is a new operative technique which requires the surgeon to observe the operation on a video-monitor and requires the acquisition of new skills. VR simulation could duplicate the operative field and thereby enhance training and reduce the need for expensive animal training models. Our preliminary experience has shown that we have the technology to model tissues and laparoscopic instruments and to develop in real time a VR learning environment for surgeons. Another basic need is to measure competence. Surgical training is an apprenticeship requiring close supervision and 5-7 years of training. Technical competence is judged by the mentor and has always been subjective. If VR surgical simulators are to play an important role in the future, quantitative measurement of competence would have to be a part of the system. Because surgical competence is ''vague'' and is characterized by such terms as ''too long, too short'' or ''too close, too far,'' it is possible that the principles of fuzzy logic could be used to measure competence in a VR surgical simulator. Because a surgical procedure consists of a series of tasks and each task is a series of steps, we will plan to create two important tasks in a VR simulator and validate their, use. These tasks consist of laparoscopic knot tying and laparoscopic suturing. Our hypothesis is that VR in combination with fuzzy logic can educate surgeons and determine when they are competent to perform these procedures on patients. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. UNIV HOUSTON,VIRTUAL ENVIRONM TECHNOL LAB,HOUSTON,TX 77058. UNIV HOUSTON,DEPT COMP SCI,HOUSTON,TX 77058. UNIV HOUSTON,DEPT COMP & MATH SCI,HOUSTON,TX 77058. RP OTA, D (reprint author), UNIV MISSOURI,ELLIS FISCHEL CANC CTR,DIV SURG ONCOL,115 BUSINESS LOOP 70 W,COLUMBIA,MO 65203, USA. NR 32 TC 70 Z9 73 U1 4 U2 9 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0010-4825 J9 COMPUT BIOL MED JI Comput. Biol. Med. PD MAR PY 1995 VL 25 IS 2 BP 127 EP 137 DI 10.1016/0010-4825(94)00009-F PG 11 WC Biology; Computer Science, Interdisciplinary Applications; Engineering, Biomedical; Mathematical & Computational Biology SC Life Sciences & Biomedicine - Other Topics; Computer Science; Engineering; Mathematical & Computational Biology GA RF807 UT WOS:A1995RF80700005 PM 7554831 ER PT J AU POLOVINA, JJ HAIGHT, WR MOFFITT, RB PARRISH, FA AF POLOVINA, JJ HAIGHT, WR MOFFITT, RB PARRISH, FA TI THE ROLE OF BENTHIC HABITAT, OCEANOGRAPHY, AND FISHING ON THE POPULATION-DYNAMICS OF THE SPINY LOBSTER, PANULIRUS-MARGINATUS (DECAPODA, PALINURIDAE), IN THE HAWAIIAN ARCHIPELAGO SO CRUSTACEANA LA English DT Article; Proceedings Paper CT 4th International Workshop on Lobster Biology and Management CY JUL 25-31, 1993 CL KITASATO UNIV, SCH FISHERIES SCI, SANRIKU, JAPAN HO KITASATO UNIV, SCH FISHERIES SCI ID RECRUITMENT AB Temporal and spacial variation in relative abundance and production of spiny lobster Panulirus marginatus in the northwestern Hawaiian islands has been documented from commercial catch-and-effort and research trapping data. Data on benthic habitat collected from scuba transects and data on oceanography, and the pelagic distribution of larval lobsters are used to explain adult lobster temporal and spatial variation. We find the amount of 5-30 cm vertical relief and the height of bank summits explain considerable spatial variation in lobster abundance. Considerable interannual variation in lobster production at the northwestern portion of the fishing grounds is explained by the sea level gradient along the archipelago which appears to measure the strength of the Subtropical Counter Current, Evidence of a 50% drop in recruitment to the fishery has been observed since 1989. Recruitment overfishing and a decadal climate event may be responsible for this recruitment decline. RP POLOVINA, JJ (reprint author), NOAA,NATL MARINE FISHERIES SERV,SW FISHERIES SCI CTR,HONOLULU LAB,2570 DOLE ST,HONOLULU,HI 96822, USA. NR 12 TC 23 Z9 24 U1 0 U2 4 PU E J BRILL PI LEIDEN PA PO BOX 9000, 2300 PA LEIDEN, NETHERLANDS SN 0011-216X J9 CRUSTACEANA JI Crustaceana PD MAR PY 1995 VL 68 BP 203 EP 212 DI 10.1163/156854095X00106 PN 2 PG 10 WC Marine & Freshwater Biology SC Marine & Freshwater Biology GA QK868 UT WOS:A1995QK86800010 ER PT J AU RICHARDSON, MD BRIGGS, KB BOWLES, FA TIETJEN, JH AF RICHARDSON, MD BRIGGS, KB BOWLES, FA TIETJEN, JH TI A DEPAUPERATE BENTHIC ASSEMBLAGE FROM THE NUTRIENT-POOR SEDIMENTS OF THE PUERTO-RICO TRENCH SO DEEP-SEA RESEARCH PART I-OCEANOGRAPHIC RESEARCH PAPERS LA English DT Article ID DEEP-SEA; VENEZUELA BASIN; BIOLOGICAL-ACTIVITY; BOTTOM CURRENTS; CARIBBEAN SEA; PACIFIC; COMMUNITIES; MEIOBENTHOS; ABUNDANCE; ATLANTIC AB The Puerto Rico Trench contains a low-density-biomass assemblage of macrofauna and meiofauna. The depauperate character of this assemblage is primarily the result of the low percentage and refractory nature of organic matter in the sediments. Recent turbidite flows may have contributed to the paucity of fauna. Sediments from this portion of the Puerto Rico Trench are the result of pelagic sedimentation interspersed with thin laminae that probably originated as turbidity flows from the northern and eastern, or deep-sea, walls of the trench. These recently deposited pelagic clays are low in available organic matter. Bioturbation and other mechanical and geochemical processes have not compacted these sediments into a stable, habitable substrate. The ''oligotrophic'' assemblages found in the Puerto Rico Trench contrast with ''eutrophic'' hadal assemblages which inhabit coarser-grained, organic-rich sediments. These types of sediments usually originate as turbidity flows from the walls of island-are trenches proximal to shallow-water shelves and provide a substrate of higher shear strength and greater nutritive value. C1 CUNY CITY COLL, DEPT BIOL, NEW YORK, NY 10031 USA. RP USN, RES LAB, STENNIS SPACE CTR, DIV MARINE GEOSCI, BAY ST LOUIS, MS 39529 USA. NR 46 TC 16 Z9 16 U1 3 U2 7 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND SN 0967-0637 EI 1879-0119 J9 DEEP-SEA RES PT I JI Deep-Sea Res. Part I-Oceanogr. Res. Pap. PD MAR PY 1995 VL 42 IS 3 BP 351 EP 364 DI 10.1016/0967-0637(95)00007-S PG 14 WC Oceanography SC Oceanography GA RE720 UT WOS:A1995RE72000004 ER PT J AU LIU, HS AF LIU, HS TI A NEW VIEW ON THE DRIVING MECHANISM OF MILANKOVITCH GLACIATION CYCLES SO EARTH AND PLANETARY SCIENCE LETTERS LA English DT Article ID ICE-SHEET MODEL; PLEISTOCENE; FLUCTUATIONS; VARIABILITY; ORIGIN AB Dynamical instabilities in the glaciation and deglaciation of the ice sheets can be triggered by pulsations of the rate of change of the orbital and rotational parameters. The purpose of this paper is to demonstrate that the Milankovitch glaciation cycles are extremely sensitive to the rate of change of the obliquity frequency. The first of our three contributions is a pedagogic principle of dynamical instability which provides a scientific basis for the driving mechanism of the glaciation cycles. The second contribution is a clarification of the origin and climate significance of the obliquity related 100 kyr cycle in terms of nonlinear coupling between various orbital and rotational parameters. Finally, the fluctuations in the size of the ice sheets are computed using the Weertman-Birchfield-Watts model of ice sheets. It is demonstrated that the growth and decay of the width of the ice sheets are in good agreement with the variations in the continental ice volume as seen in the late Pleistocene deltaO-18 record. RP LIU, HS (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. NR 36 TC 19 Z9 20 U1 3 U2 5 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0012-821X J9 EARTH PLANET SC LETT JI Earth Planet. Sci. Lett. PD MAR PY 1995 VL 131 IS 1-2 BP 17 EP 26 DI 10.1016/0012-821X(95)00008-Z PG 10 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QP499 UT WOS:A1995QP49900002 ER PT J AU NOOR, AK BURTON, WS PETERS, JM AF NOOR, AK BURTON, WS PETERS, JM TI HIERARCHICAL ADAPTIVE MODELING OF STRUCTURAL SANDWICHES AND MULTILAYERED COMPOSITE PANELS SO ENGINEERING FRACTURE MECHANICS LA English DT Article ID SUPERCONVERGENT PATCH RECOVERY; PREDICTOR-CORRECTOR PROCEDURES; TRANSITION FINITE-ELEMENTS; SHEAR CORRECTION FACTORS; S-VERSION; PLATES; SHELLS; STRESS; LOAD AB Some recent advances in hierarchical modeling strategies are reviewed with special emphasis on applications to multilayered composite panels. Discussion focuses on the key elements of hierarchical adaptive modeling, multimodel predictor-corrector modeling procedures, potential for solving large complex problems and the needed development to realize this potential. Numerical studies are presented for free vibrations of thermally-stressed multilayered composite panels and structural sandwiches with composite face sheets, demonstrating the effectiveness of the multimodel predictor-corrector modeling approaches. RP NOOR, AK (reprint author), UNIV VIRGINIA,NASA,LANGLEY RES CTR,CTR COMPUTAT STRUCT TECHNOL,HAMPTON,VA 23681, USA. NR 44 TC 3 Z9 3 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0013-7944 J9 ENG FRACT MECH JI Eng. Fract. Mech. PD MAR-APR PY 1995 VL 50 IS 5-6 BP 801 EP 817 DI 10.1016/0013-7944(94)E0061-K PG 17 WC Mechanics SC Mechanics GA QP911 UT WOS:A1995QP91100015 ER PT J AU CARPENTER, SR CHRISTENSEN, DL COLE, JJ COTTINGHAM, KL HE, X HODGSON, JR KITCHELL, JF KNIGHT, SE PACE, ML POST, DM SCHINDLER, DE VOICHICK, N AF CARPENTER, SR CHRISTENSEN, DL COLE, JJ COTTINGHAM, KL HE, X HODGSON, JR KITCHELL, JF KNIGHT, SE PACE, ML POST, DM SCHINDLER, DE VOICHICK, N TI BIOLOGICAL-CONTROL OF EUTROPHICATION IN LAKES SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Article ID COMMUNITY STRUCTURE; FISH REMOVAL; BIOMANIPULATION; RESTORATION; BIOMASS AB Eutrophication of lakes, expressed as excess growth of planktonic algae, is caused by excessive inputs of phosphorus and can be mitigated by many mechanisms, including grazing. However, it has been hypothesized that grazing becomes ineffective with even modest increases in P input. We tested this contention directly by fertilizing lakes that had contrasting food webs. A lake with zooplanktivorous fishes and small grazers accumulated algal biomass as predicted by Vollenweider's model of eutrophication. A lake with piscivorous fishes and large grazers accumulated about half the algal biomass predicted by the model. However, blue-green algae bloomed in both lakes. Grazing may effectively control total algal biomass over a relatively wide range of P input rates, but may not suppress irruptions of nuisance algae. C1 INST ECOSYST STUDIES,MILLBROOK,NY 12545. NOAA,NATL MARINE FISHERIES SERV,HONOLULU,HI 96822. ST NORBERT COLL,DEPT BIOL,DE PERE,WI 54115. RP CARPENTER, SR (reprint author), UNIV WISCONSIN,CTR LIMNOL,680 N PK ST,MADISON,WI 53706, USA. RI Post, David/A-6987-2009; Cottingham, Kathryn/H-1593-2012; OI Post, David/0000-0003-1434-7729; Pace, Michael/0000-0001-5945-6131 NR 24 TC 90 Z9 97 U1 4 U2 46 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0013-936X J9 ENVIRON SCI TECHNOL JI Environ. Sci. Technol. PD MAR PY 1995 VL 29 IS 3 BP 784 EP 786 DI 10.1021/es00003a028 PG 3 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA QJ908 UT WOS:A1995QJ90800043 ER PT J AU LEVINE, JS COFER, WR CAHOON, DR WINSTEAD, EL AF LEVINE, JS COFER, WR CAHOON, DR WINSTEAD, EL TI BIOMASS BURNING - A DRIVER FOR GLOBAL CHANGE SO ENVIRONMENTAL SCIENCE & TECHNOLOGY LA English DT Article ID FOREST-FIRES; EMISSIONS C1 SCI APPLICAT INT CORP,GATS,HAMPTON,VA. RP LEVINE, JS (reprint author), NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA 23665, USA. NR 19 TC 48 Z9 53 U1 1 U2 21 PU AMER CHEMICAL SOC PI WASHINGTON PA PO BOX 57136, WASHINGTON, DC 20037-0136 SN 0013-936X J9 ENVIRON SCI TECHNOL JI Environ. Sci. Technol. PD MAR PY 1995 VL 29 IS 3 BP A120 EP A125 PG 6 WC Engineering, Environmental; Environmental Sciences SC Engineering; Environmental Sciences & Ecology GA QJ908 UT WOS:A1995QJ90800012 ER PT J AU AMBUR, DR PRASAD, CB WATERS, WA AF AMBUR, DR PRASAD, CB WATERS, WA TI A DROPPED-WEIGHT APPARATUS FOR LOW-SPEED IMPACT TESTING OF COMPOSITE STRUCTURES SO EXPERIMENTAL MECHANICS LA English DT Article AB A dropped-weight test apparatus has been developed that can be used to perform low-speed impact tests on composite aircraft structures. This vertical drop-weight test apparatus is simple, compact, inexpensive and has precision impact and self-arresting design features similar to the more sophisticated, expensive test machines. The test apparatus has been used to perform low-speed impact response studies on laminated composite plates to understand the influence of impactor and target parameters on structural response and to develop a validated analysis method. Some of the experimental results generated by using this test apparatus for composite laminated plates are presented in the present paper and compared with the corresponding analytical results. C1 ANALYT SERV & MAT INC,HAMPTON,VA 23666. LOCKHEED ENGN & SCI CO,HAMPTON,VA 23666. RP AMBUR, DR (reprint author), NASA,LANGLEY RES CTR,MS 190,HAMPTON,VA 23681, USA. NR 9 TC 9 Z9 9 U1 0 U2 3 PU SOC EXPERIMENTAL MECHANICS PI BETHEL PA 7 SCHOOL STREET, BETHEL, CT 06801 SN 0014-4851 J9 EXP MECH JI Exp. Mech. PD MAR PY 1995 VL 35 IS 1 BP 77 EP 82 DI 10.1007/BF02325839 PG 6 WC Materials Science, Multidisciplinary; Mechanics; Materials Science, Characterization & Testing SC Materials Science; Mechanics GA QR053 UT WOS:A1995QR05300013 ER PT J AU GAUDEMER, Y TAPPONNIER, P MEYER, B PELTZER, G GUO, SM CHEN, ZT DAI, HG CIFUENTES, I AF GAUDEMER, Y TAPPONNIER, P MEYER, B PELTZER, G GUO, SM CHEN, ZT DAI, HG CIFUENTES, I TI PARTITIONING OF CRUSTAL SLIP BETWEEN LINKED, ACTIVE FAULTS IN THE EASTERN QILIAN SHAN, AND EVIDENCE FOR A MAJOR SEISMIC GAP, THE TIANZHU GAP, ON THE WESTERN HAIYUAN FAULT, GANSU (CHINA) SO GEOPHYSICAL JOURNAL INTERNATIONAL LA English DT Article DE ACTIVE FAULTING; SEISMIC GAP; SLIP PARTITIONING; TIBET ID HUI AUTONOMOUS REGION; SAN-ANDREAS FAULT; MOMENT TENSOR SOLUTIONS; 10 OCTOBER 1980; SOUTHERN-CALIFORNIA; NORTHWEST CHINA; TRANSVERSE RANGES; LARGE EARTHQUAKES; TIBETAN PLATEAU; TECTONICS AB We have studied the Cenozoic and active tectonics of the north-eastern rim of Tibet west of the Yellow River (Gansu, China) where the western Haiyuan Fault enters the eastern Qilian Shan, a high mountainous region, which was the site of the 1927 May 23, M = 8-8.3, Gulang earthquake. Fieldwork, combined with analysis of aerial photographs and satellite images, reveals consistent cumulative left-lateral offsets of postglacial geomorphic features along the fault, but no recent rupture. West of the Tianzhu pull-apart basin, the levelling of offset-terrace risers implies Holocene horizontal and vertical slip rates on the steeply south-dipping, N110E-striking fault of 11 +/- 4 and 1.3 +/- 0.3 mm yr(-1), respectively. The presence of subordinate, mostly normal, throws due to local changes in fault strike, and kinematic compatibility at the SW corner of the Tianzhu basin, constrains the azimuth of the fault-slip vector to be N110-115E. On the less prominent, N85-100E-striking Gulang Fault, which splays eastwards from the Haiyuan Fault near 102.2 degrees E, less detailed observations suggest that the average Holocene left-slip rate is 4.3 +/- 2.1 mm yr(-1) with a minor component of approximate to N-directed thrusting, with no recent seismic break either. East of approximate to 103 degrees E, coeval slip on both faults thus appears to account for as much as 15 +/- 6 mm yr(-1) of left-lateral movement between NE Tibet and the southern edge of the Ala Shan Platform, in a N105 +/- 6E direction. West of approximate to 103 degrees E, structural and geomorphic evidence implies that approximate to NNE-directed shortening of that edge across the rising, north-eastern Qilian mountain ranges occurs at a rate of 4 +/- 2 mm yr(-1), by movement on right-stepping thrusts that root on a 10-20 degrees S-dipping decollement that probably branches off the Haiyuan Fault at a depth of approximate to 25 km. The existence of fresh surface breaks with metre-high free faces on a N-dipping, hanging-wall normal fault south of the easternmost, Dongqingding thrust segment, and of half-metre-high pressure ridges on that segment, indicates that the 1927 Gulang earthquake ruptured that complex thrust system. The approximate to 4 mm yr(-1) shortening rate is consistent with the inference that the thrusts formed and move as a result of orthogonal slip partitioning in a large restraining bend of the Haiyuan Fault. Based on a retrodeformable structural section, we estimate the cumulative shortening on the Qilian Shan thrusts, north of the Haiyuan Fault, to be at least 25 km. The finite displacements and current slip rates on either the thrusts or the left-lateral faults imply that Cenozoic deformation started in the Late Miocene, with slip partitioning during much of the Plio-Quaternary. Assuming coeval slip at the present rates on the Haiyuan and Gulang Faults in the last 8 Ma would bring the cumulative left-lateral displacement between NE Tibet and the Ala Shan Platform to about 120 km, consistent with the 95 +/- 15 km offset of the Yellow River across the Haiyuan Fault, but many times the offset (approximate to 16 km) inferred on one recent strand of that fault east of the river. Relative to the SE Gobi Desert, NE Tibet thus appears to have moved by a fair amount in the Late Cenozoic and is still moving fast. While some of this motion probably contributes to displace (towards the ESE) and rotate (CCW) the south-west edge of the Ordos block, much of it appears to be transmitted to the South China block, which leads, with the additional contribution of other large left-slip faults to the south and despite thrusting in the Lungmen Shan, to the extrusion (towards the ESE-SE) of that block relative to the Gobi, hence to north-eastern Asia. The approximate to 260 km long western Haiyuan Fault links two faults that ruptured about 70 years ago during two great earthquakes only seven years apart. Despite spectacular evidence of Holocene movement, it bears no trace of a large earthquake in the past eight centuries, either in the field or in the historical record. Given its relatively high slip rate, it should therefore be singled out as one of the most critical sites for impending great earthquakes (at least M greater than or equal to 7.5, probably M greater than or equal to 8) in the region. That such a seismic gap, called here the 'Tianzhu gap', lies only approximate to 100 km north of Lanzhou and Xining, largest population centres of west-central China, makes instrumental monitoring of that fault particularly urgent. That the M approximate to 8, Gulang earthquake ruptured a complex thrust surface under high mountains in a restraining bend of the Haiyuan strike-slip fault suggests that the occurrence of comparable earthquakes in other areas with similar fault geometry, such as south of the big bend of the San Andreas Fault in California, should not be ruled out. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. STATE SEISMOL BUR,INST GEOL,BEIJING 100029,PEOPLES R CHINA. SEISMOL INST LANZHOU,INST GEOL,LANZHOU,PEOPLES R CHINA. CARNEGIE INST WASHINGTON,DEPT TERR MAGNETISM,WASHINGTON,DC 20025. RP GAUDEMER, Y (reprint author), INST PHYS GLOBE,TECTON LAB,4 PL JUSSIEU,F-75252 PARIS 05,FRANCE. RI Tapponnier, .Paul/B-7033-2011; Gaudemer, Yves/K-3921-2012; Meyer, Bertrand/E-6903-2011 OI Tapponnier, .Paul/0000-0002-7135-1962; NR 92 TC 151 Z9 189 U1 2 U2 14 PU BLACKWELL SCIENCE LTD PI OXFORD PA OSNEY MEAD, OXFORD, OXON, ENGLAND OX2 0EL SN 0956-540X J9 GEOPHYS J INT JI Geophys. J. Int. PD MAR PY 1995 VL 120 IS 3 BP 599 EP 645 DI 10.1111/j.1365-246X.1995.tb01842.x PG 47 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QK634 UT WOS:A1995QK63400007 ER PT J AU JOUGHIN, IR WINEBRENNER, DP FAHNESTOCK, MA AF JOUGHIN, IR WINEBRENNER, DP FAHNESTOCK, MA TI OBSERVATIONS OF ICE-SHEET MOTION IN GREENLAND USING SATELLITE RADAR INTERFEROMETRY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB We present interferometric observations of ice-sheet motion in western Greenland based on pairs of ERS-1 synthetic aperture radar (SAR) images. These observations provide the first detailed regional view of ice motion associated with dynamically supported topography near the margin of an ice sheet. The interferograms of this area are much more complicated than other interferograms of ice sheets presented to date. We devote the largest part of this paper to explaining the source of the complexity in these interferograms. A synthetic interferogram based on a simple model helps to illustrate the effects of different components of the ice velocity held in interferometric data and suggests a method for estimating the large-scale ice velocity field from such data. C1 NASA,GODDARD SPACE FLIGHT CTR,USRA,GREENBELT,MD 20771. RP JOUGHIN, IR (reprint author), UNIV WASHINGTON,CTR POLAR SCI,APPL PHYS LAB,1013 NE 40TH ST,SEATTLE,WA 98105, USA. RI Joughin, Ian/A-2998-2008; Fahnestock, Mark/N-2678-2013 OI Joughin, Ian/0000-0001-6229-679X; NR 14 TC 53 Z9 59 U1 0 U2 3 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 1 PY 1995 VL 22 IS 5 BP 571 EP 574 DI 10.1029/95GL00264 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QL415 UT WOS:A1995QL41500012 ER PT J AU RIGNOT, E JEZEK, EC SOHN, HG AF RIGNOT, E JEZEK, EC SOHN, HG TI ICE FLOW DYNAMICS OF THE GREENLAND ICE-SHEET FROM SAR INTERFEROMETRY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SATELLITE RADAR INTERFEROMETRY; MASS BALANCE AB Synthetic-aperture radar (SAR) interferograms produced from ESA's ERS-1 satellite, provide the first synoptic view of ice flow dynamics of the western sector of the Greenland Ice Sheet. Glacial motion is detected in the radar ranging direction at millimetric scales, across a complete sequence of snow accumulation and melting regimes, despite significant variations in their radar scattering properties. Ice flow evolves from a slow, regular motion at the higher elevations. At lower elevations, motion is strongly convoluted by meter-scale undulations in surface topography, which have a unique interferometric signature that enables a novel approach for retrieving flow direction. Inferred flow directions, combined with surface displacements in the radar ranging direction, yield ice velocity estimates that are within 6% of in-situ measurements gathered along a 40 km survey line. Application of repeat-pass SAR interferometry to the entire Greenland Ice Sheet should enable precise mapping of its ice flow dynamics at an unprecedented level of spatial detail. C1 OHIO STATE UNIV,BYRD POLAR RES CTR,COLUMBUS,OH 43210. RP RIGNOT, E (reprint author), CALTECH,JET PROP LAB,MS 300-243,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Sohn, Hong gyoo/G-8899-2012; Rignot, Eric/A-4560-2014 OI Rignot, Eric/0000-0002-3366-0481 NR 17 TC 41 Z9 43 U1 1 U2 6 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAR 1 PY 1995 VL 22 IS 5 BP 575 EP 578 DI 10.1029/94GL03381 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QL415 UT WOS:A1995QL41500013 ER PT J AU ECK, TF BHARTIA, PK KERR, JB AF ECK, TF BHARTIA, PK KERR, JB TI SATELLITE ESTIMATION OF SPECTRAL UVB IRRADIANCE USING TOMS DERIVED TOTAL OZONE AND UV REFLECTIVITY SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ULTRAVIOLET-B RADIATION; COMPARISON EXPERIMENT-1; SOLAR; CLOUDS; TRENDS AB A method for satellite remote sensing of spectral UVB radiation incident at the earth's surface for snow and/or ice free areas has been developed. Measurements of total ozone and UV reflectivity from the Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) instrument have been applied to this technique. Comparison of satellite estimates with ground based measurements of spectral UVB irradiance show differences which are comparable to differences between near simultaneous measurements made with two or more ground based co-located instruments. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. ENVIRONM CANADA,ATMOSPHER ENVIRONM SERV,DOWNSVIEW,ON M3H 5T4,CANADA. RP ECK, TF (reprint author), HUGHES STX CORP,LANHAM,MD, USA. RI ECK, THOMAS/D-7407-2012; Bhartia, Pawan/A-4209-2016 OI Bhartia, Pawan/0000-0001-8307-9137 NR 18 TC 117 Z9 119 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD MAR 1 PY 1995 VL 22 IS 5 BP 611 EP 614 DI 10.1029/95GL00111 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QL415 UT WOS:A1995QL41500022 ER PT J AU CARGILL, PJ CHEN, J SPICER, DS ZALESAK, ST AF CARGILL, PJ CHEN, J SPICER, DS ZALESAK, ST TI GEOMETRY OF INTERPLANETARY MAGNETIC CLOUDS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID MAGNETOSPHERE; TOPOLOGY; FIELDS; STORMS AB Two dimensional magnetohydrodynamic simulations are presented of the distortion of a magnetic flux rope that is being accelerated through ambient solar wind plasma. The flux rope magnetic field has an axial component parallel to the solar wind field and an azimuthal component, which lies in the simulation plane. As the flux rope moves through the solar wind plasma, vortices form on its trailing edge and couple strongly to its interior. If the flux rope azimuthal field is weak, it deforms into an elongated banana-like shape after a few Alfven transit times. A strong azimuthal field component tends to inhibit this distortion. If the flux rope is taken to model a magnetic cloud, it is suggested that the shape of the cloud at 1 AU is determined by its distortion in the inner solar wind. Distortion timescales beyond 1 AU are estimated as many days. It is estimated that effective drag coefficients somewhat greater than unity are appropriate for modelling flux rope propagation. C1 NASA,GODDARD SPACE FLIGHT CTR,CTR COMPUTAT SCI,GREENBELT,MD 20771. RP CARGILL, PJ (reprint author), USN,RES LAB,DIV PLASMA PHYS,BEAM PHYS BRANCH,CODE 6790,WASHINGTON,DC 20375, USA. NR 18 TC 28 Z9 28 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 MAR 1 PY 1995 VL 22 IS 5 BP 647 EP 650 DI 10.1029/95GL00013 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QL415 UT WOS:A1995QL41500031 ER PT J AU LEAN, JL MARISKA, JT STRONG, KT HUDSON, HS ACTON, LW ROTTMAN, GJ WOODS, TN WILLSON, RC AF LEAN, JL MARISKA, JT STRONG, KT HUDSON, HS ACTON, LW ROTTMAN, GJ WOODS, TN WILLSON, RC TI CORRELATED BRIGHTNESS VARIATIONS IN SOLAR RADIATIVE OUTPUT FROM THE PHOTOSPHERE TO THE CORONA SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID IRRADIANCE COMPARISON EXPERIMENT-1; LUMINOSITY; INSTRUMENT; MISSION; NETWORK; LINE; SUN AB Correlated brightness variations are shown to occur in time series of coronal soft X-rays exclusive of prominent active regions, chromospheric ultraviolet radiation, and the photospheric total solar irradiance corrected for sunspot effects. These temporal correlations suggest that upwardly extending magnetic fields may have a large scale impact on the solar atmosphere in addition to their demonstrable role of generating localized active regions. The correlations have implications for improving and extending solar spectrum variability models. C1 LOCKHEED PALO ALTO RES LABS,PALO ALTO,CA 94304. UNIV HAWAII,HONOLULU,HI 96822. MONTANA STATE UNIV,BOZEMAN,MT 59717. NATL CTR ATMOSPHER RES,HIGH ALTITUDE OBSERV,BOULDER,CO 80307. JET PROPULS LAB,PASADENA,CA. RP LEAN, JL (reprint author), USN,RES LAB,EO HULBURT CTR SPACE RES,CODE 7673L,WASHINGTON,DC 20375, USA. NR 29 TC 7 Z9 8 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 MAR 1 PY 1995 VL 22 IS 5 BP 655 EP 658 DI 10.1029/95GL00114 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QL415 UT WOS:A1995QL41500033 ER PT J AU TOON, OB ZAHNLE, K AF TOON, OB ZAHNLE, K TI ALL IMPACTS GREAT AND SMALL SO GEOTIMES LA English DT Article DE IMPACTS RP TOON, OB (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOLOGICAL INST PI ALEXANDRIA PA 4220 KING ST, ALEXANDRIA, VA 22302-1507 SN 0016-8556 J9 GEOTIMES JI Geotimes PD MAR PY 1995 VL 40 IS 3 BP 21 EP 23 PG 3 WC Geosciences, Multidisciplinary SC Geology GA QK569 UT WOS:A1995QK56900006 ER PT J AU RAICH, JW POTTER, CS AF RAICH, JW POTTER, CS TI GLOBAL PATTERNS OF CARBON-DIOXIDE EMISSIONS FROM SOILS SO GLOBAL BIOGEOCHEMICAL CYCLES LA English DT Review ID FOREST ECOSYSTEM PROCESSES; MIXED DECIDUOUS FOREST; CO2 EVOLUTION; GENERAL-MODEL; MICROBIAL DECOMPOSITION; REGIONAL APPLICATIONS; SPATIAL VARIABILITY; TROPICAL GRASSLAND; SEASONAL PATTERN; VEGETATION INDEX AB We use semi-mechanistic, empirically based statistical models to predict the spatial and temporal patterns of global carbon dioxide emissions from terrestrial soils. Emissions include the respiration of both soil organisms and plant roots. At the global scale, rates of soil CO2 efflux correlate significantly with temperature and precipitation; they do not correlate well with soil carbon pools, soil nitrogen pools, or soil C:N. Wetlands cover about 3% of the land area but diminish predicted CO2 emissions by only about 1%. The estimated annual flux of CO2 from soils to the atmosphere is estimated to be 76.5 Pg C yr(-1) 1-9 Pg greater than previous global estimates, and 30-60 greater than terrestrial net primary productivity. Historic land cover changes are estimated to have reduced current annual soil CO2 emissions by 0.2-2.0 Pg C yr(-1) in comparison with an undisturbed vegetation cover. Soil CO2 fluxes have a pronounced seasonal pattern in most locations, with maximum emissions coinciding with periods of active plant growth. Our models suggest that soils produce CO2 throughout the year and thereby contribute to the observed wintertime increases in atmospheric CO2 concentrations. Our derivation of statistically based estimates of soil CO2 emissions at a 0.5 degrees latitude by longitude spatial and monthly temporal resolution represents the best-resolved estimate to date of global CO2 fluxes from soils and should facilitate investigations of net carbon exchanges between the atmosphere and terrestrial biosphere. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP RAICH, JW (reprint author), IOWA STATE UNIV SCI & TECHNOL,DEPT BOT,353 BESSY HALL,AMES,IA 50011, USA. NR 125 TC 556 Z9 805 U1 16 U2 246 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0886-6236 J9 GLOBAL BIOGEOCHEM CY JI Glob. Biogeochem. Cycle PD MAR PY 1995 VL 9 IS 1 BP 23 EP 36 DI 10.1029/94GB02723 PG 14 WC Environmental Sciences; Geosciences, Multidisciplinary; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Geology; Meteorology & Atmospheric Sciences GA RB220 UT WOS:A1995RB22000003 ER PT J AU RUBINCAM, DP CHAO, BF THOMAS, PC AF RUBINCAM, DP CHAO, BF THOMAS, PC TI THE GRAVITATIONAL-FIELD OF DEIMOS SO ICARUS LA English DT Article ID PHOBOS; SATELLITES; GRAVITY; SURFACE AB Deimos may be largely uniform in density. We find here the gravitational field of Deimos and its moments of inertia from the moon's shape and an assumed uniform density distribution, From these data we compute the expected orientation, The orientation of the model Deimos relative to Mars agrees with that observed to within the observation uncertainties (a few degrees), Hence Deimos may be homogeneous and not have significant density variations in its interior, We also find that the spherical harmonic coefficient J(2) is about 0.108 for the model, so that Deimos is about as gravitationally flattened as Phobos, whose J(2) is about 0.105. (C) 1995 Academic Press, Inc. C1 CORNELL UNIV,CTR RADIOPHYS & SPACE RES,ITHACA,NY 14853. RP RUBINCAM, DP (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GEODYNAM BRANCH,GREENBELT,MD 20771, USA. RI Rubincam, David/D-2918-2012; Chao, Benjamin Fong/N-6156-2013 NR 13 TC 8 Z9 8 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAR PY 1995 VL 114 IS 1 BP 63 EP 67 DI 10.1006/icar.1995.1043 PG 5 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ324 UT WOS:A1995QQ32400005 ER PT J AU GRIEVE, RAF CINTALA, MJ AF GRIEVE, RAF CINTALA, MJ TI IMPACT MELTING ON VENUS - SOME CONSIDERATIONS FOR THE NATURE OF THE CRATERING RECORD SO ICARUS LA English DT Article ID TERRESTRIAL IMPACT; VOLCANIC ORIGIN; MAGELLAN; LUNAR; EMPLACEMENT; MECHANICS; OUTFLOWS; RADAR AB Modeling the volume of impact melt and its variation with the size of the impact event indicates that, for similar-sized final craters, venusian impacts create about 25% more impact melt than terrestrial impacts. More significantly, venusian impacts result in approximately a factor of three more impact melt than lunar events producing equivalent-sized craters. This difference is due to the higher average impact velocity and higher ambient temperatures on Venus, which enhance impact-melt production, combined with higher planetary gravity, which inhibits crater growth for a given impact event. The initial, higher intrinsic temperature of incorporated elastic debris also contributes to impact melts with higher initial temperatures, lower viscosities, and longer cooling times on Venus with respect to lunar impact melts. The enhanced production of relatively hot, low-viscosity impact melts under venusian impact conditions may account for the long exterior runout flows and also for the radar-smooth interior doors of some venusian craters. We also argue that the anomalously deep character of Cleopatra may be attributed to drainage of its interior impact-melt pool to form the smooth deposits in the adjacent Fortuna Tessera. Increasing depth of melting with increasing cavity size, resulting in the progressive weakening of transient-cavity floor material, is offered as a possible explanation for the replacement of uplifted central peaks by rings with increasing crater diameter. A consequence of this process is that interior rings will increase in diameter relative to the diameter of the final crater's rim crest with increasing crater size, a trend observed on Venus and other terrestrial planets. This weakening of the target due to relatively enhanced impact-melt production in the venusian environment makes it unlikely that Orientale-style impact basins ever formed on Venus. (C) 1995 Academic Press, Inc. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP GRIEVE, RAF (reprint author), GEOL SURVEY CANADA,601 BOOTH ST,OTTAWA,ON K1A OY3,CANADA. NR 70 TC 12 Z9 12 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAR PY 1995 VL 114 IS 1 BP 68 EP 79 DI 10.1006/icar.1995.1044 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ324 UT WOS:A1995QQ32400006 ER PT J AU ZUBER, MT AF ZUBER, MT TI WRINKLE RIDGES, REVERSE FAULTING, AND THE DEPTH PENETRATION OF LITHOSPHERIC STRAIN IN LUNAE-PLANUM, MARS SO ICARUS LA English DT Article ID TERRESTRIAL PLANETS; THARSIS PLATEAU; THICKNESS; REGION; STRESS; ORIGIN; ORIENTATION; TECTONICS; GRAVITY; SUPPORT AB Wrinkle ridges in the Lunae Planum region of Mars formed in response to compressional stresses associated with the development of the Tharsis rise. In this study, we investigate the accomodation of lithospheric strain associated with wrinkle ridge development in order to constrain the depth penetration of deformation associated with the formation of Tharsis. Using observations that indicate that the shallow martian lithosphere in Lunae Planum consists of a surface plains unit underlain successively by an unconsolidated megaregolith and competent basement, we construct models of an elastic lithosphere in which a ridge nucleates along a single fault in either the surface plains unit or basement. We then calculate strain and displacement fields for a range of plausible lithosphere structures assuming uniform horizontal shortening of the lithosphere. Transmission of strain between the surface layer and basement is most effective for a thin megaregolith and small Young's modulus contrast between the surface layer, megaregolith, and basement. However, results under a broad range of conditions for both models show straining of both the surface layer and basement. If lithosphere structure information and strains estimated by kinematic studies of the wrinkle ridges are applicable, then Tharsis-related compressional deformation must have involved the lithosphere, rather than being restricted to the near-surface. (C) 1995 Academic Press, Inc. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP ZUBER, MT (reprint author), JOHNS HOPKINS UNIV,DEPT EARTH & PLANETARY SCI,BALTIMORE,MD 21218, USA. NR 51 TC 20 Z9 20 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAR PY 1995 VL 114 IS 1 BP 80 EP 92 DI 10.1006/icar.1995.1045 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ324 UT WOS:A1995QQ32400007 ER PT J AU COURTIN, R GAUTIER, D AF COURTIN, R GAUTIER, D TI TITANS THERMAL EMISSION-SPECTRUM - REANALYSIS OF THE VOYAGER INFRARED MEASUREMENTS SO ICARUS LA English DT Article ID ROTOTRANSLATIONAL ABSORPTION-SPECTRA; HYPOTHESIZED OCEAN; RADIO-OCCULTATION; WATER ICE; ATMOSPHERE; METHANE; PAIRS; TEMPERATURE; MIXTURES; SURFACE AB We have modeled the far-infrared spectrum of Titan between 200 and 600 cm(-1), including the fine structure of the H-2-N-2 and H-2-CH4 dimers around 355 and 585 cm(-1) respectively. A selection of 373 Voyager IRIS spectra recorded at low and mid-latitudes provides the observational basis for our analysis. The opacity model is significantly improved over previous work by taking into account recent ab initio calculations of the collision-induced absorption by N-2-CH4 pairs, as well as laboratory measurements of the H-2-N-2 dimer transitions. In addition to the collision-induced gaseous absorption, the radiative transfer model includes scattering and absorption by stratospheric haze particles and potential tropospheric condensation clouds. We investigate the possible presence of argon, mainly through its influence on the thermal profile retrieved from the Voyager radiooccultation measurements. We find the following results: (1) The observations are best fit with significant methane supersaturation in the troposphere (up to a factor of two) and no condensation cloud present. (2) If a condensation cloud is present we find that it must have an optical depth less than 0.7 with a mean particle radius of about 50 mu m and be located very near the minimum temperature level around 40 km, significantly higher than the expected condensation level. (3) In any case, the CH4 mole fraction at the cold trap is 0.017-0.045, the H-2 mole fraction is 1.0 +/- 0.4 x 10(-3), the argon mole fraction is Less than 0.06 (3 sigma), and the imaginary index of refraction of the haze material at 600 cm(-1) is 30-80% that of tholins. (C) 1995 Academic Press, Inc. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP COURTIN, R (reprint author), OBSERV PARIS,DEPT RECH SPATIALE,CNRS,URA 264,F-92195 MEUDON,FRANCE. NR 56 TC 109 Z9 109 U1 1 U2 10 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAR PY 1995 VL 114 IS 1 BP 144 EP 162 DI 10.1006/icar.1995.1050 PG 19 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ324 UT WOS:A1995QQ32400012 ER PT J AU VEEDER, GJ MATSON, DL OWENSBY, PD GRADIE, JC BELL, JF TEDESCO, EF AF VEEDER, GJ MATSON, DL OWENSBY, PD GRADIE, JC BELL, JF TEDESCO, EF TI EOS, KORONIS, AND MARIA FAMILY ASTEROIDS - INFRARED (JHK) PHOTOMETRY SO ICARUS LA English DT Article ID TAXONOMY AB Infrared photometry at 1.2, 1.6, and 2.2 mu m (JHK) is reported for 56 asteroids in the Eos, Koronis and, Maria dynamical families. These data are consistent with a similar surface composition for all of the asteroids of each family. The infrared colors within each family cluster in the region observed for the S taxonomic class, but Eos asteroids may belong to a separable K class. Asteroid 243 Ida, which was observed by the Galileo spacecraft, is a typical member of the Koronis family. The average infrared colors of the Maria family are slightly redder than those of the Eos and Koronis families. (C) 1995 Academic Press, Inc. C1 SETS TECHNOL INC,MILILANI,HI 96789. TERRA SYST INC,KAILUA,HI 96734. UNIV HAWAII MANOA,DIV PLANETARY GEOSCI,HONOLULU,HI 96822. MISSION RES CORP,NASHUA,NH 03062. RP VEEDER, GJ (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 67 TC 13 Z9 13 U1 0 U2 0 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0019-1035 J9 ICARUS JI Icarus PD MAR PY 1995 VL 114 IS 1 BP 186 EP 196 DI 10.1006/icar.1995.1053 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QQ324 UT WOS:A1995QQ32400015 ER PT J AU HUSSAINI, MY AF HUSSAINI, MY TI ICASE - NASA LANGLEYS CSE CENTER SO IEEE COMPUTATIONAL SCIENCE & ENGINEERING LA English DT Article RP HUSSAINI, MY (reprint author), NASA,LANGLEY RES CTR,ICASE,MAIL STOP 132C,HAMPTON,VA 23681, USA. NR 0 TC 1 Z9 1 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 1070-9924 J9 IEEE COMPUT SCI ENG JI IEEE Comput. Sci. Eng. PD SPR PY 1995 VL 2 IS 1 BP 6 EP 14 DI 10.1109/99.372925 PG 9 WC Computer Science, Theory & Methods; Engineering, Electrical & Electronic; Mathematics, Applied SC Computer Science; Engineering; Mathematics GA RB249 UT WOS:A1995RB24900002 ER PT J AU CHOU, JJ AF CHOU, JJ TI VORONOI DIAGRAMS FOR PLANAR SHAPES SO IEEE COMPUTER GRAPHICS AND APPLICATIONS LA English DT Article ID ALGORITHM; SET RP CHOU, JJ (reprint author), NASA,AMES RES CTR,COMP SCI CORP,M-S T27B-2,MOFFETT FIELD,CA 94035, USA. NR 12 TC 32 Z9 34 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0272-1716 J9 IEEE COMPUT GRAPH JI IEEE Comput. Graph. Appl. PD MAR PY 1995 VL 15 IS 2 BP 52 EP 59 DI 10.1109/38.365006 PG 8 WC Computer Science, Software Engineering SC Computer Science GA QJ144 UT WOS:A1995QJ14400010 ER PT J AU LIN, TL GUNAPALA, SD JONES, EW DELCASTILLO, HM WEEKS, MM PELLEGRINI, PW AF LIN, TL GUNAPALA, SD JONES, EW DELCASTILLO, HM WEEKS, MM PELLEGRINI, PW TI 7-MU-M-CUTOFF PTSI INFRARED DETECTOR FOR HIGH-SENSITIVITY MWIR APPLICATIONS SO IEEE ELECTRON DEVICE LETTERS LA English DT Article AB PtSi Schottky Infrared detectors with extended cut-off wavelengths of 5.7, 6.6, and 7.3 mum have been demonstrated by incorporating a thin p+ layer at the PtSi/Si interface for high sensitivity medium wavelength infrared imaging applications. The response uniformity of the 7-mum cutoff detector was studied. C1 ROME LAB,BEDFORD,MA 01731. RP LIN, TL (reprint author), JET PROP LAB,CTR SPACE & MICROELECTR TECHNOL,PASADENA,CA 91109, USA. NR 6 TC 17 Z9 21 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0741-3106 J9 IEEE ELECTR DEVICE L JI IEEE Electron Device Lett. PD MAR PY 1995 VL 16 IS 3 BP 94 EP 96 DI 10.1109/55.363236 PG 3 WC Engineering, Electrical & Electronic SC Engineering GA QJ279 UT WOS:A1995QJ27900004 ER PT J AU KORMANYOS, BK REBEIZ, GM AF KORMANYOS, BK REBEIZ, GM TI OSCILLATOR DESIGN FOR MAXIMUM ADDED POWER (VOL 4, PG 205, 1994) SO IEEE MICROWAVE AND GUIDED WAVE LETTERS LA English DT Correction, Addition RP KORMANYOS, BK (reprint author), UNIV MICHIGAN,NASA,CTR SPACE TERAHERTZ TECHNOL,DEPT ELECT ENGN & COMP SCI,ANN ARBOR,MI 48109, USA. NR 0 TC 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 1051-8207 J9 IEEE MICROW GUIDED W JI IEEE Microw. Guided Wave Lett. PD MAR PY 1995 VL 5 IS 3 BP 93 EP 93 PG 1 WC Engineering, Electrical & Electronic SC Engineering GA QJ535 UT WOS:A1995QJ53500008 ER PT J AU LEON, M AF LEON, M TI ESTABLISHING A REAL-TIME VIDEO LINK TO ANTARCTICA SO IEEE NETWORK LA English DT Article C1 NASA,IITAK12 PROGRAM,MOFFETT FIELD,CA 94035. RP LEON, M (reprint author), NASA,AMES RES CTR,INFORMAT INFRASTRUCT TECHNOL & APPLICAT PROJECT,MOFFETT FIELD,CA 94035, USA. NR 0 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 0890-8044 J9 IEEE NETWORK JI IEEE Netw. PD MAR-APR PY 1995 VL 9 IS 2 BP 8 EP 15 DI 10.1109/65.372651 PG 8 WC Computer Science, Hardware & Architecture; Computer Science, Information Systems; Engineering, Electrical & Electronic; Telecommunications SC Computer Science; Engineering; Telecommunications GA QN197 UT WOS:A1995QN19700002 ER PT J AU MARTIN, RD FOROUHAR, S KEO, S LANG, RJ HUNSPERGER, RG TIBERIO, RC CHAPMAN, PF AF MARTIN, RD FOROUHAR, S KEO, S LANG, RJ HUNSPERGER, RG TIBERIO, RC CHAPMAN, PF TI CW PERFORMANCE OF AN INGAAS-GAAS-ALGAAS LATERALLY-COUPLED DISTRIBUTED-FEEDBACK (LC-DFB) RIDGE LASER-DIODE SO IEEE PHOTONICS TECHNOLOGY LETTERS LA English DT Article AB Single-mode distributed feedback (DFB) laser diodes typically require a two-step epitaxial growth or use of a corrugated substrate. We demonstrate InGaAs-GaAs-AlGaAs DFB lasers fabricated from a single epitaxial growth using lateral evanescent coupling of the optical field to a surface grating etched along the sides of the ridge, A CW threshold current of 25 mA and external quantum: efficiency of 0.48 mW/mA per facet were measured for a 1 mm cavity length device with anti-reflection coated facets. Single-mode output powers as high as 11 mW per facet at 935 nm wavelength were attained, A coupling coefficient of at least 5.8 cm(-1) was calculated from the subthreshold spectrum taking into account the 2% residual facet reflectivity. C1 CALTECH,JET PROP LAB,CTR SPACE MICROELECTR TECHNOL,PASADENA,CA 91109. CORNELL UNIV,NATL NANOFABRICAT FACIL,ITHACA,NY 14853. RP MARTIN, RD (reprint author), UNIV DELAWARE,DEPT ELECT ENGN,NEWARK,DE 19716, USA. NR 11 TC 64 Z9 64 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 1041-1135 J9 IEEE PHOTONIC TECH L JI IEEE Photonics Technol. Lett. PD MAR PY 1995 VL 7 IS 3 BP 244 EP 246 DI 10.1109/68.372734 PG 3 WC Engineering, Electrical & Electronic; Optics; Physics, Applied SC Engineering; Optics; Physics GA QM580 UT WOS:A1995QM58000006 ER PT J AU TAUSWORTHE, RC AF TAUSWORTHE, RC TI EXPERIENCE MORE RELIABLE THAN THEORY AT 5TH ISSRE SO IEEE SOFTWARE LA English DT Article RP TAUSWORTHE, RC (reprint author), JET PROPULS LAB,PASADENA,CA, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU IEEE COMPUTER SOC PI LOS ALAMITOS PA 10662 LOS VAQUEROS CIRCLE, PO BOX 3014, LOS ALAMITOS, CA 90720-1264 SN 0740-7459 J9 IEEE SOFTWARE JI IEEE Softw. PD MAR PY 1995 VL 12 IS 2 BP 110 EP 111 PG 2 WC Computer Science, Software Engineering SC Computer Science GA QL330 UT WOS:A1995QL33000025 ER PT J AU IMHOFF, ML AF IMHOFF, ML TI A THEORETICAL-ANALYSIS OF THE EFFECT OF FOREST STRUCTURE ON SYNTHETIC-APERTURE RADAR BACKSCATTER AND THE REMOTE-SENSING OF BIOMASS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID MODEL; BAND; SAR; VEGETATION; STANDS AB Stand level forest canopy structure as measured by the size, density, and distribution of the stems, branches, and leaves may have a strong effect on SAR backscatter. This study used the Michigan Microwave Canopy Scattering model (MIMICS) and forest canopy biometric data from tropical and subtropical broadleaf forests to simulate a series of forest stands having equivalent above ground biomass while still exhibiting substantial structural differences. The model stands were made to represent a wide range of basic structural differences found in Earth's broadleaf forests. The radar response to these structural differences is shown for the NASA/JPL AIRSAR P-, L-, and C-band quadpol, configuration at incidence angles of 20 degrees, 40 degrees, and 60 degrees, Results for three sets of equal-biomass-forest-stands were generated: five structural types having a total above ground biomass of 5 kg/m(2) (50 ton/ha), three structural types at 15 kg/m(2) (150 tons/ha), and three structural types at 30 kg/m(2) (300 tons/ha). Simplified model input were used to reduce the number of geometric variables tested across the range of structural types, The potential effect that extreme structural differences might have on the biomass signal and saturation threshold was assessed. Results indicate that structure can have a considerable effect on the SAR return for forests with equivalent above ground biomass, Differences in backscatter of up to 18 dB were predicted for some bands and polarizations. A forest canopy structural descriptor derived from the vegetation surface area to volume ratio (SA/V), which is a measure of stuctural consolidation, appears to explain the differences in backscatter. In many vegetation stands structural consolidation is directly related to an increase in biomass during the ''thinning phase'' of forest succession. This structural effect may explain the good relationship between SAR backscatter and biomass in these cases. RP IMHOFF, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771, USA. NR 44 TC 110 Z9 114 U1 1 U2 11 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1995 VL 33 IS 2 BP 341 EP 352 DI 10.1109/36.377934 PG 12 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA QN940 UT WOS:A1995QN94000012 ER PT J AU SUN, GQ RANSON, KJ AF SUN, GQ RANSON, KJ TI A 3-DIMENSIONAL RADAR BACKSCATTER MODEL OF FOREST CANOPIES SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID TEXTURAL INFORMATION; VEGETATION; BIOMASS; IMAGES; LAYER AB A three-dimensional forest backscatter model, which takes full account of spatial position of trees in a forest stand is described. A forest stand was divided into cells according to arbitrary spatial resolution. The cells may include ''crown,'' ''trunk'', and ''gap'' components, determined by the shape, size and position of the trees, The forest floor is represented by a layer of ''ground'' cells. A ray tracing method was used to calculate backscattering components of 1) direct crown backscatter, 2) direct backscattering from ground, 3) direct backscattering from trunk, 4) crown-ground scattering, and 5) trunk-ground scattering. Both the attenuation and time-delay of microwave signals within cells other than ''gap'' were also calculated from ray tracing. The backscattering Mueller matrices of these components within the same range intervals were incoherently added to yield the total backscattering of an image pixel. By assuming a zero-mean, multiplicative Gaussian noise for image speckle, the high-resolution images were aggregated to simulate a SAR image with a given spatial resolution and number of independent samples (looks). A well-characterized 150 m x 200 m forest stand in Maine, USA, was used to parameterize the model. The simulated radar backscatter coefficients were compared with actual JPL SAR data. The model gives reasonable prediction of backscattering coefficients averaged over the entire stand with agreement between model and data within 1.35 dB for all channels, The correlations between simulated images and SAR data (10 by 15 pixels) were positive and significant at the 0.001 level for all frequencies (P, L, and C bands) and polarizations (HH, HV, and VV). C1 NASA, GODDARD SPACE FLIGHT CTR, BIOSPHER SCI BRANCH, GREENBELT, MD 20771 USA. RP SUN, GQ (reprint author), SCI SYST & APPLICAT INC, LANHAM, MD 20706 USA. RI Ranson, Kenneth/G-2446-2012 OI Ranson, Kenneth/0000-0003-3806-7270 NR 29 TC 81 Z9 95 U1 1 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0196-2892 EI 1558-0644 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1995 VL 33 IS 2 BP 372 EP 382 PG 11 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA QN940 UT WOS:A1995QN94000015 ER PT J AU MADSEN, SN MARTIN, JM ZEBKER, HA AF MADSEN, SN MARTIN, JM ZEBKER, HA TI ANALYSIS AND EVALUATION OF THE NASA/JPL TOPSAR ACROSS-TRACK INTERFEROMETRIC SAR SYSTEM SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID SYNTHETIC APERTURE RADARS AB We have evaluated the accuracy of digital elevation models (DEM's) generated by the JPL/NASA TOPSAR synthetic aperture radar interferometer instrument by acquiring topographic radar data in the summer of 1992 over the National Training Center, near Ft. Irwin, California, and comparing the measurements to a very accurate digital elevation model derived for this area by the U.S. Army Topographic Engineering Center (TEC). Fiducial corner reflectors were deployed in the area, and their locations were determined to cm accuracy by the Defense Mapping Agency (DMA). DEM's generated from the acquired radar data were rotated and translated to precisely overlay the reference DEM, allowing an analysis of the achieved height accuracy. We present here a detailed description of horizontal and vertical errors and their characteristics. The standard deviation measured over a 5.6 x 7 km area was approximately 2 m, the corresponding figures for relatively hat areas were in the 1-2 meter range and for mountainous areas in the 2-3 meter range, consistent with theoretical expectations. We also discuss key factors that presently limit the system performance. RP MADSEN, SN (reprint author), CALTECH,JET PROP LAB,TUD,DANISH CTR REMOTE SENSING,4800 OAK GROVE DR,PASADENA,CA 91109, USA. RI Namikawa, Laercio/C-5559-2013 OI Namikawa, Laercio/0000-0001-7847-1804 NR 14 TC 42 Z9 45 U1 0 U2 5 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1995 VL 33 IS 2 BP 383 EP 391 DI 10.1109/36.377938 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA QN940 UT WOS:A1995QN94000016 ER PT J AU KWOK, R ROTHROCK, DA STERN, HL CUNNINGHAM, GF AF KWOK, R ROTHROCK, DA STERN, HL CUNNINGHAM, GF TI DETERMINATION OF THE AGE DISTRIBUTION OF SEA-ICE FROM LAGRANGIAN OBSERVATIONS OF ICE MOTION SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article AB A procedure for monitoring the local age distribution of the Arctic sea ice cover is presented. The age distribution specifies the area covered by ice in different age classes. In our approach, a regular array of grid points is defined initially on the first image of a long time series, and an ice tracker finds the positions of those points in all subsequent images of the series. These Lagrangian points mark the corners of a set of cells that move and deform with the ice cover. The area of each cell changes with each new image or time step. A positive change indicates that ice in a new age class was formed in the cell. A negative change is assumed to have ridged the youngest ice in the cell, reducing its area. The ice in each cell ages as it progresses through the time series. The area of multiyear ice in each cell is computed using an ice classification algorithm. Any area that is not accounted for by the young ice or multiyear ice is assigned to a category of older first-year ice. We thus have a fine age resolution in the young end of the age distribution, and coarse resolution for older ice. The age distribution of the young ice can be converted to a thickness distribution using a simple empirical relation between accumulated freezing-degree days and ice thickness, or using a more complicated thermodynamic model. We describe a general scheme for implementing this procedure for the Arctic Ocean from fall freeze-up until the onset of melt in the spring. The concept is illustrated with a time series of five ERS-1 SAR images spanning a period of 12 days. Such a scheme could be implemented with RADARSAT SAR imagery to provide basin-wide ice age and thickness information. C1 UNIV WASHINGTON,COLL OCEAN & FISHERY SCI,APPL PHYS LAB,SEATTLE,WA 98195. CALTECH,JET PROP LAB,RADAR SCI & ENGN SECT,SAR SYST DEV & PROC GRP,PASADENA,CA 91109. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 12 TC 39 Z9 39 U1 0 U2 3 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1995 VL 33 IS 2 BP 392 EP 400 DI 10.1109/36.377939 PG 9 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA QN940 UT WOS:A1995QN94000017 ER PT J AU MYNENI, RB HALL, FG SELLERS, PJ MARSHAK, AL AF MYNENI, RB HALL, FG SELLERS, PJ MARSHAK, AL TI THE INTERPRETATION OF SPECTRAL VEGETATION INDEXES SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID LEAF-AREA INDEX; SOIL; REFLECTANCE; MODEL; RED AB Empirical studies report several plausible correlations between transforms of spectral reflectance, called vegetation indexes, and parameters descriptive of vegetation leaf area, biomass and physiological functioning. However, most indexes can be generalized to show a derivative of surface reflectance with respect to wavelength. This derivative is a function of the optical properties of leaves and soil particles. In the case of optically dense vegetation, the spectral derivative, and thus the indexes, can be rigorously shown to be indicative of the abundance and activity of the absorbers in the leaves. Therefore, the widely used broad-band red/near-infrared vegetation indexes are a measure of chlorophyll abundance and energy absorption. C1 NASA,GODDARD SPACE FLIGHT CTR,SSAI,CLIMATE & RADIAT BRANCH,GREENBELT,MD 20771. RP MYNENI, RB (reprint author), UNIV MARYLAND,NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,MAIL CODE 923,GREENBELT,MD 20771, USA. RI Marshak, Alexander/D-5671-2012; Myneni, Ranga/F-5129-2012 NR 30 TC 549 Z9 576 U1 14 U2 105 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1995 VL 33 IS 2 BP 481 EP 486 DI 10.1109/36.377948 PG 6 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA QN940 UT WOS:A1995QN94000026 ER PT J AU BREON, FM TANRE, D LECOMTE, P HERMAN, M AF BREON, FM TANRE, D LECOMTE, P HERMAN, M TI POLARIZED REFLECTANCE OF BARE SOILS AND VEGETATION - MEASUREMENTS AND MODELS SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Article ID LIGHT; CANOPY; ATMOSPHERE; DIFFUSE AB This paper presents a large set of spectral and directional, signatures of the polarized reflectance acquired over various surfaces. Two analytical physically-based models were developed, one for bare soils and the other for simple vegetation cover. They consider that the polarized reflectance is generated by single specular reflection over isotropically distributed facets or leaves. The models accurately reproduce the order of magnitude and the directional signature of the reflectance for view angles of up to approximate to 55 degrees. It confirms that specular reflection is the main process that generates polarization over natural surfaces. Polarized light generated by other processes, and that are not accounted for by the models, can be observed however in the backscattering direction where single specular reflection does not yield polarization. Although spectral variations in the polarized reflectance are observed, they are explained by atmospheric effects on the direct solar beam. The atmospheric correction yields a surface polarized reflectance which is larger than the model estimate, but is still on the same order of magnitude. For the simple canopies studied, our results suggest that, except for particular events such as the ''heading'' of a canopy, vegetation will generate little variability in the polarized reflectance making this information unsuitable for monitoring of the canopies. On the other hand, since the models accurately predict the polarized reflectance from the surface, they can be used to correct airborne or spaceborne polarized reflectance measurements when the inversion of aerosol parameters is attempted. C1 UNIV SCI & TECH LILLE FLANDRES ARTOIS,LOA,CNRS,URA 713,F-59655 VILLENEUVE DASCQ,FRANCE. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP BREON, FM (reprint author), CEA,LMCE,LORME MERISIERS,F-91191 GIF SUR YVETTE,FRANCE. RI Breon, Francois-Marie/M-4639-2016 OI Breon, Francois-Marie/0000-0003-2128-739X NR 44 TC 73 Z9 88 U1 1 U2 18 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1995 VL 33 IS 2 BP 487 EP 499 DI 10.1109/36.377949 PG 13 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA QN940 UT WOS:A1995QN94000027 ER PT J AU IMHOFF, ML AF IMHOFF, ML TI RADAR BACKSCATTER AND BIOMASS SATURATION - RAMIFICATIONS FOR GLOBAL BIOMASS INVENTORY SO IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING LA English DT Note ID FOREST BIOMASS; VEGETATION; SAR AB Two SAR and biomass data sets of forests with different canopy architectures were examined for commonalties regarding backscatter/biomass saturation. The SAR data were collected using the NASA/JPL AIRSAR at incidence angles between 400 and 50 degrees for tropical broadleaf evergreen forests in Hawaii and coniferous forests in North America and Europe. Radar signal saturation limits with respect to biomass for both forest types were determined to be approximate to 100 tons/ha for P-band (0.44 GHz), approximate to 40 tons/ha for L-band (1.25 GHz), and approximate to 20 tons/ha for C-band (5.3 GHz). The effect of the saturation limits on making global biomass inventories with SAR sensors was assessed by comparing the biomass saturation limits to a global vegetation type and biomass data base. C-band can be used to measure biomass in biomes covering 25% of the world's total ice-free vegetated surface area accounting for 4% of Earth's store of terrestrial phytomass. L- and P-band can be used to measure biomass in biomes covering 37% and 62% of the total vegetated surface area accounting for 8% and 19% of Earth's pool of terrestrial phytomass respectively. Biomes occupying approximately 38% of Earth's vegetated surface area containing 81% of the estimated total terrestrial phytomass have biomass densities above the saturation limit of current SAR systems (>100 tons/ha for P-band). Since P-band radar systems cannot Currently operate effectively from orbit, the use of SAR sensors for biomass surveys may be limited even further to the L-band threshold. Emphasis should be shifted toward using SAR to characterize forest regeneration and development up to the saturation limits shown here rather than attempting to measure biomass directly in heavy forests. The development of new and innovative technologies for measuring biomass in high density vegetation is encouraged. RP IMHOFF, ML (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 923,GREENBELT,MD 20771, USA. NR 22 TC 225 Z9 243 U1 4 U2 19 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0196-2892 J9 IEEE T GEOSCI REMOTE JI IEEE Trans. Geosci. Remote Sensing PD MAR PY 1995 VL 33 IS 2 BP 511 EP 518 DI 10.1109/36.377953 PG 8 WC Geochemistry & Geophysics; Engineering, Electrical & Electronic; Remote Sensing; Imaging Science & Photographic Technology SC Geochemistry & Geophysics; Engineering; Remote Sensing; Imaging Science & Photographic Technology GA QN940 UT WOS:A1995QN94000031 ER PT J AU FARRELL, WM THOMPSON, RF LEPPING, RP BYRNES, JB AF FARRELL, WM THOMPSON, RF LEPPING, RP BYRNES, JB TI A METHOD OF CALIBRATING MAGNETOMETERS ON A SPINNING SPACECRAFT SO IEEE TRANSACTIONS ON MAGNETICS LA English DT Article AB This paper describes a procedure for quantifying and compensating for angular offsets and slow-varying drifts associated with a flux-gate magnetometer onboard a spinning spacecraft. Such magnetometers have been flown on numerous spacecraft such as IMP-8, DE-1, and ISTP/GEOTAIL, and similar instruments are currently proposed to fly on the ISTP/WIND spacecraft. Consequently, slight geometric misalignment of the sensor from their chosen axes will create errors in the measured signal. These misalignments can be quantified using perturbation theory and compensated in the data analysis process. The technique is applicable to magnetometers on spinning spacecraft. Also, over long time periods, the magnetometer will develop slight drifts in the electronic components, and these too can be quantified in the data analysis process. We shall discuss a technique that quantifies and compensates for such perturbations from the measurements. The technique has been successfully applied for the last sixteen years to IMP-8 magnetometer data and more currently to the GEOTAIL magnetometer data, and can be applied in a general way to measurements from any magnetometer onboard a spinning spacecraft. Further improvements in the technique will also be discussed. RP FARRELL, WM (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Farrell, William/I-4865-2013 NR 4 TC 6 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 0018-9464 J9 IEEE T MAGN JI IEEE Trans. Magn. PD MAR PY 1995 VL 31 IS 2 BP 966 EP 972 DI 10.1109/20.364770 PG 7 WC Engineering, Electrical & Electronic; Physics, Applied SC Engineering; Physics GA QH843 UT WOS:A1995QH84300008 ER PT J AU WELLER, TM KATEHI, LPB REBEIZ, GM AF WELLER, TM KATEHI, LPB REBEIZ, GM TI HIGH-PERFORMANCE MICROSHIELD LINE COMPONENTS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID COPLANAR WAVE-GUIDES; TRANSMISSION-LINES; DISCONTINUITIES; CIRCUITS AB Several millimeter-wave passive components have been fabricated using the microshield transmission line geometry, and their performance is presented herein, Microshield is a quasi-planar, half-shielded design which uses a thin dielectric membrane (1.5 mu m) to support the conducting lines, This approach provides a nearly homogeneous, air-filled environment and thus allows extremely broad-band TEM operation, This paper examines the conductor loss and effective dielectric constant of microshield lines and presents results on transitions to conventional coplanar waveguide, right-angle bends, different stub configurations, and lowpass and bandpass filters, Experimental data is provided along with numerical results derived from an integral equation method, The microshield line is shown to be very suitable for high performance millimeter- and submillimeter-wave applications. RP UNIV MICHIGAN, NASA, CTR SPACE TERAHERTZ TECHNOL, ANN ARBOR, MI 48109 USA. NR 29 TC 79 Z9 80 U1 2 U2 6 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI PISCATAWAY PA 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA SN 0018-9480 EI 1557-9670 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAR PY 1995 VL 43 IS 3 BP 534 EP 543 DI 10.1109/22.372098 PG 10 WC Engineering, Electrical & Electronic SC Engineering GA QM887 UT WOS:A1995QM88700010 ER PT J AU SUBRAMANYAM, G KAPOOR, VJ BHASIN, KB AF SUBRAMANYAM, G KAPOOR, VJ BHASIN, KB TI A HYBRID PHASE-SHIFTER CIRCUIT BASED ON TLCABACUO SUPERCONDUCTING THIN-FILMS SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Article ID FABRICATION AB A superconductor-semiconductor hybrid reflection-type phase shifter circuit has been designed, fabricated, and characterized for 180 degrees phase bit with center frequency of 4 GHz and bandwidth of 0.5 GHz for operation at 77 K, All of the passive components of the phase shifter circuit such as input/output feed lines, 3 dB Lange coupler, impedence matching networks, and transmission lines consisted of thallium based superconducting TlCaBaCuO thin films of 4000 Angstrom thickness on lanthanum aluminate substrate, Metal-Schottky field-effect transistors (MESFET's) on GaAs semiconductor were used as active devices for switching action (on-state and off-state) in the phase shifter circuit, The phase shift and insertion losses were investigated as a function of frequency from 3.6 to 4.6 GHz at 77 K, The circuit exhibited a fairly flat response of 180 degrees phase shift with a maximum deviation of less than 2 degrees and a maximum insertion loss of 2 dB for on-state and 2.2 dB for off-state conditions over 0.5 GHz bandwidth at 4 GHz, The insertion losses were also fairly flat within the bandwidth, The insertion losses were constant between 50 and 80 K, giving the circuit a large range of operation at or below 77 K, The performance of this circuit as compared to a gold microstrip-semiconductor circuit designed identically was superior by a factor of 1.5, and may be due to lower conductor losses and lower surface resistance in the superconducting microstrips. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. UNIV CINCINNATI,DEPT ELECT & COMP ENGN,MICROWAVE ELECTR LAB,CINCINNATI,OH 45221. NR 19 TC 5 Z9 5 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAR PY 1995 VL 43 IS 3 BP 566 EP 572 DI 10.1109/22.372102 PG 7 WC Engineering, Electrical & Electronic SC Engineering GA QM887 UT WOS:A1995QM88700014 ER PT J AU RAISANEN, AV TOLMUNEN, TJ NATZIC, M FRERKING, MA BROWN, E GRONQVIST, H NILSEN, SM AF RAISANEN, AV TOLMUNEN, TJ NATZIC, M FRERKING, MA BROWN, E GRONQVIST, H NILSEN, SM TI A SINGLE BARRIER VARACTOR QUINTUPLER AT 170 GHZ SO IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES LA English DT Note ID SUBMILLIMETER WAVELENGTHS; WAVE MULTIPLIERS; MILLIMETER-WAVE; DIODES AB InGaAs/InAlAs single-barrier varactor (SBV) diodes are tested as frequency quintuplers. The diodes were tested in a crossed-waveguide structure and provided output frequencies between 148 and 187 GHz. The highest observed flange-to-flange efficiency was 0.78% at an output frequency of 172 GHz. This is nearly four times greater than the best quintupler efficiency obtained for previous SBV varactors made from the GaAs/AlGaAs materials system. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. MIT,LINCOLN LAB,LEXINGTON,MA 02173. CHALMERS UNIV TECHNOL,DEPT APPL ELECTRON PHYS,S-41296 GOTHENBURG,SWEDEN. RP RAISANEN, AV (reprint author), HELSINKI UNIV TECHNOL,RADIO LAB,SF-02150 ESPOO,FINLAND. RI Raisanen, Antti/G-2405-2013 NR 8 TC 18 Z9 18 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9480 J9 IEEE T MICROW THEORY JI IEEE Trans. Microw. Theory Tech. PD MAR PY 1995 VL 43 IS 3 BP 685 EP 688 DI 10.1109/22.372117 PG 4 WC Engineering, Electrical & Electronic SC Engineering GA QM887 UT WOS:A1995QM88700029 ER PT J AU SALEE, D BARAM, Y AF SALEE, D BARAM, Y TI HIGH-CAPACITY HEBBIAN STORAGE BY SPARSE SAMPLING SO IEEE TRANSACTIONS ON NEURAL NETWORKS LA English DT Article ID NEURAL NETWORKS; ASSOCIATIVE MEMORIES AB The capacity of networks of ternary neurons, storing, by the so-called Hebbian rule, sparse vectors over {-1, 0, 1}(N), is shown to be at least of the order of N-2/K log N, where K = Omega (log N) is the number of nonzero elements in each vector. The error correction capability of such networks is also analyzed. These results generalize previously known capacity bounds for binary networks storing vectors of equally probable {+/-1} bits and yield considerably higher capacities for small values of K. C1 TECHNION ISRAEL INST TECHNOL,DEPT COMP SCI,IL-32000 HAIFA,ISRAEL. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP SALEE, D (reprint author), DEPT DEF,ISRAEL DEF FORCES,JERUSALEM,ISRAEL. NR 13 TC 1 Z9 1 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 1045-9227 J9 IEEE T NEURAL NETWOR JI IEEE Trans. Neural Netw. PD MAR PY 1995 VL 6 IS 2 BP 349 EP 356 DI 10.1109/72.363470 PG 8 WC Computer Science, Artificial Intelligence; Computer Science, Hardware & Architecture; Computer Science, Theory & Methods; Engineering, Electrical & Electronic SC Computer Science; Engineering GA QJ922 UT WOS:A1995QJ92200005 PM 18263317 ER PT J AU NICOL, DM PALUMBO, DL AF NICOL, DM PALUMBO, DL TI RELIABILITY-ANALYSIS OF COMPLEX-MODELS USING SURE BOUNDS SO IEEE TRANSACTIONS ON RELIABILITY LA English DT Article DE MARKOV ANALYSIS; STATE-SPACE EXPLORATION; USER-ASSISTED PRUNING; PARALLEL PROCESSING; MONTE CARLO ESTIMATION ID SIMULATION; SYSTEMS AB As computer and communication systems become more complex it becomes increasingly more difficult to analyze their hardware reliability, because simple models can fail to adequately-capture subtle but important features. This paper describes several ways we have addressed this problem for analyses based upon White's SURE theorem. We show: how reliability analysis based on SURE mathematics can attack very large problems by accepting recomputation in order to reduce memory usage how such analysis can be parallelized both on multiprocessors and on networks of ordinary workstations, and obtain excellent performance gains by doing so how the SURE theorem supports efficient Monte Carlo based estimation of reliability the advantages of the method. Empirical studies of large models solved using these methods show that they are effective in reducing the solution-time of large complex problems. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23665. RP NICOL, DM (reprint author), COLL WILLIAM & MARY,DEPT COMP SCI,POB 8795,WILLIAMSBURG,VA 23187, USA. NR 12 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 0018-9529 J9 IEEE T RELIAB JI IEEE Trans. Reliab. PD MAR PY 1995 VL 44 IS 1 BP 46 EP 53 DI 10.1109/24.376521 PG 8 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA QQ330 UT WOS:A1995QQ33000013 ER PT J AU DOYLE, SA DUGAN, JB PATTERSONHINE, FA AF DOYLE, SA DUGAN, JB PATTERSONHINE, FA TI A COMBINATORIAL APPROACH TO MODELING IMPERFECT COVERAGE SO IEEE TRANSACTIONS ON RELIABILITY LA English DT Article DE FAULT TREE; DIGRAPH MODEL; IMPERFECT COVERAGE; FAULT TOLERANT SYSTEMS ID FAULT-TOLERANT SYSTEMS; RELIABILITY-ANALYSIS AB A new algorithm combines a coverage model with a combinatorial model to compute system unreliability. Its advantage is that for a class of systems, it is simpler than current algorithms. The method applies to combinatorial models which can generate cutsets for the system. This set of cutsets is augmented with cutsets representing the uncovered failures of the system, The resulting set is manipulated by combining standard multi-state and sum-of-disjoint products solution techniques. It is possible to compute the exact unreliability of the system using this algorithm. If the size of the system and the time required for the analysis become prohibitive, however, the solution can be truncated and bounds on the system unreliability computed. Our algorithm is important because it adapts standard combinatorial solution techniques to a problem that was previously thought to require a Markov solution. The ability to model a fault-tolerant computer system completely within a combinatorial model allows results to be calculated more quickly and accurately, and thus to impact system design. This new technology is easily integrated into existing design/analysis methodologies. Coverage provides a more accurate picture of system behavior, and gives us more faith in our reliability estimates. C1 UNIV VIRGINIA,DEPT ELECT ENGN,CHARLOTTESVILLE,VA 22903. RES TRIANGLE INST,RES TRIANGLE PK,NC 27709. NASA,AMES RES CTR,DIV INFORMAT SCI,DEPENDABLE MULTIPROC GRP,MOFFETT FIELD,CA 94035. RP DOYLE, SA (reprint author), DUKE UNIV,DEPT COMP SCI,CBOX 90129,DURHAM,NC 27708, USA. NR 22 TC 39 Z9 43 U1 0 U2 0 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0018-9529 J9 IEEE T RELIAB JI IEEE Trans. Reliab. PD MAR PY 1995 VL 44 IS 1 BP 87 EP 94 DI 10.1109/24.376525 PG 8 WC Computer Science, Hardware & Architecture; Computer Science, Software Engineering; Engineering, Electrical & Electronic SC Computer Science; Engineering GA QQ330 UT WOS:A1995QQ33000017 ER PT J AU RORVIG, ME AF RORVIG, ME TI PATTERN-RECOGNITION ENGINEERING - NADLER,M, SMITH,EP SO INFORMATION PROCESSING & MANAGEMENT LA English DT Book Review RP RORVIG, ME (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,INFORMAT SYST DIRECTORATE,HOUSTON,TX 77058, USA. NR 6 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0306-4573 J9 INFORM PROCESS MANAG JI Inf. Process. Manage. PD MAR-APR PY 1995 VL 31 IS 2 BP 257 EP 258 DI 10.1016/0306-4573(95)80046-V PG 2 WC Computer Science, Information Systems; Information Science & Library Science SC Computer Science; Information Science & Library Science GA QL320 UT WOS:A1995QL32000014 ER PT J AU ENGELBERG, M MENNINGER, MD AF ENGELBERG, M MENNINGER, MD TI VIRTUAL WORLDS AND MULTIMEDIA - THALMANN,NM, THALMANN,D SO INFORMATION PROCESSING & MANAGEMENT LA English DT Book Review RP ENGELBERG, M (reprint author), NASA,LINCOM CORP,HOUSTON,TX 77058, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0306-4573 J9 INFORM PROCESS MANAG JI Inf. Process. Manage. PD MAR-APR PY 1995 VL 31 IS 2 BP 258 EP 259 DI 10.1016/0306-4573(95)80047-W PG 2 WC Computer Science, Information Systems; Information Science & Library Science SC Computer Science; Information Science & Library Science GA QL320 UT WOS:A1995QL32000015 ER PT J AU WHITMORE, M MOUNT, FE AF WHITMORE, M MOUNT, FE TI MICROGRAVITY MAINTENANCE WORKSTATION DEVELOPMENT SO INTERNATIONAL JOURNAL OF INDUSTRIAL ERGONOMICS LA English DT Article DE WORKSTATION DESIGN; MAINTENANCE; ERGONOMIC EVALUATIONS; ANTHROPOMETRIC EVALUATIONS; GLOVEBOX DESIGN AB Space Station maintenance workstation will be used to support equipment servicing and repair operations. The maintenance workstation provides different work area configurations, giving open workbench or a contained area. In the conceptual design evaluated, up to five operators can work at the workstation simultaneously. A series of maintenance workstation evaluations have been conducted at NASA Johnson Space Center to determine the critical design issues relating to human-machine interfaces. A primary goal of this work was to verify whether the proposed design accommodated a wide range of users and maintenance task requirements under microgravity conditions. The tests were conducted onboard NASA's KC-135 microgravity aircraft. Three crew and six non-crew subjects participated in the studies. Tasks performed during the evaluations consisted of reach sweeps, force/torque task, soldering, handling large objects and lens replacement. Each session was videotaped for post-flight observations. In addition, subjects were asked to fill out a questionnaire following the flight. These microgravity evaluations were complemented by the computer modeling of different statures to investigate the viewing, reach, and head clearances. Results indicate that the size and location of the glove ports, and the enclosed work volume are the critical design concerns. The approach, findings and implications of the study are discussed. C1 LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. RP WHITMORE, M (reprint author), NASA,JOHNSON SPACE CTR,HUMAN FACTORS & ERGON LAB,2400 NASA RD 1,HOUSTON,TX 77058, USA. NR 2 TC 0 Z9 0 U1 1 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0169-8141 J9 INT J IND ERGONOM JI Int. J. Ind. Ergon. PD MAR PY 1995 VL 15 IS 3 BP 189 EP 197 DI 10.1016/0169-8141(94)00034-Z PG 9 WC Engineering, Industrial; Ergonomics SC Engineering GA QU303 UT WOS:A1995QU30300004 ER PT J AU BRINSON, LC GATES, TS AF BRINSON, LC GATES, TS TI EFFECTS OF PHYSICAL AGING ON LONG-TERM CREEP OF POLYMERS AND POLYMER MATRIX COMPOSITES SO INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES LA English DT Article AB For many polymeric materials in use below the glass transition temperature, the long term viscoelastic behavior is greatly affected by physical aging. To use polymer matrix composites as critical structural components in existing and novel technological applications, this long term behavior of the material system must be understood. Towards that end, this study applied the concepts governing the mechanics of physical aging in a consistent manner to the study of laminated composite systems. Even in fiber dominated lay-ups, the effects of physical aging are found to be important in the long term behavior of the composite. This paper first lays out, in a self-consistent manner, the basic concepts describing physical aging of polymers. Several aspects of physical aging which have not been previously documented are also explored in this study, namely the effects of aging into effective equilibrium and a relationship to the time-temperature shift factor, The physical aging theory is then extended to develop the long term compliance/modulus of a single lamina with varying fiber orientation. The latter is then built into classical lamination theory to predict long time response of general laminated composites. Comparison to experimental data is excellent. In the investigation of fiber oriented lamina and laminates, it is illustrated that the long term response can be counter-intuitive, stressing the need for consistent modeling efforts to make long term predictions of laminates to be used in structural situations. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23681. RP BRINSON, LC (reprint author), NORTHWESTERN UNIV,DEPT MECH ENGN,EVANSTON,IL 60202, USA. RI Brinson, L. Catherine/B-6678-2009; Brinson, L Catherine/B-1315-2013 OI Brinson, L Catherine/0000-0003-2551-1563 NR 17 TC 92 Z9 92 U1 2 U2 23 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0020-7683 J9 INT J SOLIDS STRUCT JI Int. J. Solids Struct. PD MAR-APR PY 1995 VL 32 IS 6-7 BP 827 EP 846 DI 10.1016/0020-7683(94)00163-Q PG 20 WC Mechanics SC Mechanics GA QH498 UT WOS:A1995QH49800008 ER PT J AU TRINH, EH OHSAKA, K AF TRINH, EH OHSAKA, K TI MEASUREMENT OF DENSITY, SOUND-VELOCITY, SURFACE-TENSION, AND VISCOSITY OF FREELY SUSPENDED SUPERCOOLED LIQUIDS SO INTERNATIONAL JOURNAL OF THERMOPHYSICS LA English DT Article; Proceedings Paper CT 12th Symposium on Thermophysical Properties CY JUN 19-24, 1994 CL UNIV COLORADO, BOULDER, CO SP NIST, Chem Sci & Technol Lab, Thermophys Div, Amer Soc Mech Engineers, Heat Transfer Div, Comm Thermophys Properties HO UNIV COLORADO DE DENSITY; LEVITATION TECHNIQUE; SUPERCOOLING; SURFACE TENSION; SOUND VELOCITY; VISCOSITY ID ACOUSTIC LEVITATION; DROPS; WATER; OSCILLATION AB Noncontact methods have been implemented in conjunction with levitation techniques to carry out the measurement of the macroscopic properties of liquids significantly cooled below their nominal melting point. Free suspension of the sample and remote methods allow the deep excursion into the metastable liquid state and the determination of its thermophysical properties. We used this approach to investigate common substances such as water, o-terphenyl, succinonitrile, as well as higher temperature melts such as molten indium, aluminum, and other metals. Although these techniques have thus far involved ultrasonic, electromagnetic, and more recently electrostatic levitation, we restrict our attention to ultrasonic methods in this paper. The resulting magnitude of maximum thermal supercooling achieved has ranged between 10% and 15% of the absolute temperature of the melting point for the materials mentioned above. The methods for measuring the physical properties have been mostly novel approaches, and the typical accuracy achieved has not yet matched the standard equivalent techniques involving contained samples and invasive probing. They are currently being refined, however, as the levitation techniques become more widespread and as we gain a better understanding of the physics of levitated liquid samples. RP TRINH, EH (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 25 TC 37 Z9 38 U1 3 U2 21 PU PLENUM PUBL CORP PI NEW YORK PA 233 SPRING ST, NEW YORK, NY 10013 SN 0195-928X J9 INT J THERMOPHYS JI Int. J. Thermophys. PD MAR PY 1995 VL 16 IS 2 BP 545 EP 555 DI 10.1007/BF01441920 PG 11 WC Thermodynamics; Chemistry, Physical; Mechanics; Physics, Applied SC Thermodynamics; Chemistry; Mechanics; Physics GA QU937 UT WOS:A1995QU93700026 ER PT J AU MCLACHLAN, BG BELL, JH PARK, H KENNELLY, RA SCHREINER, JA SMITH, SC STRONG, JM GALLERY, J GOUTERMAN, M AF MCLACHLAN, BG BELL, JH PARK, H KENNELLY, RA SCHREINER, JA SMITH, SC STRONG, JM GALLERY, J GOUTERMAN, M TI PRESSURE-SENSITIVE PAINT MEASUREMENTS ON A SUPERSONIC HIGH-SWEEP OBLIQUE WING MODEL SO JOURNAL OF AIRCRAFT LA English DT Article AB The pressure-sensitive paint method was used in the test of a high-sweep oblique wing model, conducted in the NASA Ames 9- by 7-ft Supersonic Wind Tunnel. Surface pressure data was acquired from both the luminescent paint and conventional pressure taps at Mach numbers between M = 1.6 and 2.0. In addition, schlieren photographs of the outer flow were used to determine the location of shock waves impinging on the model. The results show that the luminescent pressure-sensitive paint can capture both global and fine features of the static surface pressure field. Comparison with conventional pressure tap data shows good agreement between the two techniques, and that the luminescent paint data can be used to make quantitative measurements of the pressure changes over the model surface. The experiment also demonstrates the practical considerations and limitations that arise in the application of this technique under supersonic flow conditions in large-scale facilities, as well as the directions in which future research is necessary in order to make this technique a more practical wind-tunnel testing tool. RP MCLACHLAN, BG (reprint author), NASA,AMES RES CTR,DIV AERODYNAM,M-S 227-2,MOFFETT FIELD,CA 94035, USA. NR 0 TC 10 Z9 10 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAR-APR PY 1995 VL 32 IS 2 BP 217 EP 227 DI 10.2514/3.56921 PG 11 WC Engineering, Aerospace SC Engineering GA QR089 UT WOS:A1995QR08900001 ER PT J AU EKATERINARIS, JA SCHIFF, LB AF EKATERINARIS, JA SCHIFF, LB TI NAVIER-STOKES SOLUTION FOR AN OSCILLATING DOUBLE-DELTA WING SO JOURNAL OF AIRCRAFT LA English DT Article AB Steady-state and unsteady Navier-Stokes solutions of the vortical flow over a double-delta wing configuration, consisting of a sharp leading-edge 76-deg sweep strake and a 40-deg sweep wing section are presented. The governing equations are solved numerically with an upwind-biased, implicit, iterative, and factorized numerical scheme. At fixed angles of incidence, the steady-state flow and the leeward-side vortex system resulting from the strake and wing vortices are investigated for subsonic, high Reynolds number flows. The unsteady flowfield development resulting from the large amplitude oscillatory motion of the wing around a mean angle of attack of alpha = 22.4 deg, with an amplitude of 6.8 deg, is also investigated. Lag in the appearance of vortex breakdown caused by the pitch-up motion is found in accordance with the experiment. The computed unsteady solution is compared with available unsteady flow measurements at several phase angles during the oscillation cycle. RP EKATERINARIS, JA (reprint author), NASA,AMES RES CTR,USN,POSTGRAD SCH,DEPT AERONAT & ASTRONAUT,JOINT INST AERONAUT,MOFFETT FIELD,CA 94035, USA. NR 0 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 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAR-APR PY 1995 VL 32 IS 2 BP 228 EP 234 DI 10.2514/3.46708 PG 7 WC Engineering, Aerospace SC Engineering GA QR089 UT WOS:A1995QR08900002 ER PT J AU MORELLI, EA AF MORELLI, EA TI GLOBAL NONLINEAR AERODYNAMIC MODELING USING MULTIVARIATE ORTHOGONAL FUNCTIONS SO JOURNAL OF AIRCRAFT LA English DT Article AB A technique was developed for global modeling of nonlinear aerodynamic coefficients using multivariate orthogonal functions generated from the data. The orthogonality of the modeling functions allowed straightforward determination of an adequate model structure and the associated parameter values. A minimum predicted squared-error criterion was used to determine which orthogonal functions should be retained in the model. Each retained orthogonal function was then decomposed into an expansion of ordinary polynomials in the independent variables so that the final model could be interpreted as selectively retained terms from a multivariable power series expansion. The approach was demonstrated on the Z body axis aerodynamic force coefficient C(Z) for the F-18 High Angle of Attack Research Vehicle. The data came from a tabular wind-tunnel data base and covered the entire subsonic flight envelope. For a realistic prediction case, the analytical model predicted C(Z) within 5% of the wind-tunnel values. The modeling technique developed in this article was shown to be capable of generating a compact, global analytical representation of nonlinear aerodynamics. The resultant polynomial model demonstrated good predictive capability, global validity, analytical differentiability, and improved insight into the character of the nonlinear aerodynamics. RP MORELLI, EA (reprint author), NASA,LANGLEY RES CTR,M-S 489,HAMPTON,VA 23665, USA. NR 0 TC 24 Z9 28 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-APR PY 1995 VL 32 IS 2 BP 270 EP 277 DI 10.2514/3.46712 PG 8 WC Engineering, Aerospace SC Engineering GA QR089 UT WOS:A1995QR08900006 ER PT J AU ROSSOW, VJ SACCO, JN ASKINS, PA BISBEE, LS SMITH, SM AF ROSSOW, VJ SACCO, JN ASKINS, PA BISBEE, LS SMITH, SM TI WIND-TUNNEL MEASUREMENTS OF HAZARD POSED BY LIFE-GENERATED WAKES SO JOURNAL OF AIRCRAFT LA English DT Article AB The results obtained during a wake-vortex test conducted in the NASA Ames Research Center 80- by 120-ft Wind Tunnel are described. The wind-tunnel test is part of an FAA and NASA program to study the characteristics of lift-generated vortices in order to safely increase airport capacity for subsonic transports. Data was first obtained to confirm that measurements in the 80- by 120-ft Wind Tunnel are in agreement with those taken in the 40- by 80-ft Wind Tunnel during the test program of the 1970s. Measurements are then presented on the maximum rolling moment induced on following models of various sizes when they encounter the vortex wakes shed by several configurations of a subsonic transport. Finally, measurements are presented of the lift and rolling moment induced on various following models, and of the downwash, as a function of spanwise distance in the wake. The wing spans of the followers vary from 0.085 to 1.022 times the span of the wake-generating model. RP ROSSOW, VJ (reprint author), NASA,AMES RES CTR,MOFFETT FIELD,CA 94035, USA. NR 0 TC 10 Z9 10 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAR-APR PY 1995 VL 32 IS 2 BP 278 EP 284 DI 10.2514/3.46713 PG 7 WC Engineering, Aerospace SC Engineering GA QR089 UT WOS:A1995QR08900007 ER PT J AU BLOSSER, ML SCHWOERKE, S BRUNSON, D HAGSETH, OP AF BLOSSER, ML SCHWOERKE, S BRUNSON, D HAGSETH, OP TI WING LEADING-EDGE DESIGN CONCEPTS FOR AIRBREATHING HYPERSONIC WAVERIDERS SO JOURNAL OF AIRCRAFT LA English DT Article AB Wing leading-edge structural concepts are considered in this article for a specific Mach 5 waverider cruise vehicle. Design tradeoffs, such as making the leading edges sharp enough for acceptable aerodynamic and propulsion efficiency, yet blunt enough for acceptable aerodynamic heating, are discussed. Aerodynamic heating distributions are calculated for two locations on the leading edge of the vehicle. Several structural concepts are discussed and a particular concept is studied. Temperature and thermal stress distributions are calculated for a simple wing leading-edge concept consisting of an uninsulated hot structure. Techniques for reducing thermal stresses are discussed. RP BLOSSER, ML (reprint author), NASA,LANGLEY RES CTR,THERMAL STRUCT BRANCH,MS 396,HAMPTON,VA 23681, USA. NR 0 TC 3 Z9 3 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0021-8669 J9 J AIRCRAFT JI J. Aircr. PD MAR-APR PY 1995 VL 32 IS 2 BP 307 EP 322 DI 10.2514/3.46717 PG 16 WC Engineering, Aerospace SC Engineering GA QR089 UT WOS:A1995QR08900011 ER PT J AU RANEY, DL MCMINN, JD POTOTZKY, AS AF RANEY, DL MCMINN, JD POTOTZKY, AS TI IMPACT OF AEROELASTIC-PROPULSIVE INTERACTIONS ON FLIGHT DYNAMICS OF A HYPERSONIC VEHICLE SO JOURNAL OF AIRCRAFT LA English DT Article AB Many air-breathing hypersonic vehicle design concepts utilize the lower surface of an elongated fuselage forebody to provide aerodynamic compression for a supersonic combustion ramjet module, or a scramjet. This highly integrated design approach creates the potential for an unprecedented form of aeroelastic-propulsive interaction in which deflections of the vehicle fuselage give rise to propulsive force and moment variations that may impact the vehicle's flight dynamic characteristics. This investigation examines the potential for such interactions using a math model that describes the longitudinal flight dynamics, propulsion system, and first seven elastic modes of a hypersonic vehicle concept. Estimates of the propulsion system sensitivity to angle-of-attack variations and modal fuselage deflections are presented and compared with predictions based on an earlier reference. The combined aeroelastic-propulsive model is used to illustrate a variation in the vehicle's longitudinal flight dynamics with the propulsion system sensitivities. Numerical values for the completed model at flight conditions of Mach 6 and Mach 10 are presented. RP RANEY, DL (reprint author), NASA,LANGLEY RES CTR,DIV FLIGHT DYNAM & CONTROL,HAMPTON,VA 23681, USA. NR 0 TC 6 Z9 8 U1 0 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-APR PY 1995 VL 32 IS 2 BP 355 EP 362 DI 10.2514/3.46723 PG 8 WC Engineering, Aerospace SC Engineering GA QR089 UT WOS:A1995QR08900017 ER PT J AU LEERAUSCH, EM BATINA, JT AF LEERAUSCH, EM BATINA, JT TI WING FLUTTER BOUNDARY PREDICTION USING UNSTEADY EULER AERODYNAMIC METHOD SO JOURNAL OF AIRCRAFT LA English DT Article AB Modifications to an existing three-dimensional, implicit, upwind Euler/Reynolds-averaged Navier-Stokes code (CFL3D Version 2.1) for the aeroelastic analysis of wings are described. These modifications, which were previously added to CFL3D Version 1.0, include the incorporation of a deforming mesh algorithm and the addition of the structural equations of motion for their simultaneous time-integration with the governing flow equations. This article gives a brief description of these modifications and presents unsteady calculations that check the modifications to the code. Euler flutter results for an isolated 45-deg swept-back wing are compared with experimental data for seven freestream Mach numbers that define the flutter boundary over a range of Mach number from 0.499 to 1.14. These comparisons show good agreement in flutter characteristics for free-stream Mach numbers below unity. For freestream Mach numbers above unity, the computed aeroelastic results predict a premature rise in the flutter boundary as compared with the experimental boundary. Steady and unsteady contours of surface Mach number and pressure are included to illustrate the basic flow characteristics of the time-marching flutter calculations and to aid in identifying possible causes for the premature rise in the computational flutter boundary. RP LEERAUSCH, EM (reprint author), NASA,LANGLEY RES CTR,DIV STRUCT DYNAM,AEROELAST ANAL & OPTIMIZAT BRANCH,HAMPTON,VA 23681, USA. NR 0 TC 39 Z9 41 U1 0 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-APR PY 1995 VL 32 IS 2 BP 416 EP 422 DI 10.2514/3.46732 PG 7 WC Engineering, Aerospace SC Engineering GA QR089 UT WOS:A1995QR08900026 ER PT J AU SHIVAKUMAR, KN NEWMAN, JC AF SHIVAKUMAR, KN NEWMAN, JC TI STRESS-CONCENTRATION EQUATIONS FOR STRAIGHT-SHANK AND COUNTERSUNK HOLES IN PLATES SO JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME LA English DT Note AB Stress concentration equations for straight shank and countersunk holes in a large plate subjected to various lending conditions encountered in service were developed from three-dimensional finite element solutions. For straight shank holes, three types of loading: remote tension, remote bending and pin loading were considered; and for the countersunk hole only remote tension and bending loads were considered The equations are within one percent of the finite element results and are valid for isotropic materials with Poisson's ratio of 0.3. C1 NASA,LANGLEY RES CTR,HAMPTON,VA 23631. RP SHIVAKUMAR, KN (reprint author), N CAROLINA AGR & TECH STATE UNIV,DEPT MECH ENGN,GREENSBORO,NC 27405, USA. NR 7 TC 1 Z9 1 U1 0 U2 2 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 1995 VL 62 IS 1 BP 248 EP 249 DI 10.1115/1.2895916 PG 2 WC Mechanics SC Mechanics GA QR187 UT WOS:A1995QR18700041 ER PT J AU GOLDSTEIN, DS VERNIKOS, J HOLMES, C CONVERTINO, VA AF GOLDSTEIN, DS VERNIKOS, J HOLMES, C CONVERTINO, VA TI CATECHOLAMINERGIC EFFECTS OF PROLONGED HEAD-DOWN BED REST SO JOURNAL OF APPLIED PHYSIOLOGY LA English DT Article DE CATECHOLAMINES; CATECHOLS; SYMPATHETIC NERVOUS SYSTEM; ZERO GRAVITY; WEIGHTLESSNESS; NOREPINEPHRINE; EPINEPHRINE; DOPAMINE; DIHYDROXYPHENYLALANINE; DIHYDROXYPHENYGLYCOL; DIHYDROXYPHENYLACETIC ACID ID PLASMA DIHYDROXYPHENYLALANINE; URINARY-EXCRETION; NOREPINEPHRINE; RESPONSES; HUMANS; EPINEPHRINE; PRESSURE; DOPAMINE; 3,4-DIHYDROXYPHENYLGLYCOL; VOLUME AB Prolonged head-down bed rest (HDBR) provides a model for examining responses to chronic weightlessness in humans. Eight healthy volunteers underwent HDBR for 2 wk. Antecubital venous blood was sampled for plasma levels of catechols [norepinephrine (NE), epinephrine, dopamine, dihydroxyphenylalanine, dihydroxyphenylglycol, and dihydroxyphenylacetic acid] after supine rest on a control (C) day and after 4 h and 7 and 14 days of HDBR. Urine was collected after 2 h of supine rest during day C, 2 h before HDBR, and during the intervals 1-4, 4-24, 144-168 (day 7), and 312-336 h (day 14) of HDBR. All subjects had decreased plasma and blood volumes (mean 16%), atriopeptin levels (31%), and peripheral venous pressure (26%) after HDBR. NE excretion on day 14 of HDBR was decreased by 35% from that on day C, without further trends as HDBR continued, whereas plasma levels were only variably and nonsignificantly decreased. Excretion rates of dihydroxyphenylglycol and dihydroxyphenylalanine decreased slightly during HDBR; excretion rates of epinephrine, dopamine, and dihydroxyphenylacetic acid and plasma levels of catechols were unchanged. The results suggest that HDBR produces sustained inhibition of sympathoneural release, turnover, and synthesis of NE without affecting adrenomedullary secretion or renal dopamine production. Concurrent hypovolemia probably interferes with detection of sympathoinhibition by plasma levels of NE and other catechols in this setting. Sympathoinhibition, despite decreased blood volume, may help to explain orthostatic intolerance in astronauts returning from spaceflights. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. ARMSTRONG LAB,AEROSP CARDIOVASC RES LAB,BROOKS AFB,TX 78235. RP GOLDSTEIN, DS (reprint author), NINCDS,DIR,CLIN NEUROSCI BRANCH,BLDG 10,RM 6N252,9000 ROCKVILLE PIKE,BETHESDA,MD 20892, USA. NR 33 TC 49 Z9 49 U1 0 U2 0 PU AMER PHYSIOLOGICAL SOC PI BETHESDA PA 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 SN 8750-7587 J9 J APPL PHYSIOL JI J. Appl. Physiol. PD MAR PY 1995 VL 78 IS 3 BP 1023 EP 1029 PG 7 WC Physiology; Sport Sciences SC Physiology; Sport Sciences GA QP826 UT WOS:A1995QP82600036 PM 7775294 ER PT J AU FLEMING, EL CHANDRA, S JACKMAN, CH CONSIDINE, DB DOUGLASS, AR AF FLEMING, EL CHANDRA, S JACKMAN, CH CONSIDINE, DB DOUGLASS, AR TI THE MIDDLE ATMOSPHERIC RESPONSE TO SHORT AND LONG-TERM SOLAR UV VARIATIONS - ANALYSIS OF OBSERVATIONS AND 2D MODEL RESULTS SO JOURNAL OF ATMOSPHERIC AND TERRESTRIAL PHYSICS LA English DT Article ID MESOSPHERIC WATER-VAPOR; ULTRAVIOLET VARIATIONS; LOWER THERMOSPHERE; TEMPERATURE DATA; TOTAL OZONE; TERRESTRIAL MESOSPHERE; IRRADIANCE VARIATIONS; SEASONAL VARIABILITY; CYCLE RELATIONSHIP; PHOTOCHEMISTRY AB We have investigated the middle atmospheric response to the 27-day and 11-yr solar UV flux variations at low to middle latitudes using a two-dimensional photochemical model, The model reproduced most features of the observed 27-day sensitivity and phase lag of the profile ozone response in the upper stratosphere and lower mesosphere, with a maximum sensitivity of +0.51% per 1% change in 205 nm flux. The model also reproduced the observed transition to a negative phase lag above 2 mb, reflecting the increasing importance with height of the solar modulated HOx, chemistry on the ozone response above 45 km. The model revealed the general anti-correlation of ozone and solar UV at 65-75 km, and simulated strong UV responses of water vapor and HO, species in the mesosphere. Consistent with previous 1D model studies, the observed upper mesospheric positive ozone response averaged over +/-40 degrees was simulated only when the model water vapor concentrations above 75 km were significantly reduced relative to current observations. Including the observed temperature-UV response in the model to account for temperature-chemistry feedback improved the model agreement with observations in the middle mesosphere, but did not improve the overall agreement above 75 km or in the stratosphere for all time periods considered. Consistent with the short photochemical time scales in the upper stratosphere, the model computed ozone-UV sensitivity was similar for the 27-day and 11-yr variations in this region. However, unlike the 27-day variation, the model simulation of the 11-yr solar cycle revealed a positive ozone-UV response throughout the mesosphere due to the large depletion of water vapor and reduced HOx-UV sensitivity. A small negative ozone response at 65-75 km was obtained in the 11-yr simulation when temperature-chemistry feedback was included. In agreement with observations, the model computed a low to middle latitude total ozone phase lag of +3 days and a sensitivity of +0.077% per 1% change in 205 nm flux for the 27-day solar variation, and a total ozone sensitivity of +0.27% for the 11-yr solar cycle. This factor of 3 sensitivity difference is indicative of the photochemical time constant for ozone in the lower stratosphere which is comparable to the 27-day solar rotation period but is much shorter than the 11-yr solar cycle. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20785. RP FLEMING, EL (reprint author), APPL RES CORP,8201 CORP DR,LANDOVER,MD 20785, USA. RI Douglass, Anne/D-4655-2012; Jackman, Charles/D-4699-2012 NR 64 TC 93 Z9 94 U1 1 U2 2 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0021-9169 J9 J ATMOS TERR PHYS JI J. Atmos. Terr. Phys. PD MAR PY 1995 VL 57 IS 4 BP 333 EP 365 DI 10.1016/0021-9169(94)E0013-D PG 33 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QB579 UT WOS:A1995QB57900002 ER PT J AU MAHIEU, E RINSLAND, CP ZANDER, R DEMOULIN, P DELBOUILLE, L ROLAND, G AF MAHIEU, E RINSLAND, CP ZANDER, R DEMOULIN, P DELBOUILLE, L ROLAND, G TI VERTICAL COLUMN ABUNDANCES OF HCN DEDUCED FROM GROUND-BASED INFRARED SOLAR SPECTRA - LONG-TERM TREND AND VARIABILITY SO JOURNAL OF ATMOSPHERIC CHEMISTRY LA English DT Article DE HCN; INFRARED SOLAR OBSERVATIONS ID HYDROGEN-CYANIDE HCN; SPECTROSCOPIC MEASUREMENTS AB A set of high-resolution IR solar spectra recorded at the International Scientific Station of the Jungfraujoch, Switzerland, from 84/06 to 93/06, and at the National Solar Observatory McMath-Pierce solar telescope facility on Kitt Peak, Arizona, U.S.A. from 78/05 to 92/07 have been analyzed to determine the vertical column abundances of hydrogen cyanide, HCN, above the two stations. The analysis was based on least-squares curve fitting of calculated spectra to the observations encompassing the P4 and the P8 lines of HCN respectively located at 3299.5273 and 3287.2483 cm(-1). The results obtained for the two stations indicate that no significant long-term trend affects either of the two databases; however, this analysis reveals variable increases during springtime of up to a factor of 2 in the HCN total column above the Jungfraujoch and even up to 3 above Kitt Peak. The calculated mean vertical column abundances, excluding the spring observations, are equal to (2.55 +/- 0.30) x 10(15) molec./cm(2) (S.D.) and (2.75 +/- 0.30) x 10(15) molec./cm(2) respectively above the Jungfraujoch and the Kitt Peak observatories. Based on a realistic volume mixing ratio profile, these columns translate into mean volume mixing ratios equal to 190 x 10(-12) ppv at the respective altitudes of the stations. C1 NASA,LANGLEY RES CTR,DIV ATMOSPHER SCI,HAMPTON,VA. RP MAHIEU, E (reprint author), UNIV LIEGE,INST ASTROPHYS,B-4000 LIEGE,BELGIUM. OI Mahieu, Emmanuel/0000-0002-5251-0286 NR 24 TC 31 Z9 31 U1 0 U2 0 PU KLUWER ACADEMIC PUBL PI DORDRECHT PA SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS SN 0167-7764 J9 J ATMOS CHEM JI J. Atmos. Chem. PD MAR PY 1995 VL 20 IS 3 BP 299 EP 310 DI 10.1007/BF00694499 PG 12 WC Environmental Sciences; Meteorology & Atmospheric Sciences SC Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences GA RJ175 UT WOS:A1995RJ17500006 ER PT J AU RIND, D HEALY, R PARKINSON, C MARTINSON, D AF RIND, D HEALY, R PARKINSON, C MARTINSON, D TI THE POLE OF SEA-ICE IN 2X CO2 CLIMATE MODEL SENSITIVITY .1. THE TOTAL INFLUENCE OF SEA-ICE THICKNESS AND EXTENT SO JOURNAL OF CLIMATE LA English DT Article ID LAYER OCEAN MODEL; FEEDBACK AB As a first step in investigating the effects of sea ice changes on the climate sensitivity to doubled atmospheric CO2, the authors use a standard simple sea ice model while varying the sea ice distributions and thicknesses in the control run. Thinner ice amplifies the atmospheric temperature sensitivity in these experiments by about 15% (to a warming of 4.8 degrees C), because it is easier for the thinner ice to be removed as the climate warms. Thus, its impact on sensitivity is similar to that of greater sea ice extent in the control run, which provides more opportunity for sea ice reduction. An experiment with sea ice not allowed to change between the control and doubled CO2 simulations illustrates that the total effect of sea ice on surface air temperature changes, including cloud cover and water vapor feedbacks that arise in response to sea ice variations, amounts to 37% of the temperature sensitivity to the CO2 doubling, accounting for 1.56 degrees C of the 4.17 degrees C global warming. This is about four times larger than the sea ice impact when no feedbacks are allowed. The different experiments produce a range of results for southern high latitudes with the hydrologic budget over Antarctica implying sea level increases of varying magnitude or no change. These results highlight the importance of properly constraining the sea ice response to climate perturbations, necessitating the use of more realistic sea ice and ocean models. C1 COLUMBIA UNIV,LAMONT DOHERTY GEOL OBSERV,PALISADES,NY 10964. COLUMBIA UNIV,DEPT GEOL SCI,PALISADES,NY 10964. GODDARD SPACE FLIGHT CTR,OCEANS & ICE BRANCH,GREENBELT,MD. RP RIND, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. RI Parkinson, Claire/E-1747-2012; Healy, Richard/J-9214-2015 OI Parkinson, Claire/0000-0001-6730-4197; Healy, Richard/0000-0002-5098-8921 NR 32 TC 132 Z9 137 U1 1 U2 3 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAR PY 1995 VL 8 IS 3 BP 449 EP 463 DI 10.1175/1520-0442(1995)008<0449:TROSII>2.0.CO;2 PG 15 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QP483 UT WOS:A1995QP48300007 ER PT J AU POORE, KD WANG, JH ROSSOW, WB AF POORE, KD WANG, JH ROSSOW, WB TI CLOUD LAYER THICKNESSES FROM A COMBINATION OF SURFACE AND UPPER-AIR OBSERVATIONS SO JOURNAL OF CLIMATE LA English DT Article ID CLIMATE; SENSITIVITY; RADIATION; ARCHIVES; MOISTURE; CLUSTERS; OCEAN AB Cloud layer thicknesses are derived from base and top altitudes by combining 14 years (1975-1988) of surface and upper-air observations at 63 sites in the Northern Hemisphere. Rawinsonde observations are employed to determine the locations of cloud-layer top and base by testing for dewpoint temperature depressions below some threshold value. Surface observations serve as quality checks on the rawinsonde-determined cloud properties and provide cloud amount and cloud-type information. The dataset provides layer-cloud amount, cloud type, high, middle, or low height classes, cloud-top heights, base heights and layer thicknesses, covering a range of latitudes from 0 degrees to 80 degrees N. All data comes from land sites: 34 are located in continental interiors, 14 are near coasts, and 15 are on islands. The uncertainties in the derived cloud properties are discussed. For clouds classified by low-, mid-, and high-top altitudes, there are strong latitudinal and seasonal variations in the layer thickness only for high clouds. High-cloud layer thickness increases with latitude and exhibits different seasonal variations in different latitude zones: in summer, high-cloud layer thickness is a maximum in the Tropics but a minimum at high latitudes. For clouds classified into three types by base altitude or into six standard morphological types, latitudinal and seasonal variations in layer thickness are very small. The thickness of the clear surface layer decreases with latitude and reaches a summer minimum in the Tropics and summer maximum at higher latitudes over land, but does not vary much over the ocean. Tropical clouds occur in three base-altitude groups and the layer thickness of each group increases linearly with top altitude. Extratropical clouds exhibit two groups, one with layer thickness proportional to their cloud-top altitude and one with small (less than or equal to 1000 m) layer thickness independent of cloud-top altitude. C1 COLUMBIA UNIV,NASA,GODDARD INST SPACE STUDIES,ATMOSPHER & PLANETARY SCI PROGRAM,NEW YORK,NY 10025. AVION INC,BRIDGETON,MO. RI Rossow, William/F-3138-2015 NR 47 TC 63 Z9 83 U1 0 U2 1 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0894-8755 J9 J CLIMATE JI J. Clim. PD MAR PY 1995 VL 8 IS 3 BP 550 EP 568 DI 10.1175/1520-0442(1995)008<0550:CLTFAC>2.0.CO;2 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QP483 UT WOS:A1995QP48300015 ER PT J AU MAVRIPLIS, DJ AF MAVRIPLIS, DJ TI AN ADVANCING FRONT DELAUNAY TRIANGULATION ALGORITHM DESIGNED FOR ROBUSTNESS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID TESSELLATION AB A new algorithm is described for generating an unstructured mesh about an arbitrary two-dimensional configuration. Mesh points are generated automatically by the algorithm in a manner which ensures a smooth variation of elements, and the resulting triangulation constitutes the Delaunay triangulation of these points. The algorithm combines the mathematical elegance and efficiency of Delaunay triangulation algorithms with the desirable point placement features, boundary integrity, and robustness that are traditionally associated with advancing-front-type mesh generation strategies. The method offers increased robustness over previous algorithms in that it cannot fail, regardless of the initial boundary point distribution and the prescribed cell size distribution throughout the flow-field. (C) 1995 Academic Press, Inc. RP MAVRIPLIS, DJ (reprint author), NASA,LANGLEY RES CTR,ICASE,MAIL STOP 132C,HAMPTON,VA 23665, USA. NR 23 TC 30 Z9 32 U1 0 U2 2 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAR 1 PY 1995 VL 117 IS 1 BP 90 EP 101 DI 10.1006/jcph.1995.1047 PG 12 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA QK448 UT WOS:A1995QK44800009 ER PT J AU COIRIER, WJ POWELL, KG AF COIRIER, WJ POWELL, KG TI AN ACCURACY ASSESSMENT OF CARTESIAN-MESH APPROACHES FOR THE EULER EQUATIONS SO JOURNAL OF COMPUTATIONAL PHYSICS LA English DT Article ID REFINEMENT; DYNAMICS; GRIDS AB A critical assessment of the accuracy of Cartesian-mesh approaches for steady, transonic solutions of the Euler equations of gas dynamics is made. An exact solution of the Euler equations (Ringleb's flow) is used not only to infer the order of the truncation error of the Cartesian-mesh approaches, but also to compare the magnitude of the discrete error directly to that obtained with a structured mesh approach. Uniformly and adaptively refined solutions using a Cartesian-mesh approach are obtained and compared to each other and to uniformly refined structured mesh results. The effect of cell merging is investigated as well as the use of two different K-exact reconstruction procedures, The solution methodology of the schemes is explained and tabulated results are presented to compare the solution accuracies. (C) 1995 Academic Press, Inc. C1 UNIV MICHIGAN,ANN ARBOR,MI 48109. RP COIRIER, WJ (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. OI Powell, Kenneth/0000-0002-3708-8814 NR 31 TC 65 Z9 67 U1 0 U2 3 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0021-9991 J9 J COMPUT PHYS JI J. Comput. Phys. PD MAR 1 PY 1995 VL 117 IS 1 BP 121 EP 131 DI 10.1006/jcph.1995.1050 PG 11 WC Computer Science, Interdisciplinary Applications; Physics, Mathematical SC Computer Science; Physics GA QK448 UT WOS:A1995QK44800012 ER PT J AU KIM, SW ZAMAN, KBMQ PANDA, J AF KIM, SW ZAMAN, KBMQ PANDA, J TI NUMERICAL INVESTIGATION OF UNSTEADY TRANSITIONAL FLOW OVER OSCILLATING AIRFOIL SO JOURNAL OF FLUIDS ENGINEERING-TRANSACTIONS OF THE ASME LA English DT Article ID SCALE TURBULENCE MODEL; CROSS-FLOW; CHANNEL AB A numerical investigation of unsteady transitional flow over an oscillating NACA 0012 airfoil at a Reynolds number of 44,000 and reduced frequency of 0.2 is carried our and the results are compared with experimental data. The Navier-Stokes equations defined on arbitrary Lagrangian-Eulerian coordinates are solved by a time-accurate finite volume method that incorporates an incremental pressure equation for the conservation of mass. The transitional turbulence field is described by multiple-time-scale turbulence equations. The numerical method successfully predicts the large dynamic stall vortex (DSV) and the trailing edge vortex (TEV) that are periodically generated by the oscillating airfoil. The numerical results shore that the transition from laminar to turbulent state and relaminarization occur widely in time and in space. The calculated streaklines and the ensemble-averaged velocity profiles are in good agreement with the measured data. RP KIM, SW (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 23 TC 2 Z9 2 U1 1 U2 2 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 1995 VL 117 IS 1 BP 10 EP 16 DI 10.1115/1.2816799 PG 7 WC Engineering, Mechanical SC Engineering GA QP809 UT WOS:A1995QP80900006 ER PT J AU FEYNMAN, J MARTIN, SF AF FEYNMAN, J MARTIN, SF TI THE INITIATION OF CORONAL MASS EJECTIONS BY NEWLY EMERGING MAGNETIC-FLUX SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID RECONNECTION; TRANSIENTS; FLARES; FIELDS AB We present observational evidence that eruptions of quiescent filaments and associated coronal mass ejections (CMEs) occur as a consequence of the destabilization of large-scale coronal arcades due to interactions between these structures and new and growing active regions. Both statistical and case studies have been carried out. In a case study of a ''bugle'' observed by the High-Altitude Observatory Solar Maximum Mission coronagraph, the high-resolution magnetograms from the Big Bear Solar Observatory show newly emerging and rapidly changing flux in the magnetic fields that apparently underlie the bugle. For other case studies and in the statistical work the eruption of major quiescent filaments was taken as a proxy for CME eruption. We have found that two thirds of the quiescent-filament-associated CMEs occurred after substantial amounts of new magnetic flux emerged in the vicinity of the filament. In addition, in a study of all major quiescent filaments and active regions appearing in a 2-month period we found that 17 of the 22 filaments that were associated with new active regions erupted and 26 of the 31 filaments that were not associated with new Aux did not erupt. In all cases in which the new flux was oriented favorably for reconnection with the preexisting large-scale coronal arcades; the filament was observed to erupt. The appearance of the new flux in the form of new active regions begins a few days before the eruption and typically is still occurring at the time of the eruption. A CME initiation scenario taking account of these observational results is proposed. C1 CALTECH, DEPT SOLAR ASTRON, PASADENA, CA USA. RP CALTECH, JET PROP LAB, 4800 OAK GROVE DR, MAIL STOP 169-506, PASADENA, CA 91109 USA. NR 50 TC 206 Z9 210 U1 1 U2 2 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-9380 EI 2169-9402 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD MAR 1 PY 1995 VL 100 IS A3 BP 3355 EP 3367 DI 10.1029/94JA02591 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL214 UT WOS:A1995QL21400001 ER PT J AU GAZIS, PR AF GAZIS, PR TI SYNOPTIC MAPS OF SOLAR-WIND PARAMETERS FROM IN-SITU SPACECRAFT OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID HELIOSPHERIC CURRENT SHEET; COROTATING STREAM FRONTS; LATITUDE DEPENDENCE; LONGITUDE STRUCTURE; MULTI-SPACECRAFT; SECTOR STRUCTURE; ECLIPTIC-PLANE; VELOCITY; SPEED; PIONEER AB Solar wind observations from the IMP 8 and Pioneer Venus Orbiter (PVO) spacecraft from 1982 until 1988 are combined to construct synoptic maps of solar wind parameters near 1 AU. Each map consists of 6 months of hourly averaged solar wind data, binned by heliographic latitude and Carrington longitude and projected back to the Sun. These maps show the structure and time evolution of solar wind streams near 1 AU in the heliographic latitudes of +/-7.25 degrees and provide an explicit picture of several phenomena, such as gradients, changes in the inclination of the heliospheric current sheet, and the relative positions of various structures in the inner heliosphere, that is difficult to obtain from single-spacecraft observations. The stream structure varied significantly during the last solar cycle. Between 1982 and early 1985, solar wind parameters did not depend strongly on heliographic latitude. During the last solar minimum, the solar wind developed significant latitudinal structure, and high-speed streams were excluded from the vicinity of the solar equator. The interplanetary magnetic field was strongly correlated with the coronal field, and the current sheet tended to coincide with the coronal neutral line. The solar wind speed showed the expected correlations with temperature, interplanetary magnetic field, and distance from the current sheet. The solar wind speed was anticorrelated with density, but the regions of highest density occurred east of the heliospheric current sheet and the regions of lowest solar wind speed. This is consistent with compression at the leading edge of high-speed streams. RP GAZIS, PR (reprint author), NASA, AMES RES CTR, SAN JOSE STATE UNIV FDN, MS 245-3, MOFFETT FIELD, CA 94035 USA. NR 43 TC 6 Z9 6 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0148-0227 J9 J GEOPHYS RES-SPACE JI J. Geophys. Res-Space Phys. PD MAR 1 PY 1995 VL 100 IS A3 BP 3383 EP 3393 DI 10.1029/94JA02629 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL214 UT WOS:A1995QL21400003 ER PT J AU RUZMAIKIN, AA FEYNMAN, J GOLDSTEIN, BE SMITH, EJ BALOGH, A AF RUZMAIKIN, AA FEYNMAN, J GOLDSTEIN, BE SMITH, EJ BALOGH, A TI INTERMITTENT TURBULENCE IN SOLAR-WIND FROM THE SOUTH POLAR HOLE SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERPLANETARY MAGNETIC-FIELD; VELOCITY FLUCTUATIONS; ULYSSES; AU AB The magnetic fields measured by the Ulysses spacecraft are used to study solar wind turbulence in the fast solar wind from the south polar hole. The spacecraft was at about 46 deg south latitude and 3.9 AU. For a magnetic field with a Gaussian distribution the power spectrum (second-order structure function) is sufficient to completely characterize the turbulence. However, the actual distribution is non-Gaussian so that the effects of intermittency must be taken into account. The observed spectral exponents include effects of intermittency and cannot be directly compared with the standard second-order spectral theories such as the Kolmogorov and Kraichnan theories. To permit a better comparison of the observations with the theoretical models, we study the structure characteristics of the data. We find the exponents of the second-order structure functions (power spectra) and the higher-order normalized structure functions for the components of the magnetic fields. We show that these sets of exponents can be approximately described by two basic numbers: the spectral exponent and the intermittency exponent. The intermittency exponent characterizes correlation properties of the energy cascade from large to small scales. Before comparing the observations to the theoretically expected values, a reduction must be made to the observed spectral exponent. The amount of the reduction depends on both the intermittency exponent and the model of the energy cascade assumed in the turbulence theory. We reduce the measured spectral indices according to a simple model for Alfven turbulence that is described here. We then compare our reduced spectral indices with second-order spectral theory. The reduced spectral indices for the period range of 1 min to about a half hour are remarkably constant and in good agreement with the value of 3/2. Thus our treatment is self-consistent, Our tentative conclusion is that the high-frequency turbulence appears to agree with the model of random-phased Alfven waves. This tentative conclusion must be tested by further theoretical and observational work. C1 UNIV LONDON IMPERIAL COLL SCI TECHNOL & MED,BLACKETT LAB,LONDON SW7 2BZ,ENGLAND. CALIF STATE UNIV NORTHRIDGE,DEPT PHYS & ASTRON,NORTHRIDGE,CA. RP RUZMAIKIN, AA (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 28 TC 63 Z9 63 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 1995 VL 100 IS A3 BP 3395 EP 3403 DI 10.1029/94JA02808 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL214 UT WOS:A1995QL21400004 ER PT J AU ROBERTS, DA WILTBERGER, MJ AF ROBERTS, DA WILTBERGER, MJ TI NONEQUILIBRIUM, LARGE-AMPLITUDE MHD FLUCTUATIONS IN THE SOLAR-WIND SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID ALFVEN WAVES; HYDROMAGNETIC-WAVES; MAGNETIC-FIELD; TURBULENCE; ACCELERATION; PROPAGATION; EVOLUTION; MAGNETOFLUID; INSTABILITY; TEMPERATURE AB Compressible MHD simulations in one dimension with three-dimensional vectors are used to investigate a number of processes relevant to problems in interplanetary physics, The simulations indicate that a large-amplitude nonequilibrium (e.g., linearly polarized) Alfvenic wave, which always starts with small relative fluctuations in the magnitude B of the magnetic field, typically evolves to flatten the magnetic profile in most regions. Under a wide variety of conditions B and the density rho become anticorrelated on average, If the mean magnetic field is allowed to decrease in time, the point where the transverse magnetic fluctuation amplitude delta B-T is greater than the mean field B-0 is not special, and large values of delta B-T/B-0 do not cause the compressive thermal energy to increase remarkably or the wave energy to dissipate at an unusually high rate. Nor does the ''backscatter'' of the waves that occurs when the sound speed is less than the Alfven speed result, in itself, in substantial energy dissipation, but rather primarily in a phase change between the magnetic and velocity fields, For isolated wave packets the backscatter does not occur for any of the parameters examined; an initial radiation of acoustic waves away from the packet establishes a stable traveling structure. Thus these simulations, although greatly idealized compared to reality, suggest a picture in which the interplanetary fluctuations should have small delta B and increasingly quasi-pressure balanced compressive fluctuations, as observed, and in which the dissipation and ''saturation'' at delta B-T/B-0 approximate to 1 required by some theories of wave acceleration of the solar wind do not occur. The simulations also provide simple ways to understand the processes of nonlinear steepening and backscattering of of Alfven waves and demonstrate the existence of previously unreported types of quasi-steady MHD states. C1 UNIV MARYLAND,DEPT PHYS,COLLEGE PK,MD 20742. RP ROBERTS, DA (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,CODE 692,GREENBELT,MD 20771, USA. RI Wiltberger, Michael/B-8781-2008; Roberts, Dana/D-4625-2012 OI Wiltberger, Michael/0000-0002-4844-3148; NR 27 TC 18 Z9 18 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 1995 VL 100 IS A3 BP 3405 EP 3415 DI 10.1029/94JA02861 PG 11 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL214 UT WOS:A1995QL21400005 ER PT J AU THEJAPPA, G WENTZEL, DG STONE, RG AF THEJAPPA, G WENTZEL, DG STONE, RG TI LOW-FREQUENCY WAVES ASSOCIATED WITH LANGMUIR-WAVES IN SOLAR-WIND SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID III RADIO-BURSTS; MARCH 1991; PLASMA; TURBULENCE; ULYSSES; COLLAPSE; EMISSION AB The Ulysses spacecraft has detected several events of low-frequency electromagnetic waves in association with Langmuir waves in the solar wind. The high time resolution observations show that the Langmuir waves are very intense and occur as broad peaks superposed by collapsing millisecond spikes. The low-frequency waves are identified as electromagnetic lower hybrid waves. The observed energy densities of these waves often exceed the strong turbulence thresholds. It is shown that none of the parametric decay instabilities involving Langmuir and low-frequency waves are energetically favorable to explain the present observations. The low-frequency waves are proposed to arise from currents associated with gradients in the electron beam originating at sites where Langmuir waves scatter the beam electrons. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. RP THEJAPPA, G (reprint author), UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742, USA. NR 31 TC 28 Z9 28 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 1995 VL 100 IS A3 BP 3417 EP 3426 DI 10.1029/94JA03237 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL214 UT WOS:A1995QL21400006 ER PT J AU NERNEY, S SUESS, ST SCHMAHL, EJ AF NERNEY, S SUESS, ST SCHMAHL, EJ TI FLOW DOWNSTREAM OF THE HELIOSPHERIC TERMINAL SHOCK - MAGNETIC-FIELD LINE TOPOLOGY AND SOLAR-CYCLE IMPRINT SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID INTERSTELLAR-MEDIUM; WIND INTERACTION AB The topology of the magnetic field in the heliosheath is illustrated using plots of the field lines. It is shown that the Archimedean spiral inside the terminal shock is rotated back in the heliosheath into nested spirals that are advected in the direction of the interstellar wind. The 22-year solar magnetic cycle is imprinted onto these field lines in the form of unipolar magnetic envelopes surrounded by volumes of strongly mixed polarity, Each envelope is defined by the changing tilt of the heliospheric current sheet, which is in turn defined by the boundary of unipolar high-latitude regions on the Sun that shrink to the pole at solar maximum and expand to the equator at solar minimum. The detailed shape of the envelopes is regulated by the solar wind velocity structure in the heliosheath. C1 UNIV MARYLAND,DEPT ASTRON,COLLEGE PK,MD 20742. RP NERNEY, S (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,ES82,HUNTSVILLE,AL 35812, USA. NR 23 TC 35 Z9 35 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAR 1 PY 1995 VL 100 IS A3 BP 3463 EP 3471 DI 10.1029/94JA02690 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL214 UT WOS:A1995QL21400011 ER PT J AU VASSILIADIS, D KLIMAS, AJ BAKER, DN ROBERTS, DA AF VASSILIADIS, D KLIMAS, AJ BAKER, DN ROBERTS, DA TI A DESCRIPTION OF THE SOLAR-WIND MAGNETOSPHERE COUPLING BASED ON NONLINEAR FILTERS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID GEOMAGNETIC-ACTIVITY; TIME-SERIES; SUBSTORMS; MAGNETOTAIL; RECONSTRUCTION; INDEXES; CHAOS; FIELD; MODEL AB A nonlinear filtering method is introduced for the study of the solar wind - magnetosphere coupling and related to earlier linear techniques. The filters are derived from the magnetospheric state, a representation of the magnetospheric conditions in terms of a few global variables, here the auroral electrojet indices. The filters also couple to the input, a representation of the solar wind variables, here the rectified electric field. Filter-based iterative prediction of the indices has been obtained for up to 20 hours. The prediction is stable with respect to perturbations in the initial magnetospheric state; these decrease exponentially at the rate of 30 min(-1). The performance of the method is examined for a wide range of parameters and is superior to that of other linear and nonlinear techniques. In the magnetospheric state representation the coupling is modeled as a small number of nonlinear equations under a time-dependent input. C1 UNIV COLORADO,ATMOSPHER & SPACE PHYS LAB,BOULDER,CO 80309. RP VASSILIADIS, D (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. RI Roberts, Dana/D-4625-2012 NR 74 TC 148 Z9 148 U1 1 U2 3 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES JI J. Geophys. Res-Space Phys. PD MAR 1 PY 1995 VL 100 IS A3 BP 3495 EP 3512 DI 10.1029/94JA02725 PG 18 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL214 UT WOS:A1995QL21400015 ER PT J AU SUNDARAM, AK FAIRFIELD, DH AF SUNDARAM, AK FAIRFIELD, DH TI LOCALIZED TEARING MODES IN THE MAGNETOTAIL DRIVEN BY CURVATURE EFFECTS SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID STABILITY; PLASMAS; INSTABILITY; SHEET AB The stability of collisionless tearing modes is examined in the presence of curvature drift resonances and the trapped particle effects. A kinetic description for both electrons and ions is employed to investigate the stability of a two-dimensional equilibrium model. The main features of the study are to treat the ion dynamics properly by incorporating effects associated with particle trajectories in the tail fields and to include the linear coupling of trapped particle modes. Generalized dispersion relations are derived in several parameter regimes by considering two important sublayers of the reconnecting region. For a typical choice of parameters appropriate to the current sheet region, we demonstrate that localized tearing modes driven by ion curvature drift resonance effects are excited in the current sheet region with growth time of the order of a few seconds. Also, we examine nonlocal characteristics of tearing modes driven by curvature effects and show that modes growing in a fraction of a second arise when mode widths are larger than the current sheet width. Further, we show that trapped particle effects, in an interesting frequency regime, significantly enhance the growth rate of the tearing mode. The relevance of this theory for substorm onset phase and other features of the substorms is briefly discussed. RP SUNDARAM, AK (reprint author), NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771, USA. NR 38 TC 11 Z9 11 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 1995 VL 100 IS A3 BP 3563 EP 3572 DI 10.1029/94JA03242 PG 10 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL214 UT WOS:A1995QL21400021 ER PT J AU FEDDER, JA LYON, JG SLINKER, SP MOBARRY, CM AF FEDDER, JA LYON, JG SLINKER, SP MOBARRY, CM TI TOPOLOGICAL-STRUCTURE OF THE MAGNETOTAIL AS A FUNCTION OF INTERPLANETARY MAGNETIC-FIELD DIRECTION SO JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS LA English DT Article ID SOLAR-WIND; MAGNETOPAUSE RECONNECTION; ELECTRIC-FIELD; MAGNETOSPHERE; ENERGY; VOLTAGE; MODELS AB Magnetic reconnection between the interplanetary magnetic field (IMF) and the geomagnetic field is thought to play a major role in the transfer of solar wind momentum and energy to the magnetosphere. As the angle between the IMF and the geomagnetic field is changed at the bow of the magnetosphere, the topological record of the location of the reconnection region should be recorded in the magnetosheath and on the magnetopause along the flanks of the tail, because the super fast how freezes strong magnetic gradients formed in the bow reconnection regions into the plasma downstream. In this report, we present results from a three-dimensional, magnetohydrodynamic (MHD), global numerical simulation code for the location of the separatrix between unconnected IMF magnetosheath field lines and reconnected field lines which penetrate the magnetopause and connect to the polar ionosphere. The angle between the IMF direction and the line where the separatrix crosses the magnetopause is shown to be a sensitive function of the IMF clock angle. We also explain how this behavior can be used to derive an approximate relation for the dependence of the cross-polar voltage on the IMF clock angle. We conclude with a note of caution concerning the importance of physical boundary conditions in magnetoplasma simulations. C1 SFA INC,LANDOVER,MD. DARTMOUTH COLL,DEPT PHYS & ASTRON,HANOVER,NH. NASA,GODDARD SPACE FLIGHT CTR,CTR COMPUTAT SCI,GREENBELT,MD 20771. RP FEDDER, JA (reprint author), USN,RES LAB,DIV PLASMA PHYS,BEAM PHYS BRANCH,CODE 4790,WASHINGTON,DC 20375, USA. NR 31 TC 113 Z9 117 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 1995 VL 100 IS A3 BP 3613 EP 3621 DI 10.1029/94JA02577 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QL214 UT WOS:A1995QL21400025 ER PT J AU BUKLEY, AP AF BUKLEY, AP TI HUBBLE-SPACE-TELESCOPE POINTING CONTROL-SYSTEM DESIGN IMPROVEMENT STUDY RESULTS SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Unexpected thermally induced disturbances originating in the solar arrays imposed deleterious effects on the pointing performance of the Hubble Space Telescope (HST). A NASA redesign of the onboard pointing control system (PCS) brought the performance back into specification during a majority of the orbit time. As a result of this controller redesign effort, a wealth of flight data was collected and control design simulation models enhanced. Under sponsorship of the NASA Controls/Structures Interaction Program at the Marshall Space Flight Center, a study was conducted to determine if performance improvements could be obtained when advanced modern control techniques under study in the program were applied to the HST PCS. Five modern control techniques were applied to the problem. Flight data and simulation models were provided to the research teams. The methods considered were reduced-order model-based control, linear-quadratic-Gaussian-based control, analytically and numerically derived H-infinity control, covariance control, and dual-mode disturbance-accommodating control design. The performance of these designs was tested in a government-furnished nonlinear simulation of the HST. In general, some performance improvements over the NASA redesigned controller were seen in the simulation studies. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI & APPLICAT GRP,HUNTSVILLE,AL 35812. RP BUKLEY, AP (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,HUBBLE SPACE TELESCOPE DESIGN IMPROVEMENT STUDY,HUNTSVILLE,AL 35812, USA. NR 33 TC 11 Z9 11 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 1995 VL 18 IS 2 BP 194 EP 199 DI 10.2514/3.21369 PG 6 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QU336 UT WOS:A1995QU33600002 ER PT J AU NURRE, GS SHARKEY, JP NELSON, JD BRADLEY, AJ AF NURRE, GS SHARKEY, JP NELSON, JD BRADLEY, AJ TI PRESERVICING MISSION, ON-ORBIT MODIFICATIONS TO HUBBLE-SPACE-TELESCOPE POINTING CONTROL-SYSTEM SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Because of unexpected, thermally induced disturbances originating in the solar arrays (SAs), the Hubble Space Telescope was initially unable to meet its pointing error specifications of 0.007 arc-s [root mean square] for observations lasting from a few seconds to several hours. The effort to pinpoint the mechanism causing the problem and to redesign the onboard controller to accommodate the disturbance began shortly after deployment. After controller modifications, the pointing errors were well within the specification for all of the orbit except for short intervals during transitions in and out of Earth's shadow. This paper presents a chronology of the redesign process and night data showing the achieved pointing performance. During the recent servicing mission (December 1993) the SAs were replaced with arrays of a modified mechanical design. A preliminary assessment of pointing performance since that time is presented. C1 LOCKHEED MISSILES & SPACE CO INC,ORG 7416,SUNNYVALE,CA 94089. ALLIED SIGNAL AEROSP CO,HST POINTING CONTROL SYST,ANNAPOLIS,MD 20701. RP NURRE, GS (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,STRUCT & DYNAM LAB ED01,PRECIS POINTING SYST BRANCH ED12,HUNTSVILLE,AL 35812, USA. NR 13 TC 11 Z9 16 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 1995 VL 18 IS 2 BP 222 EP 229 DI 10.2514/3.21373 PG 8 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QU336 UT WOS:A1995QU33600006 ER PT J AU KETCHUM, EA TOLSON, RH AF KETCHUM, EA TOLSON, RH TI ONBOARD STAR IDENTIFICATION WITHOUT A-PRIORI ATTITUDE INFORMATION SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB Many algorithms used today determine spacecraft attitude by identifying stars in the field of view of a star tracker. However each of these methods require some a priori knowledge of the spacecraft attitude. Some algorithms have been extended to implement a computation-intense full-sky scan. Others require large data bases. Both storage and speed are concerns for autonomous onboard systems. This paper presents an algorithm that, by discretizing the sky and filtering by visual magnitude of the brightest observed star, provides a star identification process that is computationally efficient, compared to existing techniques. A savings in onboard storage of over 80% compared with a popular existing technique is documented. Results of random tests with simulated star fields are presented without false identification and with dramatic increase in speed over full-sky scan methods. C1 NASA,GODDARD SPACE FLIGHT CTR,DIV FLIGHT DYNAM,GREENBELT,MD 20771. GEORGE WASHINGTON UNIV,JOINT INST ADVANCEMENT FLIGHT SCI,HAMPTON,VA 23681. NR 14 TC 15 Z9 17 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 1995 VL 18 IS 2 BP 242 EP 246 DI 10.2514/3.21376 PG 5 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QU336 UT WOS:A1995QU33600009 ER PT J AU MARKLEY, FL BAUER, FH DEILY, JJ FEMIANO, MD AF MARKLEY, FL BAUER, FH DEILY, JJ FEMIANO, MD TI ATTITUDE-CONTROL SYSTEM CONCEPTUAL DESIGN FOR GEOSTATIONARY OPERATIONAL ENVIRONMENTAL SATELLITE SPACECRAFT SERIES SO JOURNAL OF GUIDANCE CONTROL AND DYNAMICS LA English DT Article AB The next generation of the Geostationary Operational Environmental Satellite (GOES-N) will require extremely stringent pointing performance for improved weather prediction. These spacecraft will employ high-precision gyros and star trackers in a unique control system design concept to achieve the end-to-end pointing performance at the focal plane of the instruments. This paper presents the GOES-N attitude control system conceptual design, sensor complement trade-offs, attitude determination theory, and system performance expectations. RP MARKLEY, FL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,GUIDANCE & CONTROL BRANCH,CODE 712,GREENBELT,MD 20771, USA. NR 12 TC 4 Z9 10 U1 0 U2 3 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0731-5090 J9 J GUID CONTROL DYNAM JI J. Guid. Control Dyn. PD MAR-APR PY 1995 VL 18 IS 2 BP 247 EP 255 DI 10.2514/3.21377 PG 9 WC Engineering, Aerospace; Instruments & Instrumentation SC Engineering; Instruments & Instrumentation GA QU336 UT WOS:A1995QU33600010 ER PT J AU PALMER, MT LACK, AM LYNCH, JC AF PALMER, MT LACK, AM LYNCH, JC TI COMMUNICATION CONFLICTS OF STATUS AND AUTHORITY IN DYADIC, TASK-BASED INTERACTIONS - STATUS GENERALIZATION IN AIRPLANE COCKPITS SO JOURNAL OF LANGUAGE AND SOCIAL PSYCHOLOGY LA English DT Article AB Status generalization theory predicts that high-status individuals will automatically assume high-authority roles controlling task-based interactions. However, temporary task demands may require low-status individuals to assume high-authority positions. If status generalizes, role conflicts may occur when high-status partners fail to yield control to low-status partners. To test status generalization in legitimate role-reversal situations, airplane pilot crews who represented high- and low-status partners (i.e., captains and first officers) flew simulated missions during which transfers of authority (i.e., pilot flying to pilot not flying) occurred. Results showed captains initiated more transfers and used more direct commands in initiations of transfers of authority than did first officers, even when captains were in, low-authority roles. Only when using mitigated commands did first officers in high-authority positions initiate more transfers than did captains. Performative speech acts were shown to be effective, conventional devices for enacting transfers of authority. C1 SAN JOSE STATE UNIV,SAN JOSE,CA. NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP PALMER, MT (reprint author), NORTHWESTERN UNIV,EVANSTON,IL 60208, USA. NR 32 TC 3 Z9 3 U1 1 U2 1 PU SAGE PUBL INC PI THOUSAND OAKS PA 2455 TELLER RD, THOUSAND OAKS, CA 91320 SN 0261-927X J9 J LANG SOC PSYCHOL JI J. Lang. Soc. Psychol. PD MAR PY 1995 VL 14 IS 1-2 BP 85 EP 101 DI 10.1177/0261927X95141005 PG 17 WC Communication; Linguistics; Psychology, Social SC Communication; Linguistics; Psychology GA QY277 UT WOS:A1995QY27700005 ER PT J AU COOK, AL HENDRICKS, HD AF COOK, AL HENDRICKS, HD TI CHARACTERISTICS OF LINEWIDTH-NARROWED DISTRIBUTED-BRAGG-REFLECTOR LASER WITH A FIBER EXTERNAL-CAVITY FORMED WITH THE VERTICAL GRATING EMISSION SO JOURNAL OF LIGHTWAVE TECHNOLOGY LA English DT Article ID SEMICONDUCTOR-LASERS; SPECTRAL LINEWIDTH; FEEDBACK LASERS; MODULATION CHARACTERISTICS; FREQUENCY-MODULATION; OPTICAL FEEDBACK; INJECTION-LASERS; INTENSITY NOISE; COUPLED-CAVITY; REDUCTION AB Linewidth reduction has been observed in a distributed Bragg reflector (DBR) laser with a second-order grating when an external cavity is formed with the vertical emission. The external cavity consists of a length of optical fiber which is brought close to the top of the laser. Displayed linewidths low as 26 kHz have been measured. To the authors' knowledge, this is the first report of linewidth reduction via vertical emission from a laser diode. RP COOK, AL (reprint author), NASA,LANGLEY RES CTR,HAMPTON,VA 23681, USA. NR 44 TC 0 Z9 0 U1 1 U2 1 PU IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC PI NEW YORK PA 345 E 47TH ST, NEW YORK, NY 10017-2394 SN 0733-8724 J9 J LIGHTWAVE TECHNOL JI J. Lightwave Technol. PD MAR PY 1995 VL 13 IS 3 BP 356 EP 363 DI 10.1109/50.372429 PG 8 WC Engineering, Electrical & Electronic; Optics; Telecommunications SC Engineering; Optics; Telecommunications GA QP051 UT WOS:A1995QP05100003 ER PT J AU GAMACHE, RR NESHYBA, SP PLATEAUX, JJ BARBE, A REGALIA, L POLLACK, JB AF GAMACHE, RR NESHYBA, SP PLATEAUX, JJ BARBE, A REGALIA, L POLLACK, JB TI CO2-BROADENING OF WATER-VAPOR LINES SO JOURNAL OF MOLECULAR SPECTROSCOPY LA English DT Article ID ROTATION-VIBRATION LINES; ASYMMETRIC-TOP MOLECULES; N-2-BROADENED HALFWIDTHS; TEMPERATURE-DEPENDENCE; H2O-CO2 MIXTURES; PURE ROTATION; VENUS; H2O; INTENSITIES; WIDTHS AB Measurements of CO2-broadened half-widths of 31 transitions belonging to the v(1), 2v(2), and v(3) bands of water vapor were made at T = 294.4 K. Calculations following the formalism of Robert and Bonamy with an electrostatic and atom-atom interaction potential and dynamics correct to second order in time were performed for 562 transitions relevant to the 1- to 2.5-mu m region. The calculations were compared with the measurements made in this work, a recent study by Langlois et al. (J. iMol. Spectrosc. 167, 272-281, 1994), and an earlier work by Varanasi et al. (J. Quant. Spectrosc. Radiat. Transfer. 11, 223-230, 1971). The calculations compared with experiment show average percent differences of +12, +1.5, and -8, respectively, for the works listed above. Unfortunately there are no common lines measured by the different groups so a direct comparison of the measurements is not possible. Calculations of the temperature dependence of the halfwidths were made for 34 transitions. The temperature dependence of the half-widths determined from theory and the measurements of Langlois et al. agree reasonably well with two exceptions. (C) 1995 Academic Press, Inc. C1 UNIV REIMS,SPECTROMETRIE MOLEC & ATMOSPHER LAB,CNRS,URA 1434,F-51062 REIMS,FRANCE. NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP GAMACHE, RR (reprint author), UNIV MASSACHUSETTS,LOWELL CTR ATMOSPHER RES,450 AIKEN ST,LOWELL,MA 01854, USA. NR 48 TC 46 Z9 46 U1 0 U2 4 PU ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS PI SAN DIEGO PA 525B STREET, SUITE 1900, SAN DIEGO, CA 92101-4495 SN 0022-2852 J9 J MOL SPECTROSC JI J. Mol. Spectrosc. PD MAR PY 1995 VL 170 IS 1 BP 131 EP 151 DI 10.1006/jmsp.1995.1060 PG 21 WC Physics, Atomic, Molecular & Chemical; Spectroscopy SC Physics; Spectroscopy GA QL001 UT WOS:A1995QL00100009 ER PT J AU TRZEBSKI, A SMITH, ML BEIGHTOL, LA FRITSCHYELLE, JM REA, RF ECKBERG, DL AF TRZEBSKI, A SMITH, ML BEIGHTOL, LA FRITSCHYELLE, JM REA, RF ECKBERG, DL TI MODULATION OF HUMAN SYMPATHETIC PERIODICITY BY MILD, BRIEF HYPOXIA AND HYPERCAPNIA SO JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY LA English DT Article DE HYPOXIA; HYPERCAPNIA; SYMPATHETIC MICRONEUROGRAPHY; SINUS ARRHYTHMIA ID SLEEP-APNEA; NERVE RESPONSES; CHEMORECEPTORS; HYPERTENSION; DISCHARGE; NOREPINEPHRINE; VENTILATION; TACHYCARDIA; STIMULATION; ACTIVATION AB We determined the influence of brief mild normocapnic hyperoxia, hypoxia, and hyperoxic hypercapnia on human muscle sympathetic nerve activity and R-R intervals, as quantified by both time- and frequency-domain analyses. We obtained measurements in nine healthy young adult men and women during uncontrolled and frequency (but not tidal volume) controlled breathing. Responses were evaluated with forward selection and backward elimination statistical models, with muscle sympathetic nerve activity as the dependent variable, and power spectral techniques. Hyperoxia and hypoxia did not alter arterial pressure; hypercapnia increased diastolic pressure modestly. Average R-R intervals tended to increase during hyperoxia, and decrease during hypoxia and hypercapnia. During uncontrolled breathing, changes of inspiratory gases exerted only minor effects on muscle sympathetic nerve activity; during controlled breathing, both hypoxia and hypercapnia tended to increase muscle sympathetic nerve activity. Statistical modeling suggested that chemoreceptor stimulation increased muscle sympathetic neural outflows, but that increases of sympathetic traffic were opposed by secondary increases of ventilation. Inspiratory gases modulated the frequency distribution of muscle sympathetic nerve activity strikingly: hypoxia increased sympathetic power at respiratory frequencies and hypercapnia increased sympathetic power at both respiratory and (primarily in one subject) cardiac frequencies. Our data suggest that mild brief hypoxia and hypercapnia increase human muscle sympathetic nerve activity, but that this tendency is opposed by chemoreflex-induced increases of ventilation. Our results suggest also that chemoreceptor activity exerts important influences on the frequency content, as well as the quantity of sympathetic neural outflow. C1 HUNTER HOLMES MCGUIRE DEPT VET AFFAIRS MED CTR,DEPT PHYSIOL,RICHMOND,VA 23249. VIRGINIA COMMONWEALTH UNIV,MED COLL VIRGINIA,RICHMOND,VA 23298. MED ACAD WARSAW,INST PHYSIOL SCI,DEPT PHYSIOL,WARSAW,POLAND. CASE WESTERN RESERVE UNIV,DEPT MED,CLEVELAND,OH 44106. NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. MAYO CLIN,SCOTTSDALE,AZ. RP TRZEBSKI, A (reprint author), HUNTER HOLMES MCGUIRE DEPT VET AFFAIRS MED CTR,DEPT MED,RICHMOND,VA 23249, USA. FU NHLBI NIH HHS [HL-07580, HL-22296] NR 48 TC 13 Z9 15 U1 0 U2 0 PU POLISH PHYSIOLOGICAL SOC PI GRZEGORZECKA PA JAGIELLONIAN UNIV SCHOOL MED, INST PHYSIOLOGY, 31-531 KRAKOW, 16 GRZEGORZECKA, POLAND SN 0867-5910 J9 J PHYSIOL PHARMACOL JI J. Physiol. Pharmacol. PD MAR PY 1995 VL 46 IS 1 BP 17 EP 35 PG 19 WC Physiology SC Physiology GA RQ389 UT WOS:A1995RQ38900002 PM 7599334 ER PT J AU BUFFUM, DH AF BUFFUM, DH TI BLADE ROW INTERACTION EFFECTS ON FLUTTER AND FORCED RESPONSE SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibition CY JUN 28-30, 1993 CL MONTEREY, CA SP Amer Inst Aeronaut & Astronaut, Soc Automot Engineers, Amer Soc Mech Engineers, Amer Soc Engn Educ ID ROTOR STATOR INTERACTION AB A procedure to calculate intrablade row unsteady aerodynamic interactions is developed that relies upon results from isolated blade row unsteady aerodynamic analyses. Using influence coefficients that express the unsteady forces on one blade row due to the motion of another, an aeroelastic model is obtained that accounts for the coupling of the vibratory responses of multiple blade rows. The model is applied to two model configurations, each consisting of three blade rows. The flutter analysis shows that interaction effects can be destabilizing, and the forced response analysis shows that interaction effects can result in a significant increase in the resonant response of a blade row. RP BUFFUM, DH (reprint author), NASA,LEWIS RES CTR,DIV PROPULS SYST,TURBOMACHINERY TECHNOL BRANCH,CLEVELAND,OH 44135, USA. NR 14 TC 6 Z9 7 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 1995 VL 11 IS 2 BP 205 EP 212 DI 10.2514/3.51412 PG 8 WC Engineering, Aerospace SC Engineering GA QM084 UT WOS:A1995QM08400003 ER PT J AU STEPHENS, MA RIMLINGER, MJ SHIH, TIP AF STEPHENS, MA RIMLINGER, MJ SHIH, TIP TI CHIMERA GRIDS IN COMPUTING FLOWFIELDS IN TURBINE-BLADE-INTERNAL-COOLANT PASSAGES SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibition CY JUN 28-30, 1993 CL MONTEREY, CA SP Amer Inst Aeronaut & Astronaut, Soc Automot Engineers, Amer Soc Mech Engineers, Amer Soc Engn Educ ID HEAT-TRANSFER AB When computing flows inside geometrically complex turbine-blade coolant passages, the structure of the grid system used ran significantly affect the overall time and cost required to obtain solutions, This article addresses this issue while evaluating and developing computational tools for the design and analysis of coolant-passages, and is divided into two parts. In the first part, the various types of structured and unstructured grids are compared in relation to their ability to provide solutions in a timely and cost-effective manner. This comparison shows that the overlapping structured grids, known as chimera grids, can rival and in some instances exceed the cost-effectiveness of unstructured grids in terms of both the man hours needed to generate grids and the amount of computer memory and CPU time needed to obtain solutions. In the second part, a computational tool utilizing chimera grids was used to compute the now and heat transfer in two different turbine-blade coolant passages that contain baffles and numerous pin fins. These computations showed the versatility and flexibility offered by chimera grids. C1 NASA,LEWIS RES CTR,TURBOMACHINERY TECHNOL BRANCH,CLEVELAND,OH 44135. RP STEPHENS, MA (reprint author), CARNEGIE MELLON UNIV,DEPT MECH ENGN,PITTSBURGH,PA 15213, USA. NR 21 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 1995 VL 11 IS 2 BP 213 EP 220 DI 10.2514/3.51413 PG 8 WC Engineering, Aerospace SC Engineering GA QM084 UT WOS:A1995QM08400004 ER PT J AU IEK, C BOLDMAN, DR IBRAHIM, M AF IEK, C BOLDMAN, DR IBRAHIM, M TI 3-DIMENSIONAL VISCOUS-FLOW ANALYSIS OF AN ADVANCED DUCTED PROPELLER SUBSONIC INLET SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibition CY JUN 28-30, 1993 CL MONTEREY, CA SP Amer Inst Aeronaut & Astronaut, Soc Automot Engineers, Amer Soc Mech Engineers, Amer Soc Engn Educ AB A time-marching Navier-Stokes code called PARC3D was used to study the three-dimensional viscous flow associated with an advanced ducted propeller (ADP) subsonic inlet at takeoff operating conditions. At a free-stream Mach number of 0.2, experimental data of the ADP inlet model indicated that the flow on the cowl windward lip remained attached at an angle of attack of 25 deg, became unstable at 29 deg, and separated at 30 deg. An experimental through-flow test study (without propeller) using another, but similar, inlet indicated that the separation occurred at an angle of attack a few degrees below the value observed when the inlet was tested with the propeller. This evidence showed that the propeller exerted a favourable effect on the inlet low speed and high angle-of-attack performance. A stationary blockage device was designed and tested with this latter inlet to simulate the propeller effect. The test data showed that the blockage device helped prevent the inlet flow from being separated at angle of attack a few degrees higher than the inlet through-flow, but was 1 deg lower than the inlet with the propeller. In the present numerical study, this flow blockage was modeled via a PARC3D computational boundary condition (BC) called the screen BC. The principle formulation of this BC was based on the ''one-and-half dimensions'' actuator disk theory. This screen BC was prescribed at the inlet propeller face station. Numerical results were obtained for inlet flow calculations with and without the screen BC. The results with the screen BC compared better with the ADP experimental test data than those obtained without the screen BC, particularly when the inlet flow separated. C1 CLEVELAND STATE UNIV,CLEVELAND,OH 44115. RP IEK, C (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 17 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 1995 VL 11 IS 2 BP 236 EP 243 DI 10.2514/3.51416 PG 8 WC Engineering, Aerospace SC Engineering GA QM084 UT WOS:A1995QM08400007 ER PT J AU BARRETT, MJ ABER, GS REITH, TW AF BARRETT, MJ ABER, GS REITH, TW TI SPACE-SHUTTLE SIMPLIFIED LO2 CHECK VALVE DEVELOPMENT TESTS SO JOURNAL OF PROPULSION AND POWER LA English DT Article; Proceedings Paper CT AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibition CY JUN 28-30, 1993 CL MONTEREY, CA SP Amer Inst Aeronaut & Astronaut, Soc Automot Engineers, Amer Soc Mech Engineers, Amer Soc Engn Educ AB The coil spring in a Space Shuttle liquid oxygen check valve failed due to cyclic fatigue in September, 1998. The dual-flapper, swing check valve is used to prevent reverse flow to the Space Shuttle Main Engines. Upon inspection of the failed component, the spring tangs were found to be missing and heavy wear was observe on the i.d. of the spring coils. The fracture surfaces revealed that the metal had been steadily worn away until a simple overload caused the final fracture. A series of flow tests using water and a water/gas mixture was conducted to identify the flow phenomenon that produce the cyclic wear. A Plexiglas(R) outlet housing was utilized to view the flapper behavior under different flow conditions and to aid in high-speed photography. The tests revealed that flow instabilities induced two oscillatory flapper responses: 1) a rocking mode and 2) a chattering mode. Initially, attempts were made to reduce the spring-flapper oscillations. However, the final solution to the problem was a springless configuration that satisfied the valve's design requirements and eliminated the oscillations. The springless design relied on the inherent ability of the reverse flow momentum to close the flappers. C1 ROCKWELL INT CORP,DIV SPACE SYST,HOUSTON,TX 77058. RP BARRETT, MJ (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,DIV PROPULS & POWER,PROPULS TEST SECT,HOUSTON,TX 77058, 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 1995 VL 11 IS 2 BP 324 EP 329 DI 10.2514/3.51428 PG 6 WC Engineering, Aerospace SC Engineering GA QM084 UT WOS:A1995QM08400019 ER PT J AU MYERS, RM AF MYERS, RM TI GEOMETRIC SCALING OF APPLIED-FIELD MAGNETOPLASMADYNAMIC THRUSTERS SO JOURNAL OF PROPULSION AND POWER LA English DT Article ID PERFORMANCE; DEPOSITION AB Eight magnetoplasmadynamic thruster configurations were tested with argon propellant at power le, els between 20-130 kW to study the effects of geometry and applied magnetic field strength on thruster performance, The discharge voltage, thrust efficiency, and specific impulse increased monotonically with increasing applied-field strength for all geometries, The highest measured performance was 23% thrust efficiency at 2300-s specific impulse at a power of 113 kW. Both cathode and anode radii fundamentally influenced the efficiency-specific impulse relationship, whereas their lengths influenced only the magnitude of the applied magnetic field required to reach a given performance level, At a given specific impulse, large electrode radii resulted in lower efficiencies, although the rate at which efficiency increased with applied-field strength was higher with larger anode radii. Anode power deposition was the largest efficiency loss, and represented between 50-80% of the input power, The fraction of the input power deposited into the anode decreased with increasing applied-field strength and anode radius. C1 SVERDRUP TECHNOL INC,NASA,LEWIS RES CTR GRP,BROOKPARK,OH 44142. NR 25 TC 2 Z9 3 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 1995 VL 11 IS 2 BP 343 EP 350 DI 10.2514/3.51431 PG 8 WC Engineering, Aerospace SC Engineering GA QM084 UT WOS:A1995QM08400022 ER PT J AU CRUTCHIK, M COLOZZA, AJ APPELBAUM, J AF CRUTCHIK, M COLOZZA, AJ APPELBAUM, J TI PHOTOVOLTAIC CATENARY-TENT ARRAY FOR THE MARTIAN SURFACE SO JOURNAL OF PROPULSION AND POWER LA English DT Article AB To provide electrical power during an exploration mission to Mars, a deployable tent-shaped structure with a flexible photovoltaic (PV) blanket is analyzed. The array is designed with a self-deploying mechanism utilizing pressurized gas expansion. The structural design for the array uses a combination of cables, beam, and columns to support and deploy the PV blanket, Under the force of gravity a cable carrying a uniform load will take the shape of a catenary curve. A catenary-tent collector is self-shadowing, which must be taken into account in the solar radiation calculation. The shape and the area of the shadow on the array has been calculated and used in the determination of the global radiation on the array. The PV blanket shape and structure dimensions were optimized to achieve configuration that maximizes the specific power (W/kg). The optimization was performed for four types of PV blankets (Si, GaAs/Ge, GaAs CLEFT, and amorphous Si), and four types of structural materials (carbon composite, aramid fiber composite, aluminum and magnesium). The combination of carbon composite structural material and GaAs CLEFT solar cells produce the highest specific power. The study was carried out for two sites on Mars corresponding to the Viking lander locations. The designs, were also compared for summer, Hinter, and yearly operation. C1 NASA,LEWIS RES CTR,NATL,CLEVELAND,OH 44135. NASA,LEWIS RES CTR,SVERDRUP TECHNOL INC,CLEVELAND,OH 44135. RP CRUTCHIK, M (reprint author), TEL AVIV UNIV,FAC ENGN,IL-69978 TEL AVIV,ISRAEL. NR 11 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091 SN 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 1995 VL 11 IS 2 BP 373 EP 377 DI 10.2514/3.51435 PG 5 WC Engineering, Aerospace SC Engineering GA QM084 UT WOS:A1995QM08400026 ER PT J AU KIM, YM WANG, TS AF KIM, YM WANG, TS TI NUMERICAL-STUDIES ON DROPLET BREAKUP MODELS SO JOURNAL OF PROPULSION AND POWER LA English DT Note C1 UNIV ALABAMA,DEPT CHEM ENGN,HUNTSVILLE,AL 35899. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,COMPUTAT FLUID DYNAM BRANCH,HUNTSVILLE,AL 35812. RP KIM, YM (reprint author), HANYANG UNIV,DEPT MECH ENGN,SEOUL 133791,SOUTH KOREA. NR 10 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 0748-4658 J9 J PROPUL POWER JI J. Propul. Power PD MAR-APR PY 1995 VL 11 IS 2 BP 389 EP 392 DI 10.2514/3.51439 PG 4 WC Engineering, Aerospace SC Engineering GA QM084 UT WOS:A1995QM08400030 ER PT J AU GANAPOL, BD AF GANAPOL, BD TI RADIATIVE-TRANSFER IN A SEMIINFINITE MEDIUM WITH A SPECULARLY REFLECTING BOUNDARY SO JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER LA English DT Article ID ABSORBING-SCATTERING MEDIUM AB A consistent solution of the radiative transfer equation characterizing photon transport in a semiinfinite medium of refractive index greater than or equal to one is obtained following the method of Sobolev. Fresnel specular reflection, Snell's law and isotropic scattering are assumed. An algorithm is developed and its accuracy is demonstrated. A numerical Laplace transform inversion leads to an efficient evaluation for the interior flux and source function distributions. RP GANAPOL, BD (reprint author), NASA,AMES RES CTR,ECOSYST SCI & TECHNOL BRANCH,MOFFETT FIELD,CA 94035, USA. NR 11 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0022-4073 J9 J QUANT SPECTROSC RA JI J. Quant. Spectrosc. Radiat. Transf. PD MAR PY 1995 VL 53 IS 3 BP 257 EP 267 PG 11 WC Optics; Spectroscopy SC Optics; Spectroscopy GA QW823 UT WOS:A1995QW82300002 ER PT J AU VATSA, VN AF VATSA, VN TI EVALUATION OF A MULTIGRID-BASED NAVIER-STOKES SOLVER FOR AEROTHERMODYNAMIC COMPUTATIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID EQUATIONS; FLOWS AB A multigrid acceleration technique developed for solving the three-dimensional Navier-Stokes equations is used for computing high-Mach-number flows over configurations of practical interest. An explicit multistage Runge-Kutta time-stepping scheme is used as the basic algorithm. Solutions are presented for a spherically blunted cone at Mach 10 and a modified Shuttle orbiter at Mach 6. The computed surface heat-transfer distributions are shown to compare well with the experimental data. Effect of grid refinement on computed heat-transfer distributions is also examined to assess the numerical accuracy of the computed solutions. The rapid convergence rate associated with multigrid schemes in previous applications at transonic speeds is observed at the higher-Mach-number flows investigated here. RP VATSA, VN (reprint author), NASA,LANGLEY RES CTR,AAMB,FMAD,MAIL STOP 128,HAMPTON,VA 23681, USA. NR 22 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1995 VL 32 IS 2 BP 193 EP 199 DI 10.2514/3.26596 PG 7 WC Engineering, Aerospace SC Engineering GA QT160 UT WOS:A1995QT16000001 ER PT J AU CHEN, YK HENLINE, WD TAUBER, ME AF CHEN, YK HENLINE, WD TAUBER, ME TI MARS PATHFINDER TRAJECTORY BASED HEATING AND ABLATION CALCULATIONS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Mars Pathfinder probe will enter the Martian atmosphere at a relative velocity of 7.65 km/s. The 2.65-m-diam vehicle has a blunted, 70-deg-half-angle, conical forebody aerobrake. Axisymmetric time-dependent calculations have been made using Gauss-Seidel implicit aerothermodynamic Navier-Stokes code with thermochemical surface conditions and a program to calculate the charring-material thermal response and ablation for heating analysis and heat-shield material sizing. The two codes are loosely coupled. The flowfield and convective heat-transfer coefficients are computed using the flowfield code with species balance conditions for an ablating surface. The time-dependent in-depth conduction with surface blowing is simulated using the material response code with complete surface energy-balance conditions. This is the first study demonstrating that the computational fluid-dynamics code interfacing with the material response code can be directly applied to the design of thermal protection systems of spacecraft. The heat-shield material is SLA-561V. The solutions, including the flowfield, surface heat fluxes and temperature distributions, pyrolysis-gas blowing rates, in-depth temperature history, and minimum heat-shield thicknesses over the aeroshell forebody, are presented and discussed in detail. The predicted heat-shield mass is about 20 kg. C1 NASA,AMES RES CTR,REACTING FLOW ENVIRONM BRANCH,MOFFETT FIELD,CA 94035. RP CHEN, YK (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MS 234-1,MOFFETT FIELD,CA 94035, USA. NR 19 TC 28 Z9 35 U1 0 U2 2 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1995 VL 32 IS 2 BP 225 EP 230 DI 10.2514/3.26600 PG 6 WC Engineering, Aerospace SC Engineering GA QT160 UT WOS:A1995QT16000005 ER PT J AU FREEMAN, DC TALAY, TA STANLEY, DO LEPSCH, RA WILHITE, AW AF FREEMAN, DC TALAY, TA STANLEY, DO LEPSCH, RA WILHITE, AW TI DESIGN OPTIONS FOR ADVANCED MANNED LAUNCH SYSTEMS SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB Various concepts for advanced manned launch systems are examined for delivery missions to space station and polar orbit. Included are single- and two-stage winged systems with rocket and/or air-breathing propulsion systems. For near-term technologies, two-stage reusable rocket systems are favored over single-stage rocket or two-stage air-breathing/rocket systems. Advanced technologies enable viable single-stage-to-orbit (SSTO) concepts. Although two-stage rocket systems continue to be lighter in dry weight than SSTO vehicles, advantages in simpler operations may make SSTO vehicles more cost-effective over the life cycle. Generally, rocket systems maintain a dry-weight advantage over air-breathing systems at the advanced technology levels, but to a lesser degree than when near-term technologies are used. More detailed understanding of vehicle systems and associated ground and night operations requirements and procedures is essential in determining quantitative discrimination between these latter concepts. C1 NASA,LANGLEY RES CTR,DIV SPACE SYST & CONCEPTS,HAMPTON,VA 23665. NASA,LANGLEY RES CTR,HIGH SPEED RES PROJECT OFF,HAMPTON,VA 23665. RP FREEMAN, DC (reprint author), NASA,LANGLEY RES CTR,TRANSPORTAT OFF,HAMPTON,VA 23665, USA. NR 13 TC 12 Z9 12 U1 0 U2 1 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1995 VL 32 IS 2 BP 241 EP 249 DI 10.2514/3.26602 PG 9 WC Engineering, Aerospace SC Engineering GA QT160 UT WOS:A1995QT16000007 ER PT J AU DESAI, PN TARTABINI, PV AF DESAI, PN TARTABINI, PV TI EFFECT OF DEPARTURE DELAYS ON MANNED MARS MISSION SELECTION SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article ID AEROCAPTURE AB This study determines the effect on the initial mass in low Earth orbit (IMLEO) of delaying departure from Mars and Earth by 5, 15, and 30 days, once a nominal mission to Mars has been selected. Additionally, the use of a deep-space maneuver (DSM) is considered in order to alleviate the IMLEO penalties. Three different classes of missions are analyzed, using chemical and nuclear thermal propulsion systems in the 2000-2025 time frame: opposition, conjunction, and fast-transfer conjunction. The results indicate that Mars and Earth delays can lead to large IMLEO penalties. Opposition and fast-transfer conjunction-class missions have the highest IMLEO penalties, upwards of 432.4 and 1977.3 metric tons (mt), respectively. Conjunction-class missions, on the other hand, tend to be insensitive to Mars and Earth delays, having IMLEO penalties under 103.5 mt. As expected, nuclear thermal propulsion had significantly lower IMLEO penalties than chemical propulsion. The use of a DSM does not significantly reduce the penalties. The results of this study can enable mission designers to incorporate the influence of off-nominal departure conditions of the interplanetary trajectory in the overall conceptual design of a Mars transfer vehicle. RP DESAI, PN (reprint author), NASA,LANGLEY RES CTR,DIV SPACE SYST & CONCEPTS,HAMPTON,VA 23681, USA. NR 15 TC 1 Z9 1 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1995 VL 32 IS 2 BP 250 EP 256 DI 10.2514/3.26603 PG 7 WC Engineering, Aerospace SC Engineering GA QT160 UT WOS:A1995QT16000008 ER PT J AU SCHARTON, TD AF SCHARTON, TD TI VIBRATION-TEST FORCE LIMITS DERIVED FROM FREQUENCY-SHIFT METHOD SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB An improved vibration testing technique has been recently developed and applied to eliminate overtesting caused by the infinite mechanical impedance of the shaker in conventional vibration tests. With the new technique, the acceleration input is notched at the resonance frequencies of the test item in order to limit the shaker force to that predicted for night. Since few night vibratory force data are available, the force limits must be calculated from measurements or analyses of the night mounting structure and test-item mechanical impedances. An improved method of calculating these force limits is derived from evaluating the test-item apparent mass at the coupled-system resonance frequencies. Application of the method to a simple and to a complex coupled oscillator system yields nondimensional results which may be used to calculate limits for future force-limited vibration tests. For example, using the simple system results with Q = 50 and equal impedances of the night mounting structure and test item, the input acceleration amplitude will be notched by a factor of 31.25 relative to a conventional test. RP SCHARTON, TD (reprint author), CALTECH,JET PROP LAB,MAIL STOP 301-456,4800 OAK GROVE DR,PASADENA,CA 91109, USA. NR 17 TC 7 Z9 8 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1995 VL 32 IS 2 BP 312 EP 316 DI 10.2514/3.26611 PG 5 WC Engineering, Aerospace SC Engineering GA QT160 UT WOS:A1995QT16000016 ER PT J AU POLITES, ME SHARKEY, JP NURRE, GS CALHOUN, PC LIGHTSEY, WD AF POLITES, ME SHARKEY, JP NURRE, GS CALHOUN, PC LIGHTSEY, WD TI ADVANCED X-RAY ASTROPHYSICS FACILITY-SPECTROMETRY SPACECRAFT POINTING CONTROL-SYSTEM - CONCEPTUAL DESIGN SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Article AB The Advanced X-Ray Astrophysics Facility-Spectrometry is an orbiting astronomical observatory using grazing-incidence optics to focus x-ray images on a liquid-helium-cooled imaging x-ray spectrometer (XRS). It will be launched on a Delta-II launch vehicle into a 650-km, circular, sun-synchronous orbit and will be operated as a national observatory for an expected period of 5 years. This paper describes the conceptual design of the pointing control system (PCS), whose function is to acquire x-ray targets on the XRS detector and maintain a pointing stability of 5.5'' (rms) per axis over any 10-min period that excludes a day-night or night-day terminator crossing. The proposed PCS design attempts to use the best features of previous PCS designs, but has several new features not found on other spacecraft. Hence, it can serve as a good starting point and reference for PCS designers of future spacecraft. Error budgets and preliminary simulation results show the soundness of the design approach. RP POLITES, ME (reprint author), NASA, GEORGE C MARSHALL SPACE FLIGHT CTR, PRECIS POINTING SYST BRANCH, HUNTSVILLE, AL 35812 USA. NR 10 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1995 VL 32 IS 2 BP 344 EP 352 DI 10.2514/3.26616 PG 9 WC Engineering, Aerospace SC Engineering GA QT160 UT WOS:A1995QT16000021 ER PT J AU WADAWADIGI, G TANNEHILL, JC LAWRENCE, SL EDWARDS, TA AF WADAWADIGI, G TANNEHILL, JC LAWRENCE, SL EDWARDS, TA TI INTEGRATED AERODYNAMIC AND PROPULSIVE FLOWFIELDS OF A GENERIC HYPERSONIC SPACE PLANE SO JOURNAL OF SPACECRAFT AND ROCKETS LA English DT Note ID NAVIER-STOKES CODE C1 IOWA STATE UNIV SCI & TECHNOL,DEPT AEROSP ENGN & ENGN MECH,AMES,IA 50011. NASA,AMES RES CTR,COMPUTAT AEROSCI BRANCH,MOFFETT FIELD,CA 94035. NR 14 TC 0 Z9 0 U1 0 U2 0 PU AMER INST AERONAUT ASTRONAUT PI RESTON PA 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA SN 0022-4650 J9 J SPACECRAFT ROCKETS JI J. Spacecr. Rockets PD MAR-APR PY 1995 VL 32 IS 2 BP 380 EP 382 DI 10.2514/3.26624 PG 3 WC Engineering, Aerospace SC Engineering GA QT160 UT WOS:A1995QT16000029 ER PT J AU LEE, KN MILLER, RA JACOBSON, NS AF LEE, KN MILLER, RA JACOBSON, NS TI NEW-GENERATION OF PLASMA-SPRAYED MULLITE COATINGS ON SILICON-CARBIDE SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID ENVIRONMENTS; CORROSION; CERAMICS AB Mullite is promising as a protective coating for silicon-based ceramics in aggressive high-temperature environments. Conventionally plasma-sprayed mullite on SiC tends to crack and debond on thermal cycling. It is shown that this behavior is due to the presence of amorphous mullite in the conventionally sprayed mullite. Heating the SiC substrate during the plasma spraying eliminated the amorphous phase and produced coatings with dramatically improved properties. The new coating exhibits excellent adherence and crack resistance under thermal cycling between room temperature and 1000-1400 degrees C. Preliminary tests showed good resistance to Na2CO3-induced hot corrosion. RP LEE, KN (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Jacobson, Nathan/A-9411-2009 NR 23 TC 124 Z9 137 U1 5 U2 37 PU AMER CERAMIC SOC 735 CERAMIC PLACE PI WESTERVILLE PA PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD MAR PY 1995 VL 78 IS 3 BP 705 EP 710 DI 10.1111/j.1151-2916.1995.tb08236.x PG 6 WC Materials Science, Ceramics SC Materials Science GA QM996 UT WOS:A1995QM99600030 ER PT J AU LEE, KN JACOBSON, NS AF LEE, KN JACOBSON, NS TI CHEMICAL-STABILITY OF THE FIBER COATING MATRIX INTERFACE IN SILICON-BASED CERAMIC-MATRIX COMPOSITES SO JOURNAL OF THE AMERICAN CERAMIC SOCIETY LA English DT Article ID FAILURE AB Carbon and boron nitride are used as fiber coatings in silicon-based composites. In order to assess the long-term stability of these materials, reactions of carbon/Si3N4 and BN/SiC were studied at high temperatures with Knudsen effusion, coupon tests, and by microstructural examination. In the carbon/Si3N4 system, carbon reacted with Si3N4 to form gaseous N-2 and SiC. The formation of SiC limited further reaction by physically separating the carbon and Si3N4. Consequently, the development of high p(N-2) at the interface, predicted from thermochemical calculations, did not occur, thus limiting the potential deleterious effects of the reaction on the composite. Strong indications of a reaction between BN and SiC were shown by TEM and SIMS analysis of the BN/SiC interface. In long-term exposures, this reaction can lead to a depletion of a BN coating and/or an unfavorable change of the interfacial properties, limiting the beneficial effects of the coating. RP LEE, KN (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. RI Jacobson, Nathan/A-9411-2009 NR 14 TC 9 Z9 9 U1 0 U2 2 PU AMER CERAMIC SOC 735 CERAMIC PLACE PI WESTERVILLE PA PO BOX 6136, WESTERVILLE, OH 43081-6136 SN 0002-7820 J9 J AM CERAM SOC JI J. Am. Ceram. Soc. PD MAR PY 1995 VL 78 IS 3 BP 711 EP 715 DI 10.1111/j.1151-2916.1995.tb08237.x PG 5 WC Materials Science, Ceramics SC Materials Science GA QM996 UT WOS:A1995QM99600031 ER PT J AU HINES, CO AF HINES, CO TI MODULATED MOUNTAIN WAVES SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Note ID ARECIBO AB The theory of mountain waves is usually discussed for the case of a steady background wind. Here, the consequences of a superimposed diurnal (or other periodic) background wind variation are considered in outline. They are found to be sufficiently complicated as to warrant avoidance in detailed case studies. They include, however, the production of freely propagating waves and may be of interest on that account for other purposes. C1 NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES BRANCH,GREENBELT,MD 20771. NR 4 TC 9 Z9 9 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 1 PY 1995 VL 52 IS 5 BP 602 EP 606 DI 10.1175/1520-0469(1995)052<0602:MMW>2.0.CO;2 PG 5 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QN298 UT WOS:A1995QN29800007 ER PT J AU HINES, CO AF HINES, CO TI OBSERVATIONS OF LOW-FREQUENCY INERTIA GRAVITY-WAVES IN THE LOWER STRATOSPHERE OVER ARECIBO - COMMENT SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Note C1 NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES BRANCH,GREENBELT,MD 20771. NR 4 TC 7 Z9 7 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 1 PY 1995 VL 52 IS 5 BP 607 EP 610 DI 10.1175/1520-0469(1995)052<0607:COOLFI>2.0.CO;2 PG 4 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QN298 UT WOS:A1995QN29800008 ER PT J AU HINES, CO AF HINES, CO TI MODULATED MOUNTAIN WAVES - REPLY SO JOURNAL OF THE ATMOSPHERIC SCIENCES LA English DT Note C1 NASA,GODDARD SPACE FLIGHT CTR,PLANETARY ATMOSPHERES BRANCH,GREENBELT,MD 20771. NR 4 TC 1 Z9 1 U1 0 U2 0 PU AMER METEOROLOGICAL SOC PI BOSTON PA 45 BEACON ST, BOSTON, MA 02108-3693 SN 0022-4928 J9 J ATMOS SCI JI J. Atmos. Sci. PD MAR 1 PY 1995 VL 52 IS 5 BP 613 EP 613 DI 10.1175/1520-0469(1995)052<0613:R>2.0.CO;2 PG 1 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QN298 UT WOS:A1995QN29800010 ER PT J AU OGBUJI, LUJT OPILA, EJ AF OGBUJI, LUJT OPILA, EJ TI A COMPARISON OF THE OXIDATION-KINETICS OF SIC AND SI3N4 SO JOURNAL OF THE ELECTROCHEMICAL SOCIETY LA English DT Article ID SINGLE-CRYSTAL SILICON; PASSIVE OXIDATION; CARBIDE; NITRIDE; OXYNITRIDE; OXYGEN AB There is lingering disagreement over the relative oxidation kinetics of SiC and Si3N4 in the regime of passive oxidation. Various oxidation enthalpies have been reported for these materials, in some cases with suggestions of an increase at higher temperatures. The result is uncertainty over the respective diffusion mechanisms that limit oxidation rates in these materials. It is suspected that this confusion mag be due, in large part, to the effects of impurities from the oxidation environment. Accordingly, this study was aimed at clarifying some of the issues by undertaking the simultaneous oxidation of CVD SiC and Si3N4 within a furnace tube of fused silica known to be very pure. We discuss the results obtained in the interval 1200 to 1500 degrees C, and their implications on the respective rate-limiting mechanisms. C1 CLEVELAND STATE UNIV,DEPT CHEM ENGN,CLEVELAND,OH 44115. RP OGBUJI, LUJT (reprint author), NASA,LEWIS RES CTR,NYMA,CLEVELAND,OH 44135, USA. NR 24 TC 128 Z9 132 U1 2 U2 26 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 1995 VL 142 IS 3 BP 925 EP 930 DI 10.1149/1.2048559 PG 6 WC Electrochemistry; Materials Science, Coatings & Films SC Electrochemistry; Materials Science GA QL585 UT WOS:A1995QL58500049 ER PT J AU KELLMAN, PJ KAISER, MK AF KELLMAN, PJ KAISER, MK TI EXTRACTING OBJECT MOTION DURING OBSERVER MOTION - COMBINING CONSTRAINTS FROM OPTIC FLOW AND BINOCULAR DISPARITY SO JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION LA English DT Note AB Detection of object motion by moving observers and perception of velocity by stationary or moving observers ordinarily require information about object distance. It might be expected that object motion could be obtained without distance by use of a combination of optic flow and binocular disparity information. We describe how object motion could, in principle, be derived this way. The analysis also permits recovery of target distance. Finally, information about the observer's motion may be obtained in a similar fashion, assuming the existence of two stationary environmental points at an unknown distance. Although studies of human observers have not been completed, it appears that these informational variables are available under conditions in which observers perform well at detecting motion and stability. In particular, the information may help to explain why a visible surface in near space facilitates accurate perception. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP KELLMAN, PJ (reprint author), UNIV CALIF LOS ANGELES,DEPT PSYCHOL,FRANZ HALL,405 HILGARD AVE,LOS ANGELES,CA 90024, USA. NR 6 TC 8 Z9 8 U1 0 U2 1 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0740-3232 J9 J OPT SOC AM A JI J. Opt. Soc. Am. A-Opt. Image Sci. Vis. PD MAR PY 1995 VL 12 IS 3 BP 623 EP 625 DI 10.1364/JOSAA.12.000623 PG 3 WC Optics SC Optics GA QJ127 UT WOS:A1995QJ12700020 PM 7891215 ER PT J AU WONG, SS HE, G NIKZAD, S AHN, CC ATWATER, HA AF WONG, SS HE, G NIKZAD, S AHN, CC ATWATER, HA TI LOCAL ORDER MEASUREMENT IN SNGE ALLOYS AND MONOLAYER SN FILMS ON SI WITH REFLECTION ELECTRON-ENERGY-LOSS SPECTROMETRY SO JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A-VACUUM SURFACES AND FILMS LA English DT Article ID FINE-STRUCTURE SPECTROSCOPY; MOLECULAR-BEAM EPITAXY; GROWTH; SI(111) C1 CALTECH,JET PROP LAB,MICRODEVICES LAB,PASADENA,CA 91109. RP WONG, SS (reprint author), CALTECH,THOMAS J WATSON LAB APPL PHYS,PASADENA,CA 91125, USA. NR 14 TC 5 Z9 5 U1 0 U2 6 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0734-2101 J9 J VAC SCI TECHNOL A JI J. Vac. Sci. Technol. A-Vac. Surf. Films PD MAR-APR PY 1995 VL 13 IS 2 BP 216 EP 220 DI 10.1116/1.579401 PG 5 WC Materials Science, Coatings & Films; Physics, Applied SC Materials Science; Physics GA QM440 UT WOS:A1995QM44000009 ER PT J AU VODACEK, A HOGE, FE SWIFT, RN YUNGEL, JK PELTZER, ET BLOUGH, NV AF VODACEK, A HOGE, FE SWIFT, RN YUNGEL, JK PELTZER, ET BLOUGH, NV TI THE USE OF IN SITU AND AIRBORNE FLUORESCENCE MEASUREMENTS TO DETERMINE UV ABSORPTION COEFFICIENTS AND DOC CONCENTRATIONS IN SURFACE WATERS SO LIMNOLOGY AND OCEANOGRAPHY LA English DT Note ID DISSOLVED ORGANIC-CARBON; OPTICAL ATTENUATION; NATURAL-WATERS; PHOTODEGRADATION; CHLOROPHYLL; MATTER; SEA AB We compared the fluorescence (lambda(ex) = 355 nm, lambda(em) = 450 nm) of chromophore-containing dissolved organic matter (CDOM) determined in the laboratory to that determined with a shipboard fluorometer and an airborne laser fluorosensor off the U.S. mid-Atlantic coast. Fluorescence was highly correlated with CDOM absorption at the excitation wavelength despite the presence of multiple sources of CDOM and a changing contribution of CDOM to the total dissolved organic C (DOC) pool, both in surface waters and down the water column. The mean quantum yield (0.8+/-0.1%) fell within the narrow range of yields previously determined for U.S. east coast and south Florida waters. These results show that CDOM absorption can be reliably determined from in situ or airborne fluorescence over wide areas of the ocean and that it may be possible to estimate DOC concentration from fluorescence or absorption measurements. C1 NASA, GODDARD SPACE FLIGHT CTR, WALLOPS FLIGHT FACIL, OBSERVAT SCI BRANCH, WALLOPS ISL, VA 23337 USA. RI Blough, Neil/B-7727-2009; Vodacek, Anthony/F-1585-2011; OI Vodacek, Anthony/0000-0001-9196-0928; Peltzer, Edward/0000-0003-2821-3553 NR 24 TC 107 Z9 121 U1 0 U2 14 PU AMER SOC LIMNOLOGY OCEANOGRAPHY PI WACO PA 5400 BOSQUE BLVD, STE 680, WACO, TX 76710-4446 USA SN 0024-3590 J9 LIMNOL OCEANOGR JI Limnol. Oceanogr. PD MAR PY 1995 VL 40 IS 2 BP 411 EP 415 PG 5 WC Limnology; Oceanography SC Marine & Freshwater Biology; Oceanography GA QZ608 UT WOS:A1995QZ60800019 ER PT J AU FUSARO, RL AF FUSARO, RL TI LUBRICATION OF SPACE SYSTEMS SO LUBRICATION ENGINEERING LA English DT Article ID MOS2; SURFACES; FILMS AB NASA has many high technology programs planned for the future: such as the space station, ''Mission to Planet Earth'' (a series of Earth observing satellites), space telescopes, and planetary orbiters and landers. These missions will involve advanced mechanical moving components that will need wear protection and lubrication. The tribology practices used in space today are primarily based upon a technology more than 20 years old. The question is, is this technology base good enough to meet the needs of these future long-duration NASA missions? This paper examines NASA's future space missions, how mechanisms are currently lubricated, some of the mechanism and tribology challenges that may be encountered in future missions, and some potential solutions to these future challenges. RP FUSARO, RL (reprint author), NASA,LEWIS RES CTR,DIV STRUCTURES,CLEVELAND,OH 44135, USA. NR 41 TC 24 Z9 24 U1 1 U2 3 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 MAR PY 1995 VL 51 IS 3 BP 182 EP 194 PG 13 WC Engineering, Mechanical SC Engineering GA QM829 UT WOS:A1995QM82900001 ER PT J AU PINDERA, MJ ABOUDI, J ARNOLD, SM AF PINDERA, MJ ABOUDI, J ARNOLD, SM TI LIMITATIONS OF THE UNCOUPLED, RVE-BASED MICROMECHANICAL APPROACH IN THE ANALYSIS OF FUNCTIONALLY GRADED COMPOSITES SO MECHANICS OF MATERIALS LA English DT Article DE FUNCTIONALLY GRADED COMPOSITES; RVE-BASED MICROMECHANICS; COUPLED MICROMECHANICS; HOMOGENIZATION LIMITATION AB A new class of materials, called functionally graded composites, has recently evolved in which the microstructure is tailored to meet specific applications. This is accomplished by distributing the reinforcement phase in a nonuniform manner, resulting in statistically inhomogeneous composites. The standard micromechanical approach used to analyse the response of this class of materials is to decouple the local and global effects by assuming the existence of a representative volume element at every point within the composite. Recently, a new micromechanical theory, which couples the local and global effects, has been developed and applied to functionally graded composites. Herein, this theory is used to assess the limits of applicability of the standard micromechanical approach in predicting local stresses in the fiber and matrix phases of functionally graded composites subjected to a thermal gradient. It is shown that the simplified uncoupled approach is inaccurate when the dimension of the reinforcement phase is large relative to the dimension of the composite. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP PINDERA, MJ (reprint author), UNIV VIRGINIA,CIVIL ENGN & APPL MECH,CHARLOTTESVILLE,VA 22901, USA. NR 12 TC 39 Z9 41 U1 1 U2 4 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0167-6636 J9 MECH MATER JI Mech. Mater. PD MAR PY 1995 VL 20 IS 1 BP 77 EP 94 DI 10.1016/0167-6636(94)00052-2 PG 18 WC Materials Science, Multidisciplinary; Mechanics SC Materials Science; Mechanics GA QL641 UT WOS:A1995QL64100005 ER PT J AU BOWMAN, RR MISRA, AK ARNOLD, SM AF BOWMAN, RR MISRA, AK ARNOLD, SM TI PROCESSING AND MECHANICAL-PROPERTIES OF AL2O3 FIBER-REINFORCED NIAL COMPOSITES SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE LA English DT Article ID FRACTURE-TOUGHNESS; MATRIX COMPOSITES; TENSILE-STRENGTH; WEIBULL MODULUS; SHEAR-STRENGTH; ALUMINUM-OXIDE; TEMPERATURE; BEHAVIOR; DEFORMATION AB The mechanical properties of NiAl-matrix composites reinforced with 125-mu m diameter single-crystal Al2O3 (sapphire) fibers have been examined over the temperature range of 300 to 1200 K. Composites were fabricated with either a strong or weak fiber-matrix interfacial bond strength. During fabrication, a fiber-matrix interaction occurred such that fibers extracted from the NiAl matrix were fragmented and significantly weaker than the as-received fibers. Tensile results of the weakly bonded composite demonstrated that the composite stiffness was greater than the monolithic at both 300 and 1200 K in spite of the weak bond. Room-temperature strengths of the composite were greater than that of the monolithic but below rule-of-mixture predictions (even when the degraded fiber strengths were accounted for). At 1200 K, the ultimate strength of the composite was inferior to that of the monolithic primarily because of the poor fiber properties. No tensile data was obtained on the strongly bonded material because of the occurrence of matrix cracking during fabrication. Primarily because of the fiber strength loss, sapphire-NiAl composite mechanical properties are inferior to conventional high-temperature materials such as superalloys and are currently unsuitable for structural applications. C1 NYMA INC,LERC GRP,BROOKPARK,OH 44142. RP BOWMAN, RR (reprint author), NASA,LEWIS RES CTR,CLEVELAND,OH 44135, USA. NR 55 TC 55 Z9 58 U1 0 U2 4 PU MINERALS METALS MATERIALS SOC PI WARRENDALE PA 420 COMMONWEALTH DR, WARRENDALE, PA 15086 SN 1073-5623 J9 METALL MATER TRANS A JI Metall. Mater. Trans. A-Phys. Metall. Mater. Sci. PD MAR PY 1995 VL 26 IS 3 BP 615 EP 628 DI 10.1007/BF02663910 PG 14 WC Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Materials Science; Metallurgy & Metallurgical Engineering GA QH155 UT WOS:A1995QH15500010 ER PT J AU BASU, A MCKAY, DS AF BASU, A MCKAY, DS TI LUNAR SOIL EVOLUTION PROCESSES AND APOLLO-16 CORE-60013/60014 SO METEORITICS LA English DT Article ID REGOLITHS AB Soils of the 62-cm deep Apollo 16 double drive tube 60013/14 are mature at the top and submature at the bottom. Modal analyses of 5529 grains from the 90-150 mu m and the 500-1000 mu m fractions from 12 levels of the core show that, in general, agglutinate abundance increases somewhat monotonically to the top and mimics the I-s/FeO profile. There is a general decrease in the modal abundance of monomineralic fragments towards the top, suggesting that agglutinates were formed in part at the expense of monomineralic grains, especially feldspars, which are by far the most abundant mineral in these soils. In detail, the top 27 cm of the core differs from the bottom 21 cm, and the middle 14 cm is intermediate in its properties. In the upper segment, variations in the abundances of feldspars correspond with those of feldspathic fragmental breccias and cataclastic anorthosites; in the bottom segment, a similar but weak correspondence between feldspars and crystalline matrix breccias is observed. Mixing of the comminuted products of these three rock types likely produced the bulk of the core material. Many single feldspars in all size fractions are remarkably fresh, show no damage from shock, and are similar in appearance to the large feldspars in anorthosites and feldspathic fragmental breccias, which we consider to be the primary sources of single feldspars in this core. Major (Na, Al, Si, K, Ca) and minor (Fe, Ba) element analyses of 198 single feldspar grains indicate the presence of only one population of feldspars, which is consistent with our interpretation of feldspar provenance. Classification of 890 monomineralic feldspar, olivine, pyroxene, and glass spherules on the basis of the presence or absence of thin brownish coating-related to reworking at the surface-shows that coated grains are much more abundant in the top segment than in the bottom segment. A comparison with the mixing and maturation model (McKay et al., 1977) of soils in the core 60009/10, some 60 m away from 60013/14, shows that mixtures of an immature, nearly pure plagioclase soil (dominant in 60009/10) and another immature, crystalline breccia-rich soil (dominant in 60013/14) may have matured through in situ reworking to produce the soils under investigation. We conclude that the soils in this core are products of mixing along soil evolution Path 2 of McKay et al. (1974). Superimposed on that soil column is the reworking of the upper part, which has evolved more recently along Path 1. This core thus represents a consanguineous column of the lunar regolith with an upper reworked segment. C1 NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058. RP BASU, A (reprint author), INDIANA UNIV,DEPT GEOL SCI,BLOOMINGTON,IN 47405, USA. FU NINDS NIH HHS [NSG-9077] NR 37 TC 3 Z9 3 U1 0 U2 1 PU METEORITICAL SOC PI FAYETTEVILLE PA DEPT CHEMISTRY/BIOCHEMISTRY, UNIV ARKANSAS, FAYETTEVILLE, AR 72701 SN 0026-1114 J9 METEORITICS JI Meteoritics PD MAR PY 1995 VL 30 IS 2 BP 162 EP 168 PG 7 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QN084 UT WOS:A1995QN08400003 PM 11539134 ER PT J AU WU, TK AF WU, TK TI SIMULATION OF ANTENNA RADIATION-PATTERN SO MICROWAVE AND OPTICAL TECHNOLOGY LETTERS LA English DT Article DE ANTENNAS; RADIATION PATTERN; COMPUTER SIMULATION AB Adequately modeling the radiation pattern of a high-performance antenna system usually requires the expensive development of complicated electromagnetic software or the storage of an extremely large number of measured data. An alternative and efficient simulation technique is described in this article using a spherical wave expansion model, which requires the storage of a relatively small number of coefficients to define the function for the antenna's radiation pattern. (C) 1995 John Wiley & Sons, Inc. RP WU, TK (reprint author), JET PROP LAB,PASADENA,CA 91109, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU JOHN WILEY & SONS INC PI NEW YORK PA 605 THIRD AVE, NEW YORK, NY 10158-0012 SN 0895-2477 J9 MICROW OPT TECHN LET JI Microw. Opt. Technol. Lett. PD MAR PY 1995 VL 8 IS 4 BP 204 EP 206 DI 10.1002/mop.4650080410 PG 3 WC Engineering, Electrical & Electronic; Optics SC Engineering; Optics GA QH660 UT WOS:A1995QH66000009 ER PT J AU LEE, TJ RACINE, SC AF LEE, TJ RACINE, SC TI A COUPLED-CLUSTER STUDY OF THE MOLECULAR-STRUCTURE, VIBRATIONAL-SPECTRUM AND RELATIVE ENERGIES OF THE XCN AND XNC (X=F, CL) ISOMERS SO MOLECULAR PHYSICS LA English DT Article ID ABINITIO CALCULATIONS; CHLORINE NITRATE; FORCE-FIELDS; AB-INITIO; ENERGETICS; CHEMISTRY; STATES; CL2O2; FCN; HCN AB The XCN and XNC (X = F, Cl) isomers have been investigated using the CCSD and CCSD(T) methods in conjunction with a TZ2P basis set. Equilibrium geometries, dipole moments, harmonic frequencies, infrared intensities and relative energies have been evaluated. The CCSD(T) geometries and vibrational frequencies for the XCN isomers are in good agreement with the available experimental data. The CCSD(T) results for FCN and FNC are in good agreement with CEPA calculations of Botschwina et al., with the exception of the energy difference, which the CEPA method underestimates by about 1.2 kcal mol(-1). FCN and ClCN are shown to be lower in energy than the FNC and ClNC isomers by 69.5 +/- 1.0 kcal mol(-1) and 42.7 +/- 1.0 kcal mol(-1) (0 K), respectively. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Lee, Timothy/K-2838-2012 NR 32 TC 14 Z9 14 U1 0 U2 2 PU TAYLOR & FRANCIS LTD PI ABINGDON PA 4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLAND SN 0026-8976 J9 MOL PHYS JI Mol. Phys. PD MAR PY 1995 VL 84 IS 4 BP 717 EP 725 DI 10.1080/00268979500100491 PG 9 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QQ267 UT WOS:A1995QQ26700008 ER PT J AU NANDRA, K TURNER, TJ GEORGE, IM FABIAN, AC SHRADER, C SUN, WH AF NANDRA, K TURNER, TJ GEORGE, IM FABIAN, AC SHRADER, C SUN, WH TI SOFT-X-RAY AND ULTRAVIOLET OBSERVATIONS OF MRK-841 - IMPLICATIONS FOR THE BLUE BUMP SO MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY LA English DT Article DE GALAXIES, ACTIVE; GALAXIES, INDIVIDUAL, MRK 841; GALAXIES, NUCLEI GALAXIES, SEYFERT; X-RAYS, GALAXIES ID ACTIVE GALACTIC NUCLEI; ACCRETION DISKS; SEYFERT-GALAXIES; COLD MATTER; QUASARS; NGC-5548; SPECTRA; VARIABILITY; CONTINUUM; EMISSION AB We present an analysis of an extended ROSAT observation of the Seyfert galaxy Mrk 841. The source is clearly variable on short time-scales with distinctive changes in the hardness ratio, indicating that more than one spectral component is present in the PSPC band. Spectral modelling of the soft X-ray data confirms this complex picture. The data show that the continuum is particularly steep in the soft band (Gamma=2.4). We find that the soft X-ray spectrum is best fitted by models in which the primary power law is modified either by absorption by highly ionized material in the line of sight, or by an additional emission component which contributes to the lowest PSPC channels. Simultaneous spectral fitting of the PSPC data and the UV continuum data, which were obtained contemporaneously with IUE, show that the best-fitting power law in the soft X-ray extrapolates well into the UV and carries the bulk of the source power. We have been unable to find a satisfactory fit to the UV/soft X-ray emission with standard accretion disc models. One possibility is that the disc spectrum is modified substantially by Comptonization in a corona above the disc. Future variability data should allow us to test this model. C1 NASA,GODDARD SPACE FLIGHT CTR,HIGH ENERGY ASTROPHYS LAB,GREENBELT,MD 20771. NASA,GODDARD SPACE FLIGHT CTR,CTR SCI SUPPORT,CGRO,GREENBELT,MD 20771. NATL CENT UNIV,DEPT PHYS,CHUNGLI 32054,TAIWAN. NATL CENT UNIV,INST ASTRON,CHUNGLI 32054,TAIWAN. RP NANDRA, K (reprint author), UNIV CAMBRIDGE,INST ASTRON,MADINGLEY RD,CAMBRIDGE CB3 0HA,ENGLAND. NR 34 TC 17 Z9 17 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 1995 VL 273 IS 1 BP 85 EP 92 PG 8 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QK659 UT WOS:A1995QK65900013 ER PT J AU GYUK, G TURNER, MS AF GYUK, G TURNER, MS TI MEV TAU-NEUTRINO - ASTROPHYSICAL AND COSMOLOGICAL CONSTRAINTS AND MISCHIEF SO NUCLEAR PHYSICS B LA English DT Article; Proceedings Paper CT 3rd Workshop on Tau Lepton Physics CY SEP 19-22, 1994 CL MONTREUX, SWITZERLAND ID COLD DARK-MATTER; LARGE-SCALE STRUCTURE; PRIMORDIAL NUCLEOSYNTHESIS; RADIATIVE DECAY; DIRAC NEUTRINOS; SN-1987A; UNIVERSE; LIMITS; MASS; HOT AB Terrestrial and ''Heavenly'' experiments severely constrain the mass and lifetime of an MeV tau neutrino. Irrespective of decay mode, for tau(nu), greater than or similar to 300 sec the mass must be less than 0.4 MeV (Majorana), 15 keV (Dirac). If the dominant decay mode includes electromagnetic daughter products, the mass must be less than 0.4 MeV (Majorana or Dirac) provided tau(nu) greater than or similar to 2.5 x 10(-12) sec, 15 keV (Dirac) provided tau(nu) greater than or similar to 10(-6) sec(m(nu)/MeV). A tau neutrino of mass between 1 MeV and 30 MeV can have a host of interesting astrophysical and cosmological consequences: relaxing the big-bang nucleosynthesis bound to the baryon density and the number of neutrino species, allowing big-bang nucleosynthesis to accommodate a low (less than 22%) He-4 mass fraction or high (greater than 10(-4)) deuterium abundance, improving significantly the agreement between the cold dark matter theory of structure formation and observations, and helping to explain how type II supernovae explode. Exploring the MeV mass range not only probes fundamental particle physics, but also interesting astrophysical and cosmological scenarios. C1 FERMILAB NATL ACCELERATOR LAB, NASA, FERMILAB ASTROPHYS CTR, BATAVIA, IL 60510 USA. UNIV CHICAGO, ENRICO FERMI INST, DEPT ASTRON & ASTROPHYS, CHICAGO, IL 60637 USA. UNIV CHICAGO, DEPT PHYS, CHICAGO, IL 60637 USA. NR 58 TC 4 Z9 4 U1 0 U2 0 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0550-3213 EI 1873-1562 J9 NUCL PHYS B JI Nucl. Phys. B PD MAR PY 1995 SU 40 BP 557 EP 567 DI 10.1016/0920-5632(95)00179-D PG 11 WC Physics, Particles & Fields SC Physics GA QP390 UT WOS:A1995QP39000055 ER PT J AU CIRCELLI, BR ROGERS, SE AF CIRCELLI, BR ROGERS, SE TI AN UNCOUPLED ALGORITHM FOR CALCULATING STEADY-STATE LAMINAR HEAT-TRANSFER IN 3-DIMENSIONAL INCOMPRESSIBLE-FLOW SO NUMERICAL HEAT TRANSFER PART B-FUNDAMENTALS LA English DT Article ID NAVIER-STOKES EQUATIONS; SCHEMES AB An uncoupled algorithm for the solution of the steady-state thermal energy equation in three-dimensional generalized curvilinear coordinates for an incompressible flow is described. The algorithm uses a higher-order flux-difference splitting technique for the convective terms and a second-order central difference scheme for the conductive terms. The equation is solved using a line-relaxation technique that allows the use of very large time steps, leading to rapid convergence. Preliminary results that demonstrate the code's predictive capability are presented. The results agree well with test cases for which analytical solutions can be obtained and with classical boundary-layer theory. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. RP CIRCELLI, BR (reprint author), MICROCRAFT TECHNOL,ARNOLD ENGN DEV CTR OPERAT,740 4TH ST,ARNOLD AFB,TN 37389, USA. NR 20 TC 1 Z9 1 U1 0 U2 0 PU HEMISPHERE PUBL CORP PI BRISTOL PA 1900 FROST ROAD, SUITE 101, BRISTOL, PA 19007-1598 SN 1040-7790 J9 NUMER HEAT TR B-FUND JI Numer Heat Tranf. B-Fundam. PD MAR PY 1995 VL 27 IS 2 BP 237 EP 253 DI 10.1080/10407799508914955 PG 17 WC Thermodynamics; Mechanics SC Thermodynamics; Mechanics GA QQ066 UT WOS:A1995QQ06600006 ER PT J AU DEMMEL, JW HIGHAM, NJ SCHREIBER, RS AF DEMMEL, JW HIGHAM, NJ SCHREIBER, RS TI STABILITY OF BLOCK LU FACTORIZATION SO NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS LA English DT Article DE BLOCK ALGORITHM; LAPACK; LEVEL 3 BLAS; ITERATIVE REFINEMENT; LU FACTORIZATION; BACKWARD ERROR ANALYSIS; BLOCK DIAGONAL DOMINANCE ID LINEAR ALGEBRA SUBPROGRAMS; MATRICES; ALGORITHMS; COMPUTATIONS; EQUATIONS; SYSTEMS; SET AB Many of the currently popular 'block algorithms' are scalar algorithms in which the operations have been grouped and reordered into matrix operations. One genuine block algorithm in practical use is block LU factorization, and this has recently been shown by Demmel and Higham to be unstable in general. It is shown here that block LU factorization is stable if A is block diagonally dominant by columns. Moreover, for a general matrix the level of instability in block LU factorization can be bounded in terms of the condition number kappa(A) and the growth factor for Gaussian elimination without pivoting. A consequence is that block LU factorization is stable for a matrix A that is symmetric positive definite or point diagonally dominant by rows or columns as long as A is well-conditioned. C1 UNIV CALIF BERKELEY,DEPT MATH,BERKELEY,CA 94720. UNIV MANCHESTER,DEPT MATH,MANCHESTER M13 9PL,LANCS,ENGLAND. NASA,AMES RES CTR,RIACS,MOFFETT FIELD,CA 94035. RP DEMMEL, JW (reprint author), UNIV CALIF BERKELEY,DIV COMP SCI,BERKELEY,CA 94720, USA. RI Higham, Nicholas/A-2315-2009 OI Higham, Nicholas/0000-0001-5956-4976 NR 30 TC 37 Z9 37 U1 0 U2 1 PU JOHN WILEY & SONS LTD PI W SUSSEX PA BAFFINS LANE CHICHESTER, W SUSSEX, ENGLAND PO19 1UD SN 1070-5325 J9 NUMER LINEAR ALGEBR JI Numer. Linear Algebr. Appl. PD MAR-APR PY 1995 VL 2 IS 2 BP 173 EP 190 DI 10.1002/nla.1680020208 PG 18 WC Mathematics, Applied; Mathematics SC Mathematics GA RB375 UT WOS:A1995RB37500007 ER PT J AU HUCK, FO FALES, CL JOBSON, DJ RAHMAN, ZU AF HUCK, FO FALES, CL JOBSON, DJ RAHMAN, ZU TI ELECTROOPTICAL DESIGN FOR EFFICIENT VISUAL COMMUNICATION SO OPTICAL ENGINEERING LA English DT Article DE ELECTROOPTICAL DESIGN; INFORMATION; ENTROPY; DYNAMIC-RANGE COMPRESSION; IMAGE CODING; IMAGE RESTORATION ID GANGLION-CELLS; MACAQUE MONKEY; CORTEX; IMPROVEMENT; SYSTEM; COLOR AB Visual communication, in the form of telephotography and television, for example, can be regarded as efficient only if the amount of information that it conveys about the scene to the observer approaches the maximum possible and the associated cost approaches the minimum possible. Elsewhere we have addressed the problem of assessing the end-to-end performance of visual communication systems in terms of their efficiency in this sense by integrating the critical limiting factors that constrain image gathering into classical communication theory. We use this approach to assess the electro-optical design of image-gathering devices as a function of the f number and apodization of the objective lens and the aperture size and sampling geometry of the photodetection mechanism. Results show that an image-gathering device that is designed to optimize information capacity performs similarly to the human eye. For both, the performance approaches the maximum possible, in terms of the efficiency with which the acquired information can be transmitted as decorrelated data, and the fidelity, sharpness, and clarity with which fine detail can be restored. C1 SCI & TECHNOL CORP, HAMPTON, VA 23666 USA. RP NASA, LANGLEY RES CTR, HAMPTON, VA 23681 USA. NR 65 TC 7 Z9 7 U1 0 U2 0 PU SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS PI BELLINGHAM PA 1000 20TH ST, PO BOX 10, BELLINGHAM, WA 98225 USA SN 0091-3286 EI 1560-2303 J9 OPT ENG JI Opt. Eng. PD MAR PY 1995 VL 34 IS 3 BP 795 EP 813 DI 10.1117/12.194050 PG 19 WC Optics SC Optics GA QL475 UT WOS:A1995QL47500021 ER PT J AU ROSEN, J SALIK, B YARIV, A LIU, HK AF ROSEN, J SALIK, B YARIV, A LIU, HK TI PSEUDONONDIFFRACTING SLITLIKE BEAM AND ITS ANALOGY TO THE PSEUDONONDISPERSING PULSE SO OPTICS LETTERS LA English DT Article AB A new nonspreading beam is proposed for the case in which diffraction occurs only in one transverse coordinate. The beam has the shape of a pulse in one dimension and is constant in the other (slitlike shape). The intensity of the pulse's peak remains almost constant along a finite interval on the propagation axis. The proposed beam is analyzed and demonstrated experimentally. The analogy between this beam and the temporal pulse in a dispersive medium is discussed. C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. RP ROSEN, J (reprint author), CALTECH,MS 128-95,PASADENA,CA 91125, USA. RI Rosen, Joseph/F-1889-2012 OI Rosen, Joseph/0000-0002-9739-2180 NR 9 TC 32 Z9 33 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 MAR 1 PY 1995 VL 20 IS 5 BP 423 EP 425 DI 10.1364/OL.20.000423 PG 3 WC Optics SC Optics GA QK123 UT WOS:A1995QK12300001 PM 19859208 ER PT J AU AFZAL, RS SELKER, MD AF AFZAL, RS SELKER, MD TI SIMPLE HIGH-EFFICIENCY TEM(00) DIODE-LASER-PUMPED Q-SWITCHED LASER SO OPTICS LETTERS LA English DT Article AB A simple, efficient diode-laser-pumped and-switched Nd:YAG las;er is described that produces 2.25-mJ, TEM(00), 4-ns pulses up to 90 Hz with only 20 mJ of pump power. The laser has a zigzag slab geometry, side pumped with only one high-power quasi-cw diode bar. This performance approaches that of longitudinal pumping, demonstrating TEM(00) mode operation with long-pulse and and-switched slope efficiencies of 28% and 19%, respectively. Second and fourth-harmonic efficiencies of >50% and >20% from 1064 nm without the use of external focusing optics were also demonstrated. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NR 14 TC 19 Z9 20 U1 0 U2 3 PU OPTICAL SOC AMER PI WASHINGTON PA 2010 MASSACHUSETTS AVE NW, WASHINGTON, DC 20036 SN 0146-9592 J9 OPT LETT JI Opt. Lett. PD MAR 1 PY 1995 VL 20 IS 5 BP 465 EP 467 DI 10.1364/OL.20.000465 PG 3 WC Optics SC Optics GA QK123 UT WOS:A1995QK12300015 PM 19859222 ER PT J AU KANIK, I JAMES, GK AJELLO, JM AF KANIK, I JAMES, GK AJELLO, JM TI MEDIUM-RESOLUTION STUDIES OF EXTREME-ULTRAVIOLET EMISSION FROM CO BY ELECTRON-IMPACT SO PHYSICAL REVIEW A LA English DT Article ID CARBON-MONOXIDE; OSCILLATOR-STRENGTHS; CROSS-SECTIONS; INTERSTELLAR CLOUDS; DIPOLE-MOMENTS; 115 NM; EXCITATION; PHOTODISSOCIATION; ABSORPTION; STATES RP KANIK, I (reprint author), CALTECH, JET PROPULS LAB, PASADENA, CA 91109 USA. NR 32 TC 22 Z9 22 U1 0 U2 2 PU AMER PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD MAR PY 1995 VL 51 IS 3 BP 2067 EP 2074 DI 10.1103/PhysRevA.51.2067 PG 8 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA QN231 UT WOS:A1995QN23100048 ER PT J AU ORIENT, OJ CHUTJIAN, A MURAD, E AF ORIENT, OJ CHUTJIAN, A MURAD, E TI OBSERVATION OF CH A-(2)DELTA-]X (2)PI, AND B-(2)SIGMA(-)-]X (2)PI, EMISSIONS IN GAS-PHASE COLLISIONS OF FAST O(P-3) ATOMS WITH ACETYLENE SO PHYSICAL REVIEW A LA English DT Article C1 PHILLIPS LAB,WSCI,BEDFORD,MA 01731. RP ORIENT, OJ (reprint author), CALTECH,JET PROPULS LAB,PASADENA,CA 91109, USA. NR 11 TC 6 Z9 6 U1 0 U2 0 PU AMERICAN PHYSICAL SOC PI COLLEGE PK PA ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA SN 1050-2947 J9 PHYS REV A JI Phys. Rev. A PD MAR PY 1995 VL 51 IS 3 BP 2094 EP 2097 DI 10.1103/PhysRevA.51.2094 PG 4 WC Optics; Physics, Atomic, Molecular & Chemical SC Optics; Physics GA QN231 UT WOS:A1995QN23100051 ER PT J AU LIOU, WW SHIH, TH DUNCAN, BS AF LIOU, WW SHIH, TH DUNCAN, BS TI A MULTIPLE-SCALE MODEL FOR COMPRESSIBLE TURBULENT FLOWS SO PHYSICS OF FLUIDS LA English DT Article ID FREE SHEAR LAYERS; MIXING LAYERS C1 NASA,LEWIS RES CTR GRP,NYMA,BROOKPARK,OH 44142. RP LIOU, WW (reprint author), NASA,LEWIS RES CTR,ICOMP,CTR MODELING TURBULENCE & TRANSIT,CLEVELAND,OH 44135, USA. NR 37 TC 5 Z9 5 U1 0 U2 1 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 1070-6631 J9 PHYS FLUIDS JI Phys. Fluids PD MAR PY 1995 VL 7 IS 3 BP 658 EP 666 DI 10.1063/1.868588 PG 9 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA QH871 UT WOS:A1995QH87100017 ER PT J AU KASPI, V AF KASPI, V TI IS FUNDAMENTALS OF PHYSICS TOO VIOLENT SO PHYSICS TODAY LA English DT Letter RP KASPI, V (reprint author), JET PROPULS LAB,PASADENA,CA, USA. NR 0 TC 0 Z9 0 U1 0 U2 0 PU AMER INST PHYSICS PI WOODBURY PA CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 SN 0031-9228 J9 PHYS TODAY JI Phys. Today PD MAR PY 1995 VL 48 IS 3 BP 128 EP & DI 10.1063/1.2807963 PG 0 WC Physics, Multidisciplinary SC Physics GA QM377 UT WOS:A1995QM37700031 ER PT J AU MCCABE, JD AF MCCABE, JD TI LONG-HAUL COMMUNICATIONS SUPPORT FOR VISUALIZATION OF COMPUTATIONAL AEROSCIENCE SIMULATIONS SO PRESENCE-TELEOPERATORS AND VIRTUAL ENVIRONMENTS LA English DT Article AB This paper discusses the long-haul data communications requirements needed to support visualization of Computational Aeroscience (GAS) simulations. A scientific computing model is presented, from which current communications requirements are derived. This model is then expanded to describe the CAS collaborative visualization environment, in which scientists from multiple NASA centers will collaborate on multidisciplinary, lime-accurate simulations. An analysis of this model indicates that CAS data communications requirements will increase to 10-100 megabytes/sec by 1996. RP MCCABE, JD (reprint author), NASA,AMES RES CTR,DIV NUMER AERODYNAM SIMULAT,MOFFETT FIELD,CA 94035, USA. NR 12 TC 0 Z9 0 U1 0 U2 0 PU MIT PRESS PI CAMBRIDGE PA 55 HAYWARD ST JOURNALS DEPT, CAMBRIDGE, MA 02142 SN 1054-7460 J9 PRESENCE-TELEOP VIRT JI Presence-Teleoper. Virtual Env. PD SPR PY 1995 VL 4 IS 2 BP 110 EP 120 PG 11 WC Computer Science, Cybernetics; Computer Science, Software Engineering SC Computer Science GA QX730 UT WOS:A1995QX73000003 ER PT J AU HECHT, H PROFFITT, DR AF HECHT, H PROFFITT, DR TI THE PRICE OF EXPERTISE - EFFECTS OF EXPERIENCE ON THE WATER-LEVEL TASK SO PSYCHOLOGICAL SCIENCE LA English DT Article ID PERCEPTION; RECOGNITION; PERFORMANCE; PRINCIPLE; DYNAMICS; GENDER AB When shown a tilted container, people often fail to appreciate that the surface of the liquid contained within should remain horizontal with respect to the ground. This study investigated how amenable this bias is to experience in relevant everyday situations. Surprisingly, liquid surfaces that waitresses and bartenders considered natural deviated even more from horizontal than was the case for comparison groups. This finding is, to our knowledge, the only documented case in which performance declines with experience. We suggest that practical experience promotes a functionally relative perspective, in which the orientation of the liquid's surface is evaluated relative to that of its container as opposed to being related directly to the surrounding environment. The container-relative perspective, in turn, evokes a perceptual bias that is responsible for the systematic errors observed on this task. C1 UNIV VIRGINIA,CHARLOTTESVILLE,VA 22903. RP HECHT, H (reprint author), NASA,AMES RES CTR,MAIL STOP 262-3,MOFFETT FIELD,CA 94035, USA. RI Hecht, Heiko/H-3106-2011 NR 12 TC 43 Z9 43 U1 1 U2 3 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0956-7976 J9 PSYCHOL SCI JI Psychol. Sci. PD MAR PY 1995 VL 6 IS 2 BP 90 EP 95 DI 10.1111/j.1467-9280.1995.tb00312.x PG 6 WC Psychology, Multidisciplinary SC Psychology GA QR665 UT WOS:A1995QR66500004 ER PT J AU MCCLOSKEY, M RAPP, B YANTIS, S RUBIN, G BACON, WF DAGNELIE, G GORDON, B ALIMINOSA, D BOATMAN, DF BADECKER, W JOHNSON, DN TUSA, RJ PALMER, E AF MCCLOSKEY, M RAPP, B YANTIS, S RUBIN, G BACON, WF DAGNELIE, G GORDON, B ALIMINOSA, D BOATMAN, DF BADECKER, W JOHNSON, DN TUSA, RJ PALMER, E TI A DEVELOPMENTAL DEFICIT IN LOCALIZING OBJECTS FROM VISION SO PSYCHOLOGICAL SCIENCE LA English DT Article ID DYSLEXIA AB We describe a college student, A.H., with a developmental deficit in determining the location of objects from vision. The deficit is selective in that (a) localization from auditory or tactile information is intact; (b) A.H. reports the identity of mislocalized objects accurately; (c) visual localization errors preserve certain parameters of the target location; and (d) visual localization is severely impaired under certain stimulus conditions, but nearly intact under other conditions. These results bear on the representation and processing of location information in the visual system, and also have implications for understanding developmental dyslexia. C1 NASA,AMES RES CTR,MOFFETT FIELD,CA 94035. NIAAA,ROCKVILLE,MD 20852. RP MCCLOSKEY, M (reprint author), JOHNS HOPKINS UNIV,DEPT COGNIT SCI,BALTIMORE,MD 21218, USA. RI Yantis, Steven/A-7488-2009 NR 19 TC 27 Z9 27 U1 3 U2 6 PU CAMBRIDGE UNIV PRESS PI NEW YORK PA 40 WEST 20TH STREET, NEW YORK, NY 10011-4211 SN 0956-7976 J9 PSYCHOL SCI JI Psychol. Sci. PD MAR PY 1995 VL 6 IS 2 BP 112 EP 117 DI 10.1111/j.1467-9280.1995.tb00316.x PG 6 WC Psychology, Multidisciplinary SC Psychology GA QR665 UT WOS:A1995QR66500008 ER PT J AU ATKINSON, DH POLLACK, JB AF ATKINSON, DH POLLACK, JB TI GALILEO ENTRY PROBE RECOVERY OF FINE-STRUCTURE IN THE ZONAL WIND-PROFILE AT JUPITER SO RADIO SCIENCE LA English DT Article AB The algorithm developed to recover the zonal (east-west) wind profile at Jupiter by Doppler tracking of the Galileo probe is well established in theory and verified by computer simulation. We extend the Doppler wind recovery algorithm to include detection and extraction of microscale wind structure. When the probe encounters regions of high wind shear, turbulence, atmospheric waves, or nonsteady aerodynamics (buffeting) a rapidly varying component is introduced into the probe telemetry Doppler data. These effects can be isolated by their respective Doppler signatures. Analysis of residuals allows fine structure in the wind profile to be located and retrieved. The overall wind recovery is a three-step process: (1) The large-scale zonal wind profile is recovered by converting the probe telemetry frequency residuals (as caused by the Doppler effect) to a velocity and back-projecting it into the local horizontal east-west direction at the probe location. The zonal winds are derived from the velocity residuals by a least squares algorithm. (2) Regions of high zonal wind shear are recovered numerically relative to the large-scale wind structure and serve as a correction to the previously derived large-scale profile. (3) The probe trajectory is updated to reflect both the large- and small-scale wind structure, and the large-scale wind profile is recalculated. The Galileo Doppler wind experiment described previously and the wind microstructure retrieval algorithm outlined here are the only reasonable means by which the vertical profile of the zonal winds at Jupiter can be directly sampled. C1 NASA,AMES RES CTR,DIV SPACE SCI,MOFFETT FIELD,CA 94035. RP ATKINSON, DH (reprint author), UNIV IDAHO,DEPT ELECTR ENGN,MOSCOW,ID 83843, USA. NR 9 TC 0 Z9 0 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0048-6604 J9 RADIO SCI JI Radio Sci. PD MAR-APR PY 1995 VL 30 IS 2 BP 413 EP 422 DI 10.1029/94RS03162 PG 10 WC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications SC Astronomy & Astrophysics; Geochemistry & Geophysics; Meteorology & Atmospheric Sciences; Remote Sensing; Telecommunications GA QP240 UT WOS:A1995QP24000009 ER PT J AU MARKHAM, BL WILLIAMS, DL SCHAFER, JR WOOD, F KIM, MS AF MARKHAM, BL WILLIAMS, DL SCHAFER, JR WOOD, F KIM, MS TI RADIOMETRIC CHARACTERIZATION OF DIODE-ARRAY FIELD SPECTRORADIOMETERS SO REMOTE SENSING OF ENVIRONMENT LA English DT Article AB A study ii as conducted to evaluated the radiometric performance of two commercially available diode-array field spectroradiometers: the Spectron Engineering (SE) Model 590 that has been on she market for some 10 years and the several-year-old Analytical Spectral Devices (ASD) Personal Spectrometer (PS) 2. Both of these instruments provide rapid acquisition (similar to 1 s) of a spectrum in the visible to near-infrared region (similar to 0.4-1.1 mu m) and are field-portable. These evaluations included: spectral bandwidth, second-order effects suppression, signal to noise ratios, noise equivalent radiances, linearity of response with radiance and with integration time, temperature sensitivity, and polarization sensitivity In the configurations tested the SE590 instruments had a spectral bandwidth of about 16 nm full width at half-maximum the PS2 instruments, 3-4 nm. Neither of the instruments produced measurable second-order leakage. When viewing a barium-sulfate-coated integrating source internally illuminated with tungsten lamps, both instruments were able to obtain signal to noise ratios of 1000:1 or better between 500 m and 900 nm over most of the dynamic range provided by the sources when the integration time was optimized for the light level. Signal to noise dropped at shorter wavelengths in part due to the low energy provided by the source and at longer wavelengths due to the decrease in the detector response. In linearity tests all of the instruments generally agreed within 5% of the reference radiometer between 400 nm and 1000 nm; however, results were poorer at lower radiance levels and at wavelengths longer than 1000 nm or shorter than 400 nm. Both of the instruments rely on a shutter to measure their dark current, which is normally subtracted from the signal. However, closing the shutter on all of the instruments altered the dark current readings to some extent such that the dark current that teas subtracted was not correct. When the error in dark current is compensated for, she apparent linearity of the system improves considerably with weak signals. The SE590 systems showed significant polarization sensitivity of up to 25%, whereas the PS2 instruments did not. Movement of the fiber optic cable on the PS2 instruments did result in measurable signal changes. Both instruments also showed the temperature sensitivity typical of silicon detectors; i.e., increasing sensitivity at the longer wavelengths with higher temperature. C1 SCI SYST & APPLICAT INC,LANHAM,MD. UNIV MARYLAND,DEPT GEOG,COLLEGE PK,MD. RP MARKHAM, BL (reprint author), NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,CODE 923,GREENBELT,MD 20771, USA. RI Markham, Brian/M-4842-2013 OI Markham, Brian/0000-0002-9612-8169 NR 5 TC 21 Z9 21 U1 0 U2 2 PU ELSEVIER SCIENCE PUBL CO 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 MAR PY 1995 VL 51 IS 3 BP 317 EP 330 DI 10.1016/0034-4257(94)00108-Y PG 14 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA RB086 UT WOS:A1995RB08600001 ER PT J AU KWOK, R NGHIEM, SV YUEH, SH HUYNH, DD AF KWOK, R NGHIEM, SV YUEH, SH HUYNH, DD TI RETRIEVAL OF THIN ICE THICKNESS FROM MULTIFREQUENCY POLARIMETRIC SAR DATA SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID COMPLEX-DIELECTRIC-CONSTANT; SEA-ICE; MICROWAVE-FREQUENCIES; MODEL; SCATTERERS; BRINE; MEDIA; SNOW AB We discuss the observed C- and L-band polarimetric signatures of thin bead ice in one Synthetic Aperture Radar (SAR) Image based on the expected ice properties and results from a scattering model. In this article, we focus on thin ice with thicknesses in the range of 0-10 cm. The layered scattering model used here allows for the inclusion of surface and volume scattering contributions from a slush layer, an ice layer, and roughness at the interfaces. The sensitivity of the signatures to the model parameters is explored. A highly saline surface skim formed on the top surface during ice growth significantly affects the electromagnetic properties of the medium and helps to explain the magnitude of the copolarized returns at high incidence angles. Based on these model predictions, tee demonstrate an approach to retrieve the ice thickness from polarimetric SAR observations. The approach includes the training of a neural network with model predictions and using this neural network to estimate the ice thickness distribution using polarimetric observations from SAR data. The results from this ice thickness retrieval process are discussed. RP KWOK, R (reprint author), CALTECH,JET PROP LAB,4800 OAK GROVE DR,MS 300-235,PASADENA,CA 91109, USA. RI Kwok, Ron/A-9762-2008 OI Kwok, Ron/0000-0003-4051-5896 NR 30 TC 26 Z9 28 U1 0 U2 5 PU ELSEVIER SCIENCE PUBL CO 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 MAR PY 1995 VL 51 IS 3 BP 361 EP 374 DI 10.1016/0034-4257(94)00017-H PG 14 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA RB086 UT WOS:A1995RB08600005 ER PT J AU STARKS, PJ WALTERSHEA, EA SCHIEBE, FR MARKHAM, BL AF STARKS, PJ WALTERSHEA, EA SCHIEBE, FR MARKHAM, BL TI TEMPERATURE SENSITIVITY CHARACTERIZATION OF A SILICON DIODE-ARRAY SPECTROMETER SO REMOTE SENSING OF ENVIRONMENT LA English DT Article ID FIELD AB High spectral resolution remote sensing devices are frequently used to quantify the flux Of energy reflected from or transmitted through an optical medium. Their use requires careful calibration against a well-characterized standard. This study teas conducted to characterize temperature sensitivity of a typical silicon-detector-based spectroradiometer, demonstrate the potential errors due to temperature effects, and present a methodology to correct for temperature-induced errors. Three Spectron Engineering SE590 units were independently evaluated under varying temperatures at three separate institutions. A procedure for correcting calibration coefficients (radiance/count) as a function of temperature and wavelength teas developed and applied. The Evaluation showed that at wavelengths between 390 nm and 940 nm the calibration coefficients differed from each other by less than 5% among all ambient temperatures. At 1000 nm, the calibration coefficient decreases about 5% going from 25 degrees C to 35 degrees C and increases about 25% going from 25 degrees C to 0 degrees C. Wavebands below 390 nm responded chaotically to temperature. At ant! given wavelength above 940 nm the change in calibration coefficient value was a nearly linear function of temperature, an indication that a simple temperature correction can be applied. Calibration coefficients were linearly interpolated for each waveband greater than 940 nm at temperatures between temperature extremes imposed upon the instruments during the experiments. Linearly interpolated calibration coefficients were found to be within 4% of actual values. Users of silicon-detector-based spectroradiometers should be aware of potential errors in data due to temperature effects. C1 UNIV NEBRASKA,INST AGR & NAT RESOURCES,DEPT AGR METEOROL,LINCOLN,NE 68583. NASA,GODDARD SPACE FLIGHT CTR,BIOSPHER SCI BRANCH,GREENBELT,MD 20771. RP STARKS, PJ (reprint author), USDA ARS,NATL AGR WATER QUAL LAB,POB 1430,DURANT,OK 74702, USA. RI Markham, Brian/M-4842-2013 OI Markham, Brian/0000-0002-9612-8169 NR 11 TC 8 Z9 8 U1 0 U2 1 PU ELSEVIER SCIENCE PUBL CO 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 MAR PY 1995 VL 51 IS 3 BP 385 EP 389 DI 10.1016/0034-4257(94)00109-Z PG 5 WC Environmental Sciences; Remote Sensing; Imaging Science & Photographic Technology SC Environmental Sciences & Ecology; Remote Sensing; Imaging Science & Photographic Technology GA RB086 UT WOS:A1995RB08600007 ER PT J AU WARSHAWSKY, I AF WARSHAWSKY, I TI ONLINE DYNAMIC GAS PYROMETRY USING 2-THERMOCOUPLE PROBE SO REVIEW OF SCIENTIFIC INSTRUMENTS LA English DT Article ID TIME C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 14 TC 6 Z9 6 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 MAR PY 1995 VL 66 IS 3 BP 2619 EP 2624 DI 10.1063/1.1145598 PG 6 WC Instruments & Instrumentation; Physics, Applied SC Instruments & Instrumentation; Physics GA QM669 UT WOS:A1995QM66900037 ER PT J AU GARY, GA RABIN, D AF GARY, GA RABIN, D TI LINE-OF-SIGHT MAGNETIC-FLUX IMBALANCES CAUSED BY ELECTRIC CURRENTS SO SOLAR PHYSICS LA English DT Article ID ACTIVE REGIONS; FIELD LINES; INCLINATION AB Several physical and observational effects may contribute to the significant imbalances of magnetic flux that are often observed in active regions. We consider an effect not previously treated: the influence of electric currents in the photosphere. Electric currents can cause a line-of-sight flux imbalance because of the directionality of the magnetic field they produce. Currents associated with magnetic flux tubes produce larger imbalances than do smoothly-varying distributions of flux and current. We estimate the magnitude of this effect for current densities, total currents, and magnetic geometry consistent with observations. The expected imbalances lie approximately in the range 0-15%, depending on the character of the current-carrying fields and the angle from which they are viewed. Observationally, current-induced flux imbalances could be indicated by a statistical dependence of the imbalance on angular distance from disk center. A general study of magnetic flux balance in active regions is needed to determine the relative importance of other - probably larger effects such as dilute flux (too weak to measure or rendered invisible by radiative transfer effects), merging with weak background fields, and long-range connections between active regions. C1 NATL OPT ASTRON OBSERV,NATL SOLAR OBSERV,TUCSON,AZ 85726. RP GARY, GA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB ES82,HUNTSVILLE,AL 35812, USA. NR 24 TC 5 Z9 6 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 MAR PY 1995 VL 157 IS 1-2 BP 185 EP 197 DI 10.1007/BF00680616 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QZ388 UT WOS:A1995QZ38800012 ER PT J AU ROSENFELD, D ALTEROVITZ, SA AF ROSENFELD, D ALTEROVITZ, SA TI THE COMPOSITION DEPENDENCE OF THE CUTOFF FREQUENCIES OF UNGRADED SI1-XGEX/SI1-YGEY/SI1-XGEX HBTS SO SOLID-STATE ELECTRONICS LA English DT Article ID HETEROJUNCTION BIPOLAR-TRANSISTORS; SIGE-BASE; BAND-GAP; SILICON; ALLOYS; HETEROSTRUCTURES; PERFORMANCE; COLLECTOR; TRANSPORT; MOBILITY AB This paper presents a theoretical study of the composition dependence of the high frequency figures of merit of n-p-n homogeneous Heterojunction Bipolar Transistors (HBTs), based on SiGe alloys. Double heterostructure transistors with the same geometry and dopant profile but with different Ge concentrations in the emitter, base and collector, are compared. The composition dependencies of the emitter-to-collector transit time, the base-resistance collector-capacitance product, the associated unity current gain frequency (f(tau)) and the maximum frequency of oscillation (f(max)), are modeled and calculated. The computed results (of our structures and design) show that the composition dependencies of f(tau) and f(max) are non-monotonic. As the Ge composition in the emitter and collector layers is increased (and its concentration in the base is kept higher), f(tau) and f(max) first decrease, then remain constant and finally increase to attain their highest values. C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. NR 41 TC 4 Z9 4 U1 0 U2 0 PU PERGAMON-ELSEVIER SCIENCE LTD PI OXFORD PA THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB SN 0038-1101 J9 SOLID STATE ELECTRON JI Solid-State Electron. PD MAR PY 1995 VL 38 IS 3 BP 641 EP 651 DI 10.1016/0038-1101(94)00149-A PG 11 WC Engineering, Electrical & Electronic; Physics, Applied; Physics, Condensed Matter SC Engineering; Physics GA QK015 UT WOS:A1995QK01500016 ER PT J AU ORSI, JA WERTHEIMER, AC AF ORSI, JA WERTHEIMER, AC TI MARINE VERTICAL-DISTRIBUTION OF JUVENILE CHINOOK AND COHO SALMON IN SOUTHEASTERN ALASKA SO TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY LA English DT Article AB Vertical distributions of chinook salmon Oncorhynchus tshawytscha of marine ages x.0, x.1, and x.2 and coho salmon O. kisutch of age x.0 are reported for the marine waters of southeastern Alaska. (The number or letter preceding the decimal point indicates number of winters spent in freshwater, that following the decimal point indicates winters spent in salt water.) Understanding vertical distribution of prerecruit salmon may be useful in minimizing fishery bycatch. Salmon were caught to a depth of 36.6 m from chartered commercial power trollers fishing small hooks and lures. Sampling occurred throughout inside waters of the Alexander Archipelago and adjacent coastal waters during September 1986 and in inside waters near Ketchikan during February, May, and September 1987. Vertical distribution of salmon differed significantly by species and age-group: in September, age-x.0 coho salmon (mean fork length, 28.4 cm) were caught shallower than age-x.0 chinook salmon (27.3 cm); age-x.1 (44.2 cm) and age-x.2 (60.4 cm) chinook salmon were deeper than age-x.0 chinook salmon. Length of chinook salmon increased significantly with depth. Vertical distribution did not differ significantly between ocean-type and stream-type fish or between sexes. Chinook salmon were significantly deeper in February than in September or May and significantly deeper in September than in May. Our findings suggest that encounter rates of prerecruit chinook salmon and coho salmon in chinook salmon troll fisheries could be minimized by restricting fishing to depths of 30 m or more during selected periods. RP ORSI, JA (reprint author), ALASKA FISHERIES SCI CTR,AUKE BAY LAB,NATL MARINE FISHERIES SERV,11305 GLACIER HIGHWAY,JUNEAU,AK 99801, USA. NR 31 TC 22 Z9 22 U1 0 U2 5 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 SN 0002-8487 J9 T AM FISH SOC JI Trans. Am. Fish. Soc. PD MAR PY 1995 VL 124 IS 2 BP 159 EP 169 DI 10.1577/1548-8659(1995)124<0159:MVDOJC>2.3.CO;2 PG 11 WC Fisheries SC Fisheries GA QN160 UT WOS:A1995QN16000001 ER PT J AU EILER, JH AF EILER, JH TI A REMOTE SATELLITE-LINKED TRACKING SYSTEM FOR STUDYING PACIFIC SALMON WITH RADIO TELEMETRY SO TRANSACTIONS OF THE AMERICAN FISHERIES SOCIETY LA English DT Article AB A remote tracking system with a satellite uplink was used to study the movements of adult chinook salmon Oncorhynchus tshawytscha and coho salmon O. kisutch in the large, isolated Taku River in Alaska and British Columbia. Salmon were tagged with pulse-coded radio transmitters; 10 codes identified individual fish on each of 52 frequencies. Remote tracking stations automatically collected, processed, and transferred telemetry data via a computer-controlled receiver. A satellite uplink was used to retrieve the data for within-season analysis. Three hundred six chinook salmon were tracked upriver in 1990 and 351 coho salmon in 1992. Coho salmon could not have been tracked with conventional methods due to the inclement fall weather and mountainous terrain typical of this area. The stations recorded 98-100% of the radio-tagged fish that moved past. Tracking success was much higher than in previous studies in which fish were tracked exclusively from aircraft. The remote tracking system is an effective method for precisely tracking large numbers of salmon in large, inaccessible rivers, and it has numerous applications to fisheries research. RP EILER, JH (reprint author), ALASKA FISHERIES SCI CTR,AUKE BAY LAB,NATL MARINE FISHERIES SERV,11305 GLACIER HIGHWAY,JUNEAU,AK 99801, USA. NR 25 TC 20 Z9 23 U1 0 U2 3 PU AMER FISHERIES SOC PI BETHESDA PA 5410 GROSVENOR LANE SUITE 110, BETHESDA, MD 20814-2199 SN 0002-8487 J9 T AM FISH SOC JI Trans. Am. Fish. Soc. PD MAR PY 1995 VL 124 IS 2 BP 184 EP 193 DI 10.1577/1548-8659(1995)124<0184:ARSLTS>2.3.CO;2 PG 10 WC Fisheries SC Fisheries GA QN160 UT WOS:A1995QN16000003 ER PT J AU SPALL, RE GATSKI, TB AF SPALL, RE GATSKI, TB TI NUMERICAL-CALCULATIONS OF 3-DIMENSIONAL TURBULENT VORTEX BREAKDOWN SO INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS LA English DT Article DE VORTEX BREAKDOWN; TURBULENCE; COMPUTATIONAL FLUID DYNAMICS ID NAVIER-STOKES EQUATIONS; SWIRLING FLOW; COMBUSTION; INLET AB Numerical solutions to the three-dimensional, unsteady, incompressible Reynolds-averaged Navier-Stokes equations have been obtained for bubble-type vortex breakdown. Two different turbulence models were employed: (1) standard K-epsilon and (2) an explicit, regularized algebraic Reynolds stress model. Results are computed at a Reynolds number of 10,000. The algebraic Reynolds stress model produced a breakdown bubble with a larger length-to-diameter ratio than did the K-epsilon model. Breakdown also occurred at lower levels of adverse pressure gradient for the algebraic stress model than for the K-epsilon model. In each case single-cell breakdown structures resulted. This is contrasted with numerical calculations for laminar breakdown which reveal the existence of complex multicell bubble breakdown structures. C1 NASA,LANGLEY RES CTR,THEORET FLOW PHYS BRANCH,HAMPTON,VA 23681. RP SPALL, RE (reprint author), UNIV SO ALABAMA,DEPT ENGN MECH,EGCB 212,MOBILE,AL 36688, USA. NR 30 TC 10 Z9 10 U1 0 U2 1 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 FEB 28 PY 1995 VL 20 IS 4 BP 307 EP 318 DI 10.1002/fld.1650200404 PG 12 WC Computer Science, Interdisciplinary Applications; Mathematics, Interdisciplinary Applications; Mechanics; Physics, Fluids & Plasmas SC Computer Science; Mathematics; Mechanics; Physics GA QH812 UT WOS:A1995QH81200003 ER PT J AU RAJ, SV AF RAJ, SV TI A PRELIMINARY ASSESSMENT OF THE PROPERTIES OF A CHROMIUM SILICIDE ALLOY FOR AEROSPACE APPLICATIONS SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING LA English DT Article; Proceedings Paper CT 3rd International Conference on High Temperature Intermetallics CY MAY 16-19, 1994 CL SAN DIEGO, CA SP ASM INT DE CHROMIUM; SILICON; ALLOYS; AEROSPACE APPLICATIONS ID MOLYBDENUM DISILICIDE; COMPOSITES; OXIDATION AB A preliminary assessment of the physical, mechanical and oxidation properties of a two-phase Cr3Si ahoy macro-alloyed with Mo for potential aerospace applications is discussed. Detailed cyclic, isothermal and low temperature ''pest'' oxidation studies conducted between 773 and 1773 K revealed that the alloy has excellent oxidation properties due to the formation of dual protective oxides scales of Cr2O3 at low temperatures and SiO2 at high temperatures. The alloy also lasted at least 100 cycles at 1473 K under the action of a 0.3 mach combustion name in burner rig tests. The compressive brittle-to-ductile transition temperature of the alloy is about 1500 K. The compressive creep strength of the as-cast alloy at 1500 K is as good or better than MoSi2 reinforced with either SiCp or SiCw, respectively, while those of the powder metallurgically processed alloys are comparable only to the unreinforced MoSi2. The room temperature fracture toughness of the alloy was determined to be 2.5 MPa m(1/2). RP RAJ, SV (reprint author), NASA, LEWIS RES CTR, MS 49-1, CLEVELAND, OH 44135 USA. NR 21 TC 37 Z9 42 U1 0 U2 4 PU ELSEVIER SCIENCE SA PI LAUSANNE PA PO BOX 564, 1001 LAUSANNE, SWITZERLAND SN 0921-5093 J9 MAT SCI ENG A-STRUCT JI Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process. PD FEB 28 PY 1995 VL 192 BP 583 EP 589 DI 10.1016/0921-5093(94)03281-5 PG 7 WC Nanoscience & Nanotechnology; Materials Science, Multidisciplinary; Metallurgy & Metallurgical Engineering SC Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering GA QR883 UT WOS:A1995QR88300009 ER PT J AU MITCHELL, BE LELE, SK MOIN, P AF MITCHELL, BE LELE, SK MOIN, P TI DIRECT COMPUTATION OF THE SOUND FROM A COMPRESSIBLE CO-ROTATING VORTEX PAIR SO JOURNAL OF FLUID MECHANICS LA English DT Article ID AERODYNAMIC SOUND; EMISSION; GENERATION; COLLISION; MERGER; RINGS AB The far-field sound generated by compressible co-rotating vortices is computed by direct computation of the unsteady compressible Navier-Stokes equations on a computational domain that extends to two acoustic wavelengths in all directions. The vortices undergo a period of co-rotation followed by a sudden merger. The directly computed far-field sound is compared to the prediction of the acoustic analogy due to Mohring (1978, 1979), a modified form of the analogy developed by Lighthill (1952), and an acoustic analogy derived by Powell (1964). All three predictions are in excellent agreement with the simulation. Results of far-field pressure fluctuations from an acoustically non-compact, co-rotating vortex pair are also presented. In this case, the vortex sound theory over-predicts the sound by 65% in accordance with the analysis of Yates (1978). C1 STANFORD UNIV,DEPT AERONAUT & ASTRONAUT,STANFORD,CA 94305. NASA,AMES RES CTR,AMES,IA. RP MITCHELL, BE (reprint author), STANFORD UNIV,DEPT MECH ENGN,STANFORD,CA 94305, USA. NR 33 TC 82 Z9 89 U1 0 U2 3 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 FEB 25 PY 1995 VL 285 BP 181 EP 202 DI 10.1017/S0022112095000504 PG 22 WC Mechanics; Physics, Fluids & Plasmas SC Mechanics; Physics GA QK091 UT WOS:A1995QK09100008 ER PT J AU KRASNOPOLSKY, VA AF KRASNOPOLSKY, VA TI UNIQUENESS OF A SOLUTION OF A STEADY-STATE PHOTOCHEMICAL PROBLEM - APPLICATIONS TO MARS SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID MARTIAN ATMOSPHERE; WATER-VAPOR; PLANETARY-ATMOSPHERES; PHOBOS SPACECRAFT; MOLECULAR-OXYGEN; CROSS-SECTION; O-2 DAYGLOW; ESCAPE; HYDROGEN; ABUNDANCE AB Based on the conservation of chemical elements in chemical reactions, a rule is proved that the number of boundary conditions given by densities and/or nonzero velocities should not be less than the number of chemical elements in the system, and the boundary conditions for species given by densities and velocities should include all elements in the system. Applications of this rule to Mars are considered. It is shown, that the problem of the CO2-H2O chemistry in the lower and middle atmosphere of Mars, say, in the range of 0-80 km does not have a unique solution, if only CO2 and H2O densities are given at the lower boundary, and the remaining boundary conditions are fluxes. Two examples of models of this type are discussed. These models fit the same boundary conditions; are balanced with a relative accuracy of 10(-4) for H-2 (and much better for other species), and predict O-2, CO, and H-2 mixing ratios which differ by orders of magnitude. One more species density, e.g., that of O-2, should be specified at the boundary to obtain a unique solution. The situation is better if the upper boundary is extended to the exobase where thermal escape velocities of H and H-2 can be specified. In this case, however, either the oxygen nonthermal escape rate (and hence the total hydrogen escape rate) or the O-2 (or other species) density at the surface should be given as a boundary condition. Two models of the photochemistry of the Martian atmosphere, with and without nitrogen chemistry, are considered. The oxygen nonthermal escape rate of 1.2x10(8) cm(-2)s(-1) is given at 240 km and is balanced with the total hydrogen escape rate within an uncertainty of 1% for both models. Both models fit the measured O-2 and CO mixing ratios, the O-3 abundance, and the O-2 1.27-mu m dayglow almost within the uncertainties of the measured values, though the model without nitrogen chemistry fits better. The importance of nitrogen chemistry in the lower and middle atmosphere of Mars depends on a fine balance between production of NO and N in the upper atmosphere which is not known within the required accuracy. RP KRASNOPOLSKY, VA (reprint author), NASA, GODDARD SPACE FLIGHT CTR, NATL RES COUNCIL, CODE 693, GREENBELT, MD 20771 USA. RI Krasnopolsky, Vladimir/L-5085-2013 NR 56 TC 45 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-PLANET JI J. Geophys. Res.-Planets PD FEB 25 PY 1995 VL 100 IS E2 BP 3263 EP 3276 DI 10.1029/94JE03283 PG 14 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QK383 UT WOS:A1995QK38300004 ER PT J AU VEMPATI, RK MORRIS, RV LAUER, HV HELMKE, PA AF VEMPATI, RK MORRIS, RV LAUER, HV HELMKE, PA TI REFLECTIVITY AND OTHER PHYSICOCHEMICAL PROPERTIES OF MN-SUBSTITUTED GOETHITES AND HEMATITES SO JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS LA English DT Article ID UNIT-CELL DIMENSIONS; IRON-OXIDES; A1-SUBSTITUTED HEMATITES; MOSSBAUER-SPECTRA; MORIN TRANSITION; A1 SUBSTITUTION; X-RAY; ALUMINUM; MANGANESE; AL AB Goethite-bearing samples with values of Mn-s (Mn/(Mn+Fe) mole fraction) up to 0.206 were synthesized by precipitation from alkaline solution. Samples with Mn-s less than or equal to 0.061 were single-phase Mn-goethites; samples with higher Mn-s values contained another Mn-bearing phase (probably jacobsite). Mn-hematites were prepared by dehydroxylation of corresponding Mn-goethites at 500 degrees C. Orthorhombic a and b unit cell dimensions of Mn-goethites changed in a linear manner with Mn-s, but not at rates predicted by the Vegard law. Hexagonal unit cell dimensions of Mn-hematites did not vary with Mn-s. Mossbauer parameters isomer shift (IS), quadrupole splitting (QS), and hyperfine field (B-hf) were measured at 293 and 15 K. For all single-phase Mn-goethites and Mn-hematites (Mn-s less than or equal to 0.061), magnetic splitting was observed at both temperatures. At 293 K, small but systematic decreases in B-hf were observed with increasing Mn substitution; IS and QS were not dependent on Mn-s. Mn substitution strongly lowered the Morin transition temperature of hematite. At 15 K, the Morin transition was not present for Mn-s > 0.020(4). The saturation magnetization of Mn-goethites and Mn-hematites (Mn-s less than or equal to 0.061) was the expected zero (within error) for antiferromagnetic goethite and for hematites obtained from dehydroxylation of goethites. Mn-goethites with Mn-s > 0.061 were magnetic because of the presence of strongly magnetic jacobsite. For reflectivity spectra, bands resulting from Mn3+ were centered near 454 and 596 nm for Mn-goethites and near 545 and 700 nm for Mn-hematites. There is evidence for a similar to 700 nm band in spectral data for Martian bright regions, but association of it with Mn3+ is not a unique interpretation. Comparison of laboratory and Martian spectral data implies that Mn-s < 0.032 for the Mn3+ content of Martian hematites. C1 UNIV WISCONSIN,DEPT SOIL SCI,MADISON,WI 53706. LOCKHEED ENGN & SCI CO,HOUSTON,TX 77058. NASA,LYNDON B JOHNSON SPACE CTR,PLANETARY SCI BRANCH,HOUSTON,TX 77058. RP VEMPATI, RK (reprint author), LAMAR UNIV,DEPT CHEM,BEAUMONT,TX 77705, USA. NR 73 TC 11 Z9 11 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-PLANET JI J. Geophys. Res.-Planets PD FEB 25 PY 1995 VL 100 IS E2 BP 3285 EP 3295 DI 10.1029/94JE02195 PG 11 WC Geochemistry & Geophysics SC Geochemistry & Geophysics GA QK383 UT WOS:A1995QK38300006 ER PT J AU VILAS, F AF VILAS, F TI ASTEROIDS, COMETS, METEORS 1993 - MILANI,A, DIMARTINO,M, CELLINO,A SO SCIENCE LA English DT Book Review RP VILAS, F (reprint author), NASA,LYNDON B JOHNSON SPACE CTR,HOUSTON,TX 77058, USA. NR 1 TC 0 Z9 0 U1 0 U2 0 PU AMER ASSOC ADVANCEMENT SCIENCE PI WASHINGTON PA 1200 NEW YORK AVE, NW, WASHINGTON, DC 20005 USA SN 0036-8075 J9 SCIENCE JI Science PD FEB 24 PY 1995 VL 267 IS 5201 BP 1193 EP 1194 DI 10.1126/science.267.5201.1193 PG 2 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QJ237 UT WOS:A1995QJ23700047 PM 17789199 ER PT J AU ANICICH, VG SEN, AD HUNTRESS, WT MCEWAN, MJ AF ANICICH, VG SEN, AD HUNTRESS, WT MCEWAN, MJ TI ASSOCIATION REACTIONS AT LOW-PRESSURE .5. THE CH3+/HCN SYSTEM - A FINAL WORD SO JOURNAL OF CHEMICAL PHYSICS LA English DT Article ID RADIATIVE ASSOCIATION; RATE COEFFICIENTS; ION; DEPENDENCE; CLOUDS C1 UNIV CANTERBURY,DEPT CHEM,CHRISTCHURCH 1,NEW ZEALAND. RP ANICICH, VG (reprint author), CALTECH,JET PROP LAB,PASADENA,CA 91109, USA. NR 15 TC 18 Z9 18 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 FEB 22 PY 1995 VL 102 IS 8 BP 3256 EP 3261 DI 10.1063/1.468636 PG 6 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QH967 UT WOS:A1995QH96700026 ER PT J AU NOEVER, DA CRONISE, RJ MATSOS, HC NIKORA, VI AF NOEVER, DA CRONISE, RJ MATSOS, HC NIKORA, VI TI BIOCONVECTIVE PERCOLATION ON AN INCOMPLETE VORONOI GRID SO JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL LA English DT Letter ID PATTERNS; CELLS AB Bioconvection is a fluid instability common to many biological organisms including swimming bacteria, alga and protozoa The statistics of bioconvective pattern formation is tested against percolation models for space-filling. A percolation threshold is found (p = 0.63) and compared to theoretical point distributions for random tesselations. Simulations reveal that a percolation backbone defines a complete path across the observation window but remains incomplete as an equal partitioning grid (Voronoi diagram). The generic development of incomplete Voronoi grids and their yet unknown statistical properties captures some interest as an alternative to traditional point-based lattices. C1 MOLDOVA GEOPHYS INST,KISHINEV,MOLDOVA. RP NOEVER, DA (reprint author), NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,BIOPHYS BRANCH,ES-76,HUNTSVILLE,AL 35812, USA. NR 15 TC 2 Z9 2 U1 0 U2 2 PU IOP PUBLISHING LTD PI BRISTOL PA TECHNO HOUSE, REDCLIFFE WAY, BRISTOL, ENGLAND BS1 6NX SN 0305-4470 J9 J PHYS A-MATH GEN JI J. Phys. A-Math. Gen. PD FEB 21 PY 1995 VL 28 IS 4 BP L115 EP L118 DI 10.1088/0305-4470/28/4/001 PG 4 WC Physics, Multidisciplinary; Physics, Mathematical SC Physics GA QK641 UT WOS:A1995QK64100001 ER PT J AU MEKLER, Y KAUFMAN, YJ AF MEKLER, Y KAUFMAN, YJ TI POSSIBLE CAUSES OF CALIBRATION DEGRADATION OF THE ADVANCED VERY HIGH-RESOLUTION RADIOMETER VISIBLE AND NEAR-INFRARED CHANNELS SO APPLIED OPTICS LA English DT Article DE AVHRR; CALIBRATION; COSMIC DUST; OPTICAL FILTERS ID AVHRR; NOAA-7 AB Gradual deterioration of calibration of the Advanced Very High Resolution Radiometer (AVHRR) can be explained by the erasion of the scanning mirror as a result of interaction with interplanetary dust. Other elements of the instrument (optical filters, detector, electronics) were also examined for their behavior in space conditions and were found most likely to be stable and not responsible for the decrease in sensitivity. Calculations show that the erosion of the scanning mirror is of the order of 4.5% per year, although this erosion is very variable because of the variability of the density of interplanetary dust. This erosion can easily explain the 3-5% per year deterioration of the AVHRR sensors on NOAA-7 and NOAA-9. C1 TEL AVIV UNIV,DEPT GEOPHYS & PLANETARY SCI,IL-69978 RAMAT AVIV,ISRAEL. RP MEKLER, Y (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 913,GREENBELT,MD 20771, USA. NR 14 TC 5 Z9 6 U1 5 U2 6 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 20 PY 1995 VL 34 IS 6 BP 1059 EP 1062 PG 4 WC Optics SC Optics GA QG837 UT WOS:A1995QG83700024 PM 21037634 ER PT J AU BUSCHER, DF ARMSTRONG, JT HUMMEL, CA QUIRRENBACH, A MOZURKEWICH, D JOHNSTON, KJ DENISON, CS COLAVITA, MM SHAO, M AF BUSCHER, DF ARMSTRONG, JT HUMMEL, CA QUIRRENBACH, A MOZURKEWICH, D JOHNSTON, KJ DENISON, CS COLAVITA, MM SHAO, M TI INTERFEROMETRIC SEEING MEASUREMENTS ON MT WILSON - POWER SPECTRA AND OUTER SCALES SO APPLIED OPTICS LA English DT Article ID GROUND-BASED TELESCOPES; ATMOSPHERIC-TURBULENCE; RESOLUTION LIMITS; LA-PALMA AB We have measured power spectra of atmospheric phase fluctuations with the Mark. III stellar interferometer on Mt. Wilson under a wide variety of seeing conditions. On almost all nights, the high-frequency portions of the temporal power spectra closely follow the form predicted by the standard Kolmogorov-Tatarski model. At lower frequencies, a variety of behavior is observed. On a few nights, the spectra clearly exhibit the low-frequency flattening characteristic of turbulence with an outer-scale length of the order of 30 m. On other nights, examination of individual spectra yields no strong evidence of an outer scale less than a few kilometers in size, but comparison of the spectra on different interferometer baselines shows a saturation of the spatial structure function on long baselines. This saturation is consistent with the assumption of an outer-scale length similar to that derived for the nights when low-frequency flattening of the spectra is clearly seen. We discuss possible explanations of this behavior and conclude that power spectra from a single interferometer baseline are a poor diagnostic for the effective outer scale compared with multiple-baseline spectra. C1 UNIV SPACE RES ASSOC,WASHINGTON,DC 20024. USN,RES LAB,DIV REMOTE SENSING,WASHINGTON,DC 20375. SFA INC,LANDOVER,MD 20785. JET PROPULS LAB,PASADENA,CA 91109. RP BUSCHER, DF (reprint author), USN OBSERV,RES LAB,OPT INTERFEROMETER PROJECT,AD5,3450 MASSACHUSETTS AVE NW,WASHINGTON,DC 20392, USA. NR 25 TC 50 Z9 50 U1 2 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 FEB 20 PY 1995 VL 34 IS 6 BP 1081 EP 1096 PG 16 WC Optics SC Optics GA QG837 UT WOS:A1995QG83700027 PM 21037637 ER PT J AU VONMONTIGNY, C BERTSCH, DL CHIANG, J DINGUS, BL ESPOSITO, JA FICHTEL, CE FIERRO, JM HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF NOLAN, PL RADECKE, HD SCHNEID, E SREEKUMAR, P THOMPSON, DJ WILLIS, T AF VONMONTIGNY, C BERTSCH, DL CHIANG, J DINGUS, BL ESPOSITO, JA FICHTEL, CE FIERRO, JM HARTMAN, RC HUNTER, SD KANBACH, G KNIFFEN, DA LIN, YC MATTOX, JR MAYERHASSELWANDER, HA MICHELSON, PF NOLAN, PL RADECKE, HD SCHNEID, E SREEKUMAR, P THOMPSON, DJ WILLIS, T TI HIGH-ENERGY GAMMA-RAY EMISSION FROM ACTIVE GALAXIES - EGRET OBSERVATIONS AND THEIR IMPLICATIONS SO ASTROPHYSICAL JOURNAL LA English DT Review DE BL LACERTAE OBJECTS, GENERAL; GALAXIES, ACTIVE; GAMMA RAYS, OBSERVATIONS; QUASARS, GENERAL ID EXTRAGALACTIC RADIO-SOURCES; LACERTAE OBJECT MARKARIAN-421; ROTATING COMPACT OBJECTS; GALACTIC NUCLEI; RELATIVISTIC JETS; X-RAY; BLACK-HOLE; MULTIFREQUENCY OBSERVATIONS; HYDROMAGNETIC FLOWS; RADIATION AB The energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma-Ray Observatory has so far detected, with a high degree of certainty, 33 active galactic nuclei (AGNs) in high-energy gamma rays (E > 100 MeV) during Phase I (91/16/05-92/17/11) and Phase II (92/17/11-93/07/09). There are detections of 11 other active galaxies with lesser significance. Of the sources detected, the majority are quasars and six are usually classified as BL Lacertae (BL Lac) objects. They seem to be all members of the blazar class a rather well defined subclass of AGN. To aid attempts at relating the observed properties of the EGRET sources to physical models of AGNs, a summary of EGRET AGN observations is presented. This summary includes gamma-ray spectra and time-dependent gamma-ray fluxes of detected sources. For sources where the information is available in the literature, multifrequency spectra covering the range from radio to gamma rays are also included. Constraints are discussed which the EGRET observations place upon various emission models. Finally, the contribution of AGNs to the diffuse extragalactic gamma-ray emission is reexamined in light of the EGRET observations. C1 MAX PLANCK INST EXTRATERR PHYS,D-80740 GARCHING,GERMANY. STANFORD UNIV,HANSEN EXPTL PHYS LAB,STANFORD,CA 94305. HAMPDEN SYDNEY COLL,HAMPDEN SYDNEY,VA 23943. GRUMMAN AEROSP CORP,BETHPAGE,NY 11714. UNIV SPACE RES ASSOC,ASTRON PROGRAMS,COMPTON OBSERV,CTR SCI SUPPORT,GREENBELT,MD 20771. RP VONMONTIGNY, C (reprint author), NASA,GODDARD SPACE FLIGHT CTR,UNIV SPACE RES ASSOC,CODE 662,GREENBELT,MD 20771, USA. RI Nolan, Patrick/A-5582-2009; Hunter, Stanley/D-2942-2012; Thompson, David/D-2939-2012; OI Thompson, David/0000-0001-5217-9135; Dingus, Brenda/0000-0001-8451-7450 NR 144 TC 395 Z9 396 U1 1 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 FEB 20 PY 1995 VL 440 IS 2 BP 525 EP 553 DI 10.1086/175294 PN 1 PG 29 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG505 UT WOS:A1995QG50500010 ER PT J AU XIE, TL ALLEN, M LANGER, WD AF XIE, TL ALLEN, M LANGER, WD TI TURBULENT-DIFFUSION AND ITS EFFECTS ON THE CHEMISTRY OF MOLECULAR CLOUDS SO ASTROPHYSICAL JOURNAL LA English DT Article DE DIFFUSION; ISM, ABUNDANCES; ISM, CLOUDS; ISM, MOLECULES; MOLECULAR PROCESSES; TURBULENCE ID DENSE INTERSTELLAR CLOUDS; INTER-STELLAR CLOUDS; GAS-PHASE CHEMISTRY; MASS STAR-FORMATION; ATOMIC CARBON; DISSOCIATIVE RECOMBINATION; PHOTODISSOCIATION REGIONS; DARK CLOUDS; MODEL; ABUNDANCES AB Turbulence in molecular clouds is well recognized, but the resultant diffusive transport and its effects on the chemical structure of the clouds have not been extensively investigated. We present in this article a study using the mixing-length approximation of the effects of turbulent diffusion on the chemical structure of a representative dark molecular cloud. With a diffusion term in the continuity equation for each species, we model the time-dependent gas-phase chemistry in a dense molecular cloud with fixed density and temperature profiles. We estimate the diffusion coefficient based on the observed turbulence in molecular clouds and find that diffusive processes significantly modify the predicted chemical abundances in the dense interiors of molecular clouds, increasing the abundances for C and C+ and most carbon-bearing species and lowering the abundances for some other species such as H2O and O-2. These results, which can be explained in the context of the existing ion-neutral reaction scheme in terms of electron abundance changes due to diffusion, appear to agree with observations. C1 CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. CALTECH, DIV GEOL & PLANETARY SCI, PASADENA, CA 91125 USA. NR 100 TC 94 Z9 95 U1 0 U2 0 PU IOP PUBLISHING LTD PI BRISTOL PA TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND SN 0004-637X EI 1538-4357 J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 1995 VL 440 IS 2 BP 674 EP 685 DI 10.1086/175305 PN 1 PG 12 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG505 UT WOS:A1995QG50500021 ER PT J AU SANDFORD, SA PENDLETON, YJ ALLAMANDOLA, LJ AF SANDFORD, SA PENDLETON, YJ ALLAMANDOLA, LJ TI THE GALACTIC DISTRIBUTION OF ALIPHATIC-HYDROCARBONS IN THE DIFFUSE INTERSTELLAR-MEDIUM SO ASTROPHYSICAL JOURNAL LA English DT Article DE INFRARED, ISM, LINES AND BANDS; ISM, MOLECULES ID SUPER-NOVA REMNANTS; ABUNDANCE GRADIENT; MU-M; INFRARED OBSERVATIONS; CHEMICAL EVOLUTION; ABSORPTION FEATURE; OPTICAL-EMISSION; SPECTROSCOPY; EXTINCTION; GRAINS AB The infrared absorption feature near 2950 cm(-1) (3.4 mu m), characteristic of dust in the diffuse interstellar medium (ISM), is attributed to C-H stretching vibrations of aliphatic hydrocarbons. We show here that the strength of the band does not scale linearly with visual extinction everywhere, but instead increases more rapidly for objects near the center of the Galaxy, a behavior that parallels that of the Si-O stretching band due to silicate materials in the diffuse ISM. This implies that the grains responsible for the diffuse medium aliphatic C-H and silicate Si-O stretching bands are different from those responsible for much of the observed visual extinction. It also suggests that the distribution of the carbonaceous component of the diffuse ISM is not uniform throughout the Galaxy, but instead may increase in density toward the center of the Galaxy. The similar behavior of the C-H and Si-O stretching bands suggests that these two components may be coupled, perhaps in the form of silicate-core, organic-mantle grains. Several possible models of the distribution of this material are presented and it is demonstrated that the inner parts of the Galaxy has a carrier density that is 5 to 35 times higher than in the local ISM. Depending on the model used, the density of aliphatic material in the local ISM is found to be about 1 to 2-CH3 groups m(-3) and about 2 to 5-CH2-groups m(-3). These densities are consistent with the strengths of the 2955 and 2925 cm(-1) (3.38 and 3.42 mu m) subfeatures (due to -CH3 and -CH2- groups, respectively) within the overall 2950 cm(-1) (3.4 mu m) band being described by the relations A(upsilon)/tau((2955 cm-1)) = 270 +/- 40 and A(upsilon)/tau((2925 cm?(-1))) = 250 +/- 40 in the local diffuse ISM. RP SANDFORD, SA (reprint author), NASA,AMES RES CTR,MAIL STOP 245-6,MOFFETT FIELD,CA 94035, USA. NR 50 TC 68 Z9 70 U1 0 U2 5 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 1995 VL 440 IS 2 BP 697 EP 705 DI 10.1086/175307 PN 1 PG 9 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG505 UT WOS:A1995QG50500023 PM 11538444 ER PT J AU JUNG, YD LEE, KS AF JUNG, YD LEE, KS TI SCREENING EFFECTS ON NONRELATIVISTIC BREMSSTRAHLUNG IN THE SCATTERING OF ELECTRONS BY NEUTRAL ATOMS SO ASTROPHYSICAL JOURNAL LA English DT Article DE ATOMIC PROCESSES; RADIATION MECHANISMS, NONTHERMAL AB Atomic screening effects on nonrelativistic electron-atom bremsstrahlung radiation are investigated using a simple analytic solution of the Thomas-Fermi model for many-electron atoms. The Born approximation is assumed for the initial and final states of the projectile electron, The results show that the screening effect is important in the soft radiation region and is decreasing with increasing radiation. These results help provide correct information about the behavior of bound electrons in the target atom in bremsstrahlung processes. C1 NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,HUNTSVILLE,AL 35812. HANYANG UNIV,DEPT PHYS,KYONGGI DO 425791,SOUTH KOREA. NR 10 TC 3 Z9 3 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 1995 VL 440 IS 2 BP 830 EP 833 DI 10.1086/175318 PN 1 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG505 UT WOS:A1995QG50500034 ER PT J AU ZARRO, DM MARISKA, JT DENNIS, BR AF ZARRO, DM MARISKA, JT DENNIS, BR TI TESTING THE DC-ELECTRIC FIELD MODEL IN A SOLAR-FLARE OBSERVED BY YOHKOH AND THE COMPTON GAMMA-RAY OBSERVATORY SO ASTROPHYSICAL JOURNAL LA English DT Article DE MHD; SUN, FLARES; SUN, X-RAYS, GAMMA RAYS ID SOFT-X-RAY; BRAGG CRYSTAL SPECTROMETER; XIX RESONANCE LINE; RUNAWAY ELECTRONS; ACCELERATION; EMISSION AB We apply a DC-electric field model to the analysis of soft and hard X-ray observations of a solar flare observed by Yohkoh and the Compton Gamma-Ray Observatory CGRO on 1992 September 6. The flare was observed simultaneously in the soft X-ray Ca XIX line by the Yokhoh Bragg Crystal Spectrometer (BCS) and in hard X-rays (>50 keV) by the CGRO Burst and Transient Spectrometer Experiment (BATSE). A strong stationary component of Ca XIX emission was present at the start of impulsive hard X-ray emission indicating an extended phase of heating prior to the production of energetic nonthermal electrons. We interpret the preflare Ca xrx emission as a signature of Joule heating by field-aligned currents. We relate the temporal variation of impulsive hard X-ray emission to the rate of runaway electron acceleration by the DC-electric field associated with the current. We find that the initial rise in hard X-ray emission is consistent with electron acceleration by a DC-electric field that increased from a preflare value of less than or similar to 10(-5) V cm(-1) to similar or equal to(9 +/- 1) x 10(-5) V cm(-1) at the time of the first hard X-ray peak and then remained constant during the rest of the impulsive phase. We attribute the increase in electric field strength to the formation of a current sheet at the reconnection point of two loop structures. The decrease in hard X-ray emission after flare maximum is consistent with a reduction in the number of runaway electrons due to an increase in coronal density produced by chromospheric evaporation. The increased density quenches the runaway process by enhancing collisional thermalization of electrons. To avoid the generation of an unrealistically large magnetic field, the flaring region must be highly filamented into greater than or similar to 10(6) oppositely directed current channels of similar to 30 cm width with an initial preflare current of similar or equal to 3 x 10(10) A per channel. C1 USN, RES LAB, WASHINGTON, DC 20375 USA. NASA, GODDARD SPACE FLIGHT CTR, ASTRON & SOLAR PHYS LAB, GREENBELT, MD 20771 USA. RP ZARRO, DM (reprint author), NASA, GODDARD SPACE FLIGHT CTR, APPL RES CORP, CTR SOLAR DATA ANAL, CODE 682, GREENBELT, MD 20771 USA. RI Dennis, Brian/C-9511-2012 NR 33 TC 13 Z9 13 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 1995 VL 440 IS 2 BP 888 EP 893 DI 10.1086/175327 PN 1 PG 6 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG505 UT WOS:A1995QG50500043 ER PT J AU FONTENLA, JM AMBASTHA, A KALMAN, B CSEPURA, G AF FONTENLA, JM AMBASTHA, A KALMAN, B CSEPURA, G TI THE MAGNETIC EVOLUTION OF AR-6555 WHICH LED TO 2 IMPULSIVE, RELATIVELY COMPACT, X-TYPE FLARES SO ASTROPHYSICAL JOURNAL LA English DT Article DE SUN, FLARES; SUN, MAGNETIC FIELDS; SUN, X-RAYS, GAMMA RAYS ID ELECTRIC CURRENTS; ACTIVE REGIONS; FIELDS; MORPHOLOGY AB We study the evolution of the vector magnetic field and the sunspot motions observed in AR 6555 during 1991 March 23-26. This region displays two locations of large magnetic shear that were also sites of flare activity. The first location produced two large (X-class) flares during the period covered by our observations. The second location had larger magnetic shear than the first but produced only small (M- and C-class) flares during our observations. We study the evolution of the photospheric magnetic field in relation to the large flares in the first location. These flares occurred around the same included polarity and have very similar characteristics (soft X-ray light curves, energies, etc.). However, the whole active region has changed substantially in the period between them. We found several characteristics of the region that appear related to the occurrence of these hares: (1) The flares occurred near regions of large magnetic ''shear,'' but not at the locations of maximum shear or maximum field. (2) Potential field extrapolations of the observed field suggest that the topology changed, prior to the first of the two flares, in such a way that a null appeared in the coarse magnetic field. (3) This null was located close to both X-class flares and remained in that location for a few days while the two flares were observed. (4) The flaring region has a pattern of vector field and sunspot motions in which material is ''squeezed'' along the polarity inversion line. This pattern is very different from that usually associated with shearing arcades, but it is similar to that suggested previously by Fontenla and Davis. The vertical electric currents, inferred from the transverse field, are consistent with this pattern. (5) A major reconfiguration of the longitudinal field and the vertical electric currents occurred just prior to the first of the two flares. Both changes imply substantial variations of the magnetic structure of the region. On the basis of the available data we suggest that these changes made the flaring possible, and we develop a scenario that can explain the origin of the magnetic free-energy that was released in these flares. C1 UNIV ALABAMA,CTR SPACE PLASMA & AERON RES,HUNTSVILLE,AL 35899. HUNGARIAN ACAD SCI,HELIPHYS OBSERV,H-4010 DEBRECEN,HUNGARY. NASA,GEORGE C MARSHALL SPACE FLIGHT CTR,SPACE SCI LAB,NRC,NATL ACAD SCI,HUNTSVILLE,AL 35812. NR 26 TC 20 Z9 20 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 1995 VL 440 IS 2 BP 894 EP 906 DI 10.1086/175328 PN 1 PG 13 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG505 UT WOS:A1995QG50500044 ER PT J AU BARING, MG AF BARING, MG TI PHOTON-SPLITTING LIMITS TO THE HARDNESS OF EMISSION IN STRONGLY MAGNETIZED SOFT GAMMA-REPEATERS SO ASTROPHYSICAL JOURNAL LA English DT Article DE GAMMA RAYS, BURSTS; GAMMA RAYS, THEORY; MAGNETIC FIELDS; POLARIZATION; RADIATION MECHANISMS, NONTHERMAL; STARS, NEUTRON ID RAY BURSTS; FIELDS AB Soft gamma repeaters are characterized by recurrent activity consisting of short-duration outbursts of high-energy emission that is typically of temperature less than 40 keV. One recent model of repeaters is that they originate in the environs of neutron stars with superstrong magnetic fields, perhaps greater than 10(14) G. In such fields, the exotic process of magnetic photon splitting gamma --> gamma gamma acts very effectively to reprocess gamma-ray radiation down to hard X-ray energies. In this Letter, the action of photon splitting is considered in some detail, via the solution of photon kinetic equations, determining how it limits the hardness of emission in strongly magnetized repeaters, and thereby obtaining observational constraints to the field in SGR 1806-20. RP BARING, MG (reprint author), NASA,GODDARD SPACE FLIGHT CTR,CODE 665,GREENBELT,MD 20771, USA. NR 18 TC 25 Z9 25 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 1995 VL 440 IS 2 BP L69 EP L72 DI 10.1086/187763 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG508 UT WOS:A1995QG50800010 ER PT J AU CHEN, W GEHRELS, N DIEHL, R AF CHEN, W GEHRELS, N DIEHL, R TI UNDERSTANDING COMPTEL AL-26 1.8-MEV MAP FEATURES SO ASTROPHYSICAL JOURNAL LA English DT Article DE GALAXY, CENTER; GALAXY, STRUCTURE; GAMMA RAYS, THEORY ID GALACTIC-CENTER; MASSIVE STARS AB The COMPTEL sky map of the 1.8 MeV line emission from Al-26 shows an extended diffuse distribution along the Galactic plane with a peculiar large scale asymmetry about the Galactic center (GC) and a clumpy structure with several noticeable hot spots. The most prominent hot spot at the GC appears shifted to positive longitude by about 2 degrees. Nearby supernova remnants or Wolf-Rayet stars are plausible explanations for individual hot spots such as in the Vela region. We show that the global asymmetry and most hot spots can be understood by a more general model: the Al-26 sources are confined in the spiral arms of our Galaxy, and coagent star formation is responsible for additional clumpiness. The off-centered GC hot spot is probably due to the observed asymmetrically distributed circumnuclear molecular gas interacting with a central stellar bar, whose existence has been inferred from IR observations. C1 NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. MAX PLANCK INST EXTRATERR PHYS,D-85740 GARCHING,GERMANY. RI Gehrels, Neil/D-2971-2012 NR 24 TC 12 Z9 13 U1 0 U2 0 PU UNIV CHICAGO PRESS PI CHICAGO PA 5720 S WOODLAWN AVE, CHICAGO, IL 60637 SN 0004-637X J9 ASTROPHYS J JI Astrophys. J. PD FEB 20 PY 1995 VL 440 IS 2 BP L57 EP L60 DI 10.1086/187760 PN 2 PG 4 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG508 UT WOS:A1995QG50800007 ER PT J AU DODELSON, S KOSOWSKY, A MYERS, ST AF DODELSON, S KOSOWSKY, A MYERS, ST TI NOISE CORRELATIONS IN COSMIC MICROWAVE BACKGROUND EXPERIMENTS SO ASTROPHYSICAL JOURNAL LA English DT Article DE COSMIC MICROWAVE BACKGROUND; METHODS, DATA ANALYSIS AB Many analyses of microwave background experiments neglect the correlation of noise in different frequency or polarization channels. We show that these correlations, should they be present, can lead to severe misinterpretation of an experiment. In particular, correlated noise arising from either electronics or atmosphere may mimic a cosmic signal. We quantify how the likelihood function for a given experiment varies with noise correlation, using both simple analytic models and actual data. For a typical microwave background anisotropy experiment, noise correlations at the level of 1% of the overall noise can seriously reduce the significance of a given detection. C1 UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. CALTECH,DIV PHYS MATH & ASTRON,PASADENA,CA 91125. RP DODELSON, S (reprint author), FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,POB 500,BATAVIA,IL 60510, USA. NR 6 TC 2 Z9 2 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 1995 VL 440 IS 2 BP L37 EP L39 DI 10.1086/187755 PN 2 PG 3 WC Astronomy & Astrophysics SC Astronomy & Astrophysics GA QG508 UT WOS:A1995QG50800002 ER PT J AU WILLETT, JC LEVINE, DM IDONE, VP AF WILLETT, JC LEVINE, DM IDONE, VP TI LIGHTNING-CHANNEL MORPHOLOGY REVEALED BY RETURN-STROKE RADIATION-FIELD WAVE-FORMS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID TRANSMISSION-LINE MODEL; ELECTROMAGNETIC-RADIATION; FLASHES; LEADERS; SPECTRA AB Simultaneous video and wideband electric field recordings of 32 cloud-to-ground lightning flashes in Florida were analyzed to show that the formation of new channels to ground can be detected by examination of the return-stroke radiation fields alone. The return-stroke E and dE/dt waveforms were subjectively classified according to their fine structure. Then the video images were examined field by field to identify each waveform with a visible channel to ground. Fifty-five correlated waveforms and channel images were obtained. Of these, all 34 first-stroke waveforms (multiple jagged E peaks, noisy dE/dt), 8 of which were not radiated by the chronologically first stroke in the hash, came from new channels to ground (not previously seen on video). Ah 18 subsequent-stroke waveforms (smoothly rounded E and quiet dE/dt after the initial peak) were radiated by old channels (illuminated by a previous stroke). Two double-ground waveforms (two distinct first-return-stroke pulses separated by tens of microseconds or less) coincided with video fields showing two new channels. One ''anomalous-stroke'' waveform (beginning like a first stroke and ending like a subsequent) was produced by a new channel segment to ground branching off an old channel. This waveform classification depends on the presence or absence of high-frequency fine structure. Fourier analysis shows that first-stroke waveforms contain about 18 dB more spectral power in the frequency interval from 500 kHz to at least 7 MHz than subsequent-stroke waveforms for at least 13 mu s after the main peak. C1 NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. SUNY ALBANY, DEPT ATMOSPHER SCI, ALBANY, NY 12222 USA. RP WILLETT, JC (reprint author), PHILLIPS LAB, GEOPHYS DIRECTORATE, BEDFORD, MA 01731 USA. NR 35 TC 26 Z9 28 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 FEB 20 PY 1995 VL 100 IS D2 BP 2727 EP 2738 DI 10.1029/94JD03123 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000002 ER PT J AU MANNEY, GL FROIDEVAUX, L WATERS, JW ZUREK, RW AF MANNEY, GL FROIDEVAUX, L WATERS, JW ZUREK, RW TI EVOLUTION OF MICROWAVE LIMB SOUNDER OZONE AND THE POLAR VORTEX DURING WINTER SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ATMOSPHERE RESEARCH SATELLITE; POTENTIAL VORTICITY; MLS OBSERVATIONS; GLOBAL OZONE; SOUTHERN; TRANSPORT; STRATOSPHERE; WAVES; MODEL; O3 AB The evolution of polar ozone observed by the Upper Atmosphere Research Satellite Microwave Limb Sounder is described for the northern hemisphere (NH) winters of 1991/1992, 1992/1993, and 1993/1994 and the southern hemisphere (SH) winters of 1992 and 1993. Interannual and interhemispheric variability in polar ozone evolution are closely related to differences in the polar vortex and to the frequency, duration and strength of stratospheric sudden warmings. Ozone in the midstratospheric vortices increases during the winter, with largest increases associated with stratospheric warmings and a much larger increase in the NH than in the SH. A smaller NH increase was observed in 1993/1994, when the middle stratospheric vortex was stronger. During strong stratospheric warmings in the NH, the upper stratospheric vortex may be so much eroded that it presents little barrier to poleward transport; in contrast, the SH vortex remains strong throughout the stratosphere during wintertime warmings, and ozone increases only below the mixing ratio peak, due to enhanced diabatic descent. Ozone mixing ratios decrease rapidly in the lower stratosphere in both SH late winters, as expected from chemical destruction due to enhanced reactive chlorine. The interplay between dynamics and chemistry is more complex in the NH lower stratosphere and interannual variability is greater. Evidence has previously been shown for chemical ozone destruction in the 1991/1992 and 1992/1993 winters. We show here evidence suggesting some chemical destruction in late February and early March 1994. In the NH late winter lower stratosphere the pattern of high-ozone values (typical of the vortex) seen in mid-latitudes is related to the strength of the lower-stratospheric vortex, with the largest areal extent of high ozone outside the vortex in 1994, when the lower stratospheric vortex is relatively weak, and the least extent in 1993 when the lower stratospheric vortex is strongest. RP MANNEY, GL (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, MAIL STOP 183-701, PASADENA, CA 91109 USA. NR 35 TC 33 Z9 33 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 1995 VL 100 IS D2 BP 2953 EP 2972 DI 10.1029/94JD02823 PG 20 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000017 ER PT J AU HERMAN, JR NEWMAN, PA MCPETERS, R KRUEGER, AJ BHARTIA, PK SEFTOR, CJ TORRES, O JAROSS, G CEBULA, RP LARKO, D WELLEMEYER, C AF HERMAN, JR NEWMAN, PA MCPETERS, R KRUEGER, AJ BHARTIA, PK SEFTOR, CJ TORRES, O JAROSS, G CEBULA, RP LARKO, D WELLEMEYER, C TI METEOR-3 TOTAL OZONE MAPPING SPECTROMETER OBSERVATIONS OF THE 1993 OZONE HOLE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE; TOMS OBSERVATIONS; DEPLETION AB The development of the springtime (September-November) Antarctic ozone hole was observed by the Meteor 3/total ozone mapping spectrometer (TOMS) to result in the lowest ozone value, 85 DU (Dobson units) on October 8, 1993, ever measured by TOMS. During late September and early October the region of extremely low ozone values was centered on the geographical pole between 85 degrees S and 90 degrees S. The geographical extent of the ozone hole region, the area within the 220-DU contour, reached a maximum during the first week in October at a near-circular area covering 24 x 10(6) km(2) reaching to the southern tip of South America. This approximately matched the 1992 area record, After the maximum area was reached in early October, the 1993 ozone hole region was significantly larger than during 1992 throughout the remainder of the month of October. The very low ozone values over the Antarctic continent have been confirmed by independent ground-based data. Unlike 1992, the formation of the 1993 Antarctic ozone hole does not coincide with unusually low ozone values observed over most of the globe for the past 2 years. The most recent ozone data from Meteor 3/TOMS show that there has been a recovery at all latitudes from the extraordinarily low values observed during 1992 and part of 1993 after the June 1991 eruption of Mount Pinatubo. Meteor 3/TOMS is described and compared with Nimbus 7/TOMS during the 1991 to May 1993 overlap period. Observations of the 1992 ozone hole are presented from both instruments and are shown to agree within 5 DU. RP HERMAN, JR (reprint author), NASA, GODDARD SPACE FLIGHT CTR, MAIL STOP 916, GREENBELT, MD 20771 USA. RI Newman, Paul/D-6208-2012; McPeters, Richard/G-4955-2013; Torres, Omar/G-4929-2013; OI Newman, Paul/0000-0003-1139-2508; McPeters, Richard/0000-0002-8926-8462; Herman, Jay/0000-0002-9146-1632 NR 26 TC 17 Z9 17 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 1995 VL 100 IS D2 BP 2973 EP 2983 DI 10.1029/94JD02316 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000018 ER PT J AU JAROSS, G KRUEGER, A CEBULA, RP SEFTOR, C HARTMANN, U HARING, R BURCHFIELD, D AF JAROSS, G KRUEGER, A CEBULA, RP SEFTOR, C HARTMANN, U HARING, R BURCHFIELD, D TI CALIBRATION AND POSTLAUNCH PERFORMANCE OF THE METEOR 3/TOMS INSTRUMENT SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ULTRAVIOLET AB Prelaunch and postlaunch calibration results for the Meteor 3/TOMS instrument are presented here. The instrument, launched aboard a Russian spacecraft in 1991, is the second in a series of total ozone mapping spectrometer (TOMS) instruments designed to provide daily global mapping of ozone overburden. Ozone amounts are retrieved from measurements of Earth albedo in the 312- to 380-nm range. The accuracy of albedo measurements is primarily tied to knowledge of the reflective properties of diffusers used in the calibrations and to the instrument's wavelength selection. These and other important prelaunch calibrations are presented. Their estimated accuracies are within the bounds necessary to determine column ozone to better than 1%. However, postlaunch validation results indicate some prelaunch calibration uncertainties may be larger than originally estimated. Instrument calibrations have been maintained postlaunch to within a corresponding 1% error in retrieved ozone. Onboard calibrations, including wavelength monitoring and a three-diffuser solar measurement system, are described and specific results are presented. Other issues, such as the effects of orbital precession on calibration and recent chopper wheel malfunctions, are also discussed. C1 ORBITAL SCI CORP, POMONA, CA 91767 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. RP JAROSS, G (reprint author), HUGHES STX CORP, 7701 GREENBELT RD, GREENBELT, MD 20770 USA. NR 20 TC 25 Z9 26 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 1995 VL 100 IS D2 BP 2985 EP 2995 DI 10.1029/94JD02317 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000019 ER PT J AU BHARTIA, PK TAYLOR, S MCPETERS, RD WELLEMEYER, C AF BHARTIA, PK TAYLOR, S MCPETERS, RD WELLEMEYER, C TI APPLICATION OF THE LANGLEY PLOT METHOD TO THE CALIBRATION OF THE SOLAR BACKSCATTERED ULTRAVIOLET INSTRUMENT ON THE NIMBUS-7 SATELLITE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DOBSON AB The concept of the well-known Langley plot technique, used for the calibration of ground-based instruments, has been generalized for application to satellite instruments. In polar regions, near summer solstice, the solar backscattered ultraviolet (SBUV) instrument on the Nimbus 7 satellite samples the same ozone field at widely different solar zenith angles. These measurements are compared to assess the long-term drift in the instrument calibration. Although the technique provides only a relative wavelength-to-wavelength calibration, it can be combined with existing techniques to determine the drift of the instrument at any wavelength. Using this technique, we have generated a 12-year data set of ozone vertical profiles from SBUV with an estimated accuracy of +/-5% at 1 mbar and +/-2% at 10 mbar (95% confidence) over 12 years. Since the method is insensitive to true changes in the atmospheric ozone profile, it can also be used to compare the calibrations of similar SBUV instruments launched without temporal overlap. C1 HUGHES STX CORP, LANHAM, MD 20706 USA. RP BHARTIA, PK (reprint author), NASA, GODDARD SPACE FLIGHT CTR, MAIL CODE 916, GREENBELT, MD 20771 USA. RI McPeters, Richard/G-4955-2013; Bhartia, Pawan/A-4209-2016 OI McPeters, Richard/0000-0002-8926-8462; Bhartia, Pawan/0000-0001-8307-9137 NR 11 TC 19 Z9 19 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 1995 VL 100 IS D2 BP 2997 EP 3004 DI 10.1029/94JD03072 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000020 ER PT J AU TSOU, JJ CONNOR, BJ PARRISH, A MCDERMID, IS CHU, WP AF TSOU, JJ CONNOR, BJ PARRISH, A MCDERMID, IS CHU, WP TI GROUND-BASED MICROWAVE MONITORING OF MIDDLE ATMOSPHERE OZONE - COMPARISON TO LIDAR AND STRATOSPHERIC AND GAS EXPERIMENT-II SATELLITE-OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID DIURNAL-VARIATIONS; PROFILES; TEMPERATURE; ANTARCTICA; RADIOMETRY AB A dedicated ground-based microwave radiometer was in operation to monitor the middle atmospheric ozone concentration at Table Mountain Facility (TMF) of the Jet Propulsion Laboratory (JPL), California (34.4 degrees N, 117.7 degrees W) from July 1989 to June 1992, as a part of the Network for Detection of Stratospheric Change. Ozone profiles from 56 to 0.04 mbar (similar to 20-70 km) were retrieved from the microwave data. The focus in this paper is to validate the microwave ozone observations from 56 to 1 mbar by comparing the results from a JPL ground-based lidar located at the same site and from the Stratospheric Aerosol and Gas Experiment II (SAGE II) satellite overpasses within 1000 km of TMF and to examine the ability of these instruments to detect short-term, seasonal, and annual variations in ozone. The profile comparison results show that the mean differences of microwave ozone from lidar and SAGE II are about 5% or less and the root-mean-square scatter about the mean is mainly from the precision of the instruments. A correlation analysis of ozone time series suggests highly significant correlations up to 2.4 mbar between lidar and microwave measurements and up to 1 mbar between SAGE II and microwave. The short-term and seasonal variation of the ozone profile seen in the microwave measurements is shown to be consistent with the observations of lidar and SAGE II, and the interannual variation of ozone appears to be detectable within an accuracy of a few percent with the microwave instrument. C1 JET PROPULS LAB, WRIGHTWOOD, CA 92397 USA. UNIV MASSACHUSETTS, DEPT PHYS & ASTRON, AMHERST, MA 01003 USA. LOCKHEED ENGN & SCI CO, HAMPTON, VA 23666 USA. MILLITECH CORP, DEERFIELD, MA USA. RP TSOU, JJ (reprint author), NASA, LANGLEY RES CTR, MS 401B, 21 LANGLEY BLVD, BLDG 1250, HAMPTON, VA 23681 USA. NR 30 TC 33 Z9 34 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 1995 VL 100 IS D2 BP 3005 EP 3016 DI 10.1029/94JD02947 PG 12 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000021 ER PT J AU WOODBRIDGE, EL ELKINS, JW FAHEY, DW HEIDT, LE SOLOMON, S BARING, TJ GILPIN, TM POLLOCK, WH SCHAUFFLER, SM ATLAS, EL LOEWENSTEIN, M PODOLSKE, JR WEBSTER, CR MAY, RD GILLIGAN, JM MONTZKA, SA BOERING, KA SALAWITCH, RJ AF WOODBRIDGE, EL ELKINS, JW FAHEY, DW HEIDT, LE SOLOMON, S BARING, TJ GILPIN, TM POLLOCK, WH SCHAUFFLER, SM ATLAS, EL LOEWENSTEIN, M PODOLSKE, JR WEBSTER, CR MAY, RD GILLIGAN, JM MONTZKA, SA BOERING, KA SALAWITCH, RJ TI ESTIMATES OF TOTAL ORGANIC AND INORGANIC CHLORINE IN THE LOWER STRATOSPHERE FROM IN-SITU AND FLASK MEASUREMENTS DURING AASE-II SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE ATMOSPHERE; ANTARCTIC VORTEX; OZONE DEPLETION; GROWTH-RATES; WINTER; RADICALS; DECREASE; AGE; AIR AB Aircraft sampling has provided extensive in situ and flask measurements of organic chlorine species in the lower stratosphere. The recent Airborne Arctic Stratospheric Expedition II (AASE II) included two independent measurements of organic chlorine species using whole air sample and real-time techniques. From the whole air sample measurements we derive directly the burden of total organic chlorine (CCly) in the fewer stratosphere. From the more limited real-time measurements we estimate the CCly burden using mixing ratios and growth rates of the principal CCly species in the troposphere in conjunction with results from a two-dimensional photochemical model. Since stratospheric chlorine is tropospheric in origin and tropospheric mixing ratios are increasing, it is necessary to establish the average age of a stratospheric air parcel to assess its total chlorine (Cl-Total) abundance. Total inorganic chlorine (Cl-y) in the parcel is then estimated by the simple difference, Cl-y = Cl-Total - CCly. The consistency of the results from these two quite different techniques suggests that we can determine the CCly and Cl-y in the lower stratosphere with confidence. Such estimates of organic and inorganic chlorine are crucial in evaluating the photochemistry controlling chlorine partitioning and hence ozone loss processes in the lower stratosphere. C1 NATL CTR ATMOSPHER RES, BOULDER, CO 80307 USA. UNIV COLORADO, CIRES, BOULDER, CO 80309 USA. HARVARD UNIV, DEPT EARTH & PLANETARY SCI, CAMBRIDGE, MA 02138 USA. NOAA, CLIMATE MONITORING & DIAGNOST LAB, BOULDER, CO 80303 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. RP WOODBRIDGE, EL (reprint author), NOAA, AERON LAB, 325 BROADWAY, R-E-AL6, BOULDER, CO 80303 USA. RI Salawitch, Ross/B-4605-2009; Gilligan, Jonathan/I-8938-2014; Atlas, Elliot/J-8171-2015; Fahey, David/G-4499-2013 OI Salawitch, Ross/0000-0001-8597-5832; Gilligan, Jonathan/0000-0003-1375-6686; Fahey, David/0000-0003-1720-0634 NR 39 TC 91 Z9 91 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 1995 VL 100 IS D2 BP 3057 EP 3064 DI 10.1029/94JD02744 PG 8 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000026 ER PT J AU FAHEY, DW KEIM, ER WOODBRIDGE, EL GAO, RS BOERING, KA DAUBE, BC WOFSY, SC LOHMANN, RP HINTSA, EJ DESSLER, AE WEBSTER, CR MAY, RD BROCK, CA WILSON, JC MIAKELYE, RC BROWN, RC RODRIGUEZ, JM LOEWENSTEIN, M PROFFITT, MH STIMPFLE, RM BOWEN, SW CHAN, KR AF FAHEY, DW KEIM, ER WOODBRIDGE, EL GAO, RS BOERING, KA DAUBE, BC WOFSY, SC LOHMANN, RP HINTSA, EJ DESSLER, AE WEBSTER, CR MAY, RD BROCK, CA WILSON, JC MIAKELYE, RC BROWN, RC RODRIGUEZ, JM LOEWENSTEIN, M PROFFITT, MH STIMPFLE, RM BOWEN, SW CHAN, KR TI IN-SITU OBSERVATIONS IN AIRCRAFT EXHAUST PLUMES IN THE LOWER STRATOSPHERE AT MIDLATITUDES SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID ANTARCTIC OZONE EXPERIMENT; CIVIL TRANSPORT AIRCRAFT; KINETIC DATA-BASE; TROPOSPHERIC OZONE; REACTIVE NITROGEN; ER-2 AIRCRAFT; EMISSIONS; CHEMISTRY; CLOUD; COMBUSTION AB Instrumentation on the NASA ER-2 high-altitude aircraft has been used to observe engine exhaust from the same aircraft while operating in the lower stratosphere. Encounters with the exhaust plume occurred approximately 10 min after emission with spatial scales near 2 km and durations of up to 10 s. Measurements include total reactive nitrogen, NOy, the component species NO and NO2, CO2, H2O, CO, N2O, condensation nuclei, and meteorological parameters. The integrated amounts of CO2 and H2O during the encounters are consistent with the stoichiometry of fuel combustion (1:1 molar). Emission indices (EI) for NOx (= NO + NO2), CO, and N2O are calculated using simultaneous measurements of CO2. EI values for NOX near 4 g (kg fuel)(-1) are in good agreement with values scaled from limited ground-based tests of the ER-2 engine. Non-NOx species comprise less than about 20% of emitted reactive nitrogen, consistent with model evaluations. In addition to demonstrating the feasibility of aircraft plume detection, these results increase confidence in the projection of emissions from current and proposed supersonic aircraft fleets and hence in the assessment of potential long-term changes in the atmosphere. C1 HARVARD UNIV, DEPT EARTH & PLANETARY SCI, CAMBRIDGE, MA 02138 USA. NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. UNIV DENVER, DEPT ENGN, DENVER, CO 80208 USA. AERODYNE RES INC, BILLERICA, MA 01821 USA. HARVARD UNIV, DEPT CHEM, CAMBRIDGE, MA 02138 USA. NASA, GODDARD SPACE FLIGHT CTR, GREENBELT, MD 20771 USA. PRATT & WHITNEY, E HARTFORD, CT 06108 USA. CALTECH, JET PROP LAB, PASADENA, CA 91109 USA. ATMOSPHER & ENVIRONM RES INC, CAMBRIDGE, MA 02139 USA. RP FAHEY, DW (reprint author), NOAA, AERON LAB, 325 BROADWAY, R-E-AL6, BOULDER, CO 80303 USA. RI Brock, Charles/G-3406-2011; Rodriguez, Jose/G-3751-2013; Gao, Ru-Shan/H-7455-2013; Fahey, David/G-4499-2013; Dessler, Andrew/G-8852-2012 OI Brock, Charles/0000-0002-4033-4668; Rodriguez, Jose/0000-0002-1902-4649; Fahey, David/0000-0003-1720-0634; Dessler, Andrew/0000-0003-3939-4820 NR 41 TC 68 Z9 68 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 1995 VL 100 IS D2 BP 3065 EP 3074 DI 10.1029/94JD02298 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000027 ER PT J AU CONSIDINE, DB DOUGLASS, AR JACKMAN, CH AF CONSIDINE, DB DOUGLASS, AR JACKMAN, CH TI SENSITIVITY OF 2-DIMENSIONAL MODEL PREDICTIONS OF OZONE RESPONSE TO STRATOSPHERIC AIRCRAFT - AN UPDATE SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID CIVIL TRANSPORT AIRCRAFT; HETEROGENEOUS CHEMISTRY; IMPACT; NOX AB The Goddard Space Flight Center two-dimensional model of stratospheric photochemistry and dynamics has been used to calculate the O-3 response to stratospheric aircraft (high-speed civil transport (HSCT)) emissions. The sensitivity of the model O-3 response was examined for systematic variations of five parameters and two reaction rates over a wide range, expanding on calculations by various modeling groups for the NASA High Speed Research Program and the World Meteorological Organization. In all, 448 model runs were required to test the effects of variations in the latitude, altitude, and magnitude of the aircraft emissions perturbation, the background chlorine levels, the background sulfate aerosol surface area densities, and the rates of two key reactions. No deviation from previous conclusions concerning the response of O-3 to HSCTs was found in this more exhaustive exploration of parameter space. Maximum O-3 depletions occur far high-altitude, low-latitude HSCT perturbations. Small increases in global total O-3 can occur for low-altitude, high-latitude injections. Decreasing aerosol surface area densities and background chlorine levels increases the sensitivity of model O-3 to the HSCT perturbations. The location of the aircraft emissions is the most important determinant of the model response. Response to the location of the HSCT emissions is not changed qualitatively by changes in background chlorine and aerosol loading. The response is also not very sensitive to changes in the rates of the reactions NO + HO2 --> NO2 + OH and HO2 + O-3 --> OH + 2O(2) over the limits of their respective uncertainties. Finally, levels of lower stratospheric HOx generally decrease when the HSCT perturbation is included, even though there are large increases in H2O due to the perturbation. RP CONSIDINE, DB (reprint author), NASA, GODDARD SPACE FLIGHT CTR, CODE 916, GREENBELT, MD 20771 USA. RI Douglass, Anne/D-4655-2012; Jackman, Charles/D-4699-2012 NR 30 TC 6 Z9 6 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 20 PY 1995 VL 100 IS D2 BP 3075 EP 3090 DI 10.1029/94JD02751 PG 16 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000028 ER PT J AU STILLER, GP GUNSON, MR LOWES, LL ABRAMS, MC RAPER, OF FARMER, CB ZANDER, R RINSLAND, CP AF STILLER, GP GUNSON, MR LOWES, LL ABRAMS, MC RAPER, OF FARMER, CB ZANDER, R RINSLAND, CP TI STRATOSPHERIC AND MESOSPHERIC PRESSURE-TEMPERATURE PROFILES FROM ROTATIONAL ANALYSIS OF CO2 LINES IN ATMOSPHERIC TRACE MOLECULE SPECTROSCOPY ATLAS-1 INFRARED SOLAR OCCULTATION SPECTRA SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID MIDDLE AB A simple, classical, and expedient method for the retrieval of atmospheric pressure-temperature profiles has been applied to the high-resolution infrared solar absorption spectra obtained with the atmospheric trace molecule spectroscopy (ATMOS) instrument. The basis for this method is a rotational analysis of retrieved apparent abundances from CO2 rovibrational absorption lines, employing existing constituent concentration retrieval software used in the analysis of data returned by ATMOS. Pressure-temperature profiles derived from spectra acquired during the ATLAS 1 space shuttle mission of March-April 1992 are quantitatively evaluated and compared with climatological and meteorological data as a means of assessing the validity of this approach. C1 UNIV KARLSRUHE, KARLSRUHE, GERMANY. UNIV LIEGE, INST ASTROPHYS, B-4000 LIEGE, BELGIUM. CALTECH, JET PROP LAB, PASADENA, CA 91125 USA. NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. RP STILLER, GP (reprint author), KERNFORSCHUNGSZENTRUM KARLSRUHE GMBH, INST METEOROL & KLIMAFORSCH, KARLSRUHE, GERMANY. RI Stiller, Gabriele/A-7340-2013 OI Stiller, Gabriele/0000-0003-2883-6873 NR 19 TC 27 Z9 27 U1 0 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 20 PY 1995 VL 100 IS D2 BP 3107 EP 3117 DI 10.1029/94JD03105 PG 11 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000030 ER PT J AU MENZIES, RT TRATT, DM AF MENZIES, RT TRATT, DM TI EVIDENCE OF SEASONALLY DEPENDENT STRATOSPHERE TROPOSPHERE EXCHANGE AND PURGING OF LOWER STRATOSPHERIC AEROSOL FROM A MULTIYEAR LIDAR DATA SET SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID BACKSCATTER MEASUREMENTS; INSITU MEASUREMENTS; VOLCANIC AEROSOLS; PINATUBO AEROSOL; TROPOPAUSE FOLDS; DOWNWARD CONTROL; MASS; OZONE; CONSTITUENTS; WAVELENGTHS AB Tropospheric and lower stratospheric aerosol backscatter data obtained from a calibrated backscatter lidar at Pasadena, California (34 degrees N latitude) over the 1984-1993 period clearly indicate tightly coupled aerosol optical properties in the upper troposphere and lower stratosphere in the winter and early spring, due to the active midlatitude stratospheric-tropospheric (ST) exchange processes occurring at this time of year. Lidar data indicate that during pre-Pinatubo background conditions, the subsequent purging of the aerosol in the upper troposphere caused a significant reduction in the aerosol content throughout the 8-18 km altitude region in the early spring period. The post-Pinatubo evidence of intense exchange in the winter and early spring is a significant increase in the upper tropospheric aerosol content, such that the backscatter levels reach values nearly equivalent to the enhanced backscatter levels existing in the lower stratosphere. The calculated stratospheric mass extrusion rate is consistent with a 45-day lifetime of lower stratospheric aerosol during this part of the year, which implies that midlatitude ST exchange is a significant sink for stratospheric aerosol. RP MENZIES, RT (reprint author), CALTECH, JET PROP LAB, 4800 OAK GROVE DR, PASADENA, CA 91109 USA. RI Tratt, David/A-7884-2009 OI Tratt, David/0000-0002-3942-6848 NR 45 TC 18 Z9 18 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 1995 VL 100 IS D2 BP 3139 EP 3148 DI 10.1029/94JD02848 PG 10 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000033 ER PT J AU WANG, PH MINNIS, P YUE, GK AF WANG, PH MINNIS, P YUE, GK TI EXTINCTION COEFFICIENT (1-MU-M) PROPERTIES OF HIGH-ALTITUDE CLOUDS FROM SOLAR OCCULTATION MEASUREMENTS (1985-1990) - EVIDENCE OF VOLCANIC AEROSOL EFFECT SO JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES LA English DT Article ID POLAR STRATOSPHERIC CLOUDS; MOUNT-PINATUBO ERUPTION; CIRRUS CLOUD; EL-CHICHON; RADIATIVE PROPERTIES; SIZE DISTRIBUTION; II MEASUREMENTS; SAM-II; SAGE; CLIMATE AB The properties of the 1-mu m volume extinction coefficient of two geographically different high-altitude cloud systems have been examined for the posteruption period (1985-1990) of the April 1982 El Chichon volcanic event with emphasis on the effect of volcanic aerosols on clouds. These two high-altitude cloud systems are the tropical clouds in the tropopause region observed by the Stratospheric Aerosol and Gas Experiment (SAGE) II and the polar stratospheric clouds (PSCs) sighted by the Stratospheric Aerosol Measurement (SAM) II. The results indicate that volcanic aerosols alter the frequency distributions of these high-altitude clouds in such a manner that the occurrence of clouds having high extinction coefficients (6x10(-3) - 2x10(-2) km(-1)) is suppressed, while that of clouds having low extinction coefficients (2x10(-3) - 6x10(-2) km(-1)) is enhanced. This influence of the volcanic aerosols appears to be opposite to the increase in the extinction coefficient of optically thick clouds observed by the faith Radiation Budget Experiment (ERBE) during the initial posteruption period of the June 1991 Pinatubo eruption. A plausible explanation of this difference, based on the Mie theory, is presented. The Mie calculation indicates that there are two possible types of response of cloud extinction coefficient to changes in aerosol concentration depending on the primary effective radius (r(e)) of cloud systems observed by the instrument. These two types of response are separated by the cloud particle effective radius of about 0.8 mu m. When r(e) is smaller than 0.8 mu m, the cloud extinction coefficient decreases in response to increases of aerosol concentration, and when r(e) is greater than 0.8 mu m, the opposite happens. As a consequence, the effective radius of most, if not all, of the high-altitude clouds, measured by the SAGE series of satellite instruments must be less than about 0.8 mu m. This mean cloud particle size implied by the satellite extinction-coefficient data at a single wavelength (1 mu m) is further substantiated by the particle size analysis based on cloud extinction coefficient at two wavelengths (0.525 and 1.02 mu m) obtained by the SAGE II observations. Most of the radiation measured by ERBE is reflected by cloud systems comprised of particles having effective radii much greater than 1 mu m. A reduction in the effective radius of these clouds due to volcanic aerosols is expected to increase their extinction-coefficient values, opposite the effect observed by SAGE II and SAM II. This work further illustrates the capability of the solar occultation satellite sensor to provide particulate extinction-coefficient measurements important to the study of the aerosol-cloud interactions. Finally, the June 1991 Mount Pinatubo major eruption put 3 times more material into the stratosphere than that of the 1982 El Chichon volcanic event. It is important to examine the variations of the extinction coefficient of these two high-altitude cloud systems for the posteruption years of the Pinatubo volcanic event for further evidence of the impact of volcanic aerosols on high-altitude clouds. C1 NASA, LANGLEY RES CTR, DIV ATMOSPHER SCI, HAMPTON, VA 23681 USA. RP WANG, PH (reprint author), SCI & TECHNOL CORP, POB 7390, HAMPTON, VA 23666 USA. RI Minnis, Patrick/G-1902-2010 OI Minnis, Patrick/0000-0002-4733-6148 NR 81 TC 27 Z9 27 U1 1 U2 4 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 2169-897X J9 J GEOPHYS RES-ATMOS JI J. Geophys. Res.-Atmos. PD FEB 20 PY 1995 VL 100 IS D2 BP 3181 EP 3199 DI 10.1029/94JD02325 PG 19 WC Meteorology & Atmospheric Sciences SC Meteorology & Atmospheric Sciences GA QJ630 UT WOS:A1995QJ63000037 ER PT J AU WALCH, SP PARTRIDGE, H AF WALCH, SP PARTRIDGE, H TI ACCURATE ENERGETICS FOR THE UNIMOLECULAR DECOMPOSITION OF HN2 SO CHEMICAL PHYSICS LETTERS LA English DT Article ID CONFIGURATION-INTERACTION CALCULATIONS; GAUSSIAN-BASIS SETS; THEORETICAL CHARACTERIZATION; ENERGY; ATOMS; COMBUSTION; SURFACE; 1ST-ROW AB We report internally contracted configuration interaction calculations of the barrier to unimolecular decay of HN, with cc-pVDZ, cc-pVTZ, cc-pVQZ, and cc-pV5Z basis sets. Extrapolation to the basis set limit gives a barrier height within 0.1 kcal/mol of that used to calibrate the HN2 potential energy surface used by Koizumi, Schatz, and Walch in coupled channel calculations to determine the lifetimes of the lowest vibrational levels of HN2. RP WALCH, SP (reprint author), NASA,AMES RES CTR,INST THERMOSCI,MS 230-3,MOFFETT FIELD,CA 94035, USA. NR 19 TC 17 Z9 18 U1 0 U2 3 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD FEB 17 PY 1995 VL 233 IS 4 BP 331 EP 334 DI 10.1016/0009-2614(94)01471-7 PG 4 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QG952 UT WOS:A1995QG95200001 ER PT J AU BENSON, BD FRANCISCO, JS AF BENSON, BD FRANCISCO, JS TI AN AB-INITIO STUDY OF THE STRUCTURE, VIBRATIONAL FREQUENCIES AND HEAT OF FORMATION OF ONCO RADICAL SO CHEMICAL PHYSICS LETTERS LA English DT Article AB The structure, infrared vibrational frequencies, and heat of formation of ONCO radical were calculated using ab initio molecular orbital theory. Calculations were performed using various basis sets in conjunction with various post-Hartree-Fock methods. The most elaborate optimized geometry was calculated using quadratic configuration interaction theory with perturbative correction for the triples (QCISD(T)) with the 6-311G(2d, 2p) basis set. At this level of theory the structure is bound with an N-C bond length of 1.283 Angstrom. Using G2 theory the heat of formation of ONCO radical is 20.2 kcal mol(-1). C1 CALTECH,JET PROP LAB,PASADENA,CA 91109. NR 6 TC 8 Z9 8 U1 0 U2 1 PU ELSEVIER SCIENCE BV PI AMSTERDAM PA PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS SN 0009-2614 J9 CHEM PHYS LETT JI Chem. Phys. Lett. PD FEB 17 PY 1995 VL 233 IS 4 BP 335 EP 339 DI 10.1016/0009-2614(94)01482-B PG 5 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QG952 UT WOS:A1995QG95200002 ER PT J AU BARTLETT, JG BLANCHARD, A SILK, J TURNER, MS AF BARTLETT, JG BLANCHARD, A SILK, J TURNER, MS TI THE CASE FOR A HUBBLE CONSTANT OF 30 KM S(-1) MPC(-1) SO SCIENCE LA English DT Article ID COLD DARK-MATTER; LARGE-SCALE STRUCTURE; PRIMORDIAL NUCLEOSYNTHESIS; GALAXY CLUSTERS; REDSHIFT SURVEY; IRAS GALAXIES; UNIVERSE; HOT; ANISOTROPY; COSMOLOGY AB Although recent determinations of the distance to the Virgo cluster based on Cepheid variable stars represent an important step in pinning down the Hubble constant, after 65 years a definitive determination of the Hubble constant still eludes cosmologists. At present, most of the observational determinations place the Hubble constant between 40 and 90 kilometers per second per megaparsec (km s(-1) Mpc(-1)). The case is made here for a Hubble constant that is even smaller than the lower bound of the accepted range on the basis of the great advantages, all theoretical in nature, of a Hubble constant of around 30 kilometers per second per megaparsec. Such a value for the Hubble cures all of the ills of the current theoretical orthodoxy, that is, a spatially flat universe composed predominantly of cold dark matter. C1 UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720. UNIV CALIF BERKELEY,DEPT PHYS,BERKELEY,CA 94720. UNIV CALIF BERKELEY,CTR PARTICLE ASTROPHYS,BERKELEY,CA 94720. FERMILAB NATL ACCELERATOR LAB,NASA,FERMILAB ASTROPHYS CTR,BATAVIA,IL 60510. UNIV CHICAGO,ENRICO FERMI INST,DEPT PHYS,CHICAGO,IL 60637. UNIV CHICAGO,ENRICO FERMI INST,DEPT ASTRON & ASTROPHYS,CHICAGO,IL 60637. RP BARTLETT, JG (reprint author), UNIV STRASBOURG 1,OBSERV ASTRON STRASBOURG,11 RUE UNIV,F-67000 STRASBOURG,FRANCE. OI silk, joe/0000-0002-1566-8148 NR 61 TC 48 Z9 48 U1 0 U2 7 PU AMER ASSOC ADVAN SCIENCE PI WASHINGTON PA 1333 H ST NW, WASHINGTON, DC 20005 SN 0036-8075 J9 SCIENCE JI Science PD FEB 17 PY 1995 VL 267 IS 5200 BP 980 EP 983 DI 10.1126/science.267.5200.980 PG 4 WC Multidisciplinary Sciences SC Science & Technology - Other Topics GA QG990 UT WOS:A1995QG99000026 PM 17811436 ER PT J AU XU, Y SHAKOURI, A YARIV, A KRABACH, T DEJEWSKI, S AF XU, Y SHAKOURI, A YARIV, A KRABACH, T DEJEWSKI, S TI DIRECT MEASUREMENT OF DOPING DENSITY AND BARRIER LOWERING EFFECT WITH BIAS IN QUANTUM-WELLS SO ELECTRONICS LETTERS LA English DT Article DE SEMICONDUCTOR DOPING; SEMICONDUCTOR QUANTUM WELLS; INFRARED DETECTORS ID INFRARED PHOTODETECTORS AB An experimental method for determining the doping density in thin-sheet semiconductor material such as quantum wells (QWs) is demonstrated in GaAs/AlGaAs multiquantum-well infra-red photodetectors. The results agree very well with the conventional Hall measurement method. Barrier lowering effect with bias in QWs is determined experimentally. C1 CALTECH,JET PROP LAB,PASADENA,CA 91125. RP XU, Y (reprint author), CALTECH,DEPT APPL PHYS,PASADENA,CA 91125, USA. NR 6 TC 2 Z9 2 U1 0 U2 0 PU IEE-INST ELEC ENG PI HERTS PA MICHAEL FARADAY HOUSE SIX HILLS WAY STEVENAGE, HERTS, ENGLAND SG1 2AY SN 0013-5194 J9 ELECTRON LETT JI Electron. Lett. PD FEB 16 PY 1995 VL 31 IS 4 BP 320 EP 321 DI 10.1049/el:19950180 PG 2 WC Engineering, Electrical & Electronic SC Engineering GA QL564 UT WOS:A1995QL56400055 ER PT J AU LEE, TJ AF LEE, TJ TI A COUPLED-CLUSTER STUDY OF THE MOLECULAR-STRUCTURE, VIBRATIONAL-SPECTRUM, AND HEATS OF FORMATION OF XONO(2) (X=H,F,CL) SO JOURNAL OF PHYSICAL CHEMISTRY LA English DT Article ID POLAR STRATOSPHERIC CLOUDS; SULFURIC-ACID SURFACES; CHLORINE NITRATE; NITRIC-ACID; HETEROGENEOUS REACTIONS; HYDROGEN-CHLORIDE; OZONE DEPLETION; ELECTRON CORRELATION; WATER; CLONO2 AB The equilibrium structures, harmonic vibrational frequencies, dipole moments, and IR intensities of nitric acid, fluorine nitrate, and chlorine nitrate have been investigated by using the singles and doubles coupled-cluster method that also includes a perturbational estimate of the effects of connected triple excitations, CCSD-(T). A standard triple-zeta double-polarized basis set was utilized. The equilibrium geometries and vibrational spectra of HONO2 and ClONO2 are shown to be in excellent agreement with the available experimental data. The ab initio vibrational spectrum of FONO2 is also shown to be in excellent agreement with experiment. Unlike the FOOF and FON molecules, but similar to the cis- and trans-FONO molecules, FONO2 is shown to possess normal bond distances. The bonding in FONO2 is shown to be more similar to that in ClONO2 than that in HONO2, although there are still significant differences, especially in the partial atomic charges as deduced from Mulliken populations. This causes FONO2 to possess almost no dipole moment, which is very different to both HONO2 and ClONO2. By using large atomic natural orbital basis sets, CCSD(T) energies are computed for four isodesmic reactions in order to determine an accurate heat of formation for FONO2. Our best estimate for Delta H degrees(f,298)(FONO2) is 3.1 +/- 2.0 kcal/mol, indicating that the F-ONO2 bond energy is 31.3 kcal/mol. RP LEE, TJ (reprint author), NASA, AMES RES CTR, MOFFETT FIELD, CA 94035 USA. RI Lee, Timothy/K-2838-2012 NR 50 TC 56 Z9 57 U1 0 U2 1 PU AMER CHEMICAL SOC PI WASHINGTON PA 1155 16TH ST, NW, WASHINGTON, DC 20036 USA SN 0022-3654 J9 J PHYS CHEM-US JI J. Phys. Chem. PD FEB 16 PY 1995 VL 99 IS 7 BP 1943 EP 1948 DI 10.1021/j100007a025 PG 6 WC Chemistry, Physical SC Chemistry GA QG924 UT WOS:A1995QG92400025 ER PT J AU WOO, R PATZOLD, M AF WOO, R PATZOLD, M TI VARIATION OF FRACTIONAL ELECTRON-DENSITY FLUCTUATIONS INSIDE 40-R(O) OBSERVED BY ULYSSES RANGING MEASUREMENTS SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID RADIO SCATTERING OBSERVATIONS; SOLAR-WIND TURBULENCE; SCINTILLATION; EVOLUTION; SPECTRUM; WAVES; SUN AB The first measurements of fractional electron density fluctuations deltan(e)/n(e), where deltan(e) is rms electron density fluctuation and n(e) is the mean electron density, have been carried out inside 40 R(o) using 1991 Ulysses dual-frequency S- and X-band (13 and 3.6 cm) ranging (time delay) measurements. In the frequency band of approximately 6 x 10(-5) - 8 x 10(-4) Hz (periods of 20 min to 5 hr), deltan(e)/n(e) varies from a high near 20% in the slow wind close to the neutral line to a low of 1% in the fast wind far from the neutral line. For spatial wavenumber K approximately 1.4 x 10(-6) km-1 (period of 5 hr at 250 km/s), deltan(e)/n(e) is essentially independent of heliocentric distance over 0.03-1.0 AU in the slow wind; it is a factor of 30 lower in the fast wind than in the slow wind inside 0.1 AU, but exhibits dramatic growth with heliocentric distance inside 0.3 AU. This latter result reinforces current views of the evolution of MHD turbulence and the association of Alfven waves with high speed streams based on in situ fields and particles measurements beyond 0.3 AU. That regions of enhanced density fluctuations near or above the neutral line coincide with regions of enhanced density confirms previous conclusions that they are the interplanetary manifestation of the heliospheric current sheet and extensions of coronal streamers. While the regions of enhanced density fluctuations lie within those of enhanced density, they have boundaries that are distinctly more abrupt, suggesting the separation of plasma of different nature and origin. C1 UNIV BONN, INST RADIOASTRON, W-5300 BONN, GERMANY. UNIV COLOGNE, INST GEOPHYS & METEOROL, W-5000 COLOGNE 41, GERMANY. RP WOO, R (reprint author), JET PROP LAB, PASADENA, CA 91109 USA. NR 26 TC 42 Z9 43 U1 0 U2 1 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 1995 VL 22 IS 4 BP 329 EP 332 DI 10.1029/94GL03335 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QJ265 UT WOS:A1995QJ26500002 ER PT J AU CUMMINGS, AC MEWALDT, RA BLAKE, JB CUMMINGS, JR FRANZ, M HOVESTADT, D KLECKER, B MASON, GM MAZUR, JE STONE, EC VONROSENVINGE, TT WEBBER, WR AF CUMMINGS, AC MEWALDT, RA BLAKE, JB CUMMINGS, JR FRANZ, M HOVESTADT, D KLECKER, B MASON, GM MAZUR, JE STONE, EC VONROSENVINGE, TT WEBBER, WR TI ANOMALOUS COSMIC-RAY OXYGEN GRADIENTS THROUGHOUT THE HELIOSPHERE SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID SOLAR; DRIFT; TRANSPORT AB We have used data from the SAMPEX, Ulysses, Voyager 1, Voyager 2, and Pioneer 10 spacecraft to determine the radial and latitudinal gradients of anomalous cosmic ray oxygen at 10 MeV/nuc during the last half of 1993. These five spacecraft cover radial distances from 1 AU (SAMPLEX) to 58 AU (P10) and latitudes to 41-degrees-S (Ulysses) and 32-degrees-N (V1). We find that the radial gradient is a decreasing function of radial distance, approximately r(-n), with n = 1.7 +/- 0.7. The large-scale radial gradient between the inner and outer heliosphere is much smaller than it was during the last solar minimum period in approximately 1987. The latitudinal gradient is small and positive, 1.3 +/- 0.4%/deg, as opposed to the large and negative latitudinal gradients found during 1987, but similar to the small positive latitudinal gradient measured during 1976 for anomalous cosmic ray helium. These observations confirm that effects of curvature and gradient drift in the large scale magnetic field of the Sun are important for establishing the three-dimensional intensity distributions of these particles in the heliosphere during periods of solar minimum conditions. C1 AEROSP CORP,EL SEGUNDO,CA 90245. MPI AERON,KATLENBURG DUHM,GERMANY. MPI EXTRATERR PHYS,GARCHING,GERMANY. UNIV MARYLAND,COLLEGE PK,MD 20742. NASA,GODDARD SPACE FLIGHT CTR,GREENBELT,MD 20771. NEW MEXICO STATE UNIV,LAS CRUCES,NM 88003. RP CUMMINGS, AC (reprint author), CALTECH,PASADENA,CA 91125, USA. NR 16 TC 33 Z9 33 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 FEB 15 PY 1995 VL 22 IS 4 BP 341 EP 344 DI 10.1029/94GL03343 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QJ265 UT WOS:A1995QJ26500005 ER PT J AU REINER, MJ DESCH, MD KAISER, ML MANNING, R FAINBERG, J STONE, RG AF REINER, MJ DESCH, MD KAISER, ML MANNING, R FAINBERG, J STONE, RG TI ELLIPTICALLY POLARIZED BURSTY RADIO EMISSIONS FROM JUPITER SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article AB We report a new component of Jovian radio emission observed by the Ulysses spacecraft when Ulysses was at high Jovigraphic latitudes (greater-than-or-similar-to 30-degrees north or south of the Jovian magnetic equator). This bursty high-latitude emission is elliptically polarized in the right-hand sense when observed from northern latitudes and in the left-hand sense when observed from southern latitudes, consistent with extra-ordinary mode. The orientation of the polarization ellipse is observed to systematically vary with time relative to the observer. It is argued that the elliptically-polarized nature of the emission is intrinsic to the source region. C1 NASA,GODDARD SPACE FLIGHT CTR,EXTRATERR PHYS LAB,GREENBELT,MD 20771. OBSERV PARIS,F-92190 MEUDON,FRANCE. RP REINER, MJ (reprint author), HUGHES STX,LANHAM,MD 20706, USA. NR 8 TC 7 Z9 7 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 FEB 15 PY 1995 VL 22 IS 4 BP 345 EP 348 DI 10.1029/94GL03280 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QJ265 UT WOS:A1995QJ26500006 ER PT J AU TUBIELLO, FN OPPENHEIMER, M AF TUBIELLO, FN OPPENHEIMER, M TI IMPULSE-RESPONSE FUNCTIONS AND ANTHROPOGENIC CO2 SO GEOPHYSICAL RESEARCH LETTERS LA English DT Article ID ATMOSPHERIC CARBON-DIOXIDE; OCEAN AB Non-linearities in the carbon cycle make the response to atmospheric CO2 perturbations dependent on emission history. We show that even when linear representations of the carbon cycle are used, the calculation of time scales characterizing the removal of excess CO2 depends on past emissions. C1 ENVIRONM DEF FUND,NEW YORK,NY. NYU,DEPT EARTH SYST SCI,NEW YORK,NY 10003. RP TUBIELLO, FN (reprint author), COLUMBIA UNIV,GODDARD INST SPACE STUDIES,2880 BROADWAY,NEW YORK,NY 10025, USA. NR 22 TC 8 Z9 8 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0094-8276 J9 GEOPHYS RES LETT JI Geophys. Res. Lett. PD FEB 15 PY 1995 VL 22 IS 4 BP 413 EP 416 DI 10.1029/94GL03276 PG 4 WC Geosciences, Multidisciplinary SC Geology GA QJ265 UT WOS:A1995QJ26500023 ER PT J AU CHO, PS GOLDHAR, J LEE, CH SADDOW, SE NEUDECK, P AF CHO, PS GOLDHAR, J LEE, CH SADDOW, SE NEUDECK, P TI PHOTOCONDUCTIVE AND PHOTOVOLTAIC RESPONSE OF HIGH-DARK-RESISTIVITY 6H-SIC DEVICES SO JOURNAL OF APPLIED PHYSICS LA English DT Article ID SILICON-CARBIDE; DIAMOND C1 WEAPONS TECHNOL DIRECTORATE,ARMY RES LAB,ADELPHI,MD 20783. NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHO, PS (reprint author), UNIV MARYLAND,DEPT ELECT ENGN,COLLEGE PK,MD 20742, USA. NR 30 TC 16 Z9 22 U1 0 U2 7 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 FEB 15 PY 1995 VL 77 IS 4 BP 1591 EP 1599 DI 10.1063/1.358912 PG 9 WC Physics, Applied SC Physics GA QG500 UT WOS:A1995QG50000036 ER PT J AU MA, Q TIPPING, RH HARTMANN, JM BOULET, C AF MA, Q TIPPING, RH HARTMANN, JM BOULET, C TI DETAILED BALANCE IN FAR-WING LINE-SHAPE THEORIES - COMPARISONS BETWEEN DIFFERENT FORMALISMS SO JOURNAL OF CHEMICAL PHYSICS LA English DT Note ID INFRARED-ABSORPTION SPECTRA; WATER CONTINUUM ABSORPTION; STATISTICAL-THEORY; ROTATIONAL BANDS; REGION; VAPOR; CO2 C1 NASA,GODDARD SPACE FLIGHT CTR,INST SPACE STUDIES,NEW YORK,NY 10025. UNIV ALABAMA,DEPT PHYS & ASTRON,TUSCALOOSA,AL 35487. LAB PHYS MOLEC & APPL,CNRS,UPR 136,F-91405 ORSAY,FRANCE. RP MA, Q (reprint author), COLUMBIA UNIV,DEPT APPL PHYS,NEW YORK,NY 10025, USA. NR 26 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 0021-9606 J9 J CHEM PHYS JI J. Chem. Phys. PD FEB 15 PY 1995 VL 102 IS 7 BP 3009 EP 3010 DI 10.1063/1.468610 PG 2 WC Chemistry, Physical; Physics, Atomic, Molecular & Chemical SC Chemistry; Physics GA QF821 UT WOS:A1995QF82100037 ER PT J AU HALPERN, D CHAO, Y MA, CC MECHOSO, CR AF HALPERN, D CHAO, Y MA, CC MECHOSO, CR TI COMPARISON OF TROPICAL PACIFIC TEMPERATURE AND CURRENT SIMULATIONS WITH 2 VERTICAL MIXING SCHEMES EMBEDDED IN AN OCEAN GENERAL-CIRCULATION MODEL AND REFERENCE TO OBSERVATIONS SO JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS LA English DT Article ID WIND STRESS; TURBULENCE; PARAMETERIZATION; PROFILER AB The Pacanowski-Philander (PP) and Mellor-Yamada (MY) parameterization models of vertical mixing by turbulent processes were embedded in the Geophysical Fluid Dynamics Laboratory high-resolution ocean general circulation model of the tropical Pacific Ocean. All other facets of the numerical simulations were the same. Simulations were made for the 1987-1988 period. At the equator the MY simulation produced near-surface temperatures more uniform with depth, a deeper thermocline, a deeper core speed of the Equatorial Undercurrent, and a South Equatorial Current with greater vertical thickness compared with that computed with the PP method. Along 140 degrees W, between 5 degrees N and 10 degrees N, both simulations were the same. Moored-buoy current and temperature observations had been recorded by the Pacific Marine Environmental Laboratory at three sites (165 degrees E, 140 degrees W, 110 degrees W) along the equator and at three sites (5 degrees N, 7 degrees N, 9 degrees N) along 140 degrees W. Simulated temperatures were lower than those observed in the near-surface layer and higher than those observed in the thermocline. Temperature simulations were in better agreement with observations compared to current simulations. At the equator, PP current and temperature simulations were more representative of the observations than MY simulations. C1 UNIV CALIF LOS ANGELES,DEPT ATMOSPHER SCI,LOS ANGELES,CA 90024. RP HALPERN, D (reprint author), CALTECH,JET PROP LAB,DIV EARTH & SPACE SCI,4800 OAK DR,MS 300-323,PASADENA,CA 91109, USA. NR 33 TC 22 Z9 24 U1 0 U2 0 PU AMER GEOPHYSICAL UNION PI WASHINGTON PA 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 SN 0148-0227 J9 J GEOPHYS RES-OCEANS JI J. Geophys. Res.-Oceans PD FEB 15 PY 1995 VL 100 IS C2 BP 2515 EP 2522 DI 10.1029/94JC03043 PG 8 WC Oceanography SC Oceanography GA QK372 UT WOS:A1995QK37200015 ER PT J AU CHOI, SR SANDERS, WA SALEM, JA TIKARE, V AF CHOI, SR SANDERS, WA SALEM, JA TIKARE, V TI YOUNGS MODULUS, STRENGTH AND FRACTURE-TOUGHNESS AS A FUNCTION OF DENSITY OF IN-SITU TOUGHENED SILICON-NITRIDE WITH 4-WT-PERCENT SCANDIA SO JOURNAL OF MATERIALS SCIENCE LETTERS LA English DT Article C1 NASA,LEWIS RES CTR,CLEVELAND,OH 44135. RP CHOI, SR (reprint author), CLEVELAND STATE UNIV,CLEVELAND,OH 44115, USA. NR 9 TC 7 Z9 7 U1 0 U2 1 PU CHAPMAN HALL LTD PI LONDON PA 2-6 BOUNDARY ROW, LONDON, ENGLAND SE1 8HN SN 0261-8028 J9 J MATER SCI LETT JI J. Mater. Sci. Lett. PD FEB 15 PY 1995 VL 14 IS 4 BP 276 EP 278 DI 10.1007/BF00275622 PG 3 WC Materials Science, Multidisciplinary SC Materials Science GA QN517 UT WOS:A1995QN51700017 ER EF